JP2011048100A - Emission intensity measurement method, emission intensity measurement device and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an emission intensity measurement method, an emission intensity measurement device and a computer program capable of precisely estimating an emission intensity from a display surface of a display panel even when either the display panel or a backlight is changed by aging. <P>SOLUTION: A personal computer (PC) emits backlight with a predetermined emission intensity, successively detects emission intensity of the peripheral part of the display surface 2 and emission intensity of the central part of the display surface 2 when being set on each gradation level and stores correlation information which allows the detected values to correlate to one another onto a correlation table beforehand. The PC produces the correlation information in accordance with the light amount of the backlight upon calibration from the correlation information which is stored beforehand on the correlation table when calibrating a gradation characteristic of a liquid crystal panel. Therein, the PC detects the emission intensity of the peripheral part of the display surface 2 with a swing sensor 30 and calculates the emission intensity on the center part of the display surface 2 based on the detected emission intensity of the peripheral part and the produced correlation information. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light emission intensity measurement method for measuring light emission intensity from a display surface of a display device that displays an image on a display panel, a light emission intensity measurement device, and a computer program for realizing the light emission intensity measurement method by a computer.

  The liquid crystal display device includes a liquid crystal panel in which a liquid crystal material is sealed between a pair of glass substrates, and a backlight disposed on the back of the liquid crystal panel, and an external personal computer (hereinafter referred to as a PC) connected to the liquid crystal display device. The video signal is input from. The gate driver and source driver incorporated in the liquid crystal display device are connected to the gate and source of the TFT that drives each pixel of the liquid crystal panel, and turn on / off the TFT based on the video signal input to the liquid crystal display device. In addition to being controlled, a voltage (input level to the liquid crystal panel) corresponding to the video signal is applied to the TFT that is turned on to change the light transmittance determined by the electro-optical characteristics of the liquid crystal substance. As a result, the liquid crystal display device displays an image in gradation by controlling the amount of light transmitted through the liquid crystal panel for each pixel.

  Since the electro-optical characteristics of the liquid crystal material are determined by the facing distance between the glass substrates in which the liquid crystal material is sealed, that is, the liquid crystal gap (thickness of the liquid crystal material), the liquid crystal gap determines the light transmittance of the liquid crystal display device. It is an important parameter. In a liquid crystal display device, due to manufacturing variations and the like, a pixel with a narrow liquid crystal gap and a widened pixel are mixed with respect to the design value of the liquid crystal gap. In some cases, gradation characteristics cannot be obtained. Further, the light emission intensity is adjusted by applying a voltage to the liquid crystal and generating a twist, but the light other than the front changes due to the twist, which causes a so-called viewing angle characteristic to deteriorate. The light other than the front side is adversely affected by an inexpensive measuring instrument having a wide measuring angle, particularly in contact with the panel, and accurate measurement cannot be expected.

  Therefore, as a method of obtaining a desired gradation characteristic, a look in which a gradation level (gradation value) expressed by an input video signal and an input level to a liquid crystal panel corresponding to the gradation level are associated with each other is used.・ Up-table (hereinafter referred to as LUT) is stored in memory, and gradation levels are converted into input levels based on the LUT, thereby correcting the gradation characteristics specific to each liquid crystal display device, and desired gradation characteristics. There is something that realizes.

  However, characteristics of the liquid crystal panel, the backlight, and the like change with the use of the liquid crystal display device. For this reason, when aging has occurred, the desired gradation characteristics cannot be realized even if the gradation characteristics are corrected based on the LUT stored at the time of manufacture or shipment of the liquid crystal display device. There is a fear. Also, the color temperature, brightness, and gradation characteristics of the screen required by the user may differ depending on the application used. These problems can be dealt with by performing a so-called calibration in which the LUT is updated on the user side after the liquid crystal display device is shipped.

  Calibration is a table in which the ideal brightness when the liquid crystal panel displays for each gradation level of the video is pre-associated, and the brightness when the liquid crystal panel actually displays corresponding to each gradation level. In this process, the input level to the liquid crystal panel corresponding to each gradation level is specified, and the LUT is updated to the specified input level. Therefore, in order to generate a highly accurate LUT by calibration, it is desirable that the luminance when the liquid crystal panel is actually displayed corresponding to each gradation level, that is, the luminance of the display surface of the liquid crystal panel can be accurately measured. .

  Therefore, the inventor of the present application is a measuring device that is not affected by the relative ratio of the luminance of the central portion and the peripheral portion of the display surface of the liquid crystal panel and the high-precision viewing angle characteristics, and a measuring device that is easily affected by the viewing angle characteristics. The two relative ratios of the relative ratio are stored in advance for each of the light amounts of the plurality of backlights and the plurality of gradation levels, and are based on the luminance detected at the periphery of the display surface and the stored relative ratio. Thus, a technique for calculating the luminance of the central portion of the display surface has been proposed (see Patent Document 1). By using such a technique, even when both the backlight and the liquid crystal panel have changed over time with respect to arbitrary luminance and gradation characteristics (however, the phenomenon in which the relative ratio changes greatly, for example, the uniformity of the panel is remarkably high). If the sensitivity characteristic has changed due to aging or deterioration of the sensor itself), the brightness at the center of the display surface can be obtained accurately, and when calibration is performed based on such brightness Can generate a highly accurate LUT.

JP 2007-34209 A

  In the technique disclosed in Patent Document 1, the relative ratio of the luminance of the central part and the peripheral part of the display surface of the liquid crystal panel is stored for each gradation level of the video, and corresponds to any gradation level. When the luminance of the peripheral portion of the display surface is obtained, the luminance of the central portion of the display surface is calculated based on the relative ratio corresponding to the gradation level and the obtained peripheral luminance.

  In addition to the above-described processing using the LUT (gamma correction), the liquid crystal display device performs processing such as color tone correction and unevenness correction to achieve desired gradation characteristics, and also adjusts color balance by the user. When the instruction is issued, the correction amount used in each process is changed as appropriate to realize the gradation characteristics according to the instruction from the user.

  When the gradation characteristics are changed, the luminance of the central portion and the peripheral portion of the display surface corresponding to each gradation level also changes, so that the relative ratio of the luminance of the central portion and the peripheral portion of the display surface also changes. Therefore, in the state where the correction amount of each process performed by the liquid crystal display device is not changed, the luminance at the center portion of the display surface is accurate even if calibration (LUT update) is performed using a relative ratio prepared in advance. Since it can be measured (predicted) well, a highly accurate LUT can be generated. However, even though the correction amount of each process performed by the liquid crystal display device is changed, when the calibration is used without changing the relative ratio prepared in advance, the central portion of the display surface is not changed. There is a possibility that the luminance cannot be measured (predicted) with high accuracy. In addition, when such luminance is used, a highly accurate LUT cannot be generated.

  The present invention has been made in view of such circumstances, and an object of the present invention is to display the periphery of the display surface even when the correction amount in various correction processes performed on the video signal is changed. The present invention provides a light emission intensity measuring method, a light emission intensity measuring device, and a computer program that can accurately estimate the light emission intensity at the center from the light emission intensity at the center.

  The light emission intensity measuring method according to the present invention includes a display panel and a backlight, and the light emission intensity measuring method measures light emission intensity from a display surface of a display device that displays an image on the display panel using the backlight as a light source. In the first acquisition step, a plurality of images having a single light emission intensity are sequentially displayed on the display surface, and the light emission intensities at the central portion and the peripheral portion of the display surface are acquired for each image, and the first acquisition step. A storage step of storing correspondence information in which the light emission intensities of the central portion and the peripheral portion of the display surface acquired for each image are associated, and the light emission intensity of the peripheral portion of the display surface is acquired after storing the correspondence information. A second acquisition step, and a calculation step of calculating the light emission intensity at the center of the display surface based on the light emission intensity at the periphery of the display surface and the correspondence information acquired in the second acquisition step. Characterized in that it comprises a.

  In the emission intensity measuring method according to the present invention, the first acquisition step sequentially displays a plurality of images of a single emission intensity on the display surface at a predetermined timing, and for each image, a central portion of the display surface and Peripheral emission intensity is acquired, and the storing step updates the correspondence information every time the first acquisition step acquires the central and peripheral emission intensity of the display surface for each video. And

  In the emission intensity measuring method according to the present invention, the storage step further stores the emission intensity of the backlight when acquiring the emission intensity of the central portion and the peripheral portion of the display surface in the first acquisition step, Based on the light emission intensity of the backlight and the light emission intensity of the backlight stored in the storage step when the light emission intensity of the peripheral portion of the display surface is acquired in the second acquisition step, is stored in the storage step. A change step of changing the correspondence information, wherein the calculation step is based on the emission intensity of the peripheral portion of the display surface acquired in the second acquisition step and the correspondence information changed in the change step. The light emission intensity at the center of the display surface is calculated.

  In the emission intensity measuring method according to the present invention, the first acquisition step sequentially displays a plurality of images having a single emission intensity on the display surface while changing the emission intensity of the backlight stepwise. For each backlight emission intensity, acquire the emission intensity of the central portion and the peripheral portion of the display surface corresponding to each image, and the storing step is the first acquisition step for each backlight emission intensity. Correspondence information that associates the light emission intensities of the central part and the peripheral part of the display surface acquired corresponding to each video is stored, and according to the light emission intensity of the backlight at the time of acquisition in the second acquisition step A selection step for selecting the correspondence information, and the calculation step is based on the emission intensity of the peripheral portion of the display surface acquired in the second acquisition step and the correspondence information selected in the selection step. Te, and calculates the light emission intensity in the central portion of the display surface.

  In the method for measuring light emission intensity according to the present invention, the light emission intensity of the backlight is the light emission acquired at the periphery of the display surface when the image displayed on the display surface is a single image with the maximum light emission intensity. It is characterized by strength.

  The light emission intensity measuring method according to the present invention is characterized in that the light emission intensity of the backlight is a control value for controlling the light emission amount of the backlight.

  The light emission intensity measuring method according to the present invention is characterized in that the light emission intensity is luminance and / or chromaticity.

  The emission intensity measuring device according to the present invention includes a display panel and a backlight, and the emission intensity measuring device that measures the emission intensity from the display surface of the display device that displays an image on the display panel using the backlight as a light source, A first acquisition unit that sequentially displays a plurality of images having a single light emission intensity on the display surface, and acquires the light emission intensities of the central portion and the peripheral portion of the display surface for each image, and the first acquisition unit A storage unit that stores correspondence information that associates the light emission intensities of the central portion and the peripheral portion of the display surface acquired for each video, and after the correspondence information is stored in the storage unit, Based on the second acquisition unit that acquires the emission intensity, the emission intensity acquired by the second acquisition unit, and the correspondence information stored in the storage unit, the emission intensity of the central portion of the display surface is calculated. And a calculation unit. .

  In the emission intensity measuring device according to the present invention, the first acquisition unit sequentially displays a plurality of images having a single emission intensity on the display surface at a predetermined timing, and for each image, a central portion of the display surface and The storage unit updates the correspondence information each time the first acquisition unit acquires the emission intensity of the central part and the peripheral part of the display surface for each image. It is made to do so.

  In the emission intensity measuring device according to the present invention, the storage unit further stores the emission intensity of the backlight when the first acquisition unit acquires the emission intensity of the central part and the peripheral part of the display surface. Based on the light emission intensity of the backlight and the light emission intensity of the backlight stored in the storage unit when the second acquisition unit acquires the light emission intensity of the peripheral part of the display surface, The information processing apparatus further includes a changing unit that changes the correspondence information stored in the storage unit, and the calculation unit includes the emission intensity of the peripheral portion of the display surface acquired by the second acquisition unit and the correspondence information changed by the changing unit. Based on the above, the emission intensity at the center of the display surface is calculated.

  In the emission intensity measuring device according to the present invention, the first acquisition unit sequentially displays a plurality of images having a single emission intensity on the display surface while changing the emission intensity of the backlight stepwise. For each backlight emission intensity, the emission intensity of the central portion and the peripheral portion of the display surface corresponding to each image is obtained, and the storage unit stores the first emission intensity for each backlight emission intensity. Is stored in association with the emission intensity of the central portion and the peripheral portion of the display surface acquired corresponding to each video, and the back when the second acquisition unit acquires The information processing apparatus further includes a selection unit that selects correspondence information according to the light emission intensity of the light, and the calculation unit includes the light emission intensity of the peripheral portion of the display surface acquired by the second acquisition unit and the correspondence information selected by the selection unit. Based on the center of the display surface Wherein the the are calculate the emission intensity.

  The computer program according to the present invention is a computer program for causing a computer to measure the light emission intensity from the display surface of a display device having a display panel and a backlight, wherein the computer has a single light emission intensity on the display surface. When a plurality of images are sequentially displayed, an association step for generating correspondence information in which the light emission intensities of the central portion and the peripheral portion of the display surface obtained for each image are associated, and acquired after the generation of the correspondence information And a calculation step of calculating the light emission intensity at the central portion of the display surface based on the light emission intensity at the peripheral portion of the display surface and the correspondence information generated at the association step.

  In the computer program according to the present invention, the associating step further associates the correspondence information with the light emission intensity of the backlight when the light emission intensities of the central part and the peripheral part of the display surface are acquired, and Based on the emission intensity of the backlight when acquiring the emission intensity of the peripheral portion of the display surface after the generation of the correspondence information and the emission intensity of the backlight associated with the correspondence information in the association step Further, a change step for changing the correspondence information is further performed, and the calculation step is based on the emission intensity of the peripheral portion of the display surface obtained after the generation of the correspondence information and the correspondence information changed in the change step. The light emission intensity at the center of the display surface is calculated.

  In the computer program according to the present invention, the association step may include the step of changing the backlight intensity when the backlight intensity is changed stepwise and a plurality of images having a single emission intensity are sequentially displayed on the display surface. Generating correspondence information that associates the light emission intensities of the central portion and the peripheral portion of the display surface corresponding to each image acquired for each light emission intensity of the light, and after generating the correspondence information in the computer, the display surface A selection step of selecting correspondence information according to the light emission intensity of the backlight when acquiring the light emission intensity of the peripheral portion of the display area, and the calculation step includes the periphery of the display surface acquired after the generation of the correspondence information The light emission intensity at the center of the display surface is calculated based on the light emission intensity of the part and the correspondence information selected in the selection step.

  According to the present invention, a plurality of images having a single light emission intensity are sequentially displayed on the display surface of a display device having a display panel and a backlight, and the light emission intensities at the central portion and the peripheral portion of the display surface are obtained for each image. Then, correspondence information that associates the light emission intensities of the central portion and the peripheral portion of the display surface acquired for each video (video light emission intensity) is stored. When measuring (predicting) the light emission intensity of the display surface, the light emission intensity of the peripheral part of the display surface is acquired in a state where the correspondence information is already stored, and based on the acquired light emission intensity and the correspondence information stored in advance. Then, the light emission intensity at the center of the display surface is calculated. Instead of storing the relative ratio of the luminance (light emission intensity) of the central portion and the peripheral portion of the display surface in association with each gradation level (each light emission intensity) of the image as in the past, the central portion measured in advance. In addition, since the light emission intensity of the peripheral portion itself is stored, the light emission intensity of the central portion of the display surface can be measured (predicted) without depending on the gradation level.

  According to the present invention, each time a plurality of images having a single light emission intensity are sequentially displayed on the display surface of the display device at a predetermined timing, and the light emission intensities at the central portion and the peripheral portion of the display surface are acquired for each image, the memory is stored. Update the corresponding information. Therefore, it is possible to appropriately update the correspondence information used when calculating the light emission intensity at the central portion of the display surface from the light emission intensity at the peripheral portion of the display surface.

  According to the present invention, together with the correspondence information, the light emission intensity of the backlight when the light emission intensities at the central portion and the peripheral portion of the display surface are acquired in order to generate the correspondence information is stored. When measuring (predicting) the light emission intensity of the display surface, first, the light emission intensity of the backlight when obtaining the light emission intensity of the peripheral part of the display surface and the light emission intensity of the backlight stored together with the correspondence information in advance. Based on this, the correspondence information is changed. And the light emission intensity of the peripheral part of a display surface is acquired, and the light emission intensity of the center part of a display surface is calculated based on the acquired light emission intensity and changed correspondence information. Therefore, it is possible to appropriately generate correspondence information according to the light emission intensity of the backlight when obtaining the light emission intensity of the peripheral part of the display surface, and the light emission intensity of the central part of the display surface is calculated based on such correspondence information Is done. This makes it possible to accurately measure the light emission intensity at the central portion of the display surface at any brightness (backlight light emission intensity).

  According to the present invention, while changing the backlight emission intensity in stages, a plurality of images having a single emission intensity are sequentially displayed on the display surface, and the display surface corresponding to each image is displayed for each backlight emission intensity. The correspondence information in which the emission intensity of the central part and the peripheral part of the display surface obtained in correspondence with each image is associated is stored for each emission intensity of the backlight. deep. When measuring (predicting) the light emission intensity of the display surface, first, an image with a predetermined light emission intensity is displayed on the display surface, and according to the light emission intensity of the backlight based on the light emission intensity at the periphery of the display surface at this time. One of the plurality of correspondence information is selected. And the light emission intensity of the peripheral part of a display surface is acquired, and the light emission intensity of the center part of a display surface is calculated based on the acquired light emission intensity and the selected corresponding information. Therefore, it is possible to appropriately select correspondence information according to the light emission intensity of the backlight when obtaining the light emission intensity at the peripheral portion of the display surface, and the light emission intensity at the center portion of the display surface is calculated based on such correspondence information. Is done. This makes it possible to accurately measure the light emission intensity at the center of the display surface regardless of the brightness.

  According to the present invention, the light emission intensity of the backlight is the light emission intensity acquired at the periphery of the display surface when the image displayed on the display surface is a single image with the maximum light emission intensity. That is, for example, when displaying an image with 256 gradations on the display device, the light emission intensity at the periphery of the display surface when an image with a gradation value of 255 is displayed is regarded as the light emission intensity of the backlight.

  According to the present invention, the light emission intensity of the backlight is a control value for controlling the light emission amount of the backlight. That is, for example, a brightness value that can be adjusted by the user or a voltage value given to the backlight is regarded as the light emission intensity of the backlight.

  According to the present invention, the luminance and / or chromaticity of the central portion of the display surface is calculated from the luminance and / or chromaticity of the peripheral portion of the display surface based on correspondence information prepared in advance. Therefore, it is possible to accurately measure (predict) the luminance and / or chromaticity of the central portion of the display surface without depending on the gradation level of the video displayed on the display unit.

  In the present invention, since the emission intensity at the center of the display surface can be measured (predicted) without depending on the gradation level, any gradation characteristic can be obtained by changing the correction amount in each processing performed on the video signal to be displayed. Even when corrected to, the emission intensity at the center of the display surface can be accurately measured. In addition, since the light emission intensity at the central portion of the display surface is calculated by reading the light emission intensity at the central portion corresponding to the light emission intensity at the peripheral portion of the display surface from the correspondence information stored in advance, it is necessary to perform arithmetic processing. In addition, the light emission intensity at the center can be calculated only by the search process for the correspondence information. Note that the emission intensity includes, for example, luminance or chromaticity.

  In the present invention, the correspondence information used when calculating the light emission intensity at the central portion of the display surface from the light emission intensity at the peripheral portion of the display surface can be appropriately updated. Therefore, even when the display panel or the backlight has a secular change, the measurement accuracy of the emission intensity at the central portion of the display surface does not decrease by updating the correspondence information.

  In the present invention, correspondence information according to the light emission intensity of the backlight can be appropriately generated or selected, and the light emission intensity at the center of the display surface is calculated based on such correspondence information. The emission intensity at the center of the display surface can be accurately measured. Therefore, it is possible to accurately measure the light emission intensity at the center of the display surface regardless of the brightness, so even if the user uses the display device with any brightness, the display panel or backlight changes over time. Even if there is a light emission, the emission intensity at the center of the display surface can be measured with high accuracy.

  In the present invention, for example, when displaying an image with 256 gradations on the display device, the correspondence information is obtained based on the emission intensity acquired at the periphery of the display surface when displaying an image with a gradation value of 255. Since generation or selection is performed, generation or selection of correspondence information is facilitated. Further, in the present invention, for example, the correspondence information is generated or selected based on the brightness value or the voltage value, so that the generation or selection of the correspondence information is facilitated.

1 is a schematic perspective view showing an external appearance of a liquid crystal display device according to Embodiment 1. FIG. It is a block diagram which shows the structure of the apparatus for performing the light emission intensity measuring method which concerns on this invention. It is a block diagram which shows the structure of the apparatus for performing the light emission intensity measuring method which concerns on this invention. It is a schematic diagram which shows an example of a correlation table. It is a flowchart which shows the procedure of a correlation process. It is a graph which shows an example of a correlation table. It is a flowchart which shows the procedure of a calibration process. It is a flowchart which shows the procedure of a calibration process. It is a graph which shows an example of the generated correlation information. It is a flowchart which shows the procedure of a LUT update process. FIG. 10 is a schematic diagram illustrating an example of a correlation table according to the second embodiment. It is a flowchart which shows the procedure of a correlation process. It is a flowchart which shows the procedure of a correlation process. It is a flowchart which shows the procedure of a calibration process. It is a flowchart which shows the procedure of a calibration process. It is a block diagram which shows the structure of the liquid crystal display device which concerns on the modification of Embodiment 1,2. FIG. 17 is a block diagram illustrating a modification of the liquid crystal display device having the configuration illustrated in FIG. 16.

  Hereinafter, a light emission intensity measuring method, a light emission intensity measuring apparatus, and a computer program according to the present invention will be specifically described with reference to the drawings showing embodiments thereof. In the following embodiments, an example in which the light emission intensity measuring method according to the present invention is applied to a liquid crystal display device will be described. The light emission intensity measuring method according to the present invention is a light source such as a MEMS (Micro Electro Mechanical Systems) display. It can also be applied to a display device having a separate display.

(Embodiment 1)
Below, the structure of Embodiment 1 for implement | achieving the light emission intensity measuring method which concerns on this invention is demonstrated. FIG. 1 is a schematic perspective view showing the appearance of the liquid crystal display device according to the first embodiment. The liquid crystal display device 1 is configured to display an image by providing a display surface 2 by a liquid crystal panel in front of a main body portion having a substantially rectangular plate shape. Further, the liquid crystal display device 1 is provided with a stand on the back surface, and supports the main body portion so that the display surface 2 is substantially vertical on a desk or a floor.

  In addition, a swing sensor 30 that detects light emission intensity such as luminance or chromaticity at the periphery of the display surface 2 is detachably attached to the upper side of the main body of the liquid crystal display device 1. The swing sensor 30 has a substantially rectangular plate shape, and an optical sensor is disposed in the vicinity of one end portion so that the light receiving surface faces the display surface 2, and the other end portion is pivotally supported to be rotatable. A portion 31 is provided. The moving part 31 is located between the position where the optical sensor faces the peripheral part of the display surface 2 and the position that is accommodated in the accommodating part 32 provided in the main body portion of the swing sensor 30 and does not face the display surface 2. It moves by the power of the DC motor. By automatically moving the moving part 31, it is possible to automatically detect the light emission intensity in the peripheral part of the display surface 2.

  2 and 3 are block diagrams showing the configuration of an apparatus for executing the emission intensity measuring method according to the present invention. The light emission intensity measuring method according to the present invention includes a liquid crystal display device 1 and a swing sensor 30 described above, and a display surface side for detecting light emission intensity such as luminance or chromaticity at the center of the display surface 2 of the liquid crystal display device 1. It is executed by using an external light sensor 40 installed in the PC and a PC 50 for controlling these three devices. The external light sensor 40 is attached to the central portion of the display surface 2 of the liquid crystal display device 1 manually by a user of the liquid crystal display device 1, for example. In addition to this, the external light sensor 40 may be in the form of an optical measuring instrument that images the entire display surface and measures the emission intensity two-dimensionally.

  The liquid crystal display device 1 includes a liquid crystal panel 3, a backlight 4, a control unit 5, a storage unit 6, a RAM (Random Access Memory) 7, an operation unit 8, a signal input unit 9, a backlight drive unit 10, a liquid crystal drive unit 11, and the like. It has. The signal input unit 9 of the liquid crystal display device 1 has a connection terminal connected to an external device such as the PC 50 via a cable, and acquires a video signal input from the external device. The liquid crystal display device 1 displays an image on the display surface 2 of the liquid crystal panel 3 based on the input image signal. The video signal input to the signal input unit 9 may be either an analog signal format or a digital signal format.

  The control unit 5 is connected to each unit in the liquid crystal display device 1 through a bus, and executes various processes such as video display by controlling these operations. The storage unit 6 is a rewritable memory element such as a flash memory or an EEPROM, for example, and stores in advance various programs and data necessary for the operation of the control unit 5, an LUT 6a, and the like. The LUT 6a is a table generated by the CPU 51 of the PC 50. As will be described later, the LUT 6a corresponds to each gradation level and each gradation level so that the ideal light emission intensity stored in the ideal gradation characteristic table 62 is obtained. This is a table in which the input level given to the liquid crystal panel 3 is stored in association with each other. The RAM 7 is a rewritable memory element such as SRAM or DRAM. The control unit 5 loads the program stored in the storage unit 6 to the RAM 7 and executes it, and stores temporary data generated along with the execution of the program in the RAM 7.

  The operation unit 8 has various function keys for operating the liquid crystal display device 1. For example, the operation unit 8 includes various setting keys such as a key for setting the brightness (brightness) of the display surface 2 and a key for setting the color balance of an image displayed on the display surface 2. The operation unit 8 receives user operations on these function keys and notifies the control unit 5, and the control unit 5 controls each unit according to the received user operations and updates the settings.

  The liquid crystal panel 3 has a structure in which a pair of glass substrates are opposed to each other, and a liquid crystal layer, which is a liquid crystal substance, is formed in a gap between the glass substrates. One glass substrate is provided with a plurality of pixel electrodes and TFTs (thin film transistors) each having a drain connected to each pixel electrode, and the other glass substrate is provided with a common electrode. The gate and source of the TFT are connected to the output stages of the gate driver 11a and the source driver 11b of the liquid crystal driving unit 11, respectively.

  The liquid crystal driving unit 11 is controlled by the control unit 5 to drive the liquid crystal panel 3 based on the video signal input to the signal input unit 9. The gate driver 11a of the liquid crystal driving unit 11 selectively applies a voltage to the gates of a large number of TFTs included in the liquid crystal panel 3 according to the input video signal, and the source driver 11b is input to the source of the TFTs. A voltage is applied at a voltage value corresponding to the received video signal.

  In the liquid crystal panel 3, on / off of the TFT of each pixel is controlled by the voltage applied from the gate driver 11a, and the output voltage (input level to the liquid crystal panel 3) input from the source driver 11b is set to each pixel during the on period. By applying to the TFT, the light transmittance determined by the electro-optical characteristics of the liquid crystal substance is controlled, the light transmission from the light source is adjusted, and the image is displayed in gradation. The liquid crystal panel 3 is sandwiched between a pair of polarizing plates (not shown), and a backlight 4 serving as a light source is disposed on the back side thereof. Further, the front side of the liquid crystal panel 3 is exposed to the outside, and the front side forms a display surface 2 on which an image is displayed.

  The backlight 4 is driven by a pulse voltage supplied from the backlight drive unit 10, and the backlight drive unit 10 is controlled by the control unit 5 to pulse according to the brightness set by the user operating the operation unit 8. The voltage pulse width or the like is adjusted and applied to the backlight 4 to adjust the luminance (light quantity) of the backlight 4. Thereby, the brightness on the display surface 2 of the liquid crystal panel 3 can be adjusted.

  The swing sensor 30 attached to the liquid crystal display device 1 includes an optical sensor 33, a DC motor 34, a motor drive unit 35, an I / F (interface) unit 36, and the like. The optical sensor 33 provided in the moving unit 31 includes a light receiving element such as a phototransistor, an A / D conversion circuit, and the like, and emits light such as luminance or chromaticity at the periphery of the display surface 2 of the liquid crystal panel 3. The voltage output from the light receiving element is converted into a digital electric signal by the A / D conversion circuit according to the intensity (for example, luminance in the wavelength band of visible light) and output.

  The DC motor 34 generates power for rotating the moving unit 31 along the display surface 2 of the liquid crystal panel 3, and is driven by a voltage supplied from the motor driving unit 35. The motor drive unit 35 generates a desired voltage, applies it to the DC motor 34, and controls the rotation direction and amount of rotation of the DC motor 34, thereby detecting the position where the light intensity of the display surface 2 is detected by the optical sensor 33 or not. The moving unit 31 is moved to one of the detection positions.

  The optical sensor 33 and the motor drive unit 35 are connected to the I / F unit 36, respectively. The I / F unit 36 is connected to the PC 50 via a cable, and gives the light emission intensity of the display surface 2 detected by the optical sensor 33 to the PC 50 as digital data, and obtains a control command from the PC 50 to drive the motor. Part 35 is given. Thereby, the motor drive unit 35 drives the DC motor 34 and moves the moving unit 31 to detect the light emission intensity by the optical sensor 33.

  The external light sensor 40 detects the light emission intensity of the display surface 2 in the same manner as the light sensor 33 of the swing sensor 30. The external light sensor 40 is not always attached to the liquid crystal display device 1 like the swing sensor 30, but is used by being fixed to the approximate center of the display surface 2 with a double-sided tape or a sucker only when detection is performed. The Specifically, the external light sensor 40 has a correlation between the light emission intensity at the center portion of the display surface 2 and the light emission intensity at the peripheral portion at the time of manufacturing the liquid crystal display device 1, mounting the swing sensor 30 or periodically. It is additionally used when acquiring (correlation information). The external light sensor 40 is connected to the PC 50 only at the time of use, and the measured value (light emission intensity) detected by the external light sensor 40 is given to the PC 50 as digital data.

  The PC 50 includes a CPU (Central Processing Unit) 51, a RAM 52, an operation unit 53, I / F units 54 and 55, a signal output unit 56, a storage unit 60, and the like. The CPU 51 is connected to other hardware units via a bus, performs processing for controlling operations of these units, and executes various programs stored in the storage unit 60. The RAM 52 is a memory element such as SRAM or DRAM, and temporarily stores various programs and data when the CPU 51 performs processing.

  The operation unit 53 is, for example, a mouse and a keyboard. The operation unit 53 receives an operation performed by the user on the PC 50 and notifies the CPU 51 of the operation content. The I / F units 54 and 55 include a connection terminal of a standard such as USB or RS232C, for example, and perform data transmission / reception with an external device. In the example shown in FIG. 3, the swing sensor 30 is always connected to the I / F units 54 and 55, and the external light sensor 40 is connected as necessary. The signal output unit 56 is connected to the liquid crystal display device 1, and outputs a display video signal generated by the processing of the CPU 51 to the liquid crystal display device 1. Thereby, a desired image can be displayed on the display surface 2 of the liquid crystal display device 1.

  The storage unit 60 is a large-capacity storage device such as a hard disk, and although not shown, various programs such as an operating system, application programs, and control programs, data used in these programs, or these programs are generated The stored data is stored. In the first embodiment, the storage unit 60 stores a calibration program 61, an ideal gradation characteristic table 62, a correlation table 64, and the like.

  The ideal gradation characteristic table 62 includes gradation levels (for example, gradation values of 0 to 255) related to video data displayed on the liquid crystal display device 1, and the liquid crystal panel of the liquid crystal display device 1 for each gradation level. 3 is a table in which light emission intensity such as ideal luminance or chromaticity at the time of display is associated and stored. The LUT 6a stored in the storage unit 6 of the liquid crystal display device 1 corresponds to each gradation level and each gradation level so that the ideal emission intensity stored in the ideal gradation characteristic table 62 is obtained. It is a table in which input levels to be given to the liquid crystal panel 3 are stored in association with each other. The control unit 5 of the liquid crystal display device 1 converts the gradation level of each pixel of the video data input from the PC 50 via the signal input unit 9 into an optimal input level to the liquid crystal panel 3 based on the LUT 6a. It outputs to the liquid crystal drive part 11 as a video signal.

  However, when the liquid crystal display device 1 changes over time due to continuous use of the liquid crystal display device 1 and the gradation characteristics of the liquid crystal panel 3 slightly change, or when the user wants to change to the maximum brightness different from the current one, In the conversion from the gradation level to the input level by the LUT 6a stored in the storage unit 6 of the liquid crystal display device 1 in advance, the image may not be displayed with the ideal light emission intensity stored in the ideal gradation characteristic table 62. For this reason, a calibration program 61 for performing processing for updating the LUT 6 a in accordance with the changed gradation characteristics of the liquid crystal panel 3 (hereinafter referred to as calibration processing) is stored in the storage unit 60.

  Therefore, the CPU 51 executes the calibration program 61 and updates the LUT 6a, so that the liquid crystal panel 3 can display an image with an ideal emission intensity. The CPU 51 stores the updated LUT 6a in the storage unit 6 of the liquid crystal display device 1 every time the LUT 6a is updated by performing calibration processing. The calibration process may be performed by the user by operating the operation unit 53, causing the PC 50 to execute the calibration program 61, or may be automatically performed at a predetermined cycle. If it has a function of connecting to a network, it may be performed by remote control using a server computer or the like.

  In the calibration process by the calibration program 61, the light emission intensity at the peripheral portion of the display surface 2 of the liquid crystal display device 1 is detected using the swing sensor 30, and the ideal light emission intensity stored in the ideal gradation characteristic table 62 is obtained. The input level stored in the LUT 6a is updated so as to cancel the difference. However, although the swing sensor 30 is configured to detect the light emission intensity at the peripheral portion of the display surface 2, the calibration process is preferably performed based on the light emission intensity at the center portion of the display surface 2. Therefore, the storage unit 60 stores a correlation table 64 that stores correlation information in which the light emission intensity at the center of the display surface 2 and the light emission intensity at the peripheral part are associated with each other at a specific brightness. Therefore, the calibration program 61 calculates (predicts) the light emission intensity at the central part from the light emission intensity at the peripheral part of the display surface 2 detected by the swing sensor 30 based on the correlation table 64, and calculates the light emission intensity at the central part. The calibration process is performed based on the above.

  FIG. 4 is a schematic diagram illustrating an example of the correlation table 64. The correlation table 64 shows the light emission intensity at the periphery of the display surface 2 detected by the swing sensor 30 and the external light sensor 40 when the image of each gradation level is displayed on the display surface 2 at a specific brightness. 4 is a table in which correlation information associated with the light emission intensity at the center of the display surface 2 is stored. Note that the actual correlation table 64 does not have to include the gradation level item.

  When the liquid crystal display device 1, the swing sensor 30, and the external light sensor 40 are manufactured and sold as a set, the correlation table 64 is obtained by measuring in advance in the manufacturing process using the swing sensor 30 and the external light sensor 40. Create it. When the liquid crystal display device 1, the swing sensor 30, and the external light sensor 40 are individually manufactured and sold, the correlation table 64 may be created by performing measurement when the swing sensor 30 is attached. When the correlation table 64 is created in the manufacturing process, the created correlation table 64 may be provided by being recorded on a recording medium such as a CD-ROM, or stored in the storage unit 60 of the PC 50 and provided together with the PC 50. May be. Further, the user can update the correlation table 64 using the swing sensor 30 and the external light sensor 40. The update of the correlation table 64 is provided as one function (correlation function) of the calibration program 61.

  As shown in the figure, the correlation table 64 stores the results of detection for each gradation value in association with each other. When the liquid crystal panel 3 displays 256 gradations, the swing sensor 30 is provided for each gradation level. Are stored in association with the measured values of the external light sensor 40. When the calibration process is performed by the calibration program 61, the CPU 51 of the PC 50 displays an image having the maximum light emission intensity, that is, an image having a gradation value of 255 on the display surface 2, and the peripheral portion of the display surface 2 at this time is displayed. The emission intensity is detected by the swing sensor 30. Further, the CPU 51 changes the correlation information stored in the correlation table 64 to generate correlation information corresponding to the detected light emission intensity, and refers to the generated correlation information, so that the peripheral portion of the display surface 2 is displayed. The emission intensity at the center corresponding to the emission intensity can be easily obtained.

  Thus, the correlation table 64 includes the measured value of the swing sensor 30 (light emission intensity at the peripheral portion of the display surface 2) and the measured value of the external light sensor 40 corresponding to each measurement value (light emission intensity at the central portion of the display surface 2). ) Are stored in association with each other, the light emission intensity at the center of the display surface 2 can be measured (estimated) without depending on the gradation level. Therefore, even when the correction amount used for various correction processes performed on the video data before being displayed on the liquid crystal panel 3 is changed and the gradation characteristics are corrected, the measured value of the swing sensor 30 is obtained. Based on this, the emission intensity at the center of the display surface 2 can be accurately estimated.

  Next, the emission intensity measuring method according to the present invention will be described based on a flowchart. The light emission intensity measuring method according to the present invention uses the external light sensor 40 and the swing sensor 30 to measure the light emission intensity at the central part and the light emission intensity at the peripheral part of the display surface 2 and update the correlation table 64. And a calibration process for updating the LUT 6a by measuring only the light emission intensity at the peripheral portion of the display surface 2 using only the swing sensor 30 without using the external light sensor 40. The correlation process and the calibration process are executed when the CPU 51 executes the calibration program 61.

  First, the correlation process will be described. FIG. 5 is a flowchart showing the procedure of correlation processing. When performing the correlation process, the external light sensor 40 is attached to a predetermined position (center portion) of the display surface 2 of the liquid crystal panel 3 in advance.

  The CPU 51 activates the swing sensor 30 (S1), and moves the moving unit 31 so that the optical sensor 33 faces the peripheral part of the display surface 2. Next, the CPU 51 controls the liquid crystal display device 1 to adjust the light amount of the backlight 4 and set the brightness of the display surface 2 to a desired brightness (for example, the brightness set by the user via the operation unit 8). (S2). In the correlation processing of the first embodiment, correlation information between the measured value of the swing sensor 30 and the measured value of the external light sensor 40 is obtained corresponding to the desired brightness.

  The CPU 51 sets the input gradation (gradation level) i of the video signal to be displayed on the liquid crystal display device 1 to 0 (S3). Note that the setting of the gradation level may be applied to the entire display surface 2 or may be applied only to a region to be measured by the swing sensor 30 and the external light sensor 40. The same applies to the following processing. The CPU 51 detects the light emission intensity at the peripheral part of the display surface 2 at this time by the swing sensor 30, acquires the measurement value of the swing sensor 30 (S4), and determines the light emission intensity at the center part of the display surface 2 as an external light sensor. 40, and the measured value of the external light sensor 40 is acquired (S5). The CPU 51 stores the acquired measurement value of the swing sensor 30 and the measurement value of the external light sensor 40 in association with each other in the correlation table 64 (S6).

  The CPU 51 determines whether or not the light emission intensity has been measured for all the gradations (for example, the gradation level is 0 to 255) (S7), and if not measured for all the gradations (S7: NO) ), 1 is added to the input gradation i (S8), and the process returns to step S4. The CPU 51 repeats the processes of steps S4 to S8 until the emission intensity is measured at all gradations. As a result, as shown in FIG. 4, the measured value of the swing sensor 30 and the external light sensor 40 at a desired brightness are obtained. The correlation information of the measured values is stored in the correlation table 64. When the emission intensity is measured at all gradations (S7: YES), the CPU 51 performs processing for housing the moving unit 31 of the swing sensor 30 in the housing unit 32, processing for returning the display on the liquid crystal panel 3, and brightness setting. The process is terminated (S9), including a process for restoring the original light and a process for displaying a message prompting the user to remove the external light sensor 40 (S9).

  FIG. 6 is a graph showing an example of the correlation table 64. In FIG. 6, the horizontal axis represents the measured value of the swing sensor 30 for the gradation level of 0 to 255, and the vertical axis represents the measured value of the external light sensor 40 for the gradation level of 0 to 255.

  Next, the calibration process will be described. The correlation table 64 is appropriately updated by the correlation processing described above, and the correlation table 64 is used in the calibration processing, so that the central portion can be calculated from the emission intensity of the peripheral portion of the display surface 2 detected by the swing sensor 30. Can be obtained with high accuracy. 7 and 8 are flowcharts showing the procedure of the calibration process.

  In the PC 50 storing the correlation table 64 updated by the correlation process in the storage unit 60, the CPU 51 activates the swing sensor 30 (S21), and the optical sensor 33 faces the peripheral part of the display surface 2. Thus, the moving unit 31 is moved. Next, the CPU 51 controls the liquid crystal display device 1 to adjust the light amount of the backlight 4 and set the brightness of the display surface 2 to a desired brightness (for example, the brightness set by the user via the operation unit 8) ( S22).

  The CPU 51 sets the input gradation (gradation level) of the video signal to be displayed on the liquid crystal display device 1 to 255 (S23), and the swing sensor 30 detects the light emission intensity at the periphery of the display surface 2 at this time. Then, the measured value of the swing sensor 30 is acquired (S24). Based on the measurement value of the swing sensor 30, the CPU 51 generates correlation information corresponding to the measurement value of the swing sensor 30 at this time from the correlation information stored in the correlation table 64.

Specifically, the CPU 51 reads the measurement value of the swing sensor 30 for the gradation level 255 from the correlation information stored in the correlation table 64, and the display surface 2 at this time for the read measurement value of the swing sensor 30. The ratio of the light emission intensity at the peripheral portion (measured value of the swing sensor 30 acquired in step S24) is calculated (S25). For example, the measured value of the swing sensor 30 for the gradation level 255 in the correlation information stored in the correlation table 64 is 200 cd / m ² , and the measured value of the swing sensor 30 acquired in step S24 is 100 cd / m ^2. Suppose. In this case, the CPU 51 calculates the ratio ½ by the measured value (200) of the swing sensor 30 with respect to the gradation level 255 in the emission intensity (100) / correlation information in the peripheral portion of the display surface 2.

Next, in each combination of the measured value of the swing sensor 30 stored in the correlation table 64 and the measured value of the external light sensor 40, the CPU 51 has a ratio of the measured value of the external light sensor 40 to the measured value of the swing sensor 30. Are respectively calculated (S26). For example, in the correlation table 64 shown in FIG. 4, since the measured value of the swing sensor 30 and the measured value of the external light sensor 40 for the gradation level 255 are both 200 cd / m ² , the CPU 51 swings at the gradation level 255. A ratio 1 of the measurement value of the external light sensor 40 to the measurement value of the sensor 30 is calculated.

  The CPU 51 sequentially multiplies each measured value of the swing sensor 30 stored in the correlation table 64 by the ratio 1/2 calculated in step S25 to calculate a new measured value of the swing sensor 30 (S27). Further, the CPU 51 multiplies the measured values of the new swing sensor 30 sequentially calculated by the respective ratios calculated corresponding to the combinations in step S26, and displays the corresponding values of the new measured values of the swing sensor 30. The light emission intensity at the center of the surface 2 is calculated (S28). The CPU 51 generates correlation information by associating the measured value of the new swing sensor 30 calculated in step S27 with the emission intensity at the center of the display surface 2 calculated in step S28 (S29). The CPU 51 stores the generated correlation information in the RAM 52 or the storage unit 60 and uses it. Thereby, the correlation information optimal for the brightness at the time of calibration can be generated from the correlation information stored in the correlation table 64 in advance.

FIG. 9 is a graph showing an example of the generated correlation information. In FIG. 9, the horizontal axis represents the measured value of the swing sensor 30 with respect to the gradation level of 0 to 255, and the vertical axis represents the measured value of the external light sensor 40 with respect to the gradation level of 0 to 255 (in the central portion of the display surface 2). Luminescence intensity). Note that the example shown in FIG. 9 is based on the correlation information G1 stored in advance in the correlation table 64, and the light emission at the peripheral portion of the display surface 2 when displaying an image with a gradation level of 255 during calibration. The correlation information G2 calculated when the intensity is 100 cd / m ² is shown.

As shown in FIG. 9, when the light emission intensity of the peripheral portion of the display surface 2 corresponding to the gradation level 255 is changed from 200 cd / m ² to 100 cd / m ² by changing the brightness, relatively correlation information 1 Reduce to / 2. By such arithmetic processing, even if any brightness is set, correlation information corresponding to the set brightness can be calculated, and thus high-precision calibration is possible using such correlation information. .

  As described above, when the correlation information corresponding to the brightness at the time of calibration is generated, the CPU 51 sets the input gradation (gradation level) i of the video signal to be displayed on the liquid crystal display device 1 to 0 (S30). The light emission intensity at the periphery of the display surface 2 at this time is detected by the swing sensor 30, and the measured value of the swing sensor 30 is acquired (S31). The CPU 51 acquires the measured value of the swing sensor 30, that is, the light emission intensity at the center portion of the display surface 2 corresponding to the light emission intensity at the peripheral portion of the display surface 2 at this time from the correlation information generated in step S 29. (S32). Specifically, the CPU 51 retrieves the measurement value closest to the measurement value of the swing sensor 30 acquired in step S31 from the measurement value of the swing sensor 30 included in the correlation information generated in step S29, and the retrieved swing sensor. The measured value of the external light sensor 40 corresponding to the measured value of 30 (the emission intensity at the center of the display surface 2) is read out. The CPU 51 stores the acquired emission intensity at the center in the storage unit 60 in association with the gradation level (S33).

  The CPU 51 determines whether or not the light emission intensity has been measured for all the gradations (for example, the gradation level is 0 to 255) (S34), and if not measured for all the gradations (S34: NO) ), 1 is added to the input gradation i (S35), and the process returns to step S31. The CPU 51 repeats the processes of steps S31 to S35 until the emission intensity is measured at all gradations. When the emission intensity is measured at all gradations (S34: YES), the CPU 51 reads the ideal gradation characteristic table 62 stored in the storage unit 60 (S36) and stores it in the storage unit 60 in step S33. The LUT 6a is updated based on the light emission intensity at the center of the display surface 2 for all gradation levels and the gradation characteristics in the ideal gradation characteristic table 62 (S37).

  FIG. 10 is a flowchart showing the procedure of the LUT update process, which is the process performed in step S37 of the flowcharts shown in FIGS. The ideal gradation characteristic table 62 stores the ideal light emission intensity corresponding to the gradation level, and the ideal light emission intensity for the gradation level k in the ideal gradation characteristic table 62 is Tk. (K = 0-255). In addition, regarding the light emission intensity at the center of the display surface 2 stored in the storage unit 60 in step S33, the light emission intensity measured with respect to the gradation level j is set to Lj (j = 0 to 255).

  In the update process of the LUT 6a, first, differences (Tk−Lj) between the ideal emission intensity Tk and the measured emission intensity Lj are calculated for all combinations (S41), and the absolute value | Tk−Lj | A combination of the minimum gradation levels k and j is extracted (S42). From the extraction result, the gradation level k is input to the table, the corresponding gradation level j is stored as an output of the table in the LUT 6a (S43), and the update process is terminated.

  After the update process of the LUT 6a is completed in step S37 in FIG. 8, the CPU 51 includes a process of storing the moving unit 31 of the swing sensor 30 in the storage unit 32, a process of restoring the display of the liquid crystal panel 3, and the like. An end process is performed (S38), and the calibration process ends. In addition, when the CPU 51 of the PC 50 updates the LUT 6 a by the calibration process, the updated LUT 6 a is output from the signal output unit 56 to the liquid crystal display device 1. Then, the control unit 5 of the liquid crystal display device 1 stores the LUT 6a acquired via the signal input unit 9 in the storage unit 6 and updates the LUT 6a.

  As described above, in the first embodiment, the correlation information between the light emission intensity at the central portion of the display surface 2 and the light emission intensity at the peripheral portion of the display surface 2 of the liquid crystal panel 3 is obtained from the gradation levels 0 to 255 by the correlation process. Each time it is stored in the correlation table 64 in advance. Then, the light emission intensity at the peripheral portion of the display surface 2 is detected for each gradation level, and the central portion of the display surface 2 at each gradation level is detected based on the detected light emission intensity at the peripheral portion and the correlation information stored in advance. Is calculated. Since both the input and output of the correlation table 64 are emission intensity, it is possible to measure the emission intensity at the center of the display surface 2 without depending on the gradation level. Therefore, even when various correction amounts in color balance adjustment or the like are changed, the light emission intensity at the center of the display surface 2 is accurately measured at any gradation level without changing the correlation table 64. it can.

  In addition, when performing the calibration process, by adjusting the light emission intensity of the liquid crystal panel 3 to the required light emission intensity based on the light emission intensity calculated accurately, the required floor is obtained regardless of the gradation level. Gradation characteristics can be obtained, and calibration can be performed with high accuracy without being affected by the gradation level. Since the light emission intensity at the center portion of the display surface 2 is calculated based on the correlation table 64 and the measured value of the swing sensor 30, an operation of attaching the external light sensor 40 to the center portion of the display surface 2 of the liquid crystal panel 3 is performed. Therefore, the light emission intensity at the center of the display surface 2 can be measured with high accuracy.

  Further, correlation information corresponding to the user's desired brightness (brightness at the time of correlation) is generated from the correlation information stored in the correlation table 64 in advance, and the generated correlation information and light emission in the peripheral portion of the display surface 2 are generated. Based on the intensity, the light emission intensity at the center of the display surface 2 at the set desired brightness is calculated. Therefore, since it is possible to measure the light emission intensity at the center of the display surface 2 regardless of the brightness, it is possible that the user uses any brightness or the backlight 4 has a secular change. Even if it exists, the emitted light intensity of the center part of the display surface 2 can be measured accurately. When performing calibration processing, the required gradation characteristics can be achieved regardless of the brightness level by adjusting the emission intensity of the liquid crystal panel 3 to the required emission intensity based on the emission intensity calculated accurately. It is possible to perform calibration with high accuracy without being affected by brightness.

  In addition, since the correlation table 64 can be updated using the external light sensor 40, the characteristics of the liquid crystal panel 3 or the backlight 4 change due to aging, etc., and the display characteristics on the display surface 2 change. Even if it exists, the display quality of the liquid crystal display device 1 can be kept high.

The CPU 50 according to the first exemplary embodiment detects the emission intensity of the peripheral portion of the display surface 2 detected when the image of the gradation level 255 is displayed from the correlation information stored in advance in the correlation table 64 each time calibration is performed. Correlation information corresponding to was generated. However, for example, the light emission intensity at the periphery of the display surface 2 detected when the image of the gradation level 255 is displayed matches the measured value of the swing sensor 30 with respect to the gradation level 255 stored in the correlation table 64. When (approximate), a calibration process based on the correlation table 64 may be performed.
That is, when the brightness at the time of the calibration process approximates the brightness when the correlation table 64 is updated (at the time of the correlation process), the calibration is performed using the correlation table 64 as it is without performing the arithmetic process. May be. In this case, since the light emission intensity at the central portion of the display surface 2 is calculated only by the search process for the correlation table 64 without performing the calculation process, the processing speed can be increased.

(Embodiment 2)
Below, the structure of Embodiment 2 for implement | achieving the light emission intensity measuring method which concerns on this invention is demonstrated. In the first embodiment described above, the correlation information of the measured values obtained by the swing sensor 30 and the external light sensor 40 corresponding to the light amount of the predetermined backlight 4 is stored in the correlation table 64, and the backlight 4 at the time of calibration is stored. Based on the light quantity, the correlation information corresponding to the light quantity (brightness) at this time is calculated and used from the correlation information stored in the correlation table 64.

  In the second embodiment, correlation information of measurement values obtained by the swing sensor 30 and the external light sensor 40 is stored in advance in the correlation table 64 for each light quantity of the three types of backlights 4. Correlation information suitable for the brightness is selected from the three correlation information. The hardware configuration of the liquid crystal display device 1, the swing sensor 30, the external light sensor 40, and the PC 50 of the second embodiment is the same as that of the liquid crystal display device 1, the swing sensor 30, the external light sensor 40, and the PC 50 of the first embodiment described above. Since there is, explanation is omitted.

  In the PC 50 of the second embodiment, the configuration of the correlation table 64 stored in the storage unit 60 is different from the correlation table 64 of the first embodiment described above. Specifically, in the storage unit 60 of the PC 50 of the second embodiment, the light emission intensity at the center of the display surface 2 and the light emission intensity at the peripheral part correspond to specific (three types in the second embodiment) brightness. A correlation table 64 for storing the attached correlation information is stored. Therefore, the calibration program 61 calculates (predicts) the light emission intensity at the central part from the light emission intensity at the peripheral part of the display surface 2 detected by the swing sensor 30 based on the correlation table 64, and calculates the light emission intensity at the central part. The calibration process is performed based on the above.

  FIG. 11 is a schematic diagram illustrating an example of the correlation table 64 according to the second embodiment. The correlation table 64 of the second embodiment is a display surface detected by the swing sensor 30 when an image of each gradation level is displayed on the display surface 2 in three types of brightness (high brightness, medium brightness, and low brightness). 2 is a table in which correlation information in which the light emission intensity at the peripheral portion of 2 and the light emission intensity at the center portion of the display surface 2 detected by the external light sensor 40 are associated with each other is stored. Note that the actual correlation table 64 does not have to include the gradation level item.

  Below, the correlation process which PC50 of this Embodiment 2 performs is demonstrated based on a flowchart. 12 and 13 are flowcharts showing the procedure of correlation processing. When performing the correlation process, the external light sensor 40 is attached to a predetermined position (center portion) of the display surface 2 of the liquid crystal panel 3 in advance.

  The CPU 51 activates the swing sensor 30 (S51), and moves the moving unit 31 so that the optical sensor 33 faces the peripheral portion of the display surface 2. Next, the CPU 51 controls the liquid crystal display device 1 to adjust the light amount of the backlight 4 and set the brightness of the display surface 2 to the highest brightness (high brightness) among the predetermined brightnesses ( S52). In the second embodiment, the three types of brightness are sequentially switched when performing the correlation process, so that the measured values of the swing sensor 30 and the external light sensor correspond to the three types of brightness as shown in FIG. Correlation information with 40 measured values can be obtained.

  The CPU 51 sets the input gradation (gradation level) i of the video signal to be displayed on the liquid crystal display device 1 to 0 (S53). The CPU 51 detects the emission intensity of the peripheral part of the display surface 2 at this time by the swing sensor 30, acquires the measured value of the swing sensor 30 (S54), and determines the emission intensity of the central part of the display surface 2 as an external light sensor. 40, and the measured value of the external light sensor 40 is acquired (S55). The CPU 51 stores the acquired measurement value of the swing sensor 30 and the measurement value of the external light sensor 40 in association with each other in the correlation table 64 (S56).

  The CPU 51 determines whether or not the light emission intensity has been measured for all the gradations (for example, the gradation level is 0 to 255) (S57), and if not measured for all the gradations (S57: NO) ), 1 is added to the input gradation i (S58), and the process returns to step S54. The CPU 51 repeats the processing of steps S54 to S58 until the light emission intensity is measured at all gradations. As a result, as shown in FIG. 11, the measured value of the swing sensor 30 and the external light sensor 40 at high brightness are obtained. The correlation information of the measured value is stored in the correlation table 64. If the emission intensity has been measured for all gradations (S57: YES), has the CPU 51 similarly measured the emission intensity for intermediate brightness (medium brightness) among predetermined brightnesses? It is determined whether or not (S59).

  When the measurement of the light emission intensity with respect to the medium brightness has not been performed yet (S59: NO), the CPU 51 controls the liquid crystal display device 1 to adjust the light quantity of the backlight 4, and the brightness of the display surface 2 is set to the medium brightness. Set (S60). And CPU51 transfers a process to step S53, and repeats the process of step S53-S58 about medium brightness. As a result, as shown in FIG. 11, correlation information between the measurement value of the swing sensor 30 and the measurement value of the external light sensor 40 in the medium brightness is stored in the correlation table 64.

  If the emission intensity is measured for the medium brightness (S59: YES), has the CPU 51 also measured the emission intensity for the lowest brightness (low brightness) among the predetermined brightnesses? It is determined whether or not (S61). When the measurement of the light emission intensity with respect to the low brightness has not been performed yet (S61: NO), the CPU 51 controls the liquid crystal display device 1 to adjust the amount of light of the backlight 4 so that the brightness of the display surface 2 is reduced to the low brightness. Set (S62). And CPU51 transfers a process to step S53, and repeats the process of step S53-S58 about low brightness. As a result, as shown in FIG. 11, correlation information between the measurement value of the swing sensor 30 and the measurement value of the external light sensor 40 at low brightness is stored in the correlation table 64.

  When the light emission intensity is measured for low brightness (S61: YES), the CPU 51 performs processing for housing the moving unit 31 of the swing sensor 30 in the housing unit 32, processing for returning the display on the liquid crystal panel 3, and brightness setting. The process is terminated (S63), including a process for restoring the original light and a process for displaying a message prompting the user to remove the external light sensor 40 (S63). Correlation information as shown in FIG. 6 is stored in the correlation table 64 by the correlation processing described above. Note that the correlation information shown in FIG. 6 is an example in high brightness.

  Next, calibration processing performed by the PC 50 according to the second embodiment will be described. The correlation table 64 is appropriately updated by the correlation processing described above, and the correlation table 64 is used in the calibration processing, so that the central portion can be calculated from the emission intensity of the peripheral portion of the display surface 2 detected by the swing sensor 30. Can be obtained with high accuracy. 14 and 15 are flowcharts showing the procedure of the calibration process.

  In the PC 50 storing the correlation table 64 updated by the correlation process in the storage unit 60, the CPU 51 activates the swing sensor 30 (S71), and the optical sensor 33 faces the peripheral part of the display surface 2. Thus, the moving unit 31 is moved.

  The CPU 51 sets the input gradation (gradation level) of the video signal to be displayed on the liquid crystal display device 1 to 255 (S73), and the swing sensor 30 detects the light emission intensity at the periphery of the display surface 2 at this time. Then, the measured value of the swing sensor 30 is acquired (S74). Based on the measurement value of the swing sensor 30, the CPU 51 selects one of the correlation information of high brightness, the correlation information of medium brightness, and the correlation information of low brightness stored in the correlation table 64 (S75). Specifically, the CPU 51 selects the measurement value closest to the measurement value acquired in step S74 among the measurement values of the swing sensor 30 for the gradation level 255 in the correlation information of high brightness, medium brightness, and low brightness. Select the brightness correlation information for the selected measurement. Thereby, the correlation information optimal for the current brightness can be selected from the correlation information generated for each of the three levels of brightness.

  The CPU 51 sets the input gradation (gradation level) i of the video signal to be displayed on the liquid crystal display device 1 to 0 (S76), and the light emission intensity at the peripheral portion of the display surface 2 at this time is detected by the swing sensor 30. Then, the measured value of the swing sensor 30 is acquired (S77). The CPU 51 obtains the measured value of the swing sensor 30, that is, the light emission intensity at the central portion of the display surface 2 corresponding to the light emission intensity at the peripheral portion of the display surface 2 at this time from the correlation information selected in step S75. Obtain (S78). Specifically, the CPU 51 searches for the measured value closest to the measured value of the swing sensor 30 acquired in step S77 from the measured value of the swing sensor 30 included in the correlation information selected in step S75, and searches for the searched swing. The measurement value of the external light sensor 40 corresponding to the measurement value of the sensor 30 is read out. The CPU 51 stores the acquired emission intensity at the center in the storage unit 60 in association with the gradation level (S79).

  The CPU 51 determines whether or not the light emission intensity has been measured for all the gradations (for example, the gradation level is 0 to 255) (S80), and if not measured for all the gradations (S80: NO) ), 1 is added to the input gradation i (S81), and the process returns to step S77. The CPU 51 repeats the processes of steps S77 to S81 until the emission intensity is measured at all gradations. When the emission intensity is measured for all gradations (S80: YES), the CPU 51 reads the ideal gradation characteristic table 62 stored in the storage unit 60 (S82) and stores it in the storage unit 60 in step S79. The LUT 6a is updated based on the light emission intensity at the center of the display surface 2 for all gradation levels and the gradation characteristics in the ideal gradation characteristic table 62 (S83). The update process of the LUT 6a is the same as the process described based on FIG.

  After the update process of the LUT 6a is completed, the CPU 51 performs an end process including a process of storing the moving unit 31 of the swing sensor 30 in the storage unit 32, a process of returning the display of the liquid crystal panel 3 and the like (S84). Then, the calibration process is terminated.

  As described above, in the second embodiment, the correlation information between the light emission intensity at the center portion and the light emission intensity at the peripheral portion of the display surface 2 of the liquid crystal panel 3 is obtained from the gradation levels 0 to 255 by the correlation process. Each time it is stored in the correlation table 64 in advance. Then, the light emission intensity at the peripheral portion of the display surface 2 is detected for each gradation level, and the central portion of the display surface 2 at each gradation level is detected based on the detected light emission intensity at the peripheral portion and the correlation information stored in advance. Is calculated. Since both the input and output of the correlation table 64 are emission intensity, it is possible to measure the emission intensity at the center of the display surface 2 without depending on the gradation level. Therefore, even when various correction amounts in color balance adjustment or the like are changed, the light emission intensity at the center of the display surface 2 is accurately measured at any gradation level without changing the correlation table 64. it can.

  In addition, when performing the calibration process, by adjusting the light emission intensity of the liquid crystal panel 3 to the required light emission intensity based on the light emission intensity calculated accurately, the required floor is obtained regardless of the gradation level. Gradation characteristics can be obtained, and calibration can be performed with high accuracy without being affected by the gradation level. Since the light emission intensity at the center portion of the display surface 2 is calculated based on the correlation table 64 and the measured value of the swing sensor 30, an operation of attaching the external light sensor 40 to the center portion of the display surface 2 of the liquid crystal panel 3 is performed. Therefore, the light emission intensity at the center of the display surface 2 can be measured with high accuracy.

  Further, correlation information between the light emission intensity at the center portion and the light emission intensity at the peripheral portion of the display surface 2 of the liquid crystal panel 3 is stored in advance for each different brightness, and the correlation information corresponding to the user's desired brightness is selected. Based on the selected correlation information and the light emission intensity at the periphery of the display surface 2, the light emission intensity at the center of the display surface 2 at the set desired brightness is calculated. Therefore, since it is possible to measure the light emission intensity at the center of the display surface 2 regardless of the brightness, it is possible that the user uses any brightness or the backlight 4 has a secular change. Even if it exists, the emitted light intensity of the center part of the display surface 2 can be measured accurately. When performing calibration processing, the required gradation characteristics can be achieved regardless of the brightness level by adjusting the emission intensity of the liquid crystal panel 3 to the required emission intensity based on the emission intensity calculated accurately. It is possible to perform calibration with high accuracy without being affected by brightness.

  In addition, since the correlation table 64 can be updated using the external light sensor 40, the characteristics of the liquid crystal panel 3 or the backlight 4 change due to aging, etc., and the display characteristics on the display surface 2 change. Even if it exists, the display quality of the liquid crystal display device 1 can be kept high.

  In the second embodiment, the correlation information corresponding to the three brightnesses of high brightness, medium brightness, and low brightness is stored in the correlation table 64. However, the number of brightnesses is not limited to this. Absent. For example, correlation information corresponding to all the brightness that can be taken by the liquid crystal display device 1 may be generated and stored in the correlation table 64. As a result, calibration can be performed using the correlation information optimal for the brightness during the calibration process, so that calibration with higher accuracy is possible.

  In the first and second embodiments described above, the update (correlation processing) of the correlation table 64 is performed by the calibration program 61. However, the configuration is not limited to this, and another dedicated program may be performed. In the first and second embodiments, the PC 50 performs the calibration process and the correlation process. However, the present invention is not limited to this, and the liquid crystal display device 1 may perform part or all of these processes. The swing sensor 30 may perform these processes.

  FIG. 16 is a block diagram illustrating a configuration of a liquid crystal display device 101 according to a modification of the first and second embodiments. The liquid crystal display device 101 according to the modified example includes an I / F unit 54 that connects the swing sensor 30 and an I / F unit 55 that connects the external light sensor 40 in addition to the components of the liquid crystal display device 1 shown in FIG. And a control unit 105 that controls these operations. In addition to the LUT 6a, the storage unit 6 stores a calibration program 61, an ideal gradation characteristic table 62, a correlation table 64, and the like.

  With such a configuration, the liquid crystal display device 101 performs processing for converting the gradation level of the video signal supplied from the PC 150 to a gradation level suitable for the liquid crystal panel 3 by the LUT 6a and displaying the video, and also the above-described collection. Calibration processing (correlation table 64 update processing), calibration processing, and the like. As described above, the liquid crystal display device 101 may perform the correlation processing, the calibration processing, and the like instead of being performed by the PC 150.

  In the first and second embodiments, the swing sensor 30 is a separate device from the liquid crystal display device 1 and the swing sensor 30 is attached to the liquid crystal display device 1 for detection. However, the present invention is not limited to this. The swing sensor 30 may be built in the liquid crystal display device 1. FIG. 17 is a block diagram showing a modification of the liquid crystal display device 101 having the configuration shown in FIG. A liquid crystal display device 101 shown in FIG. 17 includes a motor drive unit 35 and a DC motor 34 instead of the I / F unit 54 in the liquid crystal display device 101 shown in FIG. Moreover, the moving part 31 to which the optical sensor 33 is attached is provided in the upper bezel part of the liquid crystal panel 3, for example. Then, the DC motor 34 moves the moving part 31 from the bezel part to an appropriate position on the periphery of the display surface 2 by driving the motor driving part 35, so that the optical sensor 33 attached to the moving part 31 performs display. It is possible to detect the light emission intensity at the periphery of the surface 2.

  In FIG. 17, the information stored in the storage unit 6 is not shown, but the storage unit 6 includes the LUT 6a, the calibration program 61, the ideal gradation characteristics, as in the configuration shown in FIG. A table 62, a correlation table 64, and the like are stored. The configuration in which the swing sensor 30 is built in the liquid crystal display device 1 is not limited to the configuration shown in FIG. 17, and the swing sensor 30 may be built in the liquid crystal display device 1 having the configuration shown in FIG. 2.

  In the first and second embodiments, the LUT 6 a that is sequentially updated by the PC 50 performing calibration processing is sequentially output to the liquid crystal display device 1, and gradation characteristic conversion based on the LUT 6 a is performed by the liquid crystal display device 1. It was. However, after the PC 50 stores the LUT 6a in the storage unit 60 and converts the gradation level of each pixel of the video data to the optimum input level to the liquid crystal panel 3 based on the LUT 6a, the signal output unit 56 as a video signal. To the liquid crystal display device 1.

  In the first and second embodiments, at the time of calibration, the gradation value of the image displayed on the liquid crystal display device 1 is set to 255, and the light emission intensity at the peripheral portion of the display surface 2 at this time is detected by the swing sensor 30 and obtained. Based on the emitted light intensity and the measured value of the swing sensor 30 corresponding to the gradation value 255 of each correlation information stored in the correlation table 64, correlation information appropriate for the brightness at this time is generated or selected. It was. In addition to such a configuration, for example, current brightness information may be acquired from the liquid crystal display device 1, and correlation information appropriate for the acquired brightness may be generated or selected. As the brightness information, for example, a brightness value indicating the brightness adjusted by the user, an output voltage value given to the backlight 4 by the backlight driving unit 10, and the like can be used.

  In the first and second embodiments, the case where the number of gradations which is the total number of gradation values is 256 has been described. However, the number of gradations is not limited to this, and other gradation numbers can be used. . For example, among the 256 gradations, only 50 points may be measured or correlated, and the gradation between them may be acquired by interpolation processing.

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 2 Display surface 3 Liquid crystal panel (display panel)
4 Backlight 6 Storage 6a LUT
30 Swing sensor 40 External light sensor 50 PC (luminescence intensity measuring device)
51 CPU (acquisition part, calculation part, change part, selection part)
61 Calibration program 64 Correlation table (storage unit)

Claims (14)

In a light emission intensity measuring method comprising a display panel and a backlight, and measuring light emission intensity from a display surface of a display device that displays an image on the display panel using the backlight as a light source,
A first acquisition step of sequentially displaying a plurality of images having a single light emission intensity on the display surface, and acquiring the light emission intensities of a central portion and a peripheral portion of the display surface for each image;
A storage step for storing correspondence information in which the emission intensity of the central portion and the peripheral portion of the display surface acquired for each video in the first acquisition step is associated;
A second acquisition step of acquiring the emission intensity of the peripheral portion of the display surface after storing the correspondence information;
A calculation step of calculating a light emission intensity at a central portion of the display surface based on the light emission intensity of the peripheral portion of the display surface and the correspondence information acquired in the second acquisition step. Strength measurement method. In the first acquisition step, a plurality of images having a single light emission intensity are sequentially displayed on the display surface at a predetermined timing, and for each image, the light emission intensities of the central portion and the peripheral portion of the display surface are acquired,
2. The light emission according to claim 1, wherein the storing step updates the correspondence information every time the first and second acquisition steps acquire the light emission intensity of the central portion and the peripheral portion of the display surface for each image. Strength measurement method. The storage step further stores the light emission intensity of the backlight when acquiring the light emission intensity of the central portion and the peripheral portion of the display surface in the first acquisition step,
Based on the light emission intensity of the backlight and the light emission intensity of the backlight stored in the storage step when the light emission intensity of the peripheral part of the display surface is acquired in the second acquisition step, is stored in the storage step. A change step for changing the corresponding correspondence information,
The calculation step calculates the light emission intensity at the center portion of the display surface based on the light emission intensity at the peripheral portion of the display surface acquired at the second acquisition step and the correspondence information changed at the change step. The method of measuring luminescence intensity according to claim 1 or 2. In the first acquisition step, a plurality of images having a single light emission intensity are sequentially displayed on the display surface while gradually changing the light emission intensity of the backlight, and each image is displayed for each light emission intensity of the backlight. Obtaining the emission intensity of the central part and the peripheral part of the display surface corresponding to
The storing step stores, for each emission intensity of the backlight, correspondence information in which the emission intensity of the central part and the peripheral part of the display surface acquired corresponding to each image in the first acquisition step is associated. And
A selection step of selecting correspondence information according to the emission intensity of the backlight at the time of acquisition in the second acquisition step;
The calculation step calculates the light emission intensity at the center portion of the display surface based on the light emission intensity at the peripheral portion of the display surface acquired at the second acquisition step and the correspondence information selected at the selection step. The method of measuring luminescence intensity according to claim 1 or 2.   The light emission intensity of the backlight is a light emission intensity acquired at a peripheral portion of the display surface when an image displayed on the display surface is an image having a single maximum light emission intensity. 5. The method for measuring luminescence intensity according to 3 or 4.   The light emission intensity measuring method according to claim 3 or 4, wherein the light emission intensity of the backlight is a control value for controlling the light emission amount of the backlight.   The method of measuring emission intensity according to any one of claims 1 to 6, wherein the emission intensity is luminance and / or chromaticity. In a light emission intensity measuring device that includes a display panel and a backlight, and that measures light emission intensity from a display surface of a display device that displays an image on the display panel using the backlight as a light source,
A first acquisition unit configured to sequentially display a plurality of images having a single light emission intensity on the display surface, and to acquire the light emission intensities of a central portion and a peripheral portion of the display surface for each image;
A storage unit that stores correspondence information that associates the emission intensity of the central portion and the peripheral portion of the display surface acquired by the first acquisition unit for each video;
After the correspondence information is stored in the storage unit, a second acquisition unit that acquires emission intensity of a peripheral part of the display surface;
A light emission intensity comprising: a light emission intensity acquired by the second acquisition unit; and a calculation unit that calculates the light emission intensity of the central portion of the display surface based on the correspondence information stored in the storage unit. measuring device. The first acquisition unit sequentially displays a plurality of images having a single light emission intensity on the display surface at a predetermined timing, and acquires the light emission intensities of the central portion and the peripheral portion of the display surface for each image. And
9. The storage unit is configured to update the correspondence information each time the first acquisition unit acquires the light emission intensity of the central portion and the peripheral portion of the display surface for each video. The luminescence intensity measuring apparatus according to 1. The storage unit is configured to further store the emission intensity of the backlight when the first acquisition unit acquires the emission intensity of the central part and the peripheral part of the display surface,
Based on the light emission intensity of the backlight and the light emission intensity of the backlight stored in the storage unit when the second acquisition unit acquires the light emission intensity of the peripheral part of the display surface, the storage unit It further comprises a changing unit for changing the stored correspondence information,
The calculation unit calculates the light emission intensity at the center of the display surface based on the light emission intensity at the periphery of the display surface acquired by the second acquisition unit and the correspondence information changed by the change unit. The luminescence intensity measuring device according to claim 8 or 9, wherein The first acquisition unit sequentially displays a plurality of images having a single light emission intensity on the display surface while changing the light emission intensity of the backlight step by step, and each image is displayed for each light emission intensity of the backlight. The emission intensity of the central part and the peripheral part of the display surface corresponding to is obtained,
The storage unit stores, for each emission intensity of the backlight, correspondence information that associates the emission intensity of the central portion and the peripheral portion of the display surface acquired by the first acquisition unit corresponding to each image. As a configuration,
A selection unit that selects correspondence information according to the emission intensity of the backlight when the second acquisition unit acquires;
The calculation unit calculates the light emission intensity at the center of the display surface based on the light emission intensity at the periphery of the display surface acquired by the second acquisition unit and the correspondence information selected by the selection unit. The luminescence intensity measuring device according to claim 8 or 9, wherein In a computer program for causing a computer to measure light emission intensity from a display surface of a display device having a display panel and a backlight,
In the computer,
A correspondence step of generating correspondence information in which the light emission intensities of the central portion and the peripheral portion of the display surface obtained for each video are associated when a plurality of images having a single light emission intensity are sequentially displayed on the display surface. When,
A calculation step of calculating the light emission intensity at the center of the display surface based on the light emission intensity of the peripheral portion of the display surface acquired after the generation of the correspondence information and the correspondence information generated in the association step; A computer program characterized by causing The association step further associates the light emission intensity of the backlight when the light emission intensity of the central portion and the peripheral portion of the display surface is acquired with the correspondence information,
The backlight emission intensity associated with the correspondence information in the association step and the emission intensity of the peripheral portion of the display surface after the correspondence information is generated in the computer. And further executing a changing step for changing the correspondence information,
The calculating step calculates the light emission intensity at the central portion of the display surface based on the light emission intensity of the peripheral portion of the display surface acquired after the generation of the correspondence information and the correspondence information changed in the changing step. The computer program according to claim 12, characterized in that: The association step is acquired for each backlight emission intensity when a plurality of images having a single emission intensity are sequentially displayed on the display surface while changing the emission intensity of the backlight stepwise. Generating correspondence information in which the light emission intensities of the central portion and the peripheral portion of the display surface corresponding to each video are associated,
After the generation of the correspondence information, the computer further causes a selection step of selecting correspondence information according to the emission intensity of the backlight when acquiring the emission intensity of the peripheral portion of the display surface,
The calculating step calculates the light emission intensity at the center portion of the display surface based on the light emission intensity at the peripheral portion of the display surface acquired after the generation of the correspondence information and the correspondence information selected at the selection step. The computer program according to claim 12, characterized in that:

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