Scale plate for measuring instruments

Claim 1

A scale plate having a plurality of scale arrangements for use with an electrical measuring instrument, the instrument having a changeover switch for selecting one of the plurality of scale arrangements and a pointer which is pivotably supported to indicate on the selected scale arrangement the electrical measurement in an analog manner, the scale plate comprising plural displaying means for selectively displaying each of the scale arrangements, each of the plural displaying means being separately disposed on a plate member, each of the displaying means having a voltage excitable material contained within a chamber formed from a transparent front electrode means spaced from a rear electrode disposed on the plate member and a continuous insulating side wall joining the transparent front electrode means and the rear electrode, the front electrode means including the scale arrangement, the scale arrangement being an arcuate scale having alphanumerics and/or numerics and/or characters designating values assigned to scale marks, whereby one of the plurality of scale arrangements can be selectively rendered visible to the exclusion of the remaining scale arrangements by applying a voltage between the front electrode means and the rear electrode of one of said plural displaying means selected in accordance with the position of the changeover switch.