JP3180353B2 - Discharge lamp lighting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for lighting a high-pressure discharge lamp such as a metal halide lamp, and more particularly to control of the light output of the discharge lamp.

[0002]

2. Description of the Related Art FIG. 6 shows a configuration diagram of a conventional apparatus disclosed in, for example, JP-A-2-136343. In the figure, 1 is a lighting circuit of a metal halide lamp for an automobile,
Reference numeral 2 denotes a battery as a DC power supply, 3 denotes a DC (direct current) booster circuit, 4 denotes an inverter circuit, 5 denotes an LC load and an igniter circuit, 6 denotes a metal halide lamp, and 7 denotes an igniter starting circuit. Reference numeral 8 denotes a control circuit which detects a turning-off time of the lamp 6 and adjusts the boosting amount of the DC boosting circuit 3 in accordance with the detected time so that a current (overcurrent) equal to or more than the rated current flows through the lamp 6 for a predetermined time. To control.

Next, the operation will be described. This lamp 6
The control circuit 8 includes an extinguishing time detecting circuit for detecting the extinguishing time of the lamp 6 in accordance with an output signal of the control circuit 8 in order to speed up the rise of the luminous flux at the time of starting. , A control pulse having a required duty cycle is generated, and the output voltage of the DC boosting circuit 4 is controlled. The time during which the overcurrent flows is controlled in accordance with the signal from the light-off time detection circuit provided in the control circuit 8 so that the luminous flux reaches the rated value quickly when the lamp 6 is turned on and turned on again. As described above, in the conventional example, the overcurrent time is varied according to the elapsed time from the turning off of the lamp to the next lighting, that is, the turning off time.

[0004]

In the conventional example, the overcurrent flowing time is controlled by the light-off time.
The power supplied to the lamp changes due to variations and fluctuations in the lamp voltage, the ambient temperature of the lamp, and the like, which may cause inconvenience such as an excessive peak in the light output (luminous flux) at the time of starting.

The present invention has been made to solve such a problem, and an excessive peak does not appear in the light output at the time of starting, and a constant light output can be obtained immediately after the start of lighting. It is an object to provide a discharge lamp lighting device.

[0006]

In order to achieve the above object, according to the present invention, a discharge lamp lighting device is configured as in the following (1 ) . (1) Power supply unit that supplies starting voltage and power to discharge lamp
Lamp voltage detection for detecting a lamp voltage of the discharge lamp
And a power supply according to an output of the lamp voltage detection unit.
Discharge lamp lighting device comprising a control unit for controlling the power supplied to the discharge unit.
Wherein the control unit is configured to set the discharge lamp in advance.
Lamp power and lamp voltage required to maintain a constant light output
The output of the lamp voltage detector based on the corresponding characteristics of
The power supply of the voltage supply unit is controlled in accordance with
A discharge lamp lighting device for controlling supply power by giving priority to not exceeding predetermined maximum allowable lamp current and maximum allowable lamp power.

[0007]

[0008] According to the configuration (1 ) , the control unit controls the power supply unit in accordance with the lamp voltage based on a predetermined characteristic corresponding to the lamp power and the lamp voltage required for keeping the light output of the discharge lamp constant. To control the power supply . Further, the control unit controls the electric power supplied by preference that does not exceed the maximum allowable lamp current and the maximum allowable lamp power set in advance.

[0009]

The present invention will be described below in detail with reference to examples. FIG. 1 shows a "discharge lamp lighting device" according to an embodiment of the present invention.
2, FIG. 3, FIG. 4, and FIG. 5 are operation explanatory diagrams of the present embodiment. First, the present embodiment will be schematically described with reference to FIGS.

In a high-pressure discharge lamp such as a metal halide lamp used in this embodiment, when the lamp is turned on, the lamp voltage is initially low (the vapor pressure inside the arc tube is low) and gradually rises to the final value ( Rated value).

[0011] Such a change in the lamp voltage is caused by a change in the vapor pressure inside the arc tube. The vapor pressure changes the efficiency of the lamp. FIG. 2 shows an example showing this state. FIG. 2 shows the relationship between lamp voltage and lamp efficiency. As described above, when the efficiency at the lamp voltage (approximately 85 V in the figure) at the rated power of the lamp is 100%, the efficiency is considerably reduced when the voltage is low.

Therefore, when such a high-pressure discharge lamp is used to control the light output to be substantially constant before the lamp voltage reaches the rated value as shown in FIG. 5, for example, at time t _{1 in} FIG. since the lamp voltage is low and V _L1, it must be greater than the rated value of this time the lamp power.

FIG. 3 shows the required lamp power for controlling the light output constant with respect to the lamp voltage. This graph shows the characteristics when the lamp power at the rated lamp voltage is 100%. Thus, by controlling the power supplied to the lamp, the light output of the lamp can be made quick and flat. However, in order to obtain the same light output as in the rated state immediately after the start of lighting with a very low lamp voltage, the power supplied to the lamp must be rapidly increased as indicated by the broken line in FIG.

[0014] Such excessive power supply may damage the lamp, and usually exceeds the rated power (current).
Has a limit value (allowable overpower value). Therefore, in the present embodiment, control is performed so that the rise of the optical output is accelerated and the overpower for obtaining a flat optical output is provided within a predetermined range as shown in FIG.

Next, this embodiment will be described with reference to FIG.
In the figure, reference numeral 2 denotes a DC power supply, 4 denotes a high-frequency generating means which is constituted by an inverter, 6 denotes a discharge lamp composed of a metal halide lamp, 7 denotes a starting circuit for generating a high voltage for starting discharge of the discharge lamp 6, Reference numeral 9 denotes a control unit for controlling the output frequency of the inverter 4, and reference numeral 10 denotes an impedance for limiting the lamp current of the discharge lamp 6, which is constituted by a choke coil which is an inductive reactance. Here, 4, 7, and 10 constitute the power supply unit 12. 11
Is a lamp voltage detecting unit for detecting a lamp voltage, generates a signal corresponding to the lamp voltage during lighting, and the control unit 9 generates a predetermined frequency signal in response to the signal. The control unit 9 sets a limit by the maximum allowable lamp current of the discharge lamp 6 and the maximum allowable lamp power in advance, and applies a limiter (does not increase the output by a predetermined value or more) to the command frequency by the lamp voltage detection. Operation.

That is, the control unit 9 controls the electric power in accordance with the output of the lamp voltage detecting unit 11 based on the preset characteristics of the lamp power and the lamp voltage required for keeping the light output of the discharge lamp 6 constant. The power supply is controlled by controlling the output frequency of the supply unit 12.

FIG. 4 is a diagram showing operating characteristics of the present embodiment. In the figure, the discharge lamp 6 at time t ₀ is assumed to begin discharge. Then, the lamp voltage gradually rises as indicated by a dashed line. Thus, while the lamp current do increase operating an optical output of the discharge lamp 6 in an attempt rise to flat as in FIG. 5, the maximum allowable lamp current until time t ₁ (in an A
Maintaining the A ₁ so as not to exceed to) and is set to _1. Next, when the lamp voltage rises gradually lamp power is increased, again maintaining the W ₁ so as not to exceed the maximum allowable power (and is set to W ₁ shown).
Next Beyond time t _2, the so required lamp power is W ₁ or less, the discharge lamp 6 is required lamp power in accordance with each of the lamp voltage value flowing lamp current to be supplied. For controlling the lamp current (power), the output frequency of the inverter 4 may be controlled, for example, as shown by a broken line in FIG. Specifically, it can be realized by the control unit 9 switching the switching device of the inverter 4 at a desired frequency. The conversion from the ramp voltage signal to the frequency signal may be configured using a voltage controlled oscillator (VCO) or the like.

In the embodiment, the output frequency of the inverter 4 is controlled in order to control the supply power. However, the present invention is not limited to this, and other means such as the input DC voltage value of the inverter may be used. It may be controlled. In this case, instead of controlling the output frequency of the inverter according to the lamp voltage described above, the power supply unit 12 includes a DC voltage converter such as a DC-DC converter on the input side of the inverter and a lamp. The control unit may control the output voltage of the DC voltage converter using the output signal of the voltage detection unit.

According to the present invention, not only when the lamp is turned on (cold start) from a cold state, but also when the lamp is turned on from a still warm state immediately after the lamp is turned off, the lamp current (power ) Can also reduce the change in the light output of the discharge lamp up to the steady state.

In addition, the relationship between the lamp current and the power is that lamp power is proportional to lamp voltage × lamp current. Therefore, in the above description, even if the lamp current is controlled, the lamp power is indirectly controlled. However, it goes without saying that the lamp power and the lamp current component may be actually detected and calculated to detect and control the lamp power.

Further, it is also possible to control the power supply to the discharge lamp without delaying the rise of the light output at the time of starting and setting the maximum allowable lamp current and the maximum allowable lamp power. .

[0022]

As described above, according to the present invention,
At the time of starting, it is possible to prevent an excessive peak from occurring in the light output of the discharge lamp, and to obtain a constant light output immediately after the start of lighting.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment.

FIG. 2 is a diagram illustrating the operation of the embodiment.

FIG. 3 is an explanatory diagram of the operation of the embodiment.

FIG. 4 is a diagram illustrating an operation of the embodiment.

FIG. 5 is a diagram illustrating the operation of the embodiment.

FIG. 6 is a block diagram of a conventional example.

[Explanation of symbols]

 6 Discharge lamp 9 Control unit 11 Lamp voltage detection unit 12 Power supply unit In the drawings, the same reference numerals indicate the same or corresponding parts.

Continued on the front page (72) Inventor Yoyo Otsuka 2--14-40 Ofuna, Kamakura City, Kanagawa Prefecture Inside of Living System Research Laboratory, Mitsubishi Electric Corporation (72) Inventor Kazushi Tanegashima 2-33 Miwa, Mita City, Hyogo Prefecture No. Mitsubishi Electric Corporation Mita Works (72) Inventor Kenji Nakamura 2-33 Miwa, Mita City, Hyogo Prefecture Inside Mitsubishi Electric Co., Mita Works (72) Inventor Takashi Osawa 2-33 Miwa, Mita City, Hyogo Prefecture No. Mitsubishi Electric Corporation Mita Works (56) References JP-A-4-141988 (JP, A) JP-A-2-27895 (JP, A) JP-A-56-7392 (JP, A) JP-A-2 JP-A-215090 (JP, A) JP-A-2-177298 (JP, A) JP-A-62-259391 (JP, A) JP-A-4-118889 (JP, A) JP-A-3-283389 (JP, A) JP-A-3-138894 (JP, A) JP-A-3-54040 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05B 41/14-41/298

Claims (1)

(57) [Claims] 1. An electric power for supplying a starting voltage and electric power to a discharge lamp.
A supply unit for detecting a lamp voltage of the discharge lamp;
A pressure detector and the lamp according to the output of the lamp voltage detector.
Discharge lamp comprising a control unit for controlling the power supply of the power supply unit
The lighting device, wherein the control unit is set in advance,
Lamp power and run required to keep the light output of the discharge lamp constant
The lamp voltage detection unit based on the corresponding characteristic of the lamp voltage.
Controlling the supply power of the voltage supply unit according to the output of
The, and the and the maximum allowable lamp current and the maximum allowable lamp lamp lighting device release you, wherein the power and controls the power supplied by the priority that it does not exceed a previously set.