JP4859216B2 - Imaging device and vibration device - Google Patents

Description

  The present invention relates to a technique for detecting a failure of a vibration apparatus using a piezoelectric element.

  Electronic imaging devices (hereinafter referred to as cameras) typified by digital still cameras and video cameras are rapidly spreading because of their immediacy and high compatibility with personal computers. These cameras obtain image data by subjecting a subject image to photoelectric conversion with an image sensor. As a general minimum configuration, an optical element such as a low-pass filter disposed in front of the image sensor, a photographing optical system, and the image sensor. It consists of.

  In the above camera, for example, when a foreign substance such as dust adheres to the optical element, the foreign substance itself is reflected in the image and the image quality is deteriorated. For this reason, various techniques for removing foreign substances adhering by vibrating the optical element have been proposed, and have recently been put into practical use (see Patent Document 1).

  By the way, when removing the adhering foreign matter by vibrating the optical element as described above, a vibration apparatus using a piezoelectric element is generally used as a device for vibrating the optical element. For example, when a vibration device using this piezoelectric element fails, the drive control device itself may be seriously damaged by an abnormal operation of the vibration device unless the drive control device is stopped immediately.

  As an electrical failure of a general actuator using a piezoelectric element, there are an open mode failure and a short-circuit mode failure. As the open mode failure, for example, stress destruction of the piezoelectric element itself, contact failure or disconnection of the connector or harness, and the like can be considered. Examples of short-circuit mode failures include those caused by ionization migration of the electrode surface due to humidity of the laminated piezoelectric element, and those in which the harness comes into contact with the chassis or the like while the harness is being driven and the coating breaks and short-circuits.

As a method of detecting these failures, a method of detecting an abnormality from a charging time and a voltage level by monitoring a charging voltage based on the piezoelectric element having a capacitance when the actuator is energized to the piezoelectric element. Is known (see Patent Document 2).
JP 2003-333391 A JP 2002-134804 A

  However, in the above technique, when the piezoelectric element is driven at a high speed, the electrostatic capacity of the piezoelectric element itself changes as the pulse driving frequency increases, so the charging time is not constant. Moreover, it is necessary to change the voltage applied to the piezoelectric element with respect to the required energy amount. Therefore, it is necessary to set a plurality of voltage thresholds for determining a failure. In other words, when the piezoelectric element itself is driven at a high speed and is driven while changing the applied voltage, the setting of the voltage threshold for judging the charging time and failure is complicated, and the reliability of failure detection is reduced. There were problems and increased processing time.

  Accordingly, the present invention has been made in view of the above-described problems, and an object of the present invention is to easily perform failure detection of a vibration device using a piezoelectric element with a simple configuration.

In order to solve the above-described problems and achieve the object, an imaging apparatus according to the present invention includes an imaging element that performs photoelectric conversion of a subject image, an optical element that is disposed in front of the imaging element, and vibrates the optical element. A vibration device comprising a piezoelectric element to be driven, a driving means for applying a voltage to the piezoelectric element, connected between the driving means and the piezoelectric element, and when the voltage is applied by the driving means, a current limiting resistor that limits the current supplied to the piezoelectric element, based on changes in the difference between the input voltage and the output voltage generated at both ends of the current limiting resistor by a voltage applied to the piezoelectric element, the vibration And detecting means for detecting a failure of the apparatus.

The vibration device according to the present invention is a vibration device, which is connected between a piezoelectric element, a driving means for applying a voltage to the piezoelectric element, and the driving means and the piezoelectric element. A current limiting resistor for limiting a current supplied to the piezoelectric element when a voltage is applied by the driving means; and an input voltage and an output voltage generated across the current limiting resistor by the voltage applied to the piezoelectric element. Detecting means for detecting a failure of the vibration exciter on the basis of a change in the difference between the excitation device and the vibration device.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to perform the failure detection of the vibration apparatus using a piezoelectric element easily with a simple structure.

  Hereinafter, a single-lens reflex digital camera equipped with an excitation device using a piezoelectric element according to an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram of a single-lens reflex digital camera according to an embodiment of the present invention.

  In FIG. 1, reference numeral 110 denotes a replaceable photographing lens unit for forming a subject image, 111 denotes a stop provided in the photographing lens unit 110 for adjusting the amount of light incident on the image sensor 120, and 120 denotes a subject image. It is an image sensor for photoelectrically converting. An optical member 120a such as a low-pass filter or a cover filter is disposed close to the front surface of the image sensor 120, and foreign matter adheres to the surface of the optical member 120a. The adhered foreign matter is reflected in the subject image on the image sensor 120 as a shadow. Around the optical member 120a, there is disposed a piezoelectric element 120b that vibrates the optical member 120a and removes foreign matter adhering thereto. A piezoelectric element driving unit 122 for driving the piezoelectric element 120b is connected to the piezoelectric element 120b.

  Reference numeral 132 denotes an A / D converter that converts an analog image signal output from the image sensor 120 into a digital signal. Reference numeral 140 denotes an image processing apparatus that processes the digital image signal output from the A / D converter. Reference numeral 133 denotes a lens system controller that controls the lens position and aperture of the photographing lens unit 110, and 121 denotes various sensors such as an AF (autofocus) sensor and an AE (automatic exposure) sensor. Further, 130 is a camera control unit that controls the operation of the entire digital camera, 150 is an I / O with a shutter button, a display, a shooting mode selection dial, and the like, and 134 is a memory that stores captured images and various information.

  User operations are acquired via the I / O 150, and power ON / OFF, shooting operations, and the like are performed according to user operations. When a shooting operation is instructed, the camera control unit 130 determines appropriate shooting conditions based on information obtained from the various sensors 121 and the image sensor 120, and sets an appropriate lens position and the like via the lens system control unit 133. To do. After the exposure, the output signal of the image sensor 120 is digitized via the A / D converter 132 and then subjected to appropriate image processing by the image processing device 140 and stored in the memory 134. If necessary, an image is displayed on a display (not shown) via the I / O 150.

  The image processing apparatus 140 performs processing such as white balance adjustment, RGB development, and compression encoding.

  FIG. 2 is a diagram illustrating an appearance of a single-lens reflex digital camera according to an embodiment. Specifically, FIG. 2 is a perspective view seen from the front side of the camera, and shows a state in which the taking lens unit is removed.

  In FIG. 2, reference numeral 1 denotes a camera body, which is provided with a grip portion 1a that protrudes forward so that a user can easily hold the camera stably during shooting. Reference numeral 202 denotes a mount unit that fixes a detachable taking lens unit 110 (see FIG. 1) to the camera body. The mount contact 221 has a function of exchanging control signals, status signals, data signals, and the like between the camera body 1 and the photographing lens unit 110 and supplying power to the photographing lens unit. Further, the mount contact 221 may be configured to be capable of not only electrical communication but also optical communication and voice communication.

  Reference numeral 204 denotes a lens lock release button that is pushed in when the photographing lens unit 110 is removed. Reference numeral 205 denotes a mirror box disposed in the camera casing, and the photographic light flux that has passed through the photographic lens is guided here. A quick return mirror 206 is disposed inside the mirror box 205. The quick return mirror 206 is held at a 45 ° angle with respect to the photographic optical axis in order to guide the photographic light flux in the direction of the pentaprism (not shown), and in the direction of the image sensor 120 (see FIG. 1). In order to guide, it can be in a state of being held at a position retracted from the photographing light flux.

  On the grip side of the upper part of the camera, a shutter button 207 as a start switch for starting shooting, a main operation dial 208 for setting a shutter speed and a lens aperture value according to an operation mode at the time of shooting, and an operation mode of the shooting system A setting button 210 is arranged. Some of the operation results of these operation members are displayed on the LCD display panel 209. The I / O 150 shown in FIG. 1 is mainly an I / O with these operation members, a display panel, and the like.

  The shutter button 207 is configured such that the switch SW1 is turned on by a first stroke (half press) and the switch SW2 is turned on by a second stroke (full press).

  The operation mode setting button 210 is used to set whether the continuous shooting or only one frame shooting is performed when the shutter button 207 is pressed once, the self shooting mode setting, and the like. The setting status is displayed at 209.

  A flash unit 211 that pops up with respect to the camera body, a flash mounting shoe groove 212, and a flash contact 213 are arranged at the upper center of the camera, and a shooting mode setting dial 214 is arranged at the upper right of the camera. Note that the shooting mode setting dial 214 also serves as an activation operation unit that operates to vibrate the optical member 120a with the piezoelectric element 120b and remove foreign matters such as dust attached to the surface of the optical member 120a.

  An external terminal lid 215 that can be opened and closed is provided on the side opposite to the grip side. Inside the external terminal lid 215, a video signal output jack 216 and a USB output connector are provided as external interfaces. 217 is stored.

  Next, FIG. 3 is a block diagram showing a configuration of the vibration device 150 including the piezoelectric element 120b and the piezoelectric element driving unit 122 in the present embodiment.

  In FIG. 3, the vibration device 150 includes a piezoelectric element 120b and a piezoelectric element driving unit 122 that drives the piezoelectric element 120b. The piezoelectric element driving unit 122 includes a driving circuit 5 for applying a predetermined voltage to the piezoelectric element 120b, and a current limiting resistor 3 for limiting a charging current to the piezoelectric element 120b having a capacitance. Further, a failure detection signal generation circuit 4 that generates a failure detection signal indicating whether or not the vibration exciter 150 has failed based on the voltages at both ends 3a and 3b of the current limiting resistor 3 is also provided.

  The piezoelectric element 120b is a drive source in the vibration device 150, and expands and contracts according to the voltage applied from the drive circuit 5, and vibrates the optical member 120a described above. The piezoelectric element 120 b is detachably connected to the piezoelectric element driving unit 122 by the connection harness 2. When there is a connection failure in the connection harness 2, no voltage is applied to the piezoelectric element 120b, resulting in an open mode failure.

  The drive circuit 5 is a circuit that supplies a voltage to be applied to the piezoelectric element 120b. The drive circuit 5 includes a power supply circuit unit that generates a voltage to be applied to the piezoelectric element 120b, and a switching circuit unit that switches the voltage supply of the power supply circuit unit in accordance with a control pattern from the camera control unit 130.

  The current limiting resistor 3 is a resistor for suppressing the maximum inrush current of the drive circuit 5. In the present embodiment, the failure detection signal generation circuit 4 generates a failure detection signal using the resistance constant of the current limiting resistor 3 and the pulse delay due to the capacitance of the piezoelectric element 120b. The principle that the failure detection signal generation circuit 4 generates a failure detection signal will be described later.

  The camera control unit 130 includes a CPU, a timer circuit, an interrupt control circuit, a pulse generation circuit, a general-purpose IO port, a display circuit, a memory, and the like. When the piezoelectric element 120b is driven, the camera control unit 130 always determines the state of the failure detection signal output from the failure detection signal generation circuit 4, and performs stop processing of the piezoelectric element 120b when an abnormality is detected. In FIG. 3, the piezoelectric element driving unit 122 and the camera control unit 130 are connected by three signal lines, but are omitted from FIG. 1 and shown by one signal line.

  FIG. 4 is a detailed circuit diagram of the failure detection signal generation circuit 4 in the present embodiment. FIG. 5 is a waveform diagram of main signals of the failure detection signal generation circuit 4 in the present embodiment.

  In FIG. 4, the failure detection signal generation circuit 4 includes an NPN transistor 7, a diode 9, and peripheral resistors 8, 10, 11, and 12. The resistor 8 and the diode 9 are connected from the emitter terminal to the base terminal of the NPN transistor 7, and are a protection circuit for preventing a voltage higher than the breakdown voltage from being applied between the emitter and the base. The resistors 10 and 11 are for setting the bias voltage of the base terminal of the NPN transistor 7. Further, the resistor 12 is a pull-up resistor connected to the collector terminal of the NPN transistor 7 and the power supply voltage Va of the drive circuit 5.

  The drive signal (1) and the drive signal (2) shown in FIGS. 4 and 5 are signals applied to both ends of the piezoelectric element 120b by the drive circuit 5, and the voltages of the drive signal (1) and the drive signal (2). Depending on the state, the piezoelectric element 120b stops or vibrates.

  As shown in FIG. 5, the drive signal (1) and the drive signal (2) are both at the voltage Vs when the piezoelectric element 120b is stationary. Then, immediately after the driving of the piezoelectric element 120b is started, the driving signal (1) changes from the voltage Vs to a predetermined voltage Va (Va> Vs). At this time, the drive signal (2) remains at the voltage Vs.

  Thereafter, after a period of WIDTH_H_TIME, which is about ½ of the vibration period of the piezoelectric element 120b, the drive signal (1) changes simultaneously from the voltage Va to the voltage Vs, and the drive signal (2) changes simultaneously from the voltage Vs to the voltage Va. To do. Next, after the lapse of the WIDTH_L_TIME period, which is also about 1/2 of the vibration period of the piezoelectric element 120b, the drive signal (1) changes from the voltage Vs to the voltage Va, and the drive signal (2) changes from the voltage Va to the voltage Vs. Change at the same time. Thus, by alternately inverting the drive signal (1) and the drive signal (2) input to the piezoelectric element 120b, a voltage of ± Va is applied to both ends of the piezoelectric element 120b. Thereby, the piezoelectric element 120b can be vibrated.

  Note that the drive capability of the piezoelectric element 120b can be changed by changing the drive pulse period (WIDTH_H_TIME / WIDTH_L_TIME) instructed by the camera control unit 130 or changing the value of the applied voltage Va of the drive circuit 5. Is possible.

  The failure detection signals shown in FIGS. 4 and 5 are input to a general-purpose port capable of interrupt control of the camera control unit 130.

  Next, the principle by which the failure detection signal generation circuit 4 generates a failure detection signal will be described with reference to FIGS.

  Here, the description will be given focusing on the drive signal (1) in FIG. 5 applied to the piezoelectric element 120b.

  First, when the drive circuit 5 changes the applied voltage from the voltage Vs applied when the piezoelectric element 120b is stationary at time t = 0 to the applied voltage Va for obtaining a desired displacement, the current limiting resistor 3 Thus, charging of the piezoelectric element 120b having capacitance is started. Immediately after application of the voltage Va, the voltage Vap at one end 3a of the current limiting resistor 3 is Va, and the voltage Vbp at the other end 3b is Vs, so that both ends 3a, 3b of the current limiting resistor 3 are (Vap A voltage difference of −Vbp) = (Va−Vs) is generated. However, after a predetermined time has elapsed from the start of charging of the piezoelectric element 120b, the voltage Vbp of the piezoelectric element 120b (the other end 3b of the current limiting resistor 3) gradually becomes the voltage Vap (= Va) of the one end 3a of the current limiting resistor 3. It approaches and eventually becomes equal to Va. During a period ERR_LIMIT_TIME until the voltage difference between both ends 3 a and 3 b of the current limiting resistor 3 disappears, the failure detection signal generation circuit 4 outputs a failure detection signal to the camera control unit 130.

  This will be described in more detail.

  In the normal operation of FIG. 5A, when the voltage of the drive signal (1) is changed from the static voltage Vs to the voltage Va corresponding to the desired displacement as shown in FIG. 5A. The voltage Vap at the end 3a on the drive circuit 5 side of the current limiting resistor 3 immediately changes to Va. However, the voltage Vbp at the end 3b of the current limiting resistor 3 on the piezoelectric element 120b side is shown in the upper diagram of FIG. 5B due to the pulse response characteristics of the capacitance of the piezoelectric element 120b and the resistance value of the current limiting resistor 3. Delay as shown. At this time, the end 3 a of the current limiting resistor 3 is connected to the base terminal of the NPN transistor 7 via the resistor 10, and the end 3 b of the current limiting resistor 3 is connected to the emitter terminal of the NPN transistor 7. ing. Therefore, the voltage difference (Vap−Vbp) between the two end portions 3a and 3b caused by the delay due to the pulse response characteristic is applied to the NPN transistor 7 as the base-emitter voltage difference Vbe. A voltage that is a constant multiple of the base-emitter voltage difference Vbe is output from the collector of the NPN transistor 7, and this output becomes a failure detection signal. Therefore, the failure detection signal is shown in the lower waveform of FIG. 5B during the period ERR_LIMIT_TIME, which is the time until the voltage Vbp shown in the upper waveform of FIG. 5B reaches Va. Change. That is, it changes so that it once becomes Lo level and returns to Hi level again.

  As a result, when there is no failure in the vibration exciter 150, the failure detection signal changes from Hi to Lo and changes to Hi again during the period of ERR_LIMIT_TIME.

  On the other hand, when the open mode failure shown in FIG. 5B occurs, the voltage of the drive signal (1) corresponds to the desired displacement from the voltage Vs in the stationary state as shown in FIG. 5A. When the voltage changes to Va, the voltages at both ends 3a and 3b of the current limiting resistor 3 are as follows. That is, the voltage at the end 3b on the piezoelectric element 120b side of the current limiting resistor 3 does not cause a delay in voltage increase because the capacitance of the piezoelectric element 120b does not exist, and is shown in the upper diagram of FIG. It becomes Va immediately. Therefore, the base-emitter voltage difference Vbe of the NPN transistor 7 is almost zero, and the transistor 7 is always in the switch OFF state. Therefore, the failure detection signal remains at the Hi level as shown in the lower diagram of FIG. 5C, and remains at the Hi level during the period of ERR_LIMIT_TIME.

  In addition, when the short-circuit mode failure shown in FIG. 5C occurs, the voltage of the drive signal (1) corresponds to the desired displacement from the voltage Vs in the stationary state as shown in FIG. 5A. When the voltage changes to Va, the voltages at both ends 3a and 3b of the current limiting resistor 3 are as follows. That is, the voltage at the end portion 3b of the current limiting resistor 3 on the piezoelectric element 120b side is short-circuited between the drive signal (1) and the drive signal (2), and as shown in the upper diagram of FIG. It remains almost at Vs. At this time, the base-emitter voltage difference Vbe of the NPN transistor 7 is substantially (Va−Vs), and the transistor 7 is always in the switch ON state as shown in the lower diagram of FIG. Therefore, the failure detection signal remains at the Lo level, and remains at the Lo level during the above ERR_LIMIT_TIME period.

  As described above, the camera control unit 130 can detect the failure of the vibration generator 150 according to the state of the failure detection signal during the ERR_LIMIT_TIME period.

  In the present embodiment, the voltage application switching method to the piezoelectric element 120b of the drive circuit 5 has been described as the full bridge switch drive method, but may be a half bridge switch drive method.

  In the present embodiment, the transistor 7 is described as an NPN type, but a PNP type transistor may be used.

  FIG. 6 is a flowchart showing drive control of the vibration device 150 in the present embodiment.

  In step S1, the camera control unit 130 clears the counter [COUNT] of the internal timer. Also, an H level width [WIDTH_H_TIME], an L level width [WIDHT_L_TIME], and a failure detection signal detection limit time [ERR_LIMIT_TIME] of the drive signal of the piezoelectric element 120b are set.

  In step S2, the failure detection signal detection flag [ERR_DET_FLAG] is cleared.

  In step S3, an internal timer counter is started.

  In step S4, the camera control unit 130 sends a control signal to the drive circuit 5 to apply a voltage to the piezoelectric element 120b, and changes the drive signal (1) to the voltage Va and the drive signal (2) to the voltage Vs. . At this time, the failure detection signal generation circuit 4 inputs a failure detection signal corresponding to the failure state of the vibration exciter 150 to the camera control unit 130. Specifically, as already described, when the vibration device 150 is not broken, a failure detection signal that changes from Hi → Lo → Hi is input, and in the case of an open mode failure, it remains Hi. In the case of a short-circuit mode failure, a signal that remains Lo is input.

  In step S5, the camera control unit 130 detects an edge point where the failure detection signal changes from Lo level to Hi level. If an edge point is detected, the process proceeds to step S6. Proceed to S7.

  In step S6, the camera control unit 130 sets the detection flag [ERR_DET_FLAG] to H.

  Next, the camera control unit 130 detects whether or not the detection flag [ERR_DET_FLAG] is set to H in step S7. If it is set, the process proceeds to step S8, and if it is not set, Proceed to step S12.

  In step S12, it is determined whether internal timer counter [COUNT]> detection limit time [ERR_LIMIT_TIME]. If the internal timer counter does not exceed the detection limit time, the process returns to step S5.

  Here, when the vibration device 150 has not failed, an edge point where the failure detection signal changes from Lo to Hi is always detected within the ERR_LIMIT_TIME period. Therefore, in step 7, the detection flag [ERR_DET_FLAG] is set to H. The process proceeds to step 8.

  However, when the vibration exciter 150 is in a failure state, the edge point at which the failure detection signal changes from Lo to Hi is not detected, so the detection flag [ERR_DET_FLAG] does not become H. Then, the detection flag [ERR_DET_FLAG] does not become H, the internal timer counter [COUNT] exceeds the detection limit time [ERR_LIMIT_TIME], and the process proceeds to Step 13 and the subsequent steps.

  In step S8, the camera control unit 130 waits until the period [WIDTH_H_TIME] in which the count [COUNT] of the internal timer is at the H level of the drive signal (1) of the piezoelectric element 120b ends. When the H level period ends, this time, in order to apply the inverted voltage to the piezoelectric element 120b, a control signal is sent to the drive circuit 5, the drive signal (1) is changed to the voltage Vs, and the drive signal (2) is changed to the voltage. Change to Va (step S9).

  In step S10, the camera control unit 130 waits until the period [WIDTH_L_TIME] in which the count [COUNT] of the internal timer is at the L level of the drive signal (1) of the piezoelectric element 120b ends. When the L level period ends, the process proceeds to step S11.

  In step S11, when the operation of the vibration generator 150 is continued, the process returns to step 1 to shift to the next drive control. If it is determined in step 11 that the final drive signal has been sent, the drive control of the vibration generator 150 is terminated.

  If a failure of the vibration exciter 150 is detected, it is determined from the failure detection signal in step S13 whether the failure is an open mode failure or a short-circuit mode failure. Specifically, when the failure detection signal is at the H level, it is determined that the failure is in the open mode, and when it is at the L level, it is determined that the failure is in the short-circuit mode.

  In step S14, the camera control unit 130 changes both the drive signal (1) and the drive signal (2) to the voltage Vs in order to stop energization of the piezoelectric element 120b. At the same time, the camera control unit 130 issues a warning to notify the failure state.

  In the description of the present embodiment, the case where the piezoelectric element is driven only with a single voltage Va is described. However, the present invention can be applied to a case where the voltage is changed to a plurality of voltages (Va ′, Va ″,...), For example. Applicable.

  Further, in the description of the present embodiment, it has been described that a failure is detected when the voltage is changed from Vs which is a low voltage to Va which is a high voltage. However, by using two transistors 7 and inputting each failure detection signal to the camera control unit 130, it is also possible to detect a failure when changing from a high voltage Va to a low voltage Vs. is there.

(Other embodiments)
The object of each embodiment is also achieved by the following method. That is, a storage medium (or recording medium) in which a program code of software that realizes the functions of the above-described embodiments is recorded is supplied to the system or apparatus. Then, the computer (or CPU or MPU) of the system or apparatus reads and executes the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but the present invention includes the following cases. That is, based on the instruction of the program code, an operating system (OS) running on the computer performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

  Furthermore, the following cases are also included in the present invention. That is, the program code read from the storage medium is written in a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer. Thereafter, based on the instruction of the program code, the CPU or the like provided in the function expansion card or function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

  When the present invention is applied to the above storage medium, the storage medium stores program codes corresponding to the procedure described above.

1 is a block diagram of a single-lens reflex digital camera according to an embodiment of the present invention. It is a figure which shows the external appearance of the single-lens reflex digital camera of one Embodiment. It is a block diagram which shows the structure of the vibration apparatus containing a piezoelectric element and a piezoelectric element drive part in one Embodiment. It is a detailed circuit diagram of the failure detection signal generation circuit in one embodiment. It is a wave form diagram of the main signal of the failure detection signal generation circuit in one embodiment. It is a flowchart which shows the drive control of the vibration excitation apparatus in one Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Camera body 2 Connection harness 3 Current limiting resistance 4 Fault detection signal generation circuit 5 Drive circuit 7 Transistor 8 Resistance 9 Diode 10, 11 Resistance 12 Resistance (for pull-up)

Claims (10)

An image sensor that photoelectrically converts a subject image;
An optical element disposed in front of the imaging element;
An excitation device including a piezoelectric element that vibrates the optical element;
Driving means for applying a voltage to the piezoelectric element;
A current limiting resistor connected between the driving means and the piezoelectric element and limiting a current supplied to the piezoelectric element when a voltage is applied by the driving means;
Detecting means for detecting a failure of the vibration exciter based on a change in a difference between an input voltage and an output voltage generated at both ends of the current limiting resistor by a voltage applied to the piezoelectric element;
An imaging apparatus comprising:   The detection means includes a transistor, and the detection means is based on an output signal from a collector when a voltage generated at both ends of the current limiting resistor is applied between a base and an emitter of the transistor. The imaging apparatus according to claim 1, wherein a failure of the imaging device is detected. The detecting means detects that the vibration exciter is free from failure when the magnitude of the difference between the input voltage and the output voltage reaches a predetermined magnitude within a predetermined period. The imaging apparatus according to claim 1 or 2. The imaging apparatus according to claim 3, wherein the predetermined period is a period until an output voltage of the current limiting resistor becomes equal to a voltage applied by the driving unit. The detecting means detects a failure pattern of the vibration exciter based on a difference between the input voltage and the output voltage when a predetermined change does not appear in the difference between the input voltage and the output voltage. The imaging apparatus according to any one of claims 1 to 4, wherein A vibration exciter,
A piezoelectric element;
Driving means for applying a voltage to the piezoelectric element;
A current limiting resistor connected between the driving means and the piezoelectric element and limiting a current supplied to the piezoelectric element when a voltage is applied by the driving means;
Detecting means for detecting a failure of the vibration exciter based on a change in a difference between an input voltage and an output voltage generated at both ends of the current limiting resistor by a voltage applied to the piezoelectric element;
A vibration apparatus comprising: The detection means includes a transistor, and the detection means is based on an output signal from a collector when a voltage generated at both ends of the current limiting resistor is applied between a base and an emitter of the transistor. The vibration device according to claim 6 , wherein a failure is detected. The detecting means detects that the vibration exciter is free from failure when the magnitude of the difference between the input voltage and the output voltage reaches a predetermined magnitude within a predetermined period. The vibration device according to claim 6 or 7. 9. The vibration exciter according to claim 8, wherein the predetermined period is a period until an output voltage of the current limiting resistor becomes equal to a magnitude of a voltage applied by the driving unit. The detecting means detects a failure pattern of the vibration exciter based on a difference between the input voltage and the output voltage when a predetermined change does not appear in the difference between the input voltage and the output voltage. The vibration device according to any one of claims 6 to 9, characterized by:

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