JP2003207739A - Projection type video display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection type video display with which desired white balance can be obtained without adjusting a light valve even when an input video source is different. <P>SOLUTION: A trihedral mirror 7 is constituted by assembling a 1st reflecting surface A, a 2nd reflecting surface B, and a 3rd reflecting surface C in a regular triangular shape and has an axis of rotation in the center of the regular triangle and is rotated by a motor at intervals of 120° to reflect illumination light by one of the reflecting mirror and guide the illumination light to a 1st dichroic mirror 8. When the input video source is changed, the trihedral mirror 7 is rotated to reflect the illumination light by the reflecting surface for a new input video source. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection-type image display device in which light from a light source is split into three primary colors to generate image lights of respective colors, which are combined and enlarged and projected.

[0002]

2. Description of the Related Art For example, a three-plate type color liquid crystal projector, a light source for irradiating white light, a dichroic mirror for separating the white light into light of three primary colors, and light of the three primary colors are respectively modulated based on video signals. It is provided with three liquid crystal display panels, a dichroic prism (or a dichroic mirror) that synthesizes modulated light from each liquid crystal display panel to generate color image light, and a projection lens that magnifies and projects the color image light. Become. Further, a dichroic filter may be provided on the light incident side of each liquid crystal display panel in order to improve color purity.

[0003]

By the way, as an application of the liquid crystal projector, a form of connecting to a personal computer and projecting a computer image (especially, an explanation image for presentation) in an enlarged manner, and watching video software or the like as a home theater are used. It can be roughly divided into usage forms. Here, the input video source is different between the former and latter usage patterns, and if the white balance (color temperature) is set for one input video source, the white balance will be changed when the input video source is switched to the other input video source. Since it will collapse, the adjustment is necessary. Here, since the wavelength characteristic of each color light of the three primary colors is determined by the dichroic mirror or the dichroic filter, the white balance adjustment according to the input image source is
This is done by changing the drive voltage to each liquid crystal display panel and adjusting the transmittance thereof. However, if adjustment is made to reduce the transmittance of the liquid crystal display panel, the black level will not fall below a certain value, so the dynamic range will decrease, and the gradation expression range will become narrower. .

In view of the above circumstances, it is an object of the present invention to provide a projection type image display apparatus capable of obtaining a desired white balance even if the input image source is different, without adjusting the light valve. To do.

[0005]

A projection type image display apparatus of the present invention inputs a light source for irradiating white light, a color separation means for separating the white light into light of three primary colors, and a light of three primary colors. A projection-type image display device including a light valve that is modulated by an image signal, a combining unit that combines the modulated lights from the light valves to generate color image light, and a projection lens that magnifies and projects the color image light. In the above, on the optical path of the illumination light before being separated by the color separation means, a plurality of reflectors having different reflection characteristics are switchably provided.
By switching the plurality of reflectors, a white balance is set for the color image light according to different input image sources.

With the above configuration, when changing the input video source, it is sufficient to switch to a reflector having a reflection characteristic corresponding to the source, and a desired white balance can be obtained without requiring adjustment of the light valve. Therefore, the dynamic range does not decrease, and the gradation expression range can be maintained.

The projection type image display device of the present invention is
A light source that emits white light, a color separation unit that separates the white light into light of three primary colors, a light valve that modulates the light of the three primary colors by an input video signal, and the modulated light from each light valve are combined. In a projection-type image display device including a synthesizing unit that generates color image light and a projection lens that magnifies and projects the color image light, on the optical path of the illumination light before being separated by the color separating unit, A plurality of transmissive bodies having mutually different transmissive characteristics are switchably provided, and by switching the plurality of transmissive bodies, a white balance is set for the color video light according to different input video sources. And

With the above configuration, when changing the input video source, it is sufficient to switch to a transmissive body having a transmissive characteristic corresponding to the source, and a desired white balance can be obtained without the need for adjusting the light valve. Therefore, the dynamic range does not decrease, and the gradation expression range can be maintained.

The switching may be automatically performed according to the input video source. According to this
The user is freed from the trouble of performing a switching operation one by one according to the type of the input video source.

[0010]

DETAILED DESCRIPTION OF THE INVENTION A liquid crystal projector according to an embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 1, the light emitting section 2 of the light source 1 is
It is composed of an ultra-high pressure mercury lamp, a metal halide lamp, a xenon lamp, etc., and its irradiation light is emitted as parallel light by the parabolic reflector 3 and guided to the integrator lens 4.

The integrator lens 4 is composed of a pair of lens groups 4a and 4b, and each lens pair guides the light emitted from the light source 1 to the entire surface of a liquid crystal light valve described later. The light that has passed through the integrator lens 4 is guided to the three-sided reflection mirror 7 through the polarization conversion device 5 and the condenser lens 6.

The polarization conversion device 5 is composed of a polarization beam splitter array. All of the light that has passed through the polarization conversion device 5 has a predetermined polarization.

As shown in FIG. 3A, the three-sided reflection mirror 7 is formed by assembling a first reflection surface A, a second reflection surface B, and a third reflection surface C into an equilateral triangle shape. It has a rotation shaft at the center and is rotated by a motor (not shown). Assuming that the first reflecting surface A is responsible for the illumination light reflection in the state shown in the figure, when the three-sided reflecting mirror 7 is rotated by 120 °, the second reflecting surface B is responsible for the illumination light reflection. When the reflection mirror 7 is rotated by 120 °, the third reflection surface C serves to reflect the illumination light. The illumination light reflected by one of the reflecting surfaces of the three-sided reflecting mirror 7 is the first
It will be guided to the dichroic mirror 8.

The first dichroic mirror 8 transmits light in the red wavelength band and reflects light in the cyan (green + blue) wavelength band. The light in the red wavelength band that has passed through the first dichroic mirror 8 is reflected by the total reflection mirror 9 and the optical path thereof is changed. The red light reflected by the total reflection mirror 9 is modulated by passing through the dichroic film 10 and the transmissive liquid crystal light valve 31 for red light. On the other hand, the light in the cyan wavelength band reflected by the first dichroic mirror 8 is reflected by the second dichroic mirror 11.
Be led to.

The second dichroic mirror 11 transmits light in the blue wavelength band and reflects light in the green wavelength band. The light in the green wavelength band reflected by the second dichroic mirror 11 is guided to the transmissive liquid crystal light valve 32 for green light through the dichroic film 12 and is modulated by being transmitted therethrough. The blue wavelength band light transmitted through the second dichroic mirror 11 passes through the relay lens 13, the total reflection mirror 14, the relay lens 15, the total reflection mirror 16, and the dichroic film 17, and is a transmissive liquid crystal light for blue light. The light is guided to the bulb 33 and transmitted therethrough to be optically modulated.

The liquid crystal light valves 31, 32, and 33 include an incident-side polarization plate, a panel section in which liquid crystal is sealed between a pair of glass substrates (on which a pixel electrode and an alignment film are formed), and an emission-side polarization plate. And a plate. Liquid crystal light valve 31,3
Modulated light that is modulated by going through 2, 33 (image light of each color)
Are combined by the dichroic prism 18 to become color image light. This color image light is emitted from the projection lens 1
It is enlarged and projected by 9 and is projected and displayed on the screen.

The liquid crystal projector shown in FIG. 2 has a three-sided light-transmitting film 20 disposed between the reflection mirror 7'and the first dichroic mirror 8 instead of having the ordinary reflection mirror 7 '. This three-sided light transmitting film 20
3B, as shown in FIG. 3B, the first transmission surface D, the second transmission surface E, and the third transmission surface F are assembled so as to form a half shape of a regular hexagon, and the center of the regular hexagon is formed. It has a rotary shaft at a position such that it is rotated by a motor (not shown). Assuming that the second transmission surface E exists on the optical path in the state shown in the figure, when the three-sided light transmission film 20 is rotated clockwise by 120 °, the third transmission surface F is located on the optical path. When the three-sided light transmission film 20 is rotated counterclockwise by 120 °, the first transmission surface D is located on the optical path. Then, the illumination light transmitted through one of the transmission surfaces of the three-sided light transmission film 20 is guided to the first dichroic mirror 8.

FIG. 4 is a graph showing the wavelength-reflectance characteristics of the three-sided reflection mirror 7, where FIG. 4 (a) shows the characteristics of the first reflection surface A and FIG. 4 (a) shows the second reflection surface. The characteristic of B is shown, and the figure (a) shows the characteristic of the 3rd reflective surface C. In this embodiment, the first reflecting surface A is selected when a video signal (RGB signal) from a personal computer is input to the liquid crystal projector, and the second reflecting surface B is, for example, a video signal (composite signal) from a video tape recorder. ) Is to be selected when input to the liquid crystal projector. In addition, the third reflecting surface C is the above-mentioned RGB.
Both signals and composite signals can be used. The wavelength-reflectance characteristics shown in this figure are examples, and the present invention is not limited to these, and if the characteristics of the optical member or the liquid crystal display panel are different, different wavelength-reflectance characteristics will be adopted. .

FIG. 5 is a graph showing the wavelength-transmittance characteristic of the three-sided light transmitting film 20, where FIG. 5A shows the characteristic of the first transmitting surface D and FIG. Surface E
And the characteristics of the third transmission surface F are shown in FIG. In this embodiment, the first transmission surface D is selected when a video signal (RGB signal) from a personal computer is input to the liquid crystal projector, and the second transmission surface E is, for example, a video signal (composite signal) from a video tape recorder. ) Is to be selected when input to the liquid crystal projector. In addition, the third transmitting surface F has the above-mentioned R
Both GB signals and composite signals can be used. The wavelength-transmittance characteristics shown in this figure are examples, and the present invention is not limited to these. Further, if the characteristics of the optical member or the liquid crystal display panel are different, different wavelength-transmittance characteristics are adopted. .

Although not shown, the liquid crystal projector of this embodiment is provided with a video signal input section and a personal computer signal input section, and one of the signals is selected by the signal switching circuit. Further, a CPU (not shown) in this liquid crystal projector instructs the motor to instruct the switching operation of the signal switching circuit and to execute the switching process in the three-sided reflecting mirror 7 or the three-sided light-transmitting film 20 in response to this switching. Drive signal (forward / reverse / stop). By the processing of the CPU,
If the input image source changes, the reflection surface switching in the three-sided reflection mirror 7 or the transmission surface switching control in the three-sided light transmission film 20 is automatically performed, and a desired white balance is automatically obtained even if the input image source is different. Will be obtained.

Specifically, when a video signal (RGB signal) from the personal computer signal input section is used for video display,
When a motor is driven to select the first reflecting surface A of the three-sided reflecting mirror 7 or the first transmitting surface D of the three-sided light transmitting film 20, and a video signal (composite signal) from the video signal input section is used for video display. The motor is driven to select the second reflecting surface B of the three-sided reflecting mirror 7 or the second transmitting surface E of the three-sided light transmitting film 20. In addition, in the usage pattern in which the input of the RGB signal and the composite signal frequently changes,
It is conceivable to select the third reflecting surface C or the third transmitting surface F that can be used in either case. Further, the switching may be performed by the button operation of the user without performing the automatic switching by the CPU.

In the embodiment described above, the motor is used as the driving means for rotating the three-sided reflection mirror 7 and the three-sided light transmission film 20, but other actuators may be used. Further, although the three-sided reflection mirror 7 and the three-sided light transmission film 20 have three surfaces having different characteristics, a reflection mirror or a light transmission film having two surfaces having different characteristics may be used, or four. A reflection mirror or a light transmission film having the above surfaces may be used. Further, although the respective color image lights are combined by the dichroic prism 18, the respective color image lights may be combined by using a dichroic mirror. Also,
Even when a reflective panel is used as the liquid crystal display panel, or in a configuration including a light valve other than the liquid crystal display panel,
Such invention can be applied.

[0024]

As described above, the projection-type image display device of the present invention can be used even if the input image source changes.
It is possible to provide a desired white balance while maintaining the gradation expression range without requiring adjustment of the light valve.

[Brief description of drawings]

FIG. 1 is a plan view showing an optical system of a liquid crystal projector according to an embodiment of the present invention.

FIG. 2 is a plan view showing another optical system of the liquid crystal projector of the embodiment of the present invention.

3 (a) is an enlarged perspective view of a three-sided reflecting mirror in the optical system of FIG. 1, and FIG. 3 (b) is an enlarged perspective view of a three-sided light transmitting film in the optical system of FIG.

4 (a), (b), and (c) are graphs showing wavelength-reflectance characteristics of each surface of a three-sided reflection mirror.

5 (a), (b) and (c) are graphs showing wavelength-transmittance characteristics of each surface of the three-sided light transmitting film.

[Explanation of symbols]

1 light source 7 Three-sided reflection mirror 18 Dichroic prism 20 Three-sided transparent film 31 LCD display panel 32 LCD display panel 33 Liquid crystal display panel

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 9/31 H04N 9/31 C 9/73 9/73 BF term (reference) 2H041 AA13 AB14 AC01 AZ01 AZ05 2H088 EA14 HA11 HA13 HA21 HA24 HA28 MA05 2H091 FA01Z FA05X FA14Z FA26X FA26Z FD24 FD26 LA20 LA30 5C060 GA01 GA02 GB06 HC11 HC21 HC25 HC26 JA14 JB06 5C066 AA03 CA05 EA14 KM05 KM13

Claims (3)

[Claims] 1. A light source for irradiating white light, a color separation means for separating the white light into light of three primary colors, a light valve for modulating the light of the three primary colors by an input video signal, and a light valve from each light valve. In a projection-type image display device including a synthesizing unit that synthesizes modulated light to generate color image light and a projection lens that magnifies and projects the color image light, illumination light before being separated by the color separating unit. A plurality of reflectors having mutually different reflection characteristics are switchably provided on the optical path of, and the white balance is set to the color image light according to different input image sources by switching the plurality of reflectors. A projection type image display device characterized by being configured. 2. A light source for irradiating white light, a color separation means for separating the white light into light of three primary colors, a light valve for modulating the light of the three primary colors by an input video signal, and a light valve from each light valve. In a projection-type image display device including a synthesizing unit that synthesizes modulated light to generate color image light and a projection lens that magnifies and projects the color image light, illumination light before being separated by the color separating unit. A plurality of transmissive bodies having mutually different transmissive characteristics are switchably provided on the optical path, and by switching the plurality of transmissive bodies, a white balance is set for the color video light according to different input video sources. A projection type image display device characterized by being configured. 3. The projection type video display according to claim 1, wherein the switching is automatically performed in accordance with an input video source. apparatus.