Patent Application
20180057288
This application is based on and claims the benefit of priority from Japanese Patent application No. 2016-165727 filed on Aug. 26, 2016, the entire contents of which are incorporated herein by reference.
The present disclosure relates to an image forming apparatus including a sheet conveying device configured to convey a sheet.
An image forming apparatus, such as a copying machine and a printer, is provided with a sheet conveying device which conveys a sheet along a sheet conveying path to an image forming part. The sheet conveying device includes a pickup roller and a feed roller. The pickup roller is configured to feed the sheet. The feed roller is configured to separate the fed sheet one by one and then to convey the separated sheet. On the conveying path, a registration roller configured to correct a skew of the sheet fed by the feed roller is provided downstream from the sheet conveying device in the conveying direction.
In addition, depending on a layout of the conveying path, an intermediate roller may be provided between the feed roller and the registration roller in order to assist the sheet for conveying. The conventional intermediate roller includes a rubber made roller and a resin made pulley both of which are pressed each other. In order to obtain a sufficient sheet conveying ability, a nip formed between the roller and the pulley is required to be wide.
By the way, when the resin made pulley may be formed by using a die, the pulley is made to have a difference in outer diameter in its axil direction owing to a draft. The difference in the outer diameter causes a difference in a sheet conveying rate in the axial direction, and thus the sheet may be skewed. The wider the nip between the roller and the pulley is, the greater the degree of the skew is. When one of the intermediate roller is provided between the feed roller and the registration roller, if the degree of the skew is great, the skew may not be corrected by the registration roller. When two to more intermediate rollers are provided, the sheet may be deflected between the intermediate rollers and easily wrinkled.
In accordance with an aspect of the present disclosure, A sheet conveying device includes a sheet stacking part, a conveying path and a conveying roller. On the sheet stacking part, a sheet is placed. Along the conveying path, the sheet is conveyed. The conveying roller is provided on the conveying path and configured to convey the sheet in a conveying direction along the sheet conveying path. The conveying roller includes a drive roller and a driven roller which is pressed against the drive roller and is driven by the drive roller to be rotated. The drive roller has a rotating drive shaft and a drive roller body rotatable together with the rotating drive shaft. The driven roller has a rotating shaft and a driven roller body supported by the rotating shaft in a rotatable manner. The driven roller body has a plurality of roller parts which are arranged in an axial direction of the rotating shaft and pressed against the drive roller body.
In accordance with an aspect of the present disclosure, an image forming apparatus includes the above described sheet conveying device and an image forming part configured to form an image on the sheet conveyed by the sheet conveying device.
The above and other objects, features, and advantages of the present disclosure will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present disclosure is shown by way of illustrative example.
Hereinafter, with reference to figures, an image forming apparatus and a sheet conveying device according to an embodiment of the present disclosure will be described.
First, with reference to
An apparatus main body 2 of the printer 1 includes a sheet conveying device 3 configured to feed a sheet S, an image forming part 6 configured to form a toner image on the fed sheet S, a fixing device 7 configured to fix the toner image to the sheet S, a sheet ejection device 8 configured to eject the sheet S on which the toner image is fixed and an ejection tray 9 on which the ejected sheet S is received.
In the apparatus main body 2, a conveying path 10 along which the sheet S is conveyed is formed so as to extend from the sheet conveying device 4 to the sheet ejection device 8 through the image forming part 6 and the fixing device 7. The conveying path 10 has a curved path 10a curved upward at about 180° from the sheet conveying device 4 toward image forming part 6. The conveying path 10 extends substantially horizontally from the curved path 10a to the fixing device 7 through the image forming part 6 and then is curved upward from the fixing device 7 toward the sheet ejection device 8.
Next, with reference to
The sheet stacking part 21 is formed into a tray like shape having a size of the sheet S to be placed. On the sheet stacking part 21, a pair of side cursors 31 is supported in a slidable manner in a width direction perpendicular to the conveying direction so as to adjust the sheet S in the width direction. In addition, on the sheet stacking part 21, an end cursor 32 is supported in a slidable manner in the conveying direction so as to adjust a rear edge of the sheet S. Furthermore, on the sheet stacking part 21, a placement plate 33 on which the sheet S is placed is supported in a turnable manner around its upstream side end in the conveying direction. A downstream side end portion of the placement plate 33 in the conveying direction is biased upward by a biasing member (not shown) so that the sheet S placed on the placement plate 33 is kept in an inclined posture in which the downstream side end portion of the sheet S is inclined upward. On a center portion in the width direction of the downstream side end portion of the placement plate 33, a friction pad 34 is attached.
The pickup roller 22 has a rotating shaft 22a and a roller body 22b rotatable together with the rotating shaft 22a.
The pickup roller 22 is supported above the center portion of the downstream side end portion of the placement plate 33 in a rotatable manner. When the placement plate 33 on which the sheet S is placed is inclined into the above described inclined posture, the sheet S is held between the friction pad 34 and the roller body 22b and then fed to the downstream side by rotation of the rotating shaft 22a.
The feed roller 23 has a rotating drive shaft 23a and a feed roller body 23b rotatable together with the rotating drive shaft 23a. The feed roller 23 is supported downstream from the pickup roller 22 in the conveying direction at a center portion in the width direction. The rotating drive shaft 23a is driven by a driving source (not shown) such as a motor to be rotated. The rotating drive shaft 23a is coupled to the rotating shaft 22a of the pickup roller 22 via an idle gear or a timing belt. Thus, when the feed roller 23 is rotated in the conveying direction (the counterclockwise direction in
Against the feed roller 23, a separation roller 35 (refer to
The separation roller 35 stops the rotation until torque of a predetermined value is applied, while being driven by the feed roller 23 to be rotated when torque of the predetermined value or more is applied. When one sheet is fed by the pickup roller 22, because the torque applied to the separation roller 35 is larger than the predetermined value, the separation roller 35 is driven by the feed roller 23 to be rotated and then to convey the sheet S. On the other hand, when a plurality of the sheet S are fed by the pickup roller 22, because the torque applied to the separation roller 35 is smaller than or equal to the predetermined value, the separation roller 35 stops the rotation with the sheet S held between the separation roller 35 andthe feed roller 23 so that the uppermost sheet S is separated from the other lower sheets S and then conveyed to the downstream side by the feed roller 23.
Next, with reference to
The intermediate roller 24 includes a drive roller 41 disposed on an inner circumference side of the conveying path 10 and a driven roller 42 disposed on an outer circumference side of the conveying path 10, also as shown in
As shown in
As shown in
With reference to
The two roller parts 53 are made by resin molding using a die. Owing to a draft of the resin molding, each roller part 53 is formed into a truncated cone shape which has a larger diameter end 53b at one end in the axial direction and a smaller diameter end 53a at the other end. That is, an outer circumference face of each roller part 53 is inclined so as to be tapered from the larger diameter end 53b toward the smaller diameter end 53a. The two roller parts 53 are arranged such that inclined directions of the outer circumference faces are oppose to each other, as shown in
As shown in
The registration roller 5 has a drive roller 61 and a driven roller 62 which is pressed against the drive roller 1, as shown in
A sheet conveying operation of the sheet conveying device 4 having the above described configuration will be described. The sheet S placed on the placement plate 33 of the sheet stacking part 21 shown in
The two roller parts 53 of the driven roller 42 of the intermediate roller 24 are arranged such that the inclined directions of the outer circumference faces of the two roller parts 53 are different from each other, as shown in
Additionally, because the drive roller body 41b of the drive roller 41 has a width wider than that of the feed roller body 23b of the feed roller 23, sheet powder generatedby friction between the feed roller 23 and the sheet S is hardly passed so that image density unevenness caused by the sheet powder can be prevented. In addition, because the width W between the both outer ends of the two roller parts 53 is wider than the width of the drive roller body 41b of the drive roller 41, an effect of steps produced on the end portion of the roller part 53 at the resin molding is hardly exerted on the sheet S so that occurrence of a folding line on the sheet S can be prevented.
When the sheet S conveyed by the intermediate roller 24 is conveyed to the registration roller 5, the drive roller 61 of the registration roller 5 stops the rotation. Thereby, a tip edge of the conveyed sheet S abuts against the nip between the drive roller 61 and the driven roller 62. However, because the drive roller 41 of the intermediate roller 24 is rotating, the sheet S is being conveyed by the intermediate roller 24. As a result, the sheet S is deflected until an entire of the tip edge of the sheet S abuts against the nip so that the skew of the sheet S can be corrected. Then, when the drive roller 61 of the registration roller 5 is started the rotation at a suitable timing, the sheet S is conveyed from the nip toward the image forming part 6.
As described above, according to the sheet conveying device 4 of the present disclosure, because the driven roller body 52 of the driven roller 42 of the intermediate roller 24 is formed by the two roller parts 53 each which is independently rotatable, the appearance of the skew of each roller part 53 is distributed so that the skew of the sheet S is hardly occurred. Thereby, the skew can be accurately correctedby the registration roller 5. Accordingly, it becomes possible to convey the sheet S straightly by using a simple configuration.
Additionally, the two roller parts 53 are arranged such that the smaller diameter ends 53a face outward and the larger diameter ends 53b face inward, and the entire of the two roller parts 53 is formed such that the center portion has a large diameter and the both end portions have a smaller diameter. This makes a conveying rate of the center portion of the sheet S faster. Accordingly, because the sheet S is conveyed such that the center portion of the sheet S is pulled forward, wrinkle is hardly generated on the sheet S.
Furthermore, the driven roller 42 has the two roller parts 53. This makes the width of each roller part 53 to be narrow. Thereby, the difference in the outer diameter owing the draft becomes small so that the degree of the skew can be reduced.
The two roller parts 53 may be arranged such that the smaller diameter ends 53a face inward and the larger diameter ends 53b face outward, as shown in
In the present embodiment, because one of the intermediate roller 24 is arranged between the feed roller 23 and the registration roller 5, the deflection of the sheet S and wrinkling of the sheet S can be reduced. However, depending on layout and length of the conveying path 10 between the feed roller 23 and the registration roller 5, a plurality of the intermediate roller 24 may be arranged.
The pickup roller 22, the feed roller 23, the separation roller 35, the intermediate roller 24 and the registration roller 5 are disposed at the center portion in the width direction so that the sheet S can be conveyed stably regardless of its size.
While the preferable embodiment and its modified example of the sheet conveying device and the image forming apparatus of the present disclosure have been described above and various technically preferable configurations have been illustrated, a technical range of the disclosure is not to be restrictedby the description and illustration of the embodiment. Further, the components in the embodiment of the disclosure may be suitably replaced with other components, or variously combined with the other components. The claims are not restrictedby the description of the embodiment of the disclosure as mentioned above.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-165727 | Aug 2016 | JP | national |
