JPS6161662B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an electromagnetic drive shutter for opening and closing a camera shutter by electromagnetic drive.

In the past, mechanical power was often used as the drive source for driving the shutter of a camera. In other words, the shutter drive spring is charged at the same time as the film is wound, etc., and the force of this spring is used to drive the shutter in conjunction with the shutter release.In such mechanical shutters, the force of the charged spring is used for the release operation. It had a locking member at the front, and a mechanism to release it with a release operation. Therefore, with this type of camera, there is no risk of the shutter opening accidentally and exposing the camera during normal use, and there is no risk of such an accident unless the shutter button is pressed with some force. It was hot.

In an electromagnetic drive shutter, an electromagnetic device converts electrical energy into mechanical energy and uses this force to drive the shutter member, and generally there is no need for a spring driving force, and the electromagnetic device is energized by operating the shutter release. It was thought that a locking member like a mechanical shutter was not necessary because the driving force was generated by the shutter blades and the shutter blades were actuated by this. However, when an electromagnetic shutter camera is carried or stored, if gravity, vibration, shock, etc. act on the shutter blade, depending on the configuration of the shutter blade, the shutter will open naturally and the film will be exposed. Accidents may occur, and some measures must be taken to prevent this. Furthermore, when shooting for a long time with an electromagnetically driven shutter camera, it is desirable to cut off the power to the electromagnetic device for a period of time after the exposure run in one direction is completed and until it is restored in order to save power. In this case, the shutter blades were held only by frictional force, and the above-mentioned accidents were likely to occur.

The present invention has been made in view of the above points, and when the movable element in the electromagnetic drive source that electromagnetically drives the shutter blades moves incorrectly from the travel end position, the electromagnetic drive source is moved in the travel end direction. This is an electromagnetic drive shutter configured to return the vehicle to its original travel end position.

With the above configuration, in the present invention, when the shutter blade moves from the travel end position due to the action of a shock or the like, it is immediately returned to the original travel end position by the electromagnetic driving force.
It is possible to provide an electromagnetic drive shutter that can prevent accidents such as erroneous film exposure.

Embodiments of the present invention will be described in detail below with reference to the drawings.

A first embodiment is shown in FIG. 1 and subsequent figures.

FIG. 1a is a perspective view showing an embodiment of an electromagnetic drive device according to the present invention, in which one shutter blade of a slit exposure shutter or the like is driven. In the figure, 1
a, 1b and 1c are yokes, 2a to 2d are flat permanent magnets such as rare earth magnets, and the permanent magnet 2
A to 2d are magnetized as shown in the figure, and are held sandwich-like by the yoke as shown. 5a and 5b are magnetic gaps between the yokes 1a and 1b and 1b and 1c, respectively, and the permanent magnet 2
Due to the magnetomotive forces a to 2d, magnetic flux is generated in the vertically downward direction in the magnetic gap 5a, and in the vertically upward direction in the magnetic gap 5b. These electromagnetic members are fixed to the camera base.

Reference numeral 3 denotes a □-shaped coil winding frame bobbin inserted around the yoke 1b, and a coil 4 is wound on the bobbin 3. When the coil 4 starts to be energized, the bobbin receives a force due to the interaction between the energized current and the magnetic flux generated in the gaps 5a and 5b, and starts to move in the left-right direction. A shutter blade (not shown) is fixed to the bobbin 3. 3a is a protrusion of the bobbin 3, and a triangular prism-shaped high magnetic permeability member 4a is fixed to the protrusion. 1a-1
is a protrusion of the yoke 1a, and a coil b is attached to the protrusion.
is wrapped. 1b-1 is a protrusion of the yoke 1b, and the protrusion 1b-1 forms a magnetic gap 7 with the protrusion 1a-1. A magnetic flux is generated in the magnetic gap 7 by the magnetomotive force of the permanent magnets 2a and 2c, and when the bobbin 3 moves rightward, the high magnetic permeability member 4a generates a magnetic flux in the gap 7. Attracted by magnetic flux, Figure 1b
As shown in , the protrusions 1a-1 and 1b of the yoke
Adsorbs to -1. If the position of the bobbin 3 at this time is made to correspond to the shutter closed state, the shutter closed state is determined by the magnetic flux of the high magnetic permeability member 4a and the protrusions 1a-1 and 1b-1 of the yoke. It is held by adsorption force.

By the way, when the member 4a shown in FIG. 1b is in contact with the protrusions 1a-1 and 1b-1 of the yoke, the magnetic resistance of the magnetic gap 7 is extremely reduced, so the magnetic flux generated from the permanent magnets 2a and 2c is Most of the magnetic flux flows through the protrusions 1a-1 and 1b-1 of the yoke, and the magnetic flux generated in the magnetic gap 5a rapidly decreases. However, when the shutter is in the closed state, there is no need to apply force in the left and right directions to drive the shutter blades on the bobbin 3.
Therefore, the sudden decrease in the magnetic flux of the magnetic gap 5a does not pose a practical problem. At the time of shutter release, for example, in the case of a single-lens reflex camera, upon completion of the upward movement of the quick return mirror, the coil 6 is energized to generate a magnetomotive force in the opposite direction to the permanent magnets 2a and 2c. and 2c, the protrusions 1a-1 and 1b of the yoke
Make the magnetic flux flowing to -1 zero. In this state, the high magnetic permeability member 4a and the protrusions 1a-1 and 1 of the yoke
The adsorption force with b-1 disappears. Furthermore, by energizing the coil 6, the magnetic flux from the permanent magnets 2a and 2c flows through the gap 5a, and the magnetic flux from the permanent magnets 2a and 2c flows through the gap 5b.
Since magnetic flux is originally generated in the bobbin 3, when the coil 4 is energized, the bobbin 3 easily moves to the left without being restrained by any force, thereby driving the shutter blade.

SWA is a shutter open detection switch, and is composed of sections 8 and 9 and an insulating member 10. When the shutter is closed, the section 8 is curved by the protrusion 3a of the bobbin as shown in FIG. 1b, and the switch SWA is open, and when the shutter is slightly open, as shown in FIG. 1a, The switch SWA
is closed. The purpose of the switch SWA is to prevent the high magnetic permeability member 4a from detaching from the yokes 1a-1 and 1b-1 due to some kind of shock while the shutter is closed.
When the shutter starts to open, this is detected by the switch SWA, and the detection signal energizes the coil 4 to reset the bobbin 3 in the right direction, immediately closing the shutter. The system is designed to return to the normal state. Therefore, by installing the switch SWA, it is possible to prevent the shutter from malfunctioning due to a shock when the shutter is closed.

FIG. 2 is a diagram showing an embodiment of the structure of an electromagnetically driven slit exposure shutter according to the present invention, and shows a state in the initial stage of opening of the shutter. In the figure, 11 is the main plate, 12a to 1
2c is a leading shutter blade, 13a to 13c are shutter trailing blades, and 14a and 14b are leading blade driving arms, which are rotatable around a shaft (not shown) at the left end. Further, each of the arms is rotatably connected to the shutter leading blades 12a to 12c by shafts 16a to 16f. 15a and 15b are arms for driving rear blades, and these arms are rotatable around a shaft (not shown) at the left end. The arms each have rear shutter blades 13a to 13c and a shaft 17.
They are rotatably connected by a to 17f.

20 is an electromagnetic drive device shown in FIG. 1 for driving the shutter leading blade, and 21 is a similar electromagnetic driving device for driving the shutter trailing blade. 3b and 3
b' is a long groove provided in bobbin 3 and 3', respectively;
Pins 14b-1 and 15a-1, which are vertically erected on the leading blade driving arm 14b and the trailing blade driving arm 15a, are engaged with the long grooves, respectively, and by this engagement, the bobbins 3 and 3' The linear motion force is transmitted to the shutter leading blade and trailing blade, respectively. 22 is the shutter opening, and the state shown in FIG. 2 shows the shutter running state.

The drive circuit of the electromagnetic drive device (linear motor) used in the above embodiment is shown in FIG. 3a. This circuit is
Intended for use with an aperture-priority auto-exposure single-lens reflex camera with TTL aperture metering.

In the figure, 30 is a photovoltaic element (for example, SPC) that receives transmitted light from the photographic lens, and 31 is an operational amplifier (hereinafter abbreviated as OP amplifier) that constitutes the SPC head amplifier, with the SPC 30 connected to both input terminals. A diode 32 for logarithmic compression is also connected to the negative feedback path. 33 is a known arithmetic circuit, and 33' is the number of aperture stages of the preset aperture (△
AV) variable resistor for setting information; 34 is a variable resistor for setting ASA sensitivity information (S _V ) of the film used;
The arithmetic circuit 33 outputs information on the number of shutter speeds (T _v ) to be controlled. 3
6 is a capacitor for storing the T _v information, and 35 is a changeover switch which is normally connected to the a contact and changes to the b contact for the first time in conjunction with the start of the upward movement of the quick return mirror. 37 is an OP amplifier constituting a voltage follower, 38 is a logarithmic expansion transistor, and a time constant capacitor 38' is connected to its collector. 39 is a switching transistor for starting counting, 40 is an OP amplifier forming a comparison circuit, the non-inverting input of which is connected to the collector terminal of the extension transistor 38, and the reference voltage V _s is applied to the inverting input. has been done. 49 is a differentiation circuit connected to the output of the comparison circuit 40; 50 is a timer circuit;
It is triggered by a negative differential pulse and maintains a high level output for a certain period (for example, 20 mS). 52 is a differentiating circuit connected to the output of the timer 50. 45 is a normally open switch that closes when the quick return mirror completes its upward movement;
By closing this switch, a negative differential pulse is generated from the next stage differential circuit 46. Reference numeral 47 denotes a timer circuit connected to the output of the differentiating circuit 46, which is triggered by the negative differential pulse of the differentiating circuit 46 and maintains a high level output for a short period of time (for example, 2 mS). 46' is an RS flip-flop circuit,
Its set input is connected to the output of the differentiation circuit 46, and its Q output terminal is connected to a delay circuit 48. The output Q' of the delay circuit 48 is connected to the base of the counting start switching transistor 39 via a resistor. Reference numeral 53 denotes a timer circuit connected to the output of the differentiating circuit 52, which is triggered by a negative differential pulse from the differentiating circuit 52 and maintains a high level output for a certain period of time (for example, 20 mS).

51 is a timer circuit connected to the output of the differentiating circuit 49, which is triggered by a negative differential pulse from the differentiating circuit 49, and is activated for a short period of time (for example, 2 mS).
It maintains a high level.

55 is a two-input AND gate, one input of which is connected to the output of the RS flip-flop circuit 46', and the other input connected to the shutter open state detection switch SWA (for leading blade) connected in parallel. It is connected to the positive terminal V _cc of the power supply battery via the SWB and SWB (for the rear blade).

41 and 42 are power batteries connected in series, the connection point of which is grounded. MSW is the main switch of the camera, and the power terminal on the load side of the switch is named + _V'cc , and both terminals of the battery are named + _Vcc and _-Vcc .

Tr ₇ and Tr ₈ are switching transistors for driving the electromagnetic coils 6 and 6', respectively, and their bases are connected to the timer circuits 47 and 51 through resistors, respectively.
is connected to the output of Further, the coils 6 and 6' and current limiting resistors 43 and 44 are connected to the collectors, respectively.

54 is a two-input OR gate, one input of which is connected to the output _T4 of the timer circuit 53, and the other input connected to the output of the AND gate 55. 56
is an inverting circuit connected to the output of the OR gate 54.

Transistor Tr ₁ for driving electromagnetic coils 4, 4'
~Tr ₆ has a bridge configuration as shown in the figure. 4 is the second
Coil for driving the shutter leading blade shown in the figure, 4'
is a coil for driving the rear blade, and coil 4 connects the collectors of switching transistors Tr ₁ and Tr ₂ and Tr ₃ ,
Connected between the collectors of Tr ₄ . Further, the coil 4' is connected between the collectors of the switching transistors Tr ₁ and Tr ₂ and the collectors of the switching transistors Tr ₅ and Tr ₆ . In the figure, the direction of arrow A is the direction of current flow when the shutter is running, and arrow B
The direction of is the direction in which the current flows during shutter reset. The base of the switching transistor Tr ₁ is connected to the output of the RS flip-flop circuit 46', the base of Tr ₂ is connected to the output of the OR gate 54, the bases of Tr ₃ and Tr ₅ are connected to the output of the inversion circuit 56, and the base of Tr ₄ is connected to the output of the inverting circuit 56. The base is connected to the Q output of the RS flip-flop circuit 46', and the base of Tr ₆ is connected to the output T ₃ of the timer circuit 50 through resistors.

Reference numerals 57 to 60 represent constant current circuits, which are connected to the collector terminals of the switching transistors Tr ₃ to _{Tr 6} , respectively, and are configured to flow constant current in the forward and reverse directions of the leading blade coil 4 and the trailing blade coil 4'. ing. Further, the output currents of the constant current circuits 58 and 60 are set to be equal, so that the running speeds of the leading blade and the trailing blade when the shutter is running are the same.

The operation of this circuit configured as described above is shown in Figure 3b.
The explanation is based on the time chart.

At the output of the SPC head amplifier 30, a voltage corresponding to the subject brightness B _v and the aperture aperture A _vp of the photographic lens is generated, and this output voltage is applied to the next stage arithmetic circuit 33.
The aperture stage number information ΔAV of the preset aperture and the ASA sensitivity information S _v of the film used are calculated, and a voltage corresponding to the shutter speed information T _v to be controlled is generated at its output. The voltage is stored and held in a storage capacitor 36.

Next, when the shutter release operation is performed, the quick return mirror starts to move upward by means not shown, and the changeover switch 35 is connected to the b contact. Therefore, the storage voltage of the storage capacitor 36 is output as the output of the OP amplifier 37. When the upward movement of the quick return mirror is completed,
When the switch 45 is closed, a negative differential pulse is generated from the output of the differentiating circuit 46, which triggers the timer circuit 47, and its output remains at the H level for a short period of time, during which time the switching transistor _Tr7 is turned on, and the coil 6 shown in the second diagram is energized during that time. Therefore, as described in FIG. 1, the magnetization of the protrusions 1a-1 and 1b-1 of the yoke 1a is canceled, and the protrusions 1a-1 and 1b-1
Then, the attractive force of the high magnetic permeability member 4 disappears. Further, the RS flip-flop circuit 46' is set by a negative differential pulse from the differentiating circuit 46, and its Q output is inverted to H level and its output to L level. Therefore, the switching transistors Tr ₁ and Tr ₄ are turned on, and a constant current defined by the constant current circuit 58 flows in the direction of arrow A in the coil 4 of the leading blade.
The bobbin 3 in the figure starts moving leftward, and the shutter leading blade starts running.

Furthermore, the output Q of the flip-flop circuit 46'
Slightly later than the H level inversion of , the delay circuit 48
(The purpose of this is to compensate for the delay between the start of shutter leading blade travel and the start of exposure.) Output
Q' becomes H level and turns off the switching transistor 39 for starting counting. Therefore, the time constant capacitor 38' is connected to the OP amplifier 3.
It is charged by the logarithmically expanded current of the output voltage of No. 7, and its terminal level voltage JC decreases as shown in FIG. 3b. When this voltage JC becomes less than the inverted input voltage V _s of the OP amplifier 40 that constitutes the comparator circuit, the output OP of the OP amplifier 40 is inverted to L level, and a negative differential pulse is generated from the next stage differentiating circuit 49. Then, due to this pulse, the next stage timer 5 is activated.
1 is triggered, and its output T ₂ holds the H level for a short period of time (for example, for 2 mS). When the output T ₂ of the timer 51 becomes H level, the switching transistor Tr ₆ is turned on, and the coil 6' shown in FIG. 2 is energized. Therefore, as described above, the suction and holding force of the bobbin 4' disappears. Further, the timer 50 is also triggered by the negative differential pulse from the differentiating circuit 49, and its output _T3 is kept at the H level for a certain period of time (for example, 20 mS).
When the output _T3 of this timer 50 becomes H level, the switching transistor _Tr6 is turned on, and since the switching transistor _Tr1 is turned on as described above, the coil 4' of the shutter rear blade is connected to the arrow A.
A constant current defined by the constant current circuit 60 begins to flow in the direction of , and since the suction and holding force of the bobbin 4' has disappeared as described above, the trailing blade of the shutter begins to run. The time for which the output _T3 of the timer 50 is held at the H level is set to be slightly longer than the time required for the shutter trailing blade to complete travel, in order to ensure that the shutter trailing blade travel is completed.

When the output _T3 of the timer 50 returns to the L level, a negative differential pulse is generated from the next-stage differentiating circuit 52, and the RS flip-flop circuit 46' is reset by this pulse, and its Q output and output each become L level. Inverts to level and H level.
Also, since the output _T3 of the timer 50 is at L level,
Switching transistors Tr ₁ , Tr ₄ and Tr ₆ are turned off.

Further, the negative differential pulse from the differentiating circuit 52 triggers the next stage timer circuit 53, and its output _T4 maintains the H level for a certain period of time (for example, 20 mS). During this time, the output of the next-stage OR gate 54 is held at H level, and the output of the inversion circuit 56 is held at L level. Therefore, during that time, the switching transistors Tr ₂ , Tr ₃ and Tr ₅ are turned on, and the leading vane coil 4 is turned on.
and the rear blade coil 4' in the direction of arrow B, respectively.
A constant current defined by constant current circuits 57 and 59 flows, and the leading and trailing blades begin a reset movement. The time for which the output _T4 of the timer circuit 53 is held at H level is set to be slightly longer than the time for the shutter leading and trailing blades to complete resetting, in order to ensure that the reset is completed.

As explained above, in this circuit, when the shutter leading blade driving coil 4 and the trailing blade driving coil 4' start running, the coils 6 and 6' are energized for a short period of time, and during that time the yoke and bobbin During this time, the coil 4 or 4' on the bobbin side is energized to facilitate the running movement of the bobbin. Further, in this circuit, even after the shutter leading blade has been moved, the coil 4 continues to be energized until the reset operation is started, thereby preventing the shutter leading blade from returning due to a shock or the like.

Next, the opening prevention operation when the shutter is closed will be explained.

First, to explain the opening prevention operation of the shutter leading blade, in FIG. When the bobbin 3 moves to the left, the protrusion 3a of the bobbin 3 disengages from the section 8 of the switch SWA, and the switch SWA is closed as shown in FIG. 1a. Therefore, one input level of the AND gate 55 in FIG. The output of the OR gate 54 becomes H level, and the output of the inverting circuit 56 becomes L level. Therefore, switching transistors Tr ₂ and Tr ₃
and Tr ₅ are turned on, current flows in the reset direction (direction B) through the shutter leading blade coil 4 and the trailing blade coil 4', and the bobbin 3 receives a force in the right direction and moves to the right, so that the protruding part of the yoke 1a-1 and 1b-1
is again attracted to the highly permeable member 4 to maintain the shutter closed state.

In the case of the rear shutter blade, it operates in the same way using the switch SWB. By the way, during the operation of the shutter leading and trailing blades, the switch SWA
and SWB is closed, but at this time there is no need to flow current in opposite directions through the coils 4 and 4'. Therefore, while the shutter is running, the output of the RS flip-flop circuit 46' is at the L level, so the output of the AND gate 55 is at the L level regardless of the open/closed states of switches SWA and SWB. In some cases, the coils 4 and 4' are not energized in opposite directions.

As explained above, in the present invention, when it is detected that the movable element in the electromagnetic drive source that electromagnetically drives the shutter blade has moved from the travel end position at a time other than a release operation, the electromagnetic drive force is immediately used to return the mover to the original position. Since the shutter is returned to the travel end position, it is possible to provide an electromagnetic drive shutter that can prevent accidents such as erroneous exposure of the film.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of an electromagnetic drive device according to the present invention, in which FIG. 1a shows a state before the shutter blade holding means is in the holding state, and FIG. It is a figure which shows the state which held. FIG. 2 is a plan view showing an embodiment of the electromagnetically driven slit exposure shutter according to the present invention, and FIG.
3 is a circuit configuration diagram showing an embodiment of a driving circuit for an electromagnetic shutter according to the present invention, and FIG. 3b is a timing chart showing the operation of each part of the circuit of FIG. 3a. 1a, 1b, 1c...Yoke, 2a, 2b, 2
c, 2d...Permanent magnet, 3...Mover coil bobbin, 3a...Bobbin protrusion, 4...Movable coil, 1a-1, 1b-1...Yoke magnetic shunt protrusion, 5a, 5b... ...Magnetic gap, 6... Coil of magnetic shunt protrusion, 7... Magnetic gap of magnetic shunt,
8, 9, 10... Contact pieces that constitute the detection switch SWA.

Claims (1)

[Scope of Claims] 1. An electromagnetic drive source consisting of a movable element and a stator that move the shutter blades in two directions for exposure and return; a detection circuit that emits a signal representing a completed state when the child is located at the travel completion position and a signal representing the travel state when the child is located at an intermediate position; and a first signal that is generated in response to a release operation. a first drive circuit that drives the movable element of the electromagnetic drive source in the exposure direction based on a second signal generated after the exposure is completed; In the electromagnetic drive shutter, the electromagnetic drive shutter includes a second drive circuit that stops the drive based on switching from a signal representing the running state to a signal representing the completed state, wherein the mover has completed moving to the end position of the run. After the signal representing the completion state is emitted from the detection circuit, it is determined which signal, the first signal or the signal representing the running state, is emitted first, and the signal representing the running state is determined first. a determination circuit that generates a third signal when the determination circuit is issued; and a determination circuit that forcibly operates the second drive circuit in response to the third signal from the determination circuit to move the movable element in the return direction. An electromagnetic drive shutter characterized by being equipped with a control circuit for driving the shutter.