JPH0613193A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To provide a discharge lamp lighting device by which rise time can be shortened and evenness of light output can be obtained with simple control. CONSTITUTION:A discharge lamp lighting device is provided with a DC converter 11, a PWM regulator 13 to convert output voltage outputted from this DC converter into pulse voltage of prescribed width so as to be outputted and a full bridge driver 14 to impress the pulse voltage on a discharge lamp 15, and is provided with a voltage detecting circuit 16 to detect voltage to be impressed on the discharge lamp 15, an electric current detecting circuit 17 to detect an electric current flowing to the discharge lamp 15, a multiplier 18 to obtain a product of a voltage detecting signal detected by the voltage detecting circuit 16 and an electric current detecting signal detected by the electric current detecting circuit 17 and a comparator 19 to output a comparison signal obtained by comparing an integrated value outputted by this multiplier 18 with a preset reference value. A pulse width modulating means 11 is provided to control the pulse width of the pulse voltage so that this comparison signal becomes zero.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device for lighting a discharge lamp used in a vehicle.

[0002]

2. Description of the Related Art Conventionally, as such a lighting device, FIG.
Is known (see Japanese Patent Laid-Open No. 3-8299).

In FIG. 29, 1 is a DC booster circuit for boosting the DC voltage of the battery 2, 3 is a high frequency booster circuit for converting the output voltage of the DC booster circuit 1 into a sine wave AC voltage, and 4 is power for the discharge lamp 5. A current limiting load and an igniter circuit for supply, 6 is an igniter starting circuit that outputs a starting signal to the current limiting load and igniter circuit 4, and 7 is a control circuit that controls the output voltage of the DC booster circuit 1.

The control circuit 7 includes a voltage calculation unit 7a for detecting the output voltage of the DC booster circuit 1, a current calculation unit 7b for detecting the output current of the DC booster circuit 1, and signals from these calculation units 7a, 7b. The pulse width modulator 7c generates a rectangular pulse having a corresponding duty cycle and sends it to the gate of the FET 1a of the DC booster circuit 1.

In the above lighting device, the lighting switch S
When the lamp is turned on, a starting pulse is first generated by the signal sent from the igniter starting circuit 6 to the current limiting load and the igniter circuit 4, the discharge lamp 5 is triggered, and the control circuit 7 changes the output voltage of the DC booster circuit 1. The control is performed at any time, and finally the discharge lamp 5 is transitioned to the steady state.

[0006]

However, in the above lighting device, the lighting switch S is not provided with the feedback control means for keeping the electric power supplied to the load (discharge lamp 5) constant. It takes a considerable time after the discharge lamp 5 is turned on until the discharge lamp 5 emits a predetermined amount of light. That is, there is a problem that the rising is slow. Further, there is a problem that it is difficult to obtain the flatness of the light output because the feedback control means is not provided.

The present invention has been made in view of the above problems, and an object thereof is to provide a discharge lamp lighting device which can shorten the rise time and can obtain the flatness of the light output. It is in.

[0008]

In order to achieve the above-mentioned object, the present invention comprises a boosting means for boosting a DC input voltage,
In a discharge lamp lighting device comprising pulse generating means for converting an output voltage outputted from the boosting means into a pulse voltage having a predetermined width and outputting the pulse voltage, and a full bridge driver for applying the pulse voltage to a discharge lamp, Voltage detection means for detecting the voltage applied to the discharge lamp, current detection means for detecting the current flowing through the discharge lamp, voltage detection signal detected by the voltage detection means and current detection signal detected by the current detection means Multiplying means for taking the product of, a comparing means for outputting a comparison signal comparing the multiplication value output by the multiplying means with a preset reference value, and a pulse width of the pulse voltage so that the comparison signal becomes zero. And a pulse width modulation means for controlling.

Further, an addition means for adding the voltage detection signal detected by the voltage detection means and the current detection signal detected by the current detection means, and an addition value output by the addition means and a preset reference value are added. Comparison means for outputting the compared comparison signal and pulse width modulation means for controlling the pulse width of the pulse voltage so that the comparison signal becomes zero are provided.

[0010]

According to the present invention, with the above-mentioned structure, the voltage detecting means detects the voltage applied to the discharge lamp, the current detecting means detects the current flowing through the discharge lamp, and the multiplying means detects the voltage detection signal detected by the voltage detecting means. And a current detection signal detected by the current detection means, and the comparison means outputs a comparison signal obtained by comparing the multiplication value output by the multiplication means with a preset reference value,
The pulse width modulation means controls the pulse width of the pulse voltage so that the comparison signal becomes zero.

The addition means adds the voltage detection signal detected by the voltage detection means and the current detection signal detected by the current detection means, and the comparison means calculates the addition value output by the addition means and the preset reference value. The compared comparison signal is output, and the pulse width modulation means controls the pulse width of the pulse voltage so that the comparison signal becomes zero.

[0012]

Embodiments of the discharge lamp lighting device according to the present invention will be described below with reference to the drawings.

[First Embodiment] In FIG. 1, 11 is a DC converter (step-up means) for stepping up a DC voltage of a battery 12, and 13 is a PWM (pulse width modulation) for generating a pulse voltage from the stepped up DC voltage. A regulator 14 converts the pulse voltage into a rectangular wave AC voltage and applies it to a high-intensity discharge lamp (discharge lamp) H.
It is a bridge driver.

Reference numeral 16 is a voltage detection circuit (voltage detection means) for detecting the voltage applied to the lamp 15, and 17 is a current detection circuit (current detection means) for detecting the current flowing through the lamp 15.
Reference numeral 18 is a multiplier (multiplying means) for multiplying the value of the voltage detection signal output by the voltage detection circuit 16 and the value of the current detection signal output by the current detection circuit 17, and 19 is a multiplication signal output by the multiplier 18 in advance. It is a comparator that outputs a comparison signal for comparing with a set reference value (value corresponding to the prescribed power Er of the lamp 15) Vr.

The PWM regulator 13 changes the width of the pulse voltage so that the comparison signal output from the comparator 19 becomes zero. The PWM regulator 13 has a function as a pulse generating means for generating a pulse voltage having a predetermined pulse width and a pulse modulating means for changing the pulse width of the pulse voltage.

Next, the operation of the above embodiment will be described.

When the lighting switch S is turned on, the DC voltage of the battery 12 is boosted by the DC converter 11, and the PWM regulator 13 converts the boosted DC voltage into a pulse voltage of a predetermined width and outputs the pulse voltage. On the other hand, the high voltage trigger circuit (not shown) causes the lamp 15 to start initial lighting. Then, the full bridge driver 14 converts the pulse voltage into a rectangular wave AC voltage and applies it to the lamp 15.

The voltage detection circuit 16 outputs a voltage signal according to the voltage applied to the lamp 15, and the current detection circuit 17 outputs a current signal according to the current flowing through the lamp 15.

Now, assume that the voltage of the voltage signal output by the voltage detection circuit 16 is V1 = βVb and the voltage of the current signal output by the current detection circuit 17 is V2 = αI. However, Vb is lamp 1
5 is a voltage applied to 5, and I is a current flowing through the lamp 15.

The multiplier 18 outputs a multiplication signal which is the product of V1 and V2. If the voltage of this multiplication signal is Vp,
Vp = V1 × V2 = αβVb × I.

The comparator 18 outputs a comparison signal comparing the reference values Vr and Vp, and if Vp is larger than Vr, PWM
The pulse width of the regulator 13 is reduced to reduce the power supplied to the lamp 15. On the contrary, when it is large, the pulse width is increased to increase the power supplied to the lamp 15. Eventually, equilibrium will be achieved with a pulse width of Vp = Vr.

Since a feedback loop based on Vr is formed here, the rated power is always supplied to the lamp 15 by setting Vr to the value of the rated power of the lamp 15. Become.

When the lamp 15 is initially lit, the discharge gas component of the lamp 15 is xenon gas, so the terminal voltage of the lamp 15 is about 25 volts, which is much smaller than the rated voltage (85 volts). In the conventional example, the electric power supplied to the lamp 15 is small. However, the multiplier 18
Since the rated power is supplied to the lamp 15 even in the initial lighting by the feedback loop such as the above, the rated power is supplied to the lamp 15 in a short time after the lighting switch S is turned on. That is, the rise time is short.

[Second Embodiment] FIG. 2 shows a delay circuit 20, 2 between a multiplier 18 and a voltage detection circuit 16 and a current detection circuit 17.
1 is provided. By delaying the response speed by the delay circuits 20 and 21, the electric power supplied to the lamp 15 at the time of initial lighting can be increased, so that the light emission amount of the lamp 15 rapidly increases as shown by the broken line in FIG. ,
The rise time will be even shorter. The graph G1 shown by the solid line shows the case where the delay circuits 20 and 21 are not used.

[Third Embodiment] In FIG. 4, 22 is a non-linear circuit, 23 is a differential amplifier, and a voltage for applying the reference voltage Vc of the comparator 19 to the lamp 15 by the non-linear circuit 22 and the differential amplifier 23. It is designed to be changed according to. That is, Vc is increased when the voltage applied to the lamp 15 is low.

The output voltage of the voltage detection circuit 16 is βVb, and the voltage obtained by nonlinearly processing this output voltage βVb is (βV
b) ^n, and the reference voltage Er of the differential amplifier 23 is Vf + γVi
Then, the voltage Vc output from the differential amplifier 23 is Vc = Vf + γVi− (βVb) ⁿ (1) However, γ, n is an arbitrary real number, and Vi is a voltage for stopping excessive power supply.

Here, the non-linear circuit 22 is composed of three Zener diodes 25 to 27 and three resistors 28 to 30 as shown in FIG. This non-linear circuit 22 is shown in FIG.
When the width characteristic having the saturation characteristic is given as shown in,
The output voltage Vc of the differential amplifier 23 expressed by the equation (1) is
As shown in FIG. 7, as the input voltage (output voltage of the voltage detection circuit 16) input to the non-linear circuit 22 increases near zero, it sharply decreases and becomes a constant value when βVi is exceeded.

Therefore, since the difference between Vc input to the comparator 19 and the voltage Vp output from the multiplier 18 becomes large when the value of βVb is near zero, the PWM regulator 13 has the response characteristic shown in FIG. Will be shown. That is,
At the initial lighting of the lamp 15, the rated power P0 is supplied to the lamp 15.
Since it is possible to supply electric power several times higher than that of the above, the rise time can be extremely shortened. In addition, since the electric power of the lamp 15 becomes constant after the output voltage of the voltage detection circuit 16 is βVi, the flatness of the light output can be obtained.

The chain line shown in FIG. 8 corresponds to that shown in FIG.
Shows the characteristics of the circuit.

[Fourth Embodiment] The discharge lamp lighting device shown in FIG. 9 has a voltage detection signal output from the voltage detection circuit 16 and
The current detection signal output from the current detection circuit 17 is added by the adder 30, and the pulse width of the pulse voltage output from the PWM regulator 13 is changed so that the added signal thus added becomes zero. As a result, the electric power supplied to the lamp 15 is made constant even during the initial lighting. Reference numerals 31 and 32 are amplifiers.

The voltage VA1 = -α output from the amplifier 31
Assuming that Vv is the voltage VA2 = -βVi output from the amplifier 32, the output voltage VA3 of the adder 30 is VA3 = αVv + βVi. However, α and β are the amplification degrees of the amplifiers 31 and 32, V
v and Vi are the voltages of the detection signals output by the voltage detection circuit 16 and the current detection circuit 17.

The PWM regulator 13 controls the conduction time, which is the pulse width of the pulse voltage, and also controls it so that Er = VA3 = αVv + βVi (A) (that is, a detection signal detected by the voltage detection circuit 16). , So that the sum with the detection signal detected by the current detection circuit 17 becomes constant).

The voltage applied to the lamp 15 is the rated voltage Vt.
In this case, the lamp current is also the rated current It so that Vt = αVv. Moreover, when αVv = βVi = 1 / 2Er (B) is set (where Vi is the voltage of the detection signal detected by the current detection circuit 17 when the current flowing through the lamp 15 is It), it is supplied to the lamp 15. Supply power Pt
Pt = Vt × It = αVv × βVi, and the outputs of the amplifiers 31 and 32 are equal and Er / 2.

Now, assuming that the voltage V of the lamp 15 deviates by ± X percent from the rated value Vt, from the equations (A) and (B), Er = αVt (1 ± X) + βVi ... (C) βVi = Er−αVt (1 ± X) = Er {1-1 / 2 (1 ± X)}

[Equation 1] Becomes

The equations (C) and (D) show that the lamp current increases as the lamp voltage decreases, and conversely the lamp current decreases as the lamp voltage increases.

When the electric power Px at this time is calculated,

[Equation 2] Becomes That is, where the lamp voltage is close to the rated value,
As shown in FIG. 10, it is almost constant near the top of the graph. For example, the change in power when Vt changes by 20 percent is 1- (0.2) ² = 0.96, which is only improved by 4 percent. By the way, when it is driven with a constant current, it changes ± 20%.

Further, since the lamp voltage is low at the time of start-up, the current can flow nearly twice as much as the rated value, so that the rising speed is faster than that of the constant current drive.

FIG. 11 is a circuit diagram of the discharge lamp lighting device shown in FIG. In FIG. 11, reference numeral 33 is a full-bridge driver for turning on / off the transistors Q1 to Q4 of the full-bridge circuit 14. By turning on / off the transistors Q1 to Q4, an AC voltage having a frequency of several 10 Hz to several 100 Hz is applied to the lamp 15. It is applied.

The PWM regulator 13 is a transistor Q
It is composed of f and the pulse width modulator 35, and the width of the pulse voltage is determined by the conduction time of the transistor Qf. The conduction time is determined by the pulse width modulator 35. The pulse width modulator 35 compares the addition signal Vc output from the adder 30 with a preset internal reference voltage, and the addition signal Vc When it is lower than the internal reference voltage, the conduction time is lengthened, and conversely, when the addition signal Vc is higher than the internal reference voltage, the conduction time is shortened. That is, the pulse width modulator 35 controls the pulse width of the pulse voltage so that the output voltage Vc of the adder 30 becomes constant, and 36 is a trigger circuit for starting the initial lighting. When it is discharged, the lamp 15 is applied with a trigger voltage to start the discharge.

The full bridge driver 33 and the trigger circuit 36 are omitted in FIGS. 1, 2, 4, 9, and 24 (described later).

Here, the voltage applied to the lamp 15 is V0
(It can be regarded as equivalent to the input voltage of the full bridge circuit 14), the output voltage V1 of the amplifier 31 is V1 = -V0. (R2 / (R1 + R2)). R4 / R3 (2). However, R2 << R3.

On the other hand, assuming that the current flowing through the lamp 15 is Ir, the output voltage V2 of the amplifier 32 is V2 = -Ir.Rr.R6 / R5 (3). However, Rr << R5.

Therefore, the output voltage Vc of the adder 30
Is Vc = {V0.R2.R4 / (R3 (R1 + R2)} + (Ir.Rr.R6 / R5) (4) Further, the formula (4) can be expressed as Vc = hV0 + lIr. , (A) is equivalent to the formula.

If Vc = Er, h = α and l = β, the same format as described above is obtained. The start-up characteristics in such a setting are as shown in FIG. 12, and it is possible to obtain fast start-up characteristics and have stable lighting characteristics. In FIG. 12, φ represents the amount of light emitted from the lamp 15, V0 represents the applied voltage to the lamp 15, and Ir represents the current flowing through the lamp 15.

[Fifth Embodiment] In the discharge lamp lighting device shown in FIG. 13, the resistor R4 of the amplifier 31 is connected in parallel with the capacitor Cv and the resistor Rv connected in series, and the resistor R6 of the amplifier 32 is connected to the capacitor Ci. The resistors Ri are connected in series and are connected in parallel. These capacitors Cv, Ci
And the resistors Rv and Ri make the rise of the starting characteristic shorter. This will be described below.

First, the capacitor C added to the amplifier 32
The action of i and the resistance Ri will be described. Operational amplifier 32
As shown in FIG. 14, the step response of a has a time delay until it reaches a steady value, that is, a value in the case of constant power control, due to the action of the capacitor Ci and the resistor Ri. Due to this time delay, the output voltage Vc of the adder 30 also becomes a value lower than the steady value for a while. As a result, the conduction time of the transistor Qf of the PWM regulator 13 becomes longer, and V0
Work to raise. However, since V0 hardly increases unless the discharge gas component changes, the lamp current Ir rapidly increases near time t0 as shown in FIG.

Since the electric power supplied to the lamp 15 is increased due to the increase of the current, the rising characteristic at the time of starting becomes shorter.

By the way, if the value of Ri is too small, Ir becomes too large and the lamp 15 is destroyed. Therefore, it is preferable that the value is about twice that in the constant power control, that is, the resistance Ri is substantially the same as the resistance R6. Further, it is appropriate that the value of the capacitor Ci is such that the time constant with the resistor Ri is about 2 to 6 seconds.

Only by the action of the capacitor Ci and the resistor Ri,
In the process of decaying the transient current, a dip or hump (hump) in the amount of light emitted from the lamp 15 is generated.
Further, by adding the capacitor Cv and the resistor Rv, it is possible to prevent the occurrence of dips and humps. In this case, the time constants of Cv and Rv are set large.

Only the amplifier 31 has a capacitor Cv and a resistor Rv.
When adding, the step response of the operational amplifier 31a is
Since the time constant is large, it gradually rises as shown in FIG. The startup characteristic in this case is that the rising of the output voltage of the operational amplifier 31a is caused by the capacitor Cv and the resistance R.
As it is delayed by the action of v, as shown in FIG.
Although the applied voltage V0 of 5 rises, the current Ir at the initial stage of lighting continues to flow. Therefore, the electric power supplied to the lamp 15 becomes larger than that in the constant power control until the transient characteristic is attenuated, and the rise from the start (after the start of the rise of the voltage V0; the time t1) becomes faster after the start. .

From the experiment, the value of the resistance Rv is about the same as that of R6, and Cv
It has been found that the value of is preferably such that the time constant is about 10 to 15 seconds.

Combining both FIG. 15 and FIG. 17,
As shown in FIG. 18, it is possible to obtain a characteristic that the rising speed is fast and that dips or humps hardly occur after the rising speed.

[Sixth Embodiment] FIG. 19 shows a configuration in which a resistor R and zener diodes ZD1 and ZD2 are connected instead of the capacitors Cv and Ci and the resistors Rv and Ri shown in FIG. The Zener diodes ZD1 and ZD2 must have a voltage higher than Er / 2.

When the output voltage of the operational amplifier 31a is higher or lower than Er / 2, as shown in FIG. 10, X =
Since there is a deviation from the point of 0, the output power of the PWM regulator 13 decreases from the rated value according to the deviation. Therefore, select ZD1 slightly higher than Er / 2. Then, the applied voltage of the lamp 15 rises and the operational amplifier 31a
20 becomes larger than Er / 2 and shifts from point 1 to point 2 as shown in FIG. 20, the feedback resistance becomes a parallel value of Rf and R4 by the action of ZD1 and resistance Rf. , The gain of the operational amplifier 31a decreases. As a result, the output voltage of the operational amplifier 31a is lowered, and the voltage deviation value (X) from the standard value is substantially reduced. As shown in FIG. 20, the curve connecting points 2 to 3 has a degree of inclination thereof. Becomes slower and the range of constant power control increases. R
Depending on the value of f, it is possible to increase it again like the chain line.

Similarly, if the portion shown by the broken line is increased (a Zener diode and a resistor are added), the effect is further enhanced.
If the same process is performed on the operational amplifier 32a, the effect of the case where the voltage of the lamp 15 is lowered appears, and the constant power control can be performed even for a large deviation.

[Seventh Embodiment] FIG. 21 shows a case where analog switches 41 and 42 are connected instead of the Zener diodes ZD1 and ZD2. In FIG. 21, reference numeral 43 denotes a voltage detection circuit that detects the voltage output by the voltage detection circuit 16, and switch 41 turns on when the voltage detected by the voltage detection circuit 43 is equal to or higher than a predetermined voltage. The switch 42 is turned on when the voltage detected by the voltage detection circuit 43 is equal to or lower than a predetermined voltage. Reference numeral 44 is an inverter.

When the lighting switch S is turned on, the lamp 15 is initially lit by the trigger circuit 36. At this time, the terminal voltage of the lamp 15 is about 25 volts,
Very small compared to the rated voltage (85 volts).

The lamp voltage Vv is monitored by the voltage detection circuit 43. When the lamp voltage Vv is 65 V or less, the analog switch 41 is turned off and the analog switch 42 is turned on so that the output voltage of the operational amplifier 32a becomes small. deep. When the output voltage of the operational amplifier 31a is V1 and the output voltage of the operational amplifier 32a is V2, the output voltage V3 of the adder 30 is V3 = V1 + V2 (10).

The pulse width modulator 35 compares the voltage V3 with the internal reference voltage, and if the voltage V3 is larger,
That is, when the power supplied to the lamp 15 is larger than the reference value, the pulse width is narrowed to reduce the power supplied to the lamp 15. Conversely, when the voltage of V3 is small and the power supplied to the lamp 15 is smaller than the reference value, the pulse width is increased to increase the lamp 1
5, the pulse width becomes constant at the point where Er = V3. That is, equilibrium is achieved with a pulse width that provides constant power.

When the lamp voltage is V0, the output voltage of the operational amplifier 31a is -V1, the lamp current at that time is I1, and the output voltage of the operational amplifier 32a is V2.
The power supply P1 of the lamp 15 is P1 = V0 * I1 (11).

At this time, the output V3 of the adder 30 becomes V3 = V1 + V2 (12)

If the setting is such that V1 = V2 = Er / 2, when the discharge voltage of the lamp 15 gradually increases, V1 also increases, but V2, on the contrary, V2 = Er-V1 (13) It decreases while maintaining the relationship. That is, the lamp current is reduced and the supply power is also reduced. The change in the power at this time is V1 = A1Vv, and V2 = Er-V1 is A2αI1
Can be expressed as follows (where A1 and A2 are the amplification degrees of the operational amplifiers 31a and 32a).

P1 = V1 × I1 = V1 (Er−V1) / A1 · A2 · α = A (ErV1−V1 ² ) = A {− (V1−Er / 2) ² + Er / 4} Since A and Er are constants, FIG.
As shown in, the negative quadratic function is changed. That is, V
Under the condition of 1 = V2 = Er / 2, the power supplied to the lamp 15 peaks at the point of V1 = Er / 2 and is V1 (corresponding to the lamp voltage).
The power will decrease with increasing or decreasing. Also, the change near Er / 2 is gradual.

When P1 is set to 2 to 3 times the rated power and the amplification degree of the circuits of the amplifiers 31 and 32 is switched as shown in FIG.
Rises and P1 approaches the rated power P0, the amplifier 3
Switch the amplification degree of 1 and 32 and change the setting so that the rated voltage and rated power are at the peak points. By doing so, the supplied power is appropriately adjusted according to the voltage / current characteristics (impedance) of the lamp 15.

Specifically, when the lamp voltage Vv is 65 V or less, that is, immediately after the lamp 15 is started to be turned on, the switch 41 is turned off and the switch 42 is turned on to relatively reduce the attenuation of the lamp voltage Vv. Therefore, the lamp current I is largely attenuated. When the lamp voltage is V1, it is set to supply a large amount of electric power. Lamp voltage Vv is 65
When the voltage exceeds the voltage, the switch 41 is turned on and the switch 42 is turned off to make the attenuation of the lamp voltage Vv relatively large, and the attenuation of the lamp current I small to make the rated voltage Vv smaller.
When 0, the rated power P0 is set.

By doing so, the rated power can be supplied almost even if the lamp voltage deviates from the rated value, so that the rise time of the lamp 15 can be considerably shortened. [Eighth Embodiment] In FIG. 24, 51 and 52 are adders 3
It is a non-linear attenuator connected in front of 0.

Now, the trigger circuit (omitted in FIG. 24)
When the lamp 15 is started to be lit by the lamp 15, immediately after lighting, the main component of the discharge gas is xenon.
Voltage is low. Therefore, the voltage V1 of the voltage detection signal detected by the voltage detection circuit 16 is small. Therefore, since the output of the adder 30 becomes equal to the reference voltage Er, the lamp 1
The current I of 5 increases.

In the current detection circuit 17, when the value of the resistor Rr (see FIG. 21) is α, the voltage V2 of the current detection signal output from the current detection circuit 17 is V2 = αI. Since this voltage V2 is attenuated by the attenuator 51, the lamp 1
The current flowing through 5 will further increase.

As shown in FIG. 25, the attenuator 51 has a very small response to a large current. Further, since the lamp voltage Vv is low and the voltage V1 detected by the voltage detection circuit 16 is low at the time of startup, the lamp current becomes a very large value in order to satisfy the equilibrium condition V1 '+ V2' = Er. As shown in FIG. 26, the lamp current at startup is set so that 100 W of electric power is applied to a 35 W lamp.
The applied power has the fastest response when adjusted along the allowable power curve (solid line). In this embodiment, this curve is continuously approximated to accelerate the rise. In addition,
The dotted line in FIG. 26 shows the characteristic curve of the circuit shown in FIG.

When the lamp 15 is heated and the lamp voltage rises, the lamp current decreases to satisfy the equilibrium condition, and the voltage V2 of the current detection signal output from the current detection circuit 17 decreases. . That is, as shown in FIG. 25, a large change in the lamp current (3a part) is followed by a slightly gradual change (2a part), and then a linear change.

The attenuators 51 and 52 are, as shown in FIG.
A non-linear attenuating circuit using the comparators C1 to C4 can be obtained which has better characteristics such as stability and setting accuracy than those using a transistor or a diode.

The attenuator 51 sets the reference voltage Es to Ra, Rb, Rc.
Voltage is divided by, and the divided voltage is comparator C1 ~
It is input to the non-inverting terminal as the reference voltage of C3. The output terminals of the comparators C1 to C3 are connected to the current detection circuit via the resistors R1 to R3 and R. A4 is an operational amplifier. When the output voltage V2 of the current detection circuit 17 is zero, all the comparators C1 to C3 are turned off,
R1 to R3 are not connected.

In the comparator C1, when the output voltage V2 of the current detection circuit 17 rises, the reverse phase input voltage through R and R1 exceeds the divided value of Es, and the comparator C1 is turned on. As a result, the voltage V2 is attenuated by R1 / (R + R1). The point where this attenuation occurs is point 1 in FIG. 26, and Rc may be selected so as to exceed the partial pressure value at this point 1.

Further, when V2 rises, the comparator C2
Is turned on, and the voltage Vb is attenuated by the parallel combined resistance of R1 and R2. This attenuation is {R1R2 / (R1 + R2)} / {R + (R1R2 / (R1 + R2))} = R1R2 / {R (R1 + R2) + R1R2}. The point that receives this attenuation is point 2 in FIG.
Then, at this point 2, Rb may be selected so as to exceed the partial pressure value.

When V2 further rises and the comparator C3 is turned on, the voltage V2 is attenuated by the parallel resistance of the resistors R1, R2 and R3. Then, the point where this attenuation occurs is point 3 in FIG. 26, and Ra may be selected so that the partial pressure value is exceeded at this point 3.

Due to the operation of the attenuator 51, when the lamp voltage is lower than the rated voltage (85 volts), the lamp 15 is quickly started and shifts to the steady state.

When the lamp voltage exceeds the rated voltage, the power applied to the lamp 15 gradually decreases along the quadratic curve. Then, the output voltage V1 of the voltage detection circuit 16 rises, but since this voltage V1 is attenuated by the attenuator 52, the decrease in the current flowing through the lamp 15 is suppressed,
The constant power characteristic is further improved.

That is, when the voltage V2 rises and C4 turns on, V2 becomes (R5R6 / (R5 + R6)) / {R + (R5R6 /
(R5 + R6))}.

When the lamp voltage is above the rated value, the output voltage V2 of the current detection circuit 17 is below the standard value.
The voltage V2 decreases linearly as shown in FIG.
As shown in, the applied power to the lamp gradually decreases after the lamp voltage reaches V0. The attenuator 52 is for improving this.

As shown in FIG. 25, if the attenuation is increased from the point 2 which is slightly higher than the rated voltage 85 V and lower than 102 V, for example, about 92 V, the decrease of the lamp current can be suppressed and the power is restored again. The supply will increase.

As for the standard of the operating voltage of the lamp 15, the upper limit is 102 volts with respect to the standard value of 85 volts, and since the range is narrow, one point of correction is sufficient.

As described above, the operation of the attenuators 51 and 52 makes the start of the lamp 15 extremely fast, and the constant power control is performed over a wide range. Therefore, for a discharge lamp having a large variation in characteristics. In addition, uniform emission characteristics can be obtained, and flatness of light output can be obtained.

Incidentally, the comparator 19 is shown in FIGS. 1, 2, 4, and 24, and the comparator 19 is shown in FIG. 9, FIG. 11, FIG. 13, FIG.
Although not shown in FIG. 1, the pulse width modulator 35 of the PWM regulation 13 also serves as the comparator 19 in general, and is shown in FIGS. 1 to 24 for convenience of description.

[0084]

According to the present invention, the voltage detection means for detecting the voltage applied to the discharge lamp, the current detection means for detecting the current flowing through the discharge lamp, the voltage detection signal detected by the voltage detection means, and the current detection means. Multiplying means for taking the product of the current detection signal detected by, and a comparing means for outputting a comparison signal comparing the multiplication value output by this multiplying means with a preset reference value, so that the comparison signal becomes zero. Pulse width modulation means for controlling the pulse width of the pulse voltage, and addition means for adding a voltage detection signal detected by the voltage detection means and a current detection signal detected by the current detection means. A comparing means for comparing the added value output by the adding means with a preset reference value and outputting a comparison signal; and a pulse width changing control for controlling the pulse width of the pulse voltage so that the comparison signal becomes zero. Since is provided with a means,
The rise time of the discharge lamp can be shortened and the flatness of the light output can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a discharge lamp lighting device according to the present invention,

FIG. 2 is a block diagram showing a configuration of a second embodiment,

FIG. 3 is a graph showing a starting characteristic of a lamp,

FIG. 4 is a block diagram showing a configuration of a third embodiment,

FIG. 5 is a circuit diagram showing a configuration of a non-linear circuit,

FIG. 6 is a graph showing a transfer characteristic of a non-linear circuit,

FIG. 7 is a graph showing characteristics of a differential amplifier,

FIG. 8 is a graph showing response characteristics,

FIG. 9 is a block diagram showing the configuration of a fourth embodiment,

FIG. 10 is a graph showing the relationship between the deviation amount of the lamp voltage and the electric power,

FIG. 11 is a circuit diagram specifically showing the configuration of the fourth embodiment,

FIG. 12 is a graph showing response characteristics,

FIG. 13 is a circuit diagram showing a fifth embodiment.

FIG. 14 is a graph showing a step response of an operational amplifier,

FIG. 15 is a graph showing the response characteristic when only the current at the rising time is increased,

FIG. 16 is a graph showing a step response of an operational amplifier,

FIG. 17 is a graph showing response characteristics when only the rise of voltage is accelerated.

FIG. 18 is a graph showing a response characteristic in which the current at the time of rising is increased and the rising of the voltage is accelerated.

FIG. 19 is a circuit diagram showing a sixth embodiment,

FIG. 20 is a graph showing the relationship between the deviation amount of the lamp voltage and the electric power in the sixth embodiment,

FIG. 21 is a circuit diagram showing a seventh embodiment,

FIG. 22 is a graph showing the relationship between lamp voltage and lamp power,

23 is a graph showing the relationship between the lamp voltage and the lamp power in FIG. 21,

FIG. 24 is a block diagram showing the configuration of an eighth embodiment,

FIG. 25 is a graph showing the relationship between the output of the attenuator and the detection voltage of the voltage detection circuit,

FIG. 26 is a graph showing the relationship between the lamp voltage and the power supplied to the lamp,

FIG. 27 is a circuit diagram showing the configuration of an attenuator,

FIG. 28 is a graph showing the relationship between the output of the attenuator and the detection voltage of the voltage detection circuit,

FIG. 29 is a circuit diagram showing a configuration of a conventional discharge lamp lighting device.

[Explanation of symbols]

 11 DC Converter 13 PWM Regulator 14 Full Bridge Driver 15 High Intensity Discharge Lamp (Discharge Lamp) 16 Voltage Detecting Means 17 Current Detecting Means 18 Multiplier 19 Comparator

Claims (2)

[Claims] 1. A boosting means for boosting a DC input voltage, a pulse generating means for converting an output voltage output from the boosting means into a pulse voltage having a predetermined width and outputting the pulse voltage, and applying the pulse voltage to a discharge lamp. In a discharge lamp lighting device having a full-bridge driver, a voltage detection unit that detects a voltage applied to the discharge lamp, a current detection unit that detects a current flowing in the discharge lamp, and the voltage detection unit detects the voltage. Multiplication means for taking the product of the voltage detection signal and the current detection signal detected by the current detection means, and comparison means for outputting a comparison signal comparing the multiplication value output by this multiplication means with a preset reference value. A discharge lamp lighting device, comprising: a pulse width modulation unit that controls a pulse width of the pulse voltage so that the comparison signal becomes zero. 2. A boosting means for boosting a DC input voltage, a pulse generating means for converting an output voltage output from the boosting means into a pulse voltage having a predetermined width and outputting the pulse voltage, and applying the pulse voltage to a discharge lamp. In a discharge lamp lighting device having a full-bridge driver, a voltage detection unit that detects a voltage applied to the discharge lamp, a current detection unit that detects a current flowing in the discharge lamp, and the voltage detection unit detects the voltage. Adding means for adding the voltage detection signal and the current detection signal detected by the current detecting means, and comparing means for comparing the added value output by the adding means with a preset reference value and outputting a comparison signal. A discharge lamp lighting device, comprising: a pulse width modulation unit that controls a pulse width of the pulse voltage so that the comparison signal becomes zero.