Draughtsman's rule with switchable LCD scale-ratio indicator - has power source supplying LCD elements along edge of rule, selected by pushbuttons

摘要

The indicator (11;41,42) is an LC indicator which can be arranged at one or both rule longitudinal edges. The indicator (11;41,42) has a seven segment indicator. The voltage source can include one or more solar cells, arranged in a row along the rule longitudinal direction. Manually operated selection keys are provided for the selection of a desired scale, and the keys may be push buttons. A control unit receiving signals concerning the resepectively selected scale and controlling the indicator, is arranged in the central region of the rule, pref. below the selection keys (17). ADVANTAGE - Can have any shape e.g. as table rule, triangular rule or drawing board component. Facilitates measuring of drawings of linear measurements also with differing scales, in simple manner.