JP4217019B2 - Multi-beam recording head and image forming apparatus having the multi-beam recording head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multibeam recording head and an imaging apparatus in which an image pattern of identical quality can be formed, even if a plurality of single dots or single lines are formed in the subscanning direction with a plurality of beams in order to deal with high speed imaging or high resolution. <P>SOLUTION: The multibeam recording head comprises an exposure light source 2 including a laser device for irradiating a rotary polygon mirror 1 with a beam (B), a main beam head 3 where two or more integer beams (B<SB>1-</SB>N) of exposure light sources 2<SB>1-</SB>N perform exposure while being arranged at a constant exposure light source interval (L) in the subscanning direction, and an auxiliary beam head 5 where auxiliary exposure light source 4<SB>1-n</SB>equal to the exposure light sources 2<SB>1-</SB>N perform exposure with beams (b<SB>1-n</SB>) of one or more integer auxiliary exposure light source 4<SB>1-n</SB>smaller than the number of the exposure light sources 2<SB>1-</SB>N. The beam (b<SB>1</SB>) of the first auxiliary exposure light source 4<SB>1</SB>in the auxiliary beam head 5 is located at a position separated by the exposure light source interval (L), in the subscanning direction from the beam (BN) of the last exposure light source 2N of the main beam head 3. <P>COPYRIGHT: (C)2003,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multi-beam recording head and an image forming apparatus including the multi-beam recording head. More specifically, the present invention relates to a multi-beam recording head in which a plurality of beams simultaneously perform scanning exposure, and a toner image formed by an electrophotographic method. The present invention relates to an image forming apparatus equipped with a multi-beam recording head such as a copying machine, a printer, a facsimile machine, or a complex machine formed with a multi-beam recording head.
[0002]
[Prior art]
In conventional image forming apparatuses, a laser for exposing the surface of an image carrier in order to cope with higher speed and higher resolution of image formation in the field of image forming apparatuses such as digital electrophotographic copying machines and laser printers. Various types of multi-beam recording heads configured to emit a plurality of beams and an image forming apparatus including the multi-beam recording head have been proposed.
In an image forming apparatus such as a digital electrophotographic copying machine or a laser printer, a photosensitive member of an image carrier needs to be rotated at a high linear speed for high resolution and high speed printing output.
In response to this, the laser device (LD) beam scanning exposure system of the multi-beam recording head also needs to increase the rotation of the polygon mirror of the rotating polyhedral body and increase the image scanning frequency in the sub-scanning direction.
However, the rotational speed of the polygon mirror of the rotating polyhedral body is currently around 30,000 (rpm), and in order to obtain a higher rotational speed, the bearing of the polygon mirror of the rotating polyhedral body is improved. There are difficult issues.
Therefore, in order to achieve high resolution without increasing the number of rotations of the polygon mirror of the rotating polyhedral body, a plurality of beam light sources are arranged in the sub-scanning direction, and a plurality of beams are scanned by one scan in the main scanning direction. A multi-beam scanning exposure method using a multi-beam recording head has come to be adopted.
In this method using a multi-beam recording head, the number of rotations of the polygon mirror of the rotating multi-specular body required in the case of only one beam light source can be reduced to half the number of rotations by using a two-beam light source. Exposure scanning, which was impossible in the case of a beam, becomes possible, and even if exposure scanning with one beam is possible, there will be a margin in rotation. There are great advantages such as increasing the linear velocity, that is, increasing the number of rotations of the polygon mirror of the rotating multi-specular body and enabling high-speed output.
In a laser printer device for a thermal printer using a thermal transfer ribbon, a correction laser beam narrower than a laser beam for one dot is disposed outside both ends of a plurality of laser beams, and the intensity of the correction laser beam is adjusted. It is changed with the data of the dot of the current line and / or the next line, and the gap between the lines is corrected, or the ends of the plurality of laser beams overlap at least one dot with the previous line, and the overlapped dots are performed twice. When printing a plurality of dots as a line by correcting so as to be in a predetermined state by printing, it is also known to prevent streaks between lines (see Japanese Patent Laid-Open No. Hei 6-198952). reference).
[0003]
A light source device in which each beam emitted from a plurality of laser light sources irradiates a recording medium at predetermined intervals via a deflecting device is used, for example, around the optical axis of the beam 1 with the beam 1 as a reference. By rotating a predetermined angle in the range of angle θ1 to angle θ2 and scanning with beam 1 and beam 2, pitches P1 to P2 in the sub-scanning direction are obtained, and when the rotation angle is small, θ1 is high. It is also known that a fine pitch P1 can be obtained, and a coarse pitch P3 can be obtained when θ2 has a large rotation angle, so that the scanning pitch of the multi-beam can be changed as required (Japanese Patent Laid-Open No. Hei 9). (See publications such as -193458).
N lasers each having a semiconductor laser array in which three or more n light emitting points are arrayed at equal intervals in the same package as a light source, and emitted from the n light emitting points on the recording medium. In a multi-beam scanning device that records information by scanning with a beam, the adjacent light emitting point intervals of the n light emitting points are set to be equal to or less than the information recording density interval of information recorded on the recording medium, respectively. The n light emitting points are arranged in such a manner that the n laser beams are arranged on the recording medium in a line or substantially in a direction perpendicular to the main scanning direction of the laser beam at the information recording density interval. An image forming apparatus which is a digital electronic copying machine on which a beam scanning device is mounted is also known (see Japanese Patent Laid-Open No. 2001-281578).
However, when a plurality of laser device (LD) light sources are arranged and the number thereof is N, in the multi-beam scanning exposure of the multi-beam recording head, one main scanning direction is performed on one surface of the rotating polygon mirror of the rotating polyhedral body. When the above exposure is performed, N multi-beam lines are simultaneously exposed on the photoreceptor of the image carrier.
[0004]
One beam usually has an elliptical beam shape, and the beams partially overlap each other. Therefore, when viewed at one point on the photoreceptor, an extremely strong power is irradiated at a time.
Then, when N multi-beam lines are scanned and exposed on the next surface of the polygon mirror of the rotating polyhedral body, the beams of the previous last line (Nth) and the current first line (first) are scanned. Are overlapped with each other to be scanned and exposed.
In this case, when viewed at one point on the photosensitive member of the image carrier, the strong power is exposed twice.
That is, even if the exposure energy given to the photosensitive member of the image carrier is the same, in the multi-beam optical system of the multi-beam recording head, essentially one point on the photosensitive member receives the same exposure energy once, and 2 Depending on the photosensitive member of the image carrier, there may be a so-called reciprocity failure, which results in different effects even when the same exposure energy is received. The inventors of the invention according to the present patent application have pointed out.
Specifically, when forming an image of one dot or one line with a plurality of beams, if the image bearing member has a strong reciprocity failure, the plurality of beams are subjected to simultaneous scanning exposure or one beam. Depending on the sequential exposure, there is a problem that the density and thickness of one dot or one line that is formed changes.
Temporarily, in the image writing apparatus of 4LD multi-beam head scanning exposure, when 1 dot or 1 line is formed with 2 beams, the cause of the difference in density or thickness of the dot or line depending on the location is analyzed. One image is the case where two beams of the multi-beam recording head are exposed simultaneously, and the other is the last fourth beam of the multi-beam recording head and the first beam in the next scan. It was found that this was the case where two beam exposures with a time difference were made.
[0005]
Depending on the photosensitive member of the image carrier, the effect may differ depending on how the same exposure energy is applied, which is said to be a reciprocity failure of the photosensitive member of the image carrier.
Usually, exposure energy = light power (value per unit time, unit area) × exposure time. However, if (1) light power 1 and exposure time 1 are assumed, and (2) light power 2 and exposure. When the time is 0.55, or (3) when the light power is 0.5 and the exposure time is 2, or (4) the exposure energy is repeated twice with a time difference of light power 0.5 × exposure time 1. In both cases, the exposure energy is 1, but there are photoconductors with different effects and photoconductors with almost the same effect.
It has been found that the multi-beam scanning exposure of the multi-beam recording head includes the essential problem that the writing condition changes as described above even when the same image information is written.
Therefore, the conventional multi-beam recording head and the image forming apparatus equipped with the multi-beam recording head are sub-scanned with one beam or one line with a plurality of beams in order to cope with higher speed of image formation and higher resolution. When a plurality of images are formed in the direction, there has been a problem that an image pattern of the same quality cannot be formed depending on the location.
[0006]
[Problems to be solved by the invention]
A conventional multi-beam recording head and an image forming apparatus equipped with the multi-beam recording head are arranged so that one dot or one line in a sub-scanning direction is used with a plurality of beams in order to cope with high-speed image formation and high resolution. When a plurality of images are formed, there has been a problem that image patterns of the same quality cannot be formed.
Therefore, an object of the present invention is to solve such problems. That is, a multi-beam recording head capable of forming an image pattern of the same quality even if a plurality of dots or one line are formed in the sub-scanning direction with a plurality of beams in order to cope with an increase in image formation speed and resolution. An object of the present invention is to provide an image forming apparatus including a multi-beam recording head that forms a high-quality image at high speed.
[0007]
[Means for Solving the Problems]
  In order to achieve the above object, the present invention of claim 1 is a multi-beam recording head that performs scanning exposure with a plurality of beams at the same time. A beam head that irradiates the rotating multi-specular body with a beam, and the beam head includes a plurality of the exposure light sources arranged at equal intervals in the sub-scanning direction. A main beam head that forms a pattern by simultaneously turning on the exposure light source, and an auxiliary beam head that has one or more exposure light sources and is less than the number of the exposure light sources that the main beam head has, and The auxiliary beam head is separate from the main beam head, and is disposed downstream of the main beam head in the sub-scanning direction and downstream of the main beam head in the main scanning direction. The exposure light source upstream of the auxiliary beam head in the sub-scanning direction is arranged downstream of the exposure light source downstream of the main beam head in the sub-scanning direction. After the beams irradiated from the plurality of exposure light sources of the main beam head are simultaneously scanned and exposed by one surface of the rotating multi-specular body, the rotating multi-specular body is disposed at positions separated from each other. When the next scanning exposure is simultaneously performed by the next adjacent surface, the beam from the last line of the main beam head at the time of scanning exposure by the one surface and the main scanning at the time of scanning exposure by the next surface When the beam from the first line of the beam head partially overlaps in the sub-scanning direction and two scanning exposures are performed with a time difference corresponding to the sub-scanning period, The exposure light source of the main beam head and the auxiliary beam head during the scanning exposure are turned on, and the exposure light source of the first line of the main beam head is turned off during the scanning exposure by the next surface. Simultaneous scanning with a plurality of exposure light sources of the main beam head by performing simultaneous scanning exposure with the beam from the exposure light source of the auxiliary beam head that is turned on and the beam from the last line of the main beam head The most important feature is that the pattern is formed under the same writing conditions as in the case of exposure.
  According to a second aspect of the present invention, in the multi-beam recording head according to the first aspect, the wavelength, size, and power of the beam of the exposure light source included in the auxiliary beam head are the same as those of the exposure light source included in the main beam head. It is the same as the wavelength, size and power of the beam.
  The present invention of claim 3 is formed by an electrophotographic method.Latent image3. An image forming apparatus for forming an image on a multi-beam recording head, wherein the image carrier is rotatably held, and a latent image is formed by scanning and exposing the surface of the image carrier. Formed by a beam recording head and the multi-beam recording headLatent imageAnd developing means for developing the toner image, and transfer means for transferring the toner image visualized by the developing means to the transfer medium.
[0008]
[Action]
  The multi-beam recording head configured as described above and the image forming apparatus including the multi-beam recording head are rotatably held in the multi-beam recording head that performs scanning exposure simultaneously with a plurality of beams. A rotating multi-specular body having a multi-mirror surface, and a beam head having a plurality of exposure light sources and irradiating the rotating multi-specular body with a beam. A main beam head that is arranged at equal intervals in the scanning direction and forms a pattern by simultaneously lighting a plurality of the exposure light sources, and less than the number of the exposure light sources that the main beam head has, and one or more An auxiliary beam head having an exposure light source, the auxiliary beam head being separate from the main beam head and in the sub-scanning direction. An exposure light source disposed downstream of the main beam head and downstream of the main beam head in the main scanning direction, the most upstream exposure light source in the sub scanning direction of the auxiliary beam head is the most downstream exposure light source in the sub scanning direction of the main beam head. On the other hand, the beam irradiated from the plurality of exposure light sources of the main beam head is arranged at a position separated from the arrangement distance of the exposure light source of the main beam head downstream in the sub-scanning direction. When the next scanning exposure is simultaneously performed by the next adjacent surface of the rotating polyhedral body after the simultaneous scanning exposure by one surface of the main surface of the main beam head, The beam from the last line and the beam from the first line of the main beam head at the time of scanning exposure by the next surface partially overlap in the sub-scanning direction, When scanning exposure is performed twice with a time difference corresponding to the scanning cycle, the last line of the main beam head and the exposure light source of the auxiliary beam head at the time of scanning exposure by the one surface are turned on, During scanning exposure by a surface, the exposure light source of the first beam of the main beam head is turned off, and the beam from the exposure light source of the auxiliary beam head that is turned on and the beam from the last line of the main beam head By performing simultaneous scanning exposure, the pattern is formed under the same writing conditions as in the case of simultaneous scanning exposure using a plurality of exposure light sources of the main beam head.
  According to a second aspect of the present invention, an integral number of two or more beams of an exposure light source composed of a laser device that irradiates a beam onto a rotating multi-specular surface that is rotatably held and performs scanning is set in the sub-scanning direction or the like. The first of the auxiliary beam heads that perform exposure with a beam of an integral number of auxiliary exposure light sources when the number of auxiliary exposure light sources equal to or larger than the number of exposure light sources is equal to or less than the number of exposure light sources. The beam of the auxiliary exposure light source is arranged at a position separated from the beam of the last exposure light source of the main beam head in the sub-scanning direction by the exposure light source interval, and the auxiliary beam head has the same wavelength, size and power as the beam of the main beam head. Thus, a plurality of beams simultaneously perform scanning exposure.
  According to a third aspect of the present invention, a latent image is formed by performing scanning exposure on the surface of the image carrier that is rotatably held, and formed by the multi-beam recording head according to the first or second aspect.Latent imageThe toner image visualized by the developing means for developing the toner is transferred to the transfer medium by the transfer means, and the toner image is formed by an electrophotographic method.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the drawings.
1 and 2, a multi-beam recording head 0 in which a plurality of beams simultaneously perform scanning exposure is a polygon mirror of a rotating polyhedral body 1 composed of a multi-mirror surface that is held rotatably and performs scanning. Beam (B_{1 to N}Exposure light source 2 comprising a laser device_{1 to N}And the exposure light source 2_{1 to N}An integer number of beams (B_{1 to N}) In the sub-scanning direction of the arrow (Y) shown in the figure, and the exposure light source 2 of the main beam head 3 and the exposure light source 2 of the main beam head 3 for performing exposure with the exposure light source interval (L) being equally spaced._{1 to N}And the auxiliary exposure light source 4 equivalent to the above_{1 to n}Is the exposure light source 2_{1 to N}The number of auxiliary exposure light sources 4 is an integer of 1 or more which is less than the number of_{1 to n}Beam (b_{1 to n}), And the first auxiliary exposure light source 4 of the auxiliary beam head 5.₁Is the last exposure light source 2 of the main beam head 3_NBeam (B_N) From the exposure light source interval (L) in the sub-scanning direction of the arrow (Y) shown in the figure, and one dot or one line with a plurality of beams to cope with higher speed of image formation, higher resolution, etc. The image pattern of the same quality can be formed even if a plurality of are formed in the arrow (Y) sub-scan direction shown in the figure.
By making the wavelength, size and power of the beam (b) of the auxiliary beam head 5 in particular the same as the wavelength, size and power of the beam (B) of the main beam head 3, an image pattern of the same quality can be obtained. The multi-beam recording head 0 to be formed can be provided. .
[0011]
Exposure light source 2_{1 to N}The main beam head 3 and the auxiliary exposure light source 4 comprising_{1 to n}A plurality of beams (B_{1 to N}) And beam (b_{1 to n}) Is made to be a parallel light beam or a substantially parallel light beam by the colletment lens 6, and the light beam is regulated by the aperture 7.
A plurality of beams (B_{1 to N}) And beam (b_{1 to n}) Enters the polygon mirror of the rotating mirror body 1 through the mirror 9 from the cylinder lens 8.
Then, by rotating the rotating polyhedral body 1, a plurality of beams (B_{1 to N}) And beam (b_{1 to n}) Repeatedly scans a plurality of times in the main scanning direction of the arrow (X) shown in the figure.
A plurality of beams (B) are reflected by the polygon mirror of the rotating polyhedral body 1._{1 to N}) And beam (b_{1 to n}) Becomes convergent light by the fθ lens 10 and the toroidal lens 11 which are the image forming system, and is arranged at the image forming position which is the beam waist position via the mirror 12 and the dust-proof glass 13. The image is projected as a light spot on the photoconductive drum of the carrier 101 or the scanned surface of an endless photoconductive belt (not shown).
The mirror 14 is arranged outside the area of the effective scanning width, and the detector 15 is also arranged outside the area of the effective scanning width. The mirror 14 and the detector 15 perform the arrow shown in the drawing for each scan. A plurality of beams (B) moving in the main scanning direction of (X)_{1 to N}) And beam (b_{1 to n}) Is detected and the writing position is synchronized.
[0012]
In FIG. 3, the multi-beam recording head 0 includes the exposure light source 2._{1 to N}An integer number of beams (B_{1 to N}) For performing exposure with exposure light source intervals (L) of equal intervals in the sub-scanning direction, and the exposure light source 2 of the main beam head 3_{1 to N}The auxiliary exposure light source 4 equivalent to the above and the auxiliary exposure light source 4_{1 to n}Is the exposure light source 2_{1 to N}The number of auxiliary exposure light sources 4 is an integer of 1 or more which is less than the number of_{1 to n}Beam (b_{1 to n}The auxiliary beam head 5 that performs the exposure in step (1). Although not shown, the auxiliary beam head 5 may be disposed at a position of the main beam head 3 on the side of the sub-scanning direction of the arrow (Y) shown in the figure. By arranging it at the position on the scanning direction side, it becomes easy to adjust the writing pitch to cope with higher speed of image formation and higher resolution, and multi-beam recording that can form image patterns of the same quality. It became possible to provide a head.
[0013]
In FIG. 4, the multi-beam recording head 0 is the exposure light source 2 in the main beam head 3 as a specific example of a pattern in which a plurality of beams form one line._{1 to N}An integer number of beams (B_{1 to N}N = 4, and the auxiliary exposure light source 4 in the auxiliary beam head 5_{1 to n}Beam (b_{1 to n}) Where n = 1.
Individual laser, exposure light source 2_{1 to N}An integer number of beams (B_{1 to N}) And the auxiliary exposure light source 4_{1 to n}Is the exposure light source 2_{1 to N}The number of auxiliary exposure light sources 4 is an integer of 1 or more which is less than the number of_{1 to n}Beam (b_{1 to n}), The writing pitch of the image carrier 101 on the photosensitive roller or photosensitive belt in the image forming apparatus 100 (not shown) is 1200 dpi in the sub-scanning direction indicated by the arrow (Y) shown in the drawing, approximately 21.2 μm. Pitch.
Further, during the writing in the main scanning direction in the direction of the arrow (X) shown in the figure, the exposure light source 2 described above._{1 to N}And the auxiliary exposure light source 4_{1 to n}Was continuously lit.
In this pattern, one line is formed by two beams, but an interval of five beam lines is provided between one line and the next one line.
The exposure light source 2 of the first scanning by the polygon mirror of the rotating mirror body 1₁Beam (B₁) And the above exposure light source 2₂Beam (B₂) Beam scanning is simultaneous exposure.
Then, the exposure light source 2 in the second scanning by the polygon mirror of the rotating polyhedral body 1 is used.₄Beam (B₄The exposure light source 2 in the beam scanning and the third scanning by₁Beam (B₁) Beam scanning is performed twice with a time difference.
The period of the writing condition in the image pattern formation is restored to the original, that is, the exposure light source 2 in the eighth scanning of the polygon mirror of the rotating mirror body 1.₁Beam (B₁) And the above exposure light source 2₂Beam (B₂) In the simultaneous exposure.
In this pattern, there are three lines by simultaneous exposure between the lines by two exposures with a time difference (the second is omitted in the figure).
When this pattern was formed without the auxiliary beam head 5 and an image was taken out, the line portion formed by the two-time exposure with a time difference was formed thicker than the line formed by the two-beam simultaneous exposure, and the line became non-uniform.
Here, using the auxiliary beam head 5, the auxiliary exposure light source 4 of the auxiliary beam head 5 is interlocked with the rotation of the rotating multi-specular body 1 during the second scanning of the rotating mirror body 1.₁And the exposure light source 2 of the main beam head 3 for the third scanning of the rotating mirror body 1 is turned on.₁And the auxiliary exposure light source 4 is turned off.₁And the above exposure light source 2₁A uniform line was formed by reliable switching.
In this way, all the lines are simultaneously exposed to two beams, a uniform line is formed, and it is possible to provide a multi-beam recording head that can form an image pattern of the same quality.
[0014]
In FIG. 5, in the printer of the image forming apparatus 100, the endless photoconductor belt of the image carrier 1 is driven to rotate clockwise in the direction of the arrow (A) shown in the figure. Four sets of black developing device 102a, cyan developing device 102b, magenta developing device 102c, yellow developing device 102d of the multi-beam head 0 and developing means 102, and a transfer rotating in the direction of the arrow (C) shown as an intermediate transfer member. The intermediate transfer belt 103a of the means 103, the photoconductor cleaning device 105, and the like are disposed.
When a printing operation of an image forming operation by the printer of the image forming apparatus 100 is executed, a high voltage is applied to the charger 104, whereby the photosensitive belt of the image carrier 101 is uniformly charged. The
In an image signal processing unit (not shown), color image information, for example, a color image signal sent from an external computer is converted into an optical writing signal and sent to the multi-beam head 0.
In the multi-beam head 0, the laser of the exposure light source 2 of the main beam head 3 (not shown) and the auxiliary exposure light source 4 of the auxiliary beam head 5 (not shown) is controlled based on the optical writing signal, and the rotating multi-specular surface Optical writing corresponding to black, cyan, magenta, and yellow image signals via the polygon mirror of the body 1, the f / θ lens 10, the mirror 12, and the like Then, an electrostatic latent image is formed on the photosensitive belt of the image carrier 101.
[0015]
The electrostatic latent image on the endless photoreceptor belt of the image carrier 101 is obtained by the black developing device 102a, the cyan developing device 102b, the magenta developing device 102c, and the yellow developing device 102 having the respective color toners. Each color is developed by the developing device 102d.
As a result, a toner image is formed for each color on the endless photoreceptor belt of the image carrier 101.
At the contact portion between the endless photosensitive belt of the image carrier 101 and the intermediate transfer belt 103a, the intermediate transfer belt 103a is charged with a charge having a polarity opposite to that of the toner by the primary bias roller 103b of the transfer means 103. By applying the toner image, the toner image on the photosensitive belt of the image carrier 101 is transferred onto the intermediate transfer belt 103a.
By repeating this toner image formation and transfer operation four times, a four-color color toner image is formed on the intermediate transfer belt 103a.
The color toner image on the intermediate transfer belt 103a is transferred onto the transfer sheet (P) transferred from the paper feed cassette 106 by the paper feed roller 107, the transport roller pair 108, and the transport roller pair 109. The image is transferred by a secondary bias roller 103 c as 103.
The transfer sheet (P) to which the color toner image is transferred is conveyed to the fixing device 110, where the toner image is melted and fixed, and is discharged to the discharge unit 111 and stored. Yes.
The intermediate transfer belt 103a is suspended from the primary bias roller 103b, the drive roller 103d, the cleaning counter roller 103e, the secondary transfer counter roller 103f, and the tension roller 103g of the transfer unit 103, and the arrow C shown in the figure. Rotate in the direction.
Therefore, even if a plurality of dots or one line are formed with multiple beams in the sub-scanning direction in order to cope with high-speed image formation, high resolution, etc., the same quality image pattern can be formed, and high-speed and high-quality images can be formed. The image forming apparatus 100 including the multi-beam recording head 0 capable of forming the image can be provided.
[0016]
【The invention's effect】
  Since the present invention is configured as described above, according to the first aspect of the present invention, one dot or one line is subdivided by a plurality of beams in order to cope with high speed image formation and high resolution. It has become possible to provide a multi-beam recording head that can form an image pattern of the same quality even if a plurality of images are formed in the scanning direction.
In addition, a uniform line is formed by surely switching between the auxiliary exposure light source and the exposure light source, and one dot or one line with a plurality of beams is applied in the sub-scanning direction in order to cope with high-speed image formation and high resolution. In addition, it is possible to provide a multi-beam recording head that can form a high-quality image at a high speed with the same quality image pattern even if a plurality of the same are formed.
  According to the second aspect of the present invention, even if one dot or a plurality of lines are formed in the sub-scanning direction with a plurality of beams in order to cope with an increase in the speed and resolution of image formation, an image of the same quality can be obtained. A multi-beam recording head capable of forming a pattern can be provided.
  Claim3According to the invention, a toner image formed by an electrophotographic method is formed by forming a single dot or a plurality of lines in the sub-scanning direction with a plurality of beams in order to cope with an increase in image formation speed and resolution. Even when formed, it is possible to provide an image forming apparatus including a multi-beam recording head capable of forming an image pattern of the same quality and forming a high quality image at high speed.
[Brief description of the drawings]
FIG. 1 is an enlarged perspective view for explaining the outline of a multi-beam recording head according to an embodiment of the present invention.
FIG. 2 is a perspective view illustrating a multi-beam recording head showing an embodiment of the present invention.
FIG. 3 is an explanatory diagram for explaining a main part of a multi-beam recording head showing an embodiment of the present invention.
FIG. 4 is an explanatory diagram illustrating a state of another main part of a multi-beam recording head showing an embodiment of the present invention.
FIG. 5 is an explanatory diagram illustrating an image forming apparatus including a multi-beam recording head according to an embodiment of the present invention.
[Explanation of symbols]
0 Multi-beam recording head
1 Rotating multi-specular body
2 Exposure light source, 2₁  First exposure light source,
2_n  Last exposure light source
3 Main beam head
4 Auxiliary exposure light source, 4₁  The first auxiliary exposure light source,
4_n  Last auxiliary exposure light source
5 Auxiliary beam head
6 Correment lenses
7 Aperture
8 Cylinder lens
9 Mirror
10 fθ lens
11 Toroidal lens
12 Mirror
13 Dust-proof glass
14 Mirror
15 Detector
100 Image forming apparatus
101 Image carrier
102 developing means, 102a black developing device,
102b cyan developing device,
102c magenta developing device,
102d Yellow developing device
103 transfer means, 103a intermediate transfer belt,
103b primary bias roller,
103c secondary bias roller,
103d driving roller,
103e cleaning counter roller,
103f secondary transfer counter roller,
103g tension roller
104 Charger
105 Photoconductor cleaning device
106 Paper cassette
107 Feed roller
108 Conveying roller pair
109 Conveyor roller pair
110 Fixing device
111 Paper exit

Claims (3)

In a multi-beam recording head that scans and exposes simultaneously with multiple beams,
A rotating multi-specular body having a multi-specular surface rotatably held;
A beam head having a plurality of exposure light sources and irradiating the rotating multi-specular body with a beam;
With
The beam head is
A plurality of exposure light sources arranged at equal intervals in the sub-scanning direction, and a main beam head that forms a pattern by simultaneously lighting the plurality of exposure light sources;
An auxiliary beam head having less than the number of exposure light sources of the main beam head and having one or more exposure light sources;
With
The auxiliary beam head is separate from the main beam head, and is disposed downstream of the main beam head in the sub-scanning direction and downstream of the main beam head in the main scanning direction,
The most upstream exposure light source in the sub-scanning direction of the auxiliary beam head is arranged with the exposure light source of the main beam head downstream in the sub-scanning direction with respect to the most downstream exposure light source in the sub-scanning direction of the main beam head. Placed at spaced apart positions,
After the beams irradiated from the plurality of exposure light sources of the main beam head are simultaneously scanned and exposed by one surface of the rotating polyhedral body, the next surface is adjacent to the next surface of the rotating polyhedral body. When scanning exposure is performed simultaneously, the beam from the last line of the main beam head at the time of scanning exposure by the one surface and the beam from the first line of the main beam head at the time of scanning exposure by the next surface Are partially overlapped in the sub-scanning direction, and two scanning exposures with a time difference corresponding to the sub-scanning period are performed,
An exposure light source of the main beam head at the time of scanning exposure by the one surface and an exposure light source of the auxiliary beam head are turned on, and an exposure light source of the first line of the main beam head at the time of scanning exposure by the next surface The plurality of exposure light sources of the main beam head by performing simultaneous scanning exposure with the beam from the exposure light source of the auxiliary beam head turned on and the beam from the last line of the main beam head The multi-beam recording head is characterized in that the pattern is formed under the same writing conditions as in the case of simultaneous scanning exposure by.   The wavelength, size, and power of the beam of the exposure light source included in the auxiliary beam head are the same as the wavelength, size, and power of the beam of the exposure light source included in the main beam head. The multi-beam recording head described in 1. In an image forming apparatus for forming a latent image formed by an electrophotographic method with a multi-beam recording head,
An image carrier held rotatably;
The multi-beam recording head according to claim 1 or 2, wherein the surface of the image carrier is scanned and exposed to form a latent image;
Developing means for developing and developing the latent image formed by the multi-beam recording head;
Transfer means for transferring the toner image visualized by the developing means to a transfer target;
An image forming apparatus comprising:

Images