OPTICAL TRANSMISSION CIRCUIT

摘要

PURPOSE:To facilitate regulating the resistance value of a resistor to be optimum by a method wherein the resistor is composed of a plurality of film resistance elements and the elements are short-circuited by a film conductor and the film conductor is suitably cut off so as to obtain the required luminance of the output light of a light source. CONSTITUTION:A resistor provided on a circuit board 1 is composed of resistance elements 6A-6D which are made of thin films or thick films formed by screen printing or trimming so as to have required resistance values and whose ends are used as electrodes and which are connected in series. A film conductor 5 which connects a fitting terminal 2A to an end terminal 7 and, moreover, is connected to the respective electrodes of the resistance elements 6A-6D in parallel is provided. The film conductor 5 is made of silver or gold paste and exposed on the surface of the circuit board 1 in order to facilitate being cut from the outside when the optimum resistance value is to be determined. The resistance value is regulated by cutting off the parts of the conductor 5 one by one so as to make the output light from a light source 3 have the required luminance while the luminance is being measured.