JP3170150B2 - Magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus using a magnetic recording medium, and more particularly to a magnetic recording / reproducing apparatus capable of performing optimum recording according to a recording medium.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram of a conventional magnetic recording / reproducing apparatus. In the drawing, in a recording system circuit, an input video signal is extracted as a luminance signal via a low-pass filter (LPF) 1 and a band-pass filter (BPF).
7 and is extracted as a chroma signal.

A luminance signal extracted from the low-pass filter 1 is guided to a fixed recording equalizer circuit 26 via a pre-emphasis circuit 2, a white / dark (W / D) clip circuit 3, and an FM modulator 4. Note that the W / D clip circuit 3 is provided for preventing white- and dark-side whiskering (overmodulation) of the pre-emphasized luminance signal.

The chroma signal output from the band-pass filter 7 is guided to an ACC circuit 8 for the chroma signal, a low-frequency conversion circuit 9 for the chroma signal, and a low-pass filter 10 for passing the low-frequency-converted chroma signal. In the Y / C mixing circuit 6, the low-frequency conversion chroma signal and the luminance FM wave signal from the fixed recording equalizer circuit 26 are mixed and guided to a head via a recording amplifier (not shown).

In a reproduction system circuit, a reproduction luminance FM is input from an input reproduction signal via a high-pass filter (HPF) 14.
Separate and take out the wave, low-pass filter (LPF) 2
1 to separate and extract the reproduced low-frequency-converted chroma signal.

The reproduction luminance FM wave extracted by the high-pass filter 14 is demodulated by an FM demodulator 15, subjected to de-emphasis by a de-emphasis circuit 16, and to a Y / C mixing circuit 25.

The reproduced low-frequency conversion chroma signal extracted by the low-pass filter 21 is guided to the high-frequency conversion circuit 23 via the ACC circuit 22, and the signal converted to the low frequency (629 KHz ± 500 KHz) is converted to the high frequency (3. 58MHz ± 500KHz)
The signal is inversely converted into a signal, and unnecessary noise and the like are removed in a band-pass filter (BPF) 24 and guided to a Y / C mixing circuit 25, where it is mixed with a reproduced luminance signal and output, and output to a video output and an RF converter. You.

[0008]

In the above-mentioned conventional magnetic recording / reproducing apparatus, an equalizer circuit for recording luminance FM waves of a recording system circuit has a fixed characteristic, and a low-frequency conversion chroma signal insertion band (629 KHz ± 500 KHz). Even if a measure such as leaving a gap or having a fixed switching recording current characteristic is taken, the recording characteristic is quite fixed. There were inconveniences such as worsening.

An object of the present invention is to provide a magnetic recording / reproducing apparatus capable of performing optimum recording according to a recording medium to be used.

[0010]

SUMMARY OF THE INVENTION A magnetic recording / reproducing apparatus according to the present invention is provided with a recording equalizer means capable of changing the recording characteristics of a video signal at a recording luminance FM, and for recording a white peak signal as a check signal on a recording medium. Recording control means, reproduction control means for reproducing a white peak signal recorded on the recording medium, an original white peak signal recorded on the recording medium, and a reproduced white peak signal reproduced from the recording medium Comparison means for comparing the presence or absence of a reversal phenomenon based on the comparison result of the comparison means ,
Judge whether the noise level is higher than the set value and invert the phenomenon.
None and if the noise level is below the set value, the recording current
Other peaks to lower the frequency
In this case, there is no inversion phenomenon and the noise level is below the set value.
Recording characteristic control means for outputting a control signal for controlling the recording equalizer means so as to obtain the optimum recording current characteristic for the recording medium .

[0011]

[0012]

[0013]

According to the magnetic recording / reproducing apparatus of the present invention, the check signal and the
Using the white peak signal,
After recording the white peak signal for a certain period of time, rewind
And play back, and the playback white peak signal and original white
With the light peak signal, and based on the comparison result,
The presence or absence of the inversion phenomenon and the noise level are determined .

[0014]

[0015]

If there is no inconvenience in this discrimination result, the peak of the recording frequency characteristic of the recording equalizer circuit is moved and adjusted in a lower direction to achieve higher definition of the image quality. The recording current characteristics of the equalizer circuit are changed, and the recording current characteristics optimal for the recording medium are automatically set. As a result, the occurrence of reversal phenomena and the deterioration of the SN ratio due to the type and quality of the recording medium are prevented, and higher image quality is achieved. After the reproduction for this discrimination, the recording medium can be returned to the starting position and stopped, and the subsequent magnetic recording can be put on standby with the optimum recording current characteristics of the recording medium.

[0017]

FIG. 1 is a block diagram showing an embodiment of a magnetic recording / reproducing apparatus according to the present invention. The same components as those shown in FIG. 5 are designated by the same reference numerals. In the drawing, a variable recording equalizer circuit 5 that can be set and changed is provided in place of a fixed recording equalizer circuit 26, and a recording control circuit 11, a white peak signal generator 12, and a synchronization separation circuit 13 are provided in the recording system circuit. Have been.

In the reproduction system circuit, a subtraction circuit 17, a first level comparison / control signal generator 18, a noise extraction limiter circuit 19, a second level comparison control signal generator are provided on the output side of the de-emphasis circuit 16. 20 are provided. The other configuration is the same as the configuration shown in FIG.

In this apparatus, when a recording medium such as a cassette tape is inserted into a set, a control microcomputer (not shown) senses this and starts the recording medium, and a recording control circuit 11 and a white peak signal generator 12
A control signal is generated, and a white peak signal is supplied to a recording luminance signal processing line (in this case, a pre-emphasis circuit 2), processed as a recording luminance signal, and recorded on a recording medium for 1 to 2 seconds.

At this time, the white peak signal from the white peak signal generator 12 is synchronized with the synchronization signal from the synchronization separation circuit 13, and the main signal processing line in the pre-emphasis circuit 2 is not operated.

Next, the recording medium is stopped and returned to the starting point to be reproduced. The reproduced signal is demodulated by the FM modulator 15 and de-emphasized by the de-emphasis circuit 16, and then supplied to the subtraction circuit 17. In the subtraction circuit 17, as shown in FIG.
The difference between the white peak signal Sa and the reproduced white peak signal Sb is obtained. As a result, if an inversion phenomenon occurs, the inversion phenomenon noise Na and the high-frequency noise Nb
Are taken out.

The inversion phenomenon noise Na thus extracted
Is input to the first level comparison / control signal generator 18,
The control voltage is compared with a preset noise level, and a control voltage corresponding to the difference level is supplied to the recording equalizer circuit 5 as control signals Cb and Cc.

The high frequency noise Nb is guided to a noise extraction limiter circuit 19, where only the noise is extracted and subjected to a limiter, and then supplied to a second level comparison / control signal generator 20. In the second level comparison / control signal generator 20, the control signal Ca is compared with a preset noise level, and a control signal Ca corresponding to the difference level is supplied to the variable recording equalizer circuit 5, and the recording current characteristic, that is, recording is performed. The frequency characteristics are variably adjusted.

Next, adjustment of recording current characteristics in the variable recording equalizer circuit 5 will be described. FIG. 3 is a block diagram showing an embodiment of the variable recording equalizer circuit 5, in which a capacitor C1 (0.01 μF), a variable capacitor (hereinafter referred to as a varicap) VCb (82 pF), and a varicap V
Cc (220 pF) and a variable volume VR for recording level adjustment are connected in series, and a coil L is connected between the connection middle point of the capacitor C1 and the varicap VCb and the ground.
1 (150 μH) and capacitor C2 (390 pF)
Are connected in series. Similarly, a varicap VCa (180 pF) and a resistor R1 (1 KΩ) are connected in series between the connection midpoint of the capacitor C1 and the varicap VCb, and the varicap VCb and the varicap Vc.
The coil L2 (56 μm) is connected between the connection middle point of Cc and the ground.
H) is connected, and the coil L is connected in parallel with the varicap VCc.
3 (150 μH) is connected.

The variable band of the varicap VCa is changed by the 1KΩ resistor by the variable adjustment by the control signal Ca, and the slope of the portion around 5 MHz or more changes. Further, the inclination of the varicap VCb on the low frequency side from the peak is changed by the variable adjustment using the control signal Cb. Further, the varicap VCc is set to 150 μH by variable adjustment using the control signal Cc.
The peak moves to the frequency of resonance with the coil.

FIG. 4A shows a recording current characteristic in the recording equalizer circuit 5 in a case where the peak value (peak value) is normally fixed at around 2 MHz. Here, when the capacity of the varicap VCa becomes large, as shown by a circle b in FIG. 4B, the low-frequency region side of the recording current characteristic bulges in the direction of low frequency, and a more accurate reproduced image is obtained. Can be Conversely, when the capacity of the varicap VCa is reduced, this characteristic is depressed and the resolution tends to decrease.

When the capacity of the varicap VCc is large, the peak of the recording current characteristic moves to a low frequency range as shown by an arrow c in FIG. 4B, and when the capacity is small, the peak moves to a high frequency range. Will do. In addition, Varicap VCa
In the case of the large capacity, as shown by the arrow a in FIG. 4B, the gradient of the high frequency region of the recording current characteristic becomes gentle, and the high frequency region current increases.

Therefore, when the magnetic recording medium used has a reversal phenomenon, a signal is issued to adjust both the capacity of the varicap VCb and the capacity of the varicap VCc to a small value.
The recording current characteristic is such that the low-frequency band and the high-frequency band are balanced in recording and reproduction to prevent the reversal phenomenon.

When the reversal phenomenon does not occur, the capacity of the varicap VCb and the capacity of the varicap VCc are adjusted so as to obtain high resolution and high image quality. If it is determined that the noise level is large, the capacity of the varicap VCa is controlled to be large, and the recording current characteristic is such that the high-frequency current is increased to reduce the relative amount of noise.

As described above, according to the present invention, as a result of the recording equalizer circuit being variably adjusted in accordance with the type and characteristics of the recording medium to be used, an optimum recording current characteristic for each recording medium to be used is obtained. It will be set each time.

Following the setting of the recording current characteristics, new recording can be performed below the precursor recording section. However, it is also possible to perform new recording by the user after returning to the starting point of the recording medium.

In the above embodiment, an example is shown in which the precursor recording mechanism is controlled by a microcomputer.
Sequence control using a relay, a timer, or the like can also be performed. Further, in the recording medium pre-recording, the recording can be performed by changing the speed arbitrarily to SP, LP / EP or the like.

[0033]

According to the magnetic recording reproducing apparatus of the present invention, Ji
Record white peak signal on recording medium as check signal
After playing back, playback white peak signal and original white
Whether the reversal phenomenon has occurred based on the comparison with the peak signal
And the noise level is determined, and according to the result,
The recording equalizer is variably adjusted to optimize the recording for the recording medium.
Recording characteristics, depending on the type of recording medium
It is possible to prevent the occurrence of the inversion phenomenon and the deterioration of the SN ratio.
Therefore, high image quality can be realized .

[0034]

[0035]

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a magnetic recording / reproducing apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing an example of inversion phenomenon detection and noise detection and an example of control signal generation.

FIG. 3 is a circuit diagram illustrating an example of a recording equalizer circuit.

FIG. 4 is a characteristic diagram showing an example of adjusting a recording current characteristic in a recording equalizer circuit.

FIG. 5 is a block diagram of a conventional magnetic recording / reproducing apparatus.

[Explanation of symbols]

 2 Pre-emphasis circuit 4 FM modulator 5 Variable recording equalizer circuit 11 Recording control circuit 12 White peak signal generator 13 Synchronization separation circuit 15 FM demodulator 16 De-emphasis circuit 17 Subtraction circuit 18 First level comparison / control signal generator 19 Noise extraction limiter circuit 20 Second level comparison / control signal generator

Claims (1)

(57) [Claims] 1. A recording equalizer means capable of changing a recording characteristic of a recording luminance FM wave of a video signal, a recording control means for recording a white peak signal as a check signal on a recording medium, and a recording control means for recording on a recording medium. Reproduction control means for reproducing a white peak signal; comparison means for comparing an original white peak signal recorded on the recording medium with a reproduction white peak signal reproduced from the recording medium; and a comparison result of the comparison means. Based on the presence or absence of a reversal phenomenon
And whether the noise level is higher than the set value
If there is no phenomenon and the noise level is below the set value, the recording power
In order to shift the peak of the flow characteristic to the low frequency range,
Outside, no inversion phenomenon and noise level is below the set value
And a recording characteristic control means for outputting a control signal for controlling the recording equalizer means so as to obtain optimum recording current characteristics for the recording medium to be used.