JPH0833569B2 - Sector switchgear - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a sector opening / closing device for a camera that utilizes contraction of a shape memory alloy as a driving force source.

[Conventional technology]

A sector opening / closing device for a camera using a so-called electrostrictive element as a driving force source, which has the property of being distorted / biased by applying a voltage and returning to its original shape by applying a reverse voltage or short-circuiting both terminals Have been proposed in the past.

An example of such a sector opening / closing device for a camera is shown in FIG. 10 (see Japanese Utility Model Laid-Open No. 64-34622).

In the drawing, reference numeral 101 is a substrate, which has an opening window 102 which is an optical path for photographing, is provided with elongated holes 101a and 101b, and a shaft 103 is erected. 104 is an electrostrictive element as a driving force source, which is distorted when a high voltage (several tens of volts to several hundreds of volts) is applied, and has the property of returning to its original shape by applying a reverse voltage to this or shorting both terminals. are doing.
Reference numeral 105 denotes a holding portion which holds the base portion fixed to the substrate 101 while allowing the tip portion of the electrostrictive element 104 to be freely distorted and biased.

An engaging arm 106 sandwiches and engages the tip portion of the electrostrictive element 104 and receives the biasing force of the element. 107 is a working arm, and the drive pins 107a and 107b are elongated holes 101a and 101 formed in the substrate 101.
It is planted so as to penetrate b.

Reference numeral 109 denotes a shutter blade that also serves as a diaphragm blade, which is rotatably supported by a shaft 103 and is engaged with a drive pin 107a of the working arm 107 by a long hole 109a so as to be driven. Reference numeral 111 denotes a second blade, which is rotatably supported by a shaft 103, is engaged with a drive pin 107b of the working arm 107 by a long hole 111a, and is driven by the first blade. Ten
The opening window 102 is opened and closed in cooperation with 9.

By tightening the connecting screw 108, the engaging arm 106 and the working arm 107 are subsequently operated integrally with the connecting screw 108 as a fulcrum.

When the shutter is released, a voltage is applied to the electrostrictive element 104 due to energization from a control circuit (not shown), and the element is distorted. Due to this distortion, the engaging arm 106 that engages with the distal end portion of the electrostrictive element 104 receives this bias, and the engaging arm 106 and the operating arm
107 rotates clockwise with the connecting screw 108 as a rotation spindle. The drive pin 107a installed on the working arm 107 of the operating lever,
107b act through the elongated holes 109a of the first blade 109 and the elongated hole 111a of the second blade 111, which are engaged with each other, in directions away from each other about the shaft 103, and open the opening window 102.

The moving amount (open angle) of the blade is detected by the through hole 109b formed in a part of the first blade 109 and the detection element 110,
When a predetermined time is reached due to the combination with the energization time, an instruction from a control circuit (not shown) causes a short circuit between both terminals of the electrostrictive element 104, and the electrostrictive element 104 instantly returns to its original shape.

[Problems to be Solved by the Invention]

However, in such a conventional sector opening / closing device, if an attempt is made to obtain a stroke required when opening / closing the shutter blades 109, 111, the electrostrictive element 104 cannot be made too small in terms of component accuracy. An enlarging mechanism such as the joint arm 106, the connecting screw 108, and the operating arm 107 was required.
In addition, the electrostrictive element 104 can only be formed in a flat plate shape due to its material, and cannot be bent around the opening window 102. Therefore, this device could not be made more compact.

Furthermore, in order to drive this device, the number 1
A high voltage of 0V to several 100V had to be applied. Therefore, the cost of the electric parts is increased, and it is necessary to take measures against electric shock to make the voltage high, and the cost of the entire device is high. In addition, the electrostrictive element 104 has a large width of hysteresis (residual strain does not return to the original state after application of voltage and after application), which complicates driving of the device and deteriorates responsiveness. Was there.

[Means for solving the problem]

In order to solve such a problem, according to the present invention, a sector provided on a base plate having an opening and biased in a direction to close the opening, and one end of which is supported by an operating portion of the sector, has a voltage A first shape memory alloy in the shape of a rope that changes the length by applying a force to operate the sector in the direction to open the opening, and the length is changed by applying a voltage with one end fixed to the base plate. A second shape memory alloy that changes to release the opening operation of the sector and rotates around a fixed shaft, and the other ends of the first and second shape memory alloys are sandwiched by the shaft. It is configured to include an intermediate mechanism for supporting.

[Action]

According to the sector opening / closing device having such a configuration, since the first and second shape memory alloys are provided, there is no need for an enlarging mechanism as in the conventional case, and the shape memory alloy can be freely changed according to the shape of the base plate. It can be configured in any shape. Therefore, this device can be made more compact.

Furthermore, the first and second shape memory alloys easily contract by applying a low voltage. Therefore, it is possible to reduce the cost of the electric component, and it is not necessary to take measures against electric shock as in the conventional case, so that the cost of the entire device can be reduced.

In addition, since the first and second shape memory alloys have a smaller hysteresis width than the conventional electrostrictive element, driving of this device is simple and responsiveness is improved. Further, the sector opening / closing device first applies a voltage to the first shape memory alloy to rapidly open the sector by utilizing the contracting force. next,
The voltage of the first shape memory alloy is turned off after a lapse of a predetermined time, and at this time, the voltage of the second shape memory alloy is applied and the contraction force is used to loosen the first shape memory alloy via the intermediate mechanism. The sector closes rapidly due to the spring force.
Therefore, this sector opening / closing device can increase the shutter opening / closing speed and can cope with a high-luminance object.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show a first sector opening / closing apparatus according to the present invention.
It is a figure showing an example.

First, in FIG. 1 for explaining the configuration, reference numeral 1 is a base plate, and a pair of shutter blades 4 and 5 (sectors) for opening and closing the shutter opening 2 are provided on the back surface side of the base plate 1. Has been done. The shutter blades 4 and 5 are rotatably supported at their base ends by fixed shafts 6 and 7 planted in the base plate 1, and elongated holes 8 and 9 are formed at the base ends thereof. ,Also,
It has the image edges 4a and 5a.

The sector pin 10 is inserted into the long holes 8 and 9 of the pair of shutter blades 4 and 5.
The sector pin 10 is fixedly mounted on a first drive lever 12 which is rotatably provided via a rotary shaft 11.
A cut groove 12a is formed in the first drive lever 12, and an eccentric adjustment pin 13 provided on the back surface side of a second drive lever 14 described later is fitted in the cut groove 12a. Further, the rotary shaft 11 supports a second drive lever 14 located on the front surface side of the base plate 1. Determining portions 14a and 14b are formed on the second drive lever 14, and a determining pin 15 is located between the determining portions 14a and 14b and fixed to the base plate 1. A pin 16 is fixedly mounted on the second drive lever 14, and the pin 16 is biased by a torsion coil spring 17 provided on the base plate 1.

The lead wire T1 is pulled out to the pin 16 and
One end of a first biometal 18 (trade name), which is a kind of shape memory alloy, is connected, and further, this biometal 18 is provided in an arc shape on the peripheral edge of the substantially disk-shaped base plate 1, as shown in FIG. First guide member 19 made of heat-resistant plastic, etc.
It is fitted in the groove portion 19a. The first biometal 1
The opening of the groove portion 19a is slightly narrower than the wire diameter of the biometal 18 so that the opening portion 8 does not come off from the groove portion 19a of the first guide member 19 when the sagging member 8 sags.

The other end of the first biometal 18 is connected to one arm portion 21a of a connecting member 21 that swings around a fixed shaft 20 planted in the base plate 1. Further, the other arm portion 21b of the connecting member 21 is always urged in the counterclockwise direction to connect the connecting member 21, and a tension spring having a spring force stronger than that of the torsion coil spring 17.
22 is installed. Further, the connecting member 21 is stopped by a stopper 23 implanted in the base plate 1. here,
The connecting member 21, the tension spring 22, and the stopper 23 constitute an intermediate mechanism as a whole.

In FIG. 1, the arm portion of the connecting member 21 with respect to the fixed shaft 20.
21a and 21b have the same length, but the first biometal 18
When the lengths of the second biometal 24 and the second biometal 24 (which will be described later) are different, the ratio of the lengths of the first biometal side arm portion 21a and the second biometal side arm portion 21b may be changed. For example, when the first biometal 18 is shorter than the second biometal 24, the length of the arm portion 21a on the first biometal side is shortened by the arm portion short 21b, and the second biometal 24 contracts to make the connecting member.
21 is rotated by the same length as the shrinkage of the first biometal 18.

One end of the second biometal 24 is attached to the arm portion 21b of the connecting member 21, and the second biometal 24 is further guided to the peripheral edge of the base plate 1 via the pulley 25 provided on the base plate 1. The groove portion 26a of the second guide member 26, which is provided substantially symmetrically with the member 19 and is also made of heat-resistant plastic or the like.
Has been inserted into. The other end of the second biometal 24 is a pin 27
This pin 27 is planted on an adjusting plate 29 provided on the base plate 1 via a screw 28, and a lead wire T2 is drawn out. By turning the adjusting plate 29 counterclockwise around the screw 28, the second biometal 24 is pulled so that it does not loosen. Further, the second drive lever 14 is urged counterclockwise in FIG. 1 by the urging force of the tension spring 22 via the connecting member 21 and the first biometal 18 (at this time, the shutter blades 4, 5 are shutters). Opening 2 is closed), 1st
I am pulling on Biometal 18 to prevent it from loosening.
The first and second biometals 18, 24 are electrically connected by the connecting member 21, and the lead wire T3 is pulled out from the connecting member 21. This lead wire T3 is
Since it is a common terminal for the first and second biometals 18 and 24, it may be connected to the base plate 1 and used as a ground.

In general, biometal has a property that its length shrinks by several percent when it is heated by applying a certain force (for example, spring force) (it may be self-heating by passing an electric current). Here, the amount of shrinkage varies depending on the temperature, but it becomes constant above a certain temperature. Therefore, after applying the voltage,
If F is set, the shutter can be opened and closed, and if the amount of contraction is kept constant by controlling the voltage (current), the diaphragm can be configured.

Further, in a small shutter, a change amount of about 3 to 5 mm is usually required to fully open the shutter blades, and when calculated backward, biometal needs to be about 100 mm in total length. Therefore, since the biometal is wire-shaped, its direction can be freely changed, and the biometal can be configured in any shape according to the shape of the base plate of the shutter (or diaphragm).

In addition, biometal can be driven even at low voltage. Since the electrical energy for driving the biometal has a VA value [W], it can be used at a low voltage by appropriately selecting the length and wire diameter of the biometal. For example, a biometal having a wire diameter of 0.15 mm and a length of 40 mm can be heated and driven at a voltage of 1 volt or less.

By the way, as shown in FIGS. 3 and 4, a guide member 31 made of heat-resistant plastic or the like is arranged around the periphery of the circular base plate 1 so as to surround it, and a groove portion of the guide member 31 is provided.
A sector opening / closing device in which the biometal 32 is fitted and attached to 31a is conceivable. Biometal 32
When a voltage is applied to both ends of the biometal 32, it heats up,
Shrink as a whole. When the biometal 32 contracts, the first and second drive levers 12 and 14 rotate clockwise, and a pair of shutter blades
Reference numerals 4 and 5 start opening the shutter opening 2. When the voltage application is stopped at the time when an appropriate exposure is obtained, the biometal 32 returns to the original state, and the biasing force of the torsion coil spring 17 is also applied to extend the biometal 32. When the biometal 32 extends, the first and second drive levers 12 and 14 rotate counterclockwise, and the shutter blades 4 and 5 close the shutter opening 2. Here, the biometal 32 has a property that it rapidly contracts when a voltage is applied, but it expands more slowly when the voltage is turned off than when it is applied. The rising edge is steep (shown by the solid line) and the falling edge is gentle (shown by the broken line). Further, since the biometal 32 contracts due to the heat generated by the voltage application, the temperature does not drop suddenly when the voltage is turned off, so there is a period (t1 in FIG. 5) in which the biometal 32 maintains the contracted state. Therefore,
Such a sector opening / closing device has a drawback in that the shutter opening / closing speed cannot be increased and it is not possible to deal with a high-brightness subject. However, the present invention also solves this drawback as described later. You can

 Next, the operation of the first embodiment will be described.

When no voltage is applied to the biometal 18, the second drive lever 14 is biased counterclockwise in FIG. 1 by the torsion coil spring 17, and the first drive lever 12 is rotated via the rotary shaft 11.
Is also biased counterclockwise. When the first drive lever 12 is biased counterclockwise, the sector pin 10 and the long holes 8 and 9 are formed.
The shutter blades 4 and 5 close the shutter opening 2 via.

Now, as shown in FIG. 6, the required opening time is calculated from the luminance signal, ISO signal and distance signal, and the P1 terminal (P1
When the terminal is normally at the Hi level) for a time t2, the voltage pulse V1 (shown in FIG. 7) is applied to the first biometal 18, so that the first biometal 18 contracts rapidly. . At this time, the tension spring 22 is the torsion coil spring 17
Since the connecting member 21 does not move, it is stronger than the second drive lever.
14 is rotated clockwise by the force of the torsion coil spring 17, and further the first drive lever 12 follows the shutter blades 4,
5 open.

When t2 time (shown in FIG. 7) has elapsed, the voltage pulse V1 is
Although it is turned off, if the P2 terminal of the control circuit (P2 terminal is normally Hi level) becomes Lo level at this point, the second
A voltage pulse V2 (shown in FIG. 7) is applied to the biometal 24, the second biometal 24 suddenly contracts against the tension spring 22, and the connecting member 21 rotates clockwise. Therefore, the first biometal 18 is pushed in the slackening direction (clockwise direction) as a whole, and the second biometal 18 is pushed by the force of the torsion coil spring 17 into the second biometal 18.
The drive lever 14 and the first drive lever 12 rotate counterclockwise, and the shutter blades 4 and 5 rapidly close as shown by the solid line in FIG. Therefore, this sector opening / closing device can increase the shutter opening / closing speed and can cope with a high-luminance object.

When the voltage pulse V1 is OFF, the first biometal 18
Begins to grow because no voltage is applied, but at this time the second
The second biometal 2 when the power of biometal 24 is turned off
4 extends and rotates the connecting member 21 in the counterclockwise direction and pulls the first biometal 18. Then, the shutter blades 4,5
However, since it starts to open again, the voltage is applied to the first biometal 18 until the first biometal 18 returns to its original state (t3 in FIG. 7). Also, the voltage is applied to the second biometal 24. Is the first biometal as shown by the alternate long and short dash line in FIG.
It may be started before the end of the voltage application to 18.

In this way, the voltage is applied to the biometal 18, and the amount of shrinkage is used to open and close the shutter blades 4, 5. Since the amount of shrinkage of the biometal 18 is considerably large as described above, an enlarging mechanism is not required as compared with the conventional example using the electrostrictive element. Further, since the biometal 18 is wire-shaped as described above, its direction can be freely changed, so that the biometal 18 can be formed into a free shape according to the shape of the base plate 1. Therefore, this device can be made more compact.

Further, in order to drive the device, as described above, only by applying a low voltage to the biometal 18, the biometal 18 easily contracts. Therefore, the cost of the electric parts can be reduced, and it is not necessary to take measures against electric shock as in the conventional case, and the cost of the entire device can be reduced.

In addition, since the biometal 18 has a smaller hysteresis width than the conventional electrostrictive element, the drive of this device is simple and the responsiveness is improved.

In addition, this sector opening / closing device is the first biometal
18 is applied a voltage, and the contraction force is used to make shutter blades 4,
Release 5 rapidly. Next, when a predetermined time elapses
The voltage of the biometal 18 is turned off. At this time, the voltage of the second biometal 24 is applied and the contraction force is used to loosen the first biometal 18 via the connecting member 21, so that the force of the torsion coil spring 17 The shutter blades 4 and 5 close rapidly. Therefore, this sector opening / closing device can increase the shutter opening / closing speed and can cope with a high-luminance object. On the other hand, as compared with the sector opening / closing device described in, for example, Japanese Utility Model Laid-Open No. 62-127530, since a step motor is not used, the step motor and the train wheel mechanism are unnecessary, and the entire device is made compact,
Cost reduction is possible.

Next, a second embodiment of the sector opening / closing device according to the present invention is shown in FIGS. 8 to 9 (a) and (b). In this embodiment, the same members as those in the previous embodiment are designated by the same reference numerals and the description thereof will be omitted.

First and second biometals 18, 24 in the first embodiment
Is short and a large opening amount at the shutter opening 2 cannot be obtained, the guide member 41 is provided around the periphery of the base plate 1 with a length close to the entire circumference, and FIG. , (B)
As shown in FIG. 5, the groove is partially formed in two steps 41a and 41b. The first biometal 18 has a groove 41 at the lower stage of the guide member 41.
It is fitted in a and has one end connected to the pin 16 and the other end connected to the arm portion 21a of the connecting member 21. The second biometal 24 is fitted into the groove 41b in the upper stage, and has one end connected to the pin 27 and the other end connected to the arm 21b of the connecting member 21 via the pulleys 42 and 43.

〔The invention's effect〕

As described above, according to the present invention, since the first and second shape memory alloys are provided, the expansion mechanism is not required unlike the conventional case, and the shape memory alloy can be freely changed according to the shape of the base plate. It can be configured in any shape. Therefore, this device can be made more compact.

Further, the first and second shape memory alloys easily contract by applying a low voltage. Therefore, it is possible to reduce the cost of the electric component, and it is not necessary to take measures against electric shock as in the conventional case, so that the cost of the entire device can be reduced.

In addition, since the first and second shape memory alloys have a smaller hysteresis width than the conventional electrostrictive element, driving of this device is simple and responsiveness is improved. Further, the sector opening / closing device first applies a voltage to the first shape memory alloy to rapidly open the sector by utilizing the contracting force. Next, when a predetermined time elapses, the voltage of the first shape memory alloy is turned off, and at this time, the voltage of the second shape memory alloy is applied and the contraction force is utilized to relax the first shape memory alloy through the intermediate mechanism. The sector will close quickly due to the spring force.
Therefore, this sector opening / closing device can increase the shutter opening / closing speed and can cope with a high-luminance object.

On the other hand, compared with the sector opening / closing device disclosed in Japanese Utility Model Laid-Open No. 62-127530, for example, a step motor is not used, so this step motor and train wheel mechanism are not required,
The entire device can be made compact and low cost.

[Brief description of drawings]

1 and 2 are views showing a first embodiment of a sector opening / closing device according to the present invention. FIG. 1 is a plan view of the first embodiment, and FIG. 2 is an AA line in FIG. FIG. 3 is a sectional view taken along the line, FIG. 3 and FIG. 4 are views showing another possible sector opening / closing device, FIG. 3 is a plan view of this device, FIG. 4 is a sectional view taken along line BB in FIG. FIG. 5 is a diagram showing an opening waveform of the shutter opening with time, and FIG. 6 is a control circuit of this device.
FIG. 7 is a diagram showing voltage application to the first and second shape memory alloys, FIGS. 8 to 9 are diagrams showing a second embodiment of the present invention, and FIG. 8 is a diagram showing this second embodiment. An example plan view, FIG. 9 (a) is a sectional view taken along line CC in FIG. 8, and FIG. 9 (b).
Is a partial side view of this guide member, and FIG. 10 is a plan view showing a conventional sector opening / closing device. 1 ... Base plate, 2 ... Opening 4,5 ... Sector 18 ... First shape memory alloy 24 ... Second shape memory alloy 21 ... Connecting member, 22 ... Tension spring 23 ... Stopper

Claims (1)

[Claims] 1. A sector provided on a base plate having an opening and urged in a direction to close the opening, and one end of which is supported by an operating portion of the sector so that a length thereof is changed by applying a voltage. A first shape memory alloy in the shape of a rope that actuates the sector in the direction to open the opening, and a first shape memory alloy that is fixed to the base plate at one end and changes in length by applying a voltage to release the opening operation of the sector. A sector opening / closing device comprising: a second shape memory alloy; and an intermediate mechanism that rotates around a fixed shaft and supports the other ends of the first and second shape memory alloys by sandwiching the shaft.