JPH01149202A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To set an optimum recording current characteristic to both signals by separately switching and controlling the recording current characteristic of the respective signals when a video signal, which is FM-modulated in the recording track of one revolving head, and a sound signal to be PCM-modulated are recorded in time-division. CONSTITUTION:A switch 14 to be connected to the input of a record amplifier 13 is a switch to change-over the FM-modulated video signal and the PCM- modulated sound signal in the time division. Then, the FM-modulated video signal is connected to an input terminal 14a and the PCM-modulated sound signal is connected to an input terminal 14b. The switch 14 and a switch 15 are simultaneously changed-over to the time-dividing input terminal of input terminals 14d and 15d by a time-dividing switch control signal 18 respectively at a time to correspond to a track position on a tape. Thus, the recording current characteristic, which flows to a head 9 to be connected to the output terminal of the recording amplifier 13, can be caused to be optimum respectively in both signals of the FM-modulated video signal and the PCM-modulated sound signal.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a magnetic recording/reproducing device such as a VTR.

(Prior Art) Video tape recorders (VTRs) and the like are well known as magnetic recording and reproducing devices for recording and reproducing video signals.

Conventionally, when recording video and audio signals on a VTR, the common method is to record the video signal using a rotating head after FM modulation, and to record the audio signal using a fixed head on a track in the longitudinal direction of the tape, using a bias recording method. there were.

In recent years, with the same tape length (same size tape cassette),
VTRs that enable longer recording and playback times have been put into practical use.

Since these VTRs record for a long time, the tape feed speed is slowed down. However, compared to video signals recorded with a rotating head, the characteristic deterioration of audio signals recorded on longitudinal tracks with a fixed head has become a problem.

Therefore, there are methods in which the audio signal is FM modulated and frequency-multiplexed with the video signal and recorded using the same head, or the head for the video signal is recorded using a separate rotating head.The audio signal also rotates in the same way as the video signal. Various methods of recording with a head have been devised, some of which have been put into practical use, and attempts have been made to improve the characteristics of audio signals.

Furthermore, in recent years, a method of binary encoding (PCM) audio codes and recording them as digital signals has come into practical use.

The PCM recording method has attracted attention as a method that causes almost no deterioration in sound quality compared to conventional analog recording methods, and has been commercialized in the form of compact discs and DAT.

With regard to VTRs, there is also a strong demand for higher quality audio, and several methods have been devised in which a PCM modulated audio signal is time-divisionally recorded using the same rotating head as an FM modulated video signal.

Figure 3 shows the track pattern on the tape according to the above, and (a) is the position where part 1 where the PCM modulated audio signal is recorded is temporally delayed from part 2 where the FM modulated video signal is recorded. This is the track pattern recorded on . (b) is 1 recorded between 2, (
In C), 1 is recorded first, and then 2 is recorded later.

In either case, the same head is used to record the video signal and the audio signal, so the recording amplifier conventionally used for these recordings has generally been of the type shown in FIG.

In FIG. 4, the switches 5a and 5b connected to the input terminal 4 of the recording amplifier 3 switch the FM-modulated video signal and the PCM-modulated audio signal at a time corresponding to their recording position, so that they become one signal. This becomes a time-division recording signal.

A trimmer 6 attached to the recording amplifier 3 changes the characteristics of the recording current flowing to the head 7 connected to the output of the recording amplifier 3.

In this manner, the conventional recording circuit provides the same recording current characteristics for FM modulated video signals and PCM modulated audio signals. Generally, the recording current characteristic that is optimal at the carrier center frequency of the FM modulated wave is selected, and at this time the S/N of the video signal after FM demodulation is the best. As a result of the experiment, the recording current characteristics at this time are as follows.
The recording current was not optimal for a PCM modulated audio signal, and the error rate when PCM demodulated was not the best.

(Problems to be Solved by the Invention) As described above, when recording an FM-modulated video signal and a PCM-modulated audio signal in the same head in a time-division manner, the recording current characteristics are different from those of the conventional example. If they were made the same, there was a problem that even if one of them was adjusted to the optimum current characteristic, the other would not have the optimum current characteristic.

[Structure of the invention]

(Means for Solving the Problems) The present invention was devised to solve the above-mentioned problems, and the present invention combines an FM-modulated video signal and a PCM-modulated video signal during the recording trajectory of one rotary head. An object of the present invention is to provide a magnetic recording/reproducing device that can provide optimal recording current characteristics to each signal when recording audio signals in a time-division manner.

(Function) In the present invention, the first recording current control means determines the recording current characteristics of the F'M modulated video signal, and the second recording current control means determines the recording current characteristics of the PCM modulated audio signal. control means, and by each recording current means,
By separately switching and controlling the recording current characteristics of each signal recorded in time division, it is possible to set the optimal recording current characteristics for both signals.

(Example) An embodiment of the present invention will be described with reference to FIG.

FIG. 1 is a diagram showing a rotating drum section of a two-head helical scan VTR. 8 in the same figure is a rotating drum, 9a and 9
b is a video head installed on the rotating drum 8, and 1
0 represents magnetic tape. The magnetic tape 10 is wound around the rotating drum a little more than 180 degrees (approximately 30 degrees), and is configured to record a PCM-modulated audio signal in this overlap angle range 11. There is.

A 180' angle range 12 shown in FIG. 1 is a portion where an FM modulated video signal is recorded.

The track on the tape at this time becomes a recording locus corresponding to FIG. 3(a).

FIG. 2 is a diagram showing a portion of a recording current amplifier for supplying recording current to the video heads 9a and 9b of FIG. 1. (Only one head is shown to simplify Wi-Fi.) A switch 14 connected to the input of the recording amplifier 13 is a switch for time-divisionally switching between an FM-modulated video signal and a PCM-modulated audio signal. , 14a are connected to an FM modulated video signal, and 14b are connected to a PCM modulated audio signal.

The switch 14 and the switch 15 are each 14d.

A time division switching control signal 18 is sent to a time division input terminal 15d so that switching can be performed simultaneously at times corresponding to track positions on the tape.

With this configuration, the characteristics of the recording current flowing through the head 9 connected to the output terminal of the recording amplifier 13 can be optimized for both the FM modulated video signal and the PCM modulated audio signal. It becomes possible to do so.

〔Effect of the invention〕

In a device that time-divisionally records and reproduces an FM-modulated video signal and a PCM-modulated audio signal during the recording trajectory of a rotating head, it is possible to set the recording current optimally for both. Modulated video signal and PC
By controlling switching separately for M-modulated audio signals, it is possible to achieve the best S/N after demodulating FM-modulated video signals and the total error rate after demodulating PCM-modulated audio signals. It has the effect of

[Brief explanation of the drawing]

FIG. 1 is a layout diagram of an embodiment of the rotating drum section of a two-head helical scan VTR of the magnetic recording and reproducing apparatus of the present invention;
FIG. 2 is a block diagram of one embodiment of the recording amplifier of the present invention, relating to time-division switching control of an FM-modulated video signal and a PCM-modulated audio signal, and respective recording current controls;
The figure shows a time-division recording pattern on a magnetic tape, and FIG. 4 is a block diagram of a conventional recording amplifier, relating to modulated signals, time-division switching, and recording current control. Description of symbols 1...Track pattern of PCM modulated audio signal 2...Track pattern of FM modulated video signal...Recording amplifier (conventional) 4...Input terminals 5a, 5b...Switch 6... Trimmer 7... Head 8... Rotating drum 9... Heads 9a, 9b... Head 10... Magnetic tape 11... 30° angle 12... 180° angle 13. ...Recording amplifier (present invention) 14...Switch (time division switching) 14a...FM modulated video signal input terminal 14b
... PCM modulated audio signal input terminal 14d...
Time division input terminal 15...Switch (current characteristic switching) 15a...FM modulation current control input terminal 15b...P
CM modulation current control input terminal 15c... Recording amplifier current control input terminal 15d... Time division input terminal 16... FM modulation current control trimmer 17... PCM modulation current control trimmer 18... Time division switching control Signal Agent Patent Attorney Noriyuki Ken Yudo Mitsuyuki Matsuyama Figure 1 Figure 3

Claims (1)

[Claims] In a magnetic recording/reproducing device in which an FM-modulated video signal and a PCM-modulated audio signal are time-divisionally recorded during a recording trajectory formed by a rotating head, recording of an FM-modulated video signal is performed. 1. A magnetic recording/reproducing apparatus comprising a first recording current control means for determining current characteristics and a second recording current control means for determining recording current characteristics for a PCM-modulated audio signal.