JPH0714443U - Driving device for camera shutter - Google Patents

Abstract

(57) [Abstract] [Purpose] The drive pin that reciprocally rotates integrally with the permanent magnet rotor of the moving magnet type motor opens and closes the shutter blades, and when the shutter blades are in the closed position and the open position, when no power is supplied. In a camera shutter drive device in which the shutter blades are biased to a stable state by a magnetic action, the number of components is reduced and the size is reduced as compared with the conventional drive device. [Structure] Drive pin 5 that is integrally formed with rotor 5
c causes the shutter blades to open and close by the reciprocating operation. The two small pieces of yokes 12 and 13 have an arc shape so as to face the peripheral surface of the rotor 5, and are inserted into a recessed portion provided in the upper coil frame 6 along the rotary shaft 5b.
The length of the arc is matched with the operating angle range of the drive pin 5c.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a drive device using a so-called moving magnet type motor in a camera shutter in which a drive pin that reciprocates integrally with a rotor opens and closes a shutter blade.

[0002]

[Prior art]

 Conventionally, in a drive device using a moving magnet type motor, the motor is de-energized when the camera is not used, and therefore the shutter blades in the closed position are placed in an extremely unstable state. Therefore, there is a concern that the shutter blade may unexpectedly operate due to the influence of vibration and the like, causing light leakage. Various proposals have been made in the past to eliminate such a point, but an example using a magnetic means without using a mechanical means such as a spring force or a locking mechanism is shown in FIG. This will be described with reference to FIG. In FIG. 5, an opening 1a and an outer wall 1b are formed in the main plate 1, and shafts 1c and 1d are planted. The cover plate 2 is fixed to the base plate 1 via an outer wall 1b, a space for accommodating the shutter blades is formed between the cover plate 2 and the base plate 1, and the cover plate 2 has an opening 2a for forming an exposure opening together with the opening 1a. There is. The shutter blades 3 and 4 are pivotally supported by shafts 1c and 1d between the base plate 1 and the cover plate 2. The moving magnet type motor M is fixed to the front side of the main plate 1, and a drive pin 5c described later is fitted into the slots 3a, 4a of the shutter blades 3, 4 through a window (not shown) formed in the main plate 1. I am fit. A moving magnet type motor M whose schematic shape is shown by a chain double-dashed line in FIG. 5 is shown in detail in FIGS. 6 and 7. FIG. 7 is a cross-sectional view of FIG. The rotor 5 is composed of a permanent magnet 5a, a rotary shaft 5b and the drive pin 5c described above. A coil frame is constituted by the upper coil frame 6 and the lower coil frame 7, and the upper coil frame 6 is fitted in an arcuate groove portion 7 a formed in the lower coil frame 7. Further, the lower coil frame 7 has mounting holes 7b and 7c for attaching to the ground plate 1, and forms a window 7d over the operating angle range of the drive pin 5c. The coil 8 is wound around the coil frames 6 and 7 so as to cover the bearing portion of the rotating shaft 5b. The rod-shaped magnetic bodies 9 and 10 are inserted into the holes provided in the upper coil frame 6 from above in FIG. 7, and the yoke 11 is attached so as to face and surround the peripheral surface of the rotor 5. .

In the motor having the above structure, the rotor 5 rotates in one direction when a current is applied to the coil 8 in one direction, and the rotor 5 rotates in the opposite direction when a current is applied in the opposite direction. . Reference numeral A in FIG. 5 indicates the position of the rotary shaft 5b shown in FIGS. 6 and 7. Therefore, as can be seen from the positional relationship between the rotary shaft 5b and the drive pin 5c, when the shutter blades 3 and 4 are in the open position shown in FIG. 5, the rotor 5 in FIG. In the closed position of the shutter blades 3 and 4, on the contrary, the shutter blades 3 and 4 are rotated by about 30 degrees in the clockwise direction. When the shutter blades 3 and 4 are in the closed position, the permanent magnet 5a in FIG. 6 has a boundary portion between the N pole and the S pole facing the magnetic body 10 and the magnetic body 9 has the center of the N pole. The parts are facing each other. Therefore, the rotor 5 is securely held by the maximum magnetic force acting between the magnetic body 9 and the N pole, and the shutter blades 3 and 4 are maintained in the closed position by the drive pin 5c. When the shutter blades 3 and 4 are in the open position, the position of the boundary between the N pole and the S pole faces the magnetic body 9, and the magnetic body 10 faces the central portion of the S pole. Therefore, the rotor 5 is securely held, and the shutter blades 3 and 4 maintain the open position. In this way, the shutter blades 3 and 4 are securely held in the closed position to prevent accidental light leakage when the camera is not used, and the shutter blades 3 and 4 can be reliably held in the open position. Bounds at the open position can be suppressed by holding the coil at the open position, and when performing bulb photography, the fully open position can be maintained while the coil 8 is de-energized.

[0004]

[Problems to be solved by the device]

 As can be seen from FIG. 5, the motor having the above structure is made quite small. However, in reality, many shutter-related parts are attached to the main plate 1, and many parts such as lens-related parts are arranged in this space due to the camera design. Therefore, the motor can be made smaller than ever. This is the most important issue in this type of shutter.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a drive pin which is integrally formed with a rotor of a permanent magnet and which moves forward and backward together with the rotor. A shutter drive for a camera, which operates to open and close the shutter blades and maintain a stable state by magnetic action at the closed position and the open position when de-energized. The object is to provide a drive device with less and smaller size.

[0006]

[Means and Actions for Solving the Problems]

 In order to achieve the above object, a driving device for a camera shutter according to the present invention comprises a rotor made of a permanent magnet and a shutter integrally reciprocally rotated at a position between magnetic poles of the rotor. A drive pin that opens and closes the blades, a coil frame that rotatably supports the rotor and winds a coil so as to cover the bearing portion of the rotor, and a yoke that is disposed at a position facing the peripheral surface of the rotor. The yoke is arranged over a predetermined angle within the operating angle range of the drive pin and at least one of the angular ranges symmetrical with respect to the rotor with respect to the operating angle range.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment A first embodiment of the present invention will be described with reference to FIGS. 1 is a plan view, and FIG. 2 is a cross-sectional view of FIG. 1, which respectively correspond to FIGS. 6 and 7 showing the above-mentioned conventional example. I am using. Therefore, the configuration of this embodiment is different from the conventional example in that two small piece yokes 12 and 13 are used instead of the annular yoke 11 in FIG. 6 and the rod-shaped magnetic bodies 9 and 10 in the conventional example are used. Is the loss. Each of these yokes 12 and 13 has an arcuate shape so as to face the circumferential surface of the rotor 5 at the same distance in FIG. 1, and is formed in a recessed portion of the same shape provided in the upper coil frame 6. It is fitted. The lengths of the arcs are matched to the operating angle range of the drive pin 5c.

In this embodiment, like the conventional example, the drive pin 5c is at a position rotated by about 30 degrees clockwise from the state of FIG. 1 at the shutter blade closed position. At this time, one of the positions of the boundary between the S pole and the N pole of the electromagnet 5a is at the upper end of the yoke 12, and the other is opposed to the lower end of the yoke 13. Therefore, when the coil 8 is not energized, in relation to the yoke 12, the rotor 5 is rotated in the clockwise direction, that is, the shutter blade closing direction by the magnetic force acting between the S pole and the yoke 12. In addition, in the relationship with the yoke 13, the rotational force is also given in the clockwise direction by the magnetic force acting between the N pole and the yoke 13. On the other hand, in the open position of the shutter blade, the drive pin 5c is at a position rotated about 30 degrees counterclockwise from the state of FIG. Therefore, in this case, the relationship is the reverse of that described above, and even when the coil 8 is not energized, the attraction force is generated between the yoke 12 and the N pole, and between the yoke 13 and the S pole. It is working, and the rotating force is further applied to the rotor 5 in the counterclockwise direction, that is, the opening direction of the shutter blades. In this way, the shutter blades are securely held in both the closed position and the open position.

As can be seen from the above description, in this embodiment, in principle, either one of the yokes 12 and 13 may be omitted, and the arc shape in FIG. 1 has the driving pin 5c. As long as it is within the working angle range, the size of the smaller angle range may be used. Furthermore, if the arc shape of the yokes 12 and 13 is small, it may extend to a length exceeding the above working angle range. Although it does not matter, the embodiment of FIG. 1 can be said to be an ideal form in view of the original meaning of providing the yoke and also in view of the holding force of the shutter blade described above.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIGS. 3 and 4. Similar to the case of the first embodiment, FIG. 3 is a plan view of the second embodiment, and FIG. 4 is a transverse sectional view of FIG. The numbering method is the same as in the first embodiment. The point that is substantially different from the case of the first embodiment is the shape of the yoke. The yoke 14 in this embodiment has side surface portions 14a, 14b, and a top portion 14c, mounting holes 14d, 14e for the main plate 1 are formed in the edge portion, and the side surface portions facing each other are cut off as a top hat shape. Are doing As shown in FIG. 3, the side surface portions 14a and 14b have an arc-shaped cross section, and the length of the arc is adjusted to the operating angle range of the drive pin 5c. The magnetic action effects at the closed position and the open position of the shutter blades are the same in the case of the first embodiment as well, so the description thereof is omitted. Further, it is the same that the vertical dimension of the yoke 14 in FIG. 3 can be set small within the operating angle range of the drive pin 5c. Further, the shape of the yoke 14 may be a cup shape with the opposite side surfaces cut off, and this may be fixed to the upper coil 6.

[0011]

[Effect of device]

 As described above, as is clear from the comparison between the configuration of the embodiment shown in FIGS. 1 and 3 and the configuration of the conventional example shown in FIG. , 10 are not required, the number of parts is reduced, and the vertical dimension in each figure is reduced by twice the thickness of the yoke. This makes it possible to make the outer diameter of the base plate 1 smaller, as can be understood from the arrangement relationship in FIG. 5, and there is a large degree of freedom in the size and arrangement of the other components installed on the base plate 1. Has the advantage that

[Brief description of drawings]

FIG. 1 is a plan view of a first embodiment of the present invention.

2 is a cross-sectional view of FIG.

FIG. 3 is a plan view of a second embodiment of the present invention.

4 is a cross-sectional view of FIG.

FIG. 5 is a plan view showing a state in which a conventional product is attached to a bottom plate of a shutter.

FIG. 6 is a plan view of a conventional product.

7 is a cross-sectional view of FIG.

[Explanation of symbols]

 1 Main plate 1a, 2a Opening 1b Outer wall 1c, 1d Axis 2 Cover plate 3,4 Shutter blade 3a, 4a Slot M Moving magnet type motor 5 Rotor 5a Permanent magnet 5b Rotating shaft 5c Drive pin 6 Upper coil frame 7 Lower coil frame 7a Groove 7b, 7c, 14d, 14e Mounting hole 7d Window 8 Coil 9,10 Magnetic material 11, 12, 13, 14 Yoke 14a, 14b Side surface 14c Top

Claims (4)

[Scope of utility model registration request] 1. A rotor composed of a permanent magnet, a drive pin which is integrally formed at a position between magnetic poles of the rotor and which reciprocally rotates to open and close a shutter blade, and rotatably supports the rotor. The coil frame has a coil wound so as to cover the bearing portion, and a yoke arranged at a position facing the peripheral surface portion of the rotor. The yoke has an operating angle range of the drive pin and the yoke. A driving device for a camera shutter, wherein the driving device for a camera shutter is arranged over a predetermined angle in at least one of the angular ranges that are symmetrical with respect to the rotor. 2. The drive device for a camera shutter according to claim 1, wherein a part of the yoke is arranged beyond the predetermined angle. 3. The camera shutter according to claim 1, wherein the yoke is a small piece having an arc shape in a rotation plane of the rotor and is fitted in the coil frame. Drive. 4. The drive device for a camera shutter according to claim 1, wherein the yoke has a substantially cup-like shape with side surfaces facing each other cut off.