JPS6199475A - Television receiver of multiscanning type - Google Patents

Abstract

PURPOSE:To prevent black parts on a screen from emitting light even if the horizontal frequency of an input signal is changed, by detecting the horizontal frequency of the input signal and controlling the DC potential of a video signal driving a cathode-ray tube in accordance with the horizontal frequency by the detection output. CONSTITUTION:When the video signal of about 33.75kHz horizontal frequency is inputted, three primary color signals are supplied from an RGB process circuit 3 to input terminals 80R, 80G, and 80B and are supplied to cathodes KR, KG, and KB of a cathode-ray tube 6, and the potential of a screen grid G2 of the cathode ray tube 6 is raised in comparison with the case of about 15.75kHz horizontal frequency by a flyback transformer 41. Therefore, the DC potential of the video signal supplied to cathodes KR, KG, and KB is raised by the potential rise of the screen grid G2. Thus, black parts on the screen are prevented from emitting gray light even if the video signal of about 33.75kHz horizontal frequency higher than about 15.75kHz is received.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention can be used to increase the number of scanning lines to 2 in addition to normal television broadcast image reception.
The present invention relates to a multi-scan television receiver capable of receiving video signals of different horizontal frequencies from a converter or the like that performs double conversion.

[Conventional technology]

For example, in an NTSC television signal, an image is formed with a vertical frequency of approximately 6011 z and a horizontal frequency of approximately 15.75 KHz. In response, a conversion device has been proposed that doubles the number of scanning lines through arithmetic processing or the like to improve the quality of the received image. When this device is used, the signal output from this has a vertical frequency of about 6011 z and a horizontal frequency of about 31.5 KHz.

In addition, some so-called high-resolution display computer output signals have a horizontal frequency of about 24 KHz. Also, in so-called high-definition televisions, the horizontal frequency is about 33.
75KHz is planned.

Currently, a multi-scanning television receiver has been proposed which allows a single device to receive various signals having different horizontal frequencies.

First, a multi-scan television receiver proposed by the applicant will be explained with reference to FIGS. 3 to 5.

Figure 3 shows the overall block diagram. In this figure, a typical television broadcast tuner or video tape recorder,
When receiving a normal video signal from a video disc player, satellite broadcast tuner, or some personal computers, the video signal supplied to the input terminal fil passes through the video process circuit (2) and the RGB process circuit (3). ) to form three primary color signals. In addition, the video/ROB switching signal supplied to the input terminal (4) is supplied to the ROB process circuit (3), whereby the three primary color signals from the selected video signal are output to the output circuit (5).
) is supplied to the cathode ray tube (6).

In addition, the video signal from the input terminal (1) is transferred to the sync separation circuit (
7), and the vertical and horizontal synchronization signals are separated.

Furthermore, the switching signal from the input terminal (4) is transmitted to the synchronous separation circuit (
7), whereby the vertical synchronizing signal from the selected video signal is supplied to the vertical deflection circuit (8), and the formed vertical deflection signal is applied to the vertical deflection yoke (9) of the negative 8iut tube (6). Supplied. Further, the horizontal synchronization signal from the video signal selected by the synchronization separation circuit (7) is supplied to the AFC circuit O1m and the mode detection circuit (11),
A signal from the FC circuit Ql is supplied to the horizontal oscillation circuit (12), and a normal control signal from the mode detection circuit (11) is supplied to the horizontal oscillation circuit (12). The signal from this horizontal oscillation circuit (12) is transmitted to the horizontal deflection circuit (
13) and the formed horizontal deflection signal is supplied to the horizontal deflection yoke (14) of the cathode ray tube (6). Furthermore, the signal from the horizontal deflection circuit (13) is supplied to a high voltage generation circuit (15) such as a flyback transformer, and the generated high voltage is supplied to the high voltage terminal (16) of the cathode ray tube (6). A portion is supplied to the AFC circuit (II).

Furthermore, the commercial power from the power input (17) is connected to the power supply circuit (1
8), and a normal voltage according to the signal from the mode detection circuit (11) is supplied to the horizontal deflection circuit (13). Also, commercial power from the power supply input (17) is supplied to another power supply circuit (19), and the voltage formed is supplied to other circuits.

This allows normal video signal reception. On the other hand, it receives digital or analog R, G, and B primary color signals (hereinafter referred to as RGB signals) from some personal computers, so-called captain demodulators, teletext demodulators, or scan converters. In this case, input terminal (20R) (20G) (2
The digital RGB signal supplied to 0B) and the analog RGB signal supplied to the input terminals (21R) (21G) (21B) are selected by the changeover switch (22) and supplied to the RGB process circuit (3). , input terminal (
4) and is supplied to the pressure circuit (5).

Further, the digital synchronization signal from the input terminal (20S) and the analog synchronization signal from the input terminal (21S) are selected by the changeover switch (23) and supplied to the synchronization separation circuit (7), and the input terminal (4) It is selected by a switching signal from , and is supplied to the vertical deflection circuit (8) and the AFC circuit 011. Furthermore, the signal from the synchronization separation circuit (7) is transmitted to the mode detection circuit (
11), a control signal corresponding to the number of horizontal synchronization signals is formed, and is supplied to a horizontal oscillation circuit (12), a horizontal deflection circuit (13), and a power supply circuit (18).

As a result, digital or analog RGB signals are received. Furthermore, when performing so-called superimposed image reception in which RGB signals are displayed superimposed on the above-mentioned normal video signal, the switching signal supplied to the input terminal (4) is set to RGB mode, and the input terminal ( 24)
Ys indicates the position of the signal to be superimposed and Ys indicates the range to be superimposed.
The m signal is supplied to the RGB process circuit (3), and switching between the video signal and the RGB signal is performed between these YsSYI11 signals.

Various signals are received in the manner described above.

Further, in the above-described apparatus, the horizontal deflection system is specifically configured as follows. In Fig. 4, the synchronization separation circuit (
The horizontal synchronization signal from 7) is sent to the horizontal synchronization signal input terminal (7H
) through which the mode detection circuit (11) is configured.
It is supplied to a voltage conversion circuit (FVC) (31) to form a voltage according to the horizontal frequency. The output voltage of this FVC (31) is applied to one fixed contact (32) of the changeover switch (32).
b), and the other fixed contact (32c) of this changeover switch (32) is grounded via a reference voltage source (33). In this case, the voltage value of this base f\lightning voltage (33) is equal to the voltage value obtained when, for example, a horizontal synchronizing signal of the NTSC system with a horizontal frequency of about 15.75 KHz is supplied to the input example of FVC (31). Set. In addition, this changeover switch (32) has an input terminal (4) as its control terminal.
A video/RGB switching signal from is supplied via the video RGB switching signal input terminal (4a), and the video/RGB switching signal from
When the B switching signal indicates video signal input, press the selector switch (
32), the movable contact (32a) is connected to the other fixed contact (32c).
), and when the video/RGB switching signal indicates ROB signal input, the movable contact (32) of the changeover switch (32)
a) is connected to one fixed contact (32b). The movable contact (32) of this changeover switch (32)
The voltage obtained at a) is passed through the Hasofa amplifier (34) to the voltage controlled oscillator (V
CO) (35).

The oscillation output of this VCO (35) is supplied through a drive circuit (36) to a switch notching transistor (37) constituting a horizontal deflection circuit (13).

Further, the voltage obtained at the movable contact (32a) of the changeover switch (32) is supplied through a gain control amplifier (38) to, for example, a YZ type parametric link power supply circuit (39) constituting the power supply circuit (18). The output voltage of this power supply circuit (39) is passed through the voltage divider circuit (40) to the gain control amplifier (
38) to stabilize the output voltage. This output voltage is supplied to the fly bank transformer (41).

A switching transistor (37) is connected in series to this flybank transformer (41). Further, a damper diode (42), a resonant capacitor (43), and a series circuit of a horizontal deflection yoke (14) and an S'f-correction capacitor (44) are connected in parallel to this switching transistor (37).

Further, the horizontal synchronizing signal is supplied to the detection circuit (45) constituting the AFC circuit α, and a signal from the voltage dividing circuit (46) provided in series with the switching transistor (37) is supplied to the detection circuit (45). AFC signal is formed. This signal is filtered by a low pass filter (LPF) (47
) is supplied to the control terminal of the VCO (35).

Furthermore, a switch circuit (
Capacitors (49) and (50) are connected through 48). In addition, the capacitor (52) (53) is connected in parallel to the figure 8 correction capacitor (44) through the switch circuit (51).
) are connected. In addition, the voltage from the FVC (31) is supplied to a comparator circuit (54) for binary comparison corresponding to voltages of 20 KHz and 30 KHz of the input horizontal frequency, for example.
0Ktl z or less, 20-30KHz, 30KH
A three-value comparison output corresponding to each range above z is formed,
Switch circuits (48) and (51)
Control is performed so that both of the two built-in switches are turned off or one of them is turned on.

As a result, in this horizontal deflection system, vCO (35
), an oscillation signal that varies from 15 to 34 KHz in synchronization with the input horizontal synchronizing signal is formed to perform horizontal deflection, and the power supply circuit (39) varies from 58 to 123 volts, for example, depending on the horizontal frequency. A voltage is generated to control the amplitude of the horizontal deflection to be constant. Also, the resonance capacitor (43) and the figure 8 correction capacitor (44)
) in parallel with the capacitor (4
9) (50) and (52) (53) are connected,
The characteristics of each are corrected.

Furthermore, in the above-mentioned apparatus, the four-sided deflection system is structured as follows. In Fig. 5, the synchronous separation circuit (7
) is input to the vertical synchronization signal input terminal (7s).
The electric current is supplied to a sawtooth wave oscillator (61) constituting the vertical deflection circuit (8) via the sawtooth wave oscillator (61), and a sawtooth wave is formed by, for example, charging and discharging a capacitor (62) with the current from a current source (63).

This sawtooth wave is supplied to a comparator circuit (64) to form a three-value comparison output indicating a predetermined voltage range and lower or higher voltage ranges.
) (65). This UDC (65
) is supplied with a vertical synchronization signal to the counting terminal. This UDC
The count value (65) is supplied to a DA conversion circuit (DAC) (66), and a current source (63) is controlled by the converted analog value.

Therefore, a sawtooth wave whose peak value (amplitude) is controlled within a predetermined voltage range is extracted from the sawtooth wave oscillator (61), regardless of the frequency of the vertical synchronization signal. This sawtooth wave is supplied to the vertical deflection yoke (9) through an output circuit (67).

Furthermore, a capacitor (68) is connected in series with this deflection yoke (9).
), a series circuit of a resistor (69) is connected, and a voltage dividing circuit (70) is connected in parallel to this resistor (69). The divided voltage output of this voltage dividing circuit (70) is supplied to an output circuit (67).

This ensures that vertical deflection always has a constant amplitude even if the vertical frequency changes. Furthermore, by making one of the resistors constituting the voltage dividing circuit (70) variable, the amplitude of the vertical deflection can be arbitrarily controlled.

Furthermore, another set of sawtooth wave oscillator (61) to DAC (66) circuits (oscillator (71) to DAC (76)) is provided, and the output value of the DAC (76) of this circuit forms a bin distortion correction signal. At the same time as being supplied to the circuit (77), for example, a parabolic signal with a vertical period from the connection midpoint between the deflection yoke (9) and the capacitor (68) is supplied to the forming circuit (77) to form a bin distortion correction signal. Ru. This signal is supplied to the pin distortion correction circuit.

In this way, in the above-mentioned mounting surface, the necessary horizontal and vertical deflections are performed according to various different horizontal and vertical frequencies, and various signals are received.

[Problem that the invention seeks to solve]

Conventionally, the power source for the voltage applied to the screen grid of the cathode ray tube (6) is obtained by rectifying the flybank pulse of the flybank transformer (41).

On the other hand, the beam current of the cathode ray tube (6) is inversely proportional to the cathode voltage as shown in FIG. 6, and as the screen grid voltage increases from EG2 to EG2', the cathode cutoff voltage increases. The above-mentioned multi-scan television receiver @! For example, when the horizontal frequency of the input signal is 1
Since the frequency changes significantly from 5kHz to 33kHz, the voltage applied to the screen grid also changes. For this reason, in a video signal having a relatively high horizontal frequency, there is an inconvenience in that black areas on the screen appear gray.

In view of these points, the present invention aims to propose a device in which the black part of the screen does not shine even if the horizontal frequency of the input signal changes.

[Means for solving problems]

The multi-scan television receiver of the present invention detects the horizontal frequency of an input signal, converts it into a voltage, applies this voltage to a horizontal deflection circuit, and switches the horizontal deflection frequency of this horizontal deflection circuit to receive input signals of different horizontal frequencies. In a multi-scan television receiver that receives images, the horizontal frequency of the input signal is detected, and the detected output is used to control the DC potential of the video signal that drives the cathode ray tube according to the horizontal frequency.

[Effect]

According to such a configuration, the DC potential of the video signal that drives the cathode ray tube is controlled according to changes in the horizontal frequency of the input signal, so that even if the horizontal frequency of the input signal changes, the black part of the screen will not illuminate. Story A.

〔Example〕

Hereinafter, an embodiment of the multi-scan television receiver of the present invention will be described with reference to FIG. This first
In the figure, parts corresponding to those in FIGS. 3 to 5 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

In FIG. 1, (80R), (80G) and (80B> are R from the RGB process circuit (3), respectively.
, G and B signals are supplied, and these input terminals (80R), (80G) and (80B>
resistors (81R), (81G) and (81
B) through the NPN type first . Second and third transistors (82R), (82G) and (82
B > bases respectively, and this first. 2nd and 3rd
Transistors (82R), (82G) and (
82B > emitters and ivy resistors (83R),
Commonly connected via (83G) and (83B),
This first. second and third transistors (82R),
The collectors of (82G) and (82B) are connected to resistors (84R), (84G) and (84B), respectively.
through the first ray tube (6) respectively. 2nd and 3rd Ka-)" are connected to KR, KG and KB, and this first
．． Second and third transistors (82R).

The collectors of (82G) and (82B) are connected to resistors (85R), (85G) and (85B), and coil (86R), respectively.

(86G) and (86B) are commonly connected through a series circuit. (87R), (87G) and (87B) are variable resistors for white balance adjustment, respectively, and these variable resistors (87R), (87G'')
and a power terminal (88R) to which power supply element B is supplied to one end of (87B).

(88G) and (88B), and ground the other ends of the variable resistors (87R), (87G) and (87B), respectively.
The sliders (87G) and (87B'') are connected to resistors (87G) and (87B''), respectively.
91? '), (89G') and (89B)
respectively through the first. The second and third transistors (82
R), (82G) and (82B) emitters and resistors (83R), (83G) and (83B)
) to the connection point. Also, (90G) and (9
0B) are variable resistors for white peak adjustment, and one ends of these variable resistors (90G) and (90B) are connected to the second and third transistors (82G) and (82G), respectively.
B) emitter and resistor (83G) and (83B)
and the other end of this variable resistor (90G) is connected in series between the power supply terminal (91G) to which power supply element B is supplied and the ground, resistors P5 (92G) and (93G).
) and the other end of the variable resistor (90B'') is connected in series between the power terminal (91B) to which power supply element B is supplied and the ground.
) connection point.

On the other hand, (41S) indicates the secondary coil of the fly bank transformer (41), and the first intermediate voltage tap of this secondary coil (41S) is connected to the anode of the diode (94). Connect the cathode of the resistor (95
) and a capacitor (96), and connect the connection point of this resistor (95) and capacitor (96) to the base of a PNP transistor (97), and the coils (86R) and (86G). and (86B)
The collector of this transistor (97) is grounded through a parallel circuit consisting of a resistor (98) and a capacitor (99).
) is connected to the common connection point of the resistors (83R), (83G) and (83B) via the buffer amplifier (100).

On the other hand, the secondary coil (4) of the flyback transformer (41)
1S ) second medium voltage tap with a diode (101
), and the cathode of this diode (101) is grounded through a series circuit consisting of a resistor (102) and a capacitor (103).
and the connection point of the capacitor (103) are connected to the anode of a diode (106) via a variable resistor (104) and a resistor (105) connected in series, and the cathode of this diode (106) is connected to a transistor (97). and connect the slider of the variable resistor (104) to the base of the cathode ray tube (
6) and the connection point of the variable resistor (104) and the resistor <105) is connected to the emitter of the transistor (97) via the resistor (107).

Other components such as a horizontal deflection system and a vertical deflection system are constructed in the same manner as in the multi-scan television receiver shown in FIGS. 3 to 5 described above.

According to this configuration, when a video signal with a horizontal frequency of about 33.75 kHz is input, the RGB process circuit (3
), the three primary color signals are input from the input terminal (80R), (80
G) and (80B), and these three primary color signals are supplied to the first .G) and (80B), respectively. Second and third transistors (82R).

(82G) and (82B) via cathode ray tube (6)
are supplied to the cathodes KR, KO and KB, respectively, and the horizontal frequency is set to approximately 1 by the flyback transformer (41).
The potential of the screen grid G2 of the cathode ray tube (6) increases compared to when the voltage is 5.75kllz. At this time, the voltage fluctuation of the screen grid G2 of the cathode ray tube (6) compared to when the horizontal frequency of the input signal is about 15.75k)lz is caused by the transistor (97), resistor (105),
(107) and a diode (106),
Transistor (97) via buffer amplifier (100)
), the first. The DC potential of the video signal supplied from the second and third transistors (82R), (82G) and (82B> to the cathodes KR, KO and KB of the cathode ray tube (6) is increased.For this reason, the screen grid Due to the rise in the potential of G2, the cathode ray tube (6
) Even if the cutoff voltage of the cathodes KR, KG, KB increases, the horizontal frequency will be lower than about 15.75kHz due to the increase in the DC potential of the video signal supplied to the cathodes KR, KG, KB. Relatively high approximately 33.75k
Even when a llz video signal is received, it is possible to prevent the black part on the screen from appearing gray.

Further, when a video signal with a horizontal frequency of 15.75 kHz is input, a predetermined image can be obtained as in the conventional case.

As described above (according to this example, the horizontal frequency of the input signal is detected and converted into a voltage, and this voltage is converted into a horizontal deflection circuit (13).
), the horizontal deflection frequency of the horizontal deflection circuit (13) is cut off to receive input signals of different horizontal frequencies. It is detected by the potential change of grid G2, and the cathode ray tube (
6) Since the direct current potential of the video signal that drives the video signal is controlled, there is an advantage that the black part of the screen can be prevented from shining even if the horizontal frequency of the input signal changes.

FIG. 2 shows another embodiment of the multi-scan television receiver of the present invention. In FIG. 2, parts corresponding to those in FIG.

In this example, the horizontal synchronization signal input terminal (7
11) Supply the horizontal synchronization signal obtained in
The output signal of this monostable multi-high break (31a) is supplied to a low pass filter (LPF) (31b''), and the smoothed output of this LPF (31b) is passed through a buffer amplifier (108) to a resistor (83R). .

It is supplied to the common connection point of (83G) and (83B).

In addition, the secondary coil (41) of the fly bank transformer (41)
Connect the second medium voltage tap of S) to the diode (101).
The cathode of this diode (101) is grounded through a series circuit consisting of a resistor (102) and a capacitor (103), and the connection point of this resistor (102) and capacitor (103) is variable. Resistor (104
) and connect the slider of this variable resistor (104) to the screen grid G2 of the cathode ray tube (6). Other components such as a horizontal deflection system, a vertical deflection system, and a signal processing system are constructed in the same manner as in the multi-scan television receiver shown in FIG. 1 described above.

Depending on the configuration, a voltage depending on the horizontal frequency of the input signal is applied to the monostable multivibrator (31a) and the LPF.
(31b), and this output voltage causes the first. Second and third transistors (82R), (82G
) and (82B) to cathode KR of cathode ray tube (6)
, KG, and KB, and the horizontal frequency is relatively high compared to about 15.75 kllz, about 33,7
Even when a 5 kHz video signal is received, black areas on the screen can be prevented from appearing gray.

As described above, the horizontal frequency of the input signal is detected and converted into a voltage, this voltage is applied to the horizontal deflection circuit (13), and the horizontal deflection frequency of this horizontal deflection circuit (13) is switched to generate an input signal of a different horizontal frequency. In a multi-scan television receiver that receives images, the horizontal frequency of the input signal is detected, and this detection output is used to control the cathode ray tube (
6), it is easy to understand that since the DC potential of the video signal driving the video signal is controlled, it is possible to obtain the same effect as the embodiment shown in FIG. 1 in this embodiment as well.

It goes without saying that the present invention is not limited to the above-described embodiments, and can take various other configurations without departing from the gist of the present invention.

〔Effect of the invention〕

According to the present invention, in response to changes in the horizontal frequency of the input signal,
The direct current potential of the video signal that drives the ζ cathode ray tube (6) is controlled, and there is the advantage that the black part of the screen can be prevented from shining even if the horizontal frequency of the input signal changes.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the essential parts of the multi-scan television receiver of the present invention, FIG. 2 is a block diagram showing another embodiment of the multi-scan television receiver of the present invention, and FIG. Fig. 4 is a block diagram showing an example of a John receiver, Fig. 4 is a block diagram showing the horizontal deflection system extracted from Fig. 3, Fig. 5 is a block diagram showing the vertical deflection system extracted from Fig. 3, and Fig. 6 is a block diagram showing the vertical deflection system extracted from Fig. 4 is a diagram for explaining FIG. 3. FIG. (6) is Yin J full line tube, (31) is FVC, (31a) is medium stable multi-high break, (31b) HaL P
F, (41) is the flyback transformer, (415) is the secondary coil of the flyback transformer, (80R). (80G) and (80B) are input terminals, (82
1? ). (82G > and (82B') are the first, second and third transistors, respectively, (94), (101) and (106) are diodes, (95) and (98
), (102). (105) and (10'7) are resistors, (96)
. (99) and (103) are capacitors, (97) is a transistor, (100) and (108) are buffer amplifiers, respectively, KR, KG, and KB are cathodes, and G2 is a screen grid.

Claims (1)

[Claims] 1. Detecting the horizontal frequency of an input signal, converting it into a voltage, applying the voltage to a horizontal deflection circuit, and switching the horizontal frequency of the horizontal deflection circuit to receive input signals of different horizontal frequencies. In the multi-scan television receiver, the horizontal frequency of the input signal is detected, and the detected output controls the DC potential of the video signal that drives the cathode ray tube according to the horizontal frequency. A multi-scan television receiver. 2. The horizontal frequency of the input signal is detected by a potential change of a screen grid of the cathode ray tube, and the detected output is used to control the DC potential of the video signal that drives the cathode ray tube. 2. The multi-scan television receiver according to claim 1.