JPH03293253A - Paper suction type conveyor - Google Patents

Abstract

PURPOSE:To reduce an air leakage out of a suction hole uncovered with paper as well as to secure the extent of stable suction force by installing an on-off means which varies an opening state of the suction hole according to size detection contents of the paper being conveyed. CONSTITUTION:Attracting the inside of a tank 6 having plural pieces of suction holes 7 adjoined to a paper conveying passage 5, a sheet of paper 3 is attracted onto this passage 5 and conveyed. At this time, there is provided a detecting means 10 for paper size to be conveyed. An opening state of each suction hole 7 is varied by an on-off means 11 according to detection contents of this detecting means 10. With this constitution, the number and areas of these suction holes 7 covered with the paper 3 are optimized according to the passing paper size.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a paper conveyance device used in image forming apparatuses such as copying machines, printers, and facsimiles, and particularly to a paper suction type conveyance device that can generate reliable paper suction force. Concerning what was done.

[Conventional technology]

Examples of conventional paper suction type conveyance devices include those shown in Figs. 5 and 6.
There is something like the one shown in the figure. In the figure, 1 is a photoreceptor, 2 is a transfer/separation charger, 3 is paper, and 4 is a transport device.The transport device 4 consists of a transport belt 5 and a suction tank 6. The holes 7 are open to the conveyance path surface. The paper 3, on which the image has been transferred by the transfer/separation charger 2 on the photoreceptor 1, is sent onto the conveyance device 4 from the leading end side. The inside of the suction tank 6 is suctioned by a suction device (not shown), and air outside the suction tank 6 is sucked through the suction hole 7 .

When the paper 3 is positioned above the suction hole 7 , the paper 3 is attracted onto the conveyance path surface by the above-mentioned suction air, and is conveyed to the fixing roller 8 by the conveyance belt 5 .

[Problem to be solved by the invention]

In the conventional paper suction conveyance device described above, the number, opening area, and opening position of the suction holes 7 are all fixed. Therefore, when using small-sized paper or when the leading edge and trailing edge of the paper pass through, the suction hole 7 is not covered by the paper.
Can be done. The suction holes 7 that are not covered by the paper naturally suck in outside air, and the suction force against the slicked paper is insufficient, resulting in paper not being fed or image defects due to vertical movement of the paper. Sometimes.

In order to ensure a stable suction force, conventional measures have been taken such as providing suction holes as close to the end of the conveying device as possible, but this has not been a sufficient measure.

The present invention has been made in view of the above-mentioned conventional problems, and is an attempt to solve the above-mentioned problems by optimizing the number and area of suction holes covered by paper according to the size of the paper passing through.

[Means to solve the problem]

In order to achieve the above-mentioned object, the present invention provides a paper suction type conveyance device that suctions the inside of a tank having a plurality of suction holes facing the paper conveyance path, and conveys the paper by suctioning it onto the surface of the conveyance path. The apparatus is configured to include a paper size detecting means, and an opening/closing means for changing the opening state of the suction hole in accordance with the detection contents of the detecting means.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

In addition, in the following, the same reference numerals are given to parts that are common to those of the conventional art, and redundant explanations will be omitted.

FIG. 1 and FIG. 2 are diagrams showing one embodiment of the present invention,
FIG. 1 is a cross-sectional side view corresponding to FIG. 5, and FIG. 2 is a plan view of the paper conveyance path seen from above in FIG. 1.

In the figure, reference numeral 10 denotes a sensor that detects the size of the paper 3 to be transported, specifically the length in the feeding direction, based on the contact time with the paper 3. In addition, numeral 11 in the figure is an opening/closing mechanism, and sensor 10
The numerical aperture of the suction hole 7 is changed according to the detected length of the paper 3 in the feeding direction.

As shown in FIG. 2, in this embodiment, the eight suction holes 7 are divided and controlled into four on the photoreceptor 1 side and four on the fixing roller 8 side. A pair of shield plates 12.13 are provided in the suction tank 6 for switching the opening state of the suction holes 7, and each shield plate 12.13 is slid by a solenoid 14.15, so that the suction holes 7 in charge can be opened and closed. It's Nishide.

Note that reference numerals 16 and 17 in the figure represent biasing springs.

Next, the operation of this embodiment will be explained with reference to FIGS. 3a, 3b, and 4c, and FIG. 4.

In the initial state, the sensor 10, both solenoids 12.
13 are all OFF.

Here, when the sensor 10 detects conveyance of the paper 3 and turns on, the solenoid 15 also turns on. When the solenoid 15 is turned on, the shield plate 13 is pulled downward in FIG. 2 against the biasing force of the spring 17, and closes the four suction holes 7 on the fixing roller 8 side. As a result, only the four suction holes 7 on the photoreceptor 1 side are opened, and the suction force from the suction holes 7 is concentrated on the leading edge side of the paper 3. Adsorb it to the transport road surface. As the conveyor belt 5 rotates, the sheets 3 are successively attracted to the conveyance path surface from the leading edge side and conveyed (FIG. 3a).

The solenoid 15 is turned off after a predetermined time t2, and accordingly, the shield plate 13 is turned off by the spring 17.
It is returned to the position shown in the figure, and all suction holes 7 are opened. The time t2 is set to approximately correspond to the time from when the sensor 10 is turned on until the leading edge of the paper 3 passes through the center of the tank 6 (indicated by a two-dot chain line in FIG. 3a). At this time, the paper 3 is attracted to the entire transport path surface (the third
Figure b).

When the trailing edge of the paper 3 passes the position of the sensor 10, the sensor 10 is turned off. That is, the time t1 is the time required for the paper 3 to pass the sensor 10, and this is detected as a substitute characteristic of the paper size.

Furthermore, after the sensor 10 is turned off, the solenoid 14 is turned on when three hours have elapsed. When the solenoid 14 is turned ON, the shield plate 12 is pulled downward in FIG. Open only the four suction holes 7 on the 8 side. As a result, the suction force from the suction hole 7 is concentrated on the fixing roller 8 side. Time 3 is the approximate time from when the sensor 10 is turned off until the trailing edge of the paper 3 reaches the center of the tank 6;
At this time, the leading edge of the paper 3 has already approached the fixing roller 8 (FIG. 3C), and the trailing end of the paper 3 is firmly attracted to the transport path surface by the rotation of the transport bells 1 to 5, and the paper 3 is transported.

The solenoid 14 turns OFF after time t4 has elapsed since it was turned ON.
It becomes F. This time t4 is the time required for the rear end of the paper 3 to completely pass through the tank 6 after passing through the center of the tank 6. As a result, each section returns to its initial state and waits for the arrival of the next sheet 3.

Note that instead of the sensor 10 of this embodiment, the operation of the opening/closing mechanism may be determined based on a signal from a paper feed cassette size display mechanism. Further, in this embodiment, the opening/closing state of the suction hole is switched depending on the length of the paper in the feeding direction, but it is also possible to switch the open/closed state by detecting the widthwise dimension of the paper.

〔Effect of the invention〕

As described above, the paper suction type conveyance device according to the present invention is equipped with an opening/closing means that changes the opening state of the suction hole according to the detected size of the paper to be conveyed, so that it is not covered with paper. This has the effect of reducing air leakage from the suction holes, ensuring stable suction force, and is particularly effective in image forming apparatuses that employ an upper paper conveyance system. This has the effect of reducing image disturbances caused by non-feeding at the leading and trailing ends of the paper, where the degree of air leakage increases, paper jams, and vertical movement of the paper before fixing.

[Brief explanation of drawings]

1 to 4 show a paper suction type conveyance device according to an embodiment of the present invention, and FIG. 1 is a cross-sectional side view corresponding to FIG.
Figure 2 is a plan view of the paper conveyance path seen from above in Figure 1;
Figures 3a, b, and c are cross-sectional side views showing the paper transport state and the opening/closing state of the suction holes. Figure 3a shows the initial state of paper transport, and Figure 3 shows the middle stage of paper transport. , FIG. 3C shows the final state of paper conveyance, FIG. 4 is a timing chart showing the relationship between paper detection and the opening/closing state of the suction hole, and FIG. 5 is a cross-sectional side view of a conventional paper suction type conveyance device. FIG. 6 is a perspective view of the same. 111. Photoreceptor 209. Transfer/separation charger 3
14. Paper 461. Conveying device 51.6 Conveying belt 62. , suction tank 761. Suction hole 8°9.
Fixing roller 10 , Sensor 11 , Opening/closing mechanism 12.13 , Shield plate 14.15 , Solenoid 16.17 , Spring

Claims (1)

[Claims] In a paper suction conveyance device that suctions the inside of a tank having a plurality of suction holes facing a paper conveyance path to suck and convey paper onto the surface of the conveyance path, a means for detecting the size of the sheet to be conveyed; A paper suction type conveyance device characterized by comprising an opening/closing means for changing the opening state of the suction hole according to the detected contents.