JP2005258163A - Projector apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector apparatus in which characteristics regarding color purity as important and characteristics regarding luminance as important are electrically and quickly switched. <P>SOLUTION: The projector apparatus is provided with: a light source 1; a wheel 2 for separating light emitted from the light source 1 into red light, green light and blue light in a time division manner; a reflective liquid crystal panel 6 for forming image light by modulating each of color light components separated by the color wheel 2; and a projecting optical system 7 for projecting the image light formed by the reflective liquid crystal panel 6. On an optical path from the light source 1 up to the reflective liquid crystal panel 6, an electronic filter 4 is arranged which can electrically switch a driven state and a non-driven state, diffract both or one of a part of the short wavelength side of incident side and a part of the long wavelength side of the incident light to the outside of the optical path in the driven state and transmit the whole incident light in the non-driven state. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a projector apparatus that forms image light by modulating light emitted from a light source by a spatial light modulator using a liquid crystal panel, a micromirror, or the like, and projects the formed image light.

  2. Description of the Related Art Conventionally, projector apparatuses using a liquid crystal panel as spatial light modulation means for modulating irradiated light based on an image signal and forming desired image light are known. As this type of projector apparatus, there is a single-plate projector apparatus having one liquid crystal panel. FIG. 8 shows a schematic structure of a single-plate projector device. In the projector apparatus shown in FIG. 8, the light emitted from the light source A is collected by the reflector B provided around the light source A and guided to the color wheel C. The color wheel C has four optical elements: a red filter that transmits only red light out of incident light, a green filter that transmits only green light, a blue filter that transmits only blue light, and a white filter that transmits incident light as it is. The filters are arranged uniformly along the circumferential direction, and rotate in the circumferential direction at a predetermined speed. Accordingly, the light incident on the color wheel C is color-separated (split) into the three primary colors R, G, and B in a time-sharing manner and is incident on the light tunnel D that constitutes the integrator optical system. The light incident on the light tunnel D is made uniform in luminance distribution while passing through the light tunnel D, reflected by the reflecting mirror E, and applied to the reflective liquid crystal panel F. The liquid crystal panel F forms image light by spatially modulating the irradiated light by turning on / off each pixel in accordance with a drive signal output from a drive circuit (not shown) based on the input image signal. . The formed image light is projected through a projection lens G onto a screen (not shown). Thus, an enlarged image substantially similar to the image formed on the liquid crystal panel F is projected on the screen.

  From the above description, it is obvious that the transmission wavelength characteristic of the optical color filter constituting the color wheel greatly affects the luminance and color purity of the image projected on the screen. In general, when an optical filter having a relatively wide transmission wavelength band is used, the luminance is improved but the color purity is lowered. On the other hand, when an optical filter having a relatively narrow transmission wavelength band is used, the color purity is improved but the luminance is lowered. As described above, there is a contradictory relationship between the improvement in luminance and the improvement in color purity, and it is necessary to select the characteristics of the optical filter depending on whether luminance or color purity is more important. It was difficult to achieve both at a high level.

  Up to now, the problems relating to color separation have been described using a single-plate projector as an example. However, the above problem is that the light emitted from the light source is separated into three primary colors of R, G, and B by a dichroic mirror, and each color light is irradiated to three liquid crystal panels prepared in advance for each color to emit image light. The same applies to a three-plate projector device to be formed and a projector device that forms image light by a spatial light modulation means other than a liquid crystal panel.

In view of the above problems, Patent Document 1 proposes a liquid crystal projector device including a switching unit that switches the spectral performance of white light emitted from a light source between a wide band and a narrow band. FIG. 9 shows a basic configuration of the liquid crystal projector device disclosed in Patent Document 1. In this liquid crystal projector device, the light beam from the light source a is collected by the integrator lens b and the lens c and split into the three primary colors by the dichroic mirrors d to i. Each color light that is split is
Each of the three liquid crystal panels j to l is irradiated with light and modulated. The light-modulated color lights (R, G, and B image lights) are combined by a dichroic prism m and projected onto a screen (not shown) via a projection lens n. Further, this liquid crystal projector device includes an optical filter p having a characteristic of cutting the end of each wavelength region of each of the three primary colors as the switching means, and for high color reproduction (for narrow band), When the optical filter p is inserted into the optical path of the light before the spectrum and is used for high brightness image display (for broadband), the optical filter p is removed from the optical path.

Further, Patent Document 1 discloses a reflection portion as shown in FIG. 10 as the switching means. The reflecting part shown in FIG. 10 is a reflecting part used at the positions of the mirrors h and i in FIG. In FIG. 10, S1 represents an S polarization component in a wavelength region of about 420 nm to 490 nm for blue light, about 525 nm to 565 nm for green light, and about 600 nm to 700 nm for red light. S2 represents an S-polarized component in a region other than S1 in the wavelength regions of about 410 nm to 505 nm for blue light, about 505 nm to 580 nm for green light, and about 580 nm to 720 nm for red light.

  In the reflecting portion shown in FIG. 10, S1 + S2 (A light ray or C light ray) is incident on the first dichroic mirror q, S1 is reflected, and S2 is transmitted as it is. For high-luminance image display, the first polarization plane rotation element (which is composed of a liquid crystal layer, hereinafter referred to as a liquid crystal layer r) is controlled so as not to rotate the polarization plane, and S2 from the first dichroic mirror q is transmitted as it is. Here, the second dichroic mirror s is set to reflect S2. Accordingly, the liquid crystal portions of the liquid crystal panels j and l are irradiated with S1 + S2 through the polarizing plate t.

  On the other hand, for high color reproduction, the liquid crystal layer r is controlled to rotate the polarization plane, and the polarization plane of S2 is rotated 45 degrees. Then, the polarization plane of S2 reflected by the second dichroic mirror s is further rotated by 45 degrees in the liquid crystal layer r to become a P polarization component. As a result, the liquid crystal part cannot be transmitted through the polarizing plate t, and only S1 with high color purity is irradiated.

Further, Patent Document 1 discloses an example in which a polarizing plate is interposed between the first dichroic mirror q and the second dichroic mirror s shown in FIG. 10 and the polarizing plate t shown in FIG. 10 is unnecessary. .
JP 2001-174774 A

  As disclosed in Patent Document 1, when the spectral performance of white light is switched between wideband and narrowband by inserting / removing an optical filter into / from the optical path, the optical filter needs to be physically moved. . Therefore, a drive mechanism for moving the optical filter, a control mechanism for controlling the drive mechanism, and the like are essential, which not only complicates the configuration but also increases the cost. Further, since it is necessary to secure a moving space for the optical filter, the entire apparatus is increased in size.

  In the single-plate projector, RGB images are formed in a time division manner. For example, in the NTSC system, since the field frequency of the image signal is 60 Hz, one frame is switched in 1/60 seconds. Therefore, the color wheel separates R, G, and B colors within one frame. On the other hand, the operation speed of the polarization plane rotating element using the polysilicon liquid crystal is several m to several tens mSec. As a result, it is practically impossible to perform high-speed processing that switches the spectral performance between a wide band and a narrow band according to the color selection timing. For example, when reproducing a mixed color such as yellow or cyan, the spectral performance is switched to a broad band to improve color density, and when reproducing a single color, the spectral performance is switched to a narrow band to improve color purity. High-speed processing such as improvement is impossible.

  Furthermore, in a single-plate projector, there is a difference between white light that has passed through the white filter of the color wheel (white light emitted from the light source) and white light that is formed by combining red light, green light, and blue light. And the difference may exceed the correctable range. Therefore, when importance is attached to color purity, the image signal is generally stopped during the period in which the white filter is used (the light that has passed through the white filter is not used). However, improving the color purity by this method means lowering the luminance.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a projector device capable of switching between a color purity-oriented characteristic and a luminance-oriented characteristic at high speed while having a simple and compact configuration. It is in.

  The projector device of the present invention that achieves the above object is separated by a light source, time-division color separation means for separating light emitted from the light source into red light, green light, and blue light in a time-division manner, and time-division color separation means. A spatial light modulator that modulates each color light to form image light, and a projection optical system that projects the image light formed by the spatial light modulator, from the light source to the spatial light modulator An operating state and a non-operating state can be electrically switched on the optical path to reach, and in the operating state, a part of the short wavelength side and / or a part of the long wavelength side of the incident light are It is characterized in that an electronic filter is provided that diffracts out of the optical path, transmits other light, and transmits the incident light as it is when not operating.

  Further, another projector device of the present invention includes a light source, two or more color separation means for separating light emitted from the light source into red light, green light, and blue light, and each color light separated by each color separation means. Two or more spatial light modulation means for modulating image light to form image light, a synthesis means for synthesizing two or more color image lights formed by the respective spatial light modulation means, and image light synthesized by the synthesis means And an electronic filter similar to the above is provided on the optical path from the light source to the spatial light modulation means.

  The electronic filter can be disposed between the time-division color separation unit and the spatial light modulation unit. It can also be arranged on the optical path of each color light separated by two or more color separation means. Furthermore, two or more types of electronic filters having different wavelength bands of light to be diffracted in the operating state can be arranged in series on the same optical path.

  When the electronic filter is activated, the short wavelength side and / or the long wavelength side end of the light incident on the spatial light modulator is cut, and the color purity is improved. On the other hand, when the electronic filter is deactivated, the light incident on the electronic filter is directly incident on the spatial light modulation means, so that the luminance is improved. Furthermore, since the electronic filter can be electrically switched between an operating state and a non-operating state, the color purity-oriented characteristics and the luminance-oriented characteristics can be obtained without causing the inconvenience of the space when inserting and removing the optical filter on the optical path. The characteristics can be switched at high speed.

(Embodiment 1)
Hereinafter, an example of an embodiment of a projector apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram illustrating a schematic configuration of the projector apparatus according to the present embodiment. The projector apparatus of this example includes a light source 1, a color wheel 2 as time-division color separation means, a light tunnel 3, an electronic filter 4, a reflecting mirror 5, and a reflective liquid crystal panel 6 as spatial light modulation means. And a projection optical system 7.

  The light source 1 is a high pressure discharge lamp such as a xenon lamp, a metal halide lamp, or a high pressure mercury lamp. A reflector having a spheroidal reflecting surface is disposed around the light source 1. The light source 1 is disposed in the vicinity of the first focal point of the reflecting surface of the reflector, and the light emitted from the light source 1 is reflected by the reflecting surface of the reflector and collected toward the second focal point of the reflecting surface. move on.

  The color wheel 2 has a disk shape as shown in FIG. 2, and is divided into four fan-shaped regions divided along the circumferential direction, each having three color filters (red filter R, green filter G) having different transmission wavelength bands. , Blue filter B) and one transparent filter (white filter W). FIG. 3 shows the characteristics of each filter. The vertical axis of the graph shown in FIG. 3 represents transmittance (%), and the horizontal axis represents wavelength (nm). As can be seen from the graph of FIG. 3, the red filter R transmits only light in the red wavelength band (hereinafter “red light”) and reflects or absorbs light in other wavelength bands. The green filter G transmits only light in the green wavelength band (hereinafter “green light”), and reflects or absorbs light in other wavelength bands. The blue filter B transmits only light in the blue wavelength band (hereinafter “blue light”), and reflects or absorbs light in other wavelength bands. The white filter W transmits light emitted from the light source (hereinafter, “white light”) as it is, and does not reflect or absorb light in any wavelength band. The color wheel 2 is disposed in the vicinity of the second focal point of the reflector so that light collected by the reflector is incident on the color filters R, G, B and the white filter W. In addition, a rotation shaft of a motor (not shown) is directly or indirectly connected to the center of the color wheel 2, and when the motor is driven, the color wheel 2 has a constant speed in the circumferential direction with the center as the rotation center. Rotate with. As a result, the color filters R, G, B and the white filter W cross the light path of the light collected by the reflector at a constant period, and the light (white light) emitted from the light source 1 is red light, green light, It is separated into blue light and white light by time division.

  Referring again to FIG. 1, the light tunnel 3 is arranged at the tip of the color wheel 2. The light tunnel 3 is a square tube made of glass or plastic with a reflective film deposited on the inner surface, and each color light color-separated in a time division manner by the color wheel 2 is incident from one opening of the light tunnel 3. The light tunnel 3 travels while being totally reflected, and exits from the other opening. During this time, the light traveling in the light tunnel 3 is made uniform in luminance distribution in the cross section of the light beam orthogonal to the traveling direction by repeating total reflection. That is, the light tunnel 3 functions as a so-called integrator optical system.

  In this example, a holographic liquid crystal manufactured by SBGLabs was used as the electronic filter 4. As shown in FIG. 4, the electronic filter 4 transmits incident light as it is in a normal state (when OFF), but diffracts light of a specific wavelength when a predetermined voltage is applied (when ON). Has characteristics. In this example, a set of electronic filters having different specific wavelengths that are diffracted when a voltage is applied are arranged in series. Specifically, as shown in FIG. 5, when a voltage is applied, an electronic filter 4a having a characteristic of diffracting the wavelengths of the long wavelength side end of blue light and the short wavelength side end of green light; And an electronic filter 4b having a characteristic of diffracting the wavelength of the end portion on the long wavelength side of the green light and the end portion on the short wavelength side of the red light are arranged in series between the light tunnel 3 and the reflecting mirror 5. Yes. Therefore, as shown in FIG. 6, if a voltage is applied to the electronic filters 4a and 4b at the timing when the green light is extracted by the color wheel 2 (if both the electronic filters 4a and 4b are turned on simultaneously), the green light Since the wavelengths at both ends are cut and only the center wavelength is transmitted, relatively high-purity green light is incident on the reflected light 5. If a voltage is applied to the electronic filter 4a in accordance with the timing at which the blue light is extracted, a part of the blue light on the long wavelength side is cut, and the blue light having a relatively high color purity is incident on the reflected light 5. . Furthermore, if a voltage is applied to the electronic filter 4b in accordance with the timing at which red light is extracted, a part of the short wavelength side of the red light is cut and relatively high-purity red light is incident on the reflecting mirror 5. . On the other hand, if no voltage is applied to either of the electronic filters 4a and 4b, the light transmitted through the color wheel 2 passes through both the electronic filters 4a and 4b as it is, so that relatively high-intensity light is applied to the reflecting mirror 5. Incident. In addition, if a voltage is applied to the electronic filters 4a and 4b in accordance with the timing at which white light is extracted, the light passing through each of the color filters R, G, and B, the boundary between red light and green light, and green light and blue light The wavelength corresponding to the boundary with the light is cut, and white light in which RGB that has passed without being cut is synthesized is obtained. For the light that has passed through the white filter W, the wavelength corresponding to the boundary between the red light and the green light and the boundary between the green light and the blue light included therein is cut. Therefore, white light obtained by synthesizing red light, green light, and blue light separated by the color filters R, G, and B, and white light (from the light source 1) that has passed through the white filter W. The difference from the white light as it is emitted becomes small. As a result, even when color purity is important, light that has passed through the white filter W can be used, and the color purity can be improved without lowering the luminance.

  As described above, the spectral characteristics can be changed in one frame by selectively turning ON / OFF both or one of the electronic filters 4a and 4b in synchronization with the color selection timing by the color wheel 2. Further, even when a spectral characteristic with an emphasis on color purity is selected, a reduction in luminance can be minimized. The reason why such high-speed processing is possible is that the electronic filters 4a and 4b have an operation speed (response speed) of several tens to one hundred times that of polysilicon liquid crystal.

  The reflecting mirror 5 shown in FIG. 1 reflects the light transmitted through the electronic filters 4 a and 4 b and makes it incident on the reflective liquid crystal panel 6. The light reflected by the reflecting mirror 5 is irradiated almost uniformly on the front surface of the reflective liquid crystal panel 6.

  The reflective liquid crystal panel 6 spatially modulates the irradiated light in accordance with a drive signal output from a drive circuit (not shown) to form image light of each color of R, G, and B. Specifically, a drive signal is output from a drive circuit (not shown) according to an image signal input from the outside and input to the reflective liquid crystal panel 6. Then, the reflective liquid crystal panel 6 turns on / off the cell corresponding to each pixel according to the input drive signal, and forms image light according to the image signal.

  The image light of each color formed by the reflective liquid crystal panel 6 is sequentially projected onto a screen (not shown) via the projection optical system 7. As a result, the human eye looking at the screen recognizes it as a color image by the afterimage phenomenon.

(Embodiment 2)
Hereinafter, another example of the embodiment of the projector device of the present invention will be described with reference to the drawings. FIG. 7 is a schematic diagram showing a schematic configuration of the projector apparatus of this example. The projector apparatus of this example includes a light source 10, an integrator optical system 20, a polarization conversion element 30, dichroic mirrors 40a to 40c, electronic filters 50, 60, and 70, total reflection mirrors 80a and 80b, and transmissive liquid crystal. Panels 90a to 90c, a cross dichroic prism 100, and a projection optical system 110 are provided.

  The light source 10 is the same as the light source 1 shown in FIG. 1, and a reflector is disposed around it. The integrator optical system 20 includes a first lens array 20a and a second lens array 20b. The first lens array 20a and the second lens array 20b are composed of a plurality of minute condensing lenses, the first lens array 20a forms a secondary light source image, and the second lens array 20b An image of each condensing lens constituting one lens array 20a is formed.

  The polarization conversion element 30 rotates the polarization direction of either S-polarized light or P-polarized light included in the light emitted from the second lens array 20b to align it with S-polarized light or P-polarized light.

  The dichroic mirror 40a transmits only red light out of the incident light and makes it enter the electronic filter 50, and reflects other color light and makes it incident on the dichroic mirror 40b. Of the incident light, the dichroic mirror 40b reflects only the green light to be incident on the electronic filter 60, and transmits the other color light to be incident on the dichroic mirror 40c. The dichroic mirror 40 c reflects only the blue light of the incident light and makes it incident on the electronic filter 70. As described above, the light (white light) emitted from the light source 10 is separated into red light, green light, and blue light, and enters the corresponding electronic filters 50, 60, and 70, respectively.

  The electronic filter 50 on which the red light transmitted through the dichroic mirror 40a is incident is composed of a pair of electronic filters 50a and 50b arranged in series on the optical path of the red light. The electronic filter 60 on which the green light reflected by the dichroic mirror 40b enters is composed of a pair of electronic filters 60a and 60b arranged in series on the optical path of the green light. Further, the electronic filter 70 on which the blue light reflected by the dichroic mirror 40c is incident is composed of a pair of electronic filters 70a and 70b arranged in series on the optical path of the blue light. These multiple electronic filters are common in that they transmit the incident light as it is in the normal state (when OFF), but diffract light of a specific wavelength when a predetermined voltage is applied (when ON). doing. However, each electronic filter has a different wavelength of light to be diffracted when a voltage is applied. Specifically, the electronic filter 50a diffracts the end wavelength on the short wavelength side of red light, and the electronic filter 50b diffracts the end wavelength on the long wavelength side of red light. The electronic filter 60a diffracts the end wavelength on the short wavelength side of the green light, and the electronic filter 60b diffracts the end wavelength on the long wavelength side of the green light. Further, the electronic filter 70a diffracts the end wavelength on the short wavelength side of the blue light, and the electronic filter 70b diffracts the end wavelength on the long wavelength side of the blue light. Therefore, for example, when a voltage is applied to the electronic filters 50a and 50b, the short wavelength side and long wavelength side ends of the red light are cut, and only the center wavelength is transmitted. On the other hand, if no voltage is applied to the electronic filters 50a and 50b, all the wavelengths of red light transmitted through the dichroic mirror 40a are transmitted through the electronic filters 50a and 50b. As a result, when the electronic filters 50a and 50b are turned on, the color purity of red light is improved, and when the electronic filters 50a and 50b are turned off, the luminance is improved. The same applies to green light and blue light.

  The total reflection mirror 80a reflects the red light transmitted through the electronic filters 50a and 50b and makes it incident on the transmissive liquid crystal panel 90a. Further, the total reflection mirror 80b reflects the blue light transmitted through the electronic filters 70a and 70b and makes it incident on the transmissive liquid crystal panel 90c. Note that the green light transmitted through the electronic filters 60a and 60b is directly incident on the transmissive liquid crystal panel 90b.

  The transmissive liquid crystal panels 90a to 90c spatially modulate the incident light in accordance with the image signal to form image light of each color. The formed image light of each color is incident from a predetermined incident surface of the cross dichroic prism 100 determined in advance for each color, and is synthesized in the prism 100 to become full-color image light, and is emitted from a predetermined emission surface. Exit. The full-color image light emitted from the cross dichroic prism 100 is projected on a screen (not shown) via the projection optical system 110.

(Other embodiments)
By adopting the electronic filters 50, 60, and 70 shown in FIG. 7 in place of the electronic filter 4 shown in FIG. 1, not only green light but also blue light and red light are both short wavelength side and long wavelength side. The end of can be cut. In this case, the color purity of each color is further improved.

  Further, the electronic filter shown in FIGS. 1 and 7 can be replaced with an electronic filter having a plurality of wavelength bands that can be diffracted when a voltage is applied, and a structure in which these different diffraction wavelength bands can be electrically switched. In this case, since the central wavelength of two or more color lights can be extracted with one electronic filter, the above-described effects can be obtained with fewer electronic filters.

  So far, the embodiment of the present invention has been described by taking the case where the spatial light modulation means is a liquid crystal panel as an example. However, the spatial light modulation means using DMD (Digital Micro-mirror Device) and other means are described. It can also be changed.

It is a schematic diagram which shows an example of embodiment of the projector apparatus of this invention. It is a schematic diagram which shows the structure of the color wheel of FIG. It is a figure which shows the characteristic of the color wheel of FIG. It is a schematic diagram which shows the effect | action of the electronic filter of FIG. It is a schematic diagram which shows the arrangement | positioning state of the two electronic filters shown in FIG. It is a figure which shows the characteristic of the electronic filter shown in FIG. It is a schematic diagram which shows the other example of embodiment of the projector apparatus of this invention. It is a schematic diagram which shows the outline of the conventional single plate type liquid crystal projector. FIG. 10 is a schematic diagram showing an outline of a liquid crystal projector device disclosed in Patent Document 1. It is a schematic diagram which shows the switching means currently disclosed by patent document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 10 Light source 2 Color wheel 3 Light tunnel 4 Electronic filter 5 Reflective mirror 6 Reflective liquid crystal panel 7, 110 Projection optical system 20 Integrator optical system 30 Polarization conversion element 40 Dichroic mirror 50 Electronic filter 60 Electronic filter 70 Electronic filter 80 Total reflection Mirror 90 Transmission type liquid crystal panel 100 Cross dichroic prism

Claims (5)

A light source, time-division color separation means for separating the light emitted from the light source into red light, green light, and blue light in a time-division manner, and image light by modulating each color light separated by the time-division color separation means And a projection optical system for projecting image light formed by the spatial light modulation means,
On the optical path from the light source to the spatial light modulation means, it is possible to electrically switch between the operating state and the non-operating state, and in the operating state, a part of the short wavelength side of the incident light and the long wavelength A projector device provided with an electronic filter that diffracts both or one side of the side to the outside of the optical path, transmits other light, and transmits all incident light when not in operation.   The projector device according to claim 1, wherein the electronic filter is disposed between the time-division color separation unit and the spatial light modulation unit. A light source, two or more color separation means for separating light emitted from the light source into red light, green light, and blue light, respectively, and modulating each color light separated by each color separation means to form image light 2 The above spatial light modulation means, a synthesis means for synthesizing image light of two or more colors formed by each spatial light modulation means, and a projection optical system for projecting the image light synthesized by the synthesis means In the projector device,
On the optical path from the light source to the spatial light modulation means, it is possible to electrically switch between the operating state and the non-operating state, and in the operating state, a part of the short wavelength side of the incident light and the long wavelength A projector device provided with an electronic filter that diffracts both or one side of the side to the outside of the optical path, transmits other light, and transmits all incident light when not in operation.   4. The projector apparatus according to claim 3, wherein the electronic filter is disposed on an optical path of each color light separated by each color separation means.   The projector device according to any one of claims 1 to 4, wherein two or more types of electronic filters having different wavelength bands of light to be diffracted in an operating state are arranged in series.

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