JPH0628438B2 - Recording / playback device - Google Patents

Description

The present invention relates to a television signal recording / reproducing apparatus.

[Conventional technology]

In this type of conventional recording / reproducing apparatus, the recording current is manually set so that the television signal is recorded / reproduced simultaneously and the reproduced signal level shown on the display or the like is maximized.

[Problems to be solved by the invention]

In the above-mentioned conventional recording / reproducing apparatus, the recording current is adjusted so that the radio frequency (RF) signal becomes maximum, so that the secondary distortion is not always the minimum. Then, in the direct FM recording of the image, the secondary distortion appears on the screen as a moire, which deteriorates the image quality. Further, there is a drawback that the recording current must be readjusted each time the recording medium is changed, or when the recording head is worn out in the magnetic recording medium and the laser diode is deteriorated or the temperature is changed in the optical recording medium. .

[Means for solving problems]

The recording / reproducing apparatus of the present invention comprises means for switching the recorded television signal to a harmonic distortion detection signal and recording it on a recording medium during a part of a blanking period of the television signal recorded at the time of recording the television signal, Means for reproducing the harmonic distortion detection signal immediately after recording in this means, and means for respectively detecting a fundamental wave component and a second harmonic component from the harmonic distortion detection signal reproduced by this means, And a means for controlling the recording current so that the ratio of the second harmonic component to the fundamental wave component of the reproduced signal of the harmonic distortion detection signal is minimized.

[Action]

In the present invention, the fundamental wave and the second harmonic are extracted from the reproduction signal, the ratios of them are compared, and the recording current is automatically increased / decreased in the direction of reducing the harmonic distortion. The optimum recording current is set automatically.

〔Example〕

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, and shows an example in which the present invention is applied to a magneto-optical disk system.

In FIG. 1, reference numeral 1 is an RF amplifier which receives a reproduction signal a from a recording / reproducing head 17 and amplifies it to output an RF signal to bandpass filters 2a and 2b tuned to 9 MHz and 18 MHz, respectively, and 3a and 3b. A rectifier circuit that receives the signals S _1d and S _1b output from the bandpass filters 2a and 2b, and outputs the rectified signal to the sample and hold circuits 4a and 4b.The sample and hold circuits 4a and 4b sample the input signal. Then, the signals S _2a and S _2b are output to the A / D converters 5a and 5b. With this A / D converter 5a, 5b
The A / D converted signals (digital data) S _3a and S _3b are output to the data bus 7 via the input ports 6a and 6b. The data bus 7 has a central processing unit 11 (CPU) for arithmetic control processing, a read-only memory 10 (ROM) in which a control program is written, and a random access memory 9 (8 bits × 2 words). RAM) is connected.
Then, the recording current control data S ₄ input from the data bus 7 to the D / A converter 12 through the output port 8 is converted into an analog signal and output to the recording amplifier 13 as a recording current control signal S ₅ .

On the other hand, the pulse signal S ₉ from the tack pulse circuit 20 is input to the timing circuit 16 and the timing circuit 16
More clock C is output. Then, at the timing of this clock C, the switch 15 outputs the DC signal S ₇ to the FM modulator 14.

Then, this DC signal S ₇ is FM-modulated by the FM modulator 14 and output to the recording amplifier 13,
Outputs the recording signal S ₈ to the recording / reproducing head 17 with the recording current determined by the recording current control signal S ₅ output from the D / A converter 12.

The laser diode 17a of the recording and reproducing head 17 is emitted as input the recording signal S _8, the magneto-optical disc 1
This recording signal S ₈ is recorded at ₈ . Reference numeral 19 is a spindle, and 21 is a spindle servo circuit.

The recording amplifier 13, the FM modulator 14, the switch 15, the timing circuit 16, the recording / reproducing head 17 and the magneto-optical disk 18 are recorded in a part of the blanking period of the television signal recorded at the time of recording the television signal. The recording / reproducing head 17 constitutes a recording means for switching the television signal to a harmonic distortion detection signal and recording it on a recording medium. The recording / reproducing head 17 reproduces the harmonic distortion detection signal immediately after recording by the recording means. Means and also RF
Bandpass filters 2a and 2b with the output of amplifier 1 as input
Is means for detecting the fundamental wave component and the second harmonic component from the harmonic distortion detection signal reproduced by the reproducing means, and further, the output port 8, the RAM9, the ROM10, the CPU11 and the D / A converter. Reference numeral 12 constitutes means for controlling the recording current so that the ratio of the second harmonic component to the fundamental wave component of the reproduced signal of the harmonic distortion detection signal is minimized.

The operation of the embodiment shown in FIG. 1 will be described below with reference to FIGS.

FIG. 2 is a characteristic diagram showing a linear relationship between the recording current control data S ₄ output from the output port 8 and the recording current, and FIG. 3 is a recording current and the light on the surface of the magneto-optical disk 18. FIG. 4 is a characteristic diagram showing the relationship with the output, and FIG. 4 is a characteristic diagram showing the relationship between the recording current and the fundamental wave (C / N) and the second harmonic (C ₂ / N).

First, the bandpass filter 2a is a filter tuned to the fundamental wave, and the bandpass filter 2b is a filter tuned to the second harmonic. The RF signal amplified by the RF amplifier 1 is a signal S _1a having only the fundamental wave component. The signal S _{1b has} only the second harmonic component. The signals S _1a and S _1b are rectified by the rectifier circuits 3a and 3b, respectively, and the sample hold circuit 4
Sampling is performed at a and 4b, and signals S _2a and S _2b are output. Here, this sample hold circuit 4a, 4b
The timing of sampling in the timing circuit 1
Clock C from 6 is used. The clock C is a signal output from the timing pulse circuit 20 after a certain delay is added to the pulse signal S ₉ detected by the tack pulse circuit 20 and output by detecting the rotation of the spindle 19.

Then, A / D converter 5a, 5b converts the sample-and-hold circuit 4a is an analog signal, signal S _2a from 4b, and S _2b digital data S _3a, the S _3b, the input port 6a, data through 6b bus 7 Output signal to. Then, the central processing unit 11 (CP
In (U), the data from the input ports 6a and 6b are processed,
The ratio between the fundamental wave component and the second harmonic component is compared with the data stored in the random access memory 9 (RAM).
Then, the recording current control data S ₄ for giving the optimum recording current by the program stored in the read-only memory 10 (ROM) is passed through the output port 8 to the D / A converter 1
2 is output. The recording current control signal S ₅ converted into an analog signal by the D / A converter 12 is output to the recording amplifier 13 to set the optimum recording current.

On the other hand, the DC signal S ₇ output from the switch 15 switched by the clock C output from the timing circuit 16 is input to the recording amplifier 13 after being modulated by the FM modulator 14. Then, the laser diode 17a in accordance with the signal S ₈ output from the recording amplifier 13 oscillates emission, recorded on the magneto-optical disc 18 is performed.

Next, a specific example will be described.

First, every time the spindle 19 makes one revolution, a pulse signal S ₉ is generated from the tack pulse circuit 20 and input to the timing circuit 16. Here, this pulse signal S ₉ has a delay time (provisionally 6H381 μs) and is output as the clock C to the switch 15 and the sample hold circuits 4a and 4b. Then, the switch 15 is a normal video signal S
₆ is output and switches at the timing of clock C from the timing circuit 16, and the DC signal S of frequency 9 MHz is output.
₇ is output. This DC signal S ₇ is F
M modulation is performed, and the modulated output is amplified by the recording amplifier 13.

Next, the laser diode 17a oscillates in accordance with the input of the recording amplifier 13 in the amplified signal S _8, the magneto-optical disc 18 by the recording current prescribed by a recording current control signal S ₅ from the D / A converter 12 Make a record. The signal recorded on the magneto-optical disk 18 is reproduced by the recording / reproducing head 17, and the reproduced signal a is amplified by the RF amplifier 1.

Next, the output signal of this RF amplifier 1 is bisected and
Are input to the bandpass filters 2a and 2b which are tuned to the fundamental wave and the second harmonic of 18 MHz, respectively. Then, the signals S _1a and S _{1b, which} have only a single frequency component by the bandpass filters 2a and 2b, are rectified and sampled by the rectification circuits 3a and 3b and the sample and hold circuits 4a and 4b by a well-known technique. Here, the clock C output from the timing circuit 16 is used as the sampling timing.

The signals S _2a and S _2b sampled by the sample and hold circuits 4a and 4b are A / D converted by the A / D converters 5a and 5b, and the digital data S _3a and S _3b which are the outputs thereof are input ports 6a, respectively. , 6b and the data bus 7, and the ratio is calculated by the central processing unit 11 (CPU). Then, in the random access memory 9 (RAM), the recording current control data defining the optimum recording current up to the previous processing, the ratio of the fundamental wave component and the second harmonic component at that time, and the current signal are recorded. The recording current control data at the time of recording is stored, which is compared and judged by the central processing unit 11 (CPU), and the optimum recording current control data S ₄ is output from the output port 8. This recording current control data S ₄ is used for the D / A converter 12
Becomes an analog signal and is input to the recording amplifier 13 to determine the recording current.

〔The invention's effect〕

As described above, according to the present invention, by comparing the ratio of the fundamental wave and the second harmonic of the reproduction signal, the optimum recording current is always automatically set for various recording media, Since an image signal with less secondary distortion can be reproduced, the practical effect is extremely large.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIGS. 2 to 4 are characteristic diagrams for explaining the operation of FIG.
FIG. 2 is a characteristic diagram showing a linear relationship between the recording current control data and the recording current, FIG. 3 is a characteristic diagram showing the relationship between the recording current and the optical output on the magneto-optical disk surface, and FIG. It is a characteristic view which shows the relationship with a fundamental wave and a second harmonic. 1 ... RF amplifier, 2a, 2b ... Band pass filter, 3a, 3b
...... Rectifier circuit, 4a, 4b …… Sample and hold circuit, 5a, 5b
...... A / D converter, 6a, 6b …… input port, 7 …… data bus, 8 …… output port, 9 …… RAM, 10 …… ROM,
11 ... CPU, 12 ... D / A converter, 13 ... Recording amplifier, 14 ... FM modulator, 15 ... Switch, 16 ...
... Timing circuit, 17 ... Recording / playback head, 17a ...
… Laser diode, 18… Magneto-optical disk, 19
...... Spindle, 20 ... Tac pulse circuit, 21 ...
Spindle servo circuit.

Claims (1)

[Claims] 1. A television signal recording / reproducing apparatus, wherein the television signal to be recorded is switched to a harmonic distortion detection signal during a part of a blanking period of the television signal to be recorded at the time of recording the television signal. Recording means, a means for reproducing the harmonic distortion detection signal immediately after recording by this means, and a fundamental wave component and a second harmonic wave from the harmonic distortion detection signal reproduced by this means. And a means for controlling the recording current so that the ratio of the second harmonic component to the fundamental wave component of the reproduction signal of the harmonic distortion detection signal is minimized. Recording / playback device.