KR910009428Y1 - Tape speed control circuit in high speed search mode - Google Patents

Abstract

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Description

Tape speed control circuit in high speed search mode

1 is a conventional circuit diagram.

2 is a circuit diagram of this article.

3 is a timing diagram of frequency generation according to reel rotation.

* Explanation of symbols for the main parts of the drawings

SU: Supply Reel TU: Take Up Reel

DM: Drum B1-B2: FC Production Unit

D1-D2: Motor Drive MMV1-MMV2: Monostable Multivibrator

Q1-Q2: Transistor DMUX: Demultiplexer

VR1-VR2: Variable resistor C1-C4: Capacitor

R1-R6: resistance

The present invention relates to a tape speed control circuit such as a digital audio tape recorder or a digital video recorder, and in particular, in the high-speed search mode, the tape speed can be constantly adjusted by using a frequency generating signal according to the rotation of the supply and take-up reel. It is about a circuit.

In a system using a digital system such as a digital audio tape recorder, the speed of a tape must be constantly controlled to accurately extract various data recorded on the tape and perform a function according to the data.

FIG. 1 is a conventional circuit diagram, which is a circuit for controlling the speed of the tape in the high-speed search mode.

In the normal play mode, the circuit of FIG. 1 operates only in the high-speed search mode because the control of the take-up and supply reel motors is controlled by a capstan servo.

Referring to FIG. 1, the tape speed control in the conventional search mode will be described.

In fast forward mode, the tape travels from the supply reel (SU) side to the take up reel (TU) side, and the tape travels in the rewind mode. Proceeding from the reel (TU) side to the supply reel (SU) side.

In this case, it is assumed that the normal mode is a supply side, and the take-up side is a tape winding side.

Therefore, if the frequency generation signal according to the rotation of the supply reel 50 is called SFG (Supply Frequency Generator signal), and the frequency generation signal according to the rotation of the take-up reel 70 is called TFG (Take up Frequency Generator signal) The multiplexer MUX11 inputs TFG as the X0 selection terminal and SFG as the X1 selection terminal, and selectively outputs TFG or SFG as the X output terminal according to the fast search mode signal (FF) or rewind (REW).

Therefore, the TFG in the fast search mode and the SFG in the rewind operation are controlled to generate a constant FG signal in the phase locked loop circuit (PLL).

The output of the phase lock loop circuit PLL outputs TFG to the X0 output terminal and SFG to the X1 output terminal by the rewind (REW) / high speed forward (FF) signal from the demultiplexer MUX11. It is applied to the take-up reel motor and the supply reel motor through the driving units (D11-D12), respectively.

As described above, when the driving speed of the tape is controlled by using the PLL in the high-speed search mode, the rotation speed of the take-up reel TU is constant by using the frequency generation signal TFG of the take-up reel in the fast forward mode FF. In the rewind mode (REW), the rotation speed of the supply reel (SU) is kept constant, so that the running speed of the tape varies greatly according to the amount of tape wound on each reel.

In other words, the amount of tape wound on the take-up reel and the supply reel is different, and the rotation speed of the take-up and supply reel is kept constant regardless of the amount of winding of the tape. The actual tape running speed is extremely fast, which makes it difficult to extract data recorded on the tape.

Therefore, the purpose of this paper is to provide a circuit capable of accurately extracting data while maintaining a constant running speed of the tape regardless of the amount of take-up and supply reel tape winding in the high-speed search mode.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a specific circuit diagram of the present invention, which is composed of a supply reel (SU) and a first FG generating unit (B1), which generates first frequency signals according to rotation of the supply reel, take-up reel (TU), and second FG. And a second frequency generating means for generating a frequency signal according to the take-up reel rotation, the monostable multivibrator (MMV1), the variable resistor (VR1), the resistor (R1), and the capacitor (C1). A first control voltage generating means for generating a control voltage obtained by generating a pulse of a predetermined duty and generating a direct current at each occurrence of the first frequency, a monostable multivibrator (MMV2), a variable resistor (VR2), A second control voltage generating means composed of a resistor R2 and a capacitor C3-C4 for generating a control voltage obtained by generating a pulse of a predetermined duty every time the second frequency is generated to generate a DC voltage; and transistors Q1-Q2. ) And resistors (R3-R6) are switched in the search mode. A driving voltage generating means for synthesizing the first and second control voltages, a multiplexer (MUX), and motor driving units (D1-D2) to select the synthesized voltage by a rewind (REW) / fast forward (FF) signal. And a motor driving means applied to a supply or take-up reel motor. FIG. 3 is an operation waveform diagram of FIG. 2 to generate a pulse of a predetermined duty according to a frequency signal generated by rotation of the supply and take-up reel. It is shown.

Based on the above-mentioned structure, this draft is demonstrated in detail with reference to FIG. 1, FIG.

When the system is in normal play mode, the N / S signal is "high" and the transistors Q1-Q2 are switched "on" and rotation of the supply reel (SU) and take-up reel (TU) It is operated by a capstan motor regardless of the pulses of the supply and take-up reel.

That is, FIG. 2 does not operate in the normal mode and controls the driving of the reel motor only in the search mode.

At this time, when operating in the search mode (search mode), the N / S signal is applied to the "low" state from the microcomputer (not shown) to control the operation of the reel motor by switching the transistor (Q1-Q2) "f".

Then, according to the rotation of the supply reel SU, the first FG generation unit B1 generates the first frequency signal SFG as shown in (3a) and the second FG generation unit 82 according to the rotation of the take-up reel TU. Generates a second frequency signal (TFG) such as (3b).

In this case, the frequency of the first frequency signal SFG and the second frequency signal TFG varies depending on the amount of the tape wound on the supply reel SU and the take-up reel TU. When the amount of winding is large, the frequency becomes small. When the amount of winding of the tape is small, the frequency becomes large.

According to the first frequency signal SFG as shown in (3a), the monostable multivibrator MMV1 is inverted by the time constant of the external variable resistor VR1 and the capacitor C1. Generates a "low" pulse of a predetermined duty, such as furnace 3c, and according to the second frequency signal TGF such as 3b, the monostable multivibrator MMV2 is coupled to an external variable resistor variable resistor VR2 and a capacitor ( Inverting output terminal by time constant of C2) Generates a "low" pulse of a predetermined duty, such as furnace 36.

As can be seen from the above, when there is a large amount of tape wound on the supply reel (SU), there is less "low" pulse, such as t1 of (3c), and relatively less tape wound on the take-up reel (TU). "Low" pulses such as t2 in case (3d) often occur.

In addition, the opposite phenomenon occurs when the amount of tape wound on the supply reel (SU) is small.

The output pulses of the monostable multivibrators (MMV1-MMV2) are DC-powered by a low pass filter consisting of a resistor (R1) and a capacitor (C2) and a resistor (R2) and a capacitor (C3). Generates a control voltage for driving the reel motor.

The control voltage generated on the supply reel (SU) side and the control voltage generated on the take-up reel (TU) side are distributed through the resistors R3-R4, respectively, and are synthesized as R3 / R4. This voltage becomes the driving voltage of the reel motor. . Since the synthesized voltage for driving the reel motor is obtained by using the frequency generation signal according to the rotation of the supply and the take-up reel, the synthesized voltage can be used to control the running of the tape regardless of the amount of tape.

Rewinding the demultiplexer (DMUX) for inputting the synthesized voltage It selectively outputs according to the signal. When rewinding, the synthesized voltage is output to the X1 output terminal to drive the supply reel (SU) motor through the motor driving unit D2, and the high speed forward mode. At one time, the synthesized voltage is output to the X0 output terminal to drive the take-up reel motor through the motor driver D1.

At this time, if the reel speed is continuously increased, the t1 or t2 signal such as (3c) or (3d) is frequently generated and the DC voltage level is lowered, thereby maintaining the voltage applied to the motor properly.

In addition, determination of the reference speed of the reel motor determines the time constant by the monostable multivibrator (MMV1-MMV2) external capacitor and the variable resistor, and the time constant of the resistance (R3-R4) value motor driver D1-D2.

As described above, the motor driving voltage is generated by using the frequency signal according to the take-up and rotation of the supply reel in the high-speed search mode, and the driving speed of the tape can be maintained by applying the signal to the reel motor. The advantage is that you can extract accurate data.

Claims (3)

A data recording and reproducing system having means for generating a first frequency signal according to a rotation of a supply reel and a second frequency signal according to a rotation of a take-up reel, wherein the pulses of a predetermined duty are generated by generating a pulse of a predetermined duty every time the first frequency is generated. Means for generating a first control voltage, means for generating a second control voltage that is generated by directing a pulse of a predetermined duty every time the second frequency is generated, and operated in a search mode to be generated by rotation of both reels. Means for synthesizing the first and second control voltages to drive the reel motor by the sum of pulses, and means for driving the motor by selecting the synthesized voltage as a motor on the take-up or supply reel side according to the state of the search mode. Tape speed control circuit in the search mode, characterized in that the configuration. 2. The monostable multivibrator means according to claim 1, wherein the means for generating the first and second control voltages generates a pulse of a predetermined duty by the time constant of the external resistor and the capacitor each time a second frequency signal is generated according to the reel rotation. And means for generating a control voltage obtained by low-pass filtering the pulse output of the monostable multivibrator means to generate a DC voltage. The driving method of claim 1, wherein the motor driving means selects and drives the synthesized voltage to the take-up reel motor side during the high speed forward (FF) mode in the search mode, and selects and operates the synthesized voltage to the supply reel motor side during the rewind (REW) mode. And configured to.