JPH0362086A - Projection type color display device - Google Patents

Abstract

PURPOSE:To well prevent the unequal colors of images generated by the nonuniformity in brightness distribution arising from a difference in optical path lengths of respective light rays by disposing 1st and 2nd light quantity regulating means on the optical paths of primary color light rays where the brightness of the central part of an image is low and the brightness of the peripheral part is high as compared to others. CONSTITUTION:The 1st light quantity regulating means 102 which decreases the light quantity of the part corresponding to the peripheral part of the image among the separated primary color light rays and the 2nd light quantity regulating means 100 which increases the light quantity of the part corresponding to the central part of the image are disposed on the optical path of at least one of the primary color light rays by taking the brightness distributions of the respective separated primary color light rays into consideration. The difference in the brightness distributions generated by the difference in the optical path lengths of the respective color light rays is adjusted by combining the light quantity regulating means, such as convex lens, concave lenses and transmitted light quantity regulating means. The unequal colors of the synthesized image are well decreased in this way.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a projection type color display device using a plurality of image forming light valves, and particularly relates to color unevenness correction of the projected image. It is something.

[Conventional technology] Light from a predetermined light source is R (red) and G (green).

The light is separated into the three primary colors of B (blue), and each of these lights is input to each liquid crystal light valve (liquid crystal panel) for R, G, and B to form an image, and then for R, G, and B.

B Various types of color projection display devices (liquid crystal projectors) that combine and project images have been proposed and put into practical use.

Examples of such conventional projection type color display devices include:
There is one shown in FIG. 10 or 11. first 10th
To explain from the conventional example shown in the figure, infrared rays of light emitted from a light source 0 such as a halogen lamp are first filtered by a filter 12. This makes it difficult for the heat from the light source 10 to be transmitted to the front surface.

The light transmitted through the filter 12 enters the blue dichroic mirror 14, where the blue light is separated. The separated blue light is reflected by a reflecting mirror 16 and enters a blue liquid crystal light valve 18 . And here, a blue image is formed.

Next, the light transmitted through the blue glaucroic mirror 14 is
The green light is incident on the green chromic mirror 20, where the green light is separated. The separated green light enters the green liquid crystal light valve 22, where a green image is formed.

Next, the red light that has passed through the green glaucroic mirror 20 is sequentially reflected by the reflecting mirrors 24 and 26 and enters the liquid crystal light valve 28 for red.

And here a red elephant (elephant) is formed.

Next, the B, G, and R images respectively formed by the liquid crystal light bulbs 1B and 22.28 are combined by the one-color combining graphic prism 30, and the combined color image is transferred to the projection lens 32. The image is displayed on the screen 34 by .

Next, a conventional example shown in FIG. 11 will be explained. This conventional example is disclosed in Japanese Patent Laid-Open No. 125791/1983. In the figure, light emitted from a halogen lamp 38 with a reflector 36 is collimated by a condenser lens 40, and parallel light enters a dichroic mirror 42. This dichroic mirror 42 separates the incident light into three primary color lights of R, G, and H.

Among these separated lights, the red light is sequentially reflected by the reflecting mirrors 44 and 46 and enters the liquid crystal light valve 48 for red. Then, a red image is formed here. Next, the green light directly enters the green liquid crystal light valve 50, where a green image is formed. Further, the blue light is sequentially reflected by the reflecting mirrors 52 and 54 and enters the blue liquid crystal light valve 56. A blue image is then formed here.

Next, the R, G, and B images respectively formed by the liquid crystal light valves 48, 50, and 56 are combined by a color compositing graphical prism 58, and the combined color image is projected onto a screen by a projection lens 60. 62.

Compared to a CRT projector such as a television, such a one-night projector can (1) be made smaller and lighter even when optical components are included;

(2) Screen size can be freely selected.

(3) A clear color image can be obtained using a matrix color filter.

(4) Since a powerful light source can be used, high-brightness images can be obtained.

(It is cheaper than the 51CRT type.

It has the following features.

[Problems to be Solved by the Invention] In the conventional projection type color display device as described above, the optical path lengths of the R, G, and B color lights have the following relationship. Note that the distance between the dichroic mirror and the reflecting mirror is equal.

First, in the conventional example shown in FIG. 1O, the optical path of each light is different between the blue dichroic mirror 14 and the liquid crystal light valve 18°22.28. As for the B and G lights, after reflecting or passing through the blue glaucroic mirror 14,
6 or the green glaucroic mirror 20 and enters the liquid crystal light valve 18.22, and the optical path lengths of both are approximately equal. On the other hand, the R light passes through the green glaucroic mirror 14, is further reflected by two reflecting mirrors 24.degree. 26, and enters the liquid crystal light valve 28. Therefore, the relationship between the optical path lengths of R, G, and B multi-lights is as follows: B=G, B<R, and G<R.

Next, in the conventional example shown in FIG. 11, the optical paths of multiple lights are different between the condenser lens 40 and the liquid crystal light pulp 48, 50, 56. After the R and H lights are color-separated by the guichroic mirror 42, they are reflected by 62 reflecting mirrors and respectively enter the liquid crystal light pulp 48.56, so that the optical path of both is The lengths are equal. On the other hand, the G light directly enters the liquid crystal light valve 50 after passing through the guichroic mirror 42.

Therefore, R=B, RA
There is a relationship of G, B>G.

Next, let's consider the luminance distribution of the light output from the light source. The light output from the light source is made as close to parallel light as possible using a reflector, etc., and devised so that the brightness distribution does not change depending on the optical path length. However, since it is not possible to completely parallelize the light beams, in reality, the brightness distribution will differ depending on the optical path length.

For example, in a place where the distance from the light source is short, even if a reflector is used to bring the light rays close to parallel, the luminance distribution will be bright in the center and dark in the periphery, as shown in graph La shown in FIG. 12 fAl. On the other hand, as the distance from the light source increases,
The parallelism of the light beam improves due to diffuse reflection from surrounding walls, etc., resulting in a relatively uniform brightness distribution as shown in graph Lb shown in FIG.

Note that, depending on the configuration of the light source and flutter, the above relationship may be reversed, resulting in a uniform brightness distribution near the light source, and a brightness distribution in areas far from the light source that is bright at the center and dark at the periphery.

Therefore, as mentioned above, if there is an optical path difference between the R, G, and B lights, the brightness distribution of the projected image will be
As shown in the figure, La and Lb are synthesized.

For example, in the conventional example shown in FIG. 10, the graph La is G
, B is the brightness distribution of the light, and the graph Lb is the brightness distribution of the R light. Therefore, the R light becomes stronger than the G and H lights in the peripheral part of the projected image, and conversely, the G and B lights become stronger than the R light in the central part. Therefore, color unevenness occurs in the center and periphery of the image.

Further, in the conventional example shown in FIG. 11, the graph La is the brightness distribution of G light, and the graph Lb is the brightness distribution of R and H lights. Therefore, the R and H lights are stronger than the G lights at the periphery of the projected image, and conversely, the G lights are stronger than the R and B lights at the center.

Therefore, color unevenness will similarly occur in the center and periphery of the image.

The present invention has been made in view of this point, and has an object to effectively prevent color unevenness in images caused by uneven brightness distribution due to differences in optical path lengths of multiple lights from a light source to a light valve. The object of the present invention is to provide a projection type color display device that can perform the following functions.

[Means for Solving the Problems] One aspect of the present invention is to separate the light emitted from a predetermined light source into necessary primary color lights, and to input the light into each image forming means to form an image of each primary color light. in a projection type color display device that forms an image, and then synthesizes and projects these images, a first light amount adjusting means that reduces the amount of light of a portion of the separated primary color light that corresponds to a peripheral area of the image; , a second light amount adjusting means for increasing the light amount in a portion corresponding to the center of the image is arranged on the optical path of at least one primary color light, taking into consideration the luminance distribution of each separated primary color light. This is a characteristic feature.

Another invention is characterized in that the first light amount adjustment means is arranged on the optical path of at least one primary color light in consideration of the luminance distribution of each separated primary color light, and the light amount of a portion corresponding to the center of one image is provided. The present invention is characterized in that the third light amount adjusting means for reducing the amount of light is arranged on the optical path of the other primary color lights in consideration of the luminance distribution of each separated primary color light.

[Function] According to one aspect of the present invention, the first and second light amount adjusting means are arranged on the optical path of the primary color light, which has lower brightness at the center of the image and higher brightness at the periphery compared to the others. . As a result, the brightness distribution of the primary color light is adjusted to be uniform with the brightness distribution of the other primary color lights.

According to another aspect of the invention, the first light amount adjusting means is disposed on the optical path of the primary color light whose brightness is higher in the peripheral part of the image than in the other parts.

Further, the third light amount adjusting means is disposed on the optical path of the primary color light whose brightness is higher in the central part of the image than in the other parts. As a result, the brightness distribution of each primary color light is adjusted to be uniform.

[Examples] Examples of the present invention will be described below with reference to the accompanying drawings. Note that the same reference numerals are used for the same components as in the conventional example described above.

First Embodiment First, with reference to FIGS. 1 to 3, the first embodiment of the present invention will be explained.
An example will be explained. This example is based on the first
The present invention is applied to the conventional example shown in FIG. FIG. 1 is a side view of the first embodiment, and FIG. 2 is a perspective view of its main parts.

In these figures, an infrared cut filter 12 is arranged on the light emission side of the light source 10. On the light transmitting side of this filter 12, a blue glaucroic mirror 14 is provided.
is provided, and this blue graphic mirror 14
A reflecting mirror 16 is disposed on the light reflecting side of the blue liquid crystal light valve 18 and on the incident side of the blue liquid crystal light valve 18 .

Next, on the light transmission side of the blue guichroic mirror 14,
A green glaucroic mirror 20 is provided. A green liquid crystal light valve 22 is disposed on the light reflecting side of the green graphical mirror 20, and a red liquid crystal light valve is disposed on the light transmitting side of the green graphical mirror 20 via reflective mirrors 24 and 26. A light valve 28 is arranged.

Each of the liquid crystal light valves 18, 22, and 28 is arranged on the incident side of the color composition guichroic prism 30, and the projection lens 32.28 is placed on the composite image output side. Screens 34 are arranged respectively.

Next, there is a convex lens 100 on the optical path of the red light that increases the brightness by increasing the amount of red light at the center of the image, and a convex lens 100 that suppresses the amount of red light at the periphery of the image. A transmitted light amount adjusting member 102 that reduces the brightness is provided in each case. Among these, the transmitted light amount adjusting member 102
is constructed by, for example, providing a frame-shaped mask plate as shown in FIG. 4 FAI in a part of a housing (not shown) constituting the red light path.

Next, the overall operation of the first embodiment will be explained with reference to FIG. 3. Light such as halogen lamp,
The infrared rays of the light emitted from the filter 10 are cut by the filter 12. This makes it difficult for the heat from the light source 10 to be transmitted to the front surface.

The light transmitted through the filter 12 is incident on the blue chromic mirror 14, where the blue light is separated. The separated blue light is reflected by the reflection m l 6 and enters the blue liquid crystal light valve 18 . And here, a blue image is formed.

Next, the light transmitted through the blue glaucroic mirror 14 is
The green light is incident on the green guichroic mirror 20, where the green light is separated, and the separated green light is incident on the green liquid crystal light valve 22.

Here, a green image is formed.

Next, the red light that has passed through the green glaucroic mirror 20 is sequentially reflected by the reflecting mirrors 24 and 26 and enters the liquid crystal light valve 28 for red.

At this time, the amount of red light at the center of the image is first increased by the convex lens 100 (see arrow F1 in FIG. 3), and the amount of light at the periphery of the image is reduced by the transmitted light amount adjusting member 102 (see the arrow F1 in FIG. 3). F2.F39). That is, the distribution of red light changes to graph L2 in FIG. 3 (from graph LL of AI to fB of the same figure), and a red image is formed by the red liquid crystal light valve 28 based on this distribution of red light. Ru.

Next, the B, G, and H images respectively formed by the liquid crystal light valves 18, 22, and 28 are combined by a color combining graphical prism 30, and the combined color image is projected onto a screen by a projection lens 32. It is photographed on 34.

As shown in FIG. 3 (C1), the brightness distribution of the blue and green images is represented by the graph L3.The brightness distribution of the red image is represented by the graph L2 as described above.If you compare these, As is clear, the brightness distribution is well approximated in both the central and peripheral parts of the image.Therefore, color unevenness due to non-uniform brightness distribution on the screen 34 is effectively reduced over the entire image. That will happen.

Note that, as shown by ΔL in the figure, if there is an overall level difference between the brightness distributions of R, G, and H images,
The level can be corrected by controlling and adjusting the driving voltages applied to the liquid crystal light valves 18, 22 and 28.

Thereby, the luminance distribution after passing through the liquid crystal light valves 18, 22, and 28 can be made to match well.

Next, referring to FIG. 4, the transmitted light amount adjusting member 102
Other configurations will be explained below. First, let's start with the same figure (A
In the case shown in 1, the border inside the frame is too clear. Therefore, in order to blur the boundaries and give a natural feel,
As shown in fc) and fDl in the same figure, the inside of the frame has a waveform shape.

Next, the degree of color unevenness around the image gradually changes. Therefore, in order to gradually change the light transmittance at the border inside the frame to make it more natural, a frame-shaped filter is used to change the light transmittance from the inside to the outside, as shown in the same figure (El). Gradually decrease the transmittance. In this example,
As shown in FIG. fF), even if a large number of small holes are made in the frame, the amount of transmission can be easily and effectively adjusted.

Next, in order to more naturally prevent one-color unevenness in response to the fact that the light source is spherical, the window portion is made into an elliptical or polygonal shape, as shown in fGl and (Hl) in the same figure.

In addition, instead of using a frame-like shape, it is possible to use a filter-like shape with approximately 100% light transmittance near the center, as shown in Figure (B). You are free to use any other configuration shown in . In addition, an appropriate configuration may be adopted as necessary, and a plurality of configurations may be combined.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIG. In the first embodiment described above, the convex lens 10
0 and the transmitted light amount adjusting member 102 were constructed separately, but in this second embodiment, both are constructed integrally. That is, the transmitted light amount adjusting member 1 is provided on one surface of the convex lens 100.
02 are bonded together, and the cross section of the same figure (A cross section seen along the V-v line of Al in the direction of the arrow is shown in the same figure (8). The thin tube shown in Figure 4 may be used.

<Third Example> Next, referring to FIGS. 6 and 7, the third embodiment of the present invention will be explained.
An example will be explained. In the first and second embodiments described above, a convex lens 100 and a transmitted light amount adjusting member 102 were used, but in this third embodiment, a concave lens is used. Note that the same reference numerals are used for the same components as in the above-described embodiment.

In FIG. 6, only a transmitted light amount adjusting member 102 is provided between the reflecting mirrors 24 and 26 on the optical path of the red light, which suppresses the amount of red light in the periphery of the image and lowers the brightness. Next, the blue glaucroic mirror 14 and the reflecting mirror 1
6 and on the optical path of the blue light, a first concave lens 300 is provided to suppress the amount of blue light at the center of the image and reduce the brightness. Furthermore, a second concave lens 302 is provided between the green glaucroic mirror 20 and the liquid crystal light valve 22 and on the optical path of the green light to suppress the amount of green light in the center of the image and reduce the brightness. It is being

Next, the operation of the third embodiment configured as above will be explained with reference to FIG.
Arrow F4 to Al. As shown at F5, the amount of light in the peripheral areas is reduced. As a result, the brightness distribution of red light becomes graphs L4 to L5 in fAl in the figure.

On the other hand, for blue light and green light, the concave lens 30
Due to the effect of 0.302, the amount of light in the central portion is reduced as shown by arrow F6 in +8) in the figure. As a result, the brightness distribution of blue and the edge becomes graphs L6 to L7 in FIG. 2(B).

As described above, according to the third embodiment, the amount of light is adjusted not only for red light but also for blue and green light, thereby reducing color unevenness.

Fourth Embodiment Next, a fourth embodiment of the present invention will be described with reference to FIG. This fourth embodiment is an application of the present invention to the conventional example shown in FIG. 11, and corresponds to the first embodiment.

In FIG. 8, on the optical path of the red light between the reflecting mirrors 44 and 46, there is a convex lens 400 that increases the amount of red light at the center of the image to increase brightness, and a convex lens 400 that increases the amount of red light at the periphery of the image. A transmitted light amount adjusting member 402 is provided for suppressing and reducing the brightness. Also, reflection fj? On the optical path of the blue light between 52 and 54, there is a convex lens 404 that increases the amount of blue light in the center of the image to increase the brightness, and a convex lens 404 that suppresses the amount of blue light in the periphery of the image to reduce the brightness. A transmitted light amount adjusting member 406 is provided respectively.

According to this embodiment, the same light amount adjustment as in the first embodiment shown in FIG. 3 (Al) is performed for red light and blue light, which have longer optical path lengths than green light.

As a result, the luminance distribution of R, G, and B multi-lights can be made uniform.

<Fifth Embodiment> Next, a fifth embodiment of the present invention will be described with reference to FIG. 9. This fifth embodiment corresponds to the third embodiment, since a concave lens is used in place of the convex lens of the fourth embodiment.

In FIG. 9, between the reflecting mirrors 44 and 46 and on the optical path of the red light, transmitted light amount adjustment members 500 are provided to suppress the amount of red light in the peripheral area of the image and reduce the brightness. Further, between the graphic mirror 42 and the liquid crystal light valve 50 and on the optical path of the green light, there is a concave lens 502 that suppresses the green light in the center of the image and reduces the brightness.
is provided. Furthermore, between the reflecting mirrors 52 and 54 and on the optical path of the blue light, transmitted light amount adjusting members 504 are provided, respectively, to suppress the amount of blue light in the peripheral area of the image and reduce the brightness.

According to this embodiment, the light intensity adjustment shown in FIG. 7(A) is performed for red light and blue light with long optical path lengths, and the light amount adjustment shown in FIG. 7(B) is performed for green light with short optical path lengths. The amount of light is adjusted accordingly. As a result, the luminance distribution of R, G, and B multi-lights can be made uniform.

<Other Examples> Note that the present invention is not limited to the above-mentioned embodiments. The optical path length of each color light changes depending on the arrangement of optical elements such as a guichroic mirror, so it is possible to The type of light amount adjusting means to be provided is determined as appropriate depending on the light amount distribution. Additionally, as mentioned above, depending on the configuration of the light source and flipper, the brightness distribution of each color will be reversed, with a flat distribution throughout the image near the light source, and a distribution where the brightness is high in the center of the image far from the light source. In some cases.

In any case, a transmitted light amount adjustment member is provided in the optical path of colored light with high brightness in the peripheral part of the image, a convex lens is provided in the optical path of colored light with low brightness in the central part of the image, or a convex lens is provided in the optical path of colored light with high brightness in the central part of the image. By providing a concave lens in the optical path,
Ultimately, it is sufficient that the brightness distribution of each color light is made uniform on the screen.

Further, in some cases, the R, G, and B optical path lengths may be different from each other. At this time, the light quantity is adjusted in accordance with the difference in optical path length.

Furthermore, the convex lens, concave lens, and transmitted light amount adjustment member may be formed integrally with other components present in the optical path, and the brightness can be adjusted by optical elements such as reflective mirrors provided in the optical path of each color light. The light amount adjustment characteristics of the transmitted light amount adjusting member etc. may be determined by taking into consideration the influence on the distribution.

[Effects of the Invention] As explained above, according to the present invention, the difference in brightness distribution caused by the difference in optical path length of each color light is adjusted by combining light amount adjustment means such as a convex lens, a concave lens, and a transmitted light amount adjustment member. This has the effect of satisfactorily reducing color unevenness in the composite image.

[Brief explanation of drawings]

FIG. 1 is a side view showing the configuration of the first embodiment of the present invention, and FIG.
3 is a graph showing the operation of the first embodiment, FIG. 4 is an explanatory diagram showing various aspects of the transmitted light amount adjusting member in the embodiment, and FIG. The figure is an explanatory diagram showing the second embodiment, Fig. 6 is a side view showing the third embodiment, Fig. 7 is a graph showing the operation of the third embodiment, and Fig. 8 is a side view showing the fourth embodiment. 9 is a side view showing the fifth embodiment, FIGS. 10 and 11 are side views each showing a conventional device, and FIG. 12 is a graph showing the luminance distribution of each color light caused by the difference in optical path length. . 10... Light source, 12... Filter, 14... Blue glaucroic mirror, 16.24.26.44°46
．． 52.54...Reflector, 18.22.2848.5
0.56...Liquid crystal light valve (image forming means), 2
0... Green guichroic mirror 32.60... Projection lens, 34.62... Screen, 100,40
0.404...Convex lens (second light amount adjustment means),
102,402.406,500.504...Transmitted light amount adjustment member (first light amount adjustment means), 300.3
02.502... Concave lens (third light amount adjustment means). Figure 3 Figure 2 Figure 8 Figure 1/ Figure 2 Figure O

Claims (2)

[Claims] (1) Projection in which light emitted from a predetermined light source is separated into necessary primary color lights, which are incident on each image forming means to form an image of each primary color light, and then these images are combined and projected. type color display device, a first light amount adjusting means for reducing the light amount of a portion of the separated primary color light corresponding to the peripheral portion of the image, and a first light amount adjusting means for increasing the light amount of the portion corresponding to the center portion of the image. 1. A projection type color display device, characterized in that a second light amount adjusting means is arranged on an optical path of at least one primary color light in consideration of the luminance distribution of each separated primary color light. (2) Projection in which light emitted from a predetermined light source is separated into necessary primary color lights, which are incident on each image forming means to form an image of each primary color light, and then these images are combined and projected. In the type color display device, the first light amount adjusting means for reducing the light amount of a portion of the separated primary color light corresponding to the peripheral area of the image is configured to at least consider the luminance distribution of each separated primary color light. A third light amount adjusting means is placed on the optical path of one primary color light and reduces the light amount in a portion corresponding to the center of the image. A projection type color display device characterized by being placed on an optical path.