JP4549125B2 - Focal plane shutter for digital still camera - Google Patents

Description

  The present invention relates to a focal plane shutter for a digital still camera having one shutter blade.

Among the focal plane shutters for digital still cameras, there is one shutter blade composed of a plurality of arms pivoted at one end with respect to the main plate and at least one blade pivotally supported by these arms. There are things that only have. In the shutter blade, one of the arms is connected to the drive pin of the drive member, and the drive member is reciprocally rotated to open and close the opening for the photographing optical path. In addition, it is also known that the drive member is rotated to one side by a set member interlocked with a motor and rotated to the other side by a biasing force of a spring. Attention has been paid to those that can be reciprocated only by a motor. As a further advancement, Patent Document 1 discloses a drive member integrated with a rotor of a motor.
JP 2002-287210 A

  Incidentally, the drive device described in Patent Document 1 has a configuration suitable for downsizing, and is extremely effective for space saving in the camera. However, in terms of production, it may not always be convenient. Normally, the drive member is a member that operates at a considerably high speed and receives a large impact by contacting the stopper when stopped. Therefore, the rotor must have a large starting force and can withstand such an impact. However, since the drive device described in Patent Document 1 is for assembling the motor components one by one on the shutter base plate, whether or not such performance can be obtained is checked after the shutter is assembled. It can only be done. If the result of the inspection indicates that it is inconvenient, the motor components must be disassembled and reassembled, making the operation extremely cumbersome and costly. There is a problem.

  The present invention has been made to solve such problems, and an object of the present invention is to open and close the shutter blade of a digital still camera focal plane shutter having only one shutter blade. Even if a versatile and inexpensive DC motor (direct current motor) is used as a drive source to perform the assembly process, the transmission structure for the shutter blade drive member is simple, so the size is reduced. It is to provide a focal plane shutter for a digital still camera that is extremely effective for cost reduction.

In order to achieve the above object, a focal plane shutter for a digital still camera according to the present invention includes two ground planes each having an opening for exposure and forming a blade chamber therebetween, One shutter that is arranged in a blade chamber and includes a plurality of arms each having one end rotatably attached to one of the base plates, and at least one blade pivotally supported by the arms. The shutter includes a blade, a DC motor capable of reciprocating rotation attached to one of the base plates, and a driving pin connected to one of the arms, and is reciprocally rotated by the DC motor. in the vicinity of the fully open and the drive member for causing opening and closing operation of the opening in the blade, the opening a before the shutter blade is stopped in the fully open the opening And location and the shutter blade is equipped with a detecting means for detecting at least one of the positions in the vicinity of the fully closed the opening A before the stop by the opening to the fully closed, the detection the detection signal of the means to restrict or cut to so that the driving current of the DC motor.

  In that case, the DC motor may be attached to one of the ground planes with its output shaft parallel to the optical axis, and the drive member may be attached to the output shaft. In addition, if a bearing member is attached to any one of the ground plates, and the tip of the output shaft to which the drive member is attached is supported by the bearing member, it is extremely practical. It becomes a suitable structure.

Further, the DC motor, the output shaft in parallel to the optical axis attached to the base plate, the output shaft is mounted spur gear, wherein the drive member is meshed with the spur gear Rights A gear may be integrally attached. Furthermore, at least one gear may be interposed between the spur gear attached to the output shaft and the spur gear of the drive member. In these cases, it is advantageous in terms of cost if the drive member and the gear attached to the drive member are manufactured as a single member of synthetic resin.

In the present invention, the DC motor may be a DC motor with a speed reduction mechanism. Further, in the present invention, before Symbol detection means, the first and the light sensor for detecting the shutter blade in the vicinity of a position of fully opening the opening, the opening in the vicinity of the position where the fully closed A second optical sensor that detects shutter blades may be configured to limit or cut the driving current of the DC motor by each detection signal. Further, the detection means is an optical sensor that detects a shutter blade in a state where the opening is approximately half open, and a delay circuit is activated by the detection signal, and after a predetermined time, the driving current of the DC motor is limited or It can be cut.

  The present invention uses a versatile and inexpensive DC motor that has been completed as a motor unit in advance as a drive source for opening and closing the shutter blade in a digital plane camera focal plane shutter having one shutter blade. In addition, since the transmission configuration of the shutter blades to the drive member is simple, the shutter assembly process becomes efficient, and it is extremely effective for miniaturization and cost reduction.

Embodiments of the present invention will be described with reference to four illustrated examples. In each of these embodiments, a general-purpose DC motor that does not incorporate a speed reduction mechanism is used as a driving source for the shutter blades. In the case of a focal plane shutter for a digital still camera, even if the configuration is exactly the same, one of two operation methods (normally open method and normally close method) is adopted depending on the design specifications of the camera. However, these embodiments will be described on the assumption that the normally open method is adopted. 1 to 7 are for explaining the first embodiment, and FIGS. 8 and 9 are for explaining the second embodiment. 10 to 15 are for explaining the third embodiment, and FIG. 16 is for explaining the fourth embodiment. Of these, FIGS. 1 and 2 apply to the second embodiment, and FIG. 7 also applies to the third embodiment. 9 to 11 are also applied to the fourth embodiment.

  The present embodiment will be described with reference to FIGS. FIG. 1 is a plan view for explaining the configuration of the driving apparatus according to the first embodiment, and FIG. 2 is a longitudinal sectional view of FIG. 3 to 7 are for explaining the operation of this embodiment, and FIG. 3 is a plan view showing an initial state in which the shutter blades fully open the exposure opening. 4 is a plan view showing a state immediately after the shutter blade starts closing the exposure opening, and FIG. 5 is a plan view showing a state immediately before the shutter blade finishes closing the exposure opening. FIG. 7 is a plan view showing a state in which the shutter blade is stopped immediately after the exposure opening is closed, and FIG. 7 is a timing chart for explaining a series of operations.

  First, the configuration of the drive device of this embodiment will be described. The shutter base plate 1 is formed with an opening 1a for exposure in which a rectangle is horizontally long and an arc-shaped long hole 1b. FIG. 1 shows a part of the left side of the shutter base plate 1. Therefore, only a part of the opening 1a is shown. As shown in FIGS. 2 and 3, an auxiliary ground plate 2 having substantially the same outer shape as the shutter ground plate 1 is attached to the back side of the shutter ground plate 1 with a predetermined interval by means not shown. The blade chamber is formed between the shutter base plate 1 and the shutter blade disposed in the blade chamber is not shown in FIGS. 1 and 2. The auxiliary base plate 2 is also formed with an opening 2a having a slightly larger shape than the opening 1a. The shape of the opening 2a is shown in FIG. Therefore, in this embodiment, the opening 1a of the shutter base plate 1 regulates the exposure opening. Further, a long hole 2b (see FIG. 2) having the same shape is formed in the auxiliary base plate 2 at a position overlapping the long hole 1b of the shutter base plate 1.

  As can be seen from FIG. 2, a bearing member 3 is attached to the shutter base plate 1 with a plain washer 4 sandwiched between the shutter base plate 1 and caulking on the blade chamber side. The bearing member 3 has a flange portion 3a at the tip protruding outside the blade chamber. A bearing hole 3b perpendicular to the shutter base plate 1 is formed at the center of the front end surface. Further, a first shaft portion 3c is provided between the flange portion 3a and the shutter base plate 1, and a second shaft portion 3d is provided in the blade chamber. A plate member 5, a brake member 6, a plate member 7, and a spring washer 8 are sequentially attached to the first shaft portion 3c from the shutter base plate 1 side.

Among them, the spring washer 8 is for pressing the brake member 6 toward the plate member 5 and applying a frictional force to the rotation of the brake member 6, and the bent portion 8 a is formed in the hole 1 c of the shutter base plate 1. (The illustration is omitted in FIG. 1) so that it does not rotate with the brake member 6. The two plate members 5 and 7 are made of synthetic resin and serve to increase the frictional force when the brake member 6 rotates. Further, as can be seen from FIG. 1, the brake member 6 has a V-shaped planar shape, and the bent portions 6 a and 6 b formed at the tips of the two arm portions are formed on the shutter base plate 1. Is inserted into the long hole 1b.

  An attachment plate 11 is attached to the surface outside the blade chamber of the shutter base plate 1 by two screws 9 and 10. The mounting plate 11 has an upright portion 11a bent vertically with respect to the shutter base plate 1 and a mounting portion 11b bent further in parallel with the mounting portion 11b. The motor 12 is attached by two screws 13 and 14 with its output shaft 12a parallel to the optical axis O (that is, perpendicular to the shutter base plate 1). The DC motor 12 includes, for example, a permanent magnet in the stator and a coil in the rotor (armature), and the rotor continuously rotates by changing the direction of the current flowing in the coil. This is an inner rotor type motor. And in order to keep the attachment state of this DC motor 12 reliably, the front-end | tip of the output shaft 12a is fitted in the bearing hole 3b of said bearing member 3 so that rotation is possible. Further, the synthetic resin driving member 15 integrally attached to the output shaft 12a by press-fitting processing inserts the driving pin 15a into the blade chamber from the long hole 1b formed in the shutter base plate 1. ing.

  Next, the configuration of the shutter blades arranged in the blade chamber will be described with reference to FIG. The shutter blade of this embodiment is composed of two arms 16 and 17 and four blades 18, 19, 20 and 21. First, the arm 16 is rotatably attached to the second shaft portion 3d (see FIG. 2) with one end in the longitudinal direction as a pivot portion, and the driving pin is inserted into a known long hole (not shown). 15a is fitted. The arm 17 is rotatably attached to a shaft 1 d provided on the blade base side of the shutter base plate 1. As is well known, the four blades 18, 19, 20, and 21 are connected to both of the arms 16 and 17 through two connecting shafts from the pivoting portion side to the other end. In turn.

  Finally, a shutter blade position detection device will be described. Two optical sensors 22 and 23 are attached to the surface of the shutter base plate 1 outside the blade chamber. These photosensors 22 and 23 are well-known photoreflectors, each having a light emitting portion and a light receiving portion, which are exposed to a blade chamber from a hole (not shown) formed in the shutter base plate 1. Yes. Further, the surface of the auxiliary base plate 2 on the blade chamber side is a reflecting surface in the area facing the optical sensors 22 and 23, and the light emitted from the light emitting part is reflected by the reflecting surface and then enters the light receiving part. It is supposed to be.

  Next, the operation of the present embodiment will be described. As is well known, the operation of the shutter for the digital still camera is performed in one of two sequences. One of them is the initial state where the shutter blades close the exposure opening. When the release button is pressed during shooting, the shutter blades start immediately from the initial state. It is called. The other is the initial state where the shutter blades are fully open, and even if the release button is pressed during shooting, the shutter blades do not operate immediately, and in the final stage of shooting. It is called a normally open type that starts from its initial state. Although the shutter of this embodiment can be operated in any sequence, the case of operating in a normally open type sequence will be described below with reference to FIGS.

  FIG. 3 shows an initial state (shooting standby state) in which the shutter blade fully opens the opening (exposure opening) 1a. At this time, the drive member 15 is in a clockwise rotation limit position, and the drive pin 15a makes the bent portion 6a of the brake member 6 contact the lower end of the long hole 1b. At this time, the light sensor 23 mainly has the blade 21, so that the light emitted from the light emitting unit does not enter the light receiving unit, and the detection signal is at the L level as shown in FIG. In the sensor 22, the light emitted from the light emitting unit enters the light receiving unit, and the detection signal is at the H level. In this initial state, the photographer can observe the subject image with the liquid crystal display device.

  When the release button is pressed at the time of shooting, the charge accumulated in the solid-state imaging device is released, and the accumulation of charges for shooting is started. When a predetermined time elapses, a drive current is supplied to the DC motor 12 by a signal from the exposure time control circuit. Thereby, the rotor of the DC motor 12 rotates in the forward direction (counterclockwise in FIG. 3) and rotates the driving member 15 attached to the output shaft 12a in the counterclockwise direction. 21 starts moving upward while reducing the overlap between adjacent blades. At this time, the brake member 6 continues to maintain the state of FIG. 3 due to the frictional force applied by the spring washer 8 even after the drive member 15 starts to operate. Further, the detection signal of the optical sensor 23 is maintained at the L level until the four blades 18 to 21 are in the state shown in FIG. 4, but when the blades 18 are further raised from the state of FIG. The light emitted from the light emitting part and reflected by the auxiliary ground plane 2 reaches the light receiving part and switches to the H level.

  After that, when the four blades 18 to 21 are further raised to the state shown in FIG. 5, the detection signal of the optical sensor 22 is blocked by the blade 21 until the light that has been incident on the light receiving unit so far. Switch to L signal. Therefore, the drive current supplied to the DC motor 12 is cut, and thereafter, the rotor, the drive member 15, and the shutter blades of the DC motor 12 operate only with inertia. Immediately thereafter, the drive pin 15a comes into contact with the bent portion 6b of the brake member 6 that has remained in the state shown in FIGS. 3 to 5 so as to rotate the brake member 6 counterclockwise. Therefore, after that, the rotation of the driving member 15 is braked, and immediately after the four blades 18 to 21 completely close the opening 1a, the bent portion 6b is at the upper end of the long hole 1b. Stops by contacting. FIG. 6 shows the stop state. In such a closed state, the imaging information is transferred from the solid-state imaging device to the storage device.

  By the way, in this embodiment, the drive current of the DC motor 12 is cut immediately before the shutter blades completely close the opening 1a. Therefore, thereafter, since the drive pin 15a pushes the brake member 6 only by inertia, the operation of the drive member 15 and the shutter blade is suitably braked, and the bent portion 6b of the brake member 6 is the upper end of the long hole 1b. When the contact is made, the bounce generated thereby is suppressed, and the phenomenon that the shutter blade temporarily opens the upper region of the opening 1a does not occur. Therefore, it is possible to transfer the imaging information as described above at an early stage and obtain an image without uneven exposure, and thus it is possible to start the set operation described below at an early stage. The next shooting can be done quickly.

  When the imaging information is transferred to the storage device in this way, a drive current in the reverse direction is supplied to the DC motor 12 by the end signal, and the output shaft 12a is rotated clockwise in FIG. . As a result, the drive pin 15a of the drive member 15 rotates the arm 16 in the clockwise direction, so that the four blades 18 to 21 start moving downward while increasing the overlap between adjacent blades. At this time, the brake member 6 continues to maintain the state of FIG. 6 by the frictional force applied by the spring washer 8 even after the operation of the drive member 15 is started. In addition, the detection signal of the optical sensor 22 generates an L level signal by the blades 20 and 21 until the four blades 18 to 21 continue to move downward and reach the state shown in FIG. However, when the blades 21 are further lowered from the state of FIG. 5, the light emitted from the light emitting part and reflected by the auxiliary base plate 2 reaches the light receiving part and is switched to an H level signal. Therefore, from that stage, the detection signals of the two optical sensors 22 and 23 are both at the H level.

  Thereafter, when the four blades 18 to 21 are further lowered to the state shown in FIG. 4, the detection signal of the optical sensor 23 blocks the light that has been incident on the light receiving unit until then by the blade 18, and thus the L level. Switch to Therefore, the drive current supplied to the DC motor 12 is cut, and thereafter, the rotor, the drive member 15 and the shutter blades of the DC motor 12 operate only with inertia. Immediately after that, the drive pin 15a comes into contact with the bent portion 6a of the brake member 6 and rotates the brake member 6 in the clockwise direction, so that their operation is braked, and the bent portion 6a is inserted into the long hole 1b. Stopping by contacting the lower end completes the setting operation. The stop state is the initial state shown in FIG. At this time, since the opening 1a is fully open, the subject image can be observed again by the liquid crystal display device.

  By the way, in the case of the present embodiment, the drive current of the DC motor 12 is cut immediately before the shutter blades fully open the opening 1a even when returning to the initial state in this way. Therefore, after that, the operation of the drive member 15 and the shutter blade is suitably braked, and when the bent portion 6a of the brake member 6 comes into contact with the lower end of the long hole 1b, the bounce generated thereby is suppressed, and the shutter The phenomenon that the blades temporarily cover the lower region of the opening 1a does not occur. Therefore, in the case of the present embodiment, immediately after the four blades 18 to 21 of the shutter blades fully open the opening 1a, it is possible to immediately start the exposure for the next photographing. There is no risk of missing the photo opportunity. In addition, in this way, the next shooting can be performed quickly, and exposure unevenness caused by the above phenomenon is eliminated, which is advantageous in the case of continuous shooting.

  In the above description, the case where the driving current of the DC motor 12 is cut when one of the detection signals is switched to the L level from the state where the detection signals of the two sensors 22 and 23 are at the H level has been described. However, as indicated by broken lines A and B in FIG. 7, the drive current may be gradually limited. In that case, the continuously supplied current may be gradually decreased from that time point, or the current that has been supplied in a pulse manner is narrowed from that point. Then, the duty ratio may be lowered. Further, the current that has been continuously supplied until then may be pulse-energized from that point to decrease the duty ratio. In the present embodiment, the two sensors 22 and 23 are provided, but only one of them may be used. In such a case, when the detection signal is changed from the H level to the L level, the drive current is limited or cut. When only the sensor 22 is provided, the imaging information to the storage device is provided. Only the sensor 23 is provided, and if only the sensor 23 is provided, it is possible to start the next shooting at an early stage and eliminate uneven exposure. These are the same as in the case of Example 3 described below.

  Next, Example 2 will be described. FIG. 8 shows a state in which the shutter blade of the present embodiment closes the exposure opening substantially half after starting the closing operation from the initial state shown in FIG. 3 like the shutter blade of the first embodiment. FIG. 9 is a timing chart for explaining the operation of the present embodiment. The shutter of this embodiment is provided with a single optical sensor 24 as shown in FIG. 8, whereas the shutter of the first embodiment is provided with two optical sensors 22 and 23. is there. Other mechanical structures of the present embodiment are the same as those of the first embodiment. Therefore, in FIG. 8, the same reference numerals as those in the first embodiment are used for those members and parts.

  The photosensor 24 of the present embodiment is a photo reflector having the same configuration as the two photosensors 22 and 23 of the first embodiment, but its mounting position is the vertical direction of the opening 1a as can be seen from FIG. In other words, in other words, a position where the four blades 18 to 21 of the shutter blade cover the opening 1a by about half. However, an electronic circuit (not shown) is provided with a delay circuit, and the drive current of the DC motor 12 is limited or cut after a predetermined delay time after the detection signal of the optical sensor 24 is switched. Yes.

  Then, next, the operation of the present embodiment will be described. In the description, in addition to using FIGS. 8 and 9, FIGS. 3 to 6 used in the description of the operation of the first embodiment are applied mutatis mutandis. 3 to 6 in that case are assumed to be provided with the optical sensor 24 shown in FIG. 8 instead of the optical sensors 22 and 23. Further, the points in common with the operation description of the first embodiment will be described as simply as possible.

  Also in this embodiment, the initial state is the state shown in FIG. 3 above, and at this time, the detection signal of the optical sensor 24 in this embodiment is at the H level. The subject image can be observed by the liquid crystal display device. When the release button is pressed at the time of shooting, the charge accumulated in the solid-state imaging device is released, and the accumulation of charges for shooting is started. When a predetermined time elapses, a drive current is supplied to the DC motor 12 by a signal from the exposure time control circuit. As a result, the rotor of the DC motor 12 rotates in the forward direction, and the driving member 15 integrated with the output shaft 12a is rotated in the counterclockwise direction, so that the four blades 18 to 21 start moving upward.

  When the four blades 18 to 21 are in the state shown in FIG. 8 through the state of FIG. 4, the signal emitted from the optical sensor 24 is switched from the H level to the L level, and the operation of the delay circuit is started. . Thereafter, when the four blades 18 to 21 are further moved up to the state shown in FIG. 5, the predetermined delay time X1 (see FIG. 9) ends, and the drive current supplied to the DC motor 12 is cut. Therefore, the rotor of the DC motor 12, the driving member 15, and the shutter blade are thereafter operated only by inertia, and the driving pin 15 a of the driving member 15 is braked by pushing the bent portion 6 b of the brake member 6. And as shown in FIG. 6, it stops when the bending part 6b of the brake member 6 contact | abuts to the upper end of the long hole 1b. Thus, also in the case of the present embodiment, since the bounce at the time of stop is suitably suppressed, it is possible to transfer the imaging information from the solid-state imaging device to the storage device immediately after the opening 1a is closed. At the same time, it is possible to obtain an image without uneven exposure.

  Thereafter, when the imaging information is transferred to the storage device, a drive current in the reverse direction is supplied to the DC motor 12 by the end signal, and the output shaft 12a is rotated clockwise in FIG. Therefore, the arm 16 is rotated clockwise through the drive pin 15a, and the four blades 18 to 21 are moved downward. Then, when those four blades 18 to 21 change to the state of FIG. 8 through the state of FIG. 5, immediately after that, the signal emitted from the optical sensor 24 switches from the L level to the H level. Start.

  Thereafter, when the four blades 18 to 21 are in the state shown in FIG. 4, the predetermined delay time X <b> 2 (see FIG. 9) ends, and the drive current supplied to the DC motor 12 is cut. Therefore, the rotor of the DC motor 12, the drive member 15, and the shutter blades thereafter operate only by inertia, but the operation is suitably braked by the drive pin 15a pushing the bent portion 6a of the brake member 6. When the bent portion 6a comes into contact with the lower end of the long hole 1b, it stops without bouncing. In the stopped state (the state shown in FIG. 3), the subject image can be observed by the liquid crystal display device.

  Thus, in the case of this embodiment, only one optical sensor is provided, but by providing a delay circuit, it is equivalent to the case where two optical sensors are provided as in the first embodiment. It is possible to get functions. In the above description of the operation, the case where the driving current of the DC motor 12 is cut when the delay times X1 and X2 are finished is explained. However, in the case of the present embodiment, as in the case of the first embodiment, As indicated by broken lines A and B in FIG. 9, the drive current may be gradually limited. In this case, the supply current may be continuously reduced, or the duty may be increased. You may make it lower in order. This is the same in the case of Example 4 below.

  Next, a present Example is described using FIGS. FIG. 10 is a plan view for explaining the configuration of the drive device according to the third embodiment, and FIG. 11 is a longitudinal sectional view of FIG. 12 to 15 are for explaining the operation of this embodiment. FIG. 12 is a plan view showing an initial state in which the shutter blades fully open the exposure opening. 13 is a plan view showing a state immediately after the shutter blade starts closing the exposure opening, and FIG. 14 is a plan view showing a state immediately before the shutter blade finishes closing the exposure opening. These are top views which show the state which the shutter blade | wing stopped immediately after closing exposure opening. 7 used for explaining the operation of the first embodiment is also used for explaining the operation of the present embodiment.

  First, the configuration of this embodiment will be described. By the way, in the case of the present embodiment, the configuration of the shutter blades arranged in the blade chamber is exactly the same as in the case of the first and second embodiments. The configuration of the shutter blade position detection device is exactly the same as in the first embodiment. Therefore, those constituent members and parts are denoted by the same reference numerals as those in the first embodiment, and the description of the configuration thereof is omitted. Therefore, the configuration of the present embodiment will be described only for the driving device, but the same members as those in the first embodiment are often used for the driving device. Therefore, such substantially the same members and their parts are denoted by the same reference numerals as those in the first embodiment, and description thereof will be made simply.

  The shutter base plate 1 of this embodiment forms an opening 1a for exposure in which a rectangle is horizontally long and an arc-shaped long hole 1b. As shown in FIG. 11, an auxiliary base plate 2 is attached to the back side of the shutter base plate 1 at a predetermined interval by means not shown, and a blade chamber is formed between the shutter base plate 1 and the shutter base plate 1. is doing. Also, the auxiliary base plate 2 is formed with an opening 2a (see FIG. 12) slightly larger than the opening 1a so as to overlap with the opening 1a, and substantially the same shape so as to overlap with the elongated hole 1b. A long hole 2b (see FIG. 11) is formed.

  As can be seen from FIG. 11, the shaft 31 is erected on the shutter base plate 1 by sandwiching the flat washer 4 between the shaft 31 and the shutter base plate 1 and by caulking on the blade chamber side. The shaft 31 has a first shaft portion 31b and a second shaft portion 31c formed with the flange portion 31a as a boundary outside the blade chamber, and a third shaft portion 31d inside the blade chamber. Yes. In addition, a screw hole is formed in the axial direction from the distal end surface of the first shaft portion 31b. Then, as in the case of the first embodiment, a plate member 5, a brake member 6, a plate member 7, and a spring washer 8 are sequentially attached to the second shaft portion 31c from the shutter base plate 1 side. 6, the two bent portions 6a and 6b are inserted into the long holes 1b of the shutter base plate 1 as shown in FIG. 10, and the bent portions 8a of the spring washer 8 are provided on the shutter base plate 1 to prevent rotation. It is inserted into the hole 1c (see FIG. 11).

  A synthetic resin drive member 32 is rotatably attached to the first shaft portion 31b of the shaft 31. The drive member 32 has a gear portion 32a and a drive pin 32b. The drive pin 32b is inserted into the blade chamber from the long hole 1b formed in the shutter base plate 1, and the shutter blade is inserted into the blade chamber. It is made to fit in the long hole which is formed in one arm 16 of this. In the case of the present embodiment, the gear portion 32a is formed at the same time as the injection molding of the drive member 32. However, the gear portion 32a is separately manufactured as a metal annular part, and the drive member 32 is injected. It may be integrated at the time of molding.

  Two shafts 1e and 1f are erected on the surface of the shutter base plate 1 outside the blade chamber, and screw holes are formed on the front end surfaces thereof. A mounting plate 33 is attached to the two shafts 1e, 1f and the tip of the shaft 31 by three screws 34, 35, 36. The mounting plate 33 is a motor of the same type as the DC motor 12 of the first embodiment, but a DC motor 37 having a higher rotational speed than the DC motor 12 has its output shaft 37a parallel to the optical axis O. That is, it is attached by two screws 38 and 39 perpendicular to the shutter base plate 1. A spur gear 40 is integrally attached to the output shaft 37a. Further, the shutter base plate 1 is provided with a shaft 1 g, and the tip of the shaft 1 g is fitted in the hole of the mounting plate 33. A spur gear 41 is rotatably attached to the shaft 1g, and the rotation of the spur gear 40 is decelerated and transmitted to the drive member 32.

Next, the operation of this embodiment will be described with reference to FIG. 7 in addition to FIGS. 12 to 1 5. However, since the operation sequence is very similar to that of the first embodiment, common points will be briefly described. In the case of this embodiment as well, since it is operated in a normally open mode, as shown in FIG. 12, the initial state of the shutter blades (shooting standby state) is a state where the opening 1a is fully opened. At this time, the drive member 32 is in a clockwise rotation limit position, and the drive pin 32b makes the bent portion 6a of the brake member 6 contact the lower end of the long hole 1b. At this time, as shown in FIG. 7, the detection signal of the optical sensor 22 is at the H level, and the detection signal of the optical sensor 23 is at the L level.

  When the release button is pressed at the time of shooting, the charge accumulated in the solid-state imaging device is released, and the accumulation of charges for shooting is started. When a predetermined time elapses, a drive current is supplied to the DC motor 37 by a signal from the exposure time control circuit. Thereby, the rotor of the DC motor 37 rotates in the forward direction (counterclockwise in FIG. 12), and the spur gear 41 for reduction is rotated in the clockwise direction via the spur gear 40 attached to the output shaft 37a. Let Therefore, the drive member 32 in which the gear portion 32a meshes with the spur gear 41 is rotated counterclockwise, and the arm 16 is rotated counterclockwise by the drive pin 32b. As a result, the four blades 18 to 21 start moving upward. And if the blade | wing 18 raises further from the state of FIG. 13, the output signal of the sensor 23 will switch from L level to H level.

  Thereafter, when the four blades 18 to 21 are further raised to the state shown in FIG. 14, the detection signal of the optical sensor 22 is switched to the L signal. Therefore, the drive current supplied to the DC motor 37 is cut, and thereafter, the rotor, the spur gear 40, the spur gear 41, the drive member 32, and the shutter blade of the DC motor 37 operate only by inertia. . Immediately thereafter, the drive pin 32b contacts the bent portion 6b of the brake member 6 and rotates the brake member 6 counterclockwise. Therefore, after that, the rotation of the driving member 32 is braked, and immediately after the four blades 18 to 21 completely close the opening 1a, the bent portion 6b is at the upper end of the long hole 1b. Stops by contacting. FIG. 15 shows the stop state. In the case of the present embodiment, the drive member 32 does not bounce when the bent portion 6b comes into contact with the upper end of the long hole 1b. Then, since the imaging information is immediately transferred from the solid-state imaging device to the storage device, an image without uneven exposure can be obtained.

  When the imaging information is transferred to the storage device in this way, a reverse drive current is supplied to the DC motor 37 by the end signal, and the spur gear attached to the output shaft 37a in FIG. 40 is rotated clockwise. Accordingly, the drive member 32 is rotated clockwise through the spur gear 41, and the arm 16 is rotated clockwise by the drive pin 32b, so that the four blades 18 to 21 move downward. Get started. Then, when the blade 21 is further lowered from the state of FIG. 14, the output signal of the optical sensor 22 is switched from the L level to the H level. Therefore, from that stage, the detection signals of the two optical sensors 22 and 23 are both at the H level.

  Thereafter, when the four blades 18 to 21 are further lowered to the state of FIG. 13, the detection signal of the optical sensor 23 is switched to the L level. Therefore, the drive current supplied to the DC motor 37 is cut, and thereafter, the rotor, the spur gear 40, the spur gear 41, the drive member 32, and the shutter blades of the DC motor 12 are operated only by inertia. Become. Immediately thereafter, the drive pin 32b comes into contact with the bent portion 6a of the brake member 6 and rotates the brake member 6 in the clockwise direction, so that their operation is braked and the bent portion 6a is inserted into the elongated hole 1b. Stops by contacting the lower end. FIG. 12 shows the initial state of stopping in this manner, but in the case of the present embodiment, the drive member 32 does not bounce when the bent portion 6a contacts the lower end of the long hole 1b. Therefore, when this fully opened state is reached, exposure for the next photographing can be started immediately. This eliminates the possibility of missing the photo opportunity for the next shooting, and is advantageous when performing continuous shooting.

  In this embodiment, the spur gear 41 for speed reduction is provided, but the diameter of the spur gear 40 attached to the output shaft 37a is increased and directly meshed with the gear portion 32a of the drive member 32. By doing so, the spur gear 41 becomes unnecessary. However, if the spur gear 41 for reduction is provided as in this embodiment, the degree of freedom increases in the position where the DC motor 37 is arranged, which is advantageous in terms of camera design. This is also true when the low speed DC motor 12 of the first and second embodiments is used instead of the DC motor 37 of the present embodiment, and a gear having the same diameter as the spur gear 40 is used instead of the spur gear 41. The same. Further, when the DC motor 37 of the present embodiment is a DC motor with a speed reduction mechanism, the spur gear 41 can be dispensed with without increasing the diameter of the spur gear 40. Furthermore, when a DC motor with a speed reduction mechanism is used, it is possible to directly attach the drive member 32 not formed with the gear portion 32a to the output shaft as in the first and second embodiments. . The present invention includes all those aspects, and this is the same as in the case of Example 4 below.

  Next, Example 4 will be described. The shutter of this embodiment is provided with a single sensor 24 as shown in FIG. 16, whereas the shutter of the third embodiment is provided with two optical sensors 22 and 23. . Other mechanical structures of the present embodiment are exactly the same as those of the third embodiment. Therefore, in FIG. 16, the same reference numerals as those in the third embodiment are used for those members and parts. FIG. 16 shows a state in which the shutter blade of the present embodiment closes the exposure opening substantially half after starting the closing operation from the initial state shown in FIG. 12, similarly to the shutter blade of the third embodiment. FIG.

  The photosensor 24 of the present embodiment is a photo reflector having the same configuration as the two photosensors 22 and 23 of the third embodiment. The mounting position of the photosensor 24 is the same as that of FIG. The four blades 18 to 21 are positioned so as to detect a state where the half of the opening 1a is covered. Further, the shutter of this embodiment is provided with a delay circuit as in the second embodiment, and after a predetermined delay time after the detection signal of the optical sensor 24 is switched, the drive current of the DC motor 37 is supplied. Limit or cut. Therefore, the operation of the present embodiment will be described next. In describing the operation, in addition to using FIG. 16, FIGS. 12 to 15 used in the description of the operation of the third embodiment and the operation description of the second embodiment. The used FIG. 9 is applied mutatis mutandis. Therefore, in FIGS. 12 to 15 in that case, the optical sensor 24 shown in FIG. 16 is attached instead of the optical sensors 22 and 23.

  The initial state of this embodiment is the state shown in FIG. 12, and at this time, the detection signal of the optical sensor 24 is at the H level. When the release button is pressed in this state, the charge accumulated in the solid-state image sensor is released and the accumulation of charge for photographing is started. When a predetermined time elapses, a drive current is supplied to the DC motor 37 by a signal from the exposure time control circuit. As a result, the rotor of the DC motor 37 rotates in the forward direction, and the spur gear 40 integral with the output shaft 37a is rotated in the counterclockwise direction, so that the arm 16 is counterclockwise via the spur gear 41 and the drive member 32. And the four blades 18 to 21 are moved upward.

  When the four blades 18 to 21 are in the state shown in FIG. 16 through the state of FIG. 13, the signal emitted from the optical sensor 24 is switched from the H level to the L level, and the operation of the delay circuit is started. The Thereafter, when the four blades 18 to 21 are further moved up to the state shown in FIG. 14, the predetermined delay time X (see FIG. 9) ends, and the drive current supplied to the DC motor 37 is cut. Therefore, the rotor of the DC motor 37, the spur gear 40, the spur gear 41, the drive member 32, and the shutter blade are thereafter operated only by inertia, and the drive pin 32a of the drive member 32 is the bent portion 6b of the brake member 6. It is braked by pressing. And as shown in FIG. 15, it stops when the bending part 6b of the brake member 6 contact | abuts to the upper end of the long hole 1b. Thus, in the case of the present embodiment as well, since the bounce at the time of stopping is suitably suppressed, immediately after the opening 1a is closed, the imaging information without uneven exposure is transferred from the solid-state imaging device to the storage device. Is possible.

  When the imaging information is transferred to the storage device in this way, a drive current in the reverse direction is supplied to the DC motor 37 by the end signal, and in FIG. 15, the spur gear 40 integrated with the output shaft 37 is provided. It can be rotated clockwise. Therefore, the arm 16 is rotated clockwise through the spur gear 41 and the drive member 32, and the four blades 18 to 21 are moved downward. Then, when those four blades 18 to 21 are in the state of FIG. 16 through the state of FIG. 14, the signal emitted from the optical sensor 24 is switched from the L level to the H level immediately after that, so that the delay circuit operates. Start.

  Thereafter, when the four blades 18 to 21 are in the state shown in FIG. 13, the predetermined delay time X (see FIG. 9) ends, and the drive current supplied to the DC motor 37 is cut. Therefore, the rotor of the DC motor 37, the spur gear 40, the spur gear 41, the drive member 32, and the shutter blade are thereafter operated only by inertia, but the drive pin 32b is a bent portion of the brake member 6. When the bent portion 6a comes into contact with the lower end of the long hole 1b, the driving member 32 does not bounce and stops in the state shown in FIG. Therefore, also in the present embodiment, when the opening 1a is fully opened, the next photographing can be started immediately. This eliminates the possibility of missing a photo opportunity, which is advantageous when performing continuous shooting.

  In each of the above embodiments, the DC motors 12 and 37 are attached to the shutter base plate 1 with their output shafts 12a and 37a being parallel to the optical axis O. However, the present invention is not limited to this mode, and it may be mounted so as to be orthogonal to the optical axis O (that is, parallel to the shutter base plate 1) by interposing a worm and a worm wheel. Absent. In each of the above embodiments, one or two optical sensors are used as the shutter blade position detecting means. However, the detecting means of the present invention is not limited to the optical sensor, but a magnetic sensor. Other non-contact type sensors may be used. In addition to the types of photosensors that receive reflected light, such as the photoreflector described in the embodiment, there are types of optical sensors that receive light emitted from the light emitting unit directly at the light receiving unit. The optical sensor of the present invention can be either.

FIG. 4 is a plan view for explaining the configuration of the drive device according to the first embodiment. It is a longitudinal cross-sectional view of FIG. It is a top view of Example 1 which showed the initial state in which the shutter blade has fully opened the exposure opening. FIG. 4 is a plan view showing a state in which the shutter blade starts the closing operation from the initial state of FIG. 3 and starts closing the exposure opening. FIG. 5 is a plan view showing a state in which the shutter blade has reached from the state of FIG. 4 just before the exposure opening is closed. FIG. 6 is a plan view showing a state in which the shutter blade closes the exposure opening from the state of FIG. 5 and stops immediately thereafter. 3 is a timing chart for explaining the operation of the first embodiment. FIG. 9 is a plan view of Example 2 in which the shutter blade starts closing operation from the initial state and closes the exposure opening substantially half. 6 is a timing chart for explaining the operation of the second embodiment. FIG. 10 is a plan view for explaining a configuration of a drive device according to a third embodiment. It is a longitudinal cross-sectional view of FIG. It is a top view of Example 3 which showed the initial state which the shutter blade | wing fully opens exposure opening. FIG. 13 is a plan view showing a state in which the shutter blade starts the closing operation from the initial state of FIG. 12 and starts closing the exposure opening. FIG. 14 is a plan view showing a state in which the shutter blade has reached from the state of FIG. 13 just before closing the exposure opening. FIG. 15 is a plan view showing a state in which the shutter blade closes the exposure opening from the state of FIG. 14 and stops immediately after that. FIG. 10 is a plan view of Example 4 in which the shutter blade starts closing operation from the initial state and closes the exposure opening substantially half.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shutter base plate 1a, 2a Opening part 1b, 2b Long hole 1c Hole 1d, 1e, 1f, 1g, 31 Shaft 2 Auxiliary base plate 3 Bearing member 3a, 31a Flange part 3b Bearing hole 3c, 31b 1st shaft part 3d, 31c 1st Two shaft parts 4 Plain washers 5, 7 Plate members 6 Brake members 6a, 6b, 8a Bent parts 8 Spring washers 9, 10, 13, 14, 34-36, 38, 39 Screws 11, 33 Mounting plates 11a Standing parts 11b Mounting portion 12, 37 DC motor 12a, 37a Output shaft 15, 32 Drive member 15a, 32b Drive pin 16, 17 Arm 18, 19, 20, 21 Blade 22, 23, 24 Optical sensor 31d Third shaft portion 32b Gear portion 40 , 41 Spur gear O Optical axis

Claims (9)

Two ground planes each having an opening for exposure and constituting a blade chamber between them, and one end of each of the ground planes arranged in the blade chamber so that one end can be rotated. A shutter blade comprising a plurality of attached arms and at least one blade pivotally supported by the arms; and a DC motor capable of reciprocating rotation attached to any one of the base plates; A drive member having a drive pin coupled to one of the arms and reciprocally rotated by the DC motor to cause the shutter blade to open and close the opening, and the shutter blade to the opening The position before the stop with the opening fully opened and in the vicinity of the opening with the opening fully opened and the shutter blade before the stop with the opening fully closed and the opening fully closed A detecting means for detecting at least one of the position that is near, comprise a digital still camera which is characterized in that so as to restrict or cut the driving current of the DC motor in detection signal of said detecting means Focal plane shutter.   2. The DC motor according to claim 1, wherein the DC motor is attached to one of the ground plates with an output shaft parallel to the optical axis, and the drive member is attached to the output shaft. Focal plane shutter for digital still cameras.   3. The digital still according to claim 2, wherein a bearing member is attached to any one of the base plates, and a tip end of the output shaft to which the driving member is attached is supported by the bearing member. Focal plane shutter for camera. Said DC motor, the output shaft in parallel to the optical axis attached to the base plate, the output shaft is mounted spur gear, also the drive member is meshed with the spur gear Rights The focal plane shutter for a digital still camera according to claim 1, wherein gears are integrally attached.   5. The focal plane shutter for a digital still camera according to claim 4, wherein at least one gear is interposed between a spur gear attached to the output shaft and a spur gear of the drive member.   6. The focal plane shutter for a digital still camera according to claim 4, wherein the driving member and a gear attached to the driving member are made of synthetic resin as one member.   The focal plane shutter for a digital still camera according to any one of claims 1 to 6, wherein the DC motor is a DC motor with a speed reduction mechanism. A first optical sensor for detecting the shutter blade in the vicinity of a position at which the opening is fully open; and a second optical sensor for detecting the shutter blade in the vicinity of a position at which the opening is fully closed. the optical sensor, in each of the detection signals, the digital still camera focal plane shutter according to any one of claims 1 to 7, characterized in that so as to restrict or cut the driving current of the DC motor. The detection means, an optical sensor that detects the shutter blade in a state in which the opening is open about half exerts a delay circuit in the detection signal of that, after a predetermined time, limiting the driving current of the DC motor or cut 8. The focal plane shutter for a digital still camera according to claim 1 , wherein the focal plane shutter is for digital still camera.