JPS585756A - Method and device for separation of transfer paper - Google Patents

Abstract

PURPOSE:To make separability of transfer paper stable by measuring the volume resistance of transfer paper with the relation rho=K/Id(K is a constant) from the electric current I flowing in the thickness direction of the transfer paper and the thickness (d) of the transfer paper and controlling electric dischargers with the signal obtained in this way. CONSTITUTION:A strain gage 15 measures the extent at which the shaft 9a of a roller 9 is moved by the entry of transfer paper 16 between rollers 8 and 9, thereby measuring the thickness of the transfer paper. A resistor 13 detects the electric current I flowing in the transfer paper between the rollers 8 and 9 in its thickness direction as voltage. A volume resistivity converter 14 determines the resistance rho of the transfer paper by the relation rho=K/(A,B) from the output B proportional to the thickness (d) of the transfer paper from the gage 15 and the current detection output A by the resistor 13. A corona discharger 1 for transfer and a corona discharger 2 for sepn. are controlled by the output signal of the converter 14. With such arrangement, the sepn. point of the transfer paper is constant and the separability of the transfer paper is stable.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for separating transfer sheets in image forming apparatuses such as copying machines and recording apparatuses.

In copying machines and the like, as shown in FIG. 1, there is a system in which image transfer and transfer paper separation are performed using a transfer corona discharge device 1 and a separation corona discharge device 2.

In this method, the transfer paper is guided by a guide plate 5, an image is transferred from an image carrier 4 such as a photoreceptor by a transfer corona discharger 1, and is separated from the image carrier 4 by a separation corona discharger 2 and conveyed. It is transported by the device 5. Here, there is a method of measuring only the surface resistance of the transfer paper and inputting this measurement signal to the feedback terminal of the power pack (high voltage generator) for driving the corona discharger 1.2 to stabilize the separation of the transfer paper. However, this method only allows the use of specific transfer paper.

The reason for this is that the amount of charge on the transfer paper by the transfer corona discharger 1 differs depending on the type of transfer paper, so the separation corona discharger 2
This is because there may be cases where the charge cannot be removed to the extent that the transfer paper can be separated.

FIG. 2 shows potential changes of different types of transfer papers A and B.

The charge on the transfer paper B is removed by the separation corona discharger 2 to a surprisingly low level of zero, but the charge on the transfer paper A is not removed to substantially zero by the separation corona discharger 2. Therefore, under the same conditions, transfer paper B is separated from image carrier 4, but transfer paper A is not separated from image carrier 4. Differences in separation properties due to different types of transfer paper are also caused by shifts in the separation point due to the speed of the machine, and although there are slight differences depending on the diameter of the image carrier 4, it is possible to increase speed, high sensitivity, and high image quality. Machinery is a phenomenon that is becoming increasingly apparent.

The reason for this is that the amount of charge on the transfer paper during the transfer process differs depending on the volume resistance of the transfer paper, so that some transfer papers are charge-freed during the charge removal process, while others are not. Of course, this varies depending on the usage environment, so setting the conditions is difficult and the setting range is narrow, resulting in an unstable and low-quality machine.

Therefore, instead of measuring the surface resistance of the transfer paper, a method of measuring the volume resistance of the transfer paper has been proposed.

However, this method only detects the current flowing between both ends of the transfer paper, and although the effect of paper thickness is included to some extent, it is not highly accurate. That is, if the applied voltage of the transfer paper is 1 V, the applied current is 9, the paper thickness is d0, the area is S9, the volume resistance is ρ, there is a relationship of -IXd, but in reality I, V,
From the relationship of S, P is substituted and V, S, and d are constants to detect changes in machining, so although the effect of d is taken into account in machining, it is not a highly accurate method. Therefore, the separability of the transfer paper is unstable, and the types of transfer paper that can be used are limited.

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned problems and to provide a method and apparatus for separating a transfer paper in which the volume resistance of the transfer paper can be measured with high accuracy and the separability of the transfer paper is stable.

The present invention will be described below by way of examples with reference to the drawings.

FIG. 5 is a diagram for explaining an example of the present invention.

In the above method, before the transfer paper enters the transfer process, its volume resistance is measured by a volume resistance measuring means and input to the feed puncture terminal F'B of the drive circuit 6.7.

The drive circuits 6 and 7 are power backs that drive the transfer corona discharger 1 and the separation corona discharger 2, and the output of the power back 6 decreases as the volume resistance of the transfer paper increases. As the volume resistance of the transfer paper becomes higher, the power back 7 will come out more and the amount of charge removed by the charge removal corona discharger 2 will increase. Since there is a time difference between the time for measuring the volume resistance of the transfer paper and the transfer and separation steps, a means for correcting this is provided on the feedback input side of the power back 6.7. The volume resistance measuring means measures the volume resistance of the transfer paper from when the transfer paper leaves the paper feeder until it enters the transfer process, and as will be described later in the embodiment shown in FIG. ,
DC constant voltage power supply 10. Resistors 11 to 13, etc. are used.

The volume resistance ρ of the transfer paper and the amount of charge by the transfer corona discharger 1 have a nearly linear relationship, for example, as shown in FIG. , a transfer paper having a volume resistance ρ2 is charged to v2 during the transfer process. Here, if the amount of charge of the transfer paper in the transfer process is constant, the amount of charge and the output of the power back 6 are the fourth
If the relationship ■ shown in the figure is not satisfied, and if we take the transfer paper with the volume resistance ρ1 as a reference, then for the transfer paper with the volume resistance ρ2, it is sufficient to lower the output of the power back 6 to &. As a result of the above, the movement of the charge on the transfer paper is as shown in Fig. 5. The transfer paper having the volume resistance ρ1 serving as a reference is neutralized to a potential of V3 at time t2 and separated as shown by the solid line in FIG. In the case of a transfer paper having a volume resistance ρ2, if the output of the power back 6 is changed in accordance with the volume resistance measurement signal from the volume resistance measuring means, the amount of charge in the transfer process becomes V+, which is the same as that of the transfer paper having a volume resistance ρ1. Also, if the output of the power back 7 is changed according to the volume resistance measurement signal, it will be t2 as shown by the dotted line in Figure 5.
It will be v3 at this point. In an actual machine, if the output of the power back 6 is reduced too much, transfer defects may occur even on transfer paper with high volume resistance, and if the amount of charge removed by the separation corona discharger 2 is increased too much, the separation corona discharger 2 Therefore, it is better to control the output of both the upper and lower parts of the power pack 6° and 70 using the volume resistance measurement signal.

By doing the above, various transfer papers can be separated in the same way because the separation point is constant, and the separation width (corresponding to 1, ~t2), which conventionally varied depending on the type of transfer paper and environment, is constant and wide. It can be transferred even if the characteristics of the transfer paper change.

Since the correction is made at the time of separation, the transfer paper can be used freely.

FIG. 6 shows an embodiment of the present invention, and an off-line diagram shows a part thereof. The rollers 8 and 9 are connected to a constant voltage power supply 10 of +400V via resistors 11 to 13 in series. The reason why the power source is a constant voltage power source is to simplify the conversion constant of the volume resistance converter 14. The rollers 8 and 9 are conductive metal rollers, one of which 9 is movable in a direction away from the other 8, and a spring (not shown) provides a tendency for the rollers 8 and 9 to come into pressure contact with each other. The reason why roller 9 is made movable is that the thickness of the transfer paper changes so that the contact area between the transfer paper and rollers 8 and 9 remains constant. The strain gauge 15 is arranged to be driven by the shaft 9a of the roller 9, and measures the amount of movement of the shaft 9a of the roller 9 when the transfer paper 16 is carried between the rollers 8 and 9, thereby determining the thickness of the transfer paper. Measure. The electric current flowing in the thickness direction of the transfer paper between the 16 resistor rollers 8 and 9 is detected as a voltage.
The volume resistance converter 14 uses the output ■ proportional to the thickness d of the transfer paper from the strain gauge 15 and the current detection output from the resistor 13 to convert the resistance ρ of the transfer paper to ρ=τ6 (x: constant) using a relational expression. Find it with The power pack 6 is a volume resistance converter 14
The output signal is input to the feedback terminal FB, and the output is controlled to decrease if the current flowing through the resistor 13 is small and the thickness of the transfer paper is thin.

When the transfer paper is now carried between the rows 28 and 9, the constant voltage power supply 10 is turned on, and the current flowing through the transfer paper is converted into voltage by the resistor 15, and a signal appears. Further, the roller 9 moves by the thickness of the transfer paper, and the amount of movement is detected by the strain gauge 15, and a signal - appears. This signal source means that the transfer paper is connected to the roller 8,
It is designed to operate only when passing between 9 and 9. The output signal of the volume resistance converter 14 is delayed by a delay circuit (not shown) until the transfer paper reaches the transfer corona discharger 1, and is then applied to the feedback terminal FB of the power back B by the length of the transfer paper.
continues to be input.

According to this example, the separability of the transfer paper became unstable when the type of transfer paper changed or the environment changed (in contrast to D, thin paper such as tracing paper, high temperature and high temperature Even under humid conditions, the number of transfer paper separation defects was completely reduced.However, there were some transfer papers that caused some transfer defects.Therefore, in another embodiment of the present invention, the volume resistance measurement signal was used for transfer papers with low volume resistance. The signal was input to the feedback terminal of the power pack 6, and for transfer paper with high volume resistance, the signal was input to both feedback terminals of the power pack 6 and 7 to prevent a decrease in image density due to transfer failure.

As described above, according to the present invention, the volume resistance ρ of the transfer paper can be calculated from the current ■ flowing in the thickness direction of the transfer paper and the thickness d of the transfer paper.
Since the measurement is performed using the relationship KI a (x' constant), the volume resistance of the transfer paper can be measured with high accuracy. Therefore, by controlling the transfer corona discharger and/or the separation corona discharger using this measurement signal, the separability of the transfer paper can be made stable even if the type of transfer paper or the environment changes.

[Brief explanation of the drawing]

Figures 1 and 2 are diagrams for explaining the conventional method;
Figures 5 to 5 are schematic diagrams for explaining examples of the present invention, Figure 6 is an explanatory diagram of the configuration of an embodiment of the present invention, and the off-line diagram is a partially enlarged view of Figure 6. DESCRIPTION OF SYMBOLS 1... Corona generator for transfer, 2... Corona generator for separation, 6.7... Power pack, 8, 9... Roller, 10... Constant voltage power supply, 11-13...・Resistance, 14
...Volume resistance converter, 15...Strain gauge.

Claims (1)

[Claims] 1. In a transfer paper separation method in which a transfer paper on which an image on an image carrier is transferred by a transfer corona discharger is separated from the image carrier by a separation corona discharger, the thickness of the transfer paper is From the current T flowing in the direction and the thickness d of the transfer paper, the volume resistance ρ of the transfer paper is measured as ρ−, where (X: constant), and this measurement signal is used to activate the transfer corona discharger and/or the separation corona discharger. A transfer paper separation method characterized by controlling an electric device. 2. In a transfer paper separation device that separates the transfer paper on which the image on the image carrier has been transferred by the transfer corona discharger from the image carrier by the separation corona discharger, the transfer paper is conveyed to the transfer position. A pair of rollers arranged in a passage, a thickness measuring means for measuring the thickness d of the transfer paper carried into the pair of rollers, a constant voltage power supply connected to the rollers, and a The resistance R of the transfer paper is measured by the relationship R=Kxa (K: constant) using a means for keeping the electric current flowing through the transfer paper constant, and a signal from this means and the thickness measuring means. A transfer paper separation device comprising: a drive circuit for driving a corona discharger; and/or means for controlling a drive circuit for driving a one-separation corona discharger to stabilize transfer paper separation.