JP2005077782A - Aperture control mechanism, imaging device, and aperture control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control the apertures of a shutter and a stop with a simple constitution, even if an electrification contraction member of shape memory alloy, etc., is used. <P>SOLUTION: Through the contraction of the electrification contraction member 21, blade plates 15 and 16 are opened against the energizing force of an elastic member 20. Then one end of the electrification contraction member 21 is moved to release the energizing force by the electrification contraction member 21. Further, a current, flowing to the shape memory alloy as the electrification contraction member 21, is detected, and the electrification contraction member 21 is supplied with electric power so that the magnitude of aperture reaches a desired quantity, the amount of the supplied electric power being determined on the basis of the value of the detected current and the current value, corresponding to a desired magnitude of aperture. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an aperture control mechanism, an imaging apparatus, and an aperture control method for controlling an aperture amount through which light passes in an optical system of a still camera, a digital still camera, a video camera, and other cameras.

  Patent Document 1 discloses a shutter opening control mechanism. In the opening control mechanism of Patent Document 1, two wing plates, a front wing plate and a rear wing plate, are used, and each wing plate is set at a locking position by energizing the shape memory alloy. Each shape memory alloy is energized to release the engagement of each slat in turn. When the locking is released, each slat rotates with the restoring force of the spring. As a result, an opening through which light from the lens passes is formed during the period from when the leading blade is rotated to when the trailing blade is rotated.

  In Patent Document 2, for example, a leaf spring is connected to a diaphragm blade plate in which two openings of different sizes are formed, and the shape of the leaf spring is extended in opposite directions to connect two shape memory alloys. An opening control mechanism is disclosed. And in the opening control mechanism of this patent document 2, by energizing either one of the two shape memory alloys, one of the two openings is arranged at a position where light from the lens passes. By energizing the other of the two shape memory alloys, the other of the two openings is disposed at a position where light from the lens passes. Thereby, the aperture of the diaphragm can be switched in two stages.

  Further, in Patent Document 2, the recovery displacement amount of the shape memory alloy can be controlled by controlling the duty ratio of the energization time of the shape memory alloy, and the diaphragm blade can be controlled to an arbitrary position between two points. It is disclosed.

Japanese Patent Laid-Open No. 10-123583 (Detailed Description of the Invention, FIGS. 1 and 2) JP-A-6-230457 (detailed description of the invention, drawings)

  As described above, the conventional opening control mechanism controls the opening of the shutter and the diaphragm by utilizing the contraction of the shape memory alloy.

  By the way, the shape memory alloy can be contracted at a high speed by being heated by energization, and can be used for opening control of a shutter and a diaphragm.

  However, when a shape memory alloy is used as described above, the shape memory alloy has a contraction speed that is fast enough to control the opening of the shutter and the diaphragm, but it is stretched to its original length after stopping energization. Since it takes time to do so, the conventional opening control mechanism requires a complicated mechanism for executing both the opening expanding operation and the closing operation.

  The present invention has been made based on the above-described problem, and an aperture control mechanism and an imaging apparatus capable of controlling the aperture of a shutter and a diaphragm with a simple configuration even when a current-shrinking member such as a shape memory alloy is used. And an opening control method.

  The opening control mechanism according to the present invention includes at least a shutter slat, an elastic member that urges the slat in the direction of closing the slat opening, and contracts by energization. An energizing and contracting member that urges and opens against the energizing force, and a release means that releases the energizing force by the energizing and contracting member by moving the end of the energizing and contracting member after the opening of the slats by the energizing and contracting member. It is to be prepared.

  If this configuration is adopted, the opening can be controlled regardless of the extension time even if it takes time to extend the energization contraction member. Therefore, it is possible to control the opening of the shutter and the diaphragm by energizing the energization contracting member with a simple configuration.

  Another opening control mechanism according to the present invention includes a wing plate that is rotatably or movably disposed to form an opening through which light from a lens passes, and the wing in a state where the opening is minimized. A regulating member that abuts against the slats or the slats without opening, a first elastic member that applies a force to the slats to abut the slats against the regulating member, and a movable member that is rotatably or movably disposed The holding means for holding the movable member in a predetermined position by energization, the movement of the slats and the movable member are connected so as to be interlocked, and the energization contraction is contracted in a direction opposite to the biasing direction by the first elastic member by energization. By energizing the member, the holding means and the energizing contraction member, the blade is rotated or moved in a direction away from the regulating member to open a predetermined amount, and then the energization to the holding means is stopped. Those having a control means for rotating or moving the Haneban in a direction to abut on the restricting member by the restoring force of the one elastic member.

  By adopting this configuration, even if it takes time to expand the energizing / shrinking member, the opening can be controlled by the operation of the holding unit based on the control of the control unit regardless of the expansion time. Therefore, it is possible to control the opening of the shutter and the diaphragm by energizing the energization contracting member with a simple configuration.

  In another opening control mechanism according to the present invention, in addition to the configuration of the above-described invention, when the energizing / shrinking member is not energized, the wing plate is in contact with the regulating member, and the movable member is brought into a predetermined position by the holding means. The second elastic member is formed to have a length that can be held and pulls the movable member to a predetermined position in a state where the holding means is not energized.

  If this configuration is adopted, the movable member does not move, so that chattering due to the moment of inertia of the rotor, etc., as in the case where the opening is controlled by rotating the rotor such as a stepping motor or iris motor, etc. It does not occur and the slats can be driven stably.

  Another opening control mechanism according to the present invention includes a detector that detects a current flowing through the energization contracting member as a detection current in addition to the configuration of each of the above-described inventions, and the energization contracting member contracts due to heat caused by energization. In addition, the shape memory alloy whose resistance value increases or decreases, and the slats are disposed so as to be rotatable or movable until the opening disappears, and the control means determines the opening amount based on the value of the detected current, The timing for stopping the energization of the holding means is controlled based on the timing at which the opening starts to be formed.

  By adopting this configuration, the energizing / shrinking member can be formed so that no opening is formed even if the energizing / shrinking member contracts due to its environmental temperature. Thereby, inadvertent exposure can be prevented. Further, since the timing of stopping energization to the holding means is controlled based on the timing at which the opening starts to be formed, the period from the start of energization to the energization contracting member until the opening starts to be formed depends on the environmental temperature. Even if it fluctuates, the opening time and the exposure amount can be made accurate.

  In another opening control mechanism according to the present invention, in addition to the configuration of each of the above-described inventions, the control unit measures time from the timing when the detected current becomes current when the opening starts to be formed, and the time is measured in advance. When the time corresponding to the determined exposure amount is reached, the energization to the holding means is stopped.

  By adopting this configuration, it is possible to accurately set the exposure amount to a desired amount while preventing inadvertent exposure.

  Another opening control mechanism according to the present invention includes a detector that detects a current flowing through the energization contracting member as a detection current in addition to the configuration of each of the above-described inventions, and the energization contracting member contracts due to heat caused by energization. In addition, the shape memory alloy whose resistance value increases or decreases, and the control means determines the opening amount based on the value of the detected current, and when the opening amount reaches a desired size, the energization of the energization contracting member is stopped. Is.

  If this configuration is adopted, the opening amount can be controlled to a desired size. Thereby, the aperture amount of the diaphragm can be controlled steplessly based on the detected current, for example.

  In addition to the configuration of each of the inventions described above, the opening control mechanism according to the present invention is configured such that the control unit periodically performs pulsed energization on the energization contracting member after stopping energization of the energization contraction member. When the detected current due to normal energization is smaller than the current when the opening amount becomes the desired size, the energizing contraction member is energized until the detected current becomes the current when the opening amount becomes the desired size It is.

  If this structure is employ | adopted, the opening amount by shrinkage | contraction of an electricity supply shrinkable member can be maintained at a desired magnitude | size.

  In another opening control mechanism according to the present invention, in addition to the configuration of each of the above-described inventions, the control means has a cycle shorter than the time when the energized contracting member contracts due to cooling by the ambient temperature and the desired opening amount cannot be maintained. The energization contracting member is periodically energized.

  If this configuration is adopted, before the energization contracting member starts to contract by cooling, the energization contracting member is heated to a predetermined temperature, and the opening amount due to the contraction of the energizing contraction member is maintained at a desired constant size. Can do.

  Another opening control mechanism according to the present invention includes a non-volatile memory that stores a plurality of current values corresponding to the sizes of the plurality of openings in addition to the configuration of each of the above-described inventions, and the control means includes a detection current. And the energization of the energization contracting member is controlled based on a comparison between the value of the current and a current value selected from the plurality of current values.

  If this structure is employ | adopted, the opening amount by shrinkage | contraction of an electricity supply shrinkable member can be controlled to either of the predetermined some opening amount. In addition, since a plurality of current values corresponding to a plurality of opening amounts are stored in the nonvolatile memory, it is possible to easily cope with a change in the specifications of the camera, etc. by simply replacing or rewriting the nonvolatile memory.

  Another opening control mechanism according to the present invention includes, in addition to the configurations of the above-described inventions, a detector that detects a current flowing through the energization contracting member as a detection current and a flash circuit that emits flash light. When the contracting member is a shape memory alloy that contracts due to heat caused by energization and the resistance value increases or decreases, and the control means, when the detected current becomes a current when the size of the opening becomes a desired size, The flash circuit emits flash light.

  By adopting this configuration, it is possible to reliably emit flash light in a state where the aperture is opened to a desired size. Therefore, the amount of flash light passing through the opening can be set to an appropriate amount as calculated compared to the case where the flash circuit emits light at a timing when the shutter is not fully opened.

  Still another opening control mechanism according to the present invention includes at least a shutter slat, an elastic member that biases the slat in a direction to open the slat opening, and contracts by energization. An energizing / shrinking member that urges and closes against the urging force of the elastic member, and a release means that releases the urging force of the energizing / shrinking member by moving the end of the energizing / shrinking member after the wing plate is closed by the energizing / shrinking member. Are provided.

  If this configuration is adopted, the opening can be controlled regardless of the extension time even if it takes time to extend the energization contraction member. Therefore, it is possible to control the opening of the shutter and the diaphragm by energizing the energization contracting member with a simple configuration.

  Still another opening control mechanism according to the present invention includes a wing plate, a shape memory alloy that contracts due to heat caused by energization and increases or decreases in resistance and drives the wing plate to adjust the opening amount, and during energization. Based on the detector that detects the current flowing in the shape memory alloy and the current value detected by the detector and the current value corresponding to the desired opening amount, the shape memory is set so that the opening amount becomes a desired opening amount. And a control means for controlling a current value to be passed through the alloy.

  If this configuration is adopted, the opening amount can be controlled without detecting the position of the slats or the ambient temperature, so that the opening control can be performed with a simple configuration. In addition, the amount of contraction of the shape memory alloy can be measured in real time based on the resistance value during energization.

  An imaging apparatus according to the present invention includes an optical system for imaging, a light receiving unit that receives an image obtained through the optical system, and any one of the above-described ones that controls exposure of the light transmitted through the optical system to the light receiving unit. Two opening control mechanisms.

  By adopting this configuration, even if it takes time to expand the energizing / shrinking member, the opening can be controlled by the operation of the holding unit based on the control of the control unit regardless of the expansion time. Therefore, it is possible to control the opening of the shutter and the diaphragm by energizing the energization contracting member with a simple configuration.

  According to the opening control method of the present invention, an elastic member is used to bias at least the opening of a slat for a shutter with an elastic member, and the slat is attached to the elastic member by contraction using an energized contraction member that contracts by energization. The energizing contraction member is released by energizing and opening it, and after the opening of the slats by the energizing contraction member, the end of the energization contraction member is moved.

  If this method is employed, the opening can be controlled by the operation of the holding means regardless of the extension time, even if it takes time to extend the energizing and contracting member. Therefore, it is possible to control the opening of the shutter and the diaphragm by energizing the energization contracting member with a simple configuration.

  In the present invention, the opening of the shutter and the diaphragm can be controlled with a simple configuration even when a current-shrinking member such as a shape memory alloy is used.

  Hereinafter, an aperture control mechanism, an imaging device, and an aperture control method according to an embodiment of the present invention will be described with reference to the drawings. In the following embodiments, a still camera will be described as an example of an imaging device. The opening control mechanism will be described as a part of the configuration of the still camera. The aperture control method will be described as a part of the operation of the still camera.

Embodiment 1 FIG.
The still camera according to Embodiment 1 has a housing. The still camera according to the first embodiment includes a lens device, a film device, and a shutter device in the housing.

  The lens device has an optical system composed of one or a plurality of lenses, and forms an image of light incident from the optical axis direction of these lenses.

  In the film device, a film as a light receiving unit wound around a film holder is arranged on the focal plane of the lens device or before and after the focal plane in accordance with the rotation of the winding lever. Instead of this film device, for example, an electronic light receiving element such as a charge coupled device (CCD) may be disposed as a light receiving portion on the focal plane of the lens device or on the front and back of the focal plane.

  The shutter device includes a shutter mechanism 1 (see FIG. 1) described later, a shutter drive circuit 35 (see FIG. 3), and a shutter control unit. The shutter control unit of the first embodiment is realized as a part of a camera control unit 71 described later.

  FIG. 1 is a front view showing a shutter mechanism of a still camera according to Embodiment 1 of the present invention.

  The shutter mechanism 1 has a flat shutter reference plate 11. A shutter opening 12 is formed in the shutter reference plate 11 in a circular shape. The shutter opening 12 is formed in a size corresponding to the aperture value at the maximum opening of the still camera. The shutter reference plate 11 is formed between the lens device and the film device so that the circular center of the shutter opening 12 coincides with the optical axis of the lens device and the shutter opening 12 is perpendicular to the optical axis of the lens device. Arranged between.

  On the shutter reference plate 11, two rotation shafts 13 and 14 are erected in parallel with each other at a position equidistant from the circular center of the shutter opening 12. These two rotation axes are located on the left side of the shutter opening 12 in FIG.

  A first shutter blade 15 as a blade is disposed on one of the two rotation shafts 13 and 14 (rotation shaft on the upper side in FIG. 1; hereinafter referred to as a first rotation shaft) 13. It is pivotally supported. A second shutter blade 16 as a blade is rotatable on the other of the two rotation shafts (rotation shaft on the lower side in FIG. 1, hereinafter referred to as a second rotation shaft) 14. Is pivotally supported.

  The first shutter blade 15 has a semi-annular portion 15a, a connecting portion 15b, a round hole 15c, a long hole 15d, and a cutout portion 15e. The semi-annular portion 15a has, for example, an annular shape having an inner diameter that is substantially the same radius as the shutter opening 12 and an outer diameter that is three or more times larger than the radius, and is approximately half to approximately ¼ of the annular shape. The shape has a notch.

  The connecting portion 15b of the first shutter blade 15 has a substantially rectangular shape, and a round hole 15c is formed at a corner on one end side in the longitudinal direction, and to the semi-annular portion 15a at the other end in the longitudinal direction. Is continuous. The semi-annular portion 15a is integrated with the connecting portion 15b so that the notch direction of the opening 15f (that is, the direction in which the semi-annular portion 15a faces) is the direction along the short direction of the connecting portion 15b. Yes. The length of the connecting portion 15b in the longitudinal direction is formed such that the opening 15f formed by the semi-annular portion 15a overlaps the shutter opening 12 when the round hole 15c is attached to the first rotating shaft 13 and rotated.

  A long hole 15d of the first shutter blade 15 is formed in the connecting portion 15b. Specifically, the long hole 15d of the first shutter blade 15 is formed along the substantially short direction of the connecting portion 15b at a portion closer to the semi-annular portion 15a than the round hole 15c. The notch 15e is formed in the semi-annular part 15a. Specifically, the notch 15e tapers outward from the inner diameter of the semi-annular portion 15a along a line segment parallel to the short direction of the connecting portion 15b passing through the center of the semi-annular portion 15a. Formed.

  The second shutter blade 16 has a semi-annular portion 16a, a connecting portion 16b, a round hole 16c, a long hole 16d, and a notch 16e. The outer shape of the second shutter blade 16 is the first. The outer shape is the same as that of the one shutter blade 15. The first shutter blade 15 is pivotally supported by the first rotary shaft 13 so that the opening 15f of the semi-annular portion 15a faces upward in FIG. The opening 16f of the annular portion 15a is rotatably supported on the second rotary shaft 14 in a posture in which the opening 16f faces downward in FIG.

  In addition to the second shutter blade 16, a blade driving lever 17 is rotatably supported on the second rotating shaft 14. The wing drive lever 17 is not fixed to the second rotating shaft 14 and is not interlocked with the second shutter wing plate 16 by the second rotating shaft 14. The wing drive lever 17 has a rotating portion 17a into which the second rotating shaft 14 is inserted, and three link portions 17b, 17c, and 17d extending in three directions around the rotating portion 17a. The first link portion 17b and the third link portion 17d are substantially opposed to each other with the rotating portion 17a as the center, and the second link portion 17c is the first link portion 17b and the third link portion 17d with the rotating portion 17a as the center. It extends in a substantially vertical direction.

  A wing drive pin 17e is erected on the first link portion 17b. With the wing drive lever 17 attached to the second rotating shaft 14, the wing drive pin 17 e is inserted into the long hole 15 d of the first shutter blade 15 and the long hole 16 d of the second shutter blade 16.

  Therefore, when the blade drive lever 17 rotates around the second rotation shaft 14, the first shutter blade plate 15 rotates around the first rotation shaft 13 and the second shutter blade plate 16 rotates around the second rotation shaft 14. , The first shutter blade 15 rotates in the reverse direction. Specifically, when the wing drive lever 17 rotates counterclockwise on the paper surface of FIG. 1, the first shutter blade plate 15 rotates clockwise on the paper surface of FIG. 1, and the second shutter blade plate 16 rotates as shown in FIG. Rotate counterclockwise on the page. As a result, an opening is formed between the first shutter blade 15 and the second shutter blade 16 on the shutter opening 12. When the wing drive lever 17 rotates clockwise in the plane of FIG. 1, the first shutter wing plate 15 rotates counterclockwise in the plane of FIG. 1, and the second shutter wing plate 16 rotates in the plane of FIG. Rotate clockwise. As a result, the first shutter blade 15 and the second shutter blade 16 overlap on the shutter opening 12, and the previous opening is closed.

  As shown in FIG. 1, the second link portion 17 c has a semi-annular portion 15 a of the first shutter blade 15 and a semi-annular portion 16 a of the second shutter blade 16 that overlap each other on the shutter opening 12. In a state where there is no contact, it comes into contact with a rotation stop pin 18 as a restricting member provided on the shutter reference plate 11. Specifically, the rotation stop pin 18 abuts on the right side surface of the second link portion 17c in FIG. Accordingly, the wing drive lever 17 cannot rotate rightward from the state in which the second link portion 17c is in contact with the rotation stop pin 18, but can rotate only leftward.

  A through hole 17f is formed at the tip of the second link portion 17c. A fixing pin 19 is formed above the rotation stopping pin 18 of the shutter reference plate 11 in FIG. Between the through hole 17f and the fixing pin 19, a closing spring 20 as an elastic member or a first elastic member is disposed. The distance between the through-hole 17 f and the fixing pin 19 in a state where the second link portion 17 c is in contact with the rotation stop pin 18 is wider than the natural length of the closing spring 20. Therefore, the closing spring 20 is stretched between the through hole 17f and the fixing pin 19 in an always extended state, and the wing drive lever 17 is also in a state where the second link portion 17c is in contact with the rotation stop pin 18. Is applied to the wing drive lever 17.

  One end of the fibrous shape memory alloy 21 is fixed to the tip of the third link portion 17d. The fibrous shape memory alloy 21 has a property of shrinking when heated to a high temperature. The fibrous shape memory alloy 21 is soft like a yarn at a low temperature (normal temperature range), but becomes hard when heated and contracted.

  FIG. 2 is a temperature shrinkage characteristic diagram showing the shrinkage characteristic of the fibrous shape memory alloy 21 shown in FIG. In this temperature shrinkage characteristic diagram, a heating shrinkage process curve and a cooling elongation process curve of the fibrous shape memory alloy 21 are shown. The horizontal axis is the temperature of the fibrous shape memory alloy 21, and the vertical axis is the shrinkage strain (%) of the fibrous shape memory alloy 21. The shrinkage strain (%) of the fibrous shape memory alloy 21 is based on the temperature of the fibrous shape memory alloy 21 being 0 degrees. When the length of the fibrous shape memory alloy 21 at 0 degrees is L, the shrinkage strain (%) is x%. The length of the fibrous shape memory alloy 21 is (100−x) × L ÷. It means that the length is 100.

  The heat shrinkage process curve is a characteristic curve showing the relationship between the temperature and the shrinkage strain rate when the fibrous shape memory alloy 21 is heated. The fibrous shape memory alloy 21 slowly contracts to a contraction strain of about 1.0% when heated from 0 degrees to about 70 degrees, and about 5.0% when heated from about 70 degrees to about 80 degrees. It contracts rapidly to a shrinkage strain of about 80% to about 100 ° C and slowly contracts to a shrinkage strain of about 6.0%.

  The cooling shrinkage process curve is a characteristic curve showing the relationship between the temperature and the shrinkage strain rate when the fibrous shape memory alloy 21 is being cooled. And when this fibrous shape memory alloy 21 is cooled from about 100 degrees to about 75 degrees, it slowly stretches from about 6.0% shrinkage strain to about 5.0% shrinkage strain, and from about 75 degrees to about 65 degrees. When it is cooled down to a degree, it stretches rapidly to a contraction strain of about 1.0%, and when it is cooled down from about 65 degrees to 0 degrees, it slowly stretches to a contraction strain of about 0%.

  Returning to FIG. 1, the other end of the fibrous shape memory alloy 21 is fixed to one end of a movable piece 22 as a releasing means or a movable member. The movable piece 22 is a linear metal member, and a through hole 22 a is formed at the other end of the movable piece 22. A third rotation shaft 23 formed in the housing so as to be parallel to the second rotation shaft 14 is inserted into the through hole 22a. The movable piece 22 is rotatably supported around the third rotation shaft 23. The movable piece 22 is arranged at a position where the fibrous shape memory alloy 21 is substantially parallel to the shutter reference plate 11.

  In the first embodiment, the movable piece 22 and the wing drive pin 17e rotate in the same plane, and the fibrous shape memory alloy 21 is arranged in a straight line between the movable piece 22 and the wing drive lever 17. Established. The movable piece 22 and the wing drive pin 17e are rotated on two rotation surfaces parallel to each other, and the fibrous shape memory alloy 21 is moved by a support mechanism such as a pulley disposed between the two rotation surfaces. It may be configured to be bent or curved. The fibrous shape memory alloy 21 may be arranged along the periphery of the lens barrel of the lens device.

  In the vicinity of one end of the movable piece 22, a holding magnet 24 as a releasing means or a holding means is disposed. The holding magnet 24 is obtained by winding a coil 24b around a U-shaped iron core 24a. In the first embodiment, the U-shaped iron core 24 a of the holding magnet 24 is disposed on the rotating surface of the movable piece 22. When the coil 24b of the holding magnet 24 is energized, the movable piece 22 is attracted to the U-shaped iron core 24a of the holding magnet 24 by a magnetic attractive force.

  A through hole 22 b is formed at the center of the movable piece 22. A fixing pin 25 is formed in the housing near the holding magnet 24. A magnet spring 26 as a second elastic member is disposed between the through hole 22b and the fixing pin 25. The distance between the through hole 22b and the fixing pin 25 in a state where the movable piece 22 is in contact with the U-shaped iron core 24a is wider than the natural length of the magnet spring 26. Therefore, the magnet spring 26 is always stretched between the through hole 22b and the fixed pin 25, and the movable piece 22 is moved even when the movable piece 22 is in contact with the U-shaped iron core 24a. A force to rotate rightward is applied to the movable piece 22.

  The force that the magnet spring 26 applies to the movable piece 22 is smaller than the force that the closing spring 20 applies to the wing drive lever 17. Therefore, the force that the magnet spring 26 applies to the movable piece 22 gives a light tensile force to the fibrous shape memory alloy 21, but the second link portion 17 c of the wing drive lever 17 is separated from the rotation stop pin 18 by that force. There is no end.

  For example, a fixed pin is provided between the U-shaped iron core 24 a of the holding magnet 24 and the movable piece 22, and the movable piece 22 comes into contact with the fixed pin when the holding magnet 24 attracts the movable piece 22. It may be configured. In this case, the natural length of the magnet spring 26 may be shorter than the distance between the through hole at the center of the movable piece 22 and the fixed pin in a state where the movable piece 22 is in contact with the fixed pin. Thus, when the fixed pin with which the movable pin abuts is provided separately from the holding magnet 24, the U-shaped iron core 24 a of the holding magnet 24 can simply apply a magnetic attractive force to the movable piece 22. Since it should just be possible, it does not need to be arranged on the rotating surface of the movable piece 22.

  Further, the length of the fibrous shape memory alloy 21 at normal temperature is formed such that the movable piece 22 contacts the holding magnet 24 even if the holding magnet 24 does not attract the movable piece 22. That is, the length of the fibrous shape memory alloy 21 is formed such that the movable piece 22 contacts the holding magnet 24 in the state where there is no opening by the first shutter blade 15 and the second shutter blade 16. Yes. Thus, the movable piece 22 always comes into contact with the holding magnet 24 when the fibrous shape memory alloy 21 is not contracted.

  FIG. 3 is a circuit configuration diagram showing an electronic circuit of the still camera according to Embodiment 1 of the present invention.

  The electronic circuit of the still camera mainly includes a battery 31, a booster circuit 32, a flash circuit 33, a shutter drive circuit 35, a microcomputer 36, and an EEPROM (Electrically Erasable Programmable Read-Only Memory) as a nonvolatile memory. 37, an ISO information reading circuit 38 indicating film sensitivity, a distance measuring circuit 39, a photometric circuit 40, and a release button 41.

  As the battery 31, for example, a storage battery such as a rechargeable battery or a primary battery is used. The negative terminal of the battery 31 is connected to the ground 42.

  The booster circuit 32 boosts the power supply voltage of the battery 31 to a predetermined voltage. The voltage generated by the booster circuit 32 is stabilized at a substantially constant voltage even if the voltage of the battery 31 decreases.

  The flash circuit 33 includes a capacitor and a discharge lamp. The flash circuit 33 charges the capacitor to a potential corresponding to the charge set signal from the microcomputer 36, and applies the charging voltage of the capacitor to the discharge lamp by the flash trigger signal. The discharge lamp is lit by application of this charging voltage. Light from the discharge lamp is emitted to the subject as flash light. The flash circuit 33 outputs the charging voltage of the capacitor as a charging signal.

  The shutter drive circuit 35 includes a magnet transistor 51, a first resistor 52, an energizing transistor 53, a second resistor 54, and a detection resistor 55.

  The magnet transistor 51 is a PNP transistor. The emitter of the magnet transistor 51 is connected to the plus terminal of the battery 31. The collector of the magnet transistor 51 is connected to one end of the coil 24 b of the holding magnet 24. The other end of the coil 24b of the holding magnet 24 is connected to a ground 42 (a grounding point to which a negative terminal of the battery 31 is connected). The base of the magnet transistor 51 is connected to one end of the first resistor 52. The other end of the first resistor 52 is connected to the microcomputer 36. That is, a series circuit of the magnet transistor 51 and the coil 24 b is connected to the battery 31.

  The energizing transistor 53 is a PNP transistor. The emitter of the energizing transistor 53 is connected to the booster circuit 32. The collector of the energizing transistor 53 is connected to one end of the fibrous shape memory alloy 21. The other end of the fibrous shape memory alloy 21 is connected to one end of the detection resistor 55. The other end of the detection resistor 55 is connected to the ground 42. The base of the energizing transistor 53 is connected to one end of the second resistor 54. The other end of the second resistor 54 is connected to the microcomputer 36. That is, a series circuit of the energizing transistor 53, the fibrous shape memory alloy 21, and the detection resistor 55 is connected to the booster circuit 32.

  The ISO information reading circuit 38 reads ISO information from a film cartridge loaded in the film apparatus. Then, the ISO information reading circuit 38 outputs the read ISO information to the microcomputer 36.

  The distance measuring circuit 39 measures the distance to the subject in the front direction of the still camera. Then, the distance measuring circuit 39 outputs the measured distance information to the subject to the microcomputer 36.

  The photometry circuit 40 measures the brightness in the front direction of the still camera. Then, the photometric circuit 40 outputs the measured brightness information to the microcomputer 36.

  The release button 41 includes a first switch 41a and a second switch 41b. The first switch 41a changes from the off state to the on state when the release button 41 is pressed halfway. The second switch 41b changes from the off state to the on state when all the release buttons 41 are pressed. One end of the first switch 41 a and one end of the second switch 41 b are connected to the ground 42. The other end of the first switch 41 a is pulled up by a pull-up resistor 43 and is connected to the microcomputer 36. The other end of the second switch 41 b is pulled up by a pull-up resistor 44 and is connected to the microcomputer 36.

  The EEPROM 37 stores a shooting setting selection table 61 and a pinhole current value 63.

  The shooting setting selection table 61 is a table having information on correspondence between shutter speed values, exposure values, and still camera aperture values. As described above, information unique to the still camera such as the shooting setting selection table 61 is stored in the EEPROM 37 separate from the microcomputer 36, so that the microcomputer 36 and the electronic Without changing the circuit, it is possible to cope with the change simply by replacing or rewriting the EEPROM 37. Note that the EEPROM 37 may be one in which information unique to the still camera is written in advance, or the microcomputer 36 may write information unique to the still camera.

  The pinhole current value 63 is a current value that flows through the fibrous shape memory alloy 21 when an opening begins to be formed between the first shutter blade 15 and the second shutter blade 16. When the fibrous shape memory alloy 21 is heated, the resistance value monotonously decreases as the temperature rises due to the heating, as illustrated in the current waveform in the period from tp to tF in FIG. Indicates. That is, the heating temperature of the fibrous shape memory alloy 21 and the resistance value of the fibrous shape memory alloy 21 have a one-to-one correspondence. Therefore, the value of the current flowing through the fibrous shape memory alloy 21 during energization has a one-to-one correspondence with the length of the fibrous shape memory alloy 21. The pinhole current value 63 is a current value that flows through the fibrous shape memory alloy 21 at a timing tp in FIG. 6 to be described later. In the still camera according to the first embodiment, the first shutter at the timing tp. An opening begins to be formed between the blade 15 and the second shutter blade 16.

  The microcomputer 36 includes a nonvolatile memory 36a, a central processing unit (CPU: Central Processing Unit) 36b, and an AD converter 36c as a detector. The AD converter 36c converts an input analog voltage into a digital value. The other end of the detection resistor 55 is connected to the AD converter 36c. A still camera control program 62 is stored in the memory 36a. The central processing unit 36b reads and executes the still camera control program 62 from the memory 36a. Thereby, the microcomputer 36 implements a camera control unit 71 (see FIG. 4) as control means. The still camera control program 62 is stored in advance at the time of shipment, but may be stored in the memory 36a of the microcomputer 36 via a recording medium such as a CD-ROM or a transmission medium such as a communication line. Good.

  FIG. 4 is a block diagram showing an example of the camera control unit 71 implemented by the electronic circuit of the still camera of FIG. 3 and its peripheral circuits. The camera control unit 71 includes an exposure setting unit 72, a timing control unit 73, an energization transistor control unit 74, a magnet control unit 75, a flash control unit 76, and a pinhole detection unit 77.

  The energizing transistor control unit 74 includes an inversion buffer 81. The output of the inverting buffer 81 is connected to the other end of the second resistor 54.

  The magnet controller 75 has an inversion buffer 91. The output of the inverting buffer 91 is connected to the other end of the first resistor 52.

  The pinhole detection unit 77 includes a multiplier 111, a conductance register 112, a register 113, and a comparator 114. The pinhole current value 63 is stored in the register 113 by the exposure setting unit 72. The conductance register 112 stores the reciprocal of the resistance value of the detection resistor 55. The multiplier 111 multiplies the digital value of the AD converter 36c by the value of the conductance register 112. The comparator 114 outputs a high level when the value of the non-inverting input is larger than the value of the inverting input, and outputs a low level when not larger. The output of the multiplier 111 is input to the non-inverting input of the comparator 114, and the current value stored in the register 113 is input to the inverting input of the comparator 114.

  The flash controller 76 outputs a charge set signal to the flash circuit 33 based on the setting signal from the exposure setting unit 72. Further, the flash control unit 76 detects the charging signal and confirms whether or not the charging voltage of the capacitor is a predetermined voltage. Further, the flash control unit 76 acquires the opening amount at each time point based on the value of the current flowing through the fibrous shape memory alloy 21, and outputs a flash trigger signal to the flash circuit 33 when the opening amount is a desired amount. Output.

  The timing control unit 73 includes a register 101, a timer 102, a comparator 103, a first AND circuit 104, a second AND circuit 105, and an inverting circuit 106.

  The inverting circuit 106 inverts the input level and outputs it. The other end of the second switch 41b is connected to the input of the inverting circuit 106.

  When the count start signal is input, the timer 102 starts measuring time. The output of the comparator 114 is input to the timer 102 as a count start signal. In addition, the count value (initial value) of the timer 102 before this time measurement is zero.

  The register 101 stores an exposure time corresponding to a period during which the shutter is open, which is determined according to the exposure amount obtained based on the shutter speed. The comparator 103 outputs a high level when the value of the non-inverting input is larger than the value of the inverting input, and outputs a low level when not larger. The value stored in the register 101 is input to the non-inverting input of the comparator 103, and the measurement time of the timer 102 is input to the inverting input of the comparator 103.

  The first AND circuit 104 outputs a high level only during a period in which both two inputs are at a high level. The output of the comparator 103 is input to one of the two inputs of the first AND circuit 104, and the output of the inverting circuit 106 is connected to the other of the two inputs of the first AND circuit 104. The The output of the first AND circuit 104 is connected to the input of the inverting buffer 81.

  The second AND circuit 105 outputs a high level only during a period in which the two inputs are both at a high level. The output of the comparator 103 is input to one of the two inputs of the second AND circuit 105, and the output of the inverting circuit 106 is connected to the other of the two inputs of the second AND circuit 105. The The output of the second AND circuit 105 is connected to the input of the inverting buffer 91.

  The other end of the first switch 41a of the release button 41 is connected to the exposure setting unit 72. The exposure setting unit 72 receives brightness information of the photometry circuit 40, ISO information of the ISO information reading circuit 38, distance information of the distance measurement circuit 39, and a photographing setting selection table 61. The exposure setting unit 72 outputs a setting signal to the flash control unit 76 and sets the shutter speed in the register 101.

  Next, the operation of the still camera according to the first embodiment will be described.

  In a state where the release button 41 is not pressed, the first switch 41a and the second switch 41b are in an off state. When the second switch 41b is in the OFF state, the inverting circuit 106 outputs a low level, and the first AND circuit 104 and the second AND circuit 105 also output a low level. Therefore, the inversion buffer 81 of the energization transistor control unit 74 outputs a high level, and the energization transistor 53 is in an off state. Similarly, the inversion buffer 91 of the magnet control unit 75 outputs a high level, and the magnet transistor 51 is in an off state.

  When the magnet transistor 51 is in the off state, the holding magnet 24 does not exhibit a magnetic attractive force. Therefore, the movable piece 22 is in a state where it can freely rotate around the third rotation shaft 23. However, the movable piece 22 is held in the vicinity of or in contact with the U-shaped iron core 24 a of the holding magnet 24 by the force of the magnet spring 26. Further, a light tensile force is applied to the fibrous shape memory alloy 21 by the force of the magnet spring 26, and there is no deflection.

  When the energizing transistor 53 is turned off together with the magnet transistor 51, the second link portion 17 c of the wing drive lever 17 is in contact with the rotation stop pin 18 by the force of the closing spring 20. In a state where the second link portion 17 c is in contact with the rotation stop pin 18, the semi-annular portion 15 a of the first shutter blade 15 and the semi-annular portion 15 a of the second shutter blade 16 are connected to the shutter opening 12. Overlap on top. Thereby, the light incident on the lens device is blocked by the first shutter blade 15 and the second shutter blade 16, and the film is not exposed. Even if the temperature of the fibrous shape memory alloy 21 is slightly increased by the environmental temperature, no opening is formed between the first shutter blade 15 and the second shutter blade 16. As a result, inadvertent exposure can be prevented.

  The user of the still camera holds the still camera in a posture with the optical axis direction of the lens facing the subject, and presses the release button 41 in that state.

  When the release button 41 is pressed, first, the first switch 41a is turned on. When the first switch 41 a is turned on, the exposure setting unit 72 calculates an exposure value based on the brightness information of the photometry circuit 40 and the ISO information of the ISO information reading circuit 38. Further, the exposure setting unit 72 selects a shutter speed corresponding to the calculated exposure value and camera aperture value from the shooting setting selection table 61. If the lens device requires automatic focusing, control may be performed based on the distance information of the distance measuring circuit 39 after the first switch 41a is turned on.

  The exposure setting unit 72 sets the selected shutter speed in the register 101, and further outputs a setting signal to the flash control unit 76 when flash emission is required. When the selected shutter speed is set in the register 101, the comparator 103 outputs a high level. Further, the flash control unit 76 outputs a charge set signal to the flash circuit 33 based on the setting signal from the exposure setting unit 72, and then whether or not the charging voltage of the capacitor is a desired voltage based on the charging signal. To check. When the charging voltage of the capacitor does not reach a desired voltage, the flash control unit 76 may perform a warning sound or a warning display, for example.

  When the release button 41 is further pressed and the second switch 41b is turned on, the output of the inverting circuit 106 is changed to a high level. Therefore, both the output of the first AND circuit 104 and the output of the second AND circuit 105 change from the low level to the high level. At this time, since the comparator 103 outputs a high level, when the output of the second AND circuit 105 becomes a high level, the inverting buffer 91 outputs a low level and the magnet transistor 51 is turned on. When the magnet transistor 51 is turned on, a current flows through the coil 24 b of the holding magnet 24, and the movable piece 22 is applied to the U-shaped iron core 24 a of the holding magnet 24 by a magnetic attraction generated by the current. Adsorbed and held. FIG. 5 is a view showing a state in which the movable piece 22 is attracted and held by the holding magnet 24 in the shutter mechanism 1 of FIG. Since the fibrous shape memory alloy 21 hardly shrinks at normal temperature, the movable piece 22 is originally in contact with the holding magnet 24 by the force of the magnet spring 26 as shown in FIG. Therefore, even if the holding magnet 24 is energized, each component of the shutter mechanism 1 does not move.

  Further, when the output of the first AND circuit 104 becomes high level, the comparator 103 outputs high level, so that the inverting buffer 81 outputs low level, and the energizing transistor 53 is turned on. When the energizing transistor 53 is turned on, a current flows from the booster circuit 32 to the fibrous shape memory alloy 21 through the energizing transistor 53.

  The fibrous shape memory alloy 21 generates Joule heat when energized, and the temperature rises due to the heat generation.

  FIG. 6 is a characteristic diagram showing the relationship between the waveform of the current flowing through the fibrous shape memory alloy 21 and the shutter opening state. The horizontal axis is time, and the vertical axis is current value or opening amount. Time tON is a timing at which the second switch 41b is turned on and a current starts to flow through the fibrous shape memory alloy 21.

  The fibrous shape memory alloy 21 starts to shrink due to a temperature rise caused by energization of the fibrous shape memory alloy 21. The other end of the fibrous shape memory alloy 21 is fixed together with the movable piece 22 by a holding magnet 24. Therefore, when the fibrous shape memory alloy 21 contracts, the third link portion 17d of the wing drive lever 17 is pulled, and the wing drive lever 17 rotates to the right. FIG. 7 is a view showing a state in which the wing drive lever 17 is rotated a certain amount to the right as the fibrous shape memory alloy 21 contracts in the shutter mechanism 1 of FIG. Then, when the blade drive lever 17 rotates to the right, the first shutter blade 15 rotates to the left, and the second shutter blade 16 rotates to the right.

  By the way, the pinhole detection unit 77 monitors whether or not the opening is formed in a pinhole shape based on the energization current value of the fibrous shape memory alloy 21, and sends the timer 102 to the timer 102 when the opening is formed. Is set to high level. Thereby, the timer 102 starts measuring time.

  When the fibrous shape memory alloy 21 is further contracted, the semi-annular portion 15a of the first shutter blade 15 and the semi-annular portion 15a of the second shutter blade 16 are separated from the shutter opening portion 12, and the shutter opening portion. The entire area of 12 is exposed. FIG. 8 is a view showing a state where the shutter is fully opened in the shutter mechanism 1 of FIG. This timing is tF in FIG.

  Thus, the fibrous shape memory alloy 21 shrinks as the elapsed time from the start of energization becomes longer, and as shown in FIG. 6, the first shutter blade 15 and the second shutter blade 16 The opening formed at the top will also grow.

  Note that the flash circuit 33 emits flash light when the detected current becomes a current when the opening amount becomes a desired magnitude.

  Thereafter, when the measurement time of the timer 102 becomes longer than the exposure time stored in the register 101, the comparator 103 changes its output to a low level. When the output of the comparator 103 changes to low level, the output of the second AND circuit 105 changes to low level, and the output of the inverting buffer 91 changes to high level. When the output of the inverting buffer 91 becomes a high level, the magnet transistor 51 changes to an off state, and energization to the coil 24b of the holding magnet 24 is stopped. This timing is tOFF timing in FIG. When the energization of the coil 24b is stopped, the holding magnet 24 does not exert a magnetic attractive force, so that the movable piece 22 rotates due to an imbalance between the restoring force of the closing spring 20 and the restoring force of the magnet spring 26. To do. That is, since the force of the closing spring 20 is larger than the force of the magnet spring 26, the movable piece 22 is separated from the holding magnet 24, and the wing drive lever 17 has the second link portion 17c of the wing drive lever 17 as a rotation stop pin. Rotate clockwise until it contacts 18. FIG. 9 is a diagram showing a state immediately after the energization of the coil 24b is stopped in the shutter mechanism 1 of FIG. Accordingly, the first shutter blade 15 rotates to the right, the second shutter blade 16 rotates to the left, and the first shutter blade 15 and the second shutter blade 16 cover the shutter opening 12. Thereby, the shutter is closed.

  On the other hand, when the output of the comparator 103 changes to low level, the output of the first AND circuit 104 changes to low level, and the output of the inverting buffer 81 changes to high level. When the output of the inversion buffer 81 becomes high level, the energization transistor 53 changes to an off state, and energization to the fibrous shape memory alloy 21 is stopped. When energization of the fibrous shape memory alloy 21 is stopped, the fibrous shape memory alloy 21 begins to cool naturally. Immediately after the energization is stopped, the fibrous shape memory alloy 21 is in a contracted state. Therefore, as shown in FIG. 9, immediately after the energization is stopped, the movable piece 22 is in a state of being separated from the iron core 24 a of the holding magnet 24.

  Thereafter, when the natural cooling of the fibrous shape memory alloy 21 proceeds, the fibrous shape memory alloy 21 gradually expands and returns to its original length, and the movable piece 22 is attached to the holding magnet 24 as shown in FIG. The state returns to contact with the iron core 24a. In the cooling extension process, as shown in FIG. 2, the temperature at which the extension progresses steeply may be low, and the time until it returns to the original length becomes long. The shutter is closed at high speed by opening the other end of the fibrous shape memory alloy 21 by the holding magnet 24.

  As described above, in the still camera according to the first embodiment, the fibrous shape memory alloy 21 is energized to generate heat, and the shutter device is opened and closed using the contraction caused by the energization of the fibrous shape memory alloy 21. Can do.

  According to the first embodiment, the fibrous shape memory alloy that is urged by the closing spring 20 in the direction of closing the opening between the first shutter blade 15 and the second shutter blade 16 used for the shutter and contracts when energized. The first shutter blade 15 and the second shutter blade 16 are closed against the biasing force of the spring 20 and opened by the contraction of the first shutter blade 15 and the second shutter blade 16. After opening between 15 and the second shutter blade 16, the other end of the fibrous shape memory alloy 21 is moved to release the urging force of the fibrous shape memory alloy 21. Therefore, even if it takes time to stretch the fibrous shape memory alloy 21, the opening can be controlled regardless of the stretching time by releasing the urging force of the fibrous shape memory alloy 21. Therefore, the opening of the shutter can be controlled by energizing the fibrous shape memory alloy 21 with a simple configuration.

  Further, according to the first embodiment, when the fibrous shape memory alloy 21 is not energized, the movable piece 22 is brought into a predetermined holding position by the holding magnet 24 while the wing drive lever 17 is in contact with the rotation stopping pin 18. The magnet spring 26 is formed to have a length that can be held, and pulls the movable piece 22 to a predetermined position while the coil 24b of the holding magnet 24 is not energized. As a result, the movable piece 22 does not move, and chattering due to the moment of inertia of the rotor occurs, for example, when the opening is controlled by rotating a rotor such as a stepping motor or an iris motor. The blades can be driven stably.

  Moreover, according to Embodiment 1, it has AD converter 36c which detects the electric current which flows into the fibrous shape memory alloy 21 as a detection electric current, and the fibrous shape memory alloy 21 shrinks | contracts with the heat | fever accompanying electricity supply, and resistance value The first shutter blade 15 and the second shutter blade 16 are rotatably disposed until the opening disappears, and the camera control unit 71 determines the amount of opening based on the value of the detected current. The timing at which the energization to the holding magnet 24 is stopped is controlled on the basis of the timing at which the opening starts to be formed. Specifically, the camera control unit 71 measures the time from the timing when the detected current becomes the pinhole current value 63, and when the time reaches a time corresponding to a predetermined exposure amount, the camera control unit 71 supplies the holding magnet 24. Is turned off. Thereby, even if the fibrous shape memory alloy 21 contracts due to its environmental temperature, the fibrous shape memory alloy 21 can be formed such that no opening is formed. Thereby, inadvertent exposure can be prevented. In addition, since the timing for stopping energization of the holding magnet 24 is controlled on the basis of the timing when the opening starts to be formed, the period from the start of energization to the fibrous shape memory alloy 21 until the opening starts to be formed Even if fluctuates depending on the environmental temperature, the opening time and the exposure amount can be made accurate.

Embodiment 2. FIG.
In the still camera according to the second embodiment, the shutter device in the first embodiment is a program shutter device. The program shutter device according to the second embodiment has the same mechanical configuration as the shutter device according to the first embodiment, but the control method of both is different.

  FIG. 10 is a circuit configuration diagram showing an electronic circuit of a still camera according to the second embodiment. The EEPROM 37 stores an imaging setting selection table 65, a pinhole current value 63, and an FI table 64.

  The shooting setting selection table 65 is a table in which the shutter speed and the aperture value are associated with the exposure value.

The FI table 64 is a table in which a current value for energizing the fibrous shape memory alloy 21 is associated with each of a plurality of aperture values (F values). The F value is a value indicating the opening amount of the shutter. Examples of combinations of a plurality of F values include F2.8, F4, F5.6, F8, F11, and F16. When the number following F becomes smaller, the aperture value becomes closer to the open value. The FI table 64 is associated with the current value for each aperture value.
The camera control program 62a in the second embodiment is a camera control program for performing control corresponding to the program shutter.
Other configurations in FIG. 10 are the same as those in the first embodiment, and the same reference numerals are given and description thereof is omitted.

  FIG. 11 is a characteristic diagram showing the relationship between the current waveform flowing through the fibrous shape memory alloy 21 and the shutter opening state in the second embodiment. The horizontal axis is time, the left vertical axis is the current value, and the right vertical axis is the opening amount. In the still camera of the second embodiment, six aperture values from F2.8 to F16 correspond to the aperture as shown in FIG. The FI table 64 associates the six aperture values with the six current values corresponding to the respective aperture values. In the following, the respective current values are described as I2.8, I4, I5.6, I8, I11, and I16 as shown in FIG.

  FIG. 12 is a block diagram illustrating an example of a camera control unit 71A realized by an electronic circuit of a still camera according to Embodiment 2 and its peripheral circuits. The camera control unit 71A includes an exposure setting unit 72, a pinhole detection unit 77, a timing control unit 73, an energization transistor control unit 74, a magnet control unit 75, and a flash control unit 76. The exposure setting unit 72, the pinhole detection unit 77, the timing control unit 73, the magnet control unit 75, and the flash control unit 76 have the same functions as the configuration of the same name of the still camera according to the first embodiment. Therefore, the same reference numerals are given and the description thereof is omitted.

  The energizing transistor control unit 74 includes a register 82, a cycle timer 83, a comparator 84, and an inverting buffer 81. The register 82 stores the current value selected from the FI table 64 by the exposure setting unit 72. The period timer 83 activates the comparator 84 every predetermined period.

  The comparator 84 switches its output to a high level when activated, and continues to output the high level when the value of the non-inverting input is larger than the value of the inverting input. Further, when the value of the non-inverting input becomes smaller than the value of the inverting input, the comparator 84 switches the output to a low level and stops the comparison between the value of the inverting input and the value of the non-inverting input. The value stored in the register 82 is input to the non-inverting input of the comparator 84, and the output of the multiplier 111 is input to the inverting input of the comparator 84. The output of the comparator 84 is connected to the input of the inverting buffer 81.

  Next, the operation of the still camera according to the second embodiment will be described.

  The state in which the release button 41 is not pressed is the same as in the still camera of the first embodiment, and a description thereof is omitted.

  When the release button 41 is pressed and the first switch 41 a is turned on, the exposure setting unit 72 calculates an exposure value based on the brightness information of the photometry circuit 40 and the ISO information of the ISO information reading circuit 38. Further, the exposure setting unit 72 selects an aperture value and a shutter speed corresponding to the calculated exposure value from the shooting setting selection table 65. At this time, if flash emission is required, the exposure setting unit 72 calculates the aperture value with reference to the distance information of the distance measuring circuit 39 and the flash guide number. Further, the exposure setting unit 72 selects a current value corresponding to the calculated aperture value from the FI table 64.

  Then, the exposure setting unit 72 sets the selected shutter speed in the register 101, sets the selected current value in the register 82, and further outputs a setting signal to the flash control unit 76 when flash emission is required. . As a result, the flash control unit 76 outputs a charge set signal to the flash circuit 33.

  When the release button 41 is further pressed and the second switch 41b is turned on, the output of the inverting circuit 106 is changed to a high level by the camera control unit 71A, and the output of the first AND circuit 104 and the second AND circuit The output of 105 also changes to a high level. When the output of the second AND circuit 105 changes to a high level, the magnet transistor 51 is turned on by the camera control unit 71A, and the movable piece 22 is attracted and held by the U-shaped iron core 24a of the holding magnet 24. .

  Further, when the output of the first AND circuit 104 becomes high level, the energizing transistor control unit 74 starts operation. When the energizing transistor control unit 74 starts operation, the cycle timer 83 activates the energizing transistor control unit 74. As a result, the energization transistor control unit 74 operates and sets its output to a high level.

  When the output of the comparator 84 becomes high level, the output of the inverting buffer 81 becomes low level, the energizing transistor 53 is turned on, and current starts to flow through the fibrous shape memory alloy 21. Thereby, the fibrous shape memory alloy 21 starts to shrink. Since the movable piece 22 is attracted and held by the U-shaped iron core 24 a of the holding magnet 24, the fibrous shape memory alloy 21 is contracted, so that the first shutter blade 15 and the second shutter blade 16 are separated. An opening is formed between them. As in the first embodiment, the exposure time is measured from the timing tP when the opening is formed in a pinhole shape.

  FIG. 13 is a characteristic diagram showing an example of the current waveform flowing through the fibrous shape memory alloy 21 and the shutter opening state in the second embodiment. The horizontal axis is time, and the vertical axis is current value or opening amount. tON is the timing at which the second switch 41b is turned on and current starts to flow through the fibrous shape memory alloy 21. Since the current does not flow through the fibrous shape memory alloy 21 when the energizing transistor control unit 74 starts operation, the multiplier 111 outputs 0 as the current value of the fibrous shape memory alloy 21. Therefore, when the energizing transistor control unit 74 starts operation, the comparator 84 controls its output to a high level.

  When the current value of the multiplier 111 becomes larger than the value of the register 82, that is, when it becomes larger than the current value corresponding to the target aperture value, the comparator 84 switches its output to a low level. Thereby, the energization of the fibrous shape memory alloy 21 is stopped. And the fibrous shape memory alloy 21 stops contraction when the energization stops. FIG. 13 shows a case where the target aperture value is F5.6, and at time t5.6 when the current value of the multiplier 111 becomes I5.6 stored in the register 82, the fibrous shape memory alloy The energization of 21 is stopped. At this time, the opening amount of the shutter mechanism 1 is the target aperture value F5.6. Since the temperature rise of the fibrous shape memory alloy 21 stops when the energization is stopped, the fibrous shape memory alloy 21 does not shrink beyond the contraction amount when the energization is stopped.

  Thereafter, in a state where the energization to the fibrous shape memory alloy 21 is stopped, the fibrous shape memory alloy 21 dissipates heat by natural cooling, and the temperature of the fibrous shape memory alloy 21 starts to decrease and starts to expand. However, the amount of contraction of the fibrous shape memory alloy 21 hardly changes for a while after the energization is stopped (in FIG. 13, until it decreases from about 77 degrees to about 69 degrees). The size of the opening hardly changes.

  After the energization of the fibrous shape memory alloy 21 is stopped, the cycle timer 83 periodically starts the comparator 84 and forcibly switches the output of the comparator 84 to the high level. For this reason, a current periodically flows through the fibrous shape memory alloy 21. This current is detected by the AD converter 36 c and the pinhole detector 77. If the current value of the multiplier 111 is lower than the target current value, the comparator 84 continues to output a high level, and the current continues to flow through the fibrous shape memory alloy 21. On the contrary, if the current value of the multiplier 111 is higher than the target current value, the comparator 84 outputs a low level and the energization of the fibrous shape memory alloy 21 is stopped.

  That is, as shown in a of FIG. 13, when the current value when the comparator 84 is activated and the energization of the fibrous shape memory alloy 21 is almost the same as the target current value, the fibrous shape memory alloy 21. The fibrous shape memory alloy 21 is energized only for a short period for detecting the length of the current as a current value. As shown in FIG. 13b, when the current value when the comparator 84 is activated and the energization of the fibrous shape memory alloy 21 is started is lower than the target current value, the current of the fibrous shape memory alloy 21 is The fibrous shape memory alloy 21 is energized over a relatively long period until the value reaches the target current value. As shown in FIG. 13 c, when the current value when starting the energization of the fibrous shape memory alloy 21 by starting the comparator 84 is higher than the target current value, the energization of the fibrous shape memory alloy 21 is Stop immediately.

  By such energization control of the fibrous shape memory alloy 21, the length of the fibrous shape memory alloy 21 is maintained in a state where the current value when energized becomes the target current value. That is, the opening amount of the shutter mechanism 1 is maintained at the target aperture value (F5.6 in FIG. 13).

  When the flash operation is executed, the flash control unit 76 outputs a flash trigger signal to the flash circuit 33 when the desired aperture value is obtained as described above, and the flash circuit 33 emits light. Made.

  When the measurement time of the timer 102 becomes longer than the exposure time stored in the register 101, the comparator 103 changes its output to a low level. When the output of the comparator 103 changes to a low level, the output of the inversion buffer 91 changes to a high level, and energization of the coil 24b of the holding magnet 24 is stopped. This timing is tOFF timing in FIG. As a result, the movable piece 22 can freely rotate, and the shutter is closed by the force of the closing spring 20.

  On the other hand, when the output of the comparator 103 changes to a low level, the energizing transistor controller 74 stops its operation, and the output of the inverting buffer 81 changes to a high level. Thereby, the energization to the fibrous shape memory alloy 21 is stopped. Thereafter, when the natural cooling of the fibrous shape memory alloy 21 proceeds, the fibrous shape memory alloy 21 expands and returns to its original length, and the movable piece 22 contacts the iron core 24 a of the holding magnet 24 by the force of the magnet spring 26. Return to contact.

  By the way, in the still camera according to the second embodiment, the periodic timer 83 periodically activates the comparator 84, and the comparator 84 periodically energizes the fibrous shape memory alloy 21, whereby the fibrous shape memory alloy 21. Current value is detected, and the aperture value is controlled to a desired aperture value. Therefore, it is necessary to prevent the fibrous shape memory alloy 21 from being overcooled by this intermittent energization. Therefore, the period when the period timer 83 periodically starts the comparator 84 is such that the temperature of the fibrous shape memory alloy 21 is low under the use conditions of the still camera in which the environmental temperature of the fibrous shape memory alloy 21 is the lowest and is easily cooled. What is necessary is just to set it as the period below time until it becomes the minimum cooling temperature which can maintain the opening according to an aperture value. Such a cycle may be, for example, 5 ms or more and 20 ms or less. In particular, based on the hysteresis characteristics of the fibrous shape memory alloy 21, the fibrous shape memory alloy is made to have a period capable of maintaining a temperature that is higher than the temperature at which the elongation during cooling proceeds steeply (about 75 degrees in FIG. 2). The amount of shrinkage 21 can be kept constant, and the opening amount of the shutter can be controlled well.

  In the still camera according to the second embodiment, the comparator 84 periodically energizes the fibrous shape memory alloy 21, thereby detecting the current value of the fibrous shape memory alloy 21 and controlling the aperture value. Yes. Therefore, energization for detecting the current value of the fibrous shape memory alloy 21 is periodically generated. However, the temperature of the fibrous shape memory alloy 21 is accumulated by the periodic energization for detecting the state. Must not continue to rise. Therefore, the cyclic energization current value and / or the minimum energization time of the comparator 84 is the fibrous shape memory alloy 21 under the still camera usage conditions in which the fibrous shape memory alloy 21 has the highest environmental temperature and is difficult to be cooled. Is a value that does not greatly exceed a predetermined temperature (that is, the temperature at which the contraction at the time of heating sharply progresses, approximately 75 degrees in FIG. 2). It can be a value to be set. For example, if the comparator 84 is activated with a period of 10 ms, for example, a current value that flows during an energization time of 0.05 ms to 5 ms may be used.

  Note that, within one activation period, the comparator 84 repeats the comparison process every predetermined period. The period of the comparison processing is 0.1 ms at the beginning and every other 0.05 ms after the second time, even if it is every uniform period such as 0.1 ms within one start-up period. It may be the period.

  As described above, in the still camera according to the second embodiment, the program shutter device can be opened and closed by using the contraction caused by energization of the fibrous shape memory alloy 21.

  According to Embodiment 2, it has AD converter 36c which detects the electric current which flows into the fibrous shape memory alloy 21 as a detection current, and the fibrous shape memory alloy 21 shrinks with the heat | fever which energizes, and resistance value decreases. The camera control unit 71 determines the opening amount based on the value of the detected current, and when the opening amount reaches a desired size, the energization of the fibrous shape memory alloy 21 is stopped. Thereby, the opening amount can be controlled to a desired size, and can be used as a program shutter device. Further, the aperture amount of the diaphragm can be controlled steplessly based on the detected current, for example.

  Further, according to the second embodiment, after the camera control unit 71 stops energization of the fibrous shape memory alloy 21, the camera control unit 71 periodically applies pulsed energization to the fibrous shape memory alloy 21, and this periodic energization is performed. When the detected current is smaller than the current when the opening amount becomes a desired size, the fibrous shape memory alloy 21 is energized until the detected current becomes the current when the opening amount becomes the desired size. Thereby, the opening amount by shrinkage | contraction of the fibrous shape memory alloy 21 can be maintained at a desired magnitude | size. In particular, the camera control unit 71 periodically energizes the fibrous shape memory alloy 21 with a period shorter than the time when the fibrous shape memory alloy 21 contracts due to cooling due to the ambient temperature and the desired opening amount cannot be maintained. Therefore, before the fibrous shape memory alloy 21 starts to shrink by cooling, the fibrous shape memory alloy 21 is heated to a predetermined temperature, and the opening amount due to the shrinkage of the fibrous shape memory alloy 21 is set to a desired constant size. Can be maintained.

  Further, according to the second embodiment, the EEPROM 37 that stores a plurality of current values corresponding to the sizes of the plurality of openings is provided, and the camera control unit 71 includes the detected current value and the current value among the plurality of current values. The energization of the fibrous shape memory alloy 21 is controlled based on the comparison with the current value selected from the above. Thereby, the opening amount by shrinkage | contraction of the fibrous shape memory alloy 21 can be controlled to either of the predetermined several opening amount. Further, since a plurality of current values corresponding to a plurality of opening amounts are stored in the EEPROM 37, it is possible to easily cope with a change in the specifications of the camera by simply replacing or rewriting the EEPROM 37.

  Further, according to the second embodiment, the first shutter blade 15, the second shutter blade 16, and the resistance value are reduced while being contracted by the heat generated by energization, and the opening amount is reduced by driving these blades. A fibrous shape memory alloy 21 to be adjusted, an AD converter 36c for detecting a current flowing through the fibrous shape memory alloy 21 when energized, a current value detected by the AD converter 36c, and a current value corresponding to a desired opening amount And a camera control unit that controls a current value supplied to the fibrous shape memory alloy 21 so that the opening amount becomes a desired opening amount. Accordingly, the opening amount can be controlled without detecting the positions of the first shutter blade 15 and the second shutter blade 16 and the ambient temperature of the fibrous shape memory alloy 21. Control can be performed. Moreover, the shrinkage amount of the fibrous shape memory alloy 21 can be measured in real time by the current value at the time of energization.

Embodiment 3 FIG.
The still camera according to Embodiment 3 is obtained by applying the aperture control mechanism in Embodiment 2 to an aperture device.

  The aperture device includes an aperture mechanism 2 (see FIG. 14), an aperture drive circuit 45 (see FIG. 15), and an aperture controller. The aperture control unit is realized as a part of a camera control unit 71 described later.

  FIG. 14 is a front view showing the diaphragm mechanism 2 of the still camera according to Embodiment 3 of the present invention. The diaphragm mechanism 2 includes a diaphragm reference plate 27, a diaphragm opening 28, a first diaphragm blade 29 as a blade, a second diaphragm blade 30 as a blade, two rotary shafts 13 and 14, a blade drive lever 17, It has a rotation stop pin 18, a closing spring 20, a fibrous shape memory alloy 21 and a pin 3 for fixing the fibrous shape memory alloy 21. The aperture reference plate 27 has a function equivalent to that of the shutter reference plate 11 of FIG. 1, and the aperture opening 28 has a function equivalent to that of the shutter opening 12 of FIG. The diaphragm blade plate 29 has a function equivalent to that of the first shutter blade plate 15 of FIG. 1, and the second diaphragm blade plate 30 has a function equivalent to that of the second shutter blade plate 16 of FIG. is there. The other components of the aperture mechanism 2 are the same as those of the same name shown in FIG.

  FIG. 15 is a circuit configuration diagram showing an electronic circuit of a still camera according to the third embodiment.

  The electronic circuit of the still camera mainly includes a battery 31, a booster circuit 32, a flash circuit 33, an ISO information reading circuit 38, a distance measuring circuit 39, a photometric circuit 40, a release button 41, an aperture driving circuit 45 for an aperture device, an EEPROM 37, A microcomputer 36 is included. The battery 31, the booster circuit 32, the flash circuit 33, the ISO information reading circuit 38, the distance measuring circuit 39, the photometric circuit 40, the release button 41, the aperture driving circuit 45 of the aperture device, the EEPROM 37 and the microcomputer 36 are shown in FIG. It has the same function as the configuration of the same name, and the same reference numerals are given and description thereof is omitted.

  The aperture driving circuit 45 includes a magnet transistor 51, a first resistor 52, an energizing transistor 53, a second resistor 54, and a detection resistor 55. These components have the same functions as the components of the same name shown in FIG. 10, and the same reference numerals are given and description thereof is omitted.

  The EEPROM 37 stores a shooting setting selection table 66 and an FI table 64. The FI table 64 has the same function as the component of the same name shown in FIG. 13, and the description thereof is omitted by attaching the same reference numeral.

  The shooting setting selection table 66 is a table in which the aperture value is associated with the exposure value and the shutter speed of the still camera.

  The microcomputer 36 includes an AD converter 36c, a memory 36a, and a central processing unit 36b. A still camera control program 62 is stored in the memory 36a. These constituent elements have the same functions as the constituents of the same name shown in FIG.

  The central processing unit 36b executes the still camera control program 62B, thereby realizing the camera control unit 71B. FIG. 16 is a block diagram showing an example of a camera control unit 71B realized by the electronic circuit of the still camera shown in FIG. 15 and its peripheral circuits. The camera control unit 71B includes an exposure setting unit 72, an energization transistor control unit 74A, and a shutter control unit 201. Among these components, those having the same functions as those of the configuration having the same name shown in FIG. 12 are denoted by the same reference numerals and description thereof is omitted.

  The energizing transistor control unit 74A includes a register 82, a cycle timer 83, a comparator 84, an inverting buffer 81, a conductance register 85, and a multiplier 86. The conductance register 85 stores the reciprocal of the resistance value of the detection resistor 55. The multiplier 86 multiplies the output of the AD converter 36c by the value of the conductance register 85. The comparator 84 compares the value of the register 82 with the output of the multiplier 86. The register 82, the period timer 83, the comparator 84, and the inverting buffer 81 have the same functions as the configuration of the same name shown in FIG.

The other end of the first switch 41 a of the release button 41 is connected to the exposure setting unit 72. The exposure setting unit 72 receives brightness information of the photometry circuit 40, ISO information of the ISO information reading circuit 38, distance information of the distance measurement circuit 39, a photographing setting selection table 66, and an FI table 64. Is done. The exposure setting unit 72 sets a current value corresponding to the aperture value in the register 82 of the energizing transistor control unit 74A.
The shutter control unit 201 controls a shutter device (not shown) according to an operation on the switch 41b.

  Next, the operation of the still camera according to the third embodiment will be described.

  The state where the release button 41 is not pressed is in the same state as the still camera according to Embodiment 2, and the description thereof is omitted.

  When the release button 41 is pressed and the first switch 41 a is turned on, the exposure setting unit 72 calculates an exposure value based on the brightness information of the photometry circuit 40 and the ISO information of the ISO information reading circuit 38. Further, the exposure setting unit 72 selects an aperture value corresponding to the calculated exposure value from the shooting setting selection table 66.

  When the energizing transistor control unit 74A starts operating, the cycle timer 83 activates the comparator 84, and the comparator 84 sets its output to the high level. When the output of the comparator 84 is controlled to a high level, the output of the inversion buffer 81 becomes a low level, the energizing transistor 53 is turned on, and a current begins to flow through the fibrous shape memory alloy 21. Thereby, the fibrous shape memory alloy 21 starts to shrink. As the fibrous shape memory alloy 21 contracts, the first diaphragm blade 29 and the second diaphragm blade 30 begin to rotate. As the first diaphragm blades 29 and the second diaphragm blades 30 rotate, an opening is formed between the first diaphragm blades 29 and the second diaphragm blades 30.

  When the current value of the multiplier 86 becomes larger than the value of the register 82, that is, when it becomes larger than the current value corresponding to the target aperture value, the comparator 84 switches its output to a low level. Thereby, the energization of the fibrous shape memory alloy 21 is stopped. Since the temperature rise of the fibrous shape memory alloy 21 stops when the energization is stopped, the fibrous shape memory alloy 21 does not shrink beyond the contraction amount when the energization is stopped.

  Thereafter, in a state in which the energization to the fibrous shape memory alloy 21 is stopped, the temperature of the fibrous shape memory alloy 21 is decreased by natural cooling and starts to be stretched. However, the shrinkage amount of the fibrous shape memory alloy 21 hardly changes for a while after the energization is stopped.

  The period timer 83 periodically starts the comparator 84 and forcibly switches the output of the comparator 84 to a high level. Therefore, a current periodically flows through the fibrous shape memory alloy 21, and the current flowing through the fibrous shape memory alloy 21 is detected by the AD converter 36 c, the conductance register 85, and the multiplier 86. If the current value of the multiplier 86 is lower than the target current value, the comparator 84 continues to output a high level, and the current continues to flow through the fibrous shape memory alloy 21. Conversely, if the current value of the multiplier 86 is higher than the target current value, the comparator 84 outputs a low level and the energization of the fibrous shape memory alloy 21 is stopped.

  By such energization control of the fibrous shape memory alloy 21 as in the case of the second embodiment, the fibrous shape memory alloy 21 is maintained in a state in which the current value when energized thereto becomes the target current value. It will be. Thereby, the opening amount of the aperture mechanism 2 is controlled so as to maintain the target aperture value.

  As described above, in the still camera according to the third embodiment, the diaphragm device can be opened and closed using the contraction caused by the energization of the fibrous shape memory alloy 21.

  According to Embodiment 3, it has AD converter 36c which detects the electric current which flows into the fibrous shape memory alloy 21 as a detection electric current, and the fibrous shape memory alloy 21 shrinks with the heat | fever which energizes, and resistance value decreases. The camera control unit 71 determines the opening amount based on the value of the detected current, and when the opening amount reaches a desired size, the energization of the fibrous shape memory alloy 21 is stopped. Thereby, the opening amount can be controlled to a desired size and can be used as a diaphragm device. Further, the aperture amount of the diaphragm can be controlled steplessly based on the detected current, for example.

  Further, according to the third embodiment, the camera control unit 71 periodically applies a pulsed current to the fibrous shape memory alloy 21 after the energization of the fibrous shape memory alloy 21 is stopped. When the detected current is smaller than the current when the opening amount becomes a desired size, the fibrous shape memory alloy 21 is energized until the detected current becomes the current when the opening amount becomes the desired size. Thereby, the opening amount by shrinkage | contraction of the fibrous shape memory alloy 21 can be maintained at a desired magnitude | size. In particular, the camera control unit 71 periodically energizes the fibrous shape memory alloy 21 with a period shorter than the time when the fibrous shape memory alloy 21 contracts due to cooling by the ambient temperature and the desired opening amount cannot be maintained. Therefore, before the fibrous shape memory alloy 21 starts to shrink by cooling, the fibrous shape memory alloy 21 is heated to a predetermined temperature, and the opening amount due to the shrinkage of the fibrous shape memory alloy 21 is set to a desired constant size. Can be maintained.

  Further, according to the third embodiment, the EEPROM 37 that stores a plurality of current values corresponding to the sizes of the plurality of openings is provided, and the camera control unit 71 includes the detected current value and the current value among the plurality of current values. The energization of the fibrous shape memory alloy 21 is controlled based on the comparison with the current value selected from the above. Thereby, the opening amount by shrinkage | contraction of the fibrous shape memory alloy 21 can be controlled to either of the predetermined several opening amount. Further, since a plurality of current values corresponding to a plurality of opening amounts are stored in the EEPROM 37, it is possible to easily cope with a change in the specifications of the camera by simply replacing or rewriting the EEPROM 37.

  Further, according to the third embodiment, the first diaphragm blades 29, the second diaphragm blades 30, and the contraction due to the heat caused by energization, the resistance value decreases, and these blades are driven to reduce the opening amount. A fibrous shape memory alloy 21 to be adjusted, an AD converter 36c for detecting a current flowing through the fibrous shape memory alloy 21 when energized, a current value detected by the AD converter 36c, and a current value corresponding to a desired opening amount And a camera control unit that controls a current value supplied to the fibrous shape memory alloy 21 so that the opening amount becomes a desired opening amount. Thus, the opening amount can be controlled without detecting the position of the first diaphragm blade 29 and the second diaphragm blade 30 and the ambient temperature of the fibrous shape memory alloy 21. Control can be performed. In addition, the shrinkage amount of the fibrous shape memory alloy 21 can be measured in real time by the resistance value at the time of energization.

  Each of the above embodiments is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications and changes can be made.

  For example, in each of the above embodiments, one fibrous shape memory alloy 21 is stretched between the wing drive lever 17 and the movable piece 22. In addition to this, for example, even if a plurality of fibrous shape memory alloys 21 are stretched between the wing drive lever 17 and the movable piece 22, a thin plate or tape is provided between the wing drive lever 17 and the movable piece 22. A shape memory alloy may be stretched.

  In each of the above embodiments, the fibrous shape memory alloy 21 is heated and contracted by heat generated by energization. In addition to this, for example, if it contracts by energization, the opening can be controlled by utilizing the contraction of the member.

  In each of the above embodiments, the closing spring 20 urges the blades 15, 16, 29, 30 in the direction to close the opening of the blades 15, 16, 29, 30, and the blades are contracted by the fibrous shape memory alloy 21. The plates 15, 16, 29, and 30 are closed and opened against the urging force of the spring 20, and after the blades 15, 16, 29, and 30 are opened by the fibrous shape memory alloy 21, the fibrous shape memory alloy 21 and the like are opened. The urging force by the fibrous shape memory alloy 21 is released by moving the end. In addition to this, for example, the closing spring 20 urges the blades 15, 16, 29, and 30 in the direction to open the openings of the blades 15, 16, 29, and 30, and the blades are contracted by the fibrous shape memory alloy 21. 15, 16, 29, 30 are closed against the urging force of the closing spring 20, and after closing the slats 15, 16, 29, 30 with the fibrous shape memory alloy 21, the other end of the fibrous shape memory alloy 21 is closed. May be moved to release the urging force of the fibrous shape memory alloy 21. Even in this modification, even if it takes time to stretch the fibrous shape memory alloy 21, the opening can be controlled regardless of the stretching time. Therefore, it is possible to control the opening of the shutter and the diaphragm by energizing the fibrous shape memory alloy 21 with a simple configuration.

  Each of the above embodiments is an example of controlling the opening of a still camera. In addition to this, the present invention can be applied to, for example, a digital still camera, a video camera, and other cameras.

FIG. 1 is a front view showing a shutter mechanism of a still camera according to Embodiment 1 of the present invention. FIG. 2 is a temperature shrinkage characteristic diagram showing the shrinkage characteristic of the fibrous shape memory alloy shown in FIG. FIG. 3 is a circuit configuration diagram showing an electronic circuit of the still camera according to Embodiment 1 of the present invention. FIG. 4 is a block diagram showing an example of a camera control unit realized by the electronic circuit of the still camera of FIG. 3 and its peripheral circuits. FIG. 5 is a diagram illustrating a state in which the movable piece is attracted and held by the holding magnet in the shutter mechanism of FIG. 1. FIG. 6 is a characteristic diagram showing the relationship between the current waveform flowing through the fibrous shape memory alloy and the opening state of the shutter. FIG. 7 is a view showing a state in which the wing drive lever is rotated to the right by a certain amount as the fibrous shape memory alloy contracts in the shutter mechanism of FIG. FIG. 8 is a view showing a state where the shutter is fully opened in the shutter mechanism of FIG. FIG. 9 is a diagram showing a state immediately after the energization of the coil is stopped in the shutter mechanism of FIG. FIG. 10 is a circuit configuration diagram showing an electronic circuit of a still camera according to the second embodiment. FIG. 11 is a characteristic diagram showing the relationship between the current waveform flowing through the fibrous shape memory alloy and the opening state of the shutter in the second embodiment. FIG. 12 is a block diagram illustrating an example of a camera control unit realized by an electronic circuit of a still camera according to Embodiment 2 and its peripheral circuits. FIG. 13 is a characteristic diagram showing an example of a current waveform flowing through the fibrous shape memory alloy and an opening state of the shutter according to the second embodiment. FIG. 14 is a front view showing an aperture mechanism of a still camera according to Embodiment 3 of the present invention. FIG. 15 is a circuit configuration diagram showing an electronic circuit of a still camera according to the third embodiment. FIG. 16 is a block diagram showing an example of a camera control unit realized by the electronic circuit of the still camera shown in FIG. 15 and its peripheral circuits.

Explanation of symbols

15 First shutter blade (blade)
16 Second shutter blade (blade)
18 Anti-rotation pin (regulator)
20 Closing spring (elastic member, first elastic member)
21 Energizing contraction member 22 Movable piece (release means, movable member)
24 Holding magnet (release means, holding means)
26 Magnet spring (second elastic member)
29 First diaphragm blade (blade)
30 Second diaphragm blade (blade)
33 Flash circuit 36c AD converter (detector)
37 EEPROM (non-volatile memory)
71, 71A, 71B Camera control unit (control means)

Claims (14)

At least shutter blades,
An elastic member for urging the slats in a direction to close the opening of the slats;
An energization contraction member that contracts by energization and biases and opens the wing plate against the energizing force of the elastic member by the contraction;
Release means for moving the end of the energization contraction member after the opening of the slats by the energization contraction member to release the urging force by the energization contraction member;
An opening control mechanism comprising: A slat arranged so as to be rotatable or movable, and forming an opening through which light from the lens passes by this rotation or movement;
A regulating member that comes into contact with the wing plate with the smallest opening or the wing plate with no opening,
A first elastic member for applying a force to the wing plate to bring the wing plate into contact with the regulating member;
A movable member arranged to be rotatable or movable;
Holding means for holding the movable member in a predetermined position by energization;
An electrically conductive contracting member that connects the movement of the slats and the movable member so as to be interlocked, and contracts in a direction opposite to the urging direction by the first elastic member by energization;
By energizing the holding means and the energization contracting member, the blade is rotated or moved in a direction away from the regulating member to open a predetermined amount, and then the energization to the holding means is stopped. A control means for rotating or moving the slats in a direction to be brought into contact with the regulating member by a restoring force of the first elastic member;
An opening control mechanism comprising: The energization contraction member is formed to a length that allows the movable member to be held at a predetermined position by the holding means while the wing plate is in contact with the restriction member when the energization contraction member is not energized.
3. The opening control mechanism according to claim 2, further comprising a second elastic member that pulls the movable member to the predetermined position in a state where the holding means is not energized. Having a detector that detects a current flowing through the energization contracting member as a detection current;
The energization contraction member is a shape memory alloy that contracts due to heat accompanying energization and increases or decreases in resistance value,
The slats are arranged to be rotatable or movable to a state where there is no opening,
3. The control unit according to claim 2, wherein the control unit determines an opening amount based on the value of the detection current, and controls a timing at which energization to the holding unit is stopped based on a timing at which the opening starts to be formed. Opening control mechanism.   The control means measures the time from the timing when the detected current becomes a current when the opening starts to be formed, and when the time reaches a time corresponding to a predetermined exposure amount, the control means energizes the holding means. The opening control mechanism according to claim 4, wherein the opening control mechanism is stopped. Having a detector that detects a current flowing through the energization contracting member as a detection current;
The energization contraction member is a shape memory alloy that contracts due to heat accompanying energization and increases or decreases in resistance value,
3. The opening control according to claim 2, wherein the control means determines an opening amount based on the value of the detected current, and stops the energization of the energization contracting member when the opening amount reaches a desired size. mechanism.   When the energizing / shrinking member is periodically energized to the energizing / shrinking member after the energizing / shrinking member is deenergized, the control means detects when the opening amount is a desired magnitude. 7. Any one of claims 4 to 6, wherein if the current is smaller than the current, the energizing contraction member is energized until the detected current becomes a current when the opening amount becomes a desired magnitude. The opening control mechanism according to Item.   The said control means shrinks | contracts with the cooling by ambient temperature, and the said control means performs periodic electricity supply to the said electricity contraction member with a period shorter than the time when the desired opening amount cannot be maintained. 8. The opening control mechanism according to 7. A non-volatile memory for storing a plurality of current values corresponding to the sizes of the plurality of openings;
The control means controls energization of the energization contracting member based on a comparison between the value of the detected current and a current value selected from the plurality of current values. The opening control mechanism according to any one of the above. A detector that detects a current flowing through the energization contracting member as a detection current, and a flash circuit that emits flash light;
The energization contraction member is a shape memory alloy that contracts due to heat accompanying energization and increases or decreases in resistance value,
3. The aperture control mechanism according to claim 2, wherein the control means causes the flash circuit to emit flash light when the detected current becomes a current when the aperture size becomes a desired size. At least shutter blades,
An elastic member for biasing the slats in a direction to open the opening of the slats;
An energization contraction member that contracts by energization and energizes and closes the wing plate against the energizing force of the elastic member by the contraction;
Release means for releasing an urging force by the energizing contraction member by moving an end of the energization contraction member after closing the slat by the energization contraction member;
An opening control mechanism comprising: With slats,
A shape memory alloy that contracts with heat caused by energization and increases or decreases in resistance, and drives the slats to adjust the opening amount;
A detector for detecting a current flowing in the shape memory alloy when energized;
Based on the current value detected by the detector and the current value corresponding to the desired opening amount, control means for controlling the current value to be applied to the shape memory alloy so that the opening amount becomes the desired opening amount When,
An opening control mechanism comprising: An optical system for imaging;
A light receiving unit for receiving an image obtained through the optical system;
The aperture control mechanism according to any one of claims 1 to 12, wherein exposure to the light receiving unit by light transmitted through the optical system is controlled.
An imaging apparatus comprising: Energize with an elastic member in the direction to close at least the opening of the slats for shutters,
Using an energization contraction member that contracts by energization, the wing plate is urged and opened against the urging force of the elastic member by the contraction,
After the opening of the slats by the energization contraction member, the end of the energization contraction member is moved to release the urging force by the energization contraction member;
An opening control method characterized by the above.

Images