JPH0918807A - Television receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means preventing a signal processing part drastically reducing load current for a vertical blanking period from becoming the fluctuation factor of power source voltage to other signal processings without strengthening the smoothing filter of a power source line, in particular, and imparting no hindrance to the output of video to a screen or the output of a signal to an external equipment. SOLUTION: In a signal processing part 11 in which load current is reduced for a vertical blanking period, the control signal 15 showing the period is outputted, and the switching device 13 operating according to the control signal 15 and dummy load 14 are used. The dummy current corresponding to the load current amount reducing for the period is made to flow in the vicinity of the signal processing part 11 and the fluctuation of power source voltage is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver for simultaneously processing a plurality of television signals having different synchronization timings.

[0002]

2. Description of the Related Art In recent years, a television receiver is not limited to simply receiving one terrestrial broadcast and outputting its video and audio, but also receiving another terrestrial broadcast or satellite broadcast, or an external broadcast. By receiving the television signal input from the device, processing them simultaneously, and switching the signals appropriately, it is possible to output multiple images simultaneously on one screen, or to separate the signals output on the screen. Advanced functions such as outputting television signals for external devices are being advanced.

Conventionally, in this type of television receiver, careful design is performed so as not to cause a problem that signals are cross-talked between a plurality of television signals which are simultaneously processed. Has been done. In addition, there are various problems that appear as interference because the frequency and timing of the synchronization signal differ between these signals.

FIG. 3 shows a configuration of power supply to two types of signal processing units for processing different television signals in a conventional television receiver. The configuration will be described below with reference to the drawings. explain.

In FIG. 3, reference numeral 1 is a power source output section for outputting a DC voltage Vs, and 2 is a common impedance Zs which means an impedance of the power source and an impedance due to a common transmission line. A signal processing unit a 5 processes the input signal a of 6 and outputs the output signal a of 7. Reference numeral 8 is a signal processing unit b, which processes 9 input signals b having a synchronization timing different from 6 and outputs 10 output signals b. Reference numerals 3 and 4 respectively denote impedances Za and Zb due to the transmission path to the signal processing unit a of 5 and the signal processing unit b of 8 after the common impedance Zs of 2. Further, although not shown in the drawing, the ground of the power output unit 1, the ground of the signal processing unit a of 5, and the ground of the signal processing unit b of 8 are connected to each other through a certain impedance.

As shown in the figure, in a television receiver, a common power supply output section often supplies a power supply voltage to various signal processing sections. The power supply output unit 1 operates so as to stably output the DC voltage Vs, but due to the common impedance Zs of 2 and the like, the common power supply voltage Vo fluctuates due to an increase or decrease in the load current. In the signal processing unit a of 5, which is supplied with power through the common impedance Zs of the power output units 1 to 2 and the impedance Za of the transmission line of 3, not only the input voltage Va varies according to the load current Ia, but also 8 Since the power supply voltage Vo fluctuates in accordance with the load current Ib of the signal processing unit b, the input voltage Va of the signal processing unit a of 5 is affected, and the output signal a of 7 There is concern about interference by the signal processing unit b of 8.

In order to suppress the fluctuation of the power supply voltage, it is important to reduce the impedance due to the transmission lines 2 and 3 and 4, and further, when the fluctuating frequency is about the horizontal synchronizing frequency of the television signal or more. In addition, the effect of strengthening the smoothing filter such as a capacitor in the power supply line is great, and it is desired that the signal processing unit itself is resistant to power supply voltage fluctuation.

On the other hand, one of the television signals is a high-definition signal having a large amount of information, which is driven by a low voltage as typified by a signal processing circuit which receives and decodes the MUSE signal which is the compressed transmission signal. However, the television receiver also has a signal processing circuit that has a significantly larger load current than other signal processing units and that the load current tends to greatly decrease during the vertical blanking period. It has to be built.

[0009]

However, in the above-mentioned conventional television receiver, one of the signal processing units for simultaneously processing a plurality of television signals having different synchronization timings has a large load current during the vertical blanking period. When a signal processing circuit that has a tendency to decrease is provided, fluctuations in the load current due to the internal impedance of the power supply, the impedance due to the transmission path, and the impedance between the ground, etc. It becomes a fluctuation factor, and the fluctuation is a very slow fluctuation of the vertical blanking period of about 60 Hz, so it is difficult to sufficiently remove the fluctuation ripple voltage even if the smoothing filter of the power supply line is considerably strengthened. This may affect the signal processing unit and interfere with the video output to the screen or the signal output to external devices. We had a problem that appeared me.

The present invention solves the above-mentioned conventional problems, and a signal processing unit having a tendency that the load current largely fluctuates during the vertical blanking period becomes a factor of fluctuation of the input voltage to other signal processing units. It is an object of the present invention to provide a television receiver that does not interfere with the video output to the screen or the signal output to an external device by preventing the power supply line smoothing filter from being specially strengthened. .

[0011]

In order to achieve this object, the television receiver of the present invention reduces the load current in a signal processing section which tends to greatly decrease the load current during the vertical blanking period. A switching circuit that outputs a pulse control signal indicating a period and operates according to the pulse control signal is provided, and a current equivalent to the load current amount that decreases in the above period by using a dummy load is used as a dummy current in the vicinity of the signal processing unit. The method of flowing in is used.

[0012]

With this means, the smoothing filter of the power supply line is specially designed so that the signal processing section having a tendency that the load current greatly decreases during the vertical blanking period becomes a factor of fluctuation of the input voltage to the other signal processing section. It is possible to realize a television receiver that is prevented without strengthening and does not interfere with image output to a screen or signal output to an external device.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of power supply to two types of signal processing units for processing different television signals in the television receiver according to this embodiment.

In FIG. 1, 1 to 7 and 9 and 10 have the same structure as the power supply in the conventional television receiver shown in FIG. It is assumed that the signal processing unit b which processes the signal b and outputs the output signal b of 10 has a tendency that the load current Ib greatly decreases in the vertical blanking period synchronized with the input signal b of 9. Reference numeral 12 denotes a dummy current switching unit, which is arranged in the immediate vicinity of the signal processing unit b of 11, and is a dummy current control signal (vertical blanking synchronization signal) 15 representing a period during which the load current Ib greatly decreases (from the signal processing unit b of 11). Output) and is composed of the dummy loads Zc of the switches 13 and 14.

The operation of supplying power to the television receiver configured as described above will be described.

The load current Ib of the signal processing section b of 11 is 9
It decreases during the vertical blanking period synchronized with the input signal b. The dummy current switching unit 12 operates the switch 13 by the dummy current control signal (vertical blanking synchronization signal) 15 input from the signal processing unit b of 11, and the dummy load Zc of 14 reduces the load current Ib. At the timing, a current corresponding to the reduced amount is passed as the dummy current Ic.

FIG. 2A shows an example of the waveforms of the load current and the power supply voltage according to the conventional configuration (FIG. 3), and FIG. 2B shows the load current, the dummy current and the configuration according to the present embodiment (FIG. 1). It is an example of a waveform of the power supply voltage.

As shown in the figure, conventionally, as the load current Ib of the signal processing unit b of 8 decreases, the power supply voltage Vo fluctuates under the influence of the common impedance Zs of 2, and as a result, 5 Although the input voltage Va of the signal processing unit a fluctuates, according to the configuration of the present embodiment, the dummy current Ic is caused to flow in synchronization with the decrease of the load current Ib of the signal processing unit b of 11, so that the power supply voltage is reduced. It is possible to prevent the fluctuation of Vo and eventually the input voltage Va.

[0020]

As described above, according to the present invention, in a television receiver for simultaneously processing a plurality of television signals having different synchronization timings, a signal having a tendency that the load current greatly decreases during the vertical blanking period. The processing section is provided with a switching circuit that outputs a pulse control signal indicating a period during which the load current decreases, and a switching circuit that operates according to the pulse control signal is provided. Is used as a dummy current in the vicinity of the same signal processing unit to prevent fluctuations in the input voltage to other signal processing units without specially strengthening the smoothing filter of the power supply line, It is possible to realize a television receiver that does not interfere with the video output of the above or the signal output to the external device.

[Brief description of the drawings]

FIG. 1 is a block diagram of a power supply circuit according to an embodiment of the present invention.

2A is a waveform diagram of a load current and a power supply voltage by a conventional power supply circuit, and FIG. 2B is a waveform diagram of a load current, a dummy current, and a power supply voltage by the power supply circuit in one embodiment of the present invention.

FIG. 3 is a block diagram of a conventional power supply circuit.

[Explanation of symbols]

1 Power Output Unit 2 Common Impedance Zs 3 Impedance Za 4 Impedance Zb 5 Signal Processing Unit a 6 Input Signal a 7 Output Signal a 9 Input Signal b 10 Output Signal b 11 Signal Processing Unit b 12 Dummy Current Switching Unit 13 Switcher 14 Dummy Load Zc 15 Dummy current control signal (vertical blanking synchronization signal)

Claims (1)

[Claims] 1. A television receiver comprising a plurality of signal processing units for simultaneously processing a plurality of television signals, wherein the signal processing unit reduces the load current during a vertical blanking period of an input signal, A dummy current control signal that outputs a dummy current control signal is provided, and a dummy current switching unit that includes a switch and a dummy load that operates according to the control signal is provided, and a dummy current that corresponds to the load current that decreases during the above period is provided in the dummy current switching unit. A television receiver characterized in that the signal is sent in the vicinity of the signal processing section.