JPH01279695A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To compensate the deterioration of reproduced chrominance signal reproduced from a magnetic tape by high-frequency-converting the reproduced chrominance signal, demodulating the converted reproduced chrominance signal to a color difference signal, further waveform-shaping the obtained color difference signal, modulating the waveform-shaped color difference signal to the chrominance signal, mixing the chrominance signal in a demodulated reproduced luminance signal, and outputting the mixed signal. CONSTITUTION:The structure of a magnetic recording and reproducing device 21 is made into the one in which the reproduced chrominance signal reproduced from a magnetic tape 9 is high-frequency-converted and demodulated to the color difference signal at a decoder 22, and the obtained color difference signal is waveform-shaped by adding a two-dimensional differential form at a waveform shaping circuit 23, modulated to the chrominance signal at an encoder 24 next to the waveform shaping circuit 23, mixed in the demodulated reproduced luminance signal, and outputted. Thus, high-frequency compensation can be attained, which takes one step into a signal waveform itself, a deteriorated waveform to be the cause of bleeding can be compensated through waveform-shaping, and the bleeding can be removed from a reproduced picture by high-frequency converting the reproduced chrominance signal, once demodulating the high-frequency concerted reproduced chrominance signal to the color difference signal as a baseband signal, and executing contour emphasizing processing in a time-domain instread of high-frequency converting the reproduced chrominance signal and immediately adding the high-frequency converted reproduced chrominance signal to the demodulated luminance signal.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a magnetic recording and reproducing device that eliminates color fringing from reproduced images by demodulating reproduced color signals into color difference signals and shaping the waveforms. .

[Prior Art] A magnetic recording/reproducing apparatus 1 shown in FIG. 4 is of a type that performs frequency multiplex recording of a frequency modulated luminance signal and a low frequency conversion color signal.

During signal recording, the luminance signal separated by the luminance/color separation circuit 2 is frequency-modulated by the FM modulation circuit 3, and after low-frequency conversion by the low-frequency conversion circuit 4, high-frequency emphasis is applied by the pre-emphasis circuit 5. The color signals are mixed by an adder 6 and recorded on a magnetic tape 9 via a changeover switch 7 and a magnetic head 8.

Furthermore, during signal reproduction, the luminance signal separated by the luminance/color separation circuit 10 is demodulated by the FM demodulation circuit II, and after the de-emphasis circuit 12 cancels the high-frequency emphasis, the high-frequency conversion circuit 13 converts the luminance signal to the original value. The color signals frequency-converted into the signal band are mixed by an adder I4 and output as a reproduced video signal.

In the case of the VHS system, the low frequency conversion color signal has an occupied band of approximately 500 kT-1y on both sides of its center frequency of 629 kHz, and as shown in Figure 5, the frequency modulated luminance The lower limit of the band of the lower sideband of the signal or the occupied band of the recorded color signal are in contact with each other. In this example, in view of these circumstances, the color signal 4F5 is used during recording so that the color signal, especially the high frequency component, recorded in a narrow recording band that can be said to be the minimum for practical use does not deteriorate during the recording and reproduction process. This circuit is equipped with a Brienfanos circuit 5 that emphasizes the sieve area component of the signal, and has the same aim as similar processing performed on the recorded luminance signal.

[Problems to be Solved by the Invention] The above-mentioned conventional magnetic recording/reproducing device I emphasizes the sub-region components of the recorded color signal in the frequency domain. A slight peak is formed at the shoulder of the occupied band of the wave, but when viewed in the time domain, this peak in the frequency distribution also has a slight edge at the rise or fall of the color difference signal, which is the baseband signal of the color signal. For color signals that are only emphasized and are expected to deteriorate during the recording and playback process, there is still room for improvement, as countermeasures against deterioration that go into the signal waveform itself in the time domain. Ta.

[Means for Solving the Problems] The present invention solves the above-mentioned problems, and provides a method for converting a low frequency converted color signal reproduced from a magnetic tape on which a frequency modulated luminance signal and a low frequency converted color signal are frequency multiplexed. A decoder that is connected to a high-frequency conversion circuit that performs high-frequency conversion and demodulates a color signal into a color difference signal, a waveform shaping circuit that shapes the waveform of the color difference signal demodulated by this decoder in the time domain, and The present invention is characterized in that it includes an encoder that modulates the shaped color difference signal into a color signal and mixes it with the demodulated reproduced luminance signal.

[Operations] This invention uses a reproduced color signal reproduced from a magnetic tape,
After high-frequency conversion, demodulation into a color difference signal, waveform shaping of the obtained color difference signal, modulation into a color signal, mixing with the demodulated reproduced luminance signal, and outputting the waveform of the color difference signal in the time domain. Aims to compensate for deterioration of reproduced color signals through shaping.

[Embodiments] Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a circuit diagram showing an embodiment of the magnetic recording/reproducing device of the present invention, and FIGS. 2 and 3 are a circuit diagram of the waveform shaping circuit shown in FIG. 1 and a signal waveform diagram of each part of the circuit, respectively. be.

In FIG. 1, the magnetic recording/reproducing device 21 demodulates the high frequency converted color signal into two color difference signals of red and blue between the high frequency conversion circuit 13 of the color signal reproduction system and the adder I4. a decoder 22; a waveform shaping circuit 23 that performs edge emphasis by adding a second-order differential waveform to the output of the decoder 22;
An encoder 24 is provided for modulating the output of the waveform shaping circuit 23 into a color signal.

As shown in FIG. 2, the waveform shaping circuit 23 delays the color difference signal s (B) to be shaped by one hour each using two cascaded delay circuits 25 and 26, and outputs the output of the delay circuit 25. After adding to the original signal in the adder 27, the coefficient unit 28
The subtracter 29 attenuates the output of the delay circuit 25, and the adder 30 attenuates the output of the delay circuit 25.
The configuration is such that it is added to the output of 5. The signal waveforms of each part of the waveform shaping circuit 23 =4= are as shown in FIGS. 3(A) to (F), and the second-order differential waveform obtained from the subtracter 29 is used as an aperture correction waveform for waveform shaping. . That is, unlike the conventional compensation method in the frequency domain, the waveform shaping circuit 23 corrects the signal waveform of the color difference signal in the time domain,
Blunting of the signal edge portion can be eliminated.

In this manner, the magnetic recording/reproducing device 21 performs high frequency conversion on the reproduced color signal reproduced from the magnetic tape 9, and then demodulates the reproduced color signal into a color difference signal in the decoder 22, and the waveform shaping circuit 23 applies the obtained color difference signal. After performing waveform shaping by adding a second-order differential waveform, it is modulated into a color signal by the subsequent encoder 24,
Since the configuration is such that the reproduced color signal is mixed with the demodulated reproduced luminance signal and output, the reproduced color signal is not added to the demodulated luminance signal immediately after high frequency conversion, but is first demodulated into a color difference signal, which is a baseband signal. By performing edge enhancement processing in the time domain, it is possible to perform high-frequency compensation that goes one step further on the signal waveform itself, and it is possible to compensate for degraded waveforms that cause color fringing through waveform shaping, and eliminate color fringing from reproduced images. I can do it. In addition, by combining deterioration countermeasures in the frequency domain such as pre-emphasis during recording and de-emphasis during playback, composite high-frequency compensation is possible.

In the second embodiment, the waveform shaping circuit 23 is configured to emphasize the effect by adding a second-order differential waveform to the color difference signal, but the additional waveform is not limited to the second-order differential waveform. The differential waveform may be other aperture correction waveforms.

[Effects of the Invention] As explained below, the present invention performs high-frequency conversion on the reproduced color signal reproduced from the magnetic tape, demodulates it into a color difference signal, further waveform-shapes the obtained color difference signal, and then converts it into a color difference signal. Since it is configured to modulate the color signal and mix it with the demodulated reproduced luminance signal and output it, it is possible to perform high-frequency compensation of the reproduced color signal through waveform shaping of the color difference signal in the time domain, and it is possible to perform high-frequency compensation of the reproduced color signal through waveform shaping of the color difference signal in the time domain. Differently, color fringing can be eliminated from the reproduced image by a step-by-step shaping process on the signal waveform itself, and by combining high-frequency compensation methods in the frequency domain such as pre-emphasis during recording and de-emphasis during playback. , it has excellent effects such as being able to more effectively improve image quality.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram showing an embodiment of the magnetic recording/reproducing apparatus of the present invention, and FIGS. 2 and 3 are a circuit diagram of the waveform shaping circuit shown in FIG. 1 and signal waveform diagrams of various parts of the circuit, respectively. Fourth
This figure is a circuit configuration diagram showing an example of each part of a conventional magnetic recording/reproducing apparatus, and FIG. 5 is a diagram showing frequency distributions of color signals and luminance signals recorded on a magnetic tape. 210. Magnetic recording/reproducing device, 22. ,,decoder, 23
．． ,, waveform shaping circuit, 24 encoder.

Claims (1)

[Claims] A decoder that is connected to a high frequency conversion circuit that converts a low frequency converted color signal reproduced from a magnetic tape on which a frequency modulated luminance signal and a low frequency converted color signal are frequency-multiplexed recorded, and demodulates the color signal into a color difference signal. , a waveform shaping circuit that shapes the waveform of each of the color difference signals demodulated by this decoder in the time domain, and a waveform shaping circuit that modulates the waveform shaped color difference signal by this waveform shaping circuit into a color signal and mixes it with the demodulated reproduced luminance signal. 1. A magnetic recording and reproducing device comprising an encoder for providing