JPH0454955B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is directed to cleaning the surface of a toner image forming body of an electrostatic recording device such as an electronic copying machine or an electrostatic printer, and cleaning the surface of the toner image forming body. The present invention relates to controlling the amount of recovered toner returned when the toner is returned to a toner replenisher for a developing device and reused.

[Prior art]

In electrostatic recording devices such as so-called electronic copying machines or electrostatic printers, an electrostatic latent image is formed on the surface of a photoconductive photoreceptor, for example, and this is developed into a toner image, which is then transferred to a transfer material such as paper. A recorded matter is obtained by transferring the toner onto the toner image forming body, but a portion of the toner remains on the toner image forming body even after the transfer. The remaining toner is removed by a cleaning device in preparation for reusing the toner image forming body.
be captured. In order to save on consumption, the collected toner is returned to a developing device or a toner replenishing device from a cleaning device using a toner conveying device for reuse. However, once the toner is used, its performance deteriorates and foreign matter such as paper dust may be mixed in. Therefore, if the amount of recovered toner in the developer exceeds a certain limit, the quality of the recorded images may deteriorate significantly. I have a problem to say. Therefore, in order to maintain the performance of the developer, it is necessary to appropriately control the amount of recovered toner returned to the developer or toner replenisher, and to replenish new toner with unused toner. Excess collected toner is stored in a collection container and disposed of.

Japanese Patent Application Laid-open No. 122472/1983 discloses a device for conveying recovered toner collected in a cleaning device to a developer and a recovery container by arbitrarily switching between them for the above-mentioned purpose. There is no mention of controlling the amount of reduction to .

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for controlling a reducing device in an electrostatic recording device that reuses collected toner, which can obtain high-quality recording without deterioration in image quality caused by reusing collected toner. be.

[Structure of the invention]

The purpose of the above is to provide a conveyance screw that operates and conveys the toner collected in the cleaning section into a toner recovery container in conjunction with the rotation of the toner image carrier, and a branch in the middle of the conveyance screw to transfer the toner to a developing device or a developing device. A toner reducing device is provided with a conveyance path for returning toner to a toner replenisher that replenishes toner, and an electromagnetically operated valve that controls the amount of toner returned by opening and closing the valve.
The valve is configured to reduce or stop the ratio of the operating amount of the toner reducing device to the operating amount of the toner image carrier when the number of continuously recorded sheets is less than or equal to a predetermined number than when the number exceeds a predetermined number. This has been achieved by a method of controlling a toner reducing device in an electrostatic recording device, which is characterized by controlling the operation of the toner reducing device.

[Function and effect of the invention]

In an electrostatic recording device such as a so-called electronic copying machine, the photosensitive drum usually rotates once at the start of recording, and then passes through charging, exposure, development, transfer, and cleaning to obtain the first recorded item. .
If continuous recording of n sheets is set in advance, the steps from charging onward are repeated n times to obtain n recorded objects. When recording of the n-th sheet is completed, the photosensitive drum rotates one more time and then stops. The first rotation is to irradiate the entire surface of the photoconductor drum with light to stabilize the state of optical fatigue on the photoconductor, and the last rotation is to erase the afterimage on the photoconductor and perform cleaning. Since no image is created, no toner is consumed, but some recovered toner that adheres to the drum from the developing device and is collected by the cleaning device is generated and returned to the developing device. On the other hand, in the process of image formation, although some collected toner is generated, most of the toner is transferred to paper and consumed.

The toner concentration in the developer is detected by means such as measuring the reflectance of the toner image formed on the photosensitive drum by a reference reflector, and is automatically replenished with unused toner as needed to keep it constant. controlled. Therefore, if the above-mentioned generation and reduction of recovered toner without consumption of toner is repeated, the ratio of recovered toner in the developer increases unilaterally, and the image quality of the obtained copies sharply deteriorates.

As mentioned above, for continuous recording of n sheets, the drum always rotates twice without toner consumption, and the ratio is 2/n, so the amount of recovered toner tends to increase as the number of sheets continuously recorded decreases. growing. Most simply, when n = 1, i.e., when the task of making one copy per original is repeated, the photosensitive drum repeats idling - copying - idling - stop each time, and the idling, which does not consume toner and only generates collected toner, produces an image. This means that the forming operation will be twice as long as the forming operation, resulting in a noticeable deterioration in image quality.

The method of the present invention reduces the ratio of the operating amount of the collected toner reducing device that transports the collected toner from the cleaning device to the developing device or the toner replenishing device to the operating amount of the toner image carrier when the above-mentioned n is less than a predetermined number of sheets. , or by stopping it, the return of recovered toner to the developing device is reduced or stopped, thereby suppressing an increase in the amount of recovered toner in the developer, and saving toner while suppressing deterioration in developer performance. It is something that we try to do. In other words, the above-mentioned toner return device normally operates during the period when the recording operation is performed and the toner image carrier is working, and returns all collected collected toner to the developing device. is less than a predetermined number, the operating time of the collected toner reducing device is shortened or the operating speed is reduced, and the ratio of the operating amount to the operating amount of the toner image carrier is reduced or controlled to be stopped. By doing so, we aim to achieve our goals. The collected toner may be controlled in conjunction with a program for specifying the number of continuous recording sheets in the electrostatic recording apparatus main body.

The above predetermined number of continuous recording sheets depends on the usage conditions of the electrostatic recording device, that is, the ratio of continuous recording to decimal recording,
The number of sheets varies depending on the size of frequently used paper, the properties of the developer, etc., so it must be determined experimentally depending on each practical condition, but 3 to 10 sheets is usually appropriate.

〔Example〕

FIG. 1 shows an example of an electrostatic copying machine suitable for carrying out the method of the present invention, and the figure shows an outline of its cleaning section and recovered toner reduction device.

Toner remaining on the photosensitive drum 1, which is a toner image body, even after the transfer process is scraped off by a cleaning blade 2 and collected at the bottom of a cleaning device 3. The collected toner is discharged from the cleaning device by the screw 4, conveyed by the conveyance screws 5 and 6, and returned to the developing device 7. However, an electromagnetically actuated valve is installed at a branch point from the conveyance screw. 8 is provided, and when the valve 8 is closed, the collected toner is further conveyed and stored in a toner collection container 9. Replenishment of unused toner to the developing device is performed through a replenishment port 10.

A control program is configured such that the copy number setting circuit of the copying machine and the valve 8 are linked to close the valve 8 when the set number of copies is less than a predetermined number n, and to open the valve 8 when the set number is n or more. As mentioned above, the value of n is determined experimentally according to practical conditions, but in most cases n=5 to 5 in tests using the above prototype machine (manufactured by Konishiroku Photo Industry Co., Ltd.).
Good results were obtained by setting it to 6.

The above embodiment is for the case where the return of toner to the developing device is stopped when the number of continuously recorded sheets is below a predetermined number, but depending on the usage conditions, for example, when the number of continuously recorded sheets is below a specified number, toner return Of course, a control method such as opening the valve 8 for 1/2 of the device operating time and closing the valve 8 for 1/2 of the operating time may also be used, and more favorable results can often be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a cleaning section and a recovered toner reducing device of an electrostatic copying machine suitable for carrying out the present invention. 3...Cleaning device, 4...Recovered toner discharge screw, 5, 6...Recovered toner conveying screw, 7...Developer, 8...Valve, 9...Toner recovery container.

Claims (1)

[Scope of Claims] 1. A conveying screw that operates and conveys the toner collected in the cleaning section into a toner collecting container as the toner image bearing member rotates, and a developing device or developing device that branches off in the middle of the conveying screw. The toner reducing device is equipped with a conveyance path for returning toner to a toner replenisher that replenishes toner to a container, and an electromagnetically operated valve that controls the amount of toner returned by opening and closing the valve. Therefore, when the number of continuously recorded sheets is less than a predetermined number, the ratio of the operating amount of the toner reducing device to the operating amount of the toner image carrier is lowered or stopped, compared to when the number of continuously recorded sheets is less than a predetermined number, compared to when it exceeds a predetermined number. A method for controlling a toner reducing device in an electrostatic recording device, the method comprising controlling the operation of the valve.