JPH0350107Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a paper feed control device, and particularly to a paper feed control device suitable for use in copying machines with increased process speeds. .

(Prior Art) A conventional paper feed control device for copy paper in a copying machine will be described with reference to FIGS. 3 and 4.
FIG. 3 shows a schematic configuration diagram, and FIG. 4 shows a system configuration diagram.

First, start the rotation of feed roll 1 at an appropriate timing. Copy paper is sent out one by one from the copy paper tray 2. The fed-out copy paper moves to the registration roll 3, which starts rotating at an appropriate timing.
The leading edge of the copy paper is detected by the sensor 4.

When the sensor 4 detects the leading edge of the copy paper, it sends the signal to the control device (eg, CPU) 8 via the sensor input circuit 7. When the control device 8 confirms that the signal has been sent, it sends a control signal to the clutch drive circuit 11, which is installed between the registration roll 3 and the main motor 10 that powers it. Clutch 5 is controlled off.
When clutch 5 is turned off, registration roll 3
stops rotating, and the copy paper also stops.

Thereafter, when the operation of forming an electrostatic latent image on the drum 6 begins, the clutch 5 is turned on at a timing such that the front end of the image forming area on the drum 6 coincides with the leading edge of the copy paper. Ru. As a result,
The developed electrostatic latent image is copied onto a predetermined position on copy paper.

FIG. 5 is a diagram showing the timing of the above-described operation. Let _t1 be the time when the leading edge of the copy paper conveyed from sensor 2 arrives at sensor 4, then sensor 4
The detection signal a becomes H level. This detection signal a
is sent to the control device 8, and under the control of the control device 8, the clutch steady excitation circuit 11a of the clutch drive circuit 11 is deenergized as shown. Then, the clutch 5 is turned off, and the rotation of the registration roll 3 is stopped. At this time, the registration roll 3 completely stops after a certain time delay (Δt ₁ ).

Next, when the operation of forming a latent image on the drum 6 begins, the clutch steady excitation circuit 11a is energized again at an appropriate timing (time _t2 ). Then, the clutch 5 is turned on, the drive of the main motor 10 is transmitted to the registration roll 3, and the registration roll 3 resumes rotation. At this time, the clutch 5 reaches a constant rotational speed after a certain time delay (Δt ₂ ). At time _t3 , the copy sheet completely passes the sensor 4.

(Problems to be solved by the invention) The above-mentioned conventional techniques had the following problems.

As described above, in the conventional paper feed control device, when the sensor 4 detects the copy paper, the clutch constant excitation circuit 11a of the clutch drive circuit 11 is de-energized by the action of the control device 8, while the latent image is left on the drum. When the operation of forming the magnet starts, excitation is restarted at an appropriate timing related to this. Therefore, a delay occurs when the registration roll stops and rotates again, and the delay times Δt ₁ and Δt ₂ tend to vary each time copying is performed. As a result, the accuracy of alignment between the image forming area on the drum and the copy paper deteriorates.

With conventional equipment, the process speed is 200 to 250
Even at a low speed of about mm/sec, an error of ±2 mm (hereinafter referred to as registration variation) occurs. This resistor has the problem of being amplified and becoming even larger when the process speed increases to around 500 mm/sec, making it unusable for high-speed machines.

Furthermore, in the conventional device, when the clutch 5 is off, that is, from time t ₁ to t ₂ in FIG. They are arranged so that they are spaced apart or come into frictional contact. Therefore, if power is transmitted to the registration roll 3 through the clutch for some reason, the registration roll 3 will idle. In this case, there was a problem in that the copy paper was sent out regardless of the timing being appropriate, resulting in copy errors.

The purpose of the present invention is to eliminate the problems of the prior art described above, and to improve the accuracy of alignment between the drum latent image and the recording paper, that is, the registration variation to about ±0.5 mm.
As a result, it is possible to provide a paper feed control device that can be used even in high-speed machines with a process speed of about 500 mm/sec.

The present invention has been made to solve the above-mentioned problems.

(Means and operations for solving the problems) In order to solve the above problems, the present invention provides a paper feed control device that transmits the drive of a motor to the registration rolls via a clutch. a clutch steady excitation circuit and a clutch overexcitation circuit that drive the register roll, a brake that applies braking to the registration roll, and a brake steady excitation circuit and a brake overexcitation circuit that drive the brake, and which stop or rotate the registration roll. It is characterized in that the registration variation is suppressed to approximately ±0.5 mm by operating each of the over-excitation circuits before operating each of the steady-state excitation circuits during operation.

(Example) The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention.

In the figure, 11b is a clutch overexcitation circuit, and the clutch steady excitation circuit 11a and the clutch overexcitation circuit 11b are selected depending on the function of the control device 8. Further, 12 is a brake drive circuit,
It consists of a brake steady excitation circuit 12a and a brake overexcitation circuit 12b. The brake constant excitation circuit 12a and the brake overexcitation circuit 12b are selectively driven by the control device 8 in the same way as the clutch drive circuit 11. A brake 13 functions to apply a brake to the registration roll 3.
Reference numerals other than these indicate the same or equivalent parts as in FIG. 4.

Next, the operation of this embodiment will be explained with reference to FIG. FIG. 2 shows a timing chart.

When the recording paper is detected by the sensor 4 at time _t1 , the excitation of the clutch constant excitation circuit 11a is released, and the clutch 5, which had been turned on, is turned off. For this reason, the main motor 10
The driving force is no longer transmitted to the registration roll 3, and the rotation speed of the registration roll 3 decreases.

Next, when the delay time T elapses and time _t2 arrives, the brake overexcitation circuit 12b is excited for a short time. As a result, the registration roll 3 is subjected to large braking and stops in a short time. Brake overexcitation circuit 12
When the excitation time b has elapsed and the time _t3 arrives, the brake steady excitation circuit 12a is subsequently excited. This excitation is canceled at time _t4 by a control signal from control device 8, and at time _t5 after delay time T, clutch overexcitation circuit 11b is briefly excited. As a result, the clutch plates of the clutch 5 are firmly connected in a short time, and the driving force of the main motor 10 is quickly transmitted to the registration roll 3. Clutch overexcitation circuit 1
When the excitation time 1b has elapsed and time _t6 arrives, the clutch steady excitation circuit 11a is subsequently excited.

Thereafter, the clutch 5 is turned off at an appropriate timing and the registration roll 3 is stopped. and,
When the next copy sheet is fed to the paper transport path by the feed roll, the clutch 5 is turned on at an appropriate timing and the registration roll 3 resumes rotation.

Here, the reason why the excitation time of the overexcitation circuits 11b and 12b is shortened is that the overexcitation circuit has a current of 1.8A, for example.
This is to prevent the coil from breaking due to heat since a large current of ~2A is passed through it. Incidentally, the current flowing through the clutch steady excitation circuit 11a and the brake steady excitation circuit 12a is about 0.5A. Also,
The reason why the delay time T is provided is to prevent the positive and negative driving forces from colliding by setting the brake 13 to work after the clutch 5 is completely turned off, or vice versa. It's for a reason.

As described above, according to this embodiment, the clutch over-excitation circuit 11b is added to the clutch drive circuit 11, and the brake drive circuit 12 includes the brake steady-state excitation circuit 12a and the brake over-excitation circuit 12b.
Since this is newly added, the registration roll 3 moves suddenly when the rotation is stopped and when the rotation is restarted. Therefore, variations during this operation, that is, variations in Δt ₁ and Δt ₂ in FIG. 5, are reduced, and the recording paper is stopped almost exactly at the predetermined location after being detected by the sensor. Further, even when the conveyance is restarted, the speed is always the same at almost the same timing.

Furthermore, while the recording paper is stopped, the brake constant excitation circuit 12a is always excited and the registration roll 3 is braked, so even if the drive of the main motor 10 is transmitted to the registration roll 3 for some reason, the registration roll There is no such thing as 3 being idle.

Note that if the time it takes to turn on the transistor that provides the overexcitation voltage is longer due to a circuit failure, a current exceeding the rated value will flow through the brake coil, causing the
The temperature of the brakes will rise rapidly and become dangerous. For this reason, it is preferable to insert a time lag fuse (delay type fuse) between the power supply and the coil to prevent the overexcitation voltage from being applied to the brake for more than a certain period of time.

(Effects of the invention) As is clear from the above explanation, according to the present invention, the following effects are achieved.

(1) When the clutch installed between the main motor and the registration roll is turned on and off, the clutch over-excitation circuit and the brake over-excitation circuit are operated for a short period of time, so that fluctuations when switching the operation of the clutch are reduced. Width is reduced and registration variation is improved. According to this invention, ±
Registration variation of about 0.5mm can be achieved.

(2) When the registration roll is stopped, that is, between time t ₃ and _{time t 4} in FIG. 2, braking is applied to the registration roll, so the registration roll does not idle. Therefore, the copy paper will not be erroneously sent toward the drum during the above period, and the occurrence of copy mistakes can be completely prevented.

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram of an embodiment of the present invention.
Fig. 2 is a time chart showing the operation timing of the main components in Fig. 1, Fig. 3 is a schematic diagram of a conventional paper feed control device, Fig. 4 is a system configuration diagram of the conventional device, and Fig. 5 is its This is a time chart showing the operation timing of the main components. 1...Feed roll, 2...Copy paper tray, 3...Register roll, 4...Sensor, 5...
...Clutch, 6...Drum, 7...Sensor input circuit, 8...Control device, 9...Main motor drive circuit, 10...Main motor, 11...Clutch drive circuit, 11a...Clutch steady excitation circuit, 11
b...Clutch overexcitation circuit, 12...Brake drive circuit, 12a...Brake steady excitation circuit, 12
b...Brake overexcitation circuit.

Claims (1)

[Claims for Utility Model Registration] (1) A paper feed control device that transmits the drive of a motor to a registration roll via a clutch, including a clutch constant excitation circuit and a clutch overexcitation circuit that drive the clutch, and a clutch overexcitation circuit that drives the clutch. It is equipped with a brake that applies braking to the registration roll, and a brake constant excitation circuit and a brake overexcitation circuit that drive the brake, and when the registration roll is stopped or rotated, each of the above-mentioned steady excitation circuits is operated. A paper feed control device characterized by operating an overexcitation circuit. (2) The paper feed control device according to claim 1, wherein the brake is operated during a period when the registration roll is stopped.