JP2719590B2 - Paper feeder - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device that separates a document sheet or the like one by one and feeds it to an image forming apparatus such as an electronic copying apparatus or a printing apparatus. .

[Prior Art] A stacker for stacking and storing sheets, a feeding unit for feeding a sheet in contact with the uppermost or lowermost sheet of the sheets stored in the stacker, and a feeding unit provided downstream of the feeding unit in the sheet feeding direction. A sheet rotating unit that rotates in the sheet feeding direction, a pad unit that presses against the sheet rotating unit to prevent double feeding of sheets, and a separating unit that includes an urging unit that presses the sheet rotating unit. An image forming apparatus such as an electronic copying apparatus, which includes a timing feeding unit that receives a sheet from the separating unit and feeds the sheet at a timing.
Alternatively, in a sheet feeding device that feeds a document or other sheets one by one to a printing device or the like of a printing machine or the like, the pad body 101 has a flat shape as shown in FIG. There is one that is curved along the paper feed rotating body 102.

[Problems to be Solved by the Invention] However, among the above, the flat pad body of FIG.
In the one having 101, if the urging means 103 is strengthened in order to prevent double feeding of sheets, the pad body 101 generates minute vibration, and unpleasant chatter noise is generated. If the urging means 103 is weakened, there is a problem that the adjustment of the urging means 103 requires a lot of time and effort, such as double feeding of sheets.

On the other hand, in the configuration as shown in FIG. 12, although the separation performance was somewhat improved, the contact area between the pad body 101 and the paper feed rotating body 102 was increased, and the driving power was increased. There is also a problem that the curved edge portion of the pad body wears quickly.

[Object of the Invention] The present invention has been made in view of such problems in the related art, and does not require man-hours to adjust the pressing force of the pad body against the paper feed rotating body, and does not generate any unpleasant noise. It is another object of the present invention to provide a sheet feeder having an improved separating means with a small driving power.

[Means for Solving the Problems] The gist of the present invention for achieving the above object is to provide a stacker for stacking and storing sheets, and a stacker for contacting the uppermost or lowermost sheet of the sheets stored in the stacker. Feeding means for feeding a sheet, and a sheet feeding rotator provided downstream of the feeding means in the sheet feeding direction and rotating in the sheet feeding direction; A separating means comprising a pad body for blocking and a biasing means for pressing the pad body in the direction of the paper feed rotating body; and a timing feeding means for receiving a sheet from the separating means and feeding it in a timely manner. In the paper feeding device, the pad body is supported so that the front end portion swings with respect to the surface of the paper feed rotating body, and the pad body is located at the front end side of the contact point between the paper feeding rotary body and the pad body. A sheet feeding device characterized in that a leading end portion of the sheet member protrudes toward the sheet feeding rotating body from a straight line connecting the contact point and the nip point of the sheet of the timing feeding means.

Further, according to a further aspect of the present invention, a curved surface having a radius of curvature larger than the radius of curvature of the paper feed rotating body is provided at least on the leading end side in the paper feeding direction of the paper feed rotating body facing surface of the pad body. The paper feed device is characterized by being provided.

[Operation] The sheet inserted and placed in the stacker is sent out by the operation of the feeding means, and the lowest or highest sheet and a plurality of sheets following the lowest or highest sheet enter the separation means. .

On the downstream side of the separating means, add the sheet for a predetermined time,
A timing feeding means for feeding a sheet to the apparatus body such as a copying apparatus is provided, and the timing feeding means strongly pulls the sheet in the feeding direction. On the other hand, the rear end of the sheet is still held by the separating means, and the sheet is bent at the protruding portion of the pad body and acts in a direction to separate the pad body from the paper feed rotating body. However, since the leading end of the pad body is supported by the apparatus frame with a play, the pad body operates so that the leading end can be lifted, and the contact force with the paper feed rotating body is rather increased. Therefore, the first paper in contact with the paper feed rotating body is fed in the feeding direction as it is, but the feeding of the second and subsequent papers is prevented, and the separating operation is reliably performed.

Further, since the radius of curvature of the curved portion of the pad body is made larger than the radius of curvature of the paper feed rotating body, the contact point between them is small, and the sliding resistance force due to sliding contact with the paper feed rotating body is small,
The driving power may be small.

Further, since the contact point of the pad body with the paper feed rotating body is not at the edge portion, wear is small.

Further, since it is not necessary to use a strong urging means, chatter vibration and the like do not occur, which contributes to the improvement of the durability of the pad body.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In this embodiment, as shown in FIG. 4, a description will be given of a sheet feeding device 20 for supplying a copy original one by one in the electronic copying apparatus 1.

As shown in FIG. 4, the electronic copying apparatus 1 is provided with a platen 3 on which an original is placed on an upper surface of an apparatus body 2, a sheet feeding cassette 4 for supplying a copy sheet on one side, and another side. Is provided with a paper discharge tray 5 for receiving a copied copy sheet.

On the other hand, an electrostatic latent image is formed inside the apparatus main body 2 through an optical system including an exposure lamp 6 and a mirror group 7 which reciprocate while irradiating the original from the lower surface of the platen 3 and a zoom lens block 8. A photosensitive drum 9, a developing device 10 for attaching toner to the electrostatic latent image to develop the toner image, a transfer device 11 for transferring the toner image to a copy sheet, a fixing device 12 for fixing the transferred toner image, and the like are housed therein. I have.

As shown in FIG. 3, the sheet feeding device 20 includes a sheet stacker 22 for placing an original sheet on the main body frame 21, a sheet feeding unit 30 for feeding sheets one by one, and an original sheet for the original body 2. It is transported and placed on the platen 3, and after the copying process is completed, the paper is discharged further backward and discharged to a paper discharge stacker 23.

As shown in FIG. 1, the sheet feeding section 30 has a sheet guide plate 31 extending in the sheet feeding direction following the leading end of the sheet stacker 22, and a sheet stacker 22 below the sheet guide plate 31. , A kick roller 32 is provided as a feeding means partially cut out in a half-moon shape. Above the kick roller 32, an upper guide plate 33 is provided with an angle of attack at the front end so as to receive the sheet. A part of the upper guide plate 33 is notched, and a weight 35 is provided, which rotates through the notched portion to the center of the shaft 34 and presses the upper surface of the sheet. The weight 35 has an arm 35a having elasticity and a shaft 3
It is urged clockwise in Fig. 1 around 4
When the solenoid 36 is ON, it is pulled down in the counterclockwise direction in FIG.

On the other hand, from below the sheet guide plate 31, there is provided a gate stopper 37 for aligning and stopping the leading edge of the sheet when the sheet is inserted into the sheet stacker 22, and the gate stopper 37 stops when the sheet is not energized. When the solenoid 38 is energized, it rotates counterclockwise in FIG. 1 and is pulled down to the lower surface of the sheet guide plate 31.

A separating roller 41, which is a sheet-feeding rotary member constituting the separating means 40, is provided alongside the kick roller 32, and a part of the outer peripheral cylindrical surface is exposed on the upper surface of the sheet guide plate 31 as shown in the figure. ing.

As shown in FIG. 2 showing the main part near the separating roller 41 in more detail, a main body frame is provided above the separating roller 41.
A rigid separating plate 42, which is a first separating means, which hangs down from the immovable portion 21 and has an acute angle of attack upon receiving the leading edge of the sheet, is provided.

The rigid separating plate 42 is formed of a hard plate that is not deformed by the sheet feeding force. A first passage gap a for the sheet is provided between the lower end edge of the rigid separating plate 42 and the separating roller 41.

Further, on the back surface of the rigid separating plate 42, an elastic separating plate 43, which is a second separating means made of an elastic material which is deformed by the sheet feeding force, is adhered. A second passage gap b for the sheet is provided between them. The first passage gap a and the second passage gap b have a relationship of a = b or a> b.

The angle of attack α between the two separating plates 42 and 43 with respect to the upper surface of the sheet is approximately optimal according to elaborate experimental results, a = 50 ° to 57 °. Of course, it is not limited to this numerical value. Absent.

Next, on the downstream side in the sheet feeding direction of the both separating plates 42 and 43,
A pad block 45, which is a pad body of another member constituting the separating means 40, is disposed near the separating plates 42 and 43.

As shown in FIG. 2, the pad block 45 includes a pad 46 that comes into contact with the separating roller 41 to separate sheets one by one, and a pad holder 47 that holds the pad 46.

As shown in FIG. 2, the pad 46 is in contact with the cylindrical outer peripheral surface of the separating roller 41, and an angle formed between a line connecting the contact point P and the center of the separating roller 41 and a line perpendicular to the sheet surface. It has been experimentally obtained that γ is optimal in the range of 9 ° to 16 °, but it is needless to say that the value is not limited to this value.

And, from the contact point P on the lower surface of the pad 46 to the sheet feeding direction, as shown in the drawing, it has an arc shape having a radius of curvature larger than the radius of curvature of the separating roller 41. A protrusion 46a is formed. The P
The side that receives the sheet from the point has a flat portion, and therefore the angle of attack is also the angle γ. The pad 46 is made of a rubber-like soft material, for example, urethane rubber having a hardness of 80 degrees.
It is stiffer and has a lower coefficient of friction, but has a higher coefficient of friction than the coefficient of friction between sheets.

On the other hand, as shown in FIG. 2, the pad holder 47 holding the pad 46 has the rear end engaging portion 51 supported by the support plate 48 of the main body frame 21 and is pressed in the direction of the separating roller 41 by the biasing spring 50. Have been.

That is, the pad block 45 is supported as a whole by the three points of the point P, the force Q of the biasing spring 50, and the engaging portion 51.

The urging direction K of the urging spring 50 is such that the pad holder 47 is moved in the second direction with respect to the contact point P between the separating roller 41 and the pad 46.
In the figure, it is arranged so as to urge clockwise.
Then, as shown in FIG.
51 has a slight play 51a.

Further, the pad holder 47 has a stopper portion 52 for holding the pad holder 47 on the opposite side of the engaging portion 51, and there is no backlash between the holders so as not to restrain the pad holder at a normal assembly setting position. It is provided. Further, if the pad holder 47 is formed separately from the support portion for supporting the pad 46 and the holding portion for holding the support portion, a state in which the pad holder 47 is pressed against the separating roller is maintained. Further, the engagement portion 51 is provided further downstream of the application point Q than in the sheet feeding direction, and is located at a distance s separated from the point P.

Further, as can be seen in the figure, an angle of attack β is provided on the side of the pad 46 that receives the sheet.

The angle of attack β is optimally between 15 ° and 22 °, but is not limited to this value.

 As described above, the angles of attack α, β, and γ satisfy the relationship α> β> γ.

On the downstream side of the separation means 40, a registration space, which is a timing feeding means including a pair of rollers for delivering a sheet to the conveyance unit 24, is separated by a registration space 60 provided by largely bending the sheet guide plate 31. Rollers 61 and 62 are provided. A sheet guide 63 that guides the sheet to the transport unit 24 is provided on the exit side of the registration rollers 61 and 62.

Then, the contact point between the two registration rollers 61 and 62, that is, the nip point R for holding the sheet is, as shown in FIGS. 8 and 9, the pad 46 having a radius of curvature larger than the radius of curvature of the separating roller 41. It is located above the tangential direction A at the curved tip.

In addition, along the sheet guide plate 31, the gate stopper 37
On the upstream side of the registration roller 6, an empty sensor 65 for detecting the presence or absence of a sheet in the sheet stacker 22 is provided.
A registration sensor 66 for detecting arrival of a sheet is provided in front of 1 and 62.

Next, the operation will be described. In describing the operation, in addition to FIGS. 1 to 4 showing the configuration, FIG. 5 to FIG.
The figures are referred to.

The sheet is placed on the sheet stacker 22. At this time, the solenoid 38 is not energized yet and the gate stopper
37 is flipped upward and holds the leading edge of the sheet. Further, the solenoid 36 is also in the OFF state, and the weight 35 is at a position away from the sheet.

Then, when the copying apparatus 1 is started by pressing a paper feed start button (not shown), as shown in the timing chart of FIG. 10, the solenoid 36 is turned on after a very short time, and the weight 35 comes into contact with the sheet. And press it down. Then, the slight kick roller 32 and the separating roller 41 start rotating at the same time. However, the solenoid 38 is turned ON for the first time after a minute time element, and the gate stopper 37 prevents the sheet from advancing to align the paper edge between the time elements. In the above operation, when the sheet is not supplied to the sheet stacker 22, an alarm is issued by the detection of the empty sensor 65, and the apparatus 1 does not start.

Then, the stacked sheets advance forward as a result of the rotation of the kick roller 32, and come into contact with the rigid separating plate 42 having an acute angle of attack α as shown in FIG. Then, a plurality of lower sheets pass through the first passage gap a. Further, as shown in FIG. 6, these sheets are pressed against an elastic separating plate 43 as a second separating means, and pass through a second passage gap b smaller than the first passage gap a to minimize the number of sheets. The sheet passes.

The sheet then enters the separating means 40, where the angle of attack β of the leading edge of the pad 46 is smaller than the angle of attack α of the rigid separating plate 42, so that the separating action is performed here as well. You. Then, the sheet enters separation means 40 composed of separating roller 41 and pad block 45.

Since the coefficient of friction of the pad 46 is larger than that of the sheets and smaller than that of the surface of the separating roller 41,
If two sheets have entered so far,
The upper sheet stops on the pad 46 side, and the sheet on the separating roller 41 side is sent as it is.

Further, when only one sheet is sent, the sheet is sent out with the arrow facing down since the lower surface of the sheet receives a stronger frictional force. Since the angle of attack γ between the lower surface of the pad 46 and the sheet before the pad 46 contacts the separating roller 41 is further reduced, the separating action is further ensured. The sheet loosening action associated with the decrease in the angle of attack is more clearly shown with reference to FIG.

The sheet separated by the separating means 40 advances along the curved lower surface of the pad 46, and the front end of the sheet temporarily descends to the resist space 60 formed by the sheet guide plate 31 bent greatly downward. After that, it rises again along the sheet guide plate 31 and is nipped by the registration rollers 61 and 62. Immediately before that, the registration sensor 66 issues a paper end detection signal. By this detection signal, the minute kick roller 32 and the separating roller 41 are stopped. Then, after a short time, the registration rollers 61 and 62 start to rotate. Normally, at this time, the trailing edge of the sheet is still captured by the separation means 40, and the tension is gradually increased as the registration rollers 61 and 62 rotate.

However, the nip point R of the registration rollers 61 and 62 is
As shown in FIG. 9, FIG.
Not only does the pad 46 deviate upward than the extension of the tangent to the separating roller 41 at the contact point P between the pad 46 and the pad 46, but the tip of the pad 46 has a protruding portion 46a protruding downward. In accordance with the tension of the sheet, the leading end of the pad block 45 is lifted upward with the contact point P as a fulcrum, the contact point P also moves to the upstream side of the sheet feeding, and the angle of attack γ decreases. The play of the play 51a of the engaging portion 51 provided at the tip of the pad holder 47 as shown in FIG. 9 effectively contributes to the swing of the pad block 45.

The registration roller is moved by the upstream movement of the contact point P.
While the force of capturing the leading end of one sheet reaching the sheets 61 and 62 is reduced, the decrease in the angle of attack γ further strictly prevents the subsequent sheet and the subsequent sheets from entering.

The sheet fed by the registration rollers 61 and 62 is
The sheet is delivered to the transport unit 24 via the sheet guide 63, and the copying machine 1
Is positioned on the platen 3, the copying process is performed, and the sheet is discharged to the sheet discharge stacker 23 again by the action of the transport unit 24.

[Effects of the Invention] According to the present invention, a pad body is supported so that its tip end side swings with respect to the surface of the paper feed rotating body, and the pad is located on the tip end side of the contact point between the paper feed rotating body and the pad body. The following effects are obtained by protruding the body tip from the straight line connecting the contact point and the sheet nip point of the timing sheet feeding means toward the sheet feeding rotating body. First, when a sheet enters the paper feed rotating body, a constant pressing of the separating means is ensured by the urging means, so that multiple sheet conveyance at the initial stage of conveyance can be prevented. Next, the sheet conveyed by the paper feed rotating body is
Thereafter, the sheet is bent downward by the protrusion and nipped by the timing feeding means. However, the tension of the sheet between the timing feeding means and the separating means gradually increases, and as a result, the protrusion of the pad body Is lifted so as to gradually increase the pressing force of the urging means, thereby preventing double feeding of sheets. Furthermore, since the contact point moves upstream in the sheet feeding direction, that is, in the direction of the stacker of the sheet, the angle of attack of the sheet is also reduced, and the erroneous entry of the subsequent sheet is more severely restricted,
Demonstrates high separation performance. Then, the sheet once separated from the contact point of the separating means is released from tension, returns to the home position without lifting the pad body protrusion, and can accept the entry of the next sheet by the initial constant pressing. It becomes.

[Brief description of the drawings]

1 to 10 show one embodiment of the present invention, FIG. 1 is a longitudinal sectional view of a paper feeding unit, FIG. 2 is an enlarged view of a main part near a separating unit, FIG. 3 is a block diagram showing the entire sheet feeding apparatus, FIG. 4 is an overall view of the electronic copying apparatus, FIGS. 5 and 6 are views for explaining the operation of each separating means, and FIG. FIGS. 8, 8 and 9 are explanatory views of the operation of the sheet nipped by the registration roller, FIG. 10 is a timing chart, and FIGS. 11 and 12 are explanatory views of the main parts of the prior art. DESCRIPTION OF SYMBOLS 1 ... Electronic copying apparatus 2 ... Equipment main body 3 ... Platen 4 ... Paper feed cassette 5 ... Ejection tray 6 ... Exposure lamp 7 ... Mirror group 8 ... Lens block for zooming 9 ... Photosensitive drum 10 developing device 11 transfer device 12 fixing device 20 paper feeding device 21 body frame (device frame) 22 sheet stacker 23 discharge stacker 24 transport unit 30 Paper part 31: Sheet guide plate 32: Kick roller (feeding means) 35: Weight 36: Solenoid 37: Gate stopper 38: Solenoid 40: Separation means 41: Separating roller (feeding rotary member) 42 ... Rigid separating plate (first separating means) a... First passing gap 43... Elastic separating plate (second separating means) b... Second passing gap 45... Pad block (pad body) 46 …… Pad 47 …… Pad holder P point …… Separation roller and pad Contact point 46a Projecting part 50 Urging spring 51 Engaging part 51a Playback of engaging part s Distance between P point and engaging part α Angle of attack of rigid release plate β: Angle of attack at the tip of the pad γ: Angle of attack at the flat part of the pad 60: Resist space 61, 62: Resist roller (timing feeding means) 65: Empty sensor 66: Resist sensor Q point … Adhesion point of biasing spring R point …… Nip point of registration roller

Claims (2)

(57) [Claims] 1. A stacker for stacking and storing sheets, a feeding means for feeding a sheet in contact with the uppermost or lowermost sheet of the sheets stored in the stacker, and a feeding means provided downstream of the feeding means in the sheet feeding direction. A sheet feeding rotator that rotates in the sheet feeding direction; a pad body that presses against the sheet feeding rotator to prevent double feeding of sheets; and a biasing unit that presses the pad body toward the sheet feeding rotator. And a timing feeding means for receiving a sheet from the separating means and feeding the sheet at a proper timing. And a nip point of the sheet of the timing feeding unit, the tip of the pad body being closer to the tip side than the contact point between the paper feed rotating body and the pad body. Paper feeding apparatus being characterized in that projecting on the paper feed roller-side of the straight line connecting the. 2. A patent characterized in that a curved surface having a radius of curvature larger than the radius of curvature of the paper feed rotating body is provided at least on the leading end side in the paper feeding direction of the surface of the pad body facing the paper feed rotating body. The sheet feeding device according to claim 1.