JPH04342993A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To stabilize the output light in a short period of time by supplying the power at the time of starting, first in an amount several time as large as the rating until the lamp voltage attains the No.1 specified value, and then according to a specific formula until the lamp voltage attains the No.2 specified value, and thereafter decreasing the power by a certain amount at each unitary interval time until the converter output power becomes a specified value. CONSTITUTION:At starting, a high voltage generator circuit 10 generates a high voltage to light up a discharge lamp 8, and a lap state sensing circuit 7 senses the lamp current while a power sensing circuit 4 senses power information. A control circuit 3 controls a DC-DC converter 2 in conformity to information of circuits 4, 7 to supply the lamp 8 with a power several times as large as the rating until the lamp voltage attains the specified value. The control circuit 3 also controls so that the converter 2 power becomes the starting power subtracted by the lamp voltage which is multiplied with specified current until the lamp voltage becomes the No.2 specified value. Thereafter the control circuit 3 decreases the output power of the converter 2 by a certain amount at each until interval time so as to maintain the rated power finally. Thereby the output light is stabilized in a short period of time.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] This invention relates to a lighting device for discharge lamps such as high-pressure mercury lamps and metal halide lamps.
In particular, it relates to control at the time of starting.

0002

2. Description of the Related Art FIG. 6 is a block diagram of a lighting device for a discharge lamp of this type. In the figure, 1 is a DC power supply, 2 is a DC-DC converter that boosts the voltage of the DC power supply 1 to a required value, 8 is a discharge lamp that is the load of the device, and 6 is a choke coil that controls the current of the discharge lamp 8. , 9 is an igniter circuit that applies a high voltage to the discharge lamp 8 during startup to cause dielectric breakdown of the sealed gas.

[0003] This discharge lamp lighting device does not perform control at the time of starting.

0004

In a discharge lamp lighting device that does not perform the above-mentioned startup control, the relationship between the elapsed time after lighting and the light output (luminous flux) is as shown in FIG.

As is clear from the figure, it takes a considerable amount of time for the light output to stabilize after the light is turned on, and the light output changes significantly from the time the light is turned on until the light output stabilizes.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a discharge lamp lighting device in which the light output is stabilized in a short period of time upon startup.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a discharge lamp lighting device with the following features (1) and (2).
).

(1) DC-DC converter and the DC-DC converter
An inverter connected to the output side of the DC converter, an inductor connected in series to the output side of the inverter, and an output end connected to the load discharge lamp, and an output power detection means for detecting the output power of the DC-DC converter. and a lamp state detecting means for detecting the lamp voltage and lamp current of the load discharge lamp; the output of the output power detecting means and the output of the lamp state detecting means are input;
- A discharge lamp lighting device comprising: a control means for controlling the output power of the DC converter, wherein the control means detects lighting based on the lamp voltage or lamp current, and then the lamp voltage becomes a first predetermined value. until the output power of the DC-DC converter becomes a starting power several times the rated power, and then until the lamp voltage reaches a second predetermined value,
The output power of the DC-DC converter is controlled to be the value obtained by subtracting the power equal to the lamp voltage multiplied by a predetermined current value from the starting power, and then until the output power of the DC-DC converter reaches the predetermined value. , a discharge lamp lighting device that controls the output power of a DC-DC converter to decrease by a constant amount of power every unit time.

(2) It has an output voltage detection means for detecting the output voltage of the DC-DC converter, and the control means controls the DC-DC voltage according to the output of the voltage detection means until lighting is detected at the time of starting. The discharge lamp lighting device according to (1) above, which controls the output voltage of the DC converter to be constant.

0010

[Operation] According to the configurations (1) and (2) above, upon starting, starting power several times the rated power is supplied to the discharge lamp from lighting until the lamp voltage reaches the first predetermined value. After that, while the lamp voltage reaches the second predetermined value, the power equal to "starting power - K (predetermined current)/lamp voltage" is supplied, and thereafter until the output power of the DC-DC converter reaches the predetermined value. , power is supplied that decreases by a constant amount per unit time.

[0011] In the configuration (2), the output voltage of the DC-DC converter is maintained constant until the light is turned on at the time of starting.

0012

[Examples] The present invention will be explained in detail with reference to Examples below. FIG. 1 is a block diagram of a "discharge lamp lighting device" which is an embodiment, FIGS. 2 and 3 are diagrams explaining the operation of this embodiment, FIG. 4 is a flowchart showing the operation of this embodiment, and FIG. 5 is a flowchart showing the operation of this embodiment. It is a figure showing the relationship between elapsed time and light output in .

In FIG. 1, 1 is a DC power supply, 2 is a DC-DC converter with variable output voltage and output power, and 4 is a DC-DC converter.
a power detection circuit that detects the output power of the DC converter 2;
5 is an inverter that converts the output of the DC-DC converter 4 into alternating current; 6 is a choke coil that limits the lamp current (
7 is a lamp state detection circuit for detecting lamp voltage and lamp current, and 8 is a discharge lamp. Reference numeral 10 denotes a high voltage generating circuit that applies a high voltage generated in a resonant circuit to the discharge lamp 8 at the time of starting, thereby causing dielectric breakdown of the filled gas.

3 inputs information on the output power and output voltage of the DC-DC converter 2 from the power detection circuit 4 and information on the lamp voltage and lamp current from the lamp state detection circuit 7, and This is a control circuit that controls output power or output voltage.

The operation will be explained below with reference to FIGS. 2 to 4. When a light switch (not shown) is turned on, the control circuit 3 controls the output voltage of the DC-DC converter 2 to be constant as shown in FIG. 2 based on voltage information from the power detection circuit 4 (see FIG. 4). (See S1). At this time, the high voltage generating circuit 10 supplies a high voltage to the discharge lamp 8, so that the gas filled in the discharge lamp 8 causes dielectric breakdown and is turned on. When the lamp state detection circuit 7 detects the lamp current caused by this lighting (S2, NO), the control circuit 3 determines that the output power of the DC-DC converter 2 is equal to the rated power of the discharge lamp 8 based on the power information of the power detection circuit 4. The starting power, which is several times the electric power (
(Figure 3A)
See period, S3). When the lamp state detection circuit 8 detects that the lamp voltage exceeds the first predetermined value VL1 (S4, YES), the control circuit 3 then uses the power information of the power detection circuit 4 and the voltage information of the lamp state detection circuit 7. Based on this, the output power of the DC-DC converter 2 is controlled to the value of (the starting power - K·lamp voltage) (see period B in FIG. 3, S5), and the lamp voltage further increases to a second predetermined value V.
When the lamp state detection circuit 8 detects that L2 is exceeded (
After that, the output voltage of the DC-DC converter 2 is controlled to decrease by a fixed value every unit time (see period C in FIG. 3, S7, S8), and the power detection circuit 4 detects that the rated power has been reached. When detected (S9, YES), control is performed to maintain the rated power (see period in Figure 3D, S
10).

The reason why the output power of the DC-DC converter 2, that is, the power supplied to the discharge lamp 8 is controlled as shown in FIG. 3 is as follows. The lamp voltage is the first predetermined value V
At L1, the optical output rises, and thereafter the optical output becomes a function of the lamp voltage, so the output power is controlled according to the lamp voltage. When the lamp voltage reaches the second predetermined value VL2,
Since the light output approaches the rated value and the lamp voltage changes slowly, the output voltage is controlled over time instead of the lamp voltage.

In this embodiment, since the output power of the DC-DC converter 2 is controlled as described above, the optical output stabilizes at a substantially constant value immediately after lighting, as shown in FIG. In addition, since the output voltage of the DC-DC converter 2 is controlled to be constant until the light turns on at startup, a stable high voltage can be obtained in the high voltage generation circuit 10 regardless of voltage fluctuations in the DC power supply 1, and the light turns on. becomes certain.

In the embodiment, lighting is detected using the lamp current, but it may also be detected using the lamp voltage.

[0019]

As described above, according to the present invention, the optical output is stabilized in a short time at the time of starting. Furthermore, in the invention of claim 2, the light is reliably lit regardless of voltage fluctuations of the DC power supply.

[Brief explanation of drawings]

[Figure 1] Block diagram of the embodiment

[Fig. 2] A diagram showing the relationship between the elapsed time before and after lighting of the DC-DC converter and the output voltage in the example

[Fig. 3] A diagram showing the relationship between elapsed time and output power of the DC-DC converter in the example.

[Figure 4] Flowchart showing the operation of the embodiment

[Figure 5] Diagram showing the relationship between elapsed time and light output in the example

[Figure 6] Block diagram of conventional example

[Figure 7] Diagram showing the relationship between elapsed time and light output in the conventional example

[Explanation of symbols]

2 DC-DC converter 3 Control circuit 4 Power detection circuit 5 Inverter 6 Choke coil 7 Lamp status detection circuit 8 Discharge lamp

Claims (2)

[Claims] [Claim 1] A DC-DC converter and the DC-D
an inverter connected to the output side of the C converter; an inductor connected in series to the output side of the inverter; and an output end to which the load discharge lamp is connected; and output power detection means for detecting the output power of the DC-DC converter. and a lamp state detecting means for detecting the lamp voltage and lamp current of the load discharge lamp; the output of the output power detecting means and the output of the lamp state detecting means are input;
A discharge lamp lighting device comprising a control means for controlling output power of a DC converter, wherein the control means detects lighting based on lamp voltage or lamp current, and then controls the lamp voltage until the lamp voltage reaches a first predetermined value. , the output power of the DC-DC converter is controlled to be a starting power several times the rated power, and then D is controlled until the lamp voltage reaches a second predetermined value.
The output power of the C-DC converter is controlled to be the value obtained by subtracting the power equal to the lamp voltage multiplied by a predetermined current value from the starting power, and then the output power of the DC-DC converter is controlled until the output power of the DC-DC converter reaches the predetermined value. A discharge lamp lighting device, characterized in that the output power of the DC-DC converter is controlled to decrease by a constant amount of power every unit time. 2. An output voltage detection means for detecting the output voltage of the DC-DC converter, and the control means controls the DC-DC voltage according to the output of the voltage detection means until lighting is detected at the time of starting. 2. The discharge lamp lighting device according to claim 1, wherein the discharge lamp lighting device controls the output voltage of the converter to be constant.