JPS63167689A - Driving device for rotary body - Google Patents

Abstract

PURPOSE:To quicken the characteristic of response upon the rise-up of rotation, by a method wherein a rotating period information signal is not supplied to a rotating period control means until the period of rotation of a driving motor arrives at a predetermined period of rotation. CONSTITUTION:The switch 4 of a controller 3 is turned OFF upon starting a driving motor 2. Accordingly, the supply of a FG pulse to a rotary speed control circuit 6 is interrupted and a voltage control signal for outputting a high driving voltage for rotating the driving motor 2 quickly is outputted from the rotary speed control circuit 6. When the pulse width of the FG pulse has arrived at a predetermined pulse width of FG pulse, the controller 3 turns the switch 4 ON. According to this operation, the FG pulse is supplied to the rotary speed control circuit 6 through the switch 4 and a closed-loop rotary speed control circuit for the driving motor 2 may be formed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a drive device for a rotating body.

[Conventional technology]

In recent years, VTRs have become significantly more compact and lightweight, and as a result, the structure of the rotating drum that holds the rotating head is also desired to be thinner and more precise.

Some conventional rotating drum structures have a ball bearing support structure, but this requires a certain distance between the bearings (bearing span), and there is a limit to how thin the rotating drum can be made.

Furthermore, since the shaft and rotating body rotate while contacting each other via bearing balls, play occurs over time, which deteriorates rotational accuracy.

Furthermore, recently, dynamic pressure fluid bearings have been used as bearings in place of the ball bearings in order to improve the accuracy and reduce the thickness of rotating drums.

[Problem that the invention seeks to solve]

However, as is well known, the hydrodynamic bearing generates fluid force in the fluid filled between the shaft of the rotating body and the bearing when the rotating body rotates, and further functions as a bearing that increases the flow. It is something.

Conventionally, the rotation of the motor that drives the rotation of the rotating body is controlled using a closed-loop control circuit, but when the motor is started, the rotating body starts rotating slowly due to the action of the control circuit, It takes time to reach a rotational speed at which pressure is generated in the fluid, and during this time the fluid bearing may not operate normally as a bearing, resulting in poor response characteristics at startup.

The present invention was tried to solve the above problems,
It is an object of the present invention to provide a rotating body driving device that has a simple configuration, has a hydrodynamic pressure fluid bearing, has a quick response when a rotating body starts to rotate, and has good drive efficiency.

[Means to solve the problem]

A rotating body driving device of the present invention is a device that drives the rotation of a rotating body having a hydrodynamic bearing, and includes a drive motor that rotates the rotating body, and a rotation period information signal that detects a rotation period of the drive motor. a detection means for outputting a rotation period information signal outputted from the detection means, a rotation period control means for controlling the rotation period of the drive motor so that it is maintained at a first rotation period, and the detection means and a cutoff means for monitoring the rotation period information signal output from the rotation period information signal and cutting off the supply of the rotation period information signal to the rotation period control means until the rotation period reaches the second rotation period.

[For production]

With the above configuration, the rotation period information signal is not supplied to the rotation period control means until the rotation period of the drive motor reaches a predetermined rotation period, thereby quickly changing the rotation period of the drive motor to the second rotation period. It is possible to speed up the response characteristics at the start of rotation of a rotating body having a hydrodynamic bearing.

〔Example〕

Hereinafter, the present invention will be explained using one embodiment of the present invention.

FIG. 1 is a schematic diagram showing the structure of an embodiment of the present invention in which the present invention is applied to a rotating drum drive device for a VTR.

FIG. 2 is an operation timing chart of each part of FIG. 1.

In FIG. 1, when the drive motor 2 that drives the rotation of the rotary drum l having a hydrodynamic bearing is activated (point A in FIG. 2), the rotary drum l is in a stationary state, and the controller 3 initially A control signal of "0" level is supplied to the switch 4 as a state. This switch 4 is in the OFF state when the supplied control signal is at the "O" level, and the FG pulse is output from the FG detector 5 which detects the rotation period of the rotary drum drive motor 2 and outputs the corresponding FG pulse. The F
The supply of G pulses to the rotation speed control circuit 6 is cut off, and rotation control is performed by an open loop control circuit. In other words, when the FG pulse is not supplied, the rotation speed control circuit 6
It is determined that the drive motor 2 is in a stationary state, and a voltage control signal is outputted in a motor drive circuit 8, which will be described later, to output a high drive voltage v1 for rapidly rotating the drive motor 2. After this voltage control signal has excess signal components removed by a compensation filter 7 in order to stabilize the control,
The voltage v1 is supplied to the motor drive circuit 8, and the drive voltage v1 is applied from the motor drive circuit 8 to the drive motor 2 as described above, and the rotation of the rotary drum l is started. The drive voltage v1 is the voltage output from the motor drive circuit when the drive motor 2 is controlled to the fastest rotation speed by the rotation speed control circuit 6.

When the rotation of the rotary drum l is started as described above, an FG pulse as shown in FIG. After that, it is supplied to the controller 3 and switch 4.

The controller 3 monitors the supplied FG pulse width,
After the FG pulse width reaches a predetermined FG pulse width T, "l"
" level control signal is supplied to the switch 4. In other words, as shown in FIG.
While the FG pulse width T is being supplied to the controller 3, a control signal of "0" level is output from the controller 3 as shown in FIG.
After the signal is supplied to the switch 4, the controller 3 outputs an “L” level control signal as shown in FIG. 2a), and the switch 4
is in the ON state, and F output from the waveform shaping circuit 10
The G pulse is supplied to the rotation speed control circuit 6 via the switch 4. The FG pulse width T is a pulse width corresponding to the rotation period of the rotary drum 1 in a state where the hydrodynamic bearing provided on the rotary drum 1 acts as a bearing. Furthermore, until the control signal of "L" level is output from the controller 3, the motor drive circuit 8 is operated as shown in FIG.
The drive voltage vI is output from the drive motor 2, and the drive motor 2 is controlled to accelerate its rotation, but when the switch 4 is turned on,
After the state is reached, the FG pulses are supplied to the rotational speed control circuit 6, thereby forming a closed-loop rotational speed control circuit for the drive motor 2, and the FG pulses supplied from the rotational speed control circuit 6 are A voltage control signal for controlling the drive voltage output from the motor drive circuit 8 according to the FG pulse width and converging the drive motor 2 to a predetermined rotational speed is output to the motor drive circuit 8 via the compensation filter 7. be done.

For example, from the motor drive circuit 8, as shown in FIG.
After this point, the rotation of the drive motor 2 approaches the predetermined rotation speed, so there is no need to accelerate the rotation speed, so the drive voltage output from the motor drive circuit 8 is changed from V to V according to the width of the FG pulse. Gradually lower the rotation speed control circuit 6
controlled by

As described above, when a rotating drum having a hydrodynamic bearing is started to rotate, the hydrodynamic bearing of the rotating drum is controlled in an open loop so that the rotational speed of the drive motor is reduced to the speed at which the hydrodynamic bearing of the rotating drum acts as a bearing. By controlling the rotation speed of the drive motor to keep it constant using closed-loop control after reaching that speed, the rotation speed of the rotary drum can be increased with a simple configuration and a fast response time at startup. Can be controlled.

Although this embodiment has been described using a rotating drum drive device having a hydrodynamic bearing as an example, the present invention is not limited to this, and the present invention can be applied to any rotating body having a hydrodynamic bearing. You can apply it to get the same effect.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a rotating body drive device having a simple configuration, which has a dynamic pressure fluid bearing, has a quick response when the rotating body starts up, and has good drive efficiency.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the structure of an embodiment of the present invention in which the present invention is applied to a rotating drum drive device for a VTR. FIG. 2 is an operation timing chart of each part of FIG. 1. l... Rotating drum, 2... Drive motor,
3...Controller, 4...Switch, 5
... FG detector, 6... Rotation speed control circuit, 7... Compensation filter, 8... Motor drive circuit, 9... Amplifier, lO... Waveform shaping circuit.

Claims (1)

[Scope of Claims] A device for driving the rotation of a rotating body having a hydrodynamic bearing, comprising: a drive motor that rotates the rotating body; and a rotation period of the drive motor that is detected and a rotation period information signal outputted. a detection means; a rotation period control means for controlling the rotation period of the drive motor to be maintained at a first rotation period in accordance with a rotation period information signal output from the detection means; a rotation period information signal that monitors a rotation period information signal, and cuts off the supply of the rotation period information signal to the rotation period control means until the rotation period reaches a second rotation period. Drive device.