JP2000039819A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent image flowing without shaving an image carrier nor causing cost rise because of providing a heater by removing a toner image for cleaning from the surface of the image carrier after forming the toner image for cleaning on the surface of the image carrier while rotating the image carrier in accordance with stored information in cleaning sequence. SOLUTION: A CPU 17 executes the cleaning sequence in the case of judging that there is possibility that the image flowing occurs based on the information such as the printing rate of a printed image on a photoreceptor drum 1 stored in a storage means. In order to prevent the image flowing caused by talc or the like adhering to the drum 1, toner T and the talc are mixed by forming the toner image for cleaning by developing the toner T on the drum 1 to which the talc or the like adheres for a regular interval time other than at the time of printing, and the talc and the toner T are removed together by a cleaning blade 6a in the cleaning sequence.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image forming apparatus such as a copying machine and a laser beam printer.

[0002]

2. Description of the Related Art FIG. 22 shows a schematic configuration of a conventional image forming apparatus. In the figure, M is an image forming apparatus main body which is a printer engine. Reference numeral 1 denotes a cylindrical photosensitive drum serving as an image carrier, which rotates at a predetermined process speed (peripheral speed) in the direction of arrow R1 around its axis. After the surface of the photosensitive drum 1 is uniformly charged by a charging roller 2 (rotating in the direction of arrow R2) as a charging device, an electrostatic latent image is formed by the exposure device 3. The developing device 4 includes a toner container 4a for storing and storing the toner T and a developing sleeve 4b as a toner carrier.
The toner T adheres to the electrostatic latent image formed on the photosensitive drum 1 and is developed. A developing blade 4c, which is a toner regulating member, is disposed near the developing sleeve 4b, and regulates the layer thickness of the toner carried on the surface of the developing sleeve 4b by being stirred and conveyed by the stirring member 4d. An engine control unit (not shown) having a power supply for driving the image forming apparatus and a high voltage circuit for supplying a bias for forming an image forms a direct current between the photosensitive drum 1 and the developing sleeve 4b. A developing bias in which an AC bias is superimposed on the bias is applied. The toner image on the photosensitive drum 1 visualized by the toner T is transferred to the transfer material P by the transfer roller 5 (rotated in the direction of arrow R5). The transfer material P is stored in a paper feed cassette (not shown), fed by a feed roller (not shown), and synchronized with the toner image on the photosensitive drum 1 by a transport roller 8 and a registration roller (not shown). Transfer roller 5
Sent to The toner image formed by the toner T transferred to the transfer material P by the transfer roller 5 is transported to the fixing device 9 together with the transfer material P, and is heated and pressed by the fixing roller 9a and the pressure roller 9b to be fixed on the surface of the transfer material P. Is done. The transfer material P on which the toner image has been fixed in this manner is transported by the transport rollers 10,
11. The sheet is discharged onto a sheet discharge tray 13 by a discharge roller 12. On the other hand, toner (transfer residual toner) remaining on the surface of the photosensitive drum 1 without being transferred to the transfer material P at the time of transfer is removed by the cleaning blade 11 in the cleaning device 6. The photosensitive drum 1 from which the transfer residual toner has been removed is
The next image formation is performed, and the above steps are repeated.

In the figure, reference numeral 7 denotes a photosensitive drum unit,
14 is a process cartridge, 15 is a paper ejection sensor, 16
Denotes a motor that rotates in the direction of arrow R16, and 17 denotes a CPU (control means).

When the above-mentioned image forming apparatus is a printer, image data is received from a computer to form an image. Particularly, the page printer receives image data from the computer in units of one page and performs printing. Here, the number of prints requested by the computer is called a job. For example, if a computer creates and prints a 5-page document, the job will be 5 pages. Also, when printing five copies of a one-page document, the job also includes five pages.

Conventionally, when a plurality of documents are created by a computer, it is common to create one copy of an original by a printer and copy the required number of copies by a higher-speed copying machine. . For this reason, the number of jobs is about 1 to 10.

In recent years, however, it is not uncommon for printers to generate all necessary copies of documents with the speeding up of printers. In particular, if the data transmitted by the computer is composed of only characters, the printer can print all pages almost continuously. Graphic images take time to print after converting graphic data into a printable form, resulting in intermittent printing for each page. However, characters are usually sent using character codes specified by JIS, etc. Most come. Therefore, the printer only has to print the received character code in correspondence with the built-in photo which it has in advance, and can process it in a short time. Further, CPUs capable of performing arithmetic processing at high speed have been developed, and it is expected that the number of jobs will increase more and more in the future.

In recent years, with the spread of computers, electrophotographic recording devices have been used as output devices in various countries around the world. Therefore, it is required that a high-quality image be obtained even in a high-temperature and high-humidity environment. In addition, since various kinds of transfer materials are used in various countries as a transfer material, it is desired that the transfer material can be adapted.

[0008]

However, at present,
As a problem in a high-temperature and high-humidity environment, image deletion is known. Although image deletion is also caused by condensation on the surface of the photosensitive drum, talc and the like contained in the transfer material adhere to the surface of the photosensitive drum, and an oxide formed from ozone generated by the charging device and moisture due to high humidity are combined. As a result, a low-resistance object is formed, and the low-resistance object often disturbs the electrostatic latent image to cause image deletion. Further, it may occur when a surfactant on the surface of an OHT (overhead parity) paper adheres.

As a method for solving the problem of the image deletion, a method of improving the cleaning performance of a cleaning device to remove talc adhering to the surface of the photosensitive drum or a method of disposing a heater in the photosensitive drum has been known. In addition, there is known a method in which the temperature of the photosensitive drum is raised above the ambient temperature of the photosensitive drum to lower the humidity on the surface of the photosensitive drum, thereby suppressing generation of a low-resistance substance.

However, according to the former method of improving the cleaning performance, there is a limit to the improvement of the cleaning performance, and as the cleaning performance is improved, the photosensitive drum is scraped and the durability of the cleaning device is reduced.

On the other hand, according to the latter method of disposing a heater, a new heater must be provided, which increases the cost and is not suitable for a small printer.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of preventing image deletion without shaving the image carrier, reducing the durability of the cleaning means, and increasing the cost due to the provision of the heater. It is intended for.

[0013]

According to a first aspect of the present invention, there is provided an image forming apparatus, wherein the surface of an image carrier is uniformly charged by a charging unit, and the surface of the image carrier after charging is exposed by an exposing unit. Exposing to form an electrostatic latent image, developing toner as a toner image by attaching toner to the electrostatic latent image by developing means, transferring the toner image on the image carrier surface to a transfer material by transfer means, In an image forming apparatus having a series of image forming operations in which a toner remaining on the surface of the image carrier without being transferred to the transfer material at the time of transfer is removed by a cleaning unit, information on a use state of the image forming apparatus is stored. A storage unit, a control unit that performs a cleaning sequence of the image carrier separately from the image forming operation,
The control means, in the cleaning sequence, according to the information stored in the storage means, rotates the image carrier, the developing means on the surface of the image carrier by a belt-shaped along its generatrix direction. A cleaning toner image is formed intermittently along the circumferential direction of the surface of the image carrier, and the cleaning unit removes the toner image for cleaning from the surface of the image carrier.

According to a second aspect of the present invention, in the image forming apparatus of the first aspect, the information stored in the storage means is a rotation time of the image carrier.

According to a third aspect of the present invention, in the image forming apparatus of the first aspect, the information stored in the storage means is a printing rate of a toner image formed on the transfer material. I do.

According to a fourth aspect of the present invention, in the image forming apparatus of the first aspect, the information stored in the storage means is the number of transfer materials on which images are formed.

According to a fifth aspect of the present invention, in the image forming apparatus according to the first aspect, the information stored in the storage means is a length of the transfer material on which the image is formed in a transport direction. And

The invention according to claim 6 is the invention according to claims 1, 2,
In the image forming apparatus according to any one of 3, 4, or 5, a process cartridge comprising at least one of the charging unit, the developing unit, and the cleaning unit, and the image carrier integrally incorporated in a cartridge container; An image forming apparatus main body to which a process cartridge is detachably mounted.

According to a seventh aspect of the present invention, in the image forming apparatus of the sixth aspect, the storage means is attached to the process cartridge.

According to an eighth aspect of the present invention, in the image forming apparatus of the sixth aspect, the storage means is attached to the image forming apparatus main body.

According to a ninth aspect of the present invention, the surface of the image bearing member is uniformly charged by charging means, the surface of the image bearing member after charging is exposed by exposure means to form an electrostatic latent image, and the latent image is formed by developing means. The toner is adhered to the electrostatic latent image and developed as a toner image, and a toner image on the surface of the image carrier is transferred onto a transfer material by a transfer unit, and the surface of the image carrier is not transferred to the transfer material during transfer. In an image forming apparatus having a series of image forming operations for removing toner remaining in the image carrier by a series of image forming operations, an environment detecting unit for detecting temperature and humidity, and a cleaning sequence of the image carrier separately from the image forming operations Control means for performing, in the cleaning sequence, according to a signal from the environment detection means, to rotate the image carrier,
A belt-shaped cleaning toner image is formed intermittently on the surface of the image carrier along the generatrix direction by the developing means along the circumferential direction of the surface of the image carrier. Is removed from the surface of the image carrier.

According to a tenth aspect of the present invention, in the image forming apparatus of the ninth aspect, at least one of the charging unit, the developing unit, and the cleaning unit, and the image carrier are integrally incorporated in a cartridge container. And an image forming apparatus main body to which the process cartridge is removably mounted.

According to an eleventh aspect of the present invention, in the image forming apparatus of the tenth aspect, the storage means is attached to the process cartridge.

According to a twelfth aspect of the present invention, in the image forming apparatus of the tenth aspect, the storage means is attached to the image forming apparatus main body.

According to a thirteenth aspect of the present invention, the surface of the image bearing member is uniformly charged by a charging means, and the surface of the image bearing member after the charging is exposed by an exposure means to form an electrostatic latent image. The toner is adhered to the electrostatic latent image and developed as a toner image, and a toner image on the surface of the image carrier is transferred onto a transfer material by a transfer unit, and the surface of the image carrier is not transferred to the transfer material during transfer. In an image forming apparatus having a series of image forming operations for removing toner remaining on a sheet by a cleaning unit, a sheet number detecting unit for detecting the number of transfer materials on which images are formed in one job, and the image forming operation Separately, a control unit for performing a cleaning sequence of the image carrier, the control unit, in the cleaning sequence, according to a signal from the number detection unit, The image bearing member is rotated, and the developing means forms a belt-shaped cleaning toner image on the surface of the image bearing member along the generatrix direction intermittently along the circumferential direction of the surface of the image bearing member. Means are
The cleaning toner image is removed from the surface of the image carrier.

According to a fourteenth aspect of the present invention, the surface of the image carrier is uniformly charged by charging means, the surface of the image carrier after charging is exposed by exposure means to form an electrostatic latent image, and the latent image is formed by developing means. The toner is adhered to the electrostatic latent image and developed as a toner image, and a toner image on the surface of the image carrier is transferred onto a transfer material by a transfer unit, and the surface of the image carrier is not transferred to the transfer material during transfer. In the image forming apparatus having a series of image forming operations for removing toner remaining in the cleaning unit, a length detecting unit for detecting the length of the transfer material in the transport direction, separately from the image forming operation, Control means for performing a cleaning sequence of the image carrier,
The control unit rotates the image carrier in response to a signal from the length detecting unit in the cleaning sequence, and the developing unit applies a belt-like shape along the generatrix direction to the image carrier surface. Wherein the cleaning toner image is formed intermittently along the circumferential direction of the surface of the image carrier, and the cleaning means removes the toner image for cleaning from the surface of the image carrier.

According to a fifteenth aspect of the present invention, there is provided the first or second aspect.
3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 1
In the image forming apparatus of (3) or (14), the cleaning toner image may have a charging bias of OF of the charging unit.
F, formed by the non-exposure of the exposure unit and the intermittent ON of the DC component of the developing bias of the developing unit;
It is characterized by the following.

The invention according to claim 16 is the invention according to claims 1, 2,
3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 1
In the image forming apparatus of (3) or (14), the cleaning toner image may include an intermittent ON of a DC component of a charging bias of the charging unit, no exposure of the exposure unit, and a DC component of a developing bias of the developing unit. It is formed by continuous ON.

The invention according to claim 17 is the invention according to claims 1, 2,
3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 1
In the image forming apparatus of (3) or (14), the cleaning toner image is formed by continuously turning on a DC component of a charging bias of the charging unit, intermittent exposure of the exposing unit, and a DC voltage of a developing bias of the developing unit. Continuous ON of components
Formed by

[0030]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 Referring to FIG. 1, a schematic configuration of an image forming apparatus according to the present invention is shown. In addition, FIG.
FIG. 2 is a longitudinal sectional view schematically illustrating a schematic configuration of a laser beam printer using a process cartridge.

The image forming apparatus shown in FIG. 1 includes a drum type electrophotographic photosensitive member (hereinafter, referred to as "photosensitive drum") 1 as an image carrier. FIG. 2 is a cross-sectional view illustrating an image forming apparatus using an electrophotographic method. On the surface of the photosensitive drum 1,
A charging roller (charging means) 2 is arranged in contact therewith. The charging roller 2 is driven to rotate in the direction of arrow R2 with the rotation of the photosensitive drum 1 in the direction of arrow R1, and a charging bias is applied by a charging bias application power supply (not shown).
The surface of the photosensitive drum 1 is primarily charged. Reference numeral 3 denotes an exposure device (exposure unit) for irradiating the surface of the charged photosensitive drum 1 with a laser beam to form an electrostatic latent image, and reference numeral 4 denotes a developing unit (developing unit). The developing device 4 includes a toner container 4a for storing a toner T as a developer, and a developing sleeve 4b for transporting the toner T carried on the surface to a developing position facing the surface of the photosensitive drum 1 by rotating in the direction of arrow R4. A regulating member 4c for regulating the layer thickness of the toner T carried on the surface of the developing sleeve 4b; and a stirring member 4d for stirring and transporting the toner T in the toner container 4a toward the developing sleeve 4b.

Reference numeral 5 denotes a transfer roller (transfer means) for transferring the toner image formed on the surface of the photosensitive drum 1 onto a transfer material P such as paper. The transfer roller 5 is disposed in contact with the surface of the photosensitive drum 1, and is driven to rotate in the direction of the arrow R5 as the photosensitive drum 1 rotates in the direction of the arrow R1. A transfer bias is applied to the transfer roller 5 by a transfer bias application power supply (not shown), whereby the toner image on the photosensitive drum 1 is transferred onto the transfer material P.

A cleaning device (cleaning means) 6 removes toner (transfer residual toner) remaining on the surface of the photosensitive drum 1 without being transferred onto the transfer material P during transfer.
It has a cleaning blade 6a which comes into contact with the surface of the photosensitive drum 1 and wipes off residual toner. In the image forming apparatus shown in FIG. 1, the photosensitive drum 1, the charging roller 2, and the cleaning device 6 are integrated to form a photosensitive drum unit 7. Further, the photosensitive drum unit 7 and the developing device 4 are integrated into a cartridge container 14a to constitute a process cartridge 14.
The process cartridge 14 includes an image forming apparatus main body M
It is attached detachably to the.

A fixing device 9a and a pressure roller 9b are provided on the downstream side of the transfer roller 5 in the transport direction of the transfer material P. The fixing device 9 heats and presses the transfer material P to fix a toner image on the surface. (Fixing means) 9 is provided. On the further downstream side of the fixing device 9, paper discharge rollers 10, 11, 1
2. A paper discharge tray 13 is provided.

Further, reference numeral 8 in FIG. 1 denotes a transport roller for guiding the transfer material P to a transfer nip N between the photosensitive drum 1 and the transfer roller 5, and 15 detects the transfer material P passing through the fixing device 9. A paper ejection sensor 16 is a main motor that rotates in the direction of arrow R16 to drive the photosensitive drum 1 to rotate in the direction of arrow R1. The main motor 16 is connected to the conveyance roller 8 and the fixing roller via a gear train (not shown). The roller 9a, the paper discharge rollers 10, 11, 12 and the like are also driven in conjunction with the rotation of the photosensitive drum 1. Reference numeral 17 denotes a CPU (control unit) for controlling the image forming apparatus main body M, and reference numeral 18 denotes a storage unit (to be described later in detail). In the figure, the storage unit 18 is mounted on the image forming apparatus main body M side.

Next, an image forming process of the above-described image forming apparatus will be described.

The photosensitive drum 1 is formed by coating an organic photosensitive layer (OPC) on the outer peripheral surface of a cylindrical substrate having a diameter of 30 mm.
It is driven to rotate at a peripheral speed (process speed) of 106 mm / s in one direction. The surface of the photosensitive drum 1 is applied with a charging bias in which an AC voltage (charging AC) and a DC voltage (charging DC) are superimposed on the charging roller 2 from a charging bias application power source to a predetermined polarity and a predetermined potential. Primary charging is uniform.

The surface of the photosensitive drum 1 after the primary charging is irradiated with a laser beam in accordance with image information by the exposure device 3, and the charge of the light-irradiated portion is removed to form an electrostatic latent image.

The electrostatic latent image is developed by the developing device 4. The developing sleeve 4b of the developing device 4 receives the supply of the toner T stirred by the stirring member 4d of the toner container 4a. The toner T is triboelectrically charged by rubbing with the developing blade 4c, uniformly coated on the surface of the developing sleeve 4b, and further transported to the developing position by rotating the developing sleeve 4b in the direction of arrow R4. A developing bias in which an AC voltage (developing AC) and a DC voltage (developing DC) are superimposed is applied to the developing sleeve 4b by a developing bias applying power supply (not shown). The toner adheres to the electrostatic latent image on the surface of the photosensitive drum 1 and develops the electrostatic latent image as a toner image.

The toner image on the photosensitive drum 1 is transferred to a transfer material P. The transfer material P stored in a paper feed cassette (not shown) is supplied to the transfer nip N by a paper feed roller (not shown), a transport roller 8 and the like. At this time, a transfer bias application power supply (not shown) is applied to the transfer roller 5.
A transfer bias is applied, whereby the toner image on the photosensitive drum 1 is transferred to the surface of the transfer material P.

The toner image on the transfer material P is fixed by the fixing device 9. The toner image on the transfer material P is melted and fixed on the surface of the transfer material P by the heat generated by the fixing roller 9a and the pressure applied by the pressure roller 9b. Further, at this time, while the transfer material P is passing through the fixing roller 9a, the paper discharge sensor 15 detects the transfer material P and sends a signal to the CPU 17, and the CPU 17 recognizes that the transfer material P is being fixed. When the rear end of the transfer material P passes through the fixing roller 9a, the sheet ejection sensor 1
The detection signal of 5 is cut off, and the CPU 17 recognizes that the transfer material P has been discharged. After that, the transfer material P is transferred to the discharge roller 1
The paper is discharged onto a paper discharge tray 13 above the image forming apparatus main body M by 0, 11, and 12.

On the other hand, the transfer residual toner remaining on the surface of the photosensitive drum 1 is removed by the cleaning blade 6 of the cleaning device 6.
a. When the photosensitive drum 1 from which the transfer residual toner has been removed forms an image continuously, the image forming process starting from charging by the charging roller 2 described above is repeated.

Here, a storage means 18 using a nonvolatile memory, which is one of the features of the present invention, is connected to the CPU 17 described above. The storage means 18 has a CPU 17
, The rotation time of the photosensitive drum 1, the printing rate of the printed image, the number of sheets continuously and intermittently printed on the transfer material P are stored. And CPU17
When it is determined based on the information stored in the storage unit 18 that there is a risk of image deletion, the paper ejection sensor 1
After the detection signal of No. 5 is cut off and it is determined that the image forming process is completed, the cleaning sequence which is a feature of the present invention is executed. The cleaning sequence will be described later in detail. Note that, in the present embodiment, C
The PU 17 also functions as a sheet number detecting unit.

In the embodiment, the criteria for the CPU 17 to execute the cleaning sequence are as follows.

FIG. 2 shows an image forming apparatus in which the temperature 3
Transfer material P in a high temperature and high humidity environment of 2.5 ° C and 85% relative humidity
In the case where A4 size paper is passed in the horizontal direction, the printing ratio at which image deletion starts to occur when continuous printing and single intermittent printing (hereinafter simply referred to as “intermittent printing”) are performed 1000 sheets each. And the relationship between the number of prints and the number of prints. At a printing rate of 8% or more, no image deletion occurred in both continuous printing and intermittent printing.

In the image forming apparatus, the photosensitive drum 1
In continuous printing, rotation is performed for about 3.8 seconds including inter-sheet printing per sheet, and in intermittent printing, rotation is performed for about 13.6 seconds per sheet. The reason why the rotation time of the photosensitive drum 1 in intermittent printing is long is to perform pre-rotation before printing and post-rotation after printing. The pre-rotation time is a time until the leading end of the paper reaches the photosensitive drum 1, and the post-rotation time is a time when the trailing end of the paper is separated from the photosensitive drum 1 and the paper is completely outside the image forming apparatus main body M. This is the time until the paper is discharged, and in these pre-rotation and post-rotation, the photosensitive drum 1 is rotated for a longer time than the sheet interval during continuous printing.

According to FIG. 2, it can be seen that the higher the printing ratio, the larger the number of printed sheets before the occurrence of image deletion in intermittent printing than in continuous printing. This is because, when the printing rate is high, the toner T is more developed and adhered to the photosensitive drum 1 than when the printing rate is low, and more transfer residual toner remains on the photosensitive drum 1 after the transfer. . That is, if the transfer residual toner is large, the cleaning blade 6
This is because, when the transfer residual toner is scraped off by a, the effect of scraping off ozone products and paper additives by the abrasive or the like externally added to the toner is enhanced.

The reason why the image flow is less likely to occur in the intermittent printing is that post-rotation is performed after printing. In the post-rotation, the photosensitive drum 1 is rotating, but since the primary charging is not performed for a long time, the cleaning blade 6a has a high effect of scraping off ozone products and paper additives on the surface of the photosensitive drum 1 with high efficiency. It becomes.

Therefore, according to the graph of FIG. 2, when printing is performed at a printing rate at which the average printing rate at which image deletion is likely to occur is less than 8%, the job can be continuously printed (a plurality of printings) or intermittently printed (one printing). Only prints), an equation was derived indicating the number of sheets at which each image run begins.

In the case of continuous printing: the number of image deletions A = 500 × average printing rate of continuous printing… (1) In the case of intermittent printing: the number of image deletions B = 1600 × average printing rate of intermittent printing… (2 However, the average printing rate of continuous printing and the intermittent printing rate in the above formulas (1) and (2) are the average printing rates of the continuous printing and the intermittent printing, respectively, for the total number of printed sheets.

In the present embodiment, when printing is performed in each of the continuous printing mode and the intermittent printing mode, the number of image flow occurrences, the total number of images, and the average printing rate in each printing mode are constantly updated in the storage means 18. The number of image deletions in each print mode is compared with the total number, and the cleaning sequence is executed when the total number is equal to or greater than the number of image deletions. .

Next, the cleaning sequence which is a feature of the present invention will be described in detail. Hereinafter, a case where the developing bias is turned ON / OFF will be described.

The feature of the present invention is to prevent image blur and image deletion caused by generation of a low-resistance substance caused by talc or the like adhering to the photosensitive drum 1 except during printing (image formation). The toner T is developed on the photosensitive drum 1 on which talc or the like has adhered for a certain period of time to form a cleaning toner image, the toner T and the talc are mixed, and the talc and the toner T are mixed with the cleaning blade 6a. Is to clean them together.

During the rotation of the photosensitive drum 1 other than during printing, only the DC voltage of the developing bias (DC component: hereinafter referred to as "developing DC") is turned ON at certain intervals at a certain time as shown in the sequence of FIG. (T1). During this time, the charging bias (charging AC, charging DC), exposure, and transfer bias remain OFF. Therefore, the potential on the surface of the photosensitive drum 1 during development is 0, and the development DC is turned on at regular intervals.
Since (t1), the toner T is developed on the photosensitive drum 1 at the interval. At this time, the cleaning toner image formed on the surface of the photosensitive drum 1 (hereinafter simply referred to as “toner image” as appropriate) is, as shown in FIG. It is formed intermittently (intermittently) at intervals. The length of each belt-shaped toner image is
The length is substantially the entire length of the image forming area on the surface of the photosensitive drum 1 in the axial direction. On the photosensitive drum 1, talc and toner, which are components in the paper as the transfer material P passed during printing, are adhered in a mixed state. The belt-shaped toner image developed on the photosensitive drum 1 is simultaneously cleaned with the talc by the cleaning blade 6a without being transferred to the transfer material P, and the surface of the photosensitive drum 1 is cleaned. Therefore, image blur caused by talc in images formed thereafter,
It is possible to prevent the occurrence of defective images such as image deletion.
Thereafter, a bias having the same polarity as the toner T (a minus bias in the case of the negative toner) is applied to the transfer roller 5 (FIG. 3).
Then, the transfer roller 5 is cleaned by causing the toner T attached to the transfer roller 5 to fly toward the photosensitive drum 1 (t3). After that, in order to make the surface potential of the photosensitive drum 1 uniform to 0 (zero) V, only the charging AC is applied to the photosensitive drum 1 by one.
The cleaning sequence is completed after the application of the circumference (t4).

Here, the application time t3 and the application timing of the bias applied to the transfer roller 5 are determined by turning on the developing DC.
The application may be performed in accordance with the total time t5 of the repetition of (t1) / OFF (t2) and the application timing.

The present embodiment is characterized in that a method is employed in which the application of the developing DC is repeated ON / OFF at certain intervals. This is to develop a necessary amount of toner for cleaning talc adhered to the surface of the photosensitive drum 1. The present applicant has experimented with other methods, but has the following adverse effects. For example, in the case of a method in which the absolute value of the developing DC is reduced and the toner is developed little by little while being kept ON, only the toner having an appropriate charge on the developing sleeve 4b is developed. For this reason, what is left on the developing sleeve 4b after the development is an excess charge or a large amount of toner having a small charge, and if this is repeated, only toner that is inappropriate for development remains on the development sleeve 4b. For this reason, at the time of the next printing, an image having a reduced density is output. Next, in the case of the method of performing ON / OFF of the developing DC only once, a large amount of toner is developed and cleaned only during the ON time, so that the toner adhering to the edge of the cleaning blade 6a is not stabilized. Further, since the toner image is developed only for a certain period of time, the charge of the toner on the developing sleeve 4b becomes uneven in the circumferential direction, which may cause density unevenness at the next printing. On the other hand, the method of repeating ON / OFF of the developing DC a plurality of times as in the present embodiment develops the toner on the developing sleeve 4b at a certain interval, so that the toner charge does not become non-uniform. Since the toner was supplied to the cleaning blade 6a little by little, it was confirmed that the attached toner was stabilized in the longitudinal direction of the cleaning blade 6a.

As a result of the above experiments, it was found that the method of the present embodiment can stably remove talc adhering to the surface of the photosensitive drum 1 and can perform stable development at the next printing. .

In this embodiment, the developing DC is turned ON / OF.
5, the DC component (charging DC) of the charging bias applied to the charging roller 2 as shown in FIG. 5 and the ON / OFF of the light emission of the exposure device 3 as shown in FIG. Develop the electrostatic latent image formed by turning OFF,
A plurality of belt-like toner images as shown in FIG. 4 may be formed. In the case of FIG.
At the same time as turning ON / OFF C, the charging AC is turned ON, and the developing DC is turned ON in correspondence with ON / OFF of the charging DC.
Let me. In the case of the one shown in FIG.
/ OFF, charging AC, charging DC, developing DC
Is turned on.

In the present embodiment, the effect of executing the cleaning sequence shown in FIG. 3 when image deletion has occurred has been confirmed. Development D as cleaning bias
C was set as shown in Table 1 below, and the cleaning sequence of FIG. 3 was performed. The transfer roller 5 has a diameter of 16 mm, t3 is set to an application time for two rotations of the transfer roller 5, and t4 is set to an application time for one rotation of the photosensitive drum 1. Also,
t5, which is the total of the repetition times of t1 and t2, is 250 s.
And

[0061]

Table 1 Application time Applied voltage Applied voltage t1 0.5ms -400V t2 99.5ms 0V t3 0.90s -400V t4 1.13s 1800V _PP (peak-to-peak voltage) Cleaning sequence in which application time and applied voltage are set as described above Was operated when an image flow was generated to the extent that characters were missing. As a result, the characters were clearly recognized by one operation, and the image flow was almost completely eliminated.

Referring to FIGS. 7 and 8, the control of the image forming apparatus will be described in detail with reference to FIG. FIG. 7 is a block diagram illustrating the control operation of the image forming apparatus, and FIG. 8 is a flowchart illustrating the control operation.

When printing is requested from a computer (not shown), the CPU 17 checks the printing rate and printing mode (continuous printing or intermittent printing) from the received data. In the present embodiment, if the number of jobs is one, the print mode is regarded as intermittent printing, and if the number of jobs exceeds that, it is regarded as continuous printing. When driving the main motor 16 to perform the image forming process, the CPU 17
From 8, the cumulative number of sheets and the average print rate in each print mode are read out, the print rate to be printed from now on is added to the average print rate, and the cumulative number of sheets to be printed, that is, 1 is added.
Comparing the number of image flow occurrences calculated by the above formulas (1) and (2) with the added number after addition, if the integrated number is equal to or greater than the number of image flow occurrences, the image deletion Then, the image forming operation is interrupted and the cleaning sequence is started, and a cleaning toner image is developed on the photosensitive drum 1. After that, 0 is substituted for the average print rate and the total number of prints in each print mode, and stored and stored in the storage unit 18.

As shown in the flowchart of FIG. 8, first, before entering the image forming operation, the printing rate G is recognized, and it is determined whether or not the printing rate is less than 8% (S1). If the printing rate G is 8% or more, it is determined that image deletion does not occur, and an image process is performed (S16).

Next, the number of jobs J is checked (S2).
If there is only one sheet, the intermittent cumulative number H and the intermittent average print rate QPT are read from the storage means 18 as intermittent printing (S11). If J is two or more, the continuous integrated printing number L and the continuous average printing rate RPT are read from the storage means 18 as continuous printing (S3).

Next, for continuous printing, 1 is set to L, RP
The print rate G is added to T (S4), the RPT is divided by L, and the result is multiplied by 500 defined by the above-mentioned equation (1) to calculate the number A of continuous print image flow occurrences (S5). On the other hand, in the case of intermittent printing, similarly, 1 is added to the intermittent cumulative number of sheets H, and the printing rate G is added to the intermittent average printing rate QPT (S12).
, And multiplying by 1600 defined by the above-mentioned equation (2) to calculate the number B of generated intermittently printed image flows (S1).
3).

Next, in the case of continuous printing, the continuous integrated printing L calculated in S5 is compared with the number A of continuous printed image flow occurrences (S6). If A is larger than L, L is stored in the storage means 18. The RPT is stored and stored (S7), and the image forming process is performed (S16). In S6, if L is equal to or larger than A, the cleaning sequence is executed (S6).
8). After that, 0 is substituted for RPT, QPT, L, and H, respectively (S9), and RPT, QPT, L,
H is stored and saved (S10). On the other hand, in the case of intermittent printing, the intermittent integrated print H calculated in S13 is compared with the number B of intermittently printed image flow occurrences (S14). If B is larger than H, H and QRT are stored in the storage means 18. The image is stored (S15), and the image forming operation is executed (S16). S1
If H is equal to or greater than B in 4, the cleaning sequence is executed (S8). Then, RPT, Q
0 is substituted for PT, L, and H, respectively (S9), and RPT, QPT, L, and H are stored and stored in the storage unit 18 (S1).
0).

In S6 and S14 described above, it is determined whether or not the number of sheets on which image deletion is likely to occur has been reached. If so, the cleaning sequence is immediately executed, and the factor is the image deletion factor on the photosensitive drum 1. Paper additives (such as talc) are removed together with the toner.

Next, one sheet is subtracted from the job J (S17).

If the job J remains (S1)
8) Return to S1 again to confirm the printing rate of the image to be printed next. If job J does not remain,
It ends.

By performing the above setting, the temperature 32.5
A durability test was carried out on a total of 10,000 sheets alternately between continuous printing of three sheets and single intermittent printing at a printing rate of 4% at an environment of 85 ° C. and a relative humidity of 85%, but no image deletion occurred. Further, the durability test of 10,000 sheets was similarly performed using only the single intermittent operation under the same other conditions, but no image deletion occurred.

In this embodiment, the storage means 18 stores
A method of updating and storing the integrated number of sheets and the average printing rate in the printing mode and determining the number of image-flow occurrences based on the information is adopted. For example, the rotation time of the photosensitive drum 1 when the transfer material P is printed is determined. It may be managed. The vertical axis of FIG. 9 is obtained by converting the “number of prints at which image deletion occurs” of FIG. 2 into “drum rotation time at which image deletion occurs”. From FIG. 9, for example, the same effect can be obtained by calculating the image flow occurrence rotation time as in the following equation (3) for continuous printing and as in equation (4) for intermittent printing.

In the case of continuous printing: Rotation time of occurrence of image deletion = 1800 × average printing rate of continuous printing (3) In the case of intermittent printing: Rotation time of occurrence of image deletion = 10000 × average printing rate of intermittent printing (4) The storage unit 18 of the present embodiment is provided on the image forming apparatus main body M side in the above description, but may be provided on the process cartridge 14 side as shown in FIG. 10 instead. Good. In this case, when the process cartridge 14 is mounted on the image forming apparatus main body M, the storage unit 18 stores
The CPU 17 on the image forming apparatus main body M side by the connector 19
Is to be connected. This is more effective because information is not lost when the process cartridge 14 is removed from the image forming apparatus main body M during printing, for example, in a paper jam process.

As described above, according to the present embodiment, the use state of the image forming apparatus is stored in the storage means 18 so that the time until image flow in a high-temperature and high-humidity environment can be reduced. Since the cleaning sequence can be obtained from the rotation time, the printing rate, the number of printed sheets, and the like, the cleaning sequence can be executed at an appropriate timing, and the image deletion can be effectively prevented.

By arranging the storage means 18 in the process cartridge 14, even if the process cartridge 14 is detached from the image forming apparatus main body M during use, information is not lost.

<Embodiment 2> In this embodiment, an environment detecting means for detecting temperature and humidity is provided in the image forming apparatus main body.
When the environment forming means detects a high humidity environment, a cleaning sequence is executed.

In the present embodiment, the environment detecting means is provided. As the environment detecting means, for example, when the primary charging is controlled at a constant current, the resistance value of the charging roller (charging member) 2 depending on the environment is determined. Since the primary voltage changes from the change, the humidity in the atmosphere can be predicted from the change value. In this case, it is not necessary to newly provide an environment detecting means, and it is possible to prevent an increase in cost. Further, in a graphic printer or the like that requires high image quality, it is necessary to use a charging member having a small resistance value environmental fluctuation, and the accuracy is poor when the above-described environment detecting means is employed. Therefore, it is better to use a temperature and humidity sensor for highly accurate measurement.

This embodiment will be described with reference to FIG. In FIG. 11, the same members as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 11, reference numeral 20 denotes a temperature / humidity sensor as environment detecting means for detecting the temperature / humidity of the environment. The temperature / humidity sensor 20 is disposed near the surface of the photosensitive drum 1 as shown in FIG. The measurement of the ambient temperature and humidity in the vicinity of the photosensitive drum 1 is performed, for example, even when the ambient temperature and humidity outside the image forming apparatus main body M is low, when the paper as the transfer material P absorbs moisture, This is because the moisture of the transfer material P evaporates due to the heat, and the moisture may adhere to the photosensitive drum 1 in some cases. In such a case, since the temperature / humidity sensor 20 can detect that the atmospheric humidity near the photosensitive drum 1 has increased, the cleaning sequence can be executed to prevent image deletion.

Reference numeral 21 denotes a non-volatile storage unit similar to that of the first embodiment, which is used to store the number of printed sheets until a cleaning sequence (the sequence shown in FIG. 3) is executed.

FIG. 12 is a block diagram illustrating the present embodiment. The temperature / humidity sensor 20 measures the ambient temperature / humidity and sends a signal to the CPU 17. If the CPU 17 determines from the signal that the use environment is a high humidity environment, it sets the number of printable sheets in the storage means 21 and thereafter subtracts 1 each time printing is performed. Control for executing the cleaning sequence is performed. When there is no risk of image deletion from the relationship between temperature and humidity, −1 is input to the storage unit 21.

The CPU 17 receives a signal from the temperature / humidity sensor 20 as shown in FIG.
When a signal representing an area indicated by R (a part indicated by gray) is received from the relationship between the temperature and the relative humidity of No. 3, the cleaning sequence is executed after 250 sheets have been printed from that point. Note that the same method as in Embodiment 1 was used for the cleaning sequence.

FIG. 14 shows a flowchart of the present embodiment. FIG. 2 shows a state where a computer (not shown) requests printing so that the image forming apparatus performs an image forming operation.

First, if there is no fear of image deletion, -1 is stored in the storage means 21.
This is confirmed (S21). If the number of printable sheets in the storage means 21 is -1, the temperature and humidity sensor 20 measures the ambient temperature and humidity and notifies the CPU 17 (S22). As a result, if there is no fear of image deletion (S23), an image forming operation is performed (S27), and the process ends.

However, if the ambient temperature and humidity are increasing at the time of S22, 250 sheets are set in the storage means 21 (S23, S24).

On the other hand, if the storage means 21 is not -1 in S21, there is a risk that the temperature and humidity have already risen and an image may flow, and one sheet is subtracted from the storage means 21 and stored in the storage means 21. (S25).

The storage means 2 is obtained by subtracting 1 from the storage means 21.
After storing it in 1 (S25), it is checked whether the storage means 21 is larger than 0 (S26). If the result is larger than 0, the image forming operation is performed as it is (S27), and the process ends.

If the number is 0, a cleaning sequence is executed (S28), -1 is stored in the storage means 21 (S29), an image forming operation is executed (S27), and the process is terminated. Accordingly, before the next image forming operation, the temperature and humidity of the atmosphere are measured by the temperature and humidity sensor 20.

The temperature / humidity sensor 20 of the present embodiment is similar to that of FIG.
As shown in FIG. 5, the process cartridge 14 may be provided. In this case, the temperature / humidity sensor 20 is connected to the CPU 17 by the connector 22 when it is mounted on the image forming apparatus main body M. Thus, even when the process cartridge 14 is removed from the image forming apparatus main body M during use and the process cartridge 14 is mounted on the image forming apparatus main body under another environment, the vicinity of the surface of the photosensitive drum 1 in the process cartridge 14 can be improved. Can be detected, the temperature and humidity sensor 20 is mounted on the image forming apparatus main body M side, and more accurate than when the process cartridge 14 is mounted on the image forming apparatus main body M. Strict measurement is possible, and signs of occurrence of image deletion can be accurately determined.

As described above, according to the present embodiment, by measuring the ambient temperature and humidity near the surface of the photosensitive drum 1 in the image forming apparatus main body M, it is possible to accurately detect the sign of image flow in a high humidity environment. The cleaning sequence can be executed at an appropriate timing, and the image deletion can be effectively prevented.

When the storage means 20 is provided in the process cartridge 14, when the process cartridge 14 having the photosensitive drum 1 is being used, the image forming apparatus main body M
The information on the photosensitive drum 1 is not lost even when the photosensitive drum 1 is removed from the photosensitive drum 1. That is, information on the photosensitive drum 1 moves with the movement of the photosensitive drum 1.

<Embodiment 3> This embodiment is characterized in that the execution time of the cleaning sequence is made variable in accordance with the number of jobs externally given to the image forming apparatus.

FIG. 16 is a diagram showing a schematic configuration of the image forming apparatus in the present embodiment, and FIG. 17 is a flowchart showing control of the operation of the image forming apparatus in the present embodiment. In FIG. 16, members and the like common to those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted.

A command given from the host computer (not shown) to the image forming apparatus includes the print content and the number of prints. At this time, the CPU 17
In S31 of No. 7, the number of prints J in the job is acquired. Then, in S2, the execution time of the necessary cleaning sequence (the sequence of FIG. 3) is calculated. According to the first embodiment, it has been found that the continuous printing at a low printing rate causes the sharpest image flow. Therefore,
From the equation (1) in the first embodiment, even when the average printing rate is as low as 1%, at the time of continuous printing of 500 sheets, t5 in FIG.
Since it is known that the execution of the cleaning sequence of s eliminates the image flow and obtains a satisfactory image quality, here, the time t5 during the cleaning sequence is calculated from the following equation from the number of prints J in the job.

T5 = J × 500 (ms) (5) Note that other t1, t2, t3, and t4 are the same as those in the first embodiment.
The same setting was used.

After performing the image forming operation in S33, in S34 the time t5 obtained by the equation (5) is obtained.
Then, a cleaning sequence is repeatedly performed by turning ON / OFF the developing DC, and the image forming operation is completed.

As described above, according to the present embodiment, the time t5 at which the ON / OFF of the developing bias in the cleaning sequence is repeated is made variable in accordance with the number J of jobs given to the image forming apparatus. The number J of
When the cleaning sequence needs to be performed for a longer time, and when the number of jobs J is small and the execution of the cleaning sequence in a short time is sufficient, an appropriate cleaning sequence execution time can be set.

The above settings are made to print one sheet at a printing rate of 4% in an environment of a temperature of 32.5 ° C. and a relative humidity of 85%.
10 continuous printing, 3 continuous printing, 4 continuous printing
When the durability test was performed for 000 sheets, no image deletion occurred.

Also, the ON time of the developing DC in the cleaning sequence, that is,
The width of the cleaning toner image on the photosensitive drum 1 (see FIG. 4)
4 shows the width of the belt-shaped toner image on the photosensitive drum 1 in the circumferential direction of the photosensitive drum 1. ) May be variable. That is, from equation (5), t5 = 500J = n (t1 + t2) (6). For example, in equation (6), when J = 1,
In the setting of the present embodiment, t1 = 0.5 ms, t2 = 9
Since 9.5 ms, t5 = 500 = n (t1 + t2) = 100n, that is, n = 5, and ON / OF of the developing DC is performed five times.
F is going.

Further, according to the present embodiment, t1 = 0.5 m
It is already known that the image flow can be eliminated if s and t2 are set to 99.5 ms.

Therefore, the ON time of the total development DC and the OFF time of the total development DC for each number of jobs are guaranteed, and the ON / OFF of the development DC is not limited for any number of jobs.
A cleaning sequence in which the number of times of OFF was fixed at 5 was performed.

More specifically, in the flowchart of FIG. 18, in the arithmetic processing in S42 of the CPU 17, the expression (5)
, T1 = 0.5 ms, t2 = 9
M is calculated from the following equation (7) into which 9.5 ms is substituted, and further, m = t5 ÷ 100 (7) t6 = 0.5 × m ÷ 5 (8) t7 = 99.5 × m ÷ 5 (9) t6 and t7 were calculated from the above equations (8) and (9). FIG.
Other steps in FIG. 8 are the same as those in the flowchart of FIG. That is, as shown in FIG. 18, t6 is a new ON time of the developing DC, and t7 is a new ON time of the developing DC.
A cleaning sequence in which t6 and t7 are repeated five times as the FF time is used, and the ON time of the developing DC is changed according to the number of prints J of the job. FIG. 19 shows a cleaning sequence according to the present embodiment.

In the flowchart shown in FIG.
U17 is controlled to print 1 sheet, 2 sheets continuous printing, 3 sheets continuous printing, and 4 sheets continuous printing in an environment of 32.5 ° C. and 85% relative humidity at a printing rate of 4%. A durability test was performed, but no image deletion occurred. That is,
Development D during the cleaning sequence depends on the number of jobs.
It was found that even if the ON time of C was changed, it was possible to prevent image deletion and obtain a satisfactory image.

Further, in the present embodiment, since it is not necessary to provide a storage means in the image forming apparatus main body M or the process cartridge 14, it is possible to provide an image forming apparatus with lower cost and excellent image quality.

In this embodiment, however, a storage means is provided in the image forming apparatus main body M or the process cartridge 14 for storing the number of jobs, and the cleaning sequence execution time and the cleaning sequence time are determined based on the information from this storage means. The ON time of the developing DC may be determined.

As in the second embodiment, the cleaning sequence is executed and the ON time of the current DC in the cleaning sequence is determined from the environment and the number of jobs by combining the environment detecting means. Good.

The cleaning sequence execution time,
Further, the ON time of the developing DC during the cleaning sequence varies depending on the material of the photosensitive drum 1, the charging roller 2, the cleaning blade 6a, and the like, and is therefore always fixed to the time (seconds) described in the present embodiment. Not something.

<Embodiment 4> This embodiment is characterized in that the cleaning sequence execution time is changed in accordance with the number of jobs given to the image forming apparatus, as in Embodiment 3 described above. However, instead of simply setting the cleaning sequence execution time in proportion to the number of jobs, if the number of jobs is extremely large or extremely small, the cleaning sequence execution time is kept constant. It is characterized in that an appropriate cleaning sequence execution time can be set. In addition,
The image forming apparatus according to the present embodiment is the same as the image forming apparatus according to the third embodiment (FIG. 16).

FIG. 20 is a flowchart showing the control of the cleaning sequence of the image forming apparatus according to the present embodiment. After acquiring the number of jobs J in S51 in the same figure, the number of jobs J is 500 in S52.
It is determined whether the number is equal to or less than the number. If the number of jobs J falls within this range, the unit of Expression (5) is adjusted to seconds in S53, and the number of jobs J is multiplied by 0.5 in S53, as in the third embodiment. Calculate the number t5 and calculate S5
At 5, the image forming operation is performed. In S6, it is determined whether the number of jobs J is 5 or more, and if it is 5 or more, a cleaning sequence for repeating the ON / OFF of the developing DC for t5 seconds is performed (S57).

If the number of jobs J is less than 5 in S56, a sufficient cleaning effect can be obtained only by a normal image forming operation, so that the cleaning sequence is not performed and the process ends.

If the number of jobs J is 500 or more in S52, if the cleaning sequence is simply performed by multiplying the number of jobs by 0.5 for t5 seconds,
Although a cleaning sequence of t5 = 250 seconds or more is performed, in actuality, any image flow is recovered by performing the cleaning sequence of t5 = 250 seconds. Not required.

Therefore, t5 = 250 in S54.
(S), and after the image forming operation, the cleaning of the photosensitive drum 1 is performed by executing the cleaning sequence for t5 = 250 seconds (S57).

As described above, in the present embodiment,
Instead of simply setting the cleaning sequence execution time in proportion to the number of jobs, if the number of jobs J is extremely large or extremely small, the cleaning sequence execution time is kept constant and a more appropriate cleaning sequence is performed. It is now possible to set the execution time.

Of course, in the present embodiment, as in the third embodiment, the number of jobs J is stored in the image forming apparatus main body M or the process cartridge 14, and the cleaning sequence is executed based on the information from the storage means. A form for determining the time is also conceivable.

Further, similarly to the second embodiment, the cleaning sequence execution time may be determined from the environment and the number of jobs by combining the environment detecting means.

Since the cleaning sequence execution time varies depending on the material of the photosensitive drum 1, the charging roller 2, and the cleaning blade 6a, it is not necessarily fixed to the number of seconds described in the present embodiment.

<Embodiment 5> This embodiment is characterized in that the cleaning sequence execution time is made variable in accordance with the length of the transfer material P to be printed by the image forming apparatus in the transport direction. The image forming apparatus according to the present embodiment is the same as the image forming apparatus according to the third embodiment (see FIG. 16). As the length detecting means for detecting the length of the transfer material P in the transport direction, for example, a plurality of paper feed cassettes each having a different mark for each different length in the transport direction are prepared. The transfer material P is read by reading the mark of the paper feed cassette when the transfer material P is mounted on the forming apparatus main body M.
And a sensor that calculates a sensor disposed in the transfer path of the transfer material P from the time difference between the leading end and the rear end of the transfer material P and the transfer speed. .

Even if continuous printing is performed on the transfer material P, there is actually a space between the first transfer material P and the second transfer material P. This gap is necessary when returning a small amount of toner adhering to the surface of the transfer roller 5 to the surface of the photosensitive drum 1, and such an operation is a necessary step for the image forming apparatus. . Then, since the additive does not adhere from the transfer material P between the sheets, the cleaning effect of the cleaning blade 6a is enhanced.

However, as the length of the transfer material P becomes longer, the time for which the photosensitive drum 1 contacts the transfer material P becomes longer, and the time from one sheet to the next becomes longer. Is increased, and image deletion is likely to occur. Therefore, the same effect as in the first embodiment is obtained by obtaining the relationship between the length of the transfer material P and the printing rate. In the present embodiment, the time between sheets is set to 1.5 seconds. The printing time per sheet when A4 landscape paper (length in the transport direction is 210 mm) is passed is 2.0 seconds.

In the third embodiment, a satisfactory image was obtained from the relationship between the number of prints J in a job set at a low printing rate of 1% and t5 in the cleaning sequence. P length L (mm),
Required t5 for the number of prints J in one job
(Second) is obtained by the following equation.

T5 = {1.5 × (J−1) + (J × 0.5)} × L ÷ 210 = (2 × J−1.5) × L ÷ 210 (10) FIG. 5 is a flowchart illustrating control of a cleaning sequence according to the present embodiment.

As in the third embodiment, the transfer material P is transmitted by a print command given from the host computer.
CPU that has acquired information on the length L and the number of jobs J
17 calculates the cleaning sequence execution time based on the above equation (10), and after the image formation ends, the developing D for t5 seconds.
A cleaning sequence is performed in which C is repeatedly turned ON / OFF.

As described above, according to the present embodiment, by changing the cleaning sequence execution time in accordance with the number of jobs J and the length L of the transfer material P, even in printing under any conditions, It is possible to obtain a stable image without image deletion.

At this time, the length L of the printed transfer material P may be stored in the storage means 20.

The cleaning sequence execution time may be determined from the environment and the length L of the transfer material P by combining the environment detecting means.

The cleaning sequence execution time varies depending on the material of the photosensitive drum 1, the charging roller 2, the cleaning blade 6a, and the like, and is not necessarily fixed to the number of seconds described in the present embodiment.

[0127]

As described above, according to the present invention,
The image deletion can be effectively prevented without shaving the image carrier, reducing the durability of the cleaning unit, and increasing the cost due to the provision of the heater.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating a schematic configuration of an image forming apparatus according to a first embodiment.

FIG. 2 is a diagram illustrating a relationship between a printing rate and the number of printed sheets where image deletion occurs in the first embodiment.

FIG. 3 is a diagram illustrating a development DC in Embodiment 1;
8 is a timing chart of a cleaning sequence when the cleaning operation is performed.

FIG. 4 is a diagram illustrating a state where cleaning toner is formed on the surface of a photosensitive drum.

FIG. 5 is a timing chart of a cleaning sequence when the charging DC is turned ON / OFF according to the first embodiment.

FIG. 6 is a timing chart of a cleaning sequence when exposure is turned ON / OFF in the first embodiment.

FIG. 7 is a block diagram of Embodiment 1.

FIG. 8 is a flowchart of a cleaning sequence according to the first embodiment.

FIG. 9 is a diagram illustrating a relationship between a printing rate and a drum rotation time during which an image flow occurs in the first embodiment.

FIG. 10 is a longitudinal sectional view illustrating a schematic configuration of a process cartridge according to the first embodiment.

FIG. 11 is a longitudinal sectional view illustrating a schematic configuration of an image forming apparatus according to a second embodiment.

FIG. 12 is a block diagram of Embodiment 2;

FIG. 13 is a diagram illustrating a relationship between air temperature and relative humidity according to the second embodiment.

FIG. 14 is a flowchart of a cleaning sequence according to the second embodiment.

FIG. 15 is a longitudinal sectional view illustrating a schematic configuration of a process cartridge according to a second embodiment.

FIG. 16 is a longitudinal sectional view illustrating a schematic configuration of an image forming apparatus according to Embodiments 3 and 4;

FIG. 17 is a flowchart of a cleaning sequence according to the third embodiment.

FIG. 18 is a flowchart of a cleaning sequence according to the third embodiment.

FIG. 19 shows Embodiment 4 in which development DC is turned ON / O.
6 is a timing chart of a cleaning sequence when FF is performed.

FIG. 20 is a flowchart of a cleaning sequence according to the fourth embodiment.

FIG. 21 is a flowchart of a cleaning sequence according to the fifth embodiment.

FIG. 22 is a longitudinal sectional view illustrating a schematic configuration of an image forming apparatus according to a fifth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image carrier (photosensitive drum) 2 Charging means (charging roller) 3 Exposure means (exposure device) 4 Developing means (developing device) 5 Transfer means (transfer roller) 6 Cleaning means (cleaning apparatus) 6a Cleaning blade 14 Process cartridge 14a Cartridge container 17 Control means (CPU, number detecting means) 18, 21 Storage means 20 Environment detecting means (temperature and humidity sensor) M Image forming apparatus main body P Transfer material

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Junichi Kato, Inventor 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Satoshi Inami 3-30-2 Shimomaruko, Ota-ku, Tokyo Kya Inside Non-corporation (72) Inventor Yusuke Nakazono 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Seiichi Shinohara 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. F-term (reference) 2H034 AA06 BA04 FA06

Claims (17)

[Claims] An image carrier is charged uniformly by a charging means, the charged image carrier surface is exposed by an exposure means to form an electrostatic latent image, and a developing means applies the electrostatic latent image to the electrostatic latent image. The toner is adhered and developed as a toner image, and the toner image on the surface of the image carrier is transferred onto a transfer material by a transfer unit. At the time of transfer, the toner remaining on the surface of the image carrier without being transferred to the transfer material is cleaned. Remove by means,
In an image forming apparatus having a series of image forming operations, a storage unit that stores information on a use state of the image forming device; a control unit that performs a cleaning sequence of the image carrier separately from the image forming operation; The control means, in the cleaning sequence,
The image carrier is rotated in accordance with the information stored by the storage unit, and the developing unit applies a belt-shaped cleaning toner image on the surface of the image carrier along the generatrix direction to the circumferential direction of the surface of the image carrier. Wherein the cleaning means removes these cleaning toner images from the surface of the image bearing member. 2. The image forming apparatus according to claim 1, wherein the information stored in the storage unit is a rotation time of the image carrier. 3. The image forming apparatus according to claim 1, wherein the information stored in the storage unit is a printing rate of a toner image formed on the transfer material. 4. The image forming apparatus according to claim 1, wherein the information stored in the storage unit is the number of transfer materials on which an image is formed. 5. The image forming apparatus according to claim 1, wherein the information stored in the storage unit is a length of the transfer material on which the image is formed in a transport direction. 6. A process cartridge in which at least one of said charging means, developing means and cleaning means and said image carrier are integrated into a cartridge container, and said process cartridge is detachably mounted. The image forming apparatus according to claim 1, further comprising: an image forming apparatus main body. 7. The image forming apparatus according to claim 6, wherein the storage unit is attached to the process cartridge. 8. The image forming apparatus according to claim 6, wherein the storage unit is attached to the image forming apparatus main body. 9. An electrostatic latent image is formed by uniformly charging the surface of the image carrier by a charging unit, exposing the charged surface of the image carrier by an exposure unit, and forming the electrostatic latent image on the electrostatic latent image by a developing unit. The toner is adhered and developed as a toner image, and the toner image on the surface of the image carrier is transferred onto a transfer material by a transfer unit. At the time of transfer, the toner remaining on the surface of the image carrier without being transferred to the transfer material is cleaned. Remove by means,
An image forming apparatus having a series of image forming operations, comprising: an environment detecting unit that detects temperature and humidity; and a control unit that performs a cleaning sequence of the image carrier separately from the image forming operation. Is, in the cleaning sequence,
The image carrier is rotated in response to a signal from the environment detecting means, and a belt-shaped cleaning toner image along the generatrix direction is formed on the image carrier surface by the developing means in a circumferential direction of the image carrier surface. Wherein the cleaning means removes these cleaning toner images from the surface of the image bearing member. 10. A process cartridge in which at least one of the charging unit, the developing unit, and the cleaning unit, and the image carrier are integrated into a cartridge container, and the process cartridge is detachably mounted. The image forming apparatus according to claim 9, further comprising: an image forming apparatus main body. 11. The image forming apparatus according to claim 10, wherein the storage unit is attached to the process cartridge. 12. The image forming apparatus according to claim 10, wherein the storage unit is attached to the image forming apparatus main body. 13. An electrostatic latent image is formed by uniformly charging the surface of the image carrier by a charging unit, exposing the charged surface of the image carrier by an exposure unit, and forming an electrostatic latent image on the electrostatic latent image by a developing unit. The toner is adhered and developed as a toner image, and the toner image on the surface of the image carrier is transferred onto a transfer material by a transfer unit. At the time of transfer, the toner remaining on the surface of the image carrier without being transferred to the transfer material is cleaned. Remove by means,
In an image forming apparatus having a series of image forming operations, a sheet number detecting unit for detecting the number of transfer materials on which an image is formed in one job; and a cleaning sequence of the image carrier separately from the image forming operation. Control means for performing, in the cleaning sequence,
The image carrier is rotated in response to a signal from the number-of-sheets detecting means, and a belt-shaped cleaning toner image along the generatrix direction is formed on the surface of the image carrier by the developing means in a circumferential direction of the image carrier surface. Wherein the cleaning means removes these cleaning toner images from the surface of the image bearing member. 14. An electrostatic latent image is formed by uniformly charging the surface of an image carrier by a charging unit, exposing the charged surface of the image carrier by an exposing unit, and forming the electrostatic latent image on the electrostatic latent image by a developing unit. The toner is adhered and developed as a toner image, and the toner image on the surface of the image carrier is transferred onto a transfer material by a transfer unit. At the time of transfer, the toner remaining on the surface of the image carrier without being transferred to the transfer material is cleaned. Remove by means,
In an image forming apparatus having a series of image forming operations, a length detecting unit that detects a length of the transfer material in a conveying direction, and a control unit that performs a cleaning sequence of the image carrier separately from the image forming operation. The control means, in the cleaning sequence,
The image carrier is rotated in response to a signal from the length detecting means, and a band-shaped cleaning toner image along the generatrix direction is formed on the surface of the image carrier by the developing means. An image forming apparatus, wherein the cleaning unit removes these cleaning toner images from the surface of the image bearing member. 15. The cleaning toner image is formed by turning off a charging bias of the charging unit, not exposing the exposing unit, and intermittently turning on a DC component of a developing bias of the developing unit. Claims 1, 2, 3, 4, 5, 6, 7,
The image forming apparatus according to 8, 9, 10, 11, 12, 13, or 14. 16. The cleaning toner image is obtained by intermittently turning on a DC component of a charging bias of the charging unit, not exposing the exposing unit, and continuously turning on a DC component of a developing bias of the developing unit. Forming, 1, 2, 3, 4, 5, 6, 7,
The image forming apparatus according to 8, 9, 10, 11, 12, 13, or 14. 17. The cleaning toner image according to claim 1, wherein the DC component of the charging bias of the charging unit is continuously turned on, the intermittent exposure of the exposure unit is performed, and the DC component of the developing bias of the developing unit is continuously connected. It is formed by ON, The claim 1, 2, 3, 4, 5, 6, 7,
The image forming apparatus according to 8, 9, 10, 11, 12, 13, or 14.