JP2012123085A - Multi-screen display apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-screen display apparatus in which unevenness in brightness and color may be easily and accurately corrected in each screen and among screens of a multi-screen composed of a plurality of screens.SOLUTION: Screens 20 of a plurality of image display devices 1 are combined for obtaining a multi-screen, so as to construct a multi-screen display apparatus for displaying images in the multi-screen. Each image display device 1 corrects a brightness value by an image processing circuit 4a so that uneven brightness may be corrected in the screen 20 on the basis of information on brightness of a center and a peripheral portions of the screen 20 stored in a memory circuit 4c. Subsequently, the plural image display devices 1 communicate with one another for informing the corrected brightness values, and a target brightness value corresponding to a target of the whole multi-screen is obtained on the basis of these brightness values. The image processing circuit 4a of each image display device 1 further corrects the brightness value on the basis of the thus obtained target brightness value.

Description

  The present invention relates to a multi-screen display device that displays a video by composing one screen by combining the screens of a plurality of video display devices.

  The multi-screen display device is a device that displays a video by composing one screen by combining the screens of a plurality of video display devices. Examples of the video display device constituting the multi-screen display device include a projection video display device and a liquid crystal video display device.

  A projection-type image display device displays an image on a screen by projecting an image from the back of a screen using a lamp or a light emitting diode (abbreviation: LED) as a light source. The liquid crystal image display device displays an image on a screen by using a fluorescent tube or an LED as a backlight and irradiating the liquid crystal device with light from the backlight.

  Irradiation unevenness occurs when the screen is irradiated with light in any of the projection type video display device and the liquid crystal video display device. This uneven irradiation causes uneven brightness and color in the screen. Specifically, there is a tendency that the center of the screen is bright and the periphery is dark.

  A plurality of such screens with uneven brightness and uneven colors are combined to form a display screen of a multi-screen display device (hereinafter sometimes referred to as “multi-screen”). Therefore, in multi-screen display devices, individual differences in brightness and color at the center of the screen that occur in each video display device, as well as individual differences in brightness and color at adjacent screen edges, are factors that impair the sense of unity in the multi-screen. ing.

  Patent Literature 1 and Patent Literature 2 disclose techniques for correcting luminance unevenness and color unevenness in each screen in a multi-screen display device, and luminance unevenness and color unevenness between screens. In the technology disclosed in Patent Document 1, after installing a multi-screen display device, luminance unevenness and color unevenness are visually corrected between screens and between screens, or a measuring instrument such as a camera or a luminance meter is used. A correction value is calculated, and luminance unevenness and color unevenness within and between screens are corrected.

  Further, in the technique disclosed in Patent Document 2, after correcting the luminance unevenness and color unevenness in the screen and between the screens, the luminance unevenness and color unevenness between the screens due to a change in the light amount of the light source or the backlight or the like. Is corrected by measuring the amount of light with a luminance sensor arranged in the video display device.

Japanese Patent No. 3287007 (page 18, FIG. 12) Japanese Patent Laid-Open No. 10-90645 (page 6, FIG. 1)

  In the correction by visual inspection or measuring instrument after installing the multi-screen display device as disclosed in Patent Document 1, it takes a lot of time for measurement and adjustment, and depending on the installation location and the number of screens constituting the multi-screen. However, there is a problem that the use of the measuring instrument and the visual adjustment may be difficult.

  In the technique disclosed in Patent Document 2, the entire screen of each video display device is corrected with a uniform correction amount based on the measurement result of the luminance at the center of the screen by the luminance sensor. The brightness unevenness and color unevenness of the image can be suppressed, but the optimum correction around the screen cannot be achieved. Therefore, there is a problem that the luminance unevenness and the color unevenness at the screen edge of the adjacent video display device may not be suppressed in the multi-screen display device.

  An object of the present invention is to provide a multi-screen display capable of easily and accurately correcting luminance unevenness and color unevenness in each screen in a multi-screen composed of a plurality of screens, and luminance unevenness and color unevenness between screens. Is to provide a device.

  A multi-screen display device of the present invention is a multi-screen display device that includes a plurality of video display devices and displays video based on video signals on a multi-screen configured by combining the screens of the plurality of video display devices. The plurality of video display devices are communicably connected, and each video display device relates to central luminance information relating to the luminance of the central portion of the screen of the video display device, and luminance of peripheral portions surrounding the central portion. Storage means for storing peripheral luminance information, and the video signal so that luminance unevenness in the screen of the video display device is corrected based on the central luminance information and the peripheral luminance information stored in the storage means And a correction unit that corrects a luminance value included in the video, and a video that is predetermined as a master device that controls another video display device among the plurality of video display devices. The correction unit of the display device acquires (a) the luminance value corrected by the correction unit of another video display device, and (b) the acquired luminance value and a video display predetermined as the master device. Based on the brightness value corrected by the correcting means of the apparatus, a target brightness value that is a target of the entire multi-screen is obtained, and (c) the obtained target brightness value is transmitted to the other video display device. Then, based on the obtained target luminance value, the luminance value corrected by the correction unit of the video display device predetermined as the master device is corrected, and the correction unit of the other video display device is the master device. When the target luminance value is received from the correction unit of the video display device determined in advance as follows, the correction unit of the video display device corrects based on the received target luminance value. And corrects the luminance value.

  According to the multi-screen display device of the present invention, a multi-screen display device is configured by including a plurality of video display devices, and a multi-screen is configured by combining the screens of the plurality of video display devices. Video is displayed on the multi-screen based on the video signal. In each video display device, the luminance value included in the video signal is corrected based on the central luminance information and the peripheral luminance information stored in the storage means so that the luminance unevenness in the screen of the video display device is corrected. It is corrected by. As a result, it is possible to easily and accurately correct the luminance unevenness in each screen constituting the multi-screen.

  Among the plurality of video display devices, another video display device is controlled by a video display device that is predetermined as a master device. The brightness value corrected by the correcting means of another video display device is acquired by the correcting means of the master device. Based on the acquired luminance value and the luminance value corrected by the correcting means of the master device, the target luminance value of the entire multi-screen is obtained and transmitted to another video display device. Further, the luminance value corrected by the correcting means of the master device is corrected based on the obtained target luminance value. In another video display device, the luminance value corrected by the correction unit of the video display device is corrected based on the target luminance value received from the correction unit of the master device. This makes it possible to easily and accurately correct luminance unevenness between a plurality of screens constituting a multi-screen.

  Therefore, it is possible to provide a multi-screen display device that can easily and accurately correct luminance unevenness within each screen and between screens. In addition, by correcting the luminance unevenness for each color, the multi-screen can easily and accurately correct the luminance unevenness and the color unevenness in each screen and the luminance unevenness and the color unevenness between the screens. A screen display device can be provided.

It is a block diagram which shows the structure of the projection type video display apparatus 1 which is one of the video display apparatuses used in the multi-screen display apparatus which is the 1st Embodiment of this invention. It is a figure which shows typically the brightness nonuniformity in the screen 20 of the screen 2, and the color nonuniformity. It is a figure which shows typically an example of the brightness nonuniformity and the color nonuniformity in the multiscreen 21 of the multiscreen display apparatus comprised combining four video display apparatuses 1. FIG. It is a graph showing the video signal level with respect to the screen horizontal coordinate before a gain adjustment process, and the brightness | luminance in a screen. It is a graph showing the video signal level with respect to a screen horizontal coordinate after gain adjustment processing, and the brightness | luminance in a screen. It is a graph showing the video signal level with respect to the screen horizontal coordinate after performing a gradation correction process, and the brightness | luminance in a screen. 4 is a diagram for explaining a method of measuring luminance data in the manufacturing stage of the video display device 1. FIG. It is a figure which shows typically the multi-screen display apparatus 10 which combined four video display apparatuses 1a, 1b, 1c, 1d. 5 is a flowchart showing a processing procedure of luminance unevenness and color unevenness correction processing in the master video display device 1. 6 is a flowchart showing a processing procedure of luminance unevenness and color unevenness correction processing in the slave video display device 1; It is a graph showing the video signal level and the brightness | luminance in a screen with respect to the screen horizontal coordinate after the gradation correction process in case the time-dependent change of the light quantity of the light source 3c has not arisen. It is a graph showing the video signal level and the brightness | luminance in a screen with respect to the screen horizontal coordinate after the gradation correction process in case the temporal change of the light quantity of the light source 3c has arisen.

<First Embodiment>
FIG. 1 is a block diagram showing a configuration of a projection type video display device 1 which is one of video display devices used in the multi-screen display device according to the first embodiment of the present invention. In the following description, the “projection-type video display device” may be simply referred to as “video display device”. The video display device 1 includes a screen 2, a projection unit 3, and an electric circuit unit 4.

  The projection unit 3 includes a video display device 3a, a condenser lens 3b, a light source 3c, a projection lens 3d, and a luminance sensor 3e. The electric circuit unit 4 includes a video processing circuit 4a, a microcomputer (hereinafter referred to as “microcomputer”) circuit 4b, a memory circuit 4c, and a video input circuit 4d.

  The video input circuit 4 d is connected to a video source 5 disposed outside the video display device 1. The video signal output from the video source 5 is input to the video input circuit 4d. The video input circuit 4d converts the input video signal into a digital signal. The video input circuit 4d gives the video signal converted into a digital signal (hereinafter sometimes referred to as “digital video signal”) to the video processing circuit 4a.

  The video processing circuit 4a performs processing for adjusting the image quality of the video represented by the digital video signal (hereinafter sometimes referred to as “image quality adjustment processing”) on the digital video signal supplied from the video input circuit 4d. Thereafter, the video processing circuit 4a converts the digital video signal after the image quality adjustment processing into a digital signal format required by the video display device 3a of the projection unit 3, and gives the digital signal to the video display device 3a. The video processing circuit 4a corresponds to correction means.

  The light emitted from the light source 3c is uniformly dispersed through the condenser lens 3b and irradiated to the video display device 3a. The video display device 3a modulates the light emitted from the light source 3c based on the digital video signal provided from the video processing circuit 4a to generate video light. The video display device 3a projects the generated video light onto the surface of the screen 2 via the projection lens 3d. As a result, the image light projected by the projection lens 3d is irradiated onto the surface of the screen 2, and an image represented by the digital image signal is displayed.

  A portion of the surface of the screen 2 where an image is displayed is referred to as a screen 20 of the image display device 1. In the present embodiment, the entire surface of the screen 2 is the screen 20. On this screen 20, video is displayed based on the video signal as described above. The video display device 3a is realized by, for example, a digital mirror device (abbreviation: DMD).

  The video processing circuit 4a applies the three primary colors of light red (Red; abbreviation: R), green (Green; abbreviation: G), blue (Blue; abbreviation: B) to the digital video signal given from the video input circuit 4d. Image quality adjustment processing is performed independently for each time. In this way, the video processing circuit 4a performs image quality adjustment processing for each color on the digital video signal.

  As image quality adjustment processing, for example, processing for increasing / decreasing the signal level of the entire screen (hereinafter also referred to as “gain adjustment processing”) and processing for increasing / decreasing the signal level for each area in the screen (hereinafter “gradation correction processing”). In some cases). In the present embodiment, as gradation correction processing, processing for increasing / decreasing the signal level is performed for each of a total of eight areas including the top, bottom, left and right edges and four corners of the screen.

  The signal level of the digital video signal corresponds to a luminance value included in the digital video signal. Performing the image quality adjustment process, specifically, increasing or decreasing the signal level by the gain adjustment process and the gradation correction process corresponds to correcting the luminance value. Therefore, performing the image quality adjustment process for each color on the digital video signal as described above corresponds to correcting the luminance value included in the digital video signal for each color.

  The microcomputer circuit 4 b is connected to an external control device 6 disposed outside the video display device 1. The microcomputer circuit 4b is controlled by the external control device 6. The microcomputer circuit 4b writes control data including adjustment values (hereinafter, also referred to as “image quality adjustment values”) in the image quality adjustment process performed by the video processing circuit 4a to the memory circuit 4c, and the memory circuit 4c performs the control. Process to read data. The memory circuit 4c corresponds to storage means.

  Of the light emitted from the light source 3c, uniformly dispersed through the condenser lens 3b and irradiated onto the video display device 3a, the light that is not projected onto the screen 2 (hereinafter sometimes referred to as “unnecessary light”) It is guided to the luminance sensor 3e by the display device 3a. The luminance sensor 3e measures the amount of light emitted from the light source 3c (hereinafter referred to as “light amount”) by measuring unnecessary light. The luminance sensor 3e corresponds to a measuring unit. The luminance sensor 3e gives data (hereinafter referred to as “light amount data”) representing the measured light amount as a measurement result to the microcomputer circuit 4b. The microcomputer circuit 4b artificially monitors the light amount projected on the screen 2 based on the light amount data given from the luminance sensor 3e.

  FIG. 1 shows an example in which the light amount of the light source 3c is measured by measuring unnecessary light that is not projected onto the screen 2 by the luminance sensor 3e in the video display device 3a. When the video display device 1 is realized by a liquid crystal video display device, the light from the backlight as the light source may be directly measured by the luminance sensor 3e.

  Ideally, the light projected onto the screen 2 should be uniform over the entire area of the screen 20, but actually the light is in the order of the light source 3 c, the condenser lens 3 b, the video display device 3 a, the projection lens 3 d, and the screen 2. In the process of being guided, the central part of the luminous flux becomes the maximum light quantity, and the light quantity decreases as it goes from the central part to the peripheral part. That is, in the screen 2, the central portion of the screen 20 is brightest, and the peripheral portion of the screen 20 is darker than the central portion of the screen 20.

  Such uneven brightness in the screen 20 of the screen 2 is referred to as “brightness unevenness”. In addition, the difference in luminance unevenness for each of the three primary colors R, G, and B is referred to as “color unevenness”.

  FIG. 2 is a diagram schematically showing uneven brightness and uneven color on the screen 20 of the screen 2. FIG. 2 shows an example of the luminance curve when the luminance unevenness and the color unevenness are based on the horizontal coordinate and the vertical coordinate of the screen 20. In FIG. 2, a luminance curve is shown for each of R, G, and B. As shown in FIG. 2, in many cases, the luminance decreases from the central portion S0 of the screen 20 toward the peripheral portion S1, and particularly at the end portion of the screen 20, the luminance tends to decrease rapidly. Further, there are many differences in the way of reduction for each of R, G, and B.

  FIG. 3 is a diagram schematically illustrating an example of luminance unevenness and color unevenness in the multi-screen 21 of the multi-screen display device configured by combining the four video display devices 1. The multi screen 21 is a display screen of a multi screen display device. In the example illustrated in FIG. 3, the multi-screen 21 is configured as one screen by combining the screens 20 of the screens 2 of the four video display devices 1. The multi-screen display device displays the video based on the video signal on the multi-screen 21 by displaying the video based on the video signal on the screen 20 of each video display device 1 as described above.

  In FIG. 3, in order to distinguish the screens 2 of the four video display devices 1, subscripts “a”, “b”, “c”, “d” are added to the reference numeral “2” of the screen, and 1 screen 2a, 2nd screen 2b, 3rd screen 2c, and 4th screen 2d are shown. Further, in order to distinguish the screen 20 of each screen 2, the subscripts “a”, “b”, “c”, and “d” are added to the reference numeral “20” of the screen, and the first screen 20a, the second screen 20 A screen 20b, a third screen 20c, and a fourth screen 20d are shown. In the example shown in FIG. 3, the peripheral portion Sb of the second screen 20b and the peripheral portion Sc of the third screen 20c are darker than the peripheral portion Sa of the first screen 20a and the peripheral portion Sd of the fourth screen 20d.

  As shown in FIG. 2 described above, when there is one screen 20, the user often sees the central portion S 0 of the video displayed on the screen 20, specifically, the central portion S 0 of the screen 20. The luminance unevenness and color unevenness of the peripheral portion S1 are not so noticeable. However, when the multi-screen 21 is configured by combining a plurality of screens 20a, 20b, 20c, and 20d as shown in FIG. 3, the joint portion of the first to fourth screens 20a, 20b, 20c, and 20d is the center of the multi-screen 21. Part. Therefore, the luminance unevenness and the color unevenness of the peripheral portions Sa, Sb, Sc, Sd in the screens 20a, 20b, 20c, 20d are conspicuous.

  In the present embodiment, the above-described gain adjustment processing and gradation correction processing are performed in order to correct the luminance unevenness and color unevenness as described above.

  FIG. 4 is a graph showing the video signal level and the in-screen luminance with respect to the screen horizontal coordinates before the gain adjustment processing. FIG. 5 is a graph showing the video signal level and the in-screen luminance with respect to the horizontal coordinate of the screen after the gain adjustment processing. FIG. 6 is a graph showing the video signal level and the in-screen brightness with respect to the horizontal coordinate of the screen after the gradation correction process.

  4 to 6, the horizontal axis represents the screen horizontal coordinate, the left vertical axis represents the video signal level, and the right vertical axis represents the in-screen brightness [%]. The in-screen brightness represents the relative magnitude of the brightness in the screen 20 with the highest brightness in the screen 20 being 100%. 4 to 6, graphs representing video signal levels are indicated by reference signs “31” to “33”, and graphs representing in-screen luminance are indicated by reference signs “34” to “36”.

  As described above, the video signal output from the video source 5 shown in FIG. 1 is input to the video input circuit 4d and converted into a digital video signal. For example, when the luminance value of each pixel of a video represented by a digital video signal is represented by 8-bit gradations of 0, 255, R, G, and B, the whole represents a white pixel. The video signal is converted into a digital video signal having video signal levels of R = 255, G = 255, and B = 255. In addition, a video signal that represents a black pixel as a whole is converted into a digital video signal having a video signal level of R = 0, G = 0, and B = 0.

  The digital video signal is finally output as a video to the screen 2 via the video processing circuit 4a and the video display device 3a. Here, consider a case where the brightness of the peripheral portion S1 of the screen 20 is dark when a video is displayed on the screen 20 of the screen 2 based on a video signal representing a white pixel. In this case, even if the video signal level of the pixel corresponding to the peripheral portion S1 of the screen 20 is partially amplified to increase the luminance of the peripheral portion S1 of the screen 20 on the screen 2, the video signal level is already Since it is 255 which is the maximum value of the 8-bit gradation, it cannot be further increased.

  Therefore, in the present embodiment, in the video processing circuit 4a, the video signal level in the entire area of the screen 20 is once attenuated, and the attenuation is corrected for luminance unevenness and color unevenness of pixels corresponding to the peripheral portion S1 of the screen 20. Assign to the amplification.

  Specifically, as shown in the following formula (1), video signals Ri, Gi, Bi corresponding to R, G, B input to the video processing circuit 4a correspond to R, G, B. By multiplying gain adjustment coefficients Rgain, Ggain, and Bgain, respectively, the dynamic ranges of the video signals Ro, Go, and Bo output from the video processing circuit 4a are reduced.

  In the example shown in FIGS. 4 to 6, since the luminance unevenness between the central portion S0 and the peripheral portion S1 of the screen 20, that is, the difference in luminance is 10% at the maximum for all of R, G, and B, the gain adjustment coefficient is set to Rgain. = 0.9, Ggain = 0.9, and Bgain = 0.9. As a result, a digital video signal representing white pixels as a whole is converted into a digital video signal of R = 230, G = 230, and B = 230 according to the equation (1) in the video processing circuit 4a as shown in FIG. Is converted to The difference between the luminance value after the conversion and the luminance value before the conversion is the luminance value correction range CR.

  Within this correction range CR, the luminance value of the pixel corresponding to the peripheral portion S1 of the screen 20 can be amplified. That is, for each of R, G, and B, the luminance value of the pixel corresponding to the peripheral portion S1 of the screen 20 can be amplified to 10%.

  Therefore, in the video processing circuit 4a, only the pixels corresponding to the peripheral portion S1 of the screen 20 are amplified by gradation correction processing. Specifically, as shown in FIG. 6, the luminance value of the pixel corresponding to the end portion of the peripheral portion S1 of the screen 20 is amplified by 10%, and the pixel corresponding to the remaining portion of the peripheral portion S1 is displayed on the screen 20. The gain gradually decreases as the center portion S0 approaches, and is amplified so that the gain becomes zero (0) at the boundary with the central portion S0. For example, the luminance value of the pixel corresponding to the end of the peripheral portion S1 of the screen 20 is amplified by 255−230 = + 25 at the video signal level.

  Thus, by amplifying the luminance values of the pixels corresponding to the peripheral portion S1 of the screen 20, the luminance in the screen 20 can be made uniform for R, G, and B, respectively. Therefore, uneven brightness and uneven color within the screen 20 can be reduced.

  As described above, in order to correct luminance unevenness and color unevenness by the gain adjustment processing and gradation correction processing, the luminance of the central portion S0 and the peripheral portion S1 of the screen 20 is measured in advance, and information on luminance (hereinafter referred to as “luminance”). Information (sometimes referred to as “information”). In the present embodiment, at the stage of manufacturing the video display device 1, the luminance of the central portion S0 and the peripheral portion S1 of the screen 20 is measured by a camera or a luminance meter for each of R, G, and B that are the three primary colors of light. The luminance information is stored in the memory circuit 4c built in the video display device 1. The luminance information may be a luminance measurement value itself or a value obtained from the luminance measurement value.

  FIG. 7 is a diagram for explaining a method of measuring luminance data in the manufacturing stage of the video display device 1. At the manufacturing stage of the video display device 1, the luminance across the entire screen 20 of the screen 2 is measured by the luminance meter 7. The luminance meter 7 is connected to the external control device 6.

  First, in the video display device 1, video is displayed on the entire screen 20 based on a video signal representing white. At this time, while switching to monochromatic display of R, G, B, the luminance meter 7 causes the screen center R0, the screen upper end R1, the screen lower end R2, the screen left end R3, the screen right end R4, and the screen four corners R5 to R5. The luminance of a total of nine areas of R8 is measured. The measurement data of the luminance meter 7, that is, the luminance data indicating the luminance of each area measured is transmitted to the external control device 6 connected to the luminance meter 7.

  The screen upper end R1, the screen lower end R2, the screen left end R3, the screen right end R4, and the screen four corners R5 to R8 correspond to the periphery of the screen 20 and surround the screen center R0. The screen corners R5 to R8 include a screen upper left corner R5, a screen upper right corner R6, a screen lower left corner R7, and a screen lower right corner R8. Here, “upper”, “lower”, “right”, and “left” are when the screen 20 is viewed from a direction perpendicular to the screen 20.

  The external control device 6 uses the measurement data transmitted from the luminance meter 7 for the eight areas of the screen upper end R1, screen lower end R2, screen left end R3, screen right end R4, and screen four corners R5 to R6. A magnification, which is a ratio of the brightness of each area to the brightness of the screen center R0, is calculated. The external control device 6 calculates the magnification for each of R, G, and B, and data representing 8 areas × 3 colors = 24 magnifications (hereinafter sometimes referred to as “magnification data”) and 3 in the screen center R0. Color luminance data, that is, a total of 27 pieces of data including three pieces of luminance data is transmitted to the unit unit 9 of the video display device 1.

  The three pieces of luminance data in the screen central portion R0 correspond to central luminance information that is luminance information relating to the luminance of the central portion 20 of the screen 20. The magnification data obtained for the eight areas of the screen left end portion R3, the screen right end portion R4, and the screen four corner portions R5 to R6 that are the peripheral portion of the screen 20 corresponds to the peripheral luminance information that is the luminance information related to the peripheral portion luminance. To do.

  The unit portion 9 includes the projection unit 3 and the electric circuit unit 4 shown in FIG. Specifically, the external control device 6 transmits the magnification data and the luminance data to the microcomputer circuit 4b of the electric circuit unit 4 included in the unit unit 9.

  The external control device 6 includes brightness data Rct, Gct, Bct of the screen center R0, brightness data Rn (n is an integer of 1 to 8), Gm (m is an integer of 1 to 8) around the screen center R0. 1 to 8), Bl (l is an integer of 1 to 8), magnification data RXn (n is an integer of 1 to 8), GXm (m is an integer of 1 to 8) around the center R0 of the screen 1 to 8) and BXl (l is an integer of 1 to 8) are calculated according to the following equation (2).

  The variables n, m, and l in Expression (2) correspond to the subscripts 1 to 8 of the reference symbols R1 to R8 that indicate the respective areas around the screen center portion R0. The same applies to the following. When the variables n, m, and l are 1, the data of the screen upper end R1 is represented. When the variables n, m, and l are 2, the data of the screen lower end R1 is represented. When the variables n, m, and l are 3, the data of the screen left end R3 is represented. When the variables n, m, and l are 4, it represents the data at the right end R4 of the screen. When the variables n, m, and l are 5, the data at the upper left corner R5 of the screen is represented. When the variables n, m, and l are 6, data in the upper right corner R6 of the screen is represented. When the variables n, m, and l are 7, data in the lower left corner R7 of the screen is represented. When the variables n, m, and l are 8, the data at the lower right corner R8 of the screen is represented.

  The video display device 1 stores the magnification data and the luminance data transmitted from the external control device 6 and received by the microcomputer circuit 4b in the memory circuit 4c by the microcomputer circuit 4b. The magnification data and the luminance data stored in the memory circuit 4c are read out by the microcomputer circuit 4b and given to the video processing circuit 4a.

  As shown in FIG. 7, the video processing circuit 4a has a screen center portion R0, a screen upper end portion R1, a screen lower end portion R2, a screen left end portion R3, a screen right end portion R4, and screen corners R5 to R8. Is divided into a total of nine areas, and gradation correction processing is performed. The video processing circuit 4a includes eight gradation correction circuits respectively corresponding to the eight areas R1 to R8 other than the area of the screen center portion R0 shown in FIG. The video processing circuit 4a performs gradation correction processing for each area by each gradation correction circuit.

  Specifically, the video processing circuit 4a is configured to reduce the dynamic range of the entire video signal by the above formula (1), that is, the R, G, B video signal Ro after gain adjustment processing. , Go, Bo are multiplied by gradation correction coefficients Rgradn, Ggradm, Bgradl (n, m, l are integers of 1 to 8), which are parameters of gradation correction processing, as shown in the following equation (3). The gradation correction coefficients Rgradn, Ggradm, and Bgradl (n, m, and l are integers of 1 to 8) are variables n, m, and l (n, m, and l are integers of 1 to 8) for each color of R, G, and B. ) Is determined for each of the areas R1 to R8 corresponding to the

  In this way, the video processing circuit 4a applies the gradation correction coefficients Rgradn, Ggradm, Bgradl (n, m, B) to the R, G, B video signals Ro, Go, Bo after the gain adjustment processing as shown in Expression (3). l is an integer of 1 to 8) to correct luminance unevenness and color unevenness of the entire screen. In Expression (3), “Rgain × Rin” represents an R video signal after gain adjustment processing in the area indicated by the variable n, and “Ggain × Gim” represents after gain adjustment processing in the area indicated by the variable m. “Bgain × Bil” represents the B video signal after the gain adjustment processing in the area indicated by the variable l.

  FIG. 8 is a diagram schematically showing a multi-screen display device 10 in which four video display devices 1a, 1b, 1c, and 1d are combined. The multi-screen display device 10 is configured by combining four video display devices 1 shown in FIG. In FIG. 8, in order to distinguish the four video display devices 1, subscripts “a”, “b”, “c”, and “d” are added to the reference numeral “1” of the video display device, 1 video display device 1a ”,“ second video display device 1b ”,“ third video display device 1c ”, and“ fourth video display device 1d ”. When it is not necessary to distinguish the four video display apparatuses 1, the subscripts “a” to “d” of the reference sign “1” of the video display apparatus are omitted.

  In FIG. 8, for easy understanding, the projection unit 3 and the electric circuit unit 4 of each of the video display devices 1 a, 1 b, 1 c, and 1 d are omitted, and only the screen 20 of the screen 2 is shown. In FIG. 8, the screen 20 of the screen 2 of each video display device 1 is given the subscripts “a”, “b”, “c”, “d” indicating the video display device 1, and the first screen 20a. , A second screen 20b, a third screen 20c, and a fourth screen 20d. The multi-screen 21 that is the display screen of the multi-screen display device 10 is configured by combining the first to fourth screens 20a to 20d as shown in FIG.

  In the multi-screen display device 10, the video display devices 1 a to 1 d are connected by a communication cable 8 in order to perform communication between the video display devices 1 a to 1 d. In the example shown in FIG. 8, the first video display device 1a and the second video display device 1b are connected, the second video display device 1b and the third video display device 1d are connected, and the third video display device 1d is connected. The fourth video display device 1c is connected. Thus, the some video display apparatuses 1a-1d which comprise the multiscreen display apparatus 10 are connected so that communication is possible.

  A unique ID number is assigned to each of the video display devices 1a to 1d. The four video display devices 1a to 1d are controlled by a master device (hereinafter sometimes simply referred to as “master”) that controls all of the controls when communicating between the video display devices 1a to 1d. Assigned to the slave.

  Whether each of the video display devices 1a to 1d is used as a master or a slave is set by a user, for example. The user can set each of the video display devices 1a to 1d as a master or a slave by operating an operation unit (not shown) of the external control device 6 shown in FIG. As described above, each of the video display devices 1a to 1d is determined in advance as a master or a slave.

  Based on the operation result of the operation unit by the user, the external control device 6 instructs the microcomputer circuit 4b of the electric circuit unit 4 of each of the video display devices 1a to 1d to operate as a master (hereinafter referred to as “master instruction”). A control signal (hereinafter referred to as a “slave instruction signal”) that instructs to operate as a slave. The video display device 1 that has received the master instruction signal starts an operation as a master. The video display device 1 that has received the slave instruction signal starts operation as a slave.

  In the example shown in FIG. 8, the ID numbers of the video display devices 1a to 1d are ID1, ID2, ID3, and ID4, respectively. The first video display device 1a is a master, and the other three video display devices, that is, the second to third video display devices 1b, 1c, and 1d are a first slave, a second slave, and a third slave, respectively. Therefore, in the example shown in FIG. 8, the first video display device 1a that is the master controls the second to fourth video display devices 1b, 1c, and 1d that are the first to third slaves.

  As described above, a plurality of video display devices 1 are connected by the communication cable 8 and each video display device 1a to 1d is set as a master or a slave, whereby the installation of the multi-screen display device 10 is completed. Thereafter, luminance unevenness and color unevenness in the screen 20 of each video display device 1 and luminance unevenness and color unevenness between the screens 20a to 20d constituting the multi-screen 21 are corrected.

  FIG. 9 is a flowchart showing a processing procedure of luminance unevenness and color unevenness correction processing in the video display device 1 (hereinafter sometimes referred to as “master video display device” or simply “master”) 1 set as the master. Each process of the flowchart shown in FIG. 9 is executed by the master video display device 1. In the example shown in FIG. 8, it is executed by the first video display device 1a as the master. The processing of the flowchart shown in FIG. 9 is set to the master when the video display device 1 set as the master is turned on or the video display device 1 receives a master instruction signal from the external control device 6. And the process proceeds to step a1.

  In step a1, the master video display device 1 transmits a correction start command to all slaves. In the example illustrated in FIG. 8, the first video display device 1 a that is a master transmits a correction start command to the second to fourth video display devices 1 b to 1 d that are first to third slaves.

  The master video display device 1 uses the microcomputer circuit 4b via the communication cable 8 to send a correction start command to a video display device set as a slave (hereinafter referred to as “slave video display device” or simply “slave”). Yes) to each one. The correction start command is given to a slave that is not directly connected to the master via the communication cable 8 via a slave that is directly connected to the master via the communication cable 8.

  For example, as shown in FIG. 8, when the master 1a and the first slave 1b are connected, the first slave 1b and the third slave 1d are connected, and the third slave 1d and the second slave 1c are connected. The third slave 1d is given a correction start command via the first slave 1b. A correction start command is given to the second slave 1c via the first slave 1b and the third slave 1d. When the correction start command is transmitted in this way, the master video display device 1 proceeds to step a2.

  In step a <b> 2, the master video display device 1 performs a gain adjustment process that attenuates the luminance of the entire area of the screen 20. Specifically, the master video display device 1 reads the magnification data RXn, GXm, BXl stored in the memory circuit 4c in the device itself. The magnification data RXn, GXm, and BXl is obtained and stored for each area indicated by the variables n, m, and l for each color of R, G, and B.

  The master obtains the minimum value min (RXn), min (GXm), min (BXl) from the read magnification data RXn, GXm, BXl of each area for each color of R, G, B, and this is the minimum The magnification data is determined as RXmin, GXmin, BXmin.

  Next, as shown in the following equation (4), the master substitutes the minimum magnification data RXmin, GXmin, BXmin as the gain adjustment coefficients Rgain, Ggain, Bgain into the equation (1), and the entire area of the screen 20 Are prepared for correcting the luminance and color of the peripheral portion S1 of the screen 20. When the gain adjustment process is performed in this way, the master proceeds to step a3. In Expression (4), variables n, m, and l are integers of 1 to 8.

  In step a3, the master video display device 1 performs gradation correction processing for correcting the luminance and color of the peripheral portion S1 of the screen 20 by the gradation correction circuit in the video processing circuit 4a. As described above, the gradation correction circuit is provided for each area of the peripheral portion S1 of the screen 20, and performs gradation correction processing independently. In the example shown in FIG. 7, the screen upper end R1, the screen lower end R2, the screen left end R3, the screen right end R4, and the screen four corners R5 to R8, which are peripheral portions S1 of the screen 20, are independently provided. A gradation correction process is performed by a gradation correction circuit provided.

  In the gradation correction process, actually, as shown in the following equation (5), the reciprocal of the magnification data RXn, GXm, BXl stored in the memory circuit 4c is used as the gradation correction coefficients Rgradn, Ggradm, Bgradl. Substituting into (3), the brightness and color of the peripheral portion S1 of the screen 20 are corrected. When the gradation correction processing for correcting the luminance and color of the peripheral portion S1 of the screen 20 is performed in this way, the master proceeds to step a4.

  In this way, the video processing circuit 4a calculates the luminance value included in the video signal so that the luminance unevenness in the screen 20 is corrected based on the magnification data that is the peripheral luminance information stored in the memory circuit 4c. to correct. As described above, the magnification data stored in the memory circuit 4c includes the luminance data of the screen central portion S0 as the central luminance information, the screen upper end portion R1, which is the peripheral portion S1 of the screen 20, the screen lower end portion R2, and the screen. It is obtained using the luminance data of each area of the left end R3, the screen right end R4 and the screen corners R5 to R8. Therefore, correcting the luminance value based on the magnification data corresponds to correcting the luminance value based on the central luminance information and the peripheral luminance information.

  In step a4, the master video display device 1 measures the light amount of the light source 3c by the luminance sensor 3e in order to correct the luminance unevenness and color unevenness due to the change in the light amount of the light source 3c, and the measurement result. Is acquired as brightness sensor data (hereinafter referred to as “initial brightness sensor data”) SensI representing the initial light amount of the light source 3c. When the initial luminance sensor data SensI is acquired, the master proceeds to step a5.

  In step a5, the master is the luminance value of the central portion S0 of the screen 20 after correcting the luminance and color of the peripheral portion S1 of the screen 20 in step a3 according to the following formula (6), that is, the corrected luminance value. Luminance data Rbrt, Gbrt, Bbrt are calculated. In Expression (6), SensN is the latest luminance sensor data described later, and SensI is substituted when SensN is not acquired. When the luminance data Rbrt, Gbrt, Bbrt of the central portion S0 of the screen 20 after the correction in step a3 is calculated, the master proceeds to step a6.

  In step a6, the master transmits a transmission command instructing all the slaves to transmit the luminance data Rbrt, Gbrt, Bbrt as the corrected luminance values of the central portion S0 of the screen 20, that is, the corrected luminance values. To do. The transmission command is given to each slave in the same manner as the correction start command described above. When transmitting the transmission command, the master proceeds to step a7.

  In step a7, the master determines whether or not the luminance data Rbrt, Gbrt, Bbrt of the center portion S0 of the screen 20 after correction has been received from all the slaves. If it is determined in step a7 that the luminance data Rbrt, Gbrt, Bbrt of the center portion S0 of the corrected screen 20 has been received from all slaves, the process proceeds to step a8, and the corrected screen is displayed from all slaves. If it is determined that the luminance data Rbrt, Gbrt, Bbrt of the 20 central portion S0 has not been received, it waits until it is received from all the slaves.

  In step a8, as shown in the following formula (7), the master displays the screen 20 after correction of all the video display devices 1 including the master and all the slaves, that is, the first to fourth video display devices 1a to 1d. The minimum value min (Rbrti), min (Gbrti), min (Bbrti) is obtained from the luminance data Rbrti, Gbrti, Bbrti (i is an integer of 1 to 4) of the central portion S0, and the central portion S0 of the screen 20 is obtained. Target luminance data Rtgt, Gtgt, and Btgt are determined. The variable i in Formula (7) is an integer of 1-4. The target luminance data corresponds to a target luminance value that is a target for the entire multi-screen 21.

  Next, in step a9, the master transmits the target luminance data Rtgt, Gtgt, Btgt determined in step a8 to all the slaves. Next, in step a10, the master corrects the luminance value of the central portion S0 of the screen 20 for each color based on the target luminance data Rtgt, Gtgt, Btgt of the central portion S0 of the screen 20 determined in step a8. Correct brightness and color. Specifically, the video processing circuit 4a sets the gain adjustment coefficients Rgain, Ggain, and Bgain in the above equation (3) of the video signal to the center of the screen 20 determined in step a8 as shown in the following equation (8). By correcting with the target luminance data Rtgt, Gtgt, Btgt of the portion S0, the luminance and color of the central portion S0 of the screen 20 are corrected.

  As will be described later, the gain adjustment coefficients Rgain, Ggain, and Bgain are similarly corrected in each slave. As a result, the luminance and color of the central portion S0 of each screen 20 constituting the multi-screen 21 are corrected, so that the luminance unevenness and color unevenness of the central portion S0 between the screens 20a to 20d can be corrected. When the luminance unevenness and the color unevenness in the central portion S0 in the screen 20 and between the screens 20a to 20d are corrected in this way, the master moves to step a11.

  In step a11, the master measures the light quantity of the light source 3c with the brightness sensor 3e, and acquires the measurement result as brightness sensor data (hereinafter referred to as “latest brightness sensor data”) SensN representing the latest light quantity of the light source 3c.

  After obtaining the latest luminance sensor data SensN, the process returns to step a5, and the processes in steps a5 to a11 are repeated. Thereby, in step a11, the light quantity of the light source 3c is periodically measured by the luminance sensor 3e, and in steps a5 to a10, the luminance data Rbrt, Gbrt, Bbrt of the central portion S0 of the screen 20 is corrected, and a new gain is obtained. Adjustment coefficients Rgain, Ggain, and Bgain are calculated. By repeating these processes, it is possible to correct luminance unevenness and color unevenness due to a change in the light amount of the light source 3c and the like.

  FIG. 10 is a flowchart showing a processing procedure of luminance unevenness and color unevenness correction processing in the slave video display device 1. Each process of the flowchart shown in FIG. 10 is executed by the slave video display device 1. When there are a plurality of slaves, it is executed by each slave. In the example shown in FIG. 8 described above, this is executed by the second to fourth video display devices 1b, 1c and 1d which are the first to third slaves, respectively. The processing of the flowchart shown in FIG. 10 is set to the slave when the video display device 1 set as the slave is turned on or the video display device 1 receives the slave instruction signal from the external control device 6. And the process proceeds to step b1.

  In step b1, the slave video display device 1 determines whether or not a correction start command transmitted from the master has been received. This correction start command is transmitted by the master to each slave in step a1 shown in FIG. If it is determined in step b1 that the correction start command has been received, the slave proceeds to step b2, and if it is determined that the correction start command has not been received, the slave waits until it is received.

  In step b2, the slave video display device 1 performs a gain adjustment process for attenuating the luminance of the entire area of the screen 20, similarly to step a2 shown in FIG. Specifically, the slave video display device 1 reads the magnification data RXn, GXm, and BXl stored in the memory circuit 4c of the device itself, and the minimum value min of the magnification data for each of the R, G, and B colors. (RXn), min (GXm), and min (BXl) are obtained and determined as minimum magnification data RXmin, GXmin, and BXmin.

  Next, as shown in the equation (4), the slave substitutes the minimum magnification data RXmin, GXmin, BXmin into the equation (1) as gain adjustment coefficients Rgain, Ggain, Bgain, and The video signal level is attenuated, and preparations for correcting the luminance and color of the peripheral portion S1 of the screen 20 are made. When the gain adjustment process is performed in this manner, the slave proceeds to step b3.

  In step b3, the slave video display device 1 uses the gradation correction circuit in the video processing circuit 4a to correct the luminance and color of the peripheral portion S1 of the screen 20 in the same manner as in step a3 shown in FIG. Perform correction processing. In the example shown in FIG. 7, the screen upper end R1, the screen lower end R2, the screen left end R3, the screen right end R4, and the screen four corners R5 to R8, which are peripheral portions S1 of the screen 20, are independently provided. A gradation correction process is performed by a gradation correction circuit provided.

  In the gradation correction process, actually, as shown in the equation (5), the reciprocal of the magnification data RXn, GXm, BXl stored in the memory circuit 4c is used as the gradation correction coefficients Rgradn, Ggradm, Bgradl. Substituting into (3), the brightness and color of the peripheral portion S1 of the screen 20 are corrected. When gradation correction processing for correcting the luminance and color of the peripheral portion S1 of the screen 20 is performed in this manner, the slave proceeds to step b4.

  In step b4, the slave video display device 1 uses the light source in the same manner as in step a4 shown in FIG. 9 in order to correct luminance unevenness and color unevenness over time caused by changes in the light amount of the light source 3c. The amount of light 3c is measured by the luminance sensor 3e, and the measurement result is acquired as initial luminance sensor data SensI. When the initial luminance sensor data SensI is acquired, the slave proceeds to step b5.

  In step b5, in the same manner as in step a5 shown in FIG. 9 described above, the slave performs the central portion of the screen 20 after correcting the luminance and color of the peripheral portion S1 of the screen 20 in step b3 according to the above equation (6). The brightness data Rbrt, Gbrt, Bbrt, which are the brightness values of S0, that is, the corrected brightness values, are calculated. When the latest brightness sensor data SensN in the equation (6) is not acquired, SensI is substituted. When the luminance data Rbrt, Gbrt, Bbrt of the central portion S0 of the screen 20 after the correction in step b3 is calculated, the slave proceeds to step b6.

  In step b6, the slave determines whether or not it has received a transmission command for luminance data Rbrt, Gbrt, Bbrt of the center portion S0 of the corrected screen 20 transmitted from the master. This transmission command is transmitted to each slave by the master in step a6 shown in FIG. If the slave determines in step b6 that it has received a transmission command for the luminance data Rbrt, Gbrt, Bbrt of the central portion S0 of the screen 20 after correction, the slave proceeds to step b7, where the central portion of the screen 20 after correction is performed. If it is determined that the transmission command for the luminance data Rbrt, Gbrt, Bbrt of S0 has not been received, the process waits until it is received.

  In step b7, the slave transmits the luminance data Rbrt, Gbrt, Bbrt of the corrected center portion S0 of the screen 20 acquired in step b5 to the master. When the luminance data Rbrt, Gbrt, Bbrt of the central portion S0 of the screen 20 after correction is transmitted to the master, the slave proceeds to step b8.

  In step b8, the slave determines whether or not the target luminance data Rtgt, Gtgt, Btgt of the central portion S0 of the screen 20 transmitted from the master has been received. This target brightness data is transmitted to each slave by the master in step a9 shown in FIG. If it is determined in step b8 that the target luminance data has been received, the slave proceeds to step b9. If the slave determines that the target luminance data has not been received, the slave waits until it is received.

  In step b9, in the same way as in step a10 shown in FIG. 9, the slave determines the luminance value of the central portion S0 of the screen 20 based on the received target luminance data Rtgt, Gtgt, Btgt of the central portion S0 of the screen 20. Is corrected for each color to correct luminance and color. Specifically, in each slave, the video processing circuit 4a receives the gain adjustment coefficients Rgain, Ggain, and Bgain in the equation (3) of the video signal as shown in the equation (8) by the central portion of the screen 20 of the video signal. Correction is performed with the target luminance data Rtgt, Gtgt, Btgt of S0, and the luminance and color of the central portion S0 of the screen 20 are corrected.

  Next, in step b10, the slave measures the light quantity of the light source 3c by the luminance sensor 3e in the same manner as in step a11 shown in FIG. 9, and acquires the measurement result as the latest luminance sensor data SensN.

  After acquisition of the latest brightness sensor data SensN, the process returns to step b5, and the processes in steps b5 to b10 described above are repeated. Thereby, in step b10, the light quantity of the light source 3c is periodically measured by the luminance sensor 3e, and in steps b5 to b9, the luminance data Rbrt, Gbrt, Bbrt of the central portion S0 of the screen 20 is corrected, and new gain adjustment is performed. The coefficients Rgain, Ggain, and Bgain are calculated. By repeating these processes, it is possible to correct luminance unevenness and color unevenness due to a change in the light amount of the light source 3c and the like.

  As described above, in the present embodiment, the central luminance information regarding the luminance of the central portion S0 of the screen 20 of each video display device 1 and the peripheral luminance information regarding the luminance of the peripheral portion S1 surrounding the central portion S0 are stored in the memory circuit 4c. Remember. Specifically, at the stage of manufacturing each video display device 1, the luminance of the central portion S0 and the peripheral portion S1 of the screen 20 of the video display device 1 is measured, the luminance data of the central portion S0, and the central portion S0. Magnification data that is the ratio of the luminance of the peripheral portion S1 to the luminance is stored in the memory circuit 4c. The luminance data of the central portion S0 corresponds to central luminance information. The magnification data corresponds to peripheral luminance information.

  When the multi-screen display device 10 is installed by combining a plurality of video display devices 1, that is, when the multi-screen 20 is configured by combining the screens 20 of the plurality of video display devices 1, Gain adjustment processing and gradation correction processing are performed so as to eliminate luminance unevenness and color unevenness in the screen 20, and the luminance value included in the video signal is corrected.

  Thereafter, the brightness values of the respective video display devices 1 corrected by the gain adjustment process and the gradation correction process are communicated, the target brightness value of the entire multi-screen 20 is obtained based on these brightness values, and based on the target brightness value, Each image display device 1 corrects the luminance value.

  Thus, the multi-screen display device 10 that can easily and accurately correct the luminance unevenness in each screen 20 in the multi-screen 21 and the luminance unevenness between the plurality of screens 20 constituting the multi-screen 21 is provided. be able to.

  In the present embodiment, since the luminance value is corrected for each color, color unevenness can also be corrected. That is, in the present embodiment, the color unevenness in each screen 20 in the multi-screen 21 and the color unevenness between the plurality of screens 20 constituting the multi-screen 21 can be corrected easily and accurately. Therefore, the multi-screen display device 10 that can easily and accurately correct luminance unevenness and color unevenness in each screen 20 in the multi-screen 21 and luminance unevenness between the plurality of screens 20 constituting the multi-screen 21. Can be provided.

  Further, in the present embodiment, when the multi-screen display device 10 is assembled, an adjustment without luminance unevenness and color unevenness is easily performed between the plurality of screens 20 constituting the multi-screen 21 without using a camera and a luminance meter. It is possible.

  In the present embodiment, each video display device 1 includes a luminance sensor 3e as a measurement unit that measures the amount of light emitted from the light source 3c that illuminates the screen 20. Then, the video processing circuit 4a corrects the luminance value based on the measurement result of the luminance sensor 3e in Step a5 to Step a11 of FIG. 9 and Step b5 to Step b10 of FIG. In other words, in the present embodiment, the brightness of each video display device 1 is changed over time during operation because the brightness of each video display device 1 constituting the multi-screen display device 10 is communicated and corrected in real time. The luminance between the plurality of screens 20 constituting the multi-screen 21 can always be kept uniform even if the brightness decreases.

  In the present embodiment described above, the case where one screen 20 is divided into nine areas in FIG. 7 and gradation correction processing is performed on eight areas around the screen 20 has been described. It is not always necessary to have nine areas to divide, and it is not always necessary to have eight areas for performing gradation correction processing. For example, gradation correction processing may be performed in only four areas on the top, bottom, left, and right of the screen 20 or in nine or more areas. As described above, even when gradation correction processing is performed in only four areas on the top, bottom, left, and right of the screen 20 or in nine or more areas, the same effects as in the present embodiment can be obtained.

<Second Embodiment>
In each video display device 1 constituting the multi-screen display device 10 in the first embodiment described above, a peripheral portion of the screen 20 with respect to the central portion S0 of the screen 20 in the screen 20 as the light amount of the light source 3c changes with time. In some cases, the attenuation amount of the luminance of S1 is reduced. In this case, the gradation correction coefficient adjusted at the time of installation of the multi-screen display device 10 is not an appropriate value. May be. Therefore, in this embodiment, the gradation correction coefficient is reset.

  FIG. 11 is a graph showing the video signal level and the in-screen luminance with respect to the screen horizontal coordinates after the gradation correction process when the light amount of the light source 3c does not change with time. FIG. 12 is a graph showing the video signal level and the in-screen luminance with respect to the screen horizontal coordinates after the gradation correction processing when the light amount of the light source 3c changes with time. FIG. 11 corresponds to a graph representing the video signal level and the luminance within the screen with respect to the horizontal coordinate of the screen after gradation correction processing when the multi-screen display device 10 is installed.

  11 and 12, the horizontal axis represents the screen horizontal coordinate, the left vertical axis represents the video signal level, and the right vertical axis represents the in-screen brightness [%]. The in-screen brightness represents the relative magnitude of the brightness in the screen 20 with the highest brightness in the screen 20 being 100%. In FIGS. 11 and 12, the in-screen brightness of the screen center portion S0 when the light amount of the light source 3c in FIG. 11 does not change with time is shown as 100%. In FIGS. 11 and 12, graphs representing video signal levels are indicated by reference numerals “41” and “42”, and graphs representing in-screen luminance are indicated by reference numerals “43” and “44”.

  When the multi-screen display device 10 shown in FIG. 11 is installed, the luminance attenuation amount LA1 of the peripheral portion S1 with respect to the central portion S0 of the screen 20 changes with time, specifically, the light amount of the light source 3c decreases. Reduce. Then, as shown in FIG. 12, when the in-screen luminance of the central portion S0 of the screen 20 becomes 75% of the value at the time of installing the multi-screen display device 10, the luminance attenuation amount LA2 of the peripheral portion S1 is It becomes smaller than the value LA1 when the multi-screen display device 10 is installed (LA1> LA2).

  Therefore, it is appropriate to reduce the gradation correction amount. In this embodiment, the gradation correction coefficient GC representing the gradation correction amount is reset in order to reduce the gradation correction amount. For example, when the light amount of the light source 3c decreases as shown in FIG. 12, the gradation correction coefficient GC2 is made smaller than the gradation correction coefficient GC1 set when the multi-screen display device 10 shown in FIG. 11 is installed (GC2 <GC1). That is, in the present embodiment, the video processing circuit 4a corrects the luminance value based on the change amount of the measurement result of the luminance sensor 3e. Specifically, the gradation correction coefficient is reset as follows.

  When correcting luminance unevenness and color unevenness due to a change in the light amount of the light source 3c and the like, the gain adjustment coefficients Rgain, Ggain, Bgain obtained by the equation (8) and the equation (2) are obtained. Substituting the magnification data RXn (n is an integer from 1 to 8), GXm (m is an integer from 1 to 8), and BX1 (l is an integer from 1 to 8) into the following equation (9), the gradation correction coefficient Rgradn , Ggradm, Bgradl are recalculated and reset. By resetting the value obtained by recalculation in this way as the gradation correction coefficient, gradation correction processing can be performed using a more appropriate gradation correction coefficient.

  As described above, in the present embodiment, the video processing circuit 4a corrects the luminance value based on the change amount of the measurement result of the luminance sensor 3e. Specifically, when a plurality of video display devices 1 constituting the multi-screen display device 10 communicate their brightnesses and perform correction in real time, an appropriate gradation correction coefficient is reset. Thereby, even when the luminance of each video display device 1 changes with time during operation, the luminance unevenness and color unevenness of the screen 20 of each video display device 1 can be corrected appropriately. Therefore, uneven luminance and uneven color at the edge of the screen 20 can be suppressed between the plurality of video display devices 1 adjacent to each other in the multi-screen display device 10.

<Third Embodiment>
In the first embodiment described above, the minimum magnification data RXmin, GXmin, BXmin is substituted into the equation (1) as the gain adjustment coefficients Rgain, Ggain, Bgain of the video signal of the video processing circuit 4a, and the screen 20 Preparation for correcting the luminance and color of the peripheral portion S1 of the screen 20 is performed by attenuating the video signal level of the entire area. However, if a limit value is not set for the amount of attenuation, the video level of the entire area of the screen 20 is greatly attenuated when extremely small magnification data exists, and the luminance performance of the central portion S0 of the screen 20 is deteriorated. It will be.

  Therefore, in the present embodiment, a limit value Xlimit is set for the attenuation amount, and when the minimum magnification data RXmin, GXmin, BXmin is lower than the limit value Xlimit, the limit value Xlimit is used as the minimum magnification data.

  Specifically, in step a2 in FIG. 9 and step b2 in FIG. 10, all the video display devices 1 that are the master and the slave each have minimum magnification data RXmin as shown in the following equation (10). , GXmin, BXmin, the larger one of the minimum value of the magnification data RXn, GXm, BXl (n, m, l are integers of 1 to 8) stored in the memory circuit 4c and the predetermined limit value Xlimit The value of is selected and calculated. Each video display device 1 uses the calculated values as gain adjustment coefficients Rgain, Ggain, and Bgain.

  Next, in step a3 in FIG. 9 and step b3 in FIG. 10, the master and all the slaves are the screen upper end R1, the screen lower end R2, the screen left end R3, and the screen right end R4 in the video processing circuit 4a. The gradation correction processing is performed by an independent gradation correction circuit for each of the screen corners R5 to R8.

  In the present embodiment, when the minimum magnification data RXn, GXm, BXl is smaller than the limit value Xlimit, the limit value Xlimit is selected as a gradation correction parameter. Specifically, the brightness and color of the peripheral portion S1 of the screen 20 are corrected by substituting the values shown in the following expression (11) into the gradation adjustment coefficients Rgradn, Ggradm, Bgradl in the expression (3). In Expression (11), variables n, m, and l are integers of 1 to 8.

  As described above, the video processing circuit 4a according to the present embodiment outputs the limit value as the corrected luminance value when the corrected luminance value is equal to or less than a predetermined limit value as shown in the equation (11). To do. Specifically, when the gradation correction processing is performed in each video display device 1, the gradation is changed when the difference between the luminance of the central portion S0 and the luminance of the peripheral portion S1 of the screen 20 is equal to or greater than a predetermined threshold value. An upper limit for correction is set. Thereby, luminance unevenness and color unevenness in the screen 20 of each video display device 1 can be reduced. Further, it is possible to minimize a decrease in luminance of the entire multi-screen 21 due to gradation correction processing.

  In the present embodiment, a case has been described in which a common limit value Xlimit is provided for R, G, and B. However, different limit values may be set for R, G, and B, respectively.

<Fourth embodiment>
In the present embodiment, in the video display device 1 that constitutes the multi-screen display device 10, when the luminance decreases by a predetermined threshold or more than the initial luminance value due to a change in the light amount of the light source 3 c over time, the video is displayed. Control is performed to stop the operation of the gradation correction circuit in the processing circuit 4a.

  Specifically, the luminance value at the time of manufacture stored in the memory circuit 4c is used as the initial luminance value. Then, the initial luminance value (hereinafter sometimes referred to as “initial luminance value”) is compared with the luminance value measured by the luminance sensor 3e (hereinafter also referred to as “measured luminance value”), and the initial luminance value is compared. When the measured luminance value is lower than the predetermined threshold value, in other words, when the ratio of the measured luminance value to the initial luminance value is equal to or lower than the predetermined luminance threshold value YDth, gradation correction in the video processing circuit 4a is performed. Stop circuit operation.

  For example, when the measured luminance value is reduced by 40% or more with respect to the initial luminance value, in other words, when the ratio of the measured luminance value to the initial luminance value is equal to or less than the luminance threshold YDth = 0.6, the gradation correction circuit Stop the operation.

  In this case, the luminance data Rbrt, Gbrt, Bbrt of the central portion S0 of the screen 20 after correcting the luminance and color of the peripheral portion S1 of the screen 20 obtained by the equation (6) is the minimum in the equation (6). The magnification data RXmin, GXmin, BXmin is set to “1” and is obtained according to the following equation (12). Using the luminance data Rbrt, Gbrt, Bbrt of the central portion S0 of the luminance data screen 20 obtained in this way, again in step a8 of FIG. Recalculate the target brightness.

  As described above, in the present embodiment, the video processing circuit 4a is configured to stop the gradation correction processing when the decrease in the brightness within the screen 20 of each video display device 1 is equal to or greater than a predetermined threshold. Control. That is, the video processing circuit 4a stops correcting the luminance value when the target luminance value of the entire multi-screen 20 is equal to or less than a predetermined threshold value.

  Thereby, when the brightness of the entire multi-screen 21 is lowered due to the change over time, it is possible to prevent the brightness from being lowered by performing the gradation correction process. Therefore, although there is a risk of uneven brightness and uneven color within the video display device 1, the brightness of the entire multi-screen 21 can be increased.

  DESCRIPTION OF SYMBOLS 1 Projection type video display apparatus, 1a 1st video display apparatus, 1b 2nd video display apparatus, 1c 3rd video display apparatus, 1d 4th video display apparatus, 2 screen, 2a 1st screen, 2b 2nd screen, 2c 2nd 3 screen, 2d 4th screen, 3 projection unit, 3a video display device, 3b condenser lens, 3c light source, 3d projection lens, 3e luminance sensor, 4 electrical circuit unit, 4a video processing circuit, 4b microcomputer circuit, 4c memory circuit 4d video input circuit, 5 video source, 6 external control device, 7 luminance meter, 8 communication cable, 9 unit section, 10 multi-screen display device, 20 screen, 20a first screen, 20b second screen, 20c third screen 20d 4th screen, 21 multi-screen.

Claims (6)

A multi-screen display device comprising a plurality of video display devices and displaying video based on a video signal on a multi-screen configured by combining the screens of the plurality of video display devices,
The plurality of video display devices are communicably connected,
Each video display device
Storage means for storing central luminance information relating to the luminance of the central portion of the screen of the video display device, and peripheral luminance information relating to the luminance of the peripheral portion surrounding the central portion;
Based on the central luminance information and the peripheral luminance information stored in the storage means, correction means for correcting the luminance value included in the video signal so that luminance unevenness in the screen of the video display device is corrected. And
Among the plurality of video display devices, the correction unit of the video display device that is predetermined as a master device for controlling the other video display device is: (a) the luminance corrected by the correction unit of the other video display device (B) a target luminance that is a target of the entire multi-screen based on the acquired luminance value and the luminance value corrected by the correcting means of the video display device that is predetermined as the master device And (c) transmitting the obtained target luminance value to the other video display device and, based on the obtained target luminance value, the correction means of the video display device that is predetermined as the master device. Correct the corrected brightness value,
When the correction unit of the other video display device receives the target luminance value from the correction unit of the video display device predetermined as the master device, the correction unit of the video display device is based on the received target luminance value. A multi-screen display device that corrects the luminance value corrected by the correcting means. Each video display device includes a measuring unit that measures the amount of light emitted from a light source that illuminates the screen,
The multi-screen display device according to claim 1, wherein the correction unit of each video display device corrects the luminance value based on a measurement result of the measurement unit.   The multi-screen display device according to claim 2, wherein the correction unit of each video display device corrects the luminance value based on a change amount of a measurement result of the measurement unit.   The correction means of each video display device outputs the limit value as the corrected luminance value when the corrected luminance value is equal to or less than a predetermined limit value. The multi-screen display device according to any one of the above.   The correction means of each video display device stops the correction of the luminance value when the target luminance value of the entire multi-screen becomes a predetermined threshold value or less. The multi-screen display device described.   The multi-screen display device according to claim 1, wherein the correction unit of each video display device corrects the luminance value for each color.

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