JP2710868B2 - Magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus.

[0002]

2. Description of the Related Art FIG. 11 is a block circuit diagram of a video signal processing circuit in a reproducing system of a conventional magnetic recording / reproducing apparatus. A video signal recorded on a magnetic tape 1 is picked up by a head 2 and is read by a head amplifier 3. The signal is amplified and input to the luminance signal processing circuit 10 and the chroma signal processing circuit 4.
In the chroma signal processing circuit 4, 629kH _z ± 5
Chroma signal being converted into low-frequency signals 00KH _z is separated luminance FM signal at a low pass filter (LPF) 5, a low-frequency chroma signal separation converter 6
At converted chroma signal 3.58MH _z ± 500kH _z, is unwanted noise component in a band pass filter (BPF) 7 is removed at a comb filter 8 is cross-talk component is removed, to an amplifier 9 Then, the signal is synthesized by the synthesizing circuit 11 with the luminance signal output from the luminance signal processing circuit 10 and reproduced as a video signal 12.

[0003]

Bandpass filter and low-pass filter of the invention Problems to be Solved conventional chroma signal processing circuit has also corresponding to the phase change portion of the chroma signal, it is used as the wide pass <br/> bandwidth However, the chroma signal is originally of a single frequency, and only the phase difference with the burst signal needs to be identified, and the S / N is improved by narrowing the pass band width of the filter. However, in a color change portion, that is, in a phase change portion of a chroma signal, a frequency band is widened, so that a filter having a narrow pass bandwidth has poor color reproducibility at a color change. For this reason, a bandwidth necessary for passing the phase change portion is required, and there is a problem that the S / N of the chroma signal in portions other than the color change portion is deteriorated.

[0004] The present invention has been made to solve the above problems, good S / N in the portion where the color of the click Roma signal does not change, in the portion where the color of the click Roma signal changes It is an object of the present invention to obtain a magnetic recording / reproducing apparatus having good color reproducibility.

[0005]

SUMMARY OF THE INVENTION The present invention provides a low-frequency chroma signal.
This converter converts the signal to a chroma signal and outputs it.
Connected to the output side of the converter, a delay element by a predetermined amount delaying the chroma signal, compares the phases of the output and the upper Chrysanthemum B <br/> Ma signal of the delay element, the color change upon both the phase mismatch color change portion detection means and a phase detection circuit for generating a part detection signal, the color change section passband narrow <br/> have respectively connecting the wide filter with passband filter of the output side of the detection means and connected to the output side of the filter means and the filter means, switching <br/> grayed outputting switching the output from the wide <br/> have filter passband and output from a narrow filter with passband comprising means, when the color change section detecting means generates a color change portion detection signal passband from the switching means
To generate output from the wide filters, when the color change portion detection signal is not generated, is obtained so as to generate an output from the narrow filters passing <br/> over bandwidth from said switching means.

The present invention also provides a filter having a narrow pass band.
It has a filter with a wide pass band,
Filter means for inputting a range chroma signal, this filter
From the filter with a narrow passband connected to the output of the means
Between the output of the filter and the output from a filter with a wide passband
Switching means for outputting
Connects to the output side and converts low-band chroma signals to chroma signals
Converter and the output side of this converter
A delay element connected to delay the chroma signal by a predetermined amount
And the phase between the output of this delay element and the chroma signal
Generates a color change detection signal when the two phases do not match.
A color detection unit having a phase detection circuit;
When the color change portion detection means generates a color change portion detection signal,
From the above switching means From a filter with a wide pass band
And the above color change portion detection signal is not generated
At the time, a filter with a narrow pass band is
This is to generate an output from the data .

[0007]

According to the present invention, the portion in which the color of the click Roma signal does not change, the chroma signal S / N is improved since through a narrow filter passband width. Further, since the portion where the color changes passes through a filter having a wide pass band, the color reproducibility is improved.

[0008]

FIG. 1 is a block circuit diagram showing one embodiment of the present invention. In this figure, 20 is a color change portion detection circuit, a delay element (DL) 21, formed of a phase detection circuit 22, click Loma input signal S1, 1Myuse delay elements 21
Delayed by about c. On the other hand, the output S2 of the delay element 21 and
Fine click Loma input signal S1 is input to the phase detection circuit 22. The phase detection circuit 22 is composed of a multiplier or the like,
The phase of the two input signals S1 and S2 is compared, and a color change portion detection signal S3 in which a portion having a different phase is significant is output.

[0009] Figure 2 is the timing chart for explaining the operation of the phase detection circuit 22, the phase of the click Loma input signal S1, 31a portion of the phase change portion 32 as a boundary and 31b
The part is different. Also, the chroma delay signal S2
Is delayed by about 1 μsec by the delay element 21 and 33 of S2
a and the phase of the portion 31a of S1 and S
The phase of the portion 31b of S1 and the phase of the portion 33b of S2 are the same. The color change portion detection signal S3 output from the phase detection circuit 22 is a signal that is significant during a period in which the phases of the change points 32 to 34 do not match.

[0010] click Roma signal S2 which has passed through the delay element 21
Is input to the band-pass filters 7a and 7b. Bandpass filter 7a has a narrow pass band width shown by a broken line in FIG. 3, the band-pass filter 7b is wide pass band width shown by the solid line in FIG. 3 3.58MH _z ± 500
It has kH _z. Reference numeral 25 denotes a switching element, which is switched by a color change portion detection signal S3. That is, in a portion where the color does not change, the band-pass filter 7a is selected, unnecessary noise components are removed, and the S / N is improved. In the part where the color changes, the band-pass filter 7b is selected and the information of the hue change part is passed without loss, so that the color reproducibility is ensured.

The "operation delay time of the switching element 25" shown in FIG. 2 indicates the timing at which the switching element 25 operates, and the delay with respect to the signal of S3 is based on the operation delay of the switching element 25. Zuzuku.

FIG. 4 is a block circuit diagram showing another embodiment of the present invention, in which two LPFs 5a and 5b having different bandwidths connected to the input side of a converter 6 are switched by a color change portion detection signal S3. It was made. In this figure, 5a is a narrow band low-pass filter, and 5b is a wide band low-pass filter, each having a band characteristic as shown in FIG.

As described above, the wider the band of the low-pass filter, the more accurately the hue change portion is reproduced. However, if the band is too wide, a luminance FM signal enters and the S / N becomes worse or interference occurs. For this reason, the broadband low-pass filter 5b
Has a pass band of 1.2 MHz as shown by the solid line in FIG. 5, and in the color change portion of the chroma signal, from the narrow band shown by the broken line 5a in FIG.
By switching to a wide band such as b, the color reproducibility of the chroma signal is secured.

In this case, the color change portion detection signal S3 is 3.5.
Since it is created from the 8 MHz baseband chroma signal, it does not match in time as it is. Therefore, a chroma demodulation circuit may be separately provided to adjust the shift of the switching time, and the color change portion detection signal is converted from the chroma signal delayed by a time (about 63.5 μsec) corresponding to one horizontal scanning period. The time may be adjusted by creating S3. This is based on the assumption that in the television signal, the video signal one line before and the current video signal have substantially the same information.

FIG. 6 is a block circuit diagram showing still another embodiment of the present invention. In the figure, the chroma signal S4 at the time of recording to the VTR, 3.58MH _z ± 500kH _z
This signal is converted by the converter 6 into a low-band chroma signal S5. FIG. 7 is a signal waveform diagram of this embodiment. FIG. 7A shows a low-band chroma signal S5, and FIG.
0 is a low-frequency converted burst signal. Here, the same chroma signal S5 will be described for easy understanding.

The color change portion detection signal S3 output from the color change portion detection circuit 20 is output at the timing shown in FIG. Since the color change portion detection signal S3 is input to the base of the transistor 45 to turn on the transistor 45, the emitter resistor of the transistor 43 has a small value during the period when the color change portion detection signal S3 is significant, and As shown in FIG. 7B, the output S6 of 47 has its waveform rising and falling emphasized.

This waveform-enhanced low-band chroma signal S6
Is mixed with the luminance FM signal by the synthesizing circuit 48 and is recorded on the magnetic tape 1 by the magnetic head 2 via the recording amplifier 50. When the hue change portion of the chroma signal is emphasized and recorded as in this embodiment, deterioration of the rise of the chroma signal at the time of reproduction can be improved.

FIG. 8 is a block circuit diagram showing another embodiment of the present invention, which improves the rise of a chroma signal during reproduction. As shown in FIG. 9A, the rising of the chroma signal S7 output from the comb filter 8 has been reduced due to the process of recording and reproduction of the VTR. In the present embodiment, the transistors 61 and 62 are operated at the timing of the color change portion detection signal S3, whereby the signal shown in FIG.
Chroma output signal S whose rising is improved as shown in FIG.
8 have been obtained.

FIG. 10 is a block circuit diagram showing still another embodiment of the present invention, which shows a reproduction system of a luminance signal in a VTR. A luminance FM signal picked up from a magnetic tape 1 by a magnetic head 2 is , Is amplified by the head amplifier 3 and demodulated by the FM demodulation circuit 83 to become a video signal.
After de-emphasis is performed by 2, unnecessary noise is removed through a low-pass filter 85.

The luminance signal that has passed through the low-pass filter 85 is output through a noise canceller circuit 86. The noise cancellation level in the noise canceller circuit 86 is determined by the capacitances C3 and C4. As for the capacitances C1 and C2 of the de-emphasis circuit 84 and the capacitances C3 and C4 of the noise canceller circuit 86 described above, the S / N of the luminance video signal is improved as the value is larger, but the waveform is weaker.

In this embodiment, a hue change portion of a video signal
That is, attention is paid to the fact that the color change also changes in synchronization with the luminance signal, and the effect of the de-emphasis circuit 84 and the noise canceller circuit 86 is determined at the timing of the color change portion detection signal S3 output from the color change portion detection circuit 20. By lowering the luminance signal at the color change,
The reproduction image of the TR is improved. The color change portion detection signal S3 is input to the bases of the transistors 40 and 43 via the inverter 91,
Reference numeral 43 indicates that the capacitors C2 and C4 are disconnected from the de-emphasis circuit 84 and the noise canceller circuit 86 only when the color change portion detection signal S3 is significant, that is, when the color changes.

Although the effects of both the de-emphasis circuit 84 and the noise canceller circuit 86 are reduced in the embodiment of FIG. 10, either one of them may be used.

[0023]

According to the present invention, a click Roma signal by comparing the phases of the signal obtained by delaying this signal, detects a portion where the color of the click <br/> Roma signal changes, this to improve color change portion detection signal S3 passed through a filter having a wide frequency band portion but only click Loma signals that color reproducibility, no partial color change portion detection signal S3, a filter having a narrow frequency band Since the noise is suppressed by passing the signal to improve the S / N, there is an effect that the color reproducibility and the S / N can be improved.

[Brief description of the drawings]

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

FIG. 2 is a signal waveform diagram of each part of the embodiment of FIG.

FIG. 3 is a characteristic diagram of the bandpass filter of the embodiment of FIG.

FIG. 4 is a block circuit diagram showing another embodiment of the present invention.

FIG. 5 is a characteristic diagram of the low-pass filter of the embodiment of FIG.

FIG. 6 is a block circuit diagram showing still another embodiment of the present invention.

FIG. 7 is a signal waveform diagram of each part of the embodiment of FIG.

FIG. 8 is a block circuit diagram showing another embodiment of the present invention.

9 is a signal waveform diagram of each part of the embodiment of FIG.

FIG. 10 is a block circuit diagram showing still another embodiment of the present invention.

FIG. 11 is a block circuit diagram showing a conventional magnetic recording / reproducing apparatus.

[Explanation of symbols]

 Reference Signs List 4 Chroma signal processing circuit 5, 5a, 5b Low-pass filter 6 Converter 7, 7a, 7b Band-pass filter 8 Comb-type filter 10 Luminance signal processing circuit 20 Color change section detection circuit 21 Delay element 22 Phase detection circuit 84 De-emphasis circuit 86 Noise cancellation Sera circuit

Claims (2)

(57) [Claims] A low-band chroma signal is converted into a chroma signal.
Output converter, connected to the output side of this converter
It is, compares the delay element by a predetermined amount delaying the chroma signal, the phase of the output and the upper Chrysanthemum Roma signal of the delay element,
Color change portion detection means having at both phase mismatch and a phase detection circuit for generating a color change portion detection signal, Guang passband narrow filter with passband at the output side of the color change section detecting unit <br / > There is connected to the output side of the filter means and this Fi <br/> filter means and respectively connected to a filter, narrow passband filter
A switching means for switching and outputting outputs from the wide filter having passband and output from, the color change section
When the detection means has generated the color change portion detection signal, the output from the wide filter having passband from said switching means
Raises, when the color change portion detection signal is not generated, from the narrow filters passband from said switching means
A magnetic recording / reproducing apparatus characterized in that an output is generated . 2. A filter having a narrow pass band and a wide pass band.
And a low-pass chroma signal
Filter means to which is input, the output side of this filter means
Output from a filter with a narrow pass band
A switch that switches and outputs the output from a wide-band filter.
Switching means, connected to the output side of this switching means
And converts the low-band chroma signal to a chroma signal and outputs it.
Connected to the converter and the output side of this converter,
A delay element for delaying the chroma signal by a predetermined amount;
Compare the phases of the output of the element and the chroma signal, and
Phase detection circuit that generates a color change section detection signal when the colors do not match
And a color change portion detecting means having the following.
When the means generates a color change portion detection signal, the switch
Output from a filter with a wide pass band
When the color change portion detection signal is not generated,
Output from a filter with a narrow passband from the switching means
A magnetic recording / reproducing apparatus characterized in that a magnetic field is generated .