JP2020071294A - Image forming apparatus - Google Patents

Abstract

To provide means that makes it possible to detect a medium remaining between a first conveying section and a second conveying section during insertion/withdrawal of an insertion/withdrawal unit.SOLUTION: An image forming apparatus comprises: a first conveying section that conveys a medium; a second conveying section that is arranged on the downstream side of the first conveying section in a medium conveyance direction and conveys the medium delivered from the first conveying section; a medium detection section that is arranged between the first conveying section and the second conveying section and detects the state of the medium between the first and second conveying sections; and an insertion/withdrawal unit that is provided insertable/withdrawable into/from an apparatus body and has the second conveying section. The medium detection unit has a first lever that detects the state of conveyance of the medium, a second lever that detects the presence or absence of a remaining medium, and a lever rotation detection sensor that detects the rotation of the first and second levers.SELECTED DRAWING: Figure 19

Description

  The present invention relates to an image forming apparatus provided with an insertion / removal unit such as a fixing unit that can be inserted / removed, and more particularly to detection of a residual sheet when a jam occurs.

  In a conventional image forming apparatus that prints on continuous paper, the state of the continuous paper at the time of occurrence of a jam is detected by the output from a slack sensor provided between a transfer unit and a fixing unit (for example, Patent Document 1). reference.).

JP, 2011-164396, A (paragraph 0054-0061, Drawing 5).

Generally, the fixing unit is provided so that it can be inserted into and removed from the apparatus main body for maintenance and unit replacement.
In the case of Patent Document 1, since the image forming apparatus prints on continuous paper, no problem occurs when the fixing unit is inserted or removed. However, in the case of an image forming apparatus that prints on sheet-shaped paper, a jam occurs. The jammed paper may remain between the transfer unit and the fixing unit when the fixing unit is inserted or removed, and there is a problem that it is difficult to detect the paper state in this case.
The present invention has been made to solve the above problems, and an object of the present invention is to provide means for enabling detection of a sheet remaining between a transfer unit and a fixing unit when the fixing unit is inserted and removed. To do.

  According to the present invention, in order to solve the above-mentioned problems, an image forming apparatus is disposed on a first transporting unit that transports a medium, and on the downstream side of the first transporting unit in the medium transporting direction. A second transport unit for transporting the medium delivered from the unit, and a state of the medium between the first and second transport units, the medium being disposed between the first transport unit and the second transport unit. A medium detection unit for detecting the state of the medium, and an insertion / removal unit that is provided so that it can be inserted into and removed from the apparatus main body and has the second conveyance unit, and the medium detection unit includes a first lever that detects a medium conveyance state. A second lever for detecting the presence or absence of the residual medium, and a lever rotation detection sensor for detecting the rotation of the first and second levers.

  As a result, the present invention has an effect that it is possible to easily detect the medium remaining between the first transport section and the second transport section when the insertion / removal unit is inserted / removed in the jammed paper removing operation. ..

Explanatory diagram showing a schematic configuration of the printer of the embodiment Explanatory drawing showing the external appearance of the printer of the embodiment Explanatory drawing showing the front cover open state of the printer of the embodiment Explanatory drawing showing the opened state of the front cover and the top cover of the printer of the embodiment Explanatory drawing showing the fixing unit pulled out state of the printer of the embodiment Explanatory diagram showing the external appearance of the fixing unit of the embodiment Part A enlarged view of FIG. Block diagram showing the control system of the printer of the embodiment Explanatory diagram showing the external appearance of the paper detection unit of the embodiment Explanatory drawing showing the paper detection lever of the embodiment Explanatory diagram showing the operation of the paper detection unit of the embodiment Explanatory diagram showing the operation of the paper detection unit of the embodiment Explanatory drawing showing the operation when the amount of invasion of the leading edge of the sheet of the embodiment into the fixing unit is large. Explanatory drawing showing the operation when the amount of invasion of the leading edge of the sheet of the embodiment into the fixing unit is large. Explanatory drawing showing an operation when the amount of invasion of the leading edge of the sheet of the embodiment into the fixing unit is small Explanatory drawing showing an operation when the amount of invasion of the leading edge of the sheet of the embodiment into the fixing unit is small Explanatory drawing showing an operation when the amount of invasion of the leading edge of the sheet of the embodiment into the fixing unit is small Explanatory drawing showing an operation when the amount of invasion of the leading edge of the sheet of the embodiment into the fixing unit is small Flowchart showing the printing process of the embodiment

  Embodiments of an image forming apparatus according to the present invention will be described below with reference to the drawings.

The printer of this embodiment will be described below with reference to FIGS. 1 to 19.
The printer 1 as the image forming apparatus of the present embodiment is an electrophotographic printer that prints an image based on print data on a sheet of paper P as a printing medium, and has the configuration shown in FIGS. 1 and 2. Equipped with.

  In the main body 1a of the printer 1, a paper transport path 2 (see the one-dot chain line shown in FIG. 1) serving as a media transport path is arranged in a substantially S shape at the center thereof, and a paper P is accommodated in the lower portion. The sheet cassette 3 for storing the sheets is arranged, the discharge tray 4 for collecting the printed sheets P is provided in the upper part, and the operation display unit 5 is provided on the front side of the discharge tray 4.

  The paper feed path 2, the paper feed section 6, the registration roller pair 7, the passage detection sensor 8a, and the feed roller are provided along the paper feed direction (see the arrow indicated by the one-dot chain line in FIG. 1) as the medium feed direction. Pair 9a, passage detection sensor 8b, conveyance belt 11, sheet detection unit 40 (details will be described later), fixing unit 12, passage detection sensor 8c, conveyance roller pair 9b, switching blade 13, ejection sensor 14, ejection roller pair 15 Are arranged in order.

  Further, the apparatus body 1a is provided with a conveyance guide 16a between the paper feed section 6 and the registration roller pair 7, and an insertion / extraction guide 17 is provided above the fixing unit 12 and the conveyance belt 11 to convey the paper. Below the path 2, a front / back reversing conveyance path 19 (see a chain double-dashed line shown in FIG. 1) including a plurality of conveyance roller pairs 18 and a conveyance guide 16b is arranged.

  As shown in FIG. 2, the operation display unit 5 is provided with a display screen 5a such as an LCD having a touch panel on its surface, and a plurality of operation keys 5b such as a numeric keypad for receiving key operations by the user. The display screen 5a displays the status of the printer 1, predetermined information for the user, various screens such as an input screen, and an input means including a touch panel and operation keys 5b allows the user to input an instruction or the like. Accept.

The paper feed unit 6 is arranged at a connection portion between the paper transport path 2 and the paper cassette 3, and is provided with a pickup roller 6a, a paper feed roller 6b, and a separation roller 6c arranged opposite to the pickup roller 6a. The paper P is delivered to the paper transport path 2 one by one.
The registration roller pair 7 is arranged between the paper feed unit 6 and the conveyance roller pair 9a, corrects skew of the paper P fed from the paper feed unit 6, and conveys it to the downstream side.

The passage detection sensors 8a, 8b, 8c are mechanical or optical sensors, respectively, and detect the presence or absence of the paper P conveyed on the paper conveyance path 2.
The conveying roller pairs 9a and 9b sandwich and convey the sheet between the pair of rollers arranged to face each other.
The conveyor belt 11 as the first conveyor unit is an endless belt made of a plastic film, is rotationally driven (counterclockwise in FIG. 1) by the drive roller 11a, and is tensioned in the lower right direction in FIG. 1 by the tension roller 11b. Is provided, and the sheet P adsorbed by the electrostatic effect is conveyed toward the fixing unit 12.

  The fixing unit 12 includes a heat belt 21 heated by a fixing heater 21a, a pressure roller 22 (see FIG. 11) that is arranged to face the heat belt 21, and is rotationally driven by a fixing motor 12a (see FIG. 8), and a heat belt. A fixing temperature sensor 23 such as a thermistor for detecting the surface temperature of 21 is provided.

The switching blade 13 is arranged between the conveyance roller pair 9a and the discharge sensor 14 at a branch portion between the paper conveyance path 2 and the front / back reversal conveyance path 19, and guides the paper P to the ejection roller 15 and the front / back reversal conveyance. It has a function of switching to the direction of leading to the path 19, and is normally positioned at a position of guiding the paper P transported on the paper transport path 2 to the discharge roller 15.
The discharge sensor 14 is a mechanical or optical sensor arranged immediately upstream of the discharge roller pair 15 and detects the trailing edge of the paper P conveyed by the discharge roller pair 15.

The discharge roller pair 15 is arranged on the most downstream side of the paper conveyance path 2 and holds the paper P between the pair of rollers arranged to face each other, so that the printed paper P is placed on the discharge tray 4 outside the apparatus main body 1a. To discharge.
The front-back reversing conveyance path 19 conveys the switching blade 13 when the ejection sensor 14 detects the trailing edge of the paper P which has been printed on the front surface and has been ejected onto the ejection tray 4 by the ejection roller pair 15. The direction is switched to the reverse conveyance direction (see the arrow attached to the two-dot chain line in FIG. 1), the discharge roller pair 15 is rotated in the reverse direction, and the conveyance roller pair 18 is rotated in the reverse conveyance direction to convey to the registration roller pair 7. ..

  Four independent image forming units 24y, 24m, 24c, and 24k are arranged in the order of developing the toner image along the sheet conveying direction on the upper portion of the conveying belt 11 in the apparatus main body 1a of the present embodiment. The image forming unit 24 has a toner cartridge 25 containing toner as a developer of each color set, that is, Y color (yellow), M color (magenta), C color (cyan), and K color (black). Are detachably provided, and these four image forming units 24 have the same structure except for the toner color, and therefore one image forming unit 24y will be described below.

The image forming unit 24y is integrally configured of the photosensitive drum 26 and a charging roller, a developing roller, a developing blade, a supply roller, etc., which are arranged around the photosensitive drum 26, and is detachably attached to the printer 1.
An exposure head 27 is disposed above the photoconductor drum 26 of each image forming unit 24 so as to face it.

The exposure head 27 has a light emitter such as an LED light or a laser light, and irradiates the surface of the photoconductor drum 26 with light corresponding to an image signal to form an electrostatic latent image.
A toner image as a developer image formed by each image forming unit 24 is transferred onto a sheet conveyed by the conveyor belt 11 in the conveyor belt 11 on the opposite side of the photoreceptor drum 26 with the conveyor belt 11 interposed therebetween. A transfer roller 28 for doing so is arranged oppositely.

The paper P on which the toner image is transferred is conveyed to the fixing unit 12 by the conveyor belt 11, and in the fixing unit 12, the paper P delivered from the conveyor belt 11 is a nip portion between the heat belt 21 and the pressure roller 22. While being conveyed by, the toner image on the paper is fixed by pressure and heat.
The second transport unit of this embodiment is composed of a heat belt 21 and a pressure roller 22. Further, the transfer unit 29 is configured by the conveyor belt 11 that is stretched between the driving roller 11 a and the tension roller 11 b, a plurality of transfer rollers 28 that are arranged in the conveyor belt 11, and the like.

As shown in FIG. 3, on the front side of the apparatus main body 1a of the printer 1 of the present embodiment, a front cover 31 that pivots around a hinge provided in the lower portion is provided so as to be openable and closable, and the opening / closing detection is made. It is detected by the opening / closing detection sensor 32 as a unit.
In addition, as shown in FIG. 4, an upper surface cover 33 that pivots around a hinge provided on the back side is openably and closably provided on the upper portion of the apparatus main body 1a, and is used for replacing the image forming unit 24 or the like. To open the top cover 33, lift the front side after opening the front cover 31.

The paper cassette 3 can be pulled out to the front side of the apparatus body 1a.
As shown in FIG. 5, in the fixing unit 12 of the present embodiment, when the hook 34 of the lock mechanism is removed with the front cover 31 and the upper cover 33 closed, the fixing unit 12 is directly pulled out from the upper surface side of the apparatus main body 1a to the outside. 6 and 7, the sheet detection lever 41 and the residual detection lever 42 of the sheet detection unit 40, which will be described later, are provided on the upper and front frames 12b of the fixing unit 12 so as to be directly inserted from the outside. Is provided with a notch through which

The insertion / removal of the fixing unit 12 is detected by an insertion / removal detection sensor 35 as an insertion / removal detection unit provided in the apparatus body 1a (see FIG. 6).
The insertion / removal detection sensor 35 is an optical sensor in which a light emitting portion and a light receiving portion are arranged opposite to each other with the tip of the hook 34 of the lock mechanism interposed therebetween, and the light from the light emitting portion is blocked by the tip of the hook 34. Is detected by the light receiving section to detect that the fixing unit 12 is mounted, and when the light receiving section receives light from the light emitting section, pulling out of the fixing unit 12 is detected.

The control unit 36 of the printer 1 shown in FIG. 8 has a function of controlling each unit in the printer 1 to execute print processing and the like based on the received print data.
The storage unit 37 stores programs executed by the control unit 36, various data used for the programs, processing results by the control unit 36, and the like.

Based on a command from the control unit 36, the transport driving unit 38 controls the pickup roller 6a and the paper feeding roller 6b of the paper feeding unit 6, the registration roller pair 7, each transport roller pair 9, the pressure roller 22, and the transport belt 11. The drive roller 11a, the photosensitive drum 26 of each image forming unit, the switching blade 13, the discharge roller 15 and the like are driven to convey the paper P.
The power supply unit 39 generates a high voltage such as a developing voltage applied to the developing roller of each image forming unit 24 or a transfer voltage applied to the transfer roller 28 based on a command from the control unit 36, and also the passage detection sensor 8 A low voltage supplied to the lever rotation detection sensor 44 (described later) of the paper detection unit 40, the ejection sensor 14, and the like is generated.

As shown in FIG. 1, the paper detection unit 40 as the medium detection unit of the present embodiment is provided between the transport belt 11 of the transfer unit 29 and the nip portion between the heat belt 21 and the pressure roller 22 of the fixing unit 12. Is located in.
As shown in FIGS. 9 and 10, the paper detection unit 40 is provided inside the frame 12b (see FIG. 11) of the fixing unit 12 and serves as a paper detection lever 41 as a first lever and a second lever as a second lever. The residual detection lever 42, a shielding portion 43 as a shielding member, a lever rotation detection sensor 44, an urging spring 45, a locking portion 46, a holding portion 47 provided in the apparatus main body 1a, and the like.

Further, the residual detection lever 42 and the shielding portion 43 are formed integrally with the paper detection lever 41.
The sheet detection lever 41 is a plate-shaped member that rotates about a rotation shaft 41a, and is biased by a biasing spring 45 such as a torsion spring in a direction toward the upstream side in the sheet transport direction (counterclockwise in FIG. 10). When the shielding portion 43 abuts on the locking portion 46 provided on the frame 12b of the fixing unit 12, the rectangular paper abutting portion 41b provided on the leading end portion of the paper feeding path 2 is provided. Stop at a position that projects inward (called the home position).

The residual detection lever 42 is a plate-like member that extends below the paper conveyance path 2 from the paper detection lever 41 toward the upstream side in the paper conveyance direction. The residual detection lever 42 rotates together with the paper detection lever 41 to rotate the paper detection lever 41. When the sheet stops at the original position, the sheet stops at the position where the upper surface is parallel to the sheet conveying path 2 (see FIG. 11).
The lever rotation detection sensor 44 is an optical sensor in which a light emitting unit and a light receiving unit are arranged to face each other with the shielding unit 43 interposed therebetween. The lever rotation detection sensor 44 mainly receives light when the shielding unit 43 blocks light from the light emitting unit. When the sheet detecting lever 41 is stopped at the original position by detecting the sheet, the sheet P is detected when the light from the light emitting section is received by the light receiving section.

The holding unit 47 is a plate-like member provided below the paper transport path 2 in a direction orthogonal to the paper transport direction, and is disposed between the fixing unit 12 and the transfer unit 29.
Further, a cutout portion 47a through which the tip of the residual detection lever 42 passes with the rotation of the paper detection lever 41 is provided in the upper portion of the holding portion 47, and when the paper detection lever 41 stops at the original position. , The tip of the residual detection lever 42 stops in the notch 47a.
The operation of the sheet detecting unit 40 of this embodiment will be described below with reference to FIGS. 11 to 18.

In the normal printing process, until the paper P is conveyed by the conveyor belt 11 of the transfer unit 29, as shown in FIG. 11, in the paper detection lever 41 of the paper detection unit 40, the shielding unit 43 is the locking unit. In the state of being in contact with the paper 46, the paper contact portion 41b is stopped at the original position where it projects into the paper transport path 2.
When the sheet P is conveyed into the fixing unit 12 and the leading edge of the sheet P pushes the sheet contact portion 41b of the sheet detection lever 41, the sheet detection lever 41 causes the urging force of the urging spring 45 as shown in FIG. Against this, it rotates toward the downstream side in the paper transport direction.

At this time, the shielding portion 43 deviates from the optical axis of the lever rotation detection sensor 44, and the arrival of the leading edge of the paper P to the fixing unit 12 is detected.
When a jam occurs during the printing process, the printer 1 releases the pressing of the heat belt 21 and the heating roller 22 of the fixing unit 12 and stops the conveyance of the paper P.

When the user of the printer 1 normally removes the jammed paper P (referred to as jammed paper), the front cover 31 is usually opened, and the stopped paper P is pulled out from the front side to remove jammed paper. It is taken out of the main body 1a and the front cover 31 is closed.
At this time, in the present embodiment, since the pressing of the heat belt 21 and the heating roller 22 of the fixing unit 12 is released, the jammed paper is stopped regardless of where the jammed paper is stopped on the paper conveyance path 2. Can be easily taken out of the apparatus main body 1a.

  During the operation of removing the jammed paper, the fixing unit 12 of this embodiment can be directly pulled out from the apparatus main body 1a to the outside with the front cover 31 and the upper cover 33 closed. There is a case where a person releases the fixing unit 12 by releasing the lock mechanism while leaving the jammed paper in the paper conveyance path 2.

  After the fixing unit 12 is pulled out, when the user inserts the fixing unit 12 into the original position, as shown in FIG. 13, when the amount of the leading edge of the jammed paper entering the fixing unit 12 is large, it is inserted. The lower part of the fixing unit 12 pushes the front end of the paper P and bends it toward the holding portion 47. After the fixing unit 12 is mounted, the front end of the paper P is the frame of the fixing unit 12 as shown in FIG. It enters between 12b and the holding part 47.

  At this time, the tip of the residual detection lever 42 comes into contact with the upper surface of the paper P during insertion of the fixing unit 12, and the upstream movement of the paper P is restricted by the holding portion 47 when the paper is attached. It is detected that the detection lever 42 rotates toward the downstream side, the shielding portion 43 deviates from the optical axis of the lever rotation detection sensor 44, and the paper P remains between the fixing unit 12 and the holding portion 47. To be done.

  When the user inserts the fixing unit 12 after pulling it out, as shown in FIG. 15, when the amount of the leading edge of the jammed paper entering the fixing unit 12 is small, the lower portion of the fixing unit 12 to be inserted is located below the paper. After the fixing unit 12 is mounted, the front end of the sheet P is pressed to bend in the direction of the holding unit 47, and the front end of the sheet P is in contact with the frame 12b of the fixing unit 12 as shown in FIG.

At this time, the sheet detection lever 41 is stopped at the original position, and the shielding portion 43 remains shielding the optical axis of the lever rotation detection sensor 44, so that the remaining sheet P cannot be detected. ..
Therefore, in the present embodiment, when the fixing unit 12 is mounted after being pulled out and the lever rotation detection sensor 44 does not detect the residual of the paper P, the transport driving unit 38 causes the transfer unit 29 and the image forming unit 24. Is driven to push the paper P on the conveyor belt 11 toward the fixing unit 12.

  At this time, as shown in FIG. 17, the tip of the ejected paper P abuts on the upper portion of the holding portion 47, the tip is curved toward the paper abutting portion 41b of the paper detection lever 41, and is further extruded. Then, as shown in FIG. 18, the curved portion pushes the sheet contact portion 41b of the sheet detection lever 41, the sheet detection lever 41 is rotated toward the downstream side in the sheet conveyance direction, and the shielding portion 43 is rotated by the lever. The movement detection sensor 44 deviates from the optical axis, and it is detected that the sheet P remains between the fixing unit 12 and the transfer unit 29.

  The printing process including the jammed paper removing process by the printer 1 according to the present embodiment will be described below with reference to the flowchart shown in FIG.

  S1: When the printer 1 is powered on, the control unit 36 of the printer 1 controls the temperature of the heat belt 21 while controlling the fixing heater 21a according to the detected temperature output from the fixing temperature sensor 23 of the fixing unit 12. When the temperature of the heat belt 21 is raised and reaches a predetermined fixing temperature, the process proceeds to step S2 while maintaining the fixing temperature.

  S2: The controller 36, which has finished warming up the fixing unit 12, waits for reception of print data from a host device (not shown) such as a personal computer, waits for reception of print data, starts print processing when the print data is received, and then executes step S2. Move to. When the print data is not received, the waiting described above is continued.

  S3: The control unit 36 that has started the printing process feeds one sheet of the paper P in the paper cassette 3 to the paper feed path 2 by the paper feed unit 6, conveys the fed paper P to the registration roller pair 7, and skews the paper. The paper P is conveyed to the conveyor belt 11 by the registration roller pair 7 and the conveyor roller pair 9a at the timing synchronized with the toner image formation by each image forming unit 24, and the conveyor belt 11 forms the image forming units 24y and 24m. Pass under 24c and 24k in order.

At this time, the control unit 36 irradiates light corresponding to the image signal from the exposure head 27 to form an electrostatic latent image of each color on the photoconductor drum 26 of each image forming unit 24, and each photoconductor drum. Toner is attached to the electrostatic latent images of 26 to develop the toner images of the respective colors.
The developed toner images of the respective colors are sequentially transferred onto the paper by the transfer voltage applied from the power supply unit 39 to the transfer roller 28 when passing through the nip portion between the photosensitive drum 26 and the transfer roller 28, and the respective colors are transferred onto the paper. The toner image is transferred.

The sheet P on which the image is transferred is conveyed by the nip portion between the heat belt 21 and the pressure roller 22 of the fixing unit 12, and the toner is heated and melted by the heat belt 21 and the pressure roller 22 to fix the image, and the sheet P is fixed. The image is printed on P.
The printed paper P is transported by the transport roller pair 9b and the discharge roller pair 15 and discharged onto the discharge tray 4.

  In this way, the normal printing process by the printer 1 of this embodiment is executed.

  S4: During execution of the printing process, the control unit 36 monitors the occurrence of a jam while acquiring the outputs from the passage detection sensors 8, the discharge sensor 14, and the lever rotation detection sensor 44 of the paper detection unit 40. When it is determined that a jam has occurred, the pressing of the heat belt 21 and the heating roller 22 of the fixing unit 12 is released and the conveyance drive unit 38 stops the conveyance of the sheet P in order to start the jammed sheet removal processing. Then, the process proceeds to step S7. If no jam has occurred, the process proceeds to step S5.

  In this case, it is determined that a jam has occurred when the conveyance time of the leading edge of the paper P between the passage detection sensor 8, the discharge sensor 14, and the lever rotation detection sensor 44 exceeds the specified time. ..

  For example, if the conveyance time from the passage detection sensor 8b detecting the leading end of the conveyed paper P to the lever rotation detection sensor 44 detecting the leading end of the paper P is equal to or less than a prescribed time during this time, it is determined that there is no jam. If it is determined that the specified time is exceeded, it is determined that a jam has occurred between the passage detection sensor 8b and the lever rotation detection sensor 44.

  S5: When the control unit 36 waits for the discharge sensor 14 to detect the trailing edge of the printed paper P, and waits for the output of the discharge sensor 14, and recognizes the discharge of the paper P onto the discharge tray 4. To step S6. If the ejection of the printed paper P is not recognized, the process returns to step S3 to continue the printing process.

  S6: When the control unit 36, which has recognized the discharge of the paper P, has the next page in the received print data, returns to step S3 and executes the print processing of the next page. If the next page does not exist, the print process of this time is ended, and the process returns to step S2 to wait for reception of print data and wait.

  S7: The control unit 36 that has started the jam paper removal process opens the front cover such as the location of the jam on the display screen 5a of the operation display unit 5 such as "Open the front cover and remove the paper." The first sheet removal request screen displaying a message or the like requesting removal of the sheet is displayed to notify the remaining sheet removal method, and the parallel processing in steps S8 and S9 is started.

  S8: The control unit 36 that has started the parallel processing waits for the opening / closing detection sensor 32 to detect the opening of the front cover 31, and when the opening of the front cover 31 is detected, the process proceeds to step S10. When the opening of the front cover 31 is not detected, the parallel processing with step S9 is continued.

  S9: The control unit 36 that has started the parallel processing waits for the insertion / extraction detection sensor 35 to detect the pulling-out of the fixing unit 12, and when the pulling-out of the fixing unit 12 is detected, the process proceeds to step S12. When pulling out of the fixing unit 12 is not detected, the parallel processing with step S8 is continued.

  S10: The control unit 36, which has detected the opening of the front cover 31, waits until the insertion / removal detection sensor 35 detects the pulling out of the fixing unit 12, and when it detects the pulling out of the fixing unit 12, the process proceeds to step S12. .. When pulling out of the fixing unit 12 is not detected, the process proceeds to step S11.

  S11: The control unit waits until the opening / closing detection sensor 32 detects the closing of the front cover 31, and when detecting the closing of the front cover 31, the front cover 31 is closed after opening the front cover 31. That is, it recognizes that the jammed paper has been removed normally, and the process proceeds to step S21.

  When the closure of the front cover 31 is not detected, the process returns to step S10 and waits for the detection of the closure of the front cover 31 while monitoring the withdrawal of the fixing unit 12 in step S10.

  S12: The control unit 36, which has detected the pulling-out of the fixing unit 12, waits until the insertion / removal detection sensor 35 detects the mounting of the fixing unit 12, and when the mounting of the fixing unit 12 is detected, proceeds to step S13. .. When the mounting of the fixing unit 12 is not detected, the above standby is continued.

  In this step, if the opening of the front cover 31 is detected, the detection is ignored.

  S13: The control unit 36 which has detected the mounting of the fixing unit 12 confirms the output from the lever rotation detection sensor 44, and when the rotation of the paper detection lever 41 is detected, as shown in FIG. It is determined that the leading end portion of P has entered between the fixing unit 12 and the holding portion 47 and remains, and the process proceeds to step S14.

  When the lever rotation detection sensor 44 does not detect the rotation of the paper detection lever 41, that is, as shown in FIG. 16, there is residual paper, but the lever rotation detection sensor 44 stops at the original position. If so, the process proceeds to step S17.

  S14: The control unit 36, which has determined that the paper P that has entered between the fixing unit 12 and the holding unit 47 remains, says "Please remove the fixing unit and open the front cover to remove the paper" at the location of the jam. A second sheet removal request screen displaying a message to request removal of the sheet by pulling out the fixing unit and opening the front cover is displayed to notify the method of removing the remaining sheet, and the process proceeds to step S15. ..

  The user pulls out the fixing unit 12, opens the front cover 31, pulls out the jammed paper from the front side, attaches the fixing unit 12 to the original position, and closes the front cover 31.

  S15: The control unit 36 waits until the insertion / removal detection sensor 35 detects the mounting of the fixing unit 12, and when the mounting of the fixing unit 12 is detected, the control unit 36 proceeds to step S16. When the mounting of the fixing unit 12 is not detected, the above standby is continued.

  S16: The control unit 36 waits until the opening / closing detection sensor 32 detects the closing of the front cover 31, and when the closing of the front cover 31 is detected, the fixing unit 12 is mounted and the front cover 31 is closed. When it is recognized that the jammed paper that has entered between the frame 12b of the fixing unit 12 and the holding unit 47 has been removed, the process proceeds to step S21. When the closure of the front cover 31 is not detected, the above standby is continued.

  S17: The control section 36, which recognizes that the rotation of the sheet detection lever 41 is not detected although the remaining sheet exists, drives the transfer unit 29 and the image forming unit 24 by the transport driving section 38, and the transport belt 11 operates. Extrusion of the paper P toward the fixing unit 12 is started.

  S18: The control unit 36 that has started to push out the paper P by the transport belt 11 waits until the lever rotation detection sensor 44 detects the rotation of the paper detection lever 41, and as shown in FIG. When the curved portion of the paper P pushes the paper contact portion 41b of the paper detection lever 41, the lever rotation detection sensor 44 detects that the paper detection lever 41 has rotated, and it is determined that the residual paper has been detected. Then, the process proceeds to step S19.

  When the lever rotation detection sensor 44 does not detect the rotation of the paper detection lever 41, the above standby is continued.

  S19: The control unit 36, which has determined that the residual paper has been detected, opens the front cover on the display screen 5a of the operation display unit 5, such as the location of the jam, "Open the front cover and remove the paper." The first sheet removal request screen displaying a message or the like for requesting the removal of the sheet is displayed to notify the remaining sheet removal method, and the process proceeds to step S20.

  The user opens the front cover 31, pulls out the jammed paper from the front side, and closes the front cover 31.

  S20: The control unit 36 waits until the opening / closing detection sensor 32 detects the closing of the front cover 31, and when detecting the closing of the front cover 31, the front cover 31 is closed after opening the front cover 31. That is, it recognizes that the jammed paper remaining between the fixing unit 12 and the transfer unit 29 has been removed, and proceeds to step S21. When the closure of the front cover 31 is not detected, the above standby is continued.

  S21: The control unit 36 moved from step S11, S16, or S20 confirms the outputs from the passage detection sensors 8, the discharge sensor 14, and the lever rotation detection sensor 44, and all the sensors have not detected the paper P. In this case, it is determined that the jammed paper removing operation has been completed, and the process returns to step S3 to restart the printing process.

  If at least one of the sensors detects the paper P, it is determined that the jammed paper has not been removed, and the process returns to step S7 to display the first paper removal request on the display screen 5a of the operation display unit 5. Display the screen and restart the jam paper removal process.

  In this way, the printing process including the jammed paper removing process by the printer 1 of the present embodiment is executed.

  As described above, in the present embodiment, the paper detection lever 41 and the residual detection lever 42 are provided between the transport belt 11 of the transfer unit 29 and the nip portion between the heat belt 21 and the pressure roller 22 of the fixing unit 12. Since the paper detection unit 40 having the lever rotation detection sensor 44 for detecting these rotations is arranged, the paper is detected between the transfer unit 29 and the fixing unit 12 when the fixing unit 12 is inserted / removed in the jam paper removing operation. The remaining paper P can be easily detected.

Further, when a jam occurs, the display screen 5a of the operation display unit 5 notifies the remaining paper removal method according to the location of the jammed paper, so that the user can easily recognize the jammed paper removal method and easily perform the jam. It is possible to remove the paper, and it is possible to shorten the work time in the removal work when a jam occurs.
In the above-described embodiment, the case where the paper detection unit 40 is applied to the upstream side of the nip portion between the heat belt 21 and the pressure roller 22 of the fixing unit 12 has been described as an example. The same effect as above can be obtained.

Further, in the above-described embodiment, the case where the fixing unit 12 is provided so as to be insertable and removable has been described as an example, but it is a unit that has a conveying unit for conveying the paper P and is provided so as to be insertable and removable from the apparatus main body 1a. If so, it is applicable.
Further, in the above-described embodiment, the image forming apparatus is described as a printer that uses the four image forming units 24 and that transfers the toner image by the image forming unit 24 to a medium such as a sheet conveyed by the conveying belt 11. However, the image forming apparatus is not limited to the above, and may be a printer that transfers a toner image onto a medium through an intermediate transfer belt, a monochrome printer that uses one image forming unit 24, or two, three, or five or more image forming units 24. It may be a printer or the like used.
Further, in the above embodiments, the medium is described as a sheet of paper, but the medium is not limited to the above, and roll paper made of continuous paper may be cut paper or the like cut before reaching the conveyor belt 11. It may be.

1 Printer 1a Device Main Body 2 Paper Conveying Path 3 Paper Cassette 4 Ejection Tray 5 Operation Display Section 5a Display Screen 6 Paper Feeding Section 6a Pickup Roller 6b Paper Feeding Roller 6c Separation Roller 7 Registration Roller Pair 8, 8a-8c Passage Detection Sensor 9a, 9b, 18 Conveying roller pair 11 Conveying belt 11a Driving roller 11b Tension roller 12 Fixing unit 12a Fixing motor 12b Frame 13 Switching blade 14 Discharging sensor 15 Discharging roller pair 16a, 16b Conveying guide 17 Insertion / extraction guide 19 Front / reverse conveying path 21 Heat belt 21a Fixing heater 22 Pressure roller 23 Fixing temperature sensor 24, 24y, 24m, 24c, 24k Image forming unit 25 Toner cartridge 26 Photoconductor drum 27 Exposure head 28 Transfer roller 29 Transfer unit 31 Front cover 32 Open / close detection sensor 33 Top cover 34 Hook 35 Insertion / extraction detection sensor 36 Control section 37 Storage section 38 Transport drive section 39 Power supply section 40 Paper detection section 41 Paper detection lever 41a Rotation shaft 41b Paper contact section 42 Residual detection lever 43 Shield Part 44 Lever rotation detection sensor 45 Energizing spring 46 Locking part 47 Holding part 47a Notch part

Claims (6)

A first transport unit for transporting the medium,
A second transport unit that is disposed on the downstream side of the first transport unit in the medium transport direction and transports the medium delivered from the first transport unit;
A medium detection unit that is arranged between the first conveyance unit and the second conveyance unit and that detects the state of the medium between the first and second conveyance units;
An insertion / removal unit that is provided so that it can be inserted into and removed from the apparatus main body and that has the second transport section,
The medium detection unit includes a first lever that detects a medium conveyance state, a second lever that detects the presence or absence of a residual medium, and a lever rotation detection that detects rotation of the first and second levers. An image forming apparatus having a sensor. The image forming apparatus according to claim 1,
While projecting the first lever into the medium transport path, extending the second lever toward the upstream side of the medium transport path in the medium transport direction,
An image forming apparatus, wherein a holding plate having a cutout portion through which the tip end portion of the second lever passes is provided on the upstream side of the insertion / removal unit. The image forming apparatus according to claim 1, wherein:
An insertion / removal detection unit for detecting insertion / removal of the insertion / removal unit is provided,
An image forming apparatus, wherein when the insertion / removal detection unit detects insertion of the insertion / removal unit after withdrawal, the presence or absence of the residual medium is detected by an output from the lever rotation detection sensor. The image forming apparatus according to claim 3,
An image forming apparatus, which informs a method of removing the residual medium when the presence of the residual medium is detected by an output from the lever rotation detection sensor. The image forming apparatus according to claim 3,
When the presence of the residual medium cannot be detected by the output from the lever rotation detection sensor, the first transport unit is driven to detect the presence or absence of the residual medium again. apparatus. The image forming apparatus according to claim 5,
An image forming apparatus, which informs a method of removing the residual medium when the presence of the residual medium is detected after the driving of the first transport unit.

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