JP2003195389A - Blade driving mechanism for camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blade driving mechanism having a suitable blade supporting constitution and used for a camera. <P>SOLUTION: Five aperture blades 3 are interposed between a first driving ring 1 and a second driving ring 2. A pin 4a provided to one surface of each aperture blade 4 is engaged with each circular hole 1a of the first driving ring 1. A pin 4b provided to the other surface of each aperture blade 4 is engaged with each long hole 2a of the second driving ring 2. In a two-step gear 5, a large-diameter gear 5b is interlocked with the tooth part 1b of the first driving ring 1; a small-diameter gear 5c is engaged with the tooth part 2b of the second driving ring 2. Consequently, rotating the two-stage gear 5 clockwise rotates the first driving ring 1 and the second driving ring 2 counterclockwise simultaneously and at different speeds. Rotating each of the aperture blades 4 counterclockwise diaphragms each of the aperture blades 4 to a prescribed aperture. This constitution entails high rotation in the driving rings 1, 2 even if each long hole 2a is short. The result conducts with good accuracy multi-stage control for the diaphragmed aperture. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive ring that reciprocally rotates about an optical axis and simultaneously rotates a plurality of diaphragm blades or shutter blades in the same direction to open and close an exposure aperture. The present invention relates to a camera blade drive mechanism.

[0002]

2. Description of the Related Art An example of a camera blade drive mechanism in which a drive ring that reciprocally rotates about an optical axis simultaneously rotates a plurality of blades in the same direction is disclosed in Japanese Patent Laid-Open No. 2001-20.
It is described in Japanese Patent No. 1780. The camera blade drive mechanism can be implemented as both a shutter blade drive mechanism and an aperture blade drive mechanism, but the embodiment is described as an aperture blade drive mechanism. Then, in the case of the embodiment, each of the six diaphragm blades rotatably fits a pin provided on one surface into a circular hole formed in the base plate and provided on the other surface. The pin is fitted into a long hole (cam groove) formed in the drive ring, and the drive ring is reciprocally rotated by the motor, so that the six aperture blades are simultaneously rotated in the same direction to expose the exposure aperture. The opening and closing operations are performed. In that case,
The relationship between the diaphragm blade and the drive ring may be such that a pin provided on the drive ring is fitted into an elongated hole (cam groove) formed in the diaphragm blade.

[0003]

As described above, the blade drive mechanism that causes the drive ring that reciprocally rotates about the optical axis to simultaneously rotate a plurality of blades in the same direction as in the case of the diaphragm blade drive mechanism. Even if there is a drive mechanism for the shutter blades, it is said that the higher the number of blades, the better as long as it has high performance and the other conditions do not change. Therefore, in consideration of various conditions, it is usually considered appropriate that the number of shutter blades is 5 and the number of diaphragm blades is 5 to 7. In the case of such a blade drive mechanism, all the constituent members must be manufactured with high precision, but in particular, in order to connect the drive ring and the blade, a long hole (cam groove) formed in one of them is used. ) Must be manufactured accurately and function properly.

Therefore, this will be described in the case of the diaphragm blade driving mechanism described in the above publication. This conventional example is provided with six diaphragm blades so that the minimum diaphragm aperture can be controlled to be extremely small. This means that a large number of control steps of the aperture diameter can be obtained. And, in order to obtain many different aperture sizes accurately, it is necessary to increase the rotation angle of the drive ring, but in order to do so, as long as such a conventional mechanism is adopted, the long hole (Cam groove) needs to be formed long. Therefore, it is completely impossible to form the long hole on the diaphragm blade side. Further, as can be seen from the drawings of this conventional example, if the elongated holes formed in the drive ring are made longer, the adjacent elongated holes come closer to each other. Therefore, it becomes necessary to improve the strength of the drive ring, which makes the manufacturing process troublesome and increases the cost. Further, it is impossible to increase the number of diaphragm blades as long as the long holes having the same shape are formed.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a drive ring that reciprocally rotates about an optical axis with a plurality of blades simultaneously. In the camera blade drive mechanism that is rotated in the direction, in order to connect the drive ring and the blade, it is not necessary to elongate the elongated hole formed in one of them.
It is an object of the present invention to provide a blade drive mechanism for a camera in which those blades can be opened and closed with suitable accuracy.

[0006]

In order to achieve the above object, a camera blade drive mechanism according to the present invention includes a first drive ring rotatable about an optical axis and a rotation about the optical axis. A plurality of possible second drive rings, each of which is rotatably connected to the first drive ring by a pin and circular hole fit and is connected to the second drive ring by a pin and long hole fit. The blade is provided with drive means for simultaneously rotating the first drive ring and the second drive ring at different rotation ratios. In that case, the first drive ring has a plurality of the circular holes, the second drive ring has a plurality of the elongated holes, and the plurality of blades are provided on one surface. Pins are individually fitted in the circular holes, and pins provided on the other surface are individually fitted in the elongated holes, and the rotation ratio of the first drive ring is the second drive ring. It is desirable to configure it to be larger.

Further, in the camera blade drive mechanism of the present invention, the first drive ring and the second drive ring each have a tooth portion, and the drive means controls the tooth portion with respect to these tooth portions. Having two gears that mesh separately provides a suitable transmission arrangement. In that case, if the two gears are configured as one concentric two-stage gear, it is also advantageous in terms of cost. Further, the driving means includes a motor, and the two gears and the third gear are configured as one concentric three-stage gear, and the third gear serves as an output gear of the motor. If the first drive ring and the second drive ring are rotated in conjunction with the motor by, for example, configuring them to be directly or indirectly connected,
This is extremely preferable as an electric blade mechanism.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to two examples configured as a driving mechanism for diaphragm blades. 1 and 2 show the first embodiment, FIG. 1 is a plan view showing a control state of the maximum aperture diameter, and FIG. 2 is a plan view showing a control state of the minimum aperture diameter. It is a figure. Further, FIG. 3 is a cross-sectional view of an essential part showing the second embodiment, and most of the structure of the first embodiment is applied to the structure other than the essential part. Therefore, in FIG. 3, the same members and portions as those in the first embodiment are designated by the same reference numerals.

First, the first embodiment will be described. As shown in FIGS. 1 and 2, the first drive ring 1 and the second drive ring 2 are arranged so as to surround the exposure opening 3 and are individually rotatable around the optical axis. Has become. Further, the first drive ring 1 has five circular holes 1a formed at evenly spaced positions, and the second drive ring 2 has five elongated holes 2a formed at equally spaced positions. Since the second drive ring 2 is shown with a part cut away for the sake of easy understanding of the drawing, the long hole 2a formed in the omitted part is shown by a chain double-dashed line. Further, the external shape of the omitted portion of the second drive ring 2 is the same as that of the first drive ring 1.
Is almost the same as.

Between the first drive ring 1 and the second drive ring 2, five diaphragm blades 4 of the same shape are arranged,
Each blade 4 has a pin 4a provided on one surface thereof as a first pin.
The pin 4b provided on the other surface is rotatably fitted into the circular hole 1a of the drive ring 1, and the pin 4b provided on the other surface of the drive ring 1 is provided in the long hole 2a of the second drive ring 2.
Is fitted to. The two-stage gear 5 has a shaft portion 5a rotatably supported by an appropriate member (not shown).
The large diameter gear 5b is meshed with the tooth portion 1b of the first drive ring 1, and the small diameter gear 5c is meshed with the tooth portion 2b of the second drive ring 2.

FIG. 1 shows a state in which each aperture blade 4 is rotated clockwise about a pin 4a to fully open the exposure aperture 3. Therefore, this state is a control state of the maximum aperture diameter, and the pin 4b of the aperture blade 4 is at one end position of the elongated hole 2a. In the state of FIG. 1, when the two-step gear 5 is rotated clockwise, the first drive ring 1 and the second drive ring 2 are simultaneously rotated counterclockwise. At this time, when the first drive ring 1 and the second drive ring 2 are rotated at the same rotation speed, the five diaphragm blades 4 do not rotate around the pin 4a, and the maximum diaphragm aperture is controlled. It remains in a state.

However, in the case of this embodiment, the large diameter gear 5b is meshed with the tooth portion 1b of the first drive ring 1, and the small diameter gear 5c is meshed with the tooth portion 2b of the second drive ring 2. Therefore, the first drive ring 1 is the second drive ring 2
Rotate faster than. Therefore, in FIG. 1, the circular hole 1a of the first drive ring 1 approaches as if chasing the long hole 2a of the second drive ring 2.
The pin 4b is moved in the optical axis direction by the cam action of the long hole 2a while moving in the long hole 2a. As a result, the five diaphragm blades 4 rotate counterclockwise around the pin 4b, and the area of the exposure aperture is reduced.

Then, the minimum aperture size is controlled,
The state in which the rotation of the two-stage gear 5 is stopped and the drive rings 1 and 2 are stopped is shown in FIG. Therefore, in order to obtain a desired control of the aperture diameter, it is sufficient to stop the two-step gear 5 at a predetermined rotation position before the state shown in FIG. By the way, the tooth portion 1b in FIG. 1 and FIG.
As can be seen by comparing the positions of 2b, the drive rings 1 and 2 are rotated by a considerable angle from the state of FIG. 1 to the state of FIG. This means that many intermediate aperture sizes can be selected with high accuracy. On the other hand, the angle at which the pin 4b of each diaphragm blade 4 moves within the elongated hole 2a is small. That is, the long hole 2
The length of a is short. This means that the strength of the second drive ring 2 can be sufficiently secured, which is advantageous in manufacturing, and the number of diaphragm blades 4 can be slightly increased.

By the way, in the present embodiment, the two drive rings 1 and 2 are simultaneously rotated by one two-stage gear 5 because they are advantageous in manufacturing, but the two drive rings 1 and 2 are separately provided. Gears may be rotated simultaneously, in which case the centers of the gears may be the same or different. Further, those gears may be manually rotated, or may be rotated by a step motor or the like. When the motor is used as the drive source, the two-stage gear 5 may be rotated via another gear, or the two-stage gear 5 may be directly connected to the motor and configured as an output gear of the motor. Also, the two drive rings 1,
The 2 may be rotated by separate motors.

Furthermore, if the rotation angles of the two drive rings 1 and 2 may be smaller than those in the embodiment, the two drive rings 1 and 2 are not rotated by gears. It is also possible that a part of the above is expanded in the radial direction to form a through hole, and the respective cam disks are simultaneously rotated in them. Then, the one configured as described above can be adopted as a drive mechanism for the diaphragm blades, but is more suitable for the drive mechanism for the shutter blades than the configuration of the present embodiment. Further, as the drive mechanism of the shutter blade, it is advantageous that the two drive rings 1 and 2 are simultaneously rotated by the different motors in opposite directions to increase the opening / closing speed of the shutter blade.

Further, in the present embodiment, when the two drive rings 1 and 2 are rotated by different motors, the following structure can be adopted. That is, the two-stage gear 5 rotated by the first motor is the first gear 5b having a large diameter.
It is used as a transmission gear from the motor, but is not used for rotating the first drive ring 1. If a part of the large-diameter gear 5b is always rotated between the two drive rings 1 and 2, the large-diameter gear 5b is a spacer between the two drive rings 1 and 2. Will also play the role of. On the other hand, another two-stage gear that is rotated by the second motor is connected to the two-stage gear 5 with the exposure opening 3 in between.
The first drive ring 1 is rotated by a small-diameter gear, and a part of the large-diameter gear is rotated between the two drive rings 1, 2. Therefore, in the case of such a configuration, if the tooth pitch and the number of teeth are the same, the diameter of the small diameter gear is the large diameter gear 5 of the two-step gear 5.
Since they have the same diameter as b, they cannot be used as common parts, but they are suitable configurations for smoothly rotating the two drive rings 1, 2.

Next, a second embodiment will be described with reference to FIG. FIG. 3 is a cross-sectional view showing only the main part of this embodiment, but the first drive ring 1, the second drive ring 2, the diaphragm blade 4 are shown.
The configuration of is the same as that of the first embodiment. The difference from the case of the first embodiment is that a three-stage gear 6 is used instead of the two-stage gear 5 and is rotated by a motor 7. That is, in the three-stage gear 6 that rotates around the shaft portion 6 a, the medium diameter gear 6 b is the tooth portion 1 b of the first drive ring 1.
The small-diameter gear 6c is meshed with the tooth portion 2b of the second drive ring 2. Further, a large-diameter gear 6d between a medium-diameter gear 6b and a small-diameter gear 6c is meshed with an output gear 8 attached to the rotary shaft of a motor 7. The medium diameter gear 6b and the small diameter gear 6c correspond to the large diameter gear 5b and the small diameter gear 5c in the first embodiment.

Although this embodiment has such a configuration, the control of the aperture diameter is performed by rotating the first drive ring 1 and the second drive ring 2 at different speeds as compared with the case of the first embodiment. It is done in exactly the same way. Therefore, detailed description thereof will be omitted. The structural feature of this embodiment is that the large-diameter gear 6d serves as a spacer for keeping the first drive ring 1 and the second drive ring 2 at a predetermined distance. As a result, not only the first drive ring 1 and the second drive ring 2, but also the diaphragm blades 4 can operate smoothly. However, it is impossible to properly maintain the distance between the first drive ring 1 and the second drive ring 2 only with the large-diameter gear 6d. It goes without saying that one or more must be provided.

Further, although the three-stage gear 6 is directly connected to the output gear 8 in the present embodiment, it may be connected via another gear. Further, the three-stage gear 6 of this embodiment may be directly attached to the rotary shaft of the motor 7, but in that case, there is no point in providing the large-diameter gear 6d, so that portion is used as a flange. It is preferably formed. As described in the first embodiment, in the case of the present invention, the length of the long hole 2a is shorter than that of the conventional one. Therefore, a long hole corresponding to the long hole 2a is formed in the diaphragm blade 4, It is also possible to provide a pin corresponding to 4b on the second drive ring 2. Further, in the case of each of the above embodiments, the circular hole 1a is formed in the first drive ring 1,
Although the pin 4b to be fitted therein is provided on the diaphragm blade 4, it is also possible to form a circular hole corresponding to the circular hole 1a on the diaphragm blade 4 and provide a pin corresponding to the pin 4b on the first drive ring 1. Absent.

[0020]

As described above, according to the present invention, a plurality of blades are attached to two drive rings, and the drive rings are simultaneously reciprocally rotated in the same direction about the optical axis at different rotation ratios. Therefore, in order to connect the one drive ring and the blade, the long hole formed in one of the drive rings does not have to be long for the rotation angle of the drive ring described above. When adopted as a mechanism, it is easy to increase the number of blades, and it is possible to select a multi-stage aperture diameter with suitable accuracy even if the long hole is short.

[Brief description of drawings]

FIG. 1 is a plan view showing a control state of a maximum aperture diameter in a first embodiment.

FIG. 2 is a plan view showing a control state of a minimum aperture diameter in the first embodiment.

FIG. 3 is a cross-sectional view of essential parts of a second embodiment.

[Explanation of symbols]

1st drive ring 1a circular hole 1b, 2b teeth 2 Second drive ring 2a long hole 3 exposure aperture 4 diaphragm blades 4a, 4b pins 5 two-stage gear 5a, 6a Shaft 5b, 5c, 6b, 6c, 6d gears 6 3-step gear 7 motor 8 output gears

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03B 9/24 G03B 9/24

Claims (6)

[Claims] 1. A first drive ring rotatable about an optical axis, a second drive ring rotatable about the optical axis, and a first drive ring each having a pin and a circular hole fitted therein. A plurality of blades that are rotatably connected to each other and are connected to the second drive ring by fitting pins and elongated holes;
A blade drive mechanism for a camera, comprising: a drive unit that simultaneously rotates the drive ring and the second drive ring at different rotation ratios. 2. The first drive ring has a plurality of the circular holes, the second drive ring has a plurality of the elongated holes, and the plurality of blades are provided on one surface. The provided pins are individually fitted into the circular holes, and the pins provided on the other surface are individually fitted into the elongated holes, and the rotation ratio of the first drive ring is the second one. The blade drive mechanism for a camera according to claim 1, wherein the blade drive mechanism is larger than the drive ring. 3. The first drive ring and the second drive ring each have teeth, and the drive means includes two gears that mesh with the teeth separately. The blade drive mechanism for a camera according to claim 1 or 2, wherein. 4. The camera blade drive mechanism according to claim 3, wherein the two gears are configured as one concentric two-stage gear. 5. The driving means includes a motor,
The two gears and the third gear are configured as one concentric three-stage gear, and the third gear is directly or indirectly connected to the output gear of the motor. The blade drive mechanism for a camera according to claim 3. 6. The driving means includes a motor,
The blade drive mechanism for a camera according to claim 1, wherein the first drive ring and the second drive ring are rotated by using the motor as a drive source.