JP2007079088A - Image display apparatus and method for controlling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display apparatus or the like which displays a flicker-reduced and high-quality image by improving the refresh rate of the image and reducing the scanning speed of a light beam. <P>SOLUTION: The image display apparatus for displaying an image by using a light beam modulated in accordance with an image signal comprises: a light source part 121R for supplying at least two beams of the same color; and a scanning part 200 for scanning the beams from the light source part 121R in an irradiated area in an X direction which is the first direction and in a Y direction which is a second direction approximately orthogonal to the first direction. The scanning part 200 is driven so that a frequency for scanning a beam in the X direction is higher than a frequency for scanning a beam in the Y direction, and when the frequency of a synchronizing signal in the Y direction which is the second direction is p, m pieces of beams are scanned in the Y direction by a frequency higher than p/m and lower than the p. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image display device and a method for controlling the image display device, and more particularly to a technique of an image display device that displays an image by scanning a laser beam modulated according to an image signal.

  In recent years, a laser projector that displays an image by scanning laser light has been proposed as an image display device that displays an image. Since the laser light has a single wavelength, the color purity is high, the coherence is high, and shaping is easy. For this reason, the laser projector has an advantage that good color reproducibility and a high-resolution image can be obtained. In order to display a bright image by a raster scan of a single laser beam, a very large amount of laser beam is required. In order to display an image with a single laser beam, it is necessary to make the modulation frequency for modulating the laser beam very high. In order to reduce such a burden caused by displaying an image with a single laser beam, a configuration for displaying an image using a plurality of laser beams has been proposed (for example, see Patent Document 1).

JP 2004-4818 A

  For example, when an image is displayed by interlace (interlace) scanning or progressive (sequential) scanning according to the NTSC signal, a vertical scanning frequency (refresh rate) of 60 Hz is employed. In the case of a CRT type display that displays an image by pulse light emission, the light emission period and the non-light emission period are easily recognized at a low refresh rate, and thus flicker that is flickering on the screen is likely to occur. Flicker is often generated when the refresh rate is approximately 60 hertz or less, depending on the screen size and display method. In addition, since human temporal sensitivity to light is particularly high in the peripheral visual field, the occurrence of flicker becomes more conspicuous as the screen becomes larger. Since continuing to observe the screen while feeling flicker may adversely affect the eyes, the refresh rate is preferably a value higher than 60 Hz. For example, according to a standard document of TCO (The Swedish Confederation of Professional Employees) 03, a refresh rate of 85 hertz or more is required as a refresh rate of a CRT type display.

  Even when gradation expression is performed by pulsed emission of laser light, it is desirable to increase the refresh rate in order to reduce flicker. In order to increase the refresh rate, it is necessary to scan the laser beam at high speed. However, since the scanning speed of the laser light is limited due to the characteristics of the scanning unit that scans the laser light, it is very difficult to scan the laser light at a speed higher than the limit. Further, when the laser beam is scanned at a high speed, since the scanning time of the beam light for each pixel is shortened, it is difficult to further increase the resolution and to express sufficient gradation. As described above, according to the conventional technique, there arises a problem that it is difficult to obtain a high-quality image by reducing flicker by increasing the refresh rate of the image and reducing the scanning speed of the beam light. The present invention has been made in view of the above-described problems, and is capable of displaying a high-quality image with less flicker by improving the refresh rate of the image and reducing the scanning speed of the beam light. It is an object of the present invention to provide a display device and a method for controlling an image display device.

  In order to solve the above-described problems and achieve the object, according to the present invention, there is provided an image display device for displaying an image using beam light modulated in accordance with an image signal, wherein at least two beams of the same color are displayed. A light source unit that supplies light, and a scanning unit that scans the beam light from the light source unit in a first direction and a second direction substantially orthogonal to the first direction in the irradiated region, and scanning The unit is driven such that the frequency of scanning the light beam in the first direction is higher than the frequency of scanning the light beam in the second direction, and the synchronization signal for the second direction included in the image signal If the frequency is p, it is possible to provide an image display device that scans m light beams in the second direction at a frequency higher than p of m and lower than or equal to p.

  Here, it is assumed that the light beams of the same color are light beams having substantially the same or similar wavelength regions. The frequency p is a refresh rate defined by NTSC or the like. In the case of using a plurality of light beams, a method of sharing a scanning region for each light beam and a method of sequentially scanning light beams in an irradiated region can be considered. When scanning a plurality of light beams, it is possible to improve the image refresh rate by setting the frequency at which the light beams are scanned in the second direction, which is the sub-scanning direction, to be higher than p for m. By increasing the image refresh rate, flicker can be reduced. Further, by setting the frequency for scanning the light beam to p or less, the speed at which the light beam is scanned can be made slower than when scanning a single light beam. Since the scanning speed of the light beam can be slowed, the scanning time of the light beam for each pixel can be extended. For this reason, it is possible to achieve higher resolution and sufficient gradation expression with a low modulation frequency. Thus, an image display device capable of displaying a high-quality image with less flicker can be obtained by improving the refresh rate of the image and reducing the scanning speed of the beam light.

  Further, according to a preferred aspect of the present invention, it is desirable that the irradiated area is divided into m scanning areas in the second direction and the beam light is scanned for each scanning area. When the beam light is scanned for each scanning area, the refresh rate of the image can be improved and the scanning speed of the beam light can be reduced by scanning the m light beams for each scanning area. Further, by reducing the scanning range of each light beam, the burden on the scanning unit can be reduced. By reducing the scanning range of each light beam, the scanning speed of the laser light can be further reduced.

  According to a preferred aspect of the present invention, it is desirable that m light beams are sequentially scanned at a predetermined interval in the irradiated region. By sequentially scanning the m light beams at a predetermined interval, it is possible to improve the refresh rate of the image and reduce the scanning speed of the light beams. Further, by sequentially scanning all the light beams in the irradiated region, it is possible to level individual differences for each light beam and obtain an image with a good light quantity distribution. Further, when the irradiated area is divided and scanned for each beam, the seams between the scanning areas are easily noticeable, but the seams can be eliminated.

  Moreover, as a preferable aspect of the present invention, it is desirable that the predetermined interval corresponds to approximately 1 / m of the length of the irradiated region in the second direction. By setting the distance between the light beams to such a length, the distance between the light beams when all m light beams are incident on the irradiated region can be maximized. By ensuring a large interval between the light beams, it is possible to reduce the bias of the light beams in the irradiated region and effectively increase the refresh rate of the image.

  As a preferred aspect of the present invention, it is desirable that the scanning unit includes a single scanning unit that scans a plurality of light beams in the first direction and the second direction. Accordingly, the beam light can be scanned in the first direction and the second direction with a simple configuration with a small number of parts.

  As a preferred aspect of the present invention, the scanning unit includes a first scanning unit that scans the beam light in the first direction, and a plurality of second scanning units that scan the beam light in the second direction. It is desirable. By providing a plurality of second scanning units that scan the light beam in the second direction, which is the sub-scanning direction, it is possible to appropriately set the interval between the light beams depending on the arrangement of the second scanning unit. Further, for example, when sequentially scanning light beams in the irradiated region, scanning of other light beams can be started sequentially without waiting for the end of scanning of one light beam. In this case, it is possible to further increase the refresh rate and effectively reduce flicker. Thus, by setting it as the structure provided with a 1st scanning part and a 2nd scanning part, a beam light can be scanned with a high freedom degree.

  Furthermore, according to the present invention, there is provided a method for controlling an image display device that displays an image using light beams modulated according to an image signal, the light supplying step supplying at least two light beams of the same color, A scanning step of scanning the light beam in a first direction in the irradiated region and a second direction substantially orthogonal to the first direction, and scanning the light beam in the first direction in the scanning step. Assuming that the frequency is higher than the frequency at which the beam light is scanned in the second direction and the frequency of the synchronization signal in the second direction included in the image signal is p, each of m light beams is m minutes. It is possible to provide a method for controlling an image display device, characterized in that scanning is performed in the second direction at a frequency higher than p and lower than p. When scanning a plurality of light beams, it is possible to improve the image refresh rate by setting the frequency at which the light beams are scanned in the second direction, which is the sub-scanning direction, to be higher than p for m. By increasing the image refresh rate, flicker can be reduced. Further, by setting the beam light scanning speed to be p or less, it is possible to lengthen the beam light scanning time for each pixel. For this reason, it is possible to achieve higher resolution and sufficient gradation expression with a low modulation frequency. Accordingly, it is possible to display a high-quality image with less flicker by improving the refresh rate of the image and reducing the scanning speed of the light beam.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  FIG. 1 shows a schematic configuration of an image display apparatus 100 according to Embodiment 1 of the present invention. The image display device 100 is a so-called rear projector that supplies laser light to one surface of the screen 110 and observes an image by observing light emitted from the other surface of the screen 110. The image display apparatus 100 displays an image by scanning laser light, which is a plurality of light beams, in the X direction that is the horizontal direction and the Y direction that is the vertical direction.

  FIG. 2 shows a schematic configuration of the laser apparatus 101. The laser device 101 includes an R light source 121 </ b> R that supplies red laser light (hereinafter referred to as “R light”) that is beam light, and green laser light (hereinafter referred to as “G light”) that is a beam light. Light source unit 121G for supplying G light and B light source unit 121B for supplying blue laser light (hereinafter referred to as “B light”) which is beam light.

  Each color light source unit 121R, 121G, and 121B supplies two laser beams modulated in accordance with the image signal. Each color light source unit 121R, 121G, 121B includes, for example, two laser diode elements that supply laser light. As the modulation according to the image signal, for example, pulse width modulation (hereinafter referred to as “PWM”) can be used. Each color light source unit 121R, 121G, and 121B supplies and stops the laser light from the laser diode element according to the image signal, and modulates the laser light supplied from the laser diode element by the light modulation element. Also good. As the light modulation element, for example, a liquid crystal element can be used.

  The laser device 101 is provided with two dichroic mirrors 124 and 125. The dichroic mirror 124 transmits R light and reflects G light. The dichroic mirror 125 transmits R light and G light and reflects B light. The R light from the R light source unit 121 </ b> R passes through the dichroic mirrors 124 and 125 and is then emitted from the laser device 101.

  The G light from the G light source 121G is reflected by the dichroic mirror 124, whereby the optical path is bent by approximately 90 degrees. The G light reflected by the dichroic mirror 124 passes through the dichroic mirror 125 and is then emitted from the laser device 101. The B light from the B light source 121B is reflected by the dichroic mirror 125, so that the optical path is bent by approximately 90 degrees. The B light reflected by the dichroic mirror 125 is emitted from the laser device 101. In this way, the laser device 101 supplies R light, G light, and B light modulated according to the image signal.

  Returning to FIG. 1, the laser light from the laser device 101 enters the scanning unit 200 after passing through the illumination optical system 102. The light from the scanning unit 200 enters the reflection unit 105 after passing through the projection optical system 103. The illumination optical system 102 and the projection optical system 103 project the laser light from the laser device 101 onto the screen 110. The reflection unit 105 reflects the laser light from the scanning unit 200 toward the screen 110. The housing 107 seals the space inside the housing 107.

  The screen 110 is provided on a predetermined surface of the housing 107. The screen 110 is a transmissive screen that transmits laser light modulated in accordance with an image signal. The light from the reflection unit 105 enters from the surface of the screen 110 on the inner side of the housing 107 and then exits from the surface on the viewer side. An observer observes the image by observing light emitted from the screen 110.

  FIG. 3 shows a schematic configuration of the scanning unit 200. The scanning unit 200 has a so-called double gimbal structure having a reflection mirror 202 and an outer frame portion 204 provided around the reflection mirror 202. The outer frame portion 204 is connected to a fixed portion (not shown) by a torsion spring 206 that is a rotating shaft. The outer frame portion 204 rotates around the torsion spring 206 using the twist of the torsion spring 206 and the restoration to the original state. The reflection mirror 202 is connected to the outer frame portion 204 by a torsion spring 207 that is a rotation axis substantially orthogonal to the torsion spring 206. The reflection mirror 202 reflects the laser light from the laser device 101. The reflection mirror 202 can be configured by forming a highly reflective member, for example, a metal thin film such as aluminum or silver.

  The reflection mirror 202 is displaced so that the laser beam is scanned in the Y direction (see FIG. 1) on the screen 110 when the outer frame portion 204 rotates about the torsion spring 206. The reflection mirror 202 rotates about the torsion spring 207 using the twist of the torsion spring 207 and the restoration to the original state. The reflection mirror 202 is displaced so as to scan the laser beam reflected by the reflection mirror 202 in the X direction by rotating about the torsion spring 207. Thus, the scanning unit 200 repeatedly scans the laser light from the laser device 101 in the X direction and the Y direction. In addition, the single scanning unit 200 can scan a plurality of laser beams in the X direction that is the first direction and the Y direction that is the second direction.

  FIG. 4 illustrates a configuration for driving the scanning unit 200. Assuming that the side on which the reflection mirror 202 reflects the laser light is the front side, the first electrodes 301 and 302 are spaces on the back side of the outer frame portion 204 and are provided at substantially symmetrical positions with respect to the torsion spring 206. Yes. When a voltage is applied to the first electrodes 301 and 302, a predetermined force corresponding to the potential difference, for example, an electrostatic force, is generated between the first electrodes 301 and 302 and the outer frame portion 204. The outer frame portion 204 rotates about the torsion spring 206 by alternately applying a voltage to the first electrodes 301 and 302.

  Specifically, the torsion spring 207 includes a first torsion spring 307 and a second torsion spring 308. A mirror-side electrode 305 is provided between the first torsion spring 307 and the second torsion spring 308. A second electrode 306 is provided in the space behind the mirror side electrode 305. When a voltage is applied to the second electrode 306, a predetermined force according to the potential difference, for example, an electrostatic force, is generated between the second electrode 306 and the mirror side electrode 305. When a voltage having the same phase is applied to any of the second electrodes 306, the reflection mirror 202 rotates about the torsion spring 207. The scanning unit 200 rotates the reflection mirror 202 in this way, thereby scanning the laser light in the two-dimensional direction. The scanning unit 200 can be created by, for example, MEMS (Micro Electro Mechanical Systems) technology.

  For example, during one frame period of the image, the scanning unit 200 reflects the laser beam so as to reciprocate the laser beam a plurality of times in the X direction that is the main scanning direction while scanning the laser beam once in the Y direction that is the sub scanning direction. 202 is displaced. Assuming that the X direction is the first direction and the Y direction is the second direction substantially orthogonal to the first direction, the scanning unit 200 has a frequency at which the laser beam is scanned in the first direction. Driven to be higher than the frequency of scanning light. In order to scan the laser beam in the X direction at high speed, it is desirable that the scanning unit 200 be configured to resonate the reflecting mirror 202 around the torsion spring 207. By causing the reflection mirror 202 to resonate, the amount of displacement of the reflection mirror 202 can be increased. By increasing the displacement amount of the reflection mirror 202, the scanning unit 200 can efficiently scan the laser beam with less energy. The reflection mirror 202 may be driven by an operation other than the resonance operation. The scanning unit 200 is not limited to the configuration driven by the electrostatic force corresponding to the potential difference. For example, the structure driven using the expansion-contraction force or electromagnetic force of a piezoelectric element may be sufficient.

  FIG. 5 illustrates the optical path of the laser light from the R light source unit 121R. Here, the configuration for supplying the laser light from the R light source unit 121R among the light source units for each color light will be described as a representative example, and illustrations of components unnecessary for the description are omitted. The R light source unit 121R includes two laser diode elements (LD) 501. Each laser diode element 501 supplies R light which is the same color beam light modulated independently. The same color light beams are light beams having substantially the same or similar wavelength regions.

  The illumination optical system 102 provided between the R light source unit 121 </ b> R and the scanning unit 200 can be configured by combining a convex lens 502 and a concave lens 503. The illumination optical system 102 adjusts the interval between the five laser beams by the convergence effect of the convex lens 502 and the diffusion effect of the concave lens 503. A projection optical system 103 between the scanning unit 200 and the screen 110 projects the laser light from the R light source unit 121 </ b> R onto the screen 110. By using the illumination optical system 102 and the projection optical system 103, a high-definition image can be displayed on the screen 110. Note that the two laser diode elements 501 are not limited to a configuration in which the two laser diode elements 501 are integrally disposed, and may be disposed apart from each other according to a desired interval of the laser light. The R light source unit 121R is not limited to the configuration in which the two laser diode elements 501 are provided, and may be configured to use a surface emitting semiconductor laser that supplies laser light from the two light emitting units.

  FIG. 6 illustrates scanning of laser light from the R light source unit 121R in the irradiated area AR0 of the screen 110. FIG. The laser beam L1 is scanned in the scanning area AR1, which is the upper half area of the irradiated area AR0. The laser beam L2 is scanned in the scanning area AR2, which is the lower half of the irradiated area AR0. As described above, the image display apparatus 100 divides the irradiated area AR0 into the two scanning areas AR1 and AR2 in the Y direction as the second direction, and scans the laser beams L1 and L2 for each of the scanning areas AR1 and AR2. . The laser beam L1 is modulated so as to display a portion of the scanning area AR1 in the image. The laser beam L2 is modulated so as to display a portion of the scanning area AR2 in the image.

  When scanning with a plurality of laser beams, the output per laser beam can be reduced in inverse proportion to the number of laser beams. In addition, it is possible to reduce the modulation frequency of the laser beam by sharing the scanning region with a plurality of laser beams. Here, it is assumed that the frequency of the vertical synchronization signal included in the image signal input to the image display apparatus 100 is p. The frequency p is a refresh rate and is defined by, for example, NTSC. The vertical synchronization signal is a synchronization signal in the second direction. The image display apparatus 100 scans the two laser beams L1 and L2 in the Y direction at a frequency that is higher than p of 2 minutes and lower than p.

  For example, if p = 60 hertz, the laser beams L1 and L2 are scanned in the Y direction at a frequency higher than 30 hertz and less than or equal to 60 hertz in the scanning areas AR1 and AR2, respectively. By scanning the two laser beams L1 and L2 in the Y direction at a frequency higher than 30 Hertz, the refresh rate can be improved as compared with scanning the single laser beam in the Y direction at 60 Hertz in the irradiated area AR0. Is possible. For example, when two laser beams L1 and L2 are scanned in the Y direction at 60 hertz, respectively, the refresh rate can be set to 120 hertz, which is twice that when a single laser beam is scanned at 60 hertz. . By increasing the image refresh rate, flicker can be reduced.

  In addition, by setting the frequency for scanning the laser beam to 60 hertz or less, the scanning speed of the laser beam can be made slower than when scanning a single laser beam. Since the scanning speed of the laser beam can be decreased, the scanning time of the laser beam for each pixel can be extended. For this reason, it is possible to achieve higher resolution and sufficient gradation expression with a low modulation frequency. As a result, it is possible to display a high-quality image with less flicker by improving the refresh rate of the image and reducing the scanning speed of the beam light.

  In addition, the scanning range of each of the laser beams L1 and L2 can be reduced to one-half that of the irradiated area AR0 as compared with a case where a single laser beam is scanned in the irradiated area AR0. As a result, the swing angle of the reflection mirror 202 (see FIG. 3) can be reduced, and the burden on the scanning unit 200 can be reduced. Since the scanning range of each of the laser beams L1 and L2 can be reduced, the scanning speed of the laser beam can be further reduced. Furthermore, in this embodiment, by using the single scanning unit 200, it is possible to scan a plurality of laser beams in the X direction and the Y direction with a simple configuration with a small number of parts.

  Note that the image display device 100 is not limited to the configuration that scans two laser beams for each color, and may be configured to scan three or more laser beams. When scanning m light beams, the irradiated area AR0 can be divided into m scanning areas in the Y direction, and laser light can be scanned for each scanning area. Further, by scanning m laser beams at a frequency higher than p of m and less than or equal to p, an image refresh rate can be improved and a beam scanning speed can be reduced. Furthermore, the image display apparatus 100 may be configured to parallel a plurality of laser beams in the X direction that is the main scanning direction and the Y direction that is the sub scanning direction.

  FIG. 7 shows a block configuration for controlling the image display apparatus 100. The image signal input unit 711 performs characteristic correction and amplification of the image signal input from the input terminal. For example, the image signal input unit 711 converts an analog image signal into a digital light source modulation intensity signal and outputs it. In addition, the image signal input unit 711 may output a digital image signal as a digital light source modulation intensity signal. The synchronization / image separation unit 712 separates the signal from the image signal input unit 711 into an image information signal, a vertical synchronization signal, and a horizontal synchronization signal for each of R light, G light, and B light, and outputs them to the control unit 713. To do. The image processing unit 721 in the control unit 713 divides the image information into information for each frame and outputs the information to the frame memory 714. The frame memory 714 stores the image information signal from the image processing unit 721 in units of frames.

  The control unit 713 converts the vertical synchronization signal from the synchronization / image separation unit 712 so that the laser beam is scanned at a frequency higher than p of m and equal to or lower than p. For example, a frame converter can be used for the frequency conversion. As a result, a drive signal having a desired frequency can be generated. The control unit 713 generates a horizontal synchronization signal based on the vertical synchronization signal converted by the control unit 713. The scanning control unit 723 generates a drive signal for driving the scanning unit 200 based on the vertical synchronization signal and the horizontal synchronization signal converted by the control unit 713. The scan driver 715 drives the scanner 200 in response to a drive signal from the controller 713. In the scanning process, with this configuration, the laser beam is scanned in the X direction and the Y direction in the irradiated region.

  The horizontal angle sensor 716 detects the swing angle of the reflection mirror 202 (see FIG. 3) that scans the laser beam in the X direction on the screen 110. The vertical angle sensor 717 detects the swing angle of the reflection mirror 202 that causes the screen 110 to scan the laser beam in the Y direction. The signal processing unit 718 generates a frame start signal F_Sync from the displacement of the vertical angle sensor 717 and a line start signal L_Sync from the displacement of the horizontal angle sensor 716, and outputs them to the control unit 713.

  The control unit 713 generates a pixel timing clock based on the frame start signal F_Sync, the linear velocity calculated from the line start signal L_Sync, and the vertical synchronization signal and horizontal synchronization signal converted by the control unit 713. The pixel timing clock is a signal for knowing the timing at which the laser beam passes on each pixel, and is for causing the laser beam modulated in accordance with the image signal to enter an accurate position.

  The R light source driving unit 732R drives the R light source unit 121R based on the light source driving pulse signal from the light source control unit 722. The R light source driving unit 732R controls the two LDs of the R light source unit 121R according to the light source driving pulse signal. The G light source driving unit 732G also drives the G light source unit 121G in the same manner as the R light source driving unit 732R. Similarly to the R light source driving unit 732R, the B light source driving unit 732B drives the B light source unit 121B. In the beam light supplying step, a plurality of laser beams are supplied with this configuration.

  FIG. 8 explains in detail a configuration for supplying laser light modulated in accordance with an image signal. The image information signal stored in the frame memory 714 from the image processing unit 721 is divided for each of the scanning areas AR1 and AR2 (see FIG. 6) and input to the light source control unit 722. Through the frame memory 714, it is possible to extract an image information signal for each arbitrary scanning area. The light source controller 722 generates a light source driving pulse signal having a pulse width corresponding to the image information signal for each of the laser beams L1 and L2. The light source drive pulse signal for each of the laser beams L1 and L2 is input to the laser diode driver (LDD) 801 of the R light source driver 732R. Each laser diode driver 801 drives the laser diode element 501.

  FIG. 9 illustrates an image display apparatus according to Embodiment 2 of the present invention, and illustrates scanning of laser light from the R light source unit in the irradiated area AR0 of the screen. The image display apparatus of the present embodiment is characterized in that two laser beams are sequentially scanned at a predetermined interval d in the irradiated area AR0. The same parts as those of the image display apparatus 100 of the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  In the image display apparatus of the present embodiment, both the laser beam L1 and the laser beam L2 scan the entire irradiated area AR0. The distance d between the laser light L1 and the laser light L2 in the irradiated area AR0 corresponds to approximately one half of the length h of the irradiated area AR0 in the Y direction. FIG. 9 shows a state in which the laser beam L1 and the laser beam L2 are scanned simultaneously in the irradiated area AR0.

  FIG. 10 illustrates scanning of the laser light L1 and the laser light L2. Here, a case where the laser beam L1 and the laser beam L2 are scanned by the same configuration as that described with reference to FIG. 5 in the first embodiment will be described. Since the single scanning unit 200 is used, the positional relationship between the laser light L1 and the laser light L2 is always constant. As shown in FIG. 10, first, the lower laser beam L2 of the two laser beams starts scanning from the upper left of the irradiated area AR0. At this time, since the laser light L1 is emitted toward the outside of the irradiated area AR0, the supply of the laser light L1 is stopped. In FIG. 10, the supply of the laser light L1 is stopped by adding a black circle.

  When the scanning of the laser beam L2 in the Y direction reaches the vicinity of the center of the irradiated area AR0, the scanning of the laser beam L1 also starts from the upper left part of the irradiated area AR0. Thereafter, the laser beam L1 and the laser beam L2 simultaneously scan the irradiated area AR0 until the laser beam L2 reaches the lower outer edge of the irradiated area AR0. Then, the supply of the laser light L2 is stopped in a state where the laser light L2 is incident on the outside of the irradiated area AR0, and only the laser light L1 is scanned to the lower outer edge of the irradiated area AR0. The scanning unit 200 is driven so as to repeat such scanning of the laser beams L1 and L2. In this way, the image display device sequentially scans the entire irradiated area AR0 with the two laser beams L1 and L2 at a predetermined interval d.

  By sequentially scanning the plurality of laser beams L1 and L2 at a predetermined interval d, it is possible to improve the refresh rate of the image and reduce the scanning speed of the laser beam as in the first embodiment. As a result, as in the first embodiment, it is possible to display a high-quality image with less flicker by improving the refresh rate of the image and reducing the scanning speed of the light beam. Further, by sequentially scanning all the laser beams in the irradiated area AR0, it is possible to level the individual difference for each laser beam and obtain an image with a good light amount distribution. Further, when the irradiated region is divided and scanned for each laser beam, the joint between the scanning regions becomes more conspicuous, but such a joint can be eliminated.

  By setting the interval d between the laser beams L1 and L2 to be approximately one-half the length h of the irradiated area AR0, it is possible to ensure a large interval between the laser beams L1 and L2. By ensuring a large distance between the laser beams L1 and L2, it is possible to reduce the bias of the laser beams L1 and L2 in the irradiated area AR0 and effectively increase the refresh rate of the image. Thereby, the refresh rate of the image can be effectively increased. Also in this embodiment, the image display device is not limited to the configuration in which two laser beams are scanned for each color, and may be configured to scan in three or more laser beams. When scanning m light beams, the predetermined interval d can be configured to correspond to approximately 1 / m of the length h in the Y direction of the irradiated area AR0.

  FIG. 11 illustrates in detail a configuration for supplying laser light modulated in accordance with an image signal. The image information signal for one of the two laser beams L1 and L2 that scans the irradiated area AR0 first is input from the image processing unit 721 directly to the light source control unit 722 without passing through the frame memory 714. The image information signal for the other laser beam L 1 is stored in the frame memory 714 and then input to the light source controller 722. In this way, an image can be displayed by scanning each pixel with the laser beam L1 while being delayed by a predetermined time with respect to the laser beam L2.

  Further, as compared with the case where the image information signals for both the laser beams L1 and L2 are stored, the amount of data stored in the frame memory 714 can be reduced, and the frame memory 714 can be reduced in capacity and cost. Become. In the present embodiment, as in the first embodiment, the image information signal for the laser beam L1 and the image information signal for the laser beam L2 are both stored in the frame memory 714 and then output to the light source controller 722. Also good.

  The image information signal for modulating the laser beam L1 may be generated by calculating a motion vector from the image information signal for modulating the laser beam L2. The calculation of the motion vector can be performed by the image processing unit 721, for example. By the motion vector calculation, an intermediate image by the laser beam L1 can be displayed using the image signal input to the image display device. Thereby, flicker can be further reduced. Further, the intermediate image by the laser light L1 may be generated by calculating an average value of image information signals for adjacent frames.

  In the present embodiment and the first embodiment, the image display device is not limited to the configuration in which the laser beam is scanned in the X direction and the Y direction by the single reflection mirror 202 provided in the scanning unit 200. A configuration using a reflection mirror that is a first scanning unit that scans laser light in the X direction that is the first direction, and a reflection mirror that is a second scanning unit that scans the laser light in the Y direction that is the second direction. It is also good. Even when the first scanning unit and the second scanning unit are used, the laser beam can be scanned in the X direction and the Y direction.

  FIG. 12 shows a configuration in which two second reflection mirrors 1202 that are two second scanning units are used for the first reflection mirror 1201 that is a single first scanning unit. In the configuration shown in FIG. 12, two units each including a laser diode element 501, an illumination optical system 102, and a second reflection mirror 1202 are provided. Laser light from the two second reflection mirrors 1202 is scanned in the X direction by a single first reflection mirror 1201.

  When two second reflection mirrors 1202 are provided, the interval d between the laser beams can be set as appropriate depending on the arrangement of the second reflection mirrors 1202. It is also possible to set the number of scans for each second reflection mirror 1202 as appropriate. Further, the two second reflection mirrors 1202 can be driven at different timings. For this reason, as shown in FIG. 13, after the scanning of one laser beam L2 reaches the lower outer edge of the irradiated area AR0, the other laser beam L1 reaches the lower outer edge of the irradiated area AR0. It is also possible to start the next scanning of the laser beam L2 without waiting for the above. With the configuration including the plurality of second reflection mirrors 1202, the refresh rate can be further increased and flicker can be effectively reduced. With the configuration including the first scanning unit and the second scanning unit, the laser beam can be scanned with such a high degree of freedom.

  In this case, the distance d between the laser beams L1 and L2 can be maximized by setting the distance d between the laser beams L1 and L2 to approximately one half of the length h of the irradiated area AR0. . By ensuring a large interval between the laser beams L1 and L2, it is possible to reduce the bias of the laser beams L1 and L2 in the irradiated area AR0 and effectively increase the refresh rate of the image.

  When two second reflection mirrors 1202 are used, scanning of the laser beam L2 for the next frame starts before the laser beam L1 reaches the lower outer edge of the irradiated area AR0. In this way, even when the screen is switched before the laser beam L1 scans the entire surface of the irradiated area AR0, the laser beams L1 and L2 can be used by eliminating the bias in the positions of the laser beams L1 and L2 in the irradiated area AR0. It is possible to provide the viewer with an averaged image.

  The number of the second reflection mirrors 1202 is not limited to two, and may be three or more depending on the number of laser beams. Further, the first scanning unit and the second scanning unit are not limited to the case of using a reflecting mirror, and for example, a polygon mirror that rotates a rotating body including a plurality of mirror pieces may be used. Furthermore, a configuration in which a plurality of scanning units 200 described with reference to FIG. 3 are used may be employed. For example, when a plurality of scanning units are provided according to the number of laser beams, the laser beams can be scanned with a high degree of freedom.

  FIG. 14 shows a schematic configuration of an image display apparatus 1700 according to the third embodiment of the present invention. The image display device 1700 is a so-called front projection projector that supplies laser light to a screen 1705 provided on the viewer side and observes an image by observing light reflected by the screen 1705. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. Laser light from the scanning unit 200 passes through the projection optical system 103 and then enters the screen 1705. Also in this embodiment, it is possible to display a high-quality image with less flicker by improving the refresh rate of the image and reducing the scanning speed of the laser beam.

  In the above-described embodiments, each color light source unit uses a laser diode element. However, the present invention is not limited to this as long as it can supply beam-like light. For example, each color light source unit may be configured to use a liquid laser or a gas laser in addition to a solid-state light emitting element such as a solid-state laser and a light-emitting diode element (LED).

  As described above, the image display device according to the present invention is suitable for displaying an image using a plurality of light beams.

1 is a diagram illustrating a schematic configuration of an image display apparatus according to Embodiment 1 of the present invention. The figure which shows schematic structure of a laser apparatus. The figure which shows schematic structure of a scanning part. The figure explaining the structure for driving a scanning part. The figure explaining the optical path of the laser beam from the light source part for R light. FIG. 6 illustrates scanning of laser light in an irradiated area. The figure which shows the block structure for controlling an image display apparatus. The figure which shows the structure for supplying the laser beam modulated according to the image signal. FIG. 6 is a diagram illustrating an image display device according to a second embodiment of the invention. FIG. 6 illustrates scanning of laser light. The figure which shows the structure for supplying the laser beam modulated according to the image signal. The figure which shows the structure using an independent 1st scanning part and two 2nd scanning parts. FIG. 6 illustrates scanning of laser light. FIG. 9 is a diagram illustrating a schematic configuration of an image display device according to a third embodiment of the invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 Image display apparatus, 101 Laser apparatus, 102 Illumination optical system, 103 Projection optical system, 105 Reflection part, 107 Housing | casing, 110 Screen, 200 scanning part, 121RR Light source part for 121R G light source part, 121B B Light source section for light, 124, 125 Dichroic mirror, 202 Reflective mirror, 204 Outer frame section, 206 Torsion spring, 207 Torsion spring, 301, 302 First electrode, 305 Mirror side electrode, 306 Second electrode, 307 First Torsion spring, 308 second torsion spring, 501 laser diode element, 502 convex lens, 503 concave lens, AR0 irradiated region, AR1, AR2 scanning region, 711 image signal input unit, 712 synchronization / image separation unit, 713 control unit, 714 frame memory, 715 scans Moving unit, 716 horizontal angle sensor, 717 vertical angle sensor, 718 signal processing unit, 721 image processing unit, 722 light source control unit, 723 scanning control unit, 732R R light source driving unit, 732G G light source driving unit, 732B B light source driving unit 801 Laser diode driver 1201 First reflection mirror 1202 Second reflection mirror 1700 Image display device 1705 Screen

Claims (7)

An image display device that displays an image using beam light modulated according to an image signal,
A light source unit that supplies at least two beams of the same color;
A scanning unit that scans the beam light from the light source unit in a first direction in a region to be irradiated and a second direction substantially orthogonal to the first direction;
The scanning unit is driven such that a frequency at which the light beam is scanned in the first direction is higher than a frequency at which the light beam is scanned in the second direction;
Assuming that the frequency of the synchronization signal in the second direction included in the image signal is p, m beams of light are respectively in the second direction at a frequency higher than p for m and equal to or less than p. An image display device characterized by being scanned.   The image display apparatus according to claim 1, wherein the irradiated area is divided into m scanning areas in the second direction, and the beam light is scanned for each of the scanning areas.   The image display apparatus according to claim 1, wherein the m light beams are sequentially scanned at a predetermined interval in the irradiated region.   The image display apparatus according to claim 3, wherein the predetermined interval corresponds to approximately 1 / m of a length of the irradiated region in the second direction.   The image according to claim 1, wherein the scanning unit includes a single scanning unit that scans the plurality of light beams in the first direction and the second direction. Display device.   The scanning unit includes a first scanning unit that scans the light beam in the first direction, and a plurality of second scanning units that scan the light beam in the second direction. The image display apparatus as described in any one of Claims 1-4. A control method for an image display device that displays an image using a light beam modulated in accordance with an image signal,
A light supply step for supplying at least two beams of the same color;
A scanning step of scanning the light beam in a first direction in a region to be irradiated and a second direction substantially orthogonal to the first direction,
In the scanning step, a frequency at which the light beam is scanned in the first direction is higher than a frequency at which the light beam is scanned in the second direction.
Assuming that the frequency of the synchronization signal in the second direction included in the image signal is p, m beams of light are respectively in the second direction at a frequency higher than p of m and equal to or lower than p. A method for controlling an image display device, characterized by:

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