JP2007048505A - Discharge lamp lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device capable of controlling lightness and power consumption of a discharge lamp (HID lamp) and stably lighting the discharge lamp. <P>SOLUTION: The discharge lamp lighting device is provided with: a discharge lamp having a pair of electrodes sealed in a discharge tube together with a prescribed gas; a power source part connected to the pair of electrodes in the discharge lamp supplying electric power of a certain level; a capacitor for lighting, storing the electric power output from the power source part, connected to the pair of electrodes of the discharge lamp in parallel through a step-up transformer for lighting; an oscillator generating and outputting a pulse signal having a prescribed frequency; and a preparatory lamp lighting circuit making the electrodes generate preparatory discharge with the frequency of the pulse signal, by impressing a high voltage pulse on the electrodes by receiving the pulse signal generated at the oscillator, and lighting the discharge lamp by inducing a main discharge between the electrodes by the electric power stored in the capacitor for lighting. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a discharge lamp lighting device, and more particularly to a discharge lamp lighting device suitable as a vehicle headlamp.

  Conventionally, an incandescent bulb, which is a light source using temperature radiation generated when a current is passed through a filament, has been used for many years as a vehicle headlamp. In addition, halogen lamps are also applied to vehicle headlights (headlights) because of the demand for headlamps with high luminous efficiency. The halogen lamp has a feature that the filament is lit at a temperature about 200 degrees higher than that of a normal incandescent bulb, and the luminous efficiency is about 10% higher than that of the incandescent bulb, and the lifetime is about twice as long.

  Recently, there has been a demand for a headlight with higher luminance and higher luminous efficiency than a conventional light source using temperature radiation. For example, it is attempted to mount a high-intensity discharge lamp (HID lamp) on a vehicle. (For example, refer to Patent Document 1). This HID lamp uses a discharge generated between a pair of electrodes sealed with gas in the arc tube, and specifically includes a high pressure mercury lamp, a metal halide lamp, a high pressure sodium lamp, and the like. These HID lamps are characterized by higher luminous efficiency and longer life than incandescent bulbs.

When the HID lamp is applied to a vehicle headlamp, generally a direct current extracted from a battery mounted on the vehicle is converted into a high voltage alternating current or direct current by a booster (for example, an inverter) and then applied to the HID lamp. Yes.
Incidentally, when the HID lamp is extinguished due to some influence, it takes time until the HID lamp restarts. For this reason, there is known a vehicle headlight device that substitutes illumination with a separately prepared lamp until it is turned on again for safety reasons (see, for example, Patent Document 2).
JP 2004-322958 A Japanese Patent Laid-Open No. 7-9911

  However, the above-described HID lamp is a light source (lamp) using discharge, and during lighting, the inside of the arc tube is heated by the discharge generated between the electrodes and reaches the maximum luminous intensity in a state where the gas vapor pressure is increased. ing. Further, a lamp using this type of discharge has a concern that the discharge arc of the lamp may be extinguished abnormally due to factors such as deterioration of the lighting device or excessive impact during lighting. In order to relight the HID lamp whose discharge arc has been extinguished, it is necessary to apply a pulse voltage higher than the lamp voltage during lighting or wait until the temperature in the arc tube decreases and the relighting voltage decreases.

  Therefore, in order to apply this type of HID lamp to an automobile headlamp, when the discharge arc of the HID lamp is cut off, a high voltage pulse must be quickly applied to the HID lamp so as to be lit again. Therefore, the power supply unit of the HID lamp needs to have sufficient power supply capacity and withstand voltage to generate a high voltage pulse, and there is a problem that the circuit configuration becomes large and the cost becomes high.

In addition, since it takes time to relight the HID lamp as described above, it is possible to turn on another lamp other than the HID lamp that has been turned off as described in Patent Document 2 described above. Two systems must be prepared, and there is a problem that the cost becomes high and the maintainability deteriorates because of a complicated apparatus configuration.
On the other hand, a light source using temperature radiation, such as an incandescent lamp, has a problem in that it has lower luminous efficiency, energy consumption, and fuel consumption, compared to a light source using luminescence.

  On the other hand, a lamp using discharge between electrodes such as an HID lamp has a characteristic that the discharge voltage takes a certain value. For this reason, the HID lamp has a problem that it is difficult to adjust the light intensity and the power consumption by changing the voltage duty ratio like an incandescent lamp. Of course, it is possible to adjust luminous intensity and power consumption by repeating discharge / extinction instantaneously. However, when a conventional conversion device (for example, an inverter) is used for the power supply section, the power supply section is provided with a surplus power. It is necessary to increase the circuit scale and to reduce the cost.

  The present invention has been made in consideration of such a conventional situation, and an object of the present invention is to adjust the luminous intensity and power consumption of a discharge lamp (HID lamp) and to enable a stable lighting of the discharge lamp. Is to provide.

  In order to achieve the above-described object, a discharge lamp lighting device according to the present invention includes a discharge lamp having a pair of electrodes sealed in a discharge tube together with a predetermined gas, and a predetermined connection connected to the pair of electrodes of the discharge lamp. A power supply unit for supplying power at a level, a lighting capacitor for storing power output from the power supply unit, connected in parallel with the pair of electrodes of the discharge lamp via a lighting step-up transformer, and generating a pulse signal with a predetermined cycle And an oscillator that outputs the pulse signal, and a pulse signal output from the oscillator, and a high voltage pulse is applied to the electrode at a period of the pulse signal to cause a preliminary discharge, and the electric power stored in the lighting capacitor A lamp preliminary lighting circuit for inducing a main discharge between the electrodes to light it is provided.

In the above-described discharge lamp lighting device, the preliminary discharge generated when a high voltage pulse is applied to the electrodes at a predetermined cycle shifts to the main discharge between the pair of electrodes of the discharge lamp and lights up.
Preferably, the oscillator can arbitrarily adjust the period of the pulse signal.
In the above-described discharge lamp lighting device, the period of the preliminary discharge is changed by variably adjusting the period of the pulse signal output from the oscillator, and therefore the lamp lighting period is changed. Therefore, the lighting device for the discharge lamp described above can adjust the lamp luminous intensity and power consumption.

In the lamp preliminary lighting circuit, a preliminary lighting capacitor for storing electric power output from the power supply unit, and a switching element that is turned on / off in response to the pulse signal output from the oscillator and the preliminary lighting capacitor are connected in series. A transformer having a primary winding and a secondary winding that boosts a voltage applied to the primary winding and outputs the boosted voltage to the electrode;
When discharging the power stored in the preliminary lighting capacitor through the switching element turned on by the pulse signal output from the oscillator, the induced voltage generated in the primary winding of the transformer is boosted by the secondary winding. To be provided to the electrode.

  In the above-described discharge lamp lighting device, power (electrostatic energy) stored in the lighting capacitor in a short time is discharged in a very short time through the primary winding of the transformer. At this time, a voltage having a high pulse voltage (about 20000 V to 30000 V) is generated in the secondary winding of the transformer. Since this high voltage is applied to the electrodes, a preliminary discharge is generated in the discharge lamp, and then the main discharge between the electrodes is shifted to turn on the discharge lamp.

Preferably, the power supply unit boosts and outputs a low-voltage direct current to an alternating current having a predetermined voltage value, and a rectifier that rectifies and converts the alternating current output by the conversion circuit (inverter) into direct current A circuit.
The above-described discharge lamp lighting device can light the discharge lamp without requiring a complicated circuit for relighting the lamp.

  According to the discharge lamp lighting device of the present invention, a high voltage is applied to the electrodes according to the pulse signal of the oscillator that is output in a short cycle (generally 15 ms or less), and the preliminary discharge that occurs between the electrodes shifts to the main discharge between the electrodes. The discharge lamp is lit. For this reason, the discharge lamp lighting device of the present invention can change the period of the preliminary discharge by variably adjusting the period of the pulse signal output from the oscillator (oscillator). The period can be adjusted, and the luminous intensity and power consumption of the discharge lamp can be adjusted.

Further, the discharge lamp lighting device of the present invention can variably adjust the period of the pulse signal output from the oscillator, so that the period of preliminary discharge can be changed, and therefore the lamp lighting period can be adjusted. The lamp luminous intensity and power consumption can be adjusted.
On the other hand, the lamp preliminary lighting circuit in the discharge lamp lighting device of the present invention can be configured by a simple circuit having a preliminary lighting capacitor, a switching element, and a transformer. For this reason, a complicated circuit is unnecessary and it is effective also from reduction of a component kind.

  In particular, the discharge lamp lighting device of the present invention temporarily stores the power output from the power supply unit in the lighting capacitor, and uses the power stored in the lighting capacitor to light the discharge lamp. Therefore, it is not necessary to have a continuous load resistance, and there is a great practical effect that it can be realized with a power supply having a simple configuration.

Hereinafter, a discharge lamp lighting device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an example of an embodiment for carrying out the present invention, and the present invention is not limited to this figure.
In this figure, 1 is a discharge lamp provided with a pair of electrodes. The discharge lamp 1 is specifically an HID (high intensity discharge) lamp, such as a high-pressure mercury lamp, a metal halide lamp, or high-pressure sodium. The discharge lamp 1 receives, for example, a direct current (for example, 12V) supplied from an on-board battery (not shown in FIG. 1), converts it into an alternating current of a predetermined voltage (for example, 100V), and outputs the inverter ( It is driven by the power supply unit 2. The output of the inverter 2 is output from a pair of output terminals. One of the output end is grounded and the other, between the diode D ₁ whose anode is grounded anode of the diode diode D ₂ which is connected to the cathode of D ₁ and current limiting capacitor C _{1 (the} details will be described later) Are connected in series. The cathode of the diode D ₂ to the DC output ends of the two diodes D _1, a rectifier circuit composed of D _2, the secondary side of the other end of the lighting step-up transformer T of operating capacitor C _2, one end of which is grounded Is connected to one electrode 1a of the discharge lamp 1. The other electrode 1b of the discharge lamp 1 comprises Incidentally, taken as a pair of electrodes 1a of the grounded discharge lamp 1, the operating capacitor C ₂ in parallel through the secondary side of the 1b and the lighting step-up transformer T is connected Yes.

And from a connection point between the inverter 2 and the current limiting capacitor C _1, between the diode D ₃ whose anode is grounded diode and the anode of the diode D ₄ is connected to the cathode of D _3, another current limiting capacitor C ₃ are connected in series. Diode D ₄ which in this two diodes D _3, D ₄ becomes the DC output ends of another rectifier circuit composed cathode, switching elements (thyristors) whose cathode is grounded Th anode and preliminary operating capacitor C ₄ of the One end is connected. The other end of the preliminary operating capacitor C ₄ is connected to the other end of the transformer, one end of which is grounded (lighting step-up transformer) the primary winding of the T (low pressure side). The secondary winding of the lighting step-up transformer T is connected to the other end of the lighting capacitor C ₂ whose one end is grounded, and the other end is connected to one electrode 1 a of the discharge lamp 1.

  Also, the gate of the thyristor Th receives, for example, a direct current (for example, 12V) supplied from an on-vehicle battery (not shown in FIG. 1) and outputs a pulse signal having a predetermined cycle as a power source. Is connected. The oscillator 11 can change the output cycle of the pulse signal in response to a command from a vehicle-mounted ECU (control device) (not shown).

Now, schematically, the discharge lamp lighting device of the present invention configured as described above is characterized in that a preliminary discharge is generated in one electrode 1a of the discharge lamp 1 at an output period of the oscillator 11, electrode 1a by using the electric power stored the preliminary discharge in advance the operating capacitor C _2, lies in turning on the discharge lamp 1 is shifted to the main discharge between 1b. In other words, the lighting device of discharge lamp of the present invention is directed to on / off the discharge lamp 1 by the discharging / charging operating capacitor C _2.

The operation of the discharge lamp lighting device of the present invention having such characteristics will be described in detail with reference to the flowchart shown in FIG.
For example, when the rated voltage of the discharge lamp 1 is 100V, the power supply unit (inverter) 2 converts the input 12V DC power supplied from, for example, a vehicle-mounted battery into an AC of a predetermined voltage (100V) and outputs the AC. . This AC output is converted to DC again by the two diodes D ₁ and D ₂ via the current limiting capacitor C _1, and then charged by the lighting capacitor C ₂ , and the current is output via the current limiting capacitor C _3. After being converted to direct current by the two diodes D ₃ and D ₄ , the preliminary lighting capacitor C ₄ is charged [step S1].

Charging the operating capacitor C ₂ and the preliminary operating capacitor C ₄ described above is performed for a predetermined time [step S2]. This charging time can be set by a pulse output cycle command given to the oscillator 11 from an ECU (control device) (not shown).
The current limiting capacitor C _1, when the charge of the operating capacitor C ₂ is zero, when charging the operating capacitor C ₂ in step S1, it is provided to prevent overloading the inverter is applied.

Then, the oscillator 11 generates a pulse signal and supplies it to the gate of the thyristor Th when a pulse output cycle (predetermined time elapses) commanded in advance by the ECU is reached [step S3]. Thyristor Th is turned on by a pulse signal outputted from the oscillator 11, the charge stored in the pre-operating capacitor C ₄ is discharged through the primary winding of the lighting step-up transformer T [Step S4]. Current limiting capacitor C ₃ is configured to prevent the step S4 in the thyristor Th is turned on when the excessive load on the inverter 2 is applied, it is provided for the purpose of turning off the pre-operating capacitor C ₄ after discharge thyristor Th.

The charge Q accumulated in the preliminary operating capacitor C ₄ in step S4, a very short time a current change of the primary winding of the lighting step-up transformer T so to be discharged (dQ / dt) becomes steep, lighting A pulsed high voltage of about 20000 V to 30000 V is generated in the secondary winding of the step-up transformer T [Step S5]. Since this high voltage is applied to one electrode 1a of the discharge lamp 1, a preliminary discharge occurs between the electrodes 1a and 1b, and the main discharge between the electrodes 1a and 1b is instantaneously transferred to the discharge lamp 1 ( Lights up for a certain period of time [step S6]. The step S6 of the electrode 1a, the main discharge between 1b, the charge stored in the operating capacitor C ₂ is performed by being released. Then, the process returns to step S1 again turned off once the charge stored in the operating capacitor C ₂ is discharged, and the foregoing processing is repeated. Therefore, the discharge lamp 1 is repeatedly turned on / off in a short cycle.

  That is, when the pulse output cycle of the oscillator 11 is changed during the above-described processing, the lighting / extinguishing ratio (duty) of the discharge lamp 1 changes according to the change. Therefore, the luminous intensity and power consumption of the discharge lamp 1 can be adjusted. Since the lamp flickers or blinks when the pulse output period of the oscillator 11 becomes long, it is desirable that the pulse output period is preferably about several tens Hz to several hundreds Hz (approximately 15 ms or less).

  Thus, in the discharge lamp lighting device of the present invention configured as described above, the preliminary discharge generated between the electrodes 1a and 1b in accordance with the pulse signal of the oscillator 11 output in a short period of about 15 ms or less is instantaneously the main discharge. The discharge lamp 1 is turned on by shifting to. For this reason, the lighting device for the discharge lamp 1 according to the present invention can change the period of the preliminary discharge by variably adjusting the period of the pulse signal output from the oscillator 11. The start cycle can be adjusted, and the luminous intensity and power consumption of the discharge lamp 1 can be adjusted.

Of course, the discharge lamp lighting device according to the present invention repeatedly induces the main discharge in a short cycle as shown in the above-described flowchart even if the discharge arc of the discharge lamp 1 is extinguished for some reason. Can be restarted.
Further, the lamp lighting circuit in the discharge lamp lighting device of the present invention can be constituted by a simple circuit combining a lighting capacitor, a switching element, and a lighting step-up transformer. For this reason, a complicated circuit is unnecessary, and it is effective from the viewpoint of reducing the number of parts.

In the discharge lamp lighting device of the present invention, the DC power output from the power supply unit is temporarily stored in the lighting capacitor, and the discharge lamp is turned on using the DC power stored in the lighting capacitor. Therefore, it is not necessary to have the necessary continuous load resistance, and there is a great practical effect that it can be realized with a power supply having a simple configuration.
The discharge lamp lighting device of the present invention is not limited to the above-described embodiment, and can be implemented with various modifications without departing from the gist of the present invention.

  For example, the present invention is not limited to a vehicle, and can be used for a discharge lamp of a general lighting fixture to adjust luminous intensity and power consumption.

The figure which shows the circuit structure of the lighting device of the discharge lamp which concerns on one Embodiment of this invention. The flowchart which shows the operation | movement process of the lighting device of the discharge lamp shown in FIG.

Explanation of symbols

1 discharge lamps 1a, 1b electrode 2 inverter 11 Oscillator C _{1, C 3} current limiting capacitor C ₂ operating capacitor C ₄ preliminary operating capacitor _{D 1, D 2, D 3} , D 4 diodes T lighting up transformer Th thyristor

Claims (5)

A discharge lamp having a pair of electrodes sealed in a discharge tube together with a predetermined gas;
A power supply connected to a pair of electrodes of the discharge lamp to give a predetermined level of power;
A lighting capacitor connected in parallel with the pair of electrodes of the discharge lamp via a lighting step-up transformer and storing the power output by the power supply unit,
An oscillator that generates and outputs a pulse signal of a predetermined period;
In response to the pulse signal output from the oscillator, a high voltage pulse is applied to the electrodes at the period of the pulse signal to cause a preliminary discharge, and a main discharge is induced between the electrodes by the electric power stored in the lighting capacitor. A discharge lamp lighting device comprising: a lamp preliminary lighting circuit for lighting the lamp.   The discharge lamp lighting device according to claim 1, wherein the oscillator is capable of arbitrarily adjusting a period of the pulse signal. The lamp preliminary lighting circuit, a preliminary lighting capacitor for storing the power output by the power supply unit,
A primary winding in which the preliminary lighting capacitor and a switching element that is turned on / off in response to a pulse signal output from the oscillator are connected in series, and a voltage applied to the primary winding is boosted, and a preliminary winding is provided between the electrodes. A transformer having a secondary winding to cause discharge,
When discharging the power stored in the preliminary lighting capacitor through the switching element turned on by the pulse signal output from the oscillator, the induced voltage generated in the primary winding of the transformer is boosted by the secondary winding. The discharge lamp lighting device according to claim 1, wherein the lighting device is applied to the electrode.   The discharge lamp lighting device according to claim 1, wherein the power supply unit boosts and outputs a low-voltage direct current to a predetermined voltage value. The power supply unit boosts and outputs a low-voltage direct current to an alternating current having a predetermined voltage value; and
The discharge lamp lighting device according to claim 4, further comprising a rectifier circuit that rectifies the alternating current output from the conversion circuit and converts the alternating current into direct current.

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