EP2595908B1 - Electric circuit with connecting part protected against incorrect coupling - Google Patents

Description

The present invention is in the field of reverse polarity protection in connection parts of electrical circuits. It relates to an electrical circuit and a combination of an electrical circuit and a multi-wire electrical line, according to the preambles of the independent claims. A preferred application is a yarn cleaner measuring head, as used for quality control on spinning or winding machines.

STATE OF THE ART

To ensure the yarn quality so-called yarn cleaners are used on spinning or winding machines. Such a yarn cleaner is z. B. from the EP-1'249'422 A2 known. It includes a yarn cleaner gauge with at least one sensor which senses the moving yarn and measures at least one parameter of the yarn. Frequently used sensor principles are capacitive (see eg EP-0'924'513 A1 ) or the optical (see eg WO 93/13407 A1 ). The aim of yarn cleaning is to detect defects such as thick spots, thin spots or foreign substances in the yarn, to evaluate them according to certain quality criteria and to eliminate them if necessary. The structure of a Garnreinigermesskopfes is in the US Pat. No. 6,422,072 B1 or the EP-1'302'426 A2 described.

For both the spinning and winding machines, each yarn cleaner measuring head is equipped with a connection cable that is a few decimeters to a few meters long for power supply and data transmission. This connection cable is connected directly or indirectly to a bus line to which on the one hand further yarn cleaner measuring heads and on the other hand a central cleaning control unit are connected. Usually, connecting cables are produced especially for the respective application used. From the WO-2009/143642 A1 is a yarn cleaner measuring head with a detachable cable connection known. The yarn cleaner gauge comprises a gauge head housing and an electrical circuit housed therein. The electrical circuit can be connected via a measuring head side connection with an electrical connection cable. In this case, the measuring head-side connection is designed to produce a releasable connection between the yarn cleaner measuring head and the connection cable. Such a detachable connection is on the one hand advantageous because it makes the removal, installation or replacement of Garnreinigermesskopf significantly easier and safer. On the other hand, it brings with it the danger of "reverse polarity". This is understood to mean the production of electrical connection connections that are not provided by the device manufacturer and may possibly cause damage to persons and / or property.

1. 1. Mechanischer Verpolungsschutz. Durch eine nicht rotationssymmetrische mechanische Gestaltung von Stecker und Buchse wird sichergestellt, dass die beiden elektrischen Anschlüsse (Plus und Minus) nicht in falscher Polarität hergestellt werden können.
2. 2. Elektrischer Verpolungsschutz. Durch geeignete Schaltungen und Bauteile wird sichergestellt, dass beim Anlegen elektrischer Spannungen in falscher Polarität im angeschlossenen Gerät kein Schaden entsteht. Solche Schaltungen und Bauteile können Dioden, Gleichrichter oder Relais umfassen.

When DC powering a device, two types of reverse polarity protection are known:

1. 1. Mechanical reverse polarity protection. A non-rotationally symmetrical mechanical design of plug and socket ensures that the two electrical connections (positive and negative) can not be made in the wrong polarity.
2. 2. Electrical reverse polarity protection. Suitable circuits and components ensure that no damage occurs when electrical voltages are applied in the wrong polarity in the connected device. Such circuits and components may include diodes, rectifiers or relays.

The electrical reverse polarity protection in the DC power supply of a device is a relatively simple case, because only two similar connections are involved, which differ only by their polarity (plus and minus). With the yarn cleaner measuring head, the situation is more complicated in that different power supplies and, in addition, the transmission of various data must be made here via a single connection cable. This typically requires about ten parallel lines. The voltages applied to the various lines are completely different and can vary from zero (ground connection) over a few volts (logic signals) up to about 60 V depending on the line (Power supply for the cutting tool) amount. If the latter high voltage is accidentally applied to a line not intended for it, damage to persons and / or to the yarn cleaner system may result. Not only the incorrectly connected yarn cleaner measuring head, but also other measuring heads, the central cleaner control unit and even the central machine control unit can be affected by bus cables. Such damage must be avoided.

Of course, a mechanical reverse polarity protection can also be used in the yarn cleaner. However, simple mechanical measures can be overcome by applying high forces. A secure mechanical reverse polarity protection z. As the commercially available connector of the widely used type D-Sub 15 with 15 contact elements. However, such connectors are relatively expensive and would increase the cost in large quantities Garnreinigermessköpfe. Therefore, cheaper connectors such. Hirose DF11-16DS-2C available from Hirose Electric Co., Ltd., Tokyo, Japan.

DE 4 103 634 A1 and WO 02/43192 A2 disclose electrical circuits according to the preamble of claim 1.

PRESENTATION OF THE INVENTION

It is therefore an object of the present invention to provide a non-mechanical reverse polarity protection for an electrical circuit, comprising a circuit-side connecting part with a plurality of contact elements for a detachable electrical connector. A further object is to provide a non-mechanical reverse polarity protection for a combination of an electric circuit and a multi-core electrical line, which combination includes a releasable electrical connection of a first connection part with a plurality of contact elements and a second connection part with a plurality of contact elements. Particular attention should be paid to the application of the circuit and the combination in connection with a yarn cleaning system.

These and other objects are achieved by the inventive electrical circuit and the inventive combination of an electrical circuit and an electrical connection cable, as in the independent claims are defined. Advantageous embodiments are given in the dependent claims.

The invention is based on the idea of a "geometric" reverse polarity protection. This is based neither on the mechanical design of the electrical connection nor on a special electrical circuit. Rather, the occupancy of the contact elements is designed such that at a reverse polarity at least no damage to things and / or people can be done. Ideally, even the yarn cleaner system connected to the common bus line will continue to function, with the exception of the polarity-reversed yarn cleaner measuring head.

Accordingly, the electrical circuit according to the invention comprises a circuit-side connecting part with a plurality of contact elements for a detachable electrical connection, wherein all contact elements of the circuit-side connecting part are arranged such that they can be imaged on themselves by at least one congruent image different from the identical image. The contact elements are so occupied in relation to the circuit that in the at least one congruent image only electrically compatible contact elements are imaged onto each other.

Which contact elements are electrically compatible with each other and which are not, a know the electrical circuit expert in the field of electrical engineering very well. So z. B. two contact elements for signal input voltages of the same magnitude electrically compatible with each other, even if the two signals carry very different information. On the other hand, a contact element which has been grounded and connected to a contact element for the power supply would be electrically incompatible with one another because, in their mutual contacting, the voltage supply would be short-circuited and the voltage would be applied to circuit elements which are not designed for this purpose.

1. (a) direkt miteinander verbundene oder für denselben Zweck vorgesehene Kontaktelemente werden aufeinander abgebildet;
2. (b) jedes zur Übertragung einer Eingangsspannung in die Schaltung vorgesehene Kontaktelement mit einem ersten Eingangswiderstand wird auf ein Kontaktelement mit einem zweiten Eingangswiderstand, der mindestens tausendmal grösser als der erste Eingangswiderstand ist, oder auf ein zur Übertragung einer Eingangsspannung derselben Grössenordnung in die Schaltung vorgesehenes Kontaktelement abgebildet; und
3. (c) jedes zur Übertragung einer Ausgangsspannung aus der Schaltung vorgesehene Kontaktelement wird auf ein ebenfalls zur Übertragung einer Ausgangsspannung aus der Schaltung vorgesehene Kontaktelement abgebildet.

Based on such and similar considerations, some criteria for the assignment of the contact elements can be set up. The contact elements should be occupied in relation to the inventive electrical circuit such that at least one Congruence mapping at least two and preferably all of the following three criteria are met:

1. (a) directly connected or intended for the same purpose contact elements are mapped to each other;
2. (b) each contact element having a first input resistance provided for transmitting an input voltage to the circuit is applied to a contact element having a second input resistance which is at least a thousand times greater than the first input resistance, or to a contact element provided for transmitting an input voltage of the same magnitude to the circuit displayed; and
3. (C) each provided for transmitting an output voltage from the circuit contact element is mapped to a likewise provided for transmitting an output voltage from the circuit contact element.

The directly interconnected contact elements mentioned in criterion (a) can, for. B. be mass connections. The input voltage mentioned in criterion (b) is z. B. a substantially constant supply voltage having an absolute value between 3 V and 120 V or a time-varying signal voltage having a value between -24 V and +24 V. The in criterion (b) said second input resistance is preferably at least 10 kΩ, so that the contact element with the second input resistance is in any case high impedance. The contact element with the second input resistance mentioned in criterion (b) may be a contact element not used in the circuit. The output voltage mentioned in criterion (c) is z. B. a time-varying signal voltage with a value between -12 V and +12 V.

In a particular embodiment, at most half of all the contact elements in the circuit may be utilized, and each contact element used is mapped to an unused contact element.

In a preferred embodiment, the electrical circuit according to the invention is installed in a yarn cleaner measuring head. The contact elements are then preferably provided for purposes of the following amount: first constant supply voltage, preferably between +20 V and +60 V; second constant supply voltage, preferably between +10 V and +15 V; third constant supply voltage, preferably between +3 V and +5 V; Signal line for a one-sided serial transmission of an input signal into the circuit, preferably between 0 V and 5 V; Signal line for a one-sided serial transmission of an output signal from the circuit, preferably between 0 V and 5 V; Signal line for a two-sided serial signal transmission, preferably between -10 V and +15 V; Ground connection. In addition to the yarn cleaner mentioned as an example, however, the invention can be used in many other devices in various technical fields.

The congruence mapping is z. B. a rotation, preferably by 180 °, and / or a translation. The releasable electrical connection may be a plug connection with 16 contact elements, which are arranged in two rows of eight equidistant contact elements.

Furthermore, the invention relates to a combination of an electrical circuit and a multi-core electrical line. The combination includes a releasable electrical connection of a first connecting part with a plurality of contact elements and a second connecting part with a plurality of contact elements. The contact elements of the two connecting parts are arranged such that they can be connected to one another in at least two different ways, which emerge from one another by at least one congruent image of one of the two connecting parts which is different from the identical image. The contact elements of the first connection part and / or the contact elements of the second connection part are so occupied that in the at least one match image only electrically compatible contact elements are mapped to each other. At least two of the three aforementioned criteria (a) to (c) and preferably all three criteria (a) to (c) should be fulfilled.

The preferred embodiments of the inventive combination are analogous to those of the inventive electrical circuit, as described above. The detachable electrical connection may be located at any point in the combination according to the invention. In a preferred embodiment it is a plug connection between the electrical circuit and an electrical connection cable; the first connecting part is a circuit-side connecting part, preferably a plug, and the second connecting part is a cable-side connecting part, preferably a coupling.

The invention is applicable to any electrical circuit. Although a yarn cleaner system is given as a preferred application example in this document, this should by no means be understood as limiting the generality of the invention.

Thanks to the invention, the effects of reverse polarity are minimized. Damage to persons and / or property is virtually ruled out, so that the device containing the circuit, for example a yarn cleaner measuring head, is safer. A mechanical and / or electrical reverse polarity protection can be made less expensive or omitted altogether. As a result, the device containing the circuit is cheaper to produce.

TITLE OF DRAWINGS

Figur 1

zeigt eine erfindungsgemässe Kombination einer elektrischen Schaltung in einem Garnreinigermesskopf und eines elektrischen Anschlusskabels in einer teilweise offengelegten perspektivischen Ansicht.

Figuren 2-5

zeigen vier Ausführungsformen einer elektrischen Steckverbindung in einer erfindungsgemässen Kombination einer Schaltung und eines Kabels in einer schematischen Draufsicht.

Hereinafter, preferred embodiments of the invention will be explained in detail with reference to the drawings.

FIG. 1

shows a combination according to the invention of an electrical circuit in a Garnreinigermesskopf and an electrical connection cable in a partially exposed perspective view.

Figures 2-5

show four embodiments of an electrical connector in an inventive combination of a circuit and a cable in a schematic plan view.

EMBODIMENT OF THE INVENTION

In FIG. 1 illustrates a preferred application of the present invention, namely an electronic grain cleaner gauge 1 with a detachable electrical Connecting Cable 4. The yarn cleaner measuring head 1 includes a measuring head housing 11 for receiving a yarn sensor, an electronic circuit, a yarn cutting tool and / or other components. The connection cable 4 serves both the power supply of the yarn cleaner measuring head 1 and the data transmission to and from the yarn cleaner measuring head 1. Preferably, it is a multi-core shielded connection cable. In the example of FIG. 1 For example, the connection cable 4 is based on a commercially available 15-wire game port cable in which a coupling has been mounted in a coupling housing 5 at a measuring head end. At the end facing away from Garnreinigermesskopf 1 end the connection cable 4 carries a plug 7, z. As a commercially available connector of the widely used type D-Sub 15, for connecting the connecting cable 4 to a (not shown) Purigersektionselektronik, to a (not shown) bus line, which is connected to a central cleaner control unit, or to another component.

In FIG. 1 the measuring head housing 11 is partially exposed, and the coupling housing 5 is released from the measuring head housing 11. Thanks to the disclosure of the measuring head housing 11, a printed circuit board 2 accommodated in the interior of the measuring head housing 11 can be seen, which carries at least parts of an electrical circuit 21. In the printed circuit board 2 is a measuring slot 22, which serves for receiving a (not shown) to be cleaned yarn and to which a (not shown) yarn sensor for scanning the yarn is attached.

To produce a detachable electrical connection between the circuit 21 and the connecting cable 4, the yarn cleaner measuring head 1 is equipped with a circuit-side connecting part 3 and the connecting cable 4 with a cable-side connecting part 6. In the embodiment of FIG. 1 the detachable electrical connection is designed as a plug connection. The circuit-side connecting part 3 may be embodied as a plug mounted on the printed circuit board 2. Preferably, it is an indirect multi-pin connector 3, the z. B. is soldered on the circuit board 2. At its Meßkopfseitigen end, the connecting cable 4 carries the matching connector 3 to the coupling 6, z. Hirose DF11-16DS-2C, as available from Hirose Electric Co., Ltd., Tokyo, Japan.

The plug 3 and the coupling 6 together form a connector. Of course, in this connector, a mechanical Verpolungsschutz be provided, which should prevent the plug 3 is inserted in an unforeseen way in the coupling 6, resulting in a risk to persons and property would threaten. However, experience shows that mechanical reverse polarity protection can be bypassed intentionally or unintentionally. Therefore, further measures for reverse polarity protection are desired as proposed by the present invention.

In addition to the electrical connection, a detachable mechanical connection between the measuring head housing 11 and the coupling housing 5 is provided. It is designed as a snap connection or snap connection. The electrical and mechanical connections are separate in the embodiment discussed herein, but need not necessarily be.

In FIG. 2 is a first embodiment of an electrical connector in an inventive combination of a circuit 21 and a cable 4 (see FIG. 1 ). A circuit-side connecting part 3 may, for. B. be designed as a plug and a cable-side connecting part 6 as a matching coupling. Both connecting parts are in FIG. 2 shown schematically as rectangles; on mechanical details of the connection is not entered. Plug 3 and coupling 6 each have 16 contact elements 8, z. B. in the form of contact pins or contact openings, which are arranged and designed so that in the connected state, the associated contact elements 8 contact each other electrically. In the embodiment of FIG. 2 the 16 contact elements 8 are arranged in two rows of eight contact elements 8 with a mutual distance of 2 mm and numbered with corresponding atomic numbers 1-16.

The matrix-shaped arrangement of the contact elements 8 in the connector of FIG. 2 allows a rotation (indicated by an arrow 91) of the coupling 6 relative to the plug 3 by 180 ° about a center of rotation 90, wherein after rotation 91 again an electrical plug connection between the two connecting parts 3, 6 can be produced. (It is assumed here that a mechanical reverse polarity protection is absent or only insufficiently functioning.) The plug 3 and the coupling 6 can thus be connected to each other in two different ways, which emerge apart by a rotation 91 of the coupling 6. However, different contact elements 8 are associated with each other in the two types. Table 1 shows the two different assignments of the contact elements 8. Table 1 Connector contact element no. 1 2 3 4 5 6 7 8th 9 10 11 12 13 14 15 16 Coupling contact element no. (Before rotation) 1 2 3 4 5 6 7 8th 9 10 11 12 13 14 15 16 Coupling contact element no. (After rotation) 16 15 14 13 12 11 10 9 8th 7 6 5 4 3 2 1

The different contact assignments can be a problem without the inventive measures, because only one type is provided and in the other, unforeseen nature damage to persons and / or things may arise. The invention solves this problem by a geometric reverse polarity protection. In this case, the contact elements 8 are so occupied in relation to the circuit that during the rotation 91 only electrically mutually compatible contact elements 8 are imaged on each other. For this purpose, it is advantageous to make the assignment of the contact elements 8 according to specific criteria, which will be discussed below. An electrically compatible assignment is given by way of example in Table 2: Table 2 Connector contact element no. Usage Voltage (V) 1 ground connection 2 Not used 3 power supply +4 4 ground connection 5 power supply +15 6 ground connection 7 signal output 0..4 8th communication line -10 .. + 15 9 communication line -10 .. + 15 10 signal output 0..4 11 signal input 0..4 12 Not used 13 ground connection 14 signal input 0..4 15 power supply 20..60 16 ground connection

1. (a) Direkt miteinander verbundene oder für denselben Zweck vorgesehene Kontaktelemente 8 werden aufeinander abgebildet.
   Beispiele: Massenanschlüsse auf Steckerkontaktelementen Nrn. 1, 16 und 4, 13.
2. (b) Jedes zur Übertragung einer Eingangsspannung in die Schaltung 21 vorgesehene Kontaktelement 8 mit einem ersten Eingangswiderstand wird auf ein Kontaktelement 8 mit einem zweiten Eingangswiderstand, der mindestens tausendmal grösser als der erste Eingangswiderstand ist, oder auf ein zur Übertragung einer ähnlichen Eingangsspannung in die Schaltung 21 vorgesehenes Kontaktelement 8 abgebildet. Beispiele: Die Spannungsversorgung auf Steckerkontaktelement Nr. 3 und das Nutentrommelsignal auf Steckerkontaktelement Nr. 14 sind beide auf 4 V begrenzt und somit ähnlich. Die Spannungsversorgung auf Steckerkontaktelement Nr. 15 wird auf das nicht verwendete und somit hochohmige Steckerkontaktelement Nr. 2 abgebildet.
3. (c) Jedes zur Übertragung einer Ausgangsspannung aus der Schaltung 21 vorgesehene Kontaktelement 8 wird auf ein ebenfalls zur Übertragung einer Ausgangsspannung aus der Schaltung 21 vorgesehene Kontaktelement 8 abgebildet.
   Beispiele: Kommunikation auf Steckerkontaktelementen Nm. 8 und 9. Signalausgänge auf Steckerkontaktelementen Nrn. 7 und 10.

The inventive criteria are explained below with reference to the above occupancy example:

1. (a) Contact elements 8 directly connected or provided for the same purpose are mapped to each other.
   Examples: Bulk connections on plug contact elements Nos. 1, 16 and 4, 13.
2. (b) Each contact element 8 having a first input resistance provided for transmitting an input voltage to the circuit 21 is applied to a contact element 8 having a second input resistance at least a thousand times greater than the first input resistance or to a similar input voltage to the circuit 21 provided contact element 8 shown. Examples: The power supply on male contact element no. 3 and the keyway signal on male contact element no. 14 are both limited to 4 V and thus similar. The voltage supply on plug contact element no. 15 is mapped to the unused and thus high-resistance plug contact element no.
3. (C) Each provided for the transmission of an output voltage from the circuit 21 contact element 8 is imaged on a likewise provided for transmitting an output voltage from the circuit 21 contact element 8.
   Examples: Communication on plug contact elements Nm. 8 and 9. Signal outputs on plug contact elements Nos. 7 and 10.

FIG. 3 shows a second embodiment of an electrical connector in an inventive combination of a circuit 21 and a cable 4. Here, the outer shapes of the two connecting parts 3, 6 are circular, and the contact elements 8 are arranged on a circle. Because of the non-equidistant arrangement of the contact elements 8, the two connecting parts 3, 6 can be rotated by 120 ° and 240 ° with respect to each other about a center of rotation 90, wherein after each rotation 92, 93 again an electrical connector between the two connecting parts 3, 6 can be produced. So there are three different types of connections, whose contact assignments are summarized in Table 3 . Table 3 Circuit-side contact element no. 1 2 3 4 5 6 7 8th 9 Cable-side contact element No. (0 °) 1 2 3 4 5 6 7 8th 9 Cable-side contact element no. (120 °) 4 5 6 7 8th 9 1 2 3 Cable-side contact element no. (240 °) 7 8th 9 1 2 3 4 5 6

A third embodiment of the electrical connector is in FIG. 4 specified. Here, the congruence map is not a rotation, but a translation 94 of the one connecting part 6 with respect to the other connecting part 3. The circuit-side connecting part 3 has five contact elements 8, while the cable-side connecting part 6 has only three. Two contact elements 8 of the circuit-side connecting part 3 thus always remain unused. The contact assignments of the two possible types of connections are listed in Table 4 . Table 4 Circuit-side contact element no. 1 2 3 4 5 Cable-side contact element No. (before translation) 1 2 4 Cable-side contact element No. (after translation) 1 2 4

FIG. 5 shows a fourth embodiment of the electrical connector. The circuit-side connecting part 3 here has only a row of eight equidistant contact elements 8, while the cable-side connecting part 6 has two such rows, one of which always remains unused. The numbering of the contact elements 8 is analogous to FIG. 2 , As congruence mapping is both a rotation 95 by 180 ° and a translation 96 in question. This results in four possible connection types whose contact assignments are summarized in Table 5 . Table 5 Circuit-side contact element no. 1 3 5 7 9 11 13 15 Cable-side contact element No. (identical figure) 1 3 5 7 9 11 13 15 Cable-side contact element No. (only rotation) 15 13 11 9 7 5 3 1 Cable-side contact element No. (translation only) 2 4 6 8th 10 12 14 16 Cable-side contact element no. (Rotation and translation) 16 14 12 10 8th 6 4 2

Also in the embodiments of Figures 3-5 For example, a geometric reverse polarity protection according to the present invention can be used. For this purpose, electrical compatibility of the contact elements is produced by applying the mentioned criteria (a), (b) and / or (c). In the example of FIG. 5 can each be two pairs of interconnected contact elements 8 of the cable-side connecting part 6 (ie Nos. 1 and 2, 3 and 4, ..., 15 and 16), so that in the pure translation (fourth row of Table 5) the Criterion (a) is used: directly connected contact elements 8 are imaged onto each other. For electrical compatibility during rotation (lines 3 and 5 of Table 5) further measures are required.

For the sake of simplicity, the embodiments discussed above refer to the example of a plug connection between the circuit 21 and the connection cable 4 (see FIG FIG. 1 ). However, the present invention is not limited to this example. First of all, the detachable electrical connection does not need to be a plug connection. Clamping and other detachable electrical connections are also possible. And second, the releasable electrical connection may be at a different location from the combination of the circuit 21 and the electrical line connected to the circuit 21. The in FIG. 1 drawn D-Sub 15 plug 7 at the end facing away from the Garnreinigermesskopf 1 end of the connecting cable 4 is indeed mechanically well protected against reverse polarity. However, it would be conceivable to use a simpler and less expensive detachable electrical connection without mechanical reverse polarity protection at that point. In such an alternative solution, the inventive concept of geometric reverse polarity protection can be applied to the connection between the cable 4 and the (not shown) Purigersektionselektronik or the (not shown) bus line. Analogously, the geometric reverse polarity protection according to the invention can be applied to an electrical connection which is further away from the circuit 21 but which is electrically connected to the circuit 21.

The present invention is therefore not limited to the embodiments discussed above. With knowledge of the invention, the skilled person will be able to derive further variants, which also belong to the subject of the present invention. The invention is applicable to any electrical circuit.

LIST OF REFERENCE NUMBERS

1

Garnreinigermesskopf

11

Probe housing

2

circuit board

21

electrical circuit

22

measuring slot

3

circuit-side connecting part

4

connection cable

5

clutch housing

6

cable-side connecting part

7

Plug at the cable end facing away from the yarn cleaner measuring head

8th

contact elements

90

center of rotation

91,92,93,95

rotations

94.96

translations

Claims (15)

1. An electrical circuit (21) comprising a circuit-side connecting part (3) having multiple contact elements (8) for a detachable electrical connection, all contact elements (8) of the circuit-side connecting part (3) being arranged in such a manner that they are mappable on themselves by at least one congruent mapping (91-96) different from the identity mapping, and
   the contact elements (8) are assigned in relation to the circuit (21) in such a manner that, in the case of the at least one congruent mapping (91-96), only contact elements (8) which are electrically compatible with one another are mapped on one another,
   characterized in that
   the contact elements (8) are assigned in relation to the circuit (21) in such a manner that at least two and preferably three of the following criteria are fulfilled in the case of the at least one congruent mapping (91-96):

   (a) contact elements (8) which are directly connected to one another or provided for the same purpose are mapped on one another;

   (b) each contact element (8), which is provided for the transmission of an input voltage into the circuit (21), having a first input resistance is mapped on a contact element (8) having a second input resistance which is at least 1000 times greater than the first input voltage, or is mapped on a contact element (8) provided for the transmission of an input voltage of the same magnitude into the circuit (21); and

   (c) each contact element (8) provided for the transmission of an output voltage out of the circuit (21) is mapped on a contact element (8) also provided for the transmission of an output voltage out of the circuit (21).
2. The electrical circuit (21) according to claim 1, wherein the contact elements (8) which are directly connected to one another, mentioned in criterion (a), are ground terminals.
3. The electrical circuit (21) according to one of the preceding claims, wherein the input voltage mentioned in criterion (b) is a substantially constant supply voltage having an absolute value between 3 V and 120 V or a time variable signal voltage having a value between -24 V and +24 V.
4. The electrical circuit (21) according to one of the preceding claims, wherein the second input resistance mentioned in criterion (b) is at least 10 kΩ.
5. The electrical circuit (21) according to claim 4, wherein the contact element (8) mentioned in criterion (b) having the second input resistance is a contact element (8) which is not used in the circuit (21).
6. The electrical circuit (21) according to one of the preceding claims, wherein the output voltage mentioned in criterion (c) is a time variable signal voltage having a value between -12 V and +12 V.
7. The electrical circuit (21) according to one of the preceding claims, wherein the circuit (21) is installed in a yarn clearer measuring head (1).
8. The electrical circuit (21) according to claim 7, wherein the contact elements (8) are provided for purposes from the following set: first constant supply voltage, preferably between +20 V and +60 V; second constant supply voltage, preferably between +10 V and +15 V; third constant supply voltage, preferably between +3 V and +5 V; signal line for a one-sided serial transmission of an input voltage into the circuit (21), preferably between 0 V and 5 V; signal line for a one-sided serial transmission of an output signal out of the circuit (21), preferably between 0 V and 5 V; signal line for a two-sided serial signal transmission, preferably between -10 V and +15 V; ground terminal.
9. The electrical circuit (21) according to one of the preceding claims, wherein the congruent mapping (91, 92, 93, 95) is a rotation, preferably by 180°, and/or a translation (94, 96).
10. A combination of an electrical circuit (21) and a multicore electrical line (4), which combination contains a detachable electrical connection of a first connecting part (3) having multiple contact elements (8) and a second connecting part (6) having multiple contact elements (8),
    the contact elements (8) of the two connecting parts (3, 6) being arranged in such a manner that they are connectable to one another in at least two different ways, which arise from one another through at least one congruent mapping (91-96), which is different from the identity mapping, of one of the two connecting parts (3, 6),
    the contact elements (8) of the first connecting part (3) and/or the contact elements (8) of the second connecting part (6) being assigned in such a manner that in the case of the at least one congruent mapping (91-96), only contact elements (8) which are electrically compatible with one another are mapped on one another,
    characterized in that
    the contact elements (8) of the first connecting part (3) and/or the contact elements (8) of the second connecting part (6) are assigned in such a manner that in the case of the at least one congruent mapping (91-96), at least two and preferably all three of the following criteria are fulfilled:

    (a) contact elements (8) which are directly connected to one another or provided for the same purpose are mapped on one another;

    (b) each contact element (8), which is provided for the transmission of an input voltage into the circuit (21), having a first input resistance is mapped on a contact element (8) having a second input resistance which is at least 1000 times greater than the first input voltage, or is mapped on a contact element (8) provided for the transmission of an input voltage of the same magnitude into the circuit (21); and

    (c) each contact element (8) provided for the transmission of an output voltage out of the circuit (21) is mapped on a contact element (8) also provided for the transmission of an output voltage out of the circuit (21).
11. The combination according to claim 10, wherein the contact elements (8) directly connected to one another, mentioned in criterion (a), are ground terminals.
12. The combination according to claim 10 or 11, wherein the input voltage mentioned in criterion (b) is a substantially constant supply voltage having an absolute value between 3 V and 120 V or a time variable signal voltage having a value between -24 V and +24 V.
13. The combination according to one of claims 10-12, wherein the second input resistance mentioned in criterion (b) is at least 10 kΩ.
14. The combination according to one of claims 10-13, wherein the output voltage mentioned in criterion (c) is a time variable signal voltage having a value between -12 V and +12 V.
15. The combination according to one of claims 10-14, wherein the detachable electrical connection is a plug connection between the electrical circuit (21) and an electrical connection cable (4), the first connecting part (3) is a circuit-side connecting part, preferably a plug, and the second connecting part (6) is a cable-side connecting part, preferably a coupling.

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