JPH0446328A - Light quantity stopping device - Google Patents

Abstract

PURPOSE:To abolish a bearing cap which is heretofore used as a bearing by using the front and rear surfaces of a base plate as the functions of the bearings for a revolving shaft. CONSTITUTION:Symbols 10, 11 are coils for detecting driving and speed and 13 is a yoke constituting a closed magnetic circuit. The 1st bearing is constituted of a part 5a of a driving lever 5 and a bearing part 6b of the base plate 6 and acts as a carrier in the downward direction of Fig. The 2nd bearing is constituted of a step part 8a of a revolving shaft 8 and a bearing part 6 of the base plate 6 and acts as a carrier in the upward direction of Fig. Namely, the part 5a of the driving lever S and the step 8a of the shaft 8 are formed to the diameter larger than the diameter of a shaft hole 6d, by which the functions as the bearings are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a light amount diaphragm device used in video cameras, still cameras, and the like.

[Prior Art] A conventional light amount diaphragm device is shown in FIG. The rotary shaft 8' of the driving section has a step formed on the top and bottom, and the upper part is received by the throttle base plate 6', and the lower part is received by the bearing cap 30. FIG. 8 also shows another conventional example, and the difference from FIG. 4 is that the lever 4 is used to bias the drive lever 5' for moving the aperture blades 2.3 in the direction of closing the aperture. The only difference is the arrangement, and the one-rotation shaft 8' is supported by the throttle base plate 6' and the bearing cap 30.

[Problems to be Solved by the Invention] However, in the conventional example described above, the distance between the bearings is long, and the distance between the bearings is constructed of other members, so there are the following problems. In other words, since the distance between the bearings is long and the number of parts that make up the bearing is large, the bearing-to-bearing straightness is poor and the load is large.

[Means for Solving the Problems] According to the present invention, the rotating shaft of the drive section is supported by the base plate and the drive lever, thereby shortening the distance between the bearings, improving straightness, and reducing cost. To provide a light amount diaphragm device that can be downsized.

[Example] Figures 1 to 3 are drawings that best express the features of the present invention.
Reference numerals 2 and 3 denote aperture blades having openings for adjusting the amount of light, and are slidably supported on the base plate 6.

Reference numeral 4 denotes a spring incorporated in the drive lever 5 in order to close the aperture with the aperture blades 2 and 3 when electricity is stopped. 5 uses the driving force generated by the coil and magnet to drive the aperture blade 2 through pin 5C.
．． 3 is a drive lever for driving the aperture blades, 6 is a support part 6a of the aperture blades, and a bearing part 6.
b, 6c and a base plate having a shaft hole 6d, 7 is a magnet,
8 is a rotating shaft connected to the magnet 7 and the drive transmission lever 5. 9 is a bobbin around which coils 10 and 11 are wound. 1
0.11 is a coil for detecting drive and speed. 13
There is a yaw that forms a closed magnetic circuit. A portion 5a of the drive lever 5 and a bearing portion 6b of the base plate 6 constitute a first bearing,
It is placed downward in the figure. Conventionally, this mechanism consisted of a shaft and a bearing cap. Also, the stepped portion 8a of the rotating shaft 8
The bearing portion 6c of the base plate 6 constitutes a second bearing, which is the bearing in the upper direction in the figure. That is, part 5 of the drive lever S
A and the step 8a of the shaft 8 are made larger in diameter than the shaft hole 6d, so that they function as a bearing.

FIG. 881 shows an embodiment in which the spring storage portion is located on the aperture base plate 6 side, and FIG. 2 shows an embodiment in which the spring storage portion is located on the l side of the support member of the aperture blades 2 and 3.

In the embodiment described above, the two upper and lower bearings can be constructed from one part of the base plate 6, so it can be made using a mold, etc., and the bearing can have good straightness and reduce the load caused by shaft friction. Furthermore, since a bearing cap is not required, a supporting and fixing mechanism for the bearing cap is also not required, the number of parts is reduced, and assembly work is simplified, resulting in cost reduction effects, weight reduction, and miniaturization.

[Other Embodiments] FIGS. 5 and 6 show embodiments of a surface facing type light amount diaphragm device using the present invention. Reference numeral 11 denotes a support member that presses down the aperture blades, and reference numerals 12 and 13 denote aperture blades having openings for adjusting the amount of light.

Reference numeral 14 denotes a spring incorporated in the drive lever 15 in order to close the opening with the aperture blades 12, 13 when the power supply is stopped. 15 is a drive lever that transmits the driving force generated by the coil 20.21 and the magnet 17 to the aperture blade 12.13.
6 is a base plate that accommodates the aperture blade support portion 15a and bearing portions 16b and 16c. 17 is a magnet, 18 is a rotating shaft, 20 is a drive coil, 21 is a braking coil, 23 is a rotor yoke forming a closed magnetic circuit, and 28 is a fixed yoke similar to the rotor yoke 23.

FIG. 5 is a sectional view. FIG. 6 is a plan view of the drive section. The broken line in Figure 6 indicates the magnet 17. magnet 1
7 is multipolarized as shown in the figure. In the case of Fig. 6, there are four poles.

A plurality of coils 20, 21 are arranged with respect to the magnet 17 as shown in the figure. The number of coils may be at least one for driving and one for braking. In the case of FIG. 6, four are arranged. In this case, it is divided equally into two parts for the drive and two parts for the brake, but it is not necessary to divide them equally, and it may be 34 Wi for the drive and one for the brake. The driving principle is the same as in the conventional example, and the driving force is generated by a coil and a magnet, the rotating shaft 18 rotates, and the driving lever 15 connected to the rotating shaft I8 also rotates. The aperture blades connected to the drive lever 18]1.12 are moved to change the amount of light.

The bearing structure is similar to the embodiment described above, in which the bearing portions 16b and 16c on the front and back surfaces of the aperture base plate 16 are connected to the stepped portion 18 of the rotating shaft 18.
a and the drive lever 15 are directly received.

In this embodiment, it is possible to make the driving part very small in the height direction (statement 3). In addition, an air-core coil that does not require a bobbin or the like is used, and the structure is simple, resulting in a significant cost reduction effect. Incidentally, since such a surface facing type light quantity diaphragm device does not have a coil bobbin, it is difficult to attach a bearing cap used for a conventional bearing, and the above embodiment is highly effective from this point as well.

[Effects of the Invention] Since the front and back surfaces of the base plate are used as bearings for the rotating shaft, the bearing caps conventionally used as bearings can be eliminated, and the distance between the bearings can also be shortened. This greatly improves straightness, reduces shaft loss, and further reduces cost and size by reducing the number of parts.

[Brief explanation of the drawing]

FIG. 1 is an enlarged cross-sectional view of a light aperture device as an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of a light aperture device as another embodiment. FIG. TS4 is a sectional view of the drive section of a conventional light aperture device. FIG. 5 is a sectional view of the drive section of a light aperture device of another embodiment. FIG. 6 is a plan view of FIG. 5. Fig. 2 is a block diagram of a light aperture device. Fig. 8 is a block diagram of another conventional light aperture device. 2.3, 12.13...
Aperture blade 5.15... Drive lever 6.16... Aperture base plate 18... Rotation shaft

Claims (1)

[Claims] (1) In a light aperture device that has a drive lever attached to a rotating shaft that is driven by magnetic action, and that moves aperture blades to adjust the amount of light by rotating the drive lever, the rotating shaft has a diameter. A step is formed by the difference, and the step is placed close to the base plate on one side across the base plate, and the drive lever is placed close to the base plate on the other side, so that the base plate can be used as a bearing. A light amount diaphragm device characterized by having functions.