LAMP SIGNAL GENERATING METHOD, LAMP SIGNAL GENERATOR, LIQUID CRYSTAL DRIVING DEVICE AND LIQUID CRYSTAL DISPLAY DEVICE

摘要

PURPOSE: To eliminate unnecessary radiation by generating a lamp signal whose amplitude is changed according to a count value by performing a switch so as to increase the changed mount of the amplitude for the count value when a count-down is performed in an amplitude amount conversion process. CONSTITUTION: When the frequency of a clock count signal is made 7.5MHz, for instance, in a lamp signal generator 7, the count time for 128 clock count signals when a count-up is performed is 17μs. The time for 32 clock count signals when a count-down is performed is 4μs and the discharging time of a liquid crystal driving device 5 becomes the time which is the quarter of charging time or below. In the generator 7, the frequency of the clock signal to be supplied to an UP/DOWN count when the count-down is performed is made the same low frequency as the one at the time of up count. Therefore, the generator is inexpensively formed by a normal semiconductor process with a few processes. Unnecessary radiation is not generated and the image quality of a liquid crystal display device is made high image quality.