JP5227539B2 - Output value setting method, output value setting device, and display device - Google Patents

Description

  The present invention relates to a display device that displays an image based on an input signal, and a display device that stores an output value related to driving of the display unit with respect to an input gradation of the input signal. The present invention relates to an output value setting method, an output value setting device and a display device for setting an output value by this method.

  2. Description of the Related Art Conventionally, a display device that includes a display unit such as a liquid crystal panel and displays on a display unit in accordance with a video signal supplied from an external device such as a PC (personal computer) or a playback device has been widely used. In recent years, display devices are used for various purposes. For example, in the case of a display device used for medical purposes, a display device that performs multi-gradation display is required. For this reason, a technique for increasing the display gradation of the display device has been researched and developed. One of the techniques for increasing the display gradation is an FRC (frame rate control) technique.

  FIG. 8 is a schematic diagram showing a configuration of a conventional display device equipped with FRC technology. In the figure, reference numeral 105 denotes a display panel. The display device displays a video by driving the display panel 105 in accordance with a video signal supplied from an external device such as a PC or a playback device (not shown). is there. The video signal given from the external device is a signal having 8-bit information (input gradation) for each of R (red), G (green), and B (blue), and the display panel 105 has RGB colors. Each 8-bit gradation (256 gradations) is displayed. However, the illustrated display device has a function of performing multi-gradation display by the above-described FRC technique, and includes a color arithmetic circuit 101, a LUT (Look Up Table) 102, and an FRC circuit 103 for this purpose. Yes.

  Each 8-bit RGB input signal from an external device is applied to the color arithmetic circuit 101. The color arithmetic circuit 101 adjusts the input gradation so that a given 8-bit input signal has a desired color temperature. At this time, the color calculation circuit 101 performs matrix calculation including multiplication and division. In order to hold the decimal number that cannot be expressed in 8 bits and the decimal number generated by multiplication and division in the calculation result, the 8-bit The operation result is output with higher bit precision, for example, 10 bit precision. The 10-bit signal output from the color arithmetic circuit 101 is given to the LUT 102. The LUT 102 is a table for so-called γ correction processing in which 10-bit output values corresponding one-to-one to 10-bit input values are stored in advance, and a 10-bit signal supplied from the color arithmetic circuit 101 is displayed on the display panel. A signal corresponding to the characteristic 105 is converted by referring to the table, and the converted 10-bit signal is output to the FRC circuit 103.

  The FRC technique is a technique for switching and displaying frames of a plurality of different gradations in a short period of time that cannot be recognized by humans, and displaying pseudo gradations using an afterimage effect. For example, when the display device is configured to display 60 frames of video on the display panel 105 per second, an 8-bit gradation is obtained by changing the display gradation using 4 frames with a period of 4/60 seconds. An image display with 10-bit accuracy can be performed using the display panel 105 that performs display. The FRC circuit 103 of the display device generates an 8-bit signal for performing display with pseudo 10-bit accuracy in 4 frames based on the 10-bit signal supplied from the LUT 102 and supplies the generated signal to the drive circuit 104. It is like that. The drive circuit 104 displays an image by applying an analog signal having a voltage value corresponding to the 8-bit signal supplied from the FRC circuit 103 to the display panel 105.

  As another technique for increasing the display gradation, for example, in Patent Document 1, n-bit digital image data is converted into n + m bits using a γ correction table, and an image is displayed using an n + m-bit D / A converter. By performing the above, a liquid crystal display device has been proposed in which a display image has multiple gradations. The γ correction table used by this liquid crystal display device is created by the following procedure. First, the transmittance of the liquid crystal display device is measured, a graph showing the input voltage dependency of the transmittance with the measured transmittance as the vertical axis and the input voltage as the horizontal axis can be output by the D / A converter. Plot the voltage value on the horizontal axis of the graph. Next, the transmittance of the target n-bit gradation display is plotted on the vertical axis, a line is drawn from this point to the transmittance curve of the graph, and a perpendicular line is drawn from the intersection with the curve to the horizontal axis. The n + m-bit point closest to the intersection of the perpendicular and the horizontal axis can be used as data to be converted by the γ correction table.

In Patent Document 2, a backlight control device that adjusts the brightness of the backlight of the liquid crystal display device based on the measurement results of the luminance characteristic, the color characteristic, and the gradation property of the liquid crystal display device, and the measurement result. In addition, there has been proposed a liquid crystal monitor device that is provided with a data conversion circuit that corrects color display data and outputs the corrected data to a liquid crystal display device, thereby suppressing display quality deterioration due to characteristic variations. This liquid crystal monitor device has a color measurement device for measuring luminance characteristics, color characteristics, and gradation characteristics, and can set the output value of the gradation conversion table of the data conversion circuit based on the measurement result. it can.
Japanese Patent Laid-Open No. 8-2272783 JP 2001-147667 A

  For example, in a conventional display device, the circuit accuracy may be reduced or the cost may be reduced by reducing the processing accuracy of the color arithmetic circuit 101 from 10 bits to 8 bits. In this case, in the calculation by the color calculation circuit 101, information below the decimal is discarded, so that the display gradation of the display panel 105 is lowered even if the FRC technique is used.

  FIG. 9 is a schematic diagram for explaining a decrease in display gradation due to a decrease in processing accuracy of the color arithmetic circuit 101. In FIG. 9, for simplification of description, the input gradation is set to 6 gradations of 0 to 5, the processing accuracy of the color arithmetic circuit 101 is 3 bits or 2 bits, and the display panel 105 for the input gradation is displayed. The graph shows the display characteristics (output level). Further, (a) shows a case where the processing accuracy of the color arithmetic circuit 101 is 3 bits, and (b) shows a case where the processing accuracy is 2 bits. The broken line in the graph is the target display characteristic, and the solid line is the actual display characteristic. From the graph shown in the figure, when the processing accuracy of the color arithmetic circuit 101 is high, the difference between the target display characteristic and the actual display characteristic is small (see FIG. 9A), but when the processing accuracy is low, the target display characteristic is small. It can be seen that the difference between the display characteristics and the actual display characteristics is large, and the display gradation is lowered (see FIG. 9B).

  Therefore, in the conventional display device, there is a problem that it is not easy to achieve both reduction in circuit scale or cost reduction and multi-gradation video display on the display panel 105.

  In addition, the liquid crystal display device described in Patent Document 1 needs to create a γ correction table for converting n-bit digital image data into n + m bits. For this purpose, the transmittance of the liquid crystal display device is measured to measure the transmittance. It is necessary to create a graph showing the input voltage dependency of. Since there are individual variations in the characteristics of the liquid crystal display device, it is desirable to create a graph and a γ correction table for each liquid crystal display device. However, since it takes time to measure the transmittance, the manufacturing cost of the liquid crystal display device There is a problem that increases. Similarly, the liquid crystal monitor device described in Patent Document 2 can set the gradation conversion table by measuring the luminance characteristic, the color characteristic, and the gradation characteristic by the color measurement device, but it takes time for measurement and setting. There is a problem that it takes.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a reference when setting an output value related to driving of a display unit (display panel) with respect to an input gradation. By measuring the display characteristics of the reference display unit of the display device in detail in advance and determining the output value based on this display characteristic and the display characteristic value easily measured by the display unit of the display device to be set An output value setting method, an output value setting device, and a display capable of setting an output value for multi-gradation display without requiring time for setting an output value for a storage unit such as a table included in the display device To provide an apparatus.

An output value setting method according to the present invention is an output value setting method for setting an output value related to driving of a display unit for an input gradation given for each of a plurality of colors. Measurement of luminance and chromaticity change characteristics when the input gradation is changed by aligning colors, and luminance and chromaticity characteristics when the input gradation is changed to a single color display of each color as display characteristics And measuring the luminance and chromaticity of the display unit as a display characteristic value with respect to a predetermined input gradation in which all colors are aligned and a predetermined input gradation in which each color is displayed in a single color on the display unit to be set. Based on the luminance and chromaticity measured as values, the emission intensity that enables display at a predetermined color temperature on the display unit to be set is calculated, and the calculated luminance and luminance measured as the display characteristic value are calculated. For each color with emission intensity according to chromaticity Calculating the rate for the corresponding relationship between the input gradation and brightness of each color corresponding to the predetermined gamma value, the luminance is adjusted according to the ratio, the correspondence relation between the input gradation and adjusted brightness The setting target display characteristics of the input gradation and luminance for each color in the setting target display unit are set, and the setting target display unit is driven based on the setting target display characteristics and the measured display characteristics of the reference display unit. The output value is determined, and the determined output value is stored in association with the input gradation.
Further, the output value setting method according to the present invention calculates the emission intensity for all gradations for each color based on the brightness and chromaticity measured as the display characteristics of the reference display unit, and the determination of the output value is as follows: The luminance corresponding to one input gradation is acquired from the setting target display characteristic , the emission intensity approximate to the luminance acquired from the setting target display characteristic is acquired from the display characteristic of the reference display unit, and the acquired light emission The process of acquiring the input gradation corresponding to the intensity from the display characteristics of the reference display unit and determining the acquired input gradation as an output value is performed for all gradations.

In the output value setting method according to the present invention, the emission intensity calculated based on the display characteristics of the reference display unit is increased to the number of gradations equal to or greater than the number of gradations of the input gradation by interpolation processing, The output value is determined based on the calculated setting target display characteristic and the result of the interpolation process .

The output value setting method according to the present invention is characterized in that the determined output value is stored in a table that outputs one output value associated with a given input gradation .

Further, in the output value setting method according to the present invention, the measurement of display characteristics when the input gradation is changed by aligning all the colors of the reference display unit is performed over the input gradation over all gradations that can be input. It is characterized by changing the key .

In the output value setting method according to the present invention, the display characteristic value of the display unit to be set is measured by measuring the luminance and chromaticity of the display unit with respect to the maximum input gradation.

The output value setting device according to the present invention is a display device including a display unit and a storage unit that stores an output value related to driving of the display unit with respect to an input gradation given for each of a plurality of colors. In the output value setting device that sets the output value in the storage unit, the change in luminance and chromaticity when the input gradation is changed by aligning all colors in the reference display unit of the display device that is the reference for setting. All the colors are aligned in the display unit of the display device of the setting target display device and the means for measuring the characteristics and the characteristics of the luminance and chromaticity when changing to the input gradation to be monochromatic display of each color. Based on the luminance and chromaticity measured as the display characteristic value, the means for measuring the luminance and chromaticity of the display unit with respect to the predetermined input gradation and the predetermined input gradation to be monochromatic display of each color, Predetermined on the display unit of the target display device Means for calculating emission intensity enabling display at temperature; means for calculating a ratio for each color between the calculated emission intensity and the emission intensity according to the luminance and chromaticity measured as the display characteristic value; against correspondence between input gradation and brightness of each color in accordance with the gamma value, the luminance is adjusted according to the ratio of the input tone and adjusting luminance of the display device of the correspondence between the set target means to be set target display characteristics of the input gradation and brightness of each color in the display unit, based on the display characteristics of the reference display section that the set target target display characteristics and measurements, the display of the display device of the setting target Means for determining an output value related to the driving of the unit, and the determined output value is stored in the storage unit in association with the input gradation.

Further, the display device according to the present invention is a display device including a display unit and a storage unit that stores an output value related to driving of the display unit with respect to an input gradation given for each of a plurality of colors. In the reference display section of the other display device, the characteristics of luminance and chromaticity changes when all the colors are aligned and the input gradation is changed, and the input gradation is changed to a single color display of each color. Means for acquiring the measured luminance and chromaticity characteristics as display characteristics, and the luminance and chromaticity of the display unit with respect to a predetermined input gradation in which all colors are aligned and a predetermined input gradation for monochrome display of each color And a means for calculating emission intensity that enables display at a predetermined color temperature on the display unit based on the luminance and chromaticity measured as the display characteristic value. Measured as emission intensity and display characteristic value Means for calculating the ratio of each color of the light emission intensity corresponding to the luminance and chromaticity were, for the corresponding relationship between the input gradation and brightness of each color corresponding to the predetermined gamma value, the luminance in the ratio The display unit adjusts the correspondence between the input gradation and the adjusted luminance as a target display characteristic for setting the input gradation and luminance for each color in the display unit, the target display characteristic for setting and the acquired other Means for determining an output value related to driving of the display unit based on display characteristics of the display device, and the determined output value is stored in the storage unit in association with an input gradation. It is characterized by.

  In the present invention, the display characteristic with respect to the input gradation is measured in detail in advance in the reference display section of the reference display device. Since only one or a small number of reference display sections are to be measured, even when measuring in detail, the manufacturing process of other display devices is not affected. When setting the output value, first, the display characteristic value of the display unit to be set for a predetermined input gradation is measured on the display device to be set. It is not necessary to perform measurement for all the input gradations, and it is only necessary to perform measurement for a predetermined input gradation. Next, the setting target display characteristic of the setting target display unit is calculated based on the predetermined target display characteristic given by the design target or the product specification and the display characteristic value measured for the predetermined input gradation. . Furthermore, based on the calculated setting target display characteristic and the display characteristic measured by the reference display unit, an output value is determined by performing arithmetic processing such as approximation or interpolation, and stored in the storage unit of the setting target display device. Remember. In the display device to be set, the output value can be set only by performing measurement for a predetermined input gradation, and therefore the output value can be set in a short time. In addition, the display gradation performed using the output value set by the display device to be set can be increased by performing detailed measurement on the reference display unit.

  In the present invention, the output value determined from the measurement result of the characteristic of the reference display unit and the characteristic of the display unit to be set is stored in a table that outputs one output value for a given input gradation. To do. By providing this table in the display device to be set, when performing the display process, it is possible to easily obtain and display the output value without performing complicated calculations.

  In the present invention, when measuring the display characteristics of the reference display unit included in the reference display device, the measurement is performed for all gradations input to the reference display unit. Thereby, since a detailed measurement result with high accuracy can be given to the display device to be set, when determining the output value, the output value is determined based on the accurate measurement result on the reference display unit. Therefore, the display gradation of the display device using this output value can be further increased.

  Further, in the present invention, when input gradations are given for each of a plurality of colors, display characteristics in which the input gradations of each color are aligned and changed for all gradations, and the input gradation of one color is set to the maximum input gradation. Then, the reference display unit is measured for the display characteristics when the input gradation of other colors is the minimum input gradation. As a result, the display characteristics of each color with respect to the input gradation can be accurately calculated by calculation such as interpolation for all gradations.

  In the present invention, the number of gradations of the measurement result is increased more than the number of gradations of the input gradation by performing an interpolation process on the measurement result of the display characteristics of the reference display unit. As a result, the number of gradations can be increased by increasing the output value, and the display device can perform multi-gradation display using FRC technology or the like.

  In the present invention, when the measurement is performed on the display device to be set, the display characteristic value at the maximum input gradation input to the setting target panel as the predetermined input gradation is measured. The measurement time and the setting time are shortened by making the measurement on the display device to be set only the maximum input gradation.

  According to the present invention, the display characteristics of the reference display unit of the reference display device are previously measured in detail, and the display characteristics and the display characteristic values easily measured by the display unit of the display device to be set are obtained. By setting the output value based on this, even if the measurement of the reference display unit is performed in detail, the manufacturing process of the display device to be set is not affected. Since the output value can be set only by measuring the input gradation, the output value that realizes multi-gradation display can be set in a short time. Therefore, it is possible to contribute to time reduction in the manufacturing process of the display device to be set, and it is possible to realize cost reduction of the display device.

  Further, by setting the display characteristic measurement result of the reference display unit to the number of gradations equal to or greater than the number of gradations of the input gradation, an output value having the number of gradations equal to or greater than the number of gradations of the input gradation is stored in a table or the like. Even if the display device does not include a color arithmetic circuit that performs high-precision arithmetic, it is possible to perform multi-gradation display using FRC technology or the like. Therefore, since the circuit scale can be reduced without reducing the display gradation, it is possible to realize a reduction in circuit scale or cost reduction and multi-gradation video display.

  Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof. FIG. 1 is a block diagram showing a configuration of an output value setting device according to the present invention. FIG. 2 is a block diagram showing a configuration of a display device that is set by the output value setting device according to the present invention. In the figure, reference numeral 1 denotes a display device, and the display device 1 displays a video on a liquid crystal display panel 2 provided therein according to a video signal input from an external device such as a PC or a playback device (not shown). . The video signal input to the display device 1 is composed of three signals of R, G, and B each having 8-bit information (input gradation) and is provided to the display processing unit 10. The display processing unit 10 includes an LUT 11, an FRC circuit 12, and a drive circuit 13 so that a given video signal is input to the LUT 11.

  The LUT 11 is a conversion table in which 10-bit output values corresponding one-to-one with 8-bit input gradations are stored in advance. Specifically, data rewriting such as EEPROM (Electrically Erasable Programmable Read Only Memory) or flash memory is performed. It is composed of possible non-volatile memory elements. The LUT 11 is composed of separate conversion tables for each of R, G, and B colors. Although a method for setting the 10-bit output value of the LUT 11 will be described later, the LUT 11 converts the input 8-bit RGB video signal into a 10-bit signal and outputs the 10-bit signal. The bit signal is supplied to the FRC circuit 12.

  The FRC circuit 12 is a circuit for performing display by the above-described FRC technology, and is for performing pseudo display with 10-bit accuracy in 4 frames based on a 10-bit RGB signal given from the LUT 11. An 8-bit signal is generated and output. The 8-bit RGB signal output from the FRC circuit 12 is supplied to the drive circuit 13. The drive circuit 13 generates an analog signal having a voltage value corresponding to the 8-bit signal supplied from the FRC circuit 12 for each color, and applies the analog signal to the display panel 2.

  The display panel 2 is a so-called liquid crystal panel having a configuration in which a liquid crystal material is sealed between a pair of glass substrates. By changing the light transmittance of the liquid crystal material according to the voltage applied by the drive circuit 13, the display panel 2 The transmission amount of the irradiated light is controlled for each pixel so that the image is displayed in gradation. The display panel 2 can perform display with an output level with an accuracy of 8 bits for each color of RGB. However, the display device 1 is configured so that the FRC circuit 12 can display an image with an accuracy of 10 bits using the display panel 2 in a pseudo manner.

  In addition, the display device 1 includes a control unit 3 that controls each unit of the display device 1 such as the drive circuit 6 that drives the display processing unit 10 and the backlight 5 described above. The control unit 3 displays each video on the display panel 2 by controlling each unit in accordance with conditions such as brightness or hue set by the user. The control unit 3 can be supplied with a control signal from an external device, and the control unit 3 controls the operation of each unit of the display device 1 in accordance with the supplied control signal. Therefore, the display device 1 can be controlled from the outside. For example, the output value stored in the LUT 11 can be rewritten by a control signal.

  The setting of the LUT 11 included in the display processing unit 10 of the display device 1 is performed using the output value setting device 30. The output value setting device 30 includes a central processing unit (CPU) 31, a random access memory (RAM) 32, a storage unit 33, a video signal output unit 34, a control signal output unit 35, a measurement result input unit 36, a sensor unit 37, and the like. I have. The output value setting device 30 outputs each 8-bit RGB video signal from the video signal output unit 34 and inputs it to the display device 1, thereby displaying the display device 1 on the display panel 2 at an arbitrary gradation. It can be made to. Further, by outputting a control signal from the control signal output unit 35 to the control unit 3 of the display device 1, the operation of the display device 1 can be controlled from the outside.

  The sensor unit 37 is attached to the display panel 2 of the display device 1 and measures characteristic values such as luminance or chromaticity of the display surface of the display panel 2. The sensor unit 37 includes a light receiving element such as a phototransistor, an A / D conversion circuit, and the like, and A / D converts a voltage output from the light receiving element in accordance with a characteristic value such as luminance or chromaticity of the display panel 2. A circuit converts the signal into a digital electric signal and outputs it. The sensor unit 37 is connected to the measurement result input unit 36 of the output value setting device 30 via a connection cable, and the measured characteristic value of the display panel 2 is given to the measurement result input unit 36. The measurement result by the sensor unit 37 is given to the measurement result input unit 36 as the tristimulus value XYZ. The measurement result input unit 36 accumulates the measurement results given from the sensor unit 37 in the storage unit 33 or the RAM 32.

  The storage unit 33 is a so-called hard disk, which stores data such as the target luminance data 33a and the reference characteristic data 33b shown in the figure, and stores various programs and data for operating the output value setting device 30 (however, In this embodiment, the target luminance data 33a is stored in the storage unit 33. However, the present invention is not limited to this, and the target luminance data 33a is calculated every time the setting process is performed. The data 33a may be configured not to be stored in advance. The CPU 31 reads out and executes the program stored in the storage unit 33, thereby controlling each unit of the output value setting device 30, various arithmetic processing, display characteristic measurement processing of the display device 1, and display device 1. Various processes such as the setting process of the LUT 11 can be performed. Further, the CPU 31 stores temporary data generated when performing various processes in the RAM 32. The RAM 32 is configured by a memory element such as SRAM (Static Random Access Memory) or DRAM (Dynamic Random Access Memory).

  The output value setting device 30 can be easily realized by connecting the sensor unit 37 to a general-purpose computer such as a PC via a cable and installing a table setting program in the storage unit 33. . However, the output value setting device 30 may be a dedicated device that performs processing for table setting of the display device 1.

For example, the output value setting device 30 can be used in the manufacturing process (inspection process, adjustment process) of the display device 1. In the manufacturing process, the display device 1 is mass-produced, and the LUT 11 can be set using the output value setting device 30 according to the following procedure for a large number of display devices 1.
(1) One display device 1 (hereinafter referred to as a reference display device) is extracted from a plurality of display devices 1.
(2) Measure the display characteristics of the reference display device.
(3) The display characteristics of the other display device 1 are measured, and the LUT 11 is set based on the display characteristics of the reference display device.

  The reference display device extracted in the above procedure (1) may be selected and extracted from a plurality of display devices 1 that are mass-produced, but the display characteristics of the plurality of display devices 1 are selected in advance. It is also possible to simply measure and to select and extract one having an average display characteristic. Further, the extraction of the reference display device may be performed automatically in the manufacturing process, or may be performed manually.

  In procedure (2), the display characteristic of the reference display device is measured using the output value setting device 30 described above. After the sensor unit 37 of the output value setting device 30 is automatically or manually attached to the reference display device extracted in the procedure (1), the output value setting device 30 starts measuring the display characteristics of the reference display device. 3 and 4 are flowcharts showing a procedure for measuring display characteristics of the reference display device by the output value setting device 30 according to the present invention. By executing a measurement program in the CPU 31 of the output value setting device 30, FIG. It is a procedure of processing to be performed. First, the output value setting device 30 stops the conversion function by the LUT 11 of the reference display device by outputting a control signal from the control signal output unit 35 to the reference display device (step S1). As a result, in the reference display device, the input RGB video signal is not converted by the LUT 11 and is further supplied to the drive circuit 13 without being subjected to display processing by the FRC technique in the FRC circuit 12. The setting device 30 can perform direct video display using the output RGB video signals on the display panel 2 of the reference display device.

  Next, the output value setting device 30 sets the gradation of each color of the RGB video signal output from the video signal output unit 34 to be equal to 0 (step S2), and matches the input gradation of each RGB color (R) = G = B), that is, so-called white solid display is performed on the display panel 2 of the reference display device, luminance is measured by the sensor unit 37 (step S3), and the tristimulus values XYZ of the measurement results are obtained. get. Next, the output value setting device 30 checks whether or not the measurement in step S3 has been completed for all gradations (step S4). If the measurement has not been completed for all the gradations (S4: NO), the output value setting device 30 increases the gradation of each color of the RGB video signal output from the video signal output unit 34 by one gradation (step S5) Returning to step S3, the sensor unit 37 measures the luminance. When the RGB video signal is an 8-bit signal for each color, the luminance measurement in step S3 is performed 256 times while increasing the gradation by 1 under the condition of R = G = B.

  When the measurement of all gradations is completed (S4: YES), the output value setting device 30 sets the gradation of one color among the RGB video signals output from the video signal output unit 34 to 255, and the other two. By setting the color gradation to 0 (for example, R = 255, G = 0, B = 0), the display panel 2 of the reference display device performs monochrome display with 255 gradations (step S6). In this state, the output value setting device 30 measures the luminance by the sensor unit 37 (step S7), and acquires the tristimulus value XYZ as the measurement result. Next, the output value setting device 30 checks whether or not the measurement in the single color display has been completed for all the RGB colors (step S8). If the measurement of all the colors has not been completed (S8: NO), The display is switched to a single color display of another color that has not been measured (step S9), and the process returns to step S7 to measure the luminance by the sensor unit 37. The measurement of luminance in step S7 is performed three times because it is performed for each color of RGB.

  Next, when the measurement of all colors is completed in step S8 (S8: YES), the luminance measurement result measured by the sensor unit 37 in steps S3 and S7 is given as the tristimulus value XYZ, so the output value setting The apparatus 30 calculates the RGB emission intensity from the tristimulus values XYZ of all the gradations of the measurement result by calculation (step S10), and further normalizes the calculated RGB emission intensity (step S11) to obtain RGB. The first emission intensity ratio is acquired. The normalization of the light emission intensity is performed by dividing the RGB light emission intensities calculated in step S10 so that the largest value is “1” and the smallest value is “0”. The output value setting device 30 performs normalization for each color of RGB.

  Next, the output value setting device 30 performs an interpolation process on the normalized RGB emission intensity, that is, the first emission intensity ratio by linear interpolation with an accuracy of 10 bits (step S12), and the measurement result obtained by linear interpolation is used as a reference. The characteristic data 33b (display characteristic of the reference display unit) is stored in the storage unit 33 (step S13), and the measurement of the reference display device is terminated. In step S12, the reference characteristic data 33b having 10-bit accuracy is obtained by linearly interpolating a value expressed for each gradation with a gamma value γ according to the following expression 1. At this time, the 10-bit output level can be expressed as Equation 2 below.

  After the measurement of the display characteristics of the reference display device by the table measuring device 30 is completed, the display characteristics of the other display devices 1 are measured as shown in the above procedure (3), and the display characteristics of the reference display device are used as the basis. Set LUT11. The setting of the LUT 11 in the procedure (3) is performed sequentially for all the mass-produced display devices 1, and the sensor unit 37 of the output value setting device 30 is automatically set to any one of the plurality of display devices 1. Or after attaching manually, the output value setting apparatus 30 starts the setting process of LUT11 of the display apparatus 1. FIG. The output value setting device 30 needs to store the target luminance data 33a in the storage unit 33 as the target display characteristics of the display device 1. The target display characteristic of the display device 1 is given as a fixed value determined based on the design stage specification of the display device 1. For example, the target brightness value in all gradations is obtained from the target gamma value in the design stage. It can be calculated. However, only the target gamma value may be stored in the storage unit 33, and the target luminance data 33a may be calculated every time the setting process is performed.

  FIG. 5 is a flowchart showing the setting procedure of the LUT 11 of the display device 1 by the output value setting device 30 according to the present invention, and shows the processing performed by the CPU 31 of the output value setting device 30 executing a setting program. It is a procedure. First, the output value setting device 30 sets the gradation of each color of the RGB video signal output from the video signal output unit 34 to be equal to the maximum gradation 255 (step S31), and the sensor unit 37 measures the luminance. (Step S32), the tristimulus value XYZ of the measurement result is acquired.

  Next, the output value setting device 30 sets the gradation of one color in the RGB video signal output from the video signal output unit 34 to 255 and sets the gradation of the other two colors to 0, thereby displaying the image. The display panel 2 of the device 1 is caused to perform monochrome display with 255 gradations (step S33). In this state, the output value setting device 30 measures the luminance by the sensor unit 37 (step S34), and acquires the tristimulus value XYZ as the measurement result. Next, the output value setting device 30 checks whether or not the measurement in the single color display is finished for all the RGB colors (step S35). If the measurement of all the colors is not finished (S35: NO), The display is switched to a single color display of another color that has not been measured (step S36), and the process returns to step S34 to measure the luminance by the sensor unit 37. The luminance measurement in step S34 is performed three times because it is performed for each color of RGB.

  Next, when the measurement of all colors is completed in step S35 (S35: YES), the measurement results in steps S32 and S34 are given as tristimulus values XYZ. From the stimulus value XYZ, the RGB emission intensity ratio (second emission intensity ratio) when the color temperature is set to 6500K is calculated (step S37). The second emission intensity ratio is different from the first emission intensity ratio calculated by normalization in step S11 of FIG. 4, and has a tendency of the measured value in step S34 and the measured value in step S35. The ratio at which the display is possible at a color temperature of 6500K. The light emission intensity when the color temperature is set to 6500K can be calculated by performing a matrix operation such as Bradford conversion based on the measurement result. The Bradford transform is to convert the tristimulus values XYZ in the device color space and the tristimulus values XYZ in the theoretical color space to each other by matrix operation, and for the calculation from the measurement results in steps S32 and S34. Can be generated. The second emission intensity ratio is a ratio of emission intensity before and after Bradford conversion, and is further converted from tristimulus values XYZ to RGB. Note that the conversion related to the color temperature is not performed by Bradford conversion, but may be performed by other conversion methods such as von Kries conversion, for example. The second light emission intensity ratio (display characteristic value for the predetermined input gradation) calculated in step S37 is a total of three values, one for each color of RGB.

  Next, the output value setting device 30 reads out the target luminance values of all the gradations from the target luminance data 33a stored in advance in the storage unit 33 (step S38), and the second emission intensity ratio calculated in step S37. The product of the target luminance value read in step S38 is calculated for each color of RGB (step S39). The product calculated here becomes the setting target display characteristic in the setting target display device 1. Next, the output value setting device 30 reads the display characteristic measurement result of the reference display device stored in the storage unit 33 as the reference characteristic data 33b (step S40).

  FIG. 6 is a schematic diagram for explaining a method for determining the output value of the LUT 11 by the output value setting device 30 according to the present invention, and the calculation result (setting target display characteristic) in step S39 of the flowchart shown in FIG. And the measurement results of the display characteristics of the reference display device read out in step S40 are shown superimposed on the same graph. Note that the target display characteristics to be set in step S39 and the display characteristics of the reference display device in step S40 exist for each color of RGB. In FIG. 6, only one color of R is shown, and the other colors G and B are shown. Are the same and are not shown. In FIG. 6, the measured display characteristics of the reference display device are indicated by a one-dot chain line, and the setting target display characteristics of the setting target display device 1 are indicated by a solid line.

  In the graph shown in FIG. 6, the horizontal axis represents the input gradation, and the vertical axis represents the output level. Regarding the display characteristics of the reference display device, the input gradation on the horizontal axis is 10-bit precision, and the output level on the vertical axis is the normalized emission intensity. The setting target display characteristics of the setting target display device 1 are such that the input gradation on the horizontal axis is 8-bit accuracy, and the output level on the vertical axis is the emission intensity ratio calculated in step S38 and in step S39. Although it is the product of the read target luminance value, it is further normalized in the same manner as the display characteristics of the reference display device.

  Since the LUT 11 of the display device 1 is a conversion table that outputs a 10-bit output value for an 8-bit input gradation, the output value setting device 30 outputs a 10-bit for each of 8-bit gradations from 0 to 255. Each value is determined. For example, when determining the 10-bit output value R for the 8-bit input gradation r, first, the target output level at the input gradation r is obtained from the setting target display characteristics (arrow (a) in FIG. 6). reference). Next, an output level approximate to the output level obtained by the arrow (a) is obtained from the display characteristics of the reference display device (see arrow (b) in FIG. 6), and a 10-bit input gradation corresponding to this output level is obtained. Obtained (see arrow (c) in FIG. 6). Thus, the 10-bit input gradation R can be determined from the 8-bit input gradation r by the procedure indicated by the arrows (a), (b), and (c).

  After the end of step S40 in the flowchart shown in FIG. 5, the output value setting device 30 performs the 10-bit output value (input gradation R) for all the 8-bit input gradations (input gradation r) according to the procedure shown in FIG. ) Is determined (step S41), and the control signal output unit 35 outputs a control signal to the display device 1, thereby storing the determined 10-bit output value in the LUT 11 in association with the 8-bit input gradation ( Step S42), the setting process of the LUT 11 is terminated.

  After the setting of the LUT 11 by the output value setting device 30 for the display device 1 to be set is completed, the sensor unit 37 of the output value setting device 30 is automatically or manually removed from the display device 1 and attached to another display device 1. The LUT 11 is set sequentially. The display characteristics of the reference display device need only be measured once at the beginning, but each time the LUT 11 of the predetermined number of other display devices 1 is set, the display characteristics of the reference display device are measured and the output value setting device 30 is set. The reference characteristic data 33b stored in the storage unit 33 may be updated.

  In the output value setting device 30 configured as described above, one reference display device is extracted from a plurality of mass-produced display devices 1, and display characteristics at all input gradations are measured in advance. For the display device 1 for which the LUT 11 is to be set, the output value of the LUT 11 can be determined by performing simple measurement of only the maximum input gradation, so that the LUT 11 can be set in a short time in the manufacturing process of the display device 1. Can be done. Further, since the output value setting device 30 can acquire the display characteristics of the reference display device with an accuracy of 10 bits by interpolation processing, an output value with an accuracy of 10 bits can be set in the LUT 11 of the display device 1. The display device 1 can perform high-quality video display using FRC technology. Therefore, since the display device 1 can perform high-quality video display without including the color arithmetic circuit 101 shown in FIG. 8, the circuit scale of the display device 1 can be reduced. Thus, by setting the LUT 11 of the display device 1 using the output value setting device 30, high-quality video display by the display device 1 can be realized, and the cost of the display device 1 can be reduced.

  In the present embodiment, the output value setting device 30 is configured by a single device, but is not limited to this, and may be configured by a plurality of devices. For example, the device for measuring the display characteristics of the reference display device and the device for setting the LUT 11 of the display device 1 to be set may be different devices. In this case, the measurement was performed with one device. What is necessary is just to give the display characteristic of a reference | standard display apparatus to another apparatus via a network or a recording medium. Further, the display device 1 itself may be configured to have a function of measuring display characteristics as a reference display device and a function of setting the LUT 11 as a display device to be set. In addition, the display device 1 illustrated in FIG. 2 has a configuration in which the color arithmetic circuit 101 in FIG. 8 is not mounted, but the display device 1 may be configured to include a color arithmetic circuit. The characteristics shown in FIG. 6 are merely examples, and the present invention is not limited to this.

(Modification)
The configuration shown in FIG. 1 and FIG. 2 is a configuration for setting the LUT 11 of the display device 1 using the output value setting device 30, but a configuration for mounting a function for setting the output value of the LUT 11 on the display device may be possible. This configuration is shown in the following modification. FIG. 7 is a block diagram showing a configuration of a display device 201 according to a modification of the present invention. The display device 201 according to the modification includes a sensor unit 237 that measures a characteristic value such as luminance or chromaticity of the display surface of the display panel 2, and gives a measurement result to the control unit 203. In addition, the display device 201 according to the modification includes a card slot 220 in which a memory card 250 is inserted. The card slot 220 reads data from the inserted memory card 250 and supplies the data to the control unit 203, and also includes a control unit. The data given from 203 can be written in the memory card 250.

  In the display device 201 according to the modified example, the target luminance data 33a and the reference characteristic data 33b stored in advance in the memory card 250 are acquired by reading out the card slot 220, and the same procedure as that shown in the flowchart of FIG. The control unit 203 performs processing to set the output value of the LUT 11. Note that the display characteristics of the reference display device are measured in advance using another device (for example, the output value setting device 30 shown in FIG. 1).

  As described above, since the display device 201 has a function of setting the LUT 11, a plurality of mass-produced display devices 201 can simultaneously set the LUT 11. The time required for the manufacturing process can be further shortened. In FIG. 7, the control unit 203 acquires the target luminance data 33a and the reference characteristic data 33b via the memory card 250 and the card slot 220. However, the present invention is not limited to this, and other storage media may be used. The target luminance data 33a and the reference characteristic data 33b may be acquired via the network. When the display device has a communication function, the target luminance data 33a and the reference characteristic data 33b are acquired via the network. Also good. Further, the communication function of the display device may be used to store data in advance in a storage unit such as a flash memory or a hard disk built in the display device.

  Further, the sensor unit 37 of the output value setting device 30 shown in FIG. 1 and the sensor unit 237 of the display device 201 shown in FIG. 7 are directly attached to the display panel 2 to perform measurement. For example, a measurement device such as a CCD camera may be set apart from the display panel 2 and the display characteristics of the display panel 2 may be measured by the measurement device.

It is a block diagram which shows the structure of the output value setting apparatus which concerns on this invention. It is a block diagram which shows the structure of the display apparatus with which setting is performed by the output value setting apparatus which concerns on this invention. It is a flowchart which shows the measurement procedure of the display characteristic of the reference | standard display apparatus by the output value setting apparatus which concerns on this invention. It is a flowchart which shows the measurement procedure of the display characteristic of the reference | standard display apparatus by the output value setting apparatus which concerns on this invention. It is a flowchart which shows the setting procedure of LUT of the display apparatus by the output value setting apparatus which concerns on this invention. It is a schematic diagram for demonstrating the determination method of the output value of LUT by the output value setting apparatus which concerns on this invention. It is a block diagram which shows the structure of the display apparatus which concerns on the modification of this invention. It is a schematic diagram which shows the structure of the conventional display apparatus carrying FRC technique. It is a schematic diagram for demonstrating the fall of the display gradation by the fall of the processing precision of a color arithmetic circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Display apparatus 2 Display panel (display part)
3 Control Unit 5 Backlight 6 Drive Circuit 10 Display Processing Unit 11 LUT (Storage Unit, Table)
12 FRC circuit 13 Drive circuit 30 Output value setting device 31 CPU
33 storage unit 33a target luminance data (predetermined target display characteristics)
33b Reference characteristic data (display characteristic of reference display)
34 Video signal output unit 35 Control signal output unit 36 Measurement result input unit 37 Sensor unit 201 Display device 203 Control unit 220 Card slot 237 Sensor unit 250 Memory card

Claims (8)

In an output value setting method for setting an output value related to driving of a display unit for an input gradation given for each of a plurality of colors,
When the input display is changed to the input gradation that makes the monochrome display of each color, as well as the characteristics of changes in brightness and chromaticity when the input gradation is changed by aligning all colors on the reference display section that is the standard for setting Measure the luminance and chromaticity characteristics as display characteristics,
In the display unit to be set, the luminance and chromaticity of the display unit with respect to a predetermined input gradation in which all colors are aligned and a predetermined input gradation that is a single color display of each color are measured as display characteristic values,
Based on the luminance and chromaticity measured as the display characteristic value, a light emission intensity that enables display at a predetermined color temperature on the display unit to be set is calculated,
Calculate the ratio for each color of the calculated emission intensity and the emission intensity according to the luminance and chromaticity measured as the display characteristic value,
The luminance is adjusted according to the ratio with respect to the correspondence between the input gradation and luminance for each color corresponding to a predetermined gamma value, and the correspondence between the input gradation and the adjusted luminance is displayed on the display unit to be set The target display characteristics for setting the input gradation and brightness for each color in
Based on the setting target display characteristic and the measured display characteristic of the reference display unit, an output value related to the driving of the setting target display unit is determined,
An output value setting method characterized by storing the determined output value in association with the input gradation. Based on the luminance and chromaticity measured as the display characteristics of the reference display unit, to calculate the emission intensity for all gradations for each color,
The output value is determined by acquiring the luminance corresponding to one input gradation from the setting target display characteristic and setting the emission intensity approximate to the luminance acquired from the setting target target display characteristic to the display characteristic of the reference display unit. The process of acquiring the input gradation corresponding to the acquired emission intensity from the display characteristics of the reference display unit and determining the acquired input gradation as an output value is performed for all gradations. The output value setting method according to claim 1. Increasing the emission intensity calculated based on the display characteristics of the reference display unit to a number of gradations equal to or greater than the number of gradations of the input gradation by interpolation processing,
The output value setting method according to claim 2 , wherein the determination of the output value is performed based on the calculated setting target display characteristic and the result of the interpolation process. A table for outputting an output value associated with the given input tone, the output according to any one of claims 1 to 3, characterized in that for storing the output value of the determined Value setting method. The display characteristic when the input gradation is changed by aligning all the colors of the reference display unit is measured by changing the input gradation over all gradations that can be input. The output value setting method according to any one of claims 1 to 4 . The display characteristic value of the display unit to be set is measured by measuring luminance and chromaticity of the display unit with respect to a maximum input gradation. Output value setting method. Output value setting for setting an output value in the storage unit for a display device including a display unit and a storage unit that stores an output value related to driving of the display unit with respect to an input gradation given for each of a plurality of colors In the device
In the reference display section of the display device that is the reference for setting, the characteristics of changes in luminance and chromaticity when changing the input gradation by aligning all colors, and the input gradation that changes to a single color display for each color Means for measuring luminance and chromaticity characteristics as display characteristics when
Means for measuring the luminance and chromaticity of the display unit as a display characteristic value with respect to a predetermined input gradation in which all colors are aligned and a predetermined input gradation that is a single color display of each color in the display unit of the display device to be set;
Means for calculating a light emission intensity enabling display at a predetermined color temperature on the display unit of the display device to be set based on the luminance and chromaticity measured as the display characteristic value;
Means for calculating a ratio for each color between the calculated emission intensity and the emission intensity according to the luminance and chromaticity measured as the display characteristic value;
To the corresponding relation between the input gradation and brightness of each color corresponding to the predetermined gamma value, the luminance is adjusted according to the ratio, the input gradation and adjusted luminance correspondence the setting target of the display device Means for setting the target display characteristics of the input gradation and luminance for each color in the display unit;
Based on the display characteristics of the reference display section that the set target target display characteristics and measurements, and means for determining an output value according to the driving of the display unit of the setting target of the display device,
The output value setting apparatus characterized in that the determined output value is stored in the storage unit in association with the input gradation. In a display device comprising: a display unit; and a storage unit that stores an output value related to driving of the display unit with respect to an input gradation given for each of a plurality of colors.
Characteristics of changes in luminance and chromaticity when the input gradation is changed by aligning all colors in the reference display section of another display device that is the reference for setting, and the input gradation that is a single color display of each color Means for obtaining as a display characteristic what measured the characteristics of luminance and chromaticity when changed to
Means for measuring the luminance and chromaticity of the display unit as a display characteristic value with respect to a predetermined input gradation in which all colors are aligned and a predetermined input gradation that is a single color display of each color;
Means for calculating a light emission intensity that enables display at a predetermined color temperature on the display unit based on the luminance and chromaticity measured as the display characteristic value;
Means for calculating a ratio for each color between the calculated emission intensity and the emission intensity according to the luminance and chromaticity measured as the display characteristic value;
The luminance is adjusted according to the ratio with respect to the correspondence between the input gradation and the luminance for each color corresponding to a predetermined gamma value, and the correspondence between the input gradation and the adjusted luminance for each color in the display unit. Means for setting target display characteristics for input gradation and brightness of
Means for determining an output value related to driving of the display unit based on the target display characteristics to be set and the acquired display characteristics of the other display device;
The determined output value is stored in the storage unit in association with an input gradation.

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