JP2014041229A - Liquid crystal display device, and drive control method of liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recognize a change in intensity of light emitted from a light source and made incident on a liquid crystal display element by light intensity recognition means, correcting a gamma value with high accuracy to have appropriate electro-optical characteristics according to the light intensity, so as to provide a high-quality liquid crystal display device.SOLUTION: A liquid crystal display device includes: a light source; a liquid crystal display element that modulates light from the light source to generate an image; a control unit 70 that controls signals applied to the liquid crystal display element; a storage unit 60 that stores a gamma value and the like; light intensity recognition means 80 for recognizing a change in intensity of light emitted from the light source and irradiates the liquid crystal display element; and gamma value correction means for correcting the gamma value in the storage unit 60 on the basis of a result of light intensity detection means.

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal projector.

  2. Description of the Related Art Conventionally, there is a liquid crystal projector using a liquid crystal display element as image modulation means of a projection display device. As a liquid crystal display element used for a liquid crystal projector, for example, there is dielectric anisotropy between a first transparent substrate having a common electrode and a second transparent substrate having a transparent electrode and wiring, a switching element and the like forming a pixel. Encloses a positive nematic liquid crystal. A so-called TN (Twisted Nematic) liquid crystal display element in which the major axis of liquid crystal molecules is continuously twisted by 90 ° between two glass substrates is used. In addition to such a transmissive liquid crystal display element, a nematic having a negative dielectric anisotropy between a transparent substrate having a common electrode and a circuit substrate having a reflective electrode, a wiring, a switching element, etc. on one substrate. Enclose the liquid crystal. There is also a type using a so-called VAN (Vertical Alignment Nematic) liquid crystal type reflective liquid crystal display element in which the major axis of liquid crystal molecules is homeotropically aligned substantially perpendicularly to the two substrates.

  As a liquid crystal display element, an ECB (Electrically Controlled Birefringence) effect is used, retardation is applied to the light wave passing through the liquid crystal layer, and the action (modulation) for changing the polarization state of the light wave is controlled. The forming method is mainly used.

  The design of a general liquid crystal display element is a linear polarization state in which incident light is made to enter a light wave whose polarization is changed into a linear polarization state in a predetermined direction via a polarization control means such as a polarizer, and vibrates in this predetermined direction. When the light passes through, polarization modulation is performed. For example, a liquid crystal display element based on normally white is designed to give a retardation of only a half wavelength at the incident light wavelength (the center of gravity wavelength of a certain light wavelength band) in a state where no voltage is applied to the liquid crystal layer. In addition, a liquid crystal display element based on normally black has a minimum retardation applied to the liquid crystal layer in a state where no voltage is applied to the liquid crystal layer, and a retardation of only a half wavelength when a predetermined voltage is applied to the liquid crystal layer. Designed to give. The light given half-wave retardation is emitted after the vibration direction is changed to a direction perpendicular to the vibration direction of the linearly polarized light before entering. After that, the polarization control means such as a polarizer having a crossed Nicols arrangement with the polarization control means arranged on the incident side is arranged on the output side to select the polarization state, and the selected light is transmitted. ing. In contrast to this design, when the voltage applied to the liquid crystal layer is controlled using the ECB effect, the liquid crystal molecules cause a tilt operation, and the birefringence amount in the thickness direction of the liquid crystal layer decreases or increases. Therefore, the light wave that has passed through the liquid crystal layer becomes an elliptically polarized state according to the voltage applied to the liquid crystal layer, and the light component whose vibration direction has not been orthogonally transformed is blocked by the polarization control means arranged on the light exit side, It is configured to modulate the intensity of incident light.

  In the liquid crystal display device as described above, it is known that the electro-optical characteristics of the liquid crystal display element change when the light from the light source is irradiated onto the liquid crystal display element and the temperature of the liquid crystal display element changes. Due to the change in the electro-optical characteristics of the liquid crystal display element, the brightness or color of the image displayed on the liquid crystal display device changes, resulting in degradation of image quality. In a liquid crystal display device that provides higher quality images, it is necessary to always perform temperature compensation for these temperature changes.

  Therefore, there is a known method for detecting the temperature of the liquid crystal display element and compensating for the change in electro-optical characteristics caused by the change in the temperature of the liquid crystal display element by changing the amplitude of the signal voltage applied to the liquid crystal display element. (See Patent Document 1).

  In addition, in order to compensate for the deterioration in image quality caused by changes in the brightness or color of the image displayed on the liquid crystal display device according to the brightness of the external environment, the pixels of the liquid crystal display element are used. A means is known in which a light detection element is disposed on a substrate on which a switching element is disposed, and the luminance of a light source of a liquid crystal display device is changed according to the output (see Patent Document 2).

Japanese Patent No. 2589567 JP 2006-30392 A

  However, in a projection type liquid crystal display device in which the amount of light from the light source is strong, even if the temperature of the liquid crystal display element is equal, the amount of light incident on the liquid crystal display element changes, thereby changing the electro-optical characteristics of the liquid crystal display element. I found. FIG. 4 shows changes in the electro-optical characteristics of the liquid crystal display element with respect to changes in the amount of light. This indicates that the alignment state of the liquid crystal molecules changes due to the energy of the amount of light incident on the liquid crystal display element, and the electro-optical characteristics change accordingly.

  When the electro-optical characteristics of the liquid crystal display element change, the brightness, color, etc. of the image displayed on the liquid crystal display device change, resulting in degradation of image quality.

  Accordingly, an object of the present invention is to provide a liquid crystal display device that recognizes that the amount of light from the light source irradiated to the liquid crystal display element has changed and can compensate for the change in electro-optical characteristics. .

In order to achieve the above object, the liquid crystal display device of the present invention comprises:
A liquid crystal display device for displaying an image, a light source, a liquid crystal display element that modulates light from the light source and generates an image, a control unit that controls a signal applied to the liquid crystal display element, a gamma value, and the like And a light amount recognizing unit for recognizing a change in light amount from the light source irradiated on the liquid crystal display element, and the gamma value is determined in the storage unit based on a result of the light amount detecting unit. Gamma value correcting means for correcting is provided.

  According to the present invention, in the liquid crystal display device, it is possible to recognize a change in the amount of light from the light source irradiated to the liquid crystal display element, and to accurately compensate for a change in electro-optical characteristics accompanying the change in the amount of light.

FIG. 3 is a configuration diagram of a drive control unit of a liquid crystal display element of a liquid crystal display device according to a first embodiment of the present invention. It is a block diagram of the liquid crystal display device of this invention. 4 is a flowchart illustrating a gamma value correction procedure based on a change in light amount according to the present invention. It is a figure which shows the change of the electro-optical characteristic of a liquid crystal display element by the light quantity from a light source changing. It is a figure which shows the arrangement | positioning location of the optical sensor by 1st Example of this invention. It is a figure which shows the gamma value table of the liquid crystal display element of this invention.

  Hereinafter, a liquid crystal display device 1 according to an embodiment of the present invention will be described with reference to the accompanying drawings.

  Here, FIG. 2 is a configuration diagram showing the liquid crystal display device 1.

  The liquid crystal display device 1 has a function of displaying an image on the screen 200. In this embodiment, the liquid crystal display device 1 is a projection type liquid crystal display device equipped with a reflective liquid crystal display element (an image forming element such as a reflective liquid crystal display element). The liquid crystal display device 1 includes a housing 1a, a lamp 10, an illumination optical system 20, a color separation / synthesis optical system 30, a projection lens optical system 40, a liquid crystal display element 50, a storage unit 60, and a control unit 70. Have

  The housing 1a fixes and accommodates members constituting the liquid crystal display device 1. The housing 1a is a rectangular cube in this embodiment. In addition, in the housing 1a, a part of the projection lens optical system 40 is exposed to the outside. And the housing | casing 1a has the adjustment mechanism which adjusts the inclination of the liquid crystal display device 1, for example. A part of the projection lens optical system 40 is exposed to the outside in this embodiment, but may be housed in the housing 1a.

  The lamp 10 has a function of generating light. The lamp 10 includes an arc tube 11 and a reflector 12. In this case, γ is the optical axis of the liquid crystal display device 1.

  The arc tube 11 has a function of emitting white light with a continuous spectrum. The arc tube 11 is supplied with power by a power supply unit (not shown).

  The reflector 12 has a function of collecting light from the arc tube 11 in a predetermined direction. Therefore, the reflector 12 is configured by a mirror or the like having a high reflectance, and has a hemispherical shape.

  The illumination optical system 20 has a function of transmitting light from the lamp 10 to the color separation / synthesis optical system 30. The illumination optical system 20 includes cylinder arrays 21 and 22, an ultraviolet absorption filter 23, a polarization conversion element 24, a front compressor 25, a total reflection mirror 26, a condenser lens 27, and a rear compressor 28.

  The cylinder arrays 21 and 22 are composites of photosensitive elements incorporated in a camera, a detector, a scanning device, and the like. The cylinder array 21 is a lens array having a refractive power in a direction perpendicular to the optical axis γ. The cylinder array 22 has a lens array corresponding to each lens of the cylinder array 21. In this embodiment, the cylinder array 21 is disposed in front of the lamp 10, and the cylinder array 22 is disposed in front of an ultraviolet absorption filter 23 described later.

  The ultraviolet absorption filter 23 has a function of absorbing ultraviolet rays. The ultraviolet absorption filter 23 is disposed between the cylinder array 21 and the cylinder array 22.

  The polarization conversion element 24 has a function of converting non-polarized light into predetermined polarized light. The polarization conversion element 24 is disposed in front of the cylinder array 22.

  The front compressor 25 is composed of a cylindrical lens having a refractive power in the horizontal direction. The front compressor 25 is disposed in front of the polarization conversion element 24.

  The total reflection mirror 26 has a function of reflecting light from the lamp 10. The total reflection mirror 26 converts the optical axis by 90 degrees in this embodiment. The total reflection mirror 26 is disposed in front of the front compressor 25.

  The condenser lens 27 collects light from the lamp 10 and illuminates the object evenly by forming an image of the light source in the pupil of the projection lens. The condenser lens 27 is disposed in front of the total reflection mirror 26.

  The rear compressor 28 is composed of a cylindrical lens having a refractive power in the horizontal direction. The rear compressor 28 is disposed in front of the condenser lens 27.

  The color separation / synthesis optical system 30 has a function of decomposing and synthesizing light from the lamp 10. The color separation / synthesis optical system 30 includes a dichroic mirror 31, a polarizing plate 32, a polarizing beam splitter 33, a ¼ wavelength plate 35, and a color selective phase difference plate 36.

  The dichroic mirror 31 reflects light in the blue (B) and red (R) wavelength regions and transmits light in the green (G) wavelength region. The dichroic mirror 31 is disposed in front of the rear compressor 28.

  The polarizing plate 32 has a function of transmitting only S-polarized light. The polarizing plate 32 includes polarizing plates 32a, 32b, and 32c. The polarizing plate 32a is a green incident-side polarizing plate in which a polarizing element is bonded to a transparent substrate, and transmits only S-polarized light. The polarizing plate 32 a is disposed in front of the dichroic mirror 31. The polarizing plate 32b is a red-blue incident-side polarizing plate in which a polarizing element is bonded to a transparent substrate, and transmits only S-polarized light. The polarizing plate 32 b is disposed in front of the dichroic mirror 31. The polarizing plate 32c is an emission-side polarizing plate (polarizing element) for red and blue in which a polarizing element is bonded to a transparent substrate, and transmits only S-polarized light.

  The polarization beam splitter 33 transmits P-polarized light and reflects S-polarized light. The polarization beam splitter 33 has a polarization separation surface. The polarization beam splitter 33 includes polarization beam splitters 33a, 33b, and 33c. The polarization beam splitter 33a transmits P-polarized light and reflects S-polarized light. The polarizing beam splitter 33a is disposed in front of the polarizing plate 32a. The polarization beam splitter 33b transmits P-polarized light and reflects S-polarized light. The polarization beam splitter 33b is disposed in front of the color selective phase difference plate 36a. The polarization beam splitter 33c transmits P-polarized light and reflects S-polarized light. The polarization beam splitter 33c is disposed in front of the polarization beam splitter 33a.

  The quarter wave plate 35 has a function of giving a phase difference. The quarter wavelength plate 35 includes quarter wavelength plates 35R, 35G, and 35B. The quarter wavelength plate 35R is disposed between the polarization beam splitter 33b and a liquid crystal display element 50R described later. The quarter wavelength plate 35G is disposed between the polarization beam splitter 33a and a liquid crystal display element 50G described later. The quarter wavelength plate 35B is disposed between the polarization beam splitter 33b and a liquid crystal display element 50B described later.

  The color selective phase difference plate 36 has a function of converting the polarization direction of specific light by 90 degrees. The color selective phase difference plate 36a converts the polarization direction of blue light by 90 degrees and does not convert the polarization direction of red light. The color selective phase difference plate 36a is disposed between the polarizing plate 32b and the polarizing beam splitter 33b. The color selective phase difference plate 36b converts the polarization direction of the red light by 90 degrees and does not convert the polarization direction of the blue light. The color selective phase difference plate 36b is disposed between the polarizing plate 32c and the polarizing beam splitter 33b.

  The projection lens optical system (projection means) 40 irradiates light from the lamp 10 via the illumination optical system 20 and the color separation / synthesis optical system 30. The projection lens optical system 40 is composed of a plurality of optical elements (not shown) in the lens barrel 40a.

  As the present embodiment, the liquid crystal display device 1 is irradiated to the liquid crystal display element 50, a control unit 70 that controls a signal applied to the liquid crystal display element 50, a storage unit 60 that stores a gamma value and the like, and the liquid crystal display element 50. Possesses a light amount recognition means 80 for recognizing a change in the amount of light from the light source 10 and a gamma value light amount correction calculation circuit 74 for performing a calculation for correcting the gamma value according to the light amount.

  The control unit 70 calculates an input signal input from an external input device 300 using a gamma value table 72 corresponding to the amount of light incident on the liquid crystal display element 50 owned by the image generation unit 71. The calculated output is converted into an analog voltage by the DA converter 73 and applied to the liquid crystal display element 50.

  In addition, the storage unit 60 has a gamma value light amount correction function memory 61 having a value for correcting the gamma value table according to the recognition result of the light amount recognition means 80, and further a gamma value corresponding to a display mode for changing brightness and image quality. The gamma value table memory 62 that owns the table is owned.

  In addition, it owns a gamma value light amount correction calculation circuit 74 for calculating the output of the gamma value table memory 62 and the output of the gamma value light amount correction function memory 61.

  A means for light quantity compensation by the liquid crystal display device 1 according to the present configuration will be described.

  When the amount of light from the light source 10 incident on the liquid crystal display element 50 changes while using the liquid crystal display device 1, the light amount recognition means 80 recognizes the current amount of light incident on the liquid crystal display element 50. , Output the result.

  As the light amount recognizing means of the light amount recognizing means 80, the number of light sources 10 used in the liquid crystal display device 1, changes in output, changes in light amount over time, and optical filters and apertures not shown between the light source 10 and the liquid crystal display element 50 are used. A means for recognizing changes in the amount of light caused by insertion into the camera is provided.

  In the present embodiment, the operation when the output of the light source 10 of the liquid crystal display device 1 is changed will be described based on the flowchart shown in FIG.

  The light quantity recognizing means 80 recognizes that the user has set the mode for reducing the brightness of the liquid crystal display device 1, and starts the light quantity gamma adjustment (Step 1).

  The recognized light quantity is transmitted from the light quantity recognition means 80 to the gamma value light quantity correction function memory 61. For example, when the user decreases the brightness of the light source 10 by 20%, 0.8 is transmitted as the light amount value to the gamma value light amount correction function memory 61 (Step 2).

  Next, the correction amount of the gamma value corresponding to the light amount value transmitted from the light amount recognition means 80 is calculated from the gamma value light amount correction function memory 61 (Step 3). As a method for calculating the correction amount of the gamma value, it is possible to accurately correct a change in the light amount without increasing the number of memories by obtaining a correction amount corresponding to the light amount from an equation approximated by a function.

  Then, the gamma value correction amount corresponding to the calculated light amount and the gamma value stored in the currently selected gamma value table memory 62 are added together by the gamma value light amount correction calculation circuit 74 (Step 4). The added gamma value is a gamma value suitable for the current light amount of the light source 10 of the liquid crystal display device 1.

  The obtained gamma values are sequentially transmitted to the buffer memory 63 (Step 5).

  Then, the gamma values stored in the buffer memory 63 are sequentially transmitted to the gamma value table memory 72 corresponding to the amount of light in the image generation unit 71 (Step 6).

  Step 3 to Step 6 are repeated until transmission of the gamma value to the gamma value table memory 72 is completed for all the constituent colors and all the gradations of the liquid crystal display device 1 (Step 7). In this embodiment, the liquid crystal display device 1 is composed of three colors of RGB, and the gradation range is divided into 12 bits to perform processing.

  Specifically, among the values of the gamma value light amount correction table stored in the buffer memory 63, first, the gamma value light amount correction table for the gradation of the region 1 shown in FIG. 6 of the liquid crystal display element 50R for red. Is rewritten with the value of the gamma value table memory 72 corresponding to the amount of light possessed by the image generation unit 71. Next, the value of the gamma value light quantity correction table in the range of region 1 that is the same as the gradation range obtained by rewriting the gamma value light quantity correction table of the liquid crystal display element 50R for red is displayed as an image. The value is rewritten with the value in the gamma value table memory 72 corresponding to the amount of light owned by the generation unit 71. Next, the value of the gamma value light amount correction table in the range of region 1 that is the same as the gradation range obtained by rewriting the gamma value light amount correction table of the liquid crystal display element 50R for red is displayed as an image. The value is rewritten with the value in the gamma value table memory 72 corresponding to the amount of light owned by the generation unit 71.

  When the rewriting of the value of the gamma value light amount correction table in the gradation range having all the constituent colors constituting the color image is completed, the rewriting of the gamma value light amount correction table in the next gradation range is executed.

  That is, among the values of the gamma value light amount correction table stored in the buffer memory 63, first, the values of the gamma value light amount correction table in the gradation range of the region 2 different from the previous point of the red liquid crystal display element 50R are imaged. The value is rewritten with the value in the gamma value table memory 72 corresponding to the amount of light owned by the generation unit 71. Next, image generation is performed for the value of the gamma value light quantity correction table in the range 2 that is the same as the gradation range in which the gamma value light quantity correction table of the red liquid crystal display element 50R of the green liquid crystal display element 50G is rewritten. The value is rewritten with the value in the gamma value table memory 72 corresponding to the amount of light owned by the unit 71. Next, the value of the gamma value light amount correction table in the gradation range of the region 2 that is the same as the gradation range obtained by rewriting the gamma value light amount correction table of the red liquid crystal display element 50R of the blue liquid crystal display element 50B is obtained. The value is rewritten with the value in the gamma value table memory 72 corresponding to the amount of light owned by the image generation unit 71.

  By the above method, the value of the gamma value table memory 72 corresponding to the light amount owned by the image generation unit 71 is set according to the light amount of the liquid crystal display element 50 at the time of image display up to the region 8 that is the entire gradation range. The gamma value light amount correction table is rewritten step by step to compensate for the electro-optical characteristics accompanying the light amount change of the light source 10 of the liquid crystal display device 1.

  According to the above flowchart, when the liquid crystal display device 1 is used, the electro-optical characteristics can be accurately compensated with the change in the light amount of the light source 10 of the liquid crystal display device 1 without visually recognizing image degradation due to coloring. Can do.

  In the present embodiment, an operation for accurately correcting the gamma value with respect to the change with time of the light source 10 of the liquid crystal display device 1 will be described based on the flowchart shown in FIG.

  As shown in FIG. 5, an optical sensor 81 that detects the amount of light from the light source 10 is disposed outside the projection screen area of the liquid crystal display element 50. In the liquid crystal display element 50, there are an image display area for displaying an image, a projection screen area projected onto the screen 200 from the liquid crystal display device 1, and an area outside the projection screen area that is not projected onto the screen 200. . By disposing at this position, it is possible to always obtain light incident on the liquid crystal display device 50 from the light source 10 without blocking the projected image and without projecting the optical sensor on the projection screen. And it is set as the light quantity recognition means 80 which recognizes the change of a light quantity by detecting the output of this optical sensor 81. FIG.

  The light amount recognizing means 80 recognizes that the brightness of the light source 10 of the liquid crystal display device 1 has decreased by the light amount recognizing means 80 from the output of the optical sensor 81, and starts light amount gamma adjustment (Step 1).

  The recognized light quantity is transmitted from the light quantity recognition means 80 to the gamma value light quantity correction function memory 61. For example, when the brightness of the light source 10 decreases by 20%, 0.8 is transmitted as the light amount value to the gamma value light amount correction function memory 61 (Step 2).

  Next, the correction amount of the gamma value corresponding to the light amount value transmitted from the light amount recognition means 80 is calculated from the gamma value light amount correction function memory 61 (Step 3). As a method for calculating the correction amount of the gamma value, it is possible to accurately correct a change in the light amount without increasing the number of memories by obtaining a correction amount corresponding to the light amount from an equation approximated by a function.

  Then, the gamma value correction amount corresponding to the calculated light amount and the gamma value stored in the currently selected gamma value table memory 62 are added together by the gamma value light amount correction calculation circuit 74 (Step 4). The added gamma value is a gamma value suitable for the current amount of light of the liquid crystal display device 1.

  The obtained gamma values are sequentially transmitted to the buffer memory 63 (Step 5).

  Then, the gamma values stored in the buffer memory 63 are sequentially transmitted to the gamma value table memory 72 corresponding to the amount of light in the image generation unit 71 (Step 6).

  Step 3 to Step 6 are repeated until transmission of the gamma value to the gamma value table memory 72 is completed for all the constituent colors and all the gradations of the liquid crystal display device 1 (Step 7).

  According to the above flow chart, when the liquid crystal display device 1 is used, the electro-optical characteristics of the light source 10 of the liquid crystal display device 1 with high-precision brightness change without being visually recognized in real time due to color degradation. Can be compensated.

  In the present embodiment, the operation for accurately correcting the gamma value even when the number of light sources 10 of the liquid crystal display device 1 is changed and the light quantity is changed will be described based on the flowchart shown in FIG. To do.

The liquid crystal display device 1 shown in FIG. 1 is a configuration diagram in the case where one light source 10 is provided. However, it is possible to brighten the liquid crystal display device 1 by arranging a plurality of light sources 10 at present. In such a liquid crystal display device 1, it is possible to use the liquid crystal display device 1 with the brightness required by the user by changing the number of lighting of the light source 10 according to the usage.
On the other hand, by changing the number of lighting of the light source 10, the amount of light incident on the liquid crystal display element 50 is greatly changed.

  The light quantity recognition means 80 recognizes from the light quantity recognition means 80 that the lighting number of the light source 10 of the liquid crystal display device 1 has changed, and starts the light quantity gamma adjustment (Step 1).

  The recognized light quantity is transmitted from the light quantity recognition means 80 to the gamma value light quantity correction function memory 61. For example, when the number of light sources to be lit is changed from two to one, 0.5 is transmitted as the light amount value to the gamma value light amount correction function memory 61 (Step 2).

  Next, the correction amount of the gamma value corresponding to the light amount value transmitted from the light amount recognition means 80 is calculated from the gamma value light amount correction function memory 61 (Step 3). As a method for calculating the correction amount of the gamma value, it is possible to accurately correct a change in the light amount without increasing the number of memories by obtaining a correction amount corresponding to the light amount from an equation approximated by a function.

  Then, the gamma value correction amount corresponding to the calculated light amount and the gamma value stored in the currently selected gamma value table memory 62 are added together by the gamma value light amount correction calculation circuit 74 (Step 4). The added gamma value is a gamma value suitable for the current amount of light of the liquid crystal display device 1.

  The obtained gamma values are sequentially transmitted to the buffer memory 63 (Step 5).

  Then, the gamma values stored in the buffer memory 63 are sequentially transmitted to the gamma value table memory 72 corresponding to the amount of light in the image generation unit 71 (Step 6).

  Step 3 to Step 6 are repeated until transmission of the gamma value to the gamma value table memory 72 is completed for all the constituent colors and all the gradations of the liquid crystal display device 1 (Step 7).

  According to the above flowchart, when the liquid crystal display device 1 is used, the electro-optical characteristics can be compensated for with a change in the brightness of the light source of the liquid crystal display device 1 without being visually recognized in real time. Can do.

  In this embodiment, the operation for correcting the gamma value with high accuracy even when the light amount is changed by arranging a diaphragm between the light source 10 of the liquid crystal display device 1 and the liquid crystal display element 50 is shown in FIG. This will be described based on the flowchart described in FIG.

  In the liquid crystal display device 1 shown in FIG. 2, a diaphragm (not shown) is disposed between the light paths of the light source 10 and the liquid crystal display element 50. By changing the aperture ratio of the diaphragm, the amount of light incident on the liquid crystal display element 50 and the incident angle can be changed. By changing the aperture ratio with this diaphragm, the brightness and contrast of the liquid crystal display device 1 can be changed. In such a liquid crystal display device 1, it is possible to use the liquid crystal display device 1 with the brightness and contrast required by the user by changing the aperture ratio of the diaphragm according to the intended use.

  On the other hand, by changing the aperture ratio of the diaphragm, the amount of light of the light source 10 incident on the liquid crystal display element 50 is greatly changed, so that the electro-optical characteristics of the liquid crystal display element 50 are changed.

  The light quantity recognition means 80 recognizes that the aperture ratio of the diaphragm of the liquid crystal display device 1 has changed by the light quantity recognition means 80 and starts the light quantity gamma adjustment (Step 1).

  The recognized light quantity is transmitted from the light quantity recognition means 80 to the gamma value light quantity correction function memory 61. For example, when the aperture ratio of the aperture is changed from the state where the aperture ratio of the aperture is most opened to the state where the amount of light applied to the liquid crystal display element 50 is halved, 0.5 is used as the light amount value. It transmits to the value light quantity correction function memory 61 (Step 2).

  Next, the correction amount of the gamma value corresponding to the light amount value transmitted from the light amount recognition means 80 is calculated from the gamma value light amount correction function memory 61 (Step 3). As a method for calculating the correction amount of the gamma value, it is possible to accurately correct a change in the light amount without increasing the number of memories by obtaining a correction amount corresponding to the light amount from an equation approximated by a function.

  Then, the gamma value correction amount corresponding to the calculated light amount and the gamma value stored in the currently selected gamma value table memory 62 are added together by the gamma value light amount correction calculation circuit 74 (Step 4). The added gamma value is a gamma value suitable for the current amount of light of the liquid crystal display device 1.

  The obtained gamma values are sequentially transmitted to the buffer memory 63 (Step 5).

  Then, the gamma values stored in the buffer memory 63 are sequentially transmitted to the gamma value table memory 72 corresponding to the amount of light in the image generation unit 71 (Step 6).

  Step 3 to Step 6 are repeated until transmission of the gamma value to the gamma value table memory 72 is completed for all the constituent colors and all the gradations of the liquid crystal display device 1 (Step 7).

  According to the above flowchart, when the liquid crystal display device 1 is used, the electro-optical characteristics can be compensated for with a change in the brightness of the light source of the liquid crystal display device 1 without being visually recognized in real time. Can do.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 10 Lamp 20 Illumination optical system 30 Color separation synthetic | combination optical system 40 Projection lens optical system 50G G liquid crystal display element 50R R liquid crystal display element 50B B liquid crystal display element 60 Memory | storage part 61 Gamma value light quantity correction function memory 62 Gamma value table memory 63 Buffer memory 70 Control unit 71 Image generation unit 72 Gamma value table memory 73 according to the light quantity DA converter 74 Gamma value light quantity correction calculation circuit 80 Light quantity recognition means 81 Optical sensor

Claims (9)

A liquid crystal display device for displaying an image,
A light source, a liquid crystal display element that modulates light from the light source and generates an image, a control unit that controls a signal applied to the liquid crystal display element, a storage unit that stores a gamma value, and a liquid crystal display element A light amount recognizing unit for recognizing a change in light amount from the irradiated light source, and a gamma value correcting unit for correcting the gamma value in the storage unit based on a result of the light amount detecting unit; Liquid crystal display device. 2. The liquid crystal display device according to claim 1, further comprising means for recognizing that the output of the light source has been changed as the light quantity recognizing means. The liquid crystal display device according to claim 1, wherein the light amount recognition unit recognizes a light amount change based on an output of an optical sensor that detects a light amount from the light source irradiated on the liquid crystal display element. The light quantity recognizing means includes means for recognizing that the light quantity from the light source is changed by shielding a part of the optical path between the light source and the optical path of the liquid crystal display element. Item 2. A liquid crystal display device according to item 1. The liquid crystal display device according to claim 1, wherein the light source includes at least two light sources. 6. The liquid crystal display device according to claim 5, further comprising means for detecting that at least one of the light sources is turned off as the light quantity recognizing means. 7. The output value of the light quantity recognition means is transmitted to the gamma value light quantity correction function memory as the same for all the constituent colors of the liquid crystal display device 1. A liquid crystal display device according to 1. 8. The liquid crystal display device according to claim 1, wherein the amount of change in the amount of light from the light source has a change of at least twice. The liquid crystal display device according to any one of claims 1 to 8, wherein the liquid crystal display device is a projection type liquid crystal display device.