JPH03216422A - Sheet feeding device - Google Patents

Abstract

PURPOSE:To prevent the double feed of sheets due to excessive insertion of the sheet or the defective feed of the sheets by protruding a tip blocking member to the feed belt side by means of a sheet absent signal from a sheet detecting sensor and moving aside the tip blocking member by means of a sheet present signal. CONSTITUTION:A sheet feeding device is provided with a tip regulating member 9 to regulate and match the tip of a sheet S and a sheet detecting means 5 to detect the presence of the sheets S on a sheet loading means 3. In the sheet feeding device, when the absence of the sheet is detected by the sheet detecting means 5, a tip blocking member 7 with which the tip regulating member 9 is formed is moved to a position below a sheet loading lowermost surface. By eliminating a gap between the tip regulating member 9 and the sheet loading lowermost surface, the sheet tips are trued and reliable loading is effected. When the presence of the sheets is detected by the sheet detecting means 5, the tip blocking member 7 is moved upward so as to part from the sheet loading lowermost surface by a specified distance, and the sheet S is brought into a state to be fed from the sheet loading means 3. This constitution prevents the occurrence of a trouble, e.g. the double feed or the defective feed of the sheets S.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention relates to a sheet feeding device used in image forming apparatuses such as copying machines and laser beam printers.
More specifically, the present invention relates to a sheet feeding device that ensures alignment of leading edges of sheets stacked on sheet stacking means.

(B) Conventional technology Conventionally, in a sheet feeding device that sequentially feeds the sheets stacked on a sheet stacking means (sheet stacking table) one by one from the bottom side, a feeding roller and a separation pad are used. It has been considered that a simple structure may be used to separate and feed sheets one by one. In this sheet feeding device, a constant gap is always formed between the regulating plate that regulates the leading edge of the sheet and the sheet stacking table on which the sheets are stacked, and the sheets to be fed are first Two or three sheets are separated in the gap, and only the lowest sheet is separated and fed by a separation pad placed immediately after the separation.

(c) Problems to be Solved by the Invention However, in the above-mentioned sheet feeding device, when replenishing sheets onto the sheet stacking table, the sheet bundle is inserted through the opening of the sheet feeding device, especially when inserted forcefully. case,
Some of the sheets on the bottom side may enter the gap between the leading edge regulating plate and the sheet loading table and reach the vicinity of the separation pad, making it easy for sheets to be fed in duplicate, or some sheets may be stuck to the leading edge regulating plate. If the sheet is forcibly packed between the sheet and the feeding roller, it is likely that the sheet will be fed incorrectly.

Therefore, the present invention detects the absence of a sheet on the sheet stacking means using a sheet detection means, eliminates the gap between the leading end regulating member and the lowest sheet stacking surface, and provides a sheet feeding system that ensures the reliable stacking of sheets. The purpose is to provide a device.

(:) Means for Solving the Problems The present invention has been made in view of the above-mentioned circumstances, and as shown in FIGS. 1 to 3, for example, a sheet loading means for loading sheets (S) is provided. (3) and the sheet loading means (3);
), a feeding rotary body (6) that sequentially feeds the sheets (S) stacked on the sheet (S) from below, a tip regulating member (9) that regulates the tip of the sheet (S), and the sheet stacking means (3). ), a sheet feeding device (1) comprising: a sheet detection means (5) for detecting the presence or absence of a sheet (S) stacked on a sheet; A member (7) is provided on the feeding rotary body (6) side so as to be movable forward and backward;
When the front sheet detection means (5) detects that the sheet (S) is in no state, it moves the leading end blocking member (7) to a position beyond the lowest sheet stacking position, and removes the sheet (S). The present invention is characterized by having a moving means (11.66) for moving the leading end blocking member (7) to a certain distance from the sheet stacking lowest surface position when the "present state" of S) is detected. (e) Effect Based on the above configuration, when the sheet detecting means (5) detects that there is no sheet (S) on the sheet stacking means (3), the leading end blocking member (9) The member (7) moves to a position below the lowest sheet stacking surface, and in this state, all the leading ends of the sheets (S) to be supplied come into contact with the leading end regulating member (9) and are aligned. Further, when the presence of the sheet (S) is detected by the sheet detection means (5),
The leading end blocking member (7) of the leading end regulating member (9) moves a certain distance away from the lowest sheet stacking surface, and the sheet (S) can be fed from the sheet stacking means (3).

Note that the above-mentioned symbols in brackets are for referring to the drawings, and do not limit the structure of the present invention in any way.

(F) Example A first example of the present invention will be described below with reference to FIGS. 1 to 3.

In the figure, a sheet feeding device 1 is detachably attached to a manual paper feeding port of an image forming device 2, and sheets fed from the sheet feeding device 1 as described later are transferred to the image forming device 2. The image forming apparatus 2 is configured to be conveyed to an image forming section (not shown) in the image forming apparatus 2 by a conveying roller 12 therein.

The sheet feeding device 1 has a sheet loading table (sheet loading means) 3 on which sheets S are loaded. A sheet detection sensor (sheet detection means) 5 for detecting the presence or absence of a sheet S is disposed at a suitable position on the sheet stacking table 3, and the sheet detection sensor 5 is pivotally mounted at its intermediate portion by a shaft 39. A sensor lever 40 that rotates in contact with the seat S, and a photointerrupter 41 that is turned on and off by its lower end.
It is composed of.

A plurality of feeding belts (feeding rotary bodies) 6 are arranged on both sides of the sheet detection sensor 5 to feed the sheets S loaded on the sheet stacking table 3 from below. , is suspended between a drive pinion 43 fixed to a drive shaft 42 and a driven pulley 46 fixed to a shaft 45, and is rotatable. A weight (pressing member) 47 is arranged above the feeding belt 6, and a pin 49 integrated with the weight 47 is connected to a long hole 50a formed in a pair of side plates 50 of the sheet feeding device 1.
It can be raised and lowered by extending from the shaft and attaching it to the tip of a lever (not shown).

Near the downstream side of the weight 47, a tip regulating member 9 for regulating the tip of the sheets S stacked on the sheet stacking table 3 is disposed. The leading edge regulating member 9 includes a leading edge regulating plate 51 fixed to the main body of the sheet feeding device 1, and a leading edge blocking member 7 attached to the leading edge regulating plate 51 as described later. The lower end of the tip regulating plate 51 and the feeding belt 6 are spaced apart from each other by a certain distance A, so that the sheet S can be fed from this space.

A separation pad 52 made of a high-friction material such as rubber is fixed on the downstream side of the tip regulating member 9, and this separation pad 52 is spaced a predetermined distance from the feed belt 6 and It is inclined at a predetermined angle with respect to the feeding direction.

A slidable tip blocking member 7 is provided on the opposite side of the tip regulating plate 51 from the sheet contacting surface in parallel with the tip regulating plate 51. A member 9 is constructed. An arm member 7a (third
A compression spring 55 is compressed between the engagement member 53 (see figure) and the engagement member 53 fixed to the main body of the sheet feeding device 1, and urges the leading end blocking member 7 downward. A flag 7b that engages with a photointerrupter 10 solidly attached to the main body is provided at the upper end of the tip blocking member 7.
It is now possible to detect the top position of the

The cam 11 with which the arm member 7a is pressed is formed integrally with a shaft 59 whose both ends are rotatably attached to the side plate 50 and the support plate 60, as shown in FIG. Drive is transmitted from a gear 57 via a clutch 56. The cam 11 has a one-way clutch 56
As a result of this action, it is designed to rotate only in the direction of the dashed arrow 28 in FIG.

The gear 65 meshing with the gear 57 is connected to the feeding belt 6.
The driving pulley 43 is attached to the fixed driving glaze 42 via a one-way clutch 63. Furthermore, this gear 65 meshes with a gear 67 that is fixed to the output shaft of a pulse motor 66 that is fixed to the support plate 60 and is rotatable in forward and reverse directions. Note that when the pulse motor 66 rotates forward or backward, the drive shaft 42 rotates only in the direction of the solid arrow 62 in FIG. 3 due to the action of the one-way clutch 63.

In the sheet feeding device configured as described above, when the sheet S is replenished onto the sheet stacking table 3, the sensor lever 40 is pushed down by the sheet S, and the sheet detection sensor 5 detects that the sheet is present. ” is detected, and this detection signal causes the pulse motor 66 to rotate in the direction of the broken line arrow, and at the same time, the arm member 7 is rotated by the cam 11 rotating in the direction of the broken line arrow 61.
Push a up from the position shown in Figure 1 to the position shown in Figure 2.

The tip blocking member 7 integrated with the arm member 7a moves away from the feeding belt 6 as shown in FIG. 2, and only then does a gap appear between the tip blocking member 7 and the feeding belt 6. , the sheet feeding device 1 becomes ready for feeding. In this state, when a sheet feeding command is received to the sheet feeding device 1, the pulse motor 6
6 rotates in the direction of the solid arrow, the drive shaft 42 rotates in the direction of the arrow, and the sheet S is fed from the lowest position.

Next, when all the sheets S on the sheet stacking table 3 are fed, the sheet detection sensor 5 detects that there is no sheet,
The pulse motor 66 is once again driven by a predetermined pulse in the direction of the broken line arrow in FIG. 1, the gap between the leading end blocking member 7 and the feeding belt 6 disappears as shown in FIG. Therefore, even when the sheet S is inserted into the sheet stacking table 3, the leading end blocking member 7 restricts the leading end of the sheet S to be inserted, thereby preventing the sheet S from being pushed in too much.

FIG. 4 shows a second embodiment of the invention, in which the same functions as those in the first embodiment are denoted by the same reference numerals, and the explanation thereof will be omitted.

In the figure, a tip blocking member 7 is slidably attached to the tip regulating plate 51 as in the first embodiment.
The pin 51a is fitted into a long hole drilled in the tip regulating plate 51 and guided. Further, the leading end blocking member 7 is provided with an arm 16, the leading end of which is connected to the sheet feeding device 1.
It is connected to a solenoid 15 configured in the main body of the
When the solenoid 15 is OFF, the tip blocking member 7
is pushed down to the lowest position by the elasticity of the compression spring 55, as shown in FIG. 4, and the space between the tip blocking member 7 and the feeding belt 6 is closed.

When the sheet S is replenished onto the sheet stacking table 3, the sheet detection sensor 5 detects the presence of the sheet, and this detection signal turns on the solenoid 15, causing the tip blocking member 7 to
is lifted, and the sheet feeding device 1 becomes ready for feeding. In this state, a sheet feeding command is issued to the sheet feeding device 1, and the sheet S is fed.

5 to 7 show a third embodiment of the present invention. In the figures, the same functions as those in the first embodiment are denoted by the same reference numerals, and the explanation thereof will be omitted.

In the figure, the swing guide 20 disposed near the inside or outside of the plurality of feeding belts 6 is connected to the sheet loading table 3.
It protrudes upward through a hole (not shown) drilled in the hole, and its lower end can be engaged with the photointerrupter 22. The swing guide 20 is rotatably supported by a shaft 70 and biased counterclockwise in the figure by tension springs 71 that are respectively engaged with the swing guide 20 at both ends and the main body of the sheet feeding device 1. Due to the elasticity of the tension spring 71, the lower edge of the swing guide 20 is
It is in pressure contact with the circumferential surface of the eccentric cam 23 fixed to the shaft 72.

At the uppermost position, the swing guide 20 protrudes above the feed belt 6 and comes into contact with the weight 47, and the hook portion 21 formed at its tip connects the lower end of the tip regulating plate 51 with the feed belt 6. The gap is closed, and at the lowest position, it is sunk below the feed belt 6 as shown in FIG.

In FIG. 7, a gear 75 is fixed to the drive shaft 25 of the feed belt 6 via a one-way clutch 73, and is configured to rotate only in the direction of the solid arrow.

The gear 75 is connected to the pulse motor 2 via the idle gear 76.
It meshes with the drive gear 77 of No. 6. Furthermore, the upper drive gear 77 meshes with a gear 82 via an idle gear 80, and this gear 82 is attached via a one-way clutch 81 to the shaft 72 to which the eccentric cam 23 is fixed. As a result, the eccentric cam 23 is moved only in the direction of the broken line arrow by the action of the one-way clutch 81. The swing guide 20 has the lowest position as its home position, and when it is in this position, the swing guide 20
The lower end of the photointerrupter 22 blocks the optical path of the photointerrupter 22.

In the sheet feeding device configured as described above,
When the sheet detection sensor 5 detects the absence of a sheet, the pulse motor 26 rotates clockwise (in the direction of the dashed arrow) by a certain angle to rotate the eccentric cam 23 to the position shown in FIG. The movable guide 20 rises to the uppermost position shown and stops.

Next, a seat S is placed between the weight 47 and the swing guide 20.
is inserted and pushed until its tip abuts the tip regulating plate 51, the sheet detection sensor 5 detects the presence of a sheet, and this detection signal causes the pulse motor 26 to further rotate clockwise to the home position. This rotation of the pulse motor 26 causes the eccentric cam 23 to rotate from the position shown in FIG. 5 to the home position shown in FIG.

At this point, the lowermost surface of the stacked sheets S comes into contact with the feeding belt 6 and is pressed and urged by the weight 47, and the sheet feeding device 1 becomes ready for feeding. When the pulse motor 26 rotates clockwise, the one-way clutch 73 acts so that no drive is transmitted to the feeding belt 6.

Next, when a paper feed signal enters the sheet feeding device 1, the pulse motor 26 rotates counterclockwise (in the direction of the solid line arrow), and the feeding belt 6 feeds the sheet S at the lowest position. send During this feeding operation of the sheet S, no driving force is transmitted to the eccentric cam 23 due to the action of the one-way clutch 81, and the eccentric cam 23 maintains its position. Eventually, when the sheet S runs out, the sheet detection sensor 5 detects the absence of a sheet and returns to the initial operation, allowing the sheet to be inserted. The sheet S sent out by the feeding belt 6 is separated by a separation pad 52, and then transferred to the sheet feeding device 1.
The sheet S sent out is delivered to the next conveyance roller, for example, the conveyance roller 12 in the image forming apparatus 2.

In this embodiment, the swing guide 20 is moved in and out by controlling the rotational direction of the pulse motor 26, without providing a new actuator for opening and closing the gap between the tip regulating plate 51 and the feeding belt 6. allows opening and closing.

Further, since the tip of the swinging guide 20 in the sheet conveyance direction has a hook portion 21 bent upward, the swinging guide 20 and the tip regulating plate 51 are at the highest swinging position of the swinging guide 20. is a sheet S that overlaps in a comb-like shape and eliminates gaps.
This prevents the tip from protruding. Further, at the lowest position of the swing guide 20, the tip of the hook portion 21 is connected to the feeding belt 6.
The sheet S is located below the feed belt 6.
feeding is carried out without any problem.

(G) Effects of the Invention As explained above, according to the present invention, the sheet absence signal from the sheet detection sensor that detects the presence or absence of the sheet S is used to detect the presence of the sheet S.
By protruding the leading edge blocking member that prevents the leading edge of the sheet from protruding toward the feed belt and retracting the leading edge blocking member in response to a sheet presence signal, electric feeding or feeding of sheets caused by over-insertion of sheets during sheet feeding can be prevented. It becomes possible to completely prevent feeding defects.

[Brief explanation of drawings]

FIG. 1 is a longitudinal side view of a sheet feeding device in a state without a sheet, showing a first embodiment of the present invention, FIG. 2 is a longitudinal side view of the sheet feeding device in a state with a sheet, and FIG. 4 is a longitudinal cross-sectional side view of a sheet feeding device showing a second embodiment of the present invention, and FIG. 5 is a longitudinal cross-sectional view of the sheet feeding device in a sheetless state showing a third embodiment of the present invention. A side view, FIG. 6 is a longitudinal side view showing a state with a seat, and FIG. 7 is a side view showing the drive system. S... Sheet, 1... Sheet feeding device 2...
・Image forming apparatus 3...Sheet loading table (sheet loading means) 5...Sheet detection sensor (sheet detection means) 6...Feeding belt (feeding rotating body)
7...Tip blocking member 9...Tip regulating member
11...Cam 51...Tip regulation jFi
55...Compression spring, 66...Pass motor

Claims (1)

[Scope of Claims] 1. A sheet stacking means for stacking sheets, a feeding rotary body for sequentially feeding the sheets stacked on the sheet stacking means from below, and a tip regulating member for regulating the tip of the sheet. and,
A sheet feeding device comprising: sheet detection means for detecting the presence or absence of sheets loaded on the sheet stacking means, wherein a leading end blocking member forming a part of the leading end regulating member is moved toward and away from the feeding rotating body. If the front sheet detection means detects that the sheet is in an "absent state", the front end blocking member is moved to a position beyond the lowest sheet stacking position, and the sheet is detected as being in a "presence" state. In this case, the sheet feeding device further comprises a moving means for moving the leading end blocking member to a certain distance from the lowest sheet stacking position.