KR0116286Y1 - Electronic switch circuit in high frequency modulator - Google Patents

Abstract

The present invention relates to a high frequency modulator used in a video signal processing device such as a VCR or a satellite broadcasting receiver, and more particularly, to an electronic switch circuit of a high frequency modulator that simplifies a circuit by reducing the number of transistors that are broadcast signal suppression elements.

The electronic switch circuit of the high frequency modulator of the present invention for providing the same, the high pass filter unit for filtering only the signal of the high frequency region of the TV broadcast signal coming through the antenna, and the high frequency signal filtered through the high pass filter unit appropriately distribute A signal distribution unit for distributing the signal to a TV tuner and a VCR tuner, a band pass filter unit for passing only a frequency signal of a predetermined band among TV broadcast signals distributed from the signal distribution unit and transmitted to the TV tuner, and the signal when viewing the VCR. An antenna input signal switching unit for blocking the TV video signal from the distribution unit from being applied to the TV tuner, and selectively switching the TV broadcast signal and the VCR modulated signal from the bandpass filter unit according to TV viewing or VCR viewing It includes a high frequency modulated signal switching unit for outputting to the TV tuner In the high-frequency modulator, the high-frequency modulated signal switching unit, the supply voltage and the VCR modulation signal is applied to the anode terminal in common, and the output terminal of the band pass filter unit and the input terminal of the TV tuner in common to the cathode terminal And a band pass filter unit comprising: a first capacitor connected between a cathode terminal of the diode and a first node; a second capacitor connected between the first node and a second node; A third capacitor connected between a second node and one output terminal of the signal distribution unit, a first inductor connected between the first node and a ground voltage, a second inductor connected between the second node and a ground voltage; And a third inductor connected between the cathode terminal and the ground voltage, wherein the antenna input signal switching unit includes a resistor connected to a supply voltage input terminal side. A first NPN type bipolar transistor having the first node connected to the collector, a ground voltage applied to the emitter, and the resistor connected to the base, a fourth inductor connected between the resistor and the third node; One terminal of the fourth inductor is connected to the base, and the second node is configured as a second NPN type bipolar transistor connected to the collector and the ground voltage is applied to the emitter.

Description

Electronic switch circuit of high frequency modulator

The present invention relates to an electronic switch circuit of a high frequency modulator used in a video signal processing device such as a VCR or a satellite broadcasting receiver, and more particularly, to an electronic switch circuit of a high frequency modulator that simplifies the circuit by reducing the number of transistors that are broadcast signal suppression elements. will be.

In general, when using a VCR connected to a satellite broadcasting device (e.g. TV), when watching a TV broadcast signal, the VCR playback signal input from the VCR is suppressed from being input to the TV. You should suppress the signal from being input to the TV. The circuit for separating the TV broadcast signal and the VCR playback signal or suppressing unnecessary signals is generally controlled by an electronic position circuit built in a high frequency modulator.

As shown in FIG. 1, the electronic switch circuit of the conventional high frequency modulator includes a high pass filter unit 10 for filtering only a signal of a high frequency region among TV broadcast signals coming through the antenna input terminal I, and the high pass filter unit ( A signal distributor 20 for appropriately distributing the filtered high frequency signal through the first antenna output terminal 2 on the TV tuner side and the second antenna output terminal 3 on the VCR tuner side; Three band pass filter 30 which passes only the frequency signal of a predetermined band among the TV broadcast signals distributed by the signal distributor 20 and transmitted to the TV tuner 2 side, and from the band pass filter 30 And a high frequency modulated signal switching unit 41 for selectively outputting the TV broadcast signal of the VCR and the modulated signal 4 modulated from the high frequency modulator of the VCR according to TV viewing or VCR recording, and the high frequency modulated signal of the VCR. Inn on the device side The antenna input signal switching unit 42 is configured to block the TV broadcast signal from the visible antenna input terminal 1 from being applied to the TV tuner side 2 through the band pass filter unit 30.

FIG. 2 is a detailed circuit diagram of the conventional electronic switch circuit portion 40 shown in FIG.

As shown in the drawing, a high band pass filter unit 10 for passing only a signal of a high frequency band among TV broadcast signals input from the antenna, and a TV broadcast signal filtered through the high band pass filter unit 10 may include a first antenna ( And a signal distribution unit 20 distributed to the TV tuner side output through 2) and the VCR tuner side output through the second antenna 3. The high frequency modulated signal switching unit 41 selectively outputs a VCR modulated signal and a TV video signal to the TV tuner when the TV is viewed or when the VCR is viewed, and the signal distributor 20 when the VCR is viewed. An antenna input signal switching unit 42 for suppressing a TV video signal output from the high frequency modulated signal switching unit 41 and a TV video signal output from the signal distribution unit 20 by band-passing the The band pass filter unit 30 outputs the high frequency modulated signal switching unit 41.

The high frequency modulated signal switching section 41 includes a resistor R1 connected to the supply voltage B + side, a capacitor C1 connected to the VCR modulation signal input terminal side, and one terminal of the capacitor C1. The collector is connected, the one terminal side of the resistor R1 is connected to the base, and the emitter is composed of an NPN type bipolar transistor Q1 connected to the first antenna output terminal 2 side (TV tuner).

The bandpass filter unit 30 includes four capacitors C2 to C5 connected in series between the output terminal of the signal distribution unit 20 and the emitter terminal of the NPN type bipolar transistor Q1. Inductors L1 to L3 connected between a node (node between C2 and C3, a node between C3 and C4, a node between C4 and C5) and a ground voltage Vss connected between capacitors, and the NPN type bipolar transistor It consists of an inductor L4 connected between the emitter terminal of Q1 and the battery voltage Vss.

In addition, the antenna input signal switching unit 42 has the supply voltage B + applied to the base, and each collector is a node between the inductors (node between C2 and C3, node between C3 and C4, C4 and C5). Internode) and NPN-type bipolar transistors Q2 to Q5, each emitter connected to a ground voltage Vss, the supply voltage B + and the NPN-type bipolar transistors Q2 to Q5. It consists of resistors R2 to R4 connected between the base terminals of < RTI ID = 0.0 >

In addition, the high pass filter 10 includes an inductor L5 connected between the antenna input signal 1 input terminal and a ground voltage Vss, the antenna input signal 1 input terminal, and the signal distribution unit. It consists of a capacitor C7 connected between the output terminals output to (20).

In addition, the signal distributor 20 is connected to the inductor T2 connected between the input terminal from the high pass filter unit 10 and the ground voltage Vss and the high pass filter unit 10. It consists of a resistor R5 and an inductor T1 connected in parallel between the input terminal and the second antenna output terminal 3 (VCR tuner).

The operation of the electronic switch circuit of the conventional high frequency modulator by the above configuration can be largely classified into two types.

First, the operating voltage B + shown in FIG. 2 is not applied even when watching TV broadcast through the second antenna 3 or when recording a TV fireproof signal to the VCR. Therefore, the VCR signal modulated by the high frequency modulator cannot be output to the TV tuner 2 so that the transistor Q1 cannot operate, and at the same time, the broadcast signal received at the antenna input terminal 1 is transmitted through the high pass filter unit 10. Only the desired frequency band is divided in two by the transformers T1 and T2 of the signal distributor 20, one of which is output to the VCR tuner 3 and applied to the VCR, and the other signal is a three-stage band. It is output to the TV tuner 2 side through the pass filter unit 30 so as to be applied to the TV.

On the other hand, when viewing the VCR playback screen, the operating voltage B + is applied to the high frequency modulated signal switching unit 41 and the antenna input signal switching unit 42 to operate the transistor Q1 of the high frequency modulated signal switching unit 41. Since it is in the state, the VCR signal modulated by the high frequency modulator is output to the TV tuner 2 side through the collector and emitter terminals of the transistor Q1 and applied to the TV. At this time, the TV video signal input from the antenna input terminal (1) is all emitted to the ground voltage through the transistors (Q2 Q4) of the antenna input signal switching unit 42 to suppress the unnecessary broadcast signal to the maximum (typically 60 70dB).

In this way, by selectively switching the operating power according to TV viewing or VCR viewing, mutual interference between the TV video signal and the VCR modulated signal input to the antenna can be suppressed.

However, in the electronic switch circuit of the conventional high frequency modulator configured as described above, the transistors of the three stages configured to attenuate the power of the TV broadcast signal when viewing the VCR playback screen, and the protection resistors connected to the bass terminal to protect these transistors, etc. By providing a large number of parts, the circuit is complicated, and there is a problem that inhibits the miniaturization of the device.

Accordingly, the present invention has been made to solve the above problems, and an object of the present invention is to provide an electronic switch circuit of a high frequency modulator that simplifies the circuit by reducing the demand of a transistor, which is a broadcast signal suppression element.

1 is a block diagram of a high frequency modulator according to the prior art

2 is a detailed circuit diagram of the electronic switch circuit portion shown in FIG.

3 is an electronic switch circuit diagram of a high frequency modulator according to an embodiment of the present invention

＊ Explanation of symbols on main parts of drawing

1: antenna input terminal 2: first antenna output terminal (TV tuner)

3: second antenna output terminal (VCR tuner) 4: high frequency modulated signal

10: high pass filter 20: signal distribution

30,31: Band pass filter part 40,50: Electronic switch circuit part

41,51: high frequency modulation signal switching unit 42,52: antenna input signal switching unit

In order to achieve the above object, the electrical switch circuit of the high frequency modulator according to the present invention is a high pass filter for filtering only the signal of the high frequency region of the TV broadcast signal coming through the antenna, the high frequency signal filtered through the high pass filter A signal distribution unit for properly distributing a signal to a TV tuner and a VCR tuner, a band pass filter unit for passing only a frequency signal of a predetermined band among the TV broadcast signals distributed from the signal distribution unit and transmitted to the TV tuner side, and the VCR An antenna input signal switching unit for blocking the TV video signal from the signal distribution unit from being applied to the TV tuner, the TV broadcast signal from the band pass filter unit, and the VCR modulation signal for TV viewing or VCR viewing. Therefore, the high frequency modulated signal switching selectively outputting to the TV tuner In the high frequency modulator comprising a, the high frequency modulated signal switching unit, the supply voltage and the VCR modulated signal is commonly applied to the anode terminal and the output terminal of the band pass filter unit and the input terminal of the TV tuner in common to the cathode terminal And a band pass filter unit comprising: a first capacitor connected between the cathode node and the first node of the diode; a second capacitor connected between the first node and the second node; A third capacitor connected between a second node and one output terminal of the signal distribution unit, a first inductor connected between the first node and a ground voltage, and a second inductor connected between the second node and a ground voltage And a third inductor connected between the cathode terminal and the ground voltage, wherein the antenna input signal switching unit has a supply voltage input terminal side. A first NPN type bipolar transistor having a resistor connected to the first node connected to the collector, a ground voltage applied to the emitter, and the resistor connected to the base; and a fourth connected between the resistor and the third node. And a second NPN type bipolar transistor in which an inductor and one terminal of the fourth inductor are connected to a base, the second node is connected to a collector, and a ground voltage is applied to the emitter.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

3 is an electronic switch circuit diagram of a high frequency modulator according to an embodiment of the present invention, and a band pass filter unit configured to pass only a frequency signal of a predetermined band among TV broadcast signals distributed by the signal distribution unit 20 and transmitted to the TV tuner side. (31), an antenna input signal switching unit (52) for preventing the TV video signal from the signal distribution unit (20) from being applied to the TV tuner when the VCR is viewed, and the band pass filter unit (31). Unlike the electronic switch circuit of the conventional high frequency modulator, the configuration of the high frequency modulated signal switching unit 51 which selectively switches the TV broadcast signal and the VCR modulated signal according to TV viewing or VCR viewing and outputs it to the TV tuner It is implemented.

The high frequency modulated signal switching unit 51 is an anode terminal and the supply voltage and the VCR modulation signal are applied in common, and the output terminal of the band pass filter unit 31 and the input terminal of the TV tuner are common to the cathode terminal. It consists of a diode connected with.

The band pass filter 31 may include a first capacitor C2 connected between the cathode terminal of the diode and the first node, and a second capacitor connected between the first node and the second node ( C3), a third capacitor C4 connected between the second node and one output terminal of the signal distribution unit, a first inductor L1 connected between the first node and the ground voltage, and the second And a second inductor L2 connected between the node and the battery voltage, and a third inductor L4 connected between the cathode terminal and the ground voltage.

In addition, the antenna input signal switching unit 52 includes a resistor R2 connected to a supply voltage input terminal side, a first node connected to a collector, a ground voltage applied to the emitter, and the resistor R2. ) Is connected to the base of the first NPN-type bipolar transistor (Q2), the fourth inductor (LX) connected between the resistor (R2) and the third node, and one terminal of the fourth inductor (LX) And a second NPN type bipolar transistor Q3 connected to the collector and to which the second node is connected to the collector and to which the ground voltage is applied to the emitter.

The operation by the above configuration will be described.

First, since the operating voltage B + is not applied during VCR recording or watching TV broadcasts, two transistors Q2 Q3 of the diode D1 of the high frequency modulated signal switching unit 51 and the antenna input signal switching unit 52. The high frequency modulated signal cannot be output to the first antenna output terminal 2, and the TV broadcast signal received at the antenna input terminal 1 is a high pass filter composed of an inductor L5 and a capacitor C6. It is applied to the signal distribution unit 20 via the unit 10, and is divided by two transformers T1 and T2 of the signal distribution unit, and a signal is applied in the same manner as in the prior art.

When the VCR playback screen is viewed, the operating voltage B + is applied to the diode D1 of the high frequency modulated signal switching unit 51 and the two transistors Q2 and Q3 of the antenna input signal switching unit 52 are turned on. Therefore, the high frequency modulated signal is output to the first antenna output terminal 2 and applied to the TV tuner.

At this time, the TV broadcast signal received by the antenna input terminal 1 and uniformly distributed by the signal distribution unit 20 flows to the ground through the collector-emitter terminals of the two transistors Q2 and Q3 to output the first antenna. It is not output to the terminal 2, and because the signal blocking inductor Lx is formed at the base terminals of the transistors Q2 and Q3, the remaining forces are reflected and attenuated by the transistors Q2 and Q3 through the inductor Lx, which is unnecessary. The radiation is suppressed as much as possible, and the inductance value of the inductor Lx is adjusted to an appropriate value so that the broadcast signal can be attenuated again.

As described above, according to the electronic switch circuit of the high frequency modulator of the VCR and the satellite broadcasting receiver according to the present invention, the transistor suppression circuit consisting of three stages is reduced to two stages in order to minimize the inflow of the broadcast signal when watching VCR. By doing so, there is an excellent effect of reducing the number of parts, facilitating manufacture, and miniaturizing the device.

In addition, preferred embodiments of the present invention are disclosed for the purpose of illustration, those skilled in the art will be able to various modifications, changes, additions, etc. within the spirit and scope of the present invention, such modifications and modifications belong to the following utility model registration claims Should be seen.

Claims (1)

A high pass filter unit 10 for filtering only signals in the high frequency region of the TV broadcast signals received through the antenna, and a signal for distributing the high frequency signals filtered through the high pass filter unit to the TV tuner and the VCR tuner. A distribution unit 20, a bandpass filter unit 31 for passing only a frequency signal of a predetermined band among TV broadcast signals distributed from the signal distribution unit and transmitted to the TV tuner, and the signal distribution unit 20 when the VCR is viewed; An antenna input signal switching unit 52 for blocking the TV video signal from the TV tuner from being applied to the TV tuner, and selectively selecting the TV broadcast signal from the band pass filter unit and the VCR modulation signal according to TV viewing or VCR viewing In the high frequency modulator comprising a high frequency modulated signal switching unit 51 for switching to the output to the TV tuner, the high frequency modulated signal switch The diode 51 is a diode in which the supply voltage and the VCR modulation signal are commonly applied to an anode terminal, and an output terminal of the band pass filter unit 31 and an input terminal of the TV tuner are commonly connected to a cathode terminal. The band pass filter 31 includes a first capacitor C2 connected between the cathode terminal of the diode and a first node, and a second connected between the first node and the second node. A capacitor C3, a third capacitor C4 connected between the second node and one output terminal of the signal distribution unit, a first inductor L1 connected between the first node and the ground voltage, and And a second inductor L2 connected between a second node and a ground voltage, and a third inductor L4 connected between the cathode terminal and a ground voltage. The antenna input signal switching unit 52 includes: A resistor R2 connected to a supply voltage input terminal side and the first node; Is connected to the collector, a ground voltage is applied to the emitter, and the fourth inductor is connected between the first NPN type bipolar transistor Q2 having the resistor R2 connected to the base, and the resistor R2 and the third node. LX and a second NPN type bipolar transistor Q3 having one terminal of the fourth inductor LX connected to the base, the second node connected to the collector, and a ground voltage applied to the emitter. Electronic switch circuit of high frequency modulator.