JPS61148993A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To cope with the difference of a frequency allocation of signal by means of a simple constitution by changing, in accordance with the allocation of the signal, the characteristic of the circuit elements of a circuit of which characteristic is dependent on the input signal. CONSTITUTION:The 2 kinds of circuit elements provided corresponding to the frequency allocation in the luminance signal system are, for instance, LPFs 14 and 75 which limit the band of the luminance signal from a Y/C separating circuit 13. The LPF75 is one for high-band recording system of which cutoff frequency is set about 4MHz. Selecting between the LPFs 14 and 75 is achieved by switches 76 and 77. On the other hand, as to the chrominance signal system, the frequency band of the chrominance-signal output of the circuit 13 is limited. The elements, for instance, are LPFs 21 and 86. The passband of the LPF86 is set at 3.58MHz-1MHz-3.85+500kHz. selection between the LPFs 21 and 86 is achieved by switches 88 and 89. The switches are controlled by the control signal SC supplied from a terminal 78.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a video tape recorder (hereinafter referred to as VT), for example.
The present invention relates to a magnetic recording/reproducing device such as the following.

[Technical background of the invention]

Currently, the method used in home VTRs is TEHA, β
There are various systems, such as the VH8 system and the V-2000 system, but these systems basically employ the color under system for frequency allocation. This color under one-way system separates a standard color video signal into a luminance signal and a color signal, and records the luminance signal directly on a magnetic tape as a low carrier FM signal. Regarding the one-color signal, this is frequency-converted to a low frequency band, and the low-carrier FM signal is used as an AC bias signal to be recorded on a magnetic tape by frequency multiplexing with this FM signal.

For example, if the standard color video signal is the NTSC system, β
In the method, the sync chip carrier frequency of the low carrier FM signal is 3.65 MHz, the 100% white carrier frequency is 4.8 MHz, and the FM frequency deviation is 1.2.
The MHz and FM bands used are approximately 4.4 to 12 MHz. Further, the center frequency of the color signal frequency-converted to a low frequency band is approximately 688 kHz, and its usage band is approximately ±500 kHz.

In addition, in the ■S method, the synchronization of the low carrier FM signal, f
Gear 9 frequency is 3.4 MHz, 100% white carrier frequency is 4.4 Fi'[Hz, FM frequency deviation is I MHz, FM usage band is 4.0±3.
It is about 1 MHz. Further, the center frequency of the color signal frequency-converted to a low frequency range is about 620 kHz, and its usage band is also about ±500 kHz.

Fig. 5 shows the so-called β-MI Fl 7ohm, t (in this case N
This figure shows the frequency allocation of the TSC system. Similarly, Figure 6 shows the VHS former.

The so-called ■5-HI which adopts the above recording method in
This shows the frequency allocation of the F17 automatic. In addition, in Figures 5 and 6, (YFM) is the low carrier wave F.
M signal (luminance signal), ((') is the color signal frequency-converted to low frequency, (AFM) is the audio FM signal. In the case of VH8 system, recording of the audio FM signal (AFM) is It uses a deep recording method.

Here, an outline of an electrical processing circuit for a standard color video signal of the NTSC system in a conventional VTR will be explained.

FIG. 7 is a circuit diagram showing a recording system circuit in a conventional NTSC (β format) VTR. Furthermore, this figure shows a recording system circuit in the most common VTR equipped with two rotary heads.

In the figure, a color video signal input from an input terminal 11 passes through an AGC circuit 12, and after its amplitude characteristics are corrected,
The η total separation circuit 13 separates the signal into a luminance signal and a color signal.

The luminance signal output from the y/c separation circuit 13 is input to a low-nos filter (LPF) 14 and subjected to a predetermined band restriction. The DC component of the output of the p-Noyas filter 14 is regenerated in a clamp circuit 15, and then the high frequency component is emphasized in a pre-emphasis circuit 16.

After this, the 4 ZHv foot circuit 17 performs slight increase/decrease processing on the DC voltage in order to shift the carrier frequency by half of the horizontal synchronization frequency (fH) for each field according to the switching pulse (SWP) that indicates the rotational phase of the head. receive. Thereafter, the signal is FM modulated by the FM modulation circuit 18 to become a low carrier FM signal. The output of the FM modulation circuit is input to an adder circuit 20 after attenuating components outside the required band by a high/4 filter HPF 19 .

On the other hand, the color signal outputted from the η-separator 13 is band-limited by a pantone filter (BPF) 21, and then its amplitude characteristics are corrected by an ACC circuit 22. 7. The color burst signal is enhanced in the assist circuit 23 (some systems do not include this circuit element 23).

The output of this burst en7 assist circuit 23 is the multiplication circuit 2
4 and frequency-converted using the output from the color synchronization system circuit 25. The color synchronization system circuit 25 generates a carrier signal for converting the frequency of the color signal to a lower frequency band in synchronization with a reference signal such as a horizontal synchronization signal or a color burst signal. The output of the multiplication circuit 24 is the low/base filter 2
After components outside the required band are attenuated in step 6, the addition circuit 20
and is added to the low carrier FM signal. Note that the low/base filter 26 has recording equivalent characteristics.

The output of the adder circuit 20 is divided into two parts, each of which has a recording amplifier f.
;TV,

Figure 8 shows the above conventional NTSC β format) VT
FIG. 3 is a circuit diagram showing a reproduction system circuit of R. - In the figure, the signals reproduced by the reproduction heads 41 and 42 pass through the four-tally drive transformer 43゜4゛4 and the preamp f4s,
4t; is amplified to a predetermined level by the preamplifiers f45 and 4g, and then subjected to reproduction-equalization processing in reproduction equalization circuits 41 and 411. Reproduction equalization circuit 41.48
The output of is controlled by a switching noise (SWP) which indicates the rotational phase of doors 41 and 42.

The signal is made into a continuous signal by the switch.

High/quarter filter 50 extracts the low carrier FM signal from the output of switch 49. ) The output of the s ino and filter 50 is sent to the FMAGC circuit 51. After passing through the amplitude limiting circuit 52, the signal is demodulated by the FM demodulation circuit 53, and the color video signal is extracted by the row/yas filter 54. The output of this low-noise filter 54 is fed to a de-emphasis circuit 55.
After the high frequency components are suppressed, the DC voltage level corrected during recording is returned to the original level by the TfH return circuit 56. The output of this ifH return circuit 56 is Y<L type noise canceller circuit 51 and noise canceller circuit 5.
After being subjected to crosstalk removal and normal noise reduction at step 8, the signal is supplied to an adder circuit 59.

The selected output of the switch 49 is applied to the p4 filter 0 (roughly, low), and the color signal frequency-converted to the low frequency range is extracted. After the amplitude characteristics of the output of the Ronogus Filter 0 are corrected in the ACC circuit 61, the color burst signal emphasized during recording is suppressed in the burst de-emphasis circuit 62. The output of the burst de-emphasis circuit 62 is multiplied by the output of the color synchronization circuit 64 in a multiplication circuit 63. This results in
The color signal that has been frequency-converted to a lower frequency band is returned to its original frequency band. Here, the color synchronization system circuit 64 generates a carrier signal for frequency conversion based on a reproduced horizontal synchronization signal, a reproduced color burst signal, a reference fixed oscillator output, etc. The output of the multiplication circuit 63 is given to the trap circuit 65,
Frequency conversion carrier signal component and low frequency frequency conversion signal component
color signal components are removed. The output of the trap circuit 65 is passed through a color comb filter 66 to remove crosstalk components from adjacent traps, and then sent to the pantone mother filter 7.
At , the color signal whose frequency has been restored to its original value is extracted. The output of the noise filter 7 is applied to an adder circuit 59 via an auto-killer switch 68, where it is added to the luminance signal described above.

The output of the adder circuit 59 passes through the mute circuit 69 to the output stage 7.
0 and is led to the output terminal 11 as a color video signal with low impedance (75 Ω). Furthermore (MC
) is a mutecosy rule signal.

The above is a general description of conventional recording system and reproduction system signal processing circuits.

As mentioned above, the household V
In TR, regardless of the method, the low carrier wave F of the luminance signal
The frequency band of the M signal is ±3 around the carrier frequency.
The horizontal resolution is approximately MHs, and the horizontal resolution is per field.
There are 230 to 250 twins in effective horizontal scan lines. Also, the frequency band of the color signal is 158MH3±50
It is about 0kHz. Therefore, it is difficult to obtain high-quality reproduced images using the method described above due to the limitations of these frequency formats. Furthermore, it is difficult to desire detailed reproduction of details in reproduced images.

Incidentally, in recent years, tapes with good short-wavelength recording characteristics have been prototyped, and, for example, barium- or ferrite-coated superimposed magnetized tapes have entered the practical stage. This tape has several orders of magnitude better short wavelength recording characteristics than conventional longitudinal recording tapes. Therefore, to fully bring out the performance of this tape, the FM carrier frequency of the low carrier FM signal.

It is possible to obtain a high-quality reproduced image by increasing the FM frequency shift, increasing the FM band used, or re-determining the center frequency, band used, and recording characteristics of the color signal frequency-converted to a lower frequency band.

[Problems with threat technology]

However, as mentioned above, with the advent of new magnetic tape,
Amid pressure to change the frequency allocation of signals, the penetration rate of ■1, which follows the conventional frequency allocation, has exceeded 20% in Japan, and moreover, The number of software tapes is also quite large.
:)-. Therefore, in the future, when manufacturing VTRs, it will be important to make the conventional frequency allocation system compatible with the new frequency allocation system.

[Purpose of the invention]

The present invention has been made in order to cope with the above-mentioned circumstances, and it is an object of the present invention to provide a magnetic recording and reproducing device that can cope with differences in signal frequency alignment with a simple configuration. Summary of the Invention The present invention is configured to switch the characteristics of a circuit element whose circuit characteristics depend on the frequency of an input signal in accordance with the frequency allocation of the signal.

[Embodiments of the Invention] Embodiments of the invention will now be described in detail with reference to the drawings.

1 and 2 show the configuration of an embodiment of the present invention, with FIG. 1 showing a recording system circuit and FIG. 2 showing a reproduction system circuit. In this embodiment, a case will be described as a representative case in which frequency allocation is set to fully bring out the performance of a conventional frequency allocation plate and barium and 7-elite coated perpendicular magnetic tape. The former method of recording and reproducing signals with a frequency of 74 and 40 degrees is generally referred to as a narrowband recording method, while the latter method of recording and reproducing signals with a frequency of 74 and 400 nm is called a wideband recording method (high band recording method). recording method).

Here, to briefly explain the latter frequency allocation, it is set as shown in FIG. 3, for example, in the NTSC system β-HIFi7 ohm. In other words, as the FM carrier frequency of the low carrier FM signal (YFM), the syn-edge lag carrier frequency is 5.8 MHz.
, 100% white carrier frequency is 7.0 MHz
, FM frequency deviation is 1.2 MHm, and 7M usage band is 6.6±40 Wms. In addition, the color signal is frequency-converted to a low frequency (the center frequency of Q is approximately 688 kHz).
z((44-fragrance) fH), its usage band is -500
kHz~+1 dish 2.

In addition, the NTSC system vH87# - Y y) "C
'GE is set as shown in FIG. 4, for example. That is, as the FM carrier frequency of the low carrier FM signal, the syn-edge lag carrier frequency is &OMHz, 100%.
White carrier frequency is aOMus, FM frequency deviation is LOMHz, 7M usage band is 4.35±40M
It is Hz. In addition, the color signal (0
The center frequency is approximately 625's (40 fH), and its operating band is -500 kHz to +IMus.

In the circuits shown in FIGS. 1 and 2, circuit elements whose circuit characteristics depend on the frequency of their input signals are
Two types are provided depending on the scene, and one of these can be selected depending on the frequency allocation of the recording or reproduction signal.

Here, first, the recording system circuit of the i-th WJ will be explained. In FIG. 1, the same parts as in FIG. 7 are given the same reference numerals.

In Fig. 1, two types of circuit elements are provided depending on the frequency allocation. First, in the luminance signal system, Y/
There is a Lono bus filter 14.75 that limits the band of the luminance signal output of the C separation circuit 13. Of these, the o/4 filter 15 is a 4-north filter for high band recording, and its power and frequency are set to about 40 b/Ex. The selection of these two arm-to-arm 5 filters 14 and 15 is achieved by the switches provided at their input and output ends.
Made by Chia 6.77. In addition, the selection of the Rounos filter by the switches 76 and 77 is carried out at the terminal 78.
This is done in accordance with the control signal (Sc) input from.

Similarly, there are pre-emphasis circuits that emphasize high-frequency components of luminance signals, FM modulation circuits that frequency-modulate luminance signals, and high-intensity filters that suppress components outside the required band of the modulated output. Here, the pre-emphasis circuit 79.
The FM modulation circuit eat high-pass filter 81 is provided for the bipant recording method. These times −
Switching between the circuit elements 19, 80.81 and the circuit element 16, 18, 19 for the conventional narrow band recording method is performed using the control signal (Be
) by switches 82, 83, 54, 86.

On the other hand, in the color signal system, there is a pantone filter 21.1117 that limits the band of the color signal output of the Y/C separation circuit 13. Among these, the pandonodus filter for high band recording method is 86 MHz and 58 MHz-1, OMHz ~
The passband is set to 9.58 hmz + 500 kHz. Similarly, a high-band recording type filter 81 is added to the Rounogus filter having recording equivalent characteristics. The breadth pass filters 21 and 86 are switched by switches 8B and 89 in accordance with the control signal (Ss), and the low pass filters 26 and 117 are also switched by switches 90 and 91 in accordance with the control signal (Sc).

Next, the reproduction system circuit will be explained using FIG.

Note that in FIG. 2, the same parts as in FIG. 8 are given the same reference numerals. In this circuit, two types of circuit elements are provided: first, a preamplifier that amplifies the reproduction output of the reproduction head 47, 42 to a required level, and a reproduction equalization circuit that reproduces and equalizes this preamplifier output. In the figure, reference numerals 92 and 93 are a reproduction amplifier, a reproduction equalization circuit, and a reproduction equalization circuit for the high-band recording system on the playback side, respectively, and 94.
Reference numerals 95 and 95 designate a reproduction amplifier, a reproduction equalization circuit, and a reproduction equalization circuit, respectively. In this case, the resonant frequency of the heads 41 and 42 is 9 to 10 Wmz, and the quality factor is the same as before.

Switching of the input side of the preamplifier and reproduction equalization circuit is inputted from the terminal 78. This is done by switches 96,97 according to control signals. The switching on the output side is performed by a switch 100 for the luminance signal and by a switch 109 for the chrominance signal, which will be described later. In addition, the switch 98 controlled by He, Dosui, Chingutsu and Rus (s'%1vP)
is a switch that changes the playback equalization output on the high band recording system side to a continuous signal.

A high-noise filter 99 for the high-band recording method is also provided as a high-noise filter for extracting a low carrier FM signal from the reproduced equalized output. Two types of high quality filters 50.
Switching of the output side of 99 is performed by a switch 100 in accordance with a control signal (Be). This low-carrier FM signal system further includes a low/4th filter that extracts a luminance signal from the output of the FM demodulation circuit 53, and a de-emphasis circuit that suppresses high-frequency components of the output of this Denosu filter.
There are also 2 noise cancellers for noise reduction.
The seed is set. Here, 101, 102, and 103 are a low Δ filter, a de-emphasis γ-cis circuit, and a noise reducer, respectively, for the high-band recording method. This is a main circuit. Switching of these circuit elements 101, 102, 103 and narrowband recording system circuit elements 54, 55, 511 is performed by a control signal (S
c) according to switch 104゜105.106,20
It is done by 7.

Regarding the color signal system, first, a filter 10B for the high band recording system is added as a filter for extracting color signals from the reproduction equalization 85. Switching between the output sides of the two types of filters 60 and 108 is performed by a switch 109 in accordance with a control signal (Sc). In this color signal system, a high band recording filter 110 is added as a pantone filter for extracting color signals from the output of the color comb filter 66. These 3,58 MH
Filter 67 with a passband of z ± 500 kHz and 3.58 MHz - 1,0 MHz N3.58 MHz
Filter 11 with a passband of +500 kHy.
0 is switched by the switch 11 according to the control signal (Sc).
1.112.

Note that the signal processing operations in FIGS. 1 and 2 are similar to those in the seventh section.
Since it is substantially the same as FIG. 8 and FIG. 8, its explanation will be omitted here.

As described in detail above, according to this embodiment, for circuit elements such as the low-pass filter 14 whose circuit characteristics depend on the input Hayabusa frequency, the characteristics for each frequency allocation, -With a very simple configuration such as providing two different types of circuits, the frequency a)-
Able to deal with differences between systems.

In the present invention, instead of separately forming two types of circuits with different characteristics, only two types of parts necessary for changing the characteristics may be provided, and the characteristics may be changed by switching these parts.

Further, the present invention is applicable not only to color video signals of the NTSC system but also to color video signals of the PAL and SECOM systems. Furthermore, the present invention is of course applicable to VTRs other than the β and VH8 formats.

〔Effect of the invention〕

As described above, according to this invention, it is possible to provide a magnetic recording and reproducing apparatus that can cope with a difference in frequency of 70 degrees with a simple configuration.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a recording system circuit according to an embodiment of the present invention, FIG. 2 is a circuit diagram similarly showing a reproduction system circuit, and FIG. 3 is a high-band recording system β-H1Fi 7-ohm frequency alignment. Figure 4 is a diagram showing the frequency allocation of the S format, and Figures 5 and 6 are narrowband recording format β-H1Fl 7 Ohm, VH8-HI Fi 7 #, respectively. -my ) (7
7 and 8 are circuit diagrams showing a recording system circuit and a reproduction system circuit, respectively, of a conventional VTR. 14.75, 26.8';/, 54,101°60.1
08... Rono parable filter, 16, 79... Pre-engineering circuit, III, 80... FM transition circuit 19
, 81.1oy... bypass filter, 21, 86.
6'i, 110...Band pass filter, 45.46
, 92.94... Noriamp, 47.4. It, 93
．． 95... Reproduction equalization circuit, 55°102...f4x
7-y cis circuit, 58, 103... Noise canceller, 76.77.82, 83° 84.85.8B, 89
,90,91,96°97.98,100,104,1
05,106゜J177.109,111,112...
·switch. Applicant's Representative Patent Attorney Takehiko Suzue Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] A magnetic recording/reproducing device characterized in that the characteristics of a circuit element whose circuit characteristics depend on the input signal frequency are switched in accordance with the frequency allocation of the signal.