JP2004338905A - Paper feeder - Google Patents

Abstract

Provided is a good paper feeder which can prevent a lock of a pickup roller and double feed of paper, and can suppress an increase in the number of parts.
A sheet feeding device swings a pickup lever and presses a rolling contact surface of a pickup roller provided on a tip end side of the swing to a sheet housed and held on a back cover. Then, the pickup roller 53 is rotated to feed out the sheets one by one. An escape hole 15b is provided at a portion of the rear cover 15 facing the pickup roller 53 to avoid interference with the rolling contact surface 53b. A paper holding friction member 15c is provided on the paper guide surface 15a around the escape hole 15b. The low-friction rotating members 53a provided on both ends of the pickup roller 53 are brought into contact with the receiving portions 15g provided on the paper guide surface 15a around the escape hole 15b, so that the pickup roller 53 enters the escape hole 15b. To prevent contact between the rolling contact surface 53b and the paper guide surface 15a.
[Selection] Fig. 9

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a paper feeding device such as a printer.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, various paper feeders such as printers have been used.
For example, as shown in FIG. 10, a pickup roller 202 is rotatably provided on a swinging tip side of a pickup lever 201 whose base end is rotatably supported by a housing. In a state in which the rolling contact surface (rubber lining surface) of the sheet 202 is pressed against the uppermost sheet S stored and held on the sheet guide wall 203, the pickup roller 202 is rotated to feed the sheet. Have been.
[0003]
However, in this type of paper feeding device, as shown in FIG. 11, when the rolling contact surface of the pickup roller 202 comes into contact with the paper guide wall 203 when the paper S is lost, the paper feeding direction (the direction of arrow A) is changed. A large frictional force is generated between the rotating pickup roller 202 and the paper guide wall 203, and a force is generated in the pickup roller 202 to move in the direction opposite to the sheet feeding direction (the direction of arrow F). There is a problem that the pickup roller 202 is locked.
[0004]
Therefore, in order to avoid locking of the pickup roller 202, as shown in FIG. 12, a free rotation roller 205 biased by a spring 204 is disposed at a portion of the paper guide wall 203 facing the pickup roller 202, and the paper S A paper feeder has been proposed in which the rolling contact surface of the pick-up roller 202 is pressed against the peripheral surface of the free rotation roller 205 when there is no more, so that unnecessary frictional force is not generated (for example, Patent Document 1). 1).
[0005]
[Patent Document 1]
JP-A-8-259013
[0006]
[Problems to be solved by the invention]
However, when the free rotation roller 205 urged by the spring 204 is provided at the portion of the paper guide wall 203 facing the pickup roller 202, as shown in FIG. When feeding (2), the last sheet S (1) comes into contact with the free rotation roller 205 and is urged toward the pickup roller 202, so that it is difficult to hold the sheet S (1) on the sheet guide wall 203 side. In addition, a so-called "double feed" in which two sheets are fed together may occur.
[0007]
Further, since the free rotation roller 205 and the spring 204 are additionally provided on the paper guide wall 203 side, there is a problem that the number of parts increases.
[0008]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-described problems, and it is possible to prevent double-feeding at the time of feeding the second last sheet while avoiding locking of the pickup roller when there is no sheet. An object of the present invention is to provide a good sheet feeding device capable of suppressing an increase in points.
[0009]
[Means for Solving the Problems]
An object of the present invention is to provide a housing for accommodating and holding a plurality of sheets on a paper guide wall, a base end rotatably supported by the housing and a pickup roller rotatable to a swinging front end. And a pickup lever provided on the paper feeder that feeds the sheets one by one by rotating the pickup roller while pressing the rolling contact surface of the pickup roller against the sheet.
An escape hole for avoiding interference with the rolling contact surface is provided at a portion of the paper guide wall facing the pickup roller, and a relief hole is provided on the paper guide wall around the relief hole. A friction member for holding a sheet having a large frictional resistance and a smaller frictional resistance than the rolling contact surface;
By restricting the swinging position of the pickup roller between the pickup lever and the housing, contact with the paper guide wall when the rolling contact surface enters the relief hole is prevented. This is achieved by a sheet feeding device having a locking mechanism.
[0010]
According to the paper feeding device having the above-described configuration, a relief hole is provided at a position on the paper guide wall where the rolling contact surface of the pickup roller faces to avoid interference with the rolling contact surface. When the dynamic contact surface enters the relief hole, the locking mechanism prevents the contact with the paper guide wall.
[0011]
Therefore, even when the paper runs out of the paper guide wall, the rolling contact surface of the pickup roller enters the clearance hole and is prevented from contacting the paper guide wall, so that it does not directly hit the paper guide wall. Roller lock is prevented.
[0012]
Also, when the second sheet from the last is fed, the last sheet is held by the sheet holding friction member provided around the escape hole, so that double feeding becomes difficult.
[0013]
Furthermore, since a relief hole is formed in the paper guide wall and a friction member for holding the paper is provided around the clearance hole, an increase in the number of parts can be suppressed as compared with the case where a free-rotating roller or a spring is provided, thereby increasing costs. Can be suppressed.
[0014]
Preferably, the locking mechanism comprises a low-friction rotating member provided on the pickup roller so as to abut against the paper guide wall around the relief hole while rotating.
[0015]
According to the paper feeder having the above-described locking mechanism, the swinging position of the pickup roller is restricted when the paper is lost from the paper guide wall and the rolling contact surface of the pickup roller enters the clearance hole. This is performed by bringing the low friction rotating member provided on the pickup roller into contact with the paper guide wall around the relief hole while idling.
[0016]
Therefore, the swinging position of the pickup roller can be reliably regulated at the position closest to the rolling contact surface of the pickup roller whose contact with the paper guide wall is desired to be prevented. It is not necessary to set the accuracy to be high, and it is possible to suppress an increase in cost of the locking mechanism.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a sheet feeding device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
[0018]
FIG. 1 is an external perspective view showing a paper feeder of the present embodiment attached to a printer main body, FIG. 2 is a side sectional view showing a state where the paper feeder shown in FIG. 1 is mounted on the printer main body, and FIG. FIG. 2 is a perspective view of the sheet feeding device illustrated in FIG. 1 as viewed from a rear side.
[0019]
As shown in FIG. 1, an ASF (auto sheet feeder) configured to be detachably attached to the printer main body 1 via a hook 9 described later, as shown in FIG. (The mounting state is shown in FIG. 2). The paper feeding device 10 stores a plurality of sheets (cut sheets) of a predetermined size and feeds the sheets one by one to the main body 1 of the printer.
[0020]
The paper feeder 10 mainly includes a housing 13 including a lower case 11 and an upper cover 12. The lower case 11 is an integrally molded resin box member having a front cover 14, a rear cover 15 forming a paper guide wall, left and right side covers 16, 17 and a bottom cover 18. As shown in FIG. 2, the paper S is stored and held on the paper guide surface 15 a of the back cover 15 in an upright posture.
[0021]
On the upper surface side of the lower case 11, an upper opening 20 including a front cover 14, side covers 16, 17 and a rear cover 15 is provided. The upper cover 12 is inserted from the upper opening 20 and is fitted to the lower case 11 so as to cover a part of the upper opening 20. Here, the unblocked portion of the upper opening 20 is configured as a paper insertion opening into which a plurality of papers S can be inserted obliquely. The side covers 16, 17 are provided with hook portions 9, 9 for mounting the paper feeding device 10 to the printer main body 1. The hooks 9, 9 are, for example, inverted L-shaped members that protrude to the opposite side of the back cover 15 and protrude downward, and are configured to be hooked on the back of the printer body 1.
[0022]
At the upper end of the back cover 15, a flat paper guide 19 for supporting a portion of the paper located above the back cover 15 and a paper guide member 21 for guiding the paper S inserted from the upper opening 20 are provided. Have been.
[0023]
The paper guide member 21 is configured to be slidable along the upper end of the back cover 15, and the width between the paper guide member 21 and the side cover 17 is substantially the same as the paper width of the paper S to be inserted. With this setting, the sheet S can be inserted without being inclined in the width direction, guided by the side cover 17 and the sheet size defining member 21.
[0024]
As shown in FIG. 2, a friction pad 30 against which the lower end of the sheet S is pressed is provided on the lower inner side of the back cover 15 of the lower case 11. The friction pad 30 is provided rotatably so that the inclination angle with respect to the back cover 15 can be changed. The friction pad 30 will be described later in detail.
[0025]
On the bottom side of the lower case 11, a lower opening 22 constituted by a front cover 14, side covers 16, 17 and a bottom cover 18 is provided. The lower opening 22 forms a paper discharge port through which the paper S inserted from the upper opening 20 serving as a paper insertion port is discharged toward the paper transport path 5 of the printer main body 1. As shown in FIG. 3, the lower end of the back cover 15 is provided with a slit-shaped opening 23 for manually feeding the paper S or for releasing the rear end of the paper S out of the apparatus when the paper S is caught. Is provided.
[0026]
As shown in FIG. 2, a mounting rib 12 a formed integrally with the upper cover 12 is provided inside the upper cover 12 (on the rear cover 15 side). A pickup unit 50 for feeding a sheet is attached to the attachment rib 12a.
As shown in FIGS. 4 to 7, the pickup unit 50 feeds and moves the sheet S when pressed by the sheet S and a drive shaft 52 that is rotated by a motor 49 (only FIG. 8 is shown). The pickup roller 53 includes gears (rotation transmitting means) 54 to 59 that sequentially mesh with each other to transmit a rotational driving force between the drive shaft 52 and the pickup roller 53.
[0027]
The input stage gear 54 is integrated with the drive shaft 52, and the output stage gear 59 is integrated with the pickup roller 53.
[0028]
The pickup roller 53 is provided with a rolling contact surface 53b formed by winding a high friction material such as a rubber lining on the outer periphery of a core material such as plastic, and is provided at both ends in the axial direction of the pickup roller 53. A low friction rotating member 53a having a smaller diameter than the rolling contact surface 53b is provided.
[0029]
The low friction rotating member 53a in the present embodiment is formed by leaving the peripheral surface of the core material intact without winding the high friction material, and has a surface that is more slippery than the rolling contact surface 53b. ing. Therefore, the low friction rotating member 53a can abut on the back cover 15 around the escape hole 15b described later while rotating idly, and constitutes a locking mechanism described later.
[0030]
As shown in FIGS. 4 and 5, the pickup lever 51 is rotatably supported at its upper end side (base end side) by a mounting rib 12 a of an upper surface cover 12 constituting the housing 13. The pick-up lever 51 pivots toward the sheet bundle side, so that a pickup roller 53 rotatably provided at the lower end (oscillating tip side) of the pickup lever 51 is moved to the uppermost layer of the sheet bundle composed of a plurality of sheets S. The sheet S is pressed.
[0031]
By rotating the pickup roller 53 while the rolling contact surface 53b of the pickup roller 53 is pressed onto the sheet S, the sheets S can be sent out one by one.
[0032]
The drive shaft 52 is disposed on the pivot P1 of the pickup lever 51, as shown in FIGS. A clutch spring 60 as a torque transmission member is interposed between the drive shaft 52 and the pickup lever 51.
[0033]
The clutch spring 60 is a friction clutch that integrally rotates the drive shaft 52 and the pickup lever 51 by frictional engagement. The clutch spring 60 applies a force from the drive shaft 52 to the pickup lever 51 until a predetermined torque or more acts on the drive shaft 52. When the torque is transmitted and a predetermined torque or more acts on the drive shaft 52, the relative rotation of the drive shaft 52 with respect to the pickup lever 51 is allowed.
[0034]
As shown in FIG. 6, the clutch spring 60 includes a helical spring body 60 a frictionally engaged with the outer periphery of the drive shaft 52 and a hook receiving portion 51 p connected to the spring body 60 a and formed on the pickup lever 51. , 51p. In the clutch spring 60, an allowable transmission torque as a torque transmission member (friction clutch) is set by a friction locking force between the spring body 60a and the drive shaft 52.
[0035]
Thus, for example, when the pickup lever 51 is rotated in the sheet direction, the pickup lever 51 is moved to a position where the pickup roller 53 provided on the swinging tip side contacts the sheet S as shown in FIG. Moving. If the motor 49 is further driven while the pickup roller 53 is in contact with the sheet S, the maximum static friction torque (allowable transmission torque) between the drive shaft 52 and the clutch spring 60 due to the reaction that the pickup lever 51 receives from the sheet S. The drive torque described above acts, and the outer periphery of the drive shaft 52 and the clutch spring 60 rotate relative to each other. That is, the link between the drive shaft 52 and the clutch spring 60 is released, and the drive shaft 52 is moved relative to the pickup lever 51. Rotate. Thus, the rotation of the drive shaft 52 is transmitted to the pickup roller 53 via the gears (rotation transmitting means) 54 to 59, and the pickup roller 53 rotates.
[0036]
Here, the rotation direction of the drive shaft 52 when the pickup roller 53 feeds the sheet, and the rotation direction of the drive shaft 52 when the pickup lever 51 is rotated toward the sheet bundle via the clutch spring 60 that is a torque transmitting member. The number of intermediate gears 55 to 58 sandwiched between the input stage gear 54 and the output stage gear 59 is set to an even number in order to match.
[0037]
As shown in FIGS. 2 to 5, an escape hole for avoiding interference with the rolling contact surface (rubber lining surface) 53 b of the pickup roller 53 is provided in a portion of the back cover 15 facing the pickup roller 53. 15b are provided. When the paper S is completely lost on the paper guide surface 15a of the rear cover 15, when the rolling contact surface 53b of the pickup roller 53 directly contacts the paper guide surface 15a, the clearance hole 15b causes the rotating pickup roller 53 to rotate. It is provided to avoid locking due to a large frictional force.
[0038]
Therefore, the relief hole 15b is set slightly larger than the axial width of the rolling contact surface 53b. Further, in a state in which the rolling contact surface 53b of the pickup roller 53 has entered the escape hole 15b to some extent, as shown in FIG. 8A, the pickup lever 51 is moved so that the pickup roller 53 does not contact the rear cover 15. It is necessary to regulate the swing position.
[0039]
Therefore, between the pickup lever 51 and the housing 13, the swinging position of the pickup roller 53 is regulated, so that the back cover 15 when the rolling contact surface 53 b enters the relief hole 15 b is formed. Is provided with a locking mechanism for preventing the contact of the contact.
[0040]
As shown in FIGS. 8 and 9, the locking mechanism according to the present embodiment includes a low-friction rotating member 53 a provided at both ends in the axial direction of the pickup roller 53 and a paper guide surface 15 a around the relief hole 15 b. And a receiving portion 15g with which the low friction rotating member 53a contacts.
[0041]
The low-friction rotating member 53a is a portion where the core material is left without being covered with the rubber lining as described above. The low friction rotating member 53a has much smaller frictional resistance than the rolling contact surface 53b, and can smoothly run idle even when it comes into contact with the receiving portion 15g on the paper guide surface 15a, and generates a large frictional force. Not to be.
[0042]
In FIG. 8B, the cross-hatched portion indicates the opening surface of the pickup roller 53 and the clearance hole 15b when the rolling contact surface 53b of the pickup roller 53 enters the clearance hole 15b (the paper guide surface 15a). (Opening surface on the side).
[0043]
The relief hole 15b may be formed in a size that does not contact the rolling contact surface 53b of the pickup roller 53 in a state where the swinging position is regulated by the locking mechanism, and the depth and the cross-sectional shape are not limited. In order for the rear cover 15 to sufficiently fulfill the function of the paper guide, it is better to be as small as possible.
[0044]
Note that the locking mechanism according to the sheet feeding device 10 of the present invention is not limited to the configuration of the above-described embodiment, and the back surface at the stage when the rolling contact surface 53b of the pickup roller 53 enters the clearance hole 15b. It goes without saying that various configurations can be adopted as long as the configuration prevents contact with the cover 15.
[0045]
For example, a stopper that abuts against the back cover 15 may be provided at the tip of the swing of the pickup lever 51 to restrict the swing range of the pickup roller 53. Further, the swing range of the pickup roller 53 can be restricted by locking the base end side of the pickup lever 51 to a stopper protruding from the mounting rib 12a of the top cover 12.
[0046]
However, from the viewpoint of ensuring the accuracy of the position regulation of the pickup roller 53 with respect to the back cover 15, it is preferable to regulate the position at a position as close as possible to the pickup roller 53. That is, as in the locking mechanism according to the above-described embodiment, when the low friction rotating members 53a provided on both ends in the axial direction of the pickup roller 53 are brought into contact with the receiving portions 15g around the relief holes 15b. According to the embodiment, it is not necessary to set the component accuracy and the assembly accuracy of the pickup lever 51 rotated by the drive shaft 52 high, and it is possible to suppress an increase in cost of the locking mechanism.
[0047]
Further, as shown in FIGS. 8 and 9, on the paper guide surface 15a around the relief hole 15b, the frictional resistance is larger than that of the paper guide surface 15a, and the frictional resistance is larger than that of the rolling contact surface 53b. A paper holding friction member 15c such as a cork sheet having a small friction resistance is provided.
[0048]
Therefore, by providing the escape hole 15b at a portion of the rear cover 15 facing the pickup roller 53, the pressing force of the pickup roller 53 on the last sheet S when the second sheet S is fed decreases. Even if the frictional force between the sheet guide surface 15a and the last sheet S decreases, the last sheet S is held by the sheet holding friction member 15c, so that it is difficult to double feed.
[0049]
Here, the paper holding friction member 15c is formed in a U-shape excluding the side portion in the paper feeding direction among the four sides surrounding the escape hole 15b. This is because if the paper holding friction member 15c is provided in the side portion in the paper feeding direction (downward in FIG. 8B), when the last sheet S is sent out, the frictional resistance of the portion is disturbed. This is because there is a possibility that smooth paper feeding cannot be performed. The receiving portion 15g to which the low friction rotating member 53a of the pickup roller 53 contacts is secured inside the paper holding friction member 15c.
[0050]
As shown in FIG. 5, when the pickup unit 50 is rotated in the direction away from the sheet bundle S and held at the standby position, the rotation of the pickup roller 53 is set at a position where the peripheral surface of the pickup roller 53 presses. Accordingly, a cleaning member 40 made of a high friction material for cleaning the rolling contact surface 53b of the pickup roller 53 is provided.
[0051]
Next, the friction pad 30 will be described with reference to FIG.
[0052]
The friction pad 30 is rotatably provided so that the inclination angle with respect to the back cover 15 can be changed. In other words, the friction pad 30 is disposed below the rear cover 15 and separates each sheet S to be sent out by abutting the lower end of the sheet bundle housed and held in the rear cover 15, so that the rear cover 15 side Is rotatably supported by a shaft 31 provided at the front end, so that the extending portion 30a extending in the sheet feeding direction (diagonally lower left in the drawing) can be tilted up and down. The extension portion 30a is urged by a spring 32 so as to be lifted upward. A member having a high friction coefficient is attached to the upper surface of the friction pad 30 as necessary.
[0053]
Next, the operation of the sheet feeding device 10 of the above-described embodiment will be described.
[0054]
In the present embodiment, by rotating the drive shaft 52 by the motor 49, the pickup lever 51 can be rotated via the clutch spring 60, which is a torque transmitting member. At this time, the rotation direction of the drive shaft 52 when the pickup roller 53 feeds the paper is the same as the rotation direction of the drive shaft 52 when the pickup lever 51 is rotated toward the paper S via the clutch spring 60.
[0055]
Therefore, the pickup roller 53 can be pressed against the bundle of sheets S by rotating the drive shaft 52 in the sheet feeding direction. When the pickup roller 53 is pressed against the bundle of sheets S, the drive torque acting on the drive shaft 52 becomes equal to or greater than the set torque, and the drive shaft 52 rotates relative to the pickup lever 51. The pickup roller 53 is driven by the rotation of the drive shaft 52, and feeds out one pressed sheet S.
[0056]
In this case, the pressing force of the pickup roller 53 against the sheet S is determined in advance by the set torque of the clutch spring 60 as a torque transmitting member. Therefore, the pickup roller 53 can be pressed against the bundle of sheets S with a constant pressing force regardless of the thickness of the bundle of sheets S (the number of sheets).
[0057]
Further, when the pickup unit 50 is returned to the standby position after the sheet feeding, the drive shaft 52 is rotated in the opposite direction by reversing the motor 49. Then, the pickup lever 51 automatically rotates in a direction away from the bundle of sheets S, and the pickup roller 53 separates from the bundle of sheets S. Therefore, the sheet S can be easily taken out of the sheet feeding device 10 with the pickup roller 53 separated.
[0058]
Since the helical clutch spring 60 is used as the torque transmitting member, the driving force between the drive shaft 52 and the pickup lever 51 can be switched on and off with small and inexpensive components, and the component arrangement can be reduced. There are easy advantages. Here, the pressing force of the pickup roller 53 is determined by the friction locking torque of the clutch spring 60.
[0059]
When feeding the paper in this manner, the lower end of the paper S moves while sliding on the upper surface of the friction pad 30. At that time, in the paper feeding device 10, the friction pad 30 urged upward (toward the upper end of the paper) by the spring 32 is inclined downward according to the load at the time of feeding the paper.
[0060]
That is, when the pickup roller 53 sends out the sheet S, the sheet S pushes the surface of the friction pad 30, whereby the friction pad 30 is inclined.
[0061]
The inclination angle of the friction pad 30 at that time is changed by being pushed by the sheet S fed by the pickup roller 53. That is, the holding force for the paper S, which depends on the friction coefficient of the surface of the friction pad 30 and the strength (rigidity) of the paper S, becomes gradually smaller by inclining the extension 30a of the friction pad 30 downward to some extent. The sheet S is fed at the moment when the feeding force reaches an angle that exceeds the holding force.
[0062]
In addition, when a sheet of low rigidity (a sheet of weak stiffness: plain paper or the like) is sent out, the load at the time of sending out the sheet becomes small, so that the extending portion 30a of the friction pad 30 is inclined slightly. Accordingly, the angle of the friction pad 30 with respect to the sheet bundle becomes steep, and the friction angle with respect to the lower end of the sheet S to be sent becomes a suitable value, so that the sheet S can be separated and sent out smoothly.
[0063]
On the other hand, when a sheet of high rigidity (strong paper: postcard or the like) is sent out, the load at the time of sending out the sheet becomes large, so that the extending portion 30a of the friction pad 30 is greatly inclined downward. Therefore, the angle of the friction pad 30 with respect to the sheet bundle is reduced, and the friction angle with respect to the lower end of the sheet S to be sent out becomes a suitable value, so that the sheet S is separated and sent out smoothly.
[0064]
That is, the separation and supply of the paper S can be smoothly performed without being affected by the rigidity (strain) of the paper S. Therefore, according to the friction pad 30, the separation is performed at a friction angle suitable for the rigidity of the sheet S, so that the separation reliability of the sheet S is improved irrespective of the difference in the thickness of the sheet S, for example.
[0065]
When the paper feeding is completed, the pickup roller 53 is separated from the sheet bundle. A cleaning member 40 is provided at a standby position where the pickup roller 53 is separated from the sheet bundle. By rotating the drive shaft 52 in the direction opposite to the direction of paper feeding and rotating the pickup lever 51 to the standby position, the drive shaft 52 is continuously rotated for a few more seconds, so that the pickup roller The peripheral surface of 53 is rubbed.
[0066]
As a result, the dust adhered to the rolling contact surface 53b of the pickup roller 53 at the time of paper feeding and various components coating the paper are removed by the cleaning member 40, and the rolling of the pickup roller 53 is performed. The contact surface 53b can be automatically cleaned. Also in this case, the pressing force on the cleaning member 40 is determined by the set torque of the clutch spring 60.
[0067]
In this manner, the pickup roller 53 can be automatically cleaned simply by returning the pickup unit 50 to the standby position, so that the durability of the pickup roller 53 can be improved and the feeding failure can be prevented by maintaining a stable friction coefficient. I can do it.
[0068]
Further, if the paper S on the paper guide surface 15a runs out during the paper feeding, the rolling contact surface 53b of the pickup roller 53 may directly contact the paper guide surface 15a. In the device 10, a relief hole 15b is provided at a position on the rear cover 15 where the rolling contact surface 53b of the pickup roller 53 is opposed to avoid interference with the rolling contact surface 53b. When the contact surface 53b enters the escape hole 15b, the contact with the paper guide surface 15a is prevented by the above-described locking mechanism.
[0069]
Therefore, even when the sheet S runs out from the sheet guide surface 15a, the rolling contact surface 53b of the pickup roller 53 enters the clearance hole 15b and does not directly hit the sheet guide surface 15a. This state is maintained because the low-friction rotating members 53a adjacent to both sides of the pickup roller 53 abut on the receiving portion 15g on the paper guide surface 15a and are regulated in position. Moreover, in this state, the low-friction rotating member 53a only slips smoothly with respect to the receiving portion 15g and does not generate large friction, so that no extra load is applied to the pickup roller 53 or the pickup lever 51.
[0070]
Therefore, the rolling contact surface 53b of the pickup roller 53 can idle without contacting another member (the back cover 15), and almost no friction occurs between the pickup roller 53 and the paper guide surface 15a. Thus, the lock of the pickup roller 53 is prevented.
[0071]
Also, when the second sheet S from the last is fed, the last sheet S is stably held by the sheet holding friction member 15c provided around the escape hole 15b, so that the double feed is performed. It becomes difficult.
[0072]
Furthermore, since only the relief hole 15b is provided in the back cover 15 and the paper holding friction member 15c is provided around the relief hole 15b, the number of parts is increased as compared with the case where a free rotation roller or a spring is provided as in the conventional paper feeder. And cost increase can be suppressed.
[0073]
In addition, in the sheet feeding device 10 of the present embodiment, the position regulation of the pickup roller 53 when the rolling contact surface 53b of the pickup roller 53 enters the clearance hole 15b due to the loss of the sheet S is provided on the pickup roller 53 side. The low friction rotating member 53a makes contact with the receiving portion 15g provided around the escape hole 15b while idling.
[0074]
Therefore, the swinging position of the pickup roller 53 can be reliably restricted at the position closest to the rolling contact surface 53b of the pickup roller 53 whose contact with the back cover 15 is desired to be prevented. Can be set higher.
[0075]
Therefore, it is possible to prevent a situation in which the rolling contact surface 53b of the pickup roller 53 erroneously hits the paper guide surface 15a due to an assembly error or the like, and it is possible to improve reliability.
[0076]
Note that the configurations of the paper guide wall, the housing, the pickup roller, the pickup lever, the relief hole, the paper holding friction member, and the locking mechanism according to the paper feeding device of the present invention are limited to the configurations of the above embodiment. However, it goes without saying that various forms can be adopted based on the spirit of the present invention.
[0077]
【The invention's effect】
As described above, according to the paper feeding device of the present invention, a relief hole is provided at a position on the paper guide wall where the rolling contact surface of the pickup roller faces to avoid interference with the rolling contact surface. When the rolling contact surface enters the relief hole, the locking mechanism prevents the contact with the paper guide wall.
[0078]
Therefore, even when the paper runs out of the paper guide wall, the rolling contact surface of the pickup roller enters the clearance hole and is prevented from contacting the paper guide wall, so that it does not directly hit the paper guide wall. Roller lock is prevented.
[0079]
Also, when the second sheet from the last is fed, the last sheet is held by the sheet holding friction member provided around the escape hole, so that double feeding becomes difficult.
[0080]
Furthermore, since a relief hole is formed in the paper guide wall and a friction member for holding the paper is provided around the clearance hole, an increase in the number of parts can be suppressed as compared with the case where a free-rotating roller or a spring is provided, thereby increasing costs. Can be suppressed.
[Brief description of the drawings]
FIG. 1 is an external perspective view showing a sheet feeding device according to the present embodiment attached to a printer main body.
FIG. 2 is a side sectional view showing a state where the sheet feeding device shown in FIG. 1 is attached to a printer main body.
FIG. 3 is a perspective view of the sheet feeding device shown in FIG. 1 as viewed from the rear side.
FIG. 4 is a cross-sectional perspective view of a main part for describing the pickup unit shown in FIG. 2;
FIG. 5 is a side view for explaining the operation of a pickup lever in the pickup unit shown in FIG.
FIG. 6 is an overall perspective view of the pickup unit shown in FIG.
FIG. 7 is a front view of the pickup unit shown in FIG. 6;
FIGS. 8A and 8B are diagrams showing a relationship between a pickup roller and a paper guide surface of a back cover in the pickup unit shown in FIG. 5, wherein FIG. 8A is a side sectional view and FIG. 8B is a plan view of the paper guide surface. .
9 is an enlarged perspective view of a main part showing a relationship between a pickup roller and a paper guide surface of a back cover in the pickup unit shown in FIG. 5;
FIG. 10 is an explanatory diagram of a general paper feeding principle configuration.
11 is a diagram for explaining a problem when paper runs out in the principle configuration of FIG. 10;
FIG. 12 is a diagram illustrating a state when a sheet runs out in a conventional sheet feeding apparatus.
FIG. 13 is a diagram for explaining a problem in the sheet feeding device shown in FIG. 12;
[Explanation of symbols]
10 Paper feeder
13 Case
15 Back cover (paper guide wall)
15a Paper guide surface
15b relief hole
15c Paper holding friction member
15g receiving part (locking mechanism)
51 Pickup lever
53 Pickup roller
53a Low friction rotating member (locking mechanism)
53b rolling contact surface
S paper

Claims (2)

A housing for accommodating and holding a plurality of sheets on a paper guide wall, a pickup lever having a base end side rotatably supported by the housing and a pickup roller rotatably provided on a swinging tip side; In a paper feeder that feeds the sheets one by one by rotating the pickup roller while the rolling contact surface of the pickup roller is pressed against the sheet,
An escape hole for avoiding interference with the rolling contact surface is provided at a portion of the paper guide wall facing the pickup roller, and a relief hole is provided on the paper guide wall around the relief hole. A friction member for holding a sheet having a large frictional resistance and a smaller frictional resistance than the rolling contact surface;
By restricting the swinging position of the pickup roller between the pickup lever and the housing, contact with the paper guide wall when the rolling contact surface enters the relief hole is prevented. A sheet feeding device provided with a locking mechanism. 2. The paper feeder according to claim 1, wherein the locking mechanism comprises a low-friction rotating member provided on the pickup roller so as to abut on the paper guide wall around the escape hole while rotating. 3. apparatus.

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