JP2010026002A - Digital camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital camera capable of promptly suppressing residual vibration of a sub mirror supported by a main mirror (quick return mirror). <P>SOLUTION: A single lens reflex camera that is the digital camera includes: a mirror frame 15 including the quick return mirror 16 reciprocating between an advancing position P1 where it guides a part of subject luminous flux from a photographic lens 3a to a finder unit 9 and a retracting position P2 where it makes the subject luminous flux from the photographic lens 3a incident on an image sensor; a stopper 4a regulating a stop position at the advancing position P1 of the mirror frame 15; a sub mirror frame 17 including the sub mirror 17a guiding a part of the subject luminous flux from the photographic lens 3a transmitted through the quick return mirror 16 to a range-finding sensor 6 when the mirror frame 15 stops at the advancing position P1; and a turning frame 21 for supporting the sub mirror frame 17 arranged at an almost node position S0 of the vibration of the mirror frame 17. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a digital camera provided with a mirror mechanism for driving a distance measuring sub-mirror.

  Conventionally, in a digital camera equipped with a main mirror (quick return mirror) for viewfinder observation (including distance measurement), for example, a digital single-lens reflex camera, the main mirror equipped with a distance measurement sub-mirror is driven to rotate to shoot. To enter the optical path of the subject luminous flux captured via the taking lens, which is an optical system, to reflect the subject luminous flux to the viewfinder unit for finder observation, and to measure the subject distance (ranging) with the sub mirror It moves to an approach position where the subject light beam is reflected toward the distance measuring sensor and a retreat position where the subject light beam is retracted from the optical path of the subject light beam and can enter the image sensor to obtain an image signal of the subject image.

  FIG. 5 is a schematic diagram showing the configuration of the main part around the main mirror of the conventional single-lens reflex camera. In the camera, the subject luminous flux along the optical axis O taken from the photographing lens is the optical axis O. Are taken into the camera body 100. On the optical axis O, a sub-mirror 102 supported by a support shaft 104, a rotatable main mirror 101 supported by a rotating shaft 103, and an imaging unit 107 including an imaging element are arranged. A finder unit 108 having a screen, a pentaprism, an eyepiece and the like is disposed on the upper portion of 101.

  As shown in FIG. 5, the main mirror 101 is rotationally driven to an entry position P 1 that contacts the stopper 105 and a retracted position P 2 that contacts the stopper 106 via a drive lever (not shown) of the mirror drive mechanism. However, the spring is normally biased toward the entry position P1, and the retraction position P2 is rotationally driven in a state where the biasing spring is charged by the cam. The entry position P1 is rotationally driven at a high speed by the urging force of the urging spring as the cam moves backward. Therefore, when it is rotationally driven to the entry position P1 and abuts against the stopper 105, a bounce in the rotational direction occurs. It takes time until the viewfinder observation image is stabilized due to the occurrence of the bounce. In addition, it is necessary to perform distance measurement by the sub mirror after the bound is stabilized.

  Therefore, the mirror bounce prevention device of the camera disclosed in Patent Document 1 has a surface to be applied to the mirror stopper, and the corresponding attachment surface is inclined with respect to the circumference of the rotation direction of the mirror, and It is formed along a plane perpendicular to the optical axis of the taking lens. When the mirror is brought into contact with the stopper, the mirror vibrates in a state in which the inclination with respect to the optical axis of the photographing lens does not change, thereby suppressing fluctuation of the finder observation image due to the vibration.

  The mirror bounce prevention devices disclosed in Patent Documents 2 to 5 are provided with a bounce prevention member for forcibly pressing the mirror toward the stopper when the mirror abuts against the stopper.

  In the mirror bounce prevention devices disclosed in Patent Documents 6 to 9, when the mirror comes into contact with the stopper, the kinetic energy at the time of mirror rotation is applied to the movable inertia by applying the mirror to a movable inertia body provided separately. It is constructed to absorb the body and eliminate the bounce on the mirror side.

Further, in the quick return mirror device disclosed in Patent Document 10, the vibration of the quick return mirror is provided by disposing a vibration damping layer made of a vibration damping material between the quick return mirror and a mirror holder that holds the mirror. It is intended to suppress.
JP-A 61-278831 Japanese Patent Laid-Open No. 10-206968 JP-A-11-024163 Japanese Patent Laid-Open No. 11-038501 Japanese Patent No. 3900551 JP 09-274249 A Japanese Patent No. 3453799 Japanese Patent No. 3536131 Japanese Patent No. 3804109 JP 2006-189539 A

  However, although the mirror bound prevention device disclosed in Patent Document 1 described above is simple in configuration, it is not always effective for quickly accommodating the mirror bound.

  In the above-described patent documents 2 to 5, the structure of the bounce prevention member is complicated, the area occupied by the mirror portion is increased, and it is difficult to reduce the size of the apparatus.

  The mirror bounce prevention devices disclosed in Patent Documents 6 to 9 require a movable inertial body that is separate from the mirror, which complicates the structure, increases the occupied space, and increases the weight of the device. There are problems such as. Furthermore, even if the quick return mirror device disclosed in Patent Document 10 described above can suppress the bounce of the quick return mirror, the bounce of the sub mirror cannot be suppressed.

  The present invention has been made to solve the above-described problem, has a simple structure, can quickly suppress the residual vibration of the sub mirror supported by the main mirror (quick return mirror), and An object of the present invention is to provide a digital camera in which the mirror drive unit can be made compact.

  According to a first aspect of the present invention, there is provided a digital camera that enters the optical path of the imaging optical system, guides a part of the subject luminous flux from the imaging optical system to the viewfinder, and the optical path of the imaging optical system. And a main mirror portion including a quick return mirror that reciprocates between the second position where the subject light flux from the imaging optical system enters the photoelectric conversion element, and the main mirror portion is the second position. When returning from the first position to the first position, a stop position restricting means for restricting the stop position of the main mirror portion at the first position by colliding with at least a part of the main mirror portion in the vicinity of the first position. When the main mirror unit is stopped at the first position, a part of the subject light flux from the imaging optical system that passes through the main mirror unit is guided to the focus adjustment distance measuring element. It includes a sub-mirror unit having a chromatography, a support portion for supporting the sub-mirror section disposed on a portion of the substantially clause of vibration of the main mirror part caused by the collision.

  According to a second aspect of the present invention, in the digital camera according to the first aspect, the support portion is disposed at a position that does not overlap an antinode portion of vibration of the main mirror portion generated by the collision. Yes.

  A digital camera according to a third aspect of the present invention is the digital camera according to the first aspect, wherein the support portion is provided with a part constituting a rotation axis of the sub mirror portion.

  According to the present invention, it is possible to provide a digital camera that has a simple structure, can quickly suppress the residual vibration of the sub mirror supported by the main mirror, and can reduce the size of the mirror drive unit. it can.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view taken along the optical axis of a photographic lens showing a configuration of a main part of a single-lens reflex camera that is a digital camera according to an embodiment of the present invention. FIG. 2 is a perspective view of the mirror box portion of the single-lens reflex camera as viewed from the front side. FIG. 3 is a perspective view of the mirror unit of the single-lens reflex camera as seen from the front side, and shows a mirror entry position state. FIG. 4 is an enlarged schematic side view showing the vibration state at the entry position of the mirror frame and the sub mirror frame of the mirror unit.

  A single-lens reflex camera 1 according to this embodiment includes a camera body 2 and an interchangeable lens barrel 3 that can be attached to and detached from the camera body 2 as shown in FIG.

  The lens barrel 3 has a built-in photographing lens 3 a serving as an imaging optical system having a lens optical axis, and can be attached to the camera body 2 by a body mount 29.

  As shown in FIGS. 1 and 2, the camera body 2 includes a body mount 29 on the front surface as a component disposed inside the camera body 2 a, and incorporates the mirror unit 5 and the distance measuring sensor unit 6. The mirror box 4, the shutter unit 7 disposed in the rear part of the mirror box 4, the imaging unit 8, the finder unit 9 disposed in the upper part of the mirror box 4, and the camera control unit and each unit drive Part (not shown).

  The lens optical axis when the lens barrel 3 is attached to the camera body 2 is indicated by O in the figure. In the direction of the lens optical axis O, the subject side is the front side of the camera body 2 and the imaging side is the rear side. The left-right direction with respect to the lens optical axis O is defined as the x direction. In addition, the direction of the tangent of the rotational trajectory of the tip surface at the entry position P1 in a state where the mirror frame 15 (described later) holding the quick return mirror of the mirror unit 5 is in contact with the stopper 4a (described later) is defined as the y direction.

  A finder unit 9 built in the camera body 2 includes a focusing screen 11, a pentaprism 12, and an eyepiece lens 13 to constitute a finder optical system.

  The mirror unit 5 is disposed inside the mirror box 4, and includes a mirror frame 15 constituting a main mirror portion to which a quick return mirror 16 having a reflecting surface for reflecting a subject light beam is fixed to an upper surface portion, and a rear surface of the mirror frame 15. And a sub-mirror frame 17 that constitutes a sub-mirror unit that is rotatably supported by the unit and holds the sub-mirror 17a.

  The mirror frame 15 is urged in a state in which it can be rotated downward by a mirror urging spring 19 via a rotation shaft 18 along the x direction in the mirror box 4. When a mirror driving lever (not shown) is rotated in one direction by a mirror driving device (not shown), the mirror frame 15 is biased by a biasing spring (not shown) via a driven pin 15a. The mirror biasing spring 19 is rotationally driven upward (in the mirror up direction) against the biasing force of the mirror biasing spring 19 and comes into contact with the stopper 4b on the inner wall surface of the mirror box 4 and stops at a retracted position P2 (described later). At that time, the sub-mirror frame 17 disposed on the rear surface of the mirror frame 15 is also closed at the closed position Q2 (FIG. 4).

  On the other hand, when the mirror driving lever is driven to rotate in the reverse direction, the mirror driving lever is driven to rotate downward (in the mirror down direction) by the urging force of the mirror urging spring 19, and is provided on the inner wall surface 4f of the mirror box 4. It abuts against a stopper 4a which is a stop position restricting means and stops at an entry position P1 (described later). At that time, the sub-mirror frame 17 disposed on the back surface of the mirror frame 15 is also opened to the open position Q1 (FIG. 4) by the urging force of a toggle spring (not shown) in conjunction with the above-described rotation operation, and comes into contact with the stopper 4c.

  In a state where the mirror frame 15 is positioned at the entry position P1, which is the first position below, the quick return mirror 16 is positioned obliquely in the optical path of the subject light beam on the lens optical axis O (FIGS. 1 and 2). ). In this state, the subject luminous flux taken in via the photographing lens 3a is reflected by the quick return mirror 16 toward the upper finder unit 9, and finder observation is possible. Further, the sub-mirror frame 17 is in the open position Q1 (FIG. 4) obliquely placed on the optical axis O at the rear part of the mirror frame 15 as described above when the mirror frame 15 is at the entry position P1, Part of the subject luminous flux that has passed through a part of the return mirror 16 is reflected to the distance measuring sensor unit 6 side having the focus detection element, and the subject distance can be measured (ranging).

  In a state where the mirror frame 15 is positioned at the retracted position P2, which is the second position above, both the quick return mirror 16 and the sub mirror 17a held by the sub mirror frame 17 are retracted out of the optical path of the subject light beam. The subject luminous flux captured through 3a passes through the shutter unit 7 in the open state and forms an image on the photoelectric conversion surface of the image sensor that is the photoelectric conversion element of the image pickup unit 8. The imaging signal output from the imaging element is processed by the camera control unit, and a subject image signal is output.

  In the above-described mirror unit 5 in the present embodiment, a support structure in which the sub mirror 17 a held by the sub mirror frame 17 is not easily affected by the bounce of the mirror frame 15 is employed.

  Specifically, the mirror frame 15 bounces when it reaches the entry position P1 and contacts the stopper 4a, and at the same time, the mirror frame 15 itself exhibits a deformed state 15A due to natural vibration as shown in FIG. As shown in FIG. 4, the rotation shaft 21, which is a support portion that rotatably supports the sub-mirror frame 17 of the mirror frame 15, is positioned at a node position S 0 other than the above-described abdominal portion of the natural vibration of the mirror frame 15. Therefore, the amount of displacement of the rotation shaft 21 in the mirror frame rotation direction due to the natural vibration of the mirror frame 15 is small, the swing of the sub mirror frame 17 is suppressed, and the sub mirror 17a settles earlier. As a result, the distance measuring process by the reflected light of the subject light beam in the sub mirror 17a can be started promptly.

  FIG. 6 shows a vibration state when the rotation shaft 21A for rotatably supporting the sub mirror frame 17 is at a position S1 near the antinode other than the position of the natural vibration node of the mirror frame 15. In this case, a relatively long time is required until the rotating shaft 21A is displaced in the mirror frame rotating direction (in the direction of the arrow) and the sub mirror 17a is settled.

When the mirror unit 5 of the present embodiment is applied, as described above, the rotation shaft 21 for rotatably supporting the sub mirror frame 17 is arranged at the node position S0 in the natural vibration state of the mirror frame 15. Since the sub mirror 17a when the mirror frame 15 reaches the entry position P1 can be settled earlier, a quick focusing process can be performed without delaying the start of the distance measuring process. Further, it is not necessary to increase the number of components, and the mirror drive unit can be made compact. The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention at the implementation stage. It is possible to implement. Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements.

  The digital camera according to the present invention has a simple structure, can quickly suppress the residual vibration of the sub mirror supported by the main mirror (quick return mirror), and can reduce the size of the mirror drive unit. It can be used as a camera.

1 is a cross-sectional view taken along an optical axis of a photographic lens showing a configuration of a main part of a single-lens reflex camera that is a digital camera according to an embodiment of the present invention. It is the perspective view which looked at the mirror box part of the single-lens reflex camera of FIG. 1 from the front side. It is the perspective view which looked at the mirror unit of the single-lens reflex camera of FIG. 1 from the front side, Comprising: A mirror approach position state is shown. It is the typical side view which expanded and showed the vibration state in the approach position of the mirror frame of the mirror unit of FIG. 3, and a submirror frame. It is a schematic diagram which shows the structure of the principal part around the main mirror of the conventional single-lens reflex camera. FIG. 4 is a diagram showing a vibration state when a rotation shaft for rotatably supporting a sub mirror frame 17 is located at a position other than the position of a node in the natural vibration state of the mirror frame in a mirror unit of a normal single-lens reflex camera. is there.

Explanation of symbols

3a ... Photography lens (imaging optical system)
4a: Stopper (stop position regulating means)
8 ... Imaging unit (photoelectric conversion element)
15 ... Mirror frame (main mirror part)
16 ... Quick return mirror 17 ... Sub mirror frame (sub mirror part)
17a ... submirror 21 ... rotating shaft (supporting portion, submirror portion rotating shaft)
P1 ... entry position (first position)
P2 ... Retraction position (second position)
S0 ... (vibration node)

Claims (3)

A first position that enters the optical path of the imaging optical system, guides a part of the subject luminous flux from the imaging optical system to the viewfinder, and retreats from the optical path of the imaging optical system, and the subject luminous flux from the imaging optical system A main mirror portion including a quick return mirror that reciprocates between the second position to be incident on the photoelectric conversion element;
When the main mirror unit returns from the second position to the first position, it collides with at least a part of the main mirror unit in the vicinity of the first position, and the first position of the main mirror unit Stop position restricting means for restricting the stop position in
A sub-mirror comprising a sub-mirror that guides a part of a subject light beam from the imaging optical system that passes through the main mirror unit to the focus adjustment distance measuring element when the main mirror unit is stopped at the first position. And
A support part for supporting the sub-mirror part arranged at a portion of a vibration of the main mirror part caused by the collision;
A digital camera comprising:   The digital camera according to claim 1, wherein the support portion is disposed at a position that does not overlap an antinode portion of vibration of the main mirror portion generated by the collision.   The digital camera according to claim 1, wherein the support portion is provided with a part constituting a rotation shaft of the sub mirror portion.

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