Method for dirt detection and cleaning with piezo transducer, device, motor vehicle part and vehicle

Abstract

The present disclosure relates to a method for detecting dirt and cleaning a surface of a camera device (10, 10'), in particular a lens system (13, 13') or a lens cover (14) of the camera device (10, 10'), with at least one piezoelectric transducer (40, 40') mechanically coupled to this surface, the method comprising the following steps: a) activating the at least one piezo transducer (40, 40') for dirt removal by vibration, and b) determining the result of the dirt removal in step a) using a mass resonance measurement method, and c.1) either repeating the sequence of steps a) and b) if the determined mass has not changed and / or discontinuing the procedure if the determined mass has fallen below a first threshold value, c.2a) or performing a method for detecting an optical blockage if the mass determined in step b) is above a second threshold value, and c.2b) if an optical blockage in the field of view of the camera device is detected in step c.2a), initiating at least one countermeasure, or, if no optical blockage in the field of view of the camera device is detected in step c.2a), discontinuing the method. It also relates to a device for carrying out this method and to a motor vehicle part comprising such a device.

Description

[0001] The present disclosure relates to a method for detecting dirt and cleaning a surface of a camera device, comprising at least one piezoelectric transducer mechanically coupled to this surface, as well as to a device for implementing this method. Both the method and the device are suitable for use with a driver assistance system, preferably for an autonomously driving vehicle. Furthermore, the present disclosure relates to a motor vehicle part comprising this device and a vehicle comprising such a motor vehicle part.

[0002] Conventional cleaning systems in vehicles use water. For example, an exterior rearview device is known from US 2023 / 017426 A1, which comprises a base assembly configured to be mounted on a vehicle to movably support a head assembly of the exterior rearview device, the base assembly including a camera with a lens; a cleaning system with a nozzle for dispensing a cleaning fluid such as water onto the lens; a base frame; a base cover including a plurality of cover pieces providing a first opening for the lens and a second opening for the nozzle; and a camera mount attached to the base frame to hold both the camera and the nozzle.

[0003] Since the water must be stored in containers within the vehicle, it must be refilled at regular intervals. This is time-consuming. Other cleaning methods that avoid the use of water are also known from the prior art. US 2018 / 154406 A1 discloses a lens cleaning system with foreign material detection. This lens cleaning system uses a transducer mechanically coupled to a lens, a driver to provide an oscillating drive signal to the transducer, and a controller to control the drive signal frequency so that the lens vibrates at frequencies within a range of interest.The controller determines a measured resonant frequency of the lens cleaning system in the region of interest according to a transducer feedback signal and selectively performs a lens cleaning operation when the measured resonant frequency deviates from a baseline resonant frequency of the lens cleaning system for a clean lens.

[0004] A system such as the perception system of an autonomous vehicle of US 2023 / 068848 A1 identifies and classifies an obstacle in a field of view of an image capture device. The system receives a sequence of individual images from the image capture device. For each individual image, the system segments the individual image into regions of interest (ROIs), and the system uses a classifier to assign a classification to each ROI. The classification indicates whether the ROI is clear or blocked. The system summarizes the classifications for each ROI to determine an overall classification. If a blocked classification exists for a certain number of individual images, the system classifies the image capture device as blocked and generates a function request that, when executed, causes a system of which the image capture device is a component to perform a function.

[0005] US 2023 / 145395 A1 relates to a method for cleaning a protective device for a driver assistance system comprising an optical sensor with an optic, wherein the protective device has an optical element arranged upstream of the optic, which optical element has an inner surface and an outer surface and is mounted so as to be movable about an axis of rotation, the method comprising the following steps: processing a sequence of images taken by the optical sensor as the optical element rotates to detect a generally circular or semicircular shape centered on the axis of rotation of the optical element and created by dirt deposited on the outer surface, and triggering at least one action for cleaning the outer surface of the optical element when the shape is detected.

[0006] Without the use of water, cleaning is often not satisfactory, especially with dry dirt.

[0007] It is therefore the aim of the present invention to provide a method for dirt detection and cleaning with at least one piezo transducer which overcomes the disadvantages of the prior art.

[0008] This aim is achieved by a method for detecting dirt and cleaning a surface of a camera device, in particular a lens system or a lens cover of the camera device, with at least one piezo transducer mechanically coupled to this surface, wherein the method comprises the following steps: a) activating the at least one piezo transducer for removing dirt by vibrations, and b) determining the result of the dirt removal in step a) using a mass resonance measuring method, and c.1) either repeating the sequence of steps a) and b) if the determined mass has not changed, and / or discontinuing the method if the determined mass has fallen below a first threshold value, c.2a) or carrying out a method for detecting optical blockages if the mass determined in step b) is above a second threshold value, and c.2b) if in step c.2a) an optical blockage is detected in the field of view of the camera device, initiating at least one countermeasure, or, if in step c.2a) no optical blockage is detected in the field of view of the camera device, discontinuing the method.

[0009] According to the present disclosure, it is proposed that the at least one piezo transducer is activated at least partially during the implementation of the mass resonance measurement method in order to cause dirt particles to migrate and / or burst.

[0010] Embodiments of the present disclosure may be characterized in that the at least one piezo transducer can be controlled at different frequencies, the mass resonance measuring method can be controlled at different frequencies and / or the drive signal frequency of the at least one piezo transducer differs from the frequency used in the mass resonance measuring method.

[0011] It is further proposed that a baseline resonance frequency measured for the clean surface using the mass resonance measurement method be compared with the frequency measured at each step of performing the mass resonance method to determine the mass or mass change of dirt.

[0012] It is further proposed that the at least one piezo transducer is activated at least partially during the implementation of the method for detecting an optical blockage in order to determine a movement of an optical blockage relative to an unchanged background, in particular with a low frequency of the at least one piezo transducer, and / or a change in the shape of an optical blockage upon the onset of a vibration compared to a non-vibrating state, in particular with a high frequency of the at least one piezo transducer.

[0013] In this context, it is also proposed that the at least one piezo transducer can be controlled at different frequencies, the method for detecting optical blockages can be controlled at different frequencies and / or the drive signal frequency of the at least one piezo transducer differs from the frequency used in the method for detecting optical blockages.

[0014] According to the present disclosure, it is proposed that step a) is initiated if an initial dirt mass detection via the mass resonance measurement method determines a mass above a third threshold, upon activating the camera device, upon approaching a vehicle with the camera device with a key, upon starting the vehicle with the camera device, after a preset time interval has elapsed, at a specific time, or manually.

[0015] It is also proposed that the at least one countermeasure comprises the output of a signal, in particular in the form of a message for dirt removal, the activation of at least one air valve for dirt removal, the activation of at least one mechanical cleaning device, which in particular comprises a wiper and / or is provided by a key, and / or the activation of at least one water valve for dirt removal.

[0016] It is further proposed that the type of countermeasure(s), the quantity of countermeasures and / or the sequence of countermeasures depend(s) on the mass and / or the mass change determined by at least one of the steps of performing the mass resonance measurement method and / or the blocked optical flow, the amount of visible dirt, the amount and / or size of blocked pixels of an image area, the resolution of the image area and / or an area monitored by the camera device.

[0017] Embodiments may be characterized in that the activation of the at least one water valve is the last selected countermeasure in a sequence of countermeasures.

[0018] According to a further aspect, it is proposed that after the at least one countermeasure, the at least one piezo transducer is activated, a further resonance mass measurement method is carried out and / or a further method for detecting optical blockages is carried out.

[0019] The present disclosure also provides a device for detecting dirt and cleaning a surface of a camera device, in particular a lens system or a lens cover of the camera device, with at least one piezo transducer mechanically coupled to this surface, wherein the device is suitable for carrying out the method according to the present disclosure.

[0020] The device according to the present disclosure may comprise ultrasonic surface cleaning electronics with at least one configurable digital signal processor, a piezo driver connected to the at least one piezo transducer of the camera device, at least one power supply pin, and an evaluation module.

[0021] It is proposed that the ultrasonic surface cleaning electronics comprise a pulse width generator and a pulse width controller and / or at least one sensor, which in particular comprises a current sensor, a voltage sensor and / or a temperature sensor.

[0022] It is further proposed that the camera device comprises a housing, a printed circuit board with at least one optical sensor, a lens cover, the lens system and the piezo transducer in mechanical connection with the lens cover and arranged within the housing.

[0023] It is further proposed that the lens system is arranged between the lens cover and the printed circuit board or comprises the lens cover.

[0024] According to one aspect of the present disclosure, the piezo transducer has a ring shape and / or at least partially encloses the lens system.

[0025] According to a further aspect, the housing is formed with a recess, wherein the lens cover and the piezo transducer extend into the recess, wherein preferably an elastic sealing means is arranged between the housing and the lens cover.

[0026] The present disclosure also provides a motor vehicle part, in particular in the form of a rear-view device and / or driver assistance device of a motor vehicle, with at least one device according to the present disclosure.

[0027] Finally, the present disclosure also provides a vehicle, in particular an autonomously driving vehicle, with a motor vehicle part according to the present disclosure.

[0028] It is proposed that at least one vehicle sensor output and / or driving data control the piezo transducer vibration, the mass resonance measurement method and / or the optical blockage detection method.

[0029] The present disclosure thus provides optimal means for detecting dirt and cleaning a surface of a camera device, in particular a lens system or a lens cover, with minimal water consumption. This is because one or more piezo transducers are used to remove dirt particles, as well as ice and condensation, through vibration. Furthermore, the vibrations can also lead to targeted droplet migration, particularly in a mass resonance measurement method for determining a mass or mass change of dirt. Even further, vibrations can be used to detect an optical blockage even when the camera device is stationary. Air from air nozzles can be used for loose, dry dirt, and water from water nozzles can only be used as a last resort to remove residual dirt.

[0030] The minimum particle size, especially the dirt or droplet size, that can be determined depends on the resolution of the camera device. The piezo transducer(s) can only be activated when the particles have reached or exceeded this minimum size.

[0031] The foregoing summary, as well as the following detailed description, will be better understood when read in conjunction with the accompanying drawings. For purposes of illustration, certain examples of the present disclosure are shown in the drawings. It should be understood, however, that the present disclosure is not limited to the exact arrangements and instrumentalities shown. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one implementation of systems, devices, and methods according to the present disclosure and, together with the detailed description, serve to explain advantages and principles according to the present disclosure, wherein: Fig. 1 is a schematic representation of a dirt detection and cleaning device according to the present disclosure having ultrasonic lens cleaning electronics connected to a camera device; Fig. 2 is a perspective view of a camera device for a motor vehicle part according to the present disclosure; and Fig. 3 is a flowchart of a method for dirt detection and cleaning according to the present disclosure.

[0032] A device for dirt detection and cleaning according to the present disclosure with an ultrasonic lens cleaning electronics 100 connected to a camera device 10 is shown in Fig. 1. The ultrasonic lens cleaning electronics 100 may include a configurable digital signal processor (DSP) 101 for ultrasonic lens cleaning with current and voltage monitoring and pulse width modulation (PWM), such as the commercially available ULC1001 from Texas Instruments. The ULC1001 is a configurable PWM modulator with current and voltage monitoring functions specifically for piezo-based lens cleaning systems. Furthermore, the ultrasonic lens cleaning electronics 100 may include a piezo driver 102 such as the DRV2901 and an evaluation module (EVM), in particular in the form of the so-called ULC1001-DRV290XEVM, which is an evaluation module (EVM) that represents a two-chip solution comprising the ULC1001 and the DRV2901.The two can work together to provide self-cleaning functionality with features such as temperature detection, lens defect detection, and contaminant detection for automatic cleaning.

[0033] A power supply pin 103, such as a PVDD, is connected to the piezo driver 102. The DSP 101 is connected to a printed circuit board (PCB) 11 of the camera device 10 via the piezo driver 102 and filter 105. Furthermore, the DSP 101 is connected to the PCB 11 via resistor dividers 104.

[0034] The camera device 10 comprises, in addition to the PCB 11, a PD 12, which is an image sensor and is arranged on the PCB 11, and a lens system 13 arranged above the PD 12 in a housing 20 that is covered with a lens cover 14 and sealed by a seal 30. The lens cover 14 can be part of the lens system 13 or provided separately. The housing 20 is formed with a recess 21 for attaching the lens cover 14, the seal 30, and a piezo transducer 40 below the lens cover 14 and in mechanical contact therewith, and is designed to at least partially surround the lens system 13. The piezo transducer 40 is connected to the PCB 11 via cables 41, 42. The camera device 10 can have a circular cross-section, so that the piezo transducer 13 can be in the form of a ring.

[0035] Fig. Figure 2 illustrates a camera device 10' with cables 41', 42' leading to ultrasonic lens cleaning electronics (not shown). The camera device 10' includes a lens system 13' and a piezoelectric transducer 40' beneath a lens cover and within a housing 20'. Furthermore, the camera device 10' can be configured to be installed in a motor vehicle component such as a rearview mirror or other camera monitoring system, with the lens cover of the camera device being installed on the exterior of a vehicle and the monitor being installed inside the vehicle.

[0036] Like all camera-based systems used outdoors, the camera device 10' also has the problem of quickly becoming dirty. Furthermore, icing, fogging, and the like can block the view through the lens system 13' below the lens cover in a similar manner to dirt, all of which are referred to as "dirt" in this disclosure. Mass resonance measurements can be used to determine whether dirt is trapped on the lens cover. Since this measures the entire cover lens, false positive results can occur because blockages that are not within the field of view (FoV) are also detected.

[0037] The piezo transducer 40' can be activated to remove dirt, where, for example, ice takes longer to remove than fog or water droplets. A mass resonance measurement can be used after activating the piezo transducer 40' to detect whether the lens cover is optically blocked and / or whether a cleaning cycle was successful. If it is then determined that the mass has changed compared to the last cycle—i.e., dirt has been removed but the original mass before the blockage has not yet been reached—optical blockage detection can be performed.

[0038] Optical blockage detection allows for a visual check to determine whether there are any remaining blockages on the lens cover within the field of view. The 40' piezo transducer can also be activated during detection to improve the detection of optical blockages, as water droplets are moved by vibrations, allowing them to be more easily detected and removed immediately.

[0039] To remove dirt such as the Fig. 1 on the lens cover 14, a mass detection is performed. The mass detection can be performed in the form of a mass resonance measurement, in which the detection of a resonance frequency RF is used via voltage measurements, with RF=√(k / m'), where m defines an initial mass, m' is the initial mass plus dirt (m' = m + dirt) and k is the stiffness or spring constant of the piezo transducer 40 with the lens cover 14.

[0040] If the measured resonance frequency RF is equal to the initial resonance frequency RFo of a clean lens cover 14, m = m', ie there is no dirt on the lens cover 14. However, if there is a change in the measured resonance frequency RF, m ≠ m', ie there is additional mass, so the lens cover 14 is presumably dirty or wet.

[0041] Optical blockage detection can be performed by determining optical flow. One possibility is to detect static regions while the camera device 10 is moving, since static regions are created by dirt deposited on the lens cover 14. If the camera device 10 is installed on the exterior of a vehicle, the movement required for optical blockage detection is present when the vehicle has a speed v greater than zero (v > 0).

[0042] Another way to detect an optical blockage caused by dirt on the lens cover 14 is to use the movement or, better, vibration generated by the piezoelectric transducer 40 without the vehicle having to move, i.e. with v = 0. In this context, two aspects must be considered: • Movement of an optical block relative to a stationary background can be detected when vibration, particularly at a low frequency, is applied. • A change in the shape of an optical blockage can be detected when vibration is applied, compared to a non-vibrating condition. For example, at high frequencies, water droplets are stretched because the amplitude can be added by the rapid movement of the lens cover.

[0043] For example, with a pixel size of 3 µm on an imager and a piezo amplitude of approximately 50 µm, a dirt particle with a cross-section of 30 µm that causes an optical blockage of 10 pixels moves by 50 µm. Since the imager's exposure is much smaller than the oscillation frequency of the piezo transducer, the dirt particle is perceived as having a diameter of approximately 80 µm.

[0044] In the static area, i.e. when the vehicle is moving, other algorithms can also be used, such as AI approaches.

[0045] Both detection methods described above require no additional hardware, but can be integrated into existing hardware purely through software. On the one hand, mass resonance measurements are part of a piezo transducer control system. On the other hand, optical blockage detection is part of a camera control unit.

[0046] If dirt is detected via optical blockage detection after a mass resonance measurement, the decision as to when to initiate cleaning may depend on the number of pixels on the imager blocked by dirt. The respective threshold can therefore vary from application to application and is customer-specific.

[0047] Several examples of a dirt detection and cleaning process are described below: Example 1: Blockage present in the FoV

[0048] If a blockage is detected in the FoV of the camera device that cannot be removed by activating the piezo transducer 40', various countermeasures can be initiated alternatively or sequentially, whereby the sequence can in principle vary, except that water cleaning is preferably the last option: • Repeat the activation of the piezo transducer. • Display a message to remove dirt. • Activate an air valve, if available. • Activate a wiper, if available. • Activate a water valve, if available. Example 2: No blockage detected in the FoV

[0049] Even if no blockage is detected in the FoV, it may still be the case that the entire lens cover is blocked, or that the system cannot determine the situation, for example, due to poor contrast and poor lighting conditions when viewing a white wall, which may appear due to fog. The procedure to determine this is to test the optical flow by examining pixel movement, with the following two consequences: • If no optical flow is present, countermeasures are initiated analogous to those described in Example 1. • If sufficient optical flow is present, the program is terminated. Example 3: Dirt test on a parked car

[0050] There can be two different situations: • When a driver pulls a vehicle's key device, they can receive a signal or message to clean the lens cover if the lens cover is detected as dirty or after a certain period of time has elapsed. For cleaning purposes, the piezoelectric transducer 40' can be activated analogously to embodiment 1, or cleaning agents provided by the key device can be used. Regarding the latter, reference is made to the teaching of US 11,077,832 B2. • After entering the vehicle, a test cycle can be started by activating the piezo transducer to check the cleanliness of the camera lens cover, and then one or more messages or actions are initiated, e.g. as described for Example 1.

[0051] A method for dirt detection and cleaning 500 is described in Fig. 3, which includes the following steps: • In a first step 510, the piezo transducer is activated to remove dirt. • Then, in a second step 520, a mass check is carried out, for example via a mass resonance measurement, to check whether there is still dirt on the lens cover. • If it is determined in a third step 530 that the mass has not changed, the piezo transducer is reactivated by returning to the first step 510. However, if a change in the mass is detected, the process proceeds to a fourth step 540. • If no additional mass is detected in the fourth step 540, the method is terminated by proceeding to the last step 590. However, if an additional mass is detected, the method proceeds to a fifth step 550. • In the fifth step 550, optical blockage detection is performed. • In a sixth step 560, it is determined whether a blockage exists within the FoV. • If it is determined that an optical blockage exists within the FoV, the method proceeds to a seventh step 570 to initiate one or more countermeasures as described in Example 1. For example, the method may return to the first step 510 to initiate a vibration. However, if no countermeasures are to be initiated, the method continues to an eighth step 580 to check for optical flow. It may be determined that optical flow is disturbed if static pixel areas on the imager are larger than a specific threshold. This threshold depends on the resolution of the imager and the aperture angle of the lens. • If it is determined in the seventh step 560 that there is no optical blockage within the FoV, the method also continues with the eighth step 580. • If no optical flow is detected in the eighth step 580, the method proceeds to the seventh step 570 to initiate a countermeasure as explained in Example 1; however, if optical flow is detected in the eighth step 580, the method proceeds to the last, ninth step 590, which represents the end.

[0052] The with reference to Fig. The method described in section 3 can be used to distinguish between fog, mist, fly debris, droplets, and ice on the lens cover. The method allows for the detection of a minimal mass change of 0.014 g and a size of, for example, a droplet with a diameter of approximately 0.3 mm, depending on the camera resolution. Dirt with a mass of less than 0.014 g and a diameter of less than 0.3 mm does not impair the function of the camera device because it is not visible to the camera device. These dimensions cover typical dirt particles dissolved in water, and a typical water droplet has a diameter of 0.5 mm. Due to this precise dirt detection and the various countermeasures to be taken, the amount of water required to clean a cover lens is minimized.

[0053] Here are some more examples of dirt detection and cleaning: A) Fog It is not possible to visually distinguish whether the fog is fogged or a misted lens. However, the use of a mass resonance measurement method and / or the activation of a piezoelectric transducer enables such a distinction. The mass resonance measurement method can distinguish between moisture and droplets. In the case of very light fogging, activating the piezoelectric transducer for 2 seconds is sufficient to remove the fog. If the contrast does not improve significantly during an image inspection after activating the piezoelectric transducer, it is assumed that the fog is present, and cleaning should be stopped or not initiated. The presence of fog can be verified through driving data such as speed and temperature measurements. B) Fly droppings The mass resonance measurement method allows for the detection of fly debris, but activating a piezoelectric cleaning system may not be successful in this case, as it can only remove wet debris. Activating the piezoelectric transducer while simultaneously monitoring the optical flow through the lens system with the cover lens provides information about the success of the vibration, and there are three possible outcomes: 1. The detected mass reaches its original value of a clean surface because the fly droppings have fallen off. 2. The detected mass decreases but does not return to the original value, or the mass remains the same. If the mass decreases, the optical flow may increase again. This means that if the dirt is partially removed by reducing the mass, the optical flow may return to the focus area. If the optical flow no longer detects any blockages, the residual dirt is smaller than 0.3 mm in diameter and therefore no longer needs to be considered. 3. The detected mass does not decrease, so a different cleaning method must be used, in which an air jet is activated before a water jet is activated. This means that after air cleaning, vibrations are applied and the optical flow is checked again, and a decision is made whether water should be used for further cleaning. If water is used, activation of the piezo transducer can be used to remove droplets. To save water, it is also possible to let the droplet travel directly to the location where the dirt was detected, allowing the dry dirt to be loosened before it is removed by vibration. D) Droplets A short pulse activating the piezoelectric transducer is sufficient to burst a droplet during a droplet ejection. Two droplet ejection methods can be used: drawing water to the center of the lens cap, where it can be burst with maximum energy, or pushing it out of the field of view so that it is no longer in the field of view. A combination of both methods can also be used, as dirty water droplets tend to leave their dirt on the lens cap after the droplet explodes, which can lead to dirt buildup. Furthermore, a large droplet can be split into many small droplets, making it undetectable. The water nozzle only needs to be activated if the dirt accumulation after the droplet explosion in the center becomes larger than 0.3 mm or the optical flow is blocked by an object. E) Ice The mass resonance measurement method can be used for ice detection, and the piezo transducer can be controlled at a different frequency, with a higher frequency than that used for droplets. The vibrations generated by the piezo transducer can convert ice into water and be removed in the same way as for droplet removal. For thick ice layers, the piezo transducer can be activated multiple times, e.g., up to three times. Droplet detection can be activated as part of the cycle after each cycle. The success of the removal can be verified using an optical flow algorithm and other measurements of the vehicle.

[0054] While the mass resonance measurement method involves an additional mass, which is the sum of all mass particles, for example on the Fig.1, the detection of blockages in the optical flow is more concerned with coherent dirt pixels that are actually visible in focus. For example, the sum of 20 very small particles can be classified as hazardous in a mass resonance measurement, even though, if they are all separate, they will not be detectable in the optical flow because they cannot be focused as individual points. The detection of optical blockages therefore makes it possible to detect a number of static pixels and determine this as the threshold for cleaning. The algorithm distinguishes between v = 0 vibration impact and v > 0 comparison between a moving background and a static foreground. In both methods, the size of the static pixel is determined and classified.

[0055] The size of the smallest detectable contaminants, e.g., in the form of dirt droplets, depends on the camera focus and must be calculated individually for different setups, each depending on the lens and resolution. If dirt droplets are just visible, cleaning with vibrations is sufficient. However, if dirt droplets are clearly visible, cleaning with water may be necessary. Relevant parameters when determining the cleaning method depend on the visible area of ​​dirt and the size of a pixel on the image converter, which are determined by the monitored area, particularly the distance to be monitored. If a camera needs to see up to 90 m, one pixel blocked by dirt can already be a lot, whereas in a surveillance system that only needs to monitor a few meters in front of a vehicle, a plurality of pixels may not be a lot.

[0056] It will be apparent to those skilled in the art that modifications could be made to the above-described embodiments without departing from the general spirit of the invention. Accordingly, it is to be understood that the invention disclosed herein is not limited to the specific embodiments disclosed and is intended to cover modifications that are within the scope and spirit of the present invention. Reference symbol 10, 10' camera device 11 printed circuit board 12 Partial discharge system 13, 13' lens system 14 Lens cover 20, 20' housing 21 Deepening 30 Seal 40, 40' piezo transducer 41, 41' cable 42, 42' cable 50 water droplets 100 ultrasonic lens cleaning electronics 101 configurable digital signal processor 102 piezo drivers 103 Power supply pin 104 resistor dividers 105 filters 500 methods for dirt detection and cleaning 510 to 590 process step QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 2023 / 017426 A1

[0002] US 2018 / 154406 A1

[0003] US 2023 / 068848 A1

[0004] US 2023 / 145395 A1

[0005] US 11,077,832 B2

[0050]

Claims

[1] Method for detecting dirt and cleaning a surface of a camera device (10, 10'), in particular a lens system (13, 13') or a lens cover (14) of the camera device (10, 10'), with at least one piezoelectric transducer (40, 40') mechanically coupled to this surface, the method comprising the following steps: a) activating the at least one piezo transducer (40, 40') for dirt removal by vibration, and b) Determining the result of the dirt removal in step a) using a mass resonance measurement method and c.1) either repeating the sequence of steps a) and b) if the determined mass has not changed and / or discontinuing the procedure if the determined mass has fallen below a first threshold value, c.2a) or performing a method for detecting an optical blockage if the mass determined in step b) is above a second threshold value, and c.2b) if an optical blockage in the field of view of the camera device is detected in step c.2a), initiating at least one countermeasure, or, if no optical blockage in the field of view of the camera device is detected in step c.2a), discontinuing the method. [2] Method according to claim 1, wherein the at least one piezo transducer (40, 40') is activated at least partially during the performance of the mass resonance measurement method in order to cause dirt particles to migrate and / or burst. [3] Method according to claim 1 or 2, wherein the at least one piezoelectric transducer (40, 40') can be controlled at different frequencies, the mass resonance measurement method can be controlled at different frequencies and / or the drive signal frequency of the at least one piezo transducer (40, 40') differs from the frequency used in the mass resonance measuring method. [4] A method according to any one of the preceding claims, wherein a baseline resonance frequency measured by the mass resonance measurement method for the clean surface is compared with the frequency measured in each step of performing the mass resonance method to determine the mass or mass change of dirt. [5] Method according to one of the preceding claims, wherein the at least one piezoelectric transducer (40, 40') is activated at least partially during the performance of the method for detecting an optical blockage in order to • a movement of an optical block relative to an unchanged background, in particular with a low frequency of the at least one piezo transducer (40, 40'), and / or • to determine a change in shape of an optical blockage upon the onset of a vibration compared to a non-vibrating state, in particular with a high frequency of the at least one piezo transducer (40, 40'). [6] Method according to claim 5, wherein the at least one piezoelectric transducer (40, 40') can be controlled at different frequencies, the optical blockage detection process can be controlled at different frequencies and / or the drive signal frequency of the at least one piezo transducer (40, 40') differs from the frequency used in the method for detecting optical blockages. [7] Method according to one of the preceding claims, wherein step a) is initiated, • if an initial dirt mass detection using the mass resonance measurement method determines a mass above a third threshold value, • when activating the camera device (10), • when approaching a vehicle with the camera device (10) with a key, • when starting the vehicle with the camera device (10), • after a preset time interval has elapsed, • at a specific time or • manually. [8] Method according to one of the preceding claims, wherein the at least one countermeasure • Emitting a signal, particularly in the form of a dirt removal message, • Activating at least one air valve to remove dirt, • Activating at least one mechanical cleaning device, which in particular comprises a wiper and / or is provided by a key, and / or • Activating at least one water valve to remove dirt. [9] Method according to claim 8, wherein the type of countermeasure(s), the set of countermeasures and / or the sequence of countermeasures of • the mass and / or the mass change determined by at least one of the steps of carrying out the mass resonance measurement method, and / or • the blocked optical flow, the amount of visible dirt, the amount and / or size of blocked pixels of an image area, the resolution of the image area and / or an area monitored by the camera device (10). [10] The method of claim 8 or 9, wherein the activation of the at least one water valve is the last selected countermeasure in a sequence of countermeasures. [11] Method according to one of the preceding claims, wherein after the at least one countermeasure, the at least one piezo transducer (40, 40') is activated, a further resonance mass measuring method is carried out and / or a further method for detecting an optical blockage is carried out. [12] Device for detecting dirt and cleaning a surface of a camera device (10, 10'), in particular a lens system (13, 13') or a lens cover (14) of the camera device (10, 10'), with at least one piezo transducer (40, 40') mechanically coupled to this surface, wherein the device is suitable for carrying out the method according to the present disclosure. [13] Device according to claim 12, comprising ultrasonic surface cleaning electronics (100) with at least one configurable digital signal processor (101), a piezo driver (102) connected to the at least one piezo transducer (40, 40') of the camera device (10, 10'), at least one power supply pin (103) and an evaluation module. [14] Device according to claim 13, wherein the ultrasonic surface cleaning electronics (100) comprises a pulse width generator and a pulse width controller and / or at least one sensor, which in particular comprises a current sensor, a voltage sensor and / or a temperature sensor. [15] Device according to one of claims 12 to 14, wherein the camera device (10, 10') comprises a housing (20, 20'), a printed circuit board (11) with at least one optical sensor (12), a lens cover (14), the lens system (13, 13') and the piezo transducer (40, 40') in mechanical connection with the lens cover (14) and arranged within the housing (20, 20'). [16] Device according to 15, wherein the lens system (13, 13') is arranged between the lens cover (14) and the printed circuit board (11) or comprises the lens cover (14). [17] Device according to one of claims 12 to 16, wherein the piezoelectric transducer (40, 40) has a ring shape and / or at least partially encloses the lens system (13, 13'). [18] Device according to one of claims 15 to 17, wherein the housing (20) is formed with a recess (21), wherein the lens cover (14) and the piezo transducer (40) extend into the recess (21), wherein preferably an elastic sealing means (30) is arranged between the housing (20) and the lens cover (14). [19] Motor vehicle part, in particular in the form of a rear-view device and / or driver assistance device of a motor vehicle, with at least one device according to one of claims 12 to 18. [20] Vehicle, in particular autonomously driving vehicle, with a motor vehicle part according to claim 19. [21] The vehicle of claim 20, wherein at least one of a vehicle sensor output and driving data controls the piezo transducer vibration, the mass resonance measurement method, and / or the optical blockage detection method.

Images