JP2518342Y2 - Camera shutter drive mechanism - Google Patents

Description

[Detailed description of the device] [Industrial applications]

The present invention relates to a drive mechanism for a shutter used in a still camera or an electronic still camera, and more specifically, it has a substantially 1
The present invention relates to an improvement of a drive mechanism that charges and releases a blade drive member that drives a shutter blade by cam connection with a rotating member that is operated by being connected to a motor that rotates in a direction.

[Prior art]

It is known that an elastic material such as a spring is used as a drive source of a shutter mechanism used in a still camera or an electronic still camera so that the energy stored in the elastic material is released to drive the shutter blades. ing. In this type of mechanism, a charge mechanism for returning the blade drive member, which is the driven member, to the set position while storing energy in the elastic material that is the drive source, and the blade drive member, which is the driven member, in the set position. A holding mechanism for holding, a mechanism for releasing this holding mechanism, etc. are required, and a mechanism having a cam mechanism using a motor as a driving source is known as a single member that combines these various mechanisms. There is. More specifically, the blade opening / closing lever itself or a member connected to the blade opening / closing lever is biased toward the forward limit by a spring, which is an example of an elastic material, and a cam is connected to a rotating member that rotates in one direction by a motor. Thereby pulling back the blade opening / closing lever or the like from the forward limit toward the set position against the biasing force of the spring, and stopping the rotary member at the set position to hold the blade opening / closing lever or the like at the set position. Further, by further rotating the rotating member from the set position, the hold of the blade opening / closing lever or the like is released, and the blade opening / closing lever or the like can travel from the set position toward the forward limit by the biasing force of the spring. And

[Problems to be solved and used by the device]

Although such a method is extremely excellent in that a single member also serves as various mechanisms, there is a problem that a normal set operation may not be performed due to load fluctuation. More specifically, when the rotating member stops at the set position, a current brake (a brake that supplies a reverse current sufficient to overcome the inertial force of the motor and the auxiliary mechanism) is generally used. However, the mechanical load may fluctuate due to the use environment of the camera and changes over time, and there is no guarantee that it will always be constant. For example, when the operation of mechanical members becomes poor due to use at low temperature or deterioration over time, it is expected that the operating speed of rotating members and other mechanical members will be slower than that at the time of design at the time of braking by the current brake. In such a case, the inertial force of those members is naturally low. On the other hand, the load applied to the motor during operation of the current brake is essentially only the rotating member, and the members around the blades are not added as a load.
The braking force of the current brake itself does not decrease so much. Therefore, there is a risk that the braking force of the current brake becomes excessive and the set position cannot be maintained. Also, the adjustment of the braking force of the current brake at the time of shipment becomes extremely delicate, and there is a high risk of deviating from the set position due to a slight adjustment error, and a routine for recovering from this when the set position is deviated. There is also the problem of having to prepare.

[Means for solving problems]

The present invention has been made in view of these problems, and prevents the set position from being unable to be maintained even under conditions where the braking force for stopping the rotating member at the set position becomes excessive. It is an object of the present invention to provide a driving mechanism for a camera shutter described above. In summary, the driving mechanism of the camera shutter of the present invention includes: a blade driving member connected to the shutter blade and biased in a direction for exposing the shutter blade; a direction for moving the blade driving member to a set position. A set member that is capable of traveling in a direction that is biased in a direction opposite to the direction in which the blade driving member is moved to the set position; A rotating member having a cam connecting roller that passes through the locus; a first cam portion that receives from the cam connecting roller a force that causes the setting member to travel in a direction that moves the blade driving member to the setting position. The setting portion, which is continuous with the first cam portion and has an arc-shaped second cam portion having a radius of curvature substantially equal to the radius of curvature of the turning locus of the cam coupling roller. Formed in relation to the material; such that the setting member positions the vane drive member in the setting position when the cam connecting roller is in contact with the second cam portion; By stopping the rotating member in a state of being in contact with the second cam portion to stop the setting member at the setting position of the blade driving member, and by retracting the cam connecting roller from the second cam portion. It is premised on a drive mechanism for a still camera shutter that releases the setting member; and a member formed with the first and second cam portions enters the traveling path of the cam connecting roller. A reversing prevention lever having a locking arm for swingably supporting the reversing prevention lever from the second cam portion to the first cam. It is urged by a force smaller than the rotational force of the cam connecting roller toward the portion, and the swing limit of the reverse rotation prevention lever due to this urging force is set at the position where the locking arm enters the traveling path of the cam connecting roller. And the swing limit of the reverse rotation preventing lever due to the running of the cam connecting roller is not substantially regulated.

[Action]

That is, according to the driving mechanism of the camera shutter of the present invention, the cam connecting roller acts on the first cam edge with the rotation of the rotating member to move the setting member to the setting position of the blade driving member. Further, since the radius of curvature of the second cam edge is equal to the radius of curvature of the running locus of the cam connecting roller, the set member does not substantially move while the cam connecting roller is in contact with the second cam edge. ， Maintain the set position. Then, when the cam connecting roller separates from the second cam edge, the setting member is released from the cam connecting roller. Since the swing limit of the reverse rotation prevention lever due to the running of the cam connection roller is not substantially regulated, the cam connection roller moves from the first cam edge to the second cam edge while rotating the reverse rotation prevention lever. When the cam connecting roller reaches the second cam edge, a reverse current is supplied to the driving motor to apply the current brake, and even if the rotating member is reversely rotated at this time,
Since the locking arm of the reverse rotation preventing lever has entered the traveling path of the cam connecting roller and its swing limit is restricted, the reverse rotation of the cam connecting lever is suppressed and the setting member maintains the set position.

【Example】

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows the principle of a shutter drive mechanism according to one embodiment of the present invention, and the present invention is applied to a drive mechanism of a focal plane shutter. Reference numeral 1 denotes a leading blade driving lever for opening and closing a leading blade group (not shown), which is swingably supported by a shaft 2 on the main plate. The engaging pin 1a, which is planted on the rear surface of the leading edge of the leading blade driving lever 1, penetrates a slot 3a formed in an arc shape around the shaft 2 on the main plate and engages with a leading blade group (not shown). The leading blade drive lever 1 can swing with the range of the slot 3a being maximized. The leading blade drive lever 1 is urged toward the forward limit by the spring 4, and when the leading blade drive lever 1 travels from the set position to the forward limit, the leading blade group (not shown) moves from the position where the exposure aperture is closed. Drive toward the position where the exposure aperture is opened. Conversely, when the leading blade drive lever 1 travels from the forward limit to the set position against the biasing force of the spring 4, the leading blade group (not shown) travels from the position where the exposure aperture is opened to the position where it is closed. It will be. Next, 5 is a trailing blade drive lever for opening and closing a trailing blade group (not shown), which is swingably supported by a shaft 6 on the main plate. The engaging pin 5a, which is planted on the rear surface of the leading edge of the trailing blade driving lever 5, penetrates through a slot 3b formed in an arc shape around the shaft 6 on the main plate and engages with the trailing blade group (not shown). The trailing blade drive lever 5 can be swung while maximizing the range of the slot 3b. The trailing blade drive lever 5 is biased toward the forward limit by the spring 7, and when the trailing blade drive lever 5 travels from the set position to the forward limit, the trailing blade group (not shown) moves from the position where the exposure aperture is opened. Drive toward the position that closes the exposure aperture. On the contrary, when the trailing blade drive lever 5 travels from the forward limit to the set position against the biasing force of the spring 7, the trailing blade group (not shown) travels from the position where the exposure aperture is closed to the position where it is opened. It will be. Next, 8 is a set bar for setting the drive levers 1 and 5 of the leading blade and the trailing blade. The long holes 8a and 8b formed along the longitudinal direction of the set bar 8 are formed in the base plate. The guide pins 3c and 3d are inserted, and the set bar 8 can move up and down within the range of the elongated holes 8a and 8b. At the outer edge of the set bar 8, there are formed a leading blade set piece 8c for setting the leading blade drive lever 1 against the spring 4 and a trailing blade set piece 8d for setting the trailing blade drive lever 5 against the spring 7. The leading blade set piece 8c and the trailing blade set piece 8d are engaged with the engagement pins 1a and 5a, respectively, in the process of lowering the set bar 8. Reference numeral 9 is an output pinion connected to the motor 10, and the shaft 11
Rotate around. A cam gear 12 meshes with the output pinion 9 and rotates about the shaft 13. still,
The teeth of each gear are omitted in the drawing. A coupling roller 12b is rotatably attached to a shaft 12a on the cam gear 12. A cam arm 8e extends to the outer edge portion of the set bar 8, and a first cam edge 8f and a second cam edge 8g that are cam-joined to the connecting roller 12b are formed on the upper surface of the cam arm 8e. The radius of curvature of the second cam edge 8g is equal to the radius of curvature of the swivel locus about the axis 13 of the cam edge contact point of the connecting roller 12b, so that the connecting roller 12b moves within the range of the second cam edge 8g. The set bar 8 maintains the set position during the operation. Next, 14 is a magnet for magnetically attaching the iron piece 1b formed on the leading blade drive lever 1, and the iron core 14a of the magnet 14 is supported by the spring 14b. Similarly, 15 is a magnet for magnetically attaching the iron piece 5b formed on the trailing blade drive lever 1, and the iron core 15a of the magnet 15 is supported by the spring 15b. Next, 16 is a reverse rotation preventing lever which is a feature of this embodiment, and the reverse rotation preventing lever 16 is pivotally attached to a shaft 17 on a cam arm 8e so as to be swingable. The reverse rotation prevention lever 16 has a source arm 16a at one end and a locking arm 16b at the other end.
The right-handed force is given by the spring 18 pulled during 8h, but the right-handed force is suppressed at the position where the curved portion 16c formed on the source arm 16a contacts the lower edge of the cam arm 8e. . On the other hand, in the initial state shown in FIG. 1, the tip end of the locking arm 16b penetrates into the turning path of the connecting roller 12b, but by rotating counterclockwise against the tension of the spring 18, the connecting roller 12b runs. It is designed to evacuate outside the route. Next, the operation of this embodiment will be described with reference to the above matters and FIGS. 2 to 4. 2 to 4 are partial views showing the peripheral mechanism of the reverse rotation preventing lever, of which FIG. 2 is a connecting roller.
FIG. 3 shows the state when 12b contacts the upper edge of the cam arm 8e, the moment when the connecting roller 12b passes over the position of the locking arm 16b of the reverse rotation preventing lever 16, and FIG.
Each shows the state where b has reached bottom dead center. When the motor 10 is energized from the state shown in FIG. 1, the motor pinion 9 rotates counterclockwise about the shaft 11 and the cam gear 12 rotates clockwise. As the cam gear 12 rotates, as shown in FIG.
The connecting roller 12b pushes down the set bar 8 from the time when 12b contacts the first cam edge 8f of the cam arm 8e, and in the process, the leading blade setting piece 8c and the trailing blade setting piece 8d engage the setting pins 1a and 5a, respectively. Meanwhile, the leading blade driving lever 1 and the trailing blade driving lever 5 are rotated counterclockwise. In this process, the connecting roller 12b contacts the locking arm 16b of the reverse rotation preventing lever 16, but since the biasing force of the spring 18 is smaller than the rotational force of the cam gear 12, the cam gear 12 reverses against the spring 18. Further rotate while turning the prevention lever 16 counterclockwise. When the connecting roller 12b is in contact with the second cam edge 8g as shown in FIG. 3 in the clockwise rotation of the cam gear 12, the set bar 8 is pushed down to the lower limit, and the set pins 1a and 5a.
Also turn left to the set position regulated by the slots 3a and 3b. At this time, the iron pieces 1b and 5b slightly push down the iron cores 14a and 15a against the support springs 14b and 15b, respectively. At this time, the connecting roller 12b goes over the tip of the locking arm 16b of the reverse rotation preventing lever 16, the reverse rotation preventing lever 16 is rotated right by the spring 18, and the curved portion 16c is engaged with the lower edge of the cam arm 8e. It The state at this time is the state shown in FIG. On the other hand, when the set bar 8 moves to the lower limit, the motor
A reverse current is supplied to 10, the cam brake 12 is stopped by the current brake in the state shown in FIG. 4, and the leading blade driving lever 1 and the trailing blade driving lever 5 are held at the set positions. By the way, since the braking force of the current brake and the inertial force of the members are balanced when the camera is shipped, the cam gear 12 is stopped in the vicinity of FIG. 4 by the supply of the reverse current. However, for example, when the operation of the cam gear 12, the set bar 8, and the blade peripheral mechanism deteriorates due to use at low temperature or deterioration over time, the traveling speed of these mechanical members becomes slower than that at the time of design, and when the reverse current is supplied. The inertial force of the mechanical member also decreases. Of course, under such conditions, the load applied to the motor during reverse current also increases, but the motor load during reverse current supply is essentially only the member on the motor side of the cam gear 12, and the blade peripheral mechanism does not. Therefore, it is expected that the braking force will not be attenuated due to low temperature or aging, and therefore the braking force will be relatively excessive, causing the cam gear 12 to largely reverse. However, in the case of the present embodiment, as shown in FIG. 4, after the connecting roller 12b has passed over the locking arm 16b and reached the second cam edge 8g, the reverse rotation prevention lever 16 is rotated right by the spring 18. Since the locking arm 16b has entered the traveling path of the connecting roller 12b, the connecting roller 12b is locked by the locking arm 16b even if the provisional link roller 12b is slightly reversed. Reverse rotation is suppressed with and the set position can be maintained. Then, when the photographer presses a shutter button (not shown), the magnets 14 and 15 are energized, and the leading blade driving lever 1 and the trailing blade driving lever 5 are magnetically attached at the set positions. Thereafter, the motor 11 is energized, the rotation of the motor 11 is transmitted, and the cam gear 12 further rotates clockwise from the position shown in FIG. Then, the connecting roller 12b is connected to the second cam edge 8g.
When retracted from, the set bar 8 returns to the upper limit due to the tension of the spring 8i, but the leading blade driving lever 1 and the trailing blade driving lever 5 are magnetically attached to the magnets 14 and 15 to maintain the set position. After that, when the magnets 14 and 15 are sequentially demagnetized with a time difference corresponding to the exposure second, the leading blade drive lever 1 and the trailing blade drive lever 5 travel sequentially to the forward limit by the springs 4 and 7, and the leading blades not shown in the figure. Performs a single exposure operation by traveling in the direction of opening the exposure aperture and in the direction of closing the exposure aperture by the rear blade (not shown). In the above description, the example in which the present invention is applied to the drive mechanism of the focal plane shutter has been shown, but it goes without saying that the present invention can be applied to a lens shutter other than the focal plane shutter. Further, in the above, the example in which the first cam edge 8f and the second cam edge 8g are formed on the cam arm 8e extended from the set bar 8 is shown, but a cam member having a cam edge is set. The set bar may be formed separately in association with the bar, and the set bar may be moved in association with the movement of the cam member.

【effect】

As described above, according to the present invention, even when the inertial force of the mechanical member is relatively reduced as compared with the braking force of the current brake due to use at low temperature or deterioration of the mechanical member over time, It is possible to avoid the risk of deviating from the set position due to the reverse operation caused by the brake. Therefore, according to the present invention, even if the inertial force or the braking force of the rotating member fluctuates due to the influence of aging or fluctuation of the power supply voltage, malfunction due to overrun or excessive braking is less likely to occur, and the shutter reliability is improved. The property is improved. Also, when adjusting the braking force of the current brake at the time of shipment, if the braking force is adjusted to be slightly excessive, it is possible to prevent both overrun and reverse rotation, and to recover the deviation of the set position. There is no need to prepare a routine.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention, FIG. 2 is a partial view of a state immediately after a connecting roller starts contact with a cam arm, and FIG. 3 is a connecting roller showing a locking arm of a reverse rotation preventing lever. Fig. 4 is a partial view at the moment of getting over, and Fig. 4 is a partial view when the connecting roller is near the bottom dead center. 1 ... Leading blade drive lever, 5 ... Rear blade drive lever 8 ... Set bar, 8f ... First cam edge 8g ... Second cam edge, 12 ... Cam gear 12b ... Connecting roller, 16 ... … Reverse rotation prevention lever 16a… Source arm, 16b… Locking arm 16c… Bending part

Claims (1)

(57) [Scope of utility model registration request] 1. A blade drive member connected to a shutter blade and biased in a direction for exposing the shutter blade, and a blade drive member that can travel in a direction for moving the blade drive member to a set position. Rotation having a set member biased in the direction opposite to the direction of moving to the set position and a cam connecting roller that rotates by transmitting rotation of a motor that rotates in substantially one direction and that passes through a circular locus And a first cam portion that receives a force from the cam connecting roller for moving the setting member in a direction to move the blade driving member to the setting position, and a first cam portion that is continuous with the first cam portion. An arc-shaped second cam portion having a radius of curvature substantially equal to the radius of curvature of the turning locus of the cam connecting roller in association with the setting member, The setting member to position the blade driving member in the setting position when the cam connecting roller is in contact with the second cam portion, and the rotation is performed while the cam connecting roller is in contact with the second cam portion. A still camera in which the setting member is stopped at the setting position of the blade driving member by stopping the member, and the setting member is released by retracting the cam connecting roller from the second cam portion. In a drive mechanism of a shutter for a vehicle, a reverse rotation preventing lever having a locking arm that penetrates into a traveling path of the cam connecting roller is swingably supported on a member on which the first and second cam portions are formed, The reverse rotation preventing lever is smaller than the rotational force of the cam connecting roller so that the locking arm moves from the second cam portion toward the first cam portion. The locking arm regulates the swing limit of the reverse rotation prevention lever due to the biasing force at the position where the locking arm has entered the traveling path of the cam connecting roller, and the reverse rotation accompanying the traveling of the cam connecting roller. A drive mechanism for a camera shutter, wherein the swing limit of the prevention lever is not substantially regulated.