A method for manufacturing an electron source includes the steps of covering a substrate provided with a first electrode and a second electrode by a container, introducing a gas composed of a carbon compound into the container, and forming a carbon film by applying a voltage between the first electrode and the second electrode. Between a main bus 1 and a main bus 2 disposed in parallel, a circuit breaker 3, a circuit breaker 4, and a circuit breaker 5 are disposed as being aligned so that each axis line is orthogonal to a direction of axis lines of the main buses 1 and 2. The amplifier has an input operatively coupled to an inputoutput pad of an integrated circuit chip. The image display device is swivel-mounted on the instrument housing around a vertical axis extending perpendicularly to the longitudinal symmetrical axis of the manual instrument.