JPH02178116A - Sheet feeder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a sheet stacking means (hereinafter referred to as a paper feed tray) for stacking sheets used in image forming apparatuses such as copying machines and laser beam printers, and a feed rotation system. The present invention relates to a sheet feeding device that includes a body (hereinafter referred to as a sheet feeding roller) and a pressing member (hereinafter referred to as a weight) that presses and biases a sheet toward the sheet feeding roller.

[Conventional technology]

Conventionally, a sheet feeding device including a paper feeding tray, a paper feeding roller, and a weight is known, but in this device,
The sheet is pressed against the paper feed roller using only a constant weight, and the feeding force of the paper feed roller is increased by the friction between the sheet and the paper feed roller.
As stated in No. 92, adjust the weight according to the number of sheets,
The present applicant has proposed a sheet feeding device that is configured to switch in stages.

[Problem that the invention is trying to solve] However,
In the above conventional example, when a large number of sheets are loaded, the weight of the weight is constant, so the pressure is absorbed by the air layer between the sheets, and the pressure does not reach the lowest sheet, making it impossible to obtain sufficient feeding force. Delivery defects may occur. This tendency is particularly noticeable when feeding envelopes. In addition, when the number of loaded sheets decreases, the pressing force becomes excessive and double feeding may occur.Furthermore, in the above-mentioned proposal by the applicant, the position of weight switching of the weight (i.e., the height of the loaded sheets) Since the fixed position (in the horizontal direction) is fixed,
Depending on the size and type of sheet, there is a drawback that feeding failure or electric feeding is likely to occur when changing the weight of the weight. In addition, due to the structure for switching the weight,
It is necessary to increase the height dimension of the weight,
Accordingly, the height of the entire device has increased.

[Means for solving problems]

The present invention has been made to solve the above problems, and it is possible to always press sheets against a feeding rotary body with an optimal pressing force according to the number of sheets loaded, and also to reduce the weight of the device. An object of the present invention is to provide a sheet feeding device that can be downsized.

To achieve the above object, the present invention has a sheet stacking means for stacking a plurality of sheets, a feeding rotary body for feeding the sheets stacked on the sheet stacking means from below, and the sheet stacking means. A sheet feeding device comprising a pressing means for pressing the sheet against the feeding rotary body by contacting the uppermost sheet stacked on the sheet, wherein the pressing means is a weight having a constant weight and a loading amount of the sheet. This sheet feeding device is characterized by comprising a biasing means whose biasing force changes accordingly.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the sheet feeding device 1 is installed on the side of the laser beam printer 2 and above the cassette 3 that is detachably attached to the side of the printer 2. Positioning guide rods 5a and 5b provided at the base end are inserted into holes (not shown) drilled in the printer 2.
The guide rods 5a and 5b have grooves at their tips for locking the feeding device 1 to the printer 2. At the top of the cassette 3, a manual feed opening 2a is provided for inserting a manual sheet. Further, the sheet feeding device 1 has a paper feeding tray 6 for stacking sheets, and the tray 6 is provided with regulating plates 7a and 7b for regulating movement of the sheets in the width direction. Furthermore, a rack 9 is disposed below the width regulating plate 7a, and a rack 10 is disposed below the width regulating plate 7b. 1O is meshed with the pinion gear 11, thereby allowing it to move in the seat width direction. The paper feed tray 6 is provided with a sheet presence/absence sensor 12 that detects the presence or absence of sheets. OF
The photointerrupter 15 is configured by a photointerrupter 15 that is Further, on the downstream side of the sensor 2, a paper feed roller 16 is rotatably supported to feed the sheets stacked on the paper feed tray 6 from below, and above the roller 16,
A weight 17 that presses the sheet against the roller 16 is rotatably supported on pivot shafts 30a and 30b so that it can move up and down along arc-shaped holes 19a and 20a bored in the side plates 19 and 20. (See Figure 3). Further, a leading end regulating member 21 is disposed near the weight 17 to restrict the leading end of the sheets stacked on the paper feeding tray 6, and the lower end of the member 21 and the downstream end of the paper feeding tray 6 are connected to each other. are spaced apart by a predetermined distance, and sheets can be fed from this spaced apart portion 21a. Further, the leading edge regulating member 21 has a rib 21b to reduce friction with the sheet and prevent the leading edge of the sheet from becoming bent, and its ridge line is inclined by about 3 degrees toward the paper feed tray 6 side from the vertical line. There is. A separation pad 22 made of a high friction material such as rubber is fixed on a mounting base 23 at the bottom of the tip regulating member 21, and the pad 22 is fixed at a predetermined distance from the paper feed roller 16. They are spaced apart and are inclined at a predetermined angle with respect to the sheet feeding direction. Further, a flexible sheet-like member 24 is provided at a position facing the separation pad 22, and presses the sheets fed by the paper feed roller 16 in the direction of the separation pad 22 to prevent double feeding. . Further, a guide 25 for guiding the sheet is provided downstream of the separation pad 22, and a pair of conveying rollers 26 consisting of a drive port roller 26a and a pinch roller 26b is provided downstream of the guide 25. is installed. The separation pad 22 and the sheet-like member 24 are fixed on the same mounting base 23,
Further, the mounting base 23 can be easily removed downward.

Furthermore, a connector 27 is provided on the downstream side of the roller pair 26, and a connector (
(not shown), and performs all electrical connections between the printer 2 and the sheet feeding device 1.

Detection of whether the sheet feeding device 1 is attached to the printer 2 can be made on the printer 2 side by shorting two contacts on the connector 27.

FIG. 2 shows a state in which sheets S are loaded on the sheet feeding device 1, and the sheets S are pressed against the paper feeding roller 16 by the weight 17 (gravity and the tension of tension springs 29a and 29b, which will be described later). As the paper feed roller 16 rotates, the sheets are sequentially fed starting from the lowest position.
When the sheet S is present on the paper feed tray 6, the sensor lever 13 is rotated counterclockwise. Further, a photointerrupter 15 on a control board shown in FIG. 5, which will be described later, and one end 13a of the sensor lever 13 engage with each other to detect rotation of the lever 13.

3 and 4 show the state in which the weight is released by opening and closing the lid. In the figures, the lid 4 is rotatable around a hinge 52 fitted into holes provided in the side plates 19 and 20. There are hooks 8a and 8b on both sides. On the other hand, both ends of the weight 17 have holes 14c in the arms 14a and 14b.
, 14d with a certain degree of play (degree of freedom), and each engaging portion is prevented from coming out.

The arms 14a and 14b are rotatably locked at their other ends to hinge shafts 30a and 30b fixed to the side plates 19 and 20. There are spring hooks 53a, 53b near the center of the arms 14a, 14b, respectively, and guide rods 5a, 5.
A tension spring 29a is installed between the fixing fittings 28a and 28b of b.
, 29b are stretched. Also, the same (arm 14a
, 14b are fixed to dowels 18a, 18b, which are positioned to engage with the tips of the hooks 8a, 8b of the lid 4.

Next, the drive system will be explained with reference to FIGS. 5, 6, and 7.

In the figure, 31 is a drive side plate serving as the base of the drive system, 32
is fixed on a drive side plate 31 by a drive motor (in this embodiment, a pulse motor), and the drive side plate 31 also serves as a heat sink for the motor 32. In addition, the drive side plate 31 has a guide rod 5.
The fixing fitting 28b of b is fixed, and by bringing the tip of the guide rod 5b into contact with the frame of the printer 2,
The feeding device 1 is grounded.

[Transmission system from motor 32 to paper feed roller 16] The output of the motor 32 is transmitted through the gear 33 on the output shaft. Gear 34° 2nd gear 3
5. Gear 36. Gear 3 with one-way clutch 56
8, and drives the paper feed roller 16 which is rotatably supported by a sliding bearing 51 on the side plate 20 side and a metal bearing 49 on the side plate 19 side. The one-way clutch 56 locks and feeds the sheet when the motor 32 rotates in the direction of an arrow 57 (indicated by a solid line in FIG. 6), and when the motor 32 rotates in the direction of an arrow 58 (indicated by a broken line), it idles and feeds the sheet. 16 is inserted in a direction that does not rotate.

[Transmission system from motor 32 to conveying roller pair 26] The transmission system from the motor 32 to the gear 36 is the same as the transmission system from the paper feed roller 16, and will therefore be omitted. The transmission system from the gear 36 to the transport roller pair 26 is divided into two transmission systems.

The first system is gear 36. Gear 37. Gear 39. This is a transmission system in which driving force is transmitted in the order of gear 40 and gear 41 with one-way clutch 55 engaged. Here, the one-way clutch 55 rotates when the motor 32 rotates in the direction of the broken line 58, causing the drive roller 26a to rotate counterclockwise in FIG. 1. The second system performs transmission from the side plate 20 side using a gear 39 and a through shaft 47 that is prevented from rotating by a pin.

The through shaft 47 has a metal bearing 50 fitted to the drive side plate 31.
It is rotatably supported by a bearing 52 fitted to the side plate 20, and a gear 42 is prevented from rotating at the other end by a pin. Drive is transmitted from gear 42 to gear 45, which includes one-way clutch 54, via gears 43 and 43.

Here, the one-way clutch 54 is locked when the motor 32 rotates in the direction of the solid arrow 57, and the drive roller 26 is locked.
Rotate a counterclockwise in FIG.

Due to the first and second transmission systems, the rotation direction of the drive roller 26 is always counterclockwise in FIG. 1, regardless of the rotation direction of the motor 32. torsion coil spring 48a,
48b is coaxial with the through shaft 47 and inserted into bosses 19b and 20b that are part of the side plates 19 and 20, and one end thereof urges the shaft end 26C226d of the pinch roller 26b in the direction of the drive roller 26a, The other end is positioned using a dowel 19c provided on the side plate 19 or a support shaft 44a of a gear 44 provided on the side plate 20 as a stopper.

The locking portion of the lid 4 will be explained according to FIGS. 8, 9, and 1O. In the figure, reference numeral 59 denotes a leaf spring that urges a pin 60, which is retractably fitted into a hole in the side plate 19 (20), toward the inside of the side plate, and the tip of the pin 60 projects inside the side plate. Reference numeral 61 denotes a member connecting the lid 4 and the hinge 52 of the lid 4, and a hole 62 is bored at the tip thereof. In addition, the hole 62 is open when the lid 4 is open (opening angle 25
30°) at a position where it engages with the tip of the pin 60.

In the above configuration, when stacking the sheets S on the paper feed tray 6, first lift the lid 4 to enlarge the opening.
The hooks 8a and 8b are the dowels 18a of the arms 14a and 14b.
, 18b and pull it up, the weight 17 is lifted upward in conjunction with the opening operation of the lid 4, and the locking mechanism of the lid 4 stops the lid 4 at the open position, and at the same time the weight 17 also stops. Next, slide the sheet S onto the paper feed tray 6 and insert it until the leading edge hits the leading edge regulating member 21. When the lid 4 is closed, the weight 17 rides on the topmost sheet of the sheet S, and the weight 17 itself weight and spring 53a.

A pressing force acts in the direction of the paper feed roller 16 due to the biasing force of 53b. When the sheet S is inserted, the sensor lever 13
is pressed, and the presence of the sheet is detected. In response to a paper feed signal from the printer, a motor start signal is issued from the control board 46, and the motor 32 starts rotating in the direction of the arrow (solid line) 57 in FIG. 6, and the bottom sheet is fed out by the paper feed roller 16. The tip of the sheet is separated by the separation pad 22.
The sheets are separated one by one by coming into contact with them, and are sent to the next pair of conveying rollers 26. The motor 32 rotates in the direction of the arrow (dashed line) 58 in FIG. 6, that is, in the reverse direction, before the rear end of the sheet is fed into the pair of transport rollers 26 and the rear end of the sheet is removed from the feed roller 16. Then, only the conveying roller pair 26 is rotationally driven to further feed out the sheet. The paper feed roller 16 rotates as a result of the movement of the sheet.

Then, the motor 32 continues to rotate until the leading edge of the sheet is sufficiently pushed into the next conveyance roller (such as a paper feed roller of a printer) and passes through the conveyance roller pair 26, and then stops. Continuous paper feeding is performed by repeating the above operations. When the sheets S are fed in order from the bottom, the remaining sheets S gradually descend due to the biasing force of the weight and spring 29a, and at this time, the leading edge of the sheet rubs against the leading edge regulating member 21. However, since the ridgeline of the leading edge regulating member 21 is tilted toward the sheet S side than the vertical line, the leading edge of the sheet as the seat descends is aligned with the leading edge regulating member 21.
The leading edge of the paper does not become bent due to being pressed by the paper, and therefore paper feeding failures due to the leading edge of the paper do not occur. When the paper feed progresses further and reaches the final two sheets, the top sheet has a weight of 17.
A friction member 63 provided on the sheet contact surface side prevents paper feeding, and only the lower sheet is fed. When the last two sheets have been fed, the sheet presence/absence sensor 12 generates a sheet no signal, notifies the printer main body, and ends the sheet feeding operation.

Also, as the sheet decreases, the tension spring 29a.

29b is short (and the tension decreases. Therefore, weight 1
7 decreases as the pressing force sheet decreases.

[Embodiment 2] In FIGS. 11 and 12, the same numbers as in Embodiment 1 have the same functions, and the explanation thereof will be omitted. In the figure 1
7a are protrusions on both sides of the weight 17, and the side plates 19.2
The weight 17 is prevented from rotating so that it can move only in the vertical direction along guide elongated holes 19a and 20a provided in the guide elongated holes 19a and 20a, and is fitted into the guide elongated holes 19a and 20a. Furthermore, compression springs 29a are provided in the guide elongated holes 19a, 20a so as to bias the protrusion 17a of the weight 17 downward. Furthermore, to prevent the compression spring 29a from buckling and flying out, the guide elongated holes 19a, 2 are provided.
Spring retainers (not shown) are provided on both sides of Oa.

As is clear from the above configuration, the weight I7 and the compression spring 29
The same pressing force as in the first embodiment is generated on the sheet S by a. As the number of sheets decreases, the compression spring 29 becomes longer, and the biasing force against the weight 17 decreases.Therefore, as the number of sheets decreases, the pressing force by the weight 17 decreases.

〔Effect of the invention〕

As explained above, by providing a pressing means with a weight of a constant weight and a biasing means that generates a biasing force according to the loaded amount of sheets, ■ it is possible to apply an appropriate pressing force to the sheets according to the loaded amount of sheets. This enables stable paper feeding.

■ Since the size of the weight can be made small, the height of the entire device can be lowered.

[Brief explanation of the drawing]

FIG. 1 is a main sectional view of a first embodiment of the present invention. FIG. 2 is a sectional view showing a state in which sheets are stacked in the first embodiment of the present invention. FIG. 3 is a side view of the first embodiment of the invention. FIG. 4 is a side view of the first embodiment of the present invention (with the lid open). FIG. 5 is a perspective view of the first embodiment of the present invention. FIG. 6 is a side view of the drive side of the first embodiment of the present invention. FIG. 7 is an exploded view of the drive system of the first embodiment of the present invention. FIG. 8, FIG. 9, and FIG. 10 are detailed views of the locking portion of the lid according to the first embodiment of the present invention. FIG. 11 and FIG. 12 are diagrams of the second embodiment. 1 is a sheet feeding device, 4 is a lid, 5 is a guide bar, 6 is a paper feed tray, 7a and 7b are side pressers, 8a and 8b are hooks, 12 is a sheet presence/absence sensor, 14 is a weight arm, and I6 is a feeder. 26 is a pair of conveying rollers, and 29 is a spring.

Claims (1)

[Claims] (1) A sheet stacking means for stacking a plurality of sheets, a feeding rotary member for feeding the sheets stacked on the sheet stacking means from below, and a feeding rotary member for feeding the uppermost sheet stacked on the sheet stacking means. A sheet feeding device comprising a pressing means that presses the sheet against the feeding rotary body, the pressing means being a weight having a constant weight and a biasing force that changes depending on the loading amount of the sheet. A sheet feeding device characterized in that it is configured by means.