JPH0313435A - Paper feeding device - Google Patents

Abstract

PURPOSE:To always feed only one sheet by automatically changing the energizing force for energizing a retard roller to the feed roller side in response to the friction between the sheets and the friction between the sheet and a roller and the fluctuation of the torque of a torque limitter. CONSTITUTION:A shaft 10a of a retard motor 10 for giving the rotating torque to a retard roller 9 is driven so that the retard roller 9 is rotated reversely to the sheet feeding direction. At this stage, since the control force acts on the shaft of the retard roller 9, a housing of the retard motor 10 receives the rotating force in the direction reverse to the rotational direction of the shaft. This rotating force is transmitted to a plate 15, but since the rotation thereof is hindered by an fitting member 16, the plate 15 receives the rotary moment of which supporting point is the fitting member 16, and as a result, the retard roller 8 is energized to the feed roller 6 side. This energizing force is changed in response to a load acting on the retard roller 9, and the sheet is always fed out one by one.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a paper feeding device in a printer or the like.

(Prior Art) Conventionally, a paper feeding device is known that uses a pick-up roller to take out sheets of paper stored in a stacked state in a paper feed cassette one by one, feed them to a feed roller, and convey them to a printing position. However, since the stacked sheets are in close contact with each other, it is not uncommon for the pickup roller to pick up not only one sheet but two or more sheets. Therefore, in such a case, a retard roller is brought into elastic contact with the feed roller so that only one sheet of paper is conveyed from the feed roller, and the second and subsequent sheets are moved backward by the retard roller. (For example, US Pat. No. 4,368,881).

(Problem to be Solved) In the above conventional technology, the drive source for driving the retard roller is given by a drive motor that drives the photosensitive drum of the printer, and the rotational force is transmitted from this drive motor to the tart motor. This requires numerous parts such as electromagnetic clutches and gear trains. Furthermore, it is necessary to bring the retard roller into elastic contact with the feed roller with a predetermined pressure so that only one sheet of paper is conveyed. Therefore, there were problems in that the configuration became complicated and the cost increased.

An object of the present invention is to provide a paper feeding device that can bring a retard roller into elastic contact with a feed roller with a predetermined pressure with a simple configuration, and can reliably transport only one sheet of paper.

(Means for Solving the Problems) In order to achieve the above object, the paper feeding device of the present invention has the following features:
° A feed roller that feeds this paper in one direction is located downstream of the pickup roller that takes out the topmost paper stored in the paper feed cassette, and an arm that is biased toward this feed roller swings. The retard roller shaft is rotatably supported on this arm, and the retard roller shaft is rotatably driven by the retard motor in the opposite direction to the paper feeding direction. A retard roller is provided, and one of the plate and fixing member fixed to the retard motor is provided with an engagement member that engages with the other.

The axis of the retard motor and the retard axis may be the same axis.

Furthermore, long grooves extending in the radial direction of the retard motor are provided in the plate and the fixing member, respectively, and the engaging member is movably fitted into both long grooves, and the movement of one of the long grooves can be adjusted. Sometimes it is set up like this.

(Operation) The shaft of the retard motor that applies rotational torque to the retard roller is driven to rotate the retard roller in a direction opposite to the paper feeding direction. At this time, since a control force is acting on the shaft of the cutter roller, the housing of the retard motor receives a rotational force in a direction opposite to the rotational direction of the shaft. This rotational force is transmitted to the plate, but since its rotation is prevented by the engagement member, the plate receives a rotational moment using the engagement member as a fulcrum, and as a result, the retard roller is urged toward the feed roller side. become. This biasing force changes depending on the load acting on the tart roller, and one sheet of paper is always fed.

By adjusting the movement of the engaging member, the biasing force can be readjusted so that it always has a desired value.

(Example) Embodiments of the present invention will be described based on the drawings.

As shown in FIG. 1, paper sheets 2 are stored in a stacked manner in a paper feed cassette 1. As shown in FIG. A lift lever (not shown) is provided at the bottom of the paper feed cassette 1 and moves up and down in response to a paper feed command, and the paper 2 is moved up and down by this lift lever.

A pickup roller 3 is disposed above the left end of the paper feed cassette 1. The pickup roller 3 has a one-way clutch 5 connected to a shaft 4 that is rotationally driven by a paper feed command.
The pickup roller 3 can rotate in one direction clockwise (see FIG. 6).

A feed roller 6 is disposed downstream of the pickup roller 3 (left side in FIG. 1). The feed roller 6 is connected via a one-way clutch 8 to a shaft 7 whose drive is connected/disconnected by an electromagnetic clutch (not shown).The feed roller 6, like the pickup roller 3, can rotate in one direction clockwise. It is possible.

Registration rollers (not shown) are located downstream of the feed roller 6 to convey the paper 2 sent out from the feed roller 6 to a printing position.

A retard roller 9 is in elastic contact with the lower outer peripheral surface of the feed roller 6. As shown in FIG. 5, the retard roller 9 consists of a torque limiter 9a at the center and an elastic body (rubber) 9b fitted to the outer periphery of the torque limiter 9a. A retard roller 9 is provided.

A means for supporting the retard roller 9 and the retard motor 10 will be explained.

As shown in FIG. 1, the arm 12 is swingably supported by a pivot shaft 11.11 relative to a support plate 13, which is a fixed member. Vertical bent portion 12 integrated with this arm 12
a and 12b are formed, and the shaft 1 of the retard motor 10
0a is rotatably supported. The shaft 10a is prevented from moving in the axial direction by an earing or the like (not shown).

As shown in FIG. 1, a spring 14 is engaged between the vertically bent portion 12a of the arm 12 and a claw 13a formed by vertically bending the support plate 13.
A rotational force is applied in a counterclockwise direction (see FIG. 5) centering on . As a result, 1. The retard roller 9 is in elastic contact with the feed roller 6.

The retard roller 9 is moved in a direction opposite to the feeding direction of the paper 2 (
Rotational torque is applied in the clockwise direction (Fig. 5).

As shown in FIG. 2.3.4, a plate 15 is fixed to the retard motor 10.
The shaft 10a of the plate 15 and the opening 1 of the case 13
I am paying tribute to 3b.

The retard motor 1 is mounted on the plate 15 and the support plate 13.
Long grooves 15a and 13C extending in the radial direction of 0 are provided, respectively. The width of the long groove 15a of the plate 15 is
It is larger than that of the long groove 13c of No. 3.

A pin 16 serving as an engaging member is fixed to the long groove 13c of the case 13 with a nut 17. Threaded portion 16 of pin 16
The pin 16 has a small diameter, and by loosening the nut 17, the pin 16 can be moved along the long groove 13C. A pin 16 fixed to the support plate 13 projects through the long groove 15a of the plate 15. This allows plate 1
5 is prevented from rotating about the shaft 10a by the pin 16, and the plate 15 receives a rotational moment about the pin 16 as a fulcrum.

With this structure, a lift lever (not shown) lifts the bottom surface of the paper feed cassette 1 in response to a paper feed command, and presses the paper 2 against the pickup roller 3. The pickup roller 3 is rotated clockwise and picks up the topmost paper 2.
The paper 2 is taken out to the left by the frictional force between the feed roller 6 and the retard roller 9, and is fed between the feed roller 6 and the retard roller 9.

The paper 2 sandwiched between the feed roller 6 and the retard roller 9 is subjected to the rotational torque of both rollers 6.9.

Section 22 explains rotational torque.

First, consider the case where only one sheet 2 is taken out. In order for the paper 2 to be conveyed to the left by the clockwise rotation of the feed roller 6, μ P > RT (1
) “B. It is necessary to have something.

Here, μr = friction coefficient PB between the paper 2 and the retard roller 9: normal force with which the retard roller 9 presses the paper 2 (
Hereinafter referred to as "retard roller pressure." ) R: Radius of retard roller T: Torque limiter torque.

If the retard roller pressure PB and the torque limiter torque T are set so as to satisfy such conditions, one sheet of paper 2 can be conveyed to the left by rotation of the feed roller 6. In other words, the retard roller 9
Due to the frictional force μrPB received from the retard motor 1
It is rotated counterclockwise against the driving force RT from 0.

Two sheets of paper 2 in the paper feed cassette 1 may be taken out at the same time by the pickup roller 3. Therefore, a case will be considered in which two sheets of paper are taken out. 2
Among the sheets, the upper one is transported to the left by the clockwise rotation of the feed roller 6, and the lower one is transported to the right by the rotation of the retard roller 9 (toward the paper feed cassette 1 side). In order to return to , it is further necessary that RT>μ, pB (2), where μ is the coefficient of friction between two sheets of paper. If the retard roller pressure PB and torque limiter torque T are set so as to satisfy conditional expressions (1) and (2), the upper one of the two sheets
While the sheet is conveyed to the left by the rotation of the feed roller 6, the lower sheet can be returned to the right by the clockwise rotation of the retard roller 9. Thereby, only one sheet of paper can be conveyed by the feed roller 6 at any time.

Here, the retard roller pressure Pn will be explained.

The shaft 10a is driven by a retard roller 0 to rotate the retard roller 9 in a direction opposite to the feeding direction of the paper 2 (clockwise in FIG. 5). Since a braking force is acting on the shaft 10a in this state, the housing 10b of the retard motor 10 receives a rotational force in a direction opposite to the rotational direction of the shaft 10a (counterclockwise in FIG. 5). This rotational force is transmitted to the plate 15, but since the pin 16 is fitted into the long groove 15a, rotation of the plate 15 itself around the axis 10a is prevented, so the plate 15 uses the pin 16 as a fulcrum. As a result, the retard roller 9 is urged toward the feed roller 6 side. This biasing force becomes PB of conditional expressions (1) and (2) explained earlier.

Furthermore, retard roller pressure PB and torque limiter torque T
The relationship will be explained with reference to FIG.

From the balance of moments around the pivot axis 11, if the clockwise direction is taken as a negative value, then T(R-Lsln θ)
+F (L -L2)A I
Pi +F L -P L cos θ-WL3-0
(3) The relational expression 8 4 Bl holds true.

Here, TA: Return force of torque limiter 9a F: Reaction force W that the bin 16 receives from support plate 13: Retard roller 9, retard motor IO, and plate 15
Self-weight of the entire unit including Distance L between the acting centers of gravity: Distance θ from the center of the pivot shaft 11 to the latching portion of the spring 14: An angle of inclination between a horizontal line passing through the shaft 10a and a straight line connecting the shaft 10a and the center of the pivot shaft 11.

Here, since the set torque of the torque limiter 9a is T, TAR (4) holds true,
And from the balance around plate 15, FPL, , -T
(5) holds true. If the torque limiter pressure PB of these conditional expressions (3), (4), and (5) is expressed by the expression of the torque limiter return force TA, then P = (F e L 4 - W La ) /
(L t cos θ) + (R/ L 2 ) T A
/cosθ (6).

In conditional expression (6), (R/L 2-s in θ)/cos θ-K
(81)(F L −WL )/(L
cosθ)-P (62)8 4 3
If 1 BO, it can be expressed as PB - KTA + PBO (63), where PB is in a proportional relationship with TA.

Here, if conditional expressions (1) and (2) explained earlier are satisfied,
This results in an area in which both rollers 6.9 feed only one sheet of paper 2. That is, (T / μ )>PB> (
TA/μ, ) (7) If the retard roller pressure PB is set to satisfy P, then
Only one sheet of paper 2 will be sent.

Here, the variation range of each factor is 0.75≧μP≧0.3 (8) 1.6
≧μ ≧1.0 (9) It has been experimentally determined that 600 ≧T^≧300 [gf] (10), and if the diameter R of the retard roller 9 is 25 [■l], The operating diagram shown in Fig. 7 is obtained.In this operating diagram, the conditional expression (63
) can be set so that it passes through the one-sheet feeding area, and the slope K of the straight line passing through the center can be set to 1.1 as an appropriate value. Therefore, the values of R9θ and L2 may be set so that -1,1 in conditional expression (61).

L2 is calculated from equation (61) as L2-R/ (Kcosθ+slnθ)=R/ (1,
1 cos + sin θ) (84).

In conditional expression (63), the value of PBo is such that the operating line is TA
It is preferable to set it so that it falls within the range of one-sheet feed even within the variation range of .

The value of L2, and thus the position of the bottle 16, can be adjusted by loosening the nut 17 shown in FIG. If the diameter R of the retard roller 9 changes due to wear, the bin 1
By adjusting the position of 6, the value of K can be readjusted to the optimum value.

FIG. 7 shows another embodiment, in which the plate 11
The opening width of the long groove 115a of 5 is the same as that of the long groove 1 on the support plate 113 side.
1 (which is smaller than that of c), and the pin 11B serving as the engaging member is fitted with the nut 11 in the long groove 115a of the plate 115.
Fixed by 7. The bottle 11B fixed to the plate 115 protrudes through the long groove 113c of the support plate 113, and the plate 115 is configured to be prevented from rotating around the shaft 110a, and the movement of the bottle 116 can be adjusted by loosening the nut [17]. Possible configurations are substantially the same as in the first embodiment.

FIG. 8 shows still another embodiment, in which a retard shaft 209c of a retard roller 209 and a motor shaft 210c of a retard motor 210 are constructed as separate members. A retard shaft 209c and a motor shaft 210c are each rotatably supported on the arm 212.
Motor pinion 210 fixed to motor shaft 2toc
d, and a gear 209d fixed to the retard shaft 209c.
The retard roller 209 is rotated by a retard motor 210 in a direction opposite to the direction in which the paper 2 is fed. The configuration in which the plate 215 is fixed to the retard motor 210 and the rotation of the housing 210b of the retard motor 210 is prevented by the support plate 213 and the bin 21B is similar to the first embodiment. This is substantially the same as the second embodiment. In FIG. 8, a braking force acts on the retard shaft 209C, and the housing 210b of the retard motor 210 receives a rotational force in a direction opposite to the rotational direction of the motor shaft 210c. This rotational force is transmitted to the plate 215, but the bottle 21G is
13c, the plate 215 itself is prevented from rotating around the motor shaft 210c.
The plate 215 receives a rotational moment about the bin 216 as a fulcrum, and as a result, the retard motor 210 is lifted upward in the plane of the paper in FIG. oscillate. Therefore, the retard roller 209 moves in one direction in the plane of FIG. 8, and the retard roller 209 is urged toward the feed roller (not shown).

In the present embodiment, the movement of the engagement member 16 is made adjustable, but it is preferable that the bin 16 be fixedly erected on one of the plate 15 or the support plate 13, and a hole into which the bin 16 fits is provided on the other. It may be a set-up.

Further, a spring 14 is provided as a means for causing the feed roller 6 to spring the retard roller 9, and an eccentric weight is provided on the arm 12, and this weight applies a counterclockwise rotational force around the pivot shaft 11. You can do it like this.

Furthermore, although torque is applied to the retard motor 9 by providing the torque limiter 9a, it is also possible to maintain the generated torque of the motor itself constant by providing a current limiting circuit or the like in the drive circuit of the retard motor 10. .

(Effects) As described above, according to the paper feeding device of the present invention, the biasing force that biases the retard roller toward the feed roller side is caused by the friction between the sheets, the friction between the roller and the paper, and the fluctuation of the torque limiter torque. It is possible to maintain a wide stable region in which only one sheet of paper is fed at any time.

Furthermore, by making the position of the engaging member movable and adjustable, the biasing force that biases the retard roller can be adjusted to the optimal value in order to cope with fluctuations in the diameter of the retard roller or the diameter of the feed roller due to friction. can do.

[Brief explanation of the drawing]

Figure 1 is a partially omitted perspective view, Figure 2 is an exploded perspective view of the main parts,
Figure 3 is a front view of Figure 2, Figure 4 is a sectional view taken along line A-A in Figure 3, Figure 5 is a front view showing the direction in which force acts, Figure 6 is an operating diagram, and Figure 7. is an exploded perspective view of main parts showing another embodiment,
FIG. 8 is a sectional view of main parts showing still another embodiment. DESCRIPTION OF SYMBOLS 1...Paper feed cassette, 2...Paper, 3...Pickup roller 6...Feed roller, 9209...Retard roller, 9c...Retard roller shaft, to, 110, 210... Retard motor, 10a,
110a, 210a--shaft of retard motor, 12.
212...Arm, 13.113,213...Fixing member (support plate), 13
c, 113c, 213c - Long groove, 15.115,
215...Plate, 15c, 115c, 215c・
...Long groove, 16.118.216...Engagement member (pin). Above Figure 2 Long groove Figure Figure TA variation range

Claims (3)

[Claims] (1) A pickup roller that takes out the uppermost sheet of paper stored in the paper feed cassette, and a feed roller that is located downstream of the pickup roller and feeds the sheet of paper in one direction, and is supported so as to be able to swing freely. On the other hand, the arm is biased toward the feed roller, the shaft of the retard motor is rotatably supported by the arm, and the retard roller shaft is rotatably supported by the arm. and a retard roller rotationally driven by the retard motor in a direction opposite to the paper feeding direction, a plate fixed to the retard motor, and a plate provided on one of the plate and the fixing member so as to engage with the other. What is claimed is: 1. A paper feeding device comprising: an engaging member; (2) The paper feeding device according to claim 1, wherein the axis of the retard motor and the axis of the retard roller are the same axis. (3) In claim 1 or 2, the plate and the fixing member are each provided with a long groove extending in the radial direction of the retard motor, and the engaging member is provided so as to be movable in one of the long grooves. and is fitted into the other of the long grooves.