JPH069133A - Return mechanism - Google Patents

Abstract

PURPOSE:To provide a return mechanism which has a buffering member provided for a stopper against which paper collides when it is stopped, and can prevent with low costs bad printing due to skewing. CONSTITUTION:A return mechanism comprises a stopper against which the end of paper 3 transferred through a transfer passage 6 collides and stops, a buffering member 12 fitted to the stopper 9 and formed of an elastic material, a moving means 10 for moving the stopper 3 forward and backward relative to the transfer direction of the paper 3 to stop the stopper 3 in a position depending upon the size of the paper 3. After the end of the paper 3 transferred through the transfer passage 6 collides against the buffering member 12 and stops, the paper 3 is transferred in the reverse direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer for printing on both sides of a sheet, and more particularly to a folding mechanism having a buffer member for a stopper for stopping the sheet when the sheet is folded and conveyed for turning over. Is.

Recently, a printer has been widely used which has a mechanism for reversing the front and back sides of a printing sheet and prints on both sides of the printing sheet. In such a printer, when the printing paper is turned upside down after printing on one side, it is sent from the printer unit, temporarily stopped at the position corresponding to the size of the printing paper at the folding unit, and then returned in the opposite direction to send the paper. Although the paper is fed to the printer again by bypassing a different conveyance path, the printing paper collides strongly with the stopper at the folding back section, and the stopper tilts in the lateral direction, causing the printing paper to be skewed and conveyed as it is, resulting in printing failure. Therefore, a method for preventing this printing failure is desired.

[0003]

2. Description of the Related Art FIG. 4 illustrates an internal side view of a double-sided electrophotographic printing apparatus to which the present invention is applied. In the figure, 1 is a cassette mounting portion in which a cassette 2 is mounted, 2 is a cassette accommodating and accommodating printing paper (hereinafter referred to as paper) 3a of a desired size, 4 is a delivery roller, 5 is a printer portion, and 6a
6c is a conveying path, 7 is a folded portion, and 8 is a stacker.

The printer section 5 includes an optical unit 50, a photosensitive drum 51 as an image forming body, a cleaner 52, a charger 53, and a developing device.
54, a transfer device 55, a static eliminator 56, and a fixing device 57. In addition, a gate G1 is installed at the branch point of the transport paths 6a and 6c,
The folding part 7 is provided at the end of the conveying path 6a, that is, at the left end in the figure.

With this structure, the operation of printing on both sides of the paper 3a will be described. First, when the power of the apparatus is turned on, the fixing unit 57 is heated to a predetermined temperature to be in a printable state, and then there is a print instruction. Based on the signal, the sheet 3a is unwound from the cassette 2 in the direction of arrow A, conveyed on the conveying path 6a, and sent below the photosensitive drum 51.

By this time, the photosensitive drum 51 has been neutralized by the static eliminator 56, the residual toner has been cleaned by the cleaner 52, and has been recharged by the charger 53. Optical data emitted from an optical unit 50 including a laser light source scans the photosensitive drum 51, the electrostatic image formed on the photosensitive drum 51 is developed into a toner image by a developing device 54, and a transfer device 55 is formed.
After being transferred onto the sheet 3a by means of, it is fixed by the fixing device 57 and sent to the folding section 7.

The sheet 3a is temporarily stopped at the folding section 7, is sent in the opposite direction, is guided to the conveying path 4b, is turned upside down, is sent again to the printer section 5, and is printed and fixed on the back side in the same manner as described above. This time, the operation of the gate G1 guides the sheet to the conveying path 4c and conveys it to the stacker 8.

Here, FIGS. 5 (a) and 5 (b) explain the folded-back portion 7 with a plan view and a side view. As shown in the figure, rollers R1 to R3, paper top guide plate 70, frame 7
1, curved guide plate 72, feed screw 10a, feed screw 1
It is composed of a stopper 9a that is screwed to 0a and moves by rotation of the feed screw 10a, a pulse motor M, and a control unit 11.

When the cassette 2 is set in the cassette mounting portion 1 and the size of the paper 3a is detected by a sensor (not shown), the pulse motor M is rotated by the control of the control portion 11 and the stopper 9a is rotated by the feed screw 10a. Is moved and positioned at a position corresponding to the size of the paper 3a.

The rollers R1 to R3 are in rolling contact with each other, the roller R2 is connected to a motor (not shown), and the rollers R1 to R3 are rotated in the directions of the arrows in the figure by driving the motor. Therefore the paper
When 3a is fed in the direction of arrow B by the rollers R1 and R2, the leading edge of the sheet 3a collides with the stopper 9a and stops.
At this time, the trailing edge of the paper 3a just passed the rollers R1 and R2 and fell onto the guide plate 72 (this is the reason why the position of the stopper 9a was determined according to the size of the paper 3a). The end is clamped by the rollers R2 and R3, sent out in the direction of arrow C, and guided to the transport path 6b. Then, when the sheet 3a is conveyed through the conveying path 6b and is sent to the printer unit 5 again, the sheet 3a is turned upside down.

[0011]

According to the above-mentioned conventional method, when the paper is thick and hard, when it is sent to the folding part and collides with the stopper, when the leading edge of the paper hits the stopper by one side, there is a shock. The feed screw is bent, the direction of the stopper tilts in the lateral direction, and the sheet becomes slanted and stops. If the sheet is folded back and conveyed as it is, printing is performed as it is at an angle, which causes defective printing.

Therefore, if the strength of the feed screw or the stopper is increased in order to prevent the feed screw from bending, there is a problem that the mounting space is increased and the cost is increased.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a folding mechanism that can prevent printing defects due to skewing at low cost.

[0013]

FIG. 1 is a block diagram showing the principle of the present invention. In the figure, 3 is a sheet, 6 is a transport path, 9 is a stopper that is stopped by the leading edge of the sheet 3 transported through the transport path 6, and 12 is provided on the stopper 9 and is formed of an elastic material. The cushioning member 10 is a moving unit that moves the stopper 9 back and forth with respect to the conveyance direction of the sheet 3 and stops it at a position corresponding to the size of the sheet 3.

Therefore, after the leading edge of the sheet 3 conveyed through the conveying path 6 collides with the buffer member 12 of the stopper 9 and stops, the sheet 3 is conveyed in the opposite direction.

[0015]

The stopper 9 is moved by the moving means 10 and stopped at a position corresponding to the size of the sheet 3, and the conveying path 6
The front end of the paper 3 that has been conveyed is a buffer member of the stopper 9.
When it collides with 12, the shock is absorbed by the elastic force of the cushioning member 12, the shock to the stopper 9 is alleviated, the lateral inclination of the stopper 9 is prevented, and the sheet 3 stops without being skewed. Therefore, the sheet 3 can be folded and conveyed without skew.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to the folded portion described in the conventional example will be described with reference to FIGS. 2 and 3. The same reference numerals denote the same objects throughout the drawings.

The feed screw 10a and the leaf spring 12a in FIG. 2 correspond to the moving means 10 and the cushioning member 12 in FIG. 1, respectively. As shown in FIG. 2, the leaf spring 12 is attached to the stopper 9b of the folded portion 7a.
a is provided. Other configurations are similar to those of the conventional example described with reference to FIG.

As shown in the perspective view and side sectional view of the stopper of FIGS. 3 (a) and 3 (b), the leaf spring 12a is mounted on the front surface of the vertical portion of the inverted L-shaped stopper with a bending space a. ing.

Having such a structure, the operation will be described below. As described in FIG. 5 of the conventional example, the cassette 2
When is set, the pulse motor M is rotated by the control of the control section 11 and the feed screw 10a is rotated to position the stopper 9b at a position corresponding to the size of the sheet 3a. However, the position of the stopper 9b in FIG. 2 is set in consideration of the position of the front surface of the leaf spring 12a and the size of the sheet 3a that is deflected when the sheet 3a collides with the leaf spring 12a.

As shown in FIG. 2, the sheet 3a printed on one side and conveyed on the conveying path 6a has rollers R1 and R2 in the direction of arrow B.
When it is fed to the folded portion 7a by the paper, as shown in FIG.
And then stop. At this time, the impact is absorbed by the elastic force of the leaf spring 12a, and the sheet 3a stops without being inclined.

At this time, as shown in FIG. 2, the trailing edge of the sheet 3a has just passed the rollers R1 and R2 and has fallen onto the guide plate 72, and the trailing edge is clamped by the rollers R2 and R3 and is in the direction of arrow C. Then, as described in FIG. 5 of the conventional example, the sheet is guided to the conveyance path 6b and conveyed, the front and back sides are reversed, and the sheet is conveyed again to the printer section 5 for printing.

In this way, the stopper for the folded-back portion 7a
By providing the cushioning leaf spring 12a on 9b, the impact of the collision of the sheet 3a is absorbed by the leaf spring 12a, and the stopper
Since the impact on 9b is alleviated, the feed screw 10a is not bent, the lateral inclination of the stopper 9b is prevented, and the paper 3a does not stop diagonally, so that the skew when printing on the back surface is eliminated. It is possible to prevent the occurrence of printing defects.

In the above example, the case where the leaf spring 12a is used as the cushioning member has been described, but it goes without saying that another cushioning member, for example, a rubber plate or a sponge plate such as moltoprene may be used.

[0024]

As described above, according to the present invention, the stopper that stops when the leading edge of the sheet conveyed on the conveying path collides, and the buffer member attached to the stopper and formed of an elastic material And a moving unit that moves the stopper in the sheet feeding direction to stop at a position corresponding to the size of the sheet, and after the leading edge of the sheet conveyed on the conveying path collides with the buffer member and stops, By transporting the paper in the opposite direction, when the leading edge of the paper collides with the buffer member of the stopper, the impact of the buffer member is absorbed, the impact on the stopper is mitigated, and the lateral inclination of the stopper is prevented. In addition, since the sheet is stopped without being slanted, there is an effect that the sheet can be folded and conveyed without skewing.

[Brief description of drawings]

FIG. 1 is a block diagram of the principle of the present invention.

FIG. 2 is a side view showing an embodiment of the present invention.

FIG. 3 is an explanatory diagram of an example.

FIG. 4 is an internal side view of a double-sided electrophotographic printing device.

FIG. 5 is a configuration diagram showing a conventional example.

[Explanation of symbols]

3,3a is paper, 6,6a to 6c are conveying paths, 7,7a
Is a folded portion, 9, 9a, 9b are stoppers, 10 is a moving means,
12 is a buffer member, 12a is a leaf spring,

Claims (1)

[Claims] 1. A stopper (9) which is stopped by colliding the leading edge of a sheet (3) conveyed on a conveying path (6), and which is attached to the stopper (9) and is made of an elastic material. A cushioning member (12) and a moving means (10) for moving the stopper (9) back and forth with respect to the conveyance direction of the paper (3) and stopping it at a position corresponding to the size of the paper (3). , The leading edge of the paper (3) transported through the transport path (6) is the buffer member.
A folding mechanism configured to convey the sheet (3) in the opposite direction after colliding with (12) and stopping.