JPH11237814A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily detect the mounting condition of a photoreceptor when the processing device of an image forming device is combined with units. SOLUTION: In this device constituted by combining the processing device of the image forming device with a developing unit 10 and a photoreceptor unit 20, a voltage controlling device 30 is arranged for a transfer roller 26, and the voltage of a given value is applied to the transfer roller 26 in the initial operation of the device, and a control circuit 31 detects the presence or absence and abnormality of the attachment of a photoreceptor in accordance with the information of the change of the voltage detected by a voltage drop detecting circuit 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus in which a unit provided with a photosensitive drum is detachably mounted on an apparatus main body, and more particularly to a photosensitive drum using a current detecting means provided in a transfer means. The present invention relates to a device capable of detecting a mounting state of a device.

[0002]

2. Description of the Related Art Generally, in an electrophotographic image forming apparatus, a charger for uniformly charging the surface of a photoreceptor,
There are provided means for irradiating the photosensitive member with light of an image to form an electrostatic latent image and developing means for developing the electrostatic latent image on the photosensitive member as a toner image. Then, the toner image on the photoreceptor is transferred onto a sheet as a recording medium by a transfer unit, and the sheet carrying the toner image is fixed through a fixing device, so that the sheet is discharged as a recording sheet. In the image forming apparatus, a power supply unit for applying a voltage of a predetermined value to a charger and a transfer unit for uniformly charging the photosensitive drum, and a predetermined unit for a component of the developing device. Power supply means for applying a voltage and charging the toner are disposed.

In an image forming apparatus such as a general copying machine or a printer, in a relatively large-sized apparatus, members such as a photosensitive drum and a developing device are individually attached to a process device mounting portion of a copying machine main body. It is configured to be attachable, so that each component can be separately attached and detached. On the other hand, in a small-sized image forming apparatus, the process device is configured as one unit, or the photosensitive drum and the developing device are configured as separate units, and each unit is configured to be detachable from the apparatus main body. Some are doing. When the process device is configured as one unit, the unit is replaced according to the life of the photosensitive drum.
The replacement work of the unit can be easily performed.

In the case where the photosensitive drum unit and the developing device unit are separately constructed, the two components of the photosensitive drum and the developing device having different lifespans are combined. Even if the apparatus is configured, each unit can be replaced according to the life of each component, and the feature that each component can be used effectively can be exhibited. As described above, by configuring each component of the process apparatus to be replaceable, maintenance of the apparatus such as a printer can be easily performed.

[0005]

However, in the case where each component of the process apparatus is configured to be replaceable, a copy cannot be created unless each unit and the like are securely set at a predetermined position. In addition, sensors for detecting the mounting state of each unit are arranged at predetermined positions. However, arranging sensors for detecting each mounting state in correspondence with the number of units to be mounted in combination requires, in addition to increasing the number of sensors, processing signals from the sensors. It is necessary to provide a circuit in the control device, which greatly affects the manufacturing cost of the image forming apparatus. In addition, there is a problem that arranging extra wires and the like in the apparatus greatly affects maintenance of the image forming apparatus.

The present invention solves the above-mentioned problem of the conventional unit detecting means, and indirectly detects the mounting state of the unit via a power supply for applying a voltage to the transfer means of the process apparatus. It is intended to provide a device for obtaining.

[0007]

SUMMARY OF THE INVENTION The present invention provides a photoreceptor, a transfer unit for transferring a toner image on the photoreceptor to a recording medium,
An image forming apparatus comprising: a power supply unit that applies a voltage to the transfer unit; a detection unit that detects a current flowing into the transfer unit; and a voltage control unit that controls a voltage of the power supply unit based on the current detected by the detection unit. Related to the device. The invention according to claim 1 of the present invention is characterized in that a judging means for judging the presence or absence of the photoconductor is provided based on the current detected by the detecting means. According to a second aspect of the present invention, the apparatus further comprises a second determination unit that determines an abnormality of the power supply unit based on the current detected by the detection unit. The invention of claim 3 is
The transfer unit is a conductive roller that rotates while contacting the photoconductor.

In the present invention, the use of the provision of a means for monitoring the voltage flowing into the transfer means for controlling the degree of transfer of the toner image in the image forming apparatus is utilized. Can be easily determined. Further, since it is not necessary to provide a sensor, a signal circuit, and a judging means for detecting the mounting state of the unit, the manufacturing cost of the apparatus can be reduced, and the configuration of the apparatus can be simplified. .

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the apparatus of the present invention will be described with reference to the illustrated example. FIG. 1 shows an example in which a process unit arranged in an image forming unit of an image forming apparatus is configured by combining a developing unit 10 and a photoconductor unit 20. The configuration and operation will be described later. In the process device, the photosensitive drum 2 provided in the photosensitive unit
1, after the charging roller 22 performs uniform charging, irradiates light from a writing device 25 composed of an LED to form an electrostatic latent image, and develops the electrostatic latent image. The toner is supplied from the roller 14 and is visualized as a toner image. The toner image formed on the photosensitive drum 21 is transferred to the sheet by applying a predetermined potential from the back surface of the sheet at the transfer position corresponding to the transfer roller 26 by the transfer roller. After the toner image is transferred onto the paper, the toner remaining on the photosensitive drum is further dispersed by the charging roller in a state where the toner is disturbed by the memory removing brush 23 and the adhesive force is weakened. Will be collected.

In the above-described process apparatus, when a voltage is applied to the transfer roller to transfer a toner image onto a sheet, there is a problem that the transfer degree is not constant only by applying a constant voltage due to environmental conditions or the like. In order to control the degree of transfer of the toner image, a change in the voltage at the transfer roller is monitored, and means for controlling the voltage applied to the transfer roller in accordance with the change in the voltage value is provided. As means for controlling the voltage, a voltage control device 30 as shown in FIG. The voltage control device 30 includes a high-voltage power supply 34 for applying a voltage to the transfer roller, a voltage drop detection circuit 32 for detecting a change in current flowing into the transfer roller, and a current detected by the voltage drop detection circuit. It is configured in combination with a control circuit 31 that controls the voltage applied from the high-voltage power supply based on the value.

In the voltage control device 30, the voltage information detected by the voltage drop detection circuit 32 is transmitted to the control circuit 31.
To read the control data corresponding to the voltage information with reference to the table 33a in the memory 33, and apply the set control voltage from the high voltage power supply 34 based on the read control information. The voltage control device 30 controls the operation of transferring a toner image formed on the photosensitive drum onto a sheet by applying a predetermined voltage to the transfer roller 26. In the state where the transfer is not performed, the voltage control device 30 is not operated.

On the other hand, in the present invention, the operation of detecting the mounting of the photoreceptor unit is performed using the voltage control device 30. When the power supply of the image forming apparatus is turned on, the voltage control is performed. The apparatus 30 is operated to transfer the transfer roller 2
6 is performed. When the voltage is applied at the beginning of the operation, the conditions for applying the voltage in the initial stage are set in the control table 33a connected to the control circuit. , High voltage power supply 3
A voltage having a predetermined value from 4 is applied. By performing the operation of applying the voltage, when the photoconductor unit is normally mounted, the data detected by the voltage drop detection circuit 32 is in a normal value range. It is displayed that it is correctly equipped.

In the initial operation of the voltage control device,
If the photoconductor unit is not properly mounted, the voltage drop detecting circuit 3
The voltage detected at 2 is lower than the reference voltage. Further, when an abnormality occurs in the photosensitive drum, a value larger than the reference voltage is obtained because the load resistance is reduced. Therefore, in the control circuit of the voltage control device,
The value detected by the voltage drop detection circuit 33 is compared with data in a table 33a in the memory 33 to determine whether the device is abnormal or normal and to display the same on the display unit 35, which is transmitted to the operator. it can. Therefore, by applying a voltage of a constant value to the transfer roller initially and making a determination based on the detection result of the voltage drop detection circuit, whether or not the photosensitive drum is mounted, an abnormal state of the photosensitive drum, Alternatively, the abnormality of the power supply means can be easily determined, and this state is displayed via the display unit.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The overall structure of an image forming apparatus to which the present invention can be applied will be described below with reference to FIGS. The image forming apparatus 1 provided with the detecting means to which the present invention is applied is configured to feed a sheet by mounting a sheet feeding cassette 2 at a lower portion of the main body. The paper feed cassette 2 is provided with a bottom plate 2a on which paper is placed and a separation claw 2b for separating paper. Further, a pickup roller 3 is provided for feeding paper from a paper feed cassette, and a half-moon roller is used as the roller 3.
Conveying roller devices 4 and 5 are disposed in a sheet conveying path for guiding the sheet fed from the sheet feeding cassette, and a fixing device 28 is provided downstream of an image transfer section by a transfer roller 26, and a discharge roller device 29 is provided. And a path for discharging the copy via the. The roller device 5 applies a voltage from the transfer roller 26 while feeding the paper in time with the toner image formed on the photoconductive drum 21, so that the toner image formed on the photoconductive drum 21 is applied to the paper. It is configured to transfer.

In the image forming apparatus shown in this embodiment,
A side plate 7 of the apparatus main body is provided to be openable and closable in the middle of the paper transport path from the paper feed cassette 2, and when a paper jam or the like occurs in the paper transport path, a guide plate provided integrally with the side plate is provided. Used when performing jam clearance when opened. Also, the side plate 7
A manual feed tray 6 is provided through an opening provided in an upper part of the paper feeder. A manual feed roller 8 is arranged corresponding to the paper feed path, and another paper feed system for feeding paper toward the transport roller device 5 is provided. Is composed. Further, sensors S1, S2 and the like for detecting the paper are arranged in the paper transport path, and the transport of the paper in the paper transport path is controlled using the detection information of the sensors.

In the main body of the image forming apparatus, a process unit disposed above the frame is constituted by combining a developing unit 10 and a photosensitive unit 20. The two units 10 and 20 constituting the process unit are provided so that the upper lid member 9 provided at the upper part of the apparatus main body can be taken out upward with the open state via the fulcrum 9a. The upper cover member 9 is provided with an image writing device 25 for writing an image on the photosensitive drum, and when the upper cover member 9 is closed, writing of the image writing device on the photosensitive drum 21 is performed. Automatically set to position.

A developing unit 10 provided in the process unit includes a stirrer 12 for stirring the toner in a toner container 11 containing the one-component toner, a developing roller 14 disposed corresponding to the photosensitive drum, and A supply roller 13 for supplying the toner to the developing roller 14 while charging the toner, and a blade 15 for forming the toner adhered to the surface of the developing roller 14 as a thin layer are arranged. The supply roller 13 and the developing roller 14 are driven in the same direction while being pressed against each other, so that the toner is charged by friction between the two rollers so that the toner adheres to the surface of the developing roller. . The toner adhering to the surface of the developing roller 14 is
5 is pressed to form a thin layer having a constant thickness, and is exposed toward the developing position with respect to the photosensitive drum 21.

The photosensitive unit 20 combined with the developing unit includes a photosensitive drum 21 and a charging roller 22 for uniformly charging the photosensitive drum. Reference numeral 21 is connected to the ground of the body frame and is grounded. Further, a memory removing brush 23 is provided below the frame of the photoconductor unit 20 so as to disturb the toner remaining on the photoconductor drum and reduce the adhesion of the toner.

In the process unit having the above-described structure, the supply roller 13 provided on the developing unit 10 is provided with a sponge-like conductive elastic body or a flocked body having conductive fibers having a predetermined thickness. It can be configured as an elastic roller provided as described above. The shaft of the supply roller 13 is provided with a power supply member (not shown)
A bias voltage having a value of about 500 to -700 V, preferably about -600 V is applied. Further, the developing roller 14
Is made of a metal roller shaft made of stainless steel or the like coated with conductive rubber (silicone rubber, urethane rubber, NBR) with a predetermined thickness, and has a smooth roller surface. A bias voltage having a value of about -200 to -400 V, preferably about -300 V is applied to the developing roller 14. The blade 15 disposed on the developing roller 14 is
This is for uniformly setting a thin layer of toner formed on the surface of the device, and has a spring property made of a urethane resin sheet or a stainless steel plate member. And, for the blade 15, -300V to -500
A bias voltage in a range of V, preferably around -400 V is applied.

The distance between the axes of the supply roller 13 and the developing roller 14 is set to be slightly smaller than the sum of the radii of the two rollers, and by rotating both rollers in the same direction (the direction of arrow X). At the contact portion between the two rollers, the roller is slid in the opposite direction while being pressed. Then, the toner is charged between the two rollers by the frictional action of the two rollers and the difference between the voltages applied to the respective rollers, and the toner adheres to the surface of the developing roller 14. Further, the toner adhered to the surface of the developing roller 14 is formed to a uniform thickness by the blade 15 and is exposed to the photosensitive drum, and the toner is transferred to a latent image formed on the photosensitive drum to transfer the toner. Form an image.

The photosensitive unit 20 arranged in combination with the developing unit 10 includes a photosensitive drum 21 and a photosensitive drum 21.
A charging roller 22 such as a brush roller whose surface is formed by a flocked member or the like is provided. Then, an image writing device 25 is arranged on the photosensitive drum 21 to write an image, and the toner image formed on the photosensitive drum is transferred to a sheet by a transfer roller. The image writing device 25 includes an LED head array, and emits light to irradiate the photosensitive drum with light based on information from an image information output device.
The surface of the photoreceptor drum 21 is made of a grounded photoconductor, charged at -750 V by the charging roller 22, and irradiated with light from the image writing device 25, that is, a portion of the image information corresponding to black. Is -80
V, and a potential difference occurs between the light-irradiated part and the non-irradiated part (the part corresponding to white in the image information), and an electrostatic latent image corresponding to the image information is formed.

With respect to the electrostatic latent image formed on the photosensitive drum, approximately -68 is attached to the surface of the developing roller 14.
When the toner charged to 0 V comes into contact with the toner, the toner is attracted to the light irradiation site on the surface of the photoconductor drum 21 and a toner image is formed on the surface of the photoconductor drum 21 (reversal development). At the transfer position of the toner image, a bias voltage of 800 to 2 kV is applied from the back surface of the sheet by a transfer roller, so that the toner image is transferred to the sheet. The sheet on which the toner image has been transferred is sent to the fixing device 28 by the rotation of the photosensitive drum. Further, after the toner image is transferred onto the paper, the toner remaining on the surface of the photosensitive drum is disturbed by the charging roller 22 and dispersed on the surface of the photosensitive drum, and the toner on the surface of the photosensitive drum is charged. Is charged to the same potential as. Then, at a position where the photosensitive drum contacts the developing roller 14, the photosensitive drum is transferred to the developing roller 14 due to a potential difference between the two, and is mixed with the toner newly supplied from the container and reused.

In the apparatus shown in FIGS.
In order to detect the mounting state of the photoconductor unit of the process unit and the abnormality of the apparatus, a voltage control device as shown in FIG. 1 can be provided to detect the mounting state of the photoconductor drum. Further, when the two units are combined to form a process device, for example, the process unit of the image forming apparatus body may be mounted in a state where the two units are combined, or the photoconductor unit may be mounted after the developing unit is mounted. In any of the cases where the photoconductor unit is mounted, it can be easily detected whether or not the photoconductor unit is normally mounted.

[0024]

Since the apparatus of the present invention is constructed as described above, a means for monitoring the voltage flowing into the transfer means is provided in order to control the degree of transfer of the toner image in the image forming apparatus. By utilizing this fact, it is possible to easily determine the presence or absence of a unit including a photoreceptor by using the means. In addition, since it is not necessary to provide a sensor, a signal circuit, and a determination unit for detecting the mounting state of the unit, the manufacturing cost of the apparatus can be reduced.
It is possible to simplify the configuration of the device. Further, in the present invention, a voltage of a constant value is initially applied to the transfer roller, and a determination is made based on a detection result by a voltage drop detection circuit to determine whether or not the photosensitive drum is mounted, An abnormal state of the drum, an abnormality of the power supply means, and the like can be easily determined, and a normal operation of the apparatus can be assured by displaying the abnormality through the display unit.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of a control device of the present invention.

FIG. 2 is an explanatory diagram of an image forming apparatus to which the control device of FIG. 1 can be applied;

FIG. 3 is an explanatory diagram of a process device arranged in the image forming apparatus of FIG. 2;

[Explanation of symbols]

1 image forming apparatus, 2 paper cassette, 3
Pickup roller, 8 paper feed roller, 10 developing unit, 11 toner container, 12 stirrer, 13 supply roller, 14 developing roller, 2
0 photoconductor unit, 21 photoconductor drum, 2
2 Charging brush, 23 Memory removal brush, 25
Writing device, 26 transfer roller, 28 fixing device, 29 discharge roller device, 30 voltage control device, 31 control circuit, 32 voltage drop detection circuit, 33 memory, 34 high voltage power supply, 35
Display section.

Claims (3)

[Claims] A photoconductor, transfer means for transferring a toner image on the photoconductor to a recording medium, power supply means for applying a voltage to the transfer means, detection means for detecting a current flowing into the transfer means, An image forming apparatus comprising: a voltage control unit that controls a voltage of a power supply unit based on a current detected by a detection unit, wherein the determination unit determines presence or absence of a photoconductor based on the current detected by the detection unit An image forming apparatus comprising: 2. The image forming apparatus according to claim 1, further comprising a second determination unit that determines an abnormality of the power supply unit based on the current detected by the detection unit. 3. The image forming apparatus according to claim 1, wherein the transfer unit is a conductive roller that rotates while being in contact with a photosensitive member.