JPS60223274A - Automatic tracking device of vtr - Google Patents

Abstract

PURPOSE:To attain accurately the tracking in a slow reproduction mode by deciding the control timing of a capstan motor by the reproduction output difference between the trace start and end parts of a rotary head in a still reproduction mode. CONSTITUTION:When a slow reproduction button is operated, the intermittent control pulses are supplied from an input terminal 7. Then the head switch pulse of a terminal 6 is supplied intermittently to a capstan motor 13 from an OR gate 12 as a start pluse. Thus the motor 13 is started to drive a tape, and the reproduction control pulse is produced. Then a brake pulse is produced from a monostable multivibrator 10 and sent to the motor 13 through the gate 12. The time width of the vibrator 10 is controlled by the output of a comparator 31 which obtains the reproduction output difference between the head trace start and end parts. In such a way the accurate tracking is executed.

Description

Detailed Description of the Invention Field of the Invention The present invention relates to an automatic tracking device for a VTRVC capable of intermittent slow playback.

(b) Conventional technology field still reproduction? A rotating head switching signal (RF switch pulse) and a playback control pulse (
CTL) controls the starting and braking of the capstan motor that allows the rotating head to optimally trace the recording track. In FIG. 5, (a) is a track pattern diagram showing a head trace during intermittent slow playback, with the horizontal axis representing time and the vertical axis representing head travel distance. Conventionally, (RF SW-Sochi pulse and CQ shown in bJ)
The brake pulse shown in (e) was applied to the capstan motor at the falling timing of (d) from the regeneration control pulse shown in ) to perform intermittent driving.

Here, a problem arises regarding tracking during intermittent slow playback.

During intermittent slow playback, the time from control pulse playback to brake pulse generation is made variable.
At that time, the tiger installed on the i5V TR body
Adjustments have been made using the tracking volume to deal with compatibility, Fi changes over time, and temperature changes, but especially against changes over time in the tape drive mechanism, it is necessary to compensate for the tracking amount that is set once and maintains the optimal state forever. This was inconvenient as it required frequent adjustments. For this reason, Japanese Patent Laid-Open No. 57-206182 proposes automatic tracking to optimize slow playback.

However, in this known method, the pulse width of the pulse generated in synchronization with the playback control signal is adjusted to the same level as the pulse indicating that the playback envelope of the rotary head has fallen below a certain level and the head switching pulse when the tape is stopped. The timing is changed according to the phase difference, and the brake is started at the falling edge of this pulse whose width is controlled. Therefore, only the information on the lower limit side of the regeneration envelope of rotation and end is involved in the timing of the brake. Therefore, if the information on the lower limit side is not accurate due to errors in the recording track or a straight line, controlling the brake timing entirely using the information when the lower limit falls below a certain level will reduce noise. I have to say that it is inferior in terms of achieving the goal of not producing waste.

Moreover, in the known example, the entire circuit for forming the sawtooth wave is required to be long before performing a phase comparison between the pulse indicating that the reproduction envelope has become below a certain level and the head sweeping I pulse, which is undesirable in terms of circuit configuration. .

EL OBJECTS OF THE INVENTION An object of the present invention is to propose an automatic tracking device for a VTR that can accurately track tracking during slow playback with a simple configuration.

B) Structure of the Invention The present invention provides a VTR capable of performing intermittent slow playback by alternately repeating standard mode playback and still mode playback during playback, in which the trace start portion of the rotary head and the trace during still mode playback are provided. This automatic tracking device for a VTR has a detection means for detecting a reproduction output difference at the end portion, and a means for completely determining the braking timing of a capstan motor based on the output of the detection means.

Example of a solid cannon In FIG.
Five bases (a) (bl (c)) with different positions of the head trace +21 indicated by the dashed line from B) lead to rotation.!
Focusing on the fact that the playback envelopes of these two envelopes are different, as shown in Figure 4, (C), we use the output difference between the rotary head trace start part (31) and end part (4) of the envelopes to find the optimal Kamo-sama (b). The purpose is to fully control the cab stan motor so that Ic.In Fig. 4, (R
FSW) indicates the head 9 calling pulse.

FIG. 1 is a circuit diagram of a traffking device embodying the present invention, in which reference numeral 1101 denotes a first mono-multivibrator that generates a pulse in synchronization with the reproduction control pulse (a) applied to the first input terminal 151; Ill is a second mono multivibrator that generates a brake pulse of a certain time width in synchronization with the fall of the leg output pulse (b) of the first mono multivibrator 11.This output is sent to the capstan through OR gate I+21. is applied to the motor 1131. (14) masks the rotation switching pulse (d) applied from the second input terminal (61) according to the intermittent control signal applied via the third input terminal (7), and This is a gate that allows only one rotary head switching pulse to pass in each period, and the intermittent control signal is formed based on a signal given from a system control circuit (not shown) during slow playback mode (151 is the above-mentioned gate). This is the fifth monomultipipe rake that is generated in synchronization with the fall of the rotational switching pulse that has passed through the gate (e), and the mark a is a pulse with a constant time width that is synchronized with the fall of the pulse (e). Start pulse (to) t - This is the fourth mono multivibrator that generates.This start pulse (to)
is OR game) 11 A and capstan motor (131
The circuit of 0 or more added to is also provided in the conventional slow playback trafficking circuit. σn is head switching from the second input terminal +e+)
Two powers (chi) are added to the first AND gate Tsumugi. (18
1, a pulse obtained by inverting the output of the second mono multivibrator 0υ with an inverter ■ is given as a set signal,
The third mono multivibrator (151 is an R-8 flip-flop whose output is given as a reset signal,
As shown in Figure 2 (N), the output is low level in standard mode playback, and the still playback upper terminal (61 head switching pulse (D) is the fifth mono multivibrator [21]).
and 4 to the sixth monomultiviprator 423 via the inverter +nt. The outputs of the fifth and sixth mono multivibrator 12D are OR game) +
The output of the OR gate 1'241 is inverted by the inverter G and supplied to the second AND gate 1201 as shown in Figure 2. The regenerated output of the rotary field given from the input terminal 4 (8) is detected by the detector I2 mark, and the output pulse (Le) Fi
As shown in FIG.
These outputs are compared by a comparator 1311, and the comparison output is sent to the first mono multivibrator 1.
It is given to vary the time constant of lllll c34
is a switching circuit that switches the rotation direction of the capstan motor 1131, and is normally determined by a signal given from the fifth input terminal (91).

The signal at the fifth input terminal (91) is given from the system control circuit, and exhibits a low level (the capstan is rotated in the reverse direction 7j) during reverse playback, reverse search, and short rewind at the time of succession. Other than that, it exhibits a high level (rotating the carburetor tongue in the forward direction).However, in addition to that, when braking due to still regeneration, the brake pulse (c) given from the second multi-biflator all Since the output of the switching circuit C) is forcibly set to a low level, the capstan motor is driven by VC in the opposite direction during braking.

Next, the operation shown in FIG. 41 will be explained with reference to FIG.

First, when the slow playback button installed on the VTRvc is operated, the system control circuit operates to generate a field switching pulse (second input terminal 16) at the 43 input terminal (an intermittent control pulse is given from 71, so the second input terminal 16). ) can only pass through the gate intermittently, and the falling edge of the head switching pulse that has completely passed there Q VC, Q L fc
The pulse (e) is passed from the third mono multivibrator (13) to the second monovibrator (as shown in Fig. 2) at regular intervals. It is added to the capstan motor (131), which starts and rotates the capstan.

Since the tape is transferred in accordance with the rotation of the capstan (13), a playback control pulse (in) is generated as shown in FIG. ] A pulse (B) is generated, and this pulse (brake pulse (C) with a fixed time width in synchronization with the falling edge of J) is generated from the second monomultivibrator (lυ) and brakes the capstan motor T At this time, the brake pulse (c) is switched to the switching circuit C.
321 is applied to the switching circuit c32 and remains at a low level only during the output brake pulse period. Therefore, when the brake is operated, the capstan motor (13) is driven in the opposite direction to produce an effective 11! signal. ) occurrence timing is g1 mono multivibrator 1lt.
This can be controlled by controlling the time constant of li and changing the output pulse (b) of the @1 mono multivibrator 1101 to a pulse l11M'. Control of this pulse width is performed as follows. In response to the falling of the brake pulse (1) generated from the @2 mono multivibrator dυ, the R87 rifling flow is in a state like that. In response to the head switching pulse (2) from the 42 input terminal (6; The sampling pulse is applied as a sampling pulse to a suitable 4-A bar.Meanwhile, the head switching pulse (2) is also formed from the head switching pulse (2) and the head l/J
m, t end part of pulse, i.e. L/- end part +4
A pulse circuit (28) with an appropriate width corresponding to 1
1 as a sampling pulse. Therefore, the first sampling circuit (27) samples the gutter reproduction output at the head trace start part (31), and the second sampling circuit (28) samples the throat reproduction output at the head trace end part (4).
Sample the head playback output.

These sampled playback outputs are transferred to the hold circuit [
291+ force, respectively, and are compared by a comparator 1311.

In the still playback mode, if an undesired trace pattern such as 5th < Q J occurs, as can be seen from FIG. The output of the comparator 1311 becomes a high level, which reduces the time constant of the first mono-multivibrator tlol (thereby narrowing its output pulse width).By doing this, the timing at which the brake is applied becomes earlier, as shown in Fig. 61 (b). ).Inverse VC Figure 3 (a
), 1/i: is the fourth
As can be seen from figure (a), the reproduced output of the ending part (4) is larger than the reproduced output of the starting part +31, so the comparator θ
The output of step 1) becomes low level and becomes the time constant of the first mono-multivibrator.

(F) Effects of the Invention According to the present invention, in a VTR that performs slow playback by repeating the standard playback mode and the still playback mode, the timer/fukinder in the still playback mode is automatically set to an optimal state, which is excellent. This has the effect that slow playback images can be obtained. In addition, in the present invention, since the control signal for automatic tracking is obtained by detecting the playback output difference between the head trace start part and end part in the all-still playback mode, an accurate control signal can be obtained with certainty. Another effect is that automatic tracking can be achieved.

A further advantage is that there is no need to use a sawtooth wave generation circuit for forming control signals.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an automatic tracking device based on the present invention, FIG. 2 is a waveform diagram of each part of FIG. 1, and FIGS. 6 and 4 are explanatory diagrams thereof. FIG. 5 is a diagram for explaining the entire conventional example. (3t...Trace start part, (4+...Trace end part, (101...First mono multivibrator, (control timing? means for determining), f+, 31...
Cab stan motor, t311... Comparator (means for detecting difference in reproduction output) Q Applicant Sanyo Electric Co., Ltd. Agent Shizuo Sano Figure 1 Figure 3

Claims (1)

[Claims] 11+ In a VTRvc capable of performing intermittent slow playback by alternately repeating standard mode playback and still mode playback during playback, the playback output difference between the trace start part and the trace end part of the rotary head during still mode playback is determined. What is the braking timing of the capstan motor based on the detection means to detect and the output of the detection means? Automatic tracking Ha of a VTR with means for determining.