JP3448381B2 - Camera positioning 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 camera positioning device for positioning a position member such as a lens driving mechanism or an aperture driving mechanism using a step motor as a driving source in a compact camera or the like. A drive member that travels in correspondence with the rotation direction of the motor; and a position member that travels following the drive member when the drive member travels in one direction. The present invention relates to a positioning device for a camera, which improves the positioning accuracy on the premise of a mechanism in which a position member is locked by a locking mechanism.

[0002]

2. Description of the Related Art In recent years, a step motor has been widely adopted as a drive source for a mechanism member for a camera, and a single step motor is also used as a drive source for a plurality of mechanisms in order to save mounting space and the number of parts. Is widely practiced.
For example, it is a preferable example to use the same stepper motor as the drive source for the shutter drive mechanism after positioning the lens drive mechanism, the aperture drive mechanism, etc. using the stepper motor as the drive source. When a single stepper motor is used as a drive source for multiple mechanisms, the lens drive mechanism, diaphragm drive mechanism, etc. are generally driven to a desired position and locked by a ratchet or other locking mechanism. After that, a time-division drive system such as actuating a shutter is adopted.

Therefore, FIG. 4 shows an example of such a conventional mechanism. In the drawing, reference numeral 1 denotes a shutter base plate, and an aperture 1a for exposure is punched in a central portion of the shutter base plate 1. A drive ring 2 and a lens drive ring 3 are sequentially supported on the shutter base plate 1 so as to be rotatable around an aperture 1a, and the lens drive ring 3 is taken outside the drawing when left-handed from the initial state shown in FIG. It is associated with a taking lens (not shown) so as to extend the taking lens. Further, 4 is a step motor having a step rotation angle of, for example, 45 degrees, and 4a is an output pinion of the step motor 4. The rotation of the output pinion 4a is transmitted to the two-stage gear 5 including the large diameter wheel 5a and the small diameter wheel 5b. Further, a rack 2a that meshes with the small diameter wheel 5b is formed on a part of the outer periphery of the drive member member 2, and the rotation of the output pinion 4a is increased by the two-stage gear 5 and transmitted to the rack 2a, and the drive ring 2 rotates in the same direction as the motor pinion 4a.

On the other hand, the lens drive ring 3 is biased by the spring 6 in the right-handed direction, but the lens drive ring 3 is initially in a state shown in FIG.
Right turn is restricted at the position shown in. An engaging protrusion 2b for engaging the lens drive ring 3 to transmit a left-handed force to the lens drive ring 3 is formed on the outer edge of the drive ring 2, and the lens drive ring 3 has the engagement protrusion 2b. An engagement point 3a is formed on the left-handed path of 2b. Therefore, when the drive ring 2 is rotated counterclockwise, the engagement protrusion 2b moves to the engagement point 3a.
Lens drive ring 3 from the time when
Following this, the lens is rotated counterclockwise, and the photographing lens (not shown) is extended in correspondence with the amount of counterclockwise rotation of the lens drive ring 3.

In this type of dual-purpose drive mechanism, after the drive ring 2 rotates the lens drive ring 3 counterclockwise to a desired position, the blade opening / closing lever 7 is rotated in the clockwise direction of the drive ring 2.
Is operated to open / close the shutter blades 8 (details of the configuration operation of the blade opening / closing lever 7 and the shutter blades 8 will be described later). As described above, the lens drive ring 3 is driven by the spring 6. Since it is given a rightward turning characteristic, it is necessary to lock the lens driving ring 3 by some mechanism when the driving ring 2 is turned rightward.

Locking of the lens driving ring 3 is generally performed by a locking mechanism using a ratchet or the like. More specifically, a rack 3b is formed on the lens drive ring 3, and the rack 3b is meshed with a pinion 9a that rotates together with the ratchet gear 9b. Reference numeral 10 denotes a ratchet lever which is pivotally supported by a shaft 10a and is given a right-handed force from a spring (not shown). The ratchet lever 9 has a pawl 19b at the tip thereof.
Lock either tooth of b.

[0007]

By the way, in the conventional type mechanism described above, the number of teeth of the pinion 9a constituting the locking mechanism and the number of teeth of the pinion 9a are two.
By matching the number of teeth of the small wheel 5b constituting the step gear 5 with each other, the rotational speed of the pinion 9a and the rotational speed of the two-step gear 5 are matched with each other. Therefore, in order to associate the step rotation angle of the step motor 4 with the teeth of the ratchet gear 9a in a one-to-one correspondence, the number of teeth of the ratchet gear 9a must match the number of teeth of the large wheel 5a. The accompanying drawings show the actual shutter mechanism in a scale-up of about 5 times, and the diameter of the ratchet gear 9b is about several millimeters as an actual product. Therefore, when the number of teeth of the ratchet gear 9a is made to coincide with the number of teeth of the large-diameter wheel 5a for double speed, the pitch of the ratchet gear 9a naturally becomes 1 mm or less, and waviness due to a slight component error or eccentricity may occur. There was a problem that there is a high risk that the locking position will shift due to wear.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a positioning device for a camera having excellent locking position accuracy. In summary, the camera positioning device of the present invention is capable of traveling in both forward and reverse directions by a step motor capable of rotating in the forward and reverse directions, a motor pinion fixed to the rotation shaft of the step motor, and a gear connected to the motor pinion. Drive member, a position member that is driven in the forward direction by the drive member while traveling in the forward direction, and is urged in the reverse direction, and has the same number of teeth as the motor pinion. A ratchet gear that is integrally formed with a pinion gear and that rotates by being gear-connected to the position member, and a member that locks the ratchet gear when the drive member shifts from traveling in the forward direction to traveling in the reverse direction. Stop member, the motor pinion, and the drive unit
Intervening between the material and mesh with the motor pinion
A large wheel and a small wheel that rotates integrally with the large wheel.
First two-stage gear, the position member, and the pinion gear
And has the same shape as the first two-stage gear.
The small-diameter wheel and the large-diameter wheel of the
A second two-stage gear meshing with the gear,
Drive member shifts from traveling in the forward direction to traveling in the reverse direction
When engaging the ratchet gear by the locking member
By locking it, the position member can be positioned.
In the positioning device for the camera,
Step rotation angle and the ratchet gear step times
Achieving the above objective by matching the turning angle
Is. Furthermore, the number of teeth of the ratchet gear and the motor
The object is achieved by matching the number of teeth of the tapinion .

[0009]

That is, according to the present invention, the number of teeth of the ratchet gear can be made equal to the number of teeth of the motor pinion.
For example, if one step angle is a 45 degree step motor,
The gear pitch of the ratchet gear can be set to 45 degrees, and the gear pitch of the ratchet gear can be made large, so that reliable locking can be performed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a mechanism diagram showing an example of a shutter drive mechanism that also serves as a lens drive mechanism according to an embodiment of the present invention, and the present invention is applied to the positioning of the lens drive mechanism. In the illustrated embodiment, elements common to those of the conventional example described with reference to FIG. 4 are denoted by the same reference numerals as those in FIG. 4, and duplicate description is omitted. The positional relationship between the drive ring 2 and the lens drive ring 3 is basically the same in the embodiment shown in FIG. 1, but in the embodiment shown in FIG. 3c is attached to an eccentric shaft, and the adjustment ring 3c is eccentrically rotated by using a sliver, whereby the relative position when the lens drive ring 3 is driven by the drive ring 2 can be adjusted. There is.

In FIG. 1, 11 is a motor pinion 4a.
Two-stage gear 5 for transmitting the rotation of the
Large-diameter wheel 11a and small-diameter wheel 11 having the same shape as the two-stage gear
It is a two-step gear (second two-step gear) having b, and its small diameter wheel 11b meshes with a rack 3b formed on the lens drive ring 3 (position member) . Further, 12a is a ratchet gear, and a pinion 12b that rotates integrally with the ratchet gear 12a constitutes a large-diameter wheel 1 that constitutes a two-stage gear 11.
It meshes with 1a. The number of teeth of the pinion 12b is the same as the number of teeth of the motor pinion 4a. Therefore, the rotation of the motor pinion 4a is transmitted to the lens drive ring 3a.
When turning left, the pinion 12b turns into the motor pinion 4a.
Will rotate in the same direction with the same step rotation angle. Therefore, when the step rotation angle of the step motor 4 and the teeth of the ratchet gear 12a are made to correspond one-to-one, the number of teeth of the ratchet gear 12a is set to the motor pinion 4a.
The number of teeth can be made to match, and the locking point accuracy can be stabilized.

Reference numeral 13 denotes a ratchet lever for locking the ratchet gear 12a, which is a shaft 13a on the main plate 1.
While being swingably supported by the lever, a rightward turning force is applied from a spring (not shown), and a claw 13b at the tip thereof locks one of the teeth of the ratchet gear 12a. It should be noted that in the drawings, each spring shows only the urging direction simply by an arrow, except for a particularly important one.

Next, the operation of this embodiment will be described with reference to the above matters. First, when the normal rotation pulse is supplied to the step motor 4 to rotate the motor pinion 4a counterclockwise with the state shown in FIG. 1 as the initial state, the rotation of the motor pinion 4a is increased by the two-stage gear 5 and transmitted to the rack 2a, The drive ring 2 rotates in the same direction as the output pinion 4a. The V formed on the drive ring 2 during the counterclockwise rotation of the drive ring 2.
The character-shaped cam 2c passes through the position of the cam follower 7a of the blade opening / closing lever 7, but since the lens drive ring 3 is in the initial position at this point, the cam follower 7a contacts the lens driving ring 3 and the blade open / close lever 7 rotates to the right. Are regulated, so that the shutter blade 8 does not operate.

On the other hand, the lens drive ring 3 is biased by the spring 6 in the clockwise direction, but the lens drive ring 3 is initially set by a stopper (not shown) in FIG.
Right turn is restricted at the position shown in. Then, in the process in which the drive ring 2 rotates counterclockwise, the lens drive ring 3 follows the drive ring 2 and rotates counterclockwise from the time when the engaging projection 2b formed on the outer edge of the drive ring 2 engages the adjustment ring 3c. The photographing lens (not shown) is extended corresponding to the left-handed rotation amount of the lens drive ring 3. Since the adjusting ring 3c is eccentrically supported with respect to the lens driving ring 3, the adjusting ring 3c
The relative position of the lens drive ring 3 with respect to the drive ring 2 can be adjusted by rotating c with a slip.

Since the rack 3b formed on the lens driving ring 3 meshes with the small diameter wheel 11b constituting the two-stage gear 11, the lens driving ring 3 rotates counterclockwise as described above. The two-stage gear 11 rotates clockwise, and the large wheel 11a rotates the ratchet gear 12a counterclockwise through the pinion 12b. Then, in the process in which the ratchet gear 12a is left-handed in this way, the ratchet lever 13 which is given a right-handed habit by a spring (not shown), the claw 13b at the tip goes over the claw of the ratchet gear 12a one by one.

When the lens drive ring 3 is rotated counterclockwise to the target position in this manner, a reverse rotation pulse is supplied to the step motor 4 and the motor pinion 4a is rotated clockwise. The rotation of the motor pinion 4a is transmitted to the drive ring 2 via the two-step gear 5, and the drive ring rotates right. Therefore,
The engaging protrusion 2b formed on the drive ring 2 is an adjustment ring 3
The lens drive ring 3 is moved in a direction away from c, and the lens drive ring 3 is slightly rotated right by the biasing force of the spring 6. Therefore, the rack 3b formed on the lens drive ring 3 has the two-stage gear 1
The ratchet gear 12a is slightly rotated rightward through the 1 and the pinion 12b. Incidentally, FIG. 2 shows a state immediately after the step motor 4 starts reversing after the lens driving ring 3 is driven to the Nth stage in this way.

In this way, the ratchet gear 12a rotates slightly to the left, but since the ratchet lever 13 is given a right-handed force by a spring (not shown), when the teeth of the ratchet gear 12a are engaged with the pawls 13b. Thus, the right rotation of the ratchet gear 12a is stopped, and the right rotation of the lens drive ring 3 is also stopped. Therefore, thereafter, every time the motor pinion 4a turns right by one step, only the drive ring 2 turns right.

When the V-shaped cam 3c formed on the drive ring 2 passes through the position of the cam follower 7a formed on the blade opening / closing lever 7 while the driving ring 2 is rotating rightward, the blade opening / closing lever 7 is rotated by a spring (not shown). The urging force causes the cam follower 7a to fall to the V-shaped cam 3c and rotate right about the shaft 7b. Therefore, while the pin 7c fixed to the back surface of the blade opening / closing lever 7 engages with the elongated hole 8b formed in the shutter blade 8, the shutter blade 8 is rotated counterclockwise about the axis 8a to expose the exposure aperture 1a. Open. Incidentally, FIG. 3 shows a state in which the shutter blade 8 is thus opened.

When the supply of the reverse rotation pulse to the step motor 4 is restarted at the timing corresponding to the desired exposure time, the rotation of the motor pinion 4a is transmitted and the drive ring 2 is further rotated rightward. The cam follower 7a of the blade opening / closing lever 7 rides on the V-shaped cam 3c, and the pin 7c rotates the shutter blade 3 clockwise to close the aperture 1a. Then, at a timing before the drive ring 2 is rotated rightward to the initial position, the projection 2d formed on the drive ring 2 causes the ratchet lever 13 to rotate leftward against the right-handed force from the spring (not shown). The gear 12a is released from the ratchet lever 13. Therefore, the lens drive ring 3 rotates the two-step gear and the ratchet gear 12a while rotating clockwise to the initial position by the urging force of the spring 6 to complete one photographing operation.
In the above description, the case where the photographing lens is positioned is shown as an example of the positioning device, but it goes without saying that the present invention can be applied to other positioning devices such as positioning of a diaphragm blade formed separately from the shutter blade. Yes.

[0020]

As described above, according to the present invention, since the step rotation angle of the step motor and the step rotation angle of the ratchet gear match, the gear pitch of the ratchet gear can be made large, and the product It is possible to prevent the accuracy of the locking point from deteriorating due to waviness and wear due to manufacturing error and eccentricity.

[Brief description of drawings]

FIG. 1 is a mechanism diagram showing an initial state of a shutter mechanism that also serves as a lens driving mechanism according to an embodiment of the present invention.

FIG. 2 is a mechanism diagram showing a state in which a lens driving ring is extended to an N-step position in the embodiment shown in FIG.

FIG. 3 is a mechanism diagram showing an opening state of shutter blades in the embodiment shown in FIG.

FIG. 4 is a mechanism diagram showing a conventional mechanism.

[Explanation of symbols]

2 Drive member 2a rack 2b Engagement protrusion 3 Lens drive member 3b rack 3c adjustment ring 4 step motor 4a Motor pinion 5 two-stage gear 5a large diameter vehicle 5b small wheel 6 spring 11 Two-step gear 11a Large diameter vehicle 11b small diameter vehicle 12a ratchet gear 12b pinion 13 Ratchet lever

Front page continued (58) Fields surveyed (Int.Cl. ⁷ , DB name) G02B 7/09 G03B 3/10 G03B 13/34

Claims (2)

(57) [Claims] 1. A forward / reverse rotatable step motor, a motor pinion fixed to a rotation shaft of the step motor, a drive member gear-connected to the motor pinion and capable of traveling in both forward and reverse directions, and the drive member. In the process of traveling in the forward direction, a position member driven in the forward direction by being driven by the drive member and biased in the reverse direction, and a pinion gear having the same number of teeth as the motor pinion are integrally formed, A ratchet gear that rotates by being gear-connected to the position member, a locking member that locks the ratchet gear when the drive member shifts from traveling in the forward direction to traveling in the reverse direction, and the motor pinion A first two-stage gear that is interposed between the drive member and a large-diameter wheel that meshes with the motor pinion and a small-diameter wheel that rotates integrally with the large-diameter wheel; A second two-stage gear, which is interposed between the pinion gears, comprises a small-diameter wheel and a large-diameter wheel having the same shape as the first two-step gear, and the large-diameter wheel meshes with the pinion gear. A camera configured to position the position member by locking the ratchet gear by the locking member when the drive member shifts from running in the forward direction to running in the reverse direction. A positioning device for a camera, wherein the step rotation angle of the step motor and the step rotation angle of the ratchet gear are matched. 2. The positioning device for a camera according to claim 1, wherein the ratchet gear has the same number of teeth as the motor pinion.