JP6047073B2 - Optical scanning apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an optical scanning device and an image forming apparatus including the same.

  In general, in an image forming apparatus such as a printer or a copying machine, an optical scanning device is used to expose an image carrier such as a photosensitive drum. In recent years, since full-color printers and copiers have increased the speed of forming color images, tandem full-color machines equipped with photosensitive drums corresponding to four colors (cyan, magenta, yellow, and black) are generally used. It has become.

  As an optical scanning device used in such an image forming apparatus, a laser beam for four colors is incident on one deflector (polygon motor, etc.), and then the optical path is separated to laser the photosensitive drum of each color. A configuration for guiding each beam is known.

  On the other hand, since the allowable number of revolutions of the polygon motor is limited, it is possible to further increase the speed of image formation and the resolution of the formed image only by making one laser beam incident on the photosensitive drum from one light source unit. It is difficult. In view of this, a multi-beam type optical scanning device has been developed in which a plurality of laser beams are simultaneously incident on a photosensitive drum from a single light source (see, for example, Patent Document 1).

  In Patent Document 1, a laser diode having a plurality of light emitting points arranged in an array (hereinafter referred to as a laser diode array) is mounted on one end side of a cylindrical portion, while a collimator lens is provided on the other end side of the cylindrical portion. It is disclosed that the mounted light source unit is fitted into a circular hole formed in a side wall of a housing of the optical scanning device. In the light source unit, the laser diode array can also be rotated around the optical axis by rotating the cylindrical portion around the optical axis of the collimator lens. As a result, the intervals in the sub-scanning direction (hereinafter also referred to as inter-beam distances) of the plurality of laser beams incident on the photosensitive drum are adjusted. After the distance between the beams is adjusted, the cylindrical portion is fixed to the side wall of the housing with screws.

JP 2000-98285 A

  Therefore, in an optical scanning device in which laser beams are incident on one deflector from a plurality of light source units, it is conceivable that each light source unit has a laser diode array.

  However, the laser diode array needs to be mounted on a substrate member. If a plurality of laser diode arrays are mounted on one substrate member, each laser diode array must be individually rotated with respect to the substrate in order to adjust the inter-beam distance. There is a possibility that an unreasonable force is applied to the terminals of the laser diode array that is connected, resulting in poor connection between the laser diode array and the substrate member.

  On the other hand, it is conceivable to individually mount the laser diode array on a plurality of substrate members. However, since the substrate member is relatively large, a space is required so that the substrate member can rotate with the laser diode array when adjusting the inter-beam distance. Therefore, it is difficult to arrange a plurality of laser diode arrays close to each other in a limited space.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a laser diode array for an optical scanning device that allows a laser beam to be incident on one deflector from a plurality of light source units having a laser diode array. It is to arrange each light source part suitably in the limited space, suppressing the connection failure with the board member.

An optical scanning device according to the present invention includes four light source units, a deflector into which light emitted from each of the four light source units is incident, and a side wall on which a step portion is formed. The four light source sections emit light in parallel to each other outside the side wall, and are arranged in a step shape with respect to the light emitting direction and supported by the step section. The four light source sections have a plurality of light emitting sections and are rotatably supported with respect to the stepped section of the casing, and a substrate member in which the laser diode arrays are mounted and integrated In the substrate member, the positions of the connectors electrically connected to the terminals of the laser diode array are shifted from each other in the direction orthogonal to the light emission direction .

  According to this configuration, each of the plurality of light source units has a laser diode array, and each of the plurality of laser beams emitted from the laser diode array of each light source unit enters the deflector. Therefore, it is possible to perform optical scanning at high speed and with a large number of laser beams while suppressing the number of deflectors to one.

  In addition, since the laser diode array is individually mounted on a plurality of substrate members and is rotatably supported with respect to the housing, the laser diode array is mounted on the substrate on which the laser diode array is mounted. It can be rotated with the member. Therefore, since the laser diode array can be rotated integrally with the substrate member without rotating the laser diode array with respect to the substrate member, poor connection between the laser diode array and the substrate member can be suppressed.

  In addition, since the plurality of light source portions are arranged in steps with respect to the light emission direction, adjacent substrate members can be arranged so as to overlap each other. Therefore, since each board member can be rotated without interfering with each other, each light source section can be suitably arranged in a limited space.

  The step length of the casing in which the light source unit is disposed is preferably the same as the interval between laser beams emitted from the laser diode arrays of the adjacent light source units.

  According to this configuration, it is possible to make the optical path length from the laser diode array to the deflector of each light source unit the same by arranging each light source unit in a step shape having the same length as the interval between the laser beams. Become. As a result, it is possible to suppress variations in the optical characteristics of the laser beam incident on the deflector from each light source unit.

  An image forming apparatus according to the present invention includes the optical scanning device.

  According to the present invention, in an optical scanning device that allows a laser beam to be incident on one deflector from a plurality of light source units having a laser diode array, each light source unit is controlled while suppressing poor connection between the laser diode array and the substrate member. It can be suitably arranged in a limited space.

FIG. 1 is a cross-sectional view illustrating a schematic structure of an image forming apparatus according to the present embodiment. FIG. 2 is an enlarged plan view partially showing the inside of the optical scanning device. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a front view showing the board member attached and fixed to the housing. 5 is a cross-sectional view taken along line VV in FIG. FIG. 6 is an enlarged front view showing a light emitting portion of the laser diode array. FIG. 7 is an enlarged sectional view showing a structure for attaching the light source unit to the housing.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiment.
<Image forming apparatus>

  FIG. 1 is a cross-sectional view illustrating a schematic structure of the image forming apparatus 1. The image forming apparatus 1 is, for example, a tandem color printer. As shown in FIG. 1, the intermediate transfer belt 7, the primary transfer unit 8 and the secondary transfer unit 9, a fixing device 11, and an optical scanning device 15. And a plurality of image forming units 16.

  A paper feed cassette 3 is disposed below the inside of the main body 2 of the image forming apparatus 1. The paper feed cassette 3 stores and accommodates sheets (not shown) such as paper before printing. A first paper transport unit 21 is provided on the side of the paper feed cassette 3. The first paper transport unit 21 receives the paper fed from the paper feed cassette 3 and transports the paper to the upper secondary transfer unit 9.

  A manual paper feed unit 5 is provided on the right side of the paper feed cassette 3. A second paper transport unit 22 is provided on the left side of the manual paper feed unit 5. The second paper transport unit 22 receives the paper sent from the manual paper feed unit 5 and transports it to the first paper transport unit 21.

  The optical scanning device 15 is disposed above the second paper transport unit 22 and irradiates the image forming unit 16 with laser light based on the image data received by the image forming device 1. For example, four image forming units 16 are provided above the optical scanning device 15. An endless intermediate transfer belt 7 is provided above each image forming unit 16. The intermediate transfer belt 7 is wound around a plurality of rollers and is rotationally driven by a driving device (not shown).

  As shown in FIG. 1, the four image forming units 16 are arranged in a line along the intermediate transfer belt 7, and respectively form yellow, magenta, cyan, or black toner images. That is, in each image forming unit 16, an electrostatic latent image of the original image is formed on the photosensitive drum 25 by the laser light irradiated by the optical scanning device 15, and each color toner is developed by developing the electrostatic latent image. An image is formed.

  The primary transfer unit 8 is disposed above each image forming unit 16. The primary transfer unit 8 includes a transfer roller that primarily transfers the toner image formed by the image forming unit 16 to the surface of the intermediate transfer belt 7.

  Then, the intermediate transfer belt 7 is driven to rotate, and the toner image of each image forming unit 16 is transferred to the intermediate transfer belt 7 at a predetermined timing, so that the surface of the intermediate transfer belt 7 has yellow, magenta, A color toner image in which toner images of four colors of cyan and black are superimposed on each other is formed.

  As shown in FIG. 1, the secondary transfer unit 9 has a transfer roller 17 disposed on the left side of the intermediate transfer belt 7. The secondary transfer unit 9 applies a transfer bias voltage having a polarity opposite to that of the toner to the sheet sent from the first sheet transport unit 21 so as to transfer the toner image from the intermediate transfer belt 7 to the sheet. It has become.

  The fixing device 11 is provided above the secondary transfer unit 9. Between the secondary transfer unit 9 and the fixing device 11, a third paper transport unit 23 that transports the paper on which the toner image has been secondarily transferred to the fixing device 11 is formed. The fixing device 11 includes a pressure roller 18, a fixing roller 19, and a heating roller 20. The fixing device 11 heats and pressurizes the sheet conveyed from the third sheet conveying unit 23 to fix the toner image on the sheet.

A branch portion 27 is provided above the fixing device 11. The sheet discharged from the fixing device 11 is discharged from the branching unit 27 to the sheet discharging unit 28 formed on the upper portion of the image forming apparatus 1 when double-sided printing is not performed. When performing duplex printing, the paper is conveyed again from the branching unit 27 to the secondary transfer unit 9 via the fourth paper conveying unit 24.
<Optical scanning device>

  FIG. 2 partially shows the inside of the optical scanning device 15 in an enlarged manner. 3 shows a cross section taken along line III-III in FIG. 2, and FIG. 5 shows a cross section taken along line V-V in FIG. FIG. 4 shows a substrate member 39 that is fixedly attached to the housing 31. FIG. 6 shows an enlarged view of the light emitting portion 41 of the laser diode array 38. FIG. 7 shows the attachment structure of the light source unit 32 to the housing 31 in an enlarged manner.

  As shown in FIG. 2, the optical scanning device 15 includes a plurality of light source units 32, a polygon mirror 35 as a deflector into which light emitted from each of the plurality of light source units 32 is incident, and a box that houses the polygon mirror 35. The case 31 is provided. 2 shows a state in which a lid member (not shown) that closes the casing 31 is removed.

  The casing 31 is formed of, for example, a resin material whose strength is increased by mixing glass fibers. As shown in FIG. 5, the polygon mirror 35 is provided at the bottom of the casing 31 via a polygon motor 36. The polygon mirror 35 is a rotary polygon mirror and is driven to rotate by a polygon motor 36.

  In addition, an imaging lens (fθ lens) 37 provided in the optical path of the light reflected by the polygon mirror 35 is accommodated in the housing 31. The imaging lens 37 is installed on the bottom of the casing 31 on the side of the polygon mirror 35.

  The plurality of light source parts 32 are fixedly attached to the side part of the casing 31. As shown in FIGS. 2 and 7, the plurality of light source units 32 each have a laser diode array 38 and a substrate member 39 on which the laser diode array 38 is mounted.

  The laser diode array 38 has, for example, a cylindrical outer peripheral surface. A plurality of light emitting portions 41 that emit a laser beam are provided at the tip of the laser diode array 38. As shown in FIG. 6, for example, four light emitting units 41 are provided and arranged so as to be aligned on a straight line.

  On the substrate member 39, wiring (not shown) electrically connected to the terminals 38a of the laser diode array 38 is formed. The board member 39 is provided with a connector 40 electrically connected to the wiring.

  As shown in FIG. 2, a collimator lens 43, an aperture 44, a first mirror 45, a second mirror 46, a third mirror 47, and a cylindrical lens 48 are provided between each light source unit 32 and the polygon mirror 35. Is arranged.

  The collimator lens 43 is a lens for converting a plurality of laser beams emitted from the laser diode array 38 into parallel light. The aperture 44 is for regulating the spread of the laser beam. The cylindrical lens 48 is a lens for condensing the laser beam group and guiding it to the polygon mirror 35.

  2-5, the light source part 32, the collimator lens 43, the aperture 44, and the 1st mirror 45 are arrange | positioned so that the height from the bottom face of the housing | casing 31 may differ for every optical path. ing.

  Thus, the plurality of laser beams emitted from the laser diode array 38 of the light source unit 32 are collimated by the collimator lens 43 and then pass through the aperture 44, whereby the spread of the beams is restricted and the first laser beam is regulated. Reflected by the mirror 45. The laser beam reflected by the first mirror 45 is reflected by the second mirror 46 and the third mirror 47 and enters the cylindrical lens 48. The plurality of laser beams incident on the cylindrical lens 48 are condensed with each other. The condensed laser beam is reflected by the polygon mirror 35 and passes through the imaging lens 37 to form an image on the photosensitive drum 25.

  The scanning light imaged on the surface of the photosensitive drum 25 scans the surface of the photosensitive drum 25 in the main scanning direction by the rotation of the polygon mirror 35, and scans in the sub-scanning direction by the rotation of the photosensitive drum 25. An electrostatic latent image is formed on the surface of the body drum 25.

  In the present embodiment, the plurality of light source units 32 emit light parallel to each other and are arranged in steps with respect to the light emission direction. The laser diode array 38 is supported so as to be rotatable with respect to the housing 31.

  That is, as shown in FIG. 2, the housing 31 has a stepped portion 33 in which a part of the side wall of the housing 31 is formed in a stepped shape. The step portion 33 has a plurality of support surfaces 33a provided in steps. Each support surface 33a of the step portion 33 is provided with a light source support portion 51 for rotatably supporting the laser diode array 38. As a result, the light source unit 32 is supported by the support surface 33 a of the housing 31 via the light source support unit 51.

  As shown in FIG. 7, the light source support 51 is formed in a block shape, and a through hole 52 is formed in the center thereof. The laser diode array 38 is inserted into the through hole 52. The inner peripheral surface of the through hole 52 is formed so as to be inscribed in the cylindrical outer peripheral surface of the laser diode array 38. As a result, the laser diode array 38 can rotate with respect to the light source support 51. The rotational axis of the laser diode array 38 coincides with the optical axis of the collimator lens 43.

  A translucent hole 53 is formed through the side wall of the casing 31 in the step portion 33 at a position concentric with the through hole 52 of the light source support portion 51. The laser beam emitted from the laser diode array 38 enters the collimator lens 43 through the light transmission hole 53.

  As shown in FIG. 2, the step length A of the casing 31 in which the light source unit 32 is arranged is the same in the step unit 33, and the laser beam emitted from the laser diode array 38 of the adjacent light source unit 32. The interval B between them is also the same. In this embodiment, the step length A of the casing 31 is the same as the interval B between the laser beams emitted from the adjacent laser diode arrays 38.

  With the above configuration, when adjusting the interval (inter-beam distance) of the plurality of laser beams incident on the photosensitive drum 25 in the sub-scanning direction, the screws that fix the light source unit 32 to the housing 31 are removed. The laser diode array 38 is rotated around the optical axis of the collimator lens 43. After adjusting the distance between the beams, the light source unit 32 is screwed to the housing 31.

  In the optical scanning device 15 of the present embodiment, first, a laser beam is incident on the polygon mirror 35 from the plurality of light source units 32, and each light source unit 32 includes a laser diode array 38. The optical scanning can be performed at a high speed and with a high number of laser beams while the number of laser beams is limited to one. In addition, since the image forming apparatus 1 includes the optical scanning device 15, an image can be formed at high speed and with high definition.

  Further, since the laser diode array 38 is individually mounted on the plurality of substrate members 39 and is rotatably supported with respect to the casing 31, the laser diode array 38 is mounted on the laser diode array 38. The substrate member 39 can be rotated together. Therefore, since the laser diode array 38 can be rotated integrally with the substrate member 39 without rotating the laser diode array 38 with respect to the substrate member 39, the connection failure between the laser diode array 38 and the substrate member 39 is suppressed. it can.

  In addition, since the plurality of light source sections 32 are arranged in a step shape with respect to the light emitting direction, adjacent substrate members 39 can be arranged so as to overlap each other as shown in FIG. Therefore, since each board | substrate member 39 can be rotated without mutually interfering, each light source part 32 can be arrange | positioned suitably in the limited space.

  In addition, since the step length A of the step portion 33 in which the light source unit 32 is disposed is the same as the interval B between the laser beams emitted from the adjacent laser diode arrays 38, the laser diode of each light source unit 32 The optical path length from the array 38 to the polygon mirror 35 can be made the same. As a result, variations in the optical characteristics of the laser beam incident on the polygon mirror 35 from each light source unit 32 can be suppressed.

  In the above-described embodiment, the color printer is described as an example of the image forming apparatus. However, the present invention is not limited to this. For example, another image forming apparatus including the optical scanning device 15 such as a copying machine, a scanner device, or a multifunction device. It is good.

  As described above, the present invention is useful for an optical scanning device and an image forming apparatus including the same.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 15 Optical scanning device 31 Case 32 Light source part 35 Polygon mirror (deflector)
38 Laser diode array 39 Substrate member 41 Light emitting part A Step length B Space between laser beams

Claims (3)

Four light sources,
A deflector into which light emitted from each of the four light source units is incident;
A side wall having a stepped portion and a housing for accommodating the deflector;
The four light source parts emit light parallel to each other outside the side wall and are arranged in a step shape with respect to the light emitting direction, and are supported by the step part.
The four light source units have a plurality of light emitting units and are supported rotatably with respect to the stepped portion of the housing, and a substrate member on which the laser diode array is mounted and integrated Each with
In the substrate member of the four light source units, the position of the connector electrically connected to the terminal of the laser diode array is shifted from each other in the direction orthogonal to the light emitting direction . The optical scanning device according to claim 1,
The optical scanning device, wherein the step length of the housing in which the light source unit is arranged is the same as the interval between laser beams emitted from the laser diode arrays of the adjacent light source units. An image forming apparatus comprising the optical scanning device according to claim 1.

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