JPS6154315B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a video signal recording and reproducing device, and an object of the present invention is to provide a device that can achieve high quality recording and reproducing with a simple configuration and with less cost increase.

The luminance signal recording system of the color signal reduction conversion low carrier frequency modulation method, which is currently commonly used as a recording method for color video signals, passes the luminance signal through a low-pass filter to separate it from the composite color video signal. FM low pass filter output
The signal is modulated and then recorded on a recording medium through a high-pass filter or a trap that limits the band corresponding to the low-pass converted color band. In other words, since the band originally included in the luminance signal is recorded while being limited, the reproduced signal has poor resolution. This poor resolution is not so much of a concern for signals that do not require detailed discrimination in complex screens such as landscape paintings, but for signals that do not require detailed discrimination, such as white text with blue backs, and a large number of characters arranged across the entire screen. Signs like this make it difficult to read the characters. Furthermore, since the entire back of the character screen is a single color, the visual detection limit for color noise is several dB higher than on a normal screen, so it is necessary to improve the color S/N than before. One of the ways to improve the above problems of resolution deterioration and color S/N deterioration is that the relative speed between the recording medium and the recording head used in broadcasting stations is extremely fast, and the recording head It is conceivable to use the direct FM method found in 2-inch VTRs, which have a wide track width, but the overall configuration of the device is complex and it is necessary to improve the general performance compared to the color signal low frequency conversion method. , which has the disadvantage of being very expensive.

Therefore, the present invention has been made by focusing on the above-mentioned problems.In order to achieve the above-mentioned object, the present invention first describes a video signal in which a plurality of color signals are mixed, such as a landscape painting, in the conventional example. Recording and playback are performed using a color signal low-pass conversion method, and as mentioned above, character screens with blue backs on white characters are captured in advance with a black and white camera and recorded in black and white mode, which is not subject to the limitations of the luminance signal band. The video signal is recorded on a recording medium and is configured to electrically add a blue back color to the reproduced video signal during reproduction.

An embodiment of the present invention will be described below based on the drawings.

FIG. 1 shows a block diagram of a large-capacity still picture memory reproducing apparatus. Reference numeral 1 denotes a still picture memory section, which consists of a recording medium, a magnetic head, and a motor. 2 is a head amplifier, 3 is a high-pass filter, 4 is an FM demodulator, 5 is a color low-pass filter, 6 is a monochrome low-pass filter, 7 is a color signal mixing video amplifier, 8 is a low-pass filter, 9 is a color signal high-frequency conversion circuit , 10 is a color burst signal discriminator. Each switch SW01 to SW04 is turned ON when the color burst signal discriminator 10 determines that there is no color burst, and the switching state in Fig. 1 is OFF.
Indicates the state in which color signals are being reproduced. In other words, if a color signal is recorded on the recording medium, the output of the color signal mixed video intensifier 7 is output as is to the output terminal ( ). This is a common type of reproduction system using the so-called low frequency conversion method. Also 11
is a synchronization signal generator which generates a burst flag signal a, a blanking signal b and a synchronization signal c synchronized with the video signal output from the color signal mixing video amplifier 7.
occurs. 12 is a subcarrier oscillator,
Generates 3.58MHz continuous wave d. 13 is a phase shifter;
A 3.58MHz continuous wave e is generated by shifting the phase of the continuous wave d. A waveform shaper 14 extracts a character signal, a signal indicating a figure, etc. from the video signal output from the color signal mixing video amplifier 7, and generates a waveform-shaped signal f. Reference numeral 15 denotes a color signal synthesizer which adds a color burst signal and a color signal to a reproduced video signal from the signals a to c, continuous waves d and e, and signal f, and outputs the resultant as an NTSC color signal g.

FIG. 2 shows the configuration of the color signal synthesizer 15,
A burst signal is generated from the signals a and d, a back color luminance signal is generated from the signals b and f, a back color signal is generated from the signals b, f, and e, and the respective outputs h, i, j and the signal f are combined by a mixer 16 to produce a color signal. In addition to obtaining a video signal, the mixer 17 generates a synchronization signal c.
is added to make it an NTSC color signal.

With the above configuration, if the output of the memory section 1 is black and white, and the signal is a white character W with a background of gray level G as shown in FIG. As shown in FIG. 3b, a signal with a white character W with a colored background is obtained.

Note that the hue of the back color c can be freely selected by changing the amount of phase shift of the phase shifter 13. Further, by partially changing the configuration of the color signal synthesizer 15, it is possible to color the character portion as well. In addition, when recording to the still image memory section 1, as shown in Fig. 4, by selecting and recording the brightness level of areas other than character D from three levels ABC, the back color of the playback signal is automatically changed. It is also possible. Note that during normal color signal reproduction, it operates as an original color signal regenerator, and there is no deterioration in characteristics.

As described above, according to the present invention, a discriminator is provided for determining the presence or absence of a color burst signal in a reproduced video signal, and when the discriminator detects a color burst signal, the reproduced video signal is output to an output terminal. a synchronizing signal generator that generates a color burst flag signal, a blanking signal, etc. that is synchronized with the reproduced video signal, an oscillator that outputs a subcarrier, and a phase shift of the subcarrier output from the oscillator for reproduction. A phase shifter that determines the hue of the background of an image, a waveform shaper that shapes the waveform of the reproduced video signal and extracts character and graphic signals, and a synchronization signal generator output signal, an oscillator output signal, and a phase shifter output signal. a color signal synthesizer that adds a color burst signal and a color signal of the background hue determined by the phase shifter to the character/figure signal generated at the output of the waveform shaper to output an NTSC color signal; When the discriminator determines that there is no color burst signal, the output signal of the color signal synthesizer is output to the output terminal instead of the reproduced video signal, and the color signal is added to the reproduction system of the still image memory. , signals such as character images with background colors on white characters can be recorded in black and white mode, and there is no deterioration in resolution due to band limitations as seen in low frequency conversion methods, and color signals can be recorded. Since there is no need to pass the image through a reproduction system, a clear image with good color S/N can be obtained.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a configuration diagram of a video signal recording and reproducing device, FIG. 2 is a configuration diagram of a color signal synthesizer of the same device, FIG. 3 is an explanatory diagram of the same device, and FIG. The figure is a waveform diagram showing another embodiment of the same device. 10... Color burst signal discriminator, 11...
Synchronous signal generator, 12... subcarrier oscillator,
13... Phase shifter, 15... Color signal synthesizer.

Claims (1)

[Claims] 1. A discriminator for discriminating the presence or absence of a color burst signal in a reproduced video signal is provided, and when the discriminator detects a color burst signal, the reproduced video signal is output to an output terminal, and the reproduced video signal is A synchronization signal generator that generates a synchronized color burst flag signal and a blanking signal, an oscillator that outputs a subcarrier, and a phase shifter that shifts the phase of the subcarrier output from the oscillator to determine the background hue of a reproduced image. a waveform shaper that shapes the waveform of the reproduced video signal to extract character and graphic signals, and a character generated at the output of the waveform shaper by the synchronization signal generator output signal, the oscillator output signal, and the phase shifter output signal. A color signal synthesizer is provided that outputs an NTSC color signal by adding a color burst signal and a color signal of the background hue determined by the phase shifter to the graphic signal, and the discriminator determines that there is no color burst signal. A video signal recording and reproducing device that outputs an output signal of the color signal synthesizer to an output terminal instead of the reproduced video signal when the video signal is reproduced.