JP2005070454A - Focal plane shutter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep a front curtain superposed and expanded without power supply, in an initial position set state. <P>SOLUTION: In a focal plane shutter provided with an opening lever 6, a closing lever 5, and a set lever 3 for setting these levers to initial positions, the opening lever 6 is so constituted that a first opening lever 7 and a second opening lever 8 are coaxially supported one over the other. The second opening lever 8 shakably supports a driving arm 13 of a front curtain 14, and is allowed to follow the first opening lever 7, when the first opening lever 7 turns in such direction that the front curtain is superposed; and an energizing force is caused to act in the superposing direction by an energizing member 19, when the front curtain 14 is superposed; and an energizing force is caused to act in the expanding direction, when the front curtain is expanded, and thus the front curtain can be kept without power supply. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a focal plane shutter, and more particularly to a focal plane shutter used in a digital still camera.

  Many digital cameras not only allow the subject to be viewed from the viewfinder, but also display it on a liquid crystal panel so that the shutter can be pressed while checking the actual image. In order to display an image on the liquid crystal panel, it is necessary to open the shutter opening and apply light to an electronic image pickup device 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 confirming the subject on the liquid crystal panel. Therefore, after the shutter opening that has been opened 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 open. And a so-called silver film camera (hereinafter referred to as “film camera”).

Many digital cameras employ lens shutters, but recently, there are some that employ a focal plane shutter having a large shutter opening (image frame) as the number of imaging pixels increases. Many of the focal plane shutters of such digital cameras apply film plane camera focal plane shutters. Many forms of focal plane shutters for film cameras have already been proposed. As an example, by combining the attractive force of the electromagnet and the return force of the spring, the opening (shutter opening closing) and superposition (shutter opening opening) of the front curtain (opening blade) and rear curtain (closing blade) are performed. There is one (for example, Patent Document 1) that can be adapted.
JP-A-2002-214671, pages 3 to 4

  An object of the present invention is, firstly, in view of the above-mentioned circumstances, to make the above-mentioned prior art focal plane shutter for a film camera applicable as a digital camera shutter. Secondly, the front curtain can be retracted in the initial position set state before the exposure operation, and a shutter chance is not missed by quickly performing a reciprocating operation of the front curtain by a release operation. Third, it is possible to obtain a high-quality digital image by preventing the occurrence of screen unevenness in the superimposing operation of the front curtain.

  In order to achieve the above object, the focal plane shutter of the present invention employs the following configuration. The focal plane shutter basically includes an opening lever that superimposes and unfolds the front curtain, a closing lever that superimposes and unfolds the rear curtain, and a set lever that sets the opening lever and the closing lever to an initial position. It has. The first feature of the present invention is that the above-mentioned release lever swings to superimpose the front curtain, and a second release lever that can be driven by the first release lever when superimposing the front curtain. The second release lever is slidably engaged with the driving arm of the front curtain and is slidable between predetermined angular positions. Second, the second release lever is biased in the direction in which the front curtain is deployed when the front curtain is deployed, and the front curtain is superimposed when the front curtain is superimposed. A biasing member for biasing the second release lever in the direction is attached.

  The first feature is that the first release lever is set at the initial position by dividing the release lever into a first release lever for charging the front curtain and a second release lever for overlapping and unfolding the front curtain. The front curtain can be operated independently in this state. This corresponds to a unique operation of the digital camera, and contributes to constantly grasping the subject, ensuring a photo opportunity, and preventing noise. The second feature is that, by energizing the front curtain in the direction of the state in which the second release lever is expanded and overlapped with the front curtain, continuous energization for holding the shutter is unnecessary, and noise is further reduced. In addition to suppressing the occurrence, the so-called backlash of the front curtain is performed.

  According to the present invention, the front curtain can be superposed while being set at the initial position so that an image can be displayed on a liquid crystal panel or the like, and the time lag can be minimized, so that it is difficult to miss a photo opportunity. And, in order to hold the front curtain in the superimposed / deployed state, it is possible to hold the non-energized state in a state where the biasing force is biased by the biasing member regardless of the excitation of the electromagnet, thereby reducing the power consumption. In addition, since the generation of noise due to energization during exposure can be suppressed, a high quality image can be obtained.

  Next, an embodiment of the present invention will be described with reference to the drawings. 1 to 3 are enlarged views of a main part of a focal plane shutter according to the present invention. In each of these drawings, the front curtain (open blade) and the rear curtain (closed blade) are actually provided with a plurality of sheets that can be overlapped and expanded, but only one of them is provided for ease of explanation. It is shown.

  FIG. 1 shows a state in which the front curtain 14 of the focal plane shutter according to the present invention is unfolded. First, the configuration of the focal plane shutter will be described with reference to FIG. 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 having a substantially quadrangular planar shape, and the shutter is driven to the left of the image frame 1a. A mechanism 2 is provided. The shutter drive mechanism 2 includes a set lever 3 swingably provided on the left side of the center of the vertical side of the image frame 1a, a closing lever 5 and a set lever 3 swingably provided below the set lever 3. The release lever 6 provided above is provided.

  The set lever 3 is swingably supported by a first support shaft portion 1b made of a protrusion protruding from the front surface (surface of the drawing) of the shutter substrate 1. The set lever 3 is used to set the closing lever 5 and the opening lever 6 (first opening lever 7) to the initial position. The set lever 3 is swung within a predetermined angle range by a shutter charge member 4 provided in the camera body. It is possible to move. On the outer periphery of the set lever 3, there are provided the engaging recess 3a of the shutter charge member 4, the first cam portion 3b for setting the closing lever 5, and the second cam portion 3c for setting the opening lever 6. It is. The operation of the set lever 3 only reciprocates within a predetermined angle range, but the state shown in FIGS. 1 and 2 is the initial position set state in which the shutter is charged. Under this state, the closing lever 5 and the opening lever 6 are held in a charged state, so that the closing lever 5 is connected to a follower pin (not shown) projecting on the lower surface, and the first cam portion 3b is It is set at the position shown in the drawing by contact. The first release lever 7 is set at the illustrated position by a stopper portion 7b provided on the lower surface thereof coming into contact with the second cam portion 3c. When the set lever 3 is rotated about 45 ° in the clockwise direction from the above state, as shown in FIG. 3, the restriction on the closing lever 5 and the opening lever 6 is released.

  The closing lever 5 is formed of a plate-like body substantially formed in an inverted L shape, and is a second protrudingly provided on the front surface of the shutter substrate 1 inside the intersection of the long side arm portion 5a and the short side arm portion 5b. The shaft 1c is supported so as to be swingable. A first drive pin 5c is provided on the lower surface of the distal end portion of the long side arm portion 5a so as to penetrate the arc-shaped first arc groove portion 1d provided on the shutter substrate 1 and project to the back surface of the shutter substrate. The first drive pin 5c is engaged with an engagement hole (not shown) of the drive arm 11 of the rear curtain 12 provided on the back side of the shutter substrate 1 so as to be swingable. The driving arm 11 of the rear curtain 12 can be swung by swinging the closing lever 5. An auxiliary arm 11a is provided above the driving arm 11 of the rear curtain 12 so as to be parallel thereto, and a plurality of thin plate-like blades are arranged in parallel on the driving arm and the auxiliary arm. The rear curtain 12 is provided so as to be superposed and unfoldable by a link mechanism. As shown in FIG. 1, the rear curtain 12 is retracted from the image frame 1a in a state of being folded below the lower side of the image frame 1a when superimposed, and as shown in FIG. The image frame 1a is completely closed by reaching the upper side of the image frame 1a.

  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. The iron piece 5d is held by the iron core of the rear curtain electromagnet 9 provided on the upper surface of the shutter substrate 1 when the rear curtain 12 is superposed so that the superposed state can be maintained. Note that the rear curtain electromagnet 9 is not shown with a coil in the drawing. When the engagement state is released by the set lever 3 and the energization of the rear curtain electromagnet 9 is turned off, the closing lever 5 is also rotated counterclockwise by the spring force of a biasing spring (not shown). Act 12 can be deployed. 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 setting the charging state when the set lever 3 abuts when the rear curtain 12 is in the superimposed state, and sharing the releasing operation of the charging state by separation.

  As described above, the release lever 6 can swing independently in a state where the first release lever 7 and the second release lever 8 are overlapped with the third support shaft portion 1 e protruding from the shutter substrate 1. It is supported. The first release lever 7 is made of a plate-like body formed in a fan shape extending substantially 90 ° from the bearing portion supported by the third spindle 1e, and on the lower surface of one end portion of the arcuate portion, A stopper portion 7b that can be engaged with the second cam portion 3c of the set lever 3 is provided. Further, a projecting portion is formed at the end of the other arc portion of the first opening lever 7 so as to project slightly outward, and the second opening lever 8 is driven only in the counterclockwise direction at the projecting portion. A locking portion 7c is provided. Further, an iron piece 7d made of a soft magnetic material is provided at the tip of the protruding portion. The iron piece 7d can hold the unfolded state of the front curtain 14 by being attracted to the iron core of the front curtain electromagnet 10 provided on the upper surface of the shutter substrate 1 when the front curtain 14 is in the unfolded state. . The front curtain electromagnet 10 is also not shown in the coil.

  As described above, the first release lever 7 is swingably supported by the third support shaft portion 1e, but the bearing portion 7f inserted into the first release lever 7 extends so as to surround the third support shaft portion 1e. A torque adjustment dial (not shown) is provided at the upper end portion. A biasing spring 15 made of a coil spring is inserted into the bearing portion 7f. The lower end portion 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 portion of the torque adjustment dial. The urging spring 15 is attached so as to urge the first release lever 7 counterclockwise. The magnitude of the urging torque of the spring can be adjusted by a torque adjustment dial.

  The second release lever 8 is formed of a plate-like body substantially formed in an inverted shape, and is provided on the lower surface side of the first release lever 7 so as to overlap therewith. As described above, the first release lever 8 7 is supported by the third support shaft portion 1e so as to be able to swing independently. One piece of the second release lever 8 is a lever portion 8a for driving the front curtain 14, and an arc-shaped second arc groove portion 1f provided with a second drive pin 8b on the shutter substrate 1 is provided on the lower surface of the tip portion. Is provided so as to protrude through the rear surface of the shutter substrate 1. The second drive pin 8b is engaged with an engagement hole (not shown) of the drive arm 13 of the front curtain that is swingably provided on the back surface of the shutter substrate 1. An auxiliary arm 13a is provided below the driving arm 13 of the front curtain 14 so as to be parallel to the driving arm 13, and the driving arm 13 and the auxiliary arm 13a have end portions of open blades constituting the front curtain 14. The drive arm 13 and the auxiliary arm 13a of the front curtain 14 constitute a parallel link mechanism. When the second release lever 8 is rotated in the clockwise direction, the front curtain 14 is unfolded by the driving arm 13 of the front curtain 14 to close the image frame 1a. The image frame 1a is opened by superimposing the curtains.

  The other piece of the second release lever 8 is a bifurcated fork portion 8c having a groove portion in the center of the lever portion, and a slide of a drive rod 17 that advances and retreats by a motor (not shown) of the camera body in the groove portion. The pin 17a is slidably engaged. In the state shown in FIG. 1, the drive rod 17 is positioned at the uppermost position, and the second drive pin 8b of the second release lever 8 is positioned at the lowermost position of the arc groove 1f. As shown in FIG. 2, when the drive rod 17 is at the lowest position, the drive pin 8b is moved to the uppermost portion of the arc groove 1f by the single swing of the second release lever 8, and the front curtain 14 is superimposed. The image frame 1a is fully opened.

  A latch pin 8d is provided on the upper surface of the distal end portion of the lever portion 8a of the second release lever 8, and one end portion of the urging member 19 is locked thereto. The urging member 19 can urge the second release lever 8 in the direction in which the front curtain is superimposed when the front curtain is superimposed, and can be urged in the direction in which the front curtain is expanded when the front curtain is deployed. It is provided to do. As the urging member 19, a so-called turn spring is adopted in which an elastic spring material is formed so as to have a circular twisted portion at an L-shaped intersection and ring-shaped hook portions are provided at both ends. A latching portion at one end of the urging member 19 is pivotably latched by a fourth support shaft portion 1g protruding from the shutter substrate 1. The urging member 19 exerts an urging force in the expanding direction. In the state shown in FIG. 1, the urging member 19 is in an urging state in which the lever portion 8a of the second release lever 8 is pressed against the lower end of the arc groove portion 1f.

  On the other hand, in the state shown in FIGS. 2 and 3, the urging member 19 is the same in that the urging force is applied in the expanding direction, but the lever portion 8 a of the second release lever 8 is It is in the urging | biasing state pressed against the upper end of the 2nd circular arc groove part 1f. Therefore, the front curtain 14 is urged and held in the expanding direction when it is in the expanded state by the urging force of the urging member 19, and is biased and held in the overlapping direction when it is in the superimposed state. ing. For this reason, it can be held in a state of being biased to one position regardless of the attractive force of the electromagnet or the like with respect to gap distortion or the like (backlash) caused by a manufacturing error or the like. In addition, since the front curtain 14 is held in the superimposed state or the unfolded state without using electric power, it is not necessary to pass current through the electromagnet 10 during the exposure operation together with power saving, so that generation of noise can be suppressed.

  Next, the operation of the focal plane shutter according to the present invention will be described along the sequence chart shown in FIG. In the initial state of the shutter, as shown in FIG. 2, the set lever 3 is fixed at the initial position by the shutter charge member 4. As a result, both the closing lever 5 and the first opening lever 7 are set in the initial positions where they can be attracted to the electromagnets 9 and 10. In the state shown in FIG. 2, since the sector drive rod 17 is positioned at the lowest position in the front curtain 14, the second drive pin 8b is positioned at the highest position of the second arcuate groove portion 1f. Are superimposed. That is, in the initial position state of FIG. 2, since the rear curtain 12 and the front curtain 14 are overlapped, the image frame 1a is fully opened. As a result, an image can be displayed on a display unit such as a liquid crystal panel through the camera lens. At this time, the second release lever 8 is biased by the biasing member 19 in the overlapping direction.

  Next, when the release button is fully pressed at time t0, the CPU of the camera operates to energize the front curtain electromagnet 10 and the rear curtain electromagnet 9 at time t1, so that the iron pieces 5d and the first release lever of the closing lever 5 are connected to each electromagnet. 7 iron pieces 7d are adsorbed, and each lever maintains a charged state. Next, at time t2, the sector drive rod 17 is retracted (raised) by the CPU, and the second release lever 8 is rotated clockwise, the front curtain 14 is unfolded, the image frame 1a is closed, and exposure is performed. Get ready for. In this state, the front curtain 14 is urged by the urging member 19 in the direction of deployment, and is held in a so-called loose state (see FIG. 1). Next, at time t3, the shutter charge member 4 moves forward (lowers), and the set lever 3 is rotated about 45 ° clockwise to release the restrained state of the closing lever 5 and the first opening lever 7. Is done.

  Further, when a predetermined time elapses and time t4 is reached, the energization to the front curtain electromagnet 10 is turned off, and the first release lever 7 is rotated at high speed counterclockwise by the urging force of the urging spring 15. At this time, the second release lever 8 is also pushed against the urging force of the urging member 19 by the side portion of the lever portion 8a being pushed by the locking portion 7c of the first release lever 7, and rotated counterclockwise. Then, the front curtain 14 is superimposed. At the time of superimposition, as described above, the front curtain 14 is held in a superimposed state by the urging force of the urging member 19, so that so-called backlash is also performed. Further, since the urging force is acting in the superimposing direction, the bounce immediately after the leading curtain 14 is superimposed is also prevented. In addition, the resistance force by the sector drive rod 17 and the urging member 19 acts on the second release lever 8 at the time of superimposition, but since the spring force of the urging spring 15 is larger than these resistance forces, This superposition operation is not hindered.

  In this way, exposure is started when the image frame 1a is held in the fully open state. At this time, since the front curtain 14 is held by the urging member 19, it is not necessary to energize the drive motor of the sector drive rod 17. In addition, exposure is performed in the time frame (t4 to t5) in the fully open state of the image frame. However, since the front curtain 14 is held in a non-energized state, noise generation is suppressed, so that the image is read correctly. When the predetermined exposure time elapses and time t5 is reached, the energization of the rear curtain electromagnet 9 is turned off, and the closing lever 5 is rotated at high speed counterclockwise by the spring force to expand the rear curtain 12. As a result, as shown in FIG. 3, the image frame 1a is fully closed by the development of the trailing curtain 12, and the exposure ends.

  When a certain time elapses after the exposure operation is completed and time t6 is reached, the shutter charge member 4 is retracted (raised), and the closing lever 5 and the first opening lever 7 are rotated by rotating the set lever 3 counterclockwise. Set to the initial position. At this time, the first cam portion 3b of the set lever 3 pushes the follower pin of the closing lever 5 and rotates the closing lever clockwise, so that the rear curtain 12 is superimposed and the initial state shown in FIG. 2 is restored. At the same time, the first release lever 7 is set to the initial position by rotating the stopper portion 7b clockwise by the second cam portion 3c of the set lever 3. Since the second release lever 8 is held at the uppermost position of the arc groove 1f by the urging member 19, the front curtain 14 is held in a superimposed state even when the first release lever 7 is set to the initial position. The frame 1a maintains an open state. When the return operation by the set lever 3 is completed, all levers are set to the initial positions, and the image read into the image sensor at time t7 is stored in the storage element via the CPU, thereby completing one operation of photographing.

It is a front view which shows the state in which the image frame is closed by expansion | deployment of the front curtain in the example of 1 form of this invention. FIG. 6 is a front view showing a state in which the image frame is closed by the development of the rear curtain. Similarly, it is a front view showing a state where the image frame is fully open. It is a sequence diagram of a focal plane shutter in one example of the present invention.

Explanation of symbols

1 Shutter board 1a Picture frame (shutter opening)
3 Set lever 4 Shutter charge member 5 Closing lever 5d, 7d Iron piece 6 Opening lever 7 First opening lever 7c Locking portion 8 Second opening lever 9, 10 Electromagnet 11, 13 Driving arm 12 Rear curtain (closing blade)
15 Biasing spring 14 Front curtain (open blade)
17 Sector drive rod

Claims (1)

An opening lever that superimposes and unfolds the front curtain, a closing lever that superimposes and unfolds the rear curtain, and a set lever that sets the opening lever and the closing lever to an initial position,
The release lever coaxially supports a first release lever that swings to overlap the front curtain, and a second release lever that can be driven by the first release lever when the front curtain overlaps. ,
The second release lever engages with the driving arm of the front curtain so as to be swingable, and is swingable between predetermined angular positions.
The second release lever biases the second release lever in the direction in which the front curtain expands when the front curtain is expanded, and in the direction in which the front curtain overlaps when the front curtain is superimposed. A focal plane shutter, wherein a biasing member for biasing the second release lever is attached.