KR20050016717A - Television receiver with isolated inputs - Google Patents

Abstract

Two first switches 21, 22, which are activated in a first mode and are located in parallel to the television input 11, comprising a television and radio inputs 11, 12 for receiving television and radio signals, in a second mode A receiver comprising two second switches 23, 24 activated and anti-serially positioned at the radio input 12, and a control circuit 3 controlling this switching circuit 2; 1) is modified in such a way that a strong radio signal can no longer disturb the television signal. In this way, one of the first switches 21 and one of the second switches 23 together isolate the inputs 11, 12 from each other, and the control circuit 3 sends the first control signal to the first switch 21. , 22) and a second control signal to the non-common point of the semi-serial second switches 23, 24. This type of receiver 1 no longer needs different switching circuits 2 with respect to the shielded and unshielded radio inputs. The switches 21, 22, 23, 24 are diodes, and the control circuit 3 comprises transistors 31, 32 for controlling such diodes.

Description

Television receiver with isolated inputs {TELEVISION RECEIVER WITH ISOLATED INPUTS}

The present invention provides a first input for receiving a first signal, a second input for receiving a second signal, at least two first switches to be activated in a first mode, and at least two second switches to be activated in a second mode. It relates to a receiver including a switching circuit provided and a control circuit for controlling the switching circuit.

The invention also provides a switching circuit and control circuit for use in such a receiver, a television comprising such a receiver, a first input for receiving a first signal and a second input for receiving a second signal, in a first mode. Activating at least two first switches, activating at least two second switches in a second mode, and controlling the switching.

Such a receiver has, for example, a satellite disk antenna or a first (shielded) input to be coupled to a cable or television antenna, for example for receiving a first signal such as a television signal, for example a frequency modulated radio. Input a second (if shielded or unshielded) input to be coupled to a radio antenna (e.g. when shielded) or a wire (e.g. unshielded) to receive a second signal such as a signal or FM radio signal. Branch is a television receiver. In general, the first switch is located in parallel with the first input, is activated (becomes conductive) in the first (television) mode, and the second switch is anti-serially located at the second input, Activated (eg becomes conductive) in the second (radio) mode.

Prior art receivers are known from US Pat. No. 6,020,936, and in FIG. 2 of this publication, D1 and D3 are conductive in TV mode, D2 and D4 are nonconductive, and D2 and D4 are conductive in FM mode, and D1 and D3. Discloses TVIN (first input) and FMIN (second input) coupled to each other via four non-conductive diodes D1 to D4 (switches). This conductivity and non-conductivity are controlled by control circuits that produce TV / FM signals (control signals). In terms of TVIN, D1 and D3 are located in parallel, and in terms of FMIN, D2 and D4 are located in anti-serial.

Known receivers are particularly disadvantageous due to the strong second signal (strong FM signal) reaching through the second input FMIN which disturbs the first signal (TV signal).

1 is a block diagram forming an embodiment of a receiver according to the invention, comprising a switching circuit according to the invention and a control circuit according to the invention.

It is an object of the present invention to provide a receiver as defined in the preamble, in which disturbance of any first signal by a particularly strong second signal is reduced. The invention is defined by the independent claims. The dependent claims define advantageous embodiments.

By isolating the inputs from each other via at least two switches, compared to prior art US Pat. No. 6,020,936, where there is a coupling through only one switch D1 (by adding one or more other elements) between the inputs, The inputs at the receiver according to the invention are much better isolated from each other. Even a strong second signal can no longer disturb any first signal. Due to this good isolation, the first switch and the second switch now require a (separate) first control signal and a second control signal. When supplying the second control signal to the (semi-serial) second switch (non-common point), one of the first switches can be advantageously coupled to the common point of these (semi-serial) second switches.

The present invention is based in particular on the insight that more switches in the combination lead to more isolation, and in particular one of the first switches is a semi-serial second switch in which the non-common point is coupled to the second input (prior art Is based on the basic idea that they should be moved from the non-common point to the common point (of the invention) of these semi-serial second switches.

The present invention solves the problem of providing a receiver which better isolates the inputs, which are particularly well defined from one another, in particular the switching of which no longer differs for a shielded second input and a second unshielded input. It is advantageous in that it does not require a circuit.

A first embodiment of a receiver according to the invention as defined in claim 2 is a diode in which the first switch is a diode whose anode is coupled to the first input via one or more elements, and the second switch forms a cathode in common. It is advantageous in that it is a diode. By supplying the first control signal to the anode of the first switch and the second control signal to the anode of the second switch, the inverter of the prior art can be avoided. Diodes are advantageous in that they are low cost switches.

As defined in claim 3, a second embodiment of the receiver according to the invention is characterized in that the cathode of one of the first switches is coupled to a common point, and the cathode of the first switch is connected to the filter- via one or more elements. Coupled to the input, the anode of one of the second switches is coupled to the second input through one or more elements, and the other anode of the second switch is coupled to the filter input through one or more elements. Elements include capacitors, inductors, resistors and the like, for example for filtering purposes.

A third embodiment of a receiver according to the invention as described in claim 4 comprises a low pass filter comprising filter inputs for a low pass filtering television signal and a radio signal. The low pass filter is then used for both kinds of signals, which is advantageous. There are often more filters, such as mid-band filters and high-pass filters, which are often coupled to the first input through one or more elements for mid-band filtering and high-pass filtering television signals.

In a fourth embodiment of the receiver according to the invention as described in claim 5, it is advantageous that the control circuit comprises a third switch, the first contact of which is in common with the first series circuit of the two resistors. Coupled to the non-common point of the two resistors is coupled to the anode of the first switch, the control circuit having a first contact coupled to a common point of the second contact of the first transistor and the second series circuit of the two resistors. And a fourth switch, wherein the non-common point of these two resistors is coupled to the anode of the second switch, and the common point of the second switches is grounded through the resistor. This control circuit is advantageous in that it is inexpensive and less complicated. The resistance between common point and ground allows both second switches to be reversely switchable biased with respect to improved nonconductivity.

In a fifth embodiment of a receiver according to the invention as described in claim 6, it is advantageous that the third switch comprises a first transistor and the fourth switch comprises a second transistor, wherein the first contact of the transistor is Collector, the second contact of the transistor is a base, the emitter of the transistor is grounded, each collector is coupled to a first voltage source through at least one resistor, and the base of the first transistor is a second transistor through one resistor Is coupled to the collector of the second transistor, and the base of the second transistor is coupled to the second voltage source through at least one resistor. This control circuit generates a first control signal and a second control signal that are dependent on the voltage source, and thus can be easily controlled. The transistor is advantageously a low cost switch.

The embodiments of the switching circuit according to the invention, the control circuit according to the invention, the television according to the invention and the method according to the invention correspond to the embodiments of the receiver according to the invention.

These and other aspects of the invention will be apparent and become apparent upon reference to the embodiment (s) described hereinafter.

The receiver 1 according to the invention comprises a switching circuit 2 according to the invention and a control circuit 3 according to the invention.

The switching circuit 2 comprises two first switches 21, 22, for example a diode, and two second switches 23, 24, for example a diode. The anode of the diode 21 is grounded, for example, via an element 65 comprising a capacitor and is coupled to a first non-common point of the first series circuit 61, 62 comprising resistors 61, 62. The second non-common point of the resistors 61, 62 is coupled to the first input 11 through an element 13 comprising an anode of the diode 22, a high pass filter 16, and a capacitor, for example. . The first input 11 is also coupled to the mid band filter 15.

The cathode of the diode 22 is coupled to the filter input of the low pass filter 17, for example via an element 66 comprising a capacitor, and to an element 67 comprising a capacitor, for example. Is also bonded to the anode of 24). The cathode of diode 24 is coupled to the cathode of diode 21 and the cathode of diode 23, grounded through resistor 63, and coupled to cathode of diode 22 through resistor 64. The anode of the diode 23 is coupled to the second input 12 via an element 14 comprising a capacitor, for example.

The control circuit 3 comprises a third switch 31, for example in the form of a first transistor 31 (npn), the emitter of which is grounded and the collector (first contact) is a first series circuit. Coupled to the common point of 61 and 62, and coupled to the first voltage source 77 and 78 via resistors 73 and 76; The base (second contact) of the first transistor 31 is coupled via a resistor 75 to a common point of the second series circuits 71, 72 including the resistors 71, 72. The first non-common point of 72 is coupled to the anode of the diode 23 and the second non-common point is coupled to the anode of the diode 24. The control circuit 3 also comprises a fourth switch 32, for example in the form of a second transistor 32 (npn).

The commonality of the second series circuits 71, 72 is also coupled to the collector (first contact) of the second transistor 32 (npn), and through the resistor 74 and resistor 76 the first voltage source 77, 78). The emitter of the second transistor 32 is grounded and the base (second contact) is coupled to the second voltage source 80, 81 via a resistor 79. Both voltage sources 77, 78, and 80, 81 include internal resistors 77, 80 and sources 78, 81.

The receiver 1 plays the following roles. In a first mode, such as the television mode, for example, the first voltage sources 77, 78 are switched off and the second voltage sources 80, 81 are switched on. As a result, the first transistor 31 becomes non-conductive, the second transistor 32 becomes conductive, and the first signal, such as a television signal arriving at the first input 11, is directed to the mid-band filter 15. And flows through element 13 to high pass filter 16 and through element 13 and diodes 22 and 66 to low pass filter 17. A second signal, such as a frequency modulated radio signal arriving at the second input 12, is blocked by non-conductive diodes 23, 24.

In a second mode, such as the radio mode, for example, the first voltage sources 77, 78 are switched on and the second voltage sources 80, 81 are switched off. As a result, the first transistor 31 is conductive, the second transistor 32 is nonconductive, the first diodes 21 and 22 are nonconductive, and the second diodes 23 and 24 are conductive, The first signal, such as a television signal arriving at the first input 11, is blocked by the nonconductive diode 22. A second signal, such as a frequency modulated radio signal reaching the second input 12, now flows through the element 14, the conductive diodes 23, 24 and the element 67 to the low pass filter 17.

In both modes, one low pass filter 17 can be advantageously used with respect to both inputs 11, 12. By isolating the inputs 11, 12 from each other via at least two diodes 23, 21, only one diode 21 (by adding one or more other elements) between the inputs 11, 12 is provided. Compared to the prior art US 6,020,936 where coupling is present, the inputs 11, 12 in the receiver 1 according to the invention are much better isolated from each other, and this conventional diode 21 is a diode It is coupled to the anode of the diode 23 rather than the cathode of 23. Even a strong second signal, such as a strong radio signal, can no longer disturb any first signal, such as a television signal. Due to this good isolation, the first diodes 21, 22 and the second diodes 23, 24 now have a (separate) first control signal arriving through the first series circuit of the resistors 61, 62, It requires a second control signal that arrives through the second series circuit of resistors 71 and 72. When supplying a second control signal to the non-common point of the semi-serial second diodes 23, 24, one of the first diodes 21 favors the commonality of these semi-serial second diodes 23, 24. Can be combined.

In the first mode, resistor 63 forms a voltage divider with resistors 62 and 73 for first voltage sources 77 and 78, thereby allowing both second diodes 23 and 24 to have improved non-conductivity ( This allows the voltage at the anodes of these first diodes to be biased in reverse for the voltage at their cathode). As a result, intermodulation products due to nonlinearity of the switching diodes are avoided.

The present invention is based in particular on the insight that more switches in the combination lead to more isolation, in particular one of the first switches 21, 22, with a non-common point coupled to the second input 12. It is based on the basic idea that the non-common point (of the prior art) of the series second switches 23, 24 should be moved from the common point (of the invention) of these semi-serial second switches 23, 24.

The invention particularly addresses the problem of providing a receiver 1 which better isolates the inputs 11, 12 from each other, and in particular this type of receiver 1 is not shielded from the shielded second input 12. It is advantageous in that it no longer requires a different switching circuit 2 for the second input 12.

The switches 21 to 24 may be diodes or transistors. The transistors 31 and 32 may be npn transistors, pnp transistors, FETs, MOSFETs, or the like, and may include other embodiments of general switches. These elements may be more complex, other elements will not be excluded, and certain elements (such as resistor 76 or resistors 73, 74) may be combined and / or deleted and further inputs may be made. And / or additional filters and / or additional modes will not be excluded, all of which do not depart from the scope of the invention.

For example, each filter 15 to 17 may have an inductor in series. Between the input 11 and the element 13, for example, both sides are respectively grounded through inductors La and Lb, and the parallel circuits of the capacitor Cb and the inductor Lc are coupled in series with the capacitor Ca. There may be an element group of capacitor Ca. Instead of the element 14 being coupled to the resistor 71 and the anode of the diode 23, for example, it is coupled to the input 12, through the capacitor Cw to the anode of the diode 23, and the capacitor ( Both sides of Cy are grounded, the first side (coupled to the parallel circuit) passes through the inductor Ly, and the second side (coupled to the anode) connects the series circuit of the inductor Lz and the capacitor Cz. There may be a group of elements of a parallel circuit of capacitor Cx and inductor Lx, passing through and having a common point coupled to resistor 71 in this series circuit. And in series with the low pass filter 17, for example a parallel circuit of a capacitor and a resistor.

It is to be noted that the foregoing embodiments are illustrative rather than limiting of the invention and that those skilled in the art can design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps other than those listed in a claim. Singular expressions preceding an element do not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The simple fact that certain means are recited in different dependent claims does not indicate that a combination of these specific means cannot be used advantageously.

The invention is applicable to a receiver comprising a switching circuit and a control circuit for controlling such a switching circuit.

Claims (10)

A first input to receive a first signal; A second input to receive a second signal; A switching circuit having at least two first switches to be activated in the first mode and at least two second switches to be activated in the second mode; And A receiver comprising a control circuit for controlling the switching circuit, At least one said first switch and at least one said second switch together isolate at least one input from another input, said control circuitry supplying a first control signal to said first switch and supplying a second control signal. And supply to the second switch. The receiver of claim 1, wherein the first switch is a diode whose anode is coupled to the first input through one or more elements, and the second switch is a diode whose cathodes form a common point. . 3. The method of claim 2, wherein a cathode of one of the first switches is coupled to the common point, and another cathode of the first switches is coupled to a filter input through one or more elements, wherein one of the second switches Wherein an anode of is coupled to the second input through one or more elements and an anode of the second switch is coupled to the filter input through one or more elements. 4. A receiver as claimed in claim 3, wherein the receiver comprises a low pass filter comprising filter inputs for low pass filtering television signals and radio signals. 5. The control circuit of claim 4, wherein the control circuit comprises a third switch having a first contact coupled to a common point of a first series circuit of two resistors, and a non-common point of the two resistors coupled to an anode of the first switch. Wherein the control circuit further comprises a fourth switch having a first contact coupled to a common point of a second series circuit having two resistors with the second contact of the third switch, the non-common point of the two resistors Is coupled to an anode of the second switch, and the common point of the second switch is grounded through a resistor. 6. The method of claim 5, wherein the third switch comprises a first transistor, the fourth switch comprises a second transistor, the first contact of the transistor is a collector, the second contact of the transistor is a base, The emitter of the transistor is grounded, each collector is coupled to a first voltage source through at least one resistor, the base of the first transistor is coupled to a collector of the second transistor through a resistor, and And the base is coupled to the second voltage source through at least one resistor. 12. A switching circuit for use in a receiver comprising a first input for receiving a first signal and a second input for receiving a second signal, the switching circuit comprising: at least two first switches to be activated in a first mode; A switching circuit having at least two second switches to be activated in two modes, the switching circuit comprising: At least one of the first switch and at least one of the second switches together isolate at least one of the inputs from the other. A first input for receiving a first signal, a second input for receiving a second signal, and at least two first switches to be activated in a first mode, and at least two second switches to be activated in a second mode; A control circuit for use in a receiver comprising a switching circuit, the control circuit controlling the switching circuit, At least one of the first switches and at least one of the second switches together isolate at least one of the inputs from the other, the control circuitry sends a first control signal to the first switch and the second control signal to the It supplies to a 2nd switch, The control circuit characterized by the above-mentioned. A switching circuit having a first input for receiving a first signal, a second input for receiving a second signal, at least two first switches to be activated in a first mode and at least two second switches to be activated in a second mode And a receiver comprising a control circuit for controlling the switching circuit, At least one of the first switch and at least one of the second switches together isolate at least one of the inputs from the other, and wherein the control circuit is configured to provide a first control signal to the first switch and a second control signal to the second switch. A television comprising a receiver, characterized in that it is supplied to two switches. Receiving a first signal at a first input; Receiving a second signal at a second input; Activating at least two first switches in a first mode; Activating at least two second switches in a second mode; And A method comprising controlling the switching, comprising: At least one of the first switches and at least one of the second switches together isolate at least one of the inputs from the other, wherein the controlling step includes supplying a first control signal to the first switch and a second Supplying a control signal to the second switch.