JPH01309590A - Onscreen mixing circuit - Google Patents

Abstract

PURPOSE:To synthesize character multiplex signals and onscreen signals with an inexpensive simple circuit by resistance-coupling the R, G and B output signals of a first two-input AND TTL circuit and the respective output signals of a second two-input AND TTL circuit and a three-input AND TTL circuit and outputting the resistance-coupled signal. CONSTITUTION:The title circuit is equipped with a two-input AND TTL circuit 1 to input onscreen R, G and B signals and an onscreen blanking (O-BLK) signal, waveform-shape the signals, and output the respective signals, a two-input AND TTL circuit 2 to input character multiplex R, G and B signals and the polarity-inverted O-BLK signal, a three-input AND TTL circuit 3 to input the character multiplex R, G and B signals, the polarity-inverted O-BLK signal, and a character multiplex half luminance signal, and an output circuit to mix the outputs of the respective AND TLL circuits by resistance-coupling the outputs and output the mixed output. Thus, the character multiplex signals and the onscreen signals can be mixed with the simple circuit and can be supplied inexpensively by using the advantage of a character multiplex built-in television.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application 2-=-/ The present invention relates to an on-screen mixing circuit for a television receiver with built-in character multiplexing.

At the beginning of the prior art, character multiplexing decoders were formed separately for television receivers in the form of adapters and sold separately. Therefore, today's television receivers with built-in character multiplexing are
It is simply a television with a built-in character multiplexing adapter.
The on-screen mixing circuit switches between the on-screen signal and the character multiplex signal using an integrated switching circuit 30 as shown in FIG.
I was adjusting the signal.

That is, the on-screen blanking signal (hereinafter 0
-BL) and 0-BL, an output signal is obtained from the output terminal of the switching circuit 30, which serves as an on-screen signal only during the period of 0-BL, and otherwise becomes a character multiplex signal. Ta. Although not shown, this signal is switched to an RGB signal from television broadcasting at a subsequent stage and displayed on the screen. In FIG. 3, the switching circuit 30 that switches between the on-screen signal and the character multiplex signal is 1.2
・The character multiplexed RGB signal is input to pin 3, and the on-screen RGB signal is input to pins 11 and 12 @ 13.
Character multiplexing RG by signal applied to 0-BL pin 4
B signal and on-screen RGB signal are switched, and 5.
A character multiplex signal combined with an on-screen signal is output from pins 6 and 8. This signal is converted into the television's RG B from the 0-BLK signal and the character multiplexed Ys signal in the subsequent stage.
Switched with signal.

Problem to be Solved by the Invention However, this character multiplexed RGB signal is composed of a full brightness signal, a half brightness signal, and an all black signal (no signal state), and as shown in FIG. This signal indicates the presence or absence of a signal, and is made up of two signals indicating the IT LIT level at half brightness and an RG-8 signal. That is, the signals are processed in the character multiplexing circuit 40 and are applied to the switching circuit 30 in FIG. 3 as R, G, and B signals. In FIG. 4, 41 and 42 are TTL AND circuits, and 43 is an emitter follower IC. The R signal is input from pins 10 and 12 of the TTL AND circuit 41, and the buffered R (word) is output from pin 11. On the other hand, two signals are applied to pin 9, and the AND output is output from pin 8. This output (pin 11 and pin 8) is mixed by resistors R1 and R2, input to pin 10 of emitter follower IC43, and output from pin 4 as a character multiplexed R signal.G signal. The B signal is processed in the same way and becomes the character multiplexed R, G, and B signals.In this way, in the past, the character multiplexed signal was made into a complete signal and then the on-screen signal was added, so the circuit was complicated and the character The advantages of multiple built-in televisions were not being taken advantage of.

Therefore, the cost was also high.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention provides a television receiver with a built-in character multiplexing circuit that can synthesize a character multiplexed signal and an on-screen signal using an inexpensive and simple circuit.

Means for Solving the Problems The on-screen mixing circuit of the present invention is a two-input AND circuit that inputs on-screen 5-peno-lean R, G, B signals and on-screen blanking signals, shapes the waveforms, and outputs the respective signals. TTL circuit and character multiplex R, G
, a two-input AND TTL circuit that receives the B signal and an on-screen blanking signal with inverted polarity as input, a character multiplex R, GSB signal, an on-screen blanking signal with inverted polarity, and a character multiplex half-brightness signal. A 3-input AND TTL circuit with a signal as input, and each AND
It is provided with an output circuit that mixes the outputs of the TTL circuits through resistance coupling and outputs the mixture.

Operation The on-screen mixing circuit of the present invention takes advantage of the advantages of televisions with built-in character multiplexing, can mix character multiplex signals and on-screen signals with a simple circuit, and can be supplied at low cost.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to FIGS. 1 and 2.

In FIG. 1, as an input signal, on-screen RG
There are a B signal and a 0-BL signal, as well as a character multiplexed RGB signal and two signals (character multiplexed half-brightness signal). On-screen R, G, B signals and 0-BLK signal are 2-input AN
The signals are input to the D TTL circuit 1, buffered, and output from pins 8, 11, 3, and 6, respectively. 6
The 0-BLK signal output from the pin is connected to the subsequent circuit and at the same time is inverted by transistor 4, and is connected to pins 4, 9, and 12 of 2-input AND TTL circuit 3 and 3 of 3-input AND TTL circuit 4. .11.Input to pin 13. . 13.10.
Character multiplexed R, G, and B signals are applied through pin 5. Furthermore, character multiplexed R, G, and B signals and two signals are applied to the remaining two inputs of each AND game (HR, HG, and HB) of the 3-input AND TTL circuit 3. Therefore, 0-
The period for BL is AND all AN of TTL circuit 3.4
The DTTL output is at the low level, and the on-screen RGB signals are output at levels 7...-7 determined by the surrounding resistance values.

In addition, the character multiplexed R signal is input to pin 13 of 2-input AND TTL circuit 2 and pin 10 of 3-input AND TTL circuit 3, and pin 11 of 2-input AND TTL circuit 2 receives characters excluding the 0-BLK period. Multiple R signals are output. The 9th pin of the 3-input AND TTL circuit 3 has 2
A signal is input, and an R signal of character multiplexing excluding the 0-BLK period and the half-brightness period of character multiplexing is output to pin 8. This 2-input AND '1'' 11 of TL circuit 2
The output of the pin and the output of the 8th pin of the 3-input AND TTL circuit 3 are mixed via a resistor to form a character multiplexed R signal, which is further mixed with an on-screen R signal and connected to a subsequent circuit. FIG. 4 shows an example of the waveform of this signal.

Thereafter, the G and B signals are similarly processed and connected to the subsequent circuit, where they are switched to the television signal and displayed on the screen.

Effects of the Invention As described above, the on-screen mixing circuit of the present invention takes advantage of the fact that text multiplex signals and on-screen signals coexist in the same device, which is an advantage of televisions with built-in text multiplexing, and enables text multiplexing signals to be produced at low cost. It is possible to mix the on-screen signal and the on-screen signal, and is extremely advantageous in terms of cost.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an on-screen mixing circuit according to an embodiment of the present invention, FIG. 2 is a signal waveform diagram for explaining the operation of FIG. 1, and FIG. 3 is a conventional on-screen signal and character diagram. FIG. 4 is a circuit diagram of a conventional character multiplex signal processing circuit. 1.2...2 input AND TTL circuit, 3...3 input AND TTL circuit, 4...transistor.

Claims (1)

[Claims] A first two-input ANDTTL circuit that inputs on-screen R, G, and B signals and an on-screen blanking signal, shapes the waveform, and outputs the respective signals, and a character multiplexer R.
, G, B signals and the above on-screen signal whose polarity is inverted.
Second 2-input AND T with blanking signal as input
a TL circuit, a three-input AND TTL circuit which receives as input the character multiplex R, G, and B signals, an on-screen blanking signal whose polarity is inverted, and a character multiplex half-brightness signal;
R, G, B output signals of the first 2-input AND TTL circuit and the second 2-input AND TTL circuit and 3-input AND
An on-screen mixing circuit comprising an output circuit that resistively couples and outputs each output signal of a TTL circuit.