JP2006123478A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate position adjustment and fixation of a collimator lens in a state with a housing member of a unit fixed to a jig in an image forming apparatus equipped with the laser scan unit. <P>SOLUTION: A circuit board 32 with a laser diode 31 mounted, and the collimator lens 33 are directly attached to the housing member 42. At the same time, an opening 43 for connecting a connector 41 to a circuit board 40 is formed on an extension line which connects the laser diode 31 and the collimator lens 33 of the housing member 42. Before a cylinder lens 35 and a polygon mirror 36 are incorporated in the housing member 42, the laser diode 31 is made to emit light. Laser beams passing the collimator lens 33 are ejected to the outside of the housing member 42 from the opening 43, and measured by a predetermined measuring instrument. Based on the measured value, a position of the collimator lens 33 is finely adjusted and fixed by a photo-curing resin. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus including a laser scan unit that forms a latent image by irradiating a surface of a photosensitive drum with a laser beam while scanning.

  Conventionally, in an image forming apparatus provided with a laser scanning unit, it is usually necessary for exposure of a photosensitive drum by a collimator lens, a cylinder lens, and a polygon mirror arranged in series on the optical axis of a laser diode as a light source. Scanning light is generated. In order to emit parallel light from the collimator lens, it is necessary to accurately position the laser diode at the focal point of the collimator lens. Therefore, the collimator lens is configured so that the position in the optical axis direction can be adjusted with respect to the laser diode. ing.

  The position of the collimator lens is adjusted by causing a laser diode to emit light and measuring the laser beam that has passed through the collimator lens with a predetermined lateral instrument. However, in a state where each optical component described above is mounted on the housing member of the laser scan unit, the cylinder lens and the polygon are arranged on the optical path of the laser beam that has passed through the collimator lens due to the arrangement of the collimator lens, the cylinder lens, and the polygon mirror. Since the mirror is positioned, the transmitted beam cannot be measured with a side plate provided outside the housing member. Therefore, in a conventional image forming apparatus, a collimator base member for holding a laser diode and a collimator lens is provided, and after the collimator base member is mounted on a predetermined measurement jig and the position of the collimator lens is adjusted, The collimator lens is fixed to the collimator base member with an adhesive. Then, the collimator base member to which the collimator lens is fixed is removed from the measurement jig and attached to the housing of the laser scan unit.

  On the other hand, the cylinder lens also needs to be adjusted in the optical axis direction with respect to the polygon mirror. The position of the collimator lens is adjusted by causing the laser diode to emit light while the housing of the laser scan unit incorporating the collimator base member, cylinder lens, polygon mirror, fθ lens and mirror member is mounted on a predetermined measuring jig. The laser beam reflected by the member to the outside of the housing member is measured by a predetermined lateral instrument.

  As described above, in the conventional image forming apparatus, the position of the collimator lens is adjusted in a state where the laser diode and the collimator lens are incorporated in the collimator base member, and the collimator base member, the cylinder lens, the polygon mirror, etc. are incorporated in the housing member. To adjust the cylinder lens position. Therefore, it takes time to fix the collimator base member to the jig dedicated to the base member when adjusting the position of the collimator lens, and to fix the housing member to the jig dedicated to the housing member when adjusting the position of the cylinder lens. However, this causes a decrease in productivity of the image forming apparatus, which is a factor that increases the manufacturing cost.

Patent Document 1 discloses a laser scan unit in which a positioning member for positioning an fθ lens is formed integrally with a rib of a housing member. Patent Document 2 has a configuration in which a laser diode and a collimator lens are mounted on an optical case equivalent to the collimator base member, and an optical case, a cylinder lens, a polygon mirror, and the like are mounted on an optical base equivalent to the housing member. It is shown. Patent Document 3 discloses a configuration in which a laser diode, a lens, and a mirror are mounted on a base member, and a polygon mirror and an fθ lens are mounted on a housing member. Even if the techniques disclosed in any of these patent documents are applied, the above-described problems cannot be solved.
JP-A-10-2137770 JP-A-10-239621 JP 2000-147399 A

  The present invention has been made in order to solve the above-described problems, and improved the productivity by making it possible to easily adjust and fix the position of the collimator lens while the housing member is fixed to a jig. An object is to provide an image forming apparatus.

  In order to achieve the above object, the invention according to claim 1 is a photoconductor drum having a photoconductor coated on the surface, a charging means for uniformly charging the surface of the photoconductor drum, and a laser beam scanned on the surface of the photoconductor. Exposure means for forming a latent image by irradiation, developing means for forming a toner image by attaching toner to a portion of the surface of the photosensitive member where the latent image is formed, and development in the rotational direction of the photosensitive drum A transfer means provided to face the surface of the photosensitive drum at a predetermined transfer position downstream of the means, and for transferring the toner image formed on the surface of the photosensitive drum onto the recording paper; and a toner image In the image forming apparatus comprising a fixing means for fixing the toner image on the recording paper by applying predetermined heat and pressure to the recording paper on which the toner is transferred, and a control means for controlling each of the above parts, the exposure means uses a laser beam. Emit A laser diode, a first circuit board on which the laser diode is mounted, a collimator lens that collimates the laser beam emitted from the laser diode, and a laser beam collimated by the collimator lens is focused only in the main scanning direction A cylinder lens for reflecting, a polygon mirror for reflecting the laser beam focused only in the main scanning direction by the cylinder lens so as to scan in the main scanning direction, and an fθ lens for transmitting the laser beam reflected by the polygon mirror, A second circuit board on which a mirror member for reflecting the laser beam transmitted through the fθ lens toward the surface of the photosensitive drum, a driving means for rotationally driving the polygon mirror, and the second circuit board are mounted. And connectors for connecting the control means and each of these parts And a laser diode, a collimator lens, a cylinder lens, and a polygon mirror are arranged on a substantially straight line, and the first circuit board and the collimator lens on which the laser diode is mounted are on the housing member. The housing member has an opening for connecting the connector to the second circuit board on the extension line connecting the laser diode and the collimator lens. The collimator lens includes the cylinder lens and the polygon mirror. Before being incorporated into the member, the photocurable resin is applied and held at a predetermined position on the housing member. In this state, the laser diode emits light, and the laser beam transmitted through the collimator lens is emitted from the opening of the housing member. Do not measure this laser beam. Then, the position in the optical axis direction is finely adjusted, and then fixed on the housing member by irradiating and curing the light curable resin. The cylinder lens incorporates a polygon mirror, an fθ lens and a mirror member. After that, the photocurable resin is applied and held at a predetermined position on the housing member. In this state, the laser diode emits light, and the laser beam reflected from the housing member by the mirror member is measured. However, by finely adjusting the position, it is positioned in the optical axis direction, and then fixed on the housing member by irradiating and curing the light curable resin, whereby the collimator lens and the cylinder lens The position of can be easily adjusted and fixed.

  According to a second aspect of the present invention, there is provided a photosensitive drum having a surface coated with a photosensitive member, a charging unit for uniformly charging the surface of the photosensitive drum, and a latent image formed by irradiating the surface of the photosensitive member while scanning a laser beam. On the surface of the photosensitive drum at a predetermined transfer position downstream of the developing means in the rotational direction of the photosensitive drum. A transfer unit that is provided so as to be opposed to transfer the toner image formed on the surface of the photosensitive drum onto the recording paper, a fixing unit that fixes the transferred toner image on the recording paper, and controls each of the above parts In the image forming apparatus including the control unit, the exposure unit includes a laser diode that emits a laser beam, a collimator lens that collimates the laser beam emitted from the laser diode, A circuit board mounted with a polygon mirror for reflecting the laser beam collimated by the collimator lens so as to scan in the main scanning direction, a driving means for rotationally driving the polygon mirror, and the circuit board and the control means. It has a connector for connection and a housing member in which each of these components is incorporated. The laser diode and the collimator lens are directly mounted on the housing member, and the housing member is on an extension line connecting the laser diode and the collimator lens. The collimator lens emits a laser diode before the polygon mirror is incorporated into the housing member, and the laser beam transmitted through the collimator lens is emitted from the opening to the housing member. Let the laser beam pass outside. By measuring its optical axis direction position is finely adjusted, thereby, in which a readily adjustable position of the collimator lens.

  According to the first aspect of the present invention, the first circuit board on which the laser diode is mounted and the collimator lens are mounted directly on the housing member, and an opening is provided on the extension line connecting the laser diode and the collimator lens. Therefore, the laser beam transmitted through the collimator lens when adjusting the collimator lens can be emitted from the opening to the outside of the housing member. Therefore, by measuring the transmitted beam emitted from the opening, it is possible to position the collimator lens with the housing member mounted on the jig. Thereafter, the cylinder lens can be positioned by incorporating the cylinder lens and the polygon mirror into the housing member without removing the housing member from the jig. Thereby, the manufacturing process of the laser scanning unit is simplified, and the manufacturing cost of the image forming apparatus can be reduced. Further, since the connector is inserted into the opening through which the laser beam is passed when adjusting the position of the collimator lens, there is no possibility that light leaks from the opening to the outside of the housing during operation of the image forming apparatus. In addition, since the collimator base member for mounting the laser diode and the collimator lens required in the conventional image forming apparatus is not necessary, the number of parts of the laser scan unit and the assembly man-hours can be reduced. Manufacturing costs can be reduced.

  According to the invention of claim 2, since the laser diode and the collimator lens are mounted directly on the housing member and the opening is provided on the extension line connecting the laser diode and the collimator lens, the collimator lens is adjusted. The laser beam transmitted through the collimator lens can be emitted from the opening to the outside of the housing member. Therefore, by measuring the transmitted beam emitted from the opening, it is possible to position the collimator lens with the housing member mounted on the jig. Thereby, the manufacturing process of the laser scanning unit is simplified, and the manufacturing cost of the image forming apparatus can be reduced. Further, since the connector is inserted into the opening through which the laser beam is passed when adjusting the position of the collimator lens, there is no possibility that light leaks from the opening to the outside of the housing during operation of the image forming apparatus. In addition, a collimator base member for mounting a laser diode and a collimator lens, which is necessary for a conventional image forming apparatus, is not necessary, so that the number of parts and the number of assembly steps can be reduced, and the manufacturing cost of the image forming apparatus is reduced. It becomes possible to do.

  A laser beam printer according to the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 shows a configuration example of the laser beam printer 1. The laser beam printer 1 includes a photosensitive drum 2 having a photosensitive member coated on the surface thereof, a cleaner 3 sequentially disposed around the photosensitive drum 2 from the upstream side to the downstream side in the rotation direction A, and a charger. (Charging unit) 4, laser scanning unit (exposure unit) 5, developing brush (developing unit) 6, transfer roller (transfer unit) 7, and downstream of the transfer roller 7 in the conveyance direction B of the recording paper P An arranged fixing roller (fixing means) 8, a paper feed tray 9 loaded with recording paper P, a paper discharge tray 10 on which printed recording paper P is deposited, and a recording paper P for conveying A recording paper conveyance mechanism (conveyance means) 11 and a control unit 12 that controls each part of the apparatus are configured. Each of the above components is mounted on a metal frame 13 disposed on the bottom of the laser beam printer 1 or the like. The metal frame 13 is mounted with a cabinet 14 that covers each of the above components and forms the exterior of the laser beam printer 1, and the upper portion thereof is for removing the recording paper P jammed in the recording paper transport mechanism 11 or A door member 15 for exchanging a toner cartridge 17 described later is provided so as to be freely opened and closed.

  The cleaner 3 removes toner and paper dust before one stroke (one rotation) adhering to the surface of the photosensitive drum 2 and cleans the drum surface. The charger 4 uniformly charges the surface of the photosensitive drum 2 cleaned by the cleaner 3. The laser scan unit 5 forms a latent image by irradiating the surface of the photosensitive drum 2 charged by the charger 4 while scanning the laser beam L. The laser scan unit 5 is supplied with power by a power supply device (not shown), and a light emission voltage for light emission of the laser diode is applied. The developing brush 6 is attached to a toner cartridge 17 filled with toner, and forms a toner image by attaching toner to a portion of the surface of the photosensitive drum 2 where a latent image is formed. The transfer roller 7 is provided so as to oppose the surface of the photosensitive drum 2, and charges the surface of the recording paper P while pressing the recording paper P against the surface of the photosensitive drum 2. The formed toner image is transferred onto the recording paper P. A transfer voltage for charging the surface of the recording paper P is applied to the transfer roller 7 from a power supply device. The fixing roller 8 sandwiches the recording paper P together with the rollers 18 arranged at opposite positions, and applies heat and pressure to the recording paper P to fix the toner. Heat for fixing the toner is supplied from a heater (for example, a halogen lamp) built in the fixing roller 8. A fixing voltage generated by a power supply device is applied to the heater.

  The recording paper transport mechanism 11 includes a pickup roller 11a, transport rollers 11b, 11c, and 11d, a paper stacking plate 20 that is disposed in the vicinity of the paper feed tray 9, and presses the loaded recording paper P against the pickup roller 11a. A coil spring 21 or the like for urging the paper stacking plate 20 toward the pickup roller 11a is provided.

  A recording paper placement surface 23 on which the recording paper P is placed is continuously formed by the paper feed tray 9 and the paper stacking plate 20. When the user inserts a plurality of recording papers P in a stacked state from the side of the paper feed tray 9, the recording papers P are placed on the recording paper placement surface 23.

  The pickup roller 11a is disposed to face the recording paper placement surface 23, and sends the uppermost recording paper P placed on the recording paper placement surface 23 to the transport roller 11b. The transport roller 11b sends the recording paper P sent out by the pickup roller 11a to the transport roller 11c. The transport rollers 11c and 11d are arranged so as to face each other between the transport roller 11b and the transfer roller 7, and transport the recording paper P sent out by the transport roller 11b to the transfer position.

  2 and 3 show the configuration of the laser scan unit 5. The laser scan unit 5 includes a laser diode 31 that emits a laser beam, a first circuit board 32 that applies a driving voltage to the laser diode 31, and a collimator lens 33 that collimates the laser beam emitted from the laser diode 31. A slit 34 that narrows the laser beam that has been collimated by the collimator lens 33 and narrows it, a cylinder lens 35 that focuses the laser beam that has passed through the slit 34 only in the main scanning direction, and a beam that has been focused by the cylinder lens 35 A polygon mirror 36 that reflects the laser beam so as to scan in the main scanning direction, an fθ lens 37 that transmits the laser beam reflected by the polygon mirror 36, and a laser beam that passes through the fθ lens 37 is the surface of the photosensitive drum 2. Mirror member reflecting toward 38, a second circuit board 40 on which a drive motor (drive means) 39 for rotationally driving the polygon mirror 36 is mounted, a connector 41 for connecting the second circuit board 40 and the control unit 12, A box-shaped housing member 42 in which these components are incorporated is provided.

  The laser diode 31 is mounted on the first circuit board 32. The first circuit board 32, the collimator lens 33, the slit 34, the cylinder lens 35, the second circuit board 40, the fθ lens 37, and the mirror member 38 are directly mounted on the housing member 42. The collimator lens 33, the cylinder lens 35, and the polygon mirror 36 are disposed on the optical axis of the laser diode 31. Further, on the side surface of the housing member 42 adjacent to the second circuit board 40, the connector 41 is placed on the extension line L0 (see FIG. 3) connecting the laser diode 31 and the collimator lens 33 to the second circuit board. An opening 43 for connection to 40 is provided.

  Next, the assembly process of the laser scan unit 5 will be described. In assembling the laser scan unit 5, the housing member 42 is mounted on a predetermined jig (see FIG. 4). At a position corresponding to the opening 43 of the housing member 42 mounted on the jig, when adjusting the position of the collimator lens 33, a lateral instrument for measuring the laser beam transmitted through the collimator lens 33 (see FIG. 4). ) Is provided on the optical axis of the reflected beam by the mirror member 38, and a side plate (not shown) for measuring the reflected beam when adjusting the position of the cylinder lens 35 is provided. Yes. Each component constituting the laser scan unit 5 includes a first circuit board 32 (laser diode 31), a collimator lens 33, a slit 34, a cylinder lens 35, a second circuit board 40 (polygon mirror 36), an fθ lens 37, and the like. The mirror members 38 are assembled in the housing member 42 in the order. After the first circuit board 32 and the collimator lens 33 are assembled, the position of the collimator lens 33 with respect to the laser diode 31 is adjusted before the slit 34, the cylinder lens 35, the second circuit board 40, and the like are incorporated. Then, the position of the collimator lens 33 is adjusted, and then the slit 34, the cylinder lens 35, the second circuit board 40, the fθ lens 37, and the mirror member 38 are incorporated, and then the position of the cylinder lens 35 with respect to the polygon mirror 36 is adjusted. Is done.

  Hereinafter, the process of adjusting the position of the collimator lens 33 will be described with reference to FIG. The collimator lens 33 is held by the collimator holding portion 44 on the housing member 42 before the cylinder lens 35 and the second circuit board 40 are assembled into the housing member 42. At this time, a photo-curing resin before curing is applied to the contact portion between the collimator lens 33 and the collimator holding portion 44. When the laser diode 31 is caused to emit light in this state, the laser beam that has passed through the collimator lens 33 passes through the opening 43 and is emitted to the outside of the housing member 42, and is provided in the vicinity of the opening 43 described above. Measured by. Then, the position of the collimator lens 33 in the optical axis direction is finely adjusted based on the value measured by the lateral instrument. When the adjustment of the position of the collimator lens 33 is completed, the collimator lens 33 is fixed at an appropriate position with respect to the laser diode 31 by irradiating the photocurable resin with light and curing the resin.

  Hereinafter, the process of adjusting the position of the cylinder lens 35 will be described. The cylinder lens 35 is incorporated in the housing member 42 after the photo-curing adhesive applied to the collimator lens 33 is cured, and a photo-curing resin before curing is applied to the contact portion with the cylinder holding portion 45. It is held by a cylinder holding part 45 on the housing member 42. After the second circuit board 40, the fθ lens 37, and the mirror member 38 are assembled, when the polygon mirror 36 is appropriately rotated while the laser diode 31 emits light, the laser beam reflected by the mirror member 38 is reflected on the housing member. It is emitted outside. This reflected laser beam is measured by a measuring instrument provided on the optical axis. Then, the position of the cylinder lens 35 in the optical axis direction is finely adjusted based on the value measured by the side plate. When the adjustment of the position of the cylinder lens 35 is completed, the cylinder lens 35 is fixed at an appropriate position on the housing member 42 by irradiating the photocurable resin with light and curing the same as described above.

  As described above, according to the laser beam printer 1 of the present embodiment, the first circuit board 32 on which the laser diode 31 is mounted and the collimator lens 33 are mounted directly on the housing member 42, and Since the opening 43 is provided on the extension line L0 connecting the collimator lens 33, the laser beam transmitted through the collimator lens 33 can be emitted from the opening 43 to the outside of the housing member 42 when the collimator lens 33 is adjusted. it can. Therefore, by measuring the transmitted beam emitted from the opening 43, the collimator lens 33 can be positioned with the housing member 42 mounted on the jig. After that, the cylinder lens 35 and the polygon mirror 36 and the like can be incorporated into the housing member 42 without positioning the housing member 42 from the jig to position the cylinder lens 35. Thereby, the manufacturing process of the laser scan unit 5 is simplified, and the manufacturing cost of the laser beam printer 1 can be reduced. Further, since the connector 41 is inserted into the opening 43 through which the laser beam is passed when the position of the collimator lens 33 is adjusted, light may leak from the opening 43 to the outside of the housing member 42 when the laser beam printer 1 is operated. Nor. Further, since the collimator base member for mounting the laser diode 31 and the collimator lens 33 required in the conventional laser beam printer 1 is not necessary, the number of parts of the laser scan unit 5 and its assembly man-hour can be reduced. The manufacturing cost of the laser beam printer 1 can be reduced.

  The present invention is not limited to the configuration of the above-described embodiment, and various modifications can be made. For example, the laser scan unit 5 is not limited to the laser beam printer 1, and an image of a laser scan type copying machine or the like. It can be widely applied to forming apparatuses. Further, the collimator lens 33, the cylinder lens 35, the polygon mirror 36, and the opening 43 only have to be arranged on the optical axis of the laser diode 31, and the arrangement of each optical system component is limited to that shown in FIG. Absent. Further, instead of the fθ lens 37, a scanning lens having an equivalent function may be used.

The figure which shows the structure of the laser beam printer by one Embodiment of this invention. The perspective view which shows the structure of the laser scanning unit applied to the laser beam printer. The side view of the housing member of the laser scanning unit. The top view which shows a mode that the position adjustment of a collimator lens is performed in the laser scanning unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser beam printer 2 Photosensitive drum 4 Charger (charging means)
5 Laser scan unit (exposure means)
6 Developing brush (Developing means)
7 Transfer roller (transfer means)
8 Fixing roller (fixing means)
9 Paper feed tray 11 Recording paper transport mechanism (transport means)
12 Control unit (control means)
31 Laser diode 32 First circuit board 33 Collimator lens 35 Cylinder lens 36 Polygon mirror 37 fθ lens 38 Mirror member 39 Drive motor (drive means)
40 Second circuit board 41 Connector 42 Housing member 43 Opening

Claims (2)

A photoreceptor drum having a photoreceptor coated on the surface;
Charging means for uniformly charging the surface of the photosensitive drum;
Exposure means for forming a latent image by irradiating the surface of the photoconductor while scanning with a laser beam;
Developing means for forming a toner image by attaching toner to a portion of the surface of the photoreceptor where a latent image is formed;
A toner image formed on the surface of the photosensitive drum is recorded at a predetermined transfer position downstream of the developing unit in the rotational direction of the photosensitive drum so as to face the surface of the photosensitive drum. Transfer means for transferring onto paper,
Fixing means for applying a predetermined heat and pressure to the recording paper on which the toner image has been transferred to fix the toner image on the recording paper;
In an image forming apparatus provided with a control unit that controls each of the above-described units,
The exposure means includes a laser diode that emits a laser beam, a first circuit board on which the laser diode is mounted, a collimator lens that collimates the laser beam emitted from the laser diode, and is collimated by the collimator lens. A cylindrical lens that focuses the laser beam focused only in the main scanning direction, a polygon mirror that reflects the laser beam focused only in the main scanning direction by the cylinder lens so as to scan in the main scanning direction, and a reflection by the polygon mirror An fθ lens that transmits the laser beam that has been transmitted, a mirror member that reflects the laser beam transmitted through the fθ lens toward the surface of the photosensitive drum, and a driving unit that rotationally drives the polygon mirror are mounted. A second circuit board, the second circuit board and the A connector for connecting the control means, and a box-shaped housing member in which each of these components is incorporated;
The laser diode, collimator lens, cylinder lens and polygon mirror are arranged on a substantially straight line,
The first circuit board on which the laser diode is mounted and the collimator lens are mounted directly on the housing member,
The housing member has an opening for connecting the connector to the second circuit board on an extension line connecting the laser diode and the collimator lens;
The collimator lens is held at a predetermined position on the housing member in a state where a photo-curing resin is applied before the cylinder lens and the polygon mirror are incorporated in the housing member, and in this state, the laser diode is The laser beam that has been emitted and transmitted through the collimator lens is allowed to pass through the opening to the outside of the housing member, and the position of the optical axis direction is finely adjusted while measuring the laser beam that has passed therethrough. It is fixed on the housing member by irradiating light to the curable resin and cured,
The cylinder lens is held at a predetermined position on the housing member in a state in which a photo-curing resin is applied after the polygon mirror, the fθ lens, and the mirror member are incorporated, and the laser diode emits light in that state. The position is adjusted in the optical axis direction by finely adjusting the position of the laser beam reflected outside the housing member by the mirror member, and then the photocurable resin is irradiated with light. Fixed on the housing member by curing,
Thus, the image forming apparatus is characterized in that the positions of the collimator lens and the cylinder lens can be easily adjusted and fixed. A photoreceptor drum having a photoreceptor coated on the surface;
Charging means for uniformly charging the surface of the photosensitive drum;
Exposure means for forming a latent image by irradiating the surface of the photoconductor while scanning with a laser beam;
Developing means for developing a toner image formed on the surface of the photoreceptor;
A toner image formed on the surface of the photosensitive drum is recorded at a predetermined transfer position downstream of the developing unit in the rotational direction of the photosensitive drum so as to face the surface of the photosensitive drum. Transfer means for transferring onto paper,
Fixing means for fixing the transferred toner image on the recording paper;
In an image forming apparatus provided with a control unit that controls each of the above-described units,
The exposure means scans a laser diode that emits a laser beam, a collimator lens that collimates the laser beam emitted from the laser diode, and a laser beam collimated by the collimator lens in the main scanning direction. A polygon mirror to be reflected, a circuit board on which driving means for rotationally driving the polygon mirror is mounted, a connector for connecting the circuit board and the control means, and a housing member in which these components are incorporated; Have
The laser diode and collimator lens are mounted directly on the housing member,
The housing member is
On the extension line connecting the laser diode and the collimator lens, there is an opening for connecting the connector to the circuit board,
The collimator lens causes the laser diode to emit light before the polygon mirror is incorporated into the housing member, and allows the laser beam transmitted through the collimator lens to pass through the opening to the outside of the housing member. By measuring the laser beam, the position in the optical axis direction is fine-tuned,
Thereby, the position of the collimator lens can be easily adjusted.

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