Optical: systems and elements – Lens – With support
Reexamination Certificate
2001-07-16
2003-11-25
Schwartz, Jordan M. (Department: 2873)
Optical: systems and elements
Lens
With support
C359S819000, C359S822000
Reexamination Certificate
active
06654187
ABSTRACT:
FIELD OF THE INVENTION
The disclosed device relates to digital cameras. More particularly, it relates to a device to provide cooperative operative engagement of the lens of a digital camera with the computer chip which digitizes the image communicated from the lens.
BACKGROUND OF THE INVENTION
Conventional photography and film use a lens which focuses the light received through the lens on film which chemically reacts to the light and chemicals used later to produce an image on the film. That image can be converted to a photograph using conventional photo printing methods and the camera produced film negative. The key difference between a digital camera and a film-based camera is that the digital camera has no film. Instead, it has an electronic image sensor that converts light projected upon the image sensor into electrical charges. The ability to produce electronic or printed pictures from photos stored on digital cameras is a direct result of this shift from recording an image on film to recording the image in digital form using the image sensor to take the projected image from a conventional lens and convert it to computer useable format.
The image sensor employed by most digital cameras is a charge coupled device (CCD). Some low-end cameras use complementary metal oxide semiconductor (CMOS) technology. However, the majority of digital cameras employ a CCD as the image sensor to convert the visible image from the lens to a digitized electronic image that may be stored in a computer memory and printed in a variety of fashions.
The CCD is a collection of tiny light-sensitive diodes, which convert photons (light) into electrons (electrical charge). These diodes are called photosites. Each photosite is sensitive to light focused on the CCD surface by the lens and the brighter the light that hits a single photosite, the greater the electrical charge that will accumulate at that site on the photosite on the CCD surface. Consequently, a digital camera is similar to a film camera except that the film is replaced with an electronic image sensor in the form of the CCD.
The electrons produced by the light that hits the individual photosites on the CCD are stored in small capacitors which are read out as a series of voltages which are proportional to the image brightness. This series of rising and falling voltages is then converted to a number by an analog to digital converter and the series numbers are stored and processed by a computer within the camera or communicating with the camera to form the digital or electronic image.
In many designs, a mechanical shutter in the lens field of view is used in the same way that it is used in a film camera—to gate the light that is allowed to reach the CCD. Other cameras use what is called an electronic shutter which allows the control of when the CCD gathers light through electronic control of signals to and from the CCD.
As such, the quality of the light focused by the lens, on the image sensor, whether it be a CCD or CMOS, is of utmost importance to the eventual quality of the digital image produced by the image sensor and stored on the computer or in the camera. It is thus imperative that the light communicated through the lens reach the image sensor at substantially the center point and that the lens axis be substantially perpendicular to the imaging surface of the image sensor. An angle in the lens axis in relation to the image sensing surface will produce unfocused images with one half of the image in focus and the other out of focus. Also, if the center axis of the lens does not substantially line up with the center point of the image sensing surface, the resulting digital image transmitted by the image sensor will be off center, have darker corners or edge portions, and of inferior quality.
Currently, lenses used on digital cameras are placed in lens holders that mate to positions on a circuit board which also mounts the image sensor. The conventional lens holders are affixed in communication with the circuit board using fasteners such as screws and during this fastening process a centering of the lens axis over the center point of the imaging surface of the image sensor is either not controlled, attempted by hand, or estimated using the screw mounting to the circuit board. Unfortunately, due to the tolerances in the mounting of the image sensor and the plurality of planes it can fall into in its attachment to the circuit board, combined with the additional tolerances of mounting the lens holder to a physical mounting on the circuit board around or adjacent to the image sensor and at potentially different planes, it is extremely hard to place the center axis of the lensholder-mounted lens, centered on the center point of the imaging surface and also perpendicular to that surface. Consequently, much hand adjustment by persons mounting the lens to the board is required and many assembled components fail to produce an adequate digital image due to misalignment caused by the multiple tolerances in lens attachment to the board and image sensor attachment to the same circuit board.
As such, there is a pressing need for a device which will cooperatively engage the lens used with a digital camera and operatively mount that lens with its center axis lined up with the center point of the imaging surface on the image sensor. Such a device should also maintain the lens center axis substantially perpendicular to the imaging surface of the image sensor and also provide a means to adjust the distance between the projection end of the lens and that imaging surface for focus of the projected image on the imaging surface. Still further, such a device should allow for easy attachment of the lens to the image sensor instead of the circuit board with little or no need for adjustment during manufacture.
SUMMARY OF THE INVENTION
The above problems, and others are overcome by the herein disclosed and described lens carrier for cooperative operative engagement with the image sensor such as a CCD or CMOS device, or a chip carrier holding the image sensor to a circuit board surface.
The camera lens carrier herein described and disclosed features a base having a barrel having an axial channel therethrough attached to the base and communicating therethrough. The lens barrel is configured to cooperatively engage the exterior of a camera lens. The cooperative engagement allows for a threaded or other laterally translatable adjustment of the distance inside the barrel in which the lens protrudes and therefor the distance that the projection end of the lens is mounted above the base.
The center axis of the barrel is also positioned to line up substantially with the center point on the imaging surface of the image sensor to be used in combination herewith. Consequently, the image projected by the lens is centered on the imaging surface once the lens carrier is cooperatively engaged with the image sensor or the chip carrier holding the image sensor used in combination herewith.
The bottom surface of the base is configured for cooperative engagement with the edge of the image sensor used to capture the lens-projected image. This edge in generally substantially parallel to the imaging surface of the image sensor itself and therefor a cooperative engagement with the edge will yield a parallel engagement of the base with the imaging surface. Since the base is perpendicular to the lens barrel, the lens when cooperatively engaged in the lens barrel with the base cooperatively engaged with the edge of the image sensor will place the lens center axis lined up with the center point of the imaging surface and perpendicular to the imaging surface to yield optimum optical clarity. This cooperative engagement of the base of the lens carrier thereby yields a means for perpendicular alignment of the lens axis with the imaging surface of the image sensor.
A means to focus the image projected by the lens on the imaging surface is provided by the cooperative laterally adjustable engagement of the lens barrel with the lens and the ability of that cooperative engagement to adjust the dist
Harms Donn K.
Schwartz Jordan M.
Stultz Jessica
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