Photography – Having variable focal length of camera objective – Power zoom
Reexamination Certificate
2000-07-26
2004-09-07
Gray, David M. (Department: 2851)
Photography
Having variable focal length of camera objective
Power zoom
C396S131000, C396S137000, C348S240300
Reexamination Certificate
active
06788888
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical device such as a lens device or the like used in television image sensing, and an image sensing system using the optical device.
2. Related Background Art
As a lens device used in television image sensing or the like, a device shown in
FIGS. 3 and 4
is known. In this lens device, a movable lens group (not shown) held in a housing
39
can be moved by rotating an operating ring
31
provided to the outer circumferential surface of a device main body
30
manually or by a motor, or a stop (not shown) can be adjusted.
A drive unit
32
provided near the housing
39
houses a motor
35
for motor-driving the operating ring
31
, a control circuit (not shown), and the like, and a motor operating switch
33
, which is operated by the user to operate the motor
35
to drive the movable lens group is provided on the outer surface of the drive unit
32
.
This lens device has a clutch mechanism for connecting/disconnecting a driving power transmission path for transmitting the drive force of the motor
35
to the operating ring
31
, as shown in FIG.
4
.
More specifically, the clutch mechanism is made up of an idler gear
37
provided between an operating gear portion
34
formed on the operating gear
31
and an output gear
36
of the motor
35
, and a clutch operating lever (not shown) which slides the idler gear
37
in the axial direction (longitudinal direction) of an idler shaft
38
.
Upon motor driving, the clutch operating lever is operated to shift the idler gear
37
to mesh with both the operating gear portion
34
and output gear
36
, thus connecting the drive force transmission path. Upon manual driving, the clutch operating lever is switched to shift the idler gear
37
to disengage from the output gear
36
, thus disconnecting the drive force transmission path.
However, in the aforementioned lens device, the clutch operating lever must be operated to select the manual or motor driving mode of the operating ring. For this reason, operation is troublesome, and the manual and motor driving modes cannot be quickly switched, thus often failing to catch up with changes in image sensing situation.
Even when the drive force transmission path is connected, and while the movable lens group is motor-driven, the operating ring can be manually driven in terms of a structure. However, since a very large operating force is required due to the motor load, operation is not easy, and the motor is overloaded. Furthermore, when the movable lens group or the like is motor-driven via a camera control unit (CCU) placed at a position separated from this lens device and a camera to which that lens device is mounted, it is difficult for a person taking photographs who is near the camera to manually operate the operating ring preferentially.
It is, therefore, an object of the present invention to provide an optical device which is adopted quickly switch the motor-driven/manual state of a drive mechanism for driving a movable portion without requiring any special operation so as to avoid a problem such as overload of a motor when the movable portion is manually operated while the drive mechanism is set in the motor-driven state.
SUMMARY OF THE INVENTION
An aspect of the first invention of the present application that achieves the above object is characterized in that an optical device comprises:
an optical member that comprises the optical device;
an operating ring which can be rotated about an optical axis of the optical member and is used to drive the optical member;
a switching mechanism which transmits a drive force from a motor drive source to the operating ring, and can be switched between a state for motor-driving the optical member and a state for canceling motor driving of the optical member; and
control means for switching the switching mechanism between the state for motor-driving the optical member and the state for canceling motor driving of the optical member, and
the control means switches the switching mechanism to the state for canceling motor driving of the optical member on the basis of manual operation of the operating ring when the switching mechanism is set in the state for motor-driving the optical member.
In a preferred aspect, the control means detects manual operation of the operating ring on the basis of a load state of the motor drive source.
In a preferred aspect, the control means detects manual operation of the operating ring on the basis of a drive current value of the motor drive source.
In a preferred aspect, the control means detects manual operation of the operating ring on the basis of a counterelectromotive force produced in the motor drive source.
In a preferred aspect, the control means detects manual operation of the operating ring on the basis of a difference between a drive state of the optical member corresponding to a drive command, and an actually driven state of the optical member.
In a preferred aspect, the drive command is to command a drive position of the optical member, and the control means detects manual operation of the operating ring on the basis of a difference between the drive position command of the optical member, and an actually driven position.
In a preferred aspect, the drive command is to command a drive velocity of the optical member, and the control means detects manual operation of the operating ring on the basis of a difference between the drive velocity command of the optical member, and an actually driven velocity.
In a preferred aspect, the switching mechanism has a clutch mechanism for connecting/disconnecting drive force transmission between the operating ring and the motor drive source, and the control means switches the switching mechanism from the state for motor-driving the optical member to the state for canceling motor driving by switching the clutch mechanism from a connected state to a disconnected state.
In a preferred aspect, the optical member is a lens having a zoom function.
In a preferred aspect, the drive command of the optical member is input from operation means operated by a user.
In a preferred aspect, the drive command of the optical member is input from a control unit located at a position separated from the optical device.
In a preferred aspect, the drive command of the optical member is input from an image sensing device which is mounted on the optical device to be able to communicate therewith, and senses an image.
In a preferred aspect, the switching mechanism is driven by the motor drive source which operates in accordance with operation of motor operation means.
A second aspect of the invention of the present application that achieves the above object is characterized in that an image sensing system comprises:
an optical member that comprises an optical device;
an operating ring which can be rotated about an optical axis of the optical member and is used to drive the optical member;
a switching mechanism which transmits a drive force from a motor drive source to the operating ring, and can be switched between a state for motor-driving the optical member and a state for canceling motor driving of the optical member;
control means for switching the switching mechanism between the state for motor-driving the optical member and the state for canceling motor driving of the optical member; and
an image sensing device which is mounted on the optical device to be able to communicate therewith, and senses an image, and
the control means switches the switching mechanism to the state for canceling motor driving of the optical member on the basis of manual operation of the operating ring when the switching mechanism is set in the state for motor-driving the optical member.
In a preferred aspect, the control means detects manual operation of the operating ring on the basis of a load state of the motor drive source.
In a preferred aspect, the control means detects manual operation of the operating ring on the basis of a counterelectromotive force produced in the motor drive source.
In a preferred aspect, the con
Canon Kabushiki Kaisha
Gray David M.
Morgan & Finnegan , LLP
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