JP2007010808A - Mirror driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the positioning accuracy of a sub mirror with simpler constitution. <P>SOLUTION: The mirror driving device 10 includes: a translucent main mirror 16; and the sub mirror 20 connected to the back of the main mirror 16. The main mirror 16 and the sub mirror 20 ascend/descend while they are interlocked with each other by a quadric link mechanism. The quadric link mechanism includes: a first arm 26 connecting a first shaft 30 positionally fixed and a second shaft 32 connected to the upper end of the main mirror; and a second arm 28 connecting a fourth shaft 36 positionally fixed and a third shaft 34 inserted through the middle of the main mirror 16 and the upper end of the sub mirror 20. Then, the first arm 26 and the second arm 28 are interlocked to perform driving so as to maintain the distance relation of the respective shafts, whereby both mirrors 16 and 20 ascend/descend. Since one (the third shaft 34) of the shafts constituting the quadric link mechanism is connected to the sub mirror 20, the positional accuracy of the sub mirror 20 is improved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mirror driving device that is built in a single-lens reflex camera and controls a traveling direction of field light by driving a mirror.

  2. Description of the Related Art Conventionally, single-lens reflex cameras that can display the same object scene image as an imaged object field image on an optical fundar are widely known. In a single-lens reflex camera, a main mirror is obliquely disposed between a photographic lens system and an imaging device (film surface in the case of a film camera), and the object field light from the photographic lens system is optically findered by the main mirror. Can be folded. The main mirror is composed of a half mirror that can reflect part of the object scene light and transmit part of the object field light. Behind the main mirror, a sub-mirror is provided obliquely with respect to the main mirror. The sub mirror bends the optical path of the field light transmitted through the main mirror and guides it to an AF sensor or an AE sensor provided at the bottom of the camera. Both the main mirror and the sub mirror are provided so as to be movable up and down. When the object scene image is captured, the main mirror and the sub mirror are raised to guide the object field light to the image sensor or the film surface.

  Conventionally, a number of techniques have been proposed for the lifting mechanism of the main mirror and the sub mirror. For example, Patent Document 1 discloses a mirror driving device that swings back a main mirror. This mirror driving device has a configuration similar to a four-bar linkage mechanism, and the main mirror rises while swinging back and rotating. By adopting the swing back method, the movable range of the main mirror can be reduced, which can contribute to the miniaturization of the camera. Further, one end of the sub mirror is rotatably connected to the main mirror so that it can be lifted and lowered together with the main mirror. The sub mirror is urged in a direction to be brought into close contact with the main mirror by the urging means. In addition, the sub mirror is provided with a positioning member that guides the sub mirror in a direction in which the sub mirror is detached from the main mirror as the main mirror is lowered. Thereby, a submirror can be made to interlock | cooperate with the motion of the raising / lowering of a main mirror. As a result, both the main mirror and the sub mirror can be raised and lowered with a relatively simple configuration.

Japanese Patent Laid-Open No. 7-13260

  However, in the case of the mirror driving device described in Patent Document 1, there is a problem that the positional accuracy of the sub mirror is lowered. As described above, the sub-mirror guides part of the object scene light to the AF sensor or the AE sensor. Therefore, when the position accuracy of the sub mirror is poor, the object field light cannot be reliably guided to the AF sensor and the AE sensor, and as a result, the focusing accuracy and the automatic exposure accuracy are lowered. Here, in the mirror driving device described in Patent Document 1, the sub mirror is connected to the main mirror, and the positional accuracy depends on the positional accuracy of the main mirror and the mounting accuracy of the sub mirror to the main mirror. The position accuracy of the main mirror depends on the accuracy of the four axes and the two arms constituting the substantially four-bar linkage mechanism. Therefore, the position accuracy of the sub mirror is affected by all of the accuracy of the four axes and the two arms constituting the substantially four-bar linkage mechanism, and the accuracy of attachment to the main mirror. As a result, it is difficult to position the submirror with high accuracy.

  Moreover, in the mirror drive device described in Patent Document 1, a guide shaft, which is one of the four shafts constituting the substantially four-bar linkage mechanism, is moved along a guide groove provided in the mirror box. At this time, high friction is generated between the guide shaft and the guide groove, reducing the operating efficiency of the mirror.

  Accordingly, an object of the present invention is to provide a mirror driving device that can improve the positional accuracy of a submirror more easily. Another object of the present invention is to improve the operating efficiency of the mirror.

  The mirror driving device of the present invention includes a main mirror whose angle with respect to the optical axis of the photographic lens system is variable along with its up and down movement, and a sub mirror that is connected behind the main mirror and can be moved up and down in conjunction with the up and down movement of the main mirror. A first axis provided on the fixing member and a second axis connected to the upper end of the main mirror, the first arm being rotatable about the first axis, and the fixing member A second arm that connects the fourth axis provided on the third axis and the third axis connected to the middle part of the main mirror and the upper end of the sub-mirror, and a second arm that is rotatable about the fourth axis; The main mirror and the sub mirror are moved up and down in conjunction with each other by rotating and driving the first arm and the second arm while maintaining the distance relationship between the second axis and the third axis.

  In a preferred embodiment, the first arm follows the second arm. In another preferred aspect, the sub-mirror changes the angle with respect to the main mirror by rotating around the third axis in conjunction with the raising / lowering operation. At this time, an elastic member that urges the sub mirror in a direction in which the angle with respect to the main mirror increases, a rotating member that does not change the angle with respect to the sub mirror and rotates about the third axis together with the sub mirror, and one end of the rotating member are provided. And a cam groove that is provided in the fixing member and that engages with the engagement member and restricts the movement path of the engagement member when the main mirror is raised, and is regulated by the cam groove. The moving path of the engaging member is preferably a path in which the rotating member is gradually inclined in the direction in which the sub mirror is in close contact with the main mirror as the main mirror is raised.

  Here, the connection relationship between each axis and each mirror may be a direct connection relationship or a connection relationship via a mirror housing member such as a mirror frame.

  According to the present invention, the third shaft, which is one of the shafts constituting the four-bar linkage mechanism, is connected to the sub mirror. Therefore, the position accuracy of the sub mirror does not depend on the position accuracy of the main mirror, and as a result, the position accuracy of the sub mirror can be improved. Further, the four shafts constituting the four-bar linkage mechanism do not come into contact with other members during the movement. Therefore, friction does not occur during movement, and drive efficiency can be improved.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a mirror driving device 10 according to an embodiment of the present invention as viewed from the front side (photographing lens system side). FIG. 2 is a perspective view of the mirror driving device 10 as seen from the back side (image sensor or film side). FIG. 3 is a side view of the mirror driving device 10. Although only one side of the mirror box 24 is shown in the drawing, the mirror box 24 actually has four sides and surrounds the four directions of the mirror driving device 10.

  The mirror driving device 10 is disposed inside a single-lens reflex camera, specifically, between a photographing lens system and an imaging device (a film surface in the case of a film camera). Then, the traveling direction of the object scene light from the photographing lens system is changed by appropriately rotating the main mirror 16. Further, the sub mirror 20 is also moved up and down and opened and closed in conjunction with the main mirror 16 to guide the AF light to the AF sensor 100.

  The main mirror 16 is a semi-transmissive mirror (half mirror) that transmits part of light and reflects part of the light. The main mirror 16 can be moved up and down by a four-bar linkage mechanism described later. When descending, the main mirror 16 is obliquely installed on the optical axis of the taking lens system. Then, a part of the object field light guided by the photographing lens system is reflected and a part of the light is transmitted. The object field light reflected by the main mirror 16 is guided to the optical viewfinder by the viewfinder optical system. The object field light transmitted through the main mirror 16 is reflected by the sub-mirror 20 located behind the main mirror 16 and guided to the AF sensor 100. At the time of shooting the object scene image, the main mirror 16 is raised while rotating, and finally becomes substantially parallel to the optical axis at a position away from the optical axis of the taking lens system. Thereby, all of the field light guided by the photographing lens system can reach the image sensor (or the film surface), and suitable imaging can be performed.

  The main mirror 16 is accommodated in the main mirror frame 18. The main mirror frame 18 is a substantially box-shaped member in which a concave portion for accommodating the main mirror 16 is formed on the upper surface. A substantially rectangular through-hole 18 a is formed in the approximate center of the main mirror frame 18 so that the object field light transmitted through the main mirror 16 advances behind the main mirror 16. A second shaft 32 and a third shaft 34, which are shafts constituting a four-bar link, are inserted through the upper end and middle portion of the side surface of the main mirror frame 18, respectively. As will be described in detail later, the second shaft 32 and the third shaft 34 move in conjunction with each other by driving the second arm 28. Accordingly, the position and angle of the main mirror frame 18 through which the second shaft 32 and the third shaft 34 are inserted also vary by the driving of the second arm 28. As a result, the up and down movement of the main mirror frame 18 and consequently the main mirror 16 is realized.

  The sub mirror 20 is a mirror that reflects almost all of the received light, and is provided behind the main mirror 16. The sub mirror 20 is provided behind the main mirror 16 and is configured to be movable up and down in conjunction with the main mirror 16. In addition, an opening / closing operation for changing the angle with respect to the main mirror 16 is also performed in conjunction with the lifting operation. That is, when descending, the sub mirror 20 is positioned in an open state having an inclination of approximately 90 degrees with respect to the main mirror 16 and approximately 135 degrees with respect to the optical axis of the photographing lens system. Then, the object field light transmitted through the main mirror 16 is reflected and guided to the AF sensor 100. When the main mirror 16 is raised, the sub mirror 20 is also raised. At this time, the sub mirror 20 gradually decreases the angle with respect to the main mirror 16 as it rises, and finally enters a closed state in close contact with the main mirror 16. Thereby, the object field light guided by the photographing lens system can reach the image sensor (or film surface) without being blocked by the sub mirror 20.

  The sub-mirror 20 is housed in a sub-mirror frame 22 that is a substantially box-like member having a concave portion for housing the sub-mirror 20 on the upper surface. A third shaft 34 is inserted through the upper end of the side surface of the sub mirror frame 22, and the position and angle of the main mirror frame 18 are changed according to the driving of the second arm 28. By driving the sub-mirror frame 22, the sub-mirror 20 is moved up and down.

  Here, the third shaft 34 is inserted through both the sub mirror frame 22 and the main mirror frame 18. Accordingly, the third shaft 34 also functions as a connecting member that connects both the frames. One end of the third shaft 34 is connected to the second arm 28 and functions as one of the shafts constituting a four-bar linkage mechanism described later. Further, the third shaft 34 also functions as a rotation shaft for realizing the opening / closing operation of the sub mirror 20. That is, the sub mirror 20 is driven to rotate about the third axis 34 when opening and closing. In order to realize this rotational drive, an eccentric pin 44 is connected to the other end of the third shaft 34. The eccentric pin 44 is a long member whose angle with respect to the sub mirror 20 does not change, and a protruding member 46 projects from the tip of the eccentric pin 44. The projecting member 46 engages and abuts on a cam groove 48 formed in the mirror box 24 which is a fixing member, whereby the closing operation of the sub mirror 20 is realized. An open / close torsion spring is inserted through the third shaft 34. One end of the open / close torsion spring is locked to the bottom surface of the main mirror frame 18 and the other end is locked to the top surface of the sub mirror frame 22, and is biased in a direction to widen the angle between the main mirror frame 18 and the sub mirror frame 22. Yes. The opening operation of the sub mirror 20 is realized by the elastic force of the torsion spring. That is, the opening / closing operation of the sub mirror 20 (angle fluctuation with respect to the main mirror 16) is realized by the raising / lowering operation of the sub mirror 20 (sub mirror frame 22) by the elastic force of the torsion spring and the contact relationship between the projection member 46 and the cam groove 48. Is done. The opening / closing mechanism will be described in detail later.

  The main mirror 16 (main mirror frame 18) and the sub mirror 20 (sub mirror frame 22) are moved up and down by a four-bar linkage mechanism. The four-bar linkage has four shafts and two arms. Of the four axes, the first axis 30 and the fourth axis 36 are fixed to the mirror box 24, and their positions are unchanged. On the other hand, of the four axes, the second axis 32 is connected to the upper end of the main mirror frame 18, and the third axis 34 is connected to the upper end of the sub mirror 20 and the middle part of the main mirror 16. The positions of the second shaft 32 and the third shaft 34 change as the first arm 26 and the second arm 28 are driven.

  The first arm 26 is an arm member that connects the position-fixed first shaft 30 and the position-variable second shaft 32. The first arm 26 is rotatable about the first shaft 30, and the position of the second shaft 32 is changed by the rotation operation of the first arm 26.

  The second arm 28 is an arm member that connects the position-fixed fourth shaft 36 and the position-variable third shaft 34. The fourth shaft 36 can be rotated by a motor (not shown), and the rotation of the fourth shaft 36 causes the second arm 28 to rotate about the fourth shaft 36. Then, when the second arm 28 rotates around the fourth axis 36, the position of the third axis 34 moves.

  A positioning torsion spring 40 is inserted through the fourth shaft 36. One end of the positioning torsion spring 40 is engaged with the second arm 28 and the other end is engaged with the first stopper 37. The first stopper 37 is a fixing member protruding from the mirror box 24. The positioning torsion spring 40 urges the second arm 28 so that the tip end (the third shaft 34 side) of the second arm 28 is directed downward.

  Further, a second stopper 38 and a third stopper 39, which are protruding members whose positions are fixed, are provided at predetermined positions of the mirror box 24. The second stopper 38 is a positioning member that regulates the position of the main mirror 16 by coming into contact with the lower end of the lowered main mirror frame 18. The third stopper 39 is a positioning member that regulates the position (angle) of the sub mirror 20 by contacting the lower end of the opened sub mirror frame 22. The first to third stoppers 37, 38, and 39 are all provided with a size that does not hinder the progress of the object field light.

  Next, the raising and lowering operation of the main mirror 16 and the sub mirror 20 in the mirror driving device 10 will be described with reference to FIGS. 4 to 6 are side views showing how the sub-mirror 20 and the main mirror 16 are raised and lowered, and show the lowered state, the rising state, and the raised state of the mirrors 16 and 20, respectively. In FIGS. 4 to 6, illustration of some members is omitted for the sake of clarity.

  As described above, in the mirror drive device 10 of the present embodiment, the four-arm link mechanism is configured by the two arms 26 and 28 and the four shafts 30 to 36. Of the four axes 30 to 36, the second axis 32 and the third axis 34 vary in position, but the distance between the axes (internode distance) is constant. The first arm 26 and the second arm 28 are driven in conjunction with each other so as to maintain the distance between the axes.

  In the lowered state of the main mirror 16 and the sub mirror 20, the second arm 28 maintains a predetermined inclination so that the upper end of the sub mirror 20, in other words, the third shaft 34 is at a predetermined position. The inclination angle of the second arm 28 is maintained by the contact relationship between the second stopper 38 and the main mirror 16. At this time, the first arm 26 rotates around the first shaft 30 and maintains the third shaft 34 at a predetermined position so that the distance between the third shaft 34 and the first shaft 30 is constant. Then, the positions of the second shaft 32 and the third shaft 34 connected to the upper end and the middle of the main mirror frame 18 are maintained at predetermined positions, so that the angle of the main mirror frame 18 and consequently the main mirror 16 The angle is maintained at a predetermined angle.

  When the main mirror 16 and the sub mirror 20 are raised, the fourth shaft 36 is rotated by a motor, and the second arm 28 is moved upward (clockwise in FIG. 5) against the urging force of the positioning torsion spring 40. Drive to rotate. As the second arm 28 is driven to rotate, the position of the third shaft 34 connected to the tip of the second arm 28 varies. The first arm 26 connected to the second shaft 32 is also raised so as to keep the distance between the third shaft 34 and the third shaft 34 that changes in position constant.

  At this time, the third axis 34 can move only on an arc centered on the fourth axis 36. Further, the second shaft 32 can move only on an arc centered on the first shaft 30. That is, the movement trajectory of both the second shaft 32 and the third shaft 34 is limited when moving. In order to keep the distance between the second shaft 32 and the third shaft 34 constant while satisfying the limitation of the movement locus, the angle between the second shaft 32 and the third shaft 34 must be changed. Therefore, when the position of the third shaft 34 rises due to the rise of the second arm 28, the second shaft 32 keeps the distance from the third shaft 34 constant while changing the angle with the third shaft 34. This change in angle is such that the inclination angle of the connecting line of the second shaft 32 and the third shaft 34 gradually and gradually approaches the parallel to the optical axis of the photographic lens system as the second arm 28 rises. ).

  If the inclination of the connecting line between the second shaft 32 connected to the upper end of the main mirror frame 18 and the third shaft 34 connected to the middle part of the main mirror frame 18 becomes moderate, it is natural that the main mirror 16 The inclination angle also becomes gentle. Therefore, when the second arm 28 is rotationally driven in the upward direction, the main mirror 16 is lifted while reducing the inclination angle.

  By further rotating the fourth shaft 36 and continuing the ascending rotational drive of the second arm 28, the main mirror 16 moves completely upward as shown in FIG. At this time, the angle of the connecting line between the second shaft 32 and the third shaft 34 is further reduced, and the main mirror 16 is substantially parallel to the optical axis of the photographing lens system. The upper end of the sub mirror frame 22 connected to the third shaft 34 together with the main mirror frame 18 also moves completely upward. As a result, the main mirror 16 and the sub mirror 20 are raised.

  As is clear from the above description, in the case of the present embodiment, by configuring the four-bar linkage mechanism, the position rise and angle change of the main mirror 16 can be realized simultaneously by driving only the second arm 28. At this time, the main mirror 16 moves while drawing a movement path of a substantially circular arc indicated by a one-dot chain line in FIGS. That is, the main mirror 16 has a so-called swing back motion. In the case of swingback, the drive range can be made smaller than when the main mirror 16 is driven to rotate around a single axis. As a result, the mirror driving device 10 itself can be made smaller, and the entire single-lens reflex camera can be downsized.

  Here, also in the mirror drive device 10 described in Patent Document 1, the main mirror 16 is swung back, and the drive range thereof is reduced. However, in the technique described in Patent Document 1, there are a large number of members related to the raising and lowering of the main mirror 16 and the sub mirror 20, and the configuration thereof is complicated. In particular, in Patent Document 1, the shaft constituting the substantially four-bar linkage mechanism and the sub-mirror frame are not directly connected. For this reason, the positional accuracy of the sub mirror is affected by the positional accuracy of the connecting member that connects the sub mirror frame and the main mirror frame in addition to the positional accuracy of the substantially four-bar linkage mechanism. Therefore, it is difficult to maintain the position of the sub mirror with high accuracy. On the other hand, in the present embodiment, the shaft (third shaft 34) constituting the four-bar linkage mechanism and the upper end of the sub mirror frame 22 are directly connected. Therefore, the position accuracy of the sub mirror 20 depends only on the position accuracy of the four-bar linkage mechanism, and the sub mirror 20 can be accurately positioned more easily. As a result, part of the object scene light can be more reliably guided to the AF sensor 100, and a more accurate AF operation can be performed.

  Moreover, in the mirror drive device described in Patent Document 1, the shaft connected to the main mirror frame is configured to move along a guide groove formed in the mirror box. Therefore, when the shaft is moved, high friction is likely to occur between the shaft and the guide groove. This high friction has been a cause of reducing the driving efficiency of the mirror driving device. On the other hand, in this embodiment, each axis | shaft 30-36 which comprises a four-bar linkage mechanism becomes a structure which moves without contacting other members. Therefore, friction does not occur when the shaft moves, in other words, when the mirror moves up and down. As a result, high driving efficiency can be obtained.

  In the present embodiment, the second arm 28 is driven by itself, and the first arm 26 is driven by the driving of the second arm 28. By moving the second arm 28 directly connected to the sub-mirror 20 (sub-mirror frame 22), the positional accuracy of the sub-mirror 20 can be further improved as compared to the case where the first arm 26 is moved.

  In the present embodiment, the second stopper 38 that restricts the lowering limit of the second arm 28 is provided in the vicinity of the lower end of the main mirror 16 when it is lowered. However, the second stopper 38 may naturally be provided at another position as long as the lower limit of the second arm 28 can be regulated. For example, it may be provided at position A in FIG. By providing the position A, the position accuracy of the sub mirror 20 can be further improved. That is, when the second stopper 38 is provided at the A position, the position of the second arm 28 is directly regulated by the second stopper 38. As a result, the positional accuracy of the upper end of the sub mirror 20 depends only on the positional accuracy of the third shaft 34, the fourth shaft 36, the second arm 28, and the second stopper 38. In other words, the positional accuracy of the upper end of the sub mirror 20 is not affected by the play of the first shaft 30, the second shaft 32, and the first arm 26. As a result, the position accuracy of the upper end of the sub mirror 20 can be improved more easily.

  Next, the opening / closing mechanism of the sub mirror 20 will be described with reference to FIGS. 7 to 9 are side views showing how the sub-mirror 20 is opened and closed, and show a lowered state, an intermediate state, and an upward state of the mirror, respectively. Note that in FIGS. 7 to 9, some members are not shown for easy viewing. 4 to 6 are right side views, while FIGS. 7 to 9 are left side views. Accordingly, the posture (inclination angle) of the sub mirror 20 in FIGS. 7 to 9 is symmetrical to the posture of the sub mirror 20 in FIGS.

  As described above, the sub mirror 20 is biased in the opening direction (the direction in which the angle with respect to the main mirror 16 increases) by the opening / closing torsion spring 50 inserted through the third shaft 34. Further, an eccentric pin 44 is connected to one end of the third shaft 34, and the angle of the eccentric pin 44 with respect to the sub mirror 20 is not changed. A protruding member 46 is formed at the tip of the eccentric pin 44, and this protruding member 46 is engaged with a cam groove 48 formed in the mirror box 24.

  In the mirror lowered state, the projection member 46 is positioned in the vicinity of the front side (photographing lens system side) end of the cam groove 48, and the projection member 46 and the cam groove 48 are in a positional relationship where they do not contact each other. . Accordingly, the sub mirror 20 receives only the urging force of the opening / closing torsion spring 50 and rotates (inclines) in the opening direction about the third shaft 34. This rotational movement is restricted by the lower end of the sub mirror frame 22 coming into contact with the third stopper 39. That is, the tilt angle of the sub mirror 20 is regulated by the third stopper 39 in the lowered state.

  When the mirror is raised, naturally, the third shaft 34 and the protruding member 46 of the eccentric pin 44 connected to the third shaft 34 are also raised. Here, the rising trajectory of the third axis 34 has an arc shape with the fourth axis 36 as the center. On the other hand, the rising locus of the protruding member 46 depends on the shape of the cam groove 48. The cam groove 48 has a substantially arc shape in which the inclination angle becomes gentle as the position thereof is increased, and the substantially arc shape intersects the movement locus of the third shaft 34. In other words, the cam groove 48 has a shape in which the height of its upper end surface gradually increases as it approaches the back side (imaging element side) from the front side (shooting lens system side).

  When the eccentric pin 44 rises while maintaining the tilt angle by raising the mirror, the protruding member 46 comes into contact with the end face of the cam groove 48. As the height of the protruding member 46 in contact with the cam groove 48 increases, the protruding member 46 moves to the back side according to the end face shape of the cam groove 48. On the other hand, the locking shaft moves while drawing an arcuate locus centering on the fourth axis 36 that is the same as the movement locus of the third shaft 34. In other words, the movement trajectory of the third shaft 34 becomes a substantially arc shape that moves to the front side as it increases. That is, as the position of the eccentric pin 44 increases as the mirror is raised, one end of the eccentric pin 44 moves rapidly to the front side and the other end moves rapidly to the back side. As a result, the long axis angle of the eccentric pin 44 gradually becomes gentle (substantially parallel to the optical axis of the photographing lens system) as the mirror is raised. Since the angle between the sub-mirror 20 and the eccentric pin 44 is not changed, the sub-mirror 20 similarly changes in angle as the angle of the eccentric pin 44 changes. As a result, the sub-mirror 20 gradually rotates in the closing direction (the direction in which the angle with the main mirror 16 is reduced) about the third axis 34 by raising the mirror. Thereby, the closing operation of the sub mirror 20 interlocked with the raising of the mirror is realized.

  In other words, in the present embodiment, a member whose angle with respect to the sub mirror 20 is not changed (the eccentric pin 44 and the protruding member 46), and a cam groove 48 having a shape that restricts the movement path by contacting the member whose angle is not changed. By providing, the sub mirror 20 closing operation is linked to the mirror raising operation. On the other hand, when the mirror is lowered, the sub mirror 20 receives the urging force of the opening / closing torsion spring 50 and gradually rotates in the opening direction. That is, the closing operation of the sub mirror 20 interlocked with the mirror lowering is realized by the opening / closing torsion spring 50. Thereby, both the mirror raising / lowering operation and the sub-mirror 20 opening / closing operation can be realized with a simpler configuration.

  Here, in the present embodiment, the rotation axis of the sub mirror 20 in the opening / closing operation of the sub mirror 20 is the third axis 34. That is, in the present embodiment, the rotation axis of the sub mirror 20 and the axis of the four-bar linkage mechanism (third axis 34) are the same. As a result, the number of axes in the entire mirror driving device 10 can be reduced. By reducing the number of axes, costs associated with the reduction in the number of parts, and accuracy improvement due to the effect of backlash can be achieved. As a result, the sub mirror 20 can be driven more easily and with high accuracy. However, in some cases, the opening / closing rotation shaft of the sub mirror may be provided separately from the moving shaft (third shaft 34) of the four-bar linkage mechanism. Even in this case, since the shaft of the four-bar linkage mechanism is directly connected to the sub mirror 20, the positional accuracy of the sub mirror 20 can be sufficiently improved.

It is the perspective view which looked at the mirror drive device which is an embodiment of the present invention from the front side. It is the perspective view which looked at the mirror drive device from the back side. It is a side view of a mirror drive device. It is a side view of the mirror drive device in the lowered state It is a side view of the mirror drive device in the middle of ascent. It is a side view of the mirror drive device of a raise state. It is a side view of the mirror drive device of a submirror opened. It is a side view of the mirror drive device in the middle of movement of a sub mirror in the closing direction. It is a side view of the mirror drive device with a submirror closed.

Explanation of symbols

  10 mirror drive device, 16 main mirror, 18 main mirror frame, 20 sub mirror, 22 sub mirror frame, 24 mirror box, 26 first arm, 28 second arm, 30 first axis, 32 second axis, 34 third axis, 36 Fourth shaft, 37 First stopper, 38 Second stopper, 39 Third stopper, 40 Positioning torsion spring, 44 Eccentric pin, 46 Projection member, 48 Cam groove, 50 Opening / closing torsion spring

Claims (4)

A main mirror whose angle with respect to the optical axis of the photographic lens system is variable along with its up and down movement,
A sub-mirror connected to the back of the main mirror and capable of moving up and down in conjunction with the raising and lowering of the main mirror;
An arm that connects a first axis provided on the fixed member and a second axis connected to the upper end of the main mirror, the first arm being rotatable about the first axis;
A second arm that connects a fourth axis provided on the fixed member and a third axis connected to the middle part of the main mirror and the upper end of the sub-mirror, the second arm being rotatable about the fourth axis Arm,
With
A mirror driving device, wherein a main mirror and a sub mirror are moved up and down in conjunction with each other by rotating and driving the first arm and the second arm in conjunction with each other while maintaining the distance relationship between the second axis and the third axis. The mirror driving device according to claim 1,
The first arm is driven by the second arm. The mirror driving device according to claim 1 or 2,
A mirror driving device characterized in that the sub-mirror changes an angle with respect to the main mirror by rotating around the third axis in conjunction with the raising and lowering operation. The mirror driving device according to claim 3,
An elastic member that urges the sub mirror in a direction in which the angle with respect to the main mirror increases;
A rotation member whose angle with respect to the sub-mirror does not change and rotates around the third axis together with the sub-mirror,
An engaging member provided at one end of the rotating member;
A groove provided in the fixing member and engaged with the engaging member, the cam groove for restricting a moving path of the engaging member when the main mirror is lifted;
With
The moving path of the engaging member regulated by the cam groove is a path in which the rotating member is gradually inclined in the direction in which the sub mirror is in close contact with the main mirror as the main mirror is raised. apparatus.

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