Hot Cathode Fluorescent Lamps with Auxiliary Plate (II)

Abstract

The test of hot cathode fluorescent lamps with auxiliary plates have been carried on at the State Osaka Railway Bureau since April in 1953.In this paper we are to report the results of the fundamental measurements of these lamps.The operating circuit for these lamps is shown in Fig. 1. The property of our lamps differs from that of commercial lamps in several points as will be stated below.1. Usually commercial lamps have the directly heated filament type cathode. Our lamps, however, have not only the same catode as that of commercial lamps but the indirectly heated filament type cathode Fs and F (Fig 1). The operating life of these lamps is very long.2. Electro-magnetic type relay was used in order to start these lamps. When starting, the auxiliary discharge current between the auxiliary plate G and the directly heated filament type cathode Df...(G and Df are both at the positive side of d. c. source)...is the working current of the relay. Once it was started, main are current becomes the working current.3. R1 and R2 are the auxiliary resistances which were used in order to give the potential difference between G and Df. M1 and M2 are the coil of the relay and P is the contact. In this device even if the source voltages drop to 75V, our lamps can easily start. Starting time is abott 0.5-1sec.4. L1 and L2 are the choke coils which are used to give the transient high voltages to the lamp for starting. These two coils are set at each side power source, and thus we can minimize the bulk of the choke coil because the choke coil that is connected to negative side of d. c. source contributes mainly to the starting of the lamp. In this circuit, the polarity of the power sourceis changed by a change-over switch.5. We succeeded to delay the time when the so-called dark-end effect is observed, by using this indirectly heated filament type cathode. At the temperature up to 0°C, we did not find this effect for about 50 hours. Further practical tests for these lamps are now going on well in our laboratory.