JP5309081B2 - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high luminance display capable of correcting color drift in each area of a screen due to the effect of external light, etc. <P>SOLUTION: When the spectral radiance of a backlight is less than the spectral radiance of external light at the time of factory shipment, a CPU 30 generates, for each area, a correction matrix for color correction so that color production by external light, or color production by reflected light on a half mirror 12 matches color production only by irradiation light from the backlight, and sends the generated correction matrix for each area as parameter information to a video signal processor 33 to make the video signal processor 33 perform color correction for each area on the basis of the parameter information. The CPU 30 generates the correction matrix on the basis of the spectral radiance of external light detected by each second spectral radiance sensor 18 provided for each area, the spectral radiance of the backlight detected at the time of the factory shipment, and the spectral transmittance and color-matching functions of color filters. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a display device capable of performing color correction according to the brightness of external light.

  For example, when the display device is used for outdoor digital signage, that is, an electronic signboard, the luminance of external light exceeds the luminance of the display device, and there is a problem that visibility is impaired. Further, when the luminance of the display device is increased in order to prevent the influence of external light, there is a problem that power consumption and cost are increased. In order to improve these problems, transflective liquid crystal display devices have been proposed.

  The transflective liquid crystal display device is a hybrid type liquid crystal display device including a transmissive liquid crystal display device such as a backlight type and a reflective liquid crystal display device. The transflective liquid crystal display device performs mode switching so that the color is generated by reflection of external light such as sunlight during the daytime, and the color is generated by the transmission of the backlight during the cloudy day or at night.

  Video contents such as still images and moving images are usually created assuming a transmissive liquid crystal display device. Therefore, a transflective liquid crystal display device or a reflective liquid crystal display device having a half mirror is affected by external light, and its color gamut and white balance fluctuate, so that the video content is different from the color intended by the content creator. May be displayed.

  FIG. 15 is a diagram illustrating the xy chromaticity 61 when a color shift occurs due to the influence of external light. The xy chromaticity 61 is the xy chromaticity of the XYZ color system defined by CIE (Commission Internationale de I'Eclairage), the vertical axis is the y chromaticity of the xy chromaticity, and the horizontal axis is the xy chromaticity. x chromaticity. A color gamut 605 is a color gamut of a color matching function according to CIE1931. A color gamut 611 is a color gamut when color is generated by external light, and a color gamut 602 is a color gamut when color is generated by a backlight. The color gamut 611 is deviated from the color gamut 602, indicating that color misregistration has occurred. Further, the white point 613 in the external light is shifted from the white point 604 in the backlight. That is, the color development differs between when the backlight is transmitted and when external light is reflected.

In a transflective liquid crystal display device using a half mirror, it is known that the reflectance of external light is, for example, about several (%) with respect to tens of thousands (cd / m ² ) of external light luminance. . This is a process of reflecting external light with a half mirror, and it is necessary to pass through the front protective glass, polarizing plate, liquid crystal display (hereinafter “LCD”) panel, color filter, etc. Is caused by the attenuation. That is, a transflective liquid crystal display device using a half mirror has a low luminance generation efficiency because it has a low external light reflectance.

  In addition, in a display device installed outdoors, when the screen is enlarged, for example, when the screen size exceeds 100 inches, the light from outside light hits a part of the screen and becomes brighter than other areas. is there. That is, when the external light conditions are different for each region of the screen, the luminance and chromaticity may be different for each region.

  As a first conventional technique, there is an environment adaptive image display system described in Patent Document 1. This environment-adaptive image display system corrects the input / output profile of the projector based on the color light information of the image display area measured by the color light sensor. Specifically, a coordinate value to be a complementary color pair is calculated from the coordinate value in the color space in the reference environment obtained based on the color light information in the preprocessing and the coordinate value in the actual visual environment, and this complementary color pair is calculated. The input / output profile is corrected from the coordinate value. The coordinate value to be a complementary color pair can be obtained by obtaining an inverse vector of the binding vector indicating the coordinate position of the coordinate value of the white value in the actual presentation environment in the color space.

  As a second conventional technique, there is an image observation apparatus described in Patent Document 2. This image observation apparatus can switch between a reflection type and a transmission type. When the reflection type is selected, color correction of the display image is performed based on the external light information such as the color temperature of the external light acquired by the external sensor and the information added to the image data to be displayed.

  As a third conventional technique, there is a portable data processing device described in Patent Document 3. This portable data processing apparatus uses a transflective liquid crystal display device, and the back of the transflective liquid crystal display device is determined according to the measurement result of a sensor that measures the amount of external light incident on the transflective liquid crystal display device. The luminance of the liquid crystal illumination unit that displays data on the liquid crystal display unit is controlled by irradiating light.

  As a fourth conventional technique, there is a liquid crystal display control device described in Patent Document 4. The liquid crystal display control device adjusts the backlight luminance based on the illuminance data from the illumination detection unit that detects the amount of external light emitted from the outside to the liquid crystal display unit, the illuminance data from the illumination detection unit, and The contrast is adjusted based on temperature data from a temperature detection unit that detects the temperature of the liquid crystal display unit.

  As a fifth conventional technique, there is a display device described in Patent Document 5. This display device is a transflective liquid crystal display device that controls the light emission intensity of the illumination means of the display panel according to the output of the photosensor provided at the periphery of the display region. Has spectral sensitivity adjusting means for matching the visual sensitivity characteristics of a person.

JP 2001-320725 A JP 2003-209855 A Japanese Patent Laid-Open No. 6-18880 Japanese Patent Laid-Open No. 9-311317 JP 2007-212890 A

  The first conventional technique is used for a projector, and is not used for a transflective or transmissive liquid crystal display device. In addition, none of the second to fourth conventional techniques uses the spectral characteristics of external light. The fifth conventional technique adjusts the spectral sensitivity of the optical sensor, and does not improve the visibility using the spectral characteristics of external light. In addition, none of the conventional techniques solves the problem of correcting a color shift that varies from region to region.

  An object of the present invention is to provide a high brightness display device capable of correcting a color shift for each region of a screen due to the influence of external light or the like.

The present invention provides an irradiation light emitted by a backlight unit provided on a back side of a display screen of a display unit that displays image information on a display screen divided into a plurality of areas, and the display unit and the backlight unit. Reflected light from a half mirror provided in between, acquired external light acquired by a plurality of external light acquiring means provided at the peripheral edge of the display means, or reflected light or acquired external light to the display means A display device that develops the color of image information by transmitting through a provided color filter,
A first spectral characteristic detecting means for detecting a spectral characteristic represented by a predetermined wavelength interval in a predetermined wavelength range for the irradiation light;
Provided in correspondence to each of the plurality of regions on the periphery of the display screen of the display unit, the external light irradiated from the outside to the display means, the spectral characteristics represented by wavelength interval predetermined in the wavelength range of predetermined A plurality of second spectral characteristic detecting means for detecting;
Color correction means for performing color correction of image information to be displayed on the display means, and supplying the image information on which color correction has been performed to the display means;
Wherein to detect a spectral characteristic of the illumination light to the first spectral characteristic detecting means, and to detect the spectral characteristics of external light to the plurality of second spectral characteristic detecting unit, detecting the first spectral characteristic detecting means Based on the spectral characteristics of the irradiated light and the spectral characteristics of the external light detected by the plurality of second spectral characteristics detecting means, color correction information for each region is generated, and the generated color correction information is converted into the color Control means for supplying to the correction means, and causing the color correction means to perform color correction of image information to be displayed for each region based on the supplied color correction information ,
The control means includes
The luminance value obtained from the spectral characteristic of the external light detected by at least one second spectral characteristic detection unit among the plurality of second spectral characteristic detection units is detected by the first spectral characteristic detection unit. When it is less than the luminance value obtained from the spectral characteristics of the irradiation light, the backlight means is irradiated with the irradiation light,
A backlight spectral luminance matrix representing a luminance value for each wavelength with respect to a predetermined range of wavelengths of the irradiation light is L1, and an external light spectral luminance matrix representing a luminance value for each wavelength with respect to the predetermined range of wavelengths of the external light. L2, where C is a spectral transmittance matrix of a color filter representing spectral transmittance for each wavelength with respect to a predetermined range of wavelengths, and S is a color matching function matrix representing luminance values for each wavelength with respect to a predetermined range of wavelengths. The correction matrix A is calculated by the following formula,
A = {(S ^t · (L1 + L2) × C) ^t } ⁻¹ · (S ^t · L1 × C) ^t
(In the above equation, “t” is a transposed matrix, “+” is an addition of matrices, and “−1” is an operation symbol representing an inverse matrix.)
The correction matrix A calculated for each region is supplied to the color correction unit as the color correction information,
The color correction unit corrects a color signal representing image information for each region based on the correction matrix A, and transmits the irradiation light and the reflected light or the acquired external light to the color filter. The display device is characterized in that the color of the image information that is colored is matched with the color of the image information that is colored by transmitting only the irradiation light through the color filter .

Further, according to the present invention, the control means is provided for each of the areas.
The spectral characteristics of external light irradiated from the outside to the display means, is detected in the second spectral characteristic detecting means for each first time interval predetermined,
A luminance value obtained from the spectral characteristics of the external light at the first time the predetermined luminance obtained from the spectral characteristics of the external light at the second time from said first time first time interval has elapsed When the difference from the value is greater than or equal to a predetermined first threshold, the color correction information is newly generated based on the spectral characteristics of the external light at the second time .

In the present invention, the control means includes
The spectral characteristic of the light emitted from the backlight unit is detected by the first spectral characteristic detection unit every time a predetermined period of time elapses from a predetermined time point and the predetermined time point,
The difference between the luminance value obtained from the spectral characteristic at the predetermined time point and the luminance value obtained from the spectral characteristic detected every time the predetermined period elapses from the predetermined time point is equal to or greater than a predetermined second threshold value. The difference in luminance value is equal to or greater than the second threshold based on the spectral characteristic at the predetermined time point and the spectral characteristic when the difference in luminance value is equal to or greater than the second threshold. the color of the image information to be colored by irradiation light when the generating the color correction information to match the color of the image information to be developed by the irradiation light at the time the predetermined, the generated the color correction information, the color The correction means is supplied.

The present invention, said control means, said at wavelength intervals predetermined for the wavelength range predetermined calculates a difference between the respective luminance values obtained from the two spectral characteristics, the calculated average of the sum of the difference, The difference between the luminance values is used.

    Further, the invention is characterized in that the spectral characteristic is a luminance characteristic expressed for each wavelength in the visible light region.

The present invention further includes a diffusing plate for diffusing the irradiation light and the acquired external light,
The first spectral characteristic detection unit and the plurality of second spectral characteristic detection units detect spectral characteristics of light diffused by a diffusion plate.

  The present invention is further characterized in that it further includes an optical fiber for guiding a part of the irradiation light emitted from the backlight means to the first spectral characteristic detection means.

  In the invention, it is preferable that the optical fiber guides external light acquired by the plurality of external light acquisition means to the second spectral characteristic detection means.

  In addition, the present invention is a transflective liquid crystal display device including the display unit, the backlight unit, and the half mirror.

Further, the present invention is a transmissive liquid crystal display device including the display means, the backlight means and the external light acquisition means,
The external light acquisition means is an opening for acquiring external light provided at a peripheral portion of the backlight means,
The backlight means includes a light guide plate portion that guides external light,
The plurality of second spectral characteristic detection means are respectively disposed in proximity to the outside light acquisition means.

According to the present invention, the irradiation light emitted by the backlight means provided on the back side of the display screen of the display means for displaying the image information on the display screen divided into a plurality of areas, the display means and the backlight means The reflected light from the half mirror provided between the external light and the acquired external light acquired by the external light acquiring means provided at the periphery of the display means, or the reflected light or the acquired external light to the display means In developing the color of the image information by transmitting the provided color filter, the first spectral characteristic detecting means detects the spectral characteristic represented by a predetermined wavelength interval in a predetermined wavelength range for the irradiation light. The plurality of second spectral characteristic detection means are provided in correspondence with each of the plurality of regions on the peripheral edge of the display screen of the display means, and the wavelength determined in advance with respect to the external light irradiated on the display means from the outside Spectral characteristics represented by a predetermined wavelength interval in the range are detected. The color correction means performs color correction of image information to be displayed on the display means, and supplies the image information on which color correction has been performed to the display means for display. The control unit causes the first spectral characteristic detection unit to detect the spectral characteristic of the irradiation light , causes the plurality of second spectral characteristic detection units to detect the spectral characteristic of external light , and Based on the spectral characteristics of the irradiation light detected by the spectral characteristics detecting means and the spectral characteristics of the external light detected by the plurality of second spectral characteristics detecting means, color correction information for each region is generated and generated Color correction information is supplied to the color correction unit, and based on the supplied color correction information, the color correction unit performs color correction of image information to be displayed for each region.
Specifically, the control means is
A backlight spectral luminance matrix representing a luminance value for each wavelength with respect to a predetermined range of wavelengths of the irradiation light is L1, and an external light spectral luminance matrix representing a luminance value for each wavelength with respect to the predetermined range of wavelengths of the external light. L2, where C is a spectral transmittance matrix of a color filter representing spectral transmittance for each wavelength with respect to a predetermined range of wavelengths, and S is a color matching function matrix representing luminance values for each wavelength with respect to a predetermined range of wavelengths. The correction matrix A is calculated by the following formula,
A = {(S ^t · (L1 + L2) × C) ^t } ⁻¹ · (S ^t · L1 × C) ^t
(In the above equation, “t” is a transposed matrix, “+” is an addition of matrices, and “−1” is an operation symbol representing an inverse matrix.)
The correction matrix A calculated for each region is supplied to the color correction unit as the color correction information,
The color correction unit corrects a color signal representing image information for each region based on the correction matrix A, and transmits the irradiation light and the reflected light or the acquired external light to the color filter. The color of the image information that is colored is matched with the color of the image information that is colored by transmitting only the irradiation light through the color filter .

As described above, according to the present invention, the control unit is configured to detect the spectral characteristics of the irradiation light detected by the first spectral characteristic detection unit and the spectrum of the external light detected by the plurality of second spectral characteristic detection units. Based on the characteristics, the spectral transmittance of the color filter provided in the display means, and the color matching function, a correction matrix A for color correction is calculated, and the calculated correction matrix A is used as color correction information. Therefore, since the correction matrix A, which is color correction information that can correct color misregistration accurately, can be calculated , color misregistration for each area of the screen due to the influence of external light or the like can be corrected. In particular, in a digital signage using a display device, for example, a transflective liquid crystal display device or a transmissive liquid crystal display device capable of increasing the brightness with external light, the first spectral characteristic detecting means, for example, the first spectral device. The spectral characteristic of the irradiation light from the backlight is detected by the radiance sensor 16, and the spectral characteristic of the external light is detected and detected by a plurality of second spectral characteristic detection means, for example, the second spectral radiance sensor 18. By performing color correction for each area based on the spectral characteristics, it is possible to prevent the deterioration of visibility due to the influence of external light or the change of backlight over time, and the backlight in a transflective liquid crystal display device or a transmissive liquid crystal display device. The problem of color shift and insufficient brightness in the illumination mode, the external light mode, and the backlight illumination and the external light mode can be improved.

In addition, in both outdoor installations affected by external light and indoor installations that depend on backlight illumination, there is no color shift even if the same image is displayed. The display device can be used both outdoors and indoors without giving a sense of incongruity.
In addition, the control means has a luminance value obtained from the spectral characteristic of the external light detected by at least one second spectral characteristic detection means among the plurality of second spectral characteristic detection means. When the luminance value is less than the luminance value obtained from the spectral characteristic of the irradiation light detected by the spectral characteristic detection means, the backlight means is irradiated with the irradiation light. Then, the correction matrix A calculated for each region corrects a color signal representing image information, and an image that develops color when transmitting the irradiation light and the reflected light or the extra-acquisition light to the color filter. The color of information is color correction information for matching the color of image information that is colored by transmitting only the irradiation light through the color filter. Therefore, when the luminance of the external light is insufficient, the luminance can be supplemented by the light irradiated by the backlight, and the color of the image information can be developed by the light that combines the light irradiated by the backlight and the external light, It is possible to obtain a color display equivalent to that when only irradiation light from the backlight is used.

According to the present invention, the control means, for each of the regions, the spectral characteristics of external light irradiated from the outside to the display means, previously determined first of said every time interval the second spectral characteristic detecting means To detect. Then, determined from the spectral characteristics of the external light at the second time and the brightness values obtained from the spectral characteristics of the external light, which is the first time interval from the first time has elapsed in the first time the predetermined When the difference from the luminance value to be obtained is equal to or greater than a predetermined first threshold, the color correction information is newly generated based on the spectral characteristics of the external light at the second time . Accordingly, when the degree of color shift of the display color due to the performance degradation due to the time change of the external light is small, the calculation process for performing the color correction can be omitted, so that the screen display is not delayed.

Further, according to the present invention, the control means determines the spectral characteristics of the light emitted from the backlight means at a predetermined time point and every time a predetermined period elapses from the predetermined time point, the first spectral characteristic detection means. To detect. The difference between the luminance value obtained from the spectral characteristic at the predetermined time point and the luminance value obtained from the spectral characteristic detected each time the predetermined period elapses from the predetermined time point is equal to or greater than a predetermined second threshold value. The difference in luminance value is greater than or equal to the second threshold based on the spectral characteristic at the predetermined time point and the spectral characteristic when the difference in luminance value is greater than or equal to the second threshold. the color of the image information to be developed by the irradiation light when it is configured to generate the color correction information to match the color of the image information to be developed by the irradiation light at the time the predetermined, the generated color correction information, the Supply to color correction means.

  Therefore, even if the illumination light from the backlight used in the display device changes due to aging, color misregistration due to deterioration of the backlight performance is suppressed by performing color correction for the aging, and display is performed. It is possible to maintain the same color display as that when the device was shipped from the factory.

According to the present invention, the control means, wherein the wavelength interval predetermined for the wavelength range predetermined calculates a difference between the respective luminance values obtained from the two spectral characteristics, the average of the sum of the calculated the difference Is the difference between the luminance values . Therefore, even if the luminance changes depending on the wavelength, the difference between the luminance values can be obtained from the two spectral characteristics.

  Further, according to the present invention, the spectral characteristic is a luminance characteristic expressed for each wavelength in the visible light region (380 to 780 (nm)), and therefore can be corrected for each wavelength, and color misregistration can be more accurately performed. It can be corrected.

Further, according to the present invention, further comprising a diffusing plate that diffuses the irradiation light and the acquisition outside light,
The first spectral characteristic detecting means and the plurality of second spectral characteristic detecting means detect spectral characteristics of the light diffused by the diffusion plate, so that appropriate luminance can be obtained even if the luminance is locally high or low. Can be detected.

  Further, according to the present invention, the optical system further includes an optical fiber that guides a part of the irradiation light emitted from the backlight unit to the first spectral characteristic detecting unit, so that the first spectral characteristic detecting unit may be provided separately. , Light attenuation can be suppressed.

  Further, according to the present invention, the optical fiber guides the external light acquired by the plurality of external light acquisition means to the second spectral characteristic detection means, so that attenuation of light can be suppressed even for external light. .

  According to the invention, the display device is a transflective liquid crystal display device including the display means, the backlight means, and the half mirror. Accordingly, it can be realized as a transflective liquid crystal display device by the light irradiated by the backlight means and the reflected external light, and it is possible to prevent the visibility from being deteriorated by the external light and to suppress the color shift and the luminance change due to the external light. .

  According to the invention, the display device is a transmissive liquid crystal display device including the display means, the backlight means, and the external light acquisition means. The external light acquisition means is an opening for acquiring external light provided at a peripheral portion of the backlight means, and the backlight means includes a light guide plate portion that guides external light. The plurality of second spectral characteristic detection means are arranged in proximity to each of the external light acquisition means. Accordingly, the transmission type liquid crystal display device 2 is realized by the irradiation light from the backlight 22 and the acquired external light by the plurality of openings and the light guide plate, and the visibility is not deteriorated by the external light. And a change in luminance can be suppressed.

1 is a side view schematically showing an appearance of a transflective liquid crystal display device 1 according to a first embodiment of the present invention. It is a front view which shows typically the external appearance of the transflective liquid crystal display devices 1 and 1a. 1 is a block diagram illustrating a configuration of a transflective liquid crystal display device 1. FIG. It is the graph 51 which shows an example of the light source spectral luminance of external light and a backlight. It is a graph 52 which shows an example of the spectral transmittance of the color filter of the LCD module. It is a graph 53 which shows an example of the spectral characteristic of the irradiation light of the backlight 13 at the time of color filter transmission. It is a graph 54 which shows an example of the spectral characteristic of external light at the time of color filter transmission. It is a graph 55 which shows the visibility characteristic of a color matching function. It is a figure for demonstrating the evaluation method for detecting the change of external light. It is a flowchart which shows the process sequence of the 1st color correction process which turns off the backlight 13 and performs color correction. It is a flowchart which shows the process sequence of the 2nd color correction process which performs color correction using the backlight 13 together. An xy chromaticity 60 when color correction is performed in the transflective liquid crystal display device 1 is shown. It is a side view which shows typically the external appearance of the transmissive liquid crystal display device 2 which is the 2nd Embodiment of this invention. It is a front view which shows typically the external appearance of the transmissive liquid crystal display devices 2 and 2a. It is a figure which shows xy chromaticity 61 when the color shift by the influence of external light generate | occur | produces.

  FIG. 1 is a side view schematically showing the appearance of a transflective liquid crystal display device 1 according to the first embodiment of the present invention. FIG. 2 is a front view schematically showing the appearance of the transflective liquid crystal display devices 1 and 1a. FIG. 1A shows an external view of the transflective liquid crystal display device 1 as viewed from the side. A transflective liquid crystal display device 1 as a display device includes a liquid crystal display (LCD) module 11, a half mirror 12, a backlight 13, diffusing plates 14 and 17, an optical fiber 15, and a first spectral radiance sensor. 16 and the second spectral radiance sensor 18.

  The LCD module 11 serving as a display means is constituted by a liquid crystal panel, for example, and displays image information. The LCD module 11 has a color filter (not shown), and colors the color of image information to be displayed by transmitting light from behind through the color filter. The half mirror 12 is arranged behind the LCD module 11, that is, on the back side of the display screen of the LCD module 11. The half mirror 12 reflects external light such as sunlight or illumination light transmitted through the LCD module 11 and transmits the reflected light from the back of the LCD module 11 toward the display screen, that is, the front surface.

  The backlight 13 serving as the backlight means is disposed behind the half mirror 12. That is, the LCD module 11, the half mirror 12, and the backlight 13 are arranged in this order from the front side of the LCD module 11. The backlight 13 has a light source (not shown), irradiates the irradiation light emitted from the light source in the direction of the half mirror 12, and transmits the irradiation light from the back of the half mirror 12 toward the front surface of the LCD module 11.

  The diffusion plate 14 is provided on the lower side of the backlight 13 in the screen direction of the LCD module 11, and supplies the optical fiber 15 by diffusing and transmitting the irradiation light emitted from the light source of the backlight 13. The optical fiber 15 guides the irradiation light supplied from the diffusion plate 14 to the first spectral radiance sensor 16 and supplies it to the first spectral radiance sensor 16.

  The first spectral radiance sensor 16 is a detection device that detects the spectral characteristics of the irradiation light supplied from the optical fiber 15, that is, the irradiation light of the backlight 13. The spectral characteristic which is a spectrum is a characteristic which expresses the light quantity of light, that is, the luminance by a predetermined wavelength interval in a predetermined wavelength range. The predetermined wavelength range is, for example, a wavelength range of 380 nm to 780 nm, and the predetermined wavelength interval is, for example, a wavelength interval of 1 nm.

  The diffusion plate 17 supplies the second spectral radiance sensor 18 by diffusing and transmitting the external light applied to the diffusion plate 17 from the front side of the LCD module 11. The second spectral radiance sensor 18 is a detection device that is provided adjacent to the back of the diffusion plate 17 and detects the spectral characteristics of external light supplied from the diffusion plate 17. Four diffuser plates 17 and second spectral radiance sensors 18 are provided at the peripheral edge of the screen of the LCD module 11. The diffusing plates 14 and 17 are provided for the purpose of preventing damage due to direct light incidence and preventing reduction in measurement accuracy due to various imaging with respect to the first spectral radiance sensor 16 and the second spectral radiance sensor 18. It is not necessarily limited to this configuration.

  FIG. 2A is a front view schematically showing the appearance of the transflective liquid crystal display device 1, and FIG. 2B is a transflective liquid crystal display which is a modification of the transflective liquid crystal display device 1. It is a front view which shows typically the external appearance of the apparatus 1a. 2A and 2B show the arrangement of the four second spectral radiance sensors 18, and the diffusion plates provided adjacent to the second spectral radiance sensors 18 are not shown. Omitted. The second spectral radiance sensor 18 is a general term for the second spectral radiance sensors 18a to 18d shown in FIG. 2A or the second spectral radiance sensors 18e to 18h shown in FIG.

  In the transflective liquid crystal display device 1 shown in FIG. 2A, the second spectral radiance sensors 18 a to 18 d are arranged one by one at the corners of the peripheral portion of the screen of the LCD module 11. The display screen of the LCD module 11 shown in FIG. 2A is divided into four regions R1a to R1d by a straight line orthogonal to the center of the long side in the horizontal direction and a straight line orthogonal to the center of the short side in the vertical direction. ing. The second spectral radiance sensor 18a is a spectral radiance sensor for performing color correction of the region R1a, and the second spectral radiance sensor 18b is a spectral radiance sensor for performing color correction of the region R1b, The second spectral radiance sensor 18c is a spectral radiance sensor for performing color correction of the region R1c, and the second spectral radiance sensor 18d is a spectral radiance sensor for performing color correction of the region R1d.

  In the transflective liquid crystal display device 1a shown in FIG. 2 (b), the second spectral radiance sensors 18e to 18h are provided in the central part in the long side direction and the central part in the short side direction of the peripheral part of the screen of the LCD module 11. One is arranged in each. The display screen of the LCD module 11 shown in FIG. 2B is divided into four regions R1e to R1h by two diagonal lines. The second spectral radiance sensor 18e is a spectral radiance sensor for performing color correction of the region R1e, the second spectral radiance sensor 18f is a spectral radiance sensor for performing color correction of the region R1f, The second spectral radiance sensor 18g is a spectral radiance sensor for performing color correction of the region R1g, and the second spectral radiance sensor 18h is a spectral radiance sensor for performing color correction of the region R1h.

  Hereinafter, the transflective liquid crystal display device 1 shown in FIG. 2A will be described as an example. However, the transflective liquid crystal display device 1a shown in FIG. The operation is the same with the only difference in the arrangement.

  FIG. 1B is a diagram schematically showing an example of an optical fiber 15a and a spectral radiance sensor 16a different from the configuration shown in FIG. In the configuration shown in FIG. 1B, instead of the optical fiber 15, the first spectral radiance sensor 16, and the second spectral radiance sensor 18 shown in FIG. 16a and electronic shutters 19a, 19b1 to 19b4 are used.

  The optical fiber 15a guides and supplies the irradiation light obtained through the diffuser plate 14 to the spectral radiance sensor 16a, and guides and supplies the external light obtained through the four diffuser plates 17 to the spectral radiance sensor 16a. The optical fiber 15a is connected to the diffusion plate 14 via an electronic shutter 19a, and is connected to each of the four diffusion plates 17 via electronic shutters 19b1 to 19b4. The electronic shutters 19a, 19b1 to 19b4 are not opened at the same time, but are all closed or only one of them is opened.

  The spectral radiance sensor 16 a is a detection device that detects the spectral characteristics of incident light supplied from the optical fiber 15. The spectral radiance sensor 16a detects the spectral characteristics of the irradiation light obtained through the diffusion plate 14 when the electronic shutter 19a is open, and the electronic shutter 19b1 is connected when the electronic shutter 19b1 is open. When the electronic shutter 19b2 is opened, the spectral characteristic of the external light obtained through the diffusion plate 17 to which the electronic shutter 19b2 is connected is detected. When the electronic shutter 19b3 is open, the spectral characteristics of the external light obtained through the diffusion plate 17 to which the electronic shutter 19b3 is connected are detected, and when the electronic shutter 19b4 is open, the electronic shutter 19b4 is detected. The spectral characteristic of the external light obtained through the diffuser plate 17 connected to is detected.

  The first spectral radiance sensor 16, the second spectral radiance sensor 18 and the spectral radiance sensor 16a are constituted by, for example, a polychromator type spectral radiance meter using a diffraction grating or a filter type color luminance meter. A polychromator-type spectral radiance meter collects light to be measured with a lens, separates the collected light for each wavelength by a grating, that is, a diffraction grating, and converts the luminance for each wavelength to a plurality of photosensors, for example, photo It is measured with a diode array. The filter type color luminance meter is inferior in accuracy to the polychromator type spectral radiance meter. The first spectral radiance sensor 16 is first spectral characteristic detection means, and the second spectral radiance sensor 18 is second spectral characteristic detection means.

  In the configuration shown in FIG. 1A, the five spectral radiance sensors of the first spectral radiance sensor 16 and the four second spectral radiance sensors 18 are used, but the configuration shown in FIG. Requires only one spectral radiance sensor 16a, and the number of spectral radiance sensors can be reduced.

  In the example shown in FIG. 2, the example using the four second spectral radiance sensors 18 is shown, but the number of the second spectral radiance sensors 18 is not limited to four. Depending on the size, it may be two, three, or more than five.

  FIG. 3 is a block diagram showing a configuration of the transflective liquid crystal display device 1. The transflective liquid crystal display device 1 includes a central processing unit (abbreviated as CPU) 30 in addition to the first spectral radiance sensor 16 and the second spectral radiance sensor 18 shown in FIG. A storage device, an input terminal 31, an analog-digital (hereinafter referred to as "AD") conversion processing unit 32, a video signal processing unit 33, a driver processing unit 34, and a liquid crystal panel / light source unit 35.

  The CPU 30 serving as a control unit controls the video signal processing unit 33, the driver processing unit 34, and the liquid crystal panel / light source unit 35 by executing a program stored in a storage device (not shown). A storage device (not shown) is constituted by a semiconductor memory, for example, and stores a program executed by the CPU 30 and information used when the CPU 30 executes the program.

  The input terminal 31 receives, as analog signals, image information output from a receiving device that receives television broadcasts, image information reproduced by a recording / reproducing device that records and reproduces image information, or image information reproduced by a computer. This is the input terminal. The AD conversion processing unit 32 converts the image information of the analog signal input to the input terminal from an analog signal to a digital signal, and sends the converted image information of the digital signal to the video signal processing unit 33. Here, the image information input from the input terminal 31 may be a digital signal. In this case, the AD conversion processing unit 32 is not necessary.

  The video signal processing unit 33 which is a color correction unit performs color correction of image information received from the AD conversion processing unit 32 according to a command from the CPU 30, and sends the color-corrected image information to the driver processing unit 34. The color correction will be described later. The driver processing unit 34 converts the image information received from the video signal processing unit 33 from a digital signal to an analog signal, and sends the converted analog signal image information to the liquid crystal panel / light source unit 35. In addition, the driver processing unit 34 controls the liquid crystal panel / light source unit 35, for example, the LCD module 11, that is, the control of driving the backlight 13 and the luminance adjustment control of the backlight 13 in the liquid crystal panel. I do.

  The liquid crystal panel / light source unit 35 includes the LCD module 11, the half mirror 12, and the backlight 13 shown in FIG. The liquid crystal panel / light source unit 35 transmits only the reflected light from the half mirror 12, or the reflected light from the half mirror 12 and the irradiation light from the backlight 13, through the color filter of the LCD module 11, and the color of the image information. To develop color. The first spectral radiance sensor 16 sends the detected spectral characteristic to the CPU 30, and the second spectral radiance sensors 18 a to 18 d send the spectral characteristic detected by each to the CPU 30. Hereinafter, the spectral characteristic is also referred to as spectral radiance.

  The CPU 30 receives the spectral radiance received from the first spectral radiance sensor 16, the spectral radiance received from the second spectral radiance sensors 18a to 18d, the spectral transmittance of a color filter described later, and the spectral reflection of the half mirror 12. Parameter information, which is color correction information necessary for color correction to be performed by the video signal processing unit 33, is generated for each of the regions R1a to R1d based on the rate and a color matching function described later of the XYZ color system. The CPU 30 sends the four parameter information generated for each of the regions R1a to R1d to the video signal processing unit 33. The video signal processing unit 33 performs color correction on the image information received from the AD conversion processing unit 32 for each of the regions R1a to R1d based on the received four parameter information. The spectral radiance received from the first spectral radiance sensor 16 is the spectral radiance of the irradiation light from the backlight 13 and is simply referred to as the spectral radiance of the backlight or the spectral characteristics of the backlight.

  FIG. 4 is a graph 51 showing an example of the light source spectral luminance of the external light and the backlight. In the graph 51, the vertical axis represents luminance, and the horizontal axis represents wavelength (nm). The light source spectral luminance is the spectral radiance of light sources such as outside light and the backlight 13. The luminance is a percentage (%) display with respect to the maximum luminance. The light source spectral luminance of the backlight is the spectral radiance of a light source such as the backlight 13. In the graph 51, the luminance of the irradiation light from the backlight 13 (hereinafter, simply referred to as the luminance of the backlight) is measured by the first spectral radiance sensor 16 for each wavelength of 1 nm in the wavelength range from 380 nm to 780 nm. The light source spectral luminance 511 of the backlight and the light source spectral luminance 512 of the external light measured by the second spectral radiance sensor 18 are shown. In order to simplify the description, the spectral reflectance of the half mirror 12 is set to 100%, and the same applies to the following description.

The light source spectral luminance 511 of the backlight represents the luminance of the backlight at each wavelength with the maximum luminance of the luminance of the backlight measured for each wavelength being 100%. The light source spectral brightness 512 of external light represents the brightness of external light at each wavelength, with the maximum brightness being 100% of the brightness of external light measured for each wavelength. The light source spectral luminance 512 of the external light is high in a wide range with respect to the maximum luminance, but the light source spectral luminance 511 of the backlight is low in the range excluding the vicinity of the maximum luminance.

  The CPU 30 generates a backlight spectral luminance matrix L1 and generates an external light spectral luminance matrix L2 for each of the regions R1a to R1d. The backlight spectral luminance matrix L1 is a matrix representing the luminance for each wavelength indicated by the light source spectral luminance 511 of the backlight measured by the first spectral radiance sensor 16. The external light spectral luminance matrix L2 generated for each of the regions R1a to R1d represents the luminance for each wavelength indicated by the light source spectral luminance 512 of the external light obtained by measuring the luminance of the external light by the second spectral radiance sensors 18a to 18d, respectively. It is a matrix. Specifically, each of the backlight spectral luminance matrix L1 and the external light spectral luminance matrix L2 is a 401-row × 1-column matrix that represents the luminance at wavelengths of 1 nm in the wavelength range from 380 nm to 780 nm. It is.

  FIG. 5 is a graph 52 illustrating an example of the spectral transmittance of the color filter of the LCD module 11. The vertical axis represents the transmittance, and the horizontal axis represents the wavelength (nm). Graph 52 shows the luminance of each color obtained by separating white light transmitted through the color filter into three colors of RGB red, green, and blue, assuming that the luminance of the white light applied to the color filter is 100%. It is the graph which displayed the percentage (%) as a transmittance | permeability for every wavelength 1nm in the wavelength range from wavelength 380nm to 780nm.

  The spectral transmittance 521 is the transmittance of red light. The spectral transmittance 522 is the transmittance of green light. The spectral transmittance 523 is the transmittance of blue light. The spectral transmittance of the color filter of the LCD module 11 is measured in advance by a dedicated measuring device before being incorporated in the device, and the spectral transmittance of the color filter as a measurement result is not shown before shipment from the factory. Store in a storage device.

  The CPU 30 reads the spectral transmittance of the color filter from a storage device (not shown) immediately after the transflective liquid crystal display device 1 is turned on, and generates a spectral transmittance matrix C. The spectral transmittance matrix C is a matrix representing the luminance for each wavelength indicated by the spectral transmittance 521 for red light, the spectral transmittance 522 for green light, and the spectral transmittance 523 for blue light. Specifically, the spectral transmittance matrix C has a wavelength range from 380 nm to 780 nm, and the luminance at a wavelength of 1 nm increments is 401 rows and 1 column for red light, 401 rows and 1 column for green light, It is a matrix of 401 rows and 3 columns represented by a total of 3 columns of 401 rows and 1 column for blue light.

  FIG. 6 is a graph 53 illustrating an example of the spectral characteristics of the irradiation light of the backlight 13 when the color filter is transmitted. The vertical axis represents luminance, and the horizontal axis represents wavelength (nm). The graph 53 shows the luminance of each color obtained by separating the irradiation light of the backlight 13 transmitted through the color filter into three colors of red, green, and blue when the luminance of the white light irradiated on the color filter is 100%. It is the graph which displayed the percentage (%) for every wavelength 1nm in the wavelength range from wavelength 380nm to 780nm.

  The spectral characteristic 531 is a characteristic of red light. The spectral characteristic 532 is a characteristic of green light. The spectral characteristic 533 is a characteristic of blue light.

  The spectral characteristic 531 of red light, the spectral characteristic 532 of green light, and the spectral characteristic 533 of blue light in the graph 53 are the light source spectral luminance 511 of the backlight shown in FIG. 4 and the red light shown in FIG. The spectral transmittance 521, the green light spectral transmittance 522, and the blue light spectral transmittance 523 can be obtained. Specifically, the CPU 30 obtains a matrix obtained by multiplying the matrix elements of the backlight spectral luminance matrix L1 and the spectral transmittance matrix C, that is, a matrix of calculation results of L1 × C. A graph 53 is a plot of the matrix values of the L1 × C calculation results.

  FIG. 7 is a graph 54 showing an example of the spectral characteristics of external light when passing through the color filter. The vertical axis represents luminance, and the horizontal axis represents wavelength (nm). The graph 53 shows the luminance of each color obtained by separating the external light transmitted through the color filter into three colors of red, green, and blue when the luminance of the white light applied to the color filter is 100%. It is the graph which displayed the percentage (%) for every wavelength of 1 nm in the wavelength range up to.

  The spectral characteristic 541 is a characteristic of red light. The spectral characteristic 542 is a characteristic of green light. The spectral characteristic 543 is a characteristic of blue light.

  The spectral characteristic 541 of red light, the spectral characteristic 542 of green light, and the spectral characteristic 543 of blue light in the graph 54 are the light source spectral luminance 512 of external light shown in FIG. 4 and the red light shown in FIG. The spectral transmittance 521, the green light spectral transmittance 522, and the blue light spectral transmittance 523 can be obtained. Specifically, the CPU 30 obtains a matrix obtained by multiplying the matrix elements of the external light spectral luminance matrix L2 and the spectral transmittance matrix C, that is, a matrix of calculation results of L2 × C for each of the regions R1a to R1d. A graph 54 is a plot of the matrix values of the L2 × C calculation results.

  FIG. 8 is a graph 55 showing the visibility characteristics of the color matching function. The vertical axis represents tristimulus values, and the horizontal axis represents wavelength (nm). The color matching function shown in FIG. 8 is the color matching function of the XYZ display color system, the color matching function of the colorimetric standard observer defined by the standard CIE (Commission Internationale de I'Eclairage) 1931, and 2 ° It is a function defined by the visibility characteristics of the visual field.

  The visual sensitivity characteristic 551 of red light has a convex shape in which the tristimulus value is a maximum of about 0.4 near the wavelength of about 430 nm and a wavelength of about 500 nm to about 680 nm in the wavelength range of about 400 nm to about 500 nm. This is a visual sensitivity characteristic having two convex peaks where the tristimulus value is about 1.1 at the maximum around a wavelength of about 590 nm. The green light visibility characteristic 552 is a convex visibility characteristic in which the tristimulus value reaches a maximum of about 1.0 near the wavelength of about 560 nm in the wavelength range of about 420 nm to about 680 nm. The blue light visibility characteristic 553 is a convex visibility characteristic in which the tristimulus value reaches a maximum of about 1.8 near the wavelength of about 450 nm in the wavelength range of 380 nm to about 550 nm.

  The CPU 30 generates a color matching function matrix S representing the color matching function. Specifically, the CPU 30 reads the visual sensitivity characteristic of the color matching function from a storage device (not shown) immediately after the display device is turned on, and the color matching function matrix S based on the read visual sensitivity characteristic of the color matching function. Is generated. The color matching function matrix S is a matrix representing tristimulus values for each wavelength indicated by the red light visibility characteristic 551, the green light visibility characteristic 552, and the blue light visibility characteristic 553. The color matching function matrix S has a luminance in a wavelength range of 380 nm to 780 nm and a wavelength in increments of 1 nm, 401 rows and 1 column for red light, 401 rows and 1 column for green light, and 401 for blue light. It is a matrix of 401 rows and 3 columns represented by a total of 3 columns of 1 row.

The color signal of the image information input from the input terminal 31 is represented by the function f (R, G, B) in the RGB system, and the color signal represented by the function f (R, G, B) is irradiated by the backlight 13. When the color signal when the color is developed by is expressed by the function g1 (X, Y, Z) in the XYZ color system and the conversion matrix is expressed by M, the relationship of Expression (1) is established.
g1 (X, Y, Z) = f (R, G, B) · M (1)

Here, “·” is an operation symbol representing multiplication between matrices. Similarly, a color signal when the color signal represented by the function f (R, G, B) is developed by external light is represented by the function g2 (X, Y, Z) in the XYZ color system, and its conversion matrix. If N is represented by N, the relationship of Formula (2) is established.
g2 (X, Y, Z) = f (R, G, B) · N (2)

The conversion matrix M is expressed by the equation (3) using the color matching function matrix S, and the conversion matrix N is expressed by the equation (4) using the color matching function matrix S.
M = (S ^t · L1 × C) ^t (3)
N = (S ^t · L2 × C) ^t (4)

Here, “×” is an operation symbol representing multiplication of elements of a matrix. “ ^T ” is an operation symbol representing a transposed matrix. The transformation matrices M and N are 3 × 3 matrices.

The function g2 (X, Y, Z) representing the color signal when colored by external light matches the function g1 (X, Y, Z) representing the color signal when colored by the irradiation light from the backlight 13 By doing so, the color signal when the color is generated by the external light matches the color signal when the color is generated by the irradiation light from the backlight 13. When the correction matrix for matching the function g2 (X, Y, Z) representing the color signal when the color is developed with external light with the function g1 (X, Y, Z) is A, the relationship of Expression (5) is given. To establish.
g2 (X, Y, Z) · A = g1 (X, Y, Z) (5)

When each term on both sides of Equation (2) is multiplied by a matrix (N ⁻¹ × M) from the right side, Equation (2) becomes Equation (6). Here, “ ⁻¹ ” is an operation symbol representing an inverse matrix.
g2 (X, Y, Z) · N ⁻¹ · M = f (R, G, B) · N · N ⁻¹ · M
= F (R, G, B) · M (6)

Equation (6) can be transformed from Equation (1) to Equation (7).
g2 (X, Y, Z) · N ⁻¹ · M = g1 (X, Y, Z) (7)

From Equation (5) and Equation (7), the correction matrix A is A = N ⁻¹ · M.
The CPU 30 sends the correction matrix A to the video signal processing unit 33 as parameter information. The video signal processing unit 33 performs color correction based on the received parameter information. Specifically, the video signal processing unit 33 performs color correction by multiplying each pixel constituting the image represented by the image information by the correction matrix A from the right side.

FIG. 9 is a diagram for explaining an evaluation method for detecting a change in external light. The vertical axis represents the actual brightness value (mW / (sr · m ² · nm)) of Spectroscopic Co., Ltd., and the horizontal axis represents the wavelength (nm).

FIG. 9A shows a spectral radiance 561 that represents the luminance at the time point t1 for each wavelength, and a spectral radiance 562 that represents the luminance at the time point t2 for each wavelength. FIG. 9B is an enlarged view of the range 57 of the spectral radiance 561 and the spectral radiance 562 shown in FIG. For example, the time point t2 is a time point when a predetermined first time interval has elapsed from the time point t1.

  The difference between the spectral radiance at time t2 and the spectral radiance at time t1 is the average of the differences (absolute values) at each wavelength for each wavelength of 1 nm in the wavelength range of 380 nm to 780 nm (hereinafter referred to as “arithmetic mean”) en It shall be expressed as That is, when the difference (absolute value) of the luminance value at each wavelength is represented by ei (i = 1 to 401), the arithmetic mean en is represented by Expression (8).

  In FIG. 9B, the difference e161 at a wavelength of 161 nm and the difference e171 at a wavelength of 171 nm are shown as representatives.

  The CPU 30 detects the spectral radiance of external light every predetermined first time interval, for example, every hour, and the first evaluation determination value, for example, the time point t1, whose arithmetic mean en is a predetermined first threshold value. When the maximum brightness is 10% or more, it is determined that the external light has changed, new parameter information is calculated, the calculated parameter information is sent to the video signal processing unit 33, and color correction is performed based on the parameter information. Let it be done.

  Since the CPU 30 calculates the correction matrix only when the arithmetic mean en is equal to or greater than the first evaluation determination value, it is not necessary to generate parameter information every time, and the processing time is reduced when there is no need to calculate the correction matrix. Can do.

Further, the CPU 30 detects the spectral radiance of the external light at a predetermined first time interval, and determines the luminance value (cd /) from the detected spectral radiance (W / (sr · m ² · nm) of the external light. m ² ) with respect to the value obtained by converting the spectral radiance of the backlight into the luminance value, a ratio that is equal to or higher than the second evaluation determination value, for example, a ratio that the luminance of external light is twice or more of the luminance of the backlight. In some cases, the backlight 13 is turned off, and only the external light is displayed, and when the ratio of the luminance value of the external light to the luminance value of the backlight is less than the second evaluation determination value, the backlight 13 is turned on and the external light And display with the irradiation light of the backlight 13. Conversion from the spectral radiance to the luminance value is obtained by the integral value of the spectral radiance at 380 nm to 780 nm.

  FIG. 10 is a flowchart showing a processing procedure of a first color correction process in which the backlight 13 is turned off and color correction is performed. The first color correction process is a process for switching whether to display only with external light according to the luminance of external light. When the power of the transflective liquid crystal display device 1 is turned on and becomes operable, the CPU 30 proceeds to step A1. Also, when the spectral radiance of the external light becomes less than the spectral radiance of the backlight at the time of factory shipment, the process proceeds to step A1. The CPU 30 performs the first color correction process for each of the regions R1a to R1d.

  In step A <b> 1, the CPU 30 instructs the liquid crystal panel / light source unit 35 to turn on the backlight 13 and turns on the backlight 13. In step A2, the CPU 30 detects the spectral radiance of external light by the second spectral radiance sensors 18a to 18d at each predetermined first time interval. In step A3, the CPU 30 proceeds to step A4 when the spectral radiance of all the external lights detected by the second spectral radiance sensors 18a to 18d is larger than the spectral radiance of the backlight at the time of factory shipment. When the spectral radiance of the external light detected by at least one of the second spectral radiance sensors 18a to 18d is equal to or lower than the spectral radiance of the backlight at the time of factory shipment, the process returns to Step A1.

  In step A4, the CPU 30 instructs the liquid crystal panel / light source unit 35 to turn off the backlight 13, and turns off the backlight 13. In step A5, the CPU 30 determines the color of the XYZ color system for each of the regions R1a to R1d so that the color developed by the external light, that is, the color developed by the reflected light from the half mirror 12 matches the color developed by only the illumination light of the backlight 13. Correction calculation processing, that is, parameter information generation is performed. Then, the generated parameter information is sent to the video signal processing unit 33, color correction is performed based on the parameter information, and the first color correction process is terminated.

  FIG. 11 is a flowchart showing a processing procedure of a second color correction process for performing color correction using the backlight 13 together. The second color correction process is a process in the case where the backlight 13 is always used together without depending on the brightness of the external light. When the power of the transflective liquid crystal display device 1 is turned on and becomes operable, the CPU 30 proceeds to step B1. Further, each time the predetermined first time elapses, the process proceeds to Step B1. The CPU 30 performs the second color correction process for each of the regions R1a to R1d.

  In step B <b> 1, the CPU 30 detects the spectral radiance of external light by the second spectral radiance sensor 18. In step B <b> 2, the CPU 30 detects the spectral radiance of the backlight using the first spectral radiance sensor 16. In step B3, the CPU 30 performs correction calculation processing of the XYZ color system, that is, the coloration when the external light and the backlight 13 are used together matches the coloration due to only the irradiation light of the backlight 13 at the time of shipment from the factory. Generate parameter information. Then, the generated parameter information is sent to the video signal processing unit 33, color correction is performed based on the parameter information, and the second color correction process is terminated.

In this case, the above-described equation (4) is expressed as equation (9) using the backlight spectral luminance matrix L1 and the external light spectral luminance matrix L2.
N ′ = (S ^t · (L1 + L2) × C) ^t (9)

As a result, the correction matrix A ′ = N′− ¹ · M. Here, “+” is an operation symbol representing addition of matrices.

When considering the temporal change of the backlight 13, the CPU 30 determines the backlight 13 at a predetermined time, for example, at the time of factory shipment, and at a second time interval that is predetermined after the predetermined time, for example, every month. The first spectral radiance sensor 16 detects the spectral radiance. Then, the arithmetic mean en of the difference (absolute value) between the detected spectral radiance and the spectral radiance at the time of factory shipment is a third evaluation determination value that is a second threshold value determined in advance, for example, the maximum at the time of factory shipment. When the luminance is 10% or more, it is determined that the backlight 13 has changed with time. When determining that the backlight 13 has changed with time, the CPU 30 causes the backlight 13 to detect a color shift accompanying the change with time based on the detected spectral radiance of the backlight and the spectral radiance of the backlight at the time of shipment from the factory. A correction matrix B for correction is generated. Assuming that L1 changes to L1 ′ due to a change with time of the backlight, the above equation (3) is modified, and the correction matrix M ′ of equation (10) is also taken into consideration.
M ′ = (S ^t · L1 ′ × C) ^t (10)

As a result, the correction matrix B considering the change with time is B = N− ¹ · M′− ¹ · M. In step B3, the temporal change correction matrix B is sent as parameter information to the video signal processing unit 33, color correction is performed based on the parameter information, and the second color correction process is terminated.

  FIG. 12 shows xy chromaticity 60 when color correction is performed in the transflective liquid crystal display device 1. The xy chromaticity 60 is the xy chromaticity of the XYZ color system defined by CIE, the vertical axis is the y chromaticity of the xy chromaticity, and the horizontal axis is the x chromaticity of the xy chromaticity. A color gamut 605 is a color gamut of a color matching function according to CIE1931.

  The color gamut 601 is a color gamut when the color correction is performed for the color generation by the external light in the transflective liquid crystal display device 1, and the color gamut 602 is a color gamut at the time of color generation only by the backlight 13. is there. Since the boundary line of the color gamut 601 and the boundary line of the color gamut 602 coincide with each other, they actually overlap each other, but in FIG. In addition, the white point 603 when the color correction is performed for the coloration by the external light in the transflective liquid crystal display device 1 matches the white point 604 of the backlight 13 only.

  FIG. 13 is a side view schematically showing the appearance of the transmissive liquid crystal display device 2 according to the second embodiment of the present invention. FIG. 14 is a front view schematically showing the external appearance of the transmissive liquid crystal display devices 2 and 2a. The transmissive liquid crystal display device 2 as a display device includes an LCD module 21, a backlight 22, a diffusion plate 23, an optical fiber 24, and spectral radiance sensors 25, 28a to 28d. The LCD module 21, the diffusion plate 23, the optical fiber 24, and the spectral radiance sensor 25 have the same configuration as the LCD module 11, the diffusion plate 14, the optical fiber 15, and the first spectral radiance sensor 16 shown in FIG. Therefore, the description is omitted to avoid duplication. Further, the second spectral radiance sensors 28a to 28d shown in FIG. 14 have the same configuration as the second spectral radiance sensor 18, and each is provided with a diffusion plate 17. In FIGS. Not shown.

  The backlight 22 is configured by, for example, an edge light type backlight, and includes a light source (not shown) and a light guide plate (not shown). The backlight 22 is provided with four external light intakes 222 and four second spectral radiance sensors 28 at the peripheral edge 221 of the backlight 22. Each second spectral radiance sensor 28 is provided adjacent to each external light inlet 222. Each second spectral radiance sensor 28 detects the spectral radiance of the external light irradiated in the vicinity of the adjacent external light inlet 222 and sends the detected spectral radiance of the external light to the CPU 30.

  FIG. 14A is a front view schematically showing the appearance of the transmissive liquid crystal display device 2, and FIG. 14B shows a transmissive liquid crystal display device 2 a that is a modification of the transmissive liquid crystal display device 2. It is a front view which shows an external appearance typically. FIGS. 14A and 14B show the arrangement of the four external light intakes 222 and the four second spectral radiance sensors 28. The external light intake 222, which is an external light acquisition means, is a general term for the external light intakes 222a to 222d shown in FIG. 14A or the external light intakes 222e to 222h shown in FIG. 14B. The second spectral radiance sensor 28 is a general term for the second spectral radiance sensors 28a to 28d shown in FIG. 14A or the second spectral radiance sensors 28e to 28h shown in FIG. 14B.

  In the transmissive liquid crystal display device 2 shown in FIG. 14A, four external light intakes 222 and four second spectral radiance sensors 28 are provided, one set at each corner of the peripheral edge 221 of the backlight 22. Be placed. The display screen of the LCD module 21 shown in FIG. 14A is divided into four regions R2a to R2d by a straight line orthogonal to the center of the long side in the horizontal direction and a straight line orthogonal to the center of the short side in the vertical direction. ing. The second spectral radiance sensor 28a is a spectral radiance sensor for performing color correction of the region R2a, the second spectral radiance sensor 28b is a spectral radiance sensor for performing color correction of the region R2b, The second spectral radiance sensor 28c is a spectral radiance sensor for performing color correction of the region R2c, and the second spectral radiance sensor 28d is a spectral radiance sensor for performing color correction of the region R2d.

  In the transmissive liquid crystal display device 2 a shown in FIG. 14B, the four external light intakes 222 and the four second spectral radiance sensors 28 include the long side direction and the short side direction of the peripheral portion 221 of the backlight 22. One set is arranged at the center of each. The display screen of the LCD module 21 shown in FIG. 14B is divided into four regions R2e to R2h by two diagonal lines. The second spectral radiance sensor 28e is a spectral radiance sensor for performing color correction of the region R2e, and the second spectral radiance sensor 28f is a spectral radiance sensor for performing color correction of the region R2f, The second spectral radiance sensor 28g is a spectral radiance sensor for performing color correction of the region R2g, and the second spectral radiance sensor 28h is a spectral radiance sensor for performing color correction of the region R2h.

  Hereinafter, the transmissive liquid crystal display device 2 shown in FIG. 14A will be described as an example. However, the transmissive liquid crystal display device 2a shown in FIG. The operation is the same except that the arrangement of the spectral radiance sensor 28 is different.

  Each external light inlet 222 takes in external light coming from the front side of the LCD module 21. External light taken from each external light inlet 222 is supplied to the light guide plate. Moreover, the irradiation light emitted from the light source of the backlight 22 is also supplied to the light guide plate. The backlight 22 emits external light taken in from each external light inlet 222 and irradiation light emitted from the light source from the light guide plate and transmits the light from the back of the LCD module 21 to the front side of the LCD module 21. The external light taken in from the external light intake 222 is acquired external light.

  The diffusion plate 23 is provided below the backlight 22 in the surface direction of the LCD module 21 and is connected to the light guide plate. The diffusion plate 23 supplies the external light and the irradiation light to the optical fiber 24 by diffusing and transmitting the external light taken in from the external light inlet 222 emitted from the light guide plate and the irradiation light emitted from the light source. The spectral radiance sensor 25 detects the spectral characteristics of external light and irradiation light supplied from the optical fiber 24.

  Since the CPU 30 performs the same process as the second color correction process shown in FIG. 11, the description thereof is omitted to avoid duplication. Further, when measuring the spectral radiance of external light, it is possible to turn off the backlight 22 and detect the spectral radiance of only external light and perform the same processing as the first color correction processing.

  In the transmissive liquid crystal display devices 2 and 2a, there is a possibility that a color shift occurs in the color to be developed on both sides of the boundary line of each region due to color correction using a different correction matrix for each region. For pixels on both sides adjacent to each other, further correction may be added by a weighted average.

  The transmissive liquid crystal display device 2 uses a spectral radiance sensor 25 instead of the first spectral radiance sensor 16 shown in FIG. 1 and a second spectral radiance sensor 28 instead of the second spectral radiance sensor 18. Use. In the transmissive liquid crystal display device 2, the liquid crystal panel / light source unit 35 includes the LCD module 21 and the backlight 22 illustrated in FIG. 13 and does not include the half mirror 12.

  In the half mirror 12 shown in FIG. 1A, since the external light is attenuated by the LCD module 11, the reflected light from the half mirror 12 is weak. However, the transmissive liquid crystal display device 2 shown in FIG. Since the entrance 222 is provided so that the external light itself can be used as a backlight, light stronger than the reflected light from the half mirror 12 can be supplied to the LCD module 21.

  In the example shown in FIG. 14, an example in which four external light intakes 222 and four second spectral radiance sensors 28 are used is shown. However, the number of external light intakes 222 and second spectral radiance sensors 18 is as follows. None of them is limited to four, and for example, it may be two, three, or five or more, depending on the size of the display screen.

  In the embodiment described above, an arithmetic mean is used to detect a change in external light and a change in the backlight 13 with time, but it is also possible to make a determination based on the luminance at a representative wavelength, for example, a wavelength of 550 nm. .

As described above, the irradiation light emitted from the backlight 13 provided on the back side of the display screen of the LCD module 11 that displays image information on the display screen divided into a plurality of areas, and the LCD module 11 and the backlight 13. The reflected light from the half mirror 12 provided therebetween or the acquired external light acquired by the external light inlet 222 provided at the peripheral edge of the LCD module 11, or the reflected light or the acquired external light to the LCD module 11. In developing the color of the image information by transmitting the provided color filter, the first spectral radiance sensor 16 detects the spectral characteristics of the irradiation light expressed by a predetermined wavelength interval in a predetermined wavelength range. The plurality of second spectral radiance sensors 18 are provided in correspondence with each of the plurality of regions at the peripheral edge of the display screen of the LCD module 11, and have a predetermined wavelength with respect to external light irradiated on the LCD module 11 from the outside. Spectral characteristics represented by a predetermined wavelength interval in the range are detected. The video signal processing unit 33 performs color correction of image information to be displayed on the LCD module 11, and supplies the image information subjected to color correction to the LCD module 11 for display. Then, the CPU 30 causes the first spectral radiance sensor 16 to detect the spectral characteristic of the irradiation light , causes the second spectral radiance sensor 18 to detect the spectral characteristic of external light , and detects the spectral characteristic of the external light. Parameter information for each region is generated based on the luminance value obtained from the spectral characteristic of the irradiated light and the luminance value obtained from the spectral characteristic of the external light detected by the plurality of second spectral radiance sensors 18. Then, the generated parameter information is supplied to the video signal processing unit 33, and based on the supplied parameter information, the video signal processing unit 33 performs color correction of the image information to be displayed for each region. In the case of the transmissive liquid crystal display device 2, the LCD module 11 is the LCD module 21, the backlight 13 is the backlight 22, and the first spectral radiance sensor 16 and the second spectral radiance sensor 18 are spectral radiance. The same applies to the following.

  Therefore, it is possible to correct color misregistration for each area of the screen due to the influence of external light or the like. In particular, in the digital signage using the display device, for example, the transflective liquid crystal display device 1 or the transmissive liquid crystal display device 2 capable of increasing the brightness with external light, the first spectral characteristic detecting means, for example, the first The spectral characteristic of the irradiation light from the backlight 13 is detected by one spectral radiance sensor 16, and the spectral characteristic of external light is detected by a plurality of second spectral characteristic detection means, for example, the second spectral radiance sensor 18. Further, by performing color correction for each region based on the detected spectral characteristics, it is possible to prevent a decrease in visibility due to the influence of external light or a change with time of the backlight 13, and the transflective liquid crystal display device 1 or the transmissive liquid crystal display. The device 2 can improve the backlight illumination mode, the external light mode, and the problem of color shift and insufficient brightness in the backlight illumination and the external light mode. .

  In addition, in both outdoor installations affected by external light and indoor installations that depend on backlight illumination, there is no color shift even if the same image is displayed. The display device can be used both outdoors and indoors without giving a sense of incongruity.

  Further, the CPU 30 is provided in the LCD module 11 for each of the regions, the spectral characteristics of the irradiation light detected by the first spectral radiance sensor 16 and the spectral characteristics of the external light detected by the second spectral radiance sensor 18. A correction matrix for color correction is calculated based on the spectral transmittance of the color filter and the color matching function, and the calculated correction matrix is used as parameter information. Therefore, a correction matrix, which is parameter information that can correct color misregistration more accurately, can be calculated for each region.

Further, the CPU 30 causes the second spectral radiance sensor 18 to detect the spectral characteristics of the external light applied to the LCD module 11 from the outside for each of the regions at predetermined first time intervals. Then, the difference between the luminance values obtained from the spectral characteristics of external light at the elapsed point of said first time interval from the brightness values obtained from the spectral characteristics of the external light and the first time in the first time the predetermined Is equal to or greater than a predetermined first threshold, parameter information is generated. Accordingly, when the degree of color shift of the display color due to the performance degradation due to the time change of the external light is small, the calculation process for performing the color correction can be omitted, so that the screen display is not delayed.

Further, the CPU 30 causes the first spectral radiance sensor 16 to detect the spectral characteristics of the irradiation light from the backlight 13 every time a predetermined time point elapses from the predetermined time point. The difference between the luminance value obtained from the spectral characteristic at the predetermined time point and the luminance value obtained from the spectral characteristic detected each time the predetermined period elapses from the predetermined time point is equal to or greater than a predetermined second threshold value. The difference in luminance value is greater than or equal to the second threshold based on the spectral characteristic at the predetermined time point and the spectral characteristic when the difference in luminance value is greater than or equal to the second threshold. the color of the image data to be developed by the irradiation light when it is configured to generate the color correction information to match the color of the image data to be developed by the irradiation light at the time the predetermined, video signals generated color correction information This is supplied to the processing unit 33.

  Therefore, even if a change due to aging occurs in the light irradiated by the backlight 13 used in the display device, the color shift due to the deterioration of the performance of the backlight 13 is suppressed by performing color correction for the aging change. Color display that is equivalent to the state of the display device at the time of shipment from the factory can be maintained.

Further, the CPU 30 determines that the luminance value obtained from the spectral characteristics of the external light detected by at least one of the plurality of second spectral radiance sensors 18 is the first spectral radiance. When it is less than the luminance value obtained from the spectral characteristics of the irradiation light detected by the sensor 16, the backlight 13 is irradiated with the irradiation light. Then, based on the spectral characteristics of the irradiation light detected by the first spectral radiance sensor 16 and the spectral characteristics of the external light detected by the plurality of second spectral radiance sensors 18, the irradiation light and the reflected light or For matching the color of the image information that is developed when the acquired external light is transmitted through the color filter with the color of the image information that is developed by transmitting only the irradiation light from the backlight 13 through the color filter. Parameter information is generated for each region.

  Therefore, when the luminance of the external light is insufficient, the luminance can be supplemented by the light emitted from the backlight 13, and the color of the image information can be colored by the light that is a combination of the light emitted from the backlight 13 and the external light. . Since parameter information for performing color correction, for example, a correction matrix, is obtained for each region and color correction is performed based on the spectral characteristics of light emitted from the backlight 13 and external light, only the light emitted from the backlight 13 is used. The same color display can be obtained.

Further, CPU 30, the at wavelength intervals to determine the advance for the wavelength range predetermined calculates a difference between the respective luminance values obtained from the two spectral characteristics, the calculated average of the sum of the difference, the difference of the luminance values And Therefore, even if the luminance changes depending on the wavelength, the difference between the two spectral characteristics can be obtained.

  Furthermore, since the spectral characteristic is a luminance characteristic expressed for each wavelength in the visible light region (380 to 780 (nm)), it can be corrected for each wavelength, and color misregistration can be corrected more accurately.

  Furthermore, it further includes diffusion plates 14 and 17 for diffusing irradiated light and external light. The first spectral radiance sensor 16 and the first spectral radiance sensor 18 have the spectral characteristics of the light diffused by the diffusion plates 14 and 17. Since it detects, appropriate brightness | luminance can be detected even if there is local intensity | strength strength.

  Further, since the optical fiber 15 that guides part of the irradiation light emitted from the backlight 13 to the first spectral radiance sensor 16 is further included, even if the first spectral radiance sensor 16 is provided separately, the attenuation of light is suppressed. be able to.

  Furthermore, since the optical fiber 24 guides the external light acquired by the plurality of external light intakes 222 to the spectral radiance sensor 25, the attenuation of the light can be suppressed even for the external light.

  Further, the display device is a transflective liquid crystal display device 1 including an LCD module 11, a backlight 13 and a half mirror 12. Accordingly, the transflective liquid crystal display device 1 can be realized by the irradiation light from the backlight 13 and the reflected external light, and the deterioration of the visibility due to the external light can be prevented, and the color shift and the luminance change due to the external light can be suppressed. it can.

  Further, the display device is a transmissive liquid crystal display device 2 including an LCD module 21, a backlight 22, and an external light inlet 222. The external light intake 222 is an external light acquisition opening provided at the peripheral edge of the backlight 22, and the backlight 22 includes a light guide plate portion that guides external light. The plurality of second spectral radiance sensors 18 are disposed in proximity to each of the external light intakes 222. Accordingly, the transmission type liquid crystal display device 2 is realized by the irradiation light from the backlight 22 and the acquired external light by the plurality of openings and the light guide plate, and the visibility is not deteriorated by the external light. And a change in luminance can be suppressed.

DESCRIPTION OF SYMBOLS 1 Transflective-type liquid crystal display device 2 Transmission-type liquid crystal display device 11,21 LCD module 12 Half mirror 13,22 Backlight 14,17,23 Diffusing plate 15,15a, 24 Optical fiber 16 1st spectral radiance sensor 16a, 25 Spectral radiance sensor 18 Second spectral radiance sensor 19a, 19b Electronic shutter 30 CPU
31 Input Terminal 32 AD Conversion Processing Unit 33 Video Signal Processing Unit 34 Driver Processing Unit 35 Liquid Crystal Panel / Light Source Unit

Claims (10)

Provided between the display means and the backlight means, the irradiation light emitted by the backlight means provided on the back side of the display screen of the display means for displaying the image information on the display screen divided into a plurality of areas. A color filter provided on the display means by reflected light from a half mirror or obtained outside light obtained by a plurality of outside light obtaining means provided at a peripheral portion of the display means, or the reflected light or obtained outside light. A display device that develops the color of image information by transmitting
A first spectral characteristic detecting means for detecting a spectral characteristic represented by a predetermined wavelength interval in a predetermined wavelength range for the irradiation light;
Provided in correspondence to each of the plural areas on the periphery of display screen of the display unit, the external light irradiated from the outside to the display means, the spectral characteristics represented by wavelength interval predetermined in the wavelength range of predetermined A plurality of second spectral characteristic detecting means for detecting;
Color correction means for performing color correction of image information to be displayed on the display means, and supplying the image information on which color correction has been performed to the display means;
Wherein to detect a spectral characteristic of the illumination light to the first spectral characteristic detecting means, and to detect the spectral characteristics of external light to the plurality of second spectroscopic characteristic detection means, detecting the first spectral characteristic detecting means Based on the spectral characteristics of the irradiated light and the spectral characteristics of the external light detected by the plurality of second spectral characteristics detecting means, color correction information for each region is generated, and the generated color correction information is converted into the color Control means for supplying to the correction means, and causing the color correction means to perform color correction of image information to be displayed for each region based on the supplied color correction information ,
The control means includes
The luminance value obtained from the spectral characteristic of the external light detected by at least one second spectral characteristic detection unit among the plurality of second spectral characteristic detection units is detected by the first spectral characteristic detection unit. When it is less than the luminance value obtained from the spectral characteristics of the irradiation light, the backlight means is irradiated with the irradiation light,
A backlight spectral luminance matrix representing a luminance value for each wavelength with respect to a predetermined range of wavelengths of the irradiation light is L1, and an external light spectral luminance matrix representing a luminance value for each wavelength with respect to the predetermined range of wavelengths of the external light. L2, where C is a spectral transmittance matrix of a color filter representing spectral transmittance for each wavelength with respect to a predetermined range of wavelengths, and S is a color matching function matrix representing luminance values for each wavelength with respect to a predetermined range of wavelengths. The correction matrix A is calculated by the following formula,
A = {(S ^t · (L1 + L2) × C) ^t } ⁻¹ · (S ^t · L1 × C) ^t
(In the above equation, “t” is a transposed matrix, “+” is an addition of matrices, and “−1” is an operation symbol representing an inverse matrix.)
The correction matrix A calculated for each region is supplied to the color correction unit as the color correction information,
The color correction unit corrects a color signal representing image information for each region based on the correction matrix A, and transmits the irradiation light and the reflected light or the acquired external light to the color filter. The display device is characterized in that the color of the image information that is colored is matched with the color of the image information that is colored by transmitting only the irradiation light through the color filter . The control means is provided for each region.
The spectral characteristics of external light irradiated from the outside to the display means, is detected in the second spectral characteristic detecting means for each first time interval predetermined,
A luminance value obtained from the spectral characteristics of the external light at the first time the predetermined luminance obtained from the spectral characteristics of the external light at the second time from said first time first time interval has elapsed The color correction information is newly generated based on a spectral characteristic of the external light at a second time when a difference from a value is equal to or greater than a predetermined first threshold. Display device. The control means includes
The spectral characteristic of the light emitted from the backlight unit is detected by the first spectral characteristic detection unit every time a predetermined period of time elapses from a predetermined time point and the predetermined time point,
The difference between the luminance value obtained from the spectral characteristic at the predetermined time point and the luminance value obtained from the spectral characteristic detected every time the predetermined period elapses from the predetermined time point is equal to or greater than a predetermined second threshold value. The difference in luminance value is equal to or greater than the second threshold based on the spectral characteristic at the predetermined time point and the spectral characteristic when the difference in luminance value is equal to or greater than the second threshold. the color of the image information to be colored by irradiation light when the generating the color correction information to match the color of the image information to be developed by the irradiation light at the time the predetermined, the generated the color correction information, the color the display device according to claim 1 or 2, characterized in that to supply to the correction unit. Wherein, at said wavelength intervals predetermined for the pre-determined wavelength range, calculates a difference between the respective luminance values obtained from the two spectral characteristics, the calculated average of the sum of the difference, the difference of the luminance values the display device according to claim 2 or 3, characterized in that a. The spectral characteristics A display device according to any one of claims 1-4, characterized in that the luminance characteristic represented for each wavelength in the visible light region. A diffusion plate for diffusing the irradiation light and the acquisition external light;
The first spectral characteristic detection unit and the plurality of second spectral characteristic detection units detect spectral characteristics of light diffused by a diffuser plate, according to any one of claims 1 to 5. The display device described. Display device according to any one of claims 1-6, characterized in that it further comprises an optical fiber for guiding a part of the irradiation light the backlight unit for irradiating the first spectral characteristic detecting means. The display device according to claim 7 , wherein the optical fiber guides external light acquired by the external light acquisition unit to the second spectral characteristic detection unit. The display means, the display device according to any one of claims 1-8, characterized in that said a transflective liquid crystal display device including the backlight unit and the half mirror. A transmissive liquid crystal display device including the display means, the backlight means and the external light acquisition means;
The external light acquisition means is an opening for acquiring external light provided at a peripheral portion of the backlight means,
The backlight means includes a light guide plate portion that guides external light,
It said plurality of second spectral characteristic detecting means, a display device according to any one of claims 1-8, characterized in that respectively arranged in proximity to each of the external light acquiring means.

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