JPH0330935B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a capstan structure for a magnetic recording and reproducing apparatus that records and reproduces video by helically scanning a magnetic tape along a rotating drum.

[Prior art]

FIG. 1 shows the state of a conventional magnetic recording/reproducing apparatus before the tape is loaded, and FIG. 2 shows the state after the tape is loaded.

First, in FIG. 1, reference numeral 1 denotes a capstan shaft, which protrudes above a base 2. 3 is a cassette in which a magnetic tape 4 is housed. When the cassette 3 is installed, the rotating drum 5 is placed on one side of the magnetic tape 4, and the tape guides 6a, 6b, 6 are placed on the other side.
c, a pinch roller 7, and tape guides 8 and 9, respectively. When recording and reproducing the magnetic tape 4 from this state, the link guide 10 starts rotating by driving a loading motor (not shown), and the tape guides 6a, 6b, 6c sequentially move, as shown in FIG. As shown, the magnetic tape 4 is helically scanned by the rotating drum 5, and the magnetic head 1
1, the tape guide 12 and the pinch roller 7 are moved by a separate mechanism (not shown), and the magnetic tape 4 is sandwiched between the capstan shaft 1 and the pinch roller 7, and the magnetic tape 4 is driven. will be held.

FIG. 3 shows a conventional capstan structure. In this figure, reference numeral 13 denotes a pedestal fixed to the base 2, and the pedestal 13 is provided with a pair of bearings 14 and 15 that support the capstan shaft 1 with its tape engaging portion 1a sandwiched therebetween. . Reference numeral 16 denotes a motor as a rotation driving means, which includes a disc 18 fixed to the capstan shaft 1 via a bush 17 at the lower end side of the lower bearing 15, a magnet 19 fixed to the upper surface of this disc 18, and this magnet. A driving coil 2 fixed to a substrate 20 opposite to 19
1, and by applying a control voltage to this coil 21, the magnet 19 repulses and attracts,
The capstan shaft 1 rotates. Note that the substrate 20 is fixed to the lower surface of the pedestal 13.

Furthermore, magnets 22 which are alternately magnetized as NS are fixed to the outer periphery of the disc 18 in the circumferential direction.
A magnetic head 23 fixed to the base 2 facing the magnet 22 provides an output corresponding to the rotation of the capstan shaft 1, and the rotation of the capstan shaft 1 is controlled based on the output.

In the above-mentioned capstan structure, when playing back the magnetic tape 4, for example, when special playback such as slow play is performed, it is necessary to stop the rotation of the capstan shaft 1 in an extremely short period of time. There is a method of applying a rotational force to act as a brake, but the conditions vary widely and controlling the applied voltage becomes extremely complicated.
Therefore, a method is adopted in which a constant load is applied to the capstan shaft 1 to make it easier to apply the control voltage. However, in FIG. 3, the outer periphery of the magnet 22 is magnetized, and there is a risk that the rotation control ability will be impaired due to wear caused by the control device, demagnetization due to heat, etc. Furthermore, if the braking device is applied to the bottom surface of the disc 18, there is a risk that the magnet 19 and the coil 21 will come into contact with each other.

[Summary of the invention]

This invention was made to eliminate the above-mentioned drawbacks, and provides a capstan structure that can apply a stopping load without impairing rotational control performance by providing a braking device on the opposite side of the rotational drive means of the capstan shaft. The purpose is to

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings.

FIG. 4 is a side sectional view of a capstan structure according to an embodiment of the present invention. Components that are the same as those in FIG. 3 are given the same reference numerals.

In Fig. 4, 24 is a disk, and the upper bearing 1
4 is fixed to the capstan shaft 1 at the upper end side. 25 is a braking device that moves toward and away from the disc 24, and includes a bracket 26 fixed to the pedestal 13, a spring plate 27 supported by the bracket 26, and a braking device provided at the tip of the spring plate 27, which acts on the disc 24. Friction piece 28 pressed against the outer periphery and bracket 26
The plunger 2 is supported by the plunger 2 and pulls back the friction piece 28.
The solenoid 29 has a solenoid 9a.

The rest of the configuration is the same as the conventional one, so a description thereof will be omitted.

In the above configuration, when the rotation of the capstan shaft 1 is to be stopped in an extremely short period of time in order to perform special regeneration such as slowing, the power supply to the solenoid 29 is cut off and the friction piece 28 is moved by the spring force of the spring plate 27. It is pressed against the outer periphery of the disc 24. This applies a constant load to the capstan shaft 1,
It becomes easier to apply the control voltage to the motor 16. When it is no longer necessary to brake the capstan shaft 1, the plunger 29 is activated by energizing the solenoid 29.
a is pulled back, and the friction piece 28 is separated from the disk 24.

In addition, as shown in FIG. 4, the disc 24 is connected to the motor 16.
between the two bearings 1 and the bushing 17 that forms part of the
4 and 15, the movement of the capstan shaft 1 in the axial direction is suppressed. Therefore, even if the friction piece 28 of the braking device 25 is configured to act on the side surface of the disc 24, stable operating characteristics can be obtained. Although not shown in the drawings, it is also possible to provide a suitable mass to the disk 24 and form the disk 24 like a flywheel, for example, so as to absorb unevenness in rotational speed.

〔Effect of the invention〕

According to the invention described above, since the driving part and the braking part for the capstan shaft are provided separately from each other, a capstan structure is obtained that can apply a stopping load without impairing rotation control performance.

[Brief explanation of the drawing]

1 and 2 are top views of a conventional magnetic recording/reproducing device, FIG. 3 is a side sectional view of a conventional capstan structure, and FIG. 4 is a side sectional view of a capstan structure according to an embodiment of the present invention. be. 1... Capstan shaft, 1a... Tape engaging portion, 4... Magnetic tape, 5... Rotating drum, 1
4, 15...Bearing, 16...Rotation drive means, 24
... Disk, 25 ... Braking device. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A magnetic recording and reproducing device that records and reproduces video by aligning a magnetic tape with a rotating drum and performing helical scanning, comprising: a capstan shaft that engages and drives the magnetic tape; a pair of bearings that support the tape engaging portion at positions sandwiching it; a means for rotationally driving the capstan shaft on one bearing side; a disc fixed to the capstan shaft on the other bearing side; A capstan structure characterized by being equipped with a braking device that moves toward and away from a plate. 2. A capstan structure according to claim 1, in which two bearings are sandwiched between a disc and a rotational drive means to suppress movement of the capstan shaft in the axial direction. 3. The capstan structure according to claim 1, wherein an appropriate mass is given to the disk to absorb unevenness in rotational speed.