JP4467941B2 - Discharge lamp lighting device - Google Patents

Description

  The present invention relates to a discharge lamp lighting device for lighting a discharge lamp.

A conventional discharge lamp lighting device (first conventional example) uses a positive potential power source having a different configuration from that of the DC / DC converter as a power source, and a level shift circuit (drive control means) having a constant current circuit configuration causes H Output voltage polarity switching means (hereinafter referred to as H / B) composed of a plurality of switching elements arranged in a letter shape is driven to exchange the negative voltage output from the DC / DC converter with a rectangular AC voltage.
As a power source for the drive control means, two secondary windings are added in addition to the secondary winding for generating a power source for lighting the discharge lamp in the transformer of the DC / DC converter, and independent from the power source for lighting the discharge lamp. Generate power. Therefore, in the discharge lamp lighting device, two power supplies by the secondary winding of the DC / DC converter and a level shift power supply having a constant current circuit configuration are mounted as power supplies for driving the H / B, and a total of three power supplies are mounted. A power supply is required (see, for example, Patent Document 1).

The second conventional example has a DC / DC converter that outputs a positive voltage, and lights the discharge lamp at the positive potential.
The discharge lamp lighting device has drive control means having a bootstrap configuration, but this configuration is difficult to apply to a discharge lamp that is lit with a rectangular wave of DC or extremely low frequency.
Further, since the discharge lamp is lit by a positive potential, a phenomenon that sodium devitrifies occurs inside the discharge lamp.
In addition, the output voltage of the DC / DC converter varies from about 30 V to about 400 V depending on the state of the discharge lamp. From the output voltage, a constant voltage required by the drive control means is secured, and the required current flows. For this purpose, the ratings of circuit components such as series resistors and Zener diodes are increased so that they can withstand a large current supplied from a power supply at 400 V with a low resistance value that allows a predetermined current to flow from the power supply at 30 V. There is a need (see, for example, Patent Document 2).

JP-A-10-41083 (pages 5 to 8, FIG. 1) JP-A-10-321393 (pages 4 to 12, FIG. 1)

Since the conventional discharge lamp lighting device is configured as described above, in the case of the first conventional example, it is necessary to mount a plurality of power supplies, and there is a problem that the circuit configuration is complicated and causes an increase in size.
In the case of the second conventional example, it is difficult to apply to a discharge lamp that is lit with DC or a very low frequency rectangular wave, and there is a problem in that sodium is devitrified inside the discharge lamp. In addition, there is a problem that may increase the rating of the component parts.

  The present invention has been made to solve the above-described problems, and it is possible to obtain a DC power source by simply mounting a single power source without causing a phenomenon of sodium devitrification and an increase in the rating of component parts. It is an object of the present invention to provide a discharge lamp lighting device that can be easily applied to a discharge lamp that is lit with a very low frequency rectangular wave.

The discharge lamp lighting device according to the present invention comprises a converting means for converting a DC / DC converter for generating a negative voltage by boosting a DC power supply voltage, a plurality of DC voltage that will be a switching element in a rectangular AC voltage, the By using a direct current power source as the high voltage side power source supplied to the conversion means, using a negative voltage power source composed of the DC / DC converter as the low voltage side power source, and connecting the direct current power source and the negative voltage power source in series. In a discharge lamp lighting device that supplies an added voltage of both voltages to a discharge lamp , the negative voltage output of the DC / DC converter is generated by a negative voltage output generated in a secondary winding of a transformer constituting the DC / DC converter. generated, high control power supply voltage from the DC power supply voltage for driving control means for opening and closing the switching elements constituting the converter means, the DC / DC converter Constituting a is obtained so as to generate the positive voltage output generated in the secondary winding of the transformer.

According to the invention, comprising converting means for converting a DC / DC converter for generating a negative voltage by boosting a DC power supply voltage, a plurality of DC voltage that will be a switching element in a rectangular AC voltage, supplied to the conversion means Using a DC power source as the high voltage side power source and a negative voltage power source composed of the DC / DC converter as the low voltage side power source , adding both voltages by connecting the DC power source and the negative voltage power source in series In the discharge lamp lighting device for supplying voltage to the discharge lamp and lighting it, the negative voltage output of the DC / DC converter is generated by the negative voltage output generated in the secondary winding of the transformer constituting the DC / DC converter, high control power supply voltage from the DC power supply voltage for driving control means for opening and closing the switching elements constituting the converter constitute the DC / DC converter DOO Since it is configured to generate the positive voltage output generated in the secondary winding of Nsu, without increasing the size of the rating of the phenomenon and components sodium devitrified, simply mounting the single power source, There is an effect that can also be applied to a discharge lamp that is lit by DC or a very low frequency rectangular wave.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a discharge lamp lighting device according to Embodiment 1 of the present invention. In the figure, a DC power source 1 supplies a DC voltage, and a DC / DC converter 2 boosts the DC voltage supplied from the DC power source 1 and outputs a negative voltage. The DC / DC converter 2 includes a switching element 3, a transformer (primary winding 4, secondary winding 5), a capacitor 6, and a diode 7.
The rectifier circuit 11 rectifies the forward voltage generated in the secondary winding 5 of the DC / DC converter 2, and supplies power to level shift circuits 12a, 12b, 13a, 13b, 14a, 14b, 15a, 15b having a constant current circuit configuration. To generate a voltage. The level shift circuits 12a, 12b, 13a, 13b, 14a, 14b, 15a, and 15b having a constant current circuit configuration transmit intermittent control by the microcomputer 16 by a constant current, and drive the switching elements 21 to 24 by FETs.

H / B is constituted by the switching elements 21 to 24, and the negative voltage output from the DC / DC converter 2 is converted into a rectangular wave voltage by being opened and closed by the drive control means.
An IGN (igniter) 25 superimposes a high voltage that causes breakdown of the discharge lamp 26 on the rectangular AC voltage generated by the H / B, and causes the discharge lamp 26 to break down.

Next, the operation will be described.
First, in the DC / DC converter 2, the switching element 3 is driven by a drive circuit (not shown) to boost the DC voltage V _BAT generated from the DC power supply 1.
As shown in FIG. 2A, the switching element 3 of the DC / DC converter 2 is driven at a timing at which the ON period and the OFF period are alternately repeated.
As a result, the potential V _{0 of the} secondary winding 5 of the DC / DC converter 2 (the potential at the end of the secondary winding 5) is equal to the forward voltage N × V _BAT and the fly voltage as shown in FIG. back voltage V _- are alternately repeated. When the discharge lamp 26 is a mercury-free discharge lamp, the winding ratio is, for example, 1: 2.5. If V _BAT = 10V to 20V, the forward voltage (N × V _BAT ) is + 25V to + 50V.

The rectifier circuit 11 extracts the forward voltage N × V _BAT from the potential V _{0 of the} secondary winding 5 of the DC / DC converter 2 and smoothes it in order to generate the power source of the drive control means for driving the H / B. The power sources of the constant current circuits 12a, 12b to 15a, 15b are used.
Here, the rectifier circuit 11 is the flyback voltage V _- rather, the reason for outputting removed forward voltage N × _{V BAT} is the flyback voltage V _-, the change to approximately 30V~400V in accordance with the state of the discharge lamp 26 to so, the flyback voltage V _- to use as a power source of the drive control means, once, or step-down control to an arbitrary constant voltage is undesirable since it is necessary to increase the element withstand voltage of the drive control means.
On the other hand, if the forward voltage is N × V _BAT , it becomes a voltage having a winding ratio N with respect to the DC voltage V _BAT regardless of the state of the discharge lamp 26. For example, N = 2.5 and V _BAT = 9 to 16 Then, N × V _BAT is 22.5 to 40 V, which is a good voltage power source.

The level shift circuits 12a and 12b having a constant current circuit configuration rectify the forward voltage of N × V _BAT generated in the secondary winding of the transformer by the rectifier circuit 11 to generate a constant current for driving H / B. To do.
As shown in FIG. 3, the current _{I 1} flowing through the constant current circuit 12b voltage _{(R 2} × _{I 1)} is generated in the resistor _{R 2,} the resistance of the voltage _{(R 2} × _{I 1)} is a constant current circuit 12b Applied between the base and emitter of _Tr from R ₂ , current I ₂ flows, a voltage (R ₄ × I ₂ ) is generated in the resistor R ₄ and becomes a drive signal for the switching element 21.
Similarly, the constant current circuits 13a, 13b to 15a and 15b also generate constant currents and generate drive signals for the switching elements 22 to 24.

The microcomputer 16 controls the level shift circuits 12a, 12b to 15a, 15b having a constant current circuit configuration, and drives H / B.
That is, the switching of the switching elements 21 to 24 of H / B is controlled so that the voltage output from H / B becomes a rectangular AC voltage.

The switching elements 21 to 24 are opened and closed by a drive control signal generated by the microcomputer 16 and convert the negative voltage output from the DC / DC converter 2 into a rectangular wave AC voltage.
The IGN 25 applies a rectangular wave voltage (high potential side potential: 10 to 20 V, low potential side potential: −10 to −190 V) converted by the switching elements 21 to 24 to the discharge lamp, and then applies a high voltage pulse. By superimposing, the electrodes of the discharge lamp are insulated and destroyed, and the discharge lamp 26 is turned on.
Further, since a negative potential is applied to the discharge lamp 26, the phenomenon of sodium devitrification does not occur.

  As is apparent from the above, according to the first embodiment, the drive control of the switching element using the forward side voltage generated in the secondary winding 5 of the transformer of the DC / DC converter 2 that outputs a negative voltage as a power source. Since the switching elements 21 to 24 are configured to open and close by means, the DC or the like can be obtained by simply mounting a single power source without causing the phenomenon of sodium devitrification and the increase in the rating of the component parts. There is an effect that can also be applied to the discharge lamp 26 that is lit with a very low frequency rectangular wave.

Further, according to the first embodiment, the power source for driving control of the switching elements 21 to 24 is generated from the forward voltage generated in the secondary winding 5 of the transformer of the DC / DC converter 2, and the driving control power source is generated. Using the power supply, drive control is performed by a level shift circuit having a constant current circuit configuration, and the switching elements 21 to 24 can be driven.
Further, according to the first embodiment, when the discharge lamp 26 is a mercury-free discharge lamp, the forward voltage is extracted from the end of the secondary winding 5 of the DC / DC converter 2. There is an effect that a power source for driving control of the switching elements 21 to 24 can be generated without attaching an intermediate tap or the like to the secondary winding 5 of the transformer of the DC / DC converter 2. That is, when the discharge lamp 26 is a mercury-free discharge lamp, the winding ratio N of the primary winding 4 and the secondary winding 5 is set to about 1: 2.5, so that the secondary winding 5 A forward voltage having an appropriate potential can be taken out without attaching an intermediate tap to the base plate.

  Furthermore, according to the first embodiment, since the level shift circuits 12a, 12b to 15a, 15b have a constant current circuit configuration, even if the power source of the drive control means is not an arbitrary constant voltage, the H / B switching element 21 is used. Since the drive voltage of ˜24 can be determined to an arbitrary constant voltage, it is not necessary to control the power source and voltage of the drive control means to be arbitrary constant, and the circuit configuration can be simplified.

Embodiment 2. FIG.
In the first embodiment described above, the forward voltage is extracted from the end of the secondary winding 5 of the transformer of the DC / DC converter 2, but an intermediate tap is provided in the secondary winding 5 of the transformer of the DC / DC converter 2. And a forward voltage may be taken out from the intermediate tap. Thereby, the same effects as those of the first embodiment can be obtained.
Specifically, when the discharge lamp 26 not using mercury is lit using the DC / DC converter 2 for the discharge lamp using mercury, the primary winding 4 of the transformer of the DC / DC converter 2 Since the winding ratio N of the secondary winding 5 is set to about 1: 6, when the forward voltage is taken out from the end of the secondary winding 5, if V _BAT = 10V to 20V, the forward voltage is + 60V. As a result, the control voltage becomes too large.
Therefore, in the second embodiment, an intermediate tap is provided in the secondary winding 5 so that the winding ratio is 1: 2.5 + 3.5 and the forward voltage is extracted from the intermediate tap. Thus, if V _BAT = 10V to 20V, the forward voltage becomes + 25V to + 50V.

It is a block diagram which shows the discharge lamp lighting device by Embodiment 1 of this invention. It is explanatory drawing which shows the drive timing etc. of a DC / DC converter. It is explanatory drawing which shows the production | generation of the power supply for drive control for switching.

Explanation of symbols

  1 DC power supply, 2 DC / DC converter, 3 FET, 4 primary winding (transformer), 5 secondary winding (transformer), 6 capacitor, 7 diode, 11 rectifier circuit (drive control means), 12a, 12b constant Current circuit (drive control means), 13a, 13b Constant current circuit (drive control means), 14a, 14b Constant current circuit (drive control means), 15a, 15b Constant current circuit (drive control means), 16 Microcomputer (drive control means) ) 21-24 FET (switching element, applied voltage generating means), 25 IGN (applied voltage generating means).

Claims (5)

A DC / DC converter for generating a negative voltage by boosting a DC power supply voltage, comprising a conversion means for converting a DC voltage that consists of a plurality of switching elements in a rectangular AC voltage, power supply and high-voltage side to the conversion means As a power source on the low voltage side, a negative voltage power source composed of the above-mentioned DC / DC converter is used as a power source on the low voltage side, and the sum of both DC power source and negative voltage power source is connected to the discharge lamp . In the discharge lamp lighting device that is lit, the negative voltage output of the DC / DC converter is generated by the negative voltage output generated in the secondary winding of the transformer that constitutes the DC / DC converter, and switching that constitutes the conversion means. high control power supply voltage from the DC power supply voltage for driving control means for opening and closing of the device, the secondary winding of the transformer constituting the DC / DC converter The discharge lamp lighting device and generating the positive voltage output to raw.   2. The discharge lamp lighting device according to claim 1, wherein the drive control means drives the switching element by a power source generated by a forward-side voltage generated in the secondary winding of the transformer of the DC / DC converter. .   The drive control means converts the ratio of the turns of the primary winding and secondary winding of the transformer of the DC / DC converter into a rectangular AC voltage so that the voltage necessary for drive control is generated, A power source that uses a forward voltage generated at the end of the winding is used, and a flyback voltage generated at the end of the secondary winding is used as a power source for lighting a discharge lamp. Item 3. A discharge lamp lighting device according to Item 2.   The drive control means is provided with an intermediate tap in the secondary winding of the transformer of the DC / DC converter, extracts a forward voltage generated in the intermediate tap, serves as a power source, and a fly generated at the end of the secondary winding. 3. The discharge lamp lighting device according to claim 2, wherein a back voltage is taken out and used as a power source for lighting the discharge lamp.   The drive control means uses a level shift circuit having a constant current circuit configuration to transmit a signal for driving the switching element, thereby generating a power source for the drive control means generated from the forward voltage of the secondary winding of the transformer of the DC / DC converter. The discharge lamp lighting device according to claim 1, wherein the voltage is not constant.

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