JP4216704B2 - Exposure control device for camera - Google Patents

Description

  The present invention relates to an exposure amount control device for a camera that allows an ND filter plate to face an exposure opening and dimming subject light.

  ND filters, which are known as one of exposure control means in still cameras and video cameras, were made of glass in the past, and many of them were detachable from the front of the lens, but recently most of them are synthetic resins. It is made of and is often built into the camera. In addition, when incorporated in the camera, an ND filter plate is attached to one surface of a filter mounting member (which may be a diaphragm blade), so that it is configured as a filter blade, and the drive means reciprocates the filter blade. It is common to move the ND filter plate back and forth to the exposure aperture by operating (rotating or straightly moving).

When the ND filter plate is attached to the filter mounting member, it is usually applied with an adhesive (for example, see Patent Document 1), but the adhesive protrudes from the adhesive surface or warps the ND filter plate after adhesion. In order to solve the problem of occurrence of the problem, there is also known one that is fixed by caulking (see Patent Document 2). In either case, the ND filter plate is often configured to reciprocate within the blade chamber formed between the two ground plates together with the filter mounting member. If it is not taken, it will come into sliding contact with one of the main plates, and the sliding contact surface will be damaged. Therefore, in order to eliminate the occurrence of such scratches, the ground plate facing the ND filter plate is provided with a recess in which the ND filter plate can operate, and the ND filter plate is slidably contacted with the ground plate. It is known that the filter mounting member is brought into slidable contact (see, for example, Patent Document 3).
JP-A-10-133253 JP 2002-365893 A JP 2003-5251 A

  Recently, with the miniaturization of the camera, the exposure control device including the movable ND filter plate as described above is also required to be small, thin, and low in cost. In particular, with the rapid progress of digital cameras (digital still cameras, digital video cameras, cameras for information terminal devices, surveillance cameras, etc.), the degree of demand has become stronger. Therefore, from such a viewpoint, when the configurations described in Patent Documents 2 and 3 are viewed, it must be said that there is a problem that requires improvement.

  That is, along with the miniaturization of the exposure control device, the filter mounting member has to be a considerably small member, but an ND filter plate that is smaller than the small member, and part of it. The fact that it must be attached by means of a very difficult work, regardless of whether the attachment method is an adhesion method or a caulking method, and an increase in cost cannot be avoided. Moreover, even if a recess for receiving the ND filter plate is provided on the ground plate surface facing the ND filter plate as in the configuration described in Patent Document 3, the depth of the recess is the thickness of the ND filter plate. In addition to the minute, even if the ND filter plate is slightly warped due to the effect of adhesion, etc., it must be set to a dimension that has enough margin to avoid contact, so inevitably the thickness of the ground plate Therefore, it is difficult to make the apparatus thinner than ever.

  The present invention has been made to solve such a problem, and the object of the present invention is to constitute a filter blade that can be advanced and retracted to the exposure aperture with only one ND filter plate. Nevertheless, the effective area covering at least the exposure aperture of the filter blade is not damaged at all by the advance / retreat operation, and the exposure amount for the camera is suitable for downsizing, thinning and cost reduction. It is to provide a control device.

In order to achieve the above object, an exposure amount control device for a camera according to the present invention is provided for a photographing optical path that regulates an exposure opening by at least one of a first ground plane having an opening for the photographing optical path and the opening. A second base plate having an opening and constituting a blade chamber between the first base plate and a single ND filter plate, and a partial area as an effective area covering the exposure opening A filter blade that is rotatably attached to one of the two ground plates in the blade chamber and is advanced and retracted to the exposure opening, and each of the two ground plates is at least when the filter blade is in operation. A step surface having a step smaller than the thickness dimension of the filter blade is formed so that the surface facing the effective region does not contact the region.

In that case, at least one of the step surfaces formed on the two ground planes may be the bottom surface of the recess, or formed along at least one of the two sides of the effective region in the operation direction. The step surface formed on one of the two ground planes may be the bottom surface of the recess, and the step surface formed on the other is the top surface of the effective area. It may be the top surface of the protrusion formed along at least one of the two sides in the operation direction. Further, wherein the hand of two of the main plate, may be through-hole shape in which the bottom portion of the concave portion is removed is formed.

  And when forming a recessed part in a metal base plate as said level | step-difference part, forming by a chemical etching method is preferable. Further, when the camera exposure amount control device as described above is configured as a unit together with the shutter device, an opening for the photographing optical path that restricts the exposure opening by at least one of the openings of the two ground planes. A second blade chamber is formed between one of the two ground plates, and a third ground plate having a shutter blade rotatably attached thereto is provided in the second blade chamber. Is preferred.

In the camera exposure control apparatus according to the present invention, the filter blades are made of a single ND filter plate. Therefore, compared with the conventional configuration in which the ND filter plate is attached to the filter attachment member, enables cost, and because the filter blade root can be made smaller than the conventional filter mounting member, which is advantageous to the miniaturization of the planar shape of the device. In addition, the two ground planes constituting the blade chamber are formed with recesses and ridges, but the depth of the recesses and the height of the ridges are very small. As described above, it is necessary to form the depth of the recess in consideration of the thickness of the ND filter plate attached to the filter mounting member as well as the size of the ND filter plate that does not come into contact even if the ND filter plate is slightly warped. It is possible to reduce the thickness.

  The embodiment of the present invention will be described with reference to two illustrated examples. In any of these embodiments, the filter device and the shutter device are configured as a single unit, which can be used for both digital cameras and film cameras. In this case, a case where the digital still camera is adopted will be described. 1 to 3 are for explaining the first embodiment, FIG. 1 is a plan view showing an initial state, and FIG. 2 is a cross-sectional view of the main part of FIG. 3 is a plan view showing a state immediately after the end of photographing. 4 to 6 are for explaining the second embodiment. FIG. 4 is a plan view showing an initial state, and FIG. 5 is a cross-sectional view of the main part of FIG. 6 is a plan view showing a state immediately after the end of photographing.

  First, the structure of a present Example is demonstrated using FIG.1 and FIG.2. As described above, in this embodiment, the filter device and the shutter device are configured as one unit. Therefore, the main ground plate 1, the middle ground plate 2, and the auxiliary ground plate 3 are attached to each other at a predetermined interval, and two blade chambers are formed between them. These base plates 1, 2 and 3 are formed with circular openings 1a, 2a and 3a for photographing optical paths in substantially central portions. In the case of the present embodiment, the diameter of the opening 2a is set. It is smaller than the diameters of the openings 1a and 3a and regulates the exposure opening. However, it goes without saying that the opening 1a or the opening 3a may regulate the exposure opening. Although the ground plates 1, 2, and 3 have similar outer shapes, in FIG. 1, a part of the main ground plate 1 and the middle ground plate 2 are cut. Further, the mutual mounting configuration of the base plates 1, 2, 3 and the mounting configuration to the camera are not shown.

  The main base plate 1 is made of synthetic resin, and has two elongated holes 1b and 1c having an arc shape slightly below the both sides of the opening 1a. On the back side, three shafts 1d, 1e, and 1f and six stopper pins 1g, 1h, 1i, 1j, 1k, and 1m having various cross-sectional shapes are formed. In FIG. 1, since a part of the main ground plate 1 is cut and shown, only the two stopper pins 1g and 1k are shown in cross section.

  The intermediate plate 2 is made of metal and has a hole 2b through which the stopper pin 1m passes. Further, although not clearly shown, long holes having the same shape as those are formed at positions corresponding to the long holes 1b and 1c of the main ground plate 1, and the shafts 1d, 1e and 1f of the main ground plate 1 are provided. A hole for penetration is formed. Furthermore, on the back side, an arc-shaped recess 2c centering on the shaft 1f is formed by chemical etching so that the diameter of the opening 2a is a width dimension and is continuous with the opening 2a. 2 shows most of the region cut away, so that the overall planar shape can be seen from FIG.

  Although the auxiliary ground plate 3 is made of metal and has the same outer shape as the intermediate ground plate 2 and is not clearly shown, a long hole having the same shape is formed at a position corresponding to the long hole 1c of the main ground plate 1. Is formed. Moreover, the hole of the same shape is formed in the position corresponding to the hole 2b of the center board 2, and the front-end | tip of the stopper pin 1m is inserted there. A hole for inserting the tip of the shaft 1f of the main base plate 1 is also formed. Further, in the region facing the concave portion 2c of the intermediate plate 2, an arc-shaped concave portion 3b centering on the shaft 1f is formed so that the diameter of the opening 3a is a width dimension and is continuous with the opening 3a. It is formed by chemical etching processing in the same way as.

  Two shutter blades 4 and 5 are disposed in a blade chamber formed between the main base plate 1 and the intermediate base plate 2, and are rotatably attached to the shafts 1 d and 1 e of the main base plate 1. And these long holes 4a and 5a are made to face the long hole 1b of the main ground plate 1. FIG. One filter blade 6 is disposed in the blade chamber formed between the intermediate plate 2 and the auxiliary plate 3. The filter blade 6 is obtained by cutting a synthetic resin ND filter plate into a shape shown in the figure, and is rotatably attached to the shaft 1 f of the main base plate 1. The long hole 6 a is changed to the long hole 1 c of the main base plate 1. I ’m here. As described above, in the case of the present embodiment, the recesses 2c and 3b of the intermediate base plate 2 and the auxiliary base plate 3 are formed by chemical etching, and as can be seen from FIG. The dimension is considerably smaller than the thickness dimension of the filter blade 6 so that the reference thickness dimension of the intermediate base plate 2 and the auxiliary base plate 3 can be minimized.

  In FIG. 1, two current control type motors called moving magnet type motors and the like are attached to the surface side of the main base plate 1 (that is, the upper surface side in FIG. 2). This type of motor is a motor in which when a stator coil is energized, a rotor having a permanent magnet rotates within a predetermined angular range in a direction corresponding to the energization direction. Are known. In the case of the present embodiment, the most typical configuration of this type of motor as known in Japanese Patent Application Laid-Open No. 2000-60088 is adopted, but the configuration is too well known. Therefore, a specific configuration is not shown, and only the rotors 7 and 8 are shown by two-dot chain lines in FIG.

  The rotors 7 and 8 are provided with output pins 7a and 8a that rotate integrally at the radial position of the rotating shaft. One output pin 7a passes through the long hole 1b and fits into the long holes 4a and 5a of the shutter blades 4 and 5, and the tip of the output pin 7a has the same shape as the long hole 1b and is formed in the center plate 2. It is inserted into a long hole that is not specified. Further, the other output pin 8a passes through the long hole 1c and a long hole of the same shape (not shown) formed in the center plate 2, and is fitted into the long hole 6a of the filter blade 6, and the tip thereof is The long hole 1c has the same shape as that of the long hole 1c, and is inserted into a long hole which is not clearly shown in the auxiliary base plate 3.

  Next, the operation of this embodiment will be described. For convenience of explanation, the motor having the rotor 7 is called a first motor, and the motor having the rotor 8 is called a second motor. FIG. 1 shows an initial state when the unit of this embodiment is adopted in a digital still camera. That is, in this initial state, the power is on, and the shutter blades 4 and 5 fully open the opening 2a (exposure opening). Therefore, the solid-state image sensor is exposed to subject light, and the subject image can be observed on a monitor. On the other hand, the filter blade 6 does not cover the opening 2a, so that the subject image can be easily observed on the monitor.

  When the release button is pressed at the time of shooting, first, based on the measurement result of the subject light, it is determined whether to shoot with the subject light amount reduced or not taken. Then, when shooting with the amount of subject light reduced, a positive current is supplied to the stator coil of the second motor. Thereby, the rotor 8 is rotated counterclockwise, and the filter blade 6 is rotated counterclockwise by the output pin 8a. For this reason, the filter blade 6 enters the opening 2a and stops immediately after contacting the stopper pin 1m immediately after completely covering the opening 2a.

  Thereafter, when the charge accumulated in the solid-state imaging device is released by a signal from the exposure control circuit, exposure for photographing starts and new charges are accumulated in the solid-state imaging device. When a predetermined time elapses, a positive current is supplied to the stator coil of the first motor by a signal from the exposure control circuit. Thereby, the rotor 7 is rotated counterclockwise, and the shutter blades 4 and 5 are rotated in opposite directions by the output pin 7a. Therefore, the shutter blades 4 and 5 close the opening 2a, and immediately after the opening 2a is completely closed, the shutter blade 4 contacts the stopper pin 1i and the shutter blade 5 contacts the stopper pin 1j and stops. To do. FIG. 3 shows a state in which the operation of the shutter blades 4 and 5 is thus stopped.

  In this way, when the opening 2a is closed and the closing operation of the shutter blades 4 and 5 is stopped, the imaging information is transferred to the storage device in that state. When the transfer is completed, the stator coil of the first motor is energized in the opposite direction to the above case. Thereby, the rotor 7 is rotated clockwise in FIG. 3, and the shutter blades 4 and 5 are opened by the output pin 7a. Then, when the opening 2a is fully opened, the shutter blades 4 and 5 come into contact with the stopper pins 1g and 1h and stop immediately thereafter. On the other hand, the stator coil of the second motor is also energized in the opposite direction to the above case, so the rotor 8 is rotated clockwise in FIG. 3, and the filter blade 6 is moved by the output pin 8a. Rotate clockwise. And the filter blade | wing 6 contact | abuts to the stopper pin 1k, and stops, after retreating completely from the opening part 2a. Thereafter, when energization of the stator coils of the two motors is cut off, the initial state of FIG. 1 is obtained.

  In the above description of the operation, the shooting was performed while reducing the amount of light of the subject light. However, when shooting is performed without reducing the amount of light of the subject light, the stator coil of the second motor is energized from the beginning. Needless to say, the shutter blades 4 and 5 are merely reciprocated by the first motor.

  Thus, according to the present embodiment, since the filter blade 6 is manufactured only with the ND filter plate, as compared with the conventional one manufactured by attaching the ND filter plate to the filter mounting member, The cost can be reduced, and the filter blade 6 can be made smaller than the conventional filter mounting member, which is advantageous for downsizing the planar shape of the apparatus. Further, in this embodiment, the filter blade 6 is made of only a relatively soft ND filter plate. However, in the operation range of the effective region of the filter blade 6 covering the opening 2a in FIG. Since the concave portions 2c and 3b are formed on the surfaces of the auxiliary ground plate 2 and the auxiliary base plate 3, their bottom surfaces are stepped surfaces, and the effective area is never damaged during operation.

  Furthermore, in the case of the present embodiment, the intermediate base plate 2 and the auxiliary base plate 3 are made of metal, and the recesses 2c and 3b are formed by chemical etching, and the depth thereof is such that the filter blade 6 is not in contact. Therefore, the main plates 2 and 3 can be thinned, and as a result, the entire unit can be thinned. However, the present invention is not limited to the base plates 2 and 3 being made of metal, but may be made of synthetic resin, and the recesses 2c and 3b may be simultaneously formed at the time of molding. Moreover, even if the base plates 2 and 3 are made of metal, the formation of the recesses 2c and 3b is not limited to the one formed by the chemical etching method. Furthermore, in the present invention, regardless of whether the base plates 2 and 3 are made of metal, at least one of the recesses 2c and 3b may be formed as a through hole with the bottom portion removed.

  Next, Embodiment 2 will be described with reference to FIGS. 4 to 6. In those drawings, the same members and parts as those in Embodiment 1 are denoted by the same reference numerals. For this reason, the configuration of the present embodiment will be described only with respect to differences from the first embodiment. In the middle plate 2 of the present embodiment, as in the case of the first embodiment, a recess 2c is formed by chemical etching. However, the recess 3b in the first embodiment is not formed in the auxiliary base plate 3. Instead, in the present embodiment, two protrusions 3c and 3d are formed in an arc shape centered on the shaft 1f on the metal auxiliary ground plate 3 by embossing, and the top surfaces thereof are stepped surfaces. However, the protrusions 3c and 3d are formed on opposing surfaces slightly outward from both sides along the operation locus of the effective region of the filter blade 6. Other configurations are substantially the same as those in the first embodiment.

  FIG. 4 shows an initial state as in FIG. 1 of the first embodiment, and FIG. 6 shows a state immediately after the end of photographing, as in FIG. 3 of the first embodiment. Therefore, as can be seen from the comparison, the operation of this embodiment performed by the rotation of the rotors 7 and 8 is basically the same as that of the first embodiment. Therefore, a specific description of operation is omitted. By the way, in the case of Example 1, except for the area | region of the diameter (substantially the same diameter as the opening part 1a) where the surface at the side of the auxiliary ground plate 3 of the filter blade 6 is slightly larger than the diameter of an effective area | region at the time of operation | All were in sliding contact with the auxiliary base plate 3. However, in the case of the present embodiment, a region much smaller than that is only in sliding contact with the top surfaces of the two elongated arc-shaped protrusions 3c and 3d. Therefore, the frictional resistance is less than that in the case of the first embodiment, and the filter blade 6 can be smoothly operated correspondingly. In the present embodiment, the auxiliary base plate 3 is made of metal, but the present invention does not preclude making of the synthetic resin.

  Thus, also in the case of the present embodiment, since the filter blade 6 is manufactured only by the ND filter plate, it is compared with the conventional filter blade 6 manufactured by attaching the ND filter plate to the filter mounting member. Further, the cost can be reduced and the filter blade 6 can be made smaller than the conventional filter mounting member, which is advantageous for downsizing the planar shape of the apparatus. The filter blade 6 is made of only a relatively soft ND filter plate. On the other hand, the bottom surface of the recess 2c is a stepped surface, and on the other hand, the top surfaces of the protrusions 3c and 3d are stepped surfaces. Therefore, the effective area of the filter blade 6 is not slidably brought into contact with the intermediate base plate 2 and the auxiliary base plate 3 during operation, and there is no scratch. Furthermore, in the case of the present embodiment, the intermediate base plate 2 and the auxiliary base plate 3 are made of metal, and on the one hand, the concave portion 2c is formed shallow by chemical etching, and on the other hand, the protrusions 3c and 3d are formed by embossing. Since it is formed low, the entire unit can be made thin.

  In the present embodiment, the recess 2c is formed in the intermediate base plate 2 and the ridges 3c and 3d are formed in the auxiliary base plate 3. However, two ridges are formed in the intermediate base plate 2, and May be formed in the same manner as in the first embodiment. In the present embodiment, the two protrusions 3c and 3d are formed on the auxiliary base plate 3, but only one of them may be used. The same applies when forming. Furthermore, the top surfaces of the ridges 3c and 3d of the present embodiment are all formed as continuous surfaces having the same height, but at least one of the ridges is not a flat surface having the same height. It can be formed as a continuous ridge. Moreover, although the protrusions 3c and 3d of the present embodiment are formed in an arc shape centered on the shaft 1f, the protrusions of the present invention are not limited to the arc shape.

2 is a plan view showing an initial state of Example 1. FIG. It is principal part sectional drawing of FIG. It is a top view of Example 1 which shows the state immediately after completion | finish of imaging | photography. 6 is a plan view showing an initial state of Example 2. FIG. It is principal part sectional drawing of FIG. It is a top view of Example 2 which shows the state immediately after completion | finish of imaging | photography.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main ground plate 1a, 2a, 3a Opening 1b, 1c, 4a, 5a, 6a Long hole 1d, 1e, 1f Shaft 1g, 1h, 1i, 1j, 1k, 1m Stopper pin 2 Middle ground plate 2b Hole 2c, 3b Recess 3 Auxiliary base plate 3c, 3d Projection 4,5 Shutter blade 6 Filter blade 7,8 Rotor 7a, 8a Output pin

Claims (7)

A vane chamber is formed between the first ground plane having an aperture for the imaging optical path and an aperture for the imaging optical path that regulates the exposure aperture by at least one of the apertures, and the first ground plane. A second ground plate, and a single ND filter plate, and a part of the region is an effective region that covers the exposure opening, and is rotatably attached to one of the two ground plates in the blade chamber. comprise a filter blade is caused to advance and retreat in, wherein the two ground plates, each of the thickness of the filter blade at least the effective area surface facing said filter blade so as not to contact with the region at the time of operation of the An exposure amount control device for a camera, characterized in that a step surface having a step smaller than the height is formed.   2. The exposure control apparatus for a camera according to claim 1, wherein at least one of the step surfaces formed on the two ground planes is a bottom surface of the recess.   At least one of the step surfaces formed on each of the two ground planes is a top surface of a ridge formed along at least one of both sides in the operation direction of the effective region. Item 2. The exposure control apparatus for a camera according to Item 1.   At least one of the step surfaces formed on the two ground planes is a bottom surface of the recess, and the step surface formed on the other is formed along at least one of both sides of the effective region in the operation direction. The camera exposure amount control device according to claim 1, wherein the exposure amount control device is a top surface of the projected ridge. The two in the hand of the base plate, the camera exposure control device according to claim 2 or 4, characterized in that the through-hole shape in which the bottom portion of the concave portion is removed is formed.   5. The exposure control apparatus for a camera according to claim 2, wherein the recess is formed by a chemical etching method.   An opening for a photographing optical path that regulates an exposure opening by at least one of the openings of the two ground planes, and a second blade chamber is formed between one of the two ground planes, The camera exposure amount control device according to any one of claims 1 to 6, further comprising a third base plate rotatably mounted with shutter blades in the second blade chamber.