JP2005266021A - Projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide color filters with the color ratio of the color filter being different, and cost reduction and miniaturization can be made. <P>SOLUTION: A color wheel 170 has color filters 200, 210, 220 and 230 of R (red), G (green), B (blue) and W (white) arrayed in the peripheral direction. The boundary 280 of the R filter and the W filter is regulated by a straight line from a position P1 offset from the center O of the color wheel toward the outer periphery. The boundaries 250, 260 and 270 of the other color filters are regulated by a straight line in a radial direction from the center O of the color wheel toward the outer periphery. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a projector using a spatial modulation device, and more particularly to a projector using a DMD (Digital Micro-mirror Device).

  A projector that displays a color image using a DMD or a liquid crystal device as a spatial modulation device has been put into practical use. A DLP (Digital Light Processing) type projector using DMD irradiates light onto a DMD made of a semiconductor element, and enlarges and projects the reflected light with a lens or the like to display a color image.

  A DLP projector is disclosed in, for example, Patent Document 1 by the present applicant. As shown in FIG. 8, the light from the white light source 51 is reflected by an elliptical mirror 52, and the reflected light is incident on a rotatable color wheel 53. The color wheel 53 is a transmissive filter in which R (red), G (green), and B (blue) color filters are arranged in the circumferential direction. The light transmitted through the color wheel is reflected by the condenser lens 1 and the spherical mirror 2 serving as a folding mirror, and enters the DMD 56 at a high angle. Of the light incident on the DMD, the light reflected by the on-state pixels is displayed on the screen 58 via the projection lens 57. R, G, and B light are sequentially transmitted from the color wheel 53, and the DMD pixel is driven at a timing synchronized therewith, so that a time-division color image is displayed.

  Patent Document 2 discloses a projector that improves the brightness of a display image by moving a color wheel in which such sequential color filters are arranged. By moving the color wheel, all of the beam from the illumination light source is transmitted through the color wheel or a part thereof. As shown in FIG. 9A, color filters of R, G, and B are arranged on the color wheel, and the color hole moves in a direction orthogonal to the rotation axis. As a result, the position of the incident beam on the color wheel is changed to A, B, and C, and the projection image in the color mode or the monochrome mode (or gray scale) can be displayed. In particular, when priority is given to luminance, display in the monochrome mode is realized. In addition, as shown in FIG. 9B, by adding an array pattern of color filters having different R ′, G ′, and B ′ to the outermost periphery of the color wheel and changing the color ratio thereof, various colors can be obtained. The balance and white point can be selected.

  Further, Patent Document 3 discloses a projector that uses a color wheel having two color rings with different color ratios as shown in FIG. 9B and can automatically switch the color ring to be used. . That is, it is determined whether the image signal input to the projector is an RGB input signal or a video input, and the coloring to be used is switched according to the determination result.

Patent 3121843 JP-A-9-163391 JP 2003-167297 A

  However, the conventional projector has the following problems. In the color wheel used in the projector, as shown in FIG. 9A, the boundaries of the R, G, B color filters are defined by straight lines in the radial direction of the color wheel. That is, if the incident position of the beam is within the radius of the color wheel, the color ratios of R, G, and B are constant, and the color ratio cannot be varied within the color wheel. For this reason, in order to change the color ratio, it is necessary to largely move the color wheel to the beam incident position B or C.

  On the other hand, as shown in FIG. 9B, it is possible to add coloring with different color ratios to the color wheel, but creating such a color wheel is a factor of high cost. In general, when forming a color filter, vapor deposition or sputtering is performed on a glass substrate, but a mask process corresponding to the number of filters is required. For example, in the case of R, G, B color filters, the mask process is required three times. For this reason, when two filters having different color ratios are formed on a single color wheel, the number of manufacturing steps increases and the cost of the color wheel also increases. Furthermore, by adding a color ring in the radial direction, the diameter of the color wheel is increased and the weight of the color wheel is increased. Then, it becomes difficult to adjust the balance of the color wheel, and it is difficult to reduce the size of the motor that drives the color wheel.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a color filter that can be reduced in cost and size that is different in color ratio of the color filter.
Furthermore, the present invention provides an illumination optical system and an image display device that can change the color display level by using such a color filter.

  The color wheel according to the present invention is used in an image display device using a spatial modulation element and has the following configuration. The color wheel has a rotatable disk shape, and a plurality of color filters are arranged in the circumferential direction. The boundary between at least two color filters selected from the plurality of color filters is offset from the center of the color wheel. The boundary between at least two color filters selected from among the plurality of color filters is defined by a radial straight line from the center of the color wheel toward the outer periphery.

  Preferably, the plurality of color filters include filters that transmit R (red), G (green), and B (blue) components, and at least one boundary of the R color filter is defined by an offset line. Thereby, the area of the R color filter is increased, that is, the ratio of the transmitted red component light is increased, and a projected image having color rendering properties can be displayed. Also, by defining at least one boundary of the W color filter with an offset line, the area of the W color filter can be increased, and as a result, a high-luminance or bright image can be displayed. Thus, by defining the boundary of the color filter by the offset line, the color ratio of the color wheel can be easily varied toward the outer periphery.

  Preferably, the offset line may be a straight line or a curved line. The curve may be an involute curve, for example. In addition, when a concentric circle is drawn with the center of the color wheel, it is desirable that one end of the boundary of each color filter is located on the concentric circle. In this case, the position offset from the center is located on a concentric circle.

  An illumination optical device (illumination optical system) according to the present invention includes a color wheel having the above characteristics, a light source, a rotating unit that rotates the color wheel, and a color wheel that moves in a direction perpendicular to the rotation axis. Moving means for positioning the color wheel on the optical path. Preferably, a light tunnel or a light integrator is disposed between the light source and the color wheel. Further, a light tunnel or an optical integrator may be disposed on the emission side of the color wheel. The moving means can be configured by a gear, a belt mechanism, a direct drive by a motor, or the like.

  An image display apparatus according to the present invention includes an illumination optical system having the above characteristics, a modulation unit that modulates light from the illumination optical system, and a projection unit that projects the modulated light. Preferably, the image display device has an input unit so that the position of the color wheel can be selected in response to an input from the input unit. For example, when a user selects a display mode (a display mode with high luminance or a display mode with high color rendering), the color wheel is moved so that a color ratio corresponding to the selection is selected. The image display device is, for example, a front projection or rear projection projector. The modulation means is preferably a DMD, but is not limited to this, and may be a liquid crystal device.

  According to the color wheel of the present invention, it is possible to easily change the color ratio simply by adjusting the boundary of the color filter by combining the boundary of the color filter in the radial direction and the boundary of the color filter in the radial direction. The manufacturing process is not increased as in the prior art. Therefore, a low-cost color wheel can be provided, and further, the color wheel can be reduced in size and weight. In addition, by using such a color wheel for an illumination optical system and a projector, it is possible to display a color image suitable for the user's preference.

  The color wheel according to the present invention is preferably used in an illumination optical system of a DLP front projection projector. Hereinafter, it will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing an internal configuration of a projector according to an embodiment of the invention. The projector 100 processes an analog image input signal or a digital image input signal 102 to generate RGB digital image data having a format plane corresponding to the number of DMD pixels, and a digital image from the preprocessing unit 110. A control unit 120 that controls driving of the DMD 150 based on the data, a lamp driving circuit 130 that controls driving of the discharge lamp 160, and a color wheel driving unit that controls rotation of the color wheel and movement in a direction perpendicular to the rotation axis thereof. 140, DMD 150, an optical system 180 that irradiates the DMD 150 with light from the color wheel 170, a projection optical system 182 that enlarges reflected light from the DMD 150 and displays it on the screen, and detects the position of the color wheel 170. Sensor that supplies detection result to control unit 120 Configured to include a 190.

  The lamp driving circuit 130 controls activation of the discharge lamp 160 as a light source and AC driving of the discharge lamp after activation. The color wheel driving unit 140 includes a moving mechanism that controls the rotation of the stepping motor connected to the color wheel 170 and moves the color wheel 170 and the motor in a direction perpendicular to the rotation axis. The beam from the discharge lamp 160 is incident on the color wheel substantially perpendicularly, and R, G, B (or W) light is sequentially transmitted and emitted as the color wheel 170 rotates. The DMD 150 includes a plurality of arrayed mirror elements corresponding to sizes such as VGA and XGA, and each mirror element varies its angle in response to digital image data.

  FIG. 2 shows a plan view of the color wheel of this embodiment. The color wheel 170 includes R (red), G (green), B (blue), and W (white or transparent) color filters 200, 210, 220, and 230 in the circumferential direction thereof. A shaft hole 240 connected to the motor rotor is formed in the center. When the center or rotation axis of the color wheel is O, the area of each color filter is a range from the concentric circle Q1 of the center O to the outer periphery Q2.

  A boundary 250 between the R filter 200 and the G filter 210 is a straight line in the radial direction from the center O toward the outer periphery, that is, a line segment between intersections A1 and A2 of the concentric circle Q1 and the outer periphery Q2. A boundary 260 between the G filter 210 and the B filter 220 is also defined by the same straight line at the intersection points B1 and B2, and a boundary 270 between the B filter 220 and the W filter 230 is also defined by the same straight line at the intersection points C1 and C2. However, the boundary 280 between the R filter 200 and the W filter 230 is defined by offset lines P1 and P2 having an inclination angle θ from the straight lines P1 and P0 in the radial direction.

  The G filter 210 and the B filter 220 have a sector shape with an inner angle of 90 degrees with respect to the center O, while the R filter 200 has an area increased by the inclination of the boundary 280 and substantially corresponds to a sector shape having an inner angle larger than 90 degrees. . On the other hand, the W filter 230 has a reduced area and corresponds to a sector having an inner angle substantially smaller than 90 degrees. For this reason, when the color wheel 170 is rotated, the color ratio is varied depending on the position of the beam incident on the color wheel 170. For example, when the beam is incident at a position S1 close to the center O, the color wheel 170 transmits R, G, B, and W light that is divided into four substantially evenly, but is positioned away from the center O. When the beam is incident on S2, the ratio of the R light increases from the color wheel 170, and the ratio of the W light decreases. Thus, the color ratios of R, G, B, and W can be changed linearly from the center toward the outer periphery.

  FIG. 3 is a diagram showing a color wheel according to the second embodiment. In the color wheel 172 of the second embodiment, the boundary 252 between the W filter 230 and the G filter 210 is defined by a straight line in the radial direction, but the boundary 262 between the G filter 210 and the B filter 220, and the B filter 220 and R The boundary 272 of the filter 200 and the boundary 282 of the R filter 200 and the W filter 230 are defined by an offset line shifted from the radial direction. Assuming that the inclination angle formed by the boundary 262 with the straight lines B0 and B1 is θ1, the inclination angle formed by the boundary 272 with the straight lines C0 and C1 is θ2, and the inclination angle formed by the boundary 282 with the straight lines P0 and P1 is θ3, θ1 <θ2 < The relationship is θ3. Preferably, θ1 = 1/3 × θ3 and θ1 = 2/3 × θ3.

  When this color wheel 172 is used, the ratio of W (white) can be varied while the ratios of R, G, and B are substantially constant. That is, when the beam is incident on the position S2 far from the center as compared with the beam at the position S1 close to the center, the projected image can be brightened by the increase in the area of the W filter 230.

  In the first and second embodiments, the boundary of the filter is defined by the inclination angle θ, but instead may be defined by the arc length. For example, the boundary 282 between the W filter 230 and the R filter 200 has arc lengths P0 and P2 (P0 is the intersection of the radius passing through P1 and the outer periphery), the boundary 272 is the arc length C2, C0, and the boundary 262 is the arc length B2 and B0. Can be defined by

  FIG. 4 is a view showing a color wheel according to a third embodiment of the present invention. The color wheel 174 of this embodiment differs from the first and second embodiments in that the boundary is defined by a straight line, whereas the boundary is defined by a curve. That is, the boundary 264 between the G filter 210 and the B filter 220, the boundary 274 between the B filter 220 and the R filter 200, and the boundary 284 between the R filter 200 and the W filter 230 are defined by the curves. For each boundary 264, 274, 284, for example, an involute line can be used. A desired color ratio change can be obtained by adjusting the arc length (B0B2, C0C2, P0P2) of each filter.

  As described above, according to each of the above-described embodiments, it is possible to provide a color wheel that can change the color ratio without any step by making at least one of the color filter boundaries different from a straight line in the radial direction. Can do. Further, as in the prior art, a color filter is added to the outer periphery, and the cost can be reduced without increasing the manufacturing process of the filter.

  In each of the above embodiments, R, G, B, and W are used as the color filters, but other combinations may be used. For example, R, G, and B color filters may be used. Furthermore, the color ratio by each filter can be appropriately changed according to design matters. In addition, the color filter can be manufactured by forming a thin film on a glass substrate by vapor deposition or sputtering, but besides this, glass having a color filter function is processed into a size according to the color ratio, A color wheel can be manufactured by bonding the side surfaces of glass with an adhesive or the like.

  Next, an example in which the color wheel described in the above embodiments is applied to an illumination optical system is shown in FIG. As shown in FIG. 5A, the lamp 160 includes a discharge lamp 162 and a reflector 164, and the light collected by the reflector 164 is incident on the light tunnel 166 (or an optical integrator). The incident light bundle is emitted as a light bundle having a substantially uniform illuminance in the light tunnel 166 and is incident on the color wheel 170 substantially perpendicularly. The color wheel 170 is rotated by a motor 178 and moved in a direction Y orthogonal to the rotation axis by a color wheel driving unit 140 (see FIG. 1). By changing the position of the color wheel 170, the incident position of the beam from the lamp 160 is changed, and thereby the color ratio of the transmitted light can be varied. If the color wheel 170 of the first embodiment is used, if the incident position of the beam on the color wheel 170 is linearly varied from the center O toward P0, the red ratio is linearly increased accordingly. be able to. The color wheel 170 may be adjusted to a desired position while viewing the color rendering properties of the projected image.

  The illumination optical system of FIG. 5B has a configuration in which the light beam from the lamp 160 is directly incident on the color wheel 170 and the transmitted light is incident on the light tunnel 166 (or light integrator). Further, the color wheel 170 may be moved in the axial direction X.

  FIG. 6 is a diagram showing a configuration of an optical system of a projector using the illumination optical system shown in FIG. The light from the lamp 160 is reflected by the reflector 164 and enters the light tunnel 166. Light from the light tunnel 166 is split into R, G, B, (or W) by the color wheel 170. The light transmitted through the color wheel 170 illuminates the DMD 150 via the condenser lens 182, the first mirror 184, and the second mirror 186. The light modulated by each pixel of the DMD 150 is magnified by the projection lens 190 and projected on the screen.

  The movement of the color wheel 170 in the Y direction is performed by the color wheel driving unit 140, and the movement method is realized using a known technique. For example, a gear mechanism or a belt mechanism for converting the rotation of the motor into a linear motion can be used. The control unit 120 may monitor the detection result from the sensor 190 and stop the color wheel at a predetermined position. For example, when the user gives an instruction to select a display mode, the color wheel driving unit 140 can be controlled to respond to the instruction. When the user selects a high-luminance display mode, the color wheel is positioned so that the ratio of the W filter is high. Alternatively, when a display mode having color rendering properties is selected, the color wheel is positioned so that the ratio of the R filter is increased.

  Further, the color wheel 170 may be moved by a manual operation switch as shown in FIG. The knob 300 of the operation switch is protruded from the housing 302 of the projector, and the knob 300 is slid. At this time, the horizontal hole 306 formed in the support portion 304 is guided by the guide pin 308 and is slid from the state of FIG. 7A to the state of FIG. 7B and fixed to the support portion 304. (Color wheel and motor) 170a may be moved.

  When the color wheel is positioned as described above, a plurality of types of micromirrors stored in a memory (not shown) installed in the controller 120 in advance according to the angle ratio of the color filter corresponding to the position. An optimum pulse sequence is selected from the drive pulse sequence.

  Although the preferred embodiment of the present invention has been described in detail, the present invention is not limited to the specific embodiment, and various modifications, within the scope of the gist of the present invention described in the claims, It can be changed.

  The color wheel according to the present invention can be used in an image display device such as a projector using a spatial modulation device.

It is a block diagram which shows the internal structure of the projector of this invention. It is a top view which shows the color wheel which concerns on the 1st Example of this invention. It is a top view which shows the color wheel which concerns on the 2nd Example of this invention. It is a top view which shows the color wheel which concerns on the 3rd Example of this invention. It is the figure which applied the color wheel to the illumination optical system. It is a figure which shows the optical system of the projector using the illumination optical system of FIG. It is a figure explaining the example of a movement of a color wheel. It is a figure which shows the structure of the conventional projector. It is a figure which shows the structure of the conventional color wheel.

Explanation of symbols

100: projector 110: preprocessing unit 120: control unit 130: lamp driving circuit 140: color wheel driving unit 150: DMD
160: Lamps 170, 172, 174: Color wheel

Claims (13)

A color wheel used in an image display device using a spatial modulation element,
The color wheel has a rotatable disk shape, and a plurality of color filters are arranged in the circumferential direction thereof.
The boundary between at least two types of color filters selected from the plurality of color filters is defined by an offset line from the position offset from the center of the color wheel to the outer periphery,
A color wheel, wherein a boundary between at least two color filters selected from the plurality of color filters is defined by a radial straight line from the center of the color wheel toward the outer periphery. The plurality of color filters include filters that transmit R (red), G (green), and B (blue) components, and a boundary of at least one of the R color filters is defined by the offset line. The color wheel described in. The color wheel according to claim 1, wherein the plurality of color filters further include a filter that transmits white component light, and a boundary of at least one of the W color filters is defined by the offset line. The color wheel according to any one of claims 1 to 3, wherein the offset line is a straight line inclined at a constant angle with a straight line in a radial direction. The color wheel according to claim 1, wherein the offset line includes a curve. The color wheel according to claim 1, wherein the color ratio of the color wheel changes from the center toward the outer periphery. A color wheel according to any one of claims 1 to 6;
A light source;
A rotating means for rotating the color wheel;
An illumination optical apparatus comprising: a moving unit that moves the color wheel in a direction orthogonal to the rotation axis and positions the color wheel on an optical path from the light source. The illumination optical apparatus according to claim 7, wherein a light tunnel or an optical integrator is disposed between the light source and the color wheel. The illumination optical apparatus according to claim 7, wherein a light tunnel or an optical integrator is disposed on the emission side of the color wheel. An illumination optical apparatus according to any one of claims 7 to 9,
Modulation means for modulating light from the illumination optical system;
Projection means for projecting modulated light;
An image display apparatus. The image display device according to claim 10, further comprising an input unit, wherein the moving unit moves the color wheel in response to an input from the input unit. The image display apparatus according to claim 11, wherein the input unit includes an instruction for a display mode of a display image. The image display apparatus according to claim 10, wherein the modulation unit includes a DMD.

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