JP2002214700A - Rear projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an accurate automatic adjusting mechanism where the individual difference (variance) of a photodetecting means is eliminated in the case of arranging a plurality of photodetecting means in a screen and automatically adjusting brightness or color balance in a rear projector. SOLUTION: This rear projector 1 equipped with a projecting device 10 and a screen 60 is equipped with a plurality of condensing means 20 provided in the optical path of video light 80, a plurality of light transmitting means 30 guiding the light from the condensing means 20 to a photodetector 40, the photodetector 40 equipped with an optical shutter means and the photodetecting means and detecting the luminance and the color balance of the video light and an automatic correction circuit 50 correcting the luminance and the color balance of the video light based on detection data from the photodetector 40. Then, the luminance and the color balance of the condensing means selected by the optical shutter means are detected by one photodetecting means, and the luminance and the color balance are corrected based on the detection data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a rear projector having a PRT system or a light valve. further,
The present invention relates to a rear projector that automatically adjusts luminance and color balance of a projector based on luminance and color balance in an optical path, and more particularly to a rear projector that can realize highly accurate correction even on a multi-screen.

[0002]

2. Description of the Related Art In a conventional rear projector system using a projection system, a plurality of light sources are arranged on a screen as disclosed in Japanese Patent Application Laid-Open No. 7-162790 in order to uniformly and automatically adjust the luminance and color balance within one plane. Means for arranging sensors and performing automatic adjustment have been devised. However, this configuration requires absolute measurement accuracy for each sensor, and also requires stability such that the effect on the environment is extremely small and there is almost no change over time. This is because if the measurement sensitivity of each sensor changes with individual differences due to a temperature change, aging, or the like, a good adjustment result cannot be obtained on the entire screen as a result. Therefore, in this method, extremely high stability is required for the sensor itself. However, since even luminance and color balance measuring instruments manufactured for the purpose of measuring absolute values generally have frequent calibrations and errors in measured values, individual sensors such as those known in the art have high accuracy. Therefore, it is difficult to realize an automatic adjustment device that requires high stability, and it is expected that good correction results cannot be expected.

As disclosed in Japanese Patent Application Laid-Open No. 10-90645, a method has been devised for automatically correcting the luminance and color balance even in a projector having a multi-screen. However, in the method of this known example, an optical sensor is provided in each rear projector, and information of an independent optical sensor is used as a correction between the multi-screen rear projectors. Absolute measurement accuracy and stability are required for each sensor of the projector.

[0004]

SUMMARY OF THE INVENTION The present invention relates to the automatic adjustment of a rear projector, and more particularly to the system of a rear projector used for a multi-screen, the inherent sensitivity between the optical sensors when using a plurality of optical sensors. It is an object of the present invention to provide a rear projector having an automatic brightness / color balance adjustment device which is not affected by variations and stability of the projector.

[0005]

SUMMARY OF THE INVENTION Variations in light detection means, which are problematic when a plurality of light detection means (light sensors) are provided in a screen, are reduced by a plurality of light collection means instead of the plurality of light detection means. Is arranged in a screen, and the light collected from the light collecting means is guided to one light detecting means via the light transmitting means. According to this configuration, since the light detecting means detects the luminance and the color of the light from any of the light collecting means by the same light detecting means, it is possible to eliminate any variation among the conventional plurality of light detecting means. it can.

[0006] Further, regarding the arrangement of the light condensing means, in a reflection type rear projector which folds an image from the projector and projects the image on a screen, the light converging means is arranged on the back side of a reflecting mirror, and the brightness of the light is detected by the light detecting means. The need to remove the light condensing means is eliminated even when no color or color is detected.

[0007] Variations between the light detecting means provided in each rear projector, which is a problem when correcting the color balance between the multi-screen rear projectors, can be solved by the following means.

In addition to the structure of the above-mentioned solving means, in addition to the rear projector, the light condensing means is arranged at at least one place which is a reference for luminance and color of another rear projector, and the light detection of the own rear projector is performed. If the configuration is such that the state of the luminance and color balance detected by the means is compared with the state of the luminance and color balance of another rear projector obtained from the condensing means arranged in another rear projector and calibrated, the multi-screen rear projector This is equivalent to performing the measurement with the same light detecting means, and it is possible to correlate the luminance and color balance between the multi-screen rear projectors.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a conceptual diagram conceptually illustrating a basic configuration of a rear projector according to the present invention.
FIG. 2 is a conceptual diagram conceptually illustrating the structure of a light detection device used in the rear projector according to the present invention.

A rear projector 1 according to the present invention shown in FIG. 1 is a light valve type projection device (projector) 1 for modulating light from a light source using a PRT method or liquid crystal.
0, and a plurality of light condensing means 20 arranged on the optical path of light projected from the projector 10 to the screen 60 for condensing light from the projector 10. Light transmitting means 30 comprising an optical fiber for transmitting the light collected by the light collecting means 20 to the light detecting device 40
A light detection device 40 for selecting light of a desired optical fiber from the plurality of optical fibers 30 and measuring luminance and color balance with built-in light detection means, and a light source of the projector 10 based on the measurement result of the light detection device 40 And an automatic correction circuit 50 for calculating a correction value for controlling output correction. Since the automatic correction circuit 50 can be realized by a known technique, a detailed description is omitted.

Referring to FIG. 2, a specific configuration of the light detecting device 40 will be described. The light detecting device 40 selectively detects only light from the light detecting means 41 composed of a CCD, a solar cell, or the like and light from the light collecting means to be measured among the plurality of optical fibers 30 transmitted to the light detecting device 40. And an optical shutter means 42 for outputting to the light detecting means 41. The light collected by the plurality of light condensing means 20 is respectively transmitted to the optical fiber 30.
And is guided to just before the light detecting means 41.

Hereinafter, embodiments of the present invention will be described in detail. A plurality of light condensing means 20 for collecting light in the vicinity of the optical path of the image light projected from the projector 10 toward the screen 60 are installed at necessary places, and the projected light is detected. The light collected by the light condensing means 20 is
The light is collected by the light detection device 40 via the light transmission means. In the light detecting device 40, by selecting the light of the part to be measured by the light shutter means 42, only the light of the part to be measured is guided to the light detecting means 41 composed of a CCD, a solar cell or the like. Automatic correction circuit 5 using data on the state of luminance and color balance measured by light detection means 41
An appropriate correction value is calculated with 0, and the correction value is output to the projector 10.

The brightness and color balance of each point on the screen are automatically corrected using the feedback loop having the above-described configuration. The control processing of the entire rear projector is performed by an arithmetic control unit such as a microcomputer not shown.

In this description, the example in which the light condensing means 20 is provided on the projector 10 side of the screen 60 has been described. However, since the screen 60 is a transmission type screen, the light condensing means 20 ' May be provided.

According to the above configuration, since the luminance and the color balance of each point on the screen can be always detected by one light detecting means 41, as in the case of using a plurality of light detecting means. It is not necessary to consider variations in the sensitivity between the light detecting means caused by individual differences of the detecting means and changes over time.

Here, a similar effect can be expected by a known method of performing correction while moving a single sensor in a screen as disclosed in Japanese Patent Application Laid-Open No. 10-90645. It is necessary to move and hold the sensor to the correct position,
Since a fixing mechanism has to be constructed, it tends to be an expensive system. According to the present invention, it is possible to construct a mechanically stable light collecting means with a relatively simple structure without a movable portion in the light collecting means.

Now, when considering the actual correction, it is somewhat difficult to perform an accurate correction from the beginning with the correction means having the above configuration, when the correction is considered by narrowing the correction points to some extent as in the present invention. Therefore, as a means for exhibiting the features of the present invention most effectively, the light from the light condensing means 20 is adjusted by the light detecting means 42 before the light from the light collecting means 20 is adjusted sufficiently accurately in a factory or at the time of installation adjustment. The initial adjustment state is measured and stored as an initial value in a memory (not shown) provided in the automatic correction means 50, and thereafter, the brightness and color around the light condensing means are corrected to the initial value. Thus, an effect of always providing a screen image equivalent to the initial value can be expected. In a light valve system that modulates light from a light source using a liquid crystal or the like, when it is assumed that the light gradually becomes dark in consideration of a decrease in luminance due to deterioration of a lamp of the light source, the center in an initial state is used. What is necessary is just to normalize based on the luminance of the unit, and to correct so as to be in the normalized state.

Here, in the configuration of FIG.
There is a problem that the light condensing means 20 creates a shadow on the above projected image. In order to eliminate this adverse effect, it is necessary to install the condensing means 20 in the optical path of the projection light between the projector 10 and the screen 60 every time the automatic adjustment is performed. In order to maintain it, it is necessary to always install the light condensing means 20 at the same position, and the installation structure for that purpose requires considerable accuracy, and the adjustment itself may be complicated.

Therefore, a modification of the arrangement of the light converging means 20 in the folding rear projector using the reflecting mirror according to the second embodiment of the present invention, which solves this problem, will be described with reference to FIGS. Will be explained. FIG. 3 is a conceptual diagram conceptually illustrating the basic configuration of the folding rear projector, and FIG. 4 is a conceptual diagram conceptually illustrating the configuration of the light collecting unit 20.

As shown in FIG. 3, in this example, a reflecting mirror 15 is provided in the middle of the optical path of the projection light 80 from the projector 10 to the screen 60, and the focusing means 2 is provided behind the reflecting mirror 15.
0 is provided. As shown in FIG. 4, the light condensing means 20 disposed on the back surface of the reflecting mirror 15 transmits the weak transmitted light 80-2 not reflected by the reflecting mirror 15 to the opening surface 3 of the optical fiber 30.
1 is provided with a light-collecting device 21 such as a convex lens that collects light. The optical axis of the light condensing device 21 is
Are arranged so as to be substantially in line with the optical axis of the projection light 80 from the camera.

Most of the projection light 80 from the projector 10 strikes the reflecting mirror 15 and is reflected.
And arrives at the screen 60. Very little (several percent) of the transmitted light 80-2 that is not reflected by the reflecting mirror 15 and passes through the reflecting mirror 15 reaches the light collecting means 20. Transmitted light 80-
2 itself is weak, and a light-collecting device 21 such as a convex lens is arranged for the purpose of collecting light enough for the light detecting means 41 to bring out sufficient performance. By arranging the light condensing device 21 so that the optical axis thereof is substantially aligned with the projection light 80 from the projector 10, the arrangement is such that only the projection light 80 from the projector 10 is selectively condensed, and a measurement error factor Thus, the influence of unnecessary light 90 such as illumination light leaked through the screen, which adversely affects the correction accuracy, can be prevented.

By adopting such a configuration, it is not necessary to attach or detach the light collecting means 20 in the optical path each time the automatic adjustment is performed, so that no special structure is required and the mounting state is stabilized. Thus, highly accurate adjustment can always be performed.

Next, a method of applying the present invention to a multi-screen rear projector using the structure of the present invention will be described. If the present invention is applied to the multi-screen rear projector system as it is, the light condensing means 20 is provided at a necessary portion of the rear projector constituting the multi-screen rear projector.
The same operation can be expected in principle if the light from each light condensing means is collected by the optical fiber 30 to one light detecting means 41 and the whole multi-screen rear projector is controlled by one control device.

However, when the number of screens of the multi-screen increases, the number of light condensing means 20 becomes enormous, and the switching mechanism of the optical fiber composed of the optical shutter means 42 becomes complicated. Becomes difficult. A third embodiment of the present invention for solving this will be described with reference to FIG.

In FIG. 5, the multi-screen rear projector 2 includes a light condensing means 20 and a light detecting device 40, respectively.
And a plurality of rear projectors 1-1, 1-2, 1-3, and 1-4, which are connected to each other by an optical fiber 30. Here, it is assumed that the rear projector 1-1 is a reference rear projector. The other common parts are denoted by the same reference numerals and description thereof is omitted.

In order to solve the above-mentioned problems, each of the rear projectors 1-1 and 1-1 is similarly arranged in the same manner as in the above-described configuration of the present invention.
-2, 1-3, and 1-4, each of which is provided with a plurality of light condensing means 20 and a light detection device 40, and as shown in FIG. Light collecting means 20
-2, 20-3, and 20-4 are arranged in a reference portion (center portion in the drawing) of another adjacent rear projector 1-1, 1-2, and 1-3, and the other Automatically adjusts its own brightness and color to match the brightness and color of the reference part of the reference rear projector by detecting the brightness and color of the reference part of the rear projector with its own light detection device . As described above, by sequentially matching the reference rear projector 1-1, the overall brightness and color of the multi-screen rear projector 2 can be automatically adjusted.

Hereinafter, this mechanism will be described in detail. First,
The reference rear projector 1-1 collects the detection light from the condensing means 20-1 that has detected the projection light to the projector into the light detection device 40-1 by the optical fiber 30, and the rear projector 1-1 alone uses Apply automatic correction. Next, the adjacent rear projector 1-2 is connected to the rear projector 1-2.
Of the projection device 10- so that the detection light of the light collecting means 20-2 arranged in the reference portion of the reference projector 20-1 is equal to the detection light of the light collecting means 20-2 arranged in the reference portion of the reference rear projector 1-1. 2 based on the correction information, so that the detection light of the reference portion and other portions collected by the light collecting means 20-2 arranged in the rear projector 1-2 itself becomes a predetermined value. Perform correction processing.

When there are three or more rear projectors (FIG. 5)
In this case, information on the luminance and color of the reference portion of the second rear projector 1-2 is stored in the third rear projector 1-2.
The light detection device 40-3 of the third device itself may similarly acquire the data and perform automatic correction. In this manner, the correlation between the luminance and the color balance can be obtained in the plurality of rear projectors, and a multi-screen rear projector having no variation in luminance and color between screens can be manufactured as the whole multi-screen rear projector 2.

That is, a plurality of sensors are used as a multi-screen rear projector in order to arrange the light detecting device 40 in each of the rear projectors, but each of the rear projectors is disposed in a portion which is a reference of an adjacent rear projector. Since the reference brightness and color can be successively received from the reference rear projector via the light condensing means, the result is equivalent to calibrating the correction value. Therefore, even when individual photodetectors have individual differences due to aging or environmental changes, good correction results can be expected for the entire multi-screen rear projector.

However, when the above-described method is applied to a multi-screen rear projector having an extremely large number of screens, a considerable amount of error occurs, and the adjustment result between the reference rear projector and the rear projector that is finally adjusted is adjusted. There is a concern that there will be a slight difference. In order to solve such a problem, for example, in the case of 16 screens as shown in FIG. 6, the entire multi-screen rear projector is divided into groups 1-1 to 1-4 each having four screens. In FIG. 6, the leftmost uppermost rear projector 1-1-1) and a rear projector serving as a reference for each of the groups (in FIG. 6, rear projectors 1-2-1, 1-3-1, 1-1 having a black circle at the center). -4-1), and then the reference rear projector 1-1 of each group.
1, 1-2-1, 1-3-1, 1-4-1 and other rear projectors 1-n-2, 1-n-3, 1 in the group.
By adopting a hierarchical structure in which −n−4 is adjusted, variations in correction can be scattered over the entire screen, and a good correction result in which a correction error is less noticeable even in a large-scale multi-screen rear projector can be expected.

[0031]

According to the present invention, in the function of automatically adjusting the luminance and color balance of the rear projector, it is possible to realize a stable automatic adjustment function that is not affected by individual differences of the light detecting means.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating the concept of the basic configuration of a rear projector according to the present invention.

FIG. 2 is a conceptual diagram schematically illustrating the structure of a photodetector.

FIG. 3 is a conceptual diagram illustrating the concept of the basic configuration of the rear projector of the folding type.

FIG. 4 is a conceptual diagram for explaining an outline of a structure of a light condensing means in the rear projector of the folding type.

FIG. 5 is a diagram illustrating a configuration when the present invention is applied to a multi-screen rear projector.

FIG. 6 is a diagram illustrating a configuration when the present invention is applied to a large-scale multi-screen rear projector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Projector (projection apparatus) 15 Reflecting mirror 20 Light condensing means 21 Light condensing device 30 Optical fiber 31 Light condensing surface 40 Light detecting device 41 Light detecting means 42 Optical shutter means 50 Automatic correction circuit 60 Screen 80 Projection light from a projector 80- 1 reflected light 80-2 transmitted light 90 unnecessary light such as lighting

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroyuki Shinji 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture F-term in Hitachi Image Information System Co., Ltd. 5C060 BA04 GA02 GD01 HB16 HC00 JA11 JA13

Claims (5)

[Claims] 1. A PRT system or a light valve as a light source,
In a rear projector that projects video light from the back of a screen using a projector that modulates the light, light near the light is provided at a plurality of locations in the optical path of the video light projected from the projector onto the screen. A plurality of light collecting means for collecting light, a plurality of light transmitting means for guiding light from the light collecting means to the light shutter means, an optical shutter means for selecting desired light from the plurality of light transmitting means, and brightness and color. Light detecting means for detecting the balance, and correcting means for correcting the brightness and color balance based on the detection data from the light detecting means, wherein the brightness and color balance of the condensing means selected by the light shutter means are adjusted. A rear projector, wherein the brightness and color balance are detected by the light detection means and corrected based on the detected data. 2. The rear projector according to claim 1, wherein one of said light detecting means is provided for a plurality of light transmitting means. 3. The rear projector according to claim 1, further comprising: a mechanism for turning an image by a reflecting mirror in an optical path of image light projected from the projector onto the screen, on a rear side of the reflecting mirror. A rear projector comprising the light collecting means. 4. The rear projector according to claim 3, wherein an optical axis of the light condensing means is arranged to substantially coincide with an optical axis of the image light. 5. A multi-screen rear projector in which a plurality of rear projectors according to claim 1 are arranged to form a multi-screen, wherein each of the rear projectors has at least one light collecting means. ,
A multi-screen rear projector which is mounted on another rear projector side and correlates brightness and color balance among the rear projectors using information on the brightness and color balance of the other rear projector.