JP2009037140A - Finder device and camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently remove dust from a space between two optical members. <P>SOLUTION: A space SP between a condenser lens 14 and a pentagonal prism 17 is a space surrounded by the wall part of a prism box 8 in all directions. By providing an air hole 8a at as a high position as the space SP on the wall part of the prism box 8, air is made to blow straight to the space SP from the outside, so that the dust in the space SP is effectively removed without weakening the power of the air. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a finder device and a camera that take measures against dust.

  If dust adheres to the optical components constituting the camera finder device, the dust may be overlapped with the viewfinder image. In particular, dust attached to optical components close to the focal plane is conspicuous, giving the photographer an unpleasant feeling. Part of the finder component that can be replaced by the user or dust attached to the part facing the mirror box can be removed using a blower, etc., but the part facing the closed space in the finder unit The dust adhering to the surface could not be removed without disassembling the finder device.

  In order to solve this problem, there is a finder device that can introduce high-pressure air into the closed space so as to eliminate dust (for example, see Patent Document 1). In this finder apparatus, a space between two optical members (condenser lens and pentaprism) is a closed space surrounded by a finder holding member, and an air hole for sending air into the closed space is a holding member. Is provided. High-pressure air is sent into the closed space through the air holes, and the air in the other air holes is discharged to remove dust in the closed space. Thereafter, all the air holes are closed to prevent new dust from entering the enclosed space.

JP-A-11-109443 (FIG. 7)

  However, in the configuration of Patent Document 1, since the air hole of the finder holding member is provided on the side of the pentaprism, compressed air cannot be directly fed into the space between the condenser lens and the pentaprism. That is, there is a bent air passage from the air hole to the space, and the high-pressure air sent from the air hole flows into the space after hitting the wall of the air passage. For this reason, the momentum of the air flowing into the space declines, and the waste cannot be discharged efficiently.

In the finder device according to the present invention, a plurality of optical members are stacked and held on a holding member, and a space surrounded by a wall portion of the holding member is formed between two optical members facing each other. The wall portion of the holding member is provided with a plurality of air holes communicating with the closed space and the outside, and at least one air hole is located between the two optical members in the stacking direction of the plurality of optical members. It is provided at the same position as the space.
In another finder apparatus of the present invention, the at least one air hole is provided at a position where air from the outside can flow into the space between the two optical members in a substantially straight line.
The camera according to the present invention includes the above-described finder device.

  According to the present invention, dust can be efficiently removed from the space between the two optical members.

An embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is an overall configuration diagram of a digital single-lens reflex camera according to the present embodiment. Reference numeral 1 denotes a camera body, 2 denotes a front body attached to the camera body 1, and 3 denotes a lens mount to which an interchangeable lens (not shown) is attached. The front body 2 forms a mirror box MB in the camera body 1 and holds a penta unit PU as shown in FIG. The mirror unit MU arranged in the mirror box MB is composed of the main mirror 4 and the sub mirror 5, and is rotatable between a standby position inserted into the photographing optical path and a photographing position retracted from the photographing optical path.

  When the mirror unit MU is at the standby position, a part of the transmitted light beam of the photographing lens is reflected by the main mirror 4 and guided to the penta unit PU, and the light emitted from the penta prism 17 passes through the eyepieces 18 to 20. Observed. A finder device is constituted by the penta unit PU and the eyepieces 18 to 20. On the other hand, a part of the light beam transmitted through the main mirror 4 is reflected by the sub-mirror 5 and guided to the focus detection module AFM to contribute to focus detection. When shooting is instructed, the mirror unit MU is flipped up to the shooting position, and the transmitted light flux of the shooting lens is guided to the image sensor 7 via the shutter 6.

3 is an exploded perspective view of the penta unit PU, and FIG. 4 is a cross-sectional view after assembly.
The penta unit PU is formed by holding a plurality of components 9 to 17 (detailed below) stacked in the direction of the reflection optical axis of the main mirror 4 in a prism box 8 as a holding member. By attaching the prism box 8 to the upper part of the front body 2, the penta unit PU is integrated with the front body 2.

  The focusing screen 10 is fixed to the prism box 8 via the screen pressing frame 9. In a camera in which the focusing screen 10 can be replaced by a user, dust can be easily removed by removing the focusing screen 10. On the focusing screen 10, a field mask 11 for limiting the finder field range is disposed, and further, a diffusion type liquid crystal 12 is disposed thereon. The diffusive liquid crystal 12 is for changing the observation range of the finder image in accordance with the change of the recording range of the image sensor 7. A condenser lens 14 is disposed above the diffusing liquid crystal 12 via a spacer 13. The condenser lens 14 corrects distortion and plays a role of condensing the diffused light from the focus surface at the eye point.

  A field mask 16 and a pentaprism 17 are arranged above the condenser lens 14 with a spacer 15 in between. The spacer 15 is made of, for example, an elastic member such as resin, and always holds the condenser lens 14 with its elastic force. Since the resin spacer 15 is easily charged, dust and debris are likely to adhere to it. Therefore, by applying an adhesive to the inner side surface of the spacer 15, the dust and debris adhered to the inner side surface does not enter the viewfinder field of view. I am doing so. The field mask 16 is provided to mask the outside of the display area in the finder display using liquid crystal.

Next, dust countermeasures for the penta unit PU will be described.
As can be seen from FIG. 4, the space between the condenser lens 14 and the pentaprism 17 is a closed space SP surrounded by the walls of the prism box 8 on all sides, and fine dust is contained in the space SP during assembly. If it enters, the dust may adhere to the upper surface (exit surface) 14a of the condenser lens 14 or the lower surface (incident surface) of the pentaprism 17. Since these surfaces are close to the focusing screen 14, that is, the focal plane, the attached dust can be seen relatively clearly during the viewfinder observation, and the photographer may feel uncomfortable.

  Therefore, in the present embodiment, a pair of air holes 8a and 8b that communicate between the inside and the outside of the space SP are provided in the wall portion of the prism box 8 so that dust that has entered the space SP can be removed. These air holes 8a and 8b are formed at the same height position as the space SP in the wall portion corresponding to one short side of the finder screen among the four wall portions of the prism box 8 arranged in a rectangular shape. Is done. One air hole 8a functions as a hole for allowing air to flow into the space SP from the outside, and the other air hole 8b functions as a hole for discharging air from the space SP to the outside.

  When the assembly of the penta unit PU is completed at the time of camera manufacture, dust removal work is performed using, for example, an air compressor. As shown in FIG. 4, the air compressor nozzle NZ is directly opposed to the inflow air hole 8a, and air is blown into the space SP. In the present embodiment, since the air hole 8a is formed at the same height as the space SP, the high-pressure air emitted from the nozzle NZ does not hit any member and maintains the momentum while maintaining the momentum. Directly and in a straight line. In particular, since the air hole 8a is at a height position substantially equal to the upper surface (emission surface) of the condenser lens 14, high-pressure air that has not lost its momentum travels along the upper surface of the condenser lens 14 and collides with each wall portion. However, it becomes a spiral flow as shown in FIG. 5 and circulates in the space at high speed to every corner, and is gradually discharged from the air hole 8b to the outside.

  Since there are almost no places where the air flow is weak in the space SP, a large amount of dust (including dust adhering to the upper surface of the condenser lens 14 and the lower surface of the pentaprism 17) is discharged to the outside. can do. Further, as described above, if an adhesive is applied to the inner surface of the spacer 15, some dust remains adsorbed there, and does not adhere to the upper surface of the condenser lens 14 or the lower surface of the pentaprism 17. .

  Here, the portion of the space SP where the air flow rate decreases during the dust removal operation is a portion A (FIG. 6) between the air holes 8a and 8b. For this reason, the distance between the air holes 8a and 8b is preferably as short as possible. In the present embodiment, since the air holes 8a and 8b are provided in the wall portion corresponding to one short side of the finder screen among the four wall portions of the prism box 8, the interval between the air holes 8a and 8b is shortened. The portion A shown in the figure can be reduced. Further, since the air holes 8a and 8b are formed at positions close to both corners, there is no air stagnation at the corners. Therefore, effective dust removal is possible.

  Incidentally, when air holes 8a and 8b are provided in the wall portion corresponding to the long side of the finder screen as in Patent Document 1, the interval A between the holes 8a and 8b becomes longer (FIG. 7). Moreover, if the space | interval of the air holes 8a and 8b is narrowed in a long side like FIG. 8, the flow velocity of air will fall also in a corner | angular part (B part, C part), and all will reduce the dust removal effect. However, if the air holes 8a and 8b are provided at the same height position as the space SP as described above, the dust removal effect is considerably high even in the configuration of FIGS.

  After the dust removal operation, if the air holes 8a and 8b are closed with the adhesive tape 21 (FIGS. 2 and 3), the space SP becomes a substantially sealed space, and dust enters the space SP after the camera reaches the user's hand. There is nothing.

  The place where the space SP is formed is not limited between the condenser lens 14 and the pentaprism 17. Three or more air holes may be formed.

The block diagram of the digital single-lens reflex camera in one Embodiment of this invention. The perspective view which shows a penta unit and a front body. The exploded perspective view of a penta unit. Sectional drawing which looked at the penta unit from the camera front direction. FIG. 6 is a plan sectional view for explaining the flow of air in the space of the penta unit. The figure explaining that the position of the air hole in an embodiment is advantageous. The figure explaining that the position of the air hole in another example is disadvantageous. The same figure as FIG.

Explanation of symbols

8 Prism box 8a, 8b Air hole 14 Condenser lens 15 Spacer 17 Penta prism PU Penta unit SP Space

Claims (5)

In a finder device in which a plurality of optical members are stacked and held on a holding member, and a space surrounded by a wall portion of the holding member is formed between two optical members facing each other.
The wall portion of the holding member is provided with a plurality of air holes that communicate the closed space with the outside, and at least one air hole is located between the two optical members in the stacking direction of the plurality of optical members. A viewfinder device provided at the same position as the space.   2. The finder device according to claim 1, wherein at least one other air hole is provided at the same position as a space between the two optical members in the stacking direction of the plurality of optical members. In the finder device formed by holding a plurality of optical members on a holding member and forming a space surrounded by a wall portion of the holding member between two optical members facing each other.
A plurality of air holes communicating the closed space and the outside are provided in the wall portion of the holding member, and at least one air hole has a substantially straight line in the space between the two optical members. The finder device is provided at a position where it can flow into the finder.   The finder device according to claim 3, wherein at least one other air hole is provided at a position where air in the space can flow into the outside in a substantially straight line.   The camera which has a finder apparatus of any one of Claims 1-4.

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