JPH0695205A - Diaphragm controller - Google Patents

Abstract

PURPOSE:To attain a light-weighted and miniaturized controller whose structure is simple and whose cost is reduced by releasing energizing a stepping motor in order to eliminate useless current consumption of a camera and also maintaining a stop in an open state by using the stepping motor without always detecting the open state of the stop and also without installing a mechanism for locking the stepping motor. CONSTITUTION:The controller is provided with the stepping motor 1, plural aperture blades 5, stop driving members 4 and 6 for opening/closing the aperture blades 5 by the driving force transmitted from the stepping motor 1, a fixed aperture 6b for deciding the aperture diameter of the stop, a detecting means 7 for detecting that the aperture blades 5 are positioned on a prescribed position where the opening diameter of the aperture blade 5 is larger than the aperture diameter of the aperture 6b and a control means for stopping the operation of the stepping motor 1 after detecting by the detecting means that the aperture blades reach the prescribed position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm control device, and more particularly to a diaphragm control device which maintains a diaphragm open state and performs a diaphragming operation by using a stepping motor.

[0002]

2. Description of the Related Art Conventionally, a diaphragm mechanism of a camera has to keep the diaphragm open during distance measurement and photometry. Even in the diaphragm mechanism using the stepping motor, the opening state must be maintained. Therefore, a means for energizing the stepping motor to maintain the opening state of the diaphragm has been adopted. However, if the stepping motor is energized, current consumption will be wasted and the life of the battery built into the camera will be shortened. For this reason,
The stepping motor is de-energized so that the self-holding force of the stepping motor maintains the open state. However, compared to the holding force when the stepping motor is energized, the self-holding force when deenergized is weak, so if vibration and strong external force are applied to the camera, the stepping motor will move and the diaphragm will open. Can no longer be maintained.

Therefore, as disclosed in Japanese Unexamined Patent Publication No. 58-90624, an aperture open state detection means for detecting the aperture open state is provided to open the aperture and deenergize the stepping motor. Therefore, when the camera moves due to vibration or strong external force that cannot maintain the open state, the open state detection means detects that the aperture has been narrowed down, and the stepping motor A means of resuming energization, returning the aperture to the open state, and then deenergizing the stepping motor. Alternatively, as disclosed in Japanese Patent Laid-Open No. 58-90627, an aperture open state detection means for detecting the aperture open state and a stepping motor lock means for locking the stepping motor when the aperture is open. When the aperture is opened, the aperture open state detection means detects the aperture open state, and the stepping motor lock means mechanically locks the stepping motor to maintain the aperture open state. To release the power to the stepping motor and release the mechanical lock of the stepping motor at the start of the release operation.
There has been proposed a means of restarting energization to the stepping motor to narrow down the diaphragm.

[0004]

However, the above-mentioned conventional means have the following problems. That is, in the one disclosed in Japanese Patent Laid-Open No. 58-90624, the power supply to the stepping motor is released in order to save the current consumption of the camera, but the aperture open state detection means always detects the aperture open state. It has the drawback of having to
Further, in the one disclosed in JP-A-58-90627, the power supply to the stepping motor is released, but a mechanical means for locking the stepping motor must be newly provided, which complicates the structure. There is a problem that the shape becomes large and the cost increases.

An object of the present invention is to solve the above problems and
Aperture that uses a stepping motor without turning on the power to the stepping motor in order to reduce the consumption of camera current, without constantly detecting the open state of the aperture, and without providing a mechanism to lock the stepping motor. It is an object of the present invention to provide an aperture control device that maintains the open state of the above, has a simple structure, is lightweight and compact, and is low in cost.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a stepping motor, a plurality of diaphragm blades, a diaphragm driving member for transmitting a driving force from the stepping motor to cause the diaphragm blades to open and close, and a diaphragm aperture diameter. A fixed aperture that determines that the aperture diameter of the aperture blade is at a predetermined position that is larger than the aperture diameter of the aperture, and the opening operation of the aperture blade by driving the stepping motor. In carrying out, it is characterized by comprising control means for stopping the operation of the stepping motor after detecting that the predetermined position has been reached by the detection means.

[0007]

The diaphragm driving member is driven by the driving force from the stepping motor to open and close the diaphragm blade, and when the diaphragm blade is opened, the diaphragm blade is placed at a predetermined position that is larger than the diaphragm aperture diameter of the fixed aperture. When it reaches, the detection means detects this, and the control means stops the operation of the stepping motor by this detection.

[0008]

The present invention will be described below with reference to the illustrated embodiments. FIG. 1 is an exploded perspective view of a diaphragm mechanism in a diaphragm control device showing an embodiment of the present invention. The stepping motor 1 is fixed to a part of the rear surface of the lens frame 3 with a screw, and a pinion gear 2 is fixed to the output shaft of the motor 1. The front of the lens frame 3 is provided with the arrow wheel 4,
A diaphragm mechanism including the diaphragm blades 5 and the diaphragm cam plate 6 is attached. The lens frame 3 is provided with a through hole 3a in which the pinion gear 2 is rotatably arranged. The front surface of the lens frame 3 is a diaphragm driving member rotatably arranged. The pinion gear 2 meshes with a drive gear (not shown) provided in a part of the arrow wheel 4. Then, a stopper projection 4a protruding rearward is fitted in a part of the rear surface of the arrow wheel 4 into a stopper cam groove 3b (not shown) formed in a part of the lens frame (see FIG. 3), The range of rotation of the arrow wheel 4 is limited.

On the front surface of the arrow wheel 4, there are six support shafts 4b, which are the centers of rotation of the diaphragm blades 5, at the six equidistant positions. In this embodiment, the diaphragm blade 5 is composed of six blades. Therefore, a fulcrum hole 5a formed in the base of each diaphragm blade 5 is rotatably and tightly fitted to the support shaft 4b. In addition, in FIG. 1 above,
Only one diaphragm blade 5 is shown, and the remaining five are not shown. A drive pin 5b projects toward the front at a position on the front side of each aperture blade 5 in the middle and outward, and the drive pin 5b is formed in the aperture cam plate 6 through a cam groove hole 6a. Is fitted to. The cam groove holes 6a are formed in the doughnut-shaped disk at six positions at equal intervals on the diaphragm cam plate 6. One end of each of the cam groove holes 6 a is located at the center opening of the cam plate 6, and the other end thereof is at the cam plate 6.
An outer peripheral edge portion of the linear inclined cam groove hole 6a1 is formed in a crocodile and a short linear cam groove hole 6a2 that is connected to the other end and is inclined slightly outward. Further, the diaphragm cam plate 6 forming the diaphragm driving member is fixed to the lens frame 1 from the front with screws, and also forms a lid of the diaphragm mechanism.

The aperture cam plate 6 has a central opening formed in a fixed aperture (mask) 6b having an aperture opening diameter. Therefore, when the stepping motor 1 rotates the arrow wheel 4, each diaphragm blade 5 performs a narrowing operation along each cam groove hole 6 a of the diaphragm cam plate 6. Further, the arrow wheel 4 is provided with a cutout portion 4c at a part of its outer peripheral edge portion. Further, a detection piece 4d bent in an L shape is arranged near the cutout portion 4c on the rear surface of the arrow wheel 4. The detection piece 4d is for switching the switch of the photo interrupter (PI) 7 arranged in the lens frame 3 at a position where the diaphragm blade 5 is opened by two steps from the diaphragm opening aperture. The PI 7 is operated by the piece 4d to detect the position of the diaphragm blade 5. That is, the horizontal portion of the detection piece 4d is arranged parallel to the back surface of the arrow wheel 4 and rotates together with the arrow wheel 4 to block the light flux of the PI. The stepping motor 1 and the PI 7 are connected by a flexible printed circuit board 8 to a diaphragm drive circuit (not shown).

Next, the operation of the diaphragm mechanism in the diaphragm control device of the above-described embodiment having the above structure will be described. When the stepping motor 1 is rotationally driven step by step, the pinion gear 2 of the stepping motor 1 is rotated step by step, and the arrow wheel 4 is rotated step by step. The support shaft 4b of the arrow wheel 4 also rotates together with the diaphragm blade 5 by the rotation of each step. Then, the drive pin 5b of the diaphragm blade 5 is moved to the lens frame 3
Since the diaphragm blade 5 moves along the cam groove hole 6a of the diaphragm cam plate 6 fixed to, the diaphragm blade 5 is rotated around the support shaft 4b to perform a step-by-step drawing operation or an opening operation. . The arrow wheel 4 has the stopper projection 4a.
Is restricted in the range in which it moves by fitting into the stopper cam groove 3b. Further, the PI 7 detects the position of the detection piece 4d, and the output of the PI 7 is switched from ON to OFF at the position where the diaphragm blade 5 is opened by two steps from the opening diameter.

2 and 3 are front views of the main part of the diaphragm mechanism of the diaphragm control device. FIG. 2 shows six diaphragm blades 5.
3 shows the arrangement of members related thereto, and FIG. 3 shows the arrangement of members other than the diaphragm blade 5. In FIG. 2, the position of the diaphragm blade 5 shown by the solid line shows the position of the diaphragm opening aperture, and the position of the diaphragm blade 5 shown by the chain double-dashed line shows a state in which the aperture is larger than the aperture opening aperture. Is shown. The above-mentioned cam groove hole 6a2 is provided in the above-mentioned diaphragm cam groove hole 6a for further opening the diaphragm blade from the position of the diaphragm blade at the opening diameter (fixed aperture diameter).
Is provided, and the shape of the cam 6a is formed in the cam groove as described above so that the camera is not easily narrowed down to the opening diameter even if vibration or a strong external force is applied to the camera when the energization to the stepping motor 1 is released. It is formed by the holes 6a1 and 6a2.

Next, the operation when the diaphragm blade 5 is in the diaphragm open state will be described with reference to FIG. This Figure 4
The relationship between the number of steps of the stepping motor 1 and the timing of the change of the diaphragm (AV) by the diaphragm blades and the timing of PI7 which is a position detecting device of the diaphragm blades 5 is shown.
In the above diaphragm mechanism, when the stepping motor 1 is rotated to open the diaphragm, the diaphragm blades 5 reach the fixed aperture 6b of the cam plate 6, and the diaphragm opening position (aperture 6b) opens the diaphragm. Move to.
Then, in the state in which it is opened by two steps, the PI 7 which is a position detecting device for the diaphragm blade 5 is operated by the detection piece 4d and is switched from ON to OFF. As a result, next, the position where the diaphragm blade 5 is opened by one step is set as the initial position,
As the stop position of the stepping motor 1, the power supply to the stepping motor 1 is released. Then, the diaphragm blade 5 is held by the self-holding force of the stepping motor 1 itself, thereby eliminating waste of current consumption.

When the diaphragm blades 5 are stopped in this way, even if vibration or a strong external force is applied to the camera, there is a margin of 3 steps up to the diaphragm opening aperture, so that distance measurement and photometry are not adversely affected. It is possible to realize a small, lightweight and low-cost diaphragm mechanism without requiring a special lock mechanism for the stepping motor 1.

However, when the stepping motor 1 is moved due to vibration or strong external force applied to the camera, if the narrowing-down operation is started in that state, the initial position of the narrowing-down shifts, so that the exposure accuracy at the time of narrowing-down is improved. descend. In order to solve the deterioration of the exposure accuracy, the excitation state of the stepping motor at the initial position is written in the EEPROM at the time of diaphragm adjustment, and the excitation state written in the EEPROM is energized at the time of the diaphragm narrowing operation, and the diaphragm blade position detecting means is provided. Looking at the state of the signal of PI7, if it is in the off state, the aperture narrowing operation is performed, and if it is in the on state, it is driven once to return to the initial position, and then the aperture narrowing operation is performed to secure the exposure accuracy.

Regarding the position detection of the diaphragm blades, in this embodiment, the detection piece 4d arranged on the arrow wheel 4 by the PI 7 is used.
However, it is also possible to detect the position by providing holes in the gear train or the blades, or to detect the position by the pattern of the substrate and the contact piece.

FIG. 5 is a block diagram showing the overall construction of an aperture control device including the aperture mechanism of the above embodiment. A start signal from the start means 11 is input to a microcomputer (μCOM) 12 which is a control means, a data signal from the photometry calculation circuit 13 is input to the μCOM 12, and a data signal from the aperture setting means 14 is the μC.
Input to OM12. Further, the data from the μCOM 12 is stored in the EEPROM 15, and the EEPROM 1
The same data stored in 5 is read into the μCOM 12. A 4-bit data signal of P0, P1, P2, P3 is input from the μCOM 12 to the driver circuit 16,
A drive signal of the stepping motor is input to the stepping motor 1 from the driver circuit 16. The stepping motor 1 rotates the arrow wheel 4. The rotation position of the arrow wheel 4 is detected by the detection piece 4d provided on the arrow wheel 4 as a PI.
7 detects and this detection signal is input to the μCOM 12.

The operation of the diaphragm control device thus constructed will be described with reference to the flow charts and relational diagrams shown in FIGS. 6, 7, 8 and 9. FIG. 6 shows a flowchart of the narrowing drive. In step S1, the narrowing sequence starts, and the process proceeds to step S2. In step S2, when the start signal from the start means 11 is input to the μCOM 12, the data signals from the photometric calculation circuit 13 and the aperture setting means 14 are input to the μCOM 12, and as described later, The initial position data and the narrowing offset adjustment value data stored in the EEPROM 15 are read out to the μCOM 12. Then, the process proceeds to step S3. In step S3, the photometric calculation circuit 13 and aperture setting means 14
An appropriate aperture step number is calculated and determined based on the information from the above and the aperture adjustment value from the EEPROM 15 and according to the camera mode at that time. Then, the process proceeds to step S4. In step S4, the PI 7 is operated to detect the open position of the diaphragm, and the process proceeds to step S5.

In step S5, the above step S2
The initial position data read in step 4 is output to the driver circuit 16 as 4-bit data, and the driver circuit 1
At step 6, the stepping motor 1 is initially excited and the arrow wheel 4 rotates. Here, the stepping motor 1 has two exciting coils and four terminals. To excite the stepping motor 1, the μCOM1
The two outputs P0, P1, P2, P3 to the above driver circuit are shown in (1), (2), (3) and (4) below.
The driver circuit 16 is configured by a transistor bridge so that the remaining two bits of the i (high) level and the remaining two bits are output as a Lo (low) level signal and are changed in the following order, so that the driver circuit 16 can be narrowed down or opened. Has been done. Then, the process proceeds to step S6.

(1) (2) (3) (4) P0 Hi Lo Lo Hi P1 Hi Hi Lo Lo P2 Lo Hi Hi Lo Lo P3 Lo Lo Hi Hi ―――――――― →→ Refine ← ―――― In the opening step S6, if the output of the PI7 is confirmed and the aperture is displaced from the opening initial position and the output of the PI7 is on, the process proceeds to step S7, and the opening of the opening will be described later with reference to FIG. Accurate narrowing down is performed by performing a sequence and performing opening drive to the initial position. In this embodiment, as described above, the stepping motor 1 has four excitation states M1, M2, M3 and M4. For example, in FIG.
If the excited state at the initial position set in the adjustment sequence described later (see FIG. 9) is M1, then the excited state at the moment when the diaphragm blade is narrowed down from the aperture is also M1. When the stepping motor 1 is not energized and moves up to M4 of X immediately before opening due to vibration or the like, the next step of initial excitation causes the stepping motor 1 to move to M of Y.
Although it moves to 1, if the output of PI7 is confirmed and turned on, the diaphragm operation is performed after returning to the initial position of M1 of Z, so the diaphragm accuracy is improved. Therefore, step S
Go to 8.

Returning to step S6, if the PI 7 is not turned on, it is determined that the diaphragm blade 5 is at the initial position, and the process proceeds to step S8. In step S8, an interval time T1 until the next one step is set is set, and the process proceeds to step S9. In step S9, step 9 is repeated until t = T1, and after the set time T1 has elapsed, the process proceeds to step S10. In step S10, the stepping motor 1 is excited to the state of the next step, and the stepping motor 1 narrows down by one step to perform step S11.
Proceed to. If it is determined in step S11 that the number of aperture steps set in step S3 has not been completed, step S8 is performed in order to perform one-step aperture reduction again.
Return to. If all the aperture steps have been completed in step S11, the process proceeds to step S12, and the refinement sequence ends.

FIG. 8 shows a sequence of opening drive of the diaphragm. In step S21, the opening sequence starts and the process proceeds to step S22. In step S22,
Similar to the narrowing-down flowchart described above, the EEP
The opening initial position data is read from the ROM 15 and the process proceeds to step S23. In step S23, the PI 7 is operated to detect the open position of the diaphragm.
Go to 4. In step S24, the RA having the excitation state at the final stop position in the narrowing drive in the μCOM 12 is set.
Based on the narrowing-down data stored in M, narrowing-down initial excitation is performed, the diaphragm is narrowed down, and the process proceeds to step 25.

In step S25, an interval time T2 until the aperture moves to the next one step opening is set, and the process proceeds to step S26. In step S26, t = T
Repeat step S26 until 2 is reached, and set time T
After 2 has passed, the process proceeds to step S27. Step S27
In step 1, the stepping motor 1 is excited to the state of the next step, and the stepping motor 1 is driven to open for one step. The excitation state here changes in the order of opening as opposed to narrowing down. Then, the process proceeds to step S28.

In step S28, the above step 2
The excitation state data updated in step 7 is used for the above step S22.
In comparison with the initial position data read from the EEPROM in step S3, if they do not match, the process returns to step S25,
Open step excitation is performed to open the diaphragm. If the updated excitation state data and the initial position data match in step S28, the process proceeds to step S29.
In step S29, the output of PI7 is confirmed,
If the output is on at the Lo level, it is not in the initial position, so the process returns to step S25, the open step excitation is performed, and the aperture open drive is continued. If the output of the PI7 is not turned on at the Hi level in the step S29, the open position is in the excited state, and the open detection switch PI7 detects the open position. Is determined to be in the opening position, the opening drive is ended, the process proceeds to step S30, and the opening sequence ends.

FIG. 9 is an adjustment flow chart showing a method of adjusting the state of the opening initial position of the aperture with the aperture adjuster. In step S41, the adjustment sequence of the opening initial position starts, and the process proceeds to step S42. Step S4
2. According to the above-mentioned narrowing-down flow chart in 2,
Drives the aperture stop. Here, the initial position data for exciting to the initial excitation state is still the above-mentioned EEPROM.
Since it is not written in, 1 out of 4 excitation states
Select one of the two excitation states. Also, the number of aperture steps is arbitrarily set to about 10 steps. When the aperture is narrowed down, the process proceeds to step S43.

From step S43, the aperture is opened and driven. In step S43, the final excitation state of the narrowing is set as the initial state, the initial excitation of the narrowing is performed, and the process proceeds to step 44. In step S44, an interval time T3 until the aperture moves to the next one step opening is set, and the process proceeds to step 45. In step S45, the set time t = T
Repeat step S45 until the time reaches 3, and set time T
After 3 has passed, the process proceeds to step S46. Step S4
At 6, move the next one-step excitation state to the open side,
It proceeds to step S47. In step S47, PI
7 is checked on / off. That is, if the PI7, which is an opening detection switch, transmits light and the output is on, it is determined that the aperture has not reached the initial opening position, the process returns to step S44, and the aperture is opened one step again. To drive. In step 47, the PI 7 is shielded by the detection piece provided on the arrow wheel 4, and if the output is not on, the process proceeds to step S48.

In step S48, the interval time T4 until the next step is moved to the open side is set, and the process proceeds to step S49. In step S49, step S49 is repeated until t = T4, and when the set time T4 has elapsed, the process proceeds to step S50. In step S50, the one-step excitation state is further shifted to the open side, and the aperture is driven to open. This position is the opening initial position, and this position is the first step after the opening detection switch PI7 is turned off. Then, the process proceeds to step S51.

In step S51, the above step S50 is performed.
The initial open position data of the excitation state of
Store in 5. At this point, the opening drive for adjusting the initial position ends. Then, the process proceeds to step S52, and from here, offset adjustment of the amount of narrowing is performed. In step S52, a narrowing design value is set as the number of narrowing steps in order to narrow down to a predetermined aperture diameter, and the flow proceeds to step S53. In step S53, narrowing-down drive is performed according to the above-described narrowing-down flowchart (see FIG. 6). However, step S2 of the same flowchart
The reading of the EEPROM and the calculation of the aperture step number in step S3 are replaced by the aperture step number setting in step 52. Then, the process proceeds to step S54.

In step S54, the difference between the number of narrowing steps obtained by actually measuring the narrowed aperture and the number of narrowing design values set in step S52 is calculated as a narrowing offset adjustment value. This narrowing offset adjustment value is set to the EEPROM.
Store in 15. This narrowing-offset adjustment value is included in the aperture step number calculation in step S3 of the above-described narrowing-down subroutine. For example, assuming that one step of the stepping motor is designed to correspond to a quarter aperture value with an aperture, the actual aperture value (AV value) when targeting F8 (aperture value 6) is 5.625. <AV <5.875 +1 (step) 5.875 <AV <6.125 0 (step) 6.125 <AV <6.375 -1 (step) In addition to the design value for narrowing down, the error in narrowing down can be suppressed to 1/2 or less of the minimum resolution (1/4 AV value).

By performing the above-mentioned adjustment, it becomes unnecessary to adjust the complicated mechanism at the time of assembling the stepping motor, and the accurate adjustment can be easily performed by the software of μCOM. Conventionally, when assembling the stepping motor to the diaphragm unit, the motor is excited to a specific state,
Moreover, since a leaf switch etc. was used to detect the open position, it was necessary to finely adjust the rotational position.
By storing the excited state of the initial position and the offset adjustment value in the EEPROM as in this embodiment, the stepping motor can be assembled at random.

[0031]

According to the present invention, the aperture opening diameter is limited by the fixed aperture (mask) of the aperture cam plate, and the position of the aperture blade is detected at a position opened by two steps or more from the aperture of the fixed aperture. With the position opened one step further as the initial position, the stepping motor is de-energized and the diaphragm blades are maintained by the self-holding force of the stepping motor itself, so even if vibration or strong external force is applied to the camera, Since there is a margin of 3 steps or more to the aperture open aperture, the camera battery is not wasted.
In addition, the open state of the diaphragm can be maintained without requiring a special lock mechanism. Further, since the excitation state at the initial position is written in the EEPROM, even if the stepping motor moves when the aperture is opened, the aperture is always narrowed down from the initial position and the exposure accuracy is not deteriorated.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a diaphragm mechanism of a diaphragm control device showing an embodiment of the present invention.

FIG. 2 is an enlarged front view of a main part of the diaphragm mechanism of the above embodiment.

FIG. 3 is an enlarged front view of an essential part of the diaphragm mechanism of the above embodiment.

FIG. 4 is a diagram showing the timing relationship between the operating position of the diaphragm blades and the number of steps of the stepping motor in the diaphragm mechanism of the above embodiment.

FIG. 5 is a block diagram showing the overall configuration of the aperture control device of the above embodiment.

FIG. 6 is a flowchart showing an aperture narrowing operation of the aperture mechanism in the aperture controller of the above embodiment.

FIG. 7 is a diagram showing the relationship between the excitation state of the stepping motor and the PI output in the aperture control device of the above embodiment.

FIG. 8 is a flowchart showing the opening operation of the aperture mechanism in the aperture control device of the above embodiment.

FIG. 9 is a flowchart showing an adjusting operation of the diaphragm mechanism in the diaphragm control device of the above embodiment.

[Explanation of symbols]

 1 ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ ‥ 7 ... PI (Detection means)

Claims (1)

[Claims] 1. A stepping motor, a plurality of diaphragm blades, a diaphragm driving member which transmits a driving force from the stepping motor and causes the diaphragm blade to open and close, and a fixed aperture which determines a diaphragm opening diameter. Detecting means for detecting that the aperture diameter of the aperture blade is at a predetermined position that is larger than the aperture aperture diameter of the aperture; and for performing the opening operation of the aperture blade by driving the stepping motor, A diaphragm control device comprising: a control unit that stops the operation of the stepping motor after detecting that the predetermined position has been reached.