JPS60128856A - Driving device - Google Patents

Abstract

PURPOSE:To reduce a rotary load to be driven rotatably by a pulse motor by forming the attracting of repelling surface of a stator on a portion opposed to the surface to be attracted or repelled of a rotor. CONSTITUTION:When a relative rotary force is generated between a rotor 12 and a stator 13 so that the rotor 12 and a platen 1 rotate, an attracting force due to the magnetic force between the stator 13 and the rotor 12 acts in a direction of the rotational shaft 1a of the platen 1 but does not act in the radial direction of the rotor 12. Accordingly, a radial load due to the magnetic force is not applied to a bearing 9. The magnetic forces acted in the directions of arrow C and C' are equal to each other to cancel each other. Thus, the load of the direction of the shaft 1a is not applied to the bearing 9. Therefore, even if a structure that the stator 13 and the rotor 12 are not coated is formed, the rotary load of the platen 1 does not increase.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a direct drive drive device using a pulse motor.

[Prior Art] A conventional drive device using a pulse motor will be briefly described using a paper feeding device such as a typewriter as an example.

FIG. 1 shows an example of a paper feeding device using a conventional power transmission means such as a gear. In FIG. 1, 1 is a platen, and a gear 2 is fixed to one end of a rotating shaft 1a of the platen. This gear 2 is engaged with a pinion gear 5 fixed to the output shaft of a pulse motor 4 via an idler gear 3, and rotation of the pulse motor 4 is transmitted thereto. In addition, the pulse motor 4
is connected to a drive circuit (not shown) on the frame side by a lead wire 4a with a connector. Further, a pinch roller 7 and a pail roller 8 are in contact with the outer circumferential portion of the platen l, and the rotation of the pulse motor 4 allows the paper 6 to be moved in the vertical direction with respect to printing means (not shown). or,
The platen 1 is fixed to the frame by a ratchet (not shown) via a platen bearing 9.9', and can be removed in the direction of arrow A by releasing the ratchet.

However, in the conventional paper feeding device as described above, gear 2,
Idler gear 3. Since a power transmission means such as a pinion gear 5 is used, it is expensive, and has the drawbacks of high noise and lack of reliability.

FIG. 2 shows a conventional example of a paper feeding device that employs a direct drive system. In the figure, parts given the same reference numerals as those in FIG. 1 indicate the same configuration.

The paper feeding device shown in FIG. 2 has a configuration in which the output shaft of a pulse motor 10 is integrally connected to the rotating shaft 1a of the platen 1. Therefore, since this paper feeding device does not use a power transmission unit such as a gear, it has higher precision and
It provides high reliability and is inexpensive. However, the rotor 10a of the motor is fixed to the stator 10b fixed to the frame.
Since the platen 1 is covered with (not shown) and then the platen 1, which was a very complicated task. This poses a burden on the user since the platen has to be attached and detached relatively frequently for cleaning, paper jams, etc.

Therefore, the applicant of the present application proposed a device shown in FIG. 3 as a device to solve the above-mentioned problems. This paper feeding device is of the die reflex drive type similar to the device shown in Fig. 2, but the rotor j
The stator 11'b is configured as shown in the figure (with the number of phases required for driving) so as not to cover the area around the platen l, and is fixed in a position opposite to the direction in which the platen l comes off. and is connected to a lead wire 4a with a connector connected to a drive circuit (not shown).If such a configuration is adopted, the above-mentioned ratchet holding the bearing 9 of the platen l can be attached, 10 rotors just by removing
The platen 1 marked with a can be attached and detached very easily.

Now, in the device shown in FIG. 2, the attractive force due to the magnetic force generated between the rotor 10a and the stator 10b is radially distributed in the radial direction of the rotor 10a, so the bearing 9 of the platen l
bears no radial bearing load. However, the third
In the device shown in the figure, since the magnetic force acts only in the direction in which the stator tab faces, a radial bearing load is applied to the bearing 9 on the side where the stator 10b is present, and the bearing 9
Since the magnetic force acts at a location further away in the figure, the bearing 9 also receives a cantilevered radial load, increasing the rotational load on the platen l. As a result, the service life of the bearing 9 of the platen l is shortened, and the current of the stator lOb is increased due to the increased rotational load, resulting in a higher output of the pulse motor, resulting in increased heat generation and power consumption. Problems arose, and there was room for improvement.

[Purpose] The present invention has been made in view of the conventional problems as described above, and its purpose is to provide a direct drive drive device using a pulse motor, in which a rotating load of a driven object rotated by the pulse motor. The object of the present invention is to propose a drive device that can be made extremely small, has a simple structure, and can be provided at low cost.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings showing a preferred example. Here, the embodiment is a case where the drive device according to the present invention is applied to a paper feeding device such as a typewriter. Note that the parts in FIG. 1 that are given the same reference numerals as those in FIGS. 1 to 3 have the same configuration as the apparatus shown in FIGS. 1 to 3, and therefore their explanation will be omitted.

In FIGS. 4 and 5, reference numeral 12 denotes a disk-shaped rotor fixed to the rotating shaft 1a of the platen 1. As shown in FIG. This rotor 1
Unlike the conventional rotor which has a suction surface on the outer peripheral surface as shown in FIG. It is a structure consisting of. A stator 13 is fixed to a frame (not shown), and has suction surfaces 13a facing each other as shown in the diagram.
It is positioned so as to sandwich the suction surface 12a of No. 2 from both sides. Note that 13b is an excitation coil for the stator 13, and is connected to a drive circuit (not shown) via a lead wire 4a with a connector.

With the above configuration, when the excitation coil L3b is excited by the drive circuit, a relative rotational force is generated between the rotor 12 and the stator 13, and the rotor 12 and the platen I are rotated. At this time, the attractive force due to the magnetic force between the stator 13 and the rotor 12 acts in the direction of the rotating shaft 1a of the platen 1 (in the direction of arrows C and C') and does not act in the radial direction of the rotor 12, so the bearing 9 is not loaded in the radial direction by magnetic force.

Further, since the magnetic forces acting in the directions of arrow C and C' have the same magnitude and cancel each other out, no load is applied to the bearing 9 in the direction of the rotating shaft 1a. Therefore, stator 1
Even if 3 does not cover the rotor 12, the rotational load on the platen 1 does not increase as in the conventional case.In addition, in this embodiment, the platen bearing 9 is held in the frame without removing the lead wire 4a with a connector. Of course, the platen 1 can be attached and detached by simply attaching and detaching the ratchet.

Although the present invention has been described above as applied to a paper feeding device, it goes without saying that the present invention can be applied to various devices that perform direct drive using a pulse motor.

[Effects] As described above, according to the present invention, since there is no increase in the rotational load of the driven object due to magnetic force, problems such as a reduction in the life of the bearing of the driven object and an increase in heat generation and power consumption due to increased current are solved. A highly reliable drive device is obtained. Furthermore, the structure is extremely simple and can be provided at low cost.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a first example of a conventional paper feeding device. Fig. 2 is a perspective view showing a second example of a conventional paper feeding device, Fig. 3 is a perspective view showing a third example of a conventional paper feeding device, and Fig. 4 is a perspective view showing a third example of a conventional paper feeding device. A perspective view of a paper feeding device according to an embodiment. FIG. 5 is a partially enlarged view of the paper feeding device of FIG. 4 viewed from the direction of arrow B. Here, 1... platen, 1a... rotating shaft, 9...
・Bearing, 12... Rotor, 12a... Suction surface, 1
3... Stator, 13a... Attraction surface, 13b... Excitation coil. Patent applicant: Canon Co., Ltd.: Figure 5 Figure 1

Claims (1)

[Claims] In a drive device in which a drive object is directly connected to the drive shaft of the rotor of a pulse motor consisting of a rotor and a stator, an attracted surface or a repulsive surface is formed on both sides of the rotor, and the stator is The stator is formed so as to face a portion of the rotor that is half the circumference or less, and the suction surface or the repulsion surface of the stator is formed in a portion that faces the suction surface or the repulsion surface of the rotor, and A driving device characterized in that the load caused by the attraction force or the anti-light surface of the device is offset.