JPH01235056A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain the best tracking state by adding a signal delay means to a record and reproduction signal line for the control signal and changing the delay value of a signal delay means in accordance with plural types of recording time modes for change of the timing of the control signal. CONSTITUTION:A signal delay means 22 is added to a record and reproduction signal line for the control signal and the delay value of the means 22 is changed in accordance with plural types of recording time modes for change of the timing of the control signal. Therefore the picture/sound quality balance can be kept in the best state in a long time (EP) mode where a problem is posed in particular by changing the control signal recording timing of the EP mode based on that of a standard mode. As a result, the best tracking state is secured in good balance and in any one of plural time modes.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a helical scan type magnetic recording/reproducing device having multiple types of recording time modes.

[Conventional technology]

In a magnetic recording and reproducing apparatus (hereinafter referred to as a VTR), video signals are recorded on a magnetic tape using a helical scan method using a rotating magnetic head (hereinafter simply referred to as a rotary head), and are reproduced. Tracking of this rotary head requires a means for recording and reproducing control signals using a control signal recording/reproducing magnetic head (control head) provided separately from the rotary head in the longitudinal direction of the magnetic tape, and a cylinder of the rotary head. This is done using a servo system consisting of a frequency generating means (FC) attached to a motor that drives the motor, and means for controlling the motor drive signal using signals from the frequency generating means (FG) attached to the capsun drive motor.

In addition, related to this type of device is "Introduction to Home VTR" published by Corona Publishing Co., Ltd. (first edition in 1981), No. 141.
The descriptions on pages 142 to 142 can be mentioned.

[Problem to be solved by the invention]

The operation of the servo method of the above-mentioned conventional technology is in the recording time mode (
Standard mode? SP, long-term mode: EP) are exactly the same even if they are different, and each circuit constant is adjusted to maintain compatibility between each set in SP mode. This has been achieved by maintaining the correct mechanical position of the head.

On the other hand, in recent years, audio signals have come to be deeply recorded as FM signals, and a dedicated rotating magnetic head for this purpose is attached to the cylinder. Furthermore, in the future, audio signals will be converted to PCM.
If signals are to be recorded using a rotating magnetic head as well, it is conceivable that a dedicated rotating magnetic head for this purpose may also be attached.

In this way, when there are various types of rotating magnetic heads such as SP mode video heads, EP mode video heads, deep recording audio heads, etc., it is extremely difficult to keep all the heads in the correct position. It is difficult to maintain the best tracking conditions in both SP and EP modes.

In other words, differences in the relative mounting angles of the video and audio heads cause differences in the relative positions of the recording tracks drawn by the two heads, so in order to maintain compatibility between devices in both modes, it is necessary to Very strict production conditions are required.

In the case of the above-mentioned deep recording method, assuming that both heads have one ideal relative mounting angle, 'SP, E
Although the relative positional relationship of the recording tracks in both P modes is defined, the degree of freedom in design regarding the head mounting position is severely restricted.

If each video head for SP mode and EP mode is a double azimuth head, if the relative mounting angles of both the video and audio heads are arbitrarily selected, SP, E
In either mode P, the recording track relative position standard can be satisfied by selecting the control head position and the relative number of both heads by selecting a step, but under these conditions it is not possible to satisfy the standards for other modes. become unable.

As mentioned above, when there are many types of heads and multiple types of recording time modes, it is not only difficult to install all the heads in the correct position, but also to ensure compatibility. When trying to meet the standards,
The number of constraints increases, the degree of freedom in design decreases, and manufacturing becomes difficult.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic recording/reproducing apparatus that solves the problems of the prior art described above and can obtain the best balanced tracking state in any of a plurality of time modes.

[Means to solve the problem]

The above object is achieved by providing a signal delay means in the recording/reproducing signal path of the control signal, and changing the delay amount of the signal delay means according to the plurality of recording time modes to change the timing of the control signal. This is achieved by configuring the system to obtain the best tracking condition.

[Effect]

In a VTR having multiple types of recording time modes, for example, a VTR equipped with an SP mode and an EP mode,
The balance between image quality and sound quality in the EP mode, which is particularly problematic, can be kept in the best condition by changing the control signal recording timing in the EP mode using the control signal recording timing in the SP mode as a reference.

〔Example〕

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

FIG. 1 is a circuit block diagram illustrating an embodiment of a VTR according to the present invention, and shows a case in which the present invention is applied to a home VTR having two recording time modes: SP mode and EP mode.

In the figure, l is a magnetic tape, and capstan 5
It is driven to travel by. The capstan 5 is rotationally driven by a directly connected capstan motor 6.

2 is a cylinder containing a rotating magnetic head, and the rotating magnetic head is rotationally driven by a directly connected cylinder motor 3. The cylinder motor 3 also has an F for detecting the rotational speed.
Built-in G (frequency generator). Further, a tack head 4 is attached to the cylinder 2 to detect the rotational phase of the cylinder.

During recording, a vertical synchronization signal (Vsync) synchronously separated from the recorded video signal is input to the servo circuit from the input terminal 8. The input vertical synchronization signal is frequency-divided by a 1/2 frequency divider circuit 9 and input to a cylinder phase control circuit 10. A tack head output signal is input to the cylinder phase control circuit 10 , this signal and the output signal of the frequency dividing circuit 9 are phase-compared, and the comparison output is supplied to the adding circuit 11 . Further, the output signal of the FC provided in the cylinder motor 3 is input to the cylinder speed control circuit 12, and the comparison output with the reference speed is supplied to the addition circuit 11. The output of the adder circuit 11 is supplied to a motor drive circuit (not shown) to drive the cylinder motor 3.

On the other hand, the output of the crystal oscillator 13 is frequency-divided by a 30 Hz signal generator 14 to become a 30 Hz signal, which is supplied to a capstan phase control circuit 16. Further, the output of the FC provided in the capstan motor 6 is frequency-divided by frequency dividing circuits 19 and 24 according to the SPP mode and EPP mode.
This becomes a 0Hz signal and is supplied to the capstan phase control circuit 16. With this capstan phase control circuit 16, both 30
The phases of the Hz signals are compared, and the phase difference output is supplied to the adder circuit 20. Similarly to the cylinder, in the capstan, the difference between the rotational speed obtained from the FG output of the capstan motor control circuit 21 and the reference speed is determined by the capstan speed control circuit 21, and the difference is supplied to the addition circuit 20. The output of the adder circuit 20 is supplied to a capstan motor drive circuit (not shown), and the capstan motor 6 is driven.

Furthermore, in the BP mode, the output of the 1/2 frequency divider circuit 9 is delayed by the delay circuit 22 of the present invention, and is then input to a control signal recording amplifier (not shown), and is magnetically recorded by the control head (CTL head) 7. A control signal is recorded on tape 1. In the SP mode, the switch 23 is set to the SP side, and the delay circuit 22 is no longer used. Determination of the delay amount of the delay circuit 22 will be described later.

At the time of reproduction, the operation is the same as at the time of recording, except that the output of the reference 30 Hz generator 14 is selected by the switch 15 instead of the output of the 1/2 frequency divider 9 in the multi-linda servo. In the capstan servo, the control signal reproduced from the control head 7 is used as the input of the capstan phase control circuit 6 instead of the output of the frequency dividing circuit 19.24, and the output of the reference 30 Hz generator 14 is compared to Although not shown, the reproduced signal from the control head 7 is amplified by a control signal amplifier, delayed by a delay circuit 22 in the EPP mode, and supplied to the capstan phase control circuit 16 by switches 17 and 18. In SPP mode, delay circuit 22
The signal is supplied to the capstan phase control circuit 16 without passing through the capstan phase control circuit.

As is clear from the above description, the servo circuit shown in FIG. Mode EPP mode is done differently.

Next, the delay time of the delay circuit 22 will be explained. First, the cylinder phase control circuit constant is adjusted so that the vertical synchronization of the reproduced video signal matches the phase of the reproduction control signal under the SP mode self-reproduction condition. And S
Play back the PP mode semi-tape and adjust the control head position (so-called X value adjustment) to obtain the best tracking. These are normal adjustments.

Next, the EPP mode standard tape is played back, the reproduced image quality and sound quality are evaluated, and the amount of delay of the delay circuit 22 is adjusted so that the overall image quality and sound quality are in the best condition.

As described above, in this embodiment, adjustments are made to correctly reproduce standard tapes even in the EPP mode, so it is possible to improve compatible reproduction image quality and sound quality.

Also, regarding the compatibility of recording tapes recorded with this device,
Since the same delay is applied to the control signal during recording as during playback, it is possible to maintain the same X value as standard tape.

Although the means for virtually adjusting the head position has been described above, it is clear that the present invention can also be applied to a case where the head position is shifted by a certain value in advance. In this case, the delay time of the delay circuit may be set to a constant value rather than variable.

〔Effect of the invention〕

As explained above, according to the present invention, the best tracking state in each mode can be obtained by virtually shifting the head position of a VTR having multiple time modes with simple additional circuitry and adjustment. It is possible to provide a magnetic recording/reproducing device with excellent functionality by eliminating the drawbacks of the prior art.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram showing an embodiment of a magnetic recording/reproducing apparatus according to the present invention. 1...Magnetic tape, 2...Cylinder,
3...Cylinder motor FG, 4...Tack head, 6...Capstan motor FG,
7... Control head, 10...
Cylinder phase control circuit, 16... Capstan phase control circuit, 22... Delay circuit, 23...
···switch.

Claims (1)

[Claims] 1. In a helical scan type magnetic recording/reproducing device that has multiple types of recording time modes and performs tracking control of a rotary head using control signals recorded in the longitudinal direction of a magnetic tape, the recording/reproducing signal of the control signal is A signal delay means is provided in the recording time path, and the timing of the control signal is changed by changing the amount of delay of the signal delay means according to the plurality of types of recording time modes, thereby obtaining the best tracking state. A magnetic recording/reproducing device characterized by: