Patent Description:
In this description, a lens structure includes a lens, lens cover, or other surface through which a signal (e.g., light) may pass, and where the apparatus is exposed to potential contaminants that may reduce the likelihood of successful signal passage through the apparatus. As one prominent example, in the automotive industry, cameras are assuming an important role in both Driver-Assisted Systems (DAS) and automatic safety systems. This technology commonly first appeared in relatively expensive vehicles and has migrated to less expensive ones. Indeed, the National Highway Traffic Safety Administration (NHTSA) has mandated that all new cars must be outfitted with rear view cameras by <NUM>. Cameras are also now being incorporated into side view mirrors to assist drivers with lane changes and currently under consideration by at least one automobile manufacturer is the possible replacement of vehicle side view mirrors with side view cameras. Besides alleviating blind spots for the driver, front cameras integrated into the windshield provide Forward Collision Warning (FCW), Following Distance Indication (FDI), and Lane Departure Warnings (LDW).

In the above-described context and others, and as the trend toward additional lens structure increases or becomes more ubiquitous, keeping the lens structure (e.g., lenses and lens covers) free of contaminants becomes a more prevalent need and is particularly important in safety-related applications. In a convention approach, several manufacturers have considered a miniature spray and wiper system. However, this design requires: (a) a small pump and nozzle; (b) a motorized wiper assembly; and (c) running a hose from a fluid tank to the location of the nozzle, which may necessitate a run from the vehicle front where a fluid tank is typically located, to the vehicle back, at least for the rear view camera, which is typically located at the rear of the vehicle. As a result, this design is mechanically complex and potentially expensive. <CIT> discloses a lens barrel, a camera, and a camera system. Further, <CIT> discloses a lens cleaning apparatus. Moreover, <CIT> discloses a vibrating device and image equipment having the same.

In described examples, a lens structure system comprises a lens structure and a multi-segmented transducer coupled to the lens structure. The multi-segmented transducer comprises a plurality of segments. For each of the segments, a respective first conductor and a respective second conductor are electrically coupled to the segment.

<FIG> illustrates various views of a lens structure cleaning system <NUM> according to a preferred embodiment. For example, <FIG> illustrates system <NUM> in a perspective exploded view, thereby separately illustrating a lens cover <NUM> that is to be coupled to of an ultrasonic transducer <NUM>, that is, affixed in some manner (e.g., atop an upper annular surface, directly, or indirectly through an additional member(s)) of an ultrasonic transducer <NUM> so that vibrations from ultrasonic transducer <NUM> may be transmitted either directly, or indirectly via any intermediate apparatus, to lens cover <NUM>. <FIG> illustrates a top view of just ultrasonic transducer <NUM>, and <FIG> illustrates lens cover <NUM> after being affixed atop the upper annular surface of an ultrasonic transducer <NUM>, as may be achieved via various adhesives that may be selected. Various aspects of system <NUM> are further described hereinbelow, with reference to all three of these drawings.

Lens cover <NUM> represents any type of conventional lens structure. In the example of system <NUM>, lens cover <NUM> is a disc with a transparent center section <NUM>SC (shown with a contrasting shading for distinction to the remainder) and an outer annular ring <NUM>AR that surrounds transparent center section <NUM>SC. Generally, light in the visible spectrum may readily pass through transparent center section <NUM>SC, while it is otherwise blocked by outer annular ring <NUM>AR. In this manner, and while not shown, a camera, and its respective lens, may be placed proximate lens cover <NUM>, so generally light may pass through transparent center section <NUM>SC so as to reach the camera lens, but the lens is otherwise protected by the additional surface provided by lens cover <NUM>. In many environments, transparent center section <NUM>SC may become occluded by the presence of additional contaminating matter (e.g., dirt, water, other airborne constituents) so that light is partially or fully blocked from passing through that section, and the preferred embodiments endeavor to reduce or dispel such matter from the surface of lens cover <NUM>.

Transducer <NUM>, in a preferred embodiment, is formed from a cross-section of a cylindrical piezoelectric material, and it preferably has an outer diameter smaller than the outer diameter of lens cover <NUM>. For example, the outer diameter of transducer <NUM> may be <NUM> to <NUM>, while the larger outer diameter of lens cover <NUM> may be <NUM> to <NUM>. Thus, after being assembled (e.g., <FIG>), the outer perimeter of lens cover <NUM> extends in some margin beyond the outer diameter of transducer <NUM>. As described hereinbelow, such a configuration may improve the effectiveness of standing waves transmitted from transducer <NUM> to lens cover <NUM>, thereby improving the ability to dispel contaminants from the surface of that lens cover. Transducer <NUM> is a segmented transducer, as defined by having plural circular sectors, each having a pair of conductors so as to apply a voltage to the sector. In the example illustrated, transducer <NUM> has four such segments (or sectors), shown in <FIG> as S<NUM>, S<NUM>, S<NUM>, and S<NUM>, each consisting of approximately <NUM> degrees of the entire <NUM> degree circular cross-sectional perimeter of the transducer. Each segment Sx has an outer electrode SOEx and an inner electrode SIEx, as may be achieved by silk-screening or otherwise attaching a thin conductive material to the respective outer and inner diameter of the piezoelectric material. As shown in a later <FIG>, electrical connectors/wires may be connected to each of the illustrated electrodes, thereby permitting signals to be applied, and alternated in amplitude, sign, and frequency, so as to achieve various preferred embodiment aspects further described hereinbelow.

In view of the preferred embodiment apparatus described hereinabove, transducer <NUM> may be excited with various signals so as to communicate vibrational forces into the abutted lens cover <NUM>. Such waves may be communicated in three different vibration modes, namely, radial mode at low frequencies (e.g., <NUM>) and which are along the radii of the circular cross section of transducer <NUM>, axial mode at relative middle frequencies (e.g., <NUM>), which are in the direction of the axis of the cylindrical transducer (i.e., vertical in <FIG>), , and a wall mode at higher frequencies (e.g., <NUM>), which are modes that represent the radial motion of the wall thickness with respect to the outer wall of transducer <NUM>. In a preferred embodiment, axial mode vibrations are preferred, as they are likely to cause vibrations that are tangential from the surface of lens cover <NUM>, thereby providing a greater likelihood of dislodging certain contaminants (e.g., dust, water) from that surface. Frequency ranges of the various mode types may overlap. For example, high order radial modal frequencies will overlap with the axial modal frequencies, and high order axial modal frequencies will overlap with wall modal frequencies. However, in practice, this is not normally an issue because as mode orders increase, so does the modal damping.

Further to the example hereinabove, also in the preferred embodiment, the vibrational forces are applied at excitation amplitudes and frequencies so as to transmit standing waves into the desirably chosen circular membrane shape of the abutted lens cover <NUM>. In certain areas of physics, a standing wave is a stationary vibrational pattern created within a medium when two waves of the same frequency propagate through the medium in opposite directions. As a result, regions of minimum displacement (e.g., nodes) and regions of maximum displacement (e.g., anti-nodes) are created at fixed locations in the medium. As a result, the waves cause displacement along the medium (i.e., lens cover <NUM> in this instance), yet at the physical locations where wave interference occurs, little or no movement occurs. Accordingly, in a circular membrane as exists in the preferred embodiment, where standing waves are so transmitted, certain mode shapes exist of the vibrational tendencies and movements of the surface being vibrated. Each mode shape is identified by a convention of mode (d,c) shape, where d is the number of nodal diameters across the membrane surface, and c is the number of nodal circles at or within the perimeter of the circular membrane, where the term nodal (or node) refers to a point, line, or circle on the structure that has zero amplitude vibration, that is, it does not move, while the rest of the structure is vibrating. Various examples of mode shapes are described hereinbelow.

To further introduce mode shapes and various preferred embodiment aspects, <FIG> and <FIG> illustrate perspective views, and <FIG> and <FIG> illustrate side views, of a membrane MEM and its mode shape diagrams of a first mode (<NUM>,<NUM>) shape that may be achieved by applying a voltage to the multiple-segmented transducer <NUM> of the preferred embodiment as if it were a single segmented transducer; such an effect may be achieved, therefore, by applying a first sine wave potential to all of its outer electrodes and a second sine wave potential, <NUM> degrees offset from the first sine wave (also achievable by a cosine counterpart to the sine), to all of its inner electrodes, where both sine waves have a same first modal frequency. Alternatively, the effect may be achieved by applying a sine wave potential to all of the outer electrodes while connecting the inner electrodes to ground (or, vice versa, that is, grounding the outer electrodes and connecting the same sine wave to all inner electrodes). A modal frequency is one of the resonant frequencies for the system under consideration (i.e., here, lens cover <NUM>), where the particular resonant frequency, among multiple resonant frequencies of the system, causes the shape of the respective mode. Therefore, <FIG>, <FIG> represent an instance where transducer <NUM> receives a voltage and first modal frequency, fm(<NUM>,<NUM>), which creates mode (<NUM>,<NUM>) shape, also known as a "cupping" mode, as further described hereinbelow.

The depictions of <FIG> and <FIG> are generally representative of a perspective circular shape as shown by concentric circles between a center point and the outer perimeter. Radial lines are also shown, and if the shape were flat such lines would be straight. However, a curved radial line suggests movement along the line. Therefore, <FIG> illustrates a first extreme of the oscillatory movement of member MEM, where the surface bends upward (e.g., for reference, in a positive direction) with a peak elevation at the center of the shape (also shown by light gray shading). The upward bend is also shown in the counterpart side view of <FIG>, which shows the mode surface as contrasted to a horizontal, or flat, reference line RL that is shown by a dashed line. In opposite fashion, <FIG> illustrates a second extreme of the oscillatory movement of member MEM, where the surface bends downward (e.g., for reference, in a negative direction) also with a peak elevation at the center of the shape (also shown by dark gray shading). The downward bend is also shown in the counterpart side view of <FIG>.

In view of <FIG>, <FIG>, the reference of a mode (<NUM>,<NUM>) indicates zero (i.e., d=<NUM>) nodal diameters and a single (i.e., c=<NUM>) nodal circle, the former shown as D<NUM>. The location of the nodal circle will depend on the conditions at the boundary of the membrane, where the illustrations assume that boundary is claimed; however, if the boundary were not claimed, the radial location of the nodal circle will change. Accordingly, as member MEM oscillates between the extreme positions shown in the drawings, a single circle, around the outside perimeter, does not vibrate. The vibrations inside nodal circle with diameter D<NUM>, therefore, will have some efficacy in removing contaminants that are on the surface of member MEM, but any matter that lands at (or near) the nodal circle with diameter D<NUM> may not experience sufficiently high acceleration to be removed. Further, material in high vibration zones may be pushed into these nodal circles. Also, a singular mode (<NUM>,<NUM>) has a limited area on membrane MEM that may reach a desirable amount of axial acceleration, thereby limiting the ability of the membrane to dispel contaminants.

Also, for example, <FIG> and <FIG> illustrate perspective views, and <FIG> and <FIG> illustrate side views, of a membrane MEM and its mode shape diagrams of a second mode (<NUM>,<NUM>) shape that may be achieved by applying a voltage to the multiple-segmented transducer <NUM> of the preferred embodiment again as if it were a single segmented transducer, by again applying respective <NUM> degree out-of-phase sine waves to all of its outer electrodes and to all of its inner electrodes, but here at a second modal frequency, fm(<NUM>,<NUM>), which creates mode (<NUM>,<NUM>) shape, as further described hereinbelow.

The depictions of <FIG> and <FIG> are again representative of a perspective circular shape as shown by concentric circles and radial lines, where <FIG> illustrates a first extreme of the oscillation, and <FIG> illustrates a second and opposite extreme of the oscillation. In the first extreme shown in <FIG>, and in the counterpart horizontal plot of <FIG>, membrane MEM has a peak positive amplitude extending upward at the center of the shape, while at the same time membrane MEM also extends downward below the reference line RL, beyond the radii that is larger than a nodal circle with diameter D<NUM>. In opposite fashion, in the second extreme shown in <FIG>, membrane MEM has a peak negative amplitude extending downward at the center of the shape, while at the same time membrane MEM also extends upward above the reference line RL, beyond the radii that is larger than the nodal circle with diameter D<NUM>. Thus, as indicated by the (<NUM>,<NUM>) reference, the mode shape of these drawings has (i.e., d=<NUM>) nodal diameters and two (i.e., c=<NUM>) nodal circles, one nodal circle at the outer perimeter shown with diameter D<NUM>, and the other nodal circle as described hereinabove with diameter D<NUM>, where the surface of membrane MEM having a diameter less than D<NUM> bend in a first direction, while the surface of membrane MEM having a diameter greater than D<NUM> bend in a second direction, opposite the first direction. Such an approach also will have some efficacy in removing contaminants that are on the surface of member MEM, but contaminants may tend to remain at both nodal circles with diameters D<NUM> and D<NUM> and a singular application of the mode (<NUM>,<NUM>) shape will have limited acceleration across much of the area of membrane MEM.

Accordingly, certain modes achievable by transducer <NUM>, if operated by applying voltages to multiple segments at the same time so as to function as a single segmented transducer, result in axle symmetric mode shapes. For example, the (<NUM>,<NUM>) shape has a single outer nodal circle with diameter D<NUM> at its perimeter, and inside that perimeter the flexing is circularly symmetric as shown by the comparable concentric circles with radii inside that outer nodal circle. As another example, the (<NUM>,<NUM>) shape also has an outer nodal circle at its perimeter, within which the flexing of the membrane is again along equally flexing radii, but where the flexing can be in opposite directions, relative to an inner concentric nodal circle with diameter D<NUM>. However, such symmetry in the flexing may be less likely to expel certain contaminants from lens cover <NUM>, or it may tend to accumulate contaminants in nodal points or circles. The preferred embodiments include additional modes of operation, therefore, so as to achieve improved results over these considerations, as further described hereinbelow.

<FIG> again illustrates transducer <NUM> in the same general manner as depicted in <FIG>, although in <FIG> the illustration is rotated for sake of reference, and conductors are shown connected to pairs of respective segment outer electrodes SOEx and inner electrodes SIEx. Moreover, a potential is defined between each paired set of conductors. For example, the voltage between outer electrode SOE<NUM> and inner electrode SIE<NUM> is defined as vS1. Also, the (+) and (-) conventions define a polarity for sake of reference, but (as described hereinbelow) not to suggest that the outer electrode is always positive with respect to its inner counterpart. Therefore, to further illustrate this convention, a voltage of +1V applied to vS1 suggests that the one volt is positive to outer electrode SOE<NUM> relative to inner electrode SIE<NUM>, while a voltage of -1V applied to vS1 suggests that the one volt is negative to outer electrode SOE<NUM> relative to inner electrode SIE<NUM>.

In view of the description hereinabove, while all sets of conductors of transducer <NUM> may receive a voltage at a single time, such as described hereinabove, a conductor subset also may receive a voltage in a preferred embodiment. For example, a sine wave at a modal resonant frequency fm(<NUM>,<NUM>) may be applied to one pair of conductors/electrodes, with a <NUM> degree opposite phase sine wave at the same resonant frequency fm(<NUM>,<NUM>) applied to an opposing pair of conductors/electrodes. Thus, in a preferred embodiment, a first phase of the sine wave is applied to vS1, while a second phase of the sine wave, <NUM> degrees apart from the first phase, is applied to vS3; at the same time, no voltage is applied to vS2 or vS4. With this voltage application, a mode (<NUM>,<NUM>) shape is achieved, as shown in a first oscillatory cycle in perspective and horizontal views in <FIG>, and in a second oscillatory cycle in perspective and horizontal views in <FIG>. As shown in those drawings, in mode (<NUM>,<NUM>) shape, membrane MEM again has a nodal circle around its outer perimeter. Also, however, one diameter line DL<NUM> represents a nodal line, as oscillations occur left and right of that line, due to the voltage applied to of opposing pairs of conductors/electrodes as described hereinabove (e.g., to vS1 and vS3). Thus, to further illustrate additional aspects hereinbelow, the alternative oscillations about diameter line DL<NUM> also may be represented in a top view, as shown in <FIG>, which generally illustrates the two separate oscillating regions OR<NUM> and OR<NUM>, about line DL<NUM>.

The mode (<NUM>,<NUM>) shape described hereinabove does not include symmetric nodal circles of the mode (<NUM>,<NUM>) described hereinabove, so advantages are achieved by implementing the mode (<NUM>,<NUM>) shape with vibrating lens cover <NUM> via transducer <NUM>, because such implementation does not have an inner ring as represented by the inner nodal circle with diameter D<NUM> described hereinabove. Accordingly, expelling contaminants may be achieved in a fashion that is more likely to avoid circular residue. However, in a further aspect of the preferred embodiment, at an alternative time, the same sine wave/off phase voltage at a frequency fm(<NUM>,<NUM>) is applied to conductor/electrode pairs with signals vS2 and vS4, while at the same time no voltage is applied to vS1 or vS3, instead of only applying voltage to conductor/electrode pairs with signals vS1 and vS3 at a frequency fm(<NUM>,<NUM>) and with a sine wave <NUM> degrees out of phase with respect to the two signals. Such an approach yields the result illustrated in <FIG>, where again a mode (<NUM>,<NUM>) shape is achieved with the two separate oscillating regions OR<NUM> and OR<NUM>, about a single nodal line DL<NUM>, but the nodal line and oscillating regions are rotated <NUM> degrees relative to <FIG>. Therefore, the vibration and acceleration forces imposed on lens cover <NUM> in <FIG> (at regions OR<NUM> and OR<NUM>) are in different locations (i.e., <NUM> degrees offset) than at regions OR<NUM> and OR<NUM> in <FIG>. Accordingly, in a preferred embodiment, a switching driver architecture is implemented to switch between these two (or other) alternatives, so as to achieve the advantages of more than one vibrational mode, as described hereinbelow.

<FIG> illustrates a preferred embodiment method <NUM> of operating system <NUM>. For example, method <NUM> may be controlled by a processor, controller or other circuit or device, as may be hardwired or programmed by suitable techniques. Also, for example, such control advances method <NUM> so as to apply transducer voltages to selective ones (or all) of the conductors/electrodes of system <NUM>, so as to alternate between different mode shapes created in lens cover <NUM>, via standing waves applied to it from transducer <NUM>. In combination, therefore, the standing waves increase the ability to accelerate the surface of lens cover <NUM> so as to achieve a desirably sufficient amount of acceleration coverage across a majority of the area of the cover. As a result, the accelerated movement of the lens cover increases the chances of dispelling portions of any contaminants along a majority of the area of the cover. Additional details follow.

Method <NUM> commences with a start step <NUM>, which may be initiated by various apparatus or events, when desired to start an attempt to remove particulate from lens cover <NUM> by vibrating it via transducer <NUM>. For example, where lens cover <NUM> is part of an automotive application as described hereinabove and further described hereinbelow, start step <NUM> may be user actuated, such as by an operator of the automobile, or a processor can initiate the step in response to a condition, such as at system start-up, or after the passage of time, or response from a sensor or upon detection of some other event, such as rain, that might cause some matter (e.g., water) to come in contact with the exterior of lens cover <NUM>. In any event, after step <NUM> is enabled, method <NUM> has begun, after which method <NUM> continues from step <NUM> to step <NUM>.

In step <NUM>, a mode counter md is initialized to a value of one. As described hereinbelow, mode counter md increments, and thereby provides a count, up to a total number of modes TLM that are shaped onto lens cover <NUM>, by transducer <NUM>, in cyclic and alternating fashion, so as to attempt to remove contaminants from lens cover <NUM>. Next, method <NUM> continues from step <NUM> to step <NUM>.

In step <NUM>, voltage is applied to a set of selective ones or all of the electrodes of transducer <NUM>, via the respective conductors connected to those electrodes, so as to achieve a mode, indicated as MODE[md], meaning according to the index provided by counter md. Thus, for a first occurrence of step <NUM>, then a first mode (i.e., MODE[<NUM>]) is effected by applying the necessary voltage signals to a first set of electrodes so as to accomplish that mode. In at least one example, the first mode is the application of the mode (<NUM>,<NUM>) shape, described hereinabove in connection with <FIG>, <FIG>, <FIG> and <FIG>. To achieve this mode, all outer electrodes SOEx receive a voltage of a first sine wave, while all inner electrodes SIEx receive a voltage of a second sine wave of the same sample amplitude as the first sine wave, but with the two waves phase offset by <NUM> degrees; moreover, both sine waves are applied with a frequency fm(<NUM>,<NUM>), which is the resonant frequency of system <NUM> required to achieve the mode (<NUM>,<NUM>) shape. Lastly, step <NUM> applies the signals to the selected set of conductor/electrodes for a number indicated as MC cycles, that is, for a duration of input sign waves equal to MC periods or cycles. The value of MC may be selected by various considerations. For example, MC may be based on a pre-programmed value or on a feedback signal (e.g., modal resonance frequency which will return to a baseline value as contaminant mass is ejected from the surface), or from information from a camera system (from which a determination is possible about whether a sufficiently clear image is obtained through the lens). After the MC cycles at the current MODE[md] have been achieved, method <NUM> continues from step <NUM> to step <NUM>.

In step <NUM>, a condition is evaluated to determine whether the mode counter md has reached a total number of modes TLM that are desired to be shaped onto lens cover <NUM>, by transducer <NUM>. If md is less than TLM, then method <NUM> advances from step <NUM> to step <NUM>, whereas if md equals TLM, then method <NUM> advances from step <NUM> to step <NUM>. In step <NUM>, the mode counter md is incremented and the flow returns to step <NUM>. In a repeat of step <NUM>, therefore, an additional set of selective ones or all of the electrodes of transducer <NUM> receive a voltage so as to achieve a next mode, indicated as MODE[md], which in the case of a first repetition of step <NUM> will be the second mode, that is, MODE[<NUM>]. In at least one example, the second mode is the application of the mode (<NUM>,<NUM>) shape, described hereinabove in connection with <FIG> and <FIG>. To achieve this mode, a first phase of the sine wave is applied to vS1, while a second phase, <NUM> degrees apart from the first phase, of the sine wave is applied to vS3, while at the same time no voltage is applied to vS2 or vS4, and both sine waves are applied with a frequency fm(<NUM>,<NUM>). Again, step <NUM> applies these signals to the selected set of conductor/electrodes for MC cycles, after which method <NUM> again continues from step <NUM> to step <NUM>.

Step <NUM> is described hereinabove, as it evaluates the condition of whether the mode counter md has reached a total number of modes TLM that are desired to be shaped onto lens cover <NUM>, by transducer <NUM>. In view of the sequencing described herein, and the potential looping from step <NUM> not being satisfied and returning to step <NUM> one or more times for the application of respective additional modes, TLM may be set to any number with a corresponding indication of each MODE[md] to be applied for each incidence of step <NUM>. Continuing with this example, after a first occurrence of step <NUM> applies the mode (<NUM>,<NUM>) shape and a second occurrence of step <NUM> applies the mode (<NUM>,<NUM>) shape per <FIG> (i.e., applying vS1 and the <NUM> degree apart vS3,), with TLM set to three a third occurrence of step <NUM> may be reached to apply the mode (<NUM>,<NUM>) shape per <FIG> (i.e., applying vS2 and the <NUM> degree apart vS4). In this case, after the third occurrence, the condition of step <NUM> is satisfied and method <NUM> continues to step <NUM>.

In step <NUM>, a condition is evaluated to determine whether a sufficient duration of cycles has been applied by the preceding occurrence(s) of step <NUM>. In relation to this step, each incidence of step <NUM> excites transducer <NUM> to apply a standing wave mode shape to lens cover <NUM>, for a total of MC cycles per step <NUM> incidence. Each of these MC cycles, therefore, endeavors to clear contaminants from the surface of lens cover <NUM>. Depending on the number of cycles per step <NUM> incidence, and the number of step <NUM> occurrences, repeating the occurrence(s) of step <NUM> may be desirable for all TLM modes MODE[md] one or more additional times, in an ongoing effort to clear contaminants from the surface of lens cover <NUM>. Thus, the step <NUM> condition may use duration (or some other measure) as a basis to evaluate whether to repeat the occurrence(s) of step <NUM> for all modes MODE[md]. If such a repetition is desired, method <NUM> returns from step <NUM> to step <NUM>, whereas if step <NUM> is satisfied, then method <NUM> ends in step <NUM>. While method <NUM>, therefore, concludes with step <NUM>, it may be subsequently re-started by returning to step <NUM>, by one of the actions as described hereinabove with respect to that step.

In view of the description hereinabove, with TLM=<NUM> and the modes described, that method <NUM> applies a sequence of three different modes, each for MC cycles, so as to vibrate lens cover <NUM> in differing fashions. Further, acceleration from modal vibration may be represented by the following Equation <NUM>: <MAT> where: a(d,c) is acceleration for a mode (d,c); ω(d,c) is resonance frequency for a mode (d,c); and z(d,c)(r,θ) is the mode shape for mode (d,c) which is a function of the radius r from the center and the angle θ about the circumference with respect to a reference angle (i.e., vertical displacement in a polar coordinate system).

From Equation <NUM>, therefore, acceleration is a function, in part, of the frequency squared. Moreover, in each of the multiple different modes, one area of lens cover <NUM> will achieve a maximum or peak acceleration, while various other areas of the lens cover will achieve some lesser percentage of that peak. In an effort to achieve the greatest likelihood of dispelling contaminants, therefore, a greater percentage of peak acceleration across a greater area of lens cover <NUM> is likely to be desirable. <FIG> illustrates a coverage map of lens cover <NUM> where a region RN<NUM> represents the area where acceleration of the lens cover surface reaches at least <NUM>% of its peak value. Region RN<NUM> corresponds to the example described hereinabove, where TLM=<NUM> and the three separate mode shapes applied (by respective incidences of step <NUM>) are mode (<NUM>,<NUM>), followed by mode (<NUM>,<NUM>) relative to a first nodal line (e.g., <FIG>), followed by mode (<NUM>,<NUM>) relative to a second nodal line (e.g., <FIG>), where the second nodal line is orthogonal to the first nodal line. Visually, therefore, <FIG> represents a considerable amount of coverage area where acceleration of at least <NUM>% of peak may be sufficient to dislodge or expel surface contaminants. Indeed, in connection with this preferred embodiment, <NUM>% of the entire area of the lens cover <NUM> is expected to reach at least <NUM>% of peak acceleration. Further, alternative results may be achieved by altering the number of and/or types of modes applied. Indeed, as more modes are included in an application of method <NUM>, and for a given acceleration threshold (e.g., <NUM>% of acceleration peak for the above-described example), as more modes are added, the area coverage monotonically increases. Therefore, transducer <NUM> may receive voltage to achieve a mode (<NUM>,<NUM>) shape, which <FIG> illustrates in a top view representation. The mode (<NUM>,<NUM>) shape has two nodal lines DL<NUM> and DL<NUM> and a single outer perimeter nodal circle. With the two nodal lines DL<NUM> and DL<NUM>, four separate oscillating regions OR<NUM>, OR<NUM>, OR<NUM> and OR<NUM>, occur, and these regions therefore may be added to the regions covered by the above-described modes, such as by increasing TLM to four and adding the <FIG> mode as yet another mode in method <NUM>. Accordingly, <FIG> illustrates a coverage map of lens cover <NUM> with a region RN<NUM>, again representing the area where acceleration of the lens cover surface reaches at least <NUM>% of its peak value, where mode (<NUM>,<NUM>) has been added as a fourth step <NUM> vibrational pattern, over and above the example described hereinabove and illustrated by acceleration area coverage in <FIG>. By comparing FIG. <NUM> to FIG. <NUM>, a confirmation may be obtained that the areal coverage is increased with additional mode (<NUM>,<NUM>). Also, the central area (where peak acceleration is not achieved as shown in <FIG>) is considerably reduced in <FIG>.

In view of the description hereinabove, the preferred embodiment provides numerous alternative sequences of mode shapes to accomplish varying acceleration areal coverage across lens cover <NUM>. For example, the following Table <NUM> lists empirical numbers are an estimation of what may be achieved in one apparatus, where the maximum amplitude across all mode shapes is equal.

Table <NUM> lists a percentage of the entire area of member MEM that experiences an acceleration that reaches or exceeds a percentage of peak acceleration. For example, according to the first row of Table <NUM>, a peak acceleration occurs somewhere across lens cover <NUM> (i.e., member MEM) in response to the mode or modes applied to it by transducer <NUM>, and if the preferred embodiment applies only the mode (<NUM>,<NUM>) shape as shown in the table second column (e.g., by a singular incident of step <NUM> in method <NUM>), then <NUM>% of the area of lens cover <NUM> is accelerated to at least <NUM>% of that peak. However, as shown in the third column of the first row of Table <NUM>, the areal coverage is increased considerably by adding two additional step <NUM> incidences, each to apply a respective one of the two orthogonal mode (<NUM>,<NUM>) shapes (see <FIG>); in this case, then more than a majority of the area, namely, <NUM>% of the area of lens cover <NUM> is accelerated to at least <NUM>% of that peak.

Still further, as shown in the fourth column of the first row of Table <NUM>, the areal coverage is increased still further by adding an additional step <NUM> incidence to apply the mode (<NUM>,<NUM>) shape in addition to the (<NUM>,<NUM>) and two orthogonal mode (<NUM>,<NUM>) shapes, where <NUM>% of the area of lens cover <NUM> is accelerated to at least <NUM>% of that peak. The remaining examples of Table <NUM> should be readily understood. In each instance of the third and fourth columns, more than one-half of the area of the lens cover <NUM> reaches or exceeds the indicated peak threshold. Moreover, other combinations and numbers of mode shapes may be readily implemented per the preferred embodiments.

<FIG> illustrates an electrical block diagram of a driver architecture <NUM> that may be used to drive the conductors of a segmented transducer <NUM> according to a preferred embodiment. Architecture <NUM> includes an oscillating wave (e.g., sine wave) source <NUM>, connected between a reference (e.g., ground) and an input to a single amplifier <NUM>. The output of amplifier <NUM> is connected to a number NS of crossbar switches CS<NUM> through CSNS. Each crossbar switch CSx has an input INx connected to the oscillating output of amplifier <NUM> and an inverted input INVx connected to ground. Moreover, each crossbar switch CSx has a first output SIEx for connecting to a respective inner electrode as described hereinabove in connection with <FIG>, and a second output SOEx for connecting to an outer respective electrode as described hereinabove in connection with <FIG>.

In operation, each crossbar switch CSx is operable, in response to a respective control signal CLx, to either: (a) pass its oscillating signal input INx to its SIEx output, while connecting ground from its inverted input INVx to its SOEx output; or (b) cross-couple the ground signal from its inverted input INVx to its SIEx output, while connecting its input INx directly to its SOEx output; or (c) present a high impedance state where its inputs INx and INVx are not passed to either output. For example, therefore, to excite the mode (<NUM>,<NUM>) shape with a four segment transducer, four crossbar switches would be required with the following Table <NUM> listing the appropriate control inputs to realize that mode shape:.

In Table <NUM>, a control input of "P" indicates a direct pass through, while a control input of "X" indicates the crossbar operation, so the inputs are switched. Thus, Table <NUM> provides a same phase sine wave to opposing segments to segments Si and S<NUM>, while ground is applied to segments S<NUM> and S<NUM>, thereby transmitting standing waves so as to achieve the mode (<NUM>,<NUM>) shape. Other examples exist.

<FIG> illustrates a preferred embodiment vehicle V with system <NUM> implemented in numerous locations relative to the vehicle V. For example, a forward facing camera may be installed as part of a system <NUM> in a mount located behind the windshield W of vehicle V. As another example, a respective rearward facing camera may be installed as part of a system <NUM> in each of the vehicle side mirror locations SMR, either in addition to or in lieu of an actual side mirror. As a final example, another rearward facing camera may be installed near or at the rear of the vehicle V, so as to assist with backup technology. Each system <NUM> communicates with a processor P, such as a controller, microcontroller, or the like, located either under the hood or inside the interior of the vehicle, where such communication as may be connected by some type of conductors, including a vehicle network system. In any event, each system <NUM> is operable to capture light signals as images, for various types of processing and/or display. Moreover, as described hereinabove, each such camera has a lens structure (e.g., lens, lens cover), and associated therewith is a transducer that is operable according to method <NUM> so as to reduce any contaminants on the surface of the lens structure.

Accordingly, the preferred embodiments are shown to provide an ultrasound lens structure cleaner and architecture method, either as a standalone unit or as part of a larger preferred embodiment system (e.g., a vehicle). Such preferred embodiments provide numerous benefits. For example, greater vibration coverage of the lens structure surface is achieved with high transverse amplitudes. As another example, greater acceleration coverage is achieved of the lens structure surface. As yet another example, strains may be developed in multiple directions, rather than just the axial direction, to promote cracking of dried materials. More particularly, besides high transverse acceleration (orthogonal to the surface), lateral strain can be developed, which may be important for cracking dried contaminants. Thus, strain may be imposed on the lens surface in both the radial and tangential directions. Thus, whereas due to the circular nature of the mode shape, strain is only applied in the radial but not in the tangential direction, the preferred embodiment may apply strain additionally in the tangential direction, so contaminants can be even more effectively removed. Specifically, asymmetric modes (e.g., mode (<NUM>,<NUM>) shape) will apply strain in both directions, leading to more effective cracking. As still another benefit, a straightforward driver circuit may drive system <NUM>, requiring only a single amplifier. Still further, the preferred embodiments are implemented without vibration or resonance frequency matching issues.

Claim 1:
A lens structure system (<NUM>), comprising:
a lens structure;
a single amplifier (<NUM>) including an input and an output;
an oscillating wave source (<NUM>) connected between a reference and the input of the single amplifier (<NUM>);
a multi-segmented transducer (<NUM>) coupled to the lens structure, comprising a plurality of segments (Sx); and
per segment in the plurality of segments (Sx):
a respective first conductor (SIE) and a respective second conductor (SOE) electrically coupled to the segment; and
a respective crossbar switch (CSx) coupled: between the oscillating wave source (<NUM>) via the output of the single amplifier (<NUM>) and the respective first conductor (SIE); between the oscillating wave source (<NUM>) and the respective second conductor (SOE); between a ground and the respective first conductor (SIE); and between the ground and the respective second conductor (SOE); and
the respective crossbar switch (CSx) having a respective control signal input (CLx).