JPH11119564A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the electrification efficiency of the inner electrifier of a transferring device. SOLUTION: This device is provided with a rotation detecting sensor 303 detecting the rotation of a transfer drum 5a and a connection plate detecting sensor 306 detecting that a transfer sheet connection plate 5i and the inner electrifier 5d are at a position where they are opposed to each other, and when a connection plate detected signal is outputted, the signal is inputted to a controlling part 301, so that the bias output from a high voltage power source 302 to the inner electrifier 5d is inhibited. A distance between the transfer sheet and the inner electrifier 5d is reduced regardless of an insulated distance between the connection plate 5i and the inner electrifier 5d, so that the electrification efficiency is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art As a conventional color image forming apparatus, a toner image formed on a photosensitive drum as an image carrier is transferred onto a recording material electrostatically attracted onto a transfer drum as a recording material carrier by a transfer brush or the like. 2. Description of the Related Art There is known a transfer device having a transfer device of a type in which transfer is performed by a transfer bias from a transfer unit.

This transfer device has, in addition to the above-described transfer drum and transfer brush, a suction brush for electrostatically adsorbing a recording material, a suction roller facing the suction brush, an inner charger, and an outer charger. Then, a transfer sheet made of a dielectric material and carrying a recording material is laminated on a connecting plate, and is integrally stretched in a cylindrical shape in the peripheral opening area of the transfer drum that is rotatably supported. I have. As the transfer sheet, a dielectric sheet such as a polycarbonate film is used.

[0004]

By the way, the connecting plate of the transfer drum and the inner charger have a positional relationship as shown in FIG.

As described above, the transfer drum 5a has the transfer sheet (supporting sheet) 5f and the connecting plate 5i, and the transfer sheet 5f is laminated on the connecting plate 5i and is integrally stretched. Then, as the transfer drum 5a rotates,
The spatial distance between the inner charger 5d disposed inside the transfer drum 5a and the transfer drum 5a depends on the area where the inner charger 5d directly faces the transfer sheet 5f, that is, the position B where the inner charger 5d does not face the connecting plate 5i. The charging device 5d differs from the region indirectly facing the transfer sheet 5f via the connecting plate 5i, that is, the position A facing the connecting plate 5i. That is, the spatial distance d when the inner charger 5d is located at the non-opposing position B.
Naturally, the spatial distance d2 when located at the opposing position A is closer than 1 due to the connecting plate 5i.

While the transfer sheet 5f is an insulator, the connecting plate 5i is a conductor and is connected to the frame ground of the apparatus. In order to increase the charging efficiency of the inner charger 5d, it is desirable that the spatial distance d1 be as close as possible within a range where the insulation distance from the connecting plate 5i can be maintained. Therefore, the connecting plate 5i is connected to the connecting plate protection sheet 5j made of an insulator.
Covered with an insulating material.

However, in order to further increase the charging efficiency of the inner charger 5d, the spatial distance d1 must be reduced or
Alternatively, a method of increasing the voltage applied to the inner charger 5d is conceivable. However, in order to secure the insulation distance, these are opposite conditions, and there is a limit in improving the charging efficiency.

Accordingly, a main object of the present invention is to provide an image forming apparatus capable of increasing the charging efficiency of a charger relating to a transfer device.

Another object of the present invention is to provide an image forming apparatus capable of safely protecting a transfer device even when an abnormality occurs.

[0010]

The above object is achieved by an image forming apparatus according to the present invention. In summary, the present invention provides:
A rotatable image carrier, exposure means for exposing the image carrier with an image signal, developing means for developing a toner image on the exposed latent image on the image carrier, and the same as the image carrier. In an image forming apparatus comprising: a recording material carrier that carries a recording material on which a final output image is recorded, and a transfer unit that transfers a toner image on the image carrier to the recording material. Means for detecting whether or not the recording material carrier is rotating, and means for stopping power supply to a charger for applying a high voltage to the recording material carrier in accordance with a result of rotation detection of the recording material carrier. An image forming apparatus comprising:

The recording material carrier is stretched in the peripheral opening area, and a dielectric carrier sheet for carrying the recording material is connected to both ends of the carrier sheet on the peripheral surface of the recording material carrier. A connecting plate of a conductor to be grounded, wherein the charger is an inner charger that is disposed inside the recording material carrier and applies a high voltage to the carrier sheet, and further includes the inner charger and the connecting plate. Has a connecting plate detecting means for detecting whether or not the inner charging device is at the opposing position, and according to a detection result by the connecting plate detecting device, when the inner charging device and the connecting plate are at the opposing position, the inner charging device It is preferable to prohibit power supply to the power supply.

The high-voltage power supply for supplying a high voltage to the inner charger has a timer circuit which is reset by an output prohibition signal from the connection detecting means or an output control signal from the device control unit. It is preferable to stop the high voltage output of the high voltage power supply unit after the predetermined time has been counted.

The high-voltage power supply unit has means for detecting that a high voltage is being output, and when the high-voltage output detection signal is being output and the recording material carrier rotation detection signal is not being output at the same time. Preferably, the main power supply of the apparatus is forcibly shut off instantaneously or after a predetermined time.

At least one means for detecting the leading edge position of the recording material on the recording material carrier, and means for detecting that the recording material carrier is rotating based on these recording material leading edge position detection signals. And a means for detecting a position where the connecting plate and the inner charger face each other by using these recording material tip position detection signals.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

Embodiment 1 Embodiment 1 of the present invention will be described with reference to FIGS. First, the color image forming apparatus of the present embodiment will be described with reference to FIG.

In FIG. 1, the color image forming apparatus (digital color copying machine) of the present embodiment has a digital color image reader section at the top and a digital color image printer section at the bottom.

In the reader section, the original 30 is placed on an original platen glass 31 and is exposed and scanned by an exposure lamp 32 so that a reflected light image from the original 30 is condensed on a full-color sensor 34 by a lens 33 to form a color image. Obtain a decomposed image signal. The color-separated image signal is processed by a video processing unit (not shown) through an amplification circuit (not shown) and sent to a printer unit.

In the printer section, a photosensitive drum 1 as an image carrier is rotatably supported in the direction of an arrow. Around the photosensitive drum 1, a pre-exposure lamp 11, a corona charger 2, a laser exposure optical system 3, and a potential sensor 12 are provided. , Four developing units 4y, 4c, 4m, and 4bk of different colors, an on-drum light amount detecting unit 13, a transfer device 5, and a cleaning unit 6 are arranged.

In the laser exposure optical system 3, an image signal from a reader unit is converted into an optical signal by a laser output unit (not shown), and the converted laser light is reflected by a polygon mirror 3a, and a lens 3b and a mirror. 3c, and is projected on the surface of the photosensitive drum 1.

When forming an image on the printer unit, the photosensitive drum 1
Is rotated in the direction of the arrow to uniformly charge the photosensitive drum 1 after the charge is removed by the pre-exposure lamp 11 by the charger 2, and irradiates the light image E for each separation color to form a latent image.

Next, by operating a predetermined developing device, the latent image on the photosensitive drum 1 is developed, and a toner image based on resin is formed on the photosensitive drum 1. The developer is an eccentric cam 2
The operations of 4y, 24c, 24m, and 24Bk make it possible to selectively approach the photosensitive drum 1 according to each separation color.

Further, the toner image on the photosensitive drum 1 is
The image is transferred from a recording material cassette 7 to a recording material supplied to a position facing the photosensitive drum 1 via a transport system and a transfer device 5.

In the present embodiment, the transfer device 5 includes a transfer drum 5a as a recording material carrier, and a transfer brush 5 as a transfer unit.
b, a suction brush 5c for electrostatically adsorbing the recording material, a suction roller 5g opposed to the suction brush 5c, a transfer drum 5
A transfer sheet (which is made of a dielectric material and bears a recording material) is provided in the peripheral opening area of the transfer drum 5a which has an inner charger 5d and an outer charger 5e for neutralizing a, and is rotatably supported. The supporting sheet 5f is laminated on the connecting plate 5i to be integrally stretched in a cylindrical shape. The transfer sheet 5f uses a dielectric sheet such as a polycarbonate film.

As the transfer drum 5a is rotated, the toner image on the photosensitive drum 1 is transferred onto a recording material carried on a transfer sheet 5f by a transfer brush 5b.

As described above, a desired number of color images are transferred to the recording material sucked and conveyed to the transfer sheet 5f to form a full-color image.

In the case of forming a full-color image, when the transfer of the toner images of the four colors is completed in this way, the recording material is separated from the transfer drum 5a by the action of the separating claw 8a, the separating push-up roller 8b and the separating charger 5h. Roller fixing device 9
The paper is discharged to the tray 10 via the.

On the other hand, the post-transfer photosensitive drum 1 is subjected to the image forming process again after the residual toner on the surface is cleaned by the cleaning device 6.

When images are formed on both sides of a recording material,
Immediately after the fixing unit 9 is ejected, the transport path switching guide 19 is driven, and once guided to the reversing path 21a via the transport vertical path 20, the rear end of the sheet fed by the reverse rotation of the reversing roller 21b is moved to the top. And is retracted in the direction opposite to the direction in which the sheet is fed, and stored in the intermediate tray 22. Thereafter, an image is formed on the other surface again by the above-described image forming step.

The brush 14 is opposed to the brush 14 via the fur brush 14 and the transfer sheet 5f in order to prevent scattering of powder on the transfer sheet 5f of the transfer drum 5a and adhesion of oil on the recording material. Cleaning is performed by the action of the backup brush 15 and the backup brush 17 facing the roller 16 via the oil removing roller 16 and the transfer sheet 5f. Such cleaning is performed before or after image formation, and at any time when a jam (paper jam) occurs.

In this embodiment, the eccentric cam 25 is operated at a desired timing, and the cam follower 5k integrated with the transfer drum 5f is operated.
The gap between the transfer sheet 5a and the photosensitive drum 1 can be set arbitrarily. For example, during standby or when the power is off, the interval between the transfer drum 5a and the photosensitive drum 1 is increased.

Next, features of the present invention will be described with reference to the block diagram of FIG.

A rotation detection sensor 303 for detecting rotation of the transfer drum and a rotation detection flag 304 are arranged in the transfer drum 5a, and a rotation detection signal generator 305 generates a rotation detection signal from the output of the rotation detection sensor 303. I do.

In addition, a connection plate detection sensor 306 and a connection plate detection flag 307 are provided to detect that the transfer sheet connection plate 5i and the inner charger 5d are at opposing positions.
A connection plate detection signal generator 308 generates a connection plate detection signal from the output of the connection plate detection sensor 306.

The connection plate detection signal is input to a control unit 301 for controlling the entire apparatus, and is used as a signal for inhibiting remote control of the high voltage power supply 302. The control unit 301 remotely controls the high-voltage power supply 302 according to other conditions and sequences in the image forming process of the entire apparatus.

Timer circuit 309 inside high voltage power supply 302
Is reset when the high-voltage remote signal from the control unit 301 changes from off to on, as shown in FIG. That is, the transfer drum 5a makes at least one rotation,
The timer circuit 309 is reset each time the connection plate detection signal is input to the control unit 301. As shown in FIG. 3B, if an abnormal state in which the remote signal remains on due to some failure continues, the timer circuit 309 counts a predetermined time, disallows the remote signal from the control unit 301, The high voltage output is stopped by itself, and an error signal is generated to the control unit 301. The control unit 301 can stop the operation of the entire apparatus by an error signal, display an error on an operation panel or the like of the apparatus, and notify a user of an abnormal state.

The high voltage power supply 302 outputs the rotation detection signal 30
5 and the connection plate detection signal 308, the transfer drum 5a
Is rotated and the connection plate 5i and the inner charger 5d are not at the opposing positions, a high voltage output permission signal is given.
As shown in FIG. 4B, when the rotation of the transfer drum is stopped, or when the rotation detection signal is not output in spite of the rotation, the high-voltage output is immediately disabled and stopped. .

Further, the high voltage power supply 302 generates a monitor signal indicating that a high voltage is being output regardless of the state of the remote signal. As shown in FIG. 5B, if the monitor signal is turned on and the rotation detection signal is turned off due to some failure, an error signal is generated and the error signal is transmitted to the control unit 301.

When the error state continues for a predetermined time, the timer 312 counts it, and the main switch 310
The main power supply of the entire apparatus is forcibly shut off by turning off the power supply. At this time, since the control unit 301 stores the fact that the error signal has been received in the battery backed up before the main power supply is cut off, the control unit 301 can know what caused the main power supply to be cut off. .

Table 1 below shows a list of the security ensuring means and the detection method of the present embodiment.

[0041]

[Table 1]

In this embodiment, the three types of security means are:
The operation is controlled in accordance with the detection results from the two detection means.

As described above, in this embodiment, the rotation of the transfer drum is detected, and the opposing position of the connecting plate and the inner charger is detected to remotely control the high voltage output. High-voltage output can be stopped, which makes it possible to shorten the distance between the transfer sheet and the inner charger, regardless of the insulation distance between the connecting plate and the inner charger, improving the charging efficiency of the inner charger Can be done.

Further, by providing a timer circuit in the high-voltage power supply unit using a remote signal as a reset signal, if a normal remote signal does not come for a predetermined time or more, the output can be stopped by itself, and some trouble occurs. Can be safely stopped or shut off even if the signal is no longer generated normally.

Embodiment 2 Next, Embodiment 2 of the present invention will be described with reference to the block diagram of FIG.

In the image forming process according to the present embodiment, the transfer drum 5
The three sensors for detecting the position of “a”, the ITOP-A sensor 401, the ITOP-B sensor 403, and the ITOP-C sensor 405, and the flags 402 and 40 corresponding thereto, respectively.
4 and 406 are arranged in the transfer drum 5a. In the digital full-color copying machine of this embodiment, these three I
The operation start timing and the like of the apparatus are generated based on the image tip signal from the TOP sensor.

At the same time, as long as the transfer drum 5a is rotating at a normal speed, signals from these ITOP sensors are generated at a predetermined cycle.

The rotation detection signal 407 is output from these three ITOs.
Based on signals from the P sensors 401, 403, and 405, it is detected that the transfer drum 5a is rotating normally, and a high voltage output permission signal is given to the high voltage power supply unit 302.

The control unit 301 controls these three ITOs.
Based on the signals from the P sensors 401, 403, and 405, the positional relationship between the connection plate 5i and the inner charger 5d is calculated and used as a signal for prohibiting remote control of the high-voltage power supply 302. The control unit 301 remotely controls the high-voltage power supply 302 according to other conditions and sequences in the image forming process of the entire apparatus.

Timer circuit 309 inside high voltage power supply 302
Is reset when the remote signal from the control unit 301 changes from off to on. That is, the timer circuit 309 is reset each time the transfer drum 5a makes at least one rotation and the connection plate detection signal is input to the control unit 301.
If the remote signal remains on due to some failure, the timer circuit 309 counts a predetermined time, disables the remote signal from the control unit 301, stops the high-voltage output by itself, and controls Part 301
Generates an error signal. The control unit 301 stops the operation of the entire apparatus in response to the error signal, displays an error on an operation panel or the like of the apparatus, and notifies the user of an abnormal state.

The high voltage power supply 302 outputs the rotation detection signal 30
5 and the connection plate detection signal 308, the transfer drum 5a
Is rotated, and when the connecting plate 5i and the inner charger 5d are at opposing positions, a permission signal for high voltage output is given.

Further, the high voltage power supply 302 generates a monitor signal indicating that a high voltage is being output regardless of the state of the remote signal. If the monitor signal is turned on and the rotation detection signal is turned off due to some failure, an error signal is generated and the error signal is transmitted to the control unit 301. When the error state continues for a predetermined time, the main power of the entire apparatus is forcibly shut off. At this time, since the control unit 301 stores the fact that the error signal has been received in the battery backed up before the main power supply is shut off, the control unit 301 can know what caused the main power supply to be shut off. .

In this embodiment, the same effects as in the first embodiment can be obtained.

[0054]

As is apparent from the above description, according to the present invention, the means for detecting whether or not the recording material carrier is rotating, and the means for detecting the rotation of the recording material carrier, Means for stopping the power supply to the charger for applying a high voltage to the recording material carrier, regardless of the insulation distance between the charger and the recording material carrier coupling plate, the charger to the transfer sheet As a result, the charging efficiency of the charger can be improved.

Further, a high voltage power supply for supplying a high voltage to the charger has a timer circuit which is reset by an output prohibition signal from the connection detecting means or an output control signal from the device control unit, and the timer is set to a predetermined value. By stopping the high-voltage output of the high-voltage power supply unit after counting the time, even if any failure occurs and these signals are not generated normally, the device can be safely stopped or shut off. You can now let.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an electrophotographic digital color copying machine of Examples 1 and 2.

FIG. 2 is a block diagram for explaining Embodiment 1 of the present invention.

FIG. 3 is a timing chart for explaining the first embodiment in a normal state (a) and in an abnormal state (b).

FIG. 4 is a timing chart when a rotation detection signal is not output in the first embodiment.

FIG. 5 is a timing chart at the time of failure in the first embodiment.

FIG. 6 is a block diagram for explaining a second embodiment;

FIG. 7 is a diagram for explaining a positional relationship between a transfer sheet and an inner charger.

[Explanation of symbols]

 Reference Signs List 5 transfer device 5a transfer drum (recording material support) 5d inner charger 5f transfer sheet (support sheet) 5i transfer sheet connecting plate 301 control unit 302 high voltage power supply 303 rotation detection sensor 304 rotation detection flag 305 rotation detection signal generation unit 306 connection Plate detection sensor 309 Timer circuit

Claims (5)

[Claims] An image bearing member rotatably supported; an exposure device for exposing the image carrier to an image signal; a developing device for developing a toner image on the exposed latent image on the image carrier; A recording material carrier that rotates and contacts with the image carrier at the same peripheral speed and carries a recording material on which a final output image is recorded; and a transfer unit that transfers a toner image on the image carrier to the recording material. In the image forming apparatus, means for detecting whether or not the recording material carrier is rotating, and a charger for applying a high voltage to the recording material carrier in accordance with a rotation detection result of the recording material carrier. Means for stopping power supply. 2. The recording material carrier is stretched over an opening area of a peripheral surface of the recording material carrier, and is connected to a dielectric carrier sheet for carrying the recording material and both ends of the carrier sheet on the peripheral surface thereof, and is grounded. A conductor connecting plate, wherein the charger is an inner charger that is disposed inside the recording material carrier and applies a high voltage to the carrier sheet, and the inner charger and the coupling plate are at opposing positions. It has a connecting plate detecting means for detecting whether or not there is, according to a detection result by the connecting plate detecting means, when the inner charging device and the connecting plate are at opposing positions, supply power to the inner charging device. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is prohibited. 3. A high-voltage power supply for supplying a high voltage to the inner charger has a timer circuit reset by an output prohibition signal from the connection detecting means or an output control signal from a device control unit. 3. The image forming apparatus according to claim 2, wherein when the circuit finishes counting a predetermined time, the high voltage output of the high voltage power supply unit is stopped. 4. The high-voltage power supply section has means for detecting that a high voltage is being output, and the high-voltage output detection signal is being output and the recording material carrier rotation detection signal is being output at the same time. 4. The image forming apparatus according to claim 3, wherein the main power supply of the apparatus is forcibly shut off instantaneously or after a predetermined time when there is no power supply. 5. A means for detecting at least one or more recording material tip positions on the recording material carrier, and detecting that the recording material carrier is rotating based on these recording material tip position detection signals. 5. The apparatus according to claim 1, further comprising: a unit that detects a position where the connecting plate and the inner charger face each other based on the recording material front end position detection signal. 6. Image forming device.