JPH0389330A - Light shielding blade device for camera - Google Patents

Abstract

PURPOSE:To make the shape of an effective aperture which is regulated by a light shielding blade closer to a circle by constituting 1st and 2nd blade groups so that they may be pivotally supported on opposite sides each other with respect to the aperture. CONSTITUTION:When a driving source 9 is started in a state where the aperture is closed, a driving pin 9a starts to move and drives a coupling member 8. Then, 1st and 2nd actuation levers 6 and 7 start to actuate interlockingly in the same direction to make the light shielding blade 2 or 5 travel in an opening direction through an actuation pin. In such a case, the 1st and the 2nd blade groups start to retreat from the aperture 1k in a direction opposite to each other. At this time, a photosensor 13 detects the movement of the tongue part 2b of the main blade 2 and generates an opening signal, and a control circuit measures the exposing time in accordance with the brightness of object and generates a closing signal after completing the measurement. In response to the closing signal, the driving source 9 drives in a reverse direction to move the driving pin 9a in the reverse direction and the coupling member 8 displaces in the reverse direction, then the 1st and the 2nd actuation levers 6 and 7 rotate in the reverse direction interlockingly and shield the lens aperture 1k, thereby completing the exposure. Thus, the shape of aperture becomes closer to a circle.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a light shielding blade device used for a shutter or an aperture of a still camera. More specifically, it is arranged so that it can run along a running surface parallel to the opening, and consists of a plurality of blades that can be retracted in opposite directions relative to the opening, and are stacked one on top of the other in a plan view. The present invention relates to a shading blade device having a group of shading blades.

[Conventional technology]

Modern still cameras, especially compact cameras, have two different types.
The main products are so-called bifocal cameras, which have two focal lengths and a selectable lens, and so-called zoom cameras, which have a variable focal length lens, and also have a variable focal length magnification of 3x.

High-power zoom cameras with 4x zoom are becoming popular.

By the way, in a zoom camera, the aperture diameter of the optical path remains almost unchanged, so the higher the zoom ratio, the larger the full-open F-number at a long focus becomes, compared to the full-open F-number at a short focus. The system becomes dark. When the F number at long focal length increases, for example, in the case of an eye reflex system, the finder becomes dark. In view of these points, there is a trend in recent compact cameras to make the optical system as bright as possible by reducing the F value of the lens due to market demands. In order to reduce the F number, if the focal length remains the same, the aperture of the lens must naturally be increased.

In such compact cameras, a light-shielding blade device in which a pair of light-shielding blades are slid in opposite directions relative to a lens aperture to open and close the aperture has been widely used. This type of device can control the aperture time and aperture diameter by the blade itself, and is small and lightweight, so it has been widely used in compact cameras.

However, in such a light-shielding blade device, when the aperture diameter is increased, it is necessary to increase the size of the blade for blocking and closing the aperture. In this case, when the aperture is fully opened, the pair of blades are retracted to both sides of the aperture, but since the dimensions of each blade are large, the planar spread of the blades becomes obvious, and the outer diameter of the light-shielding blade device increases. There was a problem. In this type of device, the outer diameter of the light-shielding blade device must be increased approximately in proportion to the inner diameter of the opening. Considering that the outer diameter of the light-shielding blade device substantially determines the overall size of the compact camera, this difficulty is critical to the market demand for reducing the lens F value without increasing the size of the compact camera. This was a major hindrance.

In view of the above-mentioned drawbacks of the conventional light-shielding blade device, Japanese Patent Laid-Open No. 1984
JP-A-528 discloses an improved light-shielding blade device. In this type of light-shielding 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 the pair of blades, which was conventionally one blade, is divided into two blades, an outer blade and an inner blade, and when the aperture is fully opened, they overlap each other and completely close the aperture. When the aperture is fully open, it is accommodated while overlapping the ring-shaped portion sandwiched between the inner diameter end of the aperture and the outer diameter end of the light shielding blade device. That is, the light-shielding blades, which are originally composed of two pieces, in this case are composed of four pieces, and are arranged so as to overlap each other when viewed from above.

[Problems to be solved by the invention]

However, the light-shielding blade device disclosed in Japanese Patent Application Laid-open No. 84-526 has a structure in which four light-shielding blades are rotatably locked around the periphery of the opening by a common rotating shaft. Each light shielding blade is driven by four operating pins.

Since the four actuation pins are placed close to each other,
Each light-shielding blade had to be provided with a notch in order to avoid the movement locus of the densely packed operating pins, and had to have a complicated shape. For this reason, the external shape of the light-shielding blades was severely restricted, which caused problems.

Further, the light shielding blade group runs so as to retreat from the opening to the left and right around a common rotation axis. Therefore, the effective aperture shape defined by the opposing ends of the left and right light shielding blades is greatly deviated from a perfect circle and is distorted. For this reason, there was a problem in that it was difficult to accurately control the exposure amount.

[Means for solving problems]

In view of the above-mentioned conventional problems, an object of the present invention is to provide an improved light-shielding blade device that has light-shielding blades whose shape is easy to design and whose effective opening shape is closer to a perfect circle.

In order to achieve the above object, according to the present invention, a light shielding blade device includes a substrate including a peripheral portion and a central portion provided with an opening;
A main and sub-pair of blades that are rotatably arranged around a common first fulcrum in the peripheral area of the board and can be retracted in one direction from the opening; A second group of main and sub blades is arranged to be rotatable about a common second fulcrum on the opposite side of the board and can be retracted in the other direction from the opening, and It is composed of an operating mechanism that operates the first and second groups of blades in conjunction with each other to open and close the opening.

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

The actuation mechanism also includes a first actuation lever for actuating the first blade group, a second actuation lever for actuating the second blade group, and a mechanism for connecting the first and second actuation levers. It includes a connecting member. Furthermore, the actuation mechanism has a drive source for directly driving the connecting member. In addition, the actuation mechanism is disposed on the substrate surface opposite to the blade group, and includes a regulating member for regulating floating of the connecting member with respect to the substrate surface.

Preferably, each blade group is composed of a main blade that has a large rotation angle and defines an effective opening, and a sub blade that has a small rotation angle and covers the opening portion that is not covered by the main blade.

[For production]

According to the present invention, when the opening of the shading blade device is in the closed state, the four shading blades partially overlap each other to completely block the opening. When the actuation mechanism is operated in this state, the first group of blades retreats from the opening in one direction, and the second group of blades retreats from the opening in the other direction. As a result, the aperture is opened and the light shielding blade device is moved to the open state. To return from the open state to the closed state, the operating mechanism is operated in the opposite direction. Through this series of operations, the lens aperture is opened and closed for each exposure.

〔Example〕

Preferred embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1A is a top plan view of the light shielding blade device according to the present invention, showing the opening and closed state. , a first fulcrum shaft 1a and a second fulcrum shaft 1b are implanted in the periphery of the shirt frame or the surface of the substrate 1.

Further, a lens opening 1k is formed in the center of the substrate 1. The first and second fulcrum axes 1 a and 1 b are arranged at substantially symmetrical positions with respect to the optical axis passing through the center of the lens aperture 1 . A primary and secondary blade group is rotatably secured to the first fulcrum shaft 1a.

The first blade group is composed of a main blade 2 that has a large rotation angle and defines an effective opening, and a sub blade 3 that has a small rotation angle and is used to cover the opening portion that is not covered by the main blade. Further, a second group of main and sub blades is rotatably secured to the second fulcrum shaft 1b. The second blade group is similarly composed of main blades 4 and sub blades 5. The main blades 2 and 4 have the same shape,
The sub-wings 3 and 5 also have the same shape. These four blades partially overlap to completely block the lens aperture 1k.

The main blade 2 has a long groove 2 at a predetermined distance from the first fulcrum shaft 1a.
a is formed. An operating pin 6a that passes through the substrate 1 is engaged with the long groove 2a. Further, a long groove 3a is formed in the sub-wing 3 at a predetermined distance from the first fulcrum shaft 1a. An operating pin 6b that passes through 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 these 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, an operating pin 7a that penetrates the substrate 1 is engaged with the main blade 4 belonging to the second blade group. Secondary blade 5
A long groove 5a is also formed in the base plate 1, and engages with an actuating pin 7b passing through the substrate 1. By driving the operating pins 7a and 7b, the main blade 4 and the secondary blade 5 are moved to the second fulcrum shaft 1.
It is rotated around b. The rotation angle of the main blade 4 is also set 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 biases the main blade 2 in the closing direction. Also, the second fulcrum shaft 1
A spring 5 is wound around b, and one end of the spring 5 urges the main blade 4 in the closing direction.

A tongue portion 2b is formed on the main blade 2 and covers a window provided in the substrate 1. A light-reflecting layer is formed on the tongue portion 2b, and a photosensor 13 is arranged opposite to this light-reflecting layer to constitute a reflective photointerrupter.

A regulating pin 1h is implanted around the surface of the substrate 1 to regulate the rotation of the sub-side plate 3 in the closing direction.

A restriction bottle 1j is also installed to restrict the rotation of the main blade 4 in the opening direction.

FIG. 1B is a surface plan view of the light shielding blade device according to the present invention, showing the aperture open state. However, for simplicity, the springs 14 and 15 are omitted. As shown in the figure, the main blade 2 and the secondary side plate 3 constituting the first blade group are rotated counterclockwise by actuating pins 6a and 6b about the first fulcrum shaft 1a, and are rotated in one direction from the opening 1k. They are evacuating. and board 1
It is stored in an overlapping state around the periphery of the Further, the main blade 4 and the sub-side plate 5 belonging to the second blade group are similarly rotated counterclockwise about the second fulcrum shaft 1b by operating pins 7a and 7b. As a result, it retreats from the opening 1k in the opposite direction and is stored in the peripheral portion of the substrate 1 in a mostly shaped state.

FIG. 2A shows a back plan view of the light-shielding blade device, showing the open and closed state. That is, this is a view of the substrate 1 shown in FIG. 1A viewed from the back side. A rotating shaft 1c is implanted around the back surface of the substrate 1. A first operating lever 6 is rotatably locked to the rotating shaft IC.

At both ends of the first actuating lever 6 are actuating pins 6a and 6b.
As mentioned above, the actuating pin 6a penetrates the base plate 1 and engages with the long groove 2a of the main blade 2 on the front side. Further, the actuating pin 6b penetrates the base plate 1 and engages with the long groove portion 3a of the sub-side plate 3.

A rotating shaft 1d is implanted around the substrate on the opposite side of the first operating lever 6 with respect to the opening 1c. A second operating lever 7 is rotatably locked to the rotating shaft 1d. Operating pins 7a and 7b are fixed to both ends of the second operating lever 7. As mentioned 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-side plate 5.

A connecting pin 6C is fixed to the first actuating lever 6 on the side opposite to the actuating pin. A connecting pin 7C is fixed to the second operating lever 7 on the opposite side of the operating pin.

A connecting member 8 having an arc shape is connected to these connecting pins 6C and 7c. A long groove 8 is provided in the center of the connecting member 8.
a is formed. A drive pin 9a of a drive source (not shown) is engaged with the long groove 8a. The drive pin 9a moves in the vertical direction in the figure.

A protrusion 1 is provided along the connecting member 8 on the periphery of the back surface of the substrate 1.
e+1f and 1g are formed and support the connecting member 8 from below. By driving the drive bin 9a, the connecting member 8 is moved in the vertical direction, and the first and second operating levers 6.7 are interlocked and rotated around the rotation axis. That is, the first and second actuating levers 6.7 and the connecting member 8 constitute a so-called parallel link mechanism.

′! Figure s2B is a back plan view of the light-shielding blade device, showing the aperture open state. That is, this is a view of the substrate shown in FIG. 1B from the back side. As shown in the figure, 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 the first and second operating levers 6.7 are accordingly rotated clockwise around the corresponding rotation axes 1c and 1d. do. Due to this rotation, the actuation pins 6a, 6b fixed to the actuation lever
, 7a, and 7b are synchronously displaced, and the light shielding blades are moved in the opening direction as described above.

FIG. 3A is a cross-sectional view of the light-shielding vane device taken along a straight line passing through the actuating pins 6a and 6b.

As shown in the figure, the light-shielding blade device has a structure in which three surface members are stacked one on top of the other. That is, the shutter upper frame 1 is placed on the front side of the board 1.
2 is arranged, and a link presser 1 is placed on the back side of the board 1.
0 is placed. An intermediate plate 11 is inserted between the substrate 1 and the shutter upper frame 2, and includes the main blade 2 and secondary side plate 3 forming the first blade group, and the main blade 4 and secondary side plate forming the second blade group. 5 (not shown) from each other.

By inserting this intermediate plate 11 between both blade groups, the blades are prevented from interfering with each other during travel. The main blade 2 and the sub blade 3 share a common fulcrum shaft 1a implanted in the base plate 1.
It is pivoted by. An operating pin 6a is engaged with the long groove 2a of the main blade 2, and an operating pin 6b is engaged with the long groove 3a of the sub blade 3. There is a rotating shaft 1c on the back side of the board 1.
is installed, and rotatably supports the operating lever 6. The connecting member 8 is inserted between the base plate 1 and the link presser lO, and is rotatably engaged with the connecting pin 6c of the operating lever 6 at one end thereof. The connecting member 8 is the substrate 1
It is supported from above and below by a protrusion 1e provided on the link holder IO and a protrusion 10a provided on the link presser IO, thereby restricting the floating of the connecting member 8.

By the way, as mentioned above, in order to retract the main blade 2 and the secondary blade 3 from the opening 1k while overlapping the peripheral part of the substrate, the rotation angle θ1 of the main blade 2 is made larger than the rotation angle θ2 of the secondary blade 3. There must be. For this reason, as shown in the figure, the rotation axis 1c of the actuation lever 6 is connected to the actuation pin 6b with respect to the fulcrum axis 1a of the blade.
Shift a predetermined amount to the side, and compare the shift amount and the operating bins 6a and 6b.
The condition of θ1>θ2 may be satisfied by appropriately setting the position of .

For example, the distance between the operating bin 6a and the fulcrum shaft 1a is set to 2.5 (relative values are the same), and the distance between the operating bin 6b and the fulcrum shaft 1a is set to 3.0. Then, the rotating shaft 1c is offset by i60 toward the operating pin 6b with respect to the fulcrum shaft 1a and installed. Therefore, the distance between the operating bin 6a and the rotating shaft 1c is 3.5,
Further, the distance between the operating bin 6b and the rotating shaft 1c is set to 2.0.

Now, in the above-mentioned setting, when the operating lever 6 is driven, the operating pin 6a that operates the main blade 2 is
When the actuating pin 6b that operates the sub-blade 3 moves by an angle α at the maximum about the rotating shaft 1c, the actuating pin 6b moves by an angle α about the rotating shaft 1c. At this time, if you look at the fulcrum axis 1a as the center,
Since the operating bin 6a is closer to the fulcrum axis 1a than the rotation axis 1c, the main blade 2 rotates at a rotation angle θ1 larger than the angle α.

On the other hand, since the operating pin 6b is farther from the fulcrum shaft 1a than the rotating shaft 1c, the sub-wing 3 rotates at a rotation angle θ2 smaller than the angle α. Therefore, the condition 01>θ2 is satisfied. That is, by appropriately selecting the relative distance between the fulcrum shaft 1a and the rotating shaft 1c, a desired blade rotation angle can be obtained.

FIG. 3B is a sectional view of the light-shielding blade device taken along a straight line connecting the center point of the opening 1 and the drive bin 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 tab provided on the link presser 10, thereby preventing the connecting member 8 from floating. ing. A driving pin 9a is engaged with the long groove 8a of the connecting member 8 through the link presser lO.

The drive bin 9'a is driven by the drive source 9. For example, a stepping motor or a moving magnet actuator is used as the driving source. The drive source 9 is preferably small and does not protrude outward from the edge of the substrate 1.

Next, the operation of the light shielding blade device according to the present invention will be explained. When the drive source 9 is started in the open/closed state, the drive bin 9a starts moving and drives the connecting member 8. As a result, the first and second operating levers 6 and 7 start operating in the same direction in conjunction with each other, causing the light shielding blades 2 to 5 to travel in the opening direction via the operating bin. The first blade group and the second blade group begin to retreat from the opening 1k in mutually opposite directions. At this time, the photosensor 13 detects the movement of the tongue portion 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 brightness 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 opposite direction, causing the drive bin 9a to move in the opposite direction. As a result, the connecting member 8 is displaced in the opposite direction, and the first and second operating levers 6 and 7 are also rotated in the opposite direction in conjunction with each other. As a result, the working bins 6a, 6b, 7a, 7b
As a result, the light-shielding blades 2 to 5 start traveling in the closing direction, shielding the aperture 1k, and completing the exposure.

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

〔Effect of the invention〕

According to the present invention, since the first and second blade groups are pivoted on opposite sides of the opening, the light shielding blades can be stored more compactly than in conventional light shielding blade devices. I can do things. In other words, compared to the conventional light shielding blade device, there is an effect that the opening diameter can be made larger and the outer diameter of the substrate can be made smaller. In addition, by separately supporting the first and second blade groups, the operating pin for driving the blades can also be separated, and unlike conventional light-shielding blade devices, complicated operation pins are required to avoid the operation pin. Another advantage is that there is no need to form a shaped cutout in the light shielding blade. In addition, since the first and second blade groups are arranged symmetrically with respect to the aperture, the shape of the effective aperture defined by the shading blades is also more perfectly circular than in conventional shading blade devices. This has the effect of making it possible to make it similar.

[Brief explanation of drawings]

FIG. 1A is a plan view of the light-shielding blade device as viewed from the front side, showing the aperture open state, FIG. 1B is a plan view of the light-shielding blade device as seen from the front side, showing the aperture closed state, and FIG. A plan view of the light-shielding blade device seen from the back side showing the opening state, Figure 2B
3A is a plan view of the light shielding blade device as seen from the back side, showing the open state, FIG. 4 is a cross-sectional view of the light shielding blade device taken along a line connecting the center of the opening and the drive pin, and FIG. 4 is a schematic diagram showing the shape of the opening of the light shielding blade device. 1... Board 2... Main blade 3... Sub blade 4... Main blade 5... Sub blade
6... First operating lever 7... Second operating lever 8... Connecting member 9... Drive source 1
0...Link presser 11...Intermediate plate 12
...Shutter upper frame 13...Photo sensor Applicant: Kobal Co., Ltd. Figure 1 Figure 2 A 00 Rotation axis Figure 2 B Figure 3 A

Claims (1)

[Claims] 1. A substrate consisting of a peripheral portion and a central portion provided with an opening, and a substrate that is arranged rotatably about a common first fulcrum in the peripheral portion of the substrate, and is arranged in one direction from the opening. A first group of retractable main and sub blades are arranged rotatably around a common second fulcrum located on the opposite side of the first fulcrum with respect to the opening in the periphery of the board, and A light shielding device consisting of a second group of main and sub blades that can be retracted in the direction, and an operating mechanism that is arranged around the substrate and operates the first and second groups of blades in conjunction to open and close the opening. vane device. 2. The light shielding blade device according to claim 1, wherein the first and second fulcrums are arranged at substantially symmetrical positions with respect to the optical axis passing through the aperture. 3. The actuation mechanism connects a first actuation lever for actuating the first blade group, a second actuation lever for actuating the second blade group, and the first and second actuation levers. The light-shielding blade device according to claim 1, further comprising a connecting member for the light-shielding blade. 4. The light-shielding blade device according to claim 3, wherein the actuation mechanism includes a drive source for directly driving the connecting member. 5. The light-shielding blade according to claim 3, wherein the actuation mechanism is disposed on the substrate surface opposite to the blade group with respect to the substrate, and further includes a regulating member for regulating floating of the connecting member with respect to the substrate surface. Device. 6. The light-shielding blade according to claim 1, wherein each blade group comprises a main blade with a large rotation angle to define an effective opening, and a sub blade with a small rotation angle to cover the opening portion not covered by the main blade. Device.