JP2000131664A - Liquid crystal projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify an optical system, to miniaturize a device and to reduce a parts cost. SOLUTION: A polarizing beam splitter 5 is arranged on an incident optical path between a light source 2 and a reflection type liquid crystal panel 8 and on a reflection optical path between the reflection type liquid crystal panel 8 and a projection lens 9, and at least three pieces of the reflection type liquid crystal panels 8 are provided, and color filters 7 of at least red, blue and green are provided in front of respective reflection type liquid crystal panels 8, and a spectroscopic converging element 6 deciding the optical paths toward respective reflection type liquid crystal panels 8 is provided between the reflection type liquid crystal panels 8 and the polarizing beam splitter 5. Thus, since the need providing the polarizing beam splitters 5 by the number of pieces of the reflection type liquid crystal panels 8 is eliminated, optical parts constitution is simplified, and the device is miniaturized, and the parts cost is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projector using a reflection type liquid crystal panel.

[0002]

2. Description of the Related Art Heretofore, it has been general to use an overhead projector (OHP) for a presentation. On the other hand, in recent years, with the rapid spread of personal computers (hereinafter, abbreviated as personal computers), liquid crystal projectors are becoming popular as tools that can provide more demanding presentations. The liquid crystal projector has, for example, a liquid crystal panel for displaying an output image of a personal computer, and has a structure in which transmitted light or reflected light of the liquid crystal panel is enlarged and projected by a projection lens.

Here, most of the liquid crystal projectors currently introduced on the market use transmission type liquid crystal panels using TFTs. This transmissive liquid crystal panel includes a transistor section for driving a pixel as a liquid crystal element and a transmissive window for transmitting light. However, due to the arrangement of the transistor portion, the transmission window cannot be made very small, which causes a problem that it is difficult to increase the definition or that the efficiency is difficult to improve due to a low aperture ratio of the transmission window. I have. In addition, since the size of the transmission window and the size of the transistor portion are in a trade-off relationship, there is a problem that the transistor portion cannot be made too large.

On the other hand, in a reflection type liquid crystal panel, since the transistor portion is disposed below the reflection surface, the transistor portion can be about twice as large as the transmission type liquid crystal panel. In addition, there is no structural restriction for higher definition as in the transmission window of the transmission type liquid crystal panel. Therefore, the reflection type liquid crystal panel is expected to be applied to a liquid crystal projector because it has excellent characteristics that high definition can be easily achieved and light is not reduced in the reflection type liquid crystal panel. .

FIG. 9 is a schematic diagram showing characteristics of a reflection type liquid crystal element. First, the reflective liquid crystal element 101 is
A mirror surface 103, a liquid crystal 104, a transparent electrode 105, and a cover glass 106 are laminated on the upper surface. When the liquid crystal 104 is off, the light enters and the mirror surface 10
9 is emitted as s-polarized light (FIG. 9).
(See (a)). On the other hand, when the liquid crystal 104 is on,
The s-polarized light that has entered and reflected the mirror surface 103 is emitted as p-polarized light (see FIG. 9B).

FIGS. 10 and 11 show a reflection type liquid crystal element 10.
FIG. 2 is a schematic diagram showing the principle when 1 is applied to a liquid crystal projector. In order to use the reflection type liquid crystal element 101 in a liquid crystal projector, a polarizing beam splitter 109 is provided between a reflection type liquid crystal panel 107 having a large number of reflection type liquid crystal elements 101 and a light source 108. Only the polarized light is reflected by the polarizing beam splitter 109 and guided to the reflective liquid crystal panel 107. Then, the reflective liquid crystal panel 1
When the reflective liquid crystal element 101 of FIG.
As shown in (5), since the reflected light of the reflection type liquid crystal element 101 remains s-polarized light, it is reflected by the polarization beam splitter 109 and returns. On the other hand, when the reflection type liquid crystal element 101 of the reflection type liquid crystal panel 107 is on, as shown in FIG. 11, the reflected light of the reflection type liquid crystal element 101 becomes p-polarized light and thus transmits through the polarization beam splitter 109. And projection lens 1
10 is incident. Thereby, the reflection type liquid crystal panel 10
The display image 7 is enlarged and projected at a predetermined position by the projection lens 110.

FIG. 12 is a schematic diagram of an optical system showing a conventional example of a color liquid crystal projector using the reflection type liquid crystal panel 107. In the example shown in FIG. 12, three reflective liquid crystal panels 107, red, green, and blue color filters 111, three polarization beam splitters 109, and two dichroic mirrors 112 are provided for colorization.
And one dichroic prism 113 is used. That is, the light from the light source 108 is
, The two dichroic mirrors 112 and one total reflection mirror 1 having different wavelength characteristics.
15 is used to split the wavelength of light from the light source 108 into three color wavelengths of red, green and blue. As for the light of each wavelength, only the s-polarized light is incident on the reflective liquid crystal panel 107 by the three polarizing beam splitters 109,
reflect. At this time, each s-polarized light passes through the color filter 111 of the corresponding color. Then, the reflection type liquid crystal panel 1
The reflected light 07 is condensed on the dichroic prism 113. In the dichroic prism 113, only the p-polarized light of the reflected light from the reflective liquid crystal panel 107 is combined to form a projection image, which is incident on the projection lens 110. Thus, the synthesized color projection image is enlarged and projected at a predetermined position.

[0008]

However, in a conventional liquid crystal projector using a reflection type liquid crystal panel, at least three polarizing beam splitters 109, a dichroic mirror 112, and a dichroic mirror 112 are provided in the optical system as illustrated in FIG. It requires a prism 113 and its optical path is also complicated. For this reason, there is a problem that the structure is complicated and the size of the apparatus is increased, and the cost of parts is high.

An object of the present invention is to provide a liquid crystal projector using a reflection type liquid crystal panel which can simplify an optical system.

Another object of the present invention is to provide a liquid crystal projector using a reflection type liquid crystal panel which can reduce the size of the device.

Another object of the present invention is to provide a liquid crystal projector using a reflection type liquid crystal panel which can reduce the cost of parts.

[0012]

According to a first aspect of the present invention, there is provided a liquid crystal projector including a light source and a projection lens, and a reflective liquid crystal panel on an optical path of the liquid crystal projector. One polarization beam splitter is arranged on the incident light path between the reflection type liquid crystal panel and the projection lens and on the reflection light path between the reflection type liquid crystal panel and the projection lens. Was standardized.

Therefore, the s-polarized light of the light from the light source is reflected by the polarization beam splitter, enters the reflection type liquid crystal panel, and is reflected by the reflection type liquid crystal panel. At this time, when each liquid crystal element of the reflective liquid crystal panel is off, s-polarized light is reflected, and when each liquid crystal element is on, p-polarized light is reflected. Therefore, only when the reflective liquid crystal panel is on, the p-polarized light, which is the reflected light, passes through the polarizing beam splitter and enters the projection lens. As a result, the projection lens projects an image corresponding to the display on the reflective liquid crystal panel at a predetermined position.

According to a second aspect of the present invention, there is provided a liquid crystal projector, comprising: a light source; a polarizing beam splitter that reflects only s-polarized light or only p-polarized light of the light from the light source; and an s-polarized light or a p-polarized light that reflects the polarized beam splitter. A reflective liquid crystal panel disposed on an optical path and reflecting incident light in a direction of a reflection angle of 0 degree; and a p-polarized or s-polarized light reflected on the reflective liquid crystal panel and transmitted through a polarizing beam splitter. a projection lens for projecting a projection image using p-polarized light or s-polarized light at a predetermined position.

Therefore, the s-polarized light of the light from the light source is reflected by the polarizing beam splitter, enters the reflective liquid crystal panel, and is reflected by the reflective liquid crystal panel. At this time, when each liquid crystal element of the reflective liquid crystal panel is off, s-polarized light is reflected, and when each liquid crystal element is on, p-polarized light is reflected. Therefore, only when the reflective liquid crystal panel is on, the p-polarized light, which is the reflected light, passes through the polarizing beam splitter and enters the projection lens. As a result, the projection lens projects an image corresponding to the display on the reflective liquid crystal panel at a predetermined position.

According to a third aspect of the present invention, in the liquid crystal projector according to the first or second aspect, at least three reflective liquid crystal panels are provided, and at least red, blue and green colors are provided on the front surface of each reflective liquid crystal panel. A filter is provided, and between the reflection type liquid crystal panel and the polarizing beam splitter, a spectral condensing element for defining an optical path toward each reflection type liquid crystal panel is provided.

Therefore, the s-polarized light reflected by the polarization beam splitter is split by the spectral condensing element and is incident on each reflection type liquid crystal panel. Then, the light reflected from each reflective liquid crystal display panel is transmitted through a color filter of each color, and is collected again by a spectral light condensing element, and a color image including three primary colors is synthesized, and this color image is converted by a polarizing beam splitter. Only the p-polarized light is transmitted and projected at a predetermined position by the projection lens. In this case, since the spectral condensing elements are arranged between the reflection type liquid crystal panel and the polarization beam splitter, it is not necessary to provide polarization beam splitters by the number of the reflection type liquid crystal panels. It is possible to handle light before and after light collection by the light collection element.

Here, the spectral condensing element is a fourth aspect of the present invention.
A dichroic prism can be used as in the invention described, or a dichroic mirror can be used as in the invention described in claim 5. In the former case, the size of the optical system can be reduced, and in the latter case, the component cost of the optical system can be reduced.

The invention according to claim 6 is the invention according to claims 1 to 5
The liquid crystal projector according to any one of the above, further comprising light collecting means for collecting light on each liquid crystal element of the reflective liquid crystal panel.

Therefore, the light collection efficiency of each liquid crystal element of the reflection type liquid crystal panel is improved, and the efficiency of using the reflected light is improved.

Here, as the light condensing means, a microlens array arranged on the front surface of the reflection type liquid crystal panel is used as in the invention according to claim 7, or the reflection is performed as in the invention according to claim 8. It is possible to use a pair of lenticular lenses arranged on the front surface of the liquid crystal panel and arranged orthogonally to each other.

The ninth aspect of the present invention relates to the first to eighth aspects.
The liquid crystal projector according to any one of the above, further comprising a polarization conversion element between the light source and the polarization beam splitter.

Therefore, the p-polarized light of the light from the light source is converted into the s-polarized light by the polarization conversion element, thereby improving the use efficiency of the light from the light source.

[0024]

FIG. 1 shows a first embodiment of the present invention.
A description will be given with reference to FIG. 1 is a schematic diagram of an optical system, FIG. 2 is a side view of a liquid crystal display panel and a microlens array, FIG. 3 is a perspective view thereof, and FIG. 4 is a block diagram of a drive control circuit of a reflective liquid crystal panel.

As shown in FIG. 1, the optical system of the liquid crystal projector 1 according to the present embodiment, whose appearance is not shown, includes a light source 2, a cold mirror 3, a polarization conversion element 4, a polarization beam splitter 5, and a spectral condensing element 6. , Three color filters 7, three reflective liquid crystal panels 8, and a projection lens 9.

The light source 2 is a halogen lamp, and has a reflector 10 for improving light use efficiency. A color temperature sensor 11 is provided near the light source 2. However, the light source 2 is not limited to a halogen lamp, and various lamps such as a xenon lamp can be used.

The cold mirror 3 is a mirror having a property of transmitting light having a wavelength equal to or greater than the infrared region, for example, 750 nm, and reflecting only light having a short wavelength equal to or smaller than the infrared light. In the liquid crystal projector 1 of the present embodiment, light that does not reach the infrared region reflected by the cold mirror 3 is used.

The polarization conversion element 4 comprises a first lens array 12a, a second lens array 12b, a condenser lens 13 and a polarization conversion unit 14 which are arranged apart from each other. The second lens array 12b and the condenser lens 13 And have a structure in which the polarization conversion unit 14 is sandwiched. The polarization conversion unit 14 is configured by a combination of a plurality of polarization splitter films 15 and a λ / 2 wave plate 16 that are inclined and reflect s-polarized light, and emits s-polarized light reflected by the polarization splitter film 15. In addition, the optical element has a structure in which p-polarized light transmitted through the polarization splitter film 15 is converted into s-polarized light by the λ / 2 wavelength plate 16 and emitted. Therefore, the light including the s-polarized light and the p-polarized light incident on the polarization conversion element 4 is converted from the s-polarized light into the s-polarized light and emitted. That is, the polarization conversion element 4 converts p-polarized light discarded by the optical system at the subsequent stage into s-polarized light.
It is possible to prevent a decrease in light use efficiency.

The polarization beam splitter 5 reflects the cold mirror 3 radiated from the light source 2 and reflects the s-polarized light transmitted through the polarization conversion element 4 at a reflection angle of 90 degrees. The light reflection direction in this case is a direction in which the reflected light is incident on the spectral condensing element 6.

In this embodiment, a dichroic prism 17 is used as the spectral condensing element 6. The dichroic prism 17 includes a pair of prisms including a red layer 18r having a property of reflecting only light having a long wavelength of red or more and a blue layer 18b having a property of reflecting light having a short wavelength of blue or less. 18 are arranged at vertically symmetric positions, and a pair of ordinary prisms 19 are arranged at left and right symmetric positions.
Is an optical element formed by bonding. Therefore,
When viewed as one spectral condensing element 6, the dichroic prism 17 has a red layer 18r parallel to the polarization beam splitter 5 and a blue layer 18b crossing the red layer 18r at right angles. The red layer 18r has a property of reflecting only light having a longer wavelength than the wavelength of red light, and the blue layer 18b has a property of reflecting only light having a shorter wavelength equal to or less than the wavelength of blue light. The red layer 18
The r layer and the blue layer 18b are both non-metal multilayer films.

The color filters 7 include a red filter 7r, a green filter 7g, and a blue filter 7b.
Filters corresponding to the three colors of light are prepared. These three color filters 7 and three reflective liquid crystal panels 8 are arranged corresponding to the red layer 18 r and the blue layer 18 b of the dichroic prism 17. That is, the red layer 1 of the dichroic prism 17
A red panel 8r, which is one reflective liquid crystal panel 8, is disposed via a red filter 7r in the direction of reflection of light of a longer wavelength than red that reflects 8r. Further, a blue panel 8b, which is another reflective liquid crystal panel 8, is disposed via a blue filter 7b in the direction of reflection of short-wavelength light of blue or less that reflects the blue layer 18b of the dichroic prism 17. Further, the red panel 18r and the blue layer 18b of the dichroic prism 17 pass through the green filter 7g in the direction of transmission of light having a wavelength shorter than red, which is shorter than red, and which is not reflected. 8 g are arranged. The three reflective liquid crystal panels 8 (8r, 8
g, 8b) themselves are all the same.

As shown in FIGS. 2 and 3, the reflective liquid crystal panel 8 has a microlens array 20 as a light condensing means on the front surface thereof. That is, the reflective liquid crystal panel 8
A mirror surface 22, a liquid crystal 23, and a coating glass 24 are provided on a substrate 21.
Are laminated. The liquid crystal 23 includes a partition 25
The liquid crystal 23 divided in a matrix by the partition walls 25 constitutes one liquid crystal element 26, that is, one liquid crystal pixel. Then, as shown in FIGS. 2 and 3, the microlens array 20 also includes a plurality of condenser lenses 2.
7 are arranged in a matrix, and each condenser lens 27 corresponds to each liquid crystal element 26. here,
The condenser lens 27 condenses the light on the liquid crystal 23 and improves the light use efficiency. The operation principle of the reflection type liquid crystal panel 8 is as described in the section of the prior art with reference to FIGS. 9 to 11, and the description is omitted.

Here, a drive control circuit of each liquid crystal element 26 of the reflection type liquid crystal panel 8 will be described with reference to FIG. First,
The drive control circuit includes, for example, an image signal transmitted from a personal computer or the like and an N signal transmitted from a television or a VTR or the like.
And a TSC video signal.

An image signal sent from a personal computer or the like is
Red, green and blue input signals (RGB
Signal) and a horizontal / vertical synchronization signal. An RGB signal included in such an image signal is converted to an adjustment correction circuit 28 having functions of a gain adjustment circuit, a brightness adjustment circuit, and a γ correction circuit.
Is sampled by the sampling circuit 29 and field-inverted by the field inversion circuit 30,
The signals are input to the red panel 8r, the green panel 8g, and the blue panel 8b, which are the respective reflective liquid crystal panels 8, by the drive amplifier 31. Further, the drive control circuit makes a signal determination in the input signal detector 34 based on the horizontal synchronization signal and the vertical synchronization signal included in the image signal,
The clock is reproduced by the LL circuit 35. The timing generator 36 that receives the input signals of the input signal detector 34 and the output signal of the PLL circuit 35 and generates various timing signals includes a reflection type liquid crystal panel 8 (8r, 8g, 8b), a sampling circuit 29, and a field inversion circuit. The timing signal is output to 30.

On the other hand, the NTSC video signal is input to the above-described adjustment and correction circuit 28 via the NTSC decoder 32, and is subjected to signal processing in the same manner as the RGB signals. Such an image signal and an NTSC video signal are connected to a switching circuit 3
According to the switching operation of No. 3, it is selectively taken into the drive control circuit.

It should be noted that each of the reflection type liquid crystal panels 8
The distances to (8r, 8g, 8b) are all the same.
Further, the distances from the reflective liquid crystal panels 8 (8r, 8g, 8b) to the projection lens 9 are all the same.

In such a configuration, of the light emitted from the light source 2, light having a wavelength shorter than that of the infrared region is reflected by the cold mirror 3, and after being completely converted into s-polarized light by the polarization conversion element 4, the polarization beam splitter 5 is reflected. The red, green, and blue light is split by the dichroic prism 17 and the light of each color is reflected by the red liquid crystal panel 8 as a red panel 8r and a green panel 8g.
And into the blue panel 8b. That is, the red layer 18r of the dichroic prism 17 reflects red light and guides it to the red panel 8r, and the blue layer 18b of the dichroic panel 17 reflects blue light and guides it to the blue panel 8b. The blue layer 18b transmits green light and transmits the green panel 8
g. Here, each reflective liquid crystal panel 8 is turned on / off in response to an image signal input to the liquid crystal projector 1, reflects s-polarized light as s-polarized light when off, and reflects s-polarized light as p-polarized when on. I do. And these s
The reflected light composed of the polarized light or the p-polarized light is condensed and synthesized by the dichroic prism 17 and returns to the polarization beam splitter 5. At this time, each reflective liquid crystal panel 8
Since only the p-polarized light when the liquid crystal element 26 is turned on is transmitted through the polarization beam splitter 5, the transmitted light is enlarged and projected on the screen 37 by the projection lens 9. As a result, an image corresponding to the image signal input to the liquid crystal projector 1 is displayed on the screen 37.

Here, in the liquid crystal projector 1 of the present embodiment, the reflection type liquid crystal panel 8 and the polarization beam splitter 5
Since the dichroic prism 17 as the spectral condensing element 6 that defines an optical path toward each reflective liquid crystal panel 8 is disposed between the reflective liquid crystal panels 8, it is not necessary to provide the polarization beam splitters 5 by the number of the reflective liquid crystal panels 8. One polarization beam splitter 5 can handle the light before and after the light is condensed by the light condensing element 6. Accordingly, the configuration of the optical components is simplified, the size of the device is reduced, and the component cost is reduced.
In this case, the use of the dichroic prism 17 as the spectral condensing element 6 also contributes to further miniaturization of the device. Moreover, in the liquid crystal projector 1 of the present embodiment, all the light from the light source 2 is converted into s-polarized light by the polarization conversion element 4, and the light is condensed on each liquid crystal element 26 of the reflective liquid crystal panel 8 by the microlens array 20. Therefore, the light use efficiency is excellent.

FIG. 5 is a perspective view of a lenticular lens array 41 as a condensing means that can be used in place of the microlens array 20 as a modification. In the lenticular lens array 41, a pair of lenticular lenses 41a and 41b are provided on the front and back sides in a direction orthogonal to each other. Such a lenticular lens array 41 includes a pair of lenticular lenses 41a and 41a.
A plurality of condensing lenses 27 are formed in a matrix by the combination of b, thereby providing the same operation and effect as the microlens array 20.

A second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a schematic diagram of the optical system. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In this embodiment, a dichroic mirror 51 is used as the spectral condensing element 6 instead of the dichroic prism 17. That is, the position where the reflected light of the polarization beam splitter 5 is guided is located at the red layer 52.
A first dichroic mirror 52 provided with an r and a second dichroic mirror 53 provided with a blue layer 53b are arranged in order. Then, the total reflection mirror 54 is reflected in the direction of reflection of light having a longer wavelength than red reflecting the red layer 52r.
The red panel 8r is arranged together with the red filter 7r, the blue panel 8b is arranged together with the blue filter 7b in the direction of reflection of short-wavelength light below blue that reflects the blue layer 53b, and the red layer 52r and the blue layer 53.
A green panel 8g is arranged together with the green filter 7g in the transmission direction of b.

It should be noted that each of the reflection type liquid crystal panels 8
The distances to (8r, 8g, 8b) are all the same.
Further, the distances from the reflective liquid crystal panels 8 (8r, 8g, 8b) to the projection lens 9 are all the same.

In such a configuration, of the light emitted from the light source 2, the light having a shorter wavelength than the infrared region is reflected by the cold mirror 3, and after being converted into s-polarized light by the polarization conversion element 4, the polarization beam splitter 5 is reflected. Then, the light is split into red, green, and blue light by the dichroic mirror 51, and the light of each color is incident on the red panel 8r, the green panel 8g, and the blue panel 8b, which are the reflective liquid crystal panels 8. That is, the red layer 52r provided in the first dichroic mirror 52 reflects the red light and guides it to the red panel 8r, and the blue layer 53b provided in the second dichroic mirror 53 reflects the blue light and forms the blue panel 8b. Guide, red layer 52r
The blue layer 53b transmits green light and guides it to the green panel 8g. Here, each reflective liquid crystal panel 8
It is turned on / off in accordance with an image signal input to the liquid crystal projector 1, and when off, reflects s-polarized light as s-polarized light, and when on, reflects s-polarized light as p-polarized light. The reflected light composed of the s-polarized light or the p-polarized light is condensed and synthesized by the dichroic mirror 51 and returns to the polarization beam splitter 5. At this time, only the p-polarized light when the liquid crystal element 26 of each reflective liquid crystal panel 8 is on is transmitted through the polarization beam splitter 5, and the transmitted light is enlarged and projected on the screen 37 by the projection lens 9. As a result, an image corresponding to the image signal input to the liquid crystal projector 1 is displayed on the screen 37.

In the liquid crystal projector 1 of the present embodiment,
Since the dichroic mirror 51 is used as the spectral condensing element 6, the component cost can be further reduced.

FIG. 7 shows a first modification of the second embodiment of the present invention. In this modification, as a configuration of the dichroic mirror 51, a second dichroic mirror 61 having a green layer 61g is used instead of the second dichroic mirror 53 having a blue layer 53b. The green layer 61g has a characteristic of reflecting only light having a longer wavelength than the green wavelength. The green panel 8g is arranged together with the green filter 7g in the direction of reflection of light having a wavelength equal to or greater than green that reflects the green layer 61g, and together with the blue filter 7b in the direction of transmission of light having a wavelength shorter than the green transmitted through the green layer 61g. A blue panel 8b is arranged.

Accordingly, the red layer 52r provided in the first dichroic mirror 52 reflects the red light and guides it to the red panel 8r, and the second dichroic mirror 6
The green layer 61g included in 1 reflects green light and guides it to the green panel 8g, and the red layer 52r and the green layer 61b transmit blue light and guides it to the blue panel 8b.

FIG. 8 shows a second modification of the second embodiment of the present invention. In this modification, as the configuration of the dichroic mirror 51, a first dichroic mirror 71 having a blue layer 71b and a second dichroic mirror 72 having a green layer 72g are arranged in the light reflection direction of the polarization beam splitter 5. They were arranged in order. Blue layer 71b
Has a characteristic of reflecting only light having a wavelength shorter than the short wavelength of blue. The green layer 72g has a property of reflecting only light having a short wavelength equal to or less than the wavelength of green. Then, the blue panel 8b is arranged together with the blue filter 7b via the total reflection mirror 54 in the direction of reflection of light having a short wavelength of blue or less that reflects the blue layer 71b.
A green panel 8g is arranged together with a green filter 7g in the direction of reflection of light having a wavelength equal to or less than green that reflects 2g, and a red filter is disposed in the direction of transmission of light having a longer wavelength than blue and green that transmits through the blue layer 71b and the green layer 72g. A red panel 8r is arranged together with 7r.

Therefore, the blue layer 71b of the first dichroic mirror 71 reflects the blue light and guides the blue light to the blue panel 8b.
The green layer 72g provided in 2 reflects green light and guides it to the green panel 8g, and the blue layer 71b and the green layer 72b transmit red light and guides it to the red panel 8r.

In each of the above embodiments, p-polarized light and s
The term polarization does not alter the essence of the invention, even if all are used interchangeably.

In each of the above embodiments, an example using the reflection type liquid crystal panel 8 has been described. However, it goes without saying that a configuration in which a transmission type liquid crystal panel is used and a mirror is disposed behind the same is also used. The function of the function is achieved.

The dichroic prism 17 may have a prism configuration generally used in a three-plate color video camera.

Further, the micro lens array 20 and the lenticular lens array 41 are effective especially when a transmission type liquid crystal panel is used, but they are not essential components of the present invention.

[0053]

According to the invention of the liquid crystal projector according to the first or second aspect of the present invention, the liquid crystal projector is provided on the incident optical path between the light source and the reflective liquid crystal panel and on the reflected optical path between the reflective liquid crystal panel and the projection lens. Since one polarizing beam splitter was placed,
The optical component configuration can be simplified.

According to a third aspect of the present invention, in the liquid crystal projector according to the first or second aspect, at least three reflective liquid crystal panels are provided, and at least red, blue, and green color filters are provided in front of each reflective liquid crystal panel. Since there is provided a spectral condensing element that defines an optical path toward each reflection type liquid crystal panel between the reflection type liquid crystal panel and the polarization beam splitter, there is no need to provide polarization beam splitters by the number of reflection type liquid crystal panels, A single polarization beam splitter can handle the light before and after the light is condensed by the spectral light condensing element. Therefore, the configuration of the optical components can be simplified, the device can be reduced in size, and the cost of the components can be reduced.

According to a fourth aspect of the present invention, in the liquid crystal projector according to the third aspect, since a dichroic prism is used as the spectral condensing element, the size of the optical system can be further reduced.

According to a fifth aspect of the present invention, in the liquid crystal projector according to the third aspect, a dichroic mirror is used as the spectral condensing element, so that the cost of parts of the optical system can be further reduced.

The invention described in claim 6 is the invention according to claims 1 to 5
In the liquid crystal projector according to any one of the above, a light condensing means for condensing light on each liquid crystal element of the reflection type liquid crystal panel, for example, a microlens array (claim 7) or a pair of lenticular lenses arranged in a direction orthogonal to each other. (Claim 8)
Because of this, the light collection efficiency of each liquid crystal element of the reflective liquid crystal panel can be improved, and the efficiency of using the reflected light can be improved.

The ninth aspect of the present invention provides the first to eighth aspects.
In the liquid crystal projector according to any one of the above, since a polarization conversion element is provided between the light source and the polarization beam splitter, p-polarized light of light from the light source can be converted to s-polarized light in the polarization conversion element, Thus, the efficiency of using light from the light source can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an optical system according to a first embodiment of the present invention.

FIG. 2 is a side view of a liquid crystal display panel and a microlens array.

FIG. 3 is a perspective view thereof.

FIG. 4 is a block diagram of a drive control circuit of the reflective liquid crystal panel.

FIG. 5 is a perspective view of a lenticular lens array that can be used in place of the micro lens array.

FIG. 6 is a schematic diagram of an optical system according to a second embodiment of the present invention.

FIG. 7 is a schematic diagram of an optical system showing a first modification of the second embodiment of the present invention.

FIG. 8 is a schematic diagram of an optical system showing a second modification of the second embodiment of the present invention.

FIG. 9 is a schematic diagram showing characteristics of a reflective liquid crystal element;
(A) shows a switch-off state, and (b) shows a switch-on state.

FIG. 10 is a schematic diagram showing a principle of applying a reflection type liquid crystal element to a liquid crystal projector, and shows a switch-off state.

FIG. 11 is a schematic diagram showing a principle in a case where the reflection type liquid crystal element is applied to a liquid crystal projector, and shows a switch-on state.

FIG. 12 is a schematic diagram of an optical system showing a conventional example of a color liquid crystal projector using a reflection type liquid crystal panel.

[Explanation of symbols]

 Reference Signs List 2 light source 4 polarization conversion element 5 polarization beam splitter 6 spectral condensing element 7 color filter 8 reflective liquid crystal panel 9 projection lens 17 dichroic prism 20 condensing means (microlens array) 41a, 41b condensing means (lenticular lens) 51 dichroic mirror

Claims (9)

[Claims] 1. A liquid crystal projector comprising: a light source and a projection lens; and a reflection type liquid crystal panel on an optical path thereof, wherein the reflection type liquid crystal panel is provided on an incident light path between the light source and the reflection type liquid crystal panel. One polarization beam splitter is arranged on the reflection optical path between the projection lens and the common light path and the output light path between the polarization beam splitter and the reflective liquid crystal panel. Characteristic liquid crystal projector. 2. A light source, a polarizing beam splitter that reflects only s-polarized light or only p-polarized light out of light from the light source, and an incident light that is disposed on an optical path of s-polarized light or p-polarized light that reflects the polarizing beam splitter. A reflective liquid crystal panel that reflects light in a direction of a reflection angle of 0 degree; and a p-polarized light or an s-polarized light that is disposed on an optical path of p-polarized light or s-polarized light that reflects the reflective liquid crystal panel and passes through the polarizing beam splitter. And a projection lens for projecting a projection image by a projection lens at a predetermined position. 3. The reflective liquid crystal panel is provided with at least three reflective liquid crystal panels, and at least red, blue and green color filters are provided on a front surface of each of the reflective liquid crystal panels, and the reflective liquid crystal panel and the polarizing beam splitter are provided. 3. The liquid crystal projector according to claim 1, further comprising a spectral condensing element that defines an optical path toward each of the reflective liquid crystal panels. 4. The liquid crystal projector according to claim 3, wherein said spectral condensing element is a dichroic prism. 5. The liquid crystal projector according to claim 3, wherein said spectral condensing element is a dichroic mirror. 6. The liquid crystal projector according to claim 1, further comprising a light condensing means for condensing light on each liquid crystal element of the reflection type liquid crystal panel. 7. The liquid crystal projector according to claim 6, wherein said light condensing means is a microlens array arranged on a front surface of said reflection type liquid crystal panel. 8. The liquid crystal projector according to claim 6, wherein said condensing means is a pair of lenticular lenses arranged on the front surface of said reflection type liquid crystal panel and arranged in a direction perpendicular to each other. 9. The liquid crystal projector according to claim 1, further comprising a polarization conversion element between said light source and said polarization beam splitter.