JPH061720B2 - Inverter device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an inverter device which converts a DC voltage into a high frequency voltage and supplies electric power to a discharge lamp.

[Prior Art] FIG. 10 shows an inverter device used as a discharge lamp lighting device. The discharge lamp lighting device uses a single-stone inverter circuit. An inverter circuit 1 for supplying electric power to the discharge lamp La by turning on / off the transistor Tr ₁ of the DC power source E ₁ and a control P for controlling the output of the inverter circuit 1 by changing the ON period of the transistor Tr _1.
The ON period of the transistor Tr ₁ changes depending on the magnitude of the reference voltage Vref. The higher the reference voltage Vref is, the longer the ON period of the transistor Tr ₁ is, so that the electric power is supplied to the discharge lamp La. It is becoming more and more.

When a discharge lamp such as a fluorescent lamp is turned on, a method of preheating a filament for a certain period of time and then discharging it is used.
In the example of the figure, the frequency f of the inverter circuit 1 is changed so that the capacitor C ₀ connected in parallel to the discharge lamp La is
By changing the impedance of, the current flowing through the filament is changed, and the preheating and discharge states are switched. That is, during the preheating period, the reference voltage Vref is lowered, the ON period of the transistor Tr ₁ is shortened, the frequency f is increased, the impedance of the capacitor C ₀ is lowered, and a current is passed through the filament, and after a certain time, reference voltage generating circuit 3 'gradually increased reference voltage Vref, continue to extend the oN period of the transistor Tr _1, continue to change towards lower frequencies f simultaneously, the discharge lamp La is lighted.
Also, when the impedance of the capacitor C ₀ becomes high,
Almost no current flows through the filament. After the discharge lamp La is turned on, in order to change its brightness, the reference voltage Vref is lowered and raised to change the frequency f of the inverter circuit 1 to create a dimming lighting full lighting state.

The transition from the preheating state to the lighting state of the discharge lamp La and the switching between the dimming lighting and the full lighting at the time of lighting change the reference voltage Vref as described above to change the ON period of the transistor Tr ₁ and the inverter circuit 1 The frequency f is changed. However, if the frequency f is switched abruptly, the resonance of the inverter circuit 1 may be disturbed and abnormal vibration may occur, which may damage the transistor Tr _1. Needs to be changed gradually. That is, it is necessary to gradually change the reference voltage Vref.

Therefore, the change in the reference voltage Vref for performing the full lighting dimming lighting by turning on the discharge lamp La after turning on the power is as shown in FIG. Such a reference voltage Vref
In order to obtain the change of the above, a reference voltage generating circuit 3'as shown in FIG. 10 has been conventionally used. In FIG. 11 (a), the reference voltage Vref output from the reference voltage generating circuit 3'is
FIG. 1 (b) shows the outputs of the inverter circuit 1, respectively.

When the power is turned on, the switch SW is in the off state, the comparator IC ₁ outputs the H level, the transistor Tr ₂ is turned on, and the reference voltage Vref is Then, as shown in FIG. 11 (a), a preheating state is established. When the capacitor C ₁ is charged through the resistor R ₁ and the charging voltage of the capacitor C ₁ becomes equal to or higher than the reference voltage E ₂ , the output of the comparator IC ₁ changes from H level to L level and the transistor Tr ₂ is turned off. As shown in FIG. 11 (a), the capacitors C ₂ and C ₃ are gradually charged (soft start), and the reference voltage Vref is Vref = Vcc · R ₅ / (R ₄ + R ₅ ). Until it reaches the full lighting state as shown in FIG. 11 (a).

After that, when the switch SW is turned on, the capacitor C ₃ ,
C ₂ is gradually discharged (soft switching), and the reference voltage Vref is It gradually descends to and becomes a dimming state. Then switch S
When W is turned off, the capacitors C ₃ and C ₂ are gradually charged, and the reference voltage Vref gradually increases until Vref = VccR ₅ (R ₄ + R ₅ ), and the full lighting state is resumed.

[Problems to be Solved] The reference voltage generating circuit 3 ', a capacitor C ₁ for setting at least the preheating _period, the capacitor C ₂ to gradually shift (soft-start) in the full lighting state from the preheating state And _three capacitors C3 for performing soft switching from full lighting to flood lighting or from dimming lighting to full lighting, and the control circuit unit including the reference voltage generation circuit 3'is integrated into an IC. In this case, there is a problem in that the number of external capacitors increases, which is not preferable.

The present invention has been made in view of the above points, and an object of the present invention is to provide an inverter device suitable for integrating a control circuit unit including a reference voltage generation circuit into an IC.

[Means for Solving the Problems] The present invention relates to a DC power supply, an inverter circuit that converts the voltage of the DC power supply into an AC voltage and supplies power to a discharge lamp,
An inverter including a control circuit that changes the output of the inverter circuit according to the magnitude of the reference voltage so as to increase when the reference voltage increases and conversely decreases when the reference voltage decreases, and a reference voltage generation circuit that generates the reference voltage. In the device, the reference voltage generating circuit, the capacitor, the charging circuit that charges this capacitor, the voltage dividing circuit that divides the power supply voltage of the reference voltage generating circuit to create a constant voltage, and the charging current of the capacitor by the charging circuit. The current switching means for switching and the first preheating for allowing the output of the voltage dividing circuit to be preheated without turning on the discharge lamp in the inverter circuit until the voltage across the capacitor reaches the first predetermined voltage. When the voltage is output as the reference voltage and the voltage across the capacitor reaches the first predetermined voltage, the current switching means increases the charging current of the capacitor and gradually increases it. The voltage across the capacitor, which increases substantially, is output as the second reference voltage for starting that generates a sufficient voltage for starting from the inverter circuit, and the charging voltage of the capacitor is the second predetermined voltage higher than the first predetermined voltage. Means for outputting a third reference voltage for lighting for generating a sufficient voltage for maintaining the lighting of the discharge lamp from the inverter circuit, and a series connection of the resistor and the switch element connected in parallel with the capacitor. When switching from full lighting to dimming lighting after lighting, by turning on the switch element, the voltage across the capacitor is gradually reduced to a predetermined dimming level in the discharge circuit, and from dimming lighting. When switching to full lighting, by turning off the switch element, the voltage across the capacitor is gradually increased to the second predetermined voltage by the charging circuit. And a discharge circuit for outputting a fourth reference voltage for the soft switching to switch the soft discharge lamp inverter circuit.

[Operation] With the configuration described above, the present invention changes the reference voltage according to the charging voltage of one capacitor to set the preheating period, the capacitor for soft start, all lighting and dimming. A single capacitor also serves as a soft switching function for lighting and the number of capacitors used in the reference voltage generation circuit is reduced, so that the circuit configuration is suitable for IC implementation.

Example 1 An example of the present invention will be described below with reference to the drawings. FIG. 1 shows a block circuit diagram in which the DC power supply E ₁ is converted into a high frequency by the inverter circuit 1 to supply power to the discharge lamp La. The output of the inverter circuit 1 is controlled by the control circuit 2. When the reference voltage Vref input to the control circuit 2 becomes high, the output of the inverter circuit 1 becomes high. The reference voltage generation circuit 3 that generates the reference voltage Vref includes resistors R _{1 to} R ₃ , a diode D ₁ , a capacitor C ₁ , and a comparator IC.
₁ , a constant current source 4, a switch SW _{1 and the} like.

Next, the operation of the reference voltage generating circuit 3 will be described. The second
FIG. 2 (a) shows the charging voltage Vc ₁ of the capacitor C ₁ , and FIG.
(b) shows the reference voltage Vref. When the switch SW ₁ is off and the power is turned on, the reference voltage Vref becomes Becomes The capacitor C ₁ starts charging, and the capacitor C _1
When the charging voltage Vc ₁ ≧ E ₂ (reference voltage of the comparator IC ₁ ) is satisfied, the comparator IC ₁ operates to switch the charging current i of the capacitor C ₁ to i ₁ . here,
By switching such that i ₁ > i, Vc ₁ rises faster.

on the other hand, So the _{Vref = Vc 1 -VD 1 (VD} 1 is the forward voltage drop of the diode _{D 1).} Therefore, the reference voltage E that determines the charging voltage Vc ₁ that switches the charging current i of the capacitor C ₁ to i _1.
2 , By selecting, the comparator IC ₁ operates and the charging of the capacitor C ₁ becomes faster, and at the same time, the reference voltage Vref
From _{Vcc · R 1 / (R 1} + R 2), Vc 1 -VD 1 next, as shown in FIG. 2 (a), the reference voltage Vref in response to an increase in the charge voltage Vc ₁ also continue to rise when raised to Vc ₁ = Vcc, it becomes constant becomes Vref = V _c1 -V _D1.

After that, when the switch SW ₁ is turned on, the capacitor C ₁
Is gradually discharged by the resistor R ₃ , and Vc ₁ = i ₁ R ₃
Becomes That is, the reference voltage Vref from Vcc-VD _1, i
It will vary gradually to ₁ R ₃ -VD _1.

Next, when the switch SW ₁ is turned off again, the capacitor C
₁ is recharged by the current i ₁ and the reference voltage Vre
f _is from i ₁ R 3 -VD _1, will change gradually to Vcc-VD _1. As shown in FIG. 2, Vref = Vcc ·
The state of R ₁ / (R ₁ + R ₂ ) is the preheating period, Vcc · Vc ₁ −
The period of VD ₁ is the soft start period, and Vref = Vcc-VD ₁
By making the state of _{No. 3} correspond to the full lighting state and the state of Vref = i ₁ R ₃ −VD ₁ to correspond to the dimming lighting state, a series of operations for lighting the discharge lamp La can be performed by one capacitor C _11. it can.

In this embodiment, the constant current source 4 is used as the charging circuit for charging the capacitor C ₁ , the voltage dividing circuit is composed of the resistors R ₁ and R ₂ , and the discharging circuit is composed of the resistor R ₃ and the switch SW _1. However, the comparator IC ₁ is used as the current switching means. Then, until the voltage across the capacitor C ₁ reaches the first predetermined voltage E ₂ , the output of the voltage dividing circuit is preheated by the inverter circuit 1 without causing the discharge lamp La to be lit. Output as reference voltage of 1 and capacitor C
_When the voltage across ₁ reaches the first predetermined voltage E ₂ , the charging current of the capacitor C ₁ is increased by the current switching means, and the gradually increasing voltage across the capacitor C ₁ is sufficient for starting from the inverter circuit 1. It is output as the second reference voltage for starting which generates a voltage, and the charging voltage of the capacitor C ₁ is the first
Reaches a _second predetermined voltage higher than the predetermined voltage E _{2 of}
A diode D ₁ is used as a means for outputting a third reference voltage for lighting (hereinafter, referred to as an output control means) for generating a voltage sufficient for maintaining the lighting of the discharge lamp La from the inverter circuit 1. .

The operation of this embodiment can be summarized as follows.
Until the voltage across the capacitor C ₁ reaches the first predetermined voltage E ₂ , a constant voltage (divided voltage by the resistors R ₁ and R ₂ ) is preheated by the inverter circuit 1 without lighting the discharge lamp La. The control circuit 2 is used as the first reference voltage for preheating.
Output to. When the voltage across the capacitor C ₁ reaches a first predetermined voltage E _2, the constant current source in the comparator IC ₁ 4 increases the charging current of the capacitor C ₁ by gradually substantially the voltage across the capacitor C ₁ to increase (Vc _1- VD ₁ ) is output from the inverter circuit 1 as the second reference voltage for starting which generates a sufficient voltage for starting. Furthermore, the charging voltage of the capacitor C ₁ reaches a first high second predetermined voltage than the predetermined voltage _{E 2 (Vcc-VD 1)} , the inverter circuit 1
Outputs a third reference voltage for lighting that generates a voltage sufficient to maintain the lighting of the discharge lamp La. When switching from all lighting to dimming lighting after lighting, by turning on the switch SW ₁ as a switch element, the voltage across the capacitor C ₁ is gradually lowered to a predetermined dimming level via the resistor R ₃ , and When switching from dimming lighting to all lighting, by turning off the switch SW ₁ , the voltage across the capacitor C ₁ is gradually increased to a second predetermined voltage (Vcc-VD ₁ ) by the constant current source 4, The inverter circuit 1 outputs the fourth reference voltage for soft switching for soft switching the discharge lamp La.

As described above, the reference voltage generating circuit 3 includes the capacitor C ₁ 1
Since it is composed of a capacitor, a resistor, and a semiconductor, when the control circuit part of the inverter is integrated into an IC, there is only one external capacitor, and other parts can be configured inside the IC. In comparison, the cost can be reduced. Therefore, the reference voltage generating circuit 3 of this embodiment is a circuit more suitable for IC than the conventional one. In addition, the reference voltage generation circuit 3 selects the constants of the resistors R ₁ and R ₂ , the currents i and i ₁ , the capacitor C ₁ , the diode D ₁ , the reference voltage E ₂ , and the resistor R ₃ to select the constants for the preheating timer and the soft start. Change speed of the reference voltage Vref, the reference voltage Vref during software switching
Is a circuit with a high degree of freedom, in which the changing speed, the reference voltage Vref during preheating, the reference voltage Vref during full lighting, and the reference voltage Vref during dimming lighting can be set arbitrarily and accurately.

[Embodiment 2] FIG. 3 shows Embodiment 2 in which a DC power supply E ₁ is a high frequency inverter circuit 1 including a coil L ₁ , a capacitor C ₂ , a current transformer CT, a transistor Tr ₁ and a diode D _1. And is supplied to the discharge lamp La. When the transistor Tr ₁ is turned on / off, vibrations are generated by L ₁ , C ₂ , L ₂ and the discharge lamps La, C ₀ , and a high frequency current flows through the discharge lamp La. Open collector output comparator IC ₁ , I
C ₂ constitutes a control circuit 2 for controlling the on period of the transistor Tr ₁ which is the main switch of the inverter circuit 1.

As shown in 4 (a), Karen becomes secondary voltage of the transformer CT is positive, when increases, the base of Torajisuta Tr ₁ current flows through the resistor R _1, Torajisuta Tr ₁ is Turn on. On the other hand, the comparator IC ₂ detects that the secondary voltage of the current lance CT has become positive, the output of the comparator IC ₂ changes from the L level to the H level, and as shown in FIG. C ₃ is the current i
Will be charged by. Charging voltage Vc ₃ of the capacitor _{C 3}
There becomes equal to or larger than the reference voltage Vref, as shown in FIG. 4 (c), the comparator IC ₁ changes from H level to L level, no longer flows the base current of Torajisuta Tr _1, Torajisuta Tr ₁ is turned off. When the transistor Tr ₁ is turned off, vibrations occur in the L ₁ , C ₁ , L ₂ discharge lamps La, C ₂ . During this period, when the secondary voltage of the current lance CT changes from positive to negative, the comparator IC ₂ changes from H level to L level, the capacitor C ₃ is discharged, and becomes OV. At the same time, the comparator IC ₁ changes from L level to H level. Further, when the secondary voltage of the current lance CT changes from negative to positive, the above operation is repeated and the inverter circuit 1 continues to operate at a constant frequency.

The current to the discharge lamp La can be changed by changing the frequency of the inverter circuit 1, and the frequency of the inverter circuit 1 can be changed by changing the ON period of the transistor Tr ₁ . Further, the ON period of the transistor Tr ₁ can be changed by changing the reference voltage Vref of the comparator IC ₁ . Therefore, the load (discharge lamp L
To change the current flowing to a), the reference voltage Vref may be changed. When the reference voltage Vref increases, the ON period of the transistor Tr ₁ increases, the frequency of the inverter circuit 1 decreases, and the current flowing through the discharge lamp La increases.

Next, the reference voltage generating circuit 3 will be described. The reference voltage generating circuit 3 uses only one capacitor C ₄ . FIG. 5 (a) shows the charging voltage of the capacitor C ₄ , and FIG. 5 (b) shows the reference voltage Vref. At power-on, the charging voltage VC ₄ of the capacitor _{C 4} is OV, the reference voltage Vrefp becomes _{Vref = Vcc · R 4 / (} R 3 + R 4). Charging current ics ₄ of the capacitor _{C 4,} the reference voltage _{E 2}
When the voltage between the base and emitter of the transistor Tr ₆ VBE ₆
And the resistance of transistors R _{6 to} R ₈
The capacitor C ₄ is charged through the current mirror circuit composed of r ₄ and Tr ₅ . When the power is turned on, the transistor Tr ₉ is off and Tr ₁₀ is on,
Charging current ics ₄ is iC ₄ = a _{(E 2 -VBE 6) / (} R 6 + R 7).

When the capacitor C ₄ continues to be charged and the charging voltage Vc ₄ ≧ E ₃ , the output of the comparator IC ₃ changes from the L level to the H level, the transistor Tr ₉ changes from the off state to the on state, and the preheating period increases. finish. At this time, the charging current ic ₄
Is, ics ₄ = increased _{(E 2 -VBE 6) / R} 6, the rising speed of the charging voltage Vc ₄ of the capacitor _{C 4} becomes faster. The reference voltage E ₃ of the comparator IC ₃ is If the output of the comparator IC ₃ changes from the L level to the H level, the reference voltage Vref = Vc ₄ − (VBE ₃ + VBE ₂ + VD ₂ ) is set, so that the reference speed is the same as that of VC _4. The voltage Vref also rises, the frequency of the inverter circuit 1 is gradually lowered, and the discharge lamp La can be changed from the preheated state to the fully lit state.

When the capacitor C ₄ is further charged and Vc ₄ = VZD ₁ + 2V _D + VBE ₃ , the current starts flowing through the Zener diode ZD ₁ , and thereafter, the base potential of the transistor Tr ₂ is VZD ₁ +2.
Since it is fixed to V _D, the reference voltage _{Vref, Vref = VZD 1 + 2V 2} -VBE 2 -VD 2 = VZD 1 next, is fixed to a constant voltage. The lighting state of the discharge lamp La, which is determined by the frequency of the inverter circuit 1 at this time, is the full lighting state. When a current flows through the zener diode ZD ₁ , the transistors Tr ₇ and Tr ₈ change from the off state to the on state, and the transistors Tr ₉ and Tr ₁₀ both turn from the on state to the off state. Therefore, the charging current of the capacitor C ₄ becomes _{ic 4 = (E 2 -VBE 6} ) reduced to _{/ (R 6 + R 7 +} R 8), the rising speed of Vc ₄ is delayed.

Further, the capacitor C ₄ continues to be charged, and Vc ₄ ≧ E ₄ (E ₄
Becomes the reference voltage of the comparator IC ₄ ), the output of the comparator IC ₄ changes from the L level to the H level, the transistor Tr ₁₁ is turned on, and the switch SW ₁ becomes operable. When the switch SW ₁ is off, Vref =
While continuing the full lighting state VZD _1, when the switch SW ₁ is turned on, Vc ₄ determined by Vc ₄ = iR _9, and the resistor _{R 9}
Thus, the reference voltage Vref is determined, and the reference voltage Vref can be arbitrarily changed by setting the resistance R ₉ . That is, the lighting state of the discharge lamp La can be changed to any dimming state. Further, when the switch SW ₁ is turned on and off, the voltage V _c4 gradually changes due to the charge / discharge circuit including the capacitors C ₄ , ic ₄ , and R _9.
ref also changes gradually.

In this embodiment, the charging circuit for charging the capacitor C ₄ is composed of a current mirror circuit consisting of transistors Tr ₄ and Tr ₅ , the voltage dividing circuit is composed of resistors R ₃ and R ₄ , and the discharging circuit is composed of resistors. R ₉ , switch SW ₁ , transistor Tr ₁₁ ,
It is composed of a comparator IC ₄ and a resistor R ₁₁ , and the current switching means is composed of a comparator IC ₃ , transistors Tr ₆ , Tr ₉ ,
The resistors R _{6 to} R ₈ and R _{10 are used} , and the output control means is constituted by the Zener diode ZD ₁ and the diodes D _{2 to} D ₄ , the transistors Tr ₂ and Tr ₃ and the resistor R ₅ .

The operation of this embodiment can be summarized as follows.
Until the voltage across the capacitor C ₄ reaches the predetermined voltage E ₃ , a constant voltage (divided voltage by the resistors R ₃ and R ₄ ) is output to the control circuit 2 as the first reference voltage, and the predetermined voltage E _When it reaches ₃ , the voltage (V _c4 − (V _BE3 + V _BE2 + V _D2 )) across the capacitor C ₄ is output as the second reference voltage. Then, the charging voltage of the capacitor C ₄ is higher than the predetermined voltage E ₃ by a predetermined voltage (V _ZD1 +
2V ₃ + V _BE3 ) is reached, the reference voltage V _ref is reached.
_Is limited to a constant voltage (approximately V _ZD1 ).

As described above, in the reference voltage generating circuit 3, according to the charging voltage V _C4 of one capacitor C ₄ , the capacitor C
_{In the} circuit for lighting the discharge lamp La such as a fluorescent lamp by switching the charging current i _c4 of _{No. 4} , the preheating period timer, the soft start from the preheating state to the full lighting state, and the full lighting state and the dimming state. The soft switching and the dimmer switch operation timer can be configured by a circuit using one capacitor C ₄ . Therefore, when the control circuit of the inverter is integrated into an IC, the reference voltage generating circuit 3 needs only one externally attached capacitor, and a circuit suitable for integration into an IC can be configured. Further, the value of the reference voltage Vref is set by setting the capacitor C ₄ , the resistors R ₃ , R ₄ , R ₆ , R ₇ , R ₈ , R ₉ , the reference voltages E ₂ , E ₃ , E ₄ , and the zener diode ZD ₁ . Since the change rate and the change rate thereof can be set arbitrarily, the change in the output of the inverter circuit 1 can be set freely. It is also possible to add a comparator and use the voltage of the capacitor C ₄ to perform the switching operation of the timer operation reference voltage Vref for another function.

[Third Embodiment] FIGS. 6 and 7 show a third embodiment. In addition, IC ₃
~ IC ₇ uses an operational amplifier. When the power is turned on, the reference voltage Vref becomes Vref = Vcc · R ₄ / (R ₃ + R ₄ ). The charging current i _c4 of the capacitor C ₄ is as follows: collector current i _A of transistor Tr ₆ = (Vcc-V _BE7 ) / R ₆ collector current i _B of transistor Tr ₃ = (Vcc-V _BE5 ) / R ₇ transistor Tr ₂ Collector current i _C = (Vcc-V _BE3 ) / R ₈ . When the power is turned on, the output of the comparator IC ₆ is at L level, and the comparator I
Since the output of C ₅ is at L level and the transistor Tr _{8 is} off, the charging power i _c4 of the capacitor C ₄ is i _c4 = i _A
It becomes + i _C.

When the capacitor C ₄ is charged and V _c4 ≧ E ₃ , the output of the comparator IC ₅ changes from the L level to the H level, the transistor Tr ₈ is turned on, and i
_c4 = i _A + i _B + i _c increases, and the rate of increase of V _c4 increases. Here, the operational amplifiers IC ₃ and IC ₄ are voltage follower circuits and have the same input / output voltage. Therefore, the reference voltage E ₃ is Setting the comparator IC ₅ to change from the L level to the H level at the same time as the reference voltage Vref = v
_c4 in relation -V _D2, the reference voltage Vref begins to rise.

When the capacitor C ₄ is further charged and V _C4 ≧ V _ZD1 + 2V _D , a current flows through the zener diode ZD ₁ and the input of the operational amplifier IC ₃ is fixed at V _ZD1 + 2V _D , so Vref = V _ZD1 It is fixed to _{+ 2V D -V D2 = V ZD} + V D. At this time, the comparator IC ₆ changes from the L level to the H level, i _c = 0, the transistor Tr ₃ is turned on, and the transistor Tr ₈ is turned off.
_{Since B} = 0, i _c4 = i _A is reduced to the charging voltage V
The ascending speed of _c4 becomes faster.

When the capacitor C ₄ is further raised and V _c4 ≧ E ₄ , the comparator IC ₇ changes from the L level to the H level, the transistor Tr ₁₀ is turned on, and the switch SW ₁ becomes operable. Become. After that, when the switch SW ₁ is in the off state, Vref = V _ZD + V _D , and when the switch SW ₁ is in the on state, V _c4 determined by i _A and the resistor R _9.
Thus, the reference voltage Vref is determined. When the switch SW ₁ is turned on and off, the reference voltage Vref gradually changes as in the second embodiment. As shown in FIG. 7, each reference voltage Vre
By making the state of f correspond to the preheating period, the soft start period, and the full lighting state, the same control as that of the second embodiment can be performed and the same effect can be obtained.

In the present embodiment, the charging circuit for charging the capacitor C ₄ is composed of a current mirror circuit composed of transistors Tr _{2 to} Tr ₇ , the voltage dividing circuit is composed of resistors R ₃ and R ₄ , and the discharging circuit is composed of The resistor R ₉ , the switch SW ₁ , the transistor Tr ₁₀ , the comparator IC _7, and the resistor R ₁₃ are used, the current switching unit is configured with the comparator IC ₅ , the transistor Tr ₈ , and the resistor R ₇ , and the output control unit is the Zener diode ZD _1. , Diodes D _{2 to} D ₄ , comparator I
It is composed of C ₃ , IC ₄ and resistor R ₅ .

The operation of this embodiment can be summarized as follows.
Until the voltage across the capacitor C ₄ reaches the first predetermined voltage E ₃ , a constant voltage (divided voltage by the resistors R ₃ and R ₄ ) is output to the control circuit 2 as the first reference voltage, and Upon reaching the predetermined voltage _{E 3,} it outputs substantially the voltage across the capacitor _{C 4} and _(V c4 _{-V D2)} as a second reference voltage. Then, when the charging voltage of the capacitor C ₄ reaches the second predetermined voltage (V _ZD1 + 2V _D ) higher than the predetermined voltage E ₃ , the reference voltage V _ref is set to the constant voltage (V _ZD1
+ V _D ).

Example 4 Example 4 is shown in FIGS. 8 and 9. When the power is turned on, the reference voltage Vref output from the reference voltage generation circuit 3
Is Vref = Vcc.R ₄ / (R ₃ + R ₄ ). The charging current i _c4 of the capacitor C ₄ is i _R5 ,
It is determined by i _R6 and i _R7 . IC ₃ ~IC ₅ is a voltage-output comparator. When the power is turned on, both the comparators IC ₃ and IC ₄ output L level, the transistor Tr ₂ is on, the transistor Tr ₃ is off, and i _c4 = i _R5 + i _R6 .

Capacitor _{C 4} is gradually _charged, at a _{V c4} ≧ _{E 2,} the comparator IC ₃ is from the L level to the H level, and turned Torajisuta _{T r4} is, the transistor Tr ₃ is also turned _{on, i c4 = i R5 + i} R6 + i Increased to _R7 ,
The rising speed of V _c4 becomes faster. Here, the reference voltage E
₂ If set to, at the same time the comparator IC ₃ is changed from L level to H level, the reference voltage Vref begins to rise in relation Vref ₌ V c4 _{-V D2.}

When the capacitor C ₄ is further charged and V _c4 ≧ E ₃ , the comparator IC ₄ changes from the L level to the H level, the transistor Tr ₂ turns off, the transistor Tr ₅ turns on, the transistor Tr ₄ turns off, and the transistor Tr ₄ turns off. Since Tr _{3 is} also turned off, it decreases to i _c4 = i _R5 and the rising speed of V _c4 becomes slower. Here, by setting E ₃ = V _ZD1 + V _D2 , when the comparator IC ₄ changes from the L level to the H level, Vref = V _ZD1 and thereafter the reference voltage Vref becomes constant.

When the capacitor C ₄ is further charged and V _c4 ≧ E ₄ , the comparator IC ₅ is changed from the L level to the H level, the tunnel radiance Tr ₆ is turned on, and thereafter the switch SW ₁ becomes operable. When the switch SW ₁ is off, Vref = V _ZD1 , and when the switch SW ₁ is on, Vref determined by the resistors R ₁₄ and i _R5 .
_The reference voltage Vref is determined by _c4 . Switch SW ₁
When turning on and off, the reference voltage V is the same as in the third and fourth embodiments.
_ref gradually changes.

In the case of this embodiment, a charging circuit for charging the capacitor _{C 4,} constituted by Torajisuta Tr _2, Tr ₃ resistors _R 5 to R _9, it constitutes a voltage divider circuit with resistor _R 3, _{R 4,} The discharge circuit is composed of the resistor R ₁₄ , the switch SW ₁ , the transistor Tr ₆ , the comparator IC ₅ and the resistor R ₁₅ , and the current switching means is the comparator IC ₃ , the transistor Tr ₄ , and the resistor R _15.
11 and R ₁₂ , and the output control means is composed of a Zener diode ZD ₁ and a diode D ₂ .

The operation of this embodiment is summarized as follows. Until the voltage across the capacitor C ₄ reaches the first predetermined voltage E ₂ , a constant voltage (divided voltage by the resistors R ₃ and R ₄ ) is output to the control circuit 2 as the first reference voltage, and When the voltage reaches the predetermined voltage E ₂ , the voltage across the capacitor C ₄ (V
_c4 outputs the -V _D2) as a second reference voltage. Then, when the charging voltage of the capacitor C ₄ reaches a predetermined voltage (V _ZD1 ) higher than the predetermined voltage E ₂ , the reference voltage V
Limit _ref to a constant voltage ( _ZD1 ).

[Advantages of the Invention] As described above, the present invention includes a DC power supply, an inverter circuit that converts the voltage of the DC power supply into an AC voltage to supply power to a discharge lamp, and increases when the reference voltage increases, and conversely. In the inverter device including a control circuit that changes the output of the inverter circuit according to the magnitude of the reference voltage so that the reference voltage generation circuit generates the reference voltage, the reference voltage generation circuit is a capacitor. A charging circuit that charges this capacitor, a voltage dividing circuit that divides the power supply voltage of the reference voltage generation circuit to create a constant voltage, a current switching means that switches the charging current of the capacitor by the charging circuit, and the voltage across the capacitor. For preheating the output of the voltage dividing circuit to be preheated by the inverter circuit without lighting the discharge lamp until the voltage reaches the first predetermined voltage. Is output as a first reference voltage of the capacitor, and when the voltage across the capacitor reaches a first predetermined voltage, the current switching means increases the charging current of the capacitor and the gradually increasing voltage across the capacitor is started from the inverter circuit. Is output as a second reference voltage for start-up that generates a sufficient voltage, and when the charging voltage of the capacitor reaches a second predetermined voltage higher than the first predetermined voltage, the inverter circuit keeps lighting the discharge lamp. A means for outputting a third reference voltage for lighting that generates a sufficient voltage to operate, and a series circuit of a resistor and a switch element that are connected in parallel with the above capacitor. When switching, by turning on the above switch element, the voltage across the capacitor is gradually lowered to a predetermined dimming level in the discharge circuit, and all dimming lighting is turned on. When switching to the lamp, by turning off the switch element, the voltage across the capacitor is gradually increased to the second predetermined voltage in the charging circuit, and the fourth soft switching for soft switching the discharge lamp in the inverter circuit. Equipped with a discharge circuit that outputs as a reference voltage, a capacitor that sets the preheat period by varying the reference voltage according to the charging voltage of one capacitor, a soft start capacitor, full lighting and dimming lighting One capacitor can also be used as a function for soft switching with, and the number of capacitors used in the reference voltage generation circuit can be reduced,
A circuit configuration suitable for IC integration can be obtained.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of an embodiment of the present invention, FIG. 2 is an operation explanatory diagram of the same as above, FIG. 3 is a concrete circuit diagram of Embodiment 2 of the same as above, and FIGS. FIG. 6, FIG. 6 is a concrete circuit diagram of the third embodiment of the above, FIG. 7 is an operation explanatory diagram of the same, FIG. 8 is a concrete circuit diagram of the fourth embodiment of the same, FIG. 9 is an operation explanatory diagram of the same, FIG. 10 is a circuit diagram of a conventional example, and FIG. 11 is an operation explanatory diagram of the same. 1 is an inverter circuit, 2 is a control circuit, 3 is a reference voltage generation circuit, 4 is a constant current source, E ₁ is a direct current power source, La is a discharge lamp, C ₁ and C ₄ are capacitors, and R _{1 to} R ₁₁ are resistors. , D
_{1 to} D ₄ are diodes, IC _{1 to} IC ₇ are comparators, SW ₁ is a switch, Tr _{4 to} Tr ₁₁ are transistors, and ZD ₁ is a Zener diode.

Claims (1)

[Claims] 1. A direct current, an inverter circuit for converting the voltage of this direct current into an alternating voltage to supply electric power to a discharge lamp, and a reference voltage that increases when the reference voltage increases and decreases when the reference voltage decreases. In an inverter device including a control circuit that changes the output of the inverter circuit according to the magnitude of the reference voltage and a reference voltage generation circuit that generates the reference voltage, the reference voltage generation circuit includes a capacitor, and a charge for charging the capacitor. A circuit and a voltage dividing circuit that divides the power supply voltage of the reference voltage generating circuit to create a constant voltage,
Before the current switching means for switching the charging current of the capacitor by the charging circuit and the voltage across the capacitor reaches the first predetermined voltage, the output of the voltage dividing circuit is preheated without lighting the discharge lamp by the inverter circuit. First for preheating to be done
Output as the reference voltage of the
When the predetermined voltage is reached, the charging current of the capacitor is increased by the current switching means, and the gradually increasing voltage across the capacitor is output from the inverter circuit as the second reference voltage for starting, which is sufficient for starting. Then, when the charging voltage of the capacitor reaches a second predetermined voltage higher than the first predetermined voltage, a third reference voltage for lighting that generates a voltage sufficient to maintain lighting of the discharge lamp from the inverter circuit Is composed of a series circuit of a switch element and a resistor connected in parallel with the capacitor, and when switching from full lighting to dimming lighting after lighting, by turning on the switching element, the voltage across the capacitor Is gradually reduced to a predetermined dimming level by a discharge circuit, and when switching from dimming lighting to full lighting, the switching element is turned off. And a discharge circuit for gradually increasing the voltage across the capacitor to a second predetermined voltage by the charging circuit and outputting as a fourth reference voltage for soft switching for soft switching the discharge lamp by the inverter circuit. Inverter device characterized by.