Optical unit

Details Optical unit Optical unit

2003-01-21

2004-10-12

Dang, Hung Xuan (Department: 2873)

Optical: systems and elements

Lens

With support

C359S824000

Reexamination Certificate

active

06804068

ABSTRACT:

CROSS REFERENCE TO RELATED APPLICATION
This application claims benefit of Japanese Patent Application No. 2002-011902 filed on Jan. 21, 2002, the contents of which are incorporated by the reference.
BACKGROUND OF THE INVENTION
The present invention relates to optical units and, more particularly, to optical units utilized for cameras and the like.
Heretofore, so-called electronic cameras such as film cameras, electronic still cameras and video cameras have been put to practical use and widely spread, which are constructed such that, a foreground object image formed on the basis of a light flux of a foreground object (hereinafter referred to as foreground object flux) which is incident on an imaging optical system having a plurality of optical elements (or lens groups) and other elements, is focused on the light-receiving surface of a foreground object image obtaining means, such as a photographic imaging film or a charge coupled device (abbreviated CCD), disposed at a predetermined position, thereby obtaining a desired foreground object image and recording the same image in a predetermined form.
Such prior art film cameras and electronic cameras (both types of cameras being hereinafter generally referred to as cameras), are usually constructed to have an optical unit having an imaging optical system or an optical element (constituted by a plurality of lenses (hereinafter referred to as lens unit) for focusing the foreground object image on a predetermined position.
Usually, such a camera is brought outdoors by the user for use. Thus, importance has hitherto been attached to the portability of the cameras, and more and more thickness and size reduction of the camera itself has been demanded.
In recent years, electronic cameras which are constructed with a main aim of obtaining electronic still image data are being rapidly spread. Such electronic cameras usually comprise various constituent parts such as a circuit substrate, which is a member constituting part of a lens unit, and on which are mounted, for such purposes as zooming operation and focus adjusting operation, drive mechanism and actuators for causing movement of an optical element constituting an imaging optical system (hereinafter referred to as lens group) in predetermined directions as well as electric circuit for controlling these drive mechanisms and actuators.
This means that size reduction of the camera itself calls for adequately disposing constituent parts of the camera in the inside thereof while also taking the size reduction of the individual constituent parts into considerations.
As for lens units in prior art cameras, those of various forms are well known in the art, for instance one, in which in order to lead a foreground object light flux incident in the camera inside via a plurality of lens groups to a light-receiving surface of an imaging element or the like, a predetermined reflecting means such as a reflector or a prism is disposed in the optical path to let the optical path of the foreground object light flux be bent in a predetermined direction, for instance a direction substantially perpendicular to the incident light flux axis.
As the lens unit adopting so-called bending optical system as above, various proposals are made in various literatures such as Japanese Patent Laid-Open No. 2001-75162.
In the lens unit disclosed in the above Japanese Patent Laid-Open No. 2001-75162, a reflecting means for bending the optical axis of the foreground object light flux to a substantially perpendicular direction is disposed in the optical path of an imaging optical system, which transmits the foreground object light flux, thereby realizing size reduction of the electronic camera itself while securing an optical path length necessary for obtaining the image.
As shown, adopting the so-called bending optical system with a reflecting means or the like disposed in the optical path in the imaging optical system of electronic camera, can be thought to be very advantageous means for realizing the size reduction of the electronic camera itself.
In the meantime, in prior art cameras, wide use is made of small size stepping motors and DC motors (hereinafter merely referred to as small size motors) as actuators for individually driving respective lenses, which contribute to the zooming and focus adjusting operations, among the plurality of lenses constituting the imaging optical system.
However, when a usual actuator such as a small size motor is utilized for driving the lenses contributing to the zooming and focus adjusting operations, a problem is posed that a drive power transmitting mechanism for transmitting rotational drive power to the small motor is complicated.
Specifically, for carrying out the zooming and focus adjusting operations, predetermined lens groups have to be moved straight in directions among the optical axis of the imaging optical system. This means the need for a drive power transmitting mechanism for transmitting drive power from the small size motor as drive source to the zooming and focus adjusting lenses as driven members and also a drive power converting mechanism for converting the driving direction of the drive power.
The drive power transmitting and like mechanisms are usually constituted by gears. These gears or like constituent parts should be mechanically accurately manufactured to ensure reliable and loss-free drive power transmission to the driven members.
However, the camera which size reduction is demanded for, has a problem that accurate and inexpensive mass production is subject to difficulties. This means that for constructing a smaller size drive power transmitting mechanism, higher precision machining techniques are necessary, leading to the tendency of manufacturing cost increase.
Also, with the drive power transmitting or like mechanisms that are constructed with gears or the like, drive power is mechanically transmitted. Therefore, the drive power transmission is inevitably subject to drive power losses. Also, drive noise can not be perfectly suppressed.
Furthermore, in the usual camera, secondary batteries of low power capacity such as dry cells and lithium cells are usually used as the drive power supply. Saving of consumed power, is thus required for the electric constituent parts provided in the camera.
However, small size motors usually used as drive power supply of prior art cameras have a problem that high drive power is required. For example, small size motors usually used in cameras require power of 3 V/300 mA (i.e., roughly 1 W).
In prior art cameras, the control system of the camera is usually contrived such as to reduce the drive time of the small size motor for preventing wasteful power consumption. As an example, it is contrived to control the focus adjusting operation (i.e., AF operation) to be executed when and only when required at the time of imaging and also to control the focus adjusting and zooming operations such as not to be executed at the same time. Such controls tend to prolong the operation time as required for a series of imaging operations. This tendency leads to a problem of prolonging the time lag between the time when the shutter release button of the camera is actually operated by the user and the time when the shutter is actually driven for the exposure operation.
As shown above, in the case of utilizing the prior art small size motor or the like as the drive power supply (or actuator) in the camera, limitations are imposed on the size reduction and power saving of the camera.
In recent years, as the drive power source (or actuator) to be used in super-small size precision machines or the like, various types of actuator which are in different drive systems from the small size motor noted above are being developed.
For example, electrostriction actuators are described in “2000 Micro-Machine Technique Research and Development (Power Generation Equipment High Performance Maintenance Technique Development) Commission Research Result Reports”, Foundation Micro-Machine Center, March, 2001.
FIG. 17
is a view schematically showing the constructio

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