JP2017111393A - Image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of an image quality and reliability quality caused by deterioration of a developer.SOLUTION: An image formation device 1 comprises a data detection part 2 for detecting data related to a deterioration factor of toner. The image formation device is configured to store a discharge threshold in which the data related to the deterioration factor of the toner is considered, in a set information storage part 394 in advance. When a print start is instructed by a user, a print control part 391 reads out the discharge threshold according to the data related to the deterioration factor of the toner detected by the data detection part 2, from the set information storage part 394, then sets a difference between the discharge threshold and a printing rate to a discharge total amount. Then the print control part 391 executes refresh operation so that a larger amount of the toner is discharged to an area as the area has the lower printing rate.SELECTED DRAWING: Figure 10

Description

  The present invention relates to an image forming apparatus.

  2. Description of the Related Art An electrophotographic image forming apparatus is widely used for a copying machine, a printer, a facsimile machine, and a multifunction machine having two or more of these functions. An electrophotographic image forming apparatus forms a latent electrostatic image on the photosensitive surface of an image carrier by irradiating a laser beam, and attaches a developer charged by a developing machine along the latent electrostatic image. A recording medium through a step of forming a developer image on the photosensitive surface of the image carrier, a step of transferring the developer image to a recording medium such as paper, and a step of fixing the developer to the recording medium by heating or the like. An image is formed on.

  Not all of the developer attached to the image carrier is transferred to the recording medium, and untransferred developer that has not been transferred to the recording medium remains on the image carrier after the transfer process is completed. ing. Therefore, in the electrophotographic image forming apparatus, cleaning is performed to remove and collect the developer remaining on the photosensitive surface of the image carrier after the transfer of the developer image to the recording medium.

  Since the developer recovered from the photosensitive surface of the image carrier by cleaning can be reused, discarding it as it is increases the consumption of the developer and is not economical. Frequent replacement of the agent storage container is required, which increases the running cost of the image forming apparatus. Moreover, it is not preferable from the viewpoint of environmental protection.

  In order to solve such a problem, a developer recovery unit that switches the transport destination of the developer recovered from the photosensitive surface of the image carrier to a developing machine or a waste developer storage container according to conditions is provided. A conventional image forming apparatus has been proposed.

  On the other hand, the quality of the developer recovered from the photosensitive surface of the image carrier and reused may be deteriorated compared with the unused developer. The deterioration of the developer is caused by stress applied during the image forming process and paper dust. If the deteriorated developer is reused, it is easy to cause transfer loss or transfer rate deficiency during transfer, and the amount of wear on the photosensitive surface of the image carrier tends to increase. Reuse of the developer recovered from the surface causes deterioration in image quality and reliability quality.

  Further, when the developer containing the paper dust collected from the photosensitive surface of the image carrier is recycled into the developing machine, the paper dust (particularly calcium carbonate) charged in the developing machine is statically applied to the photosensitive surface of the image carrier. Since it adheres firmly with an electric force, a defective cleaning tends to occur on the photosensitive surface of the image carrier. This cleaning failure is particularly likely to occur when the printing rate (the ratio of the printed area to the area where the image can be formed) is low, and when printing of an image in which image data is biased in part of the image forming area continues. In addition, the occurrence rate increases at the print margins at both ends of the image.

  The cleaning failure is caused by insufficient lubrication of the photosensitive surface of the image carrier, and can be solved by performing a refresh operation for forcibly discharging the developer from the developing device onto the photosensitive surface of the image carrier.

  As an image forming apparatus that performs a refresh operation, the necessity of the refresh operation and the discharge amount of the developer are determined based on the print ratio of the developer image and the average print ratio of the entire image width calculated for each predetermined number of printed sheets. Has been conventionally proposed (see, for example, Patent Document 1).

  However, in the conventional image forming apparatus that performs the refresh operation, the necessity of the refresh operation and the discharge amount of the developer are determined based on the printing rate or the average printing rate, and the visible image deteriorated by being reused. No consideration is given to poor cleaning caused by the agent adhering to the photosensitive surface of the image carrier. Therefore, in the conventional image forming apparatus that performs the refresh operation, in the image forming apparatus that conveys the developer collected from the image carrier to the developing machine according to the conditions, the image quality and the reliability quality are effectively reduced. Cannot be prevented.

  The present invention has been made to solve such problems of the prior art, and an object thereof is to prevent deterioration in image quality and reliability quality due to deterioration of a developer.

In order to solve the above problems, according to one embodiment of the present invention, after transferring a developer image formed on an image carrier to a recording medium, the developer collected from the image carrier is discarded as a waste developer. A recovery developer transport section transported to a storage container or a developing machine; a data detection section that detects data relating to a deterioration factor of the developer recovered from the image carrier; and a printing rate of the developer image. Based on the printing rate acquisition unit to be acquired, the data relating to the deterioration factor of the developer detected by the data detection unit, and the printing rate acquired by the printing rate acquisition unit, it is forcibly discharged from the developing machine. A total discharge amount determining unit for determining the total discharge amount of the developer, and controlling the driving of the developing unit so as to discharge the amount of the developer corresponding to the total discharge amount determined by the total discharge amount determining unit. Print control Characterized by comprising and.

  According to the present invention, it is possible to prevent deterioration in image quality and reliability quality due to deterioration of the developer.

1 is a block diagram schematically illustrating a hardware configuration of an image forming apparatus according to an embodiment of the present invention. 6 is a graph showing a comparison between a non-electrostatic adhesion force of an initial toner and a non-electrostatic adhesion force of a deteriorated toner. It is a graph which shows the relationship between the smoothness of a transfer paper, and paper dust. 1 is a block diagram schematically illustrating a functional configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a diagram schematically illustrating a print engine of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged view illustrating an image forming unit according to an embodiment of the present invention and a toner recovery unit that transports toner recovered from a photosensitive drum. FIG. 2 is a block diagram schematically showing a functional configuration of a print engine according to an embodiment of the present invention. 6 is a table showing a method for setting a discharge threshold value stored in the image forming apparatus according to the embodiment of the present invention. FIG. 5 is a table showing an example of setting area division data stored in the image forming apparatus according to the embodiment of the present invention. FIG. 5 is a flowchart showing an operation procedure of a refresh operation executed by the image forming apparatus according to the embodiment of the present invention. FIG. 6 is a diagram showing a comparison between distribution of toner discharge amount in the image width direction when the collected toner rate is low and distribution of toner discharge amount in the image width direction when the collected toner rate is high. FIG. 6 is a diagram showing a comparison between the number of divisions of an image forming area in the image width direction when the collected toner ratio is low and the number of divisions of the image forming area in the image width direction when the collected toner ratio is high.

  Hereinafter, an embodiment of an image forming apparatus according to the present invention will be described. In this embodiment, an electrostatic latent image is formed on the photosensitive surface of a photosensitive drum (image carrier) with laser light, and charged toner (developer) is attached along the electrostatic latent image. By developing the image, a toner image (developer image) was formed on the photosensitive surface of the photosensitive drum, and then the toner image was transferred to a transfer paper (recording medium). Further, the toner image was transferred. An electrophotographic image forming apparatus that forms an image by fixing the adhered toner onto the transfer paper by applying pressure while heating the transfer paper will be described as an example.

  The image forming apparatus according to the present embodiment is configured to remove toner remaining on the photosensitive surface of the photosensitive drum by cleaning after performing an image forming operation. This is because even if the toner image formed on the photosensitive surface of the photosensitive drum is transferred to the transfer paper, not all of the toner adhering to the photosensitive surface of the photosensitive drum is transferred to the transfer paper.

  Further, the image forming apparatus according to the present embodiment discards the toner collected from the photosensitive surface of the photosensitive drum (in the present specification, this is referred to as “collected toner”) as it is or reuses it without discarding it. It has a hybrid recycling configuration to switch between.

  In addition, the image forming apparatus according to the present embodiment performs a refresh operation in which toner is forcibly discharged from the developing machine and adhered to the photosensitive surface of the photosensitive drum in order to eliminate the cleaning failure generated on the photosensitive surface of the photosensitive drum. Is supposed to run.

  The image forming apparatus according to the present embodiment takes into account the degree of deterioration of the toner collected from the photosensitive surface of the photosensitive drum and recycled into the developing device when the refresh operation is performed, and the toner discharged from the developing device. By regulating the total discharge amount of toner, it is possible to prevent poor cleaning caused by the deteriorated toner adhering to the photosensitive surface of the photosensitive drum, thereby preventing or suppressing deterioration in image quality and reliability quality. Is.

<Hardware Configuration of Image Forming Apparatus 1>
In order to achieve such an object, the image forming apparatus 1 according to the present embodiment has a hardware configuration shown in FIG. The image forming apparatus 1 according to the present embodiment includes an engine for realizing a printer, a scanner, and a facsimile in addition to the hardware configuration shown in FIG.

  As shown in FIG. 1, the image forming apparatus 1 according to the present embodiment includes the same configuration as a general server, personal computer, or the like. That is, in the image forming apparatus 1 according to the present embodiment, the CPU 10, the RAM 20, the ROM 30, the HDD 40, and the I / F 50 are connected via the bus 90.

  In addition, in the image forming apparatus 1 according to the present embodiment, in addition to this, various data detection units 2 that detect data relating to toner deterioration factors are connected to the bus 90.

  As shown in FIG. 1, the data detection unit 2 includes an in-machine temperature detector that detects the temperature inside the image forming apparatus, an outside temperature detector that detects the temperature outside the image forming apparatus, and the humidity inside the image forming apparatus. In-machine humidity detector for detecting, external humidity detector for detecting the humidity outside the image forming apparatus, print number counter for counting the number of printed sheets, double-sided printed number counter for counting the number of double-sided printed sheets, developing roller provided in the developing machine Development roller travel distance detector for detecting travel distance, supply toner amount detector for detecting the amount of toner supplied from the toner replenishing container to the developing machine, waste toner amount detector for detecting the amount of toner discarded into the waste toner storage container, Smoothness detector that detects the smoothness of transfer paper, toner replenishment time timer that counts toner replenishment time, and left time measurement that keeps time left since the previous operation Timer, etc. is provided.

  The defective cleaning of the photosensitive surface of the photosensitive drum occurs not only when the printing rate is low, but also when the deteriorated toner adheres to the photosensitive surface of the photosensitive drum. For this reason, the image forming apparatus 1 according to the present embodiment evaluates the degree of deterioration of the toner recycled into the developing device when the refresh operation is performed.

  As a deterioration factor of the toner, first, the cumulative travel distance of the peripheral surface of the developing roller provided in the developing machine since the previous refresh operation was performed (this is referred to as “cumulative development travel distance” in this specification). And the ratio of the collected toner contained in the developing machine (this is referred to as “collected toner ratio” in this specification). The collected toner rate can be calculated from the history of the printing rate and toner discard amount. When the printing rate is high and there is a large amount of toner discard history, the amount of toner remaining on the photosensitive surface of the photosensitive drum increases, so the recovered toner rate in the developing machine also increases, and the amount of toner discarded into the waste toner storage container is reduced. When the amount is large, the collected toner rate decreases.

  As the cumulative development travel distance becomes longer, the toner is agitated in the developing machine and is subjected to stress. Therefore, the charge amount is reduced due to the release of the additive and the powder is pulverized due to cracking, and the deterioration progresses. In particular, the toner recycled many times often deteriorates. For this reason, when image formation is performed using toner having a long cumulative development travel distance, the image quality tends to deteriorate.

  FIG. 2 shows a comparison of non-electrostatic adhesion between an unused toner (initial toner) and a toner (degraded toner) in which an additive is liberated or buried due to deterioration. However, this data shows the non-electrostatic adhesion force when the initial toner and the deteriorated toner are adhered to the polycarbonate pseudo-photosensitive material by the centrifugal separation method. As is apparent from this figure, the deteriorated toner loses the spacer effect as a result of the additive being released or buried, and the non-electrostatic adhesion to the photosensitive member is significantly greater than that of the initial toner. From this data, it can be seen that the deteriorated toner is less cleanable.

  Other examples of toner deterioration factors include in-machine temperature, in-machine humidity, out-of-machine temperature, and out-of-machine humidity. This is because the charge amount of the toner decreases under high temperature and high humidity. Further, since the internal temperature increases as the duplex printing ratio increases, the duplex printing ratio also becomes a deterioration factor of the toner.

  Other examples of toner deterioration factors include the number of sheets passed to the photosensitive drum and the developing machine, the printing pattern, the amount of toner supplied from the toner replenishing container to the developing machine, the toner replenishing time, and the disposal in the waste toner container. Toner amount. This is because if the number of sheets to be passed through the photosensitive drum and the developing machine is large, a large stress is applied to the toner, and the charge amount is reduced due to the liberation of the additive, and the pulverization is liable to occur. Further, when the amount of toner supplied from the toner supply container to the developing device is small or when the amount of waste toner into the waste toner container is small, the collected toner rate in the developing device becomes high.

  Still another example of the toner deterioration factor is the smoothness of the transfer paper on which the toner image is transferred. As shown in FIG. 3, the amount of paper powder mixed in the developing machine increases as the transfer paper has a lower smoothness. This is because the transfer paper having low smoothness is likely to cause the paper powder to fall from the surface of the transfer paper due to the frictional force acting during a series of printing operations. When the amount of paper dust mixed in the developing machine increases, the charge amount of the toner decreases and the image quality tends to deteriorate.

  Still another example of the deterioration factor of the toner is a leaving time from the previous operation. Toner that is left unstirred in the developing machine for a long time has a low charge amount, so that the image quality is likely to deteriorate.

  Since the image forming apparatus 1 according to the present embodiment includes the various data detectors 2 illustrated in FIG. 1, it is possible to accurately grasp the degree of toner deterioration. Therefore, the image forming apparatus 1 according to the present embodiment can perform a refresh operation in accordance with the degree of toner deterioration, and prevents deterioration in image quality and poor cleaning of the photosensitive drum due to toner deterioration. can do.

  In addition, a display unit 60, an operation unit 70, and a dedicated device 80 are connected to the I / F 50. The operation unit 70 is operated by a user of the image forming apparatus 1.

  The CPU 10 is a calculation unit and controls the operation of the entire image forming apparatus 1.

  The RAM 20 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 30 is a read-only nonvolatile storage medium, and stores various setting values and calculation formulas used when executing a refresh operation in addition to programs such as firmware. The various set values include a toner discharge threshold and image formation area division data. The toner discharge threshold will be specifically described later with reference to FIG. Further, the divided data of the image forming area will be specifically described later with reference to FIG.

  The HDD 40 is a non-volatile storage medium that can read and write information, and stores an OS (Operating System), various control programs, application programs, and the like.

  The I / F 50 connects and controls the bus 90 and various hardware and networks. The display unit 60 is a visual user interface for the user to check the state of the image forming apparatus 1 and is realized by a display device such as an LCD (Liquid Crystal Display). The operation unit 70 is a user interface such as a keyboard and a mouse for the user to input information to the image forming apparatus 1. The dedicated device 80 is hardware for realizing a dedicated function in the printer, scanner, and facsimile.

  In such a hardware configuration, a program stored in a storage medium such as the ROM 30, the HDD 40, or an optical disk (not shown) is read into the RAM 20, and the CPU 10 performs an operation according to the program loaded into the RAM 20, whereby the software control unit Is configured. A functional block that realizes the functions of the image forming apparatus 1 according to the present embodiment is configured by a combination of the software control unit configured as described above and hardware.

<Functional Configuration of Image Forming Apparatus 1>
Next, the functional configuration of the image forming apparatus 1 according to the present embodiment will be described with reference to FIG. FIG. 4 is a block diagram schematically illustrating a functional configuration of the image forming apparatus 1 according to the present embodiment. In FIG. 4, the electrical connection is indicated by solid arrows, and the flow of the transfer paper is indicated by broken arrows.

  As shown in FIG. 4, the image forming apparatus 1 according to the present embodiment includes a controller 100, a paper feed table 200, a print engine 300, a print paper discharge tray 400, an ADF (Auto Document Feeder) 500, a scanner engine 600, a document. A paper discharge tray 700, a display panel 800, and a network I / F 900. 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.

  The paper feed table 200 feeds transfer paper to the print engine 300 that is an image forming unit. The print engine 300 is an image forming unit that draws an image by executing an image forming output on the transfer paper conveyed from the paper feed table 200. As a specific aspect of the print engine 300 according to the present embodiment, there is an image forming mechanism using an electrophotographic system or an inkjet system. The image-formed transfer sheet on which an image is drawn by the print engine 300 is discharged to the print discharge tray 400. The print engine 300 is realized by the dedicated device 80 shown in FIG.

  The ADF 500 automatically transports a document set on a document table (not shown) to a scanner engine 600 serving as a document reading unit. The scanner engine 600 is a document reading unit including a photoelectric conversion element that converts optical information into an electrical signal, and optically scans a document automatically conveyed by the ADF 500 or a document set on a platen glass (not shown). This is a document reading unit that reads and generates image information. A document read by the scanner engine 600 is discharged to a document discharge tray 700. The ADF 500 and the scanner engine 600 are realized by the dedicated device 80 shown in FIG.

  The display panel 800 is an output interface that visually displays the state of the image forming apparatus 1 and is an input when the user directly operates the image forming apparatus 1 or inputs information to the image forming apparatus 1 as a touch panel. It is also an interface. That is, the display panel 800 includes a function for displaying an image for receiving an operation by the user. The display panel 800 is realized by the display unit 60 and the operation unit 70 shown in FIG.

  A network I / F 900 is an interface for the image forming apparatus 1 to communicate with other devices such as an administrator terminal and a personal computer via the network, and includes an Ethernet (registered trademark), a USB (Universal Serial Bus) interface, Interfaces such as Bluetooth (registered trademark), Wi-Fi (registered trademark), and FeliCa (registered trademark) are used. As described above, the image forming apparatus 1 according to the present embodiment receives image data for a print request and various control commands such as a print request from a terminal connected via the network I / F 900. The network I / F 900 is realized by the I / F 50 shown in FIG.

  The controller 100 is configured by a combination of software and hardware. Specifically, a software control unit and an integrated circuit configured by loading a control program such as firmware stored in a non-volatile storage medium such as the ROM 30 or the HDD 40 into the RAM 20 and performing an operation by the CPU 10 according to the program. The controller 100 is configured by hardware such as the above. 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. Further, the main control unit 110 controls the input / output control unit 150 and accesses other devices via the network I / F 900 and the network. The engine control unit 120 controls or drives driving units such as the paper feed table 200, the print engine 300, the print discharge tray 400, the ADF 500, the scanner engine 600, and the document discharge tray 700.

  The image processing unit 130 outputs drawing information based on image information described by PDL (Page Description Language), for example, document data or image data included in an input print job, under the control of the main control unit 110. Generate as information.

  Further, the image processing unit 130 processes image data input from the scanner engine 600 and generates image data. The image data is information stored in the image forming apparatus 1 as a result of the scanner operation or transmitted to another device via the network I / F 900 and the network. Note that the image forming apparatus 1 according to the present embodiment can directly input drawing information instead of image information, and can execute image forming output based on the directly input drawing information.

  The operation display control unit 140 displays information on the display panel 800 or notifies the main control unit 110 of information input via the display panel 800. The input / output control unit 150 inputs signals and commands input via the network I / F 900 and the network to the main control unit 110.

<Configuration of Print Engine 300>
Next, the print engine 300 of the image forming apparatus 1 according to the present embodiment will be described with reference to FIG. The print engine 300 shown in FIG. 5 is applied to the monochrome image forming apparatus 1, and its overall configuration is simplified.

  As shown in FIG. 5, the image forming apparatus 1 according to the present embodiment forms an image on the transfer paper P fed from the paper feed table 200 by the print engine 300, and then the transfer paper on which the image is formed. P is discharged to the print discharge tray 400. Note that the number of paper feed tables is not limited to one, and may be two or more.

  The print engine 300 according to the present embodiment includes a paper feed roller 210, a separation roller pair 220, a smoothness detector 230, a resist along a transfer paper P transport mechanism from the paper feed table 200 to the print paper discharge tray 400. A roller pair 240, an image forming unit 320, a fixing unit 370, a conveyance roller 250, and a discharge roller pair 410 are arranged.

  The image forming unit 320 includes a photosensitive drum 321, a charger 322, an optical writing device 330, a developing device 323, a transfer roller 340, a charge eliminator 324, a toner supply container 350, and a toner recovery unit 325.

  The charger 322 uniformly charges the photosensitive surface of the photosensitive drum 321. The optical writing device 330 irradiates the photosensitive surface of the photosensitive drum 321 with laser light to form an electrostatic latent image. The developing device 323 forms a toner image by attaching charged toner to the electrostatic latent image formed on the photosensitive surface of the photosensitive drum 321. The transfer roller 340 is pressed against the photosensitive surface of the photosensitive drum 321, and the photosensitive surface of the photosensitive drum 321 is transferred to the transfer paper P conveyed between the transfer roller 340 and the photosensitive surface of the photosensitive drum 321. The toner image formed on the toner is transferred.

  The static eliminator 324 neutralizes the photosensitive surface of the photosensitive drum 321 after the transfer of the toner image onto the transfer paper P is completed. The toner replenishing container 350 is a container for storing unused toner, and has a toner supply port communicating with the developing machine 323. Each time the toner concentration in the developing machine 323 falls below a predetermined value, the developing machine 323 is used. Supply an appropriate amount of toner. Therefore, the toner replenishing container 350 functions as an unused toner supply unit for the developing device 323.

  The toner collecting unit 325 collects the toner remaining on the photosensitive surface of the photosensitive drum 321 and conveys the collected toner to either the disposal side or the reuse side. The configuration of the toner recovery unit 325 will be described later.

  When forming an image, the image forming unit 320 first uniformly charges the photosensitive surface of the photosensitive drum 321 with the charger 322 in the dark. Next, the image forming unit 320 irradiates the photosensitive surface of the uniformly charged photosensitive drum 321 with light emitted from the optical writing device 330, and electrostatically writes an image on the photosensitive surface of the photosensitive drum 321. An electrostatic latent image is formed. Next, the image forming unit 320 forms a toner image on the photosensitive surface of the photosensitive drum 321 by making the electrostatic latent image visible with toner by the developing machine 323.

  Thereafter, the image forming unit 320 carries the transfer image P taken out from the paper feed table 200 into the transfer nip formed between the photosensitive surface of the photosensitive drum 321 and the transfer roller 340, The toner image is transferred onto the transfer paper P. At this time, a transfer bias is applied to the transfer roller 340, and a transfer electric field is formed between the photoconductor drum 321 and the transfer roller 340 by the transfer bias, and the transfer electric field causes the transfer from the photoconductor drum 321. The toner image is transferred to the paper P.

  The transfer paper P is taken out from the paper feed tray 200 by the paper feed roller 210, and after the skew is corrected by the registration roller pair 240, it is conveyed into the image forming unit 320 at a predetermined timing.

  The smoothness detector 230 includes a light emitting element 230a and a light receiving element 230b. The smoothing detector 230 irradiates the transfer paper P with the laser light emitted from the light emitting element 230a, and receives the reflected laser light from the transfer paper P with the light receiving element 230b. To do. The intensity of the reflected laser light incident on the light receiving element 230b varies depending on the thickness of the transfer paper P and the smoothness of the surface of the transfer paper P. Therefore, the thickness and smoothness of the transfer paper P can be detected from the output signal of the light receiving element 230b.

  When the toner image has been formed on the transfer paper P, the image forming unit 320 removes the toner remaining on the photosensitive surface of the photosensitive drum 321 by the toner recovery unit 325, and then removes the photosensitive surface of the photosensitive drum 321 from the static eliminator 324. To remove the charge, prepare for the next image formation, and shift to a standby state.

  The fixing unit 370 includes a heating roller 371 and a pressure roller 372, and heat and heat are transferred to the transfer paper P onto which the toner image conveyed into the fixing nip formed by the heating roller 371 and the pressure roller 372 is transferred. Pressure is applied to fix the toner image on the transfer paper P.

<Configuration of Toner Collection Unit 325>
Next, a detailed configuration of the toner recovery unit 325 according to the present embodiment will be described with reference to FIG. As shown in FIG. 6, the toner collection unit 325 according to the present embodiment includes a cleaning blade 325a, a collected toner conveying screw 325b, a collected toner conveying path 325c, a collected toner conveying path 325d, a collected toner guiding path 325e, a branch path 325f, The collected toner disposal screw 325g, the collected toner disposal conveyance path 325h, the collected toner reuse conveyance path 325i, the partition shutter 325j, and the like are configured.

  The cleaning blade 325a scrapes the toner remaining on the photosensitive surface of the photosensitive drum 321 by pressing the tip thereof against the photosensitive surface of the photosensitive drum 321 and collects the scraped toner in the collected toner conveyance path 325c.

  The collected toner conveying screw 325b conveys the collected toner collected in the collected toner conveying path 325c along the collected toner conveying path 325c toward the collected toner conveying path 325d. That is, the guide path 325e guides the collected toner conveyed from the collected toner conveyance path 325c by the collected toner conveyance screw 325b toward the branch path 325f along the collected toner conveyance path 325d. The branch path 325f is a branch point from the recovered toner transport path 325d to the recovered toner disposal transport path 325h and the recovered toner reuse transport path 325i.

  The collected toner disposal screw 325g conveys the collected toner along the collected toner disposal conveyance path 325h toward a waste toner storage container 326 that is a container for storing the discarded toner. The collected toner disposal conveyance path 325h is a conveyance path when the collected toner is discarded through the waste toner storage container 326. The collected toner reuse conveyance path 325i is a conveyance path when the collected toner is reused through the developing device 323.

  The partition shutter 325j is an open / close shutter provided in the branch path 325f to partition the collected toner disposal transport path 325h and the recovered toner reuse transport path 325i. The partition shutter 325j is closed in advance when collecting the toner remaining on the photosensitive surface of the photosensitive drum 321 when the collected toner is discarded as it is without being reused. When the toner is used, it is opened in advance when the toner remaining on the photosensitive surface of the photosensitive drum 321 is collected.

  In the toner collecting unit 325 configured as described above, when collecting the toner remaining on the photosensitive surface of the photosensitive drum 321, the toner collecting unit 325 first rotates the cleaning blade 325 a in the direction of the arrow shown in FIG. 6. The toner adhering to the photosensitive surface of the photosensitive drum 321 is scraped off, and the scraped toner is recovered in the recovery toner conveyance path 325c.

  The toner collecting unit 325 conveys the collected toner along the collected toner conveying path 325c toward the collected toner conveying path 325d by the collected toner conveying screw 325b, and the collected toner reaching the collected toner conveying path 325d is collected to the collected toner guiding path 325e. Thus, the toner is guided along the collected toner conveyance path 325d toward the branch path 325f.

  When the collected toner is discarded without being reused, the toner collecting unit 325 closes the partition shutter 325j in advance before the collected toner is transported to the branch path 325f, and the collected toner is discarded to the discarded toner. Then, the toner is discarded by being conveyed toward the waste toner storage container 326 along the collected toner disposal conveyance path 325h by the collected toner disposal screw 325g.

  On the other hand, when the collected toner is reused without being discarded, the toner collecting unit 325 opens the partition shutter 325j before the collected toner is conveyed to the branch path 325f, and uses the collected toner as the collected toner. The toner is reused by being conveyed toward the developing device 323 along the collected toner reuse conveying path 325i by gravity. As shown in FIG. 6, the developing machine 323 is provided with a developing roller 323a, and the toner in the developing machine 323 is attached to or discharged from the photosensitive surface of the photosensitive drum 321 by the developing roller 323a.

  As described above, the toner collection unit 325 according to this embodiment transports the toner collected from the photosensitive surface of the photosensitive drum 321 to the waste toner storage container 326 without reusing it, or transfers it to the developing machine 323 without discarding it. A recovery developer transport section for transport is configured.

  As shown in FIG. 4, in the waste toner storage container 326 according to the present embodiment, a waste toner measurement sensor 326a is attached to a connection portion with the collected toner waste conveyance path 325h. The image forming apparatus 1 according to the present embodiment can measure the amount of toner discarded in the waste toner storage container 326 based on the detection signal output from the waste toner measurement sensor 326a. ing.

  With this waste toner measurement sensor 326a, the image forming apparatus 1 according to the present embodiment can accurately estimate the amount of toner discarded in the waste toner storage container 326.

<Functional configuration of internal controller 390>
Next, a functional configuration of the internal controller 390 according to the present embodiment will be described with reference to FIG. FIG. 7 is a block diagram schematically illustrating a functional configuration of the print engine 300 according to the present embodiment. As shown in FIG. 7, the internal controller 390 according to the present embodiment includes a print control unit 391, a controller I / F 392, a data collection unit 393, a setting information storage unit 394, a print rate acquisition unit 395, and a total discharge amount determination unit 396. Consists of including.

  The print control unit 391 plays a role of controlling each unit of the internal controller 390 and gives a command to each unit of the internal controller 390. Further, the print control unit 391 controls driving of each unit constituting the print engine 300 based on information input from the engine control unit 120 via the controller I / F 392. As described above, the print engine 300 according to the present embodiment acquires information for controlling or driving each unit included in the print engine 300 from the engine control unit 120 via the controller I / F 392.

  In particular, the print control unit 391 according to the present embodiment functions as a refresh operation control unit that forcibly discharges toner staying in the developing device 323 to refresh the inside of the developing device 323. Also, the print control unit 391 according to the present embodiment opens and closes the partition shutter 325j provided in the toner recovery unit 325, and sets the transport destination of the toner recovered from the photosensitive surface of the photosensitive drum 321 to the developing device 323 or It functions as a transport control unit for the collected toner that is switched to the waste toner storage container 326.

  The controller I / F 392 is an interface for the internal controller 390 to communicate with the engine control unit 120.

  The data collection unit 393 collects various data related to the toner deterioration factor from the data detection unit 2 illustrated in FIG. Note that the image forming apparatus according to the present embodiment does not have to include all the detectors illustrated in FIG. 1, and may include a data detector other than the data detector illustrated in FIG. 1.

  The setting information storage unit 394 stores the discharge threshold illustrated in FIG. 8 and the divided data of the image forming area illustrated in FIG.

  Hereinafter, an example of the discharge threshold value stored in the setting information storage unit 394 will be described with reference to FIG. In this example, the discharge threshold value is set by forming a two-stage matrix. First, as shown in the upper column of FIG. 8, the temperature outside the image forming apparatus detected by the outside temperature detector is divided into three stages of low, medium, and high, and arranged on the vertical axis, A humidity outside the image forming apparatus detected by the external humidity detector is divided into three stages, low, medium and high, and arranged on the horizontal axis to create a first matrix consisting of nine 3 × 3 sections.

  In the second stage, as shown in the lower column of FIG. 8, the cumulative development travel distance detected by the development roller travel distance detector for each of the first to ninth sections obtained in the first stage. Is divided into three stages of 0 to 30 km, 0 to 30 km, 60 km or more and arranged on the vertical axis, and the smoothness of the transfer paper P detected by the smoothness detector is divided into three stages of low, medium and high. Are arranged on the horizontal axis to create a second matrix of 9 3 × 3 sections.

  And the appropriate discharge threshold value calculated | required by implementing experiment or simulation is set to each division which comprises a 2nd matrix. As a result, the temperature outside the image forming apparatus, the humidity outside the image forming apparatus, the cumulative development travel distance, and the discharge threshold considering the smoothness of the transfer paper P, which are toner deterioration factors, are stored in the setting information storage unit 394. be able to.

  In the example of FIG. 8, the discharge threshold value is set in consideration of four deterioration factors related to the toner. However, the discharge threshold value of the present invention only needs to consider at least one deterioration factor related to the toner. The gist of the present invention is not limited to the example of FIG. The deterioration factors relating to the toner are not limited to those shown in the example of FIG. 8, and data detected by various detectors can be used.

  Next, an example of the divided data of the image forming area stored in the setting information storage unit 394 will be described with reference to FIG. As described above, the poor cleaning of the photosensitive surface of the photosensitive drum 321 is particularly likely to occur when the printing rate is low, and when printing of an image in which image data is biased in a part of the image forming area continues, Incidence increases at the print margins at both ends.

  For this reason, even if the refresh operation is executed based on the average printing rate over the entire area where an image can be formed, it is difficult to efficiently eliminate the cleaning failure. For this reason, conventionally, the image forming area of the photosensitive drum 321 is divided into a plurality of small areas in the image width direction, and a refresh operation is performed by obtaining a printing rate for each of the divided small areas.

  In the example of FIG. 9, the image forming area of the photosensitive drum 321 is divided into ten small areas E1 to E10 in the image width direction. The setting information storage unit 394 stores the positions of both ends of each of the small areas E1 to E10.

  The printing rate acquisition unit 395 acquires the printing rate for each of the divided small regions E1 to E10 and the average printing rate for the entire area where an image can be formed. In the example of FIG. 9, the printing rate L1 of the small region E1, the printing rate L2 of the small region E2, the printing rate L9 of the small region E9 and the printing rate L10 of the small region E10 are 0%, the printing rate L3 of the small region E3, and the small The printing rate L8 of the region E8 is 1%, the printing rate L7 of the small region E7 is 2%, the printing rate L6 of the small region E6 is 3%, the printing rate L4 of the small region E4 and the printing rate L5 of the small region E5 is 4%. The average printing rate is 1.5%.

  The total discharge amount determination unit 396 takes in the data relating to the toner deterioration factor collected from the data detection unit 2 from the data collection unit 393, and sets the discharge threshold value and the image forming area according to the obtained data relating to the toner deterioration factor. Read from the storage unit 394. Further, the total discharge amount determination unit 396 takes in the average print rate for the entire area where the image can be formed from the print rate acquisition unit 395 and determines the difference between the discharge threshold and the average print rate as the total discharge amount.

  The print control unit 391 distributes the amount of toner corresponding to the total discharge amount determined by the total discharge amount determination unit 396 in accordance with the printing rate of each of the small areas E1 to E10. In the example of FIG. 9, the discharge threshold is 3%, the average printing rate is 1.5%, and the total discharge amount is 1.5%.

  As a result, the discharge amount R1 of the small region E1, the discharge amount R2 of the small region E2, the discharge amount R9 of the small region E9 and the discharge amount R10 of the small region E10 are 2.5%, and the discharge amount R3 and the small region of the small region E3. The discharge amount R8 of E8 is 2.0%, the discharge amount R7 of the small region E7 is 1.0%, the discharge amount R4 of the small region E4, the discharge amount R5 of the small region E5, and the discharge amount R6 of the small region E6 is 0%. It has become.

  The method for determining the total discharge amount and the method for distributing the total discharge amount will be described in more detail with reference to the flowchart of FIG.

<Image Forming Control Method Performed by Image Forming Apparatus 1>
As shown in FIG. 10, when the user gives an instruction to start printing (step S1), the data collection unit 393 causes the development roller 323a travel distance (development travel) detected by the development roller travel distance detector shown in FIG. (Distance) starts counting (step S2).

  Next, the print control unit 391 reads the cumulative development travel distance and the collected toner rate in the developing machine 323 from the data collection unit 393, and sets the discharge threshold A according to the read cumulative development travel distance and the collected toner rate. It reads out from the memory | storage part 394, and this read out discharge threshold A is determined as a discharge threshold at the time of performing refresh operation (step S3).

  In the discharge threshold A matrix shown in the right column of FIG. 10, unlike the example of FIG. 8, the vertical axis is the cumulative development travel distance, and the horizontal axis is the collected toner rate. As is apparent from this table, the discharge threshold A is set to a smaller value as the cumulative development travel distance is shorter and the collected toner rate is smaller, and is set to a larger value as the cumulative development travel distance is longer and the collected toner rate is larger. .

  Next, the printing rate acquisition unit 395 counts the average printing rate L (ave) with respect to the development travel distance (step S4).

  Next, the print control unit 391 reads the average printing rate L (ave) acquired in step S4 from the printing rate acquisition unit 395, and the read average printing rate L (ave) and the discharge threshold value determined in step S3. The magnitude relationship of A is determined (step S5).

  If it is determined in step S5 that the average printing rate L (ave) is smaller (Yes) than the discharge threshold A, the print control unit 391 performs a refresh operation on the difference between the average printing rate L (ave) and the discharge threshold A. It is set as the total discharge amount at the time (step S6).

  Then, after the previous printing operation is completed, the print control unit 391 has a low print rate for each of the plurality of small areas E1 to E10 obtained by dividing the image forming area of the photosensitive drum 321 with respect to the image width direction. The total discharge amount is distributed so that the toner discharge amount increases, and the toner discharge (refresh operation) from the developing device 323 is executed (step S7).

  Next, when the discharged toner reaches the transfer position, the print control unit 391 separates the transfer roller 340 from the photosensitive drum 321, and after the cleaning operation by the toner recovery unit 325 is completed, the print control unit 391 transfers the photosensitive drum 321 to the photosensitive drum 321. The roller 340 is brought into contact (step S8). In this way, by preferentially discharging to a region where the printing rate is low, defective cleaning can be efficiently prevented.

  Next, the print control unit 391 closes the partition shutter 325j provided in the toner collection unit 325, and conveys the collected toner collected from the photosensitive surface of the photosensitive drum 321 to the waste toner storage container 326 (step S9). . Thereafter, the flow returns to step S1.

  If it is determined in step S5 that the average printing rate L (ave) is equal to or greater than the discharge threshold A (No), the flow returns to step S1.

  After executing the refresh operation in step S7, the print control unit 391 supplies the same amount as the amount of toner discharged from the toner supply container 350 into the developer 323. As a result, even if the refresh operation is executed, the inside of the developing device 323 can be prevented from becoming insufficient in toner density, and a decrease in image density and occurrence of an abnormal image can be prevented.

  By the way, in the above-described embodiment, toner is preferentially discharged to a region where the printing rate is low to prevent cleaning failure. However, when a large amount of deteriorated recovered toner is discharged to the end of the cleaning blade 325a, On the other hand, it becomes easy to cause a cleaning defect.

  Therefore, in another embodiment of the present invention, as shown in FIG. 11, the toner discharge area is changed in consideration of the collected toner rate in the developing device 323. That is, as shown in the upper column of FIG. 11, when the collected toner rate in the developing device 323 is low, the toner is also discharged from the end of the cleaning blade 325a. On the other hand, as shown in the lower column of FIG. 11, when the collected toner rate in the developing machine 323 is high, the discharge of toner to the end of the cleaning blade 325a is eliminated, and the amount of the toner is discharged to the image forming area. It is distributed in the center part. By doing so, it is possible to more effectively prevent the photosensitive surface from being poorly cleaned.

  In still another embodiment of the present invention, as shown in FIG. 12, the division number of the image forming area is changed in consideration of the collected toner ratio in the developing device 323. That is, as shown in the upper column of FIG. 12, when the collected toner rate in the developing device 323 is low, the number of divisions of the image forming area is increased and the toner is discharged according to the printing rate. On the other hand, as shown in the lower column of FIG. 12, when the collected toner rate in the developing machine 323 is high, the number of divisions of the image forming area is reduced, and the image forming area is relatively located in the central portion. Allow toner to be expelled. Such a method can also effectively prevent defective cleaning of the photosensitive surface.

  Since the image forming apparatus according to the embodiment of the present invention performs the refresh operation of the developing device 323 in consideration of the degree of toner deterioration, the cleaning of the photosensitive surface of the photosensitive drum 321 can be effectively prevented, and the toner can be efficiently removed. It is possible to prevent a decrease in image quality and reliability quality due to deterioration.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Data detection part 10 CPU
20 RAM
30 ROM
40 HDD
50 I / F
60 Display Unit 70 Operation Unit 80 Dedicated Device 90 Bus 100 Controller 110 Main Control Unit 120 Engine Control Unit 130 Image Processing Unit 140 Operation Display Control Unit 150 Input / Output Control Unit 200 Paper Feed Table 210 Paper Feed Roller 220 Separating Roller Pair 230 Smoothness Detector 230a Light emitting element 230b Light receiving element 240 Registration roller pair 300 Print engine 320 Image forming unit 321 Photosensitive drum (image carrier)
322 Charger 323 Developing machine 323a Developing roller 324 Static eliminator 325 Toner recovery unit (recovered developer transport section)
326 Waste toner storage container (Discard developer storage container)
330 Optical Writing Device 340 Transfer Roller 350 Toner Replenisher (Developer Replenisher)
370 Fixing Unit 371 Fixing Roller 372 Fixing Roller 391 Print Control Unit 392 Controller I / F
393 Data collection unit 394 Setting information measurement unit 395 Print rate acquisition unit 396 Total discharge amount determination unit 400 Print output tray 410 Discharge roller pair 500 ADF
600 Scanner engine 700 Document output tray 800 Display panel 900 Network I / F
P Transfer paper (recording medium)

JP 2009-092903 A

Claims (9)

A recovered developer carrying section for transferring the developer image formed on the image carrier to a recording medium and then conveying the developer collected from the image carrier to a waste developer container or a developing machine; ,
A data detection unit for detecting data relating to a deterioration factor of the developer recovered from the image carrier;
A printing rate acquisition unit for acquiring a printing rate of the developer image;
Based on the data relating to the deterioration factor of the developer detected by the data detection unit and the printing rate acquired by the printing rate acquisition unit, the total discharge amount of the developer forcibly discharged from the developing machine A total discharge amount determining unit for determining
A print control unit that controls driving of the developing device so as to discharge the developer in an amount corresponding to the total discharge amount determined by the total discharge amount determination unit;
An image forming apparatus comprising: A storage unit that stores the discharge threshold of the developer according to the data relating to the deterioration factor of the developer;
The total discharge amount determining unit reads out the developer discharge threshold corresponding to the data relating to the deterioration factor of the developer detected by the data detection unit from the storage unit, and the read out from the storage unit. When determining the magnitude relationship between the discharge threshold of the developer and the printing rate acquired by the printing rate acquisition unit, and determining that the printing rate is smaller than the discharge threshold of the developer, The image forming apparatus according to claim 1, wherein a difference between the discharge threshold of the developer and the printing rate is determined as a total discharge amount of the developer.   The storage unit stores, as a developer discharge threshold value, the developer discharge threshold value in the form of a matrix according to data relating to a plurality of different deterioration factors of the developer. The image forming apparatus according to claim 2. The printing rate acquisition unit divides an image forming region, which is a region for forming the developer image on the image carrier, into a plurality of small regions in the image width direction, and the printing rate for each of the divided small regions. Get
The total discharge amount determining unit is configured to determine, based on the data relating to the deterioration factor of the developer detected by the data detecting unit and the printing rate acquired by the printing rate acquiring unit, for the plurality of small regions. The image forming apparatus according to claim 1, wherein a total discharge amount of the developer that is forcibly discharged from the apparatus is determined.   5. The print ratio acquisition unit changes the number of divisions of the developer image formation region according to data relating to the deterioration factor of the developer detected by the data detection unit. The image forming apparatus described in 1.   The data detection unit includes an in-machine temperature detector, an out-of-machine temperature detector, an in-machine humidity detector, an out-of-machine humidity detector, a printed sheet counter, a duplex printed sheet counter, a developing roller travel distance detector, a supplied toner amount detector, 6. The apparatus according to claim 1, further comprising one or more detectors selected from a waste toner amount detector, a smoothness detector, a toner replenishment time timer, and a standing time timer. 2. The image forming apparatus according to item 1.   7. The smoothness detector includes a light emitting element that irradiates the recording medium with laser light and a light receiving element that receives the laser light reflected by the recording medium. The image forming apparatus described. Further equipped with a developer supply section storing unused developer,
The print control unit discharges the unused developer from the developer supply unit into the developer when the developer is discharged in an amount corresponding to the total amount discharged from the developer. The image forming apparatus according to claim 1, wherein the image forming apparatus is supplied.   The print control unit executes the discharging operation of the developer from the developing device after the transfer of the developer image formed on the image carrier to the recording medium is completed. The image forming apparatus according to claim 1.