JP4191556B2 - Camera aperture device - Google Patents

Description

  In the present invention, the aperture ring that reciprocally rotates about the optical axis can change the size of the aperture opening while keeping the shape of the aperture opening substantially circular by simultaneously rotating a plurality of aperture blades in the same direction. The present invention relates to an aperture device for a camera.

In the camera aperture device, a plurality of aperture blades are mounted at substantially equal intervals around the opening for exposure, and when the aperture ring rotates about the optical axis, the rotation direction corresponds to the rotation direction. In some cases, the diaphragm blades are simultaneously rotated in the same direction to change the size of the aperture. In addition, as a means for driving the diaphragm ring, there are a case of only manual operation, a case of using manual and spring force, a case of using spring force and motor, and a case of only motor, but recently, only a motor is used. There are many cases of driving. When a motor is used as the driving means, a narrowing portion is formed on the aperture ring in order to speed up the operation of the aperture ring so as not to miss the shutter chance and to reduce power consumption. Is also known (see, for example, Patent Document 1).
JP 2002-90796 A (page 3-6, FIG. 1-7)

  By the way, the conventional diaphragm ring has been manufactured by punching a metal plate with a press machine so that the diaphragm blade cannot be smoothly rotated due to deformation due to secular change or deformation during operation. For this reason, there is a problem in that the price of the plate material itself is high, and secondary processing such as rust prevention treatment must be performed after punching, resulting in an increase in unit cost. Furthermore, when the aperture ring is made of metal, when the driving means is a motor, a loud noise is generated from the meshing portion of the tooth portion formed on the aperture ring and the gear rotated by the motor, In particular, when employed in a video camera, the sound is recorded as noise, which is one of the major limitations in designing the camera.

  The present invention has been made to solve such problems, and the object of the present invention is to reduce the cost and weight as compared with the conventional aperture ring and to rotate it quickly even with a small force. It is possible to provide an aperture device for a camera that includes an aperture ring that consumes less power and can be made quieter when driven by a motor.

In order to achieve the above-mentioned object, the diaphragm device for a camera of the present invention includes a base plate having a circular exposure opening centered on the optical axis, and each having an engaging pin, A plurality of diaphragm blades rotatably attached to the base plate around the opening for rotation and rotated between a maximum opening control position and a minimum opening control position by operating the engagement pin; , Which is arranged to rotate around the optical axis around the opening for exposure, and is formed between a plurality of cam grooves and the adjacent cam grooves for operating the engagement pin by the rotation. a plurality of lightening portions have that synthetic resin squeeze ring has been, comprise a driving means for reciprocally rotating the aperture ring on at least one surface of the diaphragm ring, the cam groove Ribs are integrally molded along the edges So as to have.

In that case , the diaphragm ring is roughened by integral molding on the inner diameter surface and at least a part of the surface that is opposite to the ground plane and close to the photographing optical path. By doing so, the reflected light from the aperture ring does not affect the photographing light without increasing the cost, and a suitable image can be obtained. In addition, when the aperture ring is driven by a motor, it can be driven smoothly with less power consumption, and the sound generated from the gear mechanism can be made extremely small.

  As described above, according to the diaphragm device for a camera of the present invention, the diaphragm ring is made of synthetic resin, so that the cost and weight can be reduced as compared with the conventional metal diaphragm ring. When a (polyethylene terephthalate) plate material is punched with a press machine, the effect is even greater. In addition, because the aperture ring is lighter, it can be rotated quickly even with a small force, and when driven by a motor, it consumes less power than before and can be made quieter. effective.

  Embodiments of the present invention will be described with reference to four illustrated examples. 1 is a plan view of the first embodiment showing the control state of the maximum aperture, FIG. 2 is a cross-sectional view of FIG. 1, and FIG. 3 is the first embodiment showing the control state of the minimum aperture. FIG. FIG. 4 is a cross-sectional view for explaining the second embodiment. 5 is a plan view of the third embodiment showing the control state of the maximum aperture opening, FIG. 6 is a sectional view of FIG. 5, and FIG. 7 is an implementation showing the control state of the maximum aperture opening. FIG. 8 is a plan view of Example 4, and FIG. 8 is a cross-sectional view of FIG. 1, 3, 5, and 7 described above can be viewed from the object side or the image plane side when incorporated in the camera. In the description of the example, it is assumed that the drawing is viewed from the subject side. Therefore, in the case of FIGS. 2, 4, 6, and 8, the upper side is the subject side.

  First, the configuration of the first embodiment will be described. The base plate 1 and the cover plate 2 are made of synthetic resin, and are attached to each other by means not shown, and circular openings 1a and 2a centering on the optical axis are formed at their substantially central portions. Although formed, a part of the cover plate 2 is cut and shown in FIG. The two openings 1a and 2a are smaller in diameter than the opening 1a, and regulate the opening for the photographing optical path (that is, the maximum aperture opening).

The diaphragm ring 3 of the present embodiment is made of synthetic resin and is manufactured by injection molding, and has seven cam grooves 3a formed at substantially equal angular intervals, and the tooth portion 3b has a predetermined angular range on the outer periphery. Is formed. Further, the diaphragm ring 3 is slightly thicker than the conventional metal diaphragm ring, so that the light from the subject is reflected on the inner diameter surface and the vicinity thereof, and flare or the like is formed on the periphery of the image after photographing. There is a possibility of generating. Therefore, in the case of the present embodiment, the inner diameter edge is formed into a chamfered shape, and the inner diameter surface and the surface opposite to the base plate 1 are roughened by a mold (arrow A in FIG. 2). ). The diaphragm ring 3 is configured such that the surface on the ground plate 1 side is not in close contact with the ground plate 1 by means (not shown) provided on the ground plate 1 and the outer peripheral surface is pressed by the cover plate 2. In the hollow formed in the main plate 1, it is rotatable.

  Between the main plate 1 and the diaphragm ring 3, seven diaphragm blades 4 are arranged at substantially equal angular intervals with the optical axis as the center. All of the diaphragm blades 4 have the same shape, and a shaft pin 4a provided on the base plate 1 side is rotatably fitted in a hole formed in the base plate 1 so as to cover the cover plate 2 side. The engaging pin 4 b provided on the cam ring 3 is inserted into the cam groove 3 a formed in the aperture ring 3.

  Next, the configuration of the step motor 5 will be described. FIG. 2 shows the configuration in a developed state for easy understanding of the configuration. Further, the step motor 5 of the present embodiment has substantially the same configuration as the step motor described in Patent Document 1, and all the constituent members are attached to the first mounting plate 5a and the second mounting plate 5b. ing. The first attachment plate 5a and the second attachment plate 5b are attached to each other by means not shown, and the first attachment plate 5a is attached to the ground plate 1 by means not shown.

  The rotor 5c includes a shaft portion made of synthetic resin, a cylindrical permanent magnet attached to the shaft portion, and an output gear formed integrally with the shaft portion, and is attached to the first mounting plate 5a. The shaft 5d is erected so as to be rotatable. The permanent magnet is magnetized in four poles in the radial direction. The stator is composed of two yokes 5e and 5f attached to the first attachment plate 5a by means not shown, and coils 5g and 5h wound around one leg of each. The yokes 5e and 5f have magnetic poles at the tips of their two legs, which are inserted into holes formed in the base plate 1 so as to face the circumferential surface of the permanent magnet of the rotor 5c. ing. Further, the reduction gear 5i is a synthetic resin two-stage gear (parent-child gear) composed of a parent gear and a child gear, and is rotatably attached to a shaft 5j provided on the first attachment plate 5a. The master gear is meshed with the output gear of the rotor 5 c, and the slave gear is meshed with the tooth portion 3 b of the aperture ring 3.

  Next, the operation of this embodiment will be described. FIG. 1 shows a state in which seven diaphragm blades 4 are at a position where the opening 1a is fully opened, that is, at the maximum diaphragm opening control position. In this state, when a pulse signal is applied to the coils 5g and 5h, the rotor 5c is rotated in the clockwise direction, and the rotation is transmitted from the output gear via the reduction gear 5i. 3 is also rotated clockwise. Therefore, the outer cam of each cam groove 3a (the cam edge that is far from the optical axis among the two cam edges formed in the longitudinal direction of the cam groove 3a) presses the engagement pin 4b, Rotate counterclockwise.

  Therefore, the seven diaphragm blades 4 enter the opening 1a and continuously reduce the diaphragm opening. When the diaphragm blade 4 reaches a predetermined opening control position, the pulse signals for the coils 5g and 5h are cut off, the rotation of the rotor 5c is stopped, and the rotation of the diaphragm blade 4 is also stopped. FIG. 3 shows a state in which the seven diaphragm blades 4 are stopped at the minimum diaphragm opening control position. Thus, when the rotation of the aperture blade 4 is stopped, exposure for photographing is performed immediately after that.

  When the exposure for photographing is completed, the rotor 5c is rotated in the opposite direction to the above, and the aperture ring 3 is rotated counterclockwise via the reduction gear 5i. Therefore, this time, the inner cam of each cam groove 3a (the cam edge closest to the optical axis as a whole among the two cam edges formed in the longitudinal direction of the cam groove 3a) presses the engagement pin 4b, The aperture blade 4 is rotated clockwise. Therefore, the seven diaphragm blades 4 continuously increase the diaphragm aperture, and immediately after the diaphragm aperture 4 is completely retracted from the opening 1a, the pulse signals to the coils 5g and 5h are cut off, and the state shown in FIG. Return.

  In the above description of the operation, the diaphragm device according to the present embodiment is described as an example of a still camera. However, when the diaphragm device is employed in a video camera, the diaphragm blades 4 are exposed to the brightness of the subject during shooting. Needless to say, it can be rotated clockwise or counterclockwise in response to the change of.

  As described above, the diaphragm ring 3 of the present embodiment is manufactured by injection molding of a synthetic resin material, and thus is clearly lower in terms of material cost than the conventional metal diaphragm ring. . In addition, unlike the conventional drawing ring, secondary processing such as rust prevention processing is not required after punching processing, and this is also low in cost. In addition, when the aperture ring 3 is made of synthetic resin, it may be necessary to apply antireflection processing to the region near the inner diameter. Even in this case, a portion corresponding to the region is required as in this embodiment. If a die roughened by sandblasting in advance is used, the region can be roughened and reflection can be prevented without substantially increasing the cost. In this case, it goes without saying that it is more effective to select a black material.

  Furthermore, since the aperture ring 3 of the present embodiment is made of synthetic resin, it is much lighter even if it is slightly thicker than the conventional aperture ring. Therefore, it is possible to quickly operate even with a small force, and when used in a still camera, the time until actual shooting is shortened and the chance of missing a photo opportunity is reduced. In addition, when driven by a motor as in the present embodiment, it becomes possible to reduce power consumption, and the diaphragm ring 3 of the present embodiment is made of synthetic resin, so that the conventional metal The noise generated between the tooth portion 3b and the reduction gear 5i can be made quieter than in the case of the aperture ring. Therefore, particularly when employed in a video camera, the responsiveness to changes in subject light is improved, and noise countermeasures are advantageous.

  Next, the second embodiment will be described with reference to FIG. 4. The major difference between the present embodiment and the first embodiment is that the manufacturing method of the aperture ring is different and the thickness is different. The shape is the same. Therefore, although the thickness of the aperture ring is different, in FIG. 4, the aperture ring of the present embodiment is also given the same reference numerals as in the first embodiment. The other members and parts are substantially the same as those in the first embodiment. For this reason, the same reference numerals as those in the first embodiment are assigned to them, and the description thereof is omitted. 1 and 3 can be applied to this embodiment as they are. Accordingly, the operation of the present embodiment is substantially the same as that of the first embodiment, and thus the description thereof is also omitted.

As described above, the diaphragm ring 3 of the first embodiment has been described on the assumption that the thickness thereof is slightly thicker than that of a conventional metal diaphragm ring. By the way, the conventional metal diaphragm ring is usually about 0.5 mm in thickness. It is not so easy to produce a drawing ring with such a thickness by injection molding. This is because the diaphragm ring is formed with a plurality of cam grooves, and the shape of the cam groove determines the stability and position accuracy of the operation of the diaphragm blades. Therefore, the diaphragm ring is deformed under various conditions. it Dzu leprosy is required, when aperture ring which is produced in an injection molding process, unless taken some means, it is difficult to a conventional aperture ring similar thickness.

  Therefore, the aperture ring 3 of this embodiment is not manufactured by injection molding, but is manufactured by punching a PET (polyethylene terephthalate) plate with a punching machine. A PET (polyethylene terephthalate) plate is much cheaper than a metal plate. Moreover, since the aperture ring 3 manufactured in this way does not require rust prevention, it can be manufactured at a lower cost than the conventional aperture ring. Furthermore, the diaphragm ring 3 of the present embodiment has a predetermined strength, but is thinner and lighter than the conventional diaphragm ring, so that the above-described antireflection processing is not necessary. Therefore, it is possible to operate quickly even with a small force, and when driven by a motor as in the present embodiment, it is possible to reduce power consumption and extremely reduce the sound generated from the gear mechanism. become.

  Next, the third embodiment will be described with reference to FIGS. 5 and 6. The difference between the present embodiment and the first embodiment is only that the shape of a part of the aperture ring is different. Therefore, in FIGS. 5 and 6, the same reference numerals as those of the first embodiment are also given to the aperture ring of the present embodiment. In addition, since each other member and site | part are substantially the same as the case of Example 1, the same code | symbol as Example 1 is also attached to them, and description is abbreviate | omitted. The operation of the present embodiment is substantially the same as that of the first embodiment. Therefore, the description of the operation is also omitted.

  The aperture ring 3 of this embodiment is manufactured by injection molding using a synthetic resin material, and its thickness is basically the same as that of the first embodiment. Moreover, the point which the seven cam grooves 3a and the tooth | gear part 3b are formed is also the same. A difference is that a lightening portion 3c is formed between adjacent cam grooves 3a in order to reduce the weight without making the aperture ring 3 thinner. Further, when the large grooved portion 3c is formed in addition to the cam groove 3a as described above, there is no problem with the conventional metal diaphragm ring. In this case, the cam groove 3a may be distorted and the shape of the cam groove 3a may be distorted, making it impossible to perform predetermined aperture control. Therefore, in this embodiment, in order to prevent the occurrence of such a situation, the rib 3d is formed on the subject side along the edge of each cam groove 3a.

  In this embodiment, the aperture ring 3 having such a shape can be manufactured at a lower cost than a conventional metal aperture ring. Further, unlike the conventional drawing ring, no rust prevention processing is required, so that the cost is also low. Moreover, since it is also possible to roughen the area | region of a required part with a metal mold | die similarly to Example 1, the secondary process is not required also from the point. Furthermore, since the aperture ring 3 of this embodiment is much lighter than the conventional aperture ring, it can be operated quickly even with a small force, and when it is driven by a motor as in this embodiment. Makes it possible to reduce power consumption. Further, it is possible to quiet the sound generated between the tooth portion 3b and the reduction gear 5i.

  In the case of the present embodiment, since seven large hollow portions 3c are formed in the aperture ring 3, in order to prevent the important cam groove 3a from being distorted, the rib 3d is attached to the cam groove 3a. Although it is formed along the edge, when the size of the thinned portion 3c is small, it may be formed in various shapes, for example, a plurality of linear ribs are radiated from the optical axis. Further, instead of forming the lightening portion 3c to reduce the weight, the basic thickness of the aperture ring 3 is reduced by reducing the weight by forming various shapes of ribs to increase the strength. You can do that.

  Next, the fourth embodiment will be described with reference to FIGS. 7 and 8. The difference between the present embodiment and the first embodiment is that only the shape of a part of the aperture ring is different. Therefore, in FIGS. 7 and 8, the same reference numerals as those of the first embodiment are also given to the aperture ring of the present embodiment. In addition, since each other member and site | part are substantially the same as the case of Example 1, the same code | symbol as Example 1 is also attached to them, and description is abbreviate | omitted. The operation of the present embodiment is substantially the same as that of the first embodiment. Therefore, the description of the operation is also omitted.

The aperture ring 3 of the present embodiment is manufactured by injection molding using a synthetic resin material as in the case of the first and third embodiments. Also in the present embodiment, as in the case of the third embodiment, in addition to the seven cam grooves 3a and the tooth portions 3b, the narrowed portion 3c is provided between the adjacent cam grooves 3a. Is forming. However, the rib 3d in Example 3 is not formed. In the case of the third embodiment, the cam groove 3a and the thinned portion 3c are formed as through holes. However, in this embodiment, the shape of the subject is closed. Accordingly, the cam groove 3a becomes concave groove, but the hollow portions 3c has a thin portion, the present embodiment, by adopting such a shape, maintaining a predetermined strength, are deformed Dzu Raku .

  In the present embodiment, the aperture ring 3 having such a shape can be manufactured at a lower cost than a conventional metal aperture ring. Further, unlike the conventional drawing ring, no rust prevention processing is required, and this is also low in cost. Moreover, since it is also possible to roughen the area | region of a required part with a metal mold | die like Example 1 or Example 3, secondary processing is not required also from the point. Furthermore, since the aperture ring 3 of this embodiment is much lighter than the conventional aperture ring, it can be operated quickly even with a small force, and when driven by a motor as in this embodiment. Makes it possible to reduce power consumption. Further, it is possible to quiet the sound generated between the tooth portion 3b and the reduction gear 5i.

  In the case of the aperture ring 3 of the present embodiment, the lightening is achieved by forming the thinned portion (thin portion) 3c, but a predetermined strength can be ensured and the aperture blade 4 is engaged. When the fitting state between the pin 4b and the cam groove 3a can be suitably maintained, the overall thickness of the aperture ring 3 is reduced without forming the thinned portion (thin portion) 3c, thereby reducing the weight. There is no problem.

It is a top view of Example 1 which shows the control state of a maximum aperture stop. It is sectional drawing of FIG. It is a top view of Example 1 which shows the control state of the minimum aperture stop. 6 is a cross-sectional view for explaining Example 2. FIG. It is a top view of Example 3 which shows the control state of the largest aperture opening. It is sectional drawing of FIG. It is a top view of Example 4 which shows the control state of the largest aperture opening. It is sectional drawing of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ground plate 1a, 2a Opening part 2 Cover plate 3 Diaphragm ring 3a Cam groove 3b Tooth part 3c Thickening part 3d Rib 4 Diaphragm blade 4a Shaft pin 4b Engaging pin 5 Step motor 5a 1st attachment plate 5b 2nd attachment plate 5c Rotation Child 5d, 5j Shaft 5e, 5f Yoke 5g, 5h Coil 5i Reduction gear

Claims (3)

A base plate having a circular exposure opening centered on the optical axis, and each having an engagement pin, and is rotatably attached to the base plate around the exposure opening. A plurality of aperture blades that are rotated between a maximum aperture control position and a minimum aperture control position by operating the engagement pin, and the optical axis rotates around the exposure aperture. a plurality of cam grooves and adjacent said cam groove formed plurality of lightening portions have that synthetic resin squeeze ring has between each other for operating the engagement pin by the arrangement has been provided the rotary as Driving means for reciprocatingly rotating the aperture ring, and a rib is integrally formed along an edge of the cam groove on at least one surface of the aperture ring. Aperture device. The aperture ring is characterized in that a part of the inner diameter surface and at least a surface opposite to the ground plane and close to the photographing optical path are roughened by integral molding. The diaphragm device for a camera according to claim 1 . It said drive means, a possible reciprocal rotary motor, the diaphragm ring, according to claim 1 or 2, characterized in that a tooth portion for meshing with the gear is rotated by the motor Camera aperture device.

Images