JPS6321631A - Diaphragm driving device - Google Patents

Abstract

PURPOSE:To operate a diaphram blade speedily and accurately by driving a stop through the relative rotation between two rings, moving the diaphragm in one direction in the reciprocal operation, and locking the rings alternately. CONSTITUTION:A voltage is applied to a lamination type piezoelectric element 13 and then a lever 8 rotates clockwise to energize both internal and internal rings 3 and 2 which are pressed against a roller 9 clockwise. Only the external ring 2 rotates clockwise owing to the difference in locking force between sliding members A and B and the quantity of rotation is about twice as large as the displacement of the roller 9, so respective blades 5 rotate clockwise around a pin 4 to start stopping-down operation. When the voltage application to the element 13 is stopped, the element 13 moves reversely to its original position and the lever 8 rotates counterclockwise. At such a time, the locking forces of the member A to the external ring 2 is stronger than that of the member B to the internal ring 3, so the external ring 2 does not rotate and the internal ring 3 rotates according to the counterclockwise rotation of the roller 9. Therefore, the diaphragm blades 5 rotate clockwise through the relative rotation between both internal external rings to perform stopping-down operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an aperture driving device for a photographing lens in a camera or the like.

(Prior Art) In a photographic lens, particularly an SLR photographic lens, the aperture blades built into the photographic lens section are generally driven from the main body side by a mechanical transmission mechanism such as a lever. However, recently, aperture devices have become lighter, thinner, and smaller.
In order to achieve this, a device has been proposed in which the aperture blades are driven by electromagnetic means. Furthermore, a device has been proposed in which a bimorph type piezoelectric element is used as a drive source and the aperture blades are driven by displacement when a voltage is applied.

[Problem that the invention seeks to solve]

The drive device using electromagnetic means requires a magnetic core and a coil to constitute the magnet, but since the storage volume is naturally limited, only extremely small magnets can be used. Therefore, the driving torque is small and acceleration is slow. Moreover, since there is inertia, there is also a drawback that positioning with a high degree of precision is difficult. In addition, since it is subject to the magnetic influence of the magnet, it is difficult to use materials such as iron for the aperture blades and other constituent members, resulting in strength problems. For this reason, it is currently only used as a program shutter for the lens shutter of LS.

On the other hand, a device using a bimorph type piezoelectric element as a drive source inherently has a small displacement and is not suitable for driving an aperture shank structure. For this reason, it has not yet been put into practical use.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an aperture drive device that has a large drive torque, is capable of high-speed and accurate operation, is free from magnetic influence, and has no problems with strength.

[Means for solving problems]

In order to solve the above problems and achieve the objectives, the present invention has the following features:
It is characterized by the following measures:

■ Provide two rings that are coaxially rotatable.

(2) A plurality of aperture blades are provided whose two ends engage with these two rings and whose aperture diameter is determined by the relative rotation angle of the two rings.

(2) A rotating member is provided that brings its circumferential surface into contact with the two rings and applies rotational force to the two rings.

(2) A driving means is provided for reciprocating this rotating member around the rotation centers of the two rings.

(2) A locking means is provided for alternately locking the two rings when the rotating member moves forward and backward.

[Effect]

By taking such measures, the following effects are achieved. In other words, the diaphragm is driven by the relative rotation of the two rings, and the two rings are alternately locked so that the diaphragm is moved in one direction during both reciprocating movements by the driving means, so that the piezoelectric element Even with a drive means with a small drive displacement like this, the aperture blades can be operated quickly and with a good 11 degrees. Furthermore, since no magnets are used, there is no magnetic influence and no strength problems arise.

〔Example〕

1 and 2 are a front view and a sectional view showing the structure of an embodiment of the present invention. As shown in FIGS. 1 and 2, the base plate 1 of the diaphragm device includes two diaphragm rings 2.3.
is rotatably mounted concentrically with the substrate 1. The outer ring 2 has a plurality of concentric rings arranged at equal intervals (six in this example).
A bin 4 is provided. Similarly, a plurality of (six in this example) grooves 38 are formed in the inner ring 3. Aperture blades 5 are attached corresponding to these bins 4 and grooves 3a. That is, the diaphragm blade 5 has a hole provided in a part thereof engaged with the bottle 4, and a hole provided in a part thereof engages with the bottle 4, and a hole provided in the other part thereof has the same size as the bottle 6.
is engaged with the groove 38.

A mounting plate 7 is arranged so as to press down these aperture blades 5.

The two aperture rings 2 and °3 have two rising parts 2a and 2b, respectively, in which the aperture blades 5 are attached in opposite directions.
, 3b and 3C are provided at three locations. A lever 8 rotatably supported by a shaft 8a is arranged on the other surface of the substrate 1, that is, the surface opposite to the side on which the aperture rings 2 and 3 are attached. A roller 9 as a rotating member made of hard rubber or the like is rotatably supported at one end of the lever 8, that is, one end located on the opposite side of the shaft 8a with respect to the center of the substrate 1. This O-La 9 is
Eleven parts are attached between the above-mentioned rising parts 2a and 3b so that the peripheral surface is pressed against the rising parts 2a and 3b. A bottle 10 is arranged at the other end of the lever 8,
A spring 12 is attached between the bottle 11 and the bottle 11 arranged on the substrate 1.

This lever 8 is thus biased counterclockwise.

Further, near one end of the lever 8, a laminated piezoelectric element 13 is disposed as a driving means, with one end in contact with the lever 8 and the other end fixed to the substrate 1.

On the other hand, the other rising portion 2b of the aperture ring 2 is provided with an elastic plate 21. Piezoelectric element 22. ! A sliding member A, in which the fivJ absorbing plate 23 and the fixing member 24 are integrated, is biased by a leaf spring 25 and placed in a crimped manner.

Further, on the other rising portion 3C of the aperture ring 3, an elastic plate 31. Piezoelectric element 32. Vibration absorbing plate 33. Fixed member 34
A sliding member B, which is integrated with the above, is biased by a leaf spring 35 and placed in a crimped manner.

As shown in FIG. 3, the piezoelectric elements 22 and 32 are composed of a plurality of piezoelectric bodies (34 in this example) having mutually different polarization directions. Each is bimorph bent.

Next, the operation will be explained with reference to FIGS. 5 and 6. A pulsed voltage as shown in FIG. 5 is applied to the laminated piezoelectric element 13 and the pressure-N elements 22, 32 in the two sliding members A and B. That is, a voltage is applied to the piezoelectric element 22 of the opening member A at the same time that a voltage is applied to the laminated piezoelectric element 13, and a voltage is applied to the piezoelectric element 32 of the sliding member B.
A voltage is applied to the stacked piezoelectric element 13 when no voltage is applied to it.

Now, when a voltage is applied to the laminated piezoelectric element 13, the piezoelectric element 13 is elongated and displaced in the direction of the arrow in FIG. 6, causing the lever 8 to rotate clockwise. At this time, the pressure N element 22
Since a voltage is applied to the sliding member A, the elastic plate 21 of the sliding member A is bent and comes into contact with the rising portion 2b of the outer ring 2, but this contact portion is only at the peak of the bent portion. On the other hand, the elastic plate 31 of the sliding member B
It is in full pressure contact with. Therefore, due to the clockwise rotation of the lever 8, the inner ring 3. is in pressure contact with the row 59. Both outer ring 2 is biased clockwise, but sliding member A,
The locking force of B is much larger for inner ring 3, so
The inner ring 3 does not rotate, and as a result, only the outer ring 2 rotates clockwise as the row 59 rotates clockwise. The amount of rotation of the outer ring 2 at this time is approximately twice the displacement of the roller 9 by the lever 8. Therefore, each aperture blade 5 rotates clockwise around the bin 4 to start narrowing down.

Next, when the voltage application to the laminated piezoelectric element 13 is stopped, the laminated piezoelectric element 13 is displaced in the opposite direction to its original position. Then, the lever 8 rotates counterclockwise due to the tensile force of the spring 12 attached to the other end of the lever 8. At this time, since a voltage is applied to the piezoelectric element 32 of the sliding member B, the elastic plate 31 is bent and comes into contact with the rising portion 3C, but this contact portion is only at the peak of the bent portion. On the other hand, the elastic plate 21 of the sliding member A is in full pressure contact with the rising portion 2C of the outer ring 2. Therefore, in this case, the sliding member A has a stronger locking force on the outer ring 2 and the inner ring 3. Therefore, the outer ring 2 does not rotate, and the inner ring 3 rotates counterclockwise as the roller 9 rotates counterclockwise. As a result, the aperture blades 5 further rotate clockwise due to the relative rotation between the outer ring 2 and the inner ring 3 and are narrowed down.

By repeating this operation a predetermined number of times, a predetermined aperture thread can be obtained. In order to operate the aperture blades 5 in the opposite direction, the timing of voltage application to each piezoelectric element 22, 32 of sliding members A and B with respect to the voltage application to the laminated piezoelectric element 13 is set in a relationship opposite to that in the above case. Just do it.

Note that the present invention is not limited to the above embodiments.
For example, in the embodiment described above, the friction roller 9 was used with the aperture ring 2.3 as the driving unit, but a gear or the like may also be used. Further, although a spring is used to return the lever 8, a plurality of piezoelectric elements that operate alternately may be used. Further, although the sliding members A and B are used as means for locking the aperture ring 2.3, the present invention is not limited to this. Furthermore, in order to further improve the aperture amount control, an encoder function may be added to the aperture ring 2.3, and the relative or absolute position of each ring may be determined and fed back to the drive of the piezoelectric element group. Furthermore, the laminated piezoelectric element 13 is driven at several kth,
The lever ratio may be increased by utilizing the high stress generated by the piezoelectric element 13, and the displacement of the roller 9 may be further increased. In this way, the aperture blades 5 can be operated from the aperture opening to the minimum aperture within several milliseconds, and therefore can be used not only for driving the aperture blades 5 but also as a lens shutter driving device. Of course, various other modifications can be made without departing from the spirit of the present invention.

〔Effect of the invention〕

According to the present invention, the diaphragm is driven by the relative rotation of the two rings, and the rings are alternately locked so that the diaphragm is moved in one direction during both reciprocating movements of the driving means. Therefore, the aperture blades can be operated quickly and accurately even with a drive means such as a piezoelectric element that has a small drive displacement.

Also, since no magnets are used, there is no magnetic influence.

In this way, it is possible to provide an aperture drive device that has a large drive torque, can operate at high speed and with high precision, is free from magnetic influence, and has no problems with strength.

[Brief explanation of the drawing]

1 and 2 are front views and sectional views showing one embodiment of the present invention, FIGS. 3 and 4 are perspective views showing the configuration and operating mode of the piezoelectric element of the same embodiment, and FIG. The diagrams illustrating the waveforms of the applied voltage for driving, and FIGS. 6 and 7 are operation explanatory diagrams. DESCRIPTION OF SYMBOLS 1... Substrate, 2.3... Two rings, 5... Aperture blade, 9... Roller (rotating member), 12... Return spring, 13... Laminated piezoelectric element, A , B...Sliding member (locking means). Applicant's agent Patent attorney Atsushi Gaiben Figure 2 N, 32 Figure 3 Figure 4 Figure 5 Figure 6 Figure M7 Procedure ``■ Masaaki in 1939! 9/5th Commissioner of the Patent Office Black 1) Akira M], Indication of the case, Patent Application No. 166121/1986 2, Name of the invention Aperture drive device 3, Person making the amendment Relationship to the case Patent applicant (037) Olympus Optical Industry Co., Ltd. 4, Agent Tokyo USE Hill 5, 3-7-2 Kasumigaseki, Chiyoda-ku, Voluntary amendment 6, Full text of specification subject to amendment 7, Contents of amendment

Claims (1)

[Claims] two rings arranged coaxially and rotatably, a plurality of aperture blades whose two ends engage with these two rings and whose aperture diameter is determined by the relative rotation angle of the two rings; a rotating member that brings its peripheral surface into contact with the two rings and applies rotational force to the two rings; a drive means that reciprocates the rotating member around the rotation centers of the two rings; 1. A diaphragm drive device comprising a locking means for alternately locking the two rings during movement.