JPS5824038Y2 - Rotary head drum drive device in recording and reproducing equipment - Google Patents

Description

[Detailed Description of the Invention] The present invention is characterized in that a belt is stretched between a first pulley for driving a rotary head drum and a second pulley of a drive mechanism, and the rotation of the second pulley is controlled by the first pulley. The present invention relates to a rotary head drum drive device in a recording/reproducing device, in which the information is transmitted to a pulley of a rotary head.

For example, in a VTR, when a rotary head drum is rotationally driven by a motor, a transmission device is generally used for winding.

That is, a rubber belt is stretched between a pulley fixed to the drum shaft and a bobbin fixed to the rotating shaft of the motor to transmit rotational force.

According to the transmission device, this winding exhibits excellent features such as the drive device being inexpensive and the vibrations of the motor being absorbed by the rubber belt and not transmitted to the rotating drum.

However, since extremely high rotational precision is required for the rotating drum head, the belt used must be highly homogenized in quality and shape in the longitudinal direction.

For this reason, a lot of manpower is required to manufacture and inspect the belt, and the above-mentioned economic efficiency of low cost cannot be achieved sufficiently.

Therefore, it is known to transmit rotational force by wrapping multiple belts, for example, two belts with half the thickness, side by side.
According to this method, there is a problem that a sudden load is applied to the belt at the time of start-up, and the belt vibrates, resulting in poor start-up percentage.

The present invention has been made in view of such problems, and in the rotary head drum drive device of the recording and reproducing apparatus, the outer circumferential surfaces of the first and second boobies are configured to have a medium height, and the belt is composed of a plurality of rubber flat belts formed from the same material and in the same shape, and these plurality of flat belts are stacked on top of each other, and only the bottom layer flat belt is in contact with the first and second bools. The present invention relates to the rotary head drum drive device in a recording/reproducing apparatus characterized in that the rotary head drum drive device is arranged between pulleys.

Therefore, according to the present invention, it is possible to effectively prevent variations in rotational speed due to non-uniform belt ratios, and to provide a winding transmission device with excellent starting characteristics.

An embodiment in which the present invention is applied to a drive device for a rotary head drum of a VTR will be described below with reference to the drawings.

As shown in FIG. 1, a rotary head drum 1 of a VTR has a cylindrical shape that is flat in its axial direction, and a pair of video magnetic heads 2 are attached to its lower surface.

The magnetic head 2 is disposed on the outer peripheral surface of the head drum 1 so as to slightly protrude.

The rotary head drum 1, on which the magnetic head 2 is mounted in this manner, is fixed to the rotary shaft 4 via the mounting plate 3.

This rotating shaft 4 includes a bearing 6 fitted to a fixed guide drum 5 disposed below the head drum 1, and a bearing 6 that supports the fixed drum 5 and is held in the chassis via a bracket (not shown). It is rotatably supported by a bearing 8 fitted into a casing 7.

In the figure, 9 is a brake rotor core fixed to the rotating shaft 4, and 10 is a brake coil, and the rotor core 9 and coil 10 constitute an electromagnetic brake for the rotary head drum 1.

Furthermore, a pulley 11 is fixed to the lower end of this rotating shaft 4.

On the other hand, a pulley 14 is also fixed to an output shaft 13 of a motor 12 for driving the head drum 1.

The outer circumferential surfaces of these l pairs of pulleys 14 and 15 are configured to have a medium height, and between these pulleys 14 and 15, as shown in FIG. A pair of flat bells N5 and 16 are hung over each other,
As a result, the head drum 1 is configured to be rotationally driven.

These flat bells N5 and 16 are made by cutting a cylindrical rubber seam N7 by making a number of cut lines 18 in the circumferential direction of the cylinder, as shown in Fig. 3. There is an endless structure.

And the rubber flat bell N5 formed in this way,
16 are shifted between the pulleys 11 and 14 in the circumferential direction of the cylindrical sheet 17.
Inconsistencies in quality and shape of these rubber belts 15, 16 can be compensated for.

That is, by using the belts 15 and 16 in an overlapping manner, it is possible to effectively prevent fluctuations in the rotational speed caused by non-uniformity in quality and shape of the bells 15 and 16.

Therefore, the accuracy of the flat bell 1-15, 16 does not need to be very high.

In addition, in a steady driving state (that is, a state other than a transient state such as during startup), the external force between both flat bells N5 and 16 is reliably transmitted due to the frictional force that acts between the overlapping flat bells H5 and 16. This prevents the flat belt 16 from slipping and coming off during driving.

Further, since the pulley is of medium height, the bell 1-15.16 is centered at the center of rotation and runs in the center of the pulley.

Furthermore, since the inner diameters of the flat bells N5 and 16 are made to have the same size, the tension of the outer belt 16 is greater than that of the inner belt 15, increasing the stability ratio during running.

For these reasons, the running of Bell 1-15 and 16 will not become unstable.

Furthermore, since the pair of flat belts 15 and 16 are rubber flat belts formed from the same material and in the same shape, the upper layer flat belt 16 is stretched more than the lower layer flat belt 15. The shrinkage of the flat belt 15°16 in the width direction is also proportional to this.

Therefore, the width of the upper layer flat belt 16 is the lower layer flat belt N5 (/
The upper layer 0 flat belt 16 does not protrude sideways from the lower layer flat belt 15 due to the width being smaller than the J width, and only the lower layer flat belt 15 is always in direct contact with the boots IJ 11 and 14. .

Therefore, in a steady driving state, the torque of the pulley 14 is first transmitted to the flat belt 15, and then a part of the transmission force is transmitted from the flat belt 15 to the flat belt 16 due to the friction between the flat belts 15 and 16. Ru.

The several thousand bells t-15 and t-16 then share the transmission force with each other and reliably transmit the torque to the driven pulley 11.

However, in a transient driving condition, for example, when an excessive instantaneous starting torque of the motor 12 is transmitted to the pulley 14,
The inertial force of the transmitted system on the pulley 11 side is
The moment of inertia of the rotary head drum 1 and the like is large, and the angular acceleration is also large due to instantaneous torque, resulting in a large value, and the pulley 11 hardly tries to rotate.

On the other hand, the pulley 14 and the flat belt 15 will slide relative to each other even in response to such excessive torque, and the frictional force between the portions of the flat belts 15 and 16 wound around the pulley 14 will increase. is normally smaller than the shearing force that should be transmitted from flat belt 15 to flat belt 16 based on this excessive torque, so a relative slip occurs between flat belts 15 and 16, and only flat belt 15 is made of rubber. It resists elasticity, expands greatly on the tension side, and contracts greatly on the compression side, absorbing the activation energy.

Therefore, excessive starting torque will not adversely affect the device.

By the way, the flat belt 15 that has been deformed as described above may induce vibrations due to the elasticity of the rubber at the next moment.
Since this vibration is rapidly attenuated and eliminated by the frictional force between the parts of the belts 15 and 16 wound around the pulley 14, there is no possibility that the apparatus will be adversely affected by the vibration even at this stage.

As the magnitude and variation of the torque to be transmitted settle down over time, the magnitude and variation of the shear force transmitted from the pulley 14 to the flat belt 15 also gradually decrease. The shear force that should be transmitted between the belts 15 and 16 becomes smaller due to the frictional force between the belts 15 and 16, and therefore the slippage between the belts 1 and 15 and 16 is reduced to 1.
Therefore, the force to be transmitted to the pulley 11 is
By ゜16, it becomes possible to share.

However, as the time passes, the inertial force on the pulley 11 side also decreases in proportion to the decrease in angular acceleration.
is gradually accelerated, and the drive device eventually enters a steady drive state.

In this way, the rotating head drum 1 is not exposed to instantaneous excessive torque, and the starting of the rotating head drum 1 is extremely smooth.

Also, the tape etc. will not be damaged.

In addition, the lateral vibration that occurs in the Heiko belt due to the elasticity of the flat bell) 15 and 16 is caused by the overlapping of the Heiko belts 15 and 16.
Since the natural frequency also differs in proportion to the square root of the tension, even if vibration is induced, both flat belts t-15 and t-16 collide with each other at the vibrating portions, rapidly attenuating and extinguishing the vibration.

Therefore, there is no risk of inducing rotational unevenness in the rotary head drum 1.

Although the present invention has been described above with reference to embodiments, the present invention is not limited to the above-mentioned embodiments, and various modifications can be made based on the technical idea of the present invention.

For example, in the above embodiment, the present invention is applied to a drive device for a rotary head drum of a VTR, but the present invention can also be applied to various other winding transmission devices, such as a capstan drive device in a tape recorder. Is possible.

In the above-described embodiment, two belts 15° and 16 are used in a stacked manner, but the present invention is not limited to the use in which two belts are used in a stacked manner, and three or more belts may be used in a stacked manner. good.

As described above, in the present invention, since the outer peripheral surfaces of the first and second pulleys are formed to have a medium height, even if a plurality of rubber flat belts are stacked on top of each other and placed between the pulleys, the rubber flat belts can be In cooperation with the frictional force generated in the flat belt, the flat belt hooking in a steady state reliably prevents the belt from coming off.

Since multiple flat belts are usually made of the same material and have the same shape, local shape defects on the inside and outside of each flat belt, as well as non-uniformity in the material, can be caused in the longitudinal direction of the flat belt. Due to the random distribution, the service life of the transmission device is significantly improved.

The occurrence of uneven rotation, etc., is also prevented, and since the precision of the belt may be low, the belt can be manufactured at a low cost.

Further, in the plurality of flat belts stacked on top of each other, only the lowest layer flat belt is in contact with the first and second pulleys. When the starting torque is transmitted, the inertial force of the transmitted system causes the adjacent flat belts to slide against each other, and as a result, only the lowest flat belt stretches and absorbs the starting torque. Without being exposed to torque, the rotating head drum starts extremely smoothly.

It does not cause any damage to tape, etc.

In addition, the lateral vibration that occurs in the flat belt due to its elasticity also
Since the flat belts overlap each other and have different natural frequencies, they collide with each other at their vibrating parts and are rapidly attenuated and extinguished.

Therefore, there is no risk of inducing rotational unevenness in the rotating head drum.

[Brief explanation of the drawing]

The drawings show an embodiment in which the present invention is applied to a drive device for a rotary head drum of a VTR. ■
3 is a perspective view of a sheet 17 for making a belt 15, 16. In addition, in the symbols used in the drawings, 11...
・Pulley, 14...Pulley, 15...
Flat belt, 16... Flat belt.

Claims (1)

[Scope of utility model registration request] A record in which a belt is stretched between a first pulley for driving a rotary head drum and a second pulley of a drive mechanism, so that rotation of the second bobbin is transmitted to the first bobbin. In a rotary head drum drive device in a playback device,
The outer peripheral surfaces of the first and second pulleys are configured to have a medium height, and the belt is configured of a plurality of rubber flat belts formed from the same material and in the same shape, and the plurality of flat belts are overlapped with each other and 1. A rotary head drum drive device for a recording/reproducing apparatus, characterized in that only the flat belt of the lowest layer is stretched between the first and second pulleys with only the flat belt being in contact with the first and second pulleys.