JPH1164769A - Light deflecting device and beam scanner using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light deflecting device and a beam scanner using the device capable of recording a high-quality image having no image deterioration by improving the efficiency of a magnetic circuit. SOLUTION: This light deflecting device is provided with a mirror 20 for reflecting light, a yoke 24 for turnably holding the mirror 20 through a leaf spring 21, a coil 26 and a magnet 27 for turning and driving the mirror 20 with respect to the yoke 24, a magnet fixing plate 28 holding the yoke 24, and positioning pins 31a and 31b partially inserted in the yoke 24 so as to be positioned with respect to the yoke 24. The magnet 27 forms the magnetic circuit in the yoke 24. The pins 31a and 31b are constituted of magnetic body so as not to disturb the magnetic circuit formed in the yoke 24.

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 minutely displacing an optical deflecting member and a 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 capable of outputting an arbitrary number of images or document information in page units, and a light deflection device is used as a laser beam scanning device of a conventional laser printer of this type.

[0003] A typical configuration of a galvanomirror used in a multi-beam scanning device as a typical light deflector will be described below. FIG. 12 is a perspective view showing the configuration of a galvanomirror, FIGS. 13A, 13B, and 13C are three views, and FIG. 14 is an exploded perspective view.

In FIGS. 12 to 14, a mirror (light deflecting member) 20 for deflecting a laser beam is elastically supported by an elastic support so that the mirror itself is finely driven. The elastic support is a leaf spring (a supporting member) having a portion to be attached to the mirror 20, a portion to be attached to the yoke 24 as a frame, and two torsion springs or torsion bars 22a, 22b connecting the two portions. ) 21 and a mirror 2
0 is adhered. The reflection surface of the mirror 20, that is, the deposition surface, is provided on the side of the mirror 20 opposite to the side where the leaf spring 21 is located.

The material of the leaf spring 21 is beryllium copper or stainless steel often used as a spring material, for example, SUS30.
4 is used. A bobbin 23 is adhered to a side of the leaf spring 21 opposite to the side to which the mirror 20 is adhered, and a coil 26 is adhered inside the bobbin 23. The leaf spring 21 is provided on a yoke (holding member) 24 made of a ferromagnetic material also serving as a frame, and a leaf spring presser 25a made of resin.
25b. That is, the leaf spring 21
Are screws (not shown) in screw holes 40a and 40b provided in the yoke 24, and holes 37a and 3 provided in the leaf spring 21.
7b and holes 41 provided in the leaf spring retainers 25a and 25b.
a, 41b.

The magnet 27 is bonded to a magnet fixing plate (base member) 28 made of a non-magnetic material. The magnet 27 is provided on the magnet fixing plate 28 in a screw hole (not shown) provided in the yoke 24 by a screw (not shown). Holes 39a, 39
b. The torsion bars 22a and 22b are provided on both sides in the longitudinal direction of the leaf spring 21, whereby the mirror 20 is rotatable in the direction of arrow R (see FIGS. 12 and 13C).

When an electric current flows through the coil 26, an electromagnetic force is generated between the coil 26 and the magnet 27 attached to the magnet fixing plate 28, and the mirror 20 rotates in the direction of arrow R.

More specifically, in FIG. 15, the magnetic lines of force coming out of the N-pole surface (magnetized surface) of the magnet 27 are directed to the yoke 24, and the magnetic lines of force divided right and left by the yoke 24 as shown by arrow B are shown in FIG. , And returns to the S pole surface (magnetized surface) of the magnet 27.

When a current flows through the coil 26 in this state, N
The linear portion of the coil 26 on the pole face side in the magnetic gap between the magnet 27 and the yoke 24 and the coil 2 on the S pole face side
6 receives the electromagnetic force in the vertical direction but in the opposite direction.

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 central axis.
The mirror 20 also rotates in the direction of arrow R. In addition,
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 rotation angle by holding the current.

In FIGS. 13 (a), 13 (b) and 13 (c), damping agents 29a and 29b such as silicone gel are provided in the gap between the yoke 24 and the bobbin 23 so that the mirror 20 does not vibrate due to disturbance vibration. Is filled.

[0012]

However, there are the following problems when a laser beam is scanned by the optical deflecting device having the above configuration.

That is, in FIG. 14, the magnet fixing plate 2
The positioning pins (positioning members) 31a and 31b are used to position the yoke 24 with respect to the magnet fixing plate 2.
8 are inserted into the positioning holes 38a, 38b and the positioning holes 33a, 33b of the yoke 24. However, since SUS304 or the like, which is a non-magnetic material, is conventionally used as the positioning pins 31a and 31b, the lines of magnetic force passing through the yoke 24 are obstructed, so that the efficiency of the magnetic circuit formed in the yoke 24 is reduced. There was a problem of getting worse.

In FIG. 15, the magnetic lines of force coming out of the N-pole surface of the magnet 27 are directed to the yoke 24, and the magnetic lines of force divided right and left by the yoke 24 as shown by the arrow B halfway around the yoke 24 on the opposite side. , And returns to the S pole surface of the magnet 27, but when the magnetic field lines coming out of the N pole surface go to the yoke 24, the area of the portion of the yoke 24 facing the N pole surface of the magnet 27 is reduced. Since the area of the magnet 27 is larger than the area of the N pole face, the lines of magnetic force spread toward the yoke 24. The same applies to the S pole surface side. Therefore, there is a problem that the magnetic flux density at the position of the coil 26 is reduced, and the efficiency of the magnetic circuit is deteriorated.

In FIG. 15, the magnetic lines of force coming out of the N-pole surface of the magnet 27 are directed to the yoke 24, and the magnetic lines of force divided right and left by the yoke 24 as shown by the arrow B form a half circumference along the yoke 24 to form the magnet 27. Return to the S pole surface, but without making a half turn, where there are protrusions 47a and 47b provided on the yoke 24 for filling with silicone gel for vibration countermeasures.
Magnetic lines of force returning to the magnet 27 may be generated. Therefore, there is a problem that a leakage magnetic flux is generated and the efficiency of the magnetic circuit formed in the yoke 24 is deteriorated.

As described above, in the conventional laser beam scanning device, the efficiency of the magnetic circuit of the galvanomirror as the light deflecting device is low, and the desired performance may not be obtained.

An object of the present invention is to provide an optical deflecting device and a beam scanning device using the same, which enable high-quality image recording without image deterioration by improving the efficiency of a magnetic circuit. is there.

[0018]

A first feature of the present invention is as follows.
A light deflecting member having a reflecting surface for reflecting light, a support member for supporting the light deflecting member, a holding member for holding the supporting member, and a device for rotating the light deflecting member with respect to the holding member. And a base member that supports the holding member, and a positioning member made of a magnetic material that positions the holding member with respect to the base member. In the first aspect of the present invention, it is preferable that the driving mechanism forms a magnetic circuit in the holding member. Preferably, the positioning member is made of a magnetic material so as not to disturb a magnetic circuit formed in the holding member.

A second feature of the present invention is that a light deflecting member having a reflecting surface for reflecting light, a supporting member for supporting the light deflecting member, a holding member for holding the supporting member and having an opening are provided. A driving mechanism that is disposed in the opening of the holding member and that includes a magnet and a coil for rotating and driving the light deflecting member with respect to the holding member,
An optical deflecting device characterized in that a first overhang is formed on a surface of the opening of the holding member facing the magnetized surface of the magnet. In the second aspect of the present invention, it is preferable that the first overhang portion has substantially the same area as the magnetized surface of the magnet. In addition, it is preferable that a second overhang made of a non-magnetic material protrudes from a surface of the opening of the holding member that does not face the magnetized surface of the magnet.

A third feature of the present invention is that a plurality of light sources, a plurality of light deflecting devices for deflecting light emitted from each of the light sources in a predetermined direction, and a light deflecting device by each of the light deflecting devices. In a beam scanning device including a scanning device that scans a predetermined image plane at a constant speed, each of the light deflecting devices includes a light deflecting member having a reflecting surface that reflects light, and a support member that supports the light deflecting member. A holding member that holds the support member, a driving mechanism that rotationally drives the light deflecting member with respect to the holding member, and a base member that supports the holding member.
A positioning member made of a magnetic material for positioning the holding member with respect to the base member. In the third aspect of the present invention, it is preferable that the driving mechanism forms a magnetic circuit in the holding member. Preferably, the positioning member is made of a magnetic material so as not to disturb a magnetic circuit formed in the holding member.

A fourth feature of the present invention is that a plurality of light sources, a plurality of light deflecting devices for deflecting light emitted from the respective light sources in a predetermined direction, and a light deflecting by the respective light deflecting devices are provided. In a beam scanning device including a scanning device that scans a predetermined image plane at a constant speed, each of the light deflecting devices includes a light deflecting member having a reflecting surface that reflects light, and a support member that supports the light deflecting member. A drive member configured to hold the support member and have an opening, and a magnet and a coil disposed in the opening of the support member for rotating the light deflecting member with respect to the holding member. A beam projection device having a mechanism, wherein a first overhang is formed so as to protrude from a surface of the opening of the holding member facing the magnetized surface of the magnet. In the fourth aspect of the present invention, it is preferable that the first overhang portion has substantially the same area as the magnetized surface of the magnet. In addition, it is preferable that a second overhang made of a non-magnetic material protrudes from a surface of the opening of the holding member that does not face the magnetized surface of the magnet.

According to the first and third aspects of the present invention,
Since the lines of magnetic force passing inside the holding member are not obstructed,
The efficiency of the magnetic circuit formed in the holding member can be improved.

According to the second and fourth aspects of the present invention,
Since the first overhanging portion is formed on the surface of the opening of the holding member facing the magnetized surface of the magnet, a decrease in the magnetic flux density and a leakage magnetic flux in the gap between the magnetized surface of the magnet and the holding member are prevented. It hardly occurs, so that the efficiency of the magnetic circuit formed in the holding member can be improved. In addition, since the second protrusion of the nonmagnetic material is formed so as to protrude on the surface of the opening of the holding member that does not face the magnetized surface of the magnet, the gap of the portion filled with the damping agent or the like is kept small. Leakage magnetic flux can be prevented, so that the efficiency of the magnetic circuit formed in the holding member can be improved.

[0024]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an optical deflecting device and a beam scanning device using the same according to the present invention.

First Embodiment FIG. 1 is a view showing a light deflecting device according to a first embodiment of the present invention. In FIG. 1, a mirror (light deflecting member) 20 for deflecting light such as a laser beam is attached to one surface of a leaf spring (supporting member) 21. A bobbin 23 is mounted on a side of the leaf spring 21 opposite to the side on which the mirror 20 is mounted, and a coil 26 that forms a driving mechanism together with a magnet 27 is mounted inside the bobbin 23.

In order to fix the leaf spring 21 to the yoke (holding member) 24 having an opening 24a at the center by screws, the leaf spring 21 is provided with holes 37a and 37b for screwing, and the yoke 24 is provided with a screw. Screw holes 35a and 35b corresponding to the holes 37a and 37b for stopping are provided.

The leaf spring 21 has a positioning hole 3.
6a, 36b, 36c, 36d are provided, and the yoke 24 is provided.
Similarly, positioning holes 34a, 34b, 34c, 3
4d is provided. Then, these pins are temporarily fixed to these positioning holes so as not to pass through the positioning pins 32a, 32b, 32c, and 32d, and then fixed by screws.

As described above, the positioning holes 36a, 36b, 36c, 36d provided in the leaf spring 21 and the yoke 2
4, positioning holes 34a, 34b, 34
positioning pins 32a, 32b, 3
By penetrating 2c and 32d, the leaf spring 21 is temporarily fixed to the yoke 24, so that the torsion bars 22a and 22b, which are torsion springs of the leaf spring 21, can be prevented from bending when screwed.

Screw hole 3 provided in leaf spring 21
7a, 37b and positioning holes 36a, 36b, 36
It is desirable to provide c and 36d at the positions as shown in FIG. That is, the screw holes 37a, 37b are arranged, for example, in line with the longitudinal direction of the torsion bars 22a, 22b, and the positioning holes 36a, 36 are arranged.
The b, 36c and 36d are arranged on both sides of the screw holes 37a and 37b and are spaced apart in a direction perpendicular to the longitudinal direction of the torsion bars 22a and 22b.

Then, the positioning holes 36a, 36b, 36c, 36d thus arranged and the screw holes 37a, 37b are aligned with each other to position the positioning pin 3
By temporarily fixing them with 2a, 32b, 32c, and 32d, the positioning pins 32a, 32b, 32c, and 32d come into contact with the positioning holes 37a, 37b, 37c, and 37d even when the screws are tightened in the assembly process. Therefore, the leaf spring 21 and the yoke 24 act as an integral part of the screw tightening, and the torsion bar 22a,
It is possible to prevent an unnecessary stress such as a twisting force from acting on 22b.

A positioning pin (positioning member) 31
Reference numerals a and 31b denote a yoke 24 and a magnet fixing plate (base member).
Positioning pins 31 are commonly used for positioning holes 33a, 33b of yoke 24 and positioning holes 38a, 38b of magnet fixing plate 28.
a, 31b, positioning can be performed.

Here, the positioning pins 31a, 31b
Is a magnetic material. That is, conventionally, as such positioning pins 31a and 31b, SU, which is a non-magnetic material, is used.
Although S304 and the like are used, in the first embodiment of the present invention, positioning pins of a magnetic material, for example, SUS405 or SU
A positioning pin made of a magnetic material typified by stainless steel such as S410 or carbon steel such as S15C is used.

Since the positioning holes 33a and 33b of the yoke 24 into which the positioning pins 31a and 31b are inserted are provided in the yoke 24 through which the magnetic force lines pass, the positioning of the non-magnetic material (for example, SUS304) is performed as in the related art. If pins were used, there was a possibility that the magnetic field lines forming the magnetic circuit would be obstructed. On the other hand, according to the first embodiment of the present invention, the efficiency of the magnetic circuit can be improved by making the positioning pins 31a and 31b magnetic.

The magnetic positioning pins 31a, 31a
As the material of 31b, the same material as yoke 24 or the same material as yoke 24 may be used.
Considering the hardness and workability of the material so as to function effectively as a and 31b, the stainless steel (for example, SU
It is desirable to use S405 or SUS410).
In the case of stainless steel, the workability for satisfying the positioning accuracy required for the positioning pins 31a and 31b, for example, the mirror finishing of the surfaces of the positioning pins 31a and 31b and the hardness required for the positioning pins 31a and 31b are sufficiently provided. It is possible to meet.

Second Embodiment FIG. 2 is a view showing a main part of an optical deflecting device according to a second embodiment of the present invention. Hereinafter, the same parts as those in FIG. A description thereof will be omitted, and only different components will be described. As shown in FIG. 2, in the second embodiment of the present invention, the opening 24 a of the yoke 24 has a surface facing the N-pole surface and the S-pole surface (magnetized surface) of the magnet 27 from the yoke 24. Protruding overhangs (first overhangs) 44a and 44b are provided.

The projecting portions 44a and 44b are formed so as to protrude from the yoke 24.
7 is smaller than the other portions by the thickness of the overhang portions 44a and 44b, that is, the magnetic gap is narrowed.

That is, the magnetic lines of force coming out of the N-pole surface of the magnet 27 are directed toward the overhanging portion 44a which is formed to protrude from the yoke 24 and reduces the magnetic gap. A half circumference along the yoke 24, the opposite side, and the return to the S pole surface of the magnet 27 through the overhang portion 44b.

As a result, unlike the conventional case having no overhang portion, the magnetic field lines do not spread and go to the yoke 24, and when the magnetic field lines B coming out of the N pole surface of the magnet 27 go to the yoke 24, The lines of magnetic force that proceed obliquely and the lines of magnetic force that proceed obliquely are mixed, and the lines of magnetic force that proceed obliquely pass through the inside of the yoke 24 and do not reach the surface of the yoke 24 that faces the S-pole surface of the magnet 27, and From leaking out of the magnet 27 and not returning to the S-pole surface of the magnet 27 can be avoided.

Therefore, according to the second embodiment of the present invention, the magnetic flux density in the gap between the N-pole surface and the S-pole surface of the magnet 27 and the yoke 24 and leakage magnetic flux hardly occur. The efficiency of the magnetic circuit formed in the yoke 24 can be improved.

In order to reduce the leakage magnetic flux, the surfaces of the overhang portions 44a and 44b facing the N-pole surface and the S-pole surface of the magnet 27 are, as shown in FIG. It is desirable to have substantially the same area as the S pole surface.

Third Embodiment FIG. 3 is a diagram showing a main part of an optical deflecting device according to a third embodiment of the present invention. Hereinafter, the same parts as those in FIG. A description thereof will be omitted, and only different components will be described.

As shown in FIG. 3, in the third embodiment of the present invention, the magnet 2 in the opening 24 of the yoke 24
Overhanging portions (second overhanging portions) 45a and 45b are formed on surfaces not facing the N-pole surface and the S-pole surface (magnetized surface) of No. 7, and the overhanging portions 45a and 45b are made of a non-magnetic material. The overhang portions 45a, 45b can be realized by, for example, integrally attaching the overhang portions 45a, 45b made of a non-magnetic material (eg, resin) to the yoke 24 with an adhesive or the like and projecting them.

Overhanging portions 45a, 45b of this non-magnetic material
Is provided for the following reason. In other words, the portion where the magnetic field lines from the magnet 27 do not pass through the mirror 20 due to disturbance vibration.
For example, damping agents 29a and 29b such as silicone gel (see FIG. 13B) are filled so as not to vibrate. Since the damping agent such as silicone gel has a better damping characteristic when the gap filled with the damping agent is smaller, it is necessary to narrow the gap between the yoke 24 and the bobbin 23.

As described above, the damping agents 29a, 29b
In order to fill the damping agent, it is necessary to narrow the gap between the yoke 24 and the bobbin 23. However, when the gap is narrowed, the flow of the lines of magnetic force forming the original magnetic circuit is narrowed to fill the damping agent. Leaks into the gap, which reduces the efficiency of the magnetic circuit.

Therefore, in the third embodiment of the present invention,
By making the overhang portions 45a and 45b provided for filling the damping agents 29a and 29b such as silicone gels into a non-magnetic material, as shown in FIG.
The magnetic lines of force B coming out of the N pole surface of No. 7 are projected portions 45a, 45
This eliminates the possibility that the magnetic field lines leak from b and return to the S-pole surface of the magnet 27, thereby preventing the leakage magnetic flux while keeping the gap small. Efficiency can be improved.

As shown in FIG. 3, the overhang portions 45a and 45b in the above-described third embodiment are the same as the overhang portions 44 of the magnetic material in the above-described second embodiment.
The efficiency of the magnetic circuit can be further improved by using it together with a and 44b.

Fourth Embodiment The light deflecting device according to the first to third embodiments described above is applied to, for example, a multi-beam scanning device shown in FIG.
By mounting this multi-beam scanning device in a copying machine, high-quality image recording without image deterioration can be performed. FIG. 4 shows a multi-beam scanning device mounted on a laser printer, a copying machine having a laser printer in a recording unit, etc., for writing a laser beam on a photosensitive drum in accordance with document information. The light deflecting device according to the first to third embodiments is replaced with a galvanomirror 3
a and 3b.

Although FIG. 4 shows a multi-beam scanning device having two laser light sources 1a and 1b as an example, a multi-beam scanning device having two or more laser light sources may be used. A similar description holds.

In FIG. 4, laser light emitting sources 1a, 1b
Are composed of semiconductor laser diodes, which are pulse width modulated according to the image information to be recorded and flicker. The diffused light emitted by the laser light emitting sources 1a and 1b becomes parallel light by the finite lenses 2a and 2b. Finite lens 2
The laser beams La and Lb that have passed through a and 2b have galvano mirrors 3 whose reflection angles can be arbitrarily changed by electric signals.
a, 3b. The two deflected laser beams La and Lb are combined by the half mirror 4 on the surface (predetermined image surface) of the photosensitive drum 10 so as to have the same pitch as the printer resolution. For example, if the resolution is 600 dp
In the case of i (dots per inch), the pitch is 42 μm.

The two combined laser beams La and L
b, the surface of the photosensitive drum 10 is simultaneously scanned by a polygon mirror (scanning device) 5 composed of an octahedral polygon mirror rotating at a high speed. The polygon mirror 5 is driven to rotate in the direction of arrow C by a polygon motor 6.

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, the laser beams La and Lb are directed toward a sensor 13 for detecting the positions of the laser beams La and Lb in the main scanning direction and the sub scanning direction. Is installed.

The sensor 13 has two laser beams La,
Just like Lb is focused on the surface of the photosensitive drum 10, the laser beam is placed on the sensor 13 at a position where the laser beams La and Lb are focused. The 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, in the laser light emitting sources 1a and 1b, the modulation of the laser beam 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 surface of the photosensitive drum 10 is correctly aligned in a direction orthogonal to the laser beam scanning. In FIG. 4, a control circuit for performing laser modulation for image recording in accordance with image video data in synchronization with the main scanning direction detection signal from the sensor 13 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 beams La and Lb is required to have a pitch accuracy of several microns or less so that the recording quality does not deteriorate. However, the laser beam L
a, Lb are the laser light sources 1a, 1b to the photosensitive drum 1
Since the laser emission sources 1a and 1b are independently mounted on the housing, the pitch accuracy of the laser beam can be maintained only by adjusting at the time of installation. Impossible.

Therefore, the sensor 13 and the detection circuit 14 use the photosensitive drum 1 of the two laser beams La and Lb.
The imaging position on the zero surface is detected, and a deviation from the set value is obtained. Based on the deviation signal, the control circuit 15 generates a control signal for controlling the galvanomirrors 3a and 3b for changing the laser beam imaging positions arranged in the optical paths of the respective laser beams La and Lb.

The control signal is supplied to the galvanomirror driving circuit 1
6, the rotation angle of the galvanometer mirrors 3a, 3b is controlled to keep the image forming position of the laser beams La, Lb at a predetermined value, thereby maintaining the pitch between the laser beams La, Lb with high accuracy. Galvanometer mirror 3a,
Reference numeral 3b rotates in a direction in which the laser beams La and Lb move in the sub-scanning direction.

FIG. 5 is a schematic diagram showing a light receiving surface of a sensor 13 for detecting a laser beam image forming position on the surface of the photosensitive drum 10.

The sensor 13 has a light receiving surface 200 formed by a photodiode (laser light receiving element). Here, five light receiving sections 20 are provided in one chip photodiode.
The sensor 13 is formed by forming 1, 202, 203, 204 and 205.

Each of the light receiving sections 201, 202, 203,
A current flows to the terminals connected to 204 and 205 by irradiating a laser beam with a bias applied between the cathode and the anode, and the current value changes depending on the amount of laser light. The light receiving units 202 and 203 are for detecting an image forming position of one laser beam La in the sub-scanning direction. The surfaces of the rectangular light receiving sections are opposed to each other with a gap of about 0.01 mm. Laser beam La is 2
By scanning over the two light receiving units 202 and 203, it is possible to detect how much the light receiving units 202 and 203 deviate from the gap center.

The detection signal corresponding to the 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 over the gap center between the light receiving units 202 and 203.

The same control is performed for another laser beam Lb. In this case, in order to detect the imaging position of the laser beam Lb in the sub-scanning direction, the light receiving units 204 and 20 facing each other with a gap of 0.01 mm are used.
5, and the gap center is set at a distance of 0.042 mm from the gap center of the light receiving units 202 and 203 for detecting the laser beam La. By controlling the laser beam Lb to always pass over the gap center of the light receiving units 204 and 205, the pitch of the laser beams La and Lb is adjusted to a printer resolution of 600 dpi.
Is set to be equal to the dot pitch of 0.042 mm corresponding to.

The light receiving section 201 detects the timing of passage of each of the laser beams La and Lb in the main scanning direction, and performs laser modulation for image recording in synchronization with a signal obtained by the light receiving section 201. You.

The numbers of the laser light sources 1a and 1b and the galvanometer mirrors 3a and 3b depend on the performance required for a printer or a copier equipped with a multi-beam scanning device.
As shown in the above, there are two sets, three or more sets, for example, four sets, which are set as needed.

As described above, by incorporating the light deflecting device according to the first to third embodiments as the galvanometer mirrors 3a and 3b into the multi-beam scanning device shown in FIG. Can be recorded.

The present invention is not limited to the above-described first to fourth embodiments. For example, in a drive mechanism for generating a rotational driving force, a coil 26 is used as an optical deflecting device. Instead, a so-called movable magnet system in which the magnet 27 is integrally joined to the mirror 20 while being arranged on the magnet fixing plate 28 and thereby the magnet 27 rotates integrally with the mirror 20 may be adopted.

In the above-described fourth embodiment, when the optical deflector is mounted on a copying machine or the like and used, the resonance frequency of the galvanomirrors 3a and 3b, which are optical deflectors, and the frequency of the copying machine or the like are different. When the rotation frequency of the motor being used coincides with the rotation frequency of an integral multiple or 1 / integral thereof, resonance occurs, and the galvanomirrors 3a, 3b
Is known to vibrate so that desired performance cannot be satisfied. In particular, since the polygon motor 6 provided in the same optical unit as the galvanometer mirrors 3a and 3b is closest to the galvanometer mirrors 3a and 3b, the rotation frequency of the polygon motor 6 and its integral multiple or 1 / integer rotation frequency are reduced. If the resonance frequency matches or is close to the resonance frequency of the galvanomirrors 3a and 3b, the polygon motor 6 and the galvanomirrors 3a and 3b may resonate.

FIG. 6 shows the rotation frequency and the rotation frequency of the polygon motor 6 disposed at the position closest to the galvanomirrors 3a and 3b as the light deflecting device, among a plurality of motors used in a copying machine equipped with the light deflecting device. The relationship between the rotation frequency of an integral multiple or a fraction of the integer and the amplitude of vibration at each rotation frequency is shown.

According to FIG. 6, when the polygon motor 6 rotates at an arbitrary constant rotation frequency, its rotation frequency f _m
It can be seen that the vibration peaks at the rotation frequency of an integral multiple of the rotation frequency or a fraction of the rotation frequency, and the vibration easily occurs. Here, the polygon motor 6
Against the rotational frequency f _m, the frequency f _{m 4} to the 4-fold
And a frequency f _{m1 / 4} up to _{１ ／,} but there is also a frequency at which a peak of vibration is likely to occur and a vibration is likely to occur in a wider magnification.

As described above, the polygon motor 6 has a vibration component caused by the rotation frequency, and the rotation frequency f
_m and a rotation frequency that is an integral multiple or a fraction of an integer thereof,
Galvanomirror 3a that is a frequency characteristic as shown in FIG. 7, occurs the resonance and the resonance frequency f _g of 3b coincide, it becomes impossible to accurately print the mirror 20 is vibrated greatly.

In this regard, the present inventors set the resonance frequency f _g of the galvanometer mirrors 3a and 3b as shown in FIG.
It has been confirmed that such an undesirable resonance can be avoided by setting the rotation frequency f _m of the polygon motor 6 and an integer multiple or a fraction of the rotation frequency ± 5% of the rotation frequency.

That is, assuming that the rotational frequency caused by the rotational frequency of the motor is f _mi , | f _g −f _mi | / f _g > 0.05 i =..., 1/4, 1/3, 1/2, 1,2,3,4, galvanomirror 3a so as to satisfy the ... conditions, by designing the resonance frequency f _g of 3b, it is possible to perform stable printing without resonance occurs.

In the above description, the rotational frequency of the polygon motor 6 has been described as an example of the disturbance vibration. However, other motors in the copying machine, for example, a motor for driving a photosensitive drum, a motor for driving a heat roller of a fixing machine, and a scanner The same holds for the motor for driving the carriage, the motor for transporting the paper, and the like.

Further, the same applies to the case where these motors rotate simultaneously at different rotational speeds. That is, FIG. 6 shows only the case of the polygon motor 6, but when a plurality of motors rotate at different rotation speeds, a graph of frequency characteristics is obtained by the number of motors. It has a vibration peak. In this case, it is possible to avoid the resonance is set galvanomirror 3a, the resonant frequency f _g of 3b outside the range of ± 5% of the rotational frequency and the first rotation frequency of an integer multiple or an integer fraction of the motors And stable printing can be performed.

[0074] Further, the motor not due to the rotation frequency, there is a resonance such as a motor own housing, by designing the resonance frequency f _g of the galvanometer mirror, including the frequency, to perform a more stable printing Can be.

On the other hand, in the above-described first to fourth embodiments, the galvanometer mirrors 3a and 3b have a structure in which the mirror 20 rotates when a current flows through the coil 26.
When a current is applied to the coil 26, Joule heat is always generated according to the coil resistance. When the coil 26 generates heat, the leaf spring 21
Since the torsion bars 22a and 22b may be deformed by thermal expansion, it is necessary to prevent heat generation as much as possible. The temperature rise of the coil 26 is determined by the material, the wire diameter, the number of turns (number of turns) of the coil 26, the load and the magnetic circuit, and is ultimately determined by the coil resistance and the current flowing through the coil 26. Therefore, it is necessary to design a galvanomirror that satisfies predetermined conditions so that the coil 26 does not generate heat.

Regarding this point, the present inventors made the material of the coil 26 copper, set the diameter of the coil 26 (wire diameter of the conductor system) in the range of 0.06 to 0.07 mm, and set the number of coil turns to 400 to 600. Turn range and coil resistance 70
It has been confirmed that the temperature rise of the coil 26 can be reduced by setting the range to 120Ω.

FIG. 8 shows two types of the case where the coil diameter is 0.06 mm, the case where the number of coil turns is 408 and the coil resistance is 79Ω, and the case where the number of coil turns is 540 and the coil resistance is 105Ω. The result of measuring the temperature of the coil 26 itself when a current having a value enough to actually rotate the mirror 20 is shown.

According to FIG. 8, in the case of 408 turns, the current value when the mirror 20 is displaced by 10 mrad, which is the maximum displacement angle, is about 0.055 A and the temperature rise is about 20
° C and the current value is about 0.038 for 540 turns.
A, the temperature rise is about 15 ° C., and deviates from the standard of temperature rise of the coil 26 (temperature rise ΔT ≦ 60 ° C.).
Is not high.

Fifth Embodiment FIGS. 9 and 10 are views for explaining a modification of the fixing method of the leaf spring 21 shown in FIG. 1. Hereinafter, the same parts as those in FIG. The description thereof will be omitted, and only different components will be described.

First, a first modification of the method of fixing the leaf spring 21 will be described with reference to FIG.

As shown in FIG. 9, the leaf spring holding member 42a
In FIG. 14, for example, positioning projections 43a and 43b are provided on a leaf spring retainer 25a shown in FIG. The other leaf spring holding member 42b is also the same as the leaf spring holding member 25b shown in FIG. 14 in which positioning projections 43c and 43d are provided.

The positioning projections 43a, 43b,
43c and 43d are positioning pins 32a and 3 shown in FIG.
2b, 32c, and 32d. The leaf spring holding members 42a and 42b are provided with positioning projections 43.
Screw holes 41a and 41b are provided between a and 43b or between the positioning projections 43c and 43d, respectively.

The positioning projections 43a, 43b, 43c, 43d of the leaf spring pressing members 42a, 42b are used instead of the positioning pins 32a, 32b, 32c, 32d shown in FIG. That is, the leaf spring holding member 42
a, 42b, positioning projections 43a, 43b, 43c,
43d are holes 36a, 36b for positioning the leaf spring 21;
36c, 36d and holes 34a for positioning the yoke 24,
The plate spring 21 is temporarily fixed to the yoke 24 by passing the plate springs through 34b, 34c, and 34d.

As described above, by temporarily fixing the leaf spring 21 and the yoke 24, the positioning pin 3 shown in FIG.
Similarly to the method using 2a, 32b, 32c, 32d,
Torsion bars 22a, 2 which are torsion springs of leaf spring 21
No stress such as an unnecessary twisting force is applied to the screw 2b when the screw is tightened, so that the torsion bars 22a and 22b can be prevented from bending at the time of screwing.

The leaf spring pressing members 42a and 42b are made of, for example, resin or the like, and are relatively light in weight and the like, and are disadvantageous in terms of driving force and the like as compared with the case of FIG. It is not going to be.

The positioning pins 32a, 32 shown in FIG.
When the leaf spring pressing members 42a and 42b shown in FIG. 9 are used, the leaf spring 21 can be pressed over the entire surface of the leaf spring pressing members 42a and 42b, as compared with the case where 2b, 32c and 32d are used. In addition, unnecessary movement of the leaf spring 21 at the time of temporary fixing can be effectively prevented.

The positioning pins 32a, 3 shown in FIG.
When the leaf spring pressing members 42a and 42b shown in FIG. 9 are used, the leaf spring pressing members 42a and 42b and the positioning projections 43a,
43b, 43c, and 43d are integrated with each other, so only by fitting the leaf spring holding members 42a, 42b, the positioning projections 43a, 43b or the positioning projections 43c,
43d can be passed through the positioning holes 36a, 36b or the positioning holes 36c, 36d of the leaf spring 21 at the same time, so that the positioning pins 32a, 32b, 32c,
The assembly process can be simplified as compared with the case where 32d is passed one by one.

Next, a second modification of the method of fixing the leaf spring 21 will be described with reference to FIG. As shown in FIG. 10, when the leaf spring 21 is fixed to the yoke 24, spot welding can be used as a method other than the screwing shown in FIG.

In this case, the positioning pins 32a, 32
b, 32c, and 32d are aligned with holes 36 for positioning the leaf spring 21.
a, 36b, 36c, 36d and the holes 34a, 34b, 34c, 34d for positioning the yoke 24, and then the spot welding holes 37 provided in the leaf spring 21.
The leaf spring 21 and the yoke 24 are welded by using a and 37b.

Thus, the leaf spring 21 can be fixed to the yoke 24 without using screws, and the torsion bars 22a and 22b, which are torsion springs, can be fixed so as not to bend.

As described above, according to the fixing method of the leaf spring 21 shown in FIG. 10, the positioning pins 32a, 32b, 32
After the leaf spring 21 is temporarily fixed to the yoke 24 by c and 32d, spot welding is performed to prevent unnecessary stress such as torsion force from acting on the torsion bars 22a and 22b of the leaf spring 21 and stabilize. An assembling process can be realized.

Sixth Embodiment FIG. 11 is a view showing an assembled state of the optical deflector shown in FIG. 1. Hereinafter, the same parts as those in FIG. Only different components will be described.

As shown in FIG. 11, the galvanomirror 3
For example, one side surface 44 of the yoke 24 is pressed against one side surface (side surface serving as a reference surface) 60a of an L-shaped positioning wall 60 provided on a base 45 of a multi-beam optical unit or the like, and a screw, a spring or the like is pressed. Positioning is performed by fixing with.

That is, one side surface 44 of the yoke 24 which comes into contact with the positioning wall surface 60 provided on the base 45 serves as a positioning surface. It is fixed by a method such as bonding.

Thus, the one side surface 44 of the yoke 24 on which the leaf spring 21 supporting the mirror 20 is mounted serves as a reference surface when the galvanometer mirror 3 is mounted on the base 45. Can be accurately positioned with respect to the base 45.

In the conventional assembling method, when assembling the galvanometer mirror 3 to the multi-beam optical unit, screws are passed through the recesses 42a and 42b shown in FIG. 13B and fixed to the base by screws or the like. It is difficult to accurately assemble the galvanomirror 3 to the base 45. In addition, it is necessary to adjust the assembly error by rotating the main body of the galvanometer mirror 3 while checking the position of the laser beam with the optical adjustment performed after the assembly, or performing fine adjustment while tilting the galvanomirror back and forth. Time is needed. In particular, since a plurality of laser beams are used in the multi-beam optical system, the optical adjustment time is required by the number of the galvanometer mirrors 3. However, according to the assembling method shown in FIG.
And the time for optical adjustment in the multi-beam optical system can be shortened.

[0097]

As described above, according to the present invention, since the lines of magnetic force passing through the inside of the holding member are not hindered, the efficiency of the magnetic circuit formed in the holding member can be improved.

Further, according to the present invention, since the first projection is formed so as to protrude on the surface of the opening of the holding member facing the magnetized surface of the magnet, the gap between the magnetized surface of the magnet and the holding member is formed. The magnetic flux density in the gap is hardly reduced and the leakage magnetic flux hardly occurs, so that the efficiency of the magnetic circuit formed in the holding member can be improved. In addition, since the second protrusion of the nonmagnetic material is formed so as to protrude on the surface of the opening of the holding member that does not face the magnetized surface of the magnet, the gap of the portion filled with the damping agent or the like is kept small. Leakage magnetic flux can be prevented, so that the efficiency of the magnetic circuit formed in the holding member can be improved.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view illustrating an optical deflecting device according to a first embodiment of the present invention.

FIG. 2 is a plan view illustrating a magnetic circuit of a galvanomirror as an optical deflecting device according to a second embodiment of the present invention.

FIG. 3 is a plan view illustrating a magnetic circuit of a galvanomirror as an optical deflecting device according to a third embodiment of the present invention.

FIG. 4 is a diagram for explaining a beam scanning device (multi-beam scanning device) according to a fourth embodiment of the present invention.

FIG. 5 is a schematic diagram showing a light receiving surface of a sensor for detecting a laser beam image forming position used in the multi-beam scanning device.

FIG. 6 is a graph showing frequency characteristics of a motor used in the multi-beam scanning device.

FIG. 7 is a graph showing frequency characteristics of a galvanomirror as an optical deflecting device.

FIG. 8 is a graph for explaining a relationship between a current value of a galvano mirror as an optical deflection device and a coil temperature.

FIG. 9 is a view for explaining a first modification of the method of fixing the leaf spring (support member) shown in FIG. 1;

FIG. 10 is a view for explaining a second modification of the method of fixing the leaf spring (support member) shown in FIG. 1;

FIG. 11 is a perspective view illustrating an assembled state of a galvanomirror as an optical deflecting device.

FIG. 12 is a perspective view illustrating a galvanomirror as an optical deflection device used in a conventional multi-beam scanning device.

FIG. 13 is a three-view drawing for explaining a galvanomirror as an optical deflection device used in a conventional multi-beam scanning device.

FIG. 14 is an exploded perspective view illustrating a galvanomirror as an optical deflection device used in a conventional multi-beam scanning device.

FIG. 15 is a plan view illustrating a magnetic circuit of a galvanomirror as an optical deflection device used in a conventional multi-beam scanning device.

[Explanation of symbols]

 1a, 1b Light source 3a, 3b Galvano mirror (light deflecting device) 5 Polygon mirror (scanning device) 20 Mirror (light deflecting member) 21 Leaf spring (supporting member) 24 Yoke (holding member) 24a Opening 26 Coil (drive mechanism) 27 Magnet (drive mechanism) 28 Magnet fixing plate (base member) 31a, 31b Positioning pin (positioning member) 44a, 44b (First) overhanging portion 45a, 45b (Second) overhanging portion

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tamane Takahara 1 Toshiba R & D Center, Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa

Claims (12)

[Claims] An optical deflecting member having a reflecting surface for reflecting light; a supporting member for supporting the optical deflecting member; a holding member for holding the supporting member; A light deflecting device comprising: a driving mechanism for rotationally driving; a base member for supporting the holding member; and a positioning member made of a magnetic material for positioning the holding member with respect to the base member. . 2. The optical deflecting device according to claim 1, wherein the driving mechanism forms a magnetic circuit in the holding member. 3. The optical deflecting device according to claim 2, wherein the positioning member is made of a magnetic material so as not to interfere with a magnetic circuit formed in the holding member. 4. A light deflecting member having a reflecting surface for reflecting light, a supporting member for supporting the light deflecting member, a holding member for holding the supporting member and having an opening, and the opening of the holding member. A driving mechanism comprising a magnet and a coil for rotating the light deflection member with respect to the holding member, wherein the driving mechanism includes a magnet and a coil, and the opening portion of the holding member faces a magnetized surface of the magnet. An optical deflecting device, wherein a first overhang is formed on a surface to be projected. 5. The optical deflecting device according to claim 4, wherein said first overhang portion has substantially the same area as a magnetized surface of said magnet. 6. A second overhanging portion made of a non-magnetic material protrudes from a surface of the opening of the holding member that does not face the magnetized surface of the magnet. 6. The light deflecting device according to 5. 7. A plurality of light sources, a plurality of light deflecting devices for deflecting light emitted from the respective light sources in a predetermined direction, and the light deflected by the respective light deflecting devices on a predetermined image plane at a constant speed. A beam scanning device including a scanning device for scanning, wherein each of the light deflecting devices holds a light deflecting member having a reflection surface that reflects light, a support member that supports the light deflecting member, and the support member A holding member, a driving mechanism for rotating the light deflection member relative to the holding member, a base member supporting the holding member, and a magnetic body for positioning the holding member with respect to the base member. A beam scanning device comprising: a positioning member; 8. The beam scanning device according to claim 7, wherein said drive mechanism forms a magnetic circuit in said holding member. 9. The beam scanning device according to claim 8, wherein said positioning member is made of a magnetic material so as not to obstruct a magnetic circuit formed in said holding member. 10. A plurality of light sources, a plurality of light deflecting devices for deflecting the light emitted from each of the light sources in a predetermined direction, and the light deflected by each of the light deflecting devices at a constant image plane. A beam scanning device including a scanning device for scanning, wherein each of the light deflecting devices holds a light deflecting member having a reflection surface that reflects light, a support member that supports the light deflecting member, and the support member A holding member having an opening, and a driving mechanism that is disposed in the opening of the holding member and that includes a magnet and a coil for rotationally driving the light deflection member with respect to the holding member, A beam scanning device, wherein a first overhang is formed on a surface of the opening of the holding member that faces the magnetized surface of the magnet. 11. The apparatus according to claim 1, wherein the first overhang has substantially the same area as a magnetized surface of the magnet.
0. The beam scanning device according to 0. 12. A second overhang portion made of a non-magnetic material protrudes from a surface of the opening of the holding member that does not face the magnetized surface of the magnet.
12. The beam scanning device according to 0 or 11.