Method and device for driving a matrix type liquid crystal display element

#The present invention relates to a method and device for driving a matrix type liquid crystal display element.

#For a method for scanning the matrix type liquid crystal display element, there have been known a one point-at-a time method in which each intersection of columns and rows of the matrix is scanned in succession and a one line-at-a time method in which all intersections on either one line of the columns and rows in the matrix are simultaneously driven while each line is scanned in succession.

#In a display system of the liquid crystal element, there are know transmissive type and reflective type systems. In the transmissive type system, the liquid crystal exhibits light transmissive nature upon the non-application of a certain voltage thereto but exhibits light scattering nature to become turbid upon the application of the certain voltage V.sub.0 (hereinafter defined as a selected voltage) thereto. In this specification, the row and column of the matrix are defined as X and Y lines respectively, dots at the intersections of the selected X and Y lines are defined as selected dots, dots other than the selected dots on the selected X and Y lines are defined as half-selected dots, and dots on non-selected X and Y lines are defined as non-selected dots.

#The above and other objects and features of the present invention will be understood when reading the following detailed description in conjunction of the accompanying drawings, in which:

#FIG. 1 is a circuit diagram showing one embodiment of the present invention;

#FIG. 2 is a particular circuit diagram showing one portion of FIG. 1;

#FIG. 1 shows one embodiment of a circuit arrangement according to the present invention. In the figure, an 8 .times. 8 matrix liquid crystal element 1 comprises two glass plates on one of which transparent conductive films 2 such as Nesa (a trade name) are latterally arranged and on the other of which they are longitudinally arranged. The two glass plates are superimposed on each other with an insulating spacer disposed therebetween which is made, for example, of melted glass several microns to several tens microns thick. A usual nematic liquid crystal material is filled in a gap between the two glass plates.

#In such an arrangement, matrix electrodes are formed on the upper and lower glass plates of the Nesa films 2, the intersections of which operate as image dots. These dots exhibit a transmissive nature upon the application of a low voltage thereto and become opaque upon the application of a voltage exceeding a certain level, that is, a threshold voltage. The voltage which renders the dot opaque is of the order of as much as 20 volts but depending upon the liquid crystal material. Such a liquid crystal display element serves as a character displaying device in copperation with a character generating circuit 14 as shown in FIG. 1.

#An X line driving switch unit 3 selects outputs A and B from voltage generating circuits 7 and 8 in response to outputs 40 from an x line selecting circuit 4 and generates outputs on X lines 30. A Y line driving switch unit 5 selects outputs A and B generated through inverters 9 and 10 in response to outputs 60 from a Y line selecting circuit 6, and generates outputs on Y lines 50. The Y line selecting circuit 6, on the other hand, selects signals appearing on the Y lines due to selection in response to a character signal from a character generating circuit 14 in the case where the liquid crystal display element is constructed as a character displaying device.