JPH0316113Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive mechanism for a capstan shaft of a tape recorder equipped with a so-called dual capstan mechanism.

The tape drive side, that is, the flywheel and capstan shaft on the downstream side as seen from the tape movement, are driven by a capstan drive motor or a capstan direct drive motor, and the flywheel on the drive side and the drive In other words, from the perspective of tape movement, the upstream flywheel is connected with a belt to transmit rotational force to the driven flywheel, and in tape recording and playback mode, the tape is moved by a pinch roller. A dual capstan system in which the tape is brought into pressure contact with each capstan shaft, and the tape is tensioned appropriately between the driving and driven capstan shafts to ensure proper tape running. A tape recorder having a tape running system is already known.

As shown in FIG. 1, the driven flywheel in the conventional dual-capstan type traveling system is configured to move the flywheel 2, which is integrated with the capstan shaft 1, in the axial direction by means of a compression spring 3. By pressing the capstan shaft 1, the lower end of the capstan shaft 1 is pressed against the thrust receiver 4, and an appropriate frictional force is applied. However, this conventional device has the disadvantage that the frictional force generated by the compression spring 3 is unstable, which adversely affects the rotation of the capstan shaft. Therefore, in order to stabilize the rotation of the capstan shaft, it is possible to fix a large flywheel to the capstan shaft, but if the flywheel on the driven side is made large and the inertia force is increased, the flywheel will be connected to each other by a belt. However, the driving torque of the capstan shaft on the driving side increases, causing slippage between the capstan shaft on the driving side and the tape, making it difficult to run the tape stably.

The purpose of this invention is to provide stable rotation of the capstan by applying a stable load to the flywheel on the driven side, and to eliminate the need to make the flywheel on the driven side too large. It is an object of the present invention to provide a drive mechanism for a capstan shaft of a dual capstan type tape recorder in which rotation of the capstan shaft on the driving side is not adversely affected by a flywheel on the driven side.

The feature of this invention is that a permanent magnet and a magnetic material are fixed facing each other to the surface of the flywheel on the driven side and the surface of the stationary part opposite to this surface, so that the permanent magnet and the magnetic material are fixed to each other. The purpose is to apply appropriate viscosity, that is, load, to the flywheel and capstan shaft of the driven side by utilizing the hysteresis effect between the two.

Hereinafter, the present invention will be explained with reference to FIGS. 2 to 4.

In FIGS. 2 and 3, two chassis are constructed by a chassis 5 that supports various mechanical parts of the tape recorder, and a chassis 6 dedicated to the capstan section fixed at an appropriate interval below this chassis 5. Bearing holders 7 and 8 are held, and a driving capstan shaft 9 is held that axially passes through the bearing holder 7 and is rotatable via the bearings.
A driven side capstan shaft 10 passes through the other bearing holder 8 in the axial direction and is rotatable via the bearing.
is retained. Further, below the chassis 6, a fixed plate 11 is arranged in parallel under the interposition of struts 14, 14, and the lower ends of the capstan shafts 9, 10 are mounted on thrust receivers 12, 13 provided on the fixed plate 11. Each is listed. A rotor 15 that also serves as a flywheel is fitted and fixed to the capstan shaft 9, and a flywheel 16 is fitted and fixed to the other capstan shaft 10. These rotor 15 and flywheel 16 are connected to the chassis 6 and the fixed plate 11. It is located between. A concave portion is formed on the lower surface of the rotor 15, and a ring-shaped permanent magnet 17, which is magnetized with multiple poles in the circumferential direction, is fitted and fixed in this concave portion. A driving coil 18 is fixed on the fixed plate 11 facing the permanent magnet 17 with a predetermined gap between the driving coil 18 and the magnet 17. A rotor 15 and a capstan shaft 9, which are integrated, are adapted to rotate. Concave portion 1 on the upper surface of the rotor 15
5a is formed, and a large number of teeth 15b are formed in the shape of an internal gear wheel at equal intervals on the inner circumferential surface of this recessed portion 15a. In the recessed portion 15a, yokes 19 and 20 of a frequency generator held by the bearing holder 7 are arranged.
Teeth 19a formed at regular intervals on the circumferential surface of the rotor 15 face the teeth 15a of the rotor 15. A ring-shaped permanent magnet 21 is fixed between the two yokes 19 and 20, and a power generating coil 22 is fixed on the outer periphery of the magnet 21. and tooth 19a of yoke 19
The power generating coil 22 detects the magnetic change between the rotor 15 and generates a voltage corresponding to the rotation speed of the rotor 15. By controlling the energization of the drive coil 18 according to the output of the frequency generator, the rotor 15 is driven to rotate at a constant speed.

An endless belt 23 is placed between the rotor 15 and the flywheel 16, so that the rotational force of the rotor 15 is transmitted to the flywheel 16. A multipolar magnetized ring-shaped permanent magnet 24 as shown in FIG. 4 is fixed to the lower end surface of the flywheel 16, and faces the fixed plate 11 with an appropriate gap therebetween. There is. The fixed plate 11 is made of a magnetic material such as an iron plate, and attracts the permanent magnet 24 and the flywheel 16 integrated therewith, thereby pressing the capstan shaft 10 against the thrust receiver 13. . Note that the flywheel 16 may be made of a magnetic material such as iron, or a magnetic material may be fixed to the flywheel 16, and a permanent magnet may be fixed on the fixed plate 11 facing the flywheel 16.

Assuming that the rotor 15 is rotationally driven by energizing the drive coil 18, this rotational force is transmitted to the driven flywheel 16 via the belt 23.
The flywheel 16 is also rotationally driven. As the rotor 15 and flywheel 16 rotate, the driving side capstan shaft 9 and the driven side capstan shaft 10 also rotate, and two pinch rollers (not shown) press the tape against the two capstan shafts 9 and 10, thereby tightening the tape. The tape is transported at a constant speed from the left to the right in FIGS. 2 and 3, and the tape unwound from the supply reel is wound onto the take-up reel. The driven flywheel 16 is then moved to the capstan shaft 1 by the attraction between the magnet 24 and the fixed plate 11.
0 onto the thrust receiver 13. Furthermore, not only the inertia caused by the flywheel 16 acts, but also the residual magnetic effect between the permanent magnet and the fixed plate 11 acts as resistance and applies a predetermined load. As a result, the flywheel 16
A suitable viscosity is generated in the rotation of the flywheel 16, stable rotation can be obtained without making the flywheel 16 itself too large, and the rotation of the drive arm capstan shaft 9 is not adversely affected.

Note that the torque transmitted between the permanent magnet 24 and the fixed plate 11 based on the hysteresis effect that occurs between the permanent magnet 24 and the fixed plate 11
Tc can be expressed as Tc=K・Wh・Vh・N where Wh: Area of hysteresis loop Vh: Volume of hysteresis material (fixed plate) N: Number of magnetic poles of permanent magnet. Therefore, by changing the material of the fixed plate 11, which is a magnetic material, and the number of magnetic poles of the permanent magnet 24, the torque Tc and eventually the viscosity can be changed, and the gap between the permanent magnet and the fixed plate can be changed. The viscosity can be changed even when it is twisted. Further, in the illustrated example, the driving side capstan shaft is driven by a direct drive motor, but it may be driven by a motor provided elsewhere.

According to the present invention, the following effects are achieved.

(1) Since it does not use a compression spring like the conventional one, the frictional effect does not become unstable and stable rotation is achieved.

(2) Since a stable load can be applied to the driven flywheel due to the hysteresis effect between the permanent magnet and the magnetic plate, the rotation of the capstan is stabilized.

(3) There is no need to make the flywheel on the driven side too large, so there is no slippage between the capstan shaft on the driving side and the tape.
There is no adverse effect on the rotation of the drive capstan shaft.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view showing an example of a driven flywheel in a conventional dual-capstan tape recorder, FIG. 2 is a vertical cross-sectional front view showing an embodiment of the present invention, and FIG. 3 is a front view of the same. FIG. 4 is a plan view of a permanent magnet used in the above embodiment. 9... Driving side capstan shaft, 10... Driven side capstan shaft, 11... Fixed plate made of magnetic material, 15... Drive side rotor that also serves as a flywheel, 16... Driven side flywheel, 17... Rotor magnet, 18... Drive coil, 23... Belt, 24... Permanent magnet.

Claims (1)

[Claim for Utility Model Registration] In a tape recorder in which the tape is transferred by pressing a pinch roller against two capstan shafts, the capstan shaft on the downstream side of the tape, that is, on the drive side, is rotated by a capstan drive motor. The flywheel fixed to the capstan shaft on the downstream side and the flywheel fixed to the capstan shaft on the upstream side, that is, the driven side are connected by a belt, and the flywheel on the upstream side is connected with a belt. A permanent magnet magnetized with multiple poles in the circumferential direction is fixed to either the surface of the foil or the immovable surface facing this surface, and the other is made of a magnetic material and is made to face each other. A drive mechanism for a capstan shaft of a tape recorder, characterized in that a hysteresis effect and a magnetic attraction effect are produced between the two.