KR950001244B1 - Method of and circuit of finding tracks in video tape recorder - Google Patents

Abstract

The circuit checks capstan phase control, write-mode detector, auto tracking finding lock. The circuit consists of pilot comparator (10) with reference ATF (1), 1, 2 BPF, 1, 2 peak detectors (4,5), OP amp (6), comparing PB pilot with reference pilot, low pass filter (20) for flatting ATF error signal (11) for capstan phase control, buffer (C1) for shaping ATF error signal for detecting PB and write-mode, a S/H pulse generator with inverter (C3) and AND gate (C4) for generating sampling and hold pulse for detecting ATF lock, S/H block (30) for holding data of buffer.

Description

Advanced Auto Tracking Finding Circuit and Method of Video Tape Recorder

1 is a circuit diagram of the present invention.

2 is a timing diagram according to the present invention.

3 is a flow chart according to the present invention.

* Explanation of symbols for main parts of the drawings

10: pilot comparison unit 20: low pass filter unit

30: S / H part C1: buffer

C2: endgate C3: inverter

TECHNICAL FIELD The present invention relates to an 8mm video tape recorder (hereinafter referred to as a VTR), and in particular, an advanced method, capstan phase control and recording mode detection, and auto tracking finding (Auto tracking). Tracking Finding (hereinafter referred to as ATF) relates to a circuit and a method of an ATF system for checking a lock.

In general, the head of the ATF system 8mm VTR controls the video tracking automatically.

Conventionally, the signal difference is detected by equilibrium modulation of a playback ATF signal and a reference ATF signal.

If the detection does not match the tracking, the OP Amp (OP) output is changed to high or low, and the tracking operation is automatically performed after the capstan motor phase is increased or decreased. .

In this case, locking means that a 1-channel head traces a 1-channel track, and according to the characteristics of the ATF system, the order of the PB ATF and the reference pilot signal must be correct.

If the order is not correct, the head skips about one frame and noise occurs on the screen.

Therefore, the semiconductor ATF lock must be checked, which holds the ATF error for a while to control the capstan phase while checking the ATF lock in between.

The reason for holding the error here is that the error is disturbed during the lock check.

In order to do the above, the ATF error holding signal and the ATF lock check signal were required.

Therefore, a control signal for sampling / holding was necessary and there was a problem in servo stability as a forced control during the holding period due to the capstan phase control discontinuously in the time domain.

Therefore, an object of the present invention is to include all information on an ATF error and simultaneously solve various situations such as capstan phase control, write mode detection, and ATF lock check without sampling and hold. The present invention provides an advanced auto tracking finding circuit and method of a video tape recorder that can contribute to the software servo configuration.

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

1 is a circuit diagram according to the present invention, which includes a reference ATF (1) and a 1BPF (2) and a second BPF (3) and a first and second peak detectors (4, 5) and an op amp (6). And a pilot comparison unit 10 comparing the reference pilot and the low pass filter unit 20 receiving the ATF error signal 11 of the pilot comparison unit 10 and smoothing for capstan phase control, and a PB. A buffer C1 for waveform shaping the ATF error signal 11 of the pilot comparison unit 10 to detect a mode, and an inverter C3 and end generating sampling and hold pulses to check an ATF lock. S / H pulse generating means comprising a gate C4, and an S / H portion 30 for holding data of the buffer C1 by the output signal of the S / H pulse generating means.

2 is a timing diagram according to the present invention.

3 is a flow chart according to the present invention.

Based on the above configuration, the present invention will be described in detail with reference to FIGS.

First, as shown in FIG. 1, the first and second selector signals S1 and S2, such as the waveforms 2b and c, determine the pilot signal of the reference ATF 1 as the waveform of the 2e diagram. do.

In addition, the pilot signal of the PB ATF such as the 2d diagram picked up from the tape is mixed in the parallel modulator and then passed through the first and second band pass filters (2, 3) to | f1-f2 | = | f3-f4 | = 16 KHz (fH) and | f1-f4 | = | f2-f3 | It outputs in the state of = 46KHz (3fH).

Therefore, the size of the 16KHz (fH) or 46KHz (3fH) component depends on the signal picked up from the tape, that is, the position of the head.

The output signals of the first and second BPFs 2 and 3 generate voltages through the first and second peak detectors 4 and 5 to be applied to the operational amplifier 6 and then input the two signals. In comparison, the output of the final ATF error signal 11 as shown in FIG. 2F is also determined by the pilot comparator 10.

Since the ATF error signal 11 is mixed with the ATF lock check signal, a waveform such as a second g degree waveform is applied smoothly through the low pass filter 20 for capstan phase control.

In order to obtain the same effect as the control pulse of the VHS format, the first and second selector signals S1 and S2 are included together with the same information as the control pulse on the ATF error signal 11.

After the ATF error signal 11 is waveform-formed through the buffer G1, a signal such as waveform 2h is applied to the microcomputer for detecting the mode.

Now, the first selector signal S1 is low and the HSW (Head Switching) signal is required because a sample and hold (Sample and Hold (S / H) signal) is needed to check the AFT lock in hardware. When is high, the first selector signal S1 is inverted through the inverter C3, and the inverted high signal and the high signal are inputted to the AND gate C2, and a high like a second waveform is output.

During the high signal period, the switch SW is controlled to check whether the signal in which the ATF error signal 11 is waveform-formed is high or low, and the S / H unit 30 holds this state.

At this time, if the output signal of the S / H unit 30 is high like the waveform of the second j, it is not a problem, but if it is low, it is in an unlocked state.

Therefore, inverting the second selector signal S2 in order to prevent noise from appearing results in the head moving one frame, so that locking can be performed immediately.

In addition, the same result can be obtained without using the S / H pulse generating means and the S / H unit 30 as shown in FIG. 3 to perform the above operation in software.

First, in step 1A, the microcomputer determines whether it is a PB, and performs other routines other than the PB, and performs step 2A if it is a PB.

In step (2A), the standard play (hereinafter referred to as SP) is set high and step (3A) is performed.

In step (3A), a signal obtained by waveform shaping the ATF error signal 11 is checked, and the microcomputer checks whether the signal is 30 Hz or 60 Hz.

At this time, since the initial value is set to SP, it is the 30 Hz and performs step (4A) to set the SP to high, and if it is not 30 Hz but 60 Hz, 30 Hz is set to match 30 Hz. Is called high).

After performing step (10A), in step 11A, check whether the signal for which the ATF error signal 11 is waveform-formed is 30 Hz, and perform step (12A) if it is 30 Hz. Perform step 4A.

After determining the mode as described above, to check the ATF lock status in each mode, the microcomputer determines whether the first selector signal S1 is low and the HSW signal is high in step 5A after step (4A). If not, check again, and if correct, perform step (6A).

In step (6A), it is checked whether the output signal of the S / H pulse generating means, which is the output signal of the AND gate (C2), is high or not in the ATF lock state, so in step (7A), the second selector signal (S2) is checked. Butt to perform step (5A).

The inverting immediately changes the reference ATF pilot signal so that the capstan phase control can be performed without noise on the screen.

If the output signal of the S / H pulse generating means is high, lock the ATF in step (8A) and check whether it is in PB mode in step (9A). If it is in PB mode, perform step (3A) again. Perform.

The step (12A) performs the same as the step (5A), the step (13A) is a step (6A), the step (14A) is a step (7A), the step (15A) is a step (8A), (16A) Step performs the same as step (9A).

However, in step (16A), step (10A) is performed in the PB mode.

Therefore, all necessary information is included on the ATF error signal 11 by changing the first and second selector signals S1 and S2 without using any external S / H pulses, and the information is analyzed where necessary to capture the capstan phase. All operations can be performed, including control and mode detection ATF locking.

As described above, the reference ATF pilot signal is changed to include all the necessary information on the ATF error signal, so that various operations can be performed with a single signal without a separate control signal, so that the servo can operate stably while operating conveniently. This has the advantage.

Claims (3)

In the auto tracking finding circuit of a video tape recorder having a pilot comparison unit 10, a low pass filter unit for receiving the ATF error signal 11 of the pilot comparison unit 10 and outputting it smoothly and as a servo. (20), waveform shaping means for waveform shaping and outputting the ATF error signal 11 of the pilot comparison section 10 to the microcomputer, and sampling and hold pulses by the first selector signal S1 and the HSW signal. A video tape recorder comprising: an S / H pulse generating means and an S / H portion 30 which holds the output signal of the waveform shaping means by the output signal of the S / H pulse generating means. The Advanced Auto Tracking Finding Circuit. In the auto tracking method of the video tape recorder, the SP is set in the PB mode, and the waveform of the ATF error signal 11 is set in the case of 3 Hz, the SP is set, and the LP is set in the case of 60 Hz instead of 30 Hz. A first step of resetting the SP by checking whether the shaped signal is 30 Hz or ATF if the S / H pulse generation signal is high when the first selector signal S1 is low and the HSW signal is high after the SP is set; In the PB mode, if the waveform-shaped signal is again checked at 30 Hz, and if the S / H pulse generation signal is low, the second process of inverting the second selector signal S2 is performed. If the first selector signal S1 is low and HSW is high, the S / H pulse generation signal is high, the ATF is locked, and in the PB mode, LP is set again. If the S / H pulse generation signal is low, the second selector signal ( Characterized in that the third process of inverting S2) How is Advanced Auto Tracking Video tapes Le Kou Finding more. 2. The advanced auto tracking finding circuit of a video tape recorder according to claim 1, wherein the S / H pulse generating means generates a sampling and hold pulse by performing a logical multiplication of the signal in which the first selector signal (S1) is inverted and the HSW signal.

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