JPS6259439B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention applies to HID lamps such as mercury lamps and metal halide lamps.
This relates to a lighting device for a discharge lamp.It eliminates the power supply transformer, current detection transformer, and resistor to make the device smaller and lighter, and also reduces the amount of radiation caused by power supply distortion, voltage fluctuations, and variations in the characteristics of the discharge lamp. The first purpose is to control the lamp output to a substantially constant level, and the second purpose is to obtain stable starting characteristics.

The structure of the present invention will be explained in detail below with reference to embodiment figures.

FIG. 1 shows an embodiment of the present invention, in which an auxiliary choke L ₂ is connected between the AC power source E and the discharge lamp A.
A reference voltage generation circuit 1 generates a full-wave rectified voltage that is a certain phase ahead of the power supply voltage by connecting a triax S in parallel and a current limiting choke L1 in series.
, a lamp voltage detection circuit 2 that steps down and rectifies and smoothes the voltage across the discharge lamp A, a comparison circuit 3 that compares the output of the reference voltage generation circuit 1 and the output of the lamp voltage detection circuit 2, and the current limiting circuit L A lamp current detection circuit 6 which rectifies the induced voltage of the secondary winding provided in ₁ with a rectifier circuit B ₂ and smoothes it with a smoothing circuit consisting of a resistor R ₁₂ and a capacitor C ₂ to obtain a lamp current detection voltage Vc ₂ . , an diode D ₅ and a resistor for superimposing the rectified voltage of the lamp voltage detection circuit 2 on the lamp current detection voltage Vc ₂ of the lamp current detection circuit 6.
R ₂₁ and a Zener diode Z ₆ for making the lamp current detection voltage Vc ₂ a constant voltage.
Using the output of the constant voltage circuit as a power source, charging is started by the output of the comparison circuit 3, and the lamp current detection voltage Vc ₂ is divided by the voltage dividing resistors _{R 10} and R ₁₁ . The battery includes a CR timer 5 that starts discharging when the charging voltage reaches the divided voltage _V3 , and a pulse generating circuit 4 that generates a pulse that triggers the above-mentioned triax S using the discharge current of the CR timer 5. It is something that

To further explain the configuration of each part in detail, in the reference voltage generation circuit 1, the power supply voltage Vs is generated by the CR phase shift circuit.
A voltage with a certain phase lead is obtained from , and this is rectified by the full-wave rectifier circuit B3 to obtain V1 shown in FIG. 2B. In addition, in the lamp voltage detection circuit 2, a step-down transformer T
The secondary side voltage of 1 is rectified by the full-wave rectifier circuit B1 and smoothed to obtain the voltage V2. The output V1 of the reference voltage generation circuit 1 and the output V2 of the lamp voltage detection circuit 2 thus obtained are compared by a comparator circuit 3 consisting of a transistor Q1, diodes D1 and D2, and a resistor R3, and the moment V1 becomes lower than V2. At t1, transistor Q1 turns off, transistor Q2 turns off, transistor Q3 turns on, and transistor Q
4 are turned off, capacitor C3, which has been bypassed by transistor Q4, begins to be charged through resistor R9, and a timer operation is performed by the time constant of C3 and R9. When the voltage Vc3 of the capacitor C3 becomes equal to the divided voltage V3 of the output voltage Vc2 of the lamp current detection circuit 6, at time t2 in FIG. This discharge current generates a pulse on the secondary side of the pulse transformer T2, and a trigger pulse V4 is applied between the gate and cathode of the triac S through the diode D4, causing the triac S to fire. That is,
V3 in FIG. 2C becomes the discharge starting voltage of the time constant circuit of the timer.

Here, the function of the auxiliary choke _L2 will be explained. That is, the auxiliary chain _L2 is provided in order to continue to flow a minute current from the AC power supply E to the discharge lamp A through the auxiliary chain _L2 and the current limiting chain _L1 even while the triax S is turned off. This prevents an increase in the re-ignition voltage of the discharge lamp A, prevents the discharge lamp A from going out, and
This is to extend the life of the discharge lamp A. In addition, in the lamp current when the discharge lamp A is turned on, if there is no auxiliary station yoke _L2 , there will be a pause period, but with the auxiliary station yoke _L2 , current flows through the auxiliary station yoke _L2 . Therefore, there is no rest period, the peak of the lamp current decreases, and the luminous efficiency of the discharge lamp A increases. In addition, when the discharge lamp A is activated, the auxiliary station L ₂
If there is no , Triack S is off, so
No power supply voltage will be applied to discharge lamp A, and discharge lamp A will not start. Therefore, immediately before starting, no current is flowing through discharge lamp A, so the auxiliary choke
Due to the presence of _L2 , the power supply voltage is applied to the discharge lamp A as is. Since this voltage is higher than the starting voltage of discharge lamp A, discharge lamp A is started. When the discharge lamp A starts, the circuit for controlling the phase of the triax S operates, so the triax S turns on and off, causing current to flow.

In the above configuration, if we consider a case where the power supply voltage fluctuates and the current flowing into the discharge lamp A decreases after the discharge lamp reaches steady lighting, the voltage induced on the primary side of the current limiting choke L1 2, the voltage Vc2 after rectification and smoothing decreases, and the discharge starting voltage _V3 of the timer time constant circuits C3 and R9 decreases, causing the firing phase t2 in Fig. 2 to shift to the left, resulting in a trial start. The trigger pulse V4 to S is applied early, and works in the direction of increasing the current of discharge lamp A. Conversely, if the current of the discharge lamp A increases above the rated value, the lamp current will be suppressed in the same manner as described above. In addition, in response to fluctuations in lamp voltage, a comparator circuit 3 compares the output V2 of the lamp voltage detection circuit 2 and the reference voltage V1, and controls the charging start phase of the time constant circuit of the timer, that is, t1 in FIG. 2. .

The above are explanatory diagrams of the basic constituent parts of the invention. Conventional examples of this basic component include, for example, as shown in FIG. As shown in FIG. 4, there is a constant voltage control system in which the lamp current detection circuit 6 is removed from the basic configuration circuit of the present invention. However, these conventional examples do not control the power at a constant level, so in the case shown in Figure 3, for example, even if the discharge lamp voltage becomes high, it cannot be detected, and the output increases, which may cause the discharge lamp to explode or shorten its life. Moreover, there are problems such as power loss in the resistor R' and heat generated thereby, increase in size due to the transformer T', and increase in cost. In addition, in the case of Fig. 4, the triax S
Since the firing angle of increases with the increase in lamp voltage,
After all, the output increases, resulting in the same drawback as shown in Figure 3.Also, when harmonic components are superimposed on the power supply, the impedance of the yoke L1 changes, causing the lamp current to fluctuate, resulting in an overload. easy.

According to the basic configuration circuit of the present invention, it is possible to detect not only changes in the lamp voltage but also changes in the current flowing into the lamp and provide feedback to the pulse circuit for control. It has the advantage that a constant amount of power can always be supplied to the lamp, regardless of the characteristics of the discharge lamp.

Next, the characteristic features of the present invention will be explained with reference to FIG. It is superimposed on the rectified and smoothed voltage Vc2 of the circuit 6, that is, the lamp current detection voltage, and the lamp current detection voltage
Constant voltage circuit that inputs Vc2, that is, resistor R1
3 and a Zener diode Z6, and this constant voltage circuit is used as a power source for the pulse generating circuit 4.

In the above configuration, if you turn on the power now,
A weak current, or dark current, flows through the discharge lamp A through the current-limiting choke L1 and the auxiliary choke L2, but the voltage across the lamp does not drop completely with this level of current, and becomes about the same level as the power supply voltage, or about half of it. There is. Therefore, the voltage V5 obtained by stepping down this lamp voltage by the transformer T1 and rectifying it by the rectifier circuit B1 is a voltage that can sufficiently drive the pulse generating circuit 4. In actual value, the power supply voltage
200V, mercury lamp dark current 0.5A, lamp voltage is
It is about 130V, and the secondary voltage of transformer 1 is about
25V, and the Zener voltage of constant voltage circuit Z6 is 15V. Therefore, this is connected to diode D5 and resistor R2.
1 to capacitor C2 through
The pulse generating circuit 4 can be driven to generate a trigger pulse to ignite the triac S and start the lamp A. When the lamp is completely started, the lamp voltage becomes low, and on the other hand, the voltage induced in the secondary winding of the current limiting choke L1 becomes large, so that the pulse generating circuit 4 can be driven by this voltage. At this time, V5 also
The voltage drops to about 10V, which is lower than VVc2, and diode D5 prevents reverse current, so
The DC circuit 7 has a function of separating the lamp voltage detection circuit 2 and the lamp current detection circuit 6 during steady lighting, and therefore does not affect other control characteristics.

Even without this DC circuit 7 in the circuit of FIG. 1, a voltage is induced in the secondary winding of the current limiting choke L1 by the dark current of the lamp when the power is turned on.
This drives the pulse generation circuit and starts the lamp, but some discharge lamps have a very small dark current, and the same lamp also has a small dark current in cold weather, so it is difficult to start the lamp reliably. Conventionally, the power supply voltage was stepped down using a transformer as shown in Figure 4, or divided using resistors and added to the pulse generation circuit, but this method requires a transformer or has a large capacity. It was uneconomical as it required resistance.

As described above, the present invention generates a reference voltage by connecting a triax with an auxiliary choke connected in parallel and a current limiting choke in series between an AC power supply and a discharge lamp to generate a full-wave rectified voltage that is a certain phase ahead of the power supply voltage. a lamp voltage detection circuit that steps down the voltage across the discharge lamp to rectify and smooth it; a comparison circuit that compares the output of the reference voltage generation circuit with the output of the lamp voltage detection circuit; A lamp current detection circuit that rectifies and smoothes the induced voltage of the next winding to obtain a lamp current detection voltage, and a diode and a resistor that superimposes the rectified voltage of the lamp voltage detection circuit on the lamp current detection voltage of the lamp current detection circuit. a series circuit consisting of a series circuit, a constant voltage circuit that makes the lamp current detection voltage a constant voltage, and a constant voltage circuit that uses the output of the voltage circuit as a power source and starts charging with the output of the comparator circuit, and a voltage that is obtained by dividing the lamp current detection voltage. It is equipped with a CR timer that starts discharging when the charging voltage reaches the piezoelectric voltage, and a pulse generation circuit that generates a pulse that triggers the above-mentioned tri-attack using the discharge current of this CR timer. By using the input constant voltage circuit as the power source for the CR timer, the reference voltage generation circuit, which was conventionally configured with a transformer, can be changed to a reference voltage generation circuit that generates a full-wave rectified voltage that is a certain phase ahead of the power supply voltage. In other words, since there is no need to use a transformer, the device can be made smaller and lighter, and power consumption can also be reduced. By the way, with this configuration, the triack will not operate immediately after the AC power is turned on and until the discharge lamp starts arc discharge, the CR timer power will be low, and the pulse generation circuit may not operate sufficiently. By superimposing the rectified voltage of the lamp voltage detection circuit on the above current detection voltage via a series circuit of a diode and a resistor, a pulse is generated using the voltage across the discharge lamp that has risen almost to the power supply voltage. Even when using a discharge lamp with a small dark current in cold weather, the pulse generation circuit can be smoothly started and the discharge lamp lighting device can be started stably. After lighting, the voltage across the discharge lamp becomes lower than the lamp current detection voltage, and the lamp current detection circuit and lamp voltage detection circuit are separated by the diode in the above series circuit. do not affect each other, and the triax can be controlled by independently detecting the lamp current and lamp voltage. Furthermore, in the event of an abnormality such as a fluctuation in the lamp voltage of a discharge lamp, this fluctuation can be fed back to the pulse generation circuit via a series circuit, allowing constant power to be released even in the face of differences in lamp characteristics and fluctuations in power supply voltage. It has the effect of supplying electricity to electric lights.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing one embodiment of the present invention, Figure 2 is a circuit diagram showing an embodiment of the present invention.
The figure is an explanatory diagram of the same operation as above, and FIGS. 3 and 4 are circuit diagrams of the conventional example. 1 is a reference voltage generation circuit, 2 is a lamp voltage detection circuit, 3 is a comparison circuit, 4 is a pulse generation circuit, and 5 is a
CR timer circuit, 6 is lamp current detection circuit, 7 is series circuit (starting circuit), A is discharge lamp, S is triass, L1 is current limiting choke, L2 is auxiliary choke, E is power supply, Z6 is constant voltage circuit ( Zener diode), V1 is the reference voltage, V2 is the lamp voltage detection output, V3 is the discharge starting voltage, V4 is the pulse voltage, V5 is the voltage after rectification of the lamp voltage detection circuit,
Vc2 is the pulse current detection voltage, and Vc3 is the charging voltage of the time constant circuit.

Claims (1)

[Claims] 1. A reference voltage generation circuit that generates a full-wave rectified voltage that is a certain phase ahead of the power supply voltage by connecting a triax with an auxiliary choke in parallel and a current-limiting choke in series between the AC power supply and the discharge lamp, and A lamp voltage detection circuit that steps down, rectifies and smoothes the voltage, a comparison circuit that compares the output of the reference voltage generation circuit and the output of the lamp voltage detection circuit, and a voltage induced in the secondary winding provided in the current limiting choke. a lamp current detection circuit that obtains a lamp current detection voltage by rectification and smoothing; a series circuit consisting of a diode and a resistor that superimposes the rectified voltage of the lamp voltage detection circuit on the lamp current detection voltage of the lamp current detection circuit; A constant voltage circuit that makes the lamp current detection voltage a constant voltage, and a comparator circuit that uses the output of the constant voltage circuit as a power source, starts charging by the output of the comparison circuit, and divides the lamp current detection voltage to obtain a divided voltage. 1. A discharge lamp lighting device comprising: a CR timer that starts discharging when the CR timer reaches the discharge current; and a pulse generation circuit that generates a pulse that triggers the above-mentioned tri-attack using the discharge current of the CR timer.