WO2008041363A1 - Projector - Google Patents

Abstract

A projector comprising a spatial light modulator (46), a control circuit (72) for controlling the spatial light modulator (46), a filter member (49) for transmitting/reflecting beams of different frequencies at a predetermined period, and a lens (48) for projecting modulation light from the spatial light modulator (46) onto a projection plane. The filter member (49) is arranged in the vicinity of the diaphragm position of the projection lens (48) or between the spatial light modulator (46) and the projection lens (48). Total time required by the filter member (49) for transmitting or reflecting two beams of different frequencies is 2%-50% of the above-mentioned period.

Description

 Specification

 Projection device

 Technical field

 The present invention relates to a projection apparatus that enlarges and displays an image using a spatial light modulator. More specifically, the present invention relates to a method for arranging color selection filters in a power sequential projector that obtains a color image by displaying projection light of different colors in time sequence.

 Background art

 Projectors using spatial light modulators such as transmissive liquid crystals, reflective liquid crystals, and micromirror arrays are known.

 A spatial light modulator has an array structure in which tens of thousands to millions of minute modulation elements are arranged.

Each pixel of the image displayed by the individual modulation elements is enlarged and displayed on the screen by the projection lens.

[0003] Spatial light modulators used in projectors are roughly divided into a liquid crystal device that modulates the polarization direction of incident light by sealing a liquid crystal between transparent substrates and applying a potential difference, and a fine MEMS (M i cro Electro Mechanic Systems) A micro mirror device that deflects a mirror with an electrostatic force and controls the direction of reflection of illumination light is generally used.

 [0004] An early example of the micromirror device is disclosed in USP4229732. It is disclosed that a drive circuit using a MOSFET is formed on a substrate, and a deformable metal mirror is also formed on the substrate. It is also disclosed that the mirror is deformed by the electrostatic force generated by the drive circuit and changes the reflection direction of incident light.

[0005] USP4662746 discloses an embodiment in which a mirror is held by one or two hinges. Specifically, when the mirror is held by one hinge, the hinge functions as a bending spring, and when the mirror is held by two hinges, the hinge functions as a torsion panel, causing the mirror to move in different directions. By tilting It is disclosed that the illumination light is deflected.

 [0006] Projectors using spatial light modulators are: a single-plate projector that performs display using one spatial light modulator and a multi-plate projector that performs display using a plurality of spatial light modulators. is there.

 White light emitted from the light source is separated into R, G, B by color separation means arranged in the optical path, irradiated to individual spatial light modulators assigned to each color, and modulated by each spatial light modulator An example of the configuration of a multi-plate projector that synthesizes light rays again by means of optical path synthesis means and then projects them with a projection lens is disclosed in USP4904061. USP4969730 discloses an optical configuration example corresponding to a reflective spatial light modulator.

[0007] The above-described multi-plate projection apparatus does not cause problems such as a decrease in light utilization efficiency and a color break (also referred to as "color break-up") as seen in the single-plate type described later. However, there are problems such as an increase in material costs due to the use of multiple spatial light modulators, an increase in adjustment man-hours, and a relatively complicated optical system. It is actually used only for some business purposes and high-end users.

[0008] On the other hand, a single-plate projection apparatus divides a period (one frame) for displaying one image into subframes, and irradiates one of R, G, and B illumination light within each subframe period. In addition to irradiating the spatial light modulator, the spatial light modulator sequentially displays images corresponding to each color in synchronization with the illumination light. Since the subframe period is set sufficiently short, the observer can integrate each color in the brain and recognize it as a color image. Here, the gradation (the number of reproduced colors in the case of color display) is determined by the minimum unit of time that the spatial light modulator sends the projection light to the projection optical path. That is, the gradation of the device is determined depending on the response speed of the spatial light modulator. For this reason, a micromirror device with a high response speed is more suitable than a liquid crystal device with a relatively low response speed as a spatial light modulator to be generally used in a single-plate projector. Hereinafter, a single-plate projection apparatus using a micromirror device as a spatial light modulator will be described in more detail.

 USP51 92946 discloses an embodiment of the above-described single-plate projector. In this apparatus, as shown in FIG. 1, the illumination light from the light source 1 is condensed on the lens 3 by the mirror 1 to form a light beam 4. The spatial light modulator 5 is controlled by the computer 6 and selectively reflects the illumination light toward the projection lens 7 to display an image on the screen 8. In this USP51 92946, the light source is a single laser or the color wheel is placed in the illumination optical path, so that the illumination light is concentrated at different frequencies and the illumination light is more than the critical flicker frequency of the human eye. A color image is obtained by time-sequential modulation in a fast period.

 [0010] As described above, the single-plate projector has only one spatial light modulator and has an advantage that the configuration of the optical system is simple. On the other hand, the contents of the display image, the movement of the observer's viewpoint, etc. There is a problem of a color break that is observed when the colors are separated by the above, and a decrease in light use efficiency due to the fact that light other than the light transmitted by the color wheel is not used for image display. Furthermore, the period in which the color wheel boundary crosses the illumination light flux is called the spoke time or blanking time, and the illumination light color changes every moment. During this period, the micromirror device is basically turned off. This is also a factor that reduces the light utilization efficiency.

[001 1] As a proposal to suppress the occurrence of color breaks, the color wheel can be rotated at a higher speed, or the color division of the power wheel can be subdivided as shown in Fig. 2, and each color within one frame can be divided. It is known to make the switching time of the above faster. In FIG. 2, the force wheel 1 0 1 and 1 0 2 are color-divided into three colors having three areas of R (Red), G (Green), and B (B l ue). It is a color wheel. However, the color division ratio differs between the color wheels 1 0 1 and 1 0 2. The color wheel 103 is a color wheel that is divided into four colors and has four regions R, G, B, and W (Wh i te). In addition, the color wheel 1 0 4 has an R area so that two areas of the same color face each other. It is a color wheel divided into three colors with a total of 6 areas, 2 areas, 2 G areas, and 2 B areas. The color wheel 10 5 is a color wheel that is divided into four colors, and has four regions of R, G, B, and Y (Yellow).

[0012] On the other hand, as one method for improving the light utilization efficiency, a configuration in which the light reflected by the color wheel is returned to the light source optical path and reused is known.

 Separation of illumination light and projection light (modulated light) is an important design item in a projection device using a reflective spatial light modulator. In a projection device using a micromirror device, there is a design example in which no separate element for illumination light and projection light is provided. However, when it is desired to give each element a degree of freedom, as shown in Fig. 3. In addition, separation of luminous flux ■ Addition element optical member. In the typical configuration of the single-plate projector shown in the figure, the light source light emitted from the light source 1 1 is collected by the condenser lens and incident on the rod integrator 1 2 to be uniform illumination light. After that, it is reflected or transmitted by a total reflection prism (hereinafter referred to as TIR prism) 1 3 and irradiated to the micromirror device 14. The TIR prism 13 separates the illumination light and the projection light from the illumination light on the micromirror device 変 調 4 and the projection light after modulation by the difference in the incident angle on the reflection surface. In the figure, the device configuration shown on the left is a configuration example in which a color wheel 15 is arranged in front of the rod integrator 12, and a part of the device shown on the right is a mouthpiece. This is a configuration example in which a color wheel 15 is arranged in the subsequent stage of the integer 1 2, and any configuration is applicable.

 On the other hand, in a projection apparatus using a reflective liquid crystal device, separation of illumination light and projection light is performed using a difference in polarization direction. In a reflective liquid crystal device, the polarization direction of illumination light is rotated 90 degrees to obtain output light. Therefore, separation of illumination light and projection light is performed using a polarization beam splitter.

[0014] By the way, unlike a spatial light modulator using liquid crystal, the micromirror device does not require polarization for illumination light because of its operating principle. In recent years, however, the use of polarized light has improved performance, or an alternative member that overcomes the disadvantages of conventional components. Peripheral members have been developed.

 As an alternative member of the color wheel, there is a wavelength-selective polarizing element using a laminated phase difference plate such as “Color Select” manufactured by Color Link Corporation. This device can output light by selectively rotating the polarization direction of polarized light. By combining this wavelength selective polarizing element and a liquid crystal element, the wavelength range of transmitted light can be switched to R, G, and B. Compared to the color wheel, there are no moving parts, no noise, fast switching speed, and the time equivalent to the spoke time can be shortened.

 [001 6] On the other hand, as a projection screen used in a projector apparatus, a screen whose characteristics are changed according to the polarization direction of incident light (hereinafter also referred to as a “polarizing screen”) has been proposed for the purpose of improving contrast. .

 [001 7] Furthermore, it is conceivable that the illumination light and the modulated light are separated by polarization in the same manner as in the reflection type liquid crystal device. As an option other than the optical system using the TIR prism, the design freedom can be achieved. Can expand the degree.

 [0018] As described above, although the micromirror device does not require polarization in principle, it can be combined with polarized light for the purpose of improving performance.

 However, in a projection apparatus in which an electrically controlled wavelength-selective polarizing element as an alternative to the color wheel is arranged in the illumination optical path, the light beam that has passed through the wavelength-selective polarizing element is further separated into the illumination projection light described above. It is considered that the polarization property of the projection lens deteriorates until it reaches the projection lens via the element and the spatial light modulator, and the maximum effect cannot be obtained by using in combination with the polarizing screen described above. Conceivable.

[001 9] —On the other hand, there is a structural problem caused by the conventional arrangement of the color wheel in the illumination optical path. Specifically, in a conventional color wheel arrangement, the color wheel is generally arranged such that its filter surface is perpendicular to the illumination optical axis. According to this arrangement, the physical size of the device housing in a plane perpendicular to the illumination optical axis is defined by the diameter of the color wheel, which may make it difficult to reduce the size of the housing. [0020] In view of the above circumstances, an object of the present invention is to provide a projection apparatus that can appropriately maintain the polarization of the projection light and can reduce the size of the apparatus.

 Regarding the projection device, the following technology is also disclosed.

 [0021] USP2393235 discloses a color flicker reducing apparatus (COLOR FL ICKER REDUCI NG APPARATUS). In this device, a force wheel is placed in front of the screen.

 [0022] USP5541679 and USP5669687 disclose an optical projection system (OPT I CAL PROJECT I ON SYSTEM). These systems are provided after the “Projection on stopper” which gives the “RGB pixel filter“ force ”Projection on aperture” and also determines the projection aperture. A filter is placed on the SLM (spatial light modulator) side of the diaphragm.

 [0023] USP5777781 discloses an optical projection system (OPT I CAL PROJECT I ON SYSTEM). In this system, the filter area through which the projection light passes is switched by changing the tilt angle of the thin film mirror.

 [0024] USP5993007 includes a reflection type projector (REFLECT I ON TYPE

 PROJECTOR) is disclosed. The claim of this patent includes a birefringent prism and two display devices, and a dependent claim is that a color filter is placed somewhere between the light source and the projection lens. F i g 3 discloses an embodiment in which a color wheel is arranged in the projection optical path. However, the advantage of placing a color filter in the projection optical path is not disclosed. Further, there is no disclosure that aims to obtain the merits (polarization maintenance, chromatic aberration correction, light intensity modulation) by limiting the arrangement position of the color filter to the projection optical path. Furthermore, with respect to the polarization maintenance, the embodiment disclosed in this patent cannot obtain polarized projection light.

[0025] USP6439724 discloses a color projector. The embodiment of this patent discloses a multi-plate projection apparatus in which the size of the panel and the distance from the projection lens are changed in order to correct chromatic aberration. Disclosure of the invention

 One aspect of the present invention is a projection apparatus using a spatial light modulator, characterized in that a frequency selection filter is arranged in the projection optical path.

 Brief Description of Drawings

 [0027] The present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

 FIG. 1 is a diagram showing an example of a conventional single-plate projector.

 FIG. 2 is a diagram showing an example of color division of a conventional color wheel.

 FIG. 3 is a diagram showing a typical configuration example of a conventional single-plate projector.

 FIG. 4 is a diagram illustrating a main configuration of a projection apparatus according to Embodiment 1.

 FIG. 5 is a diagram schematically showing a part of a micromirror device.

 FIG. 6 is a diagram illustrating a wavelength selective polarizing filter.

 FIG. 7 is a view showing a modification of the projection apparatus according to the first embodiment.

 FIG. 8 is a diagram showing a modification of the projection apparatus according to the first embodiment.

 FIG. 9 is a view showing a modification of the projection apparatus according to the first embodiment.

 FIG. 10 is a diagram showing a modification of the projection apparatus according to the first embodiment.

 FIG. 1 1 is a diagram showing a main configuration of a projection apparatus according to Embodiment 2.

 FIG. 12 is a view showing a modification of the color wheel.

 FIG. 13 is a view showing a modification of the color wheel.

 FIG. 14 is a diagram for explaining the relationship between a color wheel and a luminous flux.

 FIG. 15 is a view showing a modification of the projection apparatus according to the second embodiment.

 FIG. 16 shows a modification of the projection apparatus according to the second embodiment.

 FIG. 17 is a view showing a modification of the projection apparatus according to the second embodiment.

 FIG. 18 is a diagram for explaining an example of a color filter using the Fabry-Mouth one-interference method.

[Figure 19] A diagram showing an example of a color wheel designed to have a different thickness for each transmitted light.

FIG. 20 is a view showing a modification of the projection apparatus according to the second embodiment. FIG. 21 is a diagram showing a modification of the projection apparatus according to the second embodiment.

 FIG. 22 is a view showing a modification of the optical aperture member.

 FIG. 23 is a view showing a modification of the optical aperture member.

 FIG. 24 is a diagram for explaining a modification of the projection apparatus according to the second embodiment.

 FIG. 25 is a diagram for explaining a modification of the projection apparatus according to the second embodiment.

 FIG. 26 is a view showing a modification of the projection apparatus according to the second embodiment.

 FIG. 27 is a view showing a modification of a cylindrical color wheel.

 FIG. 28 is a diagram showing a modification of the projection apparatus according to the second embodiment.

 FIG. 29 is a diagram for explaining the modification shown in FIG. 28.

 FIG. 30 is a diagram for explaining the modification shown in FIG. 28.

 BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

 <Example 1>

 FIG. 4 is a diagram showing a main configuration of the projection apparatus according to Embodiment 1 of the present invention. In this projection apparatus, it is possible to reduce disturbance in the polarization direction of light emitted from the apparatus.

[0029] In the figure, the light source 31 is a high pressure mercury lamp, a xenon lamp, a composite light source that obtains multi-wavelength light by irradiating a phosphor with a monochromatic light source such as an LD or LED, and the generated illumination light is unpolarized. White light. The light source light generated from the light source is collected by the elliptical mirror 3 2 and is incident on the first fly-eye lens 3 3 a in which a plurality of condenser lenses are reduced and arranged in parallel. Near the position of the light source image generated by the first fly-eye lens 33a, a second fly-eye lens 33b that relays the light source image and projects it onto the micromirror device surface is disposed. Such a configuration reduces light intensity unevenness on the entire surface of the micromirror that is the irradiation surface. Here, the polarization conversion element 34 is disposed adjacent to the second fly-eye lens 33 b. The polarization conversion element 3 4 separates the incident illumination light into two polarization directions (S-polarized light and P-polarized light) with a polarization beam splitter. The S-polarized light is reflected by the polarization beam splitter surface and is emitted from the exit surface of the polarization conversion element 34. on the other hand, The P-polarized light passes through the polarization beam splitter, and then the polarization direction is rotated 90 degrees by the 1/2 λ phase difference plate provided on the exit surface of the polarization conversion element 34. As a result, the polarization direction of the illumination light output from the polarization conversion element 34 is only S-polarized light, and almost all of the illumination light can be used. In order to illuminate the spatial light modulator uniformly, there is also a method using the rod integrator described above. In this case, from the viewpoint of maintaining the polarization direction of the illumination light correctly, it is desirable that the polarization conversion element is disposed on the optical path on the exit surface side of the mouth dimmer.

Next, the illumination light is directed by the superimposing lens 36 for condensing the principal ray of each lens of the second fly-eye lens 33 b at the center of the micromirror device 35. Reflected at a desired angle by the TIR prism 37 toward the micromirror device 35. Here, the desired angle is the micro mirror (also simply referred to as “mirror 1”) of the micro mirror device (also simply referred to as “mirror 1 element” or “mirror-pixel”) of the micro mirror device 35. In a state where the mirror reflects the illumination light to the projection optical path at an angle determined by the tilt angle (also simply referred to as “ON state”), the emission direction is substantially perpendicular to the substrate of the micromirror device 35. It is an angle. In other words, as shown on the left side of FIG. 5, the inclination angle of the mirror 35a in the mirror element with respect to the device substrate 35b is 0, the incident angle of the illumination light with respect to the normal of the device substrate 35b and Then, the incident direction of the illumination light is determined so that φ = 20. In the figure, an example of a mirror in the ON state is shown on the left side, and an example of a mirror in the OFF state (a state in which the mirror reflects illumination light outside the projection light path) is shown in the center and right side.

 [0031] The micromirror device 35 according to the present embodiment has a plurality of microphone opening mirror elements arranged in an array, and each micromirror element has a microphone opening mirror. That is, the micromirror device 35 according to the present embodiment has a micromirror array composed of a plurality of micromirrors.

In FIG. 4, each micromirror formed on the micromirror device is shown. The micromirror of the element is individually controlled in tilt direction and displacement time according to a drive signal from a control circuit 71 (not shown in FIGS. 7 to 10 to be described later), and illuminating light along the projection optical path, Reflected as projection light. When the projection light is incident on the TIR surface at a critical angle or less, total reflection does not occur, and between the projection surface and the microphone mouth mirror device 35 (for example, near the aperture position of the projection lens 39 or the microphone mouth mirror) The light is incident on a wavelength selective polarizing filter 3 8 disposed between the device 3 5 and the aperture position of the projection lens 3 9. Here, as the wavelength selective polarizing filter 38, for example, a wavelength selective polarizing element using a laminated phase difference plate such as “Color Select” of the above-mentioned Color Link Inc. is used. A wavelength-selective polarizing element is an element that can output by rotating the polarization direction of polarized incident light in a wavelength-selective manner. It is possible to selectively switch areas. More specifically, as shown in FIG. 6, when the projection light incident on the wavelength selective polarizing filter 3 8 is white S-polarized light including R, G, B, for example, wavelength selective polarization Only the light in the specific wavelength range selected by the element 3 8 a is rotated by 90 degrees to become P-polarized light. Then, only the P-polarized light out of the projection light output from the wavelength-selective polarizing element 3 8 a is output by a polarizing element (Polyarizer) 3 8 b that transmits only P-polarized light. Therefore, the wavelength range of the transmitted light of the wavelength selective polarization filter 3 8 is changed to R, G, B by sequentially switching the light of the specific wavelength range selected by the wavelength selective polarization element 3 8 a to R, G, B. It becomes possible to switch to B sequentially. In the figure, the double arrows indicate the polarization direction of light. In the figure, for the convenience of explanation, a space is provided between the wavelength selective polarizing element 3 8 a and the polarizing element 3 8 b. It may consist of

As described above, the projection light incident on the wavelength selective polarizing filter 38 is, for example, white S-polarized light. The wavelength-selective polarizing filter 38 selectively converts light of an arbitrary frequency from incident projection light in a time-series and continuous manner and outputs it to the incident surface of the projection lens. As described above, according to the projection apparatus according to the present embodiment, since the element that determines the polarization direction of the projection light is arranged at the final stage incident on the projection lens 39, there is little disturbance in the polarization direction of the projection light. For example, in combination with a polarizing screen, a good image can be obtained. Moreover, it is only necessary to provide a filter area that is almost equal to the beam diameter, and unlike the conventional rotary color filter (color wheel), a large space for the beam diameter is not required.

 [0035] In the projection apparatus according to the present embodiment, the light incident on the micromirror device 35 may be P-polarized light or circularly-polarized light. The illumination light and projection light may be separated by a polarizing beam splitter (also simply referred to as “PBS”). In that case, a quarter-wave plate is placed in front of the micromirror device, and the incident light and projection light are projected. The light polarization direction may be rotated 90 degrees.

In the projection apparatus according to the present embodiment, in the wavelength selective polarizing filter 38, the wavelength selective polarizing element 38a and the polarizing element 38b are integrally configured and arranged in the projection optical path. For example, as shown in FIG. 7, it is also possible to arrange the wavelength selective polarizing element 3 8 a in the illumination optical path and arrange the polarizing element 3 8 b in the projection optical path. In the figure, double-headed arrows and double circles indicate the polarization direction of light (the same applies to FIGS. 8, 9, and 10). In the case of the example shown in FIG. 7, the polarization direction is changed by using the wavelength selective polarization element 3 8a only in the polarization direction of any one of the primary color lights out of the white light from the light source. The light transmitted through the wavelength selective polarizing element 3 8 a is white light including three primary colors as before input, but only one of the three primary colors can obtain illumination light having a different polarization direction from the other. . This illumination light is modulated and deflected into the projection optical path using a micromirror device 35. A polarizing plate which is a polarizing element 3 8 b is arranged in the projection optical path, and the direction is determined so as to transmit only the light beam whose polarization direction is different from the others. According to such a configuration, the polarization direction of the projection light is adjusted by the polarizing element 3 8 b arranged in the projection optical path, and the polarization direction is changed by the wavelength selective polarizing element 3 8 a arranged in the illumination optical path side. Color-sequential projection is possible by switching the colors to be used. Here, as shown in FIG. 8, the polarizing element 38 b arranged in the projection optical path is made rotatable and further rotated in synchronization with the wavelength selective polarizing element 38 a in the illumination optical path. For example, a single-color and two-color mixed color sequence as shown in the lower part of the figure can be performed, and the brightness of the image is improved by setting the total of one cycle of the two-color display period as the white display time. be able to. In the lower part of the figure, “Polarization direction” indicates the polarization direction of the light transmitted by the polarizing element 3 8 b after rotation, and “Output” is The output light of the polarizing element 3 8 b is shown. In the example of the figure, the polarizing element 38 b is not limited to the form shown in the figure, and may be a form in which individual polarizing plates having different polarization directions are joined.

 Further, as shown in FIG. 9, a liquid crystal element for intensity modulation (intensity modulation LCD 4 1 in FIG. 9) as shown in FIG. 25 described later is further added to the configuration shown in FIG. You may arrange in.

 In the configuration shown in FIG. 8, the monochromatic light and the two-color mixed light may be distributed to two separate spatial light modulators and modulated respectively.

 Further, in the configuration shown in FIG. 7, a configuration may be adopted in which at least one liquid crystal element is provided between the wavelength-selective polarizing element 3 8 a and the polarizing element 3 8 b. Further, in the projection apparatus according to the present embodiment, as shown in FIG. 10, it is possible to use a laser as the light source. In the example in the figure, a 1/2 λ wave plate (1/2; i wave pi ate) is placed in the optical path so that it can be inserted into and removed from the optical path of each individual laser source that emits R, G, and B illumination light. Has been. The polarization direction of the laser beam from the light source rotates 90 ° when a 1/2 λ wave plate is placed in the optical path. By repeating the operation of inserting a 1/2 λ wavelength plate only in the illumination light path related to one wavelength among the R, G, and 照明 illumination lights, the same as in the projection apparatus according to the above-described embodiment. The effect of can be obtained.

[0040] In addition, in the projection apparatus according to the present embodiment, when a reflection type polarization screen having different reflectivity depending on the polarization direction of incident light is applied as a screen for displaying a projection image by the projection lens 39, the reflection is performed. Type polarizing screen It is configured to have the highest reflectance with respect to the polarization direction of the shadow light. In addition, when a transmission type polarization screen whose transmittance varies depending on the polarization direction of incident light is used as the screen, the transmission type polarization screen has the highest transmittance in the polarization direction of the projection light. It is comprised so that it may become.

 [0041] In the projection apparatus according to the present embodiment, a so-called transmission type polarization element that transmits only light in a specific polarization direction is applied as the polarization element 3 8b. It is also possible to apply a so-called reflective polarizing element that reflects only light in the direction. In this case, the apparatus is configured such that only light having a specific polarization direction reflected by the reflective polarizing element is guided to the projection lens 39. For example, a polarization beam splitter (P B S) can be applied as the reflective polarizing element. In this case, the apparatus is configured such that only the light reflected by the polarizing beam splitter is guided to the projection lens 39. In addition, as the polarizing element 3 8 b, a polarizing element in which a plurality of polarizing elements having different polarization directions of transmitted light can be joined, or a plurality of polarizing elements having different polarization directions of reflected light can be applied. It is also possible to apply a material that has been joined. In this case, in accordance with the polarization direction of the light guided to the projection lens 39, a polarizing element that transmits or reflects light in the corresponding polarization direction is inserted into the projection optical path. <Example 2>

 FIG. 11 is a diagram showing a main configuration of a projection apparatus according to Embodiment 2 of the present invention. In this projection apparatus, it is possible to reduce the size of the apparatus housing in the optical axis direction of the apparatus.

 [0042] In the figure, the light from the light source incident on the micromirror device 46 is reflected by the TIR surface of the TIR prism 47 comprising the first prism and the second prism, and is reflected at a desired angle. The

[0043] Note that the micromirror device 46 according to the present embodiment also has a plurality of micromirror elements arranged in an array, like the microphone mirror device 35 according to the first embodiment. Each micromirror element has a micromirror. In other words, the micromirror device 46 according to the present embodiment also has a plurality of micromirrors. A micromirror array consisting of —. The light source according to the present embodiment is, for example, a laser light source or an LED light source.

 [0044] The micromirror of each micromirror element formed on the micromirror device is a control circuit 7 2 (FIGS. 15 to 17 described later, FIG. 20, FIG. 21, FIG. 26, and FIG. The direction of tilt and displacement time are individually controlled according to the drive signal from (2-8, not shown), and the illumination light is reflected as projection light along the projection light path. Projection light is incident on the TIR surface at a critical angle or less and does not generate total reflection, but is incident on a transmission-type force wheel 4 9 disposed between the projection lens 48 and the micromirror device 46. . Here, it is desirable that the color wheel 49 is disposed at a position where the projected light beam diameter becomes small at a position where it can be disposed. In general, the diameter of the projected light beam is the smallest at the stop position of the projection lens 48, and it is preferable to arrange the color wheel 49 in the vicinity thereof. A color wheel 49 can be arranged between the aperture positions of the micromirror device 46 and the projection lens 48.

 Here, the color wheel 49 may be held on the body by a lens holding member that holds the projection lens group.

 In addition, as shown in Fig. 12, reflection of unwanted light to the spatial light modulator is achieved by applying light absorption processing to the area other than the incident portion of the light beam in the color wheel 49 (black portion in the figure). It is possible to prevent unnecessary light from entering the projection lens 48. In the figure, “ED” indicates the effective diameter of the incident projected light beam. In addition, as shown in Fig. 13, an area other than the incident part of the light beam on the color wheel 49 is formed at an angle different from the color filter surface with respect to the optical axis, and unnecessary light is reflected outside the optical path. (Refer to planes 50a and 50b in the figure). In the figure, 51 denotes the rotation center axis of the color wheel 49.

[0046] When a micromirror device is used as a spatial light modulator as in this embodiment, the "ON" state in which the modulated light is reflected on the projection light path and the "OFF" state in which the light is reflected outside the projection light path The direction of movement of the optical axis when the It is desirable that the direction is such that it does not straddle different optical characteristic regions of the wheel.

 FIG. 14 is a diagram showing the relationship between the color wheel 49 and the luminous flux arranged in the projection optical path. In the figure, Θ is the angle formed by a straight line passing through the centers of the two color wheels that sandwich the effective luminous flux (the white part of the figure). On the other hand, the number of color divisions of color wheel 4 9 is n (three divisions in the figure). The number of times that the color wheel 4 9 rotates and crosses two color boundaries where the effective luminous flux is different is equal to n. In other words, the period in which the effective luminous flux straddles two color boundaries (hereinafter referred to as “color transition period”) during the rotation of the color wheel is 0 x n [deg.]. Regarding the control method of the spatial light modulator during this color transition period, it is common to control so that the modulated light is not guided to the projection optical path. With this control method, the longer the color transition period, the less efficient the illumination light is used. Moreover, in order to shorten the color transition period particularly in a projection apparatus using a color wheel, there is a problem that the color wheel has to be increased with respect to the beam diameter. However, the control itself is easy to control because it only needs to drive the spatial light modulator based on the signals corresponding to each RGB color. On the other hand, for the purpose of improving luminance in particular, there is known control for improving the efficiency of use of illumination light by guiding light modulated by a spatial light modulator to a projection light path even during a color transition period. However, a signal for white or mixed colors must be generated, which is complicated in terms of control, and the color purity decreases as the color transition period increases. In view of the above, in this embodiment, the wheel is set so that the color transition period is 2% ≤ (ΘXn) / 360≤50%, preferably 2% ≤ (ΘXn) / 360≤20%. Determine the diameter, beam diameter, and number of color divisions

As described above, according to the projection apparatus according to the present embodiment, the rotation axis of the color wheel 49 is substantially parallel to the optical axis of the projection lens 48, and the housing of the projection apparatus in the direction of the optical axis of the projection lens Miniaturization of body dimensions is facilitated. Since the color wheel 4 9 is arranged close to the micro mirror device 4 6, for example, the fin 1 can be provided on the color wheel 4 9 to cool the micro mirror device 4 6. . Projector with reduced size of device casing in optical axis direction of projection lens 48 described above Is particularly suitable, for example, for a wall-mounted projection device.

 Note that the projection apparatus according to the present embodiment can be modified in various ways as described below.

 First, in the projection apparatus according to the present embodiment, when the color wheel 4 9 is arranged in the projection optical path, a configuration as shown in FIG.

 [0050] In the figure, the micromirrors of each micromirror element formed on the micromirror device are individually controlled in inclination direction and displacement time in accordance with a drive signal from a control circuit 72, not shown, The light is reflected along the projection optical path as projection light. The projection light is incident on the TIR surface at a critical angle or less, and thus does not generate total reflection, but is incident on the color wheel 49 disposed between the projection lens 48 and the micromirror device 46. The light transmitted through the color wheel 49 is deflected by a folding mirror 52, which is a polarization mirror, and then enters the projection lens 48 and is projected. According to such a configuration, the height of the device can be made relatively thin except for the projection lens 48, and the size of the device can be reduced as in the device shown in FIG.

 Here, the color wheel 4 9 may be a reflection type filter (reflection type color wheel) 4 9 ′ as shown in FIG. According to such a configuration, the folding mirror 52 shown in FIG.

 [0052] In the above-described configuration, both the transmission type color wheel and the reflection type color wheel to be used may be arranged to be inclined with respect to the optical axis. By placing it at an angle, it is possible to improve space efficiency and to improve the contrast by controlling the reflection of unnecessary light.

Further, in the projection apparatus according to the present embodiment, a linearly moving color filter 53 as shown in FIG. 17 may be arranged instead of the color wheel 49. According to such a configuration, the outer shape of the filter can be made relatively small. Furthermore, by using a laser light source as the light source, the F value of the projection lens 48 can be increased while maintaining the same resolution as before. This makes it possible to reduce the diameter of the light beam in the projection optical path and to reduce the size of the color filter 53. . The color filter 53 may be a color filter using the Fabry-Perot interferometry as shown in FIG. In the color filter shown in the figure, a pair of reflective films having a reflectivity R are arranged in parallel with a minute gap. Here, the wavelength of the transmitted light can be selectively changed by changing the gap length d of the reflecting film using an actuator such as a piezo element.

[0054] Here, the transmittance t is

 t = (1-R) 2 / (1-R) 2 + 4Rsin2 ((5/2)

 δ = Απά / λ

 It is represented by Where R: reflectance, d: distance between reflection films, and λ: wavelength.

[0055] The frequency of transmitted light can be selected by adjusting the inter-reflective film distance d so that the transmittance becomes maximum at a desired wavelength λ. As a result, light (colored Iigh) of the selected frequency (wavelength) out of incident light (incident light) can be transmitted.

In the projection apparatus according to the present embodiment, as shown in FIG. 19, the color wheel or color filter to be used has a different thickness for each transmitted light (d 1, d 2, d It may be designed in 3) to correct the chromatic aberration (axial chromatic aberration) of the projection lens 48. In the projection lens, a so-called chromatic aberration is known in which the image forming position shifts for each color due to the difference in refractive index depending on the frequency of illumination light. In general, correction of chromatic aberration has been devised by combining a convex lens with a small refractive index difference by color and a concave lens with a large refractive index difference by color, or by combining lenses made of different types of glass. By arranging a wavelength selection filter in the projection optical path, the imaging position for each frequency can be adjusted.

[0057] As an example, the lens design is based on a wavelength of 550nm (green), and the axial chromatic aberration of wavelengths 656nm (red) and 470nm (blue) is AX (e), and the color wheel or color filter is refracted. When the rate is η (λ), the thickness correction amount Ad (λ) of the color wheel or color filter is

△ d U) = -AX U) / (1-1 / n U)) It becomes. The chromatic aberration of the projection lens can be corrected by setting the thickness of each color of the color wheel or color filter so that the above equation is satisfied.

 In addition, the projection apparatus according to the present embodiment can be configured to form an intermediate image between the micromirror device and the projection lens, as shown in FIG. In this case, the light modulated by the micromirror of the micromirror device 46 is imaged by the first projection lens 54 a. A field lens 5 5 for propagating projection light to the second projection lens 5 4 b is disposed at the image formation position by the first projection lens 5 4 a, and the first projection lens 5 4 An image of the exit pupil of a is formed at the entrance pupil position of the second projection lens 5 4 b. Here, the color wheel 49 is disposed in the vicinity of the field lens 55. According to such a configuration, the object-side focal length of the second projection lens 54b can be set short, and the beam diameter can be reduced by setting the magnification of the first projection lens 54b to 1x or less. As a result, the color wheel diameter can be reduced. Note that the color wheel 49 is near the aperture position of the first projection lens 54a, near the aperture position of the second projection lens 54b, or between the first projection lens 54a and the second projection lens. It is also possible to place it between the throttle positions of the sensors 5 4 b.

Further, in the projection apparatus according to the present embodiment, as shown in FIG. 21, the wavelength selection filter is arranged near the aperture position of the projection lens (for example, the aperture of the micromirror / chair 4 6 and the projection lens 48). It is also possible to arrange such that the intensity of the projection light can be adjusted. In this case, as shown in the figure, a substantially fan-shaped optical diaphragm member 5 7 is placed in the optical path by an actuator (for example, a mouthpiece, a solenoid, etc.) in the housing 56 holding the color wheel 49.保持 It is held so that it can be removed. In addition, A and B in the figure are the symbols used to clarify the positional relationship (the same applies to Fig. 23 described later). Since the optical aperture member 5 7 is arranged close to the aperture position of the projection lens 48, the amount of projection light is reduced by inserting the aperture in the optical path, and the brightness of the projection image is reduced without losing the projection image. It is possible. The form of the optical diaphragm member 57 is not limited to that shown in the figure. For example, the diaphragm form shown in FIG. It is possible to use a structure that uses variable squeezing blades, or an ND filter as shown in Fig. 23.

 In the projection apparatus according to the present embodiment, it is also possible to apply a color wheel composed of a color filter as shown in FIG. 24 in order to change the brightness of the projected image. The color wheel shown in the figure has a plurality of frequency selection filters and a concentric filter region having different transmittances (or reflectances). Furthermore, this color wheel is configured to be movable in the direction of the double arrow in the figure with respect to the luminous flux, and a frequency selective filter region having a high transmittance (or reflectance) in conjunction with the display image, and a transmittance ( Alternatively, a frequency selective filter having a low reflectivity can be selectively used. According to such a configuration, the intensity of the projection light can be changed without arranging the color wheel close to the aperture position of the projection lens.

 In the projection apparatus according to the present embodiment, a liquid crystal device as shown in FIG. 25 can be provided in order to change the brightness of the projection image. The liquid crystal device 58 is disposed at the same position with respect to the optical diaphragm and the brightness adjusting means having the mechanical operation described with reference to FIGS. 21 to 24 described above, and acts as a light quantity filter or an optical diaphragm. According to such a configuration, it is possible to reduce operating noise. In the right side of FIG. 25, the upper side shows the state when the liquid crystal device 58 acts as a light filter, and the lower side shows the state where the liquid crystal device 58 acts as an optical aperture. Shows the state.

 [0062] Here, in the configuration described with reference to Figs. 21 to 25, the brightness adjustment means for controlling the brightness of the projected image is not limited to the above-described embodiment. For example, a diaphragm that is directly inserted into and removed from the optical axis may be used, or the division shape of the filter regions having different transmittances may not be concentric. Further, the brightness adjusting means may be configured directly on the housing of the wavelength selection filter or may be individually installed.

As described above, according to the configuration described with reference to FIGS. 21 to 25, the amount of light emitted to the projection optical path can be controlled by the display image, and the conventional spatial light modulator can be used. Along with the gradation reproduction, more detailed gradation expression is possible. In addition, it is possible to make the black float (a phenomenon in which black becomes dark gray) due to stray light generated in the original spatial light modulator apparently light, and as a result, the dynamic range can be expanded. .

 Further, in the projection apparatus according to the present embodiment, as shown in FIG. 26, the color wheel can be formed in a cylindrical shape. In this case, as shown in the figure, the cylindrical surface of the cylindrical color wheel 59 is subjected to wavelength selection cues having different transmission frequencies. The inner diameter of the cylinder is set to a size that can accommodate the optical element (4 7) for guiding the illumination light to the micromirror device 46 and the micromirror device 46, and the micromirror device At least a part of the micromirror device 46 and the light guide optical element (47) are arranged so that the projection light from 46 passes through the wavelength selection coating surface. Included in 9. In this example, as shown in FIG. 27, the micromirror device 46 can be cooled by forming a fin structure for blowing air on the bottom surface of the cylindrical force roller wheel 59. Furthermore, the bottom of the cylindrical color wheel 59 is structured to absorb the OFF light from the micromirror device 46, or the OFF light is transmitted to the outside from the bottom of the cylindrical color wheel 59, It can also be absorbed by an external antireflection member. At this time, the external antireflection member may be cooled by the above-described cooling fins, and an air flow may be generated inside the cylindrical force roller to cool the micromirror device 46.

[0065] In the example described with reference to Figs. 26 and 27, the wavelength selection coat region with respect to the projected beam diameter becomes relatively narrow, and the blanking period increases. The rotation of one wheel 59 may be an unequal angular speed rotation. The unequal angular velocity rotation of the color wheel is not limited to this example, and may be applied to a normal disk-shaped color wheel. Further, in this example, the cylindrical color wheel 59 is arranged so as to contain the micromirror device 46, but it may be simply arranged in the projection optical path. [0066] In the example described with reference to FIG. 26 and FIG. 27, the color wheel is formed in a cylindrical shape. However, it can be formed in, for example, a substantially cylindrical shape and has a cross-section. It can also be formed in a polygonal cylindrical shape.

 Further, in the projection apparatus according to the present embodiment, as shown in FIG. 28, it is also possible to configure so that a cylindrical lens is arranged between the micromirror / chip and the projection lens. is there. In the figure, the configuration shown in the lower part is a cross-sectional view of the configuration shown in the upper part. In this case, as shown in the figure, the light source light incident on the micromirror device 46 is reflected by the TIR surface of the TIR prism 47 comprising the first prism and the second prism, and at a desired angle. Reflected. The micro mirror of each microphone mouth mirror element formed on the micro mirror device is individually controlled in the tilt direction and displacement time according to the drive signal from the control circuit 72, not shown, and the illumination light is projected along the projection optical path. And reflected as projection light. When the projection light is incident on the TIR surface at a critical angle or less, total reflection does not occur, and the projection light is directed to the exit surface of the TIR prism 47.

 A first cylindrical lens 60 a having power only in the direction perpendicular to the radial direction of the color wheel 49 is disposed on the exit surface of the TIR prism 47. Due to the action of the first cylindrical lens 60a, the luminous flux is a deformed luminous flux having a long side in the radial direction of the color wheel 4 9 as shown in Fig. 29 (described later). The part represented by The light beam that has passed through the color wheel 49 is disposed in the vicinity of the incident surface of the projection lens 48, and is incident on the second cylindrical lens 60b that corrects distortion of the light beam by the first cylindrical lens 60a. The light beam is corrected to a regular luminous flux shape and enters the projection lens 48.

FIG. 29 shows an example of the difference between the blanking time for a normal light beam and the blanking time for a light beam suitably deformed by the first cylindrical lens 60 a. In the figure, the portion represented by a circle 62 in the color wheel 4 9 shown in the upper part represents a normal light beam, and the portion represented by an ellipse 61 represents a light beam suitably deformed by the first cylindrical lens 60a. Indicates (irregular luminous flux) is doing. In the lower part of the figure, the upper side shows the blanking time (hatched area) for a normal light beam, and the lower side shows the blanking time (hatched line) due to a light beam (atypical light beam) deformed suitably by the first cylindrical lens 60a. Part). As shown in the figure, if the diameter of the color wheel is the same, the illumination light can be used more effectively in the case of the irregular light beam, and if the blanking time is the same as that in the case of the normal light beam, the figure 3 0 As shown in the figure, the diameter of the color wheel can be reduced. That is, the diameter 0 B of the color wheel shown in FIG. 30 <the diameter 0 A of the color wheel shown in FIG.

 In this example, the image to be displayed on the microphone mirror device 46 may be distorted in advance without using the second cylindrical lens 60 b. In this example, the NA (Numerical Aperture) of the illumination optical path is preferably asymmetric with respect to the optical axis in order to effectively capture the illumination light with respect to the first cylindrical lens 60 a. desirable. Further, when a light source having a plurality of light emitting parts such as a laser array or an LED array is used as a light source, if the direction of high NA of the non-symmetric NA is matched with the alignment direction of the plurality of light emitting parts, Is preferred.

 [0071] In addition, as described above, even when optical elements having different powers are used in the vertical and horizontal directions, the short side direction of the effective light beam is configured to cross the color region of the color wheel, and the blanking time is set. It is basically desirable to minimize

[0072] While the present invention has been described in detail above, the present invention is not limited to the above embodiment, and various improvements and modifications may be made without departing from the scope of the present invention. is there. For example, it is possible to apply a part of the configuration described in the second embodiment (including the modified example) to the configuration described in the first embodiment (including the modified example). It is also possible to apply a part of the configuration described in the first embodiment (including the modified example) to the configuration described in (including the example). In each example, the configuration described in the modified example is different from the configuration described in the modified example. It is also possible to apply a part of the configuration described in the modification. As described above, according to the present invention, the polarizability of the projection light can be maintained correctly, and the maximum effect can be obtained, for example, when used in combination with a polarizing screen. Further, in view of the downsizing of the apparatus configuration, it is possible to arrange a suitable optical member. By arranging a color filter in the projection optical path and providing each color filter region with different characteristics, it is possible to correct the chromatic aberration of the projection lens. The dynamic range can be expanded by arranging a color filter having a brightness modulation function at the aperture position of the projection lens.

Claims

The scope of the claims

 [1] a projection device,

 A light source;

 A spatial light modulator;

 A control circuit for controlling the spatial light modulator;

 A filter member that transmits or reflects light beams having different frequencies at a predetermined period, and a projection lens that projects the modulated light from the spatial light modulator onto a projection surface,

 The filter member is disposed in the vicinity of the aperture position of the projection lens or between the spatial light modulator and the aperture position of the projection lens, and simultaneously transmits or reflects light beams having two frequencies that differ depending on the filter member. The total amount of time is 2% or more and 50% or less of the period.

[2] The projection device according to claim 1,

 The spatial light modulator is a microphone mouth mirror device having a plurality of microphone mouth mirrors.

[3] The projection device according to claim 2,

 The moving direction of the projected light beam that is moved by the deflection of the micromirror is a direction that does not straddle regions having different optical characteristics of the filter member.

 [4] The projection device according to claim 1,

 The filter member determines a frequency of transmitted light or reflected light by inserting and extracting a filter having a different characteristic from an effective light flux of modulated light by the spatial light modulator at a predetermined period,

 The direction in which the filter regions having different characteristics of the filter member cross the effective light beam is the short side direction of the effective light beam.

[5] The projection device according to claim 1,

The filter member is disposed between the spatial light modulator and a stop position of the projection lens, and corrects axial chromatic aberration of the projection lens.

[6] The projection device according to claim 1,

 The filter member has a substantially cylindrical shape or a cylindrical shape having a polygonal cross section.

[7] The projection device according to claim 1,

 The filter member is a Fabry-Perot type color filter in which a pair of reflective films are arranged via a minute gap.

[8] The projection device according to claim 1,

 The filter member is configured to transmit light of a specific frequency and adjust the intensity of transmitted light.

[9] a projection device,

 A light source;

 A spatial light modulator;

 A control circuit for controlling the spatial light modulator;

 A filter member that transmits or reflects light beams having different frequencies at a predetermined period; a first projection lens that forms an image of modulated light from the spatial light modulator; and an image formed by the first projection lens is relayed. A second projection lens that projects onto the projection surface,

 Have

 The filter member includes a vicinity of an image plane formed by the first projection lens, a vicinity of a diaphragm position of the first projection lens, a vicinity of a diaphragm position of the second projection lens, or the first projection lens and the It is arranged between the aperture positions of the second projection lens.

[10] The projection device according to claim 9,

 The spatial light modulator is a microphone mouth mirror device having a plurality of microphone mouth mirrors.

[1 1] The projection device according to claim 10,

The direction of movement of the projected light beam that is moved by the deflection of the micromirror is a direction that does not straddle the regions having different optical characteristics of the filter member. Say it.

 [12] The projection device according to claim 9,

 The filter member determines a frequency of transmitted light or reflected light by inserting and extracting a filter having a different characteristic from an effective light flux of modulated light by the spatial light modulator at a predetermined period,

 The direction in which the filter regions having different characteristics of the filter member cross the effective light beam is the short side direction of the effective light beam.

[13] The projection device according to claim 9,

 The filter member is disposed between the spatial light modulator and a stop position of the projection lens, and corrects axial chromatic aberration of the projection lens.

[14] The projection device according to claim 9,

 The filter member has a substantially cylindrical shape or a cylindrical shape having a polygonal cross section.

[15] The projection device according to claim 9,

 The filter member is a Fabry-Perot type color filter in which a pair of reflective films are arranged via a minute gap.

[16] The projection device according to claim 9,

 The filter member is configured to transmit light of a specific frequency and adjust the intensity of transmitted light.

[17] a projection device,

 A plurality of illumination lights having different wavelengths and different polarization directions of at least one wavelength light, and

 A spatial light modulator;

 A control circuit for controlling the spatial light modulator;

 A projection lens that projects the modulated light from the spatial light modulator onto a projection surface; a polarizing element disposed in the projection optical path;

 Have

Transmitted or reflected by the polarizing element, and projected by the projection lens The wavelength of the illumination light is periodically changed.

 [18] The projection device according to claim 17,

 The polarizing element includes a plurality of polarizing filters that transmit or reflect light having different polarization directions.

[1 9] The projection device according to claim 17, wherein

 It further has at least one liquid crystal element between the filter member and the polarizing element.

[20] The projection device according to claim 17,

 A reflection or transmission screen for displaying an image projected by the projection lens;

 The reflective or transmissive screen is a polarizing screen that is most efficiently reflected or transmitted with respect to the polarization direction of incident light.

 [21] The projection device according to claim 17,

 The polarization direction of the illumination light is variable.

 [22] a projection device,

 A light source;

 A spatial light modulator;

 A control circuit for controlling the spatial light modulator;

 A filter member that converts the polarization direction of a light beam of a specific frequency differently from the others,

 A projection lens that projects the modulated light from the spatial light modulator onto a projection surface; a polarizing element disposed in the projection optical path;

 Have

 The filter member converts a polarization direction of a primary color that is periodically different from another, and the wavelength of the illumination light projected by the projection lens changes in the cycle.

[23] The projection device according to claim 22, wherein The polarizing element includes a plurality of polarizing filters that transmit or reflect light having different polarization directions.

 [24] The projection device according to claim 22, wherein

 It further has at least one liquid crystal element between the filter member and the polarizing element.

[25] The projection device according to claim 22, wherein

 A reflection or transmission screen for displaying an image projected by the projection lens;

 The reflective or transmissive screen is a polarizing screen that is most efficiently reflected or transmitted with respect to the polarization direction of incident light.

 [26] The projection device according to claim 22,

 The filter member has a substantially cylindrical shape or a cylindrical shape having a polygonal cross section.

[27] The projection device according to any one of claims 1 to 26,

 The projection light has a cross section that is asymmetric with respect to the optical axis.