WO2011108395A1 - Optical scanning device and image display device provided with the same - Google Patents

Optical scanning device and image display device provided with the same Download PDF

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Publication number
WO2011108395A1
WO2011108395A1 PCT/JP2011/053788 JP2011053788W WO2011108395A1 WO 2011108395 A1 WO2011108395 A1 WO 2011108395A1 JP 2011053788 W JP2011053788 W JP 2011053788W WO 2011108395 A1 WO2011108395 A1 WO 2011108395A1
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WO
WIPO (PCT)
Prior art keywords
frequency
amplitude
drive signal
resonance
deflection
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Application number
PCT/JP2011/053788
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French (fr)
Japanese (ja)
Inventor
政敏 神山
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ブラザー工業株式会社
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Application filed by ブラザー工業株式会社 filed Critical ブラザー工業株式会社
Publication of WO2011108395A1 publication Critical patent/WO2011108395A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
    • G02B26/10—Scanning systems
    • G02B26/101—Scanning systems with both horizontal and vertical deflecting means, e.g. raster or XY scanners
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
    • H04N1/113—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using oscillating or rotating mirrors
    • H04N1/1135—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using oscillating or rotating mirrors for the main-scan only

Definitions

  • the present invention relates to an optical scanning device and an image display device including the same, and more specifically, by a resonance type deflection element having a deflection surface for deflecting an incident light beam and swinging around the axis by resonance.
  • the present invention relates to an optical scanning device that scans a light beam and an image display device including the same.
  • an optical scanning device that scans a light beam having an intensity corresponding to an image signal in a one-dimensional direction or a two-dimensional direction.
  • Such an optical scanning device scans a light beam having an intensity corresponding to an image signal in a two-dimensional direction and projects it onto at least one retina of a user, and displays an image
  • an image display device such as a screen scanning type image display device that displays an image on a screen by scanning a light beam having an intensity corresponding to a signal in a two-dimensional direction.
  • a resonant deflection element that can swing the reflection mirror at a relatively high speed and a non-resonance deflection element that can swing the reflection mirror at a relatively low speed
  • the light beam emitted from the light source with the intensity corresponding to the image signal is scanned in the first direction by resonating the reflection mirror of the resonance type deflection element, and the reflection mirror of the non-resonance type deflection element is sawtooth wave or triangular wave Or it drives by trapezoid wave shape and scans a light beam to a 2nd direction, and displays an image.
  • the first direction is, for example, the horizontal direction
  • the second direction is, for example, the vertical direction.
  • the deflection surface of the resonance type deflection element is oscillated at a resonance frequency unique to the resonance type deflection element, whereby the deflection surface can be oscillated at low power consumption and at high speed.
  • the resonance frequency unique to the resonance type deflection element differs depending on the individual difference of the resonance type deflection element, it is necessary to detect the resonance frequency for each resonance type deflection element and drive the resonance type deflection element.
  • the resonance type deflection element has a jumping characteristic in which the oscillation amplitude of the deflection surface changes suddenly when the frequency is shifted. Therefore, if the resonant frequency of the resonant deflection element changes due to changes in the ambient temperature or the like, the oscillation amplitude (swing) of the deflection surface must be changed without changing the frequency of the drive signal for driving the resonant deflection element. There is a risk that the angle will be rapidly reduced. At this time, if the voltage of the drive signal is increased to maintain the deflection surface at a constant oscillation amplitude without changing the frequency of the drive signal, the deflection surface is oscillated at a position deviating from the resonance point. Therefore, the power consumption of the resonance type deflection element increases. Moreover, when the deflection surface is swung at a position deviating from the resonance point, a large swing amplitude cannot be obtained.
  • the present invention provides an optical scanning device capable of maintaining a deflection surface at a constant oscillation amplitude even when the resonance frequency of a resonance type deflection element changes due to a change in ambient temperature or the like, and an image display device including the same.
  • the purpose is to provide.
  • a resonance type deflection element having a deflection surface for deflecting an incident light beam, the deflection surface oscillating around an axis by resonance, and the resonance type deflection device.
  • the frequency of the drive signal for driving the element is changed, the oscillation amplitude of the deflection surface is detected, the resonance frequency unique to the resonance-type deflection element is determined, and the drive at a frequency shifted from the resonance frequency by a predetermined frequency
  • Drive means for changing the amplitude of the drive signal to drive the swing amplitude of the deflection surface to a predetermined value after driving the resonant deflection element with a signal.
  • the resonant deflection element is a MEMS in which a region including the deflection surface is formed on a metal substrate, and the driving means has the drive having a frequency higher than the resonance frequency by a predetermined frequency.
  • the swing amplitude of the deflection surface may be set to a predetermined value.
  • the resonant deflection element is a MEMS in which a region including the deflection surface is formed on a silicon substrate, and the drive means has the drive having a frequency lower than the resonance frequency by a predetermined frequency.
  • the swing amplitude of the deflection surface may be set to a predetermined value.
  • the optical scanning device may further include a temperature detection unit that detects a temperature of the resonant deflection element or its surroundings, and the predetermined frequency may be a frequency based on a temperature detected by the temperature detection unit.
  • a retinal scanning type image display that includes the optical scanning device and displays an image by scanning a light beam having an intensity corresponding to an image signal with the optical scanning device and emitting the light beam toward at least one eye of a user. It is good also as an apparatus.
  • the amplitude level of the drive signal is changed to set the swing amplitude of the deflection surface to a predetermined value. Even when the resonance frequency of the resonant deflection element changes due to a change in ambient temperature or the like, the deflection surface can be maintained at a constant oscillation amplitude.
  • the optical scanning device 1 includes a drive control unit 10, a DC voltage superimposing unit 40, a resonant deflection element 50, a light source 60, and a BD sensor 70.
  • the drive control unit 10 is a drive unit that generates a drive signal Sig1 that drives the resonant deflection element 50, and includes a frequency determination unit 11, an amplitude determination unit 12, and a drive signal generation unit 13.
  • the drive signal generation unit 13 generates and outputs a drive signal Sig1 having the frequency fo and the amplitude Vp determined by the frequency determination unit 11 and the amplitude determination unit 12.
  • the DC voltage superimposing unit 40 includes a DC voltage applying unit 41 and a signal superimposing circuit 42. Then, the direct current voltage generated by the direct current voltage application unit 41 is superimposed on the drive signal Sig 1 output from the drive control unit 10 by the signal superimposing circuit 42 and applied to the drive unit 51 of the resonant deflection element 50. .
  • the deflection surface 52 of the resonant deflection element 50 swings based on the drive signal Sig1 superimposed on the DC voltage.
  • the drive part 51 is comprised by the piezoelectric element etc., for example.
  • the resonant deflection element 50 is a MEMS formed on a thin plate-like metal substrate, and has, for example, a shape as shown in FIG.
  • the metal substrate include an aluminum substrate, a copper substrate, and an iron substrate.
  • the resonant deflection element 50 includes a drive unit 51, a deflection surface (reflection mirror) 52, a frame body 53, and beam portions 54 and 54. Then, the drive signal Sig1 superimposed on the DC voltage is applied to the drive unit 51. Due to the displacement of the drive unit 51, the frame body 53, the beam portions 54 and 54, the deflection surface 52, and the frequency at the frequency according to the drive signal Sig1.
  • the deflection surface 52 swings about the axis about the swing axis Lc.
  • the swing amplitude of the deflection surface 52 is a rotation angle range of the deflection surface 52 and is a deflection angle of the deflection surface 52.
  • FIG. 3 shows the oscillation amplitude characteristics of the deflection surface 52 of the resonant deflection element 50 when a drive signal Sig1 having a predetermined amplitude is inputted at a certain temperature while changing its frequency.
  • a drive signal Sig1 having a predetermined amplitude is inputted at a certain temperature while changing its frequency.
  • FIG. 3 shows the oscillation amplitude characteristics of the deflection surface 52 of the resonant deflection element 50 when a drive signal Sig1 having a predetermined amplitude is inputted at a certain temperature while changing its frequency.
  • the resonance frequency fs unique to the resonance type deflection element 50 is determined while changing the frequency of the drive signal Sig1 having a predetermined amplitude, and from the resonance frequency fs as shown in FIG.
  • the resonant deflection element 50 is driven by a drive signal Sig1 having a frequency fo that is higher by a predetermined frequency ⁇ f.
  • the oscillation amplitude of the deflecting surface 52 is increased. It can be suppressed from becoming smaller. That is, by setting the frequency fo of the drive signal Sig1 to a frequency that is higher by a predetermined frequency ⁇ f than the resonance frequency fs inherent to the resonance type deflection element 50, a margin can be taken against a characteristic change due to a temperature change or the like.
  • FIG. 7 is a diagram showing the characteristics of the resonant deflection element 50 for each amplitude Vp (5V, 7V, 11.5V, 13V) of the drive signal Sig1.
  • Vp amplitude of the drive signal Sig1
  • the resonance frequency fs of the resonance type deflection element 50 also varies. Therefore, if the amplitude Vp of the drive signal Sig1 is changed after the frequency of the drive signal Sig1 is determined, the swing amplitude of the deflection surface 52 changes.
  • the amplitude of the drive signal Sig1 is increased to some extent, the frequency fo is determined, and then the amplitude Vp is changed. By doing so, it is possible to suppress the swing amplitude of the deflection surface 52 from rapidly decreasing due to the amplitude change of the drive signal Sig1.
  • the frequency of the drive signal Sig1 is adjusted more accurately by adjusting the frequency of the drive signal Sig1 based on the phase difference ⁇ c between the signal waveform of the drive signal Sig1 and the oscillation waveform of the deflection surface 52.
  • the deflection surface 52 is swung. That is, after determining the frequency fo of the drive signal Sig1 and adjusting the swing amplitude of the deflection surface 52 to a predetermined amplitude as described above, when the phase difference ⁇ c is out of the predetermined range Z (see FIG. 8), The frequency of the drive signal Sig1 is adjusted so that the phase difference ⁇ c is within the predetermined range Z.
  • the amplitude Vp of the drive signal Sig1 is changed in order to keep the swinging amplitude of the deflection surface 52 constant, it is performed after confirming that the phase difference ⁇ c is within the predetermined range Z. That is, the frequency control based on the phase difference ⁇ c is performed with priority over the amplitude control. In this way, the deflection surface 52 can be oscillated with higher accuracy.
  • the optical scanning device 1 is configured as described above, it is possible to suppress the swing amplitude of the deflecting surface 52 from rapidly decreasing due to the jump phenomenon, and to resonate in accordance with the environmental change of the optical scanning device 1.
  • the mold deflection element 50 can be driven.
  • the frequency determining unit 11, the amplitude determining unit 12, the drive signal generating unit 13, and the DC voltage superimposing unit 40 are configured as follows.
  • the frequency determination unit 11 detects the resonance frequency fs unique to the resonance type deflection element 50 and determines a frequency higher than the resonance frequency fs by a predetermined frequency ⁇ f as the frequency fo of the drive signal Sig1. Thereafter, when the phase difference ⁇ c between the drive signal Sig1 and the oscillation state of the resonant deflection element 50 exceeds a predetermined range, the frequency determination unit 11 changes the frequency fo of the drive signal Sig1, and the phase difference ⁇ c is Within a predetermined range Z.
  • the frequency determination unit 11 includes a phase difference determination unit 21, a target phase difference storage unit 22, a phase difference comparison unit 23, and a frequency change control unit 24.
  • the phase difference determination unit 21 determines the phase difference ⁇ c between the signal waveform of the drive signal Sig1 and the swing waveform of the deflection surface 52.
  • the BD sensor 70 receives a light beam emitted from the light source 60 when the deflecting surface 52 is at a predetermined tilt angle, and outputs a detection signal (hereinafter referred to as a BD signal).
  • the phase difference determination unit 21 detects the tilt angle state of the deflection surface 52 based on the output timing of the BD signal from the BD sensor 70, and the phase difference ⁇ c between the waveform of the drive signal Sig1 and the swing waveform of the deflection surface 52. Determine.
  • phase difference determination unit 21 for example, when the tilt angle of the deflecting surface 52 goes from + X to -X, the timing when the tilt angle becomes 0 and when the drive signal Sig1 goes from a positive voltage to a negative voltage, It is also possible to detect the timing when it becomes 0 V and determine the phase difference ⁇ c from the relationship between these timings. It is assumed that the inclination angle of the deflection surface 52 is in the + X direction when a positive voltage drive signal is applied to the drive unit 51.
  • the target phase difference storage unit 22 stores information on a predetermined range Z that is a range of the phase difference ⁇ c that can be activated.
  • the phase difference comparison unit 23 acquires the phase difference ⁇ c from the phase difference determination unit 21 and also acquires information on the predetermined range Z from the target phase difference storage unit 22, and whether or not the phase difference ⁇ c is within the predetermined range Z. Determine.
  • the frequency change control unit 24 outputs the phase difference ⁇ c from the phase difference determination unit 21 if the phase difference ⁇ c output from the phase difference determination unit 21 is larger than the upper limit value of the predetermined range Z when the phase difference ⁇ c is not within the predetermined range Z.
  • the drive signal generation unit 13 is controlled to increase the frequency of the drive signal Sig1 until the phase difference ⁇ c is smaller than the lower limit value of the predetermined range Z. Thereafter, the frequency change control unit 24 controls the drive signal generation unit 13 to lower the frequency of the drive signal Sig1 until the phase difference ⁇ c output from the phase difference determination unit 21 reaches 90 [deg].
  • the frequency of the drive signal Sig1 when the phase difference ⁇ c output from the phase difference determination unit 21 reaches 90 [deg] is the resonance frequency fs. Therefore, the frequency change control unit 24 determines the frequency of the drive signal Sig1 when the phase difference ⁇ c output from the phase difference determination unit 21 is 90 [deg] as the resonance frequency fs.
  • the frequency change control unit 24 has the phase difference determination unit 21.
  • the drive signal generator 13 is controlled to decrease the frequency of the drive signal Sig ⁇ b> 1 until the phase difference ⁇ c output from is reduced to 90 [deg]. Then, the frequency change control unit 24 determines the frequency of the drive signal Sig1 when the phase difference ⁇ c output from the phase difference determination unit 21 is 90 [deg] as the resonance frequency fs.
  • the frequency change control unit 24 determines the resonance frequency fs by increasing or decreasing the frequency of the drive signal Sig1. Then, the frequency change control unit 24 controls the drive signal generation unit 13 to output from the drive signal generation unit 13 a drive signal Sig1 having a frequency fo higher than the resonance frequency fs by a predetermined frequency ⁇ f.
  • the amplitude determination unit 12 controls the amplitude Vp of the drive signal Sig1 output from the drive signal generation unit 13 so that the swing amplitude of the deflection surface 52 of the resonant deflection element 50 becomes the target swing amplitude. And operates when the phase difference ⁇ c falls within the predetermined range Z.
  • the amplitude determination unit 12 includes an amplitude control execution switching unit 31, an amplitude determination unit 32, a target amplitude storage unit 33, an amplitude comparison unit 34, and an amplitude change control unit 35.
  • the amplitude control execution switching unit 31 controls the operation of the amplitude determination unit 32 based on the output from the phase difference comparison unit 23. That is, when the amplitude control execution switching unit 31 receives a signal output when the phase difference ⁇ c is within the predetermined range Z from the phase difference comparison unit 23, the amplitude control execution switching unit 31 sets the amplitude determination unit 32 to the non-operation state, and the phase difference ⁇ c is When the signal output when it is not within the predetermined range Z is received from the phase difference comparison unit 23, the amplitude determination unit 32 is put into an operating state.
  • the amplitude determination unit 32 detects the swing amplitude of the deflecting surface 52 based on the presence / absence and timing of the BD signal from the BD sensor 70 when the amplitude control execution switching unit 31 is brought into the operating state. Specifically, when the BD signal is not output from the BD sensor 70, the amplitude determination unit 32 determines that the swinging amplitude of the deflection surface 52 is within a predetermined range. Further, when the BD signal is output from the BD sensor 70, the swing amplitude of the deflection surface 52 is determined based on the interval of the BD signal output from the BD sensor 70.
  • the target amplitude storage unit 33 stores information on the swing amplitude (hereinafter referred to as swing amplitude Xa) of the target deflection surface 52.
  • the amplitude comparison unit 34 acquires information on the swing amplitude (hereinafter referred to as swing amplitude Xr) of the deflection surface 52 from the amplitude determination unit 32 and also acquires information on the swing amplitude Xa from the target amplitude storage unit 33. Then, an amplitude difference between the swing amplitude Xr and the swing amplitude Xa (hereinafter referred to as an amplitude difference Xs) is obtained.
  • the amplitude change control unit 35 controls the drive signal generation unit 13 to change the amplitude Vp of the drive signal Sig1 so that the amplitude difference Xs falls within a predetermined range.
  • the amplitude change control unit 35 does not change the amplitude Vp of the drive signal Sig1 when the amplitude difference Xs is within the predetermined range.
  • FIG. 9 is a simplified diagram for easy understanding.
  • the frequency determination unit 11 and the amplitude determination unit 12 output a drive signal Sig 1 having a predetermined frequency and amplitude from the drive signal generation unit 13. Then, the drive signal generation unit 13 is controlled (step S10). Specifically, the frequency change control unit 24 of the frequency determination unit 11 controls the drive signal generation unit 13 so that the drive signal Sig1 has a predetermined frequency. Further, the amplitude change control unit 35 of the amplitude determination unit 12 controls the drive signal generation unit 13 so that the drive signal Sig1 has a predetermined amplitude.
  • the predetermined frequency and amplitude are, for example, the frequency and amplitude set in advance in the frequency change control unit 24 and the amplitude change control unit 35 as defaults.
  • the frequency and amplitude when the frequency change control unit 24 and the amplitude change control unit 35 last controlled the drive signal Sig1 may be stored, and the frequency and amplitude may be set as a predetermined frequency and amplitude.
  • phase difference determination unit 21 determines the phase difference ⁇ c between the signal waveform of the drive signal Sig1 and the swing waveform of the deflection surface 52 (step S11).
  • the phase difference ⁇ c is compared with the predetermined range Z acquired from the target phase difference storage unit 22 in the phase difference comparison unit 23, and it is determined whether or not the phase difference ⁇ c is within the predetermined range Z (step S12). .
  • the frequency change control unit 24 detects the resonance frequency fs by increasing or decreasing the frequency of the drive signal Sig1, as described above. That is, the frequency change control unit 24 increases or decreases the frequency of the drive signal Sig1, and the frequency of the drive signal Sig1 when the phase difference ⁇ c output from the phase difference determination unit 21 becomes 90 [deg] is determined as the resonance frequency. It is determined as fs. Then, the frequency change control unit 24 controls the drive signal generation unit 13 to output from the drive signal generation unit 13 a drive signal Sig1 having a frequency fo that is higher than the resonance frequency fs by a predetermined frequency ⁇ f (step S13).
  • step S12 when the phase difference ⁇ c is within the predetermined range Z (step S12: Yes), based on the signal output from the frequency change control unit 24, the amplitude control execution switching unit 31 sets the amplitude determination unit 32 in the operating state, and the amplitude The determination unit 32 detects the swing amplitude of the deflection surface 52 (step S14). Then, the amplitude comparison unit 34 compares the swing amplitude Xr of the deflection surface 52 with the swing amplitude Xa of the target deflection surface 52 from the amplitude determination unit 32, and obtains an amplitude difference Xs thereof (step S15).
  • step S15 when the amplitude difference Xs is outside the predetermined range (step S15: No), the amplitude change control unit 35 controls the drive signal generation unit 13 so that the amplitude difference Xs is within the predetermined range, thereby driving signal Sig1. Is changed (step S16).
  • step S15 when the amplitude difference Xs is within the predetermined range (step S15: Yes), the drive control unit 10 is based on an input from the outside (for example, the operation unit). It is determined whether or not there is an end instruction (step S17). If there is an end instruction (step S ⁇ b> 17: Yes), the drive control unit 10 stops swinging of the deflection surface 52 of the resonant deflection element 50 and ends the driving process of the resonant deflection element 50. . On the other hand, if there is no end instruction (step S17: No), the process returns to step S11, and the processes from step S11 are repeated.
  • the frequency of the drive signal Sig1 for driving the resonance type deflection element 50 is changed, the oscillation state of the deflection surface 52 is detected, and the resonance type deflection element 50 is detected.
  • the inherent resonance frequency fs is determined.
  • the optical scanning device 1 drives the resonance type deflection element 50 with the drive signal Sig1 having a frequency shifted from the resonance frequency fs by a predetermined frequency ⁇ f, and then changes the amplitude Vp of the drive signal Sig1 to change the vibration of the deflection surface 52.
  • the dynamic amplitude is set to a predetermined value.
  • the optical scanning device 1 is configured in this way, it is possible to suppress the swing amplitude of the deflecting surface 52 from rapidly decreasing due to the jump phenomenon, and the resonant deflection element 50 due to a change in ambient temperature or the like. Even when the resonance frequency fs changes, the deflection surface 52 can be maintained at a constant oscillation amplitude.
  • the resonant deflection element 50 is a MEMS in which a region including a deflection surface 52 is formed on a metal substrate, and has characteristics as shown in FIG. That is, when the frequency of the drive signal Sig1 is made lower than the resonance frequency, the swing amplitude (swing angle) of the deflecting surface 52 is suddenly reduced, but even if the frequency of the drive signal Sig1 is increased from the resonance frequency. The swing amplitude (swing angle) of the deflecting surface 52 does not rapidly decrease. Therefore, the drive control unit 10 drives the resonant deflection element 50 with the drive signal Sig1 having a frequency fo that is higher than the resonant frequency fs by a predetermined frequency ⁇ f. In this way, even when the frequency of the drive signal Sig1 is not the same as the resonance frequency fs, the swing amplitude of the deflection surface 52 can be increased with a small drive signal Sig1, thereby saving power. be able to.
  • a line image sensor in which a plurality of photoelectric conversion elements are arranged in an array is provided at a position where a light beam scanned by the resonant deflection element 50 is incident.
  • the swinging state of the deflection surface 52 may be detected based on the output signal.
  • a new piezoelectric element is provided on the frame 53, and the swinging state of the deflection surface 52 is detected based on an electrical signal output from the piezoelectric element in response to the swinging of the deflection surface 52. You may do it.
  • a temperature detection unit 80 that detects the temperature of the resonant deflection element 50 or its surroundings is provided, and the predetermined frequency ⁇ f is changed according to the detection result by the temperature detection unit 80.
  • the frequency change control unit 24 stores a table associating the temperature T with the frequency, reads the frequency associated with the temperature T detected by the temperature detection unit 80 from the table, and sets the frequency to a predetermined value.
  • the frequency is ⁇ f.
  • the predetermined frequency ⁇ f can be appropriately determined according to the temperature, and even when the resonance frequency of the resonance-type deflection element changes due to a change in the ambient temperature or the like, the deflection surface 52 can be made more stable. A constant oscillation amplitude can be maintained.
  • the temperature detecting unit 80 corresponds to the temperature detecting means of the present invention.
  • the resonance type deflection element 50 is a MEMS in which a region including a deflection surface 52 is formed on a metal substrate
  • a MEMS in which a region including a deflection surface is formed on a silicon substrate may be used.
  • the resonant deflection element 50 ' is configured as shown in FIG.
  • the resonance type deflection element 50 ' has a reflecting mirror which is a deflection surface 52' having a quadrangular shape, and a reflecting surface is formed on the surface thereof.
  • the deflection surface 52 ' is supported by beam portions 54' and 54 'connected to two sides, and the beam portions 54' and 54 'are connected to and supported by a frame 53'.
  • the deflection surface 52 ' is supported by the frame 53' via the two beam portions 54 'and 54' so as to be swingable.
  • a drive unit 51 ′ made of a piezoelectric element extending from one corner of the frame 53 ′ toward the beam 54 ′ is formed on the frame 53 ′.
  • the deflection surface 52 ', the frame 53', and the beam portions 54 'and 54' are formed on the silicon substrate.
  • the drive signal Sig1 is superimposed on the direct current voltage from the drive control unit 10 and input to the drive unit 51 ′, so that the longitudinal direction of the beam portions 54 ′ and 54 ′ becomes the swing axis Lc ′ and the deflection surface 52 ′ It swings around the swing axis Lc ′.
  • this resonance type deflection element 50 ′ as shown in FIG. 12, when the frequency of the drive signal Sig1 is made higher than the resonance frequency fs, the oscillation amplitude (the deflection angle) of the deflection surface 52 is suddenly reduced. Even if the frequency of the drive signal Sig1 is lowered from the resonance frequency fs, the swing amplitude (swing angle) of the deflecting surface 52 does not rapidly decrease.
  • the drive control unit 10 drives the resonance type deflection element 50 ′ with a drive signal Sig 1 having a frequency fo lower than the resonance frequency fs by a predetermined frequency ⁇ f. In this way, even when the frequency of the drive signal Sig1 is not the same as the resonance frequency fs, the swing amplitude of the deflection surface 52 can be increased with a small drive signal Sig1, thereby saving power. be able to.
  • the image display device is an optical scanning image display device, which emits laser light intensity-modulated in accordance with an image signal from a laser, scans the laser light in a two-dimensional direction by a scanning unit, and projects it. The image is projected onto the target and displayed.
  • a retinal scanning type image display device hereinafter referred to as RSD
  • RSD retinal scanning type image display device
  • the RSD 100 is based on an image signal S input from an external input terminal (not shown), and R (red) drive signals 120r and G (green) drive signals that are elements for forming an image.
  • a control unit 110 that generates 120 g, B (blue) drive signal 120 b in units of pixels is provided. Further, the control unit 110 outputs a high-speed driving signal 111 used in the high-speed scanning unit 150 and a low-speed driving signal 112 used in the low-speed scanning unit 160, respectively.
  • the R laser driver 126, the G laser driver 127, and the B laser driver 128 are based on the R drive signal 120r, the G drive signal 120g, and the B drive signal 120b that are output from the control unit 110, respectively.
  • B are supplied to the B laser 125, respectively.
  • Each laser 123, 124, 125 emits laser light whose intensity is modulated in accordance with the drive current supplied from each laser driver 126, 127, 128.
  • the R (red) laser light Lr, G (green) laser light Lg, and B (blue) laser light Lb emitted from the lasers 123, 124, and 125 were collimated by collimating optical systems 131, 132, and 133, respectively.
  • the light enters the dichroic mirrors 134, 135, and 136. Thereafter, the laser beams Lr, Lg, and Lb of the three primary colors are wavelength-selectively reflected and transmitted by these dichroic mirrors 134, 135, and 136, reach the coupling optical system 137, and are combined to the optical fiber cable 140. Emitted.
  • the laser light emitted through the optical fiber cable 140 is collimated by the collimating optical system 141 and is incident on the high-speed scanning unit 150.
  • the high-speed scanning unit 150 includes a resonance-type deflection element 151 having a deflection surface (reflection mirror) 152 for scanning a laser beam in the horizontal direction.
  • the high-speed scanning driving circuit 153 uses the resonance type deflection element 151 based on the high-speed drive signal 111.
  • the deflecting element 151 is driven, and the laser beam is deflected and scanned by the deflecting surface 152.
  • a first relay optical system 155 is provided between the high speed scanning unit 150 and the low speed scanning unit 160, and the laser beam operated by the high speed scanning unit 150 is incident on the low speed scanning unit 160.
  • the low-speed scanning unit 160 includes a non-resonant deflecting element 161 having a deflection surface (reflection mirror) 162 for scanning the laser beam in the vertical direction, and the low-speed scanning driving circuit 163 is based on the low-speed driving signal 112.
  • the non-resonance type deflection element 161 is driven.
  • the low-speed scanning unit 160 scans a laser beam for forming an image in a vertical direction from the first scanning line toward the last scanning line for each frame of the image to be displayed.
  • the “scanning line” means one scanning on one side in the horizontal direction by the high-speed scanning unit 150.
  • the laser beam scanned by the non-resonant deflection element 161 is half-positioned in front of the eye 201 through the second relay optical system 170 in which two lenses 170a and 170b having positive refractive power are arranged in series.
  • the light is reflected by the mirror 180 and enters the user's pupil 201a.
  • an image corresponding to the image signal S is projected on the retina 201b, and the user recognizes the laser light incident on the pupil 201a as an image.
  • the half mirror 180 transmits the external light La so as to enter the user's pupil 201a, so that the user can visually recognize an image obtained by superimposing an image based on the laser light on the external scene based on the external light La. it can.
  • the control unit 110 operates with a circuit configuration similar to that of the drive control unit 10 of the optical scanning device 1, and the high-speed scanning drive circuit 153 is similar to the DC voltage superimposing unit 40. Operates with a circuit configuration. That is, in the RSD 100, the frequency of the high-speed drive signal 111 for driving the resonance type deflection element 151 is changed, and the oscillation amplitude of the deflection surface 152 is detected based on the BD signal output from the BD sensor 154. The resonance frequency fs inherent to 151 is determined.
  • the RSD 100 drives the resonant deflection element 151 with the high-speed drive signal 111 having a frequency shifted from the resonance frequency fs by a predetermined frequency ⁇ f, and then changes the amplitude of the high-speed drive signal 111 to change the swing amplitude of the deflection surface 152. Is set to a predetermined value.
  • the RSD 100 is configured in this manner, it is possible to suppress the swing amplitude of the deflecting surface 152 from rapidly decreasing due to a jump phenomenon, and the resonance frequency of the resonant deflection element 151 due to a change in ambient temperature or the like. Even when fs changes, the deflection surface 152 can be maintained at a constant oscillation amplitude.
  • the optical scanning device 1 includes deflection surfaces 52 and 52 ′ for deflecting an incident light beam, and resonance in which the deflection surfaces 52 and 52 swing around the swing axes Lc and Lc ′ due to resonance. It has the type
  • drive control unit 10 drive means
  • the drive control unit 10 drives the resonance type deflection elements 50 and 50 ′ with the drive signal Sig1 having a frequency fo shifted from the resonance frequency fs by a predetermined frequency ⁇ f, and then changes the amplitude of the drive signal Sig1 to change the deflection surface.
  • the swing amplitude of 52 and 52 ′ is set to a predetermined value. Accordingly, it is possible to prevent the swing amplitude of the deflection surface 52 from rapidly decreasing due to the jump phenomenon, and even when the resonance frequency fs of the resonance type deflection element 50 is changed due to a change in the ambient temperature or the like, the deflection is also suppressed.
  • the surface 52 can be maintained at a constant oscillation amplitude.
  • the resonant deflection element 50 is a MEMS in which a region including the deflection surface 52 is formed on a metal substrate.
  • the drive control unit 10 drives the drive signal having a frequency fo that is higher than the resonance frequency fs by a predetermined frequency ⁇ f. Since the swing amplitude of the deflecting surface 52 is set to a predetermined value after the resonant deflection element 50 is driven by Sig1, even if the frequency of the drive signal Sig1 is not the same as the resonance frequency fs, a small drive signal Sig1 is used. The swing amplitude of the deflection surface 52 can be increased, and power saving can be achieved.
  • the resonance type deflection element 50 ′ is a MEMS in which a region including the deflection surface 52 ′ is formed on a silicon substrate, and the drive control unit 10 drives the drive signal having a frequency fs lower than the resonance frequency fs by a predetermined frequency ⁇ f. Since the oscillation amplitude of the deflecting surface 52 ′ is set to a predetermined value after driving the resonant deflection element 50 ′ with Sig1, even if the frequency of the drive signal Sig1 is not the same as the resonance frequency fs, a small drive signal With Sig1, the swing amplitude of the deflection surface 52 ′ can be increased, and power saving can be achieved.
  • the temperature detecting unit 80 that detects the temperature of the resonant deflection elements 50, 50 ′ or the surrounding thereof is provided and the predetermined frequency ⁇ f is a frequency based on the temperature detected by the temperature detecting unit 80, the ambient temperature Even when the resonance frequency fs of the resonance type deflection elements 50, 50 ′ changes due to such changes, the deflection surfaces 52, 52 ′ can be more stably maintained at a constant oscillation amplitude.

Abstract

Provided is an optical scanning device capable of maintaining a deflection surface at a constant oscillation amplitude even when the resonance frequency of a resonance-type deflection element is altered by variations in ambient temperature etc., and also provided is an image display device provided with the optical scanning device. A drive control unit (10) is provided which changes the amplitude of a drive signal (Sig1) and sets the oscillation amplitude of a deflection surface (52) to a prescribed value after the frequency of the drive signal (Sig1) which drives a resonance-type deflection element (50) is changed, the resonance amplitude of the deflection surface (52) is detected, the resonance frequency specific to the resonance-type deflection element (50) is determined, and the resonance-type deflection element (50) is driven by the drive signal (Sig1) having a frequency that is offset from the resonance frequency by a prescribed frequency.

Description

光走査装置及びそれを備えた画像表示装置Optical scanning device and image display device having the same
　本発明は、光走査装置及びそれを備えた画像表示装置に関し、さらに詳細には、入射する光束を偏向する偏向面を有し、共振により偏向面が軸周りに揺動する共振型偏向素子により光束を走査する光走査装置及びそれを備えた画像表示装置に関する。 The present invention relates to an optical scanning device and an image display device including the same, and more specifically, by a resonance type deflection element having a deflection surface for deflecting an incident light beam and swinging around the axis by resonance. The present invention relates to an optical scanning device that scans a light beam and an image display device including the same.
　従来より、画像信号に応じた強度の光束を１次元方向又は２次元方向に走査する光走査装置が知られている。このような光走査装置は、画像信号に応じた強度の光束を２次元方向に走査して、ユーザの少なくとも一方の網膜上に投影することにより画像を表示する網膜走査型画像表示装置や、画像信号に応じた強度の光束を２次元方向に走査してスクリーン上に画像を表示するスクリーン走査型画像表示装置などの画像表示装置に用いられている。 2. Description of the Related Art Conventionally, an optical scanning device that scans a light beam having an intensity corresponding to an image signal in a one-dimensional direction or a two-dimensional direction is known. Such an optical scanning device scans a light beam having an intensity corresponding to an image signal in a two-dimensional direction and projects it onto at least one retina of a user, and displays an image, It is used in an image display device such as a screen scanning type image display device that displays an image on a screen by scanning a light beam having an intensity corresponding to a signal in a two-dimensional direction.
　例えば、下記特許文献１に記載の画像表示装置では、相対的に高速に反射ミラーを揺動可能な共振型偏向素子と、相対的に低速に反射ミラーを揺動可能な非共振型偏向素子とにより光束を走査して画像を表示する。すなわち、画像信号に応じた強度で光源から出射された光束を、共振型偏向素子の反射ミラーを共振させて第１方向に走査し、さらに非共振型偏向素子の反射ミラーを鋸歯波状、三角波状又は台形波状に駆動させて光束を第２方向へ走査して、画像を表示する。なお、第１方向は例えば水平方向であり、第２方向は例えば垂直方向である。 For example, in the image display device described in Patent Document 1 below, a resonant deflection element that can swing the reflection mirror at a relatively high speed, and a non-resonance deflection element that can swing the reflection mirror at a relatively low speed, By scanning the luminous flux, an image is displayed. That is, the light beam emitted from the light source with the intensity corresponding to the image signal is scanned in the first direction by resonating the reflection mirror of the resonance type deflection element, and the reflection mirror of the non-resonance type deflection element is sawtooth wave or triangular wave Or it drives by trapezoid wave shape and scans a light beam to a 2nd direction, and displays an image. The first direction is, for example, the horizontal direction, and the second direction is, for example, the vertical direction.
特開２００６－２７６３９６号公報JP 2006-276396 A
　共振型偏向素子を有する光走査装置では、共振型偏向素子の偏向面を共振型偏向素子固有の共振周波数で揺動させることにより、低消費電力かつ高速に偏向面を揺動させることができる。 In an optical scanning device having a resonance type deflection element, the deflection surface of the resonance type deflection element is oscillated at a resonance frequency unique to the resonance type deflection element, whereby the deflection surface can be oscillated at low power consumption and at high speed.
　しかし、共振型偏向素子固有の共振周波数は、共振型偏向素子の個体差によって異なるため、共振型偏向素子毎に共振周波数を検出して、共振型偏向素子を駆動させる必要がある。 However, since the resonance frequency unique to the resonance type deflection element differs depending on the individual difference of the resonance type deflection element, it is necessary to detect the resonance frequency for each resonance type deflection element and drive the resonance type deflection element.
　しかし、共振型偏向素子は、周波数がずれたときに急激に偏向面の揺動振幅が変化する跳躍特性を有している。そのため、周囲温度等の変化により共振型偏向素子の共振周波数が変化した場合には、共振型偏向素子を駆動する駆動信号の周波数も追従して変更しなければ、偏向面の揺動振幅（振れ角）が急激に小さくなる恐れがある。このとき、駆動信号の周波数を変更することなく、偏向面を一定の揺動振幅に維持させようとして駆動信号の電圧を上昇させると、共振ポイントからずれたところで偏向面を揺動させることになるため共振型偏向素子の消費電力が増大してしまう。しかも、共振ポイントからずれたところで偏向面を揺動させた場合、大きな揺動振幅を得ることができない。 However, the resonance type deflection element has a jumping characteristic in which the oscillation amplitude of the deflection surface changes suddenly when the frequency is shifted. Therefore, if the resonant frequency of the resonant deflection element changes due to changes in the ambient temperature or the like, the oscillation amplitude (swing) of the deflection surface must be changed without changing the frequency of the drive signal for driving the resonant deflection element. There is a risk that the angle will be rapidly reduced. At this time, if the voltage of the drive signal is increased to maintain the deflection surface at a constant oscillation amplitude without changing the frequency of the drive signal, the deflection surface is oscillated at a position deviating from the resonance point. Therefore, the power consumption of the resonance type deflection element increases. Moreover, when the deflection surface is swung at a position deviating from the resonance point, a large swing amplitude cannot be obtained.
　本発明は、周囲温度等の変化により共振型偏向素子の共振周波数が変化した場合においても、偏向面を一定の揺動振幅に維持することができる光走査装置及びそれを備えた画像表示装置を提供することを目的とする。 The present invention provides an optical scanning device capable of maintaining a deflection surface at a constant oscillation amplitude even when the resonance frequency of a resonance type deflection element changes due to a change in ambient temperature or the like, and an image display device including the same. The purpose is to provide.
　上記目的を達成するために、本発明の光走査装置では、入射する光束を偏向する偏向面を有し、共振により前記偏向面が軸周りに揺動する共振型偏向素子と、前記共振型偏向素子を駆動する駆動信号の周波数を変化させ、前記偏向面の揺動振幅を検出して、前記共振型偏向素子固有の共振周波数を判定し、この共振周波数から所定周波数だけずれた周波数の前記駆動信号で前記共振型偏向素子を駆動した後、前記駆動信号の振幅を変更して前記偏向面の揺動振幅を所定値にする駆動手段と、を備えている。 In order to achieve the above object, in the optical scanning device of the present invention, a resonance type deflection element having a deflection surface for deflecting an incident light beam, the deflection surface oscillating around an axis by resonance, and the resonance type deflection device. The frequency of the drive signal for driving the element is changed, the oscillation amplitude of the deflection surface is detected, the resonance frequency unique to the resonance-type deflection element is determined, and the drive at a frequency shifted from the resonance frequency by a predetermined frequency Drive means for changing the amplitude of the drive signal to drive the swing amplitude of the deflection surface to a predetermined value after driving the resonant deflection element with a signal.
　また、前記光走査装置において、前記共振型偏向素子は、メタル基板上に前記偏向面を含む領域が形成されたＭＥＭＳであり、前記駆動手段は、前記共振周波数から所定周波数だけ高い周波数の前記駆動信号で前記共振型偏向素子を駆動した後、前記偏向面の揺動振幅を所定値にしてもよい。 Further, in the optical scanning device, the resonant deflection element is a MEMS in which a region including the deflection surface is formed on a metal substrate, and the driving means has the drive having a frequency higher than the resonance frequency by a predetermined frequency. After the resonance type deflection element is driven by a signal, the swing amplitude of the deflection surface may be set to a predetermined value.
　また、前記光走査装置において、前記共振型偏向素子は、シリコン基板上に前記偏向面を含む領域が形成されたＭＥＭＳであり、前記駆動手段は、前記共振周波数から所定周波数だけ低い周波数の前記駆動信号で前記共振型偏向素子を駆動した後、前記偏向面の揺動振幅を所定値にしてもよい。 Further, in the optical scanning device, the resonant deflection element is a MEMS in which a region including the deflection surface is formed on a silicon substrate, and the drive means has the drive having a frequency lower than the resonance frequency by a predetermined frequency. After the resonance type deflection element is driven by a signal, the swing amplitude of the deflection surface may be set to a predetermined value.
　また、前記光走査装置において、前記共振型偏向素子又はその周囲の温度を検出する温度検出手段を備え、前記所定周波数は、前記温度検出手段によって検出された温度に基づいた周波数としてもよい。 The optical scanning device may further include a temperature detection unit that detects a temperature of the resonant deflection element or its surroundings, and the predetermined frequency may be a frequency based on a temperature detected by the temperature detection unit.
　また、前記光走査装置を備え、画像信号に応じた強度の光束を前記光走査装置により走査し、ユーザの少なくとも一方の眼に向けて出射させることで、画像を表示する網膜走査型の画像表示装置としてもよい。 A retinal scanning type image display that includes the optical scanning device and displays an image by scanning a light beam having an intensity corresponding to an image signal with the optical scanning device and emitting the light beam toward at least one eye of a user. It is good also as an apparatus.
　本発明によれば、共振周波数から所定周波数だけずれた周波数の駆動信号で共振型偏向素子を駆動した後、駆動信号の振幅レベルを変更して偏向面の揺動振幅を所定値にするので、周囲温度等の変化により共振型偏向素子の共振周波数が変化した場合においても、偏向面を一定の揺動振幅に維持することができる。 According to the present invention, after driving the resonant deflection element with a drive signal having a frequency shifted from the resonance frequency by a predetermined frequency, the amplitude level of the drive signal is changed to set the swing amplitude of the deflection surface to a predetermined value. Even when the resonance frequency of the resonant deflection element changes due to a change in ambient temperature or the like, the deflection surface can be maintained at a constant oscillation amplitude.
本発明の一実施形態に係る光走査装置の構成を示す図である。It is a figure which shows the structure of the optical scanning device which concerns on one Embodiment of this invention. 共振型偏向素子の構成を示す図である。It is a figure which shows the structure of a resonance-type deflection | deviation element. 共振型偏向素子の特性を示す図である。It is a figure which shows the characteristic of a resonance type deflection | deviation element. 共振型偏向素子の特性を示す図である。It is a figure which shows the characteristic of a resonance type deflection | deviation element. 共振型偏向素子の特性を示す図である。It is a figure which shows the characteristic of a resonance type deflection | deviation element. 共振型偏向素子の特性を示す図である。It is a figure which shows the characteristic of a resonance type deflection | deviation element. 共振型偏向素子の特性を示す図である。It is a figure which shows the characteristic of a resonance type deflection | deviation element. 偏向面の揺動振幅（振れ角）と偏向面との位相差との関係を示す図である。It is a figure which shows the relationship between the rocking | fluctuation amplitude (deflection angle) of a deflection surface, and the phase difference of a deflection surface. 駆動制御部の処理の流れを示す図である。It is a figure which shows the flow of a process of a drive control part. 本発明の一実施形態に係る他の光走査装置の構成を示す図である。It is a figure which shows the structure of the other optical scanning device which concerns on one Embodiment of this invention. 別の偏向素子の構成を示す図である。It is a figure which shows the structure of another deflection | deviation element. 図１１に示す偏向素子の特性を示す図である。It is a figure which shows the characteristic of the deflection | deviation element shown in FIG. 本発明の一実施形態に係る画像表示装置の構成を示す図である。It is a figure which shows the structure of the image display apparatus which concerns on one Embodiment of this invention.
　以下、本発明の一実施形態に係る光走査装置及びそれを備えた画像表示装置について図面を参照して具体的に説明する。 Hereinafter, an optical scanning device and an image display device including the same according to an embodiment of the present invention will be specifically described with reference to the drawings.
　［１．光走査装置の構成］
　本実施形態に係る光走査装置１は、駆動制御部１０、直流電圧重畳部４０、共振型偏向素子５０、光源６０、ＢＤセンサ７０を有している。 [1. Configuration of optical scanning device]
The optical scanning device 1 according to this embodiment includes a drive control unit 10, a DC voltage superimposing unit 40, a resonant deflection element 50, a light source 60, and a BD sensor 70.
　駆動制御部１０は、共振型偏向素子５０を駆動する駆動信号Ｓｉｇ１を生成する駆動手段であり、周波数決定部１１と、振幅決定部１２と、駆動信号生成部１３とを有している。駆動信号生成部１３は、周波数決定部１１及び振幅決定部１２により決定された周波数ｆｏ及び振幅Ｖｐの駆動信号Ｓｉｇ１を生成して出力する。 The drive control unit 10 is a drive unit that generates a drive signal Sig1 that drives the resonant deflection element 50, and includes a frequency determination unit 11, an amplitude determination unit 12, and a drive signal generation unit 13. The drive signal generation unit 13 generates and outputs a drive signal Sig1 having the frequency fo and the amplitude Vp determined by the frequency determination unit 11 and the amplitude determination unit 12.
　直流電圧重畳部４０は、直流電圧印加部４１と、信号重畳回路４２とを有している。そして、駆動制御部１０から出力された駆動信号Ｓｉｇ１に、信号重畳回路４２により、直流電圧印加部４１で生成された直流電圧が重畳されて、共振型偏向素子５０の駆動部５１に印加される。共振型偏向素子５０の偏向面５２は、直流電圧に重畳された駆動信号Ｓｉｇ１に基づいて揺動する。なお、駆動部５１は、例えば圧電素子などにより構成される。 The DC voltage superimposing unit 40 includes a DC voltage applying unit 41 and a signal superimposing circuit 42. Then, the direct current voltage generated by the direct current voltage application unit 41 is superimposed on the drive signal Sig 1 output from the drive control unit 10 by the signal superimposing circuit 42 and applied to the drive unit 51 of the resonant deflection element 50. . The deflection surface 52 of the resonant deflection element 50 swings based on the drive signal Sig1 superimposed on the DC voltage. In addition, the drive part 51 is comprised by the piezoelectric element etc., for example.
　ここで、共振型偏向素子５０は、薄板状のメタル基板上に形成されたＭＥＭＳであり、例えば、図２に示すような形状を有している。また、メタル基板として、アルミ基板、銅基板、鉄基板などがある。図２に示す例では、共振型偏向素子５０は、駆動部５１と、偏向面（反射ミラー）５２と、枠体５３と、梁部５４，５４とを有して構成されている。そして、駆動部５１に直流電圧に重畳された駆動信号Ｓｉｇ１が印加され、この駆動部５１の変位により、駆動信号Ｓｉｇ１に応じた周波数で、枠体５３と梁部５４，５４と偏向面５２とが振動し、揺動軸Ｌｃを中心として、偏向面５２が軸周りに揺動する。尚、以下においては、偏向面５２の揺動振幅とは、偏向面５２の回転角度範囲であり、偏向面５２の振れ角である。 Here, the resonant deflection element 50 is a MEMS formed on a thin plate-like metal substrate, and has, for example, a shape as shown in FIG. Examples of the metal substrate include an aluminum substrate, a copper substrate, and an iron substrate. In the example shown in FIG. 2, the resonant deflection element 50 includes a drive unit 51, a deflection surface (reflection mirror) 52, a frame body 53, and beam portions 54 and 54. Then, the drive signal Sig1 superimposed on the DC voltage is applied to the drive unit 51. Due to the displacement of the drive unit 51, the frame body 53, the beam portions 54 and 54, the deflection surface 52, and the frequency at the frequency according to the drive signal Sig1. Oscillates, and the deflection surface 52 swings about the axis about the swing axis Lc. In the following description, the swing amplitude of the deflection surface 52 is a rotation angle range of the deflection surface 52 and is a deflection angle of the deflection surface 52.
　図３に、ある温度で所定振幅の駆動信号Ｓｉｇ１をその周波数を変化させながら入力したときの共振型偏向素子５０の偏向面５２の揺動振幅特性を示す。同図に示すように、共振周波数ｆｓから周波数が少しずれたところに急激に偏向面５２の揺動振幅が変化する跳躍現象が発生する箇所が存在する。そのため、周囲温度等の変化により共振型偏向素子５０の共振周波数ｆｓが変化した場合には、共振型偏向素子５０を駆動する駆動信号Ｓｉｇ１の周波数も追従して変更しなければ、偏向面５２の揺動振幅が急激に小さくなる恐れがある。 FIG. 3 shows the oscillation amplitude characteristics of the deflection surface 52 of the resonant deflection element 50 when a drive signal Sig1 having a predetermined amplitude is inputted at a certain temperature while changing its frequency. As shown in the figure, there is a location where a jump phenomenon occurs in which the oscillation amplitude of the deflecting surface 52 suddenly changes when the frequency slightly deviates from the resonance frequency fs. Therefore, when the resonance frequency fs of the resonant deflection element 50 changes due to a change in the ambient temperature or the like, the frequency of the drive signal Sig1 for driving the resonant deflection element 50 must be changed following the change. There is a possibility that the swing amplitude is rapidly reduced.
　しかも、メタルで構成された共振型偏向素子５０では、図４に示すように、駆動信号Ｓｉｇ１の周波数を上昇させていったときの振幅特性と、駆動信号Ｓｉｇ１の周波数を下降させていったときの振幅特性が異なっている。そのため、偏向面５２の揺動振幅が急激に小さくなった後に、駆動信号Ｓｉｇ１の周波数と共振型偏向素子５０の共振周波数ｆｓに合わせるのに時間がかかってしまう場合がある。なお、図４においては、駆動信号Ｓｉｇ１の周波数を下降させながら入力したときの特性を実線で示し、駆動信号Ｓｉｇ１の周波数を上昇させながら入力したときの特性を波線で示す。 Moreover, in the resonant deflection element 50 made of metal, as shown in FIG. 4, when the frequency of the drive signal Sig1 is increased, and when the frequency of the drive signal Sig1 is decreased, as shown in FIG. Have different amplitude characteristics. For this reason, it may take time to match the frequency of the drive signal Sig1 and the resonance frequency fs of the resonance type deflection element 50 after the swing amplitude of the deflection surface 52 is rapidly reduced. In FIG. 4, the characteristics when the drive signal Sig1 is input while decreasing the frequency are indicated by solid lines, and the characteristics when the drive signal Sig1 is input while increasing the frequency are indicated by wavy lines.
　そこで、本実施形態に係る光走査装置１では、所定振幅の駆動信号Ｓｉｇ１の周波数を変化させながら共振型偏向素子５０固有の共振周波数ｆｓを判定し、図５に示すように、共振周波数ｆｓから所定周波数Δｆだけ高い周波数ｆｏの駆動信号Ｓｉｇ１で共振型偏向素子５０を駆動するようにしている。 Therefore, in the optical scanning device 1 according to the present embodiment, the resonance frequency fs unique to the resonance type deflection element 50 is determined while changing the frequency of the drive signal Sig1 having a predetermined amplitude, and from the resonance frequency fs as shown in FIG. The resonant deflection element 50 is driven by a drive signal Sig1 having a frequency fo that is higher by a predetermined frequency Δf.
　このようにすることで、図６に示すように、温度変化等により共振型偏向素子５０の特性が、実線で示す特性から波線で示す特性となったときでも、偏向面５２の揺動振幅が小さくなることを抑えることができる。すなわち、駆動信号Ｓｉｇ１の周波数ｆｏを、共振型偏向素子５０固有の共振周波数ｆｓから所定周波数Δｆだけ高い周波数とすることで、温度変化などによる特性変化に対してマージンをとることができる。 By doing so, as shown in FIG. 6, even when the characteristic of the resonant deflecting element 50 changes from the characteristic indicated by the solid line to the characteristic indicated by the broken line due to a temperature change or the like, the oscillation amplitude of the deflecting surface 52 is increased. It can be suppressed from becoming smaller. That is, by setting the frequency fo of the drive signal Sig1 to a frequency that is higher by a predetermined frequency Δf than the resonance frequency fs inherent to the resonance type deflection element 50, a margin can be taken against a characteristic change due to a temperature change or the like.
　また、共振型偏向素子５０の特性は、駆動信号Ｓｉｇ１の振幅Ｖｐによっても変化する。図７に、共振型偏向素子５０の特性を駆動信号Ｓｉｇ１の振幅Ｖｐ毎（５Ｖ，７Ｖ，１１．５Ｖ，１３Ｖ）に示した図である。同図からわかるように、駆動信号Ｓｉｇ１の振幅Ｖｐによって揺動振幅も異なるが、共振型偏向素子５０の共振周波数ｆｓも異なるものとなる。従って、駆動信号Ｓｉｇ１の周波数を決定した後に、駆動信号Ｓｉｇ１の振幅Ｖｐを変化させると、偏向面５２の揺動振幅が変化する。特に、駆動信号Ｓｉｇ１の振幅Ｖｐを大きく変化させると、偏向面５２の揺動振幅の変化が大きくなり、駆動信号Ｓｉｇ１の周波数が共振周波数ｆｓから外れて偏向面５２の揺動振幅が急激に小さくなる恐れがある。 Further, the characteristics of the resonant deflection element 50 also change depending on the amplitude Vp of the drive signal Sig1. FIG. 7 is a diagram showing the characteristics of the resonant deflection element 50 for each amplitude Vp (5V, 7V, 11.5V, 13V) of the drive signal Sig1. As can be seen from the figure, the oscillation amplitude varies depending on the amplitude Vp of the drive signal Sig1, but the resonance frequency fs of the resonance type deflection element 50 also varies. Therefore, if the amplitude Vp of the drive signal Sig1 is changed after the frequency of the drive signal Sig1 is determined, the swing amplitude of the deflection surface 52 changes. In particular, when the amplitude Vp of the drive signal Sig1 is greatly changed, the change in the swing amplitude of the deflection surface 52 increases, and the frequency of the drive signal Sig1 deviates from the resonance frequency fs, and the swing amplitude of the deflection surface 52 decreases rapidly. There is a fear.
　そこで、本実施形態に係る光走査装置１では、駆動信号Ｓｉｇ１の振幅をある程度大きくしてからその周波数ｆｏを決定し、その後、振幅Ｖｐを変化させるようにしている。このようにすることで、駆動信号Ｓｉｇ１の振幅変化によって、偏向面５２の揺動振幅が急激に小さくなることを抑制することができる。 Therefore, in the optical scanning device 1 according to this embodiment, the amplitude of the drive signal Sig1 is increased to some extent, the frequency fo is determined, and then the amplitude Vp is changed. By doing so, it is possible to suppress the swing amplitude of the deflection surface 52 from rapidly decreasing due to the amplitude change of the drive signal Sig1.
　さらに、本実施形態に係る光走査装置１では、駆動信号Ｓｉｇ１の信号波形と偏向面５２の揺動波形との位相差θｃに基づいて、駆動信号Ｓｉｇ１の周波数を調整することで、さらに精度よく偏向面５２を揺動するようにしている。すなわち、上述のように駆動信号Ｓｉｇ１の周波数ｆｏを決定し、偏向面５２の揺動振幅を所定振幅に調整した後に、位相差θｃが所定範囲Ｚ内（図８参照）から外れたときには、位相差θｃが所定範囲Ｚ内になるように駆動信号Ｓｉｇ１の周波数を調整するようにしている。 Furthermore, in the optical scanning device 1 according to the present embodiment, the frequency of the drive signal Sig1 is adjusted more accurately by adjusting the frequency of the drive signal Sig1 based on the phase difference θc between the signal waveform of the drive signal Sig1 and the oscillation waveform of the deflection surface 52. The deflection surface 52 is swung. That is, after determining the frequency fo of the drive signal Sig1 and adjusting the swing amplitude of the deflection surface 52 to a predetermined amplitude as described above, when the phase difference θc is out of the predetermined range Z (see FIG. 8), The frequency of the drive signal Sig1 is adjusted so that the phase difference θc is within the predetermined range Z.
　また、偏向面５２の揺動振幅を一定に保つために駆動信号Ｓｉｇ１の振幅Ｖｐを変更する場合には、位相差θｃが所定範囲Ｚ内であることを確認してから行うようにしている。すなわち、位相差θｃによる周波数制御を、振幅制御よりも優先して行うようにしている。このようにすることでさらに精度よく偏向面５２を揺動することができる。 Further, when the amplitude Vp of the drive signal Sig1 is changed in order to keep the swinging amplitude of the deflection surface 52 constant, it is performed after confirming that the phase difference θc is within the predetermined range Z. That is, the frequency control based on the phase difference θc is performed with priority over the amplitude control. In this way, the deflection surface 52 can be oscillated with higher accuracy.
　このように光走査装置１が構成されているため、跳躍現象により偏向面５２の揺動振幅が急激に小さくなることを抑制することができ、しかも、光走査装置１の環境変化に合わせた共振型偏向素子５０の駆動を行うことが可能となる。 Since the optical scanning device 1 is configured as described above, it is possible to suppress the swing amplitude of the deflecting surface 52 from rapidly decreasing due to the jump phenomenon, and to resonate in accordance with the environmental change of the optical scanning device 1. The mold deflection element 50 can be driven.
　上述した動作を行うために、周波数決定部１１、振幅決定部１２、駆動信号生成部１３、直流電圧重畳部４０は以下のように構成されている。 In order to perform the above-described operation, the frequency determining unit 11, the amplitude determining unit 12, the drive signal generating unit 13, and the DC voltage superimposing unit 40 are configured as follows.
　周波数決定部１１は、共振型偏向素子５０固有の共振周波数ｆｓを検出し、この共振周波数ｆｓに対して所定周波数Δｆだけ高い周波数を駆動信号Ｓｉｇ１の周波数ｆｏとして決定する。その後、周波数決定部１１は、駆動信号Ｓｉｇ１と共振型偏向素子５０の揺動状態との位相差θｃが所定範囲を超えたとき、駆動信号Ｓｉｇ１の周波数ｆｏを変更して、その位相差θｃが所定範囲Ｚ内になるようにする。 The frequency determination unit 11 detects the resonance frequency fs unique to the resonance type deflection element 50 and determines a frequency higher than the resonance frequency fs by a predetermined frequency Δf as the frequency fo of the drive signal Sig1. Thereafter, when the phase difference θc between the drive signal Sig1 and the oscillation state of the resonant deflection element 50 exceeds a predetermined range, the frequency determination unit 11 changes the frequency fo of the drive signal Sig1, and the phase difference θc is Within a predetermined range Z.
　この周波数決定部１１は、位相差判定部２１と、目標位相差記憶部２２と、位相差比較部２３と、周波数変更制御部２４とを有している。 The frequency determination unit 11 includes a phase difference determination unit 21, a target phase difference storage unit 22, a phase difference comparison unit 23, and a frequency change control unit 24.
　位相差判定部２１は、駆動信号Ｓｉｇ１の信号波形と偏向面５２の揺動波形との位相差θｃを判定する。ＢＤセンサ７０は偏向面５２が所定の傾き角にあるときに光源６０から出射された光束を入射して検出信号（以下、ＢＤ信号という）を出力している。位相差判定部２１は、ＢＤセンサ７０からのＢＤ信号の出力タイミングに基づき、偏向面５２の傾き角の状態を検出し、駆動信号Ｓｉｇ１の波形と偏向面５２の揺動波形との位相差θｃを判定する。なお、位相差判定部２１において、例えば、偏向面５２の傾き角が＋Ｘから－Ｘへ向かうときに傾き角が０になるタイミングと、駆動信号Ｓｉｇ１が正電圧から負電圧に向かうときに電圧が０Ｖとなるタイミングとを検出し、これらのタイミングの関係から、位相差θｃを判定するようにしてもよい。なお、正電圧の駆動信号を駆動部５１に印加したときに、偏向面５２の傾き角が＋Ｘ方向になるものとする。 The phase difference determination unit 21 determines the phase difference θc between the signal waveform of the drive signal Sig1 and the swing waveform of the deflection surface 52. The BD sensor 70 receives a light beam emitted from the light source 60 when the deflecting surface 52 is at a predetermined tilt angle, and outputs a detection signal (hereinafter referred to as a BD signal). The phase difference determination unit 21 detects the tilt angle state of the deflection surface 52 based on the output timing of the BD signal from the BD sensor 70, and the phase difference θc between the waveform of the drive signal Sig1 and the swing waveform of the deflection surface 52. Determine. In the phase difference determination unit 21, for example, when the tilt angle of the deflecting surface 52 goes from + X to -X, the timing when the tilt angle becomes 0 and when the drive signal Sig1 goes from a positive voltage to a negative voltage, It is also possible to detect the timing when it becomes 0 V and determine the phase difference θc from the relationship between these timings. It is assumed that the inclination angle of the deflection surface 52 is in the + X direction when a positive voltage drive signal is applied to the drive unit 51.
　目標位相差記憶部２２は、起動許容できる位相差θｃの範囲である所定範囲Ｚの情報が記憶されている。位相差比較部２３は、位相差判定部２１から位相差θｃを取得すると共に、目標位相差記憶部２２から所定範囲Ｚの情報を取得し、位相差θｃが所定範囲Ｚ内にあるか否かを判定する。 The target phase difference storage unit 22 stores information on a predetermined range Z that is a range of the phase difference θc that can be activated. The phase difference comparison unit 23 acquires the phase difference θc from the phase difference determination unit 21 and also acquires information on the predetermined range Z from the target phase difference storage unit 22, and whether or not the phase difference θc is within the predetermined range Z. Determine.
　周波数変更制御部２４は、位相差θｃが所定範囲Ｚ内にないときに、位相差判定部２１から出力される位相差θｃが所定範囲Ｚの上限値より大きければ、位相差判定部２１から出力される位相差θｃが所定範囲Ｚの下限値より小さくなるまで、駆動信号生成部１３を制御して駆動信号Ｓｉｇ１の周波数を上げてく。その後、周波数変更制御部２４は、位相差判定部２１から出力される位相差θｃが９０［ｄｅｇ］になるまで、駆動信号生成部１３を制御して駆動信号Ｓｉｇ１の周波数を下げていく。位相差判定部２１から出力される位相差θｃが９０［ｄｅｇ］になったときの駆動信号Ｓｉｇ１の周波数が共振周波数ｆｓである。従って、周波数変更制御部２４は、位相差判定部２１から出力される位相差θｃが９０［ｄｅｇ］になったときの駆動信号Ｓｉｇ１の周波数を共振周波数ｆｓとして判定する。 The frequency change control unit 24 outputs the phase difference θc from the phase difference determination unit 21 if the phase difference θc output from the phase difference determination unit 21 is larger than the upper limit value of the predetermined range Z when the phase difference θc is not within the predetermined range Z. The drive signal generation unit 13 is controlled to increase the frequency of the drive signal Sig1 until the phase difference θc is smaller than the lower limit value of the predetermined range Z. Thereafter, the frequency change control unit 24 controls the drive signal generation unit 13 to lower the frequency of the drive signal Sig1 until the phase difference θc output from the phase difference determination unit 21 reaches 90 [deg]. The frequency of the drive signal Sig1 when the phase difference θc output from the phase difference determination unit 21 reaches 90 [deg] is the resonance frequency fs. Therefore, the frequency change control unit 24 determines the frequency of the drive signal Sig1 when the phase difference θc output from the phase difference determination unit 21 is 90 [deg] as the resonance frequency fs.
　また、周波数変更制御部２４は、位相差θｃが所定範囲Ｚ内にないときに、位相差判定部２１から出力される位相差θｃが所定範囲Ｚの下限値より小さければ、位相差判定部２１から出力される位相差θｃが９０［ｄｅｇ］となるまで、駆動信号生成部１３を制御して駆動信号Ｓｉｇ１の周波数を下げていく。そして、周波数変更制御部２４は、位相差判定部２１から出力される位相差θｃが９０［ｄｅｇ］になったときの駆動信号Ｓｉｇ１の周波数を共振周波数ｆｓとして判定する。 In addition, when the phase difference θc is not within the predetermined range Z and the phase difference θc output from the phase difference determination unit 21 is smaller than the lower limit value of the predetermined range Z, the frequency change control unit 24 has the phase difference determination unit 21. The drive signal generator 13 is controlled to decrease the frequency of the drive signal Sig <b> 1 until the phase difference θc output from is reduced to 90 [deg]. Then, the frequency change control unit 24 determines the frequency of the drive signal Sig1 when the phase difference θc output from the phase difference determination unit 21 is 90 [deg] as the resonance frequency fs.
　このように、周波数変更制御部２４は、位相差θｃが所定範囲Ｚ内にないとき、駆動信号Ｓｉｇ１の周波数を増減させて共振周波数ｆｓを判定するようにしている。そして、周波数変更制御部２４は、駆動信号生成部１３を制御して、共振周波数ｆｓよりも所定周波数Δｆだけ高い周波数ｆｏの駆動信号Ｓｉｇ１を駆動信号生成部１３から出力させるようにしている。 Thus, when the phase difference θc is not within the predetermined range Z, the frequency change control unit 24 determines the resonance frequency fs by increasing or decreasing the frequency of the drive signal Sig1. Then, the frequency change control unit 24 controls the drive signal generation unit 13 to output from the drive signal generation unit 13 a drive signal Sig1 having a frequency fo higher than the resonance frequency fs by a predetermined frequency Δf.
　振幅決定部１２は、共振型偏向素子５０の偏向面５２の揺動振幅が目標とする揺動振幅となるように、駆動信号生成部１３から出力される駆動信号Ｓｉｇ１の振幅Ｖｐを制御するものであり、位相差θｃが所定範囲Ｚ内となったときに動作する。 The amplitude determination unit 12 controls the amplitude Vp of the drive signal Sig1 output from the drive signal generation unit 13 so that the swing amplitude of the deflection surface 52 of the resonant deflection element 50 becomes the target swing amplitude. And operates when the phase difference θc falls within the predetermined range Z.
　振幅決定部１２は、振幅制御実行切換部３１と、振幅判定部３２と、目標振幅記憶部３３と、振幅比較部３４と、振幅変更制御部３５とを有している。 The amplitude determination unit 12 includes an amplitude control execution switching unit 31, an amplitude determination unit 32, a target amplitude storage unit 33, an amplitude comparison unit 34, and an amplitude change control unit 35.
　振幅制御実行切換部３１は、位相差比較部２３からの出力に基づき、振幅判定部３２の動作を制御する。すなわち、振幅制御実行切換部３１は、位相差θｃが所定範囲Ｚ内にあるときに出力される信号を位相差比較部２３から受信すると、振幅判定部３２を非動作状態にし、位相差θｃが所定範囲Ｚ内にないときに出力される信号を位相差比較部２３から受信すると、振幅判定部３２を動作状態にする。 The amplitude control execution switching unit 31 controls the operation of the amplitude determination unit 32 based on the output from the phase difference comparison unit 23. That is, when the amplitude control execution switching unit 31 receives a signal output when the phase difference θc is within the predetermined range Z from the phase difference comparison unit 23, the amplitude control execution switching unit 31 sets the amplitude determination unit 32 to the non-operation state, and the phase difference θc is When the signal output when it is not within the predetermined range Z is received from the phase difference comparison unit 23, the amplitude determination unit 32 is put into an operating state.
　振幅判定部３２は、振幅制御実行切換部３１から動作状態にされたとき、ＢＤセンサ７０からのＢＤ信号の有無やタイミングに基づき、偏向面５２の揺動振幅を検出する。具体的には、振幅判定部３２は、ＢＤセンサ７０からＢＤ信号が出力されないときには、偏向面５２の揺動振幅が所定範囲以下であると判断する。また、ＢＤセンサ７０からＢＤ信号が出力されているとき、ＢＤセンサ７０から出力されるＢＤ信号の間隔に基づき、偏向面５２の揺動振幅を判断する。 The amplitude determination unit 32 detects the swing amplitude of the deflecting surface 52 based on the presence / absence and timing of the BD signal from the BD sensor 70 when the amplitude control execution switching unit 31 is brought into the operating state. Specifically, when the BD signal is not output from the BD sensor 70, the amplitude determination unit 32 determines that the swinging amplitude of the deflection surface 52 is within a predetermined range. Further, when the BD signal is output from the BD sensor 70, the swing amplitude of the deflection surface 52 is determined based on the interval of the BD signal output from the BD sensor 70.
　目標振幅記憶部３３は、目標とする偏向面５２の揺動振幅（以下、揺動振幅Ｘａとする）の情報を記憶している。振幅比較部３４は、振幅判定部３２から偏向面５２の揺動振幅（以下、揺動振幅Ｘｒとする）の情報を取得すると共に、目標振幅記憶部３３から揺動振幅Ｘａの情報を取得し、揺動振幅Ｘｒと揺動振幅Ｘａとの振幅差（以下、振幅差Ｘｓとする）を求める。なお、振幅比較部３４は、振幅判定部３２が動作していないときには、揺動振幅Ｘｒと揺動振幅Ｘａとの差がない旨の情報（Ｘｓ＝０）を出力する。 The target amplitude storage unit 33 stores information on the swing amplitude (hereinafter referred to as swing amplitude Xa) of the target deflection surface 52. The amplitude comparison unit 34 acquires information on the swing amplitude (hereinafter referred to as swing amplitude Xr) of the deflection surface 52 from the amplitude determination unit 32 and also acquires information on the swing amplitude Xa from the target amplitude storage unit 33. Then, an amplitude difference between the swing amplitude Xr and the swing amplitude Xa (hereinafter referred to as an amplitude difference Xs) is obtained. When the amplitude determination unit 32 is not operating, the amplitude comparison unit 34 outputs information (Xs = 0) indicating that there is no difference between the swing amplitude Xr and the swing amplitude Xa.
　振幅変更制御部３５は、振幅差Ｘｓが所定範囲内となるように、駆動信号生成部１３を制御して駆動信号Ｓｉｇ１の振幅Ｖｐを変更する。なお、振幅変更制御部３５は、振幅差Ｘｓが所定範囲内にあるときには、駆動信号Ｓｉｇ１の振幅Ｖｐの変更は行わない。 The amplitude change control unit 35 controls the drive signal generation unit 13 to change the amplitude Vp of the drive signal Sig1 so that the amplitude difference Xs falls within a predetermined range. The amplitude change control unit 35 does not change the amplitude Vp of the drive signal Sig1 when the amplitude difference Xs is within the predetermined range.
　以上のように構成された光走査装置１における駆動制御部１０の処理を、図９を参照して説明する。なお、図９は、理解を容易にするために簡略化した図としている。 Processing of the drive control unit 10 in the optical scanning device 1 configured as described above will be described with reference to FIG. FIG. 9 is a simplified diagram for easy understanding.
　駆動制御部１０において、共振型偏向素子５０の駆動を開始すると、まず、周波数決定部１１及び振幅決定部１２は所定の周波数及び振幅の駆動信号Ｓｉｇ１が駆動信号生成部１３から出力されるように、駆動信号生成部１３を制御する（ステップＳ１０）。具体的には、周波数決定部１１の周波数変更制御部２４は、駆動信号Ｓｉｇ１が所定の周波数となるように駆動信号生成部１３を制御する。また、振幅決定部１２の振幅変更制御部３５は、駆動信号Ｓｉｇ１が所定の振幅となるように駆動信号生成部１３を制御する。所定の周波数及び振幅とは、例えば、デフォルトとして予め周波数変更制御部２４及び振幅変更制御部３５に設定されている周波数及び振幅である。なお、周波数変更制御部２４及び振幅変更制御部３５が最後に駆動信号Ｓｉｇ１を制御したときの周波数及び振幅を記憶しておき、この周波数及び振幅を所定の周波数及び振幅としてもよい。 In the drive control unit 10, when driving of the resonant deflection element 50 is started, first, the frequency determination unit 11 and the amplitude determination unit 12 output a drive signal Sig 1 having a predetermined frequency and amplitude from the drive signal generation unit 13. Then, the drive signal generation unit 13 is controlled (step S10). Specifically, the frequency change control unit 24 of the frequency determination unit 11 controls the drive signal generation unit 13 so that the drive signal Sig1 has a predetermined frequency. Further, the amplitude change control unit 35 of the amplitude determination unit 12 controls the drive signal generation unit 13 so that the drive signal Sig1 has a predetermined amplitude. The predetermined frequency and amplitude are, for example, the frequency and amplitude set in advance in the frequency change control unit 24 and the amplitude change control unit 35 as defaults. The frequency and amplitude when the frequency change control unit 24 and the amplitude change control unit 35 last controlled the drive signal Sig1 may be stored, and the frequency and amplitude may be set as a predetermined frequency and amplitude.
　次に、周波数決定部１１において、位相差判定部２１と位相差比較部２３とがその動作を開始する。位相差判定部２１は、駆動信号Ｓｉｇ１の信号波形と偏向面５２の揺動波形との位相差θｃを判定する（ステップＳ１１）。この位相差θｃは、位相差比較部２３において、目標位相差記憶部２２から取得した所定範囲Ｚと比較され、位相差θｃが所定範囲Ｚ内にあるか否かを判定される（ステップＳ１２）。 Next, in the frequency determination unit 11, the phase difference determination unit 21 and the phase difference comparison unit 23 start their operations. The phase difference determination unit 21 determines the phase difference θc between the signal waveform of the drive signal Sig1 and the swing waveform of the deflection surface 52 (step S11). The phase difference θc is compared with the predetermined range Z acquired from the target phase difference storage unit 22 in the phase difference comparison unit 23, and it is determined whether or not the phase difference θc is within the predetermined range Z (step S12). .
　位相差θｃが所定範囲Ｚ内にないとき（ステップＳ１２：Ｎｏ）、周波数変更制御部２４は、上述したように、駆動信号Ｓｉｇ１の周波数を増減させて共振周波数ｆｓを検出する。すなわち、周波数変更制御部２４は、駆動信号Ｓｉｇ１の周波数を増減させていき、位相差判定部２１から出力される位相差θｃが９０［ｄｅｇ］になったときの駆動信号Ｓｉｇ１の周波数を共振周波数ｆｓとして判定する。そして、周波数変更制御部２４は、駆動信号生成部１３を制御して、共振周波数ｆｓよりも所定周波数Δｆだけ高い周波数ｆｏの駆動信号Ｓｉｇ１を駆動信号生成部１３から出力させる（ステップＳ１３）。 When the phase difference θc is not within the predetermined range Z (step S12: No), the frequency change control unit 24 detects the resonance frequency fs by increasing or decreasing the frequency of the drive signal Sig1, as described above. That is, the frequency change control unit 24 increases or decreases the frequency of the drive signal Sig1, and the frequency of the drive signal Sig1 when the phase difference θc output from the phase difference determination unit 21 becomes 90 [deg] is determined as the resonance frequency. It is determined as fs. Then, the frequency change control unit 24 controls the drive signal generation unit 13 to output from the drive signal generation unit 13 a drive signal Sig1 having a frequency fo that is higher than the resonance frequency fs by a predetermined frequency Δf (step S13).
　一方、位相差θｃが所定範囲Ｚ内にあるとき（ステップＳ１２：Ｙｅｓ）、周波数変更制御部２４から出力される信号に基づき、振幅制御実行切換部３１は振幅判定部３２を動作状態にし、振幅判定部３２により偏向面５２の揺動振幅を検出させる（ステップＳ１４）。そして、振幅比較部３４は、振幅判定部３２から偏向面５２の揺動振幅Ｘｒと目標とする偏向面５２の揺動振幅Ｘａとを比較し、それらの振幅差Ｘｓを求める（ステップＳ１５）。そして、振幅変更制御部３５は、振幅差Ｘｓが所定範囲外であるときには（ステップＳ１５：Ｎｏ）、振幅差Ｘｓが所定範囲内になるように、駆動信号生成部１３を制御して駆動信号Ｓｉｇ１の振幅を変更する（ステップＳ１６）。 On the other hand, when the phase difference θc is within the predetermined range Z (step S12: Yes), based on the signal output from the frequency change control unit 24, the amplitude control execution switching unit 31 sets the amplitude determination unit 32 in the operating state, and the amplitude The determination unit 32 detects the swing amplitude of the deflection surface 52 (step S14). Then, the amplitude comparison unit 34 compares the swing amplitude Xr of the deflection surface 52 with the swing amplitude Xa of the target deflection surface 52 from the amplitude determination unit 32, and obtains an amplitude difference Xs thereof (step S15). Then, when the amplitude difference Xs is outside the predetermined range (step S15: No), the amplitude change control unit 35 controls the drive signal generation unit 13 so that the amplitude difference Xs is within the predetermined range, thereby driving signal Sig1. Is changed (step S16).
　ステップＳ１３又はステップＳ１６の処理が終了したとき、一方、振幅差Ｘｓが所定範囲内であるときには（ステップＳ１５：Ｙｅｓ）、駆動制御部１０は、外部（例えば、操作部）からの入力に基づき、終了指示があったか否かを判定する（ステップＳ１７）。そして、終了指示がある場合（ステップＳ１７：Ｙｅｓ）には、駆動制御部１０は、共振型偏向素子５０の偏向面５２の揺動を中止して、共振型偏向素子５０の駆動処理を終了する。一方、終了指示がない場合（ステップＳ１７：Ｎｏ）には、処理をステップＳ１１に戻し、ステップＳ１１からの処理を繰り返す。 When the process of step S13 or step S16 is completed, on the other hand, when the amplitude difference Xs is within the predetermined range (step S15: Yes), the drive control unit 10 is based on an input from the outside (for example, the operation unit). It is determined whether or not there is an end instruction (step S17). If there is an end instruction (step S <b> 17: Yes), the drive control unit 10 stops swinging of the deflection surface 52 of the resonant deflection element 50 and ends the driving process of the resonant deflection element 50. . On the other hand, if there is no end instruction (step S17: No), the process returns to step S11, and the processes from step S11 are repeated.
　以上のように、本実施形態に係る光走査装置１では、共振型偏向素子５０を駆動する駆動信号Ｓｉｇ１の周波数を変化させ、偏向面５２の揺動状態を検出して、共振型偏向素子５０固有の共振周波数ｆｓを判定する。そして、光走査装置１は、この共振周波数ｆｓから所定周波数Δｆだけずれた周波数の駆動信号Ｓｉｇ１で共振型偏向素子５０を駆動した後、駆動信号Ｓｉｇ１の振幅Ｖｐを変更して偏向面５２の揺動振幅を所定値にする。 As described above, in the optical scanning device 1 according to the present embodiment, the frequency of the drive signal Sig1 for driving the resonance type deflection element 50 is changed, the oscillation state of the deflection surface 52 is detected, and the resonance type deflection element 50 is detected. The inherent resonance frequency fs is determined. The optical scanning device 1 drives the resonance type deflection element 50 with the drive signal Sig1 having a frequency shifted from the resonance frequency fs by a predetermined frequency Δf, and then changes the amplitude Vp of the drive signal Sig1 to change the vibration of the deflection surface 52. The dynamic amplitude is set to a predetermined value.
　このように光走査装置１が構成されているため、跳躍現象により偏向面５２の揺動振幅が急激に小さくなることを抑制することができ、しかも、周囲温度等の変化により共振型偏向素子５０の共振周波数ｆｓが変化した場合においても、偏向面５２を一定の揺動振幅に維持することができる。 Since the optical scanning device 1 is configured in this way, it is possible to suppress the swing amplitude of the deflecting surface 52 from rapidly decreasing due to the jump phenomenon, and the resonant deflection element 50 due to a change in ambient temperature or the like. Even when the resonance frequency fs changes, the deflection surface 52 can be maintained at a constant oscillation amplitude.
　また、共振型偏向素子５０は、メタル基板上に偏向面５２を含む領域が形成されたＭＥＭＳであり、図３に示すような特性を有している。すなわち、駆動信号Ｓｉｇ１の周波数を共振周波数よりも低くしていくと急激に偏向面５２の揺動振幅（振れ角）が小さくなるが、駆動信号Ｓｉｇ１の周波数を共振周波数から高くしていっても偏向面５２の揺動振幅（振れ角）は急激に小さくならない。そこで、駆動制御部１０は、共振周波数ｆｓから所定周波数Δｆだけ高い周波数ｆｏの駆動信号Ｓｉｇ１で共振型偏向素子５０を駆動するようにしている。このようにすることで、駆動信号Ｓｉｇ１の周波数を共振周波数ｆｓと同一としない場合であっても、小さい駆動信号Ｓｉｇ１で偏向面５２の揺動振幅を大きくとることができ、省電力化を図ることができる。 The resonant deflection element 50 is a MEMS in which a region including a deflection surface 52 is formed on a metal substrate, and has characteristics as shown in FIG. That is, when the frequency of the drive signal Sig1 is made lower than the resonance frequency, the swing amplitude (swing angle) of the deflecting surface 52 is suddenly reduced, but even if the frequency of the drive signal Sig1 is increased from the resonance frequency. The swing amplitude (swing angle) of the deflecting surface 52 does not rapidly decrease. Therefore, the drive control unit 10 drives the resonant deflection element 50 with the drive signal Sig1 having a frequency fo that is higher than the resonant frequency fs by a predetermined frequency Δf. In this way, even when the frequency of the drive signal Sig1 is not the same as the resonance frequency fs, the swing amplitude of the deflection surface 52 can be increased with a small drive signal Sig1, thereby saving power. be able to.
　なお、ＢＤセンサ７０に代えて、共振型偏向素子５０により走査された光束が入射する位置に複数の光電変換素子をアレイ状に設けたラインイメージセンサを設け、ラインイメージセンサの各光電変換素子から出力される信号に基づいて偏向面５２の揺動状態を検出するようにしてもよい。また、共振型偏向素子５０において、枠体５３に新たに圧電素子を設け、偏向面５２の揺動に応じて圧電素子から出力される電気信号に基づき、偏向面５２の揺動状態を検出するようにしてもよい。 Instead of the BD sensor 70, a line image sensor in which a plurality of photoelectric conversion elements are arranged in an array is provided at a position where a light beam scanned by the resonant deflection element 50 is incident. The swinging state of the deflection surface 52 may be detected based on the output signal. Further, in the resonance type deflection element 50, a new piezoelectric element is provided on the frame 53, and the swinging state of the deflection surface 52 is detected based on an electrical signal output from the piezoelectric element in response to the swinging of the deflection surface 52. You may do it.
　また、図１０に示すように、共振型偏向素子５０又はその周囲の温度を検出する温度検出部８０を設け、温度検出部８０による検出結果に応じて、所定周波数Δｆを変更するようにしてもよい。すなわち、周波数変更制御部２４において、温度Ｔと周波数とを関連づけたテーブルを記憶しておき、温度検出部８０によって検出された温度Ｔに関連づけられた周波数を前記テーブルから読み出して、この周波数を所定周波数Δｆとする。このようにすることで、温度に応じて適切に所定周波数Δｆを決めることができ、周囲温度等の変化により共振型偏向素子の共振周波数が変化した場合においても、より安定的に偏向面５２を一定の揺動振幅に維持することができる。なお、温度検出部８０は本発明の温度検出手段に相当する。 In addition, as shown in FIG. 10, a temperature detection unit 80 that detects the temperature of the resonant deflection element 50 or its surroundings is provided, and the predetermined frequency Δf is changed according to the detection result by the temperature detection unit 80. Good. That is, the frequency change control unit 24 stores a table associating the temperature T with the frequency, reads the frequency associated with the temperature T detected by the temperature detection unit 80 from the table, and sets the frequency to a predetermined value. The frequency is Δf. In this way, the predetermined frequency Δf can be appropriately determined according to the temperature, and even when the resonance frequency of the resonance-type deflection element changes due to a change in the ambient temperature or the like, the deflection surface 52 can be made more stable. A constant oscillation amplitude can be maintained. The temperature detecting unit 80 corresponds to the temperature detecting means of the present invention.
　また、共振型偏向素子５０は、メタル基板上に偏向面５２を含む領域が形成されたＭＥＭＳとしたが、シリコン基板上に偏向面を含む領域が形成されたＭＥＭＳを用いるようにしてもよい。例えば、共振型偏向素子５０’を図１１に示すように構成する。同図に示すように、共振型偏向素子５０’は、その偏向面５２’である反射ミラーを四角形状とし、その表面に反射面が形成されている。偏向面５２’は２辺に連結する梁部５４’，５４’により支持され、梁部５４’，５４’は枠体５３’に連結して支持されている。つまり、偏向面５２’は２つの梁部５４’，５４’を介して枠体５３’に揺動可能に支持されている。また、枠体５３’の１つの隅部から梁部５４’に向かって延びる圧電素子からなる駆動部５１’が枠体５３’上に形成されている。これらの偏向面５２’，枠体５３’，梁部５４’，５４’はシリコン基板上に形成されるものである。そして、駆動制御部１０から駆動信号Ｓｉｇ１を直流電圧を重畳して駆動部５１’に入力することで、梁部５４’，５４’の長手方向を揺動軸Ｌｃ’として、偏向面５２’が揺動軸Ｌｃ’周りに揺動する。この共振型偏向素子５０’では、図１２に示すように、駆動信号Ｓｉｇ１の周波数を共振周波数ｆｓよりも高くしていくと急激に偏向面５２の揺動振幅（振れ角）が小さくなるが、駆動信号Ｓｉｇ１の周波数を共振周波数ｆｓから低くしていっても偏向面５２の揺動振幅（振れ角）は急激に小さくならない。そこで、駆動制御部１０は、共振周波数ｆｓから所定周波数Δｆだけ低い周波数ｆｏの駆動信号Ｓｉｇ１で共振型偏向素子５０’を駆動する。このようにすることで、駆動信号Ｓｉｇ１の周波数を共振周波数ｆｓと同一としない場合であっても、小さい駆動信号Ｓｉｇ１で偏向面５２の揺動振幅を大きくとることができ、省電力化を図ることができる。 Further, although the resonance type deflection element 50 is a MEMS in which a region including a deflection surface 52 is formed on a metal substrate, a MEMS in which a region including a deflection surface is formed on a silicon substrate may be used. For example, the resonant deflection element 50 'is configured as shown in FIG. As shown in the figure, the resonance type deflection element 50 'has a reflecting mirror which is a deflection surface 52' having a quadrangular shape, and a reflecting surface is formed on the surface thereof. The deflection surface 52 'is supported by beam portions 54' and 54 'connected to two sides, and the beam portions 54' and 54 'are connected to and supported by a frame 53'. That is, the deflection surface 52 'is supported by the frame 53' via the two beam portions 54 'and 54' so as to be swingable. In addition, a drive unit 51 ′ made of a piezoelectric element extending from one corner of the frame 53 ′ toward the beam 54 ′ is formed on the frame 53 ′. The deflection surface 52 ', the frame 53', and the beam portions 54 'and 54' are formed on the silicon substrate. Then, the drive signal Sig1 is superimposed on the direct current voltage from the drive control unit 10 and input to the drive unit 51 ′, so that the longitudinal direction of the beam portions 54 ′ and 54 ′ becomes the swing axis Lc ′ and the deflection surface 52 ′ It swings around the swing axis Lc ′. In this resonance type deflection element 50 ′, as shown in FIG. 12, when the frequency of the drive signal Sig1 is made higher than the resonance frequency fs, the oscillation amplitude (the deflection angle) of the deflection surface 52 is suddenly reduced. Even if the frequency of the drive signal Sig1 is lowered from the resonance frequency fs, the swing amplitude (swing angle) of the deflecting surface 52 does not rapidly decrease. Therefore, the drive control unit 10 drives the resonance type deflection element 50 ′ with a drive signal Sig 1 having a frequency fo lower than the resonance frequency fs by a predetermined frequency Δf. In this way, even when the frequency of the drive signal Sig1 is not the same as the resonance frequency fs, the swing amplitude of the deflection surface 52 can be increased with a small drive signal Sig1, thereby saving power. be able to.
　［２．画像表示装置］
　次に、上記光走査装置を適用した画像表示装置について説明する。本実施形態に係る画像表示装置は、光走査型画像表示装置であり、画像信号に応じて強度変調したレーザ光をレーザから出射し、このレーザ光を走査部により２次元方向に走査し、投射対象に投射して画像を表示するものである。以下においては、網膜走査型の画像表示装置（以下、ＲＳＤという）を一例に挙げて説明するが、スクリーン投射型の画像表示装置などにも適用することができる。 [2. Image display device]
Next, an image display device to which the optical scanning device is applied will be described. The image display device according to the present embodiment is an optical scanning image display device, which emits laser light intensity-modulated in accordance with an image signal from a laser, scans the laser light in a two-dimensional direction by a scanning unit, and projects it. The image is projected onto the target and displayed. In the following, a retinal scanning type image display device (hereinafter referred to as RSD) will be described as an example, but the present invention can also be applied to a screen projection type image display device.
　本実施形態に係るＲＳＤの電気的構成及び光学的構成について、図１３を参照して説明する。 The electrical configuration and optical configuration of the RSD according to the present embodiment will be described with reference to FIG.
　本実施形態に係るＲＳＤ１００は、外部入力端子（図示せず）から入力された画像信号Ｓに基づいて、画像を形成するための要素となるＲ（赤色）駆動信号１２０ｒ，Ｇ（緑色）駆動信号１２０ｇ，Ｂ（青色）駆動信号１２０ｂを画素単位で生成する制御部１１０を備えている。また、制御部１１０は、高速走査部１５０で使用される高速駆動信号１１１と、低速走査部１６０で使用される低速駆動信号１１２とをそれぞれ出力する。 The RSD 100 according to the present embodiment is based on an image signal S input from an external input terminal (not shown), and R (red) drive signals 120r and G (green) drive signals that are elements for forming an image. A control unit 110 that generates 120 g, B (blue) drive signal 120 b in units of pixels is provided. Further, the control unit 110 outputs a high-speed driving signal 111 used in the high-speed scanning unit 150 and a low-speed driving signal 112 used in the low-speed scanning unit 160, respectively.
　Ｒレーザドライバ１２６，Ｇレーザドライバ１２７，Ｂレーザドライバ１２８は、それぞれ制御部１１０から出力されるＲ駆動信号１２０ｒ，Ｇ駆動信号１２０ｇ，Ｂ駆動信号１２０ｂをもとに、Ｒレーザ１２３，Ｇレーザ１２４，Ｂレーザ１２５へそれぞれ駆動電流を供給する。各レーザ１２３，１２４，１２５は、各レーザドライバ１２６，１２７，１２８から供給される駆動電流に応じて強度変調されたレーザ光を出射する。各レーザ１２３，１２４，１２５から出射したＲ（赤色）レーザ光Ｌｒ，Ｇ（緑色）レーザ光Ｌｇ、Ｂ（青色）レーザ光Ｌｂは、コリメート光学系１３１，１３２，１３３によってそれぞれ平行光化された後に、ダイクロイックミラー１３４，１３５，１３６に入射される。その後、これらのダイクロイックミラー１３４，１３５，１３６により、３原色の各レーザ光Ｌｒ，Ｌｇ，Ｌｂが波長選択的に反射・透過して結合光学系１３７に達し、合波されて光ファイバケーブル１４０へ出射される。 The R laser driver 126, the G laser driver 127, and the B laser driver 128 are based on the R drive signal 120r, the G drive signal 120g, and the B drive signal 120b that are output from the control unit 110, respectively. , B are supplied to the B laser 125, respectively. Each laser 123, 124, 125 emits laser light whose intensity is modulated in accordance with the drive current supplied from each laser driver 126, 127, 128. The R (red) laser light Lr, G (green) laser light Lg, and B (blue) laser light Lb emitted from the lasers 123, 124, and 125 were collimated by collimating optical systems 131, 132, and 133, respectively. Later, the light enters the dichroic mirrors 134, 135, and 136. Thereafter, the laser beams Lr, Lg, and Lb of the three primary colors are wavelength-selectively reflected and transmitted by these dichroic mirrors 134, 135, and 136, reach the coupling optical system 137, and are combined to the optical fiber cable 140. Emitted.
　光ファイバケーブル１４０を介して出射されるレーザ光はコリメート光学系１４１により平行光化され、高速走査部１５０へ入射される。高速走査部１５０は、レーザ光を水平方向に走査するための偏向面（反射ミラー）１５２を有する共振型偏向素子１５１を備えており、高速走査駆動回路１５３により高速駆動信号１１１に基づいて共振型偏向素子１５１を駆動し、偏向面１５２によりレーザ光を偏向して走査する。高速走査部１５０と低速走査部１６０との間には、第１リレー光学系１５５が設けられており、高速走査部１５０により操作されたレーザ光が、低速走査部１６０に入射する。 The laser light emitted through the optical fiber cable 140 is collimated by the collimating optical system 141 and is incident on the high-speed scanning unit 150. The high-speed scanning unit 150 includes a resonance-type deflection element 151 having a deflection surface (reflection mirror) 152 for scanning a laser beam in the horizontal direction. The high-speed scanning driving circuit 153 uses the resonance type deflection element 151 based on the high-speed drive signal 111. The deflecting element 151 is driven, and the laser beam is deflected and scanned by the deflecting surface 152. A first relay optical system 155 is provided between the high speed scanning unit 150 and the low speed scanning unit 160, and the laser beam operated by the high speed scanning unit 150 is incident on the low speed scanning unit 160.
　低速走査部１６０は、レーザ光を垂直方向に走査するための偏向面（反射ミラー）１６２を有する非共振型偏向素子１６１を有しており、低速走査駆動回路１６３により低速駆動信号１１２に基づいて非共振型偏向素子１６１を駆動する。この低速走査部１６０は、表示すべき画像の１フレームごとに、画像を形成するためのレーザ光を最初の走査線から最後の走査線に向かって垂直方向に走査する。ここで「走査線」とは、高速走査部１５０による水平方向への片側１走査を意味する。非共振型偏向素子１６１によって走査されたレーザ光は、正の屈折力を持つ２つのレンズ１７０ａ，１７０ｂが直列配置された第２リレー光学系１７０を介して、眼２０１の前方に位置させたハーフミラー１８０で反射されてユーザの瞳孔２０１ａに入射する。これにより、網膜２０１ｂ上に画像信号Ｓに応じた画像が投影され、ユーザは瞳孔２０１ａに入射するレーザ光を画像として認識する。また、ハーフミラー１８０は外光Ｌａを透過してユーザの瞳孔２０１ａに入射させるようにしており、これによりユーザは外光Ｌａに基づく外景にレーザ光に基づく画像を重ねた画像を視認することができる。 The low-speed scanning unit 160 includes a non-resonant deflecting element 161 having a deflection surface (reflection mirror) 162 for scanning the laser beam in the vertical direction, and the low-speed scanning driving circuit 163 is based on the low-speed driving signal 112. The non-resonance type deflection element 161 is driven. The low-speed scanning unit 160 scans a laser beam for forming an image in a vertical direction from the first scanning line toward the last scanning line for each frame of the image to be displayed. Here, the “scanning line” means one scanning on one side in the horizontal direction by the high-speed scanning unit 150. The laser beam scanned by the non-resonant deflection element 161 is half-positioned in front of the eye 201 through the second relay optical system 170 in which two lenses 170a and 170b having positive refractive power are arranged in series. The light is reflected by the mirror 180 and enters the user's pupil 201a. As a result, an image corresponding to the image signal S is projected on the retina 201b, and the user recognizes the laser light incident on the pupil 201a as an image. Further, the half mirror 180 transmits the external light La so as to enter the user's pupil 201a, so that the user can visually recognize an image obtained by superimposing an image based on the laser light on the external scene based on the external light La. it can.
　以上のように構成されたＲＳＤ１００では、制御部１１０が上記光走査装置１の駆動制御部１０と同様の回路構成を有して動作し、高速走査駆動回路１５３が直流電圧重畳部４０と同様の回路構成を有して動作する。すなわち、ＲＳＤ１００では、共振型偏向素子１５１を駆動する高速駆動信号１１１の周波数を変化させ、ＢＤセンサ１５４から出力されるＢＤ信号に基き偏向面１５２の揺動振幅を検出して、共振型偏向素子１５１固有の共振周波数ｆｓを判定する。そして、ＲＳＤ１００は、この共振周波数ｆｓから所定周波数Δｆだけずれた周波数の高速駆動信号１１１で共振型偏向素子１５１を駆動した後、高速駆動信号１１１の振幅を変更して偏向面１５２の揺動振幅を所定値にする。 In the RSD 100 configured as described above, the control unit 110 operates with a circuit configuration similar to that of the drive control unit 10 of the optical scanning device 1, and the high-speed scanning drive circuit 153 is similar to the DC voltage superimposing unit 40. Operates with a circuit configuration. That is, in the RSD 100, the frequency of the high-speed drive signal 111 for driving the resonance type deflection element 151 is changed, and the oscillation amplitude of the deflection surface 152 is detected based on the BD signal output from the BD sensor 154. The resonance frequency fs inherent to 151 is determined. The RSD 100 drives the resonant deflection element 151 with the high-speed drive signal 111 having a frequency shifted from the resonance frequency fs by a predetermined frequency Δf, and then changes the amplitude of the high-speed drive signal 111 to change the swing amplitude of the deflection surface 152. Is set to a predetermined value.
　このようにＲＳＤ１００が構成されているため、跳躍現象により偏向面１５２の揺動振幅が急激に小さくなることを抑制することができ、しかも、周囲温度等の変化により共振型偏向素子１５１の共振周波数ｆｓが変化した場合においても、偏向面１５２を一定の揺動振幅に維持することができる。 Since the RSD 100 is configured in this manner, it is possible to suppress the swing amplitude of the deflecting surface 152 from rapidly decreasing due to a jump phenomenon, and the resonance frequency of the resonant deflection element 151 due to a change in ambient temperature or the like. Even when fs changes, the deflection surface 152 can be maintained at a constant oscillation amplitude.
　本発明を、上述してきた実施形態を通して説明したが、本実施形態のＲＳＤ１によれば、以下の効果が期待できる。 Although the present invention has been described through the above-described embodiments, the following effects can be expected according to the RSD 1 of the present embodiment.
　（１）本実施形態の光走査装置１は、入射する光束を偏向する偏向面５２，５２’を有し、共振により偏向面５２，５２が揺動軸Ｌｃ，Ｌｃ’周りに揺動する共振型偏向素子５０，５０’を有している。さらに、光走査装置１は、駆動制御部１０（駆動手段）を備え、この駆動制御部１０により、共振型偏向素子５０，５０’を駆動する駆動信号Ｓｉｇ１の周波数を変化させ、偏向面５２，５２’の揺動振幅を検出して、共振型偏向素子５０，５０’固有の共振周波数を判定する。そして、駆動制御部１０は、この共振周波数ｆｓから所定周波数Δｆだけずれた周波数ｆｏの駆動信号Ｓｉｇ１で共振型偏向素子５０，５０’を駆動した後、駆動信号Ｓｉｇ１の振幅を変更して偏向面５２，５２’の揺動振幅を所定値にする。従って、跳躍現象により偏向面５２の揺動振幅が急激に小さくなることを抑制することができ、しかも、周囲温度等の変化により共振型偏向素子５０の共振周波数ｆｓが変化した場合においても、偏向面５２を一定の揺動振幅に維持することができる。 (1) The optical scanning device 1 according to the present embodiment includes deflection surfaces 52 and 52 ′ for deflecting an incident light beam, and resonance in which the deflection surfaces 52 and 52 swing around the swing axes Lc and Lc ′ due to resonance. It has the type | mold deflection | deviation elements 50 and 50 '. Further, the optical scanning device 1 includes a drive control unit 10 (drive means), and the drive control unit 10 changes the frequency of the drive signal Sig1 for driving the resonance type deflection elements 50 and 50 ′, so that the deflection surface 52, The oscillation amplitude of 52 ′ is detected, and the resonance frequency inherent to the resonance type deflection elements 50, 50 ′ is determined. The drive control unit 10 drives the resonance type deflection elements 50 and 50 ′ with the drive signal Sig1 having a frequency fo shifted from the resonance frequency fs by a predetermined frequency Δf, and then changes the amplitude of the drive signal Sig1 to change the deflection surface. The swing amplitude of 52 and 52 ′ is set to a predetermined value. Accordingly, it is possible to prevent the swing amplitude of the deflection surface 52 from rapidly decreasing due to the jump phenomenon, and even when the resonance frequency fs of the resonance type deflection element 50 is changed due to a change in the ambient temperature or the like, the deflection is also suppressed. The surface 52 can be maintained at a constant oscillation amplitude.
　（２）また、共振型偏向素子５０は、メタル基板上に偏向面５２を含む領域が形成されたＭＥＭＳであり、駆動制御部１０は、共振周波数ｆｓから所定周波数Δｆだけ高い周波数ｆｏの駆動信号Ｓｉｇ１で共振型偏向素子５０を駆動した後、偏向面５２の揺動振幅を所定値にするので、駆動信号Ｓｉｇ１の周波数を共振周波数ｆｓと同一としない場合であっても、小さい駆動信号Ｓｉｇ１で偏向面５２の揺動振幅を大きくとることができ、省電力化を図ることができる。 (2) The resonant deflection element 50 is a MEMS in which a region including the deflection surface 52 is formed on a metal substrate. The drive control unit 10 drives the drive signal having a frequency fo that is higher than the resonance frequency fs by a predetermined frequency Δf. Since the swing amplitude of the deflecting surface 52 is set to a predetermined value after the resonant deflection element 50 is driven by Sig1, even if the frequency of the drive signal Sig1 is not the same as the resonance frequency fs, a small drive signal Sig1 is used. The swing amplitude of the deflection surface 52 can be increased, and power saving can be achieved.
　（３）共振型偏向素子５０’は、シリコン基板上に偏向面５２’を含む領域が形成されたＭＥＭＳであり、駆動制御部１０は、共振周波数ｆｓから所定周波数Δｆだけ低い周波数ｆｓの駆動信号Ｓｉｇ１で共振型偏向素子５０’を駆動した後、偏向面５２’の揺動振幅を所定値にするので、駆動信号Ｓｉｇ１の周波数を共振周波数ｆｓと同一としない場合であっても、小さい駆動信号Ｓｉｇ１で偏向面５２’の揺動振幅を大きくとることができ、省電力化を図ることができる。 (3) The resonance type deflection element 50 ′ is a MEMS in which a region including the deflection surface 52 ′ is formed on a silicon substrate, and the drive control unit 10 drives the drive signal having a frequency fs lower than the resonance frequency fs by a predetermined frequency Δf. Since the oscillation amplitude of the deflecting surface 52 ′ is set to a predetermined value after driving the resonant deflection element 50 ′ with Sig1, even if the frequency of the drive signal Sig1 is not the same as the resonance frequency fs, a small drive signal With Sig1, the swing amplitude of the deflection surface 52 ′ can be increased, and power saving can be achieved.
　（４）共振型偏向素子５０，５０’又はその周囲の温度を検出する温度検出部８０を備え、所定周波数Δｆは、温度検出部８０によって検出された温度に基づいた周波数としているので、周囲温度等の変化により共振型偏向素子５０，５０’の共振周波数ｆｓが変化した場合においても、より安定的に偏向面５２，５２’を一定の揺動振幅に維持することができる。 (4) Since the temperature detecting unit 80 that detects the temperature of the resonant deflection elements 50, 50 ′ or the surrounding thereof is provided and the predetermined frequency Δf is a frequency based on the temperature detected by the temperature detecting unit 80, the ambient temperature Even when the resonance frequency fs of the resonance type deflection elements 50, 50 ′ changes due to such changes, the deflection surfaces 52, 52 ′ can be more stably maintained at a constant oscillation amplitude.
　最後に、上述した各実施の形態の説明は本発明の一例であり、本発明は上述の実施の形態に限定されることはない。このため、上述した各実施の形態以外であっても、本発明に係る技術的思想を逸脱しない範囲であれば、設計等に応じて種々の変更が可能であることは勿論である。 Finally, the description of each embodiment described above is an example of the present invention, and the present invention is not limited to the above-described embodiment. For this reason, it is a matter of course that various modifications can be made in accordance with the design and the like as long as they do not depart from the technical idea according to the present invention other than the embodiments described above.
１　光走査装置
１０　駆動制御部
４０　直流電圧重畳部
５０，５０’，１５０　共振型偏向素子
５２，５２’，１５２　偏向面
８０　温度検出部 DESCRIPTION OF SYMBOLS 1 Optical scanning apparatus 10 Drive control part 40 DC voltage superimposition part 50,50 ', 150 Resonance type deflection | deviation element 52,52', 152 Deflection surface 80 Temperature detection part

Claims (5)

  1. 　入射する光束を偏向する偏向面を有し、共振により前記偏向面が軸周りに揺動する共振型偏向素子と、
    　前記共振型偏向素子を駆動する駆動信号の周波数を変化させ、前記偏向面の揺動振幅を検出して、前記共振型偏向素子固有の共振周波数を判定し、この共振周波数から所定周波数だけずれた周波数の前記駆動信号で前記共振型偏向素子を駆動した後、前記駆動信号の振幅を変更して前記偏向面の揺動振幅を所定値にする駆動手段と、を備える光走査装置。     A resonant deflecting element having a deflecting surface for deflecting an incident light beam, and the deflecting surface swings around an axis by resonance;
    The frequency of the drive signal for driving the resonance type deflection element is changed, the oscillation amplitude of the deflection surface is detected, the resonance frequency unique to the resonance type deflection element is determined, and the resonance frequency is deviated by a predetermined frequency. An optical scanning device comprising: driving means for changing the amplitude of the drive signal to drive the oscillation amplitude of the deflection surface to a predetermined value after driving the resonant deflection element with the drive signal of frequency.
  2. 　前記共振型偏向素子は、メタル基板上に前記偏向面を含む領域が形成されたＭＥＭＳであり、
    　前記駆動手段は、前記共振周波数から所定周波数だけ高い周波数の前記駆動信号で前記共振型偏向素子を駆動した後、前記偏向面の揺動振幅を所定値にする
    ことを特徴とする請求項１に記載の光走査装置。     The resonant deflection element is a MEMS in which a region including the deflection surface is formed on a metal substrate,
    2. The drive means according to claim 1, wherein after the resonance type deflection element is driven with the drive signal having a frequency higher than the resonance frequency by a predetermined frequency, the swing amplitude of the deflection surface is set to a predetermined value. The optical scanning device described.
  3. 　前記共振型偏向素子は、シリコン基板上に前記偏向面を含む領域が形成されたＭＥＭＳであり、
    　前記駆動手段は、前記共振周波数から所定周波数だけ低い周波数の前記駆動信号で前記共振型偏向素子を駆動した後、前記偏向面の揺動振幅を所定値にする
    ことを特徴とする請求項１に記載の光走査装置。     The resonant deflection element is a MEMS in which a region including the deflection surface is formed on a silicon substrate,
    2. The drive means according to claim 1, wherein after the resonance type deflection element is driven with the drive signal having a frequency lower than the resonance frequency by a predetermined frequency, the swing amplitude of the deflection surface is set to a predetermined value. The optical scanning device described.
  4. 　前記共振型偏向素子又はその周囲の温度を検出する温度検出手段を備え、
    　前記所定周波数は、前記温度検出手段によって検出された温度に基づいた周波数としたことを特徴とする請求項１に記載の光走査装置。     A temperature detecting means for detecting the temperature of the resonant deflection element or its surroundings;
    The optical scanning device according to claim 1, wherein the predetermined frequency is a frequency based on a temperature detected by the temperature detection unit.
  5. 　請求項１に記載の光走査装置を備え、画像信号に応じた強度の光束を前記光走査装置により走査し、ユーザの少なくとも一方の眼に向けて出射させることで、画像を表示することを特徴とする網膜走査型の画像表示装置。 The optical scanning device according to claim 1, wherein a light beam having an intensity corresponding to an image signal is scanned by the optical scanning device and emitted toward at least one eye of a user to display an image. Retina scanning type image display device.
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