KR910003263Y1 - Servo signal circuit for head drum - Google Patents

Abstract

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Description

Drum Servo Reference Signal Generation Circuit

1 is a circuit diagram of the present article.

2 is an operational waveform diagram of FIG.

* Explanation of symbols for main parts of the drawings

R1-R8: resistor C1-C3: capacitor

Q1, Q2: transistor 10: frequency divider circuit

20: monostable multivibrator 30: Oagate

40: drum servo circuit

The present invention relates to a servo device of a Hi-Fi video tape recorder system (hereinafter, referred to as a VTR) system. In particular, a drum servo reference generating a vertical synchronizing signal which is a reference signal of a DRUM Servo It relates to a signal generating circuit.

In high fidelity VTRs, drum servos record and reproduce video and audio signals on magnetic tape that control the phase and rotation of the video head and drum rotation during recording and playback. The reference signals used here are separated from the video signals. Use one vertical sync signal. However, the reference signal generating circuit of the conventional Hi-Fi VTR is supplied when recording the audio signal while maintaining the video signal recorded on the magnetic tape of the broadcasting mode (Simulcast Mode) capable of separately recording and reproducing the video signal and the audio signal. There is no video signal and the output of the vertically configured synchronous signal detection circuit operates the pulse generator to issue a mood signal or to generate a reference signal by another option switch. Hassle to operate.

Accordingly, an object of the present invention is to brake a drum servo reference signal generation circuit capable of issuing a reference signal using color carriers even when no vertical synchronization signal is input to the hi-fi VTR.

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

1 is a circuit diagram of the present invention, in which R1-E8 is a resistor, C1-C3 is a capacitor, Q1 and Q2 are transistors, 10 is a divider, 20 is a monostable multivibrator, 30 is an oragate, and 40 is a drum servo. Circuit.

A synchronizing separator 60 for forming a low pass filter by the resistor R1 and the condenser C1 to separate the vertical synchronization signal from the video signal applied from the outside, and a plurality of resistors R2-E4 and the condenser C2. And a first amplifier 70 inverted and amplified by the transistor Q1 and output from the synchronous separation unit 60, and the inverted vertical synchronous signal as the resistor R5 and the transistor Q2. The buffer 80 for buffering and inverting the signal and a reset terminal are connected to the output of the first amplifier 70. The input of the color carrier is divided by a predetermined amount in synchronization with the output of the first amplifier 70. A divider 10 for issuing one pulse and a trigger terminal are connected to the output of the divider 10, and monostable for outputting a vertical synchronous signal as a second pulse in response to the input of the first pulse. Multivibrator 20, the buffer 80 and monostable multivibrator The ORA gate 30 is configured to logically combine the vertical synchronous signal and the second pulse output from the data 20 and output the same through the resistor R2, and is connected to the output of the OA gate 30 to be input to the vertical synchronous signal. The drum servo circuit 40 is configured to perform a drum servo operation.

2 is an operational waveform diagram of FIG.

The present invention will be described in detail based on the above configuration. First, when a video signal as shown in FIG. Only the vertical synchronizing signal, such as 2b, is separated by the time constant of the capacitor C1 connected between the second power sources GND, and is output to the first amplifier 70 through the connection point 1. The vertical synchronization signal of the connection point 1 is input to the transistor Q1 through the coupling capacitor C2. The transistor Q1 for inputting the vertical synchronization signal through the resistors R2 and R3 inverts and amplifies the vertical synchronization signal of FIG. 2b as shown in FIG. 2c and outputs it to the resistor R4.

At this time, the transistor Q2 that inputs the inverted-amplified vertical synchronization signal to the base through the resistor R4 is turned on and applied to the emitter only when the transistor Q1 is turned on, as shown in FIG. The inverted-amplified vertical synchronization signal is buffered and inverted as shown in the 2d diagram and inputted to the oragate 30 by outputting the first power supply VCC through the collector.

On the other hand, the divider 10 which inputs the inverted-amplified vertical synchronization signal like the 2c diagram in the first amplifier 70 as the reset terminal and inputs the color carrier which is inverted in the 2e degrees from the Y-C crystal oscillator as an input terminal. Is reset (output " low ") as R in Fig. 2f when the inverted-amplified vertical synchronization signal becomes " low ". When the inverted vertical synchronizer preference [Fig. 2c] output from the first amplifier 70 becomes "low" to "high", the divider 10 resets the color subcarrier inputted as the 2e diagram. A predetermined fractional ratio is divided to output a signal of a first pulse string (one cycle equal to the vertical synchronization signal) equal to the second frequency.

Therefore, the divider 10 divides and outputs the color subcarrier inputted in synchronization with the vertical synchronization signal when the vertical synchronization signal is input, so that the first pulse string is output in synchronization with the vertical synchronization signal. Therefore, the divider 10 generates and outputs a first pulse train having a duty ratio of greater than or equal to 50% and a second frequency in synchronization with the vertical synchronization signal.

The monostable multivibrator 20 for inputting the first pulse range equal to the second f diagram to the input terminal A is triggered when the signal of the first pulse string becomes the rising UP and is connected to the terminal T. By the time constant of the resistor R6 and the capacitor C3, the second pulse train having the same pulse width T (time constants of R6 and C3) as the second g degree is outputted to the output terminal Q, and the second h degree The same inverted signal is generated at the inverted output terminal Q connected to the input terminal B and output through the resistor R7.

Then, the oA gate 30 inputs the vertical synchronization signal of FIG. 2d outputted from the buffer 80 to the first input terminal, and simultaneously inputs the second pulse string of the second pulse, such as 2b, to perform a logical sum to synchronize the vertical synchronization signal. The reference signal is output to the drum servo circuit 40 through the generation resistor R8. At this time, the drum servo circuit 40 inputs the reference signal to perform a drum servo operation.

On the contrary, when the video signal is not applied from the outside (T2 cycle in FIG. 2), the two transistors Q1 and Q2 remain OFF, so that the collector of transistor Q1 is lowered as shown in FIG. The first power supply VCC applied through R5 and R4 is maintained, and the transistor Q2 collector maintains a low state as shown in the second degree.

At this time, the frequency division circuit 10 for inputting the color carrier (8sc = 3.58MHz) as the input terminal 2e and the first power supply Vcc on the collector of the transistor Q1 to the reset terminal is in a normal operating state (list And a frequency division of the color carrier at a predetermined division ratio, thereby generating and outputting a first pulse train having a duty ratio of 50% and having the same frequency as the vertical synchronization signal. [The waveform of the T1 cycle and the waveform of the T2 cycle among the waveforms of FIG. 2f differ only in duty ratio, but have the same frequency.

The monostable multivibrator 20 for inputting the first pulse train of the period T2 of the same period as the second f diagram to the input terminal A is triggered when the signal of FIG. 2f is rising (UP) to the resistor R6 and the capacitor C3. Is outputted to the output terminal Q. Therefore, the second pulse region equal to the vertical synchronization signal is output from the inverting output terminal Q of the monostable multivibrator 20, which is output through the resistor R7. The oar gate 30 which inputs the second pulse string to the second input terminal is turned off, thereby integrating the "low" signal (the output signal of the transistor Q2 outputting the 2d diagram and the second pulse string of the diagram 2h). A reference signal having a second pulse train such as 2i is output through the resistor R8. Then, the drum servo circuit 40 inputs the reference signal to perform a drum servo operation.

Therefore, as described above, this paper uses a color subcarrier of the Y-C crystal oscillator, which is a complex circuit including an option switch installed by issuing a reference signal even when the video signal is not applied from the outside, and a vertical synchronous signal detection circuit at no signal. There is an advantage of simplifying the operation and eliminating the need to operate the option switch.

Claims (1)

A servo device of a hi-fi VTR system having a drum servo circuit 40 for inputting a vertical synchronous signal to perform a drum servo operation, comprising: a synchronous separator 60 for inputting a video signal to separate a vertical synchronous signal; A first amplifier 70 connected to an output terminal of the synchronous separation unit 60 and inverted amplified input synchronous signal to output an inverted amplified vertical synchronous signal, and connected to the first amplifier 70 A buffer 80 for generating a vertical synchronization signal inverted by inverting and buffering the inverted amplified vertical synchronization; and an output of a Y-C crystal oscillator and an output of the first amplifier 70. A divider 10 for synchronously dividing and outputting the color subcarrier output from the C crystal oscillator to the vertical synchronization signal output from the first amplifier 70, and a trigger terminal connected to an output of the divider 10, And a monostable multivibrator 20 for generating and outputting a second pulse having the same period as the vertical simultaneous signal in response to the input of the first pulse, and the buffer 80 output and the monostable multivibrator 20. A dream servo is composed of an orient 30 that inputs a reference signal, such as the vertical synchronization signal, to the drum servo circuit 40 by synthesizing the generated vertical synchronous signal and the second pulse string connected to an output of the second synchronous signal. A drum servo quasi-signal generating circuit specially designed for the case.