JP5605257B2 - Laser scanning optical apparatus and image forming apparatus - Google Patents

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, for example, as disclosed in Japanese Patent Application Laid-Open No. 2007-178511 (Patent Document 1), a polygon mirror arranged inside a housing is covered with a cover. Yes. Further, the cover is provided with a heat radiating hole at a portion where the bearing portion of the polygon motor faces, and heat is radiated from the bearing portion of the polygon motor through the heat radiating hole.

JP 2007-178511 A

  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, 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.

  In the laser scanning optical device disclosed in Patent Document 1 described above, the heat generated in the bearing portion of the polygon motor is radiated to the outside through the heat radiation hole. However, heat is generated not only in the bearing portion of the polygon motor but also in the coil and the driving semiconductor element portion. However, no measures against heat dissipation are taken for the coil and the driving semiconductor element portion.

  In a laser scanning optical device of a type (substrate integrated type) in which a driving semiconductor element portion and a polygon motor are formed on the same substrate, two of the coil of the polygon motor and the semiconductor element portion are the heat source on the same substrate. It becomes. Since the polygon mirror at the top of the coil needs to be dustproof, it is necessary to cover the polygon motor with a cover. For this reason, the semiconductor element portion that is not required to be dust-proof disposed on the same substrate is also covered with the cover, and the heat dissipation efficiency of the semiconductor element portion is reduced.

  An object of the present invention is to prevent a change in the beam irradiation position on the photosensitive member by increasing the heat radiation efficiency of heat generated inside the laser scanning optical device in the laser scanning optical device and the image forming apparatus, An object of the present invention is to provide a laser scanning optical apparatus and an image forming apparatus that can suppress deterioration in quality of a printed image in the image forming apparatus.

  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 motor that rotationally drives the deflector, a semiconductor element that is disposed on the substrate and controls the rotational driving of the motor, and a housing that dust-proofs and accommodates the deflector. It arrange | positions so that it may expose from a storage housing | casing.

In another embodiment, a heat radiating member is further provided on the outer surface of the housing case.
In another embodiment, the substrate is arranged so that the semiconductor element is located at a position where heat-dissipating air passing through the heat-dissipating member hits.

  In another form, the substrate has a region surrounded by the housing case and a region protruding from the housing case, and the semiconductor element is disposed in a region protruding from the housing case of the substrate. Has been.

  In another form, the motor has a coil formed on the surface of the substrate, and the semiconductor element is disposed on the back surface opposite to the surface of the substrate on which the coil is formed.

  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 device and the image forming apparatus based on the present invention, the heat radiation efficiency of the heat generated inside the laser scanning optical device is increased, thereby preventing the change of the beam irradiation position on the photosensitive member, and Therefore, it is possible to provide a laser scanning optical device and an image forming apparatus that can suppress quality degradation of a printed image in the image forming apparatus.

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 sectional drawing which shows the accommodation state of the board | substrate in the polygon mirror accommodation housing | casing in a reference technique. FIG. 3 is a cross-sectional view showing a substrate accommodation state in the polygon mirror housing case according to the first embodiment. 6 is a cross-sectional view showing another accommodation state of a substrate in the polygon mirror housing case in Embodiment 1. FIG. FIG. 10 is a cross-sectional view showing a substrate accommodation state in a polygon mirror housing case according to the second 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.
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.

  As shown in FIG. 2, the polygon mirror 40 is attached to the rotating shaft of a motor 42 fixed to the substrate 41. The coil 42 c of the motor 42 is formed on the substrate 41. The substrate 41 is also provided with a driving semiconductor element. 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.

  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.

  Here, with reference to FIG. 5, a heat dissipation structure on the substrate 41 will be described as a reference technique. FIG. 5 is a cross-sectional view showing the accommodation state of the substrate in the polygon mirror housing case according to the reference technique, and corresponds to the cross-section taken along the line VV in FIG. A motor 42 for driving the polygon mirror 40 is disposed on the substrate 41. On the substrate 41, the coil 42c of the motor 42 is directly arranged. A driving semiconductor element 60 is disposed on the same substrate 41.

  The heat radiated from the motor bearing portion 42j, the coil 42c, and the semiconductor element 60 serving as a heat generation source is transferred to the heat dissipating fins 43 also serving as a polygon cover, which are provided on the upper portion of the polygon mirror housing 27A. An air flow (AF) from a heat dissipating fan provided outside is blown to the heat dissipating fins 43 to promote heat dissipation.

  However, since the distance between the semiconductor element 60 and the radiating fin 43 is larger than that of the motor 42, nothing is arranged between the semiconductor element 60 and the radiating fin 43, and the polygon mirror housing 27 </ b> A. It is in a state where heat is easily trapped inside.

(Embodiment 1: See FIGS. 6 and 7)
The laser scanning optical apparatus according to the first embodiment based on the present invention will be described below with reference to FIGS. FIG. 6 is a cross-sectional view showing the accommodation state of the substrate in the polygon mirror housing case, and FIG. 7 is a cross-sectional view showing another accommodation state of the substrate in the polygon mirror housing case. 6 and 7 both correspond to the cross-section taken along the line VV in FIG. In addition, about the same or an equivalent part as a reference technique, the same reference number is attached | subjected and the overlapping description may not be repeated.

  The present embodiment is characterized by the accommodation state of the substrate 41 in the polygon mirror housing 27A, and the semiconductor element 60 is disposed so as to be exposed from the polygon mirror housing 27A. Specifically, the substrate 41 includes a region 41A in which the motor 42 is disposed and surrounded by the polygon mirror housing 27A, and a region 41B protruding from the polygon mirror housing 27A. The semiconductor element 60 includes the substrate 41. Is disposed in a region 41B protruding from the polygon mirror housing 27A.

  The polygon mirror housing 27A needs to be highly confidential so that dust does not adhere to the polygon mirror 40. Therefore, the gap generated between the substrate 41 protruding from the polygon mirror housing 27A and the polygon mirror housing 27A is more airtight than a seal member (not shown).

  Furthermore, the substrate 41 in the present embodiment is bent so that the region 41B of the substrate 41 on which the semiconductor element 60 is disposed is located above the region 41A of the substrate 41 on which the polygon mirror 40 is disposed. ing. Specifically, the region 41B of the substrate 41 is bent so that the region 41B of the substrate 41 is positioned above the upper surface of the polygon mirror housing 27A. As a result, the semiconductor element 60 is disposed at a position where the heat radiation air AF passing through the heat radiation fins 43 hits. As a result, it is possible to efficiently dissipate heat from both the heat radiation fins 43 and the semiconductor element 60 through one air passage.

  As described above, according to the laser scanning optical device 20 and the color printer 1 employing the laser scanning optical device 20 in the above-described embodiment, the semiconductor element 60 is disposed at a position exposed from the polygon mirror housing 27A. Therefore, heat can be effectively radiated as compared with the case where the semiconductor element 60 is covered with the casing.

  Further, a step is provided on the substrate 41 so that the position of the radiation fin 43 that promotes heat radiation from the motor 42 (mainly the coil 42c and the bearing portion) and the height position of the semiconductor element 60 are substantially matched. Thereby, it is possible to effectively dissipate heat with one air flow (AF).

  Further, since the motor 42 and the semiconductor element 60 are spatially separated and the volume of the polygon mirror housing 27A can be reduced, the efficiency of heat transfer to the radiating fins 43 is increased and heat radiation is facilitated. be able to.

  As a result, the heat radiation efficiency of the heat generated inside the laser scanning optical device 20 is increased, the change of the beam irradiation position on the photoconductor is prevented, and the quality deterioration of the printed image in the color printer can be suppressed. .

  When the semiconductor element 60 is exposed from the polygon mirror housing 27A, the semiconductor element 60 is disposed in the region 41B protruding from the polygon mirror housing 27A, so that sufficient heat dissipation of the semiconductor element 60 can be secured. In addition, as shown in FIG. 7, the substrate 41 can be projected from the polygon mirror housing 27A in a flat state without being bent.

(Embodiment 2: Refer to FIG. 8)
A laser scanning optical apparatus according to Embodiment 2 based on the present invention will be described below with reference to FIG. FIG. 8 is a cross-sectional view showing the accommodation state of the substrate in the polygon mirror housing, and corresponds to the cross section taken along the line VV in FIG.

  In the above embodiment, the semiconductor element 60 is disposed in the region 41B protruding from the polygon mirror housing 27A of the substrate 41. However, in this embodiment, the substrate 41 is disposed in the polygon mirror housing 27A. The semiconductor element 60 is exposed from an opening 27 h provided in the polygon mirror housing 27 </ b> A.

  Specifically, the substrate 41 has a region 41A where the motor 42 is disposed and a region 41C where the semiconductor element 60 is disposed. In the region 41A, the coil 42c of the motor 42 is formed on the surface of the substrate 41, and the semiconductor element 60 is disposed on the back surface opposite to the surface of the substrate 41 on which the coil 42c is formed. Furthermore, the region 41C is bent toward the back surface side when viewed from the region 41A, and the region 41C is disposed so as to close the opening 27h.

  Thereby, the semiconductor element 60 is in a state where the polygon mirror housing 27A is exposed, and heat dissipation of the semiconductor element 60 can be promoted. Further, if necessary, in order to further promote the heat dissipation of the semiconductor element 60, the semiconductor element 60 may be exposed to heat release air. The heat radiation air may be the same as the heat radiation air AF that passes through the heat radiation fins 43, or may be a separate air flow dedicated to the semiconductor element 60.

  As described above, also in the laser scanning optical device 20 in the present embodiment and the color printer 1 employing the laser scanning optical device 20, the semiconductor element 60 is removed from the polygon mirror housing 27A as in the first embodiment. Since the semiconductor element 60 is disposed at the exposed position, heat can be radiated more effectively than when the semiconductor element 60 is covered with the housing.

  In addition, since the region 41C of the substrate 41 is disposed so as to close the opening 27h, it is possible to effectively dissipate the semiconductor element 60 while easily maintaining the airtightness of the polygon mirror housing 27A. Become.

  As a result, the heat radiation efficiency of the heat generated inside the laser scanning optical device 20 is increased, the change of the beam irradiation position on the photoconductor is prevented, and the quality deterioration of the printed image in the color printer can be suppressed. .

  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, 13th 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, 27B Optical system Housing case, 27h opening, 31 first imaging 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, 41A , 41B, 41C region, 42 motor, 42c coil, 42j motor bearing portion, 43 heat radiation fin, 45 partial magnification adjustment mechanism, 50 skew adjustment mechanism, 51 stepping motor, 59 bracket, 60 semiconductor element.

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 motor for rotationally driving the deflector;
A semiconductor element disposed on the substrate and controlling rotation of the motor;
A housing case for dust-proofing and housing the deflector,
The semiconductor element is disposed so as to be exposed from the housing .
A heat dissipation member is further provided on the outer surface of the housing,
A laser scanning optical device , wherein the substrate is arranged so that the semiconductor element is located at a position where heat-radiating air passing through the heat-dissipating member hits . The substrate has a region surrounded by the housing case and a region protruding from the housing case,
The laser scanning optical apparatus according to claim 1, wherein the semiconductor element is disposed in a region of the substrate that protrudes from the housing case. The motor has a coil portion formed on the surface of the substrate,
The laser scanning optical device according to claim 1, wherein the semiconductor element is disposed on a back surface opposite to a surface of the substrate on which the coil portion is formed. Claims 1 having a laser scanning optical apparatus according to any one of claims 3, an image forming apparatus.

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