JPS62200688A - Discharge lamp burner - 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 1g and a lamp device that light a discharge lamp using an inverter circuit.

[Background technology]

Conventionally, in this type of discharge lamp lighting device, a discharge lamp is lit by an inverter circuit whose load is a series resonant circuit consisting of an inductance element, a capacitor, and a discharge lamp, and the discharge lamp and the power supply side are non-insulated. An abnormality protection means is provided that detects an abnormality in the discharge lamp at the end of its lamp life and limits or stops the oscillation of the inverter circuit.

Figure 4 shows a conventional example (Japanese Patent Application No. 61-5243), in which transistors Q, , Q, which are switching elements connected in series, are connected to a power switch S for a DC power supply E.
are connected in parallel via W0, and transistors Q,
A load including a discharge lamp is connected in parallel to the collector of the discharge lamp via a capacitor C1. As described later, this capacitor CI inverts the voltage supplied to the load when the two transistors Q, Q2 turn on and off alternately, cuts the DC component, and supplies the AC component (high frequency power) to the load. It has the effect of Further, a capacitor C2 is connected in parallel with the discharge lamp t, and an inductance element R is connected to the connection point of this capacitor C2 and each discharge lamp (on the opposite side of the capacitor C1), thereby forming a series resonant circuit A. There is. Here, two capacitors C,, C2 are C,
) satisfies the relationship C.

The non-load side terminal of the inductance element R is connected to the transistor Q, , Q, through the primary winding nl of the drive transformer T.
Furthermore, the two large windings @n 2 and n 3 of the drive transformer T are connected to the bases of the transistors Q, , Q, respectively via resistors R1 and R2. In addition, two large windings of the drive transformer T, #i in
2111s has its polarity reversed and becomes transistor Q.
, Q2 are turned on and off alternately, and the drive circuit 2 is constituted by this drive transformer T and its auxiliary circuits. A voltage dividing circuit constituted by a series circuit of resistors R9 and R6 is provided between the connection of the capacitor C3 to the discharge lamp α and the negative terminal of the DC power supply E, and this enables voltage detection. A circuit section 3 is configured. Here, the resistor R6 and the resistor R6 are selected to have impedance values relative to the load. Furthermore, resistor R7
The connection point between and resistor R6 is connected to the base of transistor Q through Zener diode ZD and resistor R, and the collector of transistor Qs is connected to resistor R5 and resistor R.
6 connection points. The emitter of the transistor Qs is connected to the negative terminal side of the DC power supply E. The comparison circuit section 4 is composed of the transistor Q9, the Zener diode ZD, and its attached circuits. Further, the base of transistor Q is connected to the collector of transistor Q5 via resistor R8, and the collector of transistor Q is connected to the date terminal of thyristor SCH via resistor R9 and the power supply side of capacitor C1 via resistor R4. has been done. Also, the emitter of transistor Q4 is connected to thyristor SC.
It is connected to the negative terminal side of the DC power supply E in common with the cathode of R. The 7 nodes of the thyristor SCR are connected to the power supply side of the capacitor CI via a resistor R3, and are also connected to the 7 nodes via a diode D and one end of the winding n of the drive transformer T. The other end of the winding n4 of the drive transformer T is connected to the negative terminal side of the DC power supply E. The output control section 5 is composed of the transistor Q4, the thyristor 5CR1 driving transformer T, the winding n4 of the thyristor 5CR1, the diode Ds, and its attached circuits.

On the other hand, a resistor R1 and a capacitor C are connected in parallel with the DC power supply E, and a diode D is connected between the connection point of the capacitor C2 and the resistor R3 and the connection point of the transistors Q, , Q. Connected. This diode D has its 7th node connected to the connection point of the resistor R1 and the capacitor C7 as shown in the figure. Then, resistor R3 and capacitor C
A diac Q is provided between the connection point of the transistor Q2 and the base of the transistor Q2.
On the other hand, when the starting ml path 6 is connected to HItrffiL, the series circuit of resistor R3 and capacitor C constitutes a diac Q, and the diode D and diac Q constitute a circuit.
A bypass circuit is configured to directly guide the current supplied from the DC power supply E to the transistor Q2 via the resistor R1 after the breakover occurs. Note that the transistors Q,,Q
, are connected in antiparallel with feedback diodes D1, D2.

Next, the operation of the above conventional example will be explained. When the discharge lamp 1 reaches the end of its lamp life, the active material on one filament is completely peeled off, resulting in a "DC, 4-lamp" state due to discharge in only one direction, and due to its polarity, the discharge lamp 1 becomes equivalent to Figure 5. (
, )(b). In the case of "DC lighting" as shown in Fig. 5(a), the potential at point 811 n of drive transformer T1 by applying a date current and turning it on.
4 is shorted and the inverter circuit stops oscillating.

Further, in the case of "DC lighting" as shown in FIG. 5(b), the potential at point X becomes 2E, so that Zener diode ZD is turned on and transistor Q5 is also turned on. When transistor Q is turned on, transistor Q4 is turned off, and thyristor SCR is turned on as in the case of FIG. 5(a).
turns on, the inverter circuit stops oscillating. However, in this case, even if the discharge lamp l is replaced while the power is on, it is impossible to turn on the discharge lamp l because the function of stopping the oscillation of the inverter circuit is maintained.

Here, as a conventional example that solves the above drawbacks, there is a discharge lamp device shown in FIG. 6, and the basic lighting operation of this circuit is as follows.
41st! This is almost the same as the conventional example of I, but a resonance capacitor C2 is connected to the non-power supply side of the filaments f, f2 of the discharge lamp I. Further, the resistor R0 is a voltage-dependent resistor, and no current flows during normal lighting. In this circuit, for example, at the end of the lamp life, a current flows through Ro which depends on the voltage, so that the element Q is turned on and the thyristor 5CR2 becomes conductive. Therefore, the 8 #i n- of the drive transformer T is short-circuited, and the oscillation of the inverter circuit is stopped. Also thyristor 5CR2
The holding current flows through one filament (f+) of the discharge lamp l by the direct power source E, so that the oscillation is maintained stopped. However, when the discharge lamp 1 is removed in order to replace it, the holding current flowing through the filament f1 of the discharge lamp 1 is cut off, so the state in which oscillation is stopped must be reset. Next, when a new discharge lamp 1 is connected, it becomes possible to light the lamp again. However, even in such a conventional example, in the case of two discharge lamps connected in series, that is, in the case of a lamp configuration as shown in FIG. 7, the holding current when the thyristor 5CR2 is made conductive is Since the current flows only through one filament of the discharge lamp 11, the oscillation of the discharge lamp 1 is stopped when the discharge lamp 1 reaches the end of its lamp life.
Even if the discharge lamp 12 is replaced thereafter, the holding current for stopping oscillation cannot be cut, so the same problem as in the conventional example shown in FIG. 4 occurs, in that the oscillation of the inverter circuit remains stopped and the lamp cannot be lit again. Further, in the conventional example shown in FIG. 6, since the resonant capacitor C2 is connected to the non-power supply side of the inverter circuit, the preheating current flows to the filament L-rt of the discharge lamp l via the resonant capacitor C2. Therefore, even after the discharge lamp is turned on, current continues to flow through the filament L-L of the discharge lamp L through the resonance capacitor C2, even though the resonance mode changes, and this is essentially a waste of current. become.

As mentioned above, there are many circuits that forcibly suppress abnormalities in discharge lamps at the end of their lamp life.
When replacing the discharge lamp, there was no such thing as turning on the power and completely restarting the discharge lamp by replacing it.

[Object of the Invention] The present invention has been made in view of the above-mentioned points, and its purpose is to replace a discharge lamp that is abnormally lit, such as Emiles, when the power is turned on. Even if the discharge lamp is replaced, the malfunction protection measures must be maintained:
1llll! To provide a discharge lamp lighting device which can automatically reset the function and relight the lamp.

[Disclosure of the Invention J (Structure) The present invention is composed of an inverter circuit whose load is a series resonant circuit consisting of an inductance element, a capacitor, and a discharge lamp, and detects an abnormal lighting state of a discharge lamp at the end of its lamp life. In a discharge lamp lighting VC system equipped with abnormality protection means to limit oscillation, the filament of the discharge lamp is
A switch is provided on the I4 source side, and by closing the switch, a discharge loop of the capacitor is formed through the filament of the discharge lamp, and when the discharge lamp is removed and the discharge loop is cut off, the potential difference of the capacitor is detected. Even when the power is on, replacing the discharge lamp resets the IQ function of the above-mentioned abnormality protection means, and is equipped with a reset circuit that enables the lamp to be lit again. At the time of replacement, even if the discharge lamp is replaced with the power turned on, the retaining w1 function of the abnormality protection means can be automatically reset and the lamp can be lit again.

(Embodiment 1) FIG. 1 is a block circuit diagram showing one embodiment of the present invention,
Is DC power supply E AC? l! Did you rectify the source and make it constant voltage? l!
It is composed of sources, etc. The switching elements Q, Q2 connected in series with the DC power source E are alternately turned on and off by the drive circuit section 3. In addition, the switching element Q,
Connect a series circuit of a capacitor C0, a discharge lamp L, and an inductance element L in parallel with the filament L of the discharge lamp L.
A capacitor C2 is connected in parallel to the power supply side terminal of -fz, and a switch SW is connected to the non-power supply side terminal. Next, reset circuit 1 is a discharge lamp! It is constituted by a voltage divider circuit using a resistor element having an impedance considerably higher than that of the capacitor C3, and is connected between the non-power supply @ terminal X of the capacitor C3 and the e terminal of the DC type rLE. The output control circuit 2 receives a signal from a circuit 4 that detects an abnormality during the life of the lamp, such as EMIRES lighting, and supplies a signal to the drive circuit 3 to limit oscillation, and also outputs a signal to limit the oscillation of the filament of the discharge lamp (r). 'FlW
This provides a signal to close the switch SW provided on the i side.

Next, we will explain the operation of the above circuit.1 Normal case:
When the power switch is turned on, the switching elements Q, Q are turned on and off alternately by the drive circuit section 3, and the discharge lamp l
lights up. Here, when the discharge lamp 1 reaches the end of its lamp life, such as when the discharge lamp 1 reaches the end of the lamp life, a current flows through the inductance element L1, causing a phenomenon of polarized magnetization or an overcurrent flowing. For this purpose, the state is detected by the EMIRES detection circuit 4, and the output control circuit 2 gives a signal for forcing the drive circuit section 3 to oscillate, and closes the switch SW provided on the non-current side of the discharge lamp 1. Then capacitor C1
and the switching element Q, an impedance Z, an inductance element L1, a filament f2, which are connected in parallel with the switching element Q.
Capacitor C via switch SW and filament rI
5 is partially discharged, and the charging voltage of the capacitor C8 becomes lower than the magnitude of the DC power supply E. Conversely, the reduced amount of the 'Il source becomes the potential at point X when viewed from the e terminal of the DC power supply E. The reason is that if the size of the DC power supply E is e, then e=C
, and the potential at point X. Therefore, in this state, X and α have potentials. When the primary discharge lamp l is removed to be replaced, the above-mentioned discharge loop is cut off, and the capacitor C3 has a voltage of e, which is the same as the DC power supply. is charged, and the potentials of x and g become Ov. The reset circuit 1 detects that this voltage becomes Ov, and resets the abnormality protection operation (limiting oscillation and simultaneously closing the switch SW) of the output control circuit 2 received from the lamp life abnormality detection circuit 4. Therefore, discharge lamps next! If you connect it, you can turn it on again.

The impedance Z does not need to be connected in parallel with the switching element Q1. For example, if the lamp life is detected and the oscillation is to be shifted significantly from the resonant frequency of the inductance element L+ and capacitor C2, the switch The discharge lamp l for closing SW enters the preheating state, and the discharge loop of the capacitor C2 (switching element Q0, inductance element L I s discharge lamp 1
．． filament f2, switch SW, filament f
1) and has a load due to its function, the potential of point Filament r,,r of discharge lamp l.

Any circuit that provides a potential to the point X via the circuit may be used.

Figure 2 shows a concrete example, including a DC power supply E1, diodes D and D2, transistors Q and Q2, capacitors C2C5, and a discharge lamp! , the inductance element L1, and the drive transformer T constitute a series resonant inverter circuit. Also, resistor R1, capacitor C1, diac Q
, and diode D, with.

It constitutes the starting circuit. The switch SW is also used as a preheating switch, and uses the normally closed contact of the relay Ry, which is controlled by the transistor Q.

This is done by turning on and off. The preheating timer circuit is composed of a resistor R2, a capacitor C2, a resistor R1R1, and a comparison circuit IC, and one time period of the timer is determined by the charging voltage of the capacitor C1 and the divided voltage of the resistors R and R. Furthermore, the output turns on and off the transistor Q, and connects the impermeable date, and when the output is "H", the capacitor C is connected through the resistor R5.
1 is charged. Here, it is assumed that the time constant of the resistor R5s and the capacitor C1 satisfies the following conditions.

Time constant of R5/C6) Time constant of R2/C4 Next, a comparator circuit that compares the charging voltage of the capacitor C9 and the divided voltage of resistors R and R4 ■C2 output is connected to the base of transistor Q6 with resistor 6, diode D, It is also input via a diode I)s and a resistor R15 to the base of the transistor Q4.
Input via .

Furthermore, the circuit that limits oscillation is a drive transformer T.

One of the quaternary windings n4 is connected to the e terminal of the DC power source E1, and the other is connected to the diode D, and the DC power source E is connected via the transistor Q6.
It is connected to the θ terminal of 1. Control of this transistor Q depends on the detection circuit 4. The detection circuit 4 has both no-load detection and EMIRES detection. In addition, the reset circuit 1 includes a resistor R12 and a Zener diode ZD.
2 and an inverter circuit) IC, the output of which is connected to the base of a transistor Q5 via a resistor R13, and the transistor Q5 is connected to both ends of a capacitor C7. Further, the DC power supplies E and E2 have the same e terminal, and a voltage can be obtained at the same time as the power is turned on.

Next, the operation of this circuit will be explained.

When the lamp lights up normally> When the power is turned on, a starting pulse is given to the base of the transistor Q2 by the starting circuit (Rl-C, -Q x ), and the inverter circuit starts oscillating. At the same time, the switch SW is closed because it is formed by the normally closed contact of the relay Ry, and the switch SW remains closed until the charging voltage of the capacitor C4 becomes higher than the divided voltage of the resistors R, , R,
W is closed and preheated during that time. After that, when the charging voltage of the capacitor C4 becomes higher than the divided voltage, the output of the comparison circuit IC+ becomes 'H', and the switch SW opens and lights up.Here, I will explain in detail the moment when the power is turned on.
The potential at point X with respect to the e terminals of the DC power sources E and E2 is determined by the discharge loop of the capacitor C2 being connected to the resistor R1t, the diode D,
Capacitor C2 is made of inductance element R, filament f2, switch SW, and filament f.
has a potential slightly lower than that of the DC power source E1, so E
, = potential of capacitor C2 + potential of point X Therefore, point X has a certain potential.

Depending on the voltage, diode D5, resistor R1°, resistor R
, by turning on transistor Q7 through
The circuit that stops oscillation stops working, and the activation pulse starts oscillation.

<In case of no load> When the power is turned on, a starting pulse is applied from the starting circuit to the base of the transistor Q2, but since there is no discharge lamp l, the voltage of the DC power supply E1 is applied to the capacitor C2. Therefore, the potential at point However, since the winding Mn4 is short-circuited, no oscillation occurs. At the same time, the transistor Q is turned on from the DC power supply R2 via the resistor R7, the diode D1, and the resistor RI5, so the output of the comparator circuit IC is Therefore, if the transistor Q is off and the switch SW is closed, if the discharge lamp I is connected in that state, the discharge loop (
R+ −D 3− n + = L−4f 2− S
W→r+) is formed, so the potential of the capacitor C2 decreases and a potential appears at the point X. For this purpose, the transistor Q7 is turned on, the transistor Q6 is turned off, and the transistor Q4 is turned off, and oscillation is started by the starting pulse to enter a preheating state, and after a certain period of time, the switch SW is opened and the light is turned on.

In the case of abnormal lighting such as EMIRES lighting at the end of the lamp life> When EMIRESS lighting occurs at the end of the lamp life, the detection circuit 4 turns off the transistor Q7 (the reason is the same as the conventional example in Figure 4). be). That is, when one of the filaments becomes emissive, the voltage divided by the resistors R5 and R1 becomes approximately 0.times., the transistor Q6 is turned on and the silannostar Q is turned off. For this operation, the transistor Q6 is turned on from the DC power supply E2 via the resistor R and the diode D, and at the same time as the oscillation stops, the transistor Q4 is turned on, the output of the comparator circuit I C+ becomes L'', and the transistor Q is turned on. Turn off the lamp and close the switch SW.Then, the situation changes from no-load to the same as when the discharge lamp 1 is connected, oscillation resumes, the lamp is in a preheating state for a certain period of time, and it attempts to light up.

Then, the state becomes Emiless again, and the above operation is repeated. At that time, the output of the comparator circuit ■C1 becomes “I”.
”, ’L” will be repeated, and it will be in-tweeter day)
IC,, capacitor C5 is gradually charged by resistor R9,
When the charging voltage of the capacitor C5 becomes larger than the divided voltage of the resistor R: lt R, the output of the comparator circuit IC7 becomes "■"
Therefore, the transistor Q6 turns on and stops oscillation, and the transistor Q4 turns on via the diode D resistor R15, and the voltage of the capacitor C4 becomes O.
Therefore, the output of the comparison circuit IC1 becomes "L", and the switch SW is closed. This state is maintained as long as the capacitor C5 is not charged. In addition, in the inverter circuit where oscillation has stopped, since the discharge lamp l is still attached, the discharge loop of the capacitor C2 (R0 → D, → nl
-4f2→5W-4f,), the voltage across the capacitor C2 is slightly reduced compared to the DC type riE, and therefore the reduction is shown in the potential up to point X.

Since the Zener voltage of the Zener diode ZD2 in the reset circuit 1 is determined to be lower than the voltage at the point X when the light is on, the output of the inverter IC4 is in the "L" state as when the light is on. However, when the discharge lamp 1 is removed, the discharge loop of the capacitor C2 disappears, so the voltage of the DC power supply E is applied to the capacitor C2, and the potential at point X becomes OV. Then, reset circuit 1
The potential of the zener switch)'ZD also becomes 0, and the output of the inverter data)rc becomes "H".

In response to this signal, the transistor Q connected to both ends of the capacitor C5 turns on, and the output of the comparator circuit rC2 becomes "H".
'', and the signal that causes the oscillation to stop and the switch SW to close is released. However, in this embodiment, the oscillation is stopped and the switch SW is closed even when there is no load, so the operation remains the same. Next, when the discharge lamp p is reinserted, a discharge loop of the capacitor C2 is formed again, voltage appears at When the discharge lamp 1 is reinserted and the voltage at point A switch SW is provided on the non-power side of the filament (filament), f2, and by closing the switch, a discharge loop of the capacitor C2 is formed via the filament (f), f2 of the discharge lamp, and the discharge lamp l is removed. By resetting the operation of stopping the oscillation and closing the switch SW, the state is made the same as when there is no load, and when the discharge lamp I is replaced, restarting is possible when a new discharge lamp I is inserted. Furthermore, in this circuit, the switch SW, which closes the preheating switch when an abnormality occurs at the end of the lamp life, is shared, and the reset circuit 1 also has a very simple configuration.

Although this circuit is an embodiment using a self-excited inverter circuit, a separately excited inverter circuit may also be used, and oscillation does not necessarily have to be stopped when no load is applied.

(Embodiment 2) Fig. 3 shows another embodiment, and this circuit consists of AC type ri, Eo, t-1'DIID2, and smoothing fan Y.
The power supply for the inverter circuit is generated by a voltage doubler rectifier circuit consisting of sensors C, ,C. The inverter circuit is a separately excited type oscillation, and its oscillation frequency "b" is set slightly lower than the natural oscillation frequency of the inductance element I53 and capacitor C1, and is designed to be quantitative at no load. shall be.

? [E and R2 are? It is assumed that this is obtained at the same time as the Ii source switch is turned on. Also, the time constant of the capacitor Cs with a resistor R, which sets the preheating timer for one hour, is the resistor R2,
It is assumed that the time constant of the capacitor C is very short compared to the time constant of the capacitor CA. Furthermore, in the oscillation circuit, a timer circuit rcs (for example, Intersil's ICM7555) is used to create an astable 9. Configure the withdrawal path and connect its output to the timer circuit IC (for example, the old 401: () IC,
A frequency dividing circuit is formed by the NAND date IC and IC1. The resistor RIM is for providing a time delay. In addition, the oscillation frequency can be changed by dividing the voltage at pin 5 of the timer 1ijl path rC6.
In this case, the oscillation frequency increases compared to when transistor Q is on.

Next, the operation of the embodiment shown in FIG. 3 will be explained.

In the case of normal lighting> After the power is turned on, the output of the comparator circuit is L'' and the transistor Q is turned off until the voltage charged in the capacitor C6 via the resistor R1 exceeds the divided voltage by the resistors R1 and R6. However, as the switch SW closes, the oscillation frequency oscillates at the frequency fa since the transistor Q6 is off, and a preheating current flows through the discharge lamps II and lx.At this time, the lamp current detection circuit In order to detect the preheating current, the output of the inverter date IC becomes 'L'.

In addition, the output of the inverter IC9 of the reset circuit 1 is also L''.Then, the output signal of the comparator circuit IC becomes H'', the transistor Q3 is turned on, and the switch SW is turned on.
When the transistor Q6 opens, the transistor Q6 turns on and oscillates at the oscillation frequency fb. At this time, since the frequency rb is set slightly lower than the resonant frequency of the choke coil L1 and the capacitor C4, a high voltage is generated across the capacitor C4, and the discharge lamp l is lit. Even in the lit state, the outputs of the inverter IC4 and IC5 do not change, and both are #L''.

When the discharge lamp L is removed from the normal α-lamp state, no current flows through the primary @ wire of the transformer T of the lamp current detection circuit, and the potential at point A becomes zero. The output of the inverter date IC becomes 1H'', and when the transistor Q is turned on, the output of the comparator circuit IC becomes H'', the switch SW is turned on, and the oscillation frequency becomes fa, as in the case of preheating. This lowers the secondary voltage at no-load.Next, when the discharge lamp r is inserted again, it enters the preheating state, current flows through the primary winding of the transformer T1, and a voltage is generated at point A.
Inverter data) IC, output becomes 1L#, so
The capacitor C6 is charged via the resistor R4, and the operation is the same as when turning on the alpha lamp in normal conditions.

When a discharge lamp reaches the end of its lamp life, it turns on as a semi-DC lamp, similar to a semi-direct current lamp. At this time, the current flowing through the primary winding of the transformer T of the lamp voltage detection circuit becomes very small, so the output of the inverter date rc becomes "H", the transistor Q4 turns on, and the output of the comparator circuit IC becomes #L. '', the switch SW turns off, the transistor Q turns off, and the oscillation frequency also becomes fa. However, since the filament members f, , f of the discharge lamp L are all still inserted, preheating oscillation occurs again, and the output of the inverter IC, which is the output of the lamp current detection circuit, becomes low.
It will be preheated for a certain period of time. Thereafter, when the output of the comparison circuit IC becomes H, the switch SW opens and the oscillation frequency also becomes fb. However, the EMIRES lighting is turned on again, so the above operation is repeated.

At this time, the output of the inverter IC, which received the output of the comparison circuit IC+, repeats 'H' and 'L'', thereby charging the capacitor C7 via the resistor R7, and the charging voltage is applied to the resistor R. ,, When the voltage becomes higher than the divided voltage by R9, the output of the comparison circuit IC2 becomes H", the transistor Q4 is turned on, the switch sw is closed, and the oscillation frequency becomes "a" without preheating. At this time,
The potential at point X has a voltage because it performs preheating oscillation. However, when the discharge lamp 1 is removed, there is no load current in the circuit, and the power supply voltage of the inverter circuit is directly applied to the capacitor C3, so that the potential at point X becomes 0. Therefore, the potential of 7αB also becomes Ov, and the output of inverter data) rc is H'' and transistor Q.

is turned on, capacitor C2 is immediately discharged, and comparison circuit I
The output of C2 becomes L. However, discharge lamps! Since the inverter IC1 is removed, the output of the inverter IC1 becomes H'', and the transistor Q.

remains on, which is the same as the no-load condition. Therefore, by reinserting the discharge lamp 1, it becomes possible to restart the system.

In the case of normal lighting> After the power is turned on, the output of the comparator circuit IC is "L" and the transistor Q is turned off until the voltage charged in the capacitor C6 via the resistor R1 exceeds the divided voltage by the resistors R6 and R6. However, when the switch SW is closed, the oscillation frequency oscillates at the frequency fa since the transistor Q6 is turned off, and a preheating current flows through I and α2 of the discharge lamp. At this time, the lamp current detection circuit detects the preheating current from the transformer T, so the output of the inverter IC1 becomes "L". In addition, the output of the inverter data (IC) of the reset circuit 1 is also “L”.
". After that, the output signal of the comparator circuit IC becomes "H".
'', transistor Q is turned on, switch SW is opened, transistor Q6 is turned on, and the oscillation frequency f is
oscillate b. At this time, since the frequency rb is set slightly lower than the resonant frequency of the capacitor C4, which is a choke coil, a high voltage is generated across the capacitor C1, and the discharge lamps Q, . . . , Q2 are lit.

Even when the lights are on, the inverter data) Ic,,
The outputs of rc and rc do not change, and both are "L".

When the discharge lamp α110, 2 is removed from the normally lit state as described in iv, the current will no longer flow through the primary winding of the transformer T of the lamp current detection circuit, and the potential at point A will be reduced. disappears, the output of the inverter (data) IC becomes H", and the transistor Q
, turn on. Then, the output of the comparator circuit IC becomes "L", and the switch SW closes as in the case of preheating, and the oscillation frequency also becomes fa. As a result, when the discharge lamp αIll is inserted again, a preheating state is established, and a current flows through the primary winding of the transformer T, causing a point A.
A voltage is generated, and the output of inverter date IC4 becomes L”
Therefore, the capacitor C6 is charged by the resistor R1, and the operation is the same as when lighting is performed normally.

Discharge lamp α1. When α2 reaches the end of its lamp life, it becomes like semi-DC lighting called Emiles lighting. At this time, the current flowing through the primary winding of the transformer T of the lamp current detection circuit becomes very small, so the output of the inverter IC,
becomes high, transistor Q turns on, and comparison circuit IC
Since the output of the transistor Q1 becomes "L", the switch SW is closed, the transistor Q6 is turned off, and the oscillation frequency also becomes fa. However, the discharge lamp α8. e2 filamen) r
+, f2 are all still inserted, so the preheating oscillation starts again, and the output of the inverter IC, which is the output of the lamp current detection circuit, becomes 'L', and the comparator circuit IC is preheated for a certain period of time. , becomes "H", the switch SW opens and the oscillation frequency becomes fb.

However, the above operation is repeated because the EMIRES lighting is turned on again. At this time, the output of the inverter IC3 which received the output of the comparison circuit IC6 becomes 'H', the transistor Q is turned on, the switch SW is closed, and the oscillation frequency is fa and there is no preheating.At this point, The potential of X has a voltage because it performs preheating oscillation.However, when discharge lamp ηItQ,2 is removed,
Since there is no load current in the circuit, the power supply voltage of the inverter circuit is directly applied to the capacitor C1, so the potential at point X becomes O. Therefore, the potential at point B becomes 0■, the output of inverter date C5 is H'', transistor Q is turned on, capacitor C7 is immediately discharged, and the output of comparison circuit IC2 becomes "L".However, the discharge lamp Since αl*Q2 is removed, the output of the inverter IC4 becomes "H", and the transistor Q remains on, resulting in the same state as the no-load state.
Discharge lamp 0. Reinserting l+0.2 allows restart.

[Effects of the Invention] As described above, the present invention is composed of an inverter circuit whose load is a series resonant circuit consisting of an inductance element, a capacitor, and a discharge lamp, and detects an abnormal lighting state of a discharge lamp at the end of its lamp life. In a discharge lamp lighting device equipped with an abnormality protection means for limiting oscillation, a switch is provided on the non-power side of the filament of the discharge lamp, and by closing the switch, a discharge loop of a capacitor is formed through the filament of the discharge lamp. By detecting the potential difference of the capacitor when the discharge loop is interrupted by removing the discharge lamp, the abnormality protection means can be maintained by replacing the discharge lamp even when the power is on. 8! This device is equipped with a reset circuit that resets the function and enables re-lighting, and when replacing a discharge lamp that is abnormally lit by Emires etc., when replacing the discharge lamp with the power turned on. Also, the reset circuit has the effect that the protection function of the abnormality protection means can be automatically reset and the lighting can be restarted.

[Brief explanation of drawings]

Fig. Pt51 is a block circuit diagram showing one embodiment of the present invention, Fig. 2 is a specific circuit diagram of the same as above, Fig. 3 is a specific circuit diagram of another embodiment, Fig. 4 is a circuit diagram of a conventional example, and Fig. 5 is a block circuit diagram showing an embodiment of the present invention. 6 is a circuit diagram of another conventional example, and FIG. 7 is a diagram showing problems in the conventional example shown in FIG. 6. Q,, Q2 is a switching element, t is a discharge lamp, 2 is a filament, L is an inductance element, C,
, C2 is a capacitor, SW is a switch, and 1 is a reset circuit. Agent Patent Attorney Ishi 1) Chief 7 Figure 1 η Figure 5 (G) (b) Figure 6 B4

Claims (2)

[Claims] (1) It consists of an inverter circuit whose load is a series resonant circuit consisting of an inductance element, a capacitor, and a discharge lamp, and is equipped with an abnormality protection means that detects abnormal lighting conditions of the discharge lamp at the end of its lamp life and limits oscillation. In the discharge lamp lighting device, a switch is provided on the non-power side of the filament of the discharge lamp, and by closing the switch, a discharge loop of a capacitor is formed via the filament of the discharge lamp, and when the discharge lamp is removed, the discharge loop is closed. The discharge lamp is characterized by being equipped with a reset circuit that detects the potential difference of the capacitor when the lamp is cut off and resets the protective function of the abnormality protection means by replacing the discharge lamp even when the power is on, thereby making it possible to restart the lamp. Electric light lighting device. (2) The discharge lamp lighting device according to claim 1, wherein the switch and the preheating switch are shared.