JP2015230387A - Focal plane shutter and optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a focal plane shutter and an optical device which have occurrence of dust suppressed.SOLUTION: A focal plane shutter comprises: a base plate; a curtain; an electromagnet; a drive lever which has an iron piece to be adsorbed and held by the electromagnet, and is slidably supported to the base plate; a drive arm which is coupled to the drive lever, slidably supported to the base plate and drives the curtain; an energizing member that energizes the drive lever in such a way that the iron piece separates from the electromagnet, and causes the curtain to be travelled; a ratchet wheel 50B which engages with the energizing member to enable adjustments of the energizing force of the energizing member; and a lock member 130b which includes a pawl part 131 allowing the ratchet wheel 50B to stop at a prescribed position. The ratchet wheel 50B is composed of a tooth row part 51 having a plurality of teeth allowed to be engaged with by the pawl part 131 partially formed in an outer periphery of the ratchet wheel 50B, and a curve part 52 in which the teeth are not formed and the pawl part 131 is slidable, to suppress occurrence of dust.

Description

  The present invention relates to a focal plane shutter and an optical apparatus.

  Patent Document 1 includes an urging member that travels a curtain, a ratchet wheel for adjusting the urging force of the urging member, and a locking member that includes a claw portion that can be engaged with and stopped by the ratchet wheel. A focal plane shutter provided is disclosed. By rotating the ratchet wheel, the urging force of the urging member can be adjusted, thereby adjusting the traveling speed of the curtain.

JP 2010-44129 A

  On the outer periphery of the ratchet wheel, a tooth row portion is formed over the entire area. For this reason, when adjusting the urging force of the urging member by rotating the ratchet wheel, the claw portion slides on the dentition while being pressed against the dentition by its own elastic restoring force. Thereby, there is a possibility that the tooth row portion is scraped by the claw portion and dust is generated. If such dust adheres between an iron piece of a drive lever for driving a curtain and an electromagnet capable of attracting the iron piece, as will be described in detail later, there is a risk of affecting the magnetic force acting between them. is there. This may change the running characteristics of the curtain.

  Accordingly, an object of the present invention is to provide a focal plane shutter and an optical apparatus in which generation of dust is suppressed.

  The object is to have a substrate having an opening, a curtain that can open and close the opening, an electromagnet supported by the substrate, and an iron piece that is attracted and held by the electromagnet, and a drive that is swingably supported by the substrate. A lever, a drive arm connected to the drive lever and supported by the substrate so as to be able to swing, and driving the curtain; and the drive lever is urged so that the iron piece is separated from the electromagnet to run the curtain. An urging member; a ratchet wheel that can be engaged with the urging member to adjust the urging force of the urging member; and a locking member that includes a claw portion that can stop the ratchet wheel at a predetermined position. The ratchet wheel has a plurality of teeth that are partially formed on the outer periphery of the ratchet wheel and that can engage the claw part, and the claw part is slidable without the tooth being formed. Or facing the nail part with a gap While comprising a movable curved portion, it can be achieved by the focal plane shutter.

  The above object can also be achieved by an optical apparatus provided with the above focal plane shutter.

  According to the present invention, it is possible to provide a focal plane shutter and an optical apparatus in which generation of dust is suppressed.

FIG. 1 is a front view of the focal plane shutter of this embodiment. FIG. 2 is an explanatory diagram of the operation of the focal plane shutter. FIG. 3 is an explanatory diagram of the operation of the focal plane shutter. FIG. 4 is a cross-sectional view of the periphery of the drive lever and the electromagnet in a state where the drive lever is attracted and held by the electromagnet. FIG. 5 is a side view showing the ratchet wheel and the locking member. FIG. 6 is a view of the ratchet wheel and the locking member as seen from the axial direction of the ratchet wheel. FIG. 7 is an explanatory diagram of a ratchet wheel and a locking member according to a first modification. FIG. 8 is an explanatory diagram of a ratchet wheel according to a second modification.

  Embodiments will be described below with reference to the drawings. FIG. 1 is a front view of the focal plane shutter of this embodiment. As shown in FIG. 1, the focal plane shutter 1 includes a substrate 10, blades 21a to 24a and 21b to 24b, drive arms 31a and 31b, auxiliary arms 32a and 32b, electromagnets 70A and 70B, and the like. The substrate 10 is made of synthetic resin and has a rectangular opening 11. The blades 21a to 24a and 21b to 24b are made of synthetic resin and are thinly formed. Although the blades 21a to 24a and 21b to 24b are made of synthetic resin, they may be made of metal thin plate or fiber reinforced resin, and the drive arms 31a and 31b and the auxiliary arms 32a and 32b are made of metal thin plate. It may be made of resin.

  The four blades 21a to 24a constitute the front curtain 20A. The four blades 21b to 24b constitute the rear curtain 20B. The front curtain 20A and the rear curtain 20B open and close the opening 11. FIG. 1 shows a case where the front curtain 20A is in a superimposed state and the rear curtain 20B is in a deployed state. In the case of FIG. 1, the front curtain 20 </ b> A is retracted from the opening 11, and the rear curtain 20 </ b> B closes the opening 11. The front curtain 20A and the rear curtain 20B are movable between a closed position for closing the opening 11 and a retracted position retracted from the opening 11, respectively.

  The front curtain 20A is connected to a drive arm 31a and an auxiliary arm 32a. The rear curtain 20B is connected to the drive arm 31b and the auxiliary arm 32b. These drive arms 31a and 31b and auxiliary arms 32a and 32b are supported so as to be swingable with respect to the substrate 10, respectively.

  The substrate 10 is provided with drive levers 40A and 40B for driving the drive arms 31a and 31b, respectively. The drive levers 40A and 40B are supported by the substrate 10 so as to be able to swing within a predetermined range. Specifically, the drive lever 40 </ b> A is supported so as to be swingable about an axis formed on the substrate 10. The same applies to the drive lever 40B. The drive levers 40A and 40B are drive members that drive the front curtain 20A and the rear curtain 20B, respectively. The drive levers 40A and 40B are made of synthetic resin.

  The drive arm 31a is connected to the drive lever 40A. The drive arm 31b is connected to the drive lever 40B. When the drive lever 40A swings, the drive arm 31a swings, and thereby the front curtain 20A moves. Similarly, when drive lever 40B swings, drive arm 31b swings, and rear curtain 20B moves.

  Specifically, drive pins 43a and 43b are provided on the drive levers 40A and 40B, respectively, and the drive pins 43a and 43b are fitted to the drive arms 31a and 31b, respectively. The substrate 10 is formed with escape holes 13a and 13b in an arc shape for allowing the drive pins 43a and 43b to escape, respectively. Rubbers Ga and Gb for buffering the drive pins 43a and 43b are provided at respective end portions of the escape holes 13a and 13b.

  The drive levers 40A and 40B hold iron pieces although not denoted by reference numerals. The drive lever 40A can swing between a position where the iron piece contacts the electromagnet 70A and a position where the iron piece is separated from the electromagnet 70A. In other words, the drive lever 40A is movable so that the iron piece is separated from the electromagnet 70A. The same applies to the drive lever 40B.

  The drive lever 40A is biased in a direction in which the iron piece is separated from the electromagnet 70A by a spring (not shown). Similarly, the drive lever 40B is urged in a direction in which the iron piece is separated from the electromagnet 70B by a spring (not shown). In FIG. 4 to be described later, an iron piece and a spring of the drive lever 40B are shown.

  The ratchet wheels 50A and 50B are engaged with the drive levers 40A and 40B via the springs described above. One end of a spring that urges the drive lever 40A away from the electromagnet 70A is engaged with the ratchet wheel 50A, and the other end of the spring is engaged with the drive lever 40A. The biasing force of the spring can be adjusted by adjusting the amount of rotation of the ratchet wheel 50A from an arbitrary reference position. For example, the urging force of the spring increases as the amount of rotation increases. The ratchet wheel 50B also has the same function as the ratchet wheel 50A.

  When the electromagnet 70A is energized, the iron piece of the drive lever 40A can be attracted against the biasing force of the spring described above. Similarly, when the electromagnet 70B is energized, the iron piece of the drive lever 40B can be attracted against the spring biasing force described above.

  Next, the operation of the focal plane shutter 1 will be described. 1 to 3 are explanatory diagrams of the operation of the focal plane shutter 1. Here, FIG. 2 shows an initial state of the focal plane shutter 1. In this initial state, a set lever (not shown) is fixed at the initial position, the front curtain 20A expands to close the opening 11, and the rear curtain 20B overlaps and retracts from the opening 11. In this initial state, the iron pieces of the drive levers 40A and 40B are in contact with the electromagnets 70A and 70B, respectively, and are set at initial positions where they can be attracted thereto.

  When the release button of the camera is pressed during shooting, the coils of the electromagnets 70A and 70B are energized, the iron piece of the drive lever 40A is attracted to the electromagnet 70A, and the iron piece of the drive lever 40B is attracted to the electromagnet 70B. Thereafter, the set lever is retracted from the drive levers 40A and 40B. Here, the drive levers 40A and 40B are held while being attracted to the electromagnets 70A and 70B, respectively.

  Thereafter, when the energization of the coil of the electromagnet 70A is interrupted, as shown in FIG. 3, the drive lever 40A rotates clockwise according to the biasing force of the spring, and then the rubber Ga formed at the end of the escape hole 13a Stops in contact. As a result, the front curtain 20A is retracted from the opening 11 and is in a superimposed state. Further, energization of the coil of the electromagnet 70B is maintained for a predetermined period, and the trailing curtain 20B is maintained in a state of being retracted from the opening 11. Thereby, the opening 11 will be in the open state. FIG. 3 shows a state during exposure.

  Energization of the coil of the electromagnet 70B is interrupted after a lapse of a predetermined period from the time when the release button is pressed, and the drive lever 40B rotates clockwise by the biasing force of the spring. As a result, the rear curtain 20B expands and closes the opening 11. The drive lever 40B comes into contact with the rubber Gb formed at the end of the escape hole 13b formed in the substrate 10 and stops. FIG. 1 shows a state immediately after the exposure operation is finished. In this way, one shooting is completed.

  Next, the drive levers 40A and 40B are rotated counterclockwise by a set lever (not shown). As a result, the front curtain 20A is expanded to close the opening 11, and the rear curtain 20B is overlapped and retracted from the opening 11 to return to the initial state shown in FIG.

  Next, the electromagnet 70B will be described in detail. FIG. 4 is a cross-sectional view around the drive lever 40B and the electromagnet 70B in a state where the drive lever 40B is attracted and held by the electromagnet 70B.

  The drive lever 40B includes a plate-like base portion 41b, a cylindrical portion 41b1 standing on the base portion 41b, a drive pin 43b, a holding portion 42b for holding the iron piece 46b, and the like. Around the cylindrical portion 41b1, a ratchet wheel 50B, a spring 59B that applies a biasing force to the drive lever 40B, and the like are arranged. One end of the spring 59B is fixed to the drive lever 40B side, and the other end of the spring 59B is fixed to the ratchet wheel 50B side. By adjusting the rotation amount of the ratchet wheel 50B, the urging force of the spring 59B can be adjusted. The spring 59B biases the drive lever 40B in a direction away from the electromagnet 70B.

  A support shaft 11b1 provided on the substrate 10 is fitted in the cylindrical portion 41b1. The drive lever 40B rotates in a predetermined range around the support shaft 11b1. A holding plate 120 is fixed to the tip of the support shaft 11b1 by a pin 110. A printed circuit board 100 is fixed to the upper surface side of the holding plate 120. The holding plate 120 holds the electromagnets 70A and 70B. The printed circuit board 100 controls energization to the electromagnets 70A and 70B.

  The drive pin 43b extends downward from the base portion 41b. The drive pin 43b is fitted to the drive arm 31b. A support shaft 11b2 that is substantially coaxial with the support shaft 11b1 is formed on the substrate 10. The drive arm 31b is rotatably fitted to the support shaft 11b2. The drive arm 31b rotates within a predetermined range with the support shaft 11b2 as a fulcrum.

  The holding part 42b has a wall shape standing upward from the base part 41b. A pin 45b fitted to the iron piece 46b passes through the holding portion 42b. The pin 45b penetrates the holding portion 42b so as to be movable within a predetermined range in the axial direction of the pin 45b. Between the holding part 42b and the iron piece 46b, a spring 47b is arranged to urge the both so that they are separated from each other. The spring 47b has a function of absorbing an impact when the iron piece 46b comes into contact with an iron core 76b of an electromagnet 70B described later.

  The back plate 18 faces the substrate 10. A drive arm 32b, a rear curtain 20B, and the like are accommodated between the substrate 10 and the back plate 18. The back plate 18 is formed with an escape hole 18b8 for allowing the drive pin 43b to escape and an escape hole 18b2 for allowing the support shaft 11b2 to escape.

  The electromagnet 70B includes an iron core 76b, a coil 79b for exciting the iron core 76b, and a bobbin 72b around which the coil 79b is wound. When the coil 79b is energized, a magnetic attractive force is generated between the iron core 76b and the iron piece 46b. The iron core 76b is formed in a U shape. The end surface of the front end portion of the iron core 76b is attracted to the iron piece 46b. The coil 79b is electrically connected to a pattern formed on the printed circuit board 100 by solder. Thereby, the electromagnet 70B and the printed circuit board 100 are electrically connected.

  The holding plate 120 includes a flat plate portion 121 and a pair of sandwiching portions 122 b and 125 b rising from the flat plate portion 121. The holding plate 120 is a metal thin plate that can be elastically deformed. The printed circuit board 100 is fixed to the flat plate portion 121. The sandwiching portions 122b and 125b rise from the flat plate portion 121 so as to protrude toward the substrate 10 side. The clamping portions 122b and 125b hold the electromagnet 70B.

  FIG. 4 shows a locking member 130b that engages with the ratchet wheel 50B to stop the rotation of the ratchet wheel 50B. The locking member 130b is formed integrally with the holding plate 120. The locking member 130b is a leaf spring, and the ratchet wheel 50B is stopped at a predetermined position by engaging the teeth of the tooth row portion formed on the outer periphery of the ratchet wheel 50B with the tip of the locking member 130b. The Note that the ratchet wheel 50B is rotatably supported on the tip end side of the support shaft 11b1.

  The biasing force of the spring 59B is adjusted according to the stop position of the ratchet wheel 50B. The spring 59B always urges the drive lever 40B and causes the trailing blade 20B to travel. As described above, the ratchet wheel 50B is stopped at a predetermined position by engaging the teeth of the tooth row portion of the ratchet wheel 50B with the locking member 130b. Therefore, the position where the ratchet wheel 50B can be stopped depends on the tooth pitch of the tooth row portion of the ratchet wheel 50B. The same applies to the spring 59A for running the front curtain 20A, whose urging force is adjusted by the ratchet wheel 50A. The spring 59B is an example of an urging member.

  FIG. 5 is a side view showing the ratchet wheel 50B and the locking member 130b. As will be described in detail later, FIG. 5 shows a jig 80 for adjusting the stop position of the ratchet wheel 50B. As shown in FIG. 5, a tooth row portion 51 and a curved surface portion 52 are formed on the upper stage of the outer periphery of the ratchet wheel 50B, and a tooth row portion 53 is formed on the lower stage. A plurality of teeth are formed in the tooth row portions 51 and 53. Such a tooth is not formed on the curved surface portion 52 and is a smooth curved surface. The tooth row portion 51 and the curved surface portion 52 are formed at the same height in the axial direction of the ratchet wheel 50B. The teeth of the tooth row portion 51 are engaged with the claw portion 131 of the locking member 130b, whereby the ratchet wheel 50B is stopped at a predetermined position. The tooth row portion 53 is formed over the entire outer periphery of the lower stage of the ratchet wheel 50B. A plurality of slits 58 extending in the axial direction of the ratchet wheel 50 </ b> B are formed in the tooth row portion 53. One end of the spring 59B is inserted into one of the plurality of slits 58, whereby the ratchet wheel 50B is engaged with the spring 59B.

  The tooth row portion 53 meshes with the gear 83 of the jig 80 without engaging with the locking member 130b. The jig 80 is not provided on the focal plane shutter 1, but is used when adjusting the stop position of the ratchet wheel 50B. The jig 80 includes a shaft 81 and a gear 83 fixed to the shaft 81. When the operator rotates the jig 80, the gear 83 and the tooth row portion 53 are engaged with each other, and the ratchet wheel 50B can be rotated. The tooth row portion 53 is an example of a meshing portion.

  FIG. 6 is a view of the ratchet wheel 50B and the locking member 130b as viewed from the axial direction of the ratchet wheel 50B. In FIG. 6, the tooth row portion 53 formed on the lower side of the ratchet wheel 50B is not shown. The radius R2 of the curved surface portion 52 is the same as the root radius R1 of the dentition portion 51. The tip of the claw portion 131 is located between adjacent teeth of the dentition portion 51. Specifically, the tip surface of the claw portion 131 is in contact with the side surface of the teeth of the dentition portion 51. Since the claw portion 131 is engaged with the dentition portion 51 in this way, the claw portion 131 and the teeth of the dentition portion 51 are not affected unless a large force is applied to rotate the ratchet wheel 50B in a predetermined direction. Engagement is maintained and the ratchet wheel 50B is kept stopped.

  Here, the claw portion 131 of the locking member 130 b is inclined with respect to the normal direction of the pitch circle of the tooth row portion 51. For this reason, rotation in one direction of the ratchet wheel 50B is allowed, but rotation in the opposite direction is restricted. For example, when the ratchet wheel 50B shown in FIG. 6 is rotated counterclockwise with the claw portion 131 engaged with the tooth row portion 51 using the jig 80 described above, the teeth move to the left side and the tip of the claw portion 131 is moved. As a result, a bending stress is applied in the left direction, and the claw 131 is elastically deformed. As a result, the tip of the claw portion 131 slides on the surface of the dentition portion 51 and the tip of the claw portion 131 leaves the dentition portion 51, so that the ratchet wheel 50B is allowed to rotate counterclockwise. On the other hand, when the ratchet wheel 50 </ b> B is rotated in the clockwise direction, a compressive force is applied in the length direction from the side surface of the tooth of the tooth row portion 51 to the tip of the claw portion 131. In this case, since the claw portion 131 does not easily expand and contract in the length direction, the engagement between the claw portion 131 and the dentition portion 51 is maintained without the tip of the claw portion 131 sliding the teeth of the dentition portion 51, and the ratchet. The clockwise rotation of the car 50B is restricted.

  Further, after the ratchet wheel 50 </ b> B is rotated and the claw portion 131 leaves the range where the tooth row portion 51 is formed, the claw portion 131 slides on the surface of the curved surface portion 52. Here, when the claw portion 131 is in contact with the curved surface portion 52, the curved surface portion 52 is formed into a smooth curved surface, and therefore the rotation of the ratchet wheel 50B cannot be stopped. Therefore, the operator can use the jig 80 to adjust the stop position of the ratchet wheel 50 </ b> B at a position within a range where the claw portion 131 engages with the tooth row portion 51. Thereby, the urging force of the spring 59B can be adjusted, and the operator can adjust the traveling speed of the trailing curtain 20B to a desired speed. In this embodiment, the ratchet wheel 50B is rotated so that the claw 131 slides on the curved surface portion 52 from the state before adjustment, and the claw portion 131 is rotated until the claw portion 131 is engaged with the dentition portion 51.

  As described above, while the ratchet wheel 50B is rotated and the claw portion 131 slides on the surface of the dentition portion 51, the elastic restoring force of the claw portion 131 acts on the surface of the dentition portion 51. That is, it is necessary to rotate the ratchet wheel 50B against the elastic restoring force of the claw 131. For this reason, the nail | claw part 131 may scrape the surface of the dentition part 51, and there exists a possibility that dust may generate | occur | produce. In particular, the ratchet wheel 50B is made of synthetic resin from the viewpoint of cost reduction, and the locking member 130b is a metal leaf spring. For example, when such dust adheres between the iron core 76b of the electromagnet 70B and the iron piece 46b of the drive lever 40B, the timing at which the iron piece 46b moves away from the iron core 76b is affected, and the running characteristics of the trailing curtain 20B are affected. May also have an impact.

  For example, if dust adheres between the iron core 76b of the electromagnet 70B and the iron piece 46b of the drive lever 40B, the area in which the iron core 76b and the iron piece 46b are in direct contact with each other decreases, so that the attractive force decreases. When the attraction force is reduced, the timing from when the current to the coil 79b of the electromagnet 70b is cut off until the iron core 76b and the iron piece 46b are actually separated from each other is advanced. Specifically, after the release button is pressed, the timing when the trailing curtain 20B expands and the opening 11 is closed is advanced. As a result, the exposure time may be shortened. Furthermore, when a large amount of dust adheres, the iron core 76b and the iron piece 46b may not be adsorbed.

  However, in the ratchet wheel 50B, teeth are not formed over the entire outer periphery, the tooth row portion 51 is partially provided, and the curved portion 52 is formed in the other portions. The radius R2 of the curved surface portion 52 is the same as the root radius R1 of the dentition portion 51. Accordingly, the amount of elastic deformation of the claw portion 131 is smaller than when the tip of the claw portion 131 slides on the surface of the dentition portion 51. For this reason, the force with which the nail | claw part 131 contacts the curved surface part 52 becomes small. Therefore, when the claw portion 131 slides on the curved surface portion 52, generation of dust is suppressed. Therefore, compared with the ratchet wheel having teeth formed over the entire outer periphery, the ratchet wheel 50B has a reduced number of teeth cut by the claw portion 131, and the generation of dust is suppressed.

  The dentition portion 51 is rotated until a desired urging force is obtained. If the desired urging force is constant, and if there is no performance variation between individual springs, the stopping position is also substantially constant. Position. Therefore, the dentition portion provided at a position other than the position where the desired urging force is obtained is unnecessary because it does not contribute to the adjustment.

  However, the tooth row portion 51 is formed over a certain angle range in consideration of the variation between individual differences such as the spring 59B at the desired stop position of the ratchet wheel 50B after adjustment. For example, it is formed in an angle range of 180 degrees or less on the outer periphery of the ratchet wheel 50B, and the curved surface portion 52 is formed over an angle range of 180 degrees or more. In addition, generation | occurrence | production of refuse is suppressed, so that the angle range of the dentition part 51 is small. For this reason, for example, the angle range of the dentition 51 is preferably 90 degrees or less, and more preferably 60 degrees or less. In addition, since the ratchet wheel 50B cannot be stably stopped in a state where the claw portion 131 and the curved surface portion 52 are in contact with each other, the range of the position where the ratchet wheel 50B can be stopped is larger when the angular range of the tooth row portion 51 is larger. Becomes larger. As described above, it is desirable that the angle range in which the dentition portion 51 is formed is set so as to achieve both tolerance of variation between individual differences and suppression of dust that may be generated. In the example of FIG. 6, the angle range of the curved surface portion 52 is larger than that of the dentition portion 51, and specifically, the angle range of the dentition portion 51 is set to 60 degrees. The ratchet wheel 50A is formed in the same manner as the ratchet wheel 50B.

  Since the spring 59B varies among lots of products, the urging force may be different even when the ratchet wheel 50B is adjusted to the same position. Further, depending on the required curtain speed, a greater biasing force may be required. In such a case, if the angular range in which the dentition portion 51 is formed is small, there is a possibility that it cannot be handled.

  In this embodiment, a plurality of slits 58 extending in the axial direction of the ratchet wheel 50B are formed, and the initial biasing force is changed by the slit into which one end of the spring 59B is inserted. That is, the initial urging force differs between when the spring 59B is inserted into a certain slit and when it is inserted into a different slit. As a result, even if the spring biasing force changes due to the variation between lots or the spring biasing force is increased or decreased based on the required curtain speed, by selecting a suitable slit, the dentition portion 51 is moved to the outer periphery. Even if it is provided not in the whole area but in a part, it becomes possible to adjust the urging force within the range in which the tooth row portion 51 is provided. Note that the number of the slits 58 may be only one if the variation of the spring biasing force among lots is sufficiently small or the curtain speed is limited.

  Next, a first modification will be described. FIG. 7 is an explanatory view of the ratchet wheel 50B ′ and the locking member 140b which are the first modification. In addition, about the same structure, the overlapping description is abbreviate | omitted by attaching | subjecting the same code | symbol. The locking member 140b has claw portions 141 and 142 that are arranged in the axial direction of the ratchet wheel 50B ′ and have different lengths. The ratchet wheel 50B ′ has a tooth row portion 51 and a curved surface portion 52 formed at the upper stage, and a tooth row portion 53 ′ and a curved surface portion 54 formed at the lower stage. As with the curved surface portion 52, teeth are not formed on the curved surface portion. The pitch circle diameter and the tooth pitch are the same as those of the tooth rows 51 and 53 ', but the phases are different. For example, the dentition portions 51 and 53 'are out of phase by half the tooth pitch. Thereby, when the ratchet wheel 50B ′ is stopped because the claw portion 141 is located between adjacent teeth of the tooth row portion 51, the claw portion 142 does not contribute to the stop of the ratchet wheel 50B. When the ratchet wheel 50B ′ is stopped because the claw portion 142 is located between adjacent teeth of the tooth row portion 53, the claw portion 141 does not contribute to the stop of the ratchet wheel 50B ′. Thereby, compared with the ratchet wheel 50B shown in FIG. 5, the interval of the position where the ratchet wheel 50B ′ can be stopped is narrowed, and the position where the ratchet wheel 50B ′ can be stopped can be adjusted more finely. A slit 58 'is formed in the curved surface portion 54, and one end of the spring 59B' is engaged.

  Also in the ratchet wheel 50B ′, curved surface portions 52 and 54 on which the claw portions 141 and 142 slide are formed. For this reason, even if it is a case where two claw parts 141 and 142 are provided in order to finely adjust the position where ratchet wheel 50B 'can stop, generation of dust is controlled.

  In addition, a plurality of recesses 55 are formed on the entire circumference at regular intervals below a region where the tooth row portion 53 ′ and the claw portion 142 of the curved surface portion 54 can contact. The recess 55 is formed in a region that does not contact the claw portions 141 and 142. A disc 83 ′ is fixed to the shaft 81 ′ of the jig 80 ′, and convex portions 85 ′ are provided on the outer peripheral surface of the disc 83 ′ with a certain interval. The ratchet wheel 50B ′ is rotated by rotating the jig 80 ′ while the convex portion 85 ′ and the concave portion 55 are engaged with each other. The ratchet wheel 50B ′ can also be rotated by such a jig 80 ′. The recessed part 55 is an example of a meshing part.

  In the first modified example, the case where the lengths of the claw portions 141 and 142 are different and the phases of the tooth row portions 51 and 53 ′ are different is described, but the present invention is not limited to this. For example, the lengths of the claw portions 141 and 142 may be the same, the phases of the dentition portions 51 and 53 ′ may be different, and the lengths of the claw portions 141 and 142 may be different. The phase of 53 'may be the same.

  Next, a second modification will be described. FIG. 8 is an explanatory diagram of a ratchet wheel 50Ba according to a second modification. The radius R2 ′ of the curved surface portion 52 ′ is smaller than the root circle radius R1 of the tooth row portion 51. For this reason, after the ratchet wheel 50Ba is rotated and the claw portion 131 leaves the dentition portion 51, the tip of the claw portion 131 does not come into contact with the ratchet portion with a predetermined distance from the surface of the curved surface portion 52 ′. The car 50Ba can be rotated. Such a configuration also suppresses the generation of dust.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and modifications and changes can be made within the scope of the gist of the present invention described in the claims. Is possible.

  The focal plane shutter of the present embodiment can be employed in an optical device such as a still camera or a digital camera.

  At least one of the electromagnets 70A and 70B may be a self-holding solenoid. Further, an actuator provided with a rotor may be used as one of the drive sources of the front curtain 20A and the rear curtain 20B.

  The ratchet wheels 50B, 50B ′, and 50Ba are made of synthetic resin, but may be made of metal. This is because even in such a case, the tooth row portions 51 and 53 may be scraped to generate dust.

1 Focal plane shutter 10 Substrate 11 Opening 20A Front curtain 20B Rear curtain 21a-24a, 21b-24b Blade 31a, 31b Drive arm 32a, 32b Auxiliary arm 40A, 40B Drive lever 43a, 43b Drive pin 50B, 50B ', 50Ba Ratchet wheel 51, 53 ′ Tooth part 52, 54 Curved part 53 Tooth part (meshing part)
54B Spring (Biasing member)
55 Concave part (meshing part)
70A, 70B Electromagnet 130b, 140b Locking member 131, 141, 142 Claw

Claims (10)

A substrate having an opening;
A curtain capable of opening and closing the opening;
An electromagnet supported by the substrate;
A drive lever that has an iron piece that is attracted and held by the electromagnet and is swingably supported by the substrate;
A drive arm connected to the drive lever and swingably supported by the substrate to drive the curtain;
An urging member that urges the drive lever to run the curtain so that the iron piece is separated from the electromagnet;
A ratchet wheel that engages with the urging member to adjust the urging force of the urging member;
A locking member including a claw portion capable of stopping the ratchet wheel at a predetermined position,
The ratchet wheel has a plurality of teeth that are partially formed on the outer periphery of the ratchet wheel and that can be engaged with the claw portion, and the teeth are not formed and the claw portion can slide. A focal plane shutter comprising: a curved surface portion that is movable while facing the claw portion with a space therebetween.   The focal plane shutter according to claim 1, wherein a radius of the curved surface portion is equal to or less than a root circle radius of the dentition portion.   3. The focal plane shutter according to claim 1, wherein the ratchet wheel includes a meshing portion that can mesh with a jig for rotating the ratchet wheel and is not in contact with the claw portion. The claw portion includes first and second claw portions arranged in the axial direction of the ratchet wheel,
The dentition portion includes first and second dentition portions that can be engaged with the first and second claw portions, respectively.
The focal plane shutter according to any one of claims 1 to 3, wherein the curved surface portion includes first and second curved surface portions on which the first and second claw portions can slide.   The focal plane shutter according to claim 4, wherein the first and second claw portions have different lengths.   The focal plane shutter according to claim 4 or 5, wherein the first and second tooth row portions have different phases from each other.   The focal plane shutter according to claim 1, wherein the tooth row portion is formed in a region of 180 degrees or less on an outer periphery of the ratchet wheel.   The focal plane shutter according to claim 1, wherein the ratchet wheel has one or more slits extending in an axial direction of the ratchet wheel.   The focal plane shutter according to claim 1, wherein the ratchet wheel is made of synthetic resin. An optical apparatus comprising the focal plane shutter according to claim 1.

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