JP2002277959A - Tri-prism type projection display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tri-prism type projection display which improves video contrast and quality. SOLUTION: The projection display 3 includes a polarization mode converting device 31 which modulates a 1st color 21 from P polarization to S polarization, a polarization beam splitting prism which splits colors according to a polarization mode, reflects the 1st color modulated to the S polarization orthogonally, and transmits 2nd and 3rd colors 22 and 23 of the P polarization, a 1st bicolor beam splitting prism 33 which is installed in the direction of reflection of the 1st color of the S polarization and transmits only the 1st color, a 2nd bicolor beam splitting prism 35 which is provided in the direction of projection of the 2nd and 3rd colors of the P polarization and splits the 2nd color and the 3rd color, and three optical modulators 34, 36, and 37 which are fitted in the projection direction of the 2nd and 3rd colors and reflect the colors and/or selectively modulate the polarization style.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection display, and more particularly to a projection display of a single-lens reflective light modulator that performs reflection projection using three prisms (triprisms).

[0002]

2. Description of the Related Art Three primary colors (red,
(Green, blue) to obtain a desirable display effect, a conventional single-lens projection display uses a light beam 10 generated by an illumination device in a liquid crystal display as shown in FIG.
Is processed, and the light beam 10 that has undergone the processing is further
1, and the highest quality image is projected. The light beam 10 becomes a white light when it overlaps the first color 101, the second color 102, and the third color 10.
Contains three. In addition, a conventional projection display 1
Are a first polarization selector 12, a polarization beam separation prism 13, a two-color beam separation prism 14, a first light modulator 15, a second light modulator 16, a third light modulator 17, and a second polarization A selector 18 and a polarizing plate 19 are provided.

The polarization selectors 12, 18 are Color
ColorSelect ^™ Fi from Link Company
It is possible to modulate the polarization form of a predetermined color (for example, green) without affecting the polarization form of other colors.

The polarization beam splitting prism 13 can vertically reflect the S-polarized color and directly transmit the P-polarized color, and the dichroic beam splitting prism 14 can selectively reflect or reflect different colors. Pass through, pass through a first color 101 and reflect a second color 102. The polarization selectors 12 and 18 have a function of modulating the polarization form of a predetermined color, and taking the above-mentioned prior art as an example, the first and second polarization selectors 12 and 18 use the third color 103 for polarization. Shape modulation is possible, and P
The light is modulated to be polarized, and the polarizer 19 transmits the P-polarized color and makes it enter the lens 11 to absorb the S-polarized color.

[0005] As shown in FIG.
Is incident from the first polarization selector 12, only the third color 103 is modulated into P polarization, and the other first and second colors 101 and 102 are still maintained in S polarization,
When the first color 101 of the S-polarized light reaches the polarization beam splitting prism 13, it is vertically reflected by the dichroic beam splitting prism 14 and transmitted through the dichroic beam splitting prism 14 to form the first light 101. The light is incident on the modulator 15. Under the state where the first optical modulator 15 is in the open state, the first color 101 of the S polarization is reflected by being modulated to the P polarization and transmitted through the dichroic beam splitting prism 14, At this time, it is affected by the P polarization characteristic of the beam splitting prism, and most (about 90%) of the P polarization first color 1
01 passes through the polarization beam splitting prism 13 and further passes through the second polarization selector 18 and the polarizing plate 19 to the lens 11.
And a small portion (about 10%) of P-polarized first color 1
01 becomes the polarization leak light 104 and becomes the first polarization selector 12
Is reflected by This is the optical path of the first color 101.

For the same reason, the second color 102 of the same S-polarized light passes through the first polarization selector 12 and is reflected by the polarized-light beam splitting prism 13 toward the two-color beam splitting prism 14. Since the second light modulator 16 is irradiated from the reflection of the color beam splitting prism 14 in the vertical direction to the second light modulator 16, the second color 102 of all S polarizations becomes the P polarization under the state where the second light modulator 16 is opened. And then reflected back to the dichroic beam splitting prism 14, where most of the P-polarized second color 102 passes through the polarizing beam splitting prism 13 and finally a second polarization selector. 18, and enters the lens 11 through the polarizing plate 19. On the other hand, a small portion of the second color 102 of the P polarization forms another polarization leakage light 105 and is reflected toward the first polarization selector 12. That is, the polarization form of the second collar 102 is the same as that of the first collar 101, most of which is projected on the lens 11, and a small part forms polarized light leaks 104 and 105, and is directed in the direction perpendicular to the lens 11. The reflected light, and thus the resulting polarization leakage light 104 and 105, does not affect the image quality of the lens 11.

FIG. 6 shows the optical path of the third color 103 in the conventional single-lens projection display. The third color 103 of the conventional single-lens projection display 1 is the first color. When transmitted through the polarization selector 12, the original S-polarized light is modulated into P-polarized light. However, the third color 103 is approximately 90% due to the influence of the P-polarized light characteristic of the beam separation prism. % Passes through the polarized beam splitting prism 13 to reach the third optical modulator 17, and the other approximately 10% of the third color 103 is reflected and projected on the two-color beam splitting prism 14 to form a so-called polarized wave. Light leakage 106 is formed. The polarization leaked light 106 may enter the first light modulator 15 and / or the second light modulator 16 depending on the selection range of the third color 103 wavelength. According to the traveling path of the first color 101 or the second color 102, they are reflected together and projected toward the lens 11, and the polarizing plate 19 can absorb only one kind of polarized light. Since it is provided so as to absorb S-polarized light, the light leakage formed by the third color 103 of P-polarized light is not absorbed, and is directly projected on the lens 11 to reduce the image contrast and the imaging effect. This results in poor image quality of the conventional single-lens display 1.

As shown in FIG. 6, as described above, only the third color 103 of about 90% of P polarization is projected on the third optical modulator 17 due to the influence of the characteristics of the beam separation prism, and When the optical modulator 17 is open, these third colors 103 are modulated from P polarization to S polarization, and the polarization beam separating prism 13 reflects the S polarization color. The third color 103 whose form has been modulated is projected vertically onto the second polarization selector 18 and the polarizing plate 19 and further enters the lens 11. When the third optical modulator 17 is closed, the third collar 103 is not projected onto the lens 11, but the third collar 103 exhibits P polarization, and the third color 103 has the third polarization. Similarly, the color 103 is reflected by the polarization beam splitting prism 13 in the P-polarized state, and is affected by the characteristics of the beam splitting prism.
90% goes to the left in Figure 6 and about 10%
Is vertically reflected by the second polarization selector 18 in the upper part of FIG. 6 to form a polarized light leak 107. Since the polarized light leaked 107 of the P polarization is not absorbed by the polarizing plate 19, the unequally reflected P light is reflected. The polarization leakage light 107 of the polarized light is directly projected on the lens 11, and the third color 103 which is weak but should not appear on the lens 11 appears, which has an unfavorable effect on the image quality of the projection display 1. .

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the conventional single-lens projection display, and an object of the present invention is to improve the image contrast and quality. To provide a new and improved tri-prism projection display.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a method of receiving a light beam including a first color, a second color and a third color in a P-polarized form. A polarization form conversion device for modulating the first color from P-polarization to S-polarization in a projection display for projecting a light beam to a lens disposed in an orthogonal direction after spectral processing;
A polarization beam separation prism that separates colors according to the polarization mode, reflects the first color modulated into the S polarization in the orthogonal direction, and transmits the second and third colors of the P polarization;
A first dichroic beam splitting prism that is installed in the direction in which the first color of polarization is reflected and transmits only the first color, and projects the second and third colors of P polarization. A second dichroic beam separating prism for separating the second color and the third color, the prisms being respectively mounted in a direction in which the first, second and third colors project, And three light modulators for reflecting the color and / or selectively modulating the polarization form.

The polarization mode conversion device includes a polarization plate for P polarization for purifying the polarization mode of the light beam, and a polarization selector for modulating the first color of P polarization to S polarization. A polarization selector that can modulate the polarization form of the first color between the polarization beam splitting prism and the lens, and a P selector between the polarization selector and the lens. It is more preferable to provide a polarizing plate capable of absorbing the polarization color.

According to the present invention having the above-described structure, when each optical modulator is in an open or closed state, all the polarization leakage light generated by the P polarization during operation is directed in a direction orthogonal to the direction reaching the lens. Since it is refracted or absorbed by the polarizer before reaching the lens, it does not penetrate the lens and has no adverse effect on imaging.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
Preferred embodiments of a tri-prism projection display according to the present invention will be described in detail. In this specification and the drawings, components having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted. As shown in FIG. 1, the projection display 3 according to the present embodiment receives a light beam 2, appropriately processes the light beam 2, and then projects the light beam 2 onto a lens 20 installed vertically. The light beam 2 includes a first color 21 of green, a second color 22 of red, and a third color 23 of blue.
All 1, 2, and 23 exist in the form of P-polarized light, and are sent to the lens 20 in the form of S-polarized light.

The projection display 3 according to the present embodiment.
Is a polarization form conversion device 31, a polarization beam separation prism 3
2, a first two-color beam separation prism 33, a first light modulator 34, a second two-color beam separation prism 35, a second light modulator 36, a third light modulator 37,
It includes a polarization selector 38 and a polarizing plate 39.

The polarization form converter 31 is used to modulate the polarization form of the first color 21 of the light beam 2, modulates the P-polarization into the S-polarization, and modulates the polarization of the light beam 2. P-polarization polarizing plate 311 for purifying the form and first P-polarization
And a polarization selector 312 that modulates the color 21 to S polarization. The polarization form converter 31 can be implemented in various forms.
The present invention is not limited to only those disclosed in the present embodiment.

The polarization beam splitting prism 32 has a first color 21 and second and third colors 2 having different polarization forms.
2, 23 can be separated. In the present embodiment, the S-polarized first color 21 is vertically reflected away from the lens 20, and the P-polarized second and third colors 22 and 23 are transmitted. I have.

The first dichroic beam splitting prism 33 is arranged in parallel with the polarized beam splitting prism 32 and is provided on the side remote from the lens 20. Reflects light rays. In the present embodiment, the first two-color beam splitting prism 33 transmits the green first color 21 and reflects the second and third colors 22 and 23.

The first optical modulator 34 is arranged upright in parallel with the first dichroic beam splitting prism 33, and is provided on the side remote from the polarized beam splitting prism 32, and has a color polarization form. Can be modulated, and in the open state, the first S-polarized light projected on the first optical modulator 34 can be modulated.
Is modulated to the first color 21 of P polarization, and when the first optical modulator 34 is closed, the first color 21 of S polarization is modulated.
Of the color 21 is reflected without modulation.

The second dichroic beam splitting prism 35 is provided on the optical path of the P polarization color above the polarization beam splitting prism 32, and transmits or reflects light according to the color. When the third colors 22 and 23 simultaneously reach the second two-color beam splitting prism 35, the red P-polarized second color 22 can be transmitted and the blue P-polarized third color 23 is reflected. Is done.

The second light modulator 36 is mounted above the second dichroic beam splitting prism 35, and
And selectively modulates its polarization mode at the same time. The function thereof is the same as that of the first optical modulator 34, and the description thereof will not be repeated.

The third light modulator 37 is located on the left side of the second dichroic beam splitting prism 35, and reflects the third color 23 and / or selectively modulates the polarization form. Its function is equivalent to that of the first light modulator 34.

The polarization selector 38 is provided in parallel between the polarization beam splitting prism 32 and the lens 20, and can modulate the first color 21 of P polarization into S polarization.

The polarizing plate 39 is interposed between the polarization selector 38 and the lens 20, and is used to absorb the P-polarized color.

As shown in FIG. 1, the first color 2 of the P polarization
1 passes through the polarization selector 312 and the first
Is modulated to a color 21 of The first color 21 is incident on the first dichroic beam splitting prism 33 in the vertical direction by reflection on the polarized beam splitting prism 32. Since the first two-color beam splitting prism 33 transmits the first color 21 of green, the first color 21 of S polarization passes therethrough and is projected on the first light modulator 34. When the first optical modulator 34 is open, the first dichroic beam splitting prism reflects the S-polarized first color 251 and modulates it into the P-polarized first color 21. 33,
Although the first color 21 is modulated to P polarization, it is still green, so that it can pass through the first two-color beam splitting prism 33 and is projected on the polarized beam splitting prism 32, and further has the characteristics of the beam splitting prism. Accordingly, the first color 21 of P polarization of about 90% is transmitted through the polarization beam splitting prism 32 and is modulated by the polarization selector 38 into S polarization. Thereafter, the image is projected and received on the lens 20 via the polarizing plate 3 as the first color 21 of S polarization. On the other hand, approximately 10
% First polarization 21 is first polarization leakage light 211.
Is formed and projected toward the polarization conversion device 31. That is, since the projection direction of the first polarized light 211 is orthogonal to the direction in which the light advances to the lens 20, the first polarized light 211 does not adversely affect the imaging of the lens 20.

As shown in FIG. 2, when the first optical modulator 34 is closed, the first color 21 of the S-polarized light originally refracted from the polarized beam splitting prism 32 is
The light passes through the first dichroic beam splitting prism 33 in the same polarization form. Further, the light passes through the polarization beam splitting prism 32 and is reflected in the incident direction of the light beam 2. Since this direction of reflection is perpendicular to the direction of projection onto the lens 20, the first color 21 of refraction has little effect on the projected image.

As shown in FIG. 3, the second and third collars 2
When 2 and 23 reach the polarized beam splitting prism 32,
Since it is incident in the form of P polarization, about 90% of P
The first and second polarized colors 22 and 23 pass through the polarized beam splitting prism 32 and project toward the second dichroic beam splitting prism 35. However, due to the characteristics of the beam splitting prism, the second and third P-polarized lights of about 10% still remain.
When the colors 22 and 23 reach the polarized beam splitting prism 32, they are orthogonally reflected in the direction of the first two-color beam splitting prism 33 to form the second polarized light leaking light 24, and the second polarized light leaking light 24 is formed. Since 24 includes the second and third colors 22 and 23 of red and blue, it cannot pass through the first two-color beam splitting prism 33 that transmits only the green color. Accordingly, the second and third colors 22 and 23 reflected by the first dichroic beam splitting prism 33 are reflected again in a direction orthogonal to the direction toward the lens 20 (upward in FIG. 3). This second polarized light leakage 24 also does not adversely affect the hue of the projected image.

On the other hand, the 90% second and third colors 22, 23 transmitted through the polarized beam splitting prism 32 are the second colors 22, 23.
When the light reaches the two-color beam separation prism 35, the light is separated into a second color 22 transmitting therethrough and a third color 23 reflected thereby. Among them, the P-polarized red second color 22 is transmitted through the second dichroic beam separating prism 35 and directly projected to the second optical modulator 36, and the P-polarized blue third color 23 is the second color. The light is orthogonally reflected leftward in FIG. 5 by the two dichroic beam splitting prisms 35 and projected toward the third light modulator 37. Then, when the second light modulator 36 is open, the P-polarized second collar 22 is reflected by the second light modulator 36 and the polarization form is modulated. That is, the S-polarized second color 22 after reflection is entirely transmitted through the second two-color beam splitting prism 35 and projected to the polarized beam splitting prism 32. Thereafter, all the light is projected to the polarization selector 38 and the polarizing plate 39 in the orthogonal direction, and a very small amount of the impure P-polarized color in the second color 22 is absorbed by the polarizing plate 39, and finally, all the light is transmitted to the lens 20. Projected.

Similarly, when the third light modulator 37 is open, the third color 23 of the P polarization projected on the third light modulator 37 is the third color 23 of the S polarization.
Is modulated. Thereafter, the whole is reflected to the second dichroic beam splitting prism 35. At this time, the third collar 23
Still has a blue color reflected by the second dichroic beam splitting prism 35, so that the S-polarized third color 2
3 is reflected and projected to the polarization beam splitting prism 32. Thereafter, the polarization selector 38 and the polarization plate 39
And is projected on the lens 20 via.

More specifically, when the second and third optical modulators 36 and 37 are in an open state, the second and third collars 22 and 23 that have entered the P-polarized light are simply shown in FIG. Only the second polarization leakage light 24 which is emitted to the upper right side of
The first collar 21 incident in the form of S-polarization produces a first polarization leakage light 211 that emerges downward in FIG. Since the directions of the first and second polarized light leaks 211 and 24 are all orthogonal to the direction of the lens 20, there is no undesirable effect on the projected image.

As shown in FIG. 4, when the second optical modulator 36 is closed, the P-polarized second color 22 originally passing through the second dichroic beam splitting prism 35 becomes polarized. Is not modulated and still passes through the dichroic beam splitting prism 35 in the form of P-polarized light,
To project. For the same reason, approximately 90% of the P-polarized second color 22 passes through the polarized beam splitting prism 32 and is emitted in the incident direction of the light beam 2. Therefore, most P-polarized second collars 22 do not adversely affect lens 20. Other 10% P-polarized second color 22
Is reflected by the polarization beam splitting prism 32 and the lens 2
The third polarization leakage light 25 of the zero direction is formed,
Since the polarizing plate 39 for absorbing the P-polarized light is attached between the third polarized light leaking light 25 and the polarized beam splitting prism 32.
Is completely absorbed by the polarizing plate 39 and does not pass through the lens 20.

Similarly, when the third optical modulator 37 is closed, the P-polarized third color 23 is directly reflected by the dichroic beam splitting prism 35, and is reflected by the polarized beam splitting prism 32. Project. After that, most of the P-polarized third collar 23 exits in a direction orthogonal to the lens 20, and a small portion of the P-polarized third collar 23 forms a third polarized light leak 25 directed to the lens 20. Then, the light is absorbed by the polarizing plate 39 and cannot reach the lens 20. The opening and closing of each of the light modulators 34, 36, 37 is controlled according to the demand for video color. Therefore, each optical modulator 3
Although the opening and closing of the optical modulators 4, 36 and 37 are not constant, when the optical modulators 34, 36 and 37 are open or closed, all the polarization leakage light generated by the P-polarization during the operation is directed to the lens 20. Because the light is refracted in the direction perpendicular to the direction or absorbed by the polarizing plate 39 before reaching the lens 20.
It does not pass through the lens 20 at all. In the present invention, a member for enhancing the contrast, for example, a quarter wave plate may be provided between each of the light modulators 34, 36, 37 and each of the adjacent two-color beam splitting prisms 33, 35.

While the preferred embodiment of the triprism type projection display according to the present invention has been described with reference to the accompanying drawings, the present invention is not limited to this example. It is clear that a person skilled in the art can conceive various changes or modifications within the scope of the technical idea described in the claims, and those modifications naturally fall within the technical scope of the present invention. It is understood to belong.

[0033]

As can be seen from the above description, the present invention utilizes a combination of a polarization beam splitting prism and a two-color beam splitting prism to realize a projection display using a projection display.
The drawback that a part of the polarized light leakage in which the P polarization is generated is projected on the lens can be surely improved. Further, most of the polarized light leakage is refracted or reflected in a direction different from the direction toward the lens, so that the image contrast and quality can be surely enhanced.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an arrangement of an embodiment of the present invention and an optical path of a first color when a first optical modulator is in an open state.

FIG. 2 is an explanatory diagram showing an optical path of a first color when the first light modulator in FIG. 1 is in a closed state.

FIG. 3 is an explanatory diagram showing optical paths of first and second colors when the second and third light modulators in FIG. 1 are open.

FIG. 4 is an explanatory diagram showing optical paths of first and second colors when the second and third light modulators in FIG. 1 are closed.

FIG. 5 is an explanatory diagram showing a configuration and arrangement of a conventional single-lens projection display and optical paths of first and second colors of S polarization.

FIG. 6 is an explanatory diagram illustrating an optical path of a third color of P polarization in FIG. 5;

[Explanation of symbols]

 Reference Signs List 2 light beam 20 lens 21 first color 211 first polarized light leakage 22 second color 23 third color 24 second polarized light leakage 25 third polarized light leakage 3 projection display 31 polarization form conversion device 311 Polarizer 312 Polarization selector 32 Polarization beam separation prism 33 First two-color beam separation prism 34 First light modulator 35 Second two-color beam separation prism 36 Second light modulator 37 Third light modulator 38 Polarization selector 39 Polarizing plate

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02F 1/13 505 G02F 1/13 505 H04N 9/31 H04N 9/31 C F-term (Reference) 2H042 CA06 CA07 CA14 CA17 2H049 BA05 BA08 BA43 BA47 BB03 BC22 2H088 EA12 HA18 HA20 HA23 MA01 MA02 5C060 BA03 BB13 BC05 GA01 GB06 HC10 JA17 JB06

Claims (4)

[Claims] 1. A light beam including a first color, a second color, and a third color in a P-polarized form enters, is subjected to spectral processing, and is then projected onto a lens installed in an orthogonal direction. A polarization mode conversion device for modulating the first color from P-polarization to S-polarization;
A polarization beam separation prism that separates colors according to the polarization mode, reflects the first color modulated into the S polarization in the orthogonal direction, and transmits the second and third colors of the P polarization;
A first dichroic beam splitting prism that is installed in the direction in which the first color of polarization is reflected and transmits only the first color, and projects the second and third colors of P polarization. A second dichroic beam separating prism for separating the second color and the third color, the prisms being respectively mounted in the direction in which the first, second and third colors are projected, A three light modulator for reflecting and / or selectively modulating the polarization form of the color. 2. The polarization mode conversion device according to claim 1, wherein the polarization mode conversion device comprises a P-polarization polarizer for purifying the polarization mode of the light beam, and a polarization selector for modulating the first color of the P-polarization to S-polarization. The tri-prism projection display according to claim 1, wherein the projection display is provided. 3. The apparatus according to claim 1, further comprising a polarization selector provided between said polarization beam splitting prism and said lens, said polarization selector being capable of modulating the polarization form of said first color.
Or the triprism type projection display according to 2. 4. The triprism type projection according to claim 3, wherein a polarizing plate capable of absorbing a P-polarized color is further provided between the polarization selector and the lens. display.