Ultrasonic lens cleaning system with current sensing

Patent metadata

Field	Value
Publication number	US-10401618-B2
Application number	US-201615059529-A
Country	US
Kind code	B2
Filing date	Mar 3, 2016
Priority date	Mar 11, 2015
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

Disclosed examples include ultrasonic cleaning systems, driver integrated circuits and methods for cleaning a lens, in which an oscillating drive signal is provided to an ultrasonic transducer and the driver controls the frequency of the drive signal according to a current sense signal representing a drive current flowing in the transducer. The driver sweeps the drive signal frequency and compares the sensed current values with predetermined profiles corresponding to a clean lens and a lens with one or more known contaminants, and generates the drive signal at one or more frequencies corresponding to peaks or valleys of the sensed current values or predetermined frequencies to promote cleaning of the lens.

First claim

The following is claimed:

1. An ultrasonic cleaning system, comprising:
a signal generator having a signal generator input and a signal generator output, the signal generator is configured to generate an output signal at the signal generator output, the output signal oscillating at a non-zero frequency according to a control signal at the signal generator input;
an amplifier having an amplifier input and an amplifier output, the amplifier input coupled to the signal generator output, the amplifier output adapted to be coupled to a transducer, the transducer adapted to be mechanically coupled to a lens and configured to vibrate the lens according to a drive signal, and the amplifier configured to generate the drive signal at the amplifier output by amplifying the output signal;
a current sense circuit having a current sense input and a current sense output, the current sense input adapted to be coupled to the transducer, and the current sense circuit configured to sense a drive current flowing in the transducer and to generate a current sense signal at the current sense output, the current sense signal representing the drive current; and
a control circuit having a control input and a control output, the control input coupled to the current sense output, the control output coupled to the signal generator input, and the control circuit configured to generate the control signal at the control output according to the current sense signal.

2. The system of claim 1 , wherein the amplifier has an amplifier control input, and the system further comprises a protection circuit having a protection circuit input and a protection circuit output, the protection circuit input coupled to the current sense output, the protection circuit output coupled to the amplifier control input, the protection circuit configured to generate a protection signal at the protection circuit output according to the current sense signal, and the amplifier configured to selectively adjust a gain of the amplifier according to the protection signal.

3. The system of claim 1 , wherein the control circuit is configured to: generate the control signal in a manner that causes the output signal to oscillate at a plurality of frequencies in a frequency range; and obtain a plurality of current signal values of the current sense signal respectively corresponding to the plurality of frequencies.

4. The system of claim 3 , wherein the control circuit is configured to:
compare a first profile corresponding to a clean lens to a second profile corresponding to the plurality of current signal values and the corresponding plurality of frequencies; and
if the first and second profiles are dissimilar;
identify one or more frequencies corresponding to local maxima or local minima of the plurality of current signal values; and
generate the control signal in a manner that causes the output signal to oscillate at one or more identified frequencies to promote cleaning of the lens.

5. The system of claim 4 , wherein the control circuit is configured to, after the control circuit generates the control signal in a manner that causes the output signal to oscillate at one or more identified frequencies to promote cleaning of the lens:
again generate the control signal in a manner that causes the output signal to oscillate at the plurality of frequencies in the frequency range;
obtain a further plurality of current signal values of the current sense signal respectively corresponding to the plurality of frequencies;
compare the first profile to a further profile corresponding to the further plurality of current signal values and the corresponding plurality of frequencies to determine whether further cleaning is needed; and
if the first and further profiles are dissimilar:
identify one or more further frequencies corresponding to local maxima or local minima of the further plurality of current signal values; and
generate the control signal in a manner that causes the output signal to oscillate at one or more of the identified further frequencies to promote cleaning of the lens.

6. The system of claim 3 , wherein the control circuit is configured to: compare a predetermined profile corresponding to a lens with a known contaminant and a second profile corresponding to the plurality of current signal values and the corresponding plurality of frequencies; and if the second profile is similar to the predetermined profile, generate the control signal in a manner that causes the output signal to oscillate at one or more predetermined frequencies to promote removal of the known contaminant from the lens.

7. The system of claim 3 , wherein the control circuit is configured to: store a plurality of predetermined profiles respectively corresponding to a lens with a corresponding known contaminant; compare the second profile and the plurality of predetermined profiles; and if the second profile is similar to a given set of the predetermined profiles, generate the control signal in a manner that causes the output signal to oscillate at one or more predetermined frequencies corresponding to each of the given set of the predetermined profiles to promote removal of the corresponding known contaminants from the lens.

8. The system of claim 7 , wherein the control circuit is configured to generate the control signal in a manner that causes the output signal to oscillate at two or more of the predetermined frequencies concurrently.

9. The system of claim 3 , wherein the control circuit is configured to generate the control signal in a manner that causes the non-zero frequency of the output signal to lock onto at least one resonance frequency according to the current sense signal.

10. The system of claim 1 , wherein the control circuit is configured to generate the control signal in a manner that causes the non-zero frequency of the output signal to lock onto at least one resonance frequency according to the current sense signal.

11. An integrated circuit (IC), comprising:
a signal generator having a signal generator input and a signal generator output, the signal generator configured to generate an output signal at signal generator output, the output signal oscillating at a non-zero frequency according to a control signal at the signal generator input;
an amplifier having an amplifier input and an amplifier output and an amplifier control input, the amplifier input coupled to the signal generator output, the amplifier output adapted to be coupled to an ultrasonic transducer, the transducer adapted to be mechanically coupled to a lens and configured to vibrate the lens according to an oscillating drive signal, and the amplifier configured to generate the oscillating drive signal at the amplifier output by amplifying the output signal;
a current sense circuit having a current sense input and a current sense output, the current sense input adapted to be coupled to the transducer, and the current sense circuit configured to sense a drive current flowing in the transducer and to generate a current sense signal at the current sense output, the current sense signal representing the drive current;
a control circuit having a control input and a control output, the control input coupled to the current sense output, the control output coupled to the signal generator input, and the control circuit configured to generate the control signal at the control output according to the current sense signal; and
a protection circuit having a protection circuit input and a protection circuit output, the protection circuit input coupled to the current sense output, the protection circuit output coupled to the amplifier control input, the protection circuit configured to generate a protection signal a

Assignees

• Texas Instruments Inc

Inventors

• Li Yunhong
• Khan Nabeel Fuad

Classifications

• H04N23/811

  by dust removal, e.g. from surfaces of the image sensor or processing of the image signal output by the electronic image sensor · CPC title

• B60S1/56

  specially adapted for cleaning other parts or devices than front windows or windscreens {(rear-view mirror arrangements mounted on vehicle exterior including cleaning devices B60R1/0602)} · CPC title

• B08B7/028

  Using ultrasounds · CPC title

• G02B27/0006 Primary

  with means to keep optical surfaces clean, e.g. by preventing or removing dirt, stains, contamination, condensation (G02B1/18 takes precedence; cleaning in general B08B) · CPC title

• H04N5/2171

  Electricity · mapped topic