JP4926880B2 - Camera focusing screen holding mechanism - Google Patents

Description

  The present invention relates to a focusing screen holding mechanism such as a single-lens reflex camera or a still video camera, and more particularly to a focusing screen holding mechanism of a camera having a removable focusing screen.

  As a conventional focusing screen holding mechanism of a camera, for example, a holding frame that holds the focusing screen, hinge means that supports the holding frame so that it can be opened and closed, and a holding member that locks and holds the holding frame in a closed state. There is what is provided (Patent Document 1).

  FIG. 9 shows a specific example of a conventional focusing screen holding mechanism of a camera.

  The focusing screen holding mechanism includes a prism holder 100 that holds a condenser lens (not shown) and a pentaprism (not shown). The prism holder 100 is a box-shaped support, and holds a reflecting plate 102 and a focusing screen 101 on the lower side of the prism holder 100 for lighting an index indicating a focus detection area at the time of focus detection.

  The rear end of the prism holder 100 is provided with a bearing (hinge means) 106 that serves as the center of rotation of the holding frame 103 that houses the focusing screen 101 and a holding surface of the reflecting plate 102. A mounting surface for the member 104 is provided.

  The holding member 104 is a thin plate member fixed to the front end of the prism holder 100. The holding member 104 is provided with two holes 104a and 104b and one spring part 10f at the center, and two arm parts 104c and 104d on both sides. It is done.

  Then, after inserting the pin 105 into the two holes 104a and 104b of the holding member 104 and the corresponding hole (not shown) of the prism holder 100, the pin 105 is caulked, so that the holding member 104 becomes the prism holder. It is fixed to the front end of 100.

  The reflection plate 102 is provided with two protrusions 102h and 102i at the front end, and the two protrusions 102h and 102i are supported from below by the arm portions 104c and 104d of the holding member.

  Further, a projection 103a is provided at the front end portion of the holding frame 103, and the projection 103a is elastically locked to a hole 104e provided in the spring portion 104f of the holding member 104, whereby a focusing screen is obtained. 101 is held in the holding frame 103.

When the focusing screen 101 is replaced, the locked state between the hole 104e and the protrusion 103a of the holding frame 103 is released using the elasticity of the spring 104e of the holding member 104. As a result, the holding frame 103 is rotated in a direction to open the bearing 106 as a fulcrum, and the focusing screen 101 can be easily replaced.
JP-A-8-54666

  By the way, in the above-mentioned Patent Document 1, the spring portion 104f is provided with the spring portion 104f so that the protrusion 103a of the holding frame 103 locked to the hole portion 104e provided in the spring portion 104f of the holding member 104 is not inadvertently removed due to an impact or the like. Must have sufficient elastic force.

  However, since the holding member 104 must be arranged in a narrow space due to the layout in the camera, it is difficult to obtain a sufficient elastic force by increasing the length of the spring portion 104f. Therefore, there is a possibility that the protrusion 103a of the holding frame 103 may be inadvertently detached from the hole 104e of the holding member 104 due to an impact such as a drop due to individual variation or aging of the holding member 104.

  Therefore, the present invention has an object to provide a focusing screen holding mechanism for a camera that can prevent the holding frame from being inadvertently detached from the holding member due to an impact such as a drop due to individual variation or aging of the holding member. And

In order to achieve the above object, the present invention includes a focusing screen disposed in a finder optical path, a holding frame that holds the focusing screen, and a holding member that holds and holds the holding frame. In the focusing screen holding mechanism in which the focusing screen can be replaced by releasing the locking of the member and moving the holding frame, the holding member is a first member for releasing the locking with the holding frame. A first spring portion that is elastically deformed in the deformation direction , and one end portion in a second deformation direction different from the first deformation direction is movable in the second deformation direction through an elongated hole portion. and supported by, said first elastically deformed at the same time to said second deformation direction and the elastic deformation of the spring portion, the second spring portion to which the first spring portion is disperse stress generated when the elastic deformation It is having, characterized in that.

  According to the present invention, internal stress generated by deformation of the holding member can be dispersed, and sufficient elastic force can be stably generated in the holding member without plastic deformation. Accordingly, it is possible to prevent the holding frame from being inadvertently detached from the holding member due to an impact such as a drop due to individual variation or aging of the holding member.

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

  FIG. 1 is a schematic cross-sectional view of a single-lens reflex camera as an example of a camera provided with a focusing screen holding mechanism as an example of an embodiment of the present invention.

  As shown in FIG. 1, in this single-lens reflex camera, a photographic lens 1 including a photographic optical system 2 is detachably attached to a camera body 3. The camera body 3 includes a mirror 4 that reflects at least a part of the light transmitted through the photographing optical system 2. At the time of non-photographing, the light beam transmitted through the photographing optical system 2 is guided to the finder optical system by the mirror 4. At the time of shooting, the mirror 4 is retracted, and the light beam transmitted through the shooting optical system 2 reaches the image sensor 5.

  The finder optical system includes a focusing screen 7 (shaded hatched portion in FIG. 1), a reflecting plate 8 (lattice hatched portion in FIG. 1), and a washer member 9 held by the mirror box 6.

  The focusing screen 7 has a mat surface 7b for forming an optical image from the light beam guided by the mirror 4, and a Fresnel surface 7c for guiding more light to the downstream finder optical system.

  The reflecting plate 8 has a reflecting surface that forms an index indicating the focus detection area, reflects the light projected from the focus detection area lighting optical system 13, and lights the index indicating the focus detection area during focus detection. Make it possible.

  The washer member 9 is disposed between the focusing screen 7 and the reflecting plate 8 so that the mat surface 7b of the focusing screen 7 can be disposed at a position symmetrical to the imaging surface of the image sensor 5 and the mirror 7. Adjustment parts to be. By arranging in this way, it is possible to align the focus of the actually captured image and the observed finder image.

  FIG. 2 is a perspective view of the focusing screen 7, the reflecting plate 8, and the washer member 9.

  In FIG. 2, the protrusion 8a of the reflecting plate 8, the protrusions 9a and 9d of the washer member 9, and the protrusion 7a of the focusing screen 7 are arranged on the image sensor 5 side (right side in FIG. 1) in the camera. The focusing screen 7, the reflector 8, and the washer member 9 are fitted in holes (not shown) provided in the mirror box 6 in the respective protrusions 7 a, 8 a, 9 a, and the left and right direction of the camera (FIG. 1). Positioning in the depth direction of the paper surface).

  Returning to FIG. 1, the finder optical system further includes a field mask 10, a pentaprism 11, an eyepiece optical system 12, a focus detection region lighting optical system 13, and an LED substrate 14.

  The field mask 10 determines the field of view of the finder optical system, and is positioned and fixed with respect to the mirror box 6. The pentaprism 11 reflects the light transmitted through the focusing screen 7 and guides the light to the eyepiece optical system 12.

  In the present embodiment, the eyepiece optical system 12 includes three lenses 12a, 12b, and 12c, and the diopter can be adjusted by moving the lens 12b in the optical axis direction. The focus detection area lighting optical system 13 guides the light emitted from the LED mounted on the LED substrate 14 to an index 8b (see FIG. 2) indicating the focus detection area formed on the reflection surface of the reflection plate 8. The light reflected from the reflecting plate 8 passes through the pentaprism 11 and the eyepiece optical system 12 again, and the fan observer can observe the index 8b in a state where it overlaps the viewfinder optical image.

  The index 8b indicates three focus detection areas, and can be lit independently by the focus detection area lighting optical system 13 and the LEDs mounted on the LED substrate 14.

  If the field mask 10 is disposed in the vicinity of the mat surface 7b of the focusing screen 7, the diopter between the end surface of the field mask 10 and the optical image projected on the mat surface 7b can be matched. In the present embodiment, priority is given to the workability of exchanging the washer member 9 and the diopter shift between the index surface 8b indicating the focus detection area of the reflecting plate 8 and the mat surface 7b of the focusing screen 7 as described above.

  In the present embodiment, in order to prevent stray light from entering the finder system, the focusing screen 7, the reflecting plate 8, the washer member 9, and the incident surface of the pentaprism 11 are inclined with respect to the optical axis of the photographing lens. However, this is not always necessary, and the incident surface may be arranged parallel to the optical axis of the photographing lens.

  Next, a focusing screen holding mechanism as an example of an embodiment of the present invention will be described with reference to FIGS.

  3A and 3B are perspective views for explaining a focusing screen holding mechanism as an example of the embodiment of the present invention. FIG. 3A is a storage state of the focusing screen, and FIG. 3B is a replaceable focusing screen. State.

  As shown in FIG. 3, the focusing screen holding mechanism of the present embodiment locks the holding frame 15 that holds the focusing screen 7 and the holding frame 15 when the focusing screen 7 is stored (FIG. 3A). And a holding member 19 for holding.

  The holding frame 15 is integrally assembled with a push-up spring 16 that pushes up the focusing screen 7.

  4A and 4B are perspective views for explaining a method of assembling the push-up spring 16 to the holding frame 15, wherein FIG. 4A shows a state before assembly, and FIG. 4B shows a state after assembly.

  In order to assemble the push-up spring 16 to the holding frame 15, first, as shown in FIG. 4A, the hooking portion 16a of the push-up spring 16 is deformed in the direction of the arrow A while the angle to the long hole portion 15a of the holding frame 15 is changed. Insert in phase. Next, the push-up spring 16 is deformed in the direction of arrow B (from top to bottom in FIG. 1) and hooked on a side hook portion 15 c provided on the side surface of the holding frame 15.

  As a result, the push-up spring 16 is fixed at a total of five locations including the long hole portions 15a (two locations), the side hook portions 15c (two locations), and the front end hook portion 15d of the holding frame 15. Accordingly, the push-up spring 16 can be disposed at a position where the finder light flux is not blocked without the push-up spring 16 being carelessly removed.

  As shown in FIG. 4 (b), the push-up portion 16 b of the push-up spring 16 pushes the focusing screen 7 upward when the focusing screen 7 is stored, and the mirror box 6 abuts together with the reflector 8 and the washer member 9. Press against the surface (not shown). Thereby, even if the replacement operation of the focusing screen 7 is repeatedly performed, the focusing screen 7 can be accommodated in the camera at the same height, that is, at the same optical position as the imaging surface of the imaging device 5.

  As shown in FIG. 4B, a cushioning material 17 is provided on the bottom of the front end side of the holding frame 16, and the cushioning material 17 serves as a stopper when the mirror 4 is retracted during photographing. The buffer material 17 is held by a buffer material holding member 18 fixed to the holding frame 15.

  As shown in FIG. 3A, the holding member 19 has an arm at one end portion (left end portion in FIG. 3) in the longitudinal direction of a spring portion (second spring portion) 19j that is long in the left-right direction (left-right direction of the camera). The portions 19a and 19b are provided, and the arm portions 19c and 19d are provided at the other end (the right end in FIG. 3).

  In the exchangeable state of the focusing screen 7 (FIG. 3B), the projections 9b and 9c (FIG. 2) of the washer member 9 are held by the tips of the arm portions 19a and 19d, respectively, and the projection of the washer member 9 9a and 9d (FIG. 2) are held by holes (not shown) of the mirror box 6. Thereby, it is possible to prevent the washer member 9 from dropping when the focusing screen 7 is replaced.

  Similarly, the projections 8c and 8d (FIG. 2) of the reflector 8 are held by the arms 19b and 19c, respectively, and the projection 8a of the reflector 8 is held by the hole (not shown) of the mirror box 6. When the focusing screen 7 is replaced, the reflecting plate 8 can be prevented from dropping.

  The arm portions 19b and 19c generate a biasing force in the optical axis direction of the photographing lens (right direction in FIG. 1) and in the normal direction of the reflection plate 8 (upward direction in FIG. 1). Hit 6 The reflector 8 is abutted against the mirror box 6 in the right direction in FIG. 1 to enable high-precision positioning in the optical axis direction of the photographic lens, and the reflector 8 is abutted against the mirror box 6 in the upward direction of FIG. By hitting, dust and the like can be prevented from entering the finder optical system.

  As shown in FIG. 3A, a hinge shaft 21 is provided at the rear end of the holding frame 15 so as to rotatably support the holding frame 15 when the focusing screen 7 is replaced. The hinge shaft 21 is supported by fitting in a hole (not shown) provided in the mirror box 6.

  Next, a locking mechanism between the holding frame 15 and the holding member 19 will be described with reference to FIGS. 5 and 6.

  5A shows a state where the holding frame 15 and the holding member 19 are locked, and FIG. 5B shows a state where the locking between the holding frame 15 and the holding member 19 is released. It is. 6A is a cross-sectional view as viewed from the right side of FIG. 5A, and FIG. 6B is a cross-sectional view as viewed from the right side of FIG. 5B.

  The state in which the holding frame 15 and the holding member 19 are locked corresponds to the storage state of the focusing screen 7, and the state in which the holding frame 15 and the holding member 19 are unlocked is in the focusing screen 7. Corresponds to the exchangeable state.

  As shown in FIG. 5A, when the focusing screen 7 is stored, the protrusion 15b provided at the center of the holding frame 15 in the left-right direction is the center of the spring 19j of the holding member 19 in the left-right direction. It is elastically locked to a locking part 19i provided on the.

  In order to change the focusing screen 7 to a replaceable state from this state, the knob portion (first spring portion) 19h provided on the lower side of the locking portion 19i of the holding member 19 is moved to the arrow in FIG. Elastically deform in the direction.

  As a result, the locking portion 19i of the holding member 19 and the protrusion 15b of the holding frame 15 are unlocked, and the holding frame 15 rotates about the hinge shaft 21 by the urging force of the push-up spring 16, and the mirror box It moves to the position of a stopper part (not shown) provided in 6. As a result, the focusing screen 7 loses position restrictions other than the left-right direction of the camera (left-right direction in FIG. 5A), and moves to the position of the rotated holding frame 15 depending on the posture of the camera. Become.

  As described above, since the position of the focusing screen 7 in the left-right direction of the camera is regulated by the protrusion 7a fitted in the hole (not shown) of the mirror box 6, the focusing is performed in a state where the position is restricted only in the left-right direction of the camera. The screen 7 moves together with the holding frame 15.

  In order to change the focusing screen 7 from the replaceable state to the retracted state, the holding frame 15 is lifted toward the holding member 19 so that the protrusion 15b of the holding frame 15 causes the knob portion 19h of the holding member 19 to move to the position shown in FIG. It is pushed up in the direction of the arrow and is locked to the locking portion 19 i of the holding member 19.

  When the focusing screen 7 is stored, the holding frame 15 has a gap 50 between the hinge shaft 21 and the gap 50 that can slightly move in the camera front-rear direction (left-right direction in FIG. 6). Then, the knob portion 19 h of the holding member 19 urges both the holding frame 15 and the focusing screen 7 to the rear of the camera (rightward in FIG. 6A) by the elastic force and abuts against the mirror box 6. With this urging force, the focusing screen 7 can be stored in the holding frame 15 with high accuracy with respect to the position in the front-rear direction of the camera even when the replacement operation of the focusing screen 7 is repeated.

  As described above, the focusing screen 7 is urged rearward of the camera (rightward in FIG. 6A) by the knob portion 19h of the holding member 19 during storage, and is moved upward by the push-up spring 16 (in FIG. 6A). It is energized upward. In this case, by setting the frictional force of the focusing screen 7 by the respective urging forces to be sufficiently smaller than the respective urging forces, the position when the focusing screen 7 is stored can be accurately guaranteed.

  For example, as shown in FIG. 7, the biasing force 51 by the holding member 19 generates a frictional force 52 against the biasing force 53 of the focusing screen push-up spring 16. The focusing screen 7 can be reliably pushed up by setting the biasing force 53 of the push-up spring 16 sufficiently large with respect to the frictional force 52.

  As shown in FIG. 8, the focusing screen holding mechanism configured as described above has a front surface covered with a cover member 20.

  With reference to FIG. 8, the fixing method of the cover member 20 and the holding member 19 is demonstrated.

  The cover member 20 is a plate-like member that is long in the left-right direction of the camera. Holes 20b and 20d are formed at one end in the longitudinal direction (left end in FIG. 8), and the other end (right end in FIG. 8). ) Are formed with holes 20a and 20c. Further, a long hole portion 19f is formed at one end portion (left end portion in FIG. 8) of the spring portion 19j of the holding member 19, and a hole portion 19e, at the other end portion (right end portion in FIG. 8). 19g is formed. These holes 19e, 19g, 20b, 20d, 20a, 20c and the long hole 19f are arranged outside the width of the focusing screen 7 accommodated in the holding frame 15.

  The holes 20a and 20b of the cover member 20 are fitted into the bosses 6a and 6b of the mirror box 6 together with the holes 19e and 19f of the holding member 19 and positioned and fixed to the mirror box 6. The cover member 20 is fixed to the mirror box 6 with screws through the holes 20c and 20d.

  The hole 19g of the holding member 19 is fixed simultaneously with the screw fixing of the hole 20c of the cover member 20. When the screw of the hole 20d of the cover member 20 is fixed, the holding member 19 is disposed between the cover member 20 and the mirror box 6, and has a slight gap in the direction of the photographic lens optical axis.

  By fixing the holding member 19 in this manner, even when the knob portion 19h of the holding member 19 is elastically deformed when the focusing screen 7 is exchanged, the hole portion 19e and the hole portion 19g of the holding member 19 remain in the mirror box 6. No displacement is generated because it is positioned and fixed to.

  On the other hand, the long hole portion 19f of the holding member 19 is not screw-fixed and has a gap in the direction of the photographic lens optical axis. Therefore, when the long hole portion 19f moves in the left-right direction of the camera, the spring portion 19j of the holding member 19 can be elastically deformed in the left-right direction of the camera.

That is, in the focusing screen holding mechanism of the present embodiment, the knob portion 19h of the holding member 19 is elastically deformed in the camera front-rear direction (first deformation direction), and the spring portion 19j of the holding member 19 is in the camera left-right direction (second direction). Elastic deformation in the deformation direction). In this case, since the displacement of the holding member 19 is regulated further outside the width of the focusing screen 7, the length L of the spring portion 19j of the holding member 19 can be made sufficiently long.

  Therefore, in the focusing screen holding mechanism of this embodiment, internal stress generated by the deformation of the holding member 19 can be dispersed, and sufficient elastic force can be stably generated without plastic deformation. Thereby, it is possible to prevent the protrusion 15b of the holding frame 15 from being inadvertently detached from the engaging portion 19i of the holding member 19 due to an impact such as a drop due to individual variation or aging of the holding member 19.

  Further, since the deformation direction of the spring portion 19j of the holding member 19 is substantially perpendicular to the deformation direction of the knob portion 19h and the optical axis direction of the finder optical path, the design and layout have a relatively high degree of freedom within the camera. It can be performed.

  Furthermore, since the deformation restricting positions 19e and 19f of the holding member 19 are further outside the width of the focusing screen 7, it is possible to prevent the screw internal thread portion and the finder effective light beam from interfering with each other. As a result, it is possible to use a screw fixing method that is cheaper and has better disassembly workability than caulking, etc., and as a result, it is possible to replace a single part at the time of part replacement, thereby reducing the replacement cost. .

  Furthermore, since the deformation restricting positions 19e and 19f of the holding member 19 are disposed between the spring portion 19j of the holding member 19 and the arm portions 19a to 19d, the arm portions 19a to 19d are affected by the deformation of the spring portion 19j. The reflector 8 and the washer member 9 can be held without receiving.

  In addition, this invention is not limited to what was illustrated to the said embodiment, In the range which does not deviate from the summary of this invention, it can change suitably.

It is a schematic sectional drawing of the single-lens reflex camera provided with the focusing screen holding | maintenance mechanism which is an example of embodiment of this invention. It is a perspective view of a focusing screen, a reflecting plate, and a washer member. It is a perspective view for demonstrating the focusing screen holding | maintenance mechanism which is an example of embodiment of this invention, (a) is the accommodation state of a focusing screen, (b) is the exchangeable state of a focusing screen. It is a perspective view for demonstrating the method of assembling a raising spring to a holding frame, (a) is the state before an assembly | attachment, (b) is the state after an assembly | attachment. It is a figure for demonstrating the latching mechanism of a holding frame and a holding member, (a) is a latching state, (b) is a latch release state. It is sectional drawing seen from the right side of FIG. 5, (a) is a latching state, (b) is a latching release state. It is explanatory drawing for demonstrating the relationship between the urging | biasing force by a holding member, the urging | biasing force of a raising spring, and a frictional force. It is a disassembled perspective view for demonstrating the fixing method of a cover member and a holding member. It is a disassembled perspective view for demonstrating the conventional focusing screen holding mechanism.

Explanation of symbols

7 Focusing screen 8 Reflecting plate 9 Washer member 15 Holding frame 15b Protruding portion 19 Holding member 19h Knob portion 19i Locking portion 19j Spring portion 20 Cover member

Claims (4)

A focusing screen disposed in the finder optical path, a holding frame that holds the focusing screen, and a holding member that holds and holds the holding frame,
In the focusing screen holding mechanism capable of exchanging the focusing screen by releasing the locking of the holding member and moving the holding frame,
The holding member includes a first spring portion that is elastically deformed in a first deformation direction in order to release the engagement with the holding frame, and one of the second deformation directions different from the first deformation direction . An end portion is supported through the elongated hole portion so as to be movable in the second deformation direction, and is elastically deformed in the second deformation direction simultaneously with the elastic deformation of the first spring portion , whereby the first spring A focusing screen holding mechanism for a camera, comprising: a second spring portion for dispersing stress generated when the portion is elastically deformed .   2. The camera focusing according to claim 1, wherein the second deformation direction is substantially orthogonal to the first deformation direction and substantially orthogonal to an optical axis direction of the finder optical path. Screen holding mechanism. The holding member has at least two deformation restriction positions, and an arm portion that holds a member different from the focusing screen,
The focusing screen holding mechanism for a camera according to claim 1, wherein the deformation restricting position is disposed between the second spring portion and the arm portion.   4. The focusing screen holding mechanism for a camera according to claim 3, wherein the deformation restricting position is disposed outside a width of the focusing screen.

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