EP2826146A1

EP2826146A1 - Proximity sensor and operator control panel formed therewith

Info

Publication number: EP2826146A1
Application number: EP13703000.3A
Authority: EP
Inventors: Markus TOESKO; Alexander Graf
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2012-03-14
Filing date: 2013-02-01
Publication date: 2015-01-21
Also published as: WO2013135428A1; US20150014299A1; DE102012203954A1

Abstract

The invention relates to a proximity sensor (1), in particular for use with a control panel (14), preferably a cooktop, wherein the proximity sensor (1) is provided with at least one antenna (3), a frequency generator (2), and a power detector (7). The at least one antenna (3) is coupled to the frequency generator (2) in order to supply the former with power, wherein the power detector (7) is provided to detect a power at the at least one antenna (3), which varies subject to the radiated power, and wherein the power detector (7) is further provided to emit a signal (A) in accordance with the detected power.

Description

Proximity sensor and thus formed control panel

The present invention relates to a proximity sensor according to the preamble of claim 1. Furthermore, the invention relates to a control panel formed with the proximity sensor according to the preamble of claim 8, in particular for a cooktop.

In the prior art, different sensor arrangements are known for use with control panels, in particular in hobs. From the publication

DE 10 2010 007 620 A1, for example, an inductive proximity sensor is known which makes use of transmitting and receiving coils with a phase shift determined thereon, from the document DE 20 2006 003 1 15 U1 a sensor which acts capacitive and their activation by pressing on the Control panel, from the document DE 10 2006 052 875 a sensor, which is formed with infrared sensor elements.

However, these known sensor arrangements pose problems when used in cooktops. An inductive sensor is unintentionally influenced by metal structures, e.g. through the metal housing of a hob, the capacitive sensors u.a. by water or steam on the hob and the infrared sensors e.g. through the glass surface of a hob, in particular by varying the color of the same.

Proceeding from this, the present invention has for its object to provide a sensor and a thus bildbares control panel, which overcome these disadvantages and in particular are inexpensive to implement.

This object is achieved by the features of claim 1 and claim 8. Advantageous embodiments and further developments are the subject of the dependent claims.

According to the invention, a proximity sensor is proposed, in particular for use with a control panel, preferably an electrical appliance, furthermore, in particular, a cooktop. By means of the proximity sensor is advantageously a contact Loose triggering a switching operation allows, wherein the proximity sensor can also be advantageously operated without moving parts, ie so far wear.

The proximity sensor according to the invention has at least one antenna, a frequency generator and a power detector. Here, the at least one antenna is coupled to its supply to the frequency generator, in particular via a feed-in point, preferably a base point of the antenna. A trailing wave can be guided from the frequency generator via a line and preferably a coupling element to the antenna.

It is preferred that the frequency generator continuously energize or power the antenna during operation of the proximity sensor or, e.g. when using multiple antennas, especially at intervals. Further preferably, the frequency generator feeds or excites the respective antenna on a discrete frequency, in particular all antennas on a single discrete frequency. Such a frequency corresponds in particular to the operating frequency of the proximity sensor. A respective antenna is furthermore fed in particular in each case or by means of a constant power or output power of the frequency generator.

Preferably, the respective antenna has a low bandwidth at the discrete frequency or operating frequency of the proximity sensor and also high quality.

In the context of the present invention, provision is also made in particular for the respective antenna to be impedance-matched to the frequency generator, wherein the antenna is preferably excited by the frequency generator with a low energy. This results in an advantageously low energy consumption during the operation of the sensor.

The frequency generator, whose terms in the present case also equivalent components are included, can be advantageously provided as an integrated component, ie as a chip, in particular in the form of a frequency synthesizer. An antenna, preferably according to the electrical principle, can be formed in a cost-effective and simple manner as a planar, in particular printed or punched antenna, preferably on a carrier substrate of the proximity sensor, which is for example in the form of a lead. terplatte is provided. In addition, of course, further embodiments of the antenna are conceivable, in particular also different geometries. If required, a shield can be provided between antennas and / or sensors.

In the case of the proximity sensor according to the invention, which in particular falls under the electromagnetic mode of action, the power detector is provided to determine a power at the at least one antenna or determines a power at the at least one antenna which varies as a function of the radiated power. For this purpose, the power detector may be suitably coupled to the antenna or electrically connected thereto.

Preferably, the power detector is coupled to the antenna via a coupling device or coupling element, e.g. via a directional coupler or a splitter. About such a coupling element, which is preferably designed to separate or decouple a returning wave portion of the running wave portion or coupled out, the power detector, a power which varies depending on the radiated power, advantageously determine exactly. This is because the determination can be based on the returning wave and no superposition with the outgoing wave makes it difficult to determine. The frequency generator can also be coupled to the antenna via the coupling element.

The power detector, whose terms in the present case also equivalent components are included, can also be inexpensively provided as an integrated component, wherein it is preferably provided the frequency generator, the at least one antenna and the power detector on a common carrier substrate in particular form a single circuit board to accommodate together with a respective coupling element. Thus, an extremely small-sized proximity sensor can be obtained.

The power detector is further provided to output or output a signal as a function of the determined power, which depends in particular on a radiated power. By means of the output signal, a switching process can be triggered, in particular by threshold value comparison, wherein the threshold values can define switching points. Provision is made in this case that the proximity sensor further comprises an evaluation device, in particular a μΟοηΐΓθΙΙβΓ, which is coupled to the power detector, in particular with this directly electrically connected, and which the signal of the power detector can be supplied. For example, the evaluation device can define or implement the threshold values upon reaching which a respective switching operation can be triggered by the evaluation device. A switching operation can be effected in a simple manner by correlating the signal output by the power detector with at least one of the defined switching thresholds.

Preferably, the evaluation device may alternatively or additionally be designed to correlate signal patterns or characteristics with one another, in particular to a correlation of the power detector signal with at least one stored signal pattern. Here, predetermined signal characteristics, e.g. the signal duration, a signal swing, in particular over the time, the waveform or other signal properties, which define an intended approximation profile for the proximity sensor or its switching operation, be correlated with the power detector signal. In this way, a switching process can be triggered according to whether the intended approximation profile was detected in the course of the correlation.

In one embodiment of the invention, it is provided to form the proximity sensor with a plurality of antennas. Such a proximity sensor preferably comprises a multiplexer which may be e.g. is formed as an IC and via which a respective antenna is selectively coupled to the frequency generator or selectively the power of an antenna can be determined.

This advantageously makes it possible to control or interrogate a plurality of antennas by means of a single frequency generator or else a single power detector. In this case, the antennas are each supplied with an interval or their power varying as a function of the radiated power is interrogated at intervals, ie for the duration of the respective switching through of the multiplexer. Depending on the interval and the antenna, a signal can be output by the power detector and possibly a signal Switching signal to be generated by the evaluation unit. The multiplexer can preferably be controlled by the evaluation unit, ie via a signal connection.

Preferably, the multiplexer and / or the evaluation unit may also be formed on a carrier substrate of the proximity sensor, in particular on a carrier substrate, preferably in the form of a printed circuit board on which the one or more antennas of the proximity sensor are arranged, for example, again as IC. Further preferably, it can be provided to form the frequency generator and the power detector, in particular in particular the evaluation unit and / or the multiplexer, as a one-piece IC or chip.

To be able to act as a proximity sensor, it is provided - as noted above - to excite the antenna each with a low energy at a discrete frequency. In particular, due to the antenna matching, the vast majority of the power is emitted in this case, so that the power detector coupled to the antenna, in particular via a coupling element as described above, measures only low power. An element carried in the electromagnetic field of the antenna, i. an interaction element, even a finger of a user's hand, detunes the antenna, e.g. by lowering the resonance frequency. This causes the wave generated by the frequency generator to be reflected to a considerable extent, in particular at the base point of the respective antenna, and can not be radiated. At the power detector, due to this increased power, a signal is provided as the first sensor output representing that increased power. This output signal may be, for example, a voltage signal. This may include an evaluation unit of the sensor as explained above, e.g. by thresholding or pattern matching, evaluating as the actuation signal and generating a switching signal as the second output, respectively.

Advantageously, a proximity sensor formed as described above can be produced simply and cost-effectively, with further advantages - as could be recognized in the context of the present invention, in particular in the course of detailed experiments - coming into use with a hob. On the one hand, the proximity sensor becomes metallic structures of a hob, for example a metallic frame, hardly noticeably influenced. The glass surface and the glass color of a hob plate play no significant role, which - should still affect the sensor - this can be compensated by the geometry of the antenna, which is easily adaptable.

The removal of a hob plate or glass plate from the sensor can be compensated by the antenna geometry. Here, the glass plate can rest directly on the proximity sensor or its antenna (s) or be spaced therefrom. The installation-specific tolerances affect the function of the proximity sensor in this case only insignificantly. A thin water layer arranged above the sensor, for example water vapor, also has an advantageously lower influence on the proximity sensor than the prior art.

Furthermore, by means of the proposed proximity sensor advantageously reliable between a desired actuation form and interference from RF applications, e.g. Microwave, W-LAN are distinguished. This is because an intended approach profile, in particular of a finger, corresponds to a signal of continuous signal rise or of a unique characteristic, which is advantageously distinguishable from interference signals in terms of signal shape and duration. In relation to the generated signal, the signals of a microwave are e.g. short. An undesired operation which does not correspond to the intended approach profile, e.g. by means of other types of bodies than e.g. a finger, can be avoided by evaluating or comparing the signal pattern generated by means of the at least one proximity sensor in an approximation.

In the context of the present invention, a control panel with at least one proximity sensor as described above is also proposed, wherein at least one interaction position at which a user can interact with the at least one proximity sensor or the control panel is defined on the control panel. In particular, manual interaction, ie via the hand of a user, in particular via a finger, is provided for. In this case, the interaction can preferably take place without contact. The control panel can have a surface for visualizing interaction positions, for example on a substrate on which the intended interaction positions are marked or visualized for the user, wherein the proximity sensor can be arranged adjacent to the surface, in particular on a surface opposite to the surface Side of the substrate.

In the control panel according to the invention it is provided that the at least one interaction position, in particular all, an antenna of the or a proximity sensor is assigned, by means of which the control panel generates a signal in response to a determined power on the same, in particular a switching signal. The switching signal can be generated by an evaluation device, which may preferably be part of a control of the control panel.

The control panel is preferably the control panel of a hob. In this case, the substrate may in particular be a glass pane which forms the hob plate. The control panel, in particular a cooktop, may preferably be designed, in particular by means of at least one evaluation device, to generate a switching signal via a respective proximity sensor if a signal output by the power detector has a stored characteristic, i.e. a predetermined approach profile corresponds, preferably that of a finger. This allows a cooktop to prevent undesired operations, e.g. through a saucepan or even a palm, to be able to prevent, i.e. due to different signal characteristics or approximation profiles.

By means of the present invention, a reliably functioning and advantageously lowable cooktop can thus be formed.

Further features and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention, with reference to the figures of the drawings which show essential to the invention, and from the claims. The individual features can be realized individually for themselves or for several in any combination in a variant of the invention. Preferred embodiments of the invention are explained below with reference to the accompanying drawings. Show it:

1 shows an example and schematically a proximity sensor with a

Evaluation device according to a possible embodiment of the invention;

2 shows an example and schematically a proximity sensor with a

A plurality of antennas and a multiplexer according to another possible embodiment of the invention;

3 shows by way of example and schematically a control panel according to a possible embodiment of the invention.

In the following description of the figures, the same elements or functions are provided with the same reference numerals.

Fig. 1 shows a proximity sensor 1 with a frequency generator 2 in the form of a frequency synthesizer module. To the frequency generator 2, a planar antenna 3 is coupled, for which purpose it is connected to the output 4 of the frequency generator via a feed line 5a, a directional coupler 6, and in particular its base point P.

The frequency generator 2 excites the antenna 3 at a fixed operating frequency with only low energy, in particular constant energy or power, wherein the antenna 3 has a high quality and low bandwidth at the operating frequency. The antenna 3 is presently a printed planar antenna 3, i.e. on a carrier substrate, not shown, which is easy to produce in a simple manner.

Connected to the antenna 3 - via the coupling element 6 and a conductor 5b - is also a power detector 7, English, power detector, which determines a power at the antenna 3, ie at its base P. The coupled by the antenna 3 power detector 7 determined power varies depending on the radiated from the antenna 3 power, the power detector 7 sees the returning wave, which is coupled by means of the directional coupler 6. As illustrated in FIG. 1, the radiated power can in particular vary and, as a result, the power determined at the antenna 3 when an interaction element 8 is guided into the electromagnetic field of the antenna 3, in particular its near field, its approach from the proximity sensor 1 to output a corresponding one Signal to be detected. The interaction element 7 can be a finger 8 of a user as shown, alternatively another body.

With introduction of the interaction element 8 into the antenna field, in particular its near field, the antenna 3 is detuned, starting e.g. of capacitive coupling, whereby power at the base 6 of the antenna 3 is reflected, but not radiated. This increased or varied power, i. the returning wave is detected by the power detector 7. As a result, a signal A corresponding to the increased power is provided at an output 9 of the power detector 7 by the same, e.g. an analog voltage signal. This can represent a first output signal of the proximity sensor 1.

Connected or coupled to the output 9 is an evaluation device 10 of the proximity sensor 1 in the form of a microcontroller, which correlates the signal at the output 9 with internal switching thresholds, alternatively or in addition to a stored signal pattern which corresponds to a predetermined approach profile, in dependence on the Correlation or comparison result of the same a switching signal B to produce or provide. This can be used as a further or alternatively single output signal of the proximity sensor 1 at an output 1 1, i. the evaluation device 10, are available. Alternatively or additionally, the switching signal B can be determined internally by the evaluation device 10, which e.g. Part of a controller can be further processed.

2 shows by way of example an embodiment of a proximity sensor 1, in which the proximity sensor 1 each has a plurality of antennas 3. In the embodiment of FIG. 2, these are fed via a multiplexer 12, ie selectively. As can be seen from FIG. 2, the multiplexer 12 is coupled or connected to the output 4 of the frequency generator 2. In each switching position 12a, 12b, 12c of the multiplexer 12 is ever an antenna 3 coupled to the output 4 of the frequency generator 2 and thus selectively energized on this. In this case, the multiplexer 12 can be controlled via the evaluation device 10, which preferably acts as a demultiplexer, ie via the control line 13.

In order to interrogate the antennas 3 at intervals, the multiplexer 12 is reversible via the control line 13 into its different switching positions, i.e. each for an interval within which the respective antenna 3 is thus fed. For this interval, the power detector 7, which is advantageously coupled to all the antennas 3 via a single input in connection with the line sections 5b, determines. depending on a directional coupler 6, a power to the antenna 3 and based on a sensor signal A, preferably to the evaluation device 10 to subsequently generate a switching signal B can.

In this case, all the antennas 3 can be excited at intervals in a continuous sequence one after the other, with the interval lengths preferably being chosen such that an approximation of an interaction element 8 to a respective antenna 3 can be reliably detected.

FIG. 3 shows by way of example a control panel 14, which is formed by means of a proximity sensor 1. The control panel 14 has a substrate 15 which provides a surface 1 6 at which interaction positions 17 are marked. The interaction positions 17 each define positions at which an interaction with a user, in particular via an interaction element 8, preferably a finger, is to take place.

For this purpose, each interaction position 17 is associated with an antenna 3 which is arranged such that an approximation of an interaction element 8 to the interaction position 3 can cause detuning of the antenna 3, ie a change in the power detectable by means of the power detector 7. For each antenna 3, a signal A which depends on the determined power can thus be generated, in the present case at intervals, alternatively, for example continuously, for example when a plurality of sensors are used. 1. This is supplied to each of the evaluation device 10 of the control panel 14, which generates A switching signals B in response to the signals.

The arrangement of the proximity sensor 1 in this case takes place on the surface 1 6 opposite side 18 of the substrate 15, in particular adjacent thereto, for. spaced or in abutment therewith. It is also conceivable here to form an antenna 3 or at least parts of the proximity sensor 1 directly on the substrate 15.

To form the control panel 14, it is also conceivable to provide a plurality of sensors 1, which are e.g. are formed by at least one antenna 3. Their output signals A and B can be routed to a higher-level evaluation unit of the control panel.

By means of the control panel 14 or a proximity sensor 1 is advantageously a cooktop, in general, for example, an electrical appliance can be formed, wherein the substrate 15 in the case of a hob is preferably a hob plate, in particular a glass. The evaluation device 10 may in this case be part of a cooktop control, wherein, depending on the switching signals B, for example hobs of the cooktop on or off, or eg up or down regulated. A cooktop can advantageously be easily enabled by means of the proximity sensor 1 to differentiate between the approach of an intended interaction element, in particular a finger, or a different element. For this purpose, a signal correlation functionality as described above can be implemented in the proximity sensor or a cooktop control formed therewith, in particular in the evaluation device. Here, a stored signal or approach profile can be correlated with those of an actual approach, so that a security function can be implemented in a simple manner. In other applications of the invention, the substrate may be, for example, a ceramic or a plastic. REFERENCE CHARACTERS

1 proximity sensor

2 frequency generator

3 antenna

Output 2

5a feed line

5b line

6 coupling element

7 power detector

8 interaction element

9 exit 7

10 evaluation device

1 1 output 10

12 multiplexers

13 control line

14 control panel

15 substrate

1 6 Surface 15

17 interaction position

18 to 1 6 opposite side 15

A first output signal

B second output signal

P foot point

Claims

claims

1 . Proximity sensor (1), in particular for use with a control panel (14), preferably a cooktop, characterized in that the proximity sensor (1) comprises at least one antenna (3), a frequency generator (2) and a power detector (7), wherein the at least one antenna (3) is coupled to its supply with the frequency generator (2), wherein the power detector (7) is provided to determine a power at the at least one antenna (3), which varies in dependence on the radiated power, and wherein the power detector (7) is further provided to output a signal (A) as a function of the determined power.

2. Proximity sensor (1) according to claim 1, characterized in that the proximity sensor (1) further comprises an evaluation device (10), in particular a μΟοηΐΓθΙΙβΓ, which is coupled to the power detector (7).

3. Proximity sensor (1) according to claim 2, characterized in that the evaluation device (10) based on the signal output by the power detector (7) signal (A) generates a switching signal (B), in particular by correlation of the power detector (7) output signal (A) with at least one switching threshold and / or correlation of the output by the power detector (7) signal (A) with a stored characteristic.

4. Proximity sensor (1) according to any one of the preceding claims, characterized in that the proximity sensor (1) comprises a plurality of antennas (3), in particular further comprises a multiplexer (12) via which a respective antenna (3) selectively to the frequency generator (2) can be coupled or selectively the power at an antenna (3) can be determined.

5. Proximity sensor (1) according to any one of the preceding claims, characterized in that the at least one antenna (3) is a planar, in particular printed antenna (3) and / or the antenna (3) via a coupling element (6) to the frequency generator (2) and / or the power detector (7) is coupled.

6. Proximity sensor (1) according to one of the preceding claims, characterized in that the frequency generator (2), the antenna (3) and the power detector (7), in particular also the evaluation device (10) and / or a multiplexer (12), are received on a common carrier substrate, in particular a printed circuit board, wherein the proximity sensor (1) in particular forms a one-piece module.

7. Proximity sensor (1) according to any one of the preceding claims, characterized in that the frequency generator (2) feeds the respective antenna (3) at a discrete frequency, in particular all the antennas (3) on a single discrete frequency.

8. Control panel (14) with a proximity sensor (1) according to one of the preceding claims, in particular for a hob, wherein on the control panel (14) at least one interaction position (17), at which a user can interact with the proximity sensor (1), in particular manually and / or non-contact, is defined, characterized in that the at least one interaction position (17) is associated with an antenna of the proximity sensor (1), by means of which the control panel (14) a signal (A) in response to a determined on the same power generates, in particular a switching signal (B).

9. Control panel (14) according to claim 8, characterized in that on the control panel (14) a plurality of interaction positions (17) are defined, which is associated with an antenna (3), wherein the antennas (3) in particular antennas (3 ) of one or more proximity sensors (1) of the control panel (14).

10. Control panel (14) according to any one of claims 8 and 9, characterized in that the control panel (14) comprises a substrate (15) on whose surface (16) the interaction positions (17) of the control panel (14) are defined, a respective antenna (3) is arranged adjacent to or on the surface (16) opposite side (18) of the substrate (15).

1 1. Control panel (14) according to one of claims 8 to 10, characterized in that the control panel (14) is formed via a respective proximity sensor (1) to generate a switching signal (B), if one by means of the power detector (7) of the proximity sensor (1) generated signal (A) corresponds to a stored characteristic.

12. Hob, comprising a proximity sensor (1) according to any one of claims 1 to 7 or a control panel (14) according to any one of claims 8 to 1 1.