JP2018010159A - Image forming apparatus, developer removing method, and control program for image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently remove a developer.SOLUTION: An image forming apparatus comprises: developing parts that each perform development by attaching a developer to an electrostatic latent image formed on a photoreceptor; a current detection part that detects a current in the developing parts; intermediate transfer parts that each transfer the developer attached to the photoreceptor to a transfer body; a transfer part that transfers the developer transferred to the transfer body to a recording medium; a developer removing part that mechanically removes the developer on the transfer body; and an applied voltage control part that applies a voltage to the transfer part on the basis of the value of the current, the situation of transfer of the developer to the transfer body and from the transfer part, and the situation of removal of the developer.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an image forming apparatus, a developer removing method, and a control program for the image forming apparatus.

  In recent years, there has been a tendency to digitize information, and image forming apparatuses such as printers and facsimiles used for outputting digitized information and scanners used for digitizing documents have become indispensable devices. Among such image forming apparatuses, for example, an image forming apparatus using an electrophotographic method is known.

  An electrophotographic image forming apparatus attaches toner, which is a developer, to an electrostatic latent image formed on a photoconductor, which is an image carrier, and transfers the developer to transfer paper, thereby transferring it to the transfer paper. Form an image. At that time, not all of the developer attached to the photosensitive member is transferred to the transfer paper. Therefore, the electrophotographic image forming apparatus needs to remove (clean) the remaining developer after the image forming operation (see, for example, Patent Document 1).

  In Patent Document 1, toner remaining on the conveyance belt is detected using an optical sensor, and a cleaning time for removing toner adhering to a transfer roller as a transfer unit is changed based on the detection result.

  In the technique of Patent Document 1, since the amount of toner remaining on the transfer belt is detected based on the amount of reflection by irradiating the conveyance belt with light, black toner may not be detected. Furthermore, since the optical sensor irradiates a part of the transfer belt with light, the amount of remaining toner cannot be detected over the entire transfer belt.

  The present invention has been made to solve such a problem, and an object thereof is to efficiently remove a developer.

  In order to solve the above problems, an aspect of the present invention provides a developing unit that performs development by attaching a developer to an electrostatic latent image formed on a photoreceptor, and current detection that detects current in the developing unit. An intermediate transfer unit that transfers the developer attached to the photosensitive member to a transfer member, a transfer unit that transfers the developer transferred to the transfer member to a recording medium, and the transfer member A developer removing unit that mechanically removes the developer, a value of the current, a transfer state of the developer in the transfer body and the transfer unit, and a removal state of the developer. And an applied voltage control unit for applying a voltage.

  According to the present invention, the developer can be efficiently removed.

1 is a block diagram showing a hardware configuration of an image forming apparatus according to an embodiment. FIG. 3 is a functional block diagram showing a functional configuration of the image forming apparatus according to the present embodiment. FIG. 2 is a diagram illustrating a configuration of a print engine according to the present embodiment. FIG. 3 is a diagram illustrating a configuration of an image forming unit according to the present embodiment. FIG. 3 is a diagram illustrating a toner movement path in the image forming apparatus according to the embodiment. The functional block diagram which shows the internal function of the main control part and input / output control part which concern on this embodiment. 6 is a flowchart showing a flow of processing for executing a cleaning operation according to the embodiment. The figure which illustrated the data table which shows the transfer ratio concerning this embodiment. The figure which illustrated the formula which shows the change of the transfer ratio concerning this embodiment. The figure which illustrated the data table which shows the transfer ratio concerning this embodiment. The figure which illustrated the formula which shows the change of the transfer ratio concerning this embodiment. FIG. 6 is a diagram showing a relationship between an accumulated amount of toner and a time for performing a cleaning operation according to the present embodiment. 6 is a data table showing the relationship between the amount of remaining toner and the time for performing a cleaning operation according to the present embodiment. 6 is a data table showing the relationship between the amount of remaining toner, the time for performing a cleaning operation, and the applied voltage according to the present embodiment. FIG. 3 is a diagram illustrating a toner movement path in the image forming apparatus according to the embodiment. 9 is a flowchart showing the flow of another process for executing the cleaning operation according to the embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this embodiment, an electrophotographic image forming apparatus will be described.

  FIG. 1 is a block diagram illustrating a hardware configuration of an image forming apparatus 1 according to the present embodiment. As shown in FIG. 1, an image forming apparatus 1 according to the present embodiment has the same configuration as an information processing apparatus such as a general PC (Personal Computer) or a server. That is, the image forming apparatus 1 according to the present embodiment includes a CPU (Central Processing Unit) 10, a RAM (Random Access Memory) 11, a ROM (Read Only Memory) 12, an engine 13, an HDD (Hard Disk Drive) 14, and an I / O. F15 is connected via the bus 19. Further, an LCD (Liquid Crystal Display) 16, an operation unit 17, and a dedicated device 18 are connected to the I / F 15.

  The CPU 10 is a calculation unit and controls the operation of the entire image forming apparatus 1. The RAM 11 is a volatile storage medium capable of reading and writing information at high speed, and is used as a work area when the CPU 10 processes information. The ROM 12 is a read-only nonvolatile storage medium, and stores programs such as firmware. The engine 13 is a print engine or the like that performs image formation output on the paper P that is a recording medium. The HDD 14 is a nonvolatile storage medium capable of reading and writing information, and stores an OS (Operating System), various control programs, application programs, and the like.

  The I / F 15 connects and controls the bus 19 and various hardware and networks. The LCD 16 is a visual user interface for the user to check the state of the image forming apparatus 1. The operation unit 17 is a user interface for the user to input information to the image forming apparatus 1, and is configured with a touch panel, a hard key, and the like in the present embodiment.

  The dedicated device 18 is hardware for realizing functions unique to the image forming apparatus 1, and is a print engine that executes image formation output on a paper surface and a scanner unit for reading an image on the paper surface.

  In such a hardware configuration, the CPU 10 performs calculations according to a program stored in the ROM 12 or a program read to the RAM 11 from a storage medium such as the HDD 14 or an optical disk, thereby configuring a software control unit. A functional block that realizes the function of the image forming apparatus 1 is configured by a combination of the software control unit configured as described above and hardware.

  Next, the functional configuration of the image forming apparatus 1 according to the present embodiment will be described with reference to FIG. FIG. 2 is a block diagram illustrating a functional configuration of the image forming apparatus 1 according to the present embodiment. As shown in FIG. 2, the image forming apparatus 1 according to the present embodiment includes a controller 100, an ADF (Auto Document Feeder) 101, a scanner unit 102, a paper discharge tray 103, a display panel 104, and a paper feed table. 105, a print engine 106, a paper discharge tray 107, and a network I / F 108.

  The controller 100 includes a main control unit 110, an engine control unit 120, an image processing unit 130, an operation display control unit 140, and an input / output control unit 150. As shown in FIG. 2, the image forming apparatus 1 according to the present embodiment is configured as a multifunction machine having a scanner unit 102 and a print engine 106. In FIG. 2, the electrical connection is indicated by solid arrows, and the flow of paper is indicated by broken arrows.

  The display panel 104 is an output interface that visually displays the state of the image forming apparatus 1, and as a touch panel, when the user directly operates the image forming apparatus 1 or inputs information to the image forming apparatus 1. It is also an input interface. That is, the display panel 104 includes a function for displaying an image for receiving an operation by the user. The display panel 104 is realized by the LCD 16 and the operation unit 17 shown in FIG.

  The network I / F 108 is an interface for the image forming apparatus 1 to communicate with other devices via the network, and uses an Ethernet (registered trademark) or a USB (Universal Serial Bus) interface. The network I / F 108 can communicate using the TCP / IP protocol. The network I / F 108 also functions as an interface for executing facsimile transmission when the image forming apparatus 1 functions as a facsimile. For this reason, the network I / F 108 is also connected to a telephone line. The network I / F 108 is realized by the I / F 15 shown in FIG.

  The controller 100 is configured by a combination of software and hardware. Specifically, a program stored in a ROM 12, a nonvolatile memory, and a nonvolatile storage medium such as the HDD 14 or an optical disk is loaded into a volatile memory (hereinafter, memory) such as the RAM 11. The CPU 10 performs an operation according to a program loaded in the RAM 11 or the like. The controller 100 is configured by a software control unit configured by the series of cooperation and hardware such as an integrated circuit. The controller 100 functions as a control unit that controls the entire image forming apparatus 1.

  The main control unit 110 plays a role of controlling each unit included in the controller 100, and gives a command to each unit of the controller 100. The engine control unit 120 serves as a driving unit that controls or drives the print engine 106, the scanner unit 102, and the like. The image processing unit 130 generates drawing information based on image information to be printed out under the control of the main control unit 110. The drawing information is information for drawing an image to be formed in the image forming operation by the print engine 106 as an image forming unit.

  The image processing unit 130 processes image data input from the scanner unit 102 to generate image data. This image data is information stored in the storage area of the image forming apparatus 1 as a result of the scanner operation or transmitted to another information processing terminal or storage device via the network I / F 108.

  The operation display control unit 140 displays information on the display panel 104 or notifies the main control unit 110 of information input via the display panel 104. The input / output control unit 150 inputs information input via the network I / F 108 to the main control unit 110. The main control unit 110 also controls the input / output control unit 150 to access the network I / F 108 and other devices connected to the network via the network.

  When the image forming apparatus 1 operates as a printer, first, the input / output control unit 150 receives a print job via the network I / F 108. The input / output control unit 150 transfers the received print job to the main control unit 110. When receiving the print job, the main control unit 110 controls the image processing unit 130 to generate drawing information based on document information or image information included in the print job.

  In the print job according to the present embodiment, in addition to image information in which image information to be output is described in an information format that can be analyzed by the image processing unit 130 of the image forming apparatus 1, parameters to be set at the time of image formation output Information is included. The parameter information is, for example, information such as duplex printing setting, aggregate printing setting, and color / monochrome setting.

  When drawing information is generated by the image processing unit 130, the engine control unit 120 controls the print engine 106 to form an image on the paper conveyed from the paper feed table 105 based on the generated drawing information. Let it run. That is, the image processing unit 130, the engine control unit 120, and the print engine 106 function as an image formation output unit. As a specific aspect of the print engine 106, an electrophotographic image forming mechanism is used in the present embodiment. A document on which image formation has been performed by the print engine 106 is discharged to a discharge tray 107.

  When the image forming apparatus 1 operates as a scanner, the operation display control unit 140 or input / output control is performed according to a user operation on the display panel 104 or a scan execution instruction input from another terminal via the network I / F 108. The unit 150 transfers the scan execution signal to the main control unit 110. The main control unit 110 controls the engine control unit 120 based on the received scan execution signal.

  The engine control unit 120 drives the ADF 101 and conveys the document to be imaged set on the ADF 101 to the scanner unit 102. In addition, the engine control unit 120 drives the scanner unit 102 and images a document conveyed from the ADF 101. If no original is set on the ADF 101 and the original is set directly on the scanner unit 102, the scanner unit 102 images the set original according to the control of the engine control unit 120. That is, the scanner unit 102 operates as an imaging unit, and the engine control unit 120 functions as a reading control unit.

  In the imaging operation, an imaging element such as a contact image sensor (CIS) or a charge-coupled device (CCD) included in the scanner unit 102 optically scans a document, and imaging information generated based on the optical information is generated. Is done. The engine control unit 120 transfers the imaging information generated by the scanner unit 102 to the image processing unit 130. The image processing unit 130 generates image information based on the imaging information received from the engine control unit 120 according to the control of the main control unit 110.

  Image information generated by the image processing unit 130 is acquired by the main control unit 110, and the main control unit 110 stores the image information in a storage medium attached to the image forming apparatus 1 such as the HDD 14. That is, the scanner unit 102, the engine control unit 120, and the image processing unit 130 work together to function as an image input unit. The image information generated by the image processing unit 130 is stored as it is in the HDD 14 or the like according to a user instruction, or is transmitted to an external device via the input / output control unit 150 and the network I / F 108.

  Further, when the image forming apparatus 1 operates as a copying machine, the image processing unit 130 generates drawing information based on imaging information received by the engine control unit 120 from the scanner unit 102 or image information generated by the image processing unit 130. To do. Based on the drawing information, the engine control unit 120 drives the print engine 106 as in the case of the printer operation.

  Next, the configuration of the print engine 106 according to the present embodiment will be described with reference to FIG. As shown in FIG. 3, the print engine 106 according to the present embodiment includes a configuration in which the image forming units 30 of the respective colors are arranged along a conveyance belt 301 that is an endless moving unit. That is what is said.

  That is, a plurality of papers are provided along a conveyance belt 301 that is an intermediate transfer body on which an intermediate transfer image to be transferred onto a sheet (an example of a recording medium) P that is separated and fed from a sheet feeding tray 25 by a sheet feeding roller 27 is formed. Image forming units are arranged. The plurality of image forming units (electrophotographic process units) are arranged as 30Y, 30M, 30C, and 30K (hereinafter collectively referred to as image forming unit 30) in order from the upstream side of the conveyance belt 301 in the conveyance direction.

  The paper P fed from the paper feed tray 25 is stopped once by the registration rollers 304 and sent out from the transport belt 301 to the image transfer position according to the image formation timing in the image forming unit 30. Then, the image is transferred onto the paper P by the secondary transfer roller 307 which is a transfer portion. The secondary transfer roller 307 has a cored bar, and a transfer bias is applied to the cored bar from a power supply unit 307E configured by a DC power source or an AC power source.

  The plurality of image forming units 30Y, 30M, 30C, and 30K have the same internal configuration except that the colors of the toner images to be formed are different. The image forming unit 30K forms a black image, the image forming unit 30M forms a magenta image, the image forming unit 30C forms a cyan image, and the image forming unit 30Y forms a yellow image. In the following description, the image forming unit 30Y will be described in detail, but the other image forming units 30K, 30M, and 30C are the same as the image forming unit 30Y. Therefore, for each component of the image forming units 30K, 30M, and 30C, instead of Y added to each component of the image forming unit 30Y, only the symbols distinguished by K, M, and C are displayed in the figure. The description is omitted.

  The conveyor belt 301 is an endless belt, that is, an endless belt that is stretched between a driving roller 305 and a driven roller 306 that are rotationally driven. The driving roller 305 is driven to rotate by a driving motor, and the driving motor, the driving roller 305, and the driven roller 306 function as a driving unit that moves the conveying belt 301 that is an endless moving unit. The conveyor belt cleaner 37 is a developer removing unit that is disposed so as to contact the conveyor belt 301 and mechanically scrapes off the toner remaining on the conveyor belt 301.

  At the time of image formation, the first image forming unit 30Y transfers a yellow toner image to the conveyance belt 301 that is rotationally driven. FIG. 4 is a cross-sectional view of the image forming unit according to the present embodiment. The image forming unit 30Y includes a photosensitive drum 31Y as a photosensitive member, a charging roller 32 disposed on the photosensitive drum 31Y, an optical writing device 310Y, a developing device 33, a photosensitive cleaner 34, a toner supply unit 36, and the like. ing. The optical writing device 310 is configured to irradiate the respective photosensitive drums 31Y, 31M, 31C, and 31K (hereinafter collectively referred to as “photosensitive drum 31”). FIG. 4 shows an optical writing device 310Y for irradiating the photosensitive drum 31Y with light.

  The photosensitive drum 31Y is obtained by sequentially laminating an organic photosensitive layer and a surface layer around a drum-shaped conductive support. The organic photosensitive layer is composed of a charge generation layer, a charge transport layer, and the like, and the thickness of the charge transport layer may be selected in accordance with the photoreceptor characteristics in the range of 10 to 40 μm. Further, an undercoat layer may be formed between the conductive support and the organic photosensitive layer in the photosensitive drum 31 as necessary.

  The charging roller 32 has a cored bar, and a charging bias is applied to the cored bar from a power supply unit 32E configured by a DC power source or an AC power source. Then, a discharge is generated in the gap between the charging roller 32 and the photosensitive drum 31Y through the charging gap, so that the photosensitive drum 31Y is uniformly charged.

  The optical writing device 310Y exposes light to the uniformly charged photosensitive drum 31Y based on the drawing information to form an electrostatic latent image. Examples of the optical writing method performed by the optical writing device 310 include a polygon scanning method and an LED array method.

  The developing unit 33 is a developing unit that visualizes the electrostatic latent image formed by the optical writing device 310Y by attaching toner to the photosensitive drum 31Y (hereinafter, referred to as “development”). The developing device 33 has a mandrel, and a developing bias is applied to the mandrel from a power supply unit 33E configured by a DC power source or an AC power source. Thereby, a yellow toner image is formed on the photosensitive drum 31Y. At this time, the toner supply unit 36 supplies toner to the developing device 33.

  This toner image is transferred onto the conveyance belt 301 by the action of a transfer unit including the primary transfer roller 35Y at a position (transfer position) where the photosensitive drum 31Y and the conveyance belt 301 come into contact or closest to each other. The primary transfer roller 35Y has a metal core, and a transfer bias is applied to the metal core from a power supply unit 35E configured by a DC power supply or an AC power supply.

  By this transfer, a yellow toner image is formed on the conveyance belt 301. After the transfer of the toner image is completed, unnecessary toner remaining on the outer peripheral surface of the photosensitive drum 31Y is wiped off by the photosensitive cleaner 34, and then light is irradiated again by the optical writing device 310Y to perform static elimination. The photoconductive drum 31Y after the photostatic discharge is on standby for the next image formation.

  Here, a high-voltage current is supplied to the charging roller 32, the developing device 33, the primary transfer roller 35, and the secondary transfer roller 307 by a power supply device. When the image forming apparatus 1 is a monochrome machine, the configuration is such that the conveyance belt 301 and the secondary transfer roller 307 are not included, and the toner is directly transferred from the photosensitive drum 31 to the paper P.

  In the image forming apparatus 1 configured as described above, the toner remaining on the conveyance belt 301 without being transferred to the paper P among the toner adhered on the conveyance belt 301 is cleaned. Next, a toner movement path in the image forming apparatus 1 according to the present embodiment will be described with reference to FIG.

FIG. 5 is a diagram illustrating a toner movement path in the image forming unit 30 according to the present embodiment. In FIG. 5, the same components as those in FIG. 4 are denoted by the same reference numerals, and redundant description is omitted. Also, T _A , T _B , T _C , and T _D shown in FIG.

Toner that is a developer is attached from the developing unit 33 to the photosensitive drum 31Y charged by the charging roller 32. Since an electrostatic latent image is formed on the charging roller 32, development with toner is performed when toner adheres to the electrostatic latent image. At this time, indicating the amount of toner adhered to the photosensitive drum 31Y at T _A. The toner adhering to the photosensitive drum 31Y is conveyed to a gap formed by the primary transfer roller 35Y and the photosensitive drum 31Y as the photosensitive drum 31Y rotates.

The toner is moved from the photosensitive drum 31Y to the transport belt 301 by the primary transfer roller 35Y. Accordingly, the primary transfer roller 35 functions as an intermediate transfer unit. In this case, it indicates the amount of toner that is moved to the conveyor belt 301 at T _B.

The toner on the conveyance belt 301 is moved onto the paper P by the secondary transfer roller 307. In this case, it indicates the amount of toner remaining on the conveyor belt 301 at T _C. The toner remaining on the conveyor belt 301 is scraped off by the conveyor belt cleaner 37, but some toner remains on the conveyor belt 301 without being completely removed. In this case, it indicates the amount of toner remaining on the conveyor belt 301 at T _D.

  The toner remaining on the conveyance belt 301 is moved along with the conveyance operation of the conveyance belt 301 and finally adheres to the secondary transfer roller 307. The operation of cleaning the toner in this embodiment indicates an operation of moving the toner onto the conveyance belt 301 by applying a voltage of a reverse bias to the secondary transfer bias to the secondary transfer roller 307. .

  In the present embodiment, the current measuring device 38 measures the developing current at the developing bias between the photosensitive drum 31Y and the developing device 33. Since the current measured at this time is generated by the movement of the charged toner, the amount of toner adhering to the photosensitive drum 31Y per development can be obtained based on the measured current value.

  Further, the transfer rate from the photosensitive drum 31Y to the transport belt 301, the transfer rate from the transport belt 301 to the paper P, and the toner removal rate by the transport belt cleaner 37 depend on the installation environment and use conditions of the image forming apparatus 1. . Therefore, a data table for determining the transfer rate and the removal rate is stored in the ROM 12 in advance, and the transfer rate and the removal rate are calculated according to the installation environment and usage status of the image forming apparatus 1 and remain on the conveyance belt 301. The amount of toner is calculated.

  Next, the function of calculating the toner amount according to the present embodiment will be described with reference to FIG. FIG. 6 is a functional block diagram showing internal functions of the main control unit 110 and the input / output control unit 150 according to the present embodiment.

  As shown in FIG. 6, the main control unit 110 according to the present embodiment includes a toner movement amount calculation unit 111, a toner transfer rate calculation unit 112, a toner removal rate calculation unit 113, a storage unit 114, and a cleaning execution control unit 115. . The input / output control unit 150 includes a current detection unit 151 and a temperature / humidity detection unit 152.

The toner movement amount calculation unit 111 calculates the amount (T _A ) of toner moved from the developing unit 33 to the photosensitive drum 31 based on the value of the developing current in the developing unit 33 detected by the current detection unit 151. The toner transfer rate calculation unit 112 determines the transfer rate based on the temperature and humidity values inside the image forming apparatus 1 detected by the temperature / humidity detection unit 152 and the value of the development current. Further, the toner transfer rate calculation unit 112, based on the transfer rate to the conveying belt 301 from the photosensitive drum 31Y based from the amount T _B and the conveyor belt 301 of the toner on the transfer rate to the sheet P the amount T _C of the toner calculate.

The toner removal rate calculation unit 113 determines the toner removal rate by the conveyor belt cleaner 37 based on the temperature and humidity values inside the image forming apparatus 1 detected by the temperature / humidity detection unit 152, and determines the removal rate. based calculates the amount T _D of toner. The storage unit 114 is a storage area for storing the amount of toner and the detected current value. The cleaning execution control unit 115 controls the execution of the cleaning operation for the secondary transfer roller 307.

  The current detector 151 causes the current measuring device 38 to detect the current value at the developing bias, and inputs the detected current value to the main controller 110. The temperature / humidity detection unit 152 causes the dedicated device 18 such as a temperature / humidity sensor to detect the temperature / humidity value inside the image forming apparatus 1 and inputs the detected temperature / humidity value to the main control unit 110.

  Next, a flow of processing for calculating the amount of toner remaining on the conveyance belt 301 according to the present embodiment will be described with reference to FIG. FIG. 7 is a flowchart showing a flow of processing for executing the cleaning operation according to the present embodiment.

  As shown in FIG. 7, when printing output is started based on the command information output from the main control unit 110 (S701), the developing device 33 attaches toner to the photosensitive drum 31Y by electrostatic force (hereinafter, referred to as “printing output”). , Described as “development”). The current detector 151 detects a current in a gap formed by the developing device 33 and the photosensitive drum 31Y during development (S702, development current detection).

The value of the current detected in the process of S702 is determined by the voltage of the toner applied to move the toner from the developing unit 33 to the photosensitive drum 31Y (hereinafter referred to as “development bias”). It is the current generated by the charge. Therefore, based on the value of the sensed current in the process of S702, it is possible to calculate the amount T _A of the toner attached to a photoconductive drum 31Y from the developing device 33 per developer once. Thus, the toner movement amount calculating section 111 calculates the _{T A} based on the value of the sensed current in S702 (S703).

Then, the toner transfer rate calculation unit 112, based on the value of _{T A} calculated in the process of S703, and calculates the amount _{T B} of the toner (S704). In the processing of S704, the amount _{T B} of toner transferred to the conveying belt 301 from the photosensitive drum 31Y is calculated. At this time, the amount T _B of toner transferred from the photosensitive drum 31Y to the conveyance belt 301 depends on the installation environment and the operation status of the image forming apparatus 1, the number of printed sheets, and the like.

  Therefore, as shown in FIG. 8, a data table indicating the ratio of toner transferred from the photosensitive drum 31Y to the conveyance belt 301 (hereinafter referred to as “transfer efficiency”) is stored in the ROM 12 in advance. This “transfer efficiency” is a value determined based on the relationship between the installation environment of the image forming apparatus 1 and the value of the current detected in S702.

  FIG. 8 is a data table showing the relationship between the temperature detected during operation of the image forming apparatus 1 according to the present embodiment and the current value detected when the developing bias is applied. Note that the Roman numerals used in the data table shown in FIG. 8 indicate the transfer efficiency determined based on the relationship between the installation environment of the image forming apparatus 1 and the current value detected in S702.

The amount T _B of toner transferred from the photosensitive drum 31Y to the conveying belt 301 by the number of printed sheets in the image forming apparatus 1 is changed. For this reason, as shown in FIG. 9, a formula indicating the change in the number of printed sheets in the image forming apparatus 1 and the transfer efficiency of the toner transferred from the photosensitive drum 31Y to the transport belt 301 is stored in the ROM 12 in advance. FIG. 9 is a diagram showing, for each toner color, an expression showing the number of printed sheets and the change in transfer efficiency of toner transferred from the photosensitive drum 31 to the conveyance belt 301 in the image forming apparatus 1 according to the present embodiment. .

As shown in FIGS. 8 and 9, in the processing of S704 calculates the T _B to account for changes in the transfer efficiency of the toner to be moved to the conveyor belt 301 from the photosensitive drum 31Y. It is calculated by “T _B = T _A × transfer efficiency for each toner color (FIG. 8) × change in transfer efficiency (FIG. 9)”. If coefficients determined in FIGS. 8 and 9 is "0.93", the amount T _B of toner transferred to the conveying belt 301 from the photosensitive drum 31Y is calculated in the toner transfer rate calculation unit 112 T The amount is 93% with respect to _A. Then, the toner transfer rate calculation unit 112, based on the _{T B} calculated in the process of S704, and calculates the amount _{T C} of the toner (S705).

In the processing of S705, the amount T _C of the toner remaining on the conveyor belt 301 without being transferred to the sheet P is calculated. At this time, the amount T _C of the toner remaining on the conveyor belt 301 is dependent of the installation environment and the operation status image forming apparatus 1, such as the number of printed sheets.

  Therefore, as shown in FIG. 10, the value is determined in advance based on the relationship between the installation environment of the image forming apparatus 1 and the value of the current detected in S702, and is transferred from the conveyance belt 301 to the paper P. A data table indicating the toner transfer efficiency is stored in the ROM 12.

  FIG. 10 is a data table showing the relationship between the temperature detected during the operation of the image forming apparatus 1 according to the present embodiment and the current value detected when the developing bias is applied. Note that Roman numerals used in the data table shown in FIG. 10 indicate values determined based on the relationship between the installation environment of the image forming apparatus 1 and the value of the current detected in S702.

Further, by the number of printed sheets in the image forming apparatus 1, the amount T _C of the toner remaining on the conveyor belt 301 is varied. For this reason, as shown in FIG. 11, the ROM 12 stores in advance an expression indicating the number of printed sheets in the image forming apparatus 1 and the change in transfer efficiency of toner transferred from the conveyance belt 301 to the paper P. FIG. 11 is a diagram illustrating, for each toner color, an expression indicating the number of printed sheets and the change in transfer efficiency of toner transferred from the conveyance belt 301 to the paper P in the image forming apparatus 1 according to the present embodiment.

As shown in FIGS. 10 and 11, in the process of S705, _TC is calculated in consideration of a change in transfer efficiency of toner transferred from the conveyance belt 301 to the paper P. It is calculated by “T _c = T _B −T _B × toner transfer efficiency (FIG. 10) × transfer efficiency change (FIG. 11)”. If coefficients determined in FIGS. 10 and 11 is "0.93", the amount _{T C} of the toner remaining on the conveyor belt 301, from the _{T B} which is calculated in the toner transfer rate calculation unit 112, _{T B} against The amount is obtained by subtracting the amount of 93% toner. Then, the toner removing ratio calculation unit 113, based on the _{T C} calculated in the process of S705, and calculates the amount _{T D} of toner (S706).

In the processing of S706, the amount _{T D} of toner remaining on the conveyor belt 301 is calculated. At this time, the amount T _D of toner remaining on the conveyor belt 301 is dependent of the installation environment and the operation status image forming apparatus 1, such as the number of printed sheets. Therefore, even in the process of S706, the removal efficiency determined from the value of the current sensed temperature sensed during the operation of the T _B and T _C image forming apparatus similar to the processing for calculating 1 when application of the developing bias A data table to be shown and an expression showing a change in toner removal efficiency are used. Specifically, the amount T _D of toner remaining on the conveyor belt 301 is calculated by the "change of T _{D =} T _C -T _C × detoning efficiency × removal efficiency". If a coefficient is determined using the data table and detoning efficiency indicating the removal efficiency is "0.95", the amount T _D of toner remaining on the conveyor belt 301, the toner remaining on the conveyor belt 301 from the amount _{T C,} an amount obtained by subtracting the amount of _{T C} 95% of the toner against.

In practice, the toner amounts T _A , T _B , T _C , and T _D are calculated for M, C, and K, respectively, by performing the same processing as described above. For each of the colors M, C, and K, a data table as shown in FIGS. 8 and 10 is stored in the storage unit 114. Then, transfer efficiency and removal efficiency are determined based on a data table prepared for each YMCK.

As for changes in transfer efficiency and removal efficiency, coefficients are calculated from the slopes of the straight lines corresponding to YMCK in FIGS. 9 and 11, and the toner amounts T _A , T _B , T _C , to calculate the T _D. 9 and 11 show the gradients of all colors of YMCK. For example, in the case of M colors, coefficients are calculated from the gradients indicated as “M” in FIGS.

Information of the amount _{T D} of the calculated toner in S706 is stored in the storage unit 114 (S707). The storage unit 114 stores the total value of the amount _{T D} of the toner is calculated in S706, respectively as the accumulation amount of the toner for YMCK. The cleaning execution control unit 115 determines whether or not to perform cleaning on the secondary transfer roller 307 based on the accumulated amount of toner stored in the storage unit 114 (S708).

When the toner accumulation amount is less than the predetermined amount (S708 / NO), the main control unit 110 executes the process again from S702. If the amount of accumulated amount _{T D} of the toner is equal to or greater than a predetermined amount (S708 / YES), the cleaning execution control unit 115 determines whether continuous printing output in the image forming apparatus 1 is performed (S709) . When continuous print output is being executed in the image forming apparatus 1 (S709 / YES), it is determined whether the amount of accumulated toner is equal to or greater than a predetermined amount (S710).

  In the process of S710, a predetermined toner accumulation amount is set so that the toner accumulation amount is larger than that in S708. This is because if the cleaning operation of the secondary transfer roller 307 is executed while the image forming apparatus 1 is continuously executing the print output, the printing efficiency may be lowered.

  When the accumulated amount of toner is less than the predetermined amount (S710 / NO), the cleaning execution control unit 115 sets the predetermined value of the accumulated amount of toner in the process of S708 smaller than that in the previous execution of the process of S708. , The process is executed again from S702. This is because it is considered that the toner remaining on the secondary transfer roller 307 increases after the image forming apparatus 1 continuously prints out.

  When the print output is not continuously executed in the image forming apparatus 1 (S709 / NO) or when the accumulated amount of toner is equal to or larger than the predetermined amount (S710 / YES), the cleaning execution control unit 115 performs the secondary operation. The time for performing the cleaning operation on the transfer roller 307 is determined (S711). FIG. 13 is a data table showing the relationship between the amount of toner remaining in the image forming apparatus 1 according to this embodiment and the time for performing the cleaning operation.

  In the data table shown in FIG. 13, a time determined based on the amount of accumulated toner is stored in the ROM 12. Further, the cleaning time of the secondary transfer roller 307 is proportional to the amount of accumulated toner as shown in FIG.

  In the present embodiment, the cleaning execution control unit 115 determines the time for performing the cleaning operation based on the accumulated amount of toner. Then, the cleaning execution control unit 115 applies a reverse bias voltage to the secondary transfer roller 307 for the time determined in S711 to execute cleaning (S712). Accordingly, the cleaning execution control unit 115 functions as an applied voltage control unit that controls the voltage applied to the secondary transfer roller 307.

When the cleaning is completed, the cleaning execution control unit 115 resets the accumulated amount of toner stored in the storage unit 114 and ends this processing. In the process of S711, the cleaning execution control unit 115 may be configured to determine the voltage to be applied in order to perform a cleaning operation based on the accumulated amount of the amount T _D of the toner. In such a case, a data table in which the applied voltage is determined based on the toner accumulation amount shown in FIG.

  Further, the flowchart of FIG. 7 can be similarly applied to a monochrome electrophotographic image forming apparatus 1 as shown in FIG. In the image forming apparatus 1 shown in FIG. 15, the cleaning execution control unit 115 determines the voltage application time and the voltage value to be applied according to the flowchart of FIG. 7 when cleaning the primary transfer roller 35.

In the flowchart of FIG. 7, the execution of the cleaning operation is controlled based on the amount of toner remaining on the secondary transfer roller 307 per one development, but this is detected during development as shown in the flowchart of FIG. that when the cumulative value of the value of the current exceeds a predetermined value, it may be configured to calculate the amount T _a of the toner.

  FIG. 16 is a flowchart showing the flow of another process for executing the cleaning operation according to this embodiment. In FIG. 16, steps that perform the same processing as in FIG. 7 are given the same reference numerals, and redundant descriptions are omitted.

When the current at the time of development is detected by the current detection unit 151 (S702), the cleaning execution control unit 115 cumulatively stores the detected current value in the storage unit 114 (S1601). When the cumulative value of the current value stored in the storage unit 114 is equal to or greater than a predetermined value (S1602 / YES), the cleaning execution control unit 115 is based on the current value stored in the storage unit 114. to calculate the amount _{T a} toner (S703).

  From S703 to S711, the same processing as in FIG. 7 is performed according to the order shown in FIG. In the flowchart shown in FIG. 16, the standard for determining the execution of the cleaning operation is the current value. Therefore, an error from the amount of toner that actually remains is corrected based on the elapsed time from the previous cleaning.

  The cleaning execution control unit 115 determines the number of printed sheets until the cumulative value of the current value stored in the storage unit 114 in S1602 exceeds a predetermined value, the temperature and humidity conditions of the image forming apparatus 1, and the current detected during development. Correction is performed based on the value of. It should be noted that a data table for predicting an error from the actually remaining amount of toner may be provided based on these conditions. Further, the number of printed sheets may be calculated based on the number of times the toner has been transferred to the recording medium.

Further, without correction to set the transfer efficiency of toner transferred from the conveyor belt 301 to the sheet P to the minimum, and sets the removal efficiency of the toner to be removed from the conveyor belt 301 to a minimum, T _C and T _D may be calculated. When calculating the T _C and T _D based on such conditions, the amount of toner remaining on the conveyor belt 301 is calculated larger than the actual, reliably removed that the toner adhering to the secondary transfer roller 307 Is possible.

  The cleaning execution control unit 115 performs correction in S1603 and executes a cleaning operation on the secondary transfer roller 307 (S712). When the cleaning is completed, the cleaning execution control unit 115 resets the accumulated value of the current values stored in the storage unit 114, and ends this process.

  As described above, in the image forming apparatus according to the present embodiment, the calculation is performed in consideration of the toner transfer status and the removal status in a series of operations of the image forming output based on the current value detected during development. The time for performing the cleaning operation is controlled in accordance with the amount of toner. Therefore, the toner adhering to the transfer roller can be efficiently removed based on the amount of toner actually supplied to the photoreceptor.

1 Image forming apparatus 10 CPU
11 RAM
12 ROM
13 Engine 14 HDD
15 I / F
16 LCD
17 Operation unit 18 Dedicated device 19 Bus 25 Paper feed tray 27 Paper feed roller 30 Image forming unit 31 Photosensitive drum 32 Charging roller 33 Developer 34 Photoconductor cleaner 35 Primary transfer roller 36 Toner supply unit 37 Conveying belt cleaner 38 Current measuring device 100 Controller 101 ADF
102 Scanner unit 103 Paper discharge tray 104 Display panel 105 Paper feed table 106 Print engine 107 Paper discharge tray 108 Network I / F
110 Main control unit 111 Toner movement amount calculation unit 112 Toner transfer rate calculation unit 113 Toner removal rate calculation unit 114 Storage unit 115 Cleaning execution control unit 120 Engine control unit 130 Image processing control unit 140 Operation display control unit 150 Input / output control unit 151 Current detection unit 152 Temperature / humidity detection unit 301 Conveyor belt 304 Registration roller 305 Drive roller 307 Secondary transfer belt

JP 2011-191336 A

Claims (8)

A developing unit for developing the electrostatic latent image formed on the photosensitive member by attaching a developer;
A current detection unit for detecting current in the developing unit;
An intermediate transfer portion for transferring the developer attached to the photosensitive member to a transfer member;
A transfer section for transferring the developer transferred to the transfer body to a recording medium;
A developer removing unit that mechanically removes the developer in the transfer body;
An applied voltage control unit that applies a voltage to the transfer unit based on the value of the current, the transfer state of the developer in the transfer body and the transfer unit, and the removal state of the developer;
An image forming apparatus comprising: The applied voltage controller is
The image forming apparatus according to claim 1, wherein a voltage having a reverse bias is applied to the transfer unit in reverse to a voltage when the developer is transferred to the recording medium. The applied voltage controller is
A time for applying the voltage is calculated based on the current value, the transfer state in the transfer body and the transfer unit, and the removal state, and the voltage is applied based on the calculated time. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The applied voltage controller is
The time for applying the voltage is calculated based on the number of times the developer has been transferred to the recording medium, and the voltage is applied based on the calculated time. The image forming apparatus described in 1. The applied voltage controller is
Calculating a value of the voltage to be applied to the transfer portion based on a value obtained by accumulating the value of the current detected during a predetermined period, and applying the voltage based on the calculated voltage value. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. Includes a temperature and humidity detector that detects the temperature and humidity inside the image forming device,
The applied voltage controller is
6. The voltage value is calculated based on the detected temperature / humidity value, and the voltage is applied based on the calculated voltage value. The image forming apparatus described in the item. The developer is attached to the electrostatic latent image formed on the photoconductor and developed.
The current is detected in the developing unit where the development is performed,
Transferring the developer adhered to the photosensitive member to a transfer member;
Transfer the developer transferred to the transfer body to a recording medium,
Mechanically removing the developer in the transfer body;
Applying a voltage to the transfer unit based on the value of the current, the transfer state of the developer in the transfer unit that transfers the transfer body and the developer to a recording medium, and the removal state of the developer. A developer removing method. A developer is attached to the electrostatic latent image formed on the photoconductor for development;
Detecting a current in a developing section where the development is performed;
Transferring the developer adhered to the photosensitive member to a transfer member;
Transferring the developer transferred to the transfer body to a recording medium;
Mechanically removing the developer in the transfer body;
Applying a voltage to the transfer unit based on the value of the current, a transfer state of the developer in a transfer unit that transfers the transfer body and the developer to a recording medium, and a removal state of the developer; ,
And a control program for the image forming apparatus.