FIG. 1 (Prior Art) is a stylized view of an infrared (IR) touch sensor frame assembly 1. A printed circuit board (PCB) frame body 2 has a portion of PCB material cut out of the center of the body such that the remaining PCB material forms a single-piece, four-sided frame. IR light emitting diode (LED) transmitters and receivers are disposed on the PCB frame body 2 for touch sensing. A series of X-axis IR LED transmitters 3 are arranged on one side of the PCB frame body 2 opposite a matching series of X-axis IR LED receivers 6. A series of Y-axis IR LED transmitters 4 are arranged on one side of the PCB frame body 2 opposite a matching series of Y-axis IR LED receivers 5. The IR LED transmitters and receivers are electrically connected through the PCB frame body 2 to a controller (not shown). A screen typically fits in the cut-out center of the PCB frame body.
Signals from the IR LED transmitters and receivers disposed along sides of the IR touch sensor assembly are utilized by a controller to determine the location where a user touches the screen. In FIG. 2 (Prior Art) touch event 7 represents the user's finger or pen stylus as it is pressed against the display at a particular location. The object creating the touch event 7 is typically a pen stylus or a finger pressed on the framed screen. In one example of a touch event 7, the object causing the event blocks the beam of infrared light from one of the series of IR LED transmitters disposed along the X-axis 3 from being received by the associated X-axis IR receiver 9. Based on the signals from the X-axis IR transmitters and receivers, the controller determines the X-axis position of the touch object 7. And, the object 7 blocks the beam of infrared light from one of the series of IR LED transmitters for the Y-axis 4 from being received by the associated Y-axis IR receiver 8. Based on the signals from the Y-axis IR transmitters and receivers, the controller determines the Y-axis position of the touch object 7. Thus, the position of the user's touch on the associated screen is determined by a controller.
FIG. 3 (Prior Art) is a view of the top side of a typical one-piece IR touch sensor frame assembly 10. Corner section 11 connects bottom and side edges of the IR touch sensor frame assembly 10 such that there are no breaks in the PCB frame material. Corner section 11 has a beveled elbow cut-out for fitting into a casing.
FIG. 4 (Prior Art) is an exploded view 11 of the corner section 11 of the assembly of FIG. 3. Assembly 10 is a one-piece printed circuit board 14. A Y-axis IR receiver 13 is shown as it is disposed on one side of one-piece printed circuit board 14. Y-axis IR receiver 13 is electrically connected through the printed circuit board 14 such that electrical signals are transmitted from Y-axis IR receiver 13, through the printed circuit board 14 and to a controller for processing the signals.
Formation of an IR touch sensor frame from one piece of PCB material has several drawbacks. The center cut-out portion of PCB must be discarded, resulting in expensive waste of PCB material. Due to the rectangular shape and unused center space, storing and shipping of such assemblies is inefficient. Furthermore, if a component (such as a receiver or transmitter) is damaged, the entire assembly must be discarded. A method of assembling PCB frame sections such that they can be mechanically and electrically coupled at their corners is desired.