JP2509851Y2 - Color projector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a color projector configured to combine red, green and blue image lights using a reflection mirror and a dichroic mirror.

[Prior Art] FIG. 4 shows a liquid crystal color projector including a liquid crystal panel.

In the figure, LA is a white lamp such as a xenon lamp. The white light lw from the white lamp LA is reflected by the total reflection mirror M1 and then the infrared filter and the UV filter FL remove infrared rays and ultraviolet rays, or the white light lw is reflected by a cold mirror (not shown). Then, after the infrared rays and the ultraviolet rays are removed by the UV filter FL, they are incident on the red reflection dichroic mirror DM1.

Red light lr reflected by this dichroic mirror DM1
Is a condenser lens after being reflected by the total reflection mirror M2
The light is collected by C1 and is incident on the red liquid crystal panel LCD1. In the red liquid crystal panel LCD1, the red light lr corresponding to each pixel portion is bright and dark modulated by a red video signal. As a result, red image light lri for obtaining a red image is output from the red liquid crystal panel LCD1.

Further, the cyan light transmitted through the dichroic mirror DM1 is incident on the blue reflection dichroic mirror DM2. The blue light lb reflected by the dichroic mirror DM2 is condensed by the condenser lens C2 and then enters the blue liquid crystal panel LCD2. In the blue liquid crystal panel LCD2, the blue light lb corresponding to each pixel portion is subjected to brightness modulation with a blue video signal. As a result, blue image light lbi for obtaining a blue image is output from the blue liquid crystal panel LCD2.

In addition, green light lg transmitted through the dichroic mirror DM2
Is condensed by the condenser lens C3 and is incident on the green liquid crystal panel LCD3. In the green liquid crystal panel LCD3, the green light lg corresponding to each pixel portion is subjected to brightness modulation with a green video signal. As a result, the green image light lgi for obtaining a green image is output from the green liquid crystal panel LCD3.

The red image light lri output from the red liquid crystal panel LCD1 and the blue image light lbi output from the blue liquid crystal panel LCD2 are incident on the blue reflection dichroic mirror DM3. The image light lri passes through the dichroic mirror DM3, and the image light lbi is reflected by the dichroic mirror DM3. As a result, the image lights lri and lb are emitted from the dichroic mirror DM3.
The combined light of i is output, and this combined light is incident on the green reflection dichroic mirror DM4.

The green image light lgi output from the green liquid crystal panel LCD3 is incident on the total reflection mirror M3, and the green image light lgi reflected by the total reflection mirror M3 is incident on the dichroic mirror DM4. The combined light of the image lights lri and lbi output from the dichroic mirror DM3 passes through the dichroic mirror DM4, and the image light lgi from the total reflection mirror M3 is reflected by the dichroic mirror DM4. As a result, the combined light of the image lights lri, lbi, and lgi is output from the dichroic mirror DM4, and this combined light is projected onto the screen (not shown) via the projection lens LN, and the enlarged color is displayed on the screen. The image is displayed.

Fig. 4 Dichroic mirrors DM1 to DM4 used in the example
And the total reflection mirrors M1 to M3 all adopt the form of surface reflection with respect to the incident light.

For example, FIG. 5 shows a specific structure of the dichroic mirror DM4. In the figure, 11 is a glass substrate,
12 is a dichroic film and 13 is a non-reflective coating. The other dichroic mirrors DM1 to DM3 are similarly configured.

Further, FIG. 6 is a diagram showing a specific configuration of the total reflection mirror M3. In the figure, 21 is a glass substrate and 22 is a reflective film. Note that the total reflection mirrors M1 and M2 are similarly configured.

[Problems to be Solved by the Invention] Generally, when converging light is transmitted through a flat plate such as a dichroic mirror arranged at an inclination, astigmatism and distortion occur. For example, when the convergent light is transmitted through the inclined flat plate as shown in FIG. 7, the convergence point is different between the xy plane and the xz plane as shown in FIGS. 8A and 8B, and an astigmatic difference ΔS occurs.

In the example of FIG. 4, the red image light lri is transmitted through the two dichroic mirrors DM3 and DM4, and the blue image light lbi is 1.
It passes through the individual dichroic mirror DM4. Considering the green image that is the peak of luminosity as a reference, the blue image has a distortion difference of one dichroic mirror, and the red image has a distortion difference of two dichroic mirrors. The deviation is noticeable, and the combined state of the red, green, and blue color images deteriorates.

Conventionally, it has been considered to reduce the thickness of the dichroic mirror to reduce the distortion due to astigmatism and distortion, but it is difficult to reduce the thickness due to the requirement of flatness and the like.

Therefore, the present invention aims to improve the composite state of the red, green and blue color images.

[Means for Solving the Problems] The present invention relates to a color projector in which red, green, and blue image lights are combined by using a total reflection mirror and a dichroic mirror. A total reflection mirror and a dichroic mirror are characterized by using a mixture of the front reflection type and the back reflection type as the total reflection mirror and the dichroic mirror so as to reduce the difference in the number of times of transmission through the total reflection mirror and the dichroic mirror. .

[Operation] For example, if the green reflection dichroic mirror DM4 is of a back reflection type, the green image light is a dichroic mirror.
Since it goes back and forth through the DM4, it substantially passes through two dichroic mirrors. When considering the green image having high visibility as a reference, the blue image has a distortion difference for one dichroic mirror, and the red image has no distortion difference. In other words, it is possible to reduce the difference in distortion between red, green and blue color images without increasing the distortion upper limit (maximum number of transmissions),
It is possible to improve the composite state of each color image.

[Embodiment] An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, parts corresponding to those in FIG. 4 are designated by the same reference numerals, and detailed description thereof will be omitted.

In this example, the green reflection dichroic mirror DM4 is of a back surface reflection type with respect to incident light.

That is, this dichroic mirror DM4 is configured as shown in FIG. In the figure, 31 is a glass substrate, 32 is a dichroic film, and 33 is an antireflection coating. The green image light lgi travels back and forth through the glass substrate 31 of the dichroic mirror DM4 and is combined with the red image light lri and the blue image light lbi which are transmitted through the dichroic mirror DM4.

The present example is configured as described above, and the others are configured similarly to the example of FIG. In this example, the image lights lri, lbi and lgi are combined by the dichroic mirror DM4 as in the example of FIG. 4, and the combined light is projected onto the screen (not shown) via the projection lens LN, so An enlarged color image is displayed on the top.

In this example, the dichroic mirror DM4 is of the back-side reflection type, and the green image light lgi is the dichroic mirror D.
Since it travels back and forth through M4, it is equivalent to passing through two dichroic mirrors. Further, as in the example of FIG. 4, the red image light lri is transmitted through the two dichroic mirrors DM3 and DM4, and the blue image light lbi is one dichroic mirror DM4.
Through.

Therefore, when considering a green image having high visibility as a reference, a blue image has a distortion difference for one dichroic mirror, and a red image has no distortion difference.

Therefore, according to this example, the distortion difference (maximum number of transmissions) due to astigmatism and distortion can be kept the same as in the example of FIG. The condition can be improved.

In the above embodiment, the green reflection dichroic mirror DM4 is of the back surface reflection type, but the total reflection mirror M3 may be of the back surface reflection type with respect to the incident light.

That is, the total reflection mirror M3 is configured as shown in FIG. In the figure, 41 is a glass substrate, 42 is a reflective film,
43 is a non-reflective coating. The green image light lgi is reflected back and forth on the glass substrate 41 of the total reflection mirror M3.

Even if the total reflection mirror M3 is of the back reflection type as described above, the image light lgi is equivalent to passing through the two dichroic mirrors, so that the same effect as that of the example in FIG. 1 can be obtained. it can.

Further, the arrangement of the liquid crystal panels LCD1 to LCD3 in the above-described embodiment is an example, and the arrangement is not limited to this. In short, a dichroic mirror or a total reflection mirror is selected so as to reduce the difference in distortion due to astigmatism and distortion in each color image, and the back reflection type is selected.

Further, in the above-described embodiment, the present invention is applied to a color projector configured by using a liquid crystal panel, but the present invention is applied to other color projectors configured by using, for example, a projection type cathode ray tube. The same can be applied to the projector. In other words, this device
The same can be applied to the case where red, green, and blue image lights are combined using a reflection mirror and a dichroic mirror.

[Advantage of Invention] As described above, according to this invention, a part of the total reflection mirror and the dichroic mirror is of the back reflection type to reduce the difference in distortion between the images of red, green and blue. It is possible to favorably improve the combined state of images.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram of a back surface reflection type dichroic mirror, FIG. 3 is a block diagram of a back surface reflection type total reflection mirror, and FIG. 4 is a conventional example. FIG. 5, FIG. 5 is a configuration diagram of a surface reflection type dichroic mirror, FIG. 6 is a configuration diagram of a surface reflection type total reflection mirror, and FIGS. 7 and 8 are diagrams for explaining astigmatism in the inclined plate. FIG. LA …… White lamp M1 to M3 …… Total reflection mirror FL …… UV filter DM1 …… Red reflection dichroic mirror DM2, DM3 …… Blue reflection dichroic mirror DM4 …… Green reflection dichroic mirror C1 to C3 …… Condenser lens LCD1… … Red liquid crystal panel LCD2 …… Blue liquid crystal panel LCD3 …… Green liquid crystal panel LN …… Projection lens

Claims (1)

(57) [Scope of utility model registration request] 1. A color projector in which red, green, and blue image lights are combined using a total reflection mirror and a dichroic mirror, wherein the red, green, and blue image lights are generated by the total reflection mirror and the dichroic mirror. A color projector, wherein the total reflection mirror and the dichroic mirror are a mixture of a front reflection type and a back reflection type so as to reduce the difference in the number of times of transmission.