JPS63252395A - Hot cathode type discharge lamp lighter - 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] Industrial applications The present invention relates to a hot cathode discharge lamp lighting device.

Background Art For example, in a facsimile machine that is equipped with an optical reader that illuminates the surface of a document and reads the reflected light, a hot cathode discharge lamp (hereinafter referred to as a discharge lamp) is used as a light source that illuminates the surface of the document. It is being This is a method in which a fluorescent material sprinkled on the inner wall of a tube is irradiated with strong ultraviolet rays generated during discharge to emit visible light of a certain wavelength. It's no different from regular fluorescent lights.

However, if the discharge lamp used as the light source for the reading means is lit by a commercial AC power source like a general fluorescent lamp, the flickering caused by the commercial frequency (50 or 60 Hz) is not suitable for high-speed reading. 20!] High frequency lighting using Z) is being carried out. According to high-frequency lighting, the blinking per unit time reaches 40,000 times per second at 20 KHz, for example, and due to the afterglow property of the fluorescent material, a high-quality light source without flickering can be used.

FIG. 3 is a circuit diagram illustrating a typical prior art. The discharge lamp lighting device W11 rectifies the '11'a input from the commercial power supply AC by the rectifier 12, and the inverter 13 is operated by the DC output DC, and the lines / 1 , /
Output the high frequency voltage ■f to the second opening, and by this, first,
First capacitor 14 - filament f1 of discharge lamp FL
- Second capacitor 15 - filament) [2] A current If determined by the combined impedance of the series circuit formed by the capacitor 15 flows and the filaments r1 and f2 are heated. At this time, the terminal voltage Vt between both filaments [1 and f2 of the discharge lamp FL is the voltage drop in the capacitor 14 due to the above current If from the output voltage Vf of the inverter 13, if the voltage drop across the filaments fl and [2 is ignored. Vt=Vt-I f-Xc-(1) where Xc is the capacitive reactance of the capacitor 14.

When the filament fl and r2 are heated, the temperature rises over time and the filament is sealed inside the tube of the discharge lamp FL.
The voltage changes, and on the other hand, the ionization of the gas near the filaments ``1 and f2'' progresses, and discharge in the tube starts, and a new current path is formed by the discharge current Ie in the discharge lamp FL, as shown by the broken line, and the above-mentioned The terminal voltage Vt decreases, and the discharge lamp F
Due to the negative characteristic of L, the discharge current Ie further increases.

As a result, the internal impedance between the two filaments fl and fl becomes lower than the capacitance reactance of the capacitor 15, and the series circuit formed by the capacitor 15 becomes relatively high impedance, resulting in a filament).
The heating current If of fl and f2 stops flowing, and Vx = Vf - I e-Xc - (2) where Vx < Vt
... The discharge continues with the voltage Vx determined by (3) being the interelectrode discharge voltage of the discharge lamp FL, and the lamp FL is lit.

Problems to be solved by the invention In the discharge lamp lighting device according to the prior art,
Because the filament of a discharge lamp is heated and the discharge voltage is applied at the same time, high voltage is applied while the filament temperature is low, which may cause the filament member to be worn out, and also cause the filament to shift to an uneven discharge. Therefore, the operation becomes unstable, which is not favorable for the life of the discharge lamp.

Furthermore, equipment in which the discharge lamp is used is normally used and stopped repeatedly, such as a facsimile machine, and accordingly, the discharge lamp is also repeatedly turned on and off. This high frequency of turning on and off increasingly affects the life of the discharge lamp in prior art circuits such as those described above.

SUMMARY OF THE INVENTION An object of the present invention is to provide a discharge lamp and an α-lamp device that solve the above-mentioned problems and realize a long life of the discharge lamp with stable operation.

Means for solving m points between a switching element that is driven after a lapse of time; a first conversion means that converts the high frequency output of the inverter into a filament heating voltage of a hot cathode discharge lamp and outputs the same; and converts the high frequency output of the inverter into a discharge voltage of a cathode discharge lamp. A hot cathode discharge lamp lighting device comprising a second converting means for converting and outputting a signal, and a switching means driven by the switching element, wherein the switching means causes the first The filament heating voltage of the hot cathode discharge lamp is supplied from the first conversion means, and after the elapse of the time period, the discharge voltage of the hot cathode discharge lamp is supplied from the second conversion means. This is a cathode discharge lamp lighting device.

Operation According to the present invention, the inverter and timer circuit are operated by DC power supplied through the Pritsuno rectifier.

The timer circuit ticks a predetermined time, and the inverter supplies the filament voltage of the discharge lamp via the first conversion means within the set time, and supplies pIS2 after the elapse of the time. The discharge voltage of the discharge lamp is supplied through the conversion means. The two converting means are operated by switching means driven by a switching element that operates after the set time. As a result, the filament of the discharge lamp is sufficiently heated during the set time, and stable lighting operation is performed by applying the discharge voltage thereafter.

Embodiment FIG. 1 is a block diagram showing the electrical configuration of an embodiment of the present invention, and FIG. 2 is an electrical circuit diagram.

In FIGS. 1 and 12, mutually corresponding parts are given the same reference numerals.
This will be explained with reference to FIG.

? ! ! When the source switch S is closed, the input terminal U.

■The commercial frequency power from the AC power supply AC applied in between is full wave by the Pritsuno rectifier 2! i! DC voltage d
a is created and the line w1. It is derived during w2. By providing such a bridge rectifier 2, it is possible to connect a direct current BDC of a predetermined voltage to the input terminals U and V in addition to the alternating current fiAc. In this embodiment, there is no need to consider the polarity of + and -, and by forming a so-called AC/DC dual-use system, ease of use is achieved.

The DC voltage da energizes and operates the inverter 3 and timer circuit 4.

Inverter 3 is activated and line w3. For example, a high frequency voltage of 20KH2 is derived between w4.

Line w3. Between w4, a first converter serving as a first converting means for supplying a heating voltage for the filament of the discharge lamp FL is provided.
The primary coil L1 of the transformer T1 is connected. Also line w3. Between w4 are a primary coil L4 of a second transformer T2 as a second conversion means for supplying the discharge voltage of the discharge lamp FL, and a third lance T3 as a switching means realized by a saturable reactor or the like. A series circuit consisting of a secondary coil L7 is connected.

Within a predetermined time after turning on the power switch S, the primary film L6 of the third transformer T3 is in an open state because the transistor Q is cut off, and the impedance Z3 of its secondary coil L7 is extremely high. , therefore, the excitation current Is due to the high frequency output of the inverter 3 does not flow through the primary coil L4 of the second transformer T2 connected in series with the primary coil L4 of the first transformer T1.
1 is excited by the output of the inverter 3.

Therefore, within the above set time after turning on the switch S, the secondary coils L, 2. Due to the secondary voltages Vfl and Vr2 induced in L3, only the filaments 1 and 2 of the discharge lamp FL are heated.

The above set time is referred to as 1111tm during residual heat. Note that the coil LO wound around the first transformer T1 is a feedback winding for causing the inverter 3 to oscillate.

After turning on the power switch S, the DC voltage da changes to the timer circuit 4.
The voltage is also applied to the series circuit of resistor R1 and capacitor C1 forming the resistor R1, and the capacitor C1 is charged through the resistor R1, the base potential V[l of the switching element Q rises, and after a time determined by the time constant τ, the transistor Q conducts. Here, the time constant τ is τ=R−C, where R is the resistance value (Ω) of the resistor R1, and C is the capacitance fi of the capacitor C1.
(F), the time determined by the time constant τ is equal to the preheating time tm, and the primary coil L of the third transformer T3
The diode D connected to 6 is for preventing back electromotive force.

When the transistor Q becomes conductive, a collector current Ic flows through the path of line w1 - current limiting resistor R2 - primary coil L6 of the third transformer T3 - transistor Q - line w2, the third transformer T3 is saturated, and its secondary coil L6 becomes shortened. As a result, the impedance Z3 of the secondary coil L7 clearly drops to about several ohms, equivalently equivalent to the secondary coil L7 of the third transformer T3 being shortened, and the impedance Z3 of the secondary coil L7 up to that point is reduced to about several ohms. The series circuit of L7 becomes a circuit of only the primary coil L4 of ffk2) lance T2, and the excitation current IS from the output of the inverter 3 becomes the
Flows into the large coil L4 of transformer T2, PtIJ2)
A high frequency voltage p, which is a discharge voltage, is induced in the secondary coil L5 of the lance T2. Here, the capacitor C2 connected to the secondary coil L5 of the second transformer T2 is a current limiting capacitor. The above discharge voltage Vp is applied between the filament fl and f2 of the discharge lamp FL, and the discharge lamp FL is discharged using the filament fl and f2 as electrodes, after which the power switch S is opened and the output of the inverter 3 is cut off. Continue lighting until .

FIG. 3 is a waveform diagram showing the operation of the discharge lamp FL of this embodiment when it is turned on.

The power switch S is closed at time to in FIG. 3(1), and thereafter the discharge lamp is turned on vcI? according to the present embodiment until time tn when the power switch S is opened. ! 1 has been shown to work.

In FIG. fl3 (2), the timer circuit 4 is activated at time 0, and at a predetermined time, the transistor Q becomes conductive after the preheating time Lm has elapsed.

FIG. 3(3) shows that the filament fl of the discharge lamp FL is heated by the filament heating voltage Vfl.

FIG. 3(4) shows that the discharge voltage Vp is output at time t1 after the preheating time Lm has elapsed, and the discharge lamp FL is then turned on.

In this embodiment, a saturable reactor is used for the ff12) lance T2 that outputs the discharge voltage Vp, but in other embodiments of the present invention, a current transformer or the like may be used. .

In still another embodiment of the present invention, a relay may be used as the switching means, and a timer circuit may be used to drive the relay after m has elapsed since it is opened at the time of residual heat, and the second transformer T2 is connected to the inverter 3 at its contact point. Often, this allows the third transformer to be omitted, making it possible to form the first transformer T1 and the second transformer T2 into a transformer with the same iron core, realizing miniaturization of the device and reduction of production costs. can.

Effects As described above, according to the present invention, the filament of the discharge lamp is sufficiently heated within a predetermined set time, and stable operation is performed by applying the discharge voltage thereafter. Exhaustion is suppressed and flF life is realized. Furthermore, the configuration of the switching means allows the device to be made more compact.

Furthermore, since the discharge lamp lighting device according to the present embodiment handles frequencies in the high frequency range, the frequency-related members such as transformers and capacitors that constitute the device can be made smaller and lighter, and production costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the electrical configuration of an embodiment of the present invention, FIG. 2 is an electrical circuit diagram thereof, and FIG. 3 is a circuit diagram of a prior art.

Claims (1)

[Claims] A bridge rectifier, an inverter that converts DC power supplied through the bridge rectifier into high-frequency power and outputs it, a timer circuit, and a switching device driven by the timer circuit after a predetermined time has elapsed. a first conversion means for converting the high frequency output of the inverter into a filament heating voltage of a hot cathode discharge lamp and outputting the same; a second converting means for converting the high frequency output of the inverter into a discharge voltage of a cathode discharge lamp and outputting the same. A hot cathode discharge lamp lighting device comprising a converting means and a switching means driven by the switching element, wherein the switching means switches the first converting means to the hot cathode during the time period. A hot cathode discharge lamp lighting device, characterized in that a filament heating voltage of a hot cathode discharge lamp is supplied, and after the elapse of the time period, a discharge voltage of a hot cathode discharge lamp is supplied from a second conversion means.