JP2010061049A - Optical scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem wherein a conventional optical deflector is fixed on a housing by taking a position remote from the fixing shaft of the optical deflector as a reference face, and then a large tilt of the axis occurs. <P>SOLUTION: The optical deflector 6 is fixed on the housing of the optical scanner and the optical deflector 6 includes at least: a fixing shaft; and a rotating body 17 which has a polygon mirror 14 and is inserted into the fixing shaft with a gap, wherein one end of the fixing shaft is inserted into a hole formed on the housing, the optical deflector is fixed on the housing so that the part composing the optical deflector except the one end of the fixing shaft, is not made contact to the housing, and then the tilt of the shaft of the optical deflector is prevented. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical scanning device used for a laser printer, a digital copying machine, an exposure device for medical equipment, and the like.

  An optical scanning device used in an image forming apparatus such as a laser printer or a digital copying machine is a light source that emits laser light, an optical deflector that deflects and reflects the laser light emitted from the light source, and is deflected and reflected by the optical deflector. A mirror for guiding the laser beam to the photosensitive drum, various lenses, and the like (for example, see Patent Documents 1 to 4).

Here, as an optical deflector, what is shown by FIG. 5 is known (for example, refer patent document 5).
The optical deflector includes a columnar fixed shaft 101 fixedly disposed on the housing 100 and a rotating body 110 that is rotatably supported by the fixed shaft 101.
The rotating body 110 includes a sleeve 111 disposed with a slight gap between the rotating shaft 110, a ring-shaped magnet 112 fixedly disposed on the upper inner side of the sleeve 111, and an outer central portion of the sleeve 111. A polygon mirror 113 fixedly disposed on the lower surface of the sleeve 111 and a ring-shaped drive magnet 115 fixedly disposed on the outside of the lower portion of the sleeve 111 via a flange 114.
Reference numeral 116 denotes a groove in which a balance weight (not shown) for correcting the eccentricity of the weight of the rotating body 110 is attached.

  A ring-shaped magnet 102 is fixedly disposed on the outer side of the upper portion of the fixed shaft 101 so as to face a ring-shaped magnet 112 provided on the rotating body 110. The rotating body 110 is supported by the ring-shaped magnets 102 and 112. A thrust magnetic bearing S for bearing in the thrust direction is configured.

  Furthermore, an iron core coil 103 is fixedly disposed on a metal base member 100 made of aluminum or the like so as to face a ring-shaped drive magnet 115 provided on the rotating body 110. A motor M that rotates the rotating body 110 is constituted by the coil 103.

  Of the sleeve 111 of the rotating body 110, the inner peripheral surface 111a facing the fixed shaft 101 is finished with a bearing surface, while the outer peripheral surface 101a of the fixed shaft 101 facing the inner peripheral surface 111a of the sleeve 111. Are formed with herringbone-shaped grooves 104 as shown by broken lines in the figure, and the rotating body 110 is radially formed by the grooves 104 provided on the inner peripheral surface 111a of the sleeve 111 and the outer peripheral surface 101a of the fixed shaft 101. A radial dynamic pressure bearing R that is supported in the direction is configured.

In this optical deflector, when the rotating body 110 is rotated by the motor M, the rotating body 110 is supported in a non-contact manner with a fixed distance (gap) with respect to the fixed shaft 101 by the radial dynamic pressure bearing R, and the thrust magnetism. The bearing S supports the fixed shaft 101 at a constant height. Accordingly, there is an advantage that the height of the optical deflector can be made lower than that of a type using a dynamic pressure bearing as a bearing in the thrust direction.
Moreover, since the position of the center of gravity of the rotating body 110 can be set to the position of the approximate center in the axial direction of the rotating body 110, the rotating body 110 can be stably rotated.

  This optical deflector needs to scan four beams corresponding to each color at the same position on four different photosensitive drums in accordance with recent high-quality color formation of image formation. High-precision fixing is required.

JP 2007-183327 A JP-A-10-268222 JP 2005-156926 A JP 2007-183492 A JP-A-5-071532

  However, since the above-described optical deflector has the base member 100, the number of parts of the optical deflector is large, and the structure of the base member 100 is complicated, so that the cost of the optical scanning device increases. . That is, when the optical deflector is fixed to the resin housing of the optical scanning device, a male screw is inserted into a hole or the like (not shown) formed in the end of the base member 100, and the female screw is formed in the housing. It was common to screw in.

In order to solve such a problem and simplify the structure of the optical deflector, an inexpensive optical scanning apparatus in which the base member 100 described above is eliminated and the fixed axis of the optical deflector is fixed to the substrate has been widely used. (See Patent Documents 1 to 4).
However, in such a conventional optical scanning device, the optical deflector is fixed to the housing with a position that is far away from the fixed axis of the optical deflector as a reference plane. It was.
Here, the axis collapse means that there is an angular difference between the axial direction of the fixed axis of the optical deflector and the vertical direction when the housing is placed on a horizontal surface. This axis tilt is a main cause of image plane bending and scanning line bending of the optical scanning device.

  The present invention has been made to solve such a problem, and by fixing only the fixed shaft or only the holder that rotatably supports the rotating shaft in contact with the housing, the shaft of the optical deflector can be inexpensively fixed. It is an object of the present invention to provide an optical scanning device capable of eliminating or reducing the tilt and an image forming apparatus using the same.

(First invention)
The first invention relates to an optical scanning device in which an optical deflector including at least a fixed shaft and a rotating body inserted into the fixed shaft with a gap and having a polygon mirror is fixed to a housing. is there.

  Then, one end of the fixed shaft is inserted into the hole formed in the housing, and the optical deflector is fixed to the housing so that other parts constituting the optical deflector other than one end of the fixed shaft do not contact the housing. is there.

  In order for the polygon mirror fixed to the rotating body to deflect and reflect the laser light with high accuracy, it is necessary to assemble the optical scanning device with reference to a fixed axis that serves as a reference for rotation of the rotating body. For this reason, according to the first aspect of the invention, only one end of the fixed shaft is fixed in contact with the housing among the various parts constituting the optical deflector. That is, only one end of the fixed shaft of the optical deflector is inserted and fixed in the hole formed in the housing of the optical scanning device, and other portions other than the fixed shaft are not in contact with the housing.

  With this configuration, it is possible to attach (fix) the optical deflector to the housing with high accuracy on the basis of the outer peripheral surface of the fixed shaft that is processed with high accuracy. Furthermore, when the optical deflector is fixed to the housing, no other external force is applied to the optical deflector because other parts of the optical deflector other than the fixed shaft are not in contact with the housing. For this reason, it is possible to eliminate or reduce the axial collapse of the optical deflector.

(Second invention)
According to a second aspect of the present invention, an optical deflector including at least a rotating shaft, a holder that rotatably supports the rotating shaft, and a rotating body that is fixed to the rotating shaft and includes a polygon mirror is fixed to the housing. The present invention relates to an optical scanning device.

  Then, a holder is inserted into a hole formed in the housing, and the optical deflector is fixed to the housing so that other parts other than the holder do not contact the housing.

  In order for the polygon mirror fixed to the rotating body to deflect and reflect the laser light with high accuracy, the optical scanning device is assembled based on the holder that rotatably supports the rotating shaft that serves as a reference for rotating the rotating body. There is a need. For this reason, according to the second aspect of the present invention, among the various parts constituting the optical deflector, only the holder is fixed in contact with the housing. That is, only the holder of the optical deflector is inserted and fixed in the hole formed in the housing of the optical scanning device, and other parts other than the holder are not in contact with the housing.

  With this configuration, it is possible to attach (fix) the optical deflector to the housing with high accuracy based on the outer peripheral surface of the holder. Furthermore, when the optical deflector is fixed to the housing, no other external force is applied to the optical deflector because other parts of the optical deflector other than the fixed shaft are not in contact with the housing. For this reason, it is possible to eliminate or reduce the axial collapse of the optical deflector.

(Third invention)
According to a third aspect of the present invention, there is provided the optical scanning device according to the first or second aspect, wherein the substrate on which the driving element for rotating the rotating body is mounted is fixed to a fixed shaft or a holder, and the peripheral portion of the substrate is defined as a free end. It is a thing.

  With this configuration, the same effects as those of the first invention or the second invention described above can be obtained. And, compared with a conventional optical scanning device in which the optical deflector is fixed using the peripheral portion of the substrate, unnecessary vibration transmitted from the peripheral portion of the substrate to the rotating body via the fixed shaft or the rotating shaft is eliminated. Can do.

(Fourth invention)
According to a fourth aspect of the present invention, there is provided the optical scanning device according to the third aspect, wherein an elastic member is provided between the peripheral portion of the substrate and the housing.
Even in such a configuration, since the optical deflector is substantially fixed to the housing only by the fixed shaft or the holder, not only the effects similar to those of the first to third inventions described above can be obtained, but also the substrate. Occurrence of vibrations at the peripheral edge can be suppressed.

  According to the present invention, it is possible to provide an optical scanning device in which the axis of the optical deflector is not tilted or reduced.

  Hereinafter, the present invention will be described in detail using examples.

A first embodiment according to the present invention will be described with reference to FIGS.
FIG. 1 is a plan view of an optical scanning device according to the present invention, and FIG. 2 is a cross-sectional view (a cross-sectional view taken along the line AA in FIG. 1) showing an optical deflector fixed to a housing. In order to simplify the explanation, only the fixed shaft is not shown in a sectional view in FIG.

[Optical scanning device]
First, the basic configuration of the optical scanning device according to the present invention will be described.
As shown in FIG. 1, an optical scanning device 1 includes a light source 2 such as a laser diode that emits laser light 3, a collimator lens 4 that collimates the laser light 3 emitted from the light source 2, and a collimator lens 4. A cylindrical lens 5 that narrows the laser beam 3 that has passed through in the sub-scanning direction, an optical deflector 6 that includes a polygon mirror 14 that deflects and reflects the laser beam 3 that has passed through the cylindrical lens 5 in the main scanning direction, and the polygon mirror 14 deflects the laser beam 3. It has an Fθ lens 8 and a reflection mirror 9 that guide the reflected laser light 3 to the photoreceptor 7.

  Here, the main scanning direction refers to the moving direction of the laser beam 3 when the optical scanning device 1 irradiates the surface of the photoconductor 7 with the laser beam 3. The sub-scanning direction is the moving direction of the surface of the photoconductor 7. The main scanning direction and the sub-scanning direction are orthogonal to each other.

The optical scanning device 1 also includes a reflection mirror 10 and a detection sensor 11 for detecting the timing at which the laser beam 3 scans the surface of the photoconductor 7.
The light source 2, the collimator lens 4, the cylindrical lens 5, the optical deflector 6, the Fθ lens 8, the reflection mirrors 9 and 10, and the detection sensor 11 are fixed to the housing 12.

[Optical deflector]
Next, the configuration of the optical deflector 6 will be described in detail.
As shown in FIG. 2, the optical deflector 6 includes a metal substrate 13, a multistage cylindrical and aluminum fixed shaft 16 fixed to the substrate 13 by a plurality of screws 15, and the fixed shaft 16. It is comprised from the rotary body 17 supported rotatably.

  The rotating body 17 includes an aluminum flange 18, a drive magnet 20 fixed to the inner peripheral surface of the skirt portion 19 of the flange 18 with an adhesive, a polygon mirror 14 mounted on the upper surface of the flange 18, a polygon A spring 21 placed on the upper surface of the mirror 14 and a pressing member 22 that is press-fitted and fixed to the upper portion of the flange 18 while pressing the spring 21 downward.

  Since the spring 21 is pressed downward by the pressing member 22, the polygon mirror 14 is fixed by being pressed against the flange 18 by the elastic force generated by the spring 21. A ring-shaped motor core 23 having a plurality of coils is fixed to the substrate 13 with screws 15, an adhesive, and the like, and the terminals of the coils are soldered to wirings provided on the substrate 13.

  The coil of the motor core 23 fixed to the substrate 13 is excited by an electrical signal sent from the driver IC 24 or the like mounted on the substrate 13, and the drive magnet 20 that is circumferentially opposed to the coil moves to move the rotating body. 17 rotates at high speed.

[Fixed structure of optical deflector]
In this optical deflector 6, a lower portion 25, which is one end of a fixed shaft 16, is inserted and fixed in a hole 26 formed in the housing 12. This fixing may be performed by press-fitting the fixed shaft 16 into the hole 26, or a screw hole is formed in an annular protrusion 27 provided on the back surface of the housing 12, and a male screw is screwed into the screw hole to thereby form the hole 26. The lower portion 25 of the fixed shaft 16 inserted into the shaft may be firmly fixed.

  With such a configuration, the optical deflector 6 can be fixed to the housing 12 with high accuracy using the outer peripheral surface of the fixed shaft 16 processed with high accuracy as a reference. Further, since the optical deflector 6 has the peripheral edge 50 of the substrate 13 as a free end and the other part of the optical deflector 6 other than the fixed shaft 16 is not in contact with the housing 12, an extra portion from the housing 12 is provided. No external force is applied. For this reason, the axial collapse of the optical deflector 6 can be eliminated or reduced.

A second embodiment according to the present invention will be described below with reference to FIG.
FIG. 3 is a sectional view showing a state in which the optical deflector is fixed to the housing. In order to simplify the explanation, in FIG. 3, the sections other than the rotating shaft are shown in cross section.
Only the differences from the first embodiment will be described in detail, and the same parts as those of the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted.

  The main difference between the second embodiment and the first embodiment is that the optical deflector 6 does not have a fixed shaft, but has a holder 48 and a rotation shaft 47.

[Optical deflector]
The optical deflector 6 includes a ceramic holder 48 and a rotating body 17 in which a ceramic rotating shaft 47 (outer diameter φ11 mm) is rotatably inserted into the holder 48 with a slight gap (4 μm). Yes.

  The rotating body 17 is made of an aluminum having a rotating shaft 47, an aluminum flange 46 fixed to the rotating shaft 47, and an aluminum flange having a large number of mirror surfaces formed on the outer peripheral surface. The polygon mirror 14, the ring-shaped leaf spring 21 placed on the polygon mirror 14, and the rotational shaft 47 of the rotating shaft 47 are placed on the leaf spring 21 so as to press the polygon mirror 14 against the upper surface of the flange 46. An aluminum pressing member 22 that is forcibly inserted by press-fitting or shrink fitting at the top, a drive magnet 20 fixed to the skirt portion 19 of the flange 46 with an adhesive or the like, and the drive magnet 20 so as to face each other. The motor core 23 is attached to the outer peripheral surface of the holder 48.

  Since the thrust magnetic bearing is constituted by the magnetic attractive force between the drive magnet 20 and the motor core 23, the rotating body 17 is always kept in a floating state. A metal substrate 13 is fixed to the holder 48, and a brushless motor control circuit (drive element 24, etc.) including a drive magnet 20 and a motor core 23 is mounted on the substrate 13.

  In the optical deflector 6, a herringbone groove is formed on the outer peripheral surface of the rotary shaft 47, and a radial dynamic pressure bearing is configured by the outer peripheral surface of the rotary shaft 47 and the inner peripheral surface of the holder 48.

[Fixed structure of optical deflector]
In this optical polarizer 6, a lower part 49, which is one end of a holder 48, is inserted and fixed in a hole 26 formed in the housing 12. For fixing, one end of the holder 48 may be press-fitted into the hole 26, or a screw hole is formed in an annular protrusion 27 provided on the back surface of the housing 12, and a male screw is screwed into this screw hole. The lower portion 25 of the holder 48 inserted into the 26 may be firmly fixed.

  With this configuration, the optical deflector 6 can be fixed to the housing 12 with high accuracy, using the outer peripheral surface of the holder 48 processed with high accuracy as a reference. Further, in the optical deflector 6, the peripheral edge 50 of the substrate 13 becomes a free end, and other parts of the optical deflector 6 other than the holder 48 are not in contact with the housing 12, so an extra external force from the housing 12 is applied. Absent. For this reason, the axial collapse of the optical deflector 6 can be eliminated or reduced.

A third embodiment according to the present invention will be described below with reference to FIG.
FIG. 4 is a cross-sectional view showing a state where the optical deflector is fixed to the housing. In order to simplify the explanation, in FIG. 4, the sections other than the rotating shaft are shown in cross section.
Only differences from the second embodiment will be described in detail, and the same parts as those of the second embodiment will be denoted by the same reference numerals and description thereof will be omitted.

The main difference between the third embodiment and the second embodiment is that an elastic member 51 such as a sponge is provided between the peripheral edge portion 50 of the substrate 12 and the housing 12.
Even in such a configuration, in the optical deflector 6, since the peripheral edge 50 of the substrate 13 is substantially free, other portions of the optical deflector 6 other than the holder 48 substantially contact the housing 12. Since it cannot be said that it is not, the extra external force from the housing 12 is not added. For this reason, the axial collapse of the optical deflector 6 can be eliminated or reduced. In addition, the vibration generated at the peripheral edge 50 of the substrate 13 can be reduced by the elastic member 51.

  Although not shown, in the optical scanning device shown in the first embodiment, an elastic member 51 may be provided between the peripheral edge 50 of the substrate 12 of the optical deflector 6 and the housing 12 as in the third embodiment. good. Even in this case, the same effect as in the third embodiment can be obtained.

  The above-described embodiments have been illustrated for the purpose of explanation, and the present invention is not limited thereto, and those skilled in the art will recognize from the claims, the detailed description of the invention, and the description of the drawings. As long as it is not contrary to the technical idea of the present invention, it can be changed, deleted and added.

  For example, in the above-described embodiment, the substrate 13 is made of metal. However, the present invention is not limited to this, and the substrate 13 may be made of a material other than metal. The surface of the fixed shaft may be coated with electroless nickel plating or the like.

  In the above-described embodiment, the herringbone-shaped groove is shown as the dynamic pressure generating groove. However, the present invention is not limited to this, and one or a plurality of spiral-shaped grooves or an axial direction (longitudinal direction). It may be a groove formed.

  In the above-described embodiments, the fixed shaft is made of aluminum. However, other metals such as iron, resin, and ceramic may be used as the material.

  The present invention is applied to an optical scanning device used in an image forming apparatus or the like.

1 is a plan view of an optical scanning device according to the present invention (Example 1). (Example 1) which is sectional drawing which shows the state by which the optical deflector was fixed to the housing. (Example 2) which is sectional drawing which shows the state by which the optical deflector was fixed to the housing. (Example 3) which is a sectional view which shows the state where the optical deflector was fixed to the housing. It is sectional drawing of the conventional optical deflector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical scanning device 6 Optical deflector 12 Housing 13 Board | substrate 14 Polygon mirror 16 Fixed axis | shaft 17 Rotating body 48 Holder 50 Peripheral part 51 Elastic member

Claims (4)

At least a fixed shaft,
A rotating body inserted with a gap in the fixed shaft and provided with a polygon mirror;
In an optical scanning device in which an optical deflector comprising:
One end of the fixed shaft is inserted into a hole formed in the housing,
An optical scanning device characterized in that the optical deflector is fixed to the housing so that other parts constituting the optical deflector other than one end of the fixed shaft do not contact the housing. At least the axis of rotation,
A holder for rotatably supporting the rotating shaft;
A rotating body fixed to the rotating shaft and provided with a polygon mirror;
In an optical scanning device in which an optical deflector comprising:
One end of the holder is inserted into a hole formed in the housing,
An optical scanning device characterized in that the optical deflector is fixed to the housing so that other parts constituting the optical deflector other than one end of the holder do not contact the housing. A substrate on which a driving element for rotating the rotating body is mounted is fixed to the fixed shaft or the holder,
The optical scanning device according to claim 1, wherein a peripheral edge portion of the substrate is a free end.   The optical scanning device according to claim 3, wherein an elastic member is provided between a peripheral portion of the substrate and the housing.

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