JPS6394467A - Multiple magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain the optimum recording regardless of a head and a tape without being influenced by a secular change by recording a luminance signal with a recording current to change to a step shape with a prescribed timing and storing a corresponding reproducing level into a memory. CONSTITUTION:Through a microcomputer part 30 of a recording current control circuit 23, switches 15a and 15b are connected to a contact (b) and the signal for testing of a luminance signal from an adjusting signal generating circuit 33 is removed. The signal comes to be a recording current to change to a step shape, etc., by a power amplifier 3 in which an output is made variable in accordance with a gain signal from a gain variable part 30a in accordance with the action timing of an action time control part 30b, and a testing signal is recorded to a magnetic tape 10. For an action time corresponding to a memory 31 controlled by the microcomputer part 30 while a recorded testing signal is reproduced, a reproducing level is stored. When a memory current is adjusted in the same way so that the reproducing level can correspond to the memory contents, an optimum current recording can be easily executed without being influenced by the secular change regardless of the characteristic of the magnetic head and the tape.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a multiplex magnetic recording/reproducing device, which records a FM audio signal or records a PCM audio signal on an audio track of a VTR using a multiplex magnetic recording/reproducing system capable of recording and reproducing. related to recording current control.

Prior Art This is a so-called FM audio deep recording method in which an FM audio signal is recorded on a magnetic tape by a rotating magnetic head for audio signals, and a video signal is recorded on this audio track by a rotating magnetic head for video signals. A multiplex magnetic recording/reproducing device is disclosed, for example, in Japanese Patent Application Laid-Open No. 59-127202 (title of invention "Multiple Magnetic Recording Device and Multiplex Magnetic Recording/Reproducing Device").
) is proposed.

On the other hand, a VT that records a PCM audio signal instead of an FM audio signal on the audio track
R has been researched and developed in recent years, for example, ICASSP86
'Research on recording IPCM audio on VTR' was announced in April.

Problems to be Solved by the Invention In a VTR that records a PCM audio signal on an audio track as described above, since a video signal is recorded on the PCM audio signal, various problems arise as follows. .

For example, due to wear of the magnetic head, the recording current of the luminance signal (Y signal) becomes deeper, which causes the problem that the error rate of the PCM audio signal increases as shown in FIG. 6(A). In addition, it is necessary to adjust the sensitivity unevenness of the magnetic head and the variation in recording and reproducing characteristics due to production, and there is a problem in that it requires a lot of man-hours.

Furthermore, as shown in FIG. 6(B), there are many variations in recording and reproducing characteristics (indicated by A) depending on the magnetic tape and magnetic head.
There was a problem that it could not support recording of PCM audio signals. Furthermore, the optimum value of the Y signal differs between magnetic tapes having widely different characteristics, and as shown in FIG. 6(C), there is a problem that this also affects the carrier noise ratio (CZN ratio) versus error rate characteristic.

Furthermore, there is a problem in that it is directly affected by changes over time.

SUMMARY OF THE INVENTION An object of the present invention is to provide a multiplex magnetic recording and reproducing apparatus that can perform optimal recording without relying on magnetic heads or magnetic tapes, and without being affected by aging.

Means for Solving the Problems The present invention provides a recording means for recording on a magnetic tape by sequentially varying the recording current of a luminance signal of a video signal stepwise or continuously at a predetermined timing, and for reproducing signals from the magnetic tape. and a storage means for storing the recording level of the recording means at the timing at which the reproduction output range was obtained.

During recording, the recording current of the luminance signal is changed as shown in Fig. 4 (B), and during reproduction, a predetermined reproduction output range as shown in Fig. 4 (C) is detected. memorize the recording level.

Embodiment FIGS. 1A and 1B are block diagrams of the recording system and reproduction system of an embodiment of the apparatus of the present invention, respectively, and FIG. 2 is a block diagram of the entire digital VTR to which the apparatus of the present invention is applied. shows.

In FIG. 2, during recording, a video signal input to terminal 1 is sent to a video signal recording processing circuit 2. Control amplifier 22. While being supplied to the rotating magnetic head 4 via the power amplifier 3, the L channel and R channel audio signals that have entered the terminals 5L and 5R, respectively, are converted into digital signals by the AD converter 6 and then sent to the audio signal recording processing circuit. The signal is supplied to the rotating magnetic head 4 via a 7.4-phase PSK modulator and 8° amplifier 9, and is recorded on the magnetic tape 10 together with the video signal.

On the other hand, during reproduction, the video signal reproduced from the magnetic tape 10 is transmitted to the reproduction preamplifier 11. Video signal reproduction processing circuit 12
While the magnetic tape 10 is taken out from the terminal 13 through the
The audio signal reproduced by the amplifier 14. The signal is supplied to the synchronization code detector 17 via the equalizer 15 and the 4-phase PSKII modulator 16, where the synchronization code is detected, and then the error is detected by the error detector 18, and then the error is corrected by the audio signal reproduction processing circuit 19. and the DA converter 20
The signal is converted into an analog signal and taken out from terminals 21L and 21R.

Next, the operation of the main parts of the device of the present invention will be explained. Second
The recording 'R flow control circuit 23 in the figure corresponds to the main part of FIG. 1(A), and the reproduction control circuit 24 in FIG. 2 corresponds to the main part of FIG. 1(B). A tuning button is provided on the front panel of the VTR body, and the user operates this tuning button before recording, that is, after loading a cassette tape into the VTR, to detect the optimum recording level of the cassette tape. This operation will be explained below.

In FIG. 1(A), the microcomputer section 30 has data of the playback output range set in advance, and the memory (PROM>3
The operation according to the flowchart shown in FIG. 3 is performed depending on the program in 1.

During recording, the switching signal a shown in FIG. 4(A) is taken out from the microcomputer section 30 via the interface 32 in FIG.
15c is connected to both terminal A side (test terminal side) (
Step 50 in FIG. 3) The signal from the video signal recording processing circuit 2 is cut off, and the test signal (luminance signal recording current) whose carrier frequency and level are set instead
is retrieved from the adjustment signal generator 33 (step 51)
.

The test signal is supplied to the FM modulator 34, subjected to FM modulation, and then supplied to the control amplifier 17.

Here, a variable gain υItE signal corresponding to the operation timing of the operation time control section 30b is taken out from the gain variable section 30a of the microcomputer section 30, converted into an analog signal by the DA converter 25, and sent back to the control amplifier 17. The output of the power amplifier 3 is varied stepwise (step 52).

As a result, the recording level of the test signal is varied stepwise and recorded on the magnetic tape 10 as shown in FIG. 4(B). Note that the voltage of the magnetic head 4 is controlled by a rectifier circuit 35.
The voltage is converted into a DC voltage and applied to the DA converter 21.

In addition to the above embodiment, a circuit shown in FIG. 5 may be used as means for varying the recording level of the test signal in a stepwise manner. The circuit shown in the figure includes a DA converter 25 (substantially an input resistor) at the e-input end of the amplifier 22, and the gain of the amplifier 22 is varied by varying the resistance value with a variable gain control signal from the memory 31. The output of the amplifier 22 is taken out via the power amplifier 3. This device records by equivalently converting the recording current of the Y signal into a recording voltage.

On the other hand, for the audio system, as shown in FIG. 2, an error detection signal is added to the output of the random data generator 36 by an error detection signal generator 37, and the output is recorded on the magnetic tape 10 by the rotary head 4.

During playback, in FIG. 1B, the magnetic tape 10 on which the test signal has been recorded is rewound and played back by a tape rewind control signal from the microcomputer section 30 (step 53).
, the reproduction output level has a waveform shown in FIG. 4(C), for example.

An operation timing control signal from the operation time control section 30b of the microcomputer section 30 is supplied to the AD converter 38, and the operation timing is sequentially varied (step 54). The microcomputer unit 30 constantly monitors the playback output level at each operating time, and when it is detected as the optimum value within the playback output range at time t (step 55), the DA is set at time t when this signal is recorded. The value of the register given to converter 25 is stored in memory 31 (step 56). This reproduction output range is the value for obtaining the gain of the control amplifier 22 that allows optimal recording.

Note that the recording current may be continuous as well as step-like.

Moreover, the signal a shown in FIG. 4(A) is used as a drum pulse.
In addition to recording at a variable recording level in a field period, recording may be performed at a variable recording level in units of several fields.

On the other hand, regarding the audio system, as shown in FIG. 2, the output error detection signal of the error detector 18 is supplied to the microcomputer section 30 via a buffer and interface 39, and the audio reproduction signal is error-corrected.

Effects of the Invention According to the present invention, even if the magnetic head wears out, the recording current for the Y signal does not become deeper, and as a result, the error rate of the PCM audio signal does not worsen, and the head Sensitivity unevenness, variations in recording and playback characteristics, etc. are automatically adjusted, reducing the number of adjustment steps.Furthermore, it is possible to eliminate variations in the recording and playback characteristics of magnetic tapes, and the tape performance is always maintained even if there are magnetic tapes with different characteristics. It has the characteristics of being able to sufficiently bring out the error rate, improving the error rate, and not being affected by aging.

FIG. 2 is a block system diagram of the entire digital VTR to which the device of the present invention is applied, FIG. 3 is a flow chart for explaining the operation of the VL device of the present invention, FIG. 4 is a timing chart for explaining the operation of the device of the present invention, and FIG. 5 6 is a block diagram of a part of another embodiment of the apparatus of the present invention, and FIG. 6 is a characteristic diagram showing the relationships among Y recording current, error rate, Y reproduction output, and C/N ratio.

4... Rotating magnetic head, 10... Magnetic tape, 22
... Control amplifier, 23 ... Recording M flow control circuit, 24
...Reproduction control circuit, 25...DA converter, 30...
・Microcomputer section, 30a...Gain variable section, 30b...
- Operating time control section, 31... memory, 33... adjustment signal generator, 34... FM modulator, 38... AD converter.

Figure 3 ■ WrrIfl - Figure 6 YA ball: r477 - . 1. - C/N rj
+ -1 procedure? tti official document 1, Indication of the case 1986 Patent application No. 239825 2, Name of the invention Multiplex magnetic recording and reproduction 5A 3, Person making the amendment Relationship to the case Patent applicant address 221 Kanayo Ward, Yokohama City, Kanagawa Prefecture 3-12 Moriyamachi Name (432) Victor Japan Co., Ltd. Representative Director and President Kunio Kakimoto 4, Agent Address 5-7-5 Kojimachi, Chiyoda-ku, Tokyo 102
, date of correction order 'y
-'! jT+'-04,F! -6, 6. Detailed description of the invention in Book II that is the subject of the amendment.

Supplied, J is corrected as shown in the following sentence on page 10, line 9 of the correction contents statement. The output error detection signal is supplied to the audio signal reproduction processing circuit 19.

Claims (2)

[Claims] (1) Has a video track and an audio track,
In a multiplex magnetic recording and reproducing device using a rotating magnetic head that records a PCM audio signal on the audio track and then records a video signal thereon and reproduces the same, the recording current of the luminance signal of the video signal is stepped at a predetermined timing. or recording means for recording on a magnetic tape in a continuous and sequential manner; a detection means for reproducing a signal from the magnetic tape and detecting its level at the predetermined timing to detect a predetermined reproduction output range; A multiplex magnetic recording/reproducing apparatus comprising a storage means for storing the recording level of the recording means at the timing at which the output range was obtained. (2) The recording means is a means for equivalently converting the recording current of the luminance signal into a recording voltage and recording it on the magnetic tape while varying it sequentially in a stepwise or continuous manner at the predetermined timing. A multiple magnetic recording/reproducing apparatus according to claim 1.