JP5134697B2 - Aperture device - Google Patents

Description

  The present invention relates to an aperture device for an optical apparatus such as a compact digital camera or a single-lens reflex camera. In particular, the present invention relates to an aperture device that can smoothly open and close following changes in the brightness of a subject during moving image shooting.

  A conventional diaphragm device is of a type that opens and closes an optical path opening by driving a plurality of diaphragm blades with an annular windmill that rotates about an optical axis. Pins are planted on each diaphragm blade or ground plate, cam grooves are formed on the ground plate or each diaphragm blade, and each pin engages with the edge of each cam groove by rotating each diaphragm blade with a windmill. When pressed, each diaphragm blade rotates about the rotation fulcrum to open and close the optical path opening.

  In a diaphragm device having a pin that slides in the cam groove in this way, if there is a clearance between the pin and the cam groove, the movement of the diaphragm blades is loose (also referred to as a step), making it difficult to smoothly adjust the amount of light. It becomes. In particular, in moving image shooting, when a play occurs when the optical path opening is closed, an abrupt change in the amount of light appears prominently in the change in brightness of the captured image, resulting in a moving image that gives a sense of incongruity. Although it is possible to mechanically eliminate the clearance between the pin and the cam groove, the clearance is designed to have a slight clearance in order to cope with changes in temperature and humidity.

  As a countermeasure for smoothly driving the diaphragm blades while including such play, a diaphragm device that urges the blade body of the diaphragm blades with a leaf spring and urges the slide pin to the edge of the cam groove has been proposed. (For example, refer to Patent Document 1). In the case of this device, the leaf spring needs to have a certain width. Then, the spring constant becomes high and the fluctuation of the urging force becomes large, which is not preferable. Further, when the blade body is made of resin, there is a problem that when the blade body is biased, the blade body is bent and deformed.

JP-A-6-265773

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a diaphragm device that can smoothly drive the diaphragm blades by eliminating backlash between the pin and the cam groove when the diaphragm blades are opened and closed. .

Underlying first aperture Ri apparatus of the present invention has the blade body to narrow the opening of the optical path, and has a slide pin, and a diaphragm blade to narrow the opening of the light path, a cam groove for guiding the slide pin A throttle plate comprising a cam plate, and further comprising a wire spring that biases the slide pin, wherein the wire spring has a free posture without biasing force at an open limit position of the diaphragm blade. Thus, a gap is opened between the spring and the slide pin.

According to the present invention, since the slide pin of the diaphragm blade is urged toward the edge of the cam groove by the wire spring to eliminate the play between the pin and the cam groove, the diaphragm blade can be smoothly opened and closed. . In other words, since the pressure is always applied from the wire spring to the aperture blades at positions close to the aperture, which is sensitive to the aperture other than the open limit position, the slide pin is unlikely to move suddenly and opens and closes smoothly. can do. In this way, there is no sudden change in aperture due to hysteresis in the opening / closing direction and changes in gravity / inertial force applied to the camera, and in particular, aperture performance during moving image / continuous shooting of a single-lens reflex camera is improved. It should be noted that the urging force (pressurization) applied to the diaphragm blades is zero at the diaphragm opening limit, and the diaphragm blades fluctuate. However, at the opening limit, a very high diaphragm performance is not required, so that no particular problem occurs. Alternatively, the open optical path opening may be determined by a fixed opening such as a base plate or a cover, without using the diaphragm blades.
It should be noted that the urging force on the diaphragm blades is zero at the diaphragm opening limit, but if the diaphragm blades are rotated, the slide pin comes into contact with the wire spring. Energize. The range where the urging force of the diaphragm blades is zero is preferably a range of about 10% or less near the open limit.

  In the aperture device of this aspect, when the aperture is fully open, the wire spring is in a free posture with no urging force. That is, in the open limit position, the pressure of the wire spring is zero, and there is a clearance between the spring and the pin. Therefore, at the time of assembly, after placing the diaphragm blades at a predetermined position at the open end of one ground plate, the wire spring may be placed on the other ground plate (the reverse order may be used). Alternatively, if you assemble a part that incorporates the spring in a free position (base plate, cam plate, cover, etc.) and a part that incorporates the aperture blade in the open limit position, the spring and aperture blade automatically open Assembled into. That is, the aperture blade can be incorporated without artificially deforming the wire spring. When the wire spring is thin, it is preferable to avoid touching the wire spring as much as possible at the time of assembly because permanent deformation of the wire spring and change in spring characteristics can be avoided. In addition, the number of steps in the assembly process is reduced.

  On the other hand, if the wire spring is in contact with the pin even in the open limit position, an operation for deforming the wire spring is required at the time of assembly, which is an operation using nerves, and there is a concern about damage of the spring as described above.

  Further, since the spring biases the slide pin of the diaphragm blade, there is no problem such as deformation of the blade body (light path shielding film portion) that occurs when the blade body of the diaphragm blade is biased. In addition, when urging the blade body, it was necessary to use a leaf spring having a certain width and a relatively high spring constant (a wire spring works well on the side of the film-like diaphragm blade body). Since the wire spring is used in the present invention, the spring constant can be lowered, and the urging force and its variation can be reduced.

  In addition, as the opening / closing drive mechanism of the diaphragm blades, there is a type in which the cam plate is rotated without using the windmill, in addition to the method of rotating the pins of the plurality of diaphragm blades via the windmill. The aperture blade opening / closing drive mechanism may be a manual aperture type that does not use an actuator such as a motor.

The underlying second aperture Ri apparatus of the present invention has the blade body to narrow the opening of the optical path, and has a slide pin, and a diaphragm blade to narrow the opening of the light path, a cam groove for guiding the slide pin And a cam plate, further comprising a wire spring that biases the slide pin, the wire spring abutting and sliding on a surface of the slide pin closer to the optical path center, The slide pin is urged outward in the optical path.

  According to the present invention, the wire spring abuts and slides on the surface of the slide pin on the optical path opening side, and urges the pin outward (in the direction opposite to the optical path opening center direction). In other words, the operating region of the wire spring is not near the outer periphery of the diaphragm device but near the optical path opening. That is, since the vicinity of the outer periphery of the diaphragm device is an area that does not interfere with the operation of the wire spring, the engaging portion between the diaphragm device and the lens barrel and the attachment portion for other parts can be arranged near the outer periphery of the diaphragm device.

  On the other hand, when the wire spring is arranged outside the diaphragm blade and the diaphragm blade is urged inward (in the direction of the optical path opening center), the wire spring exists near the outer periphery of the diaphragm device. Then, interference with the movement of the wire spring becomes a problem, and there is a restriction on the arrangement of the engaging portion between the diaphragm device and the lens barrel and the mounting portion of other components. That is, as in the present invention, the wire spring is brought into contact with and slides on the surface on the optical path opening side and is urged outwardly from the optical path opening. The degree of freedom of expansion / contraction of the outer diameter of the device will increase.

  In this aspect, when the aperture blade is at a position other than the vicinity of the open limit, the linear spring abuts and slides on a surface of the slide pin near the center of the optical path, and the slide pin moves in the optical path outward direction. It is preferable to energize.

  According to the present invention, in particular, since the wire spring contacts and slides on the surface of the slide pin on the optical path opening side, the wire spring is in a free posture at the limit when the pin comes to the outer position, and between the spring and the pin at the time of the limit. Easy to open the gap.

In the above aspect, the wire spring has a spoiled winding portion, a hook arm connected to one end of the spiral winding portion, and a slide pin abutting arm connected to the other end, and the spring is attached to the cam plate. supporting Ten及 beauty spring hooking portion is erected, the spiral lap winding portions of the wire spring is fitted into the spring supporting point of the cam plate, wherein the hook arm is engaged with the spring hook portion It is preferable.

According to the present invention, the spring supporting point of the cam plate, fitted to Suparairu lap winding portions of the wire spring can be set easily wire spring with only the cam plate to engage the arm hooked to the spring hook.

Cam third aperture Ri apparatus, which has the blade body to narrow the opening of the optical path, and the slide pin, and has a diaphragm blades narrow the opening of the light path, a cam groove for guiding the slide pin in connection with the present invention And a plate spring for biasing the slide pin, and the diameter of the wire spring is 0.2 mm or less.

  The lower the spring constant of the wire spring, the smaller the biasing force of the slide pin, so that the output of the aperture blade rotation actuator is small and stable.

  In the first aspect and the second aspect of the present invention, it is preferable that a diameter of the wire spring is 0.2 mm or less. The diameter of the wire spring is preferably 0.15 mm or less, more preferably 0.1 mm or less. The material of the spring is preferably a stainless steel wire, a hard copper wire, a drawn copper wire or the like, but other spring materials are also applicable.

  Moreover, it is preferable that the spring constant of the said wire spring is 0.01-2.20 gf * mm / deg. The spring constant of the wire spring is preferably 0.02 to 0.15 gf · mm / deg, more preferably 0.05 to 0.10 gf · mm / deg.

  Furthermore, it is preferable that the urging force of the wire spring is 0.10 to 25 gf · mm. The urging force of the wire spring is preferably 0.25 to 1.50 gf · mm, more preferably 0.40 to 1.30 gf · mm.

  Furthermore, it is preferable that the number of turns of the spoiled winding portion of the wire spring is 1 to 6 times. The number of windings is preferably 1 to 5 times, more preferably 1 to 3 times. As the number of turns of the spirally wound portion of the wire spring increases, the spring constant decreases while the thickness of the spring increases. It is preferable to reduce the spring constant by increasing the number of turns while suppressing an increase in thickness by using a thin wire spring.

An example of the basic concept of setting the wire spring wire diameter, spring constant, urging force, number of turns of the spiral winding portion, and setting of the specifications of the drive motor and the speed reducer will be described below.
Each specification of the wire spring must satisfy the following conditions.
(A) A wire spring having an urging force capable of countering the self-weight and inertia moment applied to the diaphragm blades is selected.
(B) The motor startability is not deteriorated beyond the practical range.
(C) Fit in the required space.
Based on these conditions, settings are made as follows.
(1) Since each part such as a motor and diaphragm blades is arranged in the required space, and a wire spring is arranged in the remaining restricted space, the shape of the wire spring is almost determined from now on. Further, the size and weight of the diaphragm blades are almost determined.
(2) As the basic shape of the wire spring designed based on (1) above, moment calculation and other specifications of the wire spring are determined. The position where the urging force of the wire spring becomes zero is, for example, 10% of the rotation stroke of the aperture blade from the closed limit to the open position, which is close to the open limit, by 25% (with the pin stroke). % Is preferred. In the closed position, it is preferable that the moment of gravity around the rotation fulcrum pin of the diaphragm blade / the moment of biasing force is in the range of 1/2 to 1/650. The moment ratio is more preferably 1/10 to 1/100, most preferably 1/20 to 1/50. The “gravity moment around the rotation fulcrum pin of the diaphragm blade” is “weight of one diaphragm blade × distance between the rotation fulcrum pin and the gravity center of the blade”. The “biasing force moment” is “wire spring urging force × distance between the rotation fulcrum pin and the slide pin.
(3) Calculate whether the motor and the speed reducer can output with the target of a torque equal to or more than three times the weight of the aperture blade + spring biasing force.
(4) If the target in the calculation of (2) or (3) is not reached, return to (1) or (2) and review.

  As is apparent from the above description, according to the present invention, the slide pin of the diaphragm blade is urged toward the edge of the cam groove by the wire spring to eliminate backlash between the pin and the cam groove. Smooth opening / closing operation of the blades becomes possible. Furthermore, if the urging force (pressurizing force) applied to the diaphragm blades is zero at the aperture opening limit, that is, if the wire spring has a free posture without urging force, the wire spring and the diaphragm blade can be incorporated independently, Undesirable permanent deformation and change in spring characteristics of the wire spring can be avoided. In addition, the number of man-hours for the assembly process can be reduced.

  Furthermore, if a thin wire spring having a relatively low spring constant is used, fluctuations in the biasing force can be reduced.

1A and 1B are diagrams illustrating a diaphragm device according to an embodiment of the present invention. FIG. 1A is a plan view when fully opened, and FIG. 1B is a plan view when fully closed (a cover is omitted). ). It is the figure which expanded a part of Drawing 1 (A) and Drawing 1 (B). It is a disassembled perspective view of the diaphragm | throttle device of FIG. It is a top view of the ground plane B of the aperture_diaphragm | restriction apparatus of FIG. FIG. 5A is a plan view of the wire spring, and FIG. 5B is a plan view showing a state in which the wire spring is housed in the base plate B. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, with reference to FIG. 3, the structure of the diaphragm | throttle device concerning embodiment of this invention is demonstrated. FIG. 3 is an exploded perspective view of the diaphragm device of the present invention.
The diaphragm device 1 includes a plurality of diaphragm blades 10 (seven in this example, only one is shown in FIG. 1) for narrowing the optical path opening, and a windmill 20 that rotates the diaphragm blades 10 around the optical axis OA. And a base plate A30 and a base plate B (cam plate) 40 in which an optical path opening is formed, a wire spring 50 that urges each diaphragm blade 10, and a cover 60 that holds the wire spring 50.

First, each component will be described.
All the diaphragm blades 10 have the same shape, and include a blade body 11 and a slide pin 12 implanted in the blade body 11. The blade body 11 is made of, for example, a resin film (in one example, a polyester film) that has been coated with a light shielding ability. The blade body 11 is substantially semicircular, and an arcuate diaphragm forming edge 11a is formed on the inner periphery. An optical path centered on the optical axis OA is formed by the diaphragm forming edge 11 a of each blade member 10. The slide pin 12 is implanted at the end of one surface of each blade body 11. A rotation fulcrum pin 15 of the diaphragm blade 10 is implanted on the opposite surface of each blade body 11.

The windmill 20 is a ring-shaped thin member. The wind turbine 20 has the same number (7 in this example) of holes 21 as the number of aperture blades 10 formed at equal intervals. The rotation fulcrum pins 15 of the diaphragm blades 10 are fitted into the holes 21 so that the diaphragm blades 10 can rotate around the holes 21.
Further, a protrusion 23 is formed on a part of the outer periphery of the windmill 20 so as to project outward. This protrusion 23 is for positioning the windmill 20. Further, a rack 25 is formed on a part of the outer periphery. As will be described later, the rack 25 meshes with a pinion 36 fixed to the rotating shaft of a motor 35 attached to the main plate A30. The windmill 20 rotates about the optical axis OA by the rotation of the motor 35.

The base plate A30 and the base plate B40 have substantially the same hollow disc shape, and optical path openings 31 and 41 are formed in the center. The aperture blade 10 and the windmill 20 are supported between the main plate A30 and the main plate B.
Around the optical path opening 31 on one surface of the base plate A30 is a concave portion 33 on which the diaphragm blades 10 and the windmill 20 are placed. A motor 35 is attached to the opposite surface of the main plate A30. The rotation shaft of the motor 35 protrudes into the recess 33 through the ground plane A30. A pinion 36 that meshes with the rack 25 of the wind turbine 20 is fixed to the protruding rotating shaft.

The base plate B40 (cam plate) will be described with reference to FIG.
A periphery of the optical path opening 41 on one surface of the ground plane B40 (a surface opposite to the ground plane A30) is a concave portion 43 in which a later-described wire spring 50 is accommodated. The recess 43 is formed with the same number of cam grooves 45 as the number of diaphragm blades 10 (seven in this example). The cam groove 45 has the same shape and is formed obliquely from the outside to the inside of the main plate B40. The slide pin 12 of the diaphragm blade 10 is engaged with the cam groove 45. A spring fulcrum boss 47 as a spring fulcrum is provided upright on the side of each recess 43 in each cam groove 45. Further, a spring hooking boss 48 as a spring hooking portion is erected on the side of each spring fulcrum boss 47 in the direction opposite to the cam groove 45.

  On the outer side of each of the recesses 33 and 43 of the base plate A30 and the base plate B40, there are protrusions, recesses, and holes that are engaging portions with the lens barrel and other parts (control electronic components PI and the like). A notch or the like is formed.

The wire spring 50 will be described with reference to FIG. 5A is a plan view of the wire spring, and FIG. 5B is a diagram showing a state in which the wire spring is set on the ground plane B. FIG.
The wire spring 50 is a torsion spring, and as shown in FIG. 5A, a spoiled winding portion 51, a hook arm 52 connected to one end of the spiral winding portion 51, and a slide connected to the other end. And a pin abutting arm 53. The tip 52a of the hook arm 52 is folded back into a U shape. In this example, the angle between the arms 52 and 53 in the free posture is 115.87 ° (design value).

The material of the wire spring 50 is preferably a stainless steel wire, a hard copper wire, a drawn copper wire or the like, and preferably has a lower spring constant. This is because the lower the spring constant, the smaller the fluctuation of the urging force of the pin 12 of the diaphragm blade 10. The spring constant is 0.01 to 2.20 gf · mm / deg, preferably 0.02 to 0.15 gf · mm / deg, more preferably 0.04 to 0.10 gf · mm / deg. It is selected to satisfy either condition.
(1) The diameter of the wire spring is 0.2 mm or less, preferably 0.15 mm or less, more preferably 0.1 mm or less. A thinner wire diameter is preferable because the spring thickness can be reduced.
(2) The urging force moment of the wire spring is 0.10 to 25 gf · mm, preferably 0.25 to 1.50 gf · mm, more preferably 0.40 to 1.30 gf · mm.
(3) The number of turns of the spoiled winding portion of the wire spring is 1 to 6 times, preferably 1 to 5 times, more preferably 1 to 3 times. In addition, it is preferable that the height of the winding portion is as low as possible because the diaphragm device can be thinned.
However, the spring constant varies depending on the diameter of the optical path opening of the diaphragm device, the shape / weight / number of diaphragm blades, the outer diameter of the diaphragm device, etc., but is selected to be as low as possible. The arm length of the spring varies depending on the number of blades.
An example of setting each item will be described later.

  As shown in FIG. 5B, in the wire spring 50, the spiral winding portion 51 is fitted into the spring fulcrum boss 47 erected in the concave portion 43 of the main plate B40, and the folded portion 52a at the tip of the hook arm 52 is provided. A spring hook boss 48 is hooked and attached. When actually assembling, for example, the linear part of the slide pin abutment arm 53 or the hook arm 52 of the wire spring 50 is pinched with tweezers or the like, the winding portion 51 is aligned with the spring fulcrum boss 47, and the folded portion The wire spring 50 may be dropped by aligning 52a with the spring hook boss 48. If one point of the linear arms 52 and 53 is pinched, no bending force is applied to the wire spring 50, so that the wire spring 50 can be attached to the main plate B40 in a natural posture. At this time, if the clearance between the spring fulcrum boss 47 and the spiral winding portion 51 of the wire spring 50 is set to about 0.1 mm, the winding portion 51 can be fitted into the spring fulcrum boss 47 simply by dropping the wire spring 50. it can. In this posture, the slide pin contact arm 53 extends across the cam groove 45 (passing between the outer end and the inner end of the cam groove 45) and beyond the inner end of the cam groove 45.

  The cover 60 is a thin ring-shaped member that closes the recess 43 of the ground plane B 40 and holds the wire spring 50 in the recess 43. In the cover 60, a groove having the same shape as the groove is formed at the same position as the cam groove 45 of the base plate B40. Further, a hole through which each spring fulcrum boss 47 and the spring hook boss 48 are erected on the base plate B40 is formed.

With reference to FIG. 1 and FIG. 2, the optical path opening opening / closing operation | movement of this aperture_diaphragm | restriction apparatus 1 is demonstrated. Each figure (A) shows when fully open, and each figure (B) shows when fully closed. In each figure, the cover 60 is omitted.
When the apertures are fully opened as shown in FIGS. 1A and 2A, the aperture forming edges 11a of all aperture blades 10 are positioned slightly outside the optical path openings 31, 41 of the ground plane A30 and the ground plane B40, and the optical path The openings 31 and 41 are fully open. 2A, the slide pin 12 of each diaphragm blade 10 is located at the outer end of the cam groove 45 of the main plate B40. At this time, the slide pin abutting arm 53 of the wire spring 50 is located inside the slide pin 12 (on the optical path opening side), and the arm 53 and the slide pin 12 are not in contact with each other and the gap C is open. That is, the wire spring 50 is in a natural posture with no load applied, and no pressure is applied to the slide pin 12.

  A pinion 36 fixed to the output shaft of the motor 35 is engaged with the rack 25 of the windmill 20. When the motor 35 is driven and the pinion 36 rotates, the windmill 20 starts to rotate in the clockwise direction in FIG. 1 about the optical axis OA via the rack 25.

  Along with the rotation of the windmill 20, the aperture blade 10 that is rotatably supported by the windmill 20 also moves in the same direction as the windmill 20. The slide pin 12 of the diaphragm blade 10 also moves in the same direction as the windmill 20 as indicated by the arrow in FIG. 2A, but is pushed by the outer edge of the cam groove 45, so that the slide pin 12 It advances along the groove 45 from the outer end. Then, the aperture blade 10 starts to turn counterclockwise around the fulcrum pin 15 in the figure. When the diaphragm blade 10 further rotates, the slide pin 12 continues to be pushed by the outer edge of the cam groove 45, and the diaphragm blade 10 continues to turn counterclockwise in the drawing. Thereby, as shown to FIG. 1 (B) and FIG. 2 (B), each aperture blade 10 penetrate | invades so that the optical path openings 31 and 41 of the ground plane A30 and the ground plane B40 may be block | closed.

Next, the action of the wire spring 50 accompanying the optical path opening / closing operation will be described with reference to FIG.
As shown in FIG. 2A, when fully opened, the slide pin 12 of each diaphragm blade 10 is located at the outer end of the cam groove 45 of the main plate B40. The slide pin 12 is located outside the slide pin contact arm 53 of the wire spring 50 (on the side opposite to the optical path opening) and is not in contact with the arm 53. That is, no pressure is applied to the slide pin 12 from the wire spring 50. Since the slide pin 12 and the cam groove 45 are designed to have some clearance between them, the diaphragm blades 10 are slightly fluctuated in a natural state, but a high degree of diaphragm performance is not required when fully opened, which is particularly problematic. Does not happen

  When the windmill 20 rotates and the aperture blade 10 rotates in the clockwise direction in the drawing when the optical path opening is closed, the slide pin 12 advances along the cam groove 45 as described above. Then, since the slide pin contact arm 53 of the wire spring 50 exists in the moving direction of the slide pin 12, the slide pin 12 eventually contacts the outside of the slide pin contact arm 53. When the slide pin 12 further advances in the cam groove 45, the slide pin 12 automatically pushes the slide pin abutting arm 53 of the wire spring 50 inward (on the optical path opening side). In other words, the slide pin 12 is pressed against the outer edge of the cam groove 45 by applying a pressure from the slide pin abutting arm 53 in the outward direction (the side opposite to the optical path opening). Thus, the slide pin 12 advances in the cam groove 45 in a state where the slide pin abuts the arm 53 and is pressed against the outer edge of the cam groove 45, that is, in a state where there is no clearance (backlash) from the cam groove 45. Since the slide pin abutting arm 53 extends beyond the inner end of the cam groove 45, the slide pin 12 moves to the arm 53 until the slide pin 12 reaches the inner end of the cam groove 45 (until the optical path opening is fully closed). Receive the reaction force.

  In addition, when opening an optical path, the motor 35 is reversely rotated and the windmill 20 is rotated in the opposite direction. Also in this case, since the slide pin 12 of the aperture blade 10 continues to receive the reaction force in the outward direction from the slide pin abutting arm 53 of the wire spring 50, the slide pin 12 is free from play with the cam groove 45. Then, the cam groove 45 advances outward.

  In this way, when the aperture is opened and closed, the slide pin 12 is urged toward the edge of the cam groove 45 by the wire spring 50 to eliminate the play between the pin 12 and the cam groove 45, so that the aperture blade 10 can be opened and closed smoothly. Operation is possible. In particular, when the aperture of the optical path is narrowed, the pressure is always applied from the wire spring 50 to the diaphragm blade 10, so that the slide pin 12 (the diaphragm blade 10) is unlikely to move rapidly. In particular, since the spring constant of the wire spring 50 is small, fluctuations in the urging force can be reduced. As a result, there is no change in aperture due to hysteresis in the opening / closing direction and changes in gravity and inertial force applied to the camera, and the aperture performance of a single-lens reflex camera during moving image / continuous shooting is improved.

  Further, in the diaphragm device of a single-lens reflex camera, it is expected that the tendency for the outer diameter of the diaphragm device to be small and the optical path aperture diameter to be increased further in the future. In this case, a configuration in which a resin slide pin (or a stainless steel slide pin when the blade body is made of metal) is implanted in a resin diaphragm blade is the mainstream. In the present invention, even if the diaphragm blade is made of resin, a pressure is applied to the slide pin 12 of the diaphragm blade 10, so that the blade body 11 is not deformed.

Further, the diaphragm device of the present invention has the following advantages.
(1) When fully opened, the urging force (pressure) applied to the aperture blade 10 is zero and the wire spring 50 is in a free posture, so that the aperture blade 10 and the wire spring 50 can be incorporated independently. Specifically, the diaphragm blade 10 may be placed so as to be fully opened with respect to the windmill 20 installed in the recess 33 of the ground plane A30, and then the wire spring 50 may be placed at a predetermined position on the ground plane B40. Or the reverse order may be sufficient. Since the wire spring 50 is thin and easily deformed, it is preferable to avoid touching it as much as possible at the time of assembly. However, in the present invention, the aperture blade 10 can be incorporated without artificially deforming the wire spring 50. For this reason, an undesirable permanent deformation of the wire spring 50 and a change in spring characteristics can be avoided. In addition, the number of steps in the assembly process is reduced.

(2) The slide pin contact arm 53 of the wire spring 50 contacts and slides on the surface of the slide pin 12 on the optical path opening side. That is, the wire spring 50 exists relatively on the optical path opening side of the ground plane B40. For this reason, the operation region of the wire spring 50 is a portion closer to the center (the optical path opening side) of the base plate B40, and the outer peripheral portions of the base plates A and B30, 40 do not interfere with the operation region of the wire spring 50. Accordingly, an engaging portion with a lens barrel or the like and an attachment portion for other components can be arranged on the outer peripheral portion. This increases the degree of freedom in setting the space between the lens barrel and the diaphragm (enlargement of the aperture diameter, expansion / contraction of the outer diameter of the diaphragm, etc.).

  In the present invention, as a mechanism for opening and closing the aperture blade, a slide pin is implanted in the aperture blade, a cam groove is formed in the base plate B, and the aperture blade is rotated by a windmill. It is possible to use various mechanisms if it is assumed to be planted. For example, it is good also as providing a cam groove in a windmill and rotating an aperture blade. The aperture blade opening / closing drive mechanism of the present invention can be a manual aperture type that does not use an actuator such as a motor.

  In the present invention, the number of aperture blades is seven, but other numbers are possible. A larger number of blades is preferable because the length of the slide pin abutting arm of the wire spring can be shortened, so that the processing accuracy of the wire spring is improved and deformation at the time of incorporation and handling is small.

An example of each specification of the diaphragm | throttle device of this invention is demonstrated.
(1) Diaphragm opening diameter: φ16.0 mm
Diaphragm outer diameter f38.0 mm.
(2) Wire spring wire diameter: 0.1 mm,
Material: Stainless steel,
Spring constant: 0.041 gf · mm / deg,
Energizing moment: 0.46 gf · mm (when fully closed)
Number of turns of spiral wound portion: 5.18 times.
(3) Diaphragm blade weight: 0.005 g,
Distance between slide pin and pivot pin: 4.18mm
The distance between the pivot point and the optical path opening center is 11.29 mm.

(4) Others Gravity moment around the rotation fulcrum pin of the diaphragm blade / Burning force moment applied to the slide pin of the wire spring at the closed position: 0.02 / 0.46 = 1/23. This moment ratio is preferably in the range of 1/2 to 1/650.
Clearance between wire spring and aperture blade at open limit: 0.1 mm. This clearance is preferably 0.05 to 1 mm.
Position where the urging force of the wire spring becomes zero: The position of about 10% of the rotation stroke of the diaphragm blades from the closed limit to the eye opening, which is close to the open limit. This value is preferably 5% to 25%.

DESCRIPTION OF SYMBOLS 1 Diaphragm | restriction apparatus 10 Diaphragm blade 11 Blade body 12 Slide pin 15 Rotation fulcrum pin 20 Windmill 21 Hole 23 Protrusion 25 Rack 30 Ground plate A 31 Opening 33 Recess 35 Motor 36 Pinion 40 Ground plate B (Cam plate) 41 Opening 43 Recess 45 Cam Groove 47 Spring fulcrum boss 48 Spring hook boss 50 Wire spring 51 Spiral winding part 52 Hook arm 53 Slide pin contact arm 60 Cover

Claims (3)

A blade body that narrows the opening of the optical path, and a slide pin, and a diaphragm blade that narrows the opening of the optical path;
A cam plate having a cam groove for guiding the slide pin;
An aperture device comprising:
Furthermore, it comprises a wire spring that urges the slide pin toward the edge of the cam groove to eliminate backlash between the slide pin and the cam groove,
At the open limit position of the aperture blade during the stepless optical path aperture stop operation for light quantity adjustment, the linear spring is in a free posture without biasing force, and a gap opens between the spring and the slide pin. With
When the diaphragm blade is in a position other than the vicinity of the open limit during the stepless optical path aperture stop operation for adjusting the light amount, the wire spring contacts and slides on the surface near the center of the optical path of the slide pin. , Bias the slide pin,
A diaphragm device, wherein the diaphragm blade can be assembled without contact between the slide pin of the diaphragm blade and the wire spring by assembling the diaphragm blade at a fully open position. The wire spring has a spoiled winding portion, a hook arm connected to one end of the spiral winding portion, and a slide pin abutting arm connected to the other end of the winding portion. claim 1 Symbol placement throttling device. The wire spring has a spoiled winding portion, a hook arm connected to one end of the spiral winding portion, and a slide pin abutting arm connected to the other end,
The cam plate is provided with a spring fulcrum and a spring hook,
The spiral lap winding portions of the wire spring, the engaging said spring fulcrum of the cam plate, the diaphragm according to claim 1 Symbol mounting said hooking arm is characterized in that engaging the spring hook device.

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