JP2015172615A - Color wheel and projection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To change color configuration arbitrarily, and improve both of brightness and color reproducibility.SOLUTION: A color configuration adjustment section 73 selects whether each of color components of a color wheel 60 is colored, transparent, or middle thereof, on the basis of an instruction from a video analysis section 72 or a mode selection section 73, and outputs a selection signal to a power supply section 63. The power supply section 63 generates an AC rectangular wave signal with appropriately adjusted voltage, according to the selection signal input from the color configuration adjustment section 73. Power is supplied from power lines 64a, 64b to supply electrodes 65a, 65b arranged in a rotation shaft of the color wheel 60. In the color wheel 60, the rotation shaft is rotated by a rotation drive mechanism. The AC rectangular wave signals supplied from the supply electrodes 56a, 65b are applied to transparent electrodes 61c, 61e.

Description

  The present invention relates to a DLP projection apparatus, and more particularly to a color wheel having a configuration in which the transmittance of color components can be changed, and a projection apparatus.

Conventionally, a projector employs a liquid crystal system, a DLP system, an LCOS (Liquid Crystal On Silicon) system, and the like.
First, the internal configuration of a conventional DLP projector 100 will be described with reference to FIG.
The white light 102 emitted from the light source 101 is colored by passing through the color wheel 103 that rotates at high speed. The light 104 transmitted through the color wheel 103 enters a DMD unit (Digital Micromirror Device) 105. Here, in the DMD unit 105 in which minute mirrors corresponding to the number of pixels are arranged, reflection / non-reflection is selected by ON / OFF control, and the light 106 reflected by the DMD unit 105 passes through the optical system 107 to the screen ( (Not shown) to form a projected image.

Next, a conventional DLP color wheel will be described with reference to FIG.
There are various variations in the color wheel color scheme, and as shown in FIG. 14A, the color wheel 103A composed of only the three primary colors of RGB or the brightness of the projected image as shown in FIG. 14B is increased. There is also a color wheel 103B that adds white, cyan, and yellow in addition to the RGB three primary colors.
Compared with the liquid crystal system, the DLP system has an advantage that black and white contrast is high because the light source itself is turned off in black display. In addition, it has advantages such as light weight, small size, and little deterioration over time.
However, the DLP method has a disadvantage that the brightness is lower than that of the liquid crystal method due to the time-division driving of each color.

In the DLP method, Patent Documents 1 to 5 are disclosed in order to improve both the brightness and the color reproduction range of a projected image, and a proposal is made to use a plurality of color filters depending on the application. However, when a plurality of color wheels are used, there is a problem that it is disadvantageous for downsizing.
Patent Document 1 includes a color filter having at least a blue light transmission region, a red light transmission region, and a green light transmission region, and a unit case that rotatably stores the color filter. A modular color wheel device is disclosed that includes a first light transmission region for allowing light to enter the light source and a second light transmission region for emitting light from the color filter.
Patent Document 2 discloses a projector apparatus having a projector lamp, a plurality of color wheels provided on an optical path from the projector lamp, and a control unit that controls a combination of color filters on the optical path of the plurality of color wheels. Has been.

  Patent Document 3 discloses an image using a light source, a color wheel unit having a color wheel in which color filters for arranging light from the light source are arranged in the circumferential direction, and light arranged by the color wheel. In a projector apparatus that obtains an enlarged image by projecting an image formed by the image forming element, the color wheel unit is composed of a plurality of color wheels, and is used for switching between the plurality of color wheels. The color switch further includes color wheel switching means for alternately switching these color wheels, and the plurality of color wheels have a color arrangement of color filters capable of reproducing different brightness and color, Multiple color wheels can be set manually or automatically by dial switch or external switch. Ri projector apparatus, wherein the changing is disclosed.

  Patent Document 4 discloses a projector including a light source device, a light source side optical system, a display element, a projection side optical system, a cooling fan, a lamp power supply circuit, a fan drive power supply circuit, and projector control means, including a red filter, A color wheel that has two color wheels of four colors that are transparent or white filters added to the three primary colors of the green filter and blue filter, and the transparent or white filters of the two color wheels are stacked on the optical path. A projector is disclosed that includes a wheel motor that rotates one of two color wheels based on a position.

  Patent Document 5 includes a lamp, a red, green, blue, colorless and transparent color filter, and a first color wheel that time-divides light emitted from the lamp, and an output from the first color wheel. A rod-type integrator that emits light as planar light, and a red, green, blue, colorless and transparent color filter, which is arranged coaxially with the first color wheel, and emits light from the integrator. A second color wheel for time division, a first and a second motor disposed on the integrator side of the first and second color wheels and driving the first and second color wheels, respectively, and a second color A doublet lens that expands the light emitted from the wheel, a mirror that reflects the light emitted from the doublet lens, a relay lens that magnifies the light reflected from the mirror, and a plurality of mirror elements And a mirror that can individually control each mirror element and modulates light emitted from the relay lens into image light, and a projection lens that projects image light from the digital mirror device A projector equipped with an engine, wherein the first and second color wheels are arranged so that the light spot diameters on the first and second color wheels are the same, and the two color wheels have the same color on the optical path. There is disclosed a presentation mode in which the color filters are rotated so that the color filters overlap each other, and a color wheel in which both color wheels are colorless and transparent with red, green, and blue color filters on the optical path.

  Patent Document 6 discloses a lighting device that constantly emits light of one specific color among light of RGB colors aligned in a predetermined polarization state, and switches and emits light of the other two colors in a time-sharing manner, The first specific wavelength polarization conversion device that converts one of the polarization directions so that the polarization direction of the light of one specific color and the polarization direction of the other two colors of light are different from each other. A polarizing beam splitter that separates light of one specific color and light of the other two colors, a first reflective liquid crystal light valve that modulates and reflects the separated light of the specific color for each pixel, A second reflective liquid crystal light valve that modulates and reflects the other two separated colors of light for each pixel, and a specific one-color light from the first reflective liquid crystal light valve; , The other two colors of light from the second reflective liquid crystal light valve, and a polarization beam splitter Display optical apparatus is disclosed which is characterized in that is synthesized and projected by.

Patent Document 7 discloses a light source that emits white light, a light source control unit that controls the light source, and red light that transmits light in the red wavelength band, the green wavelength band, and the blue wavelength band of white light emitted from the light source. A color wheel having a filter, a green filter and a blue filter, a rotation control unit for rotating the color wheel, an optical modulator for modulating light of each wavelength band transmitted through the color wheel, and an optical modulator based on the video signal A modulation control unit that controls the light modulator to drive the light modulator in synchronization with the rotation of the color wheel so that the corresponding light modulation is performed on the light of each wavelength band, and the light source control unit The image projection device is characterized in that the light source is controlled so that the emission intensity when the white light enters the red filter and the green filter is higher than when the white light enters the blue filter. It is shown.
Also, the trouble of manually replacing a plurality of color wheels remained.

As described above, Patent Documents 1 to 5 are disclosed in order to improve both the brightness of the projected image and the color reproduction range, and a proposal has been made to use a plurality of color filters depending on the application. However, when a plurality of color wheels are used, there is a problem that it is disadvantageous for downsizing.
In Patent Document 6, a cholesteric liquid crystal is used for a liquid crystal type (non-DLP type) light valve, and the reflectance and transmittance of each color of GB are switched in a time-sharing manner to achieve miniaturization.
Further, Patent Document 7 attempts to adjust the intensity of the light source in synchronization with the timing of each color of the color wheel in order to adjust the white balance and the color reproduction range appropriately in the projection device using the color wheel. .
Therefore, a proposal of a color wheel having a single configuration that can change the color configuration arbitrarily and enables both brightness and color reproducibility of the projected image is desired.
SUMMARY OF THE INVENTION The present invention has been made in view of the above, and as its purpose, a color wheel having a single configuration that can change the color configuration arbitrarily, and can achieve both brightness and color reproducibility of a projected image, and a projection device. It is to provide.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a color wheel that includes a plurality of color regions arranged in the rotation direction and generates light of different color components by transmitting light to each color region. And at least 1 said color area | region consists of a some translucent layer, and at least 1 translucent layer is a transmittance | permeability changeable member which can change the transmissivity, It is characterized by the above-mentioned.

  According to the present invention, at least one color region of the color wheel is composed of a plurality of light-transmitting layers, and the at least one light-transmitting layer is a transmittance variable member that can change the transmittance, whereby one color wheel. The color composition can be arbitrarily changed with, and both the brightness of the projected image and the color reproducibility can be achieved.

(A) (b) is a conceptual diagram which shows the optical characteristic of the cholesteric liquid crystal which is the principle of this invention. (A) (b) is a figure which shows the optical characteristic of the transmission spectrum of the planar state of a cholesteric liquid crystal which is the principle of this invention, and a focal conic state. It is the schematic diagram (the 1) which shows the structure which laminated | stacked the two cholesteric liquid crystals which are the principles of this invention. FIG. 6 is a schematic diagram (No. 2) showing a configuration in which two cholesteric liquid crystals that are the principle of the present invention are stacked. (A) (b) is a figure which shows the optical characteristic of the spectrum of two types of cholesteric liquid crystals which are the principles of this invention shown in FIG.3 and FIG.4. It is a figure which shows the top view of the color wheel which concerns on 1st Embodiment of this invention. It is a figure which shows the top view of the color wheel which concerns on 2nd Embodiment of this invention. It is a figure which shows the top view of the color wheel which concerns on 3rd Embodiment of this invention. It is a figure which shows the top view of the color wheel which concerns on 4th Embodiment of this invention. It is sectional drawing of the color wheel which concerns on 5th Embodiment of this invention. It is a block diagram of the projector which concerns on 5th Embodiment of this invention. It is a flowchart showing the control operation of the projector which concerns on 5th Embodiment of this invention. It is a block diagram of a conventional DLP projector. (A) (b) is a figure which shows the top view of the conventional color wheel of a DLP system.

  According to the embodiment of the present invention, in the color wheel used in the DLP projector, the color component transmittance in one color wheel can be changed, and the color configuration of the color wheel is suitable for the projection mode and the video information. A cholesteric liquid crystal is used as a color material that can change the transmittance, and the transmittance is controlled by a voltage applied to the cholesteric liquid crystal.

The principle of the present invention will be described below with reference to the drawings.
<Principle 1>
The present invention makes it possible to change both the brightness and color reproducibility of the projected image without using two color wheels as in the prior art, by making it possible to change the transmittance of the color components formed by one color wheel. Technology. A cholesteric liquid crystal is used as one configuration for changing the transmittance of the color wheel.
1 to 5 and Table 1 show optical characteristics of the cholesteric liquid crystal. A cholesteric liquid crystal has two stable modes, a planar state and a focal conic state, and these states can be maintained without applying a voltage.

The optical characteristics of the cholesteric liquid crystal 10 that is the principle of the present invention will be described with reference to the conceptual diagrams shown in FIGS. In FIGS. 1A and 1B, the vertical direction of the paper surface is treated as the y-axis, and the horizontal direction of the paper surface is treated as the x-axis. FIG. 1A is a conceptual diagram showing that a cholesteric liquid crystal is in a planar state having selective reflection characteristics.
In FIG. 1A, a cholesteric liquid crystal 10a is formed of liquid crystal molecules having a spiral structure between an upper layer substrate 1 made of a transparent material, a lower layer substrate 3 made of a transparent material, and the upper layer substrate 1 and the lower layer substrate 3. And a cholesteric liquid crystal layer 5a.

Here, general properties of the cholesteric liquid crystal will be described.
The cholesteric liquid crystal has a characteristic of “selective reflection” in which the arrangement of liquid crystal molecules forms a helical structure and reflects light (that is, the color changes) according to the helical pitch.
A cholesteric liquid crystal has a layered structure in which rod-shaped molecules are stacked several times. Within each layer, each molecule is arranged in a certain direction, and each layer is accumulated so that the molecules are arranged in a spiral. doing. Usually, the direction perpendicular to the substrate is the spiral axis (y-axis direction) and has a spiral structure with a constant period. Reflects circularly polarized light having the same period and wavelength as the helix and in the same direction as the helix.
The material for the cholesteric liquid crystal may be an oligomer, a polymer, or a mixture thereof.
This cholesteric liquid crystal is formed by sandwiching a cholesteric liquid crystal between two transparent electrodes, and takes a stable state of a planar state or a focal conic state depending on the value of a pulse voltage applied between both transparent electrodes. . After applying a high pulse voltage, the state transitions to the planar state, and selectively reflects color light according to the helical pitch of the cholesteric liquid crystal. After application of a low pulse voltage, a transition is made to the focal conic state. In addition, when a high pulse voltage is applied, the light enters a homeotropic state and the light transmittance increases. When the voltage is suddenly released from this state, it changes to a planar state.

In the cholesteric liquid crystal layer 5a, the liquid crystal molecules form a spiral structure, and when the spiral axis of the spiral structure is perpendicular (y-axis direction) to the plane (x-axis direction) of the cholesteric liquid crystal, that is, the spiral axis is the upper layer. When the substrate 1 and the lower substrate 3 are perpendicular (y-axis direction), a planar state is obtained. In the planar state, a specific wavelength band is selectively reflected with respect to the incident white light 7.
In FIG. 1A, the green component light 8 is selectively reflected with respect to the incident white light 7, and the magenta component light 9 which is the remaining component of the white light is transmitted.
The wavelength band for selective reflection can be controlled by the helical pitch. When the helical pitch is smaller than this state, the blue component is selectively reflected, and when the helical pitch is larger than this time, the red component is selectively reflected.

On the other hand, FIG. 1B is a conceptual diagram showing that the cholesteric liquid crystal is in a focal conic state having transmission characteristics.
In FIG. 1B, a cholesteric liquid crystal 10b includes an upper layer substrate 1, a lower layer substrate 3, and a cholesteric liquid crystal layer 5b. As shown in FIG. 1B, the cholesteric liquid crystal 10b is formed when the spiral axis of the spiral structure is parallel to the plane (x-axis direction) of the cholesteric liquid crystal, that is, the spiral axis of the liquid crystal molecules is the upper substrate 1 and the lower layer. When the substrate 3 is horizontal (x-axis direction), a focal conic state is established, and the incident white light 7 is almost transmitted.

The planar state and the focal conic state of the cholesteric liquid crystal, which is the principle of the present invention, will be described with reference to the optical characteristics of the transmission spectrum shown in FIG. 2A shows the planar state (FIG. 1A), and FIG. 2B shows the focal conic state (FIG. 1B). In FIGS. 2A and 2B, the vertical axis indicates the transmittance, and the horizontal axis indicates the wavelength.
As shown in FIG. 2A, a specific reflection band is selectively reflected in the planar state. Specifically, in the planar state, since the reflected light is right circularly polarized light or left circularly polarized light, the upper limit of the reflectance is theoretically 50%, and the transmitted light is the remaining circularly polarized light. Theoretically 50%.
As shown in FIG. 2B, in the focal conic state, as described with reference to FIG. 1B, high transmittance is exhibited over the entire wavelength band.
Here, right circularly polarized light and left circularly polarized light will be described.
Natural light includes right circularly polarized light and left circularly polarized light. When only right circularly polarized light is selectively reflected by the action of a cholesteric liquid crystal layer that selectively reflects incident light, this reflected light is This is called polarized light, and the cholesteric liquid crystal layer at this time is called an R body. On the other hand, when only the left circularly polarized light is selectively reflected, this reflected light is called left circularly polarized light, and the cholesteric liquid crystal layer at this time is called an L body.
Note that the helical pitch and the polarization state can be arbitrarily adjusted by the addition rate of the chiral material contained in the cholesteric liquid crystal.

<Principle 2>
A configuration in which two cholesteric liquid crystals that are the principle of the present invention are stacked will be described with reference to a schematic diagram shown in FIG. FIG. 3 is a schematic diagram (part 1) showing a configuration in which two cholesteric liquid crystals are stacked.
In the explanation of the principle 1, the configuration example using the cholesteric liquid crystal 10a of one layer as the cholesteric liquid crystal has been exemplified. However, the present invention is not limited to the cholesteric liquid crystal 10a of one layer. For example, the cholesteric liquid crystals 10a1, 10a2 of two layers are used. It is possible to provide.
The principle explanation 2 is different from the principle explanation 1 having the one-layer cholesteric liquid crystal 10a in that the two-layer cholesteric liquid crystals 10a1 and 10a2 have different directions of circularly polarized light.
As shown in FIG. 3, in the principle explanation 2, the first layer 10a1 that reflects the green component and the second layer 10a2 that reflects the blue component are laminated, and the helical pitch of the liquid crystal molecules of the cholesteric liquid crystal layer 5a1 and the cholesteric The feature is that the pitch is different from the spiral pitch of the liquid crystal molecules of the liquid crystal layer 5a2.
In FIG. 3, since the green light 8a is reflected in the first layer 10a1 and the blue light 8b is reflected in the second layer 10a2 with respect to the incident white light 7, the component of the transmitted light 9 is mainly Red component.

<Principle 3>
A configuration in which two cholesteric liquid crystals that are the principle of the present invention are stacked will be described with reference to a schematic diagram shown in FIG. FIG. 4 is a schematic diagram (part 2) showing a configuration in which two cholesteric liquid crystals are laminated.
In the principle explanation 2, a configuration example is shown in which the spiral pitch of the liquid crystal molecules of the cholesteric liquid crystal layer 5a1 is different from the spiral pitch of the liquid crystal molecules of the cholesteric liquid crystal layer 5a2, but the present invention is different in pitch. For example, two layers of cholesteric liquid crystals 10a1 and 10a3 having different twist directions of liquid crystal molecules can be provided.
As shown in FIG. 4, in the principle explanation 3, the first layer 10a1 and the second layer 10a3 are laminated, and the twist direction of the liquid crystal molecules of the cholesteric liquid crystal layer 5a1 and the twist direction of the liquid crystal molecules of the cholesteric liquid crystal layer 5a3. Features a different direction.
As shown in FIG. 4, a first layer 10a1 that selectively reflects right circularly polarized light (R-shaped body) and a second layer 10a3 that selectively reflects left circularly polarized light (L-shaped body) are stacked with the same reflection wavelength. is there.
In FIG. 4, with respect to incident white light, the first layer 10a1 that is the upper layer has right-hand circularly polarized light (R body) of the green component, and the second layer 10a3 that is lower layer has left-hand circularly polarized light (L body). Therefore, the magenta color component transmitted through the first layer 10a1 and the second layer 10a3 has a characteristic point that the color purity is higher (the saturation is higher).
As described above, the cholesteric liquid crystal layer is formed by laminating a plurality of layers formed of cholesteric liquid crystals, and each layer can be set to a higher saturation because the wavelength of reflected light and the wavelength of polarized light are different.

With reference to the spectrum diagrams shown in FIGS. 5A and 5B, the optical characteristics of the two types of cholesteric liquid crystals, which are the principles of the present invention shown in FIGS. 3 and 4, will be described. 5A shows the spectral characteristics when red is transmitted by the laminated structure shown in FIG. 3, and FIG. 5B shows the spectral characteristics when magenta color is transmitted by the laminated structure shown in FIG. In FIGS. 5A and 5B, the vertical axis indicates the transmittance, and the horizontal axis indicates the wavelength.
In particular, it can be understood that the transmittance of the green component shown in FIG. 5B is cut more suitably than the notch characteristic shown in FIG.

  Table 1 summarizes the optical characteristics of the cholesteric liquid crystal described above.

As shown in Table 1, in the planar state, the reflected light and the transmitted light have a complementary color relationship.
In addition to the planar state and the focal conic state, there are also homeotropic states. In the homeotropic state, similarly to the focal conic state, the helical axis of the helical structure is parallel to the plane (x-axis direction) of the cholesteric liquid crystal.
In the planar state or the focal conic state, the state can be maintained without applying a voltage, whereas in the homeotropic state, the state can be maintained only while a high voltage (V _H ) is applied. it can.
When the high voltage (V _H ) forming the homeotropic state is suddenly lowered to 0 V, the state shifts to the planar state, and when the high voltage (V _H ) forming the homeotropic state is gradually decreased, the state shifts to the focal conic state. .
Further, by applying a voltage (V _C ) in an intermediate state between the planar state and the focal conic state, the planar state and the focal conic state can be finely mixed, and the optical characteristics can be intermediate between the two. it can.
Therefore, if the voltage applied to the two transparent electrodes parallel to the cholesteric liquid crystal is an AC rectangular wave signal that can be supplied by switching between the low voltage VL and the high voltage VH (V _L <V _C <V _H ), it is homeotropic. The state (V _H ), the focal conic state (V _C ), and the planar state (V _L ) can be switched. Although the applied voltage differs depending on the material of the cholesteric liquid crystal, the high voltage V _H is preferably about 30 V to 35 V, for example, but the present invention is not limited to such a voltage range.
The voltages applied to the cholesteric liquid crystal are classified into three groups of V _L and V _C, V _C and V _{H, and} V _L and V _H , so that the homeotropic state (V _H ) and the focal conic state (V _C ), A mode for switching the planar state (V _L ) can be configured. Thereby, the ratio of emphasizing color reproducibility and brightness can be finely set by the applied voltage.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
With reference to the top view shown in FIG. 6, the color wheel which concerns on 1st Embodiment of this invention is demonstrated.
In the conventional color wheel shown in FIG. 13B, since the color region of the color wheel uses dyes or pigments, the optical characteristics are fixed.
On the other hand, FIG. 6 shows a color wheel 20 according to this embodiment of the present invention, which has six segments 20g, 20y, 20r, 20w, 20c, and 20r.
In the color configuration forming the color wheel 20, an example is shown in which the segment 20c of the cyan color region (C) and the segment 20y of the yellow color region (Y) are replaced with cholesteric liquid crystals (transmissivity changeable members).
A plurality of variations can be provided in the color region of one color wheel by replacing the segment of the cyan region and the yellow region with a cholesteric liquid crystal.
As described above, the color wheel includes a plurality of color regions arranged in the rotation direction and generates light of different color components by transmitting light to the individual color regions, and at least one color region includes a plurality of color regions. The at least one light transmissive layer is a cholesteric liquid crystal whose transmittance can be changed, so that the color configuration can be arbitrarily changed by one color wheel.

Second Embodiment
With reference to the top view shown in FIG. 7, the color wheel which concerns on 2nd Embodiment of this invention is demonstrated.
In the first embodiment, the configuration example in which the segment 20c in the cyan color region (C) and the segment 20y in the yellow color region (Y) are replaced with cholesteric liquid crystal is illustrated, but the present invention is not limited to cholesteric liquid crystal. For example, the cholesteric liquid crystal can be in a planar state.
As shown in FIG. 7, in the second embodiment, the color wheel 30 has six segments 30g, 30y, 30r, 30w, 30c, 30r, and a cyan region segment 30c and a yellow region segment 30y. Is a planar state.
As shown in FIG. 7, when the segment of the cyan region and the segment of the yellow region formed using cholesteric liquid crystal are in the planar state, both regions are colored. Suitable for important video.

<Third Embodiment>
With reference to the top view shown in FIG. 8, the color wheel which concerns on 3rd Embodiment of this invention is demonstrated.
In the first embodiment, the configuration example in which the segment 20c in the cyan color region (C) and the segment 20y in the yellow color region (Y) are replaced with cholesteric liquid crystal is illustrated, but the present invention is not limited to cholesteric liquid crystal. For example, the cholesteric liquid crystal can be in a focal conic state.
As shown in FIG. 8, in the third embodiment, the color wheel 40 has six segments 40g, 40y, 40r, 40w, 40c, and 40r, and a cyan region segment 40c and a yellow region segment 40y. Is a focal conic state.
When the cyan and yellow areas formed using cholesteric liquid crystals are in the focal conic state, light is transmitted through both areas, so the efficiency of using white light from the light source increases, and documents, presentations, etc. This is suitable for images that emphasize brightness.

<Fourth embodiment>
With reference to the top view shown in FIG. 9, the color wheel which concerns on 4th Embodiment of this invention is demonstrated. FIG. 9 is a top view of the color wheel according to the second embodiment of the present invention.
In the first embodiment, for example, in the red region segment 20r, a configuration example in which a single color region having a homogeneous color characteristic is occupied is illustrated. However, the present invention is not limited to a single color region. It is possible to divide a certain one-color area into two or a plurality of segments and to alternately allocate (switch) the planar state and the focal conic state to each segment.
As shown in FIG. 9, in the fourth embodiment, the color wheel 50 has eleven segments 50g1, 50g2, 50y1, 50y2, 50r1, 50r2, 50w, 50c1, 50c2, 50r1, and 50r2. The feature is that the area is divided into two segments, and a planar state and a focal conic state are alternately allocated to each segment. Since the segment 50w is a white region, it is the same as the segment 20w employed in the first embodiment.

When the segment of each color area formed using cholesteric liquid crystal is in a planar state, both areas are colored, which is suitable for an image that emphasizes color reproducibility such as an animation or a movie. On the other hand, when the segments of each color region formed using cholesteric liquid crystal are in the focal conic state, both regions transmit light, so the utilization efficiency of white light from the light source increases, and documents, presentations, etc. This is suitable for images that emphasize brightness.
As a result, the cholesteric liquid crystal is colored when in the planar state and becomes transparent when in the focal conic state or homeotropic state, so that it can be used in two ways: color reproducibility and brightness.
Thereby, the ratio of emphasizing color reproducibility and brightness can be finely set by the applied voltage.

<Other variations>
Apart from the configuration examples shown in the first to fourth embodiments, the following configuration may be adopted as the color wheel of the present invention.
(1) By setting the R and L bodies of the cholesteric liquid crystal so as to be stacked in the rotation axis direction, higher saturation can be set.
(2) A multi-primary color can be set by arranging a segment of a magenta color region or another intermediate color region segment on the color wheel.
(3) Setting according to video information by dynamically changing the color configuration of the color wheel based on video information input to the projector from an information processing device such as a personal computer PC or portable terminal. It can be.
With the configurations (1) to (3) described above, a variety of color designs can be realized with one color wheel.

<Fifth Embodiment>
A color wheel according to a fifth embodiment of the present invention will be described with reference to a cross-sectional view shown in FIG. FIG. 10 is a cross-sectional view of a color wheel according to a fifth embodiment of the present invention.
In the first to fourth embodiments, for example, a configuration example related to a segment of each color region is illustrated with reference to a top view of the color wheel. However, the present invention is not limited to the segment configuration of each color region, for example, cholesteric By applying a voltage to the liquid crystal layer, each segment can be configured to switch between a planar state and a focal conic state.
As shown in FIG. 10, in the fifth embodiment, the color wheel 60 includes a plurality of light-transmitting layers such as a base substrate 61a, a transparent substrate 61b, a transparent electrode 61c, a cholesteric liquid crystal layer 61d, a transparent electrode 61e, and a transparent substrate 61f. It is characterized by being configured to be laminated from the lower layer to the upper layer. Further, the color wheel 60 is characterized by having a rotation shaft 62 at the center of the color wheel 60.
In order to switch the planar state and the focal conic state with respect to the cholesteric liquid crystal layer formed on the substrate of the color wheel 60, a transparent electrode 61e is provided above the cholesteric liquid crystal layer 61d, and a transparent electrode 61c is provided below the cholesteric liquid crystal layer 61d. I have. Enamel wires are connected to the transparent electrodes 61c and 61e from supply electrodes 65a and 65b provided on the end face of the rotary shaft 62, respectively. Brushes 64a and 64b are slidably in contact with the outer surfaces of the supply electrodes 65a and 65b, and an AC rectangular wave is applied to the brushes 64a and 64b from the power supply unit 63, respectively.
As described above, the color wheel includes a plurality of color regions arranged in the rotation direction, and the color wheels 20, 30, 40, and 50 generate light of different color components by transmitting light to the individual color regions. The at least one color region is composed of a plurality of light-transmitting layers, and the at least one light-transmitting layer is a cholesteric liquid crystal 61d whose transmittance can be changed.
As a result, the color configuration can be arbitrarily changed with one color wheel.
Thus, the transmittance can be changed by applying a voltage between the two layers sandwiching the cholesteric liquid crystal layer in a plane parallel to the rotation direction of the rotating body.

Next, a block configuration of the projector 70 according to the fifth embodiment of the present invention will be described with reference to the block diagram shown in FIG. FIG. 11 is a block diagram of a projector 70 according to the fifth embodiment of the present invention.
The video memory 71 shown in FIG. 11 has a frame memory, stores the frame data of the video to be projected, and outputs it to the video analysis unit 72 at the frame rate.
The video analysis unit 72 reads frame data from the video memory 71, analyzes what luminance distribution and color component the projected video has, and determines the color configuration of the color wheel 60 based on the analysis result. decide.
In the video analysis unit 72, for example, if the frame data is monochrome, primary colors such as RGB are not necessary, so all the cholesteric liquid crystals are switched to the focal conic state (or homeotropic state) to increase the amount of white light transmitted from the light source. Change to a brightness priority mode that emphasizes brightness. On the contrary, in the video analysis unit 72, when the frame data uses a lot of colors such as animation or movie, the cholesteric liquid crystal is switched to the planar state, and the saturation priority mode is set to emphasize color reproducibility.
Further, the mode selection unit 74 has an operation switch provided in, for example, a case of the projector. Output. The mode selection unit 74 displays one of a luminance priority mode indicating that priority is given to the luminance adjustment of the projected video and a saturation priority mode indicating priority to the saturation adjustment of the projected video when the user needs. Select and input as a mode.

The color configuration adjustment unit 73 selects whether each color component of the color wheel 60 is colored or transparent based on an instruction from the video analysis unit 72 or the mode selection unit 73, and outputs a selection signal to the power supply unit 63. Is done.
The power supply unit 63 generates an AC rectangular wave signal whose voltage is appropriately adjusted according to the selection signal input from the color configuration adjustment unit 73, and supplies power to the rotation shaft of the color wheel 60 from the power supply lines 64 a and 64 b. Power is supplied to the electrodes 65a and 65b.
The power supply unit 63 can generate the voltages applied to the cholesteric liquid crystal by classifying them into three sets of V _L and V _C, V _C and V _{H, and} V _L and V _H , and the homeotropic state (V _H ), The voltage configuration can be set in accordance with the mode for switching between the focal conic state (V _C ) and the planar state (V _L ). Thereby, the ratio of emphasizing color reproducibility and brightness can be finely set by the applied voltage.
The color wheel 60 has a rotating shaft rotated by a rotation drive mechanism (not shown), and an AC rectangular wave signal fed from the supply electrodes 56a and 65b is applied to the transparent electrodes 61c and 61e.
On the other hand, the white light 82 emitted from the light source 81 is colored by passing through the color wheel 60 that rotates at high speed. The light 84 transmitted through the color wheel 60 enters the DMD unit 85. Here, in the DMD unit 85 in which minute mirrors corresponding to the number of pixels are arranged, reflection / non-reflection is selected by the ON / OFF control, and the light 86 reflected by the DMD unit 85 passes through the optical system 87 to the screen ( (Not shown) to form a projected image.

A control operation of the projector 70 according to the fifth embodiment of the present invention will be described with reference to the flowchart shown in FIG.
First, in FIG. 11, the white light 82 emitted from the light source 81 is colored by passing through the color wheel 60 that rotates at high speed. The light 84 transmitted through the color wheel 60 enters the DMD unit 85.
Here, in the DMD unit 85 in which minute mirrors corresponding to the number of pixels are arranged, reflection / non-reflection is selected by the ON / OFF control, and the light 86 reflected by the DMD unit 85 passes through the optical system 87 to the screen ( (Not shown) to form a projected image. In this way, the projector 70 projects an image on the projection plane.
In step S5, the color configuration adjusting unit 73 determines whether an image is being projected on the projection plane. If the projection is in progress, the process proceeds to step S10.

In step S10, image analysis is performed. That is, the video analysis unit 72 reads frame data from the video memory 71, analyzes what luminance distribution and color component the projected video has, and determines whether the analysis result is monochrome display or color display. Is determined for each frame.
Next, in step S20, it is determined whether the image analysis is monochrome display. If the image analysis is monochrome display, the process proceeds to step S30. On the other hand, if the image analysis is not monochrome display, the process proceeds to step S40.

In step S30, since monochrome display is in progress, the color composition adjustment unit 73 does not need primary colors such as RGB, and therefore switches all segments of the cholesteric liquid crystal region to the focal conic state (or homeotropic state). Change to a mode that emphasizes brightness by increasing the amount of white light transmitted.
Here, the color composition adjusting unit 73 controls the ratio of the focal conic state or the homeotropic state by increasing the applied voltage as the color component of the display image decreases and approaches the monochrome component. In addition, when the display mode is luminance priority, the color configuration adjustment unit 73 controls the ratio of the focal conic state or the homeotropic state by increasing the applied voltage.
That is, the color configuration adjustment unit 73 selects whether each color component of the color wheel 60 is colored, transparent, or intermediate between them based on an instruction from the video analysis unit 72 or the mode selection unit 73, and the selection signal is the power supply unit 63. Output to. The power supply unit 63 generates an AC rectangular wave signal whose voltage is appropriately adjusted according to the selection signal input from the color configuration adjustment unit 73, and supplies power to the rotation shaft of the color wheel 60 from the power supply lines 64 a and 64 b. Power is supplied to the electrodes 65a and 65b. The color wheel 60 has a rotating shaft rotated by a rotation drive mechanism (not shown), and an AC rectangular wave signal fed from the supply electrodes 56a and 65b is applied to the transparent electrodes 61c and 61e.
As described above, the power supply unit 63 can generate the voltages applied to the cholesteric liquid crystal by classifying them into three groups of V _L and V _C, V _C and V _{H, and} V _L and V _H. The voltage configuration can be set in accordance with the mode for switching between (V _H ), focal conic state (V _C ), and planar state (V _L ). As a result, the ratio of emphasizing color reproducibility and brightness of the projected image can be finely set by the applied voltage.
Thereby, the ratio of the focal conic state or the homeotropic state of the cholesteric liquid crystal layer 61d sandwiched between the transparent electrodes 61c and 61e can be controlled by increasing the applied voltage.

On the other hand, since color display is being performed in step S40, the color composition adjustment unit 73 switches all the segments of the cholesteric liquid crystal region to the planar state to emphasize color reproducibility in order to use many colors as in animation and movies. Change to mode.
Here, the color configuration adjusting unit 73 performs control to increase the ratio of the planar state as the color component of the display image increases. In addition, the color configuration adjusting unit 73 performs control to increase the ratio of the planar state when the display mode is saturation priority.
That is, the color configuration adjustment unit 73 selects whether each color component of the color wheel 60 is colored, transparent, or intermediate between them based on an instruction from the video analysis unit 72 or the mode selection unit 73, and the selection signal is the power supply unit 63. Output to. The power supply unit 63 generates an AC rectangular wave signal whose voltage is appropriately adjusted according to the selection signal input from the color configuration adjustment unit 73, and supplies power to the rotation shaft of the color wheel 60 from the power supply lines 64 a and 64 b. Power is supplied to the electrodes 65a and 65b. The color wheel 60 has a rotating shaft rotated by a rotation drive mechanism (not shown), and an AC rectangular wave signal fed from the supply electrodes 56a and 65b is applied to the transparent electrodes 61c and 61e.
As a result, the applied voltage is increased, and the ratio of the planar state of the cholesteric liquid crystal layer 61d sandwiched between the transparent electrodes 61c and 61e is increased.

Next, in step S50, image projection is performed. If the color composition adjustment unit 73 is performing projection in step S55, the process returns to step S5 and continues the process. On the other hand, if the projection is not in progress, the process is terminated.
Thus, the transmittance can be changed by performing control to change the transmittance of the cholesteric liquid crystal based on the video information.
In this way, when the display mode is luminance priority, control is performed to increase the ratio of the focal conic state or homeotropic state, and when the display mode is saturation priority, control is performed to increase the ratio of the planar state. Depending on the display mode, there are two types of usage: emphasizing color reproducibility and brightness.
In this way, the applied voltage is adjusted and controlled so that the ratio of the focal conic state or homeotropic state increases as the color component of the display image decreases and approaches the monochrome component, and the planar state increases as the color component of the display image increases. By adjusting and controlling the applied voltage so as to increase the ratio, two types of usage can be performed: color reproducibility and brightness emphasis.
Inside the projector, the color wheel also rises in temperature due to the heat generated from the peripheral components. Therefore, it is preferable to use a material having high temperature resistance (for example, a polymer) for the cholesteric liquid crystal.

<Examples of Embodiments and Effects of the Present Invention>
<First aspect>
The color wheel of this aspect is a color wheel 20, 30, 40, 50 that includes a plurality of color regions arranged in the rotation direction and generates light of different color components by transmitting light to the individual color regions. The at least one color region includes a plurality of light-transmitting layers, and the at least one light-transmitting layer is a cholesteric liquid crystal 61d whose transmittance can be changed.
According to this aspect, at least one color region of the color wheel is composed of a plurality of light-transmitting layers, and the at least one light-transmitting layer is a cholesteric liquid crystal capable of changing the transmittance. The color configuration can be arbitrarily changed, and both brightness and color reproducibility can be achieved.
As a result, it is possible to realize a DLP projector that is more advantageous for image quality and miniaturization.
<Second aspect>
The cholesteric liquid crystal 61d of this embodiment includes a transparent electrode in two layers sandwiching the cholesteric liquid crystal, and changes the transmittance of the cholesteric liquid crystal by applying a voltage to the transparent electrode.
According to this aspect, the transmittance can be changed by applying a voltage to the transparent electrode in the two layers sandwiching the cholesteric liquid crystal.

<Third aspect>
In the cholesteric liquid crystal 61d of this embodiment, the arrangement of liquid crystal molecules forms a helical structure.
According to this aspect, a specific wavelength band is selectively reflected.
<4th aspect>
The cholesteric liquid crystal 61d of this embodiment has a structure in which a plurality of layers formed by the arrangement of liquid crystal molecules of cholesteric liquid crystal are stacked, and the wavelength of reflected light and the state of polarization are different in each layer.
According to this aspect, since the wavelength of reflected light and the state of polarization are different, higher saturation can be set.

<5th aspect>
The color region of the color wheel of this aspect is divided into at least two or more perpendicular to the rotation direction, and a planar state and a focal conic state are alternately assigned to each of the divided regions.
According to this aspect, by assigning a planar state and a focal conic state alternately to each divided area, two types of usage, emphasizing color reproducibility and brightness, can be performed.
<Sixth aspect>
The color wheel of this aspect is characterized in that the planar state or the focal conic state maintains the planar state or the focal conic state without applying a voltage.
According to this aspect, the planar state or the focal conic state can be maintained without applying a voltage.
<Seventh aspect>
The projector according to this aspect includes a color configuration adjustment unit 73 that changes the transmittance by controlling the voltage applied to the two transparent electrodes based on the video information.
According to this aspect, two types of usage can be performed: color reproducibility and brightness emphasis.

<Eighth aspect>
In the projector according to this aspect, the color configuration adjustment unit 73 performs control to increase the ratio of the focal conic state or the homeotropic state as the color component of the video information decreases and approaches the monochrome component, and the color component of the video information increases. Control is performed to increase the ratio of the planar state as the number of times increases.
According to this aspect, two types of usage, color reproducibility and brightness emphasis, can be performed according to the color components of the video information.
<Ninth aspect>
The projector according to this aspect has one of a luminance priority mode indicating that priority is given to the luminance adjustment of the projected video and a saturation priority mode indicating that priority is given to the saturation adjustment of the projected video as a display mode when necessary. A mode selection unit 74 that selectively inputs and a color configuration adjustment unit 73 that changes the transmittance by controlling the voltage applied to the two transparent electrodes based on the display mode are provided.
According to this aspect, two types of usage, color reproducibility and brightness emphasis, can be performed according to the display mode.
<10th aspect>
In the projector according to this aspect, the color configuration adjustment unit 73 performs control to increase the ratio of the focal conic state or the homeotropic state when the display mode is priority on luminance, and the planar state when the display mode is priority on saturation. Control is performed to increase the ratio.
According to this aspect, two types of usage, color reproducibility and brightness emphasis, can be performed according to the display mode.

  DESCRIPTION OF SYMBOLS 1 ... Upper layer substrate, 3 ... Lower layer substrate, 5 ... Cholesteric liquid crystal layer, 7 ... White light, 8 ... Light, 10 ... Cholesteric liquid crystal, 10a1 ... 1st layer, 10a2 ... 2nd layer, 20 ... Color wheel, 30 ... Color Wheel, 40 ... Color wheel, 50 ... Color wheel, 50g1 ... Segment, 62 ... Rotating shaft, 63 ... Power supply unit, 70 ... Projector, 71 ... Video memory, 72 ... Video analysis unit, 74 ... Mode selection unit, 73 ... Color Configuration adjustment unit, 81 ... light source, 85 ... DMD unit, 87 ... optical system

JP 2006-113276 A JP 2006-162658 A JP 2006-215431 A JP 2007-47700 A JP 2008-181032 A Japanese Patent Laid-Open No. 2001-305652 JP 2010-164645 A

Claims (10)

A color wheel having a plurality of color regions arranged in a rotation direction and generating light of different color components by transmitting light to each color region,
The color wheel according to claim 1, wherein the at least one color region includes a plurality of light-transmitting layers, and the at least one light-transmitting layer is a transmittance-changeable member capable of changing the transmittance. The transmittance changeable member is
A transparent electrode is provided in two layers sandwiching the transmissible member,
The color wheel according to claim 1, wherein the transmittance of the transmissible member is changed by applying a voltage to the transparent electrode. The transmittance changeable member is
3. The color wheel according to claim 1, wherein the alignment of the liquid crystal molecules comprises a cholesteric liquid crystal forming a spiral structure. The transmittance changeable member is
A structure in which a plurality of layers formed by alignment of liquid crystal molecules of the cholesteric liquid crystal is laminated,
The color wheel according to claim 3, wherein the wavelength and the polarization state of the reflected light are different in each of the layers. The color region is
5. The color wheel according to claim 3, wherein the color wheel is divided into at least two perpendicular to the rotation direction, and a planar state and a focal conic state are alternately allocated to each of the divided regions.   The color wheel according to claim 5, wherein the planar state or the focal conic state maintains the planar state or the focal conic state without applying the voltage. A color wheel according to any one of claims 1 to 6;
And a control unit configured to change the transmittance by controlling a voltage applied to the two layers of transparent electrodes based on video information. The control means includes
As the color component of the video information decreases and approaches the monochrome component, control is performed to increase the ratio of the focal conic state or the homeotropic state, and as the color component of the video information increases, the ratio of the planar state is increased. The projection apparatus according to claim 7, wherein control is performed. A color wheel according to any one of claims 1 to 6;
An input means for selectively inputting one of the luminance priority mode indicating priority of the luminance adjustment of the projected video and the saturation priority mode indicating priority of the saturation adjustment of the projected video as a display mode when necessary; ,
And a control unit configured to change the transmittance by controlling a voltage applied to the two layers of transparent electrodes based on the display mode. The control means includes
When the display mode is luminance priority, control is performed to increase the ratio of the focal conic state or the homeotropic state, and when the display mode is priority to saturation, control is performed to increase the ratio of the planar state. The projection apparatus according to claim 9.

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