EP2113887B1 - Key switch - Google Patents

Description

The invention relates to a key switch.

In automation technology key switches are often used to restrict certain operations on equipment and / or machinery to specific users.

In FIG. 1 is a commercially available control device 1 for operating a machine from automation technology, such as a machine tool, production machine and / or a robot shown having a commercially available mechanical key switch 2. With mechanical key switches, the key is scanned mechanically. However, mechanical key switches have the disadvantage that the frequently occurring in an automation environment dirt, which is usually in the form of liquids, dust particles or aggressive gases, can bring about the key switch in the operating device and can lead to malfunction. Furthermore, the mechanics of the key switch itself can be damaged.

Furthermore, mechanical key switches are subject to high wear due to the mechanical moving components and are relatively easy to manipulate.

Instead of a key switch, other identification systems are used, such as non-contact RFID systems. However, these systems are relatively expensive and expensive.

The US 5 268 560 A shows that by means of multiple excitation devices, the magnetic encoding of a key after its insertion process in a time-parallel manner is read out.

It is the object of the invention to ensure a particularly high level of security against inadmissible manipulation of a key or key switch.

The object is achieved by a key switch according to claim 1.

The use of two encodings guarantees a particularly high degree of security against inadmissible manipulation of the key switch.

It proves to be advantageous if the first excitation device is designed as a yoke wound around the one coil. This represents a particularly simple realization of the first excitation device.

Furthermore, it proves to be advantageous if the coil is designed as a planar coil. The realization of the coil as a planar coil represents a particularly easy to manufacture way of realization of the coil.

Furthermore, it proves to be advantageous if the first coding and of an electrically conductive and / or magnetizable material. An electrically conductive and / or magnetizable material influences the alternating magnetic field well.

Furthermore, it proves to be advantageous if the first coding as binary coding, bar coding, multilevel coding or is designed as an analog coding, since these codes are easy to implement.

Furthermore, it proves to be advantageous if the second coding is designed as analog coding. As a result, a particularly high level of security against manipulation of the key switch is achieved.

Furthermore, it proves to be advantageous if the key switch has a front plate with an opening for insertion of the key, wherein on the inside of the key switch, a non-electrically conductive and non-magnetizable separator is disposed at the opening, which spatially separates the opening of the first exciter , As a result, the ingress of dirt in the key switch and by the key switch in the interior of the control device is reliably prevented.

Furthermore, it proves to be advantageous if the key switch has a front plate with an opening for inserting the key, wherein on the inside of the key switch, a non-electrically conductive and non-magnetisable separating element is arranged at the opening which the opening of the first and the second Separates excitation device spatially. As a result, the ingress of dirt in the key switch and by the key switch in the interior of the control device is reliably prevented.

Furthermore, it proves to be advantageous if the key switch has a plurality of access codes, wherein the key switch in accordance with an access code with the read first and / or second coding depending on the access code outputs a respective access code associated access signal. As a result, e.g. with a key which a normal user possesses, only standard applications are unlocked, while with another key, which has only one skilled in the art, e.g. More dangerous operations can be unlocked, which may only be performed by qualified personnel.

Furthermore, it proves to be advantageous to provide an operating device for operating a machine and / or plant from automation technology, wherein the operating device has a key switch according to the invention. As a result, a dirt-sensitive control device is created

FIG 1

eine Bedieneinrichtung mit einem aus dem Stand der Technik bekannten mechanischen Schlüsselschalter,

FIG 2

die Codierung wird seriell vom Schlüsselschalter während des Einführvorgangs des Schlüssels ausgelesen,

FIG 3

ein Trennelement zum Abtrennen der Elektronik des Schlüsselschalters von der Öffnung des Schlüsselschalters,

FIG 4

ein Schlüssel mit einer Multilevelcodierung,

FIG 5

eine Auswerteeinheit zum Auswerten einer Multilevelcodierung,

FIG 6

ein Beispiel zum parallelen Auslesen eines Schlüssels mit einer Binärcodierung,

FIG 7

eine Auswerteeinheit zum parallelen Auswerten einer Codierung,

FIG 8

Ein Schlüssel mit zwei Codierungen,

FIG 9

eine Auswerteeinheit für einen Schlüssel mit zwei Codierungen,

FIG 10

einen Schlüssel mit einer Barcodierung, und

FIG 11

einen Schlüssel bei dem die Codierung mit einer lichtundurchlässigen Schicht abgedeckt ist.

Several embodiments of the invention are illustrated in the drawing and are explained in more detail below. Showing:

FIG. 1

an operating device with a mechanical key switch known from the prior art,

FIG. 2

the coding is read out serially by the key switch during the insertion process of the key,

FIG. 3

a separating element for disconnecting the electronics of the key switch from the opening of the key switch,

FIG. 4

a key with multilevel coding,

FIG. 5

an evaluation unit for evaluating a multilevel coding,

FIG. 6

an example for parallel reading of a key with a binary coding,

FIG. 7

an evaluation unit for the parallel evaluation of a coding,

FIG. 8

A key with two codes,

FIG. 9

an evaluation unit for a key with two codes,

FIG. 10

a key with a barcode, and

FIG. 11

a key in which the coding is covered with an opaque layer.

• L: Induktivität
• f: Frequenz des Wechselstroms

ein Wechselstrom I durch die Planarspule 4 fliest. Die Planarspule 4 erzeugt folglich zusammen mit dem Joch 3 ein magnetisches Wechselfeld B, d.h. ein sich zeitlich veränderndes Magnetfeld.In FIG. 2 are shown in the form of a schematic representation, essentially the electrical components of a key switch. The key switch has a first excitation device 6 which generates a first alternating magnetic field B and has a first inductance L of, for example, a few millihenri. The excitation device 6 consists of a coil which is formed in the embodiment as a planar coil 4 and a preferably horseshoe-shaped yoke 3, which consists of ferrite in the context of the embodiment. The excitation means 6, ie the planar coil 4 together with the yoke 3, have, as already mentioned above, a first inductance L. The planar coil 4 is mounted on a printed circuit board 5 together with an evaluation unit 10 arranged. The evaluation unit 10 generates an alternating voltage U _r , whereby according to the relationship $$I=\frac{{\mathrm{<figure-callout\; id="2"\; label="U\; r"\; filenames="imgf0001.png"\; state="\{\{state\}\}">U\; </figure-callout>}}_r}{2\mathit{\pi fL}}$$

• L: inductance
• f: frequency of the alternating current

an alternating current I through the planar coil 4 fliest. The planar coil 4 consequently generates, together with the yoke 3, an alternating magnetic field B, ie a time-varying magnetic field.

In FIG. 2 above, a key 7 associated with the key switch is shown. The key 7 consists of a non-conductive and non-magnetizable carrier element 8, on which a first coding 9 made of an electrically conductive and / or magnetizable material is attached. During an insertion of the key into the key switch, which is represented by an arrow 12, the first coding 9 is read out serially by the key switch, by means of the first magnetic field B, the first code 9 attached to the key 7, by means of the first alternating magnetic field B, is scanned. The first coding 9 is shown in FIG FIG. 2 from top to bottom through the yoke 3 and thus performed by the magnetic alternating field B. The first coding 9 effects a change of the first inductance L of the first excitation device 6, as a result of which the first coding 9 is read out by the key switch. As already mentioned, the first coding 9 causes a change in the inductance L of the excitation device 6, as a result of which the current I changes, which is evaluated by the evaluation device 10. For this purpose, the evaluation unit 10 measures the alternating current I which, as already mentioned, changes according to the first coding when the key is inserted into the key switch. In the context of the first exemplary embodiment, the first coding 9 is embodied as multilevel coding.

While in FIG. 2 Essentially the electronics of the key switch are shown in FIG. 3 essentially the passive components of the key switch shown. The key switch, has a front panel 11 which has an opening 14 for the introduction of the key 7. When inserting the key 7, the key is passed through the opening 14, which is represented by an arrow 12. On the inside of the key switch, the key switch on a non-electrically conductive and non-magnetizable separator 13 which is disposed at the opening and the key from the first exciter spatially completely separate. The partition member 13 is formed in the embodiment as a cuboid hollow body whose cavity is open only upwards in the direction of the opening 14. Thus, the partition 13 forms a blind hole through which no dirt entering through the opening 14 continues to the electronics, which in FIG. 2 is shown, the key switch can penetrate. The separating element 14 preferably separates the opening 14 airtight from the excitation device 6. The separating element 13 is arranged guided through the horseshoe-shaped yoke 3.

In FIG. 4 is a key 7 with a first coding 9, which is designed as multilevel coding, shown in detail. In contrast to a binary coding, a multilevel coding has a plurality of stages which are evaluated when they are exceeded by the evaluation unit 10. In the context of the embodiment, these are the four stages reset, clock, data and ready, which a certain amount of in FIG. 4 correspond to peg-shaped design of the first coding 9.

In FIG. 5 the evaluation unit belonging to the multilevel coding is shown in detail. The evaluation unit 10 in this case has an excitation unit 16 which generates the alternating voltage U _r . As already stated above, an alternating current I is produced by the planar coil 4. The first excitation device 6 has an inductance L of several milihenri, which changes when carrying out the first coding 9 by the magnetic field B (The changing inductance L is in FIG. 5 symbolically represented by a black rectangle with an oblique arrow). As a result, the alternating current I, which is measured by the excitation unit 16, changes accordingly. The first coding 9 is thus sampled inductively by means of the alternating magnetic field B. The excitation unit 16 generates on the output side in accordance with the changing current I and thus according to the changing inductance L a correspondingly changing output voltage U (L). The output voltage U (L) is compared via comparators 17, 18, 19 and 20 with different voltages U1, U2, U3 and U4. If the voltage U (L) exceeds the voltage U1, the signal ready is set to logic "1", the voltage U (L) exceeds the voltage U2, the signal data is set to logic "1", the voltage U exceeds L) the voltage U3, the signal clock is set to logic "1" and exceeds the voltage U (L), the voltage U4, the signal reset is set to logic "1".

If no key is inserted, the reset signal clears the flip-flops 25-29, which form a shift register. When inserting the key according to FIG. 4 The first tooth b0 of the key 7 via the signal data to set the flip-flop 34. The tooth back edge leads to a falling edge of the signal clock, resulting in the transfer of the data bit from flip-flop 34 in the flip-flop 25 of the shift register and to clear the flip-flop 34 leads. The next tooth b1 of the key does not lead to the setting of the flip-flop 34, so that at the next tooth trailing edge a zero is taken over into the flip-flop 25 of the shift register, at the same time b0 in the shift register from flip-flop 25 to flip-flop Flop 26 pushed further.

If the key is fully inserted, the rising edge of the ready signal will cause the code checker 31 to clear. If all the bits read in are in the shift register have the correct value, the output Z of the code verifier 31 is set to logical "1" and thus the validity of the key is reported.

As soon as the key is even pulled out a little, the falling edge of the signal ready leads to the setting of the flip-flop 30, which blocks the code check. Only after completely removing the key does the reset signal clear the blocking flip-flop 30 again.

In FIG. 6 an example is shown which allows a parallel read out of the first coding. Unlike the in FIG. 2 shown serial readout of the first coding, in which only a single excitation means 6 is required, several first excitation means are required in parallel readout. In the context of the embodiment, the key switch has in FIG. 6 the three first excitation means 6a, 6b and 6c with the respectively associated planar coils 4a, 4b and 4c and the respectively associated yokes 3a, 3b and 3c. The operation with respect to each first initiator is identical to the in FIG. 2 illustrated and described first excitation means 6, the evaluation unit 10 evaluates the analog of the height of the currents I ₁ and I ₂ and I ₃ , which in detail in FIG. 7 is described. In FIG. 6 Above a key 7 is further shown on the support member 8, a first coding 9 is attached, wherein the first coding is formed as a binary coding. For this purpose, the first coding 9 has either an electrically conductive and / or magnetizable region at the positions at which the first excitation devices later scan the key, or no such region is provided at the relevant point, which is shown in FIG FIG. 6 shown in dashed lines. An attached area corresponds, for example, to a logical "1", while a non-attached area corresponds, for example, to a logical "0" or vice versa.

In FIG. 7 the evaluation unit 10 belonging to the parallel readout is shown. In this case, the first excitation device 6a has the inductance L ₁ , the first excitation device 6b has the inductance L ₂ , and the first excitation device 6c has the inductance L ₃ . The inductances L ₁ , L ₂ and L ₃ then change again according to the first coding 9 of the key 7. The excitation unit 16 generates the alternating voltages U _r1 , U _r2 and U _r3 , so that, corresponding to the changing inductances L ₁ , L ₂ and L ₃ change the alternating currents I ₁ , I ₂ and I ₃ , which is evaluated in the excitation unit 16. The excitation unit 16 then generates, according to the changing inductances L _1, L ₂ and L ₃ to the inductances L _1, L ₂ and L respectively associated _three voltages U ₁ (L _1), U ₂ (L ₂₎ and U ₃ (L ₃ ), which are supplied to a comparator 24 as an input. The comparator 24 then compares the three voltages U ₁ (L ₁ ), U ₂ (L ₂ ) and U ₃ (L ₃ ) with an internal reference voltage, for example, when the reference voltage is exceeded, a logical "1" or alternatively a logical "0 " is produced. Each of the three voltages U ₁ (L ₁ ), U ₂ (L ₂ ) and U ₃ (L ₃ ) is thus compared with the internal reference voltage and generates the binary output signals b0, b1 and b2 in parallel. These are fed to a comparator 25 as input, which compares them with the binary numbers c0, c1 and c2, which represent the access code within the scope of the exemplary embodiment. If they match, an access signal Z is set to logic "1" by the comparator 25 on the output side, and thus the key is recognized as suitable. The access signal Z can subsequently be used, for example, to control a relay or, for example, be read directly from an operating device and / or a controller and / or a control device.

In FIG. 8 the invention is shown, in which two codes are read in simultaneously.

On the carrier element 8 of the key 7 is a first coding 9 and a second coding 9 'on both sides attached to the key. The first coding 9 and the second coding 9 'are formed in the context of the embodiment as analog codings. The first coding 9 is designed to detect the instantaneous position of the key in the key switch during the insertion of the key as a location track, while the second coding 9 'is in the form of any curve. From the operation corresponds to the embodiment according to FIG. 8 the embodiment according to FIG. 2 However, in contrast to the embodiment according to FIG FIG. 2 a second excitation means 6 'with a second planar coil 4' and a second yoke 3 'is present. The first coding 9 and the second coding 9 'are read out at the same time, it being recognized by means of the first coding 9 during insertion of the key into the key switch at which position the key is currently located and thus the second coding 9' can be correspondingly evaluated , The first coding 9 contains the information of the bit number, while the second coding 9 'contains the associated bit value.

Otherwise, the functionality that already in FIG. 2 The evaluation unit 10 simultaneously processes the alternating currents I and I 'from the first excitation device 6 and the second excitation device 6'.

In FIG. 9 is the invention according to FIG. 8 associated evaluation unit 10 shown schematically. The first excitation device 6 has the inductance L that changes when the key is inserted, while the second excitation device 6 'has the variable inductance L' when the key is inserted. Analogous to the preceding examples already described, the excitation unit 16 generates the two voltages U _r and U _r ', whereby the two alternating currents I and I' are produced by the respectively associated planar coil 4 and 4 '. On the output side, the excitation unit 16 generates by evaluating the inductances L and L 'changed upon insertion of the key in accordance with FIG alternating currents I and I 'changed, the voltages U (L) and U (L') ', the voltage U (L) representing the first coding 9, while the output voltage U (L') 'representing the second coding 9' , The two voltages U (L) and U (L ')' are evaluated by a decoder 32, which reads in the voltages U (L) and U (L ')' and links the two voltages together, the first coding Number (location information) while the second encoding provides the bit number associated with the bit value. The decoder 32 can thus extract the bit number from the first coding 9, while it can extract the associated bit value from the second coding 9 '. On the output side, the decoder 32 outputs the corresponding bits b0, b1 and b2 thus determined, which are then compared by means of the comparator 25 with the access code c0, c1 and c2, which are in the form of individual bits, for example. If they match, the access signal Z is set to logic "1" by the comparator 25. The first coding 9 and the second coding 9 'are preferably evaluated in a quantized manner, ie if, for example, the second coding 9' exceeds a certain height at a position, a logic "1" is recognized and if a certain height is undershot, a value is selected logical "0" or vice versa detected.

In FIG. 10 a key 7 is shown in which on the support member 8, a first coding 9 is attached in the form of a bar code. An evaluation of the barcode can be done eg by means of in FIG. 2 and FIG. 5 However, the output voltage of the excitation unit 16 output voltage U (L) is evaluated by a downstream bar decoder that decodes the bar code, and then compared the thus decoded bar code by means of a comparator with the access code becomes. If they match, then the access signal Z at the output of the comparator is again set to logic "1".

In FIG. 11 schematically illustrates a key that can be applied to all of the previously described possible keys in all described coding. According to the key FIG. 11 According to the invention, the coding is covered with an opaque layer 33, so that the coding from the outside is no longer visually recognizable. As a result, a replica of the key is difficult. Otherwise, the key corresponds to FIG. 11 the keys described above. The same elements are therefore provided with the same reference numerals as in the preceding figures.

By key switch according to the invention can be realized a high degree of protection against contamination. Furthermore, the sampling of the coding is wear-free, which allows a long life of the key switch and the key. Furthermore, the key switch requires only little space. Since the key switch reads out the coding exclusively via an alternating magnetic field, it has a high immunity to electromagnetic interference, which is e.g. from radio transmission systems. Furthermore, the security against manipulation is very high. The key switch can be easily parameterized to different keys, for example by software. Furthermore, the key function can be combined with an electromechanical switching function.

Furthermore, different operator actions can be unlocked with different keys having different codes. Thus, for example, with a key which a normal user owns only standard applications can be unlocked, while with another key, which has only one expert more extensive, eg dangerous operations are enabled, which may be performed only by specialized personnel. For this purpose, the key switch can have, for example, a plurality of code checkers 31 and / or comparators 25 connected in parallel, for example, each check a different access code and output a respective access signal.

Claims (10)

1. Key-operated switch (2), the key-operated switch (2) having a first excitation device (6) which generates a first alternating magnetic field (B) and has a first inductance, the key-operated switch (2) being constructed in such a manner that the first alternating magnetic field (B) can be used to scan a first coding (9) of a key (7), the first coding (9) changing the first inductance of the first excitation device (6), and the first coding (9) being read by the key-operated switch (2) in this manner, the first excitation device (6) being used by the key-operated switch (2) to serially read the first coding (9) during the operation of inserting the key (7), the key-operated switch (2) having a second excitation device (6') which generates a second alternating magnetic field (B') and has a second inductance, the key-operated switch (2) being constructed in such a manner that the second alternating magnetic field (B') can be used to scan a second coding (9') of the key (7), the second coding (9') changing the second inductance of the second excitation device (6'), and the second coding (9') being read by the key-operated switch (2) in this manner, the first (19) and second (9') codings being read simultaneously, and the key-operated switch (2) using the first coding (9) to determine the position of the key (7) in the key-operated switch (2) during the operation of inserting the key (7).
2. Key-operated switch according to Claim 1, characterized in that the first excitation device (6) is in the form of a yoke (3), around which a coil (4) is wound.
3. Key-operated switch according to Claim 2, characterized in that the coil (4) is in the form of a planar coil.
4. Key-operated switch (2) according to one of the preceding claims, characterized in that the first coding (9) is made of an electrically conductive and/or magnetizable material.
5. Key-operated switch (2) according to one of the preceding claims, characterized in that the first coding (9) is in the form of binary coding, bar coding, multilevel coding or analog coding.
6. Key-operated switch (2) according to one of the preceding claims, characterized in that the second coding (9') is in the form of analog coding.
7. Key-operated switch (2) according to one of the preceding claims, characterized in that the key-operated switch (2) has a front panel (11) having an opening (14) for inserting the key (7), a separating element (13) which is not electrically conductive and is not magnetizable being arranged at the opening (14) on the inside of the key-operated switch (2) and physically separating the opening (14) from the first excitation device (6).
8. Key-operated switch (2) according to one of Claims 2 to 7, characterized in that the key-operated switch (2) has a front panel (11) having an opening (14) for inserting the key (7), a separating element (13) which is not electrically conductive and is not magnetizable being arranged at the opening (14) on the inside of the key-operated switch (2) and physically separating the opening (14) from the first and second excitation devices (6, 6').
9. Key-operated switch (2) according to one of the preceding claims, characterized in that the key-operated switch (2) has a plurality of access codes, in which case, when an access code matches the first and/or second coding(s) which has/have been read, the key-operated switch (2) outputs an access signal associated with the respective access code on the basis of the access code.
10. Operating device (1) for operating a machine and/or a system from automation technology, the operating device having a key-operated switch (2) according to one of Claims 1 to 9.

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