JPS6023237A - Method of detecting multi-feed of transfer sheet - Google Patents

Abstract

PURPOSE:To reliably detect multi-feed of transfer sheets by disposing detecting means to detect a transfer sheet according to a change of the discharge state of a transfer charger. CONSTITUTION:When a transfer sheet is carried near a transfer charger 10, at a point t1 of time, a signal CD is output to operate a high-voltage power source portion 21, and a detection value Id of a current detecter 20 rises up. Supposing that at a point t2 of time, the transfer sheet reaches the transfer charger 10, and at a point t3 of time, the transfer sheet goes through the transfer charger, the detection value Id is changed as shown by a broken line L1 in case of one transfer sheet and as shown by a one- dotted line L2 in case of two transfer sheets. This results from the effect that the moving transfer sheet advances into a discharge path between the transfer charger 10 and a belt photoreceptor, and electric charge produced by discharging adheres to the transfer sheet to decrease electric charge supplied to the belt photoreceptor 1, so that the discharge state remarkably changes depending upon the existence and non-existence of a transfer sheet. At a control portion, during a point t2 of time to t3, the detection value Id is compared with a predetermined value Ir, and if the detection value Id is smaller than the predetermined value Ir, it is judged that transfer sheets are multi-fed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for detecting double feeding of transfer paper in a copying machine or the like that uses a transfer charger as a transfer means.

[Prior Art] An electrostatic copying machine that forms a copy image using an electrophotographic process and transfers the image to transfer paper using a transfer charger is
This image recording process is widely used, and in recent years, this image recording process has also been applied to recording devices such as facsimile machines and printers.

In such a recording apparatus, sheet-shaped transfer paper is normally fed out one by one from a transfer paper stacker and conveyed to a transfer section where a transfer charger is located.

As a mechanism for separating and sending out transfer paper one by one, a friction separation machine using a feed-out friction roller and a friction inclined plate (so-called friction pad) is common, but depending on various conditions such as paper type, etc. Separation fails, resulting in a so-called multi-feed situation in which two or more sheets of transfer paper are fed in an overlapping manner.

When such double feeding of transfer paper occurs, even if the image is transferred without jamming the paper, all of the multiple sheets of transfer paper cannot be separated from the photoconductor. Poor cleaning of the photoreceptor due to unseparated transfer paper.
Charger disconnection in the F electrical section and damage to the photoreceptor may occur.

Therefore, conventionally, the following double feed detection means is provided in the single paper conveyance path from the transfer paper stacker to the transfer unit, and when this means detects double feed, it stops the conveyance of the transfer paper and also issues an alarm. I was trying to display it.

(2) A means for measuring the amount of light transmitted through the paper in the conveyance path, and determining that double feeding has occurred when this Revision III value is less than a predetermined value.

(2) Means for measuring the rough distance between the shaft centers of a pair of rollers that transport the transfer paper in the transport path, and determining that double feeding has occurred if this measured value exceeds a predetermined value.

However, such conventional double feed detection means each have the following problems of the 11th order.

■ The types of paper used as transfer paper range from those with a large amount of transmitted light, such as second original drawing paper, to those with a small amount of transmitted light, such as cardboard, and the amount of transmitted light on a single sheet of paper changes over such a wide range. Therefore, it is difficult to determine whether the number of sheets is one or two or more.

Further, it cannot be applied to materials such as cardboard where the transmitted view does not change much even when one or more sheets are used.

■ The measured values are directly affected by the eccentricity and vibration of each roller, and therefore the error is large.

Accurate double feed detection is difficult.

[Objective] The present invention solves the above-mentioned problems, and provides a method for detecting double feeding of transfer paper that can determine double feeding of transfer paper based on changes in the discharge state of a transfer charger and reliably detect double feeding of transfer paper. [Configuration] Hereinafter, the embodiments of the present invention will be revised with reference to the accompanying drawings) I
Explain to ll.

FIG. 1 shows a copying machine according to an embodiment of the present invention.

In the figure, 1 is a belt photoreceptor, 2 and 3 are belt l
-1i5 A roller that drives the photoconductor 1 in the direction of the arrow; 4 an optical system that optically scans the document and exposes the belt photoconductor 1; 5 develops the electrostatic latent image on the belt photoconductor 1 with toner. A developing device, 6 a transfer paper, 7 a pickup roller for sending out the transfer paper 6, 8 a pair of rollers for conveying the transfer paper 6 to the transfer section,
9 is a guide plate, 10 is a transfer charger for transferring the toner image on the belt photoreceptor 1 onto the transfer paper 6, 11 is a guide plate for guiding the transfer paper 6 whose curvature is calculated from the belt photoreceptor weight, and 12 is the transfer paper a fixing device for fixing the toner image on 6; 13;
1. is a roller pair that conveys the transfer paper 6 after fixing; and 1. /
I is 1 to lay for accumulating the transfer paper 6 after fixing.

15 is a static elimination lamp for removing residual charges on the surface of the belt photoreceptor 1; 16 is a cleaner for removing residual l/toner on the surface of the belt photoreceptor 1; and 17 is a belt photoreceptor 1.
This is a charger that charges the surface uniformly.

As shown in FIG. 2, the photoreceptor 1 includes a transparent flexible base material 1a such as a polyester film (so-called Mylar), and a conductive layer 1b formed by vapor-depositing aluminum or the like on the material 1a. The photoreceptor material layer 1c is formed by vapor-depositing selenium or the like on the conductive layer 1b.

Furthermore, a conductive layer 1d made of carbon paint or the like is formed on one side end of the belt photoreceptor 1, and as shown in FIG.
This conductive J31d is grounded via a conductive brush 19 made of carbon fiber or the like.

In this embodiment, the discharge state of the transfer charger 1o is detected by the change in the current flowing through the belt photoreceptor 1, and the current detection section is shown in FIG.

As shown, a current detector 20 is connected between the brush 19 and ground.
is inserted, and its current value Id is output to a control section (not shown) (which controls and monitors each process and each device of the copying machine). Further, an operation command signal CD is applied to the high-voltage power supply section 21 from the control section, and while this signal CD continues, the high-voltage power supply section 21 is operated, and the transfer voltage is applied to the bell 1 from the electrode 10a of the transfer charger 10. supplied to the body 1.

Now, when the copying machine starts operating and the transfer paper is conveyed to the vicinity of the transfer charger 10, the signal C is sent from L1 at this point.
D is output, the high voltage power supply unit 21 operates, and the current detector 2
The detected value Id of 0 rises and falls as shown in FIG.

Assuming that the transfer paper arrives at the transfer charger 10 at time L2 and passes through the transfer charger 10 at time L3, the detected value d will be as shown by the broken line L1 if there is only one sheet of transfer paper, or as shown by the dashed-dotted line if there are two sheets of transfer paper. It changes like L2.

This phenomenon occurs when the moving transfer paper enters the discharge path between the transfer charger 10 and the belt photoreceptor 1, and the electric charge caused by the discharge is deposited on the transfer paper and removed, and as a result, the photosensitive material is transferred to the belt 1. This occurs because the charge supplied to the body 1 decreases and the discharge state changes greatly compared to when there is no transfer paper.

Further, since more charges are removed when there are two or more sheets of transfer paper than when there is one sheet of transfer paper, the detected value Id becomes smaller.

, Therefore, by comparing the detected value Id with the predetermined value Ir between time points L2 and L3 in the control unit, the detected value Id
If it becomes smaller than the predetermined value Ir, it can be determined that the transfer paper has been fed in duplicate.

(No. 6 C11 is stopped at time 4 after the transfer paper has completely passed through the transfer charger 10, the operation of the high voltage power supply section 21 is stopped, and the detection value Id also falls. If the detected value d does not reach , the detected value d becomes a constant value as shown by the solid line in the figure.

In this way, you can easily check that the transfer paper has been fed multiple times.
Moreover, TI(C) can actually be detected.

By the way, there are two types of high-voltage power supply section 21 for the transfer charger, a constant voltage type and a constant current type, and there are two types of transfer paper: one that reduces the load on the transfer charger 10, and one that reduces the load on the transfer charger 10.
There are two types: one that increases the size.

Therefore, in addition to the two consecutive embodiments, double feeding of transfer paper can be detected by the method described below.

If the transfer paper reduces the load on the transfer charger 10,
Double feeding of transfer paper can be detected as follows.

That is, when the transfer paper is located between the transfer charger 10 and the belt photoreceptor 1, equivalently, the impedance between the transfer charge-\bow 0 and the bell 1-photoreceptor 1 decreases.

Therefore, when the high voltage power supply section 21 is of a constant voltage type, the total current Io (see FIG. 4) increases. Further, in the case of a constant current type, the voltage VO increases and the current Tc flowing through the casing 10b of the transfer charger 10 increases accordingly.

Such increments in the total current Io, voltage VO, and current Ic are larger when there are two or more sheets of transfer paper than when there is one sheet of transfer paper. Therefore, when the total current Io, voltage V0, and current Ic exceed their respective predetermined values, it can be determined that the transfer paper has been fed double.

Further, if the transfer paper increases the load on the transfer charger 10, double feeding of the transfer paper can be detected as follows.

That is, in this case, if the transfer paper is placed between the transfer charger 10 and the belt photoreceptor 1, the impedance between the transfer charger 10 and the belt 1-photoreceptor 1 will equivalently increase.

Therefore, when the high voltage power supply section 21 is of a constant voltage type, the total current Io decreases. Furthermore, in the case of a constant current type, the voltage Vo decreases and the current Ic also decreases.

Such a total current]0. The decrease in voltage Vo and current 1c is larger when there are two or more transfer sheets than when there is one transfer sheet. Therefore, the total current Io, voltage V.

When the current Ic and the current Ic become smaller than their respective predetermined values, it can be determined that the transfer paper has been fed double.

The above can be summarized in terms of the type of high-voltage power supply section 21 as follows.

When the high voltage power supply unit 21 is of a constant voltage type, the total current To is detected, and when the total current Io exceeds a predetermined range, it is determined that the transfer paper has been fed double.

When the high voltage power supply section 21 is of a constant current type, it detects the voltage vO or the current Ic, and when the voltage vO or the current Ic exceeds the respective predetermined ranges, it is determined that the transfer paper has been fed double.

In this way, whether the high-voltage power supply section 21 is of a constant voltage type or a constant current type, it is possible to reliably detect that the transfer sheets are fed in duplicate.

In the above explanation, the photoreceptor is belt-shaped, but this is not the only option. Even when a drum photoreceptor is used, double feeding of transfer paper can be detected in the same way. can. Furthermore, it goes without saying that the present invention is not limited to copying machines.

[Effects] As explained above, according to the present invention, double feeding of transfer paper is detected based on changes in the discharge state of the transfer charger, so the advantage is that double feeding can be detected more reliably than conventional devices. get.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a copying machine according to an embodiment of the present invention, FIG. 2 is a sectional view illustrating a groove path of a belt photoreceptor, and FIG.
The figure is a perspective view illustrating a belt photoreceptor, FIG. 4 is a block diagram illustrating an example of a detection section according to an embodiment of the present invention, and FIG.
The figure is a waveform diagram showing an example of a detection mode. 1...bell 1-photoreceptor, 19...brush, 2o...
Current output device, 21...High voltage power supply section. Figure 7 Figure 2 Figure 3 Id Figure 4 1゜ Figure 5 Id (pA)

Claims (1)

[Scope of Claims] (1) In a transfer paper double feed detection method for a recording device in which a copy image is formed on a photoreceptor by an electrophotographic process and the image is transferred from the photoreceptor to a transfer paper by a transfer charger, the discharge of the transfer charger is performed. A method for detecting double feeding of transfer paper, characterized by detecting double feeding of transfer paper based on a change in state. (2. In claim 1, the change in the discharge state is detected by the current flowing through the photoreceptor, and when the detected value becomes less than a predetermined value, it is determined that the transfer paper is being fed double. A characterized transfer paper double feeding detection method. (3) In claim 1, a change in the discharge state is detected by the voltage of a high-voltage power supply supplied to the transfer charger, and the detected value falls within a predetermined range. A method for detecting double feeding of transfer paper, characterized in that the double feeding of transfer paper is determined when the amount exceeds 1. A method for detecting double feeding of transfer paper, characterized in that when the detected value exceeds a predetermined range, it is determined that double feeding of transfer paper has occurred. A method for detecting double feeding of transfer paper, characterized in that a change in the amount of transfer paper is detected by a current supplied to a transfer charger, and when the detected value exceeds a predetermined range, it is determined that double feeding of transfer paper has occurred.