JPS60263910A - Lens driving device - Google Patents

Abstract

PURPOSE:To switch and use the same motor for both focusing and zooming and to reduce the weight and cost of the lens driving device by engaging the motor with a power varying means so that the rotation of the motor is transmitted only when a manual/automatic focusing means is set to a manual focusing side. CONSTITUTION:When a clutch changeover lever 37 is placed in an automatic focusing state, i.e. pressed as shown by an arrow 47, a clutch pulley 29 rotates together with a driving gear 24 in one body and a focus ring 23 is rotated by the motor 33 to move a focusing lens. When the clutch changeover lever 37 is in the opposite direction of the arrow 47 by operating an operation knob 37a to set the manual focusing state, the focus ring 23 is operated manually and when motor-driven zooming operation is performed in this state, a zoom switch 46, for example, is operated to drive the motor 33 through a control circuit 44, and a zoom ring 25 is rotated to perform the zooming operation.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a lens driving device that can be used in a zoom lens of a video camera or the like.

2. Description of the Related Art Structures of Conventional Examples and Their Problems In recent years, with the spread of video cameras, there has been a demand for zoom lenses with autofocus and electric zoom functions.

A conventional lens driving device will be described below with reference to the drawings. FIG. 1 is a diagram showing the main parts of a conventional lens driving device. A focus ring 2 for holding a table lens is provided at the front of a lens unit 1. has a spur gear 3.

Since the spur gear 3 is press-fitted into the focus motor 4 and meshes with the spur gear β, the focus ring 2 can be driven by the focus motor 4. Furthermore, a distance measurement sensor 6 configured with an infrared LED (light emitting diode), a light receiving element, etc. for measuring the distance to the subject is provided outside the lens unit 1, and is connected to the distance measurement circuit 7. ing. The motor drive circuit 8 compares the distance signal to the subject obtained by the distance measurement circuit 7 and the focus position signal of the focus ring 2, and drives the focus motor 4 in a direction that reduces the difference between these two signals. A predetermined voltage is supplied to rotate the motor. Further, the lens unit 1 has a zoom ring 9 in the middle part for driving a variable magnification lens, and meshes with a spur gear 10 provided on the outer circumference of the zoom ring 9 and a spur gear 12 press-fitted into a zoom motor 11. are doing. Therefore, zooming can be performed by moving the variable magnification lens in forward and reverse directions according to the polarity of the voltage supplied to the zoom motor 11.

However, in the above configuration, dedicated motors are required for focusing and zooming, so two motors must be used.

As a result, there are problems in that the weight increases and the cost becomes high, and the focus motor is not used when performing manual focus operation, so the motor usage efficiency decreases. .

OBJECTS OF THE INVENTION An object of the present invention is to provide a lens driving device that has autofocus and electric zoom functions, can use a motor efficiently, and is lightweight and inexpensive.

Structure of the Invention The lens driving device of the present invention includes a focusing means for focusing an optical image of a motor and an object, a switching means for switching the focusing operation of the focusing means between manual focusing and automatic focusing, and a focusing means for focusing an optical image of a motor and an object. The lens is configured to include a magnification changing means for changing the magnification of the optical image of the zooming means, and a mating means that engages to rotatably transmit the rotation of the motor to the magnification changing means only when the switching means is in manual focusing, This makes it possible to efficiently utilize the motors by switching between using the same motor, and it is possible to provide a lightweight and inexpensive lens driving device.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a block diagram of a main part of a lens driving device according to an embodiment of the present invention, showing a state during autofocus operation. The front part of the lens unit 21 has a focus ring 22 that holds and rotates a focusing lens to move in the optical axis direction, and a gear 23 provided on the outer periphery of the focus ring 22 is a focus ring drive gear 24. It meshes with.

Similarly, the rear part of the lens unit 21 has a zoom ring 26 for operating the variable magnification lens.
A gear 26 provided on the outer periphery of the zoom ring drive gear 27
It meshes with. The focus ring drive gear 24 and the zoom ring drive gear 27 are rotatably held by a shaft 28, and there is a space between the focus ring 1 drive gear 24 and the zoom ring drive gear 27 that is slidable relative to the shaft 28. , and has two clutch pulleys held rotatably. One side 2 of clutch pulley 29
9a can come into contact with a felt ring 30 bonded to the side surface of the focus ring drive gear 24, and the other side surface 29b of the clutch pulley 29 can come into contact with a felt ring 31 bonded to the side surface of the zoom ring drive gear 27. This is possible, and a gear 32 is provided on the outer periphery of the side surface 29b. The gear 32 meshes with a gear 35 that is press-fitted onto a rotating shaft 34 of a motor 33 that has a built-in speed reduction mechanism.

Furthermore, the clutch pulley 29 has a concave portion 29C in the middle thereof which engages with a roller 36, and the roller 36 is rotatably held with respect to a shaft 38 implanted at one end of a clutch switching lever 37. . The clutch switching lever 37 is rotatably provided on a support shaft 39, and biased to one side by a torsion spring 40. Further, the other end of the clutch switching lever 37 has an operating knob ε37a.

Externally, the lens unit 21 has a distance measuring sensor 41 composed of an infrared LED (light emitting diode) and a light receiving element for measuring the distance to the subject, and is connected to a distance measuring circuit 42. .

The focus ring 22 still has a built-in encoder (not shown) for detecting the focusing distance of the focusing lens, and the out-of-focus detection circuit 43 detects the signal from the encoder and the distance measurement circuit 42. Compare the signals and distance measuring circuit 42
If there is a predetermined difference between the measured distance to the subject by the camera and the current focusing distance of the focusing lens, the motor 33 is controlled via the control circuit 44 in a direction that reduces the difference in distance between the two. It is configured to rotate.

A switch 45 is provided near the clutch switching lever 37, and a switch 46 changes the operating state of the clutch switching lever 37, that is, when the clutch switching lever 37 is in the state shown in FIG. 2, it is in the autofocus state, and when it is in the state shown in FIG. In the state, it is detected that the camera is in manual focus state. The switch 45 is connected to the control circuit 44,
The control circuit 44 switches the zoom switch 46 only when the switch 45 detects that it is in the manual focus state.
It has a function of controlling the motor 33 to operate according to the operation of the zoom switch 46, and changing the direction of rotation of the motor 33 according to the operation direction of the zoom switch 46, thereby changing the direction of zooming.

The operation of the lens driving device of this embodiment configured as described above will be described below. First, driving of the focus ring 22 when the clutch switching lever 37 is in the state shown in FIG. 2, that is, in the autofocus state will be described. When the distance that the focusing lens is currently focused on is infinite,
When photographing a nearby subject (for example, the distance to the subject is 3 m), the distance sensor 41 measures this distance, and the focus distance of the focusing lens is determined by a signal from an encoder (not shown) built into the focus ring 22. The out-of-focus detection circuit 43 detects that this is different, and the control circuit 44 causes the motor 33 to rotate. At this time, since the clutch switching lever 37 is biased by the torsion spring 4°,
The roller 36 provided at the tip of the clutch switching lever 37 presses the recess 29c of the clutch pulley 29 in the direction of the arrow 47, and the side surface 29a of the clutch pulley 29 presses the felt ring 3o on the side surface of the focus link drive gear 24. . Therefore, the clutch pulley 29 can rotate integrally with the drive gear 24, and when the gear 35 of the motor 33 rotates in a predetermined direction, the gear 32 provided on the clutch pulley 29 rotates, causing the focus ring drive gear 24 to rotate. The focus ring 23 is rotated through the focus ring 23. The focusing distance of the focusing lens changes as the focus ring 22 rotates, and when the focusing lens moves until it matches the distance to the subject measured by the distance measurement sensor 41, the control circuit 44 stops the rotation of the motor 33. Stop. Further, when the focusing lens focuses on a short distance and the object is far away, the same operation as described above is performed, and the motor 33 rotates in the opposite direction to the above case, thereby rotating the focus ring 23 in the opposite direction.

Next, when the operating knob 37a is operated to set the clutch switching lever 37 to the state shown in FIG. Since it is separated from the ring 3o, the rotation of the motor 33 is not transmitted to the focus ring 23, and the focus ring 23 can be operated manually. When performing an electric zoom in this state, for example, when the zoom switch 46 is operated to the T side (telephoto side), the motor 33 is rotated in a predetermined direction by the control circuit 44. Since the clutch switching lever 37 is biased by the torsion spring 4o, the roller 36 presses the recess 29c of the clutch pulley 29 in the direction of the arrow 48, and the side surface 29b of the clutch pulley 29 is pressed against the zoom ring,
The felt ring 31 on the side surface of the drive gear 27 is pressed. Therefore, the rotation of the motor 33 is controlled by the gear 35. The power is transmitted to the clutch pulley 29 by the gear 32, and the zoom ring drive gear 27 can rotate integrally with the clutch pulley 29, so the motor 33 can rotate the zoom ring 26 and perform zooming toward the telephoto side. .

On the other hand, when the zoom switch 46 is operated to the W side (wide-angle side), the motor 33 rotates in the opposite direction to that in the above case, so that zooming operation can be performed to the wide-angle side. When zooming, if you zoom at the edge 1 of the zoom range and operate the zoom switch 45, the felt ring 31 and the side surface 29 of the clutch pulley 29
By slipping between the positions b, a large load is prevented from being applied to the motor 33.

As described above, according to this embodiment, since the same motor can be switched and used, the utilization rate of the motor can be improved, and a lightweight and inexpensive lens driving device can be provided.

Effects of the Invention As is clear from the above description, the present invention includes a motor and a focusing means for focusing an optical image of a subject, and a switching switch for switching the focusing operation of the focusing means between manual focusing and automatic focusing. a zooming means for changing the magnification of an optical image of a subject; and an engaging means that engages to rotatably transmit the rotation of the motor to the magnification changing means only when the switching means is in manual focusing mode. This allows focusing and zooming to be performed using the same motor.

Therefore, the motor can be used efficiently, and a lightweight and inexpensive lens driving device can be provided. In addition, by using a switching means for switching between manual focusing and automatic focusing, the motor is engaged with the variable magnification means during manual focusing, and the focusing means is not directly engaged with the motor. It also has the effect that the load torque during manual focusing (manual focus operation) is small and manual focusing can be easily performed.゛

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the main parts of a conventional lens driving device, and FIG. 2 is a diagram showing the main parts of a lens driving device according to an embodiment of the present invention.
FIG. 3 is a diagram showing the configuration of main parts during manual focusing in the same embodiment. 22...Focus ring, 26...
Zoom ring, 29...Clutch pulley, 33
...Motor, 37...Clutch switching lever, 37a...Control knob, 44...Control circuit, 46...Zoom switch. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2

Claims (1)

[Claims] A motor, a focusing means for focusing an optical image of a subject, a switching means for switching a focusing operation of the focusing means between manual focusing and automatic focusing, and a means for changing the magnification of an optical image of a subject. A lens driving device comprising: a magnification changing means; and an engaging means that engages to enable rotational transmission of the rotation of the motor to the magnification changing means only when the switching means is in manual focusing mode.