JPH0542751B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a tracking control circuit in a dubbing system.

(b) Prior art Regarding a dubbing system that performs dubbing using two VTRs, for example, see the July 1982 issue No. 46 to 53 of the magazine "Television Technology" published by Denshi Gijutsu Publishing.
It is also introduced on the page.

This dubbing system aims to improve recording characteristics by supplying color components and luminance components separately to the recording VTR.

(c) Problems to be Solved by the Invention However, in the above-mentioned dubbing system, the playback side VCR may be damaged due to the user's carelessness during dubbing.
When you operate the tracking volume, an unstable screen with changed tracking status may appear on the recording side.
It will be recorded on a VCR.

Therefore, the present invention proposes a tracking control circuit that is not affected by tracking adjustment by limiting the tracking adjustment of the reproducing VTR during the dubbing period.

(d) Means for Solving the Problems The present invention is a tracking control circuit that disables tracking adjustment when the recording VTR is in recording mode, and enables tracking adjustment when the recording VTR is in recording pause mode. be.

(E) Effect Therefore, tracking adjustment is possible when the recording side VTR is in standby mode, and once the tape starts running and recording starts, tracking adjustment is invalidated from then on, so tracking adjustment cannot be performed during recording. Therefore, a distorted screen will not be recorded.

(f) Examples The present invention will be described below with reference to illustrative examples.

First, the first embodiment, which is not shown in FIG. 1, is one in which the present invention is applied to a dubbing VTR that integrates two VTRs of different systems, and the figure only shows the servo circuit of the playback VTR. ing.

In the VTR of this embodiment, the rotation of the head motor 1 is detected by the first rotation detection means 2, and the rotation detection output is inputted to the first AFC circuit 3.
It is input to the comparison side input terminal of circuit 4. Said No.
A fixed reference signal (30Hz) selected by the first RP switch S1 is connected to the reference input terminal of the 1APC circuit 4.
is input. Therefore, the first AFC output and the first APC
When the added output obtained by inputting the output to the adder circuit 5 is input to the head motor 1, the rotation of the head motor 1 is phase-locked to the reference signal. On the other hand, the rotation of the capstan motor 6 is
The rotation detection means 7 detects the rotation, and its rotation detection output is input to the second AFC circuit 8. On the other hand, the playback control signal derived from the control head CH is input to the digital delay circuit 9 via the second RP switch S2 for tracking, and is then sent to the comparison input of the second APC circuit 10 via the third RP switch RP. Supplied to the terminal. Said No.
A reference signal is input to the reference input terminal of the 2APC circuit 10, and when the second APC output and the second AFC output are added in the adder circuit 11 and input to the capstan motor 6, the The capstan motor 6 is phase locked to the reference signal. The frequency dividing circuit 12 in the figure is a circuit that divides the rotation detection output of the capstan motor 6 into a frame period (30 Hz) and derives a comparison signal during recording.

This embodiment is characterized by the following points. The amount of delay of the digital delay circuit 9 is defined by the read data of the voltage memory 13. This voltage memory 13 always derives read data, and as long as the write inhibit signal is generated, the AD
Conversion data is repeatedly written in conjunction with AD conversion operation. This AD conversion data is obtained by inputting a set voltage value set by the tracking volume 14 to the AD conversion circuit 15.

The aforementioned write inhibit signal is at a high level only when the recording side VTR is in the recording mode in the dubbing mode, and inhibits writing of AD conversion data. Therefore, this write inhibit signal is generated by the logical product of the dubbing mode setting signal, which becomes high level when both VTRs are set to dubbing mode, and the inverted signal of the pause mode signal, which becomes high level when set to recording pause mode. derived.

Therefore, in this embodiment, the recording side is
When the VTR is in recording mode, the amount of tracking delay is fixed, and the recording side
When the VTR is in recording pause mode, the amount of tracking delay can be varied.

However, in the embodiment described above, tracking adjustment is disabled when the recording side VTR is in recording mode, and although there is no risk that an unstable screen will be recorded due to tracking adjustment, once recording pause mode is set, Tracking is performed according to the set position of the tracking volume.

Therefore, in the second embodiment shown in FIG. 2, the inconvenience caused by the tracking adjustment made by the recording side VTR during the recording mode setting period is prevented from remaining after the recording pause mode is set. That is, in this embodiment, an up-down counter 16 is provided in place of the voltage memory 13, and this up-down counter 1
The output of the oscillation circuit 17 is selectively supplied to the two inputs of the oscillation circuit 17. This selection is made by the tracking switch 18 during tracking adjustment, and the count value of the up-down counter is controlled by tilting the section biased to the intermediate position to either side. In the above configuration, the gate circuit 19 disposed between the tracking switch 18 and the oscillation circuit 17 receives the write inhibit signal as a control input, and as long as the recording side VTR is in the recording mode, the gate circuit 19 is disposed between the tracking switch 18 and the oscillation circuit 17. The count value of the down counter 16 does not change, and there is no possibility that the recording side VTR will be affected by operating the tracking switch 18 during the recording mode setting period when the pause mode is set.

(G) Effects of the Invention Therefore, according to the present invention, the tracking adjustment of the reproducing VTR is disabled during the dubbing mode setting period and the recording VTR is disabled during the recording mode setting period,
This is very effective because the recording side VTR does not record the unstable and moving noise caused by tracking adjustment.

[Brief explanation of the drawing]

FIG. 1 shows a servo circuit block diagram according to a first embodiment of the present invention, and FIG. 2 shows a circuit block diagram of a tracking adjustment circuit according to a second embodiment. 9... Digital delay circuit, 14... Tracking volume, 13... Voltage memory, 18...
Tracking switch.

Claims (1)

[Claims] 1. A playback VTR that manually sets a delay time and performs tracking control according to the set delay time, and a recording VTR that records the playback output of the playback VTR. In the dubbing system, the manual operation is disabled during the recording mode setting period of the recording side VTR, and the delay time can be set by the manual operation during the recording pause mode setting period of the recording side VTR. control circuit.