JPH0423399B2 - - Google Patents

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Field of Application) The present invention provides two-wire wiring for a phase control type dimmer, and cuts the filament current when the light is on at full brightness. The present invention relates to a discharge lamp lighting device that heats a filament during dimming.

(Prior Art) Conventionally, there has been known a discharge lamp lighting device that preheats the filament by flowing a filament current only during startup, and cuts the filament current after lighting to limit power consumption (for example, Japanese Patent Laid-Open No. 54-105869 ).

(Problem to be Solved by the Invention) However, when such a device is combined with a phase-controlled dimmer, when the control phase of the dimmer is increased and dimming is performed deeply, the lamp current of the discharge lamp increases. The disadvantages are that the temperature of the filament spot decreases due to a decrease in the amount of light, and that the period during which the lamp current is stopped becomes longer, causing ions to disappear and disappearing, causing flicker and other instability in lighting.

In addition, a device that performs phase control dimming and always supplies a constant filament current has been proposed (Japanese Patent Application Laid-Open No. 111997/1983).
However, since this device supplies a constant filament current when all lights are on, power loss increases due to this filament current when all lights are on, or the filament current is reduced in an attempt to reduce power loss. If it is reduced, there is a problem that the filament current at the time of dimming becomes insufficient and the life of the discharge lamp is shortened.

Furthermore, a device in which the amount of filament current is changed according to the phase control angle has also been proposed (Japanese Patent Application Laid-open No. 76796/1983). But this one is
When starting a discharge lamp, for example, if the discharge lamp is started with all lights on, the filament current will be extremely small. Therefore, there is a problem that the discharge lamp suffers from a so-called cold start, which impairs its lifespan. Furthermore, this device changes the amount of filament current as described above by providing a phase control device on the non-power side of the filament of the discharge lamp. −105869
It is clear that if an attempt is made to combine the technique with the technique disclosed in the above publication, a filament preheating means and a control means for the filament will be required, and the structure will inevitably become complicated and expensive.

The present invention was made to solve the problems in the conventional devices described above, and it cuts the filament current during full light without changing the two-wire wiring with the phase control type dimmer. In addition to reducing power loss during startup and dimming, it also prevents filament preheating or heating during startup and dimming, which reduces the lifespan of the discharge lamp and makes lighting unstable.Furthermore, it is a discharge lamp with a simple configuration and low cost. The object of the present invention is to provide a lighting device.

[Structure of the Invention] (Means for Solving the Problem) The present invention supplies power from a phase control type dimmer to an inverter device via two-wire wiring, and uses the output of the inverter device to generate a hot cathode discharge lamp. lighting and filament preheating or heating,
A filament control circuit for controlling on/off the filament current of the discharge lamp is provided, and the filament control circuit is controlled to be on by a timer circuit for a predetermined period when the discharge lamp is started, and has voltage differentiating means. The maximum value of the differential value of the input voltage to the inverter device, the lamp current, the lamp voltage, or the differential value of the envelope of the output of the inverter device, or the difference between the peak value and the average value of the differential value exceeds a predetermined value. When the dimming state is detected after the set period of the timer circuit and the dimming state is detected, the dimming state detection circuit turns on the filament control circuit and detects the dimming state. The filament current is always appropriately controlled by performing off control when no detection is being performed.

(Function) The present invention uses a timer circuit to turn on the filament control circuit for a predetermined period of time when the discharge lamp is started, so that a sufficient filament preheating current can be supplied to a hot cathode type discharge lamp. Prevent the lifespan from being shortened due to a cold start. Furthermore, when the discharge lamp is fully lit after the set period of the timer circuit, the waveform of each part does not have a steep rise due to phase control, so the dimming state detection circuit detects a differential value that is greater than a predetermined value. Since the filament control circuit is not detected, the filament control circuit is turned off. Therefore, no filament current flows through the discharge lamp,
Reduce power loss. On the other hand, if the light is in the dimming state, the dimming state detection circuit detects a differential value greater than or equal to a predetermined value based on the phase control waveform, and therefore turns on the filament control circuit. Therefore, a filament current flows through the discharge lamp, making it possible to stably light the discharge lamp even in a deep dimming state.

Moreover, since the above-mentioned filament current control can be performed using a common filament preheating or heating means and filament control circuit, the structure is simple.

(Example) Hereinafter, one example of the present invention will be described with reference to FIG. The phase control type dimmer 2 includes a triax,
It is equipped with a phase control element such as an SCR, and is capable of outputting a phase-controlled AC output from an AC power source 1 such as a commercial power source, and this itself is well known. 5 is an inverter device, which is wired with two wires to the dimmer 2;
The output from the dimmer 2 is input to light the hot cathode discharge lamp 3, and high frequency power for preheating or heating the filament is output.
These phase control type dimmer 2, inverter device 5, and hot cathode type discharge lamp 3 constitute a known discharge lamp lighting device 4.

Furthermore, in this embodiment, the high-frequency output voltage of the inverter device 5 is input, the envelope of this high-frequency output waveform is differentiated, and the maximum value of this differential value or the comparison value (difference or ratio) between the maximum value and the average value is ) exceeds a predetermined value, a dimming state detection circuit 6 that generates a dimming state detection output, and a filament control circuit that controls on/off the filament current of the lamp 3 based on the output of the dimming state detection circuit 6. 7, and a timer circuit 33 for turning on the filament control circuit 7 during a preset period when starting the discharge lamp.

Next, the inverter device 5 will be explained in detail.

Now, when the AC power source 1 is turned on, an AC output is supplied to the inverter device 5 via the dimmer 2. This inverter device 5 is, for example, a push-pull inverter circuit shown in Japanese Unexamined Patent Publication No. 56-125970, and includes a full-wave rectifier circuit 11.
A high-frequency output is generated from the non-smooth DC (rectified output) generated by the The full-wave rectifier circuit 11 generates a full-wave rectified output, which is applied via an inductor 12 to an inverter 16 having transistors 13, 14 as a switching device and an output transformer 15. As a result, in the inverter 16, the rectified output is applied as a base current to the transistors 13 and 14 via the starting resistor 17 and bias resistors 18 and 19. Then, one of the transistors 13 and 14 turns on first due to a slight imbalance, but if the transistor 13 turns on first, current flows to the primary winding 151 of the output transformer 15. Therefore, in this state 1
An oscillating voltage is generated by the inductance of the next winding 151 and the resonant capacitors 20, 21, which generates an electromotive force in the base winding 15b and turns on the transistor 14 from now on. Therefore, the transistors 13 and 14 are alternately turned on and off in the same manner to cause oscillation. Note that after the oscillation starts, the induced output of the tertiary winding 153 of the output transformer 15 is rectified and smoothed by the diode 22 and the capacitor 23, and is applied to the bias resistors 18 and 19. As a result, transistors 13 and 14 are connected to this inverter 16.
A bias current proportional to the voltage of the primary winding 151 of the output transformer 15 is supplied. Therefore, in this inverter 16, when the input voltage to the inverter 16 is high, that is, when the load power is large, the drive current is increased, and when the load power is small, the drive current is decreased, thereby achieving the optimum drive. Transistor 13,1
4 to prevent increases in switching loss and saturation loss. Furthermore, a rectified output is generated by the induced output of the primary winding 151 of the output transformer 15 via a rectifier circuit consisting of diodes 24 and 25, and this output is given to the capacitor 26 as a feedback output. Thereby, the capacitor 26 is charged in a predetermined direction. The capacitor 26 is discharged every half cycle when the rectified output of the rectifier circuit 11 becomes equal to or less than a predetermined voltage, that is, the charging voltage of the capacitor 26 in this embodiment, and provides this discharge output to the inverter 16. As a result, the output transformer 1 of the inverter 16
In the secondary winding 152 and therefore in the tertiary winding 153 of No. 5, a high frequency output without any rest period as shown in FIG. 2 1a or 1b is generated. Note that the diode 27 is configured so that the charging voltage of the capacitor 26 is the same as that of the rectifier circuit 11.
This is for isolation to disconnect the capacitor 26 from the circuit when the rectified output is lower than the rectified output.

Next, detailed operation of the dimming state detection circuit 6 will be described.
This detection circuit 6 includes an envelope detection circuit 31, a differentiation circuit 32, a timer circuit 33, and a power supply circuit 35, and operates using the voltage from the tertiary winding 153 as a power supply and an input signal. .

The power supply circuit 35 includes a resistor 36, a capacitor 37, and a zener diode 38, and generates a smoothed DC voltage obtained by stabilizing the bias voltage.

The timer circuit 33 includes a resistor 40 and a capacitor 3.
The capacitor 39 is charged by the smoothed DC voltage through a resistor 40, and the transistor 41 emits the terminal voltage of the capacitor 39.

Now, suppose that the AC power supply 1 is turned on and the inverter 16 starts oscillating. Initially, the terminal voltage of the capacitor 39, that is, the base voltage of the transistor 41 is 0, and the emitter potential of the transistor 41 is a low potential. A base current flows through the Zener diode 43, turning on the transistor 42, and thus turning on the transistor 44. This transistor 44 short-circuits the DC terminals of the full-wave rectifier circuit 45 of the filament control circuit 7,
Therefore, since the AC terminals of the rectifier circuit 45 are short-circuited, the high frequency output of the inverter circuit is supplied to the filament of the discharge lamp 3 via the filament winding 15f of the output transformer 15 and the filament transformer 46, and the filament is preheated. Ru. Then, when the filament is sufficiently preheated, the discharge lamp 3 starts discharging by the high frequency output without any rest period, which is supplied from the output transformer secondary winding 152.

After a predetermined time after the power is turned on, the capacitor 39
is charged by the smoothed DC voltage from the power supply circuit 35 via the resistor 40, turning on the transistor 41,
Collector-emitter voltage of transistor 41
Vcel is the zener voltage Vz of the zener diode 43 and the base-emitter voltage of the transistor 42
When the voltage becomes smaller than the sum of Vbe2, the transistor 42 is turned off, and therefore the transistor 44 is turned off, and the DC terminals of the rectifier circuit 45 are opened.
Therefore, after a predetermined period of time has passed after the power is turned on, the filament transformer 46 is disconnected from the filament winding 15f of the output transformer 15, the filament current of the discharge lamp 3 is cut off, and preheating is completed, and the filament power is saved thereafter. .

The envelope detection circuit 31 includes a diode 48, a resistor 49, and a capacitor 50, and is shown in FIG.
From the induced voltage of the output transformer tertiary winding 153 as shown in (at full light) or 1b (at dimming), the envelope curve as shown in FIG. 2a (at full light) or 2b (at dimming) is obtained. Generate a waveform. This envelope waveform is supplied to a differentiating circuit 32 including a capacitor 51, resistors 52 and 53, and a transistor 54. The differentiating circuit 32 differentiates the envelope waveform using a capacitor 51 and resistors 52 and 53, and generates differential waveforms as shown in FIG. 2, 3a (at full light) and 3b (at dimming). This differential waveform is, as shown in Figure 2,
When discharge lamp 3 is fully lit, the peak value is low;
Therefore, the voltage obtained by dividing this differential waveform by the resistors 52 and 53 is equal to the voltage between the base and the transistor 54.
Since it is lower than the on-voltage between emitters, transistor 5
4 remains off, and the filament current of the discharge lamp 3 remains cut off. On the other hand, during dimming, the rise of the high-frequency output voltage and hence the voltage of the tertiary winding 153 becomes steep (Fig. 2 1b), and the peak value of the differential waveform becomes high (Fig. 3b). , 53 is output from the base of the transistor 54 every 1/2 cycle of the AC power supply 1.
Transistor 54 is turned on by exceeding the emitter-to-emitter on voltage. Therefore, the capacitor 39 is 1/2
The terminal voltage is 0, same as immediately after power-on, every cycle.
Therefore, transistors 42 and 44 are turned on as described above, and discharge lamp 3 is turned on.
A filament current is supplied to. Note that the diode 55 is for rapidly discharging the capacitor 39 when the power is turned off in preparation for the next power on.

FIG. 3 shows another embodiment of the dimming state circuit 6. In FIG.
The detection circuit 6 shown in FIG. 1 is constructed of a discharge type, whereas the timer circuit of the detection circuit 6 of FIG. 1 is constructed of a charging type, which is particularly advantageous when setting a long tire time. That is, if the leakage current of the capacitor 39 increases, the timer time becomes longer in the circuit shown in FIG. only shortens the timer time.

In FIG. 3, an envelope detection circuit 31 consisting of a diode 48, a resistor 49 and a capacitor 50
and a capacitor 5 constituting the differentiating circuit 32
1. The operations of the resistors 52, 53 and the transistor 54 are the same as those in FIG. 1, but in addition to detecting the dimming state, the timing capacitor 3
It also serves as the initialization for 9. In other words, when the power is turned on, the drive voltage (output transformer tertiary winding 15
Voltage obtained by rectifying the induced voltage of 3 with diode 22)
The transistor 54 is turned on by detecting the rising edge of
Turn on the transistor 61 and turn on the capacitor 39
The power supply voltage (zener voltage Vz of diode 38)
Charge up to. After initialization when the power is turned on, the transistor 54 is turned off and the charge in the capacitor 39 is discharged through the resistor 62 in the full light state. The voltage of this capacitor 39 is emitter-followed by the transistor 41, and the voltage of the resistor 63 is the zener voltage of the zener diode 43, and the on-voltage Vbe2 between the base and emitter of the transistor 42.
The transistor 4 is larger than the sum of the base-emitter ON voltage Vbe4 of the transistor 44.
4 remains on to preheat the discharge lamp 3, and when the voltage across the resistor 63 becomes smaller than the sum voltage, the transistors 42 and 44 are turned off and the filament current of the discharge lamp 3 is cut off. During dimming, the transistors 54 and 61 are turned on by the rise of the drive voltage, and this operation is repeated every cycle of the power supply, so the voltage of the capacitor 39 is maintained at approximately the power supply voltage, and the transistor 44 is continuously turned on. Therefore, preheating is performed continuously.

FIG. 4 shows the dimming state detection circuit 6 in FIG.
Still another example will be shown. In this circuit 6, the timer utilizes the fact that the voltage of the capacitor 39 increases due to the charging current of the resistors 71 and 72, but the operation is performed using chopper control that utilizes the threshold characteristics of the gate IC to reduce the loss of the filament control transistor 44. can be kept low, and at the same time, it is possible to prevent visual flickering due to secondary side load fluctuations when the filament power is cut.

Next, the operation of the circuit 6 shown in FIG. 4 will be explained.

First, the timer elements are a capacitor 39 and a resistor 7.
1,72, and the resistance 71,7 is lower than the drive voltage.
The capacitor 39 is charged via the capacitor 2. NAND
Among the input terminals a and b2 of the gate 73, the a terminal is connected to the smoothed DC voltage VDD from the power supply circuit 35, and the b terminal is connected to the connection point between the resistors 71 and 72 via the resistor 74. A resistor 74 and a diode 75 are used to protect the gate circuit 73, a capacitor 76 is used to prevent malfunctions due to noise, and a capacitor 77 is used to lower the high frequency power supply impedance and stabilize the operation of the gate IC. When the timer is operating, the potential at the connection point of the resistors 71 and 72 is the voltage b of the gate circuit 73.
It can be considered that the voltage is input to the b terminal, and the voltage at the b terminal
Vin is the envelope voltage of the drive voltage as Vd, then Vin = Vc1 + (Vd - Vcl) x R1 / (R2 + R1) (However, Vc1 is the charging voltage of the capacitor 39 during timer operation, R1 is the resistance value of the resistor 71, R2 is the resistance value of the resistor 72), and has a DC waveform including ripples (see FIG. 5a), and both the peak value and the dip value increase with time (see FIG. 5b). Since the threshold power supply Vth of the gate circuit 73 is approximately 1/2 VDD, when Vin rises and the peak value exceeds Vth, the output of the gate circuit 73 becomes "L" during the period in which Vin exceeds Vth during the power cycle. Vin
During a period smaller than Vth, the output of the gate circuit 73 becomes "H". As Vc1 rises, Vin
The period smaller than Vth gradually becomes shorter and eventually Vin
The dip value becomes larger than Vth, and the output of the gate circuit 73 maintains the state "L". The output of gate circuit 73 drives transistors 42 and 44 via gate circuits 73B and 73C and the emitter follower of transistor 78, and the filament power is chopper controlled by switching transistor 44. Gate circuit 73B, resistor 7
9 is a loop that creates hysteresis to prevent malfunctions due to noise, and gate circuit 73C is a buffer. During dimming, as in the case of FIG. 1, the voltage of the capacitor 39 is kept close to 0 due to the transistor 54 being turned on, so the transistor 44 is continuously turned on and the filament is heated.

FIG. 6 shows still another embodiment of the dimming state detection circuit 6. In this circuit 6, the timer operating principle is the same as that in FIG. 4 (therefore, the corresponding capacitor 39 and resistors 71, 72, 74 are given the same symbols as in FIG. 4). The dimming detection section is different from that in FIG. In the figure, dimming is detected by utilizing the fact that the average value of the drive voltage during dimming is lower than when the light is full, and the maximum value of the differential value is larger than when the light is full. That is, here, the diode 48 and the capacitor 50 operate not as an envelope detection circuit but as a maximum differential value detection circuit, and the resistor 79 and the capacitor 80 operate as an average value detection circuit. At full light, the negative input of comparator 81 of the dimming detection section
The values of the resistors 82 and 83 are set so that V1 is always lower than the positive input V2 of the comparator 81, and the maximum value of V1 is greater than V2 during dimming. As a result, the output of the comparator 81 remains in the "H" state during full light, and intermittently becomes "L" in synchronization with the half cycle of the power supply during dimming, discharging the charge in the capacitor 39 of the timer circuit. It is. The comparator 84 inverts the output of the gate circuit 85 and drives the transistor 44, and the resistor 86 creates hysteresis in the threshold to prevent malfunctions due to noise.
In addition, resistors 87, 88, diodes 89, 90,
Resistors 91 and 92 and diodes 93 and 94 are used to protect the comparator, and a capacitor 95 lowers the high frequency power supply impedance to stabilize the operation of the gate IC. Resistor 36, capacitor 3
7. Zener diode 38 is for constant voltage.

In the above embodiment, the dimming state was detected from the drive voltage, that is, the tertiary winding voltage of the output transformer, but the lamp voltage, lamp current, separate winding voltage for detection, and input voltage of the discharge lamp lighting device, that is, the rectifier circuit. - The dimming state may be detected based on current or rectifier circuit output voltage/current.

In these cases as well, those skilled in the art can use the resistor voltage divider,
This can be easily accomplished by using a well-known voltage detecting means such as a detection transformer, or a well-known current detecting means such as a resistor or current transformer. However, when using a signal whose high frequency voltage level is 0 or extremely low, such as the input voltage of a discharge lamp lighting device, the envelope detection circuit can be omitted.

In addition, as shown in Figures 1, 3, and 4, there is a circuit that constantly heats the filament when the differential waveform of the envelope of the tertiary winding voltage, inverter power supply voltage, discharge lamp lighting device input voltage, etc. exceeds a certain value. The configuration is simple, and the signal processing is easy, especially when the signal is detected from the tertiary winding. In addition to voltage, inverter power supply (rectifier circuit output) voltage, discharge lamp lighting device input (dimmer output) voltage, etc., it can be detected from lamp voltage, lamp current, inverter input power supply, discharge lamp lighting device input current, etc. ,
Reliable operation is possible with many detection methods.

Further, in the above description, the filament circuit is controlled on/off using the full-wave rectifier circuit 45 and the transistor 44, but other switching elements such as an SCR may be used instead of the transistor 44, and the full-wave rectifier In place of the circuit 45, a bidirectional switching element such as a triac or a relay may be used.

[Effects of the Invention] As described above, according to the present invention, wiring is easy due to the two-wire wiring, and existing phase control type dimmers can be used without modification. Since the common filament control circuit is controlled on and off by a dimming state detection circuit having a timer circuit and voltage differentiating means, sufficient filament current can be supplied when starting the discharge lamp. Prevents discharge lamp life from deteriorating,
Furthermore, since the filament current is cut when the lamp is fully lit, power consumption can be reduced, and since the filament is heated during dimming, it is possible to prevent the discharge lamp from turning off, flickering, etc. even in a deep dimming state.

Moreover, not only the filament control circuit but also the filament preheating means can be shared.
The entire device is simple and can be provided at low cost.

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing one embodiment of the present invention, Figure 2 is a circuit diagram showing one embodiment of the present invention.
The figure shows the waveforms of various parts in the device shown in FIG. 1 at full light a and during dimming b, FIG. 3 is a circuit diagram showing another embodiment of the dimming state detection circuit in the device shown in FIG. 1, and FIG. FIG. 5 is a circuit diagram showing another embodiment of the dimming state detection circuit of FIG. 3, and FIG. 5 is a relatively enlarged or FIG. 6 is a circuit diagram showing still another embodiment of the dimming state detection circuit of FIG. 3. DESCRIPTION OF SYMBOLS 1... AC power supply, 2... Dimmer, 3... Discharge lamp, 4... Discharge lamp lighting device, 5... Inverter circuit, 6... Dimming state detection circuit, 7... Filament control circuit, 31 ...Envelope detection circuit, 32...
Differential circuit, 33...timer circuit.

Claims (1)

[Claims] 1. A phase control type dimmer capable of controlling the phase of the output voltage from an AC power source; A rectifier circuit that rectifies the output voltage of the phase control type dimmer, an output transformer, and a switching device. an inverter that converts the output of the rectifier circuit into high-frequency power and outputs the same; an inverter device that is supplied with power from the phase-controlled dimmer via two-wire wiring; A hot cathode discharge lamp that is lit and supplied with a filament current; A filament control circuit that can control on/off the filament current of this discharge lamp; A time constant circuit that includes a resistor and a capacitor; a timer means for turning on the filament current by the filament control circuit only for a preset period when starting the electric lamp; and a voltage differentiating means, which calculates the differential value of the input voltage or output voltage of the rectifier circuit, or the lamp current;
The dimming state is detected by detecting that the maximum value of the differential value of the envelope of the lamp voltage or the output of the inverter device, or the difference between the maximum value of the differential value and the average value, exceeds a predetermined value. , a dimming state circuit that controls the filament current of the discharge lamp to be turned on by the filament control circuit when the dimming state is detected after a set time of the timer means, and to turn off the filament current of the discharge lamp when the dimming state is not detected; A discharge lamp lighting device characterized by: