JPH10268220A - Optical deflecting device and multi-beam scanning device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the influence of a vibration factor such as disturbance by providing a vibration suppressing means for suppressing the vibration of an optical deflecting member between a support means and a holding means. SOLUTION: Compression coil springs 31a and 31b which have relatively weak compressing forces are inserted penetrating a yoke 24 and provided with low-friction members 30a and 30b made of, for example, 'TeflonR' on their bobbin-23 sides, and those low-friction members 30a and 30b and the bobbin 23 are in contact with each other. On the other sides of the compression coil springs 31a and 31b, stoppers 32a and 32b are provided across a stopper 32a. The bobbin 32 is pressed from the right and left with the elastic forces of the compression coil springs 31a and 31b, which are used for contacting the bobbin 23, so the load for deflecting a mirror 20 is reduced to suppress the vibration of the mirror 20 due to disturbing vibration while a driving current is held small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical deflecting device for deflecting light such as a laser beam by slightly displacing an optical deflecting member, and to a multi-beam scanning device using the same.

[0002]

2. Description of the Related Art In recent years, the use of light deflecting devices has increased due to the development of various devices using laser beams and the like. For example, a laser printer is an output device that can output an arbitrary number of sheets according to image or document information, but is equipped with an optical deflecting device because it is necessary to align a laser beam with a target with high accuracy. The configuration and function of a laser beam scanning device of this type of laser printer will be described with reference to FIG.

FIG. 5 shows a laser beam scanning apparatus for writing a laser beam on a photosensitive drum according to document information in a laser printer or a copying machine having a laser printer in a recording section. Is a multi-beam scanning device having the following.

In FIG. 5, reference numerals 1a and 1b denote laser emission sources, which use semiconductor laser diodes. These are pulse width modulated according to the image information to be recorded and flicker. The diffused light emitted from the laser light sources 1a and 1b is converted into parallel light by the finite lenses 2a and 2b. The laser beam that has passed through the finite lenses 2a and 2b is a galvano mirror 3a whose reflection angle can be arbitrarily changed by an electric signal.
3b. The two deflected laser beams are combined by the half mirror 4 on the surface of the photosensitive drum 10 so as to have the same pitch as the printer resolution. For example, if the resolution is 600 [dpi], the pitch is 42
[Μm].

The two combined laser beams simultaneously scan the surface of the photosensitive drum 10 by a polygon mirror 5 composed of an octahedral polygon mirror rotating at a high speed. The polygon mirror 5 is driven to rotate by a polygon motor 6 in the direction of the arrow. The two laser beams La and Lb scanned by the polygon mirror 5 pass through the f-θ lens 11 so as to form an image on the surface of the photosensitive drum 10, and scan in the main scanning direction (the direction of arrow S). On the scanning start side of the laser beam scanning range that does not cover the image area of the photosensitive drum 10,
A reflection mirror 12 for guiding a laser beam to a sensor 13 for detecting the position of the laser beam in the main scanning direction and the position in the sub-scanning direction is provided.

The sensor 13 has two laser beams La,
Just like Lb is focused on the surface of the photosensitive drum 10, it is installed at a position where the laser beams La and Lb are focused on the sensor 13. Image recording on the surface of the photosensitive drum 10 is performed in synchronization with a position detection signal of the two laser beams La and Lb in the scanning direction by the sensor 13. That is, the laser beam modulation is started in accordance with the image video signal after a predetermined time from the main scanning direction detection signal of the sensor 13. As a result, the image on the photosensitive drum surface is correctly aligned in a direction perpendicular to the laser beam scanning. In this figure, the sensor 13
And a control circuit for performing laser modulation for image recording in synchronization with the detection signal according to image video data is omitted.

The pitch of the two laser beams La and Lb in the direction perpendicular to the scanning direction on the surface of the photosensitive drum 10 (sub-scanning direction) is set to be the same as the printer resolution. The pitch of the laser beam is required to have a pitch accuracy of several microns or less so that the recording quality does not deteriorate. However, the laser beam is expanded about 20 to 60 times from the laser emission source to the photosensitive drum 10, and since the laser emission sources 1a and 1b are independently mounted on the housing, only adjustment at the time of mounting is performed. Therefore, it is impossible to maintain the pitch accuracy of the laser beam.

Therefore, the sensor 13 and the detection circuit 14 use the photosensitive drum 10 for the two laser beams La and Lb.
An image formation position on the surface is detected, and a deviation from a set value is obtained.
Based on the deviation signal, the control circuit 15 generates a control signal for controlling the galvanometer mirrors 3a and 3b for deflecting the laser beam imaging position arranged in each laser beam optical path. This control signal is fed back to the galvanomirror driving circuit 16 to control the deflection angle of the galvanomirror to keep the image position of the laser beam at a predetermined value, thereby accurately maintaining the pitch between the laser beams. The galvanometer mirrors 3a and 3b rotate in the direction in which the laser beam moves in the sub-scanning direction.

FIG. 6 is a perspective view, FIG. 7 is a three-sided view, and FIG. 8 is an exploded perspective view of the galvanometer mirrors 3a and 3b. A mirror 20 for deflecting the laser beam is adhered to a leaf spring 21, and a bobbin 23 is adhered to a side of the leaf spring 21 opposite to a side to which the mirror 20 is adhered. The coil 26 is bonded, and the leaf spring 21 is a galvanomirror body 2 also serving as a yoke.
4 are fixed by leaf spring retainers 25a and 25b.
Torsion springs (torsion bars) 22a and 22b are provided on both sides of the leaf spring 21 in the longitudinal direction, so that the mirror can rotate in the direction of arrow R.

When a current flows through the coil 26, an electromagnetic force is generated between the coil 27 and the magnet 27 provided on the magnet fixing plate 28, and the mirror 20 rotates in the direction of arrow R. Specifically, in the magnetic circuit shown in the lower right part of FIG. 7, the magnetic lines of force coming out of the N pole of the magnet 27 are directed to the yoke 24, and the magnetic lines of force divided right and left by the yoke as shown by the arrow B are along the yoke. It is configured to return to the south pole of the magnet 27 after turning around half way around. When a current is applied to the coil 26 in this state, the linear portion of the coil on the N-pole side and the linear portion of the coil on the S-pole side receive an electromagnetic force in the vertical direction, but in opposite directions.

Therefore, since the leaf spring 21 is fixed to the yoke 24, as a result, the leaf spring 21 rotates about the torsion bars 22a and 22b, which are torsion springs, as a center axis, and the mirror 20 also rotates in the direction of arrow R. become.
The rotation direction can be changed by changing the direction in which the current flows, and the rotation angle can be changed in proportion to the current value. Further, the mirror 20 can maintain the deflection angle by holding the current.

FIG. 9 is a view schematically showing the shape of the light receiving surface of a sensor 13 for measuring the position of the laser beam on the surface of the photosensitive drum 10. The sensor has a plurality of light receiving surfaces 200 formed by photodiodes. Here, the light receiving units 201, 202, 203, 204, and 205 are arranged on one chip.
The sensor 13 was constituted by the photodiode formed with.

A current flows by irradiating a laser beam in a state where a bias is applied between a cathode and an anode to a terminal connected to each light receiving section, and the current value changes depending on the laser light amount. The light receiving units 202 and 203 are for detecting an image forming position of the first laser beam La in the sub-scanning direction. The rectangular light receiving surfaces are opposed to each other with a gap of about 0.01 [mm]. The laser beam scans over the two light receiving sections, and it is possible to detect how much the laser beam deviates from the gap center of each light receiving section.

A detection signal corresponding to a deviation from the gap center is transmitted to the laser beam L via the control circuit 15 described above.
drive circuit 16 for galvanomirror 3a that deflects optical axis a
Is controlled so that the laser beam La always passes through the gap center between the light receiving units 202 and 203. The same control is performed for another laser beam Lb. In this case, opposing light receiving units 204 and 205 are provided with a gap of 0.01 [mm] for detecting the laser beam sub-scanning position, and the gap center is defined as the gap center of the light receiving unit pair 202 and 203 for detecting the laser beam La. From 0.042 [mm]. By controlling the laser beam Lb to always pass over the gap center of the light receiving units 204 and 205, the dot pitch of the laser beam La and Lb is 0.04 when the laser resolution is 600 [dpi].
It is set to be equal to 2 [mm].

The light receiving section 201 detects the timing of passage of each laser beam in the main scanning direction, and performs laser modulation for image recording in synchronization with a signal obtained by the light receiving section. However, there is the following problem when the laser beam is scanned in the above configuration.

That is, when a galvano mirror as an optical deflecting device is mounted on a copying machine, disturbance vibration is generated in the copying machine. Feeding device (AD
F) Vibration during operation, vibration in the printer unit due to the rotation of the polygon motor and photosensitive drum, and other vibrations of several cooling fans when removing paper. These vibrations cause the galvanomirror to vibrate, resulting in stable and high quality. Image recording may not be possible. In the case of using a multi-beam, each galvanomirror may vibrate at a different phase, resulting in a more distorted image.

[0017]

As described above, in the conventional light deflecting device, various devices or systems on which the light deflecting device is mounted, for example, a copying machine or the like, are provided with members causing many disturbances. Therefore, the optical deflection device vibrates under the influence of disturbance, and as a result, there is a problem that, for example, in a copying machine, an output image may be deteriorated.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide an optical deflector which is not affected by vibration factors such as disturbances and a multi-beam scanning device using the same.

[0019]

In order to achieve the above object, in an optical deflecting device according to the present invention, an optical deflecting member having a reflecting surface for reflecting light, and an optical deflecting member which holds the optical deflecting member and holds the optical deflecting member. Support means for rotatably supporting the deflecting member;
Holding means for holding the support means, driving means for rotating and driving the support means, provided between the support means and the holding means, for suppressing vibration of the light deflecting member. And vibration suppression means.

In particular, it is desirable that the vibration suppressing means is an elastic body whose one end is supported by the supporting means and the other end is supported by the holding means, and the elastic body is a compression coil spring or a leaf spring. More preferably, it is at least one selected from a rubber body, a flexible printed circuit board.

Preferably, the vibration suppressing means is a viscoelastic body filled between the supporting means side and the holding means side.
More preferably, it is at least one selected from a silicone gel having a magnetic substance and a magnetic fluid.

Further, in the multi-beam scanning device according to the present invention, a plurality of laser light sources, a plurality of finite lenses for respectively converting the laser beams emitted from these laser light sources into parallel light, A light deflecting member provided with a reflecting surface for supporting the light deflecting member and supporting means for rotatably supporting the light deflecting member;
Holding means for holding the support means, and driving means for rotating the support means, and a plurality of deflecting means provided to deflect the laser beam in predetermined directions, respectively. Image recording by scanning on a recording medium using an optical unit including a polygon mirror having a function of forming an image so that a plurality of laser beams deflected by the deflecting unit scan at a constant speed on a predetermined image plane. In the multi-beam scanning apparatus for performing the above, a vibration suppressing means provided between the supporting means and the holding means constituting the deflecting means and for suppressing the vibration of the light deflecting member is provided.

[0023]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an optical deflecting device according to the present invention. In the embodiments, the same components as those of the conventional configuration shown in FIG. 5 are denoted by the same reference numerals, and detailed description thereof will be omitted.

(First Embodiment) FIG. 1 is a schematic view showing an optical deflecting device according to a first embodiment of the present invention.
A mirror 20 as a deflecting member for deflecting light such as a laser beam is attached to a leaf spring 21, and a bobbin 23 is attached to a side of the leaf spring 21 opposite to the side on which the mirror 20 is attached. The coil 26 is mounted inside the bobbin 23.

The leaf spring 21 is fixed to a galvanomirror body 24 also serving as a yoke by leaf spring retainers 25a and 25b. Torsion springs (torsion bars) 22a and 22b are provided on both sides of the leaf spring 21 in the longitudinal direction.
Thereby, the mirror 20 is rotatable in a direction indicated by an arrow R (referred to as a turning direction) shown in FIG. Then, as described in detail with reference to FIG. 8, when a current is applied to the coil 26, an electromagnetic force is generated between the magnet 26 and the magnet 27 provided on the magnet fixing plate 28, and the mirror 20 rotates in the rotation direction. Move.

The rotation direction can be changed by changing the direction in which the current flows, and the rotation angle can be changed in proportion to the current value. Further, the mirror 20 can maintain the deflection angle by holding the current.

Reference numerals 31a and 31b denote compression coil springs having a relatively low compression force, which are inserted through the yoke 24. Low friction members 30a and 30b made of, for example, Teflon are provided on the bobbin 23 side of the compression coil springs 31a and 31b. The low friction members 30a and 30b and the bobbin 23
Is in contact with Stoppers 32a, 32b are connected to the other one of the compression coil springs 31a, 31b via the yoke 24.
Is provided.

With this configuration, the bobbin 23 is pressed from the left and right sides in the figure by the elastic force of the compression coil springs 31a and 31b, and the contact with the bobbin 23 is made using the low friction members 30a and 30b. Mirror 2
The load for deflecting 0 is small, and the mirror 20 can be suppressed from vibrating due to disturbance vibration while keeping the drive current small.

In the above embodiment, the pair of compression coil springs 31a and 31b are provided so as to press from both sides of the bobbin 23. However, the compression coil springs 31a and 31b are configured to press the bobbin 23 to one side with one compression coil spring. May be. Also, the configuration using the elastic force of the compression coil springs 31a and 31b has been described. However, as a component for obtaining the elastic force, a plate spring other than the compression coil spring is used, or the elastic force is obtained by filling a rubber material. It may be configured as follows.

(Second Embodiment) FIG. 2 is a schematic view showing an optical deflecting device according to a second embodiment of the present invention.
Hereinafter, the same portions as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. Only the portions having different configurations will be described.

The second embodiment is different from the first embodiment in that a vibration suppressing means for suppressing vibration is replaced with a compression coil spring by using a flexible printed circuit board. That is.

That is, 33a and 33b are flexible printed circuit boards which are formed thin and have elasticity.
One end of the flexible printed circuit boards 33a, 33b abuts the bobbin 23, and the other end of the flexible printed circuit board 33a, 33b is inserted through the yoke 24 through the yoke 24.
b. With flexible printed circuit boards,
The flexible printed circuit board is previously deformed into a corrugated shape so that the bobbin 24 can be pressed, and is disposed.

The flexible printed circuit boards 33a, 33
3b, wiring for applying a current to the coil 26 attached to the bobbin 23 is arranged. One end of the wiring is electrically connected to the coil 26, guided along the flexible printed board, and Is connected to an external power supply through the yoke 24.

By adopting such a configuration, the bobbin 23 is pressed from the left and right sides in the figure by the elastic force generated by deforming the flexible printed circuit boards 33a and 33b in advance, so that the mirror 20 vibrates. Can be suppressed.

(Third Embodiment) FIG. 3 is a schematic view showing an optical deflecting device according to a third embodiment of the present invention.
Hereinafter, the same portions as those in FIGS. 1 and 2 are denoted by the same reference numerals, and the description thereof will be omitted. Only different portions will be described.

The third embodiment differs from the first embodiment in that a vibration suppressing means for suppressing vibration is filled with a viscoelastic body instead of a compression coil spring or a flexible printed circuit board. That is, the configuration used in the above is adopted.

In the figure, reference numerals 29a and 29b denote silicone gels as an example of a viscoelastic body, which are filled in a gap between the yoke 24 and the bobbin 23 and are held by surface tension. Silicone gel has low viscosity at the time of injection, but becomes hard enough to be used as a damping agent by heating at, for example, 100 ° C. for about 1 hour or leaving it at room temperature for several tens of hours.

The silicone gels 29a and 29b form a minute gap between the yoke 24 and the bobbin 23, for example, 0.1 to 0.5.
In order to fill the micro gap, a liquid material discharging device such as a dispenser is used to fill the gap using the silicone gel filling grooves (holes) 34a and 34b provided in the yoke 24. doing. The grooves (holes) 34a and 34b for injecting the silicone gel are formed along the wall surface of the yoke 24, that is, along the minute gap between the yoke 24 and the bobbin 23 as shown in the drawing to the vicinity of the center of the yoke 24 in the height direction in the figure. When formed at this position, a predetermined amount of silicone gel is injected from a dispenser before attaching the magnet fixing plate 28.

The silicone gel injection groove (hole) 34
The a and b may be formed, for example, so as to penetrate the yoke 24. In this case, a predetermined amount of silicone gel can be injected from the dispenser even after the magnet fixing plate 28 is attached.

As described above, the silicone gels 29a, 29
When a current is applied to the coil 26 in a state in which b is filled in the minute gap between the yoke 24 and the bobbin 23, the mirror 20 rotates in the direction perpendicular to the paper of the drawing with the torsion bars 22a and 22b as rotation centers. Gel 29a,
Bobbin 23 to which coil 26 sandwiching 29b is bonded
Is moved, and the yoke 24 is stationary, so that the disturbance vibration is absorbed by the silicone gels 29 a and 29 b from the magnet mounting plate 28 via the yoke 24, so that the mirror 20 is not affected.

In the above description, an example of filling with silicone gel has been described, but a viscoelastic material other than silicone gel may be filled. For example, silicone for heat dissipation may be filled in order to efficiently radiate heat generated by the coil 26 to the outside via the yoke 24. As the heat-dissipating silicone, paste-like silicone oil compound having high thermal conductivity, liquid silicone rubber, silicone rubber sheet and the like can be used. Specifically, for example, heat-dissipating silicone (product of Toshiba Silicone Co., Ltd.) Name: TSE3
380, TSE3280G) and the like.

As described above, the gap between the yoke 24 and the bobbin 23 is a space that originally hinders heat conduction. However, by filling the heat-dissipating silicone having a high thermal conductivity, disturbance vibration is generated from the magnet mounting plate 28. In addition to being absorbed by the heat-dissipating silicone via the yoke 24 and not affecting the mirror 20, the heat of the coil 26 can be transferred to the outside via the heat-dissipating silicone and the yoke 24 to dissipate the heat. it can.

(Fourth Embodiment) FIG. 4 is a schematic diagram showing an optical deflecting device according to a fourth embodiment of the present invention.
Hereinafter, the same portions as those in FIGS. 1 to 3 are denoted by the same reference numerals, and the description thereof will be omitted. Only different portions will be described.

The fourth embodiment is different from the first embodiment in that a vibration suppressing means for suppressing vibration is filled with a viscoelastic body having magnetism. It is adopted. The configuration of FIG. 4 is based on the silicone gel 29 filled in the gap between the yoke 24 and the bobbin 23 of FIG.
A magnetic material, for example, iron pieces 34a and 34b are mixed in the a and 29b so as to adhere to the outside of the bobbin 23.

As described above, the silicone gels 29a, 29
By adopting a configuration in which a magnetic material such as iron pieces 34a and 34b is mixed into the magnet 27b, the iron pieces 34a and 34
b is always attracted, and the disturbance force can be suppressed by the suction force. Therefore, the two types of disturbance vibration suppressing means of the silicone gels 29a and 29b and the iron pieces 32a and 32b can be simultaneously operated, and the vibration suppressing effect can be significantly improved.

As another example of the viscoelastic body having magnetism, magnetic powder may be mixed into the silicone gels 29a and 29b instead of the iron pieces 34a and 34b. Further, a magnetic fluid may be used instead of the silicone gel. Since the viscosity of magnetic fluid is lower than that of silicone gel, the gap between the yoke and bobbin to be filled is smaller than that of filling with silicone gel, and the gap is held in a small gap by the surface tension of the magnetic fluid. Although it depends on the type of the gap and the type of the magnetic fluid, the gap is preferably, for example, about 50 μm to 0.1 mm. When the gap is reduced to this extent, even if the viscosity of the magnetic fluid is small, for example, the squeeze film effect is exhibited, so that the vibration suppressing effect can be sufficiently exhibited.

As described above, the first to fourth embodiments
By applying the optical deflector described in the embodiment to, for example, a multi-beam scanning device, and mounting the multi-beam device on a copying machine, the optical deflector can be operated by various disturbance vibrations generated in the copying machine. It is possible to avoid the influence and to perform stable high-quality image recording.

In the above-described embodiment, the galvano mirror in which the mirror as the light deflecting member is deflected by electromagnetic force as the light deflecting device has been described. It is apparent that the same effect can be obtained by driving the light deflecting member or by finely driving the light deflecting member using an air flow.

Further, in the above-described embodiment, the coil 26 for generating the rotational driving force is mounted on the bobbin 23 so as to rotate integrally with the mirror 20 (moving coil system). Instead, the magnet may be rotated integrally with the mirror, and the coil may be arranged on the fixed side (moving magnet system).

[0050]

As described above, according to the present invention, by providing the means for suppressing the vibration of the light deflecting member, it is possible to prevent the influence of various disturbance vibrations and the like, and to achieve a stable operation. Drive control of the light deflecting member can be performed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a first embodiment of an optical deflection device according to the present invention.

FIG. 2 is a cross-sectional view for explaining a second embodiment according to the light deflecting device of the present invention.

FIG. 3 is a cross-sectional view for explaining a third embodiment according to the light deflecting device of the present invention.

FIG. 4 is a sectional view for explaining a fourth embodiment of the light deflecting device of the present invention.

FIG. 5 is a perspective view illustrating a conventional multi-beam scanning device.

FIG. 6 is a perspective view illustrating a galvanomirror as an optical deflection device according to a conventional multi-beam scanning device.

FIG. 7 is a three-view drawing for explaining a galvanomirror as an optical deflecting device in a conventional multi-beam scanning device.

FIG. 8 is a perspective view illustrating a galvanomirror as an optical deflection device according to a conventional multi-beam scanning device.

FIG. 9 is a schematic diagram showing a light receiving section of a laser beam imaging position detecting sensor according to the conventional and the present invention for a multi-beam scanning apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 laser emission source 2 finite lens 3 galvanometer mirror 4 half mirror 5 polygon mirror 10 photosensitive drum 11 f-θ lens 12 mirror 13 imaging position detecting sensor 20 mirror (light deflecting member) 21 spring 23 bobbin (support means) 24 yoke (Holding means) 26 Coil (driving means) 27 Magnet (driving means) 29 Silicone gel (vibration suppressing means) 31 Compression coil spring (vibration suppressing means) 33 Flexible printed circuit board (vibration suppressing means) 200 Laser light receiving element

Claims (6)

[Claims] 1. A light deflecting member having a reflecting surface for reflecting light, supporting means for holding the light deflecting member and rotatably supporting the light deflecting member, and holding the supporting means Holding means for driving, a driving means for rotationally driving the supporting means, and a vibration suppressing means provided between the supporting means and the holding means for suppressing vibration of the light deflecting member. A light deflecting device comprising: 2. An optical deflecting device according to claim 1, wherein said vibration suppressing means is an elastic body whose one end is supported by said supporting means and whose other end is supported by said holding means. 3. An optical deflecting device according to claim 1, wherein said vibration suppressing means is a viscoelastic body filled between said supporting means and said holding means. 4. The elastic body includes a compression coil spring, a leaf spring,
3. The light deflecting device according to claim 2, wherein the light deflecting device is at least one selected from a rubber body and a flexible printed board. 5. The light deflecting device according to claim 2, wherein the viscoelastic body is at least one selected from a silicone gel, a silicone for heat dissipation, a silicone gel having a magnetic body, and a magnetic fluid. apparatus. 6. A plurality of laser light sources, a plurality of finite lenses for respectively converting laser beams emitted from these laser light sources into parallel light, and a light deflecting member having a reflecting surface for reflecting light. Supporting means for holding the light deflecting member and rotatably supporting the light deflecting member; holding means for holding the supporting means; and driving means for rotating the supporting means. A plurality of deflecting means for deflecting each of the laser beams in a predetermined direction, and a plurality of laser beams deflected by these deflecting means for scanning a predetermined image plane at a constant speed. A multi-beam scanning device that performs image recording by scanning on a recording medium using an optical unit including a polygon mirror having an image forming function; Provided between stages and the holding means, the multi-beam scanning apparatus which is characterized in that a vibration suppression means for suppressing vibration of the optical deflector.