JP3352236B2 - Shutter device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera shutter device,
In particular, it relates to an electric shutter.

[0002]

2. Description of the Related Art A sector forming a lens aperture, a step motor for stepwise rotating in a forward or reverse direction in accordance with the phase sequence of a drive pulse supplied in time sequence, and transmitting the rotation of the step motor to the sector. A program shutter having a transmission train for controlling the opening and closing of the sector by controlling the rotation of the step motor is disclosed in Japanese Utility Model Publication No. 4-47697, Japanese Unexamined Patent Publication No. Hei 3-184029, and Japanese Utility Model Application Laid-Open No. 62-89624. No., JP-A-57-15
No. 0829, and the like.

[0003]

However, the stepping motor used in the prior art cannot generally increase the rotation speed at the start of driving and at the time of switching from forward rotation to reverse rotation. Can not be faster. Therefore, in order to obtain a high-speed shutter time, a half-open region of the aperture must be used.

Disadvantages when the object field can use only the half-bright area when the luminance is high are that the photographic lens cannot fully exhibit its original ability and that the interlocking distance of the flash is short at the time of daytime synchronization. And so on.

[0005] The applicant's application, Japanese Utility Model Publication No. 45-2
Japanese Patent Application Publication No. 6780 discloses a first shutter which is always closed, and a second shutter which is always open. The first shutter is opened and the second shutter is closed by energization, and the opening made by the first shutter is blocked by the second shutter. It has been proposed to determine the required exposure time by electrically controlling the operation start times of both.

However, in order to perform the high-speed shutter operation even in a region where the aperture is fully opened, it is necessary to increase the shutter speed itself. Variations in the time required for the shutter to operate become errors in the exposure amount. In particular, in the above-described conventional example, the driving source for driving the shutter is constituted by an electromagnet device. There is a drawback that the variation in the start of movement increases and the error in the exposure amount increases.

[0007]

In view of such problems,
According to the present invention, a first light-blocking member that changes the opening amount by movement, a first motor that drives the first light-shielding member from a fully open state to a fully closed state, and a second motor that changes the opening amount by movement are provided. A light shielding member, a second motor for driving the second light shielding member from a fully closed state to a fully open state, and control means for controlling driving of the first motor and the second motor,
The control means changes the driving speed of the first motor and the second motor according to the brightness of the subject,
A shutter capable of high-speed operation by maintaining a constant opening amount when the first light-shielding member and the second light-shielding member intersect while moving together and changing an exposure time. Can be provided, and at the same time, exposure suitable for a shooting situation can be performed.

[0008]

1 to 13 show a first embodiment of the present invention. FIG. 1 is a perspective view showing the relationship between components, and FIG. 2 is a sectional view.

1 is an upper base plate, 2 is a first drive ring,
An inner diameter portion 2a of the drive ring 2 is rotatably fitted to a cylindrical portion 1a formed at the center of the upper base plate 1. Drive pins 3 and 4 are fixed to the first drive ring. Reference numeral 5 denotes a first stepping motor, which is a first motor, and is a known stepping motor that can be indexed and rotated at a predetermined rotation angle. Reference numeral 6 denotes a first pinion which is fixed to the output shaft of the first stepping motor 5 and meshes with the gear shaft 2b of the first drive ring 2 to transmit the rotational driving force of the first stepping motor to the first drive ring 2. Reference numeral 7 denotes a first pressing plate, which is fixed to the top surface 1i of the cylindrical portion 1a after the first driving ring 2 is fitted to the cylindrical portion 1a as shown in FIG. 2, and prevents the first driving ring 2 from falling off. It is for.

Reference numeral 8 denotes a first shutter blade constituting a first light-shielding member.
And rotatably fitted in the hole 8a. A pin 8b is fixed to the first shutter blade 8, and the pin 8b is slidably fitted in the cam groove 1b of the upper base plate 1. Reference numeral 9 denotes a second shutter blade constituting a first light shielding member, and the above-mentioned drive pin 4 is rotatably fitted into the hole 9a through the elongated hole 1h of the upper base plate 1. The second shutter blade 9 has a pin 9
b is fixed, and the pin 9b is connected to the cam groove 1c of the upper base plate 1.
Is slidably fitted to

Reference numeral 10 denotes a blade retainer attached to the upper base plate 1 having an opening 10a and holding a gap between the upper base plate 1 and the first shutter blade 8 and the second shutter blade 9 in a plane direction. It is a board. Dowels 1f, 1 of upper base plate 1
d and 1e are protruding portions for providing the above-mentioned gap between the blade holding plate and the blade holding plate.

Reference numeral 11 denotes a base plate, and 12 denotes a second drive ring.
An inner diameter portion 12 a of the second drive ring 12 is rotatably fitted to a cylindrical portion 11 a formed at the center of the base plate 11. Drive pins 13 and 14 are fixed to the second drive ring. Reference numeral 15 denotes a second stepping motor, which is a second motor, and is a known stepping motor that can be indexed and rotated at a predetermined rotation angle. 16 is the second
The pinion is fixed to the output shaft of the second stepping motor 15, meshes with the gear portion 12 b of the second drive ring 12, and transmits the rotational driving force of the second stepping motor to the second drive ring 12. Reference numeral 17 denotes a second pressing plate, which is fixed to the top portion 11i of the cylindrical portion 11a after the second drive ring 12 is fitted to the cylindrical portion 11a as shown in FIG. belongs to.

Reference numeral 18 denotes a third shutter blade serving as a second light-shielding member.
It is rotatably fitted in the hole 18a through 1g. Third
A pin 18b is fixed to the shutter blade 18, and the pin 18b is slidably fitted in the cam groove 11b of the base plate 11.

Reference numeral 19 denotes a fourth shutter blade, which is a second light shielding member.
It is rotatably fitted to 19a through 1h. A pin 19b is fixed to the fourth shutter blade 19, and the pin 19b is slidably fitted in the cam groove 11c of the base plate 11.

The base plate 11 is attached to the blade holding plate 10 with a gap between the third shutter blade 18 and the fourth shutter blade 19 that can move in the plane direction between the base plate 11 and the blade holding plate 10. Tabs 11f, 11d, 1 of the base plate 11
Reference numeral 1e denotes a protruding portion for providing the above gap between the blade holding plate and the blade holding plate.

FIG. 3 is a sectional view taken along line AA in FIG.
FIG. 3 shows the first shutter blade 8 and the second shutter blade 9.
When the first drive ring 2 is rotated in the direction of arrow c from this state, the first shutter blade 8 and the second shutter blade 9 rotate around the optical axis. At this time, the pins 8b and 9b are connected to the cam grooves 1b and 1c, respectively.
The first shutter blade 8 according to the cam groove.
The second shutter blade 9 forms an opening while rotating around the hole 8a and the second shutter blade 9 around the hole 9a.

When the first step motor 5 is driven by one step, the first drive ring 2 is rotated by γ about the optical axis. The cam grooves 1b and 1c are such that the first drive ring 2 rotates by 3 · γ from the state shown in FIG. 3, that is, even if the first step motor is driven three steps, the first shutter blade 8 and the second shutter blade 9 The first shutter blade 8 and the second shutter blade 9 rotate around the optical axis in the subsequent steps of the first step motor 5 (shown in FIG. 4). At the same time, the cam grooves 1b, 1c are also centered on the holes 8a, 9a.
Rotated by The fourth step of the first step motor 5, that is, the fourth step from the initial position of the first drive ring 2
At the rotational position of γ, the opening composed of the first shutter blade and the second shutter blade becomes a pinhole (FIG. 5),
At the tenth step, that is, at the rotation position of 10.gamma. From the initial position of the first drive ring 2, the opening composed of the first shutter blade and the second shutter blade is fully opened. This state is shown in FIG.

In the subsequent steps, the first shutter blade 8 and the second shutter blade 9 do not rotate around the holes 8a and 9a and rotate with the first drive ring 2 around the optical axis while maintaining the fully opened state. Cam grooves 1b, 1c
Is composed. FIG. 7 shows the state of the twelfth step, which is the final rotation position of the first drive ring.

FIG. 8 shows the rotation angle θ about the holes 8a, 9a of the first shutter blade 8 and the second shutter blade 9 and the first rotation angle θ.
Is a graph showing the relationship between the step number of the stepping motor, when the rotation angle theta is theta _1, the shutter blade is pinholing, a fully open state when the theta _2.

FIG. 9 is a graph showing the characteristics of the stepping motor. When a drive electric signal is input so that the rotation speed of the stepping motor becomes, for example, a, the response does not instantaneously respond, but the speed of the stepping motor actually becomes the speed a. This indicates that a certain number of steps is required.

In this embodiment, the first stepping motor 4
Since the shutter is opened in the steps after the first step, the opening speed of the shutter has a very small error with respect to the speed set by the electric signal. Note that the specific number of steps does not limit the present invention.

As shown in FIG. 6, after the shutter blade is fully opened, the shutter blade is moved to a position 10 for determining the full opening.
In spite of the fact that the amount M that escapes from a is configured to be small, the actual final stroke is up to the twelfth step as shown in FIG. 7, so that the shutter blade is prevented from re-entering the position 10a for bouncing. There are advantages that can be done.

Note that the first shutter blade and the second
A sector device including a shutter blade, a first drive ring, and a first stepping motor will be referred to as a first sector device.

FIG. 10 is a sectional view taken along the line BB in FIG.

When the second drive ring 12 is driven in the direction of arrow D by the second stepping motor 15, the third shutter blade 18 and the fourth shutter blade 19 rotate about the optical axis, and simultaneously the holes are formed by the cam grooves 11b and 11c. It is also rotated about 18a and 19a. Third shutter blade 18,
FIG. 11 shows the relationship between the rotation angle α about the holes 18a and 19a of the fourth shutter blade 19 and the number of steps of the second step motor 15, and the second step motor 15 does not rotate until the second step, but from the third step. When the rotation angle reaches α ₃ at the ninth step, the rotation stops and the rotation stops around the optical axis until the 12th step. Rotation angle alpha ₁ third the total opening 10 _a in the figure, a rotation angle fourth shutter blade enters, alpha ₂ is the rotation angle as a pinhole.

A sector device including the third shutter blade, the fourth shutter blade, the second drive ring, the second stepping motor and the like will be called a second sector device.

Similarly to the first sector device, the second sector device controls the opening amount, that is, after the fourth step, the opening speed of the shutter blades has a very small difference between the set speed of the electric signal and the drive signal. , And 1 after 9 steps
Since the cam groove keeps the closed state up to two steps, it does not reopen even if it bounces at the twelfth step, which is the final step.

FIG. 12 is an electric circuit block diagram used in this embodiment. Reference numeral 101 denotes a control circuit for controlling the entire sequence of a microcomputer or the like; 102, a first step motor driving circuit for driving the first stepping motor 5; Reference numeral 103 denotes a second stepping motor driving circuit that drives the second stepping motor 15, and reference numeral 104 denotes a known photometry circuit that measures the luminance of the field.

The control circuit 101 shifts the first time by a time T based on the field luminance measured by the photometry circuit 104.
The first stepping motor 5 via the step motor driving circuit 102 and the second stepping motor driving circuit 103
The second stepping motor 15 is driven to rotate the first drive ring 2 and the second drive ring 12 in the directions of arrows C and D from the initial positions shown in FIGS. FIG. 13 shows that the opening amount (opening diameter) is a,
The opening amount (opening diameter) is indicated by b by the second sector device. The horizontal axis represents the time from the start of driving the first sector device and the number of steps of the first stepping motor and the second stepping motor. In the entire shutter device, a portion indicated by oblique lines is an opening area. The exposure amount can be changed by changing the delay time T.

When the exposure operation is completed, first, the first stepping motor 5 is rotated in the reverse direction to close the first sector device, and then the second stepping motor is rotated in the reverse direction to return to the fully open state shown in FIG. I will return. 14 to 17
FIG. 14 shows a second embodiment, and FIG. 14 is a block diagram of an electric circuit of this embodiment. Reference numeral 201 denotes a control circuit including a microcomputer or the like. The control circuit 201 makes a predetermined opening amount of the half-open area of the shutter constant, and changes only the TV value exposure time in accordance with the field luminance, that is, enables a programmable shutter in which the aperture value is prioritized.

At least the driving frequency of the first stepping motor of the first sector device is changed, and the driving start timing of the second sector device is adjusted so that the opening amount at the time of intersection with the shutter opening of the second sector device becomes constant. By changing it, it is possible to make the opening amount constant and change only the exposure time. FIG.
To FIG. 17 show some examples. The abscissa indicates the elapsed time from the time when the first sector device driving start time is set to 0, and the ordinate indicates the opening amount formed by the first and second sector devices. Sa _0, sa ₁ on the curve a, ..., sa ₁₂ points indicates the amount of opening of the first sector unit at each step of the first step motor, sb on the curve _{b 0, sb 1, sb 2} , ..., sb Reference numeral ₁₂ denotes an opening amount of the second sector device in each step of the second step motor.

In FIG. 15 to FIG. 17, L ₁ , L ₂ and L ₃ shown by oblique lines indicate the exposure amount of the shutter.

Considering the exposure amount L ₁ shown in FIG. 15, the driving frequency of the first and second stepping motors, and the delay time T ₁ of driving the second step motor with respect to the first step motor, FIG. time opening amount t _1/2 is S _1. FIG. 16 shows that the driving frequency of the first and second stepping motors is twice that of the one shown in FIG. 15, and the delay time T _{2 of the} start of driving the second step motor with respect to the first step motor is ＴT _1. since it is the effective exposure time as is clear from FIG t _2/2 is t _1/4, the opening amount is S _1, thus the exposure amount L ₂ is _{L 2 = (1/2) L 1} .

FIG. 17 shows that the driving frequency of the first and second stepping motors is 2/3 of that shown in FIG.
Since for the step motor is the delay time T ₃ of the driving start of the second stepping motor is (3/2) T _1, the effective exposure time t _3/2 As is clear from the figure (3/2) t _1, the opening The amount is S ₁ , and thus the exposure amount L ₃ is L ₃ = (3/2) L ₁ .

As described above, by changing the drive frequency of the step motor and the delay time at the start of driving the second step motor with respect to the first step motor, it is possible to change only the exposure time while keeping the aperture constant. .

FIG. 18 shows that the driving frequency of the first stepping motor is the same as that shown in FIG. 15, and the driving frequency of the second stepping motor is the same as that shown in FIG. 16, that is, twice that of FIG. is set to the driving frequency, the delay time T ₄ the opening amount is adjusted so that the S _1.

The effective exposure time t _4/2 at this time is (3 /
8) t ₁ next exposure amount L ₄ represents a _{L 4 = (3/4) L 1} .

FIG. 19 shows that the driving frequency of the first stepping motor is the same as that shown in FIG. 17, that is, the driving frequency is 2/3 times that of FIG. 15, and the driving frequency of the second stepping motor is shown in FIG. The driving frequency is set to be the same as that shown, that is, twice as high as that shown in FIG.
Delay time T ₅ the opening amount is adjusted so that the S _1.

The exposure time t _5/2 effective this time t _1/2
In the exposure amount L ₅ represents a L ₅ = L _1.

As described above, if the driving frequency of the first stepping motor and the driving frequency of the second stepping motor are set independently, the driving speed of each stepping motor can be set independently, and the same aperture and the same exposure Even if the amount is, the optimal shutter operation can be performed according to the shooting situation.

Further, even if the first and second stepping motors are intermittently driven and the pause time is changed, the driving speed can be substantially changed, and the present invention includes the contents thereof.

When manufacturing the shutter as described above, the loads for driving the first sector device and the second sector device do not always match, and the driving of the first step motor and the second step motor is not always performed. Since the outputs do not always match, it is necessary to set a drive frequency suitable for a slower sector device so as to prevent step-out during driving. Further, the relationship between the drive frequency and the drive load affects the start-up characteristics of the step motor, and also affects the exposure control accuracy.

For example, when the driving load is extremely small, the driving output of the stepping motor is high, and the driving frequency is low, the time from the start of driving to the target speed is repeatedly increased or decreased to converge on the target speed. May be applied. In order to quickly and stably approach the target speed, the drive frequency must be optimized for the drive load and the drive output of the step motor.

Therefore, the load when driving the sector device,
It is necessary to make the drive output of the step motor constant as much as possible or to take the following method.

The details will be described below in the third and fourth embodiments.

FIG. 20 and FIG. 21 are views for explaining the third embodiment, in which the first data storage means for storing the driving frequency data of the first step motor and the driving frequency data of the second step motor are stored. With the shutter device having the stored second data storage means, the drive data of the first step motor and the load of the first sector device are stored in the first data storage means to store the optimum drive frequency data. The first step motor is driven based thereon.

Further, the optimum driving frequency data is stored in the second data storage means with respect to the driving output of the second step motor and the load of the second sector device, and the second step motor is driven based thereon. To

FIG. 20 is a block diagram of an electric circuit used in this embodiment. Reference numeral 301 denotes a control circuit for controlling the entire sequence including a microcomputer and the like; 102, a first step motor driving circuit for driving the first stepping motor 5; Reference numeral 103 denotes a second step motor drive circuit that drives the second stepping motor 15, and reference numeral 104 denotes a known photometry circuit that performs photometry of the field luminance. 105 is a known clock circuit;
Reference numeral 7 denotes a memory A and a memory B which are data storage means composed of a rewritable nonvolatile memory such as an E ² PROM. The memory A is data storage means in which driving frequency data of the first step motor is stored, and the memory B
Is a data storage means in which drive frequency data of the second step motor is stored. The drive frequency data of the first step motor stored in the memory A is most stable and high speed according to the drive output of the first step motor and the load at the time of driving the first sector device when assembling the shutter device. The data is stored as data suitable for being driven by the user.

The drive frequency data of the second step motor stored in the memory B is most stable according to the drive output of the second step motor and the load at the time of driving the second sector device when assembling the shutter device. And is stored as data suitable for being driven at high speed.

A film feed motor 108 drives a known film feed gear train, a film feed motor driver circuit 109 drives a film feed motor 106,
Reference numeral 110 denotes a memory C, which is a data storage unit including a nonvolatile memory such as an E ² PROM.

The memory C has load characteristics of the first sector device,
The load characteristics of the second sector device, the driving characteristics of the first step motor, and the data of the delay time corresponding to the field luminance that changes depending on the driving characteristics of the second step motor are stored at the time of assembling the shutter device. I have. That is, a table of the delay time corresponding to the subject luminance is stored for each shutter device. An input unit 111 can input, for example, a shutter speed and an aperture value.

The control circuit 301 shifts by a time T based on the luminance of the field measured by the photometry circuit 104, and sends the first stepping motor and the second stepping via the first step motor driving circuit and the second step motor driving circuit. By driving the motor, the first drive ring 2 and the second drive ring 1
2 is rotated in the direction of arrows C and D from the initial position shown in FIGS. The details of the operation of the control circuit at that time are shown in FIG.
1 will be described later.

FIG. 13 shows the opening amount during the shutter exposure operation, in which the opening amount by the first sector device is shown by a and the opening amount by the second sector device is shown by b. The horizontal axis represents the time from the start of driving the first sector device and the number of steps of the first stepping motor and the second stepping motor. In the entire shutter device, the shaded portion is the area where exposure is actually performed. The exposure amount can be changed by changing the delay time T. When the exposure operation is completed, first, the first step motor is rotated in the reverse direction, the first sector device is closed, and then the second step motor is reversely rotated to return to the fully open state shown in FIG. 10, that is, the initial state.

The operation of the control circuit 301 will be described with reference to the flowchart of FIG.

(Step 1) It is determined whether or not a release switch (not shown) is turned on. If it is determined that the release switch is turned on, the process proceeds to step 2.

(Step 2) The photometry circuit 104 is operated to measure the brightness of the subject.

(Step 3) The data stored in the memory C is read out, and a delay time T corresponding to the brightness measured in Step 2 is determined in Step 2. The delay time T is used as a timer count-up time in step 10 described later.

(Step 4) The clock circuit 105 is reset.

(Step 5) From the data stored in the memory A, that is, the relationship between the drive output of the first step motor at the time of assembly and the load at the time of driving the first sector device,
The data stored as the most stable and high-speed driving frequency is read.

(Step 6) The first step motor 5 is driven via the first step motor drive circuit 102 to
The sector device starts driving in the direction from the state shown in FIG. 3 to the position shown in FIG. 7 according to the driving frequency data read in step 5.

(Step 7) The clock circuit 105 is started and the elapsed time from the start of driving the first step motor 5 is counted.

(Step 8) It is determined whether or not the first step motor 5 has been driven through the first step motor drive circuit 102 by a predetermined number of steps, that is, 12 steps in this embodiment as shown in FIG. If the step driving is completed, the process proceeds to step 9; if not completed, the process proceeds to step 10 while driving the first step motor 5 in a predetermined step.

(Step 9) The first step motor 5 is stopped via the first step motor drive circuit 102.

(Step 10) It is determined whether or not the count of the clock circuit 108 started in step 11 has reached the time determined in step 3, and if not, the flow returns to step 8 to reach. In this case, the process proceeds to Step 11.

(Step 11) The most stable and high-speed driving is possible from the relationship between the data stored in the memory B, that is, the driving output of the second step motor at the time of assembly and the load at the time of driving the second sector device. The data stored as the driving frequency is read.

(Step 12) The second step motor 15 is driven via the second step motor drive circuit 103,
The second sector device starts to be driven from the fully open state shown in FIG. 10 to the fully closed state according to the drive frequency data read in step 11.

(Step 13) The second stepping motor 15 is controlled by the second stepping motor driving circuit 103 to a predetermined number of steps, that is, as shown in FIG.
It is determined whether the two-step drive has been performed. If the drive in the predetermined step has been completed, the process proceeds to step 14, and if not, the process returns to step 8 while driving the second step motor 15 in the predetermined step. .

(Step 14) The second step motor 15 is stopped via the second step motor drive circuit 103.

(Step 15) The film feed motor 108 is driven via the film feed motor driver 109 to wind the next frame of the film.

(Step 16) The drive of the first step motor 5 is started at a predetermined drive frequency via the first step motor drive circuit 102 so that the first sector device enters the first state shown in FIG. I do. The driving frequency at this time may not depend on the data stored in the memory A.

(Step 17) The first step motor 5 is driven through the first step motor drive circuit 102 for a predetermined step to determine that the first sector device has reached the position shown in FIG. If so, go to step 18.

(Step 18) The first step motor 5 is stopped via the first step motor drive circuit 102.

(Step 19) If the second sector device is the one shown in FIG.
The second step motor drive circuit 10
The drive of the second step motor 15 is started at a predetermined drive frequency via the control unit 3. The driving frequency at this time is memory B
May not depend on the data stored in the.

(Step 20) The second step motor 15 is driven through the second step motor drive circuit 103 for a predetermined step to determine that the second sector device has reached the position shown in FIG. When the position is reached, the process proceeds to step 21.

(Step 21) The second step motor 15 is stopped via the second step motor drive circuit 103.

FIGS. 22 to 26 show a fourth embodiment, and FIG. 22 is a block diagram of an electric circuit of this embodiment. 401
Is a control circuit composed of a microcomputer or the like. Control circuit varies only exposure time in accordance with the subject field intensity by the area S ₁ with a half-open region of the shutter constant. That is, it enables a programmable shutter with an aperture value priority. The method will be described. The drive start timing of the second sector device is changed so that the drive frequency of at least one of the first and second stepping motors is changed and the opening area of the second sector device when crossing the shutter opening is constant. By changing it, the opening area can be kept constant and only the exposure time can be changed. 23 to 25 show some examples. The abscissa indicates the time at which the first sector device starts to be driven and is 0, and indicates the time elapsed since then. The ordinate indicates the opening area formed by the first and second sector devices. Sa ₀ , Sa on curve a
_1, ..., Sa ₁₂ points, S on the curve shows the opening area of the first sector unit at each step of the first step motor b
_{b 0, Sb 1, Sb 2} , ..., Sb 12 shows the opening area of the second sector device in each step of the second step motor.

In FIGS. 23 to 25, L indicated by oblique lines
₁ , L ₂ and L ₃ indicate the exposure amount of the shutter.

Considering the exposure amount L ₁ shown in FIG. 23, the drive frequency of the first and second step motors, and the delay time T ₁ of driving the second stepping motor with respect to the first step motor, FIG. The time

[0079]

[Outside 1] Maximum aperture area is it an S _1, Figure 24 is a first, driving frequency of the second stepping motor is compared to that shown in FIG. 23, twice and drive start delay time of the second step motor for the first step motor T ₂ is

[0080]

[Outside 2] As shown in the figure, the effective exposure time

[0081]

[Outside 3] Is

[0082]

[Outside 4] , The maximum opening area is S ₁ , thus

[0083]

[Outside 5] It is. FIG. 25 shows that the driving frequency of the first and second stepping motors is 2/3 of that shown in FIG. 23, and the delay time T _{3 of the} start of driving the second step motor with respect to the first step motor is

[0084]

[Outside 6] Therefore, as shown in the figure, the effective exposure time

[0085]

[Outside 7] Is

[0086]

[Outside 8] The maximum opening area is S ₁ and therefore

[0087]

[Outside 9] It is.

As described above, by changing the drive frequency of the first step motor and the second step motor and the delay time at the start of driving the second step motor with respect to the first step motor, only the exposure time can be maintained while the opening area is kept constant. Can be changed. Of course, even if the drive frequency of one of the step motors is not changed and the drive frequency of the other step motor and the delay time are changed, it is possible to perform exposure control that changes only the exposure time while keeping the opening area constant.

In FIG. 22, 202, 203, 204
The memory D, the memory E, which are data storage means composed of a rewriteable nonvolatile memory such as an E ² PROM,
Memory F. The memory D is data storage means in which drive frequency data of the first step motor is stored, and the memory E is data storage means in which drive frequency data of the second step motor is stored. The first stored in the memory D
The drive frequency data of the stepping motor is most stable at various opening speeds according to the driving output of the first stepping motor and the load at the time of driving the first sector device when assembling the shutter device. This is stored as appropriate data. In other words, in the device having the opening speed as shown in FIG. 23, the drive frequency data corresponding to each step for the most stable operation or the device having the opening speed as shown in FIG. Frequency data corresponding to each step for
8, the driving frequency for at least the first sector device to stably achieve various opening speeds, such as the driving frequency data corresponding to each step of the most stable operation. Data is stored in the memory D as a drive frequency data table in a number corresponding to the number of the opening speeds.

The driving frequency data of the first step motor stored in the memory E is stored in the second step motor when the shutter device is assembled.
It is suitable to be driven most stably at various opening speeds (in this case, the direction in which the shutter is closed) according to the drive output of the step motor and the load at the time of driving the second sector device. It is stored as data. In other words, the driving frequency data corresponding to each step for the most stable operation in the device having the opening speed as shown in FIG. 23, or the most stable operation in the device having the opening speed as shown in FIG. Therefore, at least the second sector device is stable, such as the drive frequency data corresponding to each step or the drive frequency data corresponding to each step for the most stable operation when the aperture speed is as shown in FIG. Driving frequency data for achieving various opening speeds is stored in the memory E as a driving frequency data table corresponding to the number of opening speeds.

Reference numeral 204 denotes a memory 3 which is a data storage means composed of a nonvolatile memory such as an E ² PROM.

The memory F stores the load characteristics of the first sector device, the load characteristics of the second sector device, the drive characteristics of the first step motor, and the field brightness that changes depending on the drive characteristics of the second step motor. Corresponding delay time is first
The number corresponding to the combination of the driving frequency of the step motor and the driving frequency of the second step motor is stored at the time of assembling the shutter device. That is, a table of delay time corresponding to the drive frequency of the first step motor, the drive frequency of the second step motor, and the field luminance is stored for each shutter device. An input unit 111 can input a shutter speed or an aperture value, for example.

The operation of the control circuit 401 will be described with reference to the flowchart of FIG.

(Step 201) It is determined whether or not a release button (not shown) has been pressed and a release switch (not shown) has been turned on.

(Step 202) The photometry circuit 104 is operated to measure the brightness of the subject.

(Step 203) Data stored in the memory F is read out, and a delay time corresponding to the brightness measured in Step 2 is determined. The delay time is used as a timer count-up time in step 10 described later. The delay time is read from the memory D in step 205 described later. The drive frequency data of the first step motor, which is also related to the drive frequency data of the second step motor read from the memory E in step 211 described later, and the brightness of the subject as described above with reference to FIGS. Is determined so as to keep the relationship such that the maximum opening area of the shutter does not change even if is changed.

(Step 204) The timer circuit 105 is reset.

(Step 205) The most stable driving is possible from the relationship between the data stored in the memory D, that is, the driving output of the first stepping motor at the time of assembly and the load at the time of driving the first selector device. From the data table stored as the driving frequency, data of the driving frequency that makes the opening speed corresponding to the subject luminance measured in step 202 is read.

(Step 206) The first step motor 5 is driven via the first step motor drive circuit 102,
The first sector device starts driving in the direction from the state shown in FIG. 3 to the position in the state shown in FIG. 7 according to the driving frequency data read in step 205.

(Step 207) The clock circuit 105 is started and the elapsed time from the start of driving the first step motor 5 is counted.

(Step 208) The first step motor 5 is driven through the first step motor drive circuit 102 by a predetermined number of steps, that is, as shown in FIG.
It is determined whether or not the step drive has been performed, and if the drive in the predetermined step is completed, the process proceeds to step 209. If not completed, the process proceeds to step 210 while driving the first step motor 5 in the predetermined step.

(Step 209) The first step motor 5 is stopped via the first step motor drive circuit 102.

(Step 210) The count of the clock circuit 108 started in Step 11 is incremented by Step 203.
It is determined whether or not the predetermined time has been reached. If the time has not been reached, the process returns to step 208, and if it has, the process proceeds to step 211.

(Step 211) The driving frequency at which the most stable driving can be performed based on the data stored in the memory B, that is, the relationship between the driving output of the second step motor at the time of assembly and the load at the time of driving the second sector device. Is read out of the data table stored as the data of the driving frequency that makes the opening speed according to the subject luminance measured in step 202.

(Step 212) The second stepping motor 15 is driven via the second stepping motor drive circuit 103, and the second sector device is read out in step 211 from the fully open state shown in FIG. 10 to the fully closed state. The driving is started according to the driving frequency data.

(Step 213) It is determined whether or not the second step motor 15 has been driven through the second step motor drive circuit 103 by a predetermined number of steps, ie, 12 steps in this embodiment as shown in FIG. If the driving of the step is completed, the process proceeds to step 214. If the driving is not completed, the process returns to step 208 while driving the second step motor 15 in a predetermined step.

(Step 214) The second step motor 15 is stopped via the second step motor drive circuit 103.

(Step 215) The film feed motor driver 109 is started. The film feed motor 108 is driven to wind the next frame of the film.

(Step 216) The first sector device is the one shown in FIG.
The drive of the first step motor 5 is started at a predetermined drive frequency via the first step motor drive circuit 102 so that the first state shown in FIG. The driving frequency at this time may not depend on the data stored in the memory A.

(Step 217) The first step motor 5 is driven through the first step motor drive circuit 102 for a predetermined step to determine that the first sector device has reached the position shown in FIG. If so, step 21
Proceed to 8.

(Step 218) The first step motor 5 is stopped via the first step motor drive circuit 102.

(Step 219) The second sector device is the one shown in FIG.
0 so that the state shown in FIG.
Via 03, the driving of the second step motor 15 is started at a predetermined drive frequency. The driving frequency at this time does not have to depend on the data stored in the memory B.

(Step 220) The second stepping motor 15 is driven through the second stepping motor driving circuit 103 for a predetermined step to determine that the second sector device has reached the position shown in FIG. When the position is reached, the process proceeds to step 221.

(Step 221) The second step motor 15 is stopped via the second step motor drive circuit 103.

[0115]

A first light-shielding member for changing the opening amount by movement, a first motor for driving the first light-shielding member from a fully open state to a fully closed state, and a second motor for changing the opening amount by movement. A light shielding member, a second motor for driving the second light shielding member from a fully closed state to a fully open state, and control means for controlling the driving of the first motor and the second motor. The control means changes the driving speed of the first motor and the second motor in accordance with the luminance of the subject, so that the first light-shielding member and the second light-shielding member intersect while moving together. By keeping the opening amount constant when the exposure is performed and changing the exposure time, it is possible to provide a shutter that can operate at high speed, and at the same time, it is possible to perform exposure suitable for a shooting situation.

[0116]

[0117]

[0118]

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a main part of a first embodiment of the present invention.

FIG. 2 is a sectional view of FIG.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a plan view of the sector device of FIG. 1, showing a state after the first stepping motor is driven by three steps;

5 is a plan view of the sector device shown in FIG. 1 and shows a state after the first stepping motor is driven by four steps.

FIG. 6 is a plan view of the sector device of FIG. 1, showing a state after the first stepping motor has been driven for 10 steps;

FIG. 7 is a plan view of the sector device of FIG. 1, showing a state after the first stepping motor is driven by 12 steps;

FIG. 8 is a diagram showing the relationship between the blade rotation angle of the sector device of FIG. 1 and the number of steps of a stepping motor.

FIG. 9 is a characteristic diagram of a stepping motor.

FIG. 10 is a sectional view taken along line BB of FIG. 2;

FIG. 11 is a diagram showing a relationship between the rotation angle of the second sector device blade in FIG. 1 and the number of steps of the stepping motor.

FIG. 12 is a block diagram of an electric circuit according to the first embodiment.

FIG. 13 is a diagram showing aperture characteristics of the second embodiment.

FIG. 14 is a block diagram of an electric circuit according to a second embodiment.

FIG. 15 is a diagram showing aperture characteristics of the second embodiment.

FIG. 16 is a diagram showing aperture characteristics of the second embodiment.

FIG. 17 is a diagram showing aperture characteristics of the second embodiment.

FIG. 18 is a diagram showing aperture characteristics when the driving frequencies of the first and second stepping motors are different.

FIG. 19 is a diagram illustrating aperture characteristics when the driving frequencies of the first and second stepping motors are different.

FIG. 20 is a block diagram of an electric circuit according to a third embodiment.

FIG. 21 is an operation flowchart of the third embodiment.

FIG. 22 is a block diagram of an electric circuit according to a fourth embodiment.

FIG. 23 is a diagram showing aperture characteristics of the fourth embodiment.

FIG. 24 is a diagram showing aperture characteristics of the fourth embodiment.

FIG. 25 is a diagram showing aperture characteristics of the fourth embodiment.

FIG. 26 is an operation flowchart of the fourth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper ground plate 2 1st drive ring 5 1st stepping motor 8 1st shutter blade 9 2nd shutter blade 11 Base plate 12 2nd drive ring 15 2nd stepping motor 18 3rd shutter blade 19 4th shutter blade 101,201, 301, 401 control circuit 102 first step motor drive circuit 103 second step motor drive circuit 106 memory B 107 memory A 110 memory C 202 memory D 203 memory E 204 memory F

Claims (1)

(57) [Claims] 1. A first light-blocking member for changing an opening amount by movement, a first motor for driving the first light-shielding member from a fully open state to a fully closed state, and a second motor for changing the opening amount by movement. A light shielding member, a second motor for driving the second light shielding member from a fully closed state to a fully open state, and control means for controlling the driving of the first motor and the second motor. The control means changes the driving speed of the first motor and the second motor in accordance with the luminance of the subject, so that the first light-shielding member and the second light-shielding member intersect while moving together. A shutter device characterized in that the opening amount at the time of the exposure is kept constant and the exposure time can be changed.