JPH04160796A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To prevent unexpected extinction of the arc discharge by causing an energy to be accumulated in a coil by an electric current flowing during the arc-discharge operation, and causing continuous flow of the electric current by the energy accumulated in the coil before unexpected extinction of the arc discharge. CONSTITUTION:A switch element 7 is turned on or off through operation of a drive circuit 13. At the time of 'on', the electric current from a power source 1 passes through a second coil 8 to thereby electrically charge a capacitor 10, and simultaneously passes through a first coil 4 and a starter circuit 5 to flow into a discharge lamp 6. In this way, power is supplied to the discharge lamp 6. Further, at the time of 'off', during a time period up to the next 'on' operation, the energy accumulated in the second coil 8 causes continuous flow of the electric current by way of a diode 9 and the first coil 4. When this energy is used up, the electric charge in the capacitor 10 causes continuous flow thereof via the first coil 4. Thus, the discharge lamp 6 is lit by being supplied with a direct current. Thus, the energy accumulated in the first coil 4 causes continuous flow of the electric current, to thereby prevent unexpected extinction of the arc discharge.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to improvements in discharge lamp lighting devices.

(Prior Art) A discharge lamp lighting device is known in which a discharge lamp is connected to a main power circuit via a starting circuit, the starting circuit starts lighting the lamp, and after lighting, the main power circuit maintains the lighting.

(Problem to be Solved by the Invention) In such a discharge lamp lighting device, the discharge lamp transitions from glow discharge to arc discharge at the time of startup, but the arc discharge is not necessarily maintained stably, and the electrode state There was a problem that the power supply would disappear due to instability.

SUMMARY OF THE INVENTION An object of the present invention is to provide a discharge lamp lighting device that prevents arc discharge from going out and starts and lights a discharge lamp stably.

[Structure of the Invention] (Means for Solving the Problems) The present invention connects in series a main power supply circuit for lighting and maintaining a discharge lamp, a coil, and a starting circuit for starting and lighting the discharge lamp.

(Function) In the present invention having such a configuration, the discharge lamp is started by the starting circuit, and kept lit, that is, arc discharged, by the main power supply circuit. Energy is stored in the coil by the current flowing during arc discharge. When the arc discharge is about to go out, the energy stored in the coil acts to keep the current flowing and prevents the arc discharge from going out.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, a control circuit 2 is connected to a power supply 1 to form a main power supply circuit 3. A starting circuit 5 is connected to the main power supply circuit 3 via a first coil 4, and a discharge lamp 6 is connected to the starting circuit 5.

The control circuit 2 is a type of step-down chopper consisting of a switching element 7 made of a transistor or the like, a second coil 8, a diode 9, and a capacitor 10. One end of the switching element 7 is connected to one end of the power supply 1, and the other end is connected to one end of the power supply 1. It is connected to one end of the second coil 8 and the cathode of the diode 9.

The other end of the second coil 8 is connected to one end of the first coil 4 and also to one end of the capacitor 10.

The other end of the first coil 4 is connected to one end of the starting circuit 5.

The anode of the diode 9 and the other end of the capacitor 10 are connected to the other end of the power source 1 via a controlled object detection means 11 composed of a resistor or the like, which detects controlled objects such as discharge current of the discharge lamp 6 and power consumption. It is connected to the other end of the starting circuit 5.

An integrating circuit 12 calculates the voltage across the controlled object detection means 11.
The averaged signal is then supplied to the drive circuit 13. The driving circuit 13 is also supplied with a constant control reference voltage from a control reference generating means 14.

The drive circuit 13 compares the average voltage obtained from the integration circuit 12 with the control reference voltage from the control reference generation means 14, and controls the switch so that the average voltage has a constant relationship with the control reference voltage. The duty cycle for turning on and off the element 7 is pulse-modulated.

In this embodiment with such a configuration, the switch element 7
is turned on and off by the drive circuit 13. When on, the current from the power source 1 flows through the second coil 8, charges the capacitor 10, and passes through the first coil 4 and starting circuit 5 to start the discharge lamp. It flows to 6. In this way, power is supplied to the discharge lamp 6.

Also, when it is off, the second coil 8
The energy stored in the capacitor 10 causes a current to continue to flow through the diode 9 and the first coil 4, and when this energy is exhausted, the electric charge in the capacitor 10 causes the current to continue to flow through the first coil 4.

In this way, the discharge lamp 6 is lit with direct current.

The current flowing through the controlled object detection means 11 is caused by the switching element 7
The voltage generated across the controlled object detection means 11 by this current is averaged by the integrating circuit 12 and input to the drive circuit 13.

In the drive circuit 13, the control reference voltage and the average voltage are compared,
The on/off duty cycle of the switching element 7 is pulse-modulated so that the average voltage maintains a constant relationship with the control reference voltage, that is, the average voltage is kept constant.

For example, if the controlled object detection means 11 is composed of a resistor, the average voltage becomes the average input current to the chopper, and this input average current is made constant.

When the voltage of power supply 1 is made constant, the input power is made constant,
Therefore, the output power, ie, the discharge lamp lighting power, remains approximately constant.

In this device, when the discharge lamp 6 shifts to arc discharge, arc discharge current flows through the first coil 4 and energy is stored. When the arc discharge of the discharge lamp 6 is about to go out at the time of starting the lamp, the energy stored in the first coil acts to keep the current flowing, thereby preventing the arc discharge from going out.

In this way, the discharge lamp 6 is stably started and lit, and eventually enters a steady lighting state.

Next, other embodiments of the present invention will be described with reference to the drawings. It should be noted that the same parts as in the previous embodiment are given the same reference numerals and detailed explanations will be omitted.

As shown in FIG. 2, this has a first coil 4 inserted in series between a starting circuit 5 and a discharge lamp 6.

Even in this case, the same effects as in the embodiment described above can be obtained.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide a discharge lamp lighting device that prevents arc discharge from going out and starts and lights a discharge lamp stably.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing one embodiment of the invention, and FIG. 2 is a circuit diagram showing another embodiment of the invention. 3... Main control circuit, 4... First coil, 5... Starting circuit, 6... Discharge lamp. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] A discharge lamp lighting device that has a main power supply circuit that keeps the discharge lamp lit, a coil, and a starting circuit that starts and lights the discharge lamp connected in series.