JPH01105687A - Magnetic recording and reproducing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic recording and reproducing device, and particularly relates to a magnetic recording and reproducing device, and in particular, frequency-multiplexes a frequency-modulated luminance signal and a chrominance signal converted to a low frequency of the modulated luminance signal to generate luminance. The present invention relates to a circuit effective for correcting low frequency characteristics in a device that flattens recording current frequency characteristics in a signal band, performs magnetic recording, and reproduces the same.

[Conventional technology]

The above-mentioned devices include 8mm video cameras and electronic cameras. Conventionally, the frequency characteristic correction of the low frequency band (particularly the chrominance signal band) was performed before the luminance signal and the chrominance signal are multiplexed, and the recording amplifier was configured to be driven with a constant current to flatten the current frequency characteristic of the luminance signal band.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology can perform low frequency correction both in color and in black and white. ■The correction circuit is simple. No consideration has been given to these points, and it is not possible to correct the low range of the frequency modulated luminance signal during monochrome recording. ■'When attempting to perform low frequency correction only in black and white without affecting the color signal during color, there was a problem in that the circuit would become complicated. Also,
When the color signal is an FM signal as in an electronic still camera, there has been no example suggesting effective low-frequency correction characteristics.

It is an object of the present invention to provide a magnetic recording and reproducing device equipped with a correction circuit that can perform low-frequency correction for both color and black-and-white operations, has a simple configuration, and furthermore has a correction characteristic effective in improving S/N. It's about doing.

[Means for solving problems]

The first purpose is to pass the color frequency-modulated luminance signal (Y) through a high-pass filter, pass the low-frequency modulated color signal (C) through a low-pass filter, and after YC multiplexing, transmit the signal before the recording amplifier. Insert a low frequency correction circuit. Further, in black and white, this is achieved by removing the high-pass filter so that Y does not pass through the filter, and cutting C before adding Y and C so that it is not added. The second purpose is to determine the signal-to-noise ratio (
In addition to correcting the characteristics of low frequencies in the recording system so that the S/N ratio is approximately equal, the reproduction system corrects the characteristics of low frequencies so that the levels of the upper and lower sidebands of the color signal input to the FM demodulation circuit are approximately equal. This is achieved by correcting the characteristics.

[Effect]

When in color, the frequency characteristics of the low-frequency modulated color signal of the reproduced signal are the same as in the past, and the single-frequency modulated luminance signal is low-frequency corrected, but there is no problem because unnecessary signals are removed by a high-pass filter.

In black and white, the circuit configuration is such that the high-pass filter for the luminance signal is removed, and the chrominance signal is simply cut off so that it is not input, so the luminance signal is low-frequency corrected and the chrominance signal is not recorded. Therefore, low-frequency correction of the luminance signal can be performed without particularly adding a correction circuit.

Further, the correction circuit corrects the frequency characteristics so that the signal-to-noise ratio of the upper and lower sidebands of the reproduced FM color signal is almost equal, and the correction circuit provided in the reproduction system makes the levels of the upper and lower sidebands almost equal. In order to correct the frequency characteristics and supply it to the FM demodulation circuit, the S/
N can be improved.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a block diagram showing one embodiment of the present invention.

In the figure, 1 is a luminance signal input terminal, 2 and 3 are color signal input terminals, 4 and 16 are pre-emphasis circuits, and 5 and 15 are
is an FM modulation circuit, 6 and 20 are high-pass filters 7.13
, 21 is a color/black and white changeover switch, 8 is an addition circuit,
9.19 is a low-frequency correction equalizer, 10 is a current-driven amplifier, 11 is a magnetic head, 12 is a recording/reproduction switch, 14, 23.25 is a low-pass filter, 17
18 is a color difference signal line sequentialization circuit, 18 is a preamplifier 22°27
FM demodulation circuits 24 and 28 are de-emphasis circuits, 2
6 is a monochrome/color detection circuit, 29 is a synchronization circuit, 30.
31 is a mute circuit, 32 is a brightness signal output terminal, 33.
34 is a color signal output terminal, 35 is a luminance signal band reproduction equalizer, 100 is a composite video input terminal, 101 is a Y/C separation circuit, 102 is a killer detection circuit, 103 is a color demodulation circuit, 104 is a luminance signal output terminal, 105 , 106 are color signal output terminals.

First, the operation of the recording signal will be explained. It is input from the decomposed video input terminal 100. The composite signal is separated into a luminance signal and a color signal by a Y/C separation circuit 101, and the luminance signal is input as it is to the luminance signal input terminal 1 via the luminance signal output terminal 104.

Further, the color signal is separated into R-Y and B-Y color difference signals by the color demodulation circuit 103, and sent to color difference signal output terminals 105 and 106.
The signal is inputted to color difference signal input terminals 2 and 3 via.

The killer detection circuit 102 detects the color signal output from the Y/C separation circuit 101 and controls the monochrome/color changeover switches 7 and 13. Since there are color signals and monochrome signals, the recording operation for the color signals will be explained first.

The luminance signal input from 1 is converted into an FM signal by a frequency modulation circuit 5 after its high-frequency components are emphasized by a pre-emphasis circuit 4, and then band-limited by a high-pass filter 6 to be converted to black/white/black/white.
It enters the multiplication circuit 8 via the color changeover switch 7.

On the other hand, the color signals input from the 2nd and 3rd terminals are converted into a line sequential signal by the 1 color difference signal line sequentialization circuit 17.
It passes through a pre-emphasis circuit 16 that emphasizes high-frequency components, is converted into an FM signal in a lower frequency band than the luminance signal by a frequency modulation circuit 15, and is band-limited by a low-pass filter 14.
The signal is frequency-multiplexed with the luminance signal by the adder circuit 8 via the black-and-white/color changeover switch 13. The signal multiplexed at 8 corrects the low frequency modulated color signal by a low frequency equalizer 9, passes through a current amplifier 10, passes through an R/P changeover switch 11, and is recorded on a recording medium by a magnetic head 12.

Next, the operation of black and white recording signals will be explained. The luminance signal input from 1 passes through a pre-emphasis circuit 4, passes through a 1-frequency modulation circuit 5, passes through a monochrome/color changeover switch 7 without being subjected to band restriction, and enters an adder circuit 8. - The old color signal is cut off by the monochrome/color changeover switch 13 and is not added to the luminance signal. Therefore, only the luminance signal enters the low frequency equalizer 9, where the low frequency is corrected, and passes through the current amplifier 10 to the R/P cutoff. The data passes through the exchange switch 12 and is recorded on the recording medium by the magnetic head 11. The black-and-white/color changeover switch 7 may be switched manually, and if the color signal is input as a modulated carrier color signal as shown by the broken line in FIG. Automatic switching is also possible.

Next, the operation of the color reproduction signal will be explained. magnetic herad 1
The playback signal outputted at R/P switch 12
The signal passes through the preamplifier 18 and is corrected at the low frequency equalizer 19. The reproduced signal is passed through a high-pass filter 20 and a low-pass filter 25 to separate it into a luminance signal and a color signal. The luminance signal passes through a high-pass filter 20 and then passes through a black-and-white/color changeover switch 21, which inputs the color signal that has passed through a low-pass filter 25 to a black-and-white/color detection circuit 26, which detects whether it is black and white or color depending on the level of the color signal. It is controlled by Mute circuits 30 and 31 are also controlled by the monochrome/color detection circuit 26.

Now, the brightness signal that has passed through the switch 21 is sent to a brightness signal band equalizer 35 to emphasize the high range of the brightness signal, and then a frequency demodulation circuit 22 demodulates the frequency modulated signal, which is then filtered to a low-pass filter 2.
3, the signal is band-limited to remove unnecessary components, and is output to the luminance signal output terminal 32 via a de-emphasis circuit 24 that corrects pre-emphasis characteristics.

On the other hand, the chrominance signal passes through a low-pass filter 25, a frequency demodulation circuit 27, a de-emphasis circuit 28, and a synchronization circuit 29, where line-sequential chrominance signal synchronization is input, and a mute circuit 30, 31, and then a chrominance signal output terminal. Output on 33.34.

Next, the operation of the monochrome reproduction signal will be explained. magnetic herad 11
The reproduced signal output from the R7P switch 12 passes through the preamplifier 18 and is corrected for low frequency by the low frequency equalizer 19. Then, by using the monochrome/color changeover switch 21 controlled by the monochrome/color detection circuit 26, the signal is not passed through a high-pass filter and is not band-limited, but is passed through a frequency demodulation circuit 22, and is band-limited by a low-pass filter 23 to remove unnecessary components. The signal passes through the de-emphasis circuit 24 and is output to the luminance signal output terminal 32.

- Since the old color signal is not recorded in black and white, noise is demodulated. Therefore, the black and white/color detection circuit 26
The mute circuits 30 and 31 controlled by the color signal output terminals 33 and 34 are operated to prevent signals from being output to the color signal output terminals 33 and 34.

Figure 2 shows the head output frequency characteristics during black and white recording.
40 is the head output characteristic of black and white recording using the conventional circuit; 41
is the head output characteristic of monochrome recording according to the present invention. Conventionally, there is no low-frequency equalizer for luminance signals (as shown in head output characteristics 40 for monochrome recording using the conventional circuit, the low-frequency head output is small). Therefore, by placing the low frequency equalizer 9 after the adder circuit 8 as shown in FIG. 1, the low frequency range of the luminance signal during monochrome recording can be corrected, and the head output characteristic 41 during monochrome recording according to the present invention shown in FIG. 2 can be corrected. Frequency characteristics can be improved because the low range can be lifted.

FIG. 3 shows the frequency characteristics from the adding circuit for the luminance signal and chrominance signal to the recording amplifier during conventional recording, and the frequency characteristics of the luminance signal and chrominance signal input to the adding circuit. Reference numeral 45 indicates a frequency characteristic including the summation circuit for the luminance signal and color signal to the recording amplifier.

46 is the frequency characteristic of the luminance signal during black and white recording which is input to the addition circuit. Reference numeral 47 indicates the frequency characteristic of the luminance signal at the time of color signal recording which is input to the adding circuit. 48 is the frequency characteristic of the color signal input to the adding circuit during color signal recording. Frequency characteristics from adder circuit to recording amplifier 45
(Input voltage vs. recording current) is flat, and the frequency characteristic 48 of the color signal input to the adder circuit is corrected so that the low frequency equalizer is installed before the adder circuit, so that the color signal is raised in low frequency. Therefore, the output of the head is also corrected in the low range, but when recording black and white, only the color signal before the addition circuit has a low range equalizer, so the signal that does not go through the high pass filter 6 (shown in 46) is Frequency characteristic)
Even if you add a, the bandwidth cannot be extended to the low range, and if you try to extend the bandwidth to the low range, you must also install a low range equalizer on the luminance signal side before the adder circuit, which causes the circuit to become Make it complicated.

FIG. 4 shows the frequency characteristics from the adding circuit to the recording amplifier during recording according to the present invention, and the frequency characteristics of the luminance signal and chrominance signal input to the adding circuit.

50 is the low frequency equalizer 9 and current amplifier 10 shown in FIG.
This is the frequency characteristic that combines the Reference numeral 51 indicates the frequency characteristic of the luminance signal during color recording which is input to the addition circuit 8 shown in FIG. Reference numeral 52 indicates the frequency characteristic of the color signal during color recording which is input to the addition circuit 8 shown in FIG. 53 is the first
It is input to the 110 arithmetic circuit 8 shown in the figure. This is the frequency characteristic of the luminance signal during black and white recording.

When the circuit of the present invention is used to record a color signal, the luminance signal passes through a high-pass filter, so the low-frequency equalizer has no effect and the frequency characteristics are the same as conventional ones. Furthermore, for color signals, conventionally there is a low-frequency equalizer before the addition circuit for the luminance signal and color signal, and in the present invention there is a low-frequency equalizer after the addition circuit, but the input frequency characteristics to the head are the same as before. Therefore, the same performance as before can be obtained. When recording black-and-white signals, conventionally, the low-frequency equalizer was only provided on the color signal side before the addition circuit for the luminance signal and color signal, so the luminance signal was converted into a low-frequency component at the head output, as shown in Figure 2, 40. However, in the present invention, by placing an equalizer for the recording special low range after the luminance signal and chrominance signal addition circuit, the low range of the luminance signal can also be extended to the low range. As shown in 41, since the characteristics of the magnetic recording and reproducing system can be corrected, the frequency characteristics of the luminance signal can be improved without adding any special correction circuit.

Next, the setting of the frequency characteristics of the recording low-frequency equalizer circuit will be explained. Conventionally, the output characteristics of the head deteriorate in the low range, so the aim was to simply emphasize the low range, but the present invention aims to emphasize the low range without degrading the S/N of the color signal band. Playback of upper and lower sidebands in the band S
The characteristics of the recording system are set so that /N is approximately equal.

FIG. 5 shows the frequency characteristics of the head output signal and noise without correction, and the characteristics of the recording amplifier whose frequency characteristics have been corrected according to the present invention. Reference numeral 60 indicates a head output signal without correction, 61 indicates head output noise, and 62 indicates the respective frequency characteristics of the recording current subjected to frequency characteristic correction by the low-frequency equalizer according to the present invention. Reference numeral 62 in FIG. 5 is set to have a monotonically decreasing frequency characteristic so that the S/N of the upper and lower side bands of the reproduced FM color signal is approximately equal in the color signal band.

Next, the settings of the low-frequency equalizer circuit for the reproduction system will be explained. I mentioned above about the settings of the low-frequency equalizer in the recording system, but when you play back a signal that has been frequency-characterized by the low-frequency equalizer during recording, the S/N of the upper and lower sidebands of the color signal is almost equal, but the levels are not necessarily equal. In general, the noise emitted from the medium has a characteristic in which the high frequency range rises, similar to the signal.

The low-frequency equalizer in the reproduction system has a characteristic of making the upper and lower levels of the sidebands of the reproduced color signal almost equal (the noise level is also almost equal), and supplies this signal to the demodulation circuit.

FIG. 6 shows the playback head output characteristics of a signal recorded by correcting the frequency characteristics using the low frequency equalizer according to the present invention and the playback head output characteristics obtained by conventional correction. 63 is the head reproduction output of the signal according to the present invention, 64 is the noise output, and 65 is the frequency characteristic of the head output of the conventional signal.

FIG. 7 shows the frequency characteristics of the color signal band of the signal and noise output from the low frequency equalizer shown in FIG. 19.

66 is the frequency characteristic of the modulation frequency signal in the color signal band, and 67 is the frequency characteristic of the noise in the color signal band. In the head output, as shown in Figure 6, the levels of the upper and lower sidebands (J-, , J+1) are different, but the S/N of the upper and lower sidebands (J-, /N-1゜J◆l/N◆1 )
are equal. The input of the demodulation circuit is as shown in Figure 7.
The S/N ratios of the upper and lower sidebands are approximately equal, and the levels of the sidebands are also approximately equal.

Therefore, the S/N of the sideband itself is also improved.

Moreover, since the upper and lower sidebands and noise can be supplied to the demodulation circuit at approximately the same level, the S/N of the demodulated output can be improved.

In this embodiment, an example in which a color signal is recorded using an FM signal has been described, but the above concept can also be applied to a low frequency conversion recording method of a home VTR.

FIG. 8 is a circuit diagram of a specific recording system. 70 is a luminance signal input terminal, 71 is a high-pass filter 72, 77 is a monochrome/color changeover switch, 73 is a low-frequency equalizer 74 is a luminance signal and color signal addition circuit, 75 is a color signal input terminal,
76 is a low-pass filter; 78 is an output terminal for multiplexing the luminance signal and color signal; 79 is a luminance signal frequency modulation circuit; 80
is a color signal frequency modulation circuit, and 81.82 is a control signal input terminal of a changeover switch.

The present invention can be realized by adding 72, 77 black/white/power 4 color changeover switches to the conventional circuit in the recording system, and placing the low frequency equalizer after the adder circuit as shown in Figure 8, and the circuit is simple. .

During color recording, the selector switch 72 is turned on and one end of the high-pass filter 71 is grounded to form a high-pass filter, but during black-and-white recording, the selector switch 72 is turned off and opened, so that the band is not limited.

Similarly, the selector switch 77 is turned off during color recording and turned on during black-and-white recording, so that the color signal is short-circuited by the large-capacity capacitor C during black-and-white recording, and no voltage is generated. During monochrome recording, the oscillation of the modulation circuit 80 may be stopped to eliminate color signals.

〔Effect of the invention〕

According to the present invention, the color signal can be corrected during color recording, and the low range of the luminance signal can be corrected during monochrome recording, so that the frequency characteristics during monochrome recording can be improved without any particular cost increase. Furthermore, since it is possible to correct recording and reproduction with emphasis on S/N, it is also effective in improving S/N.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention. Fig. 2 is a frequency characteristic graph of the head output showing the effect of the low-frequency equalizer during recording, Fig. 3 is a graph showing the frequency characteristics of the conventional frequency modulation signal and recording amplifier, and Fig. 4 is a graph showing the frequency characteristics of the conventional frequency modulation signal and the recording amplifier. Graph showing the frequency characteristics of a frequency modulated signal and a recording amplifier. FIG. 5 is a graph showing the output of the head and the frequency characteristics of the recording amplifier corrected according to the present invention, and FIG. FIG. 7 is a graph showing the frequency characteristics of the color signal band corrected according to the present invention, and FIG. 8 is a circuit diagram showing a specific circuit example of the embodiment of the present invention. 1... Luminance signal input terminal, 2, 3... Color signal input terminal, 6, 20... High pass filter, 7, 13, 21
...Black and white/color changeover switch, 8...Addition circuit, 9, 19;...Low frequency equalizer, 14, 23, 25
...Low pass filter, 26...Black and white/color detection circuit, 30.31...Mute circuit, 33.34...
・Color signal output terminal. Figure 2 Figure 3 Figure 4 Figure 5 Diagram at the foot of Figure Figure 7

Claims (1)

[Claims] 1. Magnetic recording by frequency-multiplexing a frequency-modulated luminance signal and a chrominance signal placed in the low range of the modulated luminance signal, flattening the recording current frequency characteristic of the luminance signal band. In the recording and reproducing apparatus, a high-pass filter that passes the modulated luminance signal, a low-pass filter that passes the low frequency-converted color signal, and two signals input from a first input side and a second input side, respectively. When the adder circuit that adds (frequency multiplexes) and outputs the resultant video signal that generates the luminance signal and color signal is a color signal,
The modulated luminance signal after passing through the high-pass filter is introduced into a first input side of the adder circuit, and when the video signal is a monochrome signal, the modulated luminance signal before passing through the high-pass filter is introduced into the first input side of the addition circuit. a first switch for switching a signal path so as to lead it to a first input side of an adder circuit; and similarly, when the video signal is a color signal, the color signal after passing through the low-pass filter is connected to the adder circuit; a second switch that cuts off the signal path so that the color signal is not input to the second input side of the adder circuit when the video signal is a black and white signal; A magnetic recording and reproducing apparatus characterized by comprising: an equalizer connected to the output side of the adder circuit and emphasizing the low range of the low frequency-converted color signal included in the output. 2. In the magnetic recording and reproducing apparatus according to claim 1, the frequency characteristic of the equalizer is set to a monotonically decreasing frequency characteristic, and the S of the upper and lower side bands of the reproduced FM color signal is
1. A magnetic recording/reproducing device characterized in that /N is approximately equal.