Abstract:
A shutter for a camera has a film advance mechanism for advancing film past a shutter opening and a stroboscope for emitting light. The shutter has a base plate having the shutter opening, opening sectors for undergoing opening movement in an operational state to open the shutter opening during a shutter release operation, and closing sectors for undergoing closing movement in an operational state to close the shutter opening during the shutter release operation. A first detecting device detects the operational state of the opening sectors and outputs a signal to the stroboscope to emit light. A second detecting device detects the operational state of the closing sectors and outputs a signal for winding up the film. A non-opened state of the shutter opening is detected after the shutter release operation when the second detecting device detects the operational state of the closing sectors before the first detecting device detects the operational state of the opening sectors.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a camera shutter construction and, more particularly, to a camera shutter for carrying out an exposure operation by controlling the opening and closing of shutter sectors. 
     2. Background Information 
     In a conventional camera shutter, opening and closing operations of an opening lever and a closing lever for opening and closing sectors of the shutter, respectively, are controlled, inter alia, by electromagnets for carrying out an exposure operation. The opening and closing operations of the opening and closing levers are controlled by changing the timing for turning OFF a current supplied to the electromagnets to thereby carry out the exposure operation. Furthermore, contact pieces for outputting a trigger signal of a stroboscope for emitting light are installed at a position in the vicinity of the opening lever, so that when the opening operation of the opening lever is completed, the contact pieces output the trigger signal and the stroboscope emits light. Likewise, contact pieces for outputting a signal for winding-up film are installed at a position in the vicinity of the closing lever, so that when the closing operation of the closing lever is completed, the contact pieces output the signal to wind-up the film. 
     In a conventional method of determining whether the operation for opening the shutter sectors has been carried out in the foregoing conventional camera shutter construction, a non-opening state of the shutter sectors is detected when the signal for winding-up the film has been outputted before the current supplied to the electromagnet associated with the opening lever is turned OFF after the shutter is released. 
     However, in the foregoing conventional shutter structure and operation, even when current supplied to the electromagnet associated with the opening lever is turned OFF, a determination of whether the operation for opening the shutter sectors has been carried out cannot be effectively made and, therefore, a non-opening state of the shutter sectors cannot be effectively detected. 
     The present invention overcomes many of the disadvantages inherent in conventional camera shutters by providing a camera shutter which is capable of effectively detecting a non-opening state of shutter sectors. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a camera shutter which can effectively detect a non-opening state of shutter sectors. 
     Another object of the present invention is to provide a camera shutter which can detect a non-opening state of shutter sectors by detecting a state in which closing sectors have completed a shutter closing operation before opening sectors have completed a shutter opening operation. The shutter opening and closing operations are detected by means of a trigger signal of a stroboscope for emitting light and a signal for winding up a film, respectively. 
     Another object of the present invention is to provide a camera shutter which is simple in construction and can be manufactured at low cost. 
     The foregoing and other objects of the present invention are carried out by a camera shutter comprising a base plate having a shutter opening, a plurality of opening sectors for undergoing opening movement in an operational state to open the shutter opening during a shutter release operation, and a plurality of closing sectors for undergoing closing movement in an operational state to close the shutter opening during the shutter release operation. A first detecting device detects the operational state of the opening sectors. A second detecting device detects the operational state of the closing sectors. A non-opened state of the shutter opening is detected after the shutter release operation when it is determined that the second detecting device detects the operational state of the closing sectors before the first detecting device detects the operational state of the opening sectors. 
     In another embodiment, a camera shutter according to the present invention comprises a base plate having a shutter opening, a plurality of opening sectors for undergoing opening movement in an operational state to open the shutter opening during a shutter release operation, and a plurality of closing sectors for undergoing closing movement in an operational state to close the shutter opening during the shutter release operation. A first detecting device detects the operational state of the opening sectors. A second detecting device detects the operational state of the closing sectors. A timer measures a preselected time interval from a point at which the first detecting device detects the operational state of the opening sectors. A non-opened state of the shutter opening is detected after the shutter release operation when it is determined that a time period from the point at which the first detecting device detects the operational state of the opening sectors to a point at which the second detecting device detects the operational state of the closing sectors is shorter than the preselected time interval. 
     In another embodiment, a camera shutter according to the present invention comprises a base plate having a shutter opening, a plurality of opening sectors for undergoing opening movement in an operational state to open the shutter opening during a shutter release operation, and a plurality of closing sectors for undergoing closing movement in an operational state to close the shutter opening during the shutter release operation. A first detecting device detects the operational state of the opening sector. A second detecting device detects the operational state of the closing sectors. An abnormal state of the camera shutter is detected when it is determined that the first detecting device detects the operational state of the opening sectors before the shutter release operation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing summary, as well as the following detailed description of the preferred embodiments of the invention, will be better understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the invention, there is shown in the drawings an embodiment which is presently preferred. It should be understood, however, that the invention is not limited to the precise arrangement and instrumentalities shown. In the drawings: 
     FIG. 1 is a plane view of a lens shutter showing a constitution of a first embodiment of the invention; 
     FIG. 2 is a plane view of a sector unit of the lens shutter showing the constitution of the first embodiment of the invention; 
     FIG. 3 is a plane view of the lens shutter showing a state after exposure operation of the first embodiment of the invention; 
     FIG. 4 is a plane view of the sector unit of the lens shutter showing the state after exposure operation of the first embodiment of the invention; and 
     FIG. 5 is a perspective view of essential portions of a focal plane shutter showing the constitution of a second embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     While this invention is susceptible of embodiments in many different forms, this specification and the accompanying drawings disclose only preferred embodiments of the invention. The invention is not intended to be limited to the embodiments so described, and the scope of the invention will be pointed out in the appended claims. 
     Embodiments in accordance with the present invention will be described below with reference to the accompanying drawings. 
     An explanation will be given of embodiments of the invention in reference to the drawings as follows. FIG. 1 is a plane view of a lens shutter representing a first embodiment according to the present invention. A shutter opening  3   a  is disposed at a central portion of a shutter base plate  3 . A set ring  431  is mounted on the shutter base plate  3  for pivotal movement about a circle concentric with the shutter opening  3   a . An opening lever  311  for driving opening sectors  511  and  512  (FIG. 2) is pivotably supported by a shaft  312  integral with the shutter base plate  3  proximate a peripheral portion of the set ring  431 . The opening lever  311  can be returned to an initial position when a pin  311   b  thereof is pushed by pivoting the set ring  431 . An opening lock lever  331  for holding the opening lever  311  at an opened position is pivotably supported by a shaft  332  integral with the shutter base plate  3 . An opening iron piece lever  351  for driving the opening lock lever  331  is pivotably supported by a shaft  352  integral with the shutter base plate  3 . The opening iron piece lever  351  can be attracted and held by an opening electromagnet  371 , and can be returned to an initial position when a pin  351   a  is pushed by pivoting the set ring  431 . The opening lever  311 , the opening lock lever  331  and the opening iron piece lever  351  are urged in a clockwise direction A by springs (not shown). 
     An opening switch lever  391  is also pivotably supported by the base plate  3  and is urged in the clockwise direction A by an opening switch spring  392 . The opening switch spring  392  can be brought into conductive contact with an opening switch arbor  393  by pivoting the opening switch lever  391  in the clockwise direction A to thereby turn the opening switch arbor  393  OFF. The opening switch arbor  393  is turned ON when the opening switch spring  392  is separated from the opening switch arbor  393  by pivoting the opening switch lever  391  in a counterclockwise direction B by driving the opening lever  311 . 
     The opening electromagnet  371  is positioned on the shutter base plate  3  by a boss or the like (not shown). A control device  432  detects an OFF state of the opening switch arbor  393  and controls the opening electromagnet  371 . The control device  432  comprises a CPU, a microprocessor or the like (hereinafter referred to as CPU). 
     A closing lever  321  for driving closing sectors  521  and  522  is pivotably supported by a shaft  322  integral with the shutter base plate  3  and is urged in the counterclockwise direction B by a spring (not shown). A closing lock lever  341  for holding the closing lever  321  at an opening position is pivotably supported by a shaft  342  integral with the shutter base plate  3 . A closing iron piece lever  361  for driving the closing lock lever  341  is pivotably supported by a shaft  362  integral with the shutter base plate  3 . The closing iron piece lever  361  and can be attracted and held by a closing electromagnet  381  and can be returned to an initial position by pushing a pin  361   a  of the closing iron piece lever  361  by pivoting the set ring  431 . 
     A charge lever  421  for returning the closing lever  321  to an initial position is pivotally supported by a shaft  422  integral with the shutter base plate  3  proximate a peripheral portion of the set ring  431 . The charge lever  421  is pivoted in the counterclockwise direction B by pivoting the set ring  431  and returns the closing lever  321  to an initial position by pushing a pin  321   b  of the closing lever  321 . The charge lever  421 , the closing lock lever  341  and the closing iron piece lever  361  are urged in the clockwise direction A by springs (not shown). 
     A closing switch lever  411  is disposed at a vicinity of the closing lock lever  341  and is urged in the clockwise direction A by a closing switch spring  412 . The closing switch spring  412  can be brought into conductive contact with a closing switch arbor  413  when the closing lever  321  is driven in the counterclockwise direction B to thereby turn the closing switch arbor  413  ON. The closing electromagnet  381  is positioned on the shutter base plate  3  by a boss or the like (not shown). The closing switch arbor  413  and the closing electromagnet  381  are connected to the CPU  432  which controls the closing electromagnet  381  and detects an ON state of the closing switch arbor  413 . 
     Referring now to FIG. 2, the opening sectors  511  and  512  are pivotably supported by shafts  301  and  302  below the shutter base plate and between the shutter base plate  3  and a sector holding plate  5 . The opening sectors  511  and  512  have long hole portions  511   b  and  512   b , respectively, fitted to a projection  311   a  of the opening lever  311 . Furthermore, similar to the opening sectors  511  and  512 , the closing sectors  521  and  522  are pivotably supported by shafts  303  and  304 , respectively, below the shutter base plate  3  and between the shutter base plate  3  and the sector holding plate  5 . The closing sectors  521  and  522  have long hole portions  521   b  and  522   b , respectively, fitted to a projection  321   a  of the closing lever  321 . 
     FIG. 1 shows a state in which the shutter has been charged in readiness for a shutter release operation. More specifically, the respective levers are positioned in a charged state by first pivoting the set ring  431  in the clockwise direction A, and the levers remain in a predetermined standby state by subsequently pivoting the set ring  431  in the counterclockwise direction B. At this point, the opening operation of the opening lever  311  is hampered by the opening lock lever  331 , and the opening iron piece lever  351  is attracted and held by the opening electromagnet  371 . The closing lever  321  also remains in a similar state. Also at this point, the opening switch spring  392  is brought into conductive contact with the opening switch arbor  393 , and the opening sectors  511  and  512  are in a closed state. Likewise, the closing switch spring  412  is separated from the closing switch arbor  413  by the projection  411   a  of the closing switch lever  411 , and the closing sectors are in an opened state. 
     When a shutter release operation is carried out from the state shown in FIG. 1, the set ring  431  is pivoted in the counterclockwise direction B and stops at a predetermined position (FIG.  3 ). Thereafter, the current supplied to the opening electromagnet  371  is turned OFF, and the opening iron piece lever  351  is rotated or turned in the clockwise direction A by the urging force of the springs and pivots the opening lock lever  331  in the counterclockwise direction B. As a result, the opening lever  311  is rotated in the clockwise direction A by urging force of the springs and opens the opening sectors  511  and  512 . When the shutter release operation approaches completion, the projection  311   b  of the opening lever  311  pushes the opening switch lever  391  and rotates the opening switch lever  391  in the counterclockwise direction B. Consequently, the opening switch spring  392  is separated from the opening switch arbor  393  to thereby place the opening switch arbor  393  in an OFF state. At this point, the OFF state of the opening switch arbor  393  is detected by the CPU  432  which outputs an OFF signal which is used as a trigger signal for light emission by a stroboscope (not shown). Furthermore, the OFF signal is used as a signal for detecting the termination of a driving operation of the opening sectors  511  and  512 . 
     When the CPU  432  turns OFF the current supplied to the closing electromagnet  381  after elapse of a desired exposure time period, the closing iron piece lever  361  is pivoted in the clockwise direction A, the locking state is released by pushing the closing lock lever  341  by a pin  361   b  of the closing iron piece lever  361 , and the closing lever  321  is pivoted in the counterclockwise direction B to thereby close the closing sectors  521  and  522 . When the shutter release operation approaches completion, the closing switch spring  412  is brought into conductive contact with the closing switch arbor  413  to place the closing switch arbor  413  in an ON state. At this point, the ON state of the opening switch arbor  413  is detected by the CPU  432  which outputs an ON signal which is used as a signal for winding up a film. Furthermore, the ON signal is also used as a signal for detecting the termination of a driving operation of the closing sectors. 
     By the foregoing construction and operation of the camera shutter according to the present invention, in the case in which after the shutter release operation the closing switch spring  412  is brought into conductive contact with the closing switch arbor  413  before the opening switch spring  392  is separated from the opening switch arbor  393 , the CPU  432  detects the signals from the corresponding ON/OFF state of the closing switch arbor  413  and the opening switch arbor spring  392  and outputs a signal indicating that the opening lever  311  or the closing lever  321  is not operated normally. Stated otherwise, the CPU  432  can detect that the closing sectors  521  and  522  are operated before the opening sectors  511  and  512  operate, thereby detecting a non-opened state of the opening sectors  511  and  512 . The non-opened state of the opening sectors  511  and  512  can be effectively detected even when the opening electromagnet  371  and the closing electromagnet  381  are normally controlled by the CPU  432 . 
     The camera shutter of the present invention further comprises timer means  432   a  for calculating a time period from the point when the opening switch spring  392  has been separated from the opening switch  393  and the corresponding OFF signal has been outputted to the point when the closing switch spring  412  is brought into conductive contact with the closing switch arbor  413 . By this construction, even in the case in which the opening electromagnet  371  and the closing electromagnet  381  are normally controlled by CPU  432 , when the closing switch spring  412  is brought into conductive contact with the closing switch arbor  413  in a time period shorter than a desired time period (e.g., 0.5 ms) from when the opening switch spring  392  has been separated from the opening switch arbor  393  and the OFF signal has been outputted, a signal is outputted indicating that the closing lever  321  is not operated normally. Stated otherwise, the CPU  432  can detect that the closing sectors  521  and  522  are operated before the opening sectors  511  and  512  operate, thereby detecting a non-opened state of the opening sectors  511  and  512 . 
     Moreover, an abnormality in the operation of the camera shutter of the present invention can be detected even when the opening electromagnet  371  is not turned OFF. For example, the unintentional opening of the opening sectors  511  and  512  can be detected when the CPU  432  detects the OFF signal corresponding to the opening switch spring  392  being separated from the opening switch arbor  393  before the shutter release operation. 
     FIG. 5 is a perspective view of essential portions of a focal plane shutter according to a second embodiment of the invention. 
     A shutter opening  101 C is disposed in a shutter base plate  101 . An opening lever  111  is pivotably supported by a shaft  101   a  integral with the shutter base plate  101  and is urged in the counterclockwise direction B by an opening spring (not shown). Similarly, a closing lever  121  is pivotably supported by a shaft  101   b  integral with the shutter base plate  101  and is urged in the counterclockwise direction B by a closing spring (not shown). An opening sector unit and a closing sector unit (not shown) are fitted to projections  111   b  and  121   b  of respective front ends of the opening lever  111  and the closing lever  121 . 
     A charge lever  130  is pivotably supported by a shaft  101   d  integral with the shutter base plate  101 . The opening lever  111  and the closing lever  121  are displaced to charge positions by the charge lever  130 . Movements of the opening lever  111  and the closing lever  121  are controlled by an opening electromagnet  12  and a closing electromagnet  22  which are controlled by a CPU (not shown). A printed circuit board  160  is supported by upper ends of the shafts  101   a  and  101   b , and the opening electromagnet  12  and the closing electromagnet  22  are electrically connected to the printed circuit board  160  by soldering. Opening contact pieces  161   a  and  161   b  and closing contact pieces  162   a  and  162   b  are calked to the printed circuit board  160 . 
     A boss  111   a  is connected to the opening lever  111  for pushing the contact piece  161   a  to a location proximate the termination of travel of the opening lever  111  to thereby bring the opening contact pieces  161   a  and  161   b  into electrical contact with each other. At this point, a signal representative of the contact between the opening contact pieces  161   a  and  161   b  is used both as a trigger signal for light emission by a stroboscope (not shown) and as a signal for detecting termination of a driving operation of the opening sector unit. Likewise, a boss  121   a  is connected to the closing lever  121  for pushing the contact piece  162   a  to a location proximate the termination of travel of the closing lever  121  to thereby bring the closing contact pieces  162   a  and  162   b  into contact with each other. At this point, a signal representative of the contact between the closing contact pieces  162   a  and  162   b  is used both as a trigger signal for winding up a film and as a signal for detecting termination of a driving operation of the closing sector unit. 
     During use of a camera having the focal plane shutter according to the present invention, when a photographer initiates a shutter release operation by pressing a shutter release button (not shown), the charge lever  130  is first released, and the CPU turns OFF the current supplied to the opening electromagnet  12 . As a result, the opening lever  111  is pivoted in the counterclockwise direction B by an opening spring (not shown) and opens the shutter opening  101   c . Thereafter, the boss  111   a  of the opening lever  111  approaches the opening contact piece  161   a  and is finally brought into contact therewith to thereby bring the opening contact pieces  161   a  and  161   b  into electrical contact with each other. At this point, a signal representative of the contact between the opening contact pieces  161   a  and  161   b  is used both as a trigger signal for light emission of the stroboscope and as a signal for detecting termination of the driving operation of the opening sector unit. 
     When the CPU turns OFF the current supplied to the closing electromagnet  22  after elapse of desired exposure time period, the closing lever  121  is pivoted in the counterclockwise direction B to thereby close the shutter opening  101   c . In the closing stroke of the closing lever  121 , the boss  121   a  approaches the closing contact piece  162   a  and is finally brought into contact therewith to thereby bring the closing contact pieces  162   a  and  162   b  into electrical contact with each other. At this point, a signal representative of the contact between the closing contact pieces  162   a  and  162   b  is used both as a trigger signal for winding up a film and as a signal for detecting termination of the driving operation of the closing sector unit. 
     By the foregoing construction and operation of the focal plane shutter according to the present invention, the CPU effectively detects the case in which, after the shutter release operation, the closing contact pieces  162   a  and  162   b  are brought into electrical contact with each other before the opening contact pieces  161   a  and  161   b  are brought into electrical contact with each other and outputs a signal indicating the closing lever  121  is not operated in a normal state. Thus the CPU detects that the closing sector unit is operated before the opening sector unit is operated, thereby detecting a non-opened state of the opening sector unit. 
     According to the camera shutter of the present invention, a trigger signal for light emission of a stroboscope is used as a signal for detecting termination of a driving operation of opening sectors of the camera shutter. Accordingly, even when the opening sectors are not operated properly while the opening electromagnet is turned OFF, the non-opened state of the opening sectors can be effectively detected. 
     Furthermore, an abnormality in the operation of the camera shutter of the present invention can be detected even when the opening electromagnet is not turned OFF. For example, the unintentional opening of the opening sectors can be detected when the CPU detects the OFF signal corresponding to the opening switch spring being separated from the opening switch arbor before the shutter release operation. 
     Moreover, by incorporating timer means in the camera shutter according to the present invention, the non-opened state of the opening sectors can be detected even when the closing sectors operate abnormally while the opening sectors operate without any abnormality. 
     From the foregoing description, it can be seen that the present invention comprises an improved camera shutter. It will be appreciated by those skilled in the art that obvious changes can be made to the embodiments described in the foregoing description without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but is intended to cover all obvious modifications thereof which are within the scope and the spirit of the invention as defined by the appended claims.