JPH05290988A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To prevent generation of a flash at the time of restarting. CONSTITUTION:An HID lamp DL is started by an igniter circuit 2, and the lighting is maintained by an output for which the voltage of a dc power source V1 is converted into a rectangular wave voltage of low frequency by an inverter circuit 1. A high frequency on-duty output from a high frequency generating circuit 5 is changed, and the output supplied to the HID lamp DL is thus adjusted. The lamp voltage of the HID lamp DL is detected by a voltage detection circuit 3. The lighting and non-lighting of the HID lamp DL is judged by a lighting judgement circuit 4. When the lighting of the HID lamp DL is detected, the high frequency on-duty output and the like from the high frequency generating circuit 5 is changed according to the output of the voltage detection circuit 3, and the output supplied to the HID lamp DL is this adjusted.

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 for lighting an HID lamp used as, for example, a vehicle headlight.

[0002]

2. Description of the Related Art FIG. 6 shows a discharge lamp lighting device for lighting a conventional HID lamp. In this discharge lamp lighting device, an inverter circuit 1 that converts a voltage of a DC power supply V ₁ supplied via a power switch S into a low-frequency rectangular wave voltage and supplies the rectangular wave voltage to a HID lamp (hereinafter referred to as a discharge lamp) DL. And the discharge lamp DL
And an igniter circuit 2 for applying a high voltage pulse for starting to the discharge lamp DL, the igniter circuit 2 uses the output of the inverter circuit 1 to create a high voltage pulse for starting, and the output of the inverter circuit 1 The discharge lamp DL is kept to be lit.

The inverter circuit 1 is of a so-called half-bridge type, and smoothing capacitors C _E1 and C _E2 are connected in series at both ends of a series circuit of a DC power supply V ₁ and a power switch S, and a switching element is provided. FET
Q ₁ and Q ₂ are connected in series, a current limiting choke L and a capacitor C ₁ are connected between the connection points of the smoothing capacitors C _E1 and C _E2 and the FETs Q ₁ and Q ₂ , and the discharge lamp DL is Both ends of the capacitor C ₁ are connected in parallel via the igniter circuit 2.

The respective FETs Q ₁ and Q ₂ are shown in FIG.
The drive circuit DR switches with a low-frequency rectangular wave in which the high-frequency rectangular waves shown in (a) and (b) are superimposed. The high frequency rectangular wave is created by comparing the output of the triangular wave oscillator FH with the output adjustment voltage V _X created according to the lamp voltage V _La as described later by the comparator CP ₁ , and the output adjustment voltage V _X is generated. _The lower _X is, the narrower the on-duty, the rectangular wave output can be obtained. Here, the triangular wave oscillator F
The H and the comparator CP ₁ form a high frequency generation circuit 5.

The low frequency rectangular wave is generated by the low frequency oscillator FL ₁ ,
Given by either FL ₂ . For example, if the low frequency oscillator FL ₁ is selected for the reason described below,
The transistor Q ₁ is turned on and off at a high frequency by the output of the comparator CP _{1 while} the low frequency oscillator FL ₁ is at a high level, and is turned off while the low frequency oscillator FL ₁ is at a low level. And transistor Q
_{On the} contrary, ₂ is turned on and off at a high frequency by the output of the comparator CP ₁ while the low frequency oscillator FL ₁ is at the low level, and is turned off while the low frequency oscillator FL ₁ is at the high level.

Here, the low frequency oscillators FL ₁ and FL _{2 are}
And is provided for the following reason. That is, the discharge lamp D
In order to prevent the flicker of light from being felt by the eyes during the lighting of L, the output of the inverter unit 1 during the lighting of the discharge lamp DL is equal to
It is necessary to use a rectangular wave of 00 Hz. Further, when the discharge lamp DL is started by a high-voltage pulse when the power is turned on, if the polarity of the applied voltage is suddenly reversed, it may extinguish, so that a rectangular wave of several Hz to several tens Hz is generated immediately after starting. Is desirable. Therefore, in the case of the above discharge lamp lighting device, a low frequency oscillator FL ₁ that generates a low frequency of several 100 Hz and a low frequency oscillator FL ₂ that generates a low frequency of several 10 Hz are provided.

By the way, as described above, the low frequency oscillator F
L₁, FL₂To switch FETQ₁, Q ₂Drive circuit D
To give to R, the lighting and non-lighting states of the discharge lamp DL and
State of the discharge lamp DL (in a starting state reaching a steady lighting state)
Or not). Therefore, the above discharge
In the case of a lamp lighting device, the lamp voltage V of the discharge lamp DL_LaTo
Lamp voltage detection circuit 3 as state detection means for detection
From the output of the lamp voltage detection circuit 3
A point as a lighting discriminating means for discriminating between a lit state and a non-lit state
A light discriminating circuit 4 is provided.

The lamp voltage detection circuit 3 includes a current limiting choke L.
And capacitor C₁Potential at the connection point of and DC power supply V₁Negative of
The potential difference with the pole is detected. In this case,
Pressure V _LaSmoothing capacitor C_E1, C_E2Partial voltage of (typical
To V₁/ 2) applied voltage is detected, lamp voltage
In the detection circuit 3, this voltage is applied to the resistor R₁, R₂Partial pressure with
C Densa C₃Detection voltage V_DIs getting

In the lighting discrimination circuit 4, the detected voltage V _D is compared with a predetermined voltage by the comparator CP ₂ ,
The lighting state and the non-lighting state are discriminated. The lighting determination circuit 4 outputs a high-level determination signal Va when the discharge lamp DL is turned on and the lamp voltage V _La is lower than the voltage of the DC power supply V ₁ . Low-frequency oscillator F corresponding to the discrimination signal Va output from the lighting discrimination circuit 4
The selection of L ₁ and FL ₂ is performed by the D flip-flop FF ₁ , AND gates AND ₁ and AND _2, OR gate OR ₁ and inverter gate I ₁ . Here, a low frequency generation circuit 7 is configured by these circuits and the low frequency oscillators FL ₁ and FL ₂ . In the low frequency generation circuit 7, the output Q of the D flip-flop FF ₁ is at the low level during the period when the determination signal Va is at the low level (when the discharge lamp DL is not lit), and as shown in FIG. Low frequency oscillator FL ₂
, That is, a low frequency of several tens Hz is output, the determination signal Va becomes a high level (the discharge lamp DL lights up),
When the output of OR gate OR ₁ becomes low level,
The output Q of the D flip-flop FF ₁ becomes low level, and a low frequency of several 100 Hz of the low frequency oscillator FL ₂ is output.

The igniter circuit 2 is similar to that of the inverter circuit 1.
Capacitor C charged by output ₂And this conden
SA C₂Turns on when the charging voltage of the battery reaches a specified voltage
When the voltage responsive element SV and this voltage responsive element SV are on
First, a high voltage pulse is applied to the secondary winding by the current flowing in the primary winding.
It is composed of a pulse transformer PT which is generated. By the way
This discharge lamp lighting device is intended for use in vehicle headlights.
Since it uses a discharge lamp DL,
A quick rise of the bundle is required. Therefore, the above discharge lamp
The high voltage pulse applied to DL is as high as several tens of kV.
The output characteristic of the inverter circuit 1 is also required in FIG.
As shown in (a), even when the discharge lamp DL is steadily lit
Lamp voltage V_LaLamp power is too high during low
Need to be supplied to.

Therefore, in the case of this discharge lamp lighting device,
In order to obtain the output characteristic of the inverter circuit 1, the on-duty of the high frequency generation circuit 5 is made high at the time of starting or restarting. This control is carried out by the transistor Q ₃ which is turned on and off by the output of the D flip-flop FF ₁ and the duty determining circuit 6 including the inverting amplifiers AMP ₁ and AMP ₂ . That is, D flip-flop F
When the duty setting signal V _FL, which is the output of F ₁ , is at the low level, the transistor Q ₃ is off, and at this time, the outputs of the inverting amplifiers AMP ₁ and AMP ₂ are the maximum (that is, the output adjustment voltage V _X). , And the on-duty of the high frequency output of the high frequency generation circuit 5 is maximized to increase the output of the inverter circuit 1 as shown in FIG. Therefore, it is possible to obtain the rapid rising characteristic of the luminous flux at the time of starting and the instantaneous restartability at the time of restarting.

[0012]

However, with the configuration of the above discharge lamp lighting device, when restarted after a short time (for example, a few seconds), as shown in FIG. There was a problem that a flash of light several times as bright as that of This is because the internal pressure of the discharge lamp DL remains high at the time of restarting after a short time, and the lamp voltage V _La immediately after the start.
Is also close to steady. After the start, in the discharge lamp lighting device, the high frequency on-duty of the high frequency generation circuit 5 is in the maximum state until the output of the low frequency oscillator FL ₂ is inverted to the low level, and therefore the inverter circuit 1
Output is in an excessive state as shown in FIG. 9 (b), and a flash light having a brightness several times as high as that in a steady state is generated.

Here, when the discharge lamp DL whose lighting is controlled by the discharge lamp lighting device is used as a headlight of a vehicle, such a flash of light has a psychological effect on a user or an oncoming vehicle. Pleasure etc.) is large and may cause a safety problem. The present invention has been made in view of the above points, and an object of the present invention is to provide a discharge lamp lighting device capable of preventing the generation of flash light at the time of restart.

[0014]

In order to achieve the above object, the present invention provides a DC power supply, an inverter circuit for converting the voltage of the DC power supply into a low frequency rectangular wave voltage and outputting the rectangular wave voltage, and an output of the inverter circuit. HID lamp that lights up with
An igniter circuit that starts by applying a high voltage pulse to the lamp, an output adjusting means that adjusts the output supplied to the HID lamp by varying the switching frequency or the on-duty of the inverter circuit, the lamp voltage of the HID lamp and the lamp. A state detection means for detecting the state of the HID lamp from an electric current and the like, and a lighting discrimination means for detecting lighting or non-lighting of the HID lamp are provided.
When the lighting of the ID lamp is detected, the output adjusting means adjusts the output supplied to the HID lamp according to the output of the state detecting means.

[0015]

The present invention has the above-mentioned configuration,
At the time of restart, an appropriate output according to the state of the HID lamp, for example, the lamp voltage can be supplied from the inverter circuit to the HID lamp, and no flash light is emitted.

[0016]

【Example】

(Embodiment 1) FIGS. 1 and 2 show an embodiment of the present invention.
The components of this embodiment are the same as those described in the conventional circuit of FIG. 6, and the feature of this embodiment is that the duty setting signal V _FL, which has been obtained from the output Q of the D flip-flop FF _{1 in} the past, is used. The point is that the lighting discrimination signal Va of the lighting discrimination circuit 4 is used as it is. That is, in the case of the circuit of FIG. 6, since the D flip-flop FF ₁ had a problem in the period until the output Q was inverted, the discharge lamp DL
And the transistor Q of the duty determining circuit 6
₃ is turned on so that the high frequency generating circuit 5 is supplied with the output adjusting signal V _X according to the lamp voltage V _La .

Even in this case, it is possible to prevent the generation of flashlight while maintaining the rapid rising characteristics of the luminous flux at the time of starting and the instantaneous restartability at the time of restarting. This point will be described in more detail. For example, since the lamp voltage V _La after starting the discharge lamp DL is low at the initial start, the output adjustment signal V _X is high even if the transistor Q ₃ is turned on immediately after the discharge lamp DL is turned on as described above. Therefore, a high-frequency output with a wide on-duty is output from the high-frequency generation circuit 5. That is, an excessive output of the inverter circuit 1 which is almost the same as the conventional one can be obtained,
Thereby, the luminous flux of the discharge lamp DL can be rapidly raised.

On the other hand, at the time of restart, the lamp voltage V _La after starting the discharge lamp DL differs depending on the time elapsed after the lamp is turned off. For example, at the time of restarting after a short time, the internal pressure of the discharge lamp DL remains high, and the lamp voltage V _La immediately after starting is also almost steady. For this reason, the output adjustment signal V _{X at} this time becomes low, and therefore a high-frequency output with an unduly wide on-duty is not output from the high-frequency generation circuit 5. Therefore, the inverter circuit 1 does not supply an excessive output to the discharge lamp DL, which is the same as at the time of initial start, and it is possible to prevent the generation of flash light. Here, since the lamp voltage V _La becomes a voltage according to the lapse of time after the light is turned off, the high frequency generation circuit 5 outputs a high frequency output of an on-duty that is suitable for the time after the light is turned off at the time of restart. Become.

FIG. 2 shows the lamp voltage V _La , the duty of the output of the high frequency generating circuit 5 and the lamp current I _La of this embodiment. The frequency of the low frequency generating circuit 7 is lower than that of the circuit of FIG. It can be seen that the lamp current I _La until it is replaced is kept low. (Embodiment 2) FIGS. 3 and 4 show another embodiment of the present invention. In this embodiment, the lighting characteristics similar to those in the first embodiment are obtained by controlling the output current peak of the inverter circuit 1 according to the state of the discharge lamp DL, that is, the lamp voltage V _La .

Specifically, the current detection circuit 8 is provided between the inverter circuit 1 and the negative electrode of the DC power source V ₁ to detect the output current of the inverter circuit 1. And
A duty control circuit 5'is used instead of the high frequency generation circuit 5 of FIG. This duty control circuit 5'is
The high-frequency oscillator FH, the flip-flop FF ₂ , and the AND gate AND ₅
The on-duty of is adjustable. That is, at the input time point of the high-level signal to the reset terminal R of the flip-flop FF _2, it is possible to adjust the high-level period of the output Q of the flip-flop FF _2. In addition,
When no high level signal is input to the reset terminal R, the output of the high frequency oscillator FH is output as it is.

In order to control the reset of the flip-flop FF ₂ , the duty determining circuit 6 '(however,
A comparator CP ₃ is provided for comparing the output adjustment signal V _X of the transistor Q _{3 (not} provided) with the output voltage V _I of the current detection circuit 8. That is, the output of the duty determining circuit 6'which produces an output according to the detection signal V _D of the lamp voltage detecting circuit 3 and the output of the current detecting circuit 8 are compared, and the output current reaches the output of the duty determining circuit 6 '. At this point, by resetting flip-flop FF ₂ ,
As shown in FIG. 4C, the on-duty of the high frequency output from the duty control circuit 5 ′ is reduced as the lamp voltage decreases (when the discharge lamp DL reaches steady lighting), and the output of the inverter circuit 1 is reduced. Is configured to be small. The left half of FIG. 4 is a waveform showing the operation of the circuit section. In this case, the output of the duty control circuit 5'and the output of the current detection circuit 8 are the peak values of the output current of the inverter circuit 1 so that the required lamp current I _La can be flown according to the lamp voltage V _La. Needless to say to set. By doing so, as in the case of the first embodiment, an excessive lamp current I _La can be made to flow at the time of initial starting to make the rise of the luminous flux abruptly, and an appropriate lamp current I _La can be emitted at the time of restarting. It can be flowed to the electric lamp DL, so that no flash light is generated. Moreover, in the case of the present embodiment, the switching element can be protected by limiting the current peak value by the new circuit section. The insertion position of the current detection circuit 8 may be anywhere as long as it can detect the current of the switching element of the inverter circuit 1.

However, if only this circuit section is used, the discharge lamp D
Since it is not possible to promptly start the discharge lamp DL when L is not lit, in order to prevent this, a transistor that turns on and off with an output obtained by inverting the output of the lighting determination circuit 4 by the inverter gate I _3. Q _X is provided.
That is, the reset terminal of the flip-flop FF ₂ before starting, as the output of the comparator CP ₃ is not inputted, i.e. the comparator CP _3, as the duty determination circuit 6 ', and the current detection circuit 8 does not work, which Thus, a sufficiently high high voltage pulse can be obtained from the igniter circuit 2.

(Embodiment 3) FIG. 5 shows still another embodiment of the present invention. In the case of this embodiment, the igniter circuit 2'which can generate a pulse without being affected by the operation of the inverter circuit 1 is used. The igniter circuit 2 ', turns on transistor Q ₄ at the output of the oscillation circuit OSC, is turned off, storing the pulse energy in the capacitor C ₄ of the secondary output of the flyback transformer FBT, air gap gap
Is generated to generate a high voltage in the secondary winding of the pulse transformer PT. Here, the oscillation circuit OSC stops oscillation by the output of the lighting determination circuit 4 when the discharge lamp DL is lighting, and prevents generation of a high voltage pulse after lighting.

Further, in the case of this embodiment, the duty cycle is determined.
The configuration of the constant circuit 6 "is also characteristic. That is, in the present embodiment,
The duty determining circuit 6 ″ is a transistor in the first embodiment.
Star Q₃Instead of capacitor C_X, Resistance R_XEmpty
Charging / discharging circuit and capacitor C of this charging / discharging circuit_XCharge of
A switch for controlling discharge according to the lighting determination signal Va
S ₁, S₂And inverter gate I_FourIt is composed of.

Now, when the discharge lamp DL is lit, the lighting discrimination signal Va is at a high level, so the switch S ₁ is on and the switch S ₂ is off. Therefore, at this time, the capacitor C _X is charged by the detection signal V _D , and the output adjustment signal V _X is determined according to the detection voltage V _D (ramp voltage V _La ). When the power is cut off and the discharge lamp DL is turned off, the final detection voltage V _D is stored in the capacitor C _X. Then, until the power is turned on next time, the capacitor C _X
Is gradually discharged through the resistor R _X.

Even if the power is subsequently turned on, the lighting discrimination signal Va is at a low level at first, so the switch S ₁ is off and the switch S ₂ is on, that is, the output adjustment signal V _X.
Is the voltage V of the capacitor C _X until the discharge lamp DL is started
Determined according to _C. In this way, by appropriately setting the values of the capacitor C _X and the resistor R _X , the inverter circuit 1 can be operated with an optimum on-duty when the discharge lamp DL is started.

[0027]

As described above, according to the present invention, the DC power supply, the inverter circuit for converting the voltage of the DC power supply into the rectangular wave voltage of the low frequency and outputting the voltage, and the H lighted by the output of the inverter circuit.
An ID lamp, an igniter circuit that starts by applying a high voltage pulse to the HID lamp, an output adjusting means that adjusts the output supplied to the HID lamp by changing the switching frequency or the on-duty of the inverter circuit, and the HID lamp. H from the lamp voltage and lamp current of
A state detection unit that detects the state of the ID lamp and a lighting determination unit that detects lighting and non-lighting of the HID lamp are provided. When the lighting determination unit detects lighting of the HID lamp, the state detection unit outputs the output. Depending on the output adjustment means HI
Since the output supplied to the D lamp is adjusted, an appropriate output according to the state of the HID lamp, for example, the lamp voltage can be supplied from the inverter circuit to the HID lamp at the time of restart, and no flash light is emitted.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a main part operation of the above.

FIG. 3 is a circuit diagram of another embodiment.

FIG. 4 is an explanatory diagram of a main part operation of the above.

5A and 5B are circuit diagrams of still another embodiment,
3 is a specific circuit diagram of a main part.

FIG. 6 is a circuit diagram of a conventional example.

FIG. 7 is an operation waveform diagram of each part of the above.

FIG. 8 is an explanatory diagram of a low frequency output switching operation of the above.

FIG. 9 is an explanatory diagram of a problematic operation of the above.

FIG. 10 is an explanatory diagram of operating characteristics of the above.

[Explanation of symbols]

1 inverter circuit 2 igniter circuit 3 voltage detection circuit 4 lighting determination circuit 5 high frequency generation circuit 5'duty control circuit 6, 6 ', 6 "duty determination circuit 7 low frequency generation circuit 8 current detection circuit V ₁ DC power supply DL HID lamp

Claims (1)

[Claims] 1. A DC power supply, an inverter circuit that converts the voltage of the DC power supply into a low-frequency rectangular wave voltage and outputs the voltage, an HID lamp that is lit by the output of the inverter circuit, and a high-voltage pulse is applied to the HID lamp. The igniter circuit which is started by the above, the output adjusting means for adjusting the output supplied to the HID lamp by changing the switching frequency or the on-duty of the inverter circuit, and the state of the HID lamp from the lamp voltage and the lamp current of the HID lamp. A state detection unit for detecting and a lighting determination unit for detecting lighting or non-lighting of the HID lamp are provided, and the lighting determination unit detects HI.
A discharge lamp lighting device, characterized in that, when the lighting of the D lamp is detected, the output adjusting means adjusts the output supplied to the HID lamp according to the output of the state detecting means.