JPH025069B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a television image superimposition device.

Conventionally, as shown in FIG. 1, for example, a receiver is connected between a receiver 2 of a color television receiver (hereinafter referred to as a color TV receiver) and a drive circuit 3 of a CRT (cathode ray tube) 4, A television image superimposing device 1 is known that outputs a video signal representing an image obtained by superimposing a desired image on a TV image.
This type of superimposition device basically uses a digital color signal that is a binary version of an analog color signal representing the text character to be superimposed on the TV.
Among the color signals from the chroma IC in the receiving device 2 of the receiver, the signal corresponding to the part to be superimposed is blocked, and the binarized color signal of the text character signal is inserted into the blocked part. A device that outputs a video signal consisting of
In this way, since the color signal representing the superimposed image output from the superimposition device 1 is a binary "1" or "0" signal, the image superimposed on the TV image has a certain There was a problem in that images could only be displayed in hue or saturation, but not in various so-called intermediate colors.

This invention was made in order to eliminate the above-mentioned problems, and is intended to eliminate the problems described above.
2 representing the superimposition image mixed with the TV image signal
The level of the digitized signal “1” is changed according to the analog signal representing the image for superimposition,
An object of the present invention is to provide a television image superimposition device that can display images superimposed on a TV image with various hues and saturations.

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 2 shows a superimposition device for superimposing, for example, text characters received by a teletext receiver onto a color TV image displayed on a color TV receiver.

In Figure 2, 10-
R, 10-G, 10-B and 10-Y are all signal mixing circuits for generating a TV video signal for displaying a color TV image with color teletext characters superimposed thereon.

The signal mixing circuit 10-R basically includes an amplifier circuit 13 which is formed by connecting two transistors, a PNP transistor 11 and an NPN transistor 12, in a complementary manner so that the amplification factor is 1, and the amplifier circuit 1.
An inverter 14 connected to the base of the NPN transistor 12 in the output stage of the amplifier circuit 13 and a collector of the NPN transistor 12 in the output stage of the amplifier circuit 13 are connected via a filter circuit consisting of a resistor r and a capacitor C. It is composed of Nand Gate 15-R. In addition, the resistance r is as described below.
When the output of the NAND gate is "0", the collector of the cut-off transistor 12 is set to be at the pedestal level. Setting the value of the resistor r to a small value is more effective for all frequency components of the superimposed character/figure signal. cannot be made smaller. Therefore, if the superimposed text/figure signal is a high frequency component, there is a risk that the TV image cannot be blocked sufficiently. There is.

Other signal mixing circuits 10-G and 10-B are
It has the same configuration as the signal mixing circuit 10-R described above, and the same reference numerals are given to the equivalent components, and the explanation thereof will be omitted.
Another signal mixing circuit 10-Y is a two-input NAND gate 1 in the signal mixing circuit 10-R.
5-R is replaced with an inverter 15-Y, and the other components are the same as those of the signal mixing circuit 10-R. Note that the amplifier circuit 13 in each of the signal mixing circuits described above may use an NPN transistor in the input stage and a PNP transistor in the output stage.

Each signal mixing circuit 10-R, 10-G, 10-
A chroma IC (not shown) of the color TV receiver is connected to the base of the transistor 11 in the input stage of the amplifier circuit 13 of B and 10-Y.
Demodulated color difference signals (RY), (G
-Y), (BY), and a luminance signal Y are input.

The above signal mixing circuit 10-R, 10-G, 10-
Each inverter 14 in B and 10-Y is
Commonly, for example, TTL (transistor-transistor logic) level converter circuit 18-Ys
is connected to. And the signal mixing circuit 10-
One input terminal of the NAND gates 15-R, 15-G and 15-B in R, 10-G and 10-B is connected to, for example, TTL level inverting converter circuits 18-R, 18-G and 18-, respectively. The other input terminal is commonly connected to the converter circuit 18-Ys. Further, the inverter 15-Y in the signal mixing circuit 10-Y is the converter circuit 1
8-Connected to Ys.

These converter circuits 18-R, 18-G and 18-B respectively receive three primary color analog color signals R representing text characters, figures, etc. to be superimposed on a color TV image from a teletext receiver (not shown). ′ (red), G′ (green) and B′ (blue). Further, the converter circuit 18-Y synthesizes the analog color signals R', G', B' representing the text characters described above and the blanking signal BLK from the blanking signal generation circuit (not shown) in the teletext receiver. It is connected to receive the analog signal Ys=BLK+R'+G'+B'.

The above converter circuit 18-R, 18-G, 18
-B, 18-Ys compares the input analog signal with a predetermined threshold signal using a known method, and when the input analog signal is larger than the threshold signal, it outputs a “1” signal, and conversely, the input analog signal outputs a “1” signal. When the signal is below the threshold value, a "0" signal is output. In this way, each converter circuit 18-R, 18-
G, 18-B, and 18-Ys output digital signals obtained by binarizing the analog signals R', G', B', and Ys, respectively.

20-R, 20-G, 20-B, and 20-
Both Y are the signal mixing circuits 10-R and 1 described above.
Of the video signals output from 0-G, 10-B and 10-Y, the digital signal component representing the text character to be superimposed is converted into an analog signal corresponding to the level of the output signal from the teletext receiving device. This is a signal conversion circuit that converts signals.

The collector of the transistor 21 in the signal conversion circuit 20-R is connected to the signal mixing circuit 10-R.
The base is connected to the connection point t between two voltage dividing resistors R ₁ and R ₂ connected in series to the constant voltage power supply +B, and
The emitter is grounded through resistor _R3 . The other electrode of the capacitor _C2 , one electrode of which is connected to the emitter of the transistor 21, is
Via resistor R ₄ to the above teletext receiver,
Analog color signals representing the text characters mentioned above
It is connected to receive R′. In addition, _C1 is
filter capacitor for removing noise signals,
_R5 is a resistor that shunts the analog signal input to the signal conversion circuit 20-R.

Other signal conversion circuits 20-G, 20-B, 20-
Y has a configuration similar to that of the above-described signal conversion circuit 20-R, and equivalent components are given the same reference numerals and explanations thereof will be omitted.

Next, as in FIG.
The operation when connected and used with a drive circuit will be explained.

From the Chroma IC in the receiving device of the TV receiver,
Color difference signals representing TV images (RY), (G-Y),
(B-Y) and luminance signal Y are signal mixing circuits 10-R, 10-G, 10-B and 1, respectively.
It is applied to the base of the transistor 11 in the input stage of each amplifier circuit 13 of 0-Y. Also, an analog color signal representing a portion of a text character representing a character/figure having a predetermined pulse width corresponding to each pixel of a TV image to be superimposed from a teletext receiver.
R', G', and B' are respectively the converter circuit 18
-R, 18-G, 18-B, and a signal Ys that is a composite of these analog color signals R', G', B' and blanking signal BLK = BLK + R' +
G'+B' is applied to converter circuit 18-Ys.
The pulse width of each analog color signal R', G', B' is denoted by T.

Suppose now that the text character is red, so the signal R' has a certain analog voltage, and the signal G' representing the green component and the signal B' representing the blue component are both zero. It is also assumed that the horizontal blanking circuit of the teletext receiver does not output the blanking signal BLK, and therefore the composite signal is Ys=0+R'+0+0=R'.

The analog color signal R' input to the inverting converter circuit 18-R is larger than a predetermined threshold value, so "0" is output from the converter circuit 18-R. Further, the analog color signals G' and B' input to the other inverting converter circuits 18-G and 18-B are both zero, and both signals are smaller than a predetermined threshold.
Therefore, both converter circuits 18-G, 18-
"1" and "1" are output from B, respectively.
Further, the analog composite signal Ys=R' input to the converter circuit 18-Ys is larger than a predetermined threshold value, and therefore, this converter circuit 18-Ys is larger than a predetermined threshold value.
“1” is output from Ys.

The output “1” of the above converter circuit 18-Ys is
Each signal mixing circuit 10-R, 10-G,
It is inverted to "0" by the inverters 14 of 10-B and 10-Y, and applied to the base of the transistor 12 of the amplifier circuit 13 of each signal mixing circuit.
Therefore, the base potential of the transistors 12 at the output stage of each amplifier circuit 13 decreases and is cut off.

Further, the output "1" of the converter circuit 18-Ys is the NAND gate 15- of each signal mixing circuit.
R, 15-G, and 15-B, and the converter circuits 18-R and 15-B are applied to the other input terminal of each NAND gate, respectively.
“0”, “1”, and “1” are applied from 18-G and 18-B. Therefore, these Nand Gate 15-
R, 15-G, and 15-B apply "1", "0", and "0" to the output terminals 16-R, 16-G, and 16-B of each signal mixing circuit, respectively. Furthermore, the output "1" of the converter circuit 18-Ys is transmitted to the inverter 15 of another signal mixing circuit 10-Y.
- Inverted to “0” by Y, the signal “0”
is applied to the output terminal 16-Y.

Here, the inverter circuit 14 and the NAND gate 1
5-R, 15-G, 15-B, and 15-Y are all open collectors.

Therefore, in this case, since the analog color signals G' and B' are 0, the output of the transistor 12, 16-
G, 16-B is the period of color signal R' (G-Y),
Cut off each input of (BY). At this time, the resistance r of the NAND gate is set to the pedestal level. (See Figure 4 a, b) Also, since R' is 1 in 16-R, the resistance r
And the level did not go down in Nand Gate 15-R and the 4th
It will look like figure c. In this way, the color difference signal (R-
Y), (G--Y), (B--Y) and the luminance signal Y are text character signals and are killed either at the pedestal level position or at the cut-off level position.

On the other hand, the analog color signals R', G' = 0, B' = 0, Ys = R' representing the text characters are 3, respectively.
Each signal mixing circuit 20-R, 20 is converted into a negative voltage by 0-R, 30-G, 30-B, 30-Y.
- Resistance R ₄ , R ₅ at 20-B, 20-Y
is applied to the other electrode of capacitor _C2 through. Therefore, the potential at the emitter of the transistor 21 of each signal mixing circuit is equal to the voltage R',0,0,0, applied to the other electrode of each capacitor _C2, respectively.
It decreases by an amount corresponding to Ys=R′. In addition, the base of the transistor 21 of each signal conversion circuit is connected to a voltage dividing ratio of resistors R ₁ and R ₂ from a constant voltage power supply +B.
A constant positive voltage proportional to R ₂ /R ₁ +R ₂ is applied. Therefore, in the collector voltage of the transistor 21 of the signal conversion circuit 20-R, a potential difference occurs between the base and the emitter, a current flows between the collector and the emitter, and a voltage drop occurs due to the collector resistance. That is, the signal mixing circuit 10 indicates that the signal is mixed or inserted into the color difference signal (RY) representing the TV image.
The digital video signal output from R is converted into an analog video signal corresponding to the color signal R' of the text character. Note that the outputs from the other signal mixing circuits 10-G, 10-B, and 10-Y during the period T are all at the pedestal level, and the outputs from the signal converting circuits 20-G, 20-B, and 20-Y
Each transistor 21 in is cut off and is not operating.

As a result, during the period T, from the output terminal 25-R of the superimposing device, the signal conversion circuit 20
- the collector voltage of transistor 21 at R,
That is, a color difference signal (RY) corresponding to the color signal R' representing the text characters superimposed on the TV image is output. Other output terminals 25-G, 25-B,
Both outputs of 25-Y are at the pedestal level during the period R'.

Therefore, the output terminal 25-R of the superimposing device is connected to the R cathode terminal of the CRT in the TV receiver.
A voltage is applied according to the video signal from the
No voltage is applied to the other G and B cathode terminals of the CRT. As a result, the CRT screen will display the relevant TV.
The text characters received by the teletext receiver are displayed superimposed on the TV image in red with a saturation corresponding to the analog color signal R', without color mixing with the image color.

Now assume that the text characters above are white.
That is, the analog color signals R', G', and B' have voltages at the same level, and these analog color signals are connected to the converter circuits 18-1, respectively.
Suppose that R, 18-G, and 18-B have an analog voltage greater than the threshold.

Three inverting converter circuits 18-R, 18
-G, 18-B respectively “0”, “0”,
“0” is output. In addition, the converter circuit 18
-Ys outputs "1" as described above. Therefore, due to the output "1" of the converter circuit 18-Ys, the corresponding
Signals representing TV images (RY), (G-Y), (B
-Y), Y are both killed, and
The output terminals 16-R, 16-G, 16-B of the signal mixing circuits 10-R, 10-G, 10-B receive "1", "1" from the NAND gates 15-R, 15-G, 15-B. ”, “1” are applied. Furthermore, color signals R', G', and B' are applied to each capacitor _C2 of the signal conversion circuits 20-R, 20-G, and 20-B.
Therefore, these signal conversion circuits 20-R, 2
For 0-G, 20-B, the signal mixing circuits 10-R, 10-G, 10-B are connected in the same manner as described above.
The outputs "1", "1", and "1" from the converter change according to the analog color signals R', G', and B', respectively. These video signals are then applied to the R, G, and B cathode terminals of the CRT. Therefore, white text characters in which color components R', G', and B' are mixed are displayed on the CRT screen, superimposed on the TV image. Further, when the text characters are mixed colors, that is, when the analog color signals R', G', and B' do not have voltages at the same level, the signal mixing circuit 10- R, 10-
The outputs of G and 10-B are changed by signal conversion circuits 20-R, 20-G and 20-B, respectively, into signals corresponding to analog color signals representing text characters. Therefore, the CRT screen displays the color component.
Text characters of a mixed color in which R', G', and B' are mixed are displayed superimposed on a TV image without color mixing with the TV image.

Note that an analog color signal R′ representing a text character is sent from the teletext receiver to the superimposing device.
When inputting G' and B' and simultaneously inputting a blanking signal BLK having a predetermined voltage and pulse width, the output of the converter circuit 18-Ys becomes Ys = "1" + R' + G' + B', and this signal Ys＝
By “1”, the signal mixing circuits 10-R, 10-G,
Signals representing TV images input to 10-B, 10-Y (RY), (G-Y), (B-Y) and Y
are both killed. In addition, the NAND gates 15-R, 15-G, 15-B and the inverter 15-B in the area where the text character part of the pixel is not occupied, that is, the period of R'=0, G'=0, B'=0. The output of Y is “0”, “0”,
Therefore, during the period, the output terminals 25-R, 25-G, 2 of the superimposing device
The video signals of 5-B and 25-Y are both at the pedestal level. Therefore, it corresponds to the pixel in question.
The CRT screen displays text characters against a black background.

On the other hand, TV image signals (R-Y), (G-Y),
(B-Y), if you stop inputting Y, output terminal 25
-R, 25-G, 25-B, and 25-Y, only signals corresponding to the text character signals R', G', and B' are sent as described above. Therefore, the TV in question
Only text characters are displayed on the CRT screen of the receiver.

Also, the text character signals R', G', B' and the composite signal from the teletext receiver to the superimposing device are
If the input of Ys is stopped, the signal mixing circuit 10-R,
The amplification factor of each amplifier 13 of 10-G, 10-B, and 10-Y is 1. Therefore, the TV image signals (R-Y), (G
-Y), (B-Y), Y are output terminals 16-R, 16-G, respectively, without being amplified.
It is output to 16-B and 16-Y. In this case, the signal conversion circuits 20-R, 20-G, 20-B, 20
The voltage applied to the other electrode of each capacitor C ₂ at -Y leads transistor 21 into cut-off. Therefore, the TV from each signal conversion circuit mentioned above
Image signals (R-Y) (G-Y), (B-Y), Y are
Both images are amplified at a constant amplification factor, and only the TV image is displayed on the CRT screen of the TV receiver.

As explained above, according to the present invention, since the television signal is blocked in the portion where the superimposition image and the television image overlap, color mixing between the television image and the television image does not occur. Moreover, since the text characters are made to change according to the analog value of the image signal for superimposition, the image for superimposition can be displayed on the screen of the television receiver in a color tone corresponding to the analog signal representing the image for superimposition. .

[Brief explanation of drawings]

FIG. 1 is a block diagram for explaining the basic configuration of a conventional video signal superimposing device, FIG. 2 is a circuit diagram of a superimposing device according to an embodiment of the present invention, and FIGS. 3 and 4 are , is a diagram showing voltage waveforms of main components in the signal mixing circuit of the superimposing device of FIG. 2; 10-R, 10-G, 10-B, 10-Y...signal mixing circuit, 13...amplification circuit with amplification factor 1, 14...
Inverter, 15-R, 15-G, 15-B...NAND gate, 15-Y...Inverter, 16-R,
16-G, 16-B, 16-Y...Output terminal of signal mixing circuit, 18-R, 18-G, 18-B, 18
-Ys...Converter circuit for binarization, 20-R,
20-G, 20-B, 20-Y...signal conversion circuit,
R-Y, G-Y, B-Y... Television color difference signal, Y... Luminance signal, R', G', B'... Analog color signal of text characters for superimposition, Ys... Composite analog signal, BLK... Black ranking signal.

Claims (1)

[Claims] 1 Connected between the television image signal generation device of the television receiver and the video device, the television image signal and the superimposition image signal to be superimposed on the television image are compared with a predetermined threshold signal to generate a binary signal. A cutoff circuit receives the converted signal and cuts off the signal corresponding to the portion of the television image signal on which the superimposition image is to be superimposed on the television image; Among the output signals of the signal mixing circuit, the level of the binarized signal "1" of the inserted image signal for superimposition is converted into the image signal for superimposition. A television image superimposition device comprising: a signal conversion circuit that changes the signal according to an analog value of the television image.