JP2011227379A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display device that does not need to be equipped with a detector for detecting the angle of an mirror for each scanner.SOLUTION: An image display device comprises: a first scanner 80 and a second scanner 90 for scanning a light beam emitted from a light source 20; a half mirror 98 provided on a light path between the first scanner 80 and the second scanner 90; a light detector 97 for detecting the intensity and timing of the incident light beam scanned by the first scanner 80 and reflected by the half mirror; a first reflector 41 and a second reflector 42 arranged at an image plane position formed by the light beam scanned by the second scanner 90 for reflecting the light beam scanned by the second scanner 90; and an optical member 43 for bringing the light path of the incident light beam scanned by the first scanner 80, reflected by each of the first reflector 41 and the second reflector 42, and reflected by the half mirror 98 to enter the light detector to the same light path as the light path of the light beam scanned by the first scanner 80 and reflected by the half mirror 98.

Description

  The present invention relates to an image display apparatus, and more particularly to an optical scanning type image display apparatus that displays an image by two-dimensionally scanning a light beam having an intensity corresponding to an image signal.

  Conventionally, a retinal scanning image display device that displays an image by scanning a light beam having an intensity corresponding to an image signal on at least one retina of a user, or a light beam having an intensity corresponding to an image signal on a screen. An image display device such as a screen scanning type image display device that scans and displays an image is known.

  For example, in the image display device described in Patent Document 1 below, a first scanning unit that scans a light beam emitted from a light source unit in a first direction, and a light beam scanned by the first scanning unit as the first direction. An image is displayed by scanning the light flux with a second scanning unit that scans in a second direction that is substantially orthogonal. The first direction is, for example, the horizontal direction, and the second direction is, for example, the vertical direction.

  The first scanning unit and the second scanning unit include, for example, an optical scanning element that can swing a mirror unit on which a reflecting surface is formed around an oscillation axis, and the mirror unit is configured based on an input drive signal. Swing and scan the light beam.

  Among the optical scanning elements of the first scanning unit and the second scanning unit, the mirror unit of the optical scanning element of the second scanning unit is displaced at an angle corresponding to the signal level of the drive signal. However, the relationship between the signal level of the drive signal and the actual angle of the mirror portion changes due to ambient temperature, aging, individual differences, and the like. In order to scan the light beam in a desired direction by the mirror unit, it is necessary for the control unit that drives the optical scanning element to know the relationship between the signal level of the drive signal and the actual angle of the mirror unit. Therefore, in the conventional scanning part, the detection part which detects the angle of a mirror part is provided (refer patent documents 2-4).

JP 2009-014791 A JP 2009-229517 A JP 2009-169325 A JP 2008-129069 A

  However, in the conventional image display apparatus, it is necessary to provide a detection unit that detects the angle of the mirror unit for each scanning unit.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an image display device that does not require a detection unit that detects the angle of the mirror unit for each scanning unit.

  In order to achieve the above object, the invention according to claim 1 oscillates the first scanning unit that scans the light beam emitted from the light source unit in the first direction and the mirror unit having the reflecting surface about the oscillation axis. A second scanning unit that scans the light beam scanned by the first scanning unit in a second direction substantially orthogonal to the first direction, and an optical path between the first scanning unit and the second scanning unit. And a light detector that detects the intensity and timing of a light beam that is scanned at a predetermined position in the first direction by the first scanning unit and that is reflected by the half mirror and incident thereon A first reflecting portion and a second reflecting portion, which are disposed at an image plane position formed by the light beam scanned by the second scanning portion and respectively reflect the light beam scanned by the second scanning portion; Before being scanned to a predetermined position in the first direction by one scanning unit The half mirror is scanned by the first scanning unit to a predetermined position in the first direction on the optical path of the light beam reflected by the first reflecting unit and the second reflecting unit, reflected by the half mirror, and incident. An optical member that is incident on the light detection unit as the same optical path as the light beam reflected by the light beam, and outputs a drive signal to the first scanning unit and the second scanning unit, respectively, to output the first scanning unit and the second scanning unit. A control unit that controls the scanning unit and detects the scanning position of the first scanning unit based on the timing at which the light detection unit detects the light beam, and emits the light beam according to the image signal from the light source unit. And so on.

  According to a second aspect of the present invention, in the image display device according to the first aspect of the present invention, the image display device further includes an angle detection unit that detects an angle around the swing axis of the mirror unit, and the control unit includes the second scanning unit. And the light beam emitted from the light source unit is incident on the first reflecting unit and reflected, and is detected by the angle detection unit when a light beam having a predetermined intensity or more is detected by the light detection unit. In addition, the first process for acquiring the angle information as the first calibration point information and the second scanning unit are controlled so that the light beam emitted from the light source unit is incident on the second reflecting unit and reflected. A second process for acquiring information on the angle detected by the angle detection unit as information on a second calibration point when a light beam having a predetermined intensity or higher is detected by the light detection unit, and the first calibration point. And information on the second calibration point , And executes a third process of calibrating the detection result of the angle detection unit.

  According to a third aspect of the present invention, in the image display device according to the second aspect, the mirror section of the second scanning section rotates at an angle corresponding to the signal level of the drive signal. The control unit has angle / level information that defines a relationship between an angle around the swing axis of the mirror unit and a signal level of the drive signal, and the information when the first calibration point information is acquired The angle / level information is corrected based on the signal level of the drive signal and the signal level of the drive signal when the information of the second calibration point is acquired.

  According to a fourth aspect of the present invention, in the image display device according to any one of the first to third aspects, the reflectance of the light beam by the first reflecting unit is set as the reflectance of the light beam by the second reflecting unit. The first reflection part and the second reflection part are arranged to be separated from each other by a predetermined distance in the second direction.

  The invention according to claim 5 is the image display device according to any one of claims 1 to 4, further comprising a telecentric optical system that enters the light beam scanned by the second scanning unit, wherein the image plane position is It is formed by a telecentric optical system.

  The invention according to claim 6 is the image display device according to any one of claims 1 to 5, wherein the image display device is provided on an optical path between the half mirror and the first and second reflecting portions. A first λ / 4 plate and a second λ / 4 plate provided on an optical path between the half mirror and the optical member, and the half mirror is made to have a polarization state of an incident light beam As a polarization beam splitter whose reflectivity is determined by the light beam, the light beam emitted from the light source unit and passed through the half mirror is incident on the first and second reflection units via the first λ / 4 plate, and The light beams reflected by the first and second reflecting sections are detected by the light sequentially through the first λ / 4 plate, the second λ / 4 plate, the optical member, and the second λ / 4 plate. It is made to enter into a part.

  The invention according to claim 7 is the image display device according to any one of claims 1 to 6, wherein the control unit causes the light beam emitted from the light source unit to emit light from the first reflecting unit and the first unit. 2 A light beam is emitted from the light source unit at a timing not incident on the reflection unit, and at this time, a scanning position of the first scanning unit is detected based on a detection timing of the light detection unit, and the image from the light source unit is detected. A light beam corresponding to the signal is emitted from the light source unit.

  According to an eighth aspect of the present invention, in the image display device according to any one of the first to seventh aspects, the invalid scanning range outside the effective scanning range for scanning the luminous flux having the intensity corresponding to the image signal. A light-shielding part that blocks passage of the light beam scanned in Step 1, wherein the light-shielding part is located downstream of the first reflecting part and the second reflecting part, and the control part includes the first scanning part and When the scanning position by the second scanning unit is in the invalid scanning range, the light beam detected by the light detection unit is emitted from the light source unit.

  The invention according to claim 9 is the image display device according to any one of claims 1 to 8, wherein the control unit performs the first scan when performing the first process and the second process. This is characterized in that the scanning of the part is stopped.

  According to a tenth aspect of the present invention, in the image display device according to any one of the first to ninth aspects, a light beam having an intensity corresponding to the image signal is transmitted by the first scanning unit and the second scanning unit. It scans and makes it enter into a user's eyes, and the image according to the said image signal is projected on the said user's retina, It is characterized by the above-mentioned.

  According to the present invention, since the light beam reflected by the first reflection unit and the second reflection unit is detected by the detection unit, it is not necessary to provide a detection unit for detecting the angle of the mirror unit for each scanning unit.

It is a figure which shows the external appearance of the retinal scanning image display apparatus (henceforth RSD) which concerns on this embodiment. It is explanatory drawing which showed the electrical structure and optical structure of RSD which concern on this embodiment. It is explanatory drawing which showed the state of the scanning of the light beam by a scanning part. It is a figure which shows the specific structure of the optical scanning element shown in FIG. It is the equivalent circuit of the detection part comprised by a piezoresistive element. It is a figure which shows the change of the resistance value of a piezoresistive element by torsional displacement. It is a figure which shows arrangement | positioning of the light-shielding part shown in FIG. 1, and a 1st and 2nd reflection part. It is a figure for demonstrating the optical path of the laser beam of RSD shown in FIG. It is a figure for demonstrating the optical path of the laser beam of RSD shown in FIG. It is a figure for demonstrating the detection method of the laser beam by a photon detection part. It is a figure which shows the relationship between the detection voltage of a detection part, and the angle of the mirror part of a 2nd optical scanning element. It is a figure which shows the structure of the control part shown in FIG. It is a figure which shows an example of a target angle table. It is a figure for demonstrating operation | movement of the control part shown in FIG. It is a figure for demonstrating operation | movement of the control part shown in FIG. It is a figure for demonstrating the other optical path of a laser beam. It is a figure for demonstrating the other optical path of a laser beam. It is a figure which shows the relationship between the voltage of a 2nd drive signal, and the angle of the mirror part of a 2nd optical scanning element.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the following description, a retinal scanning image display device (RSD) that scans a light beam with an intensity corresponding to an image signal, projects an image on at least one retina of a user, and displays the image is taken as an example. I will give you a description. The present invention is not limited to RSD, and can be applied to other image display devices that display an image by scanning a light beam.

[1. Appearance of RSD]
As shown in FIG. 1, the RSD 1 according to the present embodiment is a head-mounted display that is used by being mounted on the head, and includes a control unit 2 and a head-mounted tool 5. The control unit 2 and the head mounting tool 5 are connected via the transmission cable portion 4. The transmission cable unit 4 includes an optical fiber cable 50 (see FIG. 2) that transmits the laser light emitted from the control unit 2. The transmission cable unit 4 includes a signal (for example, a first drive signal) for synchronizing between a scanning unit 30 provided in the projection unit 6 described later and a light source unit 20 described later provided in the control unit 2. 61 and a drive signal transmission cable for transmitting the second drive signal 62).

  The control unit 2 emits laser light having an intensity corresponding to the image signal S input from the external input terminal 7 (hereinafter referred to as image forming laser light) to the transmission cable unit 4.

  The head mounting tool 5 includes a projection unit 6 and a glasses-type frame 14 that supports the projection unit 6. The projection unit 6 scans the laser beam transmitted through the optical fiber cable 50 of the transmission cable unit 4 in a two-dimensional direction by the scanning unit and projects the laser beam on the user's eye 101. As a result, an image scanned in the two-dimensional direction is projected onto the retina of the user's eye 101, and the user visually recognizes the image corresponding to the image signal S.

  The projection unit 6 is provided with a half mirror 15 at a position facing the user's eye 101. The external light L1 passes through the half mirror 15 and enters the user's eye 101, and the laser light L2 emitted from the projection unit 6 is reflected by the half mirror 15 and enters the user's eye 101. Accordingly, the user can visually recognize the image of the laser light L2 superimposed on the outside scene of the external light L1.

  As described above, the RSD 1 is a see-through type RSD in which an image according to the image signal S and an outside scene are overlapped to form an image on the retina of the user's eye 101. Here, laser light that is advantageous in terms of efficiency is used as an example of the light flux, but the light flux is not limited to laser light.

[2. Electrical configuration and optical configuration of RSD1]
Next, the electrical configuration and optical configuration of the RSD 1 will be described with reference to FIG.

  The control unit 2 includes a control unit 10 and a light source unit 20.

  Based on the image signal S (for example, NTSC composite signal, component signal) input from the external input terminal 7, the control unit 10 generates each signal that is an element for forming an image in units of pixels. That is, the control unit 10 generates and outputs an R (red) drive signal 60r, a G (green) drive signal 60g, and a B (blue) drive signal 60b. Further, the control unit 10 outputs a first drive signal 61 used in the first scanning unit 80 and a second drive signal 62 used in the second scanning unit 90, respectively.

  The light source unit 20 is provided with an R laser driver 66, a G laser driver 67, and a B laser driver 68. The R laser driver 66, the G laser driver 67, and the B laser driver 68 are based on the R drive signal 60r, the G drive signal 60g, and the B drive signal 60b output from the control unit 10, respectively. , And B laser 65 are supplied with drive current, respectively. Each of the lasers 63, 64, and 65 emits laser light whose intensity is modulated in accordance with the drive current supplied from each of the laser drivers 66, 67, and 68. Each laser 63, 64, 65 can be configured as, for example, a semiconductor laser or a solid-state laser with a harmonic generation mechanism. If a semiconductor laser is used, the drive current can be directly modulated to modulate the intensity of the laser beam. However, if a solid-state laser is used, each laser is equipped with an external modulator, and the intensity of the laser beam is modulated. Need to do.

  Furthermore, the light source unit 20 is provided with collimating optical systems 71, 72, 73, dichroic mirrors 74, 75, 76 for combining the collimated laser beams, and a coupling optical system 77. The R (red) laser light Lr, G (green) laser light Lg, and B (blue) laser light Lb emitted from the lasers 63, 64, and 65 were collimated by collimating optical systems 71, 72, and 73, respectively. Later, the light enters the dichroic mirrors 74, 75, and 76. Thereafter, the laser beams Lr, Lg, and Lb of the three primary colors are wavelength-selectively reflected and transmitted by these dichroic mirrors 74, 75, and 76, reach the coupling optical system 77, and are combined to the optical fiber cable 50. Emitted. As described above, the laser light emitted to the optical fiber cable 50 is obtained by combining the intensity-modulated laser light of each color.

  The projection unit 6 is disposed on the optical path between the light source unit 20 and the user's eye 101, and includes a scanning unit 30 and a second relay optical system 95.

  The scanning unit 30 includes a collimating optical system (collimating lens) 79, a first scanning unit 80, a second scanning unit 90, a first relay optical system 85, and a light detection unit 97.

  The collimating optical system 79 collimates the laser light generated by the light source unit 20 and emitted through the optical fiber cable 50.

  The first scanning unit 80 and the second scanning unit 90 have a first direction X and a second direction Y in order to project the laser light incident from the optical fiber cable 50 onto the user's retina 101b as an image. It is an optical system that performs scanning. The first scanning unit 80 reciprocally scans the incident laser light that has been collimated by the collimating optical system 79 in the first direction X at a relatively high speed. The second scanning unit 90 scans the first scanning unit 80 in the first direction X, and the laser beam incident through the first relay optical system 85 including the lenses 85a and 85b is applied in the second direction Y. Scan relatively slowly. The second direction Y is a direction substantially orthogonal to the first direction X. For example, the first direction X can be the horizontal direction and the second direction Y can be the vertical direction.

  The first scanning unit 80 resonates the first optical scanning element 81 that scans laser light in the first direction X, and causes the mirror part 82a of the first optical scanning element 81 to resonate with the first optical scanning element 81. A first scanning drive circuit 83 that generates a drive signal for swinging around the swing axis Lx based on the first drive signal 61 is provided. The first optical scanning element 81 has a mirror part 82a on which a reflecting surface 82b is formed, and this mirror part 82a is supported by an elastic beam part 82c. The mirror portion 82a swings around the swing axis Lx due to torsional displacement (twist deformation) of the beam portion 82c, and scans the laser light in the first direction X. Although not shown, the first optical scanning element 81 has a piezoelectric element that applies vibration to the beam portion 82c. Mechanical displacement is applied to the piezoelectric element by the first drive signal 61, and the beam portion is caused by resonance vibration. A twist displacement is given to 82c.

  On the other hand, the second scanning unit 90 includes an electromagnetically driven second optical scanning element 91 having a mirror unit 110 for scanning laser light in the second direction Y, and the mirror unit 110 of the second optical scanning element 91. And a second scanning drive circuit 93 that generates and outputs a drive current that swings around the swing axis Ly in a non-resonant state at a current value corresponding to the voltage value of the second drive signal 62. The second scanning unit 90 scans laser light for forming an image in the second direction Y from the first scanning line toward the last scanning line for each frame of the image to be displayed. Here, “scanning line” means one scanning on one side in the first direction X by the first scanning unit 80. The configuration of the second optical scanning element 91 will be described in detail later. The second scanning unit 90 is provided with an angle detection unit 18 for detecting an angle around the swing axis Ly of the mirror unit 110 of the second optical scanning element 91. The configuration of the angle detection unit 18 is also described. This will be described in detail later.

  The half mirror 98 is provided on the optical path between the first scanning unit 80 and the second scanning unit 90, and reflects part of the laser light scanned in the first direction X and transmits the rest. . A light detection unit 97 is disposed within the scanning angle p of the laser light reflected by the half mirror 98. When the light detection unit 97 receives the laser light reflected by the half mirror 98, the light detection unit 97 generates a detection signal having a voltage value corresponding to the intensity of the received laser light and transmits the detection signal to the control unit 10. The detection of laser light by the light detection unit 97 will be described in detail later.

  The first relay optical system 85 that relays the laser light between the first scanning unit 80 and the second scanning unit 90 is a laser scanned in the first direction X by the mirror unit 82 a of the first optical scanning element 81. The light is converged on the reflection mirror of the second optical scanning element 91. Then, this laser beam is scanned in the second direction Y by the mirror part 110 of the second optical scanning element 91. The laser beam scanned by the second optical scanning element 91 is half-positioned in front of the eye 101 via the second relay optical system 95 in which two lenses 95a and 95b having positive refractive power are arranged in series. It is reflected by the mirror 15 and enters the user's pupil 101a. As a result, an image corresponding to the image signal S is projected on the retina 101b, and the user recognizes the laser light incident on the pupil 101a as an image. Further, the half mirror 15 transmits the external light L1 so as to enter the pupil 101a of the user, so that the user can visually recognize an image in which an image based on the laser light L2 is superimposed on an external scene based on the external light L1. can do.

  In the second relay optical system 95, the respective scanning lights are made substantially parallel to each other and converted into convergent laser lights by the lens 95a. That is, the lens 95a is an optical member that constitutes a telecentric optical system in which the reflecting surface 110a of the mirror unit 110 is the entrance pupil. Then, the respective laser beams are substantially collimated by the lens 95b and converted so that the center lines of these laser beams converge on the user's pupil 101a. In the present embodiment, a projection unit is configured by the lens 95b and the half mirror 15.

  At the position of the image plane (hereinafter referred to as “intermediate image plane”) formed by the second relay optical system 95 or in the vicinity thereof, an opening 96a through which the image forming laser beam scanned in the effective scanning range Z is passed is the central portion. And a light-shielding portion 96 formed in a frame shape. The light shielding unit 96 blocks light that has been scanned outside the effective scanning range Z from entering the lens 95 b so that unnecessary laser light does not enter the user's eye 101. The intermediate image plane has an image conjugate relationship with the retina 101b.

  FIG. 3 shows the relationship between the maximum scanning range G and the effective scanning range Z by the optical scanning elements 81 and 91 of the first scanning unit 80 and the second scanning unit 90. Here, the “maximum scanning range G” means the maximum range in which the first optical scanning element 81 of the first scanning unit 80 and the second optical scanning element 91 of the second scanning unit 90 can scan the laser beam. The maximum scanning range G is a scanning position of the scanning unit 30 when the scanning position of the first optical scanning element 81 is −X2 to + X2 and the scanning position of the second optical scanning element 91 is −Y2 to + Y2. is there. Further, the “effective scanning range Z” is the scanning unit 30 when the scanning position of the first optical scanning element 81 is −X1 to + X1 and the scanning position of the second optical scanning element 91 is −Y1 to + Y1. This is the scanning position, and the laser beam emitted from the light source unit 20 is scanned in this range. When the first optical scanning element 81 does not receive the first drive signal 61, the mirror part 110 of the first optical scanning element 81 is in the equilibrium position X0, and the second optical scanning element 91 receives the second drive signal 62. Is not input, the mirror part 110 of the second optical scanning element 91 is in the equilibrium position Y0.

  Of the maximum scanning range G, for image formation, the intensity of the light source unit 20 in accordance with the image signal S is modulated at the timing when the scanning position by the first optical scanning element 81 and the second optical scanning element 91 is within the effective scanning range Z. Laser light is emitted. As a result, the first optical scanning element 81 and the second optical scanning element 91 scan the image forming laser beam in the effective scanning range Z, and the image forming laser beam for one frame is scanned in the effective scanning range Z. The This scanning is repeated for each frame image.

[3. Specific Configuration of Second Optical Scanning Element 91 and Angle Detection Unit 18]
Next, specific configurations of the second optical scanning element 91 and the angle detection unit 18 will be described. FIG. 4 is a diagram showing a specific configuration of the second optical scanning element 91 and the angle detection unit 18.

  As shown in FIG. 4A, the second optical scanning element 91 includes a mirror part 110 on which a reflecting surface 110a is formed, a pair of beam parts 111a and 111b, a pair of support parts 112a and 112b, and a fixed part. 113a and 113b, and a base 114, and the mirror 110 is swung around the swing axis Ly to scan with the laser beam.

  The pair of beam portions 111a and 111b extend along the swing axis Ly to support both sides of the mirror portion 110 with elasticity, and the mirror portion 110 is supported by the swing displacement (twist deformation) of the swing portion Ly. It can swing around. The pair of support portions 112a and 112b support the other end of each of the pair of beam portions 111a and 111b with elasticity at the central portion, and fixed portions 113a and 113b whose both ends are fixed to the base 114. It is fixed to. As described above, the mirror portion 110 is supported by the pair of beam portions 111a and 111b and the pair of support portions 112a and 112b so as to be swingable around the swing axis Ly.

  Permanent magnets 115a and 115b are disposed in proximity to two sides parallel to the swing axis Ly of the mirror unit 110. The direction of the magnetic field formed by the permanent magnets 115a and 115b is parallel to the reflecting surface 110a of the mirror unit 110 in a stationary state and is orthogonal to the swing axis Ly. Further, as shown in FIG. 4B, a coil 116 is formed on the back surface of the mirror portion 110 opposite to the reflecting surface 110a. The electrode of the coil 116 is connected to the second scanning drive circuit 93 via the two beam portions 111a and 111b. With this configuration, when a drive current is passed through the coil 116, Lorentz force acts on the coil 116. For example, when a current is passed from the beam portion 111a side of the coil 116 to the 111b side of the coil 116 in the drawing view, the lower half of the coil 116 from the swing axis Ly in the drawing view has, for example, a Lorentz force on the surface side of the paper surface. The Lorentz force acts on the back side of the paper surface in the upper half coil 116 from the swing axis Ly in the drawing. As a result, a rotational torque is generated in the mirror unit 110 around the swing axis Ly. Therefore, by controlling the signal level of the drive current output from the second scanning drive circuit 93, the angle around the swing axis Ly of the mirror unit 110 can be controlled. The current value of the drive current output from the second scanning drive circuit 93 is proportional to the signal level of the second drive signal 62, and thus the control unit 10 has a signal level corresponding to the desired angle of the mirror unit 110. By outputting the second drive signal 62, the mirror unit 110 can be set to a desired angle.

  The second optical scanning element 91 is further provided with piezoresistive elements R1 to R4 as an angle detection unit 18 that detects an angle around the swing axis Ly of the mirror unit 110. The pair of piezoresistive elements R1 and R3 are disposed symmetrically with respect to the swing axis Ly on the support portion 112a. The piezoresistive element R1 is arranged on the support part 112a on the fixed part 113a side, and the piezoresistive element R3 is arranged on the support part 112a on the fixed part 113b side. Similarly, the pair of piezoresistive elements R2 and R4 are arranged symmetrically with respect to the swing axis Ly on the support portion 112b. The piezoresistive element R2 is arranged on the support part 112b on the fixed part 113a side, and the piezoresistive element R4 is arranged on the support part 112b on the fixed part 113b side.

  The resistance value of one pair of piezoresistive elements R1 and R3 changes according to the stress field generated in the vicinity of the swing axis Ly according to the torsional displacement generated in the beam portion 111a, and the other pair of piezoresistive elements. The resistance values of the elements R2 and R4 change depending on the stress field generated in the vicinity of the swing axis Ly according to the torsional displacement generated in the beam portion 111b.

  As shown in FIG. 4C, the pair of piezoresistive elements R1 and R3 are arranged in series between the power supply potential Vc and the ground potential GND. Similarly, the pair of piezoresistive elements R4 and R2 are arranged in series between the power supply potential Vc and the ground potential GND. That is, one end of the piezoresistive elements R1 and R4 is connected to the power supply of the power supply potential Vc, and the other end is connected to one end of the piezoresistive elements R2 and R3. The other ends of the piezoresistive elements R2 and R3 are connected to the ground of the ground potential GND.

  FIG. 5 is an equivalent circuit of the angle detector 18 configured by the piezoresistive elements R1 to R4 shown in FIG. As shown in the figure, the angle detector 18 uses a connection point between the pair of piezoresistive elements R1 and R3 as a first output node N1, and a connection point between the other pair of piezoresistive elements R4 and R2 as a second output. Node N2. The control unit 10 receives the voltage VPR + of the first output node N1 and the voltage VPR− of the second output node N2, and the voltage of the first output node N1 with reference to the voltage of the second output node N2. Is the detection voltage Vd (= [VPR +] − [VPR−]). When no drive current is supplied to the mirror unit 110, in other words, when the signal level of the second drive signal 62 is 0 [V], the resistance values of the piezoresistive elements R1 to R4 are not changed, and the piezoresistor When the initial resistance values of the elements R1 to R4 are the same, the detection voltage Vd is 0V.

  Here, assuming that each of the piezoresistive elements R1 to R4 has a characteristic that the resistance value increases due to the compressive stress and the resistance value decreases due to the tensile stress, the resistance value is as follows due to the displacement of the mirror portion 110. Changes. Here, it is assumed that the piezoresistive elements R1 to R4 have the same material and the same shape, and the same characteristics.

  For example, as shown in FIG. 6, when the mirror portion 110 is inclined at an angle θ around the swing axis Ly, the resistance values of the piezoresistive elements R1 and R2 increase due to compressive stress, and the piezoresistive elements R3, R3, The resistance value of R4 decreases due to the tensile stress. Therefore, the voltage VPR + at the first output node N1 decreases, the voltage VPR− at the second output node N2 increases, and the detection voltage Vd becomes negative. The absolute value of the detection voltage Vd increases as the angle θ of the mirror 110 around the swing axis Ly increases. On the other hand, when the mirror unit 110 is tilted in the direction opposite to the direction shown in FIG. 6, the detection voltage Vd becomes positive, and the absolute value of the detection voltage Vd increases as the angle of the mirror unit 110 around the swing axis Ly increases. growing.

  Thus, the inclination direction of the mirror unit 110 from the equilibrium state shown in FIG. 4 can be determined by the polarity of the detection voltage Vd, and the inclination angle of the mirror unit 110 can be determined by the magnitude of the detection voltage Vd. Using this principle, the control unit 10 detects the actual tilt angle of the mirror unit 110 around the swing axis Ly by the detection voltage Vd.

  By the way, the resistance values of the piezoresistive elements R1 to R4 change due to individual differences or temperature changes, and the resistance values also change due to secular changes or the like. For this reason, the relationship between the detection voltage Vd and the angle of the mirror unit 110 varies, and there is a possibility that the mirror unit 110 cannot be swung accurately.

  Therefore, in the RSD 1 according to the present embodiment, even if the relationship between the detection voltage Vd and the angle of the mirror unit 110 changes, the first mirror unit 110 can be oscillated with high accuracy. The reflection part 41, the 2nd reflection part 42, and the optical member 43 are provided. That is, by providing the first reflection unit 41, the second reflection unit 42, and the optical member 43, the laser beam scanned by the second scanning unit 90 is incident on the light detection unit 97, and the scanning position of the second scanning unit 90 is obtained. , And the relationship between the detection voltage Vd and the angle of the mirror unit 110 is calibrated. Hereinafter, the calibration process of the relationship between the detection voltage Vd and the angle of the mirror unit 110 will be specifically described.

[4. Calibration of relationship between detection voltage Vd and angle of mirror unit 110]
In addition to the detection of the scanning position of the laser beam by the first scanning unit 80, the light detection unit 97 detects the scanning position of the laser beam by the second scanning unit 90 as described above. The light detection unit 97 is disposed at a position where the laser light between the first scanning unit 80 and the second scanning unit 90 and reflected by the half mirror 98 is incident. Therefore, a configuration for allowing the laser beam that has passed through the half mirror 98 and scanned by the second scanning unit 90 to enter the light detection unit 97 is necessary. In the RSD 1 of the present embodiment, the first reflection unit 41, the second reflection unit 41, The reflection part 42 and the optical member 43 are provided.

  The first reflecting part 41 and the second reflecting part 42 are provided in the light shielding part 96. The surfaces of the first reflecting portion 41 and the second reflecting portion 42 are coated with a reflecting material to form a reflecting surface, and reflect the incident laser light. In the present embodiment, the reflectance of the laser light by the first reflecting portion 41 is made higher than the reflectance of the laser light by the second reflecting portion 42.

  As shown in FIGS. 2 and 7A, the light shielding portion 96 is formed in a frame shape by a light shielding plate that prevents the incident laser light from passing toward the lens 95b, and the surface of the light shielding plate. The first reflecting portion 41 and the second reflecting portion 42 are formed. As shown in the side view of FIG. 7B, the first reflecting portion 41 and the second reflecting portion 42 are provided upstream of the light shielding portion 96 in the optical path, and are scanned by the second scanning portion 90 and incident thereon. The light shielding unit 96 reflects the light and enters the reflection surface 110a of the mirror unit 110 of the second optical scanning element 91 through the optical path substantially the same as the incident optical path, that is, the lens 95a of the second relay optical system 95. It is inclined with respect to the surface. The inclination angle may be determined so that the normal lines of the first reflecting portion 41 and the second reflecting portion 42 are parallel to the principal ray of the laser light incident on the first reflecting portion 41 and the second reflecting portion 42. That is, the first reflection unit 41 and the second reflection unit 42 are arranged so as to be orthogonal to the incident direction of the laser light scanned by the second scanning unit 90.

  The first reflecting unit 41 is emitted from the light source unit 20 when the scanning position of the second scanning unit is in + Y3 (see FIG. 3) in the first invalid scanning range Yb1 in the scanning range in the second direction Y. It arrange | positions in the position into which a laser beam injects. In addition, the second reflecting unit 42 from the light source unit 20 when the scanning position of the second scanning unit is in -Y3 (see FIG. 3) in the second invalid scanning range Yb2 in the scanning range in the second direction Y. It arrange | positions in the position where the emitted laser beam enters. Thus, when the scanning position of the second scanning unit is on both sides of the scanning range in the second direction Y across the effective scanning range Ya (see FIG. 3) in the second direction Y, the light source unit 20 emits the light. By arranging the first reflecting portion 41 and the second reflecting portion 42 at the position where the laser beam is incident, the detection error of the angle detecting portion 18 can be calibrated with high accuracy.

  FIG. 8 shows a schematic diagram of the optical path of laser light from the optical fiber cable 50 to the second relay optical system 95. There are two optical paths of the laser light incident on the light detection unit 97: a first optical path and a second optical path.

  In the first optical path, the laser light emitted from the optical fiber cable 50 is reflected by the half mirror 98 through the collimating optical system 79, the reflection surface 82 b of the first optical scanning element 81, and the lens 85 a, and then to the light detection unit 97. Incident light (see FIGS. 8 and 9A).

  On the other hand, in the second optical path, the laser light emitted from the optical fiber cable 50 is collimated optical system 79, reflecting surface 82b of the first optical scanning element 81, lens 85a, half mirror 98, lens 85b, and second optical scanning element. The light is reflected by the first reflecting portion 41 or the second reflecting portion 42 via the reflecting surface 110a 91 and the lens 95a. Then, the laser light reflected by the first reflecting portion 41 or the second reflecting portion 42 is reflected by the half mirror 98 via the lens 95a, the reflecting surface 110a of the second optical scanning element 91, and the lens 85b, and further optically. The light is reflected by the member 43, passes through the half mirror 98, and enters the light detection unit 97 (see FIGS. 8 and 9B).

  The optical member 43 in the second optical path has a concave reflecting surface, reflects the laser beam incident after being reflected by the half mirror 98, passes through the half mirror 98, and enters the light detection unit 97. The optical path between the half mirror 98 and the light detection unit 97 is the same as the first optical path.

  In this way, by making the first optical path and the second optical path the same optical path between the half mirror 98 and the light detection unit 97, as shown in FIG. 10A, the light detection unit 97 from the first optical path. The timing at which the light enters the light receiving region 97a of the light detection unit 97 from the second optical path can be made the same.

  As shown in FIG. 3, the light detection unit 97 detects the laser beam scanned by the first scanning unit 80 when the scanning position of the first scanning unit 80 is + X3 of the invalid scanning range Xb in the first direction X. It is arranged at the incident position. Therefore, when the laser beam is emitted from the light source unit 20 when the scanning position of the first scanning unit 80 is + X3, the detection signal 99 is output from the light detection unit 97 as shown in FIG. The When the detection signal 99 is output from the light detection unit 97, the control unit 10 determines that the scanning position of the first scanning unit 80 is + X3, and the emission timing of the laser light for image formation from the light source unit 20 is determined. Is adjusted. That is, after the scanning position of the first scanning unit 80 is + X3, the control unit 10 next determines the timing at which the scanning position of the first scanning unit 80 becomes + X1 or −X1, and the first When the scanning position of the scanning unit 80 is within the effective scanning range Xa (see FIG. 3) in the first direction X, laser light for image formation is emitted from the light source unit 20.

  Furthermore, when the scanning position of the first scanning unit 80 is + X3 and the scanning position of the second scanning unit 90 is in + Y3 and −Y3 in the invalid scanning ranges Yb1 and Yb2 in the second direction Y, FIG. As shown in FIG. 4, a detection signal 99 is output from the light detection unit 97. The detection signal 99 at this time has a high signal level because the laser light from the first optical path and the laser light from the second optical path are incident on each other. Therefore, the control unit 10 can detect that the scanning position of the second scanning unit 90 is + Y3 or −Y3 when the detection signal 99 is a signal having a signal level equal to or higher than the first threshold. .

  In addition, since the reflectance of the first reflecting portion 41 is higher than the reflectance of the second reflecting portion 42, detection is performed when the scanning position of the second scanning portion 90 is + Y3 and when it is −Y3. The signal level of the signal 99 is different. Therefore, a second threshold value larger than the first threshold value is set, and whether the scanning position of the second scanning unit 90 is + Y3 or -Y3 is detected depending on whether the second threshold value is larger than the second threshold value. ing. That is, when the signal level of the detection signal 99 is equal to or higher than the second threshold, it is determined that the scanning position of the second scanning unit 90 is + Y3, and the signal level of the detection signal 99 is equal to or higher than the first threshold but is set to the second threshold. If not, it is determined that the scanning position of the second scanning unit 90 is -Y3. Since the scanning of the second scanning unit 90 is relatively slow and operates in synchronization with the waveform of the second drive signal 62, the control unit 10 determines that the scanning position of the second scanning unit 90 is close to + Y3. Or close to -Y3. Therefore, the reflectivity of the first reflector 41 and the reflectivity of the second reflector 42 are made the same, and the controller 10 outputs the second drive signal when the detection signal 99 is output from the light detector 97. Based on the signal level of 62, it may be determined whether the scanning position of the second scanning unit 90 is close to + Y3 or close to −Y3.

  When the control unit 10 determines that the scanning position of the second scanning unit 90 is + Y3 based on the detection signal 99 from the light detection unit 97, the control unit 10 determines the voltage value of the detection voltage Vd output from the angle detection unit 18 at this time. It is stored as a first calibration voltage Vd1 that is information of one calibration point. Similarly, when the control unit 10 determines that the scanning position of the second scanning unit 90 is −Y3 based on the detection signal 99 from the light detection unit 97, the detection voltage output from the angle detection unit 18 at this time. The voltage value of Vd is stored as a second calibration voltage Vd2 that is information on the second calibration point.

In the RSD 1 according to the present embodiment, the detection voltage Vd and the angle θ of the mirror unit 110 are in a proportional relationship, and the relationship between the detection voltage Vd and the angle θ of the mirror unit 110 is the first calibration voltage Vd1 and the second calibration. Based on the working voltage Vd2, it can be derived as shown in FIG.
In the figure,
α = (Vd1−Vd2) / 2θ3 (1)
β = (Vd1 + Vd2) / 2 (2)
It is.

  As described above, the control unit 10 can detect the sensitivity α and the offset β, which are the detection characteristics of the angle detection unit 18, based on the detection signal 99 from the light detection unit 97, and based on the sensitivity α and the offset β. The detection characteristics of the angle detector 18 are calibrated.

[5. Configuration of control unit 10]
Next, the configuration of the control unit 10 will be specifically described with reference to FIG.

  The control unit 10 includes a first scanning unit controller 120, an RGB laser controller 121, and a second scanning unit controller 122.

  The first scanning unit controller 120, the RGB laser controller 121, and the second scanning unit controller 122 are each performing synchronous communication. Therefore, the oscillation of the first optical scanning element 81 and the second optical scanning element 91 and the emission timing of the laser light from each of the lasers 63, 64, 65 are controlled to be synchronized with each other.

  The first scanning unit controller 120 transmits the first driving signal 61 to the first scanning driving circuit 83 of the first scanning unit 80 to operate the first optical scanning element 81 of the first scanning unit 80, and the light source unit 20. The first light scanning element 81 scans the laser light emitted from the first direction X. Further, the first scanning unit controller 120 receives the detection signal 99 from the light detection unit 97, and based on the detection signal 99, the swinging state (swinging frequency and swinging) of the mirror unit 82 a of the first optical scanning element 81 is detected. Amplitude) is detected, and the oscillation frequency of the mirror portion 82a is adjusted to the resonance frequency unique to the first optical scanning element 81. Thereby, the mirror part 82a is swung relatively fast around the rocking axis Lx by resonance.

  The RGB laser controller 121 receives an image signal S, and generates an R drive signal 60r, a G drive signal 60g, and a B drive signal 60b from the image signal S in units of pixels. The RGB laser controller 121 is electrically connected to the laser drivers 66, 67, and 68, and transmits drive signals 60r, 60g, and 60b to the laser drivers 66, 67, and 68, respectively.

  The second scanning unit controller 122 transmits the second drive signal 62 to the second scanning drive circuit 93 of the second scanning unit 90 to operate the second optical scanning element 91 of the second scanning unit 90, and the light source unit 20. The second light scanning element 91 scans the laser light emitted from the second direction Y. Further, the second scanning unit controller 122 detects the swinging state of the second optical scanning element 91 based on the detection voltage Vd from the angle detection unit 18.

  Further, the second scanning unit controller 122 receives the detection signal 99 from the light detection unit 97, detects the relationship between the detection voltage Vd and the angle of the mirror unit 110, and performs the second drive based on the detection result. The signal 62 is generated. By doing in this way, the mirror part 110 of the 2nd optical scanning element 91 can be rock | fluctuated accurately. Hereinafter, the configuration of the second scanning unit controller 122 will be specifically described.

  As shown in FIG. 12, the second scanning unit controller 122 includes a target angle command generation unit 131, an angle-voltage conversion unit 132, an angle-voltage conversion condition storage unit 133, a subtraction unit 134, a drive signal generation unit 135, and voltage correction. It has a condition storage unit 136.

  The target angle command generation unit 131 outputs the target angle of the mirror unit 110 corresponding to the direction to be scanned by the second optical scanning element 91 as a target angle command. In the target angle command generation unit 131, information on the target angle of the mirror unit 110 for one frame period T (see FIG. 3) is stored in the internal storage unit, and the information stored in this storage unit is sequentially read out. Output as target angle command. For example, as information on the target angle of the mirror unit 110 in one frame period, a target angle table having information from 1 to 1000th is stored in the storage unit, and information from 1 to 1000th is sequentially read out as a target angle command. Output. As described above, the target angle is in the range of + θ1 to −θ1 (see FIG. 3), and the target angle table is, for example, a table as shown in FIG. Note that the target angle of the mirror unit 110 may not be stored in advance, but may be calculated sequentially.

The angle-voltage conversion unit 132 outputs a control voltage Vct1 corresponding to the target angle command based on the detection characteristics of the angle detection unit 18. Specifically, sensitivity α and offset β are stored as detection characteristics of the angle detection unit 18 in the angle-voltage conversion condition storage unit 133, and the angle-voltage conversion unit 132 stores the angle-voltage conversion condition storage. The sensitivity α and the offset β are read from the unit 133, and the control voltage Vct1 is calculated based on the following equation (3). The sensitivity α and the offset β are used to generate the control voltage Vct1 so that feedback control can be performed using the detection voltage Vd.
Vct1 = αθ + β (3)
The angle-voltage conversion condition storage unit 133 stores therein a conversion table that defines the relationship between the target angle of the mirror unit 110 and the control voltage Vct1, and the target angle of the mirror unit 110 is based on this conversion table. May be converted into a control voltage Vct1.

  The subtracting unit 134 subtracts the voltage value of the detection voltage Vd from the voltage value of the control voltage Vct1, calculates a differential voltage Vs between the control voltage Vct1 and the detection voltage Vd, and outputs the differential voltage Vs to the drive signal generation unit 135. Output.

  The drive signal generator 135 outputs a second drive signal 62 in which the current value is increased or decreased according to the differential voltage Vs. That is, in the case of the positive polarity of the differential voltage Vs, the second drive signal 62 having a voltage value increased by a value proportional to the signal level of the differential voltage Vs is generated. A second drive signal 62 having a voltage value lowered by a value proportional to the signal level of the voltage Vs is generated. The drive signal generator 135 is configured by, for example, a PID controller that performs integration of the differential voltage Vs, and can generate the second drive signal 62 so that the differential voltage Vs approaches zero. In this manner, the optical scanning element 91 is driven by the second drive signal 62 having a voltage value corresponding to the differential voltage Vs to perform feedback control, and thereby the oscillation of the mirror unit 110 of the optical scanning element 91 is accurately performed. Like to do. The second scanning drive circuit 93 swings the mirror unit 110 in a non-resonant state by supplying a drive current having a current value corresponding to the voltage value of the second drive signal 62 to the coil 116 of the optical scanning element 91. Swing around the axis Ly.

  As described above, the second scanning unit controller 122 drives the second optical scanning element 91 based on the detection voltage Vd of the angle detection unit 18 so that the angle θ of the mirror unit 110 accurately matches the target angle. Feedback control.

  Furthermore, the control unit 10 includes a comparison unit 138 and a calibration processing unit 137, detects the relationship between the detection voltage Vd and the angle of the mirror unit 110, and outputs the second drive signal 62 based on the detection result. It is trying to generate.

  The comparison unit 138 receives the detection signal 99 output from the light detection unit 97, compares the detection signal 99 with the first threshold value and the second threshold value, and outputs the first detection signal and the second detection signal. That is, the comparison unit 138 outputs a first detection signal when the detection signal 99 having a voltage value equal to or higher than the second threshold is input, and the detection signal 99 having a voltage value equal to or higher than the first threshold and lower than the second threshold. When input, the second detection signal is output.

  The calibration processing unit 137 receives the detection voltage Vd output from the angle detection unit 18, the second drive signal 62, and the detection signal output from the comparison unit 138.

  When the calibration processing unit 137 determines that the first detection signal is input from the comparison unit 138, the calibration processing unit 137 stores the detection voltage Vd input at this time as the first calibration voltage Vd1. When the calibration processing unit 137 determines that the second detection signal is input from the comparison unit 138, the calibration processing unit 137 stores the detection voltage Vd input at this time as the second calibration voltage Vd2.

  The calibration processing unit 137 obtains the sensitivity α and the offset β that are the detection characteristics of the angle detection unit 18 based on the first calibration voltage Vd1 and the second calibration voltage Vd2 stored as described above. Specifically, the calibration processing unit 137 obtains the sensitivity α and the offset β by substituting the first calibration voltage Vd1 and the second calibration voltage Vd2 into the above formulas (1) and (2) as parameters. . Thereafter, the calibration processing unit 137 stores the obtained sensitivity α and offset β in the angle-voltage conversion condition storage unit 133. When the angle-voltage conversion unit 132 uses a conversion table that defines the relationship between the target angle of the mirror unit 110 and the control voltage Vct1, the calibration processing unit 137 generates the conversion table and converts the angle-voltage conversion. Store in the condition storage unit 133.

[6. Operation of control unit 10]
The operation of the control unit 10 configured as described above will be specifically described with reference to FIGS. 14 and 15.

  The control unit 10 starts activation based on a user operation on an operation unit (not shown). As shown in FIG. 14, when the control unit 10 starts to start, first, it performs start control (step S10). In this activation control, the mirror part 82a of the first optical scanning element 81 is oscillated around the oscillation axis Lx in a resonance state, and the mirror part 110 of the second optical scanning element 91 is oscillated in a sawtooth shape around the oscillation axis Ly. The scanning unit 30 is allowed to scan with laser light corresponding to the image signal S from the light source unit 20.

  Next, the controller 10 determines whether or not there is a calibration request (step S11). For example, the control unit 10 determines that a calibration request has been made when a predetermined operation is performed on an operation unit (not shown) by the user. If it is determined in this process that there is no calibration request (step S11: No), steady control is performed (step S12). In this steady control, for example, when an image signal S is input, image display processing is performed. The image display process outputs drive signals 60r, 60g, and 60b, which are elements for forming an image according to the image signal S, and emits laser light having an intensity according to the image signal S from the light source unit 20, This is a process of forming an image by scanning with the scanning unit 30.

  On the other hand, if it is determined in step S11 that there is a calibration request (step S11: Yes), the control unit 10 performs a calibration process (step S13). This calibration process is a process shown in steps S21 to S30 in FIG. 15, and will be described in detail later.

  When the process of step S13 ends, the control unit 10 determines whether or not there is an end command (step S14). For example, the control unit 10 determines that an end command has been issued when the user performs a predetermined operation on an operation unit (not shown). In this process, if it is determined that there is an end instruction (step S14: Yes), the process ends. On the other hand, if it is determined that there is no end instruction (step S14: No), the process proceeds to step S11.

  Next, the calibration process in step S13 will be specifically described with reference to FIG.

  First, the control unit 10 gradually increases the angle of the mirror unit 110 from the equilibrium position 0 until it exceeds + θy3 (see FIG. 3) (step S21). Specifically, the target angle command generation unit 131 sequentially reads information on the first signal waveform for calibration stored in the internal storage unit as information on the target angle from the storage unit, and sends it to the angle-voltage conversion unit 132. Output. The first signal waveform for calibration is a signal waveform for rotating the mirror unit 110 so that the angle of the mirror unit 110 gradually increases toward the + θ side until the angle of the mirror unit 110 exceeds + θy3. Note that if the signal level of the first signal waveform does not start from 0 but starts from a signal level that is so large that the angle of the mirror unit 110 does not become + θy3, detection until step S23 described later is performed. Can be shortened.

  Moreover, the control part 10 emits a laser beam from the light source part 20 (step S22). Specifically, the RGB laser controller 121 transmits predetermined drive signals 60r, 60g, and 60b to the laser drivers 66, 67, and 68, respectively. The control unit 10 emits laser light from the light source unit 20 until the angle of the mirror unit 110 exceeds the equilibrium position 0 to + θy3. However, when the angle of the mirror unit 110 becomes + θy3, the laser beam is emitted. If the laser beam can be emitted, the laser beam may be emitted after the operation of increasing the angle of the mirror unit 110 from 0 to + θ is started. In particular, by appropriately setting + θy3, the laser beam can be emitted from the light source unit 20 only when the scanning position of the second scanning unit 90 is in the invalid scanning range Yb1, and the user wears the RSD1. Even if it remains as it is, incidence on the user's eye 101 can be prevented. Therefore, it is possible to prevent the user from feeling uncomfortable.

  Next, it is determined whether or not the first detection signal is output (step S23). Specifically, the comparison unit 138 outputs the first detection signal when the detection signal 99 output from the light detection unit 97 has a voltage value equal to or higher than the second threshold value. The calibration processing unit 137 determines whether or not the first detection signal is output from the comparison unit 138. That is, whether the angle of the mirror unit 110 is + θy3, the laser light from the light source unit 20 is incident on the light detection unit 97, and the detection signal 99 having a voltage value equal to or greater than the second threshold value is output from the light detection unit 97. Determine whether or not. In this process, when it is determined that the first detection signal is not output (step S23: No), the control unit 10 waits until the first detection signal is output, and when the first detection signal is output (step S23). S23: Yes), information on the first calibration point is acquired (step S24). Specifically, as information on the first calibration point, the control unit 10 acquires the detection voltage Vd output from the angle detection unit 18 as the first calibration voltage Vd1, and sets the voltage value of the second drive signal 62 to the first value. Obtained as 1 voltage Vb1.

  Next, the control unit 10 gradually increases the angle of the mirror unit 110 from the equilibrium position 0 until it exceeds −θy3 (see FIG. 3) (step S25). Specifically, the target angle command generation unit 131 sequentially reads information on the second signal waveform for calibration stored in the internal storage unit as information on the target angle from the storage unit, and sends it to the angle-voltage conversion unit 132. Output. The second signal waveform is a signal waveform for rotating the mirror unit 110 so that the angle of the mirror unit 110 gradually increases to the −θ side until the angle of the mirror unit 110 exceeds −θy3. Note that if the signal level of the second signal waveform does not start from 0 but starts from a signal level that is such that the angle of the mirror unit 110 does not become −θy3, in step S27 described later. The time until the detection of can be shortened.

  Moreover, the control part 10 emits a laser beam from the light source part 20 (step S26). Specifically, the RGB laser controller 121 transmits predetermined drive signals 60r, 60g, and 60b to the laser drivers 66, 67, and 68, respectively. The control unit 10 emits laser light from the light source unit 20 until the angle of the mirror unit 110 exceeds −θy3 from the equilibrium position 0, but when the angle of the mirror unit 110 is −θy3, the laser is emitted. If the light can be emitted, the laser beam may be emitted after the operation of increasing the angle of the mirror unit 110 from 0 to −θ side is started. In particular, by appropriately setting −θy3, the laser beam can be emitted from the light source unit 20 only when the scanning position of the second scanning unit 90 is in the invalid scanning range Yb2, and the user wears the RSD1. Even if it continues, it can prevent injecting into a user's eye 101. FIG. Therefore, it is possible to prevent the user from feeling uncomfortable.

  Next, it is determined whether or not the second detection signal has been output (step S27). Specifically, the comparison unit 138 outputs a second detection signal when the detection signal 99 output from the light detection unit 97 is equal to or higher than the first threshold and lower than the second threshold. The calibration processing unit 137 determines whether or not the second detection signal is output from the comparison unit 138. That is, when the angle of the mirror unit 110 becomes −θy3, the laser light from the light source unit 20 enters the light detection unit 97, and the detection signal is greater than the first threshold and lower than the second threshold from the light detection unit 97. It is determined whether 99 is output. In this process, when it is determined that the second detection signal is not output (step S27: No), the control unit 10 waits until the second detection signal is output, and when the second detection signal is output (step S27). S27: Yes), information on the second calibration point is acquired (step S28). Specifically, as information on the second calibration point, the control unit 10 acquires the detection voltage Vd output from the angle detection unit 18 as the second calibration voltage Vd2, and sets the voltage value of the second drive signal 62 to the first value. Obtained as 2 voltage Vb2.

  Next, the control unit 10 estimates a straight line from the information of the two calibration points, and determines the sensitivity α and the offset β (step S29). Specifically, the calibration processing unit 137 of the control unit 10 determines the sensitivity α and the offset β based on the equations (1) and (2) from the first calibration voltage Vd1 and the second calibration voltage Vd2. .

  Thereafter, the control unit 10 updates the determined sensitivity α and offset β (step S30), and ends the calibration point acquisition process. Specifically, the calibration processing unit 137 of the control unit 10 stores the sensitivity α and the offset β in the angle-voltage conversion condition storage unit 133.

  As described above, in the RSD 1, when a calibration request is made, the relationship between the detection voltage Vd and the angle θ of the mirror unit 110 is detected and the calibration is performed. Therefore, the angle of the mirror unit 110 is set to a desired value. The angle can be controlled with high accuracy. The calibration request may be generated at a predetermined timing.

[7. Modification 1]
In the above-described embodiment, the laser light incident on the light detection unit 97 in the second optical path is reflected and transmitted by the half mirror 98 after branching from the first optical path, so that its intensity is ¼ or less. Become. Therefore, it is possible to prevent the strength from being lowered by using the polarizing plate.

  Here, an example using a polarizing plate is shown in FIG. In this example, a first λ / 4 plate 44 is provided on the optical path between the half mirror 98 and the first and second reflecting portions 41 and 42, and on the optical path between the half mirror 98 and the optical member 43. A second λ / 4 plate 45 is provided on the front side. The half mirror 98 is a polarization beam splitter whose reflectance is determined by the polarization state of incident light, and reflects S-polarized light and transmits P-polarized light. Then, laser light including P-polarized light and S-polarized light is incident on the half mirror 98 via the optical fiber cable 50.

  In the first optical path, as shown in FIG. 17, the S-polarized component of the laser light is incident on the light detection unit 97.

  On the other hand, in the second optical path, as shown in FIG. 17, the P-polarized component of the laser light emitted from the light source unit 20 passes through the half mirror 98 and passes through the first λ / 4 plate 44. The light is converted into λ / 4 circularly polarized light and is incident on the first and second reflecting portions 41 and 42. Then, since the laser light reflected by the first and second reflecting portions 41 and 42 passes through the first λ / 4 plate 44 again, it is converted into S-polarized linearly polarized light, and is reflected on the half mirror 98. Incident. At this time, since the laser light incident on the half mirror 98 is a laser light having only the S-polarized component, all of the light is reflected by the half mirror 98 and incident on the second λ / 4 plate 45 to be again circularly polarized. And is incident on the optical member 43. The laser beam incident on and reflected by the optical member 43 is converted into P-polarized linearly polarized light by being incident on the second λ / 4 plate 45 and incident on the half mirror 98. At this time, since the laser light incident on the half mirror 98 is a laser light having only a P-polarized component, the laser light passes through the half mirror 98 without being reflected and enters the light detection unit 97.

  As described above, in the configuration of the present modification, in the second optical path, half of the laser light is reflected by the half mirror 98 and there is no loss due to transmission of the half, so that power consumption can be suppressed. Further, in the light detection unit 97, it is possible to increase the difference in the signal level of the detection signal between when the laser light of only the first optical path is incident and when the laser light of the first optical path and the second optical path are simultaneously incident. And can be easily distinguished.

[8. Modification 2]
In the above description, the RSD 1 detects the relationship between the detection voltage Vd and the angle θ of the mirror unit 110 according to the calibration request. However, the signal level of the second drive signal 62 and the angle θ of the mirror unit 110 are detected. The relationship may also be detected.

  That is, when the control unit 10 determines that the scanning position of the second scanning unit 90 is + Y3 based on the detection signal 99 from the light detection unit 97, the voltage value of the second drive signal 62 at this time is set to the first voltage Vb1. If it is determined that the scanning position of the second scanning unit 90 is -Y3, the voltage value of the second drive signal 62 at this time is stored as the second voltage Vb2.

By doing so, the control unit 10 can grasp the relationship between the signal level (voltage value Vb) of the second drive signal 62 and the angle of the mirror unit 110 based on the detection signal 99 from the light detection unit 97. it can. That is, the relationship between the signal level of the second drive signal 62 and the angle θ of the mirror unit 110 can be derived as shown in FIG. 18 based on the first voltage Vb1 and the second voltage Vb2.
In the figure,
α ′ = (Vb1−Vb2) / 2θ3 (4)
β ′ = (Vb1 + Vb2) / 2 (5)
It is.

  Thus, the control unit 10 can detect the relationship between the signal level of the second drive signal 62 and the angle of the mirror unit 110 based on the detection signal 99 from the light detection unit 97, and this relationship and the detection voltage. By generating the control voltage Vct1 based on the relationship between Vd and the angle of the mirror unit 110, the angle of the mirror unit 110 can be controlled at a desired angle.

  Specifically, the calibration processing unit 137 shows the sensitivity indicating the relationship between the signal level of the second drive signal 62 and the angle θ of the mirror unit 110 based on the first voltage Vb1 and the second voltage Vb2 stored as described above. α ′ and offset β ′ are obtained. That is, the calibration processing unit 137 obtains the sensitivity α ′ and the offset β ′ by substituting the first voltage Vb1 and the second voltage Vb2 into the equations (4) and (5) as parameters, and determines the angle / level. Information is stored in a voltage correction condition storage unit (not shown). The angle-voltage conversion unit 132 reads the sensitivity α and the offset β from the angle-voltage conversion condition storage unit 133, and further reads the sensitivity α ′ and the offset β ′ from the voltage correction condition storage unit. The angle-voltage conversion unit 132 can generate the control voltage Vct1 from the sensitivities α and α ′ offsets β and β ′. If the relationship between the detection voltage Vd and the angle of the mirror unit 110 is constant, the angle-voltage conversion condition storage unit 133 is not necessary, and the angle-voltage conversion unit 132 is controlled from the sensitivity α ′ offset β ′. A voltage Vct1 is generated.

  In the above description, the light detection unit 97 is disposed at a position where the laser beam scanned by the scanning unit 30 is incident when the scanning position of the first scanning unit 80 is + X3. The light detection unit 97 may be arranged at a position where the laser beam scanned by the scanning unit 30 is incident when X is X0. In this way, the calibration process can be performed regardless of the operation of the first scanning unit 80.

  In addition, although the detection part which detects the angle of the mirror part of an optical scanning element is comprised by the piezoresistive element, you may use the detection method by the detection method by a piezoelectric element, or a capacitance change.

  In the above description, the detection voltage Vd and the angle θ of the mirror unit 110 are in a proportional relationship, and the signal level of the second drive signal 62 and the angle θ of the mirror unit 110 are in a proportional relationship. Are not necessarily in a proportional relationship, and the present invention can be applied as long as they have a certain relationship.

  The first reflecting portion 41 and the second reflecting portion 42 have the same length in the second direction as the diameter of the light beam and the same length in the first direction as the scanning range by the first scanning portion 80. However, it may be stretched parallel to the first direction. By doing in this way, the 1st reflection part 41 and the 2nd reflection part 42 can be made into the minimum magnitude | size.

  In the above description, the reflectance and transmittance of the half mirror 98 have been described as 1: 1. However, the reflectance and the transmittance are not necessarily equal.

  Although the present invention has been described through the above-described embodiments, the following effects can be expected according to this embodiment.

(1) The first scanning unit 80 that scans the light beam emitted from the light source unit 20 in the first direction X and the mirror unit 110 having the reflecting surface 110a are swung around the swing axis Ly, and the first scanning unit 80 is scanned. The second scanning unit 90 that scans the light beam scanned in the second direction Y substantially orthogonal to the first direction X, and a half provided on the optical path between the first scanning unit 80 and the second scanning unit 90 A mirror 98, a light detection unit 97 that detects the intensity and timing of a light beam scanned at a predetermined position in the first direction X by the first scanning unit 80 and reflected by the half mirror, and a first detection unit 97; The first reflection unit 41 and the second reflection unit 42 that are arranged at the image plane position formed by the light beam scanned by the two scanning unit 90 and reflect the light beam scanned by the second scanning unit 90, respectively, and the first scanning Scanned to a predetermined position in the first direction X by the unit 80 The first scanning unit 80 scans the optical path (second optical path) of the light beam reflected by the first reflecting unit 41 and the second reflecting unit 42 and reflected by the half mirror 98 to a predetermined position in the first direction X. The drive signals 61 and 62 are supplied to the optical member 43 and the first scanning unit 80 and the second scanning unit 90, respectively, which are incident on the light detection unit as the same optical path as the optical path (first optical path) of the light beam reflected by the half mirror 98. And the first scanning unit 80 and the second scanning unit 90 are controlled, and the scanning position of the first scanning unit 80 is detected based on the timing at which the light detection unit 97 detects the light flux, and the image signal S is detected. And a control unit 10 that emits a corresponding light beam from the light source unit 20. Therefore, it is necessary to provide a detection unit for each scanning unit of the mirror unit for detecting an angle around the swing axis of the mirror unit for each scanning unit. There is no.

(2) The angle detection unit 18 that detects an angle around the swing axis Ly of the mirror unit 110 is provided, and the control unit 10 controls the second scanning unit 90 to change the light beam emitted from the light source unit 20 to the first level. The information on the angle of the mirror unit 110 detected by the angle detection unit 18 when the light detection unit 97 detects a light beam having a predetermined intensity or more is incident on the reflection unit 41 and reflected, and the first calibration point information ( The first process acquired as the first calibration voltage Vd1) and the second scanning unit 90 are controlled so that the light beam emitted from the light source unit 20 is incident on the second reflecting unit 42 and reflected, and the light detecting unit A second process of acquiring information on the angle of the mirror unit 110 detected by the angle detection unit 18 as second calibration point information (second calibration voltage Vd2) when a light beam having a predetermined intensity or more is detected by 97; , Information of the first calibration point and the second calibration And the third processing for calibrating the detection result of the angle detection unit 18 based on the information of the mirror unit. Therefore, even if the angle detection characteristic of the mirror unit 110 by the angle detection unit 18 varies, the mirror unit The angle of 110 can be controlled at a desired angle with high accuracy.

(3) The mirror unit 110 of the second scanning unit 90 rotates at an angle corresponding to the signal level of the second drive signal 62, and the control unit 10 has an angle about the swing axis Ly of the mirror unit 110. Angle / level information (sensitivity α ′ and offset β ′) that defines the relationship between the signal level and the signal level of the second drive signal 62 is stored in an internal storage unit (angle-voltage conversion condition storage unit 133). The signal level (first voltage Vb1) of the second drive signal 62 when the information of one calibration point is acquired, and the signal level (second voltage Vb2) of the second drive signal 62 when the information of the second calibration point is acquired. ), The angle / level information (sensitivity α ′ and offset β ′) is corrected. Therefore, the relationship between the second drive signal 62 and the angle around the swing axis Ly of the mirror unit 110 can be easily specified. Can do.

(4) The reflectance of the light beam by the first reflection unit 41 is different from the reflectance of the light beam by the second reflection unit 42, and the first reflection unit 41 and the second reflection unit 42 are set in the second direction Y in a predetermined manner. Therefore, from the detection result of the angle detector 18, the first calibration point information (first calibration voltage Vd1) and the second calibration point information (second calibration voltage Vd2) are obtained. A distinction can be made easily.

(5) Since it has the lens 95a which comprises the telecentric optical system which injects the light beam scanned by the 2nd scanning part 90, and an image surface position is formed of the lens 95a, the 1st reflection part 41 and the 2nd reflection Since there may be some errors in the installation position of the reflecting surface of the portion 42 in the optical axis direction, a configuration that reflects the light beam in the direction opposite to the incident direction can be easily created.

(6) On the optical path between the first λ / 4 plate 44 provided on the optical path between the half mirror 98 and the first and second reflecting portions 41, 42, and the half mirror 98 and the optical member 43. The half mirror 98 is a polarization beam splitter whose reflectivity is determined by the polarization state of incident light, and is emitted from the light source unit 20 and passes through the half mirror 98. The incident light flux is incident on the first and second reflecting portions 41 and 42 via the first λ / 4 plate 44, and the light flux reflected by the first and second reflecting portions 41 and 42 is converted into the first λ / 4 plate 44, second λ / 4 plate 45, optical member 43, and second λ / 4 plate 45 are sequentially incident on the light detection unit 97, so that the loss of the light beam incident on the light detection unit 97 is reduced. Therefore, the light detection unit 97 can detect the light flux with high accuracy.

(7) The control unit 10 has the light source unit 20 at a timing at which the light beam emitted from the light source unit 20 does not enter the first reflection unit 41 and the second reflection unit 42 (for example, the effective scanning range Ya in the second direction Y). At this time, based on the detection timing of the light detection unit 97, the scanning position of the first scanning unit 80 is detected, and the light source unit 20 emits the light beam corresponding to the image signal S from the light source unit 20. Therefore, the detection of the scanning position of the first scanning unit 80 can be made different from the timing at which the information of the first calibration point and the information of the second calibration point is acquired, and the processing load due to performing each processing simultaneously is reduced. can do.

(8) The light shielding unit 96 includes a light shielding unit 96 that blocks the passage of the light beam scanned in the invalid scanning range W outside the effective scanning range Z for scanning the light beam having the intensity corresponding to the image signal S. The control unit 10 is located downstream of the reflection unit 41 and the second reflection unit 42, and the control unit 10 detects the light detection unit when the scanning position by the first scanning unit 80 and the second scanning unit 90 is in the invalid scanning range W. Since the light beam detected at 97 is emitted from the light source unit, it is possible to prevent the light beam emitted from the light source unit 20 from being emitted to calibrate the detection result of the angle detection unit 18.

(9) When the first processing and the second processing are performed, the control unit 10 stops the scanning of the first scanning unit 80, so that the calibration processing is performed regardless of the operation of the first scanning unit. Can do.

(10) A light beam having an intensity corresponding to the image signal S is scanned by the first scanning unit 80 and the second scanning unit 90 and is incident on the user's eye 101, and the image signal S is received on the user's retina 101b. Since the image is projected, the retinal scanning type image that can control the angle of the mirror unit 110 at a desired angle with high accuracy even when the angle detection characteristic of the mirror unit 110 is changed by the angle detection unit 18. A display device can be provided.

1 RSD
DESCRIPTION OF SYMBOLS 10 Control part 18 Angle detection part 20 Light source part 30 Scan part 41 1st reflection part 42 2nd reflection part 43 Optical member 44 1st (lambda) / 4 board 45 2nd (lambda) / 4 board 80 1st scanning part 90 2nd Scan unit 95a Lens (telecentric optical system)
96 light-shielding part 97 light detection part 98 1st half mirror 110 mirror part X 1st scanning direction Y 2nd scanning direction Vd1 1st voltage for calibration (information of 1st calibration point)
Vd2 Second calibration voltage (information of second calibration point)
Vb1 first voltage Vb2 second voltage

Claims (10)

A first scanning unit that scans a light beam emitted from the light source unit in a first direction;
A second scanning unit that scans a light beam scanned by the first scanning unit in a second direction substantially orthogonal to the first direction by swinging a mirror unit having a reflecting surface around a swing axis;
A half mirror provided on an optical path between the first scanning unit and the second scanning unit;
A light detector that detects the intensity and timing of a light beam that is scanned at a predetermined position in the first direction by the first scanning unit and that is reflected by the half mirror; and
A first reflecting portion and a second reflecting portion, which are disposed at an image plane position formed by the light beam scanned by the second scanning unit and respectively reflect the light beam scanned by the second scanning unit;
The first scanning unit scans a predetermined position in the first direction, is reflected by the first reflecting unit and the second reflecting unit, and is reflected by the half mirror. An optical member that is scanned into a predetermined position in the first direction by a scanning unit and is incident on the light detection unit as the same optical path as a light beam reflected by the half mirror;
Based on the timing at which the first scanning unit and the second scanning unit are respectively output by driving signals to the first scanning unit and the second scanning unit to control the first scanning unit and the second scanning unit, and the light detection unit detects the luminous flux. An image display apparatus comprising: a control unit that detects a scanning position of the first scanning unit and emits a light beam corresponding to the image signal from the light source unit. An angle detection unit for detecting an angle around the swing axis of the mirror unit;
The controller is
The second scanning unit is controlled to cause the light beam emitted from the light source unit to be incident and reflected on the first reflecting unit, and when the light detecting unit detects a light beam having a predetermined intensity or more, the angle is set. A first process for acquiring information on the angle detected by the detection unit as information on a first calibration point;
The light beam emitted from the light source unit is controlled by the second scanning unit to be incident on and reflected by the second reflection unit, and the angle when the light detection unit detects a light beam having a predetermined intensity or more. A second process of acquiring information on the angle detected by the detection unit as information on a second calibration point;
2. The image according to claim 1, wherein a third process of calibrating a detection result of the angle detection unit is executed based on the information on the first calibration point and the information on the second calibration point. Display device. The mirror part of the second scanning part rotates at an angle corresponding to the signal level of the drive signal,
The controller is
It has angle / level information that defines the relationship between the angle around the swing axis of the mirror part and the signal level of the drive signal,
The angle / level information is corrected based on the signal level of the driving signal when the information of the first calibration point is acquired and the signal level of the driving signal when the information of the second calibration point is acquired. The image display device according to claim 2. The reflectance of the light flux by the first reflecting portion is different from the reflectance of the light flux by the second reflecting portion, and the first reflecting portion and the second reflecting portion are set in a predetermined direction in the second direction. The image display device according to any one of claims 1 to 3, wherein the image display device is arranged at a distance. A telecentric optical system for entering the light beam scanned by the second scanning unit;
The image display apparatus according to claim 1, wherein the image plane position is formed by the telecentric optical system. A first λ / 4 plate provided on an optical path between the half mirror and the first and second reflectors;
A second λ / 4 plate provided on the optical path between the half mirror and the optical member,
The half mirror as a polarization beam splitter whose reflectivity is determined by the polarization state of the incident light beam,
The light beam emitted from the light source unit and passed through the half mirror is incident on the first and second reflection units via the first λ / 4 plate, and is reflected by the first and second reflection units. The light beam is incident on the light detection unit through the first λ / 4 plate, the second λ / 4 plate, the optical member, and the second λ / 4 plate in order. Item 6. The image display device according to any one of Items 1 to 5. The controller is
The light beam emitted from the light source unit is emitted from the light source unit at a timing at which the light beam does not enter the first reflection unit and the second reflection unit, and at this time, based on the detection timing of the light detection unit, The image display device according to claim 1, wherein a scanning position of the first scanning unit is detected, and a light beam corresponding to the image signal is emitted from the light source unit from the light source unit. . A light-shielding portion that blocks passage of a light beam scanned in an invalid scanning range outside an effective scanning range that scans a light beam having an intensity corresponding to the image signal;
The light shielding portion is located downstream of the first reflecting portion and the second reflecting portion,
The controller is
The light source detected by the light detection unit is emitted from the light source unit when a scanning position by the first scanning unit and the second scanning unit is in the invalid scanning range. The image display device according to any one of the above. The controller is
9. The image display device according to claim 1, wherein when the first process and the second process are performed, scanning of the first scanning unit is stopped. 10.   A light beam having an intensity corresponding to the image signal is scanned by the first scanning unit and the second scanning unit and incident on a user's eye, and an image corresponding to the image signal is projected onto the user's retina. The image display device according to claim 1, wherein:

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