In recent years, various types of
portable battery powered electronic devices such as
calculators,
cell phones,
personal digital assistants, which are sufficiently small and lightweight to be readily accommodated within the user's pocket. Such devices generally employ a
liquid crystal display, together with low-consumption circuit elements, and so have a long
battery life. There are many demands on a miniaturized portable liquid crystal television receiver having a small power consumption, small thickness, and high performance. Portable television receivers allow viewing of the image or picture while traveling in an automobile, boat or other conveyance. A portable television receiver with a liquid crystal panel comprises an
antenna, receiving circuit block, and liquid crystal panel driving circuit block. The receiving circuit block comprises a
printed circuit board or ceramic board on which various independent elements or components, including an electronic tuner in a metallic shielding case, and
integrated circuits for intermediate-frequency, video signals and audio signals are mounted. A video signal amplified by a
video amplifier is converted into a digital signal by an A/D converter, and the digital signal drives the liquid crystal panel. The liquid crystal panel driving circuit composes liquid crystal driving waveforms from the video signal for driving the liquid crystal panel to develop half tone images.
