JP2685062B2 - Paper reversing mechanism in printing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper reversing mechanism necessary for printing on the back surface of paper in a printing machine.

[0002]

2. Description of the Related Art In order to turn over a sheet of paper, it is first necessary to eliminate the skew of the sheet of paper. Therefore, in the prior art, first of all, the sheet of paper passing through the heat roller is applied to a wall member provided in the middle of the conveying path. Then, the skew is removed, and then the sheet is sent to the duplex path and the wall member is moved to the retracted position.

[0003]

However, when the wall member is provided, there is a problem that it takes up space and the moving mechanism complicates the mechanism of the entire printing press. Therefore, an object of the present invention is to provide a paper reversing mechanism that makes the printing machine compact and simple.

[0004]

In order to solve the above problems, the paper reversing mechanism in the printing machine according to the present invention has a duplex path for reversing the paper in addition to the basic path for printing and discharging the paper. In a printing press having the drive path, the rotation of a paper ejection roller located near a branch point where the basic path and the duplex path are branched and located in front of a paper ejection direction is provided and provided near the branch point. A drive control device that drives and controls a switching device that can guide the trailing edge of the sheet from the basic path to the duplex path, and detects that the trailing edge of the sheet conveyed by the sheet discharge roller has reached a predetermined position. comprising sensors, a city which to transmit to the drive control unit, drive controller, depending on the progression timing of the paper
Stop the paper ejection roller for a specified time, and
Touch the paper to the eject roller to engage it to reduce the paper skew.
Correcting is a structural feature.

[0005]

The predetermined paper discharge roller near the branch point of the basic path is stopped by the drive control device, the paper on the front surface of which is conveyed and abutted against the above roller to remove the skew, and then the roller Is driven to advance the paper. At this time, the sensor detects that the trailing edge of the sheet has reached a predetermined position, and thereby stops the rotation of the roller. Further, the rear portion of the sheet is guided toward the duplex path by the switching device, and the roller having been reversely rotated can feed the sheet having the surface printed thereon toward the duplex path.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the embodiments shown in the accompanying drawings. FIG. 1 schematically shows a paper reversing mechanism in a printing machine. A basic path 12 and a duplex path 14 branch at a branch point 20.

The sheet P passing through the photosensitive drum 10 in the basic path 12 passes through a heat roller 16 which is a kind of a fixing device, and a drive control device 2 including a microcomputer or the like.
Forward rotation A, reverse rotation B, whose driving is controlled by 4,
Alternatively, it is conveyed toward the switchback roller 18 which can be stopped. The switchback roller 18 is essentially a paper carry-out roller, and is provided near the branch point 20 and apart in the discharge direction.

Generally, the sheet P passing through the heat roller 16 has a skew, and when the sheet P is transferred to the duplex path 14 for printing on the back surface of the sheet P, the skew must be corrected first. Therefore, the switchback roller 18 is stopped and the sheet P is abutted against the stopped roller 18 to remove the skew.

Thereafter, the switchback roller 18 is rotated in the forward rotation direction A under the control of the drive control device 24 so that the paper P
To the discharge direction. On basic path 12 and at branch point 2
A sensor 26 is provided at a predetermined position near the rear of 0, and the sensor 26 detects that the trailing edge of the paper P that is being discharged reaches the position of the sensor 26.
The signal is transmitted to the drive control device 24.

Upon receiving this signal, the drive control device 24 stops the rotation A of the switchback roller 18 and rotates the flipper 22 in the arrow direction. By the rotation of the flipper 22, the trailing edge of the paper P moves from the basic path 12 to the duplex path 14 and can be transferred. The time required for the movement of the paper path is short, and after the lapse of the short time, the switchback roller 18 is rotated in the reverse direction B by the drive control device 24.

As a result, the sheet P with no skew is generated.
Will be transferred to the duplex path 14 for printing the back surface. Although the flipper 22 is used as the switching device for moving the trailing edge of the sheet from the basic path to the duplex path in the above example, a guide member may be used instead to switch the guide direction. .

[0012]

As is apparent from the above description, according to the present invention, the skew of the sheet is removed by using the roller required for the sheet to be conveyed through the basic path, so that the wall having a large size can be removed. No members or the like are necessary, and the printing machine is compactly constructed accordingly. Also, it is mechanically simple.

[Brief description of the drawings]

FIG. 1 is a schematic view of a paper reversing mechanism according to the present invention.

[Explanation of symbols]

 12 ... Basic path 14 ... Duplex path 16 ... Heat roller 18 ... Switchback roller 20 ... Branch point 22 ... Flipper 26 ... Sensor

Claims (1)

(57) [Claims] 1. A basic path for printing and ejecting paper (P)
In addition to (12), in a printing machine having a duplex path (14) for reversing the paper, near the branch point (20) at which the basic path and the duplex path branch, and in the front of the paper discharge direction. Drive control of rotation of a certain paper discharge roller (18) and drive control of a switching device (22) provided near the branch point and capable of guiding the trailing edge of the paper from the basic path to the duplex path. a drive control unit (24) to the sensor the trailing edge of the sheet conveyed by the sheet discharge roller is transmitted to the drive control device detects that it has reached the predetermined position (26), comprises a capital, The drive control device (24) is used according to the timing of paper advance.
Stop the paper discharge roller (18) from rotating for a predetermined time, and
Make sure that the paper comes into contact with and engages the paper discharge roller (18), and
A paper reversing mechanism in a printing machine, which is characterized by straightening the sheet.