JPH06298384A - Paper feed control device for paper delivery section in image forming device - Google Patents

Abstract

PURPOSE:To prevent no feed regardless of some slips, improve the separation precision, and prevent the occurrence of double feed by applying the preliminary delivery handling control in addition to the one-delivery handling control for one copy. CONSTITUTION:The uppermost paper sheet S1 on a paper feed base 4A2 is extracted by a delivery roller 4A6, it passes through a handling feed controller and is sent to a conveyance roller 4A9, and the delivery roller 4A6 interrupts the delivery of the paper sheet S1 from the paper feed base 4A2 when its tip is detected by a downstream photo-sensor 85. The delivery roller 4A6 waits in the state to deliver the next paper sheet again before the paper delivery proceeds and its rear end is detected. The preliminary delivery time for the next sheet is set by a timer to the position where the tip of the paper sheet passes through a handling upper roller 4A7 and a handling lower roller 4A8 and it does not reach the conveyance roller 4A9 in the downstream area. No feed does not occur, and double feed can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for stabilizing a paper feeding device at a high speed in a paper feeding portion of an image forming apparatus.

[0002]

2. Description of the Related Art There is known a control means for repeating the paper feeding operation to feed the paper when the paper feeding portion of the image forming apparatus does not feed a predetermined amount due to slippage or the like due to normal feeding. As a result, the defective rate of paper feeding is reduced. However, in this case, the optical system or the exposed photosensitive drum generally takes a form of waiting until the paper is fed and then starting.

Further, a paper detection sensor is provided in the downstream region of the delivery roller, and the paper is fed to this sensor before normal paper feeding is started to realize a preliminary feeding system which stabilizes the paper feeding performance. is doing.

[0004]

In the above-described repetitive paper feeding method, the image formation is mainly performed on the paper, and the image formation is started based on the conveyance of the paper to the regular position as a reference. As a result, the predetermined copy capability will not be achieved.

Further, the preliminary feeding method ensures the accuracy of the paper feeding timing, but has no effect on the paper separating performance.

The present invention solves such a problem, prevents no feed even if there is some slippage, etc., and also improves separation accuracy and stabilizes without double feed. An object of the present invention is to provide a paper feed control device for a paper feeding unit of the image forming apparatus.

[0007]

This object is achieved by any one of the following technical means a, b, c and d.

(A) In the paper feed control device of the image forming apparatus paper feed section, which reverses the separation roller in the direction in which the paper is returned to prevent double feeding, in addition to the control for feeding and separating once for each copy A paper feed control device for a paper feed section of an image forming apparatus, characterized by performing preliminary feed handling control.

(B) In addition to the paper feed control device described in item (a), the feed roller is driven and stopped for a time set by a timer so that the paper slightly exceeds the separation roller of the separation unit during the preliminary feed separation control. At this time, the paper is returned to the position of the separation roller by rotating the upper and lower separation rollers in the direction of returning the paper, the paper feed control device of the image forming apparatus sheet feeding section.

(C) The preliminary feeding control is performed before the feeding of the next sheet is started by taking a signal that the trailing edge of the preceding sheet has passed the sensor position.
The paper feed control device of the image forming device paper feed section according to item b.

(D) The above-mentioned sending-out control is characterized in that when the preceding sheet receives resistance and is delayed and overlaps with the preliminary sending-out control of the next sheet, the normal sending-out control is prioritized. The sheet feeding control device for the image forming apparatus sheet feeding section according to any one of items a, b, and c.

[0012]

The separating roller is a reverse rotation driving roller to which a constant torque is transmitted through the torque limiter. When the feeding roller is not driven, the separating roller is pressed by the separating roller so that the paper is fed back. A separation feed control unit is configured together with a separation upper roller that is driven free.

When there is only one sheet S1 delivered from the sheet feeding cassette mounted on the sheet feeding table by the delivery roller, the torque of the separating upper roller for forward driving is limited to the torque of the lower separating roller. It has been defeated and sent out in the forward direction.

If not only one sheet S1 is sent by the delivery roller but also the sheet S1 is double-fed and sent, since the second and subsequent sheets S1 have the torque of the lowering roller through the sheet above them, Since the torque will not be lost to the upper roller, it will be pushed back and only the uppermost paper will be sent out in the forward direction.

However, still two sheets are still fed,
Not being able to send even one does not mean that it is eradicated, and there is anxiety that it may lead to such an accident with a little opportunity.

In consideration of such a point, the present invention gives a chance of normal feeding twice to the uppermost paper by giving not only one chance of feeding, but also the paper of less than that. The chance of being sent is doubled, but the chance of returning action is definitely increased, so that the certainty of sending one sheet, that is, the reliability is much improved.

Further, the cycle time of the paper feeding is hollow, that is, by incorporating the paper feeding in a time zone before the start of the normal paper feeding, the cycle time is not increased and the high speed is prevented. The high-speed single-wafer sheet feeding / conveyance can be performed reliably and reliably without causing any trouble.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in the accompanying drawings.

FIG. 1 is an overall configuration diagram including an optional device of an image forming apparatus (copier) to which a paper feeding device having a paper feeding control device of the present invention is applied. In the figure, 1
Is an automatic document feeder (ADF), 2 is a scanning exposure optical system,
3 is an image forming means, 4A, 4B, 4C and 4D are recording paper supplying means (paper feeding means), 5 is a recording paper conveying means, 6 is a fixing device, 7 is a paper discharge reversal switching conveying means, and 8 is for double-sided recording. A recording paper feed unit (ADU), 9 is a second recording paper supply unit, and 10 is a sorter for sorting and organizing the recording paper discharged from the copying machine main body. Further, the chain line in the figure indicates the conveyance path of the recording paper (transfer paper) S. FIG. 2 is an enlarged cross-sectional view of the main part of the recording paper conveying means of the copying machine. The upper body of the copying machine includes a scanning exposure optical system 2 arranged below a platen glass 21, a charger 32 around a photosensitive drum (image carrier) 31, a developing device 33, a transfer device 34, and a separator 35. An image forming means 3 including a cleaning device 36, a recording paper conveying means 5 for conveying recording paper on which an image has been formed by a belt, a fixing device 6, a paper discharge reversal switching conveying means 7, and a double-sided recording recording paper conveying means. (ADU). The lower main body of the copying machine is a paper feeding unit in which a plurality of recording paper feeding means (paper feeding means) 4A, 4B, 4C, 4D are arranged.

The upper sheet feeding device 4A includes a sheet feeding cassette 4A.
1 can be pulled out to the front side of the operator when the recording paper is replenished. Similarly, the sheet feeding cassette 4B1 is provided in the middle sheet feeding device 4B, and the sheet feeding cassette 4B1 is provided in the lower sheet feeding device 4C.
C1 is attached so that each can be pulled out. These sheet feeding cassettes 4A1, 4B1 and 4C1 have almost the same structure except that the heights and partition plates are different from each other according to the number of sheets of the recording sheets S1 to be stored, and therefore the upper stage is mainly used. The paper feed cassette 4A1 and the paper feed means will be described.

The upper sheet feeding device 4A includes a sheet feeding table 4A2 for accommodating the sheet feeding cassette 4A1 at a predetermined position and fixing it.
From a cassette unit composed of a movable bottom plate 4A3 in the housing of the sheet feeding cassette 4A1, a push-up lever 4A4 that pushes up the movable bottom plate 4A3 in a vibrating manner, a vibrating shaft 4A5 that vibrates and drives the push-up lever 4A4, and a drive unit (not shown). The recording paper push-up mechanism is composed of a feed roller 4A6, a separation roller 4A7, a separation roller 4A8, and a conveyance roller 4A9. The sheet feeding device 4B in the middle stage and the sheet feeding device 4C in the lower stage have the same configuration as the above-described sheet feeding device.

The feeding direction of the recording sheet S1 by each of the sheet feeding devices 4A, 4B, and 4C is toward the central portion of the copying machine main body on the right side in the drawing, and the recording sheet S1 conveyed from each sheet feeding device is , The guide plate 41 and the intermediate conveying rollers R4, R5 ascend substantially vertically, and further pass through the intermediate conveying rollers R3, R2 in the upper main body of the copying machine and then the registration rollers R.
To 1.

1000 to the downstream side in the sheet feeding direction by the three-stage sheet feeding devices 4A, 4B and 4C and further to the left in the drawing.
A large-capacity recording paper feed tray (LCT) 4D1 of a paper feeding device 4D capable of accommodating 3000 sheets of recording paper S2 is positioned on the elevating paper feed table and can be pulled out to the operator's front side when supplying recording paper. It has become. The LCT accommodates a small size recording paper of maximum size A4 (or 8.5 ″ × 11 ″).

Above the large-capacity recording paper feed tray 4D1, there is provided a paper feed mechanism similar to the above-mentioned paper feed mechanism (4A6 to 4A9), and the recordings stored in the paper feed tray 4D1. The paper S2 is fed from the upper layer to the left side in the drawing. The fed recording paper S2 is once lifted, made a U-turn, and horizontally transported, and then the intermediate stack tray 81 in the double-sided recording paper transport unit (ADU) provided in the upper main body of the copying machine. Is conveyed to the right in the horizontal direction by conveyance rollers R81, R82, and R83 provided below the sheet, and further rises again to join the conveyance paths from the above-described three-stage sheet feeding devices 4A, 4B, and 4C, and further, It passes through a conveyance path from the intermediate conveyance roller R2 to the registration roller R1.

A second recording paper feeding means 9 can be connected to the right side of the main body of the copying machine, and a three-stage paper feeding device 9 is provided.
A, 9B, 9C enables large-scale paper feeding of about 4,500 sheets. The three paper feed trays of these paper feed devices can also be pulled out to the front side of the operator when recording paper is replenished. The recording sheet S3 sent out from these sheet feeding trays by the sheet feeding means is conveyed to the upper main body of the copying machine through the intermediate conveying roller R9,
The intermediate transfer roller R2 reaches the registration roller R1.

Inside the paper feed passage formed by a pair of fixed / movable guide plates 41 and two pairs of intermediate conveying rollers R3, R4 provided on the left side of the three-stage paper feeding devices 4A, 4B, 4C. When a paper jam (jam) of the recording paper S1 occurs at, the movable guide plate 41 and the driven rollers R3 and R4 supported by the movable guide plate 41 are opened to the right to open the paper feed path to remove the jammed paper. It can be easily removed. When the movable guide plate 41 is opened, the right side surface of the main body of the copying machine has a space that can be opened, so that the movable guide plate 41 can be sufficiently opened to easily inspect the paper feed path and perform jam processing.
Even when the optional second recording paper feeding means 9 is connected to the main body of the copying machine, the movable guide plate 41 can be opened because there is a space below the connecting portion of the feeding means 9.

Further, the paper feed cassettes 4A1, 4B1, 4C
1, there is no recording paper conveyance path or paper feeding means between the large-capacity recording paper feed tray (LCT) 4D1 and the three paper feed cassettes 4A1 to 4C on the right side.
1 and the left-side paper feed tray 4D1 can be arranged close to each other, so that the main body of the copying machine can be made compact.

Furthermore, since a space without obstacles is formed on the left side of the large-capacity recording paper feed tray (LCT) 4D1 in the figure, a sufficient space for jam processing in the paper feeding means can be obtained.

Next, the handling control section will be described with reference to the side view of FIG. 3 and the drive transmission configuration diagram of FIG.

The frame 75 is a frame fixed to the main body frame. The frame 75 has a drive motor 51.
Further, a conveying roller 4A9 of a roller pair constituted by a torque limiter 52 and a driving roller directly connected to the driving roller and a roller pressed and driven by the driving roller is attached, and the drive is transmitted from the motor 51 by the wheels 63 and 64 and the belt. Further, the frame 75 is provided with a loosening roller 4A7 of a loosening feeding control unit, and drive is transmitted from a motor 51 through wheels 61 and 62, a belt wound around the wheels 61 and a clutch 56.

A lever 71 which is rotatable around the shaft center of the loosening roller 4A7 is provided, and a feed roller 4A6 is attached to the other end of the loosening roller 4A7.
A7 and delivery roller 4 A6 are wheel 58 and wheel 57
And the drive can be transmitted through the belt 59.

Although not shown in the figure, a solenoid is connected to the lever 71, and the feeding roller 4A6 attached to the lever 71 is disconnected from the contact with the sheet S1 on the sheet feed table 4A2 by energizing the solenoid. The paper feeding is disabled, and the feeding roller 4A6 comes into contact with the paper on the paper feed table 4A2 when the power is turned off so that the paper can be fed.

On the other hand, a frame 73 rotatable around the shaft center of the torque limiter 52 and the motor 51 is provided, and a lowering roller 4A8 is provided on the frame 73 and a gear 53 mounted on the shaft of the torque limiter 52. And lowering roller 4A
A gear 55 mounted on the eight shafts is drive-transmitted via an idle gear 54. In this way, reverse rotation torque of the lowering roller is generated.

The separation upper roller 4 of the separation lower roller 4A8
The pressing force on A7 is the spring applied between the spring hook 73A of the frame 73 and the hook 75A of the frame 75 fixed to the main body.
Caused by the bias of 79.

Further, the frame guide path has a transfer guide 81,
82 are provided.

Next, this operation will be described with reference to the timing chart of FIG.

The sheet (transfer sheet) S1 on the sheet feed table 4A2 is pulled out from above by the feed roller 4A6 which is capable of driving transmission due to the electromagnetic clutch 56 being turned on, passes through the sorting feed control section, and is conveyed to the conveying roller 4A9. When the photo sensor 85 of the paper detector provided downstream detects the leading edge of the paper, the sensor 85 is turned on, the feeding roller 4A9 continues to feed the sheet, and the trailing edge of the sheet is detected and turned off. become.

When the leading edge of the paper is detected and turned on, the sending roller 4A6 turns on a solenoid (not shown) that acts on the lever 71 that is its mounting frame, and the sending roller is lifted above the surface of the paper. And the electromagnetic clutch 56 is turned off, and the paper feed stand 4A
The feeding of the paper S1 from 2 is interrupted. The solenoid is turned off before the paper feed proceeds and the trailing edge is detected.
Then, it stands by again so that the paper can be fed from the paper feed table.

When the trailing edge of the paper is detected, the delivery electromagnetic clutch 56 is turned on and the pre-delivery control for the next paper is started. The preliminary feeding time is determined by a timer setting, and is set at a position where the leading edge of the paper does not reach the conveying roller in the downstream region after passing the positions of the upper separating roller and the lower separating roller.

By doing so, the above-mentioned no-feeding does not occur reliably and the double feed is prevented.

It should be noted that the raising and lowering of the sheet feeding table 4A2 is performed by a drivable area as shown in the figure.

[0042]

As described above, according to the present invention, the reliability of single-sheet feeding and double feeding prevention can be stably realized even in a high-speed sheet feeding state.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an image forming apparatus including a paper feed control device of the present invention.

FIG. 2 is an enlarged cross-sectional view of a sheet feeding unit of an image forming apparatus including the sheet feeding control device of the present invention.

FIG. 3 is a side view of the paper feeding unit in the present invention.

FIG. 4 is a drive transmission configuration diagram of a sheet feeding unit in the invention.

FIG. 5 is a timing chart of the paper feeding unit of the present invention.

[Explanation of symbols]

 4A Paper feeding device 4A1 Paper feeding cassette 4A2 Paper feeding stand 4A6 Feeding roller 4A7 Separation upper roller 4A8 Separation lower roller 4A9 Conveying roller 51 Motor 52 Torque limiter 53, 55 Gear 56 Electromagnetic clutch 58, 61, 62, 63, 64 Wheel 71 lever 73 frame (movable) 75 frame (fixed) 85 sensor S1 paper

Claims (4)

[Claims] 1. In a paper feed control device of an image forming apparatus paper feed unit, which reverses a separation roller in the direction in which paper is returned and prevents double feed, in addition to a control for feeding and separating each copy once. A paper feed control device for a paper feeding section of an image forming apparatus, which is characterized by performing preliminary feed handling control. 2. In addition to the paper feed control device according to claim 1, the feed roller is driven and stopped for a time set by a timer so that the paper slightly exceeds the separation roller of the separation unit during the preliminary feed separation control. At this time, the paper is returned to the position of the separation roller by rotating the upper and lower separation rollers in the direction of returning the paper, the paper feed control device of the image forming apparatus sheet feeding section. 3. The preliminary feeding and sorting control is performed before the feeding of the next sheet is started by taking a signal that the trailing edge of the preceding sheet has passed the sensor position. Alternatively, the paper feeding control device of the image forming device paper feeding unit according to claim 2. 4. The delivery control is such that, when the preceding sheet receives resistance and is delayed and overlaps with the preliminary delivery control of the next sheet, the normal delivery control is prioritized. Item 4. The sheet feeding control device for the image forming apparatus sheet feeding unit according to any one of items 1 to 3.