JPH01294399A - Electric discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To permit lighting of a lamp with one type serving as plural types and also an adjusted lighting of a lamp in a plural-phased brightness without an exclusive dimmer by providing a switching means which switches detection gains in load current detecting circuit. CONSTITUTION:A switching means 8 is provided, which is adapted to detect load current and to switch detection gains. When a lamp FL is not turned on, therefore, load voltage is high and load current is weak, on account of which is load voltage V1 is fed back as a logical OR voltage to control output so that this load voltage V1 can be constant. Meanwhile, when the lamp FL is turned on, the load current is strong and the load voltage is low, on account of which a detected voltage V2 of the load current is fed back as a logical OR voltage to control output so that the load current can be constant. Lamp current is thus made into a constant current to light the lamp FL in an almost constant brightness. Additionally the switching means 8 permits the value of the lamp current to be switched easily and one stabilizer to be shared with a different rating lamp.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a discharge lamp lighting device that controls output based on both load voltage and load current, and particularly to a discharge lamp lighting device that controls output based on both load voltage and load current. The present invention relates to a discharge lamp lighting device that can light a plurality of types (ratings) of lamps at appropriate brightness.

[Prior Art] Conventionally, a discharge lamp lighting device (electronic ballast) for lighting a discharge lamp (lamp) such as a fluorescent lamp has been used to
(110W, etc.) required a different ballast. Also, even if the lighting equipment uses the same type of lamp, for example, when the bottom side is open, the lamp will be lit at 100% brightness, and when a louver is attached, the lamp will be turned on to obtain the same brightness as when the bottom side is open. Conventionally, when dimming a lamp such as lighting it at 150% brightness, a dedicated dimmer was required.

[Problems to be Solved by the Invention] The present invention is capable of lighting multiple types (ratings) of lamps with one type, and also allows the lamp to be dimmed and lit in multiple levels of brightness without a dedicated dimmer. The purpose of the present invention is to provide a discharge lamp lighting device that is capable of

[Means for Solving the Problems] In order to solve the above problems, the present invention detects a load voltage and a load current, and feeds back a logical OR voltage of the detected voltage of the load voltage and the detected voltage of the load current. The discharge lamp lighting device for controlling the load voltage and load current is provided with a switch means for switching a detection gain for detecting the load current.

[Function] According to the present invention having the above configuration, when the lamp is not lit, the load voltage is large and the load current is small, so the load voltage is fed back as the voltage of the logical sum,
The output is controlled so that this load voltage is constant. This limits the voltage applied to each circuit element when starting the lamp, and therefore requires less margin for each circuit element, making it possible to construct the device in a compact and inexpensive manner. . On the other hand, when the lamp is lit, the load current is large and the load voltage is small, so the detected voltage of the load current is fed back as the logical sum voltage, and the output is controlled so that the load current is constant. As a result, the lamp current is made constant, and the lamp is lit at approximately constant brightness. The output characteristic curve of this discharge lamp lighting device, which controls the output as described above, is rectangular as shown in FIG. If the switch means is changed to increase the output current detection gain, the output current will become smaller as shown by the dotted line A in Figure 2, and if the detection gain is lowered, the output current will be reduced as shown by the solid line B in Figure 2. becomes bigger. Therefore, when the lamp is turned on, the lamp current and brightness are determined by this detection gain.

[Explanation of Examples] Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 shows a circuit diagram of a discharge lamp lighting device according to an embodiment of the present invention. The device shown in the figure converts an AC input from an AC power supply 1 into DC through a rectifying and smoothing circuit 2, and from this DC output, outputs a high frequency output generated by an inverter 3 to a discharge lamp (lamp) FL, such as a firefly. By supplying light to the lamp, the lamp FL is lit.

In the figure, inverter 3 is a so-called half-bridge type separately excited inverter (separately excited series inverter).
5EPP (single-ended,
push-pull) connected field effect transistor (MO
SFET) Ql, Q2 and these transistors Q1
．． 02, a connection point J1 between transistors Q1 and Q2, and a DC output terminal a of the rectifying and smoothing circuit 2.

The primary winding Wp of the output transformer T1 is connected in an alternating current manner between the output transformer T1 and the output transformer T1, and the lamp FL, which is a load, is connected to the secondary winding Ws of the output transformer T1. Capacitor CO, C7
is a DC blocking capacitor. Also, output lancer T
1 includes a filament heating winding Wf'l of the lamp FL.
, Wf'2 and a lamp voltage detection winding Wd. Further, a resonance capacitor C8 is connected in parallel to the secondary winding Ws of the output transformer T1.

The load voltage detection circuit 6 rectifies, smooths, and divides the high frequency voltage induced in the lamp voltage detection winding Wd of the output transformer T1 to generate a detection voltage v1 proportional to the lamp voltage.

The load current detection circuit 7 rectifies, smoothes, and divides the high frequency voltage induced in the secondary winding of the current transformer CT for lamp current detection of the lamp FL to generate a detection voltage V2 proportional to the lamp current.

The output voltages Vl, V2 of these detection circuits 6.7 are connected to diodes D91. The higher voltage is selected by the OR circuit 91 consisting of D92 and supplied to the output control circuit 4.

The output control circuit 4 generates a pulse whose frequency changes according to the input voltage from the OR circuit 9, and drives the transistors Q1 and Q2 so that there is no period in which they are simultaneously turned on. As such an output control circuit 4, a VCO (voltage controlled oscillator) can be used. In addition, commercially available I
C such as TL494 or M83759 may be used.

As described above, the resonance capacitor C8 is connected in parallel to the secondary winding Ws of the output transformer T1. For this reason, transistor Q1. When the on/off frequency of Q2 approaches the resonant frequency caused by the inductance of the secondary winding Ws of the output transformer T1 and the capacitance of the resonance capacitor C8, the voltage induced in the secondary winding Ws increases, and the lamp voltage increases. and the current increases. Furthermore, if the on/off frequencies of the transistors Ql and Q2 deviate from the resonant frequency, the voltage induced in the secondary winding Ws becomes lower, and the lamp voltage and current decrease. therefore,
By varying the on/off frequencies of transistors Ql and Q2, lamp voltage and current can be controlled.

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

When AC power supply 1 is turned on in the device shown in FIG. 1, a DC voltage is output from rectifying and smoothing circuit 2 and applied to a series circuit of transistors Ql and Q2 of inverter 3. Also, the output control circuit 4 starts operating and the transistor Q1
and drives the gate of Q2. As a result, the inverter 3 is activated and a high frequency output whose frequency is controlled by the output control circuit 4 is generated at the output terminal Jl of the inverter 3.

First, by the operation of a soft start circuit (not shown), the load (lamp) voltage is set so that the voltage applied to the lamp FL does not reach the discharge starting voltage of the lamp FL.

Immediately after the power is turned on, the lamp FL has not reached the dischargeable state, so the secondary winding Ws of the output transformer Tl is in an open load state. Therefore, a voltage higher than that during normal lighting is induced in each winding of the output transformer T1. As a result, the filament of the lamp FL is supplied with a relatively large current and is preheated. In this case, although a detection voltage V1 corresponding to the induced voltage of the detection winding Wd is generated in the load voltage detection circuit 6, the output voltage v2 of the load current detection circuit 7 is substantially zero. Therefore, in this case, the output control circuit 4 receives the detection voltage ■1 outputted from the load voltage detection circuit 6, and controls the transistor Ql so that this load voltage (lamp voltage) becomes the voltage set above.
, Q2's on/off frequency is controlled.

When a predetermined period of time has passed after the power is turned on, the soft start is canceled and the load voltage is set to a voltage higher than the discharge start voltage of the lamp FL.

In response to this, the output control circuit 4 switches the output frequency of the inverter to be close to the resonant frequency. As a result, the voltage applied to the lamp FL exceeds the discharge starting voltage, and the lamp FL starts discharging. That is, the lamp FL
The discharge is suppressed until the filament is sufficiently preheated, preventing a cold start, and the lamp is turned on immediately after preheating.

When the lamp FL starts discharging, the lamp voltage decreases, so the output v1 of the load voltage detection circuit 6 decreases. On the other hand, since the lamp current flows, the output voltage V2 of the load current detection circuit 7 increases, and Vl<V2. As a result, in the OR circuit 9, the diode D91 is turned off and the diode 92 is turned on, and the load current detection circuit 7 is connected to the output control circuit 4.
The output voltage v2 of is inputted. therefore,
In this case, the output control circuit 4 receives the detection voltage V2 output from the load current detection circuit 7, and controls the transistors Ql and Q2 so that this load (lamp current) becomes a predetermined value.
The on/off frequency (output frequency of inverter 3) is controlled.

The switch circuit 8 is for switching the detection gain of the load current detection circuit 7, and for example, it is for switching the voltage division ratio for dividing the output of the current transformer CT. When this voltage division ratio is increased to lower the detection gain, the output voltage of the load current detection circuit 7 becomes lower for the same load current. therefore,
The load current is on the larger side, which is the side indicated by the solid line B in FIG. Furthermore, when the voltage division ratio is decreased to increase the detection gain, the output voltage of the load current detection circuit 7 becomes higher for the same load current. Therefore, the load current is on the small side, which is on the dotted line A in FIG.

Therefore, when this discharge lamp lighting device is applied as a high-output electronic ballast used in a lighting fixture with a removable louver, the brightness is 100% when the switch SW of the switch circuit 8 is turned off (higher detection gain). Switch SW on (
By setting the division ratio (detection gain) so that the brightness is 150% with the lower detection gain, when the bottom surface is open with the louver removed, the lamp can be turned off at 100% brightness by turning off the switch SW. When the lamp is lit and the louver is installed, the switch SW is turned on to turn on the lamp at 150% brightness, ensuring the same brightness as when the bottom surface is open. That is, the brightness can be adjusted in steps from 100% brightness to 150% brightness by simply turning the switch SW on and off.

Also, when the switch SW is off (higher detection gain), the load (
By setting the lamp) current to the rated current value of a 40W lamp and the load (lamp) current when the switch SW is on (lower detection gain) to the rated current value of a 110W lamp, when the switch SW is turned off, the load (lamp) current will be 40W. The lamp can be turned on, and by turning on the switch SW, the 110W lamp can be turned on. That is, one electronic ballast can be used in common for a 40W lamp and a 110W lamp.

FIG. 3 shows a circuit configuration of a discharge lamp lighting device according to another embodiment of the present invention. The device shown in the figure lights two lamps in series, and the AC input from the AC 242V AC power supply via the surge absorption circuit 11 and noise prevention circuit 12 is rectified by the full-wave rectifier circuit REI. , the DC output obtained by smoothing by the partial smoothing circuit 21 is 5E
PP) Run risk It is input to the series inverter 3 consisting of Ql and Q2, converted to high frequency output, and supplied to the series circuit of lamps FLI and FL2 via the output transformer T1 to light up. This device is similar to the device shown in FIG.

The partial smoothing circuit 21 controls capacitor C2, diode D3, . Capacitor C
3. Charge capacitors C2 and C3 in the path of resistor R33 and Cyrisk SCR to approximately 1/2 of the peak voltage of the pulsating output, and during a period when the voltage of the pulsating output is lower than, for example, 172 of the peak voltage. , capacitor C2
from the capacitor C via diodes Di and Die.
3 is supplied to the inverter 3 via diodes D1B and D2. This partial smoothing circuit 21 is
Since the valley portion of the output waveform, which is lower than about 1/2 of the peak voltage of the pulsating output, is filled with the discharged charges of the capacitors C2 and C3, it is also called a valley-filled smoothing circuit. By using such a partial smoothing circuit 21, this discharge lamp lighting device prevents the input power factor from decreasing as in the case of a capacitor input type, and maintains a high input power factor.
Lamp FLI eliminates the pause period of high frequency output.

FL2 is made to light up efficiently.

When the power is turned on, the thyristor SCR of the partial smoothing circuit 21
This is to prevent a rush current from flowing into the capacitors C2 and C3 with zero charge. In other words, since the thyristor SCR is off when the power is turned on, the capacitors C2 and C3
A resistor R39 is inserted in series with the charging circuit. Therefore, the AC power supply, full-wave rectifier circuit RE1, capacitor C2,
The current flowing through the path consisting of C3, diode D3, etc. is limited by resistor R39. In other words, when the power is turned on,
Inrush current flowing through the above path is prevented, and the full wave rectifier circuit R
Elements such as EI, capacitors C2, C3 and diode D3 are protected. When the inverter 3 starts operating and a high frequency voltage is induced in the control winding We of the output transformer T1, this high frequency voltage is rectified by the diode D6, smoothed by the capacitor C17, and passed through the resistor R3B to the gate of the cyrisk SCH. is applied to As a result, the thyristor SCR is turned on and the resistor R89 is short-circuited, and the series resistance of the charging path of the capacitors C2 and C3 is reduced to the minute R33.
The inrush current prevention operation is canceled.

The hybrid integrated circuit HIC is one in which all or the main parts of the output control circuit 4 shown in FIG. 1, the OR circuit 9, etc. are integrated.

Next, the operation of the apparatus shown in FIG. 3 will be explained.

When AC242V AC power is turned on, this AC24V
2V is input to the full-wave rectifier circuit REI via the surge absorption circuit 11 and the noise prevention circuit 12. The partial smoothing circuit 21 partially smoothes the pulsating output (rectified output) of the full-wave rectifier circuit REI and supplies the DC output to the inverter 3 and the HIC.
supply to.

Immediately after the power is turned on, the terminal voltage of the capacitor C13 of the soft start circuit 61 is 0, and the transistor Q4 is off. Therefore, the resistor R21 of the load voltage detection circuit 6
, R22, R29 and the variable resistor VVR is set to the low side. That is, the detection gain is high<high, and therefore the load voltage setting value is set to the lower side.

Here, the voltage applied to the lamp FLI is set to be lower than the discharge starting voltage of the lamp FL1.

Also, immediately after this power is turned on, the lamp FLI.

Since FL2 has not reached the dischargeable state, the secondary winding Ws of the output transformer T1 is in an open load state. Therefore, a voltage higher than that during normal lighting is induced in each winding of the output transformer Tl. As a result, each filament of the lamps FLI, FL2 is connected to each filament winding Wf1. W[2° A relatively large current is supplied from WF2 to preheat. In this case, although a detection voltage Vl corresponding to the induced voltage of the detection winding Wd is generated in the load voltage detection circuit 6, the output voltage V2 of the load current detection circuit 7 is substantially zero. Therefore, in this case, the output control circuit 4 outputs the detected voltage V output from the load voltage detection circuit 6.
l is input, and the on/off frequencies of the transistors Ql and Q2 are controlled so that this load voltage (lamp voltage) becomes the above-mentioned set voltage.

When the inverter 3 operates after the power is turned on, the output voltage T
A high frequency voltage is induced in the control winding We of 1, this high frequency voltage is rectified by the diode DB, and smoothed by the capacitor C17 to generate a DC voltage.

This DC voltage is applied to the gate of the thyristor SCR via the resistor R3B of the partial smoothing circuit 21 as described above,
The Cyrisk SCR turns on and cancels the inrush current prevention operation, and the resistor R24 of the soft start circuit 61
The capacitor C13 is charged via the capacitor C13. When this capacitor C13 is charged and its terminal voltage exceeds the zener voltage of the zener diode ZD2, the transistor Q4
is supplied with base current and turns on. As a result, the detection gain of the load voltage detection circuit 6 is switched to the lower side, the lamp voltage setting value is switched to the higher side, and the soft start operation is canceled.

Since the sequential capacitor C10 is connected in parallel to the lamp FL2, when both the lamps FLI and FL2 are off, substantially all of the induced voltage in the secondary winding Ws of the output transformer Tl is applied to the lamp FLI. be done. Therefore, when the soft start operation is canceled and the induced voltage of the secondary winding Ws becomes higher than the discharge starting voltage of the lamp FLI, the lamp FL1 starts discharging. Then, this time, capacitor CIO and lamp F
Since the impedance of the lamp FL1 is extremely low compared to L2, substantially all of the induced voltage of the secondary winding Ws is applied to the lamp FL2, and the lamp FL2 starts discharging (lighting up).

In this way, when the lamps FLI and FL2 start discharging one after another, the lamp voltage decreases, so the output v1 of the load voltage detection circuit 6 decreases. On the other hand, since the lamp current flows, the output voltage v2 of the load current detection circuit 7 that rectifies, smoothes, and divides the output of the current transformer CT increases, and Vl < V2
becomes. As a result, the OR circuit in the HIC selects the output voltage v2 of the load current detection circuit 7 and outputs it to the output control circuit 4.
Enter. Therefore, in this case, the output control circuit 4 detects that the load current is the resistance R19, R20 of the load current detection circuit 7.
Then, the transistors Ql and Q2 are turned on and off at a frequency set by a variable resistor IVR or the like.

The switch SW and the resistor R81 constitute a switch circuit 8 similar to that shown in FIG. The relationship between the state of the switch SW and the output characteristics or lamps used in the apparatus shown in FIG. 3 is as shown in the table below.

■ In the electronic ballast for 40W and 110W lamps in Fig. 3, the bidirectional trigger diode SBS of the load voltage detection circuit 6 stops the output of the inverter 3 during no load or when there is overpower at the end of the lamp life. It forms a safety circuit that protects the That is, when an abnormal voltage is induced in the detection winding Wd of the output transformer TI due to one-way discharge during no load or at the end of its life, the trigger diode SBS is turned on and the transistors Ql and Ql of the inverter 3 are turned on.
Prohibits generation of Q2 drive pulse signal. As a result, the output of the inverter 3 is stopped, and the circuit is protected.

[Effects] According to the present invention, the load (lamp) current when the lamp is turned on is made constant, and a switch means is provided for switching the load current value, so that it is possible to use, for example, a high-output electronic ballast. When using a lighting fixture with the bottom open, the lamp should be lit at 100% brightness, and
When the louver is attached and used, the brightness can be easily switched, such as lighting the lamp at 150% brightness. Further, even when using different lamps such as 40W and 110W, the lamp current value can be easily switched by a switch means attached to the ballast.

That is, one ballast can be shared by lamps with different ratings.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a discharge lamp lighting device according to an embodiment of the present invention, FIG. 2 is an output characteristic diagram of the device of FIG. 1, and FIG. 3 is a diagram of a discharge lamp lighting device according to another embodiment of the present invention. FIG. 2 is a circuit configuration diagram of such a discharge lamp lighting device. 1: AC power supply, 2: Rectifier smoothing circuit, 3: Inverter, 4: Output control circuit, 5: Load circuit, 6: Load voltage detection circuit, 7: Load current detection circuit, 8: Switch circuit, 9: OR circuit, SW: Switch.

Claims (1)

[Claims] 1. A load voltage detection circuit that detects a load voltage and generates a first detection voltage according to the load voltage, and a second detection circuit that detects a load current and generates a first detection voltage according to the load current. A discharge lamp lighting device comprising a load current detection circuit that generates a voltage, and an output control circuit that controls output to the load according to a logical sum of the first and second detected voltages, the load A discharge lamp lighting device comprising a switch means for switching the detection gain of a current detection circuit.