JP3326944B2 - Camera mirror bounce prevention device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mirror preventing device for a single lens reflex camera.

[0002]

2. Description of the Related Art The present inventor has already proposed, in Japanese Patent Application No. 5-199117, an apparatus for preventing a mirror of a single-lens reflex camera from bounce. First, a description will be given of a bounce prevention device for a mirror for a single-lens reflex camera proposed by the present inventors, with reference to FIGS.

In FIG. 2, an object mA is rotating around an axis A at an angular velocity vector ωA. Object mB is axis B
Is rotated around the angular velocity vector ωB. Now, with the axis A as the origin, the X axis is taken in the direction from the axis A to the axis B, and the Y axis is taken in a direction perpendicular to this. Further, the direction perpendicular to the plane of FIG. 2 is taken as the Z axis. The moment of inertia of the object mA is represented by IA, and the moment of inertia of the object mB is represented by IB. A common normal at the point Pc when the object mA and the object mB collide at the point Pc is defined as a line QQ. The direction cosine of the line QQ is represented by a vector λ. The impulse acting on the object mA due to the collision is defined as a vector ∫F2dt, and the impulse acting on the object mB is defined as a vector ∫F1dt. Position vector rAP, r
BP, rB and each component are as shown in FIG.

[0004] The law of conservation of angular momentum is applied to the object mA. IAωA + rAP × ∫F2dt = IAωA ′ (1)

[0005] The law of conservation of angular momentum is applied to the object mB. IBωB + rBP × ∫F1dt = IBωB ′ (2) where ωA ′ and ωB ′ represent angular velocity vectors after collision of the object mA and the object MB, respectively.

FIG. 2 shows that the position vectors rAP, rBP, rB
, RBP = rAP−rB (3) holds.

At the point Pc, the law of action and reaction is applied.

∫F1dt = −∫F2dt (4) In the object mA and the object mB before the collision, the λ-direction component of the velocity at the point Pc is represented by ( va) λ and (vb) λ. In the objects mA and MB after the collision, the λ-direction components of the velocity at the point Pc are represented by (va) λ ′ and (vb) λ ′. If the coefficient of restitution at the point Pc is e, then the following holds: e = [(vb) λ ′ − (va) λ ′] / [(va) λ− (vb) λ] (5)

Here, (va) λ = (ωA × rAP) · λ (6) (vb) λ = (ωb × rbP) · λ (6) … (7) (va) λ ′ = (ωA ′ × rAP) · λ (8) (vb) λ ′ = (Ωb ′ × rbP) · λ (9)

When the Z-axis direction components ωAZ ′ and ωBZ ′ of the angular velocity vectors ωA ′ and ωB ′ are obtained using the equations (1) to (9), Becomes

Here, C1 = −ypλx + (xp−xB) λy (12) C2 = −ypλx + xλy (12) 13)

In equation (10), it is assumed that the object mB is stopped before the collision, and the object mA is stopped after the collision. If this happens, ωBZ = ωAZ' = 0 because it is ^{················ (14), C1 2 IA} = e C2 2 IB ········· (15)

That is, if the equation (15) holds, the object mA moving before the collision stops due to the collision.

Considering the object mA as a member on the main mirror holding frame 2 side, and regarding the object mB as a member on the main mirror receiver 22 side,
It can be seen that if the design is made to substantially satisfy the equation (15), a bounce prevention device can be obtained.

In FIG. 3, the main mirror 1 of the single-lens reflex camera is at a position where the subject can be observed through a finder (not shown). The main mirror 1 has a semi-transmissive portion 1 a and is fixed to the main mirror holding frame 2. 3 and 4 are support members, which are integrated with the main mirror holding frame 2. The shafts 5 and 6 and the pin 7 are fixed to the support member 3.
The shafts 8 and 9 and the pin 10 are fixed to the support member 4. The shafts 5 and 8 are rotatably supported by a camera body (not shown), and their center lines are both LL lines. The sub mirror 11 is fixed to a sub mirror holding frame 12. Reference numerals 13 and 14 denote sub-mirror support members, which are integrated with the sub-mirror holding frame 12. The sub-mirror support member 13 is rotatably supported around the shaft 6.
The pin 15 is fixed to the sub mirror support member 13.
A toggle spring 16 is hung between the pin 15 and the pin 7.

The sub-mirror support member 14 is rotatably supported around the axis 9. The center lines of axes 6 and 9 are both MM lines. Shafts 17 and 18 and pins 19 and 20
Are fixed to a camera body (not shown). Eccentric pin 2
Reference numeral 1 is attached to a camera body (not shown) so that rotation can be adjusted. The main mirror receiver 22 and the inertia lever 23 are both mounted rotatably around the axis 18. Since both ends are connected by the pin 24, they move together. The arm 22a of the main mirror receiver 22 is in contact with the eccentric pin 21, and one end of a spring 26 is attached to the tip thereof.

The pin 25 is fixed to the main mirror receiver 22, and the tip is in contact with the main mirror holding frame 2. The inertial lever 23 has an arc-shaped friction surface 23a,
Is attached. The brake lever 28 is rotatably mounted around the shaft 17, has a contact surface 28a,
A pin 29 is fixed to the tip. The other end of the spring 26 is hung on this pin 29. The spring 26 urges the main mirror receiver 22 counterclockwise around the shaft 18 and urges the brake lever 28 clockwise around the shaft 17. With this urging force, the arm 22a is pressed against the eccentric pin 21, and the contact surface 28a is pressed against the friction surface 23a. The mirror return spring 30 has one end fixed to the pin 7 and the other end fixed to a camera body (not shown). The main mirror 1 is urged counterclockwise around the axes 5 and 8 by the mirror return spring 30. With this biasing force,
The main mirror holding frame 2 is pressed against a pin 25.

The spring 26 has a stronger biasing force than the mirror return spring 30. The drive lever 31 is attached to a camera body (not shown). The pin 10 is within the movement trajectory of the drive lever 31.

When a release button (not shown) is pressed, the drive lever 31 moves in the direction G in FIG. 3 and engages with the pin 10 to raise the main mirror 1. At this time, the main mirror 1 rotates clockwise around the shafts 5 and 8 against the mirror return spring 30. When the sub-mirror holding frame 12 and the pin 20 are brought into a non-contact state, the mirror supporting member 13 is turned on by the toggle spring 16.
The arm 13a of the mirror supporting member 13 and the pin 19 are brought into contact with each other by rotating the arm 13a counterclockwise around the axis 6 by the urging force of the above. When the main mirror 1 is further moved up, the pin 15 comes to the opposite side to that of FIG. 3 with respect to the line connecting the axis 6 and the center of the pin 7.

Then, the biasing force of the toggle spring 16 acts to rotate the mirror support member 13 clockwise around the axis 6. As a result, the arm 1 of the mirror support member 13 is
3b and the pin 19 come into contact with each other. When the main mirror 1 completes ascending, as shown in FIG. 5, the main mirror 1 comes into contact with a stopper 33 fixed to the camera body and stops. At this time, the sub-mirror holding frame 12 and the main mirror holding frame 2 come into contact with each other by the biasing force of the toggle spring 16, and the semi-transmissive portion 1a is shielded from light. Thereafter, when the main mirror 1 reaches the photographing position and stops, a shutter (not shown) operates to perform exposure. After the exposure is completed, the drive lever 31 moves in the direction opposite to G in FIG. Following this, the main mirror 1 is moved to the mirror return spring 30.
Rotates counterclockwise around axes 5 and 8 by the urging force of, and returns to the observation position.

FIG. 4 shows that the main mirror 1 is lowered and the pins 2
5 shows a moment when the main mirror 5 and the main mirror holding frame 2 collide.
Here, since the weight 27 is attached between the member on the main mirror side and the member on the main mirror receiving side so that the expression (15) is substantially satisfied, the member on the main mirror side is almost stopped after the collision, and the main mirror is stopped. The receiving member will rotate clockwise about axis 18. The members on the main mirror side include all members that move when the main mirror 1 returns to the observation position by the biasing force of the mirror return spring 30 (that is, members corresponding to the object mA in FIG. 2). The main mirror receiving side member includes all members that move by the impact force received by the pin 25 due to the collision (that is, the member corresponding to the object mB in FIG. 2).

The kinetic energy obtained by the main mirror receiving member due to the collision is stored as distortion energy of the spring 26, and is dissipated by friction between the contact surface 28a and the friction surface 23a. Eventually, the main mirror receiving side member stops rotating clockwise, and now starts to rotate counterclockwise by the urging force of the spring 26. Then, the pin 25 and the main mirror holding frame 2 make a second collision. At this time, the friction between the contact surface 28a and the friction surface 23a causes
The kinetic energy of the main mirror receiving member is sufficiently dissipated. Therefore, the main mirror side member hardly bounces.

FIG. 5 shows the result of an experiment performed on an actual camera. In the experiment, of the light S1 passing through the lens (not shown) shown in FIG.
Is observed by using the photometric distance measuring means 32. When the bounce after the mirror down is settled, the light S3 toward the photometric distance measuring means 32
Therefore, the output of the photometric distance measuring means 32 is also stabilized.
Therefore, the time required for the output of the photometric distance measuring means 32 to stabilize is regarded as the bound time after the mirror-down, and is plotted on the vertical axis in FIG. The horizontal axis represents the moment of inertia of the main mirror receiving member. The fixed time indicated by the broken line in the figure represents the bound time when the main mirror receiving side member is fixed to the camera body. In the experiment, the light S3 is not necessarily measured, but the light S2 reflected by the main mirror may be measured by the photometric distance measuring means 32 'on the finder side.

In FIG. 4, when the eccentric pin 21 is rotated to adjust the position of the main mirror 1 by 45 °, the common normal PP at the collision point between the pin 25 and the main mirror holding frame 2 also changes. Then, C shown in equations (12) and (13)
The values of 1 and C2 also change, and an error occurs in the conditional expression (15) for preventing bouncing. Therefore, in the bounce prevention device for a single-lens reflex camera mirror disclosed in Japanese Patent Application No. 5-199117, in order to correct this error, the inertia moment is adjusted by adjusting the weight of the weight 27, for example.

[0031]

However, with the device for preventing the bounce of a mirror for a single-lens reflex camera disclosed in Japanese Patent Application No. 5-199117, adjustment is made so that the bounce prevention effect is maximized (around the Bmin point in FIG. 5). To do so, the position of the main mirror holding frame 2 is adjusted, and then the moment of inertia is adjusted (such as adjusting the weight of the weight 27). That is, there is a problem that two adjustments are required, and the adjustment work becomes complicated.

The present invention has been made in view of such a situation, and eliminates the need for adjusting the moment of inertia.
An object of the present invention is to reduce the number of parts and facilitate the adjustment of the camera assembly, thereby reducing the cost.

[0033]

According to a first aspect of the present invention, there is provided a mirror member capable of reciprocatingly rotating between an observation position and a photographing position, and rotating when a mirror member collides. A mirror receiving member for regulating the position of the mirror member at a predetermined rotation angle, and a braking member for braking relative movement of the mirror receiving member with respect to the camera body, The configuration is such that the shape of the portion where the mirror member and the mirror receiving member collide is an involute curve.

According to a second aspect of the present invention, there is provided a mirror member which is reciprocally rotatable between an observation position and a photographing position; a mirror member which rotates when a collision occurs to absorb the angular momentum of the mirror member; It has a mirror receiving member for regulating the position at a predetermined rotation angle, and a braking member for braking the relative movement of the mirror receiving member with respect to the camera body. , Each of which is configured to be an approximate arc of an involute curve.

According to a third aspect of the present invention, there is provided a mirror member capable of reciprocatingly rotating between an observation position and a photographing position; a mirror member which rotates when a collision occurs to absorb the angular momentum of the mirror member; It has a mirror receiving member for regulating the position at a predetermined rotation angle, and a braking member for braking the relative movement of the mirror receiving member with respect to the camera body. , Each of which is a polygonal line approximating an involute curve. According to a fourth aspect of the present invention, in the first to third aspects, the involute curve is a tooth shape of a pair of involute gears meshing with the rotation center of the mirror member and the rotation center of the mirror receiving member as the rotation center. .

[0036]

In the camera mirror bouncing prevention device having the above-described structure, the shape of the collision portion between the mirror member and the mirror receiving member is an involute curve or an approximate curve thereof. Since the common normal at the point hardly changes, the condition for preventing bouncing hardly changes. Therefore, even if the position of the mirror member is adjusted, there is almost no error in the condition for preventing the bounce, and the inertia moment adjusting device and the adjusting operation for correcting this error can be omitted.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Prior to that, the principle of a camera mirror bounce prevention device according to the present invention will be described with reference to FIG.

In FIG. 2, the equation of the common normal QQ will be obtained.

I) The inclination of the QQ line from the direction cosines λx and λy is λy / λx.

Ii) The point Pc (xp, yp) is on the QQ straight line.

From the above, the equation of the QQ line is

Y = (λy / λx) x + yp− (λy / λx) xp (100)

Here, an arbitrary point P0 (x
0, y0)

Y0 = (λy / λx) x0 + yp− (λy / λx) xp (101)

The collision point between the objects mA and mB is changed from Pc to P0.
When the value of equation (12) is changed to

C01 = −y0λx + (x0−xB) λy (102) Substituting equation (101) into equation (102) gives

C01 =-((λy / λx) x0 + yp-
(Λy / λx) xp) λx

+ (X0−xB) λy

= − (Λy x0 + yp λx−λy xp)
+ (X0 -xB) λy

= −yp λx + λy xp−xB λy

= C1 That is, the value of equation (12) does not change.

Similarly, the value of equation (13) is

C02 = −y0λx + x0λy (103)

It can be seen that C02 = C2 and the value of equation (13) does not change.

On the other hand, in the involute gear, the contact point of the pair of meshing teeth is always on the action line, and the action line is a common normal line. Further, since the action line does not move even if the contact point of the pair of meshing teeth moves, the condition for keeping the values of C1 and C2 unchanged is satisfied. That is, even if the collision point changes from Pc to P0, the collision points Pc and P0
Are on the action line (common normal) of the involute gear, the values of C1 and C2 do not change, and the conditional expression (1)
Since no error occurs in 5), it is not necessary to adjust the moment of inertia.

FIG. 1 is a side view showing an embodiment of a camera mirror bounce prevention apparatus according to the present invention. In the figure,
The description of the same components as those in FIGS. 2 to 5 is omitted.

In FIG. 1, the shafts 5, 18 and 17 and the stopper 33 are fixed to a camera body (not shown).
The eccentric pin 21 is rotatably attached to a camera body (not shown). The mirror holding frame 2 is integrated with the support member 3. The support member 3 is rotatable around the shaft 5 and is urged counterclockwise by the force of the spring 30.

The support member 3 is formed with a tooth surface 3a of an involute gear that rotates about a shaft 5. One end of the spring 30 is attached to the support member 3, and the other end is attached to a camera body (not shown). The 45 ° receiving member 22 is rotatable around the shaft 18 and is urged counterclockwise by the force of the spring 26.

The 45 ° receiving member 22 is formed with a tooth surface 22a of an involute gear that rotates about the shaft 18. The tooth surface 22a meshes with the tooth surface 3a formed on the support member 3. The point Pi is between the tooth surface 3a and the tooth surface 22a.
Represents the point of contact with Further, a straight line RR passing through this point Pi
Is an action line (common normal) between the tooth surface 3a and the tooth surface 22a. Here, the tooth surface 22a and the tooth surface 3a are respectively
And the tooth surfaces of a pair of involute gears that can mesh and rotate with the shaft 5 as a rotation axis. The inertial lever 23 is rotatable about the axis 18 and is integrated with the 45 ° receiving member 22 by a pin 24. Weight 2
7 is attached to the inertial lever 23. The brake lever 28 is rotatable about the shaft 17 and
It is urged clockwise under the force of 6.

One end of the spring 26 is attached to the arm 22 b of the 45 ° receiving member 22, and the other end is attached to a pin 29 fixed to a brake lever 28. Spring 26
Has a stronger urging force than the spring 30. The arm 22 b of the 45 ° receiving member 22 is pressed against the eccentric pin 21 by the urging force of the spring 26. Also, the brake lever 28
Of the inertial lever 23 is pressed against the friction surface 23a of the inertial lever 23 by the urging force of the spring 26.

Next, the operation of the present invention will be described.

When the release button of the camera body is pressed, the support member 3 rotates clockwise against the spring 30 by a known method. Then, when it collides with the stopper 33, it stops. The state of the support member 3 at this time is shown by a broken line in FIG.

Next, a shutter (not shown) is operated to expose the film. Thereafter, the support member 3 rotates counterclockwise by the action of the spring 30. Eventually, the tooth surface 3a collides with the tooth surface 22a at the point Pi. Weight 27 here
Is appropriately set, the support member 3 stops with almost no bouncing, as described in the equation (15), so that bouncing can be prevented.

According to the embodiment described above, the shape of the collision point between the mirror member and the 45 ° receiving member is formed as an involute curve. Therefore, even if the position of the mirror holding frame 2 is adjusted by the eccentric pin 21, the common method is used. Since the line RR does not change, the conditional expression (15) for preventing bouncing does not change. For this reason,
Even if the position of the mirror holding frame 2 is adjusted, an error does not occur in the condition for preventing the bounce, and an inertia moment adjusting device and an adjusting operation for correcting the error can be omitted. Therefore, assembling adjustment of the camera becomes easy, and the number of parts and the cost can be reduced.

In the embodiment, the tooth surface 3a and the tooth surface 22a are described as the tooth surfaces of the involute gear. However, the present invention is not limited to this, and the contact point Pi may move on a line approximating the common normal line RR. The tooth surface of a possible gear, for example, a polygonal or arcuate gear may be used.

[0066]

As described above, according to the present invention, the shape of the colliding portion between the mirror member and the mirror receiving member is an involute curve or an approximate curve thereof. Therefore, even if the position of the mirror member is adjusted, the collision occurs. Since the common normal of the portion hardly changes, the condition for preventing bouncing hardly changes. Therefore, even if the position of the mirror member is adjusted, the error that occurs in the condition for preventing bounce is very small, and the moment of inertia adjustment device and adjustment work for error correction can be omitted.
The number of parts can be reduced and the camera can be easily adjusted, whereby the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of a camera mirror bounce prevention device according to the present invention.

FIG. 2 is a conceptual diagram illustrating the principle of a conventional camera mirror bounce prevention device according to the present invention.

FIG. 3 is a perspective view showing a first embodiment of a bounce prevention device for a camera mirror according to the present invention;

FIG. 4 is a side view showing a first embodiment of a bounce prevention device for a camera mirror according to the present invention.

FIG. 5 is a characteristic diagram showing a first embodiment of a camera mirror bounce prevention device according to the present invention.

[Explanation of symbols]

 2 Mirror holding frame 3 Support member 3a Tooth surface 13 Stopper 17 Shaft 18 Axle 21 Eccentric pin 22 Member 22a Tooth surface 22b Arm 23 Inertial lever 23a Friction surface 24 Pin 28 Brake lever 28a Contact surface 29 Pin 33 Stopper

Claims (4)

(57) [Claims] A mirror member that can reciprocate between an observation position and a photographing position; and a mirror member that rotates when a collision occurs to absorb the angular momentum of the mirror member. A mirror receiving member for regulating the position to a predetermined rotation angle; and a braking member for braking the relative movement of the mirror receiving member with respect to the camera body, where the mirror member collides with the mirror receiving member. A bounce prevention device for a mirror for a camera, characterized in that each of the shapes has an involute curve. 2. A mirror member reciprocally rotatable between an observation position and a photographing position; and a mirror member which rotates when a collision occurs to absorb the angular momentum of the mirror member. A mirror receiving member for regulating the position to a predetermined rotation angle; and a braking member for braking the relative movement of the mirror receiving member with respect to the camera body, where the mirror member collides with the mirror receiving member. A bounce preventing device for a camera mirror, wherein each of the shapes is an approximate arc of an involute curve. 3. A mirror member reciprocally rotatable between an observation position and a photographing position; and a mirror member that rotates when a collision occurs to absorb the angular momentum of the mirror member, and that the mirror member is rotated. A mirror receiving member for regulating the position to a predetermined rotation angle; and a braking member for braking the relative movement of the mirror receiving member with respect to the camera body, where the mirror member collides with the mirror receiving member. A bounce prevention device for a camera mirror, wherein each of the shapes is a polygonal line approximating an involute curve. 4. The involute curve according to claim 1, wherein said involute curve is a tooth profile of a pair of involute gears meshing about a rotation center of said mirror member and a rotation center of said mirror receiving member. 4. The camera mirror bounce prevention device according to 3.