Method and apparatus for driving electrochromic display device

In an electronic timepiece having a power source, an oscillator circuit, a frequency divider coupled to the oscillator circuit, counter means coupled to an output of the frequency divider to generate clock pulse information signals, decoder means for converting the time information signals into display information signals, and an electrochromic display device having a plurality of display elements, the improvement comprising:

• a latch circuit, having data and clock input terminals and Q and Q output terminals, said data input terminal is coupled to an output of said decoder means and said clock input terminal coupled to the frequency divider to receive a clock pulse therefrom, said latch circuit for storing display information signals delivered from the decoder means and generating output signals delayed for a time interval from the display information signals;
• a NAND gate, having two inputs, one input coupled through an inverter to the output of said decoder means, for generating a first output pulse, in response to a falling edge of each display information signal having a pulse width;
• an AND gate, having two inputs, one input coupled to said Q output of the latch circuit and the other input coupled to the output of said decoder means, for generating a second output pulse, in response to a rising edge of each display information signal having a pulse width;
• a P-channel MOSFET responsive to the first output pulse to cause the flow of electric current through said display element in a bleaching direction;
• and
• an N-channel MOSFET responsive to the second output pulse to cause the flow of electric current through said display element in a coloring direction.