JP2002139771A - Focal plane shutter for camera and method for adjusting shutter speed - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a focal plane shutter for a camera constituted so that appropriate shutter speed or shutter speed near to the appropriate one is obtained even under high temperature or low temperature. SOLUTION: When the respective coils of an electromagnet for a front blade and an electromagnet for a rear blade are energized by the release of a camera, the iron core members 4 and 5 of the respective electromagnets attract and hold the iron piece member 8 of a front blade driving member 6 and the iron piece member 11 of a rear blade driving member 9. When a set member 12 is rotated clockwise thereafter, energizing of the respective coils is interrupted in order at a specified time interval, and the driving members 6 and 9 start operation in order, so that a front blade and a rear blade are made to perform exposing operation. In such a case, it happens that the appropriate shutter speed is not obtained under the high temperature or the low temperature though the specified appropriate shutter speed is obtained under normal temperature. In this case, the electromagnet is exchanged to perform 1st adjustment under the high temperature of the low temperature. Thereafter, 2nd adjustment is performed by changing timing to interrupt energizing under the normal temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focal plane shutter for a camera in which a front blade and a rear blade are sequentially actuated in the same direction during photographing, and exposure is performed by a slit formed therebetween. About.

[0002]

2. Description of the Related Art In many recent focal plane shutters, a leading blade and a trailing blade each comprising a plurality of arms and at least one blade are used. When an exposure operation is performed, an electromagnet for the leading blade and a trailing blade are used. When the energization to the electromagnets is sequentially cut off, the electromagnets are operated by the front blade driving member and the rear blade driving member whose holding force has been released directly or indirectly. The electromagnet for the front blade and the electromagnet for the rear blade each have a configuration in which a coil is wound around an iron core member having an attraction surface, and the driving member for the front blade and the driving member for the rear blade are respectively , And is driven by a driving spring for the front blade and a driving spring for the rear blade.

Also, before the next exposure operation is performed, the set member is operated from the initial position, and each drive member is operated to the set position. Thereafter, the set member is moved to the initial position. There are two types of known timings for returning, and there are two types, one for returning before the release operation is performed in the next photographing, and the other for returning after the release operation is performed. In the case of the former type, a member for locking each driving member at the set position is required, but such a member can be provided in the latter type depending on design specifications. ing.

In this type of focal plane shutter, a proper shutter speed (effective exposure time) can be obtained by adjusting the biasing force of the front blade driving spring and the rear blade driving spring during manufacturing. Designed. However, even if an appropriate shutter speed is obtained at room temperature, an appropriate shutter speed may not be obtained at high or low temperatures. That is, if the operating speed of the leading blade and the operating speed of the trailing blade change in the same manner even when the temperature changes extremely, the proper shutter speed is maintained, but in practice , A proper shutter speed may not be obtained.

[0005] The main causes of such a problem are that there is a difference in the change in frictional resistance due to a change in the shape of the members that are in sliding contact with each other, and that the above-mentioned driving members are lubricated. When oil is used, it is considered that the difference in viscosity change occurs. Therefore, in the related art, if it is found that such a situation occurs, the friction resistance of one of the leading blade system and the trailing blade system is increased, or the type of the lubricating oil is separated. I was trying to adjust. JP 2000-2907A
Japanese Patent Laid-Open Publication No. H11-15064 describes an example of measures related thereto.

[0006]

However, any of the adjustment methods performed as described above requires at least one of the operating speed (that is, the operating speed of at least one of the leading blade and the trailing blade).
This is performed by changing the slit forming edge of the slit forming blade (time during which the slit forming blade crosses the exposure opening). However, there are individual differences in the amount that changes at high and low temperatures with respect to the appropriate operating speed at normal temperature, so that the frictional resistance differs depending on those differences, and the type of lubricating oil It is very troublesome to adjust the operation speed so as to obtain an appropriate operation speed, for example, and it may be necessary to start over and over again. for that reason,
There is a demand for an adjustment method that requires less complicated work.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and it is an object of the present invention to produce a shutter having a proper shutter speed at room temperature. When the proper shutter speed cannot be obtained under low or low temperature, the proper or close to appropriate shutter speed can be obtained by adjusting the operation start timing without changing the operation speed of the front blade and the rear blade. An object of the present invention is to provide a focal plane shutter for a camera and a method of adjusting the shutter speed.

[0008]

In order to achieve the above object, a focal plane shutter for a camera according to the present invention comprises:
A leading blade and a trailing blade that are operated so that each slit forming edge crosses the exposure opening during the exposure operation; a leading blade driving member and a trailing blade driving member that individually operate the leading blade and the trailing blade during the exposure operation; Each of the coils connected in parallel to a separate capacitor is wound around each iron core member, and when the exposure operation is performed, the energization to the coils is cut off in sequence, so that the driving members for the front blade and the rear blade are driven. An electromagnet for the front blade and an electromagnet for the rear blade that enable the operation of the member,
And the front and rear blade electromagnets are configured to have different performances from each other.

According to another aspect of the present invention, there is provided a method of adjusting a shutter speed, comprising: a front blade and a rear blade which are operated so that each slit forming edge crosses an exposure opening during an exposure operation; A drive member for the front blade and a drive member for the rear blade that individually operate the front blade and the rear blade at the time of operation, and each coil connected in parallel to a separate capacitor is wound around each iron core member and exposed. A focal plane for a camera, comprising: an electromagnet for the front blade and an electromagnet for the rear blade that enable the operation of the driving member for the front blade and the driving member for the rear blade by sequentially stopping the energization of the coil during operation. When a predetermined shutter speed cannot be properly obtained under a high temperature or a low temperature in a shutter,
First, one of the electromagnets is replaced with an electromagnet having a different performance, and under the high or low temperature, the time interval when the two slit forming edges pass near the optical axis position,
The shutter speed is adjusted so as to be substantially the same as the case of the predetermined shutter speed, and then, at room temperature, the time when one of the two electromagnets is de-energized is changed, and the time interval is changed to the predetermined shutter speed. Adjust so that it is almost the same as in the case of.

Further, in the focal plane shutter for a camera or the method of adjusting the shutter speed according to the present invention,
The leading blade electromagnet and the trailing blade electromagnet may be configured such that their coils have different resistance values or their iron core members are made of materials having different magnetic permeability. It is suitable.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the illustrated embodiments. FIG. 1 is a plan view showing only a part of the left side when viewed from the subject side in a state where the shutter is set in a state where the shutter is set, and FIG. 2 is similar to FIG. FIG. 6 is a plan view of the state immediately after the end of the exposure operation as viewed from above. 3 to 6
Is an operating characteristic diagram for explaining the adjustment method when the operating speed of the rear blade changes under low temperature,
FIG. 3 is for explaining a change state at a low temperature, FIG. 4 is for explaining a first adjustment performed at a low temperature, and FIG. FIG. 6 is for explaining the second adjustment performed at room temperature and the result thereof. FIG. 7 is an explanatory diagram showing an example of a circuit configuration used in the electromagnet of the embodiment, and FIG. 8 is an explanatory diagram showing an attenuated state of a back electromotive voltage generated in the electromagnet.

First, the configuration of this embodiment will be described with reference to FIGS. 1 and 2. In the description, the subject side is referred to as the front side, and the image forming side is referred to as the back side. The shutter base plate 1 has an opening 1a formed in a substantially central portion of the shutter base plate 1 and having a horizontally long rectangular shape. However, as mentioned above, FIG.
2 shows only the left side of the shutter when viewed from the subject side.
Only the left part is shown. Although not shown, an intermediate plate and an auxiliary base plate are sequentially mounted on the rear side of the shutter base plate 1 at a predetermined interval, and the blades of the front blade are interposed between the shutter base plate 1 and the intermediate plate. Form a chamber,
A blade chamber of the rear blade is formed between the intermediate plate and the auxiliary base plate. An opening similar to the opening 1a is also formed in the intermediate plate and the auxiliary base plate. Usually, these three openings are overlapped to regulate the exposure opening. In the example, the description will be made assuming that the shape of the opening 1a regulates the exposure opening.

On the left side of the opening 1a, two arc-shaped long holes 1b and 1c are formed, and at the upper end thereof, a well-known buffer having a substantially C-shaped plane shape. Member 2,
3 is attached. Also, shafts 1d, 1e, 1f are erected on the front side of the shutter base plate 1, and on the rear side,
The shafts 1g, 1h, 1i, and 1j are erected, and among them, the shaft 1d and the shaft 1g, and the shaft 1e and the shaft 1i are arranged concentrically. A shutter base plate 1 is provided at the tip of the three shafts 1d, 1e, 1f standing on the front side.
A well-known support plate (not shown) is attached in such a manner as to be parallel to. Then, the electromagnet for the front blade and the electromagnet for the rear blade are attached to the support plate in accordance with the method described in JP-A-9-133944. Iron core member 4,
Only 5 is indicated by a dashed line. Further, as can be seen from the above-mentioned publication, the iron core members 4 and 5 are actually U-shaped, and a coil wound around a bobbin is fitted to one of the two magnetic pole portions. I am wearing it. As is well known, as shown in FIG. 7, capacitors C1 and C2 are connected to the coils L1 and L2.

A drive member 6 for the leading blade is rotatably mounted on the shaft 1d of the shutter base plate 1. The front blade drive member 6 is made of a synthetic resin, and has a roller 6a and a drive pin 6b on the back side, and a mounting portion 6c on the front side. Among them, the drive pin 6b
The bottom of the shutter base plate abuts against the cushioning member 2, and the front end portion penetrates the elongated hole 1 b and protrudes to the rear side of the shutter base plate 1. Further, the mounting portion 6c is formed so as to protrude toward the front surface side, and a well-known iron piece member 8 is mounted inside with a compression spring 7 interposed therebetween, as shown in a partial cross section. I have. Although not shown, a driving spring for the front blade is hung on the driving member 6 for the front blade to urge the driving member 6 for the front blade to rotate in the counterclockwise direction. The biasing force can be adjusted in a known manner.

A drive member 9 for the rear blade is rotatably mounted on the shaft 1e of the shutter base plate 1. The rear blade drive member 9 is also made of a synthetic resin, and includes a pressed portion 9a,
It has a drive pin 9b and a mounting portion 9c. And
Among them, the drive pin 9b is provided on the back side, the root portion can be brought into contact with the buffer member 3, and the tip portion penetrates through the elongated hole 1c and protrudes to the back side of the shutter base plate 1. ing. Further, an iron piece member 11 is mounted inside the mounting portion 9c with a compression spring 10 interposed in the same manner as in the case of the mounting portion 6c. Further, a rear blade drive spring (not shown) is also hung on the rear blade drive member 9 to urge the rear blade drive member 9 to rotate in the counterclockwise direction. Powers can also be adjusted in a known manner.

A set member 12 made of synthetic resin is rotatably mounted on the shaft 1f of the shutter base plate 1. The set member 12 is urged to rotate clockwise by an urging force of a return spring (not shown), but the rotation is prevented by a stopper (not shown) in FIG. Hereinafter, this position of the set member 12 will be referred to as an initial position. In addition, the set member 12 includes pressing portions 12a and 12b,
When the counterclockwise rotation in FIG. 2 is performed, the pressing member 12a is driven by the leading blade driving member 6.
, And the pushing portion 12b pushes the pushed portion 9a of the rear blade drive member 9.

Next, the structure of the front blade and the rear blade disposed on the back side of the shutter base plate 1 will be described. First, the leading blade is composed of two arms 13, 14 rotatably attached to the shaft 1g and the shaft 1h, and a plurality of blades pivotally supported in order toward their tips. ing.
However, since the specific pivot structure is well known, in this embodiment, only the slit forming blades 15 pivotally supported at the foremost portions of the arms 13 and 14 are shown in order to make the drawing easy to see. ing. The drive pin 6b is fitted in the long hole 13a formed in the arm 13. On the other hand, the rear blade is composed of two arms 16, 17 rotatably attached to the shafts 1i and 1j, and a plurality of blades pivotally supported in order toward their tips. However, in this embodiment, the arms 16 and 17
Only the slit forming blade 18 pivotally supported at the foremost portion of FIG. The long hole 16a formed in the arm 16
Is fitted with the drive pin 9b.

Next, the operation of this embodiment will be described. FIG.
Indicates a set state of the shutter. In this state, the pushed member 12c of the set member 12 is suppressed by a member (not shown) on the camera body side, and is prevented from rotating clockwise by the urging force of a not-shown return spring. Accordingly, the roller 6a is suppressed by the pushing portion 12a of the set member 12, and the leading blade driving member 6 is prevented from rotating counterclockwise by the urging force of the not-shown leading blade driving spring. ing. At this time, the iron piece member 8 is compressed by the compression spring 7 and pressed against the iron core member 4 of the electromagnet for the front blade.
A plurality of blades are deployed to cover the opening 1a. On the other hand, the rear blade driving member 9 is
The pushed portion 9a is suppressed by 2b, and is prevented from rotating counterclockwise by the urging force of the rear blade drive spring (not shown). At this time, the iron piece 11
Is pressed against the iron core member 5 of the electromagnet for the rear blade by compressing the compression spring 10, and the rear blade is stored at a position below the opening 1a with a plurality of blades superimposed.

When the release button of the camera is pressed in such a set state, first, current is supplied to the coils L1, L2 of the respective electromagnets from the DC constant voltage power supply, and the iron piece members 8, 11 are connected to the iron core members 4, 5, respectively. Adsorbed and held. These energizations are actually performed via an electronic circuit, but in FIG. 7, they are replaced by switches SW1 and SW2. Next, since a member (not shown) on the camera body side releases the restraining force of the set member 12 against the pushed portion 12c, the set member 12 is moved clockwise by the urging force of the not-shown return spring. It rotates and returns to the initial position. Then, first, the coil L of the electromagnet for the first blade
When the power supply to the first member 1 is cut off (SW1 is turned off), the attraction force of the iron core member 4 with respect to the iron piece member 8 is lost, and the leading blade driving member 6 is actuated by the biasing force of the leading blade driving spring (not shown). Rapidly rotated counterclockwise. As a result, the drive pin 6b rotates the arm 13 in the counterclockwise direction, so that the plurality of blades of the leading blade move upward, and the opening 1a is opened by the slit forming edge (lower edge) of the slit forming blade 15. To go.

After a lapse of a predetermined time after the current supply to the coil L1 of the front blade electromagnet is cut off, the current supply to the coil of the rear blade electromagnet is cut off (SW2 is turned off). Therefore, the suction force of the iron core member 5 to the iron piece member 11 is lost, and the rear blade drive member 9 is rapidly rotated counterclockwise by the urging force of the rear blade drive spring (not shown). At that time, the driving pin 9b rotates the arm 16 in the counterclockwise direction, so that the plurality of rear blades start moving upward while reducing the overlapping amount, and the slit forming edge (upper end) of the slit forming blade 18 is formed. Edge 1a
Cover. Therefore, at that stage, a slit is formed by the slit forming blade 15 of the front blade and the slit forming blade 18 of the rear blade, and the image forming surface is continuously exposed. Then, when the slit forming blade 15 of the front blade completely retreats upward from the opening 1a, the driving member 6 for the front blade stops when the driving pin 6b abuts on the buffer member 2, and then the rear blade Drive member 9 has a plurality of rear blades having an opening 1.
When the drive pin 9b is completely covered, the drive pin 9b comes into contact with the buffer member 3 and stops. FIG. 2 shows a state in which the exposure operation has been completed in this way.

The setting operation of this embodiment is performed by rotating a set member 12 in a counterclockwise direction by a member (not shown) on the camera body side. That is, when the member on the camera body side pushes the pushed portion 12c of the set member 12 and rotates counterclockwise against the urging force of the return spring (not shown), first, the pushing portion of the set member 12 is pressed. 12a pushes the roller 6a of the leading blade driving member 6, and rotates the leading blade driving member 6 clockwise against the urging force of the leading blade driving spring. At this time, the driving pin 6b of the front blade driving member 6 rotates the arm 13 clockwise, so that the plurality of blades of the front blade move downward while being deployed.

Thereafter, the slit forming blade 15 of the leading blade is formed.
When the overlapping amount of the rear blade and the slit forming blade 18 reaches a predetermined amount, the pressing portion 12b of the set member 12 presses the pressed portion 9a, and the rear blade driving member 9 is rotated clockwise. Go. Therefore, the driving pin 9b rotates the arm 16 in the clockwise direction, so that the plurality of rear blades are moved downward while increasing the overlapping amount. Then, after that, the iron piece members 8, 1 attached to the respective drive members 6, 9
When 1 contacts the iron core members 4 and 5 of each electromagnet, the rotation of the set member 12 is stopped immediately thereafter. The stopped state is the set state shown in FIG.
Is maintained until the next photographing is performed.

In the exposure operation performed as described above, the operating speed of the front blade and the rear blade is substantially adjusted by adjusting the urging force of the drive spring for the front blade and the drive spring for the rear blade (not shown). If they are operated at a predetermined timing, it is possible to obtain an appropriate predetermined shutter speed that does not cause uneven exposure. This
More specifically, referring to FIG. 3, the slit forming blades 15 and 18 (strictly speaking, their slit forming edges) of the front blade and the rear blade operate as indicated by solid lines A and A. In this case, the operation time required for the opening 1a from the lower side position to the upper side position is the same, and the imaging surface is located at the center position of the opening 1a (when viewed from the front blade and the rear blade,
This means that the exposure is continuously performed at the same time as the time interval (time A) at the time when a part of each slit forming edge passes near the optical axis). In this case, the shutter speed (effective exposure time) is A time, and FIG.
The number of graduations is 10.

However, at the time of manufacture, even if the shutter is manufactured so that an appropriate shutter speed can be obtained at room temperature, an appropriate shutter speed may not be obtained at high or low temperature. In general, such a situation is more likely to occur at low temperatures than at high temperatures. Therefore, an example in which an appropriate shutter speed cannot be obtained at a low temperature will be described. As described above, the solid lines A and A in FIG. 3 indicate a case where the shutter is manufactured so that an appropriate shutter speed can be obtained at room temperature. When this shutter is operated in an environment of, for example, −20 degrees, the internal resistance value of the coil of each electromagnet and the capacity of each capacitor become small, and each of the driving members 6, 9
The start time of the operation becomes slightly earlier.

That is, when the temperature becomes low, the resistance of the coils L1 and L2 of each electromagnet becomes smaller than at room temperature, so that the back electromotive force generated when each blade operates is also large. However, since the capacitances of the capacitors C1 and C2 also become smaller, their back electromotive force is consumed by the respective electromagnets, and the respective capacitors C1 and C2 are charged earlier by a time constant smaller than that at normal temperature. As a result, the time from when the exposure operation start signal is output to when the iron piece members 8 and 11 are actually released from the iron core members 4 and 5 is slightly shortened. In the exponentially attenuated waveform shown in FIG. 8, the time T2 from when the switch is turned off to when the iron pieces 8, 11 are released is the time T1 at normal temperature. It can be understood from the fact that it is shorter.

In FIG. 8, the dashed line shows the waveform at room temperature, and the solid line shows the waveform at a low temperature of -20 degrees. The voltage level at the start of operation is shown. Further, in this embodiment, since the characteristic change of the iron core members 4 and 5 due to the temperature change is extremely small, the effect of the temperature is substantially the same as the coil L1 and the coil L1.
This appears in the resistance value of L2 and the capacitance of capacitors C1 and C2. From this, at low temperatures, the operation of the slit forming blades 15 and 18 is as indicated by broken lines b and b, respectively, and the operation start time is only one scale earlier, respectively. An appropriate shutter speed can be obtained.

However, as already described, when the temperature is lowered to about −20 degrees, the leading blade and the trailing blade are changed due to a change in frictional resistance in each sliding portion and a change in mechanical properties such as a change in viscosity of lubricating oil. Will cause a difference in the operation time. Actually, there are various forms of the difference, but here, in order to make the following explanation of the adjustment process easy to understand, the operation of the front blade is performed by the resistance value of the coil L1 and the capacitor C1. The operation of the rear blade is affected not only by the change in the resistance of the coil L2 and the capacity of the capacitor C2, but also by the above-mentioned frictional resistance and the change in the viscosity of the lubricating oil. The case will be described. In FIG. 3, an example of the operating state of the slit forming blade 18 of the rear blade, in which the mechanical properties have changed in this manner, is indicated by a chain line C. As a result, the slit forming blades 15,
The number of interval scales at 18 is 13 at the center position and 14 at the upper side position, so that the shutter speed is obviously reduced and exposure unevenness is caused.

Therefore, in the following, when such a situation occurs, in the present invention, what steps and what means are used for adjustment will be described.
First, the adjustment step will be described as an order. A broken line B shown in FIG. 4 indicates an operating state of the slit forming blade 15 of the leading blade at a low temperature shown in FIG. The dashed line C indicates the operating state of the slit-forming blade 18 of the rear blade whose mechanical properties have changed under the low temperature shown in FIG. In the present invention, in such a case, the operation start timing is advanced without changing the operation speed of the rear blade, that is, the operation time of the slit forming blade 18, and the opening 1a
Is adjusted so that the above-mentioned time A can be obtained at the center position of. This is the adjustment of the first step. The two-dot chain line d in FIG. 4 shows the operating state after the adjustment as described above.

After adjusting the first step at a low temperature in this manner, it is operated at a normal temperature. FIG. 5 shows an operation state at that time.
The operation of the slit forming blade 15 of the front blade naturally returns from the state shown by the broken line B to the state shown by the solid line A. Also, at this time, the operation of the slit forming blade 18 of the rear blade changes from the two-dot chain line d after the adjustment at the low temperature, and is like a three-dot chain line E. Therefore, the time difference between the slit forming blades 15 and 18 at the center position of the opening 1a is slightly shorter than the time A, and the time A '(9 scales and 1
(Between 0 scales). Therefore, in the case of the present invention, the adjustment of the second step is performed at room temperature, and the circuit for controlling the electromagnet (exposure time control circuit) is adjusted to adjust the timing of starting the operation of the slit forming blade 18. A little later, the above A 'time becomes A time.

FIG. 6 illustrates the operation of the slit forming blades 15, 18 after the two adjustment operations have been completed as described above. The three-dot chain line E indicates the operating state of the slit forming blade 18 at room temperature, and the two-dot chain line D indicates the operating state at a low temperature of -20 degrees. In addition, the dashed-dotted line c is the -20 of the slit forming blade 18 before adjustment, for comparison with the dashed-dotted line d.
5 shows an operation state at a low temperature. Therefore, as can be seen from FIG. 6, at room temperature, the initial appropriate shutter speed is substantially obtained. Further, at a low temperature of -20 degrees, since the one-dot chain line c before the adjustment has changed to the two-dot chain line d, the amount of change from the appropriate shutter speed is less than half in the visual calculation using the scale.
Note that it is needless to say that the adjustment operation performed in this manner is preferably performed at the shutter speed (the maximum speed) having the smallest slit width.

Next, a description will be given of the means for performing the adjustment in the first step. As can be understood from the description of FIG. 3, the coils L1 and L2 and the capacitors C1 and C2 used in the electromagnet (see FIG. 7).
Changes in their properties due to changes in environmental temperature,
As a result, the operation start timing of each of the driving members 6 and 9 changes. On the other hand, the adjustment in the first step is the slit forming blade 1
The operation start timing of 8, ie, the operation start timing of the rear blade drive member 9 is changed. As can be seen from this, if the initial electromagnet for the rear blade is replaced with another electromagnet for the rear blade configured so that the operation start time of the driving member 9 for the rear blade is different even when the energization is cut off at the same time. , Can be adjusted. As described above, each electromagnet of the present embodiment includes the iron core members 4 and 5 and the coils L1 and L2 wound therearound.

Therefore, first, consider the coil. The coil has a smaller resistance value as the wire diameter increases. Also, the resistance value decreases as the number of turns around the iron core member decreases. Therefore, as described with reference to FIG. 4 described above, in order to speed up the start of the operation of the slit forming blade 18 of the rear blade, the resistance value of the coil may be reduced, and the wire diameter is larger than the initial electromagnet coil. Prepare an electromagnet in which several types of coils are wound by the same number, and replace them by selecting from them, or use several types of coils with the same wire diameter as the original electromagnet but with a small number of turns. What is necessary is to prepare an electromagnet and replace it with one that can be adjusted most appropriately. Alternatively, several types of electromagnets equivalent to the above may be prepared by changing the coil diameter and the number of turns, and may be replaced with an appropriate one.

Further, it is possible to prepare several types of electromagnets equivalent to the above by changing the wire material of the coil, and to select an appropriate one from them. In this case, as a wire material, a soft copper wire is most often used, and in addition, there are a copper alloy wire, an aluminum wire, an aluminum alloy wire, and the like. Among the copper alloy wires, there are a cadmium copper wire, a copper tin alloy wire, a silicon copper wire, a cadmium copper wire containing silver, and the like. Even if the same wire is used, different types of electromagnets can be prepared by applying different insulating coatings. However, considering the manufacturing, it is necessary to prepare several types of electromagnets using the same wire and the same wire diameter and changing only the number of turns, and replace them with the one that can be adjusted most appropriately. Is practical.

On the other hand, consider an iron core member which forms an electromagnet together with a coil. Even when the energization of the electromagnet is cut off at the same time as described above, if the magnetic permeability of the iron core member is different, the operation start time of the drive member changes. Therefore, it is also possible to prepare a plurality of electromagnets in which iron core members are made of materials having different magnetization characteristics, and to select and adjust the most appropriate electromagnet from among them. In this case, nickel-iron alloys and pure iron are used as the material of the iron core member often used in this technical field. Among the nickel-iron alloys, permalloy (PB, PB,
PC, PE).

The adjustment described with reference to FIGS.
Although the case where the operation start timing of the rear blade is changed with reference to the front blade is performed, the present invention may change the operation start timing of the front blade with reference to the rear blade.
In the step adjustment, the starting time of the operation of the leading blade is changed,
The step adjustment may be performed by changing the operation start timing of both, such as changing the operation start timing of the rear blade. However, it is not very practical to make adjustments by changing the operation start timing of both. Further, in the above description, the case where the shutter speed is lower than the appropriate speed at a low temperature has been described. However, the present invention can of course be applied to the case where the shutter speed is higher at a high temperature. is there.

Also, as is well known, the focal plane shutter has a direct type in which each driving member is directly held by the attraction force of each electromagnet immediately before the start of the exposure operation, and a holding member which is held by a locking member. There is known a locking type in which a holding electromagnet releases its holding. The above embodiment is directed to a direct type shutter, but the present invention can also be applied to a locking type shutter. Further, among focal plane shutters, there is known a shutter referred to as a double light-shielding type in which both a front blade and a rear blade cover an exposure opening in a set state. Is
The present invention can be applied to a shutter having such a configuration. Further, the present invention can be applied to both a film-based camera and a digital camera.

[0037]

As described above, according to the present invention, an appropriate shutter speed cannot be obtained at a high temperature or a low temperature even though the shutter is manufactured so as to obtain an appropriate shutter speed at a normal temperature. By changing the electromagnet and adjusting the start time of operation without changing the operation speed of the front blade or the rear blade, it is possible to obtain a proper or close to proper shutter speed.

[Brief description of the drawings]

FIG. 1 is a plan view of an embodiment showing only a part on the left side when viewed from an object side in a state where the shutter is set in a state in which the shutter is set in a state in which the shutter is set in the camera.

FIG. 2 is a plan view of the embodiment shown in the same manner as FIG. 1 and shows a state immediately after an exposure operation is completed.

FIG. 3 is an operation characteristic diagram for explaining an adjustment method in a case where the operating speed of the rear blade changes at a low temperature in the embodiment, and shows a state changed at a low temperature.

FIG. 4 is an operation characteristic diagram for explaining a first adjustment performed at a low temperature based on the state shown in FIG. 3;

FIG. 5 is an operation characteristic diagram for explaining what state is under normal temperature after the first adjustment.

FIG. 6 is an operation characteristic diagram for explaining a second adjustment performed at a normal temperature and a result of the second adjustment.

FIG. 7 is an explanatory diagram showing an example of a circuit configuration used for the electromagnet of the embodiment.

FIG. 8 is an explanatory diagram showing a decay state of a back electromotive voltage generated in the electromagnet.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shutter base plate 1a Openings 1b, 1c, 13a, 16a Slots 1d, 1e, 1f, 1g, 1h, 1i, 1j Shaft 2, 3 Buffer member 4, 5 Iron core member 6 Driving member for leading blade 6a Roller 6b, 9b Drive pins 6c, 9c Attachment part 7,10 Compression spring 8,11 Iron piece member 9 Rear blade drive member 9a, 12c Pushed part 12 Set member 12a, 12b Pushed part 13,14,16,17 Arm 15, 18 Slit forming blade L1, L2 Coil C1, C2 Capacitor SW1, SW2 Switch

Claims (4)

[Claims] 1. A front blade and a rear blade which are operated so that each slit forming edge crosses an exposure opening during an exposure operation, and a front blade driving member and a rear member which individually operate the front blade and the rear blade during an exposure operation. The blade driving member and the respective coils connected in parallel to the separate capacitors are wound around the respective iron core members, and when the exposure operation is performed, the energization to the coils is cut off in order, so that the leading blade driving member And a front blade electromagnet and a rear blade electromagnet that enable the operation of the rear blade driving member, and the front blade electromagnet and the rear blade electromagnet are configured to have different performances from each other. A focal plane shutter for a camera. 2. A front blade and a rear blade that are operated so that each slit forming edge crosses an exposure opening during an exposure operation, and a front blade driving member and a rear blade that individually operate the front blade and the rear blade during an exposure operation. The blade driving member and the respective coils connected in parallel to the separate capacitors are wound around the respective iron core members, and when the exposure operation is performed, the energization to the coils is cut off in order, so that the leading blade driving member And a front-plane electromagnet that enables the operation of the rear-blade driving member and the rear-blade electromagnet, a predetermined shutter speed cannot be properly obtained at high or low temperature in a camera focal plane shutter. First, when one of the electromagnets is replaced with an electromagnet having a different performance, and under the high or low temperature, when the two slit forming edges pass near the optical axis position. Is adjusted to be substantially the same as in the case of the predetermined shutter speed, and then, at room temperature, change the timing at which the energization of one of the two electromagnets is stopped, and change the time interval. A method of adjusting a shutter speed, characterized in that the shutter speed is adjusted to be substantially the same as in the case of the predetermined shutter speed. 3. The electromagnet for a front blade and the electromagnet for a rear blade,
The focal plane shutter for a camera or the method of adjusting the shutter speed according to claim 1 or 2, wherein the coils are configured to have different resistance values. 4. The electromagnet for the front blade and the electromagnet for the rear blade,
3. The focal plane shutter for a camera or the method of adjusting the shutter speed according to claim 1, wherein the iron core members are made of materials having different magnetic permeability.