JP3632373B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as an electrophotographic copying apparatus or a laser printer, and more particularly to an image forming apparatus provided with a transfer device configured to transfer a toner image in a direction orthogonal to a conveyance direction of printing paper.
[0002]
[Prior art]
In the field of electrophotographic image forming apparatuses, for example, a toner type that is excellent in resolution and can form a clear image, as represented by a laser printer, is widely used. As one of such toner type image forming apparatuses, the applicants of the present application, in Japanese Patent Application No. 7-328600, transfer a toner image while moving the toner image carrier in a direction perpendicular to the printing paper conveyance direction. An orthogonal transfer type image forming apparatus was proposed.
[0003]
3 and 4 show an image forming apparatus according to the previous application. FIG. 3 is a schematic diagram of a main part of a conventional orthogonal transfer type image forming apparatus. FIG. 4 is a perspective view of a main part of the image forming apparatus of FIG. It is.
[0004]
3 and 4, the photosensitive belt 1 is wound around support rollers 2a and 2b that are rotationally driven by a motor (not shown) so as to be able to travel in the direction of arrow A shown in FIG. The photosensitive belt 1 is coated on the surface with an organic photoconductive material, and the traveling direction thereof is orthogonal to the paper feeding direction of the paper 6 supplied onto the transfer plate 8 by the paper transport roller 9. Then, around the photosensitive belt 1, a charger 3 for uniformly charging the photosensitive belt 1, and an exposure unit 5 for irradiating a laser beam 5a to form an electrostatic latent image on the surface of the photosensitive belt 1. A developing roller 4a for supplying toner and a developing device 4 for visualizing the electrostatic latent image as a toner image are sequentially arranged.
[0005]
Further, a transfer counter roller 7 whose axis is orthogonal to the running direction of the photosensitive belt 1 is disposed in a position in the loop of the photosensitive belt 1 and facing the transfer plate 8. The transfer counter roller 7 is connected to a motor (not shown) to apply a certain tension to the photosensitive belt 1 and at the same time, feeds the sheet 6 while rotating on the inner surface of the loop of the photosensitive belt 1. It is possible to travel in a direction orthogonal to the direction.
[0006]
In such a conventional image forming apparatus, the image forming operation of the toner image on the photosensitive belt 1 onto the paper 6 is as follows.
[0007]
When an image forming operation is instructed by the control unit of the image forming apparatus, the support rollers 2a and 2b are rotated by driving the motor, and the photosensitive belt 1 starts to travel in the direction of arrow A in FIG. The surface of the photosensitive belt 1 is first charged by the charger 3 in accordance with the content of the image to be formed, and subsequently the charged potential is lowered by the laser beam 5a emitted from the exposure device 5. As a result, an electrostatic latent image is formed.
[0008]
When the portion of the photoreceptor belt 1 where the electrostatic latent image is formed reaches the developing device 4, the developing roller 4 a of the developing device 4 is rotated by its driving means (not shown) and abuts against the photoreceptor 1. As a result, the electrostatic latent image is developed by the toner adhering to the surface of the developing roller 4a while the photosensitive belt 1 is nipped and moved between the developing roller 4a and the supporting roller 2a, and the photosensitive belt 1 is developed on the photosensitive belt 1. A toner image is formed.
[0009]
When a toner image corresponding to one sheet 6 is formed on the surface of the photoreceptor belt 1 by the above operation, the transfer counter roller 7 rotates in the direction of the arrow shown in FIG. 6 along the line. During the parallel movement of the transfer counter roller 7, the photosensitive belt 1 is sequentially pressed against the paper 6 by the transfer counter roller 7, and the toner image on the photosensitive belt 1 is transferred onto the paper 6.
[0010]
After this transfer, the sheet conveying roller 9 is rotated by a motor (not shown), and the sheet 6 is moved on the transfer plate 8 in a direction orthogonal to the traveling direction of the photosensitive belt 1 as shown in FIG. It is transported to the position.
[0011]
As described above, a predetermined image such as a character or a figure is formed on one sheet of paper 6, and similar image forming operations are sequentially repeated as necessary. It is to be noted that a static eliminator for static elimination after transfer and a cleaning device for removing afterimage toner are provided around the photosensitive belt 1 in an image forming apparatus including a belt that runs as a conventional image carrier. Same as the case.
[0012]
[Problems to be solved by the invention]
In a system in which a toner image is formed on the photosensitive belt 1 and transferred to the paper 6, it is only necessary to perform charge removal, afterimage cleaning, and subsequent charging, exposure, and development processes in order after one transfer. Thereafter, the toner image on the photosensitive belt 1 is transferred to the paper 6. Therefore, in order to perform these operations, a layout in which the charger 3, the exposure device 5 and the developing device 4 are arranged in order around the photosensitive belt 1 as shown in the example shown in FIG. What is necessary is just to make it the design which can ensure the space which can be laid out in an apparatus.
[0013]
However, in the conventional structure, the charger 3 and the exposure device 5 are arranged in the vicinity of the support roller 2 b that is one end of the loop of the photoreceptor belt 1 so that an electrostatic latent image is formed on the photoreceptor belt 1. The developing device 4 is arranged near the support roller 2a at the other end so as to obtain a toner image. In other words, the layout is such that the electrostatic belt latent image and the toner image forming front are respectively provided at both ends of the loop of the photosensitive belt 1, and the functional parts are divided into two portions. Such a layout has a design constraint that if the developing device 4 and the exposure device 5 are arranged close to each other, the exposure device 5 is contaminated by the toner of the developing device 4, and this must be avoided. Because it receives.
[0014]
If the combination of the charger 3 and the exposure unit 5 is separated from the developing unit 4 in this way, the layout is such that these devices protrude outward as viewed in the width direction of the transfer plate 8 as shown in FIG.
[0015]
Further, since the photosensitive belt 1 needs to be deformed in such a direction that the upper surface of the paper 6 is pressed by the transfer counter roller 7, the support roller 2b at one end of the loop is positioned close to the transfer plate 8 and the support roller 2b at the other end. The path of the photosensitive belt 1 must be inclined obliquely by separating the upper side. Therefore, the charger 3 and the exposure device 5 provided in the vicinity of the support roller 2 b increase in the height in the height direction with respect to the transfer plate 8.
[0016]
As described above, in the conventional image forming apparatus, since the layout of the charger 3, the exposure unit 5 and the developing unit 4 with respect to the loop of the photosensitive belt 1 is not appropriate, the image forming apparatus has a direction in which the paper 6 is orthogonal to the passing direction. Both the bulk and the bulk in the height direction are increased. Therefore, the space ratio of the image forming apparatus occupying in the copying machine or printer also increases, and there remains an obstacle in the design of downsizing of the entire apparatus.
[0017]
The problem to be solved in the present invention is to further reduce the size of the image forming apparatus by optimizing the arrangement of the devices for charging, exposing and developing around the photosensitive belt.
[0018]
[Means for Solving the Problems]
The present invention places the photoreceptor belt loop provided as toner image carrier, so as to have loops and inclined obliquely upward a feed direction and can travel direction or in the same direction perpendicular to the recording medium, the A transfer counter roller that rotates on the inner surface of the loop of the photosensitive belt and moves along the recording medium is provided, and the toner image carried on the photosensitive belt is transferred onto the recording medium.
An image forming apparatus having a transfer device for transferring by continuous pressing by a roller, wherein a developing device is arranged facing the lower end side of the inclined loop of the photosensitive belt, and the loop of the developing device and the photosensitive belt is The electrostatic latent image forming means is arranged so as to completely overlap within the area of the planar field of view.
[0019]
With this configuration, the electrostatic latent image forming means can be included in the plane occupied by the developing device and the photosensitive belt, so that the entire apparatus can be saved in space and the apparatus can be miniaturized. Become.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
According to the first aspect of the present invention, the closed-loop photosensitive belt provided as the toner image carrier can run in a direction perpendicular to or in the same direction as the recording medium feeding direction and has a loop inclined obliquely upward. And a transfer counter roller that rotates on the inner surface of the loop of the photosensitive belt and moves along the recording medium, and continuously carries the toner image carried by the transfer counter roller onto the recording medium of the photosensitive belt. An image forming apparatus provided with a transfer device that transfers by a simple press, wherein a developing device is arranged facing the lower end side of the inclined loop of the photosensitive belt, and the area of the planar field of view of the loop of the developing device and the photosensitive belt The electrostatic latent image forming means is disposed so as to be completely overlapped with the electrostatic latent image, and the electrostatic latent image forming means is included in a plane occupied by the developing device and the photosensitive belt.
[0021]
According to the second aspect of the present invention, the loop length of the photosensitive belt is set to a length that cuts through the entire length of the recording medium onto which the toner image is transferred. Even if the photosensitive belt is inclined, the entire recording medium is provided. On the other hand, it has the effect of being able to transfer.
[0022]
According to a third aspect of the present invention, the electrostatic latent image forming means includes a charger and an exposure device arranged in order from the upper end to the lower end of the inclined loop in the middle of a path in which the photosensitive belt faces the side opposite to the recording medium. And has an action of obtaining an electrostatic latent image by exposing after exposure of the photosensitive belt.
[0023]
According to a fourth aspect of the present invention, the charger is arranged so as to be biased toward the lower end side of the inclined loop of the photosensitive belt, and the exposure device covers the charger, and the upper end of the exposed device is the inclined loop of the photosensitive belt. The arrangement is included below the upper end, and has the effect that each of the exposure device and the charging device has a layout that does not protrude beyond the vertical bulk of the photosensitive belt.
[0024]
According to a fifth aspect of the present invention, the developing device is disposed in such a relationship that a developing roller provided in the developing device and contacting the surface of the photosensitive belt so as to adhere toner is buried below the lower end of the inclined loop of the photosensitive belt. The charging device and the exposure device can be arranged lower than the upper end of the loop of the photosensitive belt.
[0025]
Hereinafter, specific examples of embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a schematic diagram of a main part of an image forming apparatus according to a first embodiment of the present invention.
[0026]
In addition, about the same member about the member of the apparatus in FIG.3 and FIG.4 mentioned as a prior art example, it instruct | indicates with a common code | symbol, The detailed description is abbreviate | omitted.
[0027]
3 and 4, the arrangement positions of the support rollers 2 a and 2 b of the photosensitive belt 1 with respect to the transfer plate 8 are the same as those in the conventional example, and the loop in the circumferential direction of the photosensitive belt 1 is relative to the transfer plate 8. The posture is going up to the right. That is, the positional relationship is such that the direction in which the photosensitive belt 1 that has gone through the developing process by the developing device 4 disposed in the vicinity of the support roller 2a passes through the sheet 6 on the transfer plate 8 is inclined upward.
[0028]
The arrangement of the developing device 4 with respect to the support roller 2a is the same as that of the conventional example, and the difference is that the charger 3 faces a path on the upper side of the photosensitive belt 1 and is biased toward the support roller 2a on one end side. The exposure unit 5 is arranged to cover a part of the developing unit 4 and the charging unit 3.
[0029]
That is, since an electrostatic latent image may be formed on the photosensitive belt 1 before reaching the developing device 4, the path on the opposite side of the transfer surface of the photosensitive belt 1 (upper travel line in the figure). If the charger 3 is disposed between the two, the photosensitive belt 1 can be charged. An electrostatic latent image can be formed by irradiating the photosensitive belt 1 with the laser beam 5a after this charging, so that the laser beam 5a strikes the photosensitive belt 1 between the charger 3 and the developing device 4. The exposure unit 5 may be arranged. Further, since it is preferable to perform the exposure without lowering the charging potential of the photosensitive belt 1, the distance between the charged portion by the charger 3 and the irradiation region of the laser beam 5a is made as short as possible.
[0030]
As one that satisfies the above conditions, the layout of each device shown in FIG. 1 is one optimal example. In this layout, both the charger 3 and the exposure device 5 are included in the plan view of the loop length of the photosensitive belt 1 as compared with the conventional example, and the bulk in the direction of cutting through the paper 6 is increased. Get smaller. In addition, since the upper end portion of the exposure device 5 can be stored lower than the support roller 2b portion of the inclined loop of the photosensitive belt 1, the vertical dimension can also be reduced. Furthermore, since the exposure device 5 can be provided above the developing device 4, the exposure device 5 is prevented from being contaminated by the toner of the developing device 4.
[0031]
(Embodiment 2)
FIG. 2 is a schematic diagram of a main part of the image forming apparatus according to the second embodiment of the present invention. The same members as those shown in FIG.
[0032]
In this example, as compared with the configuration of FIG. 1, the relative height of the developing device 4 with respect to the transfer plate 8 is reduced as a positional relationship such that the developing roller 4a of the developing device 4 sinks obliquely to the lower left of the support roller 2a. It is different. Another difference is that the charger 3 is placed closer to the support roller 2a and positioned lower, and the height of the exposure device 5 is also lowered by an amount corresponding to the downward shift of the charger 4.
[0033]
In this example, the volume in the direction of cutting through the paper 6 is about the same as that in the example of FIG. 1, but the volume in the vertical direction can be further reduced, and the size can be further reduced.
[0034]
As can be seen from the first and second embodiments described above, the standard of the size required for the transfer device is the plane area occupied by the width of the transfer plate 8 and the plane area of the inclined photoreceptor belt 1. This is the bulk of the loop of the photoreceptor belt 1 in the vertical direction. In the present invention, each of the charger 3 and the exposure unit 5 is overlapped on the developing unit 4 positioned on one end side of the loop and on the lower end side of the slope. The size and the bulk in the vertical direction can be kept small.
[0035]
【The invention's effect】
In the first aspect of the present invention, since the electrostatic latent image forming means can be included in the plane occupied by the developing device and the photosensitive belt, the plane area occupied by the transfer device can be reduced, The transfer device itself and the entire image forming apparatus incorporating the same can be miniaturized.
[0036]
According to the second aspect of the invention, since the transfer can be performed on the entire recording medium even when the photosensitive belt is inclined, the transfer can be performed regardless of the size of the recording medium.
[0037]
According to the third aspect of the present invention, an electrostatic latent image can be obtained by exposure after charging of the photosensitive belt. Therefore, even if the image forming means is installed near the developing device, the toner image can be formed with a normal transfer device. The design can be performed in the same manner and does not require a special member or circuit configuration.
[0038]
According to the fourth aspect of the present invention, a layout is obtained in which each of the exposure device and the charger does not protrude beyond the bulk of the photosensitive belt in the vertical direction, so that the image forming apparatus can be further downsized.
[0039]
According to the fifth aspect of the present invention, since the charger and the exposure device can be arranged lower than the upper end of the loop of the photosensitive belt, the image forming apparatus can be further miniaturized.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a main part of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a schematic diagram of a main part of an image forming apparatus according to a second embodiment of the present invention. FIG. 4 is a schematic view of a main part of an image forming apparatus using an orthogonal transfer method.
DESCRIPTION OF SYMBOLS 1 Photoconductor belt 2a-2b Support roller 3 Charger 4 Developing device 4a Developing roller 5 Exposure device 5a Laser beam 6 Paper 7 Transfer counter roller 8 Transfer plate 9 Paper conveyance roller

Claims (5)

A closed-loop photosensitive belt provided as a toner image carrier is disposed so as to be able to run in a direction orthogonal to or the same direction as the recording medium feeding direction and to have a loop inclined obliquely upward . A transfer counter roller that rotates on the inner surface of the loop and moves along the recording medium, and a transfer device that transfers the carried toner image onto the recording medium of the photosensitive belt by continuous pressing by the transfer counter roller. In this image forming apparatus, a developing device is arranged facing the lower end side of the inclined loop of the photosensitive belt, and the developing device and the photosensitive belt loop are electrostatically electrostatically overlapped with each other within the area of the planar field of view. An image forming apparatus comprising a latent image forming means. 2. The image forming apparatus according to claim 1, wherein the loop length of the photosensitive belt is set to a length that cuts through the entire length of the recording medium onto which the toner image is transferred. The electrostatic latent image forming means is a charger and an exposure device arranged in order from the upper end to the lower end of the inclined loop in the middle of a path in which the photosensitive belt faces the side opposite to the recording medium. The image forming apparatus according to claim 1 or 2. The charger is arranged so as to be biased toward the lower end side of the inclined loop of the photosensitive belt, and the exposure device covers the charger, and the upper end of the exposing device is included below the upper end of the inclined loop of the photosensitive belt. The image forming apparatus according to claim 3, wherein the image forming apparatus is arranged. The developing device is arranged in such a relationship that a developing roller provided in the developing device and contacting the surface of the photosensitive belt to adhere toner is buried below the lower end of the inclined loop of the photosensitive belt. Item 5. The image forming apparatus according to Item 4.

Images