Abstract: Various edge detection arrangements are disclosed, including an edge detection method and arrangement that utilizes outputs of commonly illuminated reference and edge sensors as the inputs for a comparator. The reference sensor is configured to have a wide field of view and the edge sensor is configured to have a narrow, high gain, field of view. Therefore, the reference sensor has a broad signal response to an edge passage and the edge sensor a steep and narrow signal response. When the two signals are biased to cross each other, the comparator output changes state, indicating passage of an edge. Because the reference sensor provides a base signal level directly related to the real time illumination level that the edge sensor also receives, the reference sensor provides a switch point along the transition ramp of the edge sensor that integrates a majority of the random error sources.

Abstract: A quick-release printhead mounting assembly and thermal printer incorporating same, including a printing component, a printer housing, and, a component retention feature attached to or molded into the printer housing adapted for receiving and releasably fixing the printing component to the housing. The retention feature holds the printhead in a fixed position relative to the housing and, therefore, also relative to the platen of the printer. The printing component is advantageously a printhead, such as a thermal printhead, or the combination of a thermal printhead and a heat sink.