JP3962730B2 - Image forming apparatus and cartridge - Google Patents

Description

  The present invention relates to an image forming apparatus provided with means for detecting the presence or absence of a detachable cartridge in an image forming apparatus such as a printer, a copier, or a facsimile.

  Conventionally, in an image forming apparatus using an electrophotographic technique, a process cartridge system in which an image carrier and process means acting on the image forming apparatus are integrally formed into a cartridge and the cartridge can be attached to and detached from the main body of the image forming apparatus. Has been. Similarly, a configuration is also known in which a developing cartridge in which a developing device is unitized, a toner cartridge filled with toner, and the like can be attached and detached. Such cartridge systems are widely used in image forming apparatuses because the maintenance of the apparatus can be performed by the user and the convenience of the apparatus is greatly improved.

  When mounting such a cartridge in the image forming apparatus, first, the opening / closing cover of the apparatus main body is opened, the cartridge is mounted in a predetermined place, and then the opening / closing cover is closed. On the other hand, when forming an image, the image forming apparatus needs to confirm that the cartridge is mounted and the open / close cover is closed. For this reason, the image forming apparatus is provided with a detection device such as a switch that interlocks with the opening / closing cover, a micro switch that detects the presence or absence of a cartridge, or a photosensor.

Japanese Unexamined Patent Publication No. 09-106126 (page 8, FIG. 1) Japanese Patent Laid-Open No. 11-050442 (page 9, FIGS. 1, 2, 3, 4)

  However, in the conventional example, in order to detect whether or not the cartridge is mounted on the main body of the image forming apparatus, electronic components such as a micro switch and a photo sensor, and wiring thereof are required.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of detecting the presence or absence of a process cartridge without using a dedicated electronic component.

In order to solve the above-described problems, a typical configuration of an electrophotographic image forming apparatus according to the present invention includes a sensor in the electrophotographic image forming apparatus in which a cartridge is detachable and forms an image on a sheet. A sensor lever that is detected by the position of the sensor lever from the first position to the second position in conjunction with the mounting of the cartridge when the cartridge is mounted on the main body of the electrophotographic image forming apparatus. The sensor lever is moved from the second position to the third position by the contact of the sheet with the first contact portion to be moved and the cartridge mounted on the main body of the electrophotographic image forming apparatus. a second contact portion that moved, the sensor lever having, having a conveying means for conveying the sheet, the first contact portion, the cartridge is When attached to the serial body, characterized in that contact with the abutment rib provided on the cartridge.

  According to the present invention, since a dedicated detection sensor is not used to detect the presence or absence of a cartridge in the image forming apparatus, the production cost can be reduced.

[First embodiment]
A first embodiment of an image forming apparatus according to the present invention will be described. FIG. 1 is a schematic cross-sectional view showing the overall configuration of the image forming apparatus.

  First, the overall configuration of the image forming apparatus will be described. In this embodiment, a laser beam printer P using an electrophotographic system will be described as an example of an image forming apparatus. In this embodiment, as an example of a cartridge that can be attached to and detached from the apparatus main body, a process cartridge 5 having a photosensitive drum 6 as an image carrier will be described.

  In the drawing, the sheets S stacked and stored in the feeding cassette 1 are fed out one by one in the feeding direction as the feeding roller 2 rotates, and are conveyed to the registration roller pair 4 through the intermediate roller pair 3. The The registration roller pair 4 rotates at a predetermined timing and conveys the sheet S between the photosensitive drum 6 and the transfer roller 7 built in the process cartridge 5. A latent image is formed on the photosensitive drum 6 by laser light from the laser scanner unit 8, and the toner image is developed by attaching toner to the latent image. Then, the toner image on the photosensitive drum 6 is transferred to the sheet S by the transfer roller 7. After the transfer of the toner image, the sheet S is sent to the fixing device 9 by the conveying force of the photosensitive drum 6 and the transfer roller 7, where the toner image on the sheet S is fixed. The sheet S that has been fixed is stacked on the stacking tray 12 through the discharge intermediate roller pair 10 and the discharge roller pair 11.

  Next, attachment / detachment of the process cartridge 5 will be described. When the remaining amount of toner in the process cartridge 5 decreases or when a jam occurs in the printer P, the user needs to remove the process cartridge 5 from the printer P. At this time, first, the opening / closing cover 13 which also serves as the apparatus exterior is rotated around the hinge 13a to open the inside of the printer P (direction d1 in the figure), and then the process cartridge 5 is pulled out toward the outside of the apparatus (direction c1 in the figure). ). Then, after replacing with a new process cartridge 5 or removing a jammed sheet remaining in the printer P, the process cartridge is inserted into the inside of the apparatus (direction c2 in the figure), and the opening / closing cover 13 is rotated and closed (d2 in the figure). direction). At this time, the micro switch 14 detects that the opening / closing cover 13 is closed.

  Next, a means for detecting the presence or absence of a sheet loop between transfer and fixing (between the transfer roller 7 and the fixing device 9) will be described. 2 is a diagram for explaining the presence or absence of a sheet or cartridge and the operation of the sensor and lever, FIG. 3 is a diagram for explaining the configuration of the sensor and lever, and FIG. 4 is a diagram for explaining the value and control of the sensor.

  As shown in FIG. 2A, the fixing device 9 includes a pressure roller 9a whose outer peripheral surface is made of rubber and a fixing roller 9b incorporating a halogen heater 9c, and applies heat and pressure to the passing sheet. The toner image is fixed by application. Since the diameter of the pressure roller 9a is changed by the heat applied from the fixing roller 9b, the conveyance speed of the fixing device 9 is increased or decreased accordingly, and the sheet loop amount between transfer and fixing is also changed. Regarding detection of the loop amount of the sheet, as described in JP-A-7-234604, a sensor for detecting the loop amount of the sheet is provided between transfer and fixing, and the conveyance speed of the fixing device or transfer device is determined based on the detection result. The structure which increases / decreases is proposed. The purpose of this is to prevent deterioration of recording quality, such as deterioration of recording accuracy in the transport direction due to the fixing device pulling the sheet too much, and blurring of unfixed images due to shock when the trailing edge of the sheet leaves the transfer device There is.

  As shown in FIG. 2A, in this embodiment, a photo sensor 17 that detects a sheet during transfer and fixing and a sensor lever 16 that turns the photo sensor 17 on and off according to the presence or absence of the sheet are arranged. ing. Here, as shown in FIG. 3, the photosensor 17 includes a light projecting unit 17a and a light receiving unit 17b that receives detection light (not shown) emitted from the light projecting unit 17a, and the slit 17c is obstructed. The detection light is blocked by inserting an object. The sensor lever 16 is biased toward the sheet passing surface by a torsion coil spring 18. Here, the sensor lever 16 is rotatably supported by a support shaft 16d with respect to the image forming apparatus. The support shaft 16d has a flag 16a that is a light shielding portion that can be inserted into the slit 17c of the photosensor 17, a rib 16b that is a first contact portion that contacts the process cartridge 5, and a second contact that contacts the sheet. The rib 16c is a part. The rib 16b is provided at a position outside the conveyance area for conveying the sheet in a direction intersecting with the conveyance direction for conveying the sheet. When the sheet S is conveyed with few loops between transfer and fixing, that is, when the fixing device 9 is pulling the sheet, the flag 16a of the sensor lever 16 shields the photosensor 17 as shown in FIG. Then, the photosensor 17 is turned off (second state). At this time, in order to prevent the fixing device 9 from pulling the sheet S any more, the rotation speed of the driving device (not shown) of the fixing device 9 is reduced by a certain amount to ease the pulling of the sheet S.

  Then, as shown in FIG. 2B, the conveyance speed of the transfer roller 7 becomes faster than the conveyance speed of the fixing device 9, and the sheet S forms a loop and is conveyed along the transfer guide 15. As a result, the sheet is stably conveyed without being pulled by the fixing device 9, and an adverse effect on the recorded image can be prevented. In other words, since the sheet S is not conveyed at a predetermined speed in the transfer portion including the photosensitive drum 6 and the transfer roller 7, it is possible to prevent a problem that the image is disturbed. At this time, the sensor lever 16 is pushed from above by the looped sheet S (third position), rotates against the urging force of the torsion coil spring 18, and does not shield the photosensor 17. ON (first state). Thus, the recording quality is kept good by detecting ON / OFF of the photosensor 17 and controlling the rotational speed of the fixing device 9.

  Next, a mechanism for detecting whether or not the process cartridge 5 is mounted on the printer P using the above-described existing photosensor 17 and sensor lever 16 will be described.

  As shown in FIG. 3, a rib 16 b for rotating the sensor lever 16 is provided outside the paper passing area at the end of the sensor lever 16. On the other hand, as shown in FIG. 2A, abutting ribs 5a are provided at positions corresponding to the ribs 16b of the process cartridge 5. The abutting rib 5a contacts the rib 16b of the sensor lever 16 when the process cartridge 5 is correctly mounted on the printer P, and moves to a position where the photosensor 17 is shielded (second position). The flag 16a is formed in a size (positional relationship) that turns the photosensor 17 OFF (second state).

  As shown in FIG. 2C, when the user removes the process cartridge 5, the abutting rib 5a does not come into contact with the rib 16b by pulling out the process cartridge 5 (direction p in the drawing). The sensor lever 16 is urged toward the sheet passing surface by the torsion coil spring 18, but when it is not regulated by the abutment rib 5a, the sensor lever 16 is further activated toward the sheet passing surface and is regulated by the stopper 15a of the transfer guide 15. Thus, the rotation is stopped (first position). At this time, since the flag 16a does not shield the photosensor 17, the photosensor 17 is turned on (first state).

  Here, as shown in FIG. 1, a jam detection sensor for detecting a jam of a sheet is provided at several places on the sheet conveyance path of the printer P. Further, a jam detection sensor 30 is provided as a second sensor capable of detecting the presence or absence of a sheet on the downstream side of the registration roller pair 4 and on the downstream side of the pressure roller 9a and the fixing roller 9b of the fixing device 9. The jam detection sensor 30 is originally provided for the purpose of detecting a jam in the conveyance path, and is not newly provided for detecting the presence or absence of a sheet at the position of the photosensor 17. The specific device for the jam detection sensor 30 may be any known device, and may be a combination of a photo interrupter and a lever, or a reflective sensor having a light emitting portion and a light receiving portion. Good.

  FIG. 4A is a diagram for explaining the correspondence between the values of the photo sensor 17 and the jam detection sensor 30 and the situation. The photosensor 17 generates four phenomena depending on the presence or absence of a cartridge and the presence or absence of a sheet as described above, but is turned off only when there is a cartridge and no sheet is detected (see FIG. 2A). The jam detection sensor 30 is turned ON / OFF depending on the presence / absence of a sheet. There are three phenomena when the photosensor 17 is ON. Therefore, since the presence or absence of the sheet can be detected by the jam detection sensor 30, when the detection results of the photo sensor 17 and the jam detection sensor 30 are combined, the photo sensor 17 is ON and the jam detection sensor 30 is OFF. In this case, it can be determined that there is no cartridge.

  FIG. 4B is a flowchart for explaining a part of the initialization operation performed at a predetermined timing. The predetermined timing is when the power is turned on, when returning from standby, or when the detection state of the sensor changes during standby. As shown in the figure, the output of the jam detection sensor 30 is first referred to (S1), and if it is ON, it is determined that a jam sheet exists, and this is notified by a display unit or the like (S2). If it is OFF, the output of the photo sensor 17 is referred to (S3), and if it is ON, it is informed that there is no cartridge and the process ends (S4). If it is OFF, the output of the micro switch 14 is referred to. If it is OFF, it is informed that the opening / closing cover 13 has been released, and the process ends (S6). If it is ON, the print standby permission state is set and the process ends (S7).

  That is, when the jam detection sensor 30 is OFF and the photosensor 17 is OFF, it means that the abutting rib 5a of the process cartridge 5 is in contact with the rib 16b of the sensor lever 16, and the process It can be determined that the cartridge 5 is attached to the printer P.

  With the configuration as described above, the presence / absence of a cartridge can be reliably and inexpensively detected using an existing sensor provided for detecting a sheet. Accordingly, the production cost of the apparatus can be reduced.

  In this embodiment, the process cartridge 5 is provided with the abutting rib 5a. However, the rib 16b may be extended in the attaching / detaching direction of the process cartridge 5. Thereby, the freedom degree of the shape of the process cartridge 5 can be increased.

[Second Example]
A second embodiment of the image forming apparatus according to the present invention will be described. FIG. 5 is a diagram for explaining the presence or absence of a sheet or cartridge and the operation of the sensor and lever. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In the first embodiment, the sensor lever 16 and the abutment rib 5a which is a part of the process cartridge 5 are in direct contact with each other. In contrast, the present embodiment is configured to include a pressing member that operates the lever, and the lever is operated when the pressing member comes into contact with the cartridge.

  As shown in FIG. 5A, a pressing member 20 is rotatably provided at an intermediate position between the sensor lever 16 and the process cartridge 5. The pushing member 20 is biased toward the process cartridge 5 by a torsion coil spring 19. In the state where the process cartridge 5 is mounted, the process cartridge 5 abuts against the tip 20a of the push member 20, and the push member 20 is rotated against the urging force of the torsion coil spring 19, so that the other end 20b of the push member 20 is rotated. Opens away from the rib 16b. As a result, the sensor lever 16 is rotated by the urging force of the torsion coil spring 18 and stops in a state where it protrudes into the sheet conveyance path (second position). At this time, the flag 16a of the sensor lever 16 shields the photosensor 17, and the output of the sensor is turned off.

  As shown in FIG. 5B, when pressed from above by the loop formed on the sheet S, the sensor lever 16 rotates against the urging force of the torsion coil spring 18 (third position). At this time, since the flag 16a does not shield the photosensor 17, the photosensor 17 is turned on.

  As shown in FIG. 5C, in the state where the process cartridge 5 is removed, the front end 20a is opened, so that the pushing member 20 is rotated by the urging force of the torsion coil spring 19 (first position). . Then, the other end 20b of the pressing member 20 abuts against the rib 16b of the sensor lever 16 and urges it, so that the sensor lever 16 rotates against the urging force of the torsion coil spring 18, and the flag 16a causes the photosensor 17 to move. Since the light is not shielded, the photosensor 17 is turned on.

  Even in the above-described configuration, the correspondence between the values of the photosensor 17 and the jam detection sensor 30 and the situation and the control for this are the same as those shown in the first embodiment (see FIG. 4).

  By configuring as in the present embodiment, it is not necessary to provide a contact portion such as the abutment rib 5a on the process cartridge 5. Therefore, the degree of freedom of the shape of the process cartridge 5 can be increased.

  In the present embodiment, there are two positional relationships of the ribs 16b with respect to the photosensor 17, so that a configuration in which ON (first state) and OFF (second state) are switched may be employed.

[Third embodiment]
A third embodiment of the image forming apparatus according to the present invention will be described. FIG. 6 is a diagram illustrating a conventional configuration of the fixing device 9, and FIG. 7 is a diagram illustrating the presence or absence of a sheet or a cartridge and the operation of a sensor and a lever. The same reference numerals are given and description thereof is omitted.

  In the second embodiment, the push member 20 that contacts the cartridge and operates the lever is provided at the intermediate position between the sensor lever 16 and the process cartridge 5. In this embodiment, an example is shown in which this pressing member is also used as a protective member for preventing the user's finger f from entering the fixing device 9.

  As shown in FIG. 6, conventionally, a fixing inlet guide 21 has been provided on the upstream side and the upper side in the conveying direction of the fixing device 9. This is to prevent the user from quitting and inserting the finger f into the fixing device 9 during the jam processing and touching the fixing roller 9b and the pressure roller 9a that are heated by the halogen heater 9c. It is. Accordingly, it is preferable that the fixing inlet guide 21 closes the inlet of the fixing device 9 as much as possible during the jam processing. However, the sheet being conveyed is rubbed during image formation to disturb the toner image before fixing, or a curled sheet. May cause jamming. For this reason, it is preferable that the fixing inlet guide 21 is retracted from the inlet of the fixing device 9 during image formation, and closes the inlet of the fixing device 9 during jam processing.

  Therefore, as shown in FIG. 7A, the guide member 22 as a pressing member according to the present embodiment is disposed on the upstream side of the fixing unit so as to be rotatable about a shaft 22a. In a state where the process cartridge 5 is mounted, the process cartridge 5 comes into contact with the tip 22b of the guide member 22 and rotates the guide member 22 against its own weight. Then, the other end 22c of the guide member 22 is also rotated and pushed up, and the entrance of the fixing device 9 is opened. At this time, since the other end 22c is also separated from the sensor lever 16, the sensor lever 16 is rotated by the urging force of the torsion coil spring 18 and stops in a state of protruding into the sheet conveying path. At this time, the flag 16a of the sensor lever 16 shields the photosensor 17, and the output of the sensor is turned off.

  As shown in FIG. 7B, in the state where the process cartridge 5 is removed, the tip 22b is opened, so that the guide member 22 rotates so that the other end 22c is lowered by its own weight. Then, since the guide member 22 closes the entrance of the fixing device 9, the insertion of the user's finger f is prevented. At the same time, the other end 22c of the guide member 22 descends and presses the sensor lever 16 from above, so that the sensor lever 16 rotates against the biasing force of the torsion coil spring 18. At this time, since the flag 16a does not shield the photosensor 17, the photosensor 17 is turned on.

  Even in the above-described configuration, the correspondence between the values of the photosensor 17 and the jam detection sensor 30 and the situation and the control for this are the same as those shown in the first embodiment (see FIG. 4).

  As described above, the pressing member that operates the lever by being in contact with the cartridge also serves as the fixing inlet guide on the upstream side of the fixing device, so that it is not necessary to provide a new pressing member, which increases the production cost. Can be prevented. Further, since it is not necessary to provide a contact portion (rib or the like) for rotating the lever on the cartridge, it is possible to increase the degree of freedom of the shape of the cartridge.

  In each of the above-described embodiments, as the sensor for detecting the presence or absence of the process cartridge 5, an example is shown in which the sensor for detecting the loop amount of the sheet is also used. However, the present invention is not limited to this, and may be, for example, a width sensor for separating the width of the sheet. In other words, any sensor that is not used for the purpose of detecting a jam can also be used as a sensor for detecting a cartridge. Further, even a jam detection sensor can be used as a sensor for detecting a cartridge as long as it includes another sensor that detects the presence or absence of a sheet at the position of the sensor.

  The sensor may be disposed at any position that can be related not only to the transfer and fixing (between the transfer roller 7 and the fixing device 9) but also to the cartridge attaching / detaching operation. Therefore, for example, the same effect can be obtained even in other places such as between the registration roller pair 4 and the transfer roller 7. Furthermore, the present invention can be similarly applied not only to a process cartridge but also to a developing cartridge and a toner cartridge as a cartridge.

  In each of the above embodiments, the combination of the photo sensor 17 and the sensor lever 16 is only ON / OFF, and even if the photo sensor 17 is ON, it cannot be determined whether there is a sheet or no cartridge. Judgment is made by using a sensor (jam detection sensor) together. However, in FIG. 2C, for example, the position of the flag 16a with respect to the photosensor 17 is on the opposite side of the photosensor 17 between when the sheet is detected and when there is no cartridge. Therefore, if a two-stage switch such as two photosensors is used, the presence or absence of a cartridge can be detected without using another sensor.

  The present invention can be used in an image forming apparatus including a detachable cartridge.

1 is a schematic cross-sectional view illustrating an overall configuration of an image forming apparatus. It is a figure explaining the presence or absence of a sheet | seat or a cartridge, and operation | movement of a sensor and a lever. It is a figure explaining the composition of a sensor and a lever. It is a figure explaining the value and control of a sensor. It is a figure explaining the presence or absence of a sheet | seat or a cartridge, and operation | movement of a sensor and a lever. 2 is a diagram illustrating a conventional configuration of a fixing device 9. FIG. It is a figure explaining the presence or absence of a sheet | seat or a cartridge, and operation | movement of a sensor and a lever.

Explanation of symbols

P ... Laser beam printer S ... Sheet f ... Finger 1 ... Feed cassette 2 ... Feed roller 3 ... Intermediate roller pair 4 ... Registration roller pair 5 ... Process cartridge 5a ... Abutting rib 6 ... Photoconductor drum 7 ... Transfer roller 8 ... Laser scanner unit 9 ... Fixing device 9a ... Pressure roller 9b ... Fixing roller 9c ... Halogen heater
10… discharge intermediate roller pair
11… discharge roller pair
12… Loading tray
13… Open / close cover
13a… Hinge
14… Micro switch
15… Transfer Guide
15a ... stopper
16 Sensor lever
16a: Flag part
16b ... rib
17… Photo sensor
18, 19 ... Torsion coil spring
20… Pushing member
20a ... tip
20b ... the other end
21… Fixing entrance guide
22… Guide material
22a ... axis
22b ... tip
22c… the other end
30… Jam detection sensor

Claims (9)

In an electrophotographic image forming apparatus in which a cartridge is detachable and forms an image on a sheet,
A sensor,
A sensor lever detected by the sensor, wherein when the cartridge is attached to the main body of the electrophotographic image forming apparatus, the sensor lever is moved from a first position to a second position in conjunction with the attachment of the cartridge; A first abutting portion to be moved to a position, and the sheet abutting in a state where the cartridge is mounted on the main body of the electrophotographic image forming apparatus, whereby the sensor lever is moved from the second position to the third position. A sensor lever having a second abutting portion to be moved to a position;
Conveying means for conveying the sheet,
The electrophotographic image forming apparatus, wherein the first abutting portion abuts against a butting rib provided on the cartridge when the cartridge is mounted on the main body . The electrophotographic image forming apparatus includes a transfer unit for transferring the developed image formed on the electrophotographic photosensitive member of the cartridge to the sheet, and a fixing unit for fixing the developed image transferred to the sheet to the sheet. Fixing means,
The sensor lever is provided between the transfer unit and the fixing unit, and when the sheet loops a predetermined amount between the transfer unit and the fixing unit, the sheet contacts the second contact portion. The electrophotographic image forming apparatus according to claim 1, wherein the image forming apparatus is in contact with the electrophotographic image forming apparatus. The electrophotographic image forming apparatus is a pressing member movably provided on the main body, and has a pressing member that contacts the first contact portion and holds the sensor lever in a first position,
When the cartridge is mounted on the main body of the electrophotographic image forming apparatus, the pressing member moves in contact with the cartridge so that the pressing member and the first contact portion are separated from each other. The electrophotographic image forming apparatus according to claim 1, wherein the sensor lever moves from the first position to a second position. The electrophotographic image forming apparatus according to claim 3 , wherein the first position and the third position are the same position. The pressing member is provided at a position that prevents an operator from contacting the fixing unit when the cartridge is not attached to the main body of the electrophotographic image forming apparatus. The electrophotographic image forming apparatus according to claim 3 or 4 . The sensor includes a light projecting unit and a light receiving unit that receives detection light emitted from the light projecting unit,
The sensor lever, the electrophotographic image forming apparatus according to any one of claims 1 to 5, characterized in that it has a light blocking part for blocking the detection light in the second position. Further, the electrophotographic image forming apparatus has a second sensor for detecting the presence or absence of the sheet provided on the upstream side or the downstream side of the sensor lever,
When the second sensor detects that the sheet is not present, and the sensor detects that the sensor lever is positioned at the second position, the cartridge is disposed on the electrophotographic image forming apparatus. an apparatus according to any one of claims 1 to 6, characterized in that judged to be attached to the main body. Wherein the sensor lever is the first position, or, when it is detected by the sensor to be located in the third position, any one of claims 1 to 7, characterized in that the image forming operation is not performed The electrophotographic image forming apparatus described in 1. Wherein the first contact portion in a direction intersecting the transport direction for transporting the sheet, one of the claims 1 to 8, characterized in that provided at a position outside the conveying area for conveying the sheet An electrophotographic image forming apparatus according to claim 1.

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