JP2006178372A - Scanner and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a scanner with which laser beams emitted from a plurality of laser light emitting parts are made incident on an optical deflection means with high accuracy in a sub-scanning direction and the accurate deflection and scanning of a plurality of laser light beams are assured, and to provide an image forming apparatus equipped with the scanner. <P>SOLUTION: In a laser irradiation optical part 18, a second slit plate 28 on which two second slits 31 arranged in parallel with a distance in a sub-scanning direction Y are opened is provided between a reflection mirror 17 which synthesizes the optical paths of two laser light beams emitted from laser light emitting parts 24 which are perpendicularly arranged as a pair so as to coincide in a main scanning direction X, and a cylindrical lens 29 for converging two laser light beams with which a polygon mirror 17 is irradiated in the sub-scanning direction Y. The error of the two laser light beams made incident on the polygon mirror 17 is reduced not only in the main scanning direction X but also in the sub-scanning direction Y by respective second slits 31. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a laser printer, and a scanner device provided in the image forming apparatus.

As an electrophotographic color laser printer, there is known a tandem type color laser printer provided with four photosensitive drums on which electrostatic latent images of respective colors are formed corresponding to yellow, magenta, cyan and black. .
In a tandem type laser printer, the toner images of each color are transferred from each photosensitive drum to the paper that sequentially passes through each photosensitive drum, and the colors are sequentially superimposed, so that a color image is formed at almost the same speed as a monochrome laser printer. Can do.

In such a tandem type color laser printer, it is necessary to form electrostatic latent images corresponding to the respective colors on the four photosensitive drums, and accordingly, four scanner devices corresponding to the four photosensitive drums. Is required.
However, if four scanner devices are provided, an increase in cost and an increase in size of the device are inevitable. Therefore, the laser beams emitted from the four semiconductor lasers corresponding to the respective colors are optically combined in the main scanning direction by a plurality of half mirrors, and then mutually in the sub-scanning direction with respect to the same deflection reflection surface of one deflector. By making the light incident at different angles, the optical path is separated in the sub-scanning direction along with the deflection scanning in the main scanning direction, and the electrostatic latent images corresponding to the respective colors are respectively applied to the four photosensitive drums by one tandem scanning optical device. It is proposed to form (for example, refer to Patent Document 1).
JP 2003-215487 A

  However, in the tandem scanning optical device described in Patent Document 1, laser beams emitted from four semiconductor lasers are converted into parallel light beams by a collimating optical system, and optical paths are synthesized in the main scanning direction by a plurality of mirrors. Due to the processing accuracy of each mirror or the positional accuracy of the collimating optical system, an error may occur in each laser beam in the sub-scanning direction. When such an error occurs, an error occurs in the incident angle with respect to the deflecting reflection surface of the deflector, which causes a problem that the deflector cannot perform deflection scanning with high accuracy.

  An object of the present invention is to allow laser light emitted from a plurality of laser light emitting units to be incident on a light deflecting unit with high accuracy in the sub-scanning direction, thereby ensuring accurate deflection and scanning of the plurality of laser beams. Another object of the present invention is to provide a scanner device and an image forming apparatus including the scanner device.

  In order to achieve the above object, a first aspect of the present invention is a scanner device, comprising: a plurality of laser light emitting units that emit laser light; and a laser beam emitted from the plurality of laser light emitting units in a main scanning direction. And a plurality of laser beams emitted from the plurality of laser light emitting units are arranged between the plurality of laser light emitting units and the light deflecting unit in the laser beam passing direction. A plurality of laser beams emitted from a plurality of the laser light emitting units, which are arranged between the optical path combining unit and the light deflecting unit in the laser beam passing direction. Correspondingly, the aperture hole formed is provided with a slit member arranged side by side in the sub-scanning direction.

  According to such a configuration, the plurality of laser beams matched in the main scanning direction by the optical path combining unit are then mutually connected in the sub scanning direction by the aperture holes arranged in the sub scanning direction in the slit member. After the position is adjusted, the light enters the light deflecting means. For this reason, since the plurality of laser beams are incident not only in the main scanning direction but also in the sub-scanning direction and then incident on the light deflecting unit, the plurality of laser beams are accurately deflected and scanned by the light deflecting unit. can do.

In addition, in this configuration, the apertures through which the laser beams pass are provided in the same slit member, so that the relative positional accuracy between the laser beams is high, and the accuracy of the laser beams incident on the light deflecting means is high. A good relative position can be ensured. Therefore, accurate deflection and scanning between the laser beams can be ensured.
The invention described in claim 2 is characterized in that, in the invention described in claim 1, a guide member for slidably guiding the slit member and positioning the slit member is provided. .

According to such a configuration, in the guide member, since the slit member is slidably guided and positioned, the slit member is positioned with high accuracy, and each aperture hole arranged in the slit member is accurately arranged. can do. Therefore, it is possible to achieve more accurate deflection and scanning of each laser beam.
According to a third aspect of the present invention, in the first or second aspect of the present invention, the laser light emitting units are provided corresponding to a plurality of the laser light emitting units, and each of the laser light emitting units and the optical path in a laser light passing direction. It is characterized in that it is provided with stray light preventing means for preventing stray light of the laser light emitted from each of the laser light emitting portions, which is disposed between the combining means.

According to such a configuration, the stray light of the laser light emitted from each laser light emitting unit can be prevented by the stray light preventing means. Therefore, it is possible to prevent laser light emitted from a specific laser light emitting unit from interfering with laser light emitted from other laser light emitting units, and to accurately deflect and scan each laser light. Can be achieved.
The invention described in claim 4 is characterized in that, in the invention described in claim 3, the stray light preventing means limits a cross-sectional shape of the laser beam directed to the optical path combining means.

According to such a configuration, the stray light prevention unit limits the cross-sectional shape of the laser light that travels toward the optical path synthesis unit. Therefore, it is possible to more reliably prevent laser light emitted from a specific laser light emitting unit from interfering with laser light emitted from other laser light emitting units.
According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the plurality of laser light emitting units are arranged as one set, and the slit member is provided for each set. Each of the aperture holes is formed corresponding to each set of the laser light emitting portions.

According to such a configuration, one slit member is provided for each set of laser light emitting units, and a diaphragm hole is formed corresponding to each set of laser light emitting units. Therefore, by arranging a plurality of laser light emitting units in a plurality of sets, it is possible to achieve accurate deflection and scanning of each laser beam while ensuring an efficient layout.
According to a sixth aspect of the present invention, in the invention according to any of the first to fifth aspects, the plurality of laser light emitting units are symmetrically arranged as a set of two with respect to the light deflecting unit, Two light beams are provided corresponding to each set of laser beams that are emitted from each set of the laser light emitting units and deflected and scanned by the light deflecting unit, and each set of laser beams has a constant velocity on the image plane. And an optical path forming means for emitting each laser beam that has passed through each fθ lens from a different position.

  According to such a configuration, the laser light emitted from the laser light emitting units of each pair arranged symmetrically as a pair with respect to the light deflecting means is irradiated to the light deflecting means from the symmetrical direction, and deflected and scanned. Then, the light passes through the fθ lens and is converted into a light beam having a constant velocity on the image plane. Each laser beam is emitted from a different position by the optical path forming means. Therefore, while the apparatus can be configured compactly, each laser beam deflected and scanned with high accuracy can be emitted from different positions.

According to a seventh aspect of the present invention, there is provided an image forming apparatus comprising: the scanner apparatus according to any one of the first to sixth aspects; and a plurality of lasers deflected and scanned in a main scanning direction by the light deflecting unit. And a plurality of photoconductors on which electrostatic latent images are respectively formed by irradiation with light.
According to such a configuration, an electrostatic latent image is formed on each photoconductor by each laser beam emitted from the scanner device. Therefore, an accurate electrostatic latent image can be formed on each photoconductor to achieve accurate color image formation.

  According to an eighth aspect of the present invention, there is provided an image forming apparatus, comprising: a plurality of laser light emitting units that emit laser light; and the laser light emitted from the plurality of laser light emitting units is deflected and scanned in a main scanning direction. And a plurality of laser light beams emitted from the plurality of laser light emitting units in the main scanning direction. The optical path synthesizing means to be matched with each other in the laser beam passing direction is formed between the optical path synthesizing means and the light deflecting means, and formed corresponding to the plurality of laser beams emitted from the plurality of laser emission units. And a plurality of laser beams that are deflected and scanned in the main scanning direction by the light deflecting means, respectively, It is characterized by comprising a plurality of photoreceptors more electrostatic latent image is formed.

  According to such a configuration, the plurality of laser beams matched in the main scanning direction by the optical path combining unit are then mutually connected in the sub scanning direction by the aperture holes arranged in the sub scanning direction in the slit member. After the position is adjusted, the light enters the light deflecting means. For this reason, since the plurality of laser beams are incident not only in the main scanning direction but also in the sub-scanning direction and then incident on the light deflecting unit, the plurality of laser beams are accurately deflected and scanned by the light deflecting unit. can do.

In addition, in this configuration, the apertures through which the laser beams pass are provided in the same slit member, so that the relative positional accuracy between the laser beams is high, and the accuracy of the laser beams incident on the light deflecting means is high. A good relative position can be ensured. Therefore, accurate deflection and scanning between the laser beams can be ensured.
An electrostatic latent image is formed on each photoconductor by each laser beam deflected and scanned in the main scanning direction by the light deflecting unit. Therefore, an accurate electrostatic latent image can be formed on each photoconductor to achieve accurate color image formation.

According to a ninth aspect of the present invention, in the invention according to the seventh or eighth aspect, the four photosensitive members are provided, and four photosensitive members are provided corresponding to each of the photosensitive members, and development of different colors is performed. Developer supplying means for supplying the developer to each of the photoconductors is provided.
According to such a configuration, the electrostatic latent image formed on each photoconductor is developed with different colors of developer by the developer supply means provided corresponding to each photoconductor. Therefore, a color image can be formed at almost the same speed as a monochrome image by sequentially superimposing the developer images formed on the respective photoconductors.

According to the first aspect of the present invention, in the light deflection means, a plurality of laser beams can be deflected and scanned with high accuracy even between the laser beams.
According to the second aspect of the invention, it is possible to achieve more accurate deflection and scanning of each laser beam.
According to the third aspect of the present invention, accurate deflection and scanning of each laser beam can be achieved.

According to the fourth aspect of the present invention, it is possible to more reliably prevent the laser light emitted from the specific laser light emitting unit from interfering with the laser light emitted from the other laser light emitting units. Can do.
According to the fifth aspect of the present invention, by arranging a plurality of laser light emitting units in a plurality of sets, it is possible to achieve accurate deflection and scanning of each laser beam while ensuring an efficient layout. Can do.

According to the sixth aspect of the present invention, the laser beam deflected and scanned with high accuracy can be emitted from different positions while the apparatus can be configured compactly.
According to the seventh aspect of the present invention, an accurate electrostatic latent image can be formed on each photoconductor to achieve accurate color image formation.

According to the invention described in claim 8, in the optical deflection means, a plurality of laser beams can be deflected and scanned with high precision even between the laser beams. As a result, an electrostatic latent image with high accuracy can be obtained. Can be formed on each photoconductor to achieve accurate color image formation.
According to the ninth aspect of the present invention, a color image can be formed at substantially the same speed as a monochrome image if the developer images formed on the respective photoconductors are sequentially color-superposed.

(Overall configuration of color laser printer)
FIG. 1 is a side sectional view showing an embodiment of a color laser printer as an image forming apparatus of the present invention.
The color laser printer 1 is a horizontal tandem type color laser printer in which a plurality of process units 13 are arranged in parallel in the horizontal direction, and the paper 3 is fed into a box-shaped main casing 2. A paper feed unit 4 for paper, an image forming unit 5 for forming an image on the fed paper 3, and a paper discharge unit 6 for discharging the paper 3 on which the image is formed are provided.
(Configuration of paper feed unit)
The paper feed unit 4 is provided at a paper cassette 7 provided at the bottom of the main body casing 2 and above the front side of the paper cassette 7 (in the following description, the right side in FIG. 1 is the front side and the left side is the rear side). A paper feed roller 8, a paper feed path 9 provided above the front side of the paper feed roller 8, a pair of transport rollers 10 provided in the middle of the paper feed path 9, and a downstream end of the paper feed path 9. And a pair of registration rollers 11 provided.

The sheets 3 are stacked in the sheet cassette 7, and the sheet 3 at the top is sent out to the sheet feeding path 9 by the rotation of the sheet feeding roller 8.
The paper feed path 9 has an upstream end adjacent to the paper feed roller 8 at the lower side so that the paper 3 is fed forward, and a downstream end at the upper side of the conveyance belt described later. Adjacent to 61, it is formed as a substantially U-shaped sheet 3 conveyance path so that the sheet 3 is discharged rearward.

The paper 3 sent to the paper feed path 9 is transported by the transport roller 10 in the paper feed path 9, the transport direction is reversed in the front and back direction, and after registration by the registration roller 11, The paper is discharged toward
(Configuration of image forming unit)
The image forming unit 5 includes a scanner unit 12 as a scanner device, a process unit 13, a transfer unit 14, and a fixing unit 15.
(Configuration of scanner unit)
The scanner unit 12 is arranged above a plurality of process units 13 to be described later in the upper part in the main body casing 2. FIG. 2 is a side view of the main configuration of the scanner unit 12 as viewed from the side, and FIG. 6 is a side sectional view of the scanner unit 12 as viewed from the side. 2 and 6, the scanner unit 12 includes a scanner casing 16, a polygon mirror 17 serving as a light deflecting unit provided in the scanner casing 16, and a laser for irradiating the polygon mirror 17 with laser light. The laser beam deflected and scanned by the irradiation optical unit 18 and the polygon mirror 17 is converted into a laser beam corresponding to each color through the fθ lens 19 that converts the laser beam deflected and scanned into a light beam having a constant velocity on the image plane. And a laser emission optical unit 20 as optical path forming means.

  As shown in FIG. 6, the scanner casing 16 has a box shape, and an emission window 21 corresponding to each color is formed on the bottom wall 43. The respective emission windows 21 are provided at different positions in the front-rear direction and spaced from each other. The yellow emission window 21Y, the magenta emission window 21M, and the cyan emission window are sequentially arranged from the front to the rear corresponding to the respective colors. 21C is formed as a black exit window 21K.

One polygon mirror 17 is provided on the motor substrate 22 at the center in the front-rear direction in the scanner casing 16 for four laser light emitting units 24 described later.
FIG. 3 is a plan view of the main configuration of the scanner unit 12 as viewed from above. As shown in FIG. 3, the polygon mirror 17 is formed in a polyhedron (for example, a hexahedron) having a plurality of reflecting surfaces, and is accommodated in the motor substrate 22 around a rotation shaft 23 provided at the center thereof. The scanner motor is rotated at high speed by the power of the scanner motor.

The motor substrate 22 is fixed to the bottom wall 43 of the scanner casing 16 via a boss (not shown).
The laser irradiation optical unit 18 is provided symmetrically with respect to the polygon mirror 17. Each laser irradiation optical unit 18 includes a laser light emitting unit 24, a collimating lens 25, a first slit plate 26 as stray light preventing means, a reflection mirror 27 as optical path synthesizing means, and a second slit plate 28 as a slit member. And a cylindrical lens 29 as a set.

  The laser emitting units 24 are made of a semiconductor laser or the like, and are provided in pairs in each laser irradiation optical unit 18. Each laser light emission part 24 is arrange | positioned so that the optical path of the laser beam light-emitted from each laser light emission part 24 may mutually orthogonally cross. Further, as shown in FIG. 2, the laser light emitting units 24 are arranged at intervals in the sub-scanning direction Y (see FIG. 4).

  FIG. 4 is a perspective view of the laser irradiation optical unit 18 of the scanner unit 12 as viewed obliquely from the front. As shown in FIG. 4, the collimator lens 25 is provided (two) corresponding to each laser light emitting unit 24. Each collimator lens 25 is provided on the downstream side of each laser light emitting unit 24 in the direction in which the laser light emitted from each laser light emitting unit 24 passes (hereinafter simply referred to as the laser light passing direction), and each laser light emission. It is arranged so as to face the part 24.

Laser light emitted from each laser light emitting unit 24 is converted by each collimator lens 25 into a parallel light beam.
As shown in FIG. 3, the first slit plate 26 is formed of a substantially L-shaped plate in which two flat plates are continuous in a substantially right angle direction, and each flat plate prevents stray light as shown in FIG. First slits 30 for opening are respectively opened. The slits 30 are formed in a long hole shape extending in the main scanning direction X, and are arranged in the sub-scanning direction Y at intervals corresponding to the laser light emitting units 24. The first slit plate 26 is arranged such that each first slit 30 is arranged on the downstream side of each collimating lens 25 in the laser beam passing direction and is opposed to each collimating lens 25.

Each laser beam that has passed through each collimator lens 25 is limited in cross-sectional shape perpendicular to the laser beam passing direction by each first slit 30 of the first slit plate 26, and is thereby emitted from each laser emission unit 24. The stray light of the laser beam is prevented.
The reflection mirror 27 is disposed on the downstream side of each first slit 30 in the laser beam passing direction, and is inclined at approximately 45 ° with respect to each flat plate of the substantially L-shaped first slit plate 26. Is provided. In this reflection mirror 27, the laser beam that has passed through one slit 30 passes straight through on the upper side, and the laser beam that has passed through the other slit 30 is reflected by approximately 90 ° on the lower side to be substantially perpendicular. It is formed so as to be refracted. As a result, the optical paths of the two laser beams emitted in the directions orthogonal to each other from the two laser emission units 24 are combined so as to coincide in the main scanning direction X.

  The second slit plate 28 is disposed on the downstream side of the reflection mirror 27 in the laser beam passing direction. The second slit plate 28 is formed of a substantially rectangular flat plate, and second slits 31 serving as aperture holes are opened corresponding to the respective laser light emitting units 24. The second slits 31 are formed in a long hole shape extending in the main scanning direction X, and are arranged in parallel at intervals corresponding to the laser light emitting units 24 in the sub-scanning direction (see FIG. 4). Has been. These second slits 31 are formed to have a smaller opening area than the first slits 30 formed in the first slit plate 26 so that each laser beam can be narrowed down.

Then, the laser beams combined with the optical path in the main scanning direction X by the reflection mirror 27 are mutually adjusted in position in the sub-scanning direction Y when passing through the second slits 31.
FIG. 5 is a perspective view of the second slit 31 as viewed from the front. As shown in FIG. 5, the second slit plate 28 is fixed on a guide member 32 that stands from the bottom wall 43 of the scanner casing 16.

  That is, the guide member 32 includes two slide rods 33 that are opposed to each other with the second slit plate 28 interposed therebetween. Each slide rod 33 is formed with a U-shaped slide groove 34 that is open at one end, and the slide rods 33 are arranged at an interval to sandwich the second slit plate 28 from each other. Are opened from the bottom wall 43 with their open sides facing each other.

  The second slit plate 28 is inserted into the slide grooves 34 of the slide rods 33 from above in the width direction (longitudinal direction and the direction perpendicular to the vertical direction), and then the second slit plate 28 The guide member 32 is mounted by being guided by sliding downward along the slide grooves 34 until the lower end portion comes into contact with the bottom wall 43. The second slit plate 28 is positioned by the slide rods 33 and the bottom wall 43 while being attached to the guide member 32.

The cylindrical lens 29 is disposed downstream of the second slit 28 and upstream of the polygon mirror 17 in the laser light passing direction. The cylindrical lens 29 has a refractive power only in the sub-scanning direction Y.
As shown in FIG. 2, each laser beam that has passed through the second slit 28 of the second slit plate 28 is refracted so as to converge in the sub-scanning direction Y by the cylindrical lens 29, and then enters the polygon mirror 17. The

  As shown in FIG. 3, the two laser irradiation optical units 18 are arranged on opposite sides so as to be symmetrical with respect to the polygon mirror 17, and in the cylindrical lens 29 of each laser irradiation optical unit 18. The two laser beams refracted so as to converge in the sub-scanning direction Y are incident on the polygon mirror 17 from opposite sides. As a result, four laser beams are incident on the polygon mirror 17 as a set from the opposite sides.

  In the polygon mirror 17, two sets (four) of laser beams incident from opposite sides are deflected and scanned in the main scanning direction X by high-speed rotation of the polygon mirror 17. Since the two laser beams in each set are incident on the reflection surface of the polygon mirror 17 at different angles, the two laser beams are gradually reflected from the reflection surface at angles that are separated from each other in the sub-scanning direction Y (vertical direction).

Two fθ lenses 19 are provided so as to face each other across the polygon mirror 17 in a direction orthogonal to the direction in which each set of laser light is incident on the polygon mirror 17 so as to correspond to the two sets of laser light. Is provided.
Each fθ lens 19 converts the two laser beams incident on the polygon mirror 17 from each laser irradiation optical unit 18 and scanned in the main scanning direction X by the polygon mirror 17 into luminous fluxes having a constant velocity on the image plane.

As shown in FIG. 6, the laser emission optical unit 20 is provided corresponding to each color. That is, the laser emission optical unit 20 includes four parts, a yellow optical unit 20Y, a magenta optical unit 20M, a cyan optical unit 20C, and a black optical unit 20K, corresponding to each color.
The yellow optical unit 20Y is disposed at the forefront in the front-rear direction, and reflects two lasers 35a and 35b that reflect the laser beam that has passed through the upper side of one fθ lens 19, and the laser beams reflected by the reflecting mirrors 35a and 35b. And a toroidal lens 36 that converges in the sub-scanning direction Y.

The laser light that has passed through the upper side of one fθ lens 19 is first reflected obliquely rearward and upward by the reflecting mirror 35a in the yellow optical section 20Y, and then reflected downward in the vertical direction by the reflecting mirror 35b and then the toroidal lens. 36 passes through in the vertical direction and exits from the yellow exit window 21Y.
The magenta optical unit 20M is disposed between the polygon mirror 17 and the yellow optical unit 20Y, and includes three reflecting mirrors 37a, 37b, and 37c that reflect the laser light that has passed under one of the fθ lenses 19, and the reflecting mirror. And a toroidal lens 38 for converging the laser beams reflected by 37a, 37b and 37c in the sub-scanning direction Y.

The laser light that has passed under one of the fθ lenses 19 is first reflected upward by the reflecting mirror 37a, then reflected backward by the reflecting mirror 37b, and then vertically reflected by the reflecting mirror 37c. After being reflected downward in the direction, it passes through the toroidal lens 38 in the vertical direction and is emitted from the magenta exit window 21M.
The cyan optical unit 20C is disposed between the polygon mirror 17 and the black optical unit 20K, and reflects three laser mirrors 39a, 39b, and 39c that reflect the laser light that has passed through the lower side of the other fθ lens 19. And a toroidal lens 40 for converging the laser beams reflected by 39a, 39b and 39c in the sub-scanning direction Y.

The laser light that has passed through the lower side of the other fθ lens 19 is first reflected upward by the reflecting mirror 39a in the cyan optical unit 20C, then reflected forward by the reflecting mirror 39b, and then vertically reflected by the reflecting mirror 39c. After being reflected downward in the direction, it passes through the toroidal lens 40 in the vertical direction and is emitted from the cyan emission window 21C.
The black optical unit 20K is arranged at the rearmost in the front-rear direction, and reflects two lasers 41a and 41b that reflect the laser beam that has passed through the upper side of the other fθ lens 19; And a toroidal lens 42 that converges in the sub-scanning direction Y.

The laser beam that has passed through the upper side of the other fθ lens 19 is first reflected obliquely forward and upward by the reflecting mirror 41a at the black optical unit 20K, and then reflected vertically downward by the reflecting mirror 41b and then the toroidal lens 42. In the vertical direction and is emitted from the black emission window 21K.
The magenta optical unit 20M and the cyan optical unit 20C are arranged symmetrically with respect to the polygon mirror 17, and the yellow optical unit 20Y and the black optical unit 20K are outside the magenta optical unit 20M and the cyan optical unit 20C. Are arranged symmetrically with respect to the polygon mirror 17.
(Configuration of process part)
As shown in FIG. 1, a plurality of process units 13 are provided corresponding to a plurality of colors of toner. In other words, the process unit 13 includes four units, that is, a yellow process unit 13Y, a magenta process unit 13M, a cyan process unit 13C, and a black process unit 13K. These process units 13 are sequentially arranged in parallel so as to overlap in the horizontal direction at intervals from the front to the rear.

Each process unit 13 includes a photosensitive drum 51 as a photosensitive member, a scorotron charger 52, and a developing cartridge 53.
The photosensitive drum 51 has a cylindrical shape, and a drum main body formed by a positively chargeable photosensitive layer whose outermost layer is made of polycarbonate or the like, and a drum shaft extending along the axial direction of the drum main body at the axial center of the drum main body. And has. The drum body is provided so as to be rotatable with respect to the drum shaft, and the drum shaft is supported in a non-rotatable manner on both side walls of the process unit 13 in the width direction (the front-rear direction and the direction perpendicular to the vertical direction, the same applies hereinafter). . The photosensitive drum 51 is rotationally driven in the same direction (clockwise in the drawing) as the movement direction of the conveyance belt 61 at a contact position with the conveyance belt 61 described later during image formation.

The scorotron charger 52 is a positively charged scorotron charger that includes a wire and a grid and generates a corona discharge when a charging bias is applied. The scorotron charger 52 does not contact the photosensitive drum 51 behind the photosensitive drum 51. Opposing to each other with an interval.
The developing cartridge 53 includes a developing roller 56 as a developer supply means, a supply roller 57, and a layer thickness regulating blade 58 in the casing.

  The developing roller 56 is disposed opposite the photosensitive drum 51 in front of the photosensitive drum 51. In the developing roller 56, a metal roller shaft is covered with a roller portion made of an elastic member such as a conductive rubber material. More specifically, the roller portion is coated with an elastic roller layer made of conductive urethane rubber, silicone rubber, EPDM rubber or the like containing carbon fine particles, and the surface of the roller layer. And a two-layer structure with a coat layer mainly composed of polyimide resin or the like. The roller shaft of the developing roller 56 is rotatably supported on both side walls in the width direction of the housing of the developing cartridge 53, and a developing bias is applied during image formation.

The supply roller 57 is disposed in front of the developing roller 56 so as to face the developing roller 56 and is in pressure contact with the developing roller 56. The supply roller 57 has a metal roller shaft covered with a roller portion made of a conductive sponge member. The roller shaft of the supply roller 57 is rotatably supported on both side walls in the width direction of the housing of the developing cartridge 53.
The layer thickness regulating blade 58 is made of a metal leaf spring material, and has a semicircular cross-section pressing member made of insulating silicone rubber at the tip. The layer thickness regulating blade 58 is supported by the housing of the developing cartridge 53 above the developing roller 56, and the pressing member at the tip (lower end) thereof is pressed against the developing roller 56 from the upper front side. .

  The upper portion of the housing of the developing cartridge 53 is formed as a toner storage chamber 55 for storing toner, and each color toner is stored. That is, the toner storage chamber 55 of the yellow process section 13Y stores a positively chargeable nonmagnetic one-component polymerized toner having a yellow color. The toner storage chamber 55 of the magenta process unit 13M stores a positively chargeable nonmagnetic one-component polymerized toner having a magenta color. In the toner storage chamber 55 of the cyan process unit 13C, positively charged nonmagnetic one-component polymerized toner having a cyan color is stored. In the toner storage chamber 55 of the black process unit 13K, positively charged nonmagnetic one-component polymerized toner having a black color is stored.

  More specifically, for each color toner, a substantially spherical polymer toner obtained by a polymerization method is used. The polymerization toner is a known polymerization such as a suspension polymerization of a styrene monomer such as styrene or an acrylic monomer such as acrylic acid, alkyl (C1 to C4) acrylate, or alkyl (C1 to C4) methacrylate. The main component is a binder resin obtained by copolymerization according to the method, and a toner base particle is formed by adding a colorant, a charge control agent, a wax, etc. to this, and further improves the fluidity. In order to achieve this, an external additive is added.

  As the colorant, the above-mentioned yellow, magenta, cyan and black colorants are blended. Moreover, as a charge control agent, for example, an ionic monomer having an ionic functional group such as an ammonium salt and an ionic monomer such as a styrene monomer or an acrylic monomer can be copolymerized. A charge control resin obtained by copolymerization with a monomer is blended. As external additives, for example, powders of metal oxides such as silica, aluminum oxide, titanium oxide, strontium titanate, cerium oxide and magnesium oxide, inorganic powders such as carbide powders and metal salt powders are blended. Has been.

  In each process unit 13, the toner of each color stored in each toner storage chamber 55 is supplied to the supply roller 57 at the time of image formation, and is supplied to the developing roller 56 by the rotation of the supply roller 57. At this time, the toner is positively frictionally charged between the supply roller 57 and the developing roller 56 to which a developing bias is applied. The toner supplied onto the developing roller 56 enters between the layer thickness regulating blade 58 and the developing roller 56 as the developing roller 56 rotates, and becomes a thin layer having a constant thickness. It is carried on.

  On the other hand, the scorotron charger 52 generates a corona discharge by applying a charging bias to uniformly positively charge the surface of the photosensitive drum 51. The surface of the photosensitive drum 51 is uniformly positively charged by the scorotron charger 52 as the photosensitive drum 51 rotates, and then exposed by high-speed scanning of the laser light emitted from the emission window 21 of the scanner unit 12. Then, an electrostatic latent image of each color corresponding to the image to be formed on the paper 3 is formed.

When the photosensitive drum 51 further rotates, when the toner carried on the surface of the developing roller 56 and positively charged toner comes into contact with the photosensitive drum 51 by the rotation of the developing roller 56, The electrostatic latent image formed on the surface, that is, the surface of the photosensitive drum 51 that is uniformly positively charged, is supplied to an exposed portion that is exposed to laser light and has a lowered potential. As a result, the electrostatic latent image on the photosensitive drum 51 is visualized, and a toner image by reversal development is carried on the surface of the photosensitive drum 51 corresponding to each color.
(Configuration of transfer section)
The transfer unit 14 is disposed along the front-rear direction in the main body casing 2 above the paper cassette 7 and below the process unit 13. The transfer unit 14 includes a drive roller 59, a driven roller 60, a conveyance belt 61, a transfer roller 62, and a belt cleaning unit 63.

The drive roller 59 is disposed on the lower rear side of the photosensitive drum 51 of the black process unit 13K. The drive roller 59 is driven to rotate in the direction opposite to the rotation direction of the photosensitive drum 51 (counterclockwise in the figure) during image formation.
The driven roller 60 is disposed on the front lower side of the photosensitive drum 51 of the yellow process unit 13Y and is opposed to the driving roller 59 in the front-rear direction. The driven roller 60 is driven and rotated in the same direction as the driving roller 59 (counterclockwise in the figure) when the driving roller 59 is driven to rotate.

  The conveyance belt 61 is an endless belt, and is formed of a conductive polycarbonate or polyimide resin in which conductive particles such as carbon are dispersed. The conveyor belt 61 is wound between the driving roller 59 and the driven roller 60, and the wound outer contact surface is in contact with all of the photosensitive drums 51 of the process units 13. Is arranged.

The driven roller 60 is driven by the driving roller 59, and the conveying belt 61 is exposed between the driving roller 59 and the driven roller 60 on the contact surface facing the photosensitive drum 51 of each process unit 13. In order to rotate in the same direction as the drum 51, it is rotated in the direction indicated by the arrow A (counterclockwise in the figure).
The transfer roller 62 is disposed so as to face the photosensitive drum 51 of each process unit 13 and the conveyor belt 61 in the conveyor belt 61 wound between the driving roller 59 and the driven roller 60. Each transfer roller 62 has a metal roller shaft covered with a roller portion made of an elastic member such as a conductive rubber material. The roller shaft of the transfer roller 62 extends along the width direction and is rotatably supported, and a transfer bias is applied during transfer. Each transfer roller 62 rotates in the same direction (counterclockwise in the figure) as the circumferential movement direction of the conveyor belt 61 on the contact surface that faces and contacts the conveyor belt 61.

  Then, the sheet 3 fed from the sheet feeding unit 4 is conveyed from the front to the rear by the conveyor belt 61 that is circulated by driving of the driving roller 59 and driven of the driven roller 60. It is conveyed so as to sequentially pass through the image forming positions between the 13 photosensitive drums 51. During the conveyance, the toner images corresponding to the respective colors carried on the photosensitive drums 51 of the respective process units 13 are sequentially transferred, whereby a color image is formed on the paper 3.

  That is, for example, when a yellow toner image carried on the surface of the photosensitive drum 51 of the yellow process unit 13Y is transferred to the sheet 3, the magenta toner carried on the surface of the photosensitive drum 51 of the magenta process unit 13M is then transferred. The toner image is transferred onto the sheet 3 on which the yellow toner image has already been transferred, and the cyan toner image carried on the surface of the photosensitive drum 51 of the cyan process unit 13C and the black process unit 13K are similarly operated. The black toner image carried on the surface of the photosensitive drum 51 is transferred in an overlapping manner, whereby a color image is formed on the paper 3.

  In forming such a color image, the color laser printer 1 forms a monochrome image because each process unit 13 has a tandem apparatus configuration in which a plurality of process units 13 are provided corresponding to each color. A toner image corresponding to each color can be formed at almost the same speed as the speed, thereby achieving rapid color image formation. Therefore, it is possible to form a color image while reducing the size.

The belt cleaning unit 63 is disposed below the conveyance belt 61 and opposed to the black process unit 13K with the conveyance belt 61 interposed therebetween.
The belt cleaning unit 63 is disposed so as to come into contact with the surface of the transport belt 61, and a primary cleaning roller 64 for scraping off paper dust and toner adhering to the surface of the transport belt 61, and the primary cleaning thereof. The secondary cleaning roller 65 is disposed in contact with the roller 64 and electrically collects paper dust, toner, and the like scraped off by the primary cleaning roller 64, and contacts the secondary cleaning roller 65 to perform secondary cleaning. A scraping blade 66 for scraping the paper dust and toner collected by the roller 65 and a cleaning box 67 for storing the paper dust and toner scraped by the scraping blade 66 are provided.

In the belt cleaning unit 63, paper dust or toner attached to the surface of the conveyance belt 61 is first scraped off by the primary cleaning roller 64 and then scraped off by the primary cleaning roller 64. And the like are electrically collected by the secondary cleaning roller 65. Thereafter, paper dust and toner collected by the secondary cleaning roller 65 are scraped off by the scraping blade 66 and then stored in the cleaning box 67.
(Configuration of fixing unit)
The fixing unit 15 is disposed behind the transfer unit 14. The fixing unit 15 includes a heating roller 68, a pressure roller 69, and a conveyance roller 70. The heating roller 68 is made of a metal base tube having a release layer formed on the surface thereof, and a halogen lamp is provided along the axial direction thereof. Then, the surface of the heating roller 68 is heated to the fixing temperature by the halogen lamp. The pressure roller 69 is provided so as to press the heating roller 68. Further, the transport roller 70 is composed of a pair of upper and lower rollers, and is disposed behind the heating roller 68 and the pressure roller 69.

The color image transferred onto the paper 3 is then conveyed to the fixing unit 15 and heated and pressed while the paper 3 passes between the heating roller 68 and the pressure roller 69. It is heat-fixed on the paper 3. The heat-fixed paper 3 is sent to the paper discharge unit 6 by the transport roller 70.
(Configuration of paper output unit)
The paper discharge unit 6 includes a paper discharge path 71, a paper discharge roller 72, and a paper discharge tray 73.

  The paper discharge path 71 has an upstream end adjacent to the conveyance roller 70 in the lower part so that the paper 3 is fed backward, and a downstream end in the upper part to the paper discharge roller 72. Adjacent and formed as a substantially U-shaped paper 3 conveyance path so that the paper 3 is discharged forward. The paper discharge roller 72 is provided as a pair of rollers at the downstream end of the paper discharge path 71. The discharge tray 73 is formed on the upper surface of the main casing 2 as an inclined wall that is inclined downward from the front to the rear.

The paper 3 sent from the transport roller 70 is discharged forward by the paper discharge roller 72 after the transport direction is reversed in the paper discharge path 71. The discharged paper 3 is placed on the paper discharge tray 73.
(Description of the scanner unit)
In such a color laser printer 1, in the scanner unit 12, the two laser irradiation optical units 18 arranged to face each other with the polygon mirror 17 interposed therebetween are arranged orthogonal to each other and spaced apart from each other in the sub-scanning direction Y. The two laser beams emitted from the two laser emitting units 24 are converted into parallel light beams by the two collimating lenses 25, respectively, and then the two first slits of the first slit plate 26 are used. Each stray light is prevented by passing through 30 respectively.

Thereafter, the two laser beams are linearly transmitted through the reflection mirror 27, while the other laser beam is reflected by approximately 90 ° and refracted at a substantially right angle, and the optical paths of the two laser beams are The images are combined so as to coincide with each other in the main scanning direction X while being spaced apart in the sub-scanning direction Y.
Then, the two laser beams combined in the optical path pass through the two second slits 31 arranged in parallel in the sub-scanning direction Y of the second slit plate 28, and at this time, the two laser beams are The positions are adjusted with respect to each other in the scanning direction Y. Thereby, even if two laser beams whose main scanning directions X coincide with each other by the reflecting mirror 27 cause an error in the sub-scanning direction Y due to processing accuracy of the reflecting mirror 27 or position accuracy of the collimating optical system. The error is adjusted.

Thereafter, the two laser beams respectively passing through the two second slits 31 are refracted so as to converge in the sub-scanning direction Y by one cylindrical lens 29, and thereafter enter the polygon mirror 17 at different angles, respectively. The
As described above, the errors of the two laser beams incident on the polygon mirror 17 are reduced not only in the main scanning direction X but also in the sub-scanning direction Y by the two second slits 31 of the second slit plate 28. Therefore, the polygon mirror 17 can deflect and scan the four laser beams incident from the two laser irradiation optical units 18 with high accuracy.

  In addition, in each laser irradiation optical unit 18, each second slit 31 through which each laser beam passes is provided in the same second slit plate 28, so that the relative position accuracy between each laser beam is high, and the polygon A precise relative position of each laser beam incident on the mirror 17 can be ensured. Therefore, the polygon mirror 17 can ensure accurate deflection and scanning between the laser beams.

  Further, the second slit plate 28 is slidably guided by the two slide rods 33 of the guide member 32, and is positioned by each slide rod 33 and the bottom wall 43. Therefore, the second slit plate 28 can be positioned with high accuracy, and the respective second slits 31 arranged in the second slit plate 28 can be arranged with high accuracy. Therefore, it is possible to achieve more accurate deflection and scanning of each laser beam.

  In the scanner unit 12, in each laser irradiation optical unit 18, two first slits 30 are opposed to the two collimating lenses 25 between the two laser light emitting units 24 and the reflection mirror 27. A first slit plate 26 is provided. The two first slits 30 of the first slit plate 26 limit the cross-sectional shapes of the two laser beams. Therefore, it is possible to reliably prevent the laser light emitted from one laser light emitting unit 24 from interfering with the laser light emitted from the other laser light emitting unit 24. As a result, the two first slits 30 of the first slit plate 26 can prevent the stray light of the laser light emitted from the two laser light emitting units 24, respectively.

  Moreover, in each laser irradiation optical part 18, the laser light emission part 24 is arrange | positioned as 1 set of 2 pieces, and the 2nd slit board 28 is provided 1 piece | piece with respect to 1 set of 2 pieces, and it is 2nd slit. 31 is formed corresponding to each set of two laser light emitting portions 24. As a result, the four laser light emitting sections 24 are divided into two groups and arranged in the two laser irradiation optical sections 18, so that an efficient layout can be ensured and accurate deflection and scanning of each laser beam can be performed. Can be achieved.

  In the scanner unit 12, the two laser irradiation optical units 18 are arranged on opposite sides so as to be symmetric with respect to the polygon mirror 17. That is, in each laser irradiation optical unit 18, the laser light emitting units 24 provided as a set of two are arranged on opposite sides so as to be symmetric with respect to the polygon mirror 17. In addition, the fθ lens 19 is configured so that two sets of laser beams are polygon mirrors so as to correspond to two sets of laser beams emitted from two laser irradiation optical units 18, that is, two sets of laser emission units 24. Two are provided so as to face each other across the polygon mirror 17 in a direction orthogonal to the direction of incidence with respect to 17. Then, a set of two laser beams that have passed through the two fθ lenses 19, that is, four laser beams, are respectively the optical paths that are independent of each other, that is, the yellow optical unit 20Y, the magenta optical unit 20M, the cyan optical unit 20C, and The light passes through the black optical unit 20K and is emitted from the yellow exit window 21Y, the magenta exit window 21M, the cyan exit window 21C, and the black exit window 21K.

  As a result, two sets of four laser beams emitted from two sets of laser light emitting units 24 arranged symmetrically as one set with respect to the polygon mirror 17 are irradiated to the polygon mirror 17 from the symmetrical direction, and are deflected and After scanning in the main scanning direction X, the light passes through the two fθ lenses 19 and is converted into a light beam having a constant velocity on the image plane. The two sets of four laser beams are emitted from different emission windows 21 by the respective laser emission optical units 20. Therefore, the scanner unit 12 can be configured in a compact manner, and the four laser beams deflected and scanned with high accuracy can be emitted from the different emission windows 21.

In this color laser printer 1, four process units 13 are provided corresponding to the laser beams emitted from the four emission windows 21 of the scanner unit 12 described above, and the four process units 13 provided in each process unit 13 are provided. An electrostatic latent image is formed on the photosensitive drum 51 by irradiating each independent laser beam.
The four electrostatic latent images formed on the four photosensitive drums 51 are respectively developed by the four developing rollers 56 provided in the respective process units 13 to correspond to yellow, magenta, cyan, and black colors. In the transfer unit 14, the color is sequentially superimposed on the same paper 3.

For this reason, in this laser printer 1, an accurate electrostatic latent image can be formed on each photosensitive drum 51 to achieve accurate color image formation, while at the same speed as a monochrome image. Can be formed.
In the above description, the two second slits 31 formed in the second slit plate 28 may be the same in both the opening shape and the opening area. The color can be changed as appropriate according to the color to be developed.

Further, the interval between the two second slits 31 in the sub-scanning direction Y is also appropriately determined according to the type of the laser light emitting unit 24 and the color to be developed.
Further, in the above description, two laser irradiation optical units 18 each including a set of two laser emission units 24 are arranged symmetrically with respect to the polygon mirror 17, but the arrangement of each laser emission unit 24 is particularly limited. Alternatively, for example, one laser irradiation optical unit 18 including a set of four laser light emitting units 24 may be arranged on one side with respect to the polygon mirror 17.

  In such an arrangement, four second slits 31 are opened in the second slit plate 28 in parallel in the sub-scanning direction Y with a space therebetween.

1 is a side sectional view showing an embodiment of a color laser printer as an image forming apparatus of the present invention. FIG. 2 is a side view showing an optical system of a laser irradiation optical unit in the scanner unit of the color laser printer shown in FIG. 1. FIG. 2 is a plan view showing an optical system of a laser irradiation optical unit in the scanner unit of the color laser printer shown in FIG. 1. FIG. 2 is a perspective view showing an optical system of a laser irradiation optical unit in the scanner unit of the color laser printer shown in FIG. 1. FIG. 5 is a perspective view for explaining positioning of a second slit plate in the laser irradiation optical unit shown in FIG. 4. FIG. 2 is a side view showing an optical system of a laser emission optical unit in the scanner unit of the color laser printer shown in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Color laser printer 15 Photosensitive drum 17 Polygon mirror 19 f (theta) lens 20 Laser emission optical part 24 Laser light emission part 26 1st slit board 27 Reflecting mirror 28 2nd slit board 31 2nd slit 32 Guide member 51 Photosensitive drum 56 Developing roller

Claims (9)

A plurality of laser light emitting sections for emitting laser light;
A light deflecting means for deflecting and scanning the laser light emitted from the plurality of laser light emitting sections in the main scanning direction;
An optical path synthesizing unit that is arranged between the plurality of laser light emitting units and the light deflecting unit in the laser beam passing direction and matches the plurality of laser beams emitted from the plurality of laser light emitting units in the main scanning direction. When,
An aperture hole disposed between the optical path combining unit and the optical deflecting unit in the laser beam passing direction and formed corresponding to the plurality of laser beams emitted from the plurality of laser emission units is sub-scanning. A scanner device comprising: a slit member arranged side by side in a direction.   The scanner device according to claim 1, further comprising a guide member for slidably guiding the slit member to position the slit member.   Stray light of the laser light provided corresponding to the plurality of laser light emitting units and disposed between each laser light emitting unit and the optical path combining means in the laser light passing direction and emitted from each laser light emitting unit The scanner device according to claim 1, further comprising stray light preventing means for preventing the light from being lost.   The scanner device according to claim 3, wherein the stray light preventing unit restricts a cross-sectional shape of the laser beam toward the optical path combining unit. The laser emission unit is arranged as a plurality of sets,
One slit member is provided for each group,
The scanner device according to any one of claims 1 to 4, wherein the aperture holes are respectively formed corresponding to the laser light emitting units of each set. The plurality of laser light emitting units are arranged symmetrically as a set of two with respect to the light deflection means,
Two light beams are provided corresponding to each set of laser beams that are emitted from each set of the laser light emitting units and deflected and scanned by the light deflecting unit, and each set of laser beams has a constant velocity on the image plane. An fθ lens that converts to
6. The scanner device according to claim 1, further comprising: optical path forming means for emitting each laser beam that has passed through each fθ lens from a different position. A scanner device according to any one of claims 1 to 6;
An image comprising: a plurality of photoconductors each irradiated with a plurality of laser beams deflected and scanned in the main scanning direction by the light deflecting unit, and forming an electrostatic latent image by the irradiation. Forming equipment. A plurality of laser light emitting sections for emitting laser light;
A light deflecting means for deflecting and scanning the laser light emitted from the plurality of laser light emitting sections in the main scanning direction;
An optical path synthesizing unit that is arranged between the plurality of laser light emitting units and the light deflecting unit in the laser beam passing direction and matches the plurality of laser beams emitted from the plurality of laser light emitting units in the main scanning direction. When,
An aperture hole disposed between the optical path combining unit and the optical deflecting unit in the laser beam passing direction and formed corresponding to the plurality of laser beams emitted from the plurality of laser emission units is sub-scanning. A slit member arranged side by side in the direction;
An image comprising: a plurality of photoconductors each irradiated with a plurality of laser beams deflected and scanned in the main scanning direction by the light deflecting unit, and forming an electrostatic latent image by the irradiation. Forming equipment. Four photoreceptors are provided,
9. The image according to claim 7, further comprising developer supply means that is provided corresponding to each of the photoconductors and supplies developer of different colors to the photoconductors. Forming equipment.

Images