JP5320803B2 - Vibration actuator driving device and optical apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibration actuator driving device that performs suitable control. <P>SOLUTION: The vibration actuator driving device includes a driving circuit 41 for generating a driving signal for driving a vibration actuator 30, a sensor 46 provided in the vicinity of the driving circuit 41 to detect the temperature, and a control section 43 for correcting the driving signal according to the output of the sensor 46. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a vibration actuator driving device and an optical apparatus including the same.

  The vibration actuator is provided in an interchangeable lens of a camera, for example, and is put into practical use as a drive motor that drives an autofocus lens. In such a vibration actuator drive device, a technique for correcting the drive frequency when the mechanical resonance frequency of the vibrator fluctuates due to temperature or the like is disclosed (see Patent Document 1).

Japanese Patent Laid-Open No. 7-15984

  In such a vibration actuator, during driving, the temperature of the piezoelectric element rises due to heat generated by friction of an elastic body constituting the vibration actuator, and the resonance frequency of the piezoelectric element changes. Here, in the above-described technique, the temperature sensor is bonded to the elastic body constituting the vibration actuator, and the temperature of the elastic body is measured to correct the drive frequency of the vibration actuator and to control the speed of the vibration actuator. . However, in the above-described technique, the temperature sensor is directly bonded to the elastic body constituting the vibration actuator, so that wiring for connecting the power supply and output of the temperature sensor to the control circuit of the vibration actuator driving device is required. Furthermore, since the wiring is routed outside the substrate of the vibration actuator driving device, noise may be added to the output of the temperature sensor. The problem to be solved by the present invention is to provide a vibration actuator driving apparatus capable of suitable control and an optical apparatus including the vibration actuator driving apparatus.

The invention according to claim 1 is a drive circuit (41) for generating a drive signal for driving the vibration actuator (30), and a sensor (46) provided in the vicinity of the drive circuit (41) for detecting temperature. And a control unit (43) that converts the output of the sensor (46) into a temperature of the vibration actuator (30), and the control unit (43) depends on the converted temperature of the vibration actuator (30). The vibration actuator driving apparatus is characterized by correcting the driving signal .

The invention according to claim 2 is a drive circuit (41) for generating a drive signal for driving the vibration actuator (30), and a sensor (46) provided in the vicinity of the drive circuit (41) for detecting temperature. A substrate (48) on which the drive circuit (41) is mounted, an independent circuit mounted on the substrate (48) and independent of the drive circuit (41), and provided in the vicinity of the independent circuit, An independent circuit sensor (46a) for detecting the temperature of the independent circuit, and the drive signal is corrected using a difference between the output of the sensor (46) and the output of the independent circuit sensor (46a). It is a vibration actuator drive device characterized by including a control part (43) .

The invention according to claim 3, a vibration actuator driving device according to 請 Motomeko 2, wherein the sensor (46) shall be provided in a position closer to the drive circuit (41) than the independent circuit A vibration actuator driving device characterized by the above.

The invention according to claim 4 is the vibration actuator driving apparatus according to claim 1 , wherein the temperature of the vibration actuator (30) converted by the control unit (43) and the frequency of the vibration actuator (30). A vibration actuator drive comprising a memory (47) storing a relationship with characteristics, wherein the control section (43) corrects the drive signal using information stored in the memory (47). Device.

The invention according to claim 5 is the vibration actuator drive device according to any one of claims 1 to 4 , wherein the drive circuit (41) drives the vibration actuator (30). A vibration actuator driving device having an inductor (51, 61) for generating a voltage for detecting the temperature of the inductor (51, 61) directly or indirectly. It is.

The invention according to claim 6 is the vibration actuator drive apparatus according to claim 5 , wherein the drive circuit (41) is a switching element (52, 53) for switching a current flowing through the inductor (51, 61). 62, 63), and the sensor (46) detects the temperature of the switching element (52, 53, 62, 63) directly or indirectly. .

The invention according to claim 7 is the vibration actuator driving device according to claim 5 or 6 , wherein the inductor (51, 61) is a capacitor component (31a, 31b) of the vibration actuator (30). And a resonant actuator driving device.

  The invention according to claim 8 is an optical apparatus comprising the vibration actuator driving device according to any one of claims 1 to 7 and a vibration actuator.

  In the present invention, it is possible to provide a vibration actuator driving device capable of suitable control.

<< First Embodiment >>
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a first embodiment of the invention will be described with reference to the drawings.
FIG. 1 is a main part configuration diagram showing a camera system 1 of the first embodiment. The camera system 1 of the present embodiment includes a camera body 10 having an image sensor 11 and a lens barrel 20 having a lens 21. Examples of the camera system 1 include, but are not limited to, a single-lens reflex digital camera, a video camera, a mobile phone camera, and a single-lens reflex camera using a silver salt film.

  The lens barrel 20 is an interchangeable lens that can be attached to and detached from the camera body 10. In the present embodiment, the lens barrel 20 is an interchangeable lens. However, the present invention is not limited to this. For example, the lens barrel 20 may be a lens barrel integrated with the camera body. The lens barrel 20 includes a lens 21, a cam barrel 22, gears 23 and 24, an ultrasonic motor 30, an ultrasonic motor driving device 40, and the like. The ultrasonic motor 30 is used as a driving source for driving the lens 21 during the focusing operation of the camera system 1, and the driving force obtained from the ultrasonic motor 30 is transmitted to the cam cylinder 22 via the gears 23 and 24. It is done. The lens 21 is held by the cam barrel 22 and is a focus lens that moves in the optical axis direction by the driving force of the ultrasonic motor 30 to adjust the focus.

  The ultrasonic motor 30 of the present embodiment is a rotary ultrasonic motor, and includes an annular vibrator and an annular relative motion member (also referred to as a rotor or a mover). An annular vibrator is composed of an annular elastic body and an annular piezoelectric element (electromechanical energy conversion element) bonded to the elastic body. The annular piezoelectric element has electrodes appropriately polarized in the circumferential direction. (For example, about 12 poles). Then, in the piezoelectric element polarized in this way, two AC signals whose phases are shifted by 90 degrees from the ultrasonic motor driving device 40 are combined with their inverted signals, and alternately alternated for each polarized electrode. Supplied. As a result, the piezoelectric element vibrates, a traveling wave vibration is generated in the elastic body, and the relative motion member that is in pressure contact with the elastic body is rotationally driven in response to the traveling wave vibration generated in the elastic body.

  FIG. 2 is a diagram illustrating a configuration of the ultrasonic motor driving device 40 according to the first embodiment. As shown in FIG. 2, the ultrasonic motor driving device 40 includes a drive circuit 41, a DC power supply circuit 42, a microcomputer 43, an MR processing sensor 44, a temperature sensor 46, and a memory 47. These are mounted on the substrate 48 for the ultrasonic motor driving device.

  The drive circuit 41 is electrically connected to the piezoelectric elements 31a and 31b constituting the ultrasonic motor 30 so that two AC signals whose phases are shifted by 90 degrees can be supplied to the piezoelectric elements 31a and 31b, respectively. It has become. The piezoelectric elements 31 a and 31 b constitute a capacitor component in the ultrasonic motor 30. In FIG. 2, for the sake of simplicity, it is assumed that two AC signals supplied from the drive circuit 41 and whose phases are shifted by 90 degrees are supplied to the two piezoelectric elements 31 a and 31 b. However, the piezoelectric element 31a means all polarized piezoelectric elements to which one AC signal and its inverted signal are supplied. Similarly, the piezoelectric element 31b means all polarized piezoelectric elements to which the other AC signal and its inverted signal are supplied.

  FIG. 3 is a diagram showing a circuit configuration of the drive circuit 41 of the first embodiment. As illustrated in FIG. 3, the drive circuit 41 includes a first AC signal supply circuit 50 and a second AC signal supply circuit 60, and the first AC signal supply circuit 50 includes a transformer 51, MOSFETs 52 and 53, and diodes 54 and 55. , And an inverter 56. Similarly, the second AC signal supply circuit 60 includes a transformer 61, MOSFETs 62 and 63, diodes 64 and 65, and an inverter 66, similar to the first AC signal supply circuit 50. The transformer 51 of the first AC signal supply circuit 50 and the transformer 61 of the second AC signal supply circuit 60 form a resonance circuit with the piezoelectric elements 31a and 31b, respectively.

  Further, as shown in FIG. 3, the first AC signal supply circuit 50 and the second AC signal supply circuit 60 constituting the drive circuit 41 are supplied with DC currents I 1 and I 2 from the DC power supply circuit 42 and drive frequency from the microcomputer 43. Pulse signals P1 and P2 are supplied respectively.

  The DC power supply circuit 42 may be a DC / DC converter, for example, and supplies DC currents I1 and I2 to the drive circuit 41.

  The microcomputer 43 is a main CPU for controlling the ultrasonic motor driving device 40. The microcomputer 43 includes a pulse generation circuit and a switching control circuit, and thereby supplies drive frequency pulse signals P1 and P2 to the drive circuit 41. Further, the microcomputer 43 is configured to send the rotational speed data of the ultrasonic motor 30 sent by the MR sensor processing circuit 44 and the temperature data measured by the temperature sensor 46. The drive frequency pulse signal supplied to the drive circuit 41 can be controlled based on the rotational speed data and temperature data of the ultrasonic motor 30. The control of the drive frequency pulse signal based on the temperature data of the temperature sensor 46 will be described in detail later.

  The MR sensor processing circuit 44 detects the rotational speed of the ultrasonic motor 30 measured by the MR sensor 45 and outputs it to the microcomputer 43. As shown in FIG. 2, the MR sensor 45 is provided in the vicinity of the ultrasonic motor 30, and MR sensor processing on the ultrasonic motor drive device substrate 48 is performed by wiring provided outside the ultrasonic motor drive device substrate 48. The circuit 44 is electrically connected.

  The temperature sensor 46 is a thermistor, for example, and is provided in the vicinity of the drive circuit 41 on the ultrasonic motor drive device substrate 48 as shown in FIG. 2, and detects the temperature generated from the drive circuit 41. The detected temperature is sent to the microcomputer 43. The installation position of the temperature sensor 46 is not particularly limited as long as it is in the vicinity of the drive circuit 41. For example, in the drive circuit 41, in the vicinity of the transformers 51 and 61 or the MOSFETs 52, 53, 62, and 63. It can be installed in the vicinity. By installing the temperature sensor 46 in the vicinity of the transformers 51, 61 and the MOSFETs 52, 53, 62, 63, the heat generation of the transformers 51, 61 and the MOSFETs 52, 53, 62, 63 when the drive circuit 41 is driven. It can be detected directly. As a method of installing the temperature sensor 46 in the vicinity of the transformers 51 and 61 and the MOSFETs 52, 53, 62, and 63, there is a method of mounting the temperature sensor 46 on a wiring pattern to which these are connected.

  The memory 47 stores the relationship between the temperature in the vicinity of the drive circuit 41 measured by the temperature sensor 46 and the resonance frequency and drive frequency (frequency of the alternating voltage applied to the piezoelectric element) of the piezoelectric element. Can be transmitted to the microcomputer 43.

  Such an ultrasonic motor driving device 40 operates as follows. That is, first, the phase of the driving frequency f corresponding to the desired rotational speed N is 90 degrees so that the ultrasonic motor 30 is rotated at the desired rotational speed N by the pulse generation circuit and the switching control circuit provided in the microcomputer 43. Two shifted pulse signals P1 and P2 are output. The output pulse signals P1 and P2 are supplied from the microcomputer 43 to the first AC signal supply circuit 50 and the second AC signal supply circuit 60 constituting the drive circuit 41, respectively, and the MOSFETs 52 and 62 are turned on and off. By turning on and off the MOSFETs 52 and 62, boosted signals C1 and C2 having the same frequency f as the pulse signals P1 and P2 are generated on the secondary winding side of the transformers 51 and 61, respectively.

  The boosted signals C1 and C2 generated on the secondary winding side are supplied to the piezoelectric elements 31a and 31b of the ultrasonic motor 30, and the piezoelectric elements 31a and 31b vibrate at the same frequency f as the pulse signal. The signals C1 and C2 are 90 degrees out of phase. As described above, the piezoelectric element 31a is a set of a plurality of polarized piezoelectric elements, and is a set of piezoelectric elements to which the signal C1 and the signal -C1 are supplied. Similarly, the piezoelectric element 31b is a set of a plurality of polarized piezoelectric elements, and is a set of piezoelectric elements to which the signal C2 and the signal -C2 are supplied. The signal -C1 and the signal -C2 are signals that are wired with the ground and each signal wiring reversed with respect to the signals C1 and C2. Then, when the signals C1 and C2 are supplied to the piezoelectric elements 31a and 31b in this way, traveling waves are generated in the elastic bodies joined to the piezoelectric elements 31a and 31b, and the relative motion is brought into pressure contact with the elastic bodies. The member receives the vibration of the traveling wave generated in the elastic body and is rotationally driven at a rotational speed N corresponding to the driving frequency f.

  Further, in the present embodiment, when the ultrasonic motor 30 is driven in this way, on the series circuit of the secondary windings of the transformers 51 and 61 and the piezoelectric elements 31a and 31b in the cycle of the driving frequency f. By turning off the MOSFETs 53 and 63 provided for the predetermined period, free vibrations generated between the transformers 51 and 61 and the piezoelectric elements 31a and 31b can be suppressed.

  FIG. 4 is a graph showing the temperature transition of the ultrasonic motor 30, the vicinity of the drive circuit 41, and the end of the ultrasonic motor driving device substrate 48 when the ultrasonic motor 30 is driven and stopped. In addition, the graph shown in FIG. 4 is the data which performed each measurement under room temperature (25 degreeC). As shown in FIG. 4, when the driving of the ultrasonic motor 30 is started, the temperature of the ultrasonic motor 30 (that is, the temperature of the piezoelectric element of the ultrasonic motor 30) rises, while the driving of the ultrasonic motor 30 is stopped. Then, the temperature of the ultrasonic motor 30 falls. Here, the reason why the temperature of the ultrasonic motor 30 rises due to the driving of the ultrasonic motor 30 is, for example, heat generation due to friction of an elastic body constituting the ultrasonic motor 30, and the piezoelectric constituting the ultrasonic motor 30. For example, the temperature of the element increases.

  FIG. 5 is a graph showing the relationship between the temperature of the piezoelectric element constituting the ultrasonic motor 30, the resonance frequency of the piezoelectric element and the driving frequency (frequency of the alternating voltage applied to the piezoelectric element). As shown in FIG. 5, the resonance frequency and the drive frequency of the piezoelectric element constituting the ultrasonic motor 30 change as the temperature of the piezoelectric element changes. Therefore, even if the signals C1 and C2 (driving frequency) supplied from the ultrasonic motor driving device 40 to the ultrasonic motor 30 are constant, the temperature of the piezoelectric element changes due to the driving of the ultrasonic motor 30. The rotational speed of the ultrasonic motor 30 will change. Therefore, when driving the ultrasonic motor 30 in the ultrasonic motor driving device 40, it is possible to detect a temperature change of the piezoelectric element constituting the ultrasonic motor 30 and correct the driving frequency according to the temperature change. desirable.

  Here, the drive of the ultrasonic motor 30 is started by referring to the temperature change of the ultrasonic motor 30 in FIG. 4 (that is, the temperature change of the piezoelectric element of the ultrasonic motor 30) and the temperature change in the vicinity of the drive circuit 41. Then, since the drive circuit 41 is also driven as in the ultrasonic motor 30, it can be confirmed that the drive circuit 41 also generates heat and the temperature in the vicinity of the drive circuit 41 also rises. Further, when the driving of the ultrasonic motor 30 is stopped, the drive circuit 41 is also stopped driving similarly to the ultrasonic motor 30, so that it can be confirmed that the temperature in the vicinity of the drive circuit 41 also decreases. That is, it can be said that the temperature behavior is approximated between the piezoelectric element of the ultrasonic motor 30 and the vicinity of the drive circuit 41.

  Of the elements constituting the drive circuit 41, the transformers 51 and 61 and the MOSFETs 52, 53, 62, and 63 generate a large amount of heat when the drive circuit 41 is driven. Therefore, by installing the temperature sensor 46 in the vicinity of the drive circuit 41, the temperatures of the transformers 51 and 61 and the MOSFETs 52, 53, 62, and 63 are detected directly or indirectly depending on the installation position. . For example, when the temperature sensor 46 is installed in the vicinity of the transformer 51, the temperature of the transformer 51 is directly detected, and the temperatures of the transformer 61 and the MOSFETs 52, 53, 62, and 63 are detected indirectly. Become.

  In this embodiment, the temperature sensor 46 is installed in the vicinity of the drive circuit 41 to detect the temperature generated from the drive circuit 41, and the temperature of the piezoelectric element of the ultrasonic motor 30 is detected using this temperature. It can be measured indirectly. As shown in FIG. 4, the temperature near the drive circuit 41 and the temperature of the ultrasonic motor 30 are similar in temperature change behavior, but the absolute amount of temperature change is different. Therefore, when the temperature value measured by the temperature sensor 46 is sent to the microcomputer 43, the microcomputer 43 converts the temperature value into the temperature of the piezoelectric element of the ultrasonic motor 30. Then, the microcomputer 43 reads from the memory 47 the temperature in the vicinity of the drive circuit 41 measured by the temperature sensor 46 as shown in FIG. 5 (that is, the temperature of the piezoelectric element constituting the ultrasonic motor 30) and the resonance of the piezoelectric element. Correlation data between the frequency and the drive frequency is read, and based on this, the frequencies of the signals C1 and C2 supplied from the drive circuit 41 to the ultrasonic motor 30 are sequentially corrected.

  According to the present embodiment, the temperature sensor 46 is provided in the vicinity of the drive circuit 41 on the ultrasonic motor driving device 40 by adopting the configuration as described above. Wiring between the ultrasonic motor driving device 40 and the ultrasonic motor 30, which is required when the two are bonded, can be eliminated, and external noise can be removed. Further, the step of bonding the temperature sensor 46 to the sonic motor 30 is not necessary. Furthermore, it is possible to appropriately detect changes in the resonance frequency and the drive frequency due to temperature changes of the vibration actuator, while eliminating the need for wiring outside the substrate, thereby enabling suitable control.

  In addition, as can be confirmed from FIG. 4, the temperature behavior of the ultrasonic motor 30 and the vicinity of the drive circuit 41 is approximate, so that the temperature change of the ultrasonic motor 30 can be detected appropriately, and the temperature change Accordingly, the drive frequency can be corrected appropriately. In addition, as is apparent from FIG. 4, since the temperature change in the vicinity of the drive circuit 41 due to the driving and stopping of the ultrasonic motor is relatively large, it is necessary to use a highly accurate sensor as the temperature sensor 46. Absent.

<< Second Embodiment >>
Next, a second embodiment of the present invention will be described. Except as described below, the second embodiment of the present invention has the same configuration as that of the first embodiment described above, and exhibits the same effects.

  FIG. 6 is a diagram illustrating a configuration of an ultrasonic motor driving device 40a according to the second embodiment. In the ultrasonic motor driving device 40a of the second embodiment, in addition to the temperature sensor 46 provided in the vicinity of the drive circuit 41, a temperature sensor 46a is provided in the vicinity of the end portion of the substrate 48 for the ultrasonic motor driving device. This is different from the first embodiment. That is, the temperature sensor 46 a is arranged at a position away from the temperature sensor 46 and the drive circuit 41. This is because the temperature sensor 46a is used to detect the temperature of the substrate 48 for the ultrasonic motor drive device that is less affected by the drive circuit 41.

  In the second embodiment, when the temperature of the ultrasonic motor 30 is indirectly measured and the microcomputer 43 sequentially corrects the frequencies of the signals C1 and C2 supplied from the drive circuit 41 to the ultrasonic motor 30, the drive circuit In addition to the measurement value of the temperature sensor 46 provided in the vicinity of 41, the measurement value of the temperature sensor 46a provided in the vicinity of the end of the ultrasonic motor driving device substrate 48 is also used. That is, the difference between the measured value of the temperature sensor 46 and the measured value of the temperature sensor 46a is taken, and the correction is sequentially performed based on this value.

  In addition to the case where components that generate heat other than the drive circuit 41 are mounted on the substrate 48 for the ultrasonic motor drive device, there are components other than the drive circuit 41 that are supplied with direct-current power by the direct-current power circuit 42. The amount of heat generated by the DC power supply circuit 42 may vary due to the variation. In such a case, the behavior of the temperature change between the drive circuit 41 and the ultrasonic motor 30 may not approximate. On the other hand, according to the second embodiment, in addition to the temperature sensor 46 provided in the vicinity of the drive circuit 41, the temperature sensor 46a is provided in the vicinity of the end portion of the ultrasonic motor driving device substrate 48, and these measured values are measured. By taking these differences, the above problem can be effectively solved. The temperature sensor 46 a is also preferably installed in the vicinity of a component that generates heat other than the drive circuit 41 or the DC power supply circuit 42. In this case, it is preferable that the temperature sensor 46a is used to detect the temperatures of components, circuits, etc. that generate heat other than the drive circuit 41, and the difference between the detected values of the temperature sensor 46 and the temperature sensor 46a is taken. This is because by taking the difference between the detection values, it is possible to eliminate the influence of heat-generating components other than the drive circuit 41.

  The embodiment described above is described for facilitating the understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

FIG. 1 is a main part configuration diagram showing a camera system 1 of the first embodiment. FIG. 2 is a diagram illustrating a configuration of the ultrasonic motor driving apparatus according to the first embodiment. FIG. 3 is a diagram illustrating a circuit configuration of the drive circuit according to the first embodiment. FIG. 4 is a graph showing the temperature transition of the ultrasonic motor, the vicinity of the drive circuit, and the substrate end portion of the ultrasonic motor driving device when the ultrasonic motor is driven and stopped. FIG. 5 is a graph showing the relationship between the temperature of the piezoelectric element constituting the ultrasonic motor, and the resonance frequency and driving frequency of the piezoelectric element. FIG. 6 is a diagram showing the configuration of the ultrasonic motor driving apparatus according to the second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Camera system 10 ... Camera body 20 ... Lens barrel 30 ... Ultrasonic motor 31a, 31b ... Piezoelectric element 40, 40a ... Ultrasonic motor drive device 41 ... Drive circuit 42 ... DC power supply circuit 43 ... Microcomputer 46, 46a ... Temperature Sensor 47 ... Memory

Claims (8)

A drive circuit for generating a drive signal for driving the vibration actuator;
A sensor provided in the vicinity of the drive circuit for detecting temperature;
A controller that converts the output of the sensor into a temperature of the vibration actuator;
Wherein the control unit, the vibration actuator driving device, wherein the benzalkonium to correct the driving signal according to the temperature of converted the vibration actuator. A drive circuit for generating a drive signal for driving the vibration actuator;
A sensor provided in the vicinity of the drive circuit for detecting temperature;
A substrate on which the drive circuit is mounted;
An independent circuit mounted on the substrate and independent of the drive circuit;
An independent circuit sensor for detecting the temperature of the independent circuit provided in the vicinity of the independent circuit;
A vibration actuator driving apparatus comprising: a control unit that corrects the driving signal using a difference between an output of the sensor and an output of the independent circuit sensor. A vibration actuator driving apparatus according to claim 2,
The vibration actuator driving apparatus, wherein the sensor is provided at a position closer to the driving circuit than the independent circuit. The vibration actuator driving device according to claim 1,
A memory storing the relationship between the temperature of the vibration actuator converted by the control unit and the frequency characteristic of the vibration actuator;
The control unit corrects the drive signal using information stored in the memory, and the vibration actuator drive device. The vibration actuator driving device according to any one of claims 1 to 4 , wherein:
The drive circuit includes an inductor that generates a voltage for driving the vibration actuator;
The vibration actuator driving apparatus characterized in that the sensor detects the temperature of the inductor directly or indirectly. The vibration actuator driving device according to claim 5 ,
The drive circuit has a switching element that switches a current flowing through the inductor,
The vibration actuator driving device characterized in that the sensor directly or indirectly detects the temperature of the switching element. The vibration actuator driving device according to claim 5 or 6 , wherein
The vibration actuator driving apparatus characterized in that the inductor constitutes a resonance circuit with a capacitor component of the vibration actuator.   An optical apparatus comprising the vibration actuator drive device according to any one of claims 1 to 7 and a vibration actuator.

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