JP7471945B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus. In particular, it relates to an electrophotographic image forming apparatus that forms an image on a recording material using an electrophotographic method.

Conventionally, there are configurations in which a process cartridge can be detachably attached to the main body of an image forming device. In addition, some process cartridges are equipped with a waste toner box that collects and stores "residual toner" that remains on the photosensitive drum after transfer and "fog toner" that exists in non-image areas.

On the other hand, in recent years, there has been a demand for smaller, larger capacity process cartridges, and efforts are being made to reduce the waste toner box (volume) of process cartridges (see Patent Documents 1 and 2).

Specifically, in Patent Document 1, an alumina layer with a higher volume resistivity than a rubber layer is provided on the surface of the developing roller, thereby reducing the generation of "fog toner" and, as a result, reducing the capacity of the waste toner box of the process cartridge.

In addition, in Patent Document 2, the developer and development process conditions are optimized to reduce the amount of waste toner such as "residual toner after transfer" and "fog toner," thereby reducing the capacity of the waste toner box of the process cartridge.

Patent Publication 2015-94897 JP2001-343779

However, there is still room for improvement in the configurations of Patent Documents 1 and 2. Specifically, for example, when a paper jam occurs in a printer (hereinafter referred to as a "jam"), a large amount of "(jammed) toner" that is not transferred to the paper and is transferred to the photosensitive drum, etc., is also collected and stored in the waste toner box of the process cartridge. For this reason, in Patent Documents 1 and 2, it was necessary to maintain a certain amount of capacity in the waste toner box of the process cartridge in advance in preparation for dealing with unexpected cases such as a "jam" (jam clearance). Therefore, it cannot be said that the waste toner box provided in the process cartridge has yet been sufficiently miniaturized.

In view of the above problems, the present invention aims to provide an image forming device that can effectively handle jamming while minimizing the capacity of the recovery developer box provided in the cartridge.

The image forming apparatus of the present invention comprises:
a rotatable image carrier that carries on its surface a developer image developed from an electrostatic latent image;
a developer carrier that carries a developer to be supplied to the image carrier in order to develop the electrostatic latent image and is capable of contacting the image carrier;
an exposure member for irradiating and exposing the surface of the image carrier;
an intermediate transfer member that is in contact with a surface of the image carrier and that carries the developer image transferred from the image carrier and is rotatable;
a cleaning member for cleaning the surface of the intermediate transfer body;
a secondary transfer member for secondarily transferring the developer image from the intermediate transfer body to a recording medium on which the developer image is to be recorded;
a fixing member that fixes the developer image transferred onto the recording medium by the secondary transfer member;
A detection member for detecting a conveyance state of the recording medium;
A control unit;
An image forming apparatus comprising:
The control unit is
a first operation of continuing the rotational operations of the image carrier and the intermediate transfer body without stopping the rotational operations when the detection member detects that the conveyance state of the recording medium is defective;
a second operation of stopping the rotation of the image carrier when the surface of the image carrier moves a predetermined distance by the rotation of the image carrier after the defect is detected;
In the first operation,
The fixing operation of the fixing member is stopped,
The predetermined distance is
a length of the surface of the image carrier from a development position in contact with the developer carrier to a transfer position in contact with the intermediate transfer body in a rotation direction of the image carrier, or longer;
It is also characterized in that the distance is less than or equal to the distance traveled by the surface of the image carrier during the period in which the recording medium moves from the secondary transfer position on the secondary transfer member to the fixing position on the fixing member.

The image forming device of the present invention can effectively handle jamming while minimizing the capacity of the recovery developer box provided in the cartridge.

1 is a schematic cross-sectional view of an image forming apparatus according to a first embodiment of the present invention; FIG. 1 is a control block diagram of an image forming apparatus according to a first embodiment of the present invention. (a) is a schematic cross-sectional view of a process cartridge used in an image forming apparatus according to a first embodiment of the present invention; (b) is a schematic diagram showing a contact position and a separation position in the process cartridge; (c) is a schematic diagram showing a predetermined distance L; (d) is a schematic diagram showing a maximum value of the predetermined distance L. Flowchart regarding control when a jam occurs in the image forming apparatus according to the first embodiment of the present invention 1A and 1B are schematic diagrams illustrating the transfer state of developer in an image forming apparatus according to a first embodiment of the present invention and a comparative example; Flowchart for control during jamming (clearance) in an image forming apparatus according to a second embodiment of the present invention 1A and 1B are schematic diagrams showing the transfer state of developer in an image forming apparatus according to a second embodiment of the present invention and a reference example (first embodiment); Flowchart regarding control when a jam occurs in an image forming apparatus according to a third embodiment of the present invention

The electrophotographic image forming apparatus according to the present invention will be described below with reference to the drawings. Note that the embodiment described below is merely an example of the present invention, and the dimensions, materials, shapes, and relative positions of the components described below do not limit the scope of the present invention unless otherwise specified.

Here, an electrophotographic image forming apparatus is one that forms an image on a recording medium using an electrophotographic image forming method. Examples of electrophotographic image forming apparatuses include electrophotographic copying machines, electrophotographic printers (e.g., laser beam printers, LED printers, etc.), facsimile machines, and word processors.

A process cartridge that constitutes part of an image forming apparatus is a cartridge that integrates a charging means, a developing means or a cleaning means with an electrophotographic photosensitive drum, and is detachably attached to the main body of an electrophotographic image forming apparatus. A process cartridge that integrates at least one of a charging means, a developing means or a cleaning means with an electrophotographic photosensitive drum, and is detachably attached to the main body of an electrophotographic image forming apparatus. A process cartridge that integrates at least a developing means and an electrophotographic photosensitive drum with an electrophotographic image forming apparatus, and is detachably attached to the main body of an electrophotographic image forming apparatus.

The following describes the configuration of an electrophotographic image forming apparatus (hereinafter, image forming apparatus) and the image forming process according to an embodiment of the present invention (hereinafter, this embodiment) with reference to the drawings.

The following describes the overall configuration of the image forming apparatus, the configuration of the process cartridge, and the configuration that characterizes the invention in the first embodiment of the present invention, using Figures 1 to 5.

[Overall Configuration of Image Forming Apparatus]
Hereinafter, the overall configuration of one embodiment of an electrophotographic image forming apparatus (image forming apparatus) of the present invention will be described.

Figure 1 is a schematic cross-sectional view of an image forming apparatus according to a first embodiment of the present invention.

As shown in FIG. 1, the image forming apparatus 100 of the present invention is a full-color laser beam printer that employs an intermediate transfer method. The image forming apparatus 100 can form a full-color image on a recording material 35 (e.g., recording paper, a plastic sheet, cloth, etc.) using toner (developer) 80 according to image information. The image information is input to the image forming apparatus main body from an image reading device connected to the image forming apparatus main body 100A, or from a host device such as a personal computer connected to the image forming apparatus main body so as to be able to communicate with the image forming apparatus main body.

The image forming device 100 has multiple image forming units, each of which has process cartridges 7 SY, SM, SC, and SK for forming images in the colors yellow (Y), magenta (M), cyan (C), and black (K).

The process cartridge 7 is detachably attached to the image forming device 100 via attachment means such as an attachment guide and a positioning member provided on the image forming device main body. In this embodiment, the process cartridges 7 for each color all have the same shape, and the process cartridges 7 for each color contain toner (developer) 80 of the respective colors: yellow (Y), magenta (M), cyan (C), and black (K).

Around the photosensitive drum 1 (image carrier), an exposure device 30 (exposure member) consisting of a scanner unit is arranged. The exposure device 30 irradiates a laser based on image information to form an electrostatic image (electrostatic latent image T0) on the photosensitive drum 1. In the main scanning direction (direction perpendicular to the sheet material transport direction), the laser exposure is started for each scanning line from a position signal in a polygon scanner called BD. On the other hand, in the sub-scanning direction (sheet material transport direction), it is delayed by a predetermined time from a TOP signal that starts from a switch (not shown) in the sheet material transport path. This allows laser exposure to always be performed at the same position (exposure position Y1) on the photosensitive drum 1 in the four process stations Y, M, C, and Bk.

Facing the four photosensitive drums 1, an intermediate transfer belt 31 is disposed as an intermediate transfer body for transferring the toner image (developer image T1) on the photosensitive drum 1 to a recording material 35. The intermediate transfer belt 31, which is formed of an endless belt as an intermediate transfer body, contacts all the photosensitive drums 1 and moves (rotates) in a circular motion in the direction of the arrow B (counterclockwise) shown in the figure. The contact position between the photosensitive drums 1 and the intermediate transfer belt 31 is the transfer position Y2 described later.

Four primary transfer rollers 32 are arranged side by side on the inner peripheral surface of the intermediate transfer belt 31, facing the photosensitive drums 1 (a-d), as primary transfer means. A bias of the opposite polarity to the normal charging polarity of the toner is applied to the primary transfer rollers 32 from a primary transfer bias power supply (high voltage power supply) as primary transfer bias application means (not shown). As a result, the toner image on the photosensitive drum 1 is transferred (primary transfer) onto the outer peripheral surface 31a of the intermediate transfer belt 31 (intermediate transfer body) at the transfer position Y2.

A secondary transfer roller 33 is disposed on the outer peripheral surface side of the intermediate transfer belt 31 as a secondary transfer means. A bias of the opposite polarity to the normal charging polarity of the toner is applied to the secondary transfer roller 33 from a secondary transfer bias power supply (high voltage power supply) as a secondary transfer bias application means (not shown). This causes the toner image on the intermediate transfer belt 31 to be transferred (secondary transfer) to the recording material 35. For example, when a full-color image is formed, the above-mentioned process is performed sequentially in the image forming units SY, SM, SC, and SK, and the toner images of each color are sequentially superimposed and primarily transferred onto the intermediate transfer belt 31.

The image forming apparatus 100 is equipped with a pickup roller 144, a transport roller 148, and a registration roller 160 as transport means for transporting the recording material 35 to the secondary transfer section. The recording material 35 is fed by the pickup roller 144 at a predetermined timing from the start of exposure. It is then transported by the transport roller 148 and the registration roller 160, and when the leading edge of the recording material 35 is detected by the paper detection sensor 161, the transport roller 148 and the registration roller 160 are temporarily stopped and put into a standby state. Then, at a predetermined timing, the drive of the transport roller 148 and the registration roller 160 is resumed. Then, the recording material 35 in the standby state starts to move and is transported toward the secondary transfer section. The paper detection sensor 161 is connected to a "detection member D" described later, and can output a signal to the detection member D.

By feeding and re-feeding paper at a predetermined timing from the start of exposure, the toner image on the intermediate transfer belt 31 is perfectly overlapped with the recording material 35 at the secondary transfer section, and the toner image is secondary transferred onto the recording material 35 without misalignment.

The recording material 35 onto which the toner image has been transferred is transported to a fixing device (fixing member) 34, which serves as a fixing means. The fixing device 34 applies heat and pressure to the recording material 35, thereby fixing the toner image to the recording material 35.

After the secondary transfer, residual toner remaining on the intermediate transfer belt 31 is collected by the intermediate transfer belt cleaning member 11A and stored in the collected toner box 11B (collected developer box).

[Control system of image forming apparatus]
Next, a control system of the image forming apparatus will be described.

Figure 2 is a control block diagram of an image forming apparatus according to the first embodiment of the present invention.

As shown in FIG. 2, all processing of the image forming apparatus is centrally controlled by a system controller 901. The system controller 901 (controller) is mainly responsible for driving each load in the image forming apparatus, collecting and analyzing information from sensors, and exchanging data with the display unit 906, i.e., the user interface. The system controller 901 is equipped with a CPU 903 to perform these functions. The CPU 903 executes various sequences related to predetermined image formation according to a program stored in a ROM 904 also installed in the system controller 901. In this case, a RAM 905 is also installed to store data that needs to be stored temporarily or permanently. The RAM 905 stores the high voltage setting value for the high voltage controller 908, various data, image formation command information from the display unit 906, and the like.

The system controller 901 obtains information such as printing conditions and density settings set by the user from the display unit 906. On the other hand, the system controller 901 sends data to the display unit 906 to show the user the status of the image forming device, such as the number of images formed and whether or not image formation is in progress, the occurrence and location of a jam, etc.

This image forming device has multiple motors, DC loads such as clutches/solenoids, and sensors such as photointerrupters located in various places inside the device. In other words, the motors and DC loads are driven appropriately to transport the recording medium and drive each unit, and these operations are monitored by various sensors.

The system controller 901 detects signals from various sensors using a sensor input unit 911, and controls the stopping and driving of each motor using a motor control unit 909 based on the signals. 909 also controls the contact and separation operation between the intermediate transfer belt 31 and the photosensitive drum, and between the developing roller and the photosensitive drum.

At the same time, the DC load control unit 910 operates the clutch/solenoid to ensure smooth image formation. In addition, by sending various high-voltage control signals to the high-voltage control unit 908, appropriate high voltages are applied to the charging roller, developing roller, primary transfer roller, secondary transfer roller, etc., which make up the high-voltage unit 914.

The fixing device 34 also includes a built-in fixing heater 915 as a heating element, which is turned on and off by an AC driver 912. The fixing heater 915 is also provided with a thermistor 913 as a temperature detector for measuring its temperature. The resistance change of the thermistor 913, which corresponds to the temperature change of the fixing heater, is converted into a voltage value by an A/D converter 907, and then input to the system controller 901 as a digital value. The aforementioned AC driver 912 is controlled based on this temperature data.

[Process Cartridge Configuration]
Next, the overall structure of the process cartridge 7 that is mounted in the image forming apparatus 100 of this embodiment will be described with reference to FIG.

Fig. 3(a) is a cross-sectional conceptual diagram of a process cartridge used in an image forming apparatus according to the first embodiment of the present invention, Fig. 3(b) is a conceptual diagram showing the contact position and the separation position in the process cartridge, Fig. 3(c) is a schematic diagram showing the predetermined distance L, and Fig. 3(d) is a schematic diagram showing the maximum value of the predetermined distance L. In this embodiment, the configuration and operation of the process cartridges 7 for each color are substantially the same, except for the type (color) of toner contained therein.

Figure 3(a) shows the process cartridge 7 as seen along the longitudinal direction (rotation axis direction) of the photosensitive drum 1. Note that the process cartridge 7 shown in Figure 3(a) is in the position when it is attached to the main body of the image forming apparatus. In the following, when describing the positional relationships and directions of the various components of the process cartridge, the positional relationships and directions are referred to in the position shown in Figure 3.

In this embodiment, the process cartridge 7 is configured by integrating a photosensitive unit 13 equipped with a photosensitive drum 1 (image carrier) and the like, and a developing unit 4 equipped with a developing roller 17 (developer carrier) and the like.

The photoconductor unit 13 has a cleaning frame (first frame) 13a as a frame that supports various elements within the photoconductor unit 13. The photoconductor drum 1 is rotatably attached to the cleaning frame 13a via a bearing (not shown). The photoconductor drum 1 is driven to rotate in the direction of the arrow A (clockwise) in response to the image formation operation by the driving force of a driving motor (not shown) serving as a driving means (driving source) being transmitted to the photoconductor unit 13.

In this embodiment, the photoconductor drum 1, which is the center of the image formation process, is an (organic) photoconductor drum 1 in which the outer surface of an aluminum cylinder is coated with a functional film, an undercoat layer, a carrier generation layer, and a carrier transport layer, in that order.

In addition, the photosensitive unit 13 is provided with a cleaning member 6 (second cleaning member) and a charging roller 2 so as to come into contact with the peripheral surface of the photosensitive drum 1. Residual toner removed from the surface of the photosensitive drum 1 by the cleaning member 6 falls into and is stored in a recovered toner box (recovered developer chamber) 14 formed inside the cleaning frame 13a.

The charging roller 2, which serves as the charging means, rotates by pressing the conductive rubber roller part against the photosensitive drum 1.

Here, a predetermined DC voltage is applied to the core of the charging roller 2 relative to the photosensitive drum 1 as a charging process, and a uniform dark area potential (Vd) is formed on the surface of the photosensitive drum 1. The spot pattern of laser light emitted from the exposure device 30 described above in response to image data exposes the photosensitive drum 1, and the exposed areas lose surface charge due to carriers from the carrier generation layer, lowering the potential. As a result, an electrostatic latent image is formed on the photosensitive drum 1, with the exposed areas at a predetermined bright area potential (Vl) and the unexposed areas at a predetermined dark area potential (Vd). In this embodiment, Vd = -500V, Vl = -100V.

The developing unit 4, on the other hand, has a frame (second frame) 4a, and has a developing chamber 18a in which a developing roller 17 as a developer carrier for carrying toner 80 and a toner supply roller 20 as a supply member for supplying toner to the developing roller 17 are disposed. Furthermore, the frame (second frame) 4a of the developing unit 4 has a toner storage chamber (developer storage chamber) 18b for storing toner, and the toner storage chamber 18b is located lower in the direction of gravity than the toner supply roller 20. The developing chamber 18a and the toner storage chamber 18b are formed by dividing the internal space of the frame 4a by a partition 18c, but are connected by an opening 18d.

The toner supply roller 20 also rotates, forming a toner nip N (the area where the toner is sandwiched between the developing roller 17 and the toner supply roller 20) between the developing roller 17 and the toner supply roller 20.

A stirring and transporting member 22 is provided in the toner storage chamber 18c. The stirring and transporting member 22 stirs the toner stored in the toner storage chamber 18c and also transports the toner in the direction of the arrow G in the figure toward the top of the toner supply roller 20.

The developing blade 21 is disposed below the developing roller 17 and abuts against the developing roller in a counter manner, regulating the coating amount of the toner supplied by the toner supply roller 20 and imparting an electric charge. In this embodiment, a 0.1 mm thick SUS plate in the shape of a leaf spring is used as the developing blade 21, and the spring elasticity of the plate is used to generate a contact pressure, and its surface abuts against the toner and developing roller 17. The developing blade is not limited to this, and may be a thin metal plate such as phosphor bronze or aluminum. The surface of the developing blade 21 may also be coated with a thin film of polyamide elastomer, urethane rubber, urethane resin, etc.

The toner is charged by friction between the developing blade 21 and the developing roller 17, and the toner layer thickness is regulated at the same time as the charge is given to the toner. In this embodiment, a predetermined voltage is applied to the developing blade 21 from a blade bias power supply (not shown) to stabilize the toner coat. In this embodiment, a blade bias of V = -500 V is applied.

The developing roller 17 and the photosensitive drum 1 each rotate so that their surfaces move in the same direction (from bottom to top in this embodiment) at the opposing portions.

In this embodiment, the developing roller 17 is arranged in contact with the photosensitive drum 1, but the developing roller 17 may be arranged close to the photosensitive drum 1 with a predetermined distance between them.

In this embodiment, toner negatively charged by friction with respect to a predetermined DC bias applied to the developing roller 17 transfers only to the bright potential area due to the potential difference at the developing section (developing position Y3) that contacts the photosensitive drum 1, thereby visualizing the electrostatic latent image. In this embodiment, a potential difference of ΔV = 200 V with the bright potential area is created by applying V = -300 V to the developing roller, forming a toner image.

The toner supply roller 20 is an elastic sponge roller with a foam layer formed on the outer circumference of a conductive core metal. The toner supply roller 20 and the developing roller 17 are in contact with each other with a predetermined penetration amount, that is, the amount of depression ΔE that the toner supply roller 20 is made into a concave shape by the developing roller 17 in FIG. 3. The toner supply roller 20 and the developing roller 17 rotate in opposite directions with a peripheral speed difference at the nip portion N, and this operation allows the toner supply roller 20 to supply to the developing roller 17.

[Action when a jam occurs]
Next, the operation (control) when a jam of the recording medium occurs in this embodiment will be described with reference to FIG.

Figure 4 is a flowchart showing the control when a jam occurs in the image forming apparatus according to the first embodiment of the present invention.

First, the image forming apparatus 100 of this embodiment is equipped with a fixing motor (not shown) that rotates the fixing roller 170 of the fixing device 34, and a belt motor (not shown) that rotates the intermediate transfer belt 31. The image forming apparatus 100 also includes a cartridge drive motor (not shown) that can independently rotate the photosensitive unit and the developing unit in the process cartridge 7.

The system controller 901 (controller) can control the driving and stopping of these motors by sending control signals to the motor controller 909. The system controller 901 also inputs signals output from various sensors, such as the fixing paper discharge sensor 171 and the paper detection sensor 161, to a detection member D via a sensor input unit 911 to detect "feedback (jam)". In other words, the system controller 901 is equipped with a "feedback detection means (detection member D)" that can detect (identify) the location of a jam in the image forming device.

During image formation, the system controller 901 constantly monitors whether a jam has occurred.

As shown in FIG. 4, in this embodiment, in step S1 (jam detection process), when the system controller 901 (detection member D) detects the occurrence of a jam during image formation operation, it proceeds to step S2.

In step S2, the system controller 901 (controller) first stops the exposure operation by the exposure device 30. At the same time, the rotational drive of the process cartridge 7, intermediate transfer belt 31, and secondary transfer roller 33 is not stopped, but continues for a predetermined period of time.

This predetermined (continuous) period corresponds roughly to a distance d1 (d1 = 45 mm in this embodiment) which is equivalent to the predetermined distance L (on the path of movement of the electrostatic latent image/toner image) from the exposure unit (exposure position Y1) to the transfer unit (transfer position Y2). In other words, this predetermined (continuous) period is the time required to move (rotate) the surface of the photosensitive drum the predetermined distance L.

Then, when a predetermined period (predetermined distance L) has elapsed (moved) since the occurrence of the jam was detected, the system controller 901 stops the image forming operation of the image forming device 100 (step S3). Specifically, in step S3, the operations (related to image formation) of the process cartridge 7, intermediate transfer belt 31, and secondary transfer roller 33 included in the image forming device 100 are stopped.

In addition, in step S2, the fixing operation of the fixing device 34 (fixing member) may cause the paper to wrap around the fixing roller, resulting in a so-called "wrap jam." In order to prevent such a problem from occurring, the fixing operation of the fixing device 34 may be stopped in advance in step S2 after a jam is detected in the jam detection process (step S1).

Next, using FIG. 5, we will explain the developer transfer situation by the post-jam process (operation of step S2) in this embodiment.

As a comparative example, we will also explain a case where step S2 (first operation) is not performed and the image forming operation of the image forming device is immediately stopped after a jam occurs, in comparison with the present embodiment.

Figure 5(a) is a schematic diagram showing the transfer of developer in an image forming apparatus according to Example 1 of the present invention. Figure 5(b) is a schematic diagram showing the transfer of developer in a comparative example.

Specifically, Figures 5(a and b) show the state of developer adhering (remaining) on each component at the third station (cyan) and the fourth station (black) of the image forming device 100.

As shown in FIG. 5B, in the comparative example, when a jam occurs (is detected), the drive is immediately stopped and various biases are switched OFF (the image formation operation is stopped), so that the developed (transferred) (jammed) toner H remains on the photosensitive drum.

That is, in the comparative example, if the toner H on the photosensitive drum is not processed (recovered) immediately after a jam, the charge held by the toner H (due to frictional charging) decays. Therefore, during a jam recovery operation, it becomes difficult to transfer (move) the toner H on the photosensitive drum again, and the toner H must be recovered in the recovered toner box 14 of the process cartridge. Therefore, in the comparative example, the jammed toner H on the photosensitive drum cannot be transferred onto the intermediate transfer belt 31 and recovered by the intermediate transfer belt cleaning device (recovered toner box 11B).

In contrast, in this embodiment, as shown in FIG. 5(a), when a jam is detected, the driving of the photosensitive drum is not stopped, and the toner developed (transferred) on the photosensitive drum is completely transferred (transferred) to the intermediate transfer belt 31 before being stopped. Therefore, at the time of the jam recovery operation, the toner H on the photosensitive drum has already been transferred to the intermediate transfer belt, so there is no need to collect a large amount of jammed toner H on the photosensitive drum in the recovered toner box 14 of the process cartridge 7 when a jam occurs.

More specifically, in this embodiment, after detecting the occurrence of a jam, the exposure operation is stopped. Then, the image formation operation (drive) is extended (continued) by (distance d2 from the development unit (development position Y3) to the transfer unit (transfer position Y2)) + (distance d3 from the exposure unit (exposure position Y1) to the development unit (development position Y3)) (note that d1 = d2 + d3).

As a result, in step S2, the developer (jam toner H) (charged on the developing roller) corresponding to the latent image portion that was not developed (transferred) onto the photosensitive drum when the jam occurred can be sufficiently developed (transferred) onto the photosensitive drum 1. Furthermore, the developer can be further transferred (transferred) from the photosensitive drum 1 onto the intermediate transfer belt 31.

This makes it possible to avoid the need to collect the developer (jammed toner H) in the collected toner box 14 of the process cartridge during jam recovery operations. In other words, there is no need to reserve a volume in the process cartridge 7 in advance for collecting jammed toner H, making it possible to handle jams effectively and to improve the minimization of the volume of the collected toner box of the process cartridge 7.

In this embodiment, in step S2, the driving operations (image forming operations) of the process cartridge 7, intermediate transfer belt 31, and secondary transfer roller 33 are continued for the aforementioned "predetermined distance L." As described above, the predetermined distance L corresponds to the distance d1 (= d2 + d3) from the exposure unit (exposure position Y1) to the transfer unit (transfer position Y2). In this embodiment, the operation of the fixing roller 170 is stopped when step S2 is executed.

As a result, even if a fixing roller winding jam as described above occurs, it is possible to effectively prevent the winding from worsening further. This makes it possible to minimize the amount (volume) of toner collected in the recovery toner box 14 of the process cartridge 7, and to prevent the fixing roller winding jam from worsening. In this case, the recording material 35 being transported into the image forming device may bend slightly, but this does not affect the handling of the jam.

Next, immediately after a jam occurs (is detected), the operation of the fixing roller 170 of the image forming apparatus is stopped in step S2, and the upper limit of the predetermined distance L is examined. For example, as an experimental example, if the predetermined distance L is set to exceed the distance d4 (in this embodiment, d4 = 120 mm) from the secondary transfer position Y5 to the fixing position Y4, the following phenomenon may occur. That is, the bending of the recording material 35 increases the possibility that unfixed toner (areas) of images on one sheet (the same) of recording material will "contact" each other, which may result in a jam causing further discomfort to the user.

More specifically, if the image forming operation is continued after a jam is detected in step S2 beyond the distance between the nip of the fixing roller 170 (fixing position Y4) and the nip of the secondary transfer roller 33 (secondary transfer position Y5), the above-mentioned "contact" phenomenon is likely to occur. From this perspective, the upper limit (max) of the "predetermined distance (L)" in step S2 can be set so as not to exceed the distance d4 from the "secondary transfer position Y5" to the "fixing position Y4" (d4≧L).

That is, in this embodiment, the predetermined distance (L) is
It is equal to or longer than the length of the surface 1y of the photosensitive drum 1 in the rotation direction A of the photosensitive drum 1 from an exposure position (Y1) on the surface 1y of the photosensitive drum 1 (image carrier) by the exposure device 30 (exposure member) to a transfer position (Y2) in contact with the intermediate transfer belt 31 (intermediate transfer body),
And it is less than the distance moved by the surface 1y of the photosensitive drum 1 during the period in which the recording medium moves from the secondary transfer position (Y5) on the secondary transfer roller 33 (secondary transfer member) to the fixing position (Y4) on the fixing device 34 (fixing member).

By setting the specified distance within the above range, it is possible to effectively deal with jamming while minimizing the capacity of the recovery developer box provided in the cartridge. In particular, it is possible to effectively reduce the discomfort felt by the user when a jam occurs.

In addition, in the present embodiment shown in FIG. 5(a), when performing the jam recovery operation, the photosensitive drum and intermediate transfer belt 31 are in contact and no transfer bias is applied. Note that a transfer bias may be applied to reduce the amount of toner on the transfer belt that is transferred to the photosensitive drum.

(Modification of the first embodiment)
In this embodiment, an example has been shown in which the system controller 901 (detection member D) stops the laser exposure operation after detecting a jam (step S1) and continues the image forming operation continuously (step S2). However, as a modified example, the image forming operation may be stopped once (step S21) after detecting a jam (step S1), and the control shown in this embodiment (step S2) may be performed immediately thereafter. That is, new steps of "pause (S21)" and "resume (S22)" may be added between steps S1 and S2 shown in FIG. 4.

Even in this case, the image formation operation is stopped again after step S2 (step S3).

That is, when the detection member D of the control unit (901) detects that the transport state of the recording medium is poor, the first operation (S2) and the second operation (S3) are performed in sequence. Here, in the first operation (S2), the rotation operation of the image carrier and the intermediate transfer body is temporarily stopped (step S21), and then the rotation operation of the image carrier and the intermediate transfer body is resumed (step S22).

Then, in the second operation (S3), the rotation of the image carrier and the intermediate transfer body is resumed (S22), and then when the surface of the image carrier has moved a predetermined distance due to the rotation of the image carrier, the rotation of the image carrier is stopped.

As described above, the image forming apparatus of this embodiment can effectively handle jamming while minimizing the capacity of the recovered developer box provided in the cartridge. In other words, it is possible to provide an image forming apparatus in which the amount of toner recovered in the recovered toner box 14 of the process cartridge is minimized even when a jam occurs.

In addition, in this embodiment, the process after jam detection is controlled using the "predetermined distance L," but control may also be performed using a predetermine time t that corresponds to the predetermine distance L depending on, for example, the rotation speed of the image carrier or intermediate transfer body.

In Example 2, another embodiment of the operation (control) when recovering from a jam is described using an image forming device 100 (shown in FIG. 1) similar to that in Example 1 described above.

[Jam recovery operation]
The operation of the present embodiment after recovery from a jammed recording medium will be described with reference to FIGS.

Note that FIG. 6 is a flowchart regarding control during jam (recovery) in an image forming apparatus according to the second embodiment of the present invention.

As shown in FIG. 6, during image formation, the system controller 901 detects the occurrence of a jam (see step S1), performs the initial operation (see steps S2 and S3), and then constantly monitors whether the jam has been cleared (step A1).

In step A1, the system controller 901 detects that the paper has been removed, for example, by the paper detection sensor 161 (detection member D), and determines that the jam has been cleared.

Specifically, in step A1, the operations of steps S2 and S3 described above are performed, and then the "post-jam cleared" state in which the paper has been removed from the jammed area is detected.

After detecting "after jam recovery," the transfer member and the photosensitive drum are changed from a contact state to a separated state (step A2).

Next, the photosensitive drum and the intermediate transfer belt 31 are rotated for a predetermined distance L (or a predetermined time t) to collect the toner on the intermediate transfer belt 31 into the intermediate transfer belt cleaning device 11 (11A, 11B) (Step A3).
Thereafter, the operation of the image forming apparatus is finally stopped (step A4).

Note that in step A2, the transfer and photosensitive drum separation operations are not performed, and the intermediate transfer belt 31 and the photosensitive drum 1 remain in contact when the jam is cleared. The difference between this embodiment (embodiment 2) and embodiment 1 will be explained with reference to FIG. 7.

Figure 7(a) is a schematic diagram showing the transfer of developer in an image forming apparatus according to Example 2 of the present invention. Figure 7(b) is a schematic diagram showing the transfer of developer in Example 1 as a reference example.

As described above, in the first embodiment, the (jammed) toner H transferred from the upstream station (photoconductor drum 1c) onto the intermediate transfer belt remains on the intermediate transfer belt when the jam is cleared. If no processing is performed immediately after the jam, the triboelectric charge held by the toner H on the intermediate transfer belt will decay. Therefore, when the intermediate transfer belt and the photoconductor drum are in contact during the jam clearing operation, the jammed toner H may be re-transferred to the photoconductor drum. Specifically, even if a transfer bias is applied, a small amount of the jammed toner H on the intermediate transfer belt may be re-transferred to the photoconductor drum (1d) at the downstream station (photoconductor drum 1d).

In Example 2, the photosensitive drum and intermediate transfer belt 31 are physically separated when clearing a jam. This eliminates the possibility of the jam occurring in Example 1. As a result, toner transferred (transferred) from the intermediate transfer belt is not collected in the collected toner box 14 (collected developer chamber) of the process cartridge during jam clearance. Therefore, compared to Example 1, Example 2 is more advantageous in minimizing the volume of the collected toner box of the process cartridge.

As with the first embodiment, this embodiment is able to effectively handle jamming while minimizing the capacity of the recovery developer box provided in the cartridge.

In this embodiment, an image forming apparatus 100 (shown in FIG. 1) similar to that of the first embodiment described above is used to explain another embodiment of operational control when a jam occurs.

[Action when a jam occurs]
The operation (control) when a jam of a recording medium occurs in this embodiment will be described with reference to Fig. 8. Fig. 8 is a flow chart relating to the control when a jam (occurrence) occurs in the image forming apparatus according to the third embodiment of the present invention.

In this embodiment, in step B1, the system controller 901 constantly monitors whether a jam has occurred during image formation.

Then, when the system controller 901 (detection member D) detects the occurrence of a jam, it separates the developing roller from the photosensitive drum (step B2).

Next, the system controller 901 rotates the photosensitive drum and intermediate transfer belt by a predetermined distance L (or a predetermined time t) to transfer the toner on the photosensitive drum to the intermediate transfer belt (step B3). In this embodiment, the predetermined distance L corresponds to the distance d2 (d2 = 25 mm) from the development position Y3 to the transfer position Y2.

Then, the operation of the image forming device is stopped (step B4).

Compared to the first embodiment, this embodiment has the effect of further reducing the amount of toner consumed during operation when a jam occurs, which corresponds to the distance from the exposure section (exposure position Y1) to the development position (Y3).

That is, in this embodiment, the predetermined distance (L) is
It is equal to or longer than the length of the surface 1y of the photosensitive drum 1 in the rotation direction A of the photosensitive drum 1 from the development position (Y3) where the photosensitive drum 1 contacts the development roller 17 (developer carrier) to the transfer position (Y2) where the photosensitive drum 1 contacts the intermediate transfer belt 31 (intermediate transfer body),
And it is less than the distance moved by the surface 1y of the photosensitive drum 1 during the period in which the recording medium moves from the secondary transfer position (Y5) on the secondary transfer roller 33 (secondary transfer member) to the fixing position (Y4) on the fixing device 34 (fixing member).

By setting the specified distance (L) within the above range, it is possible to effectively deal with jam processing while minimizing the capacity of the recovery developer box provided in the cartridge. In particular, it is possible to effectively reduce the discomfort felt by the user due to the occurrence of a jam.

[Other embodiments]
The present invention is also applicable to a configuration in which the process cartridge does not include the cleaning member 6 and the collected toner box 14 and the transfer residual toner or fog toner comes into contact with the charging roller 2 during image formation.

In addition, by carrying out the control shown in the first to third embodiments of the present invention, it is also possible to reduce the amount of toner that comes into contact with the charging roller 2 when a jam occurs. This has the effect of suppressing toner contamination of the charging roller 2 and eliminating the need for control to remove toner from the charging roller 2.

The configuration of the present invention can be summarized as follows:

The image forming apparatus 100 of the present invention includes an image carrier (photosensitive drum 1), a developer carrier (developing roller 17), an exposure member (exposure device 30), an intermediate transfer body (intermediate transfer belt 31), and a cleaning member 11A that cleans the surface 31a of the intermediate transfer body. The developer carrier carries a developer that is supplied to the image carrier to develop an electrostatic latent image, and is capable of contacting the image carrier. The exposure device irradiates and exposes the surface of the image carrier.

The image forming apparatus 100 also has a secondary transfer member (secondary transfer roller 33) that performs secondary transfer of the developer image from the intermediate transfer body to a recording medium (recording material 35) for recording the developer image T1. The image forming apparatus 100 also has a fixing member (fixing device 34) that fixes the developer image transferred to the recording medium by the secondary transfer member. The image forming apparatus 100 also has a detection member D that detects the transport state of the recording medium, and a control unit (system controller 901).

The image carrier carries the developer image T1 developed from the electrostatic latent image T0 on its surface 1y and is rotatable. The intermediate transfer body 31 contacts the surface 1y of the image carrier, carries the developer image T1 transferred from the image carrier, and is rotatable.

When the detection member D detects that the transport state of the recording medium is poor, the control unit sequentially performs the first operation (S2) and the second operation (S3), and the developer (jam toner H) remaining on the surface of the image carrier is transferred from the image carrier to the intermediate transfer body. Note that in the first operation (S2), the rotational operation of the image carrier and the intermediate transfer body is continued without stopping. Also, in the second operation (S3), the rotational operation of the image carrier is stopped when the surface of the image carrier moves a predetermined distance (L) due to the rotational operation of the image carrier after the transport state is detected to be poor.

Then, in the first operation, the fixing operation of the fixing member is stopped.

The predetermined distance is equal to or greater than the length of the surface of the image carrier in the rotation direction of the image carrier from the development position (Y3) in contact with the developer carrier to the transfer position (Y2) in contact with the intermediate transfer body,
And, it is equal to or less than the distance that the surface of the image carrier moves during the period in which the recording medium moves from the secondary transfer position (Y5) on the secondary transfer member to the fixing position (Y4) on the fixing member.

This allows the jammed toner remaining on the surface of the image carrier to be efficiently transferred to the intermediate transfer body when a jam occurs, and as a result, the volume of the process cartridge for recovered toner can be reduced. In other words, jam processing can be handled while minimizing the volume of the process cartridge. In particular, it is possible to reduce the wrapping of paper around the fixing member when a jam occurs.

In addition, in the image forming device of the present invention, the specified distance (L) can be set to be equal to or greater than the length of the surface of the image carrier in the rotation direction of the image carrier from the exposure position (Y1) to the transfer position (Y2).

In particular, the specified distance (L) may be the length (d1) of the surface of the image carrier in the rotation direction A of the image carrier from the exposure position Y1 on the surface of the image carrier by the exposure member to the transfer position Y2 where the surface contacts the intermediate transfer body.

By setting the specified distance (L) to length d1 or longer, the toner (jam toner) embedded in the latent image formed by the exposure member until just before the jam occurs can be moved to the intermediate transfer body without leakage.

In addition, in the image forming apparatus of the present invention, the developer carrier (developing roller 17) may be configured to be movable between a first position Z1 where it can come into contact with the image carrier, and a second position Z2 where it can be separated from the image carrier. The control unit can move the developer carrier from the first position to the second position in the first operation (S2).

This reduces the transfer of (jammed) toner from the developer carrier to the image carrier.

When the first operation (S2) is performed with the developer carrier positioned at the second position, the specified distance L can be set as follows:

For example, in the first operation, in the image forming apparatus of the present invention, the specified distance L can be the length (d2) of the surface of the image carrier in the rotation direction A of the image carrier from the development position Y3 to the transfer position Y2.

By setting the specified distance (L) to length d2, jammed toner on the image carrier can be efficiently moved to the intermediate transfer body.

In addition, in the image forming apparatus of the present invention, the intermediate transfer body 31 may be configured to be movable between a third position Z3 where it can come into contact with the image carrier 1, and a fourth position Z4 where it can be separated from the image carrier. After the second operation (S3), the control unit can perform a third operation (A2, A3) in which the intermediate transfer body is positioned at the fourth position and the image carrier and the intermediate transfer body are rotated for a predetermined time t (or a predetermined distance L).

This prevents the toner from being transferred back to the image carrier at the downstream station.

In addition, in the image forming apparatus of the present invention, the intermediate transfer body 31 is configured so that a potential can be applied thereto, and the control unit may perform control in the third operation (A2, A3) so that a potential of the same polarity as that during image formation is applied to the intermediate transfer body.

This can facilitate the transfer of toner from the image carrier to the intermediate transfer body.

The image forming apparatus of the present invention may also have a recovered developer box 11B that contains the developer recovered from the intermediate transfer body 31 by the cleaning member 11A.

The image forming apparatus of the present invention may have a cartridge (process cartridge) 7 that includes an image carrier 1, a second cleaning member (cleaning member) 6 that cleans the surface 1y of the image carrier, and a frame 13A. The cartridge is detachable from the main body 100A of the image forming apparatus. The frame of the cartridge supports the image carrier 1 and the second cleaning member 6, and can be configured to form a recovered developer chamber (recovered toner box) 14 that contains developer recovered from the surface of the image carrier by the second cleaning member.

In the image forming device of the present invention, the cartridge 7 can be provided with a second frame (frame) 4a. The recovered developer chamber (recovered toner box) 14 can be set to have a smaller volume than the developer storage chamber (toner storage chamber) 18b. The second frame 4a of the cartridge can be configured to form a developer storage chamber 18b that stores developer for developing the electrostatic latent image on the image carrier.

The image forming apparatus 100 of the present invention includes an image carrier (photosensitive drum 1), a developer carrier (developing roller 17), an exposure member (exposure device 30), an intermediate transfer body (intermediate transfer belt 31), and a cleaning member 11A that cleans the surface 31a of the intermediate transfer body. The developer carrier carries a developer that is supplied to the image carrier to develop an electrostatic latent image, and is capable of contacting the image carrier. The exposure member irradiates and exposes the surface of the image carrier.

The image forming apparatus also has a secondary transfer member (secondary transfer roller 33) that performs secondary transfer of the developer image from the intermediate transfer body to a recording medium (recording material 35) for recording the developer image T1. The image forming apparatus 100 also has a fixing member (fixing device 34) that fixes the developer image transferred to the recording medium by the secondary transfer member. The image forming apparatus 100 also has a detection member D that detects the transport state of the recording medium, and a control unit (system controller 901).

The image carrier carries the developer image T1 developed from the electrostatic latent image T0 on its surface 1y and is rotatable. The intermediate transfer body 31 contacts the surface 1y of the image carrier, carries the developer image T1 transferred from the image carrier, and is rotatable.

When the detection member D detects that the transport state of the recording medium is poor, the control unit sequentially performs a first operation (S2) and a second operation (S3), and the developer (jam toner H) remaining on the surface of the image carrier is transferred from the image carrier to the intermediate transfer body. In the first operation (S2), the rotational operation of the image carrier and the intermediate transfer body is temporarily stopped, and then the rotational operation of the image carrier and the intermediate transfer body is resumed. In the second operation (S3), the rotational operation of the image carrier and the intermediate transfer body is resumed, and then the rotational operation of the image carrier is stopped when the surface of the image carrier moves a predetermined distance due to the rotational operation of the image carrier.

Then, in the first operation, the fixing operation of the fixing member is stopped.

The predetermined distance is equal to or greater than the length of the surface of the image carrier in the rotation direction of the image carrier from the development position (Y3) in contact with the developer carrier to the transfer position (Y2) in contact with the intermediate transfer body,
And, it is equal to or less than the distance that the surface of the image carrier moves during the period in which the recording medium moves from the secondary transfer position (Y5) on the secondary transfer member to the fixing position (Y4) on the fixing member.

This allows the jammed toner remaining on the surface of the image carrier to be efficiently moved to the intermediate transfer body when a jam occurs, and as a result, the volume of the process cartridge for recovered toner can be reduced. In other words, jam processing can be handled while minimizing the volume of the process cartridge. In particular, it is possible to reduce the wrapping of paper around the fixing member when a jam occurs.

1 (a to d) Photoconductor drum (image carrier)
1y: Surface of photoconductor drum (image carrier) 11A: Cleaning member 17: Developing roller (developer carrier)
30 Exposure device (exposure member)
31 Intermediate transfer belt (intermediate transfer body)
31a: Surface of intermediate transfer belt (intermediate transfer body) 33: Secondary transfer roller (secondary transfer member)
34 Fixing device (fixing member)
35 Recording material (recording medium)
100 Image forming apparatus 901 System controller (control unit)
D Detecting member H (jam) toner (developer)
S2 Step (first operation)
S3 Step (Second Operation)
T0 Electrostatic latent image T1 Developer image Y2 Transfer position Y3 Development position Y4 Fixing position Y5 Secondary transfer position

Claims (11)

a rotatable image carrier that carries on its surface a developer image developed from an electrostatic latent image;
a developer carrier that carries a developer to be supplied to the image carrier in order to develop the electrostatic latent image and is capable of contacting the image carrier;
an exposure member for irradiating and exposing the surface of the image carrier;
an intermediate transfer member that is in contact with a surface of the image carrier and that carries the developer image transferred from the image carrier and is rotatable;
a cleaning member for cleaning the surface of the intermediate transfer body;
a secondary transfer member for secondarily transferring the developer image from the intermediate transfer body to a recording medium on which the developer image is to be recorded;
a fixing member that fixes the developer image transferred onto the recording medium by the secondary transfer member;
A detection member for detecting a conveyance state of the recording medium;
A control unit;
An image forming apparatus comprising:
The control unit is
a first operation of continuing the rotation of the image carrier and the intermediate transfer body without stopping the rotation of the image carrier and the intermediate transfer body when the detection member detects that the conveyance state of the recording medium is defective;
a second operation of stopping the rotation of the image carrier when the surface of the image carrier moves a predetermined distance by the rotation of the image carrier after the defect is detected;
In the first operation,
The fixing operation of the fixing member is stopped,
The predetermined distance is
a length of the surface of the image carrier from a development position in contact with the developer carrier to a transfer position in contact with the intermediate transfer body in a rotation direction of the image carrier, or longer;
and the distance is less than or equal to the distance moved by the surface of the image carrier during the period in which the recording medium moves from the secondary transfer position of the secondary transfer member to the fixing position of the fixing member. The predetermined distance is
2. The image forming apparatus according to claim 1, wherein the length of the surface of the image carrier from an exposure position on the surface of the image carrier by the exposure member to a transfer position in contact with the intermediate transfer body is equal to or greater than the length of the surface of the image carrier in the direction of rotation of the image carrier. The predetermined distance is
3. The image forming apparatus according to claim 2, wherein the distance is a length of the surface of the image carrier from the exposure position to the transfer position in a rotation direction of the image carrier. The developer carrier is
The image bearing member is movable between a first position where the image bearing member can be brought into contact with the image bearing member and a second position where the image bearing member can be separated from the image bearing member.
4. The image forming apparatus according to claim 1, wherein the control section moves the developer carrier from the first position to the second position in the first operation. In the first operation,
5. The image forming apparatus according to claim 4, wherein the predetermined distance is a length of the surface of the image carrier from the development position to the transfer position in a rotation direction of the image carrier. The intermediate transfer member
The image bearing member is movable between a third position where the image bearing member can be brought into contact with the image bearing member and a fourth position where the image bearing member can be separated from the image bearing member.
The image forming apparatus according to any one of claims 1 to 5, characterized in that, after the second operation, the control unit positions the intermediate transfer body at the fourth position and performs a third operation of rotating the image carrier and the intermediate transfer body for a predetermined period of time. The intermediate transfer body is configured so that a potential can be applied thereto,
7. The image forming apparatus according to claim 6, wherein the control section performs control in the third operation so that a potential having the same polarity as that during image formation is applied to the intermediate transfer body. The image forming apparatus according to any one of claims 1 to 7, further comprising a recovered developer box that contains the developer recovered from the intermediate transfer body by the cleaning member. The image carrier;
a second cleaning member for cleaning the surface of the image carrier;
a cartridge including a frame supporting the image carrier and the second cleaning member and defining a recovered developer chamber for accommodating developer recovered from the surface of the image carrier by the second cleaning member,
9. The image forming apparatus according to claim 1, wherein the cartridge is detachable from a main body of the image forming apparatus. the cartridge includes a second frame that defines a developer accommodating chamber that accommodates a developer for developing an electrostatic latent image on the image carrier;
10. The image forming apparatus according to claim 9, wherein the recovered developer chamber has a smaller volume than the developer storage chamber. a rotatable image carrier that carries on its surface a developer image developed from an electrostatic latent image;
a developer carrier that carries a developer to be supplied to the image carrier in order to develop the electrostatic latent image and is capable of contacting the image carrier;
an exposure member for irradiating and exposing the surface of the image carrier;
an intermediate transfer member that is in contact with a surface of the image carrier and that carries the developer image transferred from the image carrier and is rotatable;
a cleaning member for cleaning the surface of the intermediate transfer body;
a secondary transfer member for secondarily transferring the developer image from the intermediate transfer body to a recording medium on which the developer image is to be recorded;
a fixing member that fixes the developer image transferred onto the recording medium by the secondary transfer member;
A detection member for detecting a conveyance state of the recording medium;
A control unit;
An image forming apparatus comprising:
The control unit is
a first operation of temporarily stopping the rotation of the image carrier and the intermediate transfer body when the detection member detects that the conveyance state of the recording medium is poor, and then resuming the rotation of the image carrier and the intermediate transfer body;
a second operation of stopping the rotation of the image carrier when the surface of the image carrier has moved a predetermined distance due to the rotation of the image carrier after the rotation of the image carrier and the intermediate transfer body is resumed;
In the first operation,
The fixing operation of the fixing member is stopped,
The predetermined distance is
a length of the surface of the image carrier from a development position in contact with the developer carrier to a transfer position in contact with the intermediate transfer body in a rotation direction of the image carrier, or longer;
and the distance is less than or equal to the distance moved by the surface of the image carrier during the period in which the recording medium moves from the secondary transfer position of the secondary transfer member to the fixing position of the fixing member.

Images