JP4086702B2 - Focal plane shutter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a focal plane shutter, and more particularly to a focal plane shutter used in a digital still camera (hereinafter referred to as “digital camera”).
[0002]
[Prior art]
Many digital cameras allow a subject to be viewed through a viewfinder and displayed on a liquid crystal panel so that a shutter can be pressed while checking an actual image. In order to display an image on the liquid crystal panel in this way, it is necessary to open the shutter opening and apply light to an electronic image sensor such as a C-MOS or CCD to convert the image into a digital signal. For this reason, the shutter opening is opened even during non-shooting, and the release button is pressed for shooting after the subject is confirmed by looking at the liquid crystal panel. Therefore, after the opened shutter opening is once closed, the shutter is opened and closed again, and the image on the image sensor is converted into a signal while the shutter opening is fully opened. It is different from a film type camera (hereinafter referred to as “film type camera”).
[0003]
Many digital cameras employ lens shutters, but recently, there are some that adopt a focal plane shutter having a large image frame (shutter opening) as the number of imaging pixels increases. These focal plane shutters are applications of the focal plane shutters of film cameras, but many forms of focal plane shutters for film cameras have already been proposed. As a first example, by combining the attractive force of the electromagnet and the return force of the spring, the front curtain (opening blade) and the rear curtain (closing blade) are deployed (opening the frame opening) and superimposed (opening the frame opening). ) There is an apparatus (for example, Patent Document 1) that performs an operation. As a second example, a moving motor composed of a permanent magnet rotor and a stator coil is used to open and close by swinging a sector arm that opens and closes a shutter blade by a predetermined angle. (For example, Patent Document 2).
[0004]
[Patent Document 1]
JP-A-2002-214671, pages 3 to 4 [Patent Document 2]
JP-A-2001-215556, pages 3 to 5
[Problems to be solved by the invention]
When the focal plane shutter of the first example is employed in a digital camera, it is difficult to retract the front curtain before releasing and to illuminate the image sensor to display the subject on the liquid crystal panel. This is because digital cameras require that the front curtain be retracted before the release operation, whereas film cameras require that the shutter be completely closed before the release operation. This is because of the difference.
[0006]
In the second example, since the front curtain is reciprocated only by the moving motor, it is difficult to increase the shutter speed as compared with the conventional spring-driven focal plane shutter.
[0007]
The object of the present invention is, firstly, in view of the above-mentioned situation, the focal plane shutter for the film camera of the first example can be applied as much as possible and applied as a shutter for a digital camera, and a subject can be displayed on a liquid crystal panel. There is to do. Second, it is possible to reduce power consumption and suppress noise by enabling the front curtain to be superposed and unfolded while being kept in a non-energized state. A third object of the present invention is to provide a digital camera that prevents the occurrence of a time lag by making it possible to quickly reciprocate the front curtain by a release operation, so as not to miss a photo opportunity.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a focal plane shutter according to the present invention includes a front curtain and a rear curtain that open and close an image frame of a shutter substrate by overlapping and unfolding operations, an opening lever that operates the front curtain, The following means is adopted for a focal plane shutter having a closing lever for operating the rear curtain and a set lever for setting the opening lever and the closing lever to the initial position. That is, according to the present invention, the first release lever and the second release lever are overlapped with each other to provide coaxial support, and the second release lever supports the driving arm of the front curtain in a swingable manner. The first release lever can be driven when it rotates in the direction in which the front curtain overlaps, and the second release lever can be swung by an actuator that can be held in a non-energized state at a predetermined position. There is.
[0009]
Further, the present invention is characterized in that, in the above means, when the release lever is set by the set lever, the front curtain can be superimposed or unfolded by the actuator. Whereas the previous curtain of the focal plane shutter has been opened and closed by a combination of an electromagnet and a spring, the focal plane shutter of the present invention performs the opening and closing operation of the front curtain as described above. In addition to being able to be performed by combination, when the release lever is set by the set lever, that is, even when charged, the front curtain is driven by an actuator that is a drive means different from the above drive source. It can be superimposed or expanded. This makes it possible to cope with functions unique to the digital camera by superimposing or unfolding the front curtain even when the set lever is set.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings. 1 to 3 are enlarged views of the main part of the focal plane shutter according to the present invention, and FIGS. 4 and 5 are further enlarged views of the main part of FIG. In each of these drawings, the front curtain (open blade) and the rear curtain (closed blade) are actually composed of a plurality of blades that can be overlapped and deployed, but here, for ease of explanation. Each of them shows only one slit forming blade as a representative.
[0011]
FIG. 1 shows one state of the above focal plane shutter. As shown in FIG. 1, an image frame (shutter opening) 1a is provided at a position on the right side of the central portion of the shutter substrate 1 formed in a substantially rectangular shape, and a shutter drive mechanism 2 is provided on the left side of the image frame. It is. The shutter drive mechanism 2 is provided above the set lever 3, which is swingably provided on the left side of the central portion in the drawing, and above the set lever 3, which is provided swingably below the set lever. An opening lever 6 is provided. The release lever 6 is a composite lever composed of a first release lever 7 and a second release lever 8 supported coaxially.
[0012]
The set lever 3 is swingably supported by a first support shaft 1b made of a protrusion protruding from the front surface (surface of the drawing) of the shutter substrate 1, and is set in a predetermined angle range by a shutter charge member (not shown). It can be turned. The set lever 3 is for charging a spring (not shown) that drives the closing lever 5 and the opening lever 6, and a first cam for setting the closing lever 5 to an initial position is provided on the outer periphery of the set lever 3. A second cam portion 3c for setting the portion 3b and the release lever 6 to the initial position is provided (see FIG. 4). In the set lever 3, the state shown in FIGS. 1 and 3 (FIG. 4) is a state in which the closing lever 5 and the opening lever 6 (first opening lever 7 described later) are charged to the initial position, and FIG. A state in which the charge state is released by rotating clockwise by about 45 ° with respect to the charge state is shown. When the set lever 3 is rotated counterclockwise by the shutter charge member from the state shown in FIG. 2, the closing lever 5 and the opening lever 6 are again set to the initial positions shown in FIG.
[0013]
As shown in FIGS. 1 to 3, the closing lever 5 is formed of a plate-like body substantially formed in an L shape, and the shutter substrate 1 is formed at the intersection of the long side arm portion 5 a and the short side arm portion 5 b. The second support shaft 1c protruding from the front surface is supported so as to be swingable. A first drive pin 5c that passes through an arc-shaped first groove 1d provided in the shutter substrate 1 and protrudes toward the back side of the shutter substrate is provided on the lower surface of the distal end portion of the long side portion 5a. The first drive pin 5c is engaged with an engagement hole (not shown) of a rear curtain drive arm 11 provided on the back side of the shutter substrate 1 so as to be swingable. The rear curtain drive arm 11 swings around the pin protruding from the back surface side of the second support shaft 1c by swinging the closing lever 5. An auxiliary arm 11a is provided above the rear curtain drive arm 11 so as to be parallel to the rear curtain drive arm 11. A plurality of thin blades can be superimposed and deployed on the drive arm 11 and the auxiliary arm 11a. (Blade) 12 is provided. The rear curtain 12 is retracted from the image frame 1a while being folded below the lower side of the image frame 1a, as shown in FIG. 1, when superimposed by the parallel link mechanism by the drive arm 11 and the auxiliary arm 11a. At the time of unfolding, as shown in FIG. 2, the unfolding is performed up to the upper side of the image frame 1a to completely close the image frame 1a.
[0014]
An iron piece 5d made of a soft magnetic material is provided at the tip of the short side arm portion 5b of the closing lever 5. This iron piece 5d can hold the superposed state by being attracted to the iron core of the first electromagnet 9 provided on the upper surface of the shutter substrate 1 when the rear curtain 12 is superposed. Although the first electromagnet 9 is not shown in the drawing in the drawing, when the energization of the coil is turned off when the engagement state of the closing lever 5 is released by the set lever 3, the closing lever 5 Is rotated counterclockwise by the spring force of an urging spring (not shown) to deploy the rear curtain 12. A follower pin (not shown) that can come into contact with the first cam portion 3 b of the set lever 3 is provided on the lower surface of the short side arm portion 5 b of the closing lever 5. The follower pin plays a role of sharing the charge of the closing lever 5 and the releasing operation thereof by contact with the first cam portion 3 b of the set lever 3.
[0015]
As shown in FIG. 4, the release lever 6 is, as described above, the first release lever 7 provided swingably by being supported by the third support shaft 1e protruding from the shutter substrate 1. The second release lever 8 is provided so as to be independently swingable in a state of being overlapped with the first release lever 7. The first release lever 7 is formed of a plate-like body that is formed in a fan shape that extends substantially 90 ° from the bearing portion supported by the third support shaft 1e, and the second cam portion of the set lever 3 is formed on the lower surface of one end portion. A stopper portion 7b that can be engaged with 3c is provided. Further, an extension portion is formed at the other end of the first release lever 7 so as to protrude slightly outward, and a second release lever 8 is provided on the rear side (lower part of the drawing) of the extension portion. A locking portion 7c that is driven only when it is rotated counterclockwise is suspended downward (see FIG. 5). Further, an iron piece 7d made of a soft magnetic material is provided at the tip of the extending portion. The iron piece 7d is capable of holding the first release lever 7 in a charged state by being attracted to the iron core of the second electromagnet 10 provided on the upper surface of the shutter substrate 1. Although the coil of the second electromagnet 10 is also omitted, the first release lever 7 is biased by a biasing spring 15 (see FIG. 5) that is fitted to the third spindle 1e when the coil is turned off. 5)) and is urged to rotate counterclockwise.
[0016]
The urging spring 15 utilizes the torque generated by the torsional force of the coil spring. As shown in FIG. 5, the third support shaft 1e supporting the release lever 6 is moved upward (to the right in the drawing). It is attached by being inserted into a stretched column part. The lower end portion (left end portion in FIG. 5) of the biasing spring 15 is fixed to the upper surface of the first release lever 7, and the upper end portion is fixed to the lower surface of the adjustment dial 19. The adjustment dial 19 is used to adjust the strength of the urging spring when assembling the camera equipped with the shutter.
[0017]
As shown in FIG. 4, the second release lever 8 is formed of a plate-like body formed in a pistol shape, and is swingably supported by a third support shaft 1 e that is coaxial with the first release lever 7 described above. A second drive pin 8b is formed on the lower surface of the distal end portion of the lever portion 8a of the second release lever 8 so as to pass through an arc-shaped second groove portion 1f provided in the shutter substrate 1 and protrude to the rear surface of the shutter substrate 1. Is provided. Since the second drive pin 8b is slidable along the second groove 1f, the second release lever 8 can swing within the range of the second groove 1f. The second drive pin 8b passes through the second groove portion 1f and protrudes from the back surface of the substrate 1. The second drive pin 8b fits into the engagement hole portion 13b of the open blade arm 13 swingably provided on the back surface of the shutter substrate 1. ing. The open blade arm 13 swings around the pin protruding from the back side of the third spindle 1e as the center of rotation by swinging the second release lever 8.
[0018]
An auxiliary arm 13a is provided below the open blade arm 13 so as to be parallel to the open blade arm 13, and a plurality of thin blades can be superimposed and deployed on the open blade arm 13 and the auxiliary arm 13a. A curtain (open blade) 14 is provided. The front curtain 14 constitutes a parallel link mechanism by the open blade arm and the auxiliary arm 13a. With this parallel link mechanism, the opening blade arm 13 swings when the second release lever 8 rotates in the clockwise direction, the front curtain 14 is unfolded to close the image frame 1a and rotate counterclockwise. When moving, the front curtain is overlapped to open the image frame. The other outer peripheral portion of the second release lever 8 is provided with a fork portion 8c having a groove portion between the two forks. A sliding pin 17e (see FIG. 5) of an actuator 17 provided on the left side of the release lever 6 is slidably engaged with the fork portion 8c along the groove portion of the fork portion.
[0019]
As shown in FIGS. 4 and 5, the actuator 17 includes a stator 17b, a coil 17c, and a rotor 17d. The actuator 17 has the same structure as the known moving motor described in the section of the prior art. This actuator 17 is provided with two non-energized holding positions on the stator 17b surrounding the rotor 17d, and when combined with a two-pole permanent magnet rotor, a magnetic pole is generated in the stator 17a when a current signal is input. It is designed to rotate. When the stator 17b is in one of the two non-energized holding positions, the front curtain 14 is in a superimposed state, and when it is in the other position, the front curtain 14 is in a deployed state. The drive lever 17a is provided on the rotor 17d.
[0020]
Output of the driving force by the actuator 17 to the second release lever 8 is performed via a drive lever 17a provided on a rotor shaft 17f integrated with the rotor 17d. That is, since the driving pin 17e provided at the tip of the driving lever 17a is engaged with the groove portion of the fork portion 8c of the second opening lever 8, the second opening lever 8 is rotated by the rotation of the rotor 17d. It can swing (see FIG. 5). As will be described later, the actuator 17 allows the front curtain 14 to be unfolded by rotating the second release lever 8 in preparation for the next exposure operation while keeping the first release lever 7 in a charged state.
[0021]
Next, the operation of the focal plane shutter according to the present invention will be described along the sequence chart shown in FIG. The shutter charge member shown in this figure is not shown in the above figures, but indicates a member for setting the set lever 3 and is not shown provided in the camera body. The set lever 3 is provided so as to be rotatable within a predetermined angle range by a motor. The shutter curtain slit indicates the positional relationship between the rear curtain 12 and the front curtain 14. The rear curtain 12 is located outside the lower side (Y :-) of the image frame 1a and the front curtain. When 12 is positioned outside the upper side (Y: +) of the image frame 1a, the shutter is fully open, and conversely, either the rear curtain 12 or the front curtain 14 reaches the outside of the opposite side of the image frame 1a. This indicates that the shutter is fully closed.
[0022]
The horizontal axis of this diagram indicates time (t). When the camera is not used and when the camera is switched on, the closing lever 5 and the first opening lever 7 are initially set by the set lever 3. The position is set to the position (see FIG. 3). At this time, the rotor 17d is positioned at one of the non-energized holding positions of the stator 17b, and the second release lever 8 is not positioned when the second drive pin 8b is positioned at the upper end of the second groove 1f by the actuator 17. Energized and held. Further, at this time, both the rear curtain 12 and the front curtain 14 are overlapped, so that the image frame 1a is fully opened. Accordingly, light enters the image pickup device from the image frame 1a through the lens of the camera. If the switch of the liquid crystal panel of the camera is turned on at this time, an image is displayed on this.
[0023]
Next, when the release button is fully pressed (t0), the CPU of the camera operates to energize the rear curtain electromagnet 9 and the front curtain electromagnet 10 at time t1, so that each electromagnet has the iron piece 5d and the first release lever of the closing lever 5. 7 iron pieces 7d are adsorbed. Next, at time t2 when a predetermined time elapses, a current of one pulse is supplied to the actuator 17 by the CPU, and the rotor 17d of the actuator rotates counterclockwise. Along with this, the second release lever 8 rotates clockwise through the fork portion 8c to expand the front curtain 14. Therefore, at time t3, the image frame 1a is fully closed (see FIG. 1). At this time, the actuator 17 is fixed at the static stable position when the magnetic pole of the rotor 17d coincides with the other non-energized holding position of the stator 17b. For this reason, the second release lever 8 is held in a non-energized state with the front curtain 14 in a deployed state.
[0024]
Here, the shutter charge member causes the set lever 3 to rotate about 45 ° in the clockwise direction, and the set state of the closing lever 5 and the opening lever 6 is released (see FIG. 2). Even when the set state is released, the closing lever 5 and the first opening lever 7 are attracted and fixed by the rear curtain electromagnet 9 and the front curtain electromagnet 10, so that the rear curtain 12 and the front curtain 14 are held at their current positions. Next, at time t4, the energization of the front curtain electromagnet 10 is turned off, and the fixed state of the first release lever 7 is released. Therefore, the first release lever is activated by the spring force of the biasing spring 15 (see FIG. 5). Rotates counterclockwise. At this time, the second release lever 8 is also driven by the locking portion 7c of the first release lever 7 and rotated counterclockwise. For this reason, the second release lever 8 rotates against the magnetic holding force of the actuator 17 described above, and the front frame 14 is superposed to open the image frame 1a for exposure. Next, when the exposure time elapses and time t5 is reached, the energization of the rear curtain electromagnet 9 is turned off by the CPU. For this reason, the iron piece 5d of the closing lever 5 is separated from the rear curtain electromagnet 9, the rear curtain 12 is developed by the biasing force of a return spring (not shown), and the image frame 1a is closed (see FIG. 2), so that exposure is performed. finish.
[0025]
At time t6 after the exposure is completed, the set lever 3 is rotated counterclockwise via the shutter charge member by the signal transmission from the CPU, and the closing lever 5 and the first opening lever 7 are returned to the initial positions. . That is, the set lever 3 rotates the closing lever 5 clockwise by the first cam portion 3b, and is set at a position where the iron piece 5d can be attracted to the rear curtain electromagnet 9. The first release lever 7 is also rotated clockwise by the second cam portion 3c of the set lever, and similarly, the iron piece 7d is set at a position where it can be attracted to the front curtain electromagnet 10. Thus, at time t7, the trailing curtain 12 is completely superimposed, and one shutter operation by photographing is completed. At this time, since the protrusion 8b is left at the upper end of the second groove 1f of the second release lever 8 due to the non-energization holding force of the actuator, the front curtain 14 maintains the overlapping state and fully opens the image frame 1a. An image can be displayed on the liquid crystal panel. Further, the actuator 17 can be used to increase the shutter speed, reduce the impact when the front curtain 14 is superimposed, or prevent balun. For example, the energization of the front curtain electromagnet 10 is turned off, the first release lever 7 is rotated by the spring force of the urging spring 15, and the front curtain 14 is moved to the actuator 17 at the timing when the front curtain 14 starts to move. When a driving pulse is applied to operate in the direction, that is, the direction in which the front curtain 14 is superimposed, the driving force of the actuator 17 is added to the spring force of the biasing spring 15 to increase the operating speed of the front curtain 14 to increase the speed. Immediately before the travel of the curtain 14 is finished, the actuator 17 is given a drive pulse that operates in the direction opposite to the travel direction of the front curtain 14 to generate a braking force, so that the impact at the end of the travel of the front curtain 14 can be reduced. Immediately after the end of travel, the actuator 17 can be given a drive pulse that operates in the same direction as the travel direction of the front curtain 14 to prevent the balun at the end of travel of the front curtain 14.
[0026]
【The invention's effect】
According to the present invention, the front curtain can be held in the superimposed or deployed position with power saving by adopting a configuration in which the second release lever can be swung by an actuator that can be held in a non-energized state at a predetermined position.
Further, the front curtain can be brought into a superimposed state or a deployed state when being set by the set lever.
[Brief description of the drawings]
FIG. 1 is a front view showing a state in which an image frame is closed by developing a front curtain.
FIG. 2 is a front view showing a state in which an image frame is closed by developing the rear curtain.
FIG. 3 is a front view showing a state in which the image frame is fully opened.
4 is an enlarged view of a release lever driving mechanism shown in FIG. 3; FIG.
FIG. 5 is an enlarged cross-sectional view of FIG.
FIG. 6 is a sequence diagram of a focal plane shutter according to the present invention.
[Explanation of symbols]
1 Shutter board 1a Picture frame (shutter opening)
3 Set lever 5 Closing lever 5d, 7d Iron piece 6 Opening lever 7 First opening lever 8 Second opening lever 9, 10 Electromagnet 12 Rear curtain (closing blade)
13 Driving arm 14 Front curtain (open blade)
17 Actuator

Claims (1)

By being rotated by the shutter charge member, the front and rear curtains that open and close the image frame of the shutter substrate by superimposing and unfolding operations, the opening lever that operates the front curtain, the closing lever that operates the rear curtain, and , and a set lever for setting the said opening lever and the closing lever in the initial position,
The release lever is coaxially arranged between a first release lever that is biased by a biasing spring in a direction in which the front curtain is superimposed, and a second release lever that can be driven by the first release lever when the front curtain is superimposed. As support,
The second release lever supports the driving arm of the front curtain so as to be swingable , and is swingable by an actuator capable of holding the second release lever at a predetermined position without energization ,
When the first opening lever and the closing lever are set to the initial positions by the set lever, the actuator can swing the second opening lever by energization, and the second opening lever by non-energization. It can be kept in a non-energized position,
Even when the front curtain is in the unfolded state, when the first release lever is swung by the urging force of the urging spring, the first release lever follows the second release lever and moves the front curtain. A focal plane shutter that is superimposed .

Images