A first embodiment of an illumination source including red LEDs, green LEDs, and blue LEDs provides illumination for a scanner. The LEDs are arranged in an array to generate spectrally and spatially substantially uniform illumination on the surface of an object, such as printed media, which is to be scanned. The arrangement of LEDs includes a plurality of groups of three LEDs. Each group of LEDs includes a red LED, a green LED, and a blue LED. The LEDs of like colors are connected in series. Power is supplied to the three groups of series connected LEDs by three current sources. The three current sources are each configured to supply a constant current to one of the groups of series connected LEDs. Each current source supplies a magnitude of current so that the resulting light provides substantially uniform illumination on the printed media. A second embodiment of the illumination source includes LEDs that can each generate light having a substantially uniform energy spectrum over the range of visible light frequencies. A third embodiment of the illumination source includes a plurality of groups of four LEDs. Each of the groups of LEDs includes a red LED, a green LED, a blue LED, and a yellow LED.
An LED arrangement which produces a color temperature adjustable white light. The LED arrangement includes one or more white LEDs and a first drive circuit operable to supply a first drive current to the one or more white LEDs such that a white light is output at a desired intensity. The LED arrangement further includes one or more colored LEDs arranged such that a light output from the one or more colored LEDs combines with the white light to produce a resultant light having a desired color temperature. The colored LEDs are driven by a second drive circuit which supplies a second drive current to the one or more colored LEDs such that a colored light is output at a desired intensity, the intensity of the colored light output from the one or more colored LEDs being adjustable so as to adjust the color temperature of the resultant light.
Exemplary methods, apparatuses, media, and arrangements enable the implementation of one or more features in electronic devices that have (e.g., display) screens that are capable of light emission and detection. These features include, for example, scanning, (simulated) touch-screen sensitivity, and ambient light determination and compensation. The display screens may be comprised of light emitting/detecting elements, such as diodes, that can emit light for visual display and can detect light for receiving light information data. In certain described implementations, a method for implementing a feature using a display screen with emitting/detecting elements includes the actions of: activating multiple elements of an array of elements to emit light; activating multiple elements of the array of elements to detect light; producing detected light data representing the light detected by the multiple elements that are activated to detect light; and processing the detected light data to implement the feature.
A light source incorporates light emitting diodes (LEDs). The LEDs may be raised off the floor of the optical cavity to permit light to be emitted from the base of the LED. Additionally, a reflective protrusion may be placed beneath the raised LED to aid in redirecting light forward. The LEDs may be skewed in relation to adjacent LEDs to reduce interference. Non-white LEDs may be incorporated into the light source to permit for selective color tuning. Fluorescent lamps may also be implemented in combination with the LEDs to form a hybrid light source.
A method and apparatus for adjusting, on a pixel-by-pixel basis, the gain and offset in an AFE as the pixels are sequentially processed. Although the method can be used for any purpose, it is directed in particular to light source non-linearity, such as edge effects of a scanner. A unique clocking method clocks the gain and offset values into the register at a higher clock rate than the image sampling rate.
An optical object detector including a feed path, a reference pattern facing the feed path, and an optical sensor configured to view the reference pattern through the feed path, absence of the reference pattern from the view of the optical sensor indicating presence of an object in the feed path.
