Apple is working on technology for upcoming cameras in iPhones, iPod touches, probably the iPad and perhaps other devices. A patent (number 20100238344) for an electronic device having a camera flash redirector has appeared at the US Patent & Trademark Office.
An electronic camera device has an imaging sensor to capture an image of a scene, a flash to illuminate the scene for capture by the sensor, and an evaluator to detect a condition in the scene. A redirector shifts the peak of a spatial energy profile of light from the flash. The peak is shifted from being aimed at one region in the scene to being aimed at another region in the scene, in response to the evaluator having detected the condition in the scene. Other embodiments are also described and claimed in the patent. The inventor is Richard Tsai.
Here's Apple's background and summary of the invention: "In photography, there has been recognized the need for providing flash illumination, at an angle that is suited to the scene coverage of a zoom lens. A zoom lens is capable of a variable range of focus from telephoto to wide-angle settings. Improved image quality may result if the flash illumination angle or spread about the center optical axis of the flash is adjusted to correspond to the scene coverage angle.
"Thus, at the telephoto setting the flash illumination should be well collimated, while at the wide-angle setting, the flash illumination should be spread over a relatively wide angle about the center axis. In such a camera apparatus, the flash itself may have a variable focus lens that is controlled in response to the focus setting of the zoom lens. This may also be described as a flash beam focuser, which focuses the light from the flash into a smaller or a larger area at the center of the frame (center axis of the flash).
"Yet another flash-based technique that may be used to improve image picture quality in certain situations is to vary the power of the camera flash. Somewhat similar to the flash beam focusing technique described above, a variable flash power mechanism may be used to, for example, decrease the light output of the flash when exposure needs to be decreased (due to the flash being too bright). This technique is similar to the flash beam focuser in that it does not shift the angle of the peak of the spatial energy profile of the flash, relative to the center optical axis of the flash.
"An embodiment of the invention is an electronic camera device having an imaging sensor, a flash to illuminate the scene to be captured by the sensor, and an evaluator to detect a condition in the scene. The camera device also includes a redirector that shifts the peak of the spatial energy profile of light from the flash. The peak is to be shifted from being aimed at one region in the scene to being aimed at another region in the scene, in response to the evaluator having detected the condition in the scene. In other words, the angle of the peak of the spatial energy profile is changed, relative to a center optical axis of the flash, so as to increase illumination of, for example, a detected or selected object in the scene.
"In one embodiment, detection of the condition or object in the scene may be performed automatically, through analysis of images captured by the sensor. In addition, or as an alternative, the evaluator can detect the particular condition in the scene based on the output of one or more scene condition sensor devices in the camera (e.g., ambient light sensor and auto focus sensor devices).
"The combination of the flash and the redirector may be composed of a moveable flash lens system that is coupled to a flash light source element, to redirect light from the flash. The evaluator signals the moveable lens system to automatically move (e.g., pivot about an axis), so as to shift the peak of the spatial energy profile of the light. As an alternative, the combination of the flash and redirector may be implemented as a moveable flash light source element that is optically coupled to a fixed flash lens system, again to redirect light, i.e. change the angle of the peak of the spatial energy profile, in response to being signaled by the evaluator.
"In another embodiment, the camera device may have a touch screen, which allows its user to manually select (via finger touch) a dark or dimly lit object or region in the scene, to be illuminated by the combination flash and redirector. The touch screen functions as a viewfinder, showing the scene before the camera. A selection may be made by the user's finger on the touch screen, which is translated to an object or region in an image of the scene. A mapping is performed between the selected object or region in the scene and the closest available angle to which the flash-redirector may be redirected, to illuminate the selected region when taking the picture. In a particular embodiment, the flash is implemented as an array of focused, but fixed light emitting diode (LED) lamps whose power is modulated or otherwise adjusted so as to illuminate the region of interest in the scene, relative to the rest of the scene (during picture taking).
"One or more of the above described embodiments may help make more efficient use of the limited power and energy that is available in a portable electronic device, by limiting light output of the flash and at the same time directing or redirecting the peak of its spatial energy profile to just a subset of the scene (which may be lacking in sufficient natural light but is the primary region or object of interest in the scene). This capability is particularly desirable when, for example, taking video of a person being interviewed, because of the relatively long time interval during which the flash is turned on in such an application.
"The above summary does not include an exhaustive list of all aspects of the present invention. It is contemplated that the invention includes all systems and methods that can be practiced from all suitable combinations of the various aspects summarized above, as well as those disclosed in the Detailed Description below and particularly pointed out in the claims filed with the application. Such combinations have particular advantages not specifically recited in the above summary."