JP2002162591A - Optical writing unit and image forming device equipped therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an optical system and electronic components from being adversely affected due to heat generated from a light source and a circuit board which are for modulating and controlling the light source. SOLUTION: A light-emitting port 20a, through which the light from a light source device 20 is emitted, is arranged in a housing 24, and the housing 24 is kept in a nearly hermetically sealed state, where an LD control board 19 for modulating and controlling a semiconductor laser being the light source according to image data and allowing it to flicker, i.e. emit light strongly or weakly is exposed to the outside of the housing 24. Thus, the temperature inside the housing 24 is prevented from being raised by the heat generated in the control board 19, so as to prevent image nonconformities from occurring due to the temperature of the respective component disposed inside the housing 24 rises, causing deformation or positional fluctuation of each components.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical writing unit for forming an image by deflecting and scanning a light beam emitted from a light source device onto a surface to be scanned, and a copier, a printer, and a copying machine having the same.
The present invention relates to an image forming apparatus such as a facsimile or a multifunction peripheral having both functions.

[0002]

2. Description of the Related Art For example, a conventional electrophotographic image forming apparatus includes an image reading device, an optical writing unit serving as a laser scanning device using a laser beam, and an automatic document feeder (AD).
F). An optical writing unit used in such an image forming apparatus includes, for example, a polygon mirror 5 in a housing (housing) 52 as shown in FIG.
3 and the fθ lens 64 and the like.
2 is closed by a bottom plate or the like of an image reading device or the like located at the top of the mirror 2, and an opening for light transmission formed at the bottom is mirror 5.
5 is completely closed with a dustproof glass (not shown) located below, and the inside of the housing 52 is sealed.

[0005] Each component such as the polygon mirror 53 and the fθ lens 64 in the housing 52 is directly fixed to a predetermined position using a screw or another fixing member. In FIG. 7, reference numeral 50 denotes a photosensitive drum that scans a laser beam in the main scanning direction, 54 denotes a cylindrical lens, and 59 denotes a light source device (semiconductor laser unit) including a semiconductor laser.

In the image forming apparatus, as described above, the image reading device is disposed above the optical writing unit for layout reasons, and the upper surface of the optical writing unit is closed by the bottom plate. (See, for example, Japanese Patent Application Laid-Open No. 10-320018). The optical writing unit will be described with reference to FIG.
4 and the rear side plate 75 are connected via stays 76 and 77,
The optical writing unit 71 is mounted on the stays 76 and 77, and the housing 72 of the optical writing unit 71 is fixed to the stays 76 and 77, respectively. An image reading device 80 is disposed on the optical writing unit 71, and a housing 81 of the image reading device 80 is mounted on the front side plate 74 and the rear side plate 75 by screws. Then, with the image reading device 80 fixed to the upper portion of the optical writing unit 71, the joint between the housing 72 of the optical writing unit 71 and the housing 81 of the image reading device 80 is sealed by a seal member. .

[0005] On the bottom surface of the housing 81 of the image reading device 80,
A plurality of openings are formed as shown by broken lines in FIG.
Their openings are closed by covers 82, 83, 84 and 85, respectively, which cover them.
Each of 3, 84 and 85 is detachable. Then, when the cover 82 is removed, the optical writing unit 71 located thereunder passes through the opening that appears there.
The light source device (semiconductor laser unit) 79 inside can be taken out. The light source device 79 includes a semiconductor laser (LD) mounted on an inverted T-shaped holding member 86 as shown in FIG.
89, a collimating lens 87, an LD control plate 88, and the like.

Similarly, when the cover 83 shown in FIG. 9 is removed, a deflector 93 having a polygon mirror located thereunder can be taken out through an opening that appears there,
The polygon mirror can be cleaned. Further, when the cover 84 is removed, the fθ lens 94 and the synchronization detection sensor (optical sensor) 97 located thereunder can be replaced and cleaned through the opening that appears there. When the cover 85 is removed, the mirror 95 can be replaced. And cleaning becomes possible. The components such as the light source device 79, the deflector 93, and the fθ lens 94 in the housing 72 are fixed to the housing 72 by screws.

[0007]

However, in the case of such an optical writing unit 71, since the light source device 79 is stored in the sealed housing 72, FIG.
The heat generated from the LD control plate 88 and the semiconductor laser 89 shown in (1) is trapped in the housing 72, which causes a problem that the temperature inside the housing 72 rises. When the temperature inside the housing 72 rises in this way, when the optical element such as the collimator lens 87 is made of resin, the position fluctuates due to thermal deformation due to the rise in temperature, In some cases, the image was adversely affected. The present invention has been made in view of the above-mentioned problems, and heat generated from an integrated circuit on a driving circuit board that modulates and controls a light source of a light source device and the light source according to image data is generated by an optical system or an electronic component. The purpose is to not adversely affect the It is another object to improve the interchangeability of the light source device.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a light source device having a light source and modulation control means for modulating the light source in accordance with image data, and light emitted from the light source device. A deflector that deflects the light beam, an imaging lens that forms an image of the light beam deflected and scanned by the deflector on the surface to be scanned, a housing that houses the deflector and the imaging lens, and that the interior of the housing is substantially sealed. An optical writing unit having a cover for closing the light emitting device, wherein a light emission port for emitting light of the light source device is arranged in the housing, and the modulation control means is exposed to the outside of the housing. The housing is kept substantially sealed.

In the above-mentioned optical writing unit, a light source device mounting portion which allows the light source device to be attached and detached in a direction perpendicular to the bottom surface of the housing is formed in the housing, and the light source device is mounted on the light source device mounting portion. It is preferable to keep the inside of the housing in a substantially sealed state by covering the cover in the attached state. In the optical writing unit, the light source device and the light source device may be mounted in a state where the light source device and the light source device mounting portion on the housing side are attached to the light source device. A labyrinth structure having a portion overlapping with the mounting portion in the optical axis direction of the light beam may be provided. And it is effective if the member holding the light source and the modulation control means of the light source device is formed of a material having high thermal conductivity. Further, it is preferable that any one of the above optical writing units is provided to constitute the image forming apparatus.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing an embodiment of an optical writing unit according to the present invention with a cover removed, and FIG. 2 is an exploded perspective view showing a light source device of the optical writing unit and a part of a housing for mounting the same. FIG. 3
FIG. 4 is a perspective view showing a state in which the light source device is attached to a housing. FIG. 4 is an overall configuration diagram showing a digital copying machine which is an image forming apparatus equipped with the optical writing unit of FIG. The digital copying machine which is the image forming apparatus shown in FIG.
An image reading device 1 that reads image information from a document set on a contact glass 9, an image forming unit having a photosensitive drum 5, a developing device 6, and the like, and an optical writing unit (laser scanning device) 2 that will be described in detail later. And an automatic document feeder (ADF) 3 is mounted on the upper part. In this digital copier, the image reading device 1 is a hinge 1
The image reading device 1 can rotate in the direction of arrow A with the fulcrum 3 as a fulcrum.

When this digital copier is used as a copier, for example, a document to be copied is set in the automatic document feeder 3 and a copy start button (not shown) is pressed.
Then, the originals are fed one by one to a predetermined position on the contact glass 9, where an image is read by the image reading device 1, and the read original is discharged onto a predetermined original discharge tray. Is done. Then, the operation is repeated for all the originals. At a predetermined timing, the photosensitive drum 5 rotates in the direction of arrow B, and the surface thereof is uniformly charged by the charging roller 15 of the charging device.
Then, the laser light emitted from the optical writing unit 2 at a predetermined timing strikes the charged surface, and the photosensitive drum 5
Is exposed in accordance with the image data, and the potential of that portion drops, whereby an electrostatic latent image is formed there. The toner is attached to the electrostatic latent image by the developing device 6 to form a toner image.

On the other hand, a sheet is fed from a sheet feeding section 7 provided at a lower portion of the apparatus main body, and is fed to a registration roller pair 8.
, And is conveyed toward the transfer position at an accurate timing coincident with the image on the photosensitive drum 5.
Then, the toner image on the photosensitive drum 5 is transferred to the sheet at the transfer position, and the sheet is transported by the transport belt 11 to the fixing device 12, where the toner image is fixed.
The sheet is discharged onto a discharge tray 14 outside the apparatus by a discharge roller pair 16. Further, the transfer residual toner is removed from the surface of the photosensitive drum 5 on which the transfer and the separation are completed by the cleaning device 17 to prepare for the next image formation.

Next, the optical writing unit 2 will be described in detail. The optical writing unit 2 has a light source having a semiconductor laser 18 as a light source shown in FIG. 5 and an LD control plate 19 which is a modulation control unit that performs modulation control on the semiconductor laser 18 according to image data to blink or emit light intensely or weakly. Device 20
1, a cylindrical lens 27 shown in FIG. 1, a deflector 21 for deflecting a light beam emitted from the light source device 20, and a light beam deflected by the deflector 21 for scanning the photosensitive drum 5 (FIG. 4) fθ lens 22 and surface tilt correction lens 23, which are imaging lenses that form images on
The above-described cylindrical lens 27, deflector 21, fθ
The housing 24 includes the lens 22, the surface tilt correction lens 23, and the like, and the cover 25 illustrated in FIG.

In the optical writing unit 2, a light exit 20a (shown in FIGS. 2 and 3) for emitting light from the light source device 20 is disposed in the housing 24, and the LD control plate 19 is attached to the housing 24. When the housing 24 is exposed to the outside, the housing 24 is kept in a substantially sealed state.
The optical writing unit 2 includes a light source device 20 and a housing 24, as shown in FIG.
A light source device mounting portion 26 is formed so as to be attachable and detachable in a direction indicated by an arrow C perpendicular to the bottom surface 24a of the housing 24, and the light source device 20 is mounted on the light source device mounting portion 26 as shown in FIG. By covering with a cover 25 shown in FIG. 4, the inside of the housing 24 is kept substantially sealed.

The laser light emitted from the light source device 20 of the optical writing unit 2 passes through the cylindrical lens 27 shown in FIG. 1, and is deflected by a polygon mirror 21b rotated by a polygon motor 21a of a deflector 21. Scanned. The deflector 21 is a polygon motor 2
It has a drive circuit board on which a drive IC for driving 1a is mounted. The laser light deflected and scanned by the polygon mirror 21b passes through a lens system such as an fθ lens 22, a surface tilt correction lens 23, and the like, is reflected by a mirror 28, and moves on the photosensitive drum 5 (FIG. 4) at a constant speed. Scanning is performed in the direction indicated by E, and an electrostatic latent image is formed thereon. A part of the laser light deflected and scanned by the polygon mirror 21b is reflected by the mirror 29 for synchronization detection, passes through the cylinder lens 31 for synchronization detection, and then enters the light receiving surface of the synchronization detection sensor 32. The writing timing for the photosensitive drum 5 is set accordingly.
These components are respectively arranged at predetermined positions shown in FIG. 1 inside the housing 24.

Next, the configuration of the light source device 20 will be described in detail. The LD control plate 19 of the light source device 20 includes a plurality of bosses 3 formed on the holding member 33 as shown in FIG.
4 is fixed by screws. The holding member 33
Is formed with a circular hole 33a substantially at the center, into which the semiconductor laser 18 is fitted and fixed with an adhesive. A collimator lens 35 is attached to the holding member 33 on the side opposite to the side where the semiconductor laser 18 is attached. The collimator lens 35 is fixed to the holding member 33 after adjusting the mounting position, applying an ultraviolet curable resin to the collimator lens 35, and irradiating ultraviolet rays.

The collimator lens 35 of the holding member 33
An aperture forming member 36 having an aperture formed therein is press-fitted and fixed to the mounting side. The LD control plate 19 is screwed and fixed to the holding member 33 as described above, and in that state, the terminal 18a of the semiconductor laser 18 is electrically connected thereto by soldering or the like. Thus, the semiconductor laser 18 and the collimator lens 35
The holding member 33 to which the and the LD control plate 19 are attached is fixed to the L-shaped holding member 37 with screws. The L-shaped holding member 37 has an optical axis Lr of the semiconductor laser 18 shown in FIG.
And a bottom surface 24 a of the housing 24.
And mounting holes 37b, 37b penetrated in a direction perpendicular to the vertical direction. On the other hand, the light source device mounting portion 26 of the housing 24
Is formed with a notch 39 having a width slightly larger than the width W of the L-shaped holding member 37. In the housing 24, two mounting holes 37b of the L-shaped holding member 37,
Screw holes 24b, 24b are formed at positions corresponding to 37b, respectively.

In the optical writing unit 2 shown in FIG. 1, when the light source device 20 is mounted on the housing 24, the side surfaces 37c and 37d on both sides of the L-shaped holding member 37 shown in FIG. 3 are fitted from the upper side along the edges on both sides of the L-shaped holding member 37.
Screws 41, 41 in the mounting holes 37b, 37b shown in FIG.
Into the screw holes 2 of the housing 24.
4b and 24b. As described above, the optical writing unit 2 includes the light source device mounting portion 26 including the notch 39 that allows the light source device 20 to be attached to and detached from the housing 24 in the direction of arrow C perpendicular to the bottom surface 24a of the housing 24. Since the light source device 20 is formed, the light source device 20 can be mounted on the light source device mounting portion 26 by moving the light source device 20 from above the housing 24 in the direction of arrow C, and can be removed. Therefore, the light source device 20 can be easily attached and detached, so that serviceability is good.

The optical writing unit 2 has a configuration in which the light emission port 20a of the light source device 20 is disposed in the housing 24 as shown in FIG. 1, and the LD control plate 19 is exposed outside the housing 24. Therefore, since heat generated from the LD control plate 19 does not affect each component in the housing 24, even if a lens made of resin is used as an optical element in the housing 24, it is not affected. There is no possibility that a thermal deformation or a position change due to a rise in temperature causes a problem in an image.

FIG. 6 is a perspective view similar to FIG. 3 showing another embodiment of the optical writing unit according to the present invention, showing only essential parts.
Parts corresponding to those in FIG. 3 are denoted by the same reference numerals. The optical writing unit according to this embodiment is different from the optical writing unit 2 described with reference to FIGS. 1 to 5 only in that the shape of the L-shaped holding member 47 is different. Thus, the mounting structure between the light source device 20 ′ and the light source device mounting portion 26 on the housing 24 side can be changed in a state where the light source device 20 ′ is mounted on the light source device mounting portion 26. The semiconductor laser 1 is located between the shape holding member 47 and the light source device mounting portion 26.
8 (see FIG. 5) has a labyrinth structure in which there are portions overlapping each other in the optical axis direction (the direction of arrow G) of the emitted laser beam.

That is, the L-shaped holding member 47 forms step portions on both sides to form flanges 47a and 47b, respectively.
When they are mounted at predetermined positions of the housing 24 shown in FIG. 6, the light source device mounting portions 26 on the housing 24 are overlapped with the edges on both sides of the notch 39 by the width Wa, respectively. Thus, the light source device 2
If the part of the light source device 20 'attached to the housing 24 has a labyrinth structure, the tightness between the L-shaped holding member 47 and the housing 24 when the light source device 20' is assembled to the housing 24 can be enhanced. Therefore, dust, dirt, and the like hardly enter the housing 24 of the optical writing unit, so that the dustproofness is improved. Thereby, it is possible to prevent dirt from being attached to the optical element in the housing 24. In addition, since the soundproofing property can be improved, the soundproofing effect against noise generated from the polygon motor (see the polygon motor 21a in FIG. 1) in the housing 24 is also enhanced.

Incidentally, the L-shaped holding members 37 and 47 which are members of the light source devices 20 and 20 'in the above-described embodiments which are attached to the housing 24 are preferably made of a material having a high thermal conductivity. For example, L-shaped holding member 3
7 and 47 may be formed of a material having high thermal conductivity such as aluminum. Then, the L-shaped holding members 37, 47
However, since it plays a role of a heat sink for radiating the heat generated by the heat-generating components on the semiconductor laser 18 and the LD control plate 19, the heat radiation can be promoted. Therefore, it is possible to prevent a defect in an image caused by a thermal deformation or a position change of the collimator lens 35 (see FIG. 5) due to heat generated by the semiconductor laser 18 or the LD control plate 19.

[0023]

As described above, according to the present invention, the following effects can be obtained. According to the optical writing unit of the first aspect and the image forming apparatus of the fifth aspect, the modulation control means for generating heat is exposed to the outside of the housing. There is no such thing as raising the temperature of.
Therefore, it is possible to prevent an image defect caused by an increase in the temperature of each component disposed inside the housing and a deformation or a position change. According to the optical writing unit of the second aspect, the temperature rise in the housing due to the heat generated by the modulation control means can be prevented, and the light source device is perpendicular to the bottom surface of the housing along the light source device mounting portion. Can be pulled out in the direction
It can be easily removed and, conversely, it can be easily attached at the time of installation. Therefore, serviceability is improved.

According to the optical writing unit of the third aspect, since the light source device and the light source device mounting portion on the housing side are assembled by a labyrinth structure, a light flux is provided between the light source device and the light source device mounting portion. Since there are portions overlapping each other in the optical axis direction, the hermeticity of the housing can be improved. Therefore, dust resistance is enhanced. In addition, dirt is less likely to adhere to the components inside the housing, and the soundproofing is enhanced, so that the soundproofing effect against noise generated when the deflector inside the housing is driven is also enhanced. Claim 4
According to the optical writing unit of (1), since the member of the portion attached to the housing of the light source device is formed of a material having high thermal conductivity, the heat generated during operation of the light source device is generated by the material having high thermal conductivity. Its role facilitates heat dissipation. Therefore, it is possible to prevent a problem of an image caused by a position change due to thermal deformation of a lens or the like due to heat generated by the light source device.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of an optical writing unit according to the present invention with a cover removed.

FIG. 2 is an exploded perspective view showing a light source device of the optical writing unit and a part of a housing for mounting the same.

FIG. 3 is a perspective view showing a state where the light source device is attached to a housing.

FIG. 4 is an overall configuration diagram showing a digital copying machine which is an image forming apparatus equipped with the optical writing unit of FIG. 1;

5 is a cross-sectional view of the light source device of FIG. 2 cut from a mounting portion of a semiconductor laser as a center and viewed from a plane.

FIG. 6 is a perspective view similar to FIG. 3, showing only a main part of another embodiment of the optical writing unit according to the present invention.

FIG. 7 is a perspective view illustrating an example of an optical writing unit used in a conventional image forming apparatus.

FIG. 8 is a perspective view showing an example of a conventional light source device.

FIG. 9 is a perspective view illustrating an example of an optical writing unit in which an upper surface is closed by a bottom plate of the image reading apparatus.

[Explanation of symbols]

 2: Optical writing unit 18: Semiconductor laser (light source) 19: LD control plate (modulation control means) 20, 20 ': Light source device 21: Deflector 22: fθ lens 23: Surface tilt correction lens 24: Housing 25: Cover 26: light source device mounting part 33: holding member 37, 47: L-shaped holding member

Claims (5)

[Claims] 1. A light source device having a light source and modulation control means for modulating the light source in accordance with image data; a deflector for deflecting a light beam emitted from the light source device; An optical imaging unit comprising: an imaging lens that forms an image of the light beam on the surface to be scanned; a housing that houses the deflector and the imaging lens; and a cover that closes the housing in a substantially sealed state. A light emission port for emitting light of the light source device is arranged in the housing, and the housing is kept substantially sealed with the modulation control means being exposed to the outside of the housing. Optical writing unit. 2. The optical writing unit according to claim 1, wherein a light source device mounting portion is formed in the housing so that the light source device can be mounted and removed in a direction perpendicular to a bottom surface of the housing. An optical writing unit, wherein the inside of the housing is kept substantially sealed by covering the cover with the light source device attached to an attachment portion. 3. The optical writing unit according to claim 2, wherein an assembling structure between the light source device and the light source device mounting portion on the housing side is such that the light source device is mounted on the light source device mounting portion. An optical writing unit, wherein a labyrinth structure is formed between the light source device and the light source device mounting portion so as to overlap each other in the optical axis direction of the light flux. 4. The light source device according to claim 1, wherein a member for holding the light source and the modulation control means of the light source device is formed of a material having high thermal conductivity. Optical writing unit. 5. An image forming apparatus comprising the optical writing unit according to claim 1.