JP4529677B2 - Optical scanning apparatus and image forming apparatus - Google Patents

Description

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

In an electrophotographic image forming apparatus such as a laser printer, an electrostatic latent image formed on a photosensitive drum is developed with toner to form a toner image, which is transferred to a sheet to form an image. .
Such an image forming apparatus is equipped with an optical scanning device for forming an electrostatic latent image on a photosensitive drum. In an optical scanning device, laser light emitted from a laser diode is collimated into a parallel light beam by a collimating lens, and after the spread of the light beam is regulated through a slit, it is focused in the sub-scanning direction by a cylindrical lens and rotated at high speed. The image is formed on a polygon mirror. The light beam reflected by the polygon mirror is scanned in the main scanning direction, and is emitted from the optical scanning device toward the photosensitive drum via various lenses and mirrors.

In such an optical scanning device, if the starting point of the light beam, that is, the laser diode and the collimating lens are not aligned with high accuracy, the optical path shift thereafter increases.
Therefore, for example, a laser diode is placed at the point of action of the holding part with the connecting part as a fulcrum and the extended end as a force point, and the screw is adjusted at the force point to finely adjust the distance between the laser diode and the collimating lens. It has been proposed to do.
JP 2004-163463 A

However, a tandem type color laser printer is known in which four photosensitive drums on which electrostatic latent images of respective colors are formed are provided corresponding to yellow, magenta, cyan, and black.
In such a tandem type color laser printer, an electrostatic latent image corresponding to each color is formed on each of the four photosensitive drums, so that four laser diodes and collimating lenses are provided corresponding to the four photosensitive drums. Necessary. Therefore, four holding parts for holding the laser diode and the collimating lens as described in Patent Document 1 so as to be position-adjustable are also required.

However, if such a holding portion is provided corresponding to each laser diode and collimating lens, the device configuration becomes complicated and the cost increases.
Further, in each holding portion, it is necessary to adjust the position between each laser diode and the collimating lens with high accuracy.
An object of the present invention is to efficiently arrange the first laser light emitting unit and the first lens, and the second laser light emitting unit and the second lens, so that the configuration can be simplified and the cost can be reduced. In addition, an optical scanning device capable of easily achieving positional adjustment between the first laser light emitting unit and the first lens and between the second laser light emitting unit and the second lens, and the optical scanning device therefor The present invention provides an image forming apparatus.

In order to achieve the above object, the invention described in claim 1 is an optical scanning device, wherein a first holding part that holds a first laser emitting part that emits first laser light and a first screw are inserted. A first holding member having a first screw insertion portion, a second holding portion for holding a second laser light emitting portion for emitting a second laser beam, and a second screw insertion portion for inserting a second screw. 2 holding members, a first lens support that supports the first lens through which the first laser light passes, a second lens support that supports the second lens through which the second laser light passes, and the first A first screw insertion fixing portion that is inserted to fix the first screw inserted through the screw insertion portion, and a second screw that is inserted to fix the second screw inserted through the second screw insertion portion. A base member including an insertion fixing portion, the first laser beam, and the second laser beam. And a light deflector for deflecting and scanning the laser light in the main scanning direction, the first holding member, the second holding member and the base member, by folding a sheet metal, are formed continuously, The first screw insertion portion and the first screw insertion fixing portion are spaced apart from each other, and the first holding member and the first lens support portion are the first screw insertion portion and the first screw insertion portion. A distance between the first holding member and the first lens support portion is arranged in a direction opposite to the one screw insertion fixing portion, and is spaced from the first screw insertion and fixing portion with respect to the first screw insertion fixing portion. The second screw insertion portion and the second screw insertion fixing portion are spaced apart from each other, and the second holding member and the second lens support portion are the second screw insertion portion. Part and the second screw insertion fixing part Characterized in direction, they are arranged at intervals, by advancing and retracting with respect to the second screw insertion fixing portion of the second screw, that the gap between the second holding member and the second lens support portion is adjusted It is said.

  According to such a configuration, the first laser emission unit is held by the first holding unit provided on the first holding member, and the second laser emission unit is held by the second holding unit provided on the second holding member. The first lens and the second lens are supported by the first lens support portion and the second lens support portion provided on the base member, respectively, so that the first laser light emission portion and the first lens, and the second laser light emission. The part and the second lens can be efficiently arranged to simplify the configuration and reduce the cost.

  In addition, after the first screw is inserted into the first screw insertion portion provided in the first holding member, the first screw is fixed by adjusting the position to the first screw insertion fixing portion provided in the base member. It is possible to adjust the position of the first laser emitting unit with respect to the first lens by adjusting the relative arrangement of the first member and the base member. Further, after the second screw is inserted into the second screw insertion portion provided in the second holding member, the second holding member is adjusted in position and fixed to the second screw insertion fixing portion provided in the base member. It is possible to adjust the position of the second laser light emitting unit with respect to the second lens by adjusting the relative arrangement of the base member and the base member. Therefore, position adjustment between the first laser light emitting unit and the first lens and between the second laser light emitting unit and the second lens can be easily achieved.

Further, according to the configuration of this, the first holding member, the second holding member and the base member, because it is formed continuously, it is possible to form these integrally. Therefore, the number of parts can be reduced and the configuration can be simplified.

Further, according to the configuration as this, by bending sheet metal, the first holding member, since the second holding member and the base member are continuously formed, be simplified and cost reduction of the structure it can.

  According to such a structure, if the 1st screw penetrated by the 1st screw insertion part is advanced / retreated with respect to the 1st screw insertion fixing part, opposition of a 1st screw insertion part and a 1st screw insertion fixing part By adjusting the relative positions of the first holding member and the first lens support portion that are spaced from each other in the direction, it is possible to achieve an accurate position adjustment of the first laser light emitting unit with respect to the first lens. Moreover, if the 2nd screw penetrated by the 2nd screw insertion part is advanced / retreated with respect to the 2nd screw insertion fixing | fixed part, it will space apart in the opposing direction of a 2nd screw insertion part and a 2nd screw insertion fixing | fixed part. By adjusting the relative positions of the second holding member and the second lens support portion that are arranged in this manner, it is possible to achieve an accurate position adjustment of the second laser light emitting portion with respect to the second lens.

According to a second aspect of the present invention, in the first aspect of the invention, the first lens support portion and the second lens support portion are arranged at different positions in the sub-scanning direction, and the first Main scanning of the first laser light and the second laser light is performed by reflecting at least one of the first laser light that has passed through the lens support portion and the second laser light that has passed through the second lens support portion. A light reflecting means for matching the relative positions in the directions is provided.

  According to such a configuration, since the relative positions of the first laser beam and the second laser beam in the main scanning direction are made to coincide with each other by the light reflecting means, the first lens support unit and the second lens support unit are moved in the sub-scanning direction. Can be arranged at positions different from each other in order to ensure an efficient layout of the first laser light emitting unit and the first lens, and the second laser light emitting unit and the second lens, thereby reducing the size of the apparatus. it can.

According to a third aspect of the present invention, in the second aspect of the present invention, between the first lens support portion and the light reflecting means in the optical path of the first laser light, and the second laser light. In the optical path, a slit member having a slit is provided between the second lens support portion and the light reflecting means.
According to such a configuration, the first laser light that has passed through the first lens supported by the first lens support portion enters the light reflecting means after passing through the slit. The first laser light after passing through the slit is prevented from interfering with the second laser light because the sectional shape is limited by the slit. The second laser light that has passed through the second lens supported by the second lens support portion enters the light reflecting means after passing through the slit. Since the cross-sectional shape of the second laser light after passing through the slit is limited by the slit, interference with the first laser light is prevented. For this reason, mutual interference between the first laser beam and the second laser beam is prevented, and the relative positions of the first laser beam and the second laser beam in the main scanning direction can be accurately matched by the light reflecting means. Can do.

According to a fourth aspect of the present invention, in the third aspect of the invention, there is provided positioning means for positioning the light reflecting means, and the slit member is formed integrally with the positioning means. It is characterized by that.
According to such a configuration, since the slit member is formed integrally with the positioning means, the number of parts can be reduced and the configuration can be simplified.

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects of the present invention, the base member includes a sub-portion between the first lens support portion and the second lens support portion. A stepped portion in the scanning direction is provided.
According to such a configuration, the first lens support portion and the second lens support portion are moved in the sub-scanning direction by the step portion provided in the sub-scanning direction between the first lens support portion and the second lens support portion. They can be easily arranged at different positions.

The invention according to claim 6 is the invention according to any one of claims 1 to 5 , wherein the first holding member and the second holding member are arranged in a substantially perpendicular direction. It is characterized by.
According to such a configuration, since the first holding member and the second holding member are arranged in a direction substantially perpendicular to each other, the first laser light emitting unit held by the first holding unit of the first holding member; The second laser light emitting part held by the second holding part of the second holding member is arranged in a substantially perpendicular direction to each other, and the light reflecting means makes the first laser light and the second laser light relative to each other in the main scanning direction. The positions can be matched with high accuracy. Further, an efficient layout of the first laser light emitting unit and the second laser light emitting unit can be ensured, and the apparatus can be miniaturized.

The invention according to claim 7 is the invention according to any one of claims 1 to 6 , wherein the base member is supported by the first screw insertion fixing portion and the second screw insertion fixing portion. The first screw insertion fixing portion and the second screw insertion fixing portion are formed by being bent in opposite directions from the support member.

According to such a configuration, the first screw insertion fixing portion and the second screw insertion fixing portion are bent in opposite directions from the support member, so that the first screw insertion fixing portion and the second screw insertion fixing portion and the second screw can be easily bent. The screw insertion fixing portions can be individually arranged.
The invention according to claim 8 is the optical system according to any one of claims 1 to 7 , wherein the first holding member, the second holding member, and the base member are used as a set of optical elements. The optical deflector includes a plurality of deflecting surfaces, and the first laser light and the second laser light emitted from the optical elements are different for each of the optical elements. A different deflecting surface of the deflecting means is irradiated.

According to such a configuration, the first laser beam and the second laser beam emitted from each of the optical elements are irradiated to the different deflection surfaces of the light deflecting unit for each different optical element. Since it is arranged, an efficient layout can be secured and the device can be miniaturized.
The invention described in claim 9 is the invention described in claim 8 , characterized in that the optical element is provided in two.

According to such a configuration, since the two optical elements are provided, the four laser beams emitted from the four laser emission units can be scanned by the light deflecting unit. Therefore, it can be preferably used to form a color image by forming an electrostatic latent image corresponding to each of yellow, magenta, cyan and black.
According to a tenth aspect of the present invention, in the ninth aspect of the invention, the first laser light and the second laser light emitted from one of the optical elements and the other optical element emits light. The optical elements are arranged such that the first laser light and the second laser light are incident on the light deflecting means in parallel.

According to such a configuration, each of the first laser beam and the second laser beam and the other first laser beam and the second laser beam are incident on the optical deflecting unit in parallel. Since the optical elements are arranged, each optical element can be arranged compactly with respect to the light deflection means.
An eleventh aspect of the invention is an image forming apparatus, wherein the optical scanning device according to any one of the first to tenth aspects and the first laser beam scanned in the main scanning direction by the optical deflection unit. And a plurality of photoconductors that are respectively provided to the respective laser beams of the second laser beam, are irradiated with the respective laser beams, and electrostatic latent images are formed by the irradiation.

According to such a configuration, an electrostatic latent image is formed on each photoconductor by the first laser beam and the second laser beam emitted from the optical scanning device. Therefore, it is possible to form an accurate electrostatic latent image on each photoconductor to achieve an accurate multicolor image.
A twelfth aspect of the invention is an image forming apparatus, wherein the optical scanning device according to the ninth or tenth aspect and two sets of first laser beams scanned in the main scanning direction by the light deflecting unit. And four photoconductors that are respectively provided to the respective laser beams of the second laser beam and are irradiated with the respective laser beams, and electrostatic latent images are respectively formed by the irradiation, and are formed on the respective photoconductors. The electrostatic latent images thus developed are developed in different colors.

  According to such a configuration, the electrostatic latent images respectively formed on the four photoconductors are developed with different colors. 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, the first laser emission unit and the first lens, and the second laser emission unit and the second lens are efficiently arranged to simplify the configuration and reduce the cost. Can be achieved. Further, it is possible to easily achieve position adjustment between the first laser light emitting unit and the first lens and between the second laser light emitting unit and the second lens.
Further , the number of parts can be reduced and the configuration can be simplified.

In addition , the configuration can be simplified and the cost can be reduced.
In addition , it is possible to achieve accurate position adjustment of the first laser light emitting unit with respect to the first lens and the second laser light emitting unit with respect to the second lens.
According to the second aspect of the present invention, an efficient layout of the first laser light emitting unit and the first lens, and the second laser light emitting unit and the second lens can be ensured, and the apparatus can be miniaturized. be able to.

According to the third aspect of the present invention, since the mutual interference between the first laser beam and the second laser beam is prevented, the light reflecting means in the main scanning direction of the first laser beam and the second laser beam. The relative positions can be matched with high accuracy.
According to the invention described in claim 4 , the number of parts can be reduced and the configuration can be simplified.

According to the fifth aspect of the present invention, the first lens support portion and the second lens support portion can be easily arranged at different positions in the sub-scanning direction.
According to the sixth aspect of the present invention, the relative positions of the first laser beam and the second laser beam in the main scanning direction can be made to coincide with each other with high accuracy by the light reflecting means. Further, an efficient layout of the first laser light emitting unit and the second laser light emitting unit can be ensured, and the apparatus can be miniaturized.

According to the seventh aspect of the present invention, the first screw insertion fixing portion and the second screw insertion fixing portion can be individually arranged by simple bending.
According to the eighth aspect of the invention, an efficient layout can be ensured and the apparatus can be downsized.
According to the ninth aspect of the present invention, it can be suitably used for forming a color image.

According to the invention described in claim 10 , each optical element can be arranged compactly with respect to the light deflection means.
According to the eleventh aspect of the present invention, it is possible to form an accurate electrostatic latent image on each photoconductor, thereby achieving an accurate multicolor image formation.
According to the twelfth aspect of the present invention, if the developer images formed on the respective photoconductors are sequentially color-superposed, a color image can be formed at substantially the same speed as a monochrome image.

(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 81, it is formed as a substantially U-shaped conveyance path for the sheet 3 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 fed toward
(Configuration of image forming unit)
The image forming unit 5 includes a scanner unit 12 as an optical scanning 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. 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. Laser for deflecting and scanning the laser light deflected and scanned by the irradiation optical unit 18 and the polygon mirror 17 into a parallel light beam having a constant velocity, and a laser for emitting the laser light having passed through the fθ lens 19 as laser light corresponding to each color. And an output optical unit 20.

  As shown in FIG. 6, the scanner casing 16 has a box shape, and the exit wall 21 corresponding to each color is formed on the bottom wall 62. The respective emission windows 21 are provided at different positions in the front-rear direction and spaced from each other, and sequentially correspond to the respective colors from the front to the rear in order of the yellow emission window 21Y, the magenta emission window 21M, and the cyan emission window. 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 two first laser light emitting units 25a and two second laser light emitting units 25b described later. Yes. The polygon mirror 17 is formed in a polyhedron (for example, a hexahedron) having a plurality of deflection surfaces, and the power of the scanner motor housed in the motor substrate 22 around the rotation shaft 23 provided at the center thereof. Is driven to rotate at high speed.

The motor substrate 22 is fixed to the bottom wall 62 of the scanner casing 16 via a boss (not shown).
As shown in FIG. 2, the laser irradiation optical unit 18 has a width direction (a direction perpendicular to the front-rear direction and the up-down direction of the color laser printer 1) with respect to the polygon mirror 17. "Directions" all refer to the width direction of the laser printer 1.) Two are provided on one side.

  Each laser emission unit 18 is supported by a position adjustment frame 24 as an optical element, a first laser emission unit 25 a and a second laser emission unit 25 b held by the position adjustment frame 24, and the position adjustment frame 24. A set of a first collimating lens 26a as a first lens and a second collimating lens 26b as a second lens, a slit plate 27 as a slit member, a reflecting mirror 28 as a light reflecting means, and a cylindrical lens 29 As prepared.

  As shown in FIGS. 4 and 5, the position adjustment frame 24 is formed by bending one sheet metal. More specifically, the position adjustment frame 24 serves as a first holder plate 30 as a first holding member that holds the first laser light emitting portion 24a and a second holding member that holds the second laser light emitting portion 25b. A second holder plate 31 and a base plate 32 as a base member for supporting the first collimating lens 26a and the second collimating lens 26b are continuously and integrally provided.

The base plate 32 is integrally provided with a fixed plate 33 as a support member fixed to a boss (not shown) of the scanner casing 16, a support plate 34 that supports the first collimating lens 26a, and a connecting rod 39.
The fixed plate 33 is a flat plate having a substantially rectangular shape in plan view, and the second lens groove 35 as a second lens support portion for supporting the second collimating lens 26 b and the fixed plate 33 are formed on the bottom wall 62 of the scanner casing 16. A fixing hole 36 for fixing, a first screw fixing plate 37 as a first screw insertion fixing portion for fixing the first screw 52 (see FIG. 3), and a second screw 57 (see FIG. 3) are fixed. And a second screw fixing plate 38 as a second screw insertion fixing portion.

The second lens groove 35 is formed at the inner end in the width direction of the fixed plate 33 so that the fixed plate 33 is bent into a substantially V-shaped cross section along the front-rear direction.
Two fixing holes 36 are formed at one end in the front-rear direction of the fixing plate 33 and spaced apart from each other in the width direction. Each fixing hole 36 is formed so as to penetrate the thickness direction of the fixing plate 33.

The first screw fixing plate 37 is formed of a substantially rectangular flat plate extending in the up-down direction, and is formed by bending the outer edge of the fixing plate 33 in a substantially perpendicular direction from the end edge of the fixing plate 33. Yes. The first screw fixing plate 37 is formed with a first screwing hole 42 having a circular cross section through which a first screw 52 (to be described later) is screwed at the center thereof so as to penetrate the thickness direction.
The second screw fixing plate 38 is formed of a substantially rectangular flat plate extending in the up-down direction, and is formed by being bent substantially vertically upward from the end edge of the fixing plate 33 at one end edge in the front-rear direction of the fixing plate 33. ing. In the second screw fixing plate 38, a second screwing hole 43 having a circular cross section into which a later-described second screw 57 is screwed is formed at the center thereof so as to penetrate the thickness direction.

Thus, the first screw fixing plate 37 and the second screw fixing plate 38 are arranged in a substantially perpendicular direction to each other in plan view, and are bent in directions opposite to each other with respect to the fixing plate 33.
The support plate 34 is disposed on the other side in the front-rear direction with respect to the fixed plate 33 and is provided so as to be continuous with the fixed plate 33 via a connecting rod 39.

The support plate 34 is formed of a flat plate having a substantially rectangular shape in plan view, the width direction outer edge of which is flush with the width direction outer edge of the fixed plate 33 in the width direction, and a first plate for supporting the first collimating lens 26a. A first lens groove 40 is formed as a single lens support.
The first lens groove 40 is formed at the center in the front-rear direction of the support plate 34 such that the support plate 34 is bent into a substantially V-shaped cross section along the width direction.

Two connecting rods 39 are provided along the vertical direction at intervals in the width direction. Each connecting rod 39 is formed such that an upper end portion thereof is bent from the other end portion in the front-rear direction of the fixing plate 34 toward the lower side in a substantially perpendicular direction, and a lower end portion thereof is formed in the front-rear direction of the support plate 34. It is formed so as to be bent from the one side end portion upward in a substantially perpendicular direction.
Thus, a step portion 41 is formed between the support plate 34 and the fixed plate 33, in which the support plate 34 is disposed above and the fixed plate 33 is disposed below.

  The first holder plate 30 is substantially L-shaped in plan view, and integrally includes a first short plate 44 and a first holding plate 45 that are continuous with each other in a substantially right-angle direction and a first holding portion and a first screw insertion portion. The first short plate 44 is supported at the other side edge in the front-rear direction of the support plate 34 so that the lower end edge of the first short plate 44 and the other side edge in the front-rear direction of the support plate 34 are continuous. It is formed so as to be bent from the edge of the plate 34 upward in a substantially right angle direction.

In addition, the first long plate 45 is spaced from the outer edge in the width direction of the first short plate 44 so that the free end portion in the front-rear direction is opposed to the first screw fixing plate 37 with a gap in the width direction. It is formed so as to be bent in a substantially perpendicular direction toward one side in the front-rear direction. Thus, the middle of the first long plate 45 in the front-rear direction is opposed to the first lens groove 40 with a gap in the width direction.
In the first long plate 45, a first holding hole 46 having a circular cross section for holding the first laser light emitting portion 25a passes through the thickness direction at a position facing the first lens groove 40 in the width direction. Is formed. In addition, the first long plate 45 has a first insertion hole 47 having a circular cross section through which a first screw 52 (described later) is inserted at a position facing the first screw hole 42 in the width direction. It is formed to penetrate.

  The second holder plate 31 is substantially L-shaped in plan view, and integrally includes a second short plate 48 that is continuous with each other in a substantially perpendicular direction, and a second long plate 49 as a second holding portion and a second screw insertion portion. The second short plate 48 is made of a flat plate at the inner edge in the width direction of the fixing plate 33 so that the lower end edge of the second short plate 48 and the inner edge in the width direction of the fixing plate 33 are continuous. It is formed so as to be bent substantially upward in the direction perpendicular to the edge.

Further, the second long plate 49 has one end edge in the front-rear direction of the second short plate 48 such that the free end portion in the width direction is opposed to the second screw fixing plate 38 with a space in the front-rear direction. From the outside, it is formed so as to be bent in a substantially perpendicular direction toward the outside in the width direction. As a result, the middle of the second long plate 49 in the width direction is opposed to the second lens groove 35 with a gap in the front-rear direction.
In the second long plate 49, a second holding hole 50 having a circular cross section for holding the second laser light emitting portion 25b passes through the thickness direction at a position facing the second lens groove 35 in the front-rear direction. Is formed. In addition, the second long plate 49 has a circular second insertion hole 51 through which a second screw 57 described later is inserted at a position facing the second screwing hole 43 in the front-rear direction in the thickness direction. It is formed to penetrate.

Accordingly, the first long plate 45 of the first holder plate 30 and the second long plate 49 of the second holder plate 31 are arranged in a substantially perpendicular direction to each other in plan view.
As shown in FIG. 3, the first laser light emitting unit 25a is made of a semiconductor laser or the like, and is mounted in the first holding hole 46 so that the first laser light can be emitted inward in the width direction.
The second laser light emitting portion 25b is made of a semiconductor laser or the like, and is attached to the second holding hole 50 so that the second laser light can be emitted toward the other side in the front-rear direction.

As shown in FIG. 2, the first collimating lens 26 a is installed in the first lens groove 40 at a distance in the width direction with respect to the first laser light emitting unit 25 a. As a result, the first laser light emitting portion 25a and the first collimating lens 26a are arranged to face each other with an interval in the width direction.
The second collimating lens 26b is disposed in the second lens groove 35 with a space in the front-rear direction with respect to the first laser light emitting unit 25b. As a result, the second laser light emitting unit 25b and the second collimating lens 26b are disposed to face each other with a gap in the front-rear direction.

And the relative position between the 1st laser light emission part 25a and the 1st collimating lens 26a is adjusted as follows.
That is, as shown in FIG. 5, first, the first screw 52 is inserted into the first insertion hole 47 from the outside in the width direction, and then screwed into the first screw hole 42. Thereafter, the first screw 52 is screwed or unscrewed with respect to the first screw hole 42. The head of the first screw 52 has a larger diameter than the first insertion hole 47.

  If the first screw 52 is screwed into the first screw hole 42, the first long plate 45 has a connecting portion with the first short plate 44 (a bent portion of the first holder plate 30) as a fulcrum. The free end portion on the opposite side bends inward in the width direction and approaches the first screw fixing plate 37. Then, the first laser light emitting portion 25a attached to the first long plate 45 is close to the first collimating lens 26a installed in the first lens groove 40, and the first laser light emitting portion 25a and the first collimating lens 25a. The relative distance to the lens 26a is shortened.

  On the other hand, if the first screw 52 is screwed out with respect to the first screw hole 42, the first long plate 45 has a free end portion on the outer side in the width direction with the connecting portion with the first short plate 44 as a fulcrum. And is separated from the first screw fixing plate 37. Then, the first laser light emitting unit 25a attached to the first long plate 45 is separated from the first collimating lens 26a installed in the first lens groove 40, and the first laser light emitting unit 25a and the first collimating member are separated. The relative distance between the lens 26a is increased.

Then, by adjusting the relative distance between the first laser light emitting portion 25a and the first collimating lens 26a by such screwing or screwing of the first screw 52 with respect to the first screwing hole 42, the first laser light emission is achieved. The relative position between the portion 25a and the first collimating lens 26a is adjusted.
Further, the relative positions of the second laser light emitting unit 25b and the second collimating lens 26b are adjusted as follows.

That is, first, the second screw 57 is inserted into the second insertion hole 51 from one side in the front-rear direction, and then screwed into the second screw hole 43. Thereafter, the second screw 57 is screwed or screwed with respect to the second screw hole 43. The head of the second screw 57 has a larger diameter than the second insertion hole 43.
If the second screw 57 is screwed into the second screw hole 43, the second long plate 49 has a connecting portion with the second short plate 48 (a bent portion of the second holder plate 31) as a fulcrum. The free end portion on the opposite side bends toward the other side in the front-rear direction and approaches the second screw fixing plate 38. Then, the second laser light emitting portion 25b attached to the second long plate 49 is close to the second collimating lens 26b installed in the second lens groove 35, and the second laser light emitting portion 25b and the second collimating lens are arranged. The relative distance to the lens 26b is shortened.

  On the other hand, if the second screw 57 is screwed out with respect to the second screwing hole 43, the second long plate 49 has a free end portion in the front-rear direction with the connecting portion with the second short plate 48 as a fulcrum. Bends away from the second screw fixing plate 38. Then, the second laser light emitting unit 25b mounted on the second long plate 49 is separated from the second collimating lens 26b installed in the second lens groove 35, and the second laser light emitting unit 25b and the second collimating member are separated. The relative distance between the lens 26b is increased.

Then, by adjusting the relative distance between the second laser light emitting portion 25b and the second collimating lens 26b by such advancement or retraction of the second screw 57 with respect to the second screw hole 43, the second laser light emission is achieved. The relative position between the portion 25b and the second collimating lens 26b is adjusted.
As shown in FIG. 2, the position adjustment frame 24 provided with the first laser light emitting unit 25a and the second laser light emitting unit 25b and the first collimating lens 26a and the second collimating lens 26b as shown in FIG. Two polygon mirrors 17 are arranged adjacent to each other on one side in the width direction. Each position adjustment frame 24 is one set of laser light composed of the first laser light and the second laser light emitted from the first laser light emission unit 25a and the second laser light emission unit 25b of the one position adjustment frame 24, respectively. And the other set of laser light composed of the first laser light and the second laser light emitted from the first laser light emitting unit 25a and the second laser light emitting unit 25b of the other position adjusting frame 24, respectively, One set of laser light and the other set of laser light are incident on the polygon mirror 17 in parallel after passing through the reflection mirror 28 and the cylindrical lens 29, as will be described later. Has been placed.

More specifically, as shown in FIG. 3, the two position adjustment frames 24 are configured such that the support plates 34 face each other in the front-rear direction and the first short plates 44 are opposed to each other in the front-rear direction. Adjacent to each other along the front-rear direction.
Further, in each position adjustment frame 24 arranged in this way, the first laser light emitting portion 25a held in the first holding hole 46 and the first collimating lens 26a installed in the first lens groove 40 are second. The second laser light emitting unit 25b held in the holding hole 50 and the second collimating lens 26b installed in the second lens groove 35 are arranged at different positions in the sub-scanning direction Y (corresponding to the vertical direction). That is, in the vertical direction, the first laser light emitting unit 25a and the first collimating lens 26a are disposed on the lower side, and the second laser light emitting unit 25b and the second collimating lens 26b are disposed on the upper side.

Each position adjustment frame 24 is fixed to the bottom wall 62 of the scanner casing 16 by a fixing bolt 97 inserted into each fixing hole 36.
The slit plate 27 is installed on the bottom wall 62 of the scanner casing 16 across the two laser irradiation optical units 18. That is, the slit plate 27 is substantially U-shaped in a plan view integrally including two side plates 53 that are opposed to each other with a gap in the front-rear direction and a main plate 54 that connects the outer ends of the side plates 53 in the width direction. It is formed from a flat plate. The slit plate 27 is formed with a first slit hole 55 that opens in the front-rear direction in the main plate 54 and a second slit hole 56 that opens in each side plate 53.

Each first slit hole 55 and each second slit hole 56 are formed in a long hole shape extending in the main scanning direction X, and in the sub-scanning direction Y, each first laser light emitting unit 25a and each second laser light emitting unit. At intervals corresponding to 25b, they are spaced apart from each other.
In the slit plate 27, the second slit hole 56 opened in one side plate 53 faces the second lens groove 35 of one position adjustment frame 24 in the front-rear direction, and the second slit plate 27 opens in the other side plate 53. The two slit holes 56 face the second lens groove 35 of the other position adjustment frame 24 in the front-rear direction, and one first slit hole 55 opened in the main plate 54 is the first lens of one position adjustment frame 24. Two position adjustment frames so that the other first slit hole 55 facing the groove 40 in the width direction and opening in the main plate 54 faces the first lens groove 40 of the other position adjustment frame 24 in the width direction. 24.

More specifically, the slit plate 27 is disposed on the inner side in the width direction of the support plates 34 of the two position adjustment frames 24 and sandwiched between the fixed plates 33 in the front-rear direction.
In addition, the slit plate 27 is integrally formed with an attachment plate 61 extending inward in the opposing direction of each side plate 53 so as to bend in a substantially right angle direction from the lower end edge of each side plate 53. Is formed. Each mounting plate 61 is a substantially rectangular flat plate, and a mounting hole (not shown) is opened at the center thereof. The slit plate 27 is fixed to the bottom wall 62 of the scanner casing 16 by inserting a fixing screw 96 into the mounting hole of each mounting plate 61 and screwing the inserted fixing screw 96 to the bottom wall 62. Yes.

The slit plate 27 is integrally formed with a mirror positioning member 58 as positioning means for positioning and holding the reflecting mirrors 28.
The mirror positioning member 58 includes a top plate 60 formed so as to be bent in a substantially right-angle direction from the upper end edge so as to extend inward in the width direction from the upper end edge of the main plate 54 of the slit plate 27, and the top plate 60. A holding plate 59 is formed integrally with the inner edge of the width direction so as to be bent downward in a substantially perpendicular direction.

  The top plate 60 is formed of a flat plate having a substantially isosceles triangle shape in plan view, and the holding plate 59 is formed of a pressing plate spring, and a plurality of continuous plates are formed from the top plate 60. That is, the holding plate 59 has a central holding plate 59 that extends in the direction orthogonal to the hypotenuse from the central portion of the hypotenuse, and both ends that extend so as to be bent substantially perpendicularly downward from both ends of the hypotenuse on each hypotenuse of the top plate 60. The holding plate 59 is provided.

A mounting hole (not shown) is opened in the top plate 60, and the mirror positioning member 58 has a fixing screw 96 inserted through the mounting hole of the top plate 60, and the inserted fixing screw 96 extends from the bottom wall 62. It is fixed to the bottom wall 62 of the scanner casing 16 by being screwed to a standing boss (not shown).
The reflection mirror 28 is provided in each of the two laser irradiation optical units 18. Each reflection mirror 28 is formed of a half mirror and is disposed inside the slit plate 27. More specifically, one reflection mirror 28 is arranged to be inclined at approximately 45 ° with respect to one side plate 53 and main plate 54. The other reflecting mirror 28 is disposed so as to be inclined at approximately 45 ° with respect to the other side plate 53 and the main plate 54. Thereby, the two reflecting mirrors 28 are arranged in a substantially L shape in plan view orthogonal to each other.

Each reflecting mirror 28 is positioned and held by a holding portion 59 of a mirror positioning member 58 formed integrally with the slit plate 27. More specifically, each reflecting mirror 28 is held and positioned by a central holding plate 59 provided on each oblique side of the top plate 60 and holding plates 59 at both ends thereof.
The cylindrical lens 29 is provided in each of the two laser irradiation optical units 18. Each cylindrical lens 29 has a refractive power only in the sub-scanning direction Y, and is disposed opposite to each reflecting mirror 28 at an interval in the width direction on the inner side in the width direction of each reflecting mirror 28. It is installed on the bottom wall 62. In addition, each cylindrical lens 29 is arrange | positioned so that it may overlap along the front-back direction.

  In each laser irradiation optical unit 18, as shown in FIG. 3, the first laser beam and the second laser beam respectively emitted from the first laser light emitting unit 25a and the second laser light emitting unit 25b are respectively the first collimator. It passes through the lens 26a and the second collimating lens 26b. At this time, the first laser light and the second laser light are converted by the first collimating lens 26a and the second collimating lens 26b into parallel light beams in the main scanning direction X and the sub-scanning direction Y, respectively.

  Next, the first laser light and the second laser light that have passed through the first collimating lens 26 a and the second collimating lens 26 b pass through the first slit hole 55 and the second slit hole 56 of the slit plate 27, respectively. At this time, the first laser beam and the second laser beam are limited in cross-sectional shape orthogonal to the optical paths of the first laser beam and the second laser beam by the first slit hole 55 and the second slit hole 56, and the first laser beam Stray light of the first laser light and the second laser light emitted from the light emitting unit 25a and the second laser light emitting unit 25b, respectively, is prevented.

  Next, the first laser beam and the second laser beam that have passed through the first slit hole 55 and the second slit 56 respectively enter the reflection mirror 28 while maintaining an interval in the sub-scanning direction Y. The first laser light is incident on the lower side of the reflection mirror 28 and passes straight through the reflection mirror 28 as it is. The second laser light is incident on the upper side of the reflection mirror 28, reflected by approximately 90 °, and refracted at a substantially right angle. Thus, the optical paths of the first laser beam and the second laser beam are combined so that the relative positions in the main scanning direction X coincide.

  After that, the first laser beam and the second laser beam synthesized so that the relative positions in the main scanning direction X coincide with each other by the reflecting mirror 28 pass through the cylindrical lens 29 while maintaining an interval in the sub-scanning direction Y. To do. The first laser light and the second laser light that have passed through the cylindrical lens 29 are then refracted so as to converge in the sub-scanning direction X so as to enter the polygon mirror 17 from different angles.

Then, one set of laser light emitted from one laser irradiation optical unit 18 and the other set of laser light emitted from the other laser irradiation optical unit 18 are spaced apart from each other in the front-rear direction. However, the light is incident on the polygon mirror 17 in parallel and is incident on different deflection surfaces of the polygon mirror 17 that rotates at high speed.
As a result, the first and second laser beams are incident on the polygon mirror 17 as a set of laser beams, and the two sets of laser beams are incident on different deflection surfaces. In the set of laser beams, the first laser beam and the second laser beam are incident on the same deflection surface at different angles.

  In the polygon mirror 17, two sets of laser beams are deflected and scanned in the main scanning direction X by the high-speed rotation of the polygon mirror 17. Since the first laser beam and the second laser beam in each group are incident on the deflection surface of the polygon mirror 17 at different angles, the angles gradually separate from the deflection surface in the sub-scanning direction Y (vertical direction). (Refer to FIG. 6).

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 enters the polygon mirror 17 from each laser irradiation optical unit 18, and the first laser beam and the second laser beam scanned in the main scanning direction X by the polygon mirror 17 are converted into parallel light fluxes having a constant velocity. Convert.

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 the first laser light that has passed through the upper side of the one fθ lens 19, and the first reflecting parts 63a and 63b reflected by the reflecting mirrors 63a and 63b. And a cylindrical lens 64 that allows one laser beam to pass therethrough.

The first 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 63a in the yellow optical unit 20Y, and then reflected substantially downward in the vertical direction by the reflecting mirror 63b. Then, the light passes through the cylindrical lens 64 in the substantially vertical direction and is emitted from the yellow emission 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 65a, 65b, and 65c that reflect the second laser light that has passed through the lower side of the one fθ lens 19. And a cylindrical lens 66 that allows the second laser light reflected by the reflecting mirrors 65a, 65b, and 65c to pass therethrough.

In the magenta optical unit 20M, the second laser light that has passed through the lower side of the one fθ lens 19 is first reflected upward by the reflecting mirror 65a, then reflected backward by the reflecting mirror 65b, and then reflected by the reflecting mirror 65c. , The light passes through the cylindrical lens 66 in the substantially vertical direction and exits 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 includes three reflecting mirrors 67a, 67b, and 67c that reflect the first laser light that has passed through the upper side of the other fθ lens 19, and the reflection. And a cylindrical lens 68 that allows the first laser light reflected by the mirrors 67a, 67b, and 67c to pass therethrough.

The first laser light that has passed through the upper side of the other fθ lens 19 is first reflected upward by the reflecting mirror 67a in the cyan optical unit 20C, then reflected forward by the reflecting mirror 67b, and then reflected by the reflecting mirror 67c. After being reflected substantially downward in the vertical direction, the light passes through the cylindrical lens 68 in the substantially vertical direction and is emitted from the cyan emission window 21C.
The black optical unit 20K is disposed at the rearmost in the front-rear direction, and is reflected by the two reflecting mirrors 69a and 69b that reflect the second laser light that has passed through the lower side of the other fθ lens 19, and the reflecting mirrors 69a and 69b. And a cylindrical lens 70 that allows the second laser beam to pass therethrough.

  The second laser light that has passed through the lower side of the other fθ lens 19 passes through the reflecting mirror 69a of the cyan optical unit 20C, and is then reflected by the reflecting unit 69a obliquely forward and upward at the black optical unit 20K. After being reflected substantially downward in the vertical direction by the reflecting mirror 69b, the light passes through the cylindrical lens 70 in the substantially 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 color toners. That is, 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 71 as a photosensitive member, a scorotron charger 72, and a developing cartridge 73.
The photosensitive drum 71 has a cylindrical shape, and a drum 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 body at the axis of the drum body. And. The drum body is rotatably provided with respect to the drum shaft, and the drum shaft is supported on the side walls in the width direction of the process unit 13 so as not to rotate. The photosensitive drum 71 is rotationally driven in the same direction (clockwise in the figure) as the moving direction of the conveying belt 81 at a position of contact with the conveying belt 81 described later during image formation.

The scorotron charger 72 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 72 does not contact the photosensitive drum 71 behind the photosensitive drum 71. Opposing to each other with an interval.
The developing cartridge 73 includes a developing roller 76, a supply roller 77, and a layer thickness regulating blade 78 in the casing.

  The developing roller 76 is disposed opposite to the photosensitive drum 71 in front of the photosensitive drum 71. The developing roller 76 has a metal roller shaft 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 76 is rotatably supported on both side walls in the width direction of the housing of the developing cartridge 73, and a developing bias is applied during image formation.

The supply roller 77 is disposed in front of the developing roller 76 so as to face the developing roller 76 and is in pressure contact with the developing roller 76. The supply roller 77 has a metal roller shaft covered with a roller portion made of a conductive sponge member. The roller shaft of the supply roller 77 is rotatably supported on both side walls in the width direction of the housing of the developing cartridge 73.
The layer thickness regulating blade 78 is made of a metal leaf spring material, and has a semicircular cross-sectional pressing member made of insulating silicone rubber at the tip. The layer thickness regulating blade 78 is supported by the housing of the developing cartridge 73 above the developing roller 76, and the pressing member at the tip (lower end) thereof is pressed against the developing roller 76 from above the front side. .

  The upper portion of the housing of the developing cartridge 73 is formed as a toner storage chamber 75 that stores toner, and each color toner is stored. That is, a positively chargeable nonmagnetic one-component polymerized toner having a yellow color is stored in the toner storage chamber 75 of the yellow process section 13Y. The toner storage chamber 75 of the magenta process unit 13M stores a positively chargeable nonmagnetic one-component polymerized toner having a magenta color. In the toner storage chamber 75 of the cyan process unit 13C, positively charged nonmagnetic one-component polymerized toner having a cyan color is stored. In the toner storage chamber 75 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 75 is supplied to the supply roller 77 and is supplied to the developing roller 76 by the rotation of the supply roller 77 during image formation. At this time, the toner is positively frictionally charged between the supply roller 77 and the developing roller 76 to which a developing bias is applied. The toner supplied onto the developing roller 76 enters between the layer thickness regulating blade 78 and the developing roller 76 as the developing roller 76 rotates, and becomes a thin layer having a constant thickness. It is carried on.

  On the other hand, the scorotron charger 72 generates a corona discharge by applying a charging bias to uniformly positively charge the surface of the photosensitive drum 71. The surface of the photosensitive drum 71 is uniformly positively charged by the scorotron charger 72 as the photosensitive drum 71 rotates, and then is emitted from each emission window 21 of the scanner unit 12 (first laser). The electrostatic latent image of each color corresponding to the image to be formed on the paper 3 is formed by the high-speed scanning of the light or the second laser light).

When the photosensitive drum 71 further rotates, the positively charged toner that is carried on the surface of the developing roller 76 then contacts the photosensitive drum 71 by the rotation of the developing roller 76, and the photosensitive drum 71. The electrostatic latent image formed on the surface, that is, the surface of the photosensitive drum 71 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 71 is visualized, and a toner image by reversal development is carried on the surface of the photosensitive drum 71 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 79, a driven roller 80, a conveyance belt 81, a transfer roller 82, and a belt cleaning unit 83.

The drive roller 79 is disposed rearward and lower than the photosensitive drum 71 of the black process unit 13K. The drive roller 79 is driven to rotate in the direction opposite to the rotation direction of the photosensitive drum 71 (counterclockwise in the figure) during image formation.
The driven roller 80 is disposed on the front lower side of the photosensitive drum 71 of the yellow process portion 13Y and is opposed to the driving roller 79 in the front-rear direction. The driven roller 80 is driven to rotate in the same direction as the driving roller 79 (counterclockwise in the figure) when the driving roller 79 is driven to rotate.

  The conveyor belt 81 is an endless belt, and is formed of a resin such as conductive polycarbonate or polyimide in which conductive particles such as carbon are dispersed. The conveyor belt 81 is wound between a driving roller 79 and a driven roller 80, and the wound outer contact surface is in contact with all of the photosensitive drums 71 of the respective process units 13. Is arranged.

Then, the driven roller 80 is driven by the driving roller 79, and the conveying belt 81 is photosensitive between the driving roller 79 and the driven roller 80 on the contact surface facing the photosensitive drum 71 of each process unit 13. In order to rotate in the same direction as the drum 71, it is rotated in the direction indicated by the arrow A (counterclockwise in the figure).
The transfer roller 82 is disposed so as to face the photosensitive drum 71 of each process unit 13 and the conveyor belt 81 in the conveyor belt 81 wound between the driving roller 79 and the driven roller 80. Each transfer roller 82 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 82 extends along the width direction and is rotatably supported, and a transfer bias is applied during transfer. Each transfer roller 82 rotates in the same direction (counterclockwise in the figure) as the circumferential movement direction of the conveyor belt 81 on the contact surface facing the conveyor belt 81.

  Then, the sheet 3 fed from the sheet feeding unit 4 is conveyed from the front to the rear by the conveyance belt 81 that is circulated by the drive of the driving roller 79 and the driven of the driven roller 80. It is conveyed so as to sequentially pass through image forming positions between the 13 photosensitive drums 71. During the conveyance, toner images corresponding to the respective colors carried on the photosensitive drums 71 of the respective process units 13 are sequentially transferred, whereby a color image is formed on the paper 3.

  That is, for example, when the yellow toner image carried on the surface of the photosensitive drum 71 of the yellow process unit 13Y is transferred to the sheet 3, the magenta toner carried on the surface of the photosensitive drum 71 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 71 of the cyan process unit 13C and the black process unit 13K by the same operation. The black toner image carried on the surface of the photosensitive drum 71 is transferred in a superimposed 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 83 is disposed below the transport belt 81 and opposed to the black process unit 13K with the transport belt 81 interposed therebetween.
The belt cleaning unit 83 is disposed so as to be in contact with the surface of the conveyance belt 81, a primary cleaning roller 84 for scraping off paper dust and toner attached to the surface of the conveyance belt 81, and the primary cleaning thereof. The secondary cleaning roller 85 is disposed in contact with the roller 84 and electrically collects paper dust and toner scraped off by the primary cleaning roller 84. The secondary cleaning roller 85 is in contact with the secondary cleaning roller 85 to perform secondary cleaning. A scraping blade 86 for scraping off the paper dust and toner collected by the roller 85 and a cleaning box 87 for storing the paper dust and toner scraped by the scraping blade 86 are provided.

In the belt cleaning unit 83, paper dust or toner attached to the surface of the conveyor belt 81 is first scraped off by the primary cleaning roller 84 and then scraped off by the primary cleaning roller 84. And the like are electrically collected by the secondary cleaning roller 85. Thereafter, paper dust and toner collected by the secondary cleaning roller 85 are scraped off by the scraping blade 86 and then stored in the cleaning box 87.
(Configuration of fixing unit)
The fixing unit 15 is disposed behind the transfer unit 14. The fixing unit 15 includes a heating roller 88, a pressure roller 89, and a conveyance roller 90. The heating roller 88 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 88 is heated to the fixing temperature by the halogen lamp. The pressure roller 89 is provided so as to press the heating roller 88. Further, the transport roller 90 includes a pair of upper and lower rollers, and is disposed behind the heating roller 88 and the pressure roller 89.

The color image transferred onto the sheet 3 is then conveyed to the fixing unit 15 and heated and pressed while the sheet 3 passes between the heating roller 88 and the pressure roller 89. 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 90.
(Configuration of paper output unit)
The paper discharge unit 6 includes a paper discharge path 91, a paper discharge roller 92, and a paper discharge tray 93.

  The discharge path 91 has an upstream end adjacent to the conveyance roller 90 in the lower part and the sheet 3 is conveyed rearward, and a downstream end is adjacent to the discharge roller 92 in the upper part. However, it is formed as a transport path for the substantially U-shaped sheet 3 so that the sheet 3 is discharged forward. The paper discharge roller 92 is provided as a pair of rollers at the downstream end of the paper discharge path 91. The sheet discharge tray 93 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 90 is discharged forward by the paper discharge roller 92 after the transport direction is reversed in the paper discharge path 91. The discharged paper 3 is placed on a paper discharge tray 93.
(Description of the scanner unit)
In such a color laser printer 1, in the scanner unit 12, in each position adjustment frame 24, the first laser emission unit 25 a is held on the first holder plate 30, and the second laser emission unit 25 b is attached to the second holder plate 31. By holding the first collimating lens 26a and the second collimating lens 26b on the base plate 32, the first laser emitting unit 25a, the first collimating lens 26a, the second laser emitting unit 25b, and the second collimating lens 26b are supported. The two collimating lenses 26b can be efficiently arranged to simplify the configuration and reduce the cost.

  In addition, after the first screw 52 is inserted into the first insertion hole 47 of the first long plate 45, the first screw 52 is adjusted in position and fixed to the first screwing hole 42 of the first screw fixing plate 37. By adjusting the relative arrangement of the long plate 45 and the first screw fixing plate 37, the position of the first laser emitting unit 25a can be adjusted with respect to the first collimating lens 26a. In addition, after the second screw 57 is inserted into the second insertion hole 51 of the second long plate 49, the second screw 57 is positioned and fixed to the second screwing hole 43 of the second screw fixing plate 38, thereby fixing the second screw 57. By adjusting the relative arrangement of the long plate 49 and the second screw fixing plate 38, the position of the second laser light emitting unit 25b can be adjusted with respect to the second collimating lens 26b. Therefore, position adjustment between the first laser light emitting unit 25a and the first collimating lens 26a and between the second laser light emitting unit 25b and the second collimating lens 26b can be easily achieved.

Each position adjustment frame 24 includes a first holder plate 30, a second holder plate 31, and a base plate 32 continuously and integrally, and is formed by bending one sheet metal. ing. Thereby, the number of parts can be reduced, the configuration can be simplified, and the cost can be reduced.
Further, in each position adjustment frame 24, the first screw 52 inserted through the first insertion hole 47 of the first long plate 45 can be advanced and retracted relative to the first screwing hole 42 of the first screw fixing plate 37. For example, the first collimator is adjusted by adjusting the relative positions of the first long plate 45 and the first lens groove 40 that are spaced apart in the opposing direction of the first long plate 45 and the first screw fixing plate 37. Accurate position adjustment of the first laser emission unit 25a with respect to the lens 26a can be achieved. Further, if the second screw 57 inserted through the second insertion hole 51 of the second long plate 49 is advanced and retracted with respect to the second screw hole 43 of the second screw fixing plate 38, the second long plate 49 and The second laser light emitting unit with respect to the second collimating lens 26b is adjusted by adjusting the relative positions of the second long plate 49 and the second lens groove 35 that are spaced apart in the direction facing the second screw fixing plate 38. An accurate position adjustment of 25b can be achieved.

  Moreover, in each laser irradiation optical part 18, since the relative position in the main scanning direction X of a 1st laser beam and a 2nd laser beam is made to correspond by the reflective mirror 28, the 1st laser light emission part 25a and the 1st collimating lens 26a And the second laser light emitting unit 25b and the second collimating lens 26b can be arranged at different positions in the sub-scanning direction Y to ensure an efficient layout thereof, and to reduce the size of the apparatus. Can do.

  Moreover, in each laser irradiation optical part 18, the 1st laser beam which passed the 1st collimating lens 26a and the 2nd laser beam which passed the 2nd collimating lens 26b are the 1st slit hole 55 and the 2nd slit hole 56, respectively. Then, the light enters the reflection mirror 28. The first laser beam after passing through the first slit hole 55 and the second laser beam after passing through the second slit hole 56 are limited in cross-sectional shape by the first slit hole 55 and the second slit hole 56, respectively. Thus, mutual interference between the first laser beam and the second laser beam is prevented. As a result, the relative position of the first laser beam and the second laser beam in the main scanning direction X can be made to coincide with each other accurately by the reflection mirror 28.

Further, in each laser irradiation optical unit 18, each reflecting mirror 28 is positioned and the mirror positioning member 58 to be held is formed integrally with the slit plate 27, so that the number of parts is reduced and the configuration is simplified. Can be achieved.
In each position adjustment frame 24, the sub-scanning direction Y is provided between the support plate 34 in which the first lens groove 40 is formed and the fixed plate 33 in which the second lens groove 35 is formed. Since the step portion 41 is provided, the first lens groove 40 and the second lens groove 35 can be easily arranged at different positions in the sub-scanning direction Y.

  Further, in each position adjustment frame 24, the first long plate 45 of the first holder plate 30 and the second long plate 49 of the second holder plate 31 are arranged in a substantially perpendicular direction, so the first long plate The first laser light emitting unit 25a held by 45 and the second laser light emitting unit 25b held by the second long plate 49 are arranged in a direction substantially perpendicular to each other. The relative position of the second laser light in the main scanning direction X can be matched with high accuracy. Further, an efficient layout of the first laser light emitting unit 25a and the second laser light emitting unit 25b can be ensured, and the apparatus can be miniaturized.

Further, in each position adjustment frame 24, the first screw fixing plate 37 and the second screw fixing plate 38 are bent from the fixing plate 33 in directions opposite to each other in the vertical direction. The screw fixing plate 37 and the second screw fixing plate 38 can be arranged at different positions in the sub-scanning direction Y, respectively.
In the scanner unit 12, two laser irradiation optical units 18 are arranged adjacent to each other on one side in the width direction with respect to the polygon mirror 17, and one set (the first laser beam and the first laser beam) is arranged. The second laser beam) and the other set of laser beams are incident on different deflection surfaces in parallel with the polygon mirror 17. In other words, in the scanner unit 12, the two laser irradiation optical units 18 are arranged so that a pair of laser beams emitted from the respective laser irradiation optical units 18 are irradiated to different deflection surfaces of the polygon mirror 17. Therefore, an efficient layout can be ensured and the apparatus can be downsized.

  Further, the scanner unit 12 includes two laser irradiation optical units 18, two first laser beams and two second laser beams emitted from the two first laser emission units 25 a and the second laser emission unit 25 b. That is, the four laser beams can be scanned by the polygon mirror 17 respectively. Therefore, an electrostatic latent image corresponding to each of yellow, magenta, cyan and black can be formed to form a color image.

Further, each laser irradiation optical unit 18 is configured so that one set of laser beams and the other set of laser beams are incident on the polygon mirror 17 in parallel. Is arranged. Therefore, each laser irradiation optical part 18 can be arranged compactly with respect to the polygon mirror 17.
In the color laser printer 1, electrostatic latent images are formed on the respective photosensitive drums 51 by the four laser beams emitted from the scanner unit 12. Therefore, an accurate electrostatic latent image can be formed on each photosensitive drum 51 to achieve accurate color image formation.

1 is a side sectional view showing an embodiment of a color laser printer as an image forming apparatus of the present invention. It is a top view of the scanner unit of the color laser printer shown in FIG. It is a perspective view which shows the optical system of the laser irradiation optical part of the scanner unit shown in FIG. It is a perspective view which shows the position adjustment frame of the laser irradiation optical part shown in FIG. It is a top view which shows the position adjustment flame | frame of the laser irradiation optical part shown in FIG. FIG. 3 is a side view showing an optical system of a laser emission optical unit in the scanner unit shown in FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Color laser printer 15 Photosensitive drum 16 Scanner unit 17 Polygon mirror 20 Laser emission optical part 25a 1st laser light emission part 25b 2nd laser light emission part 26a 1st collimating lens 26b 2nd collimating lens 27 Slit board 28 Reflecting mirror 30 1st holder Plate 31 Second holder plate 32 Base plate 33 Fixing plate 35 Second lens groove 37 First screw fixing plate 38 Second screw fixing plate 40 First lens groove 41 Stepped portion 45 First long plate 49 Second long plate 51 First Screw 55 First slit hole 56 Second slit hole 57 Second screw 58 Mirror positioning member

Claims (12)

A first holding member comprising a first holding part for holding a first laser light emitting part for emitting a first laser light, and a first screw insertion part for inserting a first screw;
A second holding member comprising a second holding part for holding a second laser light emitting part for emitting the second laser light, and a second screw insertion part for inserting the second screw;
The first lens support portion that supports the first lens through which the first laser light passes, the second lens support portion that supports the second lens through which the second laser light passes, and the first screw insertion portion. A first screw insertion fixing portion that is inserted to fix the first screw, and a second screw insertion fixing portion that is inserted to fix the second screw that is inserted into the second screw insertion portion. A base member, and a light deflecting unit that deflects and scans the first laser light and the second laser light in a main scanning direction ,
The first holding member, the second holding member, and the base member are formed continuously by bending a sheet metal,
The first screw insertion portion and the first screw insertion fixing portion are spaced apart from each other, and the first holding member and the first lens support portion are the first screw insertion portion and the first screw insertion portion. In the direction facing the one screw insertion fixing portion, it is arranged at an interval,
The distance between the first holding member and the first lens support portion is adjusted by advancing and retracting the first screw with respect to the first screw insertion fixing portion,
The second screw insertion portion and the second screw insertion fixing portion are spaced apart from each other, and the second holding member and the second lens support portion are the second screw insertion portion and the second screw insertion portion. In the opposite direction to the two screw insertion fixing portion, it is arranged at an interval,
Wherein the forward and backward with respect to the second screw insertion fixing portion of the second screw, a distance between the second holding member and the second lens support portion is characterized Rukoto adjusted, the optical scanning device. The first lens support part and the second lens support part are arranged at different positions in the sub-scanning direction,
The first laser light and the second laser light are reflected by reflecting at least one of the first laser light that has passed through the first lens support portion and the second laser light that has passed through the second lens support portion. 2. The optical scanning device according to claim 1, further comprising a light reflecting means for matching the relative positions in the main scanning direction. Between the first lens support and the light reflecting means in the optical path of the first laser light, and between the second lens support and the light reflecting means in the optical path of the second laser light, respectively. The optical scanning device according to claim 2 , further comprising a slit member in which the slit is opened. Positioning means for positioning the light reflecting means;
The optical scanning device according to claim 3 , wherein the slit member is formed integrally with the positioning unit. Said base member between the second lens support portion and the first lens support portion, wherein the stepped portion in the sub-scanning direction is provided, to one of the claims 1 to 4 The optical scanning device described. Said first retention member, wherein the second holding member, characterized in that it is disposed substantially perpendicular to each other, the optical scanning apparatus according to any one of claims 1 to 5. The base member includes a support member on which the first screw insertion fixing portion and the second screw insertion fixing portion are supported,
The first screw insertion fixing portion and the second screw insertion fixing portion are formed by being bent in opposite directions from the support member, according to any one of claims 1 to 6. The optical scanning device described. The first holding member, the second holding member and the base member are used as a set of optical elements, and a plurality of the optical elements are provided.
The light deflection means comprises a plurality of deflection surfaces,
The first laser beam and the second laser beam emitted from each of the optical elements are irradiated to different deflection surfaces of the optical deflection unit for each of the different optical elements. 8. The optical scanning device according to any one of 7 above. The optical scanning device according to claim 8 , comprising two optical elements. The first laser light and the second laser light emitted from one of the optical elements, and the first laser light and the second laser light emitted from the other optical element serve as the light deflecting unit. On the other hand, each said optical element is arrange | positioned so that it may inject in parallel, The optical scanning device of Claim 9 characterized by the above-mentioned. An optical scanning device according to any one of claims 1 to 10 ,
Provided for each laser beam of the first laser beam and the second laser beam scanned in the main scanning direction by the light deflecting means, and each laser beam is irradiated, and an electrostatic latent image is formed by the irradiation. An image forming apparatus comprising a plurality of photosensitive members. An optical scanning device according to claim 9 or 10 ,
Provided for each of the two laser beams of the first laser beam and the second laser beam scanned in the main scanning direction by the light deflecting means, and each laser beam is irradiated, and the electrostatic latent image is irradiated by the irradiation. Comprising four photoreceptors each of which is formed,
An image forming apparatus, wherein the electrostatic latent images formed on the respective photoconductors are developed with different colors.

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