JPH0677162B2 - Automatic duplex copier - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mechanism for preventing double-sheet feeding during backside copying of an automatic double-sided copying machine.

<Prior Art and Its Defects> FIG. 4 shows a schematic structural diagram of a conventional automatic double-sided copying machine. The copying machine main body A is placed on a cabinet B, and a sorter C is attached to the left side of the copying machine main body A and the cabinet B. A photoconductor drum 1 is arranged substantially in the center of the copying machine main body A. From a paper cassette 2 inserted from the right side of the copying machine to a paper feed roller 3, a paper feed timing roller 4, a transfer section, a conveyor belt 7, a fixing device. 8 and a paper transport path extending to the paper discharge roller 9 are formed. The transfer portion is composed of the photoconductor drum 1 and a transfer charger 6 facing the photoconductor drum 1, and sequentially transfers the toner image on the surface of the photoconductor drum 1 rotating at a constant speed to a copy sheet moving at a constant speed. The paper discharged from this paper conveyance path is fed into the sorter C, and a sorting flapper 10 is installed near the entrance of the sorter C to direct the fed paper to either the reverse conveyance path 12 or the bin 11. Sort. Of these, the paper that has been transported in the reverse transport path 12 with its direction reversed for backside copying is in cabinet B.
It is temporarily stored in the intermediate tray 13 formed inside.
When a predetermined number of front side copies are completed and back side copying is performed, the paper stored in the intermediate tray 13 is moved toward the paper feed timing roller 4 by the intermediate tray paper feed rollers 14 and 15 installed on the right side of the intermediate tray 13. It is fed.

This intermediate tray paper feed roller is composed of an upper roller 14 and a lower roller 15, and at the time of paper feeding, the upper roller 14 rotates in the forward direction (clockwise in the figure) so that one sheet at the upper end is fed.
Then, the lower roller 15 reverses (counterclockwise in the figure) in the direction opposite to the paper feeding direction in order to prevent the two sheets of paper accumulated below from being fed. This prevents the two sheets of the plurality of sheets stored in the intermediate tray 13 from being fed. A backside copy sheet conveying path 16 is formed between the intermediate tray sheet feeding rollers 14 and 15 and the sheet feeding timing roller 4. The sub-conveyance path is formed from the distribution flapper 10, the reversal conveyance path 12, the intermediate tray 13, the backside copy paper conveyance path 16 to the paper feed timing roller 4.

When a sheet is fed from the intermediate tray 13 for back side copying, the sheet is conveyed through the back side copy sheet conveying path 16 until the leading edge of the sheet reaches the sheet feeding timing roller 4. When the leading edge of the paper reaches the paper feed timing roller 4, the paper sensor 5 notifies the control unit of the fact. After this notification, when the transfer preparation for the copying process is completed, the paper feed timing roller 4 conveys the paper to the transfer portion at the constant speed and the transfer is performed.

By the way, the transfer process is performed by sequentially transferring the toner image formed on the surface of the photosensitive drum 1 rotating at a constant speed to the paper moving at a constant speed as described above. The speed is kept constant by the rotation of the paper feed timing roller 4 at a constant speed. Therefore, after the paper feed timing roller 4 starts to feed the paper to the transfer portion, it is desirable that the other rollers are not in contact with this paper so as not to brake the paper feed. For example, in the case of the paper feed roller 3 that conveys paper from the paper cassette 2 to the paper feed timing roller 4, it is configured by a so-called half-moon roller having a cutout portion on the roller surface, and rotates once at the start of copying to rotate the paper cassette 2 After the inner sheet is conveyed to the sheet feed timing roller 4, the notch is directed toward the sheet to avoid contact with the sheet.

On the other hand, in the case of the intermediate tray paper feed rollers 14 and 15, the distance for which the paper has to be conveyed is longer than that for the paper feed roller 3 and it is impossible to convey the necessary distance in one rotation, so that the intermediate tray paper feed rollers 14 and 15 are constituted by half moon rollers. I can't do it. Therefore, when the paper fed from the intermediate tray 13 reaches the position of the paper feed timing roller 4, it is desirable that the trailing edge of the paper is separated from the intermediate tray paper feed rollers 14 and 15, but it is currently common. The copying machine can copy up to A3 size, and if you try to put the A3 size sheet in the back side copy paper transport path 16 in the standby mode, this back side copy paper transport path 16
Requires a length longer than the length of the A3 size (about 42 cm). However, providing such a long conveyance path in the copying machine is against the flexibility of the copying machine, which is desired to be downsized.

Therefore, when the paper feed timing roller 4 starts to feed the paper to the transfer unit, other rollers including the intermediate tray paper feed rollers 14 and 15 are used as the paper to be conveyed so as not to hinder the paper feed speed control. The length of the paper that is fed from the intermediate tray (than the length of the maximum copy size) is either driven or by a mechanism that does not brake the paper transportation by a one-way clutch in the paper transportation direction. Shorten the length of the backside copy paper transport path 16 (intermediate tray paper feed rollers 14, 15-
It is possible to make the distance of the paper feed timing roller 4 shorter than the length of the maximum size paper).

However, when the drive control of the intermediate tray paper feed rollers 14 and 15 is performed in this way, the lower roller 15 that has prevented the two-sheet feeding in the carrying process up to that point becomes rotatable. Therefore, if the trailing edge of the fed paper has not yet passed through the intermediate tray paper feed rollers 14 and 15 (for back side copying with the maximum size paper), the lower roller 15 also follows the paper being conveyed. Then, due to friction, the next sheet may also be fed into the back side copy sheet conveyance path 16 and fed by two sheets.

<Object of the Invention> An object of the present invention is to provide an automatic double-sided copying machine in which double-sheet feeding does not occur even if the back side copying paper conveyance path is shortened.

<Structure and Effect of the Invention> The present invention is directed to a reversing conveyance path for reversing the conveyance direction of a single-sided copied sheet branched from a sheet discharge section, an intermediate tray for temporarily storing the reversed sheet, and a temporary storage in the intermediate tray. The distance between the intermediate tray paper feed roller that feeds the selected sheets one by one and the paper feed timing roller that is located immediately before the copying process unit is set to be the maximum length that can be copied by the copier. In an automatic double-sided copying machine provided with a sub-conveyance path consisting of a single-sided copied sheet conveyance path, a paper feeding direction is provided on the intermediate tray at a position distant from the paper feeding timing roller by the copyable maximum length or more. A sheet feeding auxiliary roller that is driven to rotate is provided in the intermediate tray, and when the length of the sheet fed from the intermediate tray is equal to or more than the length between the intermediate tray sheet feeding roller and the sheet feeding timing roller, Eye with the trailing edge of the paper is to pass through the paper feed auxiliary roller is driven to rotate by pressing the paper feed auxiliary roller on one sheet of paper on the intermediate tray,
It is characterized in that a means for stopping the rotation drive of the sheet feeding auxiliary roller after the rear end of the first sheet has passed the sheet feeding auxiliary roller is provided.

With the above configuration, according to the present invention, the length of the paper stored in the intermediate tray is longer than that of the back side copy paper transport path, and even if the transport of the paper by the paper feed timing roller is started, the intermediate tray paper feed roller If the trailing edge of the intermediate tray feeds, the intermediate tray paper feed roller is driven and controlled in the free state as in the past, but since the paper feed auxiliary roller holds the paper directly below, Never be. As a result, the size of the entire apparatus such as a copying machine is reduced, and even if the back side copy paper conveyance path is shortened, the trailing edge of the conveyed paper does not pull out the next paper and feed two sheets. Can occur, which can contribute to downsizing of the apparatus and improve the reliability of the copying machine.

<Embodiment> FIG. 1 is a schematic configuration diagram of an automatic double-sided copying machine according to an embodiment of the present invention. In this figure, the difference in the configuration from the automatic double-sided copying machine shown in FIG. 4 is that the paper feed auxiliary roller 26 is installed on the intermediate tray. The feeding distance between the feeding auxiliary roller 26 and the feeding timing roller 4 is longer than the maximum copying length of the copying machine A, and the feeding distance between the intermediate tray feeding rollers 14 and 15 and the feeding timing roller 4 is the above. It is set shorter than the maximum copy length of the copying machine A.

FIG. 2 shows a schematic configuration diagram in the vicinity of the intermediate tray of the above embodiment. The intermediate tray feeding upper roller 14 is attached to the shaft 31 via a one-way clutch (not shown). The one-way clutch allows the shaft 31 to freely rotate the upper roller 14 in the sheet conveying direction (arrow D in the figure). With this one-way clutch, when the rotation speed of the upper roller 14 due to the rotation of the shaft 31 is faster than the moving speed of the paper, the upper roller 14 rotates together with the shaft 31 to move the paper in the paper conveyance direction, and the paper rotation is faster than the above rotation. When the moving speed of the sheet is high, the upper roller 14 is adapted to follow the movement of the sheet. As a result, the conveyance of the sheet is not hindered. Driving force is transmitted from the drive shaft 33 to the shaft 31 via the clutch 20. This drive shaft 33 has a gear
21 is attached to the gear 21, a gear 22 is meshed with the gear 21, and the shaft 32 of the gear 22 has a clutch 23 and a gear 24.
And are attached. That is, the transmission of the power transmitted to the gear 22 to the gear 24 is opened and closed by the clutch 23.
The intermediate tray upper roller 14 is divided into left and right parts, and an arm 27 and a gear 25 are installed between them.
Both the arm 27 and the gear 25 are rotatably supported on the shaft 31. The arm 27 extends on the intermediate tray 13 in the direction opposite to the paper conveyance direction, and a paper feed auxiliary roller 26 is attached to the tip end thereof. The paper feed auxiliary roller 26 is connected to the gear 25 and the belt 28, and rotates by receiving the driving force transmitted through the gears 21 and 22, the clutch 23 and the gears 24 and 25. The rotation direction is the paper conveyance direction. The arm 27 is moved up and down by the solenoid 30 and the lever 29. One end of a lever 29, which is rotatable at a fulcrum 29a, is locked near the tip of the arm 27, and the other end is connected to the solenoid 30. That is, when the solenoid 30 is driven and the movable part is pulled, the laver 29 pulls the arm 27 downward.

Although not shown in the figure, the intermediate tray lower roller 15 is also driven by a shaft similarly to the intermediate tray upper roller 14, but the driving direction thereof is opposite to the sheet conveying direction.
The lower roller 15 is attached to the shaft via an electromagnetic clutch that is turned off by the output of a paper feed timing roller drive signal described later.

FIG. 3 is a timing chart showing control signals at the time of back side copying of the maximum copyable size paper. When the back side copying process is started, first, the clutch 20 that drives the intermediate tray paper feed rollers 14 and 15, the clutch 23 that drives the paper feed auxiliary roller 26, and the solenoid 30 that presses the paper feed auxiliary roller 26 against the paper are turned on. One of the upper ends of the sheets of paper stored in the intermediate tray 13 is fed and conveyed to the backside copy sheet conveying path 16. At this time, since the intermediate tray feeding lower roller 15 is rotating in the opposite direction, the two-sheet feeding is not performed. When the leading edge of the conveyed paper reaches the paper feed timing roller 4 and is detected by the paper sensor 5, the paper feed timing roller 4 is turned on 0.2 seconds after the detection and the clutch 23 for driving the paper feed auxiliary roller is turned off. To do. However, at this time, the trailing edge of the sheet is still hooked on the intermediate tray sheet feeding rollers 14 and 15, so that the clutch 20 that drives the upper roller 14 is turned on. On the other hand, the lower roller 15 stops reverse rotation and is driven by the electromagnetic clutch to be rotatable, so that it does not hinder the sheet conveyance. For this reason, the lower roller 15 does not fulfill the function of preventing double-sheet feeding, but the trailing edge of the conveyed sheet has already passed the sheet feeding auxiliary roller 26, and the sheet feeding auxiliary roller 26 is Touching the next sheet. At this time, the paper feed auxiliary roller 26 stops rotating, and the solenoid 30 presses the paper until the paper being conveyed is separated from the intermediate tray paper feed rollers 14 and 15, so that the next paper is sold on the conveying path. It will not be done. The intermediate tray feeding roller 14 is stopped and the solenoid is turned off by a controller that stores the sheet size.

As a result, even when performing double-sided copying with a sheet having a length of the backside copying sheet transporting path 16 or more, it is not necessary to feed two sheets at the time of backside copying, and the working accuracy of the copying machine can be improved. .

[Brief description of drawings]

FIG. 1 is a schematic structural diagram of an automatic double-sided copying machine according to an embodiment of the present invention, FIG. 2 is a diagram showing a structure near an intermediate tray of the above embodiment, and FIG. It is a figure which shows the control signal of. FIG. 4 is a schematic structural diagram of a conventional automatic double-sided copying machine. 26: Paper feed auxiliary roller, 30: Solenoid.

Claims (1)

[Claims] 1. A reversing conveying path for reversing the conveying direction of a single-sided copied sheet branched from a sheet discharging section, an intermediate tray for temporarily storing the reversed sheet, and one sheet temporarily stored in the intermediate tray. One-sided copy completed, with the distance between the intermediate tray paper feed roller feeding each sheet and the intermediate tray paper feed roller from the paper feed timing roller located immediately before the copying process section set to the maximum copying length of the copying machine or less. In an automatic double-sided copying machine provided with a sub-conveyance path consisting of a paper conveyance path, a feeding roller that is rotationally driven in the paper feeding direction at a position on the intermediate tray that is separated from the paper feeding timing roller by at least the maximum length that allows copying. A paper auxiliary roller is provided, and when the length of the paper fed from the intermediate tray is equal to or greater than the length between the intermediate tray paper feeding roller and the paper feeding timing roller, the trailing edge of the first paper is Previous Together to pass through a paper feed auxiliary roller is driven to rotate by pressing the paper feed auxiliary roller on one sheet of paper on the intermediate tray,
An automatic double-sided copying machine comprising means for stopping the rotation drive of the sheet feeding auxiliary roller after the trailing edge of the first sheet has passed the sheet feeding auxiliary roller.