This patent application is assigned to
The following quote was obtained by the news editors from the background information supplied by the inventors: "This invention relates generally to cameras, and more particularly to very small electronic camera modules. Even more particularly, the invention relates to a device and method for manually adjusting the focal field in small electronic camera modules.
"Cameras in general, and digital camera modules in particular are well known. Digital cameras commonly incorporate means for adjusting the focal field in order to allow a user to take sharp photos of close up objects, such as business cards or bar codes, as well as distant objects, such as landscapes or people.
"In some cameras, the focal field is continuously adjustable over a predefined range. For example, the lens is mounted to a guide so that it can be displaced along the optical axis by an electrical or mechanical drive.
"While continuously adjustable lens mechanisms facilitate precise focus at virtually any focal distance in the range, their complexity introduces a variety of disadvantages. One disadvantage is that electrical drive units require power, which shortens battery life. Another disadvantage is the increased number of parts and required assembly time, both of which contribute to the overall cost of the camera. The complexity also increases possible sources of failure and, therefore, results in a decreased reliability for the camera. Yet another disadvantage is that the complexity of the device increases the overall size of the camera.
"In mid to lower quality cameras, many of these disadvantages can be at least partially alleviated by replacing the continuously adjustable lens mechanism with a lens mechanism that can be manually transitioned between a plurality of discrete focal positions. Because the lens is moved manually by the user between the various focal positions, the drive motor, linkages, etc. are unnecessary. Further, providing a plurality of discrete focal positions is beneficial, because it eliminates the need to focus the lens for each picture. Thus, a user can take average quality images with minimal effort and experience. Indeed, many digital images that are taken are relatively disposable and do not require a high quality image. For example, taking a picture of a phone number or an address on a business card does not require a very high quality photo, as long as the letters and/or numbers are legible.
"Despite the advantages provided by the multiple discrete position, manually operated focus mechanism, this type of mechanism has not been successfully implemented in miniature camera modules, such as camera modules now incorporated into cellular telephones, hand-held personal digital assistants (PDAs), and the like. Problems arise due to the extremely small size of such camera modules. For example, the components of miniature camera modules are many times smaller than a user's finger and are, therefore, difficult to manipulate. Further, the small components are fragile, and can be easily broken when being directly manipulated by a user. Further, the camera modules should be able to be mounted directly on a circuit board of the main device (cell phone, PDA, etc.), therefore access to the module is somewhat limited. Yet another problem is that it would be difficult to see what position the small lens is in at any given time. Yet another problem is that the camera modules must compete with the host device for allocated space, so focus mechanisms that require extra space would be considered a disadvantage. For any one or more of these reasons, or other reasons, known miniature camera modules do not include user adjustable focus mechanisms, or at least do not include such modules that do not suffer from one or more of the above described disadvantages.
"What is needed, therefore, is a miniature camera module, with a user adjustable focus mechanism, that is more compact. What is also needed is a miniature camera module, with a user adjustable focus mechanism, that requires fewer components to function. What is also needed is a miniature camera module, with a user adjustable focus mechanism, that minimizes points of possible failure. What is also needed is a miniature camera module, with a user adjustable focus mechanism, that requires a shorter assembly time and is less expensive to manufacture. What is also needed is a miniature camera module, with a user adjustable focus mechanism that is easy for a user to manipulate manually. What is also needed is a miniature camera module, with a user adjustable focus mechanism, that provides clear indicia of the current focal position of the lens."
In addition to the background information obtained for this patent application, VerticalNews journalists also obtained the inventors' summary information for this patent application: "The present invention overcomes the problems associated with the prior art by providing a camera module that can be manually switched between a plurality of discrete focal positions. The camera module is very compact, yet facilitates user adjustment of the focal distance.
"The camera module includes a housing, a lens assembly, and a carrier. The carrier includes a first focusing feature for adjustably engaging the lens assembly and a second focusing feature for adjustably engaging the housing. In the particular embodiment shown, the carrier is a sleeve formed from a substantially cylindrical shell that includes an inner wall, an outer wall, a top surface, and a lower surface. The inner portion of the sleeve includes a portion of the first focusing feature (e.g., threads, ramps, channels, etc.), and the outer wall of the sleeve defines the second focusing feature. In the specific example shown, the second focusing feature is a sloped channel that is engaged by a pin fixed to the housing. The channel extends from the lower portion of the sleeve to and through the upper surface of the sleeve such that the channel does not include an upper boundary. The channel defines the rotational limits of the sleeve and includes at least two detents that define different focal positions. In the particular embodiment described, the detents are spaced apart depressions formed in the channel that each provide a discrete, stable resting position for an associated engaging pin. The channel includes an intermediate portion that is relatively higher than the depressions, so that the pin is urged toward on of the depressions or the other.
"The example housing shown includes a substantially rectangular base with side walls extending upwardly therefrom. A portion of the side walls form legs extending upwardly from the corners of the base. Two of four legs include apertures through which retaining pins pass to engage the channel of the sleeve. The two legs that receive pins are positioned near opposite corners of the base. The inner portions of the legs are rounded to match the contour of the cylindrical sleeve. Forming legs near the corners of the base contributes to a reduction in the size of the camera module such that the width of the housing base can be as small as the outer diameter of the sleeve.
"In the example embodiment shown, a biasing member is disposed between the sleeve and the housing. The biasing member is a resilient, tapered ring. The bottom portion of the sleeve is tapered so as to have a similar contour to the inner portion of the biasing member. Optionally, the biasing member is an o-ring and the bottom of the sleeve defines a seat for the o-ring.
"The housing is mounted to a substrate over an image capture device also mounted on the substrate. The example housing shown is mounted via a plurality of posts extending from the bottom of the base of the housing. The posts are fixed within apertures formed in the substrate for that purpose. An optional switch (mechanical, optical, magnetic, etc.) is also mounted to the substrate. The switch engages a portion of the sleeve and generates a signal indicative of the sleeve's rotational position. A portion of the housing surrounds the switch to protect it from accidental impact.
BRIEF DESCRIPTION OF THE DRAWINGS
"The present invention is described with reference to the following drawings, wherein like reference numbers denote substantially similar elements:
"FIG. 1 is a perspective view of a camera module in a first discrete focal position;
"FIG. 2 is a perspective view of the camera module of FIG. 1 in second discrete focal position;
"FIG. 3 is an exploded view of the camera module of FIG. 1;
"FIG. 4 is a perspective view of a lens assembly of FIG. 2 within a sleeve of FIG. 2;
"FIG. 5 is a side view of the sleeve of FIG. 4;
"FIG. 6 is a cross-sectional view of a biasing member of FIG. 3;
"FIG. 7 is a partially exploded view of a manual adjustment device for engaging the sleeve of FIG. 4;
"FIG. 8A is a top plan view of the camera module of FIG. 2;
"FIG. 8B is a top plan view of an alternate camera module;
"FIG. 9A is a cross-sectional view of the camera module of FIG. 8A taken along line A-A of FIG. 8A;
"FIG. 9B is a cross-sectional view of the camera module of FIG. 8B taken along line A-A of FIG. 8;
"FIG. 10 is a flow chart summarizing a method for assembling a camera module according to one aspect of the present invention;
"FIG. 11 is a flow chart summarizing a method for mounting a carrier within a housing;
"FIG. 12 is a flow chart summarizing a method for adjustably mounting a lens assembly to a carrier; and
"FIG. 13 is a flow chart summarizing a method for focusing a lens assembly."
URL and more information on this patent application, see: Toor, John W.; Bogue, Elaine B.; Cargill, Ellen B.;
Keywords for this news article include:
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