JP2012042617A - Imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the focus accuracy of an shooting image by preventing the unevenness of focus detection accuracy due to rattling of a rotation shaft rotatably supporting a main mirror.SOLUTION: An imaging device comprises: a main mirror pivoted on a groove of a mirror box, and entering a first state going into a shooting optical path and a second state retracting from the shooting optical path; a sub mirror pivoted by the main mirror, and entering a first state reflecting a light flux passing through the main mirror and a second state retracting from the shooting optical path; and an energizing member for energizing a rotation shaft. A clearance is formed so as to make a rattling direction of the rotation shaft to the groove parallel with a reflecting surface direction of the sub mirror when the sub mirror is in the first state. The energizing member energizes the rotation shaft from a direction orthogonal to the reflecting surface direction of the sub mirror when the sub mirror is in the first state.

Description

  The present invention relates to an imaging apparatus such as a single-lens reflex camera, and more particularly to an improvement of a mirror mechanism provided in the imaging apparatus.

  FIG. 7 is a schematic view showing an example of a conventional mirror mechanism provided in a single-lens reflex camera or the like, and FIG. 8 is a detailed view of a portion F in FIG.

  As shown in FIG. 7, the mirror mechanism includes a main mirror 54 formed of a half mirror, and a sub mirror 53 that is rotatably supported with respect to the main mirror 54.

  The main mirror 54 is held by the receiving plate 50, and a rotating shaft 50 a is provided at the end of the receiving plate 50. The main mirror 54 is rotatably supported with respect to the mirror box by fitting the rotation shaft 50a into a U-shaped groove 1a (see FIG. 8) provided in a mirror box (not shown) in the camera body. The The rotating shaft 50a is urged toward the subject side substantially parallel to the optical axis by the leaf spring 48, thereby preventing rattling of the rotating shaft 50a in the optical axis direction in the U-shaped groove 1a. ing. The main mirror 54 enters the photographing optical path during the viewfinder observation (mirror down (FIG. 7)) and retreats from the photographing optical path during the photographing (mirror up) by the pivoting operation about the pivot shaft 50a.

  The sub mirror 53 is held by a receiving plate 51, and an end portion of the receiving plate 51 is rotatably supported on the back side (image surface side) of the main mirror 54 in a mirror-down state via a rotating shaft 50c. The The receiving plate 51 is in contact with the positioning member 52 in a state of being biased counterclockwise in FIG. 7 (arrow G direction) by a torsion spring (not shown).

  The subject light that has passed through the photographing lens (not shown) is divided into light that is reflected upward by the main mirror 54 and light that is transmitted through the main mirror 54, and the light reflected upward by the main mirror 54 is the pentagon (not shown). It is guided to a finder (not shown) through a prism. The light transmitted through the main mirror 54 is reflected by the sub-mirror 53 and guided to the focus detection device 56 disposed below, thereby enabling TTL phase difference AF (Patent Document 1).

JP-A-5-11340

  By the way, in Patent Document 1, the rotation shaft 50a provided at the end of the receiving plate 50 of the main mirror 54 is fitted into the U-shaped groove 1a provided in the mirror box 1, and the optical axis is provided by the leaf spring 48. Is biased to the subject side substantially in parallel. However, since the rotation shaft 50a is fitted with a gap with respect to the U-shaped groove 1a so that the main mirror 54 can rotate smoothly, as shown in FIG. Shaking occurs in the direction I orthogonal to the direction H.

  In this case, for example, as shown in FIG. 9, if the position of the rotation shaft 50 a rattles downward (in the direction of arrow I), the position of the rotation shaft 50 c of the sub mirror 53 also changes accordingly. At this time, since the position where the receiving plate 51 of the sub mirror 53 contacts the positioning member 52 does not change, the angle of the reflecting surface of the sub mirror 53 with respect to the optical axis changes, and the directing direction of the light 70 with respect to the focus detection device 56 shifts. . Since the direction of rattling of the rotation shaft 50a may change every time the user operates the release button and performs a shooting operation, the focus detection accuracy varies, and the focus accuracy of the captured image decreases. There is a problem of doing.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve focus accuracy of a captured image by preventing variation in focus detection accuracy due to shakiness of a rotation shaft that rotatably supports a first mirror member. And

  In order to achieve the above object, an imaging apparatus according to the present invention includes a mirror box in which a groove is formed, and a rotation shaft that is pivotally supported by the groove and rotates with respect to the mirror box. A first mirror member that enters a first state and a second state that retreats from the imaging optical path, and is pivotally supported by the first mirror member and enters the imaging optical path to enter the first mirror. A first state in which the light beam transmitted through the member is reflected, a second mirror member that is integrated with the first mirror member and in a second state in which the light is retreated from the photographing optical path, and the shaft that is pivotally supported by the groove An urging member that urges the rotation shaft, and the direction of the rotation of the rotation shaft with respect to the groove is such that the second mirror member is in the first state when the second mirror member is in the first state. Between the groove and the pivot shaft so as to be parallel to the reflection surface direction of the member A gap is formed, and the urging member urges the rotating shaft from a direction orthogonal to the reflecting surface direction of the second mirror member when the second mirror member is in the first state. It is characterized by that.

  According to the present invention, it is possible to prevent variation in focus detection accuracy due to the shakiness of the rotation shaft that rotatably supports the first mirror member, so that the accuracy of focusing the captured image can be improved. Can be planned.

It is principal part sectional drawing of the single-lens reflex camera which is an example of embodiment of the imaging device of this invention. It is a figure which shows the mirror down state of a mirror mechanism. It is the figure which looked at the mirror mechanism shown in FIG. 2 from the back side. It is a figure which shows typically the mirror mechanism in a mirror down state. It is the B section detailed drawing of FIG. It is a schematic diagram of a mirror mechanism showing a state in which the rotation axis of the main mirror changes its position in the −D direction due to rattling in the U-shaped groove of the mirror box. It is a schematic diagram which shows an example of the conventional mirror mechanism provided in a single-lens reflex camera. FIG. 8 is a detailed view of a part F in FIG. 7. It is a schematic diagram for demonstrating the state of a mirror mechanism when the rotation axis of a main mirror rattles downward and a position changes.

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

  1 is a cross-sectional view of a main part of a single-lens reflex camera as an example of an embodiment of an imaging apparatus of the present invention, FIG. 2 is a diagram showing a mirror-down state of the mirror mechanism, and FIG. 3 is a diagram showing the mirror mechanism shown in FIG. FIG.

  As shown in FIGS. 1 and 2, the single-lens reflex camera of the present embodiment is in a first state (mirror down state) that enters the imaging optical path during viewfinder observation, and retracts from the imaging optical path during imaging. The mirror mechanism 10 that is in the state (mirror up state) is provided. The mirror mechanism 10 includes a main mirror 154 composed of a half mirror, and a sub mirror 153 supported so as to be rotatable with respect to the main mirror 154.

  The main mirror 154 is held by the receiving plate 150, and a rotating shaft 150 a is integrally provided at the end of the receiving plate 150. A pivot shaft 150a is pivotally supported by a U-shaped groove 101a provided in the mirror box 101, so that the main mirror 154 is supported so as to be pivotable between the mirror down position and the mirror up position with respect to the mirror box 101. Is done. Here, the main mirror 154 and the receiving plate 150 correspond to an example of the first mirror member of the present invention, and the U-shaped groove 101a corresponds to an example of the groove of the present invention.

  The sub mirror 153 is pivotally supported by the receiving plate 151, and the end of the receiving plate 151 is rotated to the back side (image surface side) of the receiving plate 150 of the main mirror 154 in the mirror-down state via the rotation shaft 150c. It is supported movably. As shown in FIG. 3, the receiving plate 151 is in contact with the eccentric dowel 152 in a state of being biased in the opening direction A (counterclockwise direction in FIG. 2) with respect to the main mirror 154 by the torsion spring 157. It is positioned at a position that forms a predetermined angle with respect to the mirror 154. Further, the reflecting surface of the sub mirror 153 is arranged so as to be parallel to the surface of the receiving plate 151 that contacts the eccentric dowel 152. Here, the sub mirror 153 and the receiving plate 151 correspond to an example of the second mirror member of the present invention.

  In a state where the receiving plate 151 of the sub-mirror 153 is in contact with the eccentric dowel 152, the end of the receiving plate 151 opposite to the end of contact with the eccentric dowel 152 with the rotation shaft 150c interposed therebetween is the mirror box 101. The pin 155 is fixed so as not to come into contact with the pin 155. For this reason, by rotating the eccentric dowel 152 about the eccentric shaft 152a, the receiving plate 151 of the sub mirror 153 rotates slightly about the rotation shaft 150c, and thereby the sub mirror 153 with respect to the main mirror 154 in the mirror down state. Can be adjusted.

  The subject light that has entered the photographing optical path through a photographing lens (not shown) is divided into light that is reflected upward by the main mirror 154 and light that is transmitted through the main mirror 154, and the light reflected upward by the main mirror 154 is Then, it is led to the viewfinder through the pentaprism PP. Further, the light beam transmitted through the main mirror 154 is reflected by the sub mirror 153 and enters a TTL phase difference AF unit 156 as a focus detection device disposed below.

  4 is a diagram schematically showing a mirror mechanism in a mirror-down state, and FIG. 5 is a detailed view of a portion B in FIG.

  As described above, the rotating shaft 150a provided at the end of the receiving plate 150 of the main mirror 154 is pivotally supported by the U-shaped groove 101a of the mirror box 101, but the rotating shaft 150a is smoothly rotated. Needs to provide a gap between the rotation shaft 150a and the U-shaped groove 101a. That is, it is necessary to make the diameter of the U-shaped groove 101a larger than the diameter of the rotating shaft 150a, and rattling occurs in the rotating shaft 150a in the U-shaped groove 101a.

  Here, in the present embodiment, as shown in FIGS. 4 and 5, the direction ± D of the backlash of the rotation shaft 150 a is such that the receiving plate 151 is in contact with the eccentric dowel 152. A U-shaped groove 101a is formed so as to be parallel to the reflecting surface direction. That is, the direction of rattling of the rotation shaft 150a is parallel to the direction of the reflecting surface of the sub mirror 153 when the sub mirror 153 is in the first state. Further, the leaf spring 148 is formed with an urging surface 148 a parallel to the reflecting surface direction of the sub mirror 153 in a state where the receiving plate 151 is in contact with the eccentric dowel 152. Then, the rotating shaft 150 a fitted in the U-shaped groove 101 a is biased in the direction C perpendicular to the reflecting surface of the sub mirror 153 by the biasing surface 148 a of the leaf spring 148. Therefore, each time the mirror mechanism 10 rotates between the mirror down position (first state) and the mirror up position (second state), the rotation shaft 150a follows the rattling direction ± D. It moves to the position 150a1 and the position 150a2 in FIG. Here, the leaf spring 148 corresponds to an example of the biasing member of the present invention.

  FIG. 6 is a schematic diagram of the mirror mechanism showing a state in which the position of the rotation shaft 150a is changed in the −D direction due to rattling in the U-shaped groove 101a.

  As shown in FIG. 6, when the rotation shaft 150a rattles in the -D direction within the U-shaped groove 101a and changes its position, the rotation shaft 150c also changes its position in the same direction. Further, the receiving plate 151 of the sub mirror 153 is in contact with the eccentric dowel 152 while being urged counterclockwise in FIG. 6 by the torsion spring 157.

  Here, since the reflecting surface of the sub mirror 153, the surface 151a of the receiving plate 151 of the sub mirror 153 that contacts the eccentric dowel 152, and the changing direction -D of the rotating shaft 150c are all parallel, the reflecting surface of the sub mirror 153 is It moves only in the plane. Therefore, before and after the position of the rotation shaft 150a changes to the shading direction ± D, the directivity direction of the light reflected by the sub mirror 153 with respect to the TTL phase difference AF unit 156 is the same.

  As described above, in this embodiment, every time the mirror mechanism 10 rotates, the TTL phase difference AF of the light reflected by the sub-mirror 153 even if the rotation shaft 150a moves in the rattling direction ± D. The directivity direction with respect to the unit 156 does not change. As a result, it is possible to prevent variations in focus detection accuracy due to rattling of the rotation shaft 150a that rotatably supports the receiving plate 150 of the main mirror 154, and to improve the focusing accuracy of the captured image. Can do.

  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.

148 Leaf spring 150 Receiving plate 150a Rotating shaft 150c Rotating shaft 151 Receiving plate 152 Eccentric dowel 153 Sub mirror 154 Main mirror 156 TTL phase difference AF unit 157 Torsion spring

Claims (2)

A mirror box in which a groove is formed;
A first mirror member that is pivotally supported by the groove and rotates with respect to the mirror box to enter a first state that enters the imaging optical path and a second state that retreats from the imaging optical path. When,
An imaging optical path integrated with the first mirror member and a first state that is pivotally supported by the first mirror member, reflects the light beam that has entered the imaging optical path and has passed through the first mirror member. A second mirror member that is in a second state of being retracted from
An urging member that urges the rotating shaft pivotally supported by the groove;
The direction of rattling of the pivot shaft with respect to the groove is parallel to the reflective surface direction of the second mirror member when the second mirror member is in the first state. Forming a gap between the groove and the pivot shaft;
The urging member urges the rotation shaft from a direction orthogonal to a reflecting surface direction of the second mirror member when the second mirror member is in the first state. Imaging device.   The urging member is a leaf spring in which an urging surface that is parallel to a reflecting surface direction of the second mirror member when the second mirror member is in the first state is formed. The imaging apparatus according to claim 1, wherein the rotation shaft is biased by a biasing surface.

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