JPH08182016A - Magnetic recording and reproducing device provided with fm equalizer circuit - Google Patents

Abstract

PURPOSE: To attain optimum frequency characteristic for a reproduced FM luminance signal with respect to the plural recording modes for the NTSC/PAL systems, plural tape speeds and different luminance signal bands. CONSTITUTION: A reproduction FM luminance signal is fed to a trap 4 and a subtractor 5 via a subtractor 3. An output of the subtractor 5 indicates a BPF characteristic and outputted from an output terminal 2 via an adder 9. An output of the trap 4 is negatively fed back to the subtractor 3 via a coefficient circuit 6 to make the frequency band characteristic narrow thereby increasing FM equalization quantity. Furthermore, the output of the trap is fed to the adder 9 via the coefficient circuit 7 and a low-pass filter 8 to reduce the FM equalization quantity thereby realizing the FM equalizer circuit with a large variable range with respect to the frequency characteristic.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to video signal processing of a video tape recorder, and more particularly to a magnetic recording / reproducing apparatus having an FM equalizing circuit for correcting the frequency characteristic of a reproduced FM signal.

[0002]

2. Description of the Related Art Household video tape recorders (hereinafter referred to as V
(Hereinafter referred to as TR), an FM-modulated luminance signal and a low-frequency-converted color signal are frequency-multiplexed and recorded on a magnetic tape, and at the time of reproduction, an FM luminance from a signal reproduced from a magnetic head is reproduced. After being separated into a signal and a low-pass conversion color signal, they are each processed and output.

In the reproduced FM luminance signal, side bands become unbalanced in the upper and lower sides due to the effect of lower side band enhancement that occurs in the process of recording and reproducing, and therefore an FM equalization circuit for correcting this is required. The FM equalization circuit includes a passive type circuit including a capacitor, a coil, and a resistor, and a cosine filter type using a delay element. A typical FM equalization circuit using a cosine filter is
For example, there is one disclosed in JP-A-62-248108. According to this, it is possible to obtain a reproduced image with good waveform reproducibility by detecting the state of the signal during reproduction and changing the frequency characteristic of FM equalization.

Further, when the reproduced FM luminance signal is lowered due to demagnetization of the magnetic tape, spacing loss, etc., the carrier component and the upper sideband component are lowered relative to the lower sideband component and the inversion phenomenon (vibration phenomenon) occurs. ) Occurs. In order to prevent such an inversion phenomenon, an inversion prevention circuit as disclosed in Japanese Patent Laid-Open No. 1-158813 has been devised. JP-A-1
The technique disclosed in Japanese Patent No. 158813 is composed of an FM equalizer circuit using a cosine filter and an inversion prevention circuit, and can be demodulated into a video signal in an FM demodulation circuit in a state in which the inversion phenomenon is prevented. .

[0005]

However, the configuration of the cosine filter shown in the conventional example has a drawback that the degree of freedom for changing the characteristic with respect to the FM equalization characteristic is small. The cosine filter has a peak frequency of 1 / 2τ and a zero output frequency of 0, 1 / τ, where τ is the delay time of the delay element.
Therefore, the characteristic becomes vertically symmetrical with respect to the peak frequency.
On the other hand, as the FM equalization characteristic used in the VTR, the peak amount and the frequency characteristic are different depending on the VTR different from the standard such as the VHS (registered trademark) standard and the 8 mm video standard. There is a problem that both parties cannot cope unless the degree of freedom is large. JP 62-2
The one disclosed in Japanese Patent No. 48108 has some degree of freedom with respect to changes in the amount of peak, but does not have the degree of freedom with respect to peak frequency characteristics. JP-A-1-
Similarly, in the conventional technique disclosed in Japanese Patent No. 158813, the FM equalizer circuit does not have the degree of freedom with respect to the peak frequency characteristic.

In a domestic VTR such as VHS standard and 8 mm video standard, a standard mode in which a luminance signal band is a signal band equal to or lower than a color subcarrier frequency during recording, and a luminance signal band is a color subcarrier frequency. There is a wideband mode having the above signal band. Since the carrier frequency of the FM luminance signal is different between the standard mode and the wideband mode, it is necessary to make the FM equalization characteristic optimal for each of the standard mode and the wideband mode. That is, in a wide band mode in which the carrier frequency of the FM luminance signal is high, the peak frequency of the FM equalization characteristic must be set higher than in the standard mode. However, it is not taken into consideration in the above-mentioned conventional technique, and there is a problem that it cannot be dealt with.

Further, in order to support the above-mentioned various standards by using a cosine filter, it is necessary to make the delay time of the delay element largely changeable, but two sets of delay elements having different delay times are provided. Alternatively, when integrated in an LSI, there is a problem that the number of elements used increases and the cost increases. For example, in a VHS type VTR aiming at low cost, there arises a problem that the cost increases when the above LSI is used.

The object of the present invention is to solve the above problems.
An object of the present invention is to provide a reproducing FM equalization circuit which can be applied to various VTRs and has good cost performance and suitable for LSI.

[0009]

In order to achieve the above object, the present invention provides a helical scan type magnetic recording in which a frequency multiplexed signal of an FM luminance signal and a low frequency conversion color signal is recorded and reproduced on a magnetic tape. In the reproducing device, a frequency dividing means for frequency-dividing the reproduced FM luminance signal into a first signal component and a second signal component, and the first signal component obtained by the frequency dividing means are passed through a first coefficient circuit. Means for returning to the input of the frequency dividing means, and a second signal obtained by the frequency dividing means for the first signal component obtained by the frequency dividing means via a second coefficient circuit and a band limiting circuit. A magnetic recording / reproducing apparatus including an FM equalization circuit having means for adding to a signal component, wherein the frequency division means improves the degree of freedom with respect to frequency characteristics in the FM equalization circuit. By controlling the coefficient circuit and the second coefficient circuit to improve the degree of freedom with respect to the change in the amount of peak in the FM equalizer circuit, the frequency characteristic of the reproduced FM luminance signal is set to a predetermined characteristic. It is composed.

Further, there is provided means for discriminating the tape feed speed for reproduction, and at least one of the first coefficient circuit and the second coefficient circuit is controlled by using the signal for discriminating the tape feed speed. Thus, the frequency characteristic of the reproduced FM luminance signal is set to a predetermined characteristic according to the tape feed speed.

Further, there is a detecting means for detecting the level of the reproduced FM luminance signal, and at least one of the first coefficient circuit and the second coefficient circuit is controlled by using the signal of which the level is detected, thereby preventing inversion. The circuit is configured so that the frequency characteristic of the reproduced FM luminance signal has a predetermined characteristic.

Further, a reversal prevention circuit is constituted by providing a limiter circuit for limiting the amplitude to the means for feeding back the first signal component to the input of the frequency dividing means via the first coefficient circuit, thereby forming the reproduction FM. The frequency characteristic of the luminance signal is configured to have a predetermined characteristic.

Further, in a magnetic recording / reproducing apparatus of a helical scan type having a standard mode and a wide band mode, for recording / reproducing a frequency multiplexed signal of an FM luminance signal and a low frequency conversion color signal on a magnetic tape. A frequency division means and a first coefficient circuit having means for discriminating a mode at the time of recording from the difference in carrier frequency of the reproduced FM luminance signal and using the means for discriminating the mode at the recording. At least one of the second coefficient circuit and the band limiting circuit is controlled, and the frequency characteristic of the reproduced FM luminance signal is set to a predetermined characteristic.

Further, the recorded signal is, for example, N.
The recording mode has means for discriminating a recording mode such as a TSC system signal or a PAL system signal.
Means for discriminating the frequency of at least one of the frequency dividing means, the first coefficient circuit, the second coefficient circuit, and the band limiting circuit, and the frequency characteristic of the reproduced FM luminance signal has a predetermined characteristic. It is configured to.

[0015]

According to the present invention, with the above-described structure, the reproduced FM luminance signal acts to correct the phenomenon that the sideband becomes unbalanced due to the enhancement effect of the lower sideband generated in the process of recording and reproducing, and the inversion phenomenon. Is reduced and a good reproduction signal can be obtained.

Further, there is provided means for discriminating the tape feed speed for reproduction, and at least one of the first coefficient circuit and the second coefficient circuit is controlled by using the signal for discriminating the tape feed speed. With this structure, the FM equalization characteristic is optimized according to the level of the reproduced FM luminance signal.
It operates so that the frequency characteristic of the M luminance signal becomes a predetermined characteristic.

Further, there is provided a detecting means for detecting the level of the reproduced FM luminance signal, and at least one of the first coefficient circuit and the second coefficient circuit is controlled by using the level-detected signal. Thus, it operates so as to have the optimum FM equalization characteristic according to the level of the reproduction FM luminance signal, and the reproduction F
It operates so that the frequency characteristic of the M luminance signal becomes a predetermined characteristic.

Further, by providing a limiter circuit for limiting the amplitude to the means for feeding back the first signal component to the input of the frequency dividing means via the first coefficient circuit, the reproduced FM luminance signal can be obtained. It operates so as to have the optimum FM equalization characteristic according to the level, and operates so as to have the frequency characteristic of the reproduced FM luminance signal as a predetermined characteristic.

Furthermore, a magnetic recording / reproducing apparatus of a helical scan type having a standard mode and a wide band mode for recording / reproducing a frequency multiplex signal of an FM luminance signal and a low frequency conversion color signal on a magnetic tape. In the reproduction FM, the reproduction FM luminance signal acts to discriminate the mode at the time of recording from the difference in the carrier frequency and set the optimum FM equalization characteristic for each of the standard mode and the wide band mode. It operates so that the frequency characteristic of the luminance signal becomes a predetermined characteristic.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of an FM equalization circuit according to the present invention. In this embodiment, a reproduction F
A trap 4 and a subtractor 5 are provided as frequency dividing means for frequency-dividing the M luminance signal into a first signal component and a second signal component.
It is composed of. Reference numeral 1 is an input terminal of a reproduced FM luminance signal, 2 is an output terminal of an FM equalization circuit, 3 and 5 are subtractors, 4
Is a trap, 6 and 7 are coefficient circuits, 8 is an LPF (low-pass filter), and 9 is an adder. The reproduced FM luminance signal input from the input terminal 1 is supplied to the trap 4 and the subtractor 5 via the subtractor 3. The resonance frequency of the trap 4 is set to f ₀
Then, the output of the subtractor 5 is the BPF whose center frequency is f ₀ .
It has a characteristic of (band pass filter) and is output to the output terminal 2 of the FM equalization circuit through the adder 9. On the other hand, the output of the trap 4 is fed back to the subtractor 3 via the coefficient circuit 6 and is also supplied to the adder 9 via the coefficient circuit 7 and the LPF 8.

The characteristics obtained by the coefficient circuit 6 will be described with reference to FIG. FIG. 2 shows an example of characteristics obtained by the output of the subtractor 5 with respect to the value of the coefficient K1 of the coefficient circuit 6.
By configuring the negative feedback for the input signal by using the subtractor 3, it is possible to obtain a narrow band characteristic as shown in FIG. 2 as the coefficient K1 of the coefficient circuit 6 is increased. In this way, the narrow band characteristic is realized by increasing the coefficient K1 of the coefficient circuit 6.

Next, the characteristics obtained by the coefficient circuit 7 will be described with reference to FIG. FIG. 3 shows the characteristic obtained by the output of the adder 9 with respect to the value of the coefficient K2 of the coefficient circuit 7. As an example, the characteristic when the coefficient K1 of the coefficient circuit 6 is 0 is shown. By configuring the LPF 8 to add only the low-frequency component, the response of the low-frequency component of the center frequency f ₀ changes as the coefficient K2 of the coefficient circuit 7 changes, and the degree of freedom as the frequency characteristic of the FM equalizer circuit is increased. Can be expanded.

Further, since only the low frequency component can be raised with respect to the center frequency f _0, F which causes carrier leak in a state where the frequency characteristic after FM demodulation is secured.
It is possible to suppress the second-order distortion component of the M carrier.

As described above, since the characteristics of the FM equalizer circuit can be freely set by changing the coefficients K1 and K2 of the coefficient circuits 6 and 7, using the same FM equalizer circuit, for example, It is possible to support both a VHS type magnetic recording / reproducing apparatus and an 8 mm type magnetic recording / reproducing apparatus having different standards. Therefore, when the FM equalization circuit circuit is integrated in the LSI, the FM equalization circuit circuit can be adopted in both types of the magnetic recording / reproducing apparatus described above, so that the cost of the LSI can be reduced by the effect of mass production.

FIG. 4 is a block diagram showing a second embodiment of the FM equalization circuit according to the present invention. In this embodiment, the reproduction F
A BPF 10 and a subtractor 1 are used as frequency dividing means for frequency-dividing the M luminance signal into a first signal component and a second signal component.
It is composed of 1. The same parts as those in the embodiment shown in FIG. 1 are designated by the same reference numerals. The reproduced FM luminance signal input from the input terminal 1 is supplied to the BPF 10 and the subtractor 11 via the subtractor 3, and assuming that the center frequency of the BPF 10 is f ₀ , the output of the subtractor 11 is a trap whose resonance frequency is f ₀ . It becomes the characteristic of. Therefore, the coefficient circuits 6 and 7 and the adder 9
The signal supplied to can obtain the same characteristics as the configuration of the embodiment shown in FIG. As described above, even if the BPF 10 and the subtracter 11 are used as the frequency dividing means for frequency-dividing the reproduced FM luminance signal into the first signal component and the second signal component, the FM equalization similar to that of the first embodiment is performed. The characteristics of the circuit can be obtained.

Next, a third embodiment of the present invention is shown in FIG. A standard recording mode is used for the tape feed speed of a home VTR.
There are a mode (hereinafter referred to as SP mode) and a long-time recording mode (hereinafter referred to as LP mode). The feedback coefficient and the addition coefficient are reproduced in the VTR as compared with the embodiment of FIG. The configuration is such that switching is performed according to the tape feed speed. 12, 1
3 is a feedback coefficient circuit, 15 and 16 are addition coefficient circuits, 1
4, 17 are switch circuits, 18 is SP mode / LP mode
This is an input terminal for inputting a mode determination signal of a mode, and is otherwise the same as that of the embodiment of FIG. Generally, in the LP mode having a slow reproduction speed, the recording density is lowered and the reproduction S /
As N decreases, the inversion margin becomes smaller than in SP mode. From the input terminal 18 to SP mode / LP mode
Signal is input. Therefore, in the SP mode, the feedback coefficient K1 (given by the coefficient circuit 12) and the LP mode are used.
The relation with the feedback coefficient K1 '(given by the coefficient circuit 13) in the mode is selected to be K1≤K1', and the inversion margin is increased by setting the narrower band characteristic in the LP mode.
Also, the addition coefficient K2 in the SP mode (coefficient circuit 1
5) and the addition coefficient K2 in the LP mode.
′ (Given by the coefficient circuit 16) is expressed as K2 ≧ K2
It is possible to improve the frequency characteristic after FM demodulation by emphasizing the lower sideband by selecting low as' and raising the lower frequency in SP mode.

As described above, according to this embodiment, V
Since the coefficient value for feedback and the coefficient value for addition can be set according to the tape speed for reproduction in TR, it is possible to realize the optimum FM equalization characteristic for each mode.

Next, a fourth embodiment of the present invention will be described with reference to FIG. The embodiment shown in FIG. 6 has a configuration in which there is a degree of freedom in setting the feedback coefficient and the addition coefficient, and is the same as the embodiment shown in FIG. 1 except for the voltage control amplifiers 21, 22, and the control signal input terminals 23, 24. They are the same and are denoted by the same reference numerals. The feedback coefficient and the addition coefficient are changed by the voltage control amplifiers 21 and 22. For example, as the control voltage input from the control signal input terminal 23 increases, the gain of the voltage control amplifier 21 increases, the feedback coefficient increases, and narrow band characteristics can be realized. In addition, the control signal input terminal 24
The gain of the voltage control amplifier 22 increases and the addition coefficient increases as the control voltage input from the circuit increases, and the low-frequency pass band can be extended.

As described above, according to the present embodiment, by forming the feedback coefficient circuit and the addition coefficient circuit by the voltage control amplifier, it is possible to greatly improve the degree of freedom of the FM equalization characteristic.

Next, a fifth embodiment of the present invention will be described with reference to FIG. This is obtained by replacing the feedback coefficient circuit 6 in the embodiment of FIG. 1 with a limiter circuit 32 for limiting the amplitude and an attenuator 31. By inserting the limiter circuit 32 in the feedback loop, the feedback coefficient becomes small when a large amplitude is input to realize a wide band characteristic, and when the small amplitude input is made, a feedback coefficient becomes large and a narrow band characteristic is realized. That is, the magnetic tape
This function works to suppress the reversal phenomenon that occurs when the reproduced FM luminance signal is lowered due to demagnetization of the magnetic field or spacing loss. FIG. 8 shows a characteristic example of the embodiment shown in FIG. As the input signal decreases to 0 dB, -10 dB, -20 dB, and -30 dB, a narrow band characteristic is exhibited, and at -30 dB or less, the characteristic becomes constant.

As described above, according to the present embodiment, by providing the limiter in the feedback coefficient circuit, V
It is possible to improve the inversion margin during TR reproduction.

Next, a sixth embodiment of the present invention will be described with reference to FIG. FIG. 9 shows a reproduction luminance signal processing circuit of a VTR incorporating the FM equalization circuit shown in FIG. 40 is a magnetic tape, 41 is a magnetic head, 42 is a regenerative amplifier, 34 is an FM equalizing circuit, and 43 is an AGC circuit (auto.
gain controller), 44 is an FM demodulation circuit, 45 is a reproduction luminance signal processing circuit, 46 is a luminance signal output terminal, 35 is an reproduced FM luminance signal envelope detection circuit, and 36
Is a full-wave rectification circuit, 37 is a detection circuit, and 38 and 39 are voltage conversion circuits. In this embodiment, the envelope of the reproduced FM signal is detected, and when the envelope is large, the FM equalizer circuit is controlled so as to have a wide band characteristic.
When the gain is small, the inversion margin is expanded by controlling the FM equalizer circuit to have a narrow band characteristic. That is, the output signal of the voltage conversion circuit 38 is input to the terminal 23 to control the feedback coefficient, and the voltage conversion circuit 3
The output signal of 9 is input to the terminal 24 to control the coefficient of addition. The characteristics of the voltage conversion circuit 38 with respect to the reproduced signal level of the FM luminance signal are shown by 47 in FIG. 10, and the characteristics of the voltage conversion circuit 39 are shown by 48 in FIG. 4 of FIG.
As shown in FIG. 7, when the reproduction signal level decreases, the output voltage of the voltage conversion circuit 38 increases, and the gain of the voltage control amplifier 21 shown in FIG. Control. Further, as indicated by 48 in FIG. 10, when the reproduction signal level increases, the voltage conversion circuit 3
The output voltage of 9 becomes high, and the gain of the voltage control amplifier 22 shown in FIG. 6 is increased to control the FM equalization circuit 34 to a wide band characteristic.

As described above, according to the present embodiment, the envelope of the reproduced FM signal is detected and the feedback coefficient and the addition coefficient are controlled. Can be improved.

Next, a seventh embodiment of the present invention will be described with reference to FIGS. 11, 12 and 13. Generally, the VHS standard,
In a domestic VTR such as an 8 mm video standard, a standard mode in which a luminance signal band is a signal band equal to or lower than a color subcarrier frequency and a wideband mode in which a luminance signal band is a signal band equal to or higher than a color subcarrier frequency are used for recording. -There is a de. The frequency spectrum of the FM luminance signal recorded on the magnetic tape is the frequency spectrum 52 in the standard mode and the frequency spectrum 53 in the wide band mode, as shown in FIG. The carrier frequency is set higher in the wideband mode than in the wideband mode. The carrier frequencies f _AS and f _AW of the frequency spectrum 52 of the FM luminance signal are carrier frequencies at the sync signal tip and the 100% white level of the luminance signal, respectively, and carrier frequencies f _BS and f of the frequency spectrum 53 are the same. _BW is the carrier frequency at the sync signal tip of the luminance signal and 100% white level, respectively. For example,
The carrier frequency f _AS in the standard mode is 3.4 MHz and the f _AW is 4.4 MHz, and the carrier frequency f _BS in the wide band mode.
Is 5.4 MHz and f _BW is 7.0 MHz. As described above, since the carrier frequency of the FM luminance signal is different between the standard mode and the wideband mode, the FM equalization characteristic is 5 in the standard mode.
4 and, in the wideband mode, the FM equalization characteristic needs to be 55.

FIG. 11 is a block diagram showing an embodiment of the FM equalizer circuit according to the present invention, which corresponds to the above-mentioned standard mode and wide band mode. In this embodiment, the FM equalizer circuit has a peak. It has the same degree of freedom as the setting of the frequency, and is the same as the embodiment shown in FIG. 1 except for the trap 50, the voltage controlled amplifiers 21, 22, and the control signal input terminals 51, 23, 24, and the same symbols are given. Write down. The peak frequency, the feedback coefficient, and the addition coefficient are respectively set to the control signal input terminal 51,
It is changed by control signals from 23 and 24. For example, as the control voltage input from the control signal input terminal 51 becomes higher, the resonance frequency of the trap becomes higher and the peak frequency of the FM equalization characteristic can be made higher. Further, as the control voltage input from the control signal input terminal 23 increases, the gain of the voltage control amplifier 21 increases, the coefficient of feedback increases, and narrow band characteristics can be realized. Further, as the control voltage input from the control signal input terminal 24 increases, the gain of the voltage control amplifier 22 increases, the addition coefficient increases, and the low-frequency pass band can be extended.

FIG. 13 shows a reproduction luminance signal processing circuit of a VTR in which the FM equalization circuit shown in FIG. 11 is incorporated. 40 is a magnetic tape, 41 is a magnetic head, 42 is a regenerative amplifier, 56 is an FM equalizing circuit, 43 is an AGC circuit,
44 is an FM demodulation circuit, 45 is a reproduction luminance signal processing circuit,
46 is a luminance signal output terminal, 57 is a recording mode discrimination circuit,
Reference numerals 58, 59 and 60 are voltage conversion circuits. In this embodiment,
The recording mode discriminating circuit 57 discriminates between the standard mode and the wide band mode based on the difference in carrier frequency of the reproduced FM luminance signal, and the characteristics of the FM equalizing circuit in the standard mode and the wide band mode. It is configured to switch. By setting the voltage output from the voltage conversion circuit 59 in the wideband mode higher than the voltage output from the voltage conversion circuit 59 in the wideband mode, the peak frequency of the FM equalization characteristic is set. Can be higher. Further, by setting the voltage output from the voltage conversion circuit 58 in the standard mode and the wide band mode, respectively,
The gain of the voltage control amplifier 21 can be optimally set, that is, the feedback coefficient can be optimally set. Furthermore, the standard mode
By setting the voltage output from the voltage conversion circuit 60 in the wide mode and the wide band mode, respectively, the gain of the voltage control amplifier 22 can be set optimally, that is, the addition coefficient can be set optimally.

In the above description, the recording mode discriminating circuit 57 discriminates the standard mode or the wide band mode from the difference in the carrier frequency of the reproduced FM luminance signal. The circuit 57 may be configured to determine a television signal system such as an NTSC system television signal or a PAL system television signal, and to switch the characteristics of the FM equalization circuit according to the television signal system.

As described above, according to the present embodiment, the recording mode is discriminated and the peak frequency of the FM equalizer circuit and the feedback coefficient and addition coefficient are controlled.
The FM equalization characteristic can be optimized for each of the standard mode and the wideband mode.

Next, an eighth embodiment of the present invention will be described with reference to FIG. The embodiment shown in FIG. 14 shows a reproduction luminance signal processing circuit of a VTR incorporating the FM equalization circuit shown in FIG. 11, which is a recording mode for discriminating between a standard mode and a wide band mode. The FM equalization circuit is controlled by using the drive discrimination signal and the reproduction tape feed velocity discrimination signal. 40 is a magnetic tape, 41 is a magnetic head, 42 is a regenerative amplifier, 56 is an FM equalizing circuit, 43 is an AGC circuit, 4
4 is an FM demodulation circuit, 45 is a reproduction luminance signal processing circuit, 4
6 is a luminance signal output terminal, 57 is a recording mode discrimination circuit, 6
Reference numeral 1 is a tape feed speed discrimination circuit, and 62, 63 and 64 are voltage conversion circuits. The recording mode discriminating circuit 57 discriminates between the standard mode and the wide band mode based on the difference in the carrier frequency of the reproduced FM luminance signal, and the F mode is selected in the standard mode and the wide band mode.
Switches the characteristics of the M equalization circuit. By setting the voltage output from the voltage conversion circuit 59 in the wideband mode higher than the voltage output from the voltage conversion circuit 59 in the wideband mode, the peak frequency of the FM equalization characteristic is set. Can be higher. Further, the gain of the voltage control amplifier 21 is optimized, that is, the feedback is achieved by setting the voltage output from the voltage conversion circuit 62 in the standard mode and the wide band mode and the SP mode and the LP mode, respectively. The coefficient of can be optimally set. Further, the voltage output from the voltage conversion circuit 64 is set in the standard mode and the wide band mode, and in the SP mode and the LP mode, respectively.
Can be optimally set, that is, the addition coefficient can be optimally set.

As described above, according to the present embodiment, the recording mode and the tape feed speed are discriminated and the peak frequency of the FM equalizer circuit and the feedback coefficient and addition coefficient are controlled. With the configuration, SP mode of standard mode and wideband mode
The FM and LP modes can have optimum FM equalization characteristics for each.

Next, a ninth embodiment of the present invention will be described with reference to FIG. The embodiment shown in FIG. 15 shows a configuration example in which the FM equalization circuit shown in FIG. 11 is integrated in an LSI. In FIG. 15, 70 is an LSI, 71,
72 and 73 are LSI pins, 74 is an inductor, 75,
76 is a capacitor, 68, 69, 77 to 82 are resistors, 8
3 to 85 are switches, and 86 is a control signal input terminal.
Inductor 74 and capacitor 75 and capacitor 75
Constitutes a trap, and the resonance frequency of the trap can be switched by the control signal of the control signal input terminal 86 and the switch 84 which are provided as necessary. Further, the feedback coefficient value is set by the resistors 77 and 78 and the voltage control amplifier 21, and the feedback coefficient value can be switched by the control signal of the control signal input terminal 86 and the switch 83 which are provided as necessary. Further, the addition coefficient value is set by the resistors 80 and 81 and the voltage control amplifier 22, and the addition coefficient value can be switched by the control signal of the control signal input terminal 86 and the switch 85 which are provided as necessary. For example, in a VTR having a standard mode and a wide band mode, the output signal of the recording mode discriminating circuit is used as the control signal of the control signal input terminal 86 so that the standard mode and the wide band mode are used. Each can have the optimum FM equalization characteristic. In a VTR having only standard mode,
Only inductor 72 pin and inductor 74 and capacitor 7
A desired FM equalization characteristic can be obtained only by arranging 5.

Next, FIG. 16 shows an example of characteristics of the resonance of the trap with respect to Q in the embodiment shown in FIG. FIG.
As shown in 5, when a trap is externally attached, a resistor 6
The Q of the single trap composed of 9, the inductor 74, and the capacitors 75 and 76 has a great influence on the overall characteristics of the FM equalization circuit. That is, if the Q of the trap is set too high, the amplification degree of the voltage controlled amplifier 21 is minimized (that is, K1 = 0).
However, the Q of the circuit becomes high, and it becomes impossible to match the desired characteristics with the voltage control amplifier 21. Also,
On the contrary, if the Q of the trap is too small, the voltage controlled amplifier 2
Even if the amplification factor of 1 is set to the maximum (twice the normal setting), the Q of the circuit is too lower than the desired Q, and it becomes impossible to adjust the voltage controlled amplifier 21. In FIG. 16, the value of the coefficient K1 of the feedback coefficient circuit is set to 0.5 and the value of the coefficient K2 of the addition coefficient circuit is set to 0.5, and the resonance Q of the trap is set to 0.5, 1, 2, and 3. It is a characteristic when it is done. As a result of examining reproduction FM equalization characteristics in the current VHS standard VTR and 8 mm standard VTR, the inventors have found that in order to obtain desired characteristics with the voltage controlled amplifiers 21 and 22 having the configuration shown in FIG. The Q of the trap (consisting of the resistor 69, the inductor 74, the capacitors 75 and 76) alone is 0.5 ≦ Q ≦ 2
I found that it should be set between. In contrast to the external trap configuration of FIG. 15, when the trap 50 is incorporated in the LSI as shown in FIG. 11, it is necessary to fix it to a certain characteristic in advance, and set the Q of the trap within the range of 0.5 ≦ Q ≦ 2. Good. In the embodiments shown in FIGS. 11 and 15, ideally, when the Q of the trap is set to a value of around 1, the degree of freedom in setting the characteristics by the voltage controlled amplifiers 21 and 22 increases.

As described above, the Q of the resonance of the trap
Is set between 0.5 and 2, and the coefficient K of the feedback coefficient circuit is set.
A desired FM equalization characteristic can be obtained by setting the value of 1 and the value of the coefficient K2 of the addition coefficient circuit according to the required characteristics.

[0045]

As described above, according to the present embodiment, the FM equalization characteristic can be freely set by the peripheral parts of the LSI while minimizing the circuit scale to be integrated in the LSI.

In addition, the SP mode / LP mode etc.
Even in a VTR having a plurality of modes such as a standard feed rate mode and a wide band mode as a signal band of a luminance signal and a feed rate and a television signal system such as an NTSC system / PAL system, an FM equalization characteristic is obtained. , The peak frequency, the feedback coefficient, and the addition coefficient can be set according to the mode, so that the optimum FM equalization characteristic can be obtained in each mode and the S / N waveform is good. A reproduced signal with good reproducibility can be obtained.

Furthermore, by using the same FM equalization circuit circuit, it is possible to support both a VHS type magnetic recording / reproducing apparatus and an 8 mm type magnetic recording / reproducing apparatus of different standards. Therefore, when the FM equalization circuit circuit is integrated in an LSI, it can be adopted in both types of the magnetic recording / reproducing apparatus described above, and there is also an effect that the LSI cost can be further reduced by the mass production effect.

[Brief description of drawings]

FIG. 1 is a block diagram of an FM equalization circuit showing an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing frequency characteristics of an FM equalization circuit according to the present invention.

FIG. 3 is a characteristic diagram showing frequency characteristics of an FM equalization circuit according to the present invention.

FIG. 4 is a block diagram of an FM equalization circuit showing an embodiment of the present invention.

FIG. 5 is a block diagram of an FM equalization circuit showing an embodiment of the present invention.

FIG. 6 is a block diagram of an FM equalization circuit showing an embodiment of the present invention.

FIG. 7 is a block diagram of an FM equalization circuit showing an embodiment of the present invention.

FIG. 8 is a characteristic diagram showing frequency characteristics of the FM equalization circuit according to the present invention.

FIG. 9 is a block diagram of reproduction luminance signal processing of a magnetic recording / reproducing apparatus including an FM equalization circuit according to an embodiment of the present invention.

FIG. 10 is a characteristic diagram showing envelope detection characteristics according to the present invention.

FIG. 11 is a block diagram of an FM equalization circuit showing an embodiment of the present invention.

FIG. 12: F in standard mode and wide band mode according to the present invention
The figure which shows the frequency characteristic of M brightness | luminance signal.

FIG. 13 is a block diagram of reproduction luminance signal processing of a magnetic recording / reproducing apparatus including an FM equalization circuit according to another embodiment of the present invention.

FIG. 14 is a block diagram of reproduction luminance signal processing of a magnetic recording / reproducing apparatus including an FM equalizing circuit according to still another embodiment of the present invention.

FIG. 15 is a block diagram of an FM equalization circuit showing an embodiment of the present invention.

FIG. 16 is a characteristic diagram showing frequency characteristics of the FM equalization circuit according to the present invention.

[Explanation of symbols]

3, 5, 11 ... Subtractor, 9 ... Adder, 4 ... Trap, 6, 7, 12, 13, 15, 16 ... Coefficient circuit, 8 ...
.... Low-pass filters, 10 ... band-pass filters 21, 22 ... Voltage-controlled amplifiers, 31 ... Attenuators, 32 ...
-Limiter, 35 ... Envelope detection circuit, 36 ... Full-wave rectification circuit, 37 ... Detection circuit, 38, 39, 58, 5
9, 60, 62, 63, 64 ... Voltage conversion circuit, 57 ...
Recording mode discrimination circuit, 61 ... Tape feed speed discrimination circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kawamura et al. 1410 Inada, Hitachinaka City, Ibaraki Prefecture Hitachi, Ltd. Personal Media Equipment Division (72) Inventor Yukiya Ueki 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa (72) Inventor Hideo Nishijima, 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Stock Company, Hitachi, Ltd.

Claims (11)

[Claims] 1. A frequency dividing means for frequency-dividing a reproduced FM luminance signal into a first signal component and a second signal component, and a first coefficient circuit for converting the first signal component obtained by the frequency dividing means into a first coefficient circuit. Means for returning to the input of the frequency division means via the second signal circuit obtained by the frequency division means via the second coefficient circuit and the band limiting circuit for the first signal component obtained by the frequency division means. A magnetic recording / reproducing apparatus having an FM equalization circuit, which is configured to add a frequency component of a reproduced FM luminance signal to a predetermined characteristic by adding an output signal to the signal component of 1. 2. A helical scan type magnetic recording / reproducing apparatus for recording / reproducing a frequency-multiplexed signal of an FM luminance signal and a low-frequency converted color signal on a magnetic tape, and a tape for discriminating a tape feeding speed for reproduction. Feed rate discriminating circuit, frequency dividing means for frequency-dividing the reproduced FM luminance signal into a first signal component and a second signal component, and a first coefficient for the first signal component obtained by the frequency dividing means. Means for returning to the input of the frequency dividing means via a circuit, and the first signal component obtained by the frequency dividing means is obtained by the frequency dividing means via a second coefficient circuit and a band limiting circuit. A reproduction FM brightness is provided by controlling the at least one of the first coefficient circuit and the second coefficient circuit by using means for adding to the second signal component and using the output of the tape feed speed discrimination circuit. Signal circumference Magnetic recording and reproducing apparatus including an FM equalizer circuit, characterized in that the number characteristic to a predetermined characteristic. 3. A detection circuit for detecting the level of a reproduced FM luminance signal in a helical scan type magnetic recording / reproducing apparatus for recording / reproducing a frequency multiplexed signal of an FM luminance signal and a low frequency conversion color signal on a magnetic tape. A frequency dividing means for frequency-dividing the reproduced FM luminance signal into a first signal component and a second signal component, and the first signal component obtained by the frequency dividing means is passed through the first coefficient circuit to the frequency Means for returning to the input of the dividing means, and the first signal component obtained by the frequency dividing means into a second signal component obtained by the frequency dividing means via a second coefficient circuit and a band limiting circuit. By using the output of the detection circuit that has a means for adding and that detects the level of the reproduction FM luminance signal, and controls at least one of the first coefficient circuit and the second coefficient circuit, the reproduction FM brightness is increased. Magnetic recording and reproducing apparatus including an FM equalizer circuit, characterized in that the frequency characteristic of the signal to a predetermined characteristic. 4. A standard mode in which a frequency-multiplexed signal of an FM luminance signal and a low-frequency conversion chrominance signal has a carrier frequency band of the luminance signal as a signal band equal to or lower than a color sub-carrier frequency, and a carrier frequency band of the luminance signal. In a helical scan type magnetic recording / reproducing apparatus for recording / reproducing on / from a magnetic tape by any one of a recording mode with a wide band mode having a signal band higher than a color sub-carrier frequency. Means for discriminating the mode at the time of recording from the difference in frequency, frequency dividing means for frequency-dividing the reproduced FM luminance signal into a first signal component and a second signal component, and a frequency dividing means A means for returning one signal component to the input of the frequency dividing means via a first coefficient circuit, and a first signal component obtained by the frequency dividing means via a second coefficient circuit and a band limiting circuit. Lap The frequency division means, the first coefficient circuit, and the second coefficient are provided by means for adding to the second signal component obtained by the number division means, and for determining the mode at the time of recording. A magnetic recording / reproducing apparatus equipped with an FM equalization circuit, which controls a frequency characteristic of a reproduced FM luminance signal by controlling at least one of a circuit and a band limiting circuit. A magnetic recording / reproducing apparatus having an FM equalizing circuit characterized by the above. 5. The frequency dividing means according to claim 1, 2, 3 or 4, comprising a trap and a subtraction circuit, a reproduced FM luminance signal is input to the trap, and an output signal of the trap is the first signal. In addition to the signal component, the first signal component that is the output signal of the trap is reproduced FM
A magnetic recording / reproducing apparatus provided with an FM equalization circuit, wherein the second signal component is obtained by subtracting from the luminance signal by the subtraction circuit. 6. The frequency dividing means according to claim 1, 2, 3 or 4, comprising a bandpass filter and a subtraction circuit, wherein a reproduced FM luminance signal is input to the bandpass filter and output from the bandpass filter. A signal is used as the second signal component, and the second signal component that is the output signal of the bandpass filter is subtracted from the reproduced FM luminance signal by the subtraction circuit to obtain the first signal component. A magnetic recording / reproducing apparatus provided with an FM equalization circuit. 7. The first switching means for switching the coefficient of the first coefficient circuit to at least two values, and the coefficient of the second coefficient circuit of at least 2. A magnetic recording / reproducing apparatus provided with an FM equalization circuit, comprising: a second switching means for switching to a different value. 8. The coefficient of the first coefficient circuit is formed of a first voltage controlled amplifier, and the second coefficient circuit is formed of a second voltage controlled amplifier according to claim 1, 2, 3, or 4. A magnetic recording / reproducing apparatus having an FM equalizing circuit characterized by the above. 9. The detector according to claim 3, wherein the coefficient of the first coefficient circuit comprises a first voltage control amplifier, the second coefficient circuit comprises a second voltage control amplifier, and A magnetic recording / reproducing apparatus having an FM equalization circuit, wherein the gain of the first voltage-controlled amplifier is increased and the gain of the second voltage-controlled amplifier is decreased as the output level decreases. 10. A magnetic recording / reproducing apparatus having an FM equalizing circuit according to claim 1, wherein the first coefficient circuit is composed of a limiter circuit and an attenuator. 11. The frequency division means according to claim 1, 2, 3 or 4, comprising a trap and a subtraction circuit, a reproduction FM luminance signal is input to the trap, and an output signal of the trap is the first signal. In addition to the signal component, the first signal component that is the output signal of the trap is reproduced FM
The second signal component is obtained by subtracting the luminance signal from the subtraction circuit, and the Q of the resonance of the trap is obtained.
Is set between 0.5 and 2, and the coefficient of the first coefficient circuit and the coefficient of the second coefficient circuit are set between 0 and 1, and the like. Magnetic recording / reproducing apparatus equipped with a digitizing circuit.