JPH02284383A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To adjust the output of an inverter circuit at a good precision by providing a dim signal adjusting part for adjusting a dim signal corresponding to the output of the inverter circuit. CONSTITUTION:A discharge lamp lighting device is composed of a first DC voltage element VR1 for setting a DC voltage corresponding to the maximum value of the output of an inverter circuit 1 applied to a discharge lamp l, a second DC voltage element VR2 for setting a DC voltage corresponding to the minimum value of the output of the inverter circuit 1 applied to the discharge lamp l, and a changing means Ry for changing and outputting outputs of the DC voltage elements VR1, VR2 corresponding to the duty width of a dim signal. A dim signal adjusting part 10 adjusts the dim signal corresponding to the output of the inverter circuit 1. The output adjustment of the inverter circuit can thus be performed at a good precision.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a control unit that receives a dimming signal with a variable duty from the outside, and controls the oscillation operation of an inverter circuit in accordance with the dimming signal. , relates to a discharge lamp lighting VC device for dimming and lighting a discharge lamp.

[Prior Art] As a conventional method of controlling the dimming of a discharge lamp, there is a method of performing phase control as shown in FIG. In this discharge lamp lighting device, power supplies @A and C are supplied with AC power supply AC via a power switch SW, and a dimming signal created by controlling the phase of the voltage of the AC power supply AC by a dimming control circuit 12 is transmitted. A plurality of discharge lamps 1 are connected in parallel to the dimming signal line B.

In the dimming control circuit 12, the control section 11 controls the conduction angle of the bidirectional switching element (trier gamma) Q6 to generate a dimming signal. In addition, the discharge lamp 1 has a ballast 1
It is connected to power supplies @A, C and dimming signal line B via 3. Here, this ballast 13 includes a bidirectional switching element (TRIAC) Q connected to an AC power source AC in series with the discharge lamp L, and a dimming signal sent via the dimming signal line B. An auxiliary control unit 14 that receives a signal and performs conduction control of the switching cord Q and dims the discharge lamp l; a preheating transformer T2 that preheats the filament of the discharge lamp l;
One-cage type cheek coil CH and capacitor C- are provided to supply power to discharge lamps with high efficiency.
and a coil t that periodically applies a pulse voltage to the discharge lamp l via the cheek coil CH to stably light the discharge lamp l.
, p, and a peaking circuit consisting of a capacitor Cp and a resistor Rp. In this discharge lamp lighting device, an incandescent lamp is connected between the dimming signal line B and the power supply line C, and the dimming control circuit 12 is used as a lighting circuit for the incandescent lamp.

By the way, in a discharge lamp lighting device using such a dimming control method (phase control method), the distortion of the input current is large, the harmonic component of the input increases, and the dimming signal #aB is Since the voltage is at a potential, it is easy to make incorrect connections, and the switching element Q6 of the dimming control circuit 12 needs to have a high withstand voltage, which increases the cost.

Therefore, recently, an inverter circuit 1 as shown in FIG.
is used as a ballast, and each discharge lamp l is directly connected to the power supply @A, C supplied with the AC power supply AC, and a dimming signal #[B for transmitting the dimming signal is separately provided, and this dimming signal 41B
There is one in which the control unit 4 of the inverter circuit 1 receives a dimming signal transmitted from the dimming control circuit 14 via the inverter circuit 1 and controls the dimming of each discharge lamp l.

A duty signal is generally used as a dimming signal in this discharge lamp lighting device. The reason is that when a DC voltage signal is transmitted via the dimming signal +liB, there is a risk that the signal will change due to the influence of the impedance of the transmission path. In addition, when controlling multiple lights at once,
It is necessary to isolate the alpha lamp device of each discharge lamp l, but isolation cannot be achieved with DC voltage.In this point, if it is a duty signal, the impedance of the transmission path is not a problem, and 7 Isolation can also be performed very easily using otophisolate or the like.

Here, to control the oscillation of the inverter circuit 1, a method is generally adopted in which the pulse width of a control signal that controls switching of the switching elements Q, , Q, is varied. In this method, by passing the duty signal which is the dimming signal Vd1s shown on the left side of the diagram IjIJ7 through an integrating circuit (for example, an RC integrating circuit) 15, the reference voltage V shown on the right side of the diagram
ref is created and this reference voltage V ref is shown in Fig. 8 (
The pulse of the control signal that controls the switching of the switching elements Q, Q2 according to the dimming signal is compared with the oscillation voltage such as a triangular wave according to the switching state of the switching elements Q, (or Q,) shown in a). The width is variable. The input/output voltage characteristics of the integrating circuit 15 are as follows.
As shown in the figure, the dimming signal V
The reference voltage Vref changes linearly in response to the on-duty of di.

[Problem B to be Solved by the Invention] However, in the above-mentioned system of the circuit shown in FIG. 6, there is no problem if the output of each inverter circuit 1 is constant; The output is always varied due to variations in these parts. As described above, if the outputs of these inverter circuits 1 are not the same, problems such as differences in brightness of the discharge lamps 1 will occur.

Therefore, when lighting or dimming multiple lights at once, the lp! It is necessary to make adjustments.

In this case, as shown in FIG. 10, it is conceivable to provide a volume VR for adjusting the reference voltage at the output of the integrating circuit 15, but in this case, as shown in FIG. For example, if the control signal is adjusted to a level that makes the pulse width appropriate, the levels that make the maximum and minimum pulse width of the control signal will also change accordingly, making it difficult to use a highly accurate inverter. There was a problem in that the output of the circuit 1 could not be adjusted.

The present invention has been made in view of the above point, and an object thereof is to provide a discharge lamp lighting device that can accurately adjust the output of an inverter circuit.

1. Means for Solving the Problem] In order to achieve the above object, the present invention includes a first DC voltage element that sets a DC voltage corresponding to the maximum value of the output of an inverter circuit applied to the discharge lamp, and a discharge lamp. a second DC voltage element that sets a DC voltage corresponding to the minimum value of the output of the inverter circuit applied to the lamp; and a switching means that switches and outputs the output of both DC voltage elements according to the duty width of the dimming signal. It has a sharp edge and includes a dimming signal adjustment section that adjusts the dimming signal according to the output of the inverter circuit. Incidentally, as the first and second DC voltage elements, elements whose DC voltage can be varied may be used.

[Operation 1] By configuring as described above, the present invention allows the dimming signal adjustment section to adjust the dimming signal within the range of the DC voltage set by the first DC voltage element and the second DC voltage element. The output of the inverter circuit can be continuously adjusted in a constant state according to the duty width, thereby making it possible to adjust the output of the inverter circuit with high precision.

[Embodiment 11 This discharge lamp lighting device, which shows an embodiment of the present invention in FIG. The high frequency voltage which is the output of the inverter circuit 1 is applied to the load circuit 2 including the discharge lamp I, so that the discharge lamp I is lit at high frequency. One inverter circuit is
This is an inverter with a so-called half-bridge configuration in which the switching element QI f Q 2 connected in series to both ends of the DC power supply E is turned on and off alternately by the control circuit 4 to convert the DC voltage into a high-frequency voltage. +tQ
A transistor is used as Q2, and these transistors Q,
, Q, and diodes D, , D2 are connected in antiparallel to both ends of the ends. Further, in this inverter circuit 1, the control circuit 4 controls only the switching of the transistor Q2, and the switching of the transistor Q1 is performed using a base transformer T connected in series to the load circuit 2. . Furthermore, this inverter circuit 1
The activation of the
This is done by supplying the base current of the transistor Q2 with the starting circuit 3 consisting of the transistor Q2. The load circuit 2 is composed of a chiller coil L3, a capacitor C3, a discharge lamp 11, and capacitors C2, C, which constitute a series resonant circuit together with the choke coil L1, and a switching element Q.
2, a choke coil L3, a capacitor C1, and a parallel circuit of the discharge lamp l and the capacitor C2 are connected in series, and a capacitor C is connected to the non-power supply side of the filament of the discharge lamp l.
1 are connected in parallel. Note that the above capacitor C3 is a DC cut capacitor, and the switching element Q
It also has the function of supplying the charge charged when the switching element Q2 is turned on as a power source when the switching element Q2 is turned on. Also, capacitor C
1 also functions as a preheating capacitor. The control circuit 4 that controls the operation of the inverter circuit 1 is an IC (for example, MN4538
(MEC, etc.) 5. It is composed of a transistor Q, a high-quality capacitor C1, and resistors R1 to R1. When the voltage across the transistor Q2 detects a fall, the transistor Q2 is turned on for a certain period of time from the time of this fall. The state is held and the transistor Q2 is turned off after this period has elapsed.

The operation of the basic configuration of the discharge lamp lighting device will be briefly described. Now, when the DC power supply E is supplied, the capacitor C5 is charged by the DC power supply E through the resistor R4, and when the charge in the capacitor C1 reaches the breakover voltage of the diac Q, the diac Q5 becomes conductive. The base current is supplied to the transistor Q2, and the transistor Q
2 turns on.

Here, when the transistor Q2 is turned on, the voltage divided by the resistors R, , R, connected to both ends of the transistor Q2 decreases, so that a voltage is applied to IC5 and a voltage is applied to the Iyg11 child B. When IC5 is activated in this way, capacitor C4 is charged via resistor R5. That is, the on period of the transistor Q2 is determined by the time constant of the resistor R1 and the capacitor C1 at this time. During the charging period of the capacitor C4, the output Q of the IC5 goes high and the output ◇ goes low, so that the transistor Q is turned on and the transistor Q is turned off.

Therefore, after the transistor Q2 is activated by the activation circuit 10, the ON state of the transistor Q2 is maintained by supplying the base current through the transistor Q. Then, the charging voltage of capacitor C1 reaches a predetermined voltage (
When the on period of transistor Q2 elapses, the output Q of IC5 becomes low level and the output becomes high level, so transistor Q3 turns off and transistor Q
, turns on. Therefore, the base current of transistor Q2 is bypassed by transistor Q4, and transistor Q2 is controlled to be turned off.

When the transistor Q2 is turned on in this manner, a voltage is induced in the secondary winding of the base transformer T1 in a direction that biases the transistor Q1, so that the transistor Q is turned on. At this time, capacitor C for DC cut
A current flows through the transistor Q1 using the charge charged to 1 as a power source. Note that during the on period of the transistor Q2, a voltage that reverse biases the transistor Q is induced in the secondary winding of the base transformer T1, and the transistor Q1 is held in the off state. And the transistor Q1
is turned on and reaches saturation, the base transformer T1
, a voltage that applies a reverse bias to transistor Q is induced in the secondary winding, turning off transistor Q1.

When transistor Q is turned off in this way,
Current flows through the primary winding of the base transformer T to keep the transistor Q in the off state, turning on the diode D2, which causes the voltage across the transistor Q2 to fall and triggering the IC11 in the control circuit 4. ff terminal B
A bird is charged in the same way as described above. Therefore, from then on, the operations described above are repeated, and the inverter circuit 1 continues the oscillation operation.

Hereinafter, the dimming signal adjustment section 10 and the dimming control section 9, which are the features of this embodiment, will be explained. The dimming signal adjustment section 10 includes:
Volume V as a DC voltage element that outputs a voltage that determines the maximum value of on-duty of switching element Q2
R, and a volume VR2 as a DC voltage element that outputs a voltage that determines the minimum value of the on-duty of the switching element Q. The volume VR2 is driven in accordance with a duty signal that is a dimming signal, and is driven to the duty signal by switching the contact. and a relay R serving as a switching means for switching and outputting the voltage signals set by the respective volumes VR, , VR, in accordance with the above. A reference voltage generation circuit 6 consists of a resistor R6 and a capacitor C, which create a reference voltage which is a DC voltage by multiplying the switching output ■., a diode D3% which creates a triangular wave from the output Q of IC5, a capacitor C2 and It consists of a triangular wave generating circuit 7 consisting of a resistor R2, and a comparing circuit 8 which compares the output of the triangular wave generating circuit 7 with the output of the reference voltage generating circuit 6 and outputs the comparison output to the reset input CD of the IC5. Yes.Relay Ry is a photocoupler PC
The fin rate of the discharge lamp lighting device is maintained in such a way that the discharge lamp lighting device is driven by the same amount as the other discharge lamp lighting devices.

The dimming signal adjustment unit 10 of this embodiment includes a volume VR that outputs a voltage that determines the maximum value of the on-duty of the switching element Q2, and a volume VR2 that outputs a voltage that determines the minimum value of the on-duty of the switching element Q2. Since the respective outputs of the relays R and R are alternately output by switching the contact R of the relay R, which is driven according to the duty signal, a linear control signal corresponding to the duty signal is generated in the maximum and minimum on-duty ranges. is obtained. In other words, by changing the duty signal from 0% to 100%, the output of the discharge lamp 1 can be continuously changed from the maximum value set by the volume VR, to the minimum value set by the volume R2. . Output V of the dimming signal adjustment section 10. For example, as shown in FIG. 2, six points are adjusted with the volume VR, and a point a is adjusted with the volume VR2. In this way, the desired maximum and minimum on-duty of the switching element Q2 can be independently determined, and the on-duty of the control signal can be continuously varied in a constant state within the above-mentioned on-duty range. When trying to obtain the desired value, other on-duty values do not change, and therefore, the dimming signal can be adjusted with high accuracy.

The output v0 from this dimming signal adjustment W110 is sent to the dimming control section 9, and the dimming control of the inverter circuit 1 is performed as follows. That is, the output v0 of the dimming signal adjustment section 10 is integrated by the reference voltage generation circuit 6 to create the reference voltage Vref.
At the same time, from the output 6 of the IC 5, a triangular wave generating circuit 7 generates a triangular wave output (2) according to a control signal for turning off the switching element Q2, and these outputs Vref and V are compared in a comparing circuit 8. Now, as shown in Fig. 3, when the triangular wave output ■1 exceeds the reference voltage V ref, the output of the comparator circuit 8 falls to a low level, so a reset signal is input to the reset input CD of IC5. At this time, regardless of the rise of the voltage across transistor Q2, transistor Q is forcibly turned on, and transistor Q2 is forcibly turned on. Therefore, the on-period of the transistor Q is forcibly controlled to be short, so the output of the inverter circuit 1 is kept small (suppressed), and the discharge lamp 1 is dimmed and lit.

[Embodiment 2] FIG. 4 shows another embodiment of the present invention. In this example, the duty signal is switched only between 0% and 100%, that is, the circuit is designed to switch only between full lighting and a constant dimming state. Since the reference voltage obtained is a binary DC voltage of high and low values, a switching means and a reference voltage generating circuit are not required. Therefore, it is sufficient to connect a phototransistor of a 7t tocoupler PC in parallel in series between the output of the volume VR2 and the ground.The operation of this embodiment is such that when the output of the lighting control device is 0% of the duty signal, the 7t totrannostar is connected in parallel. When the duty signal is off, the output is maximum, and when the duty signal is 100%, the transistor 7 is turned on and the output is minimum. Note that the resistor Ry connected to the output of the volume VR, VR2 =
The value of R@ is sufficiently larger than the resistance value of the volumes VR, , VR2 (R, .

Rs>>VR+tVRz).

[Effect of the Invention 1 As described above, the present invention provides a first method for setting a DC voltage corresponding to the maximum value of the output of the inverter circuit applied to the discharge lamp.
a second DC voltage element that sets a DC voltage corresponding to the minimum value of the output of the inverter circuit applied to the discharge lamp, and a second DC voltage element that sets the output of both DC voltage elements to the duty width of the dimming signal. and a switching means for switching output according to the output of the inverter circuit, and a dimming signal adjustment section that adjusts the dimming signal according to the output of the inverter circuit.
The output of the inverter circuit can be continuously adjusted in a constant state according to the duty width of the dimming signal within the range of the DC voltage set by the DC voltage element and the second DC voltage element. Therefore, when trying to obtain the on-duty of the control signal in a certain desired region as in the past, the on-duty of the control signal in other regions does not fluctuate, and the output of the inverter circuit can be adjusted with high precision.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of one embodiment of the present invention, Fig. 2 is an output waveform diagram of the dimming signal adjustment section same as above, Fig. 3 is an operation explanatory diagram of the dimming control section, and Fig. 94 is another embodiment. 5 is a circuit diagram of a conventional example, FIG. 6 is a circuit diagram of another conventional example, FIGS. 7 and 8 are explanatory diagrams of the same dimming signal control section, and FIG. A characteristic diagram of the input/output voltage of the optical signal control section, FIG. 10 is an explanatory diagram of an improved example of the same, and FIG. 11 is an explanatory diagram of the operation of the same. 1 is an inverter circuit, 4 is a control unit, 10 is a dimming signal adjustment unit, Q,, Q2 is a switching element, l is a discharge lamp,
VR+tVRzliK+) Knee A, Ry beam L/-
is a contact, and E is a DC power supply. Agent Patent Attorney Ishi 1) Ai Seven 1... Inverter circuit Figure 4 Figure 2 Figure 3 - Figure 5 Figure 6 Δ Figure 7 Figure 8 Figure 9 Figure 10 Figure 11

Claims (2)

[Claims] (1) The control section converts the DC voltage into a high frequency voltage by switching the switching element, applies this high frequency voltage to the discharge lamp to light the discharge lamp at high frequency, and sends a dimming signal with variable duty to the control section. In a discharge lamp lighting device that dims and lights a discharge lamp by controlling the oscillation operation of the inverter circuit according to the dimming signal received from the outside, the maximum value of the output of the inverter circuit applied to the discharge lamp is a first DC voltage element that sets a corresponding DC voltage; a second DC voltage element that sets a DC voltage that corresponds to the minimum value of the output of the inverter circuit applied to the discharge lamp; A discharge lamp lighting device comprising a switching means for switching an output according to a duty width of a dimming signal, and a dimming signal adjustment section adjusting a dimming signal according to an output of an inverter circuit. (2) The discharge lamp lighting device according to claim 1, wherein the first and second DC voltage elements are capable of varying DC voltage.