Field of the Invention
The present invention relates to a sheet conveying apparatus conveying a sheet and an image forming apparatus including the same.
Description of the Related Art
Conventionally, an image forming apparatus, in which a sheet tray is detachably mounted on an apparatus body and a sheet that is stacked in the sheet tray is fed by a pickup roller, is disclosed in JP-A-2014-88227. A sheet tray and a sheet-feeding mechanism including the same configuration as the above-described image forming apparatus are illustrated in
A sheet-feeding mechanism 332 includes a separating roller 316, a pickup roller 308, and an abutting portion 350. The pickup roller 308 is swingably supported by a holder 347 about a roller shaft 343 of the separating roller 316. The abutting portion 350 is configured to interlock with the pickup roller 308 via a link 310.
A sheet tray 324 includes cams 324a, 324b, 324c, and 324d in a left end portion thereof. When the sheet tray 324 is mounted on an apparatus body, the abutting portion 350 engages with the cam 324d and the pickup roller 308 is positioned at a first position in which the pickup roller 308 abuts against a sheet that is stacked in the sheet tray 324. When the sheet tray 324 is removed from the apparatus body, the abutting portion 350 moves away from the cam 324a and the pickup roller 308 is positioned at a second position in which the pickup roller 308 moves upward away from the sheet that is stacked in the sheet tray 324 by an urging force of a spring 333.
By the way, in recent years, demand for a compact printer and a copier in the office or at home has been increasing. Thus it is desirable to downsize a sheet conveying apparatus, which is provided in the printer and the copier, in the height direction.
However, upon downsizing a product with that sheet-feeding mechanism 332, there is a concern that the holder 347 and the link 310 interfere with a conveyance guide provided above the pickup roller 308 in a case when the pickup roller 308 is moved from the first position to the second position. Thus, it has been difficult to achieve both downsizing of the product and ensuring a sufficient moving space for the pickup roller 308 to contact with and apart from the sheet.
According to one aspect of the invention, a sheet conveying apparatus includes a stacking unit, a feeding member, a conveyance guide, and a movement unit. The stacking unit is drawably mounted on an apparatus body and includes a stacking member on which a sheet is stacked. The feeding member feeds the sheet stacked on the stacking member. The conveyance guide is provided with an opening and disposed above the stacking unit. The conveyance guide configures a conveyance path through which the sheet is conveyed. The movement unit moves the feeding member between a first position on which the feeding member comes into contact with the sheet stacked on the stacking member and a second position disposed above the first position. The movement unit includes an entry portion configured to be located within the opening in a state where the feeding member is positioned at the second position.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments, features, and aspects of the invention and, together with the description, serve to explain the principles of the invention.
A first embodiment of this disclosure will be described. A printer 1, i.e., an image forming apparatus according to the first embodiment, is an electrophotographic laser beam printer. As illustrated in
The image forming portion 101 includes a cartridge 200 that is detachable with respect to an apparatus body 100A, a transfer roller 28, and a laser scanner unit 104. The cartridge 200 includes a photosensitive drum 27, a charger 29, and a developer 30. When an image formation command is output to the printer 1, an image forming process is started by the image forming portion 101 based on image information input from an external device such as a computer connected to the printer 1. The laser scanner unit 104 applies laser light L to the photosensitive drum 27 based on the input image information. Then an electrostatic latent image is formed by the applied laser light L on the photosensitive drum. 27, which has been charged in advance by the charger 29. Thereafter, the electrostatic latent image is developed by the developer 30 and a toner image is formed on the photosensitive drum 27.
A sheet S stacked in an intermediate plate 21 of the sheet conveying apparatus 106 is fed by a pickup roller 8, i.e., a feeding member, in parallel to the image forming operation described above. The sheets S are separated one by one by a feed roller 16 and a separating roller 9, and are conveyed to registration roller pair 26 and 42 by conveyance roller pair 23 and 25.
The registration roller pair 26 and 42 form a loop in the sheet S to correct skewing and conveys the sheet S to a transfer nip N formed between the photosensitive drum 27 and the transfer roller 28 at a predetermined conveying timing. A transfer bias is applied to the toner image on the photosensitive drum 27 from the transfer roller 28, and the toner image is transferred to the sheet S at the transfer nip N. The sheet S to which the toner image is transferred is conveyed to the fixing portion 103 and the toner image is fixed by a heating roller 32 and a pressing roller 31 of the fixing portion 103. Then, the sheet S is conveyed by conveyance roller pair 33 and 34, and discharging roller pair 35 and 36, and is discharged on a discharge tray 105.
Upon forming images on both sides of the sheet S, the discharging roller pair 35 and 36 are driven in a reverse rotation direction after the rear end of the sheet S with the image formed on its first surface (front surface) passes through a conveyance guide 43. Thus, the sheet S is guided to a duplex path 53 and is conveyed by first duplex conveyance roller pair 75 and 39. Furthermore, the sheet S is conveyed by second duplex conveyance roller pair 40 and 41, and is guided to the registration roller pair 26 and 42 by conveyance guides 51 and 52 configuring a part of the duplex path 53, i.e., a conveyance path. Similar to the first surface, another image is formed on the second surface of the sheet S at the transfer nip N, and the sheet then discharged on the discharge tray 105.
The multi-feeding portion 107 includes a multi-tray 61 that pivotably supports a multi-intermediate plate 62 on which the sheets are mounted, a multi-feeding roller 63, and a separating pad 64 disposed to face the multi-feeding roller 63. When a signal for feeding the sheet from the multi-feeding portion 107 is transmitted from a control unit 80 (see
Next, the sheet conveying apparatus 106 will be described. As illustrated in
The intermediate plate 21 is provided pivotable about a supporting point 21a and a lift plate 22 is provided below the intermediate plate 21. A gear (not illustrated) is provided in one end of the lift plate 22 and power is transmitted to the gear (not illustrated) from a transmission gear provided in the cassette 24. The transmission gear is driven by a feeding motor M described below and the intermediate plate 21 pivots in response to the upward and downward movement of the lift plate 22 so as to move upward and downward.
The separating roller 9, which is in pressure contact with the feed roller 16, forms a separation nip between the separating roller 9 and the feed roller 16 where the sheets are separated one by one. A torque limiter (not illustrated) is provided in the separating roller 9. The torque of the torque limiter is set such that the separating roller 9 is rotated together with the feed roller 16 when a single sheet is fed by the pickup roller 8. The torque is also set such that the separating roller 9 does not rotate when multiple sheets are fed by the pickup roller 8, so that the sheets are separated one by one in the separation nip.
Here,
As illustrated in
In addition, the movement unit 70 includes a detecting mechanism 71 and a cam mechanism 72. The detecting mechanism 71 includes a sheet position detecting lever 37 pivotably supported on the apparatus body 100A and the position detecting sensor 55. In the present embodiment, a photo interrupter is used as the position detecting sensor 55. An abutting portion 37b and a flag portion 37a are respectively formed on one and the other end of the sheet position detecting lever 37 across a pivotal shaft 37c. The abutting portion 37b is formed to abut against the sheet S stacked on the intermediate plate 21. The flag portion 37a is formed to be able to cover the position detecting sensor 55.
The sheet position detecting lever 37 is urged by a spring (not illustrated) in such a direction that the abutting portion 37b approaches the sheet S. In a state where the cassette 24 has been just mounted on the apparatus body 100A, the abutting portion 37b has been moved downward since the sheet position detecting lever 37 is urged by the spring (not illustrated). Thus, the position detecting sensor 55 covered by the flag portion 37a is in a non-detection state.
Then, if the position detecting sensor 55 is in the non-detection state, the control unit 80 drives the feeding motor M and moves the intermediate plate 21 upward via the lift plate 22. The abutting portion 37b is pressed upward by the sheet S mounted on the intermediate plate 21 moving upward, and the flag portion 37a moves downward. If the position detecting sensor 55 is intercepted by the flag portion 37a moving downward to go into a detection state (see
If the sheets S mounted on the intermediate plate 21 are sequentially fed, a height of an upper surface of the sheet S is decreased. Thus, the pickup roller 8 moves downward by an urging force of a tension spring 38 described below, and continuously abuts against the sheet S. On the other hand, the sheet position detecting lever 37 is rotated along with the height of the upper surface of the sheet S being decreased and if the abutting portion 37b moves downward by a predetermined amount, the position detecting sensor 55 is in the non-detection state in which the light is not intercepted by the flag portion 37a.
When the position detecting sensor 55 comes into the non-detection state, the control unit 80 drives the feeding motor M to move the intermediate plate 21 upward using the lift plate 22. Thus, the abutting portion 37b moves upward and the flag portion 37a moves simultaneously downward, while the position detecting sensor 55 covered by the flag portion 37a comes into the detection state. When the position detecting sensor 55 comes into the detection state, the control unit 80 stops driving of the feeding motor M. Controlling the feeding motor M to move the intermediate plate 21 upward and downward as described above, the apparatus is able to maintain the upper surface level of the sheet as long as a sheet S to be fed remains so that the pickup roller 8 reliably feed the sheet S.
The cam mechanism 72 includes a pressing lever 46, i.e., a swing member, and a releasing lever 50, i.e., a release member. The pressing lever 46 and the releasing lever 50 are respectively supported on a pivotal shaft 48 provided in the apparatus body 100A and are respectively rotatable with respect to the pivotal shaft 48. In addition, the cam mechanism 72 includes the tension spring 38, i.e., a second urging member, a compression spring 54, i.e., a first urging member, and a cam surface 74 formed on the upper surface of the cassette 24. It is noted that the resilient members, the tension spring 38 and the compression spring 54, may be replaced by, for example, magnets.
On one end of the pressing lever 46 is formed an entry portion 46a with an opening 46b, i.e., a cavity portion. The opening 46b is engaged with a protrusion portion 47a, i.e., an engagement portion, provided at the end portion of the roller holder 47. Here, the roller holder 47 and the entry portion 46a are connected so that a backlash to absorb posture change of the pressing lever 46 in swinging is formed between the protrusion portion 47a and the opening 46b. The tension spring 38 is stretched between the apparatus body 100A and an end portion opposite to the entry portion 46a of the pressing lever 46. The tension spring 38 urges the pressing lever 46 counterclockwise in
The releasing lever 50 includes a releasing portion 50a and a cam follower 50b, i.e., a movable portion, on the end portion opposite to the pivotal shaft 48. The compression spring 54 is stretched between the cam follower 50b and the apparatus body 100A. The compression spring 54 urges the releasing lever 50 clockwise in
The cam surface 74 formed on the upper surface of the cassette 24 includes a first horizontal surface 74a, a second horizontal surface 74c, and an inclined surface 74b. The second horizontal surface 74c, i.e., a contact portion, is formed above the first horizontal surface 74a. The inclined surface 74b connects the first horizontal surface 74a and the second horizontal surface 74c. The cam follower 50b of the releasing lever 50 moves upward and downward along the cam surface 74 under the urging force of the compression spring 54.
Next, the action of the pickup roller 8 in mounting operation and drawing operation of the cassette 24 will be described. When the cassette 24 is mounted on the apparatus body 100A, as illustrated in
When the cassette 24 is drawn from the apparatus body 100A, the cam follower 50b moves downward, under the urging force of the compression spring 54, by sequentially sliding on the second horizontal surface 74c, the inclined surface 74b, and the first horizontal surface 74a. The cam follower 50b moving downward, the releasing portion 50a of the releasing lever 50 comes to press the pressing lever 46 to rotate the pressing lever 46 clockwise as illustrated in
In other words, in drawing operation of the cassette 24 from the apparatus body 100A, the second horizontal surface 74c is separated from the cam follower 50b by the urging force of the compression spring 54 so that the pickup roller 8 moves from the first position to the second position.
Upon mounting the cassette 24 on the apparatus body 100A, the cam follower 50b moves upward sequentially sliding the first horizontal surface 74a, the inclined surface 74b, and the second horizontal surface 74c against the urging force of the compression spring 54. The cam follower 50b moving upward, the releasing portion 50a of the releasing lever 50 moves upward and the pressing lever 46 is rotated counterclockwise as illustrated in
In other words, in mounting operation of the cassette 24 on the apparatus body 100A, the second horizontal surface 74c presses the cam follower 50b against the urging force of the compression spring 54 so that the pickup roller 8 is moved from the second position to the first position by the tension spring 38.
Meanwhile, the conveyance guide 51 is provided above the cassette 24 mounted on the apparatus body 100A. As illustrated in
As illustrated in
It is noted that, when performing duplex printing in a state where the cassette 24 is mounted on the apparatus body 100A, the pickup roller 8 is positioned at the first position. In this case, as illustrated in
As described above, according to the embodiment, since the opening 51a is formed in the conveyance guide 51, the entry portion 46a and the conveyance guide 51 do not interfere with each other in a case when the cassette 24 is drawn and the pickup roller 8 is positioned at the second position,
The conveyance guide 51 and the entry portion 46a are thereby positioned close to each other in the height direction, enabling reduction (downsizing) of the height of the printer 1. In addition, while achieving downsizing of the printer 1, the pickup roller 8 is moved upward sufficiently away from the sheet S, preventing the sheet S from being damaged by the pickup roller 8 in a case when the cassette 24 is drawn.
It is noted that, in the present embodiment, the opening 51a is formed so that the entry portion 46a is positioned within. However, such an alternative configuration is considerable that an opening is formed larger than the opening 51a so as to be entered by the roller holder 47. With such a configuration, the degree of design flexibility of the conveyance guide 51 will be improved while achieving further downsizing of the apparatus.
It is noted that the present disclosure is not limited to the printer and can also be applied to another image forming apparatus such as a copier, a facsimile, and a multifunction printer.
Second Embodiment
Next, a second embodiment will be described. The second embodiment is provided by changing the configuration of the entry portion of the first embodiment. For the same configurations as those of the first embodiment, illustrations will be omitted and description will be provided by giving the same reference numerals.
A sheet conveying apparatus 206 according to the second embodiment includes the pressing lever 46. As illustrated in FIGS. 8 and 9, an entry portion 146a with an opening 146b is formed in an end of the pressing lever 46. A plurality of ribs 146c, i.e., guide ribs, are formed upward on the upper surface of the entry portion 146a and extend along the sheet conveyance direction.
As illustrated in
Here, in a state in which the cassette 24 is drawn from the apparatus body 100A and the pickup roller 8 is positioned at the second position, there is a case when the printer 1 performs duplex printing by feeding the sheet from the multi-feeding portion 107. In the first embodiment described above, however, there is a concern that the sheet S is caught by the entry portion 46a and a paper jam occurs, since the entry portion 46a protrudes within the opening 51a, as illustrated in
Thus, in the embodiment, the ribs 146c are provided on the upper surface of the entry portion 146a so as to guide the sheet S passing through the duplex path 53 in a state where the pickup roller 8 is positioned at the second position.
Thus, it is prevented that jamming due to interference in the sheet S and the entry portion 146a. Thus, even in a state where the cassette 24 is drawn from the apparatus body 100A and the pickup roller 8 is positioned at the second position, the printer 1 is able to perform duplex printing by feeding the sheet from the multi-feeding portion 107.
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.2015-043473, filed on Mar. 5, 2015, which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | Kind |
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2015-043473 | Mar 2015 | JP | national |
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6217018 | Tay | Apr 2001 | B1 |
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7918445 | Okamoto | Apr 2011 | B2 |
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Number | Date | Country |
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2009-107823 | May 2009 | JP |
2012-001316 | Jan 2012 | JP |
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2014-088227 | May 2014 | JP |
Number | Date | Country | |
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20160257508 A1 | Sep 2016 | US |