JPS634597A - 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 [Technical Field] The present invention relates to a discharge lamp lighting device that lights a discharge lamp using the high frequency output of a transistor inverter circuit.

[Background Art] Fig. 2 is a diagram showing the circuit diagram of a conventional high-frequency discharge lamp lighting device. Diodes D1, with the polarities shown for transistors Q, , Q2.
D2 are connected in parallel.

However, the diodes D, ,D are not necessarily required.

a resonant circuit A including a capacitor C7, a capacitor C2, a choke L1 and a discharge lamp a in parallel with the transistor Q1;
A series circuit of 8 primary rice grains nl of the drive transformer T is connected. With such a configuration, a series inverter circuit or a bar 7-shaped inverter circuit is constructed. -Omaki#! n! The drive transformer T1 has secondary windings n2, n
, and the secondary winding 111++13 is a transistor Q,
, Q2's control resistance R+, and R2's Ra. Furthermore, a starting circuit for the inverter circuit is provided. This startup circuit consists of a resistor R1 and a capacitor C3 connected in series, and a resistor R1.
It uses a bidirectional tri-element, such as a diac Q, whose one end is connected to the connection point of the capacitor C0 and the diac Q3, and the other end is connected to the base terminal, which is the control terminal of the transistor Q2. There is. Further, the connection point between the resistor R3 and the capacitor C1 is connected to the anode of the diode D3, and the cathode is connected to the collector of the transistor Q2.

The operation of the circuit described above is as follows. That is, when the power switch SW is turned on, the capacitor C0 is charged via the resistor R3. Then, when the voltage on capacitor C1 reaches the breakover voltage of diac Q, capacitor C1 discharges through the base-emitter junction of transistor Q2. This discharge causes transistor Q2 to conduct for the first time. Therefore, a current flows through DC current [E→capacitor C5→resonant circuit A→primary -84tin of drive transformer T1,→transistor Q2→DC power supply E, and charges capacitor C1. This current flows through the primary 8 paddy nl of the drive transformer T1, and therefore the secondary windings n2.1.1 of the drive transformer T. A voltage is induced in The induced voltage in the secondary winding n has a polarity (w1 voltage) that maintains the conduction state of the transistor Q2. After that, the current increases in an attempt to charge the capacitor C1, but as the charging progresses, the current gradually decreases, and when it approaches zero, the feedback voltage from the drive transformer T is applied to the forward voltage of the transistor Q1.
A reverse voltage is applied to transistor Q2, and transistor Q2
is turned off, and transistor Q1 is turned on. Then, a closed circuit is formed between capacitor C1, resonant circuit A1, the large winding of drive transformer T1, and transistor Q1, and capacitor C1
begins to discharge. The vibration caused by the discharge of capacitor CI then turns off transistor Q1 and turns on transistor Q2. and capacitor C2
A voltage of 1 is applied to the discharge lamp e to turn on the discharge lamp C. However, if we consider the lifespan of discharge lamp a, then discharge lamp e will start! It is necessary to preheat the filament of the discharge lamp α before applying the M voltage. This configuration is shown in FIG. A series circuit of a mechanical or semiconductor switch S1 such as a relay or a tri-after and a current transformer T2 is connected to a discharge lamp 2.
are connected to the non-power supply side terminals of filaments f, , f2. When the power is turned on, switch S1 closes and the filament r
1, f2 and current transformers T2, T to obtain a desired current by superimposing current wires 2 and 3. After about 1 second, the timer T opens the switch S1 to light the discharge lamp α. In this way, before turning on the power and lighting the discharge lamp, one filament current is passed through the filament for a predetermined period, and the filament C is
After heating the lamps 1 and 2, the discharge lamp e is turned on so as not to impair the life of the discharge lamp e. However, in the conventional preheating method, a separate current transformer T
2, T, was required, making the configuration complicated.

There is also a conventional example as shown in FIG. This conventional example uses a constant current push-pull inverter driven by voltage feedback from the oscillation transformer OT.
Output 8 wires 11.T with preheating compensation winding n+゛. It is wrapped so that the polarity is different (or the same) as that of ゛. In this conventional example, the preheating compensation winding #i n 4 ' is a winding for which the output voltage is applied. In general, when a commercial power supply is used and a discharge lamp T is started and lit, the starting voltage or α lamp maintenance voltage is high, and the oscillation transformer OT is a step-up type, and there are many output windings and I windings. is normal. Therefore, the preheating compensation winding n, +
If the number of turns is to be set to the optimum preheating current value by maximizing the effect of depolarization (addition), it will inevitably be necessary to have an output of 8 wires and a large number of turns in proportion to the number of turns. As a result, the oscillating transformer O
Due to the space constraints of the winding bobbin of T, it is not possible to wind the required number of wire diameter turns, resulting in power loss and heat generation.
An inconvenience was observed in f. Also, preheating compensation winding +1. There are problems in that the number of 8's increases, the core size increases, and the cost increases due to increased space.

In view of this problem, a discharge lamp lighting device using a current feedback drive inverter circuit has been proposed, in which a predetermined preheating current can be obtained at a desired frequency.

FIG. 5 shows the circuit, in which the primary winding n41 of the current transformer T is inserted between the non-power terminals of the filaments f1 and f2 of the discharge lamp t via a preheating switch S1, The secondary windings n4□ and n43, which are windings for frequency correction of the current transformer T4, are driven by the transformer T1.
It is connected in series with the secondary winding n2, n of the. The other configurations are similar to those shown in FIG. 2. In this circuit, first, during preheating when the preheating switch S is on, the DC power supply E → power switch SW → capacitor C1 → one filament f1 of discharge lamp e → current transformer T
Volume 4 n4. A filament current flows through the switch S1, the other filament r2 of the discharge lamp C, the choke L, the large winding n of the drive transformer T1, and the transistor Q2.

Here, the current flowing through 7S#i n of the drive transformer T is In+, and the current flowing through windings n2 and n3 is In2, I
nz, volume Mn, , n2, n3s n4+s 114
2. The number of turns of n43 is N5, N2, N5, N 41s respectively.
N12, N43, and when the switch S1 is turned on, the voltage of the current transformer T, Sin, and both filament voltages of the discharge lamp T are small, so the current flowing through the capacitor C2 is small, and the current In is small. Suppose that the current is flowing through the switch S winding M n , . It is assumed that the capacitor C2 is substantially short-circuited by the switch S1.

In this case, the current in2° determined by the base current of transistors Q1 and Q2 = (N1/N2) ・・In+, inz'=
N1/Nz ” Inl, current In, and number of turns N 41
, N4□ and the current i determined by the turns ratio of N43 (N41/N42) ” In+,
:n43"N417H4)" Synthesis (superimposition) with In+
61 is made and supplied. Note that the capacitor C2 is substantially short-circuited by the preheating switch SI.

In other words, the current In2, In) is I r+2= in'z+ in', 2, I n3=
This holds true based on the relationship: in') + in'ni.

Here, in'B is newly added to the current source of in'2.1n゛3.
4 ins are added to each, and constitute the base drive power supply of transistors Q1 and Q2. At this time, transistor Q
,, The equivalent circuit of the base emitter of Q2 is represented by a diode, and the forward voltage drop of this diode is expressed as Vp and V
If p is 2, this value shows almost constant voltage characteristics, so
Current source in'42,! When l+'43 is newly added, the voltages v1 and v2 of the load seen from the current source group increase, but the voltages vF and VF2 hardly change and become close to - constant, but the transistors Q, Q2 base bias voltage v
1, v2 is the VOI when there is no current transformer T,
The voltage value is higher than vo2, and the voltage value is higher than Vp 2, vp z-
1m) The voltage applied to the base emitters of the transistors Q, . In reality, the preheating current increases even more because a positive feedback voltage is applied by the drive transformer T1 and the current transformer T, and the effect on the setting of the preheating current value of the current transformer T4 is large. Flywheel current ID1% flowing through diodes D1 and D2 TD2 and flywheel current waveforms of transistors Q1 and Q2. The collector electrician told me to think about it in conjunction with 1% IQ2. 2 is the base bias time, which increases as 2 becomes longer, and as a result, the energy of the chip L1 also increases, and the flywheel currents ID+ and I flowing through the diodes D1 and D2 increase.
DZ is also large, and the discharge (conduction for diode DI and D2) time is longer when o vol (VO2).

to t4 when vl (v2).

According to the above, if there is no current transformer T4,
The period is +tI)×2, but by using the current transformer T4, the period becomes approximately (t4+tz)×2, which becomes longer and the oscillation frequency becomes lower.

Due to the preheating state in which the preheating switch Sl is turned on, the winding of the drive transformer T1 is determined by the natural vibration frequency f0° of the circuit, which is determined by the component constants of the capacitor C2, the filament f1 of the discharge lamp, the resistance r2, and the choke L. n1 and n2,
n, and 6 wires n4 and n42 of current transformer T4,
When the switching frequency of the transistor QC2 determined by n43 is set to be high, the current flowing through the capacitor C1, the winding n, the preheating switch S1, and the choke L winding #an becomes a slow phase current. . These are capacitors C1, C2, filament resistance of discharge lamp a, and
This is because the combined impedance becomes inductive. Since this composite impedance element is inductive,
As the oscillation frequency decreases, the current flowing through the composite impedance element increases. The toe preheating current increases,
It can be seen that the desired optimum current value can be set. Therefore, the filament current can be set arbitrarily large.

The operating frequency when the preheating switch S1 is turned on can be arbitrarily set by the winding M value of the current transformer T4, and the preheating current can be determined to approximately a predetermined value. When the switch S1 is turned off, no current flows through the winding n41 of the current transformer T, so the current transformer T4 no longer functions as a current source, and the impedance values of the winding ports 2 and 43 are Since it is almost negligible and can be ignored, it can be set to a predetermined lamp current.

When the composite impedance element including the capacitors C1 and C2, the resistances of the filaments r1 and f2, and the choke L1 is set to have a capacitance of -2, the impedance is reversed to the case of the inductive impedance described above.

For a given lamp current value under conditions (e.g. inductive, capacitive, etc.) determined by the main circuit of capacitor C1102, discharge lamp 2, and choke L1, oscillation occurs during filament preheating regardless of the lamp current. By changing the frequency and increasing or decreasing the preheating current, an arbitrary preheating current can be set, and the life of the discharge lamp α can be improved, and the design becomes easy. Also, while the light is on, the preheating switch S turns on the current transformer T.

Since the winding n41 is separated from the circuit, it does not affect anything else. Furthermore, capacitor C is connected while the light is on! , C2, each discharge lamp, choke L1, winding #'1nlSn2,n), and will flow a predetermined lamp current.

As described above, the circuit of FIG. 5 can solve the problems of the conventional circuits of 2nd to 4th circuits.

Figure f56 shows a lighting device with two lamps in series, which is a development of the idea of the circuit in Figure 5.This circuit example connects a 100cm commercial power supply AC to a capacitor CF through a power switch SW.
A diode D is connected through an input noise prevention filter consisting of a choke TF and a resistor for preventing inrush current flowing to capacitors Cs+, C82, etc. that constitute the voltage doubler power supply circuit.
280■ for s+, Ds2, capacitor CS l, Cs2
It uses a DC power source that has been voltage-doubled and rectified, and the capacitor C2 has two fluorescent lamps connected in series.

Now, discharge lamp 2. filaments r1, r2, discharge lamp a2
In the circuit for preheating filaments fs, f, a current transformer T is used to preheat filaments f2 and f3. That is, the primary windings +1 and 1 of the current transformer T are connected between the non-power terminals of filaments f1 and r4 via a preheating switch S, and the secondary windings +1 and 2 are connected to the filament terminals fz and r, respectively. Further, another secondary winding n33 is connected in series to the secondary winding n2 of the drive transformer T1 as a winding for frequency correction. Here, the preheating current of the filament (fz, f) is set by the turn ratio of 8 wires n, 1 and n3, and is usually configured at 1:1.

Then, in order to set the preheating frequency to an optimum value, the conduction period of both or one of the transistors Q1 and C2 during preheating is changed. Here, the operation of the current transformer T of the fjS5 circuit can be easily and reliably performed by adding several turns (n, . . . ) to the primary side of the current transformer T of the circuit of this embodiment.

By the way, when the circuit in Figure 6 is normal, Figure 7 (a)
As shown in (c), the collector-emitter voltages cε of the transistors Q, , Q2 become the power supply voltage E when they are off, and the bases have currents I n2 . r n3 flows.

By the way, when the discharge lamp e or the discharge lamp 2 is removed, if the E or H portion is momentarily opened, lamp current flows through the secondary winding n12 of the current transformer T. This current is In3
2, a voltage of L"dlnsz/dt is induced in the secondary winding 1n32 in the direction of the arrow. However, L" is the voltage of the winding n3.
The inductance value of 2 is shown. Secondary winding n.

are wound with the same polarity, so if the number of turns of the secondary winding #X n s 2 is n2° and the number of turns of the secondary winding n33 is n, ゛, then (nv''/n2') ・L' ・( d I
A current of n:+z/dt) is induced in the winding #in3:l. The current flowing through the secondary winding RnL3 at this time is In3.

During normal lighting, the lamp current is capacitor C3t → capacitor C3 → E → H → discharge lamp α2 → Chitsuk L, → winding Jin+ of drive transformer T1 → oscillation transistor Q2 →
When flowing with the capacitor C32, the winding M of the drive transformer T
Since a reverse bias is applied to n2, the transistor Q1 is off, and a forward bias is applied to the winding n1, so the transistor Q2 is on. This is the section indicated by X in FIG. At this time, as mentioned above, when the discharge lamp is removed, the hole is opened or the hole is opened, and the lamp current flows to the secondary winding n3□ of the current transformer T.
The current 1n33 induced in the secondary winding #1n3s attempts to turn on the transistor Q1 via the feedback winding Rn2 to the drive transformer T and the base resistor R. At this time, transistor Q1 is off and the collector
A power supply voltage E is applied to the emitter as Vcε, and the negative transistor Q2 is in an on state as shown in FIG. 8(d). Therefore, while the power supply voltage E remains applied to the transistor Q1 for a moment, a current In23 flows through the base and becomes conductive, causing a short circuit. As shown in FIG. 8(c), the collector current IC1 flows through the trannostar Q→transistor Q2), exceeding the ASO region of the transistor Q and destroying the transistor Q. be. Here, the power supply voltage E is the charging voltage of the capacitor Cs+ and the capacitor Cs2.

In addition, when the lamp current flows in the direction of capacitor C3 → transistor Q1 → drive transformer T, winding IIAn1 → chijik L → discharge lamp t2 → Heho → discharge lamp Q+ → capacitor C2, contrary to the above, transistor Q1 is turned on. At this time, In33 having a polarity opposite to that described above flows to the base of the transistor Q, and attempts to turn off the transistor Q1, but at this time, no voltage is applied to the transistor Q, and there is no problem in the ASOfii area. Figure 8(e) shows the current In3 flowing to the base of transistor Q2, and Figure 8(f)
is a transistor [Object of the Invention] The present invention has been made in view of the above-mentioned problems, and its purpose is to prevent the secondary @ of the current transformer, Mll: current from flowing when the discharge lamp is removed or on the circuit. An object of the present invention is to provide a discharge lamp lighting device that can prevent a switching element from being destroyed by preventing a voltage from being induced in a frequency correction winding.

[Disclosure of the Invention 1] The present invention comprises a switching element for oscillation, a current-limiting immunity element connected to the power supply side end of a filament of a discharge lamp, a primary winding for causing a current to flow through the immunity element or the discharge lamp, and a primary winding of the switching element. At least an inverter circuit is configured with a drive transformer having a secondary winding connected to a control terminal to drive the switching element, and two connected in series at the high frequency output of the inverter circuit.
In a discharge lamp lighting device for lighting a discharge lamp, one end of the lamp defines a series circuit between the primary winding of the current transformer and a switch element that is turned on for a predetermined period of time after the power is turned on, and turned off after a predetermined period of time. #C is connected between the non-power supply side other end of the filament connected to the power supply side, and the frequency correction winding of the current transformer that constitutes a current source that is a determining factor of the oscillation frequency of the inverter circuit is connected to the switching element. and the secondary winding of the current transformer is inserted in series between the commonly connected filaments of both discharge lamps, and the secondary winding of the secondary It is characterized by connecting another impedance element in parallel to the line.

The present invention will be explained below with reference to Examples.

41 bells! Figure @1 shows the circuit configuration of this embodiment. This circuit has an impedance element Z connected in parallel to the secondary winding n32 of the current transformer T in the circuit shown in P146. This impedance element Z is for shunting the current flowing to the secondary winding gt n 32 of the current transformer T) and reducing the voltage induced in the secondary winding @ n 32. Here, if the current flowing through the secondary 8MAn 1+2t is In,2'' and the current flowing through the impedance element Z is In32', then what is the current In3□?
! It is a composite current of & current In32' and current ln=2'', and current I n,, = current I n3z' medium current I n
Therefore, by flowing more current I IN2' and less current Int□'', the voltage l'dIn32''/
dt becomes a small value. Here, the impedance value Z0 of the impedance element Z is the filament during preheating when the switching element S is on (f2. [It is desirable that the value does not affect the preheating current for preheating 3,
Also, the value must be smaller than the inductance value L' of winding #in 32. This relationship is shown in the following equation.

R< Z, <ωL (where R is the filament that is commonly connected to discharge lamp e2), the series combined resistance of L and f3, ω is 2πf1f is the oscillation frequency, and L is the secondary winding of the current transformer. @n
32 inductance values are shown.

The impedance element Z may be a resistor, a capacitor, or an inductance element as long as it satisfies the above inequality.

Therefore, in the device of the present invention, when the discharge lamps C, C2 become disconnected or other problems occur, the secondary winding M of the current transformer T,
Even if current flows through N3□, it is shunted by the impedance element Z, so the voltage generated in the secondary winding RN3□ is reduced, which reduces the voltage induced in the secondary winding N33, which is a winding for frequency correction. , transistors Q, , Q2 can be prevented from being damaged.

[Effects of the Invention] In the discharge lamp lighting device configured as described above, the present invention includes a series circuit between the primary winding of the current transformer and a switch element that is turned on for a predetermined time after power is turned on and turned off after a predetermined time elapses. One end of the lamp is connected between the other end of the 4F power supply side of the filament connected to the power supply side, and the winding for frequency correction of the current transformer constituting a current source that is a determining factor of the oscillation frequency of the inverter circuit is connected to the above. It is inserted into a feedback circuit formed by the control terminal of the switching element and the secondary winding of the drive transformer, and the secondary winding of the current transformer is inserted in series between the commonly connected filaments of both discharge lamps. , it is possible to obtain a predetermined preheating current at a desired frequency with a simple configuration, and it also prevents discharge lamps from coming off,
Even if a current flows through the secondary P5 wire of the current transformer above the circuit, since another impedance element is connected in parallel to the secondary winding, the voltage generated in the secondary winding can be reduced.
As a result, it is possible to prevent the switching element from being destroyed due to abnormal voltage being induced in the frequency correction winding.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of the present invention, FIGS. 2 to 6 are circuit diagrams of a conventional example, and FIGS. 7 and 8 are waveform diagrams for explaining the operation of the circuit shown in FIG. is a discharge lamp, T is a drive transformer, nl is a primary winding, n2, I+3 are secondary windings, Q,, Q2 are transistors, T is a current transformer, nco+ is a primary winding, n32 is a Secondary windings 1 and 3 are secondary windings for frequency correction, Z is an impedance element, R is a filament resistor, C1 is a capacitor, and Ll is a choke. Agent Patent Attorney Ishi 1) Ai Shichi Q3 Figure 3 Figure 7 X ×

Claims (2)

[Claims] (1) A switching element for oscillation, a current-limiting impedance element connected to the power supply side end of the filament of the discharge lamp, and a primary winding through which current flows through the impedance element or the discharge lamp, and a control terminal of the switching element. and a drive transformer having a secondary winding that drives the switching element, forming at least an inverter circuit;
In a discharge lamp lighting device that lights two discharge lamps connected in series using the high frequency output of the inverter circuit, the primary winding of the current transformer is turned on for a predetermined time after power is turned on, and turned off after a predetermined time elapses. A series circuit with a switch element is connected between the other end of the filament on the non-power supply side, one end of which is connected to the power supply side of both discharge lamps, and the current transformer constitutes a current source that is a determining factor of the oscillation frequency of the inverter circuit. A frequency correction winding is inserted into a feedback circuit formed by the control terminal of the switching element and the secondary winding of the drive transformer, and the secondary winding of the current transformer is inserted between the commonly connected filaments of both discharge lamps. 1. A discharge lamp lighting device characterized by having another impedance element inserted in series and connected in parallel to the secondary winding. (2) The impedance value Z_0 of the other impedance element is determined by the relationship between the series resistance value R of the commonly connected filaments of both discharge lamps and the inductance value L' of the secondary winding of the preheating transformer: R<Z_0 <ωL' (however, ω=2
7. The discharge lamp lighting device according to claim 1, wherein the discharge lamp lighting device is configured to have a setting of πff: oscillation frequency).