Citizen Watch Company, Ltd.

Hiro Fujita

Akira Tsuzuki

Shigeru Morokawa

Fukuo Sekiya

Seigo Togashi

Heihachiro Ebiha

A method of cyclically driving an electro-optical display device having a matrix array of a plurality of row electrodes and a plurality of column electrodes, wherein said column electrodes intersect with said row electrodes to provide a plurality of display elements at intersections between said row and column electrodes, comprising the steps of: applying row drive signals to said row electrodes, respectively; and applying one of first, second and third column drive signals to each of said column electrodes, with said first column drive signal inducing a non-display state at all of the display elements along each column electrode, said second column drive signal inducing a non-display state at a single display element along said each column electrode and inducing a display state at the other two display elements along said each column electrode, and said third column drive signal inducing a display state at all of the display elements along said each column electrode; wherein each of said row drive signals takes a plurality of voltage potentials during a half cycle period divided into prescribed time intervals and one of said row drive signals takes one of said voltage potentials different from those of the other of said row drive signals during each of said prescribed time intervals; and wherein said first column drive signal takes a reference voltage potential equal to the mean value of said voltage potentials of said row drive signals during said prescribed time intervals of said half cycle period, said second column drive signal takes a first voltage potential different from those of said row drive signals during one of said prescribed time interval, said reference voltage potential during another one of said prescribed time intervals, and a second voltage potential different from those of said row drive signals during another one of said prescribed time intervals, and said third column drive signal takes the first and second voltage potentials during each of said prescribed time intervals.

Matrix driving method for electro-optical display device

In a multi-layer display device such as a liquid crystal display, each of a plurality of sets of display elements is defined by a corresponding common electrode and a plurality of segment electrodes. Segment electrodes of sets of display elements which will not be activated simultaneously are connected together, with at least one of these sets being maintained in a deactivated state by means of a special drive signal applied to the corresponding common electrode. The level of time-sharing which must be utilized for driving the various common electrodes, for a given number of external connections to the segment electrodes, can thereby be reduced, or the overall number of connections made to the display device can be substantially reduced.

Multi-layer display device with nonactive display element groups

In an electronic timepiece, a system for producing a unit time signal with a high degree of frequency stability, composed of a low frequency oscillator, a high frequency oscillator of a high degree of frequency stability which is activated only during periodic short intervals, and means for producing a timebase signal which is an exact integral submultiple in frequency of the high frequency oscillator signal, by modifying the output signal from the low frequency oscillator on the basis of periodically recurring phase coincidence between the high and low frequency oscillator signals. Information on this phase variation is stored in digital form, and is utilized to correct the low frequency signal during periods when the high frequency oscillator is inactivated.

Unit time producing system

A system for performing frequency division of a high frequency signal by intermittent operation of a frequency dividing counter circuit and by a phase lock loop circuit, in which phase lock is periodically achieved with an output of the counter circuit. Phase lock loop circuit is of novel design which provides exact phase lock without cyclic variations from the reference phase.

Frequency division system

An electronic timepiece having a high frequency oscillator with a high level of frequency stability and an electronically controlled low frequency oscillator. The phase of a high frequency signal from the high frequency oscillator is compared with a signal from the low frequency oscillator, and a digital signal is produced in accordance with the phase difference. The digital signal alternately controls the frequency of the low frequency signal to be slightly greater than an exact submultiple of that of the high frequency signal and slightly less that an exact submultiple of the high frequency signal, so that with respect to a relatively long time interval the frequency of the low frequency signal is an exact submultiple of that of the high frequency signal, the low frequency signal being thereby utilizable as a timebase signal for the timepiece.

Electronic timepiece oscillator circuit

A frequency standard for an electronic timepiece comprising a low frequency oscillator and a high frequency oscillator of which the frequency is an integral multiple of a predetermined frequency of the lower frequency oscillator. A phase difference detector is coupled to the lower and higher frequency oscillators to produce a signal occurring at intervals depending on the phase difference between the two oscillators. A frequency divider is provided to divide down the frequency of the signal by the integral multiple to produce a phase difference signal. The phase difference signal is algebraically added to the lower frequency oscillator signal to generate an output signal of which frequency is equal to that of the high or frequency oscillation signal divided by the integral multiple.

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Tokorozawa, Japan

Hiro Fujita