JPH07178989A - Device for clamping rear end of sheet and ink jet recording apparatus using the same - Google Patents

Abstract

PURPOSE:To prevent a sheet from being loosened with a simple mechanism when the sheet is wound around a drum, and clamp the rear end of the sheet in response to the lengths of a plurality of sheets. CONSTITUTION:A device is provided with a drum 1, which has a front end clamp member 2 disposed on the peripheral surface of the drum to grip a front end of a sheet, and a sheet rear end clamp member 3 supported rotatably on a drum shaft 1a and disposed in the vicinity of the drum surface. Sheet drawing members 3a and a clutch claw 3b, each being provided on the sheet rear end clamp member 3, prevent a sheet from being loosened and clamp the rear end of the sheet in response to the lengths of various kinds of sheets.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet trailing end clamp device in an image recording apparatus such as a copying machine, a printer or a facsimile machine, which winds a sheet of paper or synthetic resin film around a drum and forms an image on the sheet. .

Further, the present invention relates to an ink jet recording apparatus equipped with a sheet trailing edge clamp device.

[0003]

2. Description of the Related Art In an apparatus that winds a sheet around a drum and rotates the sheet to record an image, it is necessary to securely clamp not only the leading edge of the sheet but also the trailing edge.

For example, in an ink jet recording apparatus, when an image is formed with a slack occurring when a sheet is wound around a drum, the distance between the sheet and the recording head changes and the flight distance of the ink changes, resulting in a change in image quality. And, in the worst case, the loosened sheet hits the recording head, causing damage to the recording head, stains on the sheet, jamming, and the like. As a method for solving such a problem, the structures described in JP-B-55-13912 and JP-A-50-118809 are known. In these devices, the former is a method of penetrating the rear end of the seat with a locking member composed of a needle or a pin and winding it around the drum, and the latter is a method in which an intake hole is formed on the drum peripheral surface corresponding to the rear end of the seat. It is a method in which the rear end of the sheet is wound around the drum by the suction force of the suction device provided.

In recent copying machines or printers, it has become common to selectively supply sheets of a plurality of sizes and form an image on the sheets. The structure described in Japanese Patent Laid-Open No. 63-183866 is known. This mechanism consists of a side plate mechanism that detects the paper width and a sheet trailing edge clamp mechanism that moves in conjunction with this.The side plate is adjusted to the width of the set sheet, and the sheet trailing edge clamp member works in conjunction with this. This is a method in which the trailing edge of the sheet is clamped by moving a fixed amount.

[0006]

However, in each of the above configurations, in the configuration of the first publication, a needle hole is formed at the rear end of the sheet. Further, in the configuration of the second publication, when some kind of accident such as a power failure occurs, the suction operation is stopped, and once the sheet is separated from the intake hole, the suction operation is not accurately restored and the sheet is separated from the drum. There is a problem that it will end up. In addition, the configuration of the third publication has a drawback that not only the type of paper is limited due to the limitation of the moving position, which corresponds to the length of paper, but the clamp mechanism becomes complicated and expensive. It was

The present invention solves this problem and an object thereof is to eliminate the above-mentioned drawbacks and to provide a device for clamping the rear end of the seat with a simple structure. Another object of the present invention is to provide a mechanism for easily and reliably winding a sheet around a drum and clamping a plurality of sheets in an ink jet recording apparatus.

[0008]

SUMMARY OF THE INVENTION A sheet trailing edge clamping device of the present invention is a sheet trailing edge clamping device for a sheet wound around a drum, the drum having a leading edge clamping member for gripping the leading edge of the sheet on the drum peripheral surface, A sheet rear end clamp member rotatably supported on the drum shaft and disposed near the drum surface, and a sheet ironing member for pressing the sheet on the drum peripheral surface on the sheet rear end clamp member; , A clutch pawl installed so as to simultaneously rotate the drum and the sheet rear end clamp member when abutting on the drum surface.

In an ink jet recording apparatus that ejects ink droplets to obtain an image, the recording head that selectively ejects ink droplets to form an ink image on a sheet faces the recording head with a gap. A sheet clamp device having a drum, a sheet feeding member for feeding a sheet, and a sheet discharging member for discharging a printed sheet, wherein the sheet clamping device winds the sheet on the peripheral surface of the drum. It is characterized in that it is constituted by the sheet rear end clamp device described in item 5.

[0010]

According to the above construction, the sheet can be tightly wound around the peripheral surface of the drum and the rear end portion of the sheet can be easily and surely clamped according to the length of the sheet.

[0011]

The present invention will be described in detail below with reference to examples.

FIG. 1 is a perspective view of a first embodiment of a sheet trailing edge clamp device, and FIG. 2 is a sectional view taken along the line AA of the side surface of FIG. 1 and the sheet trailing edge clamp member 3. 2, 3, 4, 5, 6, and 7 are side views showing a series of operations in this embodiment.

In FIG. 1, the drum 1 is rotatably supported by left and right side frames (not shown) installed outside both side surfaces via a drum shaft 1a to which the drum 1 is attached, and is driven by an unillustrated driving device to form an arrow. It is mounted so that it can rotate in any direction.

As shown in FIG. 2, a sheet front end clamp member 2 is mounted on the peripheral surface of the drum 1 so as to provide a space 2a with the peripheral surface of the drum 1, and is fed in the direction of arrow E. It is installed movably in the arrow direction by a driving device (not shown) so as to sandwich the front end of the formed sheet 6 on the peripheral surface of the drum 1.

A sheet rear end clamp member 3 (hereinafter referred to as a clamp member 3) is rotatably supported on both side drum shafts 1a, and a sheet is provided near the drum 1 peripheral surface of the clamp member 3. An ironing member 3a and a clutch claw 3b are provided. On both sides of the clamp member 3, there are cams 4
Is fixedly provided, and the clamp member 3 is guided by the elongated hole 4b at the center of the cam 4 so as to be movable in the axial direction. The reaction force of the spring 5 causes the clamp member 3 to always move toward the shaft of the drum 1. It is biased toward the heart.

A clamp member control mechanism 10 is installed as a mechanism for controlling the clamp member 3. As the configuration of the clamp member control mechanism 10, the positioning plate 11 is mounted so as to be movable in the vertical direction by the guide of the shaft 12 fixedly mounted on the switch fixing plate 14, and is always moved upward by the tension of the spring 13. It is urged by arrow a). The end surface 11a of the positioning plate and the notch 4a of the cam 4 are in contact with each other, and are installed so that the clamp member 3 does not rotate due to the frictional force generated at both end surfaces. Switch 16
Are fixed on the switch fixing plate 14. Further, the solenoid 19 is fixed on the solenoid fixing plate 17, the solenoid shaft 19b is fixed to the switch fixing plate 14 via the shaft 19a, and the energization of the solenoid 19 turns the switch fixing plate 14 on and off. The guide of the shaft 15 fixedly mounted on the fixed plate 17 is movable in the vertical direction (arrow B). Solenoid fixing plate 17
Is a shaft 1 fixed on a side frame (not shown).
The guide 8 is mounted so as to be movable in the vertical direction (arrow C) by a drive device (not shown).

The clamp member control mechanism 10 has a symmetrical shape on both sides with respect to the center of the drum 1 and performs the same movement (the mechanism portion on the right side surface is not shown).

Next, a series of clamping operations for winding the sheet around the drum peripheral surface will be described.

In FIG. 2, the leading end of the sheet 6 sent in the direction of arrow E by a sheet feeding mechanism (not shown) is a space between the sheet leading end clamp member 2 and the circumferential surface of the drum 1 on the circumferential surface of the drum 1 which is not rotating. The sheet leading end clamp member 2 is moved in the arrow direction by a driving device (not shown) when the sheet 6 is fed to the peripheral surface of the drum 1. Next, in FIG. 3, when the drum 1 rotates in the direction of the arrow and the sheet front end clamp member 2 moves to the left outside of the clamp member 3, the drive circuit (not shown) turns on the solenoid 19 to turn on the solenoid shaft 19b. Suction is performed, and in conjunction with this, the switch fixing plate 14 and the positioning plate 11 move in the arrow G direction by a predetermined amount. Further, the clamp member 3 is moved in the direction of the arrow by the reaction force of the spring 5, and the sheet ironing member 3a and the clutch claw 3b on the clamp member 3 are wound around the peripheral surface of the drum 1 to form the sheet 6.
Stops when is pressed. The cutout portion 4a of the cam 4 and the end surface 11a of the positioning plate 11 are still in contact with each other,
The clamp member 3 is held stationary with respect to the drum 1 by the frictional force generated by the tension of the springs 5 and 13.

Next, in FIG. 4, the drum 1 rotates while the ironing member 3a on the clamp member 3 and the clutch claw 3 press the sheet 6 on the drum 1, and as shown in FIG. The rear end 6a comes off the clutch claw 3b,
When the clutch pawl 3b and the peripheral surface of the drum 1 come into contact with each other, a frictional force is generated between the clutch pawl 3b and the peripheral surface of the drum 1.

Here, the frictional force generated on the contact surface between the notch 4a of the cam 4 and the end surface 11a of the positioning plate 11 is F
1, the frictional force between the clutch claw 3b and the peripheral surface of the drum 1 is F2,
Clutch claw 3b, seat ironing member 3a, and seat 6
When the frictional force F3 is set to F2>F1> F3, the clutch claw 3b and the sheet squeezing member 3a are in contact with the sheet 6 (see FIG. 4).
In the state (1), since the relationship of the frictional force is F1> F3, the drum 1 rotates, but the clamp member 3 is stationary due to the frictional force F1. When the clutch pawl 3b is disengaged from the seat rear end 6a and abuts on the peripheral surface of the drum 1, the frictional force relationship becomes F2> F1.
The clamp member 3 starts to rotate simultaneously with the drum 1 by 2 (state of FIG. 5). Then, in FIG. 6, when the clamp member 3 rotates at the same time as the drum 1, the notch 1 notch portion 4a of the cam 4 rotates to push the end surface 11a of the positioning plate 11 downward. As the positioning plate 11 moves, the other end 11b of the positioning plate 11 contacts the switch 16 and turns on the switch 16. By the ON signal of the switch 16, the solenoid fixing plate 17 is driven by a driving device (not shown).
Move in the direction of the arrow.

That is, as shown in FIG. 7, the clamp member control mechanism 10 moves downward, the engagement between the outer peripheral surface of the cam 4 and the positioning plate 11 is released, and the operation of winding the sheet 6 around the peripheral surface of the drum 1 is completed. . In this series of sheet winding operations, the sheet squeezing member 3a is in contact with the sheet 6 while being pressed from the front end to the rear end of the sheet 6, so that no slack occurs. After the wrapping operation is completed,
Since the contact between the clamp member 3 and the clamp member control mechanism 10 is completely separated, the drum 1 can be smoothly rotated and does not hinder the subsequent image forming work or printing work.

The operation of contact between the seat ironing member 3a and the clutch pawl 3b and the seat 6 will now be described in detail.

In the state in which the drum 1 is rotated and the clamp member 3 is stationary to press the sheet 6 in FIG. 4, the sheet ironing member 3a and the clutch claw 3b are in contact with the sheet 6 at the same time. Seat 6 is clutch claw 3 like
When disengaged from b, it is necessary that the clutch claw 3b surely contacts the drum 1 and the clamp member 3 be rotated simultaneously with the drum 1 by the frictional force.

In this case, as shown in FIG. 10, the clutch claw 3b made of an elastic member biased in the circumferential direction of the drum 1 or the sheet ironing made of an elastic member biased in the circumferential direction of the drum 1 as shown in FIG. The above object can be achieved if either one of the members 3a is an elastic member. That is,
If one of them is formed of an elastic member that is urged in the circumferential direction of the drum, when the seat 6 is disengaged from the clutch claw 3b while pressing the seat 6 by the reaction force of the spring 5 or its own elastic force. The clutch claw 3b can surely contact the drum 1.

Since the frictional force F2 when the clutch claw 3b and the drum 1 are in contact with each other is preferably sufficiently larger than F1 or F3, the surface shape of the drum 1 at the contacting portion is as follows.
The surface may be rough to increase the friction coefficient, or may be formed of an elastic body having a high friction coefficient.

FIG. 8 shows another embodiment of the sheet ironing member 3a.

A roller 7 parallel to the drum shaft 1a is rotatably supported at the tip of the sheet ironing member 3a.
The sheet 6 rotates while pressing the sheet 6 as the drum 1 rotates.

Since the contact portion with the sheet 6 makes a rotary contact, there is an effect that the slack of the sheet 6 is removed without damaging the surface of the sheet.

FIG. 9 shows another embodiment of the peripheral surface shape of the drum 1.

An uneven groove 1b is formed on at least the peripheral surface of the drum 1 which is in contact with the clutch pawl 3b. When the clutch pawl 3b is separated from the seat rear end 6a and abuts on the peripheral surface of the drum 1, the clutch pawl is formed. The tip of 3b engages with the groove 1b of the drum 1, the clamp member 3 is securely locked to the drum 1, and the rear end of the sheet 6 is clamped.
And the drum 1 can be rotated simultaneously.

The sheet ironing member 3a and the clutch claw 3b are members for pressing the sheet 6 or abutting on the drum 1. One or a plurality of abutting surfaces extending in the direction of the drum shaft 1a are installed. I'm good.

FIG. 12 is a side view showing an embodiment of an ink jet recording apparatus equipped with the mechanism according to the present invention. The configuration and operation will be described.

The main components of this apparatus are a recording head 105 that selectively ejects ink droplets to form an ink image on a sheet, and a drum 1 that faces the recording head 105 with a gap. , A paper feed cassette 10 located upstream (on the right side) of the recording head 105 for feeding the sheet 6
1 and a paper feed mechanism 102, and a paper discharge mechanism 103 and a paper discharge cassette 104 located downstream of the drum 1 for discharging the sheet 6 after image formation.

First, in the paper feeding process, the paper feeding cassette 10
The sheet 6 in 1 is fed to the vicinity of the drum 1 by the sheet feeding mechanism 102. Here, the tip of the sheet 6 is clamped by the clamp member 2 on the peripheral surface of the drum 1. The drum 1 is rotated in the direction of the arrow by driving a motor (not shown), and is wound around the drum 1 peripheral surface by the action of the clamp member 3 and the clamp member control mechanism 10.

Further, in the recording process for forming an image, the recording head 105 is synchronized with the constant speed rotation of the drum 1.
Writes an ink image for one page on the drum 1 while moving a predetermined amount in a direction parallel to the axis of the drum 1.

Ink is supplied to the recording head 105 from the ink supply unit 106.

In the paper discharge process, the sheet 6 after the image formation
Is separated from the peripheral surface of the drum 1 by a device (not shown), and is discharged to the discharge cassette 104 by the discharge mechanism 103.

Here, a detailed description of the operation of clamping the leading end and the trailing end of the sheet 6 is omitted because it is the same as in the first embodiment.

[0040]

According to the present invention, the sheet ironing member 3a
The sheet 6 is pressed and continuously squeezed and wound around the drum 1 circumferential surface, and the clamp claw 3b comes off the rear end of the sheet 6 and contacts the drum 1, and at the same time clamps the rear end of the sheet, so that the sheet is wound without slack. He is surely clamped. Further, when the rear end of the sheet is clamped, it is not necessary to previously input the information on the sheet length, and a complicated device of a detection mechanism and a transmission mechanism is not required at all electrically or mechanically. For this reason, if the sheet has a predetermined length range,
Corresponding to almost stepless sheet length, it can be securely clamped.

Further, since the clamp member 3 mounted on the drum 1 has a small number of parts and can be made small and lightweight, the weight balance of the drum 1 is good and uneven rotation and vibration can be reduced. It is possible to obtain high speed rotation at a constant speed, and it is possible to shorten the image forming time.

Further, in the ink jet recording apparatus equipped with the present invention, the sheet can be wound and clamped on the peripheral surface of the drum without slack, and the slack of the sheet and the deterioration of the image quality due to peeling, stains, jamming and the like are harmful. Can be removed.

Although the rotation of the drum at the time of printing is sped up, the vibration and uneven rotation of the drum can be reduced and the resulting image distortion can be suppressed, so that a high quality image can be obtained and the image forming time can be shortened.

Further, since the sheet feeding cassette 101 and the sheet feeding mechanism section 102 and the sheet trailing end clamp member 3 can cope with the sheet length without any mechanical interlocking, the complicated mechanism can be removed and the reliability can be improved. High equipment is possible. Therefore, it is possible to provide a small-sized and inexpensive inkjet recording device.

[Brief description of drawings]

FIG. 1 is a perspective view of a seat trailing end clamp device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a side surface of the first embodiment of the present invention.

FIG. 3 is a diagram showing an operation of the first exemplary embodiment of the present invention.

FIG. 4 is a diagram showing an operation of the first exemplary embodiment of the present invention.

FIG. 5 is a diagram showing an operation of the first exemplary embodiment of the present invention.

FIG. 6 is a diagram showing an operation of the first exemplary embodiment of the present invention.

FIG. 7 is a diagram showing an operation of the first exemplary embodiment of the present invention.

FIG. 8 is a side view showing another embodiment of the present invention.

FIG. 9 is a side view showing another embodiment of the present invention.

FIG. 10 is a side view showing another embodiment of the present invention.

FIG. 11 is a side view showing another embodiment of the present invention.

FIG. 12 is a side view showing another embodiment of the present invention.

[Explanation of symbols]

 1: Drum 2: Sheet front end clamping member 3: Sheet rear end clamping member (clamping member) 3a: Sheet ironing member 3b: Clutch claw 6: Sheet 10: Clamping member control mechanism 100: Inkjet recording device 101: Paper feeding mechanism unit 103 : Paper ejection mechanism section 105: Recording head 106: Ink supply section

Claims (6)

[Claims] 1. A sheet trailing end clamp device for a sheet wound around a drum, comprising: a drum having a leading end clamp member for holding a leading end of the sheet on a drum peripheral surface; and a drum surface rotatably supported near a drum surface. A sheet rear end clamp member disposed on the sheet rear end clamp member, and a sheet ironing member for pressing the sheet on the drum peripheral surface on the sheet rear end clamp member, and the drum and the sheet rear end when contacting the drum surface. A seat trailing end clamp device, comprising: a clutch pawl installed so that the clamp member is simultaneously rotated. 2. The seat trailing end clamp device according to claim 1, wherein the clutch claw is made of an elastic member biased in the circumferential direction of the drum. 3. The sheet trailing edge clamp device according to claim 1, wherein the sheet squeezing member is made of an elastic member urged in the circumferential direction of the drum. 4. The sheet trailing edge clamp device according to claim 1, wherein a contact portion of the sheet squeezing member with the sheet is a rotating roller. 5. The seat trailing end clamp device according to claim 1, wherein a plurality of grooves that engage with the clutch claws are provided on the peripheral surface of the drum. 6. In an ink jet recording apparatus for ejecting ink droplets to obtain an image, a recording head that selectively ejects ink droplets to form an ink image on a sheet faces a recording head with a gap. A sheet clamp device having a drum, a sheet feeding member for feeding a sheet, and a sheet discharging member for discharging a printed sheet, wherein the sheet clamping device winds the sheet on the peripheral surface of the drum. 5. An inkjet recording apparatus comprising the sheet trailing edge clamp device according to item 5.