JP2979328B2 - Color image forming equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a color image forming apparatus which forms a toner image on an image forming body by an electrophotographic method and transfers the toner image onto a transfer material to obtain an image.

[Prior art]

As an image forming method for obtaining a color image by using an electrophotographic method, for example, JP-A-60-75850, JP-A-60-76766, and JP-A-60-76766.
As disclosed in JP-A-95456, JP-A-60-95458, JP-A-60-158475, etc., latent image formation and development in accordance with the number of colors of an original image are repeated on an image forming body, and There is a method in which a color image is obtained by superimposing and transferring a color toner image. As an image forming apparatus to which the color image forming method is applied, there is an image forming apparatus using a belt-shaped image forming body. This belt-shaped image forming body is stretched between two rotating rollers on a belt-shaped image forming body in which a photoconductor is applied or vapor-deposited on a flexible belt, and driven in a clockwise direction by driving a driven rotating roller. Transport to A tension roller is attached to the belt-shaped image forming member, and the belt-shaped image forming member is configured to rotate while maintaining a slidable contact state with a reference guide member by the tension caused by the pressure contact. The guide member has a portion located on the back surface of the belt-shaped image forming member as a convex curved surface portion, and slides the back surface of the belt-shaped image forming member against the curved surface portion to thereby expose the photosensitive surface of the belt-shaped image forming member. It is set at a predetermined position, and the state is maintained even during conveyance. The curved surface portion, for example, by forming a simple convex surface composed of only one curvature radius R, even when the belt-shaped image forming body is slid contact operation, without giving a large frictional resistance, to uniformly press-contact The belt-shaped image forming body is conveyed at a smooth and stable speed. On the other hand, since the curved surface portion can be a convex surface close to a flat surface by increasing the radius of curvature R, it is possible to arrange image forming means including a developing device and an exposure device in a substantially linear parallel arrangement. In this case, the cost can be reduced by using a common developing unit, and the configuration can be made extremely simple. In addition, only the portions corresponding to the charger, the exposure device, and the developing sleeve have convex surfaces, and the other convex portions can facilitate movement of the belt-shaped image forming body. A charger around the belt-shaped image forming body by the above-described configuration,
2. Description of the Related Art There is provided a color image forming apparatus in which a plurality of image forming means including a developing device and an exposure device are arranged to form a plurality of color toner images during one rotation of a belt-shaped image forming body.

[Problems to be solved by the invention]

However, in the above color image forming apparatus,
In order to reduce the frictional resistance between the guide member and the belt-shaped image forming body when the belt-shaped image forming body is slid and conveyed, for example, the guide member has the same portion located on the back surface of the belt-shaped image forming body. When a plurality of exposure devices are independently arranged around the belt-shaped image forming body, the optical path length from the exposure device to the photosensitive surface of the belt-shaped image forming body is formed. Is different for each of a plurality of exposure apparatuses, it is difficult to guarantee the distance and parallelism between the respective exposure apparatuses, and it is not possible to match latent images of each color in units of tens of μm. To solve this, the optical system of each exposure apparatus must be arranged with high precision. That is, the adjustment for keeping the registration of the scanning light in the main scanning and sub-scanning directions from each exposure device becomes complicated, and the latent images of the respective colors cannot be aligned in tens of μ units, thereby causing a color shift. There is. SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional problems, and it is an object of the present invention to prevent a color shift when a plurality of exposure apparatuses including optical systems designed with the same optical path length are arranged around a belt-shaped image forming body. It is another object of the present invention to provide a color image forming apparatus for the purpose.

[Means for solving the problems]

In order to achieve the above object, the present invention provides two rotating rollers, a belt-shaped image forming member stretched between the rotating rollers, and a convex surface, and the belt-shaped image forming member has a convex surface with respect to the convex surface. A guide member disposed inside the belt-shaped image forming body such that the surface moves while slidingly contacting the belt-shaped image forming body, and at least exposure is performed in opposition to a photosensitive surface of the belt-shaped image forming body that slides on the guide member. In a color image forming apparatus in which a plurality of sets of means and developing means are arranged, the plurality of exposing means are arranged on a single substrate, and the plurality of exposing means are arranged on the belt-shaped image from the convex side of the guide member. The exposure is performed on the formed body, and the exposure light scanned by the plurality of exposure units is exposed on the belt-shaped image formed body with the same exposure length.

【Example】

Next, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing one embodiment of a color image forming apparatus of the present invention, FIG. 2 is a side view showing a process cartridge of this embodiment, and FIG. FIG. 4 is a sectional view showing a state in which an exposure unit is incorporated in the process cartridge of this embodiment. The color image forming apparatus according to the present embodiment forms the toner images of the respective colors in a superimposed manner during one rotation of the belt-shaped image forming body, and includes a paper feed cassette 15, a paper feed roller 16, a registration roller 17, and a transfer device. 18, a cleaning device 19, a process cartridge 30, and an exposure unit 40. Hereinafter, each component of the present embodiment will be described. The process cartridge 30 has a guide member 5 having a curvature between the two rotating rollers 2 and 3. The process cartridge 30 is stretched between the rotating rollers 2 and 3 and moves while slidingly contacting the guide member 5. Body 1, and four sets of chargers 7, 9, and 4 arranged opposite to the photosensitive surface of the belt-shaped image forming body 1 slidably in contact with the guide member 4.
11, 13 and developing units 8, 10, 12, 14 are housed in a housing 30k. The housing 30 </ b> K includes a substantially rectangular image forming body storage section having a curved surface for storing the belt-shaped image forming body 1 and the cleaning device 6, a charger 7, 9, 11, 13, and a developing unit 8, 10, 12, A rectangular unit storage section for storing 14 is integrally formed. The unit storage section has an opening at the bottom and a hole 30a penetrating through the side wall.
30b is formed, and when the exposure unit is fitted,
The stoppers 40c, 40d provided on the exposure unit 40 are locked to 0a, 30b. The belt-shaped image forming body 1 is a belt-shaped photoconductor in which a photoconductor is coated or vapor-deposited on a flexible belt. The sheet is conveyed clockwise by the driving of the moving roller 2. Further, a tension roller 4 is attached to the belt-shaped image forming body 1, and slidably contacts a guide member 5 serving as a reference by the tension caused by the pressure contact. The guide member 5 has a convex curved surface portion in which a portion located on the back surface of the belt-shaped image forming body 1 has the same radius of curvature R. Since the curved surface portion of the guide member 5 can have a large curvature radius R and can be a convex surface close to a flat surface, it is possible to arrange image forming means including a developing device and an exposure device in a substantially straight line in parallel. In this case, the cost can be reduced by using a common developing unit, and the configuration can be made extremely simple. The guide member 5 has a large radius of curvature R at its center and a small radius of curvature r at its ends,
The photoreceptor belt including the guide member has a shape that is shorter in the lateral direction than in the case of the same radius of curvature R, and can be formed compact. With these configurations, the belt-shaped image forming body 1 sets the photosensitive surface at a predetermined position while slidingly contacting the curved surface portion of the guide member 5 by the tension caused by the pressure contact of the tension roller 4, and maintains the state during conveyance. It has become. At this time, since the guide member 5 has a simple convex surface composed of only one radius of curvature R as described above, a large frictional resistance is given even when the belt-shaped image forming body 1 is operated in sliding contact. As a result, the belt-shaped image forming body 1 is transported at a smooth and stable speed. The exposure unit 40 accommodates the exposure devices 41 to 44 having the same configuration in a housing 40k, arranges the laser devices from the exposure devices 41 to 44 so as to irradiate the laser beams in parallel, and adjusts the curvature of the belt-shaped image forming body 1. The polygon mirrors 41a, 42a, 43a, 44 are so designed that the optical path lengths of the laser beams from the respective exposure devices 41 to 44 become the same.
a, the positions of the fθ lenses 41c, 42c, 43c, and 44c are provided horizontally, and the positions of the mirrors 41d, 42d, 43d, and 44d for reflection are adjusted in advance and installed on the housing 40k. The housing 40k includes a rectangular fitting portion that fits into a rectangular portion located below the housing 30k, and a storage portion that stores the exposure devices 41 to 44. The fitting portion and the storage portion are separated by attaching a protective film that transmits light. The fitting part of the housing 40k has a locking member 4 on the side wall.
0a and 40b are provided. The bottom wall of the housing 40k has a step in consideration of the curvature of the curved surface of the belt-shaped image forming body 1, and by installing a mirror on the bottom wall, the exposure surface of each image forming apparatus is exposed from each exposure apparatus. The length of the optical path can be the same. In this embodiment, a pedestal for installing a polygon mirror or the like is provided in the storage unit. In the color image forming apparatus of the present embodiment, the process cartridge 30 or the exposing unit 40 is replaced, and a sectional view when the exposing unit 40 is fitted to the process cartridge 30 is shown in FIG. The engaging members 40a and 40b are engaged with the engagement portions of 40k in the holes 30a and 30b of the process cartridge 30. At this time, due to the structure of the exposure unit 40, the laser light from each of the exposure devices 41 to 44 is irradiated on the curved photosensitive surface of the belt-shaped image forming body 1 in parallel with the same optical path length. In this way, the color image forming apparatus of the present embodiment can easily perform the alignment of the latent images of each color, and can prevent color misregistration. FIG. 5 is a sectional view showing a state in which an exposure unit is incorporated in the process cartridge of the second embodiment. The exposure unit 240 includes polygon mirrors 241a, 242a, 243a,
244a is provided on the coaxial 245, and the optical path difference of each exposure apparatus is adjusted by the position where the reflection mirrors 241b, 241c, 242b, 242c, 243b, 243c, 244b, 244c are arranged, so that the optical path length of each exposure apparatus is the same. That means that FIG. 6 is a sectional view showing a state in which an exposure unit is incorporated in the process cartridge of the third embodiment. The exposure unit 40 accommodates the exposure devices 41 to 44 having the same configuration in a housing 40k, arranges the laser devices from the exposure devices 41 to 44 so as to irradiate the laser beams in parallel, and adjusts the curvature of the belt-shaped image forming body 1. Considering the reflection mirrors 41c, 41d, 42c, 42d, 43c, so that the optical path length of the laser light from each of the exposure devices 41 to 44 becomes the same.
The positions of 43d, 44c, and 44d are provided in common, while the positions of the polygon mirrors 41a, 42a, 43a, and 44a and the fθ lenses 41b, 42b, 43b, and 44b are adjusted to be positions that are corrected in advance, and installed in the housing 40k. It was done. FIG. 7 is a sectional view showing an exposure unit of the fourth embodiment. The exposure unit 40 has substantially the same configuration as the exposure unit shown in FIG. 3, except that a polygon mirror and an fθ lens are provided on the bottom wall via a step to make the optical path length the same. FIG. 8 is a sectional view showing an exposure unit of the fifth embodiment, and FIG. 9 is a sectional view showing a state in which the exposure unit of the fifth embodiment is incorporated in a process cartridge. The exposure unit 140 accommodates exposure devices 141 to 144 each including an LED array and a light-converging lens array in a housing 141k. In the fitting portion of the housing 140k, locking members 140a and 140b are provided on the side wall in the same manner as shown in FIG. In the exposure apparatuses 141 to 144 of this embodiment, a light-converging lens array that forms an image on a one-to-one basis, for example, is arranged in a light-emitting portion of an LED array. One spot is formed on one photosensitive surface. The housing 140k includes a rectangular fitting portion that fits into a rectangular portion located below the housing 30k of the process unit 30, and a storage portion that stores the exposure devices 141 to 144.
A partition wall for partitioning the fitting portion and the storage portion has a wall having the same curvature as the curved surface portion of the belt-shaped image forming body 1 fixed to the bottom of the fitting portion with a screw. A hole is formed in the partition wall so as to penetrate the light converging lens array of the exposure devices 141 to 144.
The optical path length from 141 to 144 to the exposure surface of the belt-shaped image forming body can be the same. Even in the color image forming apparatus of this embodiment, the process cartridge 30 or the exposing unit 140 is replaced, and a cross-sectional view when the exposing unit 140 is fitted to the process cartridge 30 is shown in FIG. The engagement portion of the body 140k is engaged with the holes 30a, 30b of the process cartridge 30 by the locking members 140a,
Lock 140b. At this time, due to the structure of the exposure unit 140, the light emission of the LED array from each of the exposure devices 141 to 144 is applied to the curved photosensitive surface of the belt-shaped image forming body 1 with the same optical path length. In this manner, the color image forming apparatus of the present embodiment can also easily perform the alignment of the latent images of the respective colors, and can prevent color misregistration.

【The invention's effect】

As described above, the present invention includes two rotating rollers,
A belt-shaped image forming member stretched between the rotating rollers, and a convex surface, and the belt-shaped image forming member is formed such that the inner surface of the belt-shaped image forming member moves while sliding against the convex surface. A color image forming apparatus having a guide member disposed on the inside, and arranging at least a plurality of sets of exposure means and developing means in opposition to a photosensitive surface of the belt-shaped image forming body which is in sliding contact with the guide member; The plurality of exposure units are arranged on a single base, and the plurality of exposure units are configured to expose the belt-shaped image forming body from the convex surface side of the guide member, and By exposing the scanning exposure light to the belt-shaped image forming body with the same exposure length, it is possible to provide a color image forming apparatus capable of preventing color misregistration.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the color image forming apparatus of the present invention, FIG. 2 is a side view showing a process cartridge of the present embodiment, FIG. 3 is a sectional view showing an exposure unit of the present embodiment, FIG. 4 is a sectional view showing a state in which an exposure unit is incorporated in a process cartridge, FIG. 5 is a sectional view showing a state in which an exposure unit is incorporated in the process cartridge of the second embodiment, and FIG. 6 is a third embodiment. FIG. 7 is a cross-sectional view showing a state in which the exposure unit is incorporated in the process cartridge of the example, FIG. 7 is a cross-sectional view showing the exposure unit of the fourth embodiment, and FIG.
FIG. 9 is a sectional view showing an exposure unit of the fifth embodiment, and FIG. 9 is a sectional view showing a state where the exposure unit of the fifth embodiment is incorporated in a process cartridge. DESCRIPTION OF SYMBOLS 1 ... Belt-shaped image forming body, 2,3 ... Rotating roller 5 ... Guide member, 6 ... Cleaning device 8,10,12,14 ... Developing device 30 ... Process cartridge 40 ... Base, 41 ~ 44 ... Exposure equipment

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-133473 (JP, A) JP-A-1-112265 (JP, A) JP-A-61-36763 (JP, A) 53866 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) G03G 13/01 G03G 15/01-15/01 117 B41J 2/44

Claims (1)

(57) [Claims] 1. A belt-shaped image forming body stretched between two rotating rollers, a belt-shaped image forming body, and a convex surface, and the belt-shaped image forming inner surface slides on the convex surface. A guide member disposed inside the belt-shaped image forming body so as to move while being moved, and at least an exposure unit and a developing unit facing a photosensitive surface of the belt-shaped image forming unit that is in sliding contact with the guide member. In the color image forming apparatus in which a plurality of sets are arranged, the plurality of exposing units are arranged on a single base, and the plurality of exposing units are arranged on the belt-shaped image forming body from the convex side of the guide member. A color image forming apparatus for exposing, wherein the exposure light scanned by the plurality of exposure means exposes the belt-shaped image forming body with the same exposure length.