JP2001174887A - Camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the number of gears from being increased and the diameter of a gear from getting large in the case of dividing the driving force of a motor from a reduction gear train to a speed-up gear. SOLUTION: This camera is equipped with a driving mechanism for transmitting the driving force from an output gear 2 integrally rotating with the output shaft of the motor 1. The driving mechanism is constituted by using a three-step- gear 3 obtained by integrally forming a 1st reduction gear part 3a decelerating the rotation of the output gear, a 2nd reduction gear part 3c decelerating the rotation transmitted to the 1st reduction gear part and transmitting it to a 1st driving system and a speed-up gear part 3b accelerating the rotation transmitted to the 1st reduction gear part and transmitting it to a 2nd driving system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera having a mechanism for transmitting a driving force from a motor to a plurality of driving systems, and more particularly, to a lens driving system and a pulse for detecting a lens driving position and the like. The present invention relates to a camera having a mechanism for transmitting a motor driving force to a signal forming drive system.

[0002]

2. Description of the Related Art A zoom lens barrel of a compact camera is composed of a zoom drive system for changing a focal length and a focus drive system for focusing. These two drive systems are driven by the driving force of one actuator. The following have been proposed.

For example, an inner lens in which a front lens unit is linearly driven through a helicoid of a cam cylinder which is rotationally driven by a driving force from a lens barrel driving motor, and a rear lens unit is cut inside the cam cylinder. In the case of a two-group zoom lens driven by a cam, first, a lens barrel driving motor is driven to select a plurality of predetermined focal lengths (hereinafter, referred to as zoom positions) in a stepwise manner to perform a zoom position switching operation. After that, the focusing operation is performed by driving the lens barrel driving motor.

[0004] A system in which the zoom position switching operation and the focusing operation are selected and driven stepwise by one actuator in this manner is generally called step zoom. Hereinafter, this method is referred to as step zoom.

On the other hand, a method has been proposed in which the zoom operation and the focusing operation are driven by separate actuators.

In the above-described step zoom,
In particular, during a zooming operation or a focusing operation, it is necessary to finely control the position of the lens (the position of the lens barrel). Therefore, conventionally, control using a pulse plate and a mechanical switch or two pulse plates has been performed. That is, the position of the lens is controlled by counting the number of fine pitch signals formed as the lens moves with reference to the coarse pitch signal formed for each zoom position.

FIG. 5 shows the configuration of a conventional zoom reduction system for step zoom. The output of the lens barrel drive motor 30 is transmitted from a worm gear 31 that rotates integrally with the output shaft of the lens barrel drive motor 30 to a two-stage gear 32 consisting of a helical gear and a spur gear.
The speed is reduced to the gear 34 and transmitted to the gear 35.

The gear 35 moves the switch piece 41 with the projection 35a, and turns ON / O between the gear 35 and the ground piece 42.
By performing FF, a coarse pulse signal is formed.
This signal is turned ON / OFF once for each zoom position.

The motor driving force transmitted to the gear 35 is transmitted from the gear 35 to the cam cylinder 37 via the gear 36, thereby driving the lens.

Further, the motor driving force transmitted to the gear 33 drives the pulse gear 39 formed integrally with the pulse plate through the gear 38 at an increased speed. Then, the rotation of the pulse plate is detected by the photo interrupter 40, and a fine pulse signal is formed.

As another method of generating a fine pulse signal, there is a method of directly attaching a pulse plate to an output shaft of a motor and detecting its rotation by a photo interrupter.

[0012]

However, in order to form a fine pulse signal with the configuration shown in FIG. 5, the rotation of the motor, which has been decelerated, must be transmitted to the pulse plate at an increased speed. For this reason, a gear for increasing the rotation of the decelerated motor and a space for disposing the gear are required.

Further, in the method of directly attaching the pulse plate to the output shaft of the motor, it is not necessary to increase the rotation of the motor, but since the pulse plate rotates integrally with the output shaft of the motor,
There is a possibility that the pinion gear attached to the output shaft of the motor becomes large or the degree of freedom in layout is limited. Further, a pulse plate can be attached to the motor output shaft on the side opposite to the pinion gear, but this has the disadvantage of increasing the cost of the motor and increasing the space for arrangement.

In view of the above, the present invention provides a camera having a drive mechanism suitable for forming a pulse signal having a necessary and sufficient resolution particularly for lens drive control without increasing the cost or increasing the arrangement space. The purpose is.

[0015]

In order to achieve the above object, according to the present invention, there is provided a camera provided with a drive mechanism for transmitting a driving force from an output gear that rotates integrally with an output shaft of a motor. A first reduction gear for reducing the rotation of the output gear, a second reduction gear for reducing the rotation transmitted to the first reduction gear and transmitting the rotation to the first drive system;
A speed increasing gear portion for increasing the speed of the rotation transmitted to the first reduction gear portion and transmitting the rotation to the second drive system has a three-stage gear integrally formed.

That is, when the driving force is divided into the speed increasing gear train from the middle of the speed reducing gear train for reducing the motor rotation, a three-speed gear provided integrally with the first speed reducing gear portion for reducing the motor rotation is provided. By using gears, it is possible to reduce the number of gears constituting the second drive system, which is a speed increasing system, and reduce the gear diameter. In addition, to three-stage gear,
By integrally forming the second reduction gear portion for further reducing the motor rotation transmitted to the first reduction gear portion, the number of gears constituting the first drive system, which is the reduction system, can be reduced. Becomes As a result, it is possible to reduce the number of components, downsize components, save space, and increase the degree of freedom in component layout.

When the output gear is a worm gear, the first reduction gear portion is constituted by a helical gear meshing with the worm gear, and the second reduction gear portion and the speed increasing gear portion are constituted by spur gears. The first gear connected to the speed-up gear while increasing the reduction ratio between the worm gear and the helical gear
The motor driving force can be divided into the driving system and the second driving system connected to the second reduction gear unit.

When the first drive system is a lens drive system for driving the photographing lens, and the second drive system is a pulse signal formation drive system for detecting the drive position or drive amount of the lens drive system. In this method, a single motor can drive the lens and form and drive a pulse signal for detecting the lens position and the like, and can precisely control the lens position by reducing the pitch of the pulse signal with a simple configuration. It becomes possible.

[0019]

FIG. 1 is a plan view of a main part of a step zoom type zoom lens driving mechanism provided in a camera according to an embodiment of the present invention, and FIG. 2 is a sectional view of FIG. FIG. 3 is a side view of the three-stage gear.

In these figures, reference numeral 1 denotes a DC motor for driving a zoom lens barrel, and its output shaft has a worm gear 2.
Is press-fitted and rotates integrally with the output shaft.

Reference numeral 3 denotes a three-stage gear, which is a helical gear (first gear).
A reduction gear portion) 3a; a large spur gear portion (speed increasing gear portion) 3b having a larger diameter (more teeth) than the helical gear portion 3a; and a smaller diameter (smaller number of teeth) than the helical gear portion 3a. And the small spur gear portion (second reduction gear portion) 3c are integrally formed so as to be arranged in the gear axis direction in this order.

The helical gear portion 3a is meshed with the worm gear 2, and reduces the rotation from the motor 1. Also,
The small spur gear portion 3c meshes with the gear 4, and further reduces the motor rotation transmitted to the helical gear portion 3a to reduce the gear rotation.
(First drive system: this zoom deceleration drive system will be described later).

On the other hand, the large spur gear portion 3b is provided with a pulse plate 16a.
Are engaged with a pulse gear 16 integrally formed, and increase the speed of the motor rotation transmitted to the helical gear portion 3a to transmit the rotation to the pulse gear speed increasing drive system (second drive system).

Here, the motor 1 is driven by the helical gear 3a.
In order to rotate the pulse plate 16a (pulse gear 16) after the third gear 3, a gear for increasing the speed of the pulse plate 16a is required separately from the zoom reduction drive system. In this embodiment, however, the reduction of the motor rotation by the helical gear 3a of the three-stage gear 3, the increase of the pulse gear 16 by the large spur gear 3b, and the reduction of the zoom reduction drive system by the small spur gear 3c are described. Since a single component is used, the number of components can be reduced, space can be saved, and the degree of freedom in component layout can be increased.

Reference numeral 17 denotes a photointerrupter which detects the rotation of the pulse plate 16a and generates a fine pulse signal (hereinafter, referred to as a first signal). In order to accurately control the position of the lens, it is preferable that the pitch of the pulse signal generated by the pulse plate 16a and the photo interrupter 17 be as small as possible within the range of the resolution of the photo interrupter.
In order to reduce the pitch of the pulse signal, it is necessary to reduce the pitch of the pulse plate or increase the rotation speed of the pulse plate. However, making the pitch of the pulse plate finer has limitations in manufacturing, and raises cost and assembly problems. Therefore, in the present embodiment, a method of increasing the rotation speed of the pulse plate is selected.

Next, the configuration of the zoom reduction drive system will be described. The gear 4 is meshed with the gear 5, and the gear 5 is inserted into the gear 7 together with an arc-shaped leaf spring 6. As a result, when the lens barrel is pressed with a strong external force, the gear 5 and the gear 7 idle through the leaf spring 6, thereby preventing an unreasonable load from being applied to the zoom deceleration drive system and a cam described later. A phase shift between the cylinder 10 and the gear 8 can be prevented.

The gear 7 meshes with the gear 8 and the gear 8
Presses the switch section 18 with the projection 8a when rotating, and turns ON / OFF with the ground section 19,
A coarse pulse signal (hereinafter, referred to as a second signal) is generated.

The motor driving force transmitted to the gear 8 is transmitted to the gear portion 10a of the cam cylinder 10 via the gear 9, whereby the cam cylinder 10 rotates. Reference numeral 11 denotes a first-group holder that holds the first-group lens 14, 12 denotes a second-group holder that holds the second-group lens 15, and 13 denotes a shutter base plate that fixes the first-group holder 14 and holds a shutter mechanism (not shown). It is.

As the cam cylinder 10 rotates, the shutter base plate 13 is driven in the front-rear direction by a helicoid cut in the cam cylinder 10. In addition, the second group holder 12 is also 3
The cam barrel 10 has a protrusion 12a formed in the
The cam cylinder 10 is driven in the front-rear direction by rotation of the cam cylinder 10. As a result, the first group lens 14 and the second group lens 15 can move in the front-rear direction with the rotation of the cam barrel 10.

FIG. 4 shows the amount of lens movement to four zoom positions W (wide), M1 (middle 1), M2 (middle 2), and TELE (tele) in the above-described step zoom type zoom lens driving mechanism. 4 schematically shows a relationship with a pulse signal.

The first lens unit 14 moves linearly with the rotation of the motor. One group lens 14 between each zoom position
Are the same.

On the other hand, the amount of movement of the second group lens 15 to each zoom position during zooming and the amount of movement differs for each zoom position during focusing at each zoom position. However, the focus area A indicating the motor rotation amount for focusing at each zoom position is the same for each position.

The first signal is supplied to the pulse plate 16 as described above.
The rotation of a is detected by the photo interrupter 17 and is formed as a fine pulse signal. The second signal is generated when the gear 8 rotates by using the switch section 1 at the projection 8a.
8 is formed by turning on / off the ground piece 19 by pressing the button 8.

The second signal is turned on / off once at each zoom position. In the present embodiment, the rising (or falling) of the second signal is detected at the time of zooming and focusing, and the number of pulses of the first signal is counted based on the detection time, and a predetermined pulse is determined. (Count) The motor 1 is driven for several minutes.

For example, when the focus operation is performed when the subject distance is 0.6 m (closest) at the wide position,
First, a target stop position of the lens corresponding to the subject distance is determined. This is because the distance measurement information from the distance measurement device is
And retrieves the target stop position corresponding to the distance measurement information from the memory. This target stop position is expressed as the number of pulses of the first signal based on the rising of the second signal. Then, energization of the motor 1 is controlled by the number of pulses.

In this case, the standby position of the lens before focusing needs to be set before the position of よ り (infinity) in the wide position. In the present embodiment, since the target stop position is 264 pulses when the subject distance is 0.6 m, the motor 1 is stopped when the first signal is transmitted 264 pulses based on the rising of the second signal.

In practice, however, the motor 1 is braked before the target stop position in consideration of the inertia of the motor and the like, and control is performed so that the motor stops exactly at the 264th pulse.

As described above, in the step zoom camera of the present embodiment, the pulse pitch of the first signal is reduced by increasing the rotation speed of the pulse plate 16a. Worm gear 2 as the output gear of the motor 1
The three-stage gear 3 including the helical gear 3a meshing with the worm gear 2 transmits the motor driving force separately to the zoom reduction drive system and the pulse gear increase drive system. For this reason, one motor 1 and a gear train with a small number of gears and a simple configuration can perform zooming and focusing driving of the lenses 14 and 15, and can make the pulse pitch of the first signal fine to accurately position the lens. Control can be performed.

In this embodiment, the case where the worm gear 2 is used as the output gear of the motor 1 and the helical gear portion 3a is provided in the third gear 3 has been described, but the output gear and the first reduction gear in the present invention are used. A gear other than these may be used as the unit.

In this embodiment, the case where the motor driving force is transmitted to the zoom reduction drive system and the pulse gear speed-up drive system has been described. However, the present invention is applied to other speed reduction drive systems and speed-up drive systems. The present invention can also be applied to a case where a motor driving force is transmitted.

Further, in this embodiment, the large spur gear portion 3b
Is disposed in the center, the helical gear portion 3a and the small spur gear portion 3b
Has been described using the three-stage gear 3 disposed on both sides of the large spur gear portion 3b, but the configuration of the three-stage gear in the present invention may be other than this.

[0042]

As described above, according to the present invention,
When the driving force is divided into a speed increasing gear train from the middle of the speed reducing gear train for reducing the motor rotation, a three-stage gear provided with a speed increasing gear unit integrally with the first reduction gear unit for reducing the motor rotation is used. Therefore, it is possible to reduce the number of gears constituting the second drive system that is the speed increasing system and reduce the gear diameter.
In addition, since the second reduction gear portion for further reducing the rotation of the motor transmitted to the first reduction gear portion is integrally formed with the three-stage gear, the gear constituting the first drive system, which is the reduction system, is formed. The number can be reduced. Therefore, it is possible to reduce the number of components, to reduce the size of components, to save space, and to increase the degree of freedom in component layout, and to reduce the size of the camera.

When the output gear is a worm gear, if the first reduction gear portion is constituted by a helical gear meshing with the worm gear, and the second reduction gear portion and the speed increasing gear portion are constituted by spur gears, the worm gear The motor driving force can be divided between the first drive system connected to the speed-increasing gear section and the second drive system connected to the second reduction gear section while increasing the reduction ratio between the helical gears.

If the first drive system is a lens drive system for driving the photographic lens, and the second drive system is a drive system for forming a pulse signal used for detecting the drive position or drive amount of the lens drive system. (1) A single motor can drive a lens and drive a pulse signal for detecting a lens position and the like, and can precisely control the lens position by reducing the pitch of the pulse signal with a simple configuration. Can be.

[Brief description of the drawings]

FIG. 1 is a plan view of a main part of a zoom lens driving mechanism of a camera according to an embodiment of the present invention.

FIG. 2 is a sectional view of FIG.

FIG. 3 is a side view of a three-stage gear used for the zoom lens driving mechanism.

FIG. 4 is a diagram schematically showing a relationship between a lens movement amount and a pulse signal in the camera.

FIG. 5 is a plan view of a main part of a zoom lens driving mechanism of a conventional camera.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Motor 2 Worm gear 3 3rd gear 10 Cam cylinder 16 Pulse gear 16a Pulse plate 17 Photo interrupter

Claims (6)

[Claims] 1. A camera comprising a driving mechanism for transmitting a driving force from an output gear that rotates integrally with an output shaft of a motor, wherein the driving mechanism reduces a rotation of the output gear; A second reduction gear section for reducing the rotation transmitted to the first reduction gear section and transmitting the reduced rotation to the first drive system; and increasing the rotation transmitted to the first reduction gear section to increase the second drive system. 3 integrally formed with a speed increasing gear portion for transmitting
A camera comprising a step gear. 2. In the three-stage gear, the second reduction gear portion has a smaller diameter than the first reduction gear portion, and the speed increasing gear portion has a larger diameter than the first reduction gear portion. The camera according to claim 1, characterized in that: 3. In the three-stage gear, the second reduction gear portion has fewer teeth than the first reduction gear portion, and the speed-up gear portion has more teeth than the first reduction gear portion. The camera according to claim 1 or 2, wherein: 4. The output gear is a worm gear, and in the three-stage gear, the first reduction gear portion is formed by a helical gear that meshes with the worm gear, and the second reduction gear portion and the speed increasing gear portion are The camera according to any one of claims 1 to 3, wherein the camera is configured by a spur gear. 5. In the three-stage gear, in the axial direction,
The camera according to any one of claims 1 to 4, wherein a first reduction gear section, a second reduction gear section, and a speed increasing gear section are formed. 6. The lens driving system according to claim 1, wherein the first driving system is a lens driving system for driving a photographic lens, and the second driving system is a pulse signal for detecting a driving position or a driving amount of the lens driving system. The camera according to any one of claims 1 to 5, wherein the camera is a forming drive system.