JP2983112B2 - Electrophotographic recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic recording apparatus for recording an image by an electrophotographic process.

[0002]

2. Description of the Related Art In an electrophotographic recording apparatus, the surface (photosensitive surface) of a photoreceptor is charged at a predetermined potential (for example, -600) by a charging device.
After being charged to V), an exposure is performed according to an image to be recorded by an exposure device to form an electrostatic latent image on a photosensitive surface of a photosensitive member. Then, development is performed by applying toner to the photosensitive surface of the photoconductor in accordance with the formed electrostatic latent image by a developing device.

The developing device carries a toner on a developing roller, transports the toner, and brings the toner into contact with the surface of the photoreceptor. When the toner carried on the developing roller is transported, the toner is thinned by a developing blade arranged in contact with the developing roller,
It is triboelectrically charged to the same polarity (negative polarity) as the charging potential of the photoconductor. A developing bias having the same polarity as the charged potential of the photoconductor and a low voltage (for example, -200 V) is applied to the developing roller, and the toner is selectively adhered to the photoconductor by the action of the electrostatic latent image and the developing bias. Let it. That is, the toner is not attached to the unexposed portion on the photoconductor because the photoconductor side has a high potential for the toner, and the photoconductor side is low potential for the toner on the exposed and destaticized portion. Toner adheres. Thus, a toner image corresponding to the electrostatic latent image is formed on the surface of the photoconductor. Then, the toner image is transferred to the recording paper by the transfer device.

[0004] In such an electrophotographic recording apparatus,
Since a recording paper jam may occur on the recording paper transport path, the occurrence of the jam is detected, and the recording operation is stopped when the jam occurs.

The detection of a jam is performed by, for example, recognizing the occurrence of a jam when a recording paper sensor provided in a recording paper transport path has been ON for a predetermined time or more.

For this reason, the occurrence of a jam cannot be recognized until a predetermined time elapses after the recording paper sensor is turned on, and the apparatus continues to operate for a while after the occurrence of the jam. As described above, since toner adheres to the photoconductor until the operation of the apparatus stops after the occurrence of the jam, if the transfer device has a transfer roller that comes into contact with the photoconductor, as described above, The toner attached to the body
The toner adheres to the transfer roller until the operation of the apparatus is stopped or when the operation is restarted.

Immediately after toner replenishment or replacement of a developing device (for example, integrated with a process unit together with a photoconductor and a charging device), the amount of toner stored in the developing device is reduced. Because the pressure is large, the toner easily slips between the developing roller and the developing blade due to the pressure, so that insufficiently charged toner comes into contact with the photoconductor. Since the development is performed by the action of the electric field as described above, the above operation is not performed properly if the charge amount of the toner does not reach a specified value, and the toner adheres even if the photosensitive drum is uniformly charged. As a result, this adheres to the transfer roller.

If the toner adheres to the transfer roller as described above, there is a problem that the back surface of the recording paper is stained at the time of subsequent recording, or the transfer efficiency is reduced to cause a transfer failure.

[0009]

As described above, in the conventional electrophotographic recording apparatus, toner adheres to the transfer roller when a jam occurs, when toner is supplied, or when a developing device (process unit) is replaced. This causes problems such as contamination of the back surface of the recording paper and a decrease in transfer efficiency.

The present invention has been made in view of such circumstances, and an object of the present invention is to prevent contamination of the back surface of a recording sheet by toner adhered to a transfer roller and a reduction in transfer efficiency. An object of the present invention is to provide an electrophotographic recording device capable of performing the above-mentioned steps.

[0011]

In order to achieve the above object, according to the present invention, a detection means detects that an apparatus cover has been closed from an open state, and this detection means
Upon detecting that the device cover has been closed,
For example, a photosensitive member such as a photosensitive drum is rotated by a photosensitive member rotating unit such as a main drive system, and the photosensitive member is charged by a charging unit such as a charging device. In a state where a bias is applied to the developing roller and the rotation of the developing roller is stopped by a developing roller rotating means such as a developing resist driving system, for example, a voltage switching means such as a switch is turned at least once at a first state ( For example, a first voltage generating means such as a transfer power supply generates a state in which a first voltage such as a transfer voltage is applied to the transfer roller, and a second state (for example, a second voltage generating means such as a roller cleaning power supply generates). For example, a second voltage such as a roller cleaning voltage is applied to the transfer roller.

[0012]

By taking such measures, when the apparatus cover is closed from the open state, after that, with the photoconductor uniformly charged, the positive voltage and the negative voltage are applied to the transfer roller. Are applied alternately. Therefore, when a positive voltage is applied to the transfer roller, the positively charged toner adhering to the transfer roller is repelled from the transfer roller, and when a negative voltage is applied to the transfer roller. Then, the negatively charged toner adhering to the transfer roller is repelled from the transfer roller and moves to the photoconductor side.

[0013]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a partially cutaway view showing the entire configuration of a facsimile apparatus to which the electrophotographic recording apparatus according to the present embodiment is applied. The facsimile apparatus has a process unit A, an exposure device B, a transfer device C, a fixing device D, a paper feed mechanism E, a registration roller F, and a transmission mechanism G.

The process unit A integrally comprises a photosensitive drum 1, a charger 2, a developing device 3 and a cleaning device 4, and forms a toner image on the photosensitive drum 1 together with the exposure device B by a so-called Carlson process. It has become something. The process unit A is provided detachably with respect to the apparatus main body.

Exposure apparatus B includes an LED head,
Exposure of the photosensitive drum 1 is performed to form an electrostatic latent image on the photosensitive drum 1. The transfer unit C transfers the toner image formed on the photosensitive drum 1 to a recording sheet supplied from a sheet cassette (not shown) by the sheet feeding mechanism unit E. The fixing device D fixes the toner image transferred to the recording paper. The registration roller F corrects (aligns) the skew of the recording paper transported by the paper feeding mechanism E, and transports the recording paper between the photosensitive drum 1 and the transfer device C (transfer position). The transmission mechanism G is a part that optically reads a transmission original and performs photoelectric conversion to generate an image signal.

FIG. 2 is a diagram showing the configuration of the process unit A, the exposure apparatus B, and the developing apparatus C, and the functional block configuration of the electric system related thereto. The same parts as those in FIG. 1 are denoted by the same reference numerals.

The photosensitive drum 1 has a photosensitive layer formed by applying a photosensitive conductive material on the surface. Around the photosensitive drum 1, a charger 2, an exposure device B, a developing device 3, a transfer device C, and a cleaning device 4 are arranged along the peripheral surface of the photosensitive drum 1. The process unit A is formed by integrally configuring the photosensitive drum 1, the charger 2, the developing device 3, and the cleaning device 4 by a side cover (not shown). The charger 2 includes, for example, a well-known scorotron charger, and applies a predetermined potential (for example, −600) to the surface of the photosensitive drum 1.
V) is uniformly charged.

The developing device 3 includes a toner hopper 31, a toner pack 32, a supply roller 33, a developing roller 34, a developing blade 35, a support rod 36, a leaf spring 37, a support 38, and a reinforcing plate 39.

The toner hopper 31 is a hollow container having a part of a side surface and an open top surface, and stores toner (not shown) in a toner storage space 31a indicated by a broken line. A toner pack 32 is mounted on an upper opening of the toner hopper 31. The toner pack 32 is a container having an opening on one side. The inside of the toner pack 32 is filled with toner, and the opening is sealed by a seal (not shown). When the toner pack 32 is attached to the toner hopper 31 as shown in FIG. By doing so, toner can be supplied to the toner hopper 31.

The supply roller 33 is disposed at an opening on a side surface of the toner hopper 31 with a part thereof positioned inside the toner hopper 31. The supply roller 33 is in contact with the developing roller 34, carries the toner stored in the toner hopper 31, and conveys and supplies the toner to the developing roller 34 by rotating. The developing roller 34 is in contact with the photosensitive drum 1 and the toner hopper 3
The toner supplied from the toner carrier 1 is carried, and is conveyed by being rotated and brought into contact with the surface of the photosensitive drum 1.

The developing blade 35 is made of silicon resin or urethane, and keeps the amount (toner layer thickness) of the toner carried and conveyed by the developing roller 34 constant and also frictionally charges the toner. The developing blade 35 is provided on a cylindrical support rod 36 and is in contact with the developing roller 34. The support rod 36 is pressed against the developing roller 34 by a predetermined force (for example, 50 g / cm ²⁾ by a leaf spring 37 fixed to a support 38. ~ 100g / cm ² ), And the developing blade 35 is pressed against the developing roller 34 by the above-mentioned force. The support 38 is the toner hopper 31
Is fixed to the side wall.

The reinforcing plate 39 is fixed to the support 38 and a side cover (not shown) of the process unit A, so that the rigidity of the process unit A is increased and the toner carried by the developing roller 34 is scattered. To prevent On the other hand, the cleaning device 4 includes a cleaning blade 41, a waste toner container 42, a waste toner roller 43, and a check valve 44.

The cleaning blade 41 is disposed in contact with the photosensitive drum 1 and scrapes off toner adhered to the photosensitive drum 1. The waste toner accommodating section 42 stores the toner (waste toner) scraped off by the cleaning blade 41.
Collect. The waste toner roller 43 conveys the toner scraped off by the cleaning blade 41 to the waste toner container 42 side. The backflow prevention valve 44 prevents the toner in the waste toner container 42 from flowing back to the photosensitive drum 1 side. The transfer device C includes a transfer roller 51, a transfer power supply 52, a roller cleaning power supply 53, and a switch 54. The transfer roller 51 is in contact with the photosensitive drum 1, and the recording paper P is inserted between the transfer roller 51 and the photosensitive drum 1.

The transfer power supply 52 is for applying a transfer voltage of a predetermined voltage value (for example, +1350 V) having a polarity (positive polarity) opposite to the charge potential of the toner to the transfer roller 51. The roller cleaning power supply 53 has a polarity (negative polarity) opposite to the transfer voltage and a predetermined voltage value (for example, -1000 V).
Is applied to the transfer roller 51. The voltage generated by each of the transfer power supply 52 and the roller cleaning power supply 53
4 is applied to the transfer roller 51. The switch 54 can also turn off the voltage application to the transfer roller 51 without selecting either the transfer power supply 52 or the roller cleaning power supply 53.

Reference numeral 6 denotes a developing bias power supply having the same polarity as the charging potential of the photosensitive drum 1 and a low voltage (for example, -200 V).
Generates a large developing bias. The developing bias power source 6 is electrically connected to a developing roller 34 via a switch 7. A supply bias power supply 8 generates a supply bias having a predetermined voltage value (for example, -300 V). The supply bias power supply 8 is electrically connected to the supply roller 33 via the switch 9.

Reference numeral 10 denotes a main drive system. The main drive system 10 includes, for example, a motor and a gear, and rotates the photosensitive drum 1 and the transfer roller 51 in directions indicated by arrows. Reference numeral 11 denotes a developing resist driving system.
The development resist drive system 11 includes, for example, a motor and a gear, and rotates the supply roller 33, the development roller 43, and the registration roller F in directions indicated by arrows. Reference numeral 12 denotes a control unit, which performs overall control of each unit.

Reference numeral 13 denotes a cover opening / closing sensor which detects an opening / closing operation of an apparatus cover (not shown). In the facsimile apparatus of the present embodiment, a part of the housing is used as a device cover that can be opened and closed for maintenance.
Detects the state of the device cover. Specifically, for example, it is configured by a switch that is turned on / off by a part of the device cover. Next, the operation of the electrophotographic recording apparatus in the facsimile apparatus configured as described above will be described according to the control procedure of the control unit 12.

First, in the standby state, the control unit 12 operates the main drive system 10 (rotation of the photosensitive drum 1 and the transfer roller 51), the charging operation of the charging device 2, the exposure operation of the exposure device B, and the developing resist driving system 11 Operation (supply roller 3
3, the rotation of the developing roller 34 and the registration roller F) are all stopped. The switches 7, 9, and 54 are all turned off.

In this standby state, when a process start signal is given from a control device (not shown) which controls the entire facsimile machine, the operation of the main drive system 10 is started in synchronization with the process start signal, and the photosensitive drum 1 and the transfer are transferred. At the same time as the rotation of the roller 51 is started, the charging device 2 starts the charging operation (time T1 in FIG. 3). At the time T1, the control unit 12 turns on the switch 54 to the roller cleaning power supply 53 side. As a result, a negative roller cleaning voltage generated by the roller cleaning power supply 53 is applied to the transfer roller 51.

Subsequently, the control unit 12 switches the switch 54 to the transfer power supply 52 side when a predetermined time TA has elapsed from the time T1 (time T2 in FIG. 3). Where time TA
Indicates that a certain position on the surface of the photosensitive drum 1 is
There is a slight margin in the time required to move from a contact position between the photosensitive drum 1 and the transfer roller 51 (hereinafter referred to as a transfer position) from a contact position between the photosensitive drum 1 and the transfer roller 51 (hereinafter referred to as a transfer position). , For example, 1.
59 seconds. The reason that the roller cleaning voltage is applied to the transfer roller 51 over the time TA is that the toner on the area of the surface of the photosensitive drum 1 which is located between the developing position and the transferring position in the standby state is set. This is because the toner is repelled by a roller cleaning voltage having the same polarity as the charged polarity of the toner until this area passes, thereby preventing the toner from adhering to the transfer roller 51.

Subsequently, at a point in time when a predetermined time TB has elapsed from the point in time T1 (point in time T3 in FIG. 3), the switches 6 and 8 are turned on to apply the developing bias to the developing roller 34 and supply the developing roller. The application of the supply bias to 33 starts. Here, the predetermined time TB is set at 1 for the photosensitive drum 1.
The sum of the time required for rotation and the time required for a certain position on the surface of the photosensitive drum 1 to move from a position where the photosensitive drum 1 faces the charging device (hereinafter, referred to as a charging position) to a developing position. (For example, 4.81 seconds) as the minimum value. The reason why the time from the start of charging to the start of application of the developing bias to the developing roller 34 is delayed over the time TB is that the surface of the photosensitive drum 1 is stably charged over the entire circumference. After that, the developing device 3 is operated.

After a short time TC (for example, 0.5 seconds) from the time T3, the control unit 12 starts the operation of the developing resist driving system 11 to rotate the supply roller 33, the developing roller 34, and the resist roller F. (Fig. 3
T4 in the middle). Thereafter, the control unit 12 sets the predetermined period TD
, The supply roller 33, the developing roller 34 and the registration roller F are rotated. Here, the predetermined time TD is set to, for example, 3 seconds or more, with the time required for the developing roller 34 to make one rotation as a minimum value. The period extending to the time TD is a warm-up period of the developing device 3,
In particular, it aims at stably charging the toner carried on the developing roller 34. Control unit 1
2 is to stop the operation of the development resist drive system 11 at the time when the time TD has elapsed from the time T4,
The rotation of the developing roller 34 and the registration roller F is stopped (time T5 in FIG. 3). By the above operation, the preparation of each unit is completed, and the image recording operation can be performed.

In this state, when a print start signal is given from a control unit (not shown) which controls the entire facsimile apparatus (at time T6 in FIG. 3), the control unit 12 waits for a short time, and then the exposure unit B is caused to start the exposure operation (at time T7 in FIG. 3). Further, the control unit 12 starts the operation of the developing resist driving system 11 at a time when a predetermined time TE has elapsed from the time T6,
4 and the rotation of the registration roller F are started (time T8 in FIG. 3). Here, the predetermined time TE is: TE = (time required for the recording paper P to move from the registration sensor to the registration roller) + (registration amount time) −
(Time from registration sensor ON to arrival of print start signal) Determined by the following equation. Although not shown, the registration sensor is provided in the vicinity of the registration roller F, and detects that the recording paper P has reached the registration roller F. The registration amount time is a time required from when the recording paper P first strikes the registration roller F to when alignment is completed.

In the present embodiment, the distance from the registration roller F to the transfer position in the transport path of the recording paper P is set longer than the distance from the development position to the transfer position on the movement locus of the surface of the photosensitive drum 1. A registration roller F is provided.

At the transfer position, the photosensitive drum 1
The leading edge of the upper toner image and the leading edge of the recording paper P must be substantially aligned. In this embodiment, as described above, the recording paper P
Is longer than the distance from the developing position to the transfer position in the movement trajectory of the surface of the photosensitive drum 1 in the transport path of the photosensitive drum 1, so that the rotation of the resist roller F The start is earlier than the end of the electrostatic latent image reaches the developing position. Therefore, when the electrostatic latent image reaches the developing position and the developing operation is to be started in the developing device 3, since the aligning has already been completed, the developing resist drive system 11 is stopped and the resist roller F There is no need to stop the rotation, so that the rotation of the developing roller 34 does not stop during the developing operation.

Thus, hereinafter, the recording operation is performed as follows. That is, first, the surface (photosensitive surface) of the photosensitive drum 1 is charged to a predetermined potential (for example, −600 V) by the charging device 2, and then exposed according to the image to be recorded by the exposure device B, and the electrostatic latent image is formed. Is formed. Then, the developing device 3 develops the electrostatic latent image formed on the photosensitive surface of the photosensitive drum 1.

The developing device 3 carries the toner mainly supplied by the supply roller 33 from the toner hopper 31 on the developing roller 34, transports the toner, and contacts the surface of the photosensitive drum 1. When the toner carried on the developing roller 34 is conveyed, the toner is thinned by the developing blade 35,
The photosensitive drum 1 is frictionally charged to the same polarity (negative polarity) as the charged potential.

Since a developing bias (for example, -200 V) is applied to the developing roller 34 from the developing bias power source 6, the toner is selectively adhered to the photosensitive drum 1 by the action of the electrostatic latent image and the developing bias. . That is, the toner is not attached to the unexposed portion on the photosensitive drum 1 because the photosensitive drum 1 is at a high potential, and the toner is exposed to the exposed and destaticized portion because the photosensitive drum 1 is at a low potential. Adheres. Thus, a toner image corresponding to the electrostatic latent image is formed on the surface of the photosensitive drum 1. Then, the toner image is transferred to the recording paper P by the transfer device C.

In the transfer device C, a positive transfer voltage (for example, +1350 V) is applied to the transfer roller 51.
Charge injection is performed on the back surface of the recording paper P. Here, since the electric charge injected into the back surface of the recording paper P is positive, the negatively charged toner is attracted to the recording paper P side, whereby the toner image formed on the surface of the photosensitive drum 1 is removed. The image is transferred to the recording paper P. Thereafter, the toner remaining on the photosensitive surface of the photosensitive drum 1 without being transferred is removed by the cleaning device 4 after the recording paper P is peeled off.

The control unit 12 stops the operation of the developing resist drive system 11 and stops the rotation of the supply roller 33, the developing roller 34, and the resist roller F at the time when a predetermined time TF has elapsed from the time T8 (FIG. T3 in 3). Here, the predetermined time TF is PS for the recording paper length, f for the distance from the registration roller F to the transfer position on the transport path of the recording paper P, and f for the distance from the development position to the transfer position on the movement locus of the surface of the photosensitive drum 1. l, and recording paper P
If the transport speed of is represented by v, it is determined by, for example, ((PS + f-1) /v+1.0). Specifically, when the recording paper size is A4 size, for example, 11.73 seconds, and when the recording paper size is B4, for example, 13.15 seconds. Thereafter, when it is necessary to record the next page, the control unit 12 controls each unit at the same timing as described above in synchronization with the print start signal.

At the end of recording of the last page in one recording operation, the control unit 12 sets a predetermined time TG from the end of the exposure operation of the image (time T10 in FIG. 3).
At the point in time when elapses, the operation of the development resist drive system 11 is stopped to stop the rotation of the supply roller 33, the development roller 34, and the registration roller F (time T11 in FIG. 3). Here, the predetermined time TG is arbitrarily set with the minimum time required for the developing roller 34 to make one rotation (for example, 2.4 seconds).

Further, the control unit 12 switches the switch 54 to the roller cleaning power supply 53 side when the predetermined time TH has elapsed from the time T11, and switches the voltage applied to the transfer roller 51 to the negative roller cleaning voltage (FIG. 9). T3 in 3). Here, the predetermined time TH is T at which the rotation of the developing roller 34 of the photosensitive drum 1 is stopped.
The portion that was located at the development position at time 11 is set to be shorter than the time required to reach the transfer position.

Thus, of the surface of the photosensitive drum 1,
When the portion that has passed the developing position after the rotation of the developing roller 34 has stopped passing the transfer position, the transfer roller 5
1, a roller cleaning voltage of negative polarity is applied. The portion of the surface of the photosensitive drum 1 that has passed the developing position after the rotation of the developing roller 34 has stopped is rubbed with the toner that has adhered to the developing roller 34, so that toner adhesion occurs due to mechanical force. This toner is a normally charged toner and is charged to a negative polarity. Therefore, when passing through the transfer position, the toner is repelled by the roller cleaning voltage and is prevented from adhering to the transfer roller.

The control unit 12 stops the operation of the main drive system 10 to stop the rotation of the photosensitive drum 1 and the transfer roller 51 and the charging of the charging device 2 at the time when a predetermined time TI has elapsed from the time T12. The operation is stopped (at time T13 in FIG. 3). At the same time, the control unit 1
2 turns off the switches 7, 9, and 54,
The application of the supply bias to the transfer roller 3, the application of the development bias to the development roller 34, and the application of the voltage to the transfer roller 51 are stopped. This returns to the standby state.

By the way, the control unit 12 switches the switch 54 to the transfer power supply 52 side at the time T2,
The switch 54 is fixed to the transfer power supply 52 side until the time T12, that is, until the recording operation of all pages in one recording operation is completed.

Thus, the positively charged toner adheres (foggs) to the photosensitive drum 1 after toner replenishment or at high temperature and high humidity. However, a positive transfer voltage is always applied to the transfer roller 51. Therefore, toner adhered to the photosensitive drum 1 repelled by the transfer voltage is prevented from attaching to the transfer roller 51.

The normal sequence relating to the normal recording has been described above. However, the control unit 12 performs transfer roller cleaning different from the normal sequence according to the fact that the apparatus cover (not shown) is closed from the open state. Execute the sequence.

Hereinafter, the transfer roller cleaning sequence will be described. First, when the cover opening / closing sensor 13 detects that the apparatus cover (not shown) has been closed from the open state, the control unit 12 starts the operation of the main drive system 10 in response to the detection, and starts the operation of the photosensitive drum 1 and The rotation of the transfer roller 51 is started, and the charging device 2 is started to perform a charging operation (at time T21 in FIG. 4). Control unit 1
2 turns on the switches 6 and 8 when a predetermined time TB has elapsed from the time T21 (time T22 in FIG. 4),
The application of the developing bias to the developing roller 34 and the application of the supply bias to the supply roller 33 are started.

Thereafter, the controller 12 sets the time from the time T21 to the time when the predetermined time TJ has elapsed (time T23 in FIG. 4).
The rotation of the photosensitive drum 1 and the transfer roller 51 by the main drive system 10, the charging operation by the charging device 2, the developing roller 3
4 and the supply bias to the supply roller 33 are continuously performed. During this period, the control unit 12 controls the development resist drive system 11
Is not operated, and the rotations of the supply roller 33, the developing roller 34, and the registration roller F are stopped.

During the period of the predetermined time TJ in the above state, the control unit 12 repeatedly switches the switch 54 between the transfer power supply 52 and the roller cleaning power supply 53 at a cycle of the predetermined time TK. Here, the predetermined time TK
Is set arbitrarily with the time required for the transfer roller 51 to make one rotation as a minimum value.

The apparatus cover is openable and closable for maintenance of the apparatus.
In this case, the jam removal work, the toner supply work to the toner hopper 3 (the work of loading a new toner pack 32), or the work of replacing the process unit A are performed. A large amount of toner adheres to the photosensitive drum 1 before and after the occurrence of a jam, toner replenishment, or replacement of the process unit A, whereby toner adheres to the transfer roller 51. At this time, the charging polarity of the toner adhering to the transfer roller 51 is indefinite, and a toner charged to a negative polarity and a toner charged to a positive polarity are mixed.

However, after the apparatus cover is closed, that is, after the above operations are completed, the transfer roller cleaning sequence as described above is executed, and the transfer roller 51 is charged to the transfer roller 51 while the surface of the photosensitive drum 1 is uniformly charged. A positive transfer voltage and a negative roller cleaning voltage are alternately applied. Therefore, when a positive transfer voltage is applied to the transfer roller 51, the positively charged toner is repelled and returned to the surface of the photosensitive drum 1. When a negative roller cleaning voltage is applied to the transfer roller 51, the negatively charged toner is repelled and returned to the surface of the photosensitive drum 1. Thereby, the transfer roller 5
1 is performed, and when performing a normal recording operation thereafter, contamination of the back surface of the recording paper P is prevented.

In this embodiment, one cycle TK of applying the transfer voltage or the roller cleaning voltage is set longer than the time required for the transfer roller 51 to make one rotation, so that the entire circumference of the developing roller 51 is set. The toner can be removed over a wide range. The time TJ during which the transfer roller cleaning sequence is executed is arbitrarily set to a time (for example, about 30 to 60 seconds) sufficient to sufficiently clean the transfer roller 51.

The above is the transfer roller cleaning sequence, but the control unit 12 executes another initial sequence at the time of start-up from the operation stop state for a long time, that is, at the time of releasing the night mode, for example. The night mode is a mode in which the power of the electrophotographic recording apparatus is turned off during a time period during which communication frequency is low to reduce power consumption.

Hereinafter, the initial sequence will be described. First, when the night mode is canceled, the control unit 12 starts the operation of the main drive system 10 to start the rotation of the photosensitive drum 1 and the transfer roller 51, and
The charging device 2 starts the charging operation (at time T31 in FIG. 5). At time T31, the control unit 12 turns on the switch 54 to the roller cleaning power supply 53 side.
As a result, a negative roller cleaning voltage generated by the roller cleaning power supply 53 is applied to the transfer roller 51.

Subsequently, the control unit 12 switches the switch 54 to the transfer power supply 52 side when a predetermined time TA has elapsed from the time T31 (time T32 in FIG. 5). Further, at a point in time when a predetermined time TB has elapsed from the point in time T31 (point in time T33 in FIG. 5), the switches 6 and 8 are turned ON to apply the developing bias to the developing roller 34 and supply the developing bias to the supply roller 33. Start applying the bias. After a short time TC from the time point T33, the control unit 12 starts the operation of the developing resist drive system 11 to start the rotation of the supply roller 33, the developing roller 34, and the registration roller F (at the time point T34 in FIG. 5). ).

Thereafter, the control unit 12 sets the time when a predetermined time TL has elapsed from the time T31 (time T33 in FIG. 5).
The operation of the development resist drive system 11 is terminated, and the rotation of the supply roller 33, the development roller 34, and the registration roller F is stopped. Here, the predetermined time TL is a time required for the temperature of the heat roller incorporated in the fixing device D to reach the predetermined temperature, or a time arbitrarily set in a timer (for example, 10 to 90 seconds).

When a predetermined time TH has elapsed from the time T35, the controller 12 switches the switch 54 to the roller cleaning power supply 53 side, and switches the voltage applied to the transfer roller 51 to the negative roller cleaning voltage (FIG. 9). 5 at T36).

Further, the control unit 12 stops the operation of the main drive system 10 to stop the rotation of the photosensitive drum 1 and the transfer roller 51 and the charging device 2 The operation is stopped (at time T37 in FIG. 5). At the same time, the control unit 1
2 turns off the switches 7, 9, and 54,
The application of the supply bias to the transfer roller 3, the application of the development bias to the development roller 34, and the application of the voltage to the transfer roller 51 are stopped. Thereby, a standby state is entered.

When the operation is stopped for a long time in the night mode, the developing blade 35 always comes into contact with the same position of the developing roller 34 in the developing device 3. Since the developing blade 35 is pressed by the leaf spring 37 and presses against the surface of the developing roller 34, the position of the surface of the developing roller 34 where the developing blade 35 is in contact is distorted. If the developing operation is performed in this state, horizontal stripes are formed in the developed image portion at the distorted portion, and the image quality is reduced.

In this embodiment, however, the initial sequence is performed before the normal sequence, and the developing roller 34 is rotated to some extent. Since the developing roller 34 is mainly made of urethane or the like, it has a property of being restored to its original state by rotating, and the distortion is eliminated by the rotation in the initial sequence. Therefore, when recording is performed in the normal sequence thereafter, horizontal stripes do not occur. The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0062]

According to the present invention, the detection means detects that the apparatus cover has been closed from the open state, and in response to the detection means detecting that the apparatus cover has been closed, for example, A photosensitive member such as a photosensitive drum is rotated by a photosensitive member rotating means such as a main drive system,
For example, the photosensitive member is charged by charging means such as a charging device, and a developing switch means such as a switch is turned on by O.
In the state where a developing bias is applied to the developing roller as N and the rotation of the developing roller is stopped by a developing roller rotating means such as a developing resist drive system, for example, a voltage switching means such as a switch is turned on at least once at least once. A first state (for example, a state in which a first voltage generating means such as a transfer power supply generates, for example, a first voltage such as a transfer voltage is applied to a transfer roller) and a second state (for example, a second voltage generating means such as a roller cleaning power supply are (For example, a state in which a second voltage such as a roller cleaning voltage is applied to the transfer roller) when the positive voltage is applied to the transfer roller. When the negatively charged voltage is applied to the transfer roller, the transfer roller The negatively charged toner that is attached is repelled by the transfer roller and moves toward the photoreceptor, respectively, and the toner is removed from the transfer roller. The electrophotographic recording apparatus can prevent a decrease in efficiency and the like.

[Brief description of the drawings]

FIG. 1 is a partially cutaway view showing the entire configuration of a facsimile apparatus to which an electrophotographic recording apparatus according to one embodiment of the present invention is applied.

FIG. 2 is a diagram showing a configuration of a process unit A, an exposure apparatus B, and a developing apparatus C, and a functional block configuration of an electric system related thereto.

FIG. 3 is a timing chart showing the operation timing of each unit in a normal sequence.

FIG. 4 is a timing chart showing the operation timing of each unit in a transfer roller cleaning sequence.

FIG. 5 is a timing chart showing the operation timing of each unit in the initial sequence.

[Description of Signs] A: Process Cartridge B: Exposure Device, C
... Transfer unit, D ... Fixing device, E ...
Paper feed mechanism, F ... Registration roller,
G: transmission mechanism section, 1: photosensitive drum,
2 ... charger, 3 ... developing device, 3
DESCRIPTION OF SYMBOLS 1 ... Toner hopper, 32 ... Toner pack, 33 ... Supply roller, 34 ... Development roller, 35 ... Development blade, 36 ... Support rod, 37 ... Leaf spring, 38 ... Support body, 39 ... Reinforcement plate, 4 ... Cleaning device, 51 ... Transfer roller, 52 ...
Transfer power supply, 53 ... Roller cleaning power supply, 54 ...
Switch, 6 ... Development bias power supply, 7, 9
... switch, 8 ... supply bias power supply, 10
... Main drive system, 11 ... Development resist drive system,
12: control unit, 13: cover open / close sensor.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Hirotaka Fukuyama, Inventor 3-1-1, Asahigaoka, Hino-shi, Tokyo Inside the Toshiba Hino Plant (72) Inventor Koichiro Sato 3-1-1, Asahigaoka, Hino-shi, Tokyo Inside the Toshiba Hino Plant (72) Inventor Tetsuya Nakamura 3-1-1 Asahigaoka, Hino-shi, Tokyo Inside the Toshiba Hino Plant (72) Inventor Satoshi Katakata 3-1-1 Asahigaoka, Hino-shi, Tokyo 1 share (56) References JP-A-3-69978 (JP, A) JP-A-2-106676 (JP, A) (58) Fields investigated (Int.Cl. ⁶ , DB name) G03G 15 / 16

Claims (1)

(57) [Claims] An endless photoreceptor, a photoreceptor rotating means for rotating the photoreceptor, a charging means for charging the surface of the photoreceptor to a predetermined potential, and a charging means for charging the photoreceptor charged by the charging means. Exposure means for partially exposing the surface in accordance with an image to be recorded to form an electrostatic latent image on the surface of the photoreceptor, a developing roller for bringing the carried toner into contact with the surface of the photoreceptor, Developing roller rotating means for rotating a roller, a developing bias power supply for generating a developing bias having a predetermined voltage value to be applied to the developing roller, and developing switch means for turning on / off the application of the developing bias to the developing roller Developing means for forming a toner image corresponding to the electrostatic latent image on the surface of the photoreceptor; and a recording paper disposed so as to be in contact with the photoreceptor and nipping and transporting the recording paper together with the photoreceptor Transfer roller, first voltage generating means for generating a first voltage having a polarity opposite to the charging potential of the photoconductor to be applied to the transfer roller, and the first voltage to be applied to the transfer roller. A second voltage generating means for generating a predetermined second voltage of opposite polarity; a first state in which at least the first voltage is applied to the transfer roller; and a second state in which the second voltage is applied to the transfer roller. Transfer means for transferring the toner image formed on the surface of the photoreceptor to the recording paper; and detecting means for detecting that the apparatus cover has been closed from an open state. When the detecting means detects that the apparatus cover is closed, the photosensitive body rotating means rotates the photosensitive body, the charging means charges the photosensitive body, and the developing means switch Means is turned on, the developing bias is applied to the developing roller, and the rotation of the developing roller is stopped by the developing roller rotating means. An electrophotographic recording apparatus comprising: a control unit for setting a state.