Display indicator showing switching matrix operational state - has interchangeable foil designation mask over indicator display matrix

摘要

The equipment indicates the switch state of connections in a switchblock, partic. in a telephone exchange. The indicator is a flat-faced matrix display unit with interchangeable marking facility so that the sign-writing applicable to the several indicators in the matrix may be changed according to the location and application of the equipment. An easily interchangeable light, transparent foil, is laid or slid over the indicator matrix (AF), and held by the frame of the device, so that each indicator element (AE) corresponds to a marking on the foil and, by choice of colours, provides a high contrast display when the indicator is lit. The frame of the indicator provides electrical insulation and support.