METHOD FOR HEATING AN ULTRASONIC TRANSDUCER AND ULTRASONIC TRANSDUCER

Abstract

A method for heating an ultrasonic transducer, in which an interior of the ultrasonic transducer together with a diaphragm element is heated by thermal radiation of a component, the temperature of the diaphragm element being increased to a temperature above the freezing point. The heating is achieved by a component which in a first operating mode is used to implement a transmitting and/or receiving operation of the ultrasonic transducer, and in a second operating mode is operated in such a way that the component has an increased electrical power loss compared to the first operating mode.

Claims

1-10. (canceled)

11. A method for heating an ultrasonic transducer, in which an interior (16) of the ultrasonic transducer together with a diaphragm element is heated by thermal radiation, the temperature of the diaphragm element being increased to a temperature above the freezing point, the method comprising: heating the diaphragm by a component, wherein in a first operating mode, the component is used to implement at least one of a transmitting operation and a receiving operation of the ultrasonic component, and in a second operating mode, the component is operated such that the component has an increased electrical loss compared to the first operating mode and heats the diaphragm.

12. The method as recited in claim 11, wherein the second operating mode comprises a transmission of transmit pulses of a piezo element that are one of: (i) extended compared to the first operating mode, and (ii) have a higher frequency as compared to the first mode.

13. The method as recited in claim 11, wherein the second operating mode comprises a transmission of transmit pulses of a piezo element outside of the resonant frequency of at least one of the diaphragm element and the piezo element.

14. The method as recited in claim 13, wherein for determining the frequency of the transmit pulses, an impedance measurement is performed on the diaphragm element.

15. The method as recited in claim 11, wherein the second operating mode comprises an operation of a processor core of a microcontroller that results in an increased load on the processor core.

16. The method as recited in claim 11, wherein a component temperature of at least one component involved in the second operating mode is monitored and the second operating mode is implemented only below a temperature threshold.

17. The method as recited in claim 11, wherein the second operating mode alternates with the first operating mode.

18. The method as recited in claim 11, wherein the second operating mode is controlled as a function of the result of an impedance measurement of the diaphragm element.

19. An ultrasonic transducer, comprising: a diaphragm element which is excitable to oscillations by a piezo element; electronic components including a microcontroller having a processor core and a transmission output stage for controlling the piezo element; wherein the electronic components being designed, in a first operating mode, to implement at least one of a transmitting operation and a receiving operation of the ultrasonic component, and, in a second operating mode, to operate at an increased electrical loss compared to the first operating mode.

20. The ultrasonic transducer as recited in claim 19, further comprising an arrangement for detecting the component temperature of the electronic components.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 shows a highly simplified longitudinal section through a sonic transducer, which may be operated using a method of the present invention.

[0020] FIG. 2 shows a diagram with a representation of the impedance over the frequency.

[0021] FIG. 3 shows a block diagram for explaining the operation according to the present invention of the sonic transducer.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0022] Identical elements and elements having the same function are provided with the same reference numerals in the figures.

[0023] FIG. 1 shows in greatly simplified fashion an ultrasonic transducer 10, as it is used in particular as a component of a driver assistance system in a motor vehicle. For this purpose, usually multiple ultrasonic transducers 10 are installed laterally adjacent to each other in corresponding installation openings of a bumper. Since it is known per se and not essential to the invention, regarding such an installation of an ultrasonic transducer 10 in the bumper of a motor vehicle, reference is made to document DE 10 2005 045 019 A1 of the applicant, which is to that extent to be part of this application.

[0024] Ultrasonic transducer 10 has a transducer housing 11 normally made of several components, which forms a diaphragm element 12 in the area of an end face of ultrasonic transducer 10. Transducer housing 10 and in particular diaphragm element 12 are normally made of metal, for example of aluminum, and are produced at least in part by deep drawing. Diaphragm element 12 is developed to transmit and to receive oscillations in the direction of double arrow 13 that runs perpendicularly with respect to the plane of the diaphragm. This operating state represents a first operating mode of ultrasonic transducer 10. The oscillatory ability concerns both the emission of sonic waves in the ultrasonic range as well as the excitation of diaphragm element 12 by sonic waves in the ultrasonic range acting on diaphragm element 12 from outside. The ultrasonic transducer 10 is operated in such a way that by turns sonic pulses are transmitted within a certain time window and subsequently sonic waves are able to be received during a waiting period in order to infer a distance of an object from ultrasonic transducer 10 from the duration between the transmitted and the received sonic waves.

[0025] Diaphragm element 12 is disposed in operative connection with a piezo element 15 both in order to produce such oscillations or sonic waves as well as to receive the same. Piezo element 15 is situated in interior 16 of transducer housing 11 and is connected to the side of diaphragm element 12 facing interior 16 preferably via an adhesive connection (not shown). Via electrical connection leads 17, 18, piezo element 15 is connected to a circuit substrate 20, normally in the form of a circuit board. Circuit substrate 20 is also located in interior 16 of transducer housing 11. Electronic components 21, 22 are situated on circuit substrate 20, the electronic components 21, 22 including in exemplary and non-restricting fashion a microcontroller, an ASIC (application-specific integrated circuit component), transmitting and receiving output stages as well as elements for detecting component temperatures such as heat sensors. The ultrasonic transducer 10 described so far is electrically contactable via a plug connector 23.

[0026] At temperatures below the freezing point, there is the danger that a coating 1, in particular in the form of icing, forms on the outside of diaphragm element 12 on the side facing away from the interior 16. Such a coating 1 changes the resonant behavior both of diaphragm element 12 as well as of piezo element 15 coupled with diaphragm element 12. To determine whether a coating 1 exists on diaphragm element 12, the present invention provides, in accordance with the representation in FIG. 2, for controlling piezo element 15 with different frequencies f and at the same time to measure the impedance I. The shape of the curve shown in FIG. 2 shows that there exists a relatively low impedance I at point A, while at points B the impedance I exhibits local maxima. Point A indicates the operating point of diaphragm element 12, at which the latter is in resonant frequency. At such a resonant frequency, the energy required for producing oscillations or waves is relatively low. On the other hand, at points B or the corresponding frequencies f, there is a lower efficiency factor due the relatively high impedance. That means that when diaphragm element 12 is controlled by piezo element 15 in the range of frequencies f of points B in a second operating mode the energy is converted with a relatively high component of heat loss. Such an increased heat loss results in a heating of interior 16 of transducer housing 11 and thus also in a melting of coating 1.

[0027] It is also possible to effect the increase of the temperature within transducer housing 11 in a second operating mode in that the electronic components 21, 22 are operated in the second operating mode in such a way that increased power losses occur.

[0028] FIG. 3 shows the operating method of the present invention for ultrasonic transducer 10: In a first step 101, diaphragm element 12 is checked to determine if it has a coating 1 using said impedance measurement according to FIG. 2. If the impedance measurement determines that the frequency f, at which the lowest impedance I occurs, is at a frequency f, which typically exists without coatings 1, then an inference is made from this fact that no coating 1 exists on diaphragm element 11. In a second step 102, ultrasonic transducer 10 is operated in the first operating mode that corresponds to the normal measurement operation.

[0029] If on the other hand the measurement determines the existence of a coating 1, then, according to step 103, the normal measurement operation, i.e. the first operating mode of ultrasonic transducer 10, is abandoned. Subsequently, a temperature measurement of the surroundings is performed in a step 104, which occurs for example by a temperature sensor that usually exists in a motor vehicle. If the measurement indicates that the temperature is higher than 0 C., then, in accordance with step 105, an inference is made that ultrasonic transducer 10 is defective. This derives from the fact that, in the presence of a temperature of more than 0 C., normally there cannot exist a coating 1. Corresponding warnings may be output to an operator or driver so that the latter is informed about the fact that ultrasonic transducer 10 is not available.

[0030] If the temperature of the surroundings is lower than 0 C., on the other hand, then ultrasonic transducer 10 is operated, in accordance with step 106, in the second operating mode, which causes said heating of the interior 16 of transducer housing 11. To verify the efficacy of the measures of the second operating mode, a check is subsequently performed again in accordance with first step 101 for the existence of a coating 1.

[0031] The ultrasonic transducer 10 described thus far as well as the operating methods (first and second operating mode) may be adapted or modified in various ways, without deviating from the idea of the present invention. Thus it is possible, for example, to forgo impedance measurements for detecting coatings 1 and to control the operation in the second operating mode solely on the basis of a detected outside temperature. It is then also possible to specify certain frequencies f or different frequencies controlled in succession in order to remove coatings 1 even without impedance measurement.