| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve a problem that a sensor-incorporating liquid crystal display device, which has an optical sensor for detecting brightness of an ambient environment, and an ultrasonic sensor for detecting an approach of a human being, needs to have a circuit for detecting two kinds of sensors, becomes expensive since the ultrasonic sensor or an infrared sensor needs a dispatching circuit leading to a high cost, and consumes large standby power for transmitting the ultrasonic wave or infrared ray. <P>SOLUTION: The liquid crystal display device is used for display of characters and graphics. Optical sensors of the same kind are disposed on an upper part and a lower part of a housing at a display surface side of the liquid crystal display device. When a user approaches the liquid crystal display device, temporal changes in dark and bright detected by the upper optical sensor and lower optical sensor are periodically measured, and the measured values are stored in a storage unit arranged in a control unit. The measured values are compared with a threshold stored in the storage unit of the control unit in advance, and if the measured values exceed the threshold, the power of the liquid crystal display device is turned on. <P>COPYRIGHT: (C)2013,JPO&INPIT |
