JP2005150922A - Device and method for regulating display state of projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correct an image signal accurately, such that only such unevenness of color as actually observed by naked eyes can be cancelled. <P>SOLUTION: An image signal S1, corresponding to a gray image, is outputted from an image signal feeder 51 based on a command signal from a measurement controller 33. The image signal S1 is fetched into the measurement controller 33 and eventually converted into a drive signal S5 for displaying a gray image on each liquid crystal light valves 25a-25c. Under that state, an imaging apparatus 31 is operated to photograph a transmission screen 18, and an image signal S10, corresponding to the luminance distribution of the transmission screen 18, is delivered to the measurement controller 33. The measurement controller 33 compares the image signal S10 from an imaging camera body 31b with the image signal S1 from the image signal feeder 51 and detects unevenness of luminance for each color in units of pixels from the difference. A control circuit 29e stores unevenness of luminance in a memory 29f, as correction data for use in an unevenness correction circuit 29c. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an adjustment apparatus and method for adjusting the display state of a projector that projects an image using a liquid crystal display panel or other display elements.

As a method for adjusting the display state of the projector, an image signal representing a uniform image is supplied to the image display device, and the output level of each color light at each position on the image displayed on the screen is measured and measured. There is a technique that obtains a data correction amount for each color to achieve a uniform image based on an output level (see Patent Document 1).
JP 2001-209358 A

  However, in the adjustment device as described above, since a color image on the screen is captured using a measuring device such as a video camera, the color division and luminance measurement by the video camera are the polarization states inherent in the image to be measured. Affected by. In other words, when the image projected on the projector screen has polarization unevenness, unevenness that differs greatly from the color unevenness observed with the naked eye due to the polarization dependence of the spectrum in a video camera or the like is detected. The data correction amount is inaccurate. When the image signal is corrected based on such an inaccurate color data correction amount, the color unevenness of the projected image is not properly corrected, and the uniformity is lost instead. For example, in a rear projection type liquid crystal projector, the image light of each color is originally polarized light, but such polarized light is locally disturbed particularly when passing through a projection lens including a plastic lens. It is partially disturbed during transmission through a rear projection screen. Such local or partial disturbance of the polarization state is observed as extreme color unevenness by a video camera or the like as polarization unevenness.

  Therefore, the present invention can correct the image signal accurately so as to cancel out only the color unevenness observed with the naked eye even when the image projected on the screen of the projector has uneven polarization. An object of the present invention is to provide an apparatus and method for adjusting the display state of a projector.

  In order to solve the above problems, an adjustment device according to the present invention is an adjustment device for a display state of a projector having a projection optical system that projects image light from a display element onto a screen, and (a) photographs the state of the screen. And (b) a depolarization means disposed between the screen and the main body of the imaging device.

  In the adjusting device, since the depolarization means is disposed between the screen and the main body of the imaging device, the image light projected on the screen via the projection optical system and visually observed is spatially nonuniform. Even when there is a polarization distribution, that is, polarization unevenness, it is possible to avoid such polarization unevenness being imaged by the imaging device as a screen state. Therefore, for example, the correction amount with respect to the initial display state on the screen more accurately reflects the actual observation result with the naked eye, and thus the operation state of the display element is corrected based on such an accurate correction amount. Thus, uneven brightness and uneven color of the projected image on the screen are corrected appropriately, and uniform brightness can be realized over the entire screen.

  Further, in a specific aspect of the present invention, in the adjustment device, the main body portion of the imaging device is divided by the color dividing means for color-dividing the image light by the dichroic mirror made of the dielectric multilayer film, and the color dividing means. An image sensor for each color that individually captures the image light of each color. In this case, an image photographed by the imaging apparatus can be easily color-divided and measured as an image of each color, and color unevenness can be easily detected. It should be noted that in the main body portion of the image pickup apparatus using the color dividing means as described above, the main body portion itself usually has a polarization dependency, and the image light projected on the screen and visually observed has uneven polarization. In the case of having, the image captured by the image pickup apparatus includes not only uneven color of the screen but also uneven polarization.

  In another specific aspect of the present invention, an adjustment device is further provided that sets an adjustment amount of the drive signal of the display element based on the imaging result of the screen. In this case, by setting the adjustment amount of the drive signal of the display element by the adjustment device, the operation state of the display element can be accurately corrected so that the color unevenness is canceled.

  In yet another specific aspect of the present invention, the display element adjusts the brightness of the display pixel by controlling the polarization direction of the illumination light. In this case, since the image light emitted from the display element has polarization characteristics, the polarization direction of the image light is disturbed through the projection optical system and the screen, and uneven polarization easily occurs. By the detection, uniform brightness can be realized over the entire screen.

  In still another specific embodiment of the present invention, the depolarizing means is formed by combining crystal members. In this case, the uneven polarization component of the image light can be easily and reliably removed.

  In yet another specific aspect of the present invention, the projector includes a rear projection screen on which image light that has passed through the projection optical system is projected from the rear. In this case, polarization unevenness is likely to occur when the image light passes through the rear projection type screen. However, as described above, since the image detection that cancels the polarization unevenness is performed, the brightness is uniform over the entire screen. Can be realized.

  In still another specific embodiment of the present invention, image light having uneven polarization is projected on the screen. In this case, the visually observed image light has uneven polarization, but as described above, image detection that cancels out this uneven polarization is performed, so that uniform brightness is achieved across the entire screen. can do.

  In still another specific aspect of the invention, the projection optical system includes a plastic lens. In this case, the imaging performance of the projection optical system can be improved by making the plastic lens aspherical or the like. However, in a plastic lens, there is a possibility that local polarization unevenness may occur due to birefringence due to residual stress. However, as described above, image detection that cancels such polarization unevenness is performed, so that it is uniform over the entire screen. Brightness can be realized.

  According to still another specific aspect of the present invention, an adjustment method according to the present invention is a method for adjusting a display state of a projector having a projection optical system that projects image light from a display element onto a screen, And (b) a step of photographing the state of the screen by the main body portion of the image pickup device through the depolarization means.

  In the above adjustment method, since the depolarizing means is disposed between the screen and the main body of the imaging device, the image light projected on the screen via the projection optical system and visually observed is not spatially defective. Even in the case of having uniform polarization characteristics, that is, polarization unevenness, it is possible to avoid such polarization unevenness being photographed by the imaging device as a screen state. Therefore, for example, the correction amount with respect to the initial display state on the screen more accurately reflects the actual observation result with the naked eye, and thus the operation state of the display element is corrected based on such an accurate correction amount. Thus, uneven brightness and uneven color of the projected image on the screen are corrected appropriately, and uniform brightness can be realized over the entire screen.

  In a specific aspect of the present invention, the adjustment device further includes a step of setting an adjustment amount of the drive signal of the display element based on the imaging result of the screen. In this case, by setting the adjustment amount of the drive signal of the display element, the display state of the display element can be accurately corrected so that the color unevenness is canceled.

  FIG. 1 is a diagram illustrating a system including an adjustment device according to an embodiment of the present invention and a projector whose display state is to be adjusted by the adjustment device. In other words, the illustrated system includes a projector 10 for forming a projection image such as a video image or a digital image, and an adjustment device 30 for adjusting the display state of the projector 10 with respect to luminance unevenness or color unevenness.

  Among these, the projector 10 is a rear projection type device that displays an image by rear projection, and includes a projector body 14 at the bottom of a case 12 that is a housing, and a reflection mirror 16 at the upper rear side in the case 12. A transmissive screen 18 is provided in front of the case 12. The image light emitted from the projector main body 14 travels obliquely upward and backward with the optical axis OA1 as the center, is bent to the front side by the reflection mirror 16 with the optical axis OA2 as the center, and enters the transmissive screen 18. The projector main body 14, the reflection mirror 16, and the transmissive screen 18 are positioned and fixed in the case 12 by means not shown.

  On the other hand, the adjustment device 30 is for uniformizing the white level of the projector 10 over the entire screen portion, and is based on the imaging device 31 that images the transmission screen 18 and the measurement result of the imaging device 31. And a measurement control device 33 that sets an adjustment amount of a drive signal to be input to the light modulation unit 25 provided in the projector main body 14. Among these, the former imaging device 31 includes a depolarizer 31a which is a depolarizing means and an imaging camera body 31b which is a main body portion, and takes an image of the transmissive screen 18 via the depolarizer 31a. The image signal corresponding to the luminance distribution in the display state is output to the measurement control device 33. The reason for observing the transmissive screen 18 using the imaging device 31 in this way is that the display of the transmissive screen 18 has an angle dependency, and the transmissive screen 18 is observed with the naked eye. This is because it is desirable to observe the transmissive screen 18 from the viewpoint of the user of the projector 10 in order to reduce the luminance unevenness. Further, the latter measurement control device 33 adjusts the amount of adjustment of the drive signal input to the light modulation unit 25 based on the image signal output from the imaging camera body 31b, that is, the color unevenness remaining in the white display state of the transmissive screen 18, for example. A color unevenness correction amount (correction data) that cancels the above is appropriately set.

  FIG. 2 is a block diagram for specifically explaining the structures and functions of the projector main body 14 and the adjusting device 30 shown in FIG. First, the projector body 14 includes a light source device 21 that generates light source light, a dichroic mirror (not shown) and the like, a color division optical system 23 that divides the light source light from the light source device 21 into three colors of RGB, and color division. A light modulation unit 25 composed of three liquid crystal light valves 25a, 25b, and 25c that are respectively illuminated by illumination light of each color emitted from the optical system 23, and a cross dichroic prism that combines image light of each color from the light modulation unit 25 27, a projection lens 28 which is a projection optical system for projecting the image light having passed through the cross dichroic prism 27 onto the transmission screen 18, and a circuit portion 29 for appropriately operating the light modulator 25 and the like.

  The circuit portion 29 incorporated in the projector main body 14 includes an image converter 29a, a gamma correction circuit 29b, an unevenness correction circuit 29c, a liquid crystal light valve driving circuit 29d, a control circuit 29e, and a memory 29f. Here, the image converter 29a is a digital image adapted to drive each of the liquid crystal light valves 25a, 25b, and 25c, each of which is a display element, based on the image signal S1 input from the image signal supply device 51 provided outside. Signal S2 is generated. The digital image signal S2 is appropriately nonlinearly corrected according to the input / output characteristics of the liquid crystal light valves 25a, 25b, and 25c by the gamma correction circuit 29b to obtain a gamma correction signal S3. The gamma correction signal S3 is subjected to correction data addition and integration processing that cancels out the color unevenness appearing on the transmissive screen 18 by the unevenness correction circuit 29c, and becomes the unevenness correction signal S4. The unevenness correction signal S4 is converted into a drive signal S5 by the liquid crystal light valve drive circuit 29d and is output to each of the liquid crystal light valves 25a, 25b and 25c to cause them to perform a display operation. The control circuit 29e comprehensively controls operations of the image converter 29a, the gamma correction circuit 29b, and the unevenness correction circuit 29c. At this time, for example, signal processing in the gamma correction circuit 29b is performed based on the conversion data stored in the memory 29f, and further, signal processing in the unevenness correction circuit 29c is performed based on the correction data stored in the memory 29f.

  The measurement control device 33 compares the image signal S10 output from the imaging camera body 31b with the image signal S1 output from the image signal supply device 51, and determines the luminance unevenness amount, that is, the color unevenness amount for each color from the difference. Detect by unit. The control circuit 29e calculates correction data for operating the unevenness correction circuit 29c based on the color unevenness amount output from the measurement control device 33, and stores it in the memory 29f. Here, the unevenness correction circuit 29 c, the control circuit 29 e, the memory 29 f, and the image signal supply device 51 constitute an adjustment device 30 together with the imaging device 31 and the measurement control device 33.

  FIG. 3 is a diagram illustrating an example of the optical system portion of the imaging camera body 31b. This optical system portion is composed of three dichroic prisms 61, 62, and 63 that are color dividing means and three CCD image sensors 65, 66, and 67 that are image sensors corresponding to three colors of RGB. The image light incident on the first surface 61a of the first dichroic prism 61 through an imaging lens (not shown) is incident on the second surface 61b opposite to the first surface 61a. Of the image light mixed with RGB, the B light is reflected by the second surface 61b with the dichroic coating, further totally reflected by the first surface 61a, and emitted from the third surface 61c to be emitted from the CCD image sensor 65 for B light. Is incident on. Similarly, the image light, that is, the R light and the G light that have passed through the second surface 61b and entered the first surface 62a of the second dichroic prism 62 are incident on the second surface 62b that faces the first surface 62a. . Among these, the R light is reflected by the second surface 62b on which the dichroic coating is applied, is further totally reflected by the first surface 62a, is emitted from the third surface 62c, and is incident on the CCD image sensor 66 for R light. Further, the G light that has passed through the second surface 62b and entered the first surface 63a of the third dichroic prism 63 is emitted from the second surface 63b that faces the first surface 63a, and is used for the G light CCD imaging device. 67 is incident.

  In the color splitting optical system including the dichroic prisms 61, 62, and 63 as described above, since the color splitting is performed using the dichroic coating formed of the dielectric multilayer film, the light quantity loss hardly occurs, but the polarization dependence thereof. Due to the property, polarization unevenness on the transmission screen 18 is observed as brightness unevenness. More specifically, the transmission characteristics of the dichroic coating provided on the second surface 61b of the dichroic prism 61 and the second surface 62b of the dichroic prism 62 have a large polarization dependency. That is, the transmission characteristics of the dichroic coating have a difference in edge wavelength between S-polarized light and P-polarized light. As a result, the images of the respective colors observed by the CCD image pickup devices 65, 66, and 67 after the color division are in a state of being observed through a band pass filter or a special polarizing filter. When polarization unevenness exists, such polarization unevenness is observed as luminance unevenness or color unevenness having a certain correlation with the degree of polarization unevenness. That is, the polarization unevenness is mistakenly recognized as the brightness unevenness, and overcorrection is performed. For this reason, in the present embodiment, as shown in FIG. 1 and the like, the depolarizer 31a is disposed in front of the imaging camera body 31b to prevent the polarization unevenness from being measured as luminance unevenness or color unevenness.

  FIG. 4 is a diagram for explaining the polarization unevenness of the projector 10 shown in FIG. 1, and FIG. 4 (a) is a diagram of the resin lens disposed at the exit end of the projection lens 28 as seen from the optical axis direction. FIG. 4B is a diagram showing luminance unevenness observed in the image enlarged and projected on the transmissive screen 18.

  In FIG. 4A, when the resin lens 28a of the projection lens 28 is observed through a polarizing filter, dark portions DA1 are observed at four surrounding locations. Such a dark portion DA1 is formed by residual stress when the resin lens 28a is injection molded. That is, when the resin lens 28a is injection-molded, stress remains in the lens during the cooling process, and partial birefringence occurs in the lens due to such residual stress. Such birefringence gives nonuniform polarization dependence to the imaging characteristics of the resin lens 28a, so that the image light formed by the projection lens 28 has a spatially nonuniform polarization distribution, that is, It will have polarization unevenness. The residual stress of the resin lens 28a is likely to occur when the resin lens 28a is molded using a resin whose refractive index has little temperature dependency.

  Further, in FIG. 4B, when the transmission screen 18 is observed with the naked eye, dark portions DA2 (or color unevenness portions) are observed at the four surrounding locations. Image light emitted from the liquid crystal light valves 25a, 25b, and 25c shown in FIG. 2 is generally linearly polarized in either direction, but passes through a resin lens 28a as shown in FIG. The polarization is partially disturbed by the partial birefringence of the resin lens 28a. Also, the transmission screen 18 and the reflection mirror 16 shown in FIG. 2 often have polarization dependency, and the spatial polarization distribution of image light is partially disturbed. Furthermore, there may be a difference in the degree of polarization in each color image immediately after exiting the liquid crystal light valves 25a, 25b, and 25c, and the polarization characteristics slightly change on the entrance / exit surfaces of the element lenses constituting the projection lens 28. There is also. Such a disturbance of polarization is hardly recognized visually. That is, when polarization unevenness due to polarization disturbance is formed on the projection lens 28, the transmission screen 18, the reflection mirror 16, etc., the brightness unevenness that can be normally perceived by the naked eye is almost unobservable. When it passes through, it is clearly observed as uneven polarization. For this reason, in the present embodiment, the depolarizer 31a is disposed between the transmission screen 18 and the imaging camera body 31b and immediately before the imaging camera body 31b. Thereby, even if the image light when photographing the transmissive screen 18 has uneven polarization, such uneven polarization can be solved by the depolarizer 31a. Therefore, the image on the transmissive screen 18 photographed by the imaging camera body 31b is an image having no polarization unevenness, and luminance unevenness or color unevenness close to a state where the imaging camera body 31b is observed with the naked eye is a highly accurate image. Detected.

  FIG. 5 is a diagram illustrating the structure of the depolarizer 31a. The depolarizer 31a is called a well-known Cornu Pseudo depolarizer, and a right crystal portion 31f and a left crystal portion 31g each having a slope SP inclined by 45 ° with respect to the optical axis OA are joined by the slope SP of both. Is. Here, the right crystal part 31f and the left crystal part 31g, which are a pair of crystal members, have optically opposing properties. Thus, when the incident beam enters the depolarizer 31a along the optical axis OA, the incident beam that is linearly polarized light is converted into a linearly polarized state that is complicated and spatially continuously changes. Accordingly, each of the RGB image lights incident on the depolarizer 31a is converted into a non-polarized state and emitted as an emitted beam. The depolarizer 31a as described above is not limited to being arranged in one stage, and can be arranged in a plurality of stages. Moreover, not only a Cornu pseudo depolarizer but various depolarizers can be used.

  Hereinafter, the overall operation of the projector 10 shown in FIGS. 1 and 2 will be described. The light source light from the light source device 21 is color-divided by the color-dividing optical system 23 and is incident on the liquid crystal light valves 25 a to 25 c of the respective colors provided in the light modulation unit 25 as illumination light. Each of the liquid crystal light valves 25a to 25c is modulated in accordance with the image signal output from the image signal supply device 51 to have a two-dimensional refractive index distribution, and modulates the illumination light two-dimensionally in pixel units. To do. As described above, the illumination light, that is, the image light modulated for each color by the light modulator 25 is combined by the cross dichroic prism 27 and enters the projection lens 28. The image light incident on the projection lens 28 is projected on the transmission screen 18 through the reflection mirror 16.

  Next, an initial setting operation of the projector 10 by the adjustment device 30 will be described. First, an image signal S1 corresponding to a gray image is output from the image signal supply device 51 based on a command signal from the measurement control device 33, and the image signal S1 is taken into the measurement control device 33. The image signal S1 is sequentially processed through an image converter 29a, a gamma correction circuit 29b, a non-uniformity correction circuit 29c, and a liquid crystal light valve drive circuit 29d to be converted into a drive signal S5, and a gray image is applied to each of the liquid crystal light valves 25a to 25c. Display corresponding to. At this time, the correction operation of the unevenness correction circuit 29c is stopped. In this state, the imaging device 31 is operated to photograph the transmissive screen 18, and an image signal S 10 corresponding to the luminance distribution of the projected image on the transmissive screen 18 is output to the measurement control device 33. The measurement control device 33 compares the image signal S10 from the imaging camera body 31b with the image signal S1 from the image signal supply device 51, and detects the luminance unevenness amount for each color from the difference. Further, the measurement control device 33 stores the luminance unevenness amount in the memory 29f via the control circuit 29e as correction data used in the unevenness correction circuit 29c.

  During the normal display operation of the projector 10, the adjustment device 30 does not perform the adjustment operation. Specifically, an image signal S1 to be projected on the transmission screen 18 is output from the image signal supply device 51 to the circuit portion 29 of the projector main body 14, and an image converter 29a, a gamma correction circuit 29b, an unevenness correction circuit 29c, and a liquid crystal are output. Appropriate signal processing is performed by the light valve drive circuit 29d and the like, and the liquid crystal light valves 25a, 25b, and 25c perform display operations. At this time, signal processing in the unevenness correction circuit 29c is performed based on the correction data stored in the memory 29f. Thereby, an image with uniform brightness (image with a uniform white level) can be projected over the entire transmissive screen 18.

  As described above, the present invention has been described according to the embodiment, but the present invention is not limited to the above embodiment. For example, in the above-described embodiment, the unevenness correction circuit 29c is incorporated in the next stage of the gamma correction circuit 29b. However, the place where the unevenness correction circuit 29c is incorporated is an arbitrary place from the image signal supply device 51 to the liquid crystal light valve drive circuit 29d. can do. However, in that case, it is necessary to appropriately adjust the format, amount, etc. of the correction data stored in the memory 29f according to the location where the unevenness correction circuit 29c is incorporated.

  Further, in the above embodiment, the adjustment device 30 applied to the rear projection type projector 10 has been described. However, even in the case of a projector that projects from the front, if the screen has polarization dependence, the same as described above. Since the polarization unevenness is observed according to the principle, the brightness unevenness corresponding to the naked eye observation can be measured by inserting the depolarizer 31a in front of the imaging camera body 31b, and an image with uniform brightness over the entire screen. Can be projected.

It is a figure explaining the adjustment apparatus which concerns on one Embodiment. FIG. 2 is a block diagram specifically explaining a projector main body and the like shown in FIG. 1. It is a figure explaining an example of the optical system part of an imaging camera main body. (A), (b) is a figure which shows a projection lens and a transmissive screen. It is a figure explaining the example of 1 structure of a depolarizer.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Projector, 14 ... Projector main body, 16 ... Reflection mirror, 18 ... Transmission type screen, 21 ... Light source device, 23 ... Color division optical system, 25 ... Light modulation part, 25a, 25b, 25c ... Liquid crystal light valve, 28 ... Projection lens, 28a ... resin lens, 29 ... circuit portion, 29a ... image converter, 29b ... gamma correction circuit, 29c ... non-uniformity correction circuit, 29d ... liquid crystal light valve drive circuit, 29e ... control circuit, 29f ... memory, 30 ... Adjustment device 31 ... Imaging device 31a ... Depolarizer 31b ... Imaging camera body 33 ... Measurement control device 61, 62, 63 ... Dichroic prism 65, 66, 67 ... Imaging device

Claims (10)

An apparatus for adjusting the display state of a projector having a projection optical system that projects image light from a display element onto a screen,
A main body portion of an imaging device for photographing the state of the screen;
An adjustment device comprising depolarization means disposed between the screen and a main body portion of the imaging device.   The main body of the imaging device includes a color dividing unit that color-divides image light by a dichroic mirror made of a dielectric multilayer film, and an image sensor for each color that individually images the image light of each color divided by the color dividing unit. The adjustment device according to claim 1, further comprising:   The adjustment device according to claim 1, further comprising an adjustment device that sets an adjustment amount of a drive signal of the display element based on an imaging result of the screen.   4. The adjustment device according to claim 1, wherein the display element adjusts brightness of a display pixel by controlling a polarization direction of illumination light. 5.   The adjusting device according to any one of claims 1 to 4, wherein the depolarizing means is formed by combining crystal members.   The adjusting device according to any one of claims 1 to 5, wherein the projector includes a rear projection screen on which image light that has passed through the projection optical system is projected from the rear.   The adjusting device according to claim 6, wherein image light having uneven polarization is projected onto the screen.   The adjustment apparatus according to claim 1, wherein the projection optical system includes a plastic lens. A method for adjusting a display state of a projector having a projection optical system that projects image light from a display element onto a screen,
Disposing depolarization means between the screen and the body portion of the imaging device;
And a step of photographing the state of the screen by the main body portion of the imaging device via the depolarization means.   The adjustment method according to claim 9, further comprising a step of setting an adjustment amount of a drive signal for the display element based on an imaging result of the screen.

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