JP5099021B2 - Optical scanning device, non-contact optical scanning control mechanism, and image forming apparatus - Google Patents

Description

  The present invention relates to a technique using optical scanning, for example, an optical scanning device, a non-contact optical scanning control mechanism, and an image forming apparatus.

  An optical scanner is known as an example of an optical device that performs drawing using optical scanning in a laser printer or the like. The optical scanner can be created by processing a silicon substrate using, for example, MEMS (Micro Electro Mechanical Systems) technology. Such an optical scanner projects an image or video on a plane (screen) by performing optical scanning (hereinafter referred to as “XY scanning”) in two axes (for example, the X axis and the Y axis). Can be displayed.

  However, when the surface (screen) on which an image or video is projected is a spherical surface or curved surface in a three-dimensional shape such as a sphere, a hemisphere, or a cylinder, the XY scanning may be inefficient. For example, when XY scanning is performed on a hemispherical screen as shown in FIG. 7, light is scanned not only in the screen but also in an area outside the screen, as indicated by the hatched portion in FIG. In this case, the light scanned outside the screen represented by the hatched portion is wasted and inefficient.

  Therefore, as one of the methods for performing efficient optical scanning even on a three-dimensional screen, instead of XY scanning, optical scanning in the polar coordinate (r-θ) direction (hereinafter referred to as “r-θ scanning”). ") Is also considered. The r-θ scan is possible by, for example, a combination of rotating the optical scanner around a certain rotation axis (θ direction) and one-dimensional scanning in the direction along the rotation axis (r direction). It becomes.

  Here, when driving power is supplied to the optical scanner, since the optical scanner rotates around the rotation axis, there is a limitation in the way to provide wiring. For example, if the wiring is provided over the part that rotates and the other fixed part, the wiring is entangled due to the rotational movement, which may hinder the rotational movement of the optical scanner or damage the wiring.

  Therefore, it is conceivable to supply drive power to the optical scanner in a non-contact manner. As an example of a technique for performing power transmission in a non-contact manner, there is a technique proposed by Patent Document 1 below. In Patent Document 1, a video camera is installed on a rotating body in order to take a picture of the surroundings using a video camera, and drive power is supplied (transmitted) to the rotating body side by electromagnetic induction by a magnetic field generating coil. It is described that this is performed in a non-contact manner.

JP 9-91584 A

  However, the above-described prior art requires at least two coils, a magnetic field generating coil and a current generating coil. Therefore, there is a possibility that the space required for coil arrangement becomes large.

  One of the objects of the present invention is to reduce the size of the structure for controlling the optical scanning, and thus to reduce the size of the optical scanning device and / or the image forming apparatus. Another object of the present invention is to improve the efficiency when performing optical scanning control in a non-contact manner.

  In addition, the present invention is not limited to the above-described object, and other effects of the present invention can be achieved by the functions and effects derived from the respective configurations shown in the embodiments for carrying out the invention which will be described later. It can be positioned as one of

  According to one aspect of the optical scanning device of the present invention, a light source that outputs a light beam, the light beam can be reflected at a variable angle with respect to the optical axis of the light beam, and parallel to the optical axis of the light beam. A mirror that is rotatable about a rotation axis; a magnet that is provided on the mirror so as not to interfere with the incidence of the light beam; and the magnet that is disposed so that the optical axis of the light beam passes through the inside. A coil for supplying an electromagnetic field.

  Further, according to one aspect of the non-contact light scanning control mechanism of the present invention, the light beam from the light source can be reflected at a variable angle with respect to the optical axis of the light beam and rotated in parallel with the optical axis of the light beam. A non-contact optical scanning control mechanism of an optical scanning device comprising a mirror rotatable about an axis, and a magnet provided on the mirror so as not to prevent incidence of the optical beam, A coil for supplying an electromagnetic field to the magnet, the optical axis being disposed so as to pass through the inside.

  Here, the coil may be provided on a member having a hollow structure, and the light beam may pass through a hollow portion of the member and enter the mirror.

  Further, a part or all of the members may be a magnetic material. Furthermore, the magnet and the coil may be provided at positions facing each other about the optical axis.

  According to another aspect of the image forming apparatus of the present invention, the light beam is emitted by controlling the reflection angle of the mirror with an electromagnetic field generated by the coil.

The figure which shows typically the structural example of the optical scanning device of one Embodiment. FIG. 2 is a perspective view schematically illustrating the structure of the optical scanner illustrated in FIG. 1. FIG. 3 is a schematic cross-sectional view in a direction orthogonal to a rotation axis of the optical scanner illustrated in FIG. 2. The figure which shows typically the structural example of the back surface of the movable plate illustrated to FIG.2 and FIG.3. FIG. 2 is a perspective view schematically showing a configuration in which an example of a non-contact light scanning control mechanism of this embodiment is applied to the optical scanning device illustrated in FIG. 1. FIG. 6 is a schematic cross-sectional view when the optical scanning device illustrated in FIG. 5 is cut along a plane along the rotation axis of the turntable. The schematic diagram which shows the structure in the case of projecting an image on a hemispherical screen. The figure which shows the scanning range in the projection shown in FIG.

  Embodiments of the present invention will be described below with reference to the drawings. However, the embodiment described below is merely an example, and there is no intention to exclude various modifications and technical applications that are not explicitly described below. That is, the present invention can be implemented with various modifications without departing from the spirit of the present invention. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. Further, the drawings are schematic for the following description, and specific dimensions and the like should be determined in relation to the following description. In addition, there may be a portion where the dimensional relationships and ratios are different between the drawings.

(One embodiment)
FIG. 1 is a perspective view schematically illustrating a configuration example of an optical scanning device 10 according to an embodiment. The optical scanning device 10 illustrated in FIG. 1 exemplarily outputs an optical scanner 20, a rotating body (rotary base) 30 provided with the optical scanner 20, and a laser beam (light beam) L used for optical scanning. A laser light source 40 is provided.

  The turntable 30 exemplarily has a donut shape having a hollow portion 301 having a predetermined radius around the rotation axis Θ. The turntable 30 can rotate 360 degrees or more around the rotation axis Θ by a drive circuit such as a motor. However, the turntable 30 may be a hollow motor itself.

  The hollow portion 301 allows the light beam L output from the laser light source 40 to pass therethrough. Therefore, the radius (cross-sectional area) of the hollow portion 301 may be equal to or larger than the diameter (cross-sectional area) of the light beam L. For example, a through-hole through which the light beam L can pass may be provided in the rotating shaft (motor shaft) of a hollow motor as the turntable 30. For example, a direct drive motor, a stepping motor, a servo motor, a DC motor, or the like can be used as the motor or the hollow motor that drives the turntable 30. In addition, as a method (drive mechanism) for rotating the turntable 30, as described above, a drive force is applied to the outer periphery (circumference) of the turntable 30 in addition to the method of applying a drive force to the rotation shaft of the turntable 30. The method of giving can also be applied. For example, a method may be used in which the circumference of the turntable 30 is formed into a gear shape, and the motor and the gears on the circumference of the turntable 30 are engaged to rotate.

  As will be described later, the optical scanner 20 includes a mirror (one-dimensional scanning mirror) 24 (see FIG. 2) that enables one-dimensional optical scanning. The mirror 24 is provided on the turntable 30 so that the light beam L that has passed through the hollow portion 301 of the turntable 30 can enter the mirror surface.

  Illustratively, the optical scanner 20 (mirror 24) is supported by a support member 201 provided on the surface of the turntable 30 except for the hollow portion 30, and the mirror 24 is positioned on the optical path (optical axis) of the light beam L. So that it is positioned and fixed.

  In other words, the mirror 24 can rotate about the rotation axis Θ parallel to the optical axis of the light beam L while receiving the light beam L that has passed through the hollow portion 301 of the turntable 30. . The optical scanner 20 has a rotation axis R (see FIG. 2) in a direction intersecting with the rotation axis Θ, for example, a direction perpendicular to the rotation axis Θ, and is indicated by an arrow r in FIG. Rotation (uniaxial scanning) within a predetermined angle range in the direction is possible.

  2 and 3 show a configuration example of the optical scanner 20. FIG. 2 is a schematic perspective view of the optical scanner, and FIG. 3 is a schematic cross-sectional view in a direction orthogonal to the rotation axis R of the optical scanner 20.

  The optical scanner 20 illustrated in FIG. 2 is an example of an electromagnetically driven optical scanner. For example, the base 21 in which the recessed space is formed, the movable plate 22, and the above-described description provided on the surface of the movable plate 22. And a movable mirror substrate 25 having a magnet 23 (see FIGS. 3 and 4) provided on the back surface of the movable plate 22.

  For example, a glass substrate, a silicon substrate, or the like can be used for the base 21, and a recess (space) that allows vibration (rotation) of the movable plate 22 is provided. The recesses can be provided, for example, by etching the base 21 or by forming spacer portions at both ends of the base 21.

  The movable mirror substrate 25 is exemplarily further movable through a pair of torsion bars (a torsion spring which is an example of an elastic member) 27a and 27b provided at both ends of the movable plate 22, and the torsion bars 27a and 27b. Support frame fixing portions 29 a and 29 b that support the plate 22 are provided. Such a movable mirror substrate 25 can be formed, for example, from a silicon single crystal substrate (thin plate) using a MEMS microfabrication technique.

  The mirror 24 reflects the light beam L incident from the laser light source 40 through the hollow portion 301 of the turntable 30. The reflected light beam L can be used for optical scanning. The optical scanner 20 may be a mirror capable of scanning not only in one dimension but also in two dimensions (two axes) or more.

  The magnet 23 shown in FIGS. 3 and 4 is, for example, a bar magnet having an N pole and an S pole, and the N pole and the S pole in a direction orthogonal or substantially orthogonal to the torsion bars 27a and 27b (rotation axis R). Is arranged to be located. Magnetic lines (static magnetic fields) from the N pole to the S pole are formed in the space including the movable plate 22 by the magnet 23. When another magnetic field is applied to the static magnetic field from the outside, forces in opposite directions are generated at both ends of the magnet 23, so that the rotational force can be applied to the movable plate 22. As a result, the rotation angle (swing angle) of the movable plate 22, that is, the reflection angle of the mirror 24 can be controlled. The method of applying the magnetic field will be described later with reference to FIGS.

  In FIG. 1, the light beam L output from the laser light source 40 is incident on the mirror 24, so that the reflected light of the mirror 24 can be used for optical scanning. Therefore, for example, the laser light source 40 is disposed on the opposite side of the optical scanner 20 with the rotary table 30 interposed therebetween so that the optical path of the light beam L from the laser light source 40 to the optical scanner 20 is along the rotation axis Θ. Has been. As a result, the light beam L output from the laser light source 40 passes through the hollow portion 301 of the turntable 30 along the rotation axis Θ of the turntable 30 and enters the mirror 24 of the optical scanner 20.

  As long as the light beam L can pass through the hollow portion 301 of the turntable 30 and enter the mirror 24, the arrangement position of the laser light source 40 may not be the rotation axis Θ or the vicinity thereof. For example, one or a plurality of mirrors may be provided on the optical path of the light beam L, and the laser light source 40 may be arranged in a direction different from the direction along the rotation axis Θ of the turntable 30.

Next, the operation of the optical scanning device 10 using the above-described optical scanner 20 will be described.
The light beam L output from the laser light source 40 passes through the hollow portion 301 of the turntable 30 and enters the mirror 24 of the optical scanner 20. As described above, the movable plate 22 of the optical scanner 20 is rotated around the rotation axis R (see FIG. 2) and rotated in the direction indicated by the arrow r in FIG. The light beam L is scanned in the direction of the arrow S shown in FIG.

  Further, by rotating the turntable 30 about the rotation axis Θ, the light beam L reflected by the mirror 24 is scanned in the direction of the arrow θ shown in FIG. That is, the mirror 24 can reflect the light beam L at a variable angle with respect to the optical axis of the light beam L, and can rotate about a rotation axis Θ parallel to the optical axis of the light beam L.

  By combining the rotation around the rotation axis R of the optical scanner 20 and the rotation around the rotation axis Θ of the turntable 30 as described above, light is applied to the entire cylindrical screen centering on the rotation axis Θ. The beam L can be scanned. Therefore, it is possible to efficiently project an image or video on the entire cylindrical screen.

  In addition, as illustrated in FIG. 1, the laser light source 40 is disposed on the opposite side of the rotary table 30 with respect to the optical scanner 20, and the light beam L passes through the hollow portion 301 of the rotary table 30 and is light. By making the light incident on the mirror 24 of the scanner 20, it is not necessary to provide the wiring of the laser light source 40 and the turntable 30 between the projection screen and the optical scanner 20.

  Furthermore, since the laser light source 40 can be provided at a position away from the rotary table 30 and the optical scanner 20 that rotate, the laser light source 40 can be an individual unit that does not require rotational driving. Therefore, it is not necessary to apply an extra load to the turntable 30. In addition, it is possible to suppress the drive signal of the laser light source 40 from being affected by noise that may be caused by the rotating table 30 and the optical scanner 20 that rotate, so that stable driving of the laser light source 40 can be realized.

  Furthermore, since the laser light source 40 can be disposed on the opposite side of the optical scanner 20 and the projection screen with the rotary table 30 interposed therebetween, the laser light source 40 can be given a degree of freedom, and thus the degree of freedom in designing the optical system can be increased. Can be improved.

(Non-contact light scanning control mechanism)
Next, a method (mechanism) for controlling the rotation (optical scanning) of the movable plate 22 (mirror 24) of the optical scanner 20 provided on the rotary table 30 will be described with reference to FIGS. FIG. 5 is a perspective view schematically showing a configuration in which an example of the non-contact optical scanning control mechanism of the optical scanner 20 of this embodiment is applied to the optical scanning device 10 illustrated in FIG. FIG. 6 is a schematic cross-sectional view when the optical scanning device 10 illustrated in FIG. 5 is cut along a plane along the rotation axis Θ of the turntable 30.

  As illustrated in FIGS. 5 and 6, the non-contact light scanning control mechanism of this example includes, for example, a coil fixing member 31 and a coil 311 provided on the coil fixing member 31. Reference numeral 50 represents a power supply circuit that supplies power to the coil 311.

  When the coil 311 is supplied with electric power (current) from the power supply circuit 50, the coil 311 generates an electromagnetic field corresponding to the received current value. For example, the coil 311 can be provided along the outer peripheral surface of the coil fixing member 31. For example, a predetermined length of conductive wire (wire) may be wound along the outer peripheral surface of the coil fixing member 31, or the coil pattern may be patterned along the outer peripheral surface of the coil fixing member 31.

  For example, the coil fixing member 31 can be provided on the opposite side of the surface of the turntable 30 from the surface on which the optical scanner 20 is provided such that the axis thereof coincides with the rotation axis Θ of the turntable 30. . The structure for rotatably supporting the turntable 30 can be realized by a combination with various known bearings such as ball bearings. However, the coil fixing member 31 is not fixed to the turntable 30 and does not rotate even if the turntable 30 rotates.

  As an example of the structure for supporting the turntable 30, as shown in FIG. 6, a bearing (for example, thrust bearing) 32 is used to fix the turntable 30 to one surface of the bearing 32 and the other of the bearings 32. It is mentioned that the surface is fixed to the turntable support member 33. As the turntable support member 33, a plate-like individual member can be used. Further, the coil fixing member 31 can be fixed by being fitted into the bearing 32. With such a structure, the turntable 30 can be rotated while the coil fixing member 31 is not rotated but fixed.

  Further, the coil fixing member 31 is illustratively a hollow cylindrical body having a through hole 312 through which the light beam L can pass. The through hole 312 only needs to have a diameter (cross-sectional area) through which the light beam L can pass. In other words, the through hole 312 includes a part of the optical path (optical axis) of the light beam L. The diameter of the through hole 312 may be different from or the same as the diameter of the hollow portion 301 of the turntable 30. The cross-sectional shape of the through hole 312 does not have to be circular as long as it can pass the light beam L, and may be polygonal.

  The diameters of the hollow portion 301 of the turntable 30 and the through holes 312 of the coil fixing member 31 may be different from each other. The light beam L output from the laser light source 40 can pass through the through hole 312 of the coil fixing member 31 and the hollow portion 301 of the turntable 30, and can enter the optical scanner 20 (mirror 24). .

  In the above-described configuration, when the electromagnetic field generated by the coil 311 acts on the magnetic field formed by the magnet 23 provided on the back surface of the movable plate 22 of the optical scanner 20, rotational force is generated in the movable plate 22 and the movable plate 22 is movable. The rotation angle of the plate 22, that is, the deflection angle (reflection angle) of the mirror 24 can be controlled.

  For example, an electromagnetic field (alternating current magnetic field) is generated in the coil 311 during a period in which current is supplied (turned on) from the power supply circuit 50 (alternating current power source) to the coil 311, and this alternating magnetic field acts on the static magnetic field formed by the magnet 23. Thus, one end of the magnet 23 is attracted to or separated from the coil 311. As a result, the movable plate 22 vibrates about the torsion bars 27a and 27b as the rotation axis R. On the other hand, in a period in which no current is supplied (off), the AC magnetic field disappears, and the movable plate 22 returns to the original position by the restoring force of the torsion bars 27a and 27b, which are elastic members.

  When such an on / off operation is performed at high speed according to the cycle of the AC power supply, the movable plate 22 is in a resonance state at a specific frequency (switching frequency or drive frequency), and the deflection angle of the movable plate 22, that is, the mirror 24, is increased. Stable at a specific angle. In this way, the optical scanner 20 is used in a resonance state where the deflection angle is stable.

  For example, when the light beam L output from the laser light source 40 enters the mirror 24, the reflected light of the mirror 24 can be used as a light beam for optical scanning. In this example, the optical scanner 20 is not limited to one that can perform one-dimensional (one-axis) scanning, but may be one that can perform two-dimensional (two-axis) scanning or more.

  In order to efficiently perform the rotation control of the movable plate 22 (mirror 24) by the electromagnetic field of the coil 311 described above, the axis of the coil 311 and the central portion of the magnet 23 have the same axis (for example, the rotation axis Θ). It is good to arrange on top. Further, it is preferable that the mutual distance is as close as possible within a range not preventing the rotation of the turntable 30. Alternatively or additionally, a part of the coil fixing member 31 (for example, a part where the coil 311 is provided) or the whole material is made of a magnetic material such as iron or ferrite, and the coil fixing member 31 is replaced with the coil 311. By using the magnetic core (magnetic core), the strength of the electromagnetic field generated by the coil 311 may be increased.

  As described above, the magnet 23 is provided on the movable plate 22 (mirror 24) of the optical scanner 20, and the electromagnetic field of the coil 311 provided on the coil fixing member 31 is applied to the static magnetic field formed by the magnet 23. Thus, the reflection angle (optical scanning) of the mirror 24 can be controlled in a non-contact manner. Therefore, it is possible to control the reflection angle of the mirror 24 in a non-contact manner without using an additional coil on the turntable 30 side. Therefore, the space required for coil arrangement can be minimized and the optical scanning device 10 can be downsized.

  In addition, by using a part or all of the coil fixing member 31 provided with the coil 311 as a magnetic body, the coil fixing member 31 functions as a magnetic core of the coil 311, so that the electromagnetic field strength generated by the coil 311 is increased. Thus, the reflection angle control of the mirror 24 can be performed more efficiently and reliably.

(Image forming device)
The optical scanning device 10 having the non-contact optical scanning control mechanism described above can be applied to an image forming apparatus such as a projector or an imaging display whose projection screen has a three-dimensional shape such as a cylindrical shape or a hemispherical shape. That is, the light beam L can be emitted and scanned by controlling the reflection angle of the mirror 24. The injection destination can be a three-dimensional screen. As a result, an image forming apparatus having excellent drawing characteristics can be realized in a space-saving manner.

DESCRIPTION OF SYMBOLS 10 ... Optical scanning device, 20 ... Optical scanner, 21 ... Base | substrate, 22 ... Movable plate, 23 ... Magnet, 24 ... Mirror (one-dimensional scanning mirror), 30 ... Rotating stand, 31 ... Coil fixing member, 32 ... Bearing ( (Thrust bearing), 33 ... rotating table support member, 40 ... laser light source, 50 ... power supply circuit, 301 ... hollow portion, 311 ... coil, 312 ... through-hole, Θ, R ... rotating shaft, L ... laser beam (light beam)

Claims (7)

A light source that outputs a light beam;
A mirror that is capable of reflecting the light beam at a variable angle with respect to the optical axis of the light beam, and that is rotatable about a rotation axis parallel to the optical axis of the light beam;
A magnet provided on the mirror so as not to interfere with the incidence of the light beam;
A coil for supplying an electromagnetic field to the magnet, disposed so that an optical axis of the light beam passes inside;
An optical scanning device comprising: The coil is provided on a member having a hollow structure,
The optical scanning device according to claim 1, wherein the light beam passes through a hollow portion of the member and enters the mirror. An optical scanning device comprising: a mirror capable of reflecting a light beam from a light source at a variable angle with respect to an optical axis of the light beam and rotatable about a rotation axis parallel to the optical axis of the light beam. Non-contact light scanning control mechanism of
A magnet provided on the mirror so as not to interfere with the incidence of the light beam;
A coil for supplying an electromagnetic field to the magnet, disposed so that an optical axis of the light beam passes inside;
A non-contact light scanning control mechanism. The coil is provided on a member having a hollow structure,
The non-contact light scanning control mechanism according to claim 3, wherein the light beam passes through a hollow portion of the member and enters the mirror.   The non-contact light scanning control mechanism according to claim 4, wherein a part or all of the member is a magnetic material.   The non-contact light scanning control mechanism according to claim 3, wherein the magnet and the coil are provided at positions facing each other with the optical axis as an axis. An image forming apparatus comprising the optical scanning device according to claim 1,
An image forming apparatus that emits the light beam by controlling a reflection angle of the mirror by an electromagnetic field generated by the coil.

Images