JPH088076A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To secure the safety of a high pressure discharge lamp for use in an automobile headlamp device when the automobile is traveling by providing a power adjusting circuit which keeps the lamp turned on by a minimum amount even when no indicated value of power is inputted from a controller circuit. CONSTITUTION:An inverter circuit 2 converts power supplied from a DC power supply 1 into alternating current and supplies the proper power to a lamp 3 according to a signal input from a power adjusting circuit 5, thereby turning on the lamp 3. A controller circuit 6 sets the power to be supplied to the lamp 3, on the basis of such factors as a detection signal of a lamp state detecting circuit 4 that detects the state of the lamp 3 and time, and the circuit 6 outputs a command value to the circuit 5. The circuit 5 adjusts the switching state of the switching element of the circuit 2 according to signals input from both the circuits 4 and 6, and can turn on the lamp 3 by a minimum amount when there is a signal input at least from the circuit 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device, and more particularly to a lighting device for a vehicle headlamp using a high pressure discharge lamp.

[0002]

2. Description of the Related Art Conventionally, a halogen lamp has been used as a headlight of an automobile. However, the halogen lamp has a disadvantage in that it has a low luminous efficiency with respect to power consumption and has a large amount of heat generation for brightening. I couldn't make it brighter than a certain degree, focusing on sex. Therefore, the use of high-pressure discharge lamps with good luminous efficiency has been studied. However, when the high-pressure discharge lamp is lit with constant power, the brightness is low when the internal pressure is low immediately after the start of discharge, and it is not suitable for use as a headlight in an automobile as it is. Therefore, it is necessary to apply a power larger than the rated power immediately after the start of discharge.

For example, Japanese Laid-Open Patent Publication No. 2-136343 discloses that the lamp current is controlled at the time of starting or restarting the discharge lamp so that the lamp can be sufficiently operated at the initial start or immediately after the start of discharge at restart. Brightening is disclosed. However, there is no disclosure of a method for stopping operation or returning to normal operation when an abnormality such as lighting failure or extinction occurs. Therefore, JP-A-4-342990
The gazette discloses measures against such abnormalities.
Further, in these two publications, the high-pressure discharge lamp used for the headlight is controlled by a fine control of the lamp current or the lamp so that the luminous flux amount is rapidly increased by starting and the stable discharge is maintained. It states that the operation must be performed according to the state.

[0004]

However, it is clarified in Japanese Patent Laid-Open No. 4-342990 that the operation must be changed depending on various conditions, time and the like. In this way, when several operations have to be changed depending on conditions and time, generally, a sequencer or a microcomputer (hereinafter, “microcomputer”) is used.
Although it is possible to use a), etc., a microcomputer etc. creates a program by a human and operates based on it, so malfunctions due to mistakes in the program occur,
Further, since the circuit of the microcomputer is high-density and complicated, there is a possibility that the circuit malfunctions due to noise generated around the device. However, the equipment installed in a car is
Very high reliability is required. For example, no malfunction or malfunction should occur in a noisy environment inside a car or in any environment from very low to very high temperatures. In particular, the headlight device of a vehicle must not go out while running at night.

The present invention has been made in view of the above circumstances, and in a vehicle headlight device using a high pressure discharge lamp, a microcomputer is provided in a control circuit in order to properly turn on the lamp. When used, even when an abnormality occurs in the operation of the control circuit, it continues to be lit as much as possible, and when it is turned off, the relighting operation is immediately performed, and
An object of the present invention is to provide a discharge lamp lighting device that is less likely to malfunction.

[0006]

According to the present invention, in order to solve the above problems, as shown in FIG. 1, an inverter circuit 2 for lighting a discharge lamp 3 with an alternating current and a state of the discharge lamp 3 are detected. State detection circuit 4, a power adjustment circuit 5 that controls the switching element of the inverter circuit 2 to adjust the power applied to the discharge lamp 3, and the power applied to the discharge lamp 3 according to the output of the state detection circuit 4. A controller circuit 6 that outputs an instruction value to the power adjustment circuit 5 is provided, and the power adjustment circuit 5 has a function of continuously maintaining a minimum lighting even when the power instruction value from the controller circuit 6 is not input. It is what

[0007]

With the above-described structure, even if the controller circuit 6 is composed of a microcomputer or the like and an abnormal operation occurs, the power adjustment circuit 5 still operates the controller circuit 6.
Since the minimum lighting can be maintained even if the power instruction value from is not input, light will not be interrupted until it returns to normal operation by the initialization operation,
When used as a vehicle headlight, it is possible to ensure the safety of vehicle traveling.

[0008]

FIG. 1 shows a first embodiment of the present invention. 1
Is a DC power source such as a battery, 2 is an inverter circuit, 3
Is a lamp such as a high pressure discharge lamp, 4 is a lamp state detection circuit,
41 is a lamp voltage detection circuit, 42 is a lamp current detection circuit, 5 is a power adjustment circuit, and 6 is a controller circuit.
The inverter circuit 2 converts the electric power supplied from the DC power supply 1 into AC, and supplies appropriate electric power to the lamp 3 based on a signal input from the power adjustment circuit 5 to light the lamp 3. On the other hand, the controller circuit 6 sets the power supplied to the lamp 3 based on the detection signal of the lamp state detection circuit 4 for detecting the state of the lamp 3 and the factors such as time, and outputs the command value to the power adjustment circuit 5. To do. Then, the power adjustment circuit 5 adjusts the switching state of the switching element of the inverter circuit 2 by the signal input from the lamp state detection circuit 4 and the signal input from the controller circuit 6, and at least from the lamp state detection circuit 4. If the detection signal is input, the lamp 3 can be turned on to the minimum.

Further, in this embodiment, the lamp state detecting circuit 4 is composed of the lamp voltage detecting circuit 41 and the lamp current detecting circuit 42, but it is possible to use either one of them. Two detection signals are input to the controller circuit 6 and the power adjustment circuit 5, but it is clear that only one of them may be input.

With the above configuration, even when a microcomputer or the like is used for the controller circuit 6,
Even if the microcomputer malfunctions and cannot output the detection signal to the power adjustment circuit 5, the power adjustment circuit 5 can perform the minimum lighting operation, so that the lamp 3 is not turned off. . FIG. 2 shows a second embodiment of the present invention. The part related to the lighting operation is the same as that of the first embodiment. In this embodiment, the power adjustment circuit 5 is provided with a reset circuit 51 for generating a signal for initializing the controller circuit 6. The reset signal Rs output from the reset circuit 51 is input to the controller circuit 6, and the controller circuit 6
When the reset signal Rs is input, the initialization operation is performed.

The reset circuit 51 added to the power adjustment circuit 5 operates the controller circuit 6 until the power supply voltage becomes stable so that the lighting operation is not performed when the power supply voltage is unstable immediately after the lighting device is powered on. When there is an abnormality in the signal from the controller circuit 6 and the function of not operating,
That is, when the operation of the controller circuit 6 becomes abnormal, it has two functions of outputting the reset signal Rs to the controller circuit 6 to initialize the controller circuit 6 and restore the normal operation.

With the above configuration, the controller circuit 6 including a microcomputer should be used during the lighting operation.
Even if the operation of the power adjustment circuit 5 becomes abnormal, the function of maintaining the lighting of the power adjustment circuit 5 to a minimum and the function of resetting the reset circuit 51 added to the power adjustment circuit 5 to detect the abnormality and initialize the controller circuit 6 It is possible to maintain the lighting of the lamp 3.

FIG. 3 is a circuit diagram of a third embodiment of the present invention. The inverter circuit 2 converts the electric power of the DC power supply 1 into AC and applies it to the lamp 3 to light the lamp 3. Based on the state of the lamp 3 detected by the lamp voltage detection circuit 41 and the lamp current detection circuit 42, and the command value of the lamp power input from the controller circuit 6, the power adjustment circuit 5 operates as a switching element of the inverter circuit 2. The switching state is adjusted, and predetermined power is applied to the lamp 3 to light it. The drive circuit 7 of the inverter circuit 2 drives the switching element of the inverter circuit 2 based on the inverter signal Sc, which is the reference for polarity reversal input from the controller circuit 6, and inverts the polarity of the AC voltage applied to the lamp 3. .

Normally, the inverter signal that serves as a reference for polarity reversal of the inverter circuit 2 can be generated by an oscillator provided separately from the controller circuit 6, but when the high pressure discharge lamp is used for a vehicle headlight. Since it is necessary to control the complicated lamp power, the controller circuit 6 may use a sequencer or a microcomputer. At that time, since the microcomputer also includes a function such as signal generation, using it helps to reduce the number of parts. The inverter signal monitoring circuit 8 is a circuit that monitors the frequency of the inverter signal Sc input from the controller circuit 6 to the drive circuit 7, and outputs a reset signal Rs when the frequency of the inverter signal Sc deviates from a predetermined frequency, The controller circuit 6 is initialized to return to normal operation. The operation of this embodiment is shown in FIG. In the figure, (a) is the inverter signal Sc input from the controller circuit 6 to the drive circuit 7, (b) is the reset signal Rs, and (c) is the lamp current.

With the above configuration, by monitoring the frequency of the inverter signal Sc, which serves as a reference for the operation of inverting the polarity of the lamp 3, by any chance an abnormality occurs in the operation of the controller circuit 6 and the lamp current It is possible to prevent the polarity frequency from deviating from the specified value, causing the discharge to become unstable due to acoustic resonance phenomena, etc., and to prevent it from disappearing or being visible as flicker. High reliability can be obtained even when used in a lamp.

5 and 6 are circuit diagrams of the fourth embodiment of the present invention. FIG. 5 shows the configuration of the main circuit, and FIG. 6 shows the configuration of the control circuit. S _{1 to} S ₅ are drive signal terminals of the switching elements Q _{1 to} Q ₅ , and Va and Ia are detection signals of the lamp voltage and the lamp current. In this circuit, the switching element Q ₁ is switched by a high frequency to be boosted through the transformer T, and rectified and smoothed by the diode D ₁ and the capacitor C ₁ . The DC voltage is the switching element Q
It is converted into alternating current by the inverter circuit 2 composed of ₂ , Q ₃ , Q ₄ , and Q ₅ , and is applied to the lamp 3 at a low frequency to light the lamp 3. Regarding the electric power applied to the lamp 3, the error amplifier 51 compares the command value of the controller circuit 6 formed by the microcomputer μC and the value of the lamp current detected by the lamp current detection circuit 42, and the output is the highest. The PWM modulator 52 is controlled to be small, and the driver circuit 20 drives the switching element Q ₁ at the frequency of the high frequency oscillator 53. The power applied to the lamp 3 is controlled by the power adjustment circuit 5 including the error amplifier 51, the PWM modulator 52, and the high-frequency oscillator 53 so that the lamp current corresponds to the output of the controller circuit 6. As the command value of the lamp current output by the controller circuit 6, the value detected by the lamp voltage detection circuit 41 for the voltage of the capacitor C ₂ is used as the A / D converter 6
The signal is converted into a digital signal by 1, a lamp current suitable for the lamp voltage is calculated, converted into an analog signal by the D / A converter 62, and input to the error amplifier 51.

On the other hand, the switching elements Q ₂ , Q ₃ ,
The inverter circuit 2 formed by Q ₄ and Q ₅ is
A low-frequency signal is generated by the timer unit 63 built in the microcomputer μC, and a low-frequency drive signal is generated by the low-frequency generation circuit 70 based on this low-frequency signal, and the four switching elements Q ₂ , Q ₃ , Q ₄ and Q ₅ are being driven. At this time, the high potential side switching elements Q ₂ and Q ₄ are driven by the high potential side driver circuits 21 and 22. This high potential side driver circuit 21,
22 requires a power source for driving the elements, and generally, the illustrated diodes D ₂ and D ₃ and capacitors C ₄ and C _{5 are shown.}
Often, a charge pump type power supply circuit is used. This power supply circuit accumulates electric charges in the capacitors C ₄ and C ₅ which are the power supplies of the driver circuits 21 and 22 on the high potential side when the switching elements Q ₃ and Q ₅ on the low potential side are ON, so The switching elements Q ₃ and Q ₅ on the potential side are OFF, and the switching elements Q ₂ and Q ₄ on the high potential side are O.
When N, use the charge of capacitors C ₄ and C ₅ ,
The switching elements Q ₂ and Q ₄ are driven.

The low frequency signal output from the controller circuit 6 is also input to the inverter signal monitoring circuit 8. In this circuit, the capacitor C ₃ is constantly charged with a substantially constant current by the constant current source Is, and the controller circuit 6
The transistor Q ₆ is periodically turned on by the inverter signal input to the low frequency generation circuit 70 from the capacitor C ₃ to discharge the capacitor C ₃ through the transistor Q ₆ . When the voltage of the capacitor C ₃ becomes higher than the reference voltage Vk, the output of the comparator CP is inverted and the controller circuit 6 can be initialized (reset). As a result, when an abnormality occurs in the operation of the controller circuit 6 and the frequency of the inverter signal output from the timer unit 63 decreases, it can be detected and the controller circuit 6 can be initialized to return to a normal state. I can.

In particular, when a charge pump type power supply circuit is used as the power supply for driving the switching elements Q ₂ and Q ₄ of the inverter circuit 2, if the inversion frequency of the inverter circuit 2 becomes lower than usual, Capacitor C ₄ ,
The electric charge accumulated in C ₅ becomes insufficient, the switching elements Q ₂ and Q ₄ cannot be kept ON, and the lamp 3 eventually goes out. In such a case, by configuring as described above, it is possible to initialize the controller circuit 6 and continue to light the lamp 3 before the lamp circuit 3 goes out due to an abnormality in the controller circuit 6. Becomes

FIG. 7 shows the operation of this embodiment. In the figure, (a) is a low-frequency signal output from the timer unit 63, (b) is a drive signal for the switching elements Q ₂ , Q ₃ , (c) is a drive signal for the switching elements Q ₄ , Q ₅ , and (d) ) Is the voltage Vc of the capacitor C ₃ , and (e) is the reset signal Rs. When the low-frequency signal output from the timer unit 63 is generated at regular intervals, the low-frequency signal is divided and the switching elements Q ₂ , Q ₃ and Q ₄ , Q _{5 are} divided.
Drive signals are also generated alternately in a constant cycle. At this time, the capacitor C ₃ is periodically discharged, and its voltage Vc does not exceed the reference voltage Vk. However,
When the interval of the low-frequency signal output from the timer unit 63 becomes longer than that in the normal time, the capacitor C ₃ is not discharged, so that the voltage Vc thereof continues to rise and exceeds the reference voltage Vk. This causes the reset signal R from the comparator CP.
s is generated, and the controller circuit 6 is initialized.

In this embodiment, it is detected that the frequency of the inverter signal is low, but it is also possible to perform the same control by using a circuit which detects that the frequency is high. For example, if a frequency monitoring circuit including a PLL circuit is used as the inverter signal monitoring circuit 8, it is possible to detect both high and low frequency fluctuations. For oscillating the low-frequency signal, even if the low-frequency oscillation circuit 71 is separately provided as shown in FIG. 8 without using the oscillation circuit inside the microcomputer, the same effect can be obtained. it is obvious.

FIG. 9 is a circuit diagram of the fifth embodiment of the present invention. In this circuit, it is assumed that the high pressure discharge lamps 3A and 3B are used as headlights of an automobile, and two lights are simultaneously turned on. In this circuit, the two sets of lighting devices each have a control circuit so that each of the lighting devices can be independently lit, but the low frequency signals are input to the low frequency monitoring circuits 8A and 8B as in the above-described embodiment. Further, the low-frequency signals of the other lighting circuit are also input together. In addition, the reset signal when an abnormality occurs is input to both sets of controller circuits 6A and 6B. With the above configuration, even if an abnormality should occur, the two sets of monitoring circuits 8A and 8B check the circuits, so it is possible to detect the abnormality without any omission and restore the normal state. And reliability is improved.

FIG. 10 is a circuit diagram of a sixth embodiment of the present invention, and FIG. 11 is an operation explanation diagram thereof. In this circuit, a sample and hold circuit (S / H circuit) 9 is inserted into the signal indicating the command value corresponding to the lamp power output from the controller circuit 6, and the signal is input to the power adjustment circuit 5. . The S / H circuit 9 holds the level of the input signal by the output of the watchdog timer circuit (WD circuit) 10. Also, watchdog timer circuit 1
0, like the above-mentioned low frequency monitoring circuit, periodically inputs a signal, outputs an output signal only when the input timing of the signal is deviated, and instructs the S / H circuit 9 to hold the signal. It also serves as a reset signal for the controller circuit 6. In this circuit, the output of the controller circuit 6 is connected to the input of the watchdog timer circuit 10, and the controller circuit 6 outputs a signal periodically as shown in FIG. 11 (a). There is. When a signal is not input to the watchdog timer circuit 10 at the specified cycle T due to an abnormality in the operation of the controller circuit 6, the watchdog timer circuit 10 operates at the signal interval (T + α), and A reset signal as shown in b) is generated. The signal is fixed by the latch circuit 11, and a signal hold command as shown in FIG. 11C is input to the S / H circuit 9, and the level of the signal from the controller circuit 6 is fixed. At the same time, a reset signal as shown in FIG. 11B is input to the controller circuit 6 and the initialization operation is performed. Then, when the operation of the controller circuit 6 is restored, the holding of the latch circuit 11 is released by the latch release signal as shown in FIG. After that, as shown in FIG. 11A, a signal is periodically input to the watchdog timer circuit 10 again, and the power adjustment circuit 5 outputs a command value for power adjustment according to the state of the lamp 3. . With the above configuration, even if the controller circuit 6 performs an abnormal operation, the operation can be returned to the original state and the lamp 3 can be kept lit during that time. Further, in the watchdog timer circuit 10 of this embodiment, the same effect can be obtained not only by monitoring the signal from the controller circuit 6 but also by monitoring the above-mentioned low frequency signal or the like to detect an abnormality. That is clear. Also,
Although the S / H circuit 9 of this embodiment holds an analog signal, the same effect can be obtained by holding a digital signal.

FIG. 12 is a circuit diagram of the seventh embodiment of the present invention, and FIG. 13 is an operation explanation diagram thereof. In the present embodiment, the output of the watchdog timer circuit 10 is input to the controller circuit 6 as a reset signal, and the signal of the power instruction value from the controller circuit 6 is input to the power adjustment circuit 5 via the maximum value limiting circuit 12. Therefore, when the watchdog timer circuit 10 operates, the maximum value of the power instruction value is limited. As a result, when an abnormality occurs in the operation of the controller circuit 6 and the watchdog timer circuit 10 operates, the instruction value of electric power is limited, so an excessively large instruction value is erroneously output and the lamp 3 is erroneously output. It is possible to prevent the lamp 3 from being damaged by applying excessive power. FIG. 13 shows the output characteristic of the controller circuit 6, in which the indicated value of the lamp current Ia is set according to the lamp voltage Va. In the figure, Im is the maximum value limited by the maximum value limiting circuit 12. Further, the maximum value limiting circuit 12 can also be used as a circuit for preventing excessive electric power from being applied to the lamp causing the slow leak.

FIG. 14 is a circuit diagram of an eighth embodiment of the present invention, and FIG. 15 is an operation explanation diagram thereof. In the present embodiment, the maximum value circuit 13 is inserted in the signal of the instruction value from the controller circuit 6 and is compared with the output of the lighting maintaining circuit 14, and the higher signal is input to the power adjustment circuit 5. ing. The lighting maintaining circuit 14 originally outputs an instruction value lower than the instruction value output by the controller circuit 6, and accuracy is not particularly required. FIG. 15 shows the output characteristic of the controller circuit 6, in which the indicated value of the lamp current Ia is set according to the lamp voltage Va. In the figure, the characteristic indicated by a broken line is an output for maintaining lighting output from the lighting maintaining circuit 14. As a result, even if the operation of the controller circuit 6 becomes abnormal and an instruction value of electric power that turns off the lamp 3 is output, the lighting maintaining circuit 1
By the action of 4, the lamp 3 can be kept lit without being extinguished. Also at that time, the controller circuit 6 is initialized immediately by the action of the watchdog timer circuit 10 when an abnormality occurs, and the lighting operation is continuously maintained. With the above configuration, the lamp 3 continues to light up without being extinguished, which is useful for improving reliability. Further, by combining this embodiment with the seventh embodiment described above, even if an abnormality occurs in the controller circuit 6, it is possible to properly turn on the lamp 3 without applying a power largely deviated from the normal power. Can be maintained at

FIG. 16 is a circuit diagram of the ninth embodiment.
7 is a diagram for explaining the operation. The power adjusting circuit 5 and the inverter circuit 2 are the same as those in the above-mentioned embodiments. In this embodiment, the controller circuit 6 is provided with a D / A converter 64 and an A / D converter 65, and a capacitor 66 is connected to its analog terminal. The capacitor 66 is always charged with a voltage having a value corresponding to the power instruction value or a state of the lamp 3, for example, a voltage having a value corresponding to the lamp voltage Va, and an abnormality occurs in the operation of the controller circuit 6,
When reset, the voltage of the capacitor 66 is read according to the flow of FIG. 17, and lighting is continued so as not to give a sudden change in power to the lamp 3 in the lighting state. With the above-described configuration, even if the operation of the controller circuit 6 is abnormal, even if the lamp 3 continues to be turned on, the lamp 3 is prevented from abruptly changing in electric power, and the light being turned on is not changed. The state of can be kept as constant as possible.

By the way, in the discharge lamp lighting device, as shown in FIG. 18, it is formed of two circuit blocks: a power circuit through which a large current flows and a control circuit 16 surrounded by a broken line for controlling the power circuit. It is common that Particularly, in a lighting circuit for a discharge lamp such as used for a vehicle headlight, a large amount of light flux needs to be rapidly increased at the time of starting, so a large current flows through the circuit. Therefore, since the switching element has a large loss, it is necessary to dissipate the heat, and when mounting the element on a printed circuit board, it is widely arranged to arrange it in the peripheral part of the board and make it contact with the case to enhance the heat dissipation effect. There is. Further, in the control circuit 16 that drives the switching element and detects the state of the power circuit, the one that is as close as possible to the switching element prevents the superposition of noise and is useful for stable operation of the circuit. Therefore, conventionally, as shown in FIG. 19, the switching elements Q _{1 to} Q ₅ are arranged in the peripheral portion of the substrate 17, the control circuit 16 is arranged in the vicinity thereof, and the capacitors C ₁ and C ₂ and the transformer T are located far away. Had been placed. However, flow is large current is not only the switching element Q ₁ to Q _5, are those through which a current larger in such a transformer T and a capacitor C _1, C _2, current flows through the power circuit in a loop. Therefore, as shown in FIG. 19, when the control circuit 16 is arranged so as to be closest to the switching elements Q _{1 to} Q _5, etc., the circuit current flows in a loop as described above, and the control circuit 16 enters the loop. Will be placed.
In this way, when a large loop current flows, a large electromagnetic noise is generated there. Therefore, when the circuit is operated in such an arrangement, the control circuit 16 having a low signal level is greatly affected and the circuit cannot operate normally.

Therefore, as shown in FIG. 20, the power circuit
And the control circuit 16 is preferably arranged. First,
Touching element Q₁~ Q_FiveGenerates heat as described above,
It is arranged in the peripheral portion of the substrate 17 for heat dissipation. Soshi
, Transformer T, capacitor C ₁, C₂Switch on
Element Q₁~ Q_FivePlaced in the immediate vicinity of the control circuit 16
Is placed on the outside. In other words, switching element
Q₁~ Q_Five, Transformer T, capacitor C₁, C₂Etc
The control circuit 16 is arranged outside the formed power area.
It is. By arranging in this way, the control circuit
16 is outside the current loop and occurs inside the current loop
It is less susceptible to electromagnetic noise. that's all
By configuring as described above, the operation of the control circuit 16 can be operated at a low level.
It is possible to improve the qualitativeness and improve the reliability of the discharge lamp lighting device.
Help on. In addition, as shown in FIG. 21, the control circuit is
The same applies when it is configured by the plug section 16a and the microcomputer 16b.
In this case, the microcomputer 16b is particularly vulnerable to noise.
So, as shown in Fig. 21, place it farthest from the power circuit.
By doing so, more stable operation becomes possible.

FIG. 22 shows the arrangement of another embodiment,
In order to make the board 17 small, the switching element Q₁~
Q_FiveShows the case where is not lined up on one side of the board 17.
The point where the control circuit is placed outside the power area is
Similar to the previous embodiment. Especially in this case, the analog section
16a and microcomputer 16b constitute a control circuit
Occasionally, the microcomputer 16b, which is vulnerable to noise, operates at high frequency.
Switching element Q ₁It is placed away from. This
Stability of control circuit operation by configuring
Is more enhanced.

[0030]

According to the invention of claims 1 to 10, even if an abnormality should occur in the controller circuit of the discharge lamp lighting device, it is possible to continue the operation while maintaining the lighting of the lamp. When used as a headlight of an automobile, there is an effect that reliability can be particularly improved and that the vehicle can contribute to safe driving. Further, according to the invention of claim 11, the control circuit can be arranged in an environment with less noise, and stable operation can be realized.

[Brief description of drawings]

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

FIG. 2 is a circuit diagram of a second embodiment of the present invention.

FIG. 3 is a circuit diagram of a third embodiment of the present invention.

FIG. 4 is an operation waveform diagram of the third embodiment of the present invention.

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

FIG. 6 is a circuit diagram of a control circuit unit according to a fourth embodiment of the present invention.

FIG. 7 is an operation waveform diagram of the fourth embodiment of the present invention.

FIG. 8 is a circuit diagram of a fifth embodiment of the present invention.

FIG. 9 is a circuit diagram of a sixth embodiment of the present invention.

FIG. 10 is a circuit diagram of a seventh embodiment of the present invention.

FIG. 11 is an operation waveform diagram of the seventh embodiment of the present invention.

FIG. 12 is a circuit diagram of an eighth embodiment of the present invention.

FIG. 13 is an operation explanatory diagram of the eighth embodiment of the present invention.

FIG. 14 is a circuit diagram of a ninth embodiment of the present invention.

FIG. 15 is an operation explanatory diagram of the ninth embodiment of the present invention.

FIG. 16 is a circuit diagram of a tenth embodiment of the present invention.

FIG. 17 is an operation explanatory diagram of the tenth embodiment of the present invention.

FIG. 18 is a circuit diagram of a conventional general discharge lamp lighting device.

FIG. 19 is a plan view showing a mounted state of a conventional general discharge lamp lighting device.

FIG. 20 is a plan view showing a mounting state of an eleventh embodiment of the present invention.

FIG. 21 is a plan view showing a mounted state of a twelfth embodiment of the present invention.

FIG. 22 is a plan view showing a mounting state of a thirteenth embodiment of the present invention.

[Explanation of symbols]

 1 DC power supply 2 Inverter circuit 3 High-pressure discharge lamp 4 State detection circuit 5 Power adjustment circuit 6 Controller circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaharu Kitado 1048, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works Co., Ltd. (72) Kuji Ito, 1048, Kadoma, Kadoma City, Osaka Matsushita Electric Works, Ltd. (72) ) Inventor ▲ Matsu ▼ Moto Tatsuhiko 1048, Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works, Ltd.

Claims (11)

[Claims] 1. An inverter circuit for lighting a discharge lamp by alternating current, a state detection circuit for detecting a state of the discharge lamp, and a power adjustment circuit for controlling a switching element of the inverter circuit to adjust electric power applied to the discharge lamp. Equipped with a controller circuit that outputs an instruction value of the power applied to the discharge lamp to the power adjustment circuit according to the output of the state detection circuit, and the power adjustment circuit is a minimum even when the power instruction value from the controller circuit is not input. A discharge lamp lighting device having a function of continuously maintaining lighting. 2. A reset circuit for initializing the controller circuit when the operation of the controller circuit is determined to be abnormal or when the operation of the controller circuit is disturbed, is added to the power adjustment circuit. The discharge lamp lighting device according to claim 1. 3. The controller circuit is constituted by a microcomputer.
Or the discharge lamp lighting device according to 2. 4. An inverter circuit for lighting a discharge lamp by alternating current, an oscillating circuit for generating a signal as a reference of a frequency of polarity reversal of the inverter circuit, a state detection circuit for detecting a state of the discharge lamp, and a switching of the inverter circuit A power adjustment circuit that controls the elements to adjust the power applied to the discharge lamp, a controller circuit that outputs an instruction value of the power applied to the discharge lamp to the power adjustment circuit according to the output of the state detection circuit, and an oscillator circuit A discharge lamp lighting device, comprising: a monitoring circuit that monitors whether or not the frequency of the output signal is within a predetermined range, and if the frequency is outside the predetermined range, performs an initialization operation of returning to a normal frequency. 5. The switching element on the high potential side in the inverter circuit is configured to be supplied with power required for normal driving by inverting the polarity of output power. The discharge lamp lighting device described. 6. An inverter circuit for lighting the discharge lamp by alternating current, a state detection circuit for detecting the state of the discharge lamp, and a power adjustment circuit for controlling a switching element of the inverter circuit to adjust the electric power applied to the discharge lamp. A controller circuit that outputs an instruction value of the power applied to the discharge lamp to the power adjustment circuit according to the output of the state detection circuit, a hold circuit that can fix the signal level of the instruction value of the controller circuit, and at least the controller circuit. A discharge lamp lighting device, comprising means for operating a hold circuit when not operating. 7. A hold circuit fixes a signal level of an instruction value immediately before the abnormality is detected by monitoring whether or not the operation of the controller circuit is normal and detecting an abnormality in the operation of the controller circuit. 7. The discharge lamp lighting device according to claim 6, further comprising a monitoring circuit for inputting the power to the power adjusting circuit. 8. An inverter circuit for lighting the discharge lamp by alternating current, a state detection circuit for detecting a state of the discharge lamp, and a power adjustment circuit for controlling a switching element of the inverter circuit to adjust electric power applied to the discharge lamp. Controller circuit that outputs an instruction value of the power applied to the discharge lamp to the power adjustment circuit according to the output of the state detection circuit, a monitoring circuit that monitors whether the operation of the controller circuit is normal, and the operation of the controller circuit A discharge lamp lighting device, comprising: a maximum value limiting circuit that limits a maximum value of an instruction value input from the controller circuit to the power adjusting circuit when an abnormality is detected in the. 9. An inverter circuit for alternating-currently lighting a discharge lamp, a state detection circuit for detecting a state of the discharge lamp, a power adjustment circuit for controlling a switching element of the inverter circuit to adjust power applied to the discharge lamp, A controller circuit that outputs an instruction value of the power applied to the discharge lamp to the power adjustment circuit according to the output of the state detection circuit, and a lighting maintenance that constantly outputs an instruction value that is smaller than the instruction value output from the controller circuit during normal operation. A discharge lamp lighting device comprising: a circuit; and a maximum value circuit that compares an output of a controller circuit and an output of a lighting maintaining circuit and gives a larger instruction value to a power adjustment circuit. 10. An analog storage circuit for constantly storing a value corresponding to a state of a discharge lamp as a charge amount is added to a controller circuit, and when the controller circuit is initialized, the contents of the analog storage circuit are read out and the value thereof is read. The discharge lamp lighting device according to claim 4, wherein the lighting operation is continued based on the above. 11. A discharge lamp lighting device comprising at least one switching element and a control circuit for detecting the state of a discharge lamp and controlling the switching element, wherein the switching element and other parts are mounted on a printed circuit board. A discharge lamp lighting device, comprising: a component forming a loop through which a current switched by a switching element and the control circuit are arranged outside an area where the switching element is arranged.