JP2004226545A - Color wheel, and illumination optical system and projector using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color wheel of low cost, to provide an illumination optical system and a projector using such a low cost color wheel, to provide the projector which can display a full color display and a monochrome display selectively using the low cost color wheel, and to provide the color wheel which can raise white luminance and the projector using the color wheel. <P>SOLUTION: The color wheel has an annular supporting member 20 in which an opening 21 is formed at its center part and filter members 32, 34, 36 which are arranged in the peripheral part of the annular supporting member 20. Each of the filter members 32, 34, 36 includes a front surface 40, a rear face, and an end face 48 which extends in the radial direction with respect to the center axis of the supporting member 20. At least a part of the rear face 42 is fixed to the member 20 and the end face 48 of the filter member is joined to end face of other filter member. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a color wheel used in an image forming apparatus such as a projector, and more particularly, to a DLP (Digital Light Processing) using a spatial light modulator such as a DMD (Digital Mirror Device): DLP is a registered trademark of Texas Instruments. The present invention relates to a system-type projector.
[0002]
[Prior art]
The DLP type projector irradiates a DMD made of a semiconductor mirror element with light, enlarges the modulated light by a projection lens, and displays a color image on a screen. As shown in FIG. 1 of Patent Document 1 previously filed by the present applicant, white light from a light source is reflected by an elliptical mirror 52, and the reflected light is in a disk shape in which R / G / B color filters are arranged. Are sequentially changed to RGB colors by the color holes 53, and the DMD 56 is irradiated. The DMD 56 is time-divisionally driven in synchronization with the color wheel 53, modulates the emitted light according to image data, and the light is displayed on a screen 58 via a projection lens 57.
[0003]
The color wheel used in the DLP system has R / G / B color filters arranged on the outer periphery thereof, and the light incident on the color wheel is transmitted therethrough to correspond to the R, G, B filters. The light is emitted as monochromatic light. The color wheel is manufactured, for example, by depositing substances constituting R, G, and B filters on a glass substrate by vapor deposition, sputtering, or the like, as shown in Patent Document 2. During deposition of the R filter, regions of the G, B filters are masked, and during deposition of the G filter, regions of the R, B filters are masked, and during deposition of the B filter, R, , G are masked. Thus, the mask process is performed a number of times corresponding to the number of filters, and each filter is deposited on the glass substrate.
[0004]
[Patent Document 1]
Patent No. 3,121,843 [Patent Document 2]
JP-A-6-347639
[Problems to be solved by the invention]
However, the above-described conventional color wheel has the following problems. The color wheel disclosed in Patent Document 2 has an advantage of not using a frame or a spoke, but has a mask corresponding to the number of filters (for example, three times in the case of R, G, and B color filters) during vapor deposition or sputtering. Requires a process. Therefore, the number of manufacturing steps increases, and the cost of the color wheel also increases. Further, when displaying white light using a color wheel in which R, G, and B color filters are arranged, boundaries of the R, G, and B color filters are used. For each rotation of the color wheel, R + G, G + B, and B + R are turbid at the boundary of RGB, but when viewed over one rotation, R + G + G + B + B + R = 2RGB, and this boundary period can be used as white. . However, white display by such a method sometimes does not have sufficient luminance.
[0006]
Therefore, an object of the present invention is to solve the above-mentioned conventional problems and to provide a low-cost color wheel.
Another object of the present invention is to provide an illumination optical system and a projector using such a low-cost color wheel.
Still another object of the present invention is to provide a projector capable of selectively displaying full-color display and black-and-white display using a low-cost color wheel.
Still another object of the present invention is to provide a color wheel capable of improving white luminance and a projector using the same.
[0007]
[Means for Solving the Problems]
A color wheel according to the present invention includes an annular support member having an opening formed in the center, and at least two filter members arranged on an outer peripheral portion of the annular support member. Each is a first main surface, a second main surface facing the first main surface, and a radial direction between the first and second main surfaces and with respect to a center axis of the support member. And at least a part of the second main surface is fixed to the support member, and an end surface of the filter member is joined to an end surface of another filter member. By connecting a plurality of color filter members to each other and fixing them on the support member, the number of manufacturing steps can be simplified and a low-cost color wheel can be obtained.
[0008]
Preferably, the support member includes a step formed in a circumferential direction, and a second main surface of the filter member is positioned at the step. By using the step portion of the support member, the positioning of the filter member is facilitated, the contact area between the filter member and the support member is increased, and the coupling strength between the two can be increased.
[0009]
The at least two filter members preferably include a glass member having a predetermined thickness, and an end surface of the filter member includes a cut surface of the glass member. As the glass member, high light transmittance, heat-resistant glass can be used, glass corresponding to each filter member is prepared in advance, and a filter member of a predetermined shape is cut out therefrom, and the cut glass member Are bonded or adhered to each other. By doing so, a filter member having a uniform thickness and a desired size can be combined, and it is necessary to perform a mask process for vapor deposition or sputtering when forming a filter on a glass substrate as in the related art. There is no. Further, the filter member may further include a coating layer on the glass member. In this case, a color filter for transmitting, for example, R, G, and B is coated on each glass, and the respective filter members are cut out from this, and the cut out filter members are joined to each other. You may make it do. Preferably, an end face of the filter member is joined to an end face of another filter member via an adhesive.
[0010]
The at least two filter members include a filter member for transmitting light of substantially R, G, and B wavelengths. Further, a filter member that transmits light of other wavelengths may be provided, and for example, a filter member that substantially transmits white light can be included.
[0011]
More preferably, a cutout is formed in at least one of the at least two filter members, and the cutout forms a cavity when the at least two filter members are joined. Good. The notches are arranged at substantially equal intervals in the circumferential direction of the color wheel. The notch can be used when the projector is in the black and white display mode.
[0012]
The illumination optical system according to the present invention includes the above-described color wheel, a rotation unit coupled to the support member of the color wheel, the rotation unit rotating the color wheel, and a light source, and irradiates the color wheel with light from the light source. The light selected by the filter member of the color wheel is transmitted, and illumination is performed using the transmitted light. By using a low-cost color wheel, a low-cost illumination optical system can be provided.
[0013]
The projector according to the present invention includes the above-described color wheel, a rotation unit coupled to the support member of the color wheel and rotating the color wheel, a light source, a light modulation unit, and a light modulated by the light modulation unit. Projecting means for projecting light, irradiating the light from the light source to the color wheel, and irradiating the light selected by a filter member of the color wheel to the light modulating means. By using a low-cost color wheel, a low-cost projector can be provided.
[0014]
Preferably, the light modulation means includes a DMD. Alternatively, it may be a liquid crystal device. Further, the projector may include a position changing unit that changes a position of the color wheel, and may allow light from the light source to enter a cavity formed by the cutout portion of the color wheel. By allowing white light from the light source to pass through the cutout portion, black and white display can be performed. In the case of monochrome display, there is no light loss due to the color wheel, and it is possible to provide a significantly brighter projected image.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described. FIG. 1A is a plan view illustrating a configuration of a color wheel according to the first embodiment, and FIG. 1B is a cross-sectional view taken along line X1-X1. The color wheel 10 includes a support member 20 and three filter members 32, 34, and 36 attached to the outer periphery of the support member 20. The support member 20 is an annular member having a diameter d1 and an opening 21 having a diameter d2 formed at the center thereof, and is made of, for example, a metal such as aluminum or iron. Alternatively, other than this, a glass member or a plastic member can be used. A motor rotor (not shown) is connected to the opening 21 of the support member 20. When the motor is driven to rotate, the color wheel 10 is rotated around the central axis of the support member 20.
[0016]
Color filter members 32, 34, 36 are attached to the outer peripheral portion of the surface 22 of the support member 20. In this example, the filter member 32 mainly selects light of a red (R) component wavelength, the filter member 34 mainly selects light of a green (G) component wavelength, and the filter member 36 mainly selects blue ( B) Select light of component wavelength. The filter members 32, 34, 36 are made of, for example, glass. Glass generally has a high light transmittance, so that loss of light absorption can be reduced. In addition, since heat resistance is high, a diameter of light incident on a color wheel can be reduced. By appropriately selecting a substance contained in the glass, a filter function corresponding to transmitted light can be provided.
[0017]
Each of the filter members 32, 34, and 36 is cut into a predetermined shape from glass having a fixed thickness (the thickness is 1 mm in this example). The color wheel 10 shown in FIG. 1 includes filter members 32, 34, and 36 having the same shape and having an inner angle of 120 degrees with respect to the central axis of the support member 20. The filter members 32, 34, and 36 have a front surface 40, a back surface 42, an inner peripheral surface 44 and an outer peripheral surface 46 concentric with the opening 21 of the support member 20, and extend in the radial direction from the central axis of the opening 21. An end surface 48 is provided between the outer peripheral surface 46 and the outer peripheral surface 46.
[0018]
Both end surfaces 48 of the filter member 32 are respectively joined to end surfaces 48 of the filter members 34 and 36, and the end surfaces 48 of the filter members 34 and 36 are respectively joined to form one plate-shaped filter. Then, a part of the back surface 42 of each filter member is attached to the front surface 22 of the support member 20 with an adhesive or the like so that the inner peripheral surfaces 44 of these filter members 32, 34, 36 are arranged concentrically with the opening 21. Fixed. At this time, the diameter of the filter members 32, 34, 36 is d3 (d3> d1), and the inner diameter of the inner peripheral surface 44 is d4 (d4> d2). d1, d2, d3, and d4 are preferably 20 mm, 10 mm, 42 mm, and 10 to 15 mm, respectively. These values are appropriately selected according to the design. In order to increase the bonding area between the back surface 42 of the filter members 32, 34 and 36 and the front surface 22 of the support member 20 and increase the bonding strength between them, the values of d2 and d4 may be equalized.
[0019]
According to the present embodiment, a filter member cut out of glass into a predetermined shape is joined to and fixed to the outer peripheral portion of the support member 20, so that a mask process is not required as in the related art. The number of manufacturing steps can be simplified, and the cost of the color wheel can be reduced.
[0020]
Next, a second embodiment of the present invention will be described. FIG. 2A is a plan view of a color wheel according to a second embodiment, and FIG. 2B is a cross-sectional view taken along line X2-X2. The color wheel 11 according to the second embodiment differs from the color wheel 10 according to the first embodiment in the configuration of the support members, and the other configurations are the same. The support member 50 has an opening 51 formed at the center thereof and a step 52 formed at the outer periphery thereof. The step portion 52 has a step surface 54 having a predetermined height lower than the surface 53, and the step surface 54 is formed concentrically with the opening 51 to have a constant width. The filter members 32, 34, and 36 are bonded by using the steps or corners of the step portion 52. By providing the step 52, the inner peripheral surface 44 of the filter members 32, 34, 36 is appropriately positioned on the support member 50, and further, the bonding area between the support member 50 and each of the filter members 32, 34, 36 is reduced. Since it becomes large, the joining strength can be increased. By doing so, even when the color wheel 11 is rotated at a high speed, it can withstand the strength thereof.
[0021]
Next, a third embodiment of the present invention will be described. FIG. 3A is a plan view of a color wheel according to the third embodiment, and FIG. 3B is a plan view showing a configuration of a filter member. The color wheel 12 according to the present embodiment has a plurality of notches 61, 62, 63 in the circumferential direction. For example, when the notch 61 is formed, as shown in FIG. 3B, the outer peripheral portions 61a and 63a are cut from both end surfaces of the filter member 36 (hatched regions in the drawing). Similarly, the other filter members 32 and 34 are cut at one part. Then, when the end faces 48 of the respective filter members are joined, cutouts 61, 62, 63 are formed on the joint surfaces, and the cutouts become hollow areas. The notches 61, 62 and 63 allow the light radiated therethrough to pass through. That is, since the white light from the lamp as the light source is transmitted as it is, it can be regarded as a white (W) color filter. By positively forming a white filter region on the color wheel 12, white luminance can be improved. Further, the color wheel 12 including such cutouts 61, 62, 63 can also be used when displaying a black-and-white mode image on a projector, as described later. In addition, it is desirable that the notches are formed at equal intervals on the color wheel. This is because, when the color wheel is rotated, by maintaining the weight balance of the color wheel evenly, aerodynamic characteristics can be maintained and noise can be reduced. However, the notches do not necessarily have to be at equal intervals in the circumferential direction, and the number and size of the notches can be changed as appropriate according to the design items required for the projector. Furthermore, when the notches are not arranged at equal intervals in the circumferential direction, or when the sizes of the notches are different, a weight may be added to maintain the balance of the color wheel. . For the weight, a metal or other plastic member can be attached with an adhesive.
[0022]
Next, a fourth embodiment of the present invention will be described. FIG. 4 is a plan view of a color wheel according to the fourth embodiment. The color wheel 13 according to the fourth embodiment includes a W (white) color filter member 78 between the filter members 72 and 76, in addition to the R, G, and B color filter members 72, 74, and 76. . The filter member 78 is cut out of glass that transmits white light. Since the white light can be transmitted for a period corresponding to the filter member 78 every time the color wheel 13 rotates once, the brightness of the white light can be further improved as compared with the conventional color wheel. Further, the color wheel 13 includes one notch 80 in a region continuous with the filter member 78.
[0023]
Next, a fifth embodiment of the present invention will be described. FIG. 5 is a cross-sectional view of the color wheel according to the fifth embodiment, which corresponds to a cross-sectional view taken along line X1-X1 of FIG. In the color wheel 14 according to the fifth embodiment, the filter members 92, 94, and 96 include a coating layer 98 on the surface. In addition to using glass itself as a filter member, a glass member having a coating layer formed thereon as a filter is prepared, and R, G, and B filter members are cut out therefrom. ) Laminate on top.
[0024]
Next, a projector having an illumination optical system to which the color wheel according to the present invention is applied will be described. FIG. 6 is a block diagram showing a main configuration of a DLP type projector according to the present invention. The projector 100 receives the image signal 111 and converts it into RGB digital image data having the same number of pixels as the DMD. The projector 100 controls the driving of the DMD 150 based on the digital image data from the preprocessing unit 110 and performs a lamp driving circuit. And a control unit 120 for controlling the color wheel driving unit 140 and the like. The lamp drive circuit 130 controls activation of the discharge lamp 160 as a light source and AC driving of the discharge lamp after the activation. The color wheel driving unit 140 rotates the color wheel 12 (here, the color wheel according to the third embodiment shown in FIG. 3 is used) to convert the light from the discharge lamp 160 into RGB, and further, A moving mechanism for moving the color wheel 12 in a direction perpendicular to the rotation axis is included. The position detection sensor 180 detects the position of the color wheel 12 and outputs a detection result to the control unit 120. The DMD 150 is irradiated via the optical system 190 with light sequentially converted into RGB from the color wheel 12 and modulates the light. The projection optical system 200 enlarges and projects the reflected light from the DMD 150 to display an image on a screen.
[0025]
FIG. 7 shows details of the optical system of FIG. The discharge lamp 160 as a light source is integrally attached to the spheroid mirror 161, and for example, a xenon arc short lamp, a metal halide lamp, an ultra-high pressure mercury lamp, or the like is used.
[0026]
The light tunnel 162 is a light transmission medium having a fixed length and a rectangular cross section, and emits light having a uniform light intensity distribution. The convergent light beam reflected by the elliptical mirror 161 is incident from the entrance of the light tunnel 162 at a predetermined angle of incidence, and the incident light is multiple-reflected on the inner wall of the light tunnel having a high refractive index to form a uniform light beam bundle. Is emitted. The emission aperture of the light beam emitted from the light tunnel 162 has a ratio of the long side to the short side of 4: 3 (or 16: 9).
[0027]
The color wheel 12 is rotated at a constant speed by the color wheel driving unit 140, and is arranged in a positional relationship such that light emitted from the light tunnel 162 is incident almost perpendicularly. The light incident on each of the filter members 32, 34, 36 of the color wheel 12 is sequentially converted (or separated) into light having R, G, B wavelengths. The optical system 190 includes a condenser lens 191 and a pair of reflecting mirrors 192, and the R, G, and B lights transmitted through the color wheel 12 are converted into parallel rays by the condenser lens 191 to irradiate the DMD 150. The DMD 150 is driven at a timing synchronized with the rotation of the color wheel 12, that is, the conversion into R, G, and B, and the mirrors constituting each pixel reflect R, G, and B light based on the RGB digital image data. . The R, G, and B lights reflected on by the DMD 150 are enlarged and projected by the projection optical system 200, thereby forming an image on the screen.
[0028]
The color wheel 12 is rotated by the color wheel driving unit 140 and is movable in a direction V perpendicular to the rotation axis, and the movement maintains a substantially vertical relationship with the light tunnel 162. As a result, light emitted from the light tunnel 162 is relatively moved in the radial direction of the color wheel 12. In the full color display mode, the color wheel 12 is positioned at a position where the light emitted from the light tunnel 162 sequentially irradiates the filter members 32, 34, 36 (hereinafter, the color mode position). Is stopped, and the light emitted from the light tunnel 162 is positioned at a position where the light emitted from the light tunnel 162 irradiates any of the cutouts 61, 62, and 63 (hereinafter, a black-and-white mode position). The light enters the condenser lens 191. This makes it impossible to display a color image, but instead, a particularly bright black-and-white image can be projected without light loss due to the color wheel. Such a black-and-white display mode is advantageous when displaying text and the like, for example, in which importance is placed on brightness rather than color.
[0029]
The position detection sensor 180 detects the position of the color wheel 12 and sends the detection result to the control unit 20. As described above, the control unit 120 controls the DMD 150 at a timing synchronized with the position of the color wheel 12 according to the position of the color wheel 12. Further, the control unit 120 controls the color wheel driving unit 140 based on the position detection result from the position detection sensor 180 to move the color wheel 12 to the selected position (color mode position or black and white mode position).
[0030]
The color wheel driving section 140 includes a stepping motor for rotating the color wheel 12, and further includes a moving mechanism for moving the color wheel 12 in the vertical direction V. As a driving source for horizontal movement, a linear motor or the like may be used, or it may be moved manually.
[0031]
In the example of the projector described above, the example using the color wheel 12 shown in FIG. 3 is shown. However, other color wheels according to the first to fifth embodiments may be applied to the illumination optical system of the projector. it can. When the color wheel 13 shown in FIG. 4 is used, white light may be displayed using the period of the filter portion (W) 78 (spoke time period).
[0032]
Further, in the above embodiment, the transmission type color wheel has been described, but the invention can be applied to a reflection type color wheel. FIG. 8 shows a color wheel according to the sixth embodiment. The color wheel 300 includes a filter member 302 that reflects a wavelength in the R band, a filter member 304 that reflects a wavelength in the G band, and a filter member 306 that reflects a wavelength in the B band. These filter members 302, 304, and 306 are made of glass, and their cut surfaces are adhered with an adhesive, and these filter members are combined together to form a columnar color wheel. An opening 311 is formed at the center of the color wheel 300 to connect a rotor of a motor for rotating and driving the color wheel. When the color wheel 300 is rotated and light is applied to the reflective surface 310 on the outer periphery thereof, R, G, and B reflected lights are sequentially reflected from the reflective surface 310, and the reflected light is used for an illumination optical system. be able to.
[0033]
Further, the color wheel 310 can include a color filter 312 including a white filter member 308. The white filter member 308 is joined between the filter members 302 and 304. By irradiating the outer peripheral surface of the color filter 312 with light, reflected light of R, G, B, and W can be reflected. Thereby, the luminance of white can be improved.
[0034]
As described above, the preferred embodiments of the present invention have been described in detail, but the present invention is not limited to such specific embodiments, and within the scope of the present invention described in the claims, Various modifications and changes are possible.
[0035]
【The invention's effect】
According to the present invention, at least two filter members are arranged on the outer peripheral portion of the annular support member having the opening formed in the center, and the color wheel is configured by joining the end faces of the respective filter members. The number of manufacturing steps can be simplified, and a low-cost color wheel can be obtained. Further, by applying such a color wheel to a projector, a projector with reduced costs can be provided.
[Brief description of the drawings]
FIG. 1 is a view showing a color wheel according to a first embodiment of the present invention, FIG. 1 (a) is a plan view thereof, and FIG. 1 (b) is a sectional view taken along line X1-X1.
FIGS. 2A and 2B are diagrams showing a color wheel according to a second embodiment of the present invention, FIG. 2A being a plan view thereof, and FIG. 2B being a cross-sectional view taken along line X2-X2.
3A and 3B are views showing a color wheel according to a third embodiment of the present invention, FIG. 3A is a plan view thereof, and FIG. 3B is a view showing a filter member.
FIG. 4 is a plan view showing a color wheel according to a fourth embodiment of the present invention.
FIG. 5 is a diagram showing a cross section of a color wheel according to a fifth embodiment of the present invention.
FIG. 6 is a block diagram showing a main configuration of the projector according to the embodiment of the present invention.
FIG. 7 is a plan view showing a configuration of the optical system of FIG. 6;
FIG. 8 is a perspective view showing a color wheel according to a sixth embodiment of the present invention.
[Explanation of symbols]
10, 11, 12, 13, 14, 300: color wheel 20, 50: support member 21, 51: opening 48: end face 52: step 32, 34, 36, 72, 74, 76, 78: filter member 61, 62, 63, 80: cutout portion 100: projector 120: control portion 140: color wheel drive portion 150: DMD
160: lamp

Claims (17)

An annular support member having an opening formed in the center, and at least two filter members arranged on an outer peripheral portion of the annular support member,
Each of the at least two filter members has a first main surface, a second main surface opposed to the first main surface, and the first and second main surfaces between the first and second main surfaces. An end surface extending radially with respect to the central axis,
A color wheel, wherein at least a part of the second main surface is fixed to the support member, and an end surface of the filter member is joined to an end surface of another filter member. The color wheel according to claim 1, wherein the support member includes a step formed in a circumferential direction, and a second main surface of the filter member is positioned at the step. The color wheel according to claim 1, wherein the at least two filter members include a glass member having a predetermined thickness, and an end surface of the filter member includes a cut surface of the glass member. The color wheel according to claim 3, wherein the at least two filter members further include a coating layer for the filter on the glass member. The color wheel according to claim 1, wherein an end surface of the filter member is joined to an end surface of another filter member via an adhesive. The color wheel according to claim 1, wherein the opening of the support member is coupled to a rotation member of a motor. The color wheel according to any one of claims 1 to 6, wherein the at least two filter members include a filter member for transmitting light of substantially R, G, and B wavelengths. The color wheel according to any one of claims 1 to 7, wherein the at least two filter members include a filter member for transmitting substantially white light. 9. A notch is formed in at least one of the at least two filter members, and a cavity is formed by the notch when the at least two filter members are joined. The color wheel according to any of the above. The color wheel according to claim 9, wherein the notches are arranged at substantially equal intervals in a circumferential direction of the color wheel. A color wheel, wherein one color filter member is formed by combining filter members divided for each color. The color wheel according to claim 11, wherein the filter members for the different colors are fixed by an adhesive and integrally formed. A color wheel according to any one of claims 1 to 12, and rotating means coupled to the support member of the color wheel to rotate the color wheel,
A light source,
An illumination optical system that irradiates the color wheel with light from the light source, transmits light selected by a filter member of the color wheel, and performs illumination using the transmitted light. A color wheel according to any one of claims 1 to 13, and rotating means coupled to the support member of the color wheel to rotate the color wheel,
A light source,
Light modulation means;
Having projection means for projecting light modulated by the light modulation means,
A projector that irradiates light from the light source to the color wheel and irradiates light selected by a filter member of the color wheel to the light modulation unit. 15. The projector according to claim 14, wherein the light modulation unit includes a DMD. The projector according to claim 14, wherein the projector further includes a position changing unit that changes a position of the color wheel, and causes light from the light source to be incident on the cutout portion of the color wheel. 17. The projector according to claim 14, wherein the light source includes a discharge lamp, a reflector that reflects light from the discharge lamp, and a light transmission member that causes reflected light from the reflector to enter the color wheel.

Images