SPECIFICATION METHOD OF MANUFACTURING OPTICAL DISC, STAMPER, SIGNAL PROCESSING METHOD, SIGNAL PROCESSING APPARATUS, IMAGE DRAWING METHOD, OPTICAL DISC RECORDING APPARATUS, AND OPTICAL RECORDING MEDIUM [0001] Field of Invention The present invention relates to an optical disc capable of recording and reproducing information using laser light, and more particularly, to an optical disc on which a drawing of a visible image can be performed using laser light. In addition, the invention relates to a stamper suitable for the optical disc manufacturing and a method of manufacturing an optical disc. Furthermore, the invention relates to a signal processing method that can be used in an optical disc according to the invention, a signal processing apparatus, an image drawing method, an optical disc recording apparatus, and an optical recording medium. [0002] Description of the Related Art In a representative structure of a write-once type compact disc (referred to as a CD-R) on which information can be recorded once using laser light, a recording layer (i.e., an information recording layer) formed by using an organic dye on a transparent disk shape substrate, a light reflective layer formed of metal such as gold, and a protection layer formed by using a resin material are laminated in this order. An information recording on this CD-R is performed by irradiating near infrared laser light (e.g., having a wavelength of 780 nm) onto a CD-R. An irradiated part of the information recording layer absorbs the light and its temperature is locally increased, so that physical or chemical changes (e.g., generation of a pit) are generated to change its optical characteristics. As a result, information is recorded. [0003] Recently, optical recording media having a higher recording density and called a write-once type digital versatile disc (referred to as DVD-R) has been proposed and commercially used. The DVD-R has a structure obtained by bonding two discs, of which a disc is manufactured by forming an information recording layer including dyes on a transparent disk shape substrate having a guide groove (a pre-groove) for tracking the irradiated laser light, in which the range of the track pitch thereof is 0.74 to 0.8 µm, which is narrower than that of the CD-R, typically forming a reflective layer on the information recording layer, and forming a protection layer as necessary. Alternatively, the DVD-R has a structure obtained by bonding a disc having the above-described structure and a disc-shaped protection substrate having the same shape as that of the disc so that the information recording layer is interposed inside (adhered to the protection substrate) using an adhesive. Recording and reproduction of information to/from the DVD-R is performed by irradiating visible laser light (having a wavelength of 630 to 680 nm), so that a higher density recording can be performed in comparison with CD-R. [0004] It is known that a label, on which visible information such as a title of music data recorded on the recording surface or an identification title for identifying the recorded data is printed, may be attached on a surface opposite to the recording surface of the above optical disc on which music data are recorded. Such an optical disc is manufactured by previously printing the titles or the like on a circular label sheet using a printer or the like and attaching the label sheet on a surface opposite to the recorded surface of the optical disc. [0005] When an optical disc having a desired visible image such as the above titles printed on the label surface (i.e., a surface opposite to a surface onto which laser light is irradiated during recording or reproduction) is manufactured, a printer should be prepared in addition to an optical disc drive. Therefore, it is necessary to perform cumbersome works such as drawing out the optical disc from the optical disc drive or attaching the printed label sheet printed by the separately prepared printer after the recording is performed on a recording surface of an optical disc using an optical disc drive. [0006] In view of this, an optical disc recording apparatus capable of drawing an image on the label surface as well as recording and reproducing the information by using laser light has been proposed (as disclosed in Patent Document I). This optical disc recording apparatus is made for an optical disc having a thermosensitive layer on the label surface, and makes a visible image by scarming a laser pickup and imagewisely irradiating laser light onto the thermosensitive layer (or an image recording layer) to change the color of the irradiated portions. [0007] In addition, an optical disc having an ink receiving layer (a printing layer) on a label surface is also commercially available. Users can print a photograph or an image on this printing layer using an ink-jet printer or the like. However, since users should acquire an ink-jet printer for forming an image on such an optical disc, the optical disc of this kind causes a cost burden to users. Processes of recording information on the optical disc and then transferring it to the ink jet printer to form an image are cumbersome to users. In addition, when information is recorded on a plurality of optical discs and images are provided for them, such processes become more complicated. [0009] Accordingly, an image forming apparatus and image forming method, capable of recording a high contrast ratio image on the optical disc in addition to an information recording (a digital data recording) for a recording surface has been proposed (as disclosed in Patent Document 2). However, this image forming apparatus and image forming method lacks accuracy and stability because a drawing thereby is performed without tracking. This shortcoming can be overcome by loading information for the drawing into the optical disc and reading the information using a recorder. [0010] On the other hand, various kinds of optical discs capable of representing visible information using a contrast caused by difference of reflection between a laser-light-irradiated part and a non-laser-light-irradiated-part on a surface opposite to the information recording layer for recording digital information have been proposed (for example, as disclosed in Patent Documents 3 to 5). [0011] In an optical disc having the image recording layer, an inner circle of the image recording layer is not a perfect circle but a slightly distorted circle. Therefore, when a user tries to perform an image drawing to an inner circumferential region of the image recording layer, it would be locally projected toward inside. Therefore, appearance of image recording layer may be deteriorated in its inner circumferential region. In addition, when a prepit or a pregroove for recording disc information is provided between the inner circumference of the image recording layer and a center hole (for example, a portion which resides outside a region of a diameter of 21 mm to inside and a region of a diameter of 24 mm), and an image is drawn to the inner circumference of the image recording layer, the prepit or the pregroove may be badly influenced, and finally, errors may occur during the reading operation. [0012] On the other hand, it is possible to perform a higher quality drawing by forming a prepit on the image recording layer of the optical disc and making the disc drive to recognize whether or not the image recording layer of the optical disc is, or by storing information on optimal drawing conditions for each disc using the prepit and reading the information when the image is drawn to perform the drawing based on these conditions. In addition, although the prepit region is formed in, for example, the inner circumference of the optical disc (within a diameter range between 21 and 24 mm), a problem may occur in the signal reading when the image recording layer is also formed on the prepit region. In other words, there may be following differences if the image recording layer is not provided in an upper layer of the prepit region. When the image recording layer is not provided in an upper layer of the prepit region, a reflectance of a prepit portion is lower than that of a portion which resides between the prepits, so that the signal is generated based on these reflectance differences, equalized, and decoded to obtain prepit information. On the contrary, when the image recording layer is provided in an upper layer of the prepit region, the reflectance of a prepit portion is higher that that of a portion which resides between the prepits, so that the polarity of the generated signal is reversed. As a result, the generated signal cannot be used as prepit information when decoded in this condition. [0013] The optical disc recording apparatus is necessary to recognize the optical disc when the image is drawn on a label surface. However, the optical discs disclosed in Patent Documents 3 to 5 do not provide a means for recognizing the optical disc in the optical disc recording apparatus. Patent Document 1: Japanese Patent Application Laid-open (JP-A) No, 2003-203348 Patent Document 2: Japanese Patent Application Laid-open (JP-A) No. 2004-005848 Patent Document 3: Japanese Patent Application Laid-open (JP-A) No. 2000-113516 Patent Document 4: Japanese Patent Application Laid-open (JP-A) No. 2001-283464 Patent Document 5: Japanese Patent Application Laid-open (JP-A) No. 2000-173096 DISCLOSURE OF INVENTION Problems to be solved [0014] The present invention is achieved in consideration of the conventional problems described above. Means to solve the problems [0015] Namely, a first aspect of the invention provides (1-1) an optical disc comprising: an image recording layer onto which a visual image can be drawn by irradiation of laser light; and a prepit or pregroove that records disc information and is formed at an inner side of an image drawing region of the image recording layer, wherein the image recording layer (X)mprises the image drawing region where the visual image is drawn and an image drawing prohibited region where drawing of an image is prohibited, and the prepit or pregroove comprises positional information for the image drawing prohibited region. [0016] One preferable embodiment (1-2) of the optical disc (1-1), the image drawing prohibited region resides between the image drawing region and either the prepit or pregroove. [0017] The first aspect of the invention further provides (1-3) a method for drawing a visual image onto an image recording layer of an optical disc, comprising: identifying positional information for an image drawing prohibited region in a prepit or pregroove that records disc information and is formed at an inner side of an image drawing region of the image recording layer; and controlling image drawing of the visual image so as not to conduct the image drawing in the thus identified image drawing prohibited region, wherein the image recording layer is configured to have the visual image recorded thereon by irradiation of laser light. [0018] The first aspect of the invention further provides (1-4) a method for drawing a visual image onto an image recording layer of an optical disc, comprising: predetermining an image drawing region onto which a visual image is recorded and an image drawing prohibited region within a region in which the image recording layer is formed; and controlling image drawing of the visual image so as to conduct the image drawing only in the thus predetermined image drawing region, wherein the image recording layer is configured to have the visual image recorded thereon by irradiation of laser light. [0019] The first aspect of the invention further provides (1-5) an apparatus for drawing a visual image onto an image recording layer of an optical disc, comprising: a unit for identifying a prepit or pregroove so as to obtain information regarding a position of an image drawing prohibited region; and a unit for controlling drawing of the visual image so as not to conduct the drawing in the image drawing prohibited region, wherein the image recording layer is configured to have the visual image recorded thereon by irradiation of laser light, the image recording layer comprises an image drawing region where the visual image is drawn and an image drawing prohibited region where drawing of an image is prohibited, and the prepit or pregroove comprises positional information for the image drawing prohibited region. [0020] The first aspect of the invention further provides (1-6) an apparatus for drawing a visual image onto an image recording layer of an optical disc, comprising a controlling unit for predetermining an image drawing region onto which a visual image is recorded and an image drawing prohibited region within a region in which the image recording layer is formed and controlling image drawing of the visual image so as to conduct the image drawing only in the thus predetermined image drawing region. [0021] A second aspect of the invention provides (2-1) a method for processing a signal which is based on returned light obtained by irradiating laser light onto an optical disc having a prepit, comprising: reading a prepit signal by irradiating the laser light onto a region in which the prepit resides; reversing a polarity of the prepit signal; and decoding the reversed prepit signal. [0022] One preferable embodiment (2-2) of the method (2-1) further comprises equalizing the prepit signal before or after reversing the polarity of the prepit signal. [0023] Another preferable embodiment (2-3) of the method (2-1) and the method (2-2), the optical disc has an image recording layer capable of drawing a visual image by irradiation of laser light, and at least a portion of the image recording layer is formed on at least a portion of the region in which the prepit resides. In a case where a prepit which resides in a prepit region on which the image recording layer is formed, a polarity of a signal generated from the prepit is opposite to that of a signal generated from a prepit region on which the image recording layer is not formed. Even in such a case, the signal processing method of the embodiment (2-3) enables correcting polarity of the signal by the process of reversing the polarity of the signal so as to apply it to decoding. [0024] The second aspect of the invention further provides (2-4) an apparatus for processing a signal which is based on returned light obtained by irradiating laser light onto an optical disc having a prepit, comprising: a unit for reading a prepit signal by irradiating the laser light onto a region in which the prepit resides; a unit for reversing a polarity of the prepit signal; and a umt for decoding the reversed prepit signal. The signal processing method of the embodiment (2-4) enables reversing the polarity of the prepit signal so as to apply it to decoding in a case where the prepit signal has a polarity which is opposite to that can be recognized by a decoder. [0025] The second aspect of the invention further provides (2-5) a method for drawing a visual image onto an optical disc comprising a prepit and an image recording layer at least a portion of which is formed on at least a portion of a region in which the prepit resides, comprising: reading a prepit signal by irradiating laser light onto the region in which the prepit resides; reversing a polarity of the prepit signal; decoding the reversed prepit signal so as to obtain prepit information; and drawing the visual image in accordance with the prepit information. While a prepit signal has a polarity which is opposite to that can be recognized by a decoder since the prepit resides in a portion of a region on which the image recording layer is formed in the embodiment (2-5), the method of the embodiment (2-5) enables reversing the polarity of the prepit signal by reversing the polarity of the prepit signal so as to apply it to decoding. [0026] The second aspect of the invention further provides (2-6) an apparatus for drawing a visual image onto an optical disc comprising a prepit and an image recording layer at least a portion of which is formed on at least a portion of a region in which the prepit resides, comprising: a unit for reading a prepit signal by irradiating laser light onto the region in which the prepit resides; a unit for reversing a polarity of the prepit signal; a unit for decoding the reversed prepit signal so as to obtain prepit information; and a unit for drawing the visual image in accordance with the prepit information. While a prepit signal has a polarity which is opposite to that can be recognized by a decoder since the prepit resides in a portion of a region on which the image recording layer is formed in the embodiment (2-6), the apparatus of the embodiment (2-6) enables reversing the polarity of the prepit signal by the unit for reversing the polarity of the prepit signal so as to apply it to decoding. [0027] The second aspect of the invention further provides (2-7) an optical disc comprising a substrate and an image recording layer onto which a visual image can be drawn by irradiation of laser light and which is formed on the substrate, wherein information regarding the optical disc is recorded by prepits formed in a region which is for forming the image recording layer and which is provided on the substrate, and reflectance at a prepit portion is higher than that at a portion between the prepits. [0028] Further, a third aspect of the invention provides (3-1) an optical disc comprising a substrate and an image recording layer onto which a visual image can be drawn by irradiation of laser light and which is formed on the substrate, wherein the substrate comprises prepits provided on a surface of the substrate on which the image recording layer is formed, and an average depth (hp) of the prepits is in a range of 100 to 400 nm. When the range is adjusted to be in the range of 100 to 400 nm, signal amplitudes of detected signals become larger and thus the accuracy of reading of the signals can be increased. More specifically with regard to the average depth hp of the prepit, when the region for forming the prepit resides inner side than an image recording layer formation region, the average depth hp of the prepit is preferably in a range of 100 to 250 nm, and is more preferably in a range of 100 to 170 nm. The prepit can be designed to be wider when the prepit resides inner side as described above since such configuration provides better signal characteristics comparing to a configuration in which a dye-containing recording layer is formed on the region for forming the prepit as described in the foUowings. On the other hand, when at least one portion of the image recording layer is formed on the prepit, the average depth hp of the prepit is preferably in a range of 150 to 400 nm, more preferably in a range of 150 to 350 nm, still more preferably in a range of 200 to 330 nm, far more preferably in a range of 230 to 330 nm, and particularly preferably in a range of 230 to 300 nm. These ranges can be preferable in view of increasing the accuracy of reading of the signals because returned light generated after the irradiation of the laser light to the prepit may have influence of the dye when the image recording layer is formed on the prepit. The third aspect of the invention further provides (3-2) an optical disc comprising a substrate and an image recording layer onto which a visual image can be drawn by irradiation of laser light and which is formed on the substrate, wherein the substrate comprises prepits provided on a surface of the substrate on which the image recording layer is formed, and an average half width (W) of the prepits is in a range of 200 to 500 nm. The third aspect of the invention further provides (3-3) an optical disc comprising a substrate and an image recording layer onto which a visual image can be drawn by irradiation of laser light and which is formed on the substrate, wherein the substrate comprises prepits provided on a surface of the substrate on which the image recording layer is formed, a ratio (h1/h2) of an average thickness (h1) of the image recording layer at a convex portion of the prepits relative to an average thickness (h2) of the image recording layer at a concave portion of the prepits is in a range of 0.1 to 0,9, and a depth (hp+h)-h2) of depression of the image recording layer at the concave portion of the prepits is in a range of 70 to 250 nm. The third aspect of the invention has the feature of providing product information regarding the optical disc or information regarding image drawing to the prepit so as to make an optical disc recording apparatus be capable of recognizing the optical disc. Further, since the optical disc of the invention satisfy the specific condition as described above, returned light obtained by irradiating laser light onto the optical disc can be sufficiently obtained and thus the signal detection can be easily performed. Further, the invention can reveal particularly excellent image drawing property by using the information regarding image drawing. Furthermore, the above-described specific shape of the prepit enables making signal amplitudes of detected signals be larger so as to increase the accuracy of reading of the signals. While each of the embodiments (3-1) to (3-3) has the effect of obtaining the returned light to easily perform the signal detection, the accuracy of the signal detection can be further increased when any of these embodiments are used in combination, namely, it is further preferable that the invention has any one of the configurations of the combination of the embodiments (3-1) and (3-2), the combination of the embodiments (3-1) and (3-3), the combination of the embodiments (3-2) and (3-3), and the combination of the embodiments (3-1), (3-2) and (3-3). [0029] It is preferable that at least one of the following embodiments (1) to {$) is further applied to the optical disc of the third aspect of the invention. [0030] (1) An embodiment in which the prepit is formed at an inner circumference in the inner portion of the disc relative to the region in which the image forming layer is formed, (2) An embodiment in which at least one portion of the image forming layer is formed on the region in which the prepit is formed. (3) An embodiment in which the average half width (W) of the prepits is in a range of 200 to 500 nm. When the average half width (W) is in a range of 200 to 500 nm, returned light generated after the irradiation of the laser light to optical disc can be sufficiently obtained. Further, when the optical disc is this embodiment, a crosstalk between tracks can be made smaller and a sufficient signal amplitude can be obtained. (4) An embodiment in which a ratio (hi/h2) of an average thickness (h1) of the image recording layer at a convex portion of the prepits relative to an average thickness (h2) of the image recording layer at a concave portion of the prepits is in a range of 0.1 to 0.9, and a depth (hp+h1-h2) of depression of the image recording layer at the concave portion of the prepits is in a range of 70 to 250 nm. When the (h1/h2) and the (hp+hrh2) are within the above ranges, returned light generated after the irradiation of the laser light to optical disc can be sufficiently obtained. Further, when the optical disc is this embodiment, the surface of the image recording layer onto which a reflective layer is formed has an appropriate convex portion and an appropriate concave portion to read the laser light so as to obtain an excellent reproduced signal. (5) An embodiment in which a reflective layer is formed along the image recording layer and the depth (hp+h1-h2) of depression of the image recording layer at the concave portion of the prepits is in a range of 100 to 200 nm. When the (hp+hrh2) is within the above range, returned light generated after the irradiation of the laser light to optical disc can be sufficiently obtained. Further, when the optical disc is this embodiment, an excellent reproduced signal can be obtained. (6) An embodiment in which the image recording layer comprises a dye compound. When the optical disc is this embodiment, the optical disc can be formed to a so-called dye-type optical disc. Since the dye-type optical disc provides a distinctive prepit, it is possible to provide sufficient contrast and visibility to images. (7) An embodiment in which the image recording layer is formed by spin coating a liquid comprising the dye compound. The formation of the optical disc by spin coating enables easily forming the image recording layer and making the optical disc being high productivity. (8) An embodiment in which a thickness of the substrate is in a range of 0.5 to 1.1 mm. When the thickness of the substrate is in a range of 0.5 to 1.1 mm, the drawing using a laser mounted to a DVD-R drive, a DVD+R drive, a DVD recorder or the like becomes possible. (9) An embodiment in which the image recording layer is a layer at which visual information is recorded by irradiating the laser light to substantially the same tracks a plurality of times, and the recording of the visual information is conducted by detecting returned light generated after the irradiation of the laser light to the prepits. When the optical disc is this embodiment, a drive or a recorder can recognize the optical disc as one to which c images can be drawn. Further, contrast of drawn images can be improved by the plurality of times of the irradiation. (10) An embodiment in which the image recording layer is a layer at which visual information is recorded by irradiating the laser light to substantially the same tracks a plurality of times with fluctuating the laser light in a radial direction, and the recording of the visual information is conducted by detecting returned light generated after the irradiation of the laser light to the prepits. When the optical disc is this embodiment, the contrast of drawn images can be further improved. The scope of the invention is not limited to a subject having a disc shape, and may further include an optical information recording medium having a card shape. [0031] The optical recording medium of the third embodiment of the invention is preferably employed in either a system in which the laser light is irradiated to substantially the same tracks a plurality of times as described above or a system in which the laser light is irradiated to substantially the same tracks a plurality of times with fluctuating the laser light in a radial direction as described above. The optical recording medium is capable of making an apparatus sufficiently recognize of information recorded therein so that the apparatus smoothly progress recording of visual information. The optical disc having the prepit which has the above-described specific shape can be used in any of optical disc apparatuses for CD applications (laser wavelengh: 700 nm to 800 nm), DVD applications (laser wavelengh: 600 nm to 700 nm), and Brue-ray discs or HD DVD applications (laser wavelenght: 380 nm to 450 nm). The optical disc is capable of making these apparatuses smoothly detect signals from the optical disc. Among these applications, the optical disc having the prepit which has the above-described specific shape can be specifically preferably used in an optical disc apparatus for DVD applications. The optical recording medium is capable of making an apparatus sufficiently recognize of information recorded therein so that the apparatus smoothly progress recording of visual information. The prepit which has the above-described specific shape enables smooth progress of recording of visual information since the prepit enables sufficient detection of signals even when laser wavelength is in a range of 700 nm to 800 nm. [0032] The third aspect of the invention further provides a stamper for forming a substrate of the optical disc of the invention, the stamper ing convex portions and concave portions that form prepits. Utilization of of the stamper enables efficiently manufacture the optical disc of the invention. Among the convex portions and concave portions, the convex portions of the stamper of the invention have an average height of 150 to 400 nm for forming the prepits each having above-described shape. [0033] The third aspect of the invention further provides a method for forming an optical disc comprising: preparing the stamper of the third aspect of the invention; preparing, by using the stamper, a substrate which has prepits on a surface on which an image recording layer is to be provided; and forming the image recording layer on the surface of the substrate having the prepits. The method for forming an optical disc enables efficiently manufacturing the optical disc of the invention. [0034] The third aspect of the invention further provides a method for a method for processing a signal, comprising: reading a prepit signal by irradiating laser light onto a region of the optical disc of the invention in which prepits reside; reversing a polarity of the prepit signal; and decoding the reversed prepit signal. [0035] The third aspect of the invention further provides an apparatus for processing a signal, comprising: a unit for reading a prepit signal by irradiating laser light onto a region in which prepits reside; a unit for reversing a polarity of the prepit signal; and a unit for decoding the reversed prepit signal. [0036] The third aspect of the invention further provides a method for drawing a visual image onto the optical disc of the invention, comprising: reading a prepit signal by irradiating laser light onto a region in which prepits reside in the optical disc; reversing a polarity of the prepit signal; decoding the reversed prepit signal so as to obtain prepit information, and drawing the visual image in accordance with the prepit information. [0037] The third aspect of the invention further provides an optical disc recording apparatus, comprising: a unit for reading a prepit signal by irradiating laser light onto a region in which prepits reside in the optical disc of the invention; a unit for reversing a polarity of the prepit signal; a unit for decoding the reversed prepit signal so as to obtain prepit information, and a unit for drawing the visual image in accordance with the prepit information. [0038] The third aspect of the invention further provides an optical medium comprising a substrate and an image recording layer onto which a visual image can be drawn by irradiation of laser light and which is formed on the substrate, wherein the substrate comprises prepits provided on a surface of the substrate on which the image recording layer is formed, and an average depth of the prepits (hp) is in a range of 100 to 400 nm. The optical medium can reveals the effects similar to those of the optical disc of the invention. [Effects of the Invention] [0039] The first aspect of the invention can provide: an optical disc having an image recording layer which includes, at an inner side of an image drawing region of the image recording layer, an image drawing prohibited region where drawing of an image is prohibited; an image drawing method; and an apparatus for drawing a visual image to the optical disc, [0040] The second aspect of the invention can provide a method for processing a signal which enables obtaining information provided to the prepit by decoding a prepit signal even if a polarity of the prepit signal is opposite to a polarity of a decoding standard thereof, and an apparatus for processing a signal which performs the method for processing a signal. The second aspect of invention can further provide a method for performing a higher quality of drawing of a visual image onto an optical disc having an image recording layer onto which the visual image can be drawn by irradiation of laser light, an apparatus for drawing a visual image by applying the method for performing a higher quality of drawing of a visual image, and the optical disc. [0041] The third aspect of the invention can provide an optical disc which enables easy detection of a signal related to an image drawing. The third aspect of the invention can further provide a stamper for efficiently forming the optical disc, and a method for manufacturing the optical disc. The third aspect of the invention can further provide a method for processing a signal which enables obtaining information provided to a prepit in the optical disc by decoding a prepit signal, and an apparatus for performing the method for processing a signal. The third aspect of the invention can further provide a method for performing a higher quality of drawing of a visual image onto an optical disc having an image recording layer onto which the visual image can be drawn by irradiation of laser light, an apparatus for drawing a visual image by applying the method for performing a higher quality of drawing of a visual image, and the optical disc. BRIEF DESCRIPTION OF THE DRAWINGS Fig. lA is a partial cross-sectional view illustrating a layer structure of an optical disc according to a first aspect of the present invention,. Fig. IB is a partial cross-sectional view illustrating a layer structure of an optical disc according to second and third aspects of the invention. Fig. 2A is a diagram illustrating an optical disc viewed from an image recording layer according to a first aspect of the invention. Fig. 2B is a partial cross-sectional view illustrating an example of a layer structure including a substrate, an image recording layer, and a reflective layer according to second and third aspects of the invention. Fig. 2C is a top plan view illustrating an optical disc according to a third aspect of the invention. Fig. 3 is a block diagram illustrating an exemplary configuration of an optical disc recording apparatus capable of treating an optical disc of the invention. Fig. 4 is a diagram illustrating a configuration of an optical pickup included in the above optical disc recording apparatus. Fig. 5 is a diagram for describing contents of an image data used to form a visible image for an image recording layer of the optical disc using the optical disc recording apparatus. Fig. 6 is a diagram for describing contents of laser light irradiation control for representing an image gradation when a visible image is formed on an image recording layer of an optical disc of the invention by the optical disc recording apparatus. Fig. 7 is a diagram for describing a method of controlling laser light when a visible image is formed on an image recording layer of the optical disc by the optical disc recording apparatus. Fig. 8 is a diagram for describing contents of laser power control by a laser power control circuit included in the optical disc recording apparatus. Fig. 9 is a diagram illustrating returned laser light for laser light irradiated to an image recording layer of the optical disc from an optical pickup of the optical disc recording apparatus. Fig. 10 is a diagram illustrating an FG pulse generated according to a rotation amount of a spindle motor by a frequency generator 21 included in the optical disc recording apparatus and a clock signal generated according to the FG pulse. Fig. 11 is a flowchart for describing operations of the optical disc recording apparatus. Fig. 12 is a flowchart for describing operations of the optical disc recording apparatus. Fig. 13 is a diagram illustrating a disk ID recorded in the image recording layer of the optical disc. Fig. 14 is a diagram illustrating a shape of the returned light for the laser light received by an photo-receiving device of the optical pickup of the optical disc recording apparatus. Fig. 15 A is a diagram for describing a case where a large size of a beam spot diameter of laser light irradiated on the image recording layer of the optical disc by the optical pickup of the optical disc recording apparatus. Fig. 15B is a diagram for describing a case where a small size of a beam spot diameter of laser light irradiated on the image recording layer of the optical disc by the optical pickup of the optical disc recording apparatus. Fig. 16 is a diagram for describing a method of detecting whether or not a laser light irradiation position of the optical disc recording apparatus passes a reference position of the optical disc. Fig. 17 is a diagram for describing a method of detecting whether or not a laser light irradiation position of the optical disc recording apparatus passes a reference position of the optical disc. Fig. 18 is a timing chart for describing operations of the optical disc recording apparatus when a visible image is formed by irradiating laser light onto an image recording layer of the optical disc. Fig. 19 is a diagram illustrating an image recording layer of the optical disc when laser light is irradiated by the optical disc recording apparatus. Fig. 20 is a top plan view illustrating an optical disc having a print region or the like according to the third aspect of the invention. Fig. 21 is a partial cross-sectional view illustrating an optical disc having a print region or the like according to the third aspect of the invention. DETAILED DESCRIPTION OF THE INVENTION [0043] Hereinafter, embodiments of the present invention will be described. Particularly, an optical disc that can be used in a signal processing method, a signal processing apparatus, an image drawing method, and an optical disc recording apparatus according to the invention will be described, [0044] An optical disc according to the invention has an image recording layer capable of drawing a visible image by irradiating laser light. [0045] According to the first aspect of the invention, the optical disc has disc information recorded by a prepit or pregroove formed in an inner side of an image drawing region of the image recording layer. Advantageously, the image recording layer includes an image drawing region where an image is drawn and an image drawing prohibited region where the drawing of an image is inhibited. More specifically, the prepit or pregroove is formed on a surface of a substrate adjacent to the image recording layer, as will be described later. [0046] Fig. 1A is a partial cross-sectional diagram schematically illustrating a layer structure of an exemplary optical disc according to a first aspect of the invention. As shown in Fig. lA, the optical disc 500 according to a first aspect of the invention includes a first lamination body 520 formed by stacking an information recording layer 514 and a first reflective layer 516 in this order on a first substrate 512, a second lamination body 528 formed by stacking an image recording layer 524 where a visible image is recorded by irradiating laser light and a second reflective layer 526 in this order on a second substrate 522, and an adhesive layer 650 through which the first and second lamination bodys 520 and 528 are adhered such that the first and second reflective layers 516 and 526 face to each other. In addition, a prepit (or a pregroove) 600 is formed in an inner circumference from a formation region of the image recording layer 524 of the second substrate 522. [0047] Fig. 2 A is a diagram illustrating the optical disc 500 of Fig. 1A viewed from the second substrate 522. In the invention, the formation region of the image recording layer 524 includes an image drawing region 5 24A where an image is drawn and an image drawing prohibited region 524B where the drawing of an image is prohibited, as shown in Fig. 2 A. The image drawing region 524A and the image drawing prohibited region 524B are virtual regions that cannot be distinguished from other regions in the image recording layer 524. In addition, the information regarding the position of the image drawing prohibited region 524B may be recorded on the prepit 600. The optical disc recording apparatus, which will be described below, may detect the prepit 600 to recognize the information regarding the position of the image drawing prohibited region and performs a control of the image drawing not to draw an image in the image drawing prohibited region, [0048] As described above, although the optical disc according to the invention has the image drawing prohibited region, where an image drawing is prohibited, in the formation region of the image recording layer, this image drawing prohibited region is preferably located between the image drawing region and the prepit (or pregroove) as shown in Fig, 2A, Errors generated when the prepit (or pregroove) is read can be prevented by forming the image drawing prohibited region in that location. In addition, when the prepit (or pregroove) is not provided, appearance cannot be damaged by prohibiting the image drawing in the image recording layer near an inner circumferential edge where its shape is not a perfect circle. [0049] Although the image drawing prohibited region depends of the size of the formation region of the image recording layer, the image drawing prohibited region is preferably formed within a radius range between 23.5 and 25.0 mm in the optical disc, and more preferably, within a radius range between 24.0 and 24.5 mm. For example, if the inner circumferential diameter of the image recording layer is 20.0 mm, a region within a radius range between 20.0 mm to 20.5 mm can be set as the image drawing prohibited region. In addition, when an outer circumference of the prepit formation region has a radius of 24.0 mm, a radius range between 24.0 and 24.5 mm may be set as the image drawing prohibited region. [0050] An optical disc according to the second aspect of the invention is characterized in that a reflectance of the prepit region is higher than that of an inter-prepit region because information on the optical disc is recorded by the prepit in an image recording layer formation region. In addition, the prepit is formed on a surface of an image recording layer side of a substrate most adjacent to the image recording layer. According to the invention, since information on the drawing of the image recording layer such as a drawing laser power or a light-emitting pattern can be recorded on the prepit, a signal detection relating to the image recording layer can be easily performed. In addition, a different drawing condition may be previously recorded for each optical disc as prepit information, and the drawing can be performed with an optical drawing condition based on this prepit information, so that a high drawing characteristic can be implemented. Information obtained from the prepit may include manufacturer's information and the like. In addition, the most adjacent substrate is a substrate having no pit formed to read the optical information or a substrate more adjacently disposed than an information recording layer contributing to a writing and reproduction of the optical information. [0051] Fig. 1B is a partial cross-sectional view illustrating an example of a layer structure of an optical disc 500 according to second and third aspects of the invention. The optical disc 500 includes a first lamination body 520 formed by depositing an information recording layer 514 and a first reflective layer 516 in this order on a first substrate 512, the second lamination body 528 formed by depositing an image recording layer 524 where a visible image is recorded by irradiating laser light and a second reflective layer 526 in this order on a second substrate 522, an adhesive layer 530 through which the first and second lamination bodies 520 and 528 are bonded such that the first and second reflective layers 516 and 526 face to each other. In addition^ a prepit is provided in a surface on which the image recording layer is formed in the second substrate 522, [0052] In the optical disc according to the second aspect of the invention, the image recording layer 524 is formed to a region where the prepit 600 is provided, as shown in Fig, IB. In other words, the image recording layer 524 is formed in a region of the prepit 600. [0053] According to the third aspect of the invention, a region for forming the prepit is not particularly limited. In other words, the prepit may be formed in an inner circumferential side from a region where the image recording layer is formed. In other words, as shown in Fig. 2C, a region where the prepit 600 is formed (i.e., a prepit formation region) may be disposed in an inner circumferential side from a region where the image recording layer is formed (i.e., an image recording layer formation region 602). As a result, since the prepit is not buried by a dye compound, a signal can be easily detected. [0054] In addition, according to the third aspect of the invention, a margin should be prepared between an outermost circumference of a pit formation region and an innermost circumference of the image recording layer formation region in order not to form the image recording layer on the prepit formation region. From the viewpoint of a larger image recording layer formation region, a region where the prepit 600 is formed may be partially superposed with the image recording layer 524 formed thereon as shown in Fig. IB. In other words, at least a part of the image recording layer 524 may be formed on the prepit 600. When at least a part of the image recording layer 524 may be formed on the prepit 600, yield of the process of manufacturing the optical disc can be increased since the position for forming the image recording layer 24 can be relatively flexibly determined, [0055] Particularly, according to a third aspect of the invention, when the prepit is formed on an inner circumference of the substrate, the prepit may be formed within a radius range between 21 and 24 mm from the center of the substrate. [0056] As shown in Fig. 2B, an average depth hp of the prepit 600 is preferably in a range of 100 to 400 nm. When the range is adjusted to be in the range of 100 to 400 nm, signal amplitudes of detected signals become larger and thus the accuracy of reading of the signals can be increased. More specifically with regard to the average depth hp of the prepit, when the region for forming the prepit resides inner side than an image recording layer formation region 602, the average depth hp of the prepit is preferably in a range of 100 to 250 nm, and is more preferably in a range of 100 to 170 nm. The prepit can be designed to be wider when the prepit resides inner side as described above since such configuration provides better signal characteristics comparing to a configuration in which a dye-containing recording layer is formed on the region for forming the prepit as described in the followings. On the other hand, when at least one portion of the image recording layer 524 is formed on the prepit 600, the average depth hp of the prepit is preferably in a range of 150 to 400 nm, more preferably in a range of 150 to 350 nm, still more preferably in a range of 200 to 330 nm, far more preferably in a range of 230 to 330 nm, and particularly preferably in a range of 230 to 300 nm. These ranges can be preferable in view of increasing the accuracy of reading of the signals because returned light generated after the irradiation of the laser light to the prepit may have influence of the dye when the image recording layer 524 is formed on the prepit 600. [0057] An average half width W measured in a radial direction of the prepit is preferably in a range of 200 to 500 nm, is more preferably in a range of 250 to 450 nm, and is further preferably in a range of 390 to 440 nm. As a result of the average half width W being in the range of 200 to 500 nm, a crosstalk between tracks can be made smaller and a sufficient signal amplitude can be obtained. A length (i,e,, a half width) measured in a circumferential direction of the prepit 600 may be appropriately set as it depends on information to be recorded. In addition, a ratio (h1/h2) of an average thickness (hi) of the image recording layer 524 on a prominence 600 A of the prepit 600 relative to an average thickness (h1) of the image recording layer 524 on a depression 600B of the prepit 600 is preferably in a range of 0.1 to 0.9. The depth (hp+h1-h2) of depression of the image recording layer 524 on the depression of the prepit 600 is preferably in a range of 70 to 250 nm. As a result of maintaining "h1/h2" and "h1/hp+h2" within the above ranges, a surface where the image recording layer 524 and the reflective layer 526 are to be formed can have an appropriate prominence and depression and obtain an excellent reproduction signal. More preferably, the range of "h1/h2" may be between 0.2 and 0,8, and the range of "hp+h1-h2" is preferably in the range of 100 and 200 nm, is more preferably in the range of 120 and 180 nm, and further more preferably in the range of 130 and 170 nm. When the "h1/h2" and "h1/hp+h1" are within the above ranges, the average thickness (hp) of the prepit and the average half width W measured in a radial direction of the prepit are preferably in the above-described ranges respectively. [0059] In addition, as shown in Fig. 2B, the reflective layer 526 is preferably formed along the image recording layer 524. A ratio "t1/t2" between an average thickness t1 of the reflective layer 526 on the prominence 600A of the prepit 600 and an average thickness t2 of the reflective layer on the depression 600B of the prepit 600 is preferably in a range of 0.8 to 1.2, and more preferably in a range of 0,9 to 1.1, [0060] In addition, the above thicknesses hp, h1 and h2 can be obtained using an AFM, a transmissive spectrometer, or an ellipsometer. Alternatively, they may be measured by observing a cross-section of the manufactured optical disc using an SEM, The measurement of the shape of the prepit may be conducted by using an AFM apparatus SPI3800N/SPA500 (trade name, manufactured by Seiko Instruments Inc.) and a plobe NCH-10V (rade name, manufactured by Veeco Instruments), [0061] The substrate having the prepit may be manufactured using a stamper according to the invention. A prominence and depression suitable for forming the prepit is previously provided on the stamper according to the invention. An average height of the prominence of the prominence and depression is preferably in a range of 150 to 400 nm. It is possible to improve efficiency of the optical disc according to the invention by using the above stamper. A process for fabricating the stamper may be similar to a process for fabricating a typical CD-ROM stamper. Specifically, a photoresist is formed on a glass disk and then developed. Subsequently, metal such as nickel can be sputtered and eletrocasted to fabricate the stamper. [0063] The optical disc is preferably used in a system in which laser light is irradiated to substantially the same tracks in a plurality of times as described above or a system in which laser light is fluctuated in a radial direction of the optical disc and irradiated on substantially the same tracks in a plurality of times. Even when the optical recording medium is used in such a system, the apparatus of the invention can sufficiently recognize information on the optical disc. Therefore, it is possible to smoothly process a recording of visible information. [0064] In addition, the optical disc having the specific prepit may be used in any kind of optical disc apparatus used in various laser wavelengths, such as a wavelength range of 700 to 800 nm for a CD application, a wavelength range of 600 to 700 nm for a DVD application, and a wavelength range of 380 to 450 nm for a Brue-Lay disc application and a HD DVD application. In theses apparatuses, it is possible appropriately detect signals from the optical disc due to the specific prepit. Among theses usages, the optical disc having the specific prepit according to the present invention is preferably used in an optical disc apparatus for a DVD application. Since the optical disc apparatus for a DVD application is operated with a laser having a wavelength of 600 to 700 nm, it may not be specifically suitable for detecting signals from the prepit. However, since signals can be sufficiently detected by adopting the specific prepit even if a laser wavelength range of 600 to 700 nm is utilized, recording of visible information can be appropriately conducted. [0065] A configuration of an optical disc according to the invention is not particularly limited as long as the prepit is provided and the image recording layer is formed. In other words, a configuration of an optical disc according to the invention may be adopted in any one of a read-only type, a write-once type, and a rewritable type. Among them a write-once type optical disc is preferable. Also, the recording type is not particularly limited, and can be a phase change type, a magneto optical type, a dye type or the like. Among them, a dye type is preferable. In addition, a layer structure of the optical disc may be configured as follows. (1) A first layer structure is obtained by sequentially forming an information recording layer, a reflective layer, and an adhesive layer on a first substrate, and bonding a second substrate having an image recording layer onto the boding layer. (2) A second layer structure is obtained by sequentially forming an information recording layer, a reflective layer, a protection layer, and an adhesive layer on a first substrate, and boding a second substrate having an image recording layer onto the adhesive layer. (3) A third layer structure is obtained by sequentially forming an information recording layer, a reflective layer, a protection layer, and an adhesive layer on a first substrate, and bonding a second substrate having an image recording layer onto the protection layer. (4) A fourth layer structure is obtained by sequentially forming an information recording layer, a reflective layer, a protection layer, an adhesive layer, a protection layer, and a reflective layer on a first substrate, and bonding a second substrate having an image recording layer onto the reflective layer. (5) A fifth layer structure is obtained by sequentially forming an information recording layer, a reflective layer, an adhesive layer, and a reflective layer on a first substrate, and bonding a second substrate having an image recording layer on the reflective layer. (6) A sixth layer structure is obtained by sequentially forming an information recording layer, a reflective layer, and a protection layer on a first substrate, sequentially forming an information recording layer, a reflective layer, and a protection layer on a second substrate, and adhering the protection layers of both laminations by interposing an adhesive layer therebetween. [0067] The above layer structures (1) to (6) are shown for the purpose of exemplification, and the layer structures of the optical disc may be modified by exchanging some part of them as well as changing their sequence. In addition, a part of them (excluding the information recording layer and the image recording layer) may be omitted. Furthermore, each layer may be configured of a single layer or a plurality of layers. Hereinafter, the substrate and each layer will be described. In addition, in the following description, the first and second substrates may be simply generally called "a substrate". [0068] The layer configuration is preferably applied to a configuration of a DVD (including a DVD-R, a DVD-RW, and HD-DVD), namely, a bonding-type optical disc formed by bonding a first substrate and a second substrate, in which first substrate has provided with the information recording layer, the second substrate has provided with the image recording layer formed on a surface having the prepit. [0069] Hereinafter, the layer structure shown in Fig, 1 will be described in detail for each layer, [0070] Information Recording Layer The information recording layer is a layer on which information is recorded and reproduced by using recording laser light and reproducing laser light. Particularly, code information such as digital information is recorded. While either of a dye recording type recording layer or a phase change type recording layer may be used as the information recording layer, the dye recording type recording layer is more preferably used in the invention. [0071] Examples of a dye included in the dye recording layer may include a cyanine dye, an oxonol dye, an azo dye, a phthalocyanine dye, a triazole compound (including a benzotriazole compound), a triazine compound, a merocianin compound, an aminobutadiene compound, a cinnamic acid compound, a benzo-oxazole compound, a pyrromethene compound, a squarylium compound, and the like. In addition, they may have a metal atom in its coordination center. In addition, dyes disclosed in JP-ANos. 4-74690, 8-127174, 11-53758, 11-334204, 11-334205, 11-334206, 11-334207, 2000-43423, 2000-108513, and 2000-158818 may be used. [0072] If the optical information recording medium is a CD-R, a cyanine dye, an azo dye, and a phthalocyanine dye are preferable as the dye included in the dye recording layer. If the optical information recording medium is a DVD-R, a cyanine dye, an oxonol dye, an azo dye (e.g., a complex of Ni or Co), a pyrromethene compound may be preferable as the dye included in the dye recording layer. If the optical information recording medium is a blue ray disc or a HD-DVD, a cyanine dye, an oxonol dye, an azo dye, a phthalocyanine dye, a benzotriazole compound, and a triazine compound are preferable as the dye included in the dye recording layer. In addition, if the optical information recording medium is a CD-R, a cyanine dye, an azo dye, and a phthalocyanine dye are more preferable as the dye included in the dye recording layer. If the optical information recording medium is a DVD-R, a cyanine dye, an oxonol dye, and an azo dye (e.g., a complex of Ni or Co) are more preferable as the dye included in the dye recording layer. If the optical information recording medium is a blue ray disc or an HD-DVD, a cyanine dye, an oxonol dye, an azo dye, and a phthalocyanine dye are more preferable as the dye included in the dye recording layer. [0073] The information recording layer may be fabricated as follows. A recording material such as a dye is dissolved with an appropriate solvent together with a binder to provide a coating liquid. Then, the coating liquid is coated on the substrate to form a coated film, and then dried. A concentration of the recording material is typically in a range of 0,01 to 15 w/w%, preferably in a range of 0.1 to 10 w/w%, more preferably in a range of 0.5 to 5 w/w%, and most preferably in a range of 0,5 to 3 w/w%. [0074] Examples of a method for forming the information recording layer include a deposition, a sputtering, a CVD, or a solvent spraying, and preferable examples thereof include a solvent spraying. [0075] Examples of a solvent of the coating liquid may include; ester such as butyl acetate, ethyl lactate, and cellosolve acetate; ketone based materials such as methyl ethyl ketone, cyclohexanone, or methyl isobutyl ketone; chlorinated hydrocarbon such as dichloromethane, or 1,2'dichlororethane, chloroform; amide such as dimethylformamide; hydrocarbon such as methylcyclohexane; ethyl such as dibutylether, diethylether, tetrahydropuran, or dioxane; alcohol such as ethanol, n-propanol, isopropanol, n-buthanol, or diacetonealcohol; a fluoric solvent such as 2,2,3,3-tetrafluropropanol; and glycolether such as ethyleneglycolmonomethylether, ethyleneglycolmonoethylether, or propyleneglycolmonomethylether. [0076] A single solvent can be used, or two or more kinds of the above solvents may be combined in consideration with solubility of a dye used in the solvent. In addition, various additives such as an anti-oxidant, a UV absorbing agent, a platicizer, or a lubricant may be added into the coating liquid, [0077] Examples of the binder which mav be used include natural organic polymers such as gelatin, cellulose derivatives, dextran, rosin, or rubber as well as synthetic inorganic polymers including: a hydrocarbonated resin such as polyethylene, polypropylene, polystyrene, or polyisobuthylene; a vinylic resin such as polyvinyl chloride, polyvinylidene chloride, or a copolymer of and a polyvinyl chloride and polyvinyl acetate; an acrylic resin such as polymethylacrylate or polymethylmetacrylate; and an initial condensate of a thermosetting resin such as polyvinylalcohol chlorinated polyethylene, an epoxy resin, a butyral resin, rubber derivatives, or a phenol-formaldehide resin, [0078] When a binder is mixed in a material for the information recording layer, the mixed amount of the binder may be 0.01 to 50 times of an amount of the dye in mass, and is preferably 0.1 to 5 times of an amount of the dye in mass. [0079] Examples of a method for applying the coating liquid may include a spray method, a spin coat method, a dipping method, a roll coat method, a blade coat method, a doctor roll method, a screen printing method, and the like. The information recording layer may be either of a single layer or a double layer. The thickness of the information recording layer is typically in a range of 10 to 500 nm, preferably in a range of 15 to 300 nm, and more preferably in a range of 20 to 150 nm. [0080] The information recording layer may include various kinds of discoloring inhibitors in order to improve lightfastness of the information recording layer, A singlet oxygen quencher is typically used as the discoloring inhibitor. Publications such as patent documents known in the art may be used as the singlet oxygen quencher. Examples of publications disclosing the singlet oxygen quenchers may include: patent documents JP-ANos. 58-175693, 59-31194, 60-18387, 60-19586, 60-19587, 60-35054, 60-36190, 60-36191, 60-44554, 60-44555, 60-44389, 60-44390, 60-54892, 60-47069, 68-209995, and 4-25492, Japanese Patent Application Publication (JP-B) Nos. 1-38680 and 6-26028, and German Patent No. 350399, and a publication of Japanese Chemical Forum, page 1141, October 1992. [0081] The used amount of the discoloring inhibitor such as a singlet oxygen quencher may be in a range of 0.1 to 50 wt/wt%, preferably in a range of 0.5 to 45 wt/wt%, more preferably in a range of 3 to 40 wt/wt%, and most preferably in a range of 5 to 25 wt/wt% relative to an amount of the dye. Examples of materials used in the phase change type information recording layer may include an Sb-Te alloy, a Ge-Sb-Te alloy, a Pd-Ge-Sb-Te alloy, an Nb-Ge-Sb-Te alloy, a Pd-Nb-Ge-Sb-Te alloy, a Pt-Ge-Sb-Te alloy, a Co-Ge-Sb-Te alloy, an In-Sb-Te alloy, an Ag-In-Sb-Te alloy, an Ag-V-In-Sb-Te alloy, and an Ag-Ge-In-Sb-Te alloy. The Ge-Sb-Te alloy and the Ag-In-Sb-Te alloy are preferably used because they are rewritable in multiple times. The thickness of the phase change type information recording layer may be preferably in a range of 10 to 50 nm, and more preferably in a range of 15 to 30 nm, [0083] Examples of a method for forming the phase change type information recording layer include a sputtering method and a vapor film deposition method such as a vacuum deposition method. [0084] First and Second Substrates The first and second substrates of an optical disc according to the invention may be fabricated by using various material used in a conventional optical disc substrate, [0085] Examples of materials used in the substrate may include: glass, polycarbonate, an acrylic resin such as polymethylmetacrylate, a vinyl chloride resin such as polyvinyl chloride or vinyl chloride, an epoxy resin, amorphous polyolephin, polyester, and a combination of any of them as desired. These materials may be formed in the shape of a film or a rigid board. Polycarbonate is preferably used in the invention due to its resistance to humidity, dimensional stability, and cost. [0086] The second substrate may be fabricated by forming the prepit on a side thereof where the image recording layer is formed using a stamper according to the invention. The height of the prominence corresponding to the depth of the prepit may be controlled by adjusting the film thickness of the photoresist. [0087] The thickness of the first and second substrates is preferably in a range of 0.1 to 1.2 mm, preferably in a range of 0.2 to 1.1 mm, more preferably in a range of 0.5 to 1.1 mm, and most preferably in a range of 0.5 to 1.1 mm. If the thickness of the first and second substrate is in a range of 0.5 to 1.1 mm, it is possible to perform image drawing by using a laser mounted in a DVD-R drive, a DVD+R drive, a DVD recorderor the like. Preferably, the first substrate basically includes a groove or a tracking servo signal. The second substrate may also include groove or a tracking servo signal, A track pitch of the groove of the first substrate is preferably in a range of 280 to 450 nm, and more preferably in a range of 300 to 420 nm. In addition, the depth of the groove is preferably in a range of 15 to 150 nm, and more preferably in a range of 25 to 100 nm. [0088] The groove for a tracking may be further formed on the second substrate in order to record a high definition image on the image recording layer. In this case, the track pitch of the groove is preferably in a range of 0.3 to 200 µm, more preferably in a range of 0.6 to 100 µm, and further preferably in a range of 0.7 to 50µm from the viewpoint of the intensity distribution of the recording laser. [0089] In addition, if the thickness of the substrate where a tracking is performed during an image is recorded and laser light is incident is 0.6 mm, the depth of the groove is preferably in a range of 50 to 250 nm, more preferably in a range of 80 to 200 nm, and further preferably in a range of 100 to 180 nm. The width of the groove is preferably in a range of 100 to 600 nm, more preferably in a range of 200 to 500 nm, and most preferably in a range of 250 to 450 nm. Furthermore, an optimal shape of the groove may be different depending on a wavelength of the laser light, a numerical aperture, the thickness of the substrate, or the like. [0090] The surface of the first substrate (where the groove is formed) may include a primer layer in order to improve flatness and adhesion, and prevent deterioration of the information recording layer. Examples of materials for the primer layer may include: polymers such as polymethylmetacrylate, a copolymer of acrylate and metacrylate, a copolymer of styrene and maleic anhydride, polyvinylalcohol, n-methylolacrylamide, a copolymer of styrene and vinyltoluene, chlorosulfonated polyethylene, netrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, a copolymer vinyl acetate and vinyl chloride, a copolymer of ethylene and vinyl acetate, polyethylene, polypropylene, or polycarbonate; and a surface modifier such as a silan coupling agent. The primer layer may be formed by dissolving or dispersing the above material into an appropriate solvent to obtain a coating liquid, applying the coating liquid onto the surface of the substrate using coating methods such as a spin coating, a dip coating, or an extrusion coating. The thickness of the primer layer is typically in a range of 0.005 to 20 )im, preferably in a range of 0.01 to 10µm. On the other hand, in order to prevent reflected images cause by specular reflection light in the visible image drawn on the image recording layer, a surface roughening processing is preferably performed for the second substrate. [00929] There may be various methods for the surface roughening process on the second substrate, and the invention is not particularly limited thereto. However, any of the following first to fifth surface roughening processes is preferably adopted. [0093] (1) In a first surface roughening process, a surface where the image recording layer on the second substrate is to be formed is roughened using a stamper having a roughened surface which will make contact with a surface of the second substrate. Specifically, a roughening process is firstly performed for the stamper which will be used to form the second substrate. The above surface roughening process is performed using a blast method such as a sand blast until a desired roughness is obtained. In addition, a chemical process may be performed as will be described in the fifth surface roughening process. Subsequently, the stamper is installed in a die such that the roughened surface makes contact with a resin material of the second substrate, and a molding is performed through a method known in the art. As a result, the second surface has a roughened surface on only one side. Preferably, the desired roughness may be obtained by setting a maximum height Rz of the roughened surface to 0.3 to 5µm and an average length RSm of a roughening curve element to 10 to 500µm. [0094] (2) In a second surface roughening process, a surface where the image recording layer on the second substrate is to be formed is roughened by using a molding die having a roughened surface which will make contact with the second substrate during the molding process. Specifically, a surface roughening is performed for a main surface of the molding die used to form the second substrate. Similarly to the first surface roughening process, a surface, a molding is performed for the second substrate using the above die through a method known in the art. As a result the second surface has a roughened surface on only one side. [0095] (3) In a third surface roughening process, a resin having fine particles diffused thereto is coated on a surface where the image recording layer is to be formed after the second substrate is fabricated, and then, the resin is cured. As a result, a surface where the image recording layer on the second substrate is to be formed is roughened. Examples of the above resin may include an acrylate based UV cured resin, or an epoxy based or isocyanate based resin. [0096] In addition, the fine particles may be inorganic particles such as those of SiO2 or Al2O3 or resin particles such as those of polycarbonate or acrylic. An average volume diameter of the fine particles may preferably be in a range of 0.3 to 200µm, and more preferably in a range of 0.6 to 100 µm. It is possible to obtain a desired surface roughness by adjusting a diameter and a dosage of the fine particles. [0097] (4) In a fourth surface roughening process, a mechanical machining is performed on a surface where the image recording layer is formed after the second substrate is fabricated, so that a surface where the image recording layer on the second substrate is to be formed is roughened. Although various processes can be performed for the mechanical machining, a blast process such as a sand blast is preferably applied. [0098] (5) In the fifth surface roughening process, a chemical process is performed for a surface where the image recording layer is to be formed after the second substrate is fabricated, so that the a surface where the image recording layer on the second substrate is to be formed is roughened. The chemical process may be performed by coating or spraying a solvent on one surface of the second substrate after the molding and then performing an etching process. Examples of the solvent may preferably include an organic solvent such as dimethylformamide, or an acid solvent such as acetic acid, hydrochloric acid, and sulfuric acid. A desired roughness can be obtained by adjusting a specific concentration of the acid solvent or a coating time. [0099] First and Second Reflective Layers The first and second reflective layers are provided in the vicinity of the image recording layer in order to improve reflectance during information is reproduced. A light reflective material used in the reflective layer has high reflectance for laser light, and examples of the light reflective material may include metal such as Mg, Se, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Co, Ni, Ru, Rh, Pd, Ir, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Si, Ge, Te, Pb, Po, Sn, or Bi, and semimetal or a stainless steel.. A single material may be used, or a combination or an alloy of them including two or more materials may be used. Examples of material for the first and second reflective layers may preferably include Cr, Ni, Pt, Cu, Ag, Au, AI, and a stainless steel, more preferably, Au metal, Ag metal, Al metal, and an alloy of them, and most preferably, Ag metal, Al metal, and an alloy of them. The reflective layer can be formed on the substrate or the information recording layer by depositing, sputtering, or ion-plating the light reflective material. The thickness of the reflective layers is preferably in a range of 10 to 300 nm, and more preferably in a range of 50 to 200 nm. [0100] Adhesive layer The adhesive layer is provided to bond the first lamination body 520 and the second lamination body 528 in Figs. 1A and IB, and disposed between the first and second reflective layers 516 and 526. An adhesive used in the adhesive layer may include a UV curable resin as known in the art. [0101] Image Recording Layer The optical disc according to the invention has an image recording layer opposite to the information recording layer as described above. Visible images (i.e., visible information) such as characters, figures, or patterns desired by users are recorded on the image recording layer. Examples of the visible images may include a disc title, information on contents, a thumbnail of contents, relating logos, designed clip arts, copyright information, a recording data and time, a recording method, a recording format, barcodes, and the like. [0102] The visible image recorded on the image recording layer means an image that can be visually recognized, and examples of the visible image may include all visually recognizable images such as a character (string), a figure, a pattern, or the like. The characters may include various kinds of information such as an allowed persons list, expiration date information, a specified number of use, rental information, resolution selection information, layer selection information, user selection information, a copyright person, a copyright number, a manufacturer, a manufacturing date, a selling date, a bender, a bender shop, a use setup number, local setting information, language selection information, usage selection information, product user information, a password, or the like. [0103] The image recording layer is manufactured to allow image information such as characters, images, or patterns to be visibly recorded by irradiating laser light. The image recording layer preferably includes a dye compound in consideration with a clear pit. The dyes used in the information recording layer may be appropriately adopted as a material for the image recording layer. In this case, the image recording layer is preferably formed through a spin coat method using a coating liquid containing the dye compound. [0104] In addition, in the optical disc according to the invention, while the aforementioned materials (such as dyes or phase change recording materials) of the information recording layer and the materials of the image recording layer may be similarly selected, it is preferable that the components are differently set because required characteristics are different between the image recording layer and the information recording layer. Specifically, it is preferable that the material for the information recording layer may be selected from those having an excellent recording/reproduction characteristic, and the material for the image recording layer may be selected from those that can increase a contrast of the recorded image. Particularly, a cyanine dye, a phthalocyanine dye, an azo dye, an azo metal complex, an oxonol dye are preferably used. [0105] In addition, a leuco dye may be used. Specifically, crystal violet lactone, phtalide compounds such as 3,3-bis(l-ethyl2-ethylindol-3-yl)phtalide or 3-(4-diethyamino-2-etoxyphenyl)-3"(l -ethyl2-methylindol-3-yl)-4-azaphtalide; and fluoran compounds such as 3-cyclohexylmethylamino-6'methyl-7-anylinofluoran, 2"(2-chloroanylino)-6-dibuthylaminofluoran, 3-diethylamino-6-methyl-7-anylinofluoran, 3"dimythylamino-6-methyl-7-xylidinofluoran, 2-(2"Chloroanylino)-6-diethylaminofluoran, 2"anylino-3-methyl-6(N-ethylisopentylamino)fluoran, 3"diethylamino-6-chloro-7-anylinofluoran, 3-benzylethylamino-6-methyl-7-anylinofluoran, or 3-methylpropylamino-6-methyl-7-anylinofluoran may be preferable. [0106] The image recording layer may be formed by dissolving the above dye into a solvent to prepare a coating liquid and applying the coating liquid. The solvent similar to that of the information recording layer may be used. In addition, additives and a coating method are similar to those of the recording layer, [0107] The thickness of the image recording layer is preferably in a range of 0.01 to 200µm, more preferably in a range of 0.05 to 100 µm, and most preferably in a range of 0.1 to 50µm. [0108] In a preferable embodiment, the image recording layer is a layer on which visible information is recorded by irradiating laser light onto approximately the same track in a plurality of times, and the recording of the visible information may be performed by irradiating laser light onto the prepit and detecting its returned light. In another preferable embodiment, the image recording layer is a layer on which the visible information is recorded by irradiating laser light fluctuating in a radial direction of the optical disc onto approximately the same track in a plurality of times, and the recording of the visible information is preferably performed by irradiating the laser light onto the prepit and detecting the returned light. When the image recording layer of the optical disc of invention has a configuration of any of such embodiments, it is possible to have a drive or a recorder recognize that an image can be drawn onto the optical disc. The plurality of times of irradiation of the laser light enables improving contrast of a drawn image. [0109] Hereinafter, a protection layer will be described. Protection Layer A protection layer may be formed in the optical disc of the invention in order to physically and chemically protect the first reflective layer, the information recording layer, the second reflective layer, or the image recording layer. [0110] Examples of a material for forming the protection layer include inorganic materials such as ZnS, ZnS-SiO25 SiO, SiOa, MgF25 SnO2, or Si3N4, or organic materials such as a thermoplastic resin, a thermosetting resin, or a UV curable resin. [0111] In the case that the thermoplastic resin or the thermosetting resin is used as the material for forming the protection layer, the protection layer can be formed by dissolving the materials in an appropriate solvent to obtain a coating liquid, applying the coating liquid, and drying it. In the case that the UV curable resin is used as the material for forming the protection layer, the protection layer can be formed by applying the coating liquid, and curing it by irradiation of UV light. Various additives such as an antistatic agent, an antioxidant, or a UV absorbing agent may be added in the coating liquid according to the purpose. The thickness of the protection layer is typically in a range of 0.1 µm to 1 mm, [0112] In addition, as described above, the optical disc according to the invention may be applied to a so called "read-only optical disc" having, on the first substrate, a recording portion (i.e,, a prepit) where reproducible information is recorded by irradiating laser light. Particularly, variations of the optical disc according to the third aspect of the invention include one that shown in Figs. 20 and 21. Fig. 20 is a top plan view illustrating a configuration in which a print region 702 is formed on a label surface, and an information region 704 and an information recording region (i.e., an image recording layer) 706 are formed from the inner circumference in the inner portion of the disc (i.e., in the side of a forming surface of the label surface of the substrate 720). In addition, as shown in Fig. 21, its partial cross-section includes an image recording region 706 and an information region 704 from the outer circumference between the substrate 710 and the substrate 720. In addition, a print region 702 is formed on a surface of the substrate 720. For example, a product name or a manufacturer's name is printed on the print region, A screen printing may be used as the printing method. As shown in Fig. 20, the innermost end of the optical disc is shielded by forming the print region 702 in the innermost end so that a visual effect of a user can be improved. [0114] The information region 704 is a region on which the prepit according to the invention is formed. On the image recording region 706, a visible image is drawn by the laser light as described above. [0115] In this case, in Fig. 21, rO, that is the innermost end of the print region 702, is preferably is in a range of 8 to 21 mm, the outermost end rl is preferably in a range of 21 to 23 mm (with the proviso of satisfying rO