JP6808506B2 - Optical scanning device - Google Patents

Description

The present invention relates to an optical scanning device including an optical deflector.

A MEMS (Micro Electro Mechanical Systems) optical deflector is known. The optical deflector has a mirror portion, a support portion, and an actuator, and the actuator is interposed between the mirror portion and the support portion and is deformed according to the voltage applied to the piezoelectric film to form the mirror portion. Is reciprocally rotated around a predetermined axis, and the mirror unit emits the incident light from the light source as reflected light in a direction corresponding to the rotation angle around the axis. Further, as an actuator, an optical deflector using an actuator in which a plurality of cantilever are connected by a meander pattern in order to obtain a large driving force is known (Example: Patent Document 1).

Patent Document 1 discloses an optical scanning device that prevents a movable portion, which is a mirror portion, from falling at one end side due to its own weight and tilting with respect to the horizontal when the movable portion is arranged horizontally instead of vertically. There is. According to the optical scanning device, the positions where the left and right actuators connect the movable parts from both the left and right sides are set at both ends of the diagonal line of the rectangular movable part, for example, without being on the same side with respect to the rotation axis. Actuators support the moving parts from opposite sides to the axis of rotation.

Japanese Unexamined Patent Publication No. 2012-198314

In a typical optical scanning device, the optical deflector is enclosed in a package and fixed to a substrate. Then, the light from the light source enters the mirror portion of the light deflector in the package, and the reflected light reflected by the mirror portion is emitted from the package as scanning light.

In the optical scanning device, it is desirable that a predetermined direction with respect to the substrate is set as the reference emission direction, and the reflected light from the mirror portion becomes the reference emission direction when the mirror portion is not driven by the actuator. This is because the drive voltage of the actuator of the optical deflector is determined based on the difference between the emission direction in which light is to be emitted and the reference emission direction.

However, in an actual optical scanning device, the light emitting direction when the actuator is not driven varies depending on the optical scanning device, and deviates from the reference emitting direction. Therefore, it is necessary to calibrate the emission direction of the light from the optical scanning device to match the reference emission direction. Specifically, the causes of the variation are (a) variation in the manufacture of an actuator composed of a plurality of cantilever levers in the meander pattern arrangement of the optical deflector, (b) variation in the fixing angle of the optical deflector in the package, and (C) Variations in the mounting angle of the package on the substrate and the like can be mentioned.

The optical scanning device of Patent Document 1 only prevents tilting due to the weight of the movable portion when the initial position of the movable portion is set horizontally, and does not establish a reference emission direction in response to manufacturing variations.

An object of the present invention is to provide an optical scanning device capable of establishing a reference emission direction and accurately controlling the reciprocating rotation of the mirror unit.

The optical scanning apparatus of the present invention
Light source and
It has a mirror portion, a support portion, and an actuator, and the actuator is interposed between the mirror portion and the support portion and is deformed according to a voltage applied to the piezoelectric film to determine the mirror portion. A light deflector that reciprocates around the axis of the mirror and emits incident light from the light source as reflected light in a direction corresponding to the rotation angle around the axis.
An optical scanning device including a control unit that applies a voltage to the piezoelectric film to control the rotation angle of the mirror unit around the axis.
The actuator has a plurality of cantilever coupled in a meander pattern and individually having the piezoelectric film.
When the plurality of cantilever levers are numbered in the order of arrangement from the support portion to the mirror portion,
The odd-numbered cantilever can be divided into an odd-numbered cantilever for calibration and an odd-numbered cantilever for reciprocating rotation.
The even-numbered cantilever can be divided into an even-numbered cantilever for calibration and an even-numbered cantilever for reciprocating rotation.
The control unit
On the piezoelectric film of the odd-numbered cantilever for calibration and the even-numbered cantilever for calibration, the emission direction of the reflected light when the odd-numbered cantilever for reciprocating rotation and the even-numbered cantilever for reciprocating rotation are not driven is the reference emission direction. A voltage for reciprocating rotation is applied to the piezoelectric film of the odd-numbered cantilever for reciprocating rotation and the even-numbered cantilever for reciprocating rotation, and a periodic fluctuation voltage for reciprocating the mirror portion around the axis is applied. And.

According to the present invention, the odd-numbered cantilever and the even-numbered cantilever are classified into a calibration cantilever in the reference emission direction and a reciprocating cantilever that reciprocates the mirror portion around the axis, respectively. Thereby, the calibration of the reference emission direction can be performed by the odd-numbered cantilever for calibration and the even-numbered cantilever for calibration, and the reference emission direction can be established. Further, since the odd-numbered cantilever for calibration and the even-numbered cantilever for calibration are held in a stationary state without vibrating while the mirror portion is rotating, the reference emission direction can be stabilized.

Then, after establishing the reference emission direction, the reciprocating rotation of the mirror portion around the axis is controlled by the reciprocating rotation odd-numbered cantilever and the reciprocating rotation even-numbered cantilever. The control of the even-numbered cantilever can be generalized and accurate regardless of the individual optical scanning device.

In the optical scanning apparatus of the present invention, preferably, the control unit applies the calibration voltage to the piezoelectric film of the calibration odd-numbered cantilever and the calibration even-numbered cantilever, and the mirror around the axis. A bias voltage is applied to change the central rotation angle of the reciprocating rotation range of the unit.

According to this configuration, the calibration odd-numbered cantilever and the calibration even-numbered cantilever simultaneously calibrate the reference emission direction and shift the scanning area. As a result, the scanning region can be shifted while ensuring a large reciprocating rotation angle range by the reciprocating rotation odd-numbered cantilever and the reciprocating rotation even-numbered cantilever.

In the optical scanning apparatus of the present invention, preferably, the odd-numbered cantilever for calibration and the even-numbered cantilever for calibration are cantilever numbers 1 and 2, respectively.

According to this configuration, the odd-numbered cantilever for calibration and the even-numbered cantilever for calibration do not intervene between the odd-numbered cantilever for reciprocating rotation and the even-numbered cantilever for reciprocating rotation and the mirror portion. Therefore, since the vibration transmitted between the reciprocating rotation odd number cantilever and the reciprocating rotation even number cantilever and the mirror portion does not pass through the calibration odd number cantilever and the calibration even number cantilever, the calibration odd number cantilever and the calibration even number cantilever. It is possible to stabilize the support in the reference emission direction by the number cantilever.

The block diagram of the optical scanning apparatus. The figure which shows the connection relationship between each element in a control part, and each electrode pad of an optical deflector. Wiring diagram of the right half of the optical deflector. The figure which shows the relationship between the initial emission direction and the reference emission direction in an optical scanning apparatus when there is no manufacturing variation. The figure which shows the relationship between the initial emission direction and the reference emission direction in an optical scanning apparatus when there is a manufacturing variation. The graph which shows the relationship between the reciprocating rotation voltage which a control part applies to the piezoelectric film of the reciprocating rotation cantilever of an outer actuator, and the rotation angle of a mirror part around the 2nd axis. The figure which shows the time change of the reciprocating rotation voltage which a control part applies to an outer actuator. A graph showing the relationship between the calibration angle and the calibration voltage.

FIG. 1 is a configuration diagram of the optical scanning device 20. The optical scanning device 20 includes an optical deflector 1, a laser light source 21, and a control unit 22. The light deflector 1 is enclosed in a package 23 having a light transmitting window on the top surface. The control unit 22 and the package 23 are mounted on the substrate 24 (FIGS. 4A and 4B). The laser light source 21 may be mounted on the substrate 24, or may be arranged at a predetermined position different from the substrate 24 so that the emission destination of the laser light is directed to the optical deflector 1 on the substrate 24. is there.

First, the light deflector 1 will be described. The light deflector 1 is a kind of MEMS. The optical deflector 1 includes a circular mirror portion 2 rotatably arranged in the center, a circular annular movable frame 3 that surrounds the mirror portion 2 from the outside, and a rectangular fixed frame 4 that surrounds the movable frame 3 from the outside. It has.

For convenience of explanation of the structure, a three-axis coordinate system including an X-axis, a Y-axis, and a Z-axis is defined. The center O as the origin of the three-axis coordinate system is set at the center of the circular mirror portion 2 on the mirror surface 2a. The X-axis, Y-axis and Z-axis are orthogonal to each other at the center O. The X-axis and the Y-axis are set parallel to the long side and the short side of the rectangular fixed frame 4, respectively. The Z axis is set parallel to the thickness direction of the fixed frame 4.

Further, for convenience of explanation, the side where the mirror surface 2a of the mirror portion 2 can be seen in the Z-axis direction is defined as the front side of the optical deflector 1, and the opposite side is defined as the back side. Further, the X-axis direction and the Y-axis direction are defined as the vertical direction and the horizontal direction of the front view of the optical deflector 1.

The normal line 25 (FIGS. 4A and 4B) of the mirror surface 2a passes through the center O and is perpendicular to the mirror surface 2a. The mirror portion 2 can reciprocate around the first axis and the second axis, which will be described later. The normal 25 of the mirror surface 2a fluctuates as the mirror portion 2 reciprocates. However, the center O, which is the center of the mirror portion 2, remains immobile even during the reciprocating rotation of the mirror portion 2. The mirror portion 2 of FIG. 1 is shown in a state where the normal line 25 of the mirror surface 2a coincides with the Z axis.

A pair of torsion bars 5a and 5b project from both sides of the mirror portion 2 along the diameter in the Y-axis direction in the circular mirror portion 2 when viewed from the front, and at both ends of the semicircular inner actuators 6a and 6b at the protruding ends. It is combined. The torsion bars 5a and 5b can be extended to the inner circumference of the movable frame 3 and connected to the inner circumference.

The inner actuators 6a and 6b are arranged on the left and right sides of the mirror portion 2 in the front view, and are formed so as to have a semicircular shape individually in the front view and a circumferential shape as a whole. The axes of the torsion bars 5a and 5b coincide with the first axis in which the mirror portion 2 reciprocates. When the normal 25 of the mirror surface 2a coincides with the Z axis, the first axis overlaps the Y axis. As the mirror portion 2 reciprocates around the first axis, the mirror portion 2 swings left and right in front view.

The inner actuators 6a and 6b are surrounded by an annular movable frame 3 from the outside. The handle portions 12a and 12b extend along the X-axis and connect the midpoint of the outer semicircle of the inner actuators 6a and 6b and the inner peripheral circle of the circular hole of the annular movable frame 3 at both ends. ..

The inner actuators 6a and 6b are composed of one cantilever, and the cantilever has a piezoelectric film formed on one side of a substrate layer (not shown) like the cantilever 15s of the outer actuators 7a and 7b described later. It has an upper electrode and a lower electrode that sandwich the piezoelectric film from the upper side and the lower side (the substrate layer side is defined as the lower side) in the Z-axis direction. The inner actuators 6a and 6b are piezoelectric actuators having a unimorph structure that are curved and deformed by the driving voltage of the unipolar supplied to the piezoelectric film.

The axes of the handle portions 12a and 12b are not the second axis 27 (FIG. 4) itself, but define the second axis 27. The second axis 27 reciprocates around the Y axis as the mirror portion 2 reciprocates around the first axis while maintaining its Y-axis position at the Y-axis position of the handle portions 12a and 12b. Move.

The outer actuators 7a and 7b are arranged on the left and right sides of the movable frame 3 in front view inside the fixed frame 4, and the inner peripheral edge of the fixed frame 4 and the movable frame 3 at the proximal end side coupling portion 18 and the distal end side coupling portion 19 It is connected to the outer periphery. Each of the cantilever 15s described below constituting the outer actuators 7a and 7b has a piezoelectric film formed on one side of the substrate layer, and is a piezoelectric actuator having a unimorph structure that is curved and deformed by the driving voltage of the unipolar supplied to the piezoelectric film. Is.

The outer actuators 7a and 7b reciprocate the movable frame 3 around the X-axis. As the movable frame 3 reciprocates around the X axis, the mirror portion 2 reciprocates around the second axis 27. As the mirror portion 2 reciprocates around the second axis 27, the mirror portion 2 swings up and down in front view.

Both the first axis and the second axis 27 are set on a plane including the mirror surface 2a and are orthogonal to each other at the center O. The second axis 27 coincides with the X axis when the normal 25 of the mirror surface 2a coincides with the Z axis. The intersection angle between the second axis 27 and the X axis at the center O changes as the mirror portion 2 reciprocates around the first axis. The first axis and the movable frame 3 reciprocate integrally around the X axis.

Hereinafter, the torsion bars 5a and 5b are collectively referred to as "torsion bars 5" when not particularly distinguished. The inner actuators 6a and 6b are collectively referred to as "inner actuator 6" unless otherwise specified. The outer actuators 7a and 7b are collectively referred to as "outer actuator 7" unless otherwise specified. The handle portions 12a and 12b are collectively referred to as "handle portion 12" when not particularly distinguished.

The outer actuator 7 is a plurality of cantilever coupled by the folded-back portion 16 so as to form a meander pattern, and is the calibration cantilever 15CR (1), 15CR (2) and the reciprocating cantilever 15CC (3), 15CC (4). , 15CC (5). Details of the calibration cantilever 15CR (1) and 15CR (2) and the reciprocating cantilever 15CC (3), 15CC (4) and 15CC (5) will be described later. When it is not necessary to distinguish the calibration cantilever 15CR (1), 15CR (2) and the reciprocating cantilever 15CC (3), 15CC (4), 15CC (5) individually, they are collectively referred to as "cantilever 15".

The outer actuator 7 is coupled to the inner circumference of the fixed frame 4 and the outer circumference of the movable frame 3 at both ends via the proximal end side coupling portion 18 and the distal end side coupling portion 19, respectively. The plurality of cantilever 15s are arranged in a row in the X-axis direction with the longitudinal direction aligned in the Y-axis direction.

The base end side coupling portion 18 is separated from the X axis in the Y axis direction + side and is located at a position substantially close to the inner peripheral side of the long side portion of the fixed frame 4, and the tip end side coupling portion 19 exists on the X axis. .. That is, among the cantilever 15, the cantilever closest to the movable frame 3 in the X-axis direction is half the length of the other cantilever 15.

The calibration cantilever 15CR (1) and 15CR (2) and the reciprocating cantilever 15CC (3), 15CC (4) and 15CC (5) will be described. With respect to the cantilever 15, the number Nos. 1-No. Add 5 (Nos. 1 to 5). No. 1-No. The cantilever 15 of No. 4 has the same length in the longitudinal direction, and No. The longitudinal dimension of the cantilever 15 of No. 5 is No. 1-No. It is about 1/2 of the longitudinal dimension of the cantilever 15 of 4.

When a voltage is applied to the piezoelectric film, each cantilever 15 is convexly curved toward the back surface side. Each cantilever 15 increases the amount of curvature as the applied voltage increases.

No. 1, No. Since the cantilever 15 of 2 is used for calibration of the reference emission direction Ro (FIG. 4A, etc.) described later, it is indicated by the calibration cantilevers 15CR (1) and 15CR (2), respectively. The calibration cantilever 15CR (1) corresponds to the "calibration odd-numbered cantilever" of the present invention, and the calibration cantilever 15CR (2) corresponds to the "calibration even-numbered cantilever" of the present invention. When it is not necessary to distinguish the calibration cantilever 15CR (1) and 15CR (2) individually, they are collectively referred to as "calibration cantilever 15CR".

No. 3-No. Since the cantilever 15 of 5 is used for the reciprocating rotation of the mirror portion 2 around the second axis, the cantilever 15CC (3), 15CC (4), and 15CC (5) for reciprocating rotation are instructed, respectively. The reciprocating rotation cantilevers 15CC (3) and 15CC (5) correspond to the "reciprocating rotation odd number cantilever" of the present invention, and the reciprocating rotation cantilever 15CC (4) corresponds to the "reciprocating rotation even number cantilever" of the present invention. Corresponds to. When it is not necessary to individually distinguish the reciprocating cantilever 15CC (3), 15CC (4), and 15CC (5), they are collectively referred to as "reciprocating cantilever 15CC".

In front view of the optical deflector 1, the left electrode pads 8a1 to 8a6 are arranged on the left short side portion of the fixed frame 4, and the optical deflector is attached to a corresponding element existing in the left half portion with respect to the mirror portion 2. It is connected via the buried wiring or the buried metal layer in 1. When viewed from the front of the optical deflector 1, the electrode pads 8b1 to 8b6 on the right side are arranged on the short side portion on the right side of the fixed frame 4, and the optical deflector is attached to a corresponding element existing in the right half portion with respect to the mirror portion 2. It is connected via the buried wiring or the buried metal layer in 1. Hereinafter, the electrode pads 8a1 to 8a6 and 8b1 to 8b6 are collectively referred to as "electrode pads 8" when not particularly distinguished.

FIG. 2 shows the connection relationship between each element in the control unit 22 and the electrode pad 8 of the optical deflector 1. The output voltage of the variable DC power supplies 101 and 102 is variable. The variable DC power supply 101 is connected to the electrode pads 8a1 and 8b1. The variable DC power supply 102 is connected to the electrode pads 8a2 and 8b2. The voltage applied by the variable DC power supplies 101 and 102 to the electrode pads 8a1 and 8b1 is maintained constant during the reciprocating rotation of the mirror unit 2.

The reciprocating rotation voltage generation units 103 and 104 generate a reciprocating rotation voltage Vc that reciprocates the mirror unit 2 around the second axis. Specific examples of the reciprocating rotation voltage Vc are periodic fluctuation voltages such as a sawtooth wave (FIG. 6), a triangular wave, and a sine waveform. The reciprocating rotation voltage Vc output by the reciprocating rotation voltage generation unit 103 and the reciprocating rotation voltage Vc output by the reciprocating rotation voltage generation unit 104 are in a positive phase and a reverse phase relationship. The bias voltage generation unit 105 generates a bias voltage Vb (a voltage that biases the minimum value of Vc above 0V in order to perform unipolar drive). The adder 106 adds the output voltages of the reciprocating rotation voltage generation unit 103 and the bias voltage generation unit 105, and outputs them to the electrode pads 8a3 and 8b3. The adder 107 adds the output voltages of the reciprocating rotation voltage generation unit 104 and the bias voltage generation unit 105, and outputs them to the electrode pads 8a4 and 8b4.

The sinusoidal generators 110 and 111 generate sinusoidal voltages Vs of equal amplitude and frequency. The sine wave voltage Vs output by the sine wave generator 110 and the sine wave voltage Vs output by the sine wave generator 111 have a positive phase and a negative phase relationship, and are output to the electrode pads 8a5 and 8b5, respectively. .. Since the resonance of the mirror portion 2 around the first axis is used for the reciprocating rotation of the mirror portion 2 around the first axis, the frequency of the sinusoidal voltage Vs is set to be equal to the resonance frequency. .. The ground 112 is connected to the electrode pads 8a6 and 8b6.

FIG. 3 is a wiring diagram of the right half of the optical deflector 1. Although the wiring on the left half of the optical deflector 1 is not shown, the corresponding elements have the same connection relationship as the corresponding elements on the left half.

In FIG. 3, the surface terminals 31d1 to 31d5 are formed on the upper surfaces of the calibration cantilever 15CR (1) and 15CR (2) and the reciprocating cantilever 15CC (3) -15CC (5), respectively. Of the electrodes sandwiching the piezoelectric film from both sides, the electrodes on the front side) are connected. The wiring 31b1 connects the electrode pad 8b1 and the surface terminal 31d1. The wiring 32b1 connects the electrode pad 8b2 and the surface terminal 31d2. The wiring 33b1 connects the electrode pad 8b3 and the surface terminals 31d3 and 31d5. The wiring 34b1 connects the electrode pad 8b4 and the surface terminal 31d4.

The electrode pad 8b5 is connected to the upper electrode of the inner actuator 6b by a wiring (not shown). The electrode pads 8b6 are connected to a common ground electrode layer (not shown) as an embedded metal layer in the right half of the optical deflector 1. The ground electrode layer constitutes a lower electrode in the inner actuator 6b and the outer actuator 7b.

The optical deflector 1 is enclosed in a package 23, and each terminal of the package 23 and each of the electrode pads 8a and 8b are connected by a bonding wire (not shown). As described above, the optical deflector 1 is mounted on the substrate 24 (FIGS. 4A and 4B) together with the control unit 22. The laser light source 21 emits the incident light La of the light deflector 1 from the outside of the package 23 toward the center O of the mirror surface 2a of the mirror portion 2 of the light deflector 1. The package 23 is formed with a transmission window that allows light to enter and exit.

The mirror unit 2 reflects the incident light La incident on the center O in a direction corresponding to the rotation angle around the first axis and the second axis 27, and the scanning light Lb (even the reflected light of the incident light La) is reflected. There is), and the light is emitted to a predetermined irradiation area. In FIG. 1, the incident light La is directly incident on the mirror portion 2 from the laser light source 21 and is directly directed to the irradiation region. In the actual product, the optical system is arranged on the outside of the package 23 to change the optical path.

FIG. 4A shows the relationship between the initial emission direction Ri and the reference emission direction Ro in the optical scanning apparatus 20 when there is no manufacturing variation. FIG. 4B shows the relationship between the initial emission direction Ri and the reference emission direction Ro in the optical scanning apparatus 20 when there are manufacturing variations. The manufacturing variations of FIGS. 4A and 4B are (a) manufacturing variations of the outer actuator 7 composed of a plurality of cantilever 15s in the meander pattern arrangement of the optical deflector 1, and (b) sticking of the optical deflector 1 in the package 23. It is the total variation of the variation of the angle and (c) the variation of the mounting angle of the package 23 on the substrate 24. Therefore, the inclination of the mirror portion 2 and the direction of the scanning light Lb shown in FIGS. 4A and 4B are shown in a state where the package 23 in which the optical deflector 1 is enclosed is mounted on the substrate 24. ..

In FIGS. 4A and 4B, the auxiliary line H1 and the auxiliary line Q1 are shown for convenience of explanation. The auxiliary line H1 passes through the center O at the base of the normal line 25 and is drawn parallel to the surface of the substrate 24. The auxiliary line Q1 passes through the center O at the base of the normal line 25 and is drawn perpendicular to the surface of the substrate 24. In the optical scanning device 20 with no manufacturing variation, the normal line 25 of the mirror unit 2 coincides with the auxiliary line Q1. For convenience of explanation, in this optical scanning device 20, the rotation angle θ of the mirror portion 2 around the second axis 27 when the normal line 25 coincides with the auxiliary line Q1 is defined as 0 °.

The reference emission direction Ro is defined as a plane on the upper surface of the substrate 24 or a predetermined direction with respect to a predetermined normal erected on the plane. The reference emission direction Ro calculates or calculates the voltage applied to the piezoelectric film of the outer actuator 7 corresponding to the rotation angle θ when the control unit 22 controls the rotation angle θ of the mirror unit 2 around the second axis 27. Be the basis for deciding. For example, when the control unit 22 controls the emission direction of light from the optical scanning device 20 to Ru (not shown), the control unit 22 is around the second axis 27 corresponding to the reference emission direction Ro and the emission direction Ru. The applied voltage of each piezoelectric film of the outer actuator 7 is calculated based on the difference θu−θo of the rotation angles θo and θu (θu is not shown) of the mirror portion 2 of the above, and is applied to the upper electrode of the cantilever 15. The initial emission direction Ri is defined as the emission direction of the reflected light Lb from the optical scanning device 20 when the inner actuator 6 and the outer actuator 7 are not driven.

Since the optical scanning device 20 of FIG. 4A has no manufacturing variation, the initial emission direction Ri coincides with the reference emission direction Ro. For convenience of explanation, the initial emission direction Ri is represented by the rotation angle θ of the mirror unit 2, and is assumed to be θi. In FIG. 4A, θo = θi. At this time, calibration of the light emission direction from the optical scanning device 20 for establishing the reference emission direction Ro can be omitted.

In FIG. 4B, since the normal line 25 deviates from the auxiliary line Q1, the initial emission direction Ri deviates from the direction of the initial emission direction Ri in FIG. 4A. As a result, θo ≠ θi, and the emission direction of the light from the optical scanning device 20 for establishing the reference emission direction Ro is calibrated. Details of the calibration will be described in FIG. Briefly, the calibration voltage corresponding to θo−θi is supplied to the electrode pads 8a1, 8b1, 8a2, 8b2 and applied to the piezoelectric film of the calibration cantilever 15CR.

Before explaining the characteristic action of the light deflector 1, the general action will be outlined. In the optical deflector 1, the mirror portion 2 reciprocates around the axis (first axis) of the torsion bar 5 by the operation of the inner actuator 6. The mirror portion 2 is also included in the mirror surface 2a of the mirror portion 2 by the operation of the outer actuator 7, and the second axis 27 is used as the axis of the handle portions 12a and 12b orthogonal to the first axis at the center O of the mirror surface 2a. It reciprocates around.

In a typical optical scanning device 20, the scanning light Lb scans the irradiation region in the lateral direction by reciprocating rotation of the mirror portion 2 around the first axis. Further, the scanning light Lb scans the irradiation region in the vertical direction by the reciprocating rotation of the mirror portion 2 around the second axis 27. The horizontal and vertical directions are typically aligned in the horizontal and vertical directions, respectively, when the optical scanning device 20 is equipped in an image generating device such as a projector.

For example, the frequency of the reciprocating rotation of the mirror portion 2 around the first axis is 18 kHz, and the frequency of the reciprocating rotation of the mirror portion 2 around the second axis 27 is 60 Hz. Resonance is used for the reciprocating rotation of the mirror portion 2 around the first axis. Resonance is not used for the reciprocating rotation of the mirror portion 2 around the second axis 27, and only the acting force of the outer actuator 7 is used. The frequency of the reciprocating rotation of the mirror portion 2 around the second axis 27 matches the frequency of the reciprocating rotation voltage Vc.

Next, the action that characterizes the optical scanning device 20 will be described. FIG. 5 is a graph showing the relationship between the reciprocating rotation voltage Vc applied to the piezoelectric film of the reciprocating cantilever 15CC of the outer actuator 7 by the control unit 22 and the rotation angle θ of the mirror unit 2 around the second axis 27. is there. In FIG. 5, the reciprocating rotation voltage Vco is applied to the piezoelectric films of the reciprocating rotation cantilever 15CC (3) and 15CC (5). The reciprocating rotation voltage Vce is applied to the piezoelectric film of the reciprocating rotation cantilever 15CC (4).

The rotation angle θ in FIG. 5 means the rotation angle after the reference emission direction Ro is established by the calibration cantilever 15CR, and the normal line 25 and the auxiliary line Q1 overlap each other. According to FIG. 5, when the rotation angle θ is 0 °, the reciprocating rotation voltages Vco and Vce are both set to V1. When the rotation angle θ is, for example, β1, the reciprocating rotation voltage Vco has a value Vco1, and the reciprocating rotation voltage Vce has a value Vce1.

The reciprocating rotation voltages Vco and Vce are in a mutually opposite phase relationship at each rotation angle θ. On the other hand, there is a withstand voltage Vw for the piezoelectric film of each cantilever 15. Therefore, the maximum value Vmax of the reciprocating rotation voltages Vco and Vce is Vmax ≦ Vw.

The reciprocating cantilever 15CC (3), 15CC (5) and the reciprocating cantilever 15CC (4) are reciprocating in opposite phases to each other. Rotational voltages Vco and Vce are applied to reciprocate the mirror portion 2 around the second axis 27 in the range of −β to β. The magnitude relationship between the reciprocating rotation voltages Vco and Vce reverses at θ = 0 °.

FIG. 6 is a diagram showing a time change of the reciprocating rotation voltage applied by the control unit 22 to the outer actuator 7. The reciprocating rotation voltage Vco is supplied to the reciprocating rotation cantilever 15CC (3) and 15CC (5) of the outer actuator 7. The reciprocating rotation voltage Vce is supplied to the reciprocating rotation cantilever 15CC (4) of the outer actuator 7. The reciprocating rotation voltages Vco and Vce change with a saw wave as a waveform of a periodic fluctuation voltage, and are in a mutually opposite phase relationship.

Next, a method of calibrating the reference rotation angle θo due to manufacturing variations of the optical scanning apparatus 20 will be described. FIG. 7 is a graph showing the relationship between the calibration angle (= θo−θi) and the calibration voltage Vr. Vw and Vmax in FIG. 7 correspond to those in FIG. The calibration voltage Vro is applied to the piezoelectric film of the calibration cantilever 15CR (1). The calibration voltage Vre is applied to the piezoelectric membrane of the calibration cantilever 15CR (2).

The optical scanning device 20 makes it possible to calibrate the reference emission direction Ro in the range where the rotation angle of the mirror portion 2 around the second axis 27 is in the range of −γ to γ. According to FIG. 7, when the calibration angle is 0 °, the calibration voltages Vro and Vre are both set to V2. When the calibration angle is, for example, γ1, the calibration voltage Vro is set to the value Vro1, and the calibration voltage Vre is set to the value Vre1. When the reciprocating rotation cantilever 15CC (5) does not exist and the reciprocating rotation cantilever 15CC (4) is connected to the movable frame 3, γ = β and V2 = V1.

For example, when the calibration angle (= θo−θi) = γ1, the calibration voltage Vro = Vro1 and the calibration voltage Vre = Vre1 are set, and Vro1 is applied to the piezoelectric film of the cantilever 15 of the calibration cantilever 15CR (1). Then, Vre1 is applied to the piezoelectric film of the calibration cantilever 15CR (2) so that the amount of curvature of the calibration cantilever 15CR (1)> the amount of curvature of the calibration cantilever 15CR (2). As a result, the rotation angle θ of the mirror portion 2 increases, and the light emission direction approaches the upper surface of the substrate 24 to be the reference emission direction Ro (see FIG. 4B).

On the other hand, the drive voltage of the calibration cantilever 15CR is the calibration voltage Vro (or Vre) + the bias voltage Vb (≦ Vmax). A predetermined increment can be added to the bias voltage Vb by the voltage for unipolar driving of the calibration cantilever 15CR. By adjusting the bias voltage Vb, the central rotation angle of the reciprocating rotation range of the mirror portion 2 around the second axis 27 changes, and the scanning region in which the scanning light emitted from the optical scanning device 20 is scanned is the second. The two axes are displaced in the direction corresponding to the rotation direction around the line 27. As a result, the scanning region can be shifted while maintaining a large reciprocating rotation angle range by the reciprocating rotation cantilever 15CC.

(Modification example)
The optical deflector 1 of the embodiment is an optical deflector 1 that rotates in two orthogonal axes. In the optical deflector 1 of the present invention, the mechanism portion (movable frame 3, torsion bar 5, inner actuator 6, etc.) for rotating the mirror portion 2 around the first axis is omitted in the optical deflector 1 of the embodiment. , The tip side coupling portion 19 of the outer actuator is directly coupled to the peripheral edge of the mirror portion 2, and the mirror portion 2 reciprocates only around the second axis 27 (in this case, the second axis 27 corresponds to the X axis). It may be a uniaxially rotating optical deflector whose configuration has been changed as described above.

In the embodiment, the fixed frame 4 as the support portion surrounds the mirror portion 2 and the outer actuator 7 as the actuator. The support portion of the present invention may be disposed on only one side of the mirror portion without surrounding the mirror portion.

The laser light source 21 of the embodiment corresponds to the light source of the present invention. The light source of the present invention is not limited to the laser light source 21 as long as it emits beam-shaped light.

In the embodiment, the calibration cantilever 15CR (1) and 15CR (2) correspond to the calibration odd-numbered cantilever and the calibration even-numbered cantilever of the present invention, respectively, and the reciprocating cantilever 15CC (3) and 15CC (5) correspond to each other. It corresponds to the "odd-numbered cantilever for reciprocating rotation" of the present invention, and the cantilever 15CC (4) for reciprocating rotation corresponds to the "even-numbered cantilever for reciprocating rotation" of the present invention. In the present invention, if at least one or more odd-numbered cantilever for calibration, even-numbered cantilever for calibration, odd-numbered cantilever for reciprocating rotation, and even-numbered cantilever for reciprocating rotation are secured, and the odd-numbered and even-numbered numbers are maintained, respectively. The arrangement order of the odd-numbered cantilever for calibration, the even-numbered cantilever for calibration, the odd-numbered cantilever for reciprocating rotation, and the even-numbered cantilever for reciprocating rotation in the coupling of the mianda pattern may be arbitrary.

However, when the odd-numbered cantilever for calibration and the even-numbered cantilever for calibration of the present invention are selected as the odd-numbered cantilever and the even-numbered cantilever on the most proximal side coupling portion 18 side, the calibration cantilever 15CR and the reciprocating cantilever 15CC are used. It will not intervene with the mirror portion 2. As a result, the calibration cantilever 15CR is suppressed from vibrating due to the vibration of the reciprocating cantilever 15CC and the mirror portion 2, and the rotation control of the mirror portion 2 around the axis can be stabilized.

In the light deflector 1 of the embodiment, the mirror portion 2 has a circular shape, but the mirror portion 2 does not have to be circular. For example, it can be a square or a rectangle.

1 ... Optical deflector, 2 ... Mirror part, 4 ... Fixed frame (support part), 7 ... Outer actuator (actor), 15CR (1) ... Cantilever (odd number cantilever for calibration) ), 15CR (2) ... Cantilever (even numbered cantilever for calibration), 15CR (3) ... Cantilever (odd numbered cantilever for reciprocating rotation), 15CR (4) ... Cantilever (even numbered cantilever for reciprocating rotation) ), 15CR (5) ... Cantilever (odd number cantilever for reciprocating rotation), 18 ... Base end side coupling part, 19 ... Tip side coupling part, 20 ... Optical scanning device, 21 ... Laser light source (light source), 22 ... control unit, 24 ... substrate, 25 ... normal line, 27 ... second axis.

Claims (3)

Light source and
It has a mirror portion, a support portion, and an actuator, and the actuator is interposed between the mirror portion and the support portion and is deformed according to a voltage applied to the piezoelectric film to determine the mirror portion. A light deflector that reciprocates around the axis of the mirror and emits incident light from the light source as reflected light in a direction corresponding to the rotation angle around the axis.
An optical scanning device including a control unit that applies a voltage to the piezoelectric film to control the rotation angle of the mirror unit around the axis.
The actuator has a plurality of cantilever coupled in a meander pattern and individually having the piezoelectric film.
When the plurality of cantilever levers are numbered in the order of arrangement from the support portion to the mirror portion,
The odd-numbered cantilever can be divided into an odd-numbered cantilever for calibration and an odd-numbered cantilever for reciprocating rotation.
The even-numbered cantilever can be divided into an even-numbered cantilever for calibration and an even-numbered cantilever for reciprocating rotation.
The control unit
On the piezoelectric film of the odd-numbered cantilever for calibration and the even-numbered cantilever for calibration, the emission direction of the reflected light when the odd-numbered cantilever for reciprocating rotation and the even-numbered cantilever for reciprocating rotation are not driven is the reference emission direction. A voltage for reciprocating rotation is applied to the piezoelectric film of the odd-numbered cantilever for reciprocating rotation and the even-numbered cantilever for reciprocating rotation, and a periodic fluctuation voltage for reciprocating the mirror portion around the axis is applied. Optical scanning device. In the optical scanning apparatus according to claim 1,
In addition to the calibration voltage, the control unit applies the calibration voltage to the piezoelectric film of the calibration odd-numbered cantilever and the calibration even-numbered cantilever, and the central rotation angle of the reciprocating rotation range of the mirror unit around the axis. An optical scanning device characterized in that a bias voltage is applied to change the voltage. In the optical scanning apparatus according to claim 1 or 2.
The calibration odd-numbered cantilever and the calibration even-numbered cantilever are optical scanning devices whose numbers are No. 1 and No. 2, respectively.