JP2009258296A - Finder structure for single lens reflex camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a finder structure for a single lens reflex camera whose constitution itself is simple and which efficiently prevents dust from infiltrating from a mirror box side having a gap for adjustment. <P>SOLUTION: The finder structure for the single lens reflex camera includes: a pentagonal prism 22; a reflection mirror 6 reflecting light to the pentagonal prism 22; a screen 12; a screen holding frame 11 fit to the screen 12; a pentagonal prism supporting base 21 having a pentagonal prism supporting frame part; and the mirror box 5 supporting the reflection mirror 6, fit to the screen holding frame 11 while providing a gap S2 making the reflection mirror side communicate with the pentagonal prism side, and inserted while providing a gap S3 communicating with the gap from a surface of the screen 12 on the pentagonal prism 22 side in a direction crossing with the gap S2 between the screen holding frame 11 and the pentagonal prism supporting frame part. The gap S2 is larger in size than the gap S3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a finder structure to which a single-lens reflex camera is applied.

  Conventionally, an ordinary single-lens reflex camera (hereinafter, referred to as a single-lens reflex camera) includes a finder unit above a movable reflecting mirror for reflecting a photographing subject light beam, as is well known. FIG. 8 is an enlarged sectional view showing the arrangement of the main part of the finder unit of the conventional single-lens reflex camera.

  In the finder unit, during finder observation, the subject image formed on the focusing screen 103 is observed by the eyepiece lens 106 via the pentaprism 105 supported by the prism support base 104. The screen 103 is supported by the mirror box 101 via the screen support frame 102. However, it is necessary to finely adjust the mounting position in order to adjust the imaging position when the camera is assembled. Therefore, the screen support frame 102 is supported with an adjustment gap with respect to the mirror box 101.

  Further, in this conventional single-lens reflex camera, when the interchangeable lens is removed, dust enters from the body mount opening 108 a and adheres to the surfaces of the movable mirror 109 and the screen 103. The adhering dust is removed using a blower or the like.

  However, in the conventional single-lens reflex camera, when the surroundings of the movable mirror 109 and the screen 103 are cleaned using the blower or the like, dust is mixed with the air sent from the blower from the gap around the screen support frame 102. It enters inside and adheres to the back surface 103a (display plate 107, pentaprism 105 side) of the screen 103.

  Considering the dust entry path described above, as shown in FIG. 8, around the screen support frame 102, there are a front side gap S11 and a rear side gap S12 that lead from the inside of the mirror box 101 into the camera body. Clearances S13 and S14 communicating with the clearances S11 and S12 and leading to the back side of the screen 101 are provided. The gaps S13 and S14 are narrow gaps similar to the gaps S11 and S12. The air sent from the blower flows through the gaps S11 and S12 and simultaneously flows into the back surface 103a of the screen 103 through the gaps S13 and S14. . Therefore, there is a high possibility that dust mixed in the air sent from the blower flows into the back surface 103a of the screen 103 and adheres to the back surface 103a of the screen 103.

  FIG. 9 is a viewfinder observation image (magnified image) showing the state of dust adhering to the back surface 103a of the screen 103 after the periphery of the body mount opening 108a and the screen 103 is experimentally cleaned with a blower in the conventional single-lens reflex camera. This is an example. As shown in FIG. 9, a lot of dust G11 is attached around the photometric area Ar11 by the mark on the display plate 107 and the focus target Ar12. These adhering dust G11 cannot be eliminated unless the finder unit is removed, and increases with each cleaning.

  The present invention has been made to solve the above-described problems, and in the finder structure of a single-lens reflex camera, the configuration itself is simple, and dust entry from the mirror box side can be efficiently prevented. An object is to provide a finder structure.

  The finder structure of the single-lens reflex camera according to claim 1 of the present invention includes a pentaprism, a reflection mirror for reflecting a subject light beam to the pentaprism, a plate-like focusing screen, the focusing screen as the pentaprism and the A rectangular screen for holding the focusing screen having an opening for allowing observation image light to enter the focusing screen and a frame portion that fits around the focusing screen to be disposed between the reflecting mirror and the reflecting screen. A pentagonal prism support base having a holding frame and a pentaprism support frame part for supporting the pentaprism, and having an opening for allowing observation image light to enter the incident surface of the pentaprism at the center of the support frame part; The screen is rotatably supported by the reflection mirror. A first gap that communicates with the reflection mirror side and the pentaprism side on at least a part of a fitting surface between the inner periphery of the opening and the outer periphery of the screen holding frame; Further, at least a portion between the screen holding frame and the pentaprism support frame portion is provided with a second gap that communicates with the first gap from a surface of the screen on the pentaprism side. A mirror box inserted into the opening so that the pentaprism support frame portion covers the screen, and the first gap has a size larger than that of the second gap.

  The finder structure of the single-lens reflex camera according to claim 2 of the present invention is the finder structure of the single-lens reflex camera according to claim 1, wherein the finder structure for superimposing is provided between the screen and the incident surface of the pentaprism. A display board is arranged.

  The finder structure of the single-lens reflex camera according to claim 3 of the present invention is the finder structure of the single-lens reflex camera according to claim 1 or 2, in the first gap or a path following the first gap. Has an adhesive means for adsorbing dust on at least a part thereof.

  According to the present invention, it is possible to provide a finder structure of a single-lens reflex camera that has a simple configuration and can efficiently prevent dust from entering from the mirror box side.

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

  FIG. 1 is a perspective view of a single-lens reflex camera with a built-in finder structure according to an embodiment of the present invention with a part of an exterior cover removed. FIG. 2 is an exploded perspective view of the single-lens reflex camera. FIG. 3 is an exploded perspective view of the mirror box, screen unit, and finder unit of the single-lens reflex camera. FIG. 4 is a perspective view of the screen unit. FIG. 5 is an exploded perspective view showing the screen unit attached to the mirror box in the single-lens reflex camera. FIG. 6 is an enlarged cross-sectional view along the optical axis around the viewfinder structure portion mounted on the upper portion of the mirror box.

  In the single-lens reflex camera, the optical axis of the photographic lens to be mounted is indicated by O in the figure, the subject side along the photographic lens optical axis O of the camera is the front, and the imaging side (imaging side) is the rear. As a side, the following description will be given.

  As shown in FIG. 1, the single-lens reflex camera 1 of the present embodiment includes a front body 2 that also serves as an exterior body, a rear body (not shown), and a mirror box 5 incorporated in the camera body (not shown). Further, the electric control member such as the main control board 3 and the upper part of the mirror box 5 are mounted, and the screen unit 7 and the finder unit 8 (FIG. 3) constituting the finder structure part and the rear part of the mirror box 5 are assembled. A shutter unit 31 and an imaging unit 32 (FIG. 6) are provided.

  Note that an interchangeable lens barrel (not shown) having a photographic lens is attached to the single-lens reflex camera 1 in a detachable state on the body mount 33. A part of the subject light beam along the optical axis O from the photographing lens is reflected as a finder light beam (observation image light) on the finder unit 8 side by a movable mirror 6 described later at the optical path entrance position. The optical axis of is assumed to be Of.

  The mirror box 5 has an opening 5a for guiding the reflected light from the movable mirror 6 to the screen 12 and the incident surface side of the pentaprism 22, and a position below the opening 5a in the optical path of the subject luminous flux. A movable mirror 6 (FIG. 6) that can be rotated is disposed between an approach position that is located in an oblique position and a retracted position that is retracted upward from the optical path. Further, at least a part of the opening 5a on the upper side of the inner peripheral surface 5n is provided with a facing surface 5i that faces the outer peripheral surface of the screen unit 7 (FIGS. 5 and 6). The facing surface 5i is recessed from the inner peripheral surface 5n to the body mount portion side stepwise.

  Positioning pins 5c, 5d and position adjusting pins 5b, 5e, 5f serving as screen unit support portions are arranged on the left and right sides of the upper opening of the opening 5a of the mirror box 5.

  The finder unit 8 is fixed to the upper part of the opening 5 a of the mirror box 5, and is fixed to the upper part of the prism support 21 and a prism support 21 having an opening for allowing observation image light to enter the incident surface of the pentaprism 22. A prism prism 22, an eyepiece unit 23 fixed to the rear part of the prism support 21, a display plate 24 fixedly arranged on the incident surface side of the pentaprism 22 and having a photometric area indicator and a focus area indicator; It comprises a display board frame 25 and a superimpose display section as a photographing information display section (FIG. 3).

  The display plate 24 is fixedly supported on the prism support 21 while being separated from the incident surface of the pentaprism 22 by a predetermined distance. An imaging information display board (LCD) 26 and a prism 27 are arranged as a superimpose display section in the rear space between the pentaprism 22 and the display board 24 (FIG. 6).

  The screen unit 7 includes a rectangular screen support frame 11 having an opening, a focusing screen (hereinafter referred to as a screen) 12, and a screen pressing frame 13 (FIGS. 4 and 5).

  The screen support frame 11 is provided with positioning holes 11c, positioning elongated holes 11d, and position adjusting pin holes (reliefs) 11b, 11e, and 11f in four support portions protruding left and right (FIG. 5).

  The screen pressing frame 13 is a frame-like member made of a leaf spring having an opening for allowing observation image light to enter the screen 12. The screen pressing frame 13 presses the screen 12 inserted into the screen support frame 11 from the lower side, and the projections 13a, The screen 12 is held on the screen support frame 11 by engaging 13 b with the screen support frame 11.

  The screen unit 7 is pressed and fixed by the pressing plate springs 14 and 15 in a state where the screen unit 7 is positioned at the upper side of the opening 5 a of the mirror box 5.

  Specifically, the positioning hole 11c and the positioning elongated hole 11d of the screen support frame 11 are fitted into the positioning pins 5c and 5d of the mirror box 5, and the position adjusting pin is inserted into the position adjusting pin holes (relief) 11b, 11e and 11f. 5b, 5e, and 5f are inserted, and the screen unit 7 is placed on the upper surface of the opening of the mirror box 5. However, the adjustment washers 16, 17, and 18 are inserted into the position adjustment pins 5b, 5e, and 5f, and the screen support frame 11 is placed in an interposed state. At this time, the outer peripheral surface 11g below the screen support frame 11 is loosely fitted to the inner periphery of the opening 5a.

  Further, the three tip portions of the holding plate springs 14 and 15 are brought into contact with three points on the position adjusting pin holes 11b, 11e and 11f of the left and right support portions of the screen support frame 11, and are inserted into the screw insertion holes 14a and 15a. By screwing and fixing the inserted screws 19 and 20 into the screw holes 5g and 5h, the screen 12 of the screen unit 7 is fixed on the opening 5a of the mirror box 5 (FIG. 5).

  As for the position of the screen 12 described above, the position on the finder optical axis Of needs to be positioned at an accurate image formation position including the inclination, and the thicknesses of the adjustment washers 16, 17, 18 are selected at the time of assembly. The above position adjustment is performed by.

  As shown in FIG. 6, the finder unit 8 is positioned and fixed in the opening 5 a of the mirror box 5, and the display plate 24 is positioned with a gap with respect to the screen 12 of the screen unit 7. The front end and the rear end of the outer shape of the screen support frame 11 are supported with a gap with respect to the mirror box 5 and the prism support 21.

  More specifically, the front end of the screen support frame 11 is located in a state where there is a narrow gap S1 sandwiched between the opening inner peripheral surface 5n and the screen support frame outer peripheral surface 11g in the opening 5a. The upper part following the part S1 is a larger first flow path sandwiched between the opposing surface 5i and the outer peripheral surface 11g, and the gap part S2, which is the first gap, goes straight (a direction substantially parallel to the viewfinder optical axis Of). Is formed. The gap S2 communicates with the inside of the camera through the outer periphery of the pentaprism 22. A second flow path is provided between the screen support frame 11 and the prism support base 21 so as to intersect with the gap S2 in a direction substantially perpendicular to the gap S2, and a gap S3 that is the second gap is provided in communication. It has been. The gap S3 is a gap necessary for adjusting the position of the screen 12 in the optical axis Of direction, and communicates with the back surface 12a (the pentaprism 22 side) of the screen 12. The gap portion S3 is narrower (smaller) than the gap portion S2.

  An adhesive tape 28, which is an adhesive means for adhering dust, is affixed to the path 5k above the gap S2 (FIG. 6).

  On the other hand, at the rear side end portion of the screen support frame 11, it is behind the lower surface of the rear end portion of the prism support base 21 and the opening 5 a of the mirror box 5, and the surface of the opening end of the screen support frame 11 on the movable mirror 6 side. Is a relatively wide first flow path with a gap portion S2, and a gap portion S4 which is a first gap is provided between the substantially opposed surface 5j. This gap S4 passes through the back of the finder unit 8 and communicates with the inside of the camera. A narrower second flow path which is provided so as to intersect the gap S4 in a substantially orthogonal direction and communicates with the back surface 12a of the screen 12, and the gap S5 which is the second gap is the rear end of the screen support frame 11. And the prism support 21. Above the gap portion S5, a gap necessary for adjusting the position of the screen 12 in the optical axis Of direction is provided.

  An adhesive tape 29, which is an adhesive means for adhering dust, is attached to the path 5m on the rear side of the gap S4 (FIG. 6).

  In the finder structure having the above-described configuration, when the opening 33a of the body mount 33 is in an open state, dust enters from the opening 33a and adheres around the movable mirror 6 and the screen 12. The dust is usually removed using air blown from the blower. The flow of air containing dust at that time will be described. At the front side end of the screen support frame 11, the air containing dust passes through the gap S1 and passes through the gap S2 to the inside of the camera. Although it flows, the gap portion S2 flows at a certain flow velocity, so that the pressure of the gap portion S3 on the side is lowered, and air is sucked from the gap portion S3. Therefore, the dust mixed in the air hardly reaches the back surface 12a of the screen 12.

  On the other hand, the dust-containing air also flows toward the inside of the camera through the gap S4 at the rear side end of the screen support frame 11. In the gap portion S4, the air flows at a certain flow velocity, so that the pressure in the gap portion S5 on the side thereof is lowered, and rather, the air is sucked from the gap portion S5. Therefore, the dust mixed in the air similarly reaches the back surface 12a of the screen 12 very little.

  The dust-containing air passes through the gap S2 or the gap S4 and then passes over the path 5i or 5k, and the dust mixed with the air is attached to the adhesive tape. It adheres to 28 or 29. Therefore, the rate at which the dust reaches the inside of the camera is reduced.

  FIG. 7 is a viewfinder observation showing the state of dust adhering to the back surface 12a of the screen 12 after the dust around the screen 12 is experimentally cleaned by a blower in the finder structure portion of the single-lens reflex camera 1 of the present embodiment described above. It is an image (enlarged view). As shown in FIG. 7, the photometric area Ar1 by the sign on the display plate 24 and the dust G1 adhering to the periphery of the focus target Ar2 are extremely different from the case of FIG. 9 by the test using the conventional single-lens reflex camera described above. It is running low. In the case of FIGS. 7 and 9, in the state before both tests are performed, there is no dust on the back surface of the screen.

  As described above, according to the finder structure portion of the single-lens reflex camera 1 of the present embodiment, the clearances S1, S2,. By adopting the shapes of S3 and S4, dust entering the back side of the screen 12 can be reduced. Furthermore, the dust sent into the camera can be reduced by sticking the adhesive tape to the rear path following the gaps S2 and S4.

  In the description of the present embodiment, the pentaprism 22 is used for the finder structure, but a hollow pentaprism-shaped reflecting member composed of three reflecting mirrors including a known roof mirror is used instead of the pentaprism. The finder reflection means used may be applied.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention at the stage of implementation. 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 finder structure of the single-lens reflex camera of the present invention has a simple configuration and can be used as a finder structure of a single-lens reflex camera that can efficiently prevent dust from entering from the mirror box side.

It is a perspective view in the state where a part of the exterior cover of the single-lens reflex camera which incorporates the finder structure part of one embodiment of the present invention was removed. It is a disassembled perspective view of the single-lens reflex camera of FIG. FIG. 2 is an exploded perspective view of a mirror box, a screen unit, and a finder unit of the single-lens reflex camera of FIG. 1. FIG. 4 is a perspective view of the screen unit of FIG. 3. It is a disassembled perspective view which shows the attachment state of the screen unit to the mirror box in the single-lens reflex camera of FIG. It is an expanded sectional view along the optical axis which shows arrangement | positioning of the finder structure part with which the upper part of the mirror box of FIG. 5 is mounted | worn. FIG. 2 is a viewfinder observation image (enlarged view) showing a state of dust adhering to the back surface of the screen after the dust around the screen is experimentally cleaned by a blower in the viewfinder structure portion of the single-lens reflex camera of FIG. 1. It is an expanded sectional view along the optical axis which shows arrangement | positioning of the finder unit in the conventional single-lens reflex camera. FIG. 9 is a viewfinder observation image (enlarged view) showing a state of dust adhering to the back surface of the screen after the dust around the screen is experimentally cleaned by a blower in the viewfinder unit in the single-lens reflex camera of FIG. 8.

Explanation of symbols

5 ... Mirror box 6 ... Reflecting mirror 11 ... Screen holding frame 12 ... Screen (focusing screen)
21 ... Prism support base (Pental prism support base)
22… Pental prism 26… Superimpose LCD
(Superimposed display board)
28, 29 ... Adhesive tape (adhesive means)
S2, S4 ... Gap (first gap)
S3, S5 ... Gap (second gap)

Claims (3)

Penta prism,
A reflection mirror that reflects the subject luminous flux to the pentaprism;
A plate-like focusing screen;
In order to dispose the focusing screen between the pentaprism and the reflection mirror, the focusing screen has an opening for allowing observation image light to enter the focusing screen and a frame portion that fits around the focusing screen. A rectangular screen holding frame for holding the focusing screen;
A pentaprism support frame portion that supports the pentaprism, and a pentaprism support base having an opening for allowing observation image light to enter the incident surface of the pentaprism at the center of the support frame portion;
The reflection mirror is rotatably supported and has an opening for supporting the screen holding frame, and the reflection mirror side and the above are provided on at least a part of a fitting surface between the inner periphery of the opening and the outer periphery of the screen holding frame. A first gap communicating with the pentaprism side is provided, and the first gap from the surface of the screen to the pentaprism side is at least partially between the screen holding frame and the pentaprism support frame portion. A mirror box inserted into the opening so that the pentaprism support frame portion covers the screen so as to provide a second gap communicating with
A viewfinder structure for a single-lens reflex camera, wherein the first gap has a size larger than that of the second gap.   2. A finder structure for a single-lens reflex camera according to claim 1, wherein a display panel for superimposing is disposed between the screen and the incident surface of the pentaprism.   3. A finder for a single-lens reflex camera according to claim 1, wherein adhesive means for adsorbing dust is disposed at least in part in the first gap or a path following the first gap. Construction.

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