JP2006243225A - Optical scanner and image display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical scanner in which light is efficiently and stably scanned with a constant scanning width and to provide an image display apparatus which stably displays a high quality picture by using the optical scanner. <P>SOLUTION: The optical scanner has: a main light source part 101 which supplies a light beam L1; and a reflection mirror 104 which reflects the light L1 from the main light source part 101 and oscillates; and a light detection pat 403 which detects light for detecting the displacement of the reflection mirror 104. The reflection mirror 104 is driven on the basis of a signal from the light detection part 403. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical scanning device and an image display device, and more particularly to a technique of an optical scanning device used for an image display device.

  In recent years, an image display apparatus that displays an image by scanning beam-like light has been proposed. The image display device uses an optical scanning device that scans light by vibrating a reflecting mirror that reflects light. In order to display an image on a predetermined surface using a planar reflection mirror, the optical scanning device needs to reciprocate the reflection mirror within an angle range in which the reflected light is incident on the predetermined surface. Since it is desirable that the optical system used in the image display apparatus is compact, it is desirable that the reflection mirror used in the optical scanning apparatus can be driven with a small configuration and a large rotation angle. In order to obtain a rotation angle with a small driving force, it has been proposed to drive the reflecting mirror at a resonance frequency unique to the reflecting mirror. The reflection mirror can be driven efficiently with less energy by driving at the resonance frequency.

  The resonance frequency of the reflection mirror is determined according to the Young's modulus of the members constituting the reflection mirror. Since the Young's modulus changes according to the temperature change, the resonance frequency of the reflection mirror depends on the heat accumulated in the optical scanning device as a part of the laser beam is absorbed by the reflection mirror, the ambient temperature, and the reflection mirror. Is easily changed by the influence of heat or the like generated by driving. When the resonance frequency of the reflecting mirror changes, the driving of the reflecting mirror tends to become unstable, for example, the swing angle is remarkably reduced even if the reflecting mirror is always driven at a substantially constant cycle. Therefore, in order to stably resonate the reflection mirror, a method of driving the reflection mirror by positively feeding back a signal obtained by detecting the displacement of the reflection mirror is considered. A technique for driving the reflection mirror by positively feeding back a signal obtained by detecting the displacement of the reflection mirror is proposed in, for example, Patent Document 1.

JP 2002-78368 A

  In the technique proposed in Patent Document 1, a detection coil as a detection means is provided on the reflection mirror. An electromotive force corresponding to the angular velocity of the reflection mirror is generated in the detection coil due to the displacement of the reflection mirror. Such electromotive force can detect the displacement of the reflecting mirror. In this case, an electromotive force having a phase opposite to the voltage for driving the reflection mirror is generated in the detection coil, and thus the vibration of the reflection mirror may be hindered by a force in a direction opposite to the force for driving the reflection mirror. Thus, when the vibration for the reflection mirror is hindered by the configuration for detecting the displacement of the reflection mirror, it is difficult to stably resonate the reflection mirror. In addition, a configuration using a piezoelectric element is considered as a configuration for detecting the displacement of the reflection mirror. For example, when a piezoelectric element is attached to a torsion spring that rotates the reflecting mirror, the displacement of the reflecting mirror can be detected from a change in the resistance value of the piezoelectric element. In this case, it is difficult to accurately detect the displacement of the reflection mirror even though it is possible to prevent the generation of a force that prevents the reflection mirror from vibrating. As described above, the conventional technique has a problem that it is difficult to stably resonate the reflecting mirror. The present invention has been made in view of the above-described problems. An optical scanning device capable of efficiently and stably scanning light with the same scanning width and a high quality by using the optical scanning device. An object of the present invention is to provide an image display device capable of stably displaying a stable image.

  In order to solve the above-described problems and achieve the object, according to the present invention, a main light source unit that supplies beam-shaped light, a reflection mirror that reflects and vibrates light from the main light source unit, and a reflection mirror And a light detection unit that detects light for detecting the displacement of the light source, and the reflection mirror is driven based on a signal from the light detection unit. .

  The optical scanning device of the present invention detects the displacement of the reflecting mirror using light. By adopting a configuration in which the displacement of the reflection mirror is detected using light, it is possible to avoid the occurrence of a force that hinders the vibration of the reflection mirror in the reflection mirror. Moreover, it becomes possible to detect the displacement of a reflective mirror correctly by setting it as the structure which detects light by a photon detection part. By positively feeding back the signal obtained by detecting the displacement of the reflecting mirror, the reflecting mirror can be stably resonated. As a result, an optical scanning device that can scan light efficiently and stably with the same scanning width can be obtained.

  According to a preferred aspect of the present invention, it is desirable to have a detection light source unit that supplies light for detecting the displacement of the reflection mirror. Thereby, the displacement of the reflection mirror can be detected in the light detection unit.

  Moreover, according to the preferable aspect of this invention, it is desirable for the light source part for a detection to supply the light of the other wavelength range different from the wavelength range of visible light. By making the light for detecting the displacement of the reflecting mirror light other than visible light, even if the detection light travels in the direction of the observer, it can be prevented from being recognized by the observer. Thereby, the situation where the contrast of the light from the main light source part falls can be avoided.

  As a preferred embodiment of the present invention, it is desirable that the detection light source unit supplies infrared light. A light source that supplies infrared light is less expensive than a light source that supplies ultraviolet light, and has the advantage of being easy to handle. Thereby, the optical scanning device can be configured to be inexpensive and easy to handle.

  In a preferred aspect of the present invention, the reflection mirror includes a first reflection mirror that scans light from the main light source unit in the first direction, and a first mirror that substantially orthogonally intersects the light from the main light source unit with the first direction. It is desirable that the light detection unit and the detection light source unit be provided for at least one of the first reflection mirror and the second reflection mirror. With the configuration in which the light detection unit and the detection light source unit are provided in units of reflection mirrors, the light detection unit can detect the amplitude of light that is constantly scanned for each cycle in which the reflection mirror vibrates. Therefore, it is possible to detect the amplitude with high frequency and accurately control at least one of the first reflecting mirror and the second reflecting mirror. Thereby, light can be accurately scanned with the same scanning width in at least one of the first direction and the second direction.

  As a preferred aspect of the present invention, it is desirable that the main light source unit supplies light for detecting the displacement of the reflecting mirror. By supplying light for detecting the displacement of the reflecting mirror from the main light source unit, a new light source unit for supplying detection light becomes unnecessary. As a result, the optical scanning device can have a simple configuration.

  Furthermore, according to the present invention, there is provided an image display device that displays an image by light from an optical scanning device, the optical scanning device including a main light source unit that supplies beam-shaped light, and light from the main light source unit. A reflection mirror that vibrates and vibrates; and a light detection unit that detects light for detecting displacement of the reflection mirror, wherein the reflection mirror is driven based on a signal from the light detection unit. An image display device can be provided.

  By adopting a configuration in which the displacement of the reflection mirror is detected using light, it is possible to avoid the occurrence of a force that prevents the reflection mirror from vibrating on the reflection mirror. Moreover, it becomes possible to detect the displacement of a reflective mirror correctly by setting it as the structure which detects light by a photon detection part. By positively feeding back the signal obtained by detecting the displacement of the reflecting mirror, the reflecting mirror can be stably resonated. For this reason, the optical scanning device can scan light efficiently and stably with the same scanning width. By using the optical scanning device, an image display device capable of stably displaying a high quality image can be obtained.

  Moreover, as a preferable aspect of the present invention, the main light source unit supplies light for detecting the displacement of the reflection mirror to the peripheral part of the scanning region that scans the light from the main light source unit. It is desirable to be provided at the periphery. Thereby, the displacement of the reflection mirror can be detected using the light supplied from the main light source unit.

  Moreover, as a preferable aspect of the present invention, it is desirable to have a light absorbing portion that is provided in a portion of the peripheral portion other than the portion where the light detecting portion is provided and absorbs light for detecting the displacement of the reflecting mirror. By absorbing the light for detecting the displacement of the reflection mirror by the light absorption unit, only the light corresponding to the image signal can be advanced toward the observer. Thereby, a reduction in contrast of the image can be reduced.

  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 optical scanning device 120 provided in the image display device 100 scans the laser light by vibrating the reflection mirror 104. The image display device 100 displays an image on the screen 110 which is a predetermined surface by the light from the optical scanning device 120.

  The main light source unit 101 supplies red laser light, green laser light, and blue laser light, which are beam-shaped lights, in accordance with image signals, respectively. As the main light source unit 101, a semiconductor laser provided with a modulation unit for modulating laser light or a solid-state laser can be used. As the modulation according to the image signal, either amplitude modulation or pulse width modulation may be used. Note that a shaping optical system for shaping the laser light into a beam shape having a diameter of 0.5 mm, for example, may be provided on the emission side of the main light source unit 101.

  The reflection mirror 104 reflects the laser beam from the main light source unit 101 and vibrates, thereby scanning the laser beam in a two-dimensional direction. The laser light incident on the reflection mirror 104 is reflected in the direction of the reflection unit 105. The laser beam reflected by the reflection mirror 104 enters the reflection unit 105. The reflection unit 105 is provided on the inner surface of the housing 107 at a position facing the screen 110. The laser light incident on the reflection unit 105 travels in the direction of 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 from the optical scanning device 120 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. The observer observes the image by observing the light emitted from the screen 110.

  FIG. 2 shows a planar configuration of the reflection mirror 104. Here, it is assumed that the reflection mirror 104 scans the laser beam in the one-dimensional direction out of the two-dimensional directions and is illustrated and described. The reflection mirror 104 can be configured by forming a highly reflective member, for example, a metal thin film such as aluminum or silver. The reflection mirror 104 is connected to the fixed portion 201 by a torsion spring 202 that is a rotation shaft. The torsion spring 202 rotates the reflection mirror 104 toward the front side and the other side of the page. The reflection mirror 104 is not limited to a square shape, and may be a circular shape, for example.

  The reflection mirror 104 is driven using an electrostatic force acting between comb-shaped electrodes. The torsion spring 202 is provided with a movable electrode 204. The movable electrode 204 is a comb-shaped electrode that moves with the rotation of the torsion spring 202. A fixed side electrode 205 is provided in the vicinity of the movable side electrode 204. The fixed side electrode 205 is a comb-shaped electrode provided so as to be always fixed regardless of the rotation of the torsion spring 202. The movable side electrode 204 and the fixed side electrode 205 are arranged so that the comb-tooth portions are engaged with each other.

  FIG. 3 illustrates driving of the reflection mirror 104 by the movable side electrode 204 and the fixed side electrode 205. The comb-tooth portion of the movable-side electrode 204 and the comb-tooth portion of the fixed-side electrode 205 are viewed from the side. The configuration is shown. Before applying a voltage between the movable side electrode 204 and the fixed side electrode 205, the comb-tooth portion of the movable-side electrode 204 and the comb-tooth portion of the fixed-side electrode 205 are in a position shifted vertically from each other. When a voltage is applied between the movable side electrode 204 and the fixed side electrode 205 from this state, the movable side electrode 204 and the fixed side are interposed between the comb tooth portion of the movable side electrode 204 and the comb tooth portion of the fixed side electrode 205. In accordance with the potential difference with the electrode 205, electrostatic forces that attract each other are generated.

  The movable part side electrode 204 operates by the resultant force of the electrostatic force and the restoring force of the torsion spring 202. When the electrostatic force between the comb tooth portion of the movable side electrode 204 and the comb tooth portion of the fixed side electrode 205 becomes larger than the force necessary to twist the torsion spring 202, the movable side electrode 204 moves downward as indicated by an arrow. Move to. The reflection mirror 104 rotates about the torsion spring 202 until the electrostatic force and the restoring force of the torsion spring 202 are balanced by the electrostatic force according to the potential difference between the movable electrode 204 and the fixed electrode 205.

  Next, when the voltage application between the movable side electrode 204 and the fixed side electrode 205 is stopped, the electrostatic force generated between the comb tooth portion of the movable side electrode 204 and the comb tooth portion of the fixed side electrode 205 is Disappear. When the electrostatic force disappears, the movable-side electrode 204 moves in a direction to return to the original position by the restoring force of the torsion spring 202. When the movable electrode 204 moves in the direction returning to the original position, the reflection mirror 104 rotates in the opposite direction. While the generation of the electrostatic force is stopped, the reflection mirror 104 rotates around the torsion spring 202 by the restoring force of the torsion spring 202. The reflection mirror 104 reciprocally rotates by repeatedly applying a voltage between the movable side electrode 204 and the fixed side electrode 205 and stopping the voltage application.

  The movable side electrode 204 and the fixed side electrode 205 are not limited to being provided on one side with respect to the torsion spring 202, and may be provided on both sides of the torsion spring 202. In this case, the reflection mirror 104 can be vibrated by alternately applying a voltage to the right electrode and the left electrode with respect to the torsion spring 202. The reflection mirror 104 and the components for driving the reflection mirror 104 can be created by, for example, MEMS (Micro Electro Mechanical Systems) technology.

  The reflection mirror 104 has a unique resonance frequency determined by the mass and shape of the reflection mirror 104 itself, the spring constant of the torsion spring 202, and the like. The reflection mirror 104 can increase the amount of displacement by being driven at the resonance frequency. In particular, since it is desirable that the optical system used in the image display apparatus 100 be compact, the reflection mirror 104 is required to be able to be driven with a small configuration and a large rotation angle. In order to efficiently scan the laser beam with less energy, it is desirable to drive the reflection mirror 104 at the resonance frequency.

  The reflection mirror 104 is not limited to be driven by using an electrostatic force acting between comb-shaped electrodes, but may be driven by another driving method using an electrostatic force. Furthermore, the reflection mirror 104 is not limited to the configuration driven by the electrostatic force corresponding to the potential difference. For example, the reflection mirror 104 may be configured to be driven using electromagnetic force or driven using the expansion / contraction force of a piezoelectric element. When the electromagnetic force is used, for example, the reflection mirror 104 can be driven by generating an electromagnetic force between the reflection mirror 104 and the permanent magnet according to the current.

  FIG. 4 illustrates a configuration for detecting the displacement of the reflection mirror 104. Assuming that the surface of the reflection mirror 104 that reflects the laser light L1 from the main light source unit 101 is the front surface, the light source unit 401 for detection and the light detection unit 403 are provided in the space to which the back surface of the reflection mirror 104 is directed. . The detection light source unit 401 supplies light L2 for detecting the displacement of the reflection mirror 104. The light detection unit 403 detects light for detecting the displacement of the reflection mirror 104.

  As the light source 401 for detection, for example, an infrared laser diode that supplies infrared light can be used. By making the light L2 for detecting the displacement of the reflection mirror 104 into infrared light that is light other than visible light, even if the light L2 travels in the direction of the observer, the light L2 is recognized by the observer. Can be avoided. Thereby, the situation where the contrast of the light L1 from the main light source part falls can be avoided. In addition, a light source that supplies infrared light is less expensive than a light source that supplies ultraviolet light, and has the advantage of being easy to handle. Thereby, the optical scanning device 120 can be configured to be inexpensive and easy to handle.

  The light source 401 for detection is not limited to the case where an infrared laser diode is used as long as it supplies light in a wavelength region other than the wavelength region of visible light. In addition, even if the detection light L2 from the detection light source unit 401 is scattered, the detection light source unit 401 is configured to supply visible light in a case where the light is not emitted from the screen 110 (see FIG. 1). It is also good.

  The detection light source unit 401 supplies light L2 to the back surface of the reflection mirror 104. The reflection mirror 104 reflects the light L2 from the light source 401 for detection on the back surface in the same manner as the laser light L1 is scanned by reflecting the laser light L1 from the main light source 101 on the surface. The light L2 is scanned. When the light L2 scans on the virtual plane S so as to form a linear scanning locus SC, the light detection unit 403 is provided on the scanning locus SC. Note that a highly reflective member may be formed on at least a portion of the back surface of the reflecting mirror 104 where the light L2 is incident, similar to the front surface. By adopting a configuration in which the light L2 is reflected by a highly reflective member, a signal having a high S / N ratio can be obtained by the light detection unit 403.

  FIG. 5 illustrates a position where the light detection unit 403 is provided. The reflection mirror 104 oscillates with substantially the same swing angle about the torsion spring 202, so that the detection light L2 scans with the substantially same scanning width from the center point on the scanning locus SC. The light detection unit 403 is provided at a position away from the center point by a distance d. The position where the light detection unit 403 is provided is a position closer to the center point than the position where the light L2 returns when the reflection mirror 104 vibrates so that the laser light L1 scans with an ideal scanning width. The center point of the scanning locus SC is the incident position of the light L2 on the virtual surface S when the deflection angle of the reflection mirror 104 is 0 degree. As the light detection unit 403, for example, a phototransistor or a photocell can be used.

  Returning to FIG. 4, the optical scanning device 120 is not limited to the configuration in which the detection light source unit 401 and the light detection unit 403 are provided in the space where the back surface of the reflection mirror 104 is directed. In the detection light source unit 401 and the light detection unit 403, at least the detection light L2 reflected by the reflection mirror 104 travels in a direction different from the light L1 from the main light source unit 101 reflected by the reflection mirror 104. What is necessary is just to be provided in the position. For example, the detection light source unit 401 and the light detection unit 403 may be provided in a space to which the surface of the reflection mirror 104 is directed, and the detection light L <b> 2 may be reflected by the surface of the reflection mirror 104. In this case, since it is not necessary to form a highly reflective member on the back surface of the reflecting mirror 104, the reflecting mirror 104 can be further simplified.

  Furthermore, the optical scanning device 120 is not limited to the configuration that detects the detection light L <b> 2 reflected by the reflection mirror 104. For example, the detection light source unit 401 may be provided at a position other than the position on the rotation axis in the reflection mirror 104, and the detection light L <b> 2 from the detection light source unit 401 may be directly incident on the virtual surface S. Also in this case, the detection light L2 can be scanned on the virtual surface S.

  FIG. 6 shows a block configuration for driving the reflection mirror 104. The control unit 601 generates a drive signal for driving the reflection mirror 104 and outputs the drive signal to the drive unit 602. The drive unit 602 drives the reflection mirror 104 using a voltage corresponding to the drive signal from the control unit 601. The light detection unit 403 detects light for detecting the displacement of the reflection mirror 104 and outputs the detection result to the calculation unit 604.

  FIGS. 7A and 7B illustrate the scanning width of the detection light L2 and a signal representing the displacement of the reflection mirror 104. FIGS. A scanning locus SC <b> 1 illustrated in FIG. 7A is a case where the detection light L <b> 2 scans with a scan width smaller than the ideal scan width, and the detection light L <b> 2 is more central than the light detection unit 403. The trajectory when turning back at a position near the point is shown. When the detection light L2 is scanned by the scanning locus SC1, the light detection unit 403 does not detect the light L2, and as shown in FIG. Is output. In this case, the control unit 601 generates a drive signal that increases the swing angle of the reflection mirror 104.

  A scanning trajectory SC <b> 2 illustrated in FIG. 7A indicates a trajectory when the detection light L <b> 2 returns at a position farther from the center point than the light detection unit 403. In this case, when the light detection unit 403 crosses the light detection unit 403 when the light L2 scans in a direction away from the center point, and when the light L2 crosses the light detection unit 403 when the light L2 travels in the direction of the center point. And detects the light L2. Therefore, as illustrated in FIG. 7B, the light detection unit 403 outputs a signal C2 such that two continuous peaks are generated at a substantially constant interval Tb.

In the signal C2, when the time between two consecutive peaks is Ta and the time between the two consecutive peaks and the next two peaks is Tb, the scanning width h of the light L2 is expressed by the equation (1). be able to.
h = 2d / {sin (π / 2) − (πTa / Tb)} (1)

  The calculation unit 604 calculates the scanning width h using the equation (1). Further, the calculation unit 604 calculates the swing angle of the reflection mirror 104 based on the calculated scanning width h. The calculation unit 604 derives the state of the frequency and phase at which the reflection mirror 104 is driven, in addition to the swing angle at which the reflection mirror 104 is actually displaced. Based on the calculation result by the calculation unit 604, the control unit 601 generates a drive signal that forms a swing angle, frequency, and phase for the reflection mirror 104 to scan the laser light L1 with an ideal amplitude. The reflection mirror 104 is driven based on the signal from the light detection unit 403 by positively feeding back the signal from the light detection unit 403 in this way. A DSP (digital signal processor) that performs a calculation for calculating the swing angle of the reflection mirror 104 based on a signal from the light detection unit 403 can be used as the calculation unit 604. By using the DSP, the processing by the calculation unit 604 can be performed quickly. Note that the calculation unit 604 may calculate the amplitude h based on another formula different from the formula (1). The calculation unit 604 may calculate the approximate value of the amplitude h by a simpler calculation using the equation (1). As a result, the processing by the calculation unit 604 can be quickly performed, and the calculation unit 604 can have a simple configuration.

  The resonance frequency of the reflection mirror 104 is determined according to the Young's modulus of the members constituting the reflection mirror 104. Since the Young's modulus changes according to changes in temperature, the resonance frequency of the reflection mirror 104 depends on the heat accumulated in the optical scanning device 120 and the ambient temperature due to part of the laser light being absorbed by the reflection mirror 104. The reflection mirror 104 is easily changed by the influence of heat generated by driving the reflection mirror 104. When the resonance frequency of the reflection mirror 104 changes, the driving of the reflection mirror 104 tends to become unstable, for example, the swing angle is remarkably reduced even if the reflection mirror 104 is always driven at a substantially constant cycle. In the present invention, the signal obtained by detecting the displacement of the reflecting mirror 104 is positively fed back to control the driving of the reflecting mirror 104, whereby the reflecting mirror 104 can be stably resonated.

  The optical scanning device 120 of the present invention is configured to detect the displacement of the reflection mirror 104 using light, thereby avoiding the generation of a force that prevents the reflection mirror 104 from vibrating. it can. Further, by adopting a configuration in which light is detected by the light detection unit 403, it is possible to accurately detect the displacement of the reflection mirror 104. By positively feeding back a signal obtained by detecting the displacement of the reflection mirror 104, the reflection mirror 104 can be stably resonated. As a result, the laser beam can be scanned efficiently and stably with the same scanning width. In addition, by stably scanning the screen 110 with laser light, a high-quality image can be stably displayed.

  The process from the detection result by the light detection unit 403 to the calculation of the swing angle of the reflection mirror 104 is not limited to the above. Of the signals from the light detection unit 403, the swing angle of the reflection mirror 104 may be calculated by another method different from the above. If the swing angle of the reflection mirror 104 can be calculated, the light detection unit 403 may be provided at a position different from the above position.

  FIG. 8 illustrates the configuration of the optical scanning device 820 and the behavior of the laser L1 from the main light source unit 101 according to a modification of the present embodiment. The optical scanning device 820 of this modification can be applied to the image display device 100 described above. 8 mainly shows the behavior of the laser light L1 from the optical scanning device 820 to the screen 110, and the overall configuration of the image display device is not limited to that shown in the figure. The optical scanning device 820 scans the laser light L <b> 1 from the main light source unit 101 using the two reflecting mirrors 104 and 804. The reflection mirror 104 is a first reflection mirror that scans the laser light L1 from the main light source unit 101 in the horizontal direction that is the first direction. The reflection mirror 804 is a second reflection mirror that scans the laser light L1 from the main light source unit 101 in a vertical direction that is a second direction substantially orthogonal to the first direction.

  The reflection mirror 804 is provided at a position where the laser light L1 reflected by the reflection mirror 104 enters. The reflection mirror 804 rotates around a torsion spring 802 that is a rotation axis. The torsion spring 802 is provided in a direction substantially orthogonal to the torsion spring 202 provided on the reflection mirror 104. By using the two reflection mirrors 104 and 804, the laser light L1 from the main light source unit 101 scans in the two-dimensional direction in the scanning area AR1 of the screen 110. During one frame period of the image, the reflection mirror 104 scans the laser beam a plurality of times in the horizontal direction while the reflection mirror 804 scans the laser beam once in the vertical direction. The reflection mirror 104 is driven at high speed and efficiency at the resonance frequency. On the other hand, the reflecting mirror 804 may be driven at a frequency other than the resonance frequency because it may be driven at a slower speed than the reflecting mirror 104.

  The light detection unit 403 and the detection light source unit 401 are provided corresponding to the reflection mirror 104. Assuming that the surface of the reflection mirror 104 that reflects the laser light L1 from the main light source unit 101 is a surface, the detection light source unit 401 and the light detection unit 403 are provided in a space to which the surface of the reflection mirror 104 is directed. The detection light source unit 401 and the light detection unit 403 are positioned so that the detection light L2 reflected by the reflection mirror 104 travels in a different direction from the light L1 from the main light source unit 101 reflected by the reflection mirror 104. Is provided.

  By providing the light detection unit 403 and the light source unit 401 for detection with respect to the reflection mirror 104 out of the two reflection mirrors 104 and 804, the light detection unit 403 can constantly transmit the light L2 for each cycle in which the reflection mirror 104 vibrates. The amplitude can be detected. Therefore, the swing angle of the reflection mirror 104 that resonates between the two reflection mirrors 104 and 804 can be detected with high frequency and can be accurately controlled. Thereby, the laser beam L1 can be accurately scanned with the same scanning width in the first direction in which the laser beam L1 scans by causing the reflection mirror 104 to resonate.

  The light detection unit and the detection light source unit are not limited to the configuration provided for the reflection mirror 104 that scans the laser light L1 in the horizontal direction. The light detection part and the light source part for detection should just be the structure provided about at least one of a 1st reflective mirror and a 2nd reflective mirror. For example, when the second reflection mirror that scans the laser light L1 in the vertical direction is resonated, the light detection unit and the detection light source unit can be provided for the second reflection mirror. Moreover, it is good also as providing a light detection part and a light source part for a detection in a 1st reflective mirror and a 2nd reflective mirror, respectively. Further, one of the first reflecting mirror and the second reflecting mirror that resonates is detected by using the detection light, and the other is detected by other methods other than using light, for example, by generating an electromotive force. It is good also as detecting a displacement. In the first embodiment, the scanning width is adjusted when the reflecting mirror is resonated. However, when the reflecting mirror is vibrated without using the resonance, the swing angle is detected as in the present embodiment. The scan width can be adjusted.

  FIG. 9 explains the configuration of the optical scanning device 920 according to the second embodiment of the present invention and the behavior of the laser L3 from the main light source unit 101. In FIG. The optical scanning device 920 of the present embodiment can be applied to the image display device 100 of the first embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. The optical scanning device 920 is characterized by supplying light for detecting the displacement of the reflection mirror 902 using the main light source unit 101. The main light source unit 101 supplies laser light to display an image and to detect displacement of the reflection mirror 902. The reflection mirror 902 reflects the laser beam L3 from the main light source unit 101 and vibrates, thereby scanning the laser beam L3 in a two-dimensional direction.

  FIG. 10 shows a perspective configuration of the reflection mirror 902. The reflection mirror 902 can be configured by forming a highly reflective member, for example, a metal thin film such as aluminum or silver, like the reflection mirror 104 of the first embodiment. The reflection mirror 902 is connected to the outer frame portion 904 by a torsion spring 907 that is a rotation shaft. The reflection mirror 902 rotates around the torsion spring 907 to scan the laser light L3 in the horizontal direction that is the first direction. The outer frame portion 904 is provided with a torsion spring 906 that is a rotation axis substantially orthogonal to the torsion spring 907. The outer frame portion 904 rotates around the torsion spring 906. The reflection mirror 902 scans the laser light L3 in the vertical direction, which is the second direction, by rotating around the torsion spring 906 together with the outer frame portion 904.

  FIG. 11 illustrates a reflection mirror 902 and a configuration for driving the reflection mirror 902. The first electrodes 1001 and 1002 are provided at positions that face the outer frame portion 904 and are substantially symmetrical with respect to the torsion spring 906. When a voltage is applied to the first electrodes 1001 and 1002, a predetermined force according to a potential difference, for example, an electrostatic force is generated between the first electrodes 1001 and 1002 and the outer frame portion 904. By alternately applying a voltage to the first electrodes 1001 and 1002, the outer frame portion 904 rotates about the torsion spring 906.

  In detail, the torsion spring 907 includes a first torsion spring 1007 and a second torsion spring 1008. A mirror side electrode 1005 is provided between the first torsion spring 1007 and the second torsion spring 1008. The second electrode 1006 is provided at a position facing the mirror side electrode 1005. When a voltage is applied to the second electrode 1006, a predetermined force corresponding to the potential difference, for example, an electrostatic force, is generated between the second electrode 1006 and the mirror side electrode 1005. When a voltage having the same phase is applied to any of the second electrodes 1006, the reflection mirror 902 rotates about the torsion spring 907.

  The reflection mirror 902 is thus driven to scan the laser beam L3 in the two-dimensional direction. The reflection mirror 902 is driven at the resonance frequency in the horizontal direction in the same manner as the reflection mirror 104 of the first embodiment. Each configuration for driving the reflection mirror 902 and the reflection mirror 902 can be created by, for example, MEMS (Micro Electro Mechanical Systems) technology. The optical scanning device 920 may be configured to scan the laser light L3 in a two-dimensional direction using two reflecting mirrors, similarly to the optical scanning device 820 described above.

  Returning to FIG. 9, the main light source unit 101 emits laser light for detecting the displacement of the reflection mirror 902 to the upper outer edge, which is the peripheral part of the scanning area AR <b> 1 for scanning the laser light L <b> 3 from the main light source unit 101. Supply. Further, the main light source unit 101 supplies laser light corresponding to the image signal to a region other than the upper outer edge that supplies laser light for detecting the displacement of the reflection mirror 902 in the scanning region AR1. Note that the laser beam for detection supplied from the main light source unit 101 is visible light.

  FIG. 12 illustrates the configuration of the portion of the screen 110 surrounded by the broken line shown in FIG. 9 and the configuration of the scanning area AR1 in the vicinity of the upper outer edge. The main light source unit 101 supplies laser light for detecting the displacement of the reflection mirror 902 to the upper outer edge AR3. The main light source unit 101 supplies laser light corresponding to the image signal to the area AR2 other than the upper outer edge AR3 in the scanning area AR1. The area AR2 is an image display area scanned with a laser beam corresponding to the image signal. When supplying the detection laser beam to the upper outer edge AR3, the reflection mirror 902 is displaced so as to scan the laser beam to the uppermost position in the vertical direction.

  The light detection unit 1203 is provided in the upper outer edge AR3 at a position closer to the center point than the position where the detection laser light is turned back when the reflection mirror 104 vibrates in the horizontal direction. The center point is the incident position of the detection laser beam when the deflection angle of the reflection mirror 104 around the torsion spring 907 is 0 degree. The optical scanning device 920 can detect the displacement of the reflection mirror 902 using the light supplied from the main light source unit 101 by providing the light detection unit 1203 at the upper outer edge AR3. As the light detection unit 1203, for example, a phototransistor or a photocell can be used similarly to the light detection unit 403 of the first embodiment.

  A light absorption unit 1205 is provided in a portion other than the portion where the light detection unit 1203 is provided in the upper outer edge AR3. The light absorption unit 1205 absorbs laser light that scans the upper outer edge AR3 in order to detect the displacement of the reflection mirror 902. When light for detecting the displacement of the reflection mirror 902 is absorbed by the light absorbing unit 1205, only light corresponding to the image signal can be advanced toward the viewer. Thereby, a reduction in contrast of the image can be reduced.

  In this embodiment, when the reflection mirror 902 is displaced so as to scan the laser beam to the uppermost position in the vertical direction, the light detection unit 403 detects the laser beam for detection that scans in the horizontal direction. . For this reason, the amplitude of the laser beam can be detected for each frame period in which the entire scanning area AR1 is scanned once by the laser beam. Thereby, the reflection mirror 902 can be resonated stably. The optical scanning device 920 can scan the laser light efficiently and stably with the same scanning width. Further, by supplying laser light for detecting the displacement of the reflection mirror 902 from the main light source unit 101, a new light source unit for supplying detection light becomes unnecessary. Thereby, the optical scanning device 920 can have a simple configuration.

  The main light source unit 101 is not limited to a configuration that supplies laser light for detecting the displacement of the reflection mirror 902 to the upper outer edge of the scanning area AR1. The main light source unit 101 may supply laser light for detecting the displacement of the reflection mirror 902 to the peripheral part of the scanning area AR1, for example, the lower outer edge part of the scanning area AR1. When the reflection mirror 902 is resonated to scan the laser beam in the vertical direction, the main light source unit 101 supplies the laser beam for detection to the right outer edge or the left outer edge of the scanning area AR1. It's also good. Furthermore, the light detection unit 1203 may be provided in a region for supplying laser light for detecting the displacement of the reflection mirror 902 from the main light source unit 101, and is not limited to the configuration provided in the upper outer edge portion of the scanning region AR1. . In the second embodiment, the scanning width is adjusted when the reflecting mirror is resonated. However, when the reflecting mirror is vibrated without using the resonance, the swing angle is detected in the same manner as in the present embodiment. The scan width can be adjusted.

  FIG. 13 shows a schematic configuration of an image display apparatus 1000 according to Embodiment 3 of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. The image display apparatus 1000 is a so-called front projection type projector that supplies laser light to a screen 1015 provided on the viewer side and observes an image by observing light reflected by the screen 1005. The image display apparatus 1000 includes the optical scanning device 120 as in the first embodiment.

  An exit window 1010 made of a transparent member such as glass or transparent resin is provided on the surface of the image display apparatus 1000 on the viewer side. Laser light from the optical scanning device 120 passes through the exit window 1010 and then enters the screen 1015. In this embodiment, the light detection unit may be provided around the reflection mirror 104 as in the first embodiment, or may be provided in the exit window 1010 or the screen 1015 by applying the second embodiment. In the case where the light detection unit is provided in the emission window 1010, the light absorbing unit can be used to block light for detecting the displacement of the reflection mirror 104. In the case where the light detection unit is provided on the screen 1015, the light absorption unit may be used to prevent the light for detecting the displacement of the reflection mirror 104 from being reflected from the screen 1015 toward the viewer. it can. By using the optical scanning device 120, the laser beam can be efficiently scanned on the screen 1015 and stably with the same scanning width. Thereby, the image display apparatus 1000 can stably display a high-quality image.

  In each of the above-described embodiments, the optical scanning device is configured to use the main light source unit 101 that supplies laser light. However, the configuration is not limited thereto as long as the configuration can supply beam-shaped light. For example, the main light source unit 101 may be configured to use a solid light emitting element such as a light emitting diode element (LED). Further, the optical scanning device of the present invention may be used in an electronic device that scans laser light, such as a laser printer or a barcode reader, in addition to the image display device.

  As described above, the optical scanning device according to the present invention is useful when scanning light according to an image signal, and is particularly suitable for use in an image display device for displaying a presentation or a moving image.

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 the planar structure of a reflective mirror. The figure explaining the drive of a reflective mirror. The figure explaining the structure for detecting the displacement of a reflective mirror. The figure explaining the position which provides a photon detection part. The figure which shows the block structure for driving a reflective mirror. The figure explaining the scanning width | variety of the light for a detection. The figure explaining the signal showing the displacement of a reflective mirror. FIG. 6 is a diagram illustrating a configuration of an optical scanning device and a behavior of light according to a modification of the first embodiment. FIG. 6 is a diagram illustrating the configuration of an optical scanning device according to Embodiment 2 of the present invention and the behavior of light. The figure which shows the isometric view structure of a reflective mirror. The figure explaining the structure for driving a reflective mirror and a reflective mirror. The figure explaining the structure of the scanning area | region of the upper outer edge part vicinity. 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 Main light source part, 104 Reflection mirror, 105 Reflection part, 107 Case, 110 Screen, 120 Optical scanning device, 201 Fixed part, 202 Torsion spring, 204 Movable side electrode, 205 Fixed side electrode, 401 Detection Light source unit, 403 light detection unit, S virtual plane, SC scanning locus, 601 control unit, 602 driving unit, 604 arithmetic unit, SC1, SC2 scanning locus, 802 torsion spring, 804 reflection mirror, 820 optical scanning device, AR1 scanning Area, 902 reflection mirror, 904 outer frame, 906, 907 torsion spring, 920 optical scanning device, 1001, 1002 first electrode, 1005 mirror side electrode, 1006 second electrode, 1007 first torsion spring, 1008 first 2 torsion springs, 1203 light detector, 1205 light absorber, AR2 Image display area, AR3 upper outer edges, 1000 an image display device, 1010 exit window 1015 screen

Claims (9)

A main light source for supplying beam-shaped light;
A reflection mirror that reflects and vibrates light from the main light source unit;
A light detection unit for detecting light for detecting the displacement of the reflection mirror,
The reflection mirror is driven based on a signal from the light detection unit.   The optical scanning device according to claim 1, further comprising a detection light source unit that supplies light for detecting the displacement of the reflection mirror.   The optical scanning device according to claim 2, wherein the light source unit for detection supplies light having a wavelength region different from the wavelength region of visible light.   The optical scanning device according to claim 3, wherein the detection light source unit supplies infrared light. The reflection mirror scans the light from the main light source unit in a first direction and the light from the main light source unit in a second direction substantially orthogonal to the first direction. A second reflecting mirror,
The optical scanning device according to claim 2, wherein the light detection unit and the detection light source unit are provided for at least one of the first reflection mirror and the second reflection mirror. .   The optical scanning device according to claim 1, wherein the main light source unit supplies light for detecting displacement of the reflecting mirror. An image display device that displays an image by light from an optical scanning device,
The optical scanning device includes:
A main light source for supplying beam-shaped light;
A reflection mirror that reflects and vibrates light from the main light source unit;
A light detection unit for detecting light for detecting the displacement of the reflection mirror,
The image display device, wherein the reflection mirror is driven based on a signal from the light detection unit. The main light source unit supplies light for detecting the displacement of the reflection mirror to a peripheral part of a scanning region that scans light from the main light source unit,
The image display device according to claim 7, wherein the light detection unit is provided in the peripheral part.   9. The light absorbing portion according to claim 8, further comprising a light absorbing portion that is provided in a portion of the peripheral portion other than the portion where the light detecting portion is provided and absorbs light for detecting the displacement of the reflecting mirror. Image display device.

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