JP2011100074A - Optical device, optical scanner and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical device in which the difference in luminance of reflected light depending on the scanning position on a face to be scanned is reduced, and to provide an optical scanner and an image forming apparatus. <P>SOLUTION: The optical device includes: a scanning part 2 which has a light reflection member 21 which reflects light and a supporting member 26 which supports the light reflection member 21 rockably around an axis A, and scans the reflected light reflected on the light reflection member 21 by the rocking of the light reflection member 21 on a face to be scanned; and an actuator 3 which varies the spacial position of the scanning part 2 with respect to the face to be scanned for varying the scanning speed of the reflected light in a predetermined direction on the face to be scanned. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  Some embodiments according to the present invention relate to an optical device, an optical scanning device, and an image forming apparatus that are manufactured by, for example, a MEMS (Micro Electro Mechanical System) technique and in which a light reflecting member swings around a predetermined axis.

  In general, in an optical scanning apparatus including this type of optical device, for example, a light reflecting member is resonantly oscillated, and the angle of the light reflecting member is changed sinusoidally. For this reason, for example, when the light reflecting member is swung and the reflected light is scanned in the horizontal direction (lateral direction) of the scanned surface, the scanning speed of the reflected light at the center of the scanned surface is the fastest. The scanning speed decreased toward the both ends of the. Therefore, when light is incident from a light source having a constant light amount, there is a problem that brightness (luminance) varies depending on the scanning position of the surface to be scanned.

  Conventionally, in order to solve this problem, a laser projection apparatus having a projection optical system for projecting light (laser) from an optical device (scanning apparatus) onto a scanned surface (screen), An apparatus having constant velocity (see, for example, Patent Document 1) is known.

JP 2008-164957 A

  However, since the thing of patent document 1 is provided with an expensive projection optical system, the manufacturing cost was high. In addition, since the reflected light reflected by the optical device passes through the projection optical system and is projected onto the surface to be scanned, due to the influence of the transmittance or reflectance of the optical elements (such as lenses) constituting the projection optical system, There is a problem that reflected light to be scanned on the surface to be scanned is reduced.

  Some aspects of the present invention have been made in view of the above-described problems, and an optical device, an optical scanning apparatus, and an image forming device capable of reducing a difference in brightness of reflected light depending on a scanning position on a surface to be scanned. One object is to provide a device.

  An optical device according to the present invention includes a light reflecting member that reflects light and a support member that supports the light reflecting member so as to be swingable around a predetermined axis. A scanning unit capable of scanning the surface to be scanned with the reflected light reflected by the reflecting member, and a spatial position of the scanning unit with respect to the surface to be scanned in order to change the scanning speed of the reflected light on the surface to be scanned in a predetermined direction. And changing means for changing.

  According to this configuration, the spatial position of the scanning unit with respect to the scanned surface is changed in order to change the scanning speed of the reflected light in the predetermined direction on the scanned surface. Here, the reflected light on the surface to be scanned is changed by changing the spatial position of the scanning unit with respect to the surface to be scanned, for example, by rotating the scanning unit around the predetermined axis or moving the scanning unit. The scanning speed can be changed. Therefore, for example, the scanning speed of the reflected light on the scanned surface can be set to a predetermined speed by changing the spatial position of the scanning unit with respect to the scanned surface in accordance with the swinging motion of the light reflecting member. . As a result, when a certain amount of light is incident on the light reflecting member, the difference in the brightness of the reflected light depending on the scanning position on the surface to be scanned can be reduced.

  Preferably, control means for controlling the changing means is further provided so that the scanning speed changed by the changing means becomes a predetermined speed.

  According to this configuration, the changing unit is controlled so that the scanning speed changed by the changing unit becomes a predetermined speed. Thereby, for example, the changing means is controlled so as to cancel the change in the scanning speed on the surface to be scanned due to the swinging motion of the light reflecting member, so that the scanning speed on the surface to be scanned after the change is set to a predetermined speed. can do. As a result, when a certain amount of light is incident on the light reflecting member, the brightness of the reflected light on the surface to be scanned can be made constant or substantially constant.

  Preferably, a scanning unit support member that supports the scanning unit and a light source unit that causes light to enter the light reflecting member are further provided.

  According to this configuration, the scanning unit is supported by the scanning unit support member. Thereby, for example, the scanning unit support member moves (moves), whereby the spatial position of the scanning unit with respect to the surface to be scanned can be easily changed.

  Preferably, the changing unit rotates the scanning unit around the predetermined axis.

  According to such a configuration, the scanning unit is rotated around the predetermined axis by the changing unit. Thereby, for example, the scanning unit rotates around the predetermined axis in accordance with the swinging motion of the light reflecting member around the predetermined axis, so that the changed scanning speed on the scanned surface can be easily set to the predetermined speed. Can do. As a result, when a constant amount of light is incident on the light reflecting member, the brightness of the reflected light on the surface to be scanned can be easily made constant or substantially constant.

  Preferably, the changing means is a piezoelectric actuator.

  According to such a configuration, the changing means for rotating the scanning unit around the predetermined axis is the piezoelectric actuator. Thereby, for example, the scanning unit can be easily rotated around the predetermined axis by arranging the piezoelectric actuators on both sides of the predetermined axis and extending and contracting.

  Preferably, the changing means is a linear actuator.

  According to this configuration, the changing unit that rotates the scanning unit around the predetermined axis is the linear actuator. Thereby, for example, the scanning unit can be easily rotated around the predetermined axis by arranging the linear actuators on both sides of the predetermined axis and expanding and contracting. Further, the linear actuator can linearly rotate (displace) the scanning unit with respect to the input control signal.

  Preferably, the changing means is a motor.

  According to this configuration, the changing unit that rotates the scanning unit around the predetermined axis is the motor. Thereby, for example, by arranging the scanning unit so that the rotation axis (rotating axis) of the rotor (rotor) and the predetermined axis of the scanning unit coincide (coaxial), the scanning unit can be easily set to the predetermined unit. It can be rotated around an axis.

  Preferably, the changing unit moves the scanning unit so as to change the distance between the scanning unit and the surface to be scanned.

  According to this configuration, the scanning unit is moved by the changing unit so as to change the distance between the scanning unit and the surface to be scanned. Accordingly, for example, the scanning unit moves so as to change the distance between the scanning unit and the surface to be scanned in accordance with the swinging motion of the light reflecting member, so that the scanning speed on the surface to be scanned after the change can be easily achieved. A predetermined speed can be obtained. As a result, the brightness of the reflected light on the surface to be scanned can be easily made constant or substantially constant when a certain amount of incident light is incident on the light reflecting member.

  Preferably, the changing unit is a moving body in which a scanning unit and a light source unit are installed, and approaches or moves away from the scanned surface.

  According to such a configuration, the changing unit is a moving body in which the scanning unit and the light source unit are installed, and approaches the scanned surface or moves away from the scanned surface. Accordingly, for example, the moving unit moves in the direction perpendicular to the surface to be scanned, so that the scanning unit can be easily moved so as to change the distance between the scanning unit and the surface to be scanned. The moving body is provided with a light source unit that causes light to enter the light reflecting member of the scanning unit. Thereby, when the moving body moves, the scanning unit (light reflecting member) and the light source unit move together, so that light from the light source can be easily incident on the light reflecting member.

  An optical scanning device according to the present invention includes a first scanning unit that scans reflected light in a first direction, and the first scanning unit is the above-described optical device according to the present invention.

  According to this configuration, the first scanning unit that scans the reflected light in the first direction is the optical device according to the present invention described above. Thereby, for example, the scanning speed of the reflected light in the longitudinal direction (main scanning direction) of the surface to be scanned can be set to a predetermined speed. Here, when the reflected light is scanned in the longitudinal direction of the surface to be scanned, it is necessary to shake more greatly during the same predetermined time (1 / frequency (frequency)) than in the case of scanning in the short direction. Therefore, it was necessary to increase the scanning speed. As a result, the change in the scanning speed of the reflected light in the longitudinal direction of the surface to be scanned becomes larger, and the difference in brightness depending on the scanning position tends to increase. Therefore, by setting the scanning speed of the reflected light in the longitudinal direction (main scanning direction) of the scanned surface to a predetermined speed, it is possible to reduce the difference in brightness depending on the scanning position in the longitudinal direction of the scanned surface. An optical scanning device having scanning characteristics can be realized.

  Preferably, a second scanning unit that scans the reflected light in the second direction is further provided, and the second scanning unit is the above-described optical device according to the present invention.

  According to such a configuration, since the second scanning unit that scans the reflected light in the second direction is the optical device according to the present invention described above, for example, in the lateral direction (sub-scanning direction) of the surface to be scanned. The scanning speed of the reflected light can be set to a predetermined speed. Thereby, even in the short direction of the surface to be scanned, the difference in brightness depending on the scanning position can be reduced, and an optical scanning device having further excellent scanning characteristics can be realized.

  An image forming apparatus according to the present invention includes the above-described optical scanning device according to the present invention.

  According to such a configuration, since the above-described optical scanning device according to the present invention is provided, for example, in the longitudinal direction of the surface to be scanned, the difference in brightness depending on the scanning position can be reduced, and light having excellent scanning characteristics. A scanning device can be realized. Thereby, a high-resolution image can be formed, and an image forming apparatus having excellent drawing characteristics can be realized.

FIG. 1 is a plan view for explaining the configuration of the optical device according to the first embodiment of the present invention. It is the II sectional view taken on the line in FIG. It is the II-II arrow directional cross-sectional view shown in FIG. It is a perspective view explaining operation | movement of the actuator shown in FIG.2 and FIG.3. It is a perspective view explaining operation | movement of the actuator shown in FIG.2 and FIG.3. It is a top view explaining the relationship between the optical device shown in FIG. 1, and a to-be-scanned surface. It is a front view explaining the to-be-scanned surface which scans the reflected light of the optical device shown in FIG. It is a graph which shows an example of the rocking | fluctuation angle of a light reflection member. It is a graph which shows an example of the speed of the rocking | fluctuation angle of a light reflection member. It is a graph which shows an example of the scanning speed changed by the actuator. It is a top view explaining the other example of the to-be-scanned surface shown in FIG. FIG. 7 is a plan view for explaining another example of the scanned surface shown in FIG. 6. It is a perspective view explaining the structure in 2nd Embodiment of the optical device which concerns on this invention. It is a top view explaining the structure in 3rd Embodiment of the optical device which concerns on this invention. It is a graph which shows an example of the rocking | fluctuation angle of a light reflection member. It is a graph which shows an example of the position of a trolley. It is a graph which shows an example of the scanning speed changed with the trolley | bogie. It is the schematic explaining the structure in 1st Embodiment of the optical scanning device concerning this invention. It is the schematic explaining the structure in 2nd Embodiment of the optical scanning device concerning this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic. Therefore, specific dimensions and the like should be determined in light of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings. Note that the X axis, Y axis, and Z axis shown in the drawings are coordinate axes orthogonal to each other, the Y axis is orthogonal to the X axis in the horizontal direction, and the Z axis is orthogonal to the X axis in the vertical direction. Shall. In the following description, the upper side of the drawing is referred to as “upper”, the lower side as “lower”, the left side as “left”, and the right side as “right”.

<Optical device>
(First embodiment)
1 to 12 show a first embodiment of an optical device according to the present invention. FIG. 1 is a plan view for explaining the configuration of the optical device according to the first embodiment of the present invention. The optical device 1 is for changing the direction of light by reflecting incident light, for example, an optical scanning device (optical scanner) that scans (irradiates) an object with light incident from a light source. Used for. As shown in FIG. 1, the optical device 1 includes a scanning unit 2 that scans reflected light (hereinafter referred to as reflected light) onto an object, for example, a screen (scanned surface). The scanning unit 2 includes a light reflecting member 21 that reflects light, and a support member 26 that supports the light reflecting member 21 so as to be swingable about an axis A.

  The support member 26 is a frame-shaped frame portion (frame) 27 that surrounds the light reflecting member 21 provided inside, and a pair of shaft members 28 that are supported by the frame portion 27 and support the light reflecting member 21 on the axis A. And comprising. The light reflecting member 21 and the pair of shaft members 28 constitute a vibration system SI in which the pair of shaft members 28 are twisted and deformed by the swinging means 6 described later, and the light reflecting member 21 swings around the axis A. .

  The support member 26, that is, the frame portion 27 and the pair of shaft members 28 are integrally formed, for example, by etching a silicon substrate. Similarly, the light reflecting member 21 and the pair of shaft members 28 can be integrally formed by etching the silicon substrate. The light reflecting member 21 and the support member 26 are preferably integrally formed so as to be on the same plane or substantially the same plane.

  In the present embodiment, a circular shape is shown as the planar shape of the light reflecting member 21. However, the planar shape is not limited to this, and as long as it plays a role required as the light reflecting member 21 of the optical device 1, an elliptical shape, a rectangular shape, a polygonal shape. Other shapes may be used.

  2 is a cross-sectional view taken along the line I-I shown in FIG. The I-I line shown in FIG. 1 is arranged at a predetermined distance from the axis A. As shown in FIG. 2, a metal film 22 that reflects incident light is formed on one surface (upper surface in FIG. 2) of the light reflecting member 21. The metal film 22 can be formed, for example, by applying a film forming method such as vacuum deposition, sputtering, or metal foil bonding to a silicon substrate that has been formed into a predetermined shape by etching.

  A magnetic body 61 (to be described later) is joined to the other surface (the lower surface in FIG. 2) of the light reflecting member 21 via an adhesive (not shown). The magnetic body 61 is magnetized in a direction orthogonal to the axis A (Y-axis direction in FIG. 1) when the optical device 1 is viewed in plan. That is, the magnetic body 61 has a pair of magnetic poles that are opposed to each other with the axis A and have different polarities.

  As shown in FIG. 2, the optical device 1 includes an actuator 3 to be described later and a counter substrate 5 that faces the scanning unit 2 via the actuator 3. The counter substrate 5 is composed mainly of glass or silicon, for example. A coil 62 is provided on the upper surface of the counter substrate 5.

  3 is a cross-sectional view taken along the line II-II shown in FIG. In FIG. 3, for convenience of explanation, the left side of the magnetic body 61 is an N pole and the right side is an S pole. As shown in FIG. 3, the swinging means 6 includes a magnetic body 61, a coil 62, and a power source 63.

  The magnetic body 61 is, for example, a permanent magnet, and a material obtained by magnetizing a hard magnetic body such as a neodymium magnet, a ferrite magnet, a samarium cobalt magnet, an alnico magnet, or a bonded magnet can be suitably used. In addition, a hard magnetic body (that is, a permanent magnet) already magnetized may be used, or a permanent magnet may be formed by magnetizing the hard magnetic body after the hard magnetic body is provided on the light reflecting member 21.

  The coil 62 is for causing a magnetic field to act on the magnetic body 61, and is provided immediately below the magnetic body 61. That is, the coil 62 is provided to face the lower surface of the light reflecting member 21. Thereby, the magnetic field generated from the coil 62 can be efficiently applied to the magnetic body 61. The coil 62 may be wound around a magnetic core.

  The coil 62 is electrically connected to the power source 63. When an alternating current having a predetermined frequency is supplied from the power source 63, the coil 62 alternately generates a magnetic field directed upward (on the light reflecting member 21 side) and a magnetic field directed downward. That is, the magnetic body 61 (light reflecting member 21) receives a torque in the clockwise (rightward) direction with respect to the axis A in FIG. 3 (this magnetic field is referred to as “magnetic field A1”) and the counterclockwise (counterclockwise) direction. A magnetic field (this magnetic field is referred to as “magnetic field A2”) that receives a torque of 1 is alternately generated. By alternately switching between the magnetic field A1 and the magnetic field A2, the light reflecting member 21 is swung around the axis A while the pair of shaft members 28 are torsionally deformed. As described above, the light reflecting member 21 swings around the axis A, so that the scanning unit 2 scans the reflected light reflected by the light reflecting member 21 onto an object, for example, a screen (scanned surface). Is possible.

  The predetermined frequency of the alternating current supplied by the power source 63 is preferably set so as to match or substantially match the natural frequency (torsional resonance frequency) of the vibration system SI. Thus, by utilizing resonance, when the light reflecting member 21 is swung around the axis A, the swing angle (swing angle) can be increased with less power consumption.

  In the present embodiment, the swing method using the electromagnetic force between the magnetic body 61 and the coil 62 is shown, but the present invention is not limited to this, and a method using electrostatic attraction or a piezoelectric element as the swing means. The swing method used may be adopted. For example, in the case of a system using electrostatic attraction, the magnetic body 61 is not necessary, and one or more electrodes are provided on the counter substrate 5 at a position facing the light reflecting member 21 instead of the coil 62. Installed. Then, by applying an alternating voltage of a predetermined frequency between the light reflecting member 21 and the electrode, an electrostatic attractive force is generated between the light reflecting member 21 and the electrode, and the pair of shaft members 28 are twisted and deformed. However, the light reflecting member 21 may be swung around the axis A.

  4 and 5 are perspective views for explaining the operation of the actuator shown in FIGS. As shown in FIGS. 4 and 5, the four actuators 3 support the corners of the rectangular frame portion 27, respectively. Each actuator 3 is, for example, a piezoelectric actuator composed of a piezoelectric element (piezo element), a linear actuator, or the like. Each actuator 3 is electrically connected to a control circuit 4 to be described later, and expands and contracts under the control of the control circuit 4.

  Specifically, the actuator 3 rotates the scanning unit 2 around the axis A by expanding and contracting. That is, as shown in FIG. 4, the two actuators 3 that support the right side of the frame portion 27 are contracted downward as indicated by arrows, and the two actuators 3 that support the left side of the frame portion 27 are indicated by arrows, respectively. Thus, the scanning unit 2 rotates (rotates) clockwise (clockwise) with respect to the axis A. Further, as shown in FIG. 5, the two actuators 3 supporting the right side of the frame portion 27 extend upward as indicated by arrows, and the two actuators 3 supporting the left side of the frame portion 27 are indicated by arrows, respectively. By contracting downward in this way, the scanning unit 2 rotates (rotates) counterclockwise (counterclockwise) with respect to the axis A.

Next, the scanning speed of the reflected light on the surface to be scanned will be described with reference to FIGS. 6 is a plan view for explaining the relationship between the optical device shown in FIG. 1 and the surface to be scanned, and FIG. 7 is a front view for explaining the surface to be scanned for scanning the reflected light of the optical device shown in FIG. FIG. As described above, the scanning unit 2 shown in FIG. 1 causes the light reflecting member 21 to swing around the axis A so that the reflected light reflected by the light reflecting member 21 is reflected on the surface to be scanned, for example, the screen. Can be scanned. As shown in FIG. 6, the scanning unit 2, strictly speaking, the light reflecting member 21 (not shown) of the scanning unit 2 is located at a distance L from the flat screen SC1. As shown in FIG. 6 or FIG. 7, for example, the scanning unit 2 reflects the incident light C by the light reflecting member 21 and reflects the reflected light D in a predetermined direction (longitudinal direction (lateral direction in FIG. 7)) of the flat screen SC1. To scan. Here, the scanning position of the reflected light D when the light reflecting member 21 is not swinging is X _0, and the light reflecting member 21 is scanned from the scanning position X ₀ to one side (left side in FIG. 7). Is a plus angle, and the oscillation angle θ of the light reflecting member 21 when scanning from the scanning position X ₀ to the other direction side (the right side in FIG. 7) is a minus angle.

FIG. 8 is a graph showing an example of the swing angle of the light reflecting member, and FIG. 9 is a graph showing an example of the speed of the swing angle of the light reflecting member. In the example shown in FIGS. 6 and 7, the vibration system SI (light reflecting member 21) in the optical device 1 oscillates at a predetermined frequency (frequency), and the reflected light D is scanned at the scanning position X ₁ on the flat screen SC1. And the scanning position X ₂ (X ₁ → X ₀ → X ₂ → X ₀ → X ₁ → X ₀ →...), As shown in FIG. Changes with time (θ = cos (t)). Therefore, the speed ω ₁ of the swing angle θ changes with time as shown in FIG. 9 (ω ₁ = dθ / dt = −sin (t)).

In this way, when the vibration system SI (light reflecting member 21) swings at a predetermined frequency (frequency) to scan the reflected light D, the scanning position x on the flat screen SC1 has a distance L and a swing angle θ. And can be expressed as the following formula (1).
x = L × tan θ (1)

Therefore, the scanning speed before changing the scanning speed by the actuator 3 (hereinafter referred to as the scanning speed before the change) v ₁ can be expressed as the following formula (2).
v ₁ = dx / dt = L × {1 / (cos θ) ² } (2)

Actuator 3 shown in FIGS. 4 and 5, in order to change the scanning speed v ₁ before the change of the reflected light on the flat screen SC1, change the spatial position relative to the plane screen SC1 of the scan section 2. That is, the actuator 3 corresponds to a specific example of changing means in the present invention. The control circuit 4 shown in FIGS. 4 and 5 controls the actuator 3 such that the scanning speed changed by the actuator 3 (hereinafter referred to as the changed scanning speed) v ₂ becomes a predetermined speed. Specifically, the control circuit 4 controls each actuator 3 so that the speed ω _{2 of the} rotation angle that rotates the scanning unit 2 about the axis A cancels the temporal change of the scanning speed v ₁ before the change. Control.

That is, in the expression (2) representing the scanning speed v ₁ before the change, the distance L does not change with the time t, and therefore, the scanning unit 2 is an inverse function of a portion ({1 / (cos θ) ² }) that changes with the time t. by changing the spatial position relative to the plane screen SC1 of, it is possible to the scanning speed v ₂ after the change to a predetermined speed. Therefore, the control circuit 4 controls each actuator 3 so that the rotational angle speed ω ₂ of the scanning unit 2 satisfies the following expression (3).
ω ₂ = (cos θ) ² (3)

FIG. 10 is a graph showing an example of the scanning speed changed by the actuator. As a result of the rotation of the scanning unit 2 about the axis A so as to satisfy the expression (3), as shown in FIG. 10, the changed scanning speed v ₂ is constant or substantially changed while changing its direction (direction) periodically. It becomes constant.

  In the present invention, “changing the spatial position” means changing at least one coordinate (parameter) in a predetermined spatial coordinate system, for example, an orthogonal coordinate system or a polar coordinate system. This includes the case where the section changes the spatial position. For example, when the scanning unit 2 rotates about the axis A, the pair of shaft members 28 in the scanning unit 2 does not change the spatial position with respect to the flat screen SC1, but at least one of the light reflecting member 21 and the frame unit 27. Changes the spatial position with respect to the flat screen SC1, so the scanning unit 2 corresponds to “changing the spatial position” with respect to the flat screen SC1.

  FIG. 11 is a plan view for explaining another example of the scanned surface shown in FIG. 6, and FIG. 12 is a plan view for explaining another example of the scanned surface shown in FIG. In the present embodiment, the case where the optical device 1 is the flat screen SC1 is shown as the scanning surface on which the reflected light is scanned. However, the present invention is not limited to this. For example, it may be a two-sided screen SC2 formed in a concave shape as shown in FIG. 11, or may be a two-sided screen SC3 formed in a concave shape as shown in FIG. Further, it may be a multi-sided screen having three or more sides.

Thus, according to the optical device 1 in the present embodiment, the spatial position of the scanning unit 2 with respect to the flat screen SC1 is changed in order to change the scanning speed of the reflected light on the flat screen SC1 in a predetermined direction. Here, the spatial position of the scanning unit 2 with respect to the flat screen SC1 is changed. For example, the reflection on the flat screen SC1 is performed by rotating the scanning unit 2 around the axis A or moving the scanning unit 2. The light scanning speed v ₁ can be changed. Thus, for example, by changing the spatial position relative to the plane screen SC1 of the scan unit 2 in response to the swinging movement of the light reflecting member 21, to the scanning speed v ₂ of the reflected light on the flat screen SC1 a predetermined speed Is possible. As a result, when a certain amount of light is incident on the light reflecting member 21, it is possible to reduce the difference in brightness depending on the scanning position on the flat screen SC1.

Further, according to the optical device 1 in the present embodiment, the actuator 3 is controlled so that the scanning speed v ₂ changed by the actuator 3 becomes a predetermined speed. Thus, for example, so as to cancel the time variation of the scanning speed v ₁ on the flat screen SC1 by oscillating movement of the light reflecting member 21, since the actuator 3 is controlled, the scanning speed of the changed on the plane screen SC1 v ₂ can be set to a predetermined speed. As a result, when a certain amount of light is incident on the light reflecting member 21, the brightness of the reflected light D on the flat screen SC1 can be made constant or substantially constant.

  Moreover, according to the optical device 1 in the present embodiment, the scanning unit 2 is supported by the scanning unit support member (actuator 3). Thereby, for example, the spatial position of the scanning unit 2 relative to the flat screen SC1 can be easily changed by moving (moving) the scanning unit support member (actuator 3).

Further, according to the optical device 1 in the present embodiment, the scanning unit 2 is rotated around the axis A by the actuator 3. Thereby, for example, the scanning unit 2 rotates about the axis A according to the swinging motion of the light reflecting member 21 about the axis A, so that the changed scanning speed v ₂ on the flat screen SC1 can be easily determined. Can be speed. As a result, when a certain amount of light is incident on the light reflecting member 21, the brightness of the reflected light D on the flat screen SC1 can be easily made constant or substantially constant.

  Further, according to the optical device 1 in the present embodiment, the changing means for rotating the scanning unit 2 around the axis A is a piezoelectric actuator. Accordingly, for example, the scanning unit 2 can be easily rotated around the axis A by arranging the piezoelectric actuators on both sides of the axis A and extending and contracting them.

  Further, according to the optical device 1 in the present embodiment, the changing means for rotating the scanning unit 2 around the axis A is a linear actuator. Accordingly, for example, the scanning unit 2 can be easily rotated around the axis A by arranging and extending the linear actuators on both sides of the axis A. The linear actuator can rotate (displace) the scanning unit 2 linearly with respect to the input control signal.

(Second Embodiment)
FIG. 13 shows a second embodiment of the optical device according to the present invention. Note that the same components as those of the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted.

  The difference between the second embodiment and the first embodiment is that a motor 7 is provided instead of the actuator 3.

  FIG. 13 is a perspective view illustrating the configuration of the optical device according to the second embodiment of the present invention. As shown in FIG. 13, the optical device 1 includes a motor 7. The motor 7 has a rotor (rotor) 7a, and the scanning unit 2 and FIG. 3 are arranged so that the rotation axis (rotary axis) of the rotor 7a and the axis A of the scanning unit 2 coincide (coaxial). The swinging means 6 (not shown) shown in FIG. 6 is installed at the tip of the rotor 7a. Note that the optical device 1 may include a scanning unit support member (not shown) instead of the actuator 3 for supporting the frame unit 27.

  Similarly to the first embodiment, the motor 7 is electrically connected to the control circuit 4 (not shown) shown in FIGS. 4 and 5 and controlled by the control circuit 4 to rotate the rotor 7a ( Rotate. Thus, the scanning unit 2 is rotated about the axis A by the rotation (rotation) of the rotor 7a.

  Thus, according to the optical device 1 in the present embodiment, the changing means for rotating the scanning unit 2 around the axis A is the motor 7. Accordingly, for example, the scanning unit 2 is arranged so that the rotation axis (rotation axis) of the rotor (rotor) 7a and the axis A of the scanning unit 2 are aligned (coaxial), thereby enabling the first embodiment. Similarly, the scanning unit 2 can be easily rotated around the axis A.

(Third embodiment)
14 to 17 show a third embodiment of the optical device according to the present invention. The same components as those in the first embodiment or the second embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  The difference between the third embodiment and the first embodiment is that a carriage 8 is provided instead of the actuator 3.

  FIG. 14 is a plan view for explaining the configuration of the optical device according to the third embodiment of the present invention. As shown in FIG. 14, the optical device 1 emits light to a scanning unit support member (not shown) that supports the scanning unit 2 instead of the actuator 3 and a light reflecting member 21 (not shown) of the scanning unit 2. The light source part 9 to enter and the trolley | bogie 8 are provided. The carriage 8 moves the scanning unit 2 so as to change the distance L between the scanning unit 2 and the flat screen SC1. That is, the carriage 8 corresponds to a specific example of changing means in the present invention.

  Specifically, the carriage 8 is provided with a scanning unit 2, a scanning unit support member (not shown), a swinging means 6 (not shown) shown in FIG. 3, and a light source unit 9. . The carriage 8 moves in the Z-axis direction in FIG. 14 and approaches the flat screen SC1 or moves away from the flat screen SC1. That is, the carriage 8 corresponds to a specific example of the moving body in the present invention.

  The light source unit 9 includes a light source 9 a that emits incident light C, and a mirror 9 b that reflects the incident light C emitted from the light source 9 a and enters the light reflecting member 21 of the scanning unit 2. The carriage 8 is provided with a light source unit 9 that allows incident light C to enter the light reflecting member 21 of the scanning unit 2. Thus, when the carriage 8 moves, the scanning unit 2 (light reflecting member 21) and the light source unit 9 move together, so that the incident light C from the light source 9a can easily enter the light reflecting member 21. Can do.

Next, the scanning speed of the reflected light on the flat screen will be described with reference to FIGS. As shown in FIG. 14, the scanning unit 2, strictly speaking, the light reflecting member 21 (not shown) of the scanning unit 2 is located at a distance L from the flat screen SC1 when the carriage 8 is not moving. It is in. For example, the scanning unit 2 reflects the incident light C by the light reflecting member 21, and scans the reflected light D in a predetermined direction (longitudinal direction (lateral direction in FIG. 14)) of the flat screen SC1. Here, when the light reflecting member 21 is not swinging, the scanning position of the reflected light D is X _0, and the position of the carriage 8 in the Z-axis direction in FIG. 14 is Z ₀ . Further, the rocking angle θ of the light reflecting member 21 when scanning from the scanning position X ₀ to one direction side (left side in FIG. 14) is a positive angle, and the other direction side (right side in FIG. 14) from the scanning position X ₀ . The swing angle θ of the light reflecting member 21 when scanned to) is a negative angle.

FIG. 15 is a graph showing an example of the swing angle of the light reflecting member. In the example shown in FIG. 14, the vibration system SI of the optical device 1 (light reflecting member 21) is swung at a predetermined frequency (frequency), scanning light reflected D scanning position on the flat screen SC1 from X ₀ When the reciprocating scanning is performed between the scanning position X ₁ and the scanning position X ₂ (X ₀ → X ₁ → X ₀ → X ₂ → X ₀ → X ₁ →...), As shown in FIG. The swing angle θ of the member 21 changes with time as a sine function (θ = sin (t)). In this case, although not shown, the speed ω ₁ of the swing angle θ changes with time by a cosine function (ω ₁ = dθ / dt = cos (t)).

As in the first embodiment, the scanning position x on the flat screen SC1 and the scanning speed v ₁ before changing the scanning speed by the carriage 8 are expressed by the above-described equations (1) and (2), respectively. Can do.

FIG. 16 is a graph showing an example of the position of the carriage. The carriage 8 shown in FIG. 14 changes the spatial position of the scanning unit 2 in order to change the scanning speed v ₁ of the reflected light on the flat screen SC1. That is, the carriage 8 corresponds to a specific example of changing means in the present invention.

The control circuit 4 shown in FIGS. 4 and 5 controls the carriage 8 so that the scanning speed changed by the carriage 8 (hereinafter referred to as the changed scanning speed) v ₂ becomes a predetermined speed. Specifically, the control circuit 4 controls the carriage 8 so that the time change of the distance L cancels the time change of the scanning speed v ₁ before the change.

That is, in Expression (2) representing the scanning speed v ₁ before the change, if the distance L is changed by the time t, the time change of the portion ({1 / (cos θ) ² }) that changes by the time t is offset. The changed scanning speed v ₂ can be set to a predetermined speed. Therefore, as shown in FIG. 16, the control circuit 4 moves the carriage 8 on which the scanning unit 2 is installed in the Z-axis direction in FIG. For example, the scanning speed v ₁ before the change can be lowered by bringing the carriage 8 closer to the flat screen SC1 and shortening the distance L as during the time t ₂ t ₃ . Further, for example, the scanning speed v ₁ before the change can be increased by moving the carriage 8 away from the flat screen SC1 and increasing the distance L as during the time t ₃ t ₄ .

FIG. 17 is a graph showing an example of the scanning speed changed by the carriage. As a result of the movement of the carriage 8 as shown in FIG. 16, as shown in FIG. 17, the scanning speed v ₂ changed by the carriage 8 becomes constant or substantially constant while periodically changing the direction (direction).

  In the present embodiment, the case where the optical device scans the reflected light D as the scanning surface is the flat screen SC1. However, the present invention is not limited to this. Good.

Thus, according to the optical device 1 in the present embodiment, the scanning unit 2 is moved by the carriage 8 so as to change the distance between the scanning unit 2 and the flat screen SC1. Accordingly, for example, the scanning unit 2 moves so as to change the distance L between the scanning unit 2 and the flat screen SC1 in accordance with the swinging motion of the light reflecting member 21, and thus the changed scanning on the flat screen SC1. the speed v ₂ can be easily set to a predetermined speed. Thereby, when the incident light C having a constant light amount is incident on the light reflecting member 21, the brightness of the reflected light D on the flat screen SC1 can be easily made constant or substantially constant.

  Further, according to the optical device 1 in the present embodiment, the changing means is the carriage 8 in which the scanning unit 2 is installed and approaches the flat screen SC1 or moves away from the flat screen SC1. Thereby, for example, the scanning unit 2 can be easily changed so that the distance L between the scanning unit 2 and the flat screen SC1 is changed by moving the carriage 8 in the vertical direction (Z-axis direction in FIG. 14) of the flat screen SC1. Can be moved. The carriage 8 is provided with a light source unit 9 that allows incident light C to enter the light reflecting member 21 of the scanning unit 2. Thus, when the carriage 8 moves, the scanning unit 2 (light reflecting member 21) and the light source unit 9 move together, so that the incident light C from the light source 9a can easily enter the light reflecting member 21. Can do.

<Optical scanning device>
(First embodiment)
FIG. 18 shows a first embodiment of an optical scanning device according to the present invention. Note that the same components as those of the first to third embodiments of the optical device according to the present invention described above are denoted by the same reference numerals, and description thereof is omitted.

  FIG. 18 is a schematic diagram illustrating the configuration of the first embodiment of the optical scanning device according to the present invention. As shown in FIG. 18, the optical scanning device 119 includes the optical device 1 according to the present invention, light sources 191, 192, and 193 of three colors of R (red), G (green), and B (blue), and a cross dichroic. A prism (X prism) 194, a galvanometer mirror 195, and a fixed mirror 196 are provided. The optical device 1 scans the reflected light in the longitudinal direction (lateral direction, X-axis direction in FIG. 18) of the external screen 197.

  In such an optical scanning device 119, light of each color is irradiated from the light sources 191, 192, 193 to the optical device 1 (the light reflecting member 21) via the cross dichroic prism 194. At this time, the red light from the light source 191, the green light from the light source 192, and the blue light from the light source 193 are combined by the cross dichroic prism 194. The light reflected by the light reflecting member 21 (three colors of combined light) is reflected by the galvanometer mirror 195, then by the fixed mirror 196, and irradiated on the screen 197.

  At that time, the reflected light reflected by the light reflecting member 21 by the operation of the optical device 1, for example, the swinging of the light reflecting member 21 around the axis A and the rotation of the scanning unit 2 around the axis A is reflected on the screen 197. Scanning (main scanning) is performed in the longitudinal direction (lateral direction, X-axis direction in FIG. 18). On the other hand, as the galvano mirror 195 rotates about the axis B, the reflected light reflected by the light reflecting member 21 is scanned (sub-scanned) in the short direction (vertical direction, Y-axis direction in FIG. 18) of the screen 197. . In addition, the intensity of light output from the light sources 191, 192, and 193 of each color changes according to image information received from a host computer (not shown).

  In the present embodiment, the planar screen 197 is shown as the scanning surface on which the optical scanning device 119 scans the reflected light. However, the present invention is not limited to this, and as described above, a multi-screen having two or more surfaces is used. There may be.

  Further, the changing means of the optical device 1 is not limited to the case where the actuator 3 or the motor 7 is used, but may be a carriage 8.

  Thus, according to the optical scanning device 119 in the present embodiment, for example, the means (first scanning means) for scanning the reflected light in the longitudinal direction (lateral direction, X-axis direction in FIG. 18) of the screen 197 is described above. The optical device 1 according to the present invention. Thereby, the scanning speed of the reflected light in the longitudinal direction (main scanning direction) of the screen 197 can be set to a predetermined speed. Here, when the reflected light is scanned in the longitudinal direction of the screen 197, the same predetermined time (in order to increase the deflection angle (swing angle) of the light reflecting member 21 as compared with the case of scanning in the short direction) 1 / frequency (frequency)), the scanning speed needs to be increased. As a result, the change in the scanning speed of the reflected light in the longitudinal direction of the screen 197 becomes larger, and the difference in brightness depending on the scanning position tends to increase. Therefore, by setting the scanning speed of the reflected light in the longitudinal direction of the screen 197 (main scanning direction) to a predetermined speed, it is possible to reduce the difference in brightness depending on the scanning position in the longitudinal direction of the screen 197, and excellent scanning characteristics. The optical scanning device 119 having the above can be realized.

(Second Embodiment)
FIG. 19 shows a second embodiment of the optical scanning device according to the present invention. Note that the same components as those of the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted.

  The difference between the second embodiment and the first embodiment is that the optical device 1B according to the present invention described above is provided instead of the galvanometer mirror 195.

  FIG. 19 is a schematic diagram illustrating a configuration in the second embodiment of the optical scanning device according to the present invention. As shown in FIG. 19, the optical scanning device 120 includes an optical device 1A that scans reflected light in the longitudinal direction of the screen 197 (lateral direction, X-axis direction in FIG. 19), and the longitudinal direction of the screen 197 (lateral direction, diagram). And an optical device 1A that scans the reflected light in the X-axis direction in FIG.

  That is, the reflected light reflected by the light reflecting member 21 due to the operation of the optical device 1A, for example, the swinging of the light reflecting member 21 around the axis A and the rotation of the scanning unit 2 around the axis A is the length of the screen 197. Scanning (main scanning) is performed in the direction (lateral direction, X-axis direction in FIG. 19). On the other hand, the reflected light reflected by the light reflecting member 21 due to the operation of the optical device 1B, for example, the swinging of the light reflecting member 21 around the axis B and the rotation of the scanning unit 2 around the axis B is short of the screen 197. Scanning (sub-scanning) is performed in the hand direction (vertical direction, Y-axis direction in FIG. 19).

  As described above, according to the optical scanning device 120 of the present embodiment, for example, the means (second scanning means) that scans the reflected light in the short direction (vertical direction, Y-axis direction in FIG. 19) of the screen 197. This is the optical device 1B according to the present invention described above. Thereby, the scanning speed of the reflected light in the short direction (sub-scanning direction) of the screen 197 can be set to a predetermined speed. Thereby, even in the short direction of the screen 197, the difference in brightness depending on the scanning position can be reduced, and the optical scanning device 120 having further excellent scanning characteristics can be realized.

<Image forming apparatus>
The above-described optical scanning device 119 or optical scanning device 120 according to the present invention is preferably applied to, for example, an image forming apparatus provided with a screen on which an image is projected or a multi-surface projector having two or more surfaces, an imaging display, or the like. be able to. Note that the image forming apparatus according to the present invention has substantially the same configuration as the optical scanning device 119 or the optical scanning device 120 described above, and therefore illustration and description thereof are omitted.

  As described above, the image forming apparatus according to the present embodiment includes the optical scanning device 119 or the optical scanning device 120 according to the present invention described above. Thereby, for example, in the longitudinal direction of the screen, the difference in brightness depending on the scanning position can be reduced, and excellent scanning characteristics are obtained. Thereby, a high-resolution image can be formed, and an image forming apparatus having excellent drawing characteristics can be realized.

  In addition, you may replace the structure of each above-mentioned embodiment, or may replace some components. The configuration of the present invention is not limited to the above-described embodiment, and various modifications may be made without departing from the scope of the present invention.

  DESCRIPTION OF SYMBOLS 1,1A, 1B ... Optical device, 2 ... Scanning part, 3 ... Actuator, 4 ... Control circuit, 7 ... Motor, 8 ... Carriage, 9 ... Light source part, 21 ... Light reflection member, 26 ... Support member, 27 ... Frame Part, 28 ... shaft member, 119, 120 ... optical scanning device, A ... shaft, SC1 ... flat screen

Claims (12)

A light reflecting member that reflects light; and a support member that supports the light reflecting member so as to be swingable about a predetermined axis. The light reflecting member is reflected by the light reflecting member by swinging. A scanning unit capable of scanning reflected light on the surface to be scanned;
An optical device comprising: changing means for changing a spatial position of the scanning unit with respect to the scanned surface in order to change a scanning speed of the reflected light in a predetermined direction on the scanned surface. The optical device according to claim 1, further comprising a control unit that controls the changing unit such that the scanning speed changed by the changing unit becomes a predetermined speed. A scanning unit support member for supporting the scanning unit;
The optical device according to claim 1, further comprising: a light source unit that causes the light to be incident on the light reflecting member. The optical device according to any one of claims 1 to 3, wherein the changing unit rotates the scanning unit around the predetermined axis. The optical device according to claim 4, wherein the changing unit is a piezoelectric actuator. The optical device according to claim 4, wherein the changing unit is a linear actuator. The optical device according to claim 4, wherein the changing unit is a motor. The optical device according to claim 3, wherein the changing unit moves the scanning unit so as to change a distance between the scanning unit and the surface to be scanned. The optical device according to claim 8, wherein the changing unit is a moving body in which the scanning unit and the light source unit are installed, approaching the scanned surface, or moving away from the scanned surface. First scanning means for scanning the reflected light in a first direction;
The optical scanner according to claim 1, wherein the first scanning unit is the optical device according to claim 1. Further comprising second scanning means for scanning the reflected light in a second direction;
The optical scanning apparatus according to claim 10, wherein the second scanning unit is the optical device according to claim 1. An image forming apparatus comprising the optical scanning device according to claim 10.

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