JP7091916B2 - Media transfer device and image forming device - Google Patents

Description

The present invention relates to an image forming apparatus for forming an image using an electrophotographic process and a medium transporting apparatus used for the image forming apparatus.

Conventionally, in an image forming apparatus that forms an image using an electrophotographic process, a medium on which an unfixed developer image is formed is passed through a fixing apparatus and heated and pressed to fix the developer image. As such an image forming apparatus, a heating and pressurizing method including a heating roller in which at least an elastic layer is coated on a cylindrical core metal and a heat source is arranged, and a pressurizing roller in contact with the heating roller to form a nip region. Fixing device is common.

In this regard, a sensor member is provided on the medium transport path, and measures are taken to detect the medium jam when the difference in the detection time of the sensor member exceeds a preset time.

For example, the patent document discloses an image forming apparatus in which a medium detection sensor is provided in a medium transfer path to determine a medium transfer state, and a medium jam is determined based on the detection time of the medium detection sensor (for example). , Patent Document 1).

Japanese Unexamined Patent Publication No. 2011-64837

However, when the medium remaining in the image forming apparatus is removed to release the medium jam, the medium detection sensor installed on the medium transport path becomes an obstacle. Therefore, the medium detection sensor may be caught when removing the residual medium.

The present invention has been made in view of such circumstances, and has a structure in which the medium detection sensor is retracted from the medium transport path and the tip of the medium detection sensor is protected from being caught when the medium jam is released. It is an object of the present invention to provide a medium transfer device and an image forming device having the above.

In order to solve the above problems, the medium transport device of the present invention has a first medium transport member that rotates and transports the medium to the medium transport path, and a nip region that comes into contact with the first medium transport member. A second medium transport member that is formed and sandwiches and transports the medium together with the first medium transport member, a housing that covers the medium transport path, and a medium transport path that is provided in a part of the housing. It has an opening / closing member for opening the medium, a lever member arranged on the medium transport path and swinging when the medium comes into contact with the medium, and a holding member for holding the lever member.
The lever member includes a contact portion and a tip portion with which the medium comes into contact, and a held portion that is swingably supported by the holding member.
Further, the opening / closing member comes into contact with the contact portion when the opening / closing member moves, and the lever member is retracted from the medium transport path. The contact portion provided closer to the nip region than the tip portion. To prepare for.
Then, when the opening / closing member is opened, the tip end portion of the lever member draws a first arcuate locus from the start point to the end point, and the contact portion of the opening / closing member draws a second arcuate locus from the start point to the end point. Draw an arc-shaped locus.
Further, the second arcuate locus is close to the medium transport path between the start point and the end point, and overlaps with the end point of the first arcuate locus at the end point.
Then, the opening / closing member, the lever member, and the contact portion are provided on the downstream side in the medium transport direction from the nip region.

According to the present invention, since the tip of the medium detection sensor is protected and retracted from the medium transport path when the medium jam is released, it is possible to prevent the medium from being caught by the medium detection sensor.

It is a schematic sectional drawing which shows the structure of the image forming apparatus of 1st Embodiment. It is a schematic sectional drawing which shows the structure of the fixing device of 1st Embodiment. It is a perspective view and the enlarged view of the front surface of the fixing device of 1st Embodiment. It is a perspective view and an enlarged view of the rear surface of the fixing device of 1st Embodiment. It is the whole view and the enlarged view of the lower gate attachment part of 1st Embodiment. It is a detailed figure of the lower guide of 1st Embodiment. It is an overall view of the medium detection sensor and the hook part at the time of opening the lower guide of 1st Embodiment. It is an overall view and the enlarged view of the installation of the medium detection sensor of 1st Embodiment. It is explanatory drawing which shows the state of the medium detection sensor and the sensor lever of 1st Embodiment. It is the rear view of the fixing device of 1st Embodiment, and the AA sectional view of the fixing device. It is explanatory drawing of the operation of the medium detection sensor and the hook part of 1st Embodiment. It is explanatory drawing of the medium detection sensor when the medium of 1st Embodiment is jammed. It is explanatory drawing of the jam release operation of the medium detection sensor and the hook part of 1st Embodiment. It is an overall view and the enlarged view of the installation of the medium detection sensor of the 2nd Embodiment. It is explanatory drawing which shows the state of the medium detection sensor and the sensor lever of 2nd Embodiment. It is the rear view of the fixing device of 2nd Embodiment, and the cross-sectional view of AA of the fixing device.

Hereinafter, examples of embodiments according to the present invention will be described with reference to the drawings. The same reference numerals are given to the elements common to the drawings.

The present invention is not limited to the following description, and can be appropriately modified without departing from the gist of the present invention.

Hereinafter, a printer as an image forming apparatus provided with a fixing device as a medium transporting device according to the present invention will be described.

FIG. 1 is a schematic cross-sectional view showing the configuration of the image forming apparatus according to the first embodiment. Incidentally, in the following, the right end portion in FIG. 1 is the front surface of the image forming apparatus 1000, and the vertical direction, the horizontal direction (main scanning direction), and the front-back direction (sub-scanning direction) when viewed facing the front surface are defined. Explained above. The image forming apparatus 1000 includes a fixing device 100, a medium 1001, a medium loading unit 1002, an ejection roller 1003, a paper feed cassette 1004, a resist roller 1005, an ejection port 1006, a developing apparatus 1010 (1010C, 1010M, 1010Y, 1010K), and a transfer. It has a device 1020.

The configuration of the image forming apparatus 1000 shown in FIG. 1 is an example, and if at least the fixing apparatus 100 is provided, some components may be omitted, added, or changed. good. For example, the image forming apparatus 1000 of this embodiment is configured to form a color image, but may be configured to form a monochromatic image.

The medium 1001 is a medium on which a developer image is formed.

The paper cassette 1004 houses the medium 1001 used for printing, and is detachably arranged in the lower part of the image forming apparatus 1000. Further, the paper feed cassette 1004 is housed in a state where the media 1001 are stacked inside, and is detachably attached to the lower part of the image forming apparatus 1000. The media 1001 housed in the paper cassette 1004 is fed out one by one from the uppermost portion by a pickup roller (not shown) provided on the upper portion of the paper cassette 1004, travels along the medium transport path, and a developing device is arranged. It is conveyed to the image forming unit.

The resist roller 1005 sends the medium 1001 fed one by one from the paper cassette 1004 to the transfer device 1020 at the timing of development.

The developing apparatus 1010 (1010C, 1010M, 1010Y, 1010K) is an apparatus for forming a developer image. In this embodiment, each developing apparatus 1010 (1010C, 1010M, 1010Y, 1010K) develops each color of cyan (C), magenta (M), yellow (Y), and black (K), respectively. Hereinafter, the details of the developing apparatus 1010 will be described.

The developing device 1010 includes a photosensitive drum 1011, a charging device 1012, an exposure device 1013, a developer container 1014, and a cleaning member 1015.

Although the detailed configuration of only the developing device 1010C is shown, the developing device 1010M, the developing device 1010Y, and the developing device 1010K also have the same configuration.

The surface of the photosensitive drum 1011 is uniformly charged by the charging device 1012, and further selectively exposed by the exposure device 1013 to form an electrostatic latent image on the surface. The photosensitive drum 1011 is an example of an electrostatic latent image carrier. As the electrostatic latent image carrier, not only a drum shape (photosensitive drum 1011) but also a belt shape may be applied.

The developer container 1014 accommodates the developer. The developer container 1014 is configured to be removable from the developing device 1010. A shutter member (not shown) is provided at the bottom of the developer container 1014. The shutter member can be opened and closed, and the developer contained in the developer container 1014 is supplied to the developing device 1010. On the other hand, the developing apparatus 1010 is provided with a developing agent receiving opening for receiving the developing agent supplied from the developing agent container 1014. Therefore, when the shutter member is opened after the developer container 1014 is mounted on the developing apparatus 1010, the developing agent naturally drops through the developing agent receiving opening, so that the developing agent is supplied to the inside of the developing apparatus 1010. To. The developer supplied to the developer 1010 develops an electrostatic latent image formed on the surface of the photosensitive drum 1011 to form a developer image.

The cleaning member 1015 is a device for transferring the developer image to the medium 1001 and then scraping and discarding the developer remaining on the surface of the photosensitive drum 1011.

The transfer device 1020 is arranged so as to be in pressure contact with the photosensitive drum 1011 of the developing device 1010, and is a belt type that transfers the developer image on the surface of the photosensitive drum 1011 to the medium 1001 by applying a voltage. It is a device. The transfer device 1020 is driven by rollers 1022 and rollers 1023 on which the endless transfer medium 1021 is stretched.

The fixing device 100 is a device that fixes the developer image formed on the medium 1001 to the medium 1001 by the transfer device 1020.

The discharge roller 1003 discharges the medium 1001 on which the developer image is fixed from the discharge port 1006 to the medium loading unit 1002.

The medium loading unit 1002 is a place where the printed medium 1001 is loaded.

The image forming apparatus 1000 having the above-described configuration operates as follows, for example. First, when the image forming apparatus 1000 receives a printing command from a higher-level device (not shown) such as a personal computer (PC), the medium 1001 is transferred from the paper feed cassette 1004 to the resist roller 1005 by rotation of a pickup roller (not shown). It is conveyed and conveyed to the transfer device 1020 by the resist roller 1005. At this time, for example, in the developing device 1010C, the surface of the photosensitive drum 1011C is charged by the charging device 1012C as the photosensitive drum 1011C rotates in the rotation direction a. Then, in the developing apparatus 1010C, the exposure apparatus 1013C is exposed according to the image information included in the printing command, so that an electrostatic latent image corresponding to the image information is formed, and this electrostatic latent image is used as a developing agent. It is developed by the developer supplied by the container 1014C, and a developer image is formed on the photosensitive drum 1011C. The developer image formed on the photosensitive drum 1011C is transferred onto the medium 1001 conveyed on the transfer device 1020 in the transfer direction b, and the developer remaining on the photosensitive drum 1011C after the transfer is removed by the cleaning member 1015C. After being scraped off and the photosensitive drum 1011C is cleaned, it is subjected to the next charging. In the developing device 1010M, the developing device 1010Y, and the developing device 1010K, development is executed in the same process as the developing device 1010C.

While the medium 1001 is conveyed in the transfer direction b by the transfer device 1020, the developing agent images of black, yellow, magenta, and cyan are transferred in order, and all the developing agent images necessary for image formation indicated by the above image information are transferred. After that, it is transferred from the transfer device 1020 to the fixing device 100. The fixing device 100 fixes the developer image on the medium 1001 by passing through the nip region of the heating belt 10 and the pressure roller 9 arranged so as to face each other across the medium transport path U (details will be described later). Hand over further to the rear.

A discharge roller 1003 is arranged behind the fixing device 100. Similar to the resist roller 1005, the discharge roller 1003 transports the medium 1001 delivered from the fixing device 100 backward and upward by appropriately rotating a guide for guiding the medium 1001 and a plurality of transport rollers, and then turns back toward the front. (Transfer direction c), the image is conveyed to the medium loading unit 1002 formed on the upper surface of the image forming apparatus 1000.

Next, the configuration of the fixing device 100 will be described. As shown in a schematic cross-sectional view in FIG. 2, the fixing device 100 is roughly divided into a front cover 1 and a rear cover 5 formed so as to surround the whole, a heating belt 10 arranged on the upper side of the medium transport path U, and a heating belt 10. It is composed of a pressure roller 9 arranged under the medium transport path U. Further, the fixing device 100 is provided with an inlet side medium detection lever 2 for detecting that the medium 1001 has entered the nip region. Further, a discharge side medium detection sensor lever 7 for detecting that the medium 1001 has been discharged from the nip region is provided.

The front cover 1 and the rear cover 5 (FIG. 2) have a rectangular parallelepiped shape as a whole, and the heating belt 10 and the pressure roller 9 are respectively formed in the portions largely hollowed out so as to penetrate the central portions of the front and rear surfaces thereof in the front-rear direction. It has been incorporated. Further, on the left and right side surfaces of the front cover 1 and the rear cover 5, a plurality of holes such as an insertion hole for inserting a part of the heating belt 10 and a shaft hole for rotatably supporting the pressure roller 9 are provided. Is appropriately drilled.

The heater 105 is formed in a rectangular parallelepiped shape that is long in the left-right direction as a whole, and when a current is supplied to the heater 105, heat is generated according to the magnitude of the current to generate heat in the heating belt 10. The heater 105 is supplied with power from the outside via, for example, a connector (not shown). The type of the heater 105 is not particularly limited, but is, for example, a planar heater or the like.

The heating belt 10 is a cylindrical endless belt made of a heat-resistant material, which is heated by the heat generated in the heater 105. The heating belt 10 rotates in a certain direction (R2) while being heated by the heater 105. Each of the heater support member 101, the holder heater 102, the temperature sensor 103, the heat conduction member 104, the heater 105, and the heat diffusion member 106 is arranged inside, for example, the ring-shaped heating belt 10.

The temperature sensor 103 is a sensor that detects the heating temperature of the heater 105. A heat conductive member 104 is arranged between the heater 105 and the temperature sensor 103. Therefore, the temperature sensor 103 detects the temperature of the heater 105 via the heat conductive member 104.

The heat conductive member 104 is arranged between the heater 105 and the temperature sensor 103, and is a plate-shaped member that conducts the heat generated in the heater 105 to the temperature sensor 103. That is, the heat conductive member 104 is in contact with each of the heater 105 and the temperature sensor 103. The heat conductive member 104 is, for example, a metal plate made of stainless steel (SUS).

The heat diffusion member 106 is arranged between the heater 105 and the heating belt 10, and is a plate-shaped member that conducts the heat generated in the heater 105 to the heating belt 10. The heat diffusion member 106 is, for example, a metal plate made of stainless steel (SUS).

The pressure roller 9 and the heating belt 10 are arranged so as to face each other, and a nip portion N is formed because pressure is applied between the pressure roller 9 and the heating belt 10. The pressure roller 9 rotates in the direction of arrow R1 by a driving force (not shown). Further, the heating belt 10 is configured to drive and rotate in the direction of arrow R2 due to friction with the heating roller 9.

When the pressurizing roller 9 rotates in the direction of arrow R1 at the nip portion N by supplying a driving force from a motor (not shown), the fixing device 100 causes a frictional force to act between the pressing roller 9 and the heating belt 10. The heating belt 10 can be rotated (circulated) in the direction of arrow R2. At this time, the fixing device 100 can apply heat and pressure to the medium 1001 as long as the medium 1001 is transported along the medium transport path U.

Subsequently, the detailed configuration of the medium emission detection sensor of the fixing device 100 according to the first aspect of the present invention will be described below.

FIG. 3 is a perspective view and an enlarged view of the front surface of the fixing device 100. The front cover 1 constitutes the exterior of the front surface of the fixing device, and the inlet-side medium detection lever 2 for detecting that the medium has entered the fixing device is provided at the center position in the longitudinal direction of the medium inlet 3 which is the entrance to the fixing device. ing.

FIG. 4 is a perspective view and an enlarged view of the rear surface of the fixing device 100. The lower guide 4, the rear cover 5, and the lower cover 6 constitute the exterior of the rear surface of the fixing device 100. Further, a medium described later will be described in the longitudinal direction of the discharge side medium detection sensor lever 7 for detecting that the medium has been discharged from the fixing device 100, the medium discharge port 11 for discharging the medium 1001 from the fixing device 100, and the medium discharge port 11. An upper guide 12 in which the transport guides 4b (FIG. 6) are lined up is provided on the exterior of the fixing device 100. A discharge-side medium detection sensor lever 7 is provided at the center position in the longitudinal direction of the medium discharge port 11, and the discharge-side medium detection sensor lever central portion 7ab and tip portion 7aj are provided in order to detect the passage of the medium 1001. It is provided in the medium transport path U.

5A and 5B are an overall view (a) of the lower guide 4 from the rear surface of the fixing device when the rear cover 5 is removed, and enlarged views (b) and (c) of the left and right mounting portions of the fixing device 100. In order to prevent damage due to opening and closing of the lower guide 4, the lower guide 4 is attached to the lower guide holding member 15 made of metal. The post 15L and the post 15R, which are a part of the lower guide holding member 15, are attached to a shaft portion (not shown) of the metal frame 14 to form a fulcrum C. The torsion spring 16a and the torsion spring 16b are attached to the shaft portion and have an urging force that can be manually opened in the direction of arrow T.

The lower guide 4 is an opening / closing member as a cover member that also serves as an exterior cover, and can be manually opened to the rear surface side of the fixing device 100 by rotating around the fulcrum C of the lower guide holding member 15 attached to the lower guide 4. There is. The lower guide 4 is opened when a medium jam occurs or when maintenance is performed.

FIG. 6 is a detailed view of the lower guide 4 when the lower guide 4 is opened. A medium transport guide 4b for transporting the passed medium 1001 from the fixing device 100 to the medium loading section 1002, a medium transport guide tip portion 4a, a hook portion 4c provided at the center portion in the longitudinal direction of the lower guide 4, and the hook portion 4c. A support member 4e connected to each of the left and right end portions of the above, and a gap portion 4d formed by the support member 4e and the hook portion 4c.

A gap 4d is provided in the central portion in the longitudinal direction at the same position as the discharge side medium detection sensor lever 7 so that the discharge side medium detection sensor lever 7 and the lower guide 4 do not come into contact with each other except when the lower guide 4 is opened. .. At this time, the hook portion 4c and the gap portion 4d are attached to the central portion in the longitudinal direction of the lower guide 4 in order to align with the position of the discharge side medium detection sensor lever 7.

FIG. 7 is a perspective view (a) and an enlarged view (b) of the rear surface of the fixing device 100 after the lower guide 4 is opened. When the lower guide 4 is opened, the hook portion 4c provided at the center of the lower guide 4 in the longitudinal direction, which rotates around the fulcrum C (FIG. 5), comes into contact with the discharge side medium detection sensor lever 7 and the discharge side medium detection sensor. The lever 7 is retracted from the medium transport path U. At this time, the hook portion 4c contacts and protects the discharge side medium detection sensor lever tip portion 7aj.

FIG. 8 is an overall view and an enlarged view of mounting the medium detection sensor on the rear surface of the fixing device, and FIG. 9 is an explanatory view showing a state of the medium detection sensor and the sensor lever. The mechanism for detecting the transport state of the medium 1001 includes a discharge-side medium detection sensor lever 7 and a medium detection sensor 8 attached to the metal frame 14. Note that FIG. 9 shows a state in which the discharge side medium detection sensor lever 7 and the medium detection sensor 8 shown in FIG. 8 are viewed from the front surface direction to the rear surface direction for convenience of explanation.

The medium detection sensor 8 is a so-called optical sensor, and the sensor detection unit 8a provided with the light emitting unit and the light receiving unit is arranged so as to intersect the medium transport path U (FIG. 7), and the detection result by the light receiving unit is shown. Not supplying to the control unit. The control unit recognizes the transport state of the medium 1001 based on the detection result acquired from the medium detection sensor 8, and also recognizes the size of the medium 1001, that is, the length in the direction along the medium transport path U. do.

The discharge side medium detection sensor lever 7 shields the discharge side medium detection sensor lever tip portion 7aj, the discharge side medium detection sensor lever center portion 7ab, the mounting shaft 7ac of the discharge side medium detection sensor lever 7, and the sensor detection unit 8a from light. It is composed of a sensor light-shielding portion 7ad, a discharge-side medium detection sensor lever base portion 7af, and a discharge-side medium detection sensor lever supported portion 7ag. The discharge side medium detection sensor lever 7 is in contact with the metal frame 14a portion at the discharge side medium detection sensor lever contact portion 7ai by the urging force of the spring 13a described later. Further, it is composed of an end portion 13ab of the spring 13a in contact with the metal frame 14 and an end portion 13ac of the spring 13a for engaging the sensor light-shielding portion 7ad.

On one end side of the discharge side medium detection sensor lever 7, the discharge side medium detection sensor lever central portion 7ab to which the conveyed medium 1001 abuts and the discharge side medium detection sensor to protect by contacting the hook portion 4c after the lower guide 4 is opened. A lever tip portion 7aj is provided, and a discharge side medium detection sensor lever base portion 7af is provided on the other end side. The discharge side medium detection sensor lever root portion 7af is provided with two discharge side medium detection sensor lever supported portions 7ag. One end side of the discharge side medium detection sensor lever supported portion 7ag is provided in a direction orthogonal to the discharge side medium detection sensor lever root portion 7af. Of the two discharge-side medium detection sensor lever supported portions 7ag, one is provided with only the mounting shaft 7ac of the discharge-side medium detection sensor lever 7 that is rotatably supported, and the other is a sensor light-shielding portion 7ad. A mounting shaft 7ac of the spring 13a and the discharge side medium detection sensor lever 7 is provided. The attachment shaft 7ac of the discharge-side medium detection sensor lever 7 is attached to the metal frame 14 to form a fulcrum A. Further, the discharge side medium detection sensor lever 7 is rotatable around the fulcrum A.

The end portion 13ac of the spring 13a applies an urging force to the sensor light-shielding portion 7ad in the direction of the arrow X'by the repulsive force of the end portion 13ab of the spring 13a in contact with the metal frame 14. Therefore, the sensor light-shielding unit 7ad and the discharge-side medium detection sensor lever 7 do not rotate due to their own weight, and it is possible to maintain a normal state of light-shielding between the sensor detection unit 8a of the medium detection sensor 8. Further, since the discharge side medium detection sensor lever contact portion 7ai is pressed against the metal frame 14a portion by the urging force in the direction of the arrow X', the discharge side medium detection sensor lever shown in FIG. 9B to be described later is shown. It is provided so as not to rotate in the X'direction from the position of 7.

10A and 10B are a rear view (a) of the fixing device 100, an AA cross-sectional view (b) of the fixing device 100 when the medium 1001 is not passed, and an AA sectional view of the fixing device 100 during the passing of the medium. (C), FIG. 11 is a cross-sectional view taken along the line AA of the fixing device 100 when a medium jam occurs.

When the sensor light-shielding unit 7ad is located at the position shown in FIG. 10B without the medium 1001 passing through the paper, the sensor light-shielding unit 7ad shields light between the light-emitting unit and the light-receiving unit of the sensor detection unit 8a. At this time, the medium 1001 passing through the medium transport path U is determined by the control unit to be in a non-passing state. Further, as described above, since the end portion 13ac of the spring 13a applies an urging force to the sensor shading portion 7ad in the direction of the arrow X', the state of FIG. 10B can be maintained.

On the other hand, when the medium 1001 has the sensor light-shielding portion 7ad at the position shown in FIG. 10C in the paper, the sensor light-shielding portion 7ad does not exist between the light-emitting portion and the light-receiving portion of the sensor detection unit 8a. At this time, the medium 1001 passing through the medium transport path U is determined by the control unit to be in the paper passing state. Further, as will be described later, when the discharge side medium detection sensor lever 7 is pushed down by the medium 1001, the discharge side medium detection sensor lever 7 rotates in the direction of the arrow X. At this time, the state shown in FIG. 10C is maintained while the medium 1001 is passing through the paper.

Next, the media passing operation of the discharge side medium detection sensor lever 7 and the medium detection sensor 8 will be described with reference to FIG.

As described above, the engaging portion between the metal frame 14 and the mounting shaft 7ac of the discharge side medium detection sensor lever 7 is rotatably provided as the fulcrum A. Therefore, when the medium 1001 conveyed from the arrow V direction comes into contact with the discharge side detection sensor lever central portion 7ab and the tip portion 7aj, it is pushed down and the discharge side medium detection sensor lever 7 rotates in the arrow X direction. Along with the rotation of the discharge side medium detection sensor lever 7, the sensor light-shielding portion 7ad rotates in the direction of the arrow X with the fulcrum A as the axis, so that the sensor light-shielding portion 7ad is separated from the sensor detection portion 8a of the medium detection sensor 8. Therefore, it is detected that the medium 1001 is passing by detecting the light from the light emitting unit of the sensor detection unit 8a by the light receiving unit without being shielded by the sensor light shielding unit 7ad. After passing through the medium 1001, the sensor light-shielding unit 7ad returns to the normal state of light-shielding the sensor detection unit 8a due to the urging force of the spring 13a.

Next, the medium-passing operation of the discharge-side medium detection sensor lever 7 before and after the paper-passing of the medium 1001 will be described with reference to FIG.

When the medium 1001 has not reached the discharge side medium detection sensor lever 7, the discharge side detection sensor lever central portion 7ab and the tip portion 7aj protrude into the medium transport path U as shown in FIG. 10 (b). ing.

After that, when the medium 1001 passes through the nip portion N of the fixing device 100, the discharge side medium detection sensor lever 7 rotates in the direction of arrow X and slips under the medium 1001 as shown in FIG. 10 (c). At the same time, the sensor shading portion 7ad also rotates in the direction of the arrow X, and the metal frame 14a portion and the discharge side medium detection sensor lever contact portion 7ai are separated from each other. As a result, the sensor light-shielding unit 7ad does not exist between the light-emitting unit and the light-receiving unit of the sensor detection unit 8a. Therefore, the control unit determines that the medium 1001 is in the paper-passing state. At this time, since the discharge side medium detection sensor lever 7 rotates in the arrow X direction, the urging force of the spring 13a is set to be weaker than the force applied from the arrow V direction due to the passage of the medium 1001.

In the case where the medium jam has not occurred, the discharge side medium detection sensor lever 7 is pushed down by the medium 1001 until the medium 1001 has passed over the discharge side medium detection sensor lever 7 as shown in FIG. 10 (c). Maintain the state.

Then, when the medium 1001 finishes passing on the discharge side medium detection sensor lever 7, the discharge side medium detection sensor lever 7 is rotated in the direction of the arrow X'with the fulcrum A as an axis by the urging force of the spring 13a to be the original. The position returns to the position shown in FIG. 10 (b), which is the state. At this time, the metal frame 14a portion and the discharge side medium detection sensor lever contact portion 7ai come into contact again.

Next, the medium jam release operation of the hook portion 4c of the lower guide 4 and the discharge side medium detection sensor lever 7 when the medium jam occurs will be described.

FIG. 11 is a cross-sectional view of the fixing device 100 illustrating the operation of the discharge side medium detection sensor lever 7 and the hook portion 4c of the lower guide 4 after the lower guide 4 is opened, and FIG. 13 is a bellows-shaped lower guide 4 when the medium is jammed. It is explanatory drawing which shows the state of the discharge side medium detection sensor lever 7 at the time of opening.

As shown in FIG. 11, when the medium 1001 opens the lower guide 4 by a medium jam or the like, the hook portion 4c moves by drawing a rotation locus Z from the start point Z1 to the end point Z2 about the fulcrum C as an axis. The rotation locus Z at this time is an arc locus drawn by the hook portion 4c rotating around the fulcrum C. Similarly, the central portion 7ab and the tip portion 7aj of the discharge side medium detection sensor lever move while drawing a rotation locus Y from the start point Y1 to the end point Y2 about the fulcrum A. The rotation locus Y at this time is an arc locus drawn by the discharge side medium detection sensor lever tip portion 7aj rotating around the fulcrum A.

At this time, by providing the discharge side medium detection sensor lever center portion 7ab and the tip portion 7aj on the rotation locus Z reaching the start point Z1 and the end point Z2, the hook portion 4c is located at the center of the discharge side medium detection sensor lever while the lower guide 4 is open. It becomes possible to retract the discharge side medium detection sensor lever 7 from the medium transport path U (FIG. 10 (b)) in contact with the portion 7 ab. At this time, the fulcrum C is provided at a position farther from the fulcrum A to the medium transport path U and closer to the medium discharge port 11. Further, the position of the fulcrum A and the radius of the rotation locus Y, the position of the fulcrum C, and the radius of the rotation locus Z are provided so that the end point Y2 of the rotation locus Y and the end point Z2 of the rotation locus Z overlap. There is. That is, the hook portion 4c that was in contact with the discharge side medium detection sensor lever central portion 7ab during the opening of the lower guide 4 moves to the discharge side medium detection sensor lever tip portion 7aj after the lower guide 4 is opened. This is because the end point Y2 and the end point Z2 are provided at overlapping positions.

As a result, after the lower guide 4 is opened, the hook portion 4c comes into contact with the discharge side medium detection sensor lever tip portion 7aj. At this time, the vertical positional relationship between the hook portion 4c of the end point Z2 and the discharge side medium detection sensor lever tip portion 7aj of the end point Y2 is such that the hook portion 4c overlaps the discharge side medium detection sensor lever tip portion 7aj from above. Contact. Therefore, since the medium 1001 passing through the medium transport path U does not come into contact with the discharge side medium detection sensor lever tip 7aj, it is possible to protect the discharge side medium detection sensor lever tip 7aj from being caught by the medium 1001. Become.

In order to open the lower guide 4, the urging force of the spring 13a is set to be weaker than the force applied by the hook portion 4c in contact with the central portion 7ab and the tip portion 7aj of the discharge side medium detection sensor lever.

As shown above, when the medium jam is released from the rear surface of the fixing device 100, the hook portion 4c of the lower guide 4 is discharged in the process of taking out the fixing device 100 from the image forming device 1000, opening the lower guide 4, and then taking out the medium 1001. The discharge side medium detection sensor lever 7 is retracted from the medium transport path U in contact with the side medium detection sensor lever central portion 7ab. Further, after the lower guide 4 is opened, the hook portion 4c of the lower guide 4 comes into contact with the discharge side medium detection sensor lever tip portion 7aj. That is, the media detection sensor 8 is retracted from the medium transport path U, and the discharge side medium detection sensor lever tip portion 7aj is protected. As a result, the medium 1001 is less likely to be caught on the discharge side medium detection sensor lever tip 7aj.

FIG. 12 is an explanatory diagram of the discharge side medium detection sensor lever 7 when the medium 1001 is jammed in a bellows shape, and FIG. 13 is an explanatory diagram of the discharge side medium detection sensor lever 7 when the bellows-shaped medium 1001 is released. It is explanatory drawing of the operation of the lower guide 4.

The mountain-folded portion of the bellows-shaped medium 1001 may be caught on the discharge side medium detection sensor lever tip 7aj, and the jammed medium 1001 may be present on the rotation locus Z.

At this time, since the apex Z'of the locus exists above the start point Z1 position and the end point Z2 position of the rotation locus Z, the hook portion 4c of the lower guide 4 pushes the bellows-shaped medium 1001 upward. It becomes possible. At the same time, the hook portion 4c of the lower guide 4 hooks the central portion 7ab of the discharge side medium detection sensor lever with the hook portion 4c of the lower guide 4, and retracts the discharge side medium detection sensor lever 7 from the medium transport path U while drawing a rotation locus Y. .. At that time, the hook portion 4c moves from the discharge side medium detection sensor lever central portion 7ab to the discharge side medium detection sensor lever tip portion 7aj. That is, since the hook portion 4c of the lower guide 4 pushes the medium 1001 away, even if the medium jam occurs in a bellows shape, the jam release of the discharge side medium detection sensor lever tip portion 7aj remains good.

As described above, according to the fixing device 100 of the first aspect, when the lower guide 4 as the fixing device cover that also serves as the medium guide for releasing the jam is opened, the discharge side protruding into the medium transport path U. The media detection sensor lever tip 7aj is protected by the hook portion 4c of the lower guide 4, and is retracted from the media transport path U. As a result, it is possible to prevent the discharge side medium detection sensor lever 7 from being caught by the medium 1001. Further, even when a jam in which the medium 1001 is folded in a bellows shape occurs on the rotation locus Z of the hook portion 4c, the medium 1001 is pushed away by the hook portion 4c of the lower guide 4, so that the medium 1001 detects the discharge side medium. It is possible to prevent the sensor lever 7 from being caught.

As shown in FIGS. 14, 15, and 16, as a second embodiment, the discharge side medium detection sensor lever 7 is composed of two members, a sensor lever 7a and a sensor lever 7b.

Since other configurations and operations are the same as the configurations of the image forming apparatus 1000 of the first embodiment, detailed description thereof will be omitted for the sake of simplification.

FIG. 14 is an overall view and an enlarged view of mounting of the discharge side medium detection sensor lever 7 at the rear portion of the fixing device 100 as the second embodiment, and FIG. 15 is an enlarged view of the medium detection sensor 8 and the discharge side medium detection sensor lever 7. 16 is a state diagram, FIG. 16 is a rear view (a) of the fixing device 100 of the second embodiment, an AA cross-sectional view (b) of the fixing device 100 when the medium 1001 is not passed, and a medium jam. 11 is a cross-sectional view taken along the line AA of the fixing device 100 when the medium 1001 is removed from the medium inlet 3 of the fixing device 100. Note that FIG. 15 shows a state in which the discharge side medium detection sensor lever 7 and the medium detection sensor 8 shown in FIG. 14 are viewed from the front surface direction to the rear surface direction for convenience of explanation.

The end portion 13ac of the spring 13a applies an urging force to the sensor light-shielding portion 7ad in the direction of the arrow X'by the repulsive force of the end portion 13ab of the spring 13a in contact with the metal frame 14. Therefore, the sensor light-shielding unit 7ad and the discharge-side medium detection sensor lever 7 do not rotate due to their own weight, and it is possible to maintain the normal state of light-shielding the sensor detection unit 8a. Further, the discharge side medium detection sensor lever contact portion 7ai is pressed against the metal frame 14a portion by the urging force in the direction of the arrow X'. Therefore, the position of the sensor lever 7a is provided so as not to rotate in the X'direction from the position shown in FIG. 16B.

The engaging portion of the mounting shaft 7ac of the discharge side medium detection sensor lever 7 is mounted so as to rotate around the metal frame 14 and the fulcrum A. Therefore, the discharge side medium detection sensor lever 7 also rotates around the fulcrum A on the metal frame 14. A fulcrum B is formed by fitting a concave portion (not shown) of the sensor lever 7a and a convex portion (not shown) of the sensor lever 7b. Further, the sensor lever 7b can rotate about the fulcrum B with respect to the sensor lever 7a. Further, a spring 13b is attached to the sensor lever 7a and the sensor lever 7b.

The end portion 13ba of the spring 13b is in contact with the sensor lever protrusion 7c to have an urging force in the direction of the arrow W, and the sensor lever 7b and the sensor lever 7a are in contact with each other at the contact portion 7ae. The sensor lever 7b is configured not to rotate about the fulcrum B by its own weight due to the urging force. Further, the spring 13a is attached so that the discharge side medium detection sensor lever 7 and the sensor shading portion 7ad do not rotate around the fulcrum A due to their own weight.

Next, the medium jam release operation of the discharge side medium detection sensor lever 7 and the medium detection sensor 8 will be described with reference to FIG.

When the medium 1001 conveyed from the direction of arrow V comes into contact with the sensor lever 7b, the sensor lever 7b is pushed down by the medium 1001 and rotates in the direction of arrow X with the fulcrum A as an axis. Along with the rotation of the discharge side medium detection sensor lever 7, the sensor light-shielding portion 7ad is separated from the sensor detection portion 8a of the medium detection sensor 8 by rotating in the arrow X direction about the fulcrum A as an axis. Therefore, it is detected that the medium 1001 is passing by detecting the light from the light emitting unit of the sensor detection unit 8a by the light receiving unit without being shielded by the sensor light shielding unit 7ad. After passing through the medium 1001, the sensor light-shielding unit 7ad returns to the state of light-shielding the sensor detection unit 8a due to the urging force of the spring 13a. The urging force of the spring 13a is set to be weaker than the force applied from the arrow V direction due to the passage of the medium 1001.

FIG. 16 describes a medium jam release operation of the discharge side medium detection sensor lever 7 when the medium 1001 is removed from the medium inlet 3 in the front direction. When the medium 1001 is pulled from the medium inlet 3 to release the medium jam, it is provided so as not to rotate in the X'direction from the position of the sensor lever 7a as described above (FIG. 16 (b)). Therefore, the contact portion 7ae of the sensor lever 7a and the sensor lever 7b are separated from each other, and only the sensor lever 7b rotates in the direction of the arrow W'with respect to the fulcrum B ((c) in FIG. 16). As a result, the jam medium is less likely to be caught by the sensor lever 7b by retracting to the position of the sensor lever 7b shown in black.

Then, when the medium 1001 is removed and the medium jam is released, the sensor lever 7b shown in white is painted by the urging force of the end portion 13ba of the spring 13b in contact with the sensor lever protrusion 7c in the arrow W direction. The position returns ((b) in FIG. 16). Therefore, the discharge side medium detection sensor lever 7 is projected again to the position of the medium transfer path U.

As described above, according to the image forming apparatus of the second embodiment, the discharge side medium detection sensor lever 7 is attached to the sensor lever 7b (first member) at the tip and the sensor lever 7a (second member) at the root. By making the first member 7b rotatable with respect to the second member 7a, the medium 1001 is pulled toward the front surface of the fixing device 100, and even when the medium jam is released, the medium 1001 protrudes into the medium transport path U. The sensor lever 7b that has been used can be retracted from the medium transport path U. That is, it is possible to more reliably prevent the sensor lever 7b from being caught in the medium 1001.

In the above embodiment, as a part of an image forming apparatus (printer) in which a medium transport path, a paper detecting means, and a lower guide that also serves as an exterior cover are used, a portion of the fixing device downstream in the medium transport direction is taken as an example. As described above, it can be applied to other places of the printer as long as the medium transport path is formed.

The present invention relates to a fixing unit provided in an image forming apparatus such as a color electrophotographic printer, a monochrome electrophotographic printer, a multifunction printer, a facsimile, a multifunction device, a copying machine, and the color electrophotographic printer or monochrome. It can be used for image forming devices such as electrophotographic printers, multifunction printers, facsimiles, multifunction devices, and copiers.

1 Front cover 2 Inlet side media detection sensor lever 3 Media inlet to the fixing device 4 Lower guide 5 Rear cover 6 Lower cover 7 Discharge side media detection sensor lever 8 Medium detection sensor 9 Pressurizing roller 10 Heating belt 11 Media discharge port to the fixing device 12 Upper guide 13a Spring 14 Metal frame 15 Lower guide holding member 1001 Medium

Claims (9)

A first medium transport member that rotates and transports the medium to the medium transport path,
A second medium transporting member that contacts the first medium transporting member to form a nip region and sandwiches and transports the medium together with the first medium transporting member.
A housing that covers the medium transport path and
An opening / closing member provided in a part of the housing and opening the medium transport path,
A lever member that is arranged on the medium transport path and swings when the medium comes into contact with the medium.
It has a holding member that holds the lever member, and has
The lever member includes a contact portion and a tip portion with which the medium comes into contact, and a held portion that is swingably supported by the holding member.
The opening / closing member includes a contact portion provided closer to the nip region than the tip portion, which abuts the contact portion when the opening / closing member moves and retracts the lever member from the medium transport path. ,
When the opening / closing member is opened, the tip end portion of the lever member draws a first arcuate locus from the start point to the end point, and the contact portion of the opening / closing member draws a second arcuate shape from the start point to the end point. Draw the trajectory of
The second arc-shaped locus is close to the medium transport path between the start point and the end point, and overlaps with the end point of the first arc-shaped locus at the end point.
A medium transport device comprising the opening / closing member, the lever member, and the contact portion on the downstream side in the medium transport direction with respect to the nip region. The opening / closing member is engaged with a part of the housing by a rotatable central shaft, and the opening / closing member is engaged with a part of the housing.
With the rotation of the opening / closing member, the contact portion draws the second arc-shaped locus, approaches the medium transport path from the inside of the housing, and moves to the outside of the housing. The medium transfer device according to claim 1. The opening / closing member has two support members extending in a direction orthogonal to the central axis.
The medium transfer device according to claim 2, wherein the contact portion is formed so as to extend between the end portions of the two support members. The medium transfer device according to claim 3, wherein the contact portion comes into contact with the contact portion when the contact portion moves from the inside of the housing to the outside of the housing. The contact portion and the held portion are each composed of separate members, the held portion pivotally supports the rotation shaft of the contact portion, and the contact portion rotates with respect to the held portion. The medium transfer device according to claim 1, wherein the medium transfer device is characterized in that it is possible. The medium transfer device according to claim 1, wherein the contact portion overlaps the tip portion when the opening / closing member moves to the outside of the housing. The first medium transporting member is a heating unit having a heating source and a belt member that is heated by the heating source and moves in a predetermined direction, and the second medium transporting member has a pressure roller. The medium transfer device according to any one of claims 1 to 6, wherein the pressurizing portion forms the nip region . A developing device that attaches a developer to an electrostatic latent image,
A transfer unit that transfers the developer attached to the electrostatic latent image to a medium, and a transfer unit.
A fixing device for fixing the developer transferred to the medium to the medium,
An image forming apparatus comprising the medium transporting apparatus according to claim 7. An image forming apparatus having the medium transporting apparatus according to any one of claims 1 to 7.

Images