JP2012042860A - Image pickup apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration in location accuracy in a mirror-down state of a mirror unit by suppressing the inclination of the axial direction of a balancer lever which holds the mirror unit turned into the mirror-down state with a receiving shaft.SOLUTION: A single-lens reflex camera includes: a holding member 410 disposed at one side in a rotational shaft direction of a mirror unit 310; a balancer lever 420 rotationally supported by the holding member 410 on a surface which is an opposite side of a surface of the holding member 410 facing the mirror unit 310 and having a receiving shaft 440 with which the mirror unit 310 rotationally turned from a mirror-up state to the mirror-down state collides; and a spring member energizing the balancer lever 420 in a direction opposite to the direction where the mirror unit 310 collides with the receiving shaft 440. The balancer lever 420 is formed with a butting part 421 adapted to butt on the holding member 410 in the axial direction of a support shaft 430 when the mirror unit 310 collides with the receiving shaft 440.

Description

  The present invention relates to an imaging apparatus such as a single-lens reflex camera provided with a mirror unit that advances and retreats a photographing optical path.

  An imaging apparatus such as a single-lens reflex camera has been proposed in which a balancer lever having a receiving shaft with which a mirror unit collides is supported rotatably on a holding member fixed to a mirror box by a support shaft (Patent Document 1). ).

  In this proposal, the mirror unit entering the photographing optical path is caused to collide with the receiving shaft of the balancer lever, and the balancer lever is rotated about the support shaft against the urging force of the spring. Thereby, the kinetic energy of the mirror unit is attenuated to reduce the bounce of the mirror unit.

JP 2000-131755 A

  In Patent Document 1, the mirror unit collides with the bearing shaft of the balancer lever, and the balancer lever rotates against the urging force of the spring, so that the kinetic energy transmitted from the mirror unit to the balancer lever is released. . Then, after opening, the balancer lever returns to its original position by the biasing force of the spring while holding the mirror unit by the receiving shaft.

  Since the balancer lever is supported by the holding member on the mirror unit side, and the receiving shaft is formed so as to protrude from the support shaft of the balancer lever, the force input from the mirror unit to the receiving shaft is the balancer with the support shaft as a fulcrum. Acts like twisting the lever.

  In addition, since a slight gap is provided between the support shaft and the balancer lever in the axial direction, the balance between the balancer lever and the force acting to twist the balancer lever is caused by this gap. The balancer lever tilts in the axial direction.

  When the mirror unit enters the photographing optical path, the position of the mirror unit is determined by the bearing shaft of the balancer lever. Therefore, the position accuracy of the mirror unit that has entered the photographing optical path is lowered by tilting the balancer lever in the axial direction. End up.

  Accordingly, an object of the present invention is to prevent the positional accuracy of the mirror unit from being lowered in the mirror-down state by suppressing the tilt in the axial direction of the balancer member that holds the mirror unit in the mirror-down state by the receiving shaft. .

  In order to achieve the above object, an imaging apparatus according to the present invention includes a mirror unit that rotates between a mirror-down state and a mirror-up state, and a holding member that is disposed on one side of the rotation axis direction of the mirror unit. And the mirror unit that is pivotally supported by the holding member on a surface opposite to the surface facing the mirror unit of the holding member, and collides with the mirror unit rotated from the mirror-up state to the mirror-down state A balancer member having a receiving shaft, and a spring member that urges the balancer member in a direction opposite to a direction in which the mirror unit collides with the receiving shaft, and the mirror unit includes the receiving member. An abutting portion that abuts against the holding member in the axial direction of the support shaft when colliding with the shaft is formed.

  According to the present invention, since the inclination of the balancer member holding the mirror unit in the mirror-down state with the receiving shaft can be suppressed, it is possible to prevent the positional accuracy of the mirror unit from being lowered in the mirror-down state. .

1 is a diagram illustrating a schematic configuration of a single-lens reflex camera that is an example of an embodiment of an imaging apparatus of the present invention. FIG. It is a perspective view for demonstrating the bounce prevention mechanism for preventing the bounce of the main mirror of a mirror unit. It is a perspective view for demonstrating the bounce prevention mechanism for preventing the bounce of the submirror of a mirror unit. It is a figure which shows the state of the bounce prevention mechanism of the main mirror when the mirror unit is mirroring up at the time of imaging | photography. It is a figure which shows the state which the mirror unit approached into the imaging | photography optical path and the holder of the main mirror collided with the receiving shaft of the balancer lever. It is a figure which shows the state which the balancer lever rotated against the urging | biasing force of the return spring centering on the support shaft. It is a figure which shows typically the bounce prevention mechanism shown in FIG. It is a figure which shows the conventional bounce prevention mechanism typically.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of a single-lens reflex camera which is an example of an embodiment of an imaging apparatus of the present invention.

  As shown in FIG. 1, the single-lens reflex camera of this embodiment includes a camera body 100 and a lens unit 200 that is replaceably attached to the camera body.

  The lens unit 200 is provided with a photographing lens group 202, a diaphragm 203, a microprocessor 201 that controls various operations of the lens unit 200, and the like. The microprocessor 201 can communicate with a microprocessor 112 provided in the camera body 100 via a communication contact.

  On the other hand, the camera body 100 is provided with a mirror box 120, and the mirror box 120 is provided with a mirror unit 300 and a bounce prevention mechanism 400.

  The mirror unit 300 is rotatably supported by the mirror box 120 and includes a main mirror 104 formed of a half mirror and a sub mirror 105 that is rotatably supported with respect to the main mirror 104. The mirror unit 300 is in a mirror-down state that enters the imaging optical path during viewfinder observation, and is in a mirror-up state in which the mirror unit 300 is retracted from the imaging optical path during imaging due to the rotation operation.

  When the mirror unit 300 is in the mirror-down state, the luminous flux of the subject that has entered the imaging optical path through the lens unit 200 is divided into a luminous flux that is reflected upward by the main mirror 104 and a luminous flux that is transmitted through the main mirror 104.

  The light beam reflected upward by the main mirror 104 is guided to the eyepiece lens 102 through the finder screen 103, the finder display unit 115, and the pentaprism 101, and is also guided to the photometric sensor 110 through the photometric lens 111. The light beam transmitted through the main mirror 104 is reflected by the sub mirror 105 and enters a TTL phase difference AF unit 109 serving as a focus detection device disposed below.

  On the other hand, when the mirror unit 300 is in the mirror-up state, the light beam of the subject that has entered the imaging optical path through the lens unit 200 passes through the focal plane shutter 107 and the low-pass filter 117 and forms an image on the image sensor 106. The image formed on the image sensor 106 is displayed on a display device 116 provided on the back surface of the camera body 100.

  Next, the bounce prevention mechanisms 400 and 500 will be described with reference to FIGS.

  FIG. 2 is a perspective view for explaining a bounce prevention mechanism 400 for preventing the main mirror 104 of the mirror unit 300 from bouncing.

  As shown in FIG. 2, the bounce prevention mechanism 400 includes a holding member 410 attached to the mirror box 120.

  The holding member 410 is attached to the mirror box 120 with a screw or the like on one side in the rotational axis direction of the mirror unit 300 that is in the mirror down state, and bends and protrudes from the attachment portion 410a to the mirror unit 300 side. Lever support portion 410b. A balancer lever 420 is rotatably supported via a support shaft 430 on the surface of the lever support portion 410b opposite to the mirror unit 300. That is, the balancer lever 420 is rotatably supported by the holding member 410 on the surface opposite to the surface facing the mirror unit 300 of the holding member 410.

  The balancer lever 420 is provided with a receiving shaft 440 that collides with the holder 310 of the main mirror 104 when the mirror unit 300 is in the mirror-down state, extending substantially parallel to the rotating shaft of the holder 310. Here, the balancer lever 420 corresponds to an example of a balancer member of the present invention.

  When the holder 310 of the main mirror 104 collides with the receiving shaft 440, the balancer lever 420 rotates about the support shaft 430 in the clockwise direction in the figure. At this time, the abutting portion 421 positioned above the support shaft 430 of the balancer lever 420 abuts against the lever support portion 410b of the holding member 410 in the axial direction of the support shaft 430. Here, in the present embodiment, the receiving shaft 440 is disposed between the abutting portion 421 and the support shaft 430. When the balancer lever 420 rotates around the support shaft 430, the abutting portion 421 comes into contact with the surface of the holding member 410 orthogonal to the support shaft 430 to prevent the balancer lever 420 from tilting. You may form in any part of the lever 420. FIG.

  Further, a return spring 450 that urges the balancer lever 420 in a direction opposite to the direction in which the holder 310 collides with the receiving shaft 440 is stretched between the tip of the balancer lever 420 and the mirror box 120. Therefore, when the balancer lever 420 rotates about the support shaft 430 in the clockwise direction in the drawing, the balancer lever 420 rotates against the urging force of the return spring 450.

  The holding member 410 is provided with a stopper member 460 for restricting the amount of rotation of the balancer lever 420 in the clockwise direction in the drawing.

  In addition, after the holder 310 collides with the receiving shaft 440 and the kinetic energy of the mirror unit 300 is released, the balancer lever 420 is rotated counterclockwise in the figure by the urging force of the return spring 450 to stop the stopper 422. (See FIG. 4) and return to the initial position.

  Here, in the receiving shaft 440 and the supporting shaft 430, the line connecting the center of the receiving shaft 440 and the center of the supporting shaft 430 indicates the center of the rotating shaft of the holder 310 and the position where the holder 310 collides with the receiving shaft 440. It arrange | positions so that it may become substantially parallel with the line to connect.

  By arranging in this way, the kinetic energy of the mirror unit 300 when the mirror is down can be efficiently transmitted to the receiving shaft 440 of the balancer lever 420.

  Further, the bounce prevention mechanism 400 has an angle adjustment function for adjusting the angle of the main mirror 104. That is, the angle of the main mirror 104 relative to the mirror box 120 can be adjusted by rotating the holding member 410 about the adjustment reference hole 411 and adjusting the angle of the holder 310 to fix the mounting portion 410a to the mirror box 120. It becomes possible.

  FIG. 3 is a perspective view for explaining a bounce prevention mechanism 500 for preventing the sub mirror 105 of the mirror unit 300 from bouncing.

  The bounce prevention mechanism 500 is disposed on the opposite side of the bounce prevention mechanism 400 with the mirror unit 300 interposed therebetween, and includes a holding member 510 attached to the mirror box 120.

  The holding member 510 is provided with an adjustment reference hole 511 substantially coaxially with the rotation axis of the holder 320 of the sub mirror 105. The adjustment member 511 is rotated about the adjustment reference hole 511 to adjust the angle of the sub mirror 105 and then held. The member 510 is fixed to the mirror box 120.

  In addition, a bounce prevention lever 520 is rotatably supported via a support shaft 530 and a positioning shaft 540 for positioning the holder 320 is fixed to the holding member 510. By bringing the holder 320 into contact with the positioning shaft 540 when the mirror of the mirror unit 300 is lowered, the angle of the sub mirror 105 is guaranteed.

  A bounce prevention shaft 550 that prevents the holder 320 from bouncing is fixed to the bounce prevention lever 520, and a bounce prevention groove 321 provided in the holder 320 is caught by the bounce prevention shaft 550 when the mirror unit 300 is mirror-down. It has become.

  A biasing spring 560 is stretched between the holding member 510 and the bounce prevention lever 520. When the mirror unit 300 starts mirror down, the bounce prevention shaft 550 traces the cam surface 322 of the holder 320, so that the bounce prevention lever 520 rotates against the biasing spring 560. When the mirror unit 300 is in the mirror down state, the bounce prevention shaft 550 enters the bounce prevention groove 321. Since the bounce prevention shaft 550 and the bounce prevention groove 321 are engaged, the bounce prevention lever 520 is rotated when the holder 320 bounces. The bounce prevention lever 520 is rotated by the biasing spring 560. Rotation is limited. Thereby, the bounce of the holder 320 is reduced.

  Since the bounce prevention shaft 550 is a shaft for reducing the bounce of the holder 320, the bounce prevention shaft 550 does not come into contact with the holder 320 after the angle of the sub mirror 105 is stabilized.

  Next, an example of the operation of the bounce prevention mechanism 400 will be described with reference to FIGS.

  FIG. 4 is a diagram illustrating a state of the bounce prevention mechanism 400 when the mirror unit 300 is mirror-up during shooting.

  In the state shown in FIG. 4, the balancer lever 420 is disposed at the initial position in contact with the stopper 422 of the holding member 410 while being urged counterclockwise by the return spring 450.

  When the photographing is finished, as shown in FIG. 5, the mirror unit 300 enters the photographing optical path and enters the mirror down state, and the holder 310 of the main mirror 104 of the mirror unit 300 collides with the receiving shaft 440 of the balancer lever 420. To do. Thereby, the kinetic energy of the mirror unit 300 is transmitted to the balancer lever 420 and the kinetic energy is attenuated, and the mirror unit 300 is bounced back to the receiving shaft 440 to reduce the bounce.

  As shown in FIG. 6, the balancer lever 420 to which the kinetic energy is transmitted from the mirror unit 300 rotates around the support shaft 430 in the clockwise direction against the urging force of the return spring 450 and rotates. Sometimes the kinetic energy transmitted from the mirror unit 300 is released.

  When the kinetic energy is released, the balancer lever 420 is rotated counterclockwise in the figure by the urging force of the return spring 450 in a state where the holder 310 is in contact with the receiving shaft 440 and is in contact with the stopper 422 to be initial. Return to position (FIG. 5).

  In a state where the holder 310 is in contact with the receiving shaft 440, a force from the holder 310 is applied to the receiving shaft 440, and this force causes a twist about the support shaft 430 as a fulcrum with respect to the balancer lever 420. generate.

  In addition, a slight gap is provided between the support shaft 430 and the balancer lever 420 in the axial direction in order to ensure smooth rotation of the balancer lever 420. For this reason, the balancer lever 420 is tilted in the axial direction due to the backlash in the axial direction of the balancer lever 420 due to the gap and the aforementioned twisting force acting on the balancer lever 420.

  Here, in this embodiment, the abutting portion 421 of the balancer lever 420 is abutted against the lever support portion 410b of the holding member 410 in the axial direction of the support shaft 430, thereby suppressing the inclination of the balancer lever 420 in the axial direction. is doing.

  Hereinafter, this point will be described in detail with reference to FIGS.

  FIG. 7 is a diagram schematically showing the bounce prevention mechanism 400 shown in FIG. 2 used in the single-lens reflex camera of this embodiment, and FIG. 8 is a diagram schematically showing a conventional bounce prevention mechanism.

  In FIG. 8, the parts corresponding to the bound mechanism 400 of the present embodiment are denoted by the same reference numerals. In FIG. 7, the balancer lever 420 is disposed on the side opposite to the mirror unit 300 of the holding member 410, whereas in FIG. 8, the balancer lever 420 is disposed on the mirror unit 300 side of the holding member 410. The point is different.

  First, in FIG. 7, the balancer lever 420 has a backlash AA with respect to the holding member 410 and is supported by the support shaft 430, and the holder 310 comes into contact with the receiving shaft 440, so that the balancer lever 420 has a backlash. A tilt in the axial direction corresponding to the amount AA is generated.

  At this time, since the abutting portion 421 on the upper end side of the balancer lever 420 abuts against the holding member 410 in the axial direction, the receiving shaft 440 moves by the movement amount AB.

  On the other hand, in FIG. 8, the balancer lever 420 has a backlash amount BA with respect to the holding member 410 and is supported by the support shaft 430, and the holder 310 comes into contact with the receiving shaft 440, thereby An inclination in the axial direction corresponding to the amount BA occurs.

  At this time, since the abutting portion 421 on the lower end side of the balancer lever 420 abuts against the holding member 410 in the axial direction, the receiving shaft 440 moves by the movement amount BB.

  Here, the distance between the support shaft 430 and the abutting portion 421 in FIG. 7 is AC, and the distance between the support shaft 430 and the receiving shaft 440 is AD. Further, when the distance between the support shaft 430 and the abutting portion 421 in FIG. 8 is BC and the distance between the support shaft 430 and the receiving shaft 440 is BD, AB: AA = AC−AD: AC, BB: BA = BC + BD : BC relationship.

  Therefore, AB = (AA × (AC−AD)) / AC, BB = (BA × (BC + BD)) / BC, and when the distance AC is equal to the distance BC and the backlash amount AA is equal to the backlash amount BA, BB = (AA × (AC + BD)) / AC. Therefore, AB−BB = − (AD + BD) / AC <0, and the distance AB is smaller than the distance BB. From this, it can be seen that the axial inclination of the balancer lever 420 in FIG. 7 is smaller than the axial inclination of the balancer lever 420 in FIG.

As for the inclination of the receiving shaft 440, θa = tan ⁻¹ ((AA−AB) /) where θa is the inclination generated in the receiving shaft 440 in FIG. 7 and θb is the inclination generated in the receiving shaft 440 in FIG. AC), θb = tan ⁻¹ (BA / BC).

Here, when the distance AC and the distance BC are equal, and the backlash amount AA and the backlash amount BA are equal, θb = tan ⁻¹ (AA / AC), and thus the relationship θa <θb is established. Accordingly, it can be seen that the inclination of the receiving shaft 440 in FIG. 7 is smaller than the inclination of the receiving shaft 440 in FIG.

  As described above, in the present embodiment, the balancer lever 420 is rotatably disposed on the holding member 410 on the opposite side of the mirror unit 300, and the abutting portion 421 of the balancer lever 420 is axial with respect to the holding member 410. I try to hit it. Thereby, the inclination of the balancer lever 420 that holds the main mirror 104 of the mirror unit 300 that has entered the photographing optical path can be suppressed, and the posture of the mirror unit 300 can be stabilized.

  The configuration of the present invention is not limited to that exemplified in the above embodiment, and the material, shape, dimensions, form, number, arrangement location, and the like can be changed as appropriate without departing from the scope of the present invention. It is.

104 Main mirror 105 Sub mirror 300 Mirror unit 400 Bound prevention mechanism 410 Holding member 420 Balancer lever 421 Abutting portion 430 Support shaft 440 Receiving shaft 450 Return spring

Claims (3)

A mirror unit that rotates between a mirror-down state and a mirror-up state;
A holding member disposed on one side of the rotation axis direction of the mirror unit;
A receiving member that is supported rotatably on the holding member on a surface opposite to the surface facing the mirror unit of the holding member, and the mirror unit rotated from the mirror-up state to the mirror-down state collides. A balancer member having a shaft;
A spring member that urges the balancer member in a direction opposite to the direction in which the mirror unit collides with the receiving shaft,
The image pickup apparatus, wherein the balancer member is formed with an abutting portion that abuts against the holding member in an axial direction of the support shaft when the mirror unit collides with the receiving shaft.   The imaging apparatus according to claim 1, wherein the receiving shaft is disposed between the support shaft and the abutting portion.   In the receiving shaft and the supporting shaft, a line connecting the center of the receiving shaft and the center of the supporting shaft connects the center of the rotating shaft of the mirror unit and the position where the mirror unit collides with the receiving shaft. The imaging apparatus according to claim 1, wherein the imaging apparatus is arranged so as to be parallel to the line.

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