JP2005104605A - Paper feed device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To uniformly press-contact a pad relative to a paper feed roller even when molding accuracy and assembling accuracy of a member are not high in a paper feed device in which the paper feed roller and the pad are press-contacted and the paper is conveyed while clamping the paper therebetween. <P>SOLUTION: Spindle-like projections 31a, 31b are provided on a side surface of a pad holder 3 and are engaged with long shaft holes 42a, 42b formed on a housing 4 in a direction of the paper feed roller 1. Thereby, the pad holder 3 is mounted to the housing 4 in the state where it is urged to a paper feed roller direction by a spring 5 and it is movable in a radial direction of the paper feed roller and the pad 2 is uniformly press-contacted with the paper feed roller 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a paper feeding device, and more particularly, to a so-called friction pad type paper feeding device that prevents paper double feeding by pressing a paper feeding roller and a pad.

  An image forming apparatus with a low sheet feeding speed due to the simple structure and low cost of the sheet feeding apparatus that presses the sheet feeding roller and the pad and uses the frictional force of the pad to prevent double feeding of sheets. Has been widely used from now on. FIG. 6 shows an example of a conventional paper feeder using a pad.

The sheet feeding device of FIG. 6 includes a sheet feeding roller 1 and a pad holder 3 ′. A pair of shaft-like protrusions 30 are formed on the left end of the pad holder 3 ′ in a direction perpendicular to the paper surface. By inserting the shaft-like protrusions 30 into the shaft holes 40 formed in the housing 4 ′, The pad holder 3 ′ is attached to the housing 4 ′ so as to be rotatable about the shaft-like protrusion 30. A pad 2 made of urethane rubber or the like is attached to the surface of the pad holder 3 ', and the pad holder 3' is fed by a feed roller 5 by a pressing spring 5 interposed between the pad holder 3 'and the housing 4'. As a result of being urged in the direction, the pad 2 is in pressure contact with the paper feed roller 1. Then, the stacked sheet-like sheets are sandwiched between the sheet feed roller 1 and the pad 2 and sent out one by one from the right to the left in the figure (for example, Patent Document 1).
Japanese Patent Application Laid-Open No. 2002-308457 (2nd to 5th pages, FIGS. 2 to 8)

  By the way, in order to feed sheets one by one in a predetermined direction, it is necessary that the pad 2 is uniformly pressed against the sheet feeding roller 1. However, for example, as shown in FIG. 7, the case where the axial direction of the paper feed roller 1 and the upper surface of the pad 2 are not parallel may inevitably occur depending on the molding accuracy and assembly accuracy of the members. In such a case, the pressure contact force of the pad 2 differs in the axial direction, so that the paper is sent out obliquely, or if it is severe, a paper jam occurs.

  The present invention has been made in view of such conventional problems. The object of the present invention is to provide a uniform pad with respect to the paper feed roller even when the molding accuracy and assembly accuracy of the members are not high. An object of the present invention is to provide a sheet feeding device that is in pressure contact.

  Another object of the present invention is to prevent vibration noise generated between a sheet and a pad and / or between a sheet feed roller and a pad when feeding paper.

  In order to achieve the above object, in the paper feeding device according to the present invention, a paper feeding roller, a pad holding member having a pad on the surface and a shaft-like protrusion on the side surface, and a shaft formed long in the direction of the paper feeding roller. A housing having a hole, and a biasing means for biasing the pad holding member in the direction of the paper feed roller and pressing the pad against the paper feed roller are provided, and the shaft-like protrusion is engaged with the shaft hole. By doing so, the pad holding member is attached to the housing so as to be movable in the radial direction of the paper feed roller, so that the pad is uniformly pressed against the paper feed roller.

  Here, a buffer member may be interposed between the pad holding member and the housing in order to suppress vibration noise during paper feeding. At this time, it is preferable that a protrusion is provided at the center of the surface of the pad holding member opposite to the surface on which the pad is attached in the sheet feeding roller axial direction, and a buffer member is interposed between the protrusion and the housing. As the buffer member, a member having a flexible sheet attached to the surface of the foam is preferable.

  Further, in order to suppress vibration noise at the time of paper feeding, a weight may be attached to the surface of the pad holding member opposite to the surface to which the pad is attached.

  In the paper feeding device according to the present invention, since the shaft hole for attaching the pad holding member to the housing is made longer in the direction of the paper feeding roller, the pad holding member can be moved in the radial direction of the paper feeding roller, thereby forming the member. Regardless of the accuracy and assembly accuracy, the pad always comes into press contact with the paper feed roller uniformly. This effectively prevents the paper from being obliquely fed and jammed.

  In addition, if a buffer member is interposed between the pad holding member and the housing, the vibration of the pad during sheet feeding is absorbed by the buffer member, so that the generation of vibration noise can be suppressed. Furthermore, if a protrusion is provided in the center of the surface of the pad holding member opposite to the surface where the pad is attached in the feed roller axial direction, and a buffer member is interposed between the protrusion and the housing, vibration noise can be generated. Generation | occurrence | production can be suppressed and the movement (oscillation) of a pad holding member can be performed smoothly. When the cushioning member having a flexible sheet attached to the surface of the foam is used, the pad holding member can be moved more smoothly.

  Also, if a weight is attached to the surface of the pad holding member opposite to the surface on which the pad is attached, the pad holding member is heavier and the natural frequency is changed, and the vibration noise during feeding due to resonance is generated. It can be suppressed.

  Hereinafter, a sheet feeding device according to the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below.

  FIG. 1 is an assembly diagram showing an embodiment of a sheet feeding device of the present invention. The sheet is conveyed from left to right as indicated by the arrows in the figure. A pad 2 is attached to the upper surface of a substantially rectangular parallelepiped pad holder (pad holding member) 3. Then, shaft-like protrusions 31a and 31b (shown in FIG. 3) are formed on both side surfaces of the pad holder 3 when viewed from the sheet conveying direction, and a protrusion 32 whose tip is rounded is formed at the center of the lower end surface of the rear side surface. Has been. On the other hand, the housing 4 is formed with a recess 41 for accommodating the pad holder. Long side shaft holes 42b and 42a (shown in FIG. 3) that are engaged with the shaft-like protrusions 31b and 31a are formed on the side wall of the recess 41 in the drawing. A cylindrical portion 43 for fixing the spring (biasing means) 5 is formed at the bottom center of the recess 41. A buffer member 6 is attached to the inclined surface of the concave portion 41 on the downstream side of the cylindrical portion 43 in the sheet conveying direction.

  Assembling of the paper feeding device having such a configuration is performed as follows. First, the spring 5 is attached to the back surface of the pad holder 3. Specifically, the upper end of the spring 5 is inserted and fixed in a circumferential groove 33 (shown in FIG. 2) formed on the back surface of the pad holder 3. Next, after the lower end of the spring 5 is inserted into the cylindrical portion 43 of the housing 4, the pad holder 3 is pushed into the concave portion 41 of the housing 4 against the repulsive force of the spring 5. Then, the shaft-like protrusions 31a and 31b formed on both side surfaces of the pad holder 3 are respectively inserted into the shaft holes 42a and 42b of the housing, and the pad holder 3 is inserted into the recess 41 of the housing 4 with respect to the sheet conveying direction. Install in a state of being biased in a substantially vertical direction. A cross-sectional view at this time is shown in FIG.

  As can be understood from FIG. 2, the pad holder 3 is biased upward by the spring 5, and the shaft-like protrusions 31 a and 31 b of the pad holder 3 abut on the inner upper surfaces of the shaft holes 42 a and 42 b of the housing 4. It is held in the recess 41 of the housing 4. At this time, the protrusion 32 formed on the rear side surface of the pad holder 3 is in a state of being in slight contact with the buffer member 6 attached to the housing 4. When the paper feed roller 1 is pressed against the pad holder 3, the pad holder 3 is pushed downward by the paper feed roller 1, and the axial protrusions 31a, 31b of the pad holder 3 are formed in the shaft holes 42a, 42b. It is released from the contact with the inner upper surface, and stops at a predetermined position in the shaft holes 42a and 42b where the pressing force of the paper feed roller 1 and the repulsive force of the spring 5 are balanced.

  In this way, the pad holder 3 can be moved in the radial direction of the paper feed roller 1 (downward in the figure) by the pressing force received from the paper feed roller 1, so that, for example, as shown in FIG. When the axial direction is inclined from the horizontal direction, the pad holder 3 moves downward by a different amount in the left-right direction in the figure in response to the different pressing force received from the paper feed roller 1 in the axial direction. As a result, even if the paper feed roller 1 is tilted, the pad 2 comes into uniform pressure contact with the paper feed roller 1.

  1 and 2, the pad holder 3 and the housing 4 are not in direct contact with each other, and a spring 5 and a buffer member 6 are interposed therebetween. For this reason, most of the vibration generated between the paper P and the pad 2 during paper feeding is absorbed by the spring 5 and the buffer member 6 and is not transmitted to the housing 4. As a result, the vibration noise is significantly suppressed as compared with the prior art. Although the mounting position of the buffer member 6 is not particularly limited, in the paper feeding device of FIGS. 1 and 2, the buffer member 6 is provided at a position facing the protrusion 32 formed on the pad holder 3 and is in contact with the protrusion 32. . Thereby, it becomes easy to press the pad 2 uniformly against the paper feed roller 1, and at the same time, vibration noise can be suppressed. The operation mechanism will be described with reference to FIG.

  FIG. 4 is a view of the pad holder 3 attached to the housing 4 as viewed from the downstream side in the paper transport direction. A protrusion 32 is formed at the center of the lower end surface of the rear side surface of the pad holder 3, the tip of which is rounded, and is in contact with the buffer member 6 attached to the housing 4. As shown in FIG. 3, when the axial direction of the paper feed roller 1 is tilted from the horizontal direction, the pad holder 3 tilts accordingly. At this time, the protrusion 32 is below the rear side of the pad holder 3. By being formed at the center of the end face, the pad holder 3 swings with the protrusion 32 as a fulcrum. Thereby, the swing of the pad holder 3 is smooth and reliable. Since the buffer member 6 is interposed between the protrusion 32 and the housing 4, the vibration of the pad holder 3 is absorbed by the buffer member 6 as described above, and the vibration noise is suppressed.

  The buffer member used in the present invention is not particularly limited as long as it can absorb vibrations, and examples thereof include elastic members such as rubber and foam. Among these, in order to smoothly swing the pad holder, it is preferable to attach a flexible sheet to the surface of the foam.

  It is also effective to change the weight of the pad holder in order to prevent vibration noise during feeding. In other words, the natural frequency is changed by changing the weight of the pad holder, and the vibration noise at the time of paper feeding due to resonance is suppressed. FIG. 5 shows a state diagram in which the weight 7 is attached to the pad holder 3. In FIG. 5, a weight 7 having a substantially U shape in plan view is fixed to the back surface of the pad holder 3 so as to surround a circumferential groove 33 for positioning the spring 5 (shown in FIG. 2). The weight of the weight 7 may be appropriately determined so that resonance does not occur in consideration of the weight and shape of the pad holder 3. Further, the fixing place of the weight 7 is not limited to the back surface of the pad holder, and may be the side surface or the top surface, but the back surface of the pad holder is desirable in consideration of downsizing of the apparatus. Although one weight is attached in FIG. 5, it is of course possible to disperse and attach a plurality of weights.

  The pad used in the present invention is preferably made of a material having a predetermined frictional force, such as urethane rubber, silicone rubber, natural rubber, chloroprene, ethylene / propylene rubber, and the form thereof may be solid. It may be a foam.

It is an assembly view showing an embodiment of a paper feeding device of the present invention. It is a sectional side view which shows one Embodiment of the paper feeder of this invention. It is explanatory drawing which shows the press-contact state of a paper feed roller and a pad. It is a figure explaining rocking | fluctuation of the pad holder which uses a protrusion as a fulcrum. It is an assembly drawing of the pad holder provided with the weight. It is a schematic explanatory drawing which shows the conventional paper feeder. It is explanatory drawing which shows the press-contact state of the paper feed roller and pad in the conventional paper feeder.

Explanation of symbols

1 Feed roller 2 Pad 3 Pad holder (pad holding member)
4 Housing 5 Spring (biasing means)
6 Buffer member 7 Weight 31a, 31b Shaft-shaped protrusion 32 Projection 41 Recessed part 42a, 42b Shaft hole P Paper

Claims (5)

A feed roller;
A pad holding member having a pad on the surface and an axial protrusion on the side surface;
A housing having a shaft hole formed long in the direction of the paper feed roller;
Urging means for urging the pad holding member in the direction of the paper feed roller and pressing the pad against the paper feed roller;
By engaging the shaft-like protrusion with the shaft hole, the pad holding member is attached to the housing so as to be movable in the radial direction of the paper feed roller, so that the pad is uniformly pressed against the paper feed roller. A paper feeding device characterized by that.   The sheet feeding device according to claim 1, wherein a buffer member is interposed between the pad holding member and the housing.   3. A protrusion is provided at a central portion of the surface of the pad holding member opposite to the surface on which the pad is attached in the sheet feeding roller axial direction, and a buffer member is interposed between the protrusion and the housing. Paper feeder.   The sheet feeding device according to claim 2 or 3, wherein the cushioning member has a flexible sheet attached to the surface of the foam.   The sheet feeding device according to any one of claims 1 to 4, wherein a weight is attached to a surface opposite to a surface to which the pad of the pad holding member is attached.

Images