JP3274925B2 - Roll paper end detection device - 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 feeder for feeding a roll paper used in an image forming apparatus such as a copying machine or a printer to an image forming section. The present invention relates to a paper end detection device.

[0002]

2. Description of the Related Art As means for feeding roll paper to an image forming section, there is known a roller means comprising a feed roller having a driving means and a driven roller which abuts on the feed roller via a paper and is driven by friction. The roll paper drawn out between these rollers is sent to the image forming section with the leading end side of the roll paper interposed therebetween. These rollers are provided with shaft holes on both side plates of the apparatus main body so as to be parallel to the width direction of the roll paper, and are rotatably supported via bearings. Similarly to the feed roller, the rotating shaft of the driven roller is supported by both side plates of the apparatus body, and an encoder that detects the end of the roll paper is fixed to the shaft end protruding outward from the side plate. The end of the roll paper is detected by monitoring the presence / absence of rotation of the encoder at the time of paper feeding by a sensor arranged opposite to the encoder.

[0003]

In the above-described apparatus, particularly when handling a wide and large-sized roll paper of A2 or larger, the rotation used as the shaft of the feed roller and the driven roller may occur due to design or strength problems. It is necessary to increase the diameter of the shaft so as not to bend by its own weight. Also,
The encoder is fixed to the center of the rotating shaft of the driven roller at one end protruding outside the side plate of the apparatus main body, which is an obstacle to miniaturization and cost reduction of the apparatus. further,
In the assembling work, two rotating shafts of a feed roller and a driven roller must be simultaneously incorporated into both side surfaces, which complicates the assembling work.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to provide a roll paper end detecting device which is easy to design and assemble and can be reduced in cost.

[0005]

In order to solve the above-mentioned problem, a roll paper whose end is fixed to a winding core is pressed against a feed roller driven at the time of feeding paper and the surface of the feed roller via paper. in friction transfer delivery by a driven roller which is driven by the roll paper end detection device for detecting the exhaustion of the paper roll by detecting the presence or absence of rotation of the driven roller and,
The driven roller is supported by a member different from the both side plates in a space between both side plates supporting the axis of the feed roller.
And a short- axis short-length roller ,
An encoder is provided in a space between both side plates so as to be driven by the rotation of the driven roller, and consumption of the roll paper is detected based on a signal from the encoder.

[0006]

In such a configuration, the driven roller rotatably arranged in the space between both side plates sandwiches the roll paper and feeds out the sheet according to the rotation of the feed roller. When the roll paper is consumed and finished, the roll paper stops because the end of the roll paper is fixed to the core, and the feed roller slides on the roll paper. The rotation of the driven roller is stopped by the stop of the roll paper, and the encoder that has been rotating in contact with the driven roller also stops. As described above, when the paper is fed, that is, when the encoder stops even though the feed roller is rotating, the signal is detected to notify the end of the roll paper.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a side sectional view showing a state in which a roll paper end detecting device according to the present invention is incorporated in an image forming apparatus main body. Reference numeral 1 denotes a roll paper as a transfer material. A detachable holder (not shown) is inserted into a cylindrical core member 2 around which the roll paper 1 is wound, and the holder is supported by an appropriate mounting portion. As a result, the roll paper is rotatably loaded inside the image forming apparatus. A roll paper 1 whose end is fixed to a winding core 2 by an adhesive or the like;
Although it is classified into two types, that is, one that is not fixed, the present invention is suitably used for one in which the end of the roll paper 1 is adhered to the core 2.

A roll paper end detecting device 3 is disposed above a position where the roll paper 1 is loaded. A feed roller 5 for rotating the roll paper end detection device 3 based on a paper feed signal and feeding the roll paper 1 to the image forming unit 4;
A driven roller 6 which comes into pressure contact with the feed roller via the drawn-out roll paper and is driven by frictional force;
Encoder 7 that rotates by following a driven roller in contact with the surface of the sensor, and sensor 8 that detects a signal from encoder 7
And guide plates 10 and 11 for guiding the roll paper 1 wound around the core 2 to the cutter 9. Feed roller 5
And the driven roller 6 includes a rotating shaft 12 such as a metal shaft,
13 and elastic rollers 14 and 15 made of rubber, synthetic resin, or the like having relatively high frictional resistance and fixed to substantially the center of the rotating shafts 12 and 13 in the axial direction. The elastic rollers 14 and 15
The roll paper passing therethrough is formed in a cylindrical shape or a barrel shape so as not to be wrinkled, and the roll paper 1 is sent out by being brought into contact with an appropriate pressure. Further, these rollers may be short-length rollers so as to be in contact with a part of the center of the roll paper width. The feed roller 5 has both ends of the rotating shaft 12 rotatably supported by bearings 36, 37 and the like on both side plates 35 of the apparatus main body. An external drive source is connected to one end of the feed roller 5 by a gear, a belt, or the like to synchronize with the rotation speed of the photoconductor 20. Driven roller 6
Are arranged in the space between both side plates 35,
A rotation shaft 13 smaller than the rotation shaft 12 of the feed roller 5 is rotatably supported by a blanket (not shown) provided on the guide plate 10 via bearings 38 and 39, and the elastic roller 15 is an elastic roller 14 of the feed roller 5. In contact with the surface. The guide plates 10, 11 are provided with elastic rollers 14,
A hole is formed so as not to obstruct the contact of the driven roller 15 with the guide plate 10, and the surface used for the opening is bent perpendicularly to the surface of the guide plate 10 so that the rotation shaft 13 of the driven roller 6 and the rotation shaft of the encoder 7 are formed. Also serves as a rotatable side plate. As the sensor 8, a sensor utilizing an optical sensor such as a photo interrupter sensor is preferably used.

FIG. 2 is a diagram showing an example of an embodiment of a roll paper end detecting device according to the present invention, and FIG. 3 is a diagram showing a conventional example. In the conventional example of FIG.
Must be arranged longer than the width of the roll paper in order to be mounted between the both side plates 35, and it is necessary to increase the strength of the rotating shafts 12 and 13 to some extent such as the bending thereof. Further, since the encoder 7 and the sensor 8 are disposed outside the apparatus side plate 35, it is necessary to further widen a decorative plate that covers them. In the embodiment of FIG. 2 as compared with the conventional example, the thickness of the rotating shaft can be made thinner by shortening the length of the rotating shaft 13 of the driven roller 6. Further, by arranging the encoder 7, the sensor 8, and the like inside the device, the size can be reduced.

Next, the operation will be described with reference to FIG. 1. As is well known, the surface of the photoconductor 20 rotating in the direction of arrow A is corona-charged by the corona discharger 21 in the image forming section 4 as is well known. Next, an electrostatic latent image is formed on the photoconductor 20 by projecting a light image from the document image projection device 22. The latent image on the surface of the photoconductor 20 is visualized by toner in the developing unit 23 and sent to a transfer unit. On the other hand, the leading end of the roll paper 1 is sent to the transfer unit of the image forming unit 4 by the feed roller 5 and the driven roller 6. Next, the roll paper 1 cut into a desired size by the cutter 9 transfers the toner image on the photoconductor 20 by the transfer corona discharger 26 and the peeling corona discharger 27. After that, the roll paper 1
The sheet is conveyed to the fixing device 28, is formed into a permanent image, and is discharged out of the apparatus. The surface of the photoreceptor 20 after the transfer is cleaned by a cleaner 29 and is gradually charged by an eraser lamp 30 to be prepared for the next image formation.

When the roll paper 1 is consumed by image formation and reaches the end, the roll paper is stopped on the core 2 despite the rotation of the feed roller 5 and stops.
At this time, the feed roller 5 rotates by causing a slip with respect to the roll paper 1, but the driven roller 6 does not rotate because the roll paper 1 stops. With the stop of the driven roller 6, the encoder 7 in contact with the surface of the elastic roller 15 stops, and this signal is detected by the sensor 8 to notify the operator that the roll paper 1 needs to be replaced. The present invention is preferably used for a roll paper in which the roll paper 1 is fixed to the core 2, but in order to prevent a malfunction when the roll paper 1 is not fixed to the core 2, FIG. Photo sensor 3 shown
1 may be arranged. The photo sensor 31 includes a sensor light transmitting unit and a light receiving unit. The roll paper blocks the sensor light of the photo sensor, and the light receiving unit of the photo sensor 31 detects the end of the roll paper when the roll paper is exhausted. To inform. By using these methods in combination, it is possible to detect the end of the roll paper in either the roll paper whose end is fixed to the core or the roll paper not fixed to the core.

[0012]

According to the roll paper end detecting device of the present invention, by shortening the rotating shaft of the driven roller, the thickness of the rotating shaft can be reduced without sagging. As a result, a roll paper end detecting device that can be manufactured at low cost and that can be easily assembled by downsizing components can be provided.

[0013]

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an embodiment according to the present invention.

FIG. 2 is a plan view showing an embodiment according to the present invention.

FIG. 3 is a plan view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Roll paper 2 Core 5 Feed roller 6 Follower roller 7 Encoder 8 Photo interrupter

Claims (1)

(57) [Claims] 1. A feed roller driven at the time of feeding a roll paper whose end is fixed to a winding core, and a driven roller pressed against the surface of the feed roller via paper and driven by frictional transmission with the paper. delivery, the roll paper end detection device for detecting a depleted roll paper detecting the presence or absence of rotation of the driven roller, the driven roller, and the two side plates in the space between both side plates that support the shaft of the feed roller Is due to another member
Ri is supported will be, and consists roller minor axis of short length,
Further comprising an encoder provided in the space between the both side plates so as to be driven by the rotation of the driven roller, and detecting the consumption of the roll paper based on a signal from the encoder. apparatus.