JP2909629B2 - Shading blade device for camera - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light shielding blade device used for a shutter or a diaphragm of a still camera. More specifically, if a plurality of blades are arranged so as to be able to travel along a running surface parallel to the opening and are capable of retreating in the opposite direction to the opening, they are sequentially stacked in a plan view. And a light-shielding blade device having a light-shielding blade group.

[Conventional technology]

Recent still cameras, especially compact cameras, are mainly composed of a so-called bifocal camera having two different focal lengths and having a selectable lens, and a so-called zoom camera having a variable focal length lens, and further having a variable focal length. High-magnification zoom cameras with magnifications of 3x and 4x have begun to spread.

By the way, in a zoom camera, since the aperture diameter of the optical path remains almost unchanged, the higher the zoom ratio becomes, the larger the full aperture F value at the long focal length becomes compared to the full aperture F value at the short focal length. System darkens. F at long focus
As the value increases, for example, in the single-lens reflex system, the finder becomes darker. In view of these points, recent compact cameras tend to reduce the F-number of the lens and make the optical system as bright as possible due to market requirements. In order to reduce the F value, the aperture of the lens must be naturally increased if the focal lengths are the same.

In such a compact camera, a light-shielding blade device that slides a pair of light-shielding blades in directions opposite to each other with respect to a lens opening to open and close the opening has been widely used. This type of device can control the opening time and the opening diameter by the blade itself, and is small and lightweight, so that it has been frequently used in compact cameras.

However, in such a light-shielding blade device, when the diameter of the opening is increased, the size of the blade for closing and closing the opening must be necessarily increased. In this case, when the opening is fully opened, the pair of blades are retracted to both sides of the opening. However, since the size of each blade is large, the planar spread of the blades is inevitable and the outer diameter of the light-shielding blade device is increased. There were difficulties. In this type of device, the outer diameter of the light-shielding blade device must be increased substantially in proportion to the inner diameter of the opening. In view of the fact that the outer diameter of the light-shielding blade device substantially defines the size of the entire compact camera, such a problem is significant for the market demand for reducing the lens F value without increasing the size of the compact camera. Was a major obstacle.

In view of the difficulties of the conventional light-shielding blade device described above,
-526 discloses an improved shading vane device. In this type of shading blade device, the inner diameter of the opening can be increased without increasing the outer diameter of the device. That is, in this type of light-shielding blade device, each of a pair of blades, which was conventionally one, is divided into two blades, an outer blade and an inner blade. When the opening is fully closed, the opening is completely closed while overlapping each other. However, when the opening is fully opened, it is stored while overlapping with the annular portion sandwiched between the inner diameter end of the opening and the outer diameter end of the light shielding blade device. That is, in this case, the light-shielding blades originally composed of two sheets are composed of four sheets, and are arranged so as to overlap each other when viewed two-dimensionally.

[Problems to be solved by the invention]

However, the light-shielding blade device disclosed in Japanese Patent Application Laid-Open No. Sho 64-526 has a structure in which four light-shielding blades are rotatably locked by a common rotation shaft around the opening. Each light-shielding blade is moved by four operating pins. Since the four operating pins are arranged close to each other, each light-shielding blade must be provided with a notch in order to avoid the movement trajectory of the dense operating pins, and the shape must be complicated. . For this reason, the outer shape of the light-shielding blade is greatly restricted, which is a problem.

The light-shielding blade group travels so as to retreat left and right from the opening about the common rotation axis. Therefore, the effective opening shape defined by the opposing end portions of the light-shielding blades that are divided into left and right is greatly deviated from a perfect circle and is distorted. For this reason, there has been a problem that it is difficult to accurately control the exposure amount.

[Means to solve the problem]

The present invention has been made in view of the above-described conventional problems, and has as its object to provide an improved light-shielding blade device having light-shielding blades whose shape can be easily designed and having an effective opening shape closer to a perfect circle.

In order to achieve the above object, according to the present invention, a light-shielding blade device is rotatable around a common first fulcrum in a peripheral portion and a substrate formed of a central portion provided with an opening. The first and second sets of main and sub blades that are arranged and can be retracted in one direction from the opening, and the common second fulcrum on the opposite side to the first fulcrum so as to sandwich the opening in the periphery of the substrate And a second set of main and sub blades that can be retracted in the other direction from the opening and are disposed around the substrate, and the first and second sets of blades are interlocked with each other. And an operating mechanism for opening and closing the opening.

Preferably, the first and second fulcrums are arranged at positions substantially symmetric with respect to an optical axis passing through the opening.

The operating mechanism includes a first operating lever for operating the first blade group, a second operating lever for operating the second blade group, and a connecting member that connects the first and second operating levers. Contains.

Further, the operating mechanism has a drive source for directly driving the connecting member.

In addition, the operating mechanism is disposed on the substrate surface opposite to the blade group with respect to the substrate, and includes a regulating member for regulating the floating of the connecting member with respect to the substrate surface.

Preferably, each blade group includes a main blade having a large rotation angle and defining an effective opening, and a sub-blade having a small rotation angle and covering an opening that is not covered by the main blade.

[Action]

According to the present invention, when the opening of the light-shielding blade device is closed, the four light-shielding blades partially overlap each other to completely close the opening. When the operating orbit is operated in this state, the first blade group retreats from the opening in one direction, and the second blade group retreats from the opening in the other direction. As a result, the opening is opened, and the light-shielding blade device shifts to the open state. To return from the open state to the closed state, the operating mechanism is operated in the reverse direction. Through a series of these operations, the opening and closing of the lens opening is performed for each exposure.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1A is a front side plan view of a light-shielding blade device according to the present invention, and shows a closed state of an opening. A first fulcrum shaft 1a and a second fulcrum shaft 1b are implanted in the peripheral portion of the shutter frame or the surface of the substrate 1. A lens opening 1k is formed in the center of the substrate 1. The first and second fulcrum axes 1a and 1b are arranged at substantially symmetric positions with respect to an optical axis passing through the center of the lens aperture 1k. The first fulcrum shaft 1a is rotatably locked with a pair of main and sub first blade groups. The first blade group includes a main blade 2 having a large rotation angle and defining an effective opening, and a sub blade 3 having a large rotation angle and covering an opening that is not covered by the main blade.
It is composed of The second fulcrum shaft 1b is rotatably locked with a pair of main and sub second blade groups. The second blade group similarly includes a main blade 4 and a sub blade 5. The main blades 2 and 4 have the same shape, and the sub blades 3 and 5 also have the same shape. These four blades partially overlap to completely close the lens opening 1k.

The main blade 2 has a long groove 2a at a predetermined distance from the first fulcrum shaft 1a.
Are formed. An operating pin 6a penetrating through the substrate 1 is engaged with the long groove 2a. A long groove 3a is formed in the sub-blade 3 at a predetermined distance from the first fulcrum shaft 1a. An operating pin 6b penetrating the substrate 1 is engaged with the long groove 3a. The main blade 2 and the sub blade 3 are rotated about the fulcrum shaft 1a by the operating pins 6a and 6b. The rotation angle of the main blade 2 is set to be larger than the rotation angle of the sub blade 3. Similarly, the second
An operating pin 7a penetrating through the substrate 1 is engaged with the main blade 4 belonging to the group of blades. A long groove 5a is also formed in the sub-blade 5, and is engaged with an operating pin 7b penetrating the substrate 1. By driving the operating pins 7a and 7b, the main blade 4 and the sub blade 5 are rotated about the second fulcrum shaft 1b. The rotation angle of the main blade 4 is also set to be larger than the rotation angle of the sub blade 5.

A spring 14 is wound around the first fulcrum shaft 1a, and one end of the spring 14 urges the main blade 2 in the closing direction. A spring 15 is wound around the second fulcrum shaft 1b, and one end of the spring 15 urges the main blade 4 in the closing direction.

A tongue 2b is formed on the main blade 2 and covers a window provided on the substrate 1. A light reflection layer is formed on the tongue portion 2b, and a photo sensor 13 is arranged to face the light reflection layer to constitute a reflection type photo interrupter.

A regulating pin 1h is implanted around the surface of the substrate 1 to regulate the rotation of the sub blade 3 in the closing direction. Also control pin 1j
Are also implanted to regulate the rotation of the main blade 4 in the opening direction.

FIG. 1B is a plan view of the surface of the light-shielding blade device according to the present invention, showing an open state of the opening. However, the springs 14 and 15 are omitted for simplicity. As shown in the drawing, the main blade 2 and the sub blade 3 constituting the first blade group are rotated counterclockwise about the first fulcrum shaft 1a by operating pins 6a and 6b, and are opened.
Retreats in one direction from 1k. Then, it is stored in a state of being superposed on the peripheral portion of the substrate 1. The main blade 4 and the sub-blade 5 belonging to the second blade group are similarly rotated counterclockwise about the second fulcrum shaft 1b by the operating pins 7a and 7b. As a result, the substrate 1 is retracted from the opening 1k in the opposite direction, and is stored in a state of being largely overlapped with the peripheral portion of the substrate 1.

FIG. 2A is a plan view of the back surface of the light-shielding blade device, showing the closed state of the opening. That is, it is a view of the substrate 1 shown in FIG. 1A as viewed from the back side. A rotating shaft 1c is implanted around the rear surface of the substrate 1. A first operating lever 6 is rotatably locked to the rotating shaft 1c. Operation pins 6a and 6b are fixed to both ends of the first operation lever 6, and as described above, the operation pins 6a
Penetrates through the substrate 1 and engages with the long groove 2a of the main blade 2 on the front side. The operating pin 6b penetrates through the substrate 1 and engages with the long groove 3a of the sub blade 3. A rotating shaft 1d is implanted in the peripheral portion of the substrate opposite to the first operating lever 6 with respect to the opening 1c. A second operating lever 7 is rotatably locked to the rotating shaft 1d. An operating pin 7a is provided at both ends of the second operating lever 7.
And 7b are fixed. As described above, the operating pin 7a penetrates the substrate 1 and engages with the long groove 4a of the main blade 4, and the operating pin 7b penetrates the substrate 1 and engages with the long groove 5a of the sub blade 5. .

A connection pin 6c is fixed to the first operation lever 6 on a surface opposite to the operation pin. A connecting pin 7c is fixed to the second operating lever 7 on the surface opposite to the operating pin. A connecting member 8 having an arc shape is connected to the connecting pins 6c and 7c. A long groove 8a is formed in the center of the connecting member 8. A drive pin 9a of a drive source (not shown) is provided in the long groove 8a.
Are engaged. The drive pin 9a moves up and down in the figure.

At the periphery of the back surface of the substrate 1, the protrusion 1 is formed along the connecting member 8.
e, 1f and 1g are formed to support the connecting member 8 from below. By driving the drive pin 9a, the connecting member 8 moves up and down, and the first and second operating levers 6 and 7 rotate around the rotation axis in conjunction with each other. That is, the first and second operating levers 6, 7 and the connecting member 8 constitute a so-called parallel link mechanism.

FIG. 2B is a rear plan view of the light-shielding blade device, showing an open state of the opening. That is, it is a view of the substrate shown in FIG. 1B viewed from the back side. As shown, the four light-shielding blades are completely retracted from the opening 1k. In the open state, the connecting member 8 is moved upward by the drive pin 9a, and accordingly, the first and second operating levers 6, 7 rotate clockwise around the corresponding rotation axes 1c, 1d. I do. By this rotation, the operating pins 6a, 6b, 7a, 7b fixed to the operating lever are synchronously displaced,
As described above, the light-shielding blades travel in the opening direction.

FIG. 3A is a sectional view of the light-shielding blade device cut along a straight line passing through the operating pins 6a and 6b. As shown, the light-shielding blade device has a structure in which three surface members are stacked. That is, the upper shutter frame 12 is disposed on the front side of the substrate 1, and the link retainer 10 is disposed on the rear side of the substrate 1. An intermediate plate 11 is inserted between the substrate 1 and the shutter upper frame 12, and the main blade 2 and the sub-blade 3 constituting the first blade group
And the main blade 4 and the sub blade 5 (not shown) constituting the second blade group are separated from each other. By inserting the intermediate plate 11 between the two blade groups, the blades are prevented from interfering with each other during traveling. The main blade 2 and the sub blade 3 are the substrate 1
Are supported by a common fulcrum shaft 1a planted at the center. An operation pin 6a is engaged with the long groove 2a of the main blade 2, and an operation pin 6b is engaged with the long groove 3a of the sub blade 3. A rotating shaft 1c is implanted on the back side of the substrate 1, and rotatably supports the operating lever 6. The connecting member 8 is inserted between the base plate 1 and the link retainer 10 and has one end rotatably engaged with the connecting pin 6c of the operating lever 6 at one end thereof. The connecting member 8 is supported from above and below by a protruding portion 1e provided on the substrate 1 and a protruding portion 10a provided on the link retainer 10, and regulates the floating of the connecting member 8.

Incidentally As mentioned above, the main blade 2 and the sub blade 3 in order to retract from the opening 1k in a state of overlapping the substrate peripheral portion than the rotational angle theta ₁ of the main blade 2 rotating angle theta ₂ of the sub blade 3 Must be bigger. Therefore, as shown in the figure, the rotation shaft 1c of the operating lever 6 is shifted by a predetermined amount toward the operating pin 6b with respect to the fulcrum shaft 1a of the blade, and the shift amount and the positions of the operating pins 6a and 6b are appropriately set to θ. it may be set to _{1> θ 2} satisfies the condition like.

For example, as an example, the distance between the operating pin 6a and the fulcrum shaft 1a is set to 2.
The distance between the operating pin 6b and the fulcrum shaft 1a is set to 3.0 for 5 (same as the relative value). Then, the rotation shaft 1c is implanted with a shift of 1.0 with respect to the fulcrum shaft 1a toward the operation pin 6b. Therefore, the operating pin 6a
The distance between the rotating shaft 1c and the operating pin 6b is set to 3.5, and the distance between the operating pin 6b and the rotating shaft 1c is set to 2.0.

In the setting described above, when the operating lever 6 is driven, when the operating pin 6a for operating the main blade 2 moves by a maximum angle α around the rotation axis 1c, the operating pin 6b for operating the sub-wing 3 also rotates. It moves by an angle α about the axis 1c. At this time, looking around the fulcrum shaft 1a,
6a is closer to the fulcrum shaft 1a than the rotation shaft 1c, so the main blade 2 has an angle α
Rotates at a larger rotation angle theta _1. On the other hand actuating pin 6b is rotated so far from the fulcrum shaft 1a from rotating shaft 1c secondary blade 3 than the angle α at a small rotation angle theta _2. Therefore, the condition of θ ₁ > θ ₂ is satisfied. That is, by appropriately selecting the relative distance between the fulcrum shaft 1a and the rotation shaft 1c, a desired blade rotation angle can be obtained.

FIG. 3B is a sectional view of the light-shielding blade device cut along a straight line connecting the center point of the opening 1k and the drive pin 9a. As shown in the figure, the connecting member 8 is supported from above and below by a flat ring-shaped protrusion 1g provided on the substrate 1 and a protrusion 10b provided on the link retainer 10 to prevent the connection member 8 from floating. ing. A drive pin 9a is engaged with the long groove 8a of the connecting member 8 through the link retainer 10. The drive pin 9a is driven by the drive source 9. As the driving source 9, for example, a stepping motor or a moving magnet actuator is used. The drive source 9 is preferably small, and does not extend outward from the end of the substrate 1.

Next, the operation of the light-shielding blade device according to the present invention will be described.
When the drive source 9 is started in the open state, the drive pin 9a starts moving and drives the connecting member 8. As a result, the first and second operating levers 6 and 7 start to operate in the same direction in conjunction with each other, and the light-shielding blades 2 to 5 run in the opening direction via the operating pins. The first blade group and the second blade group start retreating from the opening 1k in directions opposite to each other. At this time, the photo sensor 13 detects the movement of the tongue 2b of the main blade 2 and generates an open signal. In response to the open signal, a control circuit (not shown) measures the exposure time according to the luminance of the subject, and generates a close signal after the measurement is completed. In response to the close signal, the drive source 9 drives in the reverse direction, moving the drive pin 9a in the reverse direction. As a result, the connecting member 8 is displaced in the opposite direction, and the first and second operating levers 6 and 7 also rotate in the opposite direction in conjunction with each other. as a result,
The light-shielding blades 2 to 5 start running in the closing direction by the operating pins 6a, 6b, 7a, 7b, close the opening 1k, and complete the exposure.

FIG. 4 shows the effective aperture shape of the opening 1k that changes momentarily during the travel of the light-shielding blade in the opening direction. As is clear from the figure, the aperture shape is closer to a perfect circle than the conventional light shielding blade device.

〔The invention's effect〕

According to the present invention, since the first and second blade groups are pivotally supported on opposite sides with respect to the opening, the light-shielding blades can be stored more compactly than a conventional light-shielding blade device. Can do things. In other words, there is an effect that the aperture diameter can be made larger and the substrate outer diameter can be made smaller as compared with the conventional light shielding blade device. In addition, since the first and second blade groups are separately supported, the operating pins for moving the blades can also be separated, and as in the conventional light-shielding blade device, complicated operation is required to avoid the operating pins. There is also an effect that it is not necessary to form a notch having a shape in the light shielding blade. In addition, since the first and second blade groups are arranged symmetrically with respect to the opening, the shape of the effective opening defined by the light-shielding blade is also
There is an effect that the shape can be made closer to a perfect circle as compared with the conventional light shielding blade device.

[Brief description of the drawings]

1A is a plan view of the light-shielding blade device when viewed from the front side, showing an open state, FIG. 1B is a plan view of the light-shielding blade device when viewed from the front side, and FIG. FIG. 2B is a plan view of the light-shielding blade device viewed from the front side, showing an open state of the blade device, and FIG. 3A is a plan view of the light-shielding blade device connecting the set of operating pins. FIG. 3B is a cross-sectional view of the light-shielding blade device cut along a line, FIG. 3B is a cross-sectional view of the light-shielding blade device cut along a line connecting the center of the opening and the drive pin, and FIG. It is a schematic diagram which shows the opening shape of an apparatus. DESCRIPTION OF SYMBOLS 1 ... Board | substrate 2, ... Main blade 3 ... Sub blade, 4 ... Main blade 5 ... Sub blade, 6 ... 1st operating lever 7 ... 2nd operating lever, 8 ... Connection member 9 …… Drive source, 10… Link holder 11 …… Intermediate plate, 12 …… Shutter upper frame 13 …… Photo sensor

Claims (6)

(57) [Claims] 1. A substrate having a peripheral portion and a central portion provided with an opening, and a substrate which is rotatable around a common first fulcrum in the peripheral portion of the substrate, and is retractable in one direction from the opening. A pair of main blades and a first blade group are arranged so as to be rotatable around a common second fulcrum on the opposite side to the first fulcrum so as to sandwich the opening at the periphery of the substrate. A second set of main and sub-blades that can be retracted in the other direction, and an operating mechanism that is arranged around the substrate and operates the first and second sets of blades in an interlocked manner to open and close the opening. Shading blade device. 2. The light-shielding blade device according to claim 1, wherein said first and second fulcrums are arranged at positions substantially symmetric with respect to an optical axis passing through said opening. 3. The operating mechanism includes a first operating lever for operating the first blade group, a second operating lever for operating the second blade group, and first and second operating levers. The light-shielding blade device according to claim 1, further comprising a connecting member to be connected. 4. The light-shielding blade device according to claim 3, wherein said operating mechanism has a drive source for directly driving the connecting member. 5. The operating mechanism according to claim 3, wherein the operating mechanism is disposed on a substrate surface opposite to the blade group with respect to the substrate, and further comprises a regulating member for regulating the floating of the connecting member with respect to the substrate surface. The light-shielding blade device as described in the above. 6. The blade group according to claim 1, wherein each of the blade groups includes a main blade having a large rotation angle and defining an effective opening, and a sub-blade having a small rotation angle and covering an opening not covered by the main blade. Shading blade device.