JPH10181087A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct positional shift of scanning lines of two exposure optical systems by moving the whole of an optical scanning apparatus. SOLUTION: Exposure optical support members (H1, H2) supporting first exposure optical systems (Uk, Um) and second exposure optical systems (Uy, Uc) wherein laser beam incident directions to surfaces to be scanned (surfaces of image supports 16k, 16y; 16m, 16c) are set non-parallelly in a mutually fixed state are supported in a state capable of advancing and retreating in far and near directions with respect to the respective image supports, capable of being regulated around the axis parallel to a sub-scanning direction in rotary position and capable of being regulated around the axis parallel to the main scanning direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a laser printer, a laser copying machine, and a laser facsimile, and more particularly, to a plurality of image carriers by deflecting a plurality of light beams by a deflector having a rotating polygon mirror. Forming an electrostatic latent image thereon, developing each of the electrostatic latent images into a toner image of a different color,
The present invention relates to an image forming apparatus for transferring each of the toner images in a superimposed manner on a transfer target member. The present invention is used for reducing the displacement of the toner images when the toner images of different colors are superimposed and transferred onto the transfer target member.

[0002]

2. Description of the Related Art Conventionally, the following technologies (J01) and (J02) are known as image forming apparatuses of the type described above. (J01) Technology described in Japanese Patent Application Laid-Open No. 3-42612 This publication discloses a color printer using four sets of an optical scanning device in which a light source, a rotary polygon mirror, and an imaging lens are mounted in one housing (support member) and an image carrier. Techniques for obtaining images are described.
In this technique, the distance between a plurality of image carriers is shortened by arranging an optical scanning device such that a rotation axis of a rotary polygon mirror is horizontal, thereby reducing the size of the image forming apparatus. FIG. 6 of this publication shows an image forming apparatus in which an optical scanning device having a rotating polygon mirror for each image carrier is arranged in tandem. FIG. An optical scanning device of a spray paint system sharing one rotating polygon mirror is described. In such an image forming apparatus, in order to prevent a color shift from occurring when toner images of respective colors are superimposed, the position of an image written on a scanned surface of an image carrier by a laser beam is accurately aligned. There is a need to.

(Problem of (J01)) FIG. 11 is an explanatory diagram of a positional shift of a line image formed by scanning lines on a surface to be scanned by a plurality of laser beams. In FIG. 11, L1
Indicates a line image formed by the first laser beam and transferred to the transfer material, L2 indicates a line image formed by the second laser beam and transferred to the transfer material, and if there is no displacement, , L1 and L2 are line images that should overlap. In FIG. 11, a shift in the sub-scanning direction while L1 and L2 remain parallel is called a "lead registration difference".
The fact that the line images L1 and L2 are not parallel (that is, the scanning lines are not parallel) is called a "skew difference", and means that the lengths of the line images L1 and L2 in the main scanning direction, which should be the same length, are different. It is called "magnification difference". The shift between the line images L1 and L2 shown in FIG. 11 (that is, the shift of the scanning line on the surface to be scanned) is corrected by moving a folding mirror or the like in the optical scanning device in the conventional technique such as (J01). Was. However, there is a problem that the mirror may be deformed by the mirror moving mechanism.

(J02) Technology described in Japanese Patent Application Laid-Open No. 3-167666 discloses a technology for preventing deformation of the mirror by an additional member. However, (J02)
In the technique of the above, the configuration of the additional member is complicated.

As another method for correcting the positional deviation shown in FIG. 11, the following method can be considered. (J03) Method of Correcting Positional Displacement by Moving and Adjusting the Entire Optical Scanning Device However, the technique of (J03) is not applicable to a tandem system in which a plurality of independently configured exposure optical systems are juxtaposed. It is easy to adjust independently for each line, but in the spray paint system where multiple exposure optical systems share a rotating polygon mirror, moving the entire optical scanning device moves all scanning line positions. was there.

[0006]

Therefore, the following technology (J04) has conventionally been proposed. (J04) Technique described in Japanese Patent Application Laid-Open No. 3-142411 This publication describes a technique for rotating the entire optical system excluding the rotary polygon mirror around the optical center of the reflection surface of the rotary polygon mirror. . However, it is difficult to align the center of rotation with the optical center due to the mechanical configuration, and there is a concern that the distance between the rotating polygon mirror and the imaging lens fluctuates due to the adjustment, thereby deteriorating the optical performance.

In the above-mentioned spray paint method, in order to prevent deformation of mirrors and the like, to maintain the positional relationship between optical components, and to adjust the image position, the entire optical device is moved instead of the mirror to adjust the scanning line position independently. It is desirable to be able to adjust. The present invention has been made in consideration of the above circumstances, and has an object of the following description (O01) in an image forming apparatus using a plurality of optical scanning devices and a plurality of image carriers. (O01) In an optical scanning device for writing an electrostatic latent image by scanning different surfaces to be scanned by the respective laser beams of the two exposure optical systems, by moving the entire optical scanning device,
The position of a scanning line of each of the exposure optical systems can be corrected.

[0008]

Next, the present invention devised to solve the above-mentioned problems will be described. Elements of the present invention are used to facilitate correspondence with elements of the embodiments described later. , The reference numerals of the elements of the embodiment are enclosed in parentheses. The reason why the present invention is described in correspondence with the reference numerals of the embodiments described below is to facilitate understanding of the present invention and not to limit the scope of the present invention to the embodiments.

(1st invention) In order to solve the aforementioned problem,
The image forming apparatus according to the first invention of the present application has the following requirements. (A01) The image forming apparatus is disposed apart from each other in the moving direction of the transfer-receiving member (P) and is arranged apart from the transfer-receiving member (P). ), The first image carrier having a surface to be scanned and a portion of the surface to be scanned which is in contact with the surface of the member to be transferred (P) rotates in the same direction as the member to be transferred (P). 16
k, 16m) and the second image carriers (16y, 16c), (A
02) A light source optical system (Ak) for making a laser beam for image writing incident on the rotating polygon mirror (27) and the rotating polygon mirror (2).
The laser beam reflected from the first image carrier (16) is reflected by the first image carrier (16).
k, 16m) and a scanning optical system (Sk) for scanning in the main scanning direction perpendicular to the sub-scanning direction which is the moving direction of the surface to be scanned, and the first image carrier (16k, 16m). )
A first exposure optical system (Uk, Um) for writing an electrostatic latent image thereon,
(A03) A light source optical system (Ay) for causing a laser beam for image writing to enter the rotary polygon mirror (27), and the laser beam reflected from the rotary polygon mirror (27) is reflected by the second image carrier (1).
6y, 16c) and a scanning optical system (Sy) for scanning in the main scanning direction perpendicular to the sub-scanning direction which is the moving direction of the surface to be scanned, and the second image carrier (16y, 16c).
c) Second exposure optical system (Uy, Uy) for writing an electrostatic latent image on
c), (A04) The laser beam incident directions of the first exposure optical system (Uk, Um) and the second exposure optical system (Uy, Uc) when they enter the surface to be scanned are set to be non-parallel. The first exposure optical system (Uk, Um) and the second exposure optical system (Uy, Uc), and (A05) the first exposure optical system (Uk, Um).
m) and the second exposure optical system (Uy, Uc) are fixedly supported with each other, and each of the image carriers (16k, 16k) is fixed.
y; Exposure optical system support members (H1, H2) capable of moving forward and backward with respect to 16m, 16c).

(Operation of the First Invention)
In the image forming apparatus of the present invention, the first image carriers (16k, 16k) that are arranged apart from each other in the moving direction of the transfer target member (P).
m) and the second image carrier (16y, 16c) have a surface to be scanned in contact with the surface of the member to be transferred (P). The contact portion of the scanned surface with the surface of the member to be transferred (P) rotates in the same direction as the member to be transferred (P). The light source optical system (Ak) of the first exposure optical system (Uk, Um) causes a laser beam for image writing to be incident on the rotary polygon mirror (27). First
The scanning optical system (Sk) of the exposure optical system (Uk, Um) converges the laser light reflected from the rotary polygon mirror (27) on the first image carrier (16k, 16m) and scans the scanning surface. The electrostatic latent image is written on the surface to be scanned on the first image carrier (16k, 16m) by scanning in the main scanning direction perpendicular to the sub-scanning direction, which is the moving direction of. Second exposure optical system (Uy, Uc)
The light source optical system (Ay) makes a laser beam for writing an image incident on the rotary polygon mirror (27). Second exposure optical system (Uy, U
The scanning optical system (Sy) of c) transmits the laser light reflected from the rotary polygon mirror (27) to the second image carrier (16y, 16y).
c) converging upward and scanning in the main scanning direction perpendicular to the sub-scanning direction, which is the direction of movement of the scanned surface, to form an electrostatic latent image on the scanned surface on the second image carrier (16y, 16c). Write the image. Each of the laser beams of the first exposure optical system (Uk, Um) and the second exposure optical system (Uy, Uc) has a non-parallel laser beam incident direction when entering the surface to be scanned. The first exposure optical system (Uk, Um) and the second exposure optical system (U
y, Uc) are fixed to each other, and the exposure optical system support members (H1, H2) support the respective image carriers (16k, 16y; 1).
6m, 16c), the position of the scanning line on the surface to be scanned in the sub-scanning direction can be adjusted.

(Second Invention) An image forming apparatus according to a second invention of the present application has the following requirements.
(B01) The transfer target member (P) which is disposed apart from each other in the movement direction of the transfer target member (P) and has a surface to be scanned in contact with the surface of the transfer target member (P).
A first image carrier (16k, 16m) whose contact portion with the surface rotates and moves in the same direction as the transfer-receiving member (P);
Image carrier (16y, 16c), (B02) rotating polygon mirror (2
7) the laser light reflected from the rotary polygon mirror (27) and the light source optical system (Ak) for making the laser light for image writing incident on the first image carrier (16k, 16m). A scanning optical system (Sk) for scanning in the main scanning direction perpendicular to the sub-scanning direction, which is the direction of movement of the surface to be scanned, wherein a first electrostatic latent image is written on the first image carrier (16k, 16m); (1) Exposure optical system (Uk, Um), (B03) Light source optical system (Ay) for making laser light for image writing incident on rotary polygon mirror (27), and laser light reflected from rotary polygon mirror (27) A scanning optical system (Sy) for converging on the second image carrier (16y, 16c) and scanning in a main scanning direction perpendicular to a sub-scanning direction which is a moving direction of the surface to be scanned;
A second exposure optical system (Uy, Uc) for writing an electrostatic latent image on the second image carrier (16y, 16c); (B04) a first exposure optical system (Uk, Um) and a second exposure optical system (Uy, U
c) the first exposure optical system (U) in which the laser beam incident direction when each laser beam is incident on the surface to be scanned is set to be non-parallel;
k, Um) and the second exposure optical system (Uy, Uc), (B05)
The first exposure optical system (Uk, Um) and the second exposure optical system (Uy, Uc) are supported in a fixed state, and the rotational positions around the skew correction axes (H1a, H2a) parallel to the sub-scanning direction. Adjustable exposure optical system support members (H1, H
2).

(Operation of the Second Invention) In the image forming apparatus according to the second invention of the present application having the above configuration, the first exposure optical system (Uk, Um) and the second exposure optical system (Uy, Uc) are used. Exposure optical system support members (H1, H2) fixedly supported to each other
Are skew correction axes (H1a, H1a) parallel to the sub-scanning direction.
2a) The skew of the scanning line on the surface to be scanned can be corrected by adjusting the rotation position around the scanning position.

(Third Invention) An image forming apparatus according to a third invention of the present application has the following requirements.
(C01) The transferred member (P) which is disposed apart from each other in the movement direction of the transferred member (P) and has a surface to be scanned which comes into contact with the surface of the member to be transferred (P).
A first image carrier (16k, 16m) whose contact portion with the surface rotates and moves in the same direction as the transfer-receiving member (P);
Image carrier (16y, 16c), (C02) rotating polygon mirror (2
7) the laser light reflected from the rotary polygon mirror (27) and the light source optical system (Ak) for making the laser light for image writing incident on the first image carrier (16k, 16m). A scanning optical system (Sk) for scanning in the main scanning direction perpendicular to the sub-scanning direction, which is the direction of movement of the surface to be scanned, wherein a first electrostatic latent image is written on the first image carrier (16k, 16m); (1) Exposure optical system (Uk, Um), (C03) Light source optical system (Ay) for making laser light for image writing incident on rotary polygon mirror (27), and laser light reflected from rotary polygon mirror (27) A scanning optical system (Sy) for converging on the second image carrier (16y, 16c) and scanning in a main scanning direction perpendicular to a sub-scanning direction which is a moving direction of the surface to be scanned;
A second exposure optical system (Uy, Uc) for writing an electrostatic latent image on the second image carrier (16y, 16c); (C04) a first exposure optical system (Uk, Um) and a second exposure optical system (Uy, U
c) the first exposure optical system (U) in which the laser beam incident direction when each laser beam is incident on the surface to be scanned is set to be non-parallel;
k, Um) and the second exposure optical system (Uy, Uc), (C05)
The first exposure optical system (Uk, Um) and the second exposure optical system (Uy, Uc) are supported in a fixed state, and the rotational position can be adjusted around a magnification correction axis (33a) parallel to the main scanning direction. Exposure optical system support members (H1, H2).

(Operation of the Third Invention) In the image forming apparatus of the third invention of the present application having the above configuration, the first exposure optical system (Uk, Um) and the second exposure optical system (Uy, Uc) are used. Exposure optical system support members (H1, H2) fixedly supported to each other
By adjusting the rotation position about the magnification correction axis (33a) parallel to the main scanning direction, the magnification of the scanning line on the surface to be scanned can be corrected.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment of the First Invention) An image forming apparatus according to a first embodiment of the first invention is characterized in that the image forming apparatus of the first invention has the following requirements (A06) 1.
The first exposure optical system (Uk, Um) and the second exposure optical system (Uy, Uc) sharing the rotating polygon mirror (27). (Operation of First Embodiment of First Invention) In the image forming apparatus of the first embodiment of the first invention, the first exposure optical system (Uk,
Um) and the second exposure optical system (Uy, Uc) share one rotating polygon mirror (27). As described above, the first invention is
The first exposure optical system (Uk, Um) and the second exposure optical system (U
y, Uc) are fixed to each other by exposure optical system support members (H1, H2), and move the position of the exposure optical system support members (H1, H2) in the distance direction with respect to the image carrier. The lead register (position of the scanning line in the sub-scanning direction) is adjusted by moving forward and backward. Therefore, even if one rotary polygon mirror (27) is shared, if the positioning of each optical component is first accurately performed, the positional relationship of each optical component does not change when the lead registration position is adjusted. For this reason, even if the first exposure optical system (Uk, Um) and the second exposure optical system (Uy, Uc) share one rotary polygon mirror (27), the position of the optical component may be deviated when the lead registration position is adjusted. No problems arise. By sharing the rotary polygon mirror (27) between the first exposure optical system (Uk, Um) and the second exposure optical system (Uy, Uc), it is possible to reduce the number of necessary rotary polygon mirrors (27). Therefore, the manufacturing cost of the image forming apparatus can be reduced.

(Embodiment 2 of the First Invention) An image forming apparatus according to a second embodiment of the present invention includes the first invention or the first embodiment.
(A07) The image forming apparatus according to Embodiment 1 of the present invention has the following requirements. (A07) The moving direction of the exposure optical system support member (H1, H2) is the first exposure optical system (H07). Uk, Um) and the exposure optical system support members (H1, H2) which are set in parallel with the laser light incident direction of one of the laser light of the second exposure optical system (Uy, Uc) to the surface to be scanned. (Operation of Second Embodiment of the Invention) In the image forming apparatus of the second embodiment of the present invention, the exposure optical system support members (H1, H2)
Is applied to the surface to be scanned from a direction parallel to a direction in which one of the laser light of the first exposure optical system (Uk, Um) and the second exposure optical system (Uy, Uc) is incident on the surface to be scanned. Move forward and backward. Therefore, when the exposure optical system support members (H1, H2) are moved forward and backward, the lead register (the position of the scanning line on the surface to be scanned in the sub-scanning direction) of the one laser beam does not change, and the other laser beam does not change. Only the light lead register (the position of the sub-scanning line of the scanning line) can be adjusted. Therefore, it is easy to adjust the difference between the lead registrations of the two laser beams.

(Embodiment 3 of the First Invention) An image forming apparatus according to a third embodiment of the present invention has the following requirements in the image forming apparatus of the second embodiment of the first invention. (A08) The first exposure optical system (Uk, Um) and the second exposure optical system (Uk, Um) in which the direction of incidence of the one laser beam on the surface to be scanned is set perpendicular to the surface to be scanned. Uy, Uc). (Operation of Embodiment 3 of the First Invention) In the image forming apparatus according to the embodiment 3 of the first invention, the one laser beam is incident on the surface to be scanned from a direction perpendicular to the surface to be scanned. Therefore, the exposure optical system support members (H1, H2) are
An exposure optical system (Uk, Um) and a second exposure optical system (Uy,
Uc) moves forward and backward from the direction of incidence of one laser beam on the surface to be scanned (the direction perpendicular to the surface to be scanned). The image forming apparatus according to the third embodiment of the first invention has the same operation as the second embodiment of the first invention.

(Embodiment 1 of the Second Invention) An image forming apparatus according to a first embodiment of the second invention is characterized in that the image forming apparatus of the second invention has the following requirements.
(B06) The first one sharing one rotating polygon mirror (27)
An exposure optical system (Uk, Um) and a second exposure optical system (Uy,
Uc). (Operation of the First Embodiment of the Second Invention) In the image forming apparatus of the first embodiment of the second invention, the first exposure optical system (Uk,
Um) and the second exposure optical system (Uy, Uc) share one rotating polygon mirror (27). As described above, the second invention
The first exposure optical system (Uk, Um) and the second exposure optical system (U
y, Uc) are fixedly supported by the exposure optical system support members (H1, H2), and correct the position of the exposure optical system support members (H1, H2) in parallel with the sub-scanning direction. The skew of the scanning line on the surface to be scanned is corrected by adjusting the rotational position about the axis (H1a, H2a). Therefore, even if one rotary polygon mirror (27) is shared, if the positioning of each optical component is first accurately performed, the positional relationship of each optical component does not change during the skew correction. Therefore, the first exposure optical system (Uk, Um) and the second exposure optical system (Uk, Um)
Even if the exposure optical system (Uy, Uc) shares one rotating polygon mirror (27), there is no problem due to the displacement of the optical components during the skew correction. By sharing the rotary polygon mirror (27) between the first exposure optical system (Uk, Um) and the second exposure optical system (Uy, Uc), it is possible to reduce the number of necessary rotary polygon mirrors (27). Therefore, the manufacturing cost of the image forming apparatus can be reduced.

(Second Embodiment of the Second Invention) An image forming apparatus according to a second embodiment of the present invention has the following requirements in the image forming apparatus of the first embodiment of the second invention. (B07) The first exposure optical system (Uk, U
m) and the laser light incident direction of each laser light of the second exposure optical system (Uy, Uc) on the surface to be scanned is the rotation axis of each of the image carriers (16k, 16y; 16m, 16c). The first exposure optical system (Uk, Um) and the second exposure optical system (Uy, Uc) which are set substantially symmetrically with respect to a plane which bisects a straight line connecting the vertical and horizontal lines. (Operation of Second Embodiment of Second Invention) In the image forming apparatus of the second embodiment of the second invention, the first exposure optical system (Uk,
Um) and the laser light of the second exposure optical system (Uy, Uc) are substantially parallel to a plane which vertically bisects a straight line connecting the rotation axes of the image carriers (16k, 16y; 16m, 16c). The light enters each of the scanned surfaces from symmetric directions. In this case, when the skew is corrected, the correction amount of the skew becomes substantially equal on each of the image carriers (16k, 16y; 16m, 16c). That is, the change in the position of each scanning line becomes substantially equal, so that the skew correction becomes easy. Further, since the change in the position of each scanning line is uniformed, one of the scan lines does not become extremely large as compared with the other, so that it is possible to prevent the beam diameter from becoming extremely large. Therefore, the change in the distance between the exposure optical system support members (H1, H2) and the surfaces to be scanned during the skew correction can be made substantially equal, thereby minimizing the deterioration of the optical characteristics of the laser light. Can be.

(Embodiment 3 of the Second Invention) An image forming apparatus according to a third embodiment of the present invention is characterized in that the image forming apparatus of the second invention has the following requirements.
(B08) One of the first exposure optical system (Uk, Um) and the second exposure optical system (Uy, Uc) has the laser beam incident on the surface to be scanned perpendicular to the surface to be scanned. The first exposure optical system (Uk, Uk, which is set and the other laser beam incident direction is set in a direction inclined from a direction perpendicular to the surface to be scanned.
Um) and the second exposure optical system (Uy, Uc), (operation of the third embodiment of the second invention) In the image forming apparatus of the third embodiment of the second invention, the first exposure optical system (Uk, Um) ) And the laser light of one of the second exposure optical systems (Uy, Uc) is perpendicularly incident on the surface to be scanned, and the other is incident from an inclined direction. In this case, when the skew is corrected, the skew hardly changes on the image carrier on which the laser beam is incident perpendicularly to the surface to be scanned, but the skew changes on the image carrier on which the laser beam is incident from an inclined direction. Therefore, the skew of the other scanning line can be corrected by using the scanning line on the scanned surface of the image carrier on which the skew does not change as the reference scanning line.

(Embodiment 4 of the Second Invention) An image forming apparatus according to a fourth embodiment of the present invention is characterized in that the image forming apparatus of the second invention has the following requirements.
(B09) A lead registration sensor for detecting a lead registration of a line image on a projection line of a skew correction axis (H1a, H2a) perpendicular to the transfer-receiving member (P). (Operation of the Fourth Embodiment of the Second Invention) In the image forming apparatus according to the fourth embodiment of the second invention, the lead registration sensor includes a skew correction axis (H1a, H2a) perpendicular to the member (P) to be transferred. The lead registration of the line image on the proper projection line is detected. In this case, since the read registration position of the scanning line detected at the read registration detection position does not change even by the skew correction, the skew correction and the read registration can be corrected independently.

(Embodiment 1 of the Third Invention) An image forming apparatus according to a first embodiment of the third invention is characterized in that the image forming apparatus of the third invention has the following requirements.
(C06) The first one sharing one rotating polygon mirror (27)
An exposure optical system (Uk, Um) and a second exposure optical system (Uy,
Uc). (Operation of the First Embodiment of the Third Invention) In the image forming apparatus of the first embodiment of the third invention, the first exposure optical system (Uk,
Um) and the second exposure optical system (Uy, Uc) share one rotating polygon mirror (27). As described above, the third invention is:
The first exposure optical system (Uk, Um) and the second exposure optical system (U
y, Uc) are fixedly supported by the exposure optical system support members (H1, H2), and the rotational position of the exposure optical system support members (H1, H2) is set to a magnification parallel to the main scanning direction. The magnification of the scanning line on the surface to be scanned is corrected by adjusting around the correction axis (33a). Therefore, 1
Even if the plurality of rotary polygon mirrors (27) are shared, if the positioning of each optical component is first accurately performed, the positional relationship of each optical component does not change during magnification correction. For this reason, even if the first exposure optical system (Uk, Um) and the second exposure optical system (Uy, Uc) share one rotating polygon mirror (27), there is a problem due to the displacement of the optical components during magnification correction. No points occur. By sharing the rotary polygon mirror (27) between the first exposure optical system (Uk, Um) and the second exposure optical system (Uy, Uc), it is possible to reduce the number of necessary rotary polygon mirrors (27). Therefore, the manufacturing cost of the image forming apparatus can be reduced.

[0023]

Next, specific examples (embodiments) of the embodiment of the image forming apparatus of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. (Embodiment 1) FIG. 1 is an overall explanatory view of an image forming apparatus (tandem digital color copying machine) according to Embodiment 1 of the present invention. FIG. 2 is an explanatory view of the optical scanning device shown in FIG. 1, FIG. 2A is a plan view as viewed from an arrow IIA in FIG. 2B, and FIG. 2B is an enlarged view of a main part of FIG. FIG. 3 is an explanatory view of the support structure of the exposure system support member shown in FIG. 1 and 2, a tandem digital color copying machine F as an image forming apparatus has a UI (user interface) having a copy start button, a numeric keypad, a display unit, and the like on an upper part thereof.
And a transparent platen glass 2 on which the original 1 is placed. A document illumination unit 3 that scans the document 1 while illuminating the document 1 is arranged below the platen glass 2. The document illumination unit 3 has a document illumination light source 4 and a first mirror 5. A mirror unit 6 that moves at half the speed of the original illumination unit 3 is disposed below the platen glass 2. The mirror unit 6 has a second mirror 7 and a third mirror 8 which are emitted from the illumination light source 4 and reflected by the original 1 and reflect original image light reflected by the first mirror 5. The document image light reflected by the third mirror 8 passes through the imaging lens 9 and is read as R, G, and B analog signals by a CCD (color image reading sensor).

The R (red), G (green), and B (blue) image signals read by the CCD are input to the IPS.
The operation of the IPS is controlled by the controller C.
Further, the IPS converts the analog electric signals of the R, G, B read images obtained by the CCD into digital signals and outputs the digital signals, and outputs the RGB image data to K (black), Y (Y). (Yellow), M (magenta), and C (cyan) image data that is converted into image data, subjected to data processing such as density correction and enlargement / reduction correction, and output as writing image data (laser drive data) Means 12 are provided. The image data output unit 1
2 has an image memory 13 for temporarily storing the KYMC image data.

The IPS write image data output means 12
Output the KYMC four-color image writing data (laser drive data) output by the laser drive signal output devices 14k, 14y, 14m, and 14c of the respective colors K, Y, M, and C. Is input to The laser drive signal output devices 14k, 14y, 14m, and 14c for each color are
It has a function of outputting a laser drive signal corresponding to the input image data to the optical scanning device U at a predetermined timing. The optical scanning device U has a KY optical scanning device U1 for writing K and Y images, and an MC optical scanning device U2 for writing M and C images.

The optical scanning device U1 for KY has a first exposure optical system (K exposure optical system) Uk for forming electrostatic latent images of K (black) and Y (yellow) on the image carriers 16k and 16y, respectively. Second exposure optical system (Y exposure optical system) Uy
have. The optical scanning device U2 for MC is M
A first exposure optical system (M exposure optical system) Um and a second exposure optical system (C exposure optical system) for forming electrostatic latent images of (magenta) and C (cyan) on the image carriers 16m and 16c, respectively. Uc. Around the image carrier 16k on which a black image is formed, a charger 17k, a developing device 18k,
A cleaner 19k and the like are arranged. Then, the same chargers 17y, 17m, 1 around the image carrier 16k are also provided around the other image carriers 16y, 16m, 16c.
7c, developing devices 18y, 18m, 18c, cleaner 19y,
19m, 19c, etc. are arranged. The developing device 18
k, 18y, 18m, 18c are image carriers 16k, 16y, 1
This device develops the electrostatic latent images on 6m and 16c into toner images of K (black), Y (yellow), M (magenta), and C (cyan) colors.

KY having the exposure optical systems Uk and Uy
The optical scanning device U1 for KY and the optical scanning device U2 for MC having the above-mentioned exposure optical systems Um and Uc are configured in the same manner, and the optical scanning device U1 for KY will be described with reference to FIG. In FIG. 2, the first exposure optical system Uk and the second exposure optical system Uy of the KY optical scanning device U1 each have a semiconductor laser light source 21. Each semiconductor laser light source 21
The laser beams Lk and Ly emitted from the laser beam pass through the collimator lens 22 and the spherical lens 23 and enter the mirror 24. The laser beams Lk and Ly reflected by the mirror 24 pass through the Fθ lens 26 and enter the rotary polygon mirror 27. The light source optical systems Ak and Ay are constituted by the elements indicated by the reference numerals 21 to 27. The laser beams Lk and Ly reflected by the rotary polygon mirror 27 pass through the Fθ lens 26, are reflected by a mirror 28, and enter a cylindrical mirror 29. The cylindrical mirror 29 is a member having a cylindrical reflecting surface for correcting tilting of the rotary polygon mirror 27,
The incident laser beams Lk and Ly are respectively transmitted to the image carriers 16k and 16k.
It converges on the surface (scanned surface) of 16y. Code 26
Scanning optical systems (optical systems for scanning the surface to be scanned on the surface of the image carrier with laser light in the main scanning direction (axial direction of the image carrier)) Sk and Sy (see FIG. 2B). Is configured. The exposure optical systems Uk and Uy are constituted by the elements indicated by the reference numerals 21 to 29.

The exposure optical systems Uk and Uy are supported by the same exposure optical system support member H1. The exposure optical system support member H1 is a box-shaped member as shown in FIG.
A shaft support block 32 is fixedly supported on the lower surface of an elevating block 31 which is moved up and down by an elevating device (not shown) in FIG. 3, and a magnification correction shaft 33a fixed to a rotating member 33 is rotatable on the shaft support block 32. It is supported by. A driven gear 34 is fixedly supported on the magnification correction shaft 33a. A skew correction shaft H1a fixed to the exposure optical system support member H1 is rotatably supported by the rotation member 33. A driven gear 35 is fixed to the shaft skew correction shaft H1a. The axis 33a is arranged parallel to the axis of the image carriers 16k and 16y (parallel to the main scanning direction). The axis H1a is arranged parallel to a sub-scanning direction perpendicular to the main scanning direction.

The elevating block 31 is moved up and down by a not-shown elevating device (lead register adjusting device).
The exposure optical system support member H1 moves in the distance direction with respect to the image carriers 16k and 16y. The driven gear 34 fixed to the magnification correction shaft 33a is driven to rotate by a magnification adjustment motor (not shown). At this time, the magnification correction shaft 33a, the rotation member 33, and the exposure optical system support member H1 rotate around an axis parallel to the main scanning direction. The skew correction axis H
The gear 35 fixed to 1a is driven to rotate by a skew correction motor (not shown). At this time, the exposure optical system support member H1 is driven to rotate around an axis parallel to the sub-scanning direction. The KY optical scanning device U1 is composed of the exposure optical systems Uk and Uy, the exposure optical system support member H1 that supports them, and the elements indicated by the reference numerals 31 to 35.

The exposure optical systems Um and Uc are also the same as the exposure optical system Uk and Uy.
And the exposure optical system support member H2.
Is a lifting block 3 similar to the exposure optical system support member H1.
1, shaft support block 32, rotating member 33, magnification correction shaft 3
3a, driven gear 34, gear 35, skew correction shaft H2a
(Not shown) and the like, the movement in the perspective direction with respect to the image carriers 16m and 16c, the adjustment of the rotational position around the magnification correction axis 33a, the skew correction around the skew correction axis H2a (not shown), and the like are performed. Have been. The MC optical scanning device U2 is constituted by the exposure optical systems Um and Uc, the exposure optical system support member H2 that supports them, and the elements indicated by the reference numerals 31 to 35. The K
The optical scanning device U1 for Y and the optical scanning device U2 for MC are
Each of them is configured using the same parts, and the parts can be shared, so that the manufacturing cost can be reduced.

Each color exposure optical system U of the optical scanning device U
k, Uy, Um, Uc are the laser drive signal output devices 14
k, Y, input from k, 14y, 14m, 14c
According to the laser drive signals of the respective colors M and C, the charger 1
An electrostatic latent image is written on the image carriers 16k, 16y, 16m, and 16c uniformly charged by 7k, 17y, 17m, and 17c. The electrostatic latent images on the image carriers 16k, 16y, 16m, and 16c are converted to K by developing devices 18k, 18y, 18m, and 18c.
(Black), Y (yellow), M (magenta), and C (cyan) are developed into toner images of respective colors.

The image carriers 16k, 16y, 16m, 16c
A transfer material transporting device H is disposed below. The transfer material transport device H has the belt module B shown in FIG. The belt module B includes a belt supporting drive roll 41, a peeling roll 42, a tension roll 43, and an idler rotatably supported by front and rear plates (not shown) provided at both ends in the front-rear direction (X-axis direction). It has a roll 44. A belt 45 for transferring the transfer material is supported by the rolls 41 to 44. Upper surface of the belt 45 (image carrier 16
k, 16y, 16m, and 16c) are horizontally arranged. A driven gear (not shown) is mounted on the rear end of the driving roll 41, and is configured to transmit a rotational driving force.

Each of the image carriers 16k, 16y, 16m, 1
The transfer device 46 is located at the transfer position where the belt 6c and the belt 45 contact.
k, 46y, 46m, and 46c are arranged. A peeling corotron 47 is arranged on the upstream side of the peeling roll 42,
A stripper (peeling claw) 48 is arranged on the downstream side. A fixing device 49 is disposed on the left side of the belt 45, and the tension roll 43 and the driving roll 41
A belt cleaner 50 for collecting toner adhered to the surface of the belt 45 is disposed between the belt cleaner 50 and the belt cleaner 50. In FIG. 1, a transfer target member (paper) P is accommodated in a paper feed cassette 51 disposed below the transfer material transport device H. The transferred member P is taken out by the transfer material take-out roll 52 and transported to the registration roll 53. The registration roller 53 conveys the conveyed transferred member P to a transfer material suction position between the belt 45 and the suction roll 54 at a predetermined timing. The suction roll 54 is used to transfer the transferred member P.
Is pressed against the belt module B to be adsorbed.

The transferred member P attracted to the belt 45 at the transfer material attracting position is conveyed by the belt 45. At this time, the image forming start position on the member P to be transferred conveyed by the belt 45 and the K (black) image on the K (black) image carrier 16k disposed on the most upstream side in the transfer material conveying direction are determined. The transfer timing of the transfer target member P and the image writing timing are determined so that the leading end coincides with the transfer point between the transfer unit 46k and the image carrier 16k. The toner image on the image carrier 16k is transferred by the transfer device 46k to the transfer target member P that has reached the transfer point. This K
The transfer member P to which the (black) toner image has been transferred is sequentially transferred to the image carriers 16y, 16m, and 16c and the transfer units 46y, 46m, and 46c.
Is transferred to the transfer point between
The image writing timing of y, 16m, and 16c is K (black) in which the leading end of each of the Y, M, and C toner images is transferred to the transfer target member P.
Is determined so as to coincide with the tip of the toner image.

The transfer member P on which the toner images of the respective colors are transferred is separated from the peeling corotron 47 and the stripper 48.
The toner is peeled at a peeling point on the outer periphery of the peeling roller 42, and is conveyed to the fixing device 49. The transfer-receiving member P on which the color toner image is fixed by the fixing device 49 is a discharge roll 55
From the discharge tray TR. The image carriers 16k, 16y, 16m, 16c after the transfer of the toner image are performed.
The surface is cleaned by cleaners 19k, 19y, 19m and 19c.

In the multi-transfer type image forming apparatus U for sequentially transferring a plurality of toner images onto a transfer material, writing of toner images of each color on each transfer member P in the main scanning direction and the sub-scanning direction. If the start position is shifted, a color shift occurs and the image quality deteriorates. Therefore, light sources 56, 56, and 5 for detecting the positional deviation of the scanning line are provided at a position on the downstream side of the optical scanning device Uc of the belt 45 at the center and both ends in the belt width direction.
6 (only one is shown in FIG. 1) and image position sensors 57, 57, 57 are arranged corresponding to the light sources 56. The light source 56 and the image position sensor 57 opposed to the light source 56 disposed at the central portion in the belt width direction detect a lead register of a line image on the projection line of the skew correction axes H1a and H2a perpendicular to the transfer target member P. . That is, the light source 56 disposed at the center in the belt width direction
Is used as the lead registration sensor 57. The image position sensors 57, 57 facing the light sources 56, 56 arranged at both ends in the belt width direction are used as skew sensors. An image position signal 57a output from the image position sensor 57
Is input to the controller C so that the writing start timing of each of the laser drive signal output devices 14k, 14y, 14m, and 14c is adjusted.

(Operation of Embodiment 1) FIG. 4 is an explanatory diagram of a lead registration correcting method according to Embodiment 1 of the present invention. In FIG. 4, scanning lines Lk, Lk on the scanned surface (the surfaces of the image carriers 16k, 16y) when the exposure optical system support member H1 is at the solid line position are shown.
When the exposure optical system support member H1 moves to a position away from the surface to be scanned (see a two-dot chain line), Lk 'and Lk become Ly.
y '. That is, the position (lead registration) of the scanning line on the surface to be scanned in the sub-scanning direction can be adjusted by moving the exposure optical system support member H1 in the distance direction with respect to the image carriers 16k and 16y. The adjustment of the lead register is performed using both the adjusting method shown in FIG. 4 and the method of adjusting the writing scan timing by laser light.

FIG. 5 is an explanatory diagram of a magnification correction method according to the first embodiment of the present invention. In FIG. 5, the exposure optical system support member H1
To be scanned (image carrier 16k, 1)
The scanning lines Lk and Ly on the (6y surface) become Lk 'and Lk when the exposure optical system support member H1 rotates around the magnification correction axis 33a.
y '. That is, the exposure optical system support member H1 is rotated so that the exposure optical system Uk supported by the exposure optical system support member H1 is far away from the image carrier 16k, and the exposure optical system Uy approaches the image carrier 16y. In this case, the scanning line Lk becomes a longer scanning line Lk ', and the scanning line Ly becomes a shorter scanning line Ly'. That is, by rotating the exposure optical system support member H1 about the magnification correction axis 33a, the magnification (length) of the scanning line in the main scanning direction can be corrected. For the correction of the magnification, it is also possible to use a method of adjusting the writing scanning timing by laser light in addition to the method shown in FIG.

FIG. 6 is an explanatory diagram of a skew correction method according to the first embodiment of the present invention. In FIG. 6, when the exposure optical system support member H1 is at the solid line position, the surface to be scanned (the image carrier 16k,
The scanning lines Lk and Ly on the (16y surface) become L when the exposure optical system support member H1 rotates around the skew correction axis H1a.
k 'and Ly'. That is, the exposure optical system support member H1
Image carriers 16k, 16k of the exposure optical system Uk supported by
Rotate so that one end in the axial direction of y is far away and the other end approaches the image carriers 16k and 16y (skew correction axis H
When the scanning lines Lk and Ly rotate on the image carriers 16k and 16y, the scanning lines Lk and Ly open at one end outward and narrow at the other end. That is, when the exposure optical system support member H1 rotates around the skew correction axis H1a, the scanning line L
k and Ly become the scanning lines Lk 'and Ly', and the skew of the scanning lines can be corrected.

(Embodiment 2) FIG. 7 is an explanatory view of Embodiment 2 of the image forming apparatus of the present invention. In the description of the second embodiment, components corresponding to the components of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.
The second embodiment differs from the first embodiment in the following points, but has the same configuration as the first embodiment in other points. Each of the scanning optical systems Sk and Sy has another flat folding mirror 30 between the mirror 28 and the cylindrical mirror 29. The respective cylindrical mirrors 29 of the scanning optical systems Sk and Sy reflect their reflected light in directions away from each other in the first embodiment.
In the second embodiment, the light is reflected in directions approaching each other.
The second embodiment also has the same operation as the first embodiment.

(Embodiment 3) FIG. 8 is an explanatory view of Embodiment 3 of the image forming apparatus of the present invention. In the description of the third embodiment, components corresponding to the components of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.
The third embodiment differs from the first embodiment in the following points, but has the same configuration as the first embodiment in other points. In the third embodiment, the image carrier 16 of the laser light emitted from the Y exposure optical system supported by the exposure optical system support member H1 is used.
The direction of incidence on y and the direction of movement of the exposure optical system support member H1 are set in parallel. The incident direction of the laser beam on the image carrier 16y is set perpendicular to the surface (scanned surface) of the image carrier 16y. The incident direction of the laser beam from the K exposure optical system supported by the exposure optical system support member H1 to the image carrier 16k is inclined with respect to the moving direction of the exposure optical system support member H1. Example 3 having the above configuration is
The scanning lines on the surface to be scanned when the exposure optical system support member H1 is at the position indicated by the solid line are indicated by Lk and Ly. In this state, the exposure optical system support member H1 is moved upward (the image carrier 16k, 1).
The scanning line when it is displaced to the position indicated by the two-dot chain line by moving in the direction of the perspective with respect to 6y is Lk ′, Ly ′ indicated by the two-dot chain line. In this case, the scanning line Ly does not move in the sub-scanning direction,
Only Lk moves in the sub-scanning direction. That is, the position (lead registration can be adjusted) of Lk in the sub-scanning direction, using Ly as a reference line of the scanning line.

(Embodiment 4) FIG. 9 is an explanatory view of Embodiment 4 of the image forming apparatus of the present invention. In the description of the fourth embodiment, the same reference numerals are given to the components corresponding to the components of the first embodiment, and the detailed description thereof will be omitted.
The fourth embodiment differs from the first embodiment in the following points, but has the same configuration as the first embodiment in other points. In FIG. 9, the K exposure optical system Uk and the Y exposure optical system Uy for irradiating a laser beam on the image carriers 16k and 16y are the same as those in the first embodiment in that the rotary polygon mirror 27 is shared. The reflection direction of the laser light from the rotary polygon mirror 27 is the opposite direction in the first embodiment, whereas it is the opposite direction in the first embodiment. Although not shown in FIG. 9, the exposure optical system support member H1 in FIG. 9 is formed by the members indicated by reference numerals 31 to 35 in FIG.
It is supported so that it can move forward and backward with respect to k and 16y to adjust its position, adjust its rotational position about an axis H1a parallel to the sub-scanning direction, and adjust its rotational position about a parallel axis 33a in the main scanning direction. I have. In the fourth embodiment, similarly to the first embodiment, correction of the lead registration, skew, and magnification can be performed.

(Embodiment 5) FIG. 10 is an explanatory view of Embodiment 5 of the image forming apparatus of the present invention. In the description of the fifth embodiment, the same reference numerals are given to the components corresponding to the components of the first embodiment, and the detailed description is omitted. The fifth embodiment differs from the first embodiment in the following points, but has the same configuration as the first embodiment in other points. In FIG. 10, the K exposure optical system Uk and the Y exposure optical system Uy for irradiating a laser beam on the image carriers 16k and 16y respectively have different rotary polygon mirrors 27. Although illustration is omitted in FIG. 10 similarly to FIG. 9 of the fourth embodiment, in the fifth embodiment, similarly to the first and fourth embodiments, it is possible to correct the lead registration, skew, and magnification. It is configured to be able to.

[0044]

The above-described image forming apparatus of the present invention has the following effects. (E01) In an optical scanning device for writing an electrostatic latent image by scanning different scanning surfaces with respective laser beams of two exposure optical systems, by moving the entire optical scanning device,
The displacement of the scanning line of each of the exposure optical systems can be corrected.

[Brief description of the drawings]

FIG. 1 is an overall explanatory diagram of an image forming apparatus (tandem-type digital color copying machine) according to a first embodiment of the present invention.

2 is an explanatory view of the optical scanning device shown in FIG. 1; FIG. 2A is a plan view as viewed from an arrow IIA in FIG. 2B; and FIG. 2B is an enlarged view of a main part of FIG.

FIG. 3 is an explanatory view of a support structure of the exposure system support member shown in FIG. 1;

FIG. 4 is an explanatory diagram of a lead registration correction method according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram of a magnification correction method according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram of a skew correction method according to the first embodiment of the present invention.

FIG. 7 is an explanatory diagram of Embodiment 2 of the image forming apparatus of the present invention.

FIG. 8 is an explanatory diagram of Embodiment 3 of the image forming apparatus of the present invention.

FIG. 9 is an explanatory view of Embodiment 4 of the image forming apparatus of the present invention.

FIG. 10 is a diagram illustrating an image forming apparatus according to a fifth embodiment of the present invention.
FIG.

FIG. 11 is an explanatory diagram of a positional shift of a line image formed by scanning lines on a surface to be scanned by a plurality of laser beams.

[Explanation of symbols]

Ak: light source optical system, Ay: light source optical system, H1, H2: exposure optical system support member, H1a, H2a: skew correction axis, P: transferred member, Sy: scanning optical system, Sk: scanning optical system, Uy, Uc
... Second exposure optical system, Uk, Um ... First exposure optical system, 27 ...
Rotating polygon mirror, 33a ... magnification correction axis, (16k, 16m) ...
A first image carrier, (16y, 16c) ... a second image carrier,

Claims (3)

[Claims] 1. An image forming apparatus having the following requirements: (A01) A scanning surface which is arranged apart from each other in a moving direction of a member to be transferred and contacts a surface of the member to be transferred. A first image bearing member and a second image bearing member having a contact portion of the scanned surface with the surface of the member to be transferred, which rotates in the same direction as the member to be transferred; (A02) image writing on a rotating polygon mirror A laser light reflected from the rotary polygon mirror and a light source optical system for inputting laser light for use in the main scanning direction perpendicular to a sub-scanning direction, which is a moving direction of the surface to be scanned, by converging the laser light on the first image carrier. A first exposure optical system for writing an electrostatic latent image on the first image carrier, and a light source optical system for making a laser beam for writing an image incident on a rotating polygon mirror (A03) And the laser light reflected from the rotating polygon mirror is used as the second image A scanning optical system that converges on a carrier and scans in a main scanning direction perpendicular to a sub-scanning direction that is a moving direction of the surface to be scanned, and writes an electrostatic latent image on the second image carrier. 2-exposure optical system, (A04) the first exposure optical system in which the laser beam incident directions of the laser light of the first exposure optical system and the second exposure optical system upon incidence on the surface to be scanned are set to be non-parallel. And a second exposure optical system, (A05) an exposure optical system support member that supports the first exposure optical system and the second exposure optical system in a fixed state, and is capable of moving forward and backward with respect to each of the image carriers. . 2. An image forming apparatus having the following requirements: (B01) a scanning surface which is arranged apart from each other in a moving direction of a member to be transferred and contacts a surface of the member to be transferred; A first image carrier and a second image carrier, wherein a contact portion of the scanned surface with the surface of the member to be transferred is rotated in the same direction as the member to be transferred; (B02) image writing on a rotating polygon mirror A laser light reflected from the rotary polygon mirror and a light source optical system for inputting laser light for use in the main scanning direction perpendicular to a sub-scanning direction, which is a moving direction of the surface to be scanned, by converging the laser light on the first image carrier. A first exposure optical system for writing an electrostatic latent image on the first image carrier, and a light source optical system for causing a laser beam for image writing to enter a rotating polygon mirror (B03). And the laser light reflected from the rotating polygon mirror is used as the second image A scanning optical system that converges on a carrier and scans in a main scanning direction perpendicular to a sub-scanning direction that is a moving direction of the surface to be scanned, and writes an electrostatic latent image on the second image carrier. 2-exposure optical system, (B04) the first exposure optical system in which the laser beam incident directions of the laser light of the first exposure optical system and the second exposure optical system upon incidence on the surface to be scanned are set to be non-parallel. And a second exposure optical system, and (B05) an exposure optical system which supports the first exposure optical system and the second exposure optical system in a fixed state and adjusts a rotational position about a skew correction axis parallel to the sub-scanning direction. System support member. 3. An image forming apparatus having the following requirements: (C01) a scanning surface which is arranged apart from each other in a moving direction of a member to be transferred and contacts a surface of the member to be transferred; A first image carrier and a second image carrier, wherein a portion of the scanned surface that comes into contact with the surface of the member to be transferred is rotated in the same direction as the member to be transferred; (C02) image writing on a rotating polygon mirror A laser light reflected from the rotary polygon mirror and a light source optical system for inputting laser light for use in the main scanning direction perpendicular to a sub-scanning direction, which is a moving direction of the surface to be scanned, by converging the laser light on the first image carrier. A first exposure optical system for writing an electrostatic latent image on the first image carrier, and a (C03) light source optical system for causing a laser beam for image writing to be incident on a rotary polygon mirror. And the laser light reflected from the rotating polygon mirror is used as the second image A scanning optical system that converges on a carrier and scans in a main scanning direction perpendicular to a sub-scanning direction that is a moving direction of the surface to be scanned, and writes an electrostatic latent image on the second image carrier. 2-exposure optical system, (C04) the first exposure optical system in which the laser light incident directions of the first exposure optical system and the second exposure optical system when the laser light is incident on the surface to be scanned are set to be non-parallel. And a second exposure optical system, (C05) an exposure optical system that supports the first exposure optical system and the second exposure optical system in a fixed state and that can adjust a rotational position about a magnification correction axis parallel to the main scanning direction. System support member.