JPH07111661A - Head switch phase adjusting device - Google Patents

Abstract

PURPOSE:To enable the adjustments of two systems by an adjusting work by performing a head switch phase adjustment according to the TV signal of one system and determining the phase adjusting amount for the TV signal of the other system by a calculation. CONSTITUTION:A tape for PAL adjustment is used, a vertical synchronizing signal is extracted from a composite synchronizing signal in an integration waveform fairing circuit 1 by a PG adjusting mode, a waveform fairing is performed for the signal and the signal is transmitted to a phase comparison/ error detection circuit 3. The circuit 3 compares the target phase value stored in a ROM 2 and a measured value and controls a delay pulse preparation circuit 5 so as to be the target phase value. A PG signal is inputted in the circuit 5 via an amplifier/waveform shaping circuit 4 and a delay value is controlled. When the target phase is confirmed in the circuit 3, the delay value at the time is stored in a PAL delay value memory 6. Next, an NTSC delay value is determined in a calculation circuit 7 according to the number of rotation ratio of the PAL and NTSC based on the PAL delay value. Thus, two kinds of adjusted values are obtained by an adjustment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PTR with a VTR or NTSC playback (recording) function corresponding to a plurality of types of television systems.
The present invention relates to a phase adjusting device for a head switching pulse of an AL type VTR.

[0002]

2. Description of the Related Art Television systems adopted in the world are roughly classified into two types, NTSC system and PAL system, and a VTR is made corresponding to each.

At the beginning of television broadcasting, there were no particular problems because they were used as closed systems, but when the exchange of information at the global level became active recently, information from both systems will be exchanged. The need for replacement is increasing.

Therefore, it is desired that a VTR recorded by two types of systems can be reproduced by one VTR, and a VTR which enables this has already been developed.

Although there are various technical differences between the two systems, one of the points to be solved when realizing a VTR applicable to the two systems is to adjust the head switching phase according to each system. There is a point that must be.

Such a conventional head switching phase adjusting device will be described with reference to FIGS.

FIG. 3 shows the relationship between the drum phase reference signal generator (hereinafter referred to as PG) arranged on the drum and the video head. Further, FIG. 4 shows the time relationship. There is an angle θ between the PG video heads, and this θ has a mechanical dimensional variation, and the PG phase adjustment is to electrically absorb the dimensional variation. (Adjustment of head switching timing and vertical sync phase in the VHS standard.) FIGS. 5 and 6 show a general flow of a conventional PG phase adjustment in a VTR that is compatible with the PAL system and the NTSC system.

5A to 5F are PAL system PGs.
This is work for adjusting the phase. First, a PAL standard tape (adjustment tape) is inserted into the VTR and reproduced. Then, this VTR runs in the PAL system mode. PG
The adjustment mode is set, the PG phase is adjusted, and the time T _PAL (the angle difference of θ converted into the amount of time) is obtained. Time T _PAL
The method of making is either an analog mono-multi (using a charging time constant combining a capacitor and a resistor) or a digital mono-multi using a microcomputer. And time T
_{Memorize PAL} . On the other hand, at the time of NTSC, VTR is set to N
The vehicle is run by the TSC method, and the time T _NTSC (performed in the same procedure as PAL) is obtained and stored in the flow of (g) to (l) of FIG.

[0009]

As described above, conventionally, in order to obtain the phase value for NTSC and the phase value for PAL, the same work had to be repeated. Therefore, adjustment work takes time, which is a factor of cost increase.

The present invention has been made in consideration of the above point, and provides a head switching phase adjusting device which does not require the other adjusting operation by performing only one adjusting operation. The purpose is to do.

[0011]

In order to achieve the above object, in the present invention, in a video tape recorder for recording and reproducing two types of television signals such as NTSC and PAL, a drum phase reference signal of one type is used. (PG)
Measuring / recognizing means for measuring / recognizing the phase difference from the output to the head switching pulse by digital numerical values, memory means for storing the digital numerical values, and the numerical values stored in the memory means for the television of the two systems. And a calculating means for calculating a phase adjustment value of another method according to the ratio of the vertical synchronizing frequency between the signals. A head switching phase adjusting device is provided.

[0012]

According to the present invention, the head switching phase adjustment is performed according to the television signal of one system, and the phase adjustment amount for the television signal of the other system is obtained by calculation. The adjustment for the two-system television is completed simply by performing the adjustment work.

[0013]

Embodiments of the present invention will be described below with reference to FIGS.

First, a block diagram will be described with reference to FIG. Reference numeral 1 is an integration / waveform shaping circuit for extracting a vertical sync signal from the composite sync signal, 2 is a ROM in which a target phase value is stored, and 3 is a phase comparison / error detection circuit for performing phase comparison and error detection. Further, 41 is an amplification / waveform shaping circuit for amplifying and shaping the PG signal, 5 is a delay pulse creation delay value output circuit, and 6 is a PAL delay value memory in which the delay value in the PAL mode is stored. Yes, 7 is a PAL delay value × 5 ÷ 6 calculation circuit that performs an operation according to the rotation ratio of PAL and NTSC of 25/30, and 8 is an NTSC delay value memory that stores the output value of the calculation circuit 7.

Next, the operation will be described. First, the PAL adjustment tape is used, and in the PG adjustment mode, the vertical synchronizing signal is extracted from the composite synchronizing signal by the integral waveform shaping circuit 1, and the waveform is shaped and sent to the phase comparison / error detection circuit 3. R
The measured value is compared with the target phase value (the phase difference between the vertical synchronization and the head switching pulse) stored in OM2, and the delay pulse creation block is controlled so that the target phase value is reached.

In order to detect the rotation phase of the drum, the delay pulse generating circuit 5 receives the PG signal after the waveform is shaped by the amplifying / wave shaping circuit 4, and the delayed pulse (head switching pulse) is input from the PG. Pulse value) is controlled.

When it is confirmed by the phase comparison / error detection circuit 3 that the target phase has been reached, the phases of the PG and the delay pulse at that time, that is, the delay value, is regarded as the PAL delay value.
It is stored in the PAL delay value memory 6.

Next, based on the PAL delay value, a value of about 83% is calculated by the (PAL delay value) × 5 ÷ 6 calculation circuit 7 according to the rotation speed ratio of 25/30 between PAL and NTSC. To do. That value is the NTSC delay value, NT
It is stored in the SC delay value memory 8.

Two speeds (in this case PAL 25H
z, NTSC 30Hz) even if there is a difference, mechanical error (θ ± α shown in FIG. 3) can be adjusted only once.
Two kinds of adjustment values can be obtained.

FIG. 2 shows a flowchart of the embodiment.

First, PAL standard tape (adjustment value tape)
Is inserted into the VTR and the PLAY mode is set. The VTR body is run at PAL. The digital mono-multi is used as the PAL PG phase adjustment mode, and the digital mono-multi is adjusted to absorb the mechanical mounting error θ ± α. The numerical value T _PAL is _stored as the PAL PG phase adjustment value.

Next, on the _basis of T _PAL , 25
Perform a calculation of / 30≈83%.

T _PAL × 83% = T _NTSC , NTSC
Memory is stored as the PG phase adjustment value.

[0024]

According to the present invention, it is possible to adjust the NTSC system and the PAL system each by one adjustment.
As a result, significant improvements can be made in terms of accuracy and labor.

[Brief description of drawings]

FIG. 1 is a block diagram of the present invention.

FIG. 2 is a flowchart of the present invention.

FIG. 3 is a head layout diagram on a drum according to the present invention.

FIG. 4 is a timing diagram of a head switching pulse for a PG according to the present invention.

FIG. 5 is a flowchart when adjusting a PAL system according to a conventional technique.

FIG. 6 is a flowchart at the time of adjusting the NTSC system of the related art.

[Explanation of symbols]

 1 Integral waveform shaping circuit 2 ROM 3 Phase comparison error detection circuit 4 Amplification / waveform shaping circuit 5 Delay pulse creation circuit 6 PAL delay value memory 7 PAL delay value calculation circuit 8 NTSC delay value memory

Claims (1)

[Claims] 1. A video tape recorder for recording and reproducing television signals of two systems such as NTSC and PAL, the digital phase difference from the drum phase reference signal (PG) of one system to the head switching pulse output. Measurement
Measuring / recognizing means for recognizing, memory means for memorizing the digital numerical value, numerical values memorized in the memory means are calculated according to a ratio of vertical synchronizing frequencies between the two types of television signals, and another method. And a calculation means for obtaining the phase adjustment value of the head switching phase adjustment device.