JP2008003231A - Scanning optical apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the tilt of a shaft caused in a primary assembly on "a motor substrate fixed only around a rotor" which is effective to a thermal shock measures. <P>SOLUTION: A through hole is provided on an optical box for inserting a tool and a motor substrate end part is supported by the inserted tool. Electric components are not mounted on the supported part of the motor substrate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a scanning optical device used in a laser beam printer, a digital copying machine, a digital FAX, and the like, and more specifically, a scanning optical device that scans an irradiated object by deflecting a light beam from a light source. It is about.

  In recent years, a scanning optical device used as an optical system is required to have a smaller and lower cost configuration. As a small and low-cost scanning optical apparatus of this type, as shown in FIG. 6, the circuit board 101 of the deflecting device 112 is formed in a substantially rectangular plate shape, and the length of the board in the short direction is the diameter of the rotor 102 as a rotating member. A configuration is known in which the length is reduced to approximately the same length as the above. In these scanning optical devices, a laser beam generated from a semiconductor laser 103 as a light source is collimated by a collimator lens 104 and condensed by a cylindrical lens 105 into a linear shape on a reflection surface of a rotary polygon mirror 106 as a deflection scanning unit. Then, it passes through the imaging lenses 107 and 108 and is taken out from the window of the optical box 109 toward a rotating drum (not shown). The rotating polygon mirror 106 and the imaging lenses 107 and 108 are accommodated in an optical box 109 that is a casing, and a deflecting device 112 that rotates the rotating polygon mirror 106 is fixed to the bottom surface of the optical box 109 with screws 110 a and 110 b.

  A deflecting device 112 having a rotating polygon mirror 106 is a rotating member including a rotating shaft 111 supported on an optical box 109 via a bearing, a yoke coupled to a washer integral with the rotating shaft 111, and a rotor magnet. A rotor 102 and a stator coil fixed to a circuit board 101 integral with the bearing housing are included. When the stator coil is excited by the drive current supplied from the drive circuit on the circuit board 101, it rotates at a high speed together with the rotary polygon mirror 106, and deflects and scans the light beam applied to the rotary polygon mirror 106 as described above. To do.

  In addition, the method of attaching the deflecting device to the optical box in the scanning optical device includes the storage environment of the scanning optical device and the temperature rise in the image forming apparatus during operation, particularly the rotating shaft of the deflecting device generated by a heat cycle or thermal shock. In order to reduce the inclination of the image and prevent the image quality from deteriorating, there is a configuration in which a fixing portion to be attached to the optical box of the deflecting device is arranged in the vicinity of the rotor which is a rotating member, and only two fixing portions are provided.

As another conventional example, Patent Document 1 can be cited.
JP2003-295099

  However, according to the conventional technique described above, in order to reduce the size of the scanning optical device, the circuit board of the deflecting device is made substantially rectangular, and the substrate length in the short direction is substantially equal to the diameter of the rotor that is the rotating member. Although the length is reduced, the posture when attaching the deflecting device to the optical box may become unstable if the size of the circuit board is reduced. Furthermore, the configuration in which the fixing unit of the deflecting device is provided at two locations in the vicinity of the rotor, which is a rotating member, has a short distance between the fixing units and may cause an unstable posture when the deflecting device is attached to the optical box. Is done. If the position of the deflection device becomes unstable and the screw is tightened with the circuit board tilted, the deflection device will remain tilted even after the screw has been tightened, and the rotation axis of the deflection device and the reflecting surface of the rotary polygon mirror will remain. An inclination is generated to cause a distortion in a desired beam shape, or a scanning line is bent on the irradiated body, thereby deteriorating the image quality.

  Therefore, the present invention has been made in view of the above-mentioned unsolved problems of the prior art, and even when the rotating substrate of a substantially rectangular small-sized deflecting device is fixed to the optical box at two locations, the deflecting device is mounted on the optical box. A scanning optical device that maintains a constant posture when attached to the optical device, prevents the deflection device from being fixed to the optical box with the rotation shaft tilted, and provides stable optical characteristics and good printing accuracy. Is intended to provide.

In order to achieve the above object, the invention according to this question is
A rotating polygon mirror that deflects and scans a light beam emitted from a light source, a rotating member that rotates together with the rotating polygon mirror, a deflecting device having a circuit board for driving the rotating member, and a mounting device for the deflecting device In the scanning optical device having an optical box provided with two fixing portions in the vicinity of the rotating member, the optical box is located away from the rotating member, and a through hole is provided on a surface facing the circuit board. The circuit board located above the through hole is provided with a non-circuit mounting portion on which no electrical component or circuit is mounted.

  Further, a receiving member for temporarily supporting the deflection device may be inserted from the through hole, and the deflection device may be supported by the receiving member and the fixing portion, and then fastened to the fixing portion with a screw.

  Moreover, the said deflection | deviation apparatus is good to fasten with a screw | thread to the fixed part of the previous period, after pinching | pinching with the press means and the said receiving member which press the said non-circuit mounting part.

  Furthermore, the receiving member can adjust the relative height to the fixed portion, and the deflection device may be attached to the fixed portion while detecting the amount of inclination of the rotating member.

  As described above, according to the present invention, when the deflection device is attached to two fixed portions provided in the optical box, it is easy to insert the receiving member of the deflection device through the through hole provided in the optical box. In addition, it is possible to provide a third support portion to the deflecting device supported at two locations with a simple configuration. As a result, the posture of the deflecting device can be stabilized to prevent the rotation shaft of the deflecting device from being tilted, and a desired beam shape can be formed on the irradiated object, resulting in stable optical characteristics and high accuracy. The effect that it is possible to provide a scanning optical device capable of obtaining a good print quality can be expected.

  Next, details of the present invention will be described in accordance with the description of the embodiments.

  Embodiments of the present invention will be described with reference to the drawings. However, the dimensions, materials, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Moreover, in the code | symbol of each figure, the same code | symbol represents the same member.

(Embodiment of the present invention)
1a and 1b illustrate a scanning optical device according to an embodiment of the present invention.

  A light beam generated from a semiconductor laser (not shown), which is a light source, is collimated by a collimator lens 6, is condensed linearly on the reflecting surface of the rotary polygon mirror 1 by a cylindrical lens 7, and passes through imaging lenses 2 and 3. Then, it is taken out from the window of the optical box 4 toward the rotating drum. The scanning light that forms an image on the photosensitive member on the rotating drum forms an electrostatic latent image along with the main scanning by the rotary polygon mirror 1 and the sub scanning by the rotation of the rotating drum. The rotating polygon mirror 1 and the imaging lenses 2 and 3 are accommodated in an optical box 4 which is a casing, and the light source unit 5 holding the semiconductor laser is assembled to the side wall of the optical box 4 or the like. A deflection device 8 that rotationally drives the rotary polygon mirror 1 includes a rotary shaft 9 supported via a liquid bearing (not shown), a rotor 10 that is a rotary member coupled to a washer integral with the rotary shaft 9, and The circuit board 11 is integrated with the bearing housing. The circuit board 11 is a substantially rectangular plate having a control part for mounting a driving IC 12 for controlling rotation, a connector 13 and the like, and screws 16a, fixed parts 15a, 15b provided at the bottom of the optical box 4, It stops at 16b. Further, the fixing portions 15a and 15b are provided in the vicinity of the rotor 10 that is a rotating member, and each is provided in the optical box 4 as a circular seating surface. On the other hand, there is a through hole 14 at a position away from the vicinity of the rotor 10 at the bottom of the optical box 4, and an electrical component or the like is provided at a position corresponding to the through hole 14 of the circuit board 11 of the deflection device 8. A non-circuit mounting part 21 in which no circuit part or the like is arranged is provided. When attaching the deflection device 8 to the optical box 4, first, the receiving member 17 that supports the deflection device 8 is inserted through the through hole 14. The circuit board 11 of the deflecting device 8 is supported at three locations of the fixing portions 15a and 15b and the receiving member 17, and is fixed to the fixing portions 15a and 15b with screws 16a and 16b. evacuate.

  When the deflection device 8 is fixed only at the two locations 15a and 15b in the vicinity of the rotor 10 that is a rotating member, the deflection device 8 is inclined. The phenomenon of tilting will be described with reference to FIGS. 2a and 2b.

  When the deflection device 8 having the substantially rectangular circuit board 11 is attached to two places of the fixing portions 15a and 15b provided in the optical box 4, the deflection device 8 has a short distance L between the fixing portions 15a and 15b, Further, since the circuit board 11 has a substantially rectangular plate shape, the deflection in the direction of the arrow A occurs in the portion 15c where the receiving portion is not provided under the circuit board 11 due to the weight of the deflecting device 8. The tilt in the direction of arrow A causes the rotation shaft 9 of the deflecting device 8 to be tilted, and the screws 16a and 16b are fastened with the tilt remaining on the rotation shaft 9, and after the screws 16a and 16b are fastened. Variations occur in the inclination of the rotation shaft 9. Further, at the end of fastening the screws 16a and 16b, the circuit board 11 is rotated together with the screws 16a and 16b so that the bearing holding portion 18 and the fitting portion 19 of the optical box interfere with each other. Directional force F is generated, and accordingly, the rotation shaft 9 of the deflecting device 8 is tilted. The generated tilt of the rotating shaft 9 causes the spot shape of the laser beam to be broken and causes the scanning line to bend, and the variation in the tilt of the rotating shaft 9 causes the quality of the scanning optical apparatus to become unstable.

  Therefore, the following effects can be obtained by using the above-described configurations shown in FIGS. 1a and 1b.

  In the configuration of FIGS. 1a and 1b, when the deflection device is attached to the optical box, the circuit board of the deflection device can be easily temporarily supported at three locations. As shown in FIG. At the same time as the distance L between the supporting points to be supported is increased, the circuit board 11 is received on the surface M formed by connecting the supporting points, so that the posture of the deflecting device 8 is stabilized and the rotating shaft 9 of the deflecting device 8 is fixed. The generated tilt can be reduced. FIG. 3b shows the result of measuring the amount of tilt of the rotating shaft of the deflecting device that occurs when the deflecting device is attached to the optical box with an autocollimator. It can be seen that there is a difference between the amount of inclination of the rotation axis of the deflecting device and its variation when the configuration of FIGS. 1a and 1b of the present embodiment is used and when the configuration of the conventional example of FIG. 6 is used. Therefore, it was confirmed that when the embodiment of the present invention is used, the tilt of the rotation shaft of the deflecting device can be reduced and stabilized.

  Next, a modification of the embodiment of the present invention will be described with reference to FIG.

  In this modification, in addition to the configuration of the embodiment shown in FIGS. 1 a and 1 b, a pressing rod 20 is provided on the upper surface side of the circuit board 11. The pressing bar 20 is disposed so as to be coaxially opposed to the receiving member 17 that supports the deflecting device, is driven down in the vertical direction with respect to the circuit board 11, and the circuit board 11 is sandwiched between the receiving member 17 below the circuit board. It has become. Further, the pressing bar 20 presses the non-circuit mounting portion 21 on which the circuit of the circuit board 11 is not mounted, thereby biasing the circuit board 11. The number of pressing bars 20 and receiving members 17 is not limited to one, and a plurality of pressing bars 20 and receiving members 17 may be provided.

  When this modification is used, by holding the circuit board 11 between the pressing rod 20 and the receiving member 17 and fastening the screws 16a and 16b, the rotation at the time of screw fastening is prevented, and the radial direction It is possible to prevent the force F from being applied to the bearing holding member 18, to further prevent the rotation shaft 9 from being tilted, to obtain a desired spot shape and scanning line, and to improve the image quality. be able to.

  Furthermore, a second modification of the embodiment of the present invention will be described.

  When the deflecting device 8 is attached to the optical box 4, as described with reference to FIGS. 1a and 1b, first, the receiving member 17 that supports the deflecting device 8 is inserted through the through hole 14, and the circuit board 11 of the deflecting device 8 is fixed to the fixing unit. It supports in three places, 15a, 15b, and the receiving member 17. FIG. Then, as shown in FIG. 5, before the screws 16a and 16b are fastened, the amount of change in the inclination of the rotating shaft 9 during rotation of the deflecting device 8 is set to at least one of the rotary polygon mirror 1, the rotor unit 10, and the rotating shaft 9. The part which becomes the mirror surface of the upper surface of is quantitatively measured by the autocollimator 22. By measuring, the inclination amount and the inclination direction of the rotating shaft 9 are determined, and the receiving member is driven up and down to adjust the relative height with the fixing portions 15a and 15b. Before the screws 16a and 16b are fastened, the tilt amount of the rotary shaft 9 is reduced to create a state where the posture of the deflecting device 8 is stabilized, and then the screws 16a and 16b are fastened. As a result, the inclination of the rotation shaft 9 can be reduced, and variations in the inclination direction of the rotation shaft 9 can be stabilized. In particular, the tilt of the rotary shaft 9 is substantially in the direction of the bisector T between the laser incident direction on the rotary polygon mirror 1 and the optical axes of the imaging lenses 2 and 3, which greatly affects the tilt of the rotary shaft 9. The effect can be sufficiently exhibited by making the posture of the deflecting device constant by using the receiving member so as not to occur. Further, after the deflecting device 8 is attached, the receiving member 17 is retracted from the through hole 14, the amount of inclination of the rotating shaft 9 is measured by the autocollimator 22, and the inclination direction is automatically determined, thereby preventing the extraction of defective products. In addition, the cause can be quickly dealt with, and the quality can be maintained and stabilized.

FIGS. 5A and 5B are diagrams illustrating an embodiment of the present invention. FIGS. FIGS. 9A and 9B are diagrams illustrating the inclination of the rotation shaft generated by a conventional deflection device fixing method in comparison with the present invention. FIGS. The figure explaining embodiment of this invention. The figure which showed the result of having examined the inclination amount of the author's rotating shaft. FIGS. 9A and 9B are diagrams illustrating a first modification of the embodiment of the present invention. The figure which showed the 2nd modification in embodiment of this invention. The figure explaining the prior art example.

Explanation of symbols

4 Optical box 8 Deflector 9 Rotating shaft 10 Rotating member (rotor)
DESCRIPTION OF SYMBOLS 11 Circuit board 14 Through-hole 15a, 15b Fixing part 17 Receiving member 20 Pressing member 21 Circuit cost mounting part 22 Autocollimator

Claims (4)

A rotating polygon mirror that deflects and scans a light beam emitted from a light source, a rotating member that rotates together with the rotating polygon mirror, a deflecting device having a circuit board for driving the rotating member, and a mounting device for the deflecting device In a scanning optical apparatus having an optical box provided with two fixed portions in the vicinity of the rotating member,
The optical box is located away from the rotating member, and a through hole is provided on a surface facing the circuit board, and electrical components and circuits are mounted on the circuit board located above the through hole. A non-circuit mounting portion that is not provided is provided.   A receiving member for temporarily supporting the deflecting device is inserted from the through hole, the deflecting device is supported by the receiving member and the fixing portion, and then fastened to the fixing portion with a screw. The scanning optical device according to claim 1.   3. The scanning according to claim 1, wherein the deflecting device is clamped by a pressing unit that presses the non-circuit mounting portion and the receiving member, and then fastened to the fixing portion by a screw. Optical device.   The receiving member is capable of adjusting a relative height with the fixed portion, and the deflection device is attached to the fixed portion while detecting an inclination amount of the rotating member. The scanning optical device according to any one of claims 1 to 3.

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