JPS5814492A - Constant current power source circuit for low voltage mercury lamp - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a low-pressure water-lamp driving power supply circuit that discharges a mercury lamp without using a low-pressure lamp and then automatically drives it with a constant current current to accurately keep the lamp light amount constant.

Some use a constant voltage transformer as a power supply circuit to light a low-pressure mercury lamp and stabilize the lamp scene after lighting, and also to use a constant voltage transformer as a power supply circuit to eliminate the use of glowlandes, which determines whether or not the lamp is lit. Conventionally, power supply circuits have been developed that detect and feed using photoelectric elements such as phototransistors. The light intensity stability after lighting is good (and power supply circuits equipped with the latter photoelectric elements tend to malfunction in bright environments, so it is difficult to expect good results).

These two conventional power supply circuits are illustrated in Figure 1%. l# In both figures, parts that operate the same are given the same reference numbers and 1 is a 100V AC input power supply,
sFi constant voltage transformer, 8Fi ballast, 5#i low pressure mercury lamp, 6 is a glow lamp, 6' is an automatic switching element in place of the glow runner, 7 is a photoreceptor that receives the lighting light of lamp 6 and drives the automatic switching element. These power supply circuits are photoelectric elements such as transistors, and as the operation of these power supply circuits is well known, the explanation thereof will be omitted, but each has its own drawbacks as described above.

The present invention eliminates all the drawbacks of WIlIF1 and above, and is optimal as a power supply circuit when a low-pressure mercury lamp is used as a light source for a precision gauge column. An example circuit is shown in FIG.
- is a series control transistor, OF is an error comparison arithmetic amplifier, SW+Fi switches the output from TR in a miswitching path, and outputs voltages with opposite phases to OUT, OUT, and K, respectively. E#iSW.

This is the ground terminal of the circuit. Eref is the reference voltage for the amplifier OP, on, o is the backflow prevention diode, TR,
, TR, is the red-hot current control transistor of ficimen) F, F, R1 is the discharge current detection resistor of run 7"L, R,,
RsFi This discharge current detection resistor R, K is a resistor that divides the generated voltage, cuts off TRs, and stops the filament current, cIFi Smoothing capacitor, C2
is a delay capacitor to stop the red-hot current of F and F after the discharge starts.

Initially qTRs are in the on state 111, and the diode O4,
The current for starting discharge of run fL passes through O7 and reaches filament F.
, F alternately, and the filament first becomes red hot. At this time, the output of the amplifier OP is maximum on the + side, the series control transistor TRI is in a completely conductive state, and the maximum voltage of the power supply circuit is applied to each filament to facilitate the start of discharge. When discharge starts, the discharge current passes between F and F and reaches the output terminal OUT of the switching circuit.
, from 0υT2, or from 0UT2 to 0υT1, and then passes through the E terminal of the switching circuit SW.
Flows through resistor R1.

This generates a voltage R+Kt, turning on transistor TR2 and turning off TRs.
□The current to make the components F and F red-hot is stopped, and the voltage generated by the amplifier OF and the resistors R and Ic is fed back to the series control transistor TR+ so that the voltage generated by the resistors R and Ic is equal to E'・f-. L#i appropriate: 1
That's one thing. -The place where the lighting is incomplete in the second movement! The above procedure is repeated until the light is completely lit.

As described above, the present invention has a glow lamp and a stabilizing switch, but does not have any photoelectrons for detecting lighting, and has a very simple circuit and an extremely precise power supply circuit for controlling current. Also very useful as? It is.

[Brief explanation of drawings]

Figure 72 shows conventional type 0 low pressure 7k @ 5:y f F
f4 [6@00 path, FIG. 3 is a circuit diagram of a power supply circuit showing an implementation of the present invention. T, Rbi... series control transistor, SWl...
Switching circuit, OPl... operational amplifier 1. Er
ef...OP+...Low pressure mercury lamp, F...
Runner filament, TR2, TR,...Filament current control transistor. Figure 1 Figure 2 ・

Claims (1)

[Claims] ゛The input power supply is connected to each filament of the low-pressure mercury lamp through a series control transistor and a switching circuit that outputs alternately. It is equipped with a circuit that flows a discharge current through resistance KK, detects this voltage drop, and cuts off the filament red-hot current, and an operational amplifier that inputs the voltage drop and the reference voltage and feeds back the output to the series control transistor. A low-pressure mercury lamp circulation and current power supply circuit characterized by comprising: