JPH0214031Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is directed to a focusing screen alignment device, specifically, to a single-lens reflex camera equipped with a focusing screen having an index for displaying the focusing position or spot photometry position. The present invention relates to a focusing screen alignment device in which the above-mentioned index corresponds to a photometric light receiving section.

In a single-lens reflex camera equipped with an automatic focusing device, as shown in FIG. The light reflected upward by the half mirror 3 travels along the optical path 1b in a direction perpendicular to the optical axis 1a of the photographic lens 1, and the pentaprism 7 is supported above the movable mirror frame 2. A mounting plate 4 and mounting screws 5 are attached to the fixed parts 13a and 13b of the main body 13.
The image is formed on a focusing screen 6 which has an index 6a for displaying the focus position in the center, which is fixed horizontally by a ), the light transmitted through the half mirror 3 passes through the opening 8 of the movable mirror frame 2, is reflected by the distance measuring mirror 9, and travels downward as shown by the optical path 1c for distance measurement. The light is guided to the light receiving element 10 for use.

Incidentally, the distance measuring light receiving element 10 and the focusing screen 6 must be arranged in a conjugate positional relationship. However, since the positions of the two may deviate greatly from the predetermined positions due to accumulated errors in assembling the camera, an adjustment mechanism for alignment after assembly is required. Therefore, conventionally, the distance measuring light receiving element 10 is adjusted for deviations in the optical path length direction (Z direction), and also for deviations in the front and back direction of the camera, that is, in the vertical direction (X direction) of the screen. The distance measuring mirror 9 was being adjusted. That is, the light receiving element 10 has an electric wiring board 12 fixed to a metal plate 11.
Since the metal plate 11 is attached to the camera body 13 with a screw 15 via a coil spring 14, the height position of the light receiving element 10 can be adjusted by rotating the screw 15 clockwise or counterclockwise. This allows the optical path length in the Z direction to be adjusted. Further, the mirror frame 16 of the distance measuring mirror 9 opens at a substantially right angle to the half mirror 3.
Since the adjustment eccentric cam 17 is provided in contact with the center of the focusing screen 6, the beam passes through the half mirror 3 corresponding to the optical path 1b passing through the index 6a at the center of the focusing screen 6, and is set at a nearly right angle by the distance measuring mirror 9. If the optical path 1c of the light reflected in the direction is shifted from the center of the light receiving element 10, the eccentric cam 17 is appropriately rotated in the direction of the arrow, and the cam 17 is pressed against the cam 17 by a biasing means (not shown). The mirror frame 16 of the distance measuring mirror 9 is rotated in the same direction to tilt the optical path 1c to form an optical path 1d, so that the light corresponding to the index 6a is incident on the center of the light receiving element 10. Ta.

However, in the above-mentioned conventional alignment adjustment mechanism, although there is no problem with the adjustment in the Z direction, in the adjustment in the X direction, the inclination angle of the distance measuring mirror 9 is changed, so that the reflected optical path 1d is tilted with respect to the light-receiving element 10, making it impossible to perform proper distance measurement. In order to perform proper distance measurement, the light incident on the light receiving element 10 must be kept perpendicular to the light receiving surface of the light receiving element 10, as in the optical path 1c.

In view of the above-mentioned conventional problems, the purpose of the present invention is to ensure that the index for displaying the focus position or spot photometry position of the focusing screen corresponds to the light receiving part for distance measurement (light receiving part for photometry). for,
This is a focusing system that supports the focusing screen so that it can be adjusted horizontally without changing the inclination angle of the distance-measuring mirror (photometering mirror) as in conventional systems, and adjusts this as appropriate. The present invention provides a casing screen alignment device.

The present invention will be explained below based on the illustrated embodiments.

FIG. 2 is a sectional view of a focusing screen alignment device showing an embodiment of the present invention. In FIG. 2, a fixing part 13a supporting the pentaprism 7 of the main body 13, 13b
The same screen 6 is attached to the position regulating member 18 fixed to the
The upper surfaces of both the front and rear edges of are brought into contact with each other. The focusing screen 6 is supported by the position regulating member 20a of the position adjusting member 19 attached to the fixing part 13a at the front thereof, and by the supporting piece 22 attached to the fixing part 13b at the rear thereof. 18 and held horizontally at a position conjugate with the film surface. Further, while the focusing screen 6 is held at the above-mentioned predetermined position, the focusing screen 6 is moved horizontally (back and forth) by the position adjustment member 19 provided in front of the screen 6 and the elastic member 23 provided in the rear fixed portion 13b. It is now possible to adjust the movement (direction).

To explain the above configuration in detail, the position adjustment member 19 is a plate member 2 formed by cutting out a single metal plate having relatively elastic force, as shown in FIG.
0 and an adjustment screw 21, and the plate member 20 includes:
Three plate pieces 20a, 20b, 20a are lined up in a fork shape and extend horizontally in one direction, and at the connecting part of these plate pieces, the plate pieces protrude to the opposite side from the plate pieces and are bent upward at a right angle. A mounting portion 20c having a mounting hole for the adjustment screw 21 is integrally formed. The three plate pieces 20a,
Of the plates 20b and 20a, the central plate piece 20b is bent at a right angle with its tip facing upward, and serves as a positioning piece for pressing one end surface of the focusing screen 6. Moreover, this positioning piece 20b
The two plate pieces 20a on both sides of the same positioning piece 2
0b, and its tip is bent upward at a right angle, and then bent at a right angle in the horizontal direction to serve as a support piece for supporting the focusing screen 6.

The position adjustment member 19 has a front fixed portion 13a.
Place the horizontal part of the plate member 20 on the lower surface of the plate member 20 with the mounting portion 20c facing forward, and
The adjustment screw 21 is attached to the attachment portion 20c of the fixing portion 13a, and the adjustment screw 21 is screwed into a screw hole provided at a predetermined position of the fixing portion 13a. As is clear from FIG. 3, the front end surface of the fixed portion 13a can be seen from the front when the lens barrel of the camera 31 is removed. Since this is the upper edge facing the opening 33 of the lens mount 32, at this time, the mounting portion 20c of the plate member 20 is attached at the same position.
Then, the adjustment screw 21 is exposed to the front. By attaching the position adjustment member 19 to the fixed part 13a, the tip of the positioning piece 20b faces the front end surface of the focusing screen 6, and the tip of the support piece 20a faces the front edge of the focusing screen 6. It supports the same part by coming into contact with it from the bottom surface. The support piece 20a is slightly bent by supporting the focusing screen 6, but the support piece 20a is prevented from bending beyond a certain level.
A reinforcing member 24 that maintains a pressure contact force for securely holding the focusing screen 6 between the position regulating member 18 and the position regulating member 18 is attached to the horizontal portion of the plate member 20 by screws 25 on the lower surface of the fixing portion 13a. It is attached by sandwiching it.

The support piece 22 supporting the rear edge of the focusing screen 6 is formed by bending an elastic metal plate, and its base is attached to the lower surface of the fixing part 13b with screws 26. At this time, the tip comes into contact with the lower surface of the focusing screen 6, and its restoring elasticity causes the rear end edge of the focusing screen 6 to come into pressure contact with the position regulating member 18, thereby supporting the same portion.

Then, the fixed part 1 is placed at the same height position as the focusing screen 6 supported at the predetermined position.
3b in the front-rear direction, that is, the optical axis 1 of the photographic lens 1.
A through hole 27 parallel to a is bored, and a coil spring 28 and a pressing pin 29 that constitute the elastic member 23 are loosely fitted into this through hole 27. Focusing screen 6 of through hole 27
Since the opening on the far side is closed by the fixing stopper 30, the pressing pin 29 is pushed against the focusing screen 6 by the tension of the coil spring 28 interposed between the pin 29 and the fixing stopper 30. It has been given the habit of moving toward the target. Therefore, the focusing screen 6 is always given an urging force directly by the pressing pin 29 of the elastic member 23 to move in the direction of the arrow Xa, that is, forward. A positioning piece 20b of the position adjustment member 19 described above is provided on the front end surface of the focusing screen 6.
are facing each other, so the front end surface of the focusing screen 6, which is constantly pushed in the Xa direction by the pressing pin 29, comes into contact with the positioning piece 20b, so that the screen 6 is stabilized in that position. and remain stationary.

If it is desired to shift the focusing screen 6 in the front-back direction, this can be accomplished by turning the adjustment screw 21 of the position adjustment member 19. For example, when the adjustment screw 21 is turned clockwise, the screw 21 becomes more deeply engaged with the fixing portion 13a, and the plate member 20 also moves rearward at the same time. The focusing screen 6 in contact with the coil spring 20b moves in the direction opposite to the direction of the arrow Xa while pushing back the pressing pin 29 against the tension of the coil spring 28. Furthermore, when the adjusting screw 21 is turned counterclockwise, the screw 21 moves in a direction to shallower the degree of screwing into the fixing part 13a, and as a result, the plate member 20 also moves forward at the same time. Therefore, contrary to the above case, the focusing screen 6 is moved by the positioning piece 20 by the tension force of the coil spring 28.
It moves in the direction of arrow Xa while contacting b. In this way, when the focusing screen 6 moves in the direction of the arrow Xa or the opposite direction by adjusting the position adjusting member 19, the focusing screen 6 is always moved by the position regulating member 1 by the support pieces 20a and 22.
Since the screen 6 is supported so as to be in pressure contact with the film surface, the screen 6 is reliably moved in the horizontal direction to a position conjugate with the film surface.

By the way, among the light transmitted through the photographic lens 1, the light reflected by the half mirror 3 is directed toward the optical axis 1 of the photographic lens 1.
Proceed upward along the optical path 1b at right angles to a. Also,
Since the distance measuring mirror 9 is adjusted to an angle perpendicular to the half mirror 3 by the adjustment eccentric cam 17 in contact with the mirror frame 16, the half mirror 3
The transmitted light is reflected by the distance measuring mirror 9 and travels down an optical path 1c at right angles to the optical axis 1a of the photographing lens 1. However, due to integration errors in camera assembly, the position of the indicator 6a for displaying the focus position on the focusing screen 6 and the position of the distance measuring light receiving element 10 often do not correspond accurately, and the second In the figure as well, the optical path 1b passes through the index 6a, while the optical path 1c corresponding to this optical path 1b is slightly shifted by a distance A from the center of the distance measuring light receiving element 10. Therefore, in this state, the actual focus position and the focus position displayed by the indicator 6a on the focusing screen 6 viewed from the viewfinder eyepiece will not match.

Therefore, as is clear from FIG. 2, the light directed toward the focusing screen 6 at the position of the index 6a for displaying the focus position is received on the optical path 1c 1 shifted by a distance A in the direction of arrow Xb from the optical path _1c . Element 1
It can be seen that this corresponds to the light incident on the central part of 0.

Further, the optical path toward the focusing screen 6 corresponding to the optical path 1c ₁ is an optical path 1b 1 which is an optical path 1a _{1 separated by a distance A from the optical axis 1a of the photographic lens 1} and branched into an optical path 1c ₁ by a half mirror _3. It is. Therefore, when the adjustment screw 21 of the position adjustment member 19 is rotated counterclockwise, the screw 21 and the plate member 20 are moved forward, that is, as indicated by the arrow Xa, as described above.
Therefore, the focusing screen 6 is pushed by the pressing pin 29 and moves in the direction of the arrow Xa. When the focusing screen 6 is adjusted and moved by the distance A in the direction of the arrow Xa using the position adjustment member 19, the index 6a is moved along the optical path 1b ₁
The light reaches the position where it enters the focusing screen 6, and corresponds to the center of the distance measuring light receiving element 10.

Therefore, after assembling the camera, the position adjustment member 1
9 to adjust the focusing screen 6 as described above, the in-focus position on the focusing screen 6 seen through the viewfinder eyepiece corresponds accurately to the in-focus position during actual distance measurement. can be done. This adjustment operation of the position adjustment member 19 can be easily performed from the front of the camera 31 at the opening 33 of the lens mount 32.

If there is a deviation in the optical path length direction between the focusing screen 6 and the distance measuring light receiving element 10, the light receiving element 10 can be adjusted in the Z direction by rotating the screw 15 in an appropriate direction. The setting at a position conjugate with the casing screen 6 is the same as described in FIG.

Further, in the above embodiment, the index 6a was described as being for displaying the focus position, but it can also be used for displaying the spot photometry position.

As described above, according to the present invention, the focusing screen can be adjusted in the horizontal direction, so that it can be used to display the focus position or spot photometry position, which is caused by errors in camera assembly. The position of the index can be made to correspond accurately to the light receiving section for photometry, so that the actual focus position of photometry and the focus position of observation light match, and accurate photometry can be performed. Further, the structure is simple, the adjustment operation can be performed reliably, and the adjustment operation is extremely easy.

[Brief explanation of the drawing]

Fig. 1 is an enlarged sectional view of the main parts of a single-lens reflex camera equipped with a conventional positioning mechanism for adjusting the focus position, and Fig. 2 is a focusing screen showing an embodiment of the present invention. FIG. 3, an enlarged sectional view of the alignment device, is a perspective view of the main parts of the alignment device shown in FIG. 2 above. 1...Photographing lens, 3...Half mirror (movable mirror for observation), 6...Focusing screen, 6a...Indicator for displaying the focus position, 9...Mirror for distance measurement (mirror for photometry), 10...Light-receiving element for distance measurement (light-receiving part for photometry), 18...Position regulating member,
19...Position adjustment member, 23...Elastic member.

Claims (1)

[Scope of Claim for Utility Model Registration] An indicator is provided on the focusing screen to indicate the position corresponding to the light receiving section for photometry, and the light transmitted through the photographic lens is guided to the light receiving section for photometry and the focusing screen. a single-lens reflex camera, comprising: a holding means for supporting the focusing screen in a state in which it can be adjusted and moved within a plane perpendicular to the optical axis;
a position adjustment member for adjusting the position of the focusing screen in a plane perpendicular to the optical axis, and the index of the focusing screen is made to correspond to the photometric light receiving section. Focusing screen alignment device.