JPH10226426A - Air suction type paper feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively separate paper sheets so as to prevent double feeding by causing an air flow blown into the upper layer part of the paper sheets stacked on a paper sheet mount base to come into contact with a paper sheet rear end aligning plate, to be inverted along its bent surface or an inclined surface and then retaining the rear end of the paper sheet of the uppermost layer. SOLUTION: An air suction type paper feeder includes a paper sheet mount base 1, a blowing means 2, a paper feeding means 3 and a suction means 4. In the rear part of the paper sheet mount base 1, a paper sheet end aligning plate 5 for aligning the rear ends of paper sheets P is erected so as to freely slid in the feeding direction. The upper stage part of the paper sheet rear end aligning plate 5 is inclined in the feeding direction and its tip part is formed to be bent. The flow of air blown to the upper layer part of the paper sheets P by the blowing means 2 is contacted with the paper sheet rear end aligning plate 5, inverted from its inclined surface 51 along a bent surface 52 and discharged in a lower direction to press the rear upper surface of the paper sheets P. Thus, air is expanded between the paper sheet P of the uppermost layer and a paper sheet P below it, the paper sheets P are effectively separated and thus double feeding is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an air suction type paper feeder provided in an image forming apparatus such as an electrophotographic copying machine.

[0002]

2. Description of the Related Art An air suction type sheet feeding device in which an air flow is blown onto a stacked sheet to float and separate the upper layer sheet, and the uppermost sheet is sucked and conveyed by vacuum suction means is, for example, It is described in JP-A-5-286596.

In this apparatus, a vertically movable pressing member is disposed between the feeding tension belt and the uppermost sheet, and the pressing member moves the uppermost sheet and the sheet below it. Thus, the airflow blown from the front is blocked, and the air is expanded to ensure the separation of both sheets.

[0004]

However, even in the case where the pressing member is provided as in the above-described conventional apparatus, the rear end aligning plate of the paper can be separately adjusted back and forth in order to align the rear end of the paper. Therefore, the space of the device is limited, the degree of freedom in designing the device is reduced, and the number of parts is increased, and the cost is increased.

The present invention has been made in view of such circumstances,
It is an object of the present invention to provide an air suction type sheet feeding apparatus which can use both a rear end alignment of a sheet and a press of a sheet with a simple configuration.

[0006]

According to the present invention, means for solving the above-mentioned problems are constituted as follows. That is, an air stream is blown against the front end of the upper layer paper stacked on the paper mounting table by the blowing means to float the paper, and the uppermost paper is sucked and conveyed by the suction means. In the air suction type sheet feeding device of the image forming apparatus, an upper end portion of a sheet trailing edge alignment plate erected at a rear portion of the sheet tray is formed in a curved or inclined shape in a sheet feeding direction, and Thus, the air flow blown by the above is reversed at the upper end of the sheet rear end aligning plate, and the upper surface of the uppermost sheet at the proper sheet feeding position is pressed down.

The air flow blown into the upper layer portion of the paper stacked on the paper mounting table abuts on the paper rear end aligning plate and reverses along the curved surface or the inclined surface, so that the rear end of the uppermost paper is adjusted. Pressing down, inflating the air between the uppermost sheet and the sheet below it, effectively sheets the sheet and prevents double feed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the air suction type sheet feeder of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a cross-sectional view of an air suction type sheet feeding apparatus, and FIG. 2 is an enlarged view of a main part. In these figures, reference numeral 1 denotes a sheet platform that is operated to move up and down, 2 denotes blowing means, 3 denotes sheet conveying means, Is a suction means provided inside the paper transport means 3, and a paper rear end alignment plate 5 for aligning the rear end of the paper P is slidably provided in the paper feeding direction at the rear of the paper mounting table 1. Has been established.

The upper end of the sheet trailing edge aligning plate 5 is inclined toward the sheet feeding direction, and the leading end is formed in a curved shape. The flow abuts on the sheet trailing edge alignment plate 5, is reversed from the inclined surface 51 along the curved surface 52 and is discharged downward,
Press down the rear upper surface of the paper P. Therefore, the uppermost sheet P
The air expands between the sheet P and the sheet P below the sheet P, thereby effectively separating the sheet P and preventing double feeding.

The lower part of the paper trailing edge alignment plate 5 is
Guided by a guide member provided in the paper feeding direction on the bottom of the
It can be fixed at a position corresponding to the size of the paper P, and has a rectangular opening 1 a opened at the rear of the paper mounting table 1.
3 (see FIG. 3), the rear end of the upper portion of the sheet P on the sheet table 1 raised to the sheet feeding position is brought into a state of being pushed out slightly forward while coming into contact with the inclined surface 51. Has its height set.

When the sheets P are initially stacked and placed on the sheet table 1 (see the two-dot chain line in FIG. 1) at the lower sheet supply position, the sheets P are thereafter placed on the vertical surface 53 of the sheet trailing edge alignment plate 5. Although the ends are in contact with each other and are vertically stacked, when the sheet mounting table 1 is lifted upward at the start of the sheet feeding operation, the rear end of the sheet P in the upper layer portion is in the above-described state. As described above, the sheet P of the upper layer is pushed out slightly forward as shown in the enlarged view of FIG.

As described above, in the state where the sheets are stacked slightly obliquely forward, the air flow from the blowing means 2 easily enters between the sheets P, and the separation between the sheets P, P is effectively performed. In addition to the separation of the uppermost sheet P and the sheet P thereunder, the sheet P below the sheet P is sufficiently separated in advance. Prevention of double feed is assured.

The curved surface 52 formed on the upper end portion of the above-mentioned paper rear end alignment plate 5 may be formed so as to be able to direct air flow downward, and may be formed in a bent shape. The inclined surface 51 is preferably formed so as to push the upper layer portion of the paper P forward slightly obliquely as shown in the figure. However, the inclined surface 51 may extend from the vertical surface 53 to the curved surface 52. The upper end of the sheet P may be curved or inclined so that the rear end of the sheet P can be pressed downward at the upper end of the sheet rear end aligning plate 5 so as to press the rear part.

The above-mentioned blowing means 2 comprises a blower 8 for generating an air flow at one end of a duct 7 having a rectangular cross section.
(See FIG. 3), the duct 7 is fixedly arranged at a position along the front surface of the paper loading table 1 at the uppermost position, and the spray ports 6,. At the same time, blow-up ports 9,... For preventing double feed are opened on the upper wall surface, and the other end side is closed.

On the other hand, the paper mounting table 1 is
4 (see FIG. 4), the paper P is automatically moved up and down according to the paper supply state (remaining amount of paper), and the paper P of the uppermost layer is always held at the height position corresponding to the blowing ports 6,. You. The position control is performed by detecting the height position of the uppermost sheet P by the sensor 11.
This is performed by controlling the driving source based on the detection signal. Note that the above-described sensor 11
May be a contact type or a non-contact type. The installation position may be appropriately selected as long as it can detect the uppermost layer of the sheet P. You may.

The winding electric mechanism 10 has an endless wire 20 wound around a pulley 13 connected to a driving source, driven pulleys 14 to 17 and tension pulleys 18 and 19. Are fixed to the paper platform 1 by brackets 21 and 22,
The sheet mounting table 1 is sequentially moved from a lowermost position (not shown) to an uppermost position (see FIG. 1) corresponding to the blowing port 6 via an intermediate position shown in the figure in a stepwise manner according to the state of sheet feeding. It has become. Note that, instead of the winding electric mechanism 10, the sheet mounting table 1 may be moved by, for example, an electric screw.

The sheet conveying means 3 includes a belt 33 with a hole wound between a driving pulley 31 and a driven pulley 32,
The suction unit 4 includes a suction box 34 connected to a suction pump 34 serving as a suction source, and the suction unit 4 is provided with openings 36 and 37 formed at a lower portion of the vacuum box 35. The air is sucked up, and the paper P is vacuum-adsorbed to the bottom surface of the belt 33 with holes.

As described above, the upper layer of the sheet P stacked on the sheet table 1 and located at the sheet feeding position is divided into a state in which the sheet P is easily sucked by vacuum. Since the air blown to the next sheet P is pressed by the downward airflow and expanded to separate the two sheets P, a separate sheet holding member is not required. On the other hand, in the process of transporting the sucked paper P, an air curtain is formed by the airflow blown up from the blowing ports 9,.
The leading end of the paper P below the vacuum-adsorbed paper P is prevented from advancing by the air curtain, and combined with the above-described sorting effect, more reliable double feed prevention is achieved.

[0019]

As described above, according to the air suction type sheet feeding apparatus of the present invention, the upper end of the sheet rear end aligning plate erected at the rear of the sheet table is curved in the sheet feeding direction. Since the air flow blown by the blowing means is inverted at the upper end of the sheet rear end aligning plate and presses the rear upper surface of the uppermost sheet at the proper sheet feeding position, Separately, the paper pressing member is not required, and the air expands between the uppermost paper and the paper under the uppermost paper, is effectively blown, and the double feed can be prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of an air suction type sheet feeding device of the present invention.

FIG. 2 is an enlarged view of a main portion of the paper trailing edge alignment plate.

FIG. 3 is an explanatory perspective view of the spraying unit and a sheet mounting table.

FIG. 4 is a configuration diagram of the air suction type sheet feeding device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Paper mounting board, 2 ... Blowing means, 4 ... Suction means, 5 ... Paper trailing edge alignment plate, P ... Paper.

Claims (1)

[Claims] 1. An airflow is blown by a blowing means to a front end of an upper layer sheet stacked on a sheet mounting table to float the sheet, and the uppermost layer sheet is sucked and conveyed by a suction means. In the air suction type sheet feeding device of the image forming apparatus, the upper end of the sheet trailing edge alignment plate erected at the rear of the sheet table is formed in a curved or inclined shape in the sheet feeding direction, The air flow blown by the blowing means is reversed at the upper end of the sheet rear end aligning plate, and presses the rear upper surface of the uppermost sheet in the proper sheet feeding position. Type paper feeder.