JP2010085859A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which eliminates deteriorated toner. <P>SOLUTION: When a value obtained by dividing a dot counted value expressing toner consumption calculated from image data that is the basis of latent image formation by a latent image forming part by operating time of a developing device is under B, a controller decides whether a density recovery mode is set to on or set to off by progressing to a step S402. When deciding that the density recovery mode is set to on in the step S402, the controller performs the density recovery mode, so as to form a black solid image and discharge the deteriorated toner to the outside of a copying machine by jumping to a step S404. When deciding that the density recovery mode is set to off, the controller performs display that a user had better set the density recovery mode on a display panel in step S405. When a user designates the density recovery mode in response to the display, the controller performs the density recovery mode in a step 304, so as to form the black solid image and discharge the deteriorated toner to the outside of the copying machine. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus.

  As a technique for suppressing changes in image quality over time in an image forming apparatus employing an electrophotographic system, for example, when the film pressure of the photoconductor has decreased, the bias voltage applied to the photoconductor is increased so that toner adheres to the photoconductor. A technique for keeping the rate constant is disclosed (see, for example, Patent Document 1).

In addition, the change in the state of the photoconductor is detected by a resistance value, etc., and the charging voltage and charging current of the photoconductor, and the static elimination voltage and static elimination current for neutralizing the photoconductor are adjusted to improve the adhesion rate of the toner to the photoconductor. Or a technique for improving the removal rate of toner from the photoreceptor (see, for example, Patent Document 2).
JP 05-257354 A JP 2006-301622 A

  When an image is formed by the image forming apparatus, an image having a large non-image area occupation ratio may be formed repeatedly. In an image forming apparatus adopting an electrophotographic system, when this occurs, the toner in the developing unit is not consumed or the amount of consumption is small, so that no new toner is supplied to the developing unit. The toner in the developing device stays in the developing device for a long time. As a result, the external additive around the toner may be peeled off or embedded in the toner in response to the stirring operation in the developing device. When the latent image on the surface of the photosensitive member is developed with toner in which the external additive has been peeled off or embedded (hereinafter referred to as deteriorated toner) and an image is formed, the image quality may be lowered, particularly the image density may be insufficient.

  An object of the present invention is to provide an image forming apparatus capable of suppressing a decrease in image quality due to deteriorated toner.

The image forming apparatus according to claim 1 comprises:
An image holding body for forming a latent image and developing the toner to hold the toner image;
A latent image forming unit that forms a latent image based on image data on the image carrier;
A developing device for developing the latent image formed on the image carrier with toner;
A transfer device for transferring the toner image held on the image carrier onto a recording medium;
A fixing device for fixing the toner image transferred onto the recording medium onto the recording medium;
Monitoring means for monitoring toner consumption per unit operating time of the developing unit;
And a discharging unit that discharges the toner in the developing device onto a recording medium when a toner consumption amount less than a threshold is detected by the monitoring unit.

The image forming apparatus according to claim 2 comprises:
The monitoring means includes a toner per unit operating time of the developing device based on an operating time of the developing device and a toner consumption amount calculated from image data that is a source of latent image formation by the latent image forming unit. It is characterized by calculating consumption.

An image forming apparatus according to claim 3 is provided.
A toner container that contains toner;
Toner supply means for supplying the toner in the toner container to the developer according to consumption of the toner in the developer,
The monitoring means calculates a toner consumption amount per unit operating time of the developing device based on an operating time of the developing device and a toner supply amount to the developing device by the toner supplying means. It is characterized by.

An image forming apparatus according to claim 4 is provided.
4. The image forming apparatus according to claim 1, wherein the discharge unit outputs a solid image on a recording medium.

The image forming apparatus according to claim 5
It has a selection means for selecting whether or not to operate the discharge means when a toner consumption amount less than a threshold is detected by the monitoring means.

An image forming apparatus according to claim 6 is provided.
At least the part including the developing unit is configured as a detachable replacement part,
The monitoring means is characterized in that a new replacement part is mounted and operates after the operating time of a developing device constituting the newly mounted replacement part reaches a threshold time.

The image forming apparatus according to claim 7 comprises:
And a toner collecting means for collecting the toner remaining on the image holding member after the toner image is transferred from the image holding member to the recording medium by the developing unit and feeding the toner to the developing unit.

  According to the image forming apparatus of the first aspect, it is possible to provide an image forming apparatus capable of suppressing a decrease in image quality due to deteriorated toner.

  According to the image forming apparatus of the second aspect, it is possible to calculate the toner consumption amount per unit operation time of the developing device without using a dedicated detection device.

  According to the image forming apparatus of the third aspect, the toner consumption amount per unit operation time of the developing device can be calculated without using a dedicated detection device.

  According to the image forming apparatus of the fourth aspect, it is possible to discharge the deteriorated toner without providing a dedicated deteriorated toner discharging means.

  According to the image forming apparatus of the fifth aspect, it is not possible to eliminate the deteriorated toner contrary to the operator's will.

  According to the image forming apparatus of the sixth aspect, it is possible to prevent erroneous determination of toner deterioration at an initial stage where the toner in the developing device is not deteriorated.

  According to the image forming apparatus of the seventh aspect, it is possible to eliminate the deteriorated toner while preventing waste of the toner.

  Hereinafter, embodiments of the image forming apparatus of the present invention will be described.

  FIG. 1 is a schematic configuration diagram of a copying machine which is an embodiment of an image forming apparatus of the present invention. FIG. 2 is an enlarged view around the photosensitive roller of FIG.

  The configuration will be described with reference to FIGS.

  A copying machine 1 shown in FIG. 1 is a monochrome copying machine and forms a monochrome image on a recording sheet constituting an example of a recording medium. As shown in FIG. 1, an image reading unit 1A on which a copy document is set and an operation unit (not shown) are provided at the top of the copying machine 1, and the copy document is set in the image reading unit 1A. Thereafter, when a copy instruction button in an operation unit (not shown) is operated, the recording is performed and the recording sheet on which the same image as the copy original is formed is discharged from the discharge unit 1B. Although the details will be described later, the operation unit (not shown) is provided with a touch panel type display panel, on which an operation button and information necessary for the operation are displayed. An automatic paper feeder called ADF (Auto Document Feeder) that automatically sets a copy document on the image reading unit 1A is provided at the top of the copying machine.

  As shown in FIG. 1, the copying machine 1 is provided with a sheet feeding unit 1C that separates and feeds a plurality of stacked recording sheets one by one to the transport path P. An image is formed on each recording sheet fed from the section 1C to the conveyance path P, and the recording sheet on which the image is formed is discharged from the discharge section 1B.

  Inside the copying machine 1, a latent image is formed and developed with toner to hold a toner image, a photosensitive roller 10 that charges the photosensitive roller 10, and a photosensitive roller 10 on the photosensitive roller 10. A latent image forming unit 12 that forms a latent image based on image data, a developing unit 13 that develops the latent image formed on the photosensitive roller 10 with toner, and a toner image held on the photosensitive roller 10 is recorded on a recording sheet. A transfer roller 14 for transferring the toner image onto the recording paper and a pair of fixing heating rollers 15 for fixing the toner image transferred onto the recording paper on the recording paper. A toner container 16 is provided. In the present embodiment, the photosensitive roller 10 constitutes an example of an image carrier.

  The configuration around the photosensitive roller 10 will be described in detail with reference to FIG.

  A charging roller 11, a developing roller 13, and a transfer roller 14 that rotate in synchronization with the photosensitive roller 10 are disposed around the photosensitive roller 10 that rotates in the direction of arrow A. Further, a latent image forming unit 12 is disposed between the charging roller 11 and the developing roller 13.

  First, after the photosensitive roller 10 is charged by the charging roller 11, a latent image is formed on the charged photosensitive roller 10 by the latent image forming unit 12. In the latent image forming unit 12, a plurality of laser diodes are arranged in the main scanning direction (direction perpendicular to the paper surface of FIG. 2) so that a latent image can be formed on the photosensitive roller 10 in dot units. These laser diodes form a latent image on the photosensitive roller 10 in dot units. An instruction is given to the plurality of laser diodes provided in the latent image forming unit 12 according to the image data from the control unit 1D, and the respective lighting timings of the laser diodes are adjusted to rotate the latent image according to the image data. Formed on the photosensitive roller 10. Although details will be described later, it is possible to calculate the amount of toner by summing all the laser diodes for how many dots each of the laser diodes are lit to form a latent image for one image. .

  The latent image is developed with the supply of toner from the developing device 13, and the toner image is transferred onto the recording paper by the transfer roller 14. Thereafter, the recording paper is conveyed to the fixing device 15 where the image is fixed on the recording paper.

  On the other hand, the toner remaining on the photosensitive roller 10 after the transfer is scraped out by the scraping member 151 whose tip contacts the photosensitive roller 10. The scraped toner is stacked on the tip of the scraping member 151, and the stacked toner is collected by the rotation of a cylindrical member 152 having a spiral groove cut on the outer surface. Further, the toner conveyed along the groove of the cylindrical member 152 is collected by the developing device 13 through the pipe 153 and mixed with unused toner for use. In the present embodiment, the scraping member 151, the cylindrical member 152 having a spiral groove cut on the surface, and the pipe 153 constitute an example of the toner collecting means referred to in the present invention. In FIG. 2, the respective toner transport paths are indicated by a dotted line and a two-dot chain line so that the transport path of the reused toner and the transport path of the new toner supplied from the toner container can be seen. Has been.

  Here, the configuration of the developing device 13 will be described in detail with reference to FIG.

  Here, the developing device 13 shown in FIG. 2 receives the toner supplied from the toner container 16 by the operation of a dispense motor (not shown) on the back side of FIG. 2 and spirals in the direction toward the surface of FIG. Agitating / conveying path 131 that conveys in a groove, and the toner conveyed by the agitating / conveying path 131 is received on the front surface side of FIG. 2 and is conveyed in a spiral groove in the direction from the front surface to the back surface of FIG. And a developing roller 133 that receives the toner that has been transported through the other stirring and transporting path 132.

  A carrier made of a magnetic material is placed in the agitation transport paths 131 and 132, and toner is transported while being electrostatically coupled around the carrier. At this time, the toner is charged by receiving frictional force by stirring, and the charged toner and carrier are transported to the developing roller 133 through the stirring transport paths 131 and 132. When the charged toner and the magnetic carrier are conveyed to the developing roller 133, the carrier is attracted to the surface of the cylindrical sleeve rotating around the magnet under the magnetic force of the magnet inside the developing roller 133. Toner is attracted along with the carrier. The toner charged by the rotation of the cylindrical sleeve and the rotation of the photosensitive roller 10 adheres in accordance with the potential distribution of the latent image on the photosensitive roller 10 to develop the latent image. The carrier on the developing roller 153 remains on the developing roller 153 even after developing with toner, and is returned to the agitating and conveying units 131 and 132 by further rotation of the developing roller 153.

  Then, the toner image is transferred by the transfer roller 14 to the recording sheet fed and conveyed from the sheet feeding unit 1C (see FIG. 1) to the conveyance path P, and the toner image is heated and pressed by the pair of heating rollers 15. After being fixed on the recording sheet, the recording sheet on which the toner image is fixed is discharged from the discharge unit 1B (see FIG. 1). In FIG. 2, the conveyance path P is indicated by a one-dot chain line.

  In this example, the photosensitive roller 10, the charging roller 11, the latent image forming unit 12, the developing device 13, the scraping member 151 that constitutes an example of the toner collecting means according to the present invention, and a spiral groove on the outer surface. The cut cylindrical member 152 and the pipe 153 are accommodated in one cartridge, and the cartridge can be replaced when the photosensitive roller 10 is worn. This cartridge constitutes an example of the replacement part referred to in the present invention.

  Here, a state in which deteriorated toner increases in the copying machine of FIG. 1 will be described.

  FIG. 3 is a diagram for explaining a state in which the toner consumption is small and the deteriorated toner is expected to increase for a long operation time in the developing device 13.

  In the copying machine 1 of FIG. 1, the developing roller 131, the agitation transport paths 131 and 132, the photosensitive roller 10, the transfer roller 14, and the heating roller 15 provided in the developing unit 13 are all driven by one motor. Yes. For this reason, the developing unit 13 continues to operate during the process. A pair of heating rollers 15 constituting an example of the fixing device 15 is provided with a temperature sensor at the center.

  As shown in FIG. 3A, when copying on an A4 size recording paper is repeatedly performed at a speed of 18 PPM (Print Per Minute), the copying machine shown in FIG. 1 forms on the recording paper. As long as the image to be printed is an image with a normal level of toner consumption, printing in a stable state is performed.

  However, when printing on a postcard as shown in FIG. 3C at the same speed (18 PPM) as printing on this A4 size recording paper, the transfer is performed only at the center of the heating roller 15, and thus heating is performed. Only the temperature at the center of the roller is lowered.

  As described above, since the temperature sensor is provided in the central portion of the heating roller 15, the controller 1 </ b> D continues to pass a current to a heater (not shown) inside the heating roller 15 in the above state. The temperature will continue to rise. For this reason, the temperature of the heating roller 15 may rise more than necessary.

  Therefore, in the copying machine 1 shown in FIG. 1, when printing on a postcard is repeatedly performed, the control unit increases the time interval of repeated printing as shown in FIG. Control is performed to keep the temperature drop at the center of the roller 15 to a minimum. For this reason, when printing on a postcard is repeated, the time during which the developing device 13 rotates idly during the printing process (that is, the time during which the same toner passes through the agitation transport paths 131 and 132) becomes longer. The toner is easily subjected to a great stress due to agitation and becomes a deteriorated toner.

  The above example is an example in which the developing device 13 rotates idly. However, the developing device 13 is not only a problem of the print interval, but also when the image having a very large white area is repeatedly formed on the recording medium as described above. As the operation time of 13 is longer, the amount of toner consumption decreases, and deteriorated toner is likely to be generated.

  Therefore, in the present embodiment, when a mode called a density recovery mode is provided and the mode is set by the user, the control unit 1D instructs the latent image forming unit 12 to form an all black latent image, thereby developing the developer. 13 is discharged onto a recording sheet so that the deteriorated toner can be removed outside the copying machine.

  FIG. 4 is a flowchart for explaining the transition process to the density recovery mode executed by the control unit 1D. FIG. 5 is a diagram showing a message displayed on the display panel 10A of the operation unit when the control unit 1D is executing a process according to the flowchart. As described above, the display panel 10A in FIG. 5 is provided on the upper portion of the copying machine 1 in FIG. 1, and the display panel is configured by a touch panel.

  In response to an operation of a print instruction button (not shown) displayed on the touch panel in FIG. 5, the control unit 1 </ b> D executes the process of this flow. Since the normal print process is performed after the process of the flow of FIG. 4 is completed, the word “normal print operation” is written in the flow of FIG. 4 instead of the word “end”.

  The flow of FIG. 4 will be described.

  In step S401, it is determined whether the operation time after cartridge replacement is less than the threshold “A”. If it is determined Yes in step S401, it is determined that the toner in the developing device 13 is new and there is no deteriorated toner, and the processing of this flow is terminated without doing anything.

  If NO is determined in step S401, the process proceeds to step S402, and in step S402, the toner consumption calculated from the operation time of the developing device 13 after the cartridge replacement and the image data from which the latent image forming unit 12 forms the latent image is obtained. Based on the amount, the toner consumption per unit operating time of the developing device 13 is calculated.

  In this flow, as the toner consumption calculated from the image data that is the basis of the latent image formation by the latent image forming unit 12, the number of times that the diodes are turned on according to the image data is counted for all the diodes as described above. Using the dot count number, it is determined whether or not the value obtained by dividing the dot count number by the operating time of the developing device 13 is less than the threshold value B. Here, when it is determined that the value is equal to or greater than the threshold value B, it is determined that the toner consumption is large and the amount of deteriorated toner is small, the process proceeds to No and the process of this flow is terminated.

  If it is determined in step S402 that the toner consumption is less than the threshold value B, the operation time of the developing device is long and it is predicted that the deteriorated toner in the developing device 13 is increasing while the toner consumption is small. In step S403, it is determined whether automatic execution of the density recovery mode is set to on or off. If it is determined in step S403 that the density recovery mode is set to on, the process proceeds to step S404, where the density recovery mode is executed and the latent image forming unit 12 is instructed to form an all black latent image on the photosensitive roller 10. Then, all the toner in the developing device 13 is attached to the photosensitive roller 10 and transferred onto the recording paper, whereby the deteriorated toner is discharged onto the recording paper. At this time, the display panel 10A displays that the density recovery mode is being executed, and notifies the user that the discharged recording paper is in the density recovery mode.

  On the other hand, if it is determined in step S403 that the density recovery mode is set to off, the process proceeds to the off side, and in step S405, the density is displayed on the display panel with the message 'We recommend that you manually execute the density recovery mode'. Two operation buttons, a recovery mode execution button 100A and a normal button 101A, are displayed (see FIG. 5).

  In step S406, it is determined which one of the density recovery mode button 100A and the normal button 101A has been designated. If it is determined that “normal” has been designated, the process of this flow is terminated, and the density recovery mode is completed. Is determined, the process proceeds to step S404, and in step S404, the latent image forming unit 12 is instructed to form an all black latent image on the photosensitive roller 10, and all the toner in the developing device 13 is discharged to the photosensitive member. The deteriorated toner is discharged onto the recording paper by being attached to the roller 10 and transferred onto the recording paper, and the processing of this flow is completed.

  When the control unit 1D executes the flow of FIG. 4, the deteriorated toner can be eliminated by discharging the deteriorated toner onto the recording sheet and discharging the recording sheet outside the copying machine.

  Further, when the developing device 13 is an exchange member as in this embodiment, the processing in step S401 in the flow of FIG. 4 prevents erroneous determination of toner deterioration at the initial stage where the toner in the developing device has not deteriorated. The effect that it is done is pulled out.

  In the embodiment shown in FIG. 1 to FIG. 5 described above, an example of the monitoring means according to the present invention is configured by the control unit 1D, and the control unit 1D, the photosensitive roller 10, the latent image forming unit 12, the transfer roller 14, and the like. Thus, an example of the discharging means according to the present invention is configured. In the present embodiment, the control unit 1D and the display panel 10A constitute an example of an inquiry unit and an example of an instruction receiving unit.

  FIG. 6 is a diagram for explaining the second embodiment.

  As shown in FIG. 6, the amount of toner consumption can also be detected by detecting the amount of toner supplied to the developing device 13 from the toner storage container 16 in which the toner is stored.

  Therefore, in the flow of FIG. 6, instead of step S402 of FIG. 3, based on the operating time of the developing device 13 and the toner supply amount to the developing device 13 by the toner supply means, Step S402A for calculating the toner consumption is changed.

  In the copying machine of FIG. 1, the amount of toner supplied from the toner container 16 to the developing device 13 is controlled by a dispense motor (not shown). Therefore, in the example of FIG. 6, the control unit 10 calculates the toner supply amount using the drive time of the dispense motor.

  Note that a sensor capable of detecting the mixing ratio of the carrier and the toner is provided in the stirring running paths 131 and 132 provided in the developing device 13, and the control unit 10 is not illustrated based on the detection result of the sensor. The dispense motor is driven to supply toner from the toner container 16 to the developing device 13.

  Therefore, even in the flow of FIG. 6, the control unit 10 calculates the toner consumption amount in the same manner as in FIG. 4, inquires the user in step S <b> 405, receives an instruction from the user in step S <b> 406, and density in step S <b> 404. The recovery mode can be executed, and after the density recovery mode is set, it is possible to immediately jump to step S404 and execute the density recovery mode without waiting for the user's instruction.

  In this embodiment, a monochrome copying machine has been described as an example of the image forming apparatus according to the present invention. However, the image forming apparatus according to the present invention is also applied to a color copying machine.

  The image forming apparatus referred to in the present invention may be a printer or a facsimile as long as it is an electrophotographic image forming apparatus.

  Furthermore, in this embodiment, as an example of the image forming apparatus according to the present invention, a direct transfer type copying machine that directly transfers a toner image on a photosensitive roller onto a conveyed recording sheet using a transfer roller is given. As described above, the image forming apparatus according to the present invention may be an indirect transfer type image forming apparatus that transfers a developing device to a recording sheet via a transfer belt.

  Further, in the present embodiment, as the image carrier referred to in the present invention, a photoconductor roller adopting a roller method has been described as an example. However, the image carrier referred to in the present invention is a photoconductor employing a circulation belt method. It may be a belt.

  In this embodiment, as the cartridge, the photosensitive roller 10, the charging roller 11, the latent image forming unit 12, the developing device 13, and the scraping member 151 that constitutes an example of the toner collecting unit according to the present invention and the outer surface. The cartridge in which the cylindrical member 152 and the pipe 153 in which a spiral groove is cut is described as an example, but it is sufficient that the cartridge is provided with at least a developing device.

  In this embodiment, an example in which the fixing device and the transfer roller have different configurations has been described, but a configuration in which transfer and fixing are performed simultaneously may be used.

  Furthermore, in this embodiment, a copying machine configured to collect and reuse toner is described as an example. However, a configuration in which toner is collected and collected in a collection box without being reused may be used. .

1 is a schematic configuration diagram of a copying machine which is an embodiment of an image forming apparatus of the present invention. FIG. 3 is an enlarged view around a photoreceptor. FIG. 6 is a diagram for explaining a state in which toner consumption is small and deteriorated toner is expected to increase for a long operation time in the developing device. It is a flowchart explaining the transfer process to the density | concentration recovery mode which control part 1D performs. It is a figure which shows the message displayed on 10 A of display panels of an operation part, when control part 1D is performing the process according to the procedure of the flowchart. It is a figure explaining 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Copier 1A Image reading part 1B Paper feed part 1C Ejection part 1D Control part 10 Photosensitive roller 11 Charging roller 12 Latent image formation part 13 Developer 14 Transfer roller 15 Heating roller 16 Toner container P Paper conveyance part

Claims (7)

An image holding body for forming a latent image and developing the toner to hold the toner image;
A latent image forming unit that forms a latent image based on image data on the image carrier;
A developing device for developing the latent image formed on the image carrier with toner;
A transfer device for transferring the toner image held on the image carrier onto a recording medium;
A fixing device for fixing the toner image transferred onto the recording medium onto the recording medium;
Monitoring means for monitoring toner consumption per unit operating time of the developing unit;
An image forming apparatus comprising: a discharge unit configured to discharge the toner in the developing unit onto a recording medium when a toner consumption amount less than a threshold is detected by the monitoring unit.   The monitoring unit is configured to determine a toner per unit operating time of the developing device based on an operating time of the developing device and a toner consumption amount calculated from image data that is a source of latent image formation by the latent image forming unit. The image forming apparatus according to claim 1, wherein the consumption amount is calculated. A toner container that contains toner;
Toner supply means for supplying the toner in the toner container to the developer according to consumption of the toner in the developer;
The monitoring means calculates a toner consumption amount per unit operating time of the developing device based on an operating time of the developing device and a toner supply amount to the developing device by the toner supplying means. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 1, wherein the discharge unit outputs a solid image on a recording medium.   5. The apparatus according to claim 1, further comprising a selection unit configured to select whether to operate the discharge unit when a toner consumption amount less than a threshold is detected by the monitoring unit. Image forming apparatus. At least the part including the developing device is configured as a detachable replacement part,
6. The monitoring unit operates after the operating time of a developing device constituting the newly mounted replacement part is reached after a new replacement part is mounted and reaches a threshold time. The image forming apparatus according to claim 1.   And a toner recycling unit that collects toner remaining on the image carrier after the toner image is transferred from the image carrier to the recording medium by the transfer unit, and sends the toner to the developing unit for reuse. The image forming apparatus according to any one of claims 1 to 6.

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