JP2689239B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus such as an electrostatographic copying machine or a facsimile.

[Conventional technology]

As a technique for peeling a sheet adhered to the surface of the photoconductor drum, for example, an indirect peeling type sheet indirect peeling means by an AC charger is provided on the downstream side of the transfer means, and the sheet which cannot be completely peeled by the sheet indirect peeling means. In some cases, a sheet peeling claw for forcibly peeling the sheet from the surface of the photosensitive drum is provided on the downstream side of the sheet indirect peeling means.

According to the above sheet peeling technology, due to deterioration of the discharge state and deterioration of the humidity environment due to the dirt of the charger wire and the charger case of the CA charger, the indirect peeling of the sheet by the AC charger becomes defective, and Even when the sheet attached to the surface of the photoconductor drum cannot be completely peeled indirectly by the CA charger, the sheet can be forcibly peeled by the sheet peeling claw, and the occurrence of jam can be reliably prevented. .

By the way, in the above-mentioned forced peeling by the sheet peeling claw, the shock when the tip of the sheet abuts against the sheet peeling claw is applied to the surface of the photosensitive drum, and the surface of the photosensitive drum is damaged. In addition, there is a situation where it is desirable to avoid peeling with a sheet peeling nail.

Here, in order to prevent the indirect peeling failure of the sheet due to the deterioration of the humidity environment, the humidity sensor detects the humidity of the atmosphere near the transfer unit, and controls the voltage applied to the charger wire of the AC charger. Things are offered.

[Problems to be solved by the invention]

In other words, changes in the humidity environment occur frequently,
The damage to the surface of the photosensitive drum caused by the forced peeling of the sheet due to the deterioration of the humidity environment is unexpectedly large, and it is a problem to ignore it.

However, the factors that cause the indirect peeling failure of the sheet are
It also depends on how dirty the AC charger is and how much the seat itself absorbs moisture. Further, since the humidity environment will eventually improve due to the passage of time, air conditioning, etc., it cannot be said that the sheet peeling is always performed well by the above means. Therefore, in the sheet peeling technique in which the sheet peeling claw is provided on the downstream side of the sheet indirect peeling means, the sheet peeling by the unfavorable sheet peeling claw is continuously performed.

In addition to the above-mentioned AC charger, other means for indirectly peeling the sheet include peeling by irradiation of a lamp, peeling by blowing air, electrostatic peeling by an electrostatic attraction plate, and the like.

The present invention is made in view of the above situation, and grasps the indirect peeling situation of the sheet by the sheet indirect peeling means based on the forced peeling of the sheet, and the situation of this indirect peeling. By using change as a control standard,
It is an object of the present invention to enable indirect peeling of the sheet according to factors that influence peeling, such as a humidity environment.

[Means for solving the problem]

In order to achieve the above object, the present invention is a sheet which cannot be completely peeled indirectly by this sheet indirect peeling means, on the downstream side of a sheet indirect peeling means for indirectly peeling a sheet attached to the surface of a photosensitive drum. In an image forming apparatus provided with a sheet peeling claw for forcibly peeling the sheet from the surface of the photoconductor drum, a sheet indirect peeling means is based on displacement of the sheet peeling claw accompanying contact of the sheet with the sheet peeling claw. Then, the detection means for detecting that the sheet which could not be completely peeled off is forcibly peeled off by the sheet peeling claw, and the signal issued based on the detection of the predetermined forced peeling off of the sheet, the signal output according to the detection means is outputted. Based on the above, a feature is that a control means for controlling the peeling condition of the system involved in the indirect peeling of the sheet is provided.

[Action]

That is, the forced peeling of the sheet by the sheet peeling claw is caused by the deterioration of the humidity environment and the indirect peeling ability of the sheet indirect peeling means.
The sheet peeling condition of the system involved in the indirect peeling of the sheet is detected by detecting the displacement of the sheet peeling claw accompanying the forced peeling of the sheet when the sheet is forcibly peeled, and the detection result is used as a control reference. By controlling the above, the indirect peeling ability of the sheet by the sheet indirect peeling means is always maintained good, and the indirect peeling of the sheet by the sheet indirect peeling means is properly performed.

Here, as a control target and its control mode as a peeling condition for always maintaining a good indirect peeling force of the sheet, in addition to a form of cleaning the AC charger of the example of the sheet indirect peeling means, the AC charger In the form of controlling to increase the output, in the form of controlling the shift bias (difference in ± component ratio of the AC charger in the example of the indirect sheet peeling means) above and below the set value, and in the direction of decreasing the output of the transfer charger. A control mode, a mode in which the light amount of the pre-transfer lamp is decreased, or a mode in which a plurality of these modes are simultaneously controlled can be selected.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an image forming section of an electrostatic photocopier, which is an example of an image forming apparatus, and includes a charging charger 2, an exposure device 3, a developing device 4, and a transfer device around a photosensitive drum 1 which is horizontally mounted. A charger 5 (an example of a transfer unit) and an AC charger (an example of a sheet indirect peeling unit) 6 for indirectly peeling the sheet adhering to the surface of the photosensitive drum 1 downstream of the transfer charger 5. A sheet separating means 7 of a claw separation method for forcibly separating from the surface of the photosensitive drum 1 a sheet which has not been completely separated by the AC charger 6 on the downstream side (first It is provided on the left side in FIG. 1) and above the paper discharge path of the paper discharge conveying device 8, and a cleaning device 9 for separating and collecting the residual toner on the surface of the photosensitive drum 1 is arranged.

The sheet peeling means 7 is configured as follows.
That is, as shown in FIG. 2, the cleaning device 9
On the bottom plate 10 of the cleaning case, brackets 11 each having a vertically elongated hole a are formed so as to hang down from the cleaning drum at a distance in the axial direction of the photoconductor drum 1, and a nail holding shaft is provided in the elongated hole a of the bracket 11. 12 is installed so as to be movable up and down, and a biasing means 13 for biasing the claw holding shaft 12 downward is provided.

Then, at a predetermined sheet peeling timing, the tip of the claw softly abuts on the surface of the photosensitive drum 1 by the rotating means (not shown), and after the sheet has passed the leading edge, it is separated from the surface of the photosensitive drum 1. A plurality of sheet peeling claws 14 for forcibly peeling the sheet attached to the surface of the photosensitive drum 1 by the operation are provided on the claw holding shaft 12.

Then, the peeling ability of the AC charger 6 is deteriorated due to dirt on the charger wire 6a or the charger case 6b,
Due to deterioration of the humidity environment, etc., the sheet attached to the surface of the photoconductor drum 1 in the transfer process in the previous stage is cleaned by the AC charger 6
When the sheet cannot be completely peeled off by the method, as shown in FIG. 3, the sheet adhered to the surface of the photosensitive drum 1 is forcibly peeled off by scooping with the sheet peeling claw 14, and the peeled sheet is also peeled off. The sheet peeling claw 14 is displaced upward (lifted up) to reduce the plunge angle of the claw tip with respect to the surface of the photoconductor drum 1, and the surface of the photoconductor drum 1 is damaged by the sheet peeling claw 14. I made it difficult.

The copying machine according to the present invention is provided with the second sheet peeling claw 14 described above.
The output of the AC charger 6 is changed when the forced peeling of the sheet is performed, with the number of forced peeling of the sheet due to the displacement of the sheet peeling claw 14 caused by the contact of the sheet to the sheet as a control reference, The AC charger 6 is configured to change the indirect peeling ability of the sheet.

Specifically, the cleaning case bottom plate 10 is provided with a sensor (for example, a photo interrupter) S as a detection unit that detects an upward displacement (lifting movement) of the sheet peeling claw 14 when the sheet is forcibly peeled. Means 15 for inputting a signal from the sensor S to count the number of times the sheet is forcibly peeled, and transmitting for issuing a signal when the number of times the sheet forcibly peels per unit time during continuous copying reaches a predetermined number. Means 16 and the transmitting means
There is provided a control means 17 for changing the output of the AC charger 6 based on the signal emitted from 16.

The control means 17 inputs the signal from the transmitting means 16 to increase the sheet peeling force of the AC charger 6 and also increases the sheet peeling force when the signal from the transmitting means 16 is cut off for a predetermined time. It has a control function of reducing the output value to the original value.

According to the above configuration, when the humidity environment is deteriorated or the indirect peeling of the sheet by the AC charger 6 becomes defective and the forced peeling of the sheet is performed several times by the sheet peeling claw 14, the output of the AC charger 6 is output. Since the indirect peeling of the sheet by the AC charger 6 is properly performed, the forced peeling of the sheet by the sheet peeling claw 14 is suppressed.

Then, the sheet peeling force of the AC charger 6 is increased, the indirect peeling of the sheet by the AC charger 6 is improved, and when a predetermined period of time elapses after the forced peeling detection signal of the sheet is not output from the sensor S, the AC
The output of the charger 6 is controlled to the sheet peeling force down side.

In this state, that is, when the output of the AC charger 6 is increased and then the output of the AC charger 6 is decreased, the indirect peeling of the sheet by the AC charger 6 is continued, that is, the indirect peeling failure of the sheet. Is proof of the deterioration of the humidity environment, or the fact that the above output up and down control is repeated is
This is evidence that the indirect peeling ability of the AC charger 6 is reduced.

From this, it is desirable to configure the AC charger 6 to be automatically cleaned on the basis of the result that the above control is repeatedly performed, or the AC charger 6 is automatically cleaned.
It is also effective to display that the charger 6 needs to be cleaned and prompt the cleaning of the AC charger 6.

AC is used as a means 6 for indirectly peeling the sheet.
Although the charger is shown as an example, other than that, a peeling type by irradiation with a lamp, a peeling type by blowing air, or the like can be selected.

Further, as an object of control for increasing the indirect peeling force of the sheet and a control mode thereof, as described above, a mode of changing the shift bias with respect to the AC charger 6,
A mode in which the output of the transfer charger 5 is controlled to be lowered,
A mode in which the light amount of the pre-transfer lamp is controlled to be decreased can be selected, and, of course, a mode in which a plurality of these modes are simultaneously controlled can also be selected.

Furthermore, when the paper discharge and transport device 8 has a separation fan,
The load on the separation fan can be reduced.

Further, the displacement of the sheet peeling claw 14 may be managed by time. That is, the detection time by the detection means is accumulated, and the accumulated forced peeling time of the sheet is used as the control reference.
Further, the contact force of the sheet with respect to the sheet peeling claw 14 increases as the indirect peeling ability of the sheet decreases, and the displacement time of the sheet peeling claw 14 also increases. It is also possible to set the reference value by paying attention to that fact and to issue the cleaning signal based on the signal detected when a time longer than that is detected.

〔The invention's effect〕

As described above, the present invention was made by focusing on the fact that the forced peeling of the sheet by the sheet peeling claw is caused by the deterioration of the humidity environment and the indirect peeling ability of the sheet indirect peeling means. Therefore, the displacement caused by the number of times the sheet peeling claws come into contact with the sheet peeling claws when the sheet is forcibly peeled off, or the displacement due to the strong (longer) contacting force is detected by the detection means. Based on the control standard, by controlling the peeling condition of the system involved in the indirect peeling of the sheet to the side where the sheet peeling is favorably performed,
The indirect peeling of the sheet by the sheet indirect peeling means can be properly performed while the forced peeling of the sheet by the sheet peeling claw is suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional view showing an image forming section of an electrostatographic copying machine,
FIG. 2 is a perspective view of a second sheet indirect peeling means for forcibly peeling the sheet, and FIG. 3 is an operation explanatory view of the sheet peeling claw when the sheet is forcibly peeled. 6 ... Sheet indirect peeling means for indirectly peeling a sheet, 14 ... Sheet peeling claw, 15 ... Counting means, 17 ...
... Control means.

Claims (1)

(57) [Claims] 1. A sheet which has not been completely peeled indirectly by the sheet indirect peeling means is forced to the downstream side of the sheet indirect peeling means for indirectly peeling the sheet attached to the surface of the photosensitive drum. In an image forming apparatus provided with a sheet peeling claw for peeling, a sheet that cannot be completely peeled by a sheet indirect peeling means based on displacement of the sheet peeling claw accompanying contact of the sheet with the sheet peeling claw Is provided with a detection means for detecting that the sheet has been forcibly peeled by the sheet peeling claw, and a control means for controlling the peeling condition of the system involved in the indirect peeling of the sheet by a signal generated based on the detection of the predetermined sheet forced peeling. An image forming apparatus characterized by being provided.