JPS6016154B2 - color television receiver - Google Patents

Description

[Detailed description of the invention] The present invention relates to a color television receiver.

Currently, various color television systems are being adopted in countries around the world, and these are mainly based on NT in countries such as the United States and Japan.
It is broadly classified into the SC system, the PAL system of West Germany, Italy, etc., and the SECAM system of East Germany, Saudi Arabia, etc., and it is well known that these systems are not compatible with each other. For this reason, in order to receive television broadcasts from the countries they are visiting, for example, on a ship on a foreign route, it is necessary to install multiple receivers dedicated to each of the above systems, which is therefore economically disadvantageous. This is extremely inconvenient in terms of target or installation location. This also applies to cases where television broadcasts of different systems can be received in rural areas near borders, or when a receiver purchased in another country is brought back to the home country. Therefore, the present invention focuses on the fact that the vertical scanning frequency differs depending on the television system, and by detecting the vertical scanning frequency of the received television signal and automatically switching each circuit in the receiver, A color television receiver capable of receiving television broadcasting is realized with a relatively simple configuration.
An embodiment of the television receiver of the present invention will be described below with reference to the drawings, and the television broadcasts targeted in this embodiment are as shown in the table below.

Figure 1 of Table 1 shows the schematic configuration of the receiver described below. What requires special attention in this diagram is that the tuner is configured to be able to receive each broadcast listed in Table 1, and that Each received television signal is converted into an IF (intermediate frequency) signal that has the same audio carrier frequency, i.e., 33.4M ratio, and this IF signal is converted into a single wideband (5.8M ratio) VIF amplification signal. Detection of the frequency (vertical frequency) of the vertical synchronization signal separated and derived from the VIF detection output of the VIF circuit 2 by the synchronization separation circuit 13. It is detected by the circuit 15, and the detection output is used to control the AFT (automatic fine tuning) circuit 3 and Sm (audio intermediate frequency).
The point is that the switching circuit 17 for switching the circuit 4, the video amplification circuit 6, the PAL color signal circuit 8, and the vertical deflection circuit 14 is slowly operated.

The functions of the other circuits in FIG. 1 are shown in the blocks. Further, 19 is a picture tube, and 18 is a speaker. FIG. 2 shows the detection circuit 15 and the switching drive circuit 16.
details.

That is, the positive vertical synchronization signal derived from the synchronization separation circuit 13 in FIG. 1 is applied from the terminal T in FIG.
NTSC signal (60
Hz) and PAL and SFCAM signals (5 Hz), the pulse width is 2 hsec. The peak value is 18V
is converted into a negative pulse of After the polarity of this pulse is inverted by TR6, it is converted into a vertical frequency mirror-tooth wave by a Pootstrap circuit composed of TR7, TR8, and TR9. At that time, if the vertical frequency is same day z, it will be about 14V.
A sawtooth wave with a wave height of
A sawtooth wave with a wave height value of is obtained. TR. 50H on the base of
z, the pulse width is approximately 2 hsec. In this case, a positive pulse with a peak value of 2V appears, but such a pulse does not appear in the case of 6 plates Z. Then, the pulse for this case of 5 plates z is amplified by TR,o, and TR, . After the polarity is inverted at , it is converted to DC by TR,2, capacitor C2, and resistor R, and this DC positive voltage turns on TR,3. Therefore, the collector of TR3 is connected to the PAL signal and SCAM.
For signal (50s), it is OV, and for NTSC signal (60s), it is OV.
In the case of (Se), it becomes 118V. And this +18V
, OV are used to turn on and off each switching transistor (Fig. 3) corresponding to the switching circuit 17 of Fig. 1. FIG. 3 shows details of each circuit switched by the switching circuit 17 of FIG. 1, and here, parts corresponding to those in FIG. 1 are given the same figure numbers.

In this figure, V'Circuit 2 uses a Mitsubishi Electric IC: M518, and the IF signal from tuner 1 in Figure 1 is applied to pin No. ■, and is taken out from pin No. ■. The detected output is inputted via the emitter follower TR, 8 to a video amplifier circuit 6, a SECAM color signal circuit 7, a PAL color signal circuit 8, and an NTSC color signal circuit 9, respectively.

In addition, AFT detects the intermediate frequency video carrier frequency.
The AFT circuit [3 in Figure 1] that generates voltage is also built into 2 for the VIF circuit in Figure 2, and the
When a DC voltage of 2.0 to 6.8 V is applied to pin No. 2, an AFT voltage is derived to pin No. 2.
By the way, in the present invention, as mentioned above, the local oscillation frequency of the tuner is adjusted so that the intermediate frequency audio carrier frequency is the same frequency P, 33.4 MHz, for each method in Table 1. Therefore, the audio intercarrier frequency is 4. The NTSC system, which is the rule mz, and it
．． In PAL and SECAM systems, which are same-day z, the intermediate frequency video carrier frequencies are naturally different.

Then, the above-mentioned V "Circuit 2 is connected to the video carrier frequency of PAL and SECAM." The AFT operation is performed based on the normal position. Therefore, it is necessary to stop the AFT operation when receiving an NTSC signal. That is,
At the time of the NTSC signal, the collector voltage of TR, 3 in FIG. 2 is 118V as mentioned above, and this voltage makes the switching transistors TR, 4 in FIG. 3 conductive, so the pin No. 2 of IC2 becomes OV, Therefore, this IC does not perform AFT operation. On the other hand, PAL and SECAM
At the time of signal, the collector voltage of TR,3 is OV, so
TR, 4 is off, so when the AFT switch S is on, 112V is applied to the No. ■ pin of IC2 through the resistors R2, R.
Since a voltage of about 3.5V divided by 3 is applied, the AFT voltage is output from pin #2 of this IC2. In addition, when the AFT switch 6 is off, the pin No.
Since V is directly applied, the above AFT voltage is not generated. In addition, the SIF signal is
By connecting the tuning circuit K of the audio intercarrier between the No. 2 pin of No. 2 and the power supply +12V, the signal is output from the No. 2 pin.

For this reason, it is necessary to switch the tuning frequency of the tuning circuit K so that it matches each audio intercarrier frequency when receiving each system. That is, during PAL and SECAM signals, the OV from TR, 3 in FIG. 2 is applied to the base of the switching transistor TR, 5, so this TR, 5 is off, and therefore the switching diode D3 is also off. Therefore, the tuning circuit K
is 5 mainly due to capacitor C4 and inductance L.
．． It is tuned to 9MHz. On the other hand, the NTS
At the time of the C signal, the previous TR, 5 is turned on by the 118V from the TR, 5 (the cathode side of D7 is 112V or less), and therefore, D3 is also turned on.
The tuning circuit K is tuned to 4.8 MHz by adding a capacitor C5 to C4 and L described above. Then, the SIF signal of 5.8 MHz and 4.9 M ratio derived from the No. 1 pin of the IC2 in this manner is introduced into the S-circuit 4 via the capacitor C6. The Sm signal input to the SIF circuit 4 is 5.8M.
In the case of Hb (PAL and SECAM), the S signal passes through the S frequency conversion circuit 4a, which functions as a mere amplifier, and the S
It is input to 4b for the IF circuit, but the 4.8M ratio (NTS
In the case of C), the frequency conversion circuit 4a has a S ratio of 5.9M.
The signal is converted into an m signal and input to the IC 4b.

That is, during the PAL and SECAM signals, the switching TR 5 is off as described above, so power is not supplied to the IMHz oscillator 4c, and therefore the frequency conversion circuit 4a functions only as an amplifier. , N.T.
Since the above TR, 5 is turned on at the time of the SC signal, 112
V power supply is connected to lines 20, 21 and smoothing capacitor C7
is supplied to the oscillator 4c via diode ○4,
Therefore, the circuit 4a functions as a frequency conversion circuit. Then, in this way, the SIF circuit IC4b
The SIF signal introduced into is amplified here and then subjected to FM detection, and the detected output is introduced into the audio output circuit 5 shown in FIG. Incidentally, LA1320 manufactured by Tokyo Sanyo Electric was used here as the above-mentioned Sm circuit IC4b. Next, frequency switching of the color subcarrier trap is required in the video amplifier circuit 6 for PAL and SECAM signals and for NTSC signals.

That is, the color subcarrier is 4.433 for the PAL signal in Table 1.
MHz, and 4.4062 for SECAM signals
9 MHz and 4.29 digits, and these are trapped by the second video amplifying TR of the video amplifying circuit 6, and a ceramic filter connected to the base of the video amplifying circuit 6. On the other hand, the color subcarrier of the NTSC signal is 3. Since the frequency is irregular MHz, when the NTSC signal is received, switching TR, 7 is turned on, and 3. Isomisaki Z's trap is now inserted. At this time, for the NTSC signal, the trap frequency of the ceramic filter is near the audio intercarrier frequency of 4.8 MHz, which is outside the video band, so there is no need to separate it. Next, switching of the color signal circuits 7, 8, and 9 will be explained.
I will explain about it.

That is, this ICII uses a TA762 tsubo made by Tokyo Shibaura Electric, which connects the B-Y and R-Y demodulated outputs from the first color signal circuit to pins ■ and ■, and connects them to the second color signal circuit. B-Y and RY demodulated output from the signal circuit
It is possible to connect to pin No. 2, and which one is accepted is determined by the magnitude of the DC exposure voltage applied to pin No. 2 of the IC. Therefore, for this matrix circuit 11, a SECAM color signal circuit 7, a PAL color signal circuit 8, and an NTSC color signal circuit 9 [hereinafter, simply a SECAM circuit and a PAL
The R-Y and B-Y demodulated outputs from the NTSC circuit and NTSC circuit are connected as shown in the figure, and separately from the S
An ECAM color carrier signal detection circuit 10 is provided, and the output voltage of this detection circuit is applied to the pin No. 11 above.

Here, each of the above-mentioned color signal circuits 7 to 9 includes all color signal-related circuits from the stage after the VIF circuit 2 to before and after the matrix circuit 11, that is, a color band amplifier, a color demodulator, a color killer circuit, m It includes circuits, etc.

In particular, PAL circuit 8 is equipped with Tokyo Shibaura Electric's I
C: TA719 group is used, and this IC is its ■
When a voltage of about 112V is applied to the pin number, the IC
Since the color killer circuit inside is activated, the @ pin of this IC is connected to the aforementioned line 201 via a current limiting resistor R5 and a switching diode D5. Therefore, when the detection circuit 10 detects the color carrier signal of 4.40 MHz and 4.28 MHz inserted into the horizontal blanking period of the SECAM signal, this detection circuit detects 2. Since a suitable positive voltage within 8-10V is derived, the matrix circuit 11 will operate only on the demodulated output of the SECAM.

On the other hand, in the case of a PAL signal, the burst signal, that is, the 4.43 MHz signal inserted into the horizontal blanking period of the signal, is not detected by the detection circuit 10, so the output of this detection circuit becomes OV, and this NTS in case
Since the color killer circuit in C circuit 9 operates, PAL
Only the demodulated output of is introduced into the matrix circuit 11. In addition, when the NTSC signal is present, the switching transistor TR,5 is turned on and 112V is applied to the pin #2 of the PAL circuit IC8, so the color killer circuit in this IC8 operates, and also at this time, the color carrier Since the output of the detection circuit 10 is OV, NT
Only the demodulated output of the SC will be introduced into the matrix circuit 11. Next, NTSC signal time, PAL and SEC
It is the deflection circuit that requires switching at the time of the A signal, but
Here, only the vertical deflection circuit 14 is switched.

This is because the horizontal scanning frequency is 15.7 for NTSC signals.
3 rounds, 15.62 for PAL and SECA signals
This is because, if a horizontal oscillator (not shown) with a pull-in range of about ±40 centimeters is used, this oscillator can be operated at both of the above-mentioned horizontal scanning frequencies. The vertical deflection circuit 14 uses Tokyo Sanyo Electric's LA1463 as an IC for vertical oscillation and vertical drive, and the power supply voltage is supplied to the No. ■ pin of this IC 14, and the vertical oscillation frequency is supplied to the No. ■ pin. The amplitude of the drive voltage waveform is determined by the connected time constant circuit, and the amplitude of the drive voltage waveform is determined by the potential applied to the pin No. 2.

Further, the vertical synchronization signal from the synchronization separation circuit 13 shown in FIG. 1 is applied to the No. 2 pin of the IC 14. Therefore, first, a switching diode D6, resistors R6 to R8, a variable resistor VR, and a capacitor C9 are connected between the line 20 and the 112V power supply to switch the oscillation frequency.

That is, for PAL and SECAM signals, R6 to 9, VR
,,The oscillation frequency determined by C9 is set to 50Hz, and when TR,5 is turned on during the NTSC signal, D6 is also turned on [The cathode side of D6 is connected to IC14 via R7 and R8.
Since it is connected to the pin No. 2 of It's supposed to be. Also, the oscillation frequency is 5
If the vertical deflection amplitude is increased to 6 m from the plate z, the vertical deflection amplitude will be reduced, so in order to correct this, the line 20 and the
A switching diode D7, resistors R9 to R, . , and capacitors C and o are connected. That is, when receiving an NTSC signal, TR, 5 and D7 are turned on and 112V is applied, so the potential at the midpoint of connection between R9 and R,o is higher than when D7 is off, that is, when PAL and SECAM signals are applied. Therefore, the reduction in the vertical deflection amplitude when the voltage applied to the No. 2 pin of the IC 14 increases and the oscillation frequency becomes 6 & is corrected. As detailed above, when the color television receiver of the present invention receives a television signal of a certain format, it detects the frequency of the vertical synchronization signal of the television signal, and uses the detection output to control each of the receivers. Since the circuit is automatically switched, it is possible to receive television signals of various formats, and in particular, when converting each received television signal to an IF signal, the audio carrier frequency Since the frequencies are made to be the same, there is no need to switch the audio trap frequency of the VIF circuit, and there is an advantage that the configuration of the switching circuit is simplified.

Furthermore, in the present invention, the color carrier frequency of the received television signal is determined and the color signal circuit is switched. This means that you can receive any image.

Furthermore, in the present invention, since the tuning frequency of the audio intercarrier tuning circuit connected to the VIF circuit and the on/off state of the audio intercarrier frequency conversion circuit are switched, one SIF circuit can be commonly used for television signals of each system. This simplifies the overall configuration of the receiver.

[Brief explanation of the drawing]

The drawings all relate to the television receiver of the present invention.
2 is a block diagram showing a schematic configuration of the entire receiver, FIG. 2 is a circuit diagram showing details of a vertical frequency detection circuit, and FIG. 3 is a circuit diagram showing details of switching circuits of various parts. 1... Tuner, 2... VIF circuit, 4... SIF circuit, 7... SECAM color circuit, 8... PAL color circuit, evening 9... NTSC color circuit, 10...
・SECAM color carrier signal detection circuit, 15...
Vertical frequency detection circuit. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. A tuner is configured so that it can receive three types of color television signals of different standard formats, and each television signal received by this tuner is converted into an IF signal with the same audio carrier frequency and connected to a single VIF circuit. Detect the frequency of the vertical synchronizing signal separated from the detected output of this VIF circuit, and use the detected output to determine the tuning frequency of the audio intercalary tuning circuit connected to the VIF circuit,
Turns on/off the audio intercarrier frequency conversion circuit, the deflection frequency and deflection amplitude of the vertical deflection circuit, and turns on/off a specific one of the three color signal circuits provided individually corresponding to each television system. A color television receiver characterized in that, at the same time, one of the other two color signal circuits is selected and operated based on the frequency detection output of the color subcarrier signal.