JPH02288198A - Discharge lamp lighting device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a discharge lamp lighting device, and particularly to a device for starting a mercury high-pressure discharge lamp such as a metal halide lamp (HID lamp) using an extremely simple circuit configuration. The present invention relates to a discharge lamp lighting device that can be operated accurately.

[Prior Art] Conventionally, in order to start a mercury high-pressure discharge lamp, when starting the lamp, that is, when transitioning from a glow discharge state to an arc discharge state, the discharge lamp is required to have a wave height larger than that during normal operation. Lighting was performed by applying a power source with a wide pulse width, heating the lamp electrodes with a large amount of energy, and emitting a large amount of thermoelectrons in a short period of time (Japanese Unexamined Patent Publication No. 1983-1999).
-72296). In other words, in such a conventional lighting device, by increasing the energy corresponding to the product of the peak value and pulse width of the pulse voltage applied to the discharge lamp when starting and restarting the discharge lamp, the lighting can be achieved relatively quickly. It was possible to start the discharge lamp immediately.

[Prior Art] However, in such a conventional discharge lamp lighting device, it is necessary to use an extremely complicated and large-scale circuit in order to generate power having a large peak value and pulse width when starting and restarting the lamp. This has the disadvantage of reducing the reliability of the device, increasing its size, and increasing its cost.

SUMMARY OF THE INVENTION An object of the present invention is to make it possible to appropriately light a discharge lamp such as a mercury high-pressure discharge lamp using an extremely simple circuit, in view of the problems in the conventional apparatus described above.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the discharge lamp lighting device according to the present invention includes an inverter means for generating a high frequency power source for lighting the discharge lamp, and an inverter means for generating a high frequency power source for lighting the discharge lamp. or a high voltage generating means for applying a high voltage to the discharge lamp at the time of restarting, a current control means for controlling the power supply current supplied to the inverter means, and a predetermined time period at the time of starting or restarting the discharge lamp. timer means are provided for controlling the current control output to increase the lamp current by the amount of the lamp current.

[Operation] In the above-described configuration, when the discharge lamp is started or restarted, the high voltage generating means operates to apply a narrow voltage with a large peak value to the discharge lamp. Further, the timer means operates to operate the current control means for a predetermined period of time, thereby increasing the power supply current supplied to the inverter means. That is, when starting and restarting the lamp, a voltage with a large peak value is applied to the discharge lamp to break the insulation within the lamp, and in this state, the lamp current is increased by the current control means to heat the electrodes. As a result, the thermoelectrons increase for a short period of time and the lamp is started properly.

[Example] Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows a lighting device for lighting a mercury high pressure discharge lamp such as a metal halide lamp according to an embodiment of the present invention. The device in the figure includes a DC power supply 1, a timer circuit having a capacitor 3, a diode 5, resistors 7 and 9, a transistor 11, and a relay coil 13a, a chopper circuit having a transistor 15 and a chopper control circuit 17, and a diode 19. a rectifying and smoothing circuit having a choke coil 21 and a smoothing capacitor 23; and a switching transistor 25.
．． 27.29.31, a current limiting transformer 35 connected in series with the discharge lamp 33 between the output terminals of the full bridge inverter circuit. It is composed of a high voltage generation circuit 37, a current control circuit connected between the chopper circuit and the inverter circuit, and having a resistor 39, 41 and a relay contact 13b. Note that the transistor 25. which constitutes the full bridge type inverter circuit.
27, 29, and 31 in a well-known manner are omitted for the purpose of simplifying the explanation.

In the device shown in FIG. 1, when the DC power supply 1 is turned on,
The chopper circuit 17 operates to turn on and off the transistor 15 at a frequency of, for example, several tens of kilohertz.

As a result, a high frequency AC power source is generated, and the diode 1
9 and smoothed by a choke coil 21 and a capacitor 23 to generate DC power, which is applied to the transistor bridge circuit of the inverter circuit. Among the transistors in the inverter circuit, transistors 25 and 31
The transistors 27 and 29 are turned on and off alternately, and a high frequency voltage is applied to the discharge lamp 33.

Further, in the timer circuit, immediately after the DC power supply 1 is turned on, the capacitor 3 is not yet charged, so the base voltage of the transistor 11 is at a high level. Therefore, the transistor 11 is turned on and the relay coil 1
3a is excited. Therefore, the relay contact 13b is closed, and a parallel circuit of the resistor 39 and the resistor 4 is connected to the negative power line between the chopper circuit and the inverter circuit. The voltage across this parallel resistance circuit is the chopper control circuit 1
7, and the duty of the switching signal supplied to the transistor 15 is increased so that the voltage across the transistor 15 becomes a predetermined value. As a result, the current supplied from the chopper circuit to the inverter circuit increases, and the lamp current increases. At this time, the high voltage generation circuit 37 is simultaneously activated by the action of the timer circuit, and a narrow voltage with a high peak value is continuously applied to the discharge lamp 33 for a predetermined period of time via the current limiting transformer 35. As a result, the insulation within the discharge lamp 33 is broken, the lamp current is increased by the chopper circuit in parentheses, a large amount of thermoelectrons are emitted from the lamp electrodes, and the lamp is started.

In the timer circuit, when the voltage across capacitor 3 gradually increases and reaches a predetermined value, transistor 11 is cut off and excitation of relay coil 13a is stopped. Therefore, the relay contact 13b opens and the resistor 41 connected in parallel with the resistor 39 is disconnected.

Therefore, since the voltage across the resistor 39 increases, the chopper control circuit 17 detects this and controls the on-time of the transistor I5 to be shortened. As a result, the current supplied from the chopper circuit to the inverter circuit is reduced, and normal constant current control is performed.

Specifically, the value of the resistor 39 is, for example, 0.1 ohm,
The value of the resistor 41 is, for example, 0.025 ohm.

During normal operation when the relay coil 13b is in an oven state, the current supplied from the chopper circuit to the inverter circuit is, for example, 3 amperes, whereas during startup when the relay contact 13b is closed, the current is supplied to the inverter circuit. The current is, for example, approximately 10 amperes. Further, the ON time of the relay contact 13b by the timer circuit is, for example, about 1 to 2 seconds.

[Effects of the Invention] As described above, according to the present invention, a voltage with a high peak value is applied to the discharge lamp by the high voltage generating circuit at the time of starting, and the lamp current is increased. It becomes possible to accurately start and restart discharge lamps such as high-pressure discharge lamps. Furthermore, since the high voltage generating means and the current control circuit are controlled by a common timer circuit, the circuit configuration is simplified, and the number of parts and the cost of the device can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing a schematic configuration of a discharge lamp lighting device according to an embodiment of the present invention. 1; DC power supply, 3.23: Capacitor, 5.19: Diode, 7.9, 39, 41: Resistor, 11, 15, 25, 27. 29. 31: Transistor, 13a: Relay coil, 13b: Relay contact , 17:
Chopper control circuit, 21: Choke coil, 33: Discharge lamp, 35: Current transformer, 37: High voltage generation circuit. Patent applicant: Toshiba Lightic Co., Ltd. Agent: Patent attorney Tetsuya Ito Agent: Yoshiaki Ikeuchi

Claims (1)

[Claims] an inverter means for generating a high frequency power source for lighting a discharge lamp; a high voltage generating means for applying a high voltage to the discharge lamp at the time of starting or restarting the discharge lamp; and a power supply current supplied to the inverter means. current control means for controlling;
Discharge lamp lighting characterized by comprising a timer means for operating the high voltage generating means for a predetermined time when starting or restarting the discharge lamp and also controlling the current control means so as to increase the lamp current. Device.