JPS63160195A - 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 for lighting a plurality of discharge lamps in parallel at high frequency.

(Background Art) FIG. 11 is a circuit diagram of a conventional discharge lamp lighting device. The power supply voltage of the AC power supply AC is rectified by the diode bridge DB and smoothed by the capacitor C2, and the DC voltage to be made into a DC voltage is generated by the connection between the primary side of the oscillation transformer OT consisting of a leakage transformer and the transistor Tr+. applied to the series circuit.

A discharge lamp D L + is connected to the secondary side of the oscillation transformer OT via a capacitor C3 and a balancer transformer T.

DL2 are connected in parallel, and actance elements (capacitors C4 and C5) are connected to the non-power side of each discharge lamp DL, DL2, thereby forming a discharge lamp filament preheating circuit. A diode D is connected in antiparallel to the transistor Tr+. In addition, the capacitor C2, which exhibits a resonance state with the inductance component of the circuit, is connected to the transistor Tr+.
Connect in parallel to both ends.

The capacitor C2 may be connected to both ends of the primary coil of the oscillation transformer OT. transistor T
The oscillation output of the control circuit 3 is inputted to the base of r+ via the drive circuit 6, thereby controlling the on/off state of the transistor Tr+.

When the transistor Trl is turned on, the oscillation transformer OT
A collector current flows through the transistor Tr+ through the primary side of the transistor Tr+. When the transistor Trl is turned off, the oscillation transformer OT resonates with the capacitor C2 due to the energy stored in the LC component of the circuit, a resonant capacitor current flows, and a resonant voltage is generated between the collector and emitter of the transistor Tr +. arise. When this resonant voltage becomes zero, a resonant current flows through the diode D, and when the diode current becomes zero, the transistor Trl is turned on and current flows as in the previous cycle. In this way, oscillation continues. As a result, the voltage generated on the secondary side of the oscillation transformer OT is applied to the discharge lamps DL+ and DL2 via the leakage inductance of the oscillation transformer OT, the capacitor C3, and the balancer transformer T, and the discharge lamps D L + and D L 2 are lit in parallel.

In this conventional example circuit, by changing the frequency of the passive signal, the current flowing through the transistor Tr+ changes, so the resonant current value changes, and the discharge lamps DL, DL
2, the voltage applied to the discharge lamp DLI can be changed
, a preheating state in which DL2 is not lit, and a lighting state.
It is possible to set a dimming calendar.

For example, when the power is turned on, the on period of the transistor Trl is shortened. As a result, the transistor Tr
The collector current peak value when l is turned off is lowered, the stored energy of the oscillation transformer OT is reduced, and therefore,
Since the oscillating voltage with the capacitor C2 becomes low, the secondary voltage of the oscillation transformer OT is lowered to below the discharge starting voltage of the discharge lamps DLI and DL2, thereby increasing the discharge lamps D L + ,
A filament current flows through the capacitors C3 and C< connected in parallel to DL2, and the filaments of the discharge lamps DL, DL2 are preheated.

After that, by increasing the on period of the transistor Trl, the secondary voltage of the oscillation transformer OT is increased, and the discharge lamp D
Turn on L, DL2. Increasing the on period in this way means that the off period is constant, so the oscillation frequency also changes, and the oscillation frequency decreases. Further, dimming can also be performed by shortening the on period of the transistor Trl from the lighting state.

In the balancer transformer T1, when one of the discharge lamps is lit, a high voltage is applied to the other discharge lamp due to the unbalance of the current flowing through each winding, so that both lamps are stably lit. When the two lamps are on, the current flowing through each winding is almost the same, and the balancer transformer T has almost no inductance component. In such a configuration, even if one lamp does not turn on due to some reason (life of the discharge lamp, incorrect installation of the discharge lamp in the lamp socket, etc.), the other lamp will not turn on. This is convenient for those who are in a position to use the lamp, as it does not cause both lights to go out when one lamp goes out.

In this conventional example, when two lamps are installed, the control circuit 3 controls the operating frequency as shown in FIG. 12, so that the voltage applied to the discharge lamp during the preheating period is lowered and the two lamps are discharged. The electric lamp is sufficiently preheated without cold cathode discharge, but when one lamp is installed, a voltage higher than the cold cathode discharge voltage is applied to the discharge lamp even during the preheating period, and one lamp If you use the lighting device while it is installed, the discharge lamp will be lit without sufficient advance preheating.
This poses a problem in that the life of the discharge lamp is shortened.

(Object of the invention) The present invention has been made in view of the above points, and
The purpose is to provide a discharge lamp lighting device in which a plurality of discharge lamps are lit in parallel at high frequency, in which each discharge lamp is appropriately preheated according to the number of lamps installed. It is in.

(Disclosure of the Invention) FIG. 1 is a diagonal diagram illustrating the basic configuration of the present invention. The voltage of the alternating current power supply AC is converted into a direct current voltage by a direct current conversion circuit 1, and becomes a direct current power supply E.

The output of this DC power source E is converted into a high frequency signal by a separately excited inverter circuit 2, and is applied to a parallel circuit of discharge lamps DLI and DL2 via a balancer transformer T. Capacitors C3 and C4 for preheating current control are connected in parallel to each discharge lamp, so that the filament current of the discharge lamp increases as the voltage applied to the discharge lamp increases.

In such a lighting device, the vibration frequency of the load changes depending on the number of normal discharge lamps installed. To explain the reason, for example, in the circuit of Fig. 1,
When there is only one discharge lamp DL, the capacitor C1 is connected to the load circuit via the filament of the discharge lamp DL, but when there are two discharge lamps DL, DL2, the capacitor C1 is connected to the load circuit through the filament of the discharge lamp DL. C4 and C9 are connected, and the capacity of the load circuit is doubled. In addition, each discharge lamp DL + , D
An actance element such as the balancer transformer T1 for almost balancing the current of L2 acts as an inductance component when one lamp is connected, but when two lamps are connected, the current cancels out and it no longer acts as an inductance component. Therefore, it is considered that the vibration frequency of the load circuit is completely different when one lamp is connected and when two lamps are connected, and if the number of lamps is different, the preheating conditions will be different. Therefore, in the present invention, the conditions for advance preheating are appropriately set depending on the number of lamps.

In FIG. 1, a lamp number determination circuit 5 determines the number of connected discharge lamps. Preheating state setting port #I4 is connected to the number of lamps discriminating circuit 5.
The oscillation frequency of the control circuit 3 is controlled according to the determination result. The separately excited inverter circuit 2 is driven by the passive signal outputted from the control circuit 3, and thereby appropriate preliminary preheating is performed according to the number of connected discharge lamps.

Examples of the present invention will be described below. In the circuit of the embodiment, the same elements as those in the conventional side exit path are denoted by the same reference numerals, and redundant explanation will be omitted.

Figure 2 is a circuit diagram of a discharge lamp lighting device according to an embodiment of the present invention. In this embodiment, a single-stone separately excited inverter is used as the inverter circuit 2. discharge lamp DLI
, a current transformer C for current detection is installed at the end of DL2.
T, , CT2 are connected to each other. The current transformers CT, CT2 detect a composite value of the lamp current and filament current of each of the discharge lamps DL, DL2, and thereby the number of installed discharge lamps can be detected.

The outputs of current transformers CT + and CT 2 are rectified by diodes D 2 and D s, and capacitor C
, 5, C, and 6, and input to the NAND gate G2.

Note that resistors R0, , R, , are connected in parallel to each of the capacitors Cl 5 + CI 6 . The output of the NAND gate G2 is "Higl+" level when one lamp is connected, and is "Lou+" level when two lamps are connected.
This constitutes the number-of-lights discriminating circuit 5.

In the control circuit 3, IC+ is an astable multivibrator, and IC2 to IC2 are monostable multivibrators, both of which are composed of a general-purpose timer IC "555". As is well known, this general-purpose timer IC has two trigger terminals.
When the output terminal (terminal No. 7) becomes 1/3 V cc or less, it is triggered and the output terminal (terminal No. 3) becomes 'High' level, and the discharge terminal (terminal No. 7') becomes high impedance. terminal) is 2/3Vcc
When this happens, the output terminal (terminal No. 3) becomes 'Lou+' level, and the discharge terminal (terminal No. 7) also becomes 'Low' level.

, the No. 1 terminal is an earth terminal connected to the ground level. Terminal 8 is a power supply terminal connected to power supply voltage Vcc. The No. 4 terminal is a reset terminal and is not used here, so it is connected to the power supply voltage Vcc.

A power supply voltage Vcc is applied to a series circuit of resistors R, , R2 and a capacitor c6, which constitute a time constant circuit of the astable multivibrator IC. The connection point between the resistor R3 and the resistor R2 is connected to the 7th terminal of the astable multi-by-break IC, and the connection point between the resistor R2 and the capacitor C6 is connected to the left half terminal and the 2nd terminal of the astable multi-by-break IC. connected to the terminal. Astable multi-by-break IC
The output terminal (terminal 3) of , is connected to the trigger terminal (terminal 2) of the monostable multivibrator ■C2.

A power supply voltage Vcc is applied to a series circuit of a resistor R3 and a capacitor C7 forming a time constant circuit of the monostable multivibrator c2. Resistor R3 and capacitor C7
The connection point with is connected to the 7th terminal and the 6th terminal of the monostable multivibrator IC2. The output terminal (terminal 3) of monostable multivibrator IC2 is connected to inverter G.
1 input. The output of inverter G1 is
It is connected to the base of the transistor Tr1 via a parallel circuit of a resistor R8 and a capacitor C82.

A power supply voltage Vcc is applied to a series circuit of a resistor R4 and a capacitor c8 and a series circuit of a resistor R5 and a capacitor C9, which constitute a time constant circuit of the monostable multivibrator IC3. The connection point between resistor R1 and capacitor C8 is
Connected to the 7th and 6th terminals of the monostable multivibrator ■C3.

The connection point between the resistor R5 and the capacitor C9 is connected to the second terminal of the monostable multivibrator C3. The output terminal (terminal 3) of the monostable multivibrator IC3 is connected to the base of the transistor Tr2 via a resistor R12, and is also connected to one input of an AND gate G3. The other input of AND gate G3 has NA
The output of ND gate G2 is connected, and the output of AND gate G3 is connected to one input of OR gate G4.

A series circuit of resistor R6 and capacitor c1o and resistor R7 that constitute the time constant circuit of a monostable multivibrator IC.
and capacitor c1. A power supply voltage Vcc is applied to the series circuit. The connection point between resistor R6 and capacitor C1o is the 7th terminal and 6th terminal of the monostable multi-high break IC.
connected to the number terminal. Resistor R7 and capacitor c11
The connection point with is connected to the No. 2 terminal of the monostable multivibrator C1. Monostable multivibrator IC
The output terminal (terminal 3) of , is connected to the other input of OR gate G. The output of the OR gate G4 is connected to the base of the transistor Tr) via a resistor R14. The collector and emitter of the transistor Tr3 are connected to both ends of a capacitor CI4, and the CR series circuit of the capacitor CI4 and the resistor R13 is connected to the resistor R.
1o and connected in parallel. The collector and emitter of the transistor Tr2 are connected to both ends of a capacitor C13, and the capacitor C33, resistor R11 and OC
The R series circuit is connected in parallel with the resistor R1o. A power supply voltage Vcc is applied to a series circuit of a resistor R4o and a resistor R9, which are connected in parallel with these CR series circuits. The connection point between the resistor R1° and the resistor R9 is connected to the non-inverting input of the operational amplifier C5.

The inverting input of is connected to the output of the operational amplifier ICs. The output of the operational amplifier IC5 is connected to the No. 5 terminal of the astable multivibrator IC.

The operation of the circuit of this embodiment will be explained below.

The astable multivibrator IC2 and the monostable multivibrator IC2 are connected to the main transistor T of the inverter circuit 2.
It constitutes an oscillation circuit for driving r+. An astable multivibrator IC is a monostable multivibrator with an operating frequency determined by the time constants of resistors R+, R2 and capacitor c6, and the input voltage of terminal 5.
A trigger signal from 1 to c2 is given to c2, and monostable multivibrator c2's output (terminal 3 voltage) remains 'HighI+' for a certain period of time determined by the time constant of resistor R3 and capacitor C7 after being triggered. The "High" level section remains constant regardless of the operating frequency of the astable multi-by-break IC.

The inverter G inverts the output of the monostable multivibrator E C2, and this output causes the transistor T to
It is driving rl. Astable multi-by-break IC,
The operational amplifier IC9 whose output is connected to the No. 5 terminal of the IC9 performs impedance conversion, that is, the voltage at the non-inverting input terminal becomes the output voltage as it is, and when this output voltage increases, the operation of the astable multi-by-break IC1 changes. The frequency is now decreasing. Repeat the above operation in the third step.
As shown in the figure.

Current transformers CTI and CT2 are discharge lamps DL, respectively.
The combined current of the lamp current and filament current of DL2 is detected, and while the inverter circuit 2 is operating, the discharge lamp D
If L+ is attached, a charging voltage will be generated in capacitor C15, and if discharge lamp DL2 is attached, capacitor C+. A charging voltage is generated.

Monostable multi-bibreak ICs C3 and IC4 have their output (terminal 3 voltage) in a “Hi” state for a certain period of time after the power is turned on.
The timer operates to reach the “gh” level.
The 'High' level period is determined by the time constant of resistor R4 and capacitor C8, and the time constant of resistor R6 and capacitor C1o, respectively. Here, the outputs of monostable multivibrator IC3 and IC2 are at 'High' level. It is assumed that the periods of time are set to, for example, approximately 1 second and approximately 0.1 second, respectively.

Consider a case where power is turned on in such a configuration. At this time, monostable multi-bibreak IC3, IC
The outputs of the monostable multivibrator C3 are both 1-transistor Tr2 and the monostable multivibrator IC.

The output turns on transistor Tr3 via OR gate G4. At this time, a voltage determined by the resistors R9 to R++ and R, +3 is applied to the non-inverting input terminal of the operational amplifier ICs, and its value is RA□ V cc
/ (R9+ RA) C However, RA = R1o
R+ + R+s / (R+ o R+ t + R
l+Rl3+Rl3R+o)), and the transistor Tr at the operating frequency determined by this value
, is driven. Note that the operating frequency at this time is set to a value that prevents the discharge lamp from starting regardless of the mounting state of the discharge lamp.

FIG. 4(a) is an explanatory diagram of the operation when only one discharge lamp is installed. In this case, NAND
Since one of the inputs of gate G2 is at High level and the other is at 'LOII+' level, its output becomes 'HiHb° level.This 'High' level output is a monostable multi-bibreak IC. ,'H
Since the output of the AND gate G becomes "High" level, the transistor Tr3 is turned on via the OR gate G4.During this period, the monostable multi-by-break The output of IC4 will start approximately 0.1 seconds after the power is turned on.
The level is Lou+"'.

Therefore, transistor Tr2. Both Tr and Tr are turned on for about 1 second after the power is turned on, and during this time, the operational amplifier I Cs
The output of is set to the above-mentioned value, and with the operating frequency determined by this, the discharge lamp on the installed side of the discharge lamps D L I and D R2 is preheated in advance. After that, when both transistors T r 2 + T r * are turned off, the non-inverting input terminal voltage of the operational amplifier I Cs increases due to the time constant determined by the resistors R9 to R,,,R,3 and the capacitors C13 and CI4. Accordingly, the operating frequency decreases, the voltage applied to the discharge lamp gradually increases, and finally the discharge lamp is turned on, and the operating frequency of the inverter circuit 2 becomes such that the output voltage of the operational amplifier C5 becomes R + o. This will decrease to a value of V cc/(R9+R+.).

Next, FIG. 4(b) is an explanatory diagram of the operation when the discharge lamps DL, DL2 are both attached. In this case, N
Since the inputs of AND games 1 to G are both at the "'Higl+" level, their outputs are at the "LOLI+" level.

Therefore, the output of the AND gate G3 becomes 'Low' level, and the transistor Tr is turned on for 0.1 seconds after the power is turned on, and then turned off.
．． It will continue to be on for 9 seconds, and the voltage at the 5th terminal of the astable multi-by-break IC at this time will be RB・Vc
c/(Rs+RB) (However, RB=P+o ・R,z/
(R+o+Rz)), and the transistor Tr is driven at an operating frequency corresponding to this value. In this state, 2
When the lamp is installed, the discharge lamp is set so that it will not start (however, when one lamp is installed, the discharge lamp will start), and at this operating frequency, the discharge lamp will not start.
The discharge lamps DLI and DL2 are preheated in advance. After that, when the transistor Tr2 is turned off, the operational amplifier I
The output voltage of Cs gradually increases, and the two discharge lamps DL + and DR2 are started and lit accordingly.

As can be seen from the above description, the monostable multi-hybrator IC works as a pre-warming timer.

In addition, after turning on the monostable multivibrator IC,
Monostable multi-vibration IC with timer lamp installed to detect the number of installed discharge lamps C4
The fixed period set by The operating frequency of the inverter circuit 2 is determined in accordance with the number of discharge lamps installed so that appropriate preheating can be obtained.

Fig. 5 is a circuit diagram of another embodiment of the present invention, and the illustration of the same parts as the circuit of Fig. 2 is omitted. In the embodiment shown in FIG. 5, the preheating time is changed depending on the mounting state of the discharge lamp, thereby properly preheating the discharge lamp regardless of the mounting state of the discharge lamp, and solving the problem of shortening the lamp life. are doing.

In this embodiment, the balancer transformer T is used.

By detecting the induced voltage of
It is determined whether the light is installed or not. If 1 light is installed, 2
Since the current flowing through the balancer transformer T1 becomes unbalanced compared to the case of the lamp installation, the voltage induced in the balancer transformer T1 becomes higher. This induced voltage is charged to capacitor C16 via diode D3. A resistor R+6 is connected in parallel to the capacitor C86. The terminal voltage of the capacitor CI6 is applied to the non-inverting input terminal of the comparator C6. A reference voltage obtained by dividing the power supply voltage Vcc by resistors R17 and R18 is applied to the inverting input terminal of the comparator C6, and this reference voltage is applied to the inverting input terminal of the comparator C6. It is set to be at the 'LOII+' level when two lights are installed.

The glue set terminal (terminal 4) of the monostable multivibrator IC is connected to the power supply voltage Vcc via a resistor R1g. Between the connection point between the resistor Rl 9 and the reset terminal and the ground level, the collectors and emitters of transistors 1 to Tr< are connected.

A comparator C6 is connected to the base of the transistor Tr.
output is connected. Monostable multivibrator I
The outputs of C3 and IC4 are connected to the input of OR gate G5. The output of OR gate G5 is connected to the base of transistor T r 2 via resistor R12. The other circuit configurations are the same as the circuit in FIG. 2.

Monostable multivibrator IC, transistor Tr<
When is off, its output (terminal 3) remains active for a certain period of time after the power is turned on, similar to the monostable multivibrator IC3.
It operates as a timer in which the IC becomes "Higb" level, but the period in which it becomes "Hi 8h" level is set to be longer than that of the monostable multi-by-break IC3.

FIG. 6(a) is an explanatory diagram of the operation of this embodiment when the power is turned on with one lamp installed. In this case, the level of the non-inverting input is higher than that of the inverting input, and the output of the comparator C6 becomes 'Higl+' level, so the transistor Tr
, turns on. When transistor Tr4 turns on,
The glue set terminal (terminal 4) of the monostable multi-vibrator IC1 becomes 'L oul' level, and the output of the monostable multivibrator IC is forced to become 'Lou+' level. Therefore, the transistor Tr2 is turned on via the OR gate G only when the output of the monostable multivibrator IC3 is at the "High" level, and the output voltage of the operational amplifier IC5 at this time is Re-V(IC
/(R9+RC)C However, Rc = R+ o R+
+ (R+ o + R+ + )], and the discharge lamp is preheated at the operating frequency determined by the output voltage of the operational amplifier C5. When transistor Trz turns off,
The output voltage of the operational amplifier C5 gradually increases, and finally reaches R10・V cc/ (Ra + R1°).As the output voltage of the operational amplifier C5 increases, the voltage applied to the discharge lamp gradually decreases. The discharge lamp is started and lit.

FIG. 6(b) is an explanatory diagram of the operation of this embodiment when the power is turned on with two lamps installed. In this case, the comparator ■
Since the output of C6 is at the 'Loud' level, the transistor Tr4 is turned off, and therefore the monostable multivibrator IC performs a timer operation, but during the period when the output of the monostable multivibrator IC is at the 'High' level, Since the on-period of transistor Tr2 is determined by the output of the monostable multi-bi break IC, the preheating time is set longer than that of the monostable multi-bi break IC. It is.

Note that the output voltage of the operational amplifier IC5 is Re・Vcc/
At the operating frequency of (Rg + Rc), the installed discharge lamp is set so that it will not be subjected to cold cathode discharge regardless of the installation status of the discharge lamp. This is the operating frequency at which cold cathode discharge does not occur. The reason for this is that when two discharge lamps are installed, in most cases, one discharge lamp starts first, which generates high voltage in the balancer transformer T1, causing the other discharge lamp to start. This is because the discharge lamp is started. In other words, first one lamp lights up, and then two lamps turn on. This means that it is easier to start with one lamp installed, that is, if operation is performed under the same frequency, one lamp will turn on. This means that the voltage applied to the lamp is higher when the lamp is attached.

FIG. 7 is a circuit diagram of still another embodiment of the present invention, and the illustration of the same parts as the circuit of FIG. 2 is omitted. In this embodiment, discharge lamps with different lamp ratings are lit in parallel. Due to different lamp ratings,
The startability when one lamp is installed differs depending on which discharge lamp DL or DL2 is installed. Therefore, in this case, if only the discharge lamp DL+ is installed, if only the discharge lamp DL2 is installed,
When the discharge lamps DL, DL2 are both installed, it is necessary to perform appropriate advance preheating in each case. The advance preheating timer 7 is a monostable multi-vibration IC in the circuit shown in FIG.

This corresponds to

When the discharge lamps DL, DL2 are attached, the terminal voltages of the capacitors C, 5, and C+S become high, respectively. Each terminal voltage is connected to two inputs of AND gate G6 and to one input of AND gates G s and G s. The output of the AND gate G6 is inverted by an inverter G7 and input to the other inputs of the AND gates Ga and Gs. AND GATE G6, G6. The output of G9 is an AND gate G, respectively. .

It is connected to one input of GI I + G l 2. The output of the advance preheating timer 7 is connected to the other input of the AND gate G,o,G,...,G,2. The output of AND gate a,,,c,,,G,2 is,
Transistors Tr, rTrs + Tr7 are connected to their bases, respectively, and transistors Tr5. T
When rs and Tr7 are turned on, the respective resistors R21
1R221R2s is connected in parallel to resistor R10.

The operation of this embodiment will be explained below.

First, when two discharge lamps are installed, the output of the AND gate G6 is ')(iFlb' level, therefore the output of the inverter G7 is 'Lou+' level, and the output of the AND gate G s and G9 is 'Lou+' level. The output is ' L 011
1' level.

Therefore, during the preliminary preheating period in which the output of the preliminary preheating timer 7 is at the Hi8h level, the output of the AND gate G1 is at the HiFib level, the transistor Tr5 is turned on, and the outputs of the AND gates G, , G, and 2 are turned on. is “LO”
LI+”Level, transistor T r 6. T r
7 is off.

Next, when only the discharge lamp DL is attached, a charging voltage is generated in the capacitor C55, and a charging voltage is generated in the capacitor C46.
Since the voltage of is almost zero, AND gate G6.
The output of G9 is "Lo4" level, and gate G8
The output of the AND gate G and 1 is at the ") (i gh" level), and during the advance preheating period, only the output of the AND gates G and 1 is "'High".
''' level, and only the transistor Tr6 is turned on.

Furthermore, if only the discharge lamp DL2 is installed,
Similarly, only the transistor Tr is turned on.

Therefore, depending on the mounting state of the discharge lamp, only one of the transistors Tr5 to Tr is turned on during the advance preheating period, so for each of the above three mounting states,
Appropriate preheating is performed, and the discharge lamp can be started and lit.

Kanse5+I4- FIG. 8 is a circuit diagram of another embodiment of the present invention.

As before, the illustration of the same parts as the circuit of FIG. 2 is omitted. In this example, three discharge lamps D L
This is an example in which T + , D L 2 , and D L 3 are lit in parallel via balancer transformers T + and T 2 . In this case as well, it is considered that cases where the lighting timing is the same no matter which two lamps are selected almost never occur, so if only one of the three discharge lamps is installed, two If only the light is installed,
The discharge lamps are easier to start in the order in which all three lamps are installed, that is, compared to the case in which they operate under the same frequency, the applied voltage to the discharge lamps is higher in the above order. Conceivable. Therefore, if the operating frequency during preheating is set to be the highest when only one lamp is installed and the lowest when all three lamps are installed, the discharge lamp can be discharged. Appropriate preheating can be performed regardless of the installed state of the electric light.

In this embodiment, a current transformer CT3 is provided at the end of the discharge lamp DL3 in order to detect the attachment of the third discharge lamp DL. The output of current transformer CT3 is charged to capacitor CI9 via diode D. A resistor R19 is connected in parallel to the capacitor C2. Discharge lamps DL,, DL2. When DL3 is installed, the voltages of capacitors CIs + CI 61 and CI 9 rise, respectively, and the voltages of inverters Gl, ], Gz.

When the threshold voltage of G15 is exceeded, the inverter G
l 31 G 141 G + 5 output is "Lo field"
Lebel inverter G, 3, G, . , GH are connected to one input of AND gates G + o, G + 1, and G l 2.

Andgate G. ．． , G, , , G,2 are connected to the output of the advance preheating timer 7 to the other input. The outputs of Antoge-1% Q, o, G, , G, 2 are the transistors T r s , T r 6 , T r ? are connected to the bases of the transistors T r s
+ When T r s + T r 7 is turned on, the respective resistances R 2 1 1 R 2 2 1 R
2 3 is the resistance R 1 .

are connected in parallel. The output of the advance preheating timer 7 is also connected to the base of the transistor TrlI, and when this transistor Tra is turned on, the resistor R24 is connected in parallel to the resistor RIO.

Therefore, the output of the advance preheating timer 7 is "High".
During the advance preheating period when the level is 1, the transistor Tr5 is turned on unconditionally. On the other hand, discharge lamps DL,~D
If L3 is installed, the corresponding inverter G
Considering that the output of 13 to G+5 will be at the 'Lou+' level, when only one lamp is installed, the transistor Tr5
Two of the transistors Tr7 are turned on, one of the transistors Tr5 to Tr7 is turned on when two lamps are installed, and all of the transistors Tr5 to Trt are turned off when three lamps are installed. Therefore, the values of resistors R21 to R23 are set to R2 + -
R2□-R. If you select 23=R, the resistance will be R, when only one light is installed. In parallel with R2, a parallel resistor of R/2 will be connected during the pre-warming period. Also,
When only two lamps are installed, the resistor R14 and the resistor R are connected in parallel to the resistor R1o, and when three lamps are installed, the resistor R14 is connected in parallel to the resistor R1o. Therefore, the output voltage of the operational amplifier IC5 during the advance preheating period is lowered in the order of 1 lamp, 2 lamps, and 3 lamps installed, thereby increasing the operating frequency of the inverter circuit. , Appropriate preheating can be performed depending on the number of discharge lamps installed.

FIG. 9 is a circuit diagram of still another embodiment of the present invention. In this embodiment, a preliminary preheating timer that fixes the operating frequency for a certain period of time during the preheating period is not provided, and after the power is turned on, the lamp voltage is gradually increased from a voltage at which the discharge lamp does not discharge cold cathode. This is a so-called soft start circuit that starts and lights up the discharge lamp, and by changing the degree of increase in the voltage applied to the lamp during the start period to the software 1 according to the number of discharge lamps installed,
Appropriate advance preheating is performed according to the number of lights installed.

In this embodiment, as in the circuit of FIG. 5 (Embodiment 2), the mounting state of the discharge lamp is determined by detecting the voltage of the balancer transformer T1. The obtained reference voltage of the comparator ICs is the non-inverting input terminal voltage.

That is, in this example, when two lights are installed, comparator I
The output of C, becomes 'H'high' level, and when one lamp is installed, the output of comparator IC6 becomes 'Loud' level. The output of comparator IC6 becomes 'Loud' level.
connected to the base of the rg. When the transistor Trs is turned on, the capacitor C2□
2+ in parallel. A diode D for ensuring a discharge path for the capacitor C22 is connected in antiparallel to the transistor Tr9.

Power supply voltage Vcc is applied to the series circuit of capacitor C2, resistor R9, and RIO. Resistor R3 and Resistor R3
This connection point is connected to the non-inverting input terminal of the operational amplifier ICS, and the output voltage of this operational amplifier C5 serves as a control signal for soft start.

The operation of this embodiment will be explained below.

FIG. 10(a) is an explanatory diagram of the operation of this embodiment when one lamp is attached. When one lamp is installed, the terminal voltage of the capacitor CI6 becomes high, so the inverting input of the comparator IC6 becomes higher than the non-inverting input, and the output of the comparator IC becomes the "Lou+'" level. Therefore, transistor Tr9 is turned off, and capacitor C2□ is separated from capacitor C21.

Due to this, the voltage of capacitor C21 quickly rises,
Since the output voltage of operational amplifier IC3 also rises quickly,
The soft start period will be shorter.

FIG. 10(b) is an explanatory diagram of the operation of this embodiment when two lights are installed. When two lamps are installed, the terminal voltage of the capacitor CI6 becomes low, so the inverting input of the comparator IC6 becomes lower than the non-inverting input, and the output of the comparator Ice becomes "High" level. Therefore, the transistor Tr) is turned on, and the capacitor C22 is connected in parallel with the capacitor C21, so the output voltage of the operational amplifier C5 gradually increases compared to when one lamp is installed, and the soft start period is become longer. That is,
When two lamps are installed, compared to when one lamp is installed, it takes longer to shift to the operating frequency at which a discharge starting voltage can be obtained, and as a result, appropriate preheating can be performed according to the number of installed lamps.

Note that any separately excited inverter circuit may be used as the discharge lamp lighting device, and its configuration is such that multiple discharge lamps are lit in parallel, and the vibration frequency of the load during preheating is adjusted according to the mounting state of the discharge lamps. There is no particular limitation as long as it changes.

(Effects of the Invention) According to the present invention, appropriate preliminary preheating can be obtained according to the number of discharge lamps installed, so that the discharge lamps can be heated regardless of the number of installed discharge lamps. It is a device that can ensure the lamp life, for example, a discharge lamp lighting device for two lamps can be
Even when the lamp is used with two lamps installed, the lamp life is not significantly impaired compared to when two lamps are installed.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram for explaining the basic configuration of the present invention, FIG. 2 is a circuit diagram of an embodiment of the present invention, and FIGS. 3 and 4 (a) and (b) are explanations of the operation of the same. 5 is a circuit diagram of another embodiment of the present invention, FIGS. 6(a) and 6(b) are operation explanatory diagrams of the same as above, and FIG. 7 is a circuit diagram of still another embodiment of the present invention. FIG. 8 is a circuit diagram of another embodiment of the present invention, FIG. 9 is a circuit diagram of still another embodiment of the present invention, and FIG. 10 (aHb)
is an explanatory diagram of the same operation as above, Fig. 11 is a circuit diagram of the conventional example, and Fig.
FIG. 2 is an explanatory diagram of the same operation. DL, DL2 is a discharge lamp, E is a DC power supply, 2 is a separately excited inverter circuit, 3 is a control circuit, 4 is a preheating state determination circuit,
5 is a lamp number discrimination circuit.

Claims (2)

[Claims] (1) A DC power supply, a high frequency conversion circuit that converts the output of this DC power supply into high frequency, a plurality of discharge lamps connected in parallel to the output terminal of this high frequency conversion circuit, and an increase in the voltage applied to the discharge lamps. In a discharge lamp lighting device that has a preheating circuit that increases the filament current of the discharge lamp, and the vibration frequency of the load is determined by the high frequency conversion circuit, the discharge lamp, and the preheating circuit, the installed normal 1. A discharge lamp lighting device comprising a control means for controlling a high frequency conversion circuit so that each discharge lamp is properly preheated according to the number of discharge lamps. (2) The discharge lamp lighting device according to claim 1, wherein the high frequency conversion circuit is a separately excited inverter circuit.