JP3837245B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic image forming apparatus.
[0002]
[Prior art]
In the conventional image forming apparatus, the timing of the filming removal operation is preset in the image forming apparatus in anticipation of the number of image formations that will affect the image due to filming formation. On the condition that it has been reached, the filming removal operation is performed by manually turning on the main switch again or pressing the operation input key (see JP-A-2-191980 and JP-A-6-301316).
[0003]
[Problems to be solved by the invention]
The reason why filming is formed on the photoreceptor is due to the mechanism of the image forming apparatus (due to the developer carrier and NOx generated by corona discharge), and the usage environment conditions (included in the paper type and paper) The type of transfer paper, such as additives, temperature, operation DUTY, etc.), but the ratio of contribution of the latter use environment conditions is large. The frequency at which the filming removal operation is performed (how many sheets of transfer paper or the like are to be performed every time image formation is performed) is determined empirically based on a standard operating environment. .
[0004]
Therefore, if the frequency is uniform, there is a problem that the influence of filming appears on the image before the time for performing the filming removal operation. On the other hand, if the filming removal operation is performed long before the influence of filming appears on the image, the number of filming removal operations will increase more than necessary, resulting in reduced productivity. .
[0005]
An object of the present invention is to provide an image forming apparatus capable of appropriately setting the frequency of filming removal operation according to the filming forming speed.
[0006]
[Means for Solving the Problems]
The invention described in claim 1 includes an image carrier, an optical writing device that forms an electrostatic latent image on the image carrier, a developing device that develops the electrostatic latent image into a toner image, An electrophotographic image forming apparatus comprising: a transfer device that transfers the toner image onto a sheet; and a filming removal device that scrapes off a filming material formed on the image carrier, and the image carrier. A sensor that measures the surface potential of a reference image on the body, a counter that counts the number of sheets on which the image has been formed, and the surface potential of the reference image when the reference image is formed at an arbitrary timing; The surface potential of the reference image when the reference image is formed again after performing a predetermined number of image formations is measured with the sensor, and the increase in the surface potential is determined from the difference between the measured surface potentials. said the rise Counter obtains the amount of increase in the surface potential per one sheet that is divided by the predetermined number of counting, obtained increased amount of size high Kusuru control means an operation frequency of the filming removing device in accordance with the When, it relates to an image forming apparatus characterized in that it comprises.
[0007]
Therefore, since the filming formation speed can be determined from the amount of increase in surface potential per sheet on which image formation has been performed, the amount of increase in surface potential per sheet on which image formation has been performed is determined. By increasing the frequency of operating the filming removal device as the value is larger, the frequency of the filming removal operation can be appropriately set according to the filming speed.
[0008]
According to a second aspect of the present invention, in the first aspect of the present invention, the control means has an upper limit value for the operation frequency of the filming removal apparatus.
[0009]
Therefore, the film formation is caused by the formation of abnormally fast filming under severe use environment conditions that are not permitted by the image forming apparatus (type of transfer paper such as paper type and additives, temperature, operation DUTY, etc.). It can be prevented that the time required for the ming removal operation becomes excessive and the productivity is lowered.
[0010]
The invention according to claim 3 is the invention according to claim 2, wherein the control means stops the image forming operation of the image forming apparatus when the operation frequency of the filming removal apparatus exceeds the upper limit value. To do.
[0011]
Therefore, it is possible to prevent abnormal images from being formed under severe use environment conditions that are not permitted by the image forming apparatus (type of transfer paper such as paper type and additives contained in paper, temperature, operation DUTY, etc.). .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a conceptual diagram showing a schematic configuration of an electrophotographic image forming apparatus 1 according to an embodiment of the present invention. In FIG. 1, reference numeral 2 denotes a belt-shaped image carrier (photosensitive member). The image carrier 2 is wound around a driving roller 3 and another appropriate number of supporting rollers 3 a, and an arrow is generated by the rotation of the driving roller 3. Driven in the A direction. The image carrier 2 moving in this way is uniformly charged to a predetermined polarity by the charger 4, and subsequently exposed by the imaging optical system 5 constituting the optical writing device to form an electrostatic latent image. The electrostatic latent image is developed when the image carrier 2 passes through the developing device 6 and is visualized as a toner image.
[0013]
On the other hand, transfer paper, which is an example of a sheet, is fed from the paper supply unit 7 toward the image carrier 2, and the toner image on the image carrier 2 is transferred onto the transfer paper by the discharging action of the transfer device 8. Next, the transfer paper is separated from the image carrier 2 while receiving the discharging action of the separation device 9, and the separated transfer paper is conveyed to the fixing device 11 by the conveyance belt 10 and the toner image is fixed on the transfer paper. After that, it is discharged out of the machine. The toner remaining on the image carrier 2 is removed by the cleaning device 12.
[0014]
While repeating a series of image forming operations as described above, a filming material is formed on the image carrier 2 (refer to JP-A-6-301316 for details of the cause of the filming material formation). . It is difficult to remove this filming substance with the cleaning device 12. Therefore, the image forming apparatus 1 includes a brush roller 13 that constitutes a filming removal apparatus. The brush roller 13 includes a brush 14 made of conductive metal fibers knitted on a base fabric, and a roller-shaped core material 15 around which the base fabric is wound. The brush roller 13 is supported so as to be movable toward and away from the image carrier 2 and is driven to rotate counterclockwise in FIG. A backup roller 16 is provided at a position facing the brush roller 13 with the image carrier 2 interposed therebetween.
[0015]
A surface potential which is a sensor for measuring the potential on the image carrier 2 is located upstream of the brush roller 13 of the movement of the image carrier 2 and downstream of the position where the electrostatic latent image is formed by the imaging optical system 5. A total of 17 is provided.
[0016]
When the filming is formed on the image carrier 2, the surface potential of the image carrier 2 is not easily attenuated by the exposure by the imaging optical system 5, and the attenuation is further reduced as the filming layer thickness increases. (See FIG. 2). As a result, the surface potential on the image carrier 2 after the exposure rises (see FIG. 3), and the image after transfer is markedly deteriorated on the transfer paper (in normal documents, there is no white character or picture). The part turns black.)
[0017]
Therefore, an electrostatic latent image serving as a reference image is formed on the image carrier 2, and the degree of filming can be determined by sampling and comparing changes in the surface potential over time. In the case of an analog copying machine or the like, the reference image is a member having a high light reflectance (for example, one painted white, or the like, so that the surface potential can be sufficiently attenuated in the portion exposed in the non-image area on the transfer paper, or A blank sheet etc. may be provided. In the case of a digital copying machine or the like, the output of the optical writing device may be made constant with the pattern width being a non-image area. When an electrostatic latent image (pattern) serving as a reference image is formed on the image carrier 2, the image carrier 2 moves and is sent to the surface electrometer 17 after a predetermined time. 17 is used to measure the surface potential.
[0018]
In the embodiment of the present invention, in this way, the degree of filming formation is detected, and control is performed to change the frequency of performing the filming removal operation in accordance with the filming formation speed. Hereinafter, such control will be described.
[0019]
FIG. 4 is a block diagram showing the electrical connection of the control system of the image forming apparatus 1 of the present invention. This control system includes a ROM 21 that stores various control programs and fixed data in the CPU 20, a RAM 22 that stores data in a rewritable manner as a work area of the CPU 20, an A / D converter 23, and an I / O for an input / output interface. The port 24 is connected to the bus 25. A surface potential meter 17 is connected to the A / D converter 23. In addition, an actuator such as a motor 26 that drives the driving roller 3 and a motor 27 that drives the brush roller 13 is connected to the I / O port 24. In addition, a display input device 28 including a display device such as an LED or a liquid crystal panel and an input device such as a key switch or a matrix touch switch is also connected to the CPU 20.
[0020]
FIG. 5 is a flowchart illustrating a process for controlling the frequency of performing the filming removal operation. In the embodiment of the present invention, the control means of the present invention is realized in the processing shown in this flowchart. First, the filming removal operation interval (set number of sheets) n, which is the number of sheets of transfer paper on which filming removal operation is performed each time an image is formed, is set to an initial value (step S1). After the image forming number exceeds the set number n, the power switch of the image forming apparatus 1 is turned on / off, or the display input device 28 displays that the image forming number exceeds the set number n. Then, after the manual operation from the input device is performed, the filming removal operation is performed.
[0021]
Next, an electrostatic latent image of the reference image is formed on the image carrier 2, and its potential V (initial potential: V0) is measured (step S2), and a number counter which is a counter prepared in the RAM 22 is measured. Reset (N = 0) (step S3).
[0022]
Then, image output is performed (step S4), and the number counter is incremented every time one image is output (N = N + 1) (step S5). When the value N of the number counter reaches N1 (step S6), The electrostatic latent image of the reference image is formed again on the image carrier 2, and the potential V1 is measured (step S7). Then, the increment “V1−V0” of the potential V1 from the initial potential V0 is divided by the number N1 of image formations during this period to obtain a potential increase dV per image formation (step S8).
[0023]
As is apparent from FIG. 3, the surface potential on the image carrier 2 and the filming lamination amount are in a substantially proportional relationship, and the filming lamination amount and the number of image outputs are the same. Therefore, the surface potential on the image carrier 2 and the number of output images are also approximated in a proportional relationship under the same conditions. The filming speed can be determined from the dV value.
[0024]
The ROM 21 stores a table as shown in FIG. 6 in which the dV value is associated with the set number n, and when the dV value does not exceed the predetermined upper limit value (N in step S9), in step S8. The set number n is changed to a value corresponding to the obtained dV value (step S10). Thereafter, the processing after step S3 is repeated thereafter.
[0025]
For example, when the dV value falls within the range of DV3 to DV4 in the example of FIG. 6, the set number n is set to 5000. Therefore, at this time, whenever the image output is performed for 5000 sheets, the motor 27 is driven and the filming removal process is performed by the brush roller 13.
[0026]
Therefore, the frequency of performing the filming removal operation can be appropriately set according to the filming formation speed.
[0027]
Note that if the value of the image forming number N1 is set to be small, fine control corresponding to environmental changes can be performed.
[0028]
When the image forming operation condition of the image forming apparatus 1 is severe (the amount of transfer paper additive is large, the temperature is high, the DUTY is large, etc.), the dV value becomes too large and the operation interval of the filming removal operation becomes excessively short The time required for the filming removal operation is excessively longer than the time required for the image forming operation, and the productivity of image formation is reduced. Therefore, a predetermined upper limit value (lower limit value of the set number n) is provided for the dV value (step S9) so that the productivity of image formation is not excessively lowered. When the dV value exceeds the upper limit value (below the lower limit value of the set number n), the image forming operation of the image forming apparatus 1 is stopped (step S11) so that an abnormal image is not output. Then, the fact that the image forming operation is stopped is notified by displaying it on the display device of the display input device 28 (step S12).
[0029]
For example, in the example of FIG. 6, when the upper limit value of the dV value is set to DV5, the image forming operation of the image forming apparatus 1 stops when the upper limit value of the dV value exceeds DV5.
[0030]
【The invention's effect】
According to the first aspect of the present invention, since the filming formation speed can be determined from the amount of increase in the surface potential per sheet on which image formation has been performed, the surface potential per sheet on which image formation has been performed. By increasing the frequency of operating the filming removal apparatus as the magnitude of the increase amount increases, it is possible to appropriately set the frequency of the filming removal operation according to the filming formation speed.
[0031]
According to a second aspect of the present invention, in the first aspect of the invention, severe use environment conditions that are not permitted by the image forming apparatus (type of transfer paper such as paper type and additives contained in the paper, temperature, operation DUTY, etc. ) Under an extremely fast filming, it is possible to prevent the time required for the filming removal operation from being excessively increased and the productivity from being lowered.
[0032]
According to a third aspect of the present invention, in the second aspect of the invention, severe use environment conditions that are not allowed for the image forming apparatus (type of transfer paper such as paper type and additives contained in the paper, temperature, operation DUTY, etc. ) Can be prevented.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a graph showing a relationship between an attenuation amount of a surface potential on an image carrier and a filming stack amount.
FIG. 3 is a graph showing the relationship between the surface potential of an image carrier and the amount of filming lamination.
FIG. 4 is a block diagram showing electrical connection of a control system of the image forming apparatus.
FIG. 5 is a flowchart illustrating processing for controlling the frequency of performing the filming removal operation of the image forming apparatus.
FIG. 6 is a table showing a table used for the control.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image carrier 6 Developing apparatus 8 Transfer apparatus 13 Filming removal apparatus 17 Sensor

Claims (3)

An image carrier;
An optical writing device for forming an electrostatic latent image on the image carrier;
A developing device for developing the electrostatic latent image into a toner image;
In an electrophotographic image forming apparatus provided with a transfer device that transfers the toner image onto a sheet,
A filming removal device for scraping off the filming material formed on the image carrier;
A sensor for measuring a surface potential of a reference image on the image carrier;
A counter that counts the number of sheets on which an image has been formed;
The sensor measures the surface potential of the reference image when the reference image is formed at an arbitrary timing and the surface potential of the reference image when the reference image is formed again after forming a predetermined number of images. and, determine the rise of the surface potential from the differential of the surface potential of each was measured to obtain the amount of increase in the surface potential per one sheet by the rise is the counter divided by the predetermined number of counting an image forming apparatus characterized by comprising: a high Kusuru control means an operation frequency of the filming removing device in accordance with the amount of increase in magnitude determined. The image forming apparatus according to claim 1, wherein the control unit has an upper limit value for an operation frequency of the filming removal apparatus. The image forming apparatus according to claim 2, wherein the control unit stops the image forming operation of the image forming apparatus when the operation frequency of the filming removing apparatus exceeds an upper limit value .

Images