JPH0444255B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a mirror drive mechanism of a single-lens reflex camera, and more specifically, to a movable photometric mirror used for focus detection and exposure control, for example. The present invention relates to a mirror drive mechanism for a single-lens reflex camera that moves a movable mirror to a non-photometering position in conjunction with the movement of the movable mirror.

[Conventional technology]

In a single-lens reflex camera, a movable photometric mirror 2 is provided on the back side of a movable observation mirror 1 at approximately right angles to the movable observation mirror 1, as shown in FIG. 1, for focus detection, etc. That's what I do. Before the shutter release, the movable observation mirror 1 is positioned in the photographing optical path at an angle of 45 degrees, as shown in the figure, and a portion of the light transmitted through the photographic lens 3 is transmitted to the movable observation mirror 1. 1 and is guided to the focus glass 4, pentalism 5, and finder eyepiece 6 in the viewfinder section, and some of the light passes through the half mirror section 1a of the movable observation mirror 1 and is reflected by the movable photometry mirror 2. reflect,
It is designed to be guided to a photoreceptor 7 for photometry, which is arranged at a position conjugate with the focusing glass 4 and the surface of the film 8, outside the lower photographing optical path. Focus detection and exposure control are performed based on the output of the photometric photoreceptor 7. In addition, when the shutter release moves the movable observation mirror 1 toward the focus glass 4 and retreats out of the photographing optical path, and rises to position 1A shown by the dashed line and becomes horizontal, at this time photographing is performed. The object light transmitted through the lens 3 forms an image on the film 8 and is photographed.

By the way, in this configuration, when the movable observation mirror 1 is moved to the position 1A outside the photographing optical path by the shutter release, the reverse incident light from the viewfinder eyepiece 6 is directed to the movable observation mirror 1. 1 into the photographing optical path, or the photometric movable mirror 2, which is integrated with the observation movable mirror 1, is located at the position 2A shown by the dashed-dotted line in the photographing optical path. ,
This causes problems such as blocking the subject light that has passed through the photographic lens 3.

Therefore, in order to eliminate such problems, when the movable observation mirror 1 is moved, the photometric movable mirror 2 is also moved in conjunction with the observation movable mirror 1, and when the observation movable mirror 1 is raised, A mirror drive mechanism has been proposed in which the photometric movable mirror 2 is superimposed on the observation movable mirror 1 so as to cover the half mirror portion 1a of the same mirror 1.

[Problem that the invention is trying to solve]

However, all of these conventional mirror drive mechanisms have a large number of parts and are complex in structure, and the accuracy of the detection output etc. obtained on the photoreceptor 7 by the photometric movable mirror 2 is reduced. There was a fear that this would happen.

An object of the present invention is to provide a single-lens reflex camera that has a simple configuration, has excellent detection accuracy using a photoreceptor for photometry, and that ensures light-shielding of the light-transmitting part of the movable observation mirror when taking pictures. The purpose of the present invention is to provide a mirror drive mechanism.

[Means and actions for solving problems]

In order to achieve the above object, the present invention rotates and urges the photometric movable mirror in a direction to separate it from the observation movable mirror when it is in the photometric position,
When the movable observation mirror is in the non-photometering position, a drive spring that rotates and biases the movable observation mirror in the direction of pressing the movable observation mirror so as to overlap it is passed between the movable observation mirror and the movable photometry mirror, so that the movable observation mirror is out of the photographing optical path. A cam surface that guides the movable photometry mirror toward the non-photometering position when the movable observation mirror moves back into the photographing optical path; It is set up.

The photometric movable mirror is guided and moved in conjunction with the movement of the observation movable mirror, thereby changing the biasing direction of the drive spring.

〔Example〕

Hereinafter, the present invention will be explained with reference to illustrated embodiments.

2A and 2B show a state in which the movable observation mirror of the mirror drive mechanism according to an embodiment of the present invention is lowered, and FIGS. 3A and 3B show a state in which the movable observation mirror of the same mechanism is raised. This is what is shown. The observation movable mirror 11 is attached to both side walls 1 of the mirror frame 12.
The photometric movable mirror 14 is rotatably attached to the side wall (not shown) of the mirror box by a support shaft 13 implanted in the upper end of the photometric mirror frame 15, and It is rotatably attached to the observation movable mirror 11 by a support shaft 16 provided through the side wall 12a of the mirror frame 12.

The mirror 17 of the movable observation mirror 11 is arranged parallel to the bottom plate 12b of the mirror frame 12, with a slight distance from the bottom plate 12b. That is,
One end of the mirror 17 on the side far from the support shaft 13 is
The support shaft of the mirror 17 is held between a mirror holder 18 integrally provided on the front wall 12c of the mirror frame 12 and a mirror stopper 19 whose inclined surface faces the holder 18. The other end near 13 is placed on the step of the rear wall 12d of the mirror frame 12 and is pressed toward the bottom plate 12b by a pressing spring 20 disposed through the hole 12e of the rear wall 12d. Ori,
Thereby, the mirror 17 is fixed to the mirror frame 12. A light-transmitting opening 21 is formed in a portion of the bottom plate spring 12b that faces the half mirror portion 17a of the mirror 17.
The movable photometric mirror 14 is disposed in the photometry mode. As shown in FIG. 2B, this opening 21 is opened when the photographing lens 21 is placed in a pre-photographing state in which the movable observation mirror 11 and the movable photometry mirror 14 are tilted approximately 45 degrees in opposite directions. (See FIG. 1), the opening is sufficiently larger than the total reflection mirror 22 of the photometric movable mirror 14. The mirror 22 of the photometric movable mirror 14 is fixed by direct adhesive or the like to the upper surface of the mirror support part 15b, which is made of a metal plate with strong strength and excellent flatness, and which is the bottom of the photometric mirror frame 15. A light shielding cover 23 made of a lightweight material such as plastic is fixed to the lower surface of the portion 15b. This blackout cover 2
3 extends forward from the front end of the mirror support portion 15b, and is formed in a size sufficient to cover the opening 21 in the state shown in FIG. 3B.
The rib 12f of the opening 21 comes into contact with the light shielding cover 23 when the light shielding cover 23 covers the opening 21, and serves to prevent reverse incident light from leaking into the mirror box. Although it is formed integrally with the bottom plate 12b, a relatively flexible light shielding member such as moltoprene may be attached to the same portion. The photometric movable mirror 14 has a rotation center located above the rear end of the mirror 22 so that the rear end of the mirror 22 can rotate as close to the mirror 17 of the observation movable mirror 11 as possible. Since the movable photometric mirror 14 has a supporting shaft 16 of
The mirror support portion 15 of the photometric movable mirror 14
b. To prevent the rear end of the light shielding cover 23 and the like from coming into contact with the rear edge of the opening 21 of the bottom plate 12b of the movable observation mirror 11, a gap 24 is provided between the rear end of the opening 21 and the bottom plate 12b of the movable observation mirror 11. It is formed. Therefore, in order to prevent this gap 24, a light-shielding sheet 25 whose one end is glued to a part of the bottom plate 12b near the opening 21 covers the rear end of the mirror 22, and in particular covers the movable observation mirror. 11 is raised and the photometric movable mirror 14 is also closed to cover the opening 21 of the observation movable mirror 11 (see FIG. 3B).
Reverse incident light from the viewfinder eyepiece 6 (see FIG. 1) is prevented from entering into the gap 24.

On the other hand, a substantially elliptical cam hole 26 is formed in one side wall (not shown) of the mirror box, as shown by the dashed line in FIGS. 2A and 3A. A guide pin 27 that can appropriately abut on the edge is installed at the rear of the side wall 15a of the mirror frame 15 of the photometric movable mirror 14, which faces one side wall of the mirror box. The cam hole 26 has an upper edge as a first cam surface that comes into contact with the guide pin 27 to restrict its movement when the movable observation mirror moves up, and an upper edge that serves as a first cam surface that restricts the movement of the movable observation mirror. makes contact with the guide pin 27,
A hole is formed by connecting the lower edge portion as a second cam surface that restricts the movement. This side wall 15a
The part where the guide pin 27 is fixed, that is, the rear part of the side wall 15a, completely covers the cam hole 26 when the movable observation mirror 11 is in the raised state, so that no light enters the mirror box. It has a covering portion 15c that is larger in shape than the cam hole 26. In addition, the front part of the side wall 15a covers the side part of the mirror 22, and the lower end part slightly forward of the support shaft 16 is provided when the photometric movable mirror 14 is approximately perpendicular to the observation movable mirror 11. (Refer to FIG. 2A), an escape groove 15d is formed so that rotation is not hindered by a drive spring 28, which will be described later.

The observation movable mirror 11 is driven by a known means (not shown), and the photometry movable mirror 14 is connected to the observation movable mirror 11 and the photometry movable mirror 14 in conjunction with the rotation of the mirror 11. It is driven by a drive spring 28 that is stretched between the movable mirror 14, the cam hole 26, and the guide pin 27. This drive spring 28 is
It is formed of a substantially U-shaped linear spring that applies biasing force in a direction in which both ends approach each other in the installed state. That is, the drive spring 28 is connected to the side wall 12a of the observation movable mirror 11 and the photometry movable mirror 1.
A fork formed at the lower part of the support shaft 16 of the side wall 12a of the movable observation mirror 11 is connected to the side wall 15a of the movable observation mirror 11, with both ends opened against the biasing force. Locking groove 1 of shaped protrusion 12g
2h, and the other end is attached to the movable mirror 14 for photometry.
It is locked in a locking hole 15e formed in the side wall 15a of the support shaft 16 at a position slightly diagonally above and rearward of the support shaft 16. Therefore, a tightening force always acts between the movable observation mirror 11 and the photometric movable mirror 14 between the portions where both ends of the drive spring 28 are fixed.

Next, the operation of the mirror drive mechanism according to this embodiment configured as described above will be explained in sequence with reference to FIGS. 4A to 4F. The observation movable mirror 11 is the fourth
As shown in Figure A, the same mirror 11 is in the lowered state.
The lower surface of the tip abuts against a stopper pin 29 installed in the side wall of the mirror box, and is stopped at an angle of about 45 degrees. At this time, the photometric movable mirror 14 is approximately perpendicular to the observation movable mirror 11, and in this state, the photometric movable mirror 14 has one end of the drive spring 28 connected to the support shaft 16, which is the rotation center. Since it is located to the left of the straight line passing through the movable observation mirror 11 and the other end of the drive spring 28, it is biased to rotate counterclockwise with respect to the movable observation mirror 11. It collides with the stopper roller 30 and stops. In addition, in this state, the photometric movable mirror 14
The upper guide pin 27 is located away from the operating cam edge of the cam hole 26 and is not regulated by the cam hole 26.

Photometry is performed in the above state, and focus detection, exposure control, etc. are performed. When the shutter is released, the movable observation mirror 11 begins to rotate clockwise about the support shaft 13 by known means. Even if this movable observation mirror rotates slightly clockwise as shown in FIG. 4B and separates from the stopper pin 29, the drive spring 28
The photometric movable mirror 14, which is biased with a rotational force in the counterclockwise direction by are doing.

When the guide pin 27 reaches the position where it is regulated by the upper edge of the cam hole 26, from this point on, the photometric movable mirror 14 is biased with a counterclockwise rotational force by the drive spring 28. As shown in FIG. 4C, when the observation movable mirror 11 further rotates clockwise, the guide pin 27 of the photometry movable mirror 14 touches the upper edge of the cam hole 26. Since the photometric movable mirror 14 is regulated and guided according to the shape of the press-contact cam hole 26, at this time, the photometric movable mirror 14 is separated from the stopper roller 30 and rotated clockwise relative to the observation movable mirror 11.

Further, the mirror 11 rotates clockwise and rises, and the photometric movable mirror 14 also reaches a position where both ends of the drive spring 28 and the support shaft 16 are aligned in a straight line, as shown in FIG. 4D. The guide pin 27 rotates clockwise against the biasing force of the drive spring 28 while being regulated and guided by the upper edge of the cam hole 26. Then, as shown in FIG. 4D, the drive spring 2
8 and the support shaft 16 are aligned in a straight line, that is, the spring 28 exceeds the consideration point, and one end of the spring 28 passes through the support shaft 16 and the other end of the drive spring 28. When the position is to the right of the straight line,
At this time, the photometric movable mirror 14 is moved by the drive spring 28.
The biasing direction is switched, and a biasing force that rapidly rotates clockwise about the support shaft 16 is applied. Therefore, at this time, the guide pin 27 separates from the upper edge of the cam hole 26 and traverses approximately the center of the cam hole 26 along a trajectory as shown by the dotted arrow B, and the guide pin 27 moves away from the upper edge of the cam hole 26 as shown in FIG. 4E. The photometric movable mirror 14 is rotated largely clockwise relative to the observation movable mirror 11 until it reaches a position where it abuts the lower edge of the cam hole 26.

The guide pin 27 abuts the lower edge of the cam hole 26,
When the photometric movable mirror 14 reaches a rotational position almost parallel to the observation movable mirror 11 as shown in FIG. The amount of rotation is regulated. When the observation movable mirror 11 further rotates clockwise around the support shaft 13 and rises, the photometry movable mirror 14 is movable for observation with the guide pin 27 being regulated and guided by the lower edge of the cam hole 26. It rotates clockwise around the support shaft 16 in a direction parallel to the mirror 11 and rises.

When the movable observation mirror 11 further rotates clockwise and reaches the fully raised position as shown in FIG. Becomes polymerized. That is, at this point, the photometric movable mirror 14
, the guide pin 27 goes from being in contact with the lower edge of the cam hole 26 to being slightly separated from the lower edge of the cam hole 26, so that the clockwise urging force by the drive spring 28 acts on the photometric movable mirror 14 again, and the mirror 14 The light-shielding cover 23 is attached to the light-shielding rib 1 of the movable observation mirror 11.
2f and stops rotating in a state where the light-transmitting opening 21 of the movable observation mirror 11 is closed. In this state, the subject light transmitted through the photographing lens 3 is projected onto the film 8 via the shutter, and photographing is performed (see FIG. 1). In this shooting condition,
The reversely incident light from the viewfinder eyepiece 6 is transferred from the photometric movable mirror 14 to the observation movable mirror 11.
Since the opening 21 of the mirror is completely closed, there is no possibility that the light will enter the mirror box.

In this way, as the observation movable mirror 11 is rotated to the raised position, the photometry movable mirror 14 is
The guide pin 27 moves the cam hole 26 along a trajectory 31 shown in FIG. 5A. That is, the guide pin 27 is located at the position P ₁ of the cam hole 26 shown in FIG. 4A.
After reaching the position _P2 where it contacts the upper edge of the cam hole 26 as shown in FIG. The movable mirror 14 for photometry is guided to the state of P ₃ , and after this point, the movable mirror 14 for photometry is moved around the pivot axis by the action of the drive spring 28.
1, the guide pin 27 reaches a position _P4 where it touches the lower edge of the cam hole 26 as shown in FIG. 4E. At this time, the guide pin 27 slides into contact with the lower edge of this cam hole 26 and reaches position _P5 .
When the guide pin 27 reaches this position P ₅ , the movable photometric mirror 14 rotates clockwise relative to the movable observation mirror 11 , and the opening 21 of the movable observation mirror 11 is rotated clockwise relative to the movable observation mirror 11 . It is completely covered with the light shielding cover 23. From this state, when the guide pin 27 separates from the lower edge of the cam hole 26 and reaches the initial position P ₁ , the movable observation mirror 11 rotates clockwise around the support shaft 13 together with the movable photometry mirror 14. move. Guide pin 27 is at position P ₁
In this state, the mirror 11 rises horizontally as shown in FIG. 4F, and this movable observation mirror 1
The movable photometric mirror 14 whose opening 21 is closed by a light-shielding cover 23 is not subjected to any regulating force from the guide pin 27, but is subjected to a clockwise rotation biasing force from a drive spring 28. The observation movable mirror 1 is not restricted by the hole 26 where the photographing ends.
1, the cam rotates largely counterclockwise around the support shaft 16, and at position P ₉ →P ₁₀ , the cam rotates around the support shaft 16 against the large counterclockwise biasing force of the drive spring 28. Perform counterclockwise rotation regulated by the upper edge of hole 26, and finally at position P ₉ →P ₁₀ , cam hole 2
6, but is regulated by the stopper roll 30 to which a rotational bias force is applied in the counterclockwise direction around the support shaft 16, so that an accurate angular position with respect to the movable observation mirror 11 is maintained. ing.

〔effect〕

As described above, according to the mirror drive mechanism of the present invention, in the photometry position, the movable photometry mirror is urged in a direction away from the movable observation mirror and pressed against the stopper, so that the position of the movable photometry mirror is adjusted. Since it is accurately determined by the stopper and is pressed against the movable observation mirror so as to be superimposed in the non-photometering position, the light-transmitting portion of the movable observation mirror can be reliably shielded from light. Furthermore, the configuration is simple, and the movable observation mirror 11 and photometry movable mirror operate in the opposite manner to the above, and the movable observation mirror 11 does not require troublesome adjustment work, as shown in FIGS. It descends again to an angular position of approximately 45 degrees, and the movable photometric mirror 14 also maintains a state approximately perpendicular to the movable observation mirror 11. When the observation movable mirror 11 rotates counterclockwise about the support shaft 13 when descending, the photometry movable mirror 14 is moved so that the guide pin 27 moves the cam hole 26 into the fifth position.
A movement is performed to draw a trajectory 32 shown in Figure B.
That is, as the observation movable mirror 11 rotates downward, the guide pin 27 of the photometry movable mirror 14 moves in the cam hole 26 from P ₆ (P ₁ ) → P ₇ → P ₈ → P ₉ → P ₁₀ . do. The photometric movable mirror 14 moves integrally with the observation movable mirror 11 around the support shaft 13 from position P ₆ (P ₁ ) to P ₇ in the above-mentioned trajectory 32.
At P ₇ →P ₈ , rotation is made in the counterclockwise direction, regulated by the descent of the cam hole 26, about the support shaft 16 against the clockwise rotational biasing force of the drive spring 28, and the position
At P ₈ →P ₉ , the direction of the rotational biasing force by the drive spring 28 is switched, and the cam is not required. The spring that provides the driving force to the photometric movable mirror is not connected to a fixed base plate such as a mirror box, but rather to the movable observation mirror, so the operating state of the photometric movable mirror can be determined before it is incorporated into the camera. This can be confirmed, improving work efficiency during assembly.

[Brief explanation of drawings]

Fig. 1 is a schematic cross-sectional view of a single-lens reflex camera to which the mirror drive mechanism of the present invention is applied, and Fig. 2A
3A and B are side views and cross-sectional views of the mirror drive mechanism shown in one embodiment of the present invention in the mirror lowered state, and FIGS. 3A and B are side views of the mirror drive mechanism shown in FIG. 2 above in the mirror raised state. and sectional views, and FIGS. 4A to 4F are side views and FIGS.
and B are diagrams illustrating the locus of the guide pin in the cam hole when the mirror is raised and lowered in the mirror drive mechanism shown in FIG. 2 above. 1, 11...Movable mirror for observation, 2, 14...
Movable mirror for photometry, 3...Photographing lens, 26...
Cam hole, 27...guide pin, 28...drive spring.

Claims (1)

[Scope of Claims] 1. A light-transmitting portion that is movably provided with respect to a fixed base plate such as a side wall of a mirror box, that guides light that has passed through the photographic lens to the viewfinder portion, and that transmits a portion of the light. a movable observation mirror having a movable observation mirror; and a movable observation mirror that is rotatably supported on the movable observation mirror so as to guide the light that has passed through the photographic lens and the light-transmitting part to the photoreceptor for photometry. a photometric movable mirror that changes between a photometric position in which it is spaced apart and a non-photometric position in which it overlaps with the observation movable mirror so as to cover the light-transmitting portion; the photometric movable mirror abuts in the photometric position; A stopper for regulating the photometric position of the mirror is arranged in a plane substantially perpendicular to the rotating axis of the movable photometric mirror, and is formed in a substantially annular shape that bypasses the rotating axis, and has two functions. The dot extends between the observation movable mirror and the photometry movable mirror at a position substantially across the rotational axis, and in the photometry position, the photometry movable mirror is separated from the observation movable mirror in a first direction. In the non-photometering position, the movable mirror for photometry is pressed in a second direction so as to overlap with the movable observation mirror, and in the photometering position and the non-photometering position, the movable mirror for photometry is pressed against the movable mirror for photometry in the non-photometering position. a drive spring for switching the direction of the biasing force; an engagement member provided on either one of the fixed base plate and the photometric movable mirror; When retracting out of the photographing optical path, it cooperates with the engaging member to guide the photometric movable mirror to a non-photometric position, and changes the direction of the biasing force of the drive spring from the first direction to the first direction. a first cam surface that is changed in the second direction; and when the movable observation mirror moves back into the photographing optical path, the movable observation mirror cooperates with the engagement member to guide the movable photometry mirror to a photometry position; a second direction for changing the direction of the biasing force of the drive spring from the second direction to the first direction;
A mirror drive mechanism for a single-lens reflex camera, comprising: a cam having a cam surface; and a cam surface.