JP2020095114A - Optical scanner and optical scanning method - Google Patents

Abstract

To perform satisfactory display of an image or imaging in an optical scanner.SOLUTION: An optical scanner 1 comprises: a light guide path that guides incident light and emits emission light from an emission end; a vibration unit that vibrates the emission end so that the emission end repeatedly draws a predetermined scanning locus; a light emission control unit 22 that controls emission of the emission light; a light detector that detects part of the emission light; a scanning coordinate creation unit that creates scanning coordinates related to the predetermined locus; a driving signal generation unit 20 that generates a sine wave with a modulated amplitude as a driving signal for driving the vibration unit corresponding to the scanning coordinates; and a coordinate calculation unit that calculates the coordinates of an image by using the scanning coordinates and outputs the coordinates as image coordinates. At least one of the radius of the image coordinates and the declination of the image coordinates depends on the radius of the scanning coordinates and the declination of the scanning coordinates.SELECTED DRAWING: Figure 1

Description

The present invention relates to an optical scanning device and an optical scanning method.

Along with the downsizing of video devices, downsizing and performance improvement of optical scanning devices are required. As a technique related to this, there is Patent Document 1 in which a technique related to an optical fiber scanner is described.

Specifically, in Patent Document 1, "The optical scanning endoscope apparatus 10 detects the resonance frequency fr before scanning the object 100, and optically scans the detected object at the resonance frequency fr. This makes it possible to prevent performance deterioration due to deviation of the resonant frequency of the fiber due to individual differences in the device and changes over time, and to appropriately adjust the drive frequency.” There is a description.

JP, 2005-75685, A

As described above, the optical scanning device of Patent Document 1 detects a resonance frequency to acquire an image. At this time, in order to display or pick up an excellent image, it is preferable to detect the resonance frequency without, for example, suspending the display or picking up of the image.
However, Patent Document 1 does not consider the technical means for displaying or picking up such an excellent image.

An object of the present invention is to display or pick up an excellent image in an optical scanning device.

An optical scanning device according to an aspect of the present invention is an optical scanning device that displays or images an image by using emitted light, and includes a light guide path that guides incident light to emit the emitted light from an emission end, and the emitted light. A vibrating section that vibrates the exit end so as to repeatedly draw a predetermined scanning locus, a light emission control section that controls the emission of the exit light, a photodetector that detects a part of the exit light, and the predetermined A scanning coordinate generation unit that generates scanning coordinates related to the locus; a driving signal generation unit that generates a sine wave whose amplitude is modulated as a driving signal for driving the vibrating unit corresponding to the scanning coordinates; A coordinate calculation unit that calculates the coordinates of the image using scanning coordinates and outputs the coordinates as image coordinates, and at least one of the radius of the image coordinates and the declination of the image coordinates is the radius of the scanning coordinates and It is characterized in that it depends on the deflection angle of the scanning coordinates.

An optical scanning device according to an aspect of the present invention is an optical scanning device that displays or images an image by using emitted light, and includes a light guide path that guides incident light to emit the emitted light from an emission end, and the emitted light. A vibrating section that vibrates the emitting end so that a predetermined scanning locus is repeatedly drawn, a light emission control section that controls emission of the emitted light, a photodetector that detects a part of the emitted light, and the vibrating section. A drive signal generation unit that generates a sine wave of which amplitude is modulated as a drive signal for driving the control unit, and a control unit that performs a predetermined control, the control unit displaying the image or the imaging Changing the drive parameter of the drive signal according to the detection signal detected by the photodetector during the optical scanning for performing the above.

An optical scanning method according to an aspect of the present invention includes a light guide path that guides incident light and emits the emitted light from an emission end, and a vibration that vibrates the emission end so that the emitted light repeatedly draws a predetermined scanning locus. Section, a light emission control section that controls the emission of the emitted light, a photodetector that detects a part of the emitted light, and a sine wave whose amplitude is modulated as a drive signal for driving the vibrating section. An optical scanning method for displaying or picking up an image by the emitted light by using an optical scanning device having a drive signal generating section for controlling and a control section for performing a predetermined control. During the step of starting display or image capturing and the period during which optical scanning for displaying or capturing the image is performed, it is possible to change the drive parameter of the drive signal using the detection signal detected by the photodetector. It is characterized in that a step of determining whether it is necessary and a step of instructing a change of a drive parameter of the drive signal according to a result of the determination are performed.

According to one aspect of the present invention, it is possible to display or capture an excellent image in the optical scanning device.

3 is a block diagram showing the configuration of the optical scanning device 1. FIG. 3 is a diagram showing a structure of an optical scanning unit 10. FIG. 3 is a diagram showing a structure of an optical scanning unit 10. 3A and 3B are diagrams illustrating a structure of a detector 110 and a light spot detected by the photodetector 110 during optical scanning. It is a differential signal when the phase of optical scanning is changed. FIG. 3 is a diagram showing a relationship with an illumination unit 11, a light receiving unit 12, and a demultiplexing unit 108. 3 is a block diagram showing the configuration of a drive signal generation unit 20. FIG. 5 is a diagram showing waveforms inside the drive signal generation unit 20. FIG. 3 is a block diagram showing a configuration of a remapping control unit 21. FIG. (A) is a figure explaining the case where the light emission control part 22 emits light normally, (b) is a figure explaining the case where the light emission control part 22 reduces brightness. It is a figure explaining the distortion of the projection image which arises in the case of a scanning locus. It is a figure explaining the projection image when changing the constant term C. 6 is a flowchart of a dot shift correction process in the optical scanning device 1. It is a figure which shows the gain (gain) of a secondary resonance system (gain), and the frequency characteristic of a phase. It is the figure which drew the scanning locus. 6 is a block diagram showing the configuration of a phase difference measuring unit 23. FIG. 6 is a diagram showing waveforms inside the phase difference measuring unit 23. FIG. 6 is a flowchart showing a process of the optical scanning device 1. 3 is a block diagram showing the configuration of the optical scanning device 2. FIG. 3 is a block diagram showing a configuration of a moving time measuring unit 24. FIG. It is a figure which shows a light spot. It is a figure which shows the value of the differential signal D1 and the differential signal D2 when changing the radius of a circular locus. It is a figure which shows an example of the scanning locus|trajectory of light. 6 is a flowchart showing a process of the optical scanning device 1. It is a figure which shows the structure at the time of mounting in a head mounted display. It is a figure which shows the light spot detected by the photodetector 110 during optical scanning. It is a figure which shows the simple differential signal and the differential signal when changing the phase of optical scanning. 3 is a diagram showing a structure of an optical scanning unit 13. FIG. 3 is a diagram showing a structure of an optical scanning unit 13. FIG. 3 is a cross-sectional view of a vibrating section 101. FIG. It is a figure which shows the structure and installation direction of the detector 110. It is a figure which shows the area|region on a locus. 3 is a diagram showing a structure of an optical scanning unit 17. FIG. 6 is a cross-sectional view of the optical scanning unit 17. FIG. 3 is a diagram showing a structure of an optical scanning unit 18. FIG. 3 is a block diagram showing a configuration of an optical scanning device 6. FIG. 3 is a diagram showing a structure of an optical scanning unit 19. FIG. It is a figure which shows the structure of the photodetector 115. It is a figure which shows the light-receiving surface of the photodetector 115. It is a figure which shows the light-receiving surface of the photodetector 115.

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

The configuration of the optical scanning device 1 according to the first embodiment will be described with reference to FIG. FIG. 1 is a block diagram showing an optical scanning device 1 including an optical scanning unit 10.

The optical scanning device 1 is a device having a function of projecting an image, such as a projector or a head mounted display. The optical scanning device 1 may be a device having a function of capturing an image, such as a camera or an endoscope.

The optical scanning device 1 includes an optical scanning unit 10, an illumination unit 11, a light receiving unit 12, a drive signal generation unit 20, a remapping control unit 21, a light emission control unit 22, a phase difference measurement unit 23, an amplification unit 30, a laser driver 31, A differential signal generation unit 32, a display image storage memory 33, a controller (control unit) 40, a storage unit 41, and an input/output control circuit 42 are provided.

The drive signal generation unit 20, the remapping control unit 21, the light emission control unit 22, and the phase difference measurement unit 23 are realized as a logic circuit by an FPGA (Field Programmable Gate Array), for example. Alternatively, it may be implemented by hardware such as an ASIC (Application Specific Integrated Circuit).

The optical scanning device 1 is connected to the external control device 50 via the input/output control circuit 42. The optical scanning device 1 has a function of receiving a video signal from the external control device 50 and displaying a video.

The controller 40 as a control unit controls each block of the optical scanning device 1. The controller 40 realizes its function by a central processing unit such as a CPU (Central Processing Unit). In FIG. 1, the signal lines from the controller 40 only show important lines for explanation, and not all of them are shown. For example, the remapping control unit 21 may also start or end the operation in response to an instruction from the controller 40, or may return a status to the controller 40.

The storage unit 41 stores information necessary for processing of each unit constituting the optical scanning device 1 including the controller 40 and generated information. The storage unit 41 is a storage device such as a RAM (Random Access Memory) or a flash memory, and functions as a storage area in which programs and data are temporarily read. The storage unit 41 includes an HDD (Hard Disk Drive), a CD-R (Compact Disc-Recordable), a DVD-RAM (Digital Versatile Disk-Random Access Memory), and an SSD (solid-state readable). It may be a storage medium, a storage medium drive device, or the like. The controller 40 is processed by the CPU that operates according to the program read on the storage unit 41.

The video signal received by the optical scanning device 1 via the input/output control circuit 42 is stored in the display image storage memory 33. The drive signal generation unit 20 generates a plurality of drive signals for scanning the light in the optical scanning unit 10 based on the instruction from the controller 40. The drive signal output from the drive signal generation unit 20 is amplified by the amplification unit 30 and applied to the actuator provided in the optical scanning unit 10. Thereby, the light is scanned.

The remapping control unit 21 calculates, based on the information from the drive signal generation unit 20, which pixel information at which coordinate should be turned on in the video information stored in the display image storage memory 33. The calculated coordinates (x _calc , y _calc ) are supplied to the display image storage memory 33, and the gradation data (R, G, B) of the pixel at the corresponding coordinates is supplied to the light emission control unit 22. The light emission control unit 22 generates a signal for controlling the light emission of the laser based on the gradation data of the pixel. Further, the light emission control unit 22 corrects the brightness based on the information from the drive signal generation unit 20. The signal generated by the light emission control unit 22 is supplied to the laser provided in the illumination unit 11 via the laser driver 31. The light emitted from the laser is applied to the projection surface via the optical scanning unit 10. Thereby, the light emission of the laser is controlled in synchronization with the scanning of light.

The differential signal generation unit 32 outputs a differential signal described below based on a signal from the photodetector 110 provided in the optical scanning unit 10. The phase difference measuring unit 23 measures the phase difference based on the output signal of the drive signal generating unit 20 and the differential signal output from the differential signal generating unit 32, and transmits it to the controller 40. The controller 40 gives an instruction to change the drive parameter of the drive signal generation unit 20 based on the measured phase difference, if necessary.

When an image is captured, the return light that has been emitted back to the target is guided to the light receiving unit 12 via the optical scanning unit 10. If the optical scanning device 1 does not have a photographing function, the light receiving unit 12 is not always necessary. Further, the light emission control unit 22 may have a function of notifying another circuit of the timing of light emission.

Next, the structure of the optical scanning unit 10 will be described with reference to FIG. 2A. The optical scanning unit 10 includes a vibrating unit 101, a light guide path 102, an adhesive unit 103, a lens 104, a housing 105, a supporting member 106, an electric wiring 107, a demultiplexing unit 108, a prism 109, and a photodetector 110. The demultiplexing unit 108 will be described later. In addition, the coordinate axes in this specification are also shown.

The vibrating section 101 is an actuator that generates vibration, and is, for example, a piezoelectric actuator, an electromagnetic actuator, or an electrostatic actuator. The vibrating portion 101 is configured by disposing a plurality of electrodes on the inner circumference or the outer circumference of a cylindrical piezoelectric element having a hollow central portion. The electrode provided on the vibrating portion 101 is connected to the electric wiring 107, and the vibrating portion 101 vibrates based on a drive signal applied through the electric wiring 107. The vibrating unit 101 is an actuator that can be displaced with respect to two axes, the x-axis and the y-axis.

A light guide path 102 is installed in the hollow portion of the vibrating section 101, and the vibrating section 101 and the light guide path 102 are fixed by an adhesive section 103. The vibrating section 101 is fixed to the housing 105 by the supporting member 106.

The light guide path 102 is, for example, a single mode or multimode optical fiber. The optical fiber includes a coat layer, a clad layer, and a core layer, and the light is confined in the core layer and propagates. An optical fiber from which the coat layer is peeled off may be used for the light guide path 102. As a result, the size of the optical scanning unit 10 can be reduced.

When capturing an image, the light guide path 102 captures the return light from the target. The return light is finally guided to the light receiving unit 12. The light guide path 102 may use a plurality of optical fibers or may use a multi-core type optical fiber in order to enhance the efficiency of returning light.

The lens 104 is a lens formed of glass or resin. The lens 104 is a spherical or aspherical lens, and may be a Fresnel lens or a gradient index GRIN (gradient index) lens. Further, the lens 104 may be integrated with the emission end 102a of the light guide path 102. Further, the lens 104 may be composed of a plurality of lenses instead of one lens.

The prism 109 is a prism that transmits a part of the light and deflects a part of the light at right angles to the incident direction. The prism 109 is arranged in front of the lens 104. In FIG. 2A, transmitted light is indicated by L1 and deflected light is indicated by L2. As for the ratio of the intensities of L1 and L2, the intensity of the light of L1 is higher, for example, L1:L2=9:1. The photodetector 110 detects the light L2 deflected by the prism 109.

The emission end 102a of the light guide path 102 projects like a cantilever with the adhesive portion 103 as a fixed end. When the vibrating portion 101 is vibrated, the emitting end 102a of the light guide path 102, which is the free end, resonates and vibrates. Due to this vibration, the light emitted from the light guide path 102 becomes the transmitted light L1 emitted through the lens 104 and the prism 109, and is irradiated on the target surface to perform light scanning.

FIG. 3 is a diagram showing a structure of the photodetector 110 and a light spot detected by the photodetector 110 during optical scanning. The photodetector is a quadrant detector.

As shown in FIG. 3A, split axes are arranged along the xz plane, and the split light-receiving surfaces are 110A, 110B, 110C, and 110D. Further, in the present specification, electric signals from the respective light receiving surfaces are represented by signals A, B, C and D. The photodetector 110 can switch a plurality of gain settings and may have a configuration capable of changing the amplification factor of an electric signal. The differential signal generation unit 32 performs the following operations (Equation 1) and (Equation 2) on these four signals, and outputs a first differential signal D1 and a second differential signal D2.

Here, since the denominator has a value corresponding to the total light amount, the differential signal of the first embodiment is a normalized signal.

Here, the meaning of the differential signal in the first embodiment will be described. FIG. 2B is a diagram for explaining the size of the light spot received by the photodetector 110.

The light exiting the lens 104 scans the range indicated by θFOV in the figure by the resonant oscillation of the exit end 102a of the light guide path 102. At this time, the ray diagram until the light emitted from the lens 104 reaches the photodetector 110 is as shown in FIG. 2B. SP0 and SP1 indicate the positions of the light spots detected by the photodetector 110 during the optical scanning. SP0 is a light spot when passing the center of the locus, and SP1 is a light spot when the locus of optical scanning passes in the positive y-axis direction. As can be seen from FIG. 2B, the light spot reaching the photodetector 110 has a large area.

Based on this, the meaning of the differential signal will be described with reference to FIG. SP1 and SP2 in FIG. 3 indicate the size of the light spot, and SP1-0 and SP2-0 indicate the center of the light spot.

In the present specification, for the sake of explanation, the origin of the xz plane is set at the center of the four-divided detector, and the deviation angle in the xz plane is referred to as the optical scanning phase. That is, FIG. 3A shows the case where the optical scanning phase is 90 degrees, and FIG. 3B shows the case where the optical scanning phase is 0 degrees. In the case of FIG. 3A, the light spot is bisected by the z axis. Therefore, the value of the first differential signal D1 becomes zero. Further, in the case of FIG. 3B, the light spot is divided into two equal parts by the x-axis, so that the value of the second differential signal D2 becomes zero.

In the first embodiment, it is assumed that the outer size of the photodetector 110 is the smallest square under the condition that the light spot at an arbitrary position on the optical scanning locus is received by the light receiving surface. Of course, the size of the photodetector 110 is not limited to this, and a larger size may be used.

The differential signal of the first embodiment will be described with reference to FIG. For the sake of explanation, the locus of optical scanning is assumed to be a circle centered on the origin, and the differential signal when the phase is changed is shown in FIG. FIG. 4A shows the value of the first differential signal D1, and FIG. 4B shows the value of the second differential signal D2. Therefore, the zero crossing of the differential signal occurs when the center of the light spot is located on the dividing line (that is, the x-axis or the z-axis) of the 4-division detector.

As described above, by detecting using the 4-division detector, it is possible to detect that the center of the light spot is located on the division line (that is, the x-axis or the z-axis) of the 4-division detector.

FIG. 5 is a diagram showing the relationship between the illumination unit 11, the light receiving unit 12, and the demultiplexing unit 108 in the optical scanning unit 10. The illumination unit 11 includes a light source unit 1101 and a multiplexing unit 1102. The light source unit 1101 has at least one or more light sources, and one or more lights emitted from the light sources are multiplexed by the multiplexing unit 1102, and the demultiplexing unit in the optical scanning unit 10 is passed through an optical fiber (not shown). It is guided to 108. The light source unit 1101 of this embodiment is equipped with a laser corresponding to each of the three primary colors of light, red, green, and blue, and a laser having an infrared wavelength, and a multiplexing unit 1102 guides an arbitrary color. To do.

The demultiplexing unit 108 has a function of guiding the light from the illumination unit 11 to the light guide path 102, and as a result, the light is emitted from the emission end 102 a of the light guide path 102. Further, the demultiplexing unit 108 guides the return light from the target captured in the light guide path 102 to the light receiving unit 12. The light receiving unit 12 corresponds to the light receiving unit of the camera and outputs information according to the intensity of the returning light from the target. The light receiving unit 12 is composed of, for example, a color filter, a lens, and a detector.

Subsequently, the configuration of the drive signal generation unit 20 according to the first embodiment will be described with reference to FIG.

The drive signal generation unit 20 includes a scanning coordinate generation unit 2001, a first sine wave generation unit 2002, a second sine wave generation unit 2003, a first amplitude modulation waveform generation unit 2004, and a second amplitude modulation waveform generation unit 2011. , A first variable gain 2005, a second variable gain 2006, a first multiplier 2007, a second multiplier 2008, a first inverting gain 2009 and a second inverting gain 2010. The drive signal generator 20 outputs four drive signals of VX1, VX2, VY1, and VY2.

The scanning coordinate generation unit 2001 generates coordinates of the scanning locus (hereinafter, referred to as scanning coordinates) so that the locus of the laser on the projection surface draws a predetermined locus. The scanning coordinates generated by the scanning coordinate generation unit 2001 are represented by the following (Equation 3) and (Equation 4).

The first sine wave generation unit 2002 generates the first sine wave S1 based on the angle θ _drv . The amplitude of the first sine wave output from the first sine wave generation unit 2002 is changed by the first variable gain 2005 and becomes the x-axis drive sine wave Sx. The magnification of the first variable gain 2005 is instructed by the controller 40.

The second sine wave generation unit 2003 generates a second sine wave S2 having a predetermined phase difference _{Δθ drv} with respect to the first sine wave based on the angle θ _drv and the command signal from the controller 40. .. Information on the phase difference _{Δθ drv} is instructed from the controller 40. The amplitude of the second sine wave output from the second sine wave generation unit 2003 is changed by the second variable gain 2006 and becomes the y-axis drive sine wave Sy. The magnification of the second variable gain 2006 is designated by the controller 40.

The first amplitude modulation waveform generation unit 2004 generates the amplitude modulation waveform S3 based on the radius r _x . The first multiplier 2007 multiplies the x-axis driving sine wave SX and the amplitude modulation waveform S3. The multiplied waveform becomes the signal Vx1, the amplitude is inverted by the first inversion gain 2009, and the inverted waveform becomes the signal Vx2.

Further, the second amplitude modulation waveform generation section 2004 generates the amplitude modulation waveform S4 based on the radius r _y . The second multiplier 2008 multiplies the y-axis drive sine wave SY and the amplitude modulation waveform S4. The multiplied waveform becomes the signal Vy1, and the amplitude is inverted by the second inversion gain 2010, and the inverted waveform becomes the signal Vy2.

In the first embodiment, the voltages Vx1, Vx2, Vy1 and Vy2 are amplified by the amplification unit 30 and become amplified drive signals Vdx1, Vdx2, Vdy1 and Vdy2. These amplified drive signals are applied to the electrodes provided on the vibrating section 101 in the optical scanning section 10. As described above, among the electrodes provided in the vibrating section 101, sine waves having different polarities are applied to the electrodes facing each other. Under this condition, it is assumed that the vibrating portion 101 is configured to be displaced in the axial direction shown in FIGS. 2A and 2B. Since the vibrating portion 101 is a piezoelectric element, the above configuration can be realized depending on the direction in which the piezoelectric element is polarized.

Further, the first sine wave S1 and the second sine wave S2 are output to the phase difference measuring unit 23. Further, the frequency f _{drv at which} the angle θ _drv rotates from 0 degree to 360 degrees is the main frequency component of the drive signal, and is referred to as the drive frequency in this specification. The drive frequency f _drv is instructed by the controller 40.

The drive circuit generation unit having this configuration can generate an arbitrary drive signal generated by a sine wave whose amplitude is modulated. The drive signal corresponds to the scan coordinates generated by the scan coordinate generation unit. In other words, the scanning coordinates are the coordinates of the scanning locus that can be calculated backward from the waveform of the drive signal. The amplitudes Rx and Ry generated by the scanning coordinate generation unit 2001 are expressed by the following (Equation 5) and (Equation 6) as a function of time. Here, a12 is a positive number.

That is, in the first embodiment, the x-axis is not amplitude-modulated. Further, the amplitude of the sine wave of the y-axis drive signal (envelope of the sine wave) monotonically increases. By controlling in this way, the scanning locus as shown in FIG. 7 can be drawn. That is, an elliptical locus having the same major axis is drawn.

Next, the configuration of the remapping control unit 21 according to the first embodiment will be described with reference to FIG.

The remapping control unit 21 includes an angle correction unit 2101 and a coordinate calculation unit 2102. The angle correction unit 2101 uses θ _drv , r _x , and r _y from the drive signal generation unit 20 to perform the following _formulas (7) and (8), and outputs the corrected angle θ _calc .

The coordinate calculation unit 2102 performs the operations of ( _Equation 9) and ( _Equation 10) below, and outputs x _calc and y _calc .

In the above equation, f _θ (), f _x (), and f _y () are functions having the amplitude r and the angle θ as arguments, and the functions are instructed by the controller 40. In this specification, these functions are collectively referred to as a distortion correction function. C is a constant. x _calc and y _calc are coordinate information for correcting the distortion of the projected image. As a result, of the video information stored in the display image storage memory 33, the gradation data of the pixel corresponding to the coordinates (x _calc , y _calc ) is read. The gradation data is information on the colors of pixels forming an image, and is, for example, 256 gradation data for each of the three primary colors of light, red, green, and blue. In this specification, the gradation value of each color is represented by R, G, B, and the gradation data is represented by (R, G, B). With the above configuration, the remapping control unit 21 and the display image storage memory 33 determine the laser emission data.

Then, operation|movement of the light emission control part 22 is demonstrated. The light emission control unit 22 in the first embodiment receives the gradation data (R, G, B) supplied from the display image storage memory 33, and controls the laser light emission based on it. Further, the light emission control unit 22 in the first embodiment has a function of correcting the brightness based on the scanning coordinates based on the instruction from the controller 40. Note that it is possible not to correct the brightness depending on the instruction from the controller 40.

The brightness correction in the first embodiment is performed by changing the laser lighting frequency. FIG. 9 is a diagram illustrating the operation of the light emission control unit 22 in the first embodiment. The horizontal axis represents time, and the vertical axis represents laser emission intensity. FIG. 9A shows a normal light emitting state. On the other hand, FIG. 9B shows the light emitting state when the brightness is reduced.

As shown in FIG. 9B, when the brightness is lowered, the emission intensity of the laser is not uniformly lowered, but the lighting frequency (duty) of the laser is lowered to lower the luminance. It is assumed that the blinking cycle in FIG. 9B is so fast that it cannot be visually recognized by human eyes. With the above configuration, the emission of the laser is controlled in synchronization with the scanning of light, and the luminance is made uniform regardless of the position of the image.

Here, the projected image in the case of the scanning locus of the first embodiment will be described. The projected image is large and has two characteristics. One is the dot shift above and below the major axis of the elliptical locus, and the other is the distortion of the projected image.

First, the dot shift will be described. Although there are distortions to be described later in the actual projected image, here, assuming that there is no distortion, only the dot shift will be described. The projected image when the constant term C of (Equation 8), which is the equation of the correction angle θ _calc , is changed will be described with reference to FIG. 11.

Note that f _θ () is a function that becomes zero under the condition that the image coordinates match the major axis of the elliptical locus. That is, the following (Equation 11) is established on the major axis of the elliptical locus.

Consider a case where a cross image as shown in FIG. 11A is projected as a projection image. It is assumed that the constant term C is set to the optimum value and the state shown in FIG. If C is increased by 10° from that state, the projected image becomes as shown in FIG. 11(b). When C is reduced by 10°, the projected image becomes as shown in FIG. Thus, the inventor has found the following points. (1) When the constant term C is changed, the image becomes discontinuous above and below the major axis of the elliptical locus. (2) Ideally, the constant term C is 90°.

Hereinafter, in this specification, this phenomenon is referred to as a dot shift. In addition, this dot shift causes discontinuity in the image and is easy to visually recognize, which causes discomfort. Therefore, it is necessary to perform correction with high accuracy.

This cause can be explained by considering the transfer function from the drive signal to the displacement of the light guide path 102. The emission end 102a of the light guide path 102 resonates and vibrates when the vibrating section 101 vibrates in response to a drive signal. Generally, the frequency characteristics of the gain and the phase of the secondary resonance system are as shown in FIGS. 13(a) and 13(b).

Here, consider a case where the resonance frequency of the cantilever composed of the light guide path 102 (hereinafter referred to as the resonance frequency of the light guide path 102) changes from f0 to f1 due to factors such as temperature. Here, first, consider the case where f1 is larger than f0. A state in which the resonance frequency of the light guide path 102 is f0 is referred to as a state 0, and a state in which the resonance frequency is changed to f1 is referred to as a state 1. 13A and 13B, the solid line shows the frequency characteristic of state 0, and the dotted line shows the frequency characteristic of state 1.

Here, in Example 1, the frequency characteristic of the secondary resonance system is a transfer function from the amplification drive signal to the displacement of the light guide path 102. In the first embodiment, there are two drive axes, x and y, but the x axis will be described here as an example. Further, there are two x-axis amplified drive signals of Vdx1 and Vdx2 in the first embodiment, but since these are signals whose amplitudes are only inverted, description will be made using Vdx1.

In the state 0, it is assumed that the frequency of the first sine wave S1 which is the frequency component of the amplified drive signal Vdx1 matches with f0. At this time, as indicated by a black circle, the displacement of the light guide path 102 becomes maximum and the phase difference becomes −90°. This means that the phase of displacement of the light guide path 102 in the x-axis direction is delayed by 90° with reference to the amplified drive signal Vdx1.

Here, a case where the state 1 is changed due to a factor such as temperature will be described. When the frequency of the first sine wave S1 remains f0, the displacement of the light guide path 102 is greatly reduced and deviates from the resonance state, as can be seen from the white circle in the gain characteristic. At this time, the phase becomes Δθ′, which is a value larger than −90.

When f1 is smaller than f0, the phase becomes a value smaller than −90°. From this, if the phase of the secondary resonance system can be measured, the frequency of the current amplification drive signal is larger or smaller than the resonance frequency depending on whether or not the value of the measured phase is larger than −90°. Can be determined. By utilizing this, it is possible to change the frequency of the amplified drive signal Vdx1 from f0 to f1. When the frequency of the amplified drive signal Vdx1 becomes equal to the resonance frequency f1 of the light guide path 102 in the state 1, the measured phase difference becomes −90°.

Here, in the first embodiment, description will be given below assuming that there is no factor such as a temperature change and the state 0 in which the resonance frequency of the light guide path 102 is f0 is maintained.

The phase difference of −90° in the resonance state is the phase of displacement of the light guide path 102 in the x-axis direction with reference to the amplified drive signal Vdx1. Considering the transfer function from the drive signal to the displacement of the light guide path 102, a value obtained by adding the delay d1 due to the electric circuit of the amplification unit in addition to the above-mentioned phase difference. In the present specification, for the sake of explanation, d1 is 10°. At this time, in the resonance state, the phase from the drive signal to the displacement of the light guide path 102 is −100°. That is, the optimum value of the constant term C is 100°. Further, when the constant term C deviates from the optimum value, the lighting timing deviates along the elliptical orbit, and therefore, it becomes as shown in FIG. 11B or FIG. 11C.

As described above, the correct image cannot be displayed unless the constant term C of the equation (8), which is the equation of the correction angle θ _calc , is set in consideration of the phase delay of the secondary resonance system and the delay due to the electric circuit. .. Furthermore, the phase may deviate from the above 100° due to factors such as temperature. Therefore, it is preferable to detect the dot shift from the actual light scanning locus and adjust the constant term C. Therefore, the optical scanning device 1 according to the first embodiment performs a dot shift correction process described later.

Next, the distortion of the projected image that occurs in the case of the scanning locus of the first embodiment will be described with reference to FIG. Here, it is assumed that the dot shift described above has been appropriately corrected. Consider a case where a video image as shown in FIG. 10A is projected as a projection image. FIG. 10A is an image composed of a plurality of concentric circles having different radii and a plurality of straight lines passing through the centers of the concentric circles and having different inclinations. Ideally, the same image as that in FIG. 10A is drawn on the projection surface. However, the image actually projected is distorted as shown in FIG.

The inventor has found that in the case of the scanning locus of Example 1, distortion depending on the image angle occurs. Specifically, as shown in FIG. 10B, the distortion f1 when the image coordinate declination is 30° and the distortion f2 when the image coordinate declination is 60° are different. As the declination angle approaches 180°, there is a characteristic that the distortion becomes smaller as indicated by f1, f2, f3, and f4. On the other hand, when the argument exceeds 180°, the distortion f1′ when the argument of the image coordinate is 210° is equal to the distortion f1 when the argument of the image coordinate is 30°. Similarly, f2 and f2' are equal. That is, the distortion of the image coordinate deviation angle θ [rad] is equal to the distortion of the image coordinate deviation angle θ + π [rad]. That is, the function f _θ (r, θ) is a periodic function of the period π [rad] with respect to θ.

Further, not only is there distortion such that the circle becomes an ellipse, but there is also distortion such that the ellipse extends in the axial direction as indicated by A and B on the major axis. Therefore, the functions f _x (r, θ) and f _y (r, θ) need to be functions of the radius r and the argument θ. As described above, when the amplitude modulation of the drive signal is different between the x-axis and the y-axis, dot deviation or distortion depending on the image angle of the period π [rad] occurs. This can be rephrased in that at least one of the radius of the image coordinates and the argument of the image coordinates depends on the radius of the scanning coordinates and the argument of the scanning coordinates.

The dot shift correction processing according to the first embodiment will be described. FIG. 12 shows a flowchart of the dot shift correction process in the optical scanning device 1 of the first embodiment.

When the optical scanning device 1 starts the dot shift correction process (step S1201), the controller 40 acquires the value of the differential signal at the designated timing (step S1202). Then, it is determined whether the value of the differential signal is zero (step S1203).

When the value of the differential signal is not zero (No in step S1203), the constant term C is changed (step S1204), and the process returns to step S1202. At this time, it is possible to determine whether the constant term C should be changed to a larger value or a smaller value depending on whether the value of the differential signal is positive or negative. Furthermore, it is also possible to calculate the amount by which the constant term C should be changed according to the value of the differential signal. If the value of the differential signal is zero (Yes in step S1203), the dot shift correction process ends (step S1205).

In this way, the dot shift is detected using the output signal of the detector 110, and the constant term C is changed to adjust it to the optimum value. This makes it possible to correct the dot shift with high accuracy and solve the image discontinuity.

As described above, according to the first embodiment, it is possible to properly display an image in the optical scanning device having a function of displaying an image.

Next, the configuration of the optical scanning device of the second embodiment will be described.
Although the first embodiment has a configuration in which an elliptical locus having the same major axis is drawn, the locus of optical scanning is not limited to this. Example 2 is an embodiment for realizing another optical scanning locus.

The configuration of the optical scanning device of the second embodiment is the same as that of the first embodiment, and the internal signal generated by the drive signal generation unit 26 is different. The amplitudes Rx and Ry generated by the scanning coordinate generation unit 2001 of the present embodiment are expressed by the following (Equation 12) and (Equation 13) as a function of time. Here, a11 is a negative number and a12 is a positive number.

That is, the amplitude of the sine wave of the drive signal (increase/decrease of envelope) is modulated such that when one of the x-axis and the y-axis of the substantially orthogonal orthogonally increases, the other decreases. By controlling in this way and inclining the axis at an angle of 45 degrees, a locus close to a rectangle is obtained as shown in FIG. By extending this in the lateral direction and causing the laser to emit light only when the scanning position is within the predetermined effective range A, it is possible to display an image with a rectangular aspect ratio like a general image format. The extension of the scanning range can be optically performed by disposing a lens or the like in front of the prism 109.

In the case where the amplitude of the sine wave of the drive signal (increase/decrease of the envelope) is modulated in such a manner that one of the x-axis and the y-axis, which are substantially orthogonal to each other, conversely increases and the other decreases Also, it was found that dot deviation, distortion depending on the image angle, and the like occur similarly to the case of the first embodiment.

This can be understood by drawing the scanning locus shown in FIG. 14A separately in the first half and the second half. FIG. 14B is a result of drawing the first half of the scanning locus, and FIG. 14C is a result of drawing the latter half of the scanning locus. Thus, unlike the case of the first embodiment, the length of the major axis of the ellipse is not constant, but the first half is a set of loci consisting of ellipses whose major axis is the angle 45°, and the latter half is long at the angle −45°. It is a set of loci consisting of ellipses as axes.

Therefore, also in the case of the second embodiment, the same distortion as in the first embodiment occurs. Therefore, similarly to the case of the first embodiment, it is preferable to perform the dot shift correction process. In order to detect the dot misalignment, the vibrating unit 101 and the photodetector 110 of this embodiment are the same as those of the first embodiment as components, but are attached at different angles.

FIG. 29 is a cross-sectional view of the vibrating portion 101 of the second embodiment taken along a cross section (xy plane) parallel to the longitudinal direction of the light guide path 102.

Compared with the case of the first embodiment, the vibrating section 101 of the second embodiment is arranged at an angle of 45°. As a result, the displacement of the emission end 102a of the light guide path 102 draws the locus shown in FIG.

Further, FIG. 30 is a diagram showing the structure and installation direction of the photodetector 110. As can be seen from comparison with FIG. 4 of the first embodiment, the photodetector 110 of the second embodiment is arranged at an angle of 45°. In the second embodiment, the drive axis of the vibrating section 101 in the optical scanning section 16 and the division axis of the photodetector 110 correspond to each other. Specifically, a part of the light before the lateral expansion by the lens is branched by the prism 109 and detected by the photodetector 110.

With such a configuration, even in the case of an optical scanning device that projects a rectangular projection image, it is possible to detect dot misregistration as in the first embodiment. That is, the same effect as that of the first embodiment can be realized.

Next, a configuration suitable for mounting the configuration of Example 2 on a head mounted display (Head Mounted Display: HMD) will be described. As is clear from FIG. 2, the structure of the optical scanning unit 10 becomes large in the direction in which a part of the light is deflected by the prism 109. On the other hand, in a head-mounted display, it is preferable that the thickness of the head mounted display in the horizontal direction is small when the head-mounted display is mounted on a head that is oriented in the horizontal direction.

Therefore, as shown in FIG. 24, the direction in which a part of the light is deflected by the prism 109 is preferably a substantially vertical direction when the head mounted display 70 is mounted on the head. This can reduce the load felt by the wearer when the head mounted display 70 is worn. Further, regarding the photodetector that receives light at the deflected destination, it is preferable to arrange the photodetector so that the division axis corresponds to the drive axis.

As described above, according to the second embodiment, it is possible to properly display an image in the optical scanning device having a function of displaying an image.

Next, the configuration of the optical scanning device of the third embodiment will be described.
As described with reference to FIG. 13, the optical scanning device 1 is a cantilever secondary resonance system including the light guide path 102. In the above embodiments, it was not assumed that the resonance frequency of the light guide path 102 changes from f0 to f1 due to factors such as temperature. The third embodiment can properly display an image even when such a resonance frequency changes.

The configuration of the optical scanning device of the third embodiment is the same as that of the second embodiment, and is different in that a phase difference measuring unit 23 that receives a differential signal is used.

The role of the phase difference measuring unit 23 in the third embodiment will be described. The phase difference measuring unit 23 measures the phase difference between the first sine wave S1 and the first differential signal D1 and outputs it as a phase difference measurement value Δθ1. Further, the phase difference measuring unit 23 measures the phase difference between the second sine wave S2 and the second differential signal D2 and outputs it as the phase difference measurement value Δθ2.

The first sine wave S1 is a resonance frequency component of the x-axis drive signal, and the fact that the first sine wave S1 becomes zero means that the drive signal value in the x-axis direction is zero. Further, the first differential signal D1 becoming zero means the timing when the center of the light spot passes through the dividing line of the photodetector 110 on the x axis.

As described in FIG. 13, if the phase of the secondary resonance system can be measured, the frequency of the current amplification drive signal with respect to the resonance frequency depends on whether or not the value of the measured phase is larger than −90°. Can be determined to be large or small. By utilizing this, it is possible to change the frequency of the amplified drive signal Vdx1 from f0 to f1.

The phase difference measuring unit 23 in the third embodiment determines the position of the transfer function from the first sine wave S1 which is the frequency component of the amplified drive signal Vdx1 to the displacement of the light spot detected by the differential signal D1 in the x-axis direction. Detect the phase difference. The phase difference of −90° is the phase of displacement of the light guide path 102 in the x-axis direction with reference to the amplified drive signal Vdx1. The phase difference measured by the phase difference measuring unit 23 is a value obtained by adding the delay d1 due to the electric circuit of the amplifying unit and the delay d2 due to the electric circuit of the differential signal generating unit 32, in addition to the above-mentioned phase difference. That is, the phase difference measured by the phase difference measuring unit 23 in the resonance state is not −90°. In this specification, for the sake of explanation, the value Δθplus obtained by converting the sum of d1 and d2 into the phase of the driving frequency is set to 10°. At this time, the phase difference measured by the phase difference measuring unit 23 in the resonance state is −100°.

The configuration of the phase difference measuring unit 23 will be described with reference to FIG.
The binarization circuit 2301 binarizes and outputs the first sine wave S1. The delay device 2302 delays the output signal of the binarization circuit 2301 for a predetermined time. The OR circuit 2303 outputs a signal obtained by ORing the output signal of the binarization circuit 2301 and the output signal of the delay device 2302.

The binarization circuit 2304 binarizes and outputs the first differential signal D1. The delay device 2305 delays the output signal of the binarization circuit 2304 by a predetermined time. The OR circuit 2306 outputs a signal obtained by ORing the output signal of the binarization circuit 2304 and the output signal of the delay device 2305.

The counter circuit 2307 has an rst terminal and a stop terminal as input terminals, starts counting in synchronization with the input to the rst terminal, ends counting in synchronization with the input to the stop terminal, and simultaneously ends. Outputs the count value of the hour. Thereby, the time difference from the input to the rst terminal to the input to the stop terminal is measured. The output signal of the logical sum circuit 2303 is connected to the rst terminal and the output signal of the logical sum circuit 2306 is connected to the stop terminal, and the time difference is measured. This time difference can be converted into phase difference information when combined with the resonance period information of the waveguide 102. In this specification, the output signal of the counter circuit 2307 is referred to as the phase difference measurement value Δθ1. With the above configuration, the phase difference measuring unit 23 measures the phase difference between the first sine wave S1 and the first differential signal D1 and outputs it as the phase difference measurement value Δθ1.

Further, the phase difference measuring unit 23 measures another phase difference between the second sine wave S2 and the second differential signal D2, and outputs another phase difference measurement value Δθ2, another set of similar circuits, Contains. The similar circuits are the binarization circuit 2308, the delay unit 2309, the OR circuit 2310, the binarization circuit 2311, the delay unit 2312, the OR circuit 2313, and the counter circuit 2314 in FIG. The output signal of the counter circuit 2314 is referred to as the phase difference measurement value Δθ2.

Further, the phase difference measuring unit 23 has a counter circuit 2315. The counter circuit 2315 measures the phase difference between the first differential signal D1 and the second differential signal D2, and outputs it as the phase difference measurement value Δθxz. This measurement is performed with a configuration in which the output signal of the logical sum circuit 2306 is connected to the rst terminal of the counter circuit 2315 and the output signal of the logical sum circuit 2313 is connected to the stop terminal.

Further, as can be seen from FIG. 15, four circuit configurations (portions indicated by 231, 232, 233, and 234 in FIG. 14) including a binarization circuit 2301, a delay unit 2302, and an OR circuit 2303 are included. There is. In this specification, this circuit will be referred to as a zero-cross detection circuit, and in the following embodiments, the name of the zero-cross detection circuit will be described.

Waveforms inside the phase difference measuring unit 23 in the third embodiment will be described with reference to FIG. 16A shows the first sine wave S1, and FIG. 16B shows the output of the zero-cross detection circuit 231. 16C and 16D show signals in the state 0, that is, in the resonance state, FIG. 16C shows the first differential signal D1, and FIG. 16D shows the output of the zero-cross detection circuit 232. 16(e) and 16(f) are signals when the state 1 is out of the resonance state, in which (e) is the first differential signal D1 and (f) is the output of the zero-cross detection circuit 232. is there.

As can be seen from FIG. 16, the output of the zero cross detection circuit 231 becomes High at the zero cross timing of the first sine wave S1. In this way, the zero-cross detection circuit 201 can output a signal that becomes High for the delay time in the delay unit 2302 at the timing when the input signal zero-crosses. That is, the zero cross of the input signal can be detected.

Similarly, the output of the zero-cross detection circuit 232 becomes High at the zero-cross timing of the first differential signal D1. As a result, the phase difference measured by the counter circuit 2307 in the resonance state 0 is Δθtgt in FIG. 16.

Here, Δθtgt is a value corresponding to about 90° when converted to the phase of the driving frequency, but becomes a large value by the above-mentioned delay Δθplus. In the present embodiment, as described above, Δθtgt is 100 degrees when converted into the phase of the driving frequency. Here, Δθtgt can be restated as the phase difference measured in the resonance state.

In the case of the state 1 out of the resonance state, the phase difference measured by the counter circuit 2307 becomes Δθ1 shown in FIG. Using the values shown in FIG. 13, Δθ1 is the sum of the absolute value of Δθ′ and Δθplus.

In this way, the phase difference can be measured by detecting the zero-cross timing of the first sine wave S1 and the zero-cross timing of the first differential signal D1 and measuring the time difference between them. However, the configuration of the phase difference measuring unit 23 of the third embodiment is an example for measuring the phase difference, and various forms other than this are conceivable.

For example, the x-axis driving sine wave Sx may be used instead of the first sine wave S1. Furthermore, the phase difference measuring unit 23 has a configuration in which only the phase information of the first sine wave S1 is input from the drive signal generating unit 20, and the first sine wave S1 at the zero cross timing of the first differential signal D1 is detected. The phase value may be output as the phase difference measurement value Δθ1.

In the state where the phase difference measurement value measured by the phase difference measuring unit 23 matches the phase difference Δθtgt measured in the resonance state, the first sine wave S1 at the zero cross timing of the first differential signal D1 The phase value becomes Δθtgt. That is, when the drive frequency matches the resonance frequency, the phase value of the first sine wave S1 at the zero-cross timing of the first differential signal D1 becomes Δθtgt.

FIG. 17 shows a flowchart of the controller 40 in the optical scanning device 1 according to the third embodiment.

When the optical scanning device 1 starts its operation (step S1001), the controller 40 reads out the information necessary for the processing of each part constituting the optical scanning device 1 from the storage unit 41 (step S1002). In this, information regarding the functions f(r), a(r), and b(r), the magnification in the first variable gain 2005, the magnification in the second variable gain 2006, and the second sine wave generation unit 2003. Phase difference and the like are included.

Subsequently, the controller 40 determines whether or not there is a display start instruction from the external control device 50 through the input/output control circuit 42 (step S1003). If there is no display start instruction (No in step S1003), the process returns to step S1003.

When there is a display start instruction (Yes in step S1003), the controller 40 issues an instruction to the drive signal generation unit 20 and starts output of the drive signal (step S1004). In the present embodiment, output is started by setting a value other than zero as the magnification in the first variable gain 2005 and the magnification in the second variable gain 2006. At this time, the set value is the set value read from the storage unit 41 in step S1002.

Subsequently, the controller 40 gives an instruction to the remapping control unit 21 to give an instruction to start the remapping control (step S1005). The controller 40 transmits information regarding the function used in the calculation in the remapping control unit 21, and the remapping control is started. Further, the mechanism for reading out the gradation data of the pixel corresponding to the coordinates (x _calc , y _calc ) in the video information stored in the display image storage memory 33 is implemented by hardware, and the pixel data of the pixel is read in step S1005. Readout of gradation data is also started.

Then, the controller 40 gives an instruction to the emission control unit 22 to give an instruction to start emission control of the laser (step S1006). As described above, the image is displayed.

The process of storing the video signal input from the external control device 50 through the input/output control circuit 42 in the display image storage memory 33 is implemented by hardware, and the storage of the video signal in the display image storage memory 33 is not performed. Immediately after the trajectory of the optical scanning device 1, it is assumed that the scanning is always performed.

Subsequently, the controller 40 acquires the phase difference measurement values Δθ1 and Δθ2 from the phase difference measuring unit 23 in synchronization with the switching of the display frame (step S1007).

After step S1007, the controller 40 determines whether the number of acquisition times has reached N (step S1008). If the number of acquisitions is not N (No in step S1008), the process returns to step S1007 to acquire the phase difference measurement value in the next frame.

When the number of acquisitions is N (Yes in step S1008), the average value of the acquired phase difference measurement values is calculated (step S1009). Let Δθavg be the average value of the calculated phase difference measurement values. Further, the count of the number of acquisitions is reset at this timing. By the above operation, the average value of the phase difference measurement values is calculated every N frames. In this embodiment, the average value of N Δθ1 and N Δθ2 is Δθavg.

After step S1009, the controller 40 determines whether the absolute value of the difference between the calculated average values Δθavg and Δθtgt of the phase difference measurement values is less than a predetermined threshold Δθth (step S1010). Here, Δθtgt is a phase difference to be measured in the resonance state.

If the absolute value of the difference between the calculated average value Δθavg of the phase difference measurement value and Δθtgt is not less than the predetermined threshold value Δθth (No in step S1010), it is determined that the resonance state is not satisfied, and the driving is performed. The signal generator 20 is instructed to change the drive frequency fdrv (step S1011). At this time, an instruction is given by estimating how much the drive frequency should be changed according to the value of the difference between the calculated average values Δθavg and Δθtgt of the phase difference measurement values. After step S1011, the process returns to step S1007. As a result, after the drive frequency is changed, the phase difference measurement and the determination as to whether or not there is a resonance state (processing from step S1007 to step S1010) are performed again.

When the absolute value of the difference between the calculated average values Δθavg and Δθtgt of the phase difference measurement values is less than the predetermined threshold value Δθth (Yes in step S1010), it is determined that the resonance state is present. The following is the flow when the optical scanning device 1 ends the operation.

The controller 40 determines whether there is a display end instruction from the external control device 50 through the input/output control circuit 42 (step S1012). If there is no display start instruction (No in step S1012), the process returns to step S1007.

When the display start instruction is given (Yes in step S1012), the controller 40 gives an instruction to the light emission control unit 22 to give an instruction to end the laser light emission control (step S1013). After step S1013, the end of operation of each unit is instructed (step S1014), and the operation ends (step S1015). Here, the respective units are, for example, the drive signal generation unit 20 and the remapping control unit 21.

Next, the effect of the third embodiment will be described. The first effect of the third embodiment is that the resonance state of the light guide path 102 can be maintained and appropriate image display can be continued without interrupting the image display.

In the third embodiment, the photodetector 110 detects a part of the light while displaying an image, and changes the drive frequency so as to maintain the resonance state according to the detection result. When the resonance state cannot be maintained, the displacement of the light guide path 102 may be significantly reduced as shown in FIG. As a result, the size of the image display screen of the optical scanning device 1 becomes small. According to the third embodiment, even if the resonance state changes due to factors such as temperature, it is possible to detect whether or not the resonance state is present, and the drive frequency can be made to follow the resonance frequency. Can be maintained.

Further, in the third embodiment, it is not necessary to interrupt the image display because it is detected whether or not the light is in the resonance state by using a part of the light during the image display. Further, since information on whether the resonance frequency is higher or lower than the drive frequency can be detected, the drive frequency can follow the resonance frequency at high speed.

The second effect of the third embodiment is that the detection of whether or not the resonance state is achieved is realized by the phase difference measurement using the differential signal. The first point in realizing this is the generation of the differential signal of this embodiment. The present inventors devised the differential signal of Example 3 by utilizing the fact that the light spot reaching the photodetector 110 has an area. According to the third embodiment, it is possible to detect the timing when the center of the light spot is located on the division line of the 4-division detector.

The second point of interest is that the drive axis of the vibrating section 101 in the optical scanning section 10 and the division axis of the photodetector 110 correspond to each other. Here, the drive axes of the vibrating portion 101 are the x-axis and the y-axis, and the light traveling to the photodetector 110 is deflected at a right angle by the prism 109, so the corresponding coordinate axes are the x-axis and the z-axis. In the present specification, "the drive axis corresponds to the split axis" means that the split axis matches the x axis and the z axis.

The differential signal of the third embodiment is zero-crossed when the center of the light spot is located on the dividing line of the 4-division detector, and the timing can be detected. In the third embodiment, since the phase characteristic of the transfer function from the amplified drive signal to the displacement of the light guide path 102 is used, it is necessary to detect the timing of the drive signal corresponding to the zero crossing of the differential signal. Therefore, it is preferable that the drive axis of the vibration unit 101 and the split axis of the photodetector 110 correspond to each other. With this configuration, the x-axis drive (only) contributes to the zero crossing of the first differential signal D1. Similarly, it is the y-axis drive (only) that contributes to the zero crossing of the second differential signal D2.

Therefore, the timing of the drive signal corresponding to the zero-cross of the differential signal is the zero-cross point of the drive signal of the axis that contributes. Therefore, only the drive signal of a single axis can be used to detect the timing of the drive signal corresponding to the zero crossing of the differential signal. As a result, it becomes possible to detect whether or not it is in a resonance state. When the drive axis and the split axis do not correspond to each other, accurate detection cannot be performed, for example, when there is a difference in sensitivity between the x-axis and y-axis vibrating section 101.

If the drive axes of the vibrating section 101 are not orthogonal, at least one of the drive axes may correspond to either the x axis or the z axis that is the split axis. Even in this case, the phase difference measurement is possible.

The third effect of the third embodiment is that it is possible to accurately detect whether or not there is a resonance state with a small and inexpensive structure by the structure that takes a differential signal by the four-division detector. Compared with the configuration that uses a device PSD (Position Sensing Device) that detects a position, the configuration of the third embodiment is a compact and inexpensive configuration. This embodiment is because it is not necessary to provide a lens between the prism 109 and the photodetector 110, and an inexpensive 4-division detector is used.

The fourth effect of the third embodiment is that since the differential signal is normalized by the total light amount, it is not affected by the brightness of the gradation data (R, G, B) and accurate phase difference detection is possible. It is a point. In other words, the phase difference can be detected even when displaying an image close to black. The problem that the emission brightness of the laser changes depending on the brightness of the gradation data (R, G, B) and is not constant is a problem peculiar to a device that displays an image.

Furthermore, the fifth effect of the third embodiment is that the distortion of the projected image after the drive frequency is changed to follow the resonance frequency is favorably corrected. According to the configuration of the third embodiment, calculation of coordinates including the corrections of (Equation 5) to (Equation 7) is performed using the changed drive frequency. Here, consider a case where the resonance state changes from the first resonance state due to temperature or the like, the drive frequency is changed to follow the resonance frequency, and the state shifts to the second resonance state. The present inventors have found that the change in distortion of the projected image is small between the first resonance state and the second resonance state. That is, the distortion correction functions f(r), a(r), and b(r) determined at the time of shipment can be used even after the drive frequency is changed to follow the resonance frequency. Therefore, the distortion of the projected image can be favorably corrected by performing the image coordinates in the remapping control unit using the changed drive frequency.

The sixth effect of the third embodiment is that since frame averaging is performed in phase difference measurement, time resolution is improved and accurate phase difference measurement is possible. Note that this utilizes that the time of one frame is sufficiently small with respect to the time constant at which the resonance frequency changes.

The seventh effect of the third embodiment is that it is compatible with the brightness correction. Although the differential signal of the third embodiment is normalized, the higher the emission brightness, the more advantageous the S/N is, and the more accurate measurement becomes possible. When lowering the luminance, the light emission control unit 22 of the third embodiment lowers the luminance by lowering the frequency of turning on the laser instead of uniformly lowering the emission intensity of the laser. As a result, even in the projection area where the brightness is reduced, the emission brightness does not decrease, so that it is compatible with the brightness correction.

In the third embodiment, the phase difference Δθtgt to be measured by the phase difference measuring unit 23 in the resonance state is described without distinguishing between the x-axis and the y-axis, but even if the x-axis and the y-axis have different values. I do not care. This is because, for example, the characteristics of the amplification section 30 are not exactly the same. For example, adjustment is made so that the phase difference Δθ1 between the first sine wave S1 and the first differential signal D1 with respect to the x-axis becomes 110°, and the second sine wave S2 and the second differential wave with respect to the y-axis are obtained. The phase difference Δθ2 with the signal D2 may be adjusted to 112°.

Further, in the third embodiment, both the phase difference Δθ1 between the first sine wave S1 and the first differential signal D1 and the phase difference Δθ2 between the second sine wave S2 and the second differential signal D2. Although the phase difference is measured by using, it is possible to use either one. For example, only the phase difference Δθ1 between the first sine wave S1 and the first differential signal D1 may be used. In this case, the photodetector 110 may be a two-divided detector instead of the four-divided detector. For example, in FIG. 4, the two-divided detector in which the regions 110A and 110B are a single light receiving surface and the regions 110C and 110D are a single light receiving surface may be used.

Furthermore, in the third embodiment, the configuration in which the phase difference measuring unit 23 performs the measurement four times per revolution of the locus has been described, but the measurement may be performed only at one point on the light scanning locus. In other words, the phase difference measurement is possible even if the measurement is performed once per frame.

Further, the vibrating section 110 of the third embodiment has been described as having the two drive shafts of the x-axis and the y-axis, but the third embodiment is similarly applicable to the case where the vibrating section has one drive shaft. is there. The image display in this case is, for example, when the screen coated with the photosensitive agent moves in the direction orthogonal to the drive axis of the vibrating unit and the laser is turned on in a time division manner by the optical scanning device, an image is displayed on the screen. can do. In this specification, such a form is also referred to as image display.

Furthermore, although the gain setting of the photodetector 110 is not mentioned in the third embodiment, the gain setting of the photodetector 110 may be switched according to the brightness of the pixel to be displayed. Specifically, the gain setting of the photodetector 110 is switched according to the gradation data (R, G, B) output from the display image storage memory 33. This reduces the influence of the brightness of the pixels to be displayed and enables more accurate phase difference measurement.

As described above, according to the third embodiment, it is possible to properly display an image in the optical scanning device having a function of displaying an image.

Next, the configuration of the optical scanning device of the fourth embodiment will be described.
The optical scanning device according to the first exemplary embodiment has a configuration that detects whether or not a resonance state is present and maintains the resonance state. In addition to this, the fourth embodiment is an embodiment in which a more appropriate image display is realized by estimating the optical scanning trajectory.

FIG. 18 is a block diagram showing the optical scanning device 2 including the optical scanning unit 10. The same components as those in FIG. 1, which is the block diagram of the first embodiment, are designated by the same reference numerals, and the description thereof will be omitted. The difference from the first embodiment in the configuration is the moving time measuring unit 24, and the connection state of a part of the blocks and the content of the command from the controller 40 are different. The moving time measuring unit 24 estimates the moving time of the optical scanning locus, in other words, the moving speed, based on the differential signal output from the differential signal generating unit 32.

The controller 40 estimates the trajectory of the optical scanning based on the information on the moving time measured by the moving time measuring unit 24 and the phase difference measured by the phase difference measuring unit 23. Further, the controller 40 gives an instruction to change the distortion correction function of the remapping control unit 21 as needed.

The configuration of the traveling time measuring unit 24 according to the fourth embodiment will be described with reference to FIG. The subtractor 2401 outputs a value obtained by subtracting the value Th1d1 designated by the controller 40 from the first differential signal D1. Further, the subtractor 2403 outputs a value obtained by subtracting the value Th2d1 instructed by the controller 40 from the first differential signal D1. In the fourth embodiment, the value Th1d1 is a positive value, the value Th2d1 is a negative value, and the values Th1d1 and Th2d1 are the same absolute value.

The zero-cross detection circuit 2402 receives the output signal of the subtractor 2401 as an input and generates a signal that is high for a predetermined time at the zero-cross timing. Further, the zero-cross detection circuit 2404 receives the output signal of the subtractor 2403 as an input and generates a signal that becomes High for a predetermined time at the timing of zero-cross.

The counter circuit 2305 has an rst terminal and a stop terminal as input terminals, starts counting in synchronization with the input to the rst terminal, and ends counting in synchronization with the input to the stop terminal, and simultaneously ends. Outputs the count value of the hour. The output signal of the zero-cross detection circuit 2402 is connected to the rst terminal and the output signal of the zero-cross detection circuit 2404 is connected to the stop terminal, and the time difference ΔTx is measured.

The subtractor 2406 outputs a value obtained by subtracting the value Th1d2 instructed by the controller 40 from the second differential signal D2. Further, the subtractor 2408 outputs a value obtained by subtracting the value Th2d2 instructed by the controller 40 from the second differential signal D2. In the fourth embodiment, the value Th1d2 is a negative value, the value Th2d2 is a positive value, and the values Th1d2 and Th2d2 are the same absolute value.

The zero-cross detection circuit 2407 receives the output signal of the subtractor 2406 as an input, and generates a signal that becomes High for a predetermined time at the zero-cross timing. Further, the zero-cross detection circuit 2409 receives the output signal of the subtractor 2408 as an input and generates a signal that becomes High for a predetermined time at the timing of zero-cross.

The counter circuit 2310 has an rst terminal and a stop terminal as input terminals, starts counting in synchronization with the input to the rst terminal, ends counting in synchronization with the input to the stop terminal, and simultaneously ends. Outputs the count value of the hour. The output signal of the zero-cross detection circuit 2407 is connected to the rst terminal and the output signal of the zero-cross detection circuit 2409 is connected to the stop terminal, and the time difference ΔTz is measured.

With the above configuration, the time ΔTx from when the first differential signal D1 has the value Th1d1 to when it has the value Th2d1 is measured. Further, the time ΔTz from when the second differential signal D2 has the value Th1d2 to when it has the value Th2d2 is measured.

Next, the role of the travel time measuring unit 24 in the fourth embodiment will be described. Here, for the sake of explanation, the value Th1d1 and the value Th1d2 are assumed to be 0.2.

The meaning that the value of the differential signal D1 becomes 0.2 will be described with reference to FIG. The differential signal D1 being −0.2 means that the light spot detected by the photodetector 110 is divided by the division axis in the z-axis direction of the photodetector 110 at an area ratio of 6:4. means. That is, as shown in FIG. 20A, the center of the light spot under the condition that the differential signal D1 becomes 0.2 rides on the line segment L1 parallel to the z-axis, and the value of the x-axis becomes the same. ..

Next, the meaning of the travel time measured by the travel time measuring unit 24 according to the fourth embodiment will be described with reference to FIG. SP101 and SP102 indicate the size of the light spot. For the sake of explanation, it is assumed that the optical scanning locus from SP101 to SP102 is a circle centered on the origin. SP101 is a light spot when the value of the differential signal D1 is 0.2, and SP102 is a light spot when the value of the differential signal D1 is -0.2. The moving time measured by the moving time measuring unit 24 is the time required for the light spot to move from the position of SP101 to the position of SP102. That is, the measured travel time includes information on the central angle of the sector shown by Sector 100 in FIG. This is because the frequency fdrv of the drive signal is known.

Here, when the radius of the optical scanning locus from SP101 to SP102 is 100, consider the case of a locus of radius 50. The moving time measured at this time becomes information on the central angle of the sector shown by Sector 50 in FIG. A line segment parallel to the z-axis on which the center of the light spot rides when the differential signal D1 becomes 0.2 is L1, and a z-axis on which the center of the light spot rides when the differential signal D1 becomes -0.2. The line segment parallel to is L2. The moving time measured by the moving time measuring unit 24 of the fourth embodiment is the moving time from when the center of the light spot passes L1 to when it passes L2. Here, for the sake of explanation, the threshold value is described as a large value of 0.2, but the threshold value may be a smaller value. This moving time means the moving time in the vicinity of the light spot passing through the z axis.

In other words, the information on the moving time measured by the moving time measuring unit 24 of the fourth embodiment can be converted into the moving speed in the vicinity of the light spot passing the z axis. Further, since the frequency fdrv of the drive signal is known, it is possible to convert it to the phase difference from the center of the light spot passing L1 to passing L2.

FIG. 21 shows the values of the differential signal D1 (see FIG. 21A) and the differential signal D2 (see FIG. 21B) when the radius of the circular locus is changed. This is a differential signal when the radius is changed to 0.75, 0.5, and 0.25, where 1 is the maximum radius at which the light spot can be detected by the photodetector. It can be seen that the moving time from when the differential signal D1 changes from 0.2 to −0.2 is shorter when the radius is larger. This is because the larger the radius is, the faster the moving speed is in the vicinity of passing through the z axis. As described above, the moving time measured by the moving time measuring unit 24 of the embodiment means the moving time in the vicinity of the light spot passing through the z axis. It should be noted that although the optical scanning locus is circular for the sake of explanation, it is clear that the same explanation is applicable even if the optical scanning locus is elliptical.

In the fourth embodiment, the controller 40 scans the light based on the phase difference measurement value Δθxz measured by the phase difference measuring unit 23 and the moving times ΔTx and ΔTz measured by the moving time measuring unit 24. Estimate the shape of. The present inventors have found that the shape of the scanning locus of light can be estimated from three pieces of information of the phase difference measurement value Δθxz and the movement times ΔTx and ΔTz.

Here, the reason why the trajectory can be estimated from these three values will be described. The phase difference measurement value Δθxz is the phase difference from when the light spot passes the x axis to when it passes the z axis. When the light scanning locus is a circle, Δθxz is 90°. Here, consider the case where the locus becomes an ellipse that expands and contracts in the x-axis or z-axis direction as shown in FIG. Also in this case, Δθxz becomes 90°. Therefore, the trajectory cannot be estimated only by the information of Δθxz.

Next, the moving time ΔTx was the moving time near the light spot passing the x axis, and the moving time ΔTz was the moving time near the light spot passing the z axis. When the light scanning locus is a circle, ΔTx and ΔTz have the same value. Here, consider a case where the locus is an ellipse and the major axis of the ellipse is inclined by 45° in the xz plane as shown in FIG. When the major axis of the ellipse is inclined by 45° in the xz plane, ΔTx and ΔTz have the same value. Furthermore, depending on the lengths of the major and minor axes of the ellipse, there are conditions under which the values of ΔTx and ΔTz in the case of a circle are the same. That is, the trajectory cannot be estimated only by the information on the movement times ΔTx and ΔTz.

However, the shape of the scanning locus of light can be estimated by using the three pieces of information of the phase difference measurement value Δθxz and the movement times ΔTx and ΔTz. First, for simplicity, consider determining that the trajectory is a circle. When the locus is a circle, the phase difference measurement value Δθxz becomes 90°. At this time, the locus becomes an ellipse with the x-axis and the z-axis as the major axis and the minor axis. Further, when the locus is a circle, ΔTx and ΔTz have the same value. At this time, the locus becomes an ellipse whose major axis and minor axis are the axes inclined by 45° in the xz plane. That is, both are limited to a circle centered on the origin of the xz plane. Further, since the speed when passing the x-axis can be calculated from the information of ΔTx and the information of the driving frequency of the known driving signal, the radius of the circle can also be calculated.

Next, let us consider estimating an arbitrary elliptical shape. When the length of the long axis of the ellipse is 2a, the length of the long axis is 2b, and the inclination of the long axis is θ, it is considered to estimate an elliptical shape determined from arbitrary a, b, and θ. As an example, consider an ellipse with a=1, b=0.6, and θ=30°. This ellipse has a shape as shown in FIG.

At this time, the phase difference measurement value Δθxz is uniquely determined if the shape of the ellipse is determined. Also, the moving times ΔTx and ΔTz are uniquely determined if the shape of the ellipse and the threshold value are determined, that is, the shape of the locus of the ellipse and the combination of the three variables (θxz, ΔTx, ΔTz) are unique. Decided.

That is, the shape of the optical scanning locus can be calculated from the three variables (θxz, ΔTx, ΔTz). When calculating the shape of the trajectory, the controller 40 may store the correspondence between the three variables and the shape, or the controller 40 may have an algorithm for estimating the shape of the trajectory.

FIG. 23 shows a flowchart of the controller 40 in the optical scanning device 1 of the fourth embodiment. The same steps as those in FIG. 16, which is the flowchart of the first embodiment, are designated by the same reference numerals, and the description thereof will be omitted.

The difference from FIG. 16 which is the flowchart of the first embodiment is step S1016 instead of step S1007, and the subsequent processing in the case of Yes in step S1010 is different. Here, the different steps will be described.

In step S1016, the controller 40 acquires the phase difference measurement values Δθ1, Δθ2, and Δθxz from the phase difference measuring unit 23 in synchronization with the switching of the display frame. Further, the moving times ΔTx and ΔTz are acquired from the moving time measuring unit 24 (step S1016). After step S1016, the controller 40 determines whether or not the number of acquisition times has reached N (step S1008).

If the absolute value of the difference between the calculated average value Δθavg of the phase difference measurement value and Δθtgt is less than the predetermined threshold value Δθth (Yes in step S1010), it is determined that the resonance state exists. In this embodiment, after it is determined that the optical scanning locus is in the resonance state, the optical scanning locus is continuously estimated.

If Yes in step S1010, the controller 40 estimates the shape of the optical scanning locus from the three variables (θxz, ΔTx, ΔTz) (step S1017). At this time, since three variables (θxz, ΔTx, ΔTz) are also measured N times, the optical scanning locus may be estimated after calculating the average value of each.

Subsequently, the controller 40 determines whether or not there is a deviation in the optical scanning locus (step S1018). If there is a deviation in the optical scanning locus (Yes in step S1018), the controller 40 instructs the remapping control unit 21 to change the distortion correction function (step S1019).

If there is no deviation in the optical scanning locus (No in step S1018), the process advances to step S1012. The subsequent flow is the flow when the optical scanning device 1 finishes its operation, and is the same as the case of the first embodiment.

Next, the effect of the fourth embodiment will be described. Since the fourth embodiment includes the functions of the first embodiment, the effects obtained by the first embodiment can be obtained by the fourth embodiment. Here, other effects specific to the fourth embodiment will be described.

In the fourth embodiment, the scanning state of the light is estimated while maintaining the resonance state, and the distortion correction function is changed as necessary. The effect of the fourth embodiment is that the distortion of the projected image can be satisfactorily corrected. The present inventors have found that when the resonance frequency changes significantly due to factors such as temperature and aging, the distortion of the projected image can change even if the drive frequency is changed accordingly. The reason for this is a combination of several factors. To give an example, when the resonance frequency changes due to a change in mechanical characteristics such as the rigidity of the light guide path 102 due to temperature, the frequency of the amplification section 40 changes. The characteristics do not change. Therefore, even in the same resonance state, the transfer functions from the drive signal to the displacement of the light spot are not the same. As a result, in the first embodiment, distortion of the projected image may occur especially when the change in the resonance frequency is large.

On the other hand, in the fourth embodiment, the phase difference measurement value Δθxz and the moving times ΔTx and ΔTz are measured using the two differential signals D1 and D2. Then, the trajectory of the optical scanning is estimated from these three measurement results. Estimating the trajectory of optical scanning is nothing but estimating the distortion of the projected image. In the fourth embodiment, the distortion of the projected image is corrected by changing the distortion correction function. By performing the correction with the distortion correction function without changing the drive parameter, there is an advantage that the correction of the distortion of the projected image can be instantly reflected.

In the fourth embodiment, the distortion of the projected image is corrected by the distortion correction function, but the distortion may be corrected by the drive parameter of the drive signal. For example, the magnification in the first variable gain 2005, the magnification in the second variable gain 2006, and the phase difference _{Δθ drv} of the second sine wave may be changed.

Next, a first modified example of the fourth embodiment will be described. The first modification of the fourth embodiment is an embodiment for coping with the case where the photodetector 110 is displaced. When the structure of the optical scanning unit 10 is miniaturized, the positional deviation of the photodetector 110 may occur.

FIG. 25 shows a light spot detected by the photodetector 110 during the optical scanning. SP3 indicates the size of the light spot, and SP3-0 indicates the center of the light spot. Further, O'indicates the center of the locus. When the positional deviation occurs, as can be seen from FIG. 25, a part of the light spot goes out of the light receiving surface of the photodetector 110.

One configuration for avoiding this is a configuration in which the prism 109 and the photodetector 110 are made large so that the photodetector 110 can receive a light spot even if there is a positional deviation. However, in this case, there is a disadvantage that the optical scanning unit 10 becomes large. Moreover, since the optical path length to the photodetector 110 is extended, the size of the light spot on the photodetector 110 is reduced. Since the differential signals employed in the first and second embodiments utilize the fact that the light spot has an area, it is preferable that the size of the light spot is large.

Therefore, in the present modification, even if the photodetector 110 has a positional shift, the positional shift is dealt with by changing the instruction content from the controller 40 with the same configuration as in the second embodiment.

For the sake of explanation, consider the simple differential signals E1 and E2 defined by the following (Equation 14) and (Equation 15).

FIG. 26 is a diagram showing a simple differential signal and a differential signal when the phase of optical scanning is changed when the photodetector 110 is displaced in the configuration of the fourth embodiment (FIG. 4 and FIG. Similarly, the optical scanning locus is assumed to be a circle centered on the origin). Each series in the graph is a signal value when the radius of the trajectory is changed. 26(a-1) is a first simple differential signal E1, (a-2) is a second simple differential signal E2, (b-1) is a first differential signal D1, (b-2). ) Is the second differential signal D2. For comparison (c-1) and (c-2), the prism 109 and the photodetector 110 are made large for comparison so that the photodetector 110 can receive a light spot even if there is a positional deviation. The differential signal of is shown.

In describing FIG. 26, the first simple differential signal E1 and the first differential signal D1 will be described as an example. When the photodetector 110 is not displaced, the first differential signal D1 is zero-crossed when the optical scanning phases are 0° and 180°. On the other hand, when the photodetector 110 has a positional deviation, as can be seen from FIG. 26, in the case of a simple differential signal, the optical scanning phase has different values between 0° and 180°, but normalization is performed. The differential signals D1 and D2 that are present have the same value when the optical scanning phase is 0° and 180°. Then, as can be seen by comparing (b-1) and (c-1), by performing the normalization, a part of the light spot goes out of the light receiving surface of the photodetector 110 due to the positional deviation. Even if it does, the effect can be corrected. As a result, it is possible to measure the phase difference and the moving time. The details of the measurement in this modification will be described below.

When the photodetector 110 is misaligned, the value of the differential signal D1 is not zero when the optical scanning phases are 0° and 180°, as can be seen from FIG. 26(b-1). This is because the light spot is not bisected by the split axis when the optical scanning phases are 0° and 180°. However, if the direction and magnitude of the positional deviation are known, the value of the differential signal D1 when the optical scanning phase is 0° and 180° can be determined.

That is, when the photodetector 110 is displaced when the optical scanning unit 10 is assembled, the controller 40 stores the value D1-0 of the differential signal D1 when the optical scanning phases are 0° and 180° during assembly. I'll do it. Similarly, the value D2-0 of the differential signal D2 when the optical scanning phases are 90° and 270° is similarly stored in the controller 40 during assembly. Further, the differential signal generation unit 32 of the present modified example performs the following operations of (Expression 16) and (Expression 17) on these four signals to obtain the first differential signal D1′ and the second differential signal. D2' is output.

With the above configuration, it is possible to measure the phase difference and the moving time, as in the case of the second embodiment. The effect of this modification is that the phase difference and the movement time can be measured even if the photodetector 110 is displaced during the assembly of the optical scanning unit 10, and a good image can be displayed. It is a point. In particular, by normalizing the differential signal when it is generated, it is possible to deal with a case where a part of the light spot goes out of the light receiving surface of the photodetector 110. As a result, it is not necessary to enlarge the prism 109 and the photodetector 110, and the optical scanning unit 10 can be downsized.

Compared with the configuration using the device PSD that detects the position instead of the photodetector 110 that is the four-division detector, the present embodiment has the effect from the viewpoint described above. Since the PSD is a device that outputs the center of gravity of the received light, the position cannot be detected when a part of the light spot goes out of the light receiving surface of the PSD.

Therefore, in the case of using the PSD, it is necessary to receive the entire light spot on the PSD light receiving surface even if there is a positional deviation, and the optical scanning unit 10 becomes large. Since the original feature of the optical scanning device 1 of the fourth embodiment is that the optical scanning unit 10 can be made compact, according to this modification, phase difference measurement and movement time measurement can be performed while keeping the feature. , It is possible to display an appropriate image.

Next, a second modification of the fourth embodiment will be described. In the second embodiment, the wavelength of the light received by the photodetector 110 is not particularly limited. In the second embodiment, for example, light in the visible light range, which is a mixture of red, green, and blue colors, may be received. However, in that case, if the displayed image is black in the entire area, it becomes impossible to measure the phase difference and the moving time. This modification is an embodiment for solving this problem.

In the second modified example, the laser of the infrared wavelength provided in the light source unit 1101 is turned on at all times (that is, while displaying an image). Further, the photodetector 110 selectively receives only infrared light. This means that the photodetector 110 may be sensitive only to infrared light, or the photodetector 110 may have an optical filter that passes only infrared light.

As a result, it is possible to measure the phase difference and the moving time during image display by using light having a wavelength that cannot be visually recognized by human eyes. Since infrared light continues to be radiated even during a period in which the displayed image is black in all areas, phase difference measurement and movement time measurement are possible. Therefore, a good image can be displayed even at the timing when the image to be displayed is black in the entire area and is switched to any image.

In the above description, the laser having the infrared wavelength is always turned on. However, since it is the timing when the light spot passes the split axis of the photodetector 110 that is detected by the differential signal, the timing It may be turned on only before and after, and turned off during other periods.

Further, a third modification of the fourth embodiment will be described. The second modification of the fourth embodiment has a configuration using an infrared laser, but in that case, an infrared laser needs to be mounted, which leads to an increase in cost. Therefore, in the present embodiment, it is possible to measure the phase difference and the moving time without using an infrared laser even when the displayed image is black in the entire area.

In the third modification, the blue laser provided in the light source unit 1101 is turned on only before and after the timing when the light spot passes through the split axis of the photodetector 110, and turned off during the other periods. The light emission control unit 22 of the present modification receives the gradation data (R, G, B) supplied from the display image storage memory 33, and controls the laser light emission based on the grayscale data (R, G, B). Before and after the timing of passing the division axis of 110, the blue laser is always emitted regardless of the value of the gradation data (R, G, B). At that time, the emission intensity of the blue laser has a sufficiently low luminance.

This modification utilizes the fact that among the three colors of red, green, and blue, the human eye has the lowest sensitivity to blue. According to this modification, the blue laser is caused to emit light with a low luminance only at the minimum timing required to perform the phase difference measurement and the moving time measurement. As a result, it is possible to measure the phase difference and the moving time during the display of the image without being visually recognized by the human eye. Even during the period in which the displayed image is black in the entire area, the phase difference measurement and the movement time measurement can be performed. Therefore, the same effect as the second modification of the second embodiment can be realized without using the infrared laser.

A fourth modification of the fourth embodiment will be described. This modification is different from the second embodiment only in the configuration of the optical scanning unit. The optical scanning unit in this modification is denoted by reference numeral 13. The configuration is the same as that of the second embodiment except that the light scanning unit 10 of the second embodiment is replaced with the light scanning unit 13.

FIG. 28 shows the structure of the optical scanning unit 13 of this modification. In the configuration of the second embodiment, the position where the prism 109 is arranged is ahead of the lens 104, but in this modification, it is before the lens 104. When the light guide path 102 is a fiber, the light emitted from the fiber is not parallel light but diffused light. Therefore, the light spot on the photodetector 110 has an area as in the second embodiment. Therefore, even with the configuration of this modification, the same phase difference measurement and movement time measurement as in the second embodiment can be performed.

A fifth modification of the fourth embodiment will be described. This modification is a configuration for use in a head mounted display, and is different from the second embodiment only in the configuration of the optical scanning unit. The optical scanning unit in this modification is denoted by reference numeral 14. The configuration of the optical scanning device is the same as that of the second embodiment except that the optical scanning unit 10 of the second embodiment is replaced with the optical scanning unit 14. Further, the optical scanning device of this modification is used in combination with the light guide plate 15. The light guide plate 15 may be considered to be included in the optical scanning device 2.

The optical scanning unit 14 and the light guide plate 15 of this modification will be described with reference to FIG. The optical scanning unit 14 has the same configuration as that of the second embodiment shown in FIG. 2 except that the prism 109 and the photodetector 110 are excluded from the optical scanning unit 14.

The light guide plate 15 includes a first deflecting unit 151 that reflects the light incident on the light guide plate 15 so that the light is totally reflected inside the light guide plate 15, and the light that is totally reflected inside the light guide plate 15 of the observer's pupil 71. It includes a second deflecting portion 152 that emits toward. The first deflecting unit 151 is composed of, for example, a light reflecting film. The present inventors have found that in such a light guide plate, not only the light L1 reflected by the first deflecting unit 151 but also the light L2 passing through the first deflecting unit 151 exists.

In this modification, the photodetector 110 is arranged in front of the light guide plate 15 so as to receive the light L2 passing through the first deflecting unit 151. That is, the photodetector 110 is arranged in a straight line between the light guide path 102 and the incident portion of the light guide plate 15. Both the prism 109 of the second embodiment and the first deflecting unit 151 of the present modification are common in that the incident light is split into the image display light and the detection light for the present invention. is there. That is, with the configuration of this modification, the same effect as that of the second embodiment can be realized.

Next, a sixth modification of the fourth embodiment will be described. FIG. 31 shows a locus of displacement of the emission end 102a of the light guide path 102. The range indicated by A is a predetermined effective range and corresponds to the area for displaying the image. In the configuration of the fourth embodiment, the laser is turned off outside the effective range A, but in the present modification, the laser is turned on before and after the regions indicated by B1, B2, B3, and B4 in FIG. The intensity of laser lighting in this region does not depend on the gradation data (R, G, B) output from the display image storage memory 33, and light is emitted with high brightness. This light is called detection light. Light outside the effective range A is shielded by a mechanical structure (not shown) after passing through the lens 111.

As can be seen from comparison with FIG. 30, these regions B1 to B4 are found to correspond to the scanning trajectory before and after passing through the division axis of the photodetector 110. That is, the phase difference measurement in the first embodiment can be performed by emitting the detection light in the areas B1 to B4. This makes it possible to detect whether or not it is in a resonance state. Although the differential signal is normalized, the S/N is more advantageous as the emission brightness is higher. Since the emission intensity in the regions B1 to B4 in this modification has high brightness without depending on the gradation data (R, G, B), more accurate phase difference measurement is performed as compared with the fourth embodiment. Will be possible.

As described above, while the image is being displayed (that is, after step S1006, the state is not Yes in step S1012), the image display or the image capturing is performed during a period in which the scanning locus is within the predetermined region. Then, the light emission control unit 22 emits the detection light during the period when the scanning locus is not in the predetermined region. Then, it is possible to generate a differential signal with respect to the detection light and measure the phase difference. As a result, more accurate phase difference measurement can be performed, and the drive frequency can be made to follow the change in the resonance frequency with high accuracy. The second to fifth modified examples of the fourth embodiment described above can be similarly applied to the first embodiment.

As described above, according to the fourth embodiment, it is possible to properly display an image in the optical scanning device having a function of displaying an image.

Next, the configuration of the optical scanning device of the fifth embodiment will be described.
In the above-described embodiment, the four-division photodetector is used to detect the timing of passing through the division axis. However, the four-division photodetector may not be used. Example 5 is an embodiment in which a four-division photodetector is not used.

FIG. 32 shows the structure of the optical scanning unit 17 of the fifth embodiment. The same components as those in FIG. 2 which is the configuration diagram of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. The reflector 112a and the reflector 112b are attached to the lens 104, and reflect a part of the emitted light when displaying an image. The detection waveguide 113a and the detection waveguide 113b take in the light reflected by the reflector 112a and the reflector 112b. The detection waveguide 113 is, for example, a single mode or multimode optical fiber.

The reflector and the light guide path for detection are also arranged in a direction perpendicular to the paper surface. FIG. 33A shows the positional relationship between the lens 104 and the reflectors 112a, 112b, 1112c, 112d. Further, FIG. 33B is a cross-sectional view of the optical scanning unit 17, showing a positional relationship between the detection light guide paths 113a, 113b, 113c, 113d.

As is clear from FIG. 32, when the origin of the xy plane is taken as the center of the vibrating portion 101, the reflector and the detection waveguide are arranged on the x axis and the y axis. As a result, the amount of light received by the detection light guide path becomes maximum at the timing when the scanning locus of light passes through the x-axis and the y-axis.

The optical scanning device of the fifth embodiment has a peak detection circuit (not shown). The peak detection circuit detects the timing at which the amount of received light becomes maximum for each of the detection light guide paths. A signal is output that is the logical sum of the timing at which the amount of received light at the detection light guide path 113a is maximized and the timing at which the amount of received light at the detection light guide path 113b is maximized. This signal has the same waveform as that shown in FIG. That is, it becomes a signal equivalent to the output signal of the logical sum circuit 2306 of the phase difference measuring unit 23 in the first embodiment. Similarly, the peak detection circuit 32 also outputs a signal that is the logical sum of the timing when the amount of received light in the detection light guide path 113c is maximum and the timing when the amount of received light in the detection light guide path 113d is maximum. This signal has the same waveform as that shown in FIG. That is, it becomes a signal equivalent to the output signal of the logical sum circuit 2313 of the phase difference measuring unit 23 in the first embodiment.

As described above, according to the configuration of the fifth embodiment, it is possible to generate the same signal without using the four-division photodetector. The phase difference measuring circuit 28 of the fifth embodiment differs from the phase difference measuring circuit 28 of the first embodiment shown in FIG. 14 in that the zero-cross detection circuit 232 and the zero-cross detection circuit 234 are eliminated and the two output signals of the peak detection circuit are connected instead. Good. Thereby, the same effect as that of the first embodiment can be obtained.

Next, a modification of the fifth embodiment will be described. FIG. 34 shows the structure of the optical scanning unit 18 of this modification. 32, which is the structure of the fifth embodiment, is the detection light guide paths 114a, 114b, 114c, and 114d. The detection light guide paths 113c and 113d are not shown in the same manner as in FIG. 39, but are arranged in four directions as in FIG. 33(a).

The detection light guide paths 114a, 114b, 114c, 114d are tapered optical fibers, and are arranged so that their tapered cross sections face the directions of the reflectors 112a, 112b, 112c, 112d as shown in FIG. Thereby, the amount of light received by the detection light guide path can be improved. As a result, the S/N is improved and more accurate phase difference measurement can be performed.

Next, the configuration of the optical scanning device of the sixth embodiment will be described.
In the above embodiments, the timing of passing the split axis is detected, but the method of detecting the shift of the resonance frequency or the shift of the scanning locus of light is not limited to the detection of the timing of passing the split axis.

Example 6 is an embodiment in which the deviation of the resonance frequency and the deviation of the scanning locus of light are detected by another method based on the configuration of Example 4. FIG. 35 is a block diagram showing the optical scanning device 4 including the optical scanning unit 16. The same components as those in FIG. 1, which is the block diagram of the first embodiment, are designated by the same reference numerals, and the description thereof will be omitted. The difference in configuration from the first embodiment is that the optical scanning unit 19, the differential signal generating unit 32, and the phase difference measuring unit 23 are omitted, and the signal from the photodetector 115 provided in the optical scanning unit 19 is a controller. 40 is input.

FIG. 36 shows the structure of the optical scanning unit 19 of this modification. The difference from the fourth embodiment is the photodetector 115 and the condenser lens 116. FIG. 37 shows the structure of the photodetector 115. The dotted line in FIG. 37 illustrates an ideal scanning locus of light projected on the photodetector 115. The range indicated by A is a predetermined effective range, and corresponds to the area for displaying a video. The photodetector 115 of the sixth embodiment has a light receiving surface only in the regions C1, C2, C3, and C4. In an ideal state (that is, a state in which drive parameters such as resonance frequency are appropriately set), the laser is turned on at the timing when the center of the light spot is located within the regions C1, C2, C3, and C4. Hereinafter, this timing is referred to as "predetermined timing on the scanning locus".

When the drive frequency matches the resonance frequency, the scanning trajectory of the light projected on the photodetector 115 matches the dotted line in FIG. 37, so if the laser is emitted at a predetermined timing on the scanning trajectory, Light is detected on all four light-receiving surfaces.

On the other hand, when the drive frequency does not match the resonance frequency, for example, the amplitude decreases, so that even if the laser is emitted at the predetermined timing on the scanning locus, light is not detected on all four light receiving surfaces. Further, when the scanning locus of the light is deviated, the light is detected only on some of the four light receiving surfaces, or the timing at which the light is detected deviates from the predetermined timing on the scanning locus.

That is, even with the configuration like the photodetector 115 of the sixth embodiment, it is possible to detect the shift of the resonance frequency and the shift of the scanning locus of light. For example, when the deviation of the resonance frequency is detected, the image display may be interrupted and the resonance frequency may be changed. Further, when the deviation of the scanning locus of light is detected, the magnification in the first variable gain 2005, the magnification in the second variable gain 2006, and the phase difference _{Δθ drv} of the second sine wave may be changed. .. In the state in which the parameters of these drive signals have been changed and proper image display is being performed, light is detected on all four light receiving surfaces. Therefore, it is possible to detect whether or not an appropriate image display is being performed.

Even in the case of the sixth embodiment, it is possible to monitor the deviation of the resonance frequency and the deviation of the scanning locus of light while displaying the image (in other words, without interrupting the display of the image). it can.

In the case of the sixth embodiment, the timing at which the deviation of the resonance frequency is detected by the photodetector is not during the display or the image pickup of the image, but the light for the image display or the image pickup is performed. It can be said that the scanning is being performed.

In the sixth embodiment, the photodetector 115 has been described with the configuration shown in FIG. 37, but various modifications can be considered in the configuration of the photodetector.

For example, the light receiving surface of the photodetector 115 may be areas C5 and C6 along the sides of the area A for displaying an image, as shown in FIG. Alternatively, as shown in FIG. 39, the photodetector 115 may have a structure having a light receiving surface in the regions D1, D2, D3, and D4. As can be seen by comparing FIGS. 39 and 30, the regions D1, D2, D3, and D4 are along the division axis of the photodetector 110 of the fourth embodiment. Therefore, it is possible to detect the timing of passing through the areas D1, D2, D3, and D4 and the moving speed when passing through the areas D1, D2, D3, and D4, which are wide. That is, similarly to the first and second embodiments, it is possible to detect the deviation of the resonance frequency and the deviation of the scanning locus of light and appropriately correct the deviation.

Further, the light receiving surface of the photodetector 115 may be a linear line sensor having an oblique angle of 45°, which is obtained by combining the areas D1 and D3 in FIG. Even in that case, since the timing of passing through the line sensor can be detected, the deviation of the resonance frequency can be detected and appropriately corrected as in the first embodiment.

Alternatively, the photodetector 115 may be a PSD. In the case of PSD, since the light scanning locus itself can be detected, the resonance frequency deviation or the light scanning locus deviation can be detected and appropriately corrected as in the first and second embodiments.

The photodetector in the sixth embodiment and its modified example is a photodetector having a small light receiving surface area, or a PSD in which position detection cannot be performed when a part of a light spot goes out of the light receiving surface. I'm using it. In these configurations, by providing the condenser lens 116 to reduce the light spot, more accurate detection becomes possible. Therefore, in Example 6 and its modification, it is preferable to provide the condenser lens 116 before the light L2 deflected by the prism 109 reaches the photodetector 115.

The optical scanning device in the above-described embodiment has at least the function of displaying an image. The present invention can be similarly applied to the case where the image capturing function is provided. The effect in that case is that the resonance state of the light guide path 102 can be maintained and appropriate image pickup can be continued without interrupting image pickup. Of the effects of the present invention, it is clear that the same effects can be obtained in the case of image capturing, except for the effects specific to image display.

Further, the scanning method for performing the dot shift correction processing has been described in the case of the first and second embodiments, but the loci of optical scanning are not limited to these. In addition, the trajectory of optical scanning is not limited to the above when maintaining the resonance state by measuring the phase difference or estimating the trajectory of optical scanning by measuring the moving speed. A feature common to these is that resonance is used for both the X axis and the Y axis. Therefore, the drive signals for both axes have a common frequency component.

Further, although the angle correction unit 2101 and the coordinate calculation unit 2102 have been described by dividing the blocks for the sake of explanation, they may be the same. This is clear from the fact that it is possible to carry out the operation in which (Equation 7) to (Equation 10) are put together in one block.

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications other than the above-described modifications are included. For example, the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of a certain embodiment. Further, with respect to a part of the configuration of each embodiment, other configurations can be added/deleted/replaced.

Further, each of the above-described configurations, functions, processing units, processing means, etc. may be realized by hardware by designing a part or all of them with, for example, an integrated circuit. Further, the above-described respective configurations, functions and the like may be realized by software by a processor interpreting and executing a program for realizing each function. Information such as a program, a table, and a file that realizes each function can be placed in a memory, a hard disk, a recording device such as an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, and a DVD.

In addition, the control lines and information lines shown are those that are considered necessary for explanation, and not all the control lines and information lines on the product are necessarily shown. In practice, it may be considered that almost all configurations are connected to each other.

DESCRIPTION OF SYMBOLS 1... Optical scanning device 10... Optical scanning part 11... Illumination part 12... Light receiving part 20... Drive signal generation part 21... Remapping control part 22... Emission control part 23... Phase difference measuring part 24... Moving time measuring part 33... Display Image storage memory 40... Controller 41... Storage unit 42... Input/output control circuit 50... External control device 70... Head mount display 71... Pupil 101... Vibrating unit 102... Light guide path 103... Adhesive unit 104... Lens 105... Housing 106... Support member 107...Electrical wiring 108...Demultiplexing unit 109...Prism 110...Photodetector

Claims (20)

An optical scanning device for displaying or picking up an image by using emitted light,
A light guide path that guides the incident light and emits the emitted light from the emission end,
A vibrating portion that vibrates the emission end so that the emission light repeatedly draws a predetermined scanning locus,
A light emission control unit for controlling the emission of the emitted light,
A photodetector for detecting a part of the emitted light,
A scanning coordinate generation unit that generates scanning coordinates related to the predetermined locus,
As a drive signal for driving the vibrating unit corresponding to the scanning coordinates, a drive signal generation unit that generates a sine wave whose amplitude is modulated,
A coordinate calculation unit that calculates the coordinates of the image using the scanning coordinates and outputs the coordinates as image coordinates,
At least one of the radius of the image coordinates and the argument of the image coordinates depends on the radius of the scanning coordinates and the argument of the scanning coordinates. The optical scanning device according to claim 1, wherein
The coordinate calculator is
The image coordinates are calculated by performing a predetermined calculation for correcting the distortion on the scanning coordinates,
The optical scanning device, wherein the predetermined calculation is a function that takes a radius of the scanning coordinate and a deviation angle of the scanning coordinate as arguments. The optical scanning device according to claim 1, wherein
The vibrating part has two drive shafts,
The amplitude modulation of the drive signal with respect to the two drive axes is different,
A calculation for correcting the angle based on the scanning coordinates is further provided, and an angle correction unit for outputting the correction angle is further provided,
The coordinate calculator is
Output the image coordinates by calculating the image coordinates using the correction angle,
When the deflection angle of the scanning coordinates is θdrv and the correction angle is θcalc, the calculation relating to the correction angle is represented by the following mathematical expression:
θcalc=θdrv+f(θdrv, rdrv)+C
The optical scanning device, wherein the function f(θ, r) is a periodic function of a period π [rad] with respect to θ. The optical scanning device according to claim 1, wherein
The vibrating part has two drive shafts,
The amplitude modulation of the drive signal with respect to the two drive axes is different,
A calculation for correcting the angle based on the scanning coordinates is further provided, and an angle correction unit for outputting the correction angle is further provided,
The coordinate calculator is
Output the image coordinates by calculating the image coordinates using the correction angle,
When the deflection angle of the scanning coordinates is θdrv and the correction angle is θcalc, the calculation relating to the correction angle is represented by the following mathematical expression:
θcalc=f(θdrv, rdrv)+C
An optical scanning device, wherein the constant C is adjusted using a detection signal detected by the photodetector. An optical scanning device for displaying or picking up an image by using emitted light,
A light guide path that guides the incident light and emits the emitted light from the emission end,
A vibrating portion that vibrates the emission end so that the emission light repeatedly draws a predetermined scanning locus,
A light emission control unit for controlling the emission of the emitted light,
A photodetector for detecting a part of the emitted light,
As a drive signal for driving the vibrating section, a drive signal generating section that generates a sine wave whose amplitude is modulated,
And a control unit that performs predetermined control,
The control unit is
Optical scanning characterized by instructing a change of a drive parameter of the drive signal in accordance with a detection signal detected by the photodetector during a period of performing the optical scanning for displaying the image or performing the imaging. apparatus. The optical scanning device according to claim 5, wherein
A display image storage unit for storing a display image,
A coordinate calculation unit for calculating the coordinates of the image based on a predetermined calculation and outputting as image coordinates,
The light emission control unit,
Controlling the emission of the emitted light based on the image coordinates output by the coordinate calculation unit and the display image read from the display image storage unit;
The control unit estimates the scanning locus of the emitted light using the detection signal,
The optical scanning device, wherein the predetermined calculation in the coordinate calculation unit changes according to a signal from the control unit. The optical scanning device according to claim 5, wherein
A light-receiving unit that detects return light of the emitted light emitted from the emission end of the light guide path,
A coordinate calculation unit for calculating the coordinates of the image based on a predetermined calculation and outputting as image coordinates,
The control unit is
Information related to the return light detected by the light receiving unit based on the image coordinates output by the coordinate calculation unit is taken as an imaged image, and the scanning locus of the emitted light is estimated using the detection signal,
The optical scanning device, wherein the predetermined calculation in the coordinate calculation unit changes according to a signal from the control unit. The optical scanning device according to claim 5, wherein
The photodetector is
An optical scanning device, wherein as the detection signal, a part of light during the display or the image pickup of the image is detected. The optical scanning device according to claim 5, wherein
The optical scanning device, wherein the drive parameter is a frequency of the sine wave. The optical scanning device according to claim 5, wherein
An optical scanning device, wherein the photodetector has two or more light receiving surfaces. The optical scanning device according to claim 5, wherein
The photodetector has a structure in which two or more light receiving surfaces are adjacent to each other,
At least one of the sides separating the adjacent light receiving surfaces corresponds to an axis on which the vibrating section vibrates. The optical scanning device according to claim 5, wherein
The photodetector has a structure in which two or more light receiving surfaces are adjacent to each other,
The intensity center of the light detected in the photodetector further comprises a phase difference measuring unit for detecting the timing of passing a side separating the adjacent light receiving surfaces,
The control unit is
The optical scanning device is configured to instruct to change the drive parameter so that the phase of the sine wave at the timing detected by the phase difference measuring unit becomes a predetermined phase. The optical scanning device according to claim 5, wherein
The photodetector has a structure consisting of four adjacent light-receiving surfaces,
A moving time measuring unit for measuring a moving speed when the intensity center of light detected by the photodetector passes through a side separating the adjacent light receiving surfaces,
The intensity center of the light detected in the photodetector further has a phase difference measuring unit for detecting the timing of passing a side separating the adjacent light receiving surfaces,
The control unit is
An optical scanning device, wherein the scanning locus is estimated based on the timing and the moving speed. The optical scanning device according to claim 5, wherein
The photodetector has a structure consisting of four adjacent light-receiving surfaces,
When the signals from the four light receiving surfaces are A, B, C and D,
The detection signal is
An optical scanning device characterized by being a first differential signal D1 represented by Formula 1 or a second differential signal D2 represented by Formula 2.

The optical scanning device according to claim 5, wherein
A prism that branches a part of the emitted light and guides it to the photodetector,
A lens for enlarging and projecting the emitted light emitted from the light guide path,
The prism is
An optical scanning device, characterized in that a part of the emitted light before passing through the lens or a part of the emitted light after passing through the lens is branched. The optical scanning device according to claim 5, wherein
The emitted light emitted from the light guide path is further incident from a predetermined incident part, and further has a light guide plate that emits toward the observer's pupil.
The photodetector is
An optical scanning device, which is arranged on a straight line connecting the light guide path and an incident portion of the light guide plate. The optical scanning device according to claim 5, wherein
Further having a detection light guide path for capturing a part of the emitted light,
The photodetector is
An optical scanning device, which detects light propagating from the detection light guide path. The optical scanning device according to claim 5, wherein
The control unit is
Displaying or picking up the image in a period in which the scanning locus is within a predetermined area,
The light emission control unit,
Emitting the emitted light in a period in which the scanning locus is not the predetermined region,
The optical scanning device, wherein the detection signal is a signal in which the photodetector detects the emitted light. The optical scanning device according to claim 5, wherein
The emitted light includes detection light having a wavelength not visible light or a wavelength of blue,
The optical scanning device, wherein the photodetector selectively detects light having a wavelength of the detection light. A light guide path that guides incident light to emit the emitted light from the emission end, a vibrating portion that vibrates the emission end so that the emission light repeatedly draws a predetermined scanning locus, and controls emission of the emission light. A light emission control unit, a photodetector that detects a part of the emitted light, a drive signal generation unit that generates a sine wave whose amplitude is modulated as a drive signal for driving the vibration unit, and a predetermined control. An optical scanning method for displaying or picking up an image by the emitted light using an optical scanning device having a control unit for performing,
The control unit is
Starting displaying or capturing the image,
A step of determining whether or not it is necessary to change a drive parameter of the drive signal using a detection signal detected by the photodetector during a period of performing optical scanning for displaying or capturing the image; ,
A step of instructing to change a drive parameter of the drive signal according to a result of the determination;
An optical scanning method comprising:

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