JP2012132976A - Image forming device and method for driving the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for driving an image forming device capable of reducing a circuit scale by facilitating control for preventing the trapezoidal distortion of an image.SOLUTION: A method for driving an image forming device for forming an image on a projection surface 21 by reflecting light on a reflection surface comprises a first driving step of driving the reflection surface for scanning a first direction and a second driving step of driving a reflection surface for scanning a second direction. In the first driving step, the driving of the reflection surface for scanning the first direction includes a driving period for providing drive force from the outside to the reflection surface and an inertia driving period for scanning without providing drive force to the reflection surface and controls whether or not drive force is provided to the reflection surface.

Description

  The present invention relates to an image forming apparatus and a driving method of the image forming apparatus.

  2. Description of the Related Art A type of scan projector that draws using two mirrors, a horizontal scanning mirror that uses resonance and a vertical scanning mirror such as a galvano mirror, is widely used. The projection surface is irradiated with light emitted from the light emitting unit. Then, scanning is performed in the horizontal direction and the vertical direction. Horizontal scanning is referred to as horizontal scanning or main scanning, and vertical scanning is referred to as vertical scanning or sub-scanning. The scanning speed of vertical scanning is slower than the scanning speed of horizontal scanning. The scan projector scans two-dimensionally by horizontal scanning and vertical scanning, and draws an image on the projection surface. Usually, the deflection angle around the rotation center axis of the horizontal scanning mirror is a constant angle.

  When such a scan projector draws an image on the projection surface, a distortion called “trapezoidal distortion” occurs, and correction is necessary. The trapezoidal distortion is a distortion in which the horizontal length is different between the upper side and the lower side of the image drawn on the projection plane. Trapezoidal distortion is caused by the fact that the optical path difference from the mirror to the projection plane differs depending on the location of the image. This also occurs when light is projected from a direction orthogonal to the projection surface, but is more noticeable when light is projected from a direction oblique to the direction orthogonal to the projection surface.

  A scan projector that corrects distortion is disclosed in Patent Document 1. According to this, the deflection angle around the rotation center axis of the horizontal scanning mirror is made variable and gradually changed. As a result, the width of the image changes. When scanning light on the projection surface, the trapezoidal distortion of the image is prevented by reducing the deflection angle of the horizontal scanning mirror as the position of the light in the vertical direction on the projection surface is farther from the scan projector. .

  Further, since the driving frequency of the horizontal scanning mirror is high, an energy efficient resonance driving type is usually used as the horizontal scanning mirror.

JP 2007-199251 A

  When correcting the trapezoidal distortion by the scan projector, it is necessary to control the deflection angle of the horizontal scanning mirror so that the deflection angle of the horizontal scanning mirror becomes the target deflection angle corresponding to the drawing line in the vertical scanning direction. Since the deflection angle control is performed every horizontal scanning line or every several lines, the control is complicated. Therefore, there has been a demand for a driving method of an image forming apparatus that can easily perform control of scanning light to form an image.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
The driving method of the image forming apparatus according to this application example is a driving method of the image forming apparatus that reflects light on the reflecting surface to form an image on the projection surface, and rotates the reflecting surface in the first direction. A first driving step of scanning light, and a second driving step of scanning the light in a second direction that intersects the first direction by rotating the reflection surface, and the reflection surface is connected to a spring. The first driving step applies a driving force to rotate the reflecting surface and accumulate energy in the spring, and an inertia driving period to rotate the reflecting surface using the restoring force of the spring; It is characterized by having.

  According to this image forming apparatus driving method, in the first driving step, the reflecting surface is rotated to scan light in the first direction. Then, in the second driving process, the reflecting surface is rotated to scan light in the second direction intersecting the first direction. Thus, an image can be formed by scanning light in two directions.

  The first driving process has a driving period and an inertia driving period. During the driving period, the driving force is applied to rotate the reflecting surface and store energy in the spring. In the inertia driving period, the reflecting surface is rotated using the restoring force of the spring. Therefore, energy can be accumulated in the spring by applying a driving force to the reflecting surface at a predetermined interval and rotating the reflecting surface, and light can be scanned using the restoring force of the spring. As a result, the light scanning control can be easily performed.

[Application Example 2]
In the driving method of the image forming apparatus according to the application example, the driving force is applied in the same direction as the direction in which the reflecting surface rotates during the driving period.

  According to this application example, the driving force is applied in accordance with the rotation direction of the reflecting surface. Therefore, the reflecting surface can be efficiently rotated as compared with the case where the driving force is applied in a direction different from the rotation direction.

[Application Example 3]
In the image forming apparatus driving method according to the application example, the driving period is performed in a vertical blanking period in which drawing is not performed.

  According to this application example, the driving force is applied when drawing is not performed within the vertical blanking period. When a driving force is applied to the reflecting surface, the rotational speed of the reflecting surface changes abruptly, so that the speed of scanning light changes abruptly. If the drawing is performed when the scanning speed of the light changes rapidly, the image is disturbed. In this application example, since the driving force is applied to the reflecting surface without affecting the drawing, it is possible to draw a high-quality image.

[Application Example 4]
In the driving method of the image forming apparatus according to the application example, the driving force is applied once in one driving period.

  According to this application example, the driving force is applied only once in one driving period. Therefore, it is possible to easily apply the driving force as compared with the method in which the driving force is applied a plurality of times in one driving period. As a result, the circuit for controlling the application of the driving force can be simplified.

[Application Example 5]
In the driving method of the image forming apparatus according to the application example, the driving force is applied so that a range of light scanning in the first direction is larger than a range of the image.

  According to this application example, the driving force is applied so that the range of light scanning in the first direction is larger than the range of the image. Therefore, drawing can be reliably performed in the first direction.

[Application Example 6]
An image forming apparatus according to this application example is an image forming apparatus that scans light with respect to a projection surface to form an image. The image forming apparatus emits light and reflects light emitted from the emitting section. A second reflecting surface that is movably provided, and that scans in the first direction relative to the projection surface and intersects the first direction at a scanning speed slower than a scanning speed for scanning in the first direction; An optical scanning unit that scans in the direction; and a drive control unit that controls the optical scanning unit, wherein the drive control unit scans the reflective surface in the first direction; and An angle detection unit that detects an angle in a second direction, and the driving unit applies a driving force to the reflection surface according to the angle detected by the angle detection unit and rotates the reflection surface. Store energy in the spring and use the restoring force of the spring And wherein the rotating the reflective surface.

  According to this application example, the emission unit emits light. The optical scanning unit has a reflecting surface, and the emitted light irradiates the reflecting surface. The light reflected from the reflecting surface irradiates the projection surface. The reflecting surface rotates to scan light in the first direction and the second direction. The first direction and the second direction intersect each other, and the scanning light forms an image. The drive control unit controls the optical scanning unit to scan light in the second direction at a scanning speed slower than the scanning speed for scanning in the first direction.

  The drive control unit has a drive unit and an angle detection unit. The angle detection unit detects an angle of the reflection surface in the second direction. Then, the driving unit applies a driving force to the reflecting surface according to the detected angle of the reflecting surface to rotate the reflecting surface and accumulate energy in the spring. And the reflective surface is rotated using the restoring force of a spring. As a result, the energy of the spring is consumed and rotational energy is accumulated on the reflecting surface. Then, the exchange of the spring energy and the rotational energy of the reflecting surface is repeated. Each time this replacement is performed, the reflection surface switches the rotation direction, so that the light reflected from the reflection surface scans the projection surface.

  Therefore, in this application example, the driving unit applies a driving force to the reflecting surface according to the angle of the reflecting surface in the second direction, thereby controlling the rotation of the reflecting surface so that the light scans in the first direction. Yes. That is, it is possible to perform a control of scanning light by a control in which the driving unit applies a driving force. As a result, the light scanning control is simplified, so that an image can be formed with simple control.

1 is a schematic perspective view illustrating a configuration of an image forming apparatus according to a first embodiment. 1 is a block diagram illustrating a configuration of an image forming apparatus. The schematic perspective view which shows the structure of an actuator. The schematic cross section for demonstrating the drive of an actuator. The block diagram which shows the structure of a galvanometer mirror. The block diagram which shows the structure of an operation control apparatus. FIG. 6 is a schematic diagram for explaining the operation of the image forming apparatus. The graph which shows transition of the deflection angle of an actuator. The graph which shows transition of the drive signal which drives a movable plate. The graph which shows transition of rotation of a movable plate, and a drive signal. The graph which shows a time-dependent change of the deflection angle of a movable plate. The graph which shows the time-dependent change of the mirror angle of a galvanometer mirror.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the drawings. In addition, each member in each drawing is illustrated with a different scale for each member in order to make the size recognizable on each drawing.

(First embodiment)
In this embodiment, an example of an image forming apparatus and a characteristic driving method of the image forming apparatus will be described with reference to FIGS.

  FIG. 1 is a schematic perspective view showing the configuration of the image forming apparatus. As shown in FIG. 1, the image forming apparatus 1 is placed on a support base 2 such as a desk. When the surface on which the image forming apparatus 1 is placed on the support base 2 is used as the projection surface 21, the image forming apparatus 1 scans light on the projection surface 21 to form an image. In other words, the image forming apparatus 1 projects an image by projecting onto the projection surface 21. That is, the projection surface 21 is used as a screen, and a predetermined image such as a still image or a moving image is drawn by scanning the projection surface 21 with light from the image forming apparatus 1. The image forming apparatus 1 is used by being placed on the projection surface 21 of the support 2. As a result, the positional relationship between the image forming apparatus 1 and the drawing area 142 that is an area drawn on the projection surface 21 is maintained in a predetermined positional relationship.

  In the drawing area 142, the direction in which the light moves on the projection surface 21 when changing the depression angle formed by the light emitted from the image forming apparatus 1 and the projection surface 21 is a vertical direction 21 b as a second direction, and the vertical direction 21 b The orthogonal direction is defined as a horizontal direction 21a as the first direction. The horizontal direction 21a and the vertical direction 21b are directions in which the image forming apparatus 1 scans light.

  FIG. 2 is a block diagram illustrating the configuration of the image forming apparatus. As shown in FIG. 2, the image forming apparatus 1 includes a light source unit 4 as an emission unit, an optical scanning unit 5, and an operation control device 8 as a drive control unit. The light source unit 4 is a device that emits light. The light scanning unit 5 is a device that scans and projects the light emitted from the light source unit 4 onto the projection surface 21. The operation control device 8 is a device that controls the operations of the light source unit 4 and the optical scanning unit 5.

  The light source unit 4 includes a red laser light source 41r that emits red laser light 44r, a green laser light source 41g that emits green laser light 44g, and a blue laser light source 41b that emits blue laser light 44b. The light source unit 4 is connected to the operation control device 8. The red laser light source 41r, the green laser light source 41g, and the blue laser light source 41b emit laser light 44 that is modulated in accordance with the drive signal output from the operation control device 8.

  The red laser light 44r emitted from the red laser light source 41r irradiates the optical scanning unit 5 after passing through the collimator lens 42r and the dichroic mirror 43r. Similarly, the green laser light 44g emitted from the green laser light source 41g irradiates the light scanning unit 5 after passing through the collimator lens 42g, the dichroic mirror 43g, and the dichroic mirror 43r. The blue laser light 44b emitted from the blue laser light source 41b irradiates the light scanning unit 5 after passing through the collimator lens 42b, the dichroic mirror 43b, the dichroic mirror 43g, and the dichroic mirror 43r.

  The collimator lenses 42r, 42g, and 42b are optical elements that make the laser beam 44 parallel light. Then, the dichroic mirrors 43r, 43g, and 43b combine the laser beams 44 of the respective colors using a built-in half mirror and emit them as one light beam. Thereby, the light source unit 4 can emit the light beam of the laser light 44 having the color tone and the brightness indicated by the operation control device 8 to the optical scanning unit 5.

  Next, the optical scanning unit 5 will be described. The optical scanning unit 5 includes an actuator 51. The actuator 51 has a movable plate 511a having a light reflecting portion 511e as a reflecting surface on one surface. And the laser beam 44 which the light source unit 4 injects changes the advancing direction by irradiating and reflecting the light reflection part 511e. Then, the laser light 44 reflected by the light reflecting portion 511 e irradiates the galvano mirror 12. The galvano mirror 12 has a mirror 121, and the laser beam 44 that irradiates the galvano mirror 12 is reflected by the mirror 121. Subsequently, the laser beam 44 reflected by the mirror 121 irradiates the projection surface 21.

  The movable plate 511a is rotatable about a rotation center axis 518 as a center axis. When the movable plate 511a rotates, the laser beam 44 emitted from the light scanning unit 5 scans in the horizontal direction 21a with respect to the projection surface 21. Similarly, the mirror 121 is rotatable about the rotation center axis 125 as a center axis. When the mirror 121 rotates, the laser beam 44 emitted from the light scanning unit 5 scans in the vertical direction 21 b with respect to the projection surface 21.

  The scanning speed at which the galvanometer mirror 12 scans in the vertical direction 21b is slower than the scanning speed at which the actuator 51 scans in the horizontal direction 21a. Thereby, the optical scanning part 5 scans the laser beam 44 two-dimensionally.

  The optical scanning unit 5 includes an angle detection unit 52 that detects the rotation angle of the actuator 51. The angle detection unit 52 detects the rotation angle of the movable plate 511a and outputs it to the operation control device 8. Further, the optical scanning unit 5 includes an angle detection unit 13 that detects the rotation angle of the mirror 121. The angle detection unit 13 detects the rotation angle of the mirror 121 and outputs it to the operation control device 8. The operation control device 8 can detect the location where the laser light 44 irradiates the projection surface 21 from the angle between the movable plate 511 a output from the optical scanning unit 5 and the mirror 121.

  The rotation center axis 518 of the actuator 51 and the rotation center axis 125 of the galvanometer mirror 12 are installed orthogonally. By providing the actuator 51 and the galvanometer mirror 12 in this way, it is possible to scan the laser light 44 emitted to the projection surface 21 in two directions that are two-dimensionally orthogonal. Thereby, a two-dimensional image can be drawn on the projection surface 21 with a relatively simple configuration.

  The laser light 44 emitted from the light source unit 4 is reflected by the reflecting surface of the light reflecting portion 511e of the actuator 51. Next, the laser beam 44 is reflected by the reflecting surface of the mirror 121 of the galvanometer mirror 12 and then irradiated on the projection surface 21 of the support 2. Then, the operation control device 8 rotates the light reflecting portion 511e and rotates the mirror 121 at an angular velocity slower than the angular velocity. Thereby, the laser beam 44 is scanned in the horizontal direction 21a with respect to the projection surface 21 and is scanned in the vertical direction 21b at a scanning speed slower than the scanning speed in the horizontal direction 21a. The laser beam 44 is scanned two-dimensionally with respect to the projection surface 21, and an image is drawn on the projection surface 21.

FIG. 3 is a schematic perspective view showing the structure of the actuator. As shown in FIG. 3, the actuator 51 includes a rectangular counter substrate 513. The material of the counter substrate 513 is not particularly limited as long as it has mechanical strength. For example, various glasses, silicon, SiO _{2 and the} like can be used. A rectangular frame-shaped spacer member 512 is provided so as to overlap with the counter substrate 513, and a base body 511 is provided so as to overlap with the spacer member 512.

The base 511 includes a frame-shaped support portion 511 b, and the support portion 511 b is disposed so as to overlap the spacer member 512. The upper surface of the spacer member 512 is joined to the lower surface of the base 511. The spacer member 512 is substantially equal to the shape of the support portion 511b in the plan view of the movable plate 511a. Such a spacer member 512 is made of, for example, various glasses, various ceramics, silicon, SiO ₂ or the like.

  In addition, it does not specifically limit as a joining method of the spacer member 512 and the base | substrate 511, For example, you may join via another members, such as an adhesive agent. In addition, anodic bonding or the like may be used as a bonding method depending on the constituent material of the spacer member 512 or the like.

  A movable plate 511a is disposed at the center of the base 511, and the movable plate 511a and the support portion 511b are connected by a connecting portion 511c as a spring and a connecting portion 511d as a spring. The connecting portion 511c is located on the left side of the movable plate 511a in the drawing, and the connecting portion 511d is located on the right side of the movable plate 511a in the drawing.

  The connecting portion 511c and the connecting portion 511d are made of an elastic body formed in a columnar shape, and are arranged along the rotation center axis 518. When a force is applied so that the movable plate 511a rotates about the rotation center axis 518, the movable plate 511a rotates by twisting the connecting portion 511c and the connecting portion 511d. At this time, since the connecting portion 511c and the connecting portion 511d act as springs, energy for rotating the movable plate 511a is accumulated in the connecting portion 511c and the connecting portion 511d.

  The material of the base 511 is not particularly limited as long as it is an elastic body having mechanical strength. Various materials such as silicon and metal can be used. In the present embodiment, for example, the base 511 is made of silicon as a main material. The movable plate 511a, the support portion 511b, and the connecting portions 511c and 511d are integrally formed. By using silicon as a main material, it is possible to realize excellent rotation characteristics and to exhibit excellent durability. In addition, silicon can be finely processed, and the actuator 51 can be formed in a small size.

  The movable plate 511a is substantially rectangular in plan view. A light reflecting portion 511e having light reflectivity is provided on the surface of the movable plate 511a opposite to the counter substrate 513. The surface of the light reflecting portion 511 e is a reflecting surface that reflects the laser light 44. The material of the light reflection part 511e should just reflect light, and is not specifically limited. For example, a metal film such as Al or Ni can be used. A rectangular parallelepiped permanent magnet 514 is provided on the surface of the movable plate 511a on the counter substrate 513 side.

  The permanent magnet 514 is magnetized in a direction orthogonal to the rotation center axis 518 in a plan view of the movable plate 511a. Specifically, the permanent magnet 514 is magnetized so that a line segment connecting both the S pole and the N pole of the permanent magnet 514 is orthogonal to the rotation center axis 518. In the present embodiment, the upper left side of the rotation center shaft 518 in the figure is the N pole, and the lower right side in the figure is the S pole. The material of the permanent magnet 514 is not particularly limited as long as it is a material having magnetism by magnetization. For example, a neodymium magnet, a ferrite magnet, a samarium cobalt magnet, an alnico magnet, or the like can be used.

  In the counter substrate 513, a coil 515 is provided on the surface on the permanent magnet 514 side at a location facing the movable plate 511a. The coil 515 is provided so as to surround the outer periphery of the permanent magnet 514 in a plan view of the movable plate 511a.

  Next, the angle detector 52 that detects the angle of the movable plate 511a of the actuator 51 will be described. A piezoelectric element 521 is installed on the connecting portion 511 c of the actuator 51. An electromotive force detection unit 522 is connected to the piezoelectric element 521, and the electromotive force detection unit 522 detects an electromotive force generated by the piezoelectric element 521. An angle detection unit 523 is connected to the electromotive force detection unit 522, and the angle detection unit 523 calculates the angle of the movable plate 511a based on the detection result of the electromotive force detection unit 522. The angle detection unit 52 is configured by the piezoelectric element 521, the electromotive force detection unit 522, and the angle detection unit 523.

  When the connecting portion 511c is torsionally deformed with the rotation of the movable plate 511a, the piezoelectric element 521 is deformed with the deformation of the connecting portion 511c. When the piezoelectric element 521 is deformed, it has a property of generating an electromotive force having a magnitude corresponding to a deformation amount with respect to a natural state to which no external force is applied. Then, the electromotive force detection unit 522 detects the electromotive force generated in the piezoelectric element 521 and outputs it to the angle detection unit 523. The angle detection unit 523 calculates the degree of torsion of the coupling unit 511c based on the magnitude of the electromotive force of the piezoelectric element 521. Further, the angle detection unit 523 obtains a deflection angle about the rotation center axis 518 of the movable plate 511a from the degree of twist. Then, a signal including information on the angle and deflection angle of the movable plate 511 a is transmitted from the angle detection unit 523 to the operation control device 8.

  The state where the drive signal is not supplied to the coil 515 is defined as the initial state of the actuator 51. At this time, the angle formed by the movable plate 511a and the support portion 511b is 0 °, and the state where the angle is 0 ° is used as a reference. Note that the angle of the movable plate 511a is an angle when the movable plate 511a rotates in a predetermined direction when the initial state of the actuator 51 is used as a reference. That is, the angle of the movable plate 511a to be detected is an angle formed between the light reflecting portion 511e when the actuator 51 is in the initial state and the light reflecting portion 511e when the movable plate 511a is rotated in a predetermined direction.

  Further, the detection of the angle of the movable plate 511a may be performed continuously in real time or may be performed intermittently. Moreover, the angle detection part 52 should just be able to detect the angle of the movable plate 511a, and is not limited to the method using a piezoelectric element.

  FIG. 4 is a schematic cross-sectional view for explaining the driving of the actuator. As shown in FIG. 4A, the actuator 51 has energization means 516 that supplies current to the coil 515. The energizing means 516 is an electric circuit, and supplies currents of various conditions such as the magnitude of the current value and the frequency to the coil 515. The energizing means 516, the coil 515, the permanent magnet 514, and the like constitute a drive unit 517 that rotates the movable plate 511a.

  The energization means 516 is connected to the operation control device 8. A predetermined drive signal is output from the operation control device 8 to the energizing unit 516, and a current corresponding to the drive signal is supplied from the energizing unit 516 to the coil 515. Specifically, the energization means 516 supplies an alternating current to the coil 515 under the control of the operation control device 8. An alternating current flows through the coil 515, and a magnetic field is generated in the thickness direction of the movable plate 511a. The operation control device 8 outputs a drive signal so as to periodically switch the direction of the magnetic field. A state in which the permanent magnet 514 side of the coil 515 is the S pole and the opposite side of the coil 515 to the permanent magnet 514 side is the N pole is a first state. The state where the permanent magnet 514 side of the coil 515 is the N pole and the opposite side of the coil 515 to the permanent magnet 514 side is the S pole is the second state. By switching the drive signal output from the operation control device 8, the coil 515 is switched alternately between the first state and the second state.

  In the first state, when the coil 515 is energized, the permanent magnet 514 side of the coil 515 becomes the south pole. As a result, a repulsive force is generated between the magnetic field generated in the coil 515 and the south pole side of the permanent magnet 514, and the south pole of the permanent magnet 514 is displaced away from the coil 515. At the same time, an attractive force is generated between the magnetic field generated in the coil 515 and the N pole side of the permanent magnet 514, and the N pole of the permanent magnet 514 is displaced in a direction approaching the coil 515. Thereby, the movable plate 511a rotates counterclockwise and tilts.

  As shown in FIG. 4B, in the second state, the permanent magnet 514 side of the coil 515 becomes an N pole by energizing the coil 515. As a result, a repulsive force is generated between the magnetic field generated in the coil 515 and the N pole side of the permanent magnet 514, and the N pole of the permanent magnet 514 is displaced away from the coil 515. At the same time, an attractive force is generated between the magnetic field generated in the coil 515 and the south pole side of the permanent magnet 514, and the south pole of the permanent magnet 514 is displaced in a direction approaching the coil 515. As a result, the movable plate 511a rotates clockwise and tilts.

  By alternately repeating the first state and the second state, the movable plate 511a is alternately rotated clockwise and counterclockwise about the rotation center axis 518. When the movable plate 511a rotates, the connecting portions 511c and 511d undergo torsional deformation. The operation control device 8 outputs a drive signal having a predetermined magnitude and a predetermined frequency to the energization means 516. Thereby, the operation control apparatus 8 can drive the movable plate 511a to resonance.

  The operation control device 8 controls a drive signal supplied to the coil 515 by the energization means 516. Thereby, the deflection angle of the movable plate 511a can be adjusted. Therefore, the energizing means 516 and the operation control device 8 constitute the main part of the adjusting means for adjusting the deflection angle of the movable plate 511a. This adjusting means adjusts the deflection angle of the movable plate 511a according to the angle of the mirror 121 of the galvanometer mirror 12. Therefore, the reflecting surface of the light reflecting portion 511 e operates according to the angle of the galvanometer mirror 12.

  The deflection angle of the movable plate 511a indicates the maximum angle when the movable plate 511a rotates in a predetermined direction when the initial state of the actuator 51 is used as a reference. That is, the deflection angle is an angle formed between the light reflecting portion 511e when the actuator 51 is in the initial state and the light reflecting portion 511e when the movable plate 511a is rotated to the maximum in a predetermined direction.

  FIG. 5 is a block diagram showing the configuration of the galvanometer mirror. As shown in FIG. 5, the galvanometer mirror 12 includes a mirror 121 that reflects light on the reflecting surface. The mirror 121 is provided so as to be rotatable about a rotation center shaft 125, and a motor 122 that rotates the mirror 121 is connected to the rotation center shaft 125. The motor 122 is connected to the drive circuit 123, and the drive circuit 123 supplies electric power that rotates the motor 122. Then, the motor 122 repeats forward rotation and reverse rotation alternately by the output of the drive circuit 123. As a result, the mirror 121 rotates about the rotation center axis 125. A drive unit 124 is configured by the motor 122, the drive circuit 123, and the like.

  Next, the angle detector 13 that detects the angle of the mirror 121 of the galvanometer mirror 12 will be described. The angle detection unit 13 includes an encoder 131 and an angle detection unit 132. The encoder 131 is provided in the galvanometer mirror 12 and outputs a signal corresponding to the change in the angle of the mirror 121. The angle detector 132 is connected to the encoder 131 and receives a signal output from the encoder 131. Then, the angle detector 132 calculates the angle of the mirror 121 based on the information included in the signal.

  When the mirror 121 is rotated by the operation of the driving unit 124, a signal corresponding to the rotation is transmitted from the encoder 131 to the angle detection unit 132. The angle detector 132 calculates the angle of the mirror 121 based on information included in the signal transmitted from the encoder 131. Next, the angle detection unit 132 transmits a signal including information on the angle of the mirror 121 to the operation control device 8.

  The reference in the angle of the mirror 121 is not particularly limited. The angle when the galvano mirror 12 is in a predetermined angle state may be set as a reference. Further, the angle detection of the mirror 121 may be performed continuously or intermittently. Moreover, the structure of the angle detection part 13 should just be able to detect the angle of the mirror 121, and is not specifically limited. You may employ | adopt the method of using other than an encoder.

  FIG. 6 is a block diagram showing the configuration of the operation control device. As shown in FIG. 6, the image forming apparatus 1 includes an operation control device 8, and the operation control device 8 is connected to the light source unit 4 and the optical scanning unit 5. The operation control device 8 includes a video data storage unit 81, a video data calculation unit 82, a drawing timing generation unit 83, a light source modulation unit 84, a drive signal instruction unit 85, and an angle instruction unit 86.

  The video data storage unit 81 is a concept including a semiconductor memory such as a RAM and a ROM, and an external storage device such as a hard disk and a CD-ROM. Functionally, a storage area is set for storing program software in which the operation control procedure in the image forming apparatus 1 is described. Furthermore, a storage area for storing data relating to the image projected on the projection surface 21 is also set.

  The video data calculation unit 82 extracts video data to be output from the video data stored in the video data storage unit 81. The video data calculation unit 82 has a function of outputting video data in accordance with the angles of the light reflection unit 511e and the mirror 121. The drawing timing generation unit 83 has a function of generating a synchronization signal from information on the angles of the light reflection unit 511e and the mirror 121. The light source modulation unit 84 has a function of separating video data into luminances of red, blue, and green colors and outputting video signals of the respective colors to the light source unit 4. The drive signal instruction unit 85 has a function of generating a signal for rotating the actuator 51. The angle instruction unit 86 has a function of generating a signal indicating the angle of the mirror 121.

  In the light source unit 4, the red laser light source 41r is connected to the red driving circuit 410r. The green laser light source 41g is connected to the green driving circuit 410g, and the blue laser light source 41b is connected to the blue driving circuit 410b. The red drive circuit 410r drives the red laser light source 41r in response to the red video signal output from the light source modulator 84. Similarly, the green driving circuit 410g drives the green laser light source 41g corresponding to the green video signal output from the light source modulation unit 84. Further, the blue drive circuit 410b drives the blue laser light source 41b in response to the blue video signal output from the light source modulator 84. The light source modulator 84 separates the video data into red, green, and blue signals. Then, the light source unit 4 irradiates the projection surface 21 with red, green, and blue laser light 44. The projection surface 21 can irradiate a color image by mixing the laser beams 44 of the respective colors.

  Next, the operation of the image forming apparatus 1 when drawing an image on the projection surface 21 will be described. First, video data is input to the image forming apparatus 1. The input video data is temporarily stored in the video data storage unit 81. The video data calculation unit 82 reads the video data from the video data storage unit 81 and draws an image using the video data. In this case, the video data calculation unit 82 may start drawing an image after storing all the video data in the video data storage unit 81.

  Further, when a part of the video data is stored in the video data storage unit 81, the video data calculation unit 82 may start drawing an image. In this method, the operation control device 8 stores the video data in the video data storage unit 81 in parallel with the drawing of the image. First, at least one frame of video data is stored in the video data storage unit 81, and then image drawing is started.

  The light source modulator 84 receives the luminance data of each color from the video data calculator 82. Then, the luminance data is separated into luminance data for each color and output to the light source unit 4. The red drive circuit 410r, the green drive circuit 410g, and the blue drive circuit 410b of the light source unit 4 modulate the red laser light source 41r, the green laser light source 41g, and the blue laser light source 41b according to the luminance data of each color. In other words, the red laser light source 41r, the green laser light source 41g, and the blue laser light source 41b are turned on / off, the output is adjusted, and the like.

  The drawing timing generation unit 83 generates drawing timing information and drawing line information. The drawing timing information is output to the video data calculation unit 82, and the drawing line information is output to the drive signal instruction unit 85. The drawing timing information includes drawing timing information and the like. The drawing line information includes information on the position in the vertical direction 21b of the drawing lines constituting the image. The position information of the drawing line may be set as the position in the vertical direction 21b of the drawing line. For example, the position information of the drawing line may be set as position information such as both ends and the center of the drawing line.

  The angle detector 52 of the actuator 51 detects the angle and deflection angle of the movable plate 511a. Then, the angle detection unit 52 outputs information on the angle and the deflection angle to the drawing timing generation unit 83 of the operation control device 8. In addition, the angle detector 13 of the galvanometer mirror 12 detects the angle of the mirror 121. Then, the angle information of the mirror 121 at that angle is output to the angle instruction unit 86 of the operation control device 8.

  When drawing of one drawing line ends, the drawing timing generation unit 83 outputs target angle information of the drawing line to be drawn next to the angle instruction unit 86. Specifically, the drawing timing generation unit 83 outputs target angle information of the mirror 121 when the laser beam 44 is irradiated with the drawing start point of the drawing line to be drawn next. The target angle of the mirror 121 is set so that the vertical interval between adjacent drawing start points is constant. The angle instruction unit 86 compares the angle of the mirror 121 detected by the angle detection unit 13 with the target angle of the mirror 121. Then, correction is performed so that the angle difference becomes 0, and drive data is output to the drive unit 124 of the galvanometer mirror 12.

  The drive unit 124 drives the motor 122 based on the drive data. Thereby, when the laser beam 44 is irradiated to the drawing start point, the angle of the mirror 121 becomes the target angle.

  The scanning speed of the laser beam 44 in the vertical direction 21b may be constant so that the angular velocity of the mirror 121 is constant from the drawing start point to the drawing end point in each drawing line. Alternatively, the angular speed of the mirror 121 may be gradually changed, and the scanning speed of the laser light 44 in the vertical direction 21b may be gradually changed.

  The drawing timing generation unit 83 outputs drawing line information to the drive signal instruction unit 85. The drawing line information is information indicating whether or not to apply a drive signal. Then, the drive signal instruction unit 85 outputs drive data such as data indicating the magnitude and frequency of the drive signal to the drive unit 517 of the actuator 51.

  The drive unit 517 supplies a drive signal corresponding to the drive data to the coil 515. The coil 515 passes a current having a predetermined magnitude and a predetermined frequency, generates a predetermined magnetic field, and resonates the movable plate 511a. In this way, the image forming apparatus 1 draws an image by sequentially scanning the laser beam 44 on the drawing line of the drawing area 142 while adjusting the deflection angle of the movable plate 511a.

  FIG. 7 is a schematic diagram for explaining the operation of the image forming apparatus. The diagram on the left side of FIG. 7 shows a state in which the image forming apparatus 1 irradiates the laser beam 44 as seen from a direction parallel to the projection surface 21. The figure on the right side of FIG. 7 shows a picture projected by the image forming apparatus 1. As shown in FIG. 7, the image forming apparatus 1 performs scanning in the vertical direction 21b (hereinafter referred to as vertical scanning), and in the forward and backward paths of the vertical scanning, scanning in the horizontal direction 21a (hereinafter referred to as horizontal scanning). I do. Note that the image forming apparatus 1 performs video drawing in either the forward or backward pass of vertical scanning. The horizontal scanning process is referred to as a first driving process, and the vertical scanning process is referred to as a second driving process. When drawing, vertical scanning and horizontal scanning are performed in parallel.

  The direction parallel to the projection surface 21 and the direction in which the image forming apparatus 1 irradiates the laser beam 44 are arranged so as to cross obliquely. Accordingly, when the image forming apparatus 1 performs horizontal scanning while changing the depression angle without changing the deflection angle of the light reflecting portion 511e, the length scanned by the laser light 44 becomes shorter as it is closer to the image forming apparatus 1. The left end of the place where the laser beam 44 can irradiate the projection surface 21 is a left end line 44a, and the right end of the place where the laser light 44 can be irradiated is a right end line 44c. An interval in the horizontal direction 21 a between the left end line 44 a and the right end line 44 c is defined as a deflection width 44 d of the laser light 44. The swing width 44d indicates the interval in the horizontal direction 21a irradiated with the laser light 44 when the movable plate 511a rotates in the light emitting state. The vibration width 44 d of the laser beam 44 is narrower as it is closer to the image forming apparatus 1 and longer as it is farther from the image forming apparatus 1.

  When a linear portion of the locus of the laser beam 44 irradiating the projection surface 21 is a drawing line 141, a plurality of drawing lines 141 are formed and arranged in a zigzag manner. Of the drawing lines 141, the left end in the drawing and the right end in the drawing are not suitable for drawing because the angular velocity (speed) of the mirror 121 is small. For this reason, a drawing area 142, which is an area for drawing an image, except for the ends on both sides is set. The shape of the drawing area 142 is not particularly limited, but is set to be rectangular or square, for example.

  When the deflection angle of the movable plate 511 a is constant, the deflection width of the laser light 44 in the light emission state changes according to the angle of the mirror 121. The position in the vertical direction 21 b on the projection surface 21 scanned with the laser light 44 becomes longer as the position is farther from the image forming apparatus 1. Therefore, in this image forming apparatus 1, adjustment is made so that the deflection angle of the movable plate 511 a becomes smaller as the position in the vertical direction 21 b on the projection surface 21 scanned with the laser beam 44 is farther from the image forming apparatus 1. Then, adjustment is made so that the fluctuation width of the laser light 44 in the light emission state is always larger than the width of the drawing region 142.

  Specifically, as the position of the vertical direction 21b on the projection surface 21 on which the laser beam 44 is scanned moves away from the image forming apparatus 1, the deflection angle of the movable plate 511a is gradually decreased, and the laser in the light emitting state is obtained. The fluctuation width of the light 44 is always larger than the width of the drawing area 142.

  That is, the image forming apparatus 1 controls the deflection angle of the laser beam 44 so that the left end line 44a and the right end line 44c are parallel by controlling the deflection angle of the movable plate 511a. Thereby, the time opening efficiency which is the ratio of the time which drawing occupies in the time which scans 1 screen can be made high.

  For each odd-numbered drawing line 141 from the upper side of the drawing area 142 in the drawing, it is preferable to adjust the angle and angular velocity of the mirror 121 so that the vertical interval between adjacent drawing lines 141 is constant. Further, it is preferable to adjust the angle and angular velocity of the mirror 121 so that the vertical spacing between adjacent drawing lines 141 is constant for each even-numbered drawing line 141 from the upper side in the drawing. Thereby, the distortion of the image in the vertical direction can be prevented.

  The angles and angular velocities of the mirrors 121 are set to predetermined values so that the vertical intervals between adjacent drawing lines 141 are constant at both ends of the drawing region 142 in the horizontal direction 21a. That is, the angle and angular velocity of the mirror 121 are set so that the interval between the adjacent drawing start points in the vertical direction 21b is constant. The both end portions of each drawing line 141 are drawing start points, and the image can be projected without being distorted by making the interval between the both end portions constant. The angular velocity of the mirror 121 is set to be smaller as the position of the drawing line 141 in the vertical direction 21b is farther from the image forming apparatus 1. Thereby, distortion of the image in the vertical direction 21b can be prevented with relatively simple control.

  FIG. 8 is a graph showing the transition of the deflection angle of the actuator. In FIG. 8, the vertical axis indicates the deflection angle θ of the movable plate, and the upper side in the figure is larger than the lower side. The horizontal axis shows the passage of time and changes from the left side to the right side in the figure. The time axis shifts in the order of the drive signal application period, the drawing period, and the return period, and then shifts to the drawing period after the return period. And it changes so that a blanking period and a drawing period may be repeated. The deflection angle transition line 30 is a line indicating the transition of the deflection angle of the actuator 51. The drawing angle transition line 31 is a line indicating a transition of the drawing angle. The drawing angle indicates the deflection angle of the movable plate 511a necessary for drawing an image.

  In the drive signal applying section, the operation control device 8 applies a drive signal to the energizing means 516. Then, the energizing means 516 causes the movable plate 511a to be inclined by passing a current through the coil 515. Therefore, the deflection angle transition line 30 becomes a large angle, and the connecting portion 511c and the connecting portion 511d are twisted. Next, in the drawing section, the operation control device 8 does not give a drive signal to the energization means 516. The energization means 516 stops energization of the coil 515. At this time, the movable plate 511a releases the energy stored in the connecting portion 511c and the connecting portion 511d while rotating. In other words, the movable plate 511a vibrates freely. Therefore, the deflection angle transition line 30 gradually decreases to a smaller angle.

  In the blanking period as the vertical blanking period, the operation control device 8 gives a drive signal to the energizing means 516. Then, the energizing means 516 causes the movable plate 511a to be inclined by passing a current through the coil 515. Therefore, the deflection angle transition line 30 becomes a large angle, and the connecting portion 511c and the connecting portion 511d are twisted. Then, the blanking interval and the drawing interval are repeated. In each section, the deflection angle transition line 30 is set to be larger than the drawing angle transition line 31. That is, the maximum deflection angle of the actuator 51 is set so that the deflection angle of the movable plate 511a is always greater than the drawing angle during the drawing period.

  The swing angle of the movable plate 511a is controlled by whether or not the energizing means 516 gives a drive signal to the coil 515. The energizing means 516 applies a drive signal having a magnitude and frequency that provides a desired maximum deflection angle θ in a resonance state to the coil 515. Thereby, the movable plate 511a can be reliably resonated and driven efficiently. The blanking period corresponds to a driving period 38 in which a driving signal is applied, and the drawing period corresponds to an inertia driving period 37 in which a driving signal is not applied.

  FIG. 9 is a graph showing the transition of the drive signal for driving the movable plate. In FIG. 9, the vertical axis indicates the magnitude of the drive signal, and the drive signal indicates a signal for the operation control device 8 to drive the coil 515. The horizontal axis shows the passage of time, and the time changes from the left side to the right side. Then, on the time axis, the drive period 38 and the inertial drive period 37 are alternately switched.

  The drive signal transition line 32 is a line indicating a transition of a signal for driving the coil 515 by the operation control device 8. As indicated by the drive signal transition line 32, the drive signal is a sine wave during the drive period 38. The drive signal instruction unit 85 gives a drive signal having a magnitude and a frequency that are the maximum deflection angle of the actuator 51. As a result, the actuator 51 is driven to resonate in a one-degree-of-freedom vibration system. Then, no drive signal is given within the inertial drive period 37. Further, the wave number of the sine wave applied during the driving period 38 is not particularly limited. It is only necessary to set an appropriate deflection angle for the movable plate 511a, and the number of sine waves applied during the driving period 38 may be plural or only once. Since the control is easier than when the number of sine waves is small, the electric circuit to be controlled can be a simple circuit.

  FIG. 10 is a graph showing the transition of the rotation of the movable plate and the drive signal. In FIG. 10, the vertical axis indicates the magnitude of the drive signal for driving the coil 515 and the angle at which the movable plate 511a rotates. The horizontal axis indicates the passage of time in the driving period 38, and the time changes from the left side to the right side. The movable plate angle transition line 33 indicates the transition of the angle at which the movable plate 511a rotates. A drive signal transition line 34 indicates a transition of a drive signal for the operation control device 8 to drive the coil 515. The phase of the movable plate angle transition line 33 and the phase of the drive signal transition line 34 are the same phase. A driving force by the permanent magnet 514 and the coil 515 is applied in the same direction as the direction in which the movable plate 511a rotates. Thereby, the drive unit 517 can drive the actuator 51 efficiently.

  FIG. 11 is a graph showing the change with time of the deflection angle of the movable plate. In FIG. 11, the vertical axis represents the deflection angle of the movable plate, and the upper side in the figure is larger than the lower side. The horizontal axis shows the passage of time, and the time changes from the left side to the right side in the figure. The time axis repeats the inertial drive period 37 and the drive period 38 alternately. The deflection angle transition line 35 indicates the transition of the deflection angle of the movable plate 511a at the time of drawing. Therefore, the deflection angle transition line 35 corresponds to the horizontal scanning operation. The inertial driving period 37 and the driving period 38 are included in the time for drawing one frame. In the inertial drive section, the swing angle of the movable plate 511a gradually decreases from the maximum swing angle. Next, after the deflection angle reaches the minimum deflection angle, the deflection angle increases to the maximum deflection angle in the drive section. Again, the swing angle gradually decreases in the inertial drive section. Thereafter, the swing angle repeats the same operation.

  FIG. 12 is a graph showing the change over time of the mirror angle of the galvanometer mirror. In FIG. 12, the vertical axis indicates the angle of the mirror, and the upper side in the figure is larger than the lower side. The horizontal axis shows the passage of time, and the time changes from the left side to the right side in the figure. And the time axis repeats the inertial drive section and the drive section alternately. The mirror angle transition line 36 indicates the transition of the mirror angle of the galvanometer mirror. Therefore, the mirror angle transition line 36 corresponds to the vertical scanning operation. A display period during which an image is drawn is performed during the inertial drive period 37, and a non-display period during which no image is drawn is performed during the drive period 38.

  The mirror angle transition line 36 increases the mirror angle linearly in the inertial drive section. During this time, a predetermined number of horizontal scans are performed. The mirror angle transition line 36 decreases the mirror angle during the driving period 38. Each timing such as a timing for starting drawing of the next frame in the driving period 38 can be adjusted.

As described above, this embodiment has the following effects.
(1) According to the present embodiment, the first driving process has the driving period 38 and the inertial driving period 37. In the driving period 38, a driving force is applied to rotate the movable plate 511a, and energy is accumulated in the connecting portion 511c and the connecting portion 511d having a spring property. In the inertia driving period 37, the movable plate 511a is rotated using the restoring force of the connecting portion 511c and the connecting portion 511d. Accordingly, by applying a driving force to the movable plate 511a with a predetermined interval and rotating the movable plate 511a, the laser beam 44 can be scanned using the restoring force of the connecting portion 511c and the connecting portion 511d. As a result, the control for scanning the laser beam 44 can be easily performed.

  (2) According to this embodiment, the driving force by the permanent magnet 514 and the coil 515 is applied in the same direction as the direction in which the movable plate 511a rotates. Thereby, the drive unit 517 can drive the actuator 51 efficiently.

  (3) According to the present embodiment, the energization means 516 gives a drive signal to the coil 515 when drawing is not performed within the vertical blanking period. When a driving force is applied to the movable plate 511a, the rotational speed of the movable plate 511a changes abruptly, so the speed at which the laser beam 44 is scanned changes abruptly. If the drawing is performed when the scanning speed of the laser beam 44 is rapidly changed, the image is disturbed. In the present embodiment, since a driving force is applied to the movable plate 511a without affecting drawing, a high-quality image can be drawn.

  (4) According to the present embodiment, the driving force may be applied only once in one driving period 38. At this time, it is possible to easily apply the driving force as compared with the method in which the driving force is applied a plurality of times in one driving period 38. As a result, the circuit for controlling the application of the driving force can be simplified.

  (5) According to the present embodiment, the operation control device 8 operates the movable plate 511 a so that the deflection angle transition line 30 in FIG. 8 changes at a larger angle than the drawing angle transition line 31. That is, the driving force is applied so that the range of the laser beam 44 that scans in the horizontal direction 21 a is larger than the range of the drawing region 142. Therefore, drawing can be reliably performed in the horizontal direction 21a.

In addition, this embodiment is not limited to embodiment mentioned above, A various change and improvement can also be added. A modification will be described below.
(Modification 1)
In the first embodiment, the collimator lenses 42r, 42g, and 42b are used to make the laser beam 44 a parallel beam. However, the present invention is not limited to this. An optical element such as a collimator mirror may be used. Also in this case, a thin beam of parallel light beams can be formed. Further, when parallel light beams are emitted from the red laser light source 41r, the green laser light source 41g, and the blue laser light source 41b, the collimator lenses 42r, 42g, and 42b are not necessarily required and can be omitted. Since the number of optical elements can be reduced, a simple device can be obtained.

(Modification 2)
In the first embodiment, the red laser light source 41r, the green laser light source 41g, and the blue laser light source 41b are used. However, the present invention is not limited to this. A light source such as a light emitting diode may be used. An image similar to a laser light source can be formed. Furthermore, a simple and lightweight device can be obtained.

(Modification 3)
In the first embodiment, the dichroic mirrors 43r, 43g, and 43b are arranged in this order, and the laser beam 44 is coupled. The order in which the dichroic mirrors 43r, 43g, and 43b are combined is not particularly limited. For example, the dichroic mirrors 43g, 43b, and 43r may be arranged in this order, and the dichroic mirrors 43b, 43r, and 43g may be arranged in this order. The order of the colors of the laser beams 44 to be combined may be set freely.

(Modification 4)
In the first embodiment, the electromagnetic drive using the coil 515 and the permanent magnet 514 is used to drive the actuator 51. The method for driving the actuator 51 is not limited to this method. For example, the driving method may be piezoelectric driving using a piezoelectric element or electrostatic driving using electrostatic attraction. In the case of piezoelectric drive or electrostatic drive, a voltage signal is used as a drive signal. You may set according to the magnitude | size and weight of the light reflection part 511e.

(Modification 5)
In the first embodiment, the laser light 44 emitted from the light source unit 4 is reflected on the light reflecting portion 511 e of the actuator 51, and then reflected on the reflecting surface of the mirror 121 of the galvanometer mirror 12. The order of reflection is not limited to this. The laser beam 44 emitted from the light source unit 4 may be first reflected on the reflecting surface of the mirror 121 of the galvanometer mirror 12 and then reflected on the reflecting surface of the light reflecting portion 511 e of the actuator 51. That is, it may be configured such that the vertical scanning is performed first and then the horizontal scanning is performed.

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 4 ... Light source unit as an emission part, 5 ... Optical scanning part, 8 ... Operation control apparatus as a drive control part, 21 ... Projection surface, 37 ... Inertial drive period, 38 ... Drive period, 44 ... Laser light as light 52. Angle detector 121 Mirror as reflection surface 511 c 511 d Connection portion as spring 511 e Light reflection portion as reflection surface 517 Drive unit

Claims (6)

A method of driving an image forming apparatus that reflects light on a reflecting surface to form an image on a projection surface,
A first driving step of rotating the reflecting surface to scan light in a first direction; and a second driving step of rotating the reflecting surface to scan light in a second direction intersecting the first direction; Have
The reflecting surface is connected to a spring, and the first driving step applies a driving force to rotate the reflecting surface and accumulate energy in the spring, and the reflecting surface is used to restore the reflecting surface using the restoring force of the spring. And an inertial driving period for rotating the image forming apparatus. A driving method of an image forming apparatus according to claim 1,
The driving method of an image forming apparatus, wherein the driving force is applied in the same direction as the direction in which the reflecting surface rotates during the driving period. A driving method of an image forming apparatus according to claim 2,
The driving method of an image forming apparatus, wherein the driving period is performed within a vertical blanking period in which drawing is not performed. A driving method of an image forming apparatus according to claim 3,
A driving method of an image forming apparatus, wherein the driving force is applied once in one driving period. A method for driving an image forming apparatus according to claim 4,
A driving method of an image forming apparatus, wherein the driving force is applied so that a range of light scanning in the first direction is larger than a range of the image. An image forming apparatus that scans light onto a projection surface to form an image,
An emission part for emitting light;
It has a reflecting surface that reflects and rotates light emitted from the emitting unit, and scans in the first direction with respect to the projection surface and is slower than the scanning speed for scanning in the first direction. An optical scanning unit that scans in a second direction intersecting the first direction at a scanning speed;
A drive control unit for controlling the optical scanning unit,
The drive control unit includes a drive unit that scans the reflection surface in the first direction, and an angle detection unit that detects an angle of the reflection surface in the second direction,
The driving unit applies a driving force to the reflecting surface according to the angle detected by the angle detecting unit to rotate the reflecting surface and store energy in a spring, and uses the restoring force of the spring to perform the reflection. An image forming apparatus characterized by rotating a surface.

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