JPH0369970A - Method for stopping actuation of electrostatic recording device - Google Patents

Abstract

PURPOSE:To solve the problem of the flow of magnetic powder carrier and the lubrica tion of a cleaning blade by disconnecting the power source of developing bias voltage impressed on a developing device after an electrostatically charged area formed on a photosensitive drum passes the part of a developing device by an electrostatic charge just before the power source is disconnected. CONSTITUTION:Just before the power source of the electrostatic charger 12 is discon nected, the power source of the developing bias voltage impressed on the developing device 16 is disconnected after the electrostatically charged area formed on the photo sensitive drum 10 by the electrostatic charger 12 passes the part of the developing device 16. Namely, until such an electrostatically charged area passes the part of the developing device 16, a potential difference between the surface potential of the photosensitive drum 10 and the developing bias voltage of the developing device 16 is made comparatively small in a state where the developing bias voltage is still impressed on the developing device 16. Thus, the magnetic powder carrier of two- component developer is kept from adhering to the photosensitive drum 10 side at the time of stopping the actuation, the cleaning blade 22 is prevented from being abraded quickly and the so called burr is stopped from occurring on the cleaning blade.

Description

[Detailed Description of the Invention] [Summary] An object of the present invention is to provide a method for stopping the operation of an electrostatic recording device using electrophotographic technology, which can solve the problem of outflow of magnetic powder carriers and the problem of lubrication of the cleaning blade. For the purpose of this, a charger applies a charge to a rotary electrostatic latent image carrier to form a charged area, an electrostatic latent image is written in the charged area, and the electrostatic latent image is developed with charged toner by a developer. A method for stopping the operation of an electrostatic recording device, in which the power to the charger is turned off, and the charged area formed on the rotary electrostatic latent image carrier by the charger passes through the developing device immediately before the power is turned off. An operation stop method characterized by turning off a developing bias voltage power source applied to a developing device.

[Industrial application field]

The present invention relates to a method for stopping the operation of an electrostatic recording device using electrophotographic technology.

[Conventional technology]

Referring to FIG. 5, a schematic structure of an electrostatic recording device using electrophotographic technology is shown, and this electrostatic recording device is provided with a photosensitive drum 10 as a rotary electrostatic latent image carrier. The photosensitive drum 10 is driven to rotate in the direction of arrow A, and chargers 12 are sequentially installed around the photosensitive drum 10 along the rotational direction.
, optical exposure means 14, developing device 16, toner transfer device 18
, a static eliminating lamp 20, and a toner cleaning blade 22 are arranged.

The charger 12 is configured, for example, as a corona discharger, and the corona discharger applies an electric charge to the photosensitive surface of the photosensitive drum 10, thereby forming a --like charged area thereon. Fifth
In the example shown in the figure, the photosensitive drum 10 is positively charged, and its potential is, for example, +460V.

An electrostatic latent image is written on the charged area formed on the photosensitive drum 10 by the charger 12 by the optical exposure means 14 . That is, when the charged area of the photosensitive drum 1o is exposed by the optical exposure means 14, the charge at that area is released and the potential is lowered to, for example, +50V,
An electrostatic latent image is formed due to the potential difference.

As the optical exposure means (4), for example, a laser beam scanning optical system, a light emitting diode array, a liquid crystal shutter array, etc. are used.

The electrostatic latent image written by the optical exposure means 14 is developed into a visible image by a developing device 16 using charged toner.

The developing device 16 includes, for example, a holding container 16a that holds developer, and a developing roll 16b that transports the developer in this holding container 16a to the photosensitive drum IO side. In the example shown in FIG. 5, a two-component developer consisting of a magnetic powder carrier and colored resin powder, so-called toner, is used as the developer, and these magnetic powder carrier and toner are stored in the holding container 16a.
They are stirred inside and triboelectrically charged to opposite polarities. For example, the magnetic powder carrier is negatively charged and the toner is positively charged. A magnet is built into the developing roll 16b, and when the developing roll 16b is rotated in the direction of arrow B, a so-called magnetic brush is formed around the developing roll 16b, and the toner is carried along with the magnetic brush and transferred to the photosensitive drum 10 side. will be transported to. The toner conveyed by the developing roll 16b is attached only to the electrostatic latent image area, but at this time, a developing bias is applied to the developing roll 16b so that the magnetic powder carrier (negative) is not electrostatically attracted to the photosensitive drum 10 side. A voltage, for example, +240 V is applied.This point will be explained in detail below with reference to FIG.

In FIG. 6, the surface potential distribution of the photosensitive drum 10 with respect to the OV level is shown by a solid line, and the surface potential distribution of the developing roll 16b is shown by a broken line. As shown in FIG.
The surface potential of 0 is +4 except for the electrostatic latent image area (+50V)
60V, and the magnetic powder carrier (indicated by e) and toner (indicated by ■) are located at the +240V level. The positive toner is transferred to the photosensitive drum 1 by the developing roll 16b.
6, the negative magnetic powder carrier adheres to the electrostatic latent image area (so-called charge well) so as to supplement the positive charge.At this time, the negative magnetic powder carrier
The electrostatic attraction force is exerted on the magnetic powder carrier by the magnet in the image formation roller 16b because the potential difference between the photosensitive drum 10 and the developing roll 16b is relatively small. Since the magnetic attraction force exerted on the photosensitive drum lo exceeds the electrostatic attraction force, the magnetic powder carrier does not adhere to the photosensitive drum lo side. In short, toner adheres only to the electrostatic latent image area of the photosensitive drum 10, and the electrostatic latent image is developed as a visible image.

When such a developed toner image reaches the toner transfer device 18 due to the rotation of the photosensitive drum 10, a recording medium such as recording paper is introduced between the photosensitive drum 10 and the toner transfer device 18. Like the charger 12, the toner transfer device 18 is also configured as a corona discharger, and this toner charger gives the recording paper an electric charge with a polarity opposite to that of the developed toner image.
The formed toner image is transferred from the photosensitive drum 10 to the recording paper side by electrostatic attraction. Note that the recording paper carrying the transferred toner image is sent to, for example, a heat fixing device (not shown), where the transferred toner image is thermally melted and fixed to the recording paper.

On the other hand, the area where the developed toner image has been transferred from the photosensitive drum 10 to the recording paper is entirely illuminated by the charge removal lamp 20, and as a result, residual charges are removed from the area. The area from which the residual charge has been removed is then wiped by a cleaning blade 22 to remove residual toner, paper dust, etc. therefrom.

The area cleaned by the cleaning blade 22 is charged again by the charger 12 and is prepared for writing of an electrostatic latent image by the optical exposure means 14. Note that the cleaning blade 22 is formed from a suitable bottom rubber material.

[Problem to be solved by the invention]

When stopping the recording operation of the electrostatic recording device as described above, conventionally, the power source of the rotation drive motor of the photosensitive drum 10, the power source of the charger 12, the power source of the rotation drive motor of the developing roll 16b, and the power source of the rotation drive motor of the developing roll 16b are used. Since the development bias voltage power supplies of the two are turned off at the same time, magnetic powder carriers adhere to the photosensitive surface of the photosensitive drum 10, resulting in various troublesome problems.

To explain this point in detail, since the charging region is continuously formed on the photosensitive drum 10 by the charger 12, the power source of the charger 12 and the developing bias voltage power source of the developing roll 16b are turned off at the same time. When, photosensitive drum 1
The relationship between the surface potential of 0 and the surface potential of the developing roll 16b is as shown in FIG. That is, while the surface potential of the photosensitive drum 10 is +460V, the surface potential of the developing roll 16b is OV, and the magnetic powder carrier and toner are positioned at the OV level.

Therefore, the surface potential of the photosensitive drum 10 and the developing roll 16b
Since the potential difference between the surface potential of As a result, the electrostatic attraction force that attracts the negative magnetic powder carrier toward the photosensitive drum 10 exceeds the magnetic attraction force exerted on the magnetic powder carrier by the magnet in the developing roll 16b. It will adhere to the photosensitive drum 10 as shown in the figure.

The magnetic powder carrier is a metal powder such as magnetite coated with a suitable resin, and its particle size is larger than that of the toner. Therefore, if such magnetic powder carriers adhere to the photosensitive surface of the photosensitive drum IO and are caught by the cleaning blade 22, not only will the cleaning blade be worn out faster, but the photosensitive surface of the photosensitive drum 10 will also be damaged. Become. Further, in some cases, the cleaning blade 22 may be curled due to the magnetic powder carrier, and in this case, the operation of the electrostatic recording device is temporarily stopped and the cleaning blade 22 is turned over.
This will involve troublesome work such as replacing the parts. Particularly, when the electrostatic recording device is configured as a high-speed printer, the problem of abrasion of the cleaning blade 22 is even more severe, and the problem of adhesion of the magnetic powder carrier to the photosensitive drum 10 must be solved.

Furthermore, the problem that the magnetic powder carrier flows out of the developing device 16 each time the electrostatic recording device is stopped cannot be ignored. This is because, in the case of two-component toners, the mixing ratio of magnetic powder carrier and toner must be maintained within a certain range in order to obtain a certain developed toner concentration, and is usually dependent on toner consumption. However, if the magnetic powder carrier flows out, not only the toner but also the magnetic powder carrier must be replenished.

By the way, in the conventional electrostatic recording device as described above, after the area where the developed toner image has been transferred from the photosensitive drum 10 to the recording paper is neutralized by the static eliminating lamp 20, residual toner is removed from the static neutralizing area by the cleaning blade 22. Although it has already been mentioned that the residual toner is removed by the toner, what should be noted here is that the residual toner plays a role as a lubricant for smoothly wiping and engaging the cleaning blade 22 with the photosensitive surface of the photosensitive drum 10. That's what it means. However, the area where the residual toner exists is limited only to the writing area of the electrostatic latent image, and in particular, the residual toner does not exist at both end areas of the photosensitive drum 10. As a result, so-called curling development may occur at both ends of the cleaning blade 22.
In this case, as described above, troublesome work such as replacing the cleaning blade 22 is required.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for stopping the operation of an electrostatic recording device using electrophotographic technology, which can solve the above-mentioned problem of outflow of magnetic powder carriers and lubrication of the cleaning blade. It is to be.

[Means to solve the problem]

According to the present invention, a charger applies a charge to a rotary electrostatic latent image carrier to form a charged area, an electrostatic latent image is written in the charged area, and the electrostatic latent image is charged by a developer. When stopping the operation of an electrostatic recording device that develops with toner,
First, the power to the charger is turned off, and the charged area formed on the rotary electrostatic latent image carrier by the charger immediately before the power is turned off passes through the developing device and is then applied to the developing device. The developed bias voltage power is turned off.

[For production]

As is clear from the above configuration, in the operation stop method according to the present invention, the charged area formed on the rotary electrostatic latent image carrier by the charger immediately before turning off the power to the charger touches the developing device. After passing, the developing bias voltage power applied to the developing device is turned off. That is,
Until the charged area passes through the developing device, the developing bias voltage is applied to the developing device, and the surface potential of the rotary electrostatic latent image carrier and the developing bias voltage of the developing device are The potential difference is made relatively small. Therefore, adhesion of magnetic powder carriers to the charged areas of the rotary electrostatic latent image carrier is prevented. On the other hand, after the above-mentioned charged area passes through the toner development area, the rotary electrostatic latent image member comes into contact with the developing device in its uncharged area, and the developing bias applied to the developing device at this time Voltage power is turned off. Therefore, just before the developing bias voltage power is turned off, the potential of the uncharged area of the photosensitive drum is substantially OV, while the potential of the developing device is +240V, so there is no charge on the uncharged area side. A small amount of toner will migrate from the toner developer and adhere throughout, and this toner will act as a lubricant for the cleaning blade when the next recording operation begins.

〔Example〕

Next, an embodiment of the method for stopping the operation of an electrostatic recording apparatus according to the present invention will be described with reference to FIGS. 1 to 4 of the accompanying drawings.

FIG. 1 shows an electrostatic recording apparatus configured to implement the recording operation stop method according to the present invention, together with a control block diagram thereof. Since the individual components of the electrostatic recording device shown in FIG. 1 are similar to those shown in FIG.
The same reference numerals and symbols as in FIG. 5 are used in the figure, and the functions of each component are as described in FIG. 5.

That is, the recording operation of the electrostatic recording apparatus shown in FIG. 1 is the same as that described with reference to FIG.

In FIG. 1, reference symbols M+ and M2 indicate drive motors for the photosensitive drum 10 and the developing roll 16b, respectively, and pulse motors or the like are used as these drive motors M+ and M2, respectively.

In FIG. 1, reference numeral 24 indicates a control circuit, and it goes without saying that this control circuit 24 not only stops the recording operation of the electrostatic recording device according to the present invention, but also controls the recording operation itself. The control circuit 24 sends drive signals to the drive motors M+ and M2 during the recording operation, thereby driving the photosensitive drum 10 and the developing roll 16b to rotate. Note that the control circuit 24 is configured by, for example, a microcomputer.

Further, in FIG. 1, reference numeral 26 indicates a high voltage power source, and a predetermined voltage is applied to the charger 12 by this high voltage power source 26. Specifically, when the charger 12 is configured as a corona discharger, a corona voltage VC and a grid voltage V are applied to the corona discharger. As is well known, the potential of the charged area of the photosensitive drum 10 can be appropriately set by adjusting the grid voltage V9. In this embodiment, immediately after the charged area is formed on the photosensitive drum IO, the grid voltage V is adjusted so that the potential thereof becomes, for example, +600V. By the time it reaches , the potential drops to about +460V due to inevitable discharge. On the other hand, the high voltage power supply 26 is connected to the developing roll 16b of the developing device 16.
A developing bias voltage V is also applied to the developing bias voltage Vd, for example, +240V. Application of voltage to the charger 12 and the developing roll 16b is controlled by a signal output from the control circuit 24 to the high voltage power supply 26. That is, when an ON signal is output from the control circuit 24 to the high voltage power supply 26, the charger 12 or the developing roll 1
A predetermined voltage is applied to 6b, and when an off signal is output from the control circuit 24 to the high voltage power supply 26, the voltage applied to the charger 12 or the developing roll 16b is cut off.

When the recording operation of an electrostatic recording device is stopped according to the present invention, the manner in which the recording operation is stopped depends on whether the electrostatic recording device is for high speed or low speed.

This is because in high-speed electrostatic recording devices, even if the rotation of the photosensitive drum is stopped, the photosensitive drum continues to rotate over an angle of 180° or more due to its inertia, whereas in low-speed electrostatic recording devices, the photosensitive drum continues to rotate over an angle of 180° or more due to its inertia. This is because in an electrostatic recording device, when the rotational drive of the photosensitive drum is stopped, the rotational movement is immediately stopped.

Referring to the recording operation stop routine shown in FIG. 2A and the recording operation stop time chart shown in FIG. 2B, first,
A method of stopping recording operation when the electrostatic recording device is for high speed will be explained. The recording operation stop routine shown in FIG. 2A is executed after toner transfer to the final page of recording paper is completed.

In step 201, a charger off signal is output from the control circuit 24 to the high voltage power supply 26, whereby both the corona voltage VC and the grid voltage V applied to the charger 12 are turned off. Next, in step 202, the output of the drive signal to the drive motor M1 is stopped, but at this time, the photosensitive drum 10 does not immediately stop its rotational movement as described above, but instead continues its rotational movement due to inertial force up to the angular range. continue.

As is clear from the time chart in FIG. 2B, the output of the charger off signal from the high voltage power supply 26.\ and the stop of the output of the drive signal to the drive motor M are performed substantially simultaneously, and the time It is represented by T1.

When the output of the drive signal to the drive motor M1 is stopped in step 202, in step 203, for example, the control circuit 24
The timer function is activated to determine whether time T has elapsed. When the time T has elapsed, the process proceeds to step 204, where the control circuit 24 outputs a developing bias voltage off signal to the high voltage power supply 26, which causes the developing roll 16b to
The developing bias voltage V, which had been applied to the image forming apparatus, is turned off. Next, in step 205, the output of the drive signal to the drive motor M2 is stopped, thereby stopping the rotation of the developing roll 16b. As is clear from the time chart in FIG. 2B, the output of the developing bias voltage off signal to the high voltage power supply 26 and the stop of the output of the drive signal to the drive motor M2 are performed substantially simultaneously, and the time point is T2. It is shown.

For the time 1'15'r (T2-'r,), for example, from the time when the output of the drive signal to the drive motor M1 is stopped, the photosensitive drum 10 moves by an angle θ due to its inertia as shown in FIG. Therefore, the charged area formed on the photosensitive drum 10 by the charger 12 just before the charger off signal is output to the high voltage power supply 26 passes through the developing roll 16b of the developer 16. The state will be as follows. On the other hand, since the developing bias voltage to the developing roll 16b is kept at the applied value until the time T has elapsed, the magnetic powder carrier is not moved from the developing roll 16b side to the charged area of the photosensitive drum 10. There isn't. The last charged area formed on the photosensitive drum 10 is the developing roll 1.
6b, the developing roll 16b comes into contact with the uncharged area of the photosensitive drum 10, and at this time, as shown in FIG. 3, the surface potential of the photosensitive drum IO is set to OV, while the developing roll 16b Since a developing bias voltage of +240V is applied, the toner is transferred to the developing roll 1.
It moves from the 6b side to the non-charged area side of the photosensitive drum 10 and is attached thereto. Such toner will function as a lubricant for the cleaning blade when the next recording operation starts.

Next, referring to the recording operation stop routine shown in FIG. 4A and the recording operation stop time chart shown in FIG. 4B,
A method for starting and stopping recording when the electrostatic recording device is for low speed will be explained. Note that the recording operation stop routine shown in FIG. 4A is executed after toner transfer to the final page of recording paper is completed, as in the case of FIG. 2A.

In step 401, a charger off signal is output from the control circuit 24 to the high voltage power supply 26, thereby causing the corona voltage VC and grid voltage V9 applied to the charger 12 to
are cut together. As is clear from the time chart in FIG. 4B, the output of the charger off signal to the high voltage power supply 26 is expressed at time T1.

In step 402, for example, a timer function within the control circuit 24 operates to determine whether or not time T has elapsed. When the time T has elapsed, the process proceeds to step 403, where the output of the drive signal to the drive motor MI is stopped, and at this time the photosensitive drum 10 stops its rotational movement. As is clear from the time chart in FIG. 4B, the time point at which the output of the drive signal to the drive motor M1 is stopped is represented by T2.

For example, the time T (T2-T,) is selected as the time during which the photosensitive drum 10 is rotated by an angle θ as shown in FIG. Therefore, immediately before the charger off signal is output to the high-voltage power supply 26, the charger 12
The charged area formed at zero is the developing roll 16 of the developing device 16.
It will be in the state where it has passed the point b. On the other hand, until the time T has elapsed, the developing bias voltage applied to the developing roll 16b is kept low, so the magnetic powder carrier is not moved from the developing roll 16b side to the charged area of the photosensitive drum 10. . When the last charged area formed on the photosensitive drum IO passes the developing roll 16b, the developing roll 16b comes into contact with an uncharged area of the photosensitive drum IO. As a result, as in the case of a high-speed electrostatic recording device, the toner moves from the developing roll 16b side to the non-charged area side of the photosensitive drum 10 and is deposited there.

When the time T has elapsed, the process proceeds to step 404, where the control circuit 24 outputs a developing bias voltage off signal to the high voltage power supply 2.
6, thereby cutting off the developing bias voltage V applied to the developing roll 16b. Next, in step 405, the output of the drive signal to the drive motor M2 is stopped, thereby stopping the rotation of the developing roll 16b. As is clear from the time chart in FIG. 2B, the output of the drive signal to the drive motor Ml is stopped, the developing bias voltage off signal is output to the high voltage power supply 26, and the drive signal is output to the drive motor M2. The stopping occurs substantially simultaneously.

In the above embodiments, the case where the magnetic powder carrier is negatively charged and the toner is positively charged in a two-component developer has been described, but the same applies to a two-component developer such as ζ whose charging polarity is reversed. I can say that. In that case,
The charged area of the photosensitive drum is formed by negative charges, and the developing bias voltage is also negative.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, when the electrostatic recording device stops operating, the magnetic powder carrier of the two-component developer is prevented from adhering to the photosensitive drum, so that the cleaning blade can be immediately activated. Abrasion can be prevented. Furthermore, since toner that functions as a lubricant for the cleaning blade can be attached to the photosensitive drum, so-called blistering of the cleaning blade can be prevented at the start of the next recording operation.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an electrostatic recording device configured to implement the recording operation stop method according to the present invention together with its control block diagram, and FIG. 2A is a schematic diagram showing the electrostatic recording device of FIG. FIG. 2B shows the recording operation stop routine when
A time chart when the recording operation of the electrostatic recording device is stopped according to the recording operation stop routine shown in FIG. Diagrammatically shown figure, Figure 4A
1 is a recording operation stop routine when the electrostatic recording device is for low speed use, and FIG. 4B is a time chart when the recording operation of the electrostatic recording device is stopped according to the recording operation stop routine of FIG. 4A. , FIG. 5 is a diagram showing a schematic structure of an electrostatic recording device, and is a diagram explaining a conventional recording operation stop method, and FIG. 6 is a diagram illustrating the potential state of a photosensitive drum and a developing roll during toner development. FIG. 7 is a diagram schematically showing the potential state of the photosensitive drum and the developing roll when the electrostatic recording apparatus is stopped according to the conventional recording operation stopping method. DESCRIPTION OF SYMBOLS 10... Photosensitive drum, 14... Optical exposure means, 16a... Holding container, 18... Toner transfer device, 22... Cleaning blade, 26... High voltage power supply, ? vL 2M2... Drive motor. 12... Charger, 16... Developing device, 16b... Developing roll, 20... Static elimination lamp, 24... Control circuit,

Claims (1)

[Claims] 1. A rotary electrostatic latent image carrier (1) is charged by a charger (12).
0) A method for stopping the operation of an electrostatic recording device in which a charged area is formed by applying an electric charge to the charged area, an electrostatic latent image is written in the charged area, and the electrostatic latent image is developed with charged toner by a developing device (16). The power to the charger (12) is turned off, and the charged area formed on the rotary electrostatic latent image carrier (10) by the charger (12) immediately before the power is turned off is transferred to the developing device. An operation stop method characterized by turning off the developing bias voltage power applied to the developing device (16) after passing the point (16).