JPS6388569A - Copying machine - Google Patents

Abstract

PURPOSE:To eliminate a shift in transfer position by lowering the feed speed of copying paper, the rotating speeds of a photosensitive drum and a fixing roller, and the moving speed of a light source or original plate in synchronous relation before or after the front end of the copying paper being sent out by a resist roller passes by the fixing roller. CONSTITUTION:A main motor begins to rotate at time A and then rotates at a constant rotating speed. The original platen 1, resist roller 9, fixing roller 13, etc., are coupled with the main motor through a clutch and when the clutch operates, they begin to rotate at constant speeds with specific timing delay. At time B, the front end of the copying paper cuts off the optical axis of a sensor 14 and then a start signal S1 is generated to lower the rotating speed of the main motor. The degree of the decrease in the rotating speed of the main motor varies curvedly so as to reduce a shock as much as possible and is so set that the front end of the copying paper is caught by the fixing roller 13 when the rotating speed of the main motor decreases most. Consequently, the position shifting of a transfer image due to the collision of the copying paper after transfer against the fixing roller is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a copying machine whose purpose is to eliminate transfer misalignment that occurs when the leading edge of a copy sheet hits a fixing roller after transfer.

PRIOR ART AND PROBLEMS Conventionally, for example, a copy paper is loosely guided to the fixing roller only by a guide plate or the like without a conveying means such as a so-called conveying belt between the registration roller and the fixing roller. In a simplified copying machine that transports only by the feeding action of registration rollers, when the leading edge of the copy paper after transfer is bitten by the fixing roller, it collides with the fixing roller at a considerable speed, and the impact causes the copying to be delayed. The drawback is that the paper vibrates and the vibrations are transmitted to the transfer section, which tends to cause problems such as transfer misalignment.

Such drawbacks also apply to copying machines equipped with a conveyance belt or conveyance rollers that feed the copy paper downstream of the transfer section, and the above-mentioned impact is particularly large in models with high copying speeds.

OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems associated with the collision of copy paper with the fixing roller, and to eliminate problems such as transfer misalignment.

Structure of the Invention In order to achieve the above-mentioned object, the main means adopted by the present invention is that the above-mentioned method is adopted in a copying machine that discharges copy paper sent out from a registration roller through a transfer section and a fixing roller. Before and after the leading edge of the copy paper being sent out by the registration roller passes the fixing roller, the feeding speed of the copy paper, the rotational speed of the photosensitive drum, the fixing roller, and the moving speed of the light source or document platen are reduced while being synchronized. This is a copying machine related to the above points.

Therefore, the present invention is applicable to both types of copying machines in which the document table is stopped and the light source is moved, and vice versa, as well as copying machines of the type in which the document table is moved and the light source is stopped. In the case where a single motor is used to drive one optical element, a fixing roller, etc., speed adjustment such as If so, the speeds of each of these motors are controlled simultaneously in synchronization.

Note that the timing of the speed change control as described above may be based on the time when the leading edge of the document crosses the optical axis of an optical sensor provided in front of the fixing roller, as shown in the following embodiments, and This may be achieved by programming to perform synchronous control after a certain period of time after the registration rollers start being driven.

Function The copy paper is sent out by the registration rollers, and just before its leading edge reaches the fixing roller, the copy paper feeding speed, the rotation speed of the photosensitive drum, the fixing roller (-) and the moving speed of the light source or document platen are reduced in synchronization. Therefore, the impact force when the leading edge of the copying machine collides with the fixing roller is alleviated, and image disturbance at the transfer section is prevented.

When the copy paper is caught in the fixing roller, the above fixing roller,! The rotation speed of the three-light drum and the pond increases to the original normal speed, and the copy paper after fixing is discharged.

Incidentally, if necessary, the voltage applied to the exposure lamp may be changed in synchronization with fluctuations in the above-mentioned copy paper feeding speed, etc.

Embodiments Next, embodiments embodying the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention. here the first
FIG. 2 is a time chart showing a speed change control state of a copying machine according to an embodiment of the present invention, FIG. 2 is a block diagram showing an outline of a control device for controlling speed changes of the copying machine, and FIG. 1 is a side sectional view showing an overview of the entire copying machine according to an embodiment.

In the following embodiments, first, one main motor is used to move the photosensitive drum, registration roller, transfer roller, and paper ejection roller.
A case in which the document table is moved will be explained.

In such a copying machine, as shown in FIG.
As the original is moved, the original placed on the original platen 1 is exposed and scanned by light #2. In this case, among the light emitted from the light source 2, the light that hits l1iIfa and is reflected passes through mirrors 3° and 36.3C, reaches lens 4, is further reflected by mirror 5, and forms an image on the surface of photosensitive drum 6.

Since the photosensitive drum 6 starts rotating at a predetermined timing with respect to the start of movement of the document table 1, an electrostatic latent image corresponding to the document image is formed on its surface, and this electrostatic latent image is developed. When passing through section 7, toner is attached and visualized.

On the other hand, the copy paper fed from the paper feed cassette 8 stops after being inserted into the registration rollers 9, but the registration rollers 9 start rotating after a predetermined time delay from the start of rotation of the photosensitive drum 6. As a result, the copy paper inserted into the photosensitive drum 6 passes through the transfer section 10 near the surface of the photosensitive drum 6, so that the toner image on the surface of the photosensitive drum 6 is transferred to the copy paper.

The copy paper on which the toner image has been transferred is separated from the photosensitive drum 6 by a separation claw 11, guided by a guide 12,
It is evacuated by the feeding force of the registration roller 9.

This embodiment differs from conventional copying machines in the following points:
First, an optical sensor 1 is installed on the conveying thread path up to the fixing roller 13 where the copy paper is conveyed after the transfer is completed.
4 is provided.

The signal from the sensor 14 is sent to the input section of the microcomputer as well as to the timer 15, as shown in FIG. The timer 15 is started by a signal from the sensor 14, and sends a signal to the microcomputer after a set time. A signal sent directly from the sensor 14 to the microcomputer is a start signal S.
I, and the signal sent from the timer 15 to the microcomputer is assumed to be an end signal S2.

Upon receiving the start tiqs1, the microcombination unit 21 starts the photosensitive drum 6, the registration roller 9. Manuscript stand 1. Fixing roller 13. A signal S3 is sent to the control device 18 of the main motor 17 that drives the discharge roller 16 and the like to instruct the main motor 17 to reduce its rotational speed. This reduces the rotational speed of the main motor 17.

That is, as shown in FIG. 1, the main motor starts to rotate at a certain time, and then rotates at a constant rotation speed. Manuscript stand 1. Photosensitive drum 6, registration roller 9. The fixing roller 13 and the like are connected to the main motor 17 via clutches (not shown), and when these clutches are activated, they start rotating at a constant speed after a delay of a predetermined timing.

At time B, as described above, the leading edge of the copy paper is detected by the sensor 14.
This causes the start signal S1 to be issued and the rotational speed of the main motor to decrease. The degree of decrease in the rotational speed of the main motor is varied in a curved manner to reduce the impact as much as possible, and at the point in time (C) when the rotational speed of the main motor has also decreased by an amount, the leading edge of the copy paper is caught in the fixing roller 13. Set it so that

In this way, when the leading edge of the copy paper is caught in the fixing roller 13, the main motor 17 starts speeding up based on the end signal S2 from the timer 15, and returns to the original predetermined rotation speed again after an appropriate period of time.

Thereafter, at a certain time, the copy paper is discharged from the paper discharge roller 16, and at a subsequent time E, the main motor 15 is stopped.

Incidentally, if necessary, the power supplied to the light source 2 may be controlled from the time of the start signal 31 to the time of output of the end signal S2.For this purpose, the light #control device 19 shown in FIG. , the light source control device W, 19 gradually reduces the power supplied to the light source 9 from the start signal S,
End signal S.

On the contrary, increase gradually.

In the above embodiment, a sensor 14 is provided near the upstream side of the fixing roller 13 in the copy paper conveyance direction, and based on a signal from the sensor 14, the copy paper feeding speed and other copying speeds are synchronously reduced for a certain period of time. However, for example, in a program that drives a microcomputer, the main motor 17 may be shifted to a low speed state after a certain period of time from the start of rotation of the registration roller 9, and then returned to its original state.

Note that if the photosensitive drum 6, document table 1, registration roller 9, fixing roller 13, etc. are each provided with a motor as a separate drive source, depending on the deceleration of the motor that drives the photosensitive drum 6, In synchronization with this, speed change control is performed for other motors at the same ratio.

Further, in the above embodiment, the copy paper is sent to the fixing roller 13 by the feeding force of the registration roller 9, but in the present invention, a conveyor belt, a conveyor roller, etc. This also applies to cases where a conveyance means is provided. In addition, in such a case,
The speed of the conveyor belt and the conveyor roller is changed in synchronization with the fixing roller 13.

Effects of the Invention As described above, the present invention provides a copying machine that discharges a copy paper fed out from a registration roller through a transfer section and a fixing roller, in which the leading edge of the copy paper being fed out by the registration rollers reaches the fixing roller. Before and after passing through
This copying machine is characterized in that the feeding speed of the copy paper, the rotational speed of the photosensitive drum, the fixing roller, and the moving speed of the light source or document table are reduced while being synchronized, so that the copy paper after transfer is fixed. The problem of blurring of the transferred image due to collision with the roller can be solved by the wj-like structure.

[Brief explanation of the drawing]

FIG. 1 is a time chart showing a speed change control state of a copying machine according to an embodiment of the present invention, FIG. 2 is a block diagram showing an overview of a control device for controlling speed changes of the copying machine, and FIG. 1 is a side sectional view showing an overview of an entire copying machine according to an embodiment of the invention. (Explanation of symbols) 1... Original table 2... Light source 6... Photosensitive drum 9... Registration roller 10... Transfer section
13... Fixing roller 14... Sensor
15... Timer 17... Main morph 18... Main motor control device 19... Light source control device S,... Start signal S2... End signal.

Claims (1)

[Claims] 1. In a copying machine that discharges the copy paper sent out from the registration rollers through the transfer section and the fixing roller, the feeding speed of the copy paper is determined before and after the leading edge of the copy paper being sent out by the registration rollers passes the fixing roller. A copying machine characterized in that the rotational speed of a photosensitive drum, a fixing roller, and the moving speed of a light source or document table are reduced while being synchronized.