KR102180166B1 - Method of forming a transducer controller and circuit therefor - Google Patents

Abstract

In one embodiment, the transducer controller is configured to form a drive signal having a first frequency for driving the transducer. The drive signal has a period and a half period and drives the transducer during the first part of the half period. The transducer controller detects the voltage formed by the transducer during the second part of the half period, measures the parts of the voltage, estimates the phase error between the first frequency and the resonant frequency of the transducer, and calculates the first frequency. Configured to adjust to a second frequency that reduces the phase error.

Description

Transducer controller and method of forming a circuit therefor

preceding In a provisional application Claiming priority

This application is filed on October 21, 2015 by co-inventors, Kutej et al., whose case number is ONS02087, and the name of the invention is "Method OF FORMING A TRANSDUCER. CONTROLLER AND CIRCUIT THEREFOR)", prior filed Provisional Application No. 62/244,391, which is hereby incorporated by reference.

TECHNICAL FIELD The present invention relates generally to electronic devices, and more particularly to semiconductors, structures thereof, and methods of forming semiconductor devices.

In the past, the electronics industry has used various methods and circuits to form controllers for ultrasonic transducers. In some applications, the ultrasonic transducer may have been used as part of a distance measurement system. The distance measurement system can be used in vehicles to detect distances, such as providing distance measurement for parking assistance applications. Some of the ultrasonic transducers may have a narrow frequency band that can be used for transmission of acoustic signals and reception of reflected acoustic signals. Such a frequency may be referred to as the resonant frequency of the transducer or the transducer resonant frequency. Typically, the transducer resonant frequency may have been affected by various environmental conditions. For example, the transducer resonance frequency may have been dependent on the ambient temperature. In addition, rainwater or ice may form on the transducer, and may have also affected the transducer resonance frequency.

Therefore, it may be advantageous to have a transducer controller capable of adjusting changes in the resonant frequency of the transducer 12.

1 schematically illustrates an example of an embodiment of a portion of an acoustic measurement system with a piezo-electric transducer according to the present invention.
FIG. 2 schematically illustrates an example of an embodiment of a simplified equivalent circuit model of the transducer of FIG. 1 according to the present invention.
3 is a graph illustrating an example embodiment of some signals formed as a result of the operation of the controller of FIG. 1 in accordance with the present invention.
4 is a diagram comprising graphs illustrating non-limiting examples of some embodiments of the signals formed during operation of one embodiment of the controller of FIG. 1 in accordance with the present invention.
5 is a graph illustrating non-limiting examples of some embodiments of the signals formed during operation of one embodiment of the controller of FIG. 1 in accordance with the present invention.
6 is a graph illustrating a non-limiting example of an embodiment of an enlarged view of portions of the graph of FIG. 5 in accordance with the present invention.
7 is a graph illustrating another non-limiting example of an embodiment of an enlarged view of portions of the graph of FIG. 5 in accordance with the present invention.
8 is a graph illustrating a non-limiting example of one embodiment of the dependence between a phase error and a calculated ratio R according to the present invention.
9 schematically illustrates a portion of an example of an embodiment of a circuit that may be part of the circuit of FIG. 1 in accordance with the present invention.
10 is a graph illustrating some signals that may be formed by an embodiment of the controller of FIG. 1 in accordance with the present invention.
11 schematically illustrates an example of an embodiment of a portion of a transducer controller, which may be an alternative embodiment of at least a portion of the controller of FIG. 1 in accordance with the present invention.
12 is a graph illustrating a non-limiting example of one embodiment of some signals resulting from operation of the controller of FIG. 11 in accordance with the present invention.
13 is a graph illustrating a non-limiting example of one embodiment of some signals resulting from operation of the controller of FIG. 11 in accordance with the present invention.
14 schematically illustrates an example of a portion of an embodiment of a driving circuit, which may be an alternative embodiment of a portion of the controller of FIG. 1 or 11 according to the present invention.
15 schematically illustrates an example of a portion of an embodiment of a three terminal transducer according to the present invention.
16 is a graph illustrating a non-limiting example of an embodiment of some of the signals during an embodiment of a drive period according to the present invention.
17 is a diagram illustrating an enlarged plan view of a semiconductor device including an embodiment of the controller of FIG. 1 or 11 in accordance with the present invention.
For simplicity and clarity of the illustration(s), elements in the drawings are not necessarily drawn to scale, some of the elements may be exaggerated for purposes of illustration, and the same reference numerals in different drawings are not mentioned otherwise. Unless they represent the same elements. In addition, descriptions and details of well-known steps and elements may be omitted for simplicity of description. As used herein, a current carrying element or current carrying electrode is a source or drain of a MOS transistor, or an emitter or collector of a bipolar transistor, or of a diode. It refers to an element of a device that carries current through the device, such as a cathode or an anode, and the control element or control electrode is the gate of a MOS transistor or the base of a bipolar transistor, It refers to the element of the device that controls the current through the device. Moreover, one current-carrying element can carry current in one direction through the device, such as carrying current entering the device, and the second current-carrying element is opposite through the device, such as carrying current out of the device. It can carry current in any direction. While devices may be described herein as certain N-channel or P-channel devices, or certain N- or P-type doped regions, those skilled in the art will recognize that complementary devices are also possible in accordance with the present invention. something to do. One of skill in the art understands that the conduction type refers to the mechanism by which conduction occurs, such as through conduction of holes or electrons, and thus the conduction type refers to a doping type such as P-type or N-type rather than a doping concentration. Those of ordinary skill in the art are aware that the expressions during, during, and when, as used herein with respect to circuit operation, are not precise terms that mean that the operation occurs immediately upon the initiating operation, but between reactions initiated by the initial operation, various propagation delays. It will be appreciated that there may be some small but moderate delay(s), such as. Moreover, the term during means that a certain operation occurs within at least a portion of the duration of the initiating operation. The use of the expression approximately or substantially means that the value of the element has a parameter that is expected to be close to the stated value or position. However, as is well known in the art, there are always minor fluctuations that prevent values or locations from being exactly as stated. In the art, fluctuations up to at least 10 percent (10%) (and for some elements including semiconductor doping concentrations up to 20 percent (20%)) are appropriate fluctuations from the ideal target of what is exactly as described. It is well established. When used in relation to the state of a signal, the term "asserted" refers to the active state of the signal, and the term "negated" refers to the inactive state of the signal. The actual voltage value or logic state (such as "1" or "0") of the signal depends on whether positive or negative logic is used. Thus, the assertion can be high voltage or high logic or low voltage or low logic depending on whether positive or negative logic is used, and negative is a low voltage or low state depending on whether positive or negative logic is used. Alternatively, it may be high voltage or high logic. In this specification, a positive logic protocol is used, but those skilled in the art understand that a negative logic protocol may also be used. In the claims or/and in the detailed description of the drawings, terms such as first, second, third, etc. as used in part of the name of an element are used to distinguish between similar elements, and necessarily temporally, spatially, It is not used in rankings or to describe the order in any other way. It should be understood that the terms so used are interchangeable in appropriate circumstances and that the embodiments described herein are operable in different orders than those described or illustrated herein. Reference to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment, but may in some cases. Moreover, certain features, structures or properties may be combined in any suitable manner in one or more embodiments, as will be apparent to those of skill in the art. For clarity of the figures, the doped regions of the device structures are illustrated as having generally straight edges and precisely angled corners. However, those skilled in the art understand that due to diffusion and activation of dopants, the edges of the doped regions may not generally be straight lines, and the corners may not be at correct angles.
In addition, the description exemplifies a cell-type design (in which the body regions are a plurality of cellular regions) instead of a single body design (the body region consists of a single region formed in a long pattern, typically a serpentine pattern). do. However, the description is intended to be applicable to both a cell type implementation and a single base implementation.
The embodiments illustrated and described as suitable below may have embodiments and/or may be practiced without any elements not specifically disclosed herein.

1 schematically illustrates an example of an embodiment of a piezoelectric transducer Pz or a portion of an acoustic measurement system 10 having an acoustic transducer or transducer 12. An embodiment of the transducer 12 may have a signal terminal 17 and a second terminal 18. In one embodiment of the transducer 12, the terminal 17 may be configured to receive a drive signal to excite the transducer 12 to vibrate, and also exhibit reflection or reverberation. It can be configured to form a signal. In some embodiments, terminal 18 may be connected to a common reference voltage, or alternatively may be connected to a receiver to aid in the formation of signals from transducer 12. System 10 is illustrated using a two terminal transducer. As will be further seen below, other types of transducers may also be used, such as for example a three terminal transducer. In addition, system 10 is sometimes referred to as a transformer-less system, since the transformer is not used to couple the transducer 12 to the controller or to the driver circuit.

2 schematically illustrates an example of an embodiment of a simplified equivalent circuit model of the transducer 12. In some applications, the transducer 12 can be modeled as a series resonant network with a capacitor 15 connected in series with an inductor 14 and in series with a resistor 13, All are connected in parallel with a parasitic capacitor (Cp) 16.

Returning to FIG. 1, the system 10 also includes a drive signal 45 having a frequency and/or phase that is formed in response to the resonant frequency of the transducer 12 including changes in the resonant frequency of the transducer 12. And a transducer controller 20 that can be configured to form a. As used herein, the phrase "resonant frequency" refers to the resonant frequency of the transducer 12 including changes in the resonant frequency of the transducer 12.

The controller 20 is configured to receive power to operate the controller 20 between the voltage input 21 and the common return 22. In some embodiments, return 22 may be connected to a common voltage, such as a ground reference voltage, for example, or may be connected to a different voltage. System 10 may have an embodiment in which terminal 18 of transducer 12 may be connected to return 22. The controller 20 has input/output terminals 23 and 24 that may be configured to receive signals from the transducer 12 in one embodiment. Receiver circuitry or RX or RX circuit 28 of controller 20 may be configured to receive signals from transducer 12. Terminals 23, 24 or alternatively one embodiment of terminal 23 may also be configured to provide a drive signal to transducer 12. The Tx driver circuit or Tx or Tx circuit or driving circuit 41 of the controller 20 may be configured to form a driving signal 45 for driving or exciting the transducer 12. In some embodiments, terminal 24 may be omitted. The control circuit 32 of the controller 20 receives signals from the circuit 28, for example signal 33, and provides signals such as signals 36-37 to provide the signal 45 And/or may be configured to control part of the operation of the circuit 41. In some embodiments, circuit 32 may be formed to include a non-transitory computer readable medium such as a read-only memory or other structure capable of storing a program for forming a method described further below. have.

One embodiment of the controller 20 may be configured to control the transducer 12 to form a measurement cycle for measuring distance. The controller 20 forms a measurement cycle to include a subsequent ranging phase, which may include receiving a signal indicative of an echo or a reflected acoustic signal that may be used to measure the drive phase or transmit phase and distance. It can have an embodiment that can be configured to. The reverb is the reverberation received from the transmitted acoustic signal formed by the transmit phase. In some embodiments, the controller 20 may also include forming a measurement cycle to include an active damping phase after the transmit phase and before the ranging phase.

The transmit phase may include driving the transducer 12 with a drive signal 45 having one or more cycles to excite the transducer 12 to form a transmitted acoustic signal used to measure distance. . The value of the drive signal 45 may change during the cycle. The cycle of the drive signal 45 may include a first cycle or a drive cycle for forming the transmitted acoustic signal. As can be seen further below, an embodiment of the controller 20 determines that a difference exists between the resonance frequency and the frequency of the signal 45, and changes the frequency of the signal 45 in response to the difference. Can be configured to The presence of a difference between the resonant frequency and the frequency of the signal 45 is referred to herein as a “frequency difference”. Also, as used herein, the frequency of the signal 45 used to transmit an acoustic signal for measuring distance, including any changes to that frequency, is referred to as the “drive frequency”. Determining the frequency difference and adjusting the drive frequency to be substantially equal to the resonant frequency facilitates configuring the controller 20 to improve the sensitivity and accuracy of the measurement, and in some embodiments, the distance at which objects can be detected. Can increase

3 is a graph illustrating an example embodiment of some signals formed as a result of the controller 20 driving the transducer 12 as part of the transmit phase used to measure the distance. The plots of FIG. 3 illustrate a non-limiting exemplary embodiment of some conditions of an example of an embodiment of a method of controlling the transducer 12, such a method may be performed by the controller 20. . Plot 51 illustrates the states of switch 46 and plot 52 illustrates the states of switch 47. Plot 53 illustrates the voltage 25 formed across the transducer 12. Plot 54 illustrates the circulating current flowing within transducer 12. This description refers to FIGS. 1 and 3.

In one exemplary embodiment of the method of controlling the transducer 12, the controller 20 has a drive signal 45 to have a drive frequency and a corresponding drive period 55 labeled as “Tx period” in FIG. 3. It can be configured to form. The drive period 55 includes two half-periods 49 and 50 labeled as "½ Tx period". In one embodiment, the controller 20 applies a signal 45 having one polarity during one half cycle of the drive period 55, and a signal having the opposite polarity during successive half cycles of the drive cycle 55. It can be configured to apply 45. One embodiment of the controller 20 controls the transducer 12 comprising forming a signal 45 for driving the transducer 12 such that the transmit phase generates a transmitted sound wave for measuring distance. It can be configured to form a method. The signal 45 can induce a circulating current in the transducer 12 that can form a reverberant signal between the terminals 17 and 18 of the transducer 12. The frequency and phase of the reverberant signal depends on the phase and frequency of the oscillations of the transducer 12, for example the oscillations arising from a circulating current that can be considered circulating inside the resonant circuit of the transducer 12. The circulating current in the transducer 12 may form a voltage between the terminals 17 and 18. In one embodiment, the voltage formed by the circulating current may be an integral of the circulating current of the transducer 12. Thus, the reverberation signal may be a voltage or a current. The reverberation signal may be received by the controller 20, and the controller 20 may be configured to detect a frequency difference. For example, circuit 28 may receive the reverberant signal as a voltage, and circuit 32 may be configured to detect a frequency difference. In other embodiments, the controller 20 may be configured to use a signal indicative of current. The phase and frequency of the reverberation signal may represent the phase and frequency of the resonant frequency.

One embodiment of the controller 20 may be configured to apply the signal 45 for a portion or a percentage of the half period of the signal 45, such as one or more of the half periods 49 or 50, for example. The controller 20 may include an embodiment that may be configured to detect the frequency difference in at least a portion of the remainder of the half period. During a first half cycle, e.g. half cycle 49, switch 46 may be enabled or closed, and switch 47 may be open or disabled so that part of the half cycle Alternatively, the signal 45 may be applied to the transducer 12 for a certain percentage. For example, during the portion labeled as drive in plot 52. The circuit 41 may be controlled not to drive the transducer 12 during another portion or other percentage of such the same half period, or alternatively the remainder of the half period. For example, the portion labeled HiZ in plot 53. In some embodiments, the output of circuit 41 may be placed in a high impedance state. For example, both switches 46, 47 can be open or disabled, and the controller 20 can form a high output impedance on the terminals 23, 24 or alternatively between them. . In some embodiments, the high impedance can be a value in excess of 1 megohm. The portion of the driving half period while the output of the circuit 41 is not driving the transducer 12 and the controller 20 has a high impedance may be referred to herein as a “HiZ interval”. One embodiment may include that the controller 20 may also be configured to form HiZ spacing elsewhere in the signal 45. For example, the controller 20 may be configured to form the HiZ interval only once within the drive period, for example at the middle of the half cycle or at approximately the beginning of the middle of the drive cycle instead of the end of the half cycle or alternatively It can be configured to form HiZ intervals elsewhere in the same half period, such as near it. The controller 20 may be configured to monitor the reverberant signal formed by the reverberant or resonant oscillation of the transducer 12 during at least part of the HiZ interval, and the controller 20 or alternatively the circuit 32 May be configured to detect. During a second driving half cycle, e.g. half cycle 50, the switch 47 (Fig. 1) can be enabled or closed, and the switch 46 is open or disabled, so that the second drive half cycle It is possible to apply the signal 45 having the opposite polarity to the transducer 12 for a portion or a percentage of. Another part of such the same second drive half cycle or alternatively during the remainder of the second drive half cycle, the circuit 41 may again be put in a state not to drive the transducer 12 to form a HiZ gap or , Alternatively can be placed in a high impedance state, and the controller 20 or alternatively circuit 32 can again determine the frequency difference. In some embodiments, controller 20 or alternatively circuit 32 may be configured to detect a frequency difference of only one of half periods 49 or 50. The controller 20 adjusts the driving frequency to be closer to the resonant frequency after detecting the frequency difference from the reverberation signal received during the first half period and/or detects the frequency difference from the reverberation signal received during the second half period. It can be configured to adjust the driving frequency closer to the resonant frequency later.

The controller 20 may be configured to repeat the drive period 55 for a predetermined number of cycles before completing the transmit phase of the measurement cycle. Those skilled in the art will, in some embodiments, prior to storing sufficient energy for the transducer 12 to reverberate, and accordingly, for a few cycles before starting to form a series of drive cycles 55. You will recognize that it may be necessary to run it.

4 includes graphs illustrating non-limiting examples of embodiments of the phase of the signal 45 and the phase of the reverberation signal for different drive signal frequencies for an exemplary embodiment of the resonant frequency. Plots 56 illustrate signal 25 and plots 57 illustrate the circulating current in transducer 12. The abscissa indicates time, and the ordinate indicates increasing values of the illustrated signals. The abscissa is normalized so that the time interval of the cycle is illustrated to be 100 percent of the period.

The graphs of FIG. 4A illustrate an example in which the driving frequency is substantially the same as the resonance frequency. As illustrated, the phase shift between the two signals is substantially zero.

The graphs of FIG. 4B illustrate an example in which the driving frequency is greater than the resonance frequency. Since the driving frequency is greater than the resonant frequency, the circulating current is later than the signal 45. This is referred to as a positive phase shift or positive phase error, as a current signal occurs after signal 45. The illustrated example shows a positive phase error (40°) of approximately 40 degrees.

The graph of FIG. 4C illustrates an example in which the driving frequency is lower than the resonance frequency. Since the drive frequency is lower than the resonant frequency, the current signal precedes the signal 45, which causes a negative phase shift or negative phase error. The example illustrated in FIG. 4C illustrates a negative phase error (-40°) of approximately 40 degrees.

In one embodiment, the controller 20 may be configured to estimate the phase difference between the circulating current and the signal 45, and thus the phase error. The controller 20 may then be configured to estimate in which direction (increase or decrease) the driving frequency is adjusted to be closer to the resonance frequency using the phase error. One embodiment may include that the controller 20 may be configured to adjust the drive frequency to be substantially equal to the resonant frequency or alternatively to be closer to the resonant frequency. In some embodiments, it may take more than one cycle 55 to adjust the drive frequency to be substantially equal to the resonant frequency.

One embodiment may be configured such that the controller 20 calculates or determines or estimates the phase error between the signal 45 and the circulating current every half cycle of the signal 45, or only part of the drive cycles or alternatively the signal. 45. It may include that which may be configured to calculate or determine or estimate the phase error during a portion of the half periods. Controller 20 or alternatively circuit 32 may have an embodiment that may be configured to receive the reverberant signal of transducer 12 during at least a portion of the HiZ interval. An embodiment of circuit 32 may also be configured to calculate or determine or estimate a phase error during at least a portion of one or more HiZ intervals.

5 is a graph illustrating non-limiting examples of some of the signals formed during operation of one embodiment of the controller 20. Plots 75-77 illustrate voltage 25 for three different frequencies of signal 45, with a corresponding phase error for each identified. Plot 75 illustrates an embodiment of a signal 45 having a drive frequency that substantially matches the resonant frequency. Plots 76 and 77 illustrate one embodiment of a signal 45 having a drive frequency higher or lower than the resonant frequency, respectively. The abscissa indicates time, and the ordinate indicates increasing values of the illustrated signals. Those skilled in the art will know that the voltage 25 represents the drive signal 45 during the portion of the driving cycle or half cycle in which the controller 20 is driving the transducer 12, and the voltage during the HiZ interval or portion of the drive cycle or half cycle ( 25) represents the reverberation signal. In plots 75-77, HiZ intervals are identified in a general manner by dashed circles.

6 is a graph illustrating a non-limiting example of an embodiment of an enlarged view of a portion of FIG. 5 highlighted by one of the dotted circles in FIG. 5. One exemplary embodiment of a method for detecting the frequency difference and/or estimating the phase error is to measure or estimate the curvature of the reverberant signal as representing the phase error between the signal 45 and the circulating current in the transducer 12. It can be. The phase error can be used to detect the frequency difference in addition to the amount of the difference between the two frequencies. This description refers to FIGS. 5 to 7.

The method of detecting the frequency difference may include estimating the curvature of the reverberant signal, such as during a portion of the HiZ interval. In one embodiment, the method can also be used to estimate the phase error. For example, measuring the value of the reverberant signal at different points within the HiZ interval. The time interval between different points and the amplitude of the signal can be used to determine or estimate or calculate the phase error. The controller 20 may be configured to calculate a shape of a waveform of a signal capable of indicating a phase error between the driving frequency and the resonance frequency. For example, the phase error between signal 45 and the circulating current.

In an exemplary embodiment, the controller 20 may be configured to calculate or estimate a shape of a part of a waveform of a reverberant voltage such as the voltage 25, and estimate a phase error using the estimated shape. . The controller 20 may be configured to determine the ratio R between the values of the reverberant signal at different time points of the HiZ interval. In one exemplary embodiment, three different points may be used. The method includes measuring the value of the reverberation signal at two additional points during the HiZ interval after measuring a first point as the value of the reverberation signal at or near the time when the output of the controller 20 becomes a high impedance state. Can include. For example, a first time point or an initial time point may be exemplified by a time TI at which the value of the signal may be the value M0. Examples of embodiments of two additional points are indicated as the value of the signal as a value M1 at time T1 and a value M2 at a different time point such as for example time T2 as illustrated in FIG. 6. Values M1 and M2 are illustrated in a general manner for each embodiment of the signal by arrows. The values for M0 for each of the plots 75-77 may be substantially similar as they occur at or near the initial point TI. The values of M1 and M2 for each plot 75-77 are different because each plot exhibits a different phase error and thus has a different portion of the curve at points T1 and T2. In one exemplary embodiment, the first of the two additional points may be measured at or near the middle of the HiZ interval, and the second of the two additional points is at or approximately the end of the HiZ interval. It can be measured near it or at least before the end. One embodiment may include measuring two additional points evenly distributed over the HiZ interval between the first measurement point and approximately the end or approximately near the HiZ interval. The amplitude of the signal at the three points is illustrated as the corresponding amplitudes M0-M2. The ratio R between the measured values can be calculated as follows:

R= ABS(V2/V1).

In one embodiment, the ratio R can also be calculated as follows,

R=ABS[(M2-M0)/(M1-M0)]

here,

ABS= absolute value,

V1=M1-M0,

V2=M2-M0,

M0 = amplitude at initial point TI, and

M1, M2 = amplitudes at the corresponding points T1, T2.

The ratio R can be used as an indication of the curvature of the measured reverberant signal. In one embodiment, the values M0-M1 can represent the change in values over time intervals, and the values M0-M2 can represent changes in values over different time intervals, so the ratio between the two is measured It can represent the curvature of the waveform of the signal. The curvature may be an indication of the magnitude of the phase error, and the sign of the phase error may be an indication of a direction (plus or minus) of a phase error, such as a direction indicated by symbols in the legend of FIG. 6. For example, if measurements indicate that the value of the signal is going to be positive, the phase error may be negative and the driving frequency may have to be increased, or if the value of the signal is going to be negative, the phase error May be positive and the drive frequency may have to be reduced, or if the value of the signal is being kept close to zero, the phase error may be substantially zero and the drive frequency may have to remain substantially constant.

There may be embodiments where there may be a preferred value of R. The preferred value of the ratio R is usually calculated theoretically. This may depend on the exact timing of the voltage M0-M2, the location of the measurement points TI-T2, and the duration of the HiZ interval as part of the overall drive period. In some embodiments, the value of the ratio R can be used to estimate the phase error.

In one exemplary embodiment, the theoretically calculated preferred value of the ratio R for the illustrated exemplary embodiment of the three measuring points of FIG. 6 was approximately 1.618. When the value of R determined by the controller 20 is greater than 1.618, the phase error may be positive, and the driving frequency may have to be reduced. Alternatively, if the value determined by the controller 20 is less than 1.618, the phase error may be negative, and the driving frequency may have to be increased. In some embodiments, the amount by which the ratio R deviates from the theoretical value may be an indication of the magnitude of the phase error and also of the difference between the driving frequency and the resonant frequency. Thus, the ratio value can indicate the amount by which the driving frequency should be changed and the direction of the change (increase or decrease). In some embodiments, reducing the drive frequency may include slightly delaying the next half cycle of signal 45 and increasing the frequency may include decreasing the width or time of the next half cycle.

FIG. 7 is a graph illustrating another non-limiting example of an embodiment of an enlarged view of a portion of FIG. 5 highlighted by one of the dotted circles in FIG. 5. The phase shift and/or curvature of the signal's waveform can be estimated by measuring the signal value at more points in the HiZ interval. For example, Figure 7 illustrates how to use 5 different points during the HiZ interval. In one exemplary embodiment, the curvature of the signal can be determined from the values of five measurement points.

The method measures the value of the reverberant signal at or near the time when the output of the driver is in a high impedance state, for example at or near the beginning of the HiZ interval, followed by reverberation at four additional different points during the HiZ interval. It may include measuring the value of the signal. An exemplary embodiment of a method of determining a phase error may include sampling the reverberant signal at five different time points during the HiZ interval.

The method may comprise measuring a first point as the value of the reverberation signal at or near the time when the output of the driver enters the HiZ state, and then measuring the value of the reverberation signal at four additional points during the HiZ interval. have. For example, a first time point or an initial time point may be exemplified by a time TI at which the value of the signal may be the value M0. One embodiment may include measuring four additional points evenly distributed over the HiZ interval between the first measurement point and the end or approximately near the end of the HiZ interval. The amplitude of the signal at the five points T0-T4 is illustrated as the corresponding amplitudes M0-M4. Examples of embodiments of four additional points are indicated as a value M1 at time T1, a value M2 at time T2, a value M3 at time T3 and a value M4 at time T4 as illustrated in FIG. 7. Values M1-M4 are illustrated in a general manner by arrows. The ratio R between the measured values can be calculated as follows:

R=ABS[(V4+V3)/(V2+V1)].

In one embodiment, the ratio R may also be calculated as:

R=ABS[(M4+M3-2*M0)/(M2+M1-2*M0)]

here,

ABS= absolute value of the next value,

V1=M1-M0,

V2=M2-M0,

V3=M3-M0,

V4=M4-M0,

M0 = amplitude at the initial point, and

M1, M2, M3, M4 = amplitudes at the corresponding points T1, T2, T3, T4.

In some embodiments, it is believed that measuring the amplitude of the signal at four or more points during the HiZ interval may provide a more accurate calculation of the signal's phase error and/or curvature. Using four or more points may also aid in measurement of other parameters of the transducer 12 such as, for example, parallel capacitance or series impedance of the transducer 12.

The controller 20 may be configured to form a method for detecting the frequency difference. One embodiment of the method comprises driving the transducer 12 during a driving phase at a fixed transmit frequency for a first number of driving periods without detecting a frequency difference and to form a circulating current in the transducer 12. Can include. In some embodiments, the method may be that during the first number of drive cycles the signal 45 may be applied during the full drive half cycle or, optionally, only during a portion of the drive half cycle, with the other portion being the HiZ interval. It may include that. In some embodiments, the method may include that the first number may be in a range of cycles of approximately 3 to 5 (3-5) or approximately 2 to 5 or more (2-5+).

After the first number of driving cycles, the controller 20 controls the signal 45 to include the HiZ interval, detects the frequency difference or alternatively estimates the phase error, and determines the driving frequency to be substantially equal to the reverberation frequency. It can be configured to form a method for controlling. During a portion of the drive half cycle, signal 45 may drive transducer 12 to form a transmitted acoustic signal, and during the HiZ interval controller 20 may be configured to determine or estimate phase error, or It can be configured to estimate the curvature of the waveform of the signal. The controller 20 may include an embodiment configured to reduce the phase error by adjusting the frequency of the next driving signal or alternatively form a phase error to be substantially zero. One embodiment may include that the controller 20 may be configured to adjust the frequency of the next drive signal to be approximately equal to the resonance frequency. The controller 20 adjusts the drive frequency to reduce the phase error in one step, for example during one HiZ interval, or adjusts the drive frequency in fewer steps over multiple drive signal cycles or half cycles. It may have an embodiment configured to adjust. In some embodiments, the controller 20 forms a first adjustment of the drive frequency that results in a greater percentage of the frequency difference, and may be configured to use fewer drive frequency changes during subsequent cycles of the signal 45. have.

8 is a graph illustrating a non-limiting example of an embodiment of the dependence between the phase error and the calculated ratio R. The ratio R can be used as an indication of the curvature of the measured reverberant signal or alternatively as an indication of the phase error. There may be embodiments where there is a preferred value of R. The preferred value of the ratio R is usually calculated theoretically. This may depend on the exact timing of the voltage measurement points M0 to M4 and the duration of the HiZ interval as part of the full drive period or alternatively half the period.

In one exemplary embodiment, for example the exemplary embodiment described in connection with FIG. 8, the theoretically calculated preferred value of the ratio R was approximately 1.963. When the value of R measured or determined by the controller 20 is greater than 1.963, the driving frequency may have to be reduced. Alternatively, when the value measured or determined by the controller 20 is less than 1.963, the driving frequency may be increased. The theoretically calculated preferred value of the ratio R for the example of FIG. 7 may be different from the theoretically calculated preferred value calculated for the illustrative example of FIG. 6, which means that the theoretically calculated preferred value Because it depends on the number of fields, the distance between them, the location of the points, and in some embodiments the formula used.

9 is a diagram of a circuit 80 that can be used to measure a reverberant signal during the HiZ interval, alternatively detect a frequency difference, alternatively determine the curvature of the reverberant signal, or alternatively estimate or determine a phase error. Non-limiting examples of the examples are schematically illustrated. Circuit 80 may also be configured to adjust the drive frequency to be substantially equal to or alternatively closer to the reverberation frequency. The circuit 80 may include a receiver or Rec or receiver circuit 81, an analog-to-digital conversion circuit (ADC) 82 and a control circuit 83. In some embodiments, the circuit 81 may include a circuit 28, such as, for example, an input amplifier 29, or a portion thereof, receiving a reverberant signal during the HiZ interval and forming a signal representing the reverberation signal. Can be used to Circuit 81 may have an embodiment including an attenuator for adjusting the received or amplified signal to a usable value. The attenuator may be omitted in some embodiments.

In some embodiments, circuit 83 may include a digital signal processor and other processors or circuits. Circuit 83 may have an embodiment that may include circuit 82. The circuit 83 can be configured to determine parameters such as the HiZ time interval, the amplitude of the reverberant signal at the measurement points, and can be configured to form the signal 45 to form the HiZ interval, and the information in the algorithm. May be configured to detect a frequency difference and/or determine a phase error, adjust a driving frequency to be substantially a resonant frequency, and/or estimate a curvature of a reverberation signal. In one embodiment, circuit 80 may be part of circuit 32 (FIG. 1).

In one embodiment, circuit 32 (Fig. 1) and/or circuit 80 determines the curvature of the reverberation signal forming information at the measurement points, determines the ratios to the points of the reverberation signal, and drives It may be configured to form a method for adjusting the frequency to be substantially a resonant frequency. For example, one embodiment is configured to determine the amplitude, frequency and phase error of the circulating current by integrating the received reverberation signal and/or interpolating from the measurement points by circuit 32 (FIG. 1) or circuit 80. It can include what can be.

Those skilled in the art are one of the methods for measuring the value of the received signal at various points in the HiZ interval and determining the ratio R is a method for estimating the phase error or alternatively the curvature of the signal and changing the driving frequency. It will be appreciated that it is only a means of describing the exemplary method. Those of skill in the art will recognize that other methods may also be used. For example, the controller may be configured to count the time intervals between the start of the HiZ interval and the signal crossing the threshold. The amount of time it takes for the signal to cross the threshold is an indication of the phase error. Long time intervals may indicate a large negative phase error, and short time intervals may indicate a positive phase error.

10 is a non-limiting example of an embodiment of some results obtained by using an embodiment of the controller 20 and applying an embodiment of a method for adjusting the driving frequency for an embodiment of the transducer 12 It is a graph illustrating Plot 120 illustrates an example of voltage 25, plot 121 illustrates an example of circulating current in transducer 12, and plot 122 illustrates the driving frequency. For the exemplary embodiment, the drive frequency starts around 52 kHz, and the actual transducer resonant frequency is approximately 50 kHz. As illustrated by plot 122, the method adjusts the drive frequency over multiple drive periods to achieve a drive frequency approximately equal to the resonant frequency.

11 schematically illustrates a non-limiting example of some embodiments of a transducer controller 60 that may have embodiments that are alternative embodiments of the controller 20. One embodiment of the controller 60 may be substantially identical to the controller 20 except that the controller 60 has a drive circuit 66, which may be an alternative embodiment of the circuit 41. The controller 60 may be configured to determine a phase error and to adaptively form a driving signal 68 having a frequency and/or phase formed in response to the resonance frequency. The controller 60 may be configured to form a drive signal 68 having three values or states instead of the two values or states described for the drive signal 45 of the controller 20 (FIG. 1 ). . The drive circuit 66 includes switches 46, 47, 67 for forming the three values of the signal 68.

FIG. 12 is a graph illustrating a non-limiting example of an embodiment of some signals generated from the controller 60 that drives the transducer 12 and adjusts the frequency of the signal 68 to be substantially equal to or close to the resonant frequency. to be. Plot 69 illustrates the states of switch 46 and plot 70 illustrates the states of switch 47. Plot 71 illustrates the state of switch 67. Plot 72 illustrates voltage 25. The abscissa indicates time, and the ordinate indicates increasing values of the illustrated signals. This description refers to FIGS. 12 and 13.

The controller 60 will be configured to enable the switch 67 to form a signal 68 such that the controller 60 has a value that is approximately the value of return 22 during a portion of the drive half cycle. Except for what can be, it operates substantially the same as the controller 20. For example, the controller 60 enables the switch 67 at the start of the half cycle or alternatively at the end of the drive half cycle or alternatively at any time during the drive half cycle and enables the switches 46- 47) can be configured to disable. During the other part of the drive half cycle, the controller 60 disables the switch 67, and enables one of the switches 46 or 47, so that the transducer ( 12) can be configured to drive. After the expiration of a part or a certain percentage of the driving half cycle, the controller 60 disables all switches 46, 47, 67 and establishes a HiZ interval, and in the description of the controller 20 and FIGS. 5-11 It may be configured to determine a phase error as described.

Referring to the graphs and operation described in the description of Figures 5-11, those skilled in the art will find that the controller 60 adds the zero value of the voltage 25 as illustrated in the plots 75-77 of Figure 12. Other than that, it will be appreciated that the controller 60 will form similar signals for the voltage 25.

13 is a graph illustrating a non-limiting example of an embodiment of some signals generated from the controller 60 that drives the transducer 12 and adjusts the frequency of the signal 68 to be substantially equal to or close to the resonant frequency. Where the HiZ interval is formed immediately after the switch 67 is closed or enabled during the time interval. Plot 125 illustrates the states of switch 46 and plot 126 illustrates the states of switch 47. Plot 127 illustrates the state of switch 67. Plot 128 illustrates voltage 25. The abscissa indicates time, and the ordinate indicates increasing values of the illustrated signals. These descriptions refer to FIGS. 11 to 13.

In one example of an embodiment, the controller 60 enables the switch 46 at the beginning of the half cycle or alternatively at the end of the drive half cycle and disables the switches 47, 67, so that the first value To drive the transducer 12 and subsequently enable the switch 47 for the subsequent portion of the half cycle and disable the switches 46, 67 to drive the transducer 12 with a first value. Can be configured. The controller 60 subsequently enables the switch 67 and disables the switches 46-47, forming a signal 68 to have a value that is approximately the value of return 22 during the other part of the drive half cycle. Can be configured to The controller 60 forms the HiZ interval after closing the switch 67 and determines the phase error during a portion of the HiZ interval as described in the controller 20 and the description of FIGS. It may have an embodiment configured to detect the difference.

With reference to the graphs and operation described in the description of FIGS. 5-11, those skilled in the art will appreciate that the controller 60 applies voltage 25 to plots 75-77 as illustrated by plot 128 in FIG. It will be appreciated that the controller 60 will form similar signals for voltage 25 during the HiZ interval, other than adding the zero value of.

14 schematically illustrates a non-limiting example of an exemplary embodiment of some of an embodiment of a drive circuit 90, which may be an alternative embodiment of the drive circuits 41 and/or 66. Circuit 90 includes transistors 91 and 93 connected together in a totem pole or series connection. The driving circuit also includes a transistor 94, a transistor 95 and a transistor 92. Transistors 91-92 are P-channel transistors, and transistors 93-95 are N-channel transistors. Transistor 91 has a source connected to receive a DC voltage and a drain of transistor 93, a source of transistor 92 and a drain commonly connected to a first terminal of an optional pump capacitor 97. The source of transistor 93 is connected to return 22 which is also connected to the drain of transistor 94. The source of transistor 94 is commonly connected to the source of transistor 95 and to the second terminal of the optional capacitor 97. The drain of transistor 92 is connected in common to the drain of transistor 95 and to terminal 23.

Circuit 90 may have an embodiment that includes a negative charge pump, which may include a capacitor 97. The charge pump may be configured to generate a negative voltage (-Vi) that may have a magnitude that may be approximately equal to the voltage on the input 21 but may have an opposite sign (eg, negative sign). Such an embodiment of circuit 90 may be an alternative embodiment of circuit 66 of FIG. 11 since driving to a value of approximately zero or alternatively to the value of return 22 is possible.

One embodiment of circuit 90 is when transistors 91, 92, 94 are ON or enabled (when all other transistors are OFF or disabled), circuit 90 It may function similarly to the switch 46 (FIG. 11), which is enabled or closed, and may include the capacitor 97 being charged to approximately the value of the input 21. When transistors 93, 95 are on or enabled (all other transistors are off or disabled) and capacitor 97 is charged to the value of input 21, circuit 90 is enabled or closed. It may function similarly to the switch 47, where the output voltage may be close to the negative value of the value of the input 21. Circuit 90 may include embodiments capable of operating similar to a negative charge pump in addition to functioning as a driver circuit.

When transistors 91 and 94 are on or enabled (all other transistors are off), capacitor 97 is charged to approximately the value on input 21 and the output of circuit 90 is in a high impedance state. It is in (HiZ).

The circuit can have other embodiments. For example, when transistors 91 and 92 are on or enabled (all other transistors are off or disabled), circuit 90 is a switch that is closed or enabled without charging capacitor 97 It can function similarly to 46 (Fig. 11). Also, when transistors 94 and 92 are on or enabled (all other transistors are off or disabled) and capacitor 97 is charged, the circuit 90 is closed or enabled by the switch 46 It can function similarly to (Fig. 11). When all transistors are off, the output of circuit 90 is in a high impedance state (HiZ).

15 schematically illustrates a non-limiting example of some of an embodiment of a three terminal transducer 100. The transducer 100 may include a terminal 17 to which a driving signal may be applied to drive the transducer 100, and may also be used to detect or monitor a circulating current in the transducer 100. It may include a sensing terminal 101.

16 is a graph with plots illustrating a non-limiting example of an embodiment of some of the signals during an embodiment of the drive period of the signal 45 applied to the transducer 100. The transducer 100 may include a sensing terminal 101 that provides a sensing signal for sensing a circulating current. In some embodiments, there may be a coupling in the transducer 100 between the signal 45 and the sense signal. Thus, in some embodiments, the controller 20 may be configured not to use values of the sense signal occurring near the edges of the signal 45. For example, the controller 20 may be configured to blank or mask-off values of the detection signal occurring near edges of the signal 45. For example, the sensing signal may be neglected or blanked during portions of the half period within the percentage of the transition, e.g., approximately 5 to 10 percent (5%-10%) of the period around each transition. have. One embodiment of the controller 20 may be configured to form the HiZ interval for a portion of the half period away from the transitions and to determine the phase error during the HiZ interval.

In another exemplary embodiment of controlling the transducer 100, one embodiment of the controllers 20 or 60 forms a signal 45 or 68 during a substantially full drive half cycle or substantially the full drive cycle. , It can be configured not to form a HiZ gap. The controllers 20 or 60 are configured to receive or monitor the sensing signal during the driving half period or driving period 55, and to blank or mask-off the sensing signal during or near the transitions of the signal 45 or 68. Can be. The controllers 20 or 60 may also be configured to detect a frequency difference or alternatively determine a phase error from the sense signal.

In one embodiment, the controllers 20 or 60 use the sensing signal to sense the circulating current while the drive signal is being used to form the transmitted acoustic signal during the transmit phase and/or detect the circulating current during the active braking phase. It may include what may be configured to be.

17 illustrates an enlarged plan view of a portion of an embodiment of a semiconductor device or integrated circuit 132 formed on a semiconductor die 133. In one embodiment, any one of controllers 20 or 60 may be formed on die 133. Die 133 may also include other circuits not shown in FIG. 17 for simplicity of the drawing. The controller and device or integrated circuit 132 may be formed on the die 133 by semiconductor manufacturing techniques well known to those skilled in the art.

From all the foregoing, one of ordinary skill in the art would have one embodiment of a method of forming a transducer controller:

Configuring a transducer controller, such as controller 20 or 60, to form a drive signal, for example signal 45 or 68, at a first frequency forming a drive period and a drive half period;

Configuring the transducer controller to drive the transducer with the drive signal during the first portion of the drive half cycle;

Configuring the transducer controller to sense a reverberant voltage formed by the transducer during a second portion of the driving half cycle;

Configuring the transducer controller to measure portions of the reverberant voltage and estimate a phase error between the first frequency and the resonant frequency of the transducer; And

It will be appreciated that it may include configuring the transducer controller to adjust the first frequency to a second frequency that reduces the phase error.

Another embodiment of the method may include configuring the transducer controller to incrementally adjust the first frequency to the second frequency during a first number of subsequent drive cycles.

The method may have embodiments that may include configuring the transducer controller to calculate the curvature of the waveform of the voltage and estimate the phase error from the curvature.

An embodiment may include configuring the transducer controller to adjust the first frequency to a second frequency that is substantially the same as the resonant frequency of the transducer.

Another embodiment may include configuring the transducer controller to form a drive signal for driving the transducer only during the first portion of the drive half cycle.

The method has embodiments that may include configuring the transducer controller to form a HiZ interval during a second half period and sense a reverberant voltage during the HiZ interval.

An embodiment may include configuring the transducer controller to measure the value of the reverberation at one or more time intervals during the second half period and determine a ratio of the one or more values.

An embodiment may include comparing the ratio with the theoretically calculated value, determining a difference between the ratio and the theoretically calculated value, and determining how much to adjust the first frequency using the difference.

One embodiment of the method may include configuring the transducer controller to form a drive signal having a value of substantially zero during a third portion of the half cycle, the third portion after the first portion and the second portion. It is formed either before or after the second part.

Those of skill in the art would appreciate one embodiment of a method of forming a transducer controller:

Configuring the transducer controller to form a drive signal at a first frequency forming a drive period and a drive half period;

Configuring the transducer controller to drive the transducer with the drive signal during the first portion of the drive half cycle;

Configuring the transducer controller to sense a reverberation signal formed by the transducer in response to the driving signal in a second portion of the driving half cycle;

Configuring the transducer controller to determine a phase error between the first frequency and the frequency of the reverberant signal; And

It will be appreciated that it may include configuring the transducer controller to adjust the first frequency to a second frequency that reduces the phase error.

One embodiment of the method may include forming a transducer controller to include a non-transitory computer readable medium having a program stored therein.

Another embodiment may include forming a transducer controller to operate according to a program.

One embodiment may include configuring the transducer controller to form a second immediately following period of the drive signal, the second period having a second duration.

In one embodiment, the method may include configuring the transducer controller to measure values of the reverberant signal at a plurality of times during the second portion of the driving half period.

One embodiment of the method may include configuring a transducer controller to form a ratio of two or more of the values and compare the ratio to a theoretical ratio value.

Another embodiment may include determining a time for a reverberant signal value to substantially cross a threshold and configuring the transducer controller to compare the time to a theoretically determined time.

An embodiment may include configuring the transducer controller to place the outputs of the transducer controller in a high impedance state during the second portion of the driving half cycle and to sense the reverberant voltage during the high impedance state.

Those of skill in the art would appreciate one embodiment of a method of forming a transducer controller:

Configuring the transducer controller to form a drive signal at a first frequency forming a drive period and a drive half period;

Configuring the transducer controller to drive the transducer with the drive signal during at least a first portion of the drive half cycle;

In the second part of the driving half cycle, configuring the transducer controller to detect the reverberation signal formed by the transducer in response to the driving signal, wherein the transducer controller ignores the reverberation signal in response to transitions of the driving signal. Configured to, the configuring step;

Configuring the transducer controller to determine a phase error between the first frequency and the frequency of the reverberant signal; And

It will be appreciated that it may include configuring the transducer controller to adjust the first frequency to a second frequency closer to the reverberant frequency of the transducer than the first frequency.

One embodiment of the method may include configuring the transducer controller to mask-off the reverberant signal at approximately the transitions of the drive signal.

Another embodiment may include forming the second frequency to be substantially the same as the reverberation frequency.

In view of all the foregoing, it is clear that novel devices and methods are disclosed. Among other features, the difference between the drive frequency and the resonant frequency of the transducer (or alternatively the difference between the phase of the drive signal and the phase of the transducer resonance frequency) is periodically determined, among other features, during the cycle of transmitting the measurement signal from the transducer A control circuit or controller to detect and adjust the frequency of the drive signal to reduce the phase error or, in an alternative embodiment, adjust the frequency of the signal 45 to be substantially equal to the resonant frequency of the transducer 12 during the transmission cycle. It includes forming. Adjusting the frequency of the signal 45 during the transmission cycle, for example half a period, improves the sensitivity of the transducer 12 and facilitates measuring larger distances using the transducer 12. This may also facilitate forming a wider detectable range in which the transducer can be used.

The subject matter of the descriptions is described in certain preferred and exemplary embodiments, but the foregoing drawings and their descriptions are intended to depict only typical and non-limiting examples of the subject matter embodiments and are therefore considered to limit their scope. It should not be, and it is clear that many alternatives and variations will be apparent to those skilled in the art. As will be appreciated by those skilled in the art, the exemplary form of the measurement system and associated controllers is used as a means to describe the operating method of determining or estimating phase error, detecting frequency difference, and adjusting drive frequency.

As the claims below indicate, aspects of the invention may lie in less than all features of a single disclosed embodiment described above. Accordingly, the claims expressed below are expressly included within this detailed description of the drawings, with each claim standing on its own as a separate embodiment of the invention. Moreover, even though some embodiments described herein include some features included in other embodiments, but not other features, as those skilled in the art will understand, combinations of features of different embodiments are within the scope of the present invention. And it is intended to form different embodiments.

Claims (5)

As a method of forming a transducer controller,
Configuring the transducer controller to form a drive signal at a first frequency forming a drive period and a drive half-period;
Configuring the transducer controller to drive the transducer with the drive signal during a first portion of a drive half cycle;
Configuring the transducer controller to sense a reverberation voltage formed by the transducer during a second portion of the driving half cycle;
Configuring the transducer controller to measure portions of the reverberant voltage and estimate a phase error between the first frequency of the drive signal and a resonant frequency of the transducer; And
And configuring the transducer controller to change the first frequency of the drive signal to a second frequency that reduces the phase error. The method of claim 1, wherein configuring the transducer controller to measure the reverberant voltage comprises configuring the transducer controller to calculate a curvature of the waveform of the voltage and estimate the phase error from the curvature. , Way. The method of claim 1, wherein configuring the transducer controller to sense the reverberation voltage comprises: forming a HiZ interval during a part of a driving half cycle and configuring the transducer controller to sense the reverberation voltage during the HiZ interval. Containing, method. As a method of forming a transducer controller,
Configuring the transducer controller to form a drive signal at a first frequency forming a drive period and a drive half period;
Configuring the transducer controller to drive the transducer with the drive signal during a first portion of a drive half cycle;
Configuring the transducer controller to sense a reverberation signal formed by the transducer in response to the driving signal in a second portion of the driving half cycle;
Configuring the transducer controller to determine a phase error between the first frequency of the drive signal and the frequency of the reverberation signal; And
And configuring the transducer controller to change the first frequency of the drive signal to a second frequency that reduces the phase error. As a method of forming a transducer controller,
Configuring the transducer controller to form a drive signal at a first frequency forming a drive period and a drive half period;
Configuring the transducer controller to drive the transducer with the drive signal during at least a first portion of the drive half cycle;
In a second part of the driving half cycle, configuring the transducer controller to detect a reverberation signal formed by the transducer in response to the driving signal, wherein the transducer controller includes a transition of the driving signal. ), configured to ignore the reverberant signal in response to;
Configuring the transducer controller to determine a phase error between the first frequency of the drive signal and the frequency of the reverberation signal; And
And configuring the transducer controller to change the first frequency of the drive signal to a second frequency closer to the reverberant frequency of the transducer than the first frequency.

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