JPS62131678A - Recording and reproducing device - Google Patents

Abstract

PURPOSE:To always set an optimum recording current automatically to various recording media by extracting a fundamental wave and the 2nd harmonic from a reproducing signal in reproducing a television signal and comparing the ratio of them so as to adjust the recording current automatically in a direction decreasing the harmonic distortion. CONSTITUTION:Signals S2a, S2b sampled by sample holding circuits 4a, 4b are subjected to A/D conversion by A/D converters 5a, 5b and digital data S3a, S3b being the output are subjected to ratio calculation by a central processing unit 11 (CPU) through input ports 6a, 6b and a data bus 7 respectively. Then a recording current control data deciding the optimum recording current up to the preceding processing the ratio of the fundamental component to the 2nd harmonic in this case and the recording current control data in recording the signal this time are stored in a random access memory (RAM) 9, and they are compared and discriminated by the CPU 11. Further, the optimum recording current control data S4 is outputted from an output port 8. In comparing the ratio of the fundamental wave to the 2nd harmonic of the reproducing signal in this way, the optimum recording current is always set automatically and the picture signal without the second order distortion is reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a recording and reproducing apparatus for television signals.

[Conventional technology]

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

[Problem that the invention seeks to solve]

In the conventional recording/reproducing apparatus described above, the recording current is adjusted so that the radio frequency (RF) signal is maximized, so the second-order distortion is not necessarily minimized.

In FM recording, second-order distortion appears on the screen as moiré, degrading the image quality. Another drawback is that the recording current must be readjusted each time the recording medium is changed, or in response to wear of the recording head in magnetic recording media, deterioration of the laser diode or temperature changes in optical recording media, etc. There is.

[Means for solving problems]

The recording and reproducing apparatus of the present invention includes means for switching the recorded television signal to a harmonic distortion detection signal and recording it on a recording medium during a part of the retrace period of the television signal recorded when recording the television signal; means for reproducing the harmonic distortion detection signal immediately after it is recorded in the means; means for detecting a fundamental wave component and a second harmonic component from the harmonic distortion detection signal reproduced by the means; and 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 wave distortion detection signal is minimized.

[Effect]

In the present invention, the fundamental wave and the second harmonic are extracted from the reproduced signal, their ratio is compared, and the recording current is automatically increased or decreased in the direction of reducing harmonic distortion. The optimal recording current is always automatically set.

〔Example〕

Embodiments of the present invention will be described in detail below based on the drawings.

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

In FIG. 1, 1 receives the υ reproduction signal a from the recording/reproducing head 1T, amplifies it, and amplifies it, respectively.9M) 1! +
Bandpass filter 2 tuned to 18MHz
RF amplifier that outputs RF multiplied signal to 1 and 2b, 3m,
3b is a rectifier circuit that receives the signal S1d+S1b outputted from the band pass filters 2m and 2b, respectively, and outputs the rectified signal to the sample and hold circuits 4a and 4b.The sample and hold circuit 4m+4b samples the input signal and converts the signal to the LΦ converter. It is configured to output a signal 82m+S2b to 51°5b.

A signal (digital data) Ssa + S3b is A/D converted by the A/D converters 5m and 5b and is output to the data bus γ via the input capo) 6m and 6b. Here, this data bus T includes a central processing unit 11 (CPU) that performs arithmetic and control processing, a read-only memory 10 (ROM) in which control programs are written, and a rachidham access memory 9 with an 8-bit x 2-word configuration. (
RAM) is connected. The recording current control data S4 input from the data bus 7 to the D/A comparator 12 through the output port 8 is converted into an analog signal and outputted to the recording amplifier 13 as a recording current control signal S.

On the other hand, the pulse signal S9 from the tack pulse circuit 20 is input to the timing circuit 16.
Outputs a clock C. Then, according to the timing of this clock C, the switch 15 outputs the DC signal S7 to the FM modulator 14.

This DC signal S7 is then FM modulated by the FM modulator 14 and output to the recording amplifier 13.
outputs a recording signal S8 to the recording/reproducing head 1T with a recording current determined by a recording current control signal S5 output from the D/A converter 12.

The laser diode 17m of this recording/reproducing head 1T receives the recording signal S8 as input and emits light, and this recording signal S8 is recorded on the magneto-optical disk 18. 19 is a spindle, and 21 is a spindle servo circuit.

Then, the recording amplifier 13. FM modulator 14° switch 15. Timing circuit 16. The recording and reproducing head 1T and the magneto-optical disk 18 switch the recorded television signal to a harmonic distortion detection signal and record it on the recording medium during a part of the retrace period of the television signal recorded when recording the television signal. The recording and reproducing head 17 constitutes a reproducing means for reproducing the harmonic distortion detection signal immediately after being recorded by the recording means, and the R
Bandpass filter 2m with the output of F amplifier 1 as input
, 2b constitute means for respectively detecting the fundamental wave component and the second harmonic component from the harmonic distortion detection signal reproduced by the reproduction means, and the output ports 8 and RA
The M9, the ROM 10, the CPU 11, and the D/A converter 12 constitute means for controlling the recording current so that the ratio of the second harmonic component to the fundamental component of the reproduction signal of the harmonic distortion detection signal is minimized.

Next, the operation of the embodiment shown in FIG. 1 will be explained with reference to FIGS. 2 to 4.

FIG. 2 shows a characteristic diagram showing the linear relationship between the recording current control data S4 output from the output port 8 and the recording current, and FIG. 3 shows the recording current and the light on the surface of the magneto-optical disk 18. FIG. 4 is a characteristic diagram showing the relationship between the recording current and the fundamental wave (to C) and the second harmonic (to Cz).

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, and the RF signal amplified by the RF amplifier 1 is a signal S1. This results in a signal Stb having only the second harmonic component. Each of these signals S1. lS and b are rectified by rectifier circuits 3m and 3b, sample and hold circuits 4m and 4b perform sampling, and signals 82g+S2b are output, respectively. Here, this sample hold circuit ja
, 4b uses the clock C from the timing circuit 16. Clock C is a signal that is output after adding a certain amount of delay in the timing circuit 16 to the pulse signal S9 that the tack pulse circuit 20 outputs by detecting the rotation of the spindle 19. Next, the A/D Converters 5m and 5b are analog signals. Signals 8 from sample and hold circuits 4m and 4b
2@r S2b as digital data ssa l Ssb
and outputs the signal to the data bus 7 through the input port a r 6b. Then, the central processing unit 11 (
The CPU) processes the data from the input capacitors 6m and 6b, and compares the ratio of the fundamental wave component to the second harmonic component with the data stored in the random access memory 9 (RAM). And read-only memory 10 (
Recording current control data S4 that provides an optimum recording current according to a program stored in the ROM (ROM) is outputted to the D/A converter 12 through the output port 8. This D/A
The recording current control signal S5 converted into an analog signal by the converter 12 is output to the recording amplifier 13 to set the optimum recording current.

On the other hand, the recording amplifier 13 is inputted with a DC signal S7 outputted through a switch 15 which is switched in accordance with a clock C outputted from a timing circuit 16, after being modulated by a y modulator 14. The laser diode 17& emits oscillation in accordance with the signal S8 output from the recording amplifier 13, and recording is performed on the magneto-optical disk 18.

Next, a specific example will be given and explained.

First, every time the spindle 19 rotates once, a pulse signal S9 is generated from the tack pulse circuit 20 and input to the timing circuit 16. Here, this pulse signal S9 has a delay time (temporarily 6H; 381 μS), and a switch 15 and a sample hold circuit 4m serve as a clock C.
4b. This switch 15 normally outputs the video signal S6, and is switched at the timing of the clock C from the timing circuit 16, with a frequency of 9.
Outputs a MHz DC signal S7. This DC signal S7 is FM modulated by the FM modulator 14, and the modulated output is amplified by the recording amplifier 13.

Next, the laser diode 17m oscillates in accordance with the input of the signal SS amplified by the recording amplifier 13, and records on the magneto-optical disk 18 with a recording current determined by the recording current control signal Ss from the D/A converter 12. conduct. and,
The signal recorded on the magneto-optical disk 18 is reproduced by the recording/reproducing head 1T, and the reproduced signal stream is amplified by the RF amplifier 1.

Next, the output signal of this RF amplifier 1 is divided into three equal parts, and 9
The signal is input to band pass filters 2m and 2b tuned to the MHz fundamental wave and the 18 MHz second harmonic, respectively. And this band pass filter 2m,
2b, the signal S has only a single frequency component,
+Stb is rectified and sampled by rectifier circuits 3m and 3b and sample and hold circuits 4m and 4b using well-known techniques. Here, the timing of this sampling uses the clock C that is output multiple times from the timing circuit 16.

The signal s2. sampled by the sample hold circuits 4m and 4b. l S2b is A/D converted by A/D converters 5m and 5b, and the output digital data S3@+S3b is passed through the input port 1°6b and data bus T, respectively, and sent to the central processing unit 11 (CPU). The ratio is calculated. The random access memory 9 (RAM) contains recording current control data that determines the optimum recording current up to the previous processing, the ratio of the fundamental wave component to the second harmonic component at that time, and the current signal. Recording current control data when recording is stored, and this is compared and determined by the central processing unit 11 (CPU), and furthermore, optimal recording current control data S4 is output from the output port 8. . This recording current control data S4 is D/
The A converter 12 outputs an analog signal and inputs it to the recording amplifier 13 to record 1! Decide on the flow.

〔Effect of the invention〕

As explained above, according to the present invention, by comparing the ratio between the fundamental wave and the second harmonic of the reproduced signal, the optimum recording current is automatically set for various recording media. Since it is possible to reproduce an image signal with little secondary distortion, the practical effect is extremely large.

[BRIEF DESCRIPTION OF THE 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.
Figure 2 is a characteristic diagram showing the linear relationship between recording current control data and recording current, Figure 3 is a characteristic diagram showing the relationship between recording current and optical output on the magneto-optical disk surface, and Figure 4 is a characteristic diagram showing the relationship between recording current and optical output. FIG. 3 is a characteristic diagram showing the relationship between a fundamental wave and a second harmonic. 1...-RF amplifier, 2a, 2b...Band pass filter, 3m+3b...Life/rectifier circuit, 4a. 4b...Sample hold circuit, 5m, 5b sample/fist/A/D converter, 6m +6b...1 person capo), 7-...data bus, 8...output boat,
9... ・RAM, 10 ・・I-ROM,
11... CPU, 12... D/A converter, 13... Recording amplifier, 14... FM modulator,
15・φ・・Switch, 16・・・Timing circuit,
1T...recording/reproducing head, 1T1...laser diode, 18...magneto-optical disk, 19...
...Spindle, 20...Tack pulse circuit, 21
・Fist spindle servo circuit.

Claims (1)

[Claims] In a television signal recording and reproducing apparatus, means for switching the recorded television signal to a harmonic distortion detection signal and recording it on a recording medium during a part of the retrace period of the television signal recorded when recording the television signal; , means for reproducing the harmonic distortion detection signal immediately after recording by this means, and detecting a fundamental wave component and a second harmonic component from the harmonic distortion detection signal reproduced by this means, respectively. and means for controlling a recording current so that the ratio of the second harmonic component to the fundamental component of the reproduced signal of the harmonic distortion detection signal is minimized.