JPH0540503Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a barrier mechanism that opens and closes an aperture in front of a photographic lens of a camera.

"Prior Art and its Problems" In the past, the camera lens was protected by a removable lens cap, but recently, especially in lens shutter type cameras, a lens cap (barrier) is installed on the camera itself. This is becoming common. Various structures of this barrier mechanism are known, but the conventional ones basically have the following structure:
A barrier that is mechanically unrelated to the photographic lens is provided in front of the photographic lens, and this barrier is biased in either the open or close direction by a spring force or the like, and is operated against this biasing force. The operator performs the closing or opening operation. However, in lens-shutter cameras, where automation is being pursued to the utmost, there is room for improvement in barriers that require manual opening and closing operations.

Against this background, the present applicant has already supported a lens cover tube having an aperture on the front end surface so as to be movable in a straight line between a photography-enabled position and a storage position behind the lens cover tube. A cam ring is provided to move the lens cover tube between the shooting position and the storage position as the lens moves, and a pair of barriers that open and close the aperture are attached to the front end of the lens cover tube. proposed a camera barrier mechanism equipped with a barrier opening/closing mechanism that opens and closes in conjunction with the rotation of the
No. 193229).

However, the barrier mechanisms proposed in these applications bias a pair of barriers in the opening direction by spring means, and when the barriers are closed, the barriers are closed against the spring means. The repulsive force of the spring means is greatest at the closed position. For this reason, when the cam ring rotates to the lens storage position, it is necessary to set a large operating force to be applied to the opening/closing member that rotates the barrier in the closing direction, and if this operating force becomes small for some reason,
There was a risk that the barrier would not be completely occluded. In particular, when the barrier is closed by a spring-loaded opening/closing member, the repulsive force of the spring means to open the barrier is at its maximum in the barrier closed position;
Since the force of the spring means that biases the opening/closing member in the barrier closing direction is minimized, it becomes difficult to set the spring balance or it becomes necessary to increase the size of the spring.

``Purpose of the invention'' Therefore, the present invention provides a barrier mechanism for a camera that urges the barrier in the opening direction and closes the barrier against the urging force at the lens storage position. The purpose of the present invention is to obtain a camera barrier mechanism in which the operating force is constant or increases only to a small extent.

"Summary of the invention" This invention was completed based on the idea that the increase in the repulsive force of the spring that occurs when closing the barrier can be compensated for by increasing the length of the arm of the member that closes the barrier. . In other words, even if the repulsive force of the spring increases, if the length of the arm of the lever that rotates against the spring force increases, the operating force applied to the lever will not increase in proportion to the repulsive force of the spring. It can be constant or constant.

In other words, the present invention supports a lens cover tube having an aperture on the front end surface so as to be movable in a straight line between a shooting position and a storage position rearward, and the lens cover tube is attached to the outer circumference of the lens cover tube as it rotates. A cam ring is installed at the front end of the lens cover tube to move the cover tube between the shooting position and the storage position.
In a camera barrier mechanism including a pair of barriers that open and close an aperture, and a barrier opening/closing mechanism that opens and closes the pair of barriers in conjunction with rotation of the cam ring, the pair of barriers that open and close the aperture;
a spring means for biasing the pair of barriers in the opening direction; an opening/closing pin having a pair of driving arms and movable back and forth in the radial direction of the lens cover tube; and a driven arm at one end of each of the pair of driving arms of the opening/closing pin. a pair of intermediate levers, the other end of which is engaged with the pair of barriers; when the lens cover tube is retracted to the storage position, the opening/closing pin is pressed against the spring means; a barrier closing means for closing the barrier, and a pair of drive arms of an opening/closing pin;
The driven arm of the pair of intermediate levers is characterized in that as the opening/closing pin moves in the barrier closing direction, the point of application of the force moves away from the axis of the intermediate lever.

According to this configuration, as the barrier progresses, the length of the arm of the intermediate lever that is pressed by the drive arm of the opening/closing pin increases. can be kept constant.

``Embodiments of the invention'' The invention will be described below with reference to illustrated embodiments. In this embodiment, the present invention is applied to a lens shutter camera having a zoom lens. First, referring to FIG. 4, the overall structure of a zoom lens shutter camera having a barrier mechanism 30 according to the present invention will be described. A fixing tube 13 is fixed to the front surface of the body main body 11 via a fixing screw 12.
An inner rail 11a and an outer rail 11b are provided on the rear surface of the body main body 11, and a pressure plate 15 provided on the back cover 14 comes into contact with the outer rail 11b.
5 and the inner rail 11a. A finder optical system 16 is provided on the upper part of the body main body 11, and the outside of the main body 11, the finder optical system 16, and the fixed barrel 13 are covered by a camera main body case 17.

A cam ring 20 is fitted into the inner periphery of the fixed barrel 13 so as to be rotatable and movable in the optical axis direction. The cam ring 20 has cam grooves 20a and 20b for moving the front and rear lens groups L1 and L2 along a predetermined trajectory in the optical axis direction. The pin 23a implanted in the hole is fitted into the pin 23a. This pin 23a is further connected to the fixed cylinder 13.
The front group cam ring driven ring 23 is fitted into a linear guide groove 13a formed in the optical axis direction, and restricts rotation of the front group cam ring driven ring 23, allowing movement only in the optical axis direction.

The front group cam ring driven ring 23 is provided with a guide pin 23b parallel to the optical axis.
A rear group cam ring driven ring 24 to which the rear group lens L2 is fixed is movably supported at b. A pin 24a is installed in the rear group cam ring driven ring 24.
is the clearance groove 2 formed in the front group cam ring driven ring 23.
3c, and is fitted into the cam groove 20b of the cam ring 20.

A lens shutter unit 25 is fixed to the front part of the front group cam ring driven ring 23, and a helicoid 25 is attached to the lens shutter unit 25.
A front group lens ring 26 to which the front group lens L1 is fixed is screwed together by b and 26c. The lens shutter unit 25 moves its drive pin 25a by an angle corresponding to a distance measurement signal from a distance measurement device (not shown).
The drive pin 25a is engaged with an interlocking arm 26a fixed to the front group lens ring 26. Therefore, the front group lens ring 26 moves in the optical axis direction according to the rotation angle of the drive pin 25a, and the focus is adjusted.

The cam ring 20 is rotationally driven via a gear train and a drive motor (not shown). When the cam ring 20 rotates, the front group cam ring driven ring 23, that is, the front group lens L1 moves in the optical axis direction according to the cam groove 20a and the linear guide groove 13a, and the rear group cam moves according to the cam groove 20b. Ring driven ring 24, that is, rear group lens L
2 moves in the optical axis direction while maintaining the air distance with the front lens group L1 at a set value, and zooming is performed.
Further, when the cam ring 20 rotates to one rotation end, the lens groups L1 and L2 move from the photographing position to the retracted storage position.

A back adjustment mechanism is provided between the cam ring 20 and the fixed cylinder 13. On the outer periphery of the cam ring 20,
A circumferential groove 27 is formed, and this circumferential groove 2
7, a thrust member 28 supported by the fixed cylinder 13 so as to be movable in the optical axis direction is fitted. Therefore, by adjusting the position of the thrust member 28 in the optical axis direction, the position of the cam ring 20, that is, the position of the front group and rear group lenses L1 and L2, is adjusted, and the focus surface is accurately aligned with the film surface. Back adjustment is possible. After the back adjustment, the thrust member 28 is fixed to the fixed cylinder 13 with a fixing screw 29.

A lens cover tube 31 is fixed to the front group cam ring driven ring 23 of the lens shutter camera described above, and an aperture frame 32 having an aperture 32a is joined to the front surface of the lens cover tube 31. In addition, on the inner circumference of the lens cover tube 31,
A barrier ring 33 is fixed, and a barrier mechanism 30, which is a feature of the present invention, is supported on the front and rear surfaces of this barrier ring 33.

1 to 3 show examples thereof. 1 and 2 are sectional views taken along the - line in FIG. 4, and are views of the barrier mechanism 30 seen from the rear. The front side of the barrier ring 33 has an aperture 3
A pair of barriers 34 for opening and closing 2a are pivotally connected by pins 35. The pair of barriers 34, 34 are symmetrically opposed and have a barrier plate portion 34a projecting into the aperture 32a, and a driven arm portion 34b extending in substantially perpendicular relation to the barrier plate portion 34a with respect to the pin 35. are doing.

This driven arm portion 34b has a working pin 36 that protrudes from the back surface of the barrier ring 33 through the through hole 33a.
A pair of elastic legs 3 of a single wire spring member 37 are installed on the outside of the pair of working pins 36.
7a is engaged, and the barrier plate portion 34a rotationally urges the barrier 34 in the direction to open the aperture 32a. Therefore, the barrier 34 always opens the aperture 32a when no external force is applied thereto.

The wire spring member 37 is made of a metal material,
The central U-shaped portion 37b is connected to the barrier ring 33.
It is locked to a support pin 38 implanted in the. This wire spring member 37 has no change in spring force due to environmental changes such as temperature and humidity, and hardly changes over time.
Therefore, a force in the opening direction can always be applied to the barrier 34 with a stable force.

The working arms 3 of a pair of left and right intermediate arms 39 for opening the barrier 34 against the force of the wire spring member 37 are located inside the working pins 36 of the driven arm portions 34b.
9a is engaged. This pair of intermediate arms 39
are connected to the barrier ring 33 by pins 40, respectively.
The operating arm 39a is pivotally connected to the pin 40.
A pair of driven arms 39b extending in the opposite direction are engaged with both drive arms 41a of the opening/closing pin 41.

A pair of drive arms 41a of the opening/closing pin 41 extend in a direction parallel to the radial direction of the cam ring 20, and have pointed tips, and a driven arm 39b extends in a direction parallel to the radial direction of the cam ring 20.
When the drive arm 4 is open, the drive arm 41a has a shape that makes contact with the drive arm 41a at a substantially right angle. FIG. 3 is a skeleton representation of the relationship between the opening/closing pin 41 and the intermediate lever 39.

This opening/closing pin 41 is movably guided in the radial direction of the barrier ring 33 by a guide tube 42 fixed to the barrier ring 33, and its head is inserted into an interlocking square hole 43 drilled in the lens cover tube 31. It's coming. When no external force is applied to the opening/closing pin 41, the spring force of the wire spring member 37 causes the opening/closing pin 41 to
Located at the radially protruding end. Note that the wire spring member 3
7 and the intermediate arm 39 are provided on the back side of the barrier ring 33.

The lens cover tube 3 is attached to the front end surface of the cam ring 20 which is located on the outer periphery of the lens cover tube 31 and is rotationally driven.
A notch 45 is formed which matches the position of the interlocking square hole 43 when the housing 1 moves to the storage position. Further, a closing lever 47 is pivotally connected to the fixed cylinder 13 by a shaft 46, and this closing lever 47 is operated by a torsion spring 48 provided on the shaft 46, so that its operating end 47 is pivoted.
7a enters the inside of the lens cover tube 31 through the interlocking square hole 43 and is urged to press and move the opening/closing pin 41. The cam ring 20 is the lens cover tube 3
1, and the notch 45 is provided in a part thereof. Therefore, the operating end 47a of the closing lever 47 is moved from the notch 45 to the interlocking square hole only when the position matches the notch 45. 43, and at other times, is held in a position where it does not enter into the interlocking square hole 43 by the outer circumferential surface of the cam ring 20. The positions of the notch 45 and the active end 47a of the closing lever 47 are configured to match only when the lens cover cylinder 31 is retreated to the storage position.

Therefore, when the cam ring 20 is rotated from the rotation end of the lens storage position to the photographing possible position, the barrier mechanism 30 having the above-mentioned structure has a structure in which the end 45a of the notch 45
lifts the closing lever 47 against the force of the torsion spring 48 and causes the working end 47 to touch the outer peripheral surface of the cam ring 20.
a into sliding contact. In this state, no barrier closing force is applied to the opening/closing pin 41, so the wire spring member 3
The force of 7 causes the barrier 34 to open (FIG. 1).

After photographing, when the cam ring 20 is rotated to the lens storage position, the working end 47a enters into the notch 45 from the outer peripheral surface of the cam ring 20, and further into the interlocking square hole 43. Then, the opening/closing pin 41 is pressed by the force of the torsion spring 48, and the left and right drive arms 41a
presses the driven arms 39b of the pair of intermediate arms 39 to rotate them against the force of the wire spring member 37. Therefore, the pair of barriers 34 rotate around the pin 35, and the barrier plate portions 34a close (the first
figure).

In the process of closing the barrier, the opening/closing pin 41
is pushed and displaced by the closing lever 47, the contact point (force application point) of the driving arm 41a with the driven arm 39b changes outward away from the pin 40, and the arm of the driven arm 39b becomes substantially longer. . FIG. 3 shows this situation. When the opening/closing pin 41 changes from the solid line to the chain line position in the figure, the arm length of the driven arm 39b of the intermediate lever 39 increases from a to a'.
In contrast, the arm length of the working arm 39a (pin 40
to the operating pin 36) is maintained at a substantially constant b, the operating force F applied to the opening/closing pin 41
Although the repulsive force of the wire spring member 37 increases, it is possible to keep it constant or suppress its increase. That is, if the opening/closing pin 41 is pressed and displaced with the same force F, the force trying to open the barrier 34 via the intermediate arm 39 is
becomes larger as it is displaced inward, and is matched with the repulsive force of the wire spring member 37, which increases as the barrier 34 opens. As a result, a barrier opening/closing mechanism in which the force for operating the opening/closing pin 41 changes little is obtained, and it becomes possible to use a strong spring as the wire spring member 37 or a weak spring as the torsion spring 48.

Note that even if the arm length b of the intermediate lever 39 increases as the barrier is closed, the arm length a increases to a greater extent (a relationship in which a/b increases). If so, the present invention is valid.

In the above embodiment, the opening/closing pin 41 is moved in the barrier closing direction by the spring-biased torsion spring 48, but for example, the cam ring 20
The barrier may be moved in the barrier closing direction by a part of the barrier or by a closing member interlocked therewith.

"Effects of the invention" As described above, the barrier mechanism of the camera of this invention is
In a camera barrier mechanism that biases the barrier in the opening direction and closes the barrier against the biasing force at the lens storage position, the relationship between the opening/closing pin for closing the barrier and the intermediate lever is determined by the pair of driving arms of the opening/closing pin. and the driven arms of the pair of intermediate levers are arranged so that as the opening/closing pin moves in the barrier closing direction, the point of application of force is moved away from the axis of the intermediate lever, so that the change in the operating force applied to the opening/closing pin is small or constant. A barrier mechanism for the camera can be obtained. Therefore, especially when spring-biasing the opening/closing pin in the barrier closing direction, it becomes easy to set the spring balance, or the spring can be made smaller, and as a result,
A barrier mechanism that reliably closes is obtained.

[Brief explanation of drawings]

1 to 3 show a first embodiment of a camera barrier mechanism according to the present invention, in which FIG. 1 shows the barrier in an open state, and FIG. 2 shows a fourth embodiment in which the barrier is in a closed state.
FIG. 3 is a sectional view taken along the line of FIG. 3, and is a skeleton diagram showing the relationship between the opening/closing pin and the intermediate lever. Fourth
The figure is a sectional view showing the entire lens shutter type camera equipped with a camera barrier mechanism according to the present invention. 13...Fixed barrel, 20...Cam ring, 30...Barrier mechanism, 31...Lens cover tube, 32...Aperture frame, 32a...Aperture, 33...Barrier ring, 34...Barrier, 35, 40 ... Pin, 37 ... Wire spring member, 39 ... Intermediate arm,
39a... Working arm, 39b... Driven arm, 41...
Opening/closing pin, 41a... Drive arm, 43... Interlocking square hole, 45... Notch, 46... Shaft, 47... Closing lever, 48... Torsion spring.

Claims (1)

[Scope of Claim for Utility Model Registration] A lens cover tube having an aperture on its front end face is supported so as to be movable in a straight line between a photographing position and a storage position behind this, and a lens cover tube having an aperture attached to the outer periphery of the lens cover tube as it rotates. A cam ring is disposed to move the lens cover tube between a shooting position and a storage position, and a pair of barriers for opening and closing the aperture are provided at the front end of the lens cover tube, and the pair of barriers are connected to the cam ring. A camera barrier mechanism is provided with a barrier opening/closing mechanism that opens and closes in conjunction with the rotation of the aperture, and the barrier opening/closing mechanism includes a pair of barriers that open and close the aperture; means; an opening/closing pin having a pair of driving arms and movable back and forth in the radial direction of the lens cover cylinder; one end of each of the pair of driving arms of the opening/closing pin is engaged with a driven arm, and the other end of the operating arm is connected to a pair of barriers; a pair of intermediate levers that respectively engage the lens cover tube; and barrier closing means that presses the opening/closing pin against the spring means and closes the barrier via the intermediate lever when the lens cover tube is retreated to the storage position; The pair of driving arms of the opening/closing pin and the driven arms of the pair of intermediate levers are formed in such a shape that the point of application of the opening/closing pin is moved away from the pivot of the intermediate lever as the opening/closing pin moves in the barrier closing direction. Features a camera barrier mechanism.