JPH087548Y2 - Tape drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a tape drive device.

(B) Prior Art Japanese Patent Application Laid-Open No. 61-191181 (H04N5 / 783) discloses a tape drive device for driving a reel stand by a capstan motor in a video tape recorder (VTR). More specifically, it shows a configuration in which the tape speed is controlled to be substantially the same by controlling the rotation speed of the capstan motor based on the rotation information of the winding and supply reel base.

By the way, in a helical scan VTR, a tape loading operation of winding a tape around a guide cylinder having a rotary head is essential. In a so-called VHS type VTR, tape loading is generally performed only in a mode relating to reproduction and recording, and in a fast-forwarding, rewinding mode or stop mode, the tape is generally in an unloading state.

However, with such a configuration, it takes a long time to actually obtain an image at the start of reproduction (stop mode → reproduction mode), and improvement has been desired.

Therefore, a VTR that uses a mechanism called a full loading method for the purpose of shortening the image output time has been commercialized (for example, TV technology September '87 PP.44-49).
reference).

The problem with the full-loading method (here, the tape-loading mechanism is always executed when the cassette is loaded in the VTR) is to reduce the damage to the tape at the start of fast-forward / rewind. Is.
For this purpose, in P.47 of the above-mentioned known document, the reel motor is controlled so that the tape speed is gradually increased at the start of fast-forwarding / rewinding.

(C) Problems to be solved by the invention By the way, there are several types of motor arrangement in the mechanism of the VTR and the like. Although the reel motor and the capstan motor are provided independently in the above-mentioned publicly known documents, there is also a type in which the reel base is driven by the capstan motor. In such a mechanism in which the capstan motor is also used to drive the reel base, the rotation speed of the capstan motor is gradually increased at the start of the fast-forward and rewind modes, unlike the method disclosed in the above-mentioned known document. I have to do so.

(D) Means for Solving the Problems In the present invention, the control voltage of the capstan motor is gradually increased when the mode is changed from the stopped state to the fast-forward / rewind state. To this end, there is provided a first switch means connected between the control voltage line of the servo circuit and the reference potential point, and a series circuit of a capacitor and a second switch also connected between the control voltage line and the reference potential point. The first switch means is controlled by the PWM signal whose duty is gradually reduced, and the second switch means is controlled to be in the ON state at least for a predetermined period when the mode is changed.

(E) Action High voltage is supplied from the servo circuit of the capstan motor as soon as the mode is changed, but the first switch means is turned on by the PWM signal from the system control circuit. By being turned off, the supplied voltage gradually increases. Therefore, the tape speed can be gradually increased.

(F) Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment, and FIG. 2 is a waveform diagram for explaining the operation.

In FIG. 1, (1) is a capstan motor for driving a tape (driving a capstan and a reel base), 2
Is a servo circuit, 3 is an FG signal detection head of the capstan motor 1, 4 is a system control circuit (for example, a 4-bit microcomputer (LC66508) is used), 5 is a plurality of operation buttons, 6 is a first switch Means, 7
Is a capacitor, 8 is a second switch means, and 9 and 10 are resistors.

The servo circuit 2 creates and outputs a predetermined control voltage based on the FG signal of the motor (output of the detection head 3) and the set speed reference (depending on the tape running mode).

As described above, the syscon 4 uses a 4-bit microcomputer (LC66508). And Syscon 4
In addition to controlling the video circuit, mechanism, servo circuit, etc. of the VTR, it also controls microcomputers for other purposes (for example, timer recording control, remaining amount calculation, channel selection, etc.).

The syscon 4 also has a PWM pulse output terminal 4a for analog output. The duty of this PWM pulse can be changed by software over 256 steps. More specifically, this microcomputer (LC66508) has a built-in hardware that outputs a square wave (4KHz), and has the function of freely changing the duty of this square wave by software. That is why.

Then, when the tape running mode is changed, for example, when the stopped state is changed to the fast-forward (or rewind) state, the duty of the PWM signal starts from 60% for a predetermined period (when stop → fast-forward, about 6 seconds). It gradually decreases during the period and changes to zero. Also, the second switch means control signal from the terminal 4b is H during the period when the PWM signal is simultaneously output.
Syscon 4 is programmed to reach the level.

When the first switch means 6 is set to the ON state, the output control voltage of the servo circuit 2 is divided by the resistors 9 and 10. When the output of the terminal 4b becomes H level, the smoothing capacitor 7 is inserted.

Next, the operation will be described with reference to FIG. Fast forward / rewind (FF / REW) from stop (STOP) tape running mode
When the mode is changed (A), the output of the servo circuit 2 suddenly becomes a high voltage as shown by D. In fact, the PWM
By the signal B and the second switch control signal C, the voltage supplied to the motor changes as indicated by E. Then, the tape speed changes like F.

That is, the tape is gradually accelerated, and it is possible to prevent slack in the tape and strong tension applied to the tape.

(G) Effect of the Invention As described above, according to the present invention, the tape speed can be gradually increased and the tape slack and the tape damage can be prevented only by adding an extremely simple configuration. .

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the embodiment, and FIG. 2 is a waveform diagram for explaining the operation. 1 ... Capstan motor, 2 ... Servo circuit, 4 ...
Syscon, 6 ... First switch means, 7 ... Capacitor, 8 ... Second switch means

Claims (1)

[Scope of utility model registration request] 1. A capstan motor for driving a capstan, a voltage supply means for supplying a control voltage for driving the capstan motor, a supply line for this control voltage, and this supply line and a reference. A first switch means connected between the potential points, a series circuit of a capacitor and a second switch means which are also connected between the supply line and the reference potential point, and the duty gradually changes when the tape drive mode is changed. A PWM signal means for generating a PWM signal for controlling the first switch means, and a control signal for the second switch means for keeping the second switch means in an ON state for at least a period during which the PWM signal is supplied. A tape drive comprising a two-switch control signal generating means.