JP2008003165A - Imaging device, its control method, program, and storage medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively remove foreign matters sticking onto the surface of an optical element etc., arranged in front of an imaging element. <P>SOLUTION: The imaging device includes: the imaging element 120 that performs the photoelectric conversion of an object image; the optical member 120a arranged in front of the imaging element; vibrating parts 120b and 122 for vibrating the optical member; and a control part 130 that controls the vibrating parts so that the optical member may be vibrated in a first frequency band including a first resonance frequency where the vibration acceleration of the optical member in vibrating becomes the maximum, thereafter, the optical member may be vibrated in a second frequency band including a second resonance frequency different from the first resonance frequency of the optical member and not continuing the first frequency band. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for removing foreign matter attached to the surface of an optical member disposed in the vicinity of an imaging surface such as an optical filter in an imaging apparatus such as a digital camera provided with a solid-state imaging device.

  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 foreign matter such as dust adheres to the optical element, the foreign matter is reflected in the image and the quality of the image 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, for example, Patent Document 1).
JP 2003-333391 A

  However, the technique described in Patent Document 1 has a problem that a sufficient dust removal effect cannot be obtained because resonance does not necessarily occur due to individual differences in the resonance frequency of the optical element for each camera. There is also a problem that it takes time and effort to measure the resonance frequency in advance for each individual and store it in the EEPROM.

  Accordingly, the present invention has been made in view of the above-described problems, and an object of the present invention is to enable effective removal of foreign matters attached to the surface of an optical element or the like disposed in front of an imaging element. .

  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 photoelectrically converts a subject image, an optical member that is disposed in front of the imaging element, and the optical member that vibrates. And vibration means for causing the optical member to vibrate in a first frequency band including a first resonance frequency that maximizes vibration acceleration when the optical member vibrates. Control means for controlling the excitation means so as to vibrate in a second frequency band that includes a second resonance frequency different from the first resonance frequency and is not continuous with the first frequency band. It is characterized by doing.

  According to another aspect of the present invention, there is provided a method for controlling an imaging apparatus comprising: an imaging element that photoelectrically converts a subject image; an optical member disposed in front of the imaging element; and an excitation unit that vibrates the optical member. A method of controlling an imaging apparatus comprising: oscillating the optical member in a first frequency band including a first resonance frequency that maximizes vibration acceleration during vibration of the optical member; And a step of controlling the excitation means so as to vibrate in a second frequency band that includes a second resonance frequency different from the first resonance frequency of the member and is not continuous with the first frequency band. It is characterized by doing.

  A program according to the present invention causes a computer to execute the above control method.

  A storage medium according to the present invention stores the above program.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to remove effectively the foreign material adhering to surfaces, such as an optical element arrange | positioned ahead of an image pick-up element.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a block diagram of a digital single-lens reflex 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 digital single-lens reflex 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 2 denotes a mount, which fixes a detachable taking lens unit 110 (see FIG. 1) to the camera body. The mount contact 21 exchanges control signals, status signals, data signals, and the like between the camera body 1 and the photographing lens unit 110 and has a function of supplying power to the photographing lens unit. Further, the mount contact 21 may be configured not only for electrical communication but also for optical communication, voice communication, and the like.

  Reference numeral 4 denotes a lens lock release button that is pushed in when the photographing lens unit 110 is removed. Reference numeral 5 denotes a mirror box disposed in the camera housing, and the photographic light flux that has passed through the photographic lens is guided here. A quick return mirror 6 is disposed inside the mirror box 5. The quick return mirror 6 is held at an angle of 45 ° with respect to the photographing optical axis in order to guide the photographing 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, it can be held in a position retracted from the photographing light flux.

  On the grip side of the upper part of the camera, a shutter button 7 as a start switch for starting shooting, a main operation dial 8 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 10 is arranged. Some of the operation results of these operation members are displayed on the LCD display panel 9. 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 7 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 10 is used to set whether the continuous shooting or only one frame shooting is performed when the shutter button 7 is pressed once, the self shooting mode setting, and the like. 9 shows the setting status.

  A flash unit 11 that pops up with respect to the camera body, a shoe groove 12 for attaching a flash, and a flash contact 13 are arranged at the upper center of the camera, and a shooting mode setting dial 14 is arranged at the upper right of the camera. Note that the shooting mode setting dial 14 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 15 that can be opened and closed is provided on the side opposite to the grip side. Inside the external terminal lid 15, a video signal output jack 16 and a USB output connector are provided as external interfaces. 17 is stored.

  FIG. 3 is a diagram showing the relationship between the vibration frequency and the amplitude of the optical member 120a excited by the piezoelectric element 120b shown in FIG.

  In FIG. 3, the X axis is the vibration frequency, and the Y axis is the vibration amplitude. F1 is a first frequency band including the first resonance frequency f1 of the optical member 120a, and F2 is a second frequency band including the second resonance frequency f2 of the optical member 120a. The vibration acceleration is proportional to the product of the square of the vibration frequency and the amplitude, but the vibration acceleration at the first resonance frequency f1 is larger than the vibration acceleration at the second resonance frequency f2, and the maximum vibration acceleration of the optical member 120a is It has become.

  Next, FIG. 4 is a flowchart showing an operation of driving the piezoelectric element 120b to remove foreign matters such as dust from the surface of the optical member 120a. Hereinafter, the foreign matter removing operation will be described with reference to FIGS.

  When the shooting mode setting dial 14 is operated, the camera control unit 130 detects this and activates the camera body 1. In addition, the camera control unit 130 instructs the piezoelectric element driving unit 122 to apply a periodic voltage to the piezoelectric element 120b, and excites vibration of the optical member 120a (step S1).

  This first vibration starts from a frequency f1a at one end of the first frequency band F1 including the first resonance frequency f1 at which the vibration acceleration proportional to the product of the square of the vibration frequency and the amplitude is maximized (step S2). .

  Thereafter, if the operation member of the camera body 1 related to photographing is not operated (step S3, NO), the frequency gradually increases from the first resonance frequency f1 to the frequency f1b at the preset first frequency change pitch P1. To change.

  When this vibration ends (step S4, YES), the vibration of the frequency f2a at one end of the second frequency band F2 including the second resonance frequency f2 is started (step S5).

  After that, if the operation member of the camera body 1 related to photographing is not operated (step S6, NO), the frequency gradually increases at the preset second frequency change pitch P2 from the second resonance frequency f2 to the frequency f2b. To change.

  When this vibration is finished (step S7, YES), the camera control unit 130 commands the piezoelectric element driving unit 122 to stop the voltage application to the piezoelectric element 120b, and the vibration of the optical member 120a is stopped (step S8). The main body 1 enters a normal shooting standby state (step S9). The above is the normal foreign matter removing operation.

  Next, a description will be given of a case where an operation of the operation member of the camera body 1, such as the shutter button 7, related to photographing is detected after the start of vibration in the first frequency band F1 (steps S1 and S2) (YES in step S3).

  The camera body 1 gives priority to the user's intention to interrupt the vibration of the piezoelectric element 120b (step S10), and operates the photographing lens unit 110, the image sensor 120, the image processing device 140, etc. to perform a photographing operation according to the photographing operation. Is performed (step S11).

  Thereafter, when the photographing operation is completed or the user interrupts the photographing (step S12), the process returns to step S2. That is, since the vibration in the first frequency band F1 is not completed as described above, the restart of the foreign substance removal operation is the vibration of the frequency f1a at one end of the first frequency band F1 including the first resonance frequency f1. (Step S2).

  Next, a description will be given of a case where an operation of an operation member of the camera body 1, such as the shutter button 7, related to shooting is detected after the start of vibration in the second frequency band F2 (step S5) (YES in step S6).

  The camera body 1 gives priority to the user's intention to interrupt the vibration of the piezoelectric element 120b (step S13), and operates the photographing lens unit 110, the image sensor 120, the image processing device 140, etc. to perform a photographing operation according to the photographing operation. Is performed (step S14).

  Thereafter, when the photographing operation is completed or the user interrupts photographing (step S15), the process returns to step S5. That is, since the vibration in the second frequency band F2 is not completed as described above, the restart of the foreign substance removal operation is the vibration of the frequency f2a at one end of the second frequency band F2 including the second resonance frequency f2. (Step S5).

  As described above, in this embodiment, the vibration frequency of the foreign substance removal operation changes from f1a to f1b in the first frequency band F1, and further changes from f2a to f2b in the second frequency band F2. Therefore, if the approximate width in which each resonance frequency of the optical member 120a exists is known in advance, the resonance can be surely generated even if there is an influence due to an individual difference for each camera or a temperature change.

  Furthermore, in this embodiment, the vibration waveform in the first frequency band F1 including the first resonance frequency f1 at which the vibration acceleration is maximum is the vibration in the second frequency band F2 including the second resonance frequency f2. It is steeper than the waveform. Correspondingly, the first frequency change pitch P1 in the first frequency band F1 is set smaller than the second frequency change pitch P2 in the second frequency band. This is because if the first frequency change pitch P1 is set larger than the steep first resonance frequency f1, the first resonance frequency f1 is skipped during the change of the vibration frequency, and the resonance This is because there is a possibility that a sufficient foreign matter removing effect may not be obtained without occurring. In the present embodiment, the first frequency change pitch P1 is set small with respect to the vicinity of the first resonance frequency f1 where the vibration waveform is steep. Therefore, the possibility of skipping the first resonance frequency f1 in the middle of the frequency change is low, and it is possible to obtain a sufficient foreign matter removing effect by reliably causing resonance.

  Further, the foreign matter removal effect is most effective when the acceleration applied to the foreign matter is maximum. In the present embodiment, the first vibration of the foreign matter removal operation is the first resonance frequency f1 at which the vibration acceleration is maximized. Starts from the frequency f1a at one end of the first frequency band F1 including That is, the maximum foreign matter removal effect is obtained during vibration in the first first frequency band. Accordingly, even if the foreign object removal operation is interrupted when, for example, the operation of the shutter button 7 is detected during the vibration, the decrease in the foreign substance removal effect can be minimized.

  In the above description, the foreign matter removal operation is started by turning on the power to the camera body 1 by operating the photographing mode setting dial 14, but a foreign matter removal activation button may be provided separately, for example. Further, it may be after the end of shooting with long exposure.

  Further, the case where the vibration waveform near the first resonance frequency f1 having a high foreign matter removal effect is steep has been described, but conversely, the vibration waveform near the first resonance frequency f1 is a gentler waveform. Needless to say, the present invention is applicable.

  Here, an example of a specific configuration in which the optical element 120a is vibrated by the piezoelectric element 120b will be described.

  FIG. 5 is an exploded perspective view for explaining components constituting the unit of the imaging unit 400 including the imaging element 120, the optical member 120a, and the piezoelectric element 120b.

  Reference numeral 500 denotes an image sensor unit, which includes at least an image sensor 120 and an image sensor holding member 510. An optical element unit 470 includes at least the optical element 120a, the optical element holding member 420, the piezoelectric element 120b, the biasing member 440, the elastic member 450, and the regulating member 460.

  The restriction member 460 sandwiches the optical element 120a with the optical element holding member 420 at a predetermined interval in the photographing optical axis direction, thereby restricting the movement of the optical element 120a in the photographing optical axis direction. Yes. By restricting in this way, the optical element 120a is prevented from tilting more than a predetermined angle with respect to a plane orthogonal to the photographing optical axis.

The restricting member 460 has an opening that restricts the opening of the optical element 120a, and shields a photographing light beam incident on the portion other than the opening. Thereby, the photographing light flux is prevented from entering the image pickup device from the outer peripheral portion of the optical element 120a, and the ghost caused by the reflected light is prevented.

  Reference numeral 520 denotes a rubber sheet having elasticity. The rubber sheet 520 is sandwiched via the arm portion 420b of the optical element holding member 420 and is locked to the image pickup element holding member 510 by the step screw 530, whereby the optical element unit 470 is locked to the image pickup element unit 500. The

  With this configuration, the optical element 120a can be vibrated by the piezoelectric element 120b. Needless to say, the vibration of the optical element 120a is not limited to this configuration, and can be realized by various methods.

  As described above, according to the above-described embodiment, since the vibration frequency is wide, even if there is an individual difference in the resonance frequency of the optical member to which foreign matter has adhered, it is possible to reliably generate resonance. .

  In addition, since an appropriate frequency change pitch is set according to the vibration waveform in the vibration frequency band, the possibility of skipping the resonance frequency is low when the vibration waveform near the resonance frequency is steep. Resonance is reliably generated and a high foreign matter removing effect can be obtained. In addition, when the vibration waveform near the resonance frequency is gentle, the time required for vibration can be shortened.

  In addition, since the vibration is started from a frequency band including the frequency at which the vibration acceleration is maximum, even if the foreign matter removal operation is interrupted for photographing, a reduction in the foreign matter removal effect can be minimized.

(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) or the like 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 into 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, a 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.

It is a block diagram of the digital single-lens reflex camera concerning one Embodiment of this invention. It is a figure which shows the external appearance of the digital single-lens reflex camera of one Embodiment. It is a figure which shows the relationship between the vibration frequency and amplitude of the optical member vibrated by the piezoelectric element shown in FIG. It is a flowchart which shows the operation | movement which drives a piezoelectric element and removes foreign materials, such as dust, from the surface of an optical member. It is explanatory drawing of the drive mechanism of the optical element 102a which is common in 1st Embodiment and 2nd Embodiment.

Explanation of symbols

1 Camera body 2 Mount 5 Mirror box 6 Quick return mirror 7 Shutter button 14 Shooting mode setting dial

Claims (9)

An image sensor that photoelectrically converts a subject image;
An optical member disposed in front of the image sensor;
Vibration means for vibrating the optical member;
The optical member is vibrated in a first frequency band including a first resonance frequency at which vibration acceleration at the time of vibration of the optical member is maximized, and thereafter, the optical member is different from the first resonance frequency of the optical member. Control means for controlling the excitation means so as to vibrate in a second frequency band that includes two resonance frequencies and is not continuous with the first frequency band;
An imaging apparatus comprising:   The control means vibrates the optical member while gradually changing the frequency at the first frequency change pitch in the first frequency band, and gradually increases the frequency at the second frequency change pitch in the second frequency band. The imaging apparatus according to claim 1, wherein the excitation unit is controlled so as to vibrate the optical member while being changed.   The control means is configured such that the first and second frequency change pitches are small and gradual when the ratio of the change in amplitude to the frequency change near the first and second resonance frequencies is steep. The imaging apparatus according to claim 2, wherein the imaging apparatus is set to a large value.   The image pickup apparatus according to claim 1, wherein the control unit stops the vibration operation of the vibration unit when a photographing operation is performed on the image pickup apparatus.   The control means restarts the vibration operation of the vibration means when the photographing operation of the imaging apparatus is finished or interrupted after stopping the vibration operation of the vibration means. The imaging device according to claim 4.   The imaging apparatus according to claim 5, wherein the control unit restarts the excitation operation of the excitation unit from a frequency band at the time when the operation of the excitation unit is stopped. A method of controlling an imaging device comprising: an imaging device that photoelectrically converts a subject image; an optical member disposed in front of the imaging device; and a vibration means for vibrating the optical member,
The optical member is vibrated in a first frequency band including a first resonance frequency at which vibration acceleration at the time of vibration of the optical member is maximized, and thereafter, the optical member is different from the first resonance frequency of the optical member. 2. A method for controlling an imaging apparatus, comprising: a step of controlling the excitation means so as to vibrate in a second frequency band that includes two resonance frequencies and is not continuous with the first frequency band .   A program for causing a computer to execute the control method according to claim 7.   A computer-readable storage medium storing the program according to claim 8.

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