JPH04109596A - Lighting device for variable-color discharge lamp - Google Patents

Abstract

PURPOSE:To make it easier for each discharge lamp to be restarted and stabilize luminescent color by setting a stopping period in which all of switching elements are turned off before a lighting period in which each switching element is turned on. CONSTITUTION:A fixed stopping period is provided in which all of switching elements S1 to S3 connected in series to respective discharge lamps L1 to L3 are turned off before each being turned on. A voltage applied to each discharge lamp L1 to L3 is higher during the stopping period than during the lighting period of each discharge lamp. Because resistances R1 to R3 each serving as a bypass circuit are connected to the respective switching elements S1 to S3, a pulse voltage at the stopping period can be stabilized by properly selecting resistance values. As a result, stable luminescent color can be obtained from each discharge lamp L1 to L3 and mixed color is also stabilized.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a variable color discharge lamp lighting device that can obtain a desired color mixture by adjusting the mixing ratio of a plurality of emitted light colors.

[Conventional technology]

2. Description of the Related Art Conventionally, a variable color discharge lamp lighting device has been provided which uses a plurality of discharge lamps that emit light of different colors and adjusts the color by adjusting the mixing ratio of each emitted color. As shown in FIG. 7, this type of variable color discharge lamp lighting device uses monochromatic discharge lamps with different emission colors (for example, primary colors of additive color mixture), and has switching elements 81 to S in ~L, respectively. and each switching element 81 to S
There is a device that sets 3 on and off (Japanese Patent Laid-Open No. 62-10
0997). Each switching element S, -S3 is controlled by the output of the lighting control circuit 3. Further, each of the discharge lamps 1 to L is lit by DC power obtained by rectifying the AC output from the inverter circuit 1 at the bridge rectifier port H@RB. The lighting control circuit 3 includes an oscillation circuit 31 that outputs a rectangular wave at a constant cycle, and uses the output of the oscillation circuit 31 to generate a monostable multivibrator 32 . is triggered. Monostable multivibrator 32. triggers the monostable multivibrator 322 when the output falls, and the monostable multivibrator 322 triggers the monostable multivibrator 32. when the output falls. trigger. In this way, as shown in FIGS. 8(a) to 8(c), pulses having an on period corresponding to the time constant set for each monostable multivibrator 321 to 323 are sequentially output. . These pulses are input to the switching elements S, ~S, respectively, and the ON period of each switching element S~S is set. Therefore, each of the discharge lamps 1 to L is lit in order. Each monostable multivibrator 32. The output of ~323 is
They are also input to the rise detection circuits 331 to 33°, respectively, so that an output that becomes “Lo” level for a short time can be obtained in response to the rise of the output of each monostable multivibrator 32 to 32. . Each rise detection circuit 33. The outputs of 333 to 333 are input to the AND circuit 34, and as shown in FIG.
, a signal with a level of ゛ is obtained. This signal triggers the timer circuit 35, and as shown in FIG. 8(e), each time the output of each monostable multivibrator 321-323 rises, a pulse having an on period tc of a certain time is output. On the other hand, a series circuit of a capacitor C, a switching element S, and a bridge rectifier circuit RB5 is connected to the output terminal of the inverter circuit 1, so that when the switching element S is turned on, the capacitor C is charged and discharged. This switching element S is controlled on and off by the above-mentioned timer circuit 35, and is controlled for each discharge lamp 1 to L,
When the switching elements 81 to S are turned on to light up the switch, the switching element S is turned on for a certain period of time tc. As a result, when the lamp voltage of discharge lamps L1-L is low, discharge from capacitor C causes discharge lamps L to L,
When the applied voltage is high, the capacitor C is charged, thereby lowering the lamp voltage. In FIG. 7, a bridge rectifier circuit RBa is inserted between the discharge lamp and the transistor Q, and both ends of the series circuit of the discharge lamp and the transistor Q are connected to the output terminal of the leakage transformer T. Further, a light receiving element of a photocoupler PC is connected between the base and the collector of the transistor Q, so that the resistance value of the transistor Q changes depending on the current flowing through the light emitting element of the photocoupler PC. That is, by changing the current input to the photocoupler PC, the current of the discharge lamp is controlled and dimmed (Japanese Patent Application Laid-open No. 51197/1982).

[Problem to be solved by the invention]

According to the configuration shown in Fig. fs7, when the switching elements S to S are turned on, the discharge lamps 1 to L are turned on. A lighting voltage is applied to each of the discharge lamps 1 to 1.
Since there is no pause period in which all discharge lamps L and L are turned off, a starting voltage higher than the lighting voltage is applied to each discharge lamp 1 to L, and restarts each discharge lamp L to summer 3. The problem is that it tends to become unstable. In particular, flickering occurs when the lamp current is reduced. Furthermore, if the configuration shown in Fig. 9 is adopted, when a high voltage is generated at the output end of the leakage transformer T, the lamp current of the discharge lamp is limited and dimmed by controlling the input current to the photocoupler PC. You can do it with multiple discharge lamps and then 1
Even if this configuration is adopted for sequentially lighting the discharge lamps 1 to 1-3, flickering will occur when each discharge lamp 1 to 1-3 is restarted when the lamp current is reduced, similar to the configuration shown in Figure 7. The problem persists. The present invention aims to solve the above-mentioned problems, and is capable of stably restarting each discharge lamp by applying a sufficient restart voltage to the discharge lamp when restarting each discharge lamp. Provided is a variable color discharge lamp lighting device capable of reducing flickering of the discharge lamp and stabilizing the emitted color by stabilizing the high voltage applied at the time of restart. This is what I am trying to do.

[Means to solve the problem]

In order to achieve the above object, the present invention uses a plurality of discharge lamps that emit light of different colors, a switching element connected in series to each discharge lamp, and a desired color mixture by controlling the ratio of the on period of each switching element. In the variable color discharge lamp lighting device, the control circuit controls to set a rest period in which all switching elements are turned off before a lighting period in which each switching element is turned on;
A bypass circuit that stabilizes the voltage applied to each series circuit of the discharge lamp and the switching element during the rest period is connected in parallel to each switching element.

[Effect]

According to the above configuration, a rest period in which all switching elements are turned off is set before a lighting period in which each switching element is turned on, so that during each rest period, the series circuit of the switching element and the discharge lamp is The applied voltage is higher than when the discharge lamp is lit, making it easier to restart the discharge lamp. Furthermore, since a bypass circuit is provided in parallel with the switching element to stabilize the restart operation, flickering of the discharge lamp is reduced and the color of the emitted light is stabilized.

Embodiment 1 As shown in FIG. 1, the output of the inverter circuit j'1llll, which provides a high frequency output, is supplied to the lighting circuit 2 to light up the discharge lamps 1 to L3. The inverter circuit 1 connects a commercial AC power supply AC to diodes D + , D 2 and capacitors Cs, C? A series circuit of a pair of switching elements S, , S5 is connected between both ends of a DC power source obtained by rectification using . The output of the inverter circuit 1 is input to the lighting circuit 2 through a DC-blocking capacitor C1 connected to the connection point of both switching elements S, , S, and a resonant circuit consisting of a capacitor C5 and a choke coil CH. The lighting circuit 2 includes three series circuits in which switching elements 81 to S are connected in series to discharge lamps L, to L, each using a monochromatic fluorescent lamp having different emission colors, and are connected in parallel to each other. It is configured to supply the output of the inverter circuit 1 to the circuit through the bridge rectifier circuit RB. In addition, each switching element 81 to S,
Resistors R1 to R1, each serving as a bypass circuit, are connected in parallel. Each discharge lamp, ~L, is set to, for example, an additive primary color (R, G, B), and the switching elements S, ~S, 3 are controlled to cycle through each discharge lamp, ~L, 1 ~L. By lighting the discharge lamps L1 to L1 and adjusting the ratio of the lighting time of each of the discharge lamps L1 to L, an arbitrary color mixture can be obtained. Here, the time for each of the discharge lamps L to L3 to light up once is set to, for example, 10111 seconds or less, and to the human eye, it appears that the discharge lamps of each color and ~L3 are emitting light at the same time. This will cause it to be recognized as a color mixture. Each of the switching elements SI to S of the inverter circuit 1 and the lighting circuit 2 is turned on and off by a control signal output from a control circuit. The control circuit includes a lighting control circuit 3 that controls the switching elements S, ~S, of the lighting circuit 2;
Switching elements S 4 , S of inverter circuit 1
and an inverter drive circuit 4 that controls s. Here, the output terminal ol~ of the lighting control circuit 3 shown in FIG. 1(b)
0. are connected to the input terminals i, to i3 of the lighting circuit 2 and the inverter circuit 1, respectively. The lighting control circuit 3 has a constant oscillation period t as shown in FIG. 2(a). A monostable multivibrator 12. which is triggered by the rising edge of the output of the oscillation circuit 11. It is equipped with Monostable multivibrator12. When triggered by the output of the oscillation circuit 11, the variable resistors VR,
and outputs a pulse having an on period t1 determined by capacitor C1. Monostable multivibrator 1
The output of No. 2 is delayed by a delay time ta through the delay circuit 13 as shown in FIG. 2(e), and then input to the differentiating circuit 14, where the falling edge is detected. That is, the differential circuit]4
The output becomes as shown in FIG.
2 is triggered. Monostable multivibrator12. outputs a pulse having an on-period t2 set by the variable resistor VR2 and the capacitor C7, as shown in FIG. 2(e). This monostable multivibrator12. The output is further passed through a delay circuit 15 and a differentiating circuit 16 to a monostable multivibrator 12. trigger. Here, the delay circuit 15
The delay time ta is set to be approximately the same as that of the delay circuit 13. Monostable multivibrator12. is shown in Figure 2 <
As shown in f), a pulse having an on period t set by the variable resistor VR and the capacitor C1 is output. Therefore, when the output of the oscillation circuit 11 rises, each of the stable multivibrators 121 to 123 is sequentially triggered. Each monostable multivibrator 121~
12. On-period of output 1. ~t3 and delay circuit 13.
15 delay time ta (t1+t2+t3+2
-ta) is the oscillation period t of the oscillation circuit 11. is set equal to or less than . Each monostable multivibrator 12. ~123 are integrated circuits commercially available for timers (for example, 1.PCl555C)
It is configured using ICI to IC3. Output and delay circuit 13 of sheep stable multivibrator 121
The output of the monostable multivibrator 121 is logically ANDed through the AND circuit 1?817, and as shown in FIG. A pulse that falls simultaneously with the falling edge is output. During the on period of this pulse, the switching element S1 is turned on. Also, the other monostable multivibrators 122, 121
During the ON period of the output of , the switching element S! , S) are turned on. In addition, monostable multivibrator 1
The output of 2l and the output of the delay circuit 13 are connected to the NOR circuit 19.
．． 192 is also input, and the NOR circuit 19. A monostable multivibrator 12. The output of is also input. Each NOR circuit 19. ．． 19. The outputs of integrated circuits IC, ~I
C, is input to the glue set terminal ■, and the monostable multivibrators 122 and 123 are prevented from operating from the rise of the output of the monostable multivibrator 121 until the fall of the output of the delay gate #r13. ,
Furthermore, the monostable multivibrator 123 is prevented from operating during the period when the output of the monostable multivibrator 122 is on, thereby reliably preventing the outputs of the output terminals 01 to 03 from turning on at the same time. ing. The inverter drive circuit 4 includes each switching element S of the inverter circuit 1. A signal is output to alternately turn on and off the pulse transformer T1. The signals are input to the switching elements S, , S5 via T2 and the like. As explained above, before the switching elements S1 to S, which are connected in series to each of the discharge lamps and to L, are turned on, there is a certain rest period in which all the switching elements 81 to S are turned off. -ing On the other hand, it is known that the voltage applied to each of the discharge lamps L1 to L is different due to the difference in resonance characteristics between when the lamp is lit and when there is no load. During the period, the voltage becomes higher than during the lighting period. That is, during the rest period, a high voltage with a pulse width of ta is applied, and the voltage necessary for restarting can be applied to each of the discharge lamps 1 to L. Furthermore, since resistors R1 to R3, which serve as bypass circuits, are connected to each of the switching elements 81 to S3, if the resistance values are appropriately selected, the pulse voltage during the rest period can be stabilized, and the lamp current can be reduced. This can prevent flickering when That is, for each switching element S, ~S, FIG. 3(a) ~(
If a control signal like e) is input, the voltage waveform between the output terminals of the bridge rectifier circuit RB will be the same as that of the resistor R6.
When ~R3 does not exist, the result will be as shown in Figure 3 IN (d), and when the resistors R1~R3 exist, the result will be as shown in Figure 3 (e).
). In this way, the waveform is stabilized and flickering is prevented. As a result, a stable luminescent color can be obtained from 1 to L of each discharge lamp, and the color of the mixed color light is also stable. In addition, if the resistance values of the resistors R4 to R1 are set appropriately, a slight discharge will occur during the rest period of each discharge lamp L, to L3, and the peak value of the pulse voltage at the time of re-ignition will be lowered. The rise of the pulse voltage becomes gradual, and the switching elements S of the inverter circuit 1...
The stress on the SS is reduced, and the life of the discharge lamp and L3 is also extended.

[Embodiment 2] In Embodiment 1, the bridge rectifier circuits R and B are connected to each discharge lamp,
In this embodiment, as shown in FIG. 4, a bridge rectifier circuit R is provided between each discharge lamp 1 to L3 and the switching element S to S3.
The configuration is such that B, ~RB, are inserted. therefore,
In the first embodiment, the discharge lamps L to L3 are lit with direct current, whereas in this embodiment, the discharge lamps L3 are lit with alternating current by the output of the inverter circuit 1. In addition, the bypass circuit is made up of resistors R1 to R3 and capacitors C to
It is a series circuit with C1ff. In this way, resistors R1 to R3 and capacitors C1, to C1
3 are connected in series to each of the switching elements 81 to S3, so when the switching elements 81 to S are turned on and off, the capacitors 011 to C are connected in parallel.
7, will repeat charging and discharging, but the resistors R1 to R3
By providing the switching elements 81 to S
, can protect the discharge of capacitors C11-CI3 from current. Furthermore, when the switching elements 81 to S3 are turned off, the voltage of the switching elements 81 to S3 rises gradually depending on the time constants of the resistors R1 to R3 and the capacitors C8 and C13, so that load fluctuations are moderated. , noise is reduced. By adopting the above configuration, the switching element Sl
Assuming that ~S:l is turned on and off by the control signals shown in Fig. 5 (6) to (e), the output waveform of the inverter circuit B1 will be as shown in Fig. 5 (6) if there is no bypass circuit. In contrast, by providing a bypass circuit, a stable waveform as shown in FIG. 5(e) can be obtained. Other configurations and operations are similar to those in the first embodiment.

[Embodiment 3] In this embodiment, a bypass circuit connected in parallel to each switching element 81 to S is connected to an inductor CH, to C
H, and capacitors CIl to CI5 are connected in series. Other configurations and operations are similar to those in the second embodiment. In each of the above embodiments, the bypass circuit is composed of a resistor, a resistor and a capacitor, and an inductor and a capacitor, respectively. , capacitor,
Other combinations of inductors or configurations using other elements may also be adopted. Furthermore, the inverter circuit 1 is not limited to the above configuration, but may include a half-bridge type, push-pull type,
- This does not preclude the use of stone-type inverters, etc. The discharge lamp ~L may be a white fluorescent lamp using a color filter, and is not limited to the three primary colors, and may be a combination of, for example, white, daylight white, and light bulb color. Furthermore, discharge lamps with different load powers may be combined.

【Effect of the invention】

As described above, in the present invention, a rest period in which all switching elements are turned off is set before a lighting period in which each switching element is turned on. The voltage applied to the circuit is higher than when the discharge lamp is lit, making it easier to restart the discharge lamp. Furthermore, since a bypass circuit is provided in parallel with the switching element to stabilize the restart operation, there is an advantage that the flicker of the discharge lamp is reduced and the emitted light color is stabilized.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention, FIGS. 2 and 3 are explanatory diagrams of the same operation as above, and FIG. 4 is a circuit diagram of a second embodiment of the present invention.
5 is an explanatory diagram of the same operation as above, FIG. 6 is a main circuit diagram showing the third embodiment of the present invention, FIG. 7 is a circuit diagram showing the conventional example, and FIG. 8 is the same as above. FIG. 9 is a main circuit diagram showing another conventional example. 1--Inverter circuit, 2--Lighting circuit, 3--Lighting control circuit, 4--Inverter drive circuit, l-1 to L
,...Discharge lamp, R2-R1...Resistor, 81-S3...
・Switching element.

Claims (1)

[Claims] (1) Variable color that includes multiple discharge lamps that emit light of different colors, switching elements connected in series to each discharge lamp, and a control circuit that controls the on-period ratio of each switching element to obtain a desired color mixture. In the discharge lamp lighting device, the control circuit controls to set a rest period in which all switching elements are turned off before a lighting period in which each switching element is turned on, and during the rest period, the connection between the discharge lamp and the switching elements is controlled. A variable color discharge lamp lighting device characterized in that a bypass circuit for stabilizing the voltage applied to each series circuit is connected in parallel to each switching element.