JPH05224172A - Liquid crystal projection type display device - Google Patents

Abstract

PURPOSE:To improve the brightness on a screen by increasing the availability of light and to reduce a brightness irregularity, a color irregularity, and a picture element deviation on the screen as necessary. CONSTITUTION:The projection light 15 outputted from a light source 14 is separated by a polarized light separating element 72 into two kind of polarized light components 15p and 15s whose polarization directions cross each other at right angles and they are separated by color separating elements 74 and 92 into light beams of R, G, and B respectively; and light crystal light valves 86-90, and 104-108 for R, G, and B impose intensity modulation on the light beams, color composing elements 110 and 120 put the beams of R, G, and B together by polarized light components, and a polarized light composing element 116 composes the light of the polarized light beams, so that the light is projected on the screen through a projection lens 40. The polarized light beams 15p and 15s of the projection light 15 are both utilized to increase the availability of the light. The length of the optical path where the polarized light beams 15p and 15s reach the light valves is equalized to the length of the optical path where the light modulated by the liquid crystal light valves reaches the projection lens 40 and then the optical path lengths become equal, thereby reducing the brightness irregularity, color irregularity, and picture element deviation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention decomposes light from a light source into three primary color lights of R (red), G (green) and B (blue) with a color separation element, and liquid crystals for R, G and B The light intensity is modulated by electrically changing the polarization direction of the light using a light valve, then color combination is performed by a color synthesizing element and screen is passed through the projection lens.
The present invention relates to an improvement of a liquid crystal projection display device that is adapted to project on a screen.

[0002]

2. Description of the Related Art Conventionally, this type of liquid crystal projection type display device has been constructed as shown in FIG. That is, the projection light (natural light of random polarization) 15 from the light source 14 formed by the metal halide lamp 10 and the reflector 12 is converted into R by the color separation element 20 including the dichroic mirrors 16 and 18.
Disassembled into three primary color lights of G and B, and condenser lenses 22 and 2
Liquid crystal light valve 2 for R, G, B via 4, 26
8, 30 and 32, and the light modulated here is color-synthesized by a color synthesizing element 38 composed of dichroic mirrors 34 and 36, and screened by a projection lens 40 (not shown).
I was projecting on top.

At this time, the liquid crystal light valve 28 is shown in FIG.
As shown in FIG.
A polarizing plate (polarizer) 44 provided on the light source 14 side and a polarizing plate (analyzer) 46 provided on the screen side of the liquid crystal panel 42, the projection output from the light source 14 by the polarizing plate 44. Of the light 15 (for example, vertically polarized light 15 p and natural light that can be decomposed into horizontally polarized light 15 s), only the polarized light 15 s (for example, S polarization) that is the same as the polarizing plate 44 is projected on the liquid crystal panel 42. The polarizing plate 46 is
The polarization direction is arranged perpendicular to or parallel to the polarization direction of the polarizing plate 44 (vertical in FIG. 3), and the light modulated by the liquid crystal panel 42 (for example, P polarized light) is transmitted. The other liquid crystal light valves 30 and 32 were also configured similarly to the liquid crystal light valve 28. 47 is a cold mirror, 48 and 49 are mirrors,
Reference numeral 50 is a cold filter.

[0004]

However, the conventional example shown in FIG. 2 has a problem that the light utilization rate is small and it is difficult to increase the brightness on the screen. That is, since only the polarized light 15s (for example, S-polarized light) of the projection light 15 output from the light source 14 that is the same as the polarization direction of the polarizing plate 44 is projected on the liquid crystal panel 42, the polarization direction is the polarizing plate 44. The polarized light 15p (for example, P-polarized light) orthogonal to the polarization direction is not available, and the light utilization rate is 50.
% Or less, and it is difficult to increase the brightness on the screen.

In order to solve such a problem, as shown in FIG. 4, two projection devices (projectors) 52 and 54 equipped with the optical system shown in FIG. 2 are arranged in parallel, and these projection devices 52, The projection light 56 and 58 from the screen 54
Some projectors are arranged so that they are projected on top of each other on the screen 0 to increase the brightness on the screen 60.
Since 54 is required, it is necessary to prepare a large space for installation and it is expensive, and it is difficult to align the pixels on the screen 60, and uneven brightness and uneven color due to trapezoidal distortion are likely to occur. there were.

In order to solve the above problems, the present applicant has already proposed a device as shown in FIG. That is, two projection devices 66 and 68 that output projection lights 62 and 64 whose polarization directions are orthogonal to each other are provided, and one of these projection lights 62 and 64 (for example, the projection light 62 that is P-polarized light) has a high transmittance. A polarizing beam splitter 70 is provided for transmitting the other light (for example, S-polarized projection light 64) with a high reflectance and synthesizing the two in the same direction to output the polarized light beam splitter 70. Projection light 62 to be combined and output
a and 64a are projected on the screen 60 to reduce the uneven brightness and uneven color due to the trapezoidal distortion, and the screen 6
The brightness above 0 could be increased.

However, the apparatus shown in FIG. 5 has some problems as follows. Ie, still 2
Since the projection devices 66 and 68 are needed, the space required for installation must be wide. In addition, the projection light 6 which is P-polarized light from the projection device 66.
2 and the S-polarized projection light 64 from the projection device 68 are combined on the screen 60, the optical distance from the light source to the liquid crystal panel and the distance from the liquid crystal panel to the projection lens are between the projection devices 66 and 68. If the respective optical distances are not kept in a constant relationship with each other, uneven brightness, uneven color, pixel deviation, etc. occur on the combined screen on the screen 60. Therefore, uneven brightness, uneven color, and pixel deviation are prevented. There is a problem that the adjustment for doing this becomes complicated.

The present invention has been made in view of the above-mentioned problems, and provides a liquid crystal projection display device capable of increasing the utilization rate of light and not requiring a large space for installing the device. It is an object of the present invention to further prevent luminance unevenness, color unevenness, and pixel shift from occurring on the screen as needed.

[0009]

A liquid crystal projection display device according to the present invention includes a light source, a polarization light decomposing element for decomposing light from the light source into two types of polarized light having polarization directions orthogonal to each other, and the polarization light decomposing element. A color separation element that decomposes each of the two types of polarized light decomposed by the photolytic element into three primary color lights of R, G, and B, and each of the three primary color lights of R, G, B resolved by this color separation element. A liquid crystal light valve for R, G, and B that modulates the light intensity, and a color combining element that combines the three primary color lights of R, G, and B modulated by these R, G, and B liquid crystal light valves for each polarization component And a polarized light combining element for combining the two types of polarized light combined by these color combining elements, and a projection lens for projecting the light combined by the polarized light combining element onto a screen. It is what

Then, if necessary, in order to reduce unevenness in brightness, unevenness in color and pixel shift due to the difference in optical distance,
The two types of polarized light separated by the polarized light decomposition element have equal optical path lengths to the R, G, B liquid crystal light valves through the color separation element, and are modulated by the R, G, B liquid crystal light valve. The polarized light decomposing element, the color separating element, the R, G, B liquid crystal light valve, and the color synthesizing element so that the optical paths of the generated light through the color synthesizing element and the polarized light synthesizing element reach the projection lens are equal to each other. , A polarized light combining element and a projection lens are arranged.

[0011]

The function of the polarized light decomposing element is two kinds of polarized light whose polarization directions are orthogonal to each other (for example, P polarized light and S polarized light).
Disassemble into. The two types of polarized light are separated into the three primary color lights of R, G and B by the corresponding color separation elements, and then input to the R, G and B liquid crystal light valves. The R, G, B three primary color lights whose light intensities are modulated by the R, G, B liquid crystal light valves are color-synthesized by a color synthesizing element, and then two kinds of polarized light are synthesized by a polarized light synthesizing element. Project on the screen through the projection lens.

As described above, the light was decomposed by the polarized light decomposing element.
Each type of polarized light is color-separated, modulated by a liquid crystal light valve, then color-combined, polarized-light combined by a polarized-light combining element, and projected onto a screen via a projection lens. It is possible to use two types of polarized light whose polarization directions are orthogonal to each other. For this reason,
The brightness on the screen can be increased.

Further, the two types of polarized light separated by the polarized light decomposing element have equal optical path lengths to the R, G, B liquid crystal light valves through the color separating element, and R, G,
When the respective elements are arranged so that the light paths modulated by the B liquid crystal light valve reach the projection lens through the color synthesizing element and the polarized light synthesizing element, they are equal to each other,
It is possible to reduce uneven brightness, uneven color, and pixel shift due to the difference in optical distance.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the projection type display device according to the present invention will be described below with reference to FIG. 1, the same parts as those in FIG. 2 are designated by the same reference numerals. In FIG. 1, 14 is a light source, and this light source 14 is composed of a metal halide lamp 10 and a reflector 12. Reference numeral 47 is a cold mirror, 48 and 49 are mirrors, 50 is a cold filter, and 51 is a double-sided reflection mirror.

Reference numeral 72 denotes a polarization beam splitter as a polarized light decomposing element. The polarization beam splitter 72 has two types of polarized light beams 15p whose polarization directions are orthogonal to each other for the projection light 15 output from the light source 14. It is configured to be disassembled into 15s. One polarized light 15p is polarized light having a vertical polarization direction (P-polarized light) and is transmitted through the polarization beam splitter 72 with high transmittance, and the other polarized light 15s is polarized light having a horizontal polarization direction (S). Polarization), the polarization beam splitter 72
Reflects with high reflectance.

74 is a dichroic mirror-76 and 7
The color separation element 74 is composed of eight color separation elements 74. The color separation element 74 decomposes the polarized light 15p into three primary color lights of R (red), G (green), and B (blue), and condenses these lights into condenser lenses 80 and 82. ,
Liquid crystal light valves 86, 8 for R, G, B via 84
It is configured to input to 8 and 90. A color separation element 92 is composed of dichroic mirrors 94 and 96. The color separation element 92 converts the polarized light 15s into R.
(Red), G (green), and B (blue) are separated into three primary color lights, and these lights are passed through condenser lenses 98, 100, and 102 for R, G, and B liquid crystal light valves 104, 106, and 1.
08 is configured to be input.

Reference numeral 110 denotes a color synthesizing element composed of dichroic mirrors 112 and 114.
Are the liquid crystal light valves 86, 88, 9 for R, G, B
The R, G, and B lights modulated by 0 are color-combined and input to one side of the polarization beam splitter 116 as a polarization light combining element. Reference numeral 120 denotes a color synthesizing element including dichroic mirrors 122 and 124. The color synthesizing element 120 colors the R, G, B lights modulated by the R, G, B liquid crystal light valves 104, 106, 108. The light beams are combined and input to the other side of the polarization beam splitter 116. A projection lens 40 is provided on the output side of the polarization beam splitter 116.

The polarization beam splitter 72, color separation elements 74 and 92, mirrors 48 and 49, condenser lens 8
0, 82, 84, 98, 100, 102 and liquid crystal light valves 86, 88, 90, 104, 106, 108.
Are arranged so that the following conditions are satisfied. That is, the two types of polarized lights 15p and 15s separated by the polarization beam splitter 72 are separated into the color separation elements 74 and 92 and the mirror-4.
9, 48, condenser lenses 80-84, 98-102
Through the liquid crystal light valves 86-90, 104-108
Are arranged so that the optical path lengths up to are equal to each other.

The liquid crystal light valves 86 to 90, 104
˜108, the color synthesizing elements 110 and 120, the polarization beam splitter 116, and the projection lens 40 are arranged so as to satisfy the following conditions. That is, the light modulated by the liquid crystal light valves 86 to 90 and 104 to 108 is combined with the color combining elements 110 and 120 and the polarization beam splitter 116.
They are arranged so that the optical path lengths to reach the projection lens 40 via the optical path are equal to each other.

Next, the operation of the above embodiment will be described. (B) The projection light 15 output from the light source 14 is polarized by the cold mirror 47 and cold filter 50.
The splitter 72 splits the polarized light 15p of the P-polarized component and the polarized light 15s of the S-polarized component whose polarization directions are orthogonal to each other.

(B) One polarized light 15p separated by the polarization beam splitter 72 is R, G, B by the color separation element 74.
Liquid crystal light valve 8 for R, G and B
The signals are modulated by 6, 88 and 90 (P-polarized light component is modulated into S-polarized light component), color-synthesized by the color synthesizing element 110 and input to one input side of the polarization beam splitter 116.

(C) The other polarized light 15s separated by the polarization beam splitter 72 is R, G, B by the color separation element 92.
Liquid crystal light valve for R, G, and B
The signals are modulated by 04, 106, and 108 (S-polarized component is modulated into P-polarized component), color-synthesized by the color synthesizing element 120, and input to the other input side of the polarization beam splitter 116.

(D) The polarization beam splitter 116 is
Polarized light modulated by the R, G, B liquid crystal light valves 86, 88, 90 (for example, polarized light that has become an S-polarized component),
R, G, B liquid crystal light valves 104, 106, 108
The polarized light modulated by (for example, the polarized light that has become a P-polarized component) is combined and output to the projection lens 40, and the projection lens 40 projects the projection light on a screen and an image is displayed on the screen. Is displayed.

(E) At this time, since the P-polarized component and the S-polarized component of the projection light 15 output from the light source 14 whose polarization directions are orthogonal to each other are used, only one polarized component is used. Further, compared with the conventional example, it is possible to increase the light utilization rate and improve the brightness.

(F) Further, the two kinds of polarized lights 15p and 15s separated by the polarization beam splitter 72 are separated into the color separation element 7.
4, 92, Mira-49, 48 and condenser lens 8
Liquid crystal light valve 86 through 0-84, 98-102
Since the optical path lengths up to 90 to 104 to 108 are equal to each other, the uneven brightness and uneven color on the screen 40 can be reduced.

(G) Liquid crystal light valves 86-9
0, 104-108 modulated light is the color synthesizing element 110,
The optical path length to the projection lens 40 via the 120 and the polarization beam splitter 116 is two types of polarized light 15
Since the p and 15 s optical systems are equal to each other, the pixel alignment on the screen becomes easy and the pixel shift prevention becomes easy.

[0027]

【The invention's effect】

(A) Since the liquid crystal projection display device according to the present invention is configured so as to be able to utilize both two types of polarization components in which the polarization directions of the light from the light source are orthogonal to each other, as described above, It is possible to increase the light utilization rate as compared with the conventional example in which only one type of polarization component is used for projection. Therefore, when one projection device (projector) is used, the brightness on the screen can be nearly double that of the conventional one, and when the brightness on the screen is the same, the configuration of the projection device can be changed. It can be simplified and downsized.
In other words, since only one projection device, which was conventionally required for two, is required, one light source, cooling device, drive circuit, projection lens, etc.
This is because it is enough.

(B) In addition, 2 was decomposed by the polarized light decomposition element.
When the respective elements are arranged so that the optical paths of the polarized lights of different types through the color separation elements to the R, G, and B liquid crystal light valves are equal to each other, the optical path length from the light source to the liquid crystal light valve Is constant, and uneven brightness and uneven color on the screen can be reduced.

(C) Further, the respective elements are arranged so that the light paths modulated by the R, G and B liquid crystal light valves reach the projection lens through the color synthesizing element and the polarized light synthesizing element to be equal to each other. In that case, since the optical path length from the liquid crystal light valve to the projection lens is the same in each of the two types of optical systems of polarized light (for example, P-polarized light and S-polarized light), pixel alignment on the screen becomes easy, Preventing pixel shift becomes easy.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a liquid crystal projection display device according to the present invention.

FIG. 2 is a schematic configuration diagram showing a conventional example.

FIG. 3 is an explanatory diagram illustrating the operation of a liquid crystal light valve.

FIG. 4 is a configuration diagram showing a conventional example for increasing display brightness.

5 is a schematic configuration diagram of an apparatus already proposed by the present applicant to solve the problems of FIGS. 2 and 4. FIG.

[Explanation of symbols]

14 ... Light source, 15 ... Projected light, 15p ... P-polarized component of projected light 15, 15s ... S-polarized component of projected light 15, 40
... Projection lens, 72 ... Polarized light decomposing element (polarizing beam splitter), 74, 92 ... Color separating element, 86, 104
... liquid crystal light valve for R, 88, 106 ... liquid crystal light valve for G, 90, 108 ... liquid crystal light valve for B, 110, 120 ... color combining element, 116 ... polarized light combining element (polarizing beam splitter) ..

Claims (2)

[Claims] 1. A light source, a polarized light decomposing element for decomposing light from the light source into two types of polarized light having polarization directions orthogonal to each other, and two types of polarized light decomposed by the polarized light decomposing element. A color separation element that decomposes into three primary color lights of R, G, and B, and a liquid crystal light for R, G, and B that modulates the light intensity of each of the three primary color lights of R, G, and B separated by this color separation element. A valve, a color synthesizing element for synthesizing the R, G, B three primary color lights modulated by these R, G, B liquid crystal light valves for each polarization component, and two types of polarization synthesizing by these color synthesizing elements A liquid crystal projection display device comprising: a polarized light combining element for combining light; and a projection lens for projecting the light combined by the polarized light combining element onto a screen. 2. The two types of polarized light separated by the polarized light decomposition element have equal optical path lengths to reach the R, G, B liquid crystal light valves through the color separation element, and the R, G, B are the same.
For the polarized light decomposing element, the color separating element, R, G, B so that the light paths modulated by the liquid crystal light valve for light reach the projection lens through the color combining element and the polarized light combining element are equal to each other. A liquid crystal light valve, a color synthesizing element, a polarized light synthesizing element, and a projection lens are arranged.
The liquid crystal projection display device described.