JPH04163886A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To protect a discharge lamp and its device without extinguishing the lamp completely by furnishing a means which transfers to the operation with the output characteristic for rated lighting after a certain specified period which is longer than the period in which a normal discharge lamp started attains the rated state approximately. CONSTITUTION:If a lamp la is normal, its voltage Vla rises and lights up stably at Point B in the attached illustration-in the case of slow leak, the voltage Vla can not rise fully but helds itself at Point C. After a certain period of time, a timer circuit 2 gives a clock output VT at H level, and then the output level of an OR circuit OR1 is H, that of a reversing circuit G1 is L, and that of an AND circuit AND2 is L, while another AND circuit AND1 admits passage of frequency f1 Therefore, MOS transistors Q1, Q2 are switched with frequency f1, and the lighting device transfers to the rated operation when the lamp la will continue lighting at Point D with a minor lamp amperage Ila, and component endurance amount for inductor, etc., may be small. Thus the lamp and its device are protected, and they can be constructed in a small size and at low cost, and if it applies to the head light of a car, the car can manage to run during nighttime to a certain degree of performance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a discharge lamp lighting device suitable for lighting a high-intensity discharge lamp (HID lamp).

[Prior Art] Generally, in an HID lamp, the pressure inside the discharge tube is low immediately after the start of discharge, and the vapor pressure of the metal that emits light due to the discharge energy is low, so the luminous flux is small. As the discharge tube temperature increases, the metal vapor pressure increases and the luminous flux also increases and eventually stabilizes. At this time, it can be considered that the metal vapor pressure is proportional to the lamp voltage.

FIG. 12 shows a conventional example of a lighting device for an HID lamp. The AC power source AC is connected to F (
ID lamp la is connected. The load characteristics of this lighting device are shown in Fig. 13. At point A immediately after 0 lighting, the lamp voltage Vfa is low, and at point B, where the light output is stable, the lamp voltage Vfa is
1a becomes higher. The operating point gradually moves from point A to point B.

For this reason, it takes time for the HID lamp to stabilize its luminous flux (light output).

Therefore, when transitioning from point A to point B in Fig. 13, the output of the lighting device is increased and an excessive current 11a is passed through the HID lamp 1a, thereby rapidly increasing the temperature of the arc tube and stabilizing the luminous flux. There is a circuit method that shortens the time it takes.

FIG. 14 shows an example of the circuit. In the figure, L is an inductor,
LT beam is a cage transformer, Ry is a relay, and S is its contact.

When the lamp voltage VNa reaches the sensitive voltage of the relay Ry,
Switch the contact S from the a side to the b side. The output characteristics of this lighting device are shown in FIG.

By the way, in HID lamps, the pressure inside the arc tube may not rise sufficiently due to the escape of metal vapor within the arc tube. This is called slow leak. In this case, the lamp voltage V1a remains low and sufficient light output cannot be obtained. When a slow leaking HID lamp is lit with the lighting device shown in FIG. 14, the lamp continues to operate at point 0, which is in the middle of the transition from point A to point B in FIG. 15.

If it is a normal lamp, the transition from point A to point B is quick, so the winding wire of the coil or the like used in the lighting device may have the same wire diameter as the conventional example shown in FIG. However, in the case of a slow leak HID lamp, excessive current continues to flow, so the wire diameter is required to be thicker than that capable of withstanding the current. Therefore, due to the increase in temperature of the winding, the lighting device becomes large and heavy. If the wire diameter is not increased, there is a risk of ignition if heat generation is significant. Additionally, the lamp may be damaged.

Therefore, as a protection measure for the lighting device against slow clamps, a thermal protector TP is attached to the winding of the ballast as shown in Figure 16, and in the event of an abnormal temperature rise due to slow leakage, etc. It has been proposed to cut the
However, in this case, the lamp 1a completely stops discharging. For this reason, for example, if HID lamps are used in vehicle headlights, it becomes impossible to drive at night and cannot be used in emergencies. there were.

[Problem to be solved by the invention] The present invention has been made in view of the above points,
The purpose of this is to use a discharge lamp lighting device that allows excessive lamp current to flow from immediately after startup until stabilization in order to shorten the luminous flux stabilization time, and when a slow leak HID lamp is lit, To protect a lighting device without completely extinguishing a lamp or increasing the size of the lighting device.

[Means for Solving the Problems] In order to solve the above problems, in the discharge lamp lighting device of the present invention, as shown in FIG. and a second output characteristic for supplying an excess lamp current INa than usual during a period when the lamp voltage V1a is lower than the rated value immediately after starting the discharge lamp.
A normal discharge lamp in a lighting device with output characteristics of ! It is characterized by providing an output characteristic switching means that shifts to the operation of the first output characteristic for rated lighting after the elapse of a predetermined time τS that is longer than the time required for a to reach approximately the rated state from the start. That is.

[Function] In this way, in the present invention, after the predetermined time τS, which is longer than the time required for a normal discharge lamp la to reach approximately the rated state after starting, has elapsed, the first Since the operation is shifted to the output characteristic, the lamp voltage Vl
Regardless of a, after the predetermined time τS has elapsed, the lamp stops operating with the second output characteristic that supplies an excessive amount of lamp current 1a, so the lighting device can be reliably protected.

U Example 1] FIG. 1 is a circuit diagram of a first embodiment of the present invention.

The circuit configuration will be explained below. The DC power supply ■8 is connected to a MOS transistor Q via a power switch SW.
, Q2 are connected in series.

MOS) transistors Q, Q2 have diodes DI.

D2 are connected in antiparallel. A series circuit of a DC component cutting capacitor C1, a resonance inductor L, and a capacitor C2 is connected to both ends of the MOS transistor Q2. A lamp /a is connected in parallel to both ends of the capacitor C2. Also, lamp 1a
The voltage Vna across is rectified by the diode D3,
The voltage is divided by the resistors R, , R2, smoothed by the capacitor C1, and detected as the output voltage Va of the V/a detection circuit 1. This voltage Va is compared with the reference voltage Vr by a comparator CMP, and the comparison output ■L is an OR circuit ○R1
is supplied to one input of the The output VT of the timer circuit 2 is input to the other input of the OR circuit ORI. The output of the OR circuit ORI is used as one input of the AND circuit ANDI, and is also inverted by the inverting circuit G1 and used as the other input of the AND circuit AND2. AND circuit AND 1.

The output frequencies f, , f2 of the first and second oscillators are supplied to the other input of AND2. AND circuit AN
D1. The output of AND2 is input to an OR circuit OR2. The output of the OR circuit OR2 is divided by the frequency divider DTV and passed through the drivers DR, DR2 (MOS).
It is input to the gates of transistors Q, , Q2.

FIG. 2 shows the output characteristics at operating frequencies f, f2 of this embodiment. In the figure, ■ indicates the operation of the slow clamp, and ■ indicates the operation of the normal lamp. Further, FIG. 3 is an operational waveform diagram of this embodiment. In the figure, the left half shows the operating waveform of a normal lamp, and the right half shows the operating waveform of a slow clamp.

Hereinafter, the output voltage Va of the 6Vψa checking ratio circuit 1 and the reference voltage Vr will be compared to explain the operation of this embodiment.
If a > V r, the comparison output VL is "High" level, and if Va≦Vr, the comparison output VL is "'Low"
level. In the timer circuit 2, after the power switch SW is turned on, the time measurement output ■T is at the 'Low' level for a certain period of time τS, and thereafter the time measurement output vT is at the 'High' level.

The frequencies f, f2 of the drive signal source of the inverter device are both rectangular waves with a duty of approximately 50%, and the frequency f1 during rated operation and the frequency f2 during excessive operation immediately after startup are as follows:
With respect to the resonant frequency f0 of the capacitor C2 and the inductor, there is a relationship of f o < f 2 < f +.

This signal is divided by the frequency divider DIV and turns on/off the MOS transistors Q, Q2 alternately, so that a resonant current flows through the resonant circuit of the capacitor C2 and the inductor L1, and the current flows across the capacitor C2. The resulting resonant voltage drives the discharge lamp &a.

First, when the power switch SW is turned on, the inverter device starts operating, the lamp 1a lights up, and the lamp voltage V1
a becomes low, Va<Vr, and the comparison output ■[ of the comparator CMP becomes the "LoIl" level. The timer circuit 2 starts timing at the same time as the power switch SW is turned on, and the timing output V is “L” for a predetermined time τS.
At this time, since the inputs vL and vT of the OR circuit ORI are both at the 'Low' level, the output of the AND circuit AND1 becomes the 'Lou+°' level. Also, the output of the inverting circuit G1 becomes High. ” level, the AND circuit AND2 passes the frequency f2. Therefore-
MO8) The transistors Q, , Q2 are switched by the frequency f2 and the output of the lighting device becomes excessive. Therefore, the temperature of the lamp 1a rises rapidly, and the lamp voltage Via
rises quickly.

When the lamp is normal, the lamp voltage V1a increases and V
When a > V r, the comparison output VL of the comparator CMP becomes 'High' level. Therefore, the OR circuit O
The output of R1 is "High" level, and the output of inverting circuit G is "Low" level. Therefore, the AND circuit AN
The output of D2 becomes "'Low" level, and AND circuit A
NDI passes through frequency f. Therefore, the MOS transistors Q, Q2 are switched at the frequency f, and the lighting device operates at its rated value.The normal lamp 1a lights stably at point B in FIG.

On the other hand, in the case of slow clamp, the lamp voltage VNa
cannot rise completely and maintains the 0 point in Figure 4.

In this case, after the timer circuit 2 completes timing the predetermined time T5 and the 7 clock outputs reach the "High" level, the output of the OR circuit OR,1 goes to the "High" level.
The output of the inverting circuit G is at the °'Log' level, the output of the AND circuit AND2 is at the 'Lou+' level, and the AND circuit AND1 passes the frequency f1.
Since the S transistors Q, , Q2 are switched at the frequency f, the lighting device shifts to its rated operation. Thereafter, the lamp la continues to be lit at point D in FIG. However, since the lamp current ■ea is small, it does not adversely affect the withstand capacity of the lighting device. In this way, since excess current is not maintained continuously, the withstand capacity of the inductor and other components can be reduced and the inductor can be made smaller, lighter, and lower in cost. Further, since the lamp la is not completely turned off, it can be used only in an emergency. General lighting has the advantage of not causing darkness, and vehicle headlights allow you to drive at night.

[Example 2] FIG. 4 is a circuit diagram of a second embodiment of the present invention.

In this embodiment, leakage transformer T1 and inductor L
! A steel type ballast is used in combination. If the lamp voltage Vt'a is low, the relay Ry1 will not be deceived, so its contact S1 is on the a-pole side.

Therefore, input power ■. is not boosted by the leakage transformer T, but only the inductor L1 is used as a stabilizing element without passing through the leakage transformer T or the cage inductance component.

After that, when the lamp voltage Vla increases, the relay RY
Since t is sensitive, the contact S1 switches to the b pole side.

Therefore, input power ■. The voltage is boosted by a cage transformer T, and the stabilizing element is an inductor, and a cage transformer T is used as a stabilizing element.
It is the sum of the leakage inductance components of 1. At this time, if proper design is done, such as by setting the value of inductor L1 sufficiently small, the lighting device will have a higher secondary short circuit current when contact S1 is on the a-pole side than when it is on the b-pole side. can be configured. This makes it possible to speed up the rise of the luminous flux immediately after starting.

FIG. 4 shows the operation of relay RY2 and its contact S2. After the power switch SW is turned on, the AC power source (I) is rectified by a diode D, current-limited by a resistor R1, smoothed by a capacitor C4, and the resulting voltage Vc is applied to a relay Ry2. Voltage Vc of capacitor C1 increases, and when it eventually reaches the sensitive voltage of relay RV2, relay Ry2 operates and contact S2 opens.

FIG. 5 shows the output characteristics of this embodiment. If the lamp is normal, it will operate at point A immediately after lighting, and the lamp voltage will be V1.
a rises, the relay R'l + is sensitive, the contact S1 switches from the a pole side to the negative pole side, and the rated output lighting state is reached at 8 points. A slow clamp operates at point A immediately after lighting, but after that, the lamp voltage Vβa cannot rise completely,
Relay Ry1 remains unresponsive and maintains zero point operation. In this case, after the predetermined time τS has elapsed, relay Ry2
By opening the contact S2, an inductor L2 is added as a stabilizing element, and the light is maintained at point D in FIG.

As a result, the transition from point 0 on the characteristics of ■ in Figure 5 to point D on the characteristics of ■, where the lamp current 11a is even lower, is safer than the transition from point C on the characteristics of ■. This is a great protection measure. Note that in the case of a normal lamp, even if the contact S2 is turned off, since the contact S1 is on the b pole side, there is no effect at all.

[Example 3] FIG. 6 is a circuit diagram of a third embodiment of the present invention.

The circuit configuration will be explained below. A smoothing capacitor C3 is connected to the DC power source Vo via a MOS transistor Q0 and an inductor L1.

In the series circuit of the inductor L and capacitor C3, there is a diode D for flowing regenerative current. is connected. This constitutes a step-down chopper circuit. Capacitor C! The voltage obtained is divided by resistors R1 and R2, smoothed by capacitor C1, voltage regulated by Zener diode ZD as necessary, and then sent to comparator CMP.
The reference voltage ■L is applied to the inverting input terminal of the inverter. A high frequency sawtooth wave signal fHF is input from a sawtooth wave oscillator to a non-inverting input terminal of the comparator CMP.

The output of comparator CMP is connected to M via driver DR.
OS) transistor Q. Supplied between the gate and source of.

The DC voltage obtained across capacitor CI is applied to inductor L2.
The voltage is applied to a full bridge circuit consisting of transistors Q and Q4 (MOS) through a series circuit of impedance IL and impedance IL. However, a normally closed thermal protector TP is connected in parallel to the impedance IL, and this thermal protector TP is thermally coupled to the inductor L2. The full-bridge circuit MOS) transistors Q, ~Q4 output drivers DR, ~DR by the output obtained by dividing the low frequency signal fLF output from the low frequency signal source by a frequency divider DIV.

The connection point between the IMOS transistors Q, , Q3 which are turned on and off via the MOS transistors Q2, . Q
A lamp 1a is connected between the 4 connection points.

FIG. 8(a) shows the low frequency operation of this embodiment, in which transistors Q, Q
, is on, MOS transistor Q2. Q3 turns off, and in the second half, MOS) - transistor Q2゜Q3 turns on,
MOS) transistors Q, , Q, are turned off. As a result, the period TL determined by the low frequency signal fLF (=1/kF)
A rectangular wave voltage of is applied to the lamp 1a, and the lamp 1a is lit with a low frequency rectangular wave.

FIGS. 8(b) and 8(c) show the high frequency operation of this embodiment. Chopper circuit MOS) transistor Q
. is PWM controlled by the voltage Vc of capacitor C8. The reference voltage VL increases or decreases in accordance with the voltage Vc of the capacitor C1, and the high frequency signal fHF of the sawtooth wave oscillator and the reference voltage ■L are compared by the voltage comparator CMP, and the comparison output is used to control the MOS transistor Q. or on/off controlled. When Vc of capacitor C1 is low, lamp voltage V
Since la is low and voltage VL is also low, comparator CMP
However, the width of the output pulse is wide. When the voltage Ve of the capacitor C1 rises, the lamp voltage V1a rises and the voltage ■L also rises, so that the width of the pulse output from the comparator CMP becomes narrower. When the voltage Vc further increases,
Since the voltage VL is limited by the Zener diode ZD and has a constant value, when the lamp voltage Vla is equal to or higher than a predetermined value, the MOS) transistor Q has a constant pulse width. is switched. As a result, the output characteristics shown in FIG. 9 are obtained.

For example, in this embodiment, the lamp voltage V1a is low at the time of starting, and A
If the slow clamp operates at point 0 and then continues to maintain operation at point 0, excessive current will flow and the inductor L
As the temperature rise of 2 becomes large, the thermal protector TP thermally coupled to the inductor L2 is opened after a certain period of time, and an impedance IL is inserted in series with the inductor L2, so a voltage drop Vx occurs at this impedance IL.

Therefore, the voltage Vc of capacitor C1 is V la + V
x, and the operating point shifts to point D in FIG. 9, isometrically shifting to the operating point on the higher side of the lamp voltage Via, so the circuit current can be reduced. In addition, in this example,
By using an incandescent lamp as the impedance IL, a certain degree of luminous flux compensation becomes possible, and safety is further improved.

[Example 4] FIG. 10 is a circuit diagram of a fourth embodiment of the present invention.

In this embodiment, a thermal protector TP is added to the embodiment shown in FIG. 1, and an inverting circuit G2 operated by the output of the X point, and an AND circuit AND3 . AND4,
An OR circuit OR3 and a third signal source (frequency L) are added. The basic operation of the comparator CMP and the timer circuit 2 is the same as the embodiment shown in FIG.

FIG. 11 is an explanatory diagram of the operation of this embodiment. If the slow clamp continues to light up at point D, the lamp current 11a at this time is higher than at point B at the rated output, so the heat generation in inductor L1 will also increase, and the stress on other parts will also increase. . Therefore, it is desirable to have a design that can withstand this, but for example, there are demands such as a desire to make the device a little more compact, or a desire to thermally protect the components when the ambient temperature is abnormally high.

In view of these points, in this embodiment, a thermal protector TP that is thermally coupled to the inductor L is added, and when the heat generation of the inductor L becomes large, the thermal protector TP is opened, and the output of the inverting circuit G2 is is set to a "Low" level, the output of the AND circuit AND3 is set to a "Low" level, and a signal of frequency f is sent from the third signal source from the AND circuit AND4 to the OR circuit OR3 to the frequency divider DI.
Supply to V.

At frequency f3 from the third signal source, the output is even lower than when operating at frequency f1, and it operates at point E. Thereby, the lighting device can be further safely protected.

[Effects of the Invention] As described above, in the present invention, the first output characteristic for lighting a high-intensity discharge lamp at the rated value and the lamp voltage immediately after starting the discharge lamp with respect to the rated lamp voltage are provided. and a second output characteristic for supplying an excess lamp current compared to normal while the lamp current is low. Since the device is equipped with a means for switching the output characteristic to switch to the operation of the first pressure characteristic for rated lighting after the elapse of time, even if a discharge lamp such as a slow clamp lamp with an abnormally low lamp voltage is turned on, Since excessive current does not continue to flow, it is possible to prevent damage to the discharge lamp, reduce the thermal withstand capacity of the lighting device, and protect the lighting device. Unfortunately, although it does not completely turn off the discharge lamp, it does not completely eliminate its function as a lighting device, and it has the advantage that it can be used in an emergency.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of the first embodiment of the present invention, FIG.
4 is a circuit diagram of the second embodiment of the present invention; FIGS. 5 and 6 are diagrams of the same operation; FIG. 7 is a circuit diagram of the third embodiment of the present invention. 8 and 9 are explanatory diagrams of the same operation as above, FIG. 10 is a circuit diagram of the fourth embodiment of the present invention, FIG. 11 is an explanatory diagram of the same operation as above, and FIG. 12 is a circuit diagram of the conventional example. , FIG. 13 is an explanatory diagram of the same operation as above, FIG. 14 is a circuit diagram of another conventional example, FIG. 15 is an explanatory diagram of the same as above, and FIG.
The figure is a circuit diagram of yet another conventional example. 1 is a via detection circuit, 2 is a timer circuit, CMP is a comparator, and 1a is a lamp.

Claims (1)

[Claims] (1) A first output characteristic for lighting a high-intensity discharge lamp at the rated value, and a first output characteristic for supplying an excess lamp current compared to normal during a period when the lamp voltage is lower than the rated value immediately after starting the discharge lamp. In the lighting device having the second output characteristic, after a predetermined time period that is longer than the time required for a normal discharge lamp to reach approximately the rated state after starting, the first output characteristic is activated for rated lighting. A discharge lamp lighting device characterized by being provided with switching means for changing output characteristics.