JPH0636297U - Starting circuit for vehicle discharge lamp - Google Patents

Abstract

(57) [Summary] [Purpose] To ensure reliable startup of the vehicle discharge lamp when it is turned on again. [Structure] In the igniter circuit 8 of the metal halide lamp 10, the primary winding side circuit of the trigger transformer 18 is connected in series with a series circuit including a primary winding 18a, an inductor 29, a spark gap element 28, and a capacitor 27. It is composed of a capacitor 30. When the terminal voltage of the capacitor 27 rises to a predetermined voltage and the spark gap element 28 becomes conductive, the primary winding 18a of the transformer 18 is not immediately applied with a voltage, and a start pulse is generated with a time corresponding to a certain discharge start voltage. To stand up.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention, in a starting circuit for a vehicle discharge lamp, which is configured to start the discharge lamp by a high-voltage pulse at the time of starting the discharge lamp, can ensure the reliability of the starting when the lamp is re-lighted. It is intended to provide a new starting circuit for a vehicle discharge lamp.

[0002]

[Prior art]

 Recently, small metal halide lamps have been receiving attention as a light source to replace incandescent light bulbs.As a lighting method for metal halide lamps for vehicles, a DC input voltage is boosted by a booster circuit, and then a rectangular wave or There is known an AC lighting method in which the voltage is converted into a sine wave AC voltage and then applied to an AC specification metal halide lamp.

At this time, a high voltage of several kV to several tens of kV is required to turn on the lamp.

FIG. 7 shows a configuration example a of the starting circuit.

A DC-AC conversion circuit (not shown) is provided in the preceding stage of this starting circuit, and an AC voltage is supplied to the metal halide lamp d 1 via the secondary winding c of the trigger transformer b on the power supply line. It is like this.

In the series circuit composed of the capacitor e, the spark gap element f, and the primary winding g of the trigger transformer b, when the terminal voltage of the capacitor e reaches a predetermined voltage when the lamp is started, the spark gap element f is The pulse is generated, and the pulse generated at this time is boosted by the trigger transformer b and applied to the metal halide lamp d, whereby the lamp is activated.

[0007]

[Problems to be solved by the device]

 However, in the above-mentioned starting circuit a, when the metal halide lamp d is turned on again after it is turned off, there is a problem in that arc discharge may not occur even if the lamp is started by a starting pulse.

This is because the discharge start voltage changes depending on the degree of rising of the start pulse, and the discharge start voltage becomes higher as the pulse rises more rapidly.

FIG. 8 shows a temporal change of the starting pulse voltage v, and the starting point of time is when the spark gap element f is in conduction.

In the above-mentioned circuit, as shown in the figure, the start-up pulse rapidly rises with the conduction of the spark gap element f, and then causes LC resonance accompanied by damping oscillation.

As shown in FIG. 9, the equivalent circuit h of the primary side circuit of the trigger transformer b is a capacitor e, an inductive load component Lg of the primary winding g, and a resistive load component Rg of the primary winding g. , A spark gap element f (indicated by a switch symbol in the figure), and the transient response characteristic makes the rise time of the voltage v theoretically zero.

[0012] Therefore, when the metal halide lamp is turned off and then turned on again without a time interval, the discharge starting voltage becomes high and the starting uncertainty is accompanied.

Therefore, there is known a method of shifting from glow discharge to arc discharge by superimposing a sine wave voltage of about 1 kV on the output before and after starting the lamp, or by giving the lamp a pulse of a predetermined width immediately after the starting pulse. However, this involves the intricacies of the circuit structure, resulting in an increase in the size of the lighting unit.

[0014]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the starting circuit for a vehicle discharge lamp according to the present invention generates a pulse by the conduction of a switching element when the terminal voltage of the first capacitor exceeds a predetermined value. In a starting circuit for a vehicle discharge lamp in which this is boosted through a transformer and then sent to the discharge lamp as a starting pulse, an inductor is provided in series with a switching element, and the first capacitor and the transformer A series circuit including a primary winding, an inductor, and a switching element is formed, and a second capacitor is provided in parallel with the series circuit.

[0015]

[Action]

 According to the starting circuit of the vehicle discharge lamp of the present invention, an inductor is connected in series to the primary winding of the transformer in the primary circuit of the starting circuit for generating the starting pulse of the discharge lamp, and a capacitor is provided in parallel with the inductor. As a result, the start-up pulse rises slowly, and the start-up operation can be performed reliably because the start-up operation can be performed with the discharge start voltage being low when the discharge lamp is turned on again after it is turned off. There is no complicated circuit configuration.

[0016]

【Example】

 Hereinafter, a starting circuit of a vehicle discharge lamp according to the present invention will be described in detail with reference to the illustrated embodiment.

FIG. 2 shows an outline of the lighting circuit 1, in which the battery 2 is connected between the DC voltage input terminals 3 and 3 ′.

Reference numerals 4 and 4 ′ are DC power supply lines, and a lighting switch 5 is provided on one of the plus lines 4.

A DC boosting circuit 6 is provided for boosting the battery voltage, and the boosting control is performed by a control circuit described later.

Reference numeral 7 denotes a DC-AC conversion circuit, which is provided at a subsequent stage of the DC boosting circuit 6 and converts a DC voltage sent from the DC boosting circuit 6 into a rectangular wave AC voltage. For the DC-AC conversion circuit 7, for example, a bridge type drive circuit is used.

Reference numeral 8 denotes an igniter circuit, which is arranged at the subsequent stage of the DC-AC conversion circuit 7, and a metal halide lamp 10 having a rated power of 35 W is connected between the AC output terminals 9 and 9 '.

Reference numeral 11 is a control circuit for controlling the output voltage of the DC boost circuit 6, and the output voltage of the DC boost circuit 6 detected by the voltage detection unit 12 provided between the output terminals of the DC boost circuit 6. Detection signal is input.

In addition, the current detection signal corresponding to the output current of the DC booster circuit 6 is converted into a voltage by the current detection unit 13 provided on the line connecting the DC booster circuit 6 and the DC-AC converter circuit 7. Is input to the control circuit 11.

Then, the control circuit 11 generates control signals according to these detection signals and sends them to the DC booster circuit 6, and controls the output voltage thereof to obtain the power corresponding to the state when the metal halide lamp 10 is started. The control is designed to shorten the starting time and restarting time of the lamp and to perform stable lighting control during steady state.

The control circuit 11 has a V (voltage) -I (current) controller 14 and a PWM (pulse width modulation) controller 15.

The VI controller 14 is configured to perform lighting control of the metal halide lamp 10 based on a control curve that defines the relationship between the lamp voltage and the lamp current, and relates to the output voltage of the DC booster circuit 6. When the detection signal is sent from the voltage detection unit 12, a current command value according to the detection signal is calculated and the command signal is sent to the PWM control unit 15.

The VI controller 14 also sends a signal to the PWM controller 15 for limiting the lamp current in the initial stage of lighting so that the lamp current does not become an excessively large value.

The PWM control unit 15 generates a signal whose pulse width is variable according to the command signal from the VI control unit 14, and uses this as a control signal for the semiconductor switch element in the DC booster circuit 6. It is designed to be sent out.

FIG. 1 shows a configuration example of the igniter circuit 8.

Reference numerals 16 and 16 ′ are output terminals of the DC-AC conversion circuit 7, and a secondary winding 18 b of a trigger transformer 18 is provided on a power supply line 17 connecting the output terminal 16 and the AC output terminal 9. .

The power supply line 17 'is a line connecting the output terminal 16' and the AC output terminal 9 '.

The resistor 19 has one end connected to the output terminal 16 and the other end connected to the output terminal 16 ′ via the capacitor 20 and the diode 21.

Reference numeral 22 denotes a diode, the anode of which is connected between the capacitor 20 and the diode 21 and the cathode of which is connected to the starting end side terminal of the primary winding 24 a of the transformer 24 via the capacitor 23.

Reference numeral 25 denotes an SSS (Silicon Symmetrical Switch), one end of which is connected to the cathode of the diode 22 and the other end of which is connected to the power supply line 17 ′.

In the transformer 24, the terminal of the secondary winding 24 b on the terminal side is connected to the terminal of the primary winding 18 a of the trigger transformer 18 via the diode 26 and also connected to one end of the capacitor 27. In addition, the starting end side terminal of the secondary winding 24b is connected to the feeding line 17 '.

Reference numeral 28 is a spark gap element, one end of which is connected to the starting end side terminal of the primary winding 18a of the trigger transformer 18 via the inductor 29, and the other end of which is connected to the power feeding line 17 '.

A capacitor 30 is provided in parallel with the spark gap element 28 and the inductor 29.

In the igniter circuit 8, the output voltage of the DC-AC conversion circuit 7 is rectified by double voltage and then boosted by the transformer 24 to charge the capacitor 27. When this exceeds a predetermined voltage, the spark gap is exceeded. The pulse generated by the conduction of the element 28 is boosted by the trigger transformer 18 and sent to the metal halide lamp 10.

FIG. 3 shows an equivalent circuit 31 of the primary side circuit of the trigger transformer 18.

In the figure, L18 indicates the inductance of the primary winding 18a of the trigger transformer 18, R18 indicates the resistance of the primary winding 18a of the trigger transformer 18, L29 indicates the inductance of the inductor 29, and R29 indicates the inductance of the inductor 29. The resistance components are shown respectively, and the spark gap element 28 is represented by a switch symbol SW (28).

Further, C27 and C30 represent the electrostatic capacities of the capacitors 27 and 30, respectively.

As shown in the figure, the equivalent circuit 31 has a loop (current is “i”) that passes through C27, L18, R18, L29, R29, and SW (28) by turning on SW (28), and C30 ,. A loop passing through SW (28), R29 and L29 is formed.

When the terminal voltage of C27 is set to E0 and the initial condition of current i = 0 and charge q = C27 · E0 is given to the equivalent circuit 31, the transient response characteristic is examined. It becomes like 4.

As shown by the graph curve 32, the voltage v rises from v = 0 (t = 0) over a period Δt, reaches a peak value (“α · E0”), and then shifts to a damping oscillation. I know what to do.

The average slope value of the rising portion of the graph curve 32 is α · E0 / Δt, and is numerically, for example, about 21 kV / μsec.

FIG. 5 schematically shows the relationship between the discharge start voltage Vs and the time t, and the graph curve 33 shows a decrease with the passage of time.

Therefore, when the rising edge of the starting pulse is steep as shown by the broken line 34 in the figure, the discharge start voltage Vs becomes the voltage value Vs1 at the intersection P1 with the graph curve 32, but the broken line 35 shows As shown, when the rising slope of the starting pulse is gentle, the discharge start voltage Vs becomes the voltage value Vs2 (<Vs1) at the intersection P2 with the graph curve 32.

As described above, by delaying the rising of the starting pulse, the discharge starting voltage Vs becomes small, and the reliability of the starting operation at the time of re-lighting the lamp can be guaranteed, and the withstand voltage design on the element and mounting. Can afford.

In the present embodiment, the two-stage configuration of the transformer is used for generating the starting pulse, but the triple transformer rectification is adopted as in the circuit 36 shown in FIG. 6 so that the first-stage transformer is omitted. Is also good.

In the figure, the capacitor 37 has one end connected to the power supply line 17 and the other end connected to the power supply line 17 ′ via the diode 38 and the resistor 39.

A diode 40, a capacitor 41, and a resistor 42 are provided in parallel with the diode 38 and the resistor 39, and the anode of the diode 43 is connected to the cathode of the diode 40, the cathode of which is connected to one end of the spark gap element 28. It is connected.

The other end of the spark gap element 28 is connected to the power supply line 17 via the inductor 29.

One end of the capacitor 27 is connected to the starting end side terminal of the secondary winding 18 b of the trigger transformer 18 and the ending end side terminal of the primary winding 18 a, and the other end is connected to the cathode of the diode 43. .

One end of the capacitor 30 is connected to the starting end side terminal of the primary winding 18 a of the trigger transformer 18, and the other end is connected to the cathode of the diode 43.

It should be noted from the configuration that the equivalent circuit of the primary side circuit of the trigger transformer 18 has the same configuration as in FIG.

[0056]

[Effect of device]

 As apparent from the above description, according to the present invention, when the terminal voltage of the first capacitor exceeds a predetermined value and the switch element becomes conductive, the voltage is immediately applied to the primary winding of the transformer. Not surprisingly, the resonance of the primary winding of the transformer, the inductor, and the first and second capacitors slows the startup pulse of the discharge lamp, and the discharge start voltage is low when the discharge lamp is turned on again. Since the startup can be performed in this state, the reliability of the startup operation can be ensured.

Moreover, for that purpose, it is not necessary to superimpose a sine wave or a pulse of a predetermined width on the output, and it suffices to add passive elements such as an inductor and a capacitor, so that the circuit configuration becomes complicated and the cost increases accordingly. In addition, since the discharge start voltage at the time of relighting can be lowered, the breakdown voltage design becomes easy.

In the above-mentioned embodiment, the example in which the present invention is applied to the lighting circuit of the rectangular wave lighting system is shown, but the present invention is not limited to this and can be applied to various lighting circuits of the sine wave lighting system and the like. Of course.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration example of a starting circuit of a vehicle discharge lamp of the present invention.

FIG. 2 is a circuit block diagram showing a configuration example of a lighting circuit to which the present invention is applied.

FIG. 3 is an equivalent circuit diagram of a main part.

FIG. 4 is a graph showing a temporal change of a starting pulse according to the present invention.

FIG. 5 is a graph showing the relationship between discharge start voltage and time.

FIG. 6 is a circuit diagram showing a modified example of the present invention.

FIG. 7 is a diagram showing a conventional circuit configuration.

FIG. 8 is a graph showing a change over time of a conventional starting pulse.

FIG. 9 is an equivalent circuit diagram of a primary side circuit of a trigger transformer in a conventional example.

[Explanation of symbols]

 8 Vehicle Discharge Lamp Starting Circuit 10 Discharge Lamp 18 Transformer 18a Primary Winding 27 First Condenser 28 Switching Element 29 Inductor 30 Second Capacitor 36 Vehicle Discharge Lamp Starting Circuit

Claims (1)

[Scope of utility model registration request] 1. A pulse is generated by conducting a switching element when a terminal voltage of a first capacitor exceeds a predetermined value, and the pulse is boosted via a transformer and then sent to a discharge lamp as a start pulse. In the starting circuit for a vehicle discharge lamp, the inductor is provided in series with the switching element to form a series circuit including the first capacitor, the primary winding of the transformer, the inductor, and the switching element, and A starting circuit for a vehicle discharge lamp, wherein a second capacitor is provided in parallel with a series circuit.