JP2002136151A - Power supply and discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply and a discharge lamp lighting device wherein a voltage required for the stable operation of a control circuit is ensured, even when power is applied or the supply voltage is low. SOLUTION: A variable resistor portion 8 is used for a resistor for passing base current, through the transistor Q6 for control of a control source circuit 6, and the control circuit 7 is provided with a control function of varying the resistance value of the variable resistor portion 8 and controlling the value to a prescribed resistance value lower than a resistance value, in steady state for a certain period of time after a power switch 2 has been turned on. The control function is implemented by a comparator CMP3 whose noninverting input terminal is connected with a direct-current power supply 1 via the power switch 2 and which produces output; when the voltage inputted to the noninverting input terminal exceeds a reference voltage Vref1 connected to the inverting input terminal thereof, and a timer TM1 that starts time-limiting operation on the output from the comparator CMP3 and switches the resistance value of the variable resistor portion 8 to the above prescribed resistance value for a certain period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a power supply device and a discharge lamp lighting device.

[0002]

2. Description of the Related Art FIG. 10 shows a conventional apparatus. In this conventional apparatus, a high-voltage pulse is generated by an igniter 5 to start the discharge of a discharge lamp LP such as an HID lamp, and the discharge starts. Then, the process shifts to the constant power control, and the discharge lighting device for stably lighting the discharge lamp LP is configured.

This discharge lamp lighting device converts a DC power supply 1 into a voltage required by the discharge lamp LP, and a DC-DC converter 3 and a low-frequency inverter 4 having a function of stably lighting the discharge lamp LP; MOSF of DC converter 3
A switching element Q1 composed of ET and switching elements Q2 to Q composed of MOSFETs of the low frequency inverter 4
A control circuit 7 for driving and controlling the control circuit 5; a control power supply circuit 6 including a constant voltage circuit comprising a series regulator for generating a substantially constant voltage in order to stably supply power to the control circuit 7; , DC power supply 1 and DC
And a lighting power switch 2 inserted between the DC converter 3.

In a DC-DC converter 3, a switching element Q1 connected to a DC power supply 1 via a primary winding N1 of a transformer T1 comprising a flyback transformer and a power switch 2 is driven from a switch drive terminal DQ1 of a control circuit 7. By being turned on and off by a signal, a current is intermittently supplied to the primary winding N1 of the transformer T1, and a secondary output voltage corresponding to the turn ratio is generated in the secondary winding N2 of the transformer T1 by the intermittent driving. This secondary output voltage is rectified by a diode D1 and smoothed by a capacitor C1 to output a DC voltage.

The low-frequency inverter 4 has a switching element Q
2 and a series circuit of Q4 and a series circuit of switching elements Q3 and Q5 are connected between output terminals of the DC-DC converter 3, and an igniter 5 and a discharge lamp LP serving as a load circuit are connected between the midpoints of the respective series circuits. The switching elements Q2 and Q5 are output from the switch driving terminals DQ2 to DQ5 of the control circuit 7 in response to low-frequency driving signals corresponding to the switching elements Q2 to Q5.
Are turned on and off at the same time, and the switching elements Q3 and Q4 are turned off when the switching elements Q2 and Q5 are turned on, and turned off when the switching elements Q2 and Q5 are turned on, so that the igniter 5 and the discharge lamp LP have low-frequency AC. (Rectangular wave) voltage is applied.

The control circuit 7 operates by receiving a power supply from the control power supply circuit 6, and operates at a voltage between the output terminals of the DC-DC converter 3, that is, the discharge lamp LP via the low-frequency inverter 4.
Of DC voltage (lamp voltage) Vla and DC-DC
Lamp current value Ila detected from the voltage drop of resistor R1 inserted between converter 3 and low-frequency inverter 4.
By controlling the switching of the switching element Q1 of the DC-DC converter 3 and the switching of the switching elements Q2 to Q5 of the low-frequency inverter 4 on the basis of The output is supplied from the low frequency inverter 4 to the load circuit side.

[0007] Vin is a DC power supply voltage detection terminal for detecting the voltage E1 of the DC power supply 1, and Vcc indicates a power supply voltage supplied from the control power supply circuit 6 to the power supply terminal.

Next, the operation principle of the conventional control power supply circuit 6 will be described.

First, when the DC power supply 1 is turned on by the power switch 2, the base of the control transistor Q6 of the series regulator of the control power supply circuit 6 via the primary winding N1 of the transformer 1 of the DC-DC converter 3 and the diode D2. Is supplied with a base current determined by the resistor R2, and the control transistor Q
The emitter current Ie supplied to the emitter No. 6 is determined.

The emitter current Ie charges the capacitor C3 and, at the same time, controls the control circuit 7 via a power supply terminal of the control circuit 7.
Is the current that is input to and consumed.

The emitter current Ie causes the capacitor C
3 is charged, and when the charging voltage, that is, the power supply voltage Vcc supplied to the control circuit 7 reaches the operating voltage Vst at which the control circuit 7 operates normally and stably, the control circuit 7 starts operating and performs each switching operation. A drive signal is output from the switch drive terminals DQ1 to DQ5 to the elements Q1 to Q5,
-Start the operation of the DC converter 3 and the low-frequency inverter 4.

In the configuration of the control power supply circuit 6 shown, when the voltage E1 of the DC power supply 1 is low, the base current flowing through the control transistor Q6 is small, so that the emitter current Ie is small. If the emitter current Ie is small, the current required by the control circuit 7 cannot be sufficiently secured.
The control circuit 7 does not operate normally.

Therefore, by reducing the resistance R2, even when the voltage E1 of the DC power supply 1 is low, the emitter current Ie increases, and the operating voltage Vst at which the control circuit 7 operates normally and stably can be secured in the capacitor C3. .

The operation of the control power supply circuit 6 after the control circuit 7 has shifted to a stable operation is as follows.

First, after shifting to the stable operation of the control circuit 7,
When the switching element Q1 of the DC-DC converter 3 is turned off, the energy stored in the primary winding N1 of the transformer T1 flows into the capacitor C2 via the diode D2 in the control power supply circuit 6, so that the DC power supply 1 The voltage VC2 higher than the voltage E1 is charged.

To stably operate the control circuit 7,
Capacitor C2 → Collector of control transistor Q6 →
The charging current flows from the capacitor C2 to the capacitor C3 through the path of the emitter of the control transistor Q6, and charges the capacitor C3 to a voltage lower than at least the voltage VC2 defined by the Zener diode ZD1.

If necessary, the capacitor C3 is charged through the path of the capacitor C2 → the base of the control transistor Q6 → the emitter of the control transistor Q6.

At this time, if the Zener voltage of Zener diode ZD1 is VZD1, VC
The voltage determined by 2-VZD1 is applied.

[0019]

In the conventional control power supply circuit 6, when the resistance R2 is reduced as described above, after the stable operation starts, the VC2-
Considering that the voltage determined by VZD1 is applied to both ends of the resistor R2, the current consumed by the resistor R2 increases when the resistor R2 is small.

As a result, the current flowing through the Zener diode ZD1 increases, so that the heat generated by the resistor R2 and the Zener diode ZD1 increases, and the circuit loss increases.

As a result, it is necessary to select a component having a higher rating than the result, which causes a problem that the size of the component is increased and the cost is increased.

The present invention has been made in view of the above-described problems, and has as its object the purpose of ensuring that the control circuit operates normally and stably even when the power is turned on or when the power supply voltage is low. An object of the present invention is to provide a power supply device capable of securing a voltage.

[0023]

In order to achieve the above object, according to the first aspect of the present invention, a DC power supply and a switching element connected to the DC power supply are turned on and off so that a voltage from the DC power supply is changed to a load voltage. DC-DC to be converted to
To connect a smoothing capacitor to both ends of the switching element via a converter and a rectifying element for rectifying a voltage applied to the switching element, and to regulate the voltage of the capacitor to a control transistor and an output voltage to a predetermined voltage. A series regulator composed of a Zener diode connected to the base of the control transistor and an impedance element for supplying a base current to the base of the control transistor; And a constant voltage generating circuit for supplying a control voltage to the control circuit for controlling the impedance value of the impedance element.

According to a second aspect of the present invention, in the first aspect, the impedance value of the impedance element is
It is characterized in that the value is changed to a value lower than the steady value for a predetermined time from when the power is turned on.

According to a third aspect of the present invention, in the first aspect of the present invention, the impedance value of the impedance element is changed to a value lower than a steady value when the output voltage of the constant voltage generating circuit is lower than the predetermined voltage. And

According to a fourth aspect of the present invention, in the first aspect of the present invention, the impedance value of the impedance element is
When the voltage generated in the capacitor is lower than a predetermined voltage, the voltage is changed to a value lower than a steady value.

According to a fifth aspect of the present invention, in the first to fourth aspects of the present invention, a series circuit of a first resistor, a second resistor connected in parallel to the first resistor, and a switch element is provided as the impedance element. The impedance value of the impedance element is varied by turning on and off the switch element.

According to a sixth aspect of the present invention, in the first aspect of the present invention, the impedance element is constituted by a constant current circuit.

According to a seventh aspect of the present invention, in the sixth aspect, the constant current value of the constant current circuit is varied.

According to an eighth aspect of the present invention, in the sixth aspect of the present invention, the constant current value of the constant current circuit is set to a value larger than a steady value for a predetermined time after power-on.

According to a ninth aspect of the present invention, in the sixth aspect of the present invention, the constant current value of the constant current circuit is changed to a value larger than a steady value when the output voltage of the constant voltage generation circuit is lower than the predetermined voltage. It is characterized by the following.

According to a tenth aspect, in the sixth aspect, the constant current value of the constant current circuit is changed to a value larger than a steady value when the voltage generated in the capacitor is lower than a predetermined voltage. Features.

According to an eleventh aspect of the present invention, in the first aspect of the present invention, when the output voltage of the constant voltage generating circuit reaches a predetermined voltage lower than at least a voltage required for a steady operation of the control circuit, the DC-DC The switching element of the converter is turned on and off.

According to a twelfth aspect of the present invention, in the eleventh aspect of the present invention, at least two switching elements connected in series between the output terminals of the DC-DC converter are alternately turned on and off, thereby providing an AC output to the load circuit. And the switching elements of the inverter are turned off until the output voltage of the constant voltage generation circuit reaches a predetermined voltage required at the time of steady operation of the control circuit when power is turned on. .

According to a thirteenth aspect of the present invention, in the twelfth aspect of the present invention, when the power supply is turned on, the output voltage of the constant voltage generation circuit is maintained until the output voltage of the constant voltage generation circuit reaches a voltage required during a steady operation of the control circuit. The voltage is converted to a voltage lower than the voltage of the DC power supply so that the control circuit operates stably and the power is supplied to the control circuit.

According to a fourteenth aspect of the present invention, there is provided the power supply device according to any one of the first to thirteenth aspects, and the DC-DC
It is characterized by comprising an inverter for converting the output of the converter into AC and lighting the discharge lamp.

[0037]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.

(Embodiment 1) FIG. 1 shows a configuration of a main part of the present embodiment, in which a base current flows through a control transistor Q6 of a control power supply circuit 6 constituted by a constant voltage generating circuit composed of a series regulator. The variable resistance section 8 is a resistor as an impedance element for the
The control circuit 7 is characterized in that a control function for variably controlling the resistance value of the power supply switch 2 to a predetermined resistance value lower than the resistance value when the power switch 2 is turned on for a certain period of time is provided in the control circuit 7.

The structure of the DC-DC converter 3 and the DC
Circuits subsequent to the DC converter 3 are based on the conventional example shown in FIG. 10, and constitute a discharge lamp lighting device as a whole. In FIG. 1, illustration of a circuit subsequent to the DC-DC converter 3 is omitted. DC-DC converter 6
Since the configuration of the drive control function of the control circuit 7 for driving the switching element Q1 and the switching elements Q2 to Q6 (see FIG. 10) of the low-frequency inverter 7 (see FIG. 10) conforms to the conventional example, the description thereof is omitted.

The control function of the control circuit 7 for varying the resistance value of the variable resistance section 8 is such that a non-inverting input terminal is connected to the DC power supply 1 via the power switch 2 and an input is provided to the non-inverting input terminal. The comparator C generates an output when the voltage to be applied exceeds the reference voltage Vref1 connected to the inverting input terminal.
MP1 and a timer TM1 that starts a timed operation by the output of the comparator CMP1 and switches the resistance value of the variable resistance unit 8 to the above-mentioned predetermined resistance value for a certain period of time. The reference voltage Vref1 is set lower than the voltage E1 of the DC power supply 1 by a predetermined voltage.

Next, the operation of this embodiment will be described.

When the power switch 2 is turned on and the voltage E1 of the DC power supply 1 is input to the non-inverting input terminal of the comparator CMP1 via the DC power supply voltage detection terminal Vin,
The output of the comparator CMP1 changes from "L" level to "H".
In response to this output, the timer TM1 starts a timed operation and sets the output to the "H" level for a certain period of time. During the period when the output of the timer TM1 is at the "H" level, the variable resistance section 8 changes its resistance value to a predetermined resistance value lower than the steady state resistance value.
At the L level, the resistance is changed to a steady state resistance value.

With the above operation, after the power is turned on, the resistance value of the variable resistance section 8 becomes lower than the steady state value for a predetermined time, so that the problem described in the conventional example can be solved.

That is, even when the voltage E1 of the DC power supply 1 is somewhat lower (of course, higher than the reference voltage Vref1), the resistance value of the variable resistance section 8 is set to a low value when the power is turned on. A sufficient base current can be supplied to the control transistor Q6 of the circuit 6, and the power supply voltage Vcc of the control circuit 7 becomes the operating voltage Vst required for normal and stable operation for controlling the DC-DC converter 3. And the control circuit 7 starts operating.

As a result, the switching element Q1 of the DC-DC converter 3 starts an on / off operation, whereby the voltage of the capacitor C2 rises. After a predetermined time has passed, even if the variable resistor 8 is increased, the power supply voltage Vcc is sufficient. (A substantially constant voltage defined by the Zener diode ZD1).

As described above, in the present embodiment, the DC power supply E1
Circuit operation when the voltage is low is also possible, resulting in low circuit loss, high degree of freedom in component selection,
A power supply device (discharge lamp lighting device) that can achieve cost reduction and downsizing can be provided.

FIG. 2 shows a specific circuit example of the variable resistor section 8. The resistor R5 is connected between the collector and base of the control transistor Q6 of the control power supply circuit 6, and the resistor R6 and the PNP transistor Q7 are connected. Are connected, a NPN transistor Q8 is connected between the base of the transistor Q7 and the ground line, and a resistance switching signal is connected to the base of the transistor Q8. In this embodiment, the signal for switching the resistance value is constituted by the output of the timer TM1. When this output is at the "H" level, the transistors Q8 and Q7 are turned on, and the resistance R5
And a parallel circuit of R6 are connected between the collector and base of the control transistor Q6.

When the output of the timer TM1 becomes "L" level, the transistors Q8 and Q7 are turned off, and the resistor R5 is connected between the collector and the base of the control transistor Q6. That is, the resistance value when the resistor R6 is connected in parallel with the resistor R5 ((R5 · R6) / (R5
+ R6)), the resistance value between the collector and base of the control transistor Q6 becomes larger.

The specific circuit example shown in FIG. 2 is merely an example, and another variable resistance means may be employed as the variable resistance section 8.

(Embodiment 2) In the first embodiment, the resistance value of the variable resistance section 8 is set to be lower than that in the steady state for a certain period of time after the power is turned on. 8 from the control power supply circuit 6 to the control circuit 7
Is characterized in that it can be varied in accordance with the power supply voltage Vcc input to the power supply terminal.

That is, in this embodiment, the power supply voltage Vcc of the control circuit 7 is compared with a predetermined reference voltage Vref2 by a comparator CMP2 provided in the control circuit 7 as shown in FIG. When the resistance is lower, the resistance value of the variable resistance unit 8 is changed to a value lower than the steady value by the output of the comparator CMP2. Here, reference voltage Vref2 is set to a predetermined voltage lower than a substantially constant output voltage defined by zener diode ZD1 output from control power supply circuit 6.

Immediately after the power switch 2 is turned on, the power supply voltage Vcc of the control circuit 7, which is the voltage of the capacitor C3 of the control power supply circuit 6, is equal to the Zener diode Z.
The reference voltage vr is lower than the voltage defined by D1.
Since it is lower than f2, the output of the comparator CMP2 is at "L" level. The output of the comparator CMP2 is inverted by the NOT gate NOT1 and input to the variable resistance unit 8. The variable resistance section 8 changes the resistance value to a predetermined value lower than the value in a steady state while the “H” level signal is being input. As a result, the emitter current Ie of the control transistor Q6 increases, and the voltage of the capacitor C3, that is, the power supply voltage Vcc of the control circuit 7 rapidly rises to a substantially constant predetermined voltage defined by the Zener diode ZD1.

In this case, before reaching the predetermined voltage, the reference voltage Vref2 is reached, and the output of the comparator CMP2 is inverted from "L" level to "H" level. As a result, the variable resistance section 8 changes the resistance value to a steady value. However, since the time required for the voltage of the capacitor C3 to exceed the reference voltage Vref2 and reach the predetermined voltage is extremely short, the problem of shortening the time required to reach the predetermined voltage can be achieved.

When the voltage E1 of the DC power supply 1 is low,
The time required for the voltage of the capacitor C3 to exceed the reference voltage Vref2 increases, but during that time, the variable resistance section 8 maintains a low resistance value. On the other hand, when the voltage E1 of the DC power supply 1 is high, the voltage of the capacitor C3 becomes equal to the reference voltage Vref2.
, And the resistance value of the variable resistance section 8 can be quickly brought to a steady value.

As described above, in the present embodiment, the timing at which the resistance value of the variable resistance section 8 is varied according to the voltage E1 of the DC power supply 1 is changed. Section 8 and Zener diode Z
The stress of D1 can be reduced, and a small power supply device with low loss can be provided. Further, the switching element Q1 of the DC-DC converter 3 depends on the state of the load circuit.
This embodiment is effective when the on / off operation of the discharge lamp decreases (for example, until the discharge lamp is lit by the discharge lamp lighting device (substantially no load)).

The circuit shown in FIG. 2 may be employed as the variable resistance section 8. In this case, the output signal of the NOT gate NOT1 is input to the base of the transistor Q8. Of course, other variable resistance means may be employed. DC-DC
Circuits downstream of the converter 3 are based on the conventional example, and illustration and description are omitted here.

(Third Embodiment) In the second embodiment, the resistance value of the variable resistance section 8 is varied according to the voltage of the capacitor C3 of the control power supply circuit 6, that is, the power supply voltage Vcc of the control circuit 7. The present embodiment is characterized in that the resistance value of the variable resistance section 8 is varied according to the voltage VC2 of the capacitor C2 of the control power supply circuit 6.

That is, in this embodiment, as shown in FIG. 4, a comparator CMP3 provided in the control circuit 7 compares the voltage VC2 of the capacitor C2 of the control power supply circuit 6 with a predetermined reference voltage Vref3, and the voltage VC2 Voltage Vr
When it is lower than ef3, the resistance value of the variable resistance unit 8 is changed to a value lower than the steady value by the output of the comparator CMP3. Here, the reference voltage Vref3 is
For example, the voltage of the capacitor C2 in a steady state is set.

Immediately after the power switch 2 is turned on, the voltage VC of the capacitor C2 of the control power circuit 6 is
2 is lower than the reference voltage vrf3, the output of the comparator CMP3 is at "L" level. At this time, the output of the comparator CMP3 is inverted by the NOT gate NOT2 and input to the variable resistance unit 8. Variable resistance section 8 is "H"
While the level signal is being input, the resistance value is varied to a predetermined value lower than the value in a steady state. As a result, the emitter current Ie of the control transistor Q6 increases, and the voltage of the capacitor C3, that is, the power supply voltage Vcc of the control circuit 7 rapidly rises to a substantially constant predetermined voltage defined by the Zener diode ZD1.

The capacitor C2 is connected to the reference voltage Vref
3, the output of the comparator CMP3 is inverted from “L” level to “H” level, and as a result, the
Changes the resistance value to a steady value.

As described above, in this embodiment, the power supply voltage Vcc necessary for the control circuit 7 to operate stably can be obtained more reliably.

The circuit shown in FIG. 2 may be employed as the variable resistance section 8. In this case, the output signal of the NOT gate NOT2 is input to the base of the transistor Q8. Of course, other variable resistance means may be employed. DC-DC
Circuits downstream of the converter 3 are based on the conventional example, and illustration and description are omitted here. (Embodiment 4) In Embodiments 1 to 3, the control power supply circuit 3
The variable resistance section 8 is connected between the collector and the emitter of the control transistor Q6 of the series regulator of
The present embodiment is characterized in that the constant current circuit 9 supplies the base current of the control transistor Q6 as shown in FIG. The value of the constant current I1 output from the constant current circuit 9 is used as the power supply voltage Vcc of the control circuit 7, and the current amplification factor of the control transistor Q6 for obtaining the operating voltage Vst necessary for obtaining a normal stable operation. The value is larger than one-half.

The constant current I1 output from the constant current circuit 9
As a result, the base current can be sufficiently supplied to the control transistor Q6, so that the operation voltage Vst can be supplied to the control circuit 7 even when the voltage E1 of the DC power supply 1 is low.

Since the circuit loss increases as the value of the constant current I1 output from the constant current circuit 9 increases, it is preferable to set the value to a low value while satisfying the above conditions. Circuits subsequent to the DC-DC converter 3 shall conform to the conventional example,
Here, illustration and description are omitted. (Embodiment 5) The present embodiment is characterized in that a constant current circuit 9 'capable of changing the value of the current output from Embodiment 4 is provided.

That is, in the case of the fourth embodiment, since the output current of the constant current circuit 9 is fixed at I1, even when the power supply voltage Vcc of the control circuit 7 is low, the emitter current Ie of the control transistor Q6 in the steady state is maintained. The charging of the capacitor C3 is restricted to a value close to the value, and is defined as constant current charging. Therefore, the control circuit 7
Is low, it is difficult to quickly increase the voltage to the voltage specified by the Zener diode ZD1.

Therefore, in the present embodiment, as shown in FIG. 6, the power supply voltage Vcc of the control circuit 7 is compared with a predetermined reference voltage Vref4 by a comparator CMP4 provided in the control circuit 7, and the power supply voltage Vcc is set to the reference voltage Vref4. When the output is lower, the constant current value output from the constant current circuit 9 is changed to a predetermined constant current value that is larger than the steady state value by the output of the comparator CMP4.

Immediately after the power switch 2 is turned on, the power supply voltage Vcc of the control circuit 7, which is the voltage of the capacitor C 3 of the control power supply circuit 6, is equal to the Zener diode Z.
Reference voltage Vrf lower than the voltage defined by D1
4, the output of the comparator CMP4 is "
Accordingly, the constant current circuit 9 'supplies a constant current having a value larger than the steady-state current I1 to the base of the control transistor Q6. Accordingly, the emitter current Ie of the control transistor Q6 changes. Increase and capacitor C3
, That is, the power supply voltage Vcc of the control circuit 7 quickly rises to a substantially constant predetermined voltage defined by the Zener diode ZD1.

As described above, in the present embodiment, when the power supply voltage Vcc at the time of power-on is low as described above, the control circuit 7 can operate quickly by increasing the emitter current Ie of the control transistor Q6. Supply voltage Vc to voltage Vst
It is possible to provide a power supply device (discharge lamp lighting device) capable of increasing c.

In this embodiment, the constant current value output from the constant current circuit 9 'is made variable by the value of the power supply voltage Vcc of the control circuit 7. However, as in the first and third embodiments, the voltage of the DC power supply 1 is changed. The value and the voltage V of the capacitor C2 of the control power supply circuit 6
Needless to say, the same effect can be obtained even if the constant current value is varied according to the value of C2.

The circuits subsequent to the DC-DC converter 3 are based on the conventional example, and the illustration and description are omitted here.

(Embodiment 6) In the first to third embodiments, the resistance connected between the collector and the base of the control transistor Q6 of the control power supply circuit 6 is made variable. In the fifth embodiment, the current flowing to the base of the transistor Q6 is made constant, and in the fifth embodiment, the current flowing to the base of the control transistor Q6 of the control power supply circuit 6 is made constant and the value is variable. In the embodiment, the control of the switching element Q1 of the DC-DC converter 3 is optimized when the power is turned on, and even when the voltage E1 of the DC power supply 1 is low, the voltage Vst at which the control circuit 7 operates normally and stably is controlled by the control power supply circuit. 6 is characterized in that it is sufficiently secured.

That is, in this embodiment, as shown in FIG. 7, the configuration of the control power supply circuit 6 is the same as that of the conventional example shown in FIG. A comparator CMP5 for comparing the output voltage from the power supply circuit 6 (the power supply voltage Vcc of the control circuit 7) with the reference voltage Vref5 is provided, and the output of the comparator CMP5 and the output from the drive signal generator SG of the switching element Q1 are output. An AND gate AND1 for obtaining a logical product with the pulse signal is provided, and the output of the AND gate AND1 is output as a drive signal for the switching element Q1 of the DC-DC converter 3.

Here, the reference voltage Vref5 is set to a voltage lower than the voltage Vst at which the control circuit 7 operates normally.

When the power switch 2 is turned on and the power supply voltage Vcc supplied from the control power supply circuit 6 to the control circuit 7 reaches the reference voltage Vref5, the comparator CMP5
Inverts the output from "L" level to "H" level.

As a result, the pulse signal of the drive signal generator SG is supplied from the AND gate AND 1 to the DC-DC converter 3.
As a drive signal for the switching element Q1. Here, the drive signal generator SG is connected to the power supply voltage Vcc.
Starts its operation before the reference voltage Vref5 reaches the reference voltage Vref5. The output of the comparator CMP5 is inverted to the "H" level, and at the same time, a drive signal is output to the switching element Q1 via the AND gate AND1. On the other hand, since the function in the control circuit 7 for generating the drive signals for the switching elements Q2 to Q5 of the low-frequency inverter 4 does not operate until it rises to the operating voltage Vst, even if the switching element Q1 starts switching. At that time, it is in a stopped state.

By operating the switching element Q1 of the DC-DC converter 3 at a voltage level lower than the operating voltage Vst of the control circuit 7, the energy stored in the primary winding N1 of the transformer T1 when the switching element Q1 is off. Of the capacitor C2 flows into the capacitor C2 via the diode D2 to be charged, and the voltage of the capacitor C2 is increased.

By the voltage charged in the capacitor C2, the normal operation voltage Vst is sufficiently secured as the power supply voltage Vcc of the control power supply circuit 6, and a stable circuit starting operation can be obtained even when the voltage of the DC power supply 1 is low. . (Embodiment 7) In this embodiment, in addition to the configuration of Embodiment 6, the power supply voltage Vcc of the control circuit 7 is changed to the operating voltage Vst.
In the lower case, a circuit for controlling the switching elements Q2 to Q5 of the low-frequency inverter 4 to be turned off while the switching element Q1 of the DC-DC converter 3 is switching is added.

That is, in the sixth embodiment, considering the operation at the time of turning on the power, the switching element Q1 first starts switching before the power supply voltage Vcc reaches the operating voltage Vst as described above. By starting the switching, energy is transmitted to the secondary side of the transformer T1 while the switching element Q1 is on.
At this time, the switching elements Q2 and
When Q5 or any of Q3 and Q4 is in the ON state, the voltage Vig1 is generated at the input terminal of the igniter 5. Here, since the igniter 5 generates a pulse, the igniter 5
If Vig1 reaches Vig2, a pulse is applied from the igniter 5 to the discharge lamp LP, and the discharge lamp LP starts discharging. At the start of the lighting, the output power of the power supply becomes maximum, and accordingly, the input power is required.

At this time, the voltage E1 of the DC power supply 1 becomes Vcc <
When the switching element Q1 is in a state low enough to start switching at Vst, an excessive input current flows, and the occurrence of power supply chattering causes the capacitor C3
It is conceivable that the voltage required for stable operation of the control circuit 7 is not secured.

On the other hand, in the present embodiment, the power supply voltage Vc
c and the reference voltage Vref6 (= Vst), and when the power supply voltage Vcc reaches the reference voltage Vref6, “
A comparator CMP6 for generating an H-level output;
Until the "H" level output of the comparator CMP6 is input, the switching elements Q2 to Q
And an OFF command circuit 10 for outputting a command to maintain the OFF state of the switching element 5 to the drive signal generation circuit 11 by maintaining the switching elements Q2 to Q5 OFF until the power supply voltage Vcc of the control circuit 7 reaches the operating voltage Vst. It is characterized in that the problem caused by the power chattering can be solved. The drive signal generation circuit 11 is a circuit for generating a drive signal for each of the switching elements Q2 to Q5, and starts operating when the above-mentioned OFF command is lost.

In this embodiment, the switching elements Q2 to Q5 of the low-frequency inverter 4 start switching when the power supply voltage Vcc reaches the operating voltage Vst.
Thus, a stable operation can be obtained at the time of starting the circuit when the power supply voltage Vcc rises slowly.

(Eighth Embodiment) In the circuit configuration of the sixth embodiment, the power supply voltage Vcc
Is a DC power supply 1 input to the DC power supply voltage detection terminal Vin.
Is lower than the voltage E1 of the power supply voltage Vcc, the power supply voltage Vcc performs a stable operation of the circuit unit including the comparator CMP5, the AND gate AND1, and the drive signal generation unit SG provided for detecting the power supply voltage Vcc and controlling the switching of the switching element Q1. When the voltage is lower than the voltage Vcca, the circuit section is not stabilized, and the detection of the power supply voltage Vcc and the driving of the switching element Q1 are not performed accurately.

Therefore, in the present embodiment, in addition to the configuration of the sixth embodiment, as shown in FIG. 9, a stable state for more reliably detecting the power supply voltage Vcc and switching the switching element Q1 of the DC-DC converter 3 is realized. It is obtained by adding a conversion circuit 12.

In other words, immediately after the power is turned on, until the discharge lamp lighting circuit including the DC-DC converter 3 and the low-frequency inverter 4 starts to operate stably, the voltage of the DC power supply 1 input from the DC power supply voltage detection terminal Vin is applied. In this embodiment, E1 is stabilized to a predetermined voltage Vcca by the stabilization circuit 12 and supplied to the circuit unit A including the comparator CMP5, the AND gate AND1, and the drive signal generation unit SG. As a result, the detection of the power supply voltage Vcc and the driving of the switching element Q1 can be performed accurately.

[0085]

According to the first aspect of the present invention, a DC power supply and a switching element connected to the DC power supply are turned on and off to convert a voltage from the DC power supply into a load voltage.
A smoothing capacitor is connected to both ends of the switching element via a C-DC converter and a rectifying element for rectifying a voltage applied to the switching element, and the voltage of the capacitor is changed to a control transistor and the output voltage is set to a predetermined voltage. A Zener diode connected to the base of the control transistor to define, by a series regulator consisting of an impedance element for supplying a base current to the base of the control transistor, is converted to the substantially constant predetermined voltage, A constant voltage generating circuit for supplying a control circuit for controlling the switching element, wherein the power supply device varies the impedance value of the impedance element, so that the base current of the control transistor is varied and output from the control transistor. In-variable current Can, as a result the power is turned on or the DC power supply control circuit even when the voltage is low there is an effect of making it possible to quickly secure an operating voltage to operate stably.

According to a second aspect of the present invention, in the first aspect of the present invention, the impedance value of the impedance element is changed to a value lower than a steady value for a predetermined time after power-on, so that the voltage of the smoothing capacitor is low. The voltage at which the control circuit operates stably at power-on can be secured quickly, and as a result, a stable operation at circuit start-up is obtained. The circuit loss can be reduced as compared with the case where the impedance value is always set to a low value. Therefore, the degree of freedom in selecting the parts to be used is increased, and the cost and the size of the device can be reduced.

According to a third aspect of the present invention, in the first aspect of the invention, the impedance value of the impedance element is changed to a value lower than a steady value when the output voltage of the constant voltage generating circuit is lower than the predetermined voltage. It is possible to quickly secure the voltage at which the control circuit can operate stably even when the power is turned on or when the voltage of the DC power supply is low, and to reduce the circuit loss without causing any circuit loss. This has the effect of increasing the degree of freedom in selection of the device and reducing the cost and the size of the device.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the impedance value of the impedance element is changed to a value lower than a steady value when the voltage generated in the capacitor is lower than a predetermined voltage. This is particularly effective when the switching operation of the transistor of the DC converter changes according to the state of the load circuit and the voltage of the smoothing capacitor cannot be sufficiently obtained.

According to a fifth aspect of the present invention, in the first to fourth aspects, a series circuit of a first resistor, a second resistor connected in parallel to the first resistor, and a switch element is provided as the impedance element. Since the impedance value of the impedance element is varied by turning on and off the switch element, there is an effect that an impedance element capable of varying the impedance value can be realized with a simple configuration.

According to a sixth aspect of the present invention, in the first aspect of the present invention, since the impedance element is constituted by a constant current circuit, a voltage at which the control circuit operates stably even when the voltage of the DC power supply is low can be secured. This has the effect.

According to a seventh aspect of the present invention, in the sixth aspect of the present invention, the constant current value of the constant current circuit is varied, so that the control circuit operates stably even when the power is turned on or when the DC power supply voltage is low. Can be secured.

According to an eighth aspect of the present invention, in the sixth aspect of the present invention, the constant current value of the constant current circuit is set to a value larger than a steady value for a predetermined time after power-on, and is particularly effective at power-on. In addition, there is an effect that the circuit loss in a steady state is not increased.

According to a ninth aspect of the present invention, in the sixth aspect of the present invention, the constant current value of the constant current circuit is changed to a value larger than a steady value when the output voltage of the constant voltage generating circuit is lower than the predetermined voltage. Therefore, there is an effect that a voltage at which the control circuit operates stably can be secured quickly when the power is turned on or when the DC power supply voltage is low.

According to a tenth aspect, in the sixth aspect, the constant current value of the constant current circuit is changed to a value larger than a steady value when the voltage generated in the capacitor is lower than a predetermined voltage. This is particularly effective when the switching operation of the transistor of the DC-DC converter changes according to the state of the load circuit and the voltage of the smoothing capacitor cannot be sufficiently obtained.

According to an eleventh aspect of the present invention, in the first aspect of the present invention, when the output voltage of the constant voltage generating circuit reaches a predetermined voltage lower than at least a voltage necessary for a steady operation of the control circuit, the DC-DC Since the switching element of the converter is turned on and off, there is an effect that even when the voltage of the DC power supply is low, a voltage at which the control circuit can operate stably can be obtained.

According to a twelfth aspect of the present invention, in accordance with the eleventh aspect of the present invention, at least two switching elements connected in series between the output terminals of the DC-DC converter are alternately turned on and off to output an AC output to the load circuit. Since each switching element of the inverter is turned off until the output voltage of the constant voltage generation circuit reaches a predetermined voltage required at the time of steady operation of the control circuit when the power is turned on, the constant voltage generation circuit is provided. There is an effect that stable operation can be achieved even when the output voltage of the circuit gradually rises.

According to a thirteenth aspect of the present invention, in the twelfth aspect of the present invention, when the power supply is turned on, the output voltage of the constant voltage generating circuit reaches a required voltage during a steady operation of the control circuit. Since the control circuit operates stably and converts the voltage to a voltage lower than the voltage of the DC power supply and uses the voltage as the power supply of the control circuit, the operation of the control circuit is performed from the time the power supply is turned on until the device circuit stably operates. There is an effect that it can be performed accurately.

According to a fourteenth aspect of the present invention, there is provided the power supply according to any one of the first to thirteenth aspects, and an inverter for converting the output of the DC-DC converter of the power supply into an alternating current and lighting the discharge lamp. Therefore, it is possible to provide a discharge lamp lighting device utilizing the features of the power supply device according to any one of claims 1 to 13.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a main part according to a first embodiment of the present invention.

FIG. 2 is a specific circuit example diagram of the variable resistor unit according to the first embodiment.

FIG. 3 is a circuit diagram of a main part according to a second embodiment of the present invention.

FIG. 4 is a circuit diagram of a main part according to a third embodiment of the present invention.

FIG. 5 is a circuit diagram of a main part according to a fourth embodiment of the present invention.

FIG. 6 is a circuit diagram of a main part according to a fifth embodiment of the present invention.

FIG. 7 is a circuit diagram according to a sixth embodiment of the present invention.

FIG. 8 is a circuit diagram according to a seventh embodiment of the present invention.

FIG. 9 is a circuit diagram according to an eighth embodiment of the present invention.

FIG. 10 is a circuit diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DC power supply 2 Power switch 3 DC-DC converter 6 Control power supply circuit 7 Control circuit 8 Variable resistance part T1 Transformer Q1 Switching element CMP1 Comparator Vref1 Reference voltage TM1 Timer Q6 Control transistor D2 Diode C2, C3 Capacitor ZD1 Zener diode Vcc Power supply voltage Vin DC power supply voltage detection terminal

Continued on the front page F term (reference) 3K083 AA88 BA04 BA25 BA26 BA47 BC33 BD03 BD04 BD16 BE12 BE28 CA31 CA32 5H007 BB03 CA02 CB07 CC32 DA06 DB09 DC05 GA01 5H730 AS11 BB43 DD04 EE07 FD11 VV06 XX09

Claims (14)

[Claims] A DC-DC converter for converting a voltage from a DC power supply into a load voltage by turning on and off a DC power supply, a switching element connected to the DC power supply, and a rectifier for rectifying a voltage applied to the switching element. A capacitor for smoothing is connected to both ends of the switching element via an element, and the voltage of the capacitor is
A series regulator comprising a control transistor, a zener diode connected to the base of the control transistor to regulate the output voltage to a predetermined voltage, and an impedance element for supplying a base current to the base of the control transistor, A constant voltage generation circuit that converts the voltage to the predetermined voltage and supplies the voltage to a control circuit that controls the switching element;
A power supply device characterized by varying an impedance value of the impedance element. 2. The power supply device according to claim 1, wherein the impedance value of the impedance element is changed to a value lower than a steady value for a predetermined time after power-on. 3. The power supply device according to claim 1, wherein the impedance value of said impedance element is varied to a value lower than a steady value when an output voltage of said constant voltage generation circuit is lower than said predetermined voltage. 4. The power supply device according to claim 1, wherein the impedance value of said impedance element is changed to a value lower than a steady value when a voltage generated in said capacitor is lower than a predetermined voltage. 5. An impedance element comprising a first resistor, a series circuit of a second resistor and a switch element connected in parallel to the first resistor, and turning on and off the switch element to form the impedance element. The impedance value of the impedance element is variable.
The power supply device according to any one of the above. 6. The power supply device according to claim 1, wherein said impedance element is constituted by a constant current circuit. 7. The power supply device according to claim 6, wherein a constant current value of said constant current circuit is varied. 8. The power supply device according to claim 6, wherein a constant current value of said constant current circuit is set to a value larger than a steady value for a predetermined time from power-on. 9. The power supply device according to claim 6, wherein a constant current value of said constant current circuit is changed to a value larger than a steady value when an output voltage of said constant voltage generation circuit is lower than said predetermined voltage. . 10. The power supply device according to claim 6, wherein a constant current value of said constant current circuit is changed to a value larger than a steady value when a voltage generated in said capacitor is lower than a predetermined voltage. 11. When the output voltage of the constant voltage generating circuit reaches a predetermined voltage lower than at least a voltage required for a steady operation of the control circuit, the switching element of the DC-DC converter is turned on / off. The power supply device according to claim 1, wherein: 12. An inverter for providing an AC output to a load circuit by alternately turning on and off at least two switching elements connected in series between output terminals of a DC-DC converter, wherein said constant voltage The power supply device according to claim 11, wherein each switching element of the inverter is turned off until the output voltage of the generation circuit reaches a predetermined voltage required during a steady operation of the control circuit. 13. When the power supply is turned on, until the output voltage of the constant voltage generation circuit reaches a voltage required during a steady operation of the control circuit, the voltage of the DC power supply is operated by the control circuit in a stable manner, and 13. The power supply for the control circuit, wherein the power supply is converted to a voltage lower than a voltage of a power supply.
The power supply as described. 14. A power supply unit according to claim 1, further comprising an inverter for converting an output of a DC-DC converter of the power supply unit into an alternating current to turn on a discharge lamp. Discharge lamp lighting device.