DISPLAY APPARATUS AND METHOD [Technical Field] [0001] The present invention relates to a display apparatus and method, and more particularly to a display apparatus and method suitable for display of moving images. [Background Art] [0002] There is a demand for improving the quality of displayed images, as by improving signal processing techniques and driving techniques for image display devices. [0003] In general, the image quality of an image can be improved by increasing the resolution of the image and smoothing the texture thereof. The amount of information of an image is expressed in the unit of pixels indicative of dots (dots) which constitute the image. The number of pixels of an image is expressed by the number of horizontal and vertical dots of the image, such as 800 x 600 or 1024 x 768 . More specifically, the greater the number of pixels (dots), the more smooth the texture of the image and the more the amount of information constituting the image. [0004] To display an image with high resolution, there is a technique (refer to Patent Document 1, for example) which makes it possible to display an image with twice as high resolution in a multi mode compared to a system using only one display, by using, for example, two displays 1 and 2 so as to cause the display 1 to display an image in a normal single mode and so as to cause the respective displays 1 and 2 to display the left and right halves of the image in the multi mode. [0005] [Patent Document 1] Japanese Patent Application Publication No. Hei-10-124024 [0006] If an image is displayed with increased resolution, the amount of information constituting the image increases, so that the amount of data to be transferred to the display 1 or 2 increases and the data transfer rate needs to be increased. For this reason, this system is constructed to perform transfer of image data without increasing the data transfer rate, by reducing the amount of data for each dot of the displays 1 and 2 and performing conversion of the reduced data through signal processing. [0007] In addition, the image quality of a moving image in particular can be improved by increasing a frame rate which is the number of times per second of updating of a screen. [0008] For example, when a moving image is to be projected and displayed on a screen by using a projector, the projector displays a frame image line by line by performing horizontal scan on a line by line basis, and after having scanned all lines of one frame of image, starts scanning image data of the succeeding frame, thereby displaying the moving image. [Disclosure of the Invention] [Problems that the Invention is to Solve] [0009] As mentioned above, the image quality of a moving image in particular can be improved by increasing the frame rate. However, in order to perform display processing according to high frame rates, it is necessary to increase the processing speed of a driving circuit for driving a display device, and furthermore, it is necessary to increase the reaction speed of a light-amount modulation element which determines the intensity of an image. This method is technically difficult, and results in an increase in cost. [0010] Although it is known that the image quality of a moving image can be improved by increasing the frame rate, it is impossible to actually examine the relationship between the frame rate and the image quality of the moving image at increased frame rates. Accordingly, it has not yet been clear whether it is possible to improve the image quality of a moving image to an unlimited extent by increasing the frame rate to an unlimited extent. [0011] As a matter of course, it has been impossible to quantitatively understand the relationship between the frame rate and the moving image at increased frame rate. [0012] For this reason, the present inventor noticed the frame rate of the next generation digital cinema format, and examined its necessary limitations in terms of visual characteristics . [0013] It has heretofore been considered that the speed of a pursuit eye movement which is called smooth pursuit coincides with the moving speed of a visual target. Westheimer has stated that the eyes move at the same speed as the speed of a visual target which is not higher than 30 deg/sec (Westheimer, G., A. M. A. Arch. Ophthal. 52, pp. 932-941, 1954). [0014] However, later researches have demonstrated that the speeds of pursuit eye movements are in almost all cases smaller than the speeds of visual targets. Meyer, et al. have stated that the pursuit speed of the eyes is approximately 0.87 with respect to the speed of a visual target. (Meyer, C. H. et al., Vision Res. Vol. 25, No. 4, pp. 561-563, 1985). [0015] Although Meyer has reported that a maximum pursuit speed limit of 100 deg/sec was obtained, Meyer has stated that such a pur suit speed was a result obtained from ski lied test subjects and general test sub j ects were unable to perform such tracking. The condition of this experiment is a visual distance of 80 cm which greatly differs from the visual environments of movie theaters. The visual target is a light spot which moves by a galvanometer, and Meyer does not discuss the spatial frequency of the visual target. [0016] In Japan, there is a report example of NHK which discusses frame rates (Yasushi Tadokoro, et al., NHK Technical Report, September (1968), pp. 422-426, 1968), but the condition of the report is a 14-inch monitor with a maximum luminance of 30 fl (102.78 cd/m2) at a visual distance of 7H (H: screen height) and still does not allow for cinematic conditions. In addition, the report concludes that a field frequency of 60 Hz or higher is unnecessary for the reason why large motion does not appear in general contents. The conditions of Miyahara's experiment on dynamic visual acuity with respect to vibrating visual targets are a 14-inch monitor, a visual distance of 4H and a maximum luminance of 400 cd/m2. Experiments concerning visual characteristics have been mainly conducted under visual environment conditions such as comparatively short distances and high luminances. [0017] Therefore, the present inventor has conducted experimental examinations on the dynamic spatial frequency characteristics of the eyes in the visual environments of movie theaters, i.e., a maximum luminance of 40 cd/m2 and a visual distance of 5 to 15 m. Research on moving image quality depending on such dynamic spatial frequency characteristics is important because such research leads to a great consideration of conventional formats for frame rates. [0018] In the process of this research, the present inventor has actually examined the relationship between frame rates and moving image quality in higher frame rates and demonstrated human visual characteristics. [0019] The present invention has been made in view of the above-mentioned situations, and intends to make it possible to present a moving image of less degradation to an observer who is a person viewing a displayed moving image, on the basis of human visual characteristics without unnecessarily increasing the frame rate. [Means for Solving the Problems] [0020] A first display apparatus of the present invention is characterized by including display control means for controlling display to cause display means to display a moving image made of not less than 105 frames/sec, and the display means for displaying the moving image made of not less than 105 frames/sec on the basis of control of the display control means, in which a display of each pixel on a screen is maintained during each frame period. [0021] The display control means controls display to cause the display means to display a moving image made of not less than 230 frames/sec, and the display means is capable of displaying the moving image made of not less than 230 frames/sec on the basis of control of the display control means. [0022] The display control means controls display to cause the display means to display a moving image made of not larger than 480 frames/sec, and the display means is capable of displaying the moving image made of not larger than 480 frames/sec on the basis of control of the display control means . [0023] The display control means controls display to cause the display means to display a moving image made of 120 frames/sec, and the display means is capable of displaying the moving image made of 120 frames/sec on the basis of control of the display control means. [0024] The display control means controls display to cause the display means to display a moving image made of 240 frames/sec, and the display means is capable of displaying the moving image made of 240 frames/sec on the basis of control of the display control means. [0025] The display control means controls display to cause the display means to display a moving image made of 250 frames/sec, and the display means is capable of displaying the moving image made of 250 frames/sec on the basis of control of the display control means. [0026] The display control means controls display to cause the display means to display a moving image made of 360 frames/sec, and the display means is capable of displaying the moving image made of 360 frames/sec on the basis of control of the display control means. [0027] A first display method of the present invention is a display method for a display apparatus equipped with display means in which a display of each pixel on a screen is maintained during each frame period, and is characterized by including a display control step of controlling display to cause the display means to display a moving image made of not less than 105 frames/sec. [0028] In the display control step, display is controlled to cause the display means to display a moving image made of not less than 230 frames/sec. [0029] In the display control step, display is controlled to cause the display means to display a moving image made of not larger than 480 frames/sec. [0030] In the display control step, display is controlled to cause the display means to display a moving image made of 120 frames/sec. [0031] In the display control step, display is controlled to cause the display means to display a moving image made of 240 frames/sec. [0032] In the display control step, display is controlled to cause the display means to display a moving image made of 250 frames/sec. [0033] In the display control step, display is controlled to cause the display means to display a moving image made of 360 frames/sec. [0034] A second display apparatus of the present invention is characterized by including display control means for controlling display to cause display means to display a moving image made of not less than 105 frames/sec, and the display means for displaying the moving image made of not less than 105 frames/sec on the basis of control of the display control means, the display means being matrix-driven. [0035] The display control means controls display to cause the display means to display a moving image made of not less than 230 frames/sec, and the displaymeans is capable of displaying the moving image made of not less than 230 frames/sec on the basis of control of the display control means. [0036] The display control means controls display to cause the display means to display a moving image made of not larger than 480 frames/sec, and the display means is capable of displaying the moving image made of not larger than 480 frames/sec on the basis of control of the display control means . [0037] The display control means controls display to cause the display means to display a moving image made of 12 0 frames/sec, and the displaymeans is capable of displaying the moving image made of 120 frames/sec on the basis of control of the display control means. [0038] The display control means controls display to cause the display means to display a moving image made of 240 frames/sec, and the display means is capable of displaying the moving image made of 240 frames/sec on the basis of control of the display control means. [0039] The display control means controls display to cause the display means to display a moving image made of 250 frames/sec, and the display means is capable of displaying the moving image made of 250 frames/sec on the basis of control of the display control means. [0040] The display control means controls display to cause the display means to display a moving image made of 360 frames/sec, and the display means is capable of displaying the moving image made of 360 frames/sec on the basis of control of the display control means. [0041] A second display method of the present invention is a display method for a display apparatus equipped with matrix-driven display means, and is character! zed by including a display control step of controlling display to cause the display means to display a moving image made of not less than 105 frames/sec. [0042] In the display control step, display is controlled to cause the display means to display a moving image made of not less than 230 frames/sec. [0043] In the display control step, display is controlled to cause the display means to display a moving image made of not larger than 480 frames/sec. [0044] In the display control step, display is controlled to cause the display means to display a moving image made of 120 frames/sec. [0045] In the display control step, display is controlled to cause the display means to display a moving image made of 240 frames/sec. [0046] In the display control step, display is controlled to cause the display means to display a moving image made of 250 frames/sec. [0047] In the display control step, display is controlled to cause the display means to display a moving image made of 360 frames/sec. [0048] In the first display apparatus and the first display method according to the present invention, display is controlled to cause the display means in which the display of each pixel on the screen is maintained during each frame period to display a moving image made of not less than 105 frames/sec. [0049] In the second display apparatus and the second display method according to the present invention, display is controlled to cause the matrix-driven display means to display a moving image made of not less than 105 frames/sec. [Advantage of the Invention] [0050] As mentioned above, according to the present invention, it is possible to present a moving image of less degradation to an observer who is a person viewing a displayedmoving image, on the basis of human visual characteristics without unnecessarily increasing the frame rate. [Brief Description of the Drawings] [0051] [Fig. 1] A block diagram for explaining a first construction example of an image display system to which the present invention is applied. [ Fig. 2 ] A diagram for explaining the timing of an input video signal and output video signals. [Fig. 3] A view for explaining a construction example of the image display device shown in Fig. 1. [Fig. 4] A diagram for explaining the rate of updating of an edge section of a moving image displayed on the image display device shown in Fig. 3. [Fig. 5] A flowchart for explaining a display control process 1 to be executed by the image display system shown in Fig. 1. [Fig. 6] A block diagram for explaining a second construction example of the image display system to which the present invention is applied. [Fig. 7] A flowchart for explaining a display control process 2 to be executed by the image display system shown in Fig. 6. [Fig. 8] A diagram for explaining the timing of an input video signal and output video signals. [Fig. 9] A view showing an example of an actual scene in which a moving object and a stationary object exist together. [Fig. 10] A view for explaining a fixation condition. [Fig. 11] A view for explaining a tracking condition. [Fig. 12] A view for explaining recognition by an observer during tracking and fixation. [Fig. 13] A view for explaining recognition by the observer under image capture conditions, under display condition and under observation conditions. [Fig. 14] A view for explaining strobe artifacts. [Fig. 15] A view for explaining recognition by the observer at a high frame rate under image capture conditions, under display condition and under observation conditions. [Fig. 16] A view for explaining the result of evaluation of moving image quality in terms of jerkiness. [Fig. 17] A view for explaining the result of evaluation of moving image quality in terms of motion blur. [Fig. 18] A view for explaining a construction example of projectors and a screen, where n is a number except 2. [Fig. 19] A view for explaining the timing of an input video signal and output video signals, where m = 240 and n = 4 [Fig. 20] A view for explaining the timing of an input video signal and output video signals, where m = 250 and n = 5. [Fig. 21] A view for explaining the construction of an image display system 101 using an LCD. [Description of Reference Numerals] l...image display system, 11...image signal conversion device, 12...image display device, 21...A/D conversion section, 22...synchronizing signal detection section, 23...frame memory, 24...controller, 25...D/A conversion section, 27...display control section, 41...scan control section, 43...display section, 71...image display system, 81...image signal conversion section, 91...data separation section, 92...data holding section, 94...controller, 93...frame memory, 101...image display system, 111...signal processing section, 112...clock/sampling pulse generation section, 113...image display device, 121...Y/C separation/chroma decoding section, 122..A/D conversion section, 124...synchronizing signal detection section, 125...control signal generation section, 131...LCD, 133-1 to 133-4...data line driving circuits, 134...gate line driving section, 141...liquid crystal cell, 142...TFT, 143...capacitor. [Best Mode for Carrying Out the Invention] [0053] Embodiments of the present invention will be described below with reference to the accompanying drawings. [0054] Fig. 1 is a block diagram showing the construction of an image display system 1 to which the present invention is applied. The image display system 1 includes an image signal conversion device 11 and an image display device 12 . The image display system 1 is constructed to be supplied with an analog image signal corresponding to amoving image, process the image signal in the image signal conversion device 11, and supply the processed image signal to the image display device 12 so that the moving image is displayed. [0055] The analog image signal supplied to the image signal conversion device 11 is supplied to an A/D conversion section 21 and a synchronizing signal detection section 22. [0056] The A/D conversion section 21 converts the analog image signal having a frame rate m into a digital image signal, and supplies the digital image signal to a frame memory 23. The synchronizing signal detection section 22 detects the frame rate and the dot clock of the image signal from the image signal, and generates a vertical synchronizing signal and a dot clock signal and supplies the vertical synchronizing signal and the dot clock signal to a controller 24. The dot clock is the reciprocal of the time required to display one dot on a display. [0057] The controller 24 is supplied with the vertical synchronizing signal and the dot clock signal from the synchronizing signal detection section 22, and controls outputting of a video signal from the frame memory 23 and supplies information associated with the outputting of the video signal from the frame memory 23 to a display control section 27. The frame memory 23 outputs the supplied digital image signal to a D/A converter section 25-1 or a D/A conversion section 25-2 on the basis of the control of the controller 24. [0058] The inputting and outputting of video signals to and from the frame memory 23 under the control of the controller 24 will be described below with reference to Fig. 2. [0059] It is assumed that m denotes the frame rate of an input video signal SI inputted to the frame memory 23. It is also assumed that frames sequentially inputted to the frame memory 23 are an a frame, an