Optical: systems and elements – Lens – With variable magnification
Reexamination Certificate
1998-04-17
2001-03-27
Mack, Ricky (Department: 2873)
Optical: systems and elements
Lens
With variable magnification
C359S696000
Reexamination Certificate
active
06208472
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a lens drive control device and an image pickup apparatus using the lens drive control device and, more particularly, to a lens drive control device and an image pickup apparatus suited for use in small-sized electronic still cameras (e.g., digital cameras) having an image pickup element such as a CCD (charge-coupled device).
2. Description of Related Art
In recent years, the image pickup apparatus using an image pickup element such as a CCD have been widespread in the form of video cameras or electronic still cameras. These image pickup apparatus are capable of taking and storing a video image with ease. The stored video image can be viewed on the CRT (cathode-ray tube) or like display device or printed out as photographs.
However, the conventional video camera and electronic still camera trend is to take over the system of the silver-halide film camera without any considerable alteration. For the electronic still camera, some disadvantages arise in employing all the features of that system.
For example, lens drive systems which prevail in the lens-shutter-type silver-halide cameras have a common feature that, when switched from the non-shooting mode where the lens barrel is retracted into the camera body to the shooting mode, the zoom lens is driven to the wide-angle end in response to turning-on of the electric power supply. On the contrary, for the small-sized electronic still camera, there are occasions that such an initial setting is unfavorable.
An appropriate type of optical system to the small-sized electronic still camera is the negative lead type of zoom lens in which the front lens unit is negative in refractive power and the rear lens unit is positive in refractive power. In some cases, the physical length for the wide-angle end of the negative lead type of zoom lens becomes longer than for the telephoto end. With the zoom lens of such a form, when the electric power supply is turned on, it results that the initial setting process of the zoom lens goes to the wide-angle end after having once passed across the telephoto end. On the contrary, the electronic still camera has a feature that the telephoto end is rather more often enjoyed than the wide-angle end. This is because, when the electronic still camera is used as a document camera to read documents into the computer or to shoot personal name cards, the telephoto end is usually used at which the distortion is lesser than at the wide-angle end.
On consideration of such a usage of the electronic still camera, it is not always necessary to take the initial setting in the wide-angle end in response to turning-on of the power supply. Also, in the lens configuration described above, the initial setting process overruns the telephoto end which is rather high in the frequency of use. Therefore, the zoom lens is apt to be driven wastefully, thereby causing the premature consumption of the battery.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to provide a lens drive control device which prevents the lens from being driven wastefully when the electric power supply is turned on, and an image pickup apparatus using the lens drive control device.
To attain the above object, in accordance with an aspect of the invention, there is provided a lens drive control device, which comprises a zoom lens, drive means for driving at least one lens unit which constitutes the zoom lens, control means for controlling the drive means, and a switch for switching between a shooting state and a non-shooting state of the zoom lens, wherein, when the zoom lens is switched from the non-shooting state to the shooting state by the switch, the control means causes the drive means to drive the zoom lens to a zoom position other than a wide-angle end.
In accordance with another aspect of the invention, there is provided a lens drive control device, which comprises a zoom lens in which a distance between a lens surface closest to an object side and a lens surface closest to an image side becomes minimum in a predetermined zoom position other than a wide-angle end, drive means for driving at least one lens unit which constitutes the zoom lens, control means for controlling the drive means, and a switch for switching between a shooting state and a non-shooting state of the zoom lens, wherein, when the zoom lens is switched from the non-shooting state to the shooting state by the switch, the control means causes the drive means to drive the zoom lens to the predetermined zoom position.
In accordance with a further aspect of the invention, there is provided a lens drive control device, which comprises a zoom lens, drive means for driving at least one lens unit which constitutes the zoom lens, control means for controlling the drive means, a switch for switching between a shooting state and a non-shooting state of the zoom lens, storage means for storing a zoom position taken when the zoom lens has been switched from the shooting state to the non-shooting state by the switch, and command means for issuing a command to read out the zoom position stored in the storage means, wherein, when the zoom lens is switched from the non-shooting state to the shooting state by the switch, if the command to read out the zoom position stored in the storage means is issued by the command means, the control means causes the drive means to drive the zoom lens to the zoom position stored in the storage means.
In accordance with a still further aspect of the invention, there is provided an image pickup apparatus having the lens drive control device described above.
These and further aspects and features of the invention will become apparent from the following description of preferred embodiments thereof taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4847648 (1989-07-01), Yamaguchi et al.
patent: 5111226 (1992-05-01), Nakamura et al.
patent: 5270766 (1993-12-01), Nakamura et al.
patent: 5819120 (1998-10-01), Hamada et al.
Canon Kabushiki Kaisha
Mack Ricky
Robin Blecker & Daley
LandOfFree
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