JP4742693B2 - Image display device adjustment device, image display device, and image display device adjustment method - Google Patents

Description

The present invention relates to an image display device adjustment device, an image display device, and an image display device adjustment method.

 As one form of an image display device, a liquid crystal projector is known that enlarges and projects a display image emitted from an optical system using a liquid crystal light valve onto a screen through a projection lens. Such a liquid crystal projector has the following problems.

(1) A sufficient contrast cannot be obtained due to light leakage and stray light generated by various optical elements constituting the optical system. For this reason, the displayable gradation range (dynamic range) is narrow, and the quality and power of the displayed image are inferior compared with an existing television using a cathode ray tube (CRT).
(2) Even if an attempt is made to improve the quality of a display image by various image signal processing, the dynamic range is fixed, so that a sufficient effect cannot be exhibited.

As a solution to the problem of such a liquid crystal projector, that is, a method of extending the dynamic range, it is conceivable to change the light amount of the light source incident on the light modulator (light valve) according to the image signal. The simplest way to achieve this is to change the light output intensity of the light source lamp. For example, Patent Document 1 below discloses a technique for controlling output light from a light source lamp in accordance with an image signal in a liquid crystal projector.
JP-A-5-66501

   However, high-pressure mercury lamps are mainly used as light source lamps for liquid crystal projectors, but it is extremely difficult to control the light output intensity of the high-pressure mercury lamp. For this reason, there is a need for a method of changing the amount of light incident on the light modulation means in accordance with the video signal without changing the light output intensity itself of the light source lamp. In addition to the above-mentioned problems, the light output intensity of the light source lamp is fixed. For example, in a dark viewing environment, the display image becomes too bright, or the projection screen size depends on the projection distance and zooming of the projection lens. There is also a problem in that the brightness of the display image changes in accordance with the change of.

   In order to solve such problems, in recent years, a structure in which a light source lamp of a liquid crystal projector is combined with a light control plate (light control element) for light control has been proposed. Specifically, a light shielding plate is arranged on the optical axis of the light emitted from the light source lamp, and this is rotated around a rotation axis parallel to the main surface to partially shield the light source light. Dimming is performed. By adjusting the light source light in accordance with the image signal with such a light control element, it is possible to obtain light with brightness according to the display image even when the light output intensity of the light source lamp remains constant. Can contribute to the expansion of the dynamic range. Similarly, it is possible to obtain light having a brightness according to the projection magnification ratio, the brightness condition in the usage environment, or the user's preference.

 By the way, when performing such dimming processing, it is necessary to keep the brightness change per unit time within a certain range. This is because if the brightness change is too early, it is recognized by the user as flickering of the display image, and if it is too late, the impression of the original video is impaired. Therefore, it is necessary to perform dimming processing accurately in accordance with the image. For that purpose, the optical characteristics of the dimming element (the amount of change in the light source light with respect to the control amount of the dimming element) is confirmed in advance, and the optical characteristics Therefore, it is necessary to determine the control amount of the light control element suitable for the above. However, if the optical characteristics of one dimming element are measured and other dimming elements are controlled by the control amount of the dimming element determined based on the optical characteristics, the optical characteristics of the dimming element may vary depending on the individual characteristics. Therefore, accurate dimming processing cannot be performed, and the above-described flickering of the display image may occur.

   The present invention has been made in view of the above circumstances, and it is an object of the present invention to reduce the influence of individual differences among dimming elements and to perform stable dimming processing.

In order to solve the above-described problems, an adjustment device for an image display device according to the present invention includes a light control unit that performs light control of illumination light emitted from a light source, and a light control unit that controls the light control unit. An adjustment device for determining a dimming control parameter for controlling the dimming means of the image display device comprising: an interface for connecting to the image display device; and a light amount detection for detecting the light amount of the illumination light And a dimming control parameter for optical characteristic measurement for controlling the dimming means, and a light amount of the illumination light detected according to the dimming control parameter in the dimming control parameter adjustment mode. ginseng showing a correspondence relationship between image parameter determines the optical characteristics, based on the optical properties characterizing the brightness of the dimming control parameter and the display image of said light control means on the basis of the And a dimming control parameter adjusting means for creating data, dimming control parameter adjusting means, the of the image display device the reference data which has been subjected to averaging processing on the dimming control parameter via the interface It is stored in the dimming control means.
In order to solve the above-described problems, an adjustment device for an image display device according to the present invention includes a light control unit that performs light control of illumination light emitted from a light source, and a light control unit that controls the light control unit. An adjustment device for determining a dimming control parameter for controlling the dimming means of the image display device comprising: an interface for connecting to the image display device; and a light amount detection for detecting the light amount of the illumination light And a dimming control parameter for optical characteristic measurement for controlling the dimming means, and a light amount of the illumination light detected according to the dimming control parameter in the dimming control parameter adjustment mode. ginseng showing a correspondence relationship between image parameter determines the optical characteristics, based on the optical properties characterizing the brightness of the dimming control parameter and the display image of said light control means on the basis of the A dimming control parameter adjusting unit for creating data, and the dimming control parameter adjusting unit compares the dimming control parameter with a predetermined limit value, and there is a dimming control parameter exceeding the limit value. In this case, the reference data obtained by converting the dimming control parameter into the limit value is stored in the dimming control unit of the image display device via the interface.
In order to solve the above-described problems, an adjustment device for an image display device according to the present invention includes a light control unit that performs light control of illumination light emitted from a light source, and a light control unit that controls the light control unit. An adjustment device for determining a dimming control parameter for controlling the dimming means of the image display device comprising: an interface for connecting to the image display device; and a light amount detection for detecting the light amount of the illumination light And a dimming control parameter for optical characteristic measurement for controlling the dimming means, and a light amount of the illumination light detected according to the dimming control parameter in the dimming control parameter adjustment mode. Based on the optical characteristics of the light control means, and based on the optical characteristics, a light control control parameter having a constant value such that image flicker is not recognized in the entire control range of the light control means. Determine the meter, characterized in that it and a dimming control parameter adjusting means for storing the dimming control means for dimming control parameter having a constant value said determined via the interface the image display device.
In order to solve the above problems, an adjustment method for an image display device according to the present invention includes a light control unit that performs light control of illumination light emitted from a light source, and a light control unit that controls the light control unit. An adjustment method for determining a dimming control parameter for controlling the dimming means of an image display apparatus comprising: a dimming control parameter for measuring optical characteristics and controlling the dimming means. A first step of detecting a light amount of the illumination light according to the light control parameter; and a second step of determining an optical characteristic of the light control means based on the light amount of the illumination light detected according to the light control parameter A third step of creating reference data indicating a correspondence relationship between the step, the dimming control parameter and the image parameter characterizing the brightness of the display image based on the optical characteristics, and the reference data Wherein a fourth step of applying an averaging process to Murrell the dimming control parameter, and a fifth step of storing the reference data after said fourth step to said dimming control means of the image display device, to have a And
In order to solve the above problems, an adjustment method for an image display device according to the present invention includes a light control unit that performs light control of illumination light emitted from a light source, and a light control unit that controls the light control unit. An adjustment method for determining a dimming control parameter for controlling the dimming means of an image display apparatus comprising: a dimming control parameter for measuring optical characteristics and controlling the dimming means. A first step of detecting a light amount of the illumination light according to the light control parameter; and a second step of determining an optical characteristic of the light control means based on the light amount of the illumination light detected according to the light control parameter A third step of creating reference data indicating a correspondence relationship between the step, the dimming control parameter and the image parameter characterizing the brightness of the display image based on the optical characteristics, and the reference data A dimming control parameter to be compared with a predetermined limit value, and if there is a dimming control parameter exceeding the limit value, a fourth step of converting the dimming control parameter into the limit value; And a fifth step of storing the reference data after the four steps in the dimming control means of the image display device.
In order to solve the above problems, an adjustment method for an image display device according to the present invention includes a light control unit that performs light control of illumination light emitted from a light source, and a light control unit that controls the light control unit. An adjustment method for determining a dimming control parameter for controlling the dimming means of an image display apparatus comprising: a dimming control parameter for measuring optical characteristics and controlling the dimming means. A first step of detecting a light amount of the illumination light according to the light control parameter; and a second step of determining an optical characteristic of the light control means based on the light amount of the illumination light detected according to the light control parameter And a third step of determining a constant light control parameter so that image flicker is not recognized in the entire control range of the light control means based on the optical characteristics, and the third step. A fourth step of the dimming control parameter of said predetermined values obtained are stored in the dimming control section of the image display apparatus, characterized by having a.
In order to solve the above-described problems, the present invention provides an image display apparatus that adjusts the brightness of a display image by dimming processing of illumination light emitted from a light source as a solution means related to the image display apparatus. A light control means for performing the light control, a light quantity detection means for detecting the light quantity of the illumination light, and determining the optical characteristics of the light control means based on the light quantity detected by the light quantity detection means. A dimming control parameter adjusting unit that determines a dimming control parameter for controlling the dimming unit based on the image parameter that characterizes the brightness of the display image at predetermined time intervals from the image signal of the display image; The image parameter extracting means to extract, and the light control control parameter adjusting means determined based on the image parameter extracted by the image parameter extracting means It determines a dimming control parameter according to the light control process from light control parameter comprises a dimming control section for controlling said light control means based on the light control parameter, to adopt a means of.
According to the present invention, the light control parameter for controlling the light control means is determined based on the optical characteristics of the light control means (light control element) provided in the image display device. Therefore, it is possible to perform stable dimming processing without being affected by individual differences of dimming elements.

In the present invention, it is preferable that the light amount detection means detects the brightness of an image displayed on the projection screen as the amount of illumination light.
According to the present invention, the amount of illumination light in a state close to the final viewing environment can be detected, and the amount of illumination light with high reproducibility can be detected.

In the present invention, it is preferable to display an all-white image when detecting the amount of illumination light.
According to the present invention, by displaying the all white image on the projection screen, it is possible to reduce the influence of disturbance such as noise and external light, and to increase the detection accuracy of the illumination light quantity.

In the present invention, it is preferable that the light amount detection means is disposed outside the optical path of the internal illumination light and detects the light amount of the internal reflection light of the illumination light.
According to the present invention, the amount of illumination light can be detected by detecting the internally reflected light without blocking the projection light necessary for image display.

In the present invention, it is preferable to display an all-black image when detecting the amount of the internally reflected light.
According to the present invention, the accuracy of detecting internal reflection light can be increased.

In the present invention, it is preferable that a look-up table indicating a correspondence relationship between the dimming control parameter and the image parameter is created as the reference data .
According to the present invention, fine and precise light control can be performed.

In the present invention, it is preferable that the look-up table is determined so as to match the γ characteristic.
According to the present invention, it is possible to perform image display consistent with the γ characteristic of the image display device.

In the present invention, it is preferable that the look-up table is determined so as to match a luminance value constituting the image.
According to the present invention, for example, when image processing inside the image display apparatus is performed in the YCC color space, an image such as decompression processing is used by using a look-up table combined with a luminance value (Y value). It is possible to display an image that is consistent with the processing.

On the other hand, in the present invention, as a solution means related to the adjustment device of the image display device, an image display including a light control device for adjusting the illumination light emitted from the light source and a light control device for controlling the light control device. a regulating device for determining the dimming control parameter for controlling said light control means of the device, an interface for connecting to the image display device, a light quantity detecting means for detecting the amount of the illumination light, tone At the time of the light control parameter adjustment mode, the light control parameter for measuring the optical characteristics for controlling the light control means is output, and the light control parameter based on the amount of the illumination light detected according to the light control parameter determines the optical characteristics of the light control means, the light control parameter and the image parameter corresponding relationship created dimming control reference data indicating the parameters based on the optical properties And an adjustment means, the dimming control parameter adjusting means employs the called, is stored in the dimming control means via said interface said reference data.
According to the present invention, it is not necessary to provide a light amount detection unit and a dimming control parameter adjustment unit inside the image display device, and the dimming control parameter is determined according to the optical characteristics of the dimming unit included in each image display device. Therefore, stable light control processing can be performed without being affected by individual differences of light control elements.

In the present invention, it is preferable that the light amount detection means detects the brightness of an image displayed on the projection screen as the amount of illumination light.
According to the present invention, the amount of illumination light in a state close to the final viewing environment can be detected, and the amount of illumination light with high reproducibility can be detected.

In the present invention, it is preferable to display an all-white image when detecting the amount of illumination light.
According to the present invention, by displaying the all white image on the projection screen, it is possible to reduce the influence of disturbance such as noise and external light, and to increase the detection accuracy of the illumination light quantity.

In the present invention, it is preferable that the light amount detection unit is disposed outside the optical path of the illumination light inside the image display device and detects the light amount of the internal reflection light of the illumination light.
According to the present invention, the amount of illumination light can be detected by detecting the internally reflected light without blocking the projection light necessary for image display.

In the present invention, it is preferable to display an all black image when detecting the amount of the internally reflected light.
According to the present invention, the accuracy of detecting internal reflection light can be increased.

In the present invention, it is preferable that the dimming control parameter includes a look-up table.
According to the present invention, fine and precise light control can be performed.

In the present invention, it is preferable that the look-up table is determined so as to match a γ characteristic of the image display device.
According to the present invention, it is possible to perform image display consistent with the γ characteristic of the image display device.

In the present invention, it is preferable that the look-up table is determined so as to match a luminance value constituting the image.
According to the present invention, for example, when image processing inside the image display apparatus is performed in the YCC color space, an image such as decompression processing is used by using a look-up table combined with a luminance value (Y value). It is possible to display an image that is consistent with the processing.

In the present invention, it is preferable to perform an averaging process on the look-up table, that is, the dimming control parameter.
According to the present invention, it is possible to reduce the dimming control parameter that changes greatly with respect to the adjacent dimming control parameter, and therefore it is possible to reduce the flickering of the image due to the individual difference of the dimming elements. Therefore, by expanding the look-up table averaged in this way to other image display devices, it is possible to improve the production efficiency and reduce the influence of individual differences of the light control elements, and perform stable light control processing. It is possible.

In the present invention, the look-up table, that is, the dimming control parameter is compared with a predetermined limit value, and if there is a dimming control parameter exceeding the limit value, the dimming control parameter is It is preferable to convert the limit value.
According to the present invention, it is possible to suppress a large change in the dimming control parameter by reducing the dimming control parameter within the limit value, and to reduce image flicker due to individual differences of the dimming elements. . Therefore, by developing the look-up table readjusted in this way to other image display devices, it is possible to improve the production efficiency and reduce the influence of individual differences of the light control elements, and perform stable light control processing. Is possible.

In the present invention, it is preferable that the dimming control parameter adjusting unit determines a dimming control parameter having a constant value so that image flicker is not recognized in the entire control range of the dimming unit.
According to this invention, regardless of the image parameter, a constant value of the dimming control parameter is set so that image flicker is not recognized, and the dimming element is controlled by the dimming control parameter. It is possible to reduce image flicker due to individual differences. Therefore, by developing the dimming control parameters set in this way to other image display devices, it is possible to improve the production efficiency and reduce the influence of individual differences of the dimming elements, and to perform stable dimming processing. It is.

According to the present invention, there is provided an image display device including a light control unit that performs light control of illumination light emitted from a light source and a light control unit that controls the light control unit as a solution unit related to the image display device. The dimming control means employs means for controlling the dimming means using the reference data created by the adjusting device of the image display device.
According to the present invention, the dimming control parameter is determined for one typical image display device using the adjustment device for the image display device described above, and the dimming control parameter thus determined is determined as another image display device. Therefore, the production efficiency can be improved and the influence of individual differences of the light control elements can be reduced, and stable light control processing can be performed.

In the present invention, it is preferable that the above-described image display device includes an expansion processing unit that performs an expansion process according to a display image.
According to the present invention, it is possible to make maximum use of the dynamic range of the image display device by image processing based on linkage between expansion processing and light control processing.

Furthermore, the present invention provides an image display method for adjusting the brightness of a display image by dimming processing of illumination light emitted from a light source by a predetermined dimming means as a solving means related to the image display method, and measuring optical characteristics A first step of controlling the dimming means using a dimming control parameter for use and detecting a light amount of the illumination light according to the dimming control parameter, and the detection detected according to the dimming control parameter The second step of determining the optical characteristics of the light control means based on the amount of illumination light, and the correspondence relationship between the light control parameters and the image parameters characterizing the brightness of the display image based on the optical characteristics a third step of creating a reference data indicating a fourth step of extracting the image parameters from an image signal of a display image at every predetermined time interval, the third step And a dimming control parameter determined in the fifth step based on the reference data created in step 5 to determine the dimming control parameter corresponding to the image parameter extracted in the fourth step. And a sixth step of controlling the light control means based on the above .
According to the present invention, the light control parameter for controlling the light control means is determined based on the optical characteristics of the light control means (light control element) provided in the image display device. Therefore, it is possible to perform stable dimming processing without being affected by individual differences of dimming elements.

Further, in the present invention, as a solving means related to the adjustment method of the image display device, an image display including a dimming means for dimming illumination light emitted from the light source and a dimming control means for controlling the dimming means. An adjustment method for determining a dimming control parameter for controlling the dimming means of an apparatus, wherein the dimming control parameter for optical characteristic measurement is used to control the dimming means and to the dimming control parameter A first step of detecting a light amount of the illumination light according to the second step, a second step of determining an optical characteristic of the light control means based on the light amount of the illumination light detected according to the light control parameter; The third step of creating reference data indicating the correspondence between the dimming control parameter and the image parameter characterizing the brightness of the display image based on the optical characteristics, and the third step Adopting means of the reference data having a fourth step of storing the dimming control unit.
According to the present invention, it is not necessary to provide a light amount detection unit and a dimming control parameter adjustment unit inside the image display device, and the dimming control parameter is determined in accordance with the optical characteristics of the dimming unit included in each image display device. Therefore, stable light control processing can be performed without being affected by individual differences of light control elements.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, a description will be given using a three-plate liquid crystal projector provided with a liquid crystal light valve for each of different colors of RGB as an example of an image display device.
FIG. 1 is a schematic configuration diagram illustrating an example of a liquid crystal projector. As shown in FIG. 1, this liquid crystal projector includes a light source 510, a light control element 6, fly-eye lenses 21, 22, dichroic mirrors 513, 514, reflection mirrors 515, 516, 517, relay lenses 518, 519, 520, red. The liquid crystal light valve 522 for light, the liquid crystal light valve 523 for green light, the liquid crystal light valve 524 for blue light, the cross dichroic prism 525, the projection lens system 526, and the light amount detection sensor 1 are configured.

   The light source 510 includes a lamp 511 such as an extra-high pressure mercury lamp and a reflector 512 that reflects light from the lamp 511. Between the light source 510 and the dichroic mirror 513, fly-eye lenses 21 and 22 for making the illuminance distribution of the emitted light from the light source 510 uniform, and the light control element 6 for adjusting the amount of the emitted light are arranged. Yes. The light control element 6 is composed of a first light shielding plate 6a and a second light shielding plate 6b, and the first light shielding plate 6a and the second light shielding plate 6b are rotated by a stepping motor (not shown) to reduce the optical path area of the emitted light. Adjust the amount of light by changing.

 The dichroic mirror 513 transmits red light of white light incident from the light source 510 to the reflection mirror 517 and reflects blue light and green light to the dichroic mirror 514. The reflection mirror 517 reflects the red light incident from the dichroic mirror 513 to the liquid crystal light valve 522 for red light.

   On the other hand, the dichroic mirror 514 reflects green light to the liquid crystal light valve 523 for green light out of the blue light and green light incident from the dichroic mirror 513 and transmits the blue light to the relay lens 518. The blue light is incident on the blue light liquid crystal light valve 524 via a relay system 521 including a relay lens 518, a reflection mirror 515, a relay lens 519, a reflection mirror 516, and a relay lens 520.

   The liquid crystal light valve for red light 522, the liquid crystal light valve for green light 523, and the liquid crystal light valve for blue light 524 modulate the three color lights (red light, green light, blue light) incident on each, and cross dichroic prisms. The light is emitted to 525. The cross dichroic prism 525 includes four right-angle prisms bonded together, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in a cross shape on the inner surface thereof. These dielectric multilayer films combine the three color lights to form light representing a color image. The synthesized light is projected on the screen 527 by the projection lens system 526 which is a projection optical system, and the image is enlarged and displayed. The light amount detection sensor 1 is installed at the center of the screen 527, detects the light amount of light (projection light) projected on the screen 527, and outputs a detection signal indicating the light amount to the first A / D converter 2 (FIG. 1). (Not shown). The first A / D converter 2 will be described below.

   FIG. 2 is a block diagram showing the configuration of the drive circuit of the present liquid crystal projector configured as described above. As shown in this figure, the drive circuit of the present liquid crystal projector includes a light amount detection sensor 1, a first A / D converter 2, a dimming control parameter adjustment unit 3, a dimming control unit 4, a dimming element driver 5, a dimming element driver 5, and a dimming element driver 5. Optical element 6, second A / D converter 7, image parameter extraction unit 8, decompression processing unit 9, D / A converter 10, light valve driver 11, red light liquid crystal light valve 522, green light liquid crystal light valve 523 And a liquid crystal light valve 524 for blue light.

 This liquid crystal projector has two operation modes (a dimming control parameter adjustment mode and a normal display mode). Of these two operation modes, the dimming control parameter adjustment mode is an optical characteristic of the dimming element 6 (more specifically, the number of steps of the stepping motor that drives the first light shielding plate 6a and the second light shielding plate 6b). In this mode, a light control parameter that is optimal for driving the light control element 6 is adjusted based on the optical characteristics. Here, the dimming control parameter is the number of steps of the stepping motor that drives the dimming element 6, that is, the first light shielding plate 6a and the second light shielding plate 6b. On the other hand, in the normal display mode, a desired image (image signal) supplied from an external image supply device is expanded, and light control is performed using the light control parameter determined in the light control parameter adjustment mode. In this mode, processing is performed and an image is displayed on the screen 527.

  As described with reference to FIG. 1, the light quantity detection sensor 1 detects the projection light quantity projected on the screen 527, and outputs a detection signal indicating the projection light quantity to the first A / D converter 2. The second A / D converter 2 performs A / D conversion on the detection signal (analog signal) input from the light amount detection sensor 1 and outputs it to the dimming control parameter adjustment unit 3 as a digital detection signal. The dimming control parameter adjustment unit 3 outputs the dimming control parameter for measuring the optical characteristics of the dimming element 6 to the dimming control unit 4, and the dimming element 6 is controlled by the dimming control parameter for measuring the optical characteristics. The optical characteristics of the light control element 6 are determined based on the projection light quantity (digital detection signal) when driven, and the light control parameters for the normal display mode and the brightness of the image are characterized based on the optical characteristics. A LUT (Look Up Table) indicating the correspondence with the image parameter is created and output to the light control unit 4. The light quantity detection sensor 1, the first A / D converter 2, and the dimming control parameter adjustment unit 3 are in an active state only in the dimming control parameter adjustment mode.

  In the dimming control parameter adjustment mode, the dimming control unit 4 outputs the dimming control parameters for measuring the optical characteristics input from the dimming control parameter adjusting unit 3 to the dimming element driver 5, and the dimming control. The LUT created by the parameter adjustment unit 3 is stored in the internal memory. Further, in the normal display mode, the dimming control unit 4 determines the dimming control parameter based on the image parameter input from the image parameter extracting unit 8 and the LUT, and the dimming control parameter is determined by the dimming element driver. 5 is output.

 The dimming element driver 5 is based on the dimming control parameter for measuring the optical characteristics input from the dimming control unit 4 or the dimming control parameter determined based on the LUT, that is, the dimming element 6, that is, the stepping. A drive signal for driving the motor is generated, and the drive signal is output to the light control element 6. The light control element 6 is driven based on the drive signal, thereby changing the amount of light emitted from the light source 510.

  The second A / D converter 7 A / D converts an image signal (analog signal) supplied from an external image supply device, and outputs it to the image parameter extraction unit 8 as a digital image signal. The image signal which is an analog signal has the magnitude of the voltage value as the brightness information of the image, but has the gradation value corresponding to the voltage value as the brightness information by being converted into the digital image signal. become. The image supply device is, for example, a PC (Personal Computer), reproduces an image stored on a recording medium such as a hard disk or a DVD (Digital Versatile Disk), and a synchronization signal (see FIG. (Not shown) is output to the liquid crystal projector.

  In the normal display mode, the image parameter extraction unit 8 performs an image parameter (gradation value) characterizing the brightness of the display image from the digital image signal input from the second A / D converter 7 by a predetermined extraction process. The extracted image parameter and the digital image signal are output to the expansion processing unit 9 and the image parameter is output to the dimming control unit 4. The image parameter extraction unit 8 outputs the digital image signal to the expansion processing unit 9 without performing the image parameter extraction process in the dimming control parameter adjustment mode. In the normal display mode, the decompression processing unit 9 determines the decompression control parameter based on the image parameter, performs the decompression process of the gradation value constituting the digital image signal based on the decompression control parameter, and performs the decompression process after the decompression process. The digital image signal is output to the D / A converter 10. Further, the expansion processing unit 9 outputs the digital image signal to the D / A converter 10 without performing the expansion processing in the dimming control parameter adjustment mode. A method for determining such an extension control parameter will be described later.

 The D / A converter 10 D / A converts the digital image signal input from the expansion processing unit 9 and outputs the analog image signal to the light valve driver 11. The light valve driver 11 drives to drive the red light liquid crystal light valve 522, the green light liquid crystal light valve 523, and the blue light liquid crystal light valve 524 based on the analog image signal input from the D / A converter 10. A signal is generated and output to each liquid crystal light valve. As described with reference to FIG. 1, the liquid crystal light valve for red light 522, the liquid crystal light valve for green light 523, and the liquid crystal light valve for blue light 524 are driven by the drive signal and are incident on the three color lights (red Light, green light, blue light).

Next, operations of the light control parameter adjustment mode and the normal display mode in the liquid crystal projector configured as described above will be described.
[Dimming control parameter adjustment mode]
FIG. 3 is a flowchart showing a dimming control parameter determination (LUT creation) processing procedure in the dimming control parameter adjustment mode. First, switching to the dimming control parameter adjustment mode is performed (step S1). Such mode switching is performed, for example, by providing a mode switching switch or the like in the liquid crystal projector and operating the mode switching switch.

 Next, an all white pattern image is supplied to the present liquid crystal projector as an adjustment image from the image supply device (step S2). Thus, by displaying the all white pattern image on the screen 527, the influence of disturbance such as noise and external light can be reduced, and the detection accuracy of the projection light quantity can be increased. In the present embodiment, a liquid crystal projector that performs 256 gradation display from 0 (black) to 255 (white) gradation is assumed.

 The all white pattern image signal input from the external image supply device is converted into a digital image signal by the second A / D converter 7 and input to the image parameter extraction unit 8. As described above, this digital image signal has, as the brightness information of the image, a gradation value corresponding to RGB of each pixel which is a constituent unit of the image (here, since it is an all-white pattern image, all pixels have 255 gradations). It is what you have. The image parameter extraction unit 8 outputs the digital image signal to the expansion processing unit 9 without performing image parameter extraction processing. Similarly, the expansion processing unit 9 outputs the digital image signal to the D / A converter 10 without performing expansion processing. That is, an all white pattern image is displayed on the screen 527.

 Subsequently, the dimming control parameter adjusting unit 3 outputs a dimming control parameter for measuring optical characteristics to the dimming control unit 4 (step S3). Since the dimming control parameter is the number of steps of the stepping motor that drives the dimming element 6, that is, the first light shielding plate 6a and the second light shielding plate 6b, 0 to the maximum step number (max) is the stepping motor (first step). Assuming the rotation range of the light shielding plate 6a and the second light shielding plate 6b), the dimming control parameter adjusting unit 3 sets the dimming control parameter so that it increases step by step from 0 to the maximum number of steps. Output to the control unit 4.

 The dimming element driver 5 generates a drive signal for driving the dimming element 6, that is, the stepping motor, in accordance with the dimming control parameter set as described above, and outputs the drive signal to the stepping motor. That is, the stepping motor rotates step by step from 0 to max steps. At this time, the amount of light projected on the screen 527 is detected by the light amount detection sensor 1 in synchronization with the operation of the stepping motor (step S4). The relationship between the number of steps of the stepping motor thus obtained (dimming control parameter) and the projection light quantity is the optical characteristic of the dimming element 6. An example of the optical characteristics of the light control element 6 is shown in FIG. As shown in FIG. 4, in this embodiment, a case is assumed in which the maximum projection light amount is 0 steps and the minimum projection light amount is max steps.

  Then, the dimming control parameter adjustment unit 3 creates an LUT used in the normal display mode based on the optical characteristics of the dimming element 6 obtained as described above (step S5). This LUT is created so as to be consistent with the γ characteristic of the liquid crystal projector. For example, a γ characteristic with a γ value = 2.2 as shown in FIG. 5 is assumed. When the image parameter (gradation value) that characterizes the brightness of the image input from the image supply device is 128 gradations, the 128 gradations are converted into the maximum gradation value that can be output, that is, 255 gradations. Thus, it is necessary to reduce the amount of light emitted from the light source 510 to a brightness of 128 gradations.

As can be seen from FIG. 5, when the output luminance at 255 gradation is 100%, the output luminance at 128 gradation is about 20%. That is, it is necessary to reduce the amount of light emitted from the light source 510 to 20%. Then, the optical characteristics of FIG. 4, the emission light intensity of the light source 510, that is, to reduce the projection amount to 20 percent, it can be seen that may be determined number of steps of the stepping motor (dimming control parameter) to X _128. In this way, the LUT is created by determining the dimming control parameter for the image parameter based on the γ characteristic and the optical characteristic of the dimmer 6. FIG. 6 is an example of the LUT created as described above. The dimming control parameter adjustment unit 3 outputs the LUT created in this way to the dimming control unit 4 and stores it (step S6).

 This is the end of the dimming control parameter adjustment mode. The LUT is created so that the optical characteristic of the light control element 6 and the γ characteristic of the liquid crystal projector can be matched. For example, when the image signal is image-processed in the YCC color space, the LUT is bright. The LUT may be created so as to be consistent with the luminance value (Y value) representing the height.

[Normal display mode]
Next, the normal display mode will be described.
When the dimming control parameter adjustment mode ends, the mode switch is operated to switch to the normal display mode. Alternatively, the display mode may be automatically switched to the normal display mode when the dimming control parameter adjustment mode ends.

 Then, a desired image (image signal) is input to the liquid crystal projector from an external image supply device. The image signal is converted into a digital image signal by the second A / D converter 7 and input to the image parameter extraction unit 8. The image parameter extraction unit 8 creates brightness information included in one arbitrary frame from the digital image signal, that is, the appearance number distribution (histogram) of gradation values. For example, assume that the histogram of gradation values included in one frame is as shown in FIG. In this case, as shown in FIG. 7A, the maximum gradation value in the one frame is 150 gradations. The image parameter extraction unit 8 determines 150 gradations, which is the maximum gradation value, as image parameters based on the histogram.

 When the image parameter extraction unit 8 extracts and determines the 150 gradations as image parameters, the image parameter extraction unit 8 outputs the image parameters to the expansion processing unit 9 and the dimming control unit 4, and outputs a digital image signal to the expansion processing unit 9. . The expansion processing unit 9 determines an expansion control parameter based on the image parameter. In other words, in order to make maximum use of the dynamic range, the expansion control parameter is determined as expansion coefficient G = maximum tone value that can be output / image parameter = 255/150 = 1.7. By determining the expansion control parameter (expansion coefficient G) in this way, as shown in FIG. 7B, the input gradation value (the gradation value included in the digital image signal) is multiplied by the expansion control parameter. Can be expanded linearly up to the maximum gradation value that can be output, and the dynamic range can be maximized. In FIG. 7B, the output gradation value is a gradation value after the input gradation value is expanded.

 The decompressed digital image signal is output to the D / A converter 10 and converted to an analog image signal, and then output to the light valve driver 11. The light valve driver 11 generates drive signals for driving the red light liquid crystal light valve 522, the green light liquid crystal light valve 523, and the blue light liquid crystal light valve 524 based on the analog image signal. Output to the valve. Each liquid crystal light valve is driven by the drive signal, and the three color lights (red light, green light, and blue light) incident thereon are modulated, and an image is displayed on the screen 527.

 On the other hand, when the image parameter is input from the image parameter extraction unit 8, the dimming control unit 4 determines the dimming control parameter based on the LUT created in the dimming control parameter adjustment mode, and the dimming control parameter Is output to the dimming element driver 5. When the γ value = 2.2, the 150th gradation is about 30% brighter than the 255th gradation, and therefore the dimming control parameter having a value for reducing the amount of light emitted from the light source 510 to about 30% is determined. . The dimming element driver 5 generates a drive signal based on the dimming control parameter to drive the dimming element 6, and as a result, the amount of light emitted from the light source 510 is reduced to 30%. By such dimming processing, the amount of light emitted from the light source 510 is dimmed according to the image signal, thereby obtaining light with brightness according to the display image even when the light output intensity of the light source 510 remains constant. Can contribute to the expansion of the dynamic range of the liquid crystal projector.

 As described above, according to the present liquid crystal projector, since the dimming control parameter is determined in accordance with the optical characteristics of the individual dimming elements 6, the influence of individual differences of the dimming elements 6 can be reduced, and stable dimming can be achieved. Processing can be performed. However, on the other hand, as described above, when each of the liquid crystal projectors is adjusted for the dimming control parameter, an adverse effect occurs. For example, if the user adjusts the dimming control parameter when purchasing the liquid crystal projector, the user is forced to make efforts. Although a method of adjusting the dimming control parameter in the production process is also conceivable, there is a problem that the production efficiency is extremely deteriorated because it is necessary to process an enormous number of units.

 In order to solve such a problem, it is most efficient to determine a dimming control parameter using a typical one in advance and deploy it to other liquid crystal projectors in the production process. However, in this method, the influence due to individual differences of the light control elements 6 becomes large, and there is a possibility that stable light control processing cannot be performed. For example, as shown in FIG. 6, although “2” originally needs to be selected as the dimming control parameter, “20” is substantially selected due to individual differences of the dimming element 6. If it does, it will be recognized as flickering on the screen. Therefore, a method for improving the production efficiency as described above and reducing the influence of individual differences of the light control elements 6 and performing stable light control processing will be described below.

(1) Method of Averaging Processing on LUT Created in Dimming Control Parameter Adjustment Mode First, a dimming control parameter, that is, the LUT shown in FIG. Then, an averaging process is performed on the dimming control parameters of the LUT thus created. Specifically, as shown in FIG. 8A, the dimming control parameters corresponding to the image parameter “1” are “12” and the dimming control parameters “2” and “10” adjacent thereto. Convert to average value. That is, (12 + 2 + 10) / 3≈8. Similarly, the light control parameter corresponding to the image parameter “2” is set to (10 + 12 + 7) / 3≈10. Similarly, the LUT is readjusted by converting to a new dimming control parameter by averaging processing.

  In this way, by performing the averaging process, it is possible to reduce the dimming control parameter that greatly changes with respect to the adjacent dimming control parameter, and thus reduce flickering of the screen due to individual differences of the dimming elements 6. Is possible. Therefore, by deploying the LUT readjusted in this way to other liquid crystal projectors, it is possible to improve the production efficiency and reduce the influence of individual differences of the light control element 6, and to perform stable light control processing. . Note that a low-pass filter may be applied to the light control parameter instead of the averaging process as described above.

(2) Method of limiting LUT dimming control parameters As in (1), an LUT is created in advance using a representative unit. Then, a limit value of the dimming control parameter is set in advance so that the flicker of the image is not recognized, and the LUT is readjusted. Specifically, for example, when the limit value is set to “10”, as shown in FIG. 8B, all dimming control parameters having values greater than “10” are converted to “10”. By re-adjusting the LUT with such a limit value, it is possible to reduce the flickering of the screen due to individual differences of the light control elements 6. Therefore, by deploying the LUT readjusted in this way to other liquid crystal projectors, it is possible to improve the production efficiency and reduce the influence of individual differences of the light control element 6, and to perform stable light control processing. .

  Note that, according to this method, for example, even if it is originally necessary to determine the dimming control parameter to be “20”, “10” is determined. Therefore, even if the flicker of the image can be reduced, the impression of the image is impaired. there is a possibility. Therefore, it is preferable to increase the dimming control parameters of other small values by a certain amount by limiting the maximum value of the dimming control parameters. Thereby, it is possible to reduce the flicker of the image without impairing the impression of the image.

(3) Method for Determining Dimming Control Parameter of Constant Value In this method, the dimming control parameter is set so that the flicker of the image is not recognized in the entire control range of the dimming element 6, that is, the entire rotation range of the stepping motor. decide. Specifically, for example, it is assumed that the change rate of the projection light quantity (brightness) with respect to the number of steps of the stepping motor is measured, and a measurement result as shown in FIG. 9 is obtained. As shown in this figure, it is assumed that the brightness change rate reaches the maximum value (0.5%) at 200 steps. When the brightness change rate at which the human eye can recognize the brightness change is about 2%, the brightness change rate does not exceed 2% even if the number of steps is changed by 4 steps before and after 200 steps. Accordingly, if these four steps, that is, “4” is determined as the light control parameter, the flicker of the image is not recognized in the entire rotation range of the stepping motor.

 In this way, a constant value of the dimming control parameter (“4”) is set regardless of the image parameter, and the dimming element 6 is controlled by the dimming control parameter, so that the screen due to individual differences of the dimming element 6 is displayed. It is possible to reduce flicker. Therefore, by developing the dimming control parameters set in this way to other liquid crystal projectors, it is possible to improve the production efficiency and reduce the influence of individual differences of the dimming elements 6, and to perform stable dimming processing. It is.

  Further, according to this method, the control efficiency is deteriorated in the control range where the brightness change is small, but it is not necessary to create the LUT, and therefore it is possible to reduce the load in the dimming process. As a countermeasure against the decrease in control efficiency as described above, for an image in which the brightness change is easily recognized by human eyes, such as a still image, the brightness change rate is adjusted to be within 2%. The light control parameter (“4” in the above example) is set, and the brightness change rate is kept within 4% in the case of an image in which the brightness change is difficult to be recognized by human eyes such as a moving image. It is preferable to set the dimming control parameter (“8” in the above example). Note that it is also possible to create a LUT once, extract the minimum value of the dimming control parameter from the LUT, and set the minimum value as the above-mentioned constant value of the dimming control parameter.

  As described above, according to the present embodiment, it is possible to determine the dimming control parameters that match the optical characteristics of the individual dimming elements 6. On the other hand, when emphasizing production efficiency, Since it is possible to determine a dimming control parameter that reduces the influence of individual differences, it is possible to improve production efficiency, reduce the influence of individual differences of the dimming element 6, and perform stable dimming processing. It is. In the case where importance is placed on production efficiency, the light control parameter may be determined by using a typical one, so that the other liquid crystal projector includes the light amount detection sensor 1, the first A / D converter 2, and the light control. The control parameter adjustment unit 3 is not necessary.

In addition, this invention is not limited to the said embodiment, For example, the following modifications can be considered.
(1) Although the stepping motor is used as the actuator of the light control element 6 in the above embodiment, the present invention is not limited to this, and a DC motor or a brushless motor may be used as the actuator. Further, although the light shielding plate is used as the light control element 6, the present invention is not limited thereto, and a liquid crystal light valve may be used as the light control element 6. Further, the technical scope of the present invention is not limited to such a light control means. For example, for a projector using a light control means that directly changes the output intensity of a light source such as a high-pressure mercury lamp or LED (light emitting diode). The present invention can also be applied.

(2) In the above embodiment, the light quantity detection sensor 1 is installed on the screen 527, and the optical characteristics of the light control element 6 are measured by detecting the projection light quantity. Further, the optical characteristic of the light control element 6 may be measured by installing the light quantity detection sensor 1 and detecting the illumination light quantity projected on the screen 527. In addition, the light quantity detection sensor 1 may be installed outside the optical path inside the liquid crystal projector, and the optical characteristics of the light control element 6 may be measured by detecting reflected light from optical elements such as various lenses and mirrors. In this case, it is preferable to display an all black pattern image as an image for adjustment used in the light control parameter adjustment mode. By displaying such an all black pattern image, it is possible to detect reflected light with higher accuracy.

(3) In the above-described embodiment, a liquid crystal projector using a transmissive liquid crystal device as the light modulation means is exemplified. However, the technical scope of the present invention is not limited to such a transmission type. For example, the present invention is applied to a reflection type projector such as LCOS or a projector using a mirror type spatial light modulator based on the MEMS technology. The invention can also be applied.

1 is a schematic configuration diagram of a liquid crystal projector according to an embodiment of the present invention. 1 is a block diagram illustrating a configuration of a drive circuit of a liquid crystal projector in one embodiment of the present invention. It is an operation | movement flowchart figure at the time of the light control parameter adjustment mode in one Embodiment of this invention. It is an example of the optical characteristic of the light control element 6 in one Embodiment of this invention. It is an example of the gamma characteristic of the liquid crystal projector in one embodiment of the present invention. It is explanatory drawing of LUT produced at the time of the light control parameter adjustment mode in one Embodiment of this invention. It is explanatory drawing which shows the expansion | extension processing method in one Embodiment of this invention. It is explanatory drawing of the LUT adjustment method in one Embodiment of this invention. It is explanatory drawing of the method of determining the light control parameter of a fixed value in one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Light quantity detection sensor, 2 ... 1st A / D converter, 3 ... Dimming control parameter adjustment part, 4 ... Dimming control part, 5 ... Dimming element driver, 6 ... Dimming element, 7 ... 2nd A / D converter,
DESCRIPTION OF SYMBOLS 8 ... Image parameter extraction part, 9 ... Decompression processing part, 10 ... D / A converter, 11 ... Light valve driver, 510 ... Light source, 511 ... Lamp, 512 ... Reflector, 513, 514 ... Dichroic mirror, 515, 516, 517 ... Reflection mirrors, 518, 519, 520 ... Relay lens, 522 ... Red light liquid crystal light valve, 523 ... Green light liquid crystal light valve, 524 ... Blue light liquid crystal light valve, 525 ... Cross dichroic prism, 526 ... Projection lens System, 21, 22 ... fly eye lens, 6a ... first light shielding plate, 6b ... second light shielding plate, 527 ... screen

Claims (7)

A dimming control parameter for controlling the dimming means of the image display device comprising a dimming means for dimming the illumination light emitted from the light source and a dimming control means for controlling the dimming means is determined. An adjustment device,
An interface for connecting to the image display device;
A light amount detecting means for detecting a light amount of the illumination light;
In the dimming control parameter adjustment mode, a dimming control parameter for measuring optical characteristics for controlling the dimming unit is output, and based on the amount of the illumination light detected according to the dimming control parameter. A dimming control parameter adjusting unit for determining optical characteristics of the dimming unit and creating reference data indicating a correspondence relationship between the dimming control parameter and an image parameter characterizing brightness of a display image based on the optical characteristic; With
The dimming control parameter adjusting means stores the reference data obtained by averaging the dimming control parameters in the dimming control means of the image display device via the interface. Equipment adjustment device. A dimming control parameter for controlling the dimming means of the image display device comprising a dimming means for dimming the illumination light emitted from the light source and a dimming control means for controlling the dimming means is determined. An adjustment device,
An interface for connecting to the image display device;
A light amount detecting means for detecting a light amount of the illumination light;
In the dimming control parameter adjustment mode, a dimming control parameter for measuring optical characteristics for controlling the dimming unit is output, and based on the amount of the illumination light detected according to the dimming control parameter. A dimming control parameter adjusting unit for determining optical characteristics of the dimming unit and creating reference data indicating a correspondence relationship between the dimming control parameter and an image parameter characterizing brightness of a display image based on the optical characteristic; With
The dimming control parameter adjusting means compares the dimming control parameter with a predetermined limit value, and if there is a dimming control parameter exceeding the limit value, converts the dimming control parameter into the limit value. An adjustment device for an image display device, wherein the reference data is stored in the dimming control means of the image display device via the interface. A dimming control parameter for controlling the dimming means of the image display device comprising a dimming means for dimming the illumination light emitted from the light source and a dimming control means for controlling the dimming means is determined. An adjustment device,
An interface for connecting to the image display device;
A light amount detecting means for detecting a light amount of the illumination light;
In the dimming control parameter adjustment mode, a dimming control parameter for measuring optical characteristics for controlling the dimming unit is output, and based on the amount of the illumination light detected according to the dimming control parameter. The optical characteristics of the light control means are determined, and based on the optical characteristics, a constant value of the light control parameter is determined so that no image flicker is recognized in the entire control range of the light control means. A dimming control parameter adjusting means for storing a dimming control parameter of the value in the dimming control means of the image display device via the interface;
A device for adjusting an image display device, comprising: An image display device comprising a dimming unit for dimming illumination light emitted from a light source, and a dimming control unit for controlling the dimming unit,
The dimming control means is the dimming control determined by the reference data created by the adjustment device for an image display device according to claim 1 or 2, or the adjustment device for the image display device according to claim 3. An image display device, wherein the light control means is controlled using a parameter . A dimming control parameter for controlling the dimming means of the image display device comprising a dimming means for dimming the illumination light emitted from the light source and a dimming control means for controlling the dimming means is determined. An adjustment method,
A first step of controlling the dimming means using a dimming control parameter for measuring optical characteristics and detecting the amount of illumination light in accordance with the dimming control parameter;
A second step of determining optical characteristics of the dimming means based on the amount of the illumination light detected according to the dimming control parameter;
A third step of creating reference data indicating a correspondence relationship between the dimming control parameter and the image parameter characterizing the brightness of the display image based on the optical characteristics;
A fourth step of performing an averaging process on the dimming control parameter included in the reference data;
A fifth step of storing the reference data after the fourth step in the dimming control means of the image display device;
A method for adjusting an image display device, comprising: A dimming control parameter for controlling the dimming means of the image display device comprising a dimming means for dimming the illumination light emitted from the light source and a dimming control means for controlling the dimming means is determined. An adjustment method,
A first step of controlling the dimming means using a dimming control parameter for measuring optical characteristics and detecting the amount of illumination light in accordance with the dimming control parameter;
A second step of determining optical characteristics of the dimming means based on the amount of the illumination light detected according to the dimming control parameter;
A third step of creating reference data indicating a correspondence relationship between the dimming control parameter and the image parameter characterizing the brightness of the display image based on the optical characteristics;
A fourth step of comparing the dimming control parameter included in the reference data with a predetermined limit value and, if there is a dimming control parameter exceeding the limit value, converting the dimming control parameter into the limit value. When,
A fifth step of storing the reference data after the fourth step in the dimming control means of the image display device;
A method for adjusting an image display device, comprising: A dimming control parameter for controlling the dimming means of the image display device comprising a dimming means for dimming the illumination light emitted from the light source and a dimming control means for controlling the dimming means is determined. An adjustment method,
A first step of controlling the dimming means using a dimming control parameter for measuring optical characteristics and detecting the amount of illumination light in accordance with the dimming control parameter;
A second step of determining optical characteristics of the dimming means based on the amount of the illumination light detected according to the dimming control parameter;
A third step of determining a dimming control parameter having a constant value such that image flicker is not recognized in the entire control range of the dimming unit based on the optical characteristics;
A fourth step of storing the constant light control parameter obtained in the third step in the light control means of the image display device;
A method for adjusting an image display device, comprising:

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