DESCRIPTION INPUT DEVICE FOR ELECTRONIC APPARATUS Technical Field [0001] The present invention relates to an input device for an electronic apparatus usable for input operation of an electronic apparatus such as a cellular phone terminal, a personal digital assistant (PDA), a portable music player, or a portable video game machine. Background Art [0002] For the purpose of improving operability for a user or reducing the number of mechanical operation buttons, recently, touch panels are often adopted for various electronic units for input operation by a user. Such a touch panel includes a display unit that can display various types of Information and a touch sensor for detecting a contact position of a user's finger or a fine-tipped pen (a stylus) on the display. Then, an object such as a button which can be operated is displayed on the display unit as visible Information and a display position of each object and a position detected by the touch sensor are made to correspond and input processing is carried out. That is, if a user touches a position of a specific object displayed on the display unit by a finger etc, the electronic apparatus recognizes that the position detected by the touch sensor matches the position of the object and the electronic apparatus carries out a function allocated to the object. Thus, a number of mechanical operation buttons do not need to be provided. Moreover, it becomes possible to freely change the position, number, shape, or the like of the operation button by changing Information indicating the correspondence relationship between the content of the object displayed on the display unit, the position of each object, and coordinates on the touch panel without making a change to the hardware. [0003] Meanwhile, because the size of a portable terminal such as a cellular phone terminal is relatively small, the size of the display unit to be mounted thereon is also small. Therefore, displaying a number of objects to which different functions are respectively allocated in order to enable various input operations by the user, display size of each object must be set small. [0004] Even in a case where a relatively smaller object is operated, when a fine-tipped pen is used, it is relatively easier to distinguish and operate each object. However, if a user touches the display to operate the object by a finger, it is difficult to operate a small-sized object. For example, an object which is an operation target is hidden by a finger and cannot be seen by the user and if a space between adjacent objects is narrow, there is a possibility that a plurality of objects would be touched simultaneously by the same finger and therefore an incorrect operation is prone to occur. [0005] Further, in a case where such a portable terminal is operated, such a situation can be assumed wherein a user holds the apparatus main body with one hand, and operates the respective objects displayed on the screen by one hand in a manner of moving hls/her thumb or another finger of the holding hand. However, to operate the apparatus by use of a pen as mentioned above, the user must use both hands and therefore operability in such a case is not very good. Accordingly, it is preferable that the apparatus can be operated without incorrect operations by use of only a finger of the user without using a pen. [0006] For example, the Patent Document 1 discloses a conventional art for correctly and easily specifying a selection item (equivalent to an object) even in a case where a user operates selection items displayed with narrow display space by a finger. In the Patent Document 1, it is suggested that a pointer corresponding to the operation position is displayed in a position distant by a predetermined distance from a position on the display where a finger touched. Accordingly, because a selection item is specified by indirect operation via a pointer displayed in a position not hidden by a finger, operability can be improved. [0007] Moreover, a conventional art regarding the shape of a pointer in a case where a similar pointer is operated by a pen tip is disclosed in the Patent Document 2. In the Patent Document 2, the shape of a pointer is configured by combination of a round area for being touched by the pen and an arrow-shaped area to enable more accurate position designation when a pen is used. [0008] Moreover, a conventional art with regard to pointer operation is disclosed in the Patent Document 3. The Patent Document 3 suggests distinguishing and receiving two types of operation, operation for displaying and moving the pointer and click operation. Patent Document 1: JP-A-6-51908 Patent Document 2: JP-A-6-161665 Patent Document 3: JP-A-2000-267808 Disclosure of the Invention Objects to be Solved by the Invention [0009] If the pointer is displayed on a screen and an object is operated indirectly by use of the pointer as described in the Patent Documents 1, 2, and 3, operability can be improved in a case where a small-sized object is operated by a finger. [0010] However, in a case where the pointer is used, it is necessary to separately carry out operation to move the pointer to determine the position thereof and the operation to select (to click) as in the Patent Document 3. Therefore, there is a problem that the operation becomes more complicated compared to a case where each object is directly operated by a finger. For example, in such a situation that an object such as an operation button displayed on a screen is large enough, there is a case where the operation can be carried out efficiently with fewer operation procedures if the object is directly operated by a finger without using a pointer compared to a case where the pointer is used. Moreover, there is another problem that if the pointer is displayed, a part of the displayed content on the screen is hidden by the displayed pointer or is overlapped with the pointer and therefore the displayed pointer may obstruct operation by the user in a case where there is no need to use a pointer. [0011] The present invention has been made in consideration of the above-mentioned circumstances, and a purpose thereof is to provide an input device for an electronic apparatus which can improve operability even in a case where a user carries out input operation by use of a touch panel and an operation target is small or the like, and enables efficient input operation by the user in various situations. Means for Solving the Object [0012] An input device for an electronic apparatus according to the present invention includes a display unit that can display visible Information regarding an input operation, an input operation unit that includes a touch panel having an input function by a touch operation on an input screen corresponding to a display screen of the display unit, an input control unit that instructs a processing based on input signals from the input operation unit, an operation object display control unit that displays at least one operation object as visible Information indicating an operation target portion for instructing execution of a specific function on the display unit as the visible Information via the input operation unit, and a pointer display control unit that has a function to display a pointer being movable on the display screen for carrying out input of an instruction to the operation object via the input operation unit on the display unit as the visible Information, displays or hides the pointer in accordance with the Information of the operation object displayed on the display unit, and displays the pointer in a case where a width or a size of the display area of the operation object displayed on the display unit or a width or a size of an area for receiving the input operation is equal to or smaller than a predetermined value as Information of the operation object. Thus, the pointer is displayed in response to Information of the operation object, in a case where the width or the size of the display area of the operation object displayed on the display unit or the area for receiving the input operation is equal to or smaller than the predetermined value, therefore a user can operate the operation object by the pointer. In this case, an indirect operation by the pointer is enabled in a condition where a direct operation using the touch panel is not easy due to the small operation object and operability can be improved. Therefore, the pointer can be displayed and made available as necessary corresponding to the situation of the display screen and operational efficiency or convenience can be improved. [0013] Moreover, the present invention is the input device for the electronic apparatus wherein the pointer display control unit displays the pointer in a case where a contact area on the input screen of the input operation unit a during touch operation is equal to or greater than a predetermined value. Thus, in a case where the contact area on the input screen of the input operation unit during the touch operation is equal to or greater than the predetermined value, it is regarded that a user is operating the touch panel by his/her finger and the pointer is displayed to enable direct operation by the pointer. Moreover, if the contact area is smaller than the predetermined value, it is regarded that the user is operating by use of a stylus having a fine tip or the like and the pointer can be hidden. Therefore, unnecessary display of the pointer can be inhibited. Thus, displaying/hiding of the pointer can be switched as necessary. [0014] Further, the present invention is the input device for the electronic apparatus wherein the pointer display control unit sets a display position of the pointer in the vicinity of an area including an operation object corresponding to a display condition of the pointer, and the display position of the pointer does not overlap the operation object when displaying the pointer. Thus, the pointer can be displayed in an appropriate position that does not obstruct display or operation of the operation object in an initial condition of a pointer display or the like. [0015] Further, the present invention is the input device for the electronic apparatus, wherein the input control unit can receive input signals by either input operations such as direct operation to the operation object on the display screen or indirect operation to the operation object on the position of the pointer as the input operation corresponding to the display screen of the display unit. Thus, both the direct operation to the operation object and the indirect operation to the operation object using the pointer can be carried out. Therefore, it becomes possible to carry out either the direct operation or the indirect operation corresponding to the situation. Therefore, an efficiënt input operation by a user in various situations is enabled and operational efficiency can be improved. [0016] Further, the present invention is the input device for the electronic apparatus, wherein the pointer display control unit sets a first condition wherein the indirect operation to the operation object by the pointer is invalid and a second condition where the indirect operation to the operation object by the pointer is valid when displaying the pointer, and switches the first condition and the second condition in accordance with a detection situation of the input operation to the pointer. Thus, it becomes possible to switch respective valid/invalid conditions of indirect operation by the pointer depending on the input operation situation to the pointer and occurrence of unintended incorrect operation by the user can be inhibited. [0017] Further, the present invention is the input device for the electronic apparatus, wherein the pointer display control unit displays the pointer switching display mode of the pointer in accordance with the first condition and the second condition. Thus, it becomes possible to easily recognize the condition of the pointer, prevent occurrence of an incorrect operation, and improve visibility or operability. [0018] Further, the present invention is the input device for the electronic apparatus, wherein the pointer display control unit adds a selection display indicating that an operation object at the display position of the pointer or in the vicinity of the display position of the pointer is selected by the pointer in a case where the pointer is in the second condition. Thus, the condition of the pointer or the selection condition of the operation object can be easily recognized and visibiiity or operability can be improved. [0019] Further, the present invention is the input device for the electronic apparatus, wherein the pointer display control unit uses character patterns, whose form can be changed, as the pointer and carries out animation display of the character pattern. Thus, the user can intuitively understand the current operation condition such as moving by the change in form of the pointer and efficiënt input operation by use of the pointer is enabled. Moreover, it is also possible to improve usability providing the pointer display with an amusement factor. [0020] Further, the present invention is the input device for the electronic apparatus, wherein the pointer display control unit changes a form including at least either a shape or a size of the pointer corresponding to a form of the contact area in the input screen of the input operation unit during the touch operation. Thus, it is possible to display the pointer having an appropriate form corresponding to the size or shape of the contact area of each user, and visibiiity or operability can be improved. [0021] Further, the present invention provides an electronic apparatus mounted with any of the above-mentioned input devices. Effects of the Invention [0022] According to the present invention, in a case where a user carries out input operation by use of a toucli panel, operability can be improved even when an operation target is small or the like and it becomes possible to provide an input device for an electronio apparatus which enables efficiënt input operation by a user in various situations. Brief Description of the Drawings [0023] [FIG. 1] A block diagram showing configuration of a main body of an input device for an electronio apparatus according to an embodiment of the present invention. [FIG. 2] A view showing an example of display content on a display screen of the input device according to the embodiment. [FIG. 3] A view showing a specific example of operation procedures by a user to the display screen of the input device according to the embodiment. [FIG. 4] A sequence diagram showing performance with regard to display control of a virtual stylus in the input device according to a first embodiment. [FIG. 5] A sequence diagram showing performance with regard to reception of input operation in a virtual stylus display condition in the input device according to the first embodiment. [FIG. 6] A view showing an example of display content on the display screen and performance in response to operation by a user in the input device according to a second embodiment. [FIG. 7] A view showing transition of condition of a virtual stylus displayed on the display. [FIG. 8] A flowchart showing processing procedures in the input operation to the virtual stylus in the input device according to the second embodiment. [FIG. 9] A sequence diagram showing performance with regard to reception of input operation in a virtual stylus display condition in the input device according to the second embodiment. [FIG. 10] A schematic view showing a difference in operation positions corresponding to a judgment result of direct or indirect operation. [FIG. 11] A view showing an example of display content on the display and performance in response to operation by a user in the input device according to a third embodiment. [FIG. 12] A sequence diagram showing performance with regard to reception of input operation in a pointer display condition in the input device according to the third embodiment. Description of Reference Numerals [0024] 10 Display unit 11, 11A to 11M Display screen 12 Operation object 13 Virtual stylus 13a Main area 13b Projection area 14 Finger 20 Touch panel 30 Screen data storing unit 50 Pointer 51a, 51bSelection display 60 Processing target 100 Application 200 Screen generation unit 210 l\/linute operation judgement unit 300 Screen display control unit 310 Virtual stylus display control unit 400 Input signal analysis unit 410 Virtual stylus condition management unit 500 Input signal control unit Best Mode for Carrying Out the Invention [0025] in the following embodiments, a configuration example in which an input device for an eiectronic apparatus is applied as an example to a mobile electronic apparatus such as a cellular phone terminal is shown. [0026] (First embodiment) FIG. 1 is a block diagram showing a configuration of a main body of an input device for an electronic apparatus according to a first embodiment of the present invention. [0027] The input device of the present embodiment is a device which is assumed to be used by a user to carry out input operation to an electronic apparatus such as a cellular phone terminal, a personal digital assistant (PDA), a portable music player, or a portable video game machine. The input device is mounted on the electronic apparatus and includes a touch panel having an input function by touch operation such as touching or tracing on an input screen on a display unit. [0028] An input device 1 shown in FIG. 1 includes a display unit 10, a touch panel 20, a screen data storing unit 30, an application 100, a screen generation unit 200, a minute operation presence/absence judgment unit 210, a screen display control unit 300, a virtual stylus display control unit 310, an input signal analysis unit 400, a virtual stylus condition management unit 410, and an input signal control unit 500. [0029] The application 100, the screen generation unit 200, the minute operation presence/absence judgment unit 210, the screen display control unit 300, the virtual stylus display control unit 310, the input signal analysis unit 400, the virtual stylus condition management unit 410, and the input signal control unit 500 respectively include a program carried out by a micro computer for controlling (not shown) or a dedicated control circuit. Moreover, the eiectronic apparatus mounted with the input device 1 includes a processing target 60 for carrying out processing by control carried out by the application 100 or the like in response to the input operation to the input device 1. The processing target 60 includes various elements provided for an eiectronic apparatus such as a display unit for carrying out various types of displays, an amplifier for outputting a sound signal, a program for reproducing content, and a setting control unit for carrying out various types of settings of the apparatus. [0030] The display unit 10 is a device which can display various visible Information such as a text, a graphic, and an image on a flat display and includes a liquid crystal display unit or the like. The touch panel 20 is an input device for operation which is provided in a laminated manner on the display screen of the display unit 10 and includes a transparent sheet-like member formed to be flat, and the sheet-like member forms the input screen. The touch panel 20 has a function of an input operation unit and periodically outputs a signal indicating contact on the input screen and coordinate information of a position at which the contact is detected. Therefore, when a user presses down on (touches) the input screen of the touch panel 20 by use of the user's own finger, a stylus pen, or the lil