Abstract: A protective mechanism terminates the emission of a laser beam from an inadvertently inverted laser input device. A transmitting/detecting circuit is positioned under a laser input device that emits laser beams from a laser light. The transmitting/detecting circuit projects an infrared ray to a working surface to be reflected therefrom, with the reflected infrared ray detected by the transmitting/detecting circuit. The laser light is turned off if the transmitting/detecting circuit fails to detect the reflected infrared ray.

Abstract: A protective mechanism terminates the emission of a laser beam from an inadvertently inverted laser input device. A transmitting/detecting circuit is positioned under a laser input device that emits laser beams from a laser light. The transmitting/detecting circuit projects an infrared ray to a working surface to be reflected therefrom, with the reflected infrared ray detected by the transmitting/detecting circuit. The laser light is turned off if the transmitting/detecting circuit fails to detect the reflected infrared ray.

Abstract: An optical input device has a light source for emitting a light beam over a working surface that generates a reflected light beam. The input device further includes an optical sensing module that detects the reflected light beam from the working surface, and which stores a coefficient. The input device also has a control unit coupled to the optical sensing module for reading the coefficient and outputting a feedback signal based on the coefficient, and a current controller coupled to the control unit for receiving the feedback signal and, based thereon, modulating the light beam generated by the light source.

Abstract: A presentation system has a computer, and a projector connected to the computer to receive image information from the computer, and to project one or more images on to the background. The system also includes a pointing unit having a light module that emits a light directed at the background, an image-capturing device that captures the one or more images projected on to the background, with the captured images including the original images together with the light from the pointing unit. The system further includes an image-capturing device connected to the computer to provide thereto information regarding the captured image, and a processor for controlling cursor movement based on the captured images received from the image-capturing device.

Abstract: A measuring device to measure the surface level of liquids comprises a pair of probes each having a conductive body and an isolated coating layer enclosing the conductive body in such a manner that onlya little portion of the body is exposed outside of the coating layer; and a measuring circuit connected to the pair of the probes. The measuring circuit is provided with a power source, an amplifier circuit and an alarm device. When the surface level of the liquid passes through the exposed portion of the body of the probes during measuring, the change of the electrical property between the pair of the probes will be magnified to actuate the alarm device.