DE102020212536A1 - Button for security applications - Google Patents

Abstract

The invention relates to a button for security applications and a method for evaluating signals from such a button. The button (1) comprises an operating surface (20), a first touch-sensitive sensor (2), a first evaluation unit (6) electrically connected to the first touch-sensitive sensor (2), a first contact (6) electrically connected to the first evaluation unit (6). 8), a second touch-sensitive sensor (3), a second evaluation unit (7) electrically connected to the second touch-sensitive sensor (3), and a second contact (9) electrically connected to the second evaluation unit (7), the first touch-sensitive sensor ( 2) and the second touch-sensitive sensor (3) use different technologies, the first touch-sensitive sensor (2) and the second touch-sensitive sensor (3) being arranged in such a way that touching the operating surface (20) and/or applying force to the operating surface (20) with a human finger (4) or an input element by means of the first touch-sensitive sensor (2) and by means of the second ber guidance-sensitive sensor (3) can be detected at the same time, and wherein the first evaluation unit (6) and the second evaluation unit (7) are electrically connected for error detection.

Description

FIELD OF APPLICATION AND PRIOR ART

The invention relates to a button for security applications and a method for evaluating signals from such a button.

In the context of the application, a button is a control element that can be actuated mechanically or manually by touching or pressing. Depending on the application, the button is designed as a pushbutton switch, in particular as a normally open or normally closed contact, which automatically returns to an initial state after there is no contact or applied force, or as a changeover switch, which remains in a changed switching state after being actuated.

It is known for security applications to implement relays, pushbutton switches and/or changeover switches with two or more electromechanical contacts. In order to avoid a risk of erroneous tripping due to a defect in a contact, for example failure to open due to so-called welding of a contact, the contacts are mechanically coupled. Such mechanically coupled contacts are also referred to as forcibly guided contacts.

Because of their electromechanical structure, such buttons with positively driven contacts require a relatively large amount of space and often have a limited maximum number of switching cycles. In order to detect the failure of a contact, the contacts must also be monitored and diagnosed with redundantly designed buttons.

TASK AND SOLUTION

It is an object of the invention to create a small button for security applications. A further object of the invention is to provide a method for evaluating signals from a button of this type.

According to a first aspect, a button comprising an operating surface, a first touch-sensitive sensor, a first evaluation unit electrically connected to the first touch-sensitive sensor, a first contact electrically connected to the first evaluation unit, a second touch-sensitive sensor, a second touch-sensitive sensor electrically connected connected second evaluation unit and a second contact electrically connected to the second evaluation unit, wherein the first touch-sensitive sensor and the second touch-sensitive sensor use different technologies, wherein the first touch-sensitive sensor and the second touch-sensitive sensor are arranged in such a way that touching the control surface and/or or a force input on the operating surface with a human finger or an input element by means of the first touch-sensitive sensor and by means of the second touch-sensitive sensor at the same time can be detected, and wherein the first evaluation unit and the second evaluation unit are electrically connected for error detection.

The terms "a", "an" etc. are used in connection with the application only as indefinite articles and not as measure words. The terms "first", "second", etc. are used only to distinguish between elements and do not indicate a hierarchy of elements.

In connection with the application, electronic systems for detecting a touch of the operating surface and/or a force input on the operating surface with a human finger or an input element are referred to as touch-sensitive sensors. Such sensors are also referred to as touch sensors.

Various technologies are known for detecting a touch and/or a force input. In one embodiment, the sensors are designed as force sensors, by means of which forces acting on the operating surface can be detected. In one embodiment, the acting forces bring about a movement of the operating surface. In other configurations, the sensors are suitable for detecting a touch on the control surface even without forces acting on it for an adjustment movement. At least two different technologies are used in the pushbutton according to the invention. In this context, diverse technologies with different physical principles are referred to as different technologies. The use of different technologies reduces the risk of the sensors failing at the same time.

Electronic units are referred to as evaluation units within the meaning of the application, which are suitable for receiving a signal from a sensor, processing it and, based on a result of the processing, generating an output signal which is provided at the contact electrically connected thereto. By using electronic units, which are electrically connected for error detection, instead of electromechanical components for positively guiding contacts, a small pushbutton can be implemented.

In one embodiment, the button is designed as a button switch, ie as an element which automatically returns to an initial state when an acting force is removed.

In one configuration, the first touch-sensitive sensor and the second touch-sensitive sensor are selected from the group comprising a piezoelectric sensor, a capacitive sensor and a resistive sensor. In one embodiment, the button includes a piezoelectric sensor and a capacitive sensor in order to use different technologies to detect a force acting on the operating surface when a finger or an input element is pressed. The sensors are selected in such a way that a large number of possible switching cycles can be implemented.

In one embodiment, the first touch-sensitive sensor and the second touch-sensitive sensor each have a flat structure and are aligned parallel to a plane of the control surface, with the first touch-sensitive sensor covering the second touch-sensitive sensor at least in the area of the control surface. The flat design makes it possible to create a button that is flat in the operating direction. The overlapping arrangement allows simultaneous detection of a touch on the operating surface and/or a force acting on the operating surface.

In one embodiment, the control surface is an integral part of the first touch-sensitive sensor and/or the second touch-sensitive sensor. In one embodiment, the first sensor is a capacitive sensor. Depending on the design, the capacitive sensor can be used to detect an acting force, a force-free touch or an approach. In one configuration, the capacitive sensor comprises a measuring electrode, with the operating surface being movable relative to the measuring electrode, so that a distance between the measuring electrode and the operating surface and thus an electrically measurable capacitance change. Alternatively or additionally, the second sensor in one configuration is a piezoelectric sensor with a piezoelectric layer, with a force acting on the operating surface causing a deformation of the piezoelectric layer.

In one configuration, the first touch-sensitive sensor and the second touch-sensitive sensor are arranged on a common circuit board. In one embodiment, the evaluation units are also implemented on this printed circuit board.

In one configuration, the first evaluation unit and the second evaluation unit are electrically connected bidirectionally for error detection by means of cross-comparison. In one embodiment, it is provided for a cross-comparison that the first evaluation unit cyclically sends an input signal to the second evaluation unit and the second evaluation unit cyclically sends an input signal to the first evaluation unit. The input signals can be compared with one another in the evaluation units. Such a cross-comparison can thus be used by each evaluation unit to determine whether the two sensors have the same states and the corresponding evaluation unit is therefore functional. The bidirectional electrical connection makes it possible to implement redundant operation in accordance with category 3 or 4 of "DIN EN IS013849 - Safety of machines - Safety-related parts of controls".

In one embodiment, the first evaluation unit and the second evaluation unit are designed to apply a first output signal with two optionally present states to the first contact or to apply a second output signal with two optionally present states to the second contact and, when the control surface and/or or a force input on the operating surface, which is detected by means of the first touch-sensitive sensor and by means of the second touch-sensitive sensor, to change a state of the first output signal and a state of the second output signal. A touch of the control surface detected by the sensors and/or a force input on the control surface detected by the sensors cause corresponding input signals, which are fed to the evaluation units. In one configuration, a change in the state of both output signals takes place only during error-free operation, i.e. when the sensors deliver correlating input signals. In other configurations, a state change of both output signals after evaluation of the input signals of the sensors is also provided when the sensors supply contradictory input signals, but it can be assumed that the button has been actuated due to an error detection that has been carried out. This is expedient in particular for safety applications in which a failure of a sensor must not lead to a loss of a safety function. Output signals with exactly two states are also referred to as binary output signals. On the output signals, especially on binary output signals. In one embodiment, additional information can be modulated, for example to allow error signalling. The binary values of the output signals are referred to as 0 and 1 in the context of the application.

In an advantageous embodiment, the first evaluation unit and the second evaluation unit are designed to apply output signals with opposite states to the first contact and the second contact when the button is operating properly. If irregular operation of the button is detected, output signals with matching states can be applied to the contacts in one embodiment, in order to clearly signal an irregular operation of the button to a connected system.

According to a second aspect, a button panel for a security device is created comprising a plurality of buttons designed as buttons.

According to a third aspect, a method for operating a button is created, with output signals present at the first contact and at the second contact being evaluated using a truth table.

In one embodiment, a first output signal with two optional states is applied to the first contact and a second output signal with two optional states is applied to the second contact, with the first touch-sensitive sensor being activated when the operating surface is touched and/or when a force is detected the control surface sends a first input signal to the first evaluation unit, and the second touch-sensitive sensor sends a second input signal to the second evaluation unit when a touch is detected on the control surface and/or a detected force input on the control surface, with the first input signal and the second input signal correlating , a state of the first output signal and a state of the second output signal can be changed.

In one embodiment, when the button is operating properly, output signals with opposite states are applied to the first contact and the second contact. In one embodiment, binary output signals are provided, with, for example, an output signal of 0 being present on the first contact and an output signal of 1 being present on the second contact without touching the operating surface of the button, and an output signal 1 being present on the first contact and an output signal 1 on the second contact when touched an output signal of 0 is present.

character list

• 1: einen Taster mit zwei berührungssensitiven Sensoren;
• 2: einen logischen Aufbau des Tasters gemäß 1; und
• 3: eine Wahrheitstabelle zur Auswertung von Ausgangssignalen des Tasters gemäß 1.

Further advantages and aspects of the invention result from the claims and from the following description of an exemplary embodiment of the invention. The schematic figures show:

• 1 : a button with two touch-sensitive sensors;
• 2 : according to a logical structure of the button 1 ; and
• 3 : a truth table for evaluating the output signals of the button according to 1 .

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

1 and 2 show schematically a mechanical structure or a logical structure of a button 1 comprising a first touch-sensitive sensor 2 and a second touch-sensitive sensor 3.

The button 1 shown also includes a control surface 20 which is an integral part of the first touch-sensitive sensor 2 in the illustrated embodiment. The button 1 can be actuated by a human finger 4 by touching the operating surface 20 or by applying a force to the operating surface 20 in an operating direction I represented by an arrow.

In the exemplary embodiment shown, the sensors 2 , 3 each have a flat structure and are aligned parallel to a plane of the operating surface 20 . The first touch-sensitive sensor 2 having the operating surface 20 is arranged in front of the second touch-sensitive sensor 3 in the operating direction I, with the first sensor 2 covering the second sensor 3 in the area of the operating surface 20 . The touch-sensitive sensors 2, 3 are designed such that the touch of the operating surface 20 with the finger 4 or an input element, not shown, can be detected simultaneously by means of the first touch-sensitive sensor 2 and by means of the second touch-sensitive sensor 3.

The sensors 2, 3 are both arranged on a front side of a circuit board 5 in the illustrated embodiment. A first evaluation unit 6 and a second evaluation unit 7 are provided on a rear side of the printed circuit board 5 . As schematic in 2 shown, the first touch-sensitive sensor 2 is electrically connected to the first evaluation unit 6 and the second touch-sensitive sensor 3 is electrically connected to the second evaluation unit 7. In addition, the exemplary embodiment provides for the first evaluation unit 6 and the second evaluation unit 7 to be connected to one another for error detection are. In one embodiment, the connection is a bidirectional connection for a cross-comparison.

For a cross comparison, the first evaluation unit 6 cyclically sends an input signal to the second evaluation unit 7 and the second evaluation unit 7 cyclically sends an input signal to the first evaluation unit 5. In the evaluation units 6, 7, the input signals are compared with one another. Such a cross-comparison can thus be used by each evaluation unit 6, 7 to determine whether the two sensors 2, 3 have the same states and the corresponding evaluation unit is therefore functional. This makes it possible to implement redundant operation according to category 3 or 4 of "DIN EN IS013849 - Safety of machines - Safety-related parts of controls".

The first evaluation unit 6 is electrically connected to a first contact 8 and designed to apply a binary output signal with the states 0, 1 to the first contact 8 .

The second evaluation unit 7 is electrically connected to a second contact 9 and designed to apply a binary output signal with the states 0, 1 to the second contact 9 .

In the exemplary embodiment shown, the first contact 8 and the second contact 9 are also bidirectionally coupled to the first evaluation unit 6 and the second evaluation unit 7 for monitoring with at least adequate error detection.

As in 1 shown, the first sensor 2, the second sensor 3, the first evaluation unit 6, the second evaluation unit 7, the first contact 8 and the second contact 9 are housed in a housing 10.

The first evaluation unit 6 is designed to apply a first output signal with two optionally present states 0 and 1 to the first contact 8 and to change a state of the first output signal when the operating surface 20 is touched.

Likewise, the second evaluation unit 7 is designed to apply a first output signal with two optionally present states 0 and 1 to the second contact and to change a state of the second output signal when the operating surface 20 is touched.

The first evaluation unit 6 and the second evaluation unit 7 are designed in such a way that when the button 1 is operating properly, output signals with opposite states are applied to the first contact 8 and the second contact 9 .

3 shows a truth table for evaluating the signals of a button 1 designed as a button according to FIG 1 and 2 with the first input signal S1 of the first sensor 2, the second input signal S2 of the second sensor 3 and the output signals 01, 02, which are applied to the first contact 8 and the second contact 9 by means of the evaluation units 7, 7.

For the input signals S2, S2 of the sensors 2, 3, a distinction is made between an “ON” state when the control surface 20 is touched or a force applied to the control surface and an “OFF” state without touching or force applied to the control surface 20 in regular operation.

The first evaluation unit 6 is designed in such a way that a first output signal 01 with the state 0 and with an input signal S1 of the first sensor 2 with the state “OFF” are sent to the first contact 8 when the input signal S1 of the first sensor 2 is in the “OFF” state. AN" to apply a first output signal 01 with the status 1.

The second evaluation unit 7, on the other hand, is designed in such a way to generate a second output signal O2 with the status 1 at the second contact 9 when the input signal S2 of the second sensor 3 has the status “OFF” and with the status 1 for an input signal S2 of the second sensor 3 with the status “ AN" to apply a second output signal O2 with the status 0.

A change in the first output signal 01 from the state 0 to the state 1 with a simultaneous change in the second output signal O2 from the state 1 to the state 0 thus signals with sufficient certainty a correct actuation of the button 1, detected by both sensors 2, 3 .

On the other hand, if only one of the sensors 2, 3 delivers an input signal S1 or S2 with the status “ON”, this indicates an irregular status of the button 1, as shown in the truth table 3 marked by X. The irregular state can be signaled by output signals 01, 02 with the same state 0 or 1. It is conceivable, for example, to also trigger a safety function through matching output signals O1, O2 with the state 1, with an error display being possible at the same time due to the output signal O2 deviating from regular operation. Alternatively, depending on the requirement and/or based on a diagnosis of the input signals S1, S2 at the contacts 8, 9 carried out by means of the button 1, output signals 01, 02 can be the same as those of a detected regular actuation of button 1 can be applied in order to cause a safety function associated with button 1 to be executed.

Claims (10)

Button for security applications, comprising an operating surface (20), a first touch-sensitive sensor (2), a first evaluation unit (6) electrically connected to the first touch-sensitive sensor (2), and a first contact (8) electrically connected to the first evaluation unit (6). , characterized in that a second touch-sensitive sensor (3), a second evaluation unit (7) electrically connected to the second touch-sensitive sensor (3) and a second contact (9) electrically connected to the second evaluation unit (7) are provided, the first touch-sensitive sensor (2) and the second touch-sensitive sensor (3) use different technologies, the first touch-sensitive sensor (2) and the second touch-sensitive sensor (3) being arranged in such a way that touching the control surface (20) and/or a Force entry on the operating surface (20) with a human finger (4) or an input element using the e First touch-sensitive sensor (2) and by means of the second touch-sensitive sensor (3) can be detected simultaneously, and wherein the first evaluation unit (6) and the second evaluation unit (7) are electrically connected for error detection. button after claim 1 , characterized in that the first touch-sensitive sensor (2) and the second touch-sensitive sensor (3) are selected from a group comprising a piezoelectric sensor, capacitive sensor and a resistive sensor. button after claim 1 or 2 , characterized in that the first touch-sensitive sensor (2) and the second touch-sensitive sensor (3) have a planar structure and are aligned parallel to a plane of the operating surface (20), the first touch-sensitive sensor (2) the second touch-sensitive sensor ( 3) covered at least in the area of the operating surface (20). button after claim 1 , 2 or 3 , characterized in that the operating surface (20) is designed integrally with the first touch-sensitive sensor (2) and/or with the second touch-sensitive sensor (30). button after one of the Claims 1 until 4 , characterized in that the first touch-sensitive sensor (2) and the second touch-sensitive sensor (3) are arranged on a common circuit board (5). button after one of the Claims 1 until 5 , characterized in that the first evaluation unit (6) and the second evaluation unit (7) are bidirectionally electrically connected for error detection by means of cross-comparison. button after one of the Claims 1 until 6 , characterized in that the first evaluation unit (6) and the second evaluation unit (7) are designed to at the first contact (8) a first output signal (01) with two optionally present states (0, 1) or at the second Contact (9) to apply a second output signal (O2) with two optionally present states (0, 1) and to touch the control surface (20) and/or force input on the control surface (20), which or which by means of the first touch-sensitive sensor (2) and by means of the second touch-sensitive sensor (3) is detected to change a state of the first output signal (01) and a state of the second output signal (O2), wherein preferably the first evaluation unit (6) and the second evaluation unit ( 7) are designed to apply output signals (O1, O2) with opposite states to the first contact (8) and the second contact (9) when the button (1) is operating properly. Keypad for a safety device comprising a plurality of buttons according to one of Claims 1 until 7 . Method for operating a button according to one of Claims 1 until 7 , characterized in that input signals (S1, S2) detected by means of the first and the second touch-sensitive sensor (2, 3) are evaluated by means of a truth table. procedure after claim 9 , characterized in that at the first contact (8) a first output signal (01) with two optionally present states (0, 1) and at the second contact (9) a second output signal with two optionally present states (0, 1) is applied, and the first touch-sensitive sensor (2) sends a first input signal (S1) to the first evaluation unit (6) when a touch is detected on the operating surface (20) and/or a detected force is applied to the operating surface (20), and the second touch-sensitive sensor (3) transmits a second input signal (S2) to the second evaluation unit (6) when a touch is detected on the operating surface (20) and/or a detected force is applied to the operating surface (20), wherein if the first input signal (S1) and the second input signal (S2) correlate, a state of the first output signal (01) and a state of the second output signal (O2) are changed, preferably with proper operation of the button (1) on the first contact (8) and the second contact (9) Output signals (01, O2) are applied with opposite states.

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