Many electronic devices include one or more components that emit light and one or more sensors that receive the emitted light. In some cases, the sensor may detect that light once it has been reflected from a surface that is external to the device. An emitting component (e.g., a light emitting diode (LED), a semiconductor laser, etc.) may be quite small. A sensor component, which may also be quite small, typically includes an integrated circuit (IC) chip having an array of photo-sensitive elements. Correctly positioning the emitting and sensing components is often crucial to proper operation of the device.
One example of a device employing emitting and sensing components is a computer mouse. In some designs, for example, a sensor (e.g., an imaging array) generates data for successive portions of a desk top or other external surface over which the mouse is moved. A processor in the mouse compares that data and determines the direction and distance of movement. The emitter (an LED or laser) must be positioned so that light is cast on the portion of the external surface from which the sensor captures reflected light. In many cases, it is beneficial or necessary to orient the emitter so that light strikes the external surface at an angle. In turn, this may require positioning the emitter at a particular angle relative to a printed circuit board (PCB) or other structure within the mouse.
FIG. 1 schematically shows one of several manners in which a desired orientation has typically been achieved. Main PCB A is internally attached to a housing B of a mouse. For simplicity, only a portion of PCB A and a portion of housing B are shown. In operation, the mouse moves across an external surface. Semiconductor laser C is attached to a separate PCB D, with flexible connector(s) E electrically connecting laser C to main PCB A. Separate PCB D is then positioned into the desired angle (I) relative to main PCB A with additional mounting hardware (not shown). Laser C emits a beam through opening F in main PCB A and through an opening G in housing B. That beam reflects from the external surface, re-enters opening G, and strikes an array of imaging (or other photosensitive) elements in sensor H. For simplicity, lenses and other optics in the path of the beam are not shown.
Configurations such as those shown in FIG. 1 have several disadvantages. For example, additional components are needed to mechanically and electrically attach the emitter to the main PCB. Moreover, correctly positioning those components increases assembly time. Ultimately, the added components and increased assembly time raise the overall cost of the mouse. The amount by which overall cost is increased can be significant, particularly for products which are manufactured in large quantities.