JPH05100331A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To enhance liquid utilization efficiency by providing polarization panels so as to correspond to the respective split polarized beams. CONSTITUTION:The light emitted from the illuminating light source of a liq. crystal projector 21 is reflected by a reflector 23, made incident on a polarized beam splitter 24 and split by the bonded surface of two prisms into linearly polarized beam in two directions. The polarized beams split by the splitter 24 are injected into the reflecting mirrors 25 and 35 with their optical axes at an angle of 90 deg. to each other, reflected into the polarized beams a2 and a3, made incident on liq. crystal panels 26 and 36 and optically rotated when a voltage is not impressed into the beams a2 and a3' to be emitted. The beams a2 and a3 split by a first polarized beam splitter 28 are again synthesized by a second polarized beam splitter 28 set at the intersections of the respective optical axes, and the synthesized light is magnified by a projection lens 29 and projected on a projection screen 30.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In recent years, image display devices, particularly television monitors, tend to have a large screen, and various display devices have been developed to realize this large screen. Among them, a projection device using a liquid crystal light valve is relatively often used because it is highly likely to be small and lightweight and that a large screen display can be easily enjoyed even in a general home.

For example, a liquid crystal panel used in a liquid crystal projector or a liquid crystal television needs to transmit only a polarized component in a specific direction out of natural light containing polarized components in all directions, and therefore a polarized light is polarized by a polarizer. Is going.
In general, polarized light includes S-polarized light and P-polarized light having a 90-degree polarization angle different from this S-polarized light. As shown in FIG. 6, the front surface side and the rear surface side of the liquid crystal panel 1 respectively have a first polarization. Polarizer 2
The first and second polarizers 22 are arranged so that their polarization axes are orthogonal to each other. Liquid crystal panel 1 arranged in this way
First, the light beam emitted from the illumination light source 3 enters the first polarizer 21 arranged on the front side of the liquid crystal panel 1, and only the light beam in the direction A in the figure is transmitted to allow liquid crystal to pass through. It is designed to enter 4. When no voltage is applied to the liquid crystal 4, since the liquid crystal molecules are arranged in a state of being twisted by 90 degrees, the incident light on the liquid crystal 4 rotates the plane of polarization by 90 degrees along the molecular axis of the liquid crystal molecule. Since the liquid crystal 4 propagates after being propagated, the polarization direction is 9 when exiting the liquid crystal 4.
It is rotated 0 degrees and is in the direction B in the figure. However, since the polarization axes of the first polarizer 21 and the second polarizer 22 are orthogonal to each other, the light passing through the liquid crystal 4 can pass through the second polarizer 22. If not, the display surface becomes bright.

On the other hand, when a voltage is applied to the liquid crystal 4, the alignment of the liquid crystal molecules changes, and the optical activity of the liquid crystal 4 is lost, so that the incident light on the liquid crystal 4 has its polarization direction rotated. Without passing through the liquid crystal 4, it cannot pass through the second polarizer 22. For this reason,
Since there is no light emitted from the second polarizer 22, the display surface (not shown) is in a dark state.

As described above, when the light emitted from the illumination light source 3 is emitted from the second polarizer 22 of the liquid crystal panel 1, it is P-polarized by the arranged liquid crystal panel 1.
Alternatively, only one of S-polarized light can be emitted. That is, the output is reduced by about 50% as compared with the output light component of the illumination light source 3, and the reduced output of about 50% is almost absorbed by the first polarizer 21. Will be done.

As shown in FIG. 7, for example, in the liquid crystal projector device 5, the light emitted from the light source 6 is reflected by the reflector 7, and the reflected light is transmitted to the liquid crystal panel 8 to be converted into polarized light and a video signal. The image is enlarged by the projection lens 9 and projected on the projection screen 10. The liquid crystal panel 8 has the same structure as that of the liquid crystal panel 1 described above, and thus the light emitted from the light source 6 is transmitted by the first polarizer 11 only in the polarized light of a specific direction. Then, the light other than the specific polarized light is emitted from the first polarizer 11
Therefore, the light finally transmitted through the second polarizer 12 is reduced to about 50%. That is, in order to obtain an image of a predetermined brightness on the projection screen 10, the output of the light source 6 must be doubled to obtain an image of a predetermined brightness. In addition, about 50% of the illumination light from the light source 6 is absorbed by the first polarizer 11 and becomes heat, so that the temperature of the liquid crystal panel 8 rises. It is necessary to cool the polarizer having a problem with the (property).

[0007]

As described above, in the conventional liquid crystal projector device, in order to obtain an image having a predetermined brightness, it is necessary to output the light source having a brightness twice as high as the brightness of the image. Not only that, but about half of the output from the light source is used for heat generation which is not desirable for the polarizer, resulting in poor light utilization efficiency.

The present invention eliminates the above-mentioned problems, and by dramatically improving the utilization efficiency of illumination light as a light source, an image having a predetermined brightness can be obtained without increasing the output of illumination light. It is an object of the present invention to provide a liquid crystal display device that is capable of suppressing heat generation of a liquid crystal panel.

[0009]

A liquid crystal display device according to the present invention comprises a polarization splitting means for splitting light emitted from an illumination light source into a plurality of linearly polarized light, and the plurality of linearly polarized light split by the polarization splitting means. Each of the liquid crystal panels is image-modulated, and a display unit for displaying the plurality of linearly polarized lights which are image-modulated by these liquid crystal panels and emitted.

The display means synthesizes the linearly polarized light that has been image-modulated by the liquid crystal panel and is emitted, and the emitted light from the synthesizer on a projection screen by a projection lens. Projecting means for projecting or projecting the plurality of separated linearly polarized lights, which are image-modulated by the liquid crystal panel and emitted, onto the projection screen by the respective projection lenses, while the plurality of separated straight lines are projected on the screen It is provided with a synthesizing means for synthesizing polarized light.

Further, color separation means for respectively separating the plurality of linearly polarized lights separated by the polarization separation means into three primary colors, and image modulation of the plurality of linearly polarized three color lights separated by the color separation means. The respective liquid crystal panels and the plurality of linearly polarized lights that are image-modulated and emitted by these liquid crystal panels are synthesized by the color synthesizing unit that synthesizes the three-color light that is image-modulated by the liquid crystal panel and is emitted by the color synthesizing unit. In addition, there is provided a synthesizing unit for synthesizing the linearly polarized light separated into the plurality of pieces, and a projecting unit for projecting the light emitted from the synthesizing unit on a projection screen with a projection lens to display in color.

[0012]

In the present invention, the liquid crystal panel is provided so as to correspond to the respective polarized lights separated by the polarized light separating means, so that the image is modulated and the image projected on the projection screen is separated into the polarized lights. Are synthesized using a synthesizing means.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 relate to a first embodiment of the present invention.
Is an explanatory view showing the configuration of the liquid crystal projector, and FIG. 2 is an operation explanatory view of the polarization beam splitter.

As shown in FIG. 1, for example, in the liquid crystal projector 21, the light emitted from the illumination light source 22 having the same brightness as the conventional one is reflected by the reflector 23 and is incident on the polarization beam splitter 24. ..

As shown in FIG. 2, the polarization beam splitter 24 is formed by combining two triangular prisms, and the unpolarized light beam A is hardly lost at the joint surface of the two prisms. Ray A1 which is linearly polarized light
And a ray A2. That is, unpolarized light or linearly polarized light in two or more directions that has entered the joint surface of the polarization beam splitter 24 in which two prisms are combined transmits the linearly polarized light component A1 in one direction, but the linearly polarized light component A1 is transmitted. The orthogonal linearly polarized light component A2 is reflected.

The polarization beam splitter 24 shown in FIG.
Since it is arranged on the front surface of the reflector 23 in FIG. 1 as viewed from the Z direction in FIG. 2, the incident light A to the polarization beam splitter 24 is split into two directions of linearly polarized light. That is, the polarized light a2 'which is parallel to the paper surface of FIG. 1 and is reflected by the polarization beam splitter 24 and the polarization beam splitter 24 which is perpendicular to the paper surface.
The polarized light is separated into the polarized light a3 which has passed through. The polarized light a2 'and the polarized light a3 separated by the polarization beam splitter 24 are incident on and reflected by a reflection mirror 25 and a reflection mirror 35 provided so that their optical axes are changed by 90 degrees. And polarized light a3 '.

The polarized light a2 and the polarized light a3 'emitted from the reflection mirrors 25 and 35 are incident on the liquid crystal panel 26 and the liquid crystal panel 36 provided on the optical axis. Here, in the liquid crystal panel 26 and the liquid crystal panel 36, for example, when no voltage is applied, the incident linearly polarized light is rotated by 90 ° and emitted. That is, ray a2 and ray a3
′ Is a liquid crystal panel 26 and a liquid crystal panel 36 in which no voltage is applied.
The light is rotated by and is emitted as a light ray a2 and a light ray a3 '.
By providing the polarization beam splitter 28 at the position where the optical axes of the two intersect, the linearly polarized light perpendicular to the paper surface is transmitted and the linearly polarized light parallel to the paper surface is reflected, so that a2 is transmitted through the polarizing beam splitter 28, a3 'is reflected to a
Therefore, a2 and a3 separated by the polarization beam splitter 28 are combined again. The light beam combined by the polarization beam splitter 28 is projected by the projection lens 2
9 is enlarged, and is enlarged by a cylindrical lens or the like located in the middle of the projection screen 30 to be projected on the projection screen 30.

That is, the light ray A emitted from the illumination light source 22
Is polarized and separated by the polarization beam splitter 24 into linearly polarized light of a2 and a3, but since the polarized light is combined again by the polarization beam splitter 28, the light component is not lost. It is possible to project on the projection screen 30 without loss. Furthermore, since there is no component that is absorbed and consumed as heat, the liquid crystal panel 26
It is possible to suppress the temperature rises of 36 and 36.

Further, the liquid crystal panel 26 and the liquid crystal panel 36.
When the voltage is applied, the optical rotatory power of the liquid crystal is lost, so that the polarization directions of the incident light and the outgoing light on the liquid crystal panel 26 and the liquid crystal panel 36 do not change. Is reflected and the polarized light a3 'is transmitted, so that it does not enter the projection lens 29.

In the liquid crystal projector device 21 thus constructed, the light emitted from the illumination light source 22 can be separated by the polarization beam splitter 24 and recombined by the polarization beam splitter 28. Since the above component is not absorbed, the illumination light source can be used efficiently. Further, since the image projected on the projection screen 30 through the projection lens 29 has improved light utilization efficiency, it is not necessary to increase the output of the light source 22 to obtain a predetermined brightness.

FIG. 3 is an explanatory view showing another embodiment of the present invention. As shown in the figure, in this embodiment, instead of the reflection mirror 35, the polarization beam splitter 28, and the projection lens 30 corresponding to the polarization beam splitter 28, a polarizer 27 and a polarizer 27 are provided on the front optical axes of the liquid crystal panels 26 and 36. 37 is provided, and the projection lenses 32 and 33 are provided in front of the respective polarizers 27 and 37 on the optical axis, so that the polarized lights separated by the polarization beam splitter are combined on the projection screen. .. Other configurations are the same as those of the embodiment of FIG. 1, and the same components as those in FIG.

In the liquid crystal projector device 21 thus constructed, the light emitted from the illumination light source 22 is polarized and separated by the polarization beam splitter 24 and transmitted through the liquid crystal panels 26 and 36 and the polarizers 27 and 37. ,
By combining the rays separated into two components on the projection screen 30 via the projection lenses 32 and 33,
The same effect as that of the embodiment of FIG. 1 can be obtained.

Since the above-described embodiment is a case of a single color, an example of a case of color will be described below.

FIG. 4 shows an embodiment in which the present invention is applied to a color. As shown in the figure, the light emitted from the light source 22 is reflected by the reflector 23 and is incident on the first polarization beam splitter 24 as in the case of the above-mentioned monochromatic light, and then is polarized in parallel with the paper surface and is parallel to the paper surface. Vertical polarized light. The respective polarized lights thus separated are again incident on the second polarization beam splitter 28 via the color separation filter, the reflection mirror, the liquid crystal panel, and the color combining filter, and the separated polarized lights are combined and emitted. , Is configured to be enlarged by the projection lens and projected on the projection screen. Here, the same components as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

Note that 41a, 42a and 41b, 42b are color separation filters, 51a, 51b, 52 are reflection mirrors, and 61a, 62a, 61b, 62b are color synthesis filters. The color separation filter 41a has a spectral characteristic of transmitting the red (R) wavelength region and reflecting the blue (B) and green (G) wavelength regions, and the color separation filter 42a transmits the blue (B) wavelength and the green ( G) It has a spectral characteristic of reflecting a wavelength. The color separation filter 41b is the color separation filter 41.
The color separation filter 42b has the same characteristics as the a, and the color separation filter 42b has the same characteristics as the color separation filter 42a. Further, the color synthesis filter 61a reflects the green (G) wavelength region and reflects the red (R) wavelength region.
The color synthesis filter 62 has a spectral characteristic of transmitting in the wavelength region.
a reflects in the blue (B) wavelength range, and red (R) and green (G)
It has a spectral characteristic of transmitting in the wavelength region.

Then, the liquid crystal panels 36R, 36G, and 36 from the first polarization beam splitter 24 are separated from each other.
B and 26R, 26G, and 26B are arranged so that the optical path lengths are equal, and the respective liquid crystal panels 36 are arranged.
The optical paths from R, 36G, 36B and 26R, 26G, 26B to the second polarization beam splitter 28 are arranged so as to have the same optical path length.

In the color liquid crystal projector 21 'constructed as described above, the light emitted from the light source 22 is reflected by the reflector 23, and the reflected light is made incident on the polarization beam splitter 24 to be parallel to the paper surface. It is separated into polarized light and polarized light perpendicular to the paper surface. The respective polarized lights separated by the polarization beam splitter 24 are color separation filters 41a, 42a, 41b, 4 having the above characteristics.
2b splits into three primary colors. The spectrally colored lights of the three primary colors are driven by a video signal corresponding to the incident color light, and a liquid crystal panel 36R for image-modulating the incident color light,
It is incident on 36G, 36B and 26R, 26G, 26B. The liquid crystal panels 36R, 36G,
Image modulated with 36B and 26R, 26G, 26B 3
The color light is generated by the color synthesizing filters 61a, 6a having the above characteristics.
Colors are combined by 2a, 61b, and 62b and are incident on the second polarization beam splitter 28 to combine the polarized lights, which are projected on the projection screen 30 via the projection lens 29. By doing so, the same effect as that of the embodiment of FIG. 1 can be obtained even in the case of color.

FIG. 5 is an explanatory view of another embodiment in the case of color. As shown in the figure, the same effect as that of the embodiment of FIG. 4 can be obtained except that the spectral characteristics and arrangement position of the color synthesis filter and the spectral characteristics and arrangement position of the color synthesis filter are different.

That is, 43a, 44a, 43b, 44
b is a color separation filter, 53, 54a and 54b are reflection mirrors, and 63a, 64a, 63b and 64b are color synthesis filters. The color separation filter 43a has a spectral characteristic of transmitting the red (R) and green (G) wavelength regions and reflecting the blue (B) wavelength region, and the color separation filter 44a reflects the blue (B) wavelength and the green ( G) It has a spectral characteristic of transmitting a wavelength. The color separation filter 43b has the same characteristics as the color separation filter 43a, and the color separation filter 44b
Has the same characteristics as the color separation filter 44a.
The color synthesis filter 63a has a spectral characteristic of reflecting the green (G) wavelength region and transmitting the blue (B) wavelength region, and the color synthesis filter 64a reflects the blue (B) and green (G) wavelength region. , And has a spectral characteristic of transmitting in the red (R) wavelength region. Then, the liquid crystal panels 36R, 36G, 36B and 26R, 26 from the first polarization beam splitter 24 respectively.
G and 26B are arranged so as to have the same optical path length, and so are arranged so that the optical path lengths from the respective liquid crystal panels 36R, 36G, 36B and 26R, 26G, 26B to the second polarization beam splitter 28 are equal. ing.

Further, although the embodiment has been described with reference to the projection type liquid crystal display device, the present invention is not limited to this, and is also effective when used for a direct view type liquid crystal display device, for example.

[0031]

As described above, according to the present invention, the illumination light source is polarized and separated, and the separated polarized light is image-modulated by using each liquid crystal panel, and after the image modulation, the separating means is separated. By synthesizing the polarized light separated by the above, the component of the light absorbed in the liquid crystal panel is reduced in the liquid crystal panel, the temperature rise of the liquid crystal panel can be suppressed, and the illumination light source is lost as a whole of the device. It can be used effectively without doing.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of a polarization beam splitter.

FIG. 3 is an overall configuration diagram showing the configuration of another embodiment of the present invention.

FIG. 4 is an overall configuration diagram showing a configuration of an embodiment when the present invention is used for color projection.

FIG. 5 is an overall configuration diagram showing a configuration of another embodiment when the present invention is used for color projection.

FIG. 6 is an operation explanatory diagram of a light beam incident on a liquid crystal panel.

FIG. 7 is a configuration diagram of a conventional liquid crystal projector.

[Explanation of symbols]

 21 ... Liquid crystal projector 22 ... Illumination light source 24 ... Polarization beam splitter 25 ... Reflection mirror 26 ... Liquid crystal panel 28 ... Polarization beam splitter 29 ... Projection lens 30 ... Projection screen 35 ... Reflection mirror 36 ... Liquid crystal panel

Claims (5)

[Claims] 1. A polarized light separating means for separating emitted light from an illumination light source into a plurality of linearly polarized light, respective liquid crystal panels for image-modulating the plurality of linearly polarized light separated by the polarized light separating means, and liquid crystals thereof. A liquid crystal display device, comprising: a display unit configured to display the plurality of linearly polarized lights that are image-modulated and emitted from a panel. 2. The display means combines a plurality of the linearly polarized lights, which are image-modulated and emitted from the respective liquid crystal panels and is separated, and a light emitted from the combiner on a projection screen. The liquid crystal display device according to claim 1, further comprising: projection means for projecting. 3. The display means projects the linearly polarized light, which is image-modulated and emitted from each of the liquid crystal panels and is separated into a plurality, on a same projection screen by a projection lens corresponding to each of the emitted lights. The liquid crystal display device according to claim 1, further comprising: 4. A polarized light separating means for separating the light emitted from the illumination light source into a plurality of linearly polarized light, and a color separating means for respectively separating the plurality of linearly polarized light separated by the polarized light separating means into three primary colors, Each of the liquid crystal panels that image-modulates the plurality of linearly polarized three-color light split by the separating means, and display means that synthesizes and displays the plurality of linearly polarized light that is image-modulated and emitted from these liquid crystal panels. The liquid crystal display device according to claim 1, wherein: 5. The display means combines a color combining means for combining the three color lights which are image-modulated by the liquid crystal panel and emitted, and the linearly polarized light combined by the color combining means and separated into a plurality of colors. 5. The liquid crystal display device according to claim 4, further comprising: a projection unit that projects and synthesizes on the same projection screen with a projection lens corresponding to the emitted light.