JP2017083677A - Optical scanning element and projection device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress degradation of swing accuracy of a swing member and condensation on a reflective surface.SOLUTION: An optical scanning element 2 has a swing member 21 which has a reflective surface 211 for reflecting light from a light source 100 and is formed to have a swing center line C1 that is offset, with respect to a center of the swing member 21 in a thickness direction thereof, in a direction along the reflective surface 211, and to have end faces shaped such that the reflective surface 211 and a reflective surface 212 overlap with a single circle centered about the swing center line C1 at least at portions of ends of the swing member 21.SELECTED DRAWING: Figure 6B

Description

  The present invention relates to an optical scanning element that moves a light spot irradiated to an irradiation target area and scans the target area with the light spot, and relates to a projection apparatus that uses the optical scanning element.

  The projection apparatus includes an optical device that scans the irradiation target area with the light beam by swinging a reflection surface that reflects the light beam from the light source to the irradiation handling area. Examples of the optical device include an optical device described in Japanese Patent Application Laid-Open No. 2010-102157.

  In the optical device described in Japanese Patent Application Laid-Open No. 2010-102157, a movable plate having a reflective film (reflective surface) that reflects light from a light source is connected to a support frame via a pair of elastic support portions (torsion bars). Yes. Accordingly, the movable plate is supported so as to be rotatable around the rotation axis. And the magnet is attached so that it may have a pair of magnetic poles in which the polarity is different from the surface opposite to the reflecting surface of the movable plate with the rotation shaft in between. A coil is provided so as to face the magnet. By applying an alternating current to the coil, the movable plate swings around the rotation shaft while twisting and deforming the elastic support portion. In the optical device, the power source (actuator) is an electromagnetic type, but a piezoelectric type or an electrostatic type may be used in addition to this.

  In order to reduce the size and increase the functionality of the optical device, the movable plate is driven at a high speed and a large deflection angle. By making the movable plate at a high speed and a large deflection angle, foreign matters such as dust, dust, moisture, and oil are attracted to and attached to the reflecting surface by the airflow generated around the movable plate. In the optical device described in Japanese Patent Application Laid-Open No. 2010-102157, the side surface of the movable plate has a shape protruding from the outer edge of the reflecting surface to the opposite side of the rotation shaft. By adopting the shape in which the side surface protrudes in this way, even if an air flow is generated by the swinging of the movable plate, the foreign matter adheres to the side surface, so that a decrease in the reflectance of the reflecting surface can be suppressed. In addition, the optical device described in JP 2010-102157 A has a configuration in which the movable plate rotates around one axis, but is not limited thereto, and each of the two axes that intersect (orthogonal) intersect. Some optical devices are configured to rotate about the center.

JP 2010-102157 A

  However, when the movable plate is driven at a high speed and a large deflection angle, the pressure difference between the reflecting surface side and the opposite surface side of the movable plate becomes large, and the drive (angle) of the movable plate relative to the drive signal is caused by the pressure difference. Response deteriorates, that is, a response delay occurs. There is a risk that the accuracy of the oscillation speed, frequency, and deflection angle may be reduced due to the pressure difference. Furthermore, in a humid environment, if the atmospheric pressure on the reflective surface side decreases due to a difference in atmospheric pressure, condensation occurs on the reflective surface, which may cause a delay in response or lead to a decrease in reflectance.

  In view of the above, an object of the present invention is to provide an optical scanning element capable of suppressing a decrease in swing accuracy of a reflecting surface and suppressing the occurrence of condensation on the reflecting surface.

  In order to achieve the above object, the present invention has a flat plate-like rocking portion including a reflecting surface that reflects light from a light source and an opposite surface, and the rocking portion is located on the reflecting surface side from the center in the thickness direction. And the swinging portion is formed such that the opposite surface is hidden by the reflecting surface when viewed in the thickness direction, and at least part of the outer peripheral surface portion There is provided an optical scanning element including a pressure difference adjusting unit having a reflecting surface protruding outward in a direction perpendicular to the thickness direction from the opposite surface.

  According to this configuration, in the pressure difference adjustment unit, the difference between the distance from the swing center line to the end of the reflecting surface and the distance from the swing center line to the end of the opposite surface is reduced. . As a result, the difference in linear velocity between the reflecting surface and the opposite surface at the time of swinging can be kept small, and the pressure difference between the surface of the reflecting surface and the surface of the opposite surface can be kept low. Thereby, the rocking accuracy (response, rocking angle, frequency, etc.) of the rocking part can be increased. In addition, by suppressing the difference in atmospheric pressure between the reflecting surface and the opposite surface to be small, it is possible to suppress the occurrence of condensation even when the swinging unit is driven in a high humidity environment. It is possible to suppress problems that the weight balance of the oscillating portion is lost due to dew condensation and the oscillating accuracy is lowered or that the light beam cannot be accurately reflected due to dew condensation on the reflecting surface.

  In the above configuration, the pressure difference adjusting unit of the swinging unit may have the same distance from the swinging center line to the outer peripheral edge of the reflecting surface and the outer peripheral edge of the opposite surface. . With such a configuration, such a oscillating portion allows the distance from the end portion that is the farthest part from the oscillating center line when the oscillating portion oscillates to the reflecting surface. Since it can be made the same on the side and the opposite surface side, the pressure difference between the reflecting surface and the opposite surface can be further reduced.

  In the above-described configuration, the pressure difference adjusting unit of the swing unit may include at least a portion farthest from the swing center line of the swing unit when the swing unit is viewed in the thickness direction. . By configuring in this way, the portion including the portion farthest from the rocking center line, which is the portion where the atmospheric pressure fluctuation of the rocking portion is the largest, is the end face shape. The pressure difference on the opposite surface can be kept low.

  In the above configuration, in the pressure difference adjustment unit of the swing unit, a shape cut by a plane perpendicular to the swing center line of a surface adjacent to the reflection surface and the opposite surface is centered on the swing center line. It may be a circular arc. With this configuration, the end face of the swinging portion at the time of swinging moves on the single circular arc, so that atmospheric pressure fluctuation is unlikely to occur.

  The said structure WHEREIN: The shape where the said rocking | swiveling center line and the said reflective surface overlap may be sufficient as the said rocking | swiveling part. With this configuration, when the oscillating portion oscillates around the oscillation center line, the reflection surface itself also oscillates around the oscillation center line. When viewed in the thickness direction of the moving part), the deviation of the reflecting surface is suppressed. As a result, the effective area of the reflecting surface that can be irradiated with the light beam can be increased, that is, the spot shape (spot diameter) of the light beam can be increased. In addition, since the oscillation center line is formed on the reflection surface, the length from the oscillation center line to the end surface can be easily adjusted, and the pressure difference between the reflection surface and the opposite surface can be easily achieved with a simple configuration. A small rocking part can be formed.

  The said structure WHEREIN: The shape provided with several recessed part may be sufficient as the part corresponding to the said atmospheric | air pressure difference adjustment part of the side surface of the said rocking | swiveling part. According to this configuration, the airflow around the oscillating portion is likely to be turbulent due to the concave portion, and the airflow is difficult to be separated due to the turbulent flow. Thereby, it can suppress that the said rocking | swiveling part at the time of rocking | pulling is pulled to the other side by peeling of an airflow, and can raise rocking | fluctuation precision.

  In the above configuration, the swinging portion may be a circle when viewed in the thickness direction.

  According to the present invention, it is possible to provide an optical scanning element capable of suppressing a decrease in the swing accuracy of the swing unit and suppressing the occurrence of condensation on the reflecting surface.

1 is a schematic view of an image forming apparatus using a projection apparatus according to the present invention. It is a figure which shows schematic arrangement | positioning of a projection apparatus. It is a block diagram of the projection apparatus shown in FIG. It is a schematic plan view of the optical scanning element provided with the piezoelectric actuator. It is a side view of the mirror body shown in FIG. It is sectional drawing which shows the rocking | fluctuation state of the mirror body shown in FIG. It is sectional drawing which shows the cross-sectional shape of the mirror body shown in FIG. It is a side view of the mirror of the optical scanning element concerning this invention. It is the figure which expanded the mirror of the optical scanning element concerning this invention. It is sectional drawing which cut | disconnected the mirror body shown in FIG. 8 by the IX-IX line. It is sectional drawing which cut | disconnected the mirror body shown in FIG. 8 by XX. It is a side view of the mirror of the optical scanning element concerning this invention. It is sectional drawing which cut | disconnected the mirror body shown in FIG. 11 by the plane orthogonal to a rocking | fluctuation center line. It is sectional drawing of the mirror body of the optical scanning element concerning this invention. It is the schematic of the projector using the projection apparatus concerning this invention. It is a top view of the optical scanning element concerning this invention. It is a top view of the optical scanning element concerning this invention.

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

<First Embodiment>
FIG. 1 is a schematic view of an image forming apparatus using a projection apparatus according to the present invention. The projection apparatus shown in FIG. 1 is used in an image forming apparatus, and is used as part of an exposure apparatus that exposes a photoconductor as an image carrier. As shown in FIG. 1, in the image forming apparatus Pt, the charging unit Ef, the exposure device Lt, the developing unit Dp, the transfer roller Tr, the cleaning unit CL, and the charge eliminating unit Re are arranged in this order with the photoreceptor Pc as the center. ing.

  The photoreceptor Pc has a cylindrical shape and rotates around the axis. The charging unit Ef gives (charges) a constant charge on the surface of the photoreceptor Pc. Examples of the charging unit Ef include a non-contact type such as a corotron type and a scotron type, and a contact type using a charging roller or a charging brush, but are not limited thereto.

  The photoconductor Pc is an insulator in a dark place (dark place), and has a property that when irradiated with light (when exposed), a portion irradiated with the light becomes a conductor. The exposure apparatus Lt uses this property to generate an electrostatic latent image on the surface of the photoreceptor Pc. In other words, the exposure apparatus Lt scans the surface of the rotating photosensitive member Pc with a light beam (laser light) in the length direction of the photosensitive member Pc and exposes the surface of the photosensitive member Pc electrostatically. Generate a latent image. The exposure apparatus Lt includes a projection apparatus A that includes a light source unit 100 and an optical scanning unit 200.

  The developing unit Dp supplies (charges) toner having a charge to the photoreceptor Pc on which the electrostatic latent image is formed, thereby attracting the toner to the surface of the photoreceptor Pc and generating (developing) a toner image. . The toner image is generated in the same manner as the photosensitive member Pc by adsorbing the toner having a charge opposite to that charged on the photosensitive member Pc to the portion where the charge is not lost by the exposure or the portion where the charge is lost. Examples thereof include those that push in polar toner.

  The transfer roller Tr is disposed adjacent to the photoreceptor Pc so that the central axis is parallel to the axis of the photoreceptor Pc. The transfer roller Tr is a roller for transferring a toner image to a recording paper Pp that is a transfer target supplied to a nip portion between the transfer roller Tr and the photosensitive member Pc. The transfer roller Tr applies a charge (transfer bias) opposite to that of the toner, so that the toner is sucked from the photoreceptor Pc and transferred to the recording paper Pp.

  The cleaning unit CL removes the toner remaining on the photoconductor Pc. Examples of a method for removing the toner remaining on the photosensitive member Pc include, but are not limited to, a method of adsorbing with a charging brush and a method of scraping with a blade formed of rubber or the like. The surface of the photosensitive member Pc from which the remaining toner has been removed by the cleaning unit CL is removed by the charge removal unit Re in preparation for the next printing. Further, the recording paper Pp to which the toner image is transferred is heated and pressed by a fixing roller (not shown), and the toner image (image) is fixed on the recording paper Pp.

  Next, details of the projection apparatus according to the present invention and the optical scanning element provided in the projection apparatus will be described with reference to the drawings. FIG. 2 is a diagram showing a schematic arrangement of the projection apparatus, and FIG. 3 is a block diagram of the projection apparatus shown in FIG.

  As shown in FIGS. 2 and 3, the projection apparatus A includes a light source unit 100, an optical scanning unit 200, and a processing unit 300. The light source unit 100 includes a light source 11, a driver 111, a lens 12, a beam splitter 13, and a monitor light receiving element 14.

  The light source 11 can emit light (light beam) having a predetermined wavelength, and examples thereof include a semiconductor light emitting element. Moreover, what uses discharge etc. may be used. A light source that can emit stable light can be widely used. In this embodiment, a laser light emitting element (LD: Laser Diode) that emits laser light is employed.

  The light source 11 is controlled to be emitted by the processing unit 300. The light source 11 is driven to emit light with a drive signal (power) from the driver 111, and the driver 111 drives the light source 11 based on a control signal (light emission signal) from a light source control unit 311 (to be described later) of the processing unit 300. A drive signal for generating is generated. Thereby, the light emission timing, intensity, etc. of the light beam emitted from the light source 11 are adjusted.

  The light source 11 is a point light source, and the emitted light beam is divergent light. Therefore, the light source unit 100 transmits the light beam emitted from the light source 11 through the lens 12 and converts it into parallel light or substantially parallel light. The lens 12 is a collimator lens here, but is not limited to this, and an optical element that converts divergent light into parallel light can be widely used.

  The light beam emitted from the lens 12 enters the beam splitter 13. The beam splitter 13 is optimized for the light beam emitted from the light source 11, and reflects part of the incident light and transmits the rest. The light reflected by the beam splitter 13 enters the monitor light receiving element 14. The monitor light receiving element 14 transmits a monitor signal based on the incident light to the light source control unit 311.

  The light beam that has passed through the beam splitter 13 enters the optical scanning unit 200. As shown in FIGS. 2 and 3, the optical scanning unit 200 includes an optical scanning element 2, a driver 201, and a signal processing unit 202. The optical scanning element 2 will be described below with reference to the drawings. FIG. 4 is a schematic plan view of an optical scanning element provided with a piezoelectric actuator.

  The optical scanning element 2 has a minute structure called a MEMS (Micro Electro Mechanical System) mirror. In the following description, the optical scanning element 2 may be referred to as a MEMS mirror 2. The MEMS mirror 2 scans the light beam in a predetermined area (irradiation target area) by moving the reflection direction of the light beam from the light source unit 100 by swinging the mirror body 21 having the reflection surface 211.

  As shown in FIG. 4, the optical scanning element 2 includes a mirror body 21 (swinging portion), a pair of elastic support portions 22, an outer frame 23, and an actuator 24 (driving portion). The optical scanning element 2 is often molded by subjecting a single substrate to surface treatment. In this case, the mirror body 21, the elastic support portion 22, and the outer frame 23 are integrally formed. .

  The outer frame 23 has a rectangular frame shape having a through window 231 at the center. The outer frame 23 is fixed to a member whose movement is restricted with respect to the irradiation target area of the light beam such as a case (not shown) of the projection apparatus A. The mirror body 21 is rotatably supported via a pair of elastic support portions 22 protruding from the inner wall of the through window 231 of the outer frame 23.

  The pair of elastic support portions 22 are long members (plate-shaped members having a rectangular shape in plan view) having the same length. The elastic support portion 22 has one end connected to the inner surface of the through window 231 of the outer frame 23 and the other end connected to the mirror body 21. The optical scanning elements 2 are arranged so that the outer frame 23, the pair of elastic support portions 22 and the central axis C1 of the mirror body 21 coincide in plan view. The pair of elastic support portions 22 can be elastically twisted around the central axis C1, and the pair of elastic support portions 22 is elastically twisted, whereby the mirror body 21 rotates (swings) around the central axis C1. . The center axis C1 is also a swing center line C1. Therefore, in the following description, the swing center line C1 will be described instead of the center axis C1.

  The mirror body 21 is a square plate member, and one of the two main surfaces is a reflecting surface 211 that reflects the light beam from the light source unit 100. The reflecting surface 211 may be formed by forming a reflecting film on the surface of the mirror body 21 or may be a mirror-treated surface if the mirror body 21 itself is a material that reflects light. .

  The optical scanning element 2 includes an actuator 24 for swinging the mirror body 21. Examples of the actuator 24 include a piezoelectric actuator using a piezoelectric element such as PZT and PLZT, an electrostatic actuator using electrostatic force, and a magnetic actuator using a magnet and a coil. Here, a piezoelectric actuator is employed as the actuator 24. The actuator 24 is configured to bend when a voltage (drive signal) is applied to the piezoelectric element, and uses a force when the bend occurs.

  In order to rotate the mirror body 21 around the swing center line C1 with such an actuator 24, the actuator 24 sandwiches the swing center line C1 between both ends 232 of the outer frame 23 in the swing center line C1 direction. Are arranged so as to be symmetrical. That is, a total of four actuators 24 are arranged, two in each of the actuators 24 so as to be symmetrical with respect to each of the end portions 232 of the outer frame 23 with the oscillation center line C1 interposed therebetween. The actuator 24 is disposed on the surface of the end 232 of the outer frame 23, and a force acts on the end 232 when the actuator 24 is driven to bend. Then, by adjusting the magnitude (strength) and / or timing of the operation of the four actuators 24, reciprocation from the end portion 232 to the elastic support portion 22 in the rotation direction about the swing center line C1. A force that moves, that is, swings is applied. The elastic support portion 22 is elastically twisted by this force, and the mirror body 21 is swung around the swing center line C1 using the reaction force.

  Note that the optical scanning element 2 is provided with wiring (not shown) for supplying a voltage (drive signal) to the piezoelectric element of the actuator 24, and the wiring is connected to the driver 201. The driver 201 generates a driving signal for driving the actuator 24 based on a control signal (scanning signal) from the scanning control unit 312 described later, and supplies the driving signal to each actuator 24. Further, the signal processing unit 202 generates a displacement signal including information on the displacement (angle) of the reflecting surface 211 based on the sensor signal output from the optical scanning element 2, and transmits the displacement signal to the scanning control unit 312.

  Next, the processing unit 300 will be described. The processing unit 300 controls the light source unit 100 and the optical scanning unit 200.

  The processing unit 300 includes a calculation processing circuit such as a CPU and MPU, and includes a scanning light source control unit 31, a calculation processing unit 32, a drive signal generation unit 33, and an external connection unit 34 as shown in FIG. Yes.

  The scanning light source control unit 31 is a control unit that controls the emission control of the light beam from the light source unit 100, the scanning speed of the light beam by the optical scanning unit 200, the scanning angle (scanning range), and the like. The scanning light source control unit 31 includes a light source control unit 311 and a scanning control unit 312.

  The light source control unit 311 is a control circuit that controls driving of the light source unit 100. The light source control unit 311 receives a monitor signal from the monitor light receiving element 14. The light source control unit 311 generates a control signal for controlling the output of the light source 11 of the light source unit 100, the light output timing, the light output time, and the like based on the monitor signal and light output information described later, and transmits the control signal to the driver 111.

  The scanning control unit 312 is a control circuit that controls driving of the optical scanning unit 200. The scanning control unit 312 receives a displacement signal from the signal processing unit 202 of the optical scanning unit 200. Based on the displacement signal and operation information described later, a control signal for appropriately swinging the mirror body 21 is generated and transmitted to the driver 201.

  The light source control unit 311 and the scanning control unit 312 operate in synchronization. Accordingly, it is possible to scan with a light beam having a constant intensity, and by turning on / off the light beam while performing scanning, a diagram (one-line diagram) is irradiated with the spot of the light beam. Can also be generated.

  As described above, the projection apparatus A is often used like the exposure apparatus Lt of the image forming apparatus Pt. Information for scanning from the external device via the external connection unit 34 in order to perform control to receive an input signal from the external device and irradiate the light beam (for example, image data of one line of an image to be printed when used in an exposure apparatus) ) To get. Information acquired from the external device is sent to the arithmetic processing unit 32. The arithmetic processing unit 32 generates ON / OFF mapping data for one line based on the acquired information, and supplies the mapping data to the drive signal generation unit 33. The drive signal generation unit 33 generates light output information including the light output intensity and timing information of the light source unit 100 and scanning information including the swing angle and speed of the mirror body 21 of the optical scanning unit 200, and sends it to the scanning light source control unit 31. send.

  Further, the light source control unit 311 generates a control signal for controlling driving of the light source unit 100 based on the light emission information. The optical scanning control unit 312 generates a control signal for controlling driving of the optical scanning unit 200 based on the scanning information.

  Next, details of the optical scanning element according to the present invention will be described with reference to the drawings. FIG. 5 is a side view of the mirror shown in FIG. In FIG. 5, a part of the mirror body 21 and the elastic support portion 22 is illustrated.

  In the optical scanning element 2, the force of the actuator 24 is applied to the elastic support portion 22, and the elastic support portion 22 is twisted around the swing center line C <b> 1. And the elastic restoring force of the twist of the elastic support part 22 acts on the mirror body 21, and the mirror body 21 rock | fluctuates. At this time, since the axis of twist of the elastic support portion 22 becomes the swing center line C1, the swing center line C1 coincides with the central axis of the elastic support portion 22. Further, since the mirror body 21 swings due to the elastic restoring force of the torsion of the elastic support portion 22, the size of the elastic support portion 22 is determined by the weight, the swing frequency, and the deflection angle of the mirror body 21. Further, the mirror body 21 has a thickness such that the reflection surface 211 is not warped.

  Therefore, in the general optical scanning element 2, the thickness of the mirror body 21 and the elastic support portion 22 is often different as shown in FIG. The optical scanning element 2 is configured to swing the mirror body 21 and reflect light at the reflecting surface 211 of the mirror body 21, and the swing center line C <b> 1 is closer to the reflecting surface 211 than the central axis d <b> 1 of the mirror body 21. The elastic support part 22 is provided so that it may become close. This will be explained with reference to a new drawing.

  6A is a cross-sectional view showing a swinging state of the mirror shown in FIG. 5, and FIG. 6B is a cross-sectional view showing a cross-sectional shape of the mirror shown in FIG. 6A and 6B are cross-sectional views, but hatching is omitted.

  In FIG. 6A, the mirror body 21 when it swings around the central axis d1 (see FIG. 5) of the mirror body 21 is indicated by a broken line, and the mirror body 21 when it swings around the swing center line C1 is indicated by a solid line. Show. In FIG. 6A, the swing angle when swinging around the central axis d1 is the same as the swing angle when swinging around the swing center line C1. Further, the mirror body 21 has a different size between the reflecting surface 211 and the opposite surface 212, and details of the difference in size between the reflecting surface 211 and the opposite surface 212 will be described later.

  6A, the right end portion of the reflecting surface 211 is m1, the left end portion is m2, the right end portion of the opposite surface 212 of the shape of the present invention is n11, and the left end portion is n21. As shown in FIG. 6A, the normal line of the reflecting surface 211 intersecting with the oscillation center line C1 and the central axis d1 of the mirror body 21 (indicated by the normal line H1 or the normal line H2 in FIG. 6A) It differs depending on the position in the thickness direction of the center of. As shown in FIG. 6A, the intersection with the reflecting surface 211 of the normal line H1 passing through the swing center line C1 when swung around the swing center line C1 is the reflecting surface of the normal line H2 passing through the central axis d1. The amount of deviation from the center is smaller than the intersection with 211. That is, when viewed in the irradiation direction of the light beam, the amount of deviation of the reflecting surface 211 is smaller when swinging around the swing center line C1 close to the reflecting surface 211 than when swinging around the central axis d1.

  Assuming that an effective light beam irradiation range is a range irradiated with a light beam that does not deviate from the reflecting surface 211 during swinging, the effective light beam irradiation range is smaller as the deviation of the reflecting surface 211 is smaller when viewed from the irradiation direction of the light beam. Can be increased. That is, the spot shape (spot diameter) of the light beam can be increased by shifting the oscillation center line C1 toward the reflecting surface 211 with respect to the central axis d1 of the mirror body 21.

  For example, in FIG. 6A, when the mirror body 21 is swung in the clockwise S1 direction at the maximum angle, the reflecting surface 211 is shifted to the end m1 side as seen from the irradiation direction of the light beam. At this time, by making the cross-sectional shape of the light beam not to protrude from the end m2 side (diameter that does not protrude), the reflection surface 211 shifts to the end m2 side when the light beam swings to the opposite side. The beam does not protrude from the end m2 side of the reflecting surface 211. Similarly, when the light beam is swung in the counterclockwise S2 direction at the maximum angle, the cross-sectional shape of the light beam is set to a shape (diameter) that does not protrude from the end m1 side. By doing so, similarly, the light beam is unlikely to protrude from the end m1 side of the reflecting surface 211 when it is swung to the opposite side.

  From the above, the spot shape (spot diameter) of the light beam can be increased when the oscillation center line C1 of the mirror body 21 is closer to the reflecting surface 211. Therefore, the elastic support portion 22 is formed so as to shift the swing center line C1 toward the reflecting surface 211 with respect to the central axis d1 of the mirror body 21.

  Further, when the mirror body 21 swings about the swing center line C <b> 1, an atmospheric pressure difference is generated between the reflecting surface 211 of the mirror body 21 and the opposite surface 212, and the atmospheric pressure difference causes the mirror body 21 to swing. Affect. In the mirror body 21, in order to suppress this pressure difference, a pressure difference adjustment unit formed so that the reflecting surface 211 protrudes outward from the opposite surface 212 in the light irradiation direction (thickness direction of the mirror body 21) is provided. ing. This atmospheric pressure difference adjusting unit will be described below.

  As shown in FIG. 6B, when the mirror body 21 swings in the clockwise S1 direction, the air on the m2 side is compressed and the air on the m1 side is depressurized on the reflecting surface 211. Therefore, the atmospheric pressure on the end m2 side is increased, and the atmospheric pressure on the end m1 side is decreased. Similarly, on the opposite surface 212, the pressure on the end n21 side is low, and the pressure on the end n11 side is high. Further, when swinging in the reverse direction (counterclockwise S2), compression and decompression are reversed. That is, the atmospheric pressure on the end m1 side of the reflecting surface 211 is increased, and the atmospheric pressure on the end m2 side is decreased. Similarly, on the opposite surface 212, the atmospheric pressure on the end n21 side increases, and the atmospheric pressure on the end n11 side decreases. In this way, when the mirror body 21 is swung, fluctuations in atmospheric pressure occur on the surfaces of the reflecting surface 211 and the opposite surface 212.

  That is, when the atmospheric pressure on the end m1 side of the reflecting surface 211 becomes higher (lower), the atmospheric pressure on the end n11 side of the opposite surface 212 becomes lower (higher). Moreover, when the atmospheric pressure on the end m2 side becomes higher (lower), the atmospheric pressure on the end n21 side of the opposite surface 212 becomes lower (higher). That is, on the same side with respect to the swing center line C1 of the reflecting surface 211 and the opposite surface 212, when the pressure on one surface is high, the pressure on the other surface is low. Therefore, an atmospheric pressure difference (atmospheric pressure difference) is generated on the surface (the surface 212 opposite to the reflecting surface 211) of the mirror body 21 by swinging.

  In FIG. 6B, the shape of the present invention is indicated by a solid line, and the general shape is indicated by a two-dot chain line. In FIG. 6B, the same parts as those in FIG. 6A are denoted by the same reference numerals. Moreover, the right end part of the opposite surface 212 in a general shape is set to n12, and the left end part is set to n22. Here, the general-shaped mirror body 21 is a rectangular parallelepiped shape in which adjacent surfaces are perpendicular to each other.

  As described above, when the mirror 21 is swung, the air is pressed by the reflecting surface 211 and the opposite surface 212 to compress the air on the surface, and the air on the opposite side is decompressed to change the air pressure on the surface. There is a pressure difference due to fluctuations in pressure. The faster the tangential speed (linear velocity) of the swing of the reflecting surface 211 and the opposite surface 212 is, the more air is compressed / depressurized in a shorter time. That is, the higher the linear velocity of the reflecting surface 211 and the opposite surface 212 when the mirror body 21 is swung, the larger (higher or lower) the variation in the atmospheric pressure on the surface.

  As shown in FIG. 6B, in the case of an optical scanning element having a general cross-sectional shape (rectangular cross-sectional shape), assuming that the distance from the oscillation center line C1 to the end m1 or m2 of the reflecting surface 211 is r1, the opposite surface The distance r2 to the end n12 or n22 of 212 is longer than r1. When such a general-shaped mirror is swung, the length to the end portions (m1 and m2) of the reflecting surface is different from the end portion (n12 or n22) on the opposite surface. And the linear velocity at the time of swinging of the end of the opposite surface 212 are different.

  In the optical scanning element having a general-shaped mirror, the radius at the time of swinging of the end is different, so that the atmospheric pressure difference is increased in the vicinity of the end of the surface opposite to the surface of the reflecting surface. When the pressure difference between the reflecting surface and the opposite surface increases, the force due to the pressure difference (pressure difference) increases or decreases the elastic restoring force due to the torsion of the elastic support portion. For this reason, the swing angle and frequency of the mirror body are deviated and the timing of switching the operation is deviated, resulting in a response delay of the optical scanning element. Moreover, if the pressure difference between the surface of the reflecting surface and the surface opposite to the surface is large, the variation of the air pressure becomes large, and if the surrounding environment has high humidity, condensation tends to occur on the surface of the mirror. If condensation occurs on the reflecting surface or the opposite surface, the oscillation may become unstable or the light reflectance may be reduced.

  Therefore, in the optical scanning element 2 according to the present invention, the portion farthest from the swinging center line C1 on the side surface of the mirror body 21 (the portion surrounded by the ellipse Ar in FIG. 4) is used as the atmospheric pressure difference adjustment unit. Then, in the atmospheric pressure difference adjusting unit, as shown in FIG. 6A, the length from the swinging center line C1 to the ends n11 and n21 of the opposite surface 212 in the cutting plane orthogonal to the swinging center line C1 of the mirror body 21 is set. The length r1 is the same as the length to the ends m1 and m2 of the reflecting surface 211. That is, in the cross section cut by a plane orthogonal to the oscillation center line C 1, the mirror body 21 is centered on the oscillation center line C 1, a circle (arc) having a radius r 1, the ends m 1 and m 2 of the reflection surface 211, and the opposite surface. The ends n11 and n21 of 212 overlap.

  By making the end surface of the mirror body 21 (swinging part) with respect to the swinging center line as described above, the pressure difference between the front and back surfaces of the swinging part can be kept small. Further, it is possible to suppress dew condensation due to a pressure difference to the mirror body 21 when used in a high humidity environment, and to suppress a decrease in rocking accuracy due to a change in reflectance and a weight balance of the rocking part due to dew condensation. it can. Thereby, by reducing the influence of the pressure difference between the front surface and the back surface on the swinging of the swinging unit, the swinging accuracy (swinging angle, speed, switching timing) of the swinging unit is reduced. The response delay of the scanning light due to can be suppressed.

  In the present embodiment, the distance r1 from the oscillation center line C1 of the pressure difference adjustment unit of the mirror body 21 to the end m1 (m2) of the reflecting surface 211 and the distance r1 to the ends n11 and n21 on the opposite surface. Are the same length. By doing so, the effect of suppressing the pressure difference can be enhanced, but the distance is not necessarily the same. At least the outer peripheral surface portion of the mirror body 21 has a size such that the opposite surface 212 is hidden by the reflecting surface 211 when viewed in the thickness direction of the mirror body 21, and the atmospheric pressure difference adjusting portion has a reflecting surface that is thicker than the opposite surface. If it is the structure which protruded to the outer side in the direction orthogonal to, an atmospheric pressure difference and dew condensation can be suppressed.

  Further, in the atmospheric pressure difference adjusting portion of the mirror body 21, the side surface is inclined so as to narrow from the reflecting surface 211 side toward the opposite surface 212 side. Thereby, even if the mirror body 21 is swung, when the light beam from the light source unit 100 is incident, the side surface of the mirror body 21 is hardly irradiated. Thereby, generation | occurrence | production of the stray light which is the light which is reflected (scattered) by surfaces other than the reflective surface 211, and is irradiated to an irradiation object area | region can also be suppressed.

  In the present embodiment, the mirror body 21 is a flat plate member having a square shape in plan view, but is not limited thereto, and may be rectangular in plan view.

Second Embodiment
Another example of the optical scanning element according to the present invention will be described with reference to the drawings. FIG. 7 is a side view of a mirror body of the optical scanning element according to the present invention. The optical scanning element 2a of the present embodiment has the same configuration as the optical scanning element 2 of the first embodiment except that the shape of the end surface of the mirror body 21a is different. Therefore, substantially the same parts are denoted by the same reference numerals and detailed description thereof is omitted.

  As shown in FIG. 7, the mirror body 21 a is orthogonal to the central axis C <b> 1 like the mirror body 21, and the length of the line connecting the central axis C <b> 1 and the ends of the reflecting surface 211 and the opposite surface 212 is r <b> 1. And the pressure difference adjustment part of the mirror body 21a in the cross section of FIG. 7 becomes the circular arc 213 which made the length r1 the curvature radius. Since the mirror body 21a is a flat plate member extending in the direction of the swing center line C1, the atmospheric pressure difference adjusting portion of the mirror body 21a has a cylindrical shape with a radius of r1.

  Thus, by making the atmospheric pressure difference adjustment part of the mirror body 21a into a cylindrical shape, the surrounding air is less likely to be disturbed at the end face when swinging. In addition, it is possible to reduce the atmospheric pressure difference between the reflecting surface 211 and the opposite surface 212, and the mirror 21a is swung with high accuracy and dew condensation is suppressed, so that the scanning accuracy of the light beam to the irradiation target region is achieved. Can be suppressed.

  Other features are the same as in the first embodiment.

<Third Embodiment>
Another example of the optical scanning element according to the present invention will be described with reference to the drawings. 8 is an enlarged view of a mirror body of the optical scanning element according to the present invention, FIG. 9 is a cross-sectional view of the mirror body shown in FIG. 8 cut along line IX-IX, and FIG. 10 is a mirror shown in FIG. It is sectional drawing which cut | disconnected the body by the XX line. 9 and 10 are cross-sectional views, but hatching is omitted.

  As shown in FIG. 8, the mirror body 21b has a circular shape in plan view. The whole side part of the mirror body 21b is an atmospheric pressure difference adjustment part. That is, the side part of the mirror body 21b has a cross section cut at a plane orthogonal to the swinging center line C1 at all positions, and the end of the reflecting surface 211 and the end of the opposite surface 212 centered on the swinging center line C1. It has the shape arrange | positioned on the circular arc of the same diameter. The side surface of the mirror body 21b of the present embodiment is formed such that the cross-sectional shape cut by a plane orthogonal to the swing center line C1 forms an arc centered on the swing center line C1.

  For example, FIG. 9 is a cross-sectional view in which the end portion of the mirror body 21b is cut along a plane orthogonal to the swing center line C1 at a position farthest from the swing center line C1, and the reflection surface 211 is separated from the swing center line C1. Both the length to the end and the length from the oscillation center line C1 to the end of the opposite surface 212 are r11. At that position, the end surface of the mirror body 21b has a circumferential shape 214 having a radius r11.

  Further, as shown in FIG. 10, at the position where the end portion is displaced from the position farthest from the swing center line C1, the swing center line C1 of a cross section cut by a plane orthogonal to the swing center line C1 at that position. The length from the reflection surface 211 to the end of the reflecting surface 211 and the length from the opposite surface 212 to the end are both r12. At that position, the end surface of the mirror body 21b has a circumferential shape 215 having a radius r12.

  That is, when the distance from the swinging center line C1 to the end is different depending on the position of the end portion as in the mirror body 21b, each of the reflecting surface 211 and the opposite surface 212 is a plane that intersects the swinging center line C1. The distance to the end of the sway varies along the oscillation center line C1. Further, the end surface of the mirror body 21b has a circumferential shape having a curvature radius that is a length to a point that is orthogonal to the swing center line C1 and intersects with the end portions of the reflection surface 211 and the opposite surface 212.

  By making the length from the swing center line C1 to both ends of the reflecting surface 211 and the opposite surface 212 the same, the pressure difference between the reflecting surface 211 and the opposite surface 212 due to the swinging of the mirror body 21b is reduced. be able to. Further, since the end surface of the mirror body 21b is a curved surface having a radius of curvature with a length from the swing center line C1 to both ends of the reflecting surface 211 and the opposite surface 212, ambient air is disturbed during swinging. The mirror body 21b can be rocked with high accuracy.

  In this embodiment, the mirror body 21b has a flat plate shape (disc shape) in a plan view circle, but is not limited thereto. For example, a shape that is line-symmetric with respect to the swing center line and at least a part of the side portion is inclined with respect to the swing center line in plan view (for example, a triangle, a rhombus, a hexagon, etc. Polygons, ellipses, etc.).

  Other features are the same as in the first embodiment.

  In the present embodiment, the entire side surface of the mirror body 21b is the atmospheric pressure difference adjustment unit, but at least a part may be the atmospheric pressure difference adjustment unit. At this time, it is preferable that the atmospheric pressure difference adjusting portion is formed at a symmetrical position with respect to the oscillation center line C1. Note that the greater the linear velocity at the end of the mirror body 21b when swinging, the greater the pressure difference. Therefore, the air pressure difference adjustment unit includes the end portion farthest from the swinging center line C1 in the plan view of the mirror body 21b (that is, a line passing through the center of the reflecting surface 211 and orthogonal to the swinging center line C1 and the reflecting surface). 211 is preferably included).

  However, there may be a case where an end portion farthest from the swing center line C1 of the mirror body 21b in a plan view is not included in the atmospheric pressure difference adjustment unit due to manufacturing restrictions, attachment position restrictions, and the like. Even in this case, an atmospheric pressure difference is suppressed by the atmospheric pressure difference adjustment unit provided in a portion excluding the farthest end, and an effect of suppressing dew condensation can be obtained.

<Fourth embodiment>
Another example of the optical scanning element according to the present invention will be described with reference to the drawings. 11 is a side view of a mirror body of the optical scanning element according to the present invention, and FIG. 12 is a cross-sectional view of the mirror body shown in FIG. 11 cut along a plane orthogonal to the oscillation center line. The optical scanning element 2c has the same configuration as the optical scanning element 2 except that the positions of the mirror body 21c and the elastic support portion 22c are different. The substantially same parts are denoted by the same reference numerals, and detailed description of the same parts is omitted. The mirror body 21c and the elastic support portion 22c are different in relative attachment positions, but the shapes of the mirror body 21c and the elastic support portion 22c are the same as those of the mirror body 21 and the elastic support portion 22.

  As shown in FIG. 11, in the optical scanning element 2 c, a part (here, half) of the elastic support portion 22 c is shifted above the reflection surface 211 so that the center of the elastic support portion 22 c overlaps the reflection surface 211. It has a different shape. The elastic support portion 22c is provided so that the swing center line C11 overlaps the reflecting surface 211. That is, the length from the swing center line C11 to the end of the reflecting surface 211 and the end of the opposite surface 212 is a length r12 that is half the length in the direction orthogonal to the swing center line C11.

  In such a configuration, since the swing center line C11 and the reflection surface 211 are arranged on the same plane, the reflection surface 211 can be swung around the swing center line C11. As described above (see FIG. 6A and the like), the closer the swing center line C11 is to the reflecting surface 211, the smaller the deviation of the reflecting surface 211 seen from the light beam irradiation direction. Further, since the oscillation center line C11 and the reflection surface 211 are the same surface, the deviation of the reflection surface 211 at the time of oscillation can be eliminated, and the effective light beam irradiation range can be increased (maximized). It is. That is, the light beam shape (diameter) matched to the shape of the reflecting surface 211 can be maximized.

  Other features are the same as in the first embodiment.

<Fifth Embodiment>
Another example of the optical scanning element according to the present invention will be described with reference to the drawings. FIG. 13 is a sectional view of a mirror body of the optical scanning element according to the present invention. The mirror body 21d shown in FIG. 13 has the same configuration as that of the fourth embodiment except that the shape of the end surface formed at a position away from the swing center line C11 during swinging is substantially the same. Are denoted by the same reference numerals and detailed description of the same parts is omitted.

  As shown in FIG. 13, the mirror body 21d is formed with a plurality of truncated spherical recesses 216 (here, two, but not limited thereto). By forming the recess 216, the airflow flowing on the side surface of the mirror body 21d during oscillating is turbulent, and the separation from the object surface is suppressed. As a result, it is possible to suppress the mirror body 21d from being pulled in the direction opposite to the operation direction at the time of swinging from the airflow, and to swing accurately.

  Other features are the same as in the fourth embodiment.

  The optical scanning element described above has a configuration in which the light beam is scanned one line (one-dimensional) like the exposure apparatus Lt of FIG. As an optical scanning element, a light beam can be scanned two-dimensionally by combining these one-dimensional scanning configurations. Hereinafter, a projection apparatus using a light beam for performing two-dimensional scanning will be described with reference to the drawings. FIG. 14 is a schematic view of a projector using the projection apparatus according to the present invention.

  As shown in FIG. 14, the projection apparatus B used for the projector Pj includes a light source unit 100 and an optical scanning unit 400. The projection apparatus B reflects the light emitted from the light source unit 100 by a reflection surface 411 of a mirror body 41 (described later) provided in the light scanning unit 400, and causes the screen Sc that is an irradiation target region to be irradiated with the spot Spt of the light beam. Scan.

  For example, the light source unit 100 has a configuration capable of emitting light of three colors (three wavelengths) of RGB, and appropriately matches the light of each wavelength of RGB from the light source unit 100 to the optical scanning unit 400. Incident. The optical scanning unit 400 has a reflecting surface that swings around two intersecting (here, orthogonal) axes, and the oscillating reflecting surface allows light from the light source unit 100 to be incident in a timely manner. An image is formed on the screen Sc.

  An optical scanning element capable of scanning a light beam in two different axial directions will be described with reference to the drawings. FIG. 15 is a plan view of an optical scanning element according to the present invention.

  As shown in FIG. 15, the optical scanning element 4 swings the mirror body 41 having the reflection surface 411 around the first swing center line C21 and the second swing center line C22, so that the light beam is emitted. Scanning. The optical scanning element 4 includes a mirror body 41, a first elastic support portion 42, a swing support portion 43, a first actuator 44, a second elastic support portion 45, a second actuator 46, and a frame body 47. In FIG. 15, the vertical axis is the first swing center line C21 and the horizontal axis is the second swing center line C22.

  The mirror body 41 is a disk-shaped member having the same configuration as the mirror body 21, that is, a reflection surface 411 is formed. Both the front end portion of the first swing center line C21 and the first elastic support portion 42 are connected to the mirror body 41. That is, the mirror body 41 is connected to the center portion of the first elastic support portion 42. The first elastic member 42 is configured to be elastically twistable, and the mirror body 41 can swing around the first swing center line C21. In plan view, the second swing center line C22 orthogonal to the first swing center line C21 overlaps the center of the mirror body 41. The mirror body 41 and the first elastic support portion 42 are configured to be line symmetric with respect to the first swing center line C21 and the second swing center line C2.

  The swing support portion 43 is a plate-like member that extends to the first swing center line C21, and makes a pair with the mirror body 41 interposed therebetween, and with respect to the first swing center line C21 and the second swing center line C22. It is provided to be symmetrical. A first actuator 44 is provided at a portion where both ends of the swing support portion 43 are connected to the first elastic support portion 42. Four first actuators 44 are also provided so as to be symmetric with respect to the first swing center line C21 and the second swing center line C22.

  The first actuator 44 includes a piezoelectric material and deforms (bends) when electric power is supplied. By appropriately driving the four first actuators 44, a force in the torsional direction about the first swing center line C21 is applied to the first elastic support portion 42. The first elastic support portion 42 is twisted by this force, and the mirror body 41 is swung around the first swing center line C21 by the elastic restoring force.

  A second elastic support portion 45 extending along the second swing center line C22 is connected to the center portion of the swing support portion 43 on the outside. The frame body 47 is provided with a rectangular opening window at the center, and the distal end portion of the second elastic support portion 45 is connected to the inner surface of the opening window of the frame body 47. A second actuator 46 extending along the first swing center line C22 is provided at an intermediate portion of the second elastic support portion 45. The second actuator 46 extends to the opposite side with the second elastic support portion 45 interposed therebetween. The second actuator 46 is connected to the second elastic support portion 45 and the frame body 47. Four second actuators 46 are provided, and are provided to be symmetric with respect to the first swing center line C21 and the second swing center line C22.

  The second actuator 46 also uses the same piezoelectric material as the first actuator 44, and is deformed (bent) when electric power is supplied. By appropriately driving the four second actuators 46, a force in the torsional direction about the second swing center line C22 is applied to the second elastic support portion 45. The second elastic support portion 45 is twisted by this force, and the swing support portion 43 swings around the second swing center line C22 by the elastic restoring force. When swinging around the second swing center line C22, the mirror body 41, the first elastic support portion 42, the swing support portion 43, and the first actuator 44 rotate integrally. That is, in the case of swinging around the second swing center line C22, the mirror body 41, the first elastic support portion 42, the swing support portion 43, and the first actuator 44 are swing portions.

  The optical scanning element 4 has the above-described configuration, and the reflecting surface 411 of the mirror body 41 can be swung to the first swing center line C21 and the second swing center line C22. In the optical scanning element 4, the end portion of the mirror body 41 (region Ar1 in FIG. 15) and / or the end portion in the direction along the first swing center line C21 of the swing support portion 43 (region Ar2 in FIG. 15). The end face shape as described above is formed at the end of the portion. The end surface shape as described above is a shape in which the length from the end of the swinging portion on the reflecting surface side and the opposite surface side to the swing center line is equal.

  In this way, by forming the end faces of the respective portions as described above, the optical scanning element 4 can swing with high accuracy around two swinging center lines that intersect (orthogonal). Thereby, the light beam can be scanned accurately. Further, the area Ar <b> 1 is the vicinity of the first actuator 44. And dew condensation can be suppressed by forming area | region Ar1 as mentioned above. The piezoelectric element is a semiconductor element that is sensitive to moisture, and the lifetime of the optical scanning element 4 can be extended by suppressing condensation.

  Still another example of the optical scanning element according to the present invention will be described with reference to the drawings. FIG. 16 is a plan view of still another example of the optical scanning element according to the present invention.

  As shown in FIG. 16, the optical scanning element 5 swings the mirror 51 having the reflecting surface 511 around the first swing center line C21 and around the second swing center line C22, so that the light beam is emitted. Scanning. The optical scanning element 5 includes a mirror body 51, a first elastic support portion 52, a swing support portion 53, a first actuator 54, a second elastic support portion 55, a second actuator 56, and a frame body 57.

  In the optical scanning element 5, portions other than the first actuator 54 and the second actuator 56 have substantially the same configuration as the corresponding part of the optical scanning element 4. Therefore, in the following description, the first actuator 54 and the second actuator 56 will be described.

  Both the first actuator 54 and the second actuator 56 are electrostatic drive units. As shown in FIG. 16, in the first actuator 54, a plurality of electrostatic electrodes 541 extending in a direction orthogonal to the first swing center line C21 are arranged on the first elastic support portion 52 at regular intervals. On the other hand, a plurality of electrostatic electrodes 542 are provided inward from the inner surface of the opening window of the swing support portion 53. The electrostatic electrodes 541 and the electrostatic electrodes 542 are alternately arranged. By applying a voltage between the electrostatic electrode 541 and the electrostatic electrode 542, a force that twists around the first oscillation center line C21 is applied to the first elastic support portion 52 by an electrostatic force. Accordingly, the first elastic support portion 52 is twisted, and the mirror body 51 is swung around the first swing center line C21 by the elastic restoring force.

  The length of the tip of the electrostatic electrode 541 provided on the first elastic support portion 52 from the first swinging center line C21 between the end on the reflective surface side and the end on the opposite surface side is constant. Thereby, the atmospheric pressure difference of the electrostatic electrode 541 when the mirror 51 swings around the first swing center line C21 is reduced, and dew condensation is suppressed.

  Similarly, the length of the tip of the electrostatic electrode 561 provided on the swing support portion 53 from the second swing center line C22 between the end on the reflection surface side and the end on the opposite surface side is constant. . Thereby, the atmospheric pressure difference of the electrostatic electrode 561 when the swing support part 53 swings around the second swing center line C22 is reduced, and dew condensation is suppressed.

  In each of the embodiments described above, the exposure apparatus of the image forming apparatus and the projector are exemplified as the apparatus using the optical scanning element and the projection apparatus according to the present invention. However, the present invention is not limited to this. The one-dimensionally scanning light beam can be used as an optical scanner such as a barcode reader or a distance measuring sensor. In addition, as a device that scans a light beam in two dimensions, it can be used as an optical scanner for detecting an indicator of an operation input device that performs an operation input of an apparatus with an aerial image, for example. In addition to these, it can be widely applied to apparatuses that scan a light beam in one or two dimensions.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this content. The embodiments of the present invention can be variously modified without departing from the spirit of the invention. Further, the above embodiments can be implemented in combination as appropriate.

A, B Projection device 100 Light source 11 Light source (LD)
DESCRIPTION OF SYMBOLS 111 Driver 12 Lens 13 Beam splitter 14 Monitor light receiving element 200 Optical scanning part 2 Optical scanning element 21 Mirror body 211 Reflecting surface 212 Opposite surface 22 Elastic support part 23 Outer frame 231 Opening window 24 Actuator 201 Driver 202 Signal processing part 300 Processing part 31 Scanning Light Source Control Unit 311 Light Source Control Unit 312 Scanning Control Unit 32 Arithmetic Processing Unit 33 Drive Signal Generation Unit 34 External Connection Unit 400 Optical Scanning Unit 41 Mirror Body 411 Reflecting Surface 42 First Elastic Support Unit 43 Swing Support Unit 44 First Actuator 45 Second elastic support portion 46 Second actuator 47 Frame 500 Optical scanning portion 51 Mirror body 511 Reflecting surface 52 First elastic support portion 53 Swing support portion 54 First actuator 541 Electrostatic electrode 542 Electrostatic electrode 55 Second Elastic support portion 56 Second actuator 561 Electrostatic electrode 562 Electrostatic electrode 57 Body Pt image forming apparatus Pc photoreceptor Ef charging unit Lt exposure apparatus Dp developing unit Tr transfer roller CL cleaning part Re discharger

Claims (8)

A flat rocking portion including a reflection surface that reflects light from the light source and an opposite surface;
The oscillating portion is oscillated around an oscillation center line shifted from the center in the thickness direction to the reflecting surface side,
The swinging portion is formed so that the opposite surface is hidden by the reflection surface when viewed in the thickness direction, and the reflection surface is orthogonal to the thickness direction at least in part of the outer peripheral surface portion than the opposite surface. An optical scanning element provided with an atmospheric pressure difference adjustment unit that protrudes outward in the direction in which it is performed.   2. The light according to claim 1, wherein the pressure difference adjusting unit of the swing unit has the same distance from the swing center line to the outer peripheral edge of the reflecting surface and the outer peripheral edge of the opposite surface. Scanning element.   The pressure difference adjusting unit of the swing unit includes at least a portion farthest from the swing center line of the swing unit when the swing unit is viewed in the thickness direction. 3. The optical scanning element according to 2.   In the atmospheric pressure difference adjustment unit of the swing unit, a shape cut by a plane orthogonal to the swing center line of a surface adjacent to the reflection surface and the opposite surface is an arc centered on the swing center line. The optical scanning element according to any one of claims 1 to 3.   5. The optical scanning element according to claim 1, wherein the oscillating portion has a shape in which the oscillating center line and the reflecting surface overlap each other.   6. The optical scanning element according to claim 1, wherein a portion of the side surface of the oscillating portion corresponding to the pressure difference adjusting portion has a shape including a plurality of concave portions.   The optical scanning element according to claim 1, wherein the oscillating portion is a circle when viewed in the thickness direction. A light source;
An optical scanning element according to any one of claims 1 to 7,
A drive unit provided in the optical scanning element to drive the swing unit;
And a processing unit that generates a driving signal for driving the driving unit.

Images