JP2005331653A - Electrostatic shutter mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic shutter mechanism in which thickness reduction is achieved by preventing a plurality of shutter curtain drive mechanisms from mutually interfering. <P>SOLUTION: The electrostatic shutter mechanism includes: a first fixed member 1b having a first driving electrode (4b) and an opening on its surface; a first moving member (24b) with light shield properties movable relative to the first fixed member by receiving drive force produced by the charges of the first drive electrode; a second fixed member (1a) disposed on the rear of the first fixed member and opposite the first moving member and having a plurality of second driving electrodes (4a) and an opening on its surface; and a second moving member (24a) with light shield properties disposed between the first fixed member and the second fixed member and movable relative to the second fixed member by receiving drive force produced by the charges of the second driving electrode. In the electrostatic shutter mechanism, a shield electrode (4c) is disposed between the first driving electrode and the second moving member. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrostatic shutter mechanism including a shutter curtain that moves by receiving a driving force due to electric charges of a driving electrode.

As a technique related to the shutter mechanism, a technique is disclosed in which a slider is driven using the principle of operation of an inductive charge actuator and the slider functions as a shutter curtain. In this technique, an electrode is formed on the surface of the glass epoxy substrate and the first slider is disposed opposite to the electrode, and an electrode is also formed on the back surface and the second slider is disposed opposite the electrode (for example, Patent Document 1).
Japanese Patent Laid-Open No. 8-220592

  The technique described in Patent Document 1 describes an example applied to a lens shutter with an aperture function, but it can also be applied as a focal plane type shutter mechanism by using two sliders as a front curtain and a rear curtain. It is possible.

  However, when attempting to reduce the thickness of the focal plane shutter and reduce the thickness of the glass-epoxy substrate, the voltage applied to the drive electrode for driving the first light-shielding curtain affects the operation of the second light-shielding curtain. There is a fear.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an electrostatic shutter mechanism that can reduce the thickness by preventing mutual interference of a plurality of shutter curtain drive mechanisms.

  In order to solve the above-mentioned problems, an electrostatic shutter mechanism according to a first aspect of the present invention includes a first fixing member having a first driving electrode on its surface and an opening, and the first fixing member. A first moving member having a light-shielding property capable of moving relative to the first fixed member by receiving a driving force from the electric charge of the driving electrode; and the first moving member of the first fixed member; The second fixing member, which is disposed on the back side of the opposing surface and has a plurality of second driving electrodes on the surface and has an opening, is sandwiched between the first fixing member and the second fixing member. And a second moving member having a light shielding property capable of moving relative to the second fixed member by receiving a driving force from the electric charge of the second driving electrode. In the shutter mechanism, the first driving electrode and the second driving electrode Placing the shield electrode between the movable member.

  An electrostatic shutter mechanism according to a second aspect of the present invention is the electrostatic shutter mechanism according to the above-described invention, wherein the potential of the shield electrode is a predetermined constant value.

  An electrostatic shutter mechanism according to a third aspect of the present invention is the electrostatic shutter mechanism according to the invention described above, wherein the potential of the shield electrode is 0V.

  An electrostatic shutter mechanism according to a fourth aspect of the present invention is the electrostatic shutter mechanism according to the invention described above, wherein the shield electrode is disposed on the back surface of the surface of the first fixing member facing the moving element. It was.

  An electrostatic shutter mechanism according to a fifth aspect of the present invention is the electrostatic shutter mechanism according to the invention described above, wherein the shield electrode has an insulator between the first drive electrode and the first fixing member. Is arranged through.

  The electrostatic shutter mechanism according to claim 6 of the present invention is the electrostatic shutter mechanism according to the invention described above, wherein the shield electrode is a transparent electrode.

  According to a seventh aspect of the present invention, there is provided an electrostatic shutter mechanism comprising: a fixing member having first and second driving electrodes on the front and back surfaces thereof; A first moving member having a light-shielding property capable of moving relative to the first fixed member by receiving a driving force by the electric charge of the electrode, and an electretized portion; The second moving member having a light shielding property capable of moving relative to the second fixed member by receiving a driving force due to the electric charge, and the first driving electrode and the second driving electrode. And a shield electrode.

  An electrostatic shutter mechanism according to an eighth aspect of the present invention is the electrostatic shutter mechanism according to the invention described above, wherein the potential of the shield electrode is 0V.

  According to the present invention, it is possible to reduce the thickness by preventing mutual interference of a plurality of shutter curtain drive mechanisms.

  First, the driving principle of the shutter device using the shutter mechanism according to the present invention will be described with reference to FIGS.

  The shutter device basically includes a stator 1 and a mover 2, and the mover 2 is configured to be movable in the left-right direction with respect to the stator 1. The stator 1 is provided with an opening 3 for guiding a light image from a subject to an image sensor (not shown), and a plurality of strip-like drive electrodes 4 are arranged in parallel with each other at a predetermined interval. ing. The mover 2 is a light-shielding member, and includes a plurality of permanent-polarized derivatives (hereinafter referred to as electrets), which will be described later, in parallel with the drive electrodes of the stator 1 at predetermined intervals.

  When a frequency voltage is applied to the drive electrode 4 in such a configuration, an attractive force or a repulsive force is generated between the drive electrode 4 and the above-described electret, and as a result, the mover 2 moves relative to the stator 1. To do.

  Therefore, if the movable element 2 is movable so as to open or shield the opening 3 of the stator 1, a shutter device can be configured thereby. (1) in FIG. 1 shows a state in which the shutter is open, and (2) in FIG. 1 shows a state in which the shutter is closed.

  The opening 3 is not necessarily required for the stator 1. The stator 1 is used as a transmissive member, and a region where the drive electrode 4 is not provided, that is, a transmissive region is formed as shown in FIG. You may do it. Hereinafter, this is referred to as an opening for convenience. In addition, the shutter device according to this configuration is referred to as an “electret shutter”.

  The right side of FIG. 2 schematically shows a cross section of the electret shutter. A voltage signal line from the drive circuit 10 is connected to each drive electrode 4 arranged on the stator 1. A four-phase voltage signal is applied to the voltage signal line. Therefore, the same voltage signal is applied to the drive electrodes 4 every four lines. In FIG. 2, the voltage signals are distinguished by attaching the symbols A, B, C, and D to the drive electrode 4.

  The mover 2 is provided with a plurality of permanent-polarized derivatives (electrets) 5 on the surface facing the stator 1.

  In addition, this figure is a schematic diagram to the last, and the number and arrangement interval of electrodes and electret parts in an actual electret shutter are the size of the shutter device, the area of the opening, the polarity of the electret part, the arrangement form, and the shutter device. It is appropriately determined depending on various factors such as required drive resolution and maximum shutter speed. In addition, this electret shutter is a type in which electret portions having positive and negative polarities are alternately arranged, but can be realized only by arranging electret regions of either polarity at predetermined intervals. It is.

  The left side of FIG. 2 shows the configuration of the drive circuit 10 that generates a voltage signal to be applied to the electret shutter. The rectangular wave train (drive pulse signal) generated by the pulse generation circuit 12 is supplied to the booster circuit 14 and the phase shifter 15. The booster circuit 14 boosts the input rectangular wave train to about 100 V, branches it into voltage signals having two polarities, and supplies them to the drive electrodes A and C.

  On the other hand, the rectangular wave train input to the phase shifter 15 has a waveform delayed by 90 °, and is then input to the booster circuit 14 to form two rectangular wave trains similar to those described above, and supplied to the drive electrodes B and D. Is done.

  FIG. 3 shows a voltage signal sequence created by the drive circuit 10 and applied to the drive electrode 4. As for the voltage state of the voltage electrode 4, the four states t1 to t4 change repeatedly corresponding to the passage of time.

  FIG. 4 is a diagram for explaining the operation of the electret shutter.

  (1) in FIG. 4 shows the voltage state of the electret and the drive electrode immediately after switching to t1. The electret 5 a receives a repulsive force from the drive electrode A and receives an attractive force from the drive electrode B. The electret 5 b receives a repulsive force from the drive electrode C and receives a suction force from the drive electrode D. For this reason, the movable element 2 receives a force in the right direction in the figure and moves by one drive electrode pitch d.

  (2) in FIG. 4 shows the voltage state of the electret and the drive electrode immediately after switching to t2. The electret 5 a receives a repulsive force from the drive electrode B and receives an attractive force from the drive electrode C. The electret 5 b receives a repulsive force from the drive electrode D and receives a suction force from the other drive electrode A. For this reason, the movable element 2 receives a force in the right direction in the figure and moves by one drive electrode pitch d.

  (3) in FIG. 4 shows the state of the electret and drive electrode voltage immediately after switching to t3, and (4) in FIG. 4 shows the state of the electret and drive electrode voltage immediately after switching to t4. Show. Similar to the above-described operation, the moving element 2 moves by one drive electrode pitch d. Then, by repeating this operation, the movable element 2 moves to the right in the figure. In order to move the movable element 2 in the left direction in the figure, the polarity of the voltage applied to the drive electrode 4 may be switched in reverse.

[First Embodiment]
FIG. 5 is a perspective view illustrating a configuration of an imaging module using the shutter mechanism according to the first embodiment of the present invention, and FIG. 6 is a cross-sectional view of the imaging module.

  The imaging module includes a shutter device 21 and an imaging unit 22.

  The shutter device 21 is a focal plane shutter having a light-shielding curtain (front curtain) 24a and a light-shielding curtain (rear curtain) 24b that travel independently. The light shielding curtains 24a and 24b are provided with the above-described electret 5 (not shown). Further, stators 1a and 1b provided with a plurality of drive electrodes 4a and 4b and openings (or transmission parts) are arranged on the opposing surface side of each electret 5.

  A stator 1b is provided at the center of the shutter device 21, and light-shielding curtains 24a and 24b are provided on both sides of the stator 1b. Further, a stator 1a provided with a drive electrode 4a so as to sandwich the light shielding curtain 24a and a protective member 25 provided with an opening (or transmission part) so as to sandwich 24b are fixedly provided on the outside thereof. In addition, spacers 31 to 32 having elasticity are provided between the stator 1b and the protection member 25, and spacers 33 to 34 having elasticity are provided between the stator 1b and the stator 1a.

  FIG. 7 is a longitudinal sectional view showing a detailed configuration of the shutter device 21. In the shutter device 21 of the present embodiment, the shield electrode 4c is provided on the back surface of the surface on which the drive electrode 4b of the stator 1b is provided. The shield electrode 4c is maintained at a constant voltage by the power supply voltage.

  Then, the effect | action of a shield electrode is demonstrated.

  FIG. 8 is a cross-sectional view showing a detailed configuration of the shutter device 21. As described above, alternating voltage signals are applied to the drive electrodes 4a and 4b, respectively, thereby generating + or-voltages on the drive electrodes 4a and 4b, respectively. As a result, the shutter device 21 has an electrostatic field due to the potentials of these electrodes.

  Accordingly, when the distance between the stator 1a and the stator 1b is narrow, the electrostatic field generated by the drive electrode 4b affects the light shielding curtain 24a and causes interference. Therefore, this interference can be prevented by providing the shield electrode 4c made of a conductor between the drive electrode 4b and the light shielding curtain 24a and keeping the potential of the shield electrode 4c at a predetermined potential.

  Here, copper, aluminum, or the like is used as the conductor, but the material is not limited to this, and any material that can easily conduct electricity can be used. In FIG. 7, the power supply voltage is applied to the shield electrode 4c. However, the shield electrode 4c is not limited to the power supply voltage, and a constant voltage may be applied. Therefore, the shield electrode 4c may be grounded.

  In FIG. 7, the shield electrode 4c is provided on a part of the stator 1b. However, as shown in FIG. 9, it may be provided on the entire surface of the stator 1b.

  The imaging unit 22 is configured by accommodating and fixing an imaging element 27 and a signal line 28 in a storage container 26 and covering the subject side of the storage container 26 with a cover glass 29 having an opening (transmission part). In the present embodiment, for the sake of explanation, the figure shows a sufficient distance between the image pickup surface of the image pickup device 27 and the cover glass 29, but this is ideally minimal from the viewpoint of shutter efficiency. is there.

  In the imaging module of the present embodiment, since the shutter device 21 is configured using an electret shutter, the thickness thereof can be greatly reduced as compared with a conventional shutter unit, and the thickness can be reduced. . Since the shield electrode 4c is provided between the drive electrode 4b and the light-shielding curtain 24a to prevent interference, the distance between the stators 1a and 1b can be narrowed, and the thickness can be further reduced. .

  The electret shutter does not use charges induced in the light shielding curtains 24a and 24b, but uses charges that are permanently polarized in the electret, so that the rise time can be shortened and the shutter operation speeded up. it can.

  In addition, since the electret charge amount can be arbitrarily given, an optimum charge amount that maximizes the driving force can be given, and an extremely large driving force can be obtained. Therefore, it is possible to configure an optimal shutter device 21 corresponding to the size of the imaging module.

  Further, the light shielding curtains 24a and 24b are lightweight because a resin material can be used as a raw material. Specifically, the light shielding curtains 24a and 24b can be formed of a thin film of 10 to 25 μm. Therefore, the amount of power required for the operation is small, and a quiet operation can be realized.

  In the shutter device 21 according to the present embodiment, a method of driving the electret film is employed, but a method of inducing charges in the high resistance as described in Patent Document 1 may be employed. .

  FIG. 10 is a diagram for explaining the operation of the light-shielding curtains 24a and 24b.

  In the initial state shown in (1) of FIG. 10, the exposure aperture (light flux passage region) is fully closed. That is, the front curtain 24a covers the entire exposure aperture, and completely blocks the image pickup unit 22 from subject light. Next, as shown in FIG. 10B, the front curtain 24a is driven in the direction of the arrow in the drawing in response to the start instruction of the shooting operation, and the exposure aperture is fully opened, and the subject light is guided to the imaging unit 22. It is burned. When a predetermined time has elapsed, as shown in FIG. 10 (3), the rear curtain 24b is driven in the direction of the arrow in the figure to block the exposure opening. Thereafter, the front curtain 24a and the rear curtain 24b return to the initial state shown in (1) of FIG. 10, and wait for the next photographing operation.

  Note that the present shutter device can be applied not only to the shutter of a camera but also to various objects. For example, the present device may be used as an aperture control device, that is, an aperture device.

[Second Embodiment]
In the second embodiment, the configuration of the shutter device 21 is different from that of the first embodiment. Accordingly, the same parts as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 11 is a diagram illustrating a detailed configuration of the shutter device 21 using the shutter mechanism according to the second embodiment. In FIG. 11, the stator 1b is different from the first embodiment in that the shield electrode 4c and the drive electrode 4b are provided on the same surface. The shield electrode 4c and the drive electrode 4b are arranged via an insulator 11 so as not to be electrically connected to each other.

  According to the present embodiment, since the shield electrode 4c is provided on the surface opposite to the light shielding curtain 24a, the travel is not hindered. In FIG. 11, the shield electrode 4c is grounded, but may be kept at a predetermined constant potential as described above.

[Third Embodiment]
In the third embodiment, the configuration of the shutter device 21 is different from that of the first embodiment. Accordingly, the same parts as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 12 is a diagram showing a detailed configuration of the shutter device 21 using the shutter mechanism of the third embodiment. In FIG. 12, the point which uses the transparent electrode for the shield electrode 4c differs from 1st Embodiment. ITO (Indium Tin Oxide) can be used for the transparent electrode. Indium tin oxide is suitable as the shield electrode 4c because it has electrical conductivity, can easily conduct electricity, and has a property of allowing visible light to pass through. Further, indium tin oxide can be formed as a thin film by sputtering on the stators 1a and 1b in the same manner as the drive electrodes 4a and 4b, so that it can be manufactured by being incorporated into a series of steps.

  According to the present embodiment, since it is not necessary to provide an opening in the shield electrode 4c, the shielding effect can be enhanced. Further, the manufacturing process for providing the opening can be omitted.

[Fourth Embodiment]
In the fourth embodiment, the configuration of the shutter device 21 is different from that of the first embodiment. Accordingly, the same parts as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 13 is a diagram showing a detailed configuration of the shutter device 21 in which the shutter mechanism of the third embodiment is used.

  A shield electrode 4c is provided at the center of the shutter device 21, and stators 1a and 1b are disposed on both sides (both sides) of the shield electrode 4c. Further, driving electrodes 4a and 4b are provided on the outer surfaces of the stators 1a and 1b, and protective members are provided with openings (or transmission parts) sandwiching the light shielding curtains 24a and 24b arranged on the outer sides thereof. 25 is fixed. In addition, spacers 31 to 34 having elasticity are provided between the protective member 25 and the stators 1a and 1b, respectively.

  According to the present embodiment, since the shield electrode 4c is provided on the back surfaces of the fixing members 1a and 1b, the strength of the fixing members 1a and 1b can be reduced. Therefore, since it is not necessary to use glass for the fixing members 1a and 1b, the shutter device 21 can be further thinned by reducing the thickness thereof.

  FIG. 14 is a block diagram showing a system configuration of a camera using the shutter device according to each of the above-described embodiments.

  This camera system records a body unit 100 as a camera body, an accessory device (hereinafter abbreviated as “accessory”), for example, a lens unit (that is, a lens barrel) 112 as an interchangeable lens, and captured image data. A recording medium 139 to be stored, an external strobe unit 80, and the like.

  The lens unit 112 can be detachably attached via a lens mount (not shown) provided on the front surface of the body unit 100.

  The recording medium 139 is an external recording medium such as various memory cards or an external HDD, and is mounted so as to be communicable with the camera body via the communication connector 135 and exchangeable.

  The strobe unit 180 includes a flash light emitting unit 181, a DC / DC converter 182, a strobe control microcomputer 183, and a battery 184, and can be attached to the camera body via a strobe communication connector 185.

  The lens unit 112 is controlled by a lens control microcomputer (hereinafter referred to as “Lucom”) 105. The body unit 100 is controlled by a body control microcomputer (hereinafter referred to as “Bucom”) 150. The Lucom 105 and Bucom 150 are electrically connected to each other via the communication connector 106 when they are combined. As a camera system, the Lucom 105 is operated in cooperation with the Bucom 150 in a dependent manner.

  In the lens unit 112, photographing lenses 112a and 112b and a diaphragm 103 are provided. The taking lens 112a is driven by a DC motor (not shown) in the lens driving mechanism 102. The diaphragm 103 is driven by a stepping motor (not shown) in the diaphragm drive mechanism 104. The Lucom 105 controls each of these motors in accordance with a command from the Bucom 150.

  The following structural members are arranged in the body unit 100 as shown in the figure. For example, a single-lens reflex system component (penta prism 113a, quick return mirror 113b, eyepiece lens 113c, sub-mirror 113d) as an optical system, the imaging module 20, and a reflected light beam from the sub-mirror 113d are automatically measured. For this purpose, an AF sensor unit 130a is provided. The imaging module 20 includes a focus plane type shutter device 21 on the optical axis and an imaging unit 22 that houses a CCD for photoelectrically converting a subject image that has passed through the optical system.

  Further, the AF sensor driving circuit 130b for driving and controlling the AF sensor unit 130a, the mirror driving mechanism 118 for driving and controlling the quick return mirror 113b, and the movement of the front curtain 24a and the rear curtain 24b of the shutter device 21 are controlled. A shutter drive control circuit 148 and a photometric circuit 132 that performs photometric processing based on the light flux from the pentaprism 113a are provided.

  The shutter drive control circuit 148 exchanges a signal for controlling the opening / closing operation of the shutter and a signal for synchronizing with the strobe with the Bucom 150.

  The camera system is also provided with a CCD interface circuit 134 connected to the imaging unit 22, a liquid crystal monitor 136, an SDRAM 138 provided as a storage area, a recording medium 139, and an image processing controller 140 that performs image processing. The electronic recording display function can be provided together with the electronic imaging function.

  The Bucom 150 is provided with an operation display LCD 157 for notifying the user of the operation state of the camera by display output, and a camera operation SW 152. The camera operation SW 152 is a switch group including operation buttons necessary for operating the camera, such as a release SW, a mode change SW, and a power SW. Further, a battery 154 as a power source and a power circuit 153 for converting the voltage of the power source into a voltage required for each circuit unit of the camera system and supplying the same are provided.

  Each part of the camera system configured as described above operates as follows.

  The mirror driving mechanism 118 is a mechanism for driving the quick return mirror 113b to the UP position and the DOWN position. When the quick return mirror 113b is at the DOWN position, the light flux from the photographing lenses 112a and 112b is the AF sensor unit 130a. Is divided and led to the pentaprism 113a side.

  The output from the AF sensor in the AF sensor unit 130a is transmitted to the Bucom 50 via the AF sensor driving circuit 130b, and a known distance measurement process is performed.

  The eyepiece 113c adjacent to the pentaprism 113a allows the user to see the subject, and part of the light beam that has passed through the pentaprism 113a is guided to a photosensor (not shown) in the photometry circuit 132, where it is detected. A well-known photometric process is performed based on the light quantity.

  The shutter drive control circuit 148 receives a signal for controlling the driving of the shutter from the Bucom 150, controls the shutter device 21 based on the signal, and outputs a strobe tuning signal for causing the Bucom 150 to emit a strobe at a predetermined timing. Output. The Bucom 150 outputs a light emission command signal to the strobe unit 80 by communication based on the strobe tuning signal.

  The image processing controller 140 controls the CCD interface circuit 134 in accordance with an instruction from the Bucom 150 to capture image data from the imaging unit 22. The image data is converted into a video signal by the image processing controller 140 and output and displayed on the liquid crystal monitor 136. The user can confirm the captured image from the display image on the liquid crystal monitor 136.

  The SDRAM 138 is a memory for temporarily storing image data, and is used as a work area when image data is converted. The image data is set to be stored in the recording medium 139 after being converted into JPEG data.

  The shutter device according to the first embodiment of the present invention includes the shutter device 21 and the shutter drive control circuit 148 shown in FIG.

  FIG. 15 is a configuration diagram showing signal connection between the shutter drive control circuit 148 and the shutter device 21. The shutter device 21 is provided with the front curtain 24a and the rear curtain 24b as described above, and two drive circuits having the configuration shown in FIG. 2 are provided to drive the respective light shielding curtains.

  The pulse generation circuit 12 drives the front curtain 24a and the rear curtain 24b based on the opening / closing control signal from the Bucom 150, and controls the full opening / closing operation of the exposure opening shown in FIG. When a reset signal is received from the Bucom 150, the front curtain 24a and the rear curtain 24b are driven to the initial state. Further, the pulse generation circuit 12 outputs a strobe tuning signal to the Bucom 150 at a predetermined timing.

  Subsequently, an imaging control method using the shutter device according to the first embodiment will be described.

  FIG. 16 is a flowchart showing a schematic photographing operation procedure of the Bucom 150. This operation shows an operation procedure from the release operation to image data generation in the processing procedure of the electronic camera.

  When the user presses the release button one step, this process starts. First, photometric processing is executed (S01). That is, the luminance information of the subject measured by the photometry circuit 132 is acquired. Then, an exposure amount calculation is executed based on the luminance information, and an appropriate aperture value (AV: aperture value) and shutter speed (TV: time value) are calculated (S02).

  Next, AF processing is executed (S03). The light flux from the subject is received by the AF sensor unit 130a via the quick return mirror 113b and the sub mirror 113d, and the deviation amount of the received subject image is output to the Bucom 150 via the AF sensor drive circuit 130b. The Bucom 150 calculates a lens shift amount from the shift amount of the subject image, and transmits the calculated value to the Lucom 105 via the communication connector 106. The Lucom 105 adjusts the focus by moving the photographing lens 112a via the lens driving mechanism 102 based on the amount of lens displacement.

  It is checked whether the release button is further pressed (two steps) with the focus adjusted (S04).

  If the release button has not been pressed down by two steps (No in S04) and the release button is in the state of pressing down by one step (S05 Yes), the process waits until the release button is pressed down by two steps. However, if the release button has not been pressed down by two steps (S04 No) and the release button has not been pressed down by one step (S05 No), it is determined that the user has stopped the shooting operation and the process is terminated. To do.

  When the release button is pressed down two steps (S04 Yes), the photographing operation is continued and the narrowing drive is executed (S06). That is, the Bucom 150 transmits the AV value to the Lucom 105 via the communication connector 106. The Lucom 105 controls the diaphragm 103 via the diaphragm driving mechanism 104 based on the sent AV value.

  Next, mirror-up driving is executed (S07). That is, the quick return mirror 113b is flipped up via the mirror driving mechanism 118 to secure the photographing optical path. Thereafter, an instruction is output to start the imaging operation to the image sensor interface circuit 134 (S08). The imaging element interface circuit 134 operates the imaging element 27 of the imaging unit 22 based on this instruction.

  After the above operation, the Bucom 150 executes a shutter control operation. The shutter control operation will be described with reference to the shutter control time chart at the time of fully open exposure shown in FIG.

  The Bucom 150 outputs a shutter open signal to the shutter drive control circuit 148 (S09). That is, the signal level of the open / close control signal in FIG. 17 is made active. In response to this, the pulse generation circuit 12 of the shutter drive control circuit 148 starts outputting the front curtain drive pulse in order to drive the front curtain 24a. Corresponding to the number of pulses of the front curtain drive pulse, the front curtain 24a is driven in the opening direction from the fully closed position of the exposure opening as shown in the front curtain opening waveform of FIG. Thereafter, a timer for seconds is started (S10).

  Next, the Bucom 150 checks whether or not the exposure time has elapsed (S11).

  If the exposure time has not elapsed (No in S11), it is checked whether or not the strobe tuning signal shown in FIG. 17 is output from the shutter drive control circuit 148 (S12), and waits until the strobe tuning signal is output (S12). No, S11). The strobe tuning signal is output from the shutter drive control circuit 148 at the timing when the leading curtain 24a reaches a position where the exposure opening is fully opened.

  As described above, the front curtain 24a (and the rear curtain 24b) configured using the electret is extremely light, and therefore, the front curtain 24a can be driven with high accuracy and high speed by the front curtain drive pulse. Therefore, it is not necessary to detect whether or not the exposure opening is fully opened by using other detection means, and it can be determined by counting the number of front curtain drive pulses.

  Therefore, as shown in FIG. 17, the shutter drive control circuit 148 outputs a strobe tuning signal (rectangular signal) to the Bucom 150 at the timing when a predetermined number (m) of the front curtain drive pulses are output.

  When it is detected that the strobe tuning signal is activated, the Bucom 150 outputs a light emission control signal that instructs the strobe unit 180 to emit light (S14). If a light emission control signal has already been output, control is performed so that the light emission control signal is not output again (S13).

  If the exposure time has elapsed (S11 Yes), the Bucom 150 outputs a shutter close signal (S15). That is, the signal level of the open / close control signal is made non-active. In response to this, the pulse generation circuit 12 of the shutter drive control circuit 148 starts outputting the rear curtain drive pulse for driving the rear curtain 24b. According to the number of rear curtain drive pulses, the rear curtain 24b is driven from the fully open position of the exposure opening toward the fully closed position, as shown in the rear curtain opening waveform of FIG.

  Next, the Bucom 150 outputs an instruction to the imaging element interface circuit 134 to stop the imaging operation (S16). The imaging element interface circuit 134 stops the imaging operation of the imaging element 27 of the imaging unit 22 based on this instruction.

  Further, the Bucom 150 outputs a reset signal to the shutter drive control circuit 148 (S17). In response to this, the pulse generation circuit 12 of the shutter drive control circuit 148 drives the front curtain 24a and the rear curtain 24b to the initial positions.

  After the shutter control operations from step S09 to step S17 are completed, the image processing controller 140 is instructed to execute image data processing (S18). The image processing controller 140 AD-converts a signal from the image sensor interface circuit 134 to generate image data, processes the image data, and records it on the recording medium 139 via the communication connector 135.

  The Bucom 150 then lowers the quick return mirror 113b via the mirror drive mechanism 118 (S19), and instructs the Lucom 105 to fully open the aperture 103 via the aperture drive mechanism 104 (S20). Then, the imaging operation is terminated.

  FIG. 18 is a shutter control time chart at the time of slit exposure.

  When the brightness of the subject is high, the exposure time may elapse before the front curtain 24a is fully opened. At this time, the shutter drive control circuit 148 outputs the trailing curtain drive pulse without outputting the strobe tuning signal. In this case, the exposure opening is not fully opened, and the slit opening formed by the front curtain 24a and the rear curtain 24b moves on the exposure opening. The imaging operation at the time of slit exposure is the same as the flow shown in FIG.

  Since the shutter device according to the embodiment described above is configured using the electret shutter, the light-shielding curtain can be controlled at a higher speed and with higher accuracy than a shutter device using a conventional stepping motor.

  In addition, since it is not necessary to use a stepping motor for driving the light-shielding curtain, the shutter device can be reduced in weight and further reduced in thickness. Therefore, it is possible to reduce the size and weight of a camera incorporating this shutter device.

  In addition, since this shutter device has low power consumption, it can save energy and resources.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

The figure which shows the shutter mechanism which concerns on this invention. The figure which shows the basic composition of an electret shutter. The figure which shows the voltage signal sequence applied to a drive electrode. The figure explaining operation | movement of an electret shutter. 1 is a perspective view illustrating a configuration of an imaging module using a shutter mechanism according to a first embodiment of the present invention. Sectional drawing of an imaging module. The longitudinal cross-sectional view which shows the structure of the detail of a shutter apparatus. FIG. 3 is a cross-sectional view illustrating a detailed configuration of a shutter device. The figure which shows the structure of a shield electrode. The figure explaining operation | movement of a light-shielding curtain. The figure which shows the structure of the detail of the shutter apparatus using the shutter mechanism of 2nd Embodiment. The figure which shows the structure of the detail of the shutter apparatus using the shutter mechanism of 3rd Embodiment. The figure which shows the structure of the detail of the shutter apparatus using the shutter mechanism of 4th Embodiment. 1 is a block diagram showing a system configuration of a camera using a shutter device according to each embodiment of the present invention. The block diagram which shows the signal connection of a shutter drive control circuit and a shutter unit. The flowchart which shows the general | schematic imaging operation procedure of the microcomputer for body control. The figure which shows the shutter control time chart at the time of full open exposure. The figure which shows the shutter control time chart at the time of slit exposure.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Stator, 2 ... Moving element, 3 ... Opening part (transmission part), 4a ... Drive electrode, 4b ... Drive electrode, 4c ... Shield electrode, 5 ... Electret, 10 ... Drive circuit, 12 ... Pulse generation circuit, 14 DESCRIPTION OF SYMBOLS ... Boosting circuit, 20 ... Imaging module, 21 ... Shutter device, 22 ... Imaging unit, 24 ... Light-shielding curtain, 25 ... Protection member, 27 ... Imaging element, 31 ... Spacer.

Claims (8)

A first fixing member having a first drive electrode on the surface and an opening;
A first moving member having a light-shielding property capable of moving relative to the first fixed member by receiving a driving force from the charge of the first driving electrode;
A second fixing member that is disposed on the back side of the surface of the first fixing member that faces the first moving member, and has a plurality of second driving electrodes on the surface and has an opening;
It is arranged so as to be sandwiched between the first fixing member and the second fixing member, and receives a driving force by the electric charge of the second driving electrode, and can move relative to the second fixing member. In the electrostatic shutter mechanism configured by the second moving member having a light shielding property,
An electrostatic shutter mechanism, wherein a shield electrode is disposed between the first driving electrode and the second moving member.   2. The electrostatic shutter mechanism according to claim 1, wherein the potential of the shield electrode is a predetermined constant value.   The electrostatic shutter mechanism according to claim 1, wherein the potential of the shield electrode is 0V.   The electrostatic shutter mechanism according to claim 1, wherein the shield electrode is disposed on a back surface of a surface of the first fixing member facing the moving element.   The electrostatic shutter mechanism according to claim 1, wherein the shield electrode is disposed between the first drive electrode and the first fixing member via an insulator.   The electrostatic shutter mechanism according to claim 1, wherein the shield electrode is a transparent electrode. A fixing member having first and second drive electrodes on the front and back surfaces, respectively;
A first moving member having an electret portion, receiving a driving force from the electric charge of the first driving electrode, and having a light shielding property capable of moving relative to the first fixing member;
A second moving member having an electretized portion, receiving a driving force by the electric charge of the second driving electrode, and having a light shielding property capable of moving relative to the second fixing member;
An electrostatic shutter mechanism comprising a shield electrode disposed between the first drive electrode and the second drive electrode.   8. The electrostatic shutter mechanism according to claim 7, wherein the potential of the shield electrode is 0V.

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