JPS6319972B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a constant input lighting device for a discharge lamp that is capable of suppressing the input current during the discharge lamp starting process to about the input current when the lamp is rated and stable.

Figure 1a shows a circuit diagram of a general discharge lamp lighting device for two lamps, in which main chains CH ₁ and CH _{2 are connected in series to each discharge lamp L 1 and L 2 , respectively} . . Q ₀ is a control triac, 1 is its control circuit, and both ends of the triac Q ₀ are connected to a series circuit of a capacitor C ₁ and a resistor R ₁ , and an auxiliary chain.
CH ₃ is connected in parallel. Further, a capacitor C ₀ for power factor correction is connected to both ends of the commercial power supply E. FIG. 1b shows the relationship between the lamp current I _l and the AC power supply voltage V _s of such a discharge lamp lighting device, and in the figure, T indicates that the AC control element Q ₀ is turned off from the zero cross point of the AC power supply voltage V _s . ΔT represents the off phase angle from when AC control element Q ₀ is turned off until it is turned on again. If the discharge lamps L ₁ and L ₂ connected to such a discharge lamp lighting device are discharge lamps that have high vapor pressure during lighting, such as mercury lamps, metal halide lamps, high-pressure sodium lamps, etc., immediately after starting During the transition to rated lighting, the discharge lamp L ₁ ,
The impedance of L ₂ is extremely low immediately after startup;
After that, as the vapor pressure of discharge lamps L ₁ and L ₂ increases, the discharge lamps
The impedance of L ₁ and L ₂ increases and becomes constant under the rated lighting condition. For this reason, if the inductive reactance of the main chokes CH ₁ and CH 2 that limit the lamp current I _l of the discharge lamps _{L 1} and L ₂ is constant, during the transition from the starting state to the lighting state, compared to the rated lighting state, Therefore, a large lamp current I _l flows through the main chains CH ₁ and CH ₂ . Therefore, in order to start the discharge lamps L ₁ and L ₂ with such characteristics at a constant input, in the main circuit shown in Figure 1a, immediately after starting, the off-phase angle ΔT of the triax Q ₀ is lengthened to control the lamp current. It can be seen that the off-phase angle ΔT should be shortened as _Il is narrowed down and the lighting is shifted to the rated lighting.

By the way, the fact that the conductance of the discharge lamps L ₁ and L ₂ changes during the starting process means that the phase of the lamp current I _l with respect to the power supply voltage V _s also changes, and immediately after starting, the lamp current I _l changes. Because the phase is delayed, the relationship between the on phase angle T and the off phase angle ΔT is at the position shown at point A in Figure 2,
Since the phase angle delay of the lamp current I _l decreases as it approaches the rating, the on phase angle T and off phase angle ΔT
The relationship between the two positions shifts to the position shown at point B in FIG.
Therefore, the control conditions shown in FIG. 2 are the discharge lamps L ₁ ,
This is a control condition for starting _L2 with a constant input.

By the way, as shown in Fig. 1, two discharge lamps L ₁ ,
It can be considered that the commutation phase when L ₂ is lit is approximately in the middle of the commutation phase of each of the discharge lamps L ₁ and L ₂ that are lit one by one.For example, a metal halide lamp,
When lighting a mercury lamp or the like, the discharge lamps L ₁ and L ₂ are started at the same time as the power is turned on, and both start from a state of high lamp conductance, so they can be started at a constant input under the control conditions shown in FIG.

However, when starting a high-pressure sodium lamp L _o that is started by a thermal switch 4 consisting of a heater 2 and a bimetal switch 3 as shown in Fig. 3, a sufficient kick voltage Ldi/dt is required at the time of starting.
In order to obtain this, it is necessary to secure the heater current. However, when lit together with a mercury lamp or the like, the mercury lamp starts as soon as the power is turned on, but the high-pressure sodium lamp first starts preheating the heater 2. However, since the conductance of the mercury lamp immediately after starting is sufficiently high compared to the conductance of heater 2, the commutation phase angle is delayed, and under the control conditions shown in Fig. 2, the off-phase angle ΔT of the AC control element Q ₀ is increased to reduce the heater current. High-pressure sodium lamps are difficult to start because the

Furthermore, when starting two high-pressure sodium lamps, both have low conductance during preheating of the heater 2, so there is little delay in the commutation phase, and the off-phase angle ΔT is small, ensuring a sufficient heater current. A discharge lamp that started when one of these lights started
Because the conductance of L ₁ and L ₂ becomes high, the commutation phase is delayed in accordance with the discharge lamps L ₁ and L ₂ that have started, and
As mentioned above, the heater current of the second high-pressure sodium lamp is reduced, making it difficult to start.

The present invention has been made in view of these points, and it is possible to control the high-pressure It is an object of the present invention to provide a constant input lighting device for a discharge lamp that can start a sodium lamp at a constant input.

The configuration of the present invention will be described below with reference to illustrated embodiments. First, FIG. 4 is a block diagram showing the configuration of a control circuit of a discharge lamp constant input lighting device for one lamp, which is the premise of the present invention.A power supply voltage zero-cross detection circuit 5 is connected to both ends of the commercial power supply E. The zero-cross detection circuit 5 outputs a zero-cross detection signal as shown in FIG. 5d. This zero-crossing detection signal is designed to maintain the L level from the zero-crossing point of the power supply voltage to a constant phase _T0 .
A commutation phase detection circuit 6 is installed at both ends of the triax Q ₀ .
is connected, and the commutation phase detection circuit 6 can obtain a commutation phase detection output as shown in FIG. 5c. That is, when the triax _Q0 is turned off, a voltage as shown in Fig. 5b is generated across the triax _Q0 , so
This voltage is detected and the commutation phase detection output is set to H level as shown in FIG. 5c, and the commutation phase detection output is set to L level at the zero cross point of the power supply voltage. Therefore, the output of the zero cross detection circuit 5 is the load terminal 7 of the up counter 7 _.
The up counter 7 has an initial value preset by the initial value setting circuit 8 while the zero cross detection signal is at the L level, and starts counting at phase _T0 when the zero cross detection signal rises to the H level. The up counter 7 counts the first clock _CK1 from the clock generating circuit 9a and is incremented one by one. On the other hand, the output of the commutation phase detection circuit 6 is input to the load terminal 10 ₁ of the latch circuit 10 and the load terminal 11 ₁ of the down counter 11, respectively. When the output of the commutation phase detection circuit 6 rises, the output of the up counter 7 that counts the first clock _CK1 is read into the latch circuit 10. The latch circuit 10 holds the read output until the output of the commutation phase detection circuit 6 rises in the next half cycle. The down counter 11 reads the output of the up counter 7 in the previous half cycle held by the latch circuit 10 when the output of the commutation phase detection circuit 6 is at L level. When the output of the commutation phase detection circuit 6 becomes H level, the down counter 11 uses the read value as an initial value and subtracts it one by one using the second clock _CK2 from the clock generation circuit 9b. When the output of the down counter 11 becomes zero,
Zero comparison circuit 12 detects this and trigger circuit 1
Send a signal to 3. At this time, the trigger circuit 13 generates a trigger signal for turning on the triac _Q0 .

Figure 6 shows up counter 7 and down counter 1.
In the figure, T _o-1 represents the on-phase angle in the previous half cycle, and ΔT represents the on-phase angle.
It represents the off phase angle following the on phase angle T _o in the next half cycle of T _{o -1} . That is, in the on-phase angle T _o-1 of the previous half cycle, at the phase angle T ₀ from when the zero-crossing detection pulse falls until it rises again, the initial value U ₀ is read into the up counter 7, and the zero-crossing detection pulse When the up counter 7 starts counting up, the up counter 7 starts counting up. When the triac _Q0 is turned off, the count value _Uc of the up counter 7 is held in the latch circuit 10 by the output of the commutation phase detection circuit 6. However, as described above, the output of the latch circuit 10 is input to the down counter 11 while the output of the commutation phase detection circuit 6 is at L level in the next half cycle, and the output of the commutation phase detection circuit 6 is input to the down counter 11. When it rises, the down counter 11 starts a countdown operation, and when the count value of the down counter 11 reaches zero, the triax _Q0 is turned on.
Therefore, the relationship between the on phase angle T _{o -1} and the off phase angle T _o is determined by the initial value U ₀ preset in the up counter 7 and the ratio of the periods of the first and second clocks CK ₁ and CK ₂ . It will be decided in due course. When the on-phase angle T _o-1 is large, the off-phase angle ΔT also becomes large, and conversely, when the on-phase angle T _o-1 is small, the off-phase angle ΔT also becomes small, so that the control conditions shown in Fig. 2 are finally satisfied. It is something that becomes.

However, in the discharge lamp constant input lighting device of the present invention, a single lamp lighting detection circuit 14 and the like are added to the control circuit 1 of the discharge lamp constant input lighting device for one lamp as shown in FIG. Thus, a control circuit 1 as shown in FIG. 7 is constructed. In the figure, reference numeral 15 denotes an up-down counter provided in place of the up-counter 7, which can be switched between count-up and count-down operations by a counter switching circuit 16.

The single-lamp lighting detection circuit 14 is configured, for example, by a circuit as shown in FIG.
Secondary windings are provided for CH ₁ and CH ₂ , and each
Diode bridges DB ₁ and DB ₂ are connected to the next winding. On the output side of the diode bridges DB ₁ and DB ₂ , SSS17 ₁ and 17 ₂ and transistors Tr ₁ and
Discharge lamp lighting detection circuits 18 ₁ and 18 ₂ including Tr ₂ are formed, and to explain the configuration of the diode bridge DB ₁ side, first, a resistor R ₂ is connected to the output terminal of the diode bridge DB ₁ . A series circuit of _SSS171 and a capacitor _C2 is connected to the capacitor _C2 , and the base terminal and emitter terminal of a transistor _Tr1 are connected to both ends of the capacitor C2 via a resistor _R3 . Further, the collector terminal of the transistor Tr ₁ is connected to the power supply Vcc via a resistor R ₄ . The collector terminals of the transistors Tr ₁ and Tr ₂ are connected to the input of an exclusive OR circuit 19, and the output of this exclusive OR circuit 19 is used as the output of the single lamp lighting detection circuit 14.

Next, to explain the operation of this one-lamp lighting detection circuit 14, when the discharge lamps L ₁ and L ₂ are lit,
Voltage is generated in the secondary windings of the main chains CH ₁ and CH ₂ ,
When the voltage obtained by full-wave rectification by diode bridges DB ₁ and DB ₂ exceeds the breakover voltage of SSS17 ₁ and 17 ₂ , SSS17 ₁ and 17 ₂ become conductive.
Capacitors C ₂ and C ₃ are charged and the transistor
Tr ₁ and Tr ₂ turn on. As a result, the collector terminals of transistors Tr ₁ and Tr ₂ go to L level. When the discharge lamps L ₁ and L ₂ are off, no voltage is generated in the secondary windings of the main chokes CH ₁ and CH ₂ ;
The collector terminals of the transistors Tr ₁ and Tr ₂ are at H level. In addition, when the heater current is flowing, the heater current is the discharge lamp L ₁ , L ₂
Since it is smaller than the lamp current when the lamp is lit,
When lamp current flows, _SSS171 and 172 conduct, and conversely, when heater current flows, SSS171 _{and 172} conduct.
SSS17 ₁ , 17 so that 17 ₁ , 17 ₂ are not conductive
Set the breakover voltage value of ₂ . By doing so, the transistors Tr ₁ and Tr ₂ are turned off when the discharge lamps L ₁ and L ₂ are preheated, and turned on only when the discharge lamps L ₁ and L ₂ are started. By the way, exclusive OR circuit 1
9, the output becomes H level only when the logical values of the inputs do not match, so either one of the discharge lamps L ₁ ,
When only L ₂ is lit, the output of the single lamp lighting detection circuit 14 becomes H level, and both discharge lamps are lit.
When both L ₁ and L ₂ are lit or both are being preheated, the output is at L level.

On the other hand, the counter switching circuit 16 outputs an H level at a phase angle of approximately 40 degrees from the zero-crossing point, as shown in FIG. 5e, and an L-level output at the zero-crossing point of the power supply voltage _Vs. be. The output of this counter switching circuit 16 is 1
AND circuit 2 together with the output of lamp lighting detection circuit 14
Connected to the 0 input. Therefore, when the output of the single lamp lighting detection circuit 14 is at H level, the output of the AND circuit 20 changes as shown in FIG. 5e, and when the output is at L level, the up-down counter 1 changes.
5 is added, and when the output is at H level, the up-down counter 15 is made to perform a subtraction operation. In addition, the output of the one-lamp lighting detection circuit 14 is L.
When it is at the L level, the output of the AND circuit 20 is always at the L level, and the up-down counter 15 only performs an addition operation. Therefore, two discharge lamps
When both L ₁ and L ₂ are lit, the up-down counter 15 operates as the up-counter 7, and is capable of realizing constant input control similar to the circuit shown in FIG. 4.

However, when either one of the discharge lamps L ₁ and L ₂ lights up, the one-lamp lighting detection circuit 1 is activated as described above.
Since the output of 4 becomes H level, the up-down counter 15 is switched between addition operation and subtraction operation by the output of the counter switching circuit 16, but as mentioned above, the output of the counter switching circuit 16 is changed from the zero cross point. Since it is set to reach H level at a point approximately 40 degrees away, when the on-phase angle T _o-1 is less than 40 degrees, the up-down counter 15 performs a trial operation before shifting to subtraction operation.
Since Q ₀ is turned off and the output of the commutation phase detection circuit 6 rises, the count value of the up-down counter 15 is held in the latch circuit 10, so the up-down counter 15 ends up functioning only as the up-counter 7. . On the other hand, when the ON phase angle is 40° or more, the triax Q ₀
Updown counter 15 before turning off
Since the count value shifts to the subtraction operation, the count value of the up-down counter 15 held in the latch circuit 10 when the triac _Q0 is turned off becomes smaller than when only the count-up operation is performed. Therefore, the initial value input from the latch circuit 10 to the down counter 11 after half a cycle becomes smaller as the on-phase angle T _o-1 becomes larger than 40°, and therefore the count of the down counter 11 decreases. The time it takes for the value to reach zero becomes shorter, and the off-phase angle ΔT becomes smaller. FIG. 9 illustrates the operation of the present invention as described above.
When the on-phase angle T _o-1 is less than 40°, the off-phase angle ΔT shows the same change as in the circuit shown in Fig. 4, but when only one discharge lamp L ₁ and L ₂ is lit. In this case, when the on-phase angle T _o-1 is larger than 40°, the off-phase angle ΔT is operated to become smaller as the on-phase angle T _o-1 becomes larger. Therefore, even if either one of the discharge lamps L ₁ and L ₂ is lit and the conductance becomes high, the phase of the lamp current is delayed and the on-phase angle T _o-1 is significantly delayed, the present invention does not apply. If only one light is on, the off phase angle ΔT
Since the heater current of the discharge lamps L ₁ and L ₂ that are not lit can be ensured sufficiently, even if the off-phase angle ΔT becomes small, the discharge lamps that are lit are Since there is only one lamp, there is no possibility that an extremely large lamp current will flow.

The change point between the addition and subtraction operations of the up-down counter 15 is set at a point approximately 40° away _from the zero cross point, based on the results of a computer simulation _.
is 80V/3.3A, and the auxiliary inductance CH ₃ is
66V/0.75A, which is the control condition required to ensure a minimum heater current of 0.8A when lighting two discharge lamps equivalent to 400W. The characteristics in Figure 9 are:
This control condition is satisfied, and when the horizontal axis is the on-phase angle T _o-1 and the vertical axis is the off-phase angle ΔT, there is an inflection point at the point (40°, 40°) on the coordinates. death,
When the on-phase angle T _o-1 is less than 40°, the slope of the straight line is
It is about 1.0 to 1.4.

The present invention is configured as described above, and the AC control element is turned on when only one of a pair of high-pressure sodium lamps is lit, to which heater current is supplied by closing the thermal starter at startup. When the phase angle is above a predetermined value, we installed a control circuit that controls the off-phase angle to become smaller as the on-phase angle increases, so either one of the high-pressure sodium lamps lights up and the conductance of the main circuit increases. Even if the phase of the lamp current is delayed and the on-phase angle is significantly delayed, the present invention operates to reduce the off-phase angle of the AC control element only when only one lamp is lit. Therefore, there is an advantage that sufficient heater current can be secured for the discharge lamp that is not lit, and when the on-phase angle is large, the off-phase angle becomes small by 1.
Since this is limited to the case where only the lamp is lit, it has the advantage that an extremely large lamp current will not flow even if the off-phase angle becomes small.

[Brief explanation of the drawing]

Figure 1a is a circuit diagram of a general discharge lamp lighting device.
Figure b is the same operating waveform diagram as above, Figure 2 is a diagram showing the relationship between the on phase angle and the off phase angle during constant input control,
Fig. 3 is a circuit diagram of a discharge lamp lighting device having a thermal starter, Fig. 4 is a block diagram of main parts of a discharge lamp constant input lighting device which is the premise of the present invention, and Figs. 5 a to e.
6 is an operating waveform diagram of the same as above, FIG. 7 is a block diagram of a control circuit according to an embodiment of the present invention, FIG. 8 is a circuit diagram of a single lamp lighting detection circuit of the same as above, and FIG. FIG. 3 is a diagram showing a relationship between a phase angle and an off-phase angle. 1 is a control circuit, 5 is a zero cross detection circuit, 6 is a commutation phase detection circuit, 14 is a single lamp lighting detection circuit,
CH ₁ , CH ₂ are main stations, L ₁ , L ₂ are discharge lamps, Q ₀
is an AC control element, and E is a commercial power source.

Claims (1)

[Claims] 1 A circuit consisting of a pair of parallel-connected circuits in which a high-pressure sodium lamp is supplied with heater current by closing the thermal starter in series with a current-limiting inductance at startup is connected to an AC power source via an AC control element, and the AC power source is A zero-crossing detection circuit that detects the voltage zero-crossing point, a commutation phase detection circuit that detects the off-point of the AC control element, and one that detects the state where only one of a pair of high-pressure sodium lamps is lit. A lamp lighting detection circuit is provided, and when the one lamp lighting detection circuit is in the operation of not detecting one lamp lighting, the AC control element turns off as the ON phase angle from the zero cross point of the AC power supply voltage until the AC control element turns off increases. When the on-phase angle is greater than a predetermined value during the single-lamp lighting detection operation of the single-lamp lighting detection circuit, the off-phase angle increases as the on-phase angle increases. A constant input lighting device for a discharge lamp, comprising a control circuit for controlling the angle to be small.