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DE-102024210876-A1 - Sound detector and vehicle

DE102024210876A1DE 102024210876 A1DE102024210876 A1DE 102024210876A1DE-102024210876-A1

Abstract

The present invention relates to a sound detector (5) and a vehicle, wherein the sound detector (5) comprises a first laser diode (10), a second laser diode (15), a first interference detector (20), a second interference detector (25), and a sound receiving surface (30) comprising at least a first diaphragm (40) and a second diaphragm (45). The first diaphragm (40) and the second diaphragm (45) are configured to be set into vibration substantially independently of one another based on sound waves incident on the sound receiving surface (30) from the environment (7) of the sound detector (5). The first laser diode (10) is configured to illuminate the first diaphragm (40) on a side facing away from the environment (7) with a first laser light (50), while the second laser diode (15) is configured to illuminate the second diaphragm (45) on a side facing away from the environment (7) with a second laser light (55). The first interference detector (20) is set up to generate a first electrical signal (S1) based on interference from the first laser light (50) and from components of the first laser light (50) which are reflected at the first membrane (40), while the second interference detector (25) is set up to generate a second electrical signal (S2) based on interference from the second laser light (55) and from components of the second laser light (55) which are reflected at the second membrane (45).

Inventors

  • Sylvio Salomon
  • Andre Gerlach
  • Marko Liebler

Assignees

  • Robert Bosch Gesellschaft mit beschränkter Haftung

Dates

Publication Date
20260513
Application Date
20241113

Claims (10)

  1. a sound detector (5) comprising: - a first laser diode (10), - a second laser diode (15), - a first interference detector (20), - a second interference detector (25), and - a sound receiving surface (30) comprising at least a first diaphragm (40) and a second diaphragm (45), wherein: - the first diaphragm (40) and the second diaphragm (45) are configured to be set into vibration essentially independently of one another by sound waves, in particular ultrasonic waves, incident on the sound receiving surface (30) from the environment (7) of the sound detector (5), - the first laser diode (10) is configured to illuminate the first diaphragm (40) on a side facing away from the environment (7) with a first laser light (50), - the second laser diode (15) is configured to illuminate the second diaphragm (45) on a side facing away from the environment (7) with a second laser light (55), - the first Interference detector (20) is configured to generate a first electrical signal (S1), representing a vibration of the first membrane (40), based on interference from the first laser light (50) emitted by the first laser diode (10) and from components of the first laser light (50) reflected by the first membrane (40), and the second interference detector (25) is configured to generate a second electrical signal (S2), representing a vibration of the second membrane (45), based on interference from the second laser light (55) emitted by the second laser diode (15) and from components of the second laser light (55) reflected by the second membrane (45).
  2. sound detector (5) according to Claim 1 , wherein - the first laser diode (10) and/or the second laser diode (20) are configured as a self-mixing laser feedback interferometer, and/or - the first interference detector (20) and/or the second interference detector (25) are configured as photodiodes, which are in particular integrally configured with the first laser diode (10) and/or the second laser diode (15).
  3. Sound detector (5) according to one of the preceding claims, wherein - the first interference detector (20) is implemented based on the first laser diode (10) and the sound detector (5) is configured to generate the first electrical signal (S1) based on the effect of interference on a voltage drop across the first laser diode (10), and/or - the second interference detector (25) is implemented based on the second laser diode (15) and the sound detector (5) is configured to generate the second electrical signal (S2) based on the effect of interference on a voltage drop across the second laser diode (15).
  4. Sound detector (5) according to one of the preceding claims, wherein - the first laser diode (10) and the second laser diode (15) are the same laser diode (10), - the first interference detector (20) and the second interference detector (25) are the same interference detector (20), - the first laser light (50) and the second laser light (55) are the same laser light (50), and - the sound detector (5) is configured to detect vibrations of the first diaphragm (40) and the second diaphragm (45) alternately based on the laser light (50) of the laser diode (10) and the interference detector (20).
  5. sound detector (5) according to Claim 4 , wherein - the sound receiving surface (30) also has at least a third membrane, and - the sound detector (5) is configured to detect vibrations of the first membrane (40), the second membrane (45) and the third membrane alternately on the basis of the laser diode (10) and the interference detector (20).
  6. sound detector (5) according to Claim 4 or 5 , wherein the sound detector (5) is configured to alternately detect vibrations of respective membranes (40, 45) of the sound receiving surface (30) by arranging an optical switching unit (60, 65) between the laser diode (10, 15), which is provided for irradiating a plurality of membranes (40, 45), and the respective membranes (40, 45), wherein the switching units (60, 65) are configured, based on a respective control signal from the sound detector (5), to transmit the laser light (50, 55) generated by the laser diode (10, 15) alternately to one of the membranes (40, 45) at a time and to block the transmission to the other membranes (40, 45) during this period, and/or a movable optical element (70), in particular a lens and/or a mirror, wherein the movable optical element (70) is configured, based on a control signal from the sound detector (5) is to redirect the laser light (50, 55) emitted by the laser diode (10, 15) alternately onto one of the membranes (40, 45) based on an adjustment of the orientation of the movable optical element (70), and/or - each membrane (40, 45) has a liquid crystal layer (80, 85) on one side of the membranes (40, 45) facing the laser diode (10, 15), wherein the liquid crystal layers (80, 85) are set up on the basis of a respective control by the sound detector (5) to transmit the laser light (50, 55) generated by the laser diode (10, 15) alternately to one of the membranes (40, 45) and to block the transmission to the other membranes (40, 5) during this period.
  7. Sound detector (5) according to one of the preceding claims, wherein the sound detector (5) is configured to deflect and/or guide and/or split and/or combine the laser light (50, 55) between respective laser diodes (10, 15) and respective membranes (40, 45) corresponding to the laser diodes (10, 15) on the basis of statically arranged - mirrors (90, 95), and/or - lenses, and/or - optical waveguides, and/or - prisms.
  8. Sound detector (5) according to one of the preceding claims, wherein respective laser diodes (10, 15) and/or interference detectors (20, 25) of the sound detector (5) - are arranged with their respective corresponding membranes (40, 45) in a common housing (100), or - are arranged outside a housing (100) having the respective corresponding membranes (40, 45).
  9. Vehicle comprising at least one sound detector (5) according to one of the preceding claims, wherein the vehicle is equipped to detect objects in the vicinity (7) of the vehicle on the basis of the electrical signals (S1, S2) generated by the sound detector (5).
  10. Vehicle after Claim 9 , wherein the respective membranes (40, 45) of the sound receiving surface (30) of the sound detector (5) are integrated into a surface (110) of the vehicle facing the environment (7) of the vehicle.

Description

State of the art The present invention relates to a sound detector, in particular an ultrasound detector, and a vehicle with such a sound detector. Acoustic detectors, particularly ultrasonic detectors, are known from the prior art and are used, for example, to determine the distance to objects in the vicinity of a vehicle. Such prior art ultrasonic sensors are typically active sensors that operate on the pulse-echo principle and usually use an acoustic frequency range of 40 kHz to 60 kHz. These ultrasonic sensors measure the travel time of an emitted sound until it reaches its destination. Return to the ultrasonic sensor to determine the distance to a backscattering object based on the known speed of sound propagation. Ultrasonic sensors can be divided into those that have a single transducer element and are referred to here as single sensors, and those that have more than one transducer element, whereby these multiple transducer elements are usually arranged close together within the ultrasonic sensors and are referred to here as array sensors. Such array sensors, due to their spatial scanning capability, are able to determine the direction of reception of an incident sound, in addition to time-of-flight analysis and thus distance determination (as with a single sensor). This additional directional information makes it possible to determine the three-dimensional location of the sound backscattering origin and thus the location of objects in the vehicle's vicinity. Besides the piezoelectric transducer principle, other transducer principles are known from the prior art for detecting the displacement of a diaphragm during sound reception. For example, laser feedback interferometry (LFI), which is based on the effect of self-mixing interferometry (SMI), can be used. This is described, among other places, in the following publications. Thomas Taimre, Milan Nikolić, Karl Bertling, Yah Leng Lim, Thierry Bosch, and Aleksandar D. Rakić, “Laser feedback interferometry: a tutorial on the self-mixing effect for coherent sensing,” Adv. Opt. Photon. 7, 570-631 (2015 ) Silvano Donati, “Vibration Measurements by Self-Mixing Interferometry: An Overview of Configurations and Benchmark Performances,” Vibration 6, 625-644 (2023 ) Disclosure of the invention According to a first aspect of the present invention, a sound detector and in particular an ultrasonic sensor is proposed, which comprises a first laser diode, a second laser diode, a first interference detector, a second interference detector and a sound receiving surface, wherein the sound receiving surface has at least a first membrane and a second membrane. It should be noted that the sound detector can preferably be designed as a sensor for a vehicle, which, due to its size and/or geometry and/or mounting devices, is designed for installation in a vehicle and can be used in particular as an environmental sensor for such a vehicle. This explicitly does not preclude the sound detector according to the invention from also being used outside the vehicle context. The sound detector is, for example, constructed as a pot-shaped structure with the sound receiving surface located on its front face. Preferably, the sound receiving surface is smooth and closed towards the surroundings of the sound detector. The sound receiving surface, in particular its inner side (i.e., a side facing away from the surroundings), has, for example, a structure that forms the basis for the first and second diaphragms. This structure can, for example, include stiffeners between the diaphragms and/or at the edges of the diaphragms to reduce or minimize mechanical crosstalk between them. The first and second diaphragms are configured to be set into vibration essentially independently of each other by sound waves, particularly ultrasound waves, incident on the sound receiving surface from the vicinity of the sound detector. "Essentially independent" means that, by their very nature, the first and second diaphragms cannot provide perfect mechanical decoupling and therefore cannot vibrate completely independently of each other. However, the mechanical decoupling is preferably designed such that unwanted vibrations are prevented. The vibration of one membrane by a vibration of the other membrane can be reliably distinguished from vibration excitation by sound waves striking the respective membranes. It should also be noted that the generation of the respective sound waves, which are detectable by the sound detector according to the invention, can take place both independently of and/or based on the sound detector according to the invention. Generating the sound waves independently of the sound detector according to the invention is a preferred embodiment, since in this variant no additional electromechanical transducer (e.g., a piezoelectric transducer) needs to be integrated into the sound detector according to the invention, which allows the size of the sound detector and/or the manufacturing costs of