JPH02181763A - Paper feeding device for copying machine - Google Patents

Abstract

PURPOSE:To shorten time required for copying in a non-superimposing transfer mode by making the feeding speed of a paper which is fed toward a transfer drum through a conveying path in the non-superimposing transfer mode faster than that in a superimposing transfer mode. CONSTITUTION:A paper feeding roller 3 and an intermediate roller 6 are simulta neously started to be driven and the driving of the roller 3 is stopped by a CPU when the leading edge of the paper is detected by an intermediate sensor SE1. Next, when the leading edge of the paper is detected by a registration sensor SE2, the driving of the roller 6 is stopped after a sagging addition time T1 of T2 from the detection time of the sensor SE2 by the CPU. Then, the time T1 is set to the superimposing transfer mode and the time T2 is set to the non-superimposing transfer mode. Besides, the T1 is made longer than T2. Therefore, the paper feeding speed in the non-superimposing transfer mode becomes faster than that in the superimposing transfer mode and the time required for the copying in the non-superposing transfer mode is shortened.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a paper feeding device for a copying machine, and more particularly to a copying machine that can freely select between overlapping transfer and non-overlapping transfer modes. The present invention relates to a paper feeding device.

[Conventional technology]

It has a photoreceptor drum and a transfer drum disposed close to the photoreceptor drum, and the paper conveyed from the paper feed section through the conveyance path is wound around the transfer drum to transfer the toner image on the photoreceptor drum. A paper feeding device for a copying machine that transfers toner images and obtains copies, and can select between overlapping transfer and non-overlapping transfer modes.In the non-overlapping transfer mode, toner images are overlappingly transferred multiple times onto the paper on the transfer drum. Later, in the non-overlapping transfer mode, after the toner image has been transferred once, the sheet after the toner image has been transferred is removed from the transfer drum and the first sheet is fed into the transfer drum. There is a device.

Here, the overlap transfer mode is typically 1:! .

This mode is used for full-color copying, and in this mode, toner images of three different primary colors are superimposed and transferred onto the same transfer paper to obtain a full-color copy. In addition, modes for obtaining color copies by overlapping toner images of multiple colors even if they are not full color, and modes for overlapping transfer of the same toner images of the same color as a means of adjusting copy density are also discussed here. This is called the overlap transfer mode.

Further, the non-overlapping transfer mode is a mode typically performed during black-and-white copying, and is a mode in which a black toner image is transferred once. Basically, the mode is such that the transfer is completed in one time regardless of the color of the toner.

In a copying machine that can freely select between an overlap transfer mode and a non-overlap transfer mode, the process speed in both modes is set to be the same.

That is, during copying, the transfer paper is sent out from the paper feed section, stops at the registration roller section, and waits, and is rotated in synchronization with the position of the toner image on the photoreceptor drum. The sheet is fed out from the registration roller in synchronization with the arrival of the sheet gripper on the transfer drum, and this timing is also common in each mode.

Therefore, if the paper reaches the registration roller a predetermined time (feeding time from the registration roller to the above-mentioned meeting point) before the sheet gripper meets the paper exit section downstream of the registration storage controller. Often, this paper feeding speed is also common to each mode.

In the case of the overlap transfer mode, it is sufficient to feed the paper once for every rotation of the transfer drum for the number of overlap transfers.

Since magenta and yellow are transferred three times, the paper feed speed that can be fed within the time required for three rotations of the transfer drum is determined, and this paper feed speed also applies to the paper feed speed in non-overlap transfer mode. It is applied as is.

[Problem to be solved by the invention]

Since the paper feeding speed under the non-overlapping transfer mode is controlled by the paper feeding speed under the overlapping transfer mode, this is an obstacle to the request to shorten the copying time under the non-overlapping transfer mode.

An object of the present invention is to reduce copying time in non-overlap transfer mode.

[Means to solve the problem]

In order to achieve the above object, in the paper feeding device of the present invention, the feeding speed of the paper that is sent toward the transfer drum via the transport path in the non-overlap transfer mode is adjusted.

The feed speed is faster than that in the overlap transfer mode.

In addition, there is a registration storage control roller in the middle of the m-feeding path that temporarily stops the advance of paper sent out from the paper feed section and resumes feeding at a predetermined time, and a paper detection controller is provided near the upstream of this registration roller. It has a registration sensor.

The feeding of the feeding means is stopped after a required slack time after the paper detection signal is issued by the registration sensor, and the slack time in non-overlap transfer mode copying is made smaller than the slack time in overlap transfer mode. This is effective.

[For production] Faster than paper feed speed in overlap transfer mode.

In addition, the paper feeding speed is set at the maximum speed that meets the conditions under the non-overlap transfer mode.

〔Example〕

In FIG. 1, reference numeral 1 indicates a paper feed cassette constituting a paper feed section, and sheets S for transfer are stacked on a P8 moving plate 2. As shown in FIG. The uppermost sheet is pressed against the sheet feed roller 3 with appropriate pressure by an elastic means (not shown), and is fed out by rotation of the roller. Then, the ejected paper is separated into one sheet by a separation roller 4 which is driven in conjunction with the paper feed roller 3, and then sent to a registration roller rough through a guide 5 and an intermediate roller 6 that constitute a conveyance path. , here - once the standby state is reached. Then, the sheet is fed out from the registration storage roller 7 in synchronization with the arrival of the sheet gripper 9 on the transfer drum 8 . The leading edge of the paper is gripped by a sheet gripper 9 and wound around the transfer drum 8 one after another. Here, a paper feed roller 3, a separation roller 4,
The intermediate roller 6 and the like are used as paper feeding means.

On the other hand, a photoreceptor drum 10 is disposed close to and opposite to the transfer drum 8, and a transfer section 11 is constituted by this close opposing portion.

When the leading edge of the paper on the transfer drum 8 reaches the transfer unit 11, the leading edge of the toner image on the photosensitive drum also reaches the transfer unit 11.
When the two meet at the transfer unit 11, the transfer process is started and executed.

If the paper feeding speed from the N paper roller 3 to the registration roller rough is v3 in full color mode (three times overlapping transfer), the speed is increased to three times v3 in black and white mode. Even if the speed is increased in this manner, there is no change in the relationship that one frontispiece is printed per one rotation of the transfer drum 8, and no problem arises in terms of timing.

This will be explained more specifically.

The registration roller 7 has a function to correct the skew feeding of the paper, and even after the leading edge of the paper abuts against this registration roller rough, the intermediate roller G is driven for a short period of time to keep the paper from being skewed. A slack is formed, and using the elasticity of the paper due to this slack, the leading edge of the paper is brought into contact with the registration roller 7, and the paper is aligned.

Since the amount of slack must always remain unchanged, when changing the paper feeding speed in response to switching of the copy mode, control is required to keep the amount of slack constant according to the paper feeding speed.

The control will be explained.

In FIG. 1, an intermediate sensor SEI and a registration sensor S for detecting the leading edge of the paper are located near the intermediate roller 6 and upstream near the registration roller rough.
E2 are arranged respectively.

Paper detection information from these sensors is sent to the CPU (Central Processing Unit) that controls the processes of the copying machine, as shown in Figure 2.
It is designed to be input to the i-12.

In addition, mode switching information from each mode switching switch 13 for non-overlap transfer and 7-overlap transfer provided on the operation panel of the copying machine is also input to the CPU 12, and paper feed is performed according to this mode switching information. The speeds are switched as described above.

Furthermore, the CPU 12 turns on and off the drive of the paper feed roller 3.
Paper feed roller drive unit 14 and intermediate roller 6 to be turned off
A control signal is output to an intermediate roller drive unit 15 that controls on/off the drive of the intermediate roller.

The control timing between these sensors and rollers will be explained by referring to FIG. 1, FIG. 2, and FIG. 4 together with FIG.

When feeding paper, the paper feed roller 3 and intermediate roller 6 start driving at the same time.

Then, when the intermediate sensor SE1 detects the leading edge of the paper,
The drive of the paper feed roller 3 is stopped by a control signal from the CPU 12 that receives this information, and if the length of the paper is long, it is rotated along with the feeding of the paper.

This is because the feeding by the intermediate roller 6 continues. Eventually, when the leading edge of the paper is detected by the registration sensor SE2, a control signal from the CPU 12 that receives this information causes the intermediate roller 6 to be driven from the time of detection by the registration sensor SE2 to the slack time T1 or the time required to impart the slack. It stops after T2 elapses.

The above slack time Tt, Tt is the mode selector switch 1.
3, it is controlled with different values depending on the mode specified in advance.

If the slack time T1 is set to the value set in the overlap transfer mode, and the slack time T2 is set to the setting value in the non-overlap transfer mode, the paper feed speed in the former mode is faster than the paper feed speed in the latter mode, so T s > T. t, and an appropriate slack can be formed in accordance with the difference in paper feeding speed in each mode.

Note that in a configuration where the conveyance path is short and the intermediate roller 6 is not provided, the paper feed roller 3 is controlled.

〔Effect of the invention〕

According to the present invention, since the paper feeding speed in the non-overlap transfer mode is increased, the copying time in the same mode can be shortened by that much compared to the prior art.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a paper feeding device according to the present invention, FIG. 2 is a control block diagram, FIG. 3 is a timing chart thereof, and FIG. 4 is a flowchart thereof. 1...Paper feed cassette, 7...Registration storage reed roller, 8...Transfer drum, SF3...Registration sensor,...Sag time.

Claims (1)

[Claims] 1. A photoreceptor drum and a transfer drum disposed close to the photoreceptor drum, and a sheet conveyed from a paper feed section through a conveyance path is wound around the transfer drum and then wrapped around the transfer drum. A paper feeding device of a copying machine that transfers the toner image on the photosensitive drum to obtain a copy, and can select between overlapping transfer and non-overlap transfer modes, and in the case of non-overlap transfer mode, the paper on the transfer drum After the toner images are transferred multiple times, or in the non-overlap transfer mode, after the toner image is transferred once, the paper after the toner image is transferred is removed from the transfer drum and sent out, and the next sheet is sent to the transfer drum. In the paper feeding device of a copying machine that uses a non-overlap transfer mode, the speed at which the paper is fed toward the transfer drum via the conveyance path in the non-overlap transfer mode is set to be faster than the same paper feed speed in the overlapping transfer mode. A paper feed device for a copying machine characterized by: 2. There is a registration roller in the middle of the conveyance path that temporarily stops the advance of the paper sent out from the paper feed unit and restarts it at a predetermined time, and a registration roller for paper detection is installed near the upstream of this registration roller. The feeding means has a registration sensor that stops feeding after a required slack time after the paper detection signal is issued by the registration sensor, and the above-mentioned slack time during non-overlap transfer mode copying is used for overlapping transfer mode. 2. The paper feed device for a copying machine according to claim 1, wherein the paper feed device is made smaller than the sag time.