a. Field of the Invention
The invention relates to a device with a microphone and a speaker or transducer and processing means to process audio signals from the microphone and for the transducer. Electronic devices and mobile devices especially serve several user interfaces of which the touch screen has revolutionized the market in the past few years. Ultrasonic gesture control has the power to add another interface that fills in for use cases where the touch screen is not reliable. This holds true for medical environments as well as for outdoor use cases just to name two. The invention suggests a different signal processing of the ultrasonic sending and receiving signals in order not to produce audible artifacts.
b. Background Art
Ultrasonic sound is sound in frequencies above human audibility and starts about 16 kHz and covers the frequency range above. An ultrasonic transducer for gesture control can be any acoustic transducer capable of producing appropriate sound pressure level to calculate an object's position based on the reflected ultrasonic signals. State of the art ultrasonic transducers produce high sound pressure in or near their resonance frequency which is for example in the range of 30 kHz to 50 kHz.
As mobile devices already comprise a transducer and a microphone for audio frequencies, it is the aim to use this transducer to generate ultrasonic sound and to use this microphone to capture reflected ultrasonic sound for gesture control. State of the art solutions in sonar technologies use a chirp signal as ultrasonic signal as shown in
First of all the overall spectrum of the ultrasonic signal needs to be taken into account.
Second, the high driving voltage can create highly stressed components which then exhibit nonlinear behavior. This in turn will produce nonlinear artifacts in the audible frequency area.
The problem of audible artefacts does not occur with ultrasonic transducers optimized for ultrasonic frequencies as they have their resonance frequency in the ultrasonic frequency area and only poor sound pressure in the human audible sound frequency area.
The problem arises to find a way to use the transducer of a mobile device optimized for audible sound frequencies as transducer for ultrasonic sound to enable gesture control without the drawback of audible artifacts.
It is an objective of the invention to solve the problem of audible artifacts when using the transducer of a mobile device for gesture control. A new mobile device comprises improved processing means to use a noise signal as ultrasonic signal. Due to a low crest factor of the noise signal, processing of the noise signal does not generate distortion and nonlinear artefacts in the audible frequency area. The inventive processing means furthermore continuously adapt the filter length to calculate the correlation between sent and received ultrasonic sound for better gesture control as explained below with the embodiments of the invention.
The foregoing and other aspects, features, details, utilities, and advantages of the present invention will be apparent from reading the following description and claims, and from reviewing the accompanying drawings.
Further embodiments of the invention are indicated in the figures and in the dependent claims. The invention will now be explained in detail by the drawings. In the drawings:
Various embodiments are described herein to various apparatuses. Numerous specific details are set forth to provide a thorough understanding of the overall structure, function, manufacture, and use of the embodiments as described in the specification and illustrated in the accompanying drawings. It will be understood by those skilled in the art, however, that the embodiments may be practiced without such specific details. In other instances, well-known operations, components, and elements have not been described in detail so as not to obscure the embodiments described in the specification. Those of ordinary skill in the art will understand that the embodiments described and illustrated herein are non-limiting examples, and thus it can be appreciated that the specific structural and functional details disclosed herein may be representative and do not necessarily limit the scope of the embodiments, the scope of which is defined solely by the appended claims.
Reference throughout the specification to “various embodiments,” “some embodiments,” “one embodiment,” or “an embodiment,” or the like, means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in various embodiments,” “in some embodiments,” “in one embodiment,” or “in an embodiment,” or the like, in places throughout the specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Thus, the particular features, structures, or characteristics illustrated or described in connection with one embodiment may be combined, in whole or in part, with the features, structures, or characteristics of one or more other embodiments without limitation given that such combination is not illogical or non-functional.
It is known technology to detect the distance and/or movement of an object by calculating the runtime difference between the ultrasonic signal 5 and the captured ultrasonic signal 9. This is realized by correlating these two signals and detecting a peak P within a resulting signal as can be seen in
Inventive processing means 4 are built to generate or read-out from a memory ultrasonic signal 5 with a signal form of a noise signal as shown in
As can be seen from
If unwanted noise would further increase due to a bad reflection scenario the system would end up with a SNR of −12 dB, which means, that processing means 4 get four times more unwanted noise than the wanted captured ultrasonic signal 9. To cope with such bad signal conditions the inventive processing means 4 update the filter length in order to pick more correlation features out of the captured ultrasonic signal 9 as can be seen from the example in
This is based on the principle that the filter length or length of the fixed noise signal used as ultrasonic signal 5 has to be increased if a weaker captured ultrasonic signal 9 is received covered with more noise what still enables good gesture detection results in bad reflection scenarios. On the other hand processor means 4 reduce the filter length or length of the fixed noise signal used as ultrasonic signal 5 if a stronger captured ultrasonic signal 9 is received covered with less noise what enables a more reactive and time wise accurate gesture control.
Using a fixed noise signal as ultrasonic signal yields three major advantages:
In closing, it should be noted that the invention is not limited to the above mentioned embodiments and exemplary working examples. Further developments, modifications and combinations are also within the scope of the patent claims and are placed in the possession of the person skilled in the art from the above disclosure. Accordingly, the techniques and structures described and illustrated herein should be understood to be illustrative and exemplary, and not limiting upon the scope of the present invention. The scope of the present invention is defined by the appended claims, including known equivalents and unforeseeable equivalents at the time of filing of this application.
Number | Date | Country | |
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62236744 | Oct 2015 | US |