JP3283217B2 - Scanning position correction device for scanning optical system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device, and more particularly to a correction device for correcting a scanning position in a sub-scanning direction.

[0002]

2. Description of the Related Art An optical scanning device widely used in a laser beam printer or the like is configured to make a laser beam from a laser light source modulated in accordance with drawing information incident on a polygon mirror (optical deflector). Scan in the main scanning direction, and irradiate the scanning laser beam to a photoconductor driven in a sub-scanning direction orthogonal to the main scanning direction via an fθ lens. As the photoconductor, a photoconductor drum, a photoconductor sheet, or the like is used.

In such an optical scanning device, the displacement of the laser beam in the sub-scanning direction on the photosensitive member occurs due to driving unevenness of the photosensitive member, surface inclination of each reflecting surface of the polygon mirror, and the like. There is a problem that the printing quality is deteriorated. Conventionally, the scanning position correction in the sub-scanning direction has been performed by a reflection type optical deflector such as a galvanometer mirror. Becomes larger.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a light transmitting type light deflecting device capable of correcting a scanning position in the sub-scanning direction. Another object of the present invention is to provide a scanning position correction device capable of correcting chromatic aberration.

[0005]

SUMMARY OF THE INVENTION The present invention provides a laser light source modulated in accordance with drawing information; an optical deflector for scanning a laser beam from the laser light source in a main scanning direction; and a driving device in a sub-scanning direction orthogonal to the main scanning direction. And a photoreceptor that receives laser light scanned in the main scanning direction; a wedge-shaped section in the sub-scanning direction in an optical path from the laser light source to the optical deflector; Providing a pair of light transmitting prisms whose apex angles are directed in opposite directions, fixing one of the pair of light transmitting prisms, and supporting the other rotatably about a swing axis orthogonal to the sub-scanning direction, the movable light transmitting prism provided an electromagnetic driving device for driving swing around the swing axis, the thick portion of the movable light-transmitting prism, the rocking
Cross section where the moving axis is a point and the movable light transmitting prism is wedge-shaped
Position, the center of gravity of the movable light transmitting prism and the
It is characterized in that the cutting is performed so that the position of the pivot axis coincides .

Further , the fixed light transmitting prism and the movable light transmitting prism can have the same wedge shape.

The electromagnetic driving device includes, for example, a yoke member;
A movable portion having a movable light-transmitting prism mounted on the yoke member via an elastic means and pivotally around a swing axis; fixed to the movable portion and the yoke member, respectively;
A coil for causing the movable portion to rotate forward and backward around the swing axis by a magnetic action, and a permanent magnet; and the fixed light transmitting prism is a yoke member or a member integral with the yoke member. Can be fixed. This electromagnetic drive device can drive the movable light transmitting prism in accordance with drive unevenness information of the photoreceptor, or based on surface tilt information of each reflection surface of the optical deflector composed of a polygon mirror.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an example of an optical scanning device to which the scanning position correcting device of the present invention is applied will be described with reference to FIGS. This example is a multi-beam scanning apparatus that simultaneously forms eight scanning lines by one scanning by simultaneously scanning eight laser beams.

As shown in FIG. 12, this scanning optical device is configured by disposing a scanning optical system in a flat casing 1 having a rectangular parallelepiped shape. The upper opening of the casing 1 is
At the time of use, it is closed by the upper lid 2.

As shown in FIGS. 13 and 15, the light source unit 100 of the scanning optical system includes eight laser blocks 310a to 310h mounted on a support substrate 300, respectively.
And semiconductor lasers 101 to 108 attached to these laser blocks one by one, eight quartz glass optical fibers 121 to 128, and a coupling lens (shown in FIG. ), And a fiber alignment block 130 which forms eight point light sources arranged in a straight line by holding the ends of the optical fibers on the emission side in a straight line. In addition,
The incident-side ends of the optical fibers 121 to 128 are held by fiber supports 319a to 319h fixed to the laser blocks 310a to 310h.

A divergent light beam emitted from the fiber alignment block 130 of the light source unit 100 is converted into a parallel light beam by a collimating lens 140 held by a cylindrical collimating lens holder 340, and a slit 142
And enters the half mirror 144 which is a light splitting element. The half mirror 144 functions as a light splitting element that splits by transmitting a part of the incident light flux as a monitor light flux and reflecting the remaining light as a main light flux. The transmittance of the half mirror 144 is 5 to 10% as an average of the S-polarized light and the P-polarized light.

The monitor light beam transmitted through the half mirror 144 is incident on an APC (auto power control) signal detecting section 150 which constitutes a light detecting means and a correcting means of the light intensity control device. The APC signal detector 150 includes a condenser lens 151 for converging a transmitted light beam, a polarization beam splitter 153 as a polarization separation element for separating the light beam into two orthogonal polarization components, and detects light energy of each polarization component. APC first light receiving element 155, A
The output signal is used to feedback-control the output of the semiconductor lasers 101 to 108.

On the other hand, the main beam reflected by the half mirror 144 passes through an electromagnetically driven transmission type light deflector 60 having a movable light transmission prism 61 and a fixed light transmission prism 62, and has a positive power only in the sub-scanning direction. Is formed linearly in the vicinity of the mirror surface of the polygon mirror 180 by the cylindrical lens 170 having. The transmissive light deflector 60 moves the movable light transmissive prism 61 along an axis perpendicular to the optical axis in order to correct the positional deviation of the spot on the scan target surface in the sub-scanning direction due to uneven rotation of the photosensitive drum. It rotates around and its rotation position is detected by a position sensor. The cylindrical lens 170 is held by a cylindrical cylindrical lens holder 361, and as shown in FIG. 13, two lenses 171 and 17 having positive and negative powers in the sub-scanning direction, respectively.
3

The polygon mirror 180 is driven by a polygon motor 371 fixed to the casing 1 as shown in FIG. 14, and rotates clockwise as indicated by an arrow in FIG. The polygon mirror 180 is provided with a cover glass 3 as shown in FIG. 12 in order to avoid the generation of wind noise due to rotation and damage to the mirror surface due to collision with dust in the air.
A cup-shaped polygon cover 373 having an optical path hole 373e closed by 75 blocks the air from the outside air.

The light beam transmitted through the cylindrical lens 170 enters the cover through the cover glass 375,
The light is reflected and deflected by the polygon mirror 180, and is again emitted to the outside through the cover glass 375. A sensor block 376 including a polygon sensor (index sensor, not shown) for detecting a mark M provided on the upper surface of the polygon mirror 180 is provided on the upper surface of the polygon cover 373. This index sensor is a sensor that generates one pulse for each rotation of the polygon mirror 180, for example.

On the reflection surface of the polygon mirror 180, for example, an error occurs in the surface shape in the main scanning direction due to processing. In general, the processing error amount of each reflection surface varies. Therefore, the amount of error of each surface is measured and stored in advance, and which reflective surface is used for scanning according to the output of the sensor at the time of use, the unique amount of error for each reflective surface is determined. , The beam position, the beam intensity, and the like can be corrected.

The light beam reflected by the polygon mirror 180 passes through an fθ lens 190 which is an image forming optical system,
As shown in FIGS. 13 and 14, the light is reflected by the folding mirror 200 and reaches the photosensitive drum 210 to form eight beam spots. These beam spots are
Scanning is performed simultaneously with the rotation of the polygon mirror 180,
Eight scanning lines are formed on the photosensitive drum 210 by one scanning. lens 190 includes a first lens 191,
Second lens 193, third lens 195, and fourth lens 1
97.

The photosensitive drum 210 is driven to rotate in the direction of arrow R in synchronization with the scanning of the beam spot, whereby an electrostatic latent image is formed on the photosensitive drum 210. This latent image is transferred to a sheet (not shown) by a known electrophotographic process.

The a-axis in FIG. 12 to FIG.
The axis parallel to the optical axis 90, the b axis, and the c axis are axes orthogonal to each other in a plane perpendicular to the a axis. The b axis coincides with the main scanning direction, and the c axis coincides with the sub scanning direction in the optical path between the polygon mirror 180 and the return mirror 200.

The luminous flux transmitted through the fθ lens 190 is detected by the synchronization signal detecting optical system 220 before entering the drawing range for each scan, that is, for each scan by one reflection surface of the polygon mirror. The synchronization signal detecting optical system 220 is disposed in an optical path between the fourth lens 197 of the fθ lens 190 and the return mirror 200, and reflects a light beam before the drawing range, and the first mirror 221. The light emitting device 221 includes second and third mirrors 223 and 225 that sequentially reflect the light beam reflected by the light-receiving device 221 and a light receiving element 230 that receives the light beam guided by these mirrors. The light receiving element 230 is arranged at a position optically equivalent to the photosensitive drum 210. The eight beams
With the scanning, the light enters the light receiving elements 230 one by one in order,
Eight pulses are output from the light receiving element 230 for each scan. When a pulse is detected, one line of image data is transferred to a laser driving unit that drives a semiconductor laser corresponding to the Hals, and writing is started after a lapse of a predetermined time from the detection of the pulse.

Further, the casing 1 is provided with a drawing opening 11 for transmitting the light beam reflected by the folding mirror 200, and the drawing opening 11 is provided with a cover glass 20.
1 is attached.

FIGS. 1 to 10 show a transmission type light deflector 60 having a position sensor, which is used in the above optical scanning device. First, a schematic configuration will be described with reference to FIGS. 1 to 4. A yoke member (base member) 10 made of a magnetic material has a cylindrical portion 10 </ b> C, and a cylindrical movable member located in the cylindrical portion 10 </ b> C. The movable light transmitting prism 61 is fixed to the section 12.

The movable part 12 includes a cylindrical part 10C and the movable part 12
Are elastically rotatably supported around a swing axis (elastic main axis, Z axis). This elastic main axis Z is orthogonal to the optical axis of the optical path from the half mirror 144 to the polygon mirror 180.

The movable light transmitting prism 61 supported by the cylindrical movable portion 12 has a wedge-shaped cross section in the sub-scanning direction, and has a thicker uniform cross section as it goes upward. This prism 61 has a front non-circular shape obtained by cutting off a part of the upper part of the front circular prism along a cutting line 61 ′. The cutting line 61 ′ is determined so that the position of the center of gravity X after cutting coincides with the elastic main axis Z. More specifically, the front non-circular prism 61
When viewed from the front, the elastic main axis Z runs in the left-right direction, and the new center of gravity X is located on the elastic main axis Z. At the cross-sectional position where the elastic principal axis Z is a point and the prism 61 is wedge-shaped, the center of gravity X coincides with the elastic principal axis Z.
The cutting line 61 ′ of the prism 61 is parallel to the main elastic axis Z.

On the other hand, a fixed light transmitting prism 62 is fixed to the cover member 14 integral with the yoke member 10.
As shown in FIG. 3 and FIG.
Has the same wedge shape as the movable light transmitting prism 61,
It is in a positional relationship in which the apex angle is turned upside down with the apex angle in the opposite direction. That is, the fixed light transmitting prism 62 is thicker downward in the sub-scanning cross section. As described above, when the laser beam is transmitted through the pair of prisms 61 and 62 of the same material (refractive index) having the same wedge angle with the apex angle directed in the opposite direction, the chromatic aberration generated by the first prism is canceled by the next prism. Therefore, chromatic aberration does not occur in the transmission type light deflector 60.

A pair of mutually independent coils 12C and 12D are fixed to the outer peripheral surface of the movable portion 12. The coils 12C and 12D are orthogonal to the central axes of the coils 12C and 12D, are symmetrically arranged before and after a plane including the Z axis, and are made of the same coil.

On the other hand, on the inner surface of the cylindrical portion 10C of the yoke member 10, the front and rear surfaces of a plane perpendicular to the center axes of the coils 12C and 12D and including the Z-axis correspond to (oppose) the coils 12C and 12D. , A pair of semi-circular half permanent magnet segments 18 and 20 are fixed respectively. The pair of half permanent magnet segments 18 are fixed to the yoke member 10 via the permanent magnet holder member 16 and have opposite polarities, and the pair of half permanent magnet segments 20 also have opposite polarities. It is. That is, one of the permanent magnet segments 18 and 20 has an N pole on the inner peripheral side and an S pole on the outer peripheral side, and the other has an N pole on the inner peripheral side and an S pole on the outer peripheral side. The polarities of the half permanent magnet segments are reversed so that the polarities of the half permanent magnet segments 18 and 20 that are orthogonal to the central axes of the coils 12C and 12D and located before and after a plane including the Z axis are opposite to each other. Have been.

According to the above configuration, the coils 12C and 12D
Then, current flows in opposite directions to each other,
2 can be driven forward and reverse around the Z axis. Movable part 1
When 2 rotates about the elastic main axis Z, the light beam L incident on the movable light transmitting prism 61 and refracted is deflected according to the rotation angle. Since the center of gravity X of the movable light transmitting prism 61 overlaps the elastic main axis Z, the movable portion 1
In the rotation of 2, there is not only no energy loss, but also no weight imbalance with respect to the rotation center that causes vibration. Therefore, high-speed and high-precision driving becomes possible.

Further, when currents in opposite directions flow through the pair of coils 12C and 12D, the mutual inductance of the coils decreases. The polarities of the half permanent magnet segments 18 and 20 are opposite to each other so that when currents in opposite directions are applied to the coils 12C and 12D, a rotating thrust is generated in the movable portion 12 in the same direction. The magnetic circuit constituted by the split permanent magnet segments 18, 20 and the yoke member 10 is less likely to be saturated, and the yoke member 10
The thickness of the (cylindrical portion 10C) can be reduced.

The position sensor is connected to the movable part 12 described above.
This is for detecting a change in the angle of the movable light transmitting prism 61 due to the rotation of. In the movable light transmitting prism 61,
Outside (lower side) of the use area (laser beam transmission area) S
1 is provided with a reflection coat R on the surface on the thin side ( FIG. 1 ) .
Area of hatching). On the other hand, the case member 50 integral with the yoke member 10 is provided with a light irradiating means 51 for arranging a laser beam at an angle to the reflection coat R by being positioned in a plane orthogonal to the reflection coat surface and parallel to the Z axis. And an incident position detecting unit 55 that receives a light beam emitted from the light irradiation unit 51 and reflected by the reflection coat R is fixed. The light irradiation unit 51 includes an LD 52 and a collimator lens 53 that converts a laser beam emitted from the LD 52 into a parallel beam, and an incident position detection unit 55 includes a condenser lens that condenses the laser beam reflected by the reflection coat R. 56, and a PSD (POSISTION SENSING DEVICE, incident position detector) PSD 57 on which the converged light beam enters.

Light irradiating means 51 and incident position detecting means 55
Are positioned so that the laser beam emitted from the LD 52 is reflected by the reflection coat R of the movable light transmitting prism 61 and enters the PSD 57, and the coils 12C and
The incident position on the PSD 57 in the non-energized state to the 2D is the reference position of the movable light transmitting prism 61. And
Energizing the coils 12C and 12D in the normal and reverse directions,
That is, when the movable light transmitting prism 61 is rotated around the Z axis, the incident position of the laser light on the PSD 57 changes.
Since the change in the incident position occurs in a direction perpendicular to the paper surface of FIG. 4, the change in the incident position appears as a change in the output of the PSD 57. Therefore, by feeding back the output of the PSD 57 to, for example, the rotation control system of the photosensitive drum 210, it is possible to prevent the image quality from deteriorating due to the uneven rotation of the photosensitive drum 210.

FIG. 11 shows an example of the control system of the optical scanning device having the transmission type light deflector 60 described with reference to FIGS. The components described with reference to FIGS. 12 to 15 are housed in the casing 1, pass through the transmission-type light deflector 60, are reflected by the polygon mirror 180, and have fθ
The laser beam transmitted through the lens 190 and reflected by the return mirror 200 is incident on the photosensitive drum 210. As described above, the polygon motor 371 of the polygon mirror 180 is provided with a sensor block 376 having an index sensor that generates one pulse (Hsync signal) for each rotation of the polygon mirror 180. Further, the surface tilt amount of each surface of the polygon mirror 180 is measured in advance and stored in the memory 63 as a data table for each surface, and from the stored surface tilt amount and the Hsync signal, the surface used for scanning is determined. Is output (polygon mirror correction amount).

On the other hand, the rotational position of the photosensitive drum 210 is
The rotation position signal of the photosensitive drum 210 detected by the encoder 64 is input to the prism position control amount calculation device 66 together with the writing position signal (drawing signal) from the printer controller 65. The prism position control amount calculation device 66 calculates a control amount (rotation amount) of the movable light transmitting prism 61 (drum position correction amount).

The prism position control device 67 controls the current supplied to the coils 12C and 12D in accordance with the polygon mirror correction amount and the drum position correction amount to supply a drive signal to the movable light transmitting prism 61. Out of the light irradiating means 51 and the reflection coat R of the movable light transmitting prism 61
After that, the position detection signal of the prism is incident on the incident position detecting means 55. The angle of the movable light transmitting prism 61 is controlled by this closed loop so that even if the photosensitive drum 210 has slight rotation unevenness, the scanning beam is swung in the sub-scanning direction in accordance with the rotation unevenness. In addition, the photosensitive drum 2 by the light transmitting prism 61
The position correction amount in the sub-scanning direction on the line 10 is about 1 μm, and the deflection angle of the scanning beam is about 0.1 to several seconds. According to the above control, even when slight rotation unevenness (positional deviation) of the photosensitive drum 210 affects print quality as in the case of multicolor printing, the influence of the rotation unevenness can be minimized. it can. The light irradiation means 51 includes a collimating lens 5
Since the laser light flux converted into a parallel light flux in step 3 is applied to the prism movable light transmitting prism 61, even if the prism movable light transmitting prism 61 has a movement other than rotation such as a parallel movement, the angular position can be accurately detected. High resolution and responsiveness can be obtained in combination with the use of the PSD 57 for the incident position detecting means 55.

FIGS. 5 to 10 show details of the transmission type light deflector 60 for driving the movable light transmission prism 61. FIG. The base member 10 includes a base 10A and the base 1
0A and a frame portion 10B integrally upright. The base member 10 functions as a mounting part when the present optical deflecting device is incorporated as a component of an optical system. The frame portion 10B has an annular shape defining a circular opening 10C. The short cylindrical movable portion 12 is disposed in a circular opening (cylindrical portion) 10C of the frame portion 10B, and is provided via the elastic means 22 to the frame portion 10B of the base member 10.
Supported by

A substantially rectangular cover member 14 is appropriately mounted on the front side of the base member 10, and a light transmitting prism 62 is fixed to a central circular opening of the cover member 14. On the other hand, on the rear side of the base member 10, a permanent magnet holder member 16 is appropriately mounted. The permanent magnet holder member 16 has a holder portion 16A having a short cylindrical shape and a diameter integrally formed from the holder portion 16A. And a pair of mounting plates 16B projecting in the direction. A pair of half permanent magnet segments 18 and 20 are provided in the holder portion 16A, and each of the permanent magnet segments 18 and 20 is provided at a position perpendicular to the center axis of the coils 12C and 12D and before and after a plane including the Z axis. As described with reference to FIG. 3, the polarization process for the half permanent magnet segments 18 and 20 is performed such that one of the permanent magnet segments 18 and 20 has an N pole on the inner peripheral side and an S pole on the outer peripheral side, and the other has an N pole on the inner peripheral side. And the outer peripheral side is the S pole. The polarity is also reversed between the front and rear half permanent magnet segments 18 and 20.

The pair of mounting plates 16B are used to mount the permanent magnet holder member 16 to the frame portion 10B of the base member 10, and the holder member 16A is housed in the circular opening 10C of the frame portion 10 at the time of mounting. And is arranged so as to cover the periphery of the two pairs of half permanent magnet segments 18 and 20. Note that the cover member 14 and the holder member 16 are preferably formed of the same material as the base member 10.

Referring to FIG. 6, the movable portion 12 is shown in an enlarged exploded perspective view. The movable portion 12 includes an optical deflection element holder member 12A having a short cylindrical shape,
The movable light transmitting prism 61 is mounted in the optical deflection element holder member 12A.

As shown in FIG. 6, the optical deflection element holder member 12A has a polygonal central flange portion 12A.
Include _1, the collar portion 12A ₂ and 12A ₃ projecting from both sides of the central flange portion 12A _1. Movable part 12
Are the collar portions 12A ₂ and 1 of the optical holder member 12A.
And it comprises a coil 12C and the coil 12D mounted to each of 2A _3. As described above, the coil 12C and the coil 12D are independent of each other and can supply current separately, and the driving mechanism for driving the movable portion 12 in cooperation with the half permanent magnet segments 18 and 20 Function as In FIG. 6, the coils 12C and 12D are shown as annular rings, but each of the coils 12C and 12D is obtained by winding a conductive wire into an annular ring.
The illustration of the feed lines to C and 12D is omitted.

Further, the movable unit 12 further comprises a leaf spring coupling 12E mounted on either side of the central flange portion 12A ₁ in the diameter direction of the optical deflection element holder member 12A. FIG. 6 shows a coupling 1 for a leaf spring on one side.
2E but it is shown coupling a similar leaf spring is also provided on the opposite side of the diametrical direction of the central flange portion 12A _1. Coupling 12E for the leaf spring and the stationary coupling part 12E ₁ adapted to be fixed to the central flange portion 12A _1, a movable coupling unit 12E ₂ became detachable from the fixed coupling part 12E ₁ Consists of

A composite leaf spring body (elastic means) 22 is connected to each leaf spring coupling 12E. In this embodiment, the composite leaf spring body 22 is composed of four leaf spring elements 22A. As shown in detail in FIG. 7, in the present embodiment, H
A slit 24 is formed in the L-shaped leaf spring material in such a manner as to divide it in half, thereby forming a pair of leaf spring elements 22A in the H-shaped leaf spring material. By combining such two H-shaped leaf spring materials along their slits 24, a composite leaf spring body (elastic means) 22 as shown in FIG. 8 is obtained.
Around the longitudinal central axis of the slit 24.
The leaf spring elements 22A are arranged at regular intervals at an angle of 90 degrees.

As shown in FIG. 5, another leaf spring coupling 26 is provided on the opposite side of the leaf spring coupling 12E, and this leaf spring coupling 26 is attached to the frame portion 10B of the base member 10. and fixing the coupling portion 26 ₁ which is fixed, consisting of freely movable coupling portion 26 ₂ which detachable from the fixed coupling part 26 _1. Cup plate spring ring 26, except that the fixing coupling portion 26 ₁ is integrated with the mounting block piece 28 having a through-hole is the same as the configuration of the coupling 12E for leaf springs described above.

As shown in more detail in FIG. 8, the fixed coupling part 26 ₁ is formed as a tubular short shaft member 26A integrally projecting from the mounting block piece 28, and from the free end face of the tubular short shaft member 26A. Four claw elements 26B protrude. The four claw elements 26B are the tubular short shaft members 26.
A is arranged at equal intervals at an angle of 90 degrees along the circumferential direction of A,
The cross section of each claw element 26A has a segment shape as shown. A pair of flat surfaces 26C diametrically opposed to each other are formed on the side of the tubular short shaft member 26A. FIG. 8 illustrates only one of the pair of flat surfaces 26C.

On the other hand, is also movable coupling portion 26 ₂ is formed as a tubular minor axis member 26D, the diameter of which is larger than the tubular minor axis member 26A, the tubular short axis member 26A is fitted loosely in a tubular minor axis member 26D It is possible to match. As in the case of the tubular short shaft member 26A, the tubular short shaft member 26D
Four claw elements 26E protrude from one free end face of
These four claw elements 26E are arranged at equal intervals at an angle of 90 degrees along the circumferential direction of the tubular short axis member 26D, and the cross section of each claw element 26E has a segment shape as shown. As is clear from FIG. 9, the tubular short shaft member 26D
Are formed with two pairs of flat surfaces 26F and 26G diametrically opposed to each other. In FIG. 8, only one of each of the two pairs of flat surfaces 26F and 26G is illustrated.

As shown in FIG. 9, screw holes 26H and 26I are formed in two pairs of flat surfaces 26F and 26G formed in the tubular short shaft member 26D, respectively.
6H and 26I are eccentrically shifted in opposite directions with respect to the longitudinal center axis of the tubular short shaft member 26D. That is,
In the example shown in FIGS. 8 and 9, the screw hole 26H formed in the flat surface 26F which can be seen in FIG.
When viewed from the four claw elements 26E side of 6D, the screws are shifted counterclockwise and formed on a flat surface 26F (FIG. 9) diametrically opposite to the flat surface 26F. The hole 26H is also displaced counterclockwise. As is clear from FIG. 9, the same can be said for the pair of screw holes 26I formed in the other pair of flat surfaces 26G as in the above-described pair of screw holes 26H.

Therefore, the movable coupling part 26 ₂ is attached to the fixed coupling part 26 ₁ , and both the claw elements 26 B
9 and 26E are engaged with each other in the manner shown in FIG. 9, and then a pair of setscrew elements 30 (FIG. 8) are screwed into, for example, a pair of screw holes 26H.
Is the flat surface 26C of the fixed coupling part 26 _{1 first.}
Contact, by further screwing the set screw element 30, the movable coupling part 26 ₂ and the fixed coupling part 26 ₁ are both subjected to the opposite direction of the turning force to one another, the engagement thereby pawl elements 26B and 26E each other in The surfaces are urged against each other. Claw elements 26B and 2
6E each leaf spring element 2 of the composite leaf spring body 22
By performing the screwing operation of the pair of setscrew elements 30 as described above while sandwiching the corresponding end of 2A,
The composite leaf spring body 22 is fixedly connected to a leaf spring coupling 26.

As described above, the configuration of the leaf spring coupling 26 itself is the same as the leaf spring coupling 12E, and the composite leaf spring body 22 is similar to the leaf spring coupling 12E in the same manner. Fixedly connected.

FIG. 5 shows the movable part 12 in an assembled state. At this time, a pair of leaf spring couplings 12E is provided.
Is fixedly connected to one end of the composite leaf spring body 22, and a leaf spring coupling 26 is fixedly connected to the other end of the composite leaf spring body 22. The fixed coupling part 26 ₂ of the mounting block piece 28 of each plate spring coupling 26 is a bolt element 32 is inserted into the through hole,
Each bolt element 32 is further connected to the frame 10 of the base member 10.
B is screwed into a screw hole 10D formed in the diameter direction.
As is clear from FIG. 5, each screw hole 10D is disposed in a recess formed in the frame portion 10B, and each bolt element 3D
When the mounting block piece 28 is screwed into the mounting block piece 2, the mounting block piece 28 is accommodated in the recess.

Thus, the movable portion 12 is supported by the frame portion 10B of the base member 10 via the pair of composite leaf spring bodies 22, and at this time, the movable portion 12 is supported by the longitudinal portions of the leaf spring couplings 12E and 26. It is easiest to move around the directional center axis, that is, the longitudinal center axis of the composite leaf spring 22. More specifically, as shown in FIG.
A three-dimensional coordinate system having the origin at the center of 2 is set. At this time, one pair of leaf spring elements 22A is located in the XZ plane, and the other pair of leaf spring elements 22A is located in the YZ plane. If so, the compliance around the X axis (α) and the compliance around the Y axis (β) are substantially the same as each other, and are much larger than the compliance around the Z axis (γ). Become. In short, in the configuration of the composite leaf spring body 22 shown in the figure, the low compliance is obtained only around the Z axis (γ).

On the other hand, the coil 12C and the coil 12D of the movable part 12 are two pairs of the half permanent magnet segments 18 and 20.
When the current is supplied within the magnetic field obtained by the above, the movable portion 12 receives a rotating force around the Z-axis according to Fleming's left-hand rule, and the direction of rotation depends on the direction of current supply to the coils 12C and 12D. In short, the Z axis is the movable part 1
The second rotation axis is the elastic main axis.

According to the arrangement of the composite leaf spring body 22 described above, low compliance can be imparted only around the elastic main axis (Z-axis) of the movable part 12, so that the external Even if an external force such as vibration is applied to the optical deflecting device, the movable portion 12 can move the elastic main axis (Z
It can rotate stably only around the axis).

In particular, when the position X of the center of gravity of the movable light transmitting prism 61 (that is, the position of the center of gravity of the movable portion 12) is located on the elastic main axis (Z axis), the structure-coupled vibration at the movable portion 12 is achieved. Can be effectively eliminated.

[0053]

According to the present invention, in a scanning optical system,
The scanning position in the sub-scanning direction can be corrected by the light transmission type light deflecting device, and the occurrence of chromatic aberration can be suppressed, so that the degree of freedom of the configuration of the scanning optical system can be increased.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a scanning position correcting device for a scanning optical system according to the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 1;

FIG. 5 is an exploded perspective view showing a specific example of an electromagnetic driving device of the scanning position correction device shown in FIG.

FIG. 6 is an exploded perspective view of a movable portion of the device shown in FIG.

FIG. 7 is an exploded perspective view of a composite leaf spring body (elastic member) supporting the movable portion shown in FIG.

FIG. 8 is an exploded perspective view of a leaf spring coupling for connecting the composite leaf spring shown in FIG. 5;

FIG. 9 is an end view of the leaf spring coupling shown in FIG. 8;

FIG. 10 is an assembled perspective view of the composite leaf spring body shown in FIG. 7, and is an explanatory diagram for explaining its characteristics.

FIG. 11 is a block diagram showing an example of a control system of the scanning position correcting device of the scanning optical system of the present invention.

FIG. 12 is a perspective view showing an example of a multi-beam optical scanning device using a scanning position correcting device for a scanning optical system according to the present invention.

FIG. 13 is a plan view of FIG.

14 is a sectional view taken along the line XIV-XIV in FIG.

FIG. 15 is a plan view showing only the optical system of the apparatus shown in FIG. 12;

FIG. 16 is an optical path diagram showing only a fixed light transmitting prism and a movable light transmitting prism.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Base member (yoke member) 10A Base part 10B Frame part 10C Circular opening (tubular part) 12 Movable part 12C 12D Coil 18 20 Permanent magnet 22 Elastic means Z Oscillating axis (elastic main axis) 14 Case member (yoke) 60 Transmission type light deflector 61 Movable light transmission prism 62 Fixed light transmission prism R Reflection coat 64 Encoder 65 Printer controller 66 Prism position control amount calculation device 67 Prism position control device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-273829 (JP, A) JP-A-4-287011 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B 26/10

Claims (5)

(57) [Claims] A laser light source that is modulated in accordance with drawing information; an optical deflector that scans laser light from the laser light source in a main scanning direction; and a light deflector that is driven in a sub-scanning direction orthogonal to the main scanning direction. A scanning optical system comprising: a photoreceptor that receives a laser beam scanned in a scanning direction; wherein in the optical path from the laser light source to the optical deflector, the cross-sectional shape in the sub-scanning direction is wedge-shaped and the apex angle is opposite. A pair of light-transmitting prisms directed in the direction, one of the pair of light-transmitting prisms is fixed, and the other is supported rotatably about a swing axis orthogonal to the sub-scanning direction. the prism is provided an electromagnetic driving device for driving swing around the swing axis, the thick portion of the movable light-transmitting prism, the swing axis
Point and the movable light transmitting prism has a wedge-shaped cross-sectional position.
And the center of gravity of the movable light transmitting prism and the swing axis.
A scanning position correcting device for a scanning optical system, wherein the scanning position is corrected so as to match the position. 2. The scanning position correcting device for a scanning optical system according to claim 1, wherein said electromagnetic driving device includes a yoke member;
A movable portion having the movable light transmitting prism mounted on the yoke member via an elastic means and pivotally about an oscillation axis; fixed to the movable portion and the yoke member, respectively; The movable portion includes a coil and a permanent magnet that generate forward and reverse rotational movement about the swing axis; and the fixed light transmitting prism is fixed to the yoke member or a member integrated with the yoke member. Scanning position correcting device for a scanning optical system. 3. The scanning position correcting device for a scanning optical system according to claim 1, wherein the electromagnetic driving device oscillates the movable light transmitting prism in accordance with driving unevenness information of the photosensitive member. Scanning position correction device for a scanning optical system. 4. The method according to claim 1, wherein
In the scanning position correcting device of the scanning optical system , the optical deflector comprises a polygon mirror, and the electromagnetic driving device swings and drives the movable light transmitting prism based on information on the inclination of each reflecting surface of the polygon mirror. Scan position correction system. 5. The method according to claim 1, wherein
In the scanning position correcting apparatus for a scanning optical system , the fixed light transmitting prism and the movable light transmitting prism have the same wedge shape.