JPS59180993A - Device for firing discharge lamp - 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 (Field of the Invention) The present invention relates to a discharge lamp lighting device capable of starting and lighting a discharge lamp without separately providing a starting pulse generating circuit and a step-up transformer type ballast.

(Background of the Invention) A device having the configuration shown in FIG. 1 is conventionally known as this type of device. In the figure, 1 is an AC power source such as a commercial power source, 2 is
is a step-up transformer type ballast, 3 is a discharge lamp (lamp), 4 is a
is the starting pulse circuit.

Generally, a discharge lamp requires a high voltage pulse of several hundred volts to several kilovolts when starting. In addition, the lamp voltage after startup changes as shown in Figure 2, but in the discharge lamp lighting device shown in Figure 1, the current is limited by the ballast 2, so the short circuit current in the glow discharge state is reduced. is sufficient and also stabilizer 2
Due to the desire for miniaturization, the voltage at the voltage rise portion when transitioning from the glow discharge state to the arc discharge state has been set to a low voltage close to the limit. In this way, in the conventional discharge lamp, the starting pulse generation circuit 4iP3 and the booster i~
A lance-type ballast 2 is required, which increases the size of the device, and because the input voltage and current-limiting inductance are constant, the short-circuit current in the glow discharge state is insufficient. If the device is made smaller, there are disadvantages such as difficulty in smoothly transitioning from the glow discharge state to the arc discharge state.

(Object of the Invention) The present invention has been made in view of the problems of the conventional type described above, and provides a discharge lamp lighting device that has a simple and compact configuration and is capable of supplying sufficient voltage and current at the time of starting. The purpose is to provide.

(Structure of the Invention) In order to achieve the above object, in the present invention, a first open circuit (main circuit) including an AC power source, a discharge lamp lit by the AC power source, and an inductor is formed, and the AC power source and a switch device forming a second closed circuit together with the inductor, and the switch device is turned on for a predetermined period in the first half of the half cycle of the AC power supply, and the second closed circuit is formed during this on period. A discharge lamp lighting device that stores energy in an inductor, and during a subsequent off period of the switch device, superimposes the stored energy on the AC power source and applies it to the discharge lamp before arcing, the device comprising: The on-period is switched to a longer time when the discharge lamp is started than when it is normally lit.

<Explanation of Examples) Hereinafter, the present invention will be described in detail using the drawings.

Incidentally, parts that are common or correspond to the conventional example are expressed by the same seasonal month.

FIG. 3 shows a circuit configuration of a discharge lamp lighting device according to an embodiment of the present invention. The discharge lamp lighting device shown in the figure is an AC 11Pi
One end of the inductor 2 is connected to one terminal a of the inductor 2, and a discharge lamp 3 is connected between the other end C of the inductor 2 and the other terminal of the AC power source 1, and the middle tap d of the inductor 2 is connected to the AC power source 1. A switching device 6 is connected between the power supply 1 and the b terminal. This constitutes a first open circuit (main circuit) consisting of the AC power supply 1, the inductor 2, and the discharge lamp 3.

The switch device 6 includes a diode bridge 11, a transistor 12, a current transformer (C, T, >13, a voltage sensing element (for example, 5B5) 14, a phase determining circuit 15, a lamp current detecting circuit 16, a resistor 17, 18, etc. , by turning on the AC power supply 1 for a predetermined period in the first half of each half cycle, a second closed circuit is formed together with the AC power supply 1 and the inductor 2.

The lamp current detection circuit 16 includes a current transformer (C, T,) 161
, a diode 162 and a capacitor 163 are installed, and the lamp current is detected by the primary winding of the current transformer 161.
The secondary winding induced voltage of this current transformer 161 is transferred to the diode 16.
2 and a capacitor 163 for rectification and smoothing to generate a voltage proportional to the lamp current.

The phase determining circuit 15 includes transistors 151, 152 a3
and resistors 153 and 154, and the secondary winding 132 of the current transformer 13 is connected in accordance with the output from the lamp current detection circuit 16.
The terminal resistance value R2 of Rc/Ro etc. is Rc (however, Rc
.

RO is the resistance value of the resistors 153 and 154, respectively). As a result, the equivalent resistance +a R1 of the primary winding 131 of the current transformer 13 changes, and the transistor 1
When the transistor 2 is turned on, the voltage between the collector and emitter of the transistor 12 and the current transformer 13 changes, and the output voltage curve between the DC terminal and therefore the AC terminal of the diode bridge 11 changes. In FIG. 4, a indicates a half-cycle output waveform of the AC power supply 1, and b indicates the output voltage between DC terminals.

The voltage sensitive element 14 turns on (breaks down) when the terminal voltage exceeds a certain voltage. As a result, the transistor 12 is turned off when the voltage between the DC terminals of the diode bridge 11 reaches a predetermined value.

Next, the operation of the discharge lamp lighting device shown in FIG. 4 will be explained.

In the first half of the half cycle of the AC voltage (FIG. 4a), when the pulsating output generated at the DC terminal of the diode bridge 11 rises from O to the base-emitter ON voltage V beo of the transistor 12, the transistor 12 becomes a resistor. 17
A pace current is supplied through 18 and 18 to turn on, and between the DC terminals of the diode bridge 11 and between the AC terminals there is a minute current calculated by converting the terminating resistance R2 of the secondary winding 132 of the current transformer 13 to the primary winding side. It is short-circuited by the resistor R1. As a result, AC power supply 1, part of inductor 2 (intermediate tap C
) and this resistor R1 form a second open circuit, and current flows into the inductor 2 from the AC power supply 1,
Between the DC terminals of the diode bridge 11, that is, the resistance R1
A voltage Vd determined by the inductance L between the terminals a and C of the inductor 2, the time constant L/R1 due to the resistor R1, and the AC voltage (instantaneous value) is generated across the series circuit of the transistor 12 and the transistor 12 (Fig. 4b). ). When this voltage Vd reaches a predetermined value and the constant voltage sensing element 14 breaks down, the pace current is cut off and the transistor 12 is turned off. That is, in this switch device 6, the AC power supply voltage is equal to the base-emitter ON voltage V be of the transistor 12.
It turns on at substantially 0 phase when the phase reaches o, and the phase determining circuit 1
The current transformer 13 is turned off at a phase angle φ that is controlled by varying the resistance value R2 at 5, that is, the primary equivalent resistance value R1 of the current transformer 13.

In the inductor 2, energy is stored by the current flowing through the second closed circuit when the switch device 6 is turned on, and during the subsequent off period of the transistor 12, that is, one switch device 6, the energy stored in the previous on period is transferred to the alternating current. It is superimposed on the power supply and supplied to the discharge lamp 3.

The voltage applied to the discharge lamp 3 is shown in FIG. 4C.

In the figure, a shaded area A indicates the energy accumulated in the inductor 2 during the on period of the transistor 12, and the accumulated energy represented by the area of this shaded area A is compared with the area of the shaded area A during the subsequent off period of the transistor 12, i.e. It is emitted as a pulse from the input line B with equal energy. In this case, the transistor 12 whose on period is longer is the discharge lamp 3.
The peak voltage and area (power) applied to the area are both human.

When starting the discharge lamp 3, in the lamp current detection circuit 16,
The lamp current flowing through the primary winding of the current transformer 161, that is, the lamp power, is zero, and the secondary winding output of the current transformer 161, and therefore the current detection output, is also zero. Therefore, the phase determining circuit 1
5, the transistor 151 is off, the transistor 152 is on, and the terminating resistor R2 is Ro/Rc. As a result, the primary conversion resistance R1 of the current transformer 13 becomes the minimum, and the rise of the voltage between the DC output terminals of the diode bridge 11, that is, the voltage applied to the voltage sensing element 14, is delayed the most. Therefore, at this time, the breakdown phase of the voltage sensitive element 4, that is, the off phase of the transistor 12 φ
By setting the operating voltage of the voltage sensing element 14, the values of the resistor 17.18 and the resistors 153.1, 54, etc. so that It is possible to generate pulses with a higher voltage than the discharge lamp starting voltage with superimposed energy.

Further, when the lamp current exceeds a predetermined value after the discharge lamp 3 is started, lighting of the lamp is detected, and the phase determining circuit 15 turns on the transistor 151 in accordance with the lamp current detection output of the lamp current detection circuit 16. I~Ran resistor 152
is turned off, and the secondary side terminating resistor R2 of the current transformer 12 is switched to RO. As a result, the curve of the voltage Vd between the DC output terminals of the diode bridge 11 is switched to the one with a shorter time constant, and as this voltage \/d rises rapidly, the voltage sensing element 14 is immediately turned on and the transistor 1 -2
turns off (phase φ).

In the above description, lamp lighting is detected by lamp current, but it may also be detected by lamp voltage, power, brightness, temperature, etc.

(Effects of the Invention) As described above, according to the present invention, the on period of the switch device is lengthened when supplying a starting pulse at the time of starting and when supplying a short circuit current in a glow discharge state. Dotted line in Figure 5 for those who do not switch the period)
As the voltage of the starting pulse becomes higher than that of the short-circuit type 1 (section A in Figure 5),
The flow supply port is increased (section B in the same figure), and when the lamp is started, the transition from the glow discharge state to the arc discharge state is performed smoothly, and the device configuration is improved because the step-up transformer J5 and the starting pulse circuit are not used. It is possible to simplify the process and downsize the device.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a conventional discharge lamp lighting device. FIG. 2 is a graph showing the lamp voltage VL versus the elapsed time after starting the discharge lamp in FIG. 1. FIG. A circuit configuration diagram of the discharge lamp lighting device, FIG. 4 is a voltage or current waveform diagram for each voltage or current waveform in the device shown in FIG. 3, and FIG. 5 is a characteristic of lamp voltage VL versus lamp current IL of the discharge lamp in the device shown in FIG. This is a graph showing. DESCRIPTION OF SYMBOLS 1... AC power supply, 2... Inductor, 3... Discharge lamp, 6... Switch device, 11... Diode bridge, 12... Transistor, 13... Current transformer, 1
4... Constant voltage sensing element, 15... Phase determining circuit, 1
6...Lamp current detection circuit. Patent applicant: Toshiba Denkiku Co., Ltd. Agent Patent attorney Tatsuo Ito Agent Patent attorney Tetsuya Ito Figure 1 Figure 2 Figure 20

Claims (1)

[Claims] 1. An AC power source, an inductance device, and a discharge lamp that forms a first open circuit together with the AC power source and the inductance device; a switch device forming a second open circuit together with an inductance device, the second open circuit stores energy in the inductance device, and during a subsequent period of the switch device, the stored energy key is transferred to the alternating current. A discharge lamp lighting device that applies an electric current to the discharge lamp before re-ignition in a superimposed manner on a power supply, characterized in that when the discharge lamp is started, the on-time of the switch device is switched to make it longer than during steady lighting. discharge lamp lighting device.