JPS58159082A - Superposing device of character and pattern signals - Google Patents

Abstract

PURPOSE:To attach easily a superposing device to a TV receiver without changing the circuit constitution of the TV receiver, by projecting independent video information for superposition together with TV picture information onto a video screen of the TV receiver by the output of an amplifying circuit of the superposing device. CONSTITUTION:A superposing device 10 is connected to a picture receiving device 11 of the TV receiver, and the TV picture signal from the device 11 is applied to the superposing device 10, and the color signal of text characters is supplied to the superposing device 10, and the output of the superposing device 10 is applied to a color CRT13 through a driving device 12 for the CRT. A basic circuit 15 of the superposing device 10 is provided with an amplifying circuit 22 where the amplification factor due to a PNP transistor TR16 and an NPN TR17 is 1, and color signals R, G, and B of the TV picture are inputted to the base of the TR16. A signal which breaks the part of the video information signal for superposition is applied to the base of the TR17 through the first logical gate IC23. Video information for superposition is applied to the second logical IC gate 25 provided to the output side of the circuit 22, and thus, video information for superposition is displayed on the CRT13 without changing the circuit constitution of the TV receiver.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a character/graphic signal superimposition device, more specifically, to superimposes predetermined character/graphic information on image information received by a television receiver or to separate the character/graphic information independently. This invention relates to a superimposing device for displaying images on a computer.

As shown in FIG. 1 or 2, this type of superimposing device has conventionally been used, for example, on the input side of a drive circuit 2 for driving a CRTl (cathode ray tube) of a color television receiver; On the output side of the color television receiver, a color signal representing image information from the chroma IC 3 (integrated color signal demodulation circuit) and a text message receiver or teletext receiver (not shown) are output. While a mixing circuit 4 or 4 is provided for mixing color signals representing graphic (hereinafter referred to as text character) information, the above-mentioned A switching circuit 5 or 5 is provided which operates on the basis of a text character signal to be superimposed, and a switching circuit 5 or 5 is provided which operates in a switching manner based on the text character signal to be superimposed, so that the text character part corresponding to the text character signal is superimposed on the color image received by the television receiver so as not to mix colors. Period, Chroma I
A structure in which the color signal output from C3 is blocked is known.

However, in the conventional superimposing device described above, the chroma IC 3 and the drive circuit 2 mounted on the main circuit board (not shown) in the television receiver have the switching circuit 5 and the mixing circuit 4, or the switching circuit 5 and the mixing circuit The connection mechanism for connecting the circuit 4 is very complex and requires a large number of and quite long lead wires.
There is a drawback that the color signals of the image information to be displayed on the CRTl are adversely affected and the quality of the image displayed on the CRTl is degraded.

Furthermore, as mentioned above, since the switching circuit and the mixing circuit are separated, the timing of applying the text character signal to be superimposed to the mixing circuit and the switching circuit controlled based on the text character signal can be adjusted. There is a lag between the creation timing, and because of this, C
Text characters displayed on RTl have a black level portion, so-called a black border, which makes them very difficult to distinguish, especially when the displayed text characters are small.

The present invention was made to eliminate the above-mentioned drawbacks, and the demodulated television image is processed by baking a transistor in the input stage of an amplifier circuit configured to have an amplification factor of 1 using at least two transistors. A cutoff signal is generated based on a superimposition video information signal to be superimposed on the television image signal while inputting the signal, and is for blocking a portion of the television image signal that corresponds to the superimposition video information signal. is applied to base 7 of the transistor in the output stage of the amplifier circuit, and a signal representing superimposition video information is applied to the output terminal of the transistor in the output stage to display the video screen of the television receiver. Characters that can display high-quality superimposition video information together with a television image or alone, and that can be easily connected to an existing television receiver without changing the circuit configuration of the television receiver. - The purpose is to provide a graphic signal superimposition device.

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

As shown in FIG. 3, the superimposition device 10 according to the present invention includes:
For example, a chroma IC (not shown) in a receiving device 11 provided in a color television receiver (hereinafter referred to as a television receiver) for receiving commercial television broadcast signals, and a CRT l of the television receiver. It is designed to be connected to the drive device 12 that drives the drive unit B using a pufgooin method.

The superimposition bag @10 contains three color signals (hereinafter referred to as these) representing demodulated color image information of a television broadcast signal received by the television receiver from the chroma IC in the reception device 11. The signals are R (red) signal, G
(green) signal and B (blue) signal) are input, and a horizontal blanking signal (hereinafter referred to as B
LK signal) and, for example, a teletext receiver (denoted as LK signal).
signals representing information such as characters and figures received by the teletext receiver (known ones and not shown);
Three color signals (hereinafter referred to as text character signals) (hereinafter, these color signals are referred to as R' multiplied signal, G' multiplied signal, B/double signal) are input.

The above-mentioned superimposing device 10 receives the above-mentioned R signal and G signal.

Based on the B signal, (R'+G'10B') signal, and the R' multiplied signal G signal and B signal, by a method described in detail later,
A drive signal is generated to control the operation of the drive circuit 12 so that a color image with text superimposed on a television image or a color image of text characters alone is displayed on the screen of the CRT13.

FIG. 4 shows the basic components of the superimposing device 10.

In FIG. 4, the basic circuit 15 for superimposition shown surrounded by a dashed line consists of two pr:rp transistors 16 and an N
PN) run shifter 17, resistance 18.19°20.21
an amplifier circuit 22 connected complementary to each other so that the amplification factor is 1, and a first logic game 1c2 connected to an NPN run shifter 170 at the output stage of the amplifier circuit 22.
3 and a second logic gate rc25 connected to the output terminal 24 of the amplifier circuit 22. Note that this amplifier circuit 22 may be constructed using an NPN) run shifter in the input stage and a PNP) run shifter in the output stage.

The first and second logic ICs 23 and 25 are both formed by integrating open collector transistors, for example. 1st logic) IC2
3 is applied with the C B L K 1 R' 0 G' + B') signal consisting of the above-mentioned text character signal to be superimposed and a blanking signal, and the second logic gate IC2
5, the above-mentioned (BLK+R'10G'+B') signal and a control signal generating circuit 31 (to be described later) in the superimposing device, and a k' signal.

In the superimposing device according to the invention for the G' signal, the R signal obtained by inverting the B signal, and the d'' signal, the chroma IC in the receiving device 11 superimposes the color signals of the three primary colors, that is, the k signal, the G signal,
In the case of a demodulation circuit of a type that outputs a B signal, three basic circuits 15 are provided corresponding to each color signal. Further, the chroma IC has a color difference signal, that is, (R-Y
) signal, (G-Y) signal, and (B-Y) signal, four basic circuits 15 are provided corresponding to each color difference signal and luminance signal (Y signal). provided.

Next, a specific example of a superimposing device in the case where the chroma IC is a color signal demodulation circuit of a type that outputs three primary color signals will be described with reference to FIGS. 5 and 6.

In FIG. 5, 30-R, 30-G, and 30-B are all amplifier circuits equivalent to the amplifier circuit 22 in the basic circuit 15 described above. Each amplifier circuit 30-R, 30-G,
30-B) At the base of the run shifter, the chroma I in the television receiver is
C (not shown) 1, etc., three primary color signals and G signals demodulated from the television image signal received by the television receiver.

A B signal is applied.

Reference numeral 31 denotes a control signal generation circuit for generating a control signal for superimposing a text signal on the television painter signal received by the television receiver.

This control signal generation circuit 31 is configured to receive, for example, an R' signal, a G' signal, and a U/double signal of three primary colors representing a color text character to be superimposed from a teletext receiver (not shown). Connected,〃・
A blanking signal generating circuit (not shown) provided in the teletext receiver is connected to the blanking signal generating circuit so as to receive a blanking signal (hereinafter referred to as a BLK signal). The control signal generation circuit 31 includes, for example, inverters a2-4, 32-G and 32-B using open collector transistors.
via the above-mentioned amplifier circuits 30-R, 30, respectively.
-G, 30-B output stage NPN) run shifter is connected to apply the CB L K+R'+G'+B') signal, and each amplifier circuit 30-R, 30-
G, the collector of the output stage transferer in 3O-BK, that is, the output terminal 33-R, 33 in the superimposing device
-Nando game connected to G and 33-B) 34-
In common to one input terminal of R, 34-G, 34-B,
The control signal generating circuit 31 is connected to apply the above-mentioned (BLK+"10G'+B') signal. Furthermore, the control signal generating circuit 31 is connected to each of the above-mentioned NAND games) 34-R, 34-
The other input terminals of G and 34-B receive the k' signal, the G' signal, and the ni' signal, which are obtained by inverting the polarity of the y' signal.

It is connected to apply the d'' signal and the i'' signal.

The inverters 32-R, 32-G, and 32-B are circuits corresponding to the first logic IC 23 in the basic circuit 15, and the inverters 34-R, 34-
G and 34-B are circuits corresponding to the second logic game 1c25 described above.

Furthermore, the output terminals 33-R, 33-G, and 33-B are connected to the three R, G, and B cathode terminals of the CRT 13 (see Figure 3) in the television receiver, respectively.
circuit (see Figure 3). This drive!4!1 circuit, like the conventional drive circuit shown in Figures 1 and 2, connects the R, G, and B cathodes of CRT 3. It is constructed using three power transistors for driving.

In the superimposing device having the above configuration, a color image is basically projected on the CRT 13 of the television receiver in the projection modes (1) to (3).

(1) Television signal received by the television receiver (
Outputs only D color images; Picture mode (hereinafter referred to as PIC mode).

(2) For example, a color image of text characters from a teletext receiver is superimposed and displayed on the color image of the television signal; mixed mode (hereinafter referred to as MIX
mode).

(3) Display only the color image of the above text characters;
Text mode (hereinafter referred to as K, TEXT mode) In the circuit shown in Figure 5, the demodulated output from the chroma IC in the television receiver, that is, the R, and B signals, are
Blocked or killed based on the following conditions:

(g) T F, X In T mode, television signal e
Blocks the entire image based on K; BLK=1 (a) Blocks the part of the television image that corresponds to the text character to be superimposed; R'10G'+B'=1 Satisfies 1 and (a) above. It is said to be used to encourage people.

Further, in order to drive the drive circuit 12 according to the color output of the chroma IC 7), the color output is applied to the drive circuit 12, that is, passed through the superimposing device, based on the following conditions. Note that the color output is shown only for the red component, and for the other green and blue components! ,, are similar, and will be omitted.

All passes; BLK-R-1 2) In MIX mode, pass through the red part of the text character,
BLK-R=1 3) In PIC mode; BLK-R-G-B=14)
In MIX mode, passing through a portion that does not correspond to a text character i BLK-R-G-B=1 On the other hand, the color output from the chroma IC is completely cut off or killed. Note that the color output is shown only for the red component, and the same applies to the other green and blue components, and these will be omitted.

5) In text mode, block or kill the part corresponding to text character G' or B'; BLK-G, R+B
LK-B, R-1 5) In MIX mode, block or kill the part corresponding to the text character G or B; BLK, G, R-1-BLK-B-R-17) TF, X
In T mode, block or kill the part that does not correspond to the text character signal BLK-R, G-B = 1 Conditions 1) to 7) above are shown in the vp, tTcH (/H) diagram as shown in Figure 6. become that way.

The above-mentioned superimposition device shown in FIG.
This is a circuit that satisfies the conditions of the CH diagram.

Next, FIG. 5 shows the operation sound of the superimposing device having the above configuration.

This will be explained with reference to Figures 7), (b), (C), and Figure 8.

Each red component, green q component, and blue (Bl component) of the demodulated color output from the chroma IC in the television receiver are output to amplifier circuits 30-R and 30-G, respectively.

30-B input stage PNP ) transistor (fifth
In the figure, 85 red components and 6 green components are applied to the text character portion to be superimposed on the demodulated color output television image from the teletext receiver (not shown). , and the blue component are applied to the control signal generation circuit 31.

■, In the case of MIX mode, the text character part is red, i.e., i='″1'
, Q'='''Q', B'='''0', and this period is defined as T1. In addition, a blanking signal (
It is assumed that a signal (hereinafter referred to as a BLK signal)-'''0' is applied to the control signal generation circuit 31.

During period T1, the control signal generation circuit 31 outputs CB L
K 1R'1G'+B') ="o'+ 1j-+-
7o'iO'='l'F to each inverter 32-R, 3
2-G and 32-B, and the signal '1' is applied to each inverter 32-R, 32-G, 32-B! v'O'
This signal '0' is inverted to PN of hexagonal stages in each amplifier circuit 30-R, 30-G, 3O-BIC.
It is applied to the pace of the P transistor (denoted as Tr-1 in FIG. 5). Further, the control signal generation circuit 31 includes 1. t
=%, I, c/='l#,n/=' 1j signal' 1 each (Nando game) 34-R, 34-G, 34
-B to the other input terminal of (B).
L K +R +G-1-B') = '''1'1' Signal is applied to one input terminal of the NAND gates 34-R, 34-G, and 34-B, so that each of the NAND gates 34- R,
The rings of 34-G and 34-B were determined respectively. 1.
0' and O signals to respective amplifier circuits 30-R and 30-.
G, '3O-BK' is applied to the collector of the output stage NPN transistor (denoted as Tr-2 in FIG. 5).

As a result, in the amplifier circuit 30-R, the R signal -t from the chroma IC2h is applied to the pace of the transistor Tr-1, and the signal 7'( A voltage is output, and this voltage is applied to the transistor Tr-2 of the amplifier circuit 30-.Furthermore, a 10' signal is applied to the transistor Tr-2 from the inverter 32-k. being applied,
The transistor T r -2 (6be7, the potential decreases and is cut off, so that this transistor T r
The collector output of -2 is approximately zero as shown in Fig. 7 (b+).Furthermore, this collector output is
The collector voltage, that is, the output terminal 33-k of the amplifying circuit 30-R is applied with a high voltage, that is, the voltage of the text character as shown in FIG. 7 fcl. A voltage corresponding to the red component of the area appears.

On the other hand, in the amplifier circuit 30-G, the transistor T
A G signal from the chroma IC is applied to the base 7 of r-1, and the collector of the transistor Tr-1, therefore the base of the transistor Tr-2, and the amplifier circuit 3 described above.
In the same manner as in 0-k, a voltage corresponding to the G signal appears, and a 0 signal is applied from the inverter 32-G to the pace of the transistor Tr-2, and the transistor 7
Therefore, the collector output of this transistor T r -2 becomes In in the same way as the collector output of the transistor T r -2 in the above-described amplifier circuit 30-k. Furthermore, a Nant gate 34-G is connected to the collector of this transistor Tr-2.
A 0 signal is applied from the amplifier circuit 30-k, and the voltage at the collector output of the transistor T r -2, and therefore at the output terminal 33-G, is approximately zero, unlike the case in the above-described amplifier circuit 30-k. That is, of the green component of the television image signal, a portion corresponding to the text character portion (red component) to be superimposed is killed.

Also, in the amplifier circuit 30-B, the signal 0 is applied from the NAND gate 34-B to the collector of the output stage transistor Tr-2 in the same way as in the amplifier circuit 30-G described above. Among the blue components of the television image signal, a portion corresponding to the text character portion (red component) to be superimposed is killed.

As a result, during the period T1, the transistor (not shown) connected to the R cathode terminal of the CRT 13 in the drive circuit 12 is connected to the output terminal 33-k of the superimposing device (
R+R)' is turned on, while transistors (not shown) connected to the G and B cathode terminals of the CRT 13, respectively, are output terminals 33-G and 33-.
B-katana et al. receive a signal of almost zero and are turned off. Therefore,
On the screen of the CRT 13, as shown in area A in FIG. The 0 component and the blue component are killed as described above, and this overlapping portion correctly displays the red text character portion without color mixing.

Next, the text character part is green, i.e. R/=0
, G'-1', B'-0'11 The operation for period T2 will be explained. Note that it is assumed that BLK="0".

In the period T2, the control signal generation circuit 31 controls each inverter 32-
R, 32-C;, common to 32-B, CB L K
10R'10G'10B') = ""o'10'"0'0'"
1'+o'1'o'-""1' signal is applied, while (BLK+R
'10G'+B') -'''1', Oj Hi/
=′″0 is applied, and each Nant gate 34-R, 3
11' and i'- to the two input terminals of 4-B, respectively.
Apply 129%11 and B=1'e. Therefore, from each Nant gate 34-G, 34-R, and 34-B, each amplifier circuit 30-G, 30-R, and 30-B
Signals 1, 0 and 0' are applied to the collectors of the output stage transferer T r -2 in and.

The amplifying circuit 30-G has a narrow output terminal in the same manner as the amplifying circuit 30-R in the period T1 described above.
The collector outputs of 0- and 30-B are both substantially zero, so the output terminals 33-R1 and 33-B are both substantially zero.

In addition, in this period T2, as an example of the operation for suppressing the above-mentioned color mixture, the output stage transferer Tr-2(7) ]V lid output in the amplifier circuit 30-R is
FIG. 7 (shown in C1).

As a result, in the drive circuit 12, the transifter (not shown) connected to the cathode terminal of the CRT 130G is turned on, and the transistors (not shown) connected to the R and B cathode terminals of the CRT 13 are both turned off. Ru.

Therefore, on the screen of the CRT 13, as shown in area B in FIG. 8, in the same manner as in the above period 115T1,
In the television image, the green part of the text is
The red and green components of the television image are displayed in a superimposed manner without being mixed with each other.

Furthermore, in period T3, the text character part is blue, i.e., R'-10', c'=”0#, B/=%
1# and BLK, = Q, then
In the same way as in the periods T i and T 2 described above, the blue portion of the text character is displayed superimposed on the television image without mixing with the red and green components of the television image.

In addition, during this period T3, as an example of the operation for suppressing the above-mentioned color mixture, the collector output of the output-stage transferer T r -2 in the amplifier circuit 30-R is shown in FIG. 7 (C1).

On the other hand, in the above period T1, along with the signal representing the red component of the text character part, the green component of the character part, G'-'''1' representing the blue component, and B=
When the l signal is applied to the control signal generation circuit 31, each amplifier circuit 30-R,
Output stage transferer T in 30-G and 30-B
At the collector output of r −2, there is a Nant gate 3, respectively.
From 4-R, 34-G, 34-B 1. 1. 1
The signal is applied to the output terminal 3 without color mixing with the color signal of the television image from the text character part.
3-R, 33-G, and 33-B have (R + R
), (G0G'), CB0B) are expressed. As a result, based on the operation of the drive circuit 12 described above, CR
On the screen at T13, a portion of the television image corresponding to the text character is displayed in white.

This state is shown by region C in FIG.

Further, for example, when a BLK=l signal is output from a blanking generation circuit (not shown) provided in the teletext receiver during the period T1,
This signal BLK=l is transmitted to the control command signal generation circuit 3.
In addition to 1, the voltage is also applied to the above-mentioned chroma IC, and the chroma I
The output of the demodulated color signal from C stops. As a result, on the screen of the CRT 13 mentioned above, as shown by the area in FIG.
The red part of the Tomo text characters is displayed against a black background.

Color signals R, G, B to each amplifier circuit 30-R, 30-C;, 3Q-B from the chroma IC in the television receiver.
input is prohibited, and the BLK-'1' signal is applied to the control signal generating circuit 31 from the blanking signal generating circuit (not shown) in the teletext receiver described above. = Also, the R signal, C/signal, and B' signal representing the text characters received by the teletext receiver are applied to the control signal generation circuit 31 from the teletext receiver.

The text character part above is red, i.e. k'-'''1'
.

If G'-ゞd', B'-''o', then the control signal generation circuit 31, (B L K+R'+G'+B') =
'C'''1#10Y+0+0)='l' signal is
Inverter 32-R, 32-G, 32-B? via r.
It is applied to the vane of the transistor Tr~2 of the output stage in each layer @1m paths 30-R, 30-G, and 3Q-B.

Also, the above (B L K + R' + G' + B') = '
1' signal is connected to each Nantes gate 34-R, 34-G, 34-
B is applied to one input terminal of the Nant gate, and from the control signal generation circuit 31 to the other input terminal of each Nant gate,
R=O, G=l, B'=', respectively.
1' is applied. Therefore, these Nando games) 34
-R.

34-G, 34-J)>1), Output signal S '1',
″o4).

0 is for each amplifier circuit 30-R, 30-G, 30, respectively.
-B is applied to the collector of the output stage transistor Tr-2.

As a result, (R+R') = (0+R') = R
/ appears, while substantially zero voltage appears at both the other output terminals 33-G and 33-B. These output signals,
R', 0. Oi, the upper i drive 171 [ilu path 12] is applied to the screen of the CRTI 3, so that the screen of the CRTI 3 has a black color in the pixel area displaying the part of the text character as shown in the area E [in FIG. The red part of the text characters used as the background is displayed.

Also, the text character part of the teletext receiver crab is white, i.e., k'='''1', c'-'l', B'
-1, or blue, i.e. k'-10'
, G'='0', B-ゞI', or green, i.e. 1. /= +01, G/-%,? , B
/-*or teme, area F and G in FIG. 8, respectively.

It is displayed on the screen of the CRTI3 as shown in H.

In the PIC mode, the control signal generation circuit 31 is turned off, and the control signal generation circuit 31 and the like are (B L K0B'+R0B).
The ij/, :/, ii/ signals are not output. Therefore, each amplifier circuit 30-R, 30-G.

30-B is the chroma IC power in the TV receiver.
The R signal, G signal, and B signal representing these television images are received, and these color signals are amplified by an amplification factor of -1. In other words, each color signal is output to each output terminal without changing these color signals. C via 33-R, 33-G, 33-B
The voltage is applied to the RT drive circuit 12. Therefore, only the color television image received by the television receiver is displayed on the screen of the CRTI 3.

Next, the chroma IC generates three color difference signals (k-Y),
FIG. 9 shows a specific example of a superimposing device in the case of a color signal demodulation circuit of a type that outputs (G-Y), (B-Y) and a luminance signal Y.

Note that in FIG. 9, parts equivalent to those in FIG. 5 are given the same reference numerals and explanations will be omitted.

In FIG. 9, as described above, amplifier circuits 30-R, 30-G, and 30-B are equivalent to the basic circuit 15.

30-Y is provided, and the base 7 of the transistor T r-1 of each input stage in these amplifier circuits has the following:
From the chroma IC in the receiving device 12 (see FIG. 3),
Color difference signals (R-Y), (G-Y), (B-Y) and luminance signal Y generated by a known method based on demodulated color signals of a television image received by the television receiver are Connected to input.

In FIG. 9, the control signal generation circuit 31 is shown surrounded by a chain line.
For example, a teletext receiver (not shown) has a 'signal', a 'G' signal, and a 'G' signal to represent text characters.
Input terminal 36- connected so that the B' signal is input.
R, 36-G, 36-B are connected to open collector type Nant gates 34-R, 34 via open collector type inverters 37-R, 37-G, 37-B, respectively.
-G and 34-B are connected to the other input terminals. Also, a blanking signal BLK is sent from the teletext receiver.
The input terminal 36-BLK, which is connected so as to be inputted thereto, is connected to one input terminal of the two-man powered Nantes gate 39 via the inverter 38-BLK, and the input terminals 36-R, 36- G, 35-B are respectively,
Inverter 38-R.

33-G, 38-Bfjr: Commonly connected to the other input terminal of the Nantes gate 39 through. The output terminal of the Nantes gate 39 is connected to one input terminal of the aforementioned Nantes gates 34-R, 34-B, and 34-B.
Commonly, (BLK-)-R'-1-G'-1-B
' ) is connected to input the signal. The output terminal of the NAND game) 39 is connected to the amplifier circuit 30-Y via an open collector inverter 43 and a variable resistor 44.
It is connected to the collector of the transistor Tr-2 in the output stage. Further, one input terminal of the Nant gate 39 is connected to the collector of the output stage transistor T r -2 in the amplifier circuit 30-Y via an inverter 40, a gin collector type inverter 41, and a variable resistor 42. ,ru.

In the amplifier circuits 30-R, 30-G, and 3O-BK, the collectors of the output stage transistor 7 T r =2 are a resistor 45-R and a capacitor 46-R, respectively.

Nant gate 34-R via a filter circuit consisting of 45-G and 46-G, 45-B and 46-B.

34-G, 34-B, and the output terminals 33-R, 33-G, 33 in the superimposing device.
- BK is connected. Further, the collector of the output stage transistor Tr-2 in the amplifier circuit 30-Y is connected to the output terminal 33-Y via a collector-grounded L*PNP) range metal 4F0 base-emitter.

Now 50 is the output terminal 33-R, 33 in the superimposing device.
-G, 33-B is a clamp circuit for limiting the output level of the output terminals 33-R, 33-G, 33-B to a predetermined level, as shown in FIG.
Diodes 51-R and 51 connected to 33-B, respectively.
-G, 51-B, a transistor 52 with a common collector connected commonly to the anodes of these diodes, and the control signal generating circuit 31 connected to the base of the transistor 52.
(R+
G+B) Variable resistor 5 connected so that the signal is input
3, an open collector type inverter 54, and an inverter 55.

The operation of the superimposing device having the above configuration is basically the same as the fifth one described above.
As in the case of using the system shown in the figure, the text characters from the teletext receiver to be superimposed on the television image received by the television receiver are in MIX mode, TEX
In T mode or PIC mode, the text characters are displayed superimposed on the screen of the CRT 13 without color mixing with the television image. The operation of this superimposing device is almost the same as that of the device shown in FIG. 5 described above, and the explanation of the operation will be omitted.

As mentioned above, in the superimposing device shown in FIGS. 5 and 8, the first logic gate 23 (inverter 32-R
, 32-G, 32-8) of the text character to be superimposed, the amplifier circuit (3
0-R, 3Q-G.

Among the color signals representing the television image inputted to 30-B), the operations of killing the color signal of the portion corresponding to the text characters and superimposing or mixing the text characters on the television image are simultaneously performed. The text characters to be superimposed can be reliably superimposed on the television image on the television receiver's video screen while preventing color mixing with the red, green, and blue components of the television image. can be displayed clearly.

1. In the superimposing device having the above configuration, the portion of the television image signal on which text characters are to be superimposed is cut off, and the television image signal and the text characters are mixed as in the conventional method. In addition, since this can be done with an integrated amplifier circuit (30-R, 30-G, 3O-B) without using separate switching means and mixing means, there is no need for connecting leads between the component parts. The length can be made as short as possible, and the noise induced in the color signals transferred between the components can be suppressed accordingly.
A high-quality image can be projected on the screen of a television receiver.

Furthermore, the superimposing device with the above configuration simply connects the input terminal of the amplifier circuit in the superimposing device and the output terminal of the device to the chroma IC in the existing television receiver and the drive circuit for driving the CRT, respectively. It can be easily installed in a so-called plug-in manner without changing the circuit configuration provided in the chassis of the television receiver.

In the above-described embodiment, the case where color text characters are superimposed on a color television image has been described. However, when monochrome text characters are superimposed on a monochrome television signal, the superimposition device has two TV sets. The demodulated image signal of the monochrome television signal is commonly applied to the input terminals for RlG and B of the television image signal, and the input terminal for R, G, and B of the text character signal in the control signal generation circuit is applied in common. If a monochrome text character signal is applied in common, the superimposition device can be used in both color and monochrome applications.

As is clear from the above description, according to the present invention, while applying a demodulated television image signal to the input terminal of an amplifier circuit configured using at least two transistors so that the amplification factor is 1, A first control circuit generates a cutoff signal based on superimposition video information such as characters and graphics, and completely cuts off a portion of the television image signal that corresponds to the superimposition video signal, by baking the transistor in the output stage of the amplifier circuit. and applying a signal representing the superimposition video information generated by the second control a circuit to the output terminal of one transistor of the output stage,
Since the amplifier circuit simultaneously cuts off the portion of the television image signal that corresponds to the video information signal for superimposition and mixes the P-processed television image signal and the video information signal for superimposition, it is possible to Displays the above-mentioned video information such as characters and graphics on the video screen of a television receiver together with the television image signal or alone, with less noise and more clearly than with other types of superimposing devices. It has the great advantage of being possible.

Alternatively, the input terminal of the amplifier circuit may be simply connected to the output terminal of a demodulation circuit for a television image signal in an existing television receiver, and the output terminal of the amplifier circuit may be connected to the video device in the television receiver. Another advantage is that it can be easily attached to a television receiver by simply connecting it to the input terminal of the television receiver without changing the circuit configuration of the television receiver.

[Brief explanation of the drawing]

1 and 2 are diagrams showing the basic configuration of a typical conventional superimposing device, and FIG. 3 shows the overall configuration of a television system when the superimposing device according to the present invention is applied. 4 is a block diagram showing the basic configuration of the superimposing device shown in FIG. 3, and FIG. 5 is an electric circuit diagram showing an example of a specific circuit of the superimposing device shown in FIG. Figure 6 shows the function of the electrical circuit shown in Figure 5.
I T" CH) figure, Figure 7 (al, (bl, 2-work (
C1 is a signal waveform diagram for explaining the operation of the amplifier circuit in the circuit of FIG. 5, and FIG. 8 is a signal waveform diagram displayed on the video screen of a television receiver when the superimposed bag @ of FIG. 6 is used. FIG. 9 is a diagram for explaining the image projection mode.
Another specific example of the superimposition device according to the present invention will be shown! It is an air circuit diagram. 10... Superimposition device according to the present invention, 11... Receiving device in a television receiver, 12... CR
Driving circuit for T, 13... Color CRT, 15
...Basic circuit of the superimposition device according to the present invention, 16...
・PNP) transistor, 17... NPN) transistor, 23... first logic game) IC125...
Second logic gate IC1 30-R, 30-G, 30-B, 30-Y...Amplification circuit, 31...Control signal generation circuit, 32-R. 32-G, 32-8, 32-Y...Inverter, 33
-R, 33-G, 33-B, 33-Y...output terminal,
34-R, 34-G, 34-Y...Nant Gate,
36-BLK, 36-R, 36-G. 36-B... Input terminal of control signal generation circuit, 50.
... Clamp circuit, R, G, B... Red demodulated television signal. Green and blue components are fully displayed. Color signal, Y... Luminance signal, R-
Y, G-Y, B-Y...color difference signal, B L K
,,. Blanking signal, R, G, B... A color signal that represents the red, green, and blue components of a text character or figure. B,...,F,G...A region corresponding to one pixel on the video screen. Figure 1 Figure 2 Figure 3 Figure 5

Claims (1)

[Claims] (1) An amplifier circuit that is configured to have an amplification factor of 1 using at least two transferers and that inputs a demodulated television image signal to the base of a transistor in the input stage; a first control that inputs a cutoff signal generated based on the video information signal for superimposition and that cuts off a portion of the television image signal corresponding to the video information signal for superimposition to the base of the transistor in the output stage of the amplifier circuit; and a second control circuit that applies a signal representing the superimposition video information to the output terminal of a transistor in the output stage of the amplifier circuit, and controls the image of the television receiver based on the output of the amplifier circuit. A text/graphic signal superimposition device characterized in that superimposition video information is projected on a screen together with television image information or alone.