JPH0535022A - Paper suction device for image forming device - Google Patents

Abstract

PURPOSE:To suck and support even a paper having a complicated shape regardless of the size and the shape of the paper by providing spherical bodies inside plural suction holes and constructing the suction hole so that its aperture may be smaller than the diameter of the spherical body on the paper suction surface of a paper supporting body and a surface on a chamber side. CONSTITUTION:The plastic spherical body 25 is disposed inside the suction hole 23 of a drum 20. The diameter of the spherical body 25 is larger than the small diameter part of the suction holes 23a and 23b, and smaller than the diameter of a large diameter part and an escape hole 23c, so that the spherical body 25 can move inside the suction hole 23 but does not drop. The spherical body 25 is sucked to the inner peripheral side of the suction hole 23b and tightly closes the suction hole 23 at the suction hole 23 whose suction surface is not blocked by a photosensitive paper 10. At the suction hole 23 whose suction surface is blocked by the photosensitive paper 10, the photosensitive paper 10 is sucked and tightly closes the suction hole 23. When the photosensitive paper 10 wraps around the first half part of the suction hole 23 with the rotation of the drum 20, the chamber 27b is made in a negative pressure state and the first half part of the photosensitive paper 10 is sucked.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet suction device of an image forming apparatus, and more particularly, to an image forming apparatus which sucks and supports an image forming sheet by a negative pressure on a cylindrical or flat sheet support. The present invention relates to a paper suction device of an apparatus.

[0002]

2. Description of the Related Art Conventionally, in a paper suction device of an image forming apparatus, a negative pressure is applied to the inside of a suction hole formed at an appropriate position of a paper support to form an image on a photosensitive paper or a transfer paper. The paper was supported by suction. When using image forming papers of several sizes, it was necessary to switch the suction position according to the paper size.

For example, as shown in FIG. 6, a drum 50, which is a paper support, is provided with a plurality of suction holes 53a, 53b having a diameter of about 1 mm and not shown 53c, and is shown in FIG. As described above, the chamber 54 is provided inside the drum 50 corresponding to the suction holes 53a, 53b and 53c.
a, 54b and 54c are attached. Suction hole 5
3a and 53b correspond to the front end portion and the rear end portion of the A4 size photosensitive paper, respectively. For the A3 size photosensitive paper, the suction hole 53a is common to the A4 size and the suction hole 53c is the rear end. It corresponds to the department. Chambers 54a, 5
4b and 54c are connected to a suction pump 60 via hoses 55a, 55b, 55c, valves 57a, 57b, 57c and a hose 58.

When the A4 size photosensitive paper 70 is supplied to the drum 50, the valve 57 is first rotated as the drum 50 rotates.
a is driven, and a negative pressure is generated in the chamber 54a by the suction pump 60 that has been driven in advance.
The front end of the drum is sucked onto the surface of the drum 50 by the suction hole 53a. Next, when the drum 50 is wound up to the rear end of the photosensitive paper 70, the valve 57b is driven and the chamber 54
Negative pressure is also generated in the inside of b, and the rear end portion of the photosensitive paper 70 is also attracted to the suction hole 53b.

In the case of A3 size photosensitive paper, similarly, the front end is sucked by the suction hole 53a and the rear end is sucked by the suction hole 53c.

[0006]

However, since the conventional paper suction device has the above-mentioned structure, there is a problem that it cannot pick up paper other than the preset size. Further, the shape that can be adsorbed was also limited to a rectangle.

The present invention has been made in order to solve the above-mentioned problems, and regardless of the size and shape of the paper,
It is an object of the present invention to provide a sheet suction device of an image forming apparatus capable of sucking and supporting a sheet having a complicated shape.

[0008]

In order to achieve this object, a paper suction device of the present invention has a sphere inside a suction hole, and the suction hole is formed on the paper suction surface of the paper support and the surface on the chamber side. The diameter is smaller than the diameter of the sphere.

[0009]

In the sheet suction device of the present invention having the above structure, the sphere provided inside the suction hole is movably held in the suction hole. When an image forming sheet such as a photosensitive sheet or a transfer sheet is conveyed to a predetermined position and the inside of the chamber is made negative pressure by the negative pressure generating means, the sphere is sucked in the suction hole where the sheet does not block the suction surface. The suction hole to block the suction hole, and the sheet sucks the suction hole to block the suction surface.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

First, the structure of the sheet suction device of this embodiment will be described with reference to FIG. The drum 20, which is a paper support that attracts and conveys the photosensitive paper 10, is composed of an outer drum 20a around which the photosensitive paper 10 is wound, and an inner drum 20b fitted inside the outer drum 20a.

In the outer drum 20a, suction holes 23a having a larger diameter on the inner peripheral side than on the outer peripheral side are formed at predetermined intervals, and on the inner drum 20b, a suction hole 23b larger in diameter on the outer peripheral side than the inner peripheral side. Is opened at a position corresponding to the suction hole 23a. Further, the suction hole 23b is provided with a clearance hole 23c rearward with respect to the rotation direction of the drum 20, and the suction hole 23a, the suction hole 23b and the clearance hole 23c.
To form the suction hole 23. Inside the suction hole 23,
A sphere 25 made of plastic is arranged. Since the diameter of the sphere 25 is set to be larger than the small diameter portions of the suction holes 23a and the suction holes 23b and smaller than the large diameter portions thereof and the diameters of the escape holes 23c, they can be moved inside the suction holes 23. , It does not fall from the suction hole 23.

All the suction holes 23 are provided on the inner circumference of the drum 20.
A chamber 27 is attached so as to cover the sheet. The chamber 27 is composed of a portion 27a that covers a row of suction holes corresponding to the front end portion of the sheet, and a first half portion 27b and a second half portion 27c that divide the other portion into two parts. There is. The chamber 27 is connected to a vacuum pump (not shown) which is a negative pressure generating means through a valve (not shown).

Next, the operation of this embodiment will be described with reference to FIGS. 2 is a cross-sectional view of the AA cross section of FIG. 1 viewed in the direction of the arrow. When the photosensitive paper 10 is conveyed to a predetermined position along the outer circumference of the drum 20 by the conveying roller 30a and the portion of the drum 20 corresponding to the front end portion of the paper is rotated to that position, the front end portion of the photosensitive paper is moved by the photosensitive paper pressing roller 30b. The chamber 27a is pressed against the drum 20, and a negative pressure is selectively applied to the chamber 27a by a vacuum pump and a valve (not shown) so that the chamber 27a is adsorbed.

At this time, as shown in FIG. 2, in the suction hole in which the photosensitive paper 10 does not close the suction surface, the sphere 25 becomes the suction hole 23.
Adsorbed on the inner peripheral side of b to seal the suction hole. In addition, the photosensitive paper 10 is adsorbed in the suction hole where the photosensitive paper 10 closes the suction surface, and the suction hole is sealed. The photosensitive paper 10 is wound around the front half of the suction hole 23 as the drum 20 rotates.
In this state, the chamber 27b is also made to have a negative pressure, and the first half of the photosensitive paper 10 is adsorbed. After that, when the suction holes in the last row reach the position of the photosensitive paper pressing roller 30b, the chamber 27c is also made negative pressure, and the adsorption of the photosensitive paper 10 is completed.

The drum 10 further rotates, and as shown in FIG.
When the suction hole 23 reaches the upper part of the drum, the sphere 25 is movable inside the suction hole sucking the photosensitive paper 10, and thus falls in the inner circumferential direction of the drum 20. However, since the suction hole 23 is provided with the escape hole 23c, the spherical body 25 does not fall into the escape hole 23c and close the suction hole 23b as shown in FIG.

In this way, for example, a circular sheet as shown in FIG. 4 or a sheet having a complicated shape as shown in FIG. 5 can be sucked and supported. Therefore, it is also possible to adsorb the photosensitive paper, which has been cut out according to the desired image, and form an image on it. Further, the size of the photosensitive paper is not limited as long as it is within the range in which the photosensitive paper can be wound on the drum, and therefore, a paper having a size that is not wasted according to a desired image can be used.

The present invention is not limited to the embodiments described in detail above, and various modifications can be made without departing from the spirit of the invention. For example, although the cylindrical paper support is described in detail in the present embodiment, the shape of the paper support is not limited to the cylindrical shape, and may be, for example, a flat shape. In this case, in an apparatus in which the suction side of the paper is always facing down during the image forming process,
The above-mentioned escape hole 23c is unnecessary, and a simpler structure can be obtained. Further, the sphere 25 does not have to be made of plastic, but can be made of steel, rubber or the like.

[0019]

As is apparent from the above description, since the paper suction device of the present invention can suction and support the paper regardless of the shape, size, etc. of the paper, it can handle various sizes of paper. However, it is also possible to use paper of complicated shape.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a sheet suction device that is an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a cross-sectional view of the sheet suction device in a state in which the drum rotates from FIG. 1 and a sheet is on the drum.

FIG. 4 is a diagram showing an example of a paper shape that can be adsorbed.

FIG. 5 is a diagram showing another example of the shape of a sheet that can be adsorbed.

FIG. 6 is a perspective view showing a configuration of a conventional paper suction device.

FIG. 7 is a partial cross-sectional view showing the structure of a conventional paper suction device.

[Explanation of symbols]

20 drums (paper support) 23 Suction hole 23c escape hole 25 spheres 27 chambers

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takeshi Asano             Brother work, 15-1 Naeshiro-cho, Mizuho-ku, Nagoya-shi             Business

Claims (2)

[Claims] 1. A paper support having a plurality of suction holes, a chamber provided on a surface of the paper support opposite to a paper suction surface to cover the suction holes, and a negative pressure for generating a negative pressure inside the chamber. A sheet suction device of an image forming apparatus, which has a generating means and performs suction support of a sheet by making a negative pressure inside the suction hole, has a sphere inside the suction hole, and the suction hole is a sheet support. The sheet suction device of the image forming apparatus is characterized in that the diameters of the sheet suction surface and the chamber side surface are smaller than the diameter of the sphere. 2. The sheet suction device of the image forming apparatus according to claim 1, wherein the suction hole is formed with an escape hole for preventing the sphere from falling to the chamber side.