JP4031481B2 - Projection display - Google Patents

Description

  The present invention relates to a projection display that projects and displays an image on a screen or the like.

  Conventionally, a projection display using liquid crystal (for example, see Patent Document 1 and Non-Patent Document 1) and a projection display using a DMD (Digital Micromirror Device) (for example, see Non-Patent Document 2) have been proposed. ing. These projection displays basically form an image to be projected on a screen by blocking light from a light source. In the case of a projection display using liquid crystal, extra light that is not projected onto the screen is absorbed by the liquid crystal surface, and in the case of a projection display using DMD, the extra light is directed in a direction different from the screen. It is scattered.

The applicant has not yet found prior art documents related to the present invention by the time of filing other than the prior art documents specified by the prior art document information described in this specification.
Japanese Patent Laid-Open No. 4-60538 Yoshikazu Suzuki, “Light source for information equipment”, Illumination Society of Japan, LS-95-1-6, 1995, p. 1-10 MAMignardi, “Digital Micromirror Array for Projection TV”, Solid State Technology, 1994, Vol. 37, no. 7, p. 63-64, 66, 68

  In a conventional projection display, a powerful light source is essential, and a high-intensity lamp such as a halogen lamp or an ultrahigh pressure mercury lamp is used. Although the luminous efficiency of these lamps is higher than that of a normal filament type, it is about 10%, and most of the electric power supplied to the lamps is released as heat. Even in a small desktop projector, the power consumption of the light source is 100 W to 200 W, and cooling with a fan or the like is indispensable. Therefore, the apparatus becomes large and the noise of the air cooling fan is also annoying. As described above, the conventional projection display has the problems that heat generation and power consumption are large, the apparatus is large, and the noise of the air cooling fan is large.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a projection display that is small in size and low in noise and generates little heat and power.

A projection display according to the present invention includes a light source that emits laser light, a mirror that is rotatably supported, and a drive electrode that is spaced apart from the mirror, and reflects the laser light by the mirror. In response to a MEMS mirror device that projects onto a projection target, mirror control means for repeatedly rotating the mirror at a predetermined frequency by supplying a voltage to the drive electrode, and a video signal synchronized with the rotation of the mirror A dichroic that is arranged between the light source and the MEMS mirror device, and synthesizes the three primary colors of laser light to enter the mirror of the MEMS mirror device. The three primary colors combined between the mirror, the dichroic mirror and the MEMS mirror device and synthesized by the dichroic mirror. A polarizing beam splitter cube that reflects the light to enter the mirror of the MEMS mirror device and transmits the reflected light from the mirror to project onto the projection target; the polarizing beam splitter cube; and the MEMS mirror device; A quarter-wave plate that polarization-modulates light passing therethrough, the light source is configured to make the laser beams of the three primary colors incident on the dichroic mirror, and the MEMS mirror device includes: A two-axis rotating MEMS mirror device in which the mirror rotates about two orthogonal axes, the mirror control means rotates the mirror in a horizontal direction and a vertical direction, and the modulation means , in accordance with the video signal of three primary colors in synchronism with rotation of the mirror, the laser light intensity modulated three primary colors from the light source intended to emit That.

In addition, the projection type display device of the present invention includes a light source for emitting a laser beam, and a rotatably supported mirror and drive electrodes which are spaced apart from the mirror, the laser beam by the mirror MEMS mirror device for reflecting and projecting onto a projection target, mirror control means for repeatedly rotating the mirror at a predetermined frequency by supplying a voltage to the drive electrode, and a video signal synchronized with the rotation of the mirror Accordingly, a dichroic that is arranged between the MEMS mirror device and the projection target and synthesizes the three primary colors of laser light and projects the projection onto the projection target. A mirror, a MEMS mirror that is arranged for each color of laser light between the light source and the MEMS mirror device and reflects the laser light from the light source A polarizing beam splitter cube that transmits the reflected light from the mirror and enters the dichroic mirror, and a laser beam of each color between the polarizing beam splitter cube and the MEMS mirror device. A quarter-wave plate that is arranged and polarization-modulates light passing therethrough, the light source is configured to cause the laser beams of the three primary colors to enter the corresponding polarization beam splitter cubes, and the MEMS mirror device includes: And a biaxially rotating MEMS mirror device provided for each laser beam of each color, in which the mirror rotates about two orthogonal axes, and the mirror control means horizontally moves the mirror of each MEMS mirror device. And the video signal of the three primary colors synchronized with the rotation of the mirror. In response, the laser light intensity modulated three primary colors from the light source is intended to emit.
In one configuration example of the projection display according to the present invention, at least one of the horizontal and vertical rotations of the mirror rotates at the natural vibration frequency of the mirror.
Also, in one configuration example of the projection display according to the present invention, the modulation means corrects the luminance value of the video signal in accordance with the moving speed of the light beam in the direction in which the mirror rotates at the natural vibration frequency. Is provided.

  According to the present invention, a laser with high luminous efficiency and low power consumption is used as a light source, the intensity of the laser light from this light source is modulated in accordance with the video signal, and the laser light is emitted by a small and low power consumption MEMS mirror device. Since the projection is deflected and projected onto the projection target, it is possible to realize a small-sized and low-noise projection display with low heat generation and power consumption.

  Further, by using two uniaxially rotating MEMS mirror devices in which the rotation axes of the mirrors are orthogonal to each other, the mirror can be easily controlled.

  In addition, by arranging a dichroic mirror between the light source and the MEMS mirror device and causing the laser light of the three primary colors to enter the dichroic mirror from the light source, a color image can be projected and displayed.

  Further, by using a polarizing beam splitter cube and a quarter wavelength plate, beam deflection can be performed efficiently when a biaxially rotating MEMS mirror device is used.

  Further, by providing a MEMS mirror device, a polarizing beam splitter cube, and a quarter wavelength plate for each color laser beam, it is possible to efficiently process laser beams of three colors having different wavelengths.

  Further, the MEMS mirror device can be driven with a low voltage by rotating at least one of the horizontal and vertical rotations of the mirror at the natural vibration frequency of the mirror.

  In addition, by correcting the luminance value of the video signal in accordance with the moving speed of the light beam in the direction in which the mirror rotates at the natural vibration frequency, the luminance on the projection target such as a screen can be made uniform.

[ Reference Example 1 ]
Hereinafter, reference examples of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a projection type display which is a reference example 1 of the present invention. The projection display shown in FIG. 1 includes semiconductor lasers 1-R, 1-G, and 1-B that emit laser beams of R (red), G (green), and B (blue), respectively, and a semiconductor laser 1-R. , 1-G, 1-B and the lenses 2-R, 2-G, 2-B for condensing laser light, respectively, reflect only red light, green light, and blue light, and transmit other light. The dichroic mirrors 3-R, 3-G, 3-B, a micro electro mechanical systems (MEMS) mirror device 4 having a mirror with a variable tilt angle, and the mirror of the MEMS mirror device 4 are rotated in the horizontal and vertical directions. And a control circuit 5 that emits laser light whose light intensity is modulated from the semiconductor lasers 1-R, 1-G, and 1-B in accordance with an input video signal. The control circuit 5 constitutes mirror control means and modulation means.

In the present reference example , a laser beam is projected onto the screen 6 using the MEMS mirror device 4 as a light beam deflector. The MEMS mirror device 4 is disclosed in, for example, Japanese Patent Application Laid-Open No. 2003-057575. 2 is an exploded perspective view showing the configuration of the MEMS mirror device disclosed in Japanese Patent Application Laid-Open No. 2003-057575, and FIG. 3 is a cross-sectional view of the MEMS mirror device of FIG.

As shown in FIGS. 2 and 3, four drive electrodes 103-1 to 103-4 are provided in the central portion of the lower substrate 101 made of single crystal silicon. Further, support columns 104 made of single crystal silicon are provided on both sides of the upper surface of the lower substrate 101.
On the other hand, an annular gimbal 202 is provided inside the upper substrate 201, and a mirror 203 is provided inside the gimbal 202. For example, three Ti / Pt / Au layers are formed on the surface of the mirror 203. The upper substrate 201 and the gimbal 202 are connected by two torsion springs 204 at 180 ° apart, and similarly the gimbal 202 and the mirror 203 are connected by two torsion springs 205 at 180 ° apart. . The x axis passing through the pair of torsion springs 204 and the y axis passing through the pair of torsion springs 205 are orthogonal to each other. As a result, the mirror 203 can rotate about the two axes of the x-axis and the y-axis. The upper substrate 201, the gimbal 202, the mirror 203, and the torsion springs 204 and 205 are integrally formed of single crystal silicon.

  The structure of the lower substrate 101 and the structure of the upper substrate 201 as shown in FIGS. 2 and 3 are separately manufactured, the upper substrate 201 is attached to the support column 104 by solder, and the upper substrate 201 is bonded to the lower substrate 101. ing. In the MEMS mirror device 4 as described above, the mirror 203 is grounded, a positive voltage is applied to the drive electrodes 103-1 to 103-4, and an asymmetric potential difference is generated between the drive electrodes 103-1 to 103-4. As a result, the mirror 203 can be attracted by an electrostatic force, and the mirror 203 can be rotated in an arbitrary direction.

  When the light beam was deflected by a conventional deflector, only a single stroke line drawing could be drawn, because the deflection speed of the deflector was slow. Conventionally used light beam deflectors include galvanometer mirrors. This galvanometer mirror is a device that changes the tilt angle of the mirror by electromagnetic force. However, since the mirror size is large and an electromagnetic drive mechanism is added to the mirror, the inertia is also large and a high-speed response cannot be realized. On the other hand, the MEMS mirror device 4 can reduce the dimension of the mirror 203 to mm or less, and drives the mirror 203 by electrostatic force, so that a deflector without extra mass for driving the mirror is configured. be able to.

  In the MEMS mirror device 4, it is easy to set the natural vibration frequency of the mirror 203 to about 10 kHz. When the mirror 203 is rotated in the horizontal direction at this natural vibration frequency, the light beam is deflected by the mirror 203. 20,000 lines can be projected onto the screen 6 per second. Further, when the mirror 203 is rotated at a frequency of 15 Hz in the vertical direction orthogonal to the direction of vibration, a two-dimensional image composed of about 600 projection lines can be projected 30 times per second. This two-dimensional image has a display resolution almost the same as that of a terrestrial television, and a display resolution that can be sufficiently put into practical use as a projection display. Of course, it is possible to increase the number of display lines by increasing the natural vibration frequency, and it is also possible to increase the display resolution by simultaneously using a plurality of configurations for projection. Since the mirror 203 is rotated at the natural vibration frequency, it can be driven at a low voltage.

  The control circuit 5 drives the MEMS mirror device 4 and modulates the intensity of the laser light projected on the screen 6. FIG. 4 is a block diagram showing the configuration of the control circuit 5. The control circuit 5 includes a synchronization signal separation unit 50, a synchronization signal generation unit 51, a mirror driver 52, an A / D converter 53, a compression / scaling unit 54, a video memory 55, and a vertical scanning direction conversion unit 56. A horizontal scanning direction conversion unit 57, a luminance normalization unit 58, a color separation unit 59, D / A converters 60-R, 60-G, 60-B, and LD drivers 61-R, 61-G. , 61-B.

  The synchronization signal separation unit 50 separates the vertical synchronization signal V1 and the horizontal synchronization signal H1 from the input video signal VIN. The synchronization signal generator 51 generates a frame synchronization signal V2 and a horizontal synchronization signal H2 corresponding to the frame synchronization frequency and horizontal synchronization frequency of the projection display.

  The mirror driver 52 applies a drive voltage based on the frame synchronization signal V2 and the horizontal synchronization signal H2 to the drive electrodes 103-1 to 103-4 of the MEMS mirror device 4. Thereby, the mirror 203 of the MEMS mirror device 4 repeats the horizontal rotation (for example, the rotation around the y axis in FIG. 2) at the frequency of the horizontal synchronization signal H2, and at the same time the vertical synchronization at the frequency of the frame synchronization signal V2. The rotation (rotation around the x axis in FIG. 2) is repeated. Regarding the horizontal rotation, when the state A returns to the state A again from the state A in FIG. 3 through the state B, it becomes one cycle, and this cycle is repeated at the frequency of the horizontal synchronizing signal H2. The same rotation is repeated in the vertical direction at the frequency of the frame synchronization signal V2.

On the other hand, the A / D converter 53 converts the analog input video signal VIN into digital video data in synchronization with the vertical synchronizing signal V1 and the horizontal synchronizing signal H1. Here, the frame synchronization frequency and the horizontal synchronization frequency of the projection display of this reference example are different from the vertical synchronization frequency and the horizontal synchronization frequency of the input video signal VIN. Therefore, the compression / scaling unit 54 performs conversion processing on the video data output from the A / D converter 53 in accordance with the frame synchronization frequency and horizontal synchronization frequency of the projection display. The video memory 55 stores the converted video data in units of frames.

By the way, in a conventional TV receiver or the like, scanning from left to right of an electron beam is counted as one horizontal scanning, and movement from right to left is used as a blanking period. Similarly, the scanning from the top to the bottom of the electron beam is counted as one vertical scanning, and the movement from the bottom to the top is defined as a blanking period. In contrast, in the projection display device of the present embodiment, scanning from left of the laser beam to the right (hereinafter, referred to as right scan) stands at one of the horizontal scanning, further scanning from right to left (hereinafter (Referred to as leftward scanning) is also counted as one horizontal scanning. Similarly, scanning from the top to the bottom of the laser beam (hereinafter referred to as downward scanning) is counted as one vertical scanning, and scanning from the bottom to the top (hereinafter referred to as upward scanning) is also referred to as one vertical scanning. count.

  Therefore, assuming that the order of video data stored in the video memory 55 corresponds to rightward scanning and downward scanning, the horizontal alignment of video data is reversed in the case of leftward scanning and the reverse order of that in the case of rightward scanning. Similarly, in the case of upward scanning, it is necessary to rearrange the video data in the vertical direction in the reverse order to that in the case of downward scanning.

The vertical scanning direction conversion unit 56 converts the vertical arrangement of the video data corresponding to the upward scanning among the video data in units of frames output from the video memory 55 in synchronization with the frame synchronization signal V2 and the horizontal synchronization signal H2. A conversion process for rearranging in reverse order is performed.
On the other hand, the horizontal scanning direction conversion unit 57 converts the horizontal arrangement of the video data corresponding to the leftward scanning out of the video data in units of frames subjected to the conversion processing by the vertical scanning direction conversion unit 56 in the reverse order. Process.

  Next, since the horizontal rotation of the mirror 203 is a single vibration due to the frequency of the horizontal synchronization signal H2 (the natural vibration frequency of the mirror 203), the scanning speed is fast near the center of the screen 6, and near the edge of the screen 6. The scanning speed becomes slow. Therefore, even if the luminance value of the video data is uniform, the central portion becomes dark and the peripheral portion becomes bright on the screen 6. Therefore, the luminance normalization unit 58 obtains a coefficient that is proportional to the horizontal movement speed of the light beam on the screen 6 in the horizontal direction of the video data and the same in the vertical direction from the horizontal scanning direction conversion unit 57. By applying the output video data, the luminance value of the video data is corrected in the horizontal direction. As a result, the beam intensity is corrected in accordance with the moving speed of the light beam on the screen 6, so that the luminance on the screen 6 becomes uniform if the luminance of the video data is uniform.

  In addition, since the scanning in the vertical direction can be performed by forced vibration with a constant scanning speed because the frame synchronization frequency is low, it is not necessary to correct the luminance in the vertical direction. When the vertical rotation of the mirror 203 is also a single vibration, it is necessary to correct the luminance as in the horizontal direction. In this case, the coefficient applied to the video data is proportional to the horizontal moving speed of the light beam on the screen 6 in the horizontal direction of the video data, and the vertical movement of the light beam on the screen 6 in the vertical direction. A coefficient proportional to the speed may be used.

  The color separation unit 59 converts the video data corrected by the luminance normalization unit 58 into red, green, and blue primary color data. The D / A converters 60-R, 60-G, and 60-B convert the red video data, the green video data, and the blue video data output from the color separation unit 59 into analog signals, respectively.

  The LD driver 61-R emits a red laser beam whose light intensity is modulated in accordance with the red video signal output from the D / A converter 60-R from the semiconductor laser 1-R, and the LD driver 61-G The green laser light whose light intensity is modulated in accordance with the green video signal output from the D / A converter 60-G is emitted from the semiconductor laser 1-G, and the LD driver 61-B includes the D / A converter 60-G. A blue laser beam whose light intensity is modulated in accordance with the blue video signal output from B is emitted from the semiconductor laser 1-B.

  The red, green, and blue laser beams emitted from the semiconductor lasers 1-R, 1-G, and 1-B are condensed by the lenses 2-R, 2-G, and 2-B, respectively, and are dichroic mirror 3-R. , 3-G, 3-B. The dichroic mirror 3-R reflects red laser light from the lens 2-R. The dichroic mirror 3-G reflects the green laser light from the lens 2-G and transmits the red laser light from the dichroic mirror 3-R. The dichroic mirror 3-B reflects the blue laser light from the lens 2-B and transmits the red laser light and the green laser light from the dichroic mirror 3-G. In this way, red, green, and blue laser beams are combined by the dichroic mirrors 3-R, 3-G, and 3-B.

  The mirror 203 of the MEMS mirror device 4 reflects and projects the three primary color laser beams from the dichroic mirrors 3-R, 3-G, and 3-B onto the screen 6. As described above, since the mirror 203 rotates in the horizontal direction and the vertical direction, the screen 6 is scanned with the laser beam, and a two-dimensional image corresponding to the input video signal VIN is projected and displayed on the screen 6. Is done.

As described above, according to this reference example , the semiconductor lasers 1-R, 1-G, and 1-B having high luminous efficiency and low power consumption are used as light sources, and the laser light from the light sources is used as video signals. Accordingly, intensity modulation is performed, and the laser beam is deflected and projected onto the screen 6 by the small-sized and low power consumption MEMS mirror device 4, so that a projection display with low heat generation and low power consumption can be realized. The luminous efficiency of semiconductor lasers exceeds 60%, and high-power products with an output of about 0.1 W have been developed for the three primary colors of visible light. In addition, according to the present reference example , each component of the projection display can be reduced, and an air-cooling fan is unnecessary, so that a small and low noise projection display can be realized. Since a projection lens and a focusing mechanism necessary for a conventional liquid crystal projector are not necessary, a very compact projection display can be configured in combination with the absence of a cooling mechanism.

  It can be seen that the angular resolution of the human eye is about 0.02 degrees from the size of the photoreceptor and eyeball. This numerical value means that there is only a resolution of 0.35 mm at 1 m ahead and 1 mm at 3 m ahead. Since the diameter of the laser beam can be reduced to about 400 μm, an image with sufficiently high resolution can be projected by scanning the laser beam.

[ Reference Example 2 ]
In Reference Example 1 , a biaxially rotated MEMS mirror device is used as a deflector, but a uniaxially rotated MEMS mirror device may be used. FIG. 5 is a block diagram showing a configuration of a projection display that is a reference example 2 of the present invention. The same components as those in FIG. 1 are denoted by the same reference numerals.

  The mirror of the MEMS mirror device 4a for vertical scanning rotates about the x axis, and the mirror of the MEMS mirror device 4b for horizontal scanning rotates about the y axis orthogonal to the x axis. The configuration of the MEMS mirror devices 4a and 4b is almost the same as that of the MEMS mirror device 4 shown in FIGS. 2 and 3, but a two-part drive electrode is provided in place of the four-part drive electrodes 103-1 to 103-4. It is done. For example, in the case of the MEMS mirror device 4a, two electrodes are formed on the lower substrate so as to face each other with the x axis interposed therebetween. In the case of the MEMS mirror device 4b, two electrodes are formed on the lower substrate so as to face each other with the y-axis interposed therebetween. In the case of uniaxial rotation, it is not necessary to provide the gimbal 202 as shown in FIGS. 2 and 3, and the mirror may be connected to the upper substrate via a torsion spring.

The operations of the semiconductor lasers 1-R, 1-G, 1-B, the lenses 2-R, 2-G, 2-B, and the dichroic mirrors 3-R, 3-G, 3-B are the same as those in the first reference example. is there.
Although the configuration of the control circuit 5a is also almost the same as the control circuit 5 of Reference Example 1, it is different from Example 1 in which the mirror driver control circuit 5a controls the MEMS mirror device 4a, and 4b individually.

  In other words, the mirror driver of the control circuit 5a applies a drive voltage based on the frame synchronization signal V2 to the drive electrode of the MEMS mirror device 4a, thereby causing the mirror of the MEMS mirror device 4a to rotate in the vertical direction at the frequency of the frame synchronization signal V2. Let the movement repeat. Further, the mirror driver applies a driving voltage based on the horizontal synchronizing signal H2 to the driving electrode of the MEMS mirror device 4b, thereby causing the mirror of the MEMS mirror device 4b to repeat the horizontal rotation at the frequency of the horizontal synchronizing signal H2. .

Thus, also in the present embodiment, it is possible to obtain the same effect as in Reference Example 1. According to this reference example , the mirror can be easily controlled by separating the MEMS mirror device 4b that performs high-speed beam deflection in the horizontal direction and the MEMS mirror device 4a that performs low-speed beam deflection in the vertical direction. it can.

  In order to maximize the deflection efficiency of the light beam, it is possible to arrange the two MEMS mirror devices so that the beam plane including the incident light and the reflected light is orthogonal to the rotation axis of the mirror in each MEMS mirror device. preferable. That is, the MEMS mirror device 4a is disposed so that the beam plane including incident light and reflected light is orthogonal to the x axis, and the MEMS mirror device 4b is disposed so that the beam plane is orthogonal to the y axis. preferable.

  However, in the case of the MEMS mirror device 4b in the subsequent stage, since the beam is deflected by the MEMS mirror device 4a, strictly speaking, in all cases, it is difficult to make the beam plane orthogonal to the y axis. Therefore, when the mirror of the MEMS mirror device 4a is in a state where the tilt angle is 0, the MEMS mirror device 4b so that the beam plane including the incident light incident on the mirror of the MEMS mirror device 4b and the reflected light thereof is orthogonal to the y-axis. May be arranged.

[ First Embodiment ]
In Reference Example 1 and Reference Example 2 , it is necessary to make the laser light incident obliquely on the mirror surface of the MEMS mirror device, but the MEMS mirror device is arranged so that the axis of the mirror is orthogonal to the incident beam. Thus, when the mirror is rotated by θ, the beam is deflected by 2θ, and this configuration is most efficient. On the other hand, when the beam and the mirror axis are not orthogonal, if the angle between the mirror and the beam is φ (φ <90 °), the deflection angle of the beam is 2θ sinφ when the mirror is rotated by θ. Inefficiency. When using two of the MEMS mirror device of uniaxial rotation as in the second embodiment, but can take a good arrangement most deflection efficiency for both mirrors, the biaxially-turning of Reference Example 1 In the case of the MEMS mirror device, the deflection efficiency is always deteriorated with respect to one axis.

Therefore, in the present embodiment, by using the polarization beam splitter cube and the quarter wavelength plate, the beam is incident on the mirror from the direction orthogonal to the x axis and the y axis of the MEMS mirror device. FIG. 6 is a block diagram showing the configuration of the projection display according to the first embodiment of the present invention. The same components as those in FIG. 1 are denoted by the same reference numerals. A MEMS mirror device 4 and the control circuit 5 is the same as in Reference Example 1.

  Due to the structure of the semiconductor lasers 1-R, 1-G, and 1-B, the output light is linearly polarized. In the present embodiment, the polarization planes of the three colors of red, green, and blue laser light emitted from the semiconductor lasers 1-R, 1-G, and 1-B are matched. The three primary color laser beams synthesized by the dichroic mirrors 3-R, 3-G, and 3-B are reflected by the polarization beam splitter cube 7 and enter the quarter-wave plate 8. The three primary color laser beams are converted into circularly polarized waves by the quarter wavelength plate 8 and enter the mirror 203 of the MEMS mirror device 4 from directions orthogonal to the x axis and the y axis. Since the phase of the light reflected by the mirror 203 is reversed, the rotation direction of the circularly polarized wave is reversed with the incident light to the mirror 203.

The reflected light from the mirror 203 is converted into linearly polarized light by the quarter-wave plate 8 and becomes polarized light orthogonal to the light when entering the polarizing beam splitter cube 7, and travels straight through the polarizing beam splitter cube 7. Then, the screen 6 is reached.
Thus, according to this embodiment, it is possible to obtain the same effect as in Reference Example 1, further can be performed efficiently beam deflection as compared with Reference Example 1.

[ Second Embodiment ]
The polarizing beam splitter cube and the quarter wave plate generally have wavelength dependency. Therefore, as in the first embodiment, it can be difficult to efficiently processed using the same polarizing beam splitter cube 7 and the quarter-wave plate 8 with respect to laser beams of three colors having different wavelengths is there.

Therefore, in this embodiment, a polarization beam splitter cube and a quarter wavelength plate are provided for each laser beam. FIG. 7 is a block diagram showing the configuration of the projection display according to the second embodiment of the present invention. The same components as those in FIGS. 1 and 6 are given the same reference numerals. In the present embodiment, the MEMS mirror devices 4-R, 4-G, 4-B and the polarizing beam splitter cubes 7-R, 7-G, 7-B and 1/4 are respectively provided for the red, green, and blue laser beams. Wave plates 8-R, 8-G, and 8-B are provided. Dichroic mirrors 3-R, 3-G, 3-B are provided between the polarization beam splitter cubes 7-R, 7-G, 7-B and the screen 6.

  The red laser light emitted from the semiconductor laser 1-R is reflected by the polarization beam splitter cube 7-R, passes through the quarter-wave plate 8-R, is reflected by the mirror of the MEMS mirror device 4-R, and is again 1 The light passes through the / 4 wavelength plate 8-R and enters the dichroic mirror 3-R. On the other hand, the green laser light emitted from the semiconductor laser 1-G is reflected by the polarization beam splitter cube 7-G, passes through the quarter wavelength plate 8-G, and is reflected by the mirror of the MEMS mirror device 4-G. The light again passes through the quarter-wave plate 8-G and enters the dichroic mirror 3-G. Similarly, the blue laser light emitted from the semiconductor laser 1-B is reflected by the polarization beam splitter cube 7-B, passes through the quarter wavelength plate 8-B, and is reflected by the mirror of the MEMS mirror device 4-B. Then, it passes through the quarter-wave plate 8-B again and enters the dichroic mirror 3-B.

Then, red, green, and blue laser beams are combined by dichroic mirrors 3-R, 3-G, and 3-B and projected onto the screen 6.
The configuration of the MEMS mirror device 4-R, 4-G, 4-B is the same as that of the MEMS mirror device 4 of Reference Example 1 , and the configuration of the control circuit 5b is the same as that of the control circuit 5. The mirror driver of the control circuit 5b supplies the same drive voltage to the MEMS mirror devices 4-R, 4-G, and 4-B, respectively. Thereby, the mirrors of the MEMS mirror devices 4-R, 4-G, 4-B rotate in synchronization with each other.

Thus, according to the present embodiment, the same effects as those of the first embodiment can be obtained, and three-color laser beams having different wavelengths can be efficiently processed as compared with the first embodiment. Can do.

  Although the optical path length is not considered in FIG. 7 for ease of description, the final stage dichroic mirror (3-B in the example of FIG. 7) and each MEMS mirror device 4-R, 4-G, 4 If the optical path lengths between the mirrors of −B are made equal, if the tilt angles of the mirrors of the MEMS mirror devices 4-R, 4-G, and 4-B are the same, beams of three colors appear from the same position. Outputting with the same deflection angle makes it possible to avoid color misregistration on the screen 6.

[ Third Embodiment ]
By taking advantage of the small size of the projection display of the present invention, it is possible to draw directly on the retina instead of projecting to the screen. FIG. 8 is a block diagram showing the configuration of a projection display according to the third embodiment of the present invention. The same components as those in FIG. 1 are denoted by the same reference numerals. In this embodiment, lenses 9, 10 and a half mirror 11 are added to Reference Example 1 , and the projection display shown in FIG. 8 is provided in a helmet, goggles, or the like that is mounted on a human head. The half mirror 11 is disposed in front of the eyeball when a helmet or goggles are worn on the head.

Similar to Reference Example 1 , the three primary color laser beams deflected by the mirror of the MEMS mirror device 4 pass through the lenses 9 and 10 and are reflected by a filter that reflects a specific wavelength, such as a half mirror (or dichroic mirror) 11. And projected onto the retina. Thus, a person wearing a helmet or goggles sees an image in which the surrounding scenery projected through the half mirror 11 and projected onto the retina overlaps the image reflected by the half mirror 11.

In Reference Example 1 and Reference Example 2 and the first to third embodiments, the case of a small projection display using a semiconductor laser has been described. However, the application of the present invention is limited to this. However, it goes without saying that projection display on a larger screen is possible by using a large-sized laser light source such as a solid-state laser or a dye laser.

  The present invention can be applied to a projection display that displays an image by projecting it on a screen or the like.

It is a block diagram which shows the structure of the projection type display used as the reference example 1 of this invention. It is a disassembled perspective view which shows the structure of the MEMS mirror apparatus of the projection type display of FIG. It is sectional drawing of the MEMS mirror apparatus of FIG. It is a block diagram which shows the structure of the control circuit of the projection type display of FIG. It is a block diagram which shows the structure of the projection type display used as the reference example 2 of this invention. It is a block diagram which shows the structure of the projection type display used as the 1st Embodiment of this invention. It is a block diagram which shows the structure of the projection type display used as the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the projection type display used as the 3rd Embodiment of this invention.

Explanation of symbols

1-R, 1-G, 1-B ... semiconductor laser, 2-R, 2-G, 2-B, 9, 10 ... lens, 3-R, 3-G, 3-B ... dichroic mirror, 4, 4a, 4b, 4-R, 4-G, 4-B ... MEMS mirror device, 5, 5a, 5b ... control circuit, 6 ... screen, 7, 7-R, 7-G, 7-B ... polarizing beam splitter Cube, 8, 8-R, 8-G, 8-B ... 1/4 wavelength plate, 11 ... Half mirror, 50 ... Sync signal separator, 51 ... Sync signal generator, 52 ... Mirror driver, 53 ... A / D converter 54... Compression / scaling unit 55. Video memory 56. Vertical scanning direction conversion unit 57 57 Horizontal scanning direction conversion unit 58. Luminance normalization unit 59. Color separation unit 60-R, 60 -G, 60-B ... D / A converter, 61-R, 61-G, 61-B ... LD driver.

Claims (4)

A light source that emits laser light;
A MEMS mirror device that includes a mirror that is rotatably supported and a drive electrode that is spaced apart from the mirror, and reflects the laser light by the mirror to project it onto a projection target;
Mirror control means for repeatedly rotating the mirror at a predetermined frequency by supplying a voltage to the drive electrode;
Modulation means for emitting intensity-modulated laser light from the light source in response to a video signal synchronized with rotation of the mirror ;
A dichroic mirror that is disposed between the light source and the MEMS mirror device and synthesizes three primary colors of laser light to enter the mirror of the MEMS mirror device;
It is arranged between the dichroic mirror and the MEMS mirror device, reflects the laser beams of the three primary colors synthesized by the dichroic mirror to enter the mirror of the MEMS mirror device, and transmits the reflected light from this mirror A polarizing beam splitter cube for projecting onto the projection target,
A quarter-wave plate disposed between the polarizing beam splitter cube and the MEMS mirror device for polarization-modulating light passing therethrough,
The light source is for causing the laser beams of the three primary colors to enter the dichroic mirror,
The MEMS mirror device is a two-axis rotating MEMS mirror device in which the mirror rotates around two orthogonal axes.
The mirror control means rotates the mirror in a horizontal direction and a vertical direction,
The projection unit radiates laser light of three primary colors whose intensity is modulated from the light source according to a video signal of three primary colors synchronized with the rotation of the mirror . A light source that emits laser light;
A MEMS mirror device that includes a mirror that is rotatably supported and a drive electrode that is spaced apart from the mirror, and reflects the laser light by the mirror to project it onto a projection target;
Mirror control means for repeatedly rotating the mirror at a predetermined frequency by supplying a voltage to the drive electrode;
Modulation means for emitting intensity-modulated laser light from the light source in response to a video signal synchronized with rotation of the mirror;
A dichroic mirror that is disposed between the MEMS mirror device and the projection target and synthesizes the three primary colors of laser light and projects the resultant to the projection target;
It is arranged for each color laser beam between the light source and the MEMS mirror device, reflects the laser beam from the light source to enter the mirror of the corresponding MEMS mirror device, and transmits the reflected light from this mirror. A polarizing beam splitter cube to be incident on the dichroic mirror,
A quarter wave plate that is arranged for each color laser beam between the polarizing beam splitter cube and the MEMS mirror device, and that polarizes and modulates the light passing therethrough,
The light source is configured to cause the laser beams of the three primary colors to enter the corresponding polarizing beam splitter cubes,
The MEMS mirror device is a biaxially rotated MEMS mirror device provided for each laser beam of each color, in which the mirror rotates around two orthogonal axes.
The mirror control means rotates the mirror of each MEMS mirror device in the horizontal direction and the vertical direction, respectively.
The projection unit radiates laser light of three primary colors whose intensity is modulated from the light source according to a video signal of three primary colors synchronized with the rotation of the mirror . The projection display according to claim 1 or 2,
At least one of the horizontal and vertical rotations of the mirror rotates at the natural vibration frequency of the mirror . The projection display according to claim 3 , wherein
The projection type display device characterized in that the modulation means includes means for correcting the luminance value of the video signal in accordance with the moving speed of the light beam in the direction in which the mirror rotates at the natural vibration frequency .

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