JPH04298993A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To provide d discharge lamp lighting device whereby shortening of a starting time and improvement of a rise up can be contrived. CONSTITUTION:In a discharge lamp FL, an output control part 8, which detects voltage of this discharge lamp FL to lower an output of a voltage dropping part 3 when the voltage of the discharge lamp FL is in a predetermined value or more, is connected. This output control part 8 is connected to a non-inversion input end of an operational amplifier OP through a resistor R1 from the discharge lamp FL and also connecting this non-inversion input end to a time constant circuit 11 constituted of a resistor R2 and a capacitor C1. Resistors R3, R4 are connected to an inversion input end of the operational amplifier OP to supply reference voltage to the inversion input end. Till a capacitor C11 of the time constant circuit 11 is charged, an input of voltage of the discharge lamp FL is stopped.

Description

[Detailed description of the invention]

[Object of the invention]

0002

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device for lighting a discharge lamp using, for example, high frequency.

0003

2. Description of the Related Art Conventionally, when lighting a discharge lamp, it is known that a large current is supplied to the discharge lamp at the time of starting, thereby shortening the starting time and improving the start-up time.

[0004] A device of this kind that increases the current to the discharge lamp during glow discharge immediately after starting and makes the current after arc discharge normal is disclosed, for example, in Japanese Patent Laid-Open No. 56-22.
It is described in JP-A No. 097, JP-A-57-892, JP-A-63-6788, and the like.

Furthermore, in order to make the light emission of the discharge lamp constant, there is also known a device that detects the voltage of the discharge lamp when the discharge lamp is turned on and makes the current supplied from the inverter to the discharge lamp constant.

[0006]

[Problem to be Solved by the Invention] However, when the current supplied to a discharge lamp is kept constant, the current is kept constant regardless of glow discharge or arc discharge immediately after starting, so the current cannot be increased. First, there is a problem in that it is not possible to shorten the starting time or improve the start-up time.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a discharge lamp lighting device that can maintain constant lighting of a discharge lamp under normal conditions, shorten starting time, and improve start-up time. With the goal.

[Configuration of the invention]

[0009]

[Means for Solving the Problems] A discharge lamp lighting device according to claim 1 detects a discharge lamp lit by the output of a power converter, and at least one of the voltage and current of the discharge lamp. In the discharge lamp lighting device including an output control section that controls the output of the power conversion section, the output control section does not perform detection for a predetermined period of time after the power conversion section is started.

A discharge lamp lighting device according to a second aspect of the present invention is the discharge lamp lighting device according to the first aspect, wherein the output control section includes comparison means for comparing a reference voltage and a voltage of the discharge lamp. At least one of the voltages of the discharge lamp is compared by the comparison means via a time constant circuit.

[0011]

[Function] In the discharge lamp lighting device according to claim 1, the output control section lights the discharge lamp with a large current without detecting the voltage or current of the discharge lamp for a predetermined period of time after starting the power conversion section, and after the predetermined period of time has elapsed, , detects the voltage or current of the discharge lamp to keep the output of the power converter constant, so that the lighting of the discharge lamp is kept constant during normal times, and the starting time is shortened and the start-up time is improved.

The discharge lamp lighting device according to claim 2 is the discharge lamp lighting device according to claim 1, in which at least one of the reference voltage of the output control section and the voltage of the discharge lamp is compared via a time constant circuit. By comparing , the predetermined time can be obtained with a simple configuration.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the discharge lamp lighting device of the present invention will be described below with reference to the drawings.

In the figure, 1 is a commercial AC power supply, and this commercial AC power supply 1 includes a smoothing rectifier 2 that smoothes and rectifies the commercial AC, a voltage step-down unit 3 that steps down the output from the smoother rectifier 2, and a voltage drop unit 3 that steps down the output from the smoothing rectifier 2. An inverter unit 4 as a power converter unit that converts the output of the step-down unit 3 into a high frequency is connected in cascade, and a discharge lamp FL such as a high-intensity discharge lamp is connected to the inverter unit 4.
is connected. Further, a starter 6 is connected to the discharge lamp FL to facilitate starting by outputting a high-voltage pulse etc. at the time of starting, and the inverter section 4 is connected to the discharge lamp FL.
A dimming control section 7 is connected to perform dimming by changing the output to L.

Furthermore, the discharge lamp FL detects at least one of the voltage or current of the discharge lamp FL,
An output control section 8 is connected that reduces or stops the output of the voltage step-down section 3 when at least one of the voltage and current of the discharge lamp FL is equal to or higher than a predetermined value. This output control section 8 is connected from the discharge lamp FL via a resistor R1 to a non-inverting input terminal of an operational amplifier OP serving as a comparator circuit, and is also connected to a time constant circuit 11 consisting of a resistor R2 and a capacitor C1. Furthermore, the inverting input terminal of the operational amplifier OP is connected to the connection point between the resistor R3 and the resistor R4 connected in series, and a reference voltage is supplied to the inverting input terminal. The output end of the operational amplifier OP is connected to the voltage step-down section 3.

Next, the operation of the circuit shown in FIG. 1 will be explained.

First, the commercial AC from the commercial AC power supply 1 is as follows:
The signal is smoothed and rectified by the smoothing rectifier 2, stepped down by the voltage step-down section 3, and oscillated at high frequency by the inverter section 4. Electric power is then supplied to the discharge lamp FL. When the discharge lamp FL starts, a pulse is output from the starter 6 to assist in starting the discharge lamp FL. Moreover, the capacitor C1 is
The discharge lamp FL is charged during a predetermined period of time when it is performing glow discharge, and as shown in FIG. 2(a), a voltage is input to the non-inverting input terminal of the operational amplifier OP.
As shown in FIG. 2(b), a voltage is input to the inverting input terminal, and a wide pulse, that is, a large current is supplied from the inverter section 4 to the discharge lamp FL. Then, as the discharge lamp FL shifts from glow discharge to arc discharge, the discharge lamp F
The current supplied to L decreases as shown in FIG. 2(c).

Therefore, when starting the discharge lamp FL, the voltage of the discharge lamp FL is not directly inputted to the operational amplifier OP by the time constant circuit 11, and the output control section 8 does not cause the voltage step-down section 3 to reduce the output. When starting the FL, a large current can be reliably supplied from the inverter section 4.
It is possible to shorten the starting time and improve the start-up characteristics.

After the discharge lamp FL is started and the time constant circuit 11 is charged, the output control section 8 detects the voltage or current of the discharge lamp FL, and when either of them rises above a predetermined value, The voltage step-down section 3 lowers or stops the output of the inverter section 4 to protect the inverter section 4 and the like.

Further, the output of the inverter section 4 can be controlled by the dimming control section 7 to dim the discharge lamp FL.

Next, another embodiment will be explained with reference to FIG. The circuit shown in FIG. 3 has a resistance R4 of the circuit shown in FIG.
A capacitor C2 is connected in parallel to the reference voltage, and a time constant circuit 12 is also provided on the inverting input terminal side which is the reference voltage.

According to the circuit shown in FIG. 3, FIG. 4(a)
Not only the voltage from the discharge lamp FL that is input to the non-inverting input terminal as shown in FIG. 4, but also the reference voltage that is input to the inverting input terminal with CR characteristics as shown in FIG. Since the inrush current shown by the broken line in FIG. 4(c) does not flow, the adverse effect on the inverter section 4 and the discharge lamp FL can be reduced.

Furthermore, it is also possible to remove the time constant circuit 11 from the circuit shown in FIG. 3 and use only the time constant circuit 12.

[0024] Furthermore, the power conversion section is not limited to an inverter section, but a chopper or the like may be used.

[0025]

[Effects of the Invention] According to the discharge lamp lighting device of the present invention,
By not performing detection for a predetermined period of time after the inverter starts, the output control unit can supply a large current to the discharge lamp when starting the discharge lamp, so it can keep the discharge lamp lit at a constant rate, shorten the starting time, and reduce the startup time. It is possible to improve the

Further, according to the discharge lamp lighting device according to the second aspect of the present invention, since the comparison circuit and the time constant circuit do not perform detection for a predetermined period of time, the configuration can be simplified.

[Brief explanation of the drawing]

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

FIG. 2 is a waveform diagram showing the same operation as above.

FIG. 3 is a circuit diagram showing an output control section of another embodiment of the same as above.

FIG. 4 is a waveform diagram showing the same operation as above.

[Explanation of symbols]

4 Inverter section 8 as a power conversion section
Output control section 11, 12 Time constant circuit FL Discharge lamp OP Operational amplifier

Claims (2)

[Claims] 1. A discharge lamp that is lit by the output of a power conversion section, and an output control section that detects at least one of the voltage and current of the discharge lamp and controls the output of the power conversion section. A discharge lamp lighting device, wherein the output control section does not perform detection for a predetermined period of time after starting the power conversion section. 2. The output control unit includes comparison means for comparing a reference voltage and a voltage of the discharge lamp, and the output control unit compares at least one of the reference voltage and the voltage of the discharge lamp with the voltage of the discharge lamp via a time constant circuit. The discharge lamp lighting device according to claim 1, wherein the discharge lamp lighting device is compared with: