JP4391199B2 - Discharge lamp lighting device - Google Patents

Description

  The present invention relates to a discharge lamp lighting device for lighting a high-intensity discharge lamp (HID bulb) used as a headlamp, an illumination lamp, a street lamp, or the like of an automobile.

  Conventionally, a discharge lamp lighting device for lighting a high-intensity discharge lamp such as a metal halide lamp uses an igniter (starting device) composed of a high-voltage pulse voltage generation circuit, and when a switch element such as a discharge gap or a thyristor is turned on, The electric charge charged in the charging capacitor is discharged through the path including the switching element and the primary winding of the high voltage pulse transformer, and the high voltage pulse voltage generated in the secondary winding of the high voltage pulse transformer is applied to the high intensity discharge lamp. Thus, breakdown (insulation breakdown) is caused in the tube of the high-intensity discharge lamp to shift to arc discharge (see, for example, Patent Document 1).

JP-A-10-125482

  Conventional discharge lamp lighting devices are configured as described above, and high-intensity discharge lamps such as metal halide lamps are used as light sources for projectors and in-vehicle headlamps. When using a discharge lamp, the power supply is frequently turned on and off in a short time. After turning off the high-intensity discharge lamp that has been lit, do not wait too long (the high-intensity discharge lamp remains hot). It is necessary to start it up reliably even in the hot start that relights.

  In high-intensity discharge lamps such as metal halide lamps, the equivalent resistance after breakdown by applying a high-pressure pulse during hot start is larger than the equivalent resistance at the start-up due to the gas state inside the discharge lamp. If sufficient energy cannot be supplied, there is a problem in that even if breakdown occurs, stable arc discharge cannot be entered and restarting fails. For this reason, in order to use a high-intensity discharge lamp such as a metal halide lamp for the above-described applications, it is necessary to supply sufficient energy immediately after the breakdown. As a countermeasure, the capacitance of the charging capacitor has been increased. However, the increase in inrush current flowing through the switch element increases the burden on the switch element, and there is a concern that the switch element may be destroyed or its life may be reduced. The Therefore, when the capacitance of the capacitor is increased in the conventional device, it is necessary to suppress the burden on the switch element. As a countermeasure, if the number of switch elements is increased or the switch element is changed to a larger switch element, the igniter There were problems such as an increase in size.

  The present invention has been made to solve the above-described problems, eliminates the extinction due to insufficient energy after the breakdown of the discharge lamp, and is sufficient to suppress an increase in the load on the switch element. An object is to obtain an inexpensive discharge lamp lighting device by simplifying a configuration capable of supplying energy.

A discharge lamp lighting device according to the present invention includes a power supply voltage generation means for generating a power supply voltage for discharge lamp lighting based on an output of a DC power supply, and stores energy based on the power supply voltage from the power supply voltage generation means for lighting. A discharge lamp lighting device comprising high voltage pulse generating means for supplying a high voltage pulse for breaking down between the electrodes of the discharge lamp at the start, wherein the high voltage pulse generating means includes a breakdown between the electrodes of the discharge lamp. When a high voltage is applied to shift to glow discharge , a small amount of energy is supplied to the discharge lamp. When a low voltage is applied, the discharge between the electrodes of the discharge lamp is shifted from glow discharge to arc discharge, the energy is increased to release the discharge. An energy supply means for supplying to the electric lamp is provided, and this energy supply means turns on the switch element provided in the primary side connection path of the high-voltage generating pulse transformer. It is supplied to the discharge lamp small energy of the high voltage charged when, and wherein the energy is a capacitor which has the property of increasing the energy supplied to the discharge lamp in accordance with the voltage drop due to release.

  The present invention supplies a high voltage and small energy at the time of glow discharge when the discharge lamp is broken down, and supplies low voltage and large energy at the time of transition from glow discharge to arc discharge. ) Can be improved with certainty, and the light extinction due to lack of energy after the dielectric breakdown of the discharge lamp can be eliminated, and the increase of the load on the switch element can be suppressed to prevent the switch element from being destroyed and the service life from being shortened.

Embodiment 1 FIG.
An embodiment of the present invention will be described below.
1 is a circuit diagram showing a configuration of a discharge lamp lighting device according to Embodiment 1 of the present invention.
In FIG. 1, a discharge lamp lighting device according to the present embodiment includes a DC power source 1, a lighting switch 2, a DC / DC converter 3 as a power source voltage generating unit, an inverter 4, a control unit 5, and an energy supplying unit. And a discharge lamp 7 which is a high-intensity discharge lamp (HID bulb). The igniter 6 includes a voltage dividing resistor 61 and a voltage dividing resistor 62 that also serve as charging resistors, a charging resistor 63, a discharging capacitor 64, a discharging capacitor 65, a backflow preventing diode 66, a switch element 67, And a high-voltage pulse transformer 68.

  The DC power source 1 is made of a battery, for example, and outputs a DC voltage of 12V. A DC power source 1 is connected to a DC / DC converter 3 via a lighting switch 2, and an inverter 4 is connected to an output side of the DC / DC converter 3, and both the DC / DC converter 3 and the inverter 4 control their operations. 5 is controlled. The DC / DC converter 3 steps down or boosts the voltage of the direct current power source 1 to a voltage necessary for starting and lighting the discharge lamp 7 connected to the output side of the inverter 4 via the secondary side of the high voltage pulse transformer 68. In addition, the inverter 4 converts the DC voltage that is the output of the DC / DC converter 3 into an AC voltage and supplies the AC voltage to the discharge lamp 7.

  Voltage dividing resistors 61 and 62 are connected in series between the output side of the DC / DC converter 3 and one end of the output side of the inverter 4 (the side to which one end of the primary winding of the high voltage pulse transformer 68 is connected). Discharge capacitors 64 are connected in parallel across the resistor 62. A charging resistor 63 and a discharging capacitor 65 are connected in series between one end of the output side of the DC / DC converter 3 and the output side of the inverter 4. A switch element 67 is connected between the connection point of the charging resistor 63 and the discharging capacitor 65 and the primary winding of the high-voltage pulse transformer 68, and the connection point of the voltage dividing resistor (charging resistor) 61 and the discharging capacitor 64 and the switch. A backflow preventing diode 66 is connected between one end of the element 67, that is, between the connection point of the charging resistor 63 and the discharging capacitor 65.

Next, the operation will be described with reference to the characteristic diagrams of FIGS.
Now, when the lighting switch 2 is turned on and the voltage of the DC power supply 1 is boosted by the DC / DC converter 3 and supplied to the igniter 6, the discharging capacitors 64 and 65 are charged through the charging resistors 61 and 63, respectively. Is done. When the switch element 67 is turned on (or spontaneously turned on) when the discharge capacitors 64 and 65 are charged, first, the discharge capacitor 65 having a high potential is discharged, and the current is primary of the high-voltage pulse transformer 68. As a result, a high voltage is generated on the secondary winding side to break down between the electrodes of the discharge lamp 7 to generate glow discharge.

  When the discharge capacitor 65 is discharged and its potential becomes lower than the potential of the discharge capacitor 64, the discharge capacitor 64 starts discharging, and current flows through the primary winding of the high-voltage pulse transformer 68 through the diode 66. In this case, the discharge current flows through both the discharge capacitors 64 and 65, transitions to arc discharge, and thereafter, stable lighting is maintained at the output voltage from the inverter 4.

  FIG. 2 shows the relationship between the capacitances of the discharge capacitors 64 and 65 and the discharge voltage in the above-described operation stage, and the time of the discharge voltage V1 substantially represents the boundary between the high voltage and the low voltage. This indicates that the high voltage depends on the discharge capacitor 65 and the low voltage when the switch element 67 is turned on depends on the discharge capacitors 64 and 65.

  FIG. 3 shows the current I1 flowing through the switch element 67 in the present embodiment in comparison with the current I2 flowing through the switch element according to the conventional configuration. At a high voltage immediately after the switch element is turned on, the current I1 flowing through the switch element 67 in this embodiment is smaller than the current I2 flowing through the switch element in the conventional configuration, but the switch element is turned on. At the time of low voltage after a lapse of time, the current I1 flowing through the switch element 67 in the present embodiment is larger than the current I2 flowing through the switch element in the conventional configuration, Large energy supply is possible compared with the conventional configuration. In other words, according to the present embodiment, energy is not required so much, and the energy between the electrodes of the discharge lamp 7 is suppressed by suppressing the energy at the time of a high voltage that breaks down the electrodes of the discharge lamp 7 and generates glow discharge. Sufficient energy can be supplied at low voltage where energy is required to shift from discharge to arc discharge.

  Therefore, since the energization time of a large current is shortened by suppressing the energy at high voltage, the burden on the switch element 67 can be reduced, and the life of the switch element 67 can be prevented from being destroyed. In addition, by securing energy at low voltage, a small current can flow for a long time, the electrodes of the discharge lamp 7 are heated, and it is easy to shift from glow discharge to arc discharge. improves.

As described above, according to the first embodiment, a high voltage and a small energy are supplied at the time of glow discharge when the HID bulb is broken down, and a low voltage and a large energy are supplied at the time of transition from the glow discharge to the arc discharge. As the energy supply means, for example, by providing a plurality of discharge capacitors in the igniter, it is possible to improve the life of the switch element, the start-up reliability, and the like.
In the above description, the number of discharge capacitors provided in the igniter is two. However, the present invention is not limited to this, and a configuration in which more discharge capacitors are provided according to the specifications of the discharge lamp may be employed. .

Embodiment 2. FIG.
FIG. 4 is a circuit diagram showing a configuration of a discharge lamp lighting device according to Embodiment 2 of the present invention. In FIG. 4, parts corresponding to those in FIG.
In the first embodiment, a plurality of discharge capacitors are provided in the igniter. However, in the present embodiment, as shown in FIG. A discharging capacitor having a voltage dependency is used in which the capacitance of the capacitor decreases as the charging voltage increases.

  In FIG. 4, the igniter 6 </ b> A includes a discharging capacitor 69 connected in series with the charging resistor 63 in addition to the charging resistor 63, the switch element 67, and the high-voltage pulse transformer 68 similar to the igniter 6 of FIG. 1. As the discharging capacitor 69, for example, a ceramic capacitor having such a characteristic that its capacitance decreases depending on the voltage as shown in FIG. Other configurations are the same as those in FIG.

Next, the operation will be described with reference to the characteristic diagram of FIG.
Now, when the lighting switch 2 is turned on and the voltage of the DC power supply 1 is boosted by the DC / DC converter 3 and supplied to the igniter 6 </ b> A, the discharging capacitor 69 is charged via the charging resistor 63. In this case, as the charging voltage of the discharging capacitor 69 increases, the capacitance decreases as shown in FIG. 5, but the switch element 67 is turned on when the charging voltage of the discharging capacitor 69 reaches a predetermined value. When it is turned on (or turned on spontaneously), the discharge capacitor 69 is discharged, and the current flows through the primary winding of the high-voltage pulse transformer 68, whereby a high voltage is generated on the secondary winding side and the discharge lamp 7 is broken down to generate glow discharge, and then the process shifts to arc discharge to stably light up.

Thus, also in the present embodiment, as in the first embodiment, the energy is suppressed at the time of a high voltage that requires less energy and breaks down between the electrodes of the discharge lamp 7 to generate glow discharge. Sufficient energy can be supplied at low voltage when energy is required to shift the discharge between the electrodes from glow discharge to arc discharge.

As described above, in the second embodiment, the discharge capacitor having the voltage dependency in which the capacitance of the capacitor decreases as the charging voltage increases in the igniter is used. In this embodiment, the internal configuration of the igniter can be simplified, and the apparatus can be downsized and the cost can be reduced.
In the above description, the case of a ceramic capacitor is described as an example of a voltage-dependent discharge capacitor in which the capacitance of the capacitor decreases as the charging voltage increases. Other elements may be used as long as the above effect can be obtained.

It is a circuit diagram which shows the structure of the discharge lamp lighting device by Embodiment 1 of this invention. It is a figure for using for operation | movement description of the discharge lamp lighting device by Embodiment 1 of this invention. It is a figure for using for operation | movement description of the discharge lamp lighting device by Embodiment 1 of this invention. It is a circuit diagram which shows the structure of the discharge lamp lighting device by Embodiment 2 of this invention. It is a figure for providing operation | movement description of the discharge lamp lighting device by Embodiment 2 of this invention.

Explanation of symbols

  1 DC power supply, 2 lighting switch, 3 DC / DC converter (power supply voltage generating means), 4 inverter, 5 control unit, 6,6A igniter (energy supply means), 61 voltage dividing resistor (charging resistor), 62 voltage dividing resistor 63, charging resistor, 64, 65, 69 discharging capacitor, 66 diode, 67 switch element, 68 high voltage pulse transformer.

Claims (2)

A power supply voltage generating means for generating a power supply voltage for lighting the discharge lamp based on the output of the DC power supply, and storing energy based on the power supply voltage from the power supply voltage generating means, and a breakdown between the electrodes of the discharge lamp at the start of lighting A discharge lamp lighting device comprising high voltage pulse generating means for supplying a high voltage pulse to be applied to the high voltage pulse generating means at the time of applying a high voltage that breaks down between the electrodes of the discharge lamp and shifts to glow discharge. to supply a small energy to the discharge lamp, the discharge between the electrodes of the discharge lamp when a low voltage is applied to shift from the glow discharge to the arc discharge is to increase the energy with energy supply means for supplying to the discharge lamp, This energy supply means is used to reduce the high voltage charged when the switch element provided in the primary side connection path of the high voltage generating pulse transformer is turned on. Supplying energy to the discharge lamp, the discharge lamp lighting device which is a capacitor having the property of increasing the energy supplied to the discharge lamp in accordance with the voltage drop due to release energy. 2. The ceramic capacitor according to claim 1 , wherein the energy supply means is a ceramic capacitor having a characteristic that the electrostatic capacity decreases as the charging voltage increases and the electrostatic capacity recovers as the voltage decreases due to discharge . Discharge lamp lighting device.

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