JP2012168467A - Laser scanning optical device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser scanning optical device that has a structure capable of discharging heat generated in the vicinity of a deflector, and an image forming apparatus.SOLUTION: A laser scanning optical device comprises: a polygon mirror 40; a substrate 41 on which the polygon mirror 40 is disposed; a holding member 27 on which the substrate 41 is mounted; and a heat discharging member 60 arranged on an opposite side of the substrate 41 with the holding member 27 interposed therebetween. The heat discharging member 60 penetrates the holding member 27 and the substrate 41, and includes a rectifying plate 63 that surrounds a part of the periphery of the polygon mirror 40.

Description

  The present invention relates to a laser scanning optical apparatus and an image forming apparatus.

  In the field of conventional laser scanning optical devices, it is known that heat generated by rotation of a polygon mirror is generated from a driving semiconductor element and a shaft (bearing portion) associated with the polygon mirror. For example, in the laser scanning optical device disclosed in Japanese Patent Application Laid-Open No. 2008-139349 (Patent Document 1), in order to dissipate this heat, a heat dissipating member is added to the back side of the polygon mirror driving substrate to dissipate heat. The structure which promotes is adopted.

  Japanese Patent Laying-Open No. 2006-153898 (Patent Document 2) discloses a rectifying plate for arranging a semicircular member surrounding the polygon mirror on the outer periphery of the polygon mirror, and for adjusting the wind caused by the rotation of the polygon mirror. The structure which provides is disclosed.

JP 2008-139349 A Japanese Patent Laid-Open No. 2006-153989

  In recent years, printing speeds have been increasing in image forming apparatuses such as laser printers and digital copying machines. In order to cope with this increase in speed, in the laser scanning optical device, a polygon mirror for deflecting and scanning the laser is rotated at a high speed.

  When the polygon mirror is rotated at a high speed, the amount of heat generated in the bearing portion and coil of the polygon motor and the driving semiconductor element portion of the polygon motor increases accordingly, and the temperature in the laser scanning optical device rises. As a result, there is a concern that thermal deformation of the scanning optical element or the like occurs, the beam irradiation position on the photoconductor changes, and the quality of the printed image in the image forming apparatus deteriorates. In particular, the optical element is formed of resin or glass, but a resin lens is easily affected by heat.

  In particular, recently, in order to obtain high image quality, the resolution is increased and a high scanning density such as 1200 dpi is required, and it is necessary to maintain the beam irradiation position with high accuracy. For this reason, it is important to maintain the desired beam irradiation position by suppressing the temperature rise in the laser scanning optical apparatus.

  As a method for avoiding the temperature rise, there are a method for preventing the generation of heat itself by improving the efficiency during rotation of the polygon motor, and a method for actively cooling the heat generating portion. However, in the case of a method for preventing the generation of heat itself, it is necessary to greatly change the configuration of the polygon motor itself, which may increase the cost. Further, in the case of a method of actively cooling the heat generating portion, a method such as installing a heat pipe is conceivable, but this can also be a factor of cost increase.

  An object of the present invention is to provide a laser scanning optical apparatus and an image forming apparatus having a structure capable of efficiently releasing heat generated in the vicinity of a deflector.

  The laser scanning optical device according to the present invention is a laser scanning optical device that forms an image of the laser beam deflected by the deflector on the photosensitive member, the deflector, and a substrate on which the deflector is disposed, A holding member that holds the substrate, and a heat radiating member that is disposed on the opposite side of the substrate across the holding member, the heat radiating member penetrating the holding member and the substrate, and the deflection A baffle plate surrounding a part of the periphery of the vessel.

  In another form, the heat dissipation member includes a holding base positioned on the opposite side of the substrate across the holding member, the rectifying plate provided on the deflector side of the holding base, and the holding base. A heat dissipating member provided on the opposite side of the current plate.

  In another form, the heat radiating member has a shape that is symmetrical to the current plate across the holding base.

  An image forming apparatus based on the present invention includes any one of the above-described laser scanning optical devices.

  According to the laser scanning optical apparatus and the image forming apparatus based on the present invention, there are provided a laser scanning optical apparatus and an image forming apparatus having a structure capable of efficiently releasing the heat generated in the vicinity of the deflector. Is possible.

It is a schematic block diagram which shows the color printer provided with the laser scanning optical apparatus in this Embodiment. It is sectional drawing of a laser scanning optical apparatus. It is a top view of a laser scanning optical apparatus. It is a bottom view of a laser scanning optical apparatus. It is a fragmentary perspective view which shows the structure around the polygon mirror in embodiment. It is a perspective view which shows the structure of the heat radiating member in embodiment. It is a partial disassembled perspective view which shows the structure around the polygon mirror in embodiment. FIG. 6 is a cross-sectional view taken along line VIII-VIII in FIG. 5. It is a perspective view which shows the structure of the heat radiating member in other embodiment.

  The laser scanning optical apparatus and the image forming apparatus in each embodiment based on the present invention will be described below with reference to the drawings. Note that in the embodiments described below, when referring to the number, amount, and the like, the scope of the present invention is not necessarily limited to the number, amount, and the like unless otherwise specified. The same parts and corresponding parts are denoted by the same reference numerals, and redundant description may not be repeated. In addition, it is planned from the beginning to use the structures in the embodiments in appropriate combinations.

  In the following, a color printer adopting a general full-color electrophotographic system is described as an example of an image forming apparatus, but the present invention is not limited to the full-color electrophotographic system. Also, it can be applied to a printer that employs one type of laser scanning optical device (such as black) that forms only a monochrome image. In addition to a printer, a laser scanning optical device according to the present invention can be mounted on an image forming apparatus such as a copying machine or a FAX.

(See the overall configuration of the color printer 1, FIG. 1)
FIG. 1 shows a schematic configuration of a color printer 1 equipped with a laser scanning optical device 20 according to the present invention. The color printer 1 is configured to synthesize four color images in a tandem manner.

  An intermediate transfer belt 10 is disposed immediately above the four image forming stations 2 (2Y, 2M, 2C, 2K), and a laser scanning optical device 20 is disposed immediately below. Each image forming station 2 is provided with a photosensitive drum 3 (3Y, 3M, 3C, 3K), a developing device 4 (4Y, 4M, 4C, 4K), a charger (not shown), a residual toner cleaner, and the like. ing. Note that the image forming station 2K for forming a black image is configured in a large size so that a frequently used monochrome image can be formed at high speed.

  The laser scanning optical device 20 forms an image (electrostatic latent image) on each photosensitive drum 3 by the light beams By, Bm, Bc, and Bk emitted based on the Y, M, C, and K image data. This latent image is visualized with toner.

  The intermediate transfer belt 10 is stretched endlessly around the drive roller 11 and the support roller 12. On the intermediate transfer belt 10, the toner images of the respective colors formed on the respective photosensitive drums 3 based on the rotation in the arrow Y direction are sequentially primary-transferred and synthesized.

  The recording paper P is stored in the automatic paper cassette 5 and is fed one by one at a predetermined timing. The synthetic toner image is secondarily transferred onto the recording paper P from the intermediate transfer belt 10 at the secondary transfer position 13 via the paper passing path 6. The recording paper P that has been secondarily transferred is subjected to heat fixing of the toner by the fixing device 15 and then discharged from the discharge roller 16 onto the paper discharge unit 9.

  When performing double-sided printing on the recording paper P, the recording paper P is conveyed from the switchback roller 17 to the outside of the color printer 1, switched back, and returned to the secondary transfer position 13 via the reverse path 7. It is. Here, the recording paper P on which the toner image is secondarily transferred on the back surface is discharged from the discharge roller 16 onto the paper discharge unit 9.

(Schematic configuration of the laser scanning optical device 20, see FIGS. 2 to 4)
2 is a cross-sectional view of the laser scanning optical device 20, FIG. 3 is a plan view, and FIG. 4 is a bottom view. The laser scanning optical device 20 includes a light source unit 21, a polygon mirror 40, first and second imaging lenses 31, 32 as an example of a deflector, folding mirrors 34, 35, 36 provided for each optical path, and first mirrors. It has the 3 imaging lens 33 and the housing | casing 27 holding these members. The housing 27 houses a polygon mirror housing housing 27A that protects the polygon mirror 40, the first and second imaging lenses 31, 32, the folding mirrors 34, 35, 36, the third imaging lens 33, and the like. And an optical system housing 27B.

  The light source unit 21 includes a laser diode 22 (22Y, 22M, 22C, 22K), a composite mirror 23 (23Y, 23M, 23C), a folding mirror 24, and a cylindrical lens 25, and is mounted on a plate 26. Yes.

  The light beam emitted from the laser diode 22K is guided to the folding mirror 24. Further, the light beams emitted from the laser diodes 22C, 22M, and 22Y are reflected by the combining mirrors 23C, 23M, and 23Y, respectively, and guided to the folding mirror 24. Each light beam reflected by the folding mirror 24 is condensed in the sub-scanning direction Z (see FIG. 2) by the cylindrical lens 25 and guided to the same surface of the polygon mirror 40 with a predetermined angle in the sub-scanning direction Z.

  These light beams are deflected at a constant angular velocity in the main scanning direction X (see FIG. 3) based on the rotation of the polygon mirror 40, and pass through the first and second imaging lenses 31 and 32. The light beam Bk passes through the third imaging lens 33K, is reflected by the folding mirror 34K, and exposes and scans on the photosensitive drum 3K. The light beam Bc is reflected by the folding mirrors 34C and 35C, passes through the third imaging lens 33C, is further reflected by the folding mirror 36C, and exposes and scans the photosensitive drum 3C.

  The light beam Bm is reflected by the folding mirror 34M, passes through the third imaging lens 33M, is further reflected by the folding mirror 35M, and exposes and scans the photosensitive drum 3M. The light beam By is reflected by the folding mirror 34Y, passes through the third imaging lens 33Y, is further reflected by the folding mirror 35Y, and exposes and scans the photosensitive drum 3Y.

  In order to detect the writing position of each scanning line on each photosensitive drum 3, that is, to obtain a main scanning synchronization signal, the upstream side beam in the main scanning direction of the beam Bk deflected by the polygon mirror 40 is shown in FIG. As shown, the light is reflected by the detection mirror 37, condensed by the lens 38, and enters the sync signal detection light receiving sensor 39.

  The casing 27 is fixed to a frame (not shown) of the color printer 1 by, for example, screwing at three fixing points Z1, Z2, and Z3 (see FIG. 3).

  Further, as shown in FIG. 3, a partial magnification adjustment mechanism 45 and a skew adjustment mechanism 50 are installed as color misregistration adjustment (registration adjustment). The skew adjustment mechanism 50 includes a stepping motor 51 fixed to the casing 27 via a bracket 59 as a drive source. Detailed descriptions of the partial magnification adjustment mechanism 45 and the skew adjustment mechanism 50 are omitted.

(Refer to the structure around the polygon mirror 40, FIG. 2, FIG. 5 to FIG. 8)
Next, the structure around the polygon mirror 40 will be described with reference to FIGS. 2 and 5 to 8. 5 is a partial perspective view showing the structure around the polygon mirror 40, FIG. 6 is a perspective view showing the structure of the heat dissipation member 60, FIG. 7 is a partially exploded perspective view showing the structure around the polygon mirror, and FIG. These are sectional views taken along line VIII-VIII in FIG. 5 to 8 are shown upside down with respect to FIG. 2 in order to facilitate understanding of the structure.

  First, referring to FIG. 2, the polygon mirror 40 is attached to a rotating shaft of a motor 42 fixed to a substrate 41. The coil 42 c of the motor 42 is formed on the substrate 41. A driving semiconductor element (not shown) is also disposed on the substrate 41. A heat radiating fin 43 is attached to the upper position of the motor 42 of the polygon mirror housing 27A as an example of a heat radiating member.

  With reference to FIGS. 5 and 6, a heat radiating member 60 is disposed on the opposite side of the substrate 41 with the holding portion 27 </ b> A <b> 1 constituted by the upper wall of the polygon mirror housing 27 </ b> A interposed therebetween. As shown in FIG. 6, the heat radiating member 60 is provided on the opposite side of the rectangular holding base 61, the rectifying plate 63 provided on the polygon mirror side of the holding base 61, and the rectifying plate 63 of the holding base 61. The heat dissipating fins 62 are provided. The heat radiating member 60 is made of a material excellent in heat conduction, such as aluminum die casting.

  The rectifying plate 63 has a semi-cylindrical shape and has a form surrounding a part of the periphery of the polygon mirror 40. As shown in FIG. 4, the rectifying plate 63 is opened on the side of the polygon mirror 40 facing the first imaging lens 31 and the second imaging lens 32, and the first imaging lens 31 and the second connection of the polygon mirror 40 are opened. A rectifying plate 63 is provided on the side opposite to the image lens 32.

  Referring again to FIG. 6, the heat dissipating fins 62 have a form extending along the longitudinal direction of the rectangular holding base 61, and a plurality of heat dissipating fins 62 are provided at a predetermined interval. In the present embodiment, the holding base 61, the plurality of radiating fins 62, and the rectifying plate 63 are integrally formed.

  Referring to FIG. 7, the holding portion 27 </ b> A <b> 1 is provided with an arc-shaped through hole 27 h that penetrates the rectifying plate 63. Similarly, the substrate 41 is also provided with an arc-shaped through hole 41 h that penetrates the rectifying plate 63. ing.

  In the state where the substrate 41 and the heat dissipation member 60 are assembled to the holding portion 27A1, the rectifying plate 63 of the heat dissipation member 60 penetrates the through hole 27h of the holding portion 27A1 and the through hole 41h of the substrate 41 as shown in FIG. Then, a part of the periphery of the polygon mirror 40 is surrounded by the current plate 63.

  With reference to FIG. 8, the heat radiating member 60 has the heat radiating fins 62 and the rectifying plates 63, so that the heat generated in the vicinity of the polygon mirror 40 is directly transmitted to the radiating fins 62 through the rectifying plates 63. It will be. The radiating fins 62 are cooled by air flowing into the radiating fins 62 using a blower fan (not shown). As a result, heat generated in the vicinity of the polygon mirror 40 is absorbed by the rectifying plate 63, and the heat can be efficiently transmitted to the radiation fins 62 and can be efficiently radiated using the radiation fins 62.

  In addition, 60 A of heat radiating members shown in FIG. 9 are mentioned as another form of the heat radiating member 60. FIG. The basic shape of the heat dissipating member 60A is the same as that of the heat dissipating member 60 shown in FIG. 6, but further, the heat dissipating fins 63a having the same shape as the current plate 63 are located at positions symmetrical to the current plate 63 with the holding base 61 interposed therebetween. Is provided. Thereby, the heat absorbed by the rectifying plate 63 is directly transmitted to the heat radiating fins 63a, and it becomes possible to promote heat dissipation more effectively.

  In each of the above embodiments, the case where the polygon mirror 40 is used as an example of the deflector has been described. However, a resonant scanner, a galvanometer mirror, or the like may be used instead of the polygon mirror 40.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 color printer, 2, 2K image forming station, 3, 3C, 3K, 3M, 3Y photosensitive drum, 4 developing unit, 5 automatic paper feed cassette, 6 paper feed path, 7 reversing path, 9 paper discharge unit, 10 intermediate Transfer belt, 11 drive roller, 12 support roller, 13 secondary transfer position, 15 fixing device, 16 discharge roller, 17 switchback roller, 20 laser scanning optical device, 21 light source unit, 22, 22C, 22M, 22Y, 22K laser Diode, 23, 23C, 23M, 23Y Composite mirror, 24, 34, 35, 36, 34C, 35C, 34M, 34Y Folding mirror, 25 Cylindrical lens, 26 plate, 27 housing, 27A Polygon mirror housing housing, 27A1 holding Part, 27B optical system housing, 27h, 41h through hole, 31 1st Image lens, 32 second imaging lens, 33, 33C, 33K, 33M, 33Y third imaging lens, 34K, 35M, 35Y, 36C mirror, 37 detection mirror, 38 lens, 39 sync signal detection light receiving sensor, 40 polygon mirror, 41 substrate, 42 motor, 42c coil, 43 heat radiation fin, 45 partial magnification adjustment mechanism, 50 skew adjustment mechanism, 51 stepping motor, 59 bracket, 60, 60A heat radiation member, 61 holding base, 62 heat radiation fin, 63 Rectification plate, 63a heat radiation fin, 63a direct heat radiation fin.

Claims (4)

A laser scanning optical device for imaging a laser beam deflected by a deflector on a photosensitive member,
The deflector;
A substrate on which the deflector is disposed;
A holding member for holding the substrate;
A heat dissipating member disposed on the opposite side of the substrate across the holding member,
The laser scanning optical device, wherein the heat radiating member includes a rectifying plate that penetrates the holding member and the substrate and surrounds a part of the periphery of the deflector. The heat dissipation member is
A holding base located on the opposite side of the substrate across the holding member;
The rectifying plate provided on the deflector side of the holding base;
The laser scanning optical apparatus according to claim 1, further comprising a heat radiating member provided on a side of the holding base opposite to the rectifying plate.   The laser scanning optical device according to claim 2, wherein the heat radiating member has a shape that is symmetrical to the current plate with the holding base interposed therebetween.   An image forming apparatus comprising the laser scanning optical device according to claim 1.

Images