JPH08337021A - Sheet feeding device - Google Patents

Abstract

PURPOSE: To prevent transmision of abnormal torque on occasion of sheet jamming or the like by a method wherein a torque limiter is provided at a power transmission part transmitting torque of a motor in a sheet feeding device that feeds recording sheets at a specified speed. CONSTITUTION: In a sublimation thermal transfer recording apparatus, a thermal head 3 is pressed against a platen roller 4, and ink on an ink sheet 2 is sublimated with heating elements on the thermal head 3 heated in accordance with data, and transferred onto a recording sheet. After the transfer, the recording sheet 1 is fed at a specified amount of feeding by rotation of the platen roller 4 driven by a sheet feeding mechanism composed of a motor 6 and a gear train. A torque limiter is incorporated in a gear 8 in the gear train of the sheet feeding mechanism. The torque limiter is composed of a limiter yoke, a magnet and a stator yoke, and constructed so that it can run idle when abnormal torque occurs to the sheet feeding mechanism. Thereby, transmission of abnormal torque can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeding device for carrying recording paper such as a printer.

[0002]

2. Description of the Related Art Conventionally, a paper feeding device such as a thermal transfer recording device having a heavy paper feeding load has been disclosed in Japan Society of Mechanical Engineers No. 70.
It is described in No. 930-9 Study on Ink Sheet Conveying of Thermal Transfer Printer in the Proceedings of the Annual General Meeting.

[0003]

In the prior art, the protection of the paper feeding device is not taken into consideration, and a strong force is generated in the paper driving unit because the motor of the driving source is interposed through the speed reducing mechanism. When a paper jam occurs, the recording paper will be altered, deformed, or shaken, and it will be necessary to strengthen the device so that it will not be affected by the high load and high pulling force of the paper feed, resulting in higher component costs. .

Further, in the worst case, there is a problem that an abnormal force is applied to the paper feeding mechanism, the driving mechanism is destroyed and the apparatus becomes unusable.

An object of the present invention is to provide a paper feeding device which can realize highly accurate and highly reliable paper feeding.

[0006]

The above object is achieved by incorporating a torque limiter which does not transmit torque when an abnormal torque is generated in the paper feed drive mechanism.

The torque limiter incorporated in the paper feed drive mechanism utilizes the magnetic force of the magnet in the direction of the attractive force to utilize the frictional force between the magnet and the ferromagnetic material due to the attractive force.

Further, in order to increase the frictional force, it is achieved by the structure in which the magnet and the ferromagnetic material are in direct contact with each other.

[0009]

[Function] The paper feeding section is not broken even when an abnormality such as a paper jam occurs. Moreover, stable operation is possible without deterioration over time.

[0010]

Embodiments of the present invention will be described below with reference to FIGS. In addition, in this embodiment, among the paper feeding devices,
It shows a case of a sublimation type thermal transfer recording type paper feeding device using thermal transfer, which has a large paper feeding load.

FIG. 2 is a perspective view of a sublimation type thermal transfer recording apparatus using the paper feeding apparatus according to the present invention. 1 is a recording paper, 2 is an ink sheet, 3 is a thermal head, 4 is a platen roller, 5 is an ink sheet take-up roller, 6 is a motor, 7 is a worm, and 8 to 10 are gears.

The operation of the sublimation type thermal transfer recording apparatus thus constructed will be described below. In the sublimation type thermal transfer recording apparatus, the thermal head 3 presses the recording paper 1 via the ink sheet 2 against the platen roller 4, causing the heating element of the thermal head 3 to generate heat according to the data and sublimate the ink in the ink sheet 2. Then, the recording paper 1 is transferred.
After the transfer, the recording paper 1 is sandwiched between the platen roller 4 and the thermal head 3 which are rotated by obtaining a driving force by the paper feed driving means composed of the motor 6 and the gear train, and fed by a predetermined amount.

Next, the paper feed load will be considered with reference to FIG. FIG. 3 is an explanatory diagram of the paper feeding device 1 in this embodiment. The thermal head 3 is pressed against the platen roller 4 with a high load by the head pressing spring 11. A load due to elastic deformation of the platen roller 4, a load due to friction with the ink sheet 2, and the like are generated on the platen roller 4 to which an elastic body such as rubber is attached as a feeding load of the recording paper 1.

In order to improve the image quality of the sublimation type thermal transfer recording apparatus, it is necessary to convey the recording paper 1 with high precision in order to superimpose each color of yellow, magenta and cyan with high precision for additive color mixing. Further, depending on the printing conditions, the heating position of the ink sheet 2 by the thermal head 3 changes, so that the friction coefficient of the recording paper 1 in contact with the ink sheet 2 partially changes, so that the change in the friction coefficient changes. It is necessary to prevent unevenness, and in order to properly feed the paper, the reduction ratio is set large and the driving force for paper feeding is increased.

The worm gear 7 is decelerated from gear 8, gear 9, and gear 10. As a result, the driving force of the recording paper 1 easily exceeds 10 kg. The driving force required for the normal operation of the recording paper 1 is 1 Kg, and there is a sufficient margin for torque fluctuation, and stable paper feeding can be performed. However, when the recording paper 1 is inserted at an angle, or when a large amount of paper is fed due to a malfunction of the automatic paper feeding mechanism, a paper jam occurs and abnormal force is exerted, and the driving force required for paper feeding is generated. Is over 10 kg, the recording sheet 1 cannot be driven, and if there is no protection mechanism, the A portion of the gear 8 to which the greatest force is applied is chipped. A worm gear 7 that may have a small required torque is suitable as a protection mechanism for inserting the torque limiter. However, when the worm gear 7 has a large reduction ratio and a torque limiter is incorporated, a large variation in driving force occurs due to a slight torque fluctuation. Therefore, a torque limiter is incorporated in the gear 8.

FIG. 1 is an explanatory view of a torque limiter built in the gear 8. The gear 8 includes a gear 12, a gear 13, a limiter yoke 14, a magnet 15 and a stator yoke 16. The stator yoke 16 and the magnet 15 are fixed to the gear 12, and the limiter yoke 1 is fixed to the gear 13.
4 is fixed. The gear 12 and the gear 13 are mounted in contact with the limiter yoke 14 and the magnet 15 so that the limiter yoke 14 and the magnet 15 are coaxially rotatable.

The magnet 15 attached to the gear 12
And a ferromagnetic limiter yoke 1 attached to the gear 13.
Since the magnets 4 are in contact with each other, the magnetic resistance of the magnet 15 can be reduced. Since the magnetic resistance is reduced and the magnetic force can be effectively used, the attractive force is increased and the frictional force can be increased.

Further, since the force for generating the frictional force acts only as an attractive force between the magnet 15 and the limiter yoke 14, the pressure as the attractive force for obtaining the frictional force does not act on anything other than the friction surface. Therefore, unnecessary power does not work.

With this configuration, even if a paper jam occurs and an abnormal torque occurs in the paper feeding mechanism, the torque limiter operates and the abnormal torque is not transmitted. Therefore, the paper feed drive member is protected. Further, although the present embodiment is built into the thermal transfer recording apparatus, it can be used in other places where small size and high torque transmission are required.

In FIG. 4, a magnet 17 is fixed to the limiter yoke 14 of FIG. 1, and the magnet 15 and the magnet 17 are arranged so as to face each other with different polarities. By arranging the magnets 15 and 17 to face each other with different polarities, the magnetic force is increased and the rotational torque transmission force is increased.

Further, as shown in FIGS. 1 and 4, the surfaces of the magnets 15 and 17 opposite to the torque transmission surfaces are made of a ferromagnetic stator yoke 16 and a limiter yoke 14.
By arranging, the magnetic force can be increased and the torque transmission force can be increased.

In FIG. 5, a recess 18 is provided on the torque transmitting sliding surface of the torque limiter 8. When dust is inserted into the sliding surface at the time of assembly or when the sliding surface is scraped due to sliding and scraps occur, the friction coefficient of the sliding surface becomes small and the torque transmission force changes. Recess 1 provided on the torque transmission sliding surface
8, dust and shavings accumulate, and a stable torque transmission force can always be obtained.

FIG. 6 shows a rubber sheet 19 of a high friction member arranged to increase the friction coefficient of the torque transmission sliding surface. Since the rubber sheet 19 has a large friction coefficient, the transmission torque can be increased.

FIG. 7 shows the magnet 15 and the magnet 1.
7, a plurality of magnetic poles are arranged on the torque transmission sliding surface. By disposing a plurality of magnetic poles, the magnetic flux is not partially concentrated on the limiter yoke 14 or the stator yoke 16. Therefore, the thickness of the limiter yoke 14 or the stator yoke 16 can be reduced.

[0025]

According to the present invention, the paper feed mechanism can be protected even when an abnormal paper feed occurs.

[Brief description of drawings]

FIG. 1 is a sectional view of a torque limiter according to the present invention.

FIG. 2 is a perspective view of a paper feeding device according to the present embodiment.

FIG. 3 is an explanatory diagram of a drive unit of the paper feeding device according to the present embodiment.

FIG. 4 is another sectional view of the torque limiter according to the present invention.

FIG. 5 is an explanatory view of an embodiment in which a concave portion is provided on the torque transmission sliding surface according to the present invention.

FIG. 6 is an explanatory diagram of an embodiment in which a high friction member is arranged on the torque transmission sliding surface according to the present invention.

FIG. 7 is a perspective view when a plurality of magnetic poles are arranged on the torque transmission sliding surface of the magnet of the paper feeding device according to the present invention.

[Explanation of symbols]

 12 ... Gear, 13 ... Gear, 14 ... Limiter yoke, 15 ... Magnet, 16 ... Stator yoke.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuo Otsuka 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Stock company, Hitachi, Ltd. multimedia system development headquarters (72) Inventor Masami Takada 1410 Inada, Hitachinaka-shi, Ibaraki Company Hitachi, Ltd. Personal Media Equipment Division (72) Inventor Naohiro Ozawa 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Stock Company Hitachi Ltd. Multimedia System Development Division

Claims (7)

[Claims] 1. A paper feed comprising a motor as a power source for feeding the recording paper at a predetermined speed, a means for narrowing the recording paper so as to be movable, and a power transmission member for transmitting the rotational force of the motor. In the apparatus, the power transmission section includes a torque limiter, and the paper feeding apparatus. 2. The torque limiter according to claim 1, wherein the first rotation member is rotatable about a rotation shaft, the second rotation member is rotatable about the rotation shaft, and the first rotation member is rotatable about the rotation shaft. Of the rotating member and an interlocking member for interlocking the second rotating member, wherein the interlocking member has a magnet mounted on the first rotating member, and a ferromagnetic material mounted on the second rotating member. And a torque limiter that works by contacting the above ferromagnetic material. 3. The torque limiter according to claim 1, wherein the first rotary member is rotatable about the rotary shaft, the second rotary member is rotatable about the rotary shaft, and the first rotary member is rotatable about the rotary shaft. It comprises an interlocking member that interlocks one rotating member and the second rotating member, wherein the interlocking member has a magnet mounted on the first rotating member and a magnet mounted on the second rotating member.
A protection mechanism for the paper feeding device that interlocks by contacting the different poles of the magnet and the magnet. 4. The torque limiter according to claim 2 or 3, wherein the magnet is mounted on a rotating member via a ferromagnetic material. 5. A torque limiter according to claim 2, 3 or 4, wherein a radial recess is provided on one or both of the torque transmission contact surfaces of said interlocking member. 6. A torque limiter according to claim 2, 3 or 4, wherein a friction member is provided on a torque transmission contact surface of said interlocking member. 7. The torque limiter according to claim 2, 3 or 4, wherein a plurality of magnetic poles are provided on a contact surface of the connecting member on the magnet side.