TV camera lens device

Television – Camera – system and detail – Optics

Reexamination Certificate

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Details

C348S352000, C396S079000, C396S132000, C359S693000, C359S705000

Reexamination Certificate

active

06271882

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a TV camera lens device, and more particularly to a technique of controlling a TV camera lens which is capable of forming an optical system in which a macro-shooting can be performed by moving the whole of a master lens group or a part thereof along an optical axis.
2. Description of Related Art
In a zoom lens applied in a broadcast TV camera, one of the whole of a master lens group in a taking lens system and a part of the master lens group is moved forward and backward along the optical axis to adjust the flange back length, thereby forming a sharp image of an object on a picture screen. Japanese Patent Publication Nos. 58-1401 and 60-46405 disclose TV camera lenses in which the master lens group, which is the identical master lens group that is moved forward and backward along the optical axis to adjust the flange back length, is moved forward and backward along the optical axis to form an optical system for the macro-shooting.
Further, such TV camera lenses are known where the master lens group is divided into two groups including a macro lens group, which is moved and controlled during the macro-shooting, and another lens group for adjusting the flange back length, which is moved and controlled during the flange back length adjustment. During the macro-shooting, the macro lens group, which is a part of the master lens group, is moved and controlled. During the flange back length adjustment, the lens group for adjusting the flange back length, which is a part of the master lens group, is moved and controlled.
In general, a rotary adjustment knob is provided on one side of the mount frame (the right side viewed from the front, i.e. the left side of a user) so that rotational force of the adjustment knob can be transmitted to a master lens driving mechanism in a lens mount via a power transmission mechanism such as an assembly of gears. If the user turns the adjustment knob by hand, an image formation position of the TV camera lens can be finely adjusted and the macro-shooting can be performed.
In the TV camera lens in which the master lens group is moved to perform both the flange back length adjustment and the macro-shooting, however, since the normal shooting is usually performed after the flange back length adjustment is completed, and a knob or the like is operated on demand to changeover to the macro-shooting, there is a problem that the operation becomes troublesome. Further, it is difficult to correctly return the master lens group to the initially-adjusted position of the proper flange back length when the shooting is switched from the macro-shooting to the normal shooting.
Similarly, also in the TV camera lens in which the macro lens group or the lens group for adjusting the flange back length, both of which are parts of the master lens group, is moved and controlled, respectively, to perform the macro-shooting or the flange back length adjustment, it is necessary to correctly return the macro lens group to the initially-adjusted position, particularly to the normal shooting position in the balance with the flange back length adjustment, when the macro lens group is moved to a macro-shooting position or a normal shooting position.
Furthermore, since it is desirable that the flange back length is precisely adjusted, the flange back length is frequently adjusted every time the shooting is performed. As for the macro position, there are such characteristics that a standard macro position is preset on manufacturing and the adjustment in focusing can be performed by a zoom lens.
SUMMARY OF THE INVENTION
The present invention has been developed in view of the above described circumstance and has as its object the provision of a TV camera lens device, which is capable of correctly moving a master lens group to a preset macro position during the macro-shooting after adjusting a flange back length and capable of correctly and repeatedly returning the master lens group to a once adjusted position of a proper flange back length after the macro-shooting.
To achieve the above-described object, according to the present invention, a TV camera lens device in which one of the whole of a master lens group arranged in a lens mount and a part of the master lens group is moved forward and backward along an optical axis whereby an optical system capable of performing a macro-shooting can be formed, and a macro position, at which the one of the whole of the master lens group and the part of the master lens group is positioned during the macro-shooting, is preset, the driving device comprises: a macro control signal generating device for outputting a macro control signal for moving the one of the whole of the master lens group and the part of the master lens group to the preset macro position; and a lens driving device for moving the one of the whole of the master lens group and the part of the master lens group forward and backward along the optical axis in accordance with the macro control signal from the macro control signal generating device.
According to the present invention, in performing the macroshooting, the whole of the master lens group or a part thereof can be moved to the preset macro position in accordance with the macro control signal.
The TV camera lens device of the present invention further comprises: a flange back length control signal generating device for outputting a flange back length control signal for moving the whole of the master lens group to a position of a proper flange back length in accordance with an operation of an external operating member; a selecting device for selecting the performance of the macro-shooting; and a control changeover device for invalidating the flange back length control signal from the flange back length control signal generating device and making the lens driving device controllable in accordance with the macro control signal from the macro control signal generating device in a case where the performance of the macro-shooting is selected by the selecting device, and for invalidating the macro control signal from the macro control signal generating device and making the lens driving device controllable in accordance with the flange back length control signal from the flange back length control signal generating device in a case where the performance of the macro-shooting is not selected by the selecting device.
With this arrangement, the flange back length control signal generating device for instructing the position of the proper flange back length and the macro control signal generating device for instructing the macro position are provided separately from one another, whereby the position of the proper flange back length and the macro position can be set independently of one another. The flange back length can be suitably adjusted by operating the external operating member while a state of focusing is confirmed by a view finder or the like every time the shooting is performed. As for the macro position, the standard macro position is preset on manufacturing or the like, and the fixed macro position which is preset is instructed by the macro control signal generating device. Then, depending upon the operation of the selecting device, out of those including the flange back length control signal generating device and the macro control signal generating device, either one control signal from the two means is validated and the other is invalidated.
That is, at the time of adjusting the flange back length, a command from the flange back length control signal generating device is validated by device of the selecting means, and the master lens group is adjusted to the position of the proper flange back length by operating the external operating members. Thereafter, at the time of macro-shooting, a command from the macro control signal generating device is validated by means of the selecting device, and the master lens group is moved to the preset macro position. At this time, the flange back length control signal generating device retains the state of

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