JP2014048571A - Optical deflector, image forming apparatus, and image projection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve linearity of the rotation amplitude in an optical deflector that rotatably supports a movable part with meandering beam parts.SOLUTION: An optical deflector 101 has a movable part that has a reflection surface, meandering beam parts that rotatably support the movable part, a frame member that supports the meandering beam parts, and a plurality of piezoelectric members provided to respective meandering beams of the meandering beam parts. To the plurality of piezoelectric members provided to the respective meandering beams of the meandering beam parts, different triangular waves having a rise time and a fall time replaced with each other in the same frequency are applied every other one to drive the meandering beam parts, so as to rotationally swing the movable part.

Description

  The present invention relates to an optical deflector that deflects and scans a light beam, an image forming apparatus including the optical deflector, and an image projection apparatus.

  In recent years, as a means for deflecting and scanning a light beam, a movable part provided with a reflective surface and an elastic beam part are integrally formed on a semiconductor substrate by a micromachining technique for finely processing silicon or glass using semiconductor manufacturing technology. Small optical deflectors (optical deflecting elements) have been developed.

  When using such an optical deflector to draw an image by deflecting and scanning light from a light source, it is desirable to increase the proportion of time for scanning in one direction as much as possible. For example, when raster scanning is performed in the main scanning and sub-scanning directions as shown in FIG. 10, the drawing speed is kept constant during drawing, and when drawing of one frame is finished and drawing of the next frame is started, In the scanning direction, it is desirable to return to the first row as soon as possible from the last row.

  11 to 14 are graphs showing the relationship between the amplitude angle (rotation angle) of the reflecting surface of the optical deflector and time. Here, as shown in FIG. 11, if only the substantially linear region s is used by sine wave drive, the time available for drawing is shortened. Therefore, it is desirable to drive as shown in FIG. 12, but in practice it is as shown in FIG. In the case of FIG. 13 as well, as shown in FIG. 14, it is desirable to make the drawing effective time as long as possible and the return time as short as possible. In the resonance drive, the amplitude angle characteristics as shown in FIGS. 13 and 14 cannot be obtained. Therefore, it is possible to reduce the rigidity of the beam supporting the movable portion provided with the reflection surface as much as possible so that the desired drive control can be performed. Necessary.

  Conventionally, in an optical deflector using micromachining technology, as shown in FIG. 15, it is known to form a beam portion in a meandering manner as a configuration for reducing the rigidity of the beam portion that supports the movable portion (for example, Patent Document 1, Patent Document 2, Patent Document 3, etc.). In FIG. 15, reference numeral 10 denotes a movable portion having a reflecting surface, and the movable portion 10 is supported by a pair of beam portions (meandering beam portions) 11 a and 11 b formed by meandering with a plurality of folded portions. The meandering beam portions 11 a and 11 b are supported by the frame member 12. In the meandering beam portions 11a and 11b, an independent piezoelectric member (piezoelectric layer) 13 is provided for each adjacent meandering beam portion. By applying a voltage having a different phase to each of the piezoelectric members 13 to generate warpage in the meandering beam portions 11a and 11b, as shown in FIG. 16, adjacent beam portions have different directions. As a result, the movable part 10 is accumulated at a large angle around the X axis.

  As described above, as the optical deflector, the movable portion is supported by the meandering beam portion (meandering beam portion), so that the rigidity is reduced as compared with a simple torsion beam, and it is large with a smaller force. A twist angle can be obtained.

  By the way, in the optical deflector, the resonance frequency is determined by the weight of the movable part and the rigidity of the support beam, and even when driven at a low frequency that deviates from the resonance frequency, the vibration of the resonance frequency component rides on the optical deflector. May be disturbed. The same applies to an optical deflector using a meandering beam portion.

  For example, as shown in FIG. 17, it is assumed that every other piezoelectric member 13 provided on the meandering beam portions 11a and 11b is A and B, and different voltages are applied to the respective movable members 10 to drive the amplitude. Now, in order to obtain the amplitude characteristics as shown in FIGS. 12 and 13, consider the applied voltage as shown in FIG. 18 in which one of the piezoelectric members A and B is resting when warping occurs. . In FIG. 18, a waveform c is an applied voltage of A, and a waveform d is an applied voltage of B. When the piezoelectric member 13 is a monomorph, even if it is driven at 0 V or less, there is a possibility that the deformation amount of the piezoelectric element with respect to the unit voltage may be reduced or the polarization may be lost. The voltages c and d are applied to the A and B piezoelectric members 13 within a range equal to or lower than the upper limit voltage.

  In this case, ideally, as shown in FIG. 12 and FIG. 12, the amplitude angle of the movable part should change linearly with a triangular wave periodically, and the difference between the rise time and the fall time should be large. . However, in actuality, as shown in FIG. 19, vibration with a period of the resonance frequency rides and does not change linearly.

  It is known that in an optical deflector, if a notch filter is inserted to properly cut the vibration at the resonance frequency in order to cut the vibration component due to the resonance frequency, the vibration corresponding to the resonance frequency is eliminated. However, there arises a problem that the entire range of use is reduced due to the occurrence of swells as a whole or rounding as shown in FIG.

  In the optical deflectors described in Patent Documents 1 to 3, the linearity of the rotational amplitude of the movable part is not considered.

  It is an object of the present invention to improve the linearity (linearity) of the rotational amplitude of a movable part in an optical deflector that rotatably supports the movable part with a meandering beam part.

The present invention supports a movable portion having a reflective surface, a meandering beam portion formed by meandering having a plurality of folded portions, which rotatably supports the movable portion, and the meandering beam portion. A frame member and a plurality of piezoelectric members respectively provided on each meandering beam portion of the meandering beam portion;
In the optical deflector in which a bending deformation of each of the meandering beam portions of the meandering beam portion is accumulated by applying a voltage to the piezoelectric member to drive the meandering beam portion, and the movable portion rotates and swings.
A voltage signal of a different triangular wave in which the rising time and the falling time are switched at the same frequency is applied to each other of the plurality of piezoelectric members provided in each of the meandering beam portions of the meandering beam portion, The meandering beam portion is driven.

  According to the optical deflector of the present invention, the linearity of the rotational amplitude (amplitude angle) of the movable part is improved.

1 is an overall configuration diagram of an optical scanning device according to an embodiment. It is a figure which shows an example of the applied voltage signal of this invention. It is a figure which shows the amplitude angle characteristic of the optical deflector at the time of applying the applied voltage signal of FIG. It is a figure explaining the phase shift of the applied voltage signal of FIG. It is a whole block diagram of the optical scanning device concerning another embodiment. It is a figure which shows an example of a two-way optical deflector. 1 is an overall configuration diagram of an image processing apparatus according to an embodiment. 1 is an overall configuration diagram of an image projection apparatus according to an embodiment. It is a whole block diagram of the image projector which concerns on another embodiment. It is a figure explaining the raster scan of drawing. It is a figure which shows the amplitude angle characteristic in a sine wave drive. It is a figure which shows an ideal amplitude angle characteristic. It is a figure which shows the actual amplitude angle characteristic with respect to FIG. It is the figure which showed the relationship between the drawing effective time in FIG. 13, and return time. It is a figure which shows an example of the optical deflector made into object by this invention. It is a figure explaining the drive operation | movement of the meandering beam part of the optical deflector of FIG. It is a figure explaining the relationship between the piezoelectric member on a meandering beam part, and an applied voltage signal. It is a figure which shows an example of the conventional applied voltage signal. It is a figure which shows the amplitude angle characteristic of the optical deflector at the time of applying the applied voltage signal of FIG. It is a figure which shows the amplitude angle characteristic of the optical deflector at the time of using a notch filter.

  Embodiments of the present invention will be described below with reference to the drawings. Hereinafter, the optical deflector and its driving means are referred to as an optical scanning device.

  FIG. 1 is an overall configuration diagram of an optical scanning device according to the present embodiment. The optical scanning device includes a laser light source (LD) 100, an optical deflector (optical deflecting element) 101 that deflects and scans a light beam of laser light emitted from the laser light source 100, and a laser for driving the laser light source 100. Light source drive unit 102, optical deflector drive unit 103 for driving optical deflector 101, storage unit 104 for storing the drive frequency of optical deflector 101, and other drive conditions, and laser light source drive unit 102 and optical deflection It has a control unit 105 that controls the operation of the instrument drive unit 103 and the like.

  The optical deflector 101 has the same configuration as that shown in FIG. 15, and includes a movable portion 10 having a reflecting surface, a pair of serpentine beam portions 11a and 11b that rotatably support the movable portion 10, and the serpentine beam portions 11a, A frame member 12 that supports 11b and a plurality of piezoelectric members (piezoelectric layers) 13 provided independently for each meandering beam portion of the meandering beam portions 11a and 11b.

  Here, the optical deflector 101 has the same frequency for every other piezoelectric member 13 provided on each of the meandering beam portions 11a and 11b by the optical deflector driving unit 103. A voltage signal of a different triangular wave (sawtooth wave) in which the rising time and the falling time are switched is applied, the meandering beam portions 11a and 11b are driven, and the movable portion 10 is rotationally driven. This will be specifically described below.

  As shown in FIG. 17, a plurality of piezoelectric members 13 provided on the meandering beam portions (each beam portion in the direction perpendicular to the rotation axis XX) of the meandering beam portions 11a and 11b are placed one by one. A and B. Here, a voltage signal (hereinafter, voltage signal a) indicated by waveform a in FIG. 2 is applied to the piezoelectric member A, and a voltage signal (hereinafter referred to as waveform b) in FIG. 2 is applied to the piezoelectric member B. The voltage signal b) is applied. FIG. 3 shows the relationship between the amplitude angle of the movable part 10 and time in this case.

  As shown in FIG. 18, a voltage signal c in which one half of one cycle is 0V, slowly rises in the other half and returns at high speed, and a voltage signal d that rises at high speed and returns slowly, and the other half is 0V. 2, two voltage signals a and b of a triangular wave (sawtooth wave) in which the rise time and the fall time in one cycle are interchanged are meandered in the meandering beam portions 11 a and 11 b as shown in FIG. 2. The linearity of the rotational amplitude (amplitude angle) of the movable portion 10 is higher when the meandering beam portions 11a and 11b are driven by applying the piezoelectric members 13 to every other beam portion (see FIG. 3).

  Note that, depending on the optical deflector, sufficient linearity may not be obtained with the voltage signals a and b having the same phase in which the rise time and the fall time are simply switched as shown in FIG. In this case, the phases of the voltage signal a and the voltage signal b are relatively changed. Experimentally, the linearity of the rotational amplitude of the movable part 10 is improved by shifting the phase of the voltage signal a applied to A of the piezoelectric member 13 and the voltage signal b applied to B and adjusting the shift amount. It was confirmed. This is because the vibration of the frequency component excited by the drive of the piezoelectric member A and the vibration of the frequency component excited by the drive of the piezoelectric member B are shifted in phase so that the unnecessary vibrations cancel each other. It is thought that. If the amount of phase shift of the voltage signals a and b applied to A and B of the piezoelectric member 13 can be adjusted so as to cancel out unnecessary vibrations generated in the piezoelectric members 13 A and B, the movable part 10 The linearity of the rotation amplitude can be further improved.

  Specifically, as shown in FIGS. 4A and 4B, the meandering beam is relatively shifted while the phases of the voltage signal a applied to A and the voltage signal b applied to B of the piezoelectric member 13 are relatively shifted. By driving the portions 11a and 11b, the change in the linearity of the rotational amplitude of the movable portion 10 is examined, and the phase shift amount where the linearity is most improved is found. This phase shift amount is stored in the storage unit 104. When the optical deflector 100 is driven, the control unit 105 reads the phase shift amount from the storage unit 104 and sets it in the optical deflector driving unit 103. The optical deflector driving unit 103 relatively shifts the phase of the voltage signal a applied to A and the voltage signal b applied to B of the piezoelectric member 13 by the set phase shift amount (for example, FIG. ) M, n in FIG. 4B, etc.), the meandering beam portions 11a and 11b are driven.

  In addition, depending on the optical deflector, sufficient linearity may not be obtained only by relatively shifting the phase of the voltage signal a applied to A of the piezoelectric member 13 and the voltage signal b applied to B. In this case, the drive frequency (frequency of the voltage signals a and b) is changed. It has been experimentally confirmed that the linearity of the rotational amplitude of the movable part 10 can be improved by changing the drive frequency when the vibration of the resonance frequency component is applied to the rotational amplitude of the movable part 10 and the linearity is impaired. It was. This is considered to be because, depending on the drive frequency, there is a condition that the vibrations of the resonance frequency components excited by the amplitude drive of the piezoelectric member A and the piezoelectric member B cancel each other. Therefore, the drive frequency is changed to check the change in linearity, and the drive is performed at the drive frequency where the linearity is the best.

  Specifically, the meandering beam portions 11a and 11b are driven while changing the frequency of the voltage signal a applied to A of the piezoelectric member 13 and the voltage signal b applied to B, and the rotational amplitude of the movable portion 10 is linear. The frequency change is examined, the frequency with the best linearity is found, and stored in the storage unit 104. When the optical deflector 100 is driven, the control unit 105 reads the corresponding frequency (driving frequency) from the storage unit 104 and sets it in the optical deflector driving unit 103. The optical deflector driving unit 103 drives the meandering beam portions 11a and 11b by setting the frequency of the voltage signal a applied to A of the piezoelectric member 13 and the frequency of the voltage signal applied to B to the set frequency. At the same time, the control unit 105 sets the light emission timing of the laser light source 100 in the laser light source driving unit 102 in accordance with the drive frequency. Thereby, even if the drive frequency changes, the laser light source driving unit 102 can drive the laser light source 100 accordingly.

  The adjustment / setting of the drive frequency may be performed in combination with the above-described adjustment / setting of the phase. Thereby, the linearity of the rotational amplitude of the movable part 10 can be further improved.

  However, when setting the drive frequency, it is desirable to use a frequency that is not substantially an integral number of the resonance frequency of the structural portion of the optical deflector. For example, when the resonance frequency is 360 Hz, it is desirable to avoid frequencies of around 180 Hz, around 120 Hz, around 90 Hz, around 60 Hz, etc. as the driving frequency (frequency of the voltage signals a and b). Experiments have shown that when the drive frequency is a fraction of the resonance frequency or a value in the vicinity thereof, even if the frequency and / or the relative phase changes slightly, the drive is performed at a frequency that is separated from the integral fraction of the resonance frequency. Compared with the case where it did, it resulted in the linearity of the rotational amplitude of the movable part 10 being impaired significantly.

  Since the resonance frequency itself is not constant due to manufacturing variations of optical deflectors and usage environment, there is a margin so that the resonance frequency does not fluctuate and the drive frequency does not become a value of 1 / integer of the resonance frequency. Drive frequency must be set.

  FIG. 5 shows an overall configuration diagram of an optical scanning device according to another embodiment. The optical scanning device includes a laser light source (LD) 100, an optical deflector (optical deflecting element) 101 that deflects and scans a light beam of laser light emitted from the laser light source 100, and a laser for driving the laser light source 100. Operation of the light source driving unit 102, the optical deflector driving unit 103 for driving the optical deflector 101, the storage unit 104 for storing the driving frequency and other driving conditions, the laser light source driving unit 102, the optical deflector driving unit 103, etc. And a temperature sensor (temperature detecting means) 106 for detecting the ambient temperature of the optical deflector 101.

  The optical deflector 101 has the same configuration as that of FIG. 16 as in FIG. 1, and includes a movable portion 10 having a reflecting surface, a pair of meandering beam portions 11a and 11b that rotatably support the movable portion 10, and the meandering shape. A frame member 12 that supports the beam portions 11a and 11b and a plurality of piezoelectric members 13 provided independently for each meandering beam portion of the meandering beam portions 11a and 11b. Note that the temperature sensor 106 is formed integrally with the optical deflector 101.

  As in FIG. 1, the optical deflector 101 is provided for every other piezoelectric member 13 provided on each meandering beam portion of the meandering beam portions 11a and 11b by the optical deflector driving unit 103 (see FIG. 1). 17 (for each of A and B of the piezoelectric member 13), different triangular wave voltage signals (a and b in FIG. 2) with the same rising frequency and falling time are applied at the same frequency, respectively, and the meandering beam portions 11a, 11b is driven and the movable part 10 is rotationally driven.

  The feature of this embodiment is that the relative phase, frequency (drive frequency), voltage value, and the like of the two voltage signals a and b are changed according to a change in the ambient temperature of the optical deflector 101. The movable portion 10 and the meandering beam portions 11a and 11b, which are the main components of the optical deflector 101, change in elastic coefficient or change in shape due to expansion / contraction due to a temperature change such as a use environment. As a result, the linearity of the rotational amplitude of the movable part 10 is impaired due to a change in the resonance frequency. As the elastic coefficient changes, the amplitude sensitivity (the amplitude angle that increases or decreases per unit voltage) also changes.

  Therefore, in the present embodiment, a temperature sensor 106 that detects the temperature around the optical deflector 101 is provided, and the driving condition is changed according to the ambient temperature of the optical deflector 101. Specifically, for each temperature, the relative phase and frequency of the voltage signals a and b applied to every other piezoelectric member 13 provided in each of the meandering beam portions of the meandering beam portions 11a and 11b. Then, by changing the voltage value, the meandering beam portions 11a and 11b are driven to find the phase shift amount, frequency, and applied voltage that improve the linearity and amplitude sensitivity of the rotational amplitude of the movable portion 10 most. For each temperature, the found optimum values of the phase shift amount, frequency, and applied voltage are stored in the storage unit 104. When the optical deflector 101 is actually driven, the control unit 105 receives from the storage unit 104 the phase shift amount and frequency (frequency) of the voltage signals a and b according to the ambient temperature of the optical deflector 101 detected by the temperature sensor 106. Driving frequency) and the optimum value of the applied voltage are read out and set in the optical deflector driving unit 103. At the same time, the control unit 105 sets the light emission timing of the laser light source 100 in the laser light source driving unit 102 in accordance with the driving frequency.

  As described above, according to the present embodiment, the phase shift amount, the drive frequency, the applied voltage, and the like of the two voltage signals a and b can be adjusted to optimum values according to the change in the ambient temperature of the optical deflector 101. Therefore, the linearity and amplitude sensitivity of the rotational amplitude of the movable part are improved.

  So far, as shown in FIG. 15, an optical deflector that generates a tilt of the reflecting surface in one direction has been targeted. On the other hand, in this embodiment, in the optical deflector that generates the inclination of the reflecting surface in a plurality of directions, the driving means described in the first and second embodiments is nested in the rotating portion around the axis in at least one direction. To improve the linearity of the rotational amplitude of the reflecting surface. Here, a two-way optical deflector that generates the tilt of the reflecting surface in two directions will be described as an example.

  FIG. 6 shows a configuration example of the two-way optical deflector. In FIG. 6, reference numeral 20 denotes a movable portion having a reflecting surface, and the movable portion 20 is supported by a pair of torsion bars 21a and 21b. The ends of the torsion bars 21a and 21b are supported by one ends of the piezoelectric cantilevers 22a to 22d, respectively, and the other ends of the piezoelectric cantilevers 22a to 22d are supported by the movable frame 23, respectively. The movable frame 23 is supported by a pair of beam portions (meandering beam portions) 24 a and 24 b formed by meandering with a plurality of folded portions, and the meandering beam portions 24 a and 24 b are supported by the frame member 25. Has been. The meandering beam portions 24a and 24b are provided with a plurality of independent piezoelectric members 26 for each meandering beam portion.

  In the configuration of FIG. 6, by driving the piezoelectric cantilevers 22a to 22d, rotation is given to the torsion levers 21a and 21b that support the movable portion 20, and the movable portion 20 rotates and swings around the Y axis. On the other hand, by driving the meandering beam portions 24a and 24b, the movable frame 23 rotates around the X axis, and accordingly, the movable portion 20 also rotates and swings around the X axis. Specifically, the rise time and the fall time are switched at the same frequency for every other piezoelectric member 26 provided independently for each meandering beam portion of the meandering beam portions 24a and 24b. Different triangular wave voltage signals (a and b in FIG. 2) are applied to drive the meandering beam portions 24a and 24b. Thereby, the linearity of the rotation amplitude around the X axis of the movable part 20 is improved. Also in this case, the phase and frequency of the two voltage signals a and b may be changed as necessary.

  The present embodiment provides an image forming apparatus in which the optical deflector that deflects and scans light in the uniaxial direction described in the first and second embodiments is mounted as a constituent member of an optical writing unit.

  FIG. 7 shows an overall configuration diagram of an example of the image forming apparatus of the present embodiment. In FIG. 7, reference numeral 1001 denotes an optical writing unit, which emits a laser beam to a surface to be scanned and writes an image. Reference numeral 1002 denotes a photosensitive drum as an image carrier that provides a surface to be scanned as an object to be scanned by the optical writing unit 1001.

  The optical writing unit 1001 scans the surface (scanned surface) of the photosensitive drum 1002 in the axial direction of the photosensitive drum 1002 with one or a plurality of laser beams modulated by the recording signal. The photosensitive drum 1002 is rotationally driven in the direction of an arrow 1003, and an optical latent image is formed on the surface charged by the charging unit 1004 by optical scanning by the optical writing unit 1001. The electrostatic latent image is visualized as a toner image by the developing unit 1005, and the toner image is transferred to the recording paper 1007 by the transfer unit 1006. The transferred toner image is fixed on the recording paper 1007 by the fixing unit 1008. Residual toner is removed by the cleaning unit 1009 from the surface portion of the photosensitive drum that has passed the transfer unit 1006 facing portion of the photosensitive drum 1002.

  A configuration using a belt-like photoconductor in place of the photoconductor drum 1002 is also possible. Further, the toner image may be temporarily transferred to a transfer medium other than the recording paper, and the toner image may be transferred from the transfer medium to the recording paper and fixed.

  The optical writing unit 1001 is described in the first and second embodiments, as a light source unit 1020 as a laser element that emits one or a plurality of laser beams modulated by a recording signal, a light source driving unit 1500 that modulates the laser beams. The optical deflector 1002 that deflects the laser beam in one axial direction, and the laser beam (light beam) modulated by the recording signal from the light source unit 1020 is formed on the mirror surface of the mirror substrate of the optical deflector 1022. An imaging optical system 1021 for scanning, and a scanning optical system 1023 which is a means for imaging one or a plurality of laser beams reflected and deflected by a mirror surface on the surface (scanned surface) of the photosensitive drum 1002 Etc. The optical deflector 1022 is incorporated in the optical writing unit 1001 in a form mounted on a circuit board 1025 together with an integrated circuit (driving means) 1024 for driving the optical deflector 1022.

  The optical deflector 1022 consumes less power for driving than the conventional rotary polygon mirror, which is advantageous for power saving of the image forming apparatus. Further, since the wind noise during vibration of the mirror substrate of the optical deflector 1022 is smaller than that of the rotary polygon mirror, it is advantageous for improving the quietness of the image forming apparatus. Furthermore, the optical deflector 1022 requires much less installation space than the rotary polygon mirror, and also has a small amount of heat generation, so that it can be easily downsized, and therefore advantageous for downsizing the image forming apparatus. is there. In addition, the linear performance of scanning is good, and deterioration of image quality can be prevented.

  Note that the conveyance mechanism of the recording paper 1007, the driving mechanism of the photosensitive drum 1002, the control means such as the developing means 1005 and the transfer means 1006, the driving system of the light source unit 1020, and the like may be the same as those in the conventional image forming apparatus. Is omitted.

  The present embodiment provides an image projection apparatus in which the optical deflector that deflects light in the biaxial direction described in the second embodiment is mounted.

  FIG. 8 shows an overall configuration diagram of an example of the image projection apparatus of the present embodiment. In FIG. 8, 2001-R is a laser light source that emits red (R) laser light, 2001-G is a laser light source that emits green (G) laser light, and 2001-B is blue (B) laser light. This is a laser light source that emits light. R, G, and B laser beams emitted from these laser light sources 2001-R, 2001-G, and 2001-B are combined by a cross dichroic prism 2002 and are incident on a reflection surface of an optical deflector 2003. The optical deflector 2003 deflects and scans the combined laser light input to the reflection surface in the biaxial direction (main scanning / sub-scanning direction) and projects the resultant light onto the projection surface (screen) 2004.

  Here, the optical deflector 2003 is configured as shown in FIG. For example, around the Y axis (in the main scanning direction), the piezoelectric cantilevers 22a to 22d, which are highly rigid spring systems, are driven at a resonance frequency, and the movable unit 20 is rotated and amplified at high speed using resonance characteristics. On the other hand, around the X axis (in the sub-scanning direction), the meandering beam portions 24a and 24b of a low rigidity spring system are driven at a frequency lower than the resonance frequency to rotate the movable portion 20 at low speed. That is, the difference between the frequencies around the X-axis drive and the Y-axis drive is made sufficiently large. Thereby, a large speed difference can be obtained between the X axis and the Y axis. Therefore, a light beam can be scanned two-dimensionally by the optical deflector 2003, and an image can be projected two-dimensionally on a projection surface (screen) 2004. In addition, for every other piezoelectric layer 26 provided independently for each meandering beam portion of the meandering beam portions 24a and 24b, different triangular wave voltages with the same rising frequency and falling time are switched at the same frequency. By applying and driving the serpentine beam portions 24a and 24b, the linear performance of the rotation amplitude around the X axis, that is, the linear performance of scanning in the sub-scanning direction is improved, and the deterioration of the image quality can be prevented.

  FIG. 9 is a diagram showing another configuration diagram of the image projection apparatus of the present embodiment. This is because R, G, and B laser beams emitted from the laser light sources 2001-R, 2001-G, and 2001-B are incident on the optical deflector 2003 without being combined into one optical path. Each of them is scanned two-dimensionally and projected onto a projection surface (screen) 2004. The operation of the optical deflector 2003 is basically the same as that in FIG.

  8 and 9 show the configuration examples for projecting a color image, but it is also possible to project a monochrome image by using one laser light source.

DESCRIPTION OF SYMBOLS 10 Movable part 11a, 11b Meandering beam part 12 Frame member 13 Piezoelectric member 20 Movable part 21a, 21b Torsion bar 22a-22d Piezoelectric cantilever 23 Movable frame 24a, 24b Meandering beam part 25 Frame member 26 Piezoelectric member 101 Optical deflector a , B Voltage signal

JP 2008-35600 A JP 2009-223165 A JP 2009-265362 A

Claims (8)

A movable part having a reflective surface; a meandering beam part formed by meandering with a plurality of folded parts that rotatably supports the movable part; and a frame member that supports the meandering beam part; A plurality of piezoelectric members respectively provided on each meandering beam portion of the meandering beam portion;
In the optical deflector in which a bending deformation of each of the meandering beam portions of the meandering beam portion is accumulated by applying a voltage to the piezoelectric member to drive the meandering beam portion, and the movable portion rotates and swings.
A voltage signal of a different triangular wave in which the rising time and the falling time are switched at the same frequency is applied to each other of the plurality of piezoelectric members provided in each of the meandering beam portions of the meandering beam portion, An optical deflector in which a meandering beam is driven.   The optical deflector according to claim 1, wherein the phase of the voltage signal is relatively changed in accordance with linearity of the rotation amplitude of the movable part.   The optical deflector according to claim 1, wherein the frequency of the voltage signal is changed in accordance with linearity of the rotation amplitude of the movable part.   4. The optical deflector according to claim 3, wherein the frequency of the voltage signal does not become a value of 1 / integer of the resonance frequency of the structural portion of the optical deflector. 5.   A temperature sensor for detecting a temperature around the optical deflector is provided, and at least one of a frequency, a phase, and a voltage value of the voltage signal is changed according to the temperature detected by the temperature sensor. Item 4. The optical deflector according to Item 1. An optical deflector that generates a tilt of the reflecting surface in a plurality of directions,
A light characterized in that the driving means of the optical deflector according to any one of claims 1 to 5 is arranged in a nested manner in a rotating portion around an axis in at least one direction, and the reflection surface is rotated and amplified. Deflector.   6. An image forming apparatus comprising: the optical deflector according to claim 1; and a light beam deflected and scanned by the optical deflector to form an image on a photosensitive member. apparatus.   An image projection apparatus comprising: the optical deflector according to claim 6, wherein an optical beam is deflected and scanned by the optical deflector to project an image on a projection surface.

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