DEVICE FOR DISTANCE-DEPENDENT DETECTION OF A MOBILE OBJECT AND METHOD FOR OPERATION THEREOF

Description

[0001] The invention relates to a device for the distance-dependent detection of a mobile object by means of the evaluation of reflected IR radiation, comprising a front panel with a first and a second surface and an IR sensor device comprising at least one IR light-emitting diode and an IR sensor spaced therefrom, wherein the at least one IR light-emitting diode is configured to emit IR radiation in the direction of the first surface of the front panel and through this, and the IR sensor is configured to detect reflected IR radiation through the second surface of the front panel and through this, as well as an IR evaluation device which is configured to evaluate the reflected IR radiation with regard to the presence of a mobile object, and a method for its operation.

[0002] For the operation of numerous devices, such as plumbing, industrial, and household appliances, it has recently become increasingly important to detect the proximity of one or more people in front of a device that can generally trigger switching operations, or of a suitable sensor mounted in or on it. In this context, it is also particularly important to determine the distance of a person from this device.

[0003] Object detection and the determination of the distance between the object and the sensor are usually carried out using IR radiation. The IR radiation emitted by a radiation source is reflected by the object, and the reflected IR radiation is evaluated by a radiation sensor. The sensors used for this purpose are generally located behind a plastic cover. A cover made of glass or ceramic is generally not used because the range for infrared radiation has so far been limited. In particular, if glass is coated, for example, this often leads to detrimental absorption of IR radiation. Existing IR sensor systems can only detect objects at a distance of more than 1 m behind transparent plastics or specially (visibly) exposed glass.

[0004] Preferably, the sensors should operate behind ceramic white printed glass.

[0005] Incidentally, IR sensor systems without distance measurement are known. In these, the IR sensor system is configured to react to a fixed distance at which it detects the presence of, for example, a person. For this purpose, a print is created or adjusted accordingly on a generally used front panel. However, this is very complex. The print must always be consistent in series production, as deviations have a significant impact on the set or adjustable distance. However, this cannot always be guaranteed, so the detection distance cannot be kept constant within a series.

[0006] Furthermore, only one distance can be set. Therefore, a person can only be detected if they are within this distance from the sensor system. Depending on the installation situation, this can also lead to the sensor constantly returning the message "Object detected," even though there is no mobile object, such as a person, in front of the sensor.

[0007] Furthermore, it is also known to perform distance measurements using the triangulation principle. For this purpose, either several infrared light-emitting diodes (LEDs) are arranged at different angles relative to a front panel, or only one IR LED is used as the transmitter, i.e., the radiation source, but a complex array IR sensor is used as the receiver, i.e., the radiation detector.

[0008] However, these options share the common disadvantage that the range of the sensors behind ceramic white printed glass is too short. No sensors with significant ranges are available for use behind ceramic white printed glass.

[0009] The publication DE 41 15 730 A describes an arrangement for object identification, consisting of at least one interrogation device and at least one data carrier, which is assigned to each object to be identified, wherein the interrogation device contains a pulse-modulated high-frequency transmitter and is further equipped with a receiver which is connected to an evaluation device for determining identification data for the objects.

[0010] Publication DE 197 00 836 C describes an optical sensor switch, in particular for a glass ceramic hob, with a light source and a light-sensitive signal sensor which is connected to a circuit and receives light from the light source, the circuit generating an output signal when the signal sensor receives light above a predetermined threshold value, a first light guide being coupled to the light source and a second light guide being coupled to the sensor, and the free ends of the two light guides being positioned in such a way that light emerging from the first light guide is reflected into the second light guide by a body which is to be brought close to the free end faces and is guided in the second light guide to the signal sensor, and the lateral surfaces of the light guides being embedded in a highly radiation-absorbing sheath.

[0011] The Austrian utility model AT 009 069 U1 describes a fitting, in particular a flush fitting and washbasin fitting, with at least one proximity sensor, a switching unit connected to or integrated therewith, to which a triggering device is connected, as well as a power supply and a viewing window. The viewing window is arranged within the detection range of the proximity sensor. The presence of an object, preferably a person or a hand, within the distance between the object and the fitting triggers the display of at least one symbol in the form of an alphanumeric text, pictogram, or graphic lettering in the viewing window.

[0012] Publication DE 10 2009 013 735 A describes a sensor for monitoring a surveillance area with a transmitting device that emits radiation, in particular electromagnetic radiation with a beam power or another wave, e.g., a sound wave, wherein the sensor is capable of detecting objects in the surveillance area. The sensor comprises means with which the instantaneous and / or average power per area of ​​energy impinging on a detected object, e.g., electromagnetic radiation from the transmitting device, can be determined. Adaptation means are also provided to prevent the instantaneous and / or average power per area of ​​energy impinging on the object from exceeding a predetermined value upon detection of an object in the surveillance area.The sensor is designed to first measure, using a comparatively low power that poses no or no significant hazard potential for people, whether objects are located within a predetermined range close to the transmitting device. In embodiments, the sensor uses the transmitting device to determine the distance to an object. Furthermore, the sensor can be designed to distinguish people from other objects.

[0013] Publication EP 2 208 831 A describes a method for contactless control of a sanitary facility, comprising a transmitter, a receiver, an evaluation unit, and a control unit, with which a room of the sanitary facility is monitored and at least one actuator of the sanitary facility is controlled. The room is monitored using a time-of-flight distance measurement. In one embodiment, a transmitted infrared signal is amplitude-modulated with a signal for the distance measurement, and the phase shift of the received modulation signal relative to the transmitted signal is measured.

[0014] The publication WO 2009 / 095014 A1 describes a device for monitoring a spatial volume, comprising at least two matrix distance measuring sensors with an emitter unit for emitting radiation pulses and a plurality of sensors for receiving reflections of these radiation pulses, which are arranged with respect to the spatial volume to be monitored in such a way that, based on the received reflections, image information and an additional, three-dimensional spatial image can be created, and a coverage of the spatial volume from several sides is possible, wherein the at least two matrix distance measuring sensors are assigned computer hardware and / or computer software which is capable of digitizing camera data and creating a height profile of the spatial volume to be monitored above a reference plane on the basis of this sensor data,whereby the created height profile is comparable with standard models, such as an average person, using the computer hardware and / or software.

[0015] Publication WO 2009 / 156063 A1 describes an infrared receiver circuit for processing a carrier-modulated infrared signal, comprising an amplifier circuit and a demodulator. A comparator is provided, which is designed to digitize the output signal of the amplifier circuit or of a bandpass filter connected downstream of the amplifier circuit by comparing it with a threshold value in order to generate a pulse train signal. The receiver circuit comprises a logic circuit designed to logically combine the pulse train signal of the comparator and the output signal of the demodulator in order to extract an additional output signal corresponding to the infrared signal from the pulse train signal.

[0016] Publication EP 2 497 867 A1 describes an actuation and display plate for a flushing device, wherein the plate consists of a non-conductive transparent material, wherein the plate has at least one viewing window and wherein behind the viewing window are arranged: at least one infrared light source, at least one proximity sensor which operates on the basis of light reflection and is sensitive to the wavelength range of the infrared light source and with which the flushing device can be triggered, and at least one display light source in the visible light range, wherein a rear coating of the plate is provided which has a transmission in the range between 1 and 15% for the visible light range and which has a transmission of more than 60% for the near-infrared light range. The actuation and display plate is in particular a glass plate.Preferably, the back coating has a transmission of more than 70% for the near infrared light range.

[0017] Publication DE 10 2012 210 851 A1 describes an induction cooking appliance comprising at least one IR sensor arranged beneath a cooktop plate for detecting infrared light from a cookware placed on the cooktop plate, wherein the IR sensor is thermally connected to a heat sink. The description of the figures mentions that the cooktop plate is permeable to at least part of the IR measurement spectrum of the IR sensor, so that the IR sensor can detect IR radiation emanating from a measurement spot on the floor, and a floor temperature can be derived therefrom.

[0018] Publication DE 10 2013 207 785 A1 describes an operating device for a household appliance, comprising an operating element that is secured to a control element receptacle of the household appliance controlled by the operating device by means of magnetic force and is movable relative to the control element receptacle and can be removably positioned therefrom. The operating element comprises a light guide having a light coupling region that is arranged at a lateral edge of the operating element further away than a light coupling region of the light guide. The operating device comprises an infrared transceiver for selecting a functional subunit of the household appliance. The infrared transceiver is arranged with transceiver units below the light guide and is designed for detection through the light guide.In one embodiment, the control element has a base that is permeable to light in the visible spectral range and the infrared range, at least in the areas where the light can be coupled into the optical fiber and in the areas where the transmitting / receiving units detect through the optical fiber. It is essential that the control device has an infrared transmitting / receiving device for determining the position of the control element.

[0019] Publication DE 10 2014 201 636 A1 describes a household appliance system comprising at least one household appliance, at least one first room monitoring detector, and at least one second room monitoring detector for contactless detection of an object in the vicinity of the at least one household appliance. These room monitoring detectors are coupled to the at least one household appliance, so that at least one action of at least one household appliance can be triggered based on the detection of at least one object. A first room monitoring detector has a lower energy consumption than a second room monitoring detector, and the household appliance system is configured to activate at least one second room monitoring detector when at least one first room monitoring detector has detected an object.It is also mentioned here that an IR sensor cannot detect through the glass or plastics commonly used in stove fronts because these are not transparent in the wavelength range of about nine micrometers and higher, which is important for IR sensors.

[0020] The publication DE 10 2015 011 386 A1 describes a method for operating a sanitary facility, comprising at least the following steps: a) Defining several zones of an environment of the sanitary facility; b) Detecting a current environmental situation by means of a sensor device; c) Defining a standard environmental situation; d) Monitoring the several zones by means of the sensor device; e) Triggering an action of the sanitary facility if a characterizable change in the environmental situation is detected in step d).

[0021] In embodiments, the sensor device of DE 10 2015 011 386 A1 comprises a plurality of light emitters, in particular infrared LEDs, which can separately reach several zones of the surroundings of the sanitary facility, and at least one light receiver. The sensor device is particularly configured to determine the position of users or objects in the surroundings of the sanitary facility, and preferably also their distance from the sanitary facility or the sensor device, based on the measurement of the propagation time of light pulses from light-emitting diodes (LEDs) in the visible or infrared spectrum.

[0022] The publication "Infrared Remote Control Receivers Vishay's TSSP4056 Sensor for Fast Proximity Sensing" by John Fisher, October 21, 2015, pages 1 to 9, describes an IR sensor operating at its maximum sensitivity and at neighboring, lower sensitivities to achieve improved measurement of the distance of a mobile object.

[0023] Against this background, the object of the invention was to provide a device for the distance-dependent detection of a mobile object, preferably of persons, but also of animals, etc., using an IR sensor device. Preferably, an improved measurement of the distance of the mobile object from the device should be possible. The sensor technology should function not only behind plastic covers, but also behind ceramic or glass covers. Their design should preferably enable high durability and thus a wide range of applications, while simultaneously being simple and cost-effective to manufacture. A further object of the invention was to provide a method for operating such a device.

[0024] This object is achieved according to the invention by a device for the distance-dependent detection of a mobile object and a method for its operation having the features of the corresponding independent patent claims. Preferred embodiments of the device according to the invention are listed in the corresponding dependent patent claims. Preferred embodiments of the method according to the invention correspond to preferred embodiments of the device according to the invention, and vice versa, even if this is not explicitly stated herein.

[0025] The subject matter of the invention is thus a device for the distance-dependent detection of a mobile object by means of the evaluation of reflected IR radiation, comprising a front plate with a first and a second surface and an IR sensor device comprising at least one IR light-emitting diode and an IR sensor spaced therefrom, wherein the at least one IR light-emitting diode is configured to emit IR radiation in the direction of the first surface of the front plate and through it, and the IR sensor is configured to detect reflected IR radiation through the second surface of the front plate and through it, as well as an IR evaluation device which is configured to evaluate the reflected IR radiation with regard to the presence of a mobile object, wherein an IR sensor is used which has a maximum sensitivity at a specific operating frequency fo, such that the sensitivity at frequencies f,which are above or below, is lower, wherein the operating frequency f is the frequency with which the IR light-emitting diode emits IR radiation, and wherein a glass pane is used as the front panel, which is at least partially coated on the first and / or second side of the front panel with an opaque but IR-permeable ceramic lacquer layer.

[0026] A mobile object within the meaning of the present invention is, in particular, a living being or a part of a living being. The mobile object is therefore, in particular, also a person or a part of a person, e.g., a hand or a foot.

[0027] The operating frequency f, also referred to as the clock frequency, is the frequency at which the IR LED emits IR radiation. The operating frequency f is therefore to be distinguished from the frequency of the IR radiation itself, which is referred to herein as the "IR frequency."

[0028] In the device according to the invention, the at least one IR LED is spaced apart from the IR sensor. This distance is generally selected appropriately depending on the intended use or location of the device. Generally, the distance between the IR LED and the IR sensor is at least 1 cm.

[0029] In the event that the front panel is a glass panel coated with a ceramic paint, in particular a glass panel coated with a white ceramic paint, the distance d LS between the IR LED and the IR sensor is preferably at least 4 cm and even more preferably at least 6 cm. This is particularly advantageous if the presence of a mobile object is to be detected at a distance d FO between the second surface of the front panel and the mobile object of 1 m or more. If a distance d FO of up to 1.2 m is to be detected with the device according to the invention, it is advantageous when using a glass panel coated with a white ceramic paint as the front panel if the distance d FO is at least 10 cm and preferably in the range of 12 to 15 cm, in particular in the range of 13 to 14 cm.

[0030] According to the invention, the front panel is made of glass. Printed or unprinted glass panes can be used for this purpose, as long as they are transparent to IR radiation. Furthermore, Parsol® glass from Saint Gobain or a similar gray glass can also be used. This glass is a completely colored float glass. The detection of the distance of the mobile object achievable according to the invention will depend not only on the properties of the IR sensor system but also, in particular, on the IR permeability of the front panel.

[0031] According to the invention, the front panel is a glass panel, optionally coated. Glass offers good weather resistance and thus ensures the protection of the device according to the invention. Furthermore, glass is easy to clean, which also enables use in areas where frequent cleaning is necessary, particularly in areas where good hygiene is important. Furthermore, transparent and non-transparent areas can be created on glass, with transparent areas being particularly advantageous for enclosing the control unit with a display. The front panel generally has a thickness of 1 to 10 mm, preferably 2 to 5 mm, particularly preferably 3 to 4 mm. Flat glass produced using the float process is preferably used for the front panel.

[0032] Furthermore, according to the invention, it is preferred that the front panel of the device be made of tempered single-pane safety glass. This provides a scratch-resistant surface and high mechanical strength. It also serves to protect the device. This allows for a wide variety of applications that require, for example, a robust surface for the device.

[0033] In a particularly preferred embodiment of the invention, the front panel consists of an opaque glass pane. In this case, it is again preferred that the opaque glass pane comprises a glass pane provided with an opaque coating, or that the opacity is achieved by completely coloring the glass. An organic or ceramic coating, the latter particularly for glass panes, can be used as the opaque coating, preferably as a print. This makes it possible for the IR sensor system located behind the front panel and any other components such as an IR evaluation device to be invisible to a user of the device, in particular a person as an example of a mobile object.

[0034] The at least one IR LED and / or the IR sensor can be mounted on the front panel or on a second panel spaced apart from the front panel. Preferably, the at least one IR LED and the IR sensor are mounted on a second panel spaced apart from the front panel. The second panel can also be a plastic or, preferably, glass panel, but can also be a circuit board, for example, which can optionally be equipped with additional components.

[0035] The IR evaluation device is preferably arranged or at least connected to the first surface of the front panel or an optionally used second panel. Generally, the first surface of the front panel is the surface of the front panel facing away from the user. Thus, the IR evaluation device is preferably located on the side of the front panel facing away from the user.

[0036] The term "IR evaluation device" encompasses electronic components, conductor track structures, solder joints, and possibly other components. The IR evaluation device can, for example, be arranged directly on the front panel, on a flex cable, or on a separate circuit board. If a separate circuit board is used as the second board, this can in turn be arranged on the first surface of the front panel. In this case, the circuit board has a first and a second side, with conductor track structures, solder joints, electronic components, and possibly other components, arranged on the first side of the circuit board. The circuit board can also have two or more layers.

[0037] In the device according to the invention, a glass pane is used as the front panel, which is at least partially coated on the first and / or second side of the front panel with an opaque but IR-permeable ceramic lacquer layer. This has the advantage that the structure of the device can be located behind the front panel as seen by a user, and the front panel allows the device to be designed in a visually appealing manner.

[0038] According to the invention, a ceramic-printed glass plate (white glass) is particularly preferably used as the front plate, since this structure does not have any exposures or color differences on the front. The thickness of the ink layer can be selected with regard to the desired properties of the device. Ceramic screen printing inks are preferably used. Ceramic screen printing inks consist of pigments, glass frits, i.e. glass particles with a specific grain size distribution, and organic solvents. After application to a glass plate, these are dried physically in a first step by evaporation of the solvent, preferably using a circulating air dryer at a temperature of less than 200 °C. In a second step, the dried ink layer is irreversibly fused to the glass plate at a temperature of generally > 600 °C in a thermal sintering or enameling process.Generally, the glass plate is simultaneously refined into single-pane safety glass.

[0039] In addition to ceramic inks, ceramic conductive pastes can also be advantageously used to create contacts between electronic components on the front panel and / or an optionally present second panel, and thus also for conductive tracks. "Ceramic conductive paste" is understood to be a fireable paste that generally contains both a ceramic component and a metal component. Such pastes are known, for example, in the field of thick-film technology (also known as "thick-film technology"). In addition to the ceramic component and the metal component, such fireable pastes generally contain other additives such as a solvent, for example at least one alcohol such as terpineol, which influences the rheology of the paste. This is particularly important when the paste is applied using a printing process. The proportion of the ceramic component in the fireable paste is preferably 10–30% by weight.-%, the proportion of metal particles, which preferably have a grain size of no more than 15 µm, in particular silver particles, 60-90 wt.%, preferably 70-85 wt.%, and the proportion of solvent 5-10 wt.%, each based on the total weight of the conductive paste. The ceramic conductive paste can be low-melting or high-melting. The low-melting paste used herein is a paste with a melting point of 500-600 °C, preferably 500-540 °C, and the high-melting paste is a paste with a melting point of 600-700 °C, preferably 650-680 °C.

[0040] The ceramic component of the conductive paste ensures its adhesion to a glass substrate. During firing, the ceramic portion of the ceramic conductive paste applied to the substrate can fuse with the surface of the glass plate, creating a strong bond between the ceramic conductive paste and the glass plate. This ensures particularly good adhesion to a glass substrate. It also enables high resistance to environmental influences such as UV radiation and adhesives used during further processing.

[0041] The ceramic component generally consists of inorganic, non-metallic materials, which are usually crystalline and contain metallic and non-metallic elements. The ceramic component is preferably glass frit. The expansion coefficient and melting range of the glass frit are advantageously adapted to the carrier substrate. Metal oxides, metal nitrides, metal carbides, or a mixture of these materials are generally particularly suitable as ceramic components. The ceramic component is usually in powder or dispersed form.

[0042] The metal component of the conductive paste ensures the highest possible conductivity. Accordingly, the conductive paste should contain highly conductive materials. Precious metals such as silver, gold, platinum and palladium are particularly preferred as metal components. Silver conductive paste is particularly preferred as a ceramic conductive paste. The precious metals mentioned can be used individually or in combination. Alloys of precious metals, for example gold or silver with platinum or palladium, can also be used. The advantage of precious metals as a metal component is that they do not have to be fired in a protective atmosphere. Furthermore, non-precious metals can also be used as metal components, as long as good conductivity and durability are guaranteed. These metals can also be used individually, in combination or as alloys, both with each other and with precious metals.For conductive pastes containing non-precious metals, those containing copper are preferred.

[0043] In ceramic conductive pastes, the average diameter of the metal particles is generally no more than 15 µm, preferably from 1 to 15 µm. The ceramic conductive paste particularly preferably contains silver particles. In the fired ceramic conductive paste, the metal particles are generally in contact with each other in such a way that a continuous electrically conductive structure is formed.

[0044] In a further preferred embodiment of the device according to the invention, the IR sensor device and the IR evaluation device are designed to determine the distance of a mobile object. The IR sensor device and the IR evaluation device are preferably designed to evaluate the IR sensor signals determined at a plurality of operating frequencies f with regard to the distance of the mobile object. Finally, it is also preferred that the IR sensor device and the IR evaluation device are designed to determine a distance of the mobile object from the second surface of the front panel in the range of 0.1 to 1.5 m by evaluating IR sensor signals that were recorded at operating frequencies f for which the ratio f / fo is in the range of 0.25 to 1 or 1 to 1.75.

[0045] In a preferred embodiment of the device according to the invention, the IR sensor device contains several IR light-emitting diodes that emit IR radiation of different IR frequencies.

[0046] The IR sensor can be a single sensor or an array sensor. An array sensor enables better location-dependent analysis of the recorded reflected IR radiation.

[0047] In a further preferred embodiment of the device, a relationship is stored in a control unit, e.g. a microcontroller, between sensor signals of the IR sensor for certain operating frequencies f and the distance of the mobile object from the second surface of the front plate.

[0048] Infrared remote controls can, in principle, interfere with the detection of a mobile object by means of infrared radiation and cause unwanted triggering, i.e., detection of the presence of a mobile object. In a particularly preferred embodiment, the device according to the invention is therefore designed to prevent possible interference by an infrared remote control. This is generally achieved by using suitably designed software, by means of which signals from an infrared remote control are detected and taken into account when carrying out the method according to the invention. This software recognizes, based on the start condition contained in IR remote control signals, e.g., a 50 ms high signal, whether it is the signal emitted by the IR sensor device of the device according to the invention or an IR remote control signal. Thus, for example, during an IR remote control sequence, the object detection, i.e.,The detection of the presence and, if applicable, the distance of a mobile object can be briefly interrupted. This prevents interference.

[0049] The invention also relates to a method for operating a device for distance-dependent detection of a mobile object by means of the evaluation of reflected IR radiation, comprising a front plate with a first and a second surface and an IR sensor device comprising at least one IR light-emitting diode and an IR sensor spaced therefrom, wherein the at least one IR light-emitting diode is configured to emit IR radiation in the direction of the first surface of the front plate and through it, and the IR sensor is configured to detect reflected IR radiation through the second surface of the front plate and through it, as well as an IR evaluation device which is configured to evaluate the reflected IR radiation with regard to the presence of a mobile object, wherein an IR sensor is used which has a maximum sensitivity at a specific operating frequency fo, such thatthat the sensitivity is lower at frequencies f which are higher or lower, wherein the operating frequency f is the frequency at which the IR light-emitting diode (5) emits IR radiation, and wherein a glass pane is used as the front plate (1), which is at least partially coated on the first (2) and / or second (3) side of the front plate (1) with an opaque but IR-permeable ceramic lacquer layer, and wherein the following steps are carried out: , (a) Emitting IR radiation from the at least one IR light-emitting diode toward and through the first surface of the front panel; (b) Detecting reflected IR radiation by and through the second surface of the front panel by means of the IR sensor; and (c) Evaluating the reflected IR radiation with respect to the presence of a mobile object by the IR evaluation device.

[0050] In the method according to the invention, for the implementation of which the device according to the invention is particularly configured, a microcontroller generally controls an IR LED. The IR LED is preferably switched on and off with a duty cycle of between 40 and 60%, for example with a duty cycle of 50%, and for example with a frequency f 0 , e.g. 56 kHz. This control can be continuous, for example. If maximum sensitivity and thus maximum range of the sensor device is to be achieved, the frequency f = f 0 is selected for the control frequency f, ie operating frequency f, of the IR LED.

[0051] Subsequently, the analog signal from the IR sensor is generally digitized using the analog-to-digital converter (ADC) located in the microcontroller, preferably after a short waiting period Δt in the range of 10 to 30 ms for the system to settle (for example, 20 ms). However, the analog signal can also be pre-filtered beforehand using an analog circuit in hardware, for example, a low-pass filter consisting of a resistor and a capacitor.

[0052] Once the IR sensor signal has been digitized, it is generally further evaluated. For this purpose, the digitized IR sensor signal can be enhanced using a digital filter, e.g., a low-pass filter and / or a bandpass filter. Typically, the filtered IR sensor signal is then evaluated for its amplitude. If the signal amplitude exceeds a specified value, this is interpreted as a mobile object being detected within the detection range. The specified value is preferably in a range of 40 to 60%, e.g., 50%, of the maximum amplitude value.

[0053] To avoid interference, this binary signal (object detected or no object detected) can be evaluated with an additional digital filter or corresponding logic, for example, to determine its temporal progression. For example, if the "object detected" signal is present only for a very short time and immediately disappears, this could be caused by an interference signal. If, as mentioned above, these short pulses are filtered out using a digital filter or functional logic, false results can be avoided.

[0054] If the distance between a mobile object and the sensor device is to be determined, the operating frequency f used to control the IR LED is preferably increased or decreased. The IR sensor signal is then evaluated again as described above. This can be done successively, for example, until no more mobile objects are detected. This makes it possible to determine the location of the mobile object. The frequencies f to be used to control the IR LED can be assigned to specific distances d FO using a "lookup table," for example. This "lookup table" can be determined, for example, through a series of tests. This measurement can be repeated as often as required, for example, to achieve continuous evaluation.Depending on the desired application of the device according to the invention, only certain distance ranges can be evaluated, so that the computing and time expenditure in the microcontroller is lower.

[0055] In the method according to the invention, a switching process is generally initiated in step (d) following step (c). This can involve, for example, switching on a light, playing music, acoustically or visually issuing an occupancy signal or other information, or carrying out measures that prepare an action presumably to be performed by a person, e.g., opening a cupboard or container, etc., providing a device, etc. The type of switching process can also be coordinated with the determined distance of the person from the person according to the invention. If necessary, the type of switching process can also depend on the time of day.

[0056] The method according to the invention thus provides, in particular, that one or more infrared LEDs are clocked at a specific frequency. This means that infrared radiation is emitted at a specific frequency. The infrared sensor can generally distinguish this clocked light from daylight and other interference sources and provides an output signal analogous to the reflected signal level, which is generally digitized and smoothed by software using a digital filter. If the filtered signal exceeds a predetermined level, this fact is passed on for the respective distance range as "object detected" information. For distance determination in the method, it is also essential that the clock frequency is varied and the received signals are evaluated with regard to their dependence on the clock frequency. This is particularly important in the case of a limited sensitivity of the infrared sensor, i.e.at a clock frequency different from an operating frequency.

[0057] In a preferred embodiment of this method, the IR sensor device is operated at several operating frequencies f and the IR sensor signals determined at several operating frequencies f are evaluated with regard to the distance of the mobile object.

[0058] Furthermore, a method is preferred according to the invention in which, for measuring a distance of the mobile object of up to 0.8 m from the second surface of the front panel, the IR sensor device is operated with reduced sensitivity by operating the IR sensor device at an operating frequency f that is 2 to 10% lower or higher than fo . Particularly preferably, the IR sensor device is operated at an operating frequency f that is higher than fo . It has been found that then no harmonics fall within the maximum sensitivity of the sensor and thus no undesired false triggering occurs.

[0059] There are direct and indirect possibilities for determining the presence and, if applicable, the distance of the mobile object from the device according to the invention.

[0060] In a preferred embodiment of the method according to the invention, the IR radiation directly reflected from the mobile object is used to determine the presence and, if applicable, the distance of the mobile object.

[0061] In addition or as an alternative to this, in a further embodiment of the method according to the invention for determining the presence and, if applicable, the distance of the mobile object, the indirectly reflected IR radiation from immobile objects attributable to the mobile object can be used. For this purpose, for example, a door or another object, e.g. a curtain, can be used, the movement of which is an indication that the mobile object in question is located at this point or very close to it. This embodiment of the method according to the invention or of the device according to the invention configured for this purpose is particularly advantageous when the device is used in a small and / or narrow space, e.g. a room 80 cm wide and 2 m long.

[0062] In this embodiment, it is advantageous if the operating frequency f with which the IR LED is controlled is set to a value appropriate to the application, e.g. a frequency f that corresponds to a slightly reduced range d FO. This operating frequency can, for example, be 20% higher than the frequency f 0. Subsequently, as in the embodiment mentioned above, in which the IR radiation reflected directly from the mobile object is evaluated, the IR sensor signal is usually digitized by the microcontroller after a short waiting time. This digitized signal can then be further enhanced using a digital filter, e.g. a low-pass or band-pass filter. The resulting signal is then generally differentiated. This means that the derivative of the signal with respect to time is formed and the change over time is calculated. This can be done, for example, using another digital filter.The received signal is evaluated for its amplitude. This signal can be either positive or negative. According to the invention, it is preferred in this embodiment that both directions are taken into account. If the pre-filtered sensor signal changes, for example, by -30% in one second, this can be interpreted as "a door in a confined space is opened."

[0063] In this way, the IR sensor device can advantageously detect an area in a narrow space which cannot be detected by the previously described method due to the spatial geometry.

[0064] The method of applying a preferably used fireable ceramic color and / or conductive paste to a preferably used glass plate as a front plate and / or second plate is not particularly restricted according to the invention. However, it is preferred that the application be carried out using screen printing or inkjet technology. This has the advantage that commercially available fireable ceramic color or conductive pastes can be used, which are generally tailored to these processes. Screen printing is particularly preferred because it is an efficient and cost-effective process, particularly with regard to the equipment technology and the ceramic color and conductive pastes tailored to screen printing. If a particularly high resolution is required, for example with structures below 50 µm, inkjet technology is preferred, which, unlike screen printing, does not require masks and offers even better resolution.

[0065] When applying a fireable ceramic color or conductive paste, a desired structuring can be carried out, which can then be fixed during the subsequent firing of the ceramic color or conductive paste.

[0066] The invention has numerous advantages. The device according to the invention can be used widely, not only in the home but also in factories and hospitals. In the home, use in the sanitary sector is particularly advantageous. The invention has the advantage that automatically operating switches can be realized in which an IR sensor device, i.e. IR light-emitting diode, and IR sensor, are located behind glass or glass ceramic. In some embodiments it is also possible for the IR sensor device to be located behind glass or glass ceramic coated with a white ceramic paint, so that it is not visible from the outside. The invention makes it possible to detect mobile objects at a distance of generally up to 2 m, regardless of the respective lighting conditions in the vicinity of the IR sensor.

[0067] The invention also offers significant advantages in the series production of the device according to the invention. It is not always possible to achieve exactly the same permeability for electromagnetic radiation, particularly IR radiation, on a ceramic or organically printed front panel, e.g., a glass panel. This would require very complex technical intervention in the printing process. The method and device according to the invention offer the significant advantage of calibrating the device or its IR sensor device during a manufacturing process. The fully installed IR sensor device can, for example, be applied to a test setup on which a defined object is located at a defined distance.For example, testing software can calibrate the sensor device in the commonly used microcontroller by successively changing a parameter that generally influences the transmission frequency used to control the IR LED. This ensures exactly the same ranges in a series product.

[0068] The invention is described below with reference to Figures 1 to 5 further explained.

[0069] Fig. 1 shows parts essential to the invention of a non-restricted embodiment of a device according to the invention for distance-dependent detection of a mobile object by means of the evaluation of reflected IR radiation.

[0070] In Fig. 1 (a)A side view shows an IR sensor device 4 located behind a first glass plate 1 as a front plate on a second glass plate 9. The sensor device 4 is located between the first surface 2 of the first glass plate 1 and the second glass plate 9. The second surface 3 of the first glass plate 1 faces a person as a mobile object. An IR evaluation device and other electronic components and conductive structures, as well as ceramic color layers, are omitted here.

[0071] One or more infrared LEDs on the second glass plate 9 are clocked at a specific frequency as the operating frequency f. These LEDs emit their infrared radiation forward in the direction of the arrow through a ceramic print (not shown here) and the first glass plate. The infrared LEDs can also be located on a circuit board. In any case, the IR radiation emerges from the glass plate 1 and spreads out in a directed manner in the space in front of the device. If an object is located in the detection area in front of the sensor, i.e. at a distance at which the IR sensor device can detect the object and determine the distance, the infrared light is reflected and then reflected back towards the first glass plate and thus the IR sensor device.

[0072] Fig. 1(b) shows a front view of the second glass plate 9 with the IR sensor device 4. The IR sensor 5 and the IR sensor 6 are spatially separated.

[0073] IR sensor 6 is a so-called receiver module, which can distinguish the reflected IR radiation, which is also timed, from daylight and other interference sources and provides an analog output signal based on the reflected signal level. In this non-limiting example, a receiver module with integrated filters and a demodulator, e.g., the TSSP-6038 sensor from VISHAY, is used for this purpose.

[0074] A microcontroller, for example, is used as an IR evaluation device (not shown here). The IR radiation incident on the IR sensor 6, for example, reflected by a mobile object, is evaluated as an output signal by a microcontroller, for example, as follows: The signal is digitized using an AD converter and enhanced using software with a digital filter, e.g., a low-pass filter that filters out higher frequencies and thus unwanted interference. The filtered signal is then evaluated for amplitude and time behavior. First, the increase in amplitude above a certain threshold, e.g., above 50% of the maximum signal amplitude, is evaluated. If the already filtered signal exceeds this threshold, the information "Object detected" is passed to a function logic for the currently set transmission frequency.

[0075] Fig. 2shows a block diagram of an example sensor TSSP-6038 from VISHAY.

[0076] Fig. 3 shows the bandpass behavior of an IR sensor usable in accordance with the present invention, e.g., a TSSP-6038 sensor from VISHAY. An IR sensor usable in accordance with the invention has a maximum sensitivity at a specific operating frequency fo, so that the sensitivity is lower at frequencies f above or below it.

[0077] In order to be able to measure the distance, especially different distance ranges, with this IR sensor, the transmission frequency, ie working frequency, of the IR LEDs is specially selected, whereby the Fig. 3The typical bandpass behavior of the IR sensor, i.e., the receiver component, shown is utilized. As shown, the IR sensor is designed for a specific operating frequency. For example, the TSSP-6038 IR sensor operates at 38 kHz, or the TSSP-6056 IR sensor operates at 56 kHz. Other receiver components are also possible, as many IR sensors exhibit this typical bandpass behavior. By shifting the operating frequency, i.e., by varying the operating frequency of an associated IR LED, the sensitivity of the receiver component is reduced. If the operating or transmitting frequency of the infrared LEDs is increased or decreased, the sensor becomes less sensitive.

[0078] The distance to a mobile object can be determined as follows. In order to detect a mobile object, in particular a person, at a distant distance (e.g. 1.2 m), the sensitivity of the IR sensor is set very high. This is achieved by setting the transmission frequency of the infrared LED (IR-LED) close to the sensitivity maximum (f ≈ f 0 ). If an object or person is to be detected at close range (e.g. 0.2 m), the sensitivity of the IR sensor is greatly reduced. This is achieved by setting the transmission frequency of the infrared LED far away from the sensitivity maximum at f 0 (e.g. f = 1.5 x f 0 ). All distances in between can be set using this principle. This means that any number of intermediate ranges can be created and evaluated.

[0079] To determine the distance as accurately as possible, measurements should preferably be taken at different distances. Based on these results, a lookup table with interpolated intermediate steps can then be created, for example. These relationships can be stored appropriately in the IR evaluation device, e.g. a microcontroller. The microcontroller then works with these values ​​for the relationship between operating frequency and distance. Based on this relationship, the distance of an object in front of the IR sensor can therefore in principle be determined by successively changing the operating frequency. It is then possible, for example, to calculate in which sub-area in front of the device according to the invention the object is located. Almost any number of intermediate steps can be implemented (e.g. 5 cm steps).

[0080] The Figures 4 and 5show the functioning of an embodiment of the device according to the invention, which is particularly suitable for narrow and / or small spaces. Fig. 4 shows the situation for a closed door 10 and Fig. 5 the situation for an open door 10. 7 means the IR radiation emitted by an IR LED, while 11 means the IR radiation reflected by the door 7 or walls 13.

[0081] If the device according to the invention is used in a narrow / small space, the additional problem when using the IR sensor device is that the walls 13 and the door 10 already strongly reflect IR radiation and thus determine the sensor signal of the IR sensor. Because the radiation angle of infrared LEDs is generally not 0°, this effect will occur differently depending on the infrared LED and printing ink, e.g. in the case of a glass plate as the front panel. If this effect occurs, a large detection range, i.e. a wide distance range for the detection of a mobile object, would not be possible with the preferred procedure described above. However, this problem can be remedied according to the invention by evaluating the time and amplitude behavior of the sensor signal of the IR sensor differently. For this purpose, the change in the sensor signal per unit of time (derivative of the time behavior) is generated.This signal is evaluated in terms of both positive and negative changes.

[0082] If the device according to the invention is, for example, as in Fig. 4 As shown in a narrow room with a door 10, the room already delivers a sensor signal to the IR sensor device 4, in particular its IR sensor, due to the reflection of the IR radiation on walls 13 and door 10. If the door 10 is opened as shown in Fig. 5Now opened, as shown, the reflection of the IR radiation that is thrown back from the room to the IR sensor is reduced. Instead, a large portion will leave the room as IR radiation 12. This negative change in the sensor signal can therefore be assumed to be the detection of a moving object in the long-range. This allows the information "object detected" to be passed on. In any case, by evaluating the time and amplitude behavior of the reflected IR radiation registered by the IR sensor, the presence of, for example, a person can be determined from a greater distance than with normal evaluation methods. This means that longer ranges are also possible in confined / small spaces. List of reference symbols

[0083] 1Front panel 2First surface of the front panel, facing away from a mobile object, e.g. a person 3Second surface of the front panel 4IR sensor device 5IR light-emitting diode, infrared light-emitting diode (LED) 6IR sensor 7Emitted IR radiation (from the IR light-emitting diode) 8Reflected IR radiation 9Second panel 10Door 11Indirectly reflected IR radiation registered by the IR sensor 12Indirectly reflected IR radiation not registered by the IR sensor 13Wall

Claims

1. Apparatus for the distance-dependent detection of a mobile object by evaluating reflected infrared radiation, IR radiation (8), comprising a front plate (1) with a first (2) and a second surface (3) and an IR sensor device (4), comprising at least one IR light-emitting diode (5) and an IR sensor (6) spaced apart therefrom, wherein the at least one IR light-emitting diode (5) is arranged to emit IR radiation (7) in the direction of the first surface (2) of the front plate (1) and through it, and the IR sensor (6) is set up to detect reflected IR radiation (8) through the second surface (3) of the front panel (1) and through it, as well as an IR evaluation device, which is set up to evaluate the reflected IR radiation (8) with regard to the presence of a mobile object, characterized in that an IR sensor (6) is used as the IR sensor (6), which has maximum sensitivity at a specific operating frequency fo, such that the sensitivity at frequencies f above or below this is lower, wherein the operating frequency f is the frequency at which the IR light-emitting diode (5) emits IR radiation, and wherein a glass pane is used as the front plate (1), which is at least partially coated on the first (2) and / or second (3) side of the front plate (1) with an opaque but IR-permeable ceramic lacquer layer.

2. Apparatus according to claim 1, characterized in that the at least one IR light-emitting diode (5) and the IR sensor (6) are mounted on a second plate (9) spaced apart from the front plate.

3. Apparatus according to claim 1 or 2, characterized in that the front panel (1) consists of an opaque glass pane.

4. Apparatus according to claim 3, characterized in that the opaque glass pane (1) comprises a glass pane provided with an opaque coating.

5. Apparatus according to one of claims 1 to 4, characterized in that the IR sensor device (4) and the IR evaluation device are designed to determine the distance of a mobile object.

6. Apparatus according to claim 5, characterized in that the IR sensor device (4) and IR evaluation device are designed to evaluate the IR sensor signals determined at several operating frequencies f with regard to the distance of the mobile object.

7. Apparatus according to claim 6, characterized in that the IR sensor device (4) and IR evaluation device are designed to determine a distance of the mobile object from the second surface (3) of the front panel in the range from 0.1 to 1.5 m by evaluating IR sensor signals that were registered at operating frequencies f for which the ratio f / fo is in the range from 0.25 to 1 or 1 to 1.75.

8. Apparatus according to one of claims 1 to 7, characterized in that the IR sensor device (4) contains several IR light-emitting diodes (5) that emit IR radiation of different IR frequencies.

9. Apparatus according to one of claims 1 to 8, characterized in that a correlation between sensor signals of the IR sensor (6) for certain operating frequencies f and the distance of the mobile object from the second surface (3) of the front panel (1) is stored in a control unit.

10. Method for operating an apparatus for distance-dependent detection of a mobile object by evaluating reflected infrared radiation, IR radiation (8), comprising a front plate (1) with a first (2) and a second surface (3) and an IR sensor device (4), comprising at least one IR light-emitting diode (5) and an IR sensor (6) spaced apart therefrom, wherein the at least one IR light-emitting diode (5) is arranged to emit IR radiation (7) in the direction of the first surface (2) of the front plate (1) and through it, and the IR sensor (6) is arranged to detect reflected IR radiation (8) through the second surface (3) of the front plate (1) and through it, and an IR evaluation device which is designed to evaluate the reflected IR radiation (8) with regard to the presence of a mobile object, wherein an IR sensor (6) is used which has maximum sensitivity at a specific operating frequency fo, such that the sensitivity at frequencies f above or below this is lower, wherein the operating frequency f is the frequency at which the IR light-emitting diode (5) emits IR radiation, and wherein a glass pane is used as the front plate (1), which is coated on the first (2) and / or second (3) side of the front plate (1) is at least partially coated with an opaque but IR-transparent ceramic lacquer layer, and wherein the following steps are carried out in the method: (a) emitting IR radiation (7) from the at least one IR light-emitting diode (5) in the direction of the first surface (2) of the front panel (1) and through it; (b) detecting reflected IR radiation (8) by the second surface (3) of the front panel (1) and through it by means of the IR sensor; and (c) evaluating the reflected IR radiation (8) by the IR evaluation device with regard to the presence of a mobile object.

11. Method according to claim 10, characterized in that the IR sensor device (4) is operated at several operating frequencies f and the IR sensor signals determined at several operating frequencies f are evaluated with regard to the distance of the mobile object.

12. Method according to claim 10 or 11, characterized in that, in order to measure a distance of the mobile object of up to 0.8 m from the second surface (3) of the front panel (1), the IR sensor device (4) is operated with reduced sensitivity by operating the IR sensor device (4) at an operating frequency f that is 2 to 10% lower or higher than fo.

13. Method according to one of claims 10 to 12, characterized in that the IR radiation (8) reflected directly from the mobile object is used to determine the presence and, if applicable, the distance of the mobile object.

14. Method according to one of claims 10 to 13, characterized in that the indirectly reflected IR radiation (11) from immobile objects (9, 10) assignable to the mobile object is used to determine the presence and, if applicable, the distance of the mobile object.