KR860001993Y1 - Tracking indicating arrangement - Google Patents

Abstract

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Description

Tracking display circuit of magnetic recording and reproducing apparatus

1 is a circuit diagram of the present invention.

* Explanation of symbols for main parts of the drawings

1: playhead 2: preamplifier

3: envelope amplifier stage 4: current and voltage amplifier circuit

5: amplification factor adjustment circuit 6: half-wave rectifier circuit

7 current amplification circuit 8 light emitting display

9: FM demodulation unit SYSCOM: System control computer

The present invention relates to an electronic circuit capable of visually displaying a tracking state between a head and a video tape in a hi-fi VTR.

In recent years, the magnetic recording and playback apparatus has been designed to optimally adjust the tracking state between the head and the video tape so that a high quality screen and sound can be watched. I can do it. Therefore, you can get a good picture with the tracking adjustment as described above for viewing, but more precise tracking in the case of a program (such as playing a music tape for listening to music) that needs to reproduce delicate and high sound quality. Adjustment is required. That is, the video system and the audio communication call can be reproduced with the lowest noise at the same time only when the tracking adjustment is adjusted to the most optimal state. However, as a conventional adjustment method of tracking adjustment while checking the changing screen, high quality magnetic recording is performed. Since the high accuracy and precision required by the reproducing apparatus could not be obtained, a countermeasure was required.

The present invention complements the problems of the conventional tracking adjustment method described above. By displaying the tracking state on a plurality of light emitting elements, the display can be easily and accurately adjusted to an optimal tracking state by viewing the display. In order to achieve a higher playback effect on both sides of the sound quality.

Hereinafter, the configuration, operation, and effects of the present invention will be described in detail with reference to the accompanying drawings.

The present invention is connected to the current and voltage amplifier circuit 4, one end of the output of the envelope amplifier 3, which is in turn connected to the playhead (1) and the preamplifier (2), the end of the current and voltage amplifier circuit (4) An amplification factor adjustment circuit 5 is connected to compensate for the envelope output reduction during long time regeneration, while a half-wave rectifier circuit 6 is connected to the output side thereof, and a current amplifier circuit 7 is connected to the output side of the half-wave rectifier circuit 6. On the output side of the current amplifying circuit 7, a resistor R ₁₂ (R ₁₄ ) (R ₁₆ ), a light emitting diode (LED ₁ ) (LED ₂ ) (LED ₃ ), and a transistor (TR) having a constant difference in resistance value ₅ ) A light emitting display unit 8 composed of TR ₆ and TR ₇ is connected.

Reference numeral 9 denotes an FM demodulator and SYSCOM denotes a system control computer.

1 shows the specific circuit speed of the present invention having the above-described structure, wherein the video signal detected by the reproduction head 1 is applied to the envelope amplifier 3 after being amplified by the preamplifier 2. The envelope amplification section 3 amplifies the front end signal and outputs a part of the signal to the current and suppression amplification circuit 4 of the present invention, and outputs the remaining signal to the FM demodulation stage 9 for various image processing systems. Will be authorized.

The envelope signal is output to the current and the voltage amplifying circuit 4 is applied to a voltage amplifier built into the rear side transistor (TR ₂₎ the current amplified by the transistor (TR _1). In this case, when the selected mode is SP (standard play), a low level signal is output from the output terminal X ₃ of the SYSCOM to turn off the switching transistor TR ₃ so that the current and voltage amplification are performed. There is no influence on the emitter resistance side of the circuit 4. On the other hand, when the selected mode is extended play (EP; extended play), the signal output from the envelope amplifier stage 3 is weaker than that of the normal playback (SP), but the high level signal output from the SYSCOM is an amplification factor adjusting circuit. To compensate for this. That is, during long time reproduction, a high level signal is output from the output terminal X ₃ of the SYSCOM and applied to the base side of the switching transistor TR ₃ . Accordingly, since the transistor TR ₃ is turned on and the resistor R ₇ is connected to the ground side, the emitter side resistance of the voltage amplifying transistor TR ₂ is reduced. The reduction of the emitter side resistance increases the overall amplification degree of the voltage amplifying transistor TR ₂ , so that the long time reproduction signal output from the envelope amplification stage 3 and amplified by current and voltage is amplified to the same size as the signal during normal reproduction. The operation of the amplification factor adjusting circuit 5 is performed only at the time of reproduction for a long time to supply a signal source having a size required at a later stage.

The signal amplified by the current and voltage amplifier circuit 4 is applied to the half-wave rectifier circuit 6, half-wave rectified and then applied to the current amplifier circuit 7 operated by the transistor TR ₄ and amplified.

The amplified current between both ends there appears a voltage drop of the resistor (R _11), so the flow resistance (R _11), some of the current flows to the resistor _{(R 12) (R 14)} (R 16).

As described above, the resistors R ₁₂ (R ₁₄ ) (R ₁₆ ) have a constant difference in resistance value, that is, if the resistor R ₁₂ is 100 μs, for example, the resistors R ₁₄ are 200 μs and the resistors R ₁₆ ) is set in the order of 300Ω.

When the resistors R ₁₂ (R ₁₄ ) and R ₁₆ have the smallest width of the resistor R ₁₇ as in the above example, the transistor TR is preferentially dependent on the magnitude of the current flowing from the current amplifier circuit 7. ₅ ) the turn-on condition is satisfied. That is, when the inrush current is small, only the transistor TR ₅ is turned on so that the light emitting diode LED ₁ is turned on. In the case where the inflow current is large, the light emitting diode LED ₇ also satisfies the turn-on condition until the transistor TR ₇ is emitted. the diodes _{(LED 1) (LED 2)} (LED 3) it is lit both.

Here, the magnitude of the signal output from the current amplifier circuit 7 to the light emitting display section 8 is directly proportional to the magnitude of the signal output from the envelope amplifier stage 3, and the signal of the envelope amplifier stage 3 is optimally tracked. Since the light emitting display portion LED ₁ (LED ₂ ) (LED ₃ ) is all lit up in the adjusted state, it indicates that the tracking adjustment is in an optimal state. Accordingly, the user can find the optimal tracking state by adjusting the tracking volume so that the entire light emitting diode is turned on while looking at the number of light emitting diodes that are turned on in the light emitting display unit 8.

In the drawings of the present invention, the number of light emitting diodes is set to three for convenience, but in practice, the number of light emitting diodes can be increased.

The amplification degree and the numerical value of each element are appropriately set according to the correlation between the driving voltage of the light emitting display unit 8 and the actual tracking signal.

As described above, the present invention allows the user to visually display the tracking state with a relatively simple circuit configuration so that the user can see it and adjust the tracking state to an optimal state, thereby reducing noise to the lowest state in terms of not only image quality but also sound quality. It has the advantage of contributing to the improvement of the function of the high quality magnetic recording and reproducing apparatus which should reproduce the signal.

Claims (1)

The output side of the envelope amplifier stage 3, which is in turn connected to the regeneration head 1 and the preamplifier 2, is connected to the current and voltage amplifier circuit 4, and at one end of the current and voltage amplifier circuit 4 is an envelope for long time reproduction. An amplification factor adjusting circuit 5 for compensating for the output reduction is connected, while a half-wave rectifier circuit 6 is connected to the output side thereof, and a current amplification circuit 7 is connected at the output side of the half-wave rectifier circuit 6, and a current amplification circuit is provided. On the output side of the circuit 7, a resistor (R ₁₂ ) (R ₁₄ ) (R ₁₆ ) and a light emitting diode (LED ₁ ) (LED | ₂ ) (LED ₃ ) and transistor (TR ₅ ) ( TR ₆ ) A tracking display circuit of a magnetic recording and reproducing apparatus, in which a light emitting display section 8 composed of (TR ₇ ) is connected to visually display a tracking state.