JPH02140081A - Video signal recording device - Google Patents

Abstract

PURPOSE:To attain the recording onto a recording medium while a character information signal is superimposed without deteriorating the waveform by providing a character information signal addition circuit adding and recording a character information signal to a part of a period of a luminance signal to a transmission line of the luminance signal. CONSTITUTION:An output of a changeover switch 25, that is, a luminance signal Y separated from a composite video signal from an input terminal 21 or a signal Y inputted separately independently from an input terminal 22 is fed to a character signal addition circuit 28 via an AGC circuit 27. The circuit 28 adds a character signal to the video signal part of the luminance signal Y to keep the level of the luminance signal constant, then the character signal with a constant level is always added. Then the luminance signal is inputted to an input terminal of an adder 31 via an emphasis circuit 29 and an FM modulator 30. On the other hand, an output of a changeover switch 26, that is, a chrominance carrier signal C or a separate and independent input signal C is inputted to the other input terminal of the adder 31 via a low frequency conversion circuit 32. The signals Y, C are subjected to frequency division multiplex in the adder 31, the result is fed to a magnetic head 34 and recorded on a tape 35.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a video signal recording device, and particularly to a video tape recorder (V
TR) and other video signal recording devices.

(Prior Art) Recently, teletext broadcasting (texttext) has been put into practical use as a new broadcasting service. Information such as text and images of this teletext is multiplexed and broadcast (transmitted as a digital signal) during the vertical blanking period of the television signal (television radio waves) from the currently broadcasting station.
If the recipient side prepares a receiving device or adapter (teletext decoder) capable of receiving teletext, they can select and enjoy the desired teletext program from among many teletext programs.

In the above-mentioned teletext broadcast, the addition of the character signal to the television signal (video signal) at the broadcasting station is carried out as shown in FIG. After superimposing the teletext signal input from the input terminal 3 on the signal, the signal is transmitted (on air) by the transmitter 4.

Further, in recent years, video tape recorders have made remarkable progress, and home video tape recorders that can transmit even the necessary bandwidth for character signals have been realized. When recording video signals on such a video tape recorder, the date and explanation (text)
A conceivable application would be to record information added to a video signal as a text signal, and then, during playback, the text signal added to the video signal is decoded by a teletext decoder and viewed as a date, explanation (text), etc.

At this time, a block diagram when a character signal is added to a composite video signal as in the case of the above-mentioned broadcasting station is shown in FIG.

In FIG. 6, a composite video signal inputted from an input terminal 5 is added (superimposed) with a character signal in a character signal addition circuit 6, and then is further supplied to a luminance/color (Y/C) separation circuit 7.
Here, it is separated into a luminance signal Y and a carrier color signal C.

The Wirx signal Y separated from the composite video signal is sent to the AGC circuit 8. The carrier color signal C separated from the composite video signal is supplied to one input terminal of the adder 11 via the emphasis circuit 9 and the FM modulator 10, while the carrier color signal C separated from the composite video signal is supplied to the low frequency conversion circuit 12.
The signal is supplied to the other input terminal of the adder 11 via the frequency-modulated luminance signal Y and the carrier color signal C converted to a low frequency band, which is frequency-division multiplexed. Furthermore, adder 11
The output is supplied to the magnetic head 14 via the recording amplifier 13 and recorded on the magnetic tape 15.

Another method of adding character information to a video signal is to use a so-called character generator.
As shown in the figure, there is a method of generating pulses distributed over several lines and superimposing them on the video signal portion. The screen at this time becomes as shown in FIG.

(Problem to be Solved by the Invention) However, when adding a character signal to a composite video signal by the method shown in the block diagram of FIG.
/C If a comb filter is used as a separation circuit, there is no correlation between lines in the character signal portion, so character signals added (superimposed) to adjacent lines are mixed by the comb filter, causing waveform deterioration of the character signal. Problems such as this arise.

Also, as a Y/C separation circuit, LP is used for luminance signals.
If a BPF is used for the F and carrier color signals, a problem arises in that the high-frequency component band of the character signal is limited by the PF, causing waveform deterioration.

Also, as mentioned above, when a character generator generates pulses distributed over several lines and superimposes them on the video signal to add text information to the video signal, - degree, text information is added to the video signal. Once added (superimposed), it is difficult to remove it, and there is a problem in that the character information recorded on the magnetic tape by a video tape recorder cannot be erased or rewritten.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a video signal recording device that solves the problems of the conventional techniques described above.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides video signal recording in which a luminance signal and a carrier color signal are each independently processed and then these signals are recorded on a recording medium. The present invention provides a video signal recording device characterized in that a character information signal adding circuit for adding and recording a character information signal to a part of a period of a luminance signal is provided in a signal transmission path of an IIi signal station. be.

(Embodiment) An embodiment of the video signal recording device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a video signal recording device according to the present invention.

In FIG. 1, a composite video signal is input to an input terminal 21, and separate Y signal (luminance signal superimposed on a synchronization signal) and C signal (carrier color signal) are input to input terminals 22 and 23, respectively. is input.

The composite video signal inputted from the input terminal 21 is supplied to the Y/C separation circuit 24, where it is separated into the lli degree signal Y and the carrier color signal C. The separated luminance signal Y is supplied to one input terminal a of the changeover switch 25, and the separated carrier color signal C is supplied to one input terminal a of the changeover switch 26.

Further, the Y signal inputted from the input terminal 22 is supplied to the other input terminal of the changeover switch 25, and the C signal inputted from the input terminal 23 is supplied to the other input terminal of the changeover switch 26. Ru.

The changeover switches 25 and 26 are switched to the a side when recording the luminance signal Y and carrier color signal C separated from the composite video signal supplied from the Y/C separation circuit 24, and are input from input terminals 22 and 23, respectively. When recording separate and independent Y and C signals, the switch is switched to the b side.

The output of the changeover switch 25 (luminance signal Y separated from the composite video signal or Y signal input separately and independently) is sent to the AGC circuit 2.
7 to a character signal addition circuit 28, where a character signal is added to the video signal portion of the luminance signal Y.

If the character signal is added to the luminance signal after the AGC circuit 27 in this way, the level of the luminance signal is constant, so the character signal of a constant level is always added to the level of the luminance signal. be able to.

The luminance signal to which this character signal has been added is supplied to one input terminal of an adder 31 via an emphasis circuit 29 and an FM modulator 30. On the other hand, the output of the changeover switch 26 (the carrier color signal C separated from the composite video signal or the C signal input separately and independently) is supplied to the other input terminal of the adder 31 via the low frequency conversion circuit 32, and here The frequency-modulated luminance signal Y and the low-frequency carrier color signal C are frequency-division multiplexed.

Further, the output of the adder 31 is supplied to a magnetic head 34 via a recording amplifier 33 and recorded on a magnetic tape 35.

Note that the embodiment shown in FIG. 1 is a luminance signal.

In this example, a low-pass conversion color signal processing method is used as the signal processing of the carrier color signal, but the method is not limited to this example, and other methods may be used as long as the method independently processes the luminance signal and the carrier color signal, for example. The luminance signal is frequency modulated, and the carrier color signal is obtained by compressing the time axis of two color difference signals, then frequency modulating the time division multiplexed signal, and recording each frequency modulated signal on separate tracks of a recording medium such as magnetic tape. It may also be applied to a method in which This also applies to the following examples.

FIG. 2, FIG. 3, and FIG. 4 are diagrams showing other embodiments of the present invention, respectively. In the following figures, the same components as in FIG. 1 mentioned above are given the same numbers.

FIG. 2 is a diagram showing an example of application to a camera-integrated video tape recorder.

In the figure, the camera signal output from the image sensor 36 is R (red) through the camera signal processing circuit 31.

It is extracted as G (green) and B (blue) signals. This R,
The G and B signals are transmitted through the matrix circuit 38 to the luminance signals Y,
Two color difference signals (RY) and (B-Y) are generated, and the luminance signal Y is supplied to a character signal addition circuit 28, where a character signal is added to the video signal portion of the luminance signal Y. and,
The luminance signal to which this character signal has been added is supplied to one input terminal of an adder 31 via an emphasis circuit 29 and an FM modulator 30.

On the other hand, the two color difference signals (R-Y) and (B-Y) are supplied to an orthogonal two-phase modulation circuit 39, where they are subjected to orthogonal two-phase modulation to obtain a carrier color signal C. This carrier color signal C is supplied to the other input terminal of the adder 31 via the low frequency conversion circuit 32, where the frequency modulated B degree signal Y and the carrier color signal C converted to the low frequency are Divided and multiplexed.

Further, as in the embodiment shown in FIG. 1, the output of the adder 31 is supplied to a magnetic head 34 via a recording amplifier 33 and recorded on a magnetic tape 35.

FIG. 3 is a diagram showing a method of adding character signals using an adapter.

In the same figure, 40 is a VTR with YC separate output terminals.
41 is a video equipment such as a VTR which similarly has YC separate input terminals, and 42 is an adapter for adding a character signal to a luminance signal.

The C output terminal of the video equipment 40 is connected to the C input terminal of the adapter 42, which passes through the adapter 42 and is connected to the C input terminal of the video equipment 41 via the C output terminal. Further, the Y output terminal of the video equipment 40 is connected to the Y output terminal of the adapter 42.
It is connected to a character signal addition circuit 43 via an input terminal.

In this character signal addition circuit 43, a character signal creation circuit 45 is operated by operating a character signal input section 44 such as a keyboard.
The character signal created in is added to the video signal portion of the luminance signal Y. The output of the character signal addition circuit 43 is connected to the Y input terminal of the video equipment 41 via the Y output terminal.

FIG. 4 is a modification of FIG. 1, in which a character signal removal circuit 46 is provided between the AGC circuit 27 and the character signal addition circuit 28 in the embodiment shown in FIG. The circuit 46 uses the signal from the character signal addition circuit 28 as a gate signal to remove the character signal in the portion where the character signal is to be added, and then adds a new character signal. Therefore, in this embodiment, the character signal can be rewritten.

In each of the embodiments described above, the text information added to the luminance signal may be a teletext signal used in broadcasting, or may be any other variety of text information signals.

(Effects of the Invention) As described above, according to the video signal recording device of the present invention, Y/
Since the character signal is added (superimposed) to the luminance signal after C separation, even if a comb filter is used as a Y/C separation circuit,
Character signals from adjacent lines do not mix, and this comb-shaped filter allows character information signals to be added (superimposed) and recorded on a recording medium without deteriorating the waveform of the character information signals. Even if the information is separated by the LPF, the character information signal can be recorded without being subjected to band restriction by the LPF.

Furthermore, since the text information signal is not added to the video signal portion (@tatami), it is possible to display or erase text or other information on the monitor, and furthermore, it does not affect the video signal in any way. It has the advantage of being able to convert text information signals without any trouble.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of a video signal recording device according to the present invention, FIGS. 2, 3, and 4 are diagrams showing other embodiments of the present invention, and FIG. 5 is a block diagram showing an embodiment of the video signal recording device of the present invention. Figure 6 is a block diagram showing an example of a conventional video signal recording device, and Figures 7 and 8 are diagrams for explaining the addition of text signals on the station side. It is a figure for explaining a method. 21, 22.23... Input terminal, 24... Y/C separation circuit, 25, 26... Changeover switch, 27... A
GC circuit, 28...Character signal addition circuit, 29...Emphasis circuit, 30...FM modulation circuit, 31...
Adder, 32... Low frequency conversion circuit, 33... Recording amplifier, 34... Magnetic head, 35... Magnetic tape, 3
6...Image sensor, 31...Camera signal processing circuit, 3
8... Matrix circuit, 39... Orthogonal two-phase modulation circuit, 40, 41... Video equipment, 42... Adapter, 4
3...Character signal addition circuit, 44...Character signal input section, 45...Character signal creation circuit, 46...Character signal removal circuit. Figure 3

Claims (1)

[Claims] After independently processing the luminance signal and the carrier color signal,
A video signal recording device for recording these signals on a recording medium is characterized in that a text information signal addition circuit for adding and recording a text information signal to a part of the period of the luminance signal is provided on the transmission path of the luminance signal. video signal recording device.