JP2000133489A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device capable of rapidly lighting a discharge lamp and quickly performing light modulation after lighting. SOLUTION: This discharge lamp lighting device is provided with switching elements 10a, 10b connected between a D.C. power source 3 and a discharge lamp 2, a controlling-driving circuit 11 that turns on and off the switching elements 10a, 10b for preheating and lighting the discharge lamp 2, a light modulation circuit 14 that feeds a light modulation signal to the controlling- driving circuit 11 for performing the light modulation of the discharge lamp 2, a timer circuit 15 for outputting an on-signal for starting the discharge lamp 2 to the controlling-driving circuit 11 after a predetermined time elapses after the D.C. power source 3 turned on, and a reset circuit 18 that detects that a current more than a certain value is flowing through the discharge lamp 2 and then, electrically connects the light modulation circuit 14 to the controlling-driving circuit 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device for preheating and lighting a discharge lamp with a high-frequency electric signal.

[0002]

2. Description of the Related Art Conventionally, in order to increase the efficiency of a discharge lamp, a high-frequency lighting method using a transistor inverter has been used. As an example of a discharge lamp lighting device of a high frequency lighting system, there is a discharge lamp lighting device disclosed in Japanese Patent Application Laid-Open No. 1-309297. This discharge lamp lighting device includes a switching circuit for turning on / off a switching element of an inverter circuit for preheating and lighting a discharge lamp connected to an output terminal, and a drive connected to the switching circuit. A light control circuit connected to the drive circuit and controlling the operation of the drive circuit to perform light control on the discharge lamp; and a light control circuit for outputting an ON signal only for a predetermined time from when the power supply is turned on. A first timer circuit, and a second timer circuit that outputs a signal for starting the operation of the dimming circuit after a predetermined time has elapsed from when the power supply is turned on.

The length of time from when the power supply is turned on to when the second timer circuit outputs a signal for starting the operation of the dimming circuit is set in advance.

[0004]

In the above-described discharge lamp lighting device, the time required from when the power is turned on to when the operation of the dimming circuit is started is set in advance. Generally, the preheating time of the filament varies depending on the environment around the discharge lamp. For example, in winter when the ambient temperature is low, the filament preheating time is longer than in summer when the ambient temperature is high. Therefore, the second timer circuit operates between the time when the power is turned on and the time when the second timer circuit outputs a signal to start the operation of the dimming circuit even under a bad condition such that the preheating time of the filament is long. It is necessary to set a longer time so that the preheating of the filament is completed and a current flows through the discharge lamp, and the discharge lamp is reliably turned on.

Therefore, when the discharge lamp is preheated and lit using the above-described discharge lamp lighting device, the time from when the discharge lamp is turned on to when the operation of the dimming circuit is started becomes long. In particular, when the actual preheating time of the filament may be short, such as in summer when the ambient temperature is high, the dimming circuit does not operate immediately when the current flows through the discharge lamp, and the second timer described above is used. Since the operation of the dimming circuit is started when the time set by the circuit has elapsed, the time lag becomes very long.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and a discharge lamp lighting device capable of quickly adjusting light when the discharge lamp is turned on regardless of the environment around the discharge lamp. To provide.

[0007]

A discharge lamp lighting device according to the present invention comprises a switching element connected between a DC power supply and the discharge lamp, and a control drive for turning on and off the switching element to preheat and light the discharge lamp. A circuit, a dimming circuit that supplies a dimming signal to the control drive circuit to dimming the discharge lamp, and an ON signal that starts the discharge lamp after a predetermined time has elapsed since the DC power supply was turned on. It comprises a timer circuit that outputs to the drive circuit, and a reset circuit that detects that a certain amount of current is flowing through the discharge lamp and electrically connects the dimming circuit and the control drive circuit. is there.

[0008]

Next, an embodiment of a discharge lamp lighting device according to the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of a discharge lamp lighting device of the present invention connected between a DC power supply and a discharge lamp.

In this embodiment, a discharge lamp lighting device 1
Is a pair of switching elements 10a and 10b connected between the DC power supply 3 and the discharge lamp 2, and a control drive circuit 11 for preheating and lighting the discharge lamp 2 by alternately turning on these switching elements 10a and 10b. And a timer circuit 1 that outputs an ON signal to start the discharge lamp to the control drive circuit 11 after a predetermined time has elapsed after the dimming circuit 14 connected to the control drive circuit 11 and the DC power supply have been turned on.
5, a discharge lamp current detection circuit 17 that outputs a current signal while detecting that a current is flowing through the discharge lamp 2, and a reset circuit 1 that is connected to the discharge lamp current detection circuit 17.
And 8.

The dimming circuit 14 includes a control driving circuit 11
To control the discharge lamp 2. On the other hand, the reset circuit 18 electrically connects the dimming circuit 14 and the control drive circuit 11 only when a current signal of a certain value or more is output from the discharge lamp current detection circuit 17.

Diodes 19a and 19b are connected in parallel to the switching elements 10a and 10b, respectively. A capacitor 4 for blocking DC current and an inductor 5 are provided between the discharge lamp 2 and the switching elements 10a and 10b.
Are connected in series, and a resonance capacitor 2a is connected to the discharge lamp 2 in parallel.

Next, the operation of the discharge lamp lighting device 1 will be described with reference to a timing chart shown in FIG. 2 in which the discharge lamp is turned on earlier than the output signal of the timer circuit goes high. FIG. 2 shows an electric signal indicating the lighting state of the DC power supply 3, the timer circuit 15, and the discharge lamp 2 (in FIG. 2, simply described as "lighting of the discharge lamp 2"), the output of the current detection circuit 17 and the reset circuit 18. 3 shows a timing chart. The electric signal indicating the lighting state of the discharge lamp 2 becomes high level when the discharge lamp 2 is turned on.

First, when the DC power supply 3 is turned on, a voltage is applied to the discharge lamp 2, and after a predetermined time Δt 1 has elapsed, an ON signal for starting the discharge lamp is output from the timer circuit 15 to the control drive circuit 11. . The predetermined time Δt1 is a time required for preheating the filament, and is set in advance when designing the timer circuit 15.

When the preheating of the filament (not shown) of the discharge lamp 2 is completed and a current flows through the discharge lamp 2 and the discharge lamp 2 is turned on, the discharge lamp current detection circuit 17 detects that a current has flowed through the discharge lamp 2. Detect and output current signal. This current signal is output as long as the current is flowing through the discharge lamp 2. Note that FIG.
The middle time Δt2 is the time from when the DC power supply 3 is turned on to when the current actually flows through the discharge lamp 2 (actual filament preheating time). That is, the time Δt2 is
The length varies depending on the environment around the discharge lamp, such as being shorter in summer when the ambient temperature is high than in winter when the ambient temperature is low.

Next, when the current signal is output from the discharge lamp current detection circuit 17 to the reset circuit 18, conduction between the dimming circuit 14 and the control drive circuit 11 is established, and the current is output from the dimming circuit 14. The dimming signal is input to the control drive circuit 11 and dimming of the discharge lamp 2 is performed.

With such a configuration, the discharge lamp can be quickly turned on when the preheating of the filament is completed. Further, since the dimming is performed by immediately detecting that a current is flowing through the discharge lamp 2, the dimming can be quickly performed when the discharge lamp is turned on.

[0018]

As described above, according to the discharge lamp lighting device of the present invention, the discharge lamp can be quickly turned on, and the dimming can be quickly performed after the discharge lamp is turned on. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a discharge lamp lighting device of the present invention.

FIG. 2 is a timing chart showing the operation of the discharge lamp lighting device shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Discharge lamp lighting device 10a, 10b Switching element 11 Control drive circuit 14 Dimming circuit 15 Timer circuit 17 Discharge lamp current detection circuit 18 Reset circuit 2 Discharge lamp 3 DC power supply

Claims (1)

[Claims] 1. A switching element connected between a DC power supply and a discharge lamp, a control drive circuit for turning on and off the switching element to preheat and turn on the discharge lamp, and a dimming signal to the control drive circuit. A dimming circuit for dimming the discharge lamp, a timer circuit for outputting an ON signal for starting the discharge lamp to the control drive circuit after a predetermined time has elapsed since the DC power supply was turned on, and a timer circuit for turning on the timer circuit. When a signal is output, the discharge lamp is provided with a reset circuit that detects that a certain amount of current is flowing through the discharge lamp and electrically connects the dimming circuit and the control drive circuit. apparatus.