Electrical / electronic circuit and method for detecting the activation of a secondary access point

Abstract

For the purpose of creating an electrical / electronic circuit for detecting the activation of a secondary access point, which is designed to be as space-saving and cost-effective as possible, an electrical / electronic circuit is presented comprising a primary side P with a first potential, a secondary side S having the secondary access point with a second potential, wherein the second potential is between two connecting lines, wherein the primary side P has an astable flip-flop with a comparator K having an impedance-dependent oscillation frequency of an alternating voltage generated by a voltage supply V. A special feature of this electrical / electronic circuit is that the secondary side S of the electrical / electronic circuit has a rectifier G, in particular connected to the two connecting lines, wherein the rectifier G is connected in parallel to the primary side P with two lines each connected to a Y-capacitor C1, C2, in a galvanically isolated manner, wherein a capacitor C3 is connected in parallel to the rectifier G, the capacitor C3 can be bridged by an auxiliary switch NS of the auxiliary switch which is to be influenced when actuated, so that when bridged the resulting oscillation frequency of the astable flip-flop changes as an indicator of the actuation of the secondary access point.

Description

[0001] The invention relates to an electrical / electronic circuit for detecting the actuation of a secondary access point for controlling or operating an electrical / electronic device, comprising a primary side having a first potential, a secondary side having the access point and having a second potential, wherein the second potential exists between two connecting lines, wherein the primary side has an astable flip-flop with a comparator with an impedance-dependent oscillation frequency of an alternating voltage generated by a voltage supply.

[0002] Furthermore, the invention relates to a method for detecting the actuation of a secondary access point for controlling or operating an electrical / electronic device having such an electrical / electronic circuit.

[0003] Various electrical / electronic circuits for detecting the activation of a secondary access point for controlling or operating an electrical / electronic device are known from the prior art. For the purposes of the invention, secondary access points are understood to include, for example, extensions, binary inputs, or the like.

[0004] A disadvantage of previously known electrical / electronic circuits for detecting the actuation of a secondary access point is that, although they can provide a potential on the secondary side that is galvanically separated from the primary side, this requires an additional power supply on the secondary side, in particular a space-consuming and cost-intensive optocoupler and / or a power supply.

[0005] Based on this discussed prior art, the object of the invention is to create an electrical / electronic circuit for detecting the actuation of a secondary access point, which is designed to be as space-saving and cost-effective as possible.

[0006] This object is achieved by an electrical / electronic circuit for detecting the actuation of a secondary access point, wherein the secondary side of the electrical / electronic circuit has a rectifier, in particular connected to the two connecting lines, wherein the rectifier is connected in parallel and galvanically isolated to the primary side by two lines each connected to a Y capacitor, wherein a capacitor is connected in parallel to the rectifier, the capacitor being bridgeable by an extension switch of the extension which is to be influenced during actuation, so that when bridging the resulting oscillation frequency of the astable flip-flop changes as an indicator of the actuation of the secondary access point.

[0007] The core idea of ​​the invention is that the primary side has an astable multivibrator with a comparator having an impedance-dependent oscillation frequency of an alternating voltage generated by a power supply, wherein the secondary side is designed to be bridgeable, so that upon bridging, the resulting oscillation frequency of the astable multivibrator changes as an indicator of the actuation of the secondary access point. The electrical / electronic circuit according to the invention for detecting the actuation of a secondary access point for controlling or operating an electrical / electronic device specifically avoids the use of a space-consuming and cost-intensive optocoupler and / or a power supply. For this purpose, the secondary side of the electrical / electronic circuit has a rectifier, in particular connected to the two connecting lines.Such a rectifier can be designed, for example, as a bridge rectifier, a single-pulse center-point circuit, or a two-pulse center-point circuit. In the electrical / electronic circuit according to the invention, the rectifier is connected to the primary side in parallel and galvanically isolated fashion via two lines, each connected to a Y capacitor. A particularly advantageous feature is that such a configuration achieves galvanic isolation that meets SELV requirements.

[0008] Particularly cleverly within the scope of the invention, a capacitor is connected in parallel with the rectifier. This capacitor can be bridged by an extension switch of the extension, which can be influenced upon actuation, so that when the capacitor is bridged, the resulting oscillation frequency of the astable flip-flop changes as an indicator of the activation of the secondary access point. The detection of the oscillation frequency change is preferably carried out using a microcontroller connected to the astable flip-flop. To amplify the signal, i.e., the change in the resulting oscillation frequency, a resistor is preferably connected in parallel with the rectifier in addition to the capacitor.

[0009] This advantageously creates an electrical / electronic circuit for detecting the actuation of a secondary access point for controlling or operating an electrical / electronic device, which does not require an additional power supply on the secondary side, thus eliminating the need to use a space-consuming and cost-intensive optocoupler and / or a power supply.

[0010] According to a particularly preferred embodiment of the electrical / electronic circuit for detecting the actuation of a secondary access point, the capacitor has a capacitance of at least 20 nF, in particular at least 100 nF. This allows the change in the oscillation frequency to be particularly well detected by the astable multivibrator with the comparator.

[0011] According to a particularly preferred development of the electrical / electronic circuit for detecting the operation of a secondary access point, a resistor, in particular a resistor less than 100 kOhm, is connected between the two Y capacitors. This results in the advantage that the resistance provided in an extension line, for example 50 kOhm, is considerably lower than the resistance of an open switch or the extension line itself. This minimizes the influence of environmental influences on the frequency at the flip-flop.

[0012] Furthermore, the invention relates to a method for detecting the actuation of a secondary access point for controlling or operating an electrical / electronic device with an electrical / electronic circuit according to the invention, comprising the steps: - Relative detection of the impedance-dependent oscillation frequency change by operating the access point's extension switch, - Identification as activation of the secondary access point when the oscillation frequency change reaches a definable value.

[0013] In the context of the method according to the invention, in a first step the impedance-dependent oscillation frequency change is detected by the actuation of the extension switch of the access point.

[0014] Subsequently, the activation of the secondary access point is identified when the change in oscillation frequency reaches a definable value. For example, a change in oscillation frequency in the range of approximately 1 kHz to 50 kHz within a period of 50 ms to 500 ms can be identified as activation. Such values ​​lead to a particularly reliable interpretation of the activation of the secondary access point.

[0015] The invention is described below with reference to an exemplary embodiment in the accompanying figures. It shows: Fig. 1: a circuit diagram of a possible embodiment of the electrical / electronic circuit according to the invention for detecting the actuation of a secondary access point.

[0016] Fig. 1 shows a circuit diagram of a possible embodiment of the electrical / electronic circuit according to the invention for detecting the actuation of a secondary access point.

[0017] A primary side P with a first potential can be seen, and a secondary side S having the secondary access point with a second potential, wherein the second potential exists between two connecting lines. The primary side P also comprises an astable flip-flop with a comparator K with an impedance-dependent oscillation frequency of an alternating voltage generated by a voltage supply V. In the illustrated embodiment of the invention, the secondary side S comprises a rectifier G connected to the two connecting lines, which in this case is designed as a bridge rectifier comprising the diodes D1-D4. Galvanic isolation between the primary side P and secondary side S is achieved in this case by the two Y capacitors C1, C2. The power supply is provided by a voltage supply V in the primary side P. The extension can be connected to the extension connecting lines NS_A or NS_B.

[0018] A capacitor C3 and a resistor R5 are connected in parallel to the rectifier G. Both the capacitor C3 and the resistor R5 can be bridged by an extension switch NS of the extension, which is influenced upon actuation, so that when the switch is bridged, the resulting oscillation frequency of the astable multivibrator changes, indicating the actuation of the secondary access point. Bridging changes the resulting resonant circuit and thus its impedance-dependent oscillation frequency, as the influence of the capacitor C3 and the resistor R5 can be switched on or off by operating the extension switch.

[0019] A particularly advantageous feature of the inventive electrical / electronic circuit for detecting the activation of a secondary access point is that capacitor C3 has a capacitance of at least 20 nF, in particular at least 100 nF. This ensures that the capacitance of this capacitor C3 for a 100-meter-long multi-wire cable is significantly greater than the capacitance of the cables themselves. This makes the use of long extension lines possible.

[0020] The invention is described using an exemplary embodiment. Without departing from the scope of the applicable claims, numerous further possibilities for implementing it will become apparent to a person skilled in the art without the need for detailed explanation within the scope of these statements. List of reference symbols C capacitor D-diode G Rectifier NS extension switch NS_A,B extension line K Comparator P Primary side R resistance S Secondary side V Power supply

Claims

[1] Electrical / electronic circuit for detecting the actuation of a secondary access point for controlling or operating an electrical / electronic device, comprising a primary side (P) with a first potential, a secondary side (S) having the secondary access point with a second potential, wherein the second potential exists between two connecting lines, wherein the primary side (P) has an astable flip-flop with a comparator (K) with an impedance-dependent oscillation frequency of an alternating voltage generated by a voltage supply (V), characterized bythat the secondary side (S) of the electrical / electronic circuit has a rectifier (G), in particular connected to the two connecting lines, wherein the rectifier (G) is connected in parallel and galvanically isolated to the primary side (P) by two lines each connected to a Y capacitor (C1, C2), wherein a capacitor (C3) is connected in parallel to the rectifier (G), the capacitor (C3) can be bridged by an extension switch (NS) of the extension which is to be influenced during actuation, so that when bridging the resulting oscillation frequency of the astable flip-flop changes as an indicator of the actuation of the secondary access point. [2] Electrical / electronic circuit according to claim 1, characterized by that the capacitor (C3) has a capacitance of at least 20 nF, in particular at least 100 nF. [3] Electrical / electronic circuit according to claim 1 or 2, characterized bythat the rectifier (G) comprises a bridge rectifier. [4] Electrical / electronic circuit according to one of claims 1 to 3, characterized by that the rectifier (G) comprises a single-pulse center-point circuit or a two-pulse center-point circuit. [5] Electrical / electronic circuit according to one of claims 1 to 4, characterized by that the secondary access point has an extension. [6] Electrical / electronic circuit according to one of claims 1 to 5, characterized by that a resistor (R6) is connected between the Y capacitors (C1, C2). [7] Electrical / electronic circuit according to one of claims 1 to 6, characterized by that a resistor (R5) is connected in parallel to the rectifier (G). [8] A method for detecting the actuation of a secondary access point for controlling or operating an electrical / electronic device with an electrical / electronic circuit according to one of claims 1 to 7 for detecting the actuation of a secondary or supplementary access point for controlling or operating an electrical / electronic device, comprising the steps of: - Relative detection of the impedance-dependent oscillation frequency change by operating the extension switch (NS) of the access point, - Identification as activation of the secondary access point when the oscillation frequency change reaches a definable value.

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