Patent Grant
11634290
The present invention relates to a sheet conveyance apparatus which conveys a sheet, and an image forming apparatus including this sheet conveyance apparatus.
Hitherto, an image forming apparatus including a detection portion which detects a grammage and surface properties of a sheet by irradiating the sheet being conveyed in a conveyance path with an ultrasonic wave and light is suggested (refer to Japanese Patent Laid-Open No. 2016-55933). This image forming apparatus includes a pair of guides forming the conveyance path, and a pressing roller pressing the sheet onto a first guide of the pair of guides. This pressing roller stabilizes a posture of the sheet conveyed in the conveyance path, and improves detection accuracy of the grammage and surface properties of the sheet by use of the ultrasonic wave and the light.
However, the pressing roller disclosed in Japanese Patent Laid-Open No. 2016-55933 is urged by a pressing spring, and a reaction force of the pressing spring is received, for example, by a second guide of the pair of guides. It occurred that the second guide sustained creep deformation when the reaction force of the pressing spring had acted on the second guide for an extended period of time. Then, in a case where the second guide has been deformed, it occurs that the detection accuracy is deteriorated due to changes in a distance between detection elements of the detection portion, and a detection position of the sheet.
According to a first aspect of the present invention, a sheet conveyance apparatus includes a first guide configured to guide a sheet, a second guide disposed to face the first guide, and configured to form a conveyance path together with the first guide, a conveyance portion configured to convey a sheet in the conveyance path, a pressing portion configured to press the sheet being conveyed in the conveyance path against the first guide, an urging portion configured to urge the pressing portion in an urging direction toward the first guide, a receiving member configured to hold the pressing portion and receive a reaction force of the urging portion, and a detection unit including a first detection portion disposed on the first guide, and a second detection portion facing the first detection portion and disposed on the second guide, the detection unit being configured to change an output value based on presence and absence of the sheet at a detection position in the conveyance path, wherein the second guide provided with the second detection portion, and the receiving member are movably disposed with respect to the first guide provided with the first detection portion respectively, and are configured to be positioned with respect to the first guide independently from each other.
According to a second aspect of the present invention, a sheet conveyance apparatus includes a first guide configured to guide a sheet, a second guide disposed to face the first guide, and configured to form a conveyance path together with the first guide, a conveyance portion configured to convey a sheet in the conveyance path, a pressing portion configured to press the sheet being conveyed in the conveyance path against the first guide, an urging portion configured to urge the pressing portion in an urging direction toward the first guide, a receiving member configured to hold the pressing portion and receive a reaction force of the urging portion, and a detection unit including a detection portion disposed on the second guide, the detection unit being configured to change an output value based on presence and absence of the sheet at a detection position in the conveyance path, wherein the second guide provided with the detection portion, and the receiving member are movably disposed with respect to the first guide respectively, and are configured to be positioned with respect to the first guide independently from each other.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
General Configuration
First, a first embodiment of the present disclosure will be described. A printer 1, which is an image forming apparatus, is a laser beam printer of an electrophotographic system forming a monochrome toner image. To be noted, in the following descriptions, a sheet means the sheet on which an image is formed by the printer 1, and includes, for example, such as a paper and an overhead transparency (OHP).
The printer 1, as shown in
When an image formation job is output to the printer 1, an image formation process is started by the image forming portion 30 based on image-information which is input by an outside computer coupled to the printer 1 and the like. The image forming portion 30 includes a laser scanner 52, a process cartridge P including a photosensitive drum 51, and a transfer roller 531. In adjacent to the photosensitive drum 51, a charge roller, a development roller, and the like, not shown, are disposed. The photosensitive drum 51 and the transfer roller 531 form a transfer nip T1.
The laser scanner 52 irradiates the photosensitive drum 51 with a laser beam based on the input image-information. At this time, the photosensitive drum 51 has been charged by the charge roller in advance, and an electrostatic latent image is formed on the photosensitive drum 51 by being irradiated with the laser beam. Thereafter, this electrostatic latent image is developed by the development roller, and the monochrome toner image is formed on the photosensitive drum 51.
In parallel with the image formation process described above, the sheet S is fed from the feed unit 2. The feed unit 2 includes a cassette 3, which is detachable from and attachable to an apparatus body 1A of the printer 1, a feed roller 21, and a separation roller pair 22. The sheet S stored in the cassette 3 is fed by the feed roller 21, and the sheet S fed by the feed roller 21 is separated into one sheet at a time by the separation roller pair 22.
To be noted, it is acceptable to provide an intermediate board capable of supporting the sheet and capable of ascending and descending to the cassette 3 and, for example, is acceptable to lift the intermediate board by inputting the image formation job, and bring the sheet, supported on the intermediate board, and the feed roller 21 into contact with each other. Further, it is acceptable that one of a pair of rollers of the separation roller pair 22 is a pad or the like, and it is possible to apply a torque limiter method or a retard roller method to the separation roller pair 22.
The toner image on the photosensitive drum 51 is transferred to the sheet S, sent out by the feed unit 2 and conveyed by the conveyance roller pair 41, at the transfer nip T1 by electrostatic load bias applied by the transfer roller 531. Residual toner remained on the photosensitive drum 51 is recovered by a cleaning blade, not shown. The sheet S on which the toner image has been transferred is provided with a predetermined heat and pressure by a fixing film 61 and a press roller 62 of the fixing unit 6, and the toner is melted and adhered (fixed). Inside the fixing film 61, a heating element such as a ceramic heater is disposed. The sheet S passed through the fixing unit 6 is discharged to the discharge tray 8 by the discharge roller pair 7.
In a case where the images are formed on both surfaces of the sheet S, the sheet S with the image formed on a first surface is conveyed to a duplex conveyance path CP in a switchback manner by an inversion roller pair 65. The duplex conveyance path CP guides the sheet S to the conveyance roller pair 41. Then, the sheet S is conveyed to the transfer nip T1 again by the conveyance roller pair 41, and the image is formed on a second surface at the transfer nip T1, and the sheet S is discharged to the discharge tray 8.
Sheet Conveyance Apparatus
Next, the sheet conveyance apparatus 4 will be described in detail. As shown in
The conveyance frame 42, the conveyance inlet guide 43, and a conveyance guide 451 of the conveyance guide unit 45 form a conveyance path 10, and the conveyance roller pair 41, serving as a conveyance portion, conveys the sheet S in the conveyance path 10.
The conveyance inlet guide 43 rotatably supports a drive roller 411 of the conveyance roller pair 41. The conveyance frame 42 supports a holder 413 rotatably supporting a driven roller 412 of the conveyance roller pair 41, and an optical sensor 46. The driven roller 412 is urged toward the drive roller 411 by a spring 414 disposed between the holder 413 and the conveyance frame 42, and is rotatably driven by the drive roller 411. The optical sensor 46, serving as a first detection portion, includes a light-irradiating portion 46a, which irradiates light, and a light-receiving portion 46b, which receives the light emitted from the light-irradiating portion 46a. To be noted, a transfer frame 532 of a transfer portion 53, described later, also constitutes a part of the sheet conveyance apparatus 4. The transfer frame 532 is pivotably supported by the side plate 44 around a transfer frame shaft 532a.
Transfer Portion
Next, the transfer portion 53 will be described in detail. The transfer portion 53, as shown in
The reason why the transfer frame 532 is provided in the manner of pivotable around the transfer frame shaft 532a as the center is, when a jam occurs in the conveyance path 10, to secure a space to deal with a jamming sheet.
As shown in
Conveyance Guide Unit
Next, the conveyance guide unit 45 will be described in detail. The conveyance guide unit 45 includes, as shown in
A groove portion 11 is formed on an upper side of the conveyance guide 451. The holding member 454 includes a protruded portion 454a which protrudes upward, and the protruded portion 454a engages with the groove portion 11 of the conveyance guide 451 in a width direction W (refer to
That is, in a state where the holding member 454 is positioned at the closed position, the protruded portion 454a does not engage with the conveyance guide 451 in the urging direction UD, and is separated from the conveyance guide 451. Therefore, although unitized, these conveyance guide 451 and holding member 454 are capable of pivoting independently from each other.
The conveyance guide 451 includes abutment portions 451a, 451a which abut on the conveyance frame 42, and the abutment portions 451a, 451a, serving as a second abutment part, are disposed outside an area R1 of width of the conveyance path 10 in the width direction W. As described above, the conveyance guide 451 is positioned with respect to the conveyance frame 42 in a state where the abutment portions 451a, 451a are pressed against the conveyance frame 42 by an urging force of the guide spring 453, and where by the transfer frame 532 receives a reaction force of the guide spring 453.
The transfer frame 532 receives the reaction force of the guide spring 453 at the one-end 453a. The one-end 453a is disposed adjacent to the transfer frame shaft 532a, which is a pivot shaft of the transfer frame 532, in the width direction W. Therefore, the reaction force received by the transfer frame 532 from the one-end 453a hardly deforms the transfer frame 532 in the urging direction UD.
Further, the conveyance guide 451, as shown in
As shown in
The conveyance guide unit 45 includes a holding member spring 456, serving as an urging portion and a first urging portion to urge the pressing roller 455 toward the conveyance frame 42 (refer to
Although the rotation shaft 455a of the pressing roller 455 is movable inside the long hole 12, since the rotation shaft 455a is urged in the urging direction UD by the holding member spring 456, the pressing roller 455 is always pressed against the conveyance frame 42.
Although, by receiving a reaction force of the holding member spring 456, the holding member 454 attempts to displace in a direction opposite of the urging direction UD, an abutment portion 454b of the holding member 454 abuts on the transfer frame 532. That is, the transfer frame 532, serving as a positioning member and a frame, positions the holding member 454 by abutting on the abutment portion 454b of the holding member 454 and thus receiving the reaction force of the holding member spring 456.
To be noted, as shown in
In this way, the holding member 454 is positioned with respect to the conveyance frame 42 in a state where the pressing roller 455 is pressed against the conveyance frame 42 by the urging force of the holding member spring 456, and the transfer frame 532 receives the reaction force of the holding member spring 456.
Sheet Detection Process
Next, a detection process of the detection unit 15 will be described. As shown in
When the sheet S reaches a detection position in the conveyance path 10, the light irradiated from the light-irradiating portion 46a is blocked by the sheet S before reaching the reflecting plate 452, and the light-receiving portion 46b does not receive the light. Since in this way a state of the light-receiving portion 46b of the detection unit 15 is switched from a light-receiving state to a light-blocked state, an output value of the light-receiving portion 46b is changed, and presence of the sheet S at the detection position is detected.
In this detection process, the sheet S is pressed against the conveyance frame 42 by the pressing roller 455, and is conveyed along the conveyance frame 42. This is because, if a position in a thickness direction of the sheet S is changed inside the conveyance path 10, timing of the sheet S to block the light changes, and timing of the detection unit 15 to detect the presence of the sheet S varies. In this embodiment, since the sheet S is detected at the detection position with the sheet being pressed against the conveyance frame 42 by the pressing roller 455, it is possible to improve detection accuracy. When a trailing edge of the sheet S has passed through the detection position, the light-receiving portion 46b becomes the light-receiving state again. Thus, the detection unit 15 changes the output value based on the presence and absence of the sheet S at the detection position.
Effect of Reaction Force of Holding Member Spring on Detection Unit
Next, an effect of the reaction force of the holding member spring 456 on the detection unit 15 will be described with reference to
It occurs that the transfer frame 532 sustains a creep deformation by continuing to receive this reaction force. Then, the holding member 454 positioned by the transfer frame 532 is also displaced. For example, in a case where the conveyance guide 451 has been also displaced by displacement of the holding member 454, a position of the reflecting plate 452 varies, and there is a possibility that the light-receiving portion 46b is not able to receive a reflected light from the reflecting plate 452. Then, the detection unit 15 detects erroneously, and becomes not able to correctly detect a defective conveyance such as an occurrence of the jam.
However, in this embodiment, a large gap is provided in the urging direction UD between the protruded portion 454a of the holding member 454 and the groove portion 11 of the conveyance guide 451. In other words, inside the area R1, the holding member 454 does not engage with the conveyance guide 451 in the urging direction UD.
Therefore, in a case where the transfer frame 532 is displaced by the effect of the reaction force of the guide spring 453, the holding member 454 also varies the position along with the displacement of the transfer frame 532. On the other hand, the conveyance guide 451 does not vary a position since the gap between the protruded portion 454a and the groove portion 11 absorbs a variation of the position of the holding member 454. Herewith, the position of the reflecting plate 452 supported by the conveyance guide 451 also does not vary.
As described above, in this embodiment, the conveyance guide 451 and the holding member 454 are movably disposed with respect to the conveyance frame 42, and are positioned independently from each other with respect to the conveyance frame 42. Herewith, even if the holding member 454 varies the position in the urging direction UD by the effect of the reaction force of the guide spring 453, the position of conveyance guide 451 supporting the reflecting plate 452 is not affected. Therefore, the distance between the optical sensor 46 and the reflecting plate 452 is kept constant, and it is possible to improve the accuracy to detect the sheet S.
Further, even if the transfer frame 532 is displaced in the center area in the width direction W by being pressed by the abutment portion 454b of the holding member 454, the displacement of the transfer frame 532 is small in adjacent to the transfer frame shaft 532a of the transfer frame 532. Then, since the conveyance guide 451 is abutting on a position adjacent to the transfer frame shaft 532a of the transfer frame 532 via the one-end 453a of the guide spring 453, the conveyance guide 451 is hardly affected by the displacement of the transfer frame 532. That is, the conveyance guide 451 is not affected by the displacement of the holding member 454. Therefore, it is possible to improve the accuracy to detect the sheet S.
Further, since the sheet S is always pressed by the pressing roller 455, a posture of the sheet S passing through the conveyance path 10 is stabilized, and it is possible to improve the accuracy to detect the sheet S.
Next, although a second embodiment of the present disclosure will be described, only the configuration of the detection unit 15 of the first embodiment is changed in the second embodiment. Therefore, illustrations of similar configurations to the first embodiment will be omitted herein, or descriptions will be provided by putting the same reference characters on drawings.
A sheet conveyance apparatus 9 according to the second embodiment includes, as shown in
The conveyance guide unit 95 includes, as shown in
The ultrasonic wave receiving element 96 and the ultrasonic wave transmitting element 952 constitute a detection unit 215, and the detection unit 215 is disposed across the conveyance frame 92 and the conveyance guide 951. The ultrasonic wave receiving element 96 and the ultrasonic wave transmitting element 952 are disposed in the center area of the conveyance path 10 in the width direction W. Further, a distance and positional relationship between the ultrasonic wave receiving element 96 and the ultrasonic wave transmitting element 952 are secured by abutting the conveyance guide 951 on the conveyance frame 92 and thus positioning the conveyance guide 951.
Sheet Detection Process
Next, a detection process of the detection unit 215 will be described. As shown in
In this detection process, the sheet S is pressed against the conveyance frame 92 by the pressing roller 455, and conveyed along the conveyance frame 92. Herewith, a variation in the degree of the attenuation due to a passing position of the sheet S is reduced, and it is possible to improve the detection accuracy. In a case of the detection unit 215 configured like this embodiment, levels of transmission and reception of the ultrasonic wave transmitting element 952 and the ultrasonic wave receiving element 96 are adjusted after assembled to the sheet conveyance apparatus 9. Receiving sensitivity after the adjustment is affected by a change in the distance between the ultrasonic wave transmitting element 952 and the ultrasonic wave receiving element 96, it is necessary to keep this distance constant.
As described above, in this embodiment, an ultrasonic wave sensor is applied to the detection unit 215. Also, in this case, if the position of the holding member 454 is varied in the urging direction UD by the effect of the reaction force of the guide spring 453, a position of the conveyance guide 951 supporting the ultrasonic wave transmitting element 952 is not affected. Therefore, the distance between the ultrasonic wave transmitting element 952 and the ultrasonic wave receiving element 96 is kept constant, and it is possible to improve the accuracy to detect the sheet S. Further, since the sheet S is always pressed by the pressing roller 455, the posture of the sheet S passing through the conveyance path 10 is stabilized, and it is possible to improve the accuracy to detect the sheet S.
To be noted, although the optical sensor 46, serving as the first detection portion, which includes the light-irradiating portion 46a and the light-receiving portion 46b, is disposed on the conveyance frame 42 and the reflecting plate 452, serving as the second detection portion, is disposed on the conveyance guide 451, it is not limited to this. For example, it is acceptable to dispose the reflecting plate 452 on the conveyance frame 42 and dispose the optical sensor 46 on the conveyance guide 451. In any case where the optical sensor 46 and the reflecting plate 452 are respectively disposed across the conveyance frame 42 and the conveyance guide 451, it is acceptable that the optical sensor 46 is disposed on either one of the conveyance frame 42 and the conveyance guide 451 and the reflecting plate 452 is disposed on the other.
Further, although, in the second embodiment, the ultrasonic wave receiving element 96 is disposed on the conveyance frame 92 and the ultrasonic wave transmitting element 952 is disposed on the conveyance guide 951, it is not limited to this. For example, it is acceptable to dispose the ultrasonic wave transmitting element 952 on the conveyance frame 92 and dispose the ultrasonic wave receiving element 96 on the conveyance guide 951. Further, it is acceptable to dispose the light-receiving portion or the light-irradiating portion in place of the ultrasonic wave receiving element 96 and dispose the light-irradiating portion or the light-receiving portion in place of the ultrasonic wave transmitting element 952.
Further, although, in any of the embodiments described above, the detection unit 15, 215 is disposed across the conveyance frame and the conveyance guide, it is not limited to this. For example, as shown in
The optical sensor 346 includes a light-irradiating portion 346a and a light-receiving portion 346b, and light irradiated from the light-irradiating portion 346a is reflected by the sheet S being conveyed in the conveyance path 10, and is received by the light-receiving portion 346b. The optical sensor 346 changes an output value based on a light-receiving or light-blocked state. As described above, even if the detection elements of the detection unit are disposed only on the conveyance guide 451, since the conveyance guide 451 is not affected by a positional variation (displacement) of the holding member 454, it is possible to improve the accuracy to detect the sheet S.
Further, as shown in
Further, although, in any of the embodiments described above, the sheet S is pressed against the conveyance frame by the pressing roller 455, it is not limited to this. For example, it is acceptable to provide a low sliding resistance rib shape to the holding member 454 in place of the pressing roller 455. Further, it is not limited to a roller, and acceptable to apply other rotary members, such as a belt.
Further, although, in any of the embodiments described above, the holding member 454 is positioned by receiving the reaction force of the holding member spring 456 by the transfer frame 532, it is not limited to this. For example, it is acceptable to position the holding member 454 by receiving the reaction force of the holding member spring 456 by the side plate 44 or other frames of the apparatus body 1A.
Further, although, in any of the embodiments described above, the conveyance guide 451, 951 and the holding member 454 are configured to pivot, it is not limited to this. For example, it is acceptable to configure the conveyance guide 451, 951 and the holding member 454 to move in linear motion.
Further, although, in any of the embodiments described above, the pressing roller 455 is directly pressed against the conveyance frame 42, 92, it is not limited to this. For example, it is acceptable to dispose a locking member at a position where the pressing roller 455 and the conveyance frame come into contact with each other. The locking member is configured not to engage with the conveyance frame in the urging direction UD, and is pressed by the pressing roller. Herewith, even in a case where it is not possible to secure rigidity of the conveyance frame adequately, it is possible to reduce a displacement of the conveyance frame due to being pressed by the pressing roller 455, and possible to improve the detection accuracy.
Further, although, in any of the embodiments described above, descriptions are provided using the printer 1 of the electrophotographic system, the present disclosure is not limited to this. For example, it is possible to apply the present disclosure to an image forming apparatus of an ink jet system which forms the image on the sheet by ejecting a liquid ink through a nozzle.
Embodiment(s) of the present invention can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2019-235145, filed Dec. 25, 2019, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2019-235145 | Dec 2019 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 8340563 | Nakajima et al. | Dec 2012 | B2 |
| 10254698 | Matsumoto | Apr 2019 | B2 |
| 20160139550 | Ishida | May 2016 | A1 |
| 20190063901 | Mitsui | Feb 2019 | A1 |
| 20210061597 | Matsumoto | Mar 2021 | A1 |
| Number | Date | Country |
|---|---|---|
| 2010-260662 | Nov 2010 | JP |
| 2016-003066 | Jan 2016 | JP |
| 2016-055933 | Apr 2016 | JP |
| 2019-104635 | Jun 2019 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20210198070 A1 | Jul 2021 | US |
