Patent Application
20070258002
Recent advances in digital imaging technology have made consumer electronic devices such as digital still cameras, digital video cameras, digital image scanners and the like more accessible to a greater number of consumers. As a result, for each such type of device, a significant number of manufacturers typically compete to produce equipment exhibiting a combination of price, performance, and functionality most appealing to potential customers.
Many of these imaging devices employ some type of two-dimensional photosensitive cell (or photocell) array to capture one or more images of interest to a user of the device. One example of a photocell array is included in a charge coupled device (CCD). A CCD typically contains thousands or millions of photocells or picture elements (“pixels”), each of which accumulates an electrical charge proportional to the intensity of light incident upon the pixel. Thereafter, each of these electrical charges is retrieved in a serial fashion and converted to a number indicative of the light intensity. Collectively, the numbers associated with each pixel thus represent an image as received by the CCD.
To yield a useful image, a lens similar to that utilized in legacy photographic film cameras is employed to focus the light received by the device onto the CCD or other photocell array. Typically, the lens used is an inversion lens, which inverts the light received by the lens prior to projecting the light onto the array, resulting in an inverted image. Based on this structure, the CCD and surrounding circuitry are organized so that the charge accumulated by each pixel is read in an order beginning with the upper-left corner of the image, and then proceeding from left to right across each row of pixels, one row at a time, ending at the lower-right corner of the image. This order is normally compatible with displaying the image on a display, printing the image, and so forth.
Recently, some digital imaging devices have begun employing reflection or mirror lenses in lieu of simple inversion lenses. Reflection lenses normally employ one or more mirrors to bend or fold the path of the received light within the device before encountering the CCD. Reflection lenses are often utilized to increase the effective focal length of the lens, resulting in the ability to provide telephoto, or magnification, capability, while maintaining a small form factor for the imaging device.
However, due to the changes in the light path caused by a reflection lens, the orientation of the image is often different from that created by an inversion lens. As a result, the CCD or other photocell array may retrieve the accumulated charge from each pixel in an order different from that typically expected. For example, the image may be retrieved beginning with the upper-right or lower-left corner, as opposed to the upper-left corner, thus complicating further display or printing of the image. While the image may be processed to yield the more standard pixel order, such processing requires significant bandwidth and other resources of the device that could be more advantageously employed performing other tasks.
Also included in the imaging subsystem 100 is a bidirectional shift register 108 that is configured to receive the pixel data from the first 107 of the rows 106 of the array 101 and shift the pixel data toward either a first end 109 or a second end 111 of the bidirectional shift register 108.
As will be described in greater detail below, various embodiments of the invention may be employed to supply an imaging device with an imaging subsystem that allows the use of any of multiple lens configurations while delivering the pixel data to the device in a consistent order.
In one embodiment, the imaging subsystem 100 may also include a first amplifier 110 configured to amplify the pixel data shifted from the first end 109 of the bidirectional shift register 108, and a second amplifier 112 configured to amplify the pixel data shifted from the second end 111 of the bidirectional shift register 108. This amplification may allow other portions of the imaging device to more readily process the pixel data describing the captured image.
In another implementation, the array 101 is a CCD array, wherein the imaging pixels 102 are photocells. As a result, the pixel data of each of the imaging pixels 102 is an electrical charge related to an intensity of light received by the imaging pixel 102. This charge is the pixel data representing a portion of an image being captured by the imaging device. In other embodiments, other arrays of imaging pixels employing a different technology may be used to collect and image visible light. Technologies for detecting infrared frequencies, ultraviolet frequencies, and other portions of the non-visible electromagnetic spectrum may be utilized in yet other embodiments.
In one implementation of a CCD, the array 101, the bidirectional shift register 108, and the first and second amplifiers 110, 112 are all fabricated onto a single portion of silicon or other substrate to efficiently transfer the charge related to the light captured by the array 101 to the bidirectional shift register 108 and the amplifiers 110, 112 before the associated data is received and processed by the remainder of the imaging device.
While single imaging pixels 102, each related to a particular portion of an image, are discussed herein, such a discussion does not preclude embodiments which employ arrays 101 in which multiple pixels 102 are associated with a particular area of the image. For example, color CCDs often employ at least three pixels, each sensitive to a particular color, such as red, blue or green, for each identifiable portion of an image.
In some implementations, the number of imaging pixels 102 in the array 101 may number in the thousands or millions. In other embodiments, fewer or more imaging pixels may be utilized, depending on the desired level of resolution for the corresponding imaging device.
The imaging subsystem 100 may be employed in a variety of imaging devices, including but not limited to digital still cameras, digital video cameras, and digital image scanners. Also, any device designed to capture images, but whose primary function is not image-related, such as a cell phone, may benefit from application of the various embodiments described herein.
Shown in
Generally, the imaging device itself provides the frame of reference by which the various portions of the image are identified. For example, with respect to a digital still camera or a digital video camera, how a user of a device views the image by way of a standard view finder or a liquid crystal display (LCD) incorporated into the device typically determines how the image is received into the device. Thus, the upper-left corner of the image as viewed by the user, and as shown in
To more fully explain the foregoing embodiments,
In a first example depicted in
In
Finally,
In the embodiments discussed above, the array 101 and the bidirectional shift register 108 are oriented relative to the imaging device such that the corner of the image 300 selected for first transfer from the imaging subsystem 100 is located near the first row of the array 101. Also, the bidirectional shift register 108 is configured to shift its pixel data toward its end located near the selected image corner so that pixel data associated with that corner is shifted out first. With respect to
In one embodiment, the bidirectional shift register 108 is configured to accept at least three different clock phases to allow efficient shifting of electrical charge into the bidirectional shift register 108, and toward either the first end 109 or the second end 111 of the shift register 108. Unidirectional shift registers typically only require two clock phase inputs, as electrical charge may only be shifted toward one end of such a register.
Various embodiments of the present invention provide a single imaging subsystem which can assume several configurations for adapting to a variety of lens types which invert and reflect an image any number of times. As mentioned above, some newer imaging devices currently utilize reflection or mirror lenses in lieu of simple inversion lenses to extend the effective local length of the device without increasing the size of the device. To this end, the reflection lens normally includes one or more mirrors to bend or fold the optical path of the received light within the device prior to the light encountering the array of imaging pixels. In so doing, however, the image is likely to be oriented relative to the array differently from that identified with a simple inversion lens, due to any number of inversions and/or reflections of the image resulting from the lens. Employing the configurations shown herein, the imaging subsystem allows a selectable order of transfer of the generated pixel data from the imaging subsystem for use by the remainder of the associated imaging device. In many cases, this order reduces or eliminates reordering of the image prior to subsequent processing by the device, thus conserving processing bandwidth and other resources of the imaging device that may be utilized for other tasks.
While several embodiments of the invention have been discussed herein, other embodiments encompassed by the scope of the invention are possible. For example, while some embodiments of the invention are described above in conjunction with primarily consumer-oriented applications, such as digital still and video cameras, other types of imaging equipment designed substantially for industrial, scientific, commercial and other markets may also benefit from application or adaptation of the various embodiments, as presented above. Also, while many directional references are made herein (e.g., left, right, upper, lower, and so on), these references are provided merely as an aid to understanding the specific embodiments described herein, and thus do not limit or prohibit the use of other embodiments utilizing differing directional reference frames. Further, aspects of one embodiment may be combined with those of alternative embodiments to create further implementations of the present invention. Thus, while the present invention has been described in the context of specific embodiments, such descriptions are provided for illustration and not limitation. Accordingly, the proper scope of the present invention is delimited only by the following claims.
