Photography – Exposure control system responsive to focal length
Reexamination Certificate
2000-07-26
2002-05-07
Perkey, W. B. (Department: 2851)
Photography
Exposure control system responsive to focal length
C396S065000, C396S078000, C396S072000, C396S505000, C348S347000, C348S352000, C348S362000, C359S697000, C359S739000
Reexamination Certificate
active
06385399
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical apparatus, such as a lens apparatus used for television shooting, and a shooting system including such an optical apparatus and an imaging apparatus.
2. Description of the Related Art
In a typical lens apparatus used for television shooting or the like, after a desired angle of view with respect to the subject has been set using a zoom optical element, a driving operation of the focus lens (focus lens unit) to perform a focussing operation, also varies the angle of view. Specifically, as the focus lens is driven so as to move the focus lens unit and shift the focus state toward the “infinity” side, the angle of view increases, and as the focus unit is driven so as to move the focus lens unit and shift the focus state toward the “close-up” side, the angle of view decreases.
In view of this, an angle-of-view correcting function recently has been proposed in which a zoom element is driven in an interlocked manner with the focus lens to restrain or compensate for variation in angle of view due to the focusing the operation of the focus lens.
In a lens apparatus provided with such an angle-of-view correcting function, the zoom element position and the focus lens position when the apparatus is at rest are read, the zoom element correction position needed for maintaining the current angle of view when the focus lens is driven to a new position is calculated, and the zoom element is driven so as to move to the calculated correction position.
The above-described angle-of-view correcting function is realized through accurate lens position control by an electric actuator, such as the zoom element motor. In view of this, in a lens apparatus provided with such an angle-of-view correcting function, it is a precondition that at least the zoom element should be driven electrically. Thus, a lens apparatus provided with such an angle-of-view correcting function has a construction that does not permit a zoom operation to be performed manually.
However, when the zoom element is driven for a purpose other than angle-of-view correction, for example, when an instantaneous angle of view correction is required, electric zooming cannot address this requirement. To comfortably obtain images under various shooting conditions, not only electric driving but also manual driving of the zoom element is required.
In view of this, it might be possible to provide the lens apparatus with a switch for switching between a state in which the zoom element can be electrically driven (hereinafter referred to as an “electric zooming mode”) and a state in which the zoom element can be driven manually (hereinafter referred to as a “manual zoom mode”), where operation of the switch operates a clutch or the like so as to connect or disconnect a driving force transmission path between the motor and the zoom element.
However, such a structure requires operation of the switch in order to use the angle-of-view correcting function each time it is determined that an angle of view correction in the manual zooming mode is required, resulting in poor operability, and making it impossible to quickly meet shooting requirements.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above problem in the prior art. Accordingly, it is an object of the present invention to provide an optical apparatus in which a movable portion, such as a zoom element, can be driven either electrically or manually, and in which it is possible to switch between an operation mode in which the movable portion is driven manually and an operation mode in which the movable portion is driven electrically, without the user having to perform any special mode switching operation.
In one aspect, the present invention relates to an optical apparatus comprising a first movable optical member, a second movable optical member, different from the first optical member, and operable in a first operation mode, in which the second optical member is movable by an electrical driving operation of the driving mechanism, and a second operation mode, in which the second optical member is movable by a manual driving operation, and control means for switching operation of the driving mechanism between the first operation mode and the second operation mode, wherein, when the driving mechanism is operable in the second operation mode, the control means switches operation of the driving mechanism to the first operation mode in response to a driving operation to the first optical member.
In one embodiment, the control means switches operation of the driving mechanism to the first operation mode in response to a command signal for a driving operation of the first optical member.
In another embodiment, the apparatus further comprises means for manually inputting a command signal for an electrical driving operation of the first optical member.
In another embodiment, the optical apparatus is attachable to a shooting device, and a command signal for a driving operation of the first optical member is input through the shooting device.
In another embodiment, the control means switches operation of the driving mechanism to the first operation mode in response to a start of a driving operation of the first optical member.
In another embodiment, the control means switches operation of the driving mechanism to the first operation mode at a start of an electrical driving operation of the second optical member started in response to a driving operation of the first optical member.
In another embodiment, the control means switches operation of the driving mechanism to the first operation mode in response to a drive control signal for performing electric drive control of the second optical member output in response to a driving operation of the first optical member.
In another embodiment, the driving mechanism comprises a clutch for selectively transmitting a driving force between an electric drive source and the second optical member, and the control means switches the driving mechanism from the second operation mode to the first operation mode by switching the clutch from a disconnected state to a connected state.
In another embodiment, the first optical member is a focus lens unit, the second optical member is a zoom element, and the control means switches operation of the driving mechanism from the second operation mode, in which the zoom element is movable by a manual driving operation to compensate for a variation in angle of view due to a driving operation of the focus lens unit, to the first operation mode, in which the zoom element is movable by an electrical driving operation.
In another embodiment, at least one of the first optical member and the second optical member comprises a diaphragm.
In another embodiment, the apparatus comprises selection means for selectively operating the control means in a first control mode, in which the control means switches operation of the driving mechanism from the second operation mode to the first operation mode in response to a driving operation of the first optical member, and a second control mode, in which the control means does not switch operation of the driving mechanism from the second operation mode to the first operation mode in response to a driving operation of the first optical member.
In another aspect, the present invention relates to an optical apparatus comprising a first movable optical member, a second movable optical member, different from the first optical member, a driving mechanism engaged with the second optical member, and operable in a first operation mode, in which the second optical member is movable by an electrical driving operation, and a second operation mode, in which the second optical member is movable by a manual driving operation, and control means for switching operation of the driving mechanism between the first operation mode and the second operation mode, wherein, when the driving mechanism is operable in the second operation mode, the control means switches operation of the driving mechanism to t
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Perkey W. B.
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