JP3291020B2 - Discharge lamp lighting device - Google Patents

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 (high pressure discharge lamp), and more particularly to a vehicle lighting device.
The present invention relates to a discharge lamp lighting device for lighting an HID lamp used for a headlight .

[0002]

2. Description of the Related Art FIG. 8 shows a discharge lamp lighting device for an HID lamp (hereinafter simply referred to as a discharge lamp). In the discharge lamp lighting device, the electric charge of the DC power supply V ₁ of the two ends to the power supply switch S to over and connected smoothing capacitor C _2, and converted into an AC voltage using an inverter circuit A, the output of the inverter circuit A To turn on the discharge lamp DL.

The inverter circuit A includes switching elements (FETs) Q ₁ and Q _{1 at} both ends of a smoothing capacitor C _2.
3 and to connect the series circuit of the switching element Q _2, Q _4, the connection point of the switching elements Q _1, Q ₃ of the series circuit of each and between the connection point of the switching element Q _2, Q _4, the current limiting coil L Discharge lamp DL is connected via
A so-called full-bridge configuration in which a capacitor C ₁ in parallel. The respective switching elements Q _{1 to} Q
₄ is a so-called separately-excited type which is switched by the drive circuit DR.

The switching control of the switching elements Q _{1 to} Q ₄ by the respective drive circuits DR is performed according to the outputs of the low frequency oscillator G ₁ and the high frequency oscillator G ₂ . Low-frequency oscillator G ₁ generates a square wave signal f _L of several 100Hz shown in FIG. 9 (b), the square wave signal f _L is the duty becomes 50%. The high-frequency oscillator G ₂ is shown in FIG.
A square wave signal f _H of about several tens kHz shown in FIG. However, in FIG. 9A, the horizontal axis is widened to clearly show the waveform of the rectangular wave signal f _L , and the frequency is actually much higher than that of the rectangular wave signal f _{H in} FIG. 9B. .

[0005] The output of the low frequency oscillator G ₁ and the high-frequency oscillator G ₂ is inputted to the AND gates the AND _1, the drive circuit DR to output took and in the AND gate the AND ₁ corresponds to the switching element Q _1, Q ₄ Given to. The output of the output and the high-frequency oscillator G ₂ obtained by inverting the output of the low frequency oscillator G ₁ by the inverter gate INV ₁ is input to an AND gate the AND _2, the AND gates A
The output obtained by ANDing at ND ₂ is the switching element Q ₂ ,
It is given to the drive circuit DR corresponding to Q _3. Here, the output waveforms of the respective AND gates AND ₁ and AND ₂ are shown in FIG.
The waveforms shown in (c) and (d) are obtained.

The operation of the discharge lamp lighting device will be described. Electric
When the power switch S is turned on, the switch of the inverter circuit A is switched on.
Ching element Q₁, Q_FourAnd switching element Q_Two, Q_Three
And a low-frequency oscillator G₁ON or OFF depending on the output of
Is That is, the low-frequency oscillator G₁Square wave signal f_L
Is high level, the switching element Q₁, Q
_FourIs a high-frequency oscillator G_TwoSquare wave signal f_HON according to,
Is turned off and the low-frequency oscillator G₁Square wave signal f_LBut Loule
The switching element Q_Two, Q _ThreeIs high lap
Wave oscillator G_TwoSquare wave signal f_HTurned on and off according to
You. Thus, the switching element Q₁~ Q_FourIs a switch
Current limiting coil L and capacitor C
₁And a discharge lamp DL is applied with a rectangular wave voltage.
As a result, the discharge lamp DL is lit in a so-called rectangular wave. here,
The current limiting coil L works as a high frequency current limiting element,
Densa C₁Works to bypass high frequency components.
This gives a rectangular wave with less high frequency components to the discharge lamp DL
It is so.

[0007]

The above-described discharge lamp lighting device
With the discharge lamp DL turned on, the power switch S is turned off.
Then, the discharge lamp DL is turned on as shown in FIG.
The light turns off within a few milliseconds or less after S is turned off. Here, the power switch
Time until the discharge lamp DL goes out after the switch S is turned off
Is the capacitor C_TwoThis is caused by the charge of Ma
This capacitor C _TwoCharge of the inverter circuit A
Operation voltage of the control circuit
Stops, the discharge of the discharge lamp DL is stopped and instantaneously fired.
The light amount becomes 0.

By the way, since the incandescent lamp emits heat, a so-called afterglow phenomenon that continues to emit light as shown in FIG. 11 occurs until the filament temperature decreases to a constant value even when the power is turned off. Generally, human eye response is 10ms
Since it is performed in the order of ec, if the lamp is turned off instantaneously as in the discharge lamp lighting device described above, a reaction with a large differential value is given to the human eye. When such a discharge lamp lighting device is used to turn on a vehicle headlight or the like, a sudden visual change is given to a driver or an oncoming vehicle, and a psychological burden is added. Doing so can cause safety problems. In this regard, when the light emission amount changes as in the case of an incandescent electrode or the like, the light gradually darkens, and the above-described problem does not occur.

[0009] The present invention has been made in view of the above points, and an object of the present invention is to make headlights rapidly
Psychological impact on the driver and oncoming vehicle due to turning off
An object of the present invention is to provide a discharge lamp lighting device capable of reducing a load and improving safety .

[0010]

According to the first aspect of the present invention, a DC power supply, an inverter circuit for converting the voltage of the DC power supply to an AC voltage, and a lighting circuit provided by an output of the inverter circuit. And headlights for vehicles.
A lamp used is that release, and off detecting means for the power switch detects that it has been turned off, the discharge lamp the on-duty or the switching frequency of the switching elements of the inverter circuit within a predetermined time from the off time of the power switch variable to Dimming control means for gradually decreasing the amount of light emission until the light is almost turned off, and an inverter for maintaining lighting of the discharge lamp at least for a certain period of time after the power switch is turned off
A power supply unit for supplying power to the circuit and the dimming control unit .

According to the second aspect of the present invention, there is provided a DC power supply, and an inverter circuit for converting a voltage of the DC power supply into an AC voltage.
Lighted by the output of this inverter circuit, the head for the vehicle
A lamp release that used in the light, and a smoothing capacitor for supplying electric charge to the OFF state of the power switch as a power supply, a voltage detection means voltage across the smoothing capacitor is detected to be decreased below a predetermined voltage, the smoothing capacitor Dimming control means for varying the on-duty or switching frequency of the switching element of the inverter circuit within a certain time from the point in time when the voltage between both ends falls below a predetermined voltage, and gradually decreasing the light emission amount of the discharge lamp until the light is almost turned off. And

[0012]

According to the first aspect of the present invention, the discharge lamp is kept lit even after the power switch is turned off, and the light emission amount of the discharge lamp is gradually reduced until the lamp is turned off. is, in substantially the same state as the afterglow characteristics of an incandescent light bulb, this gradually darken the discharge lamp when off the power switch
The luck associated with suddenly turning off the headlights
Reduces the psychological load on divers and oncoming vehicles and increases safety
Improve .

According to a second aspect of the present invention, by using the charge of the smoothing capacitor as a power source, the respective sections at the subsequent stage of the power switch are operated, and the discharge lamp is turned on even after the power switch is turned off. By keeping it in a possible state, and gradually reducing the amount of light emitted from the discharge lamp until it goes out, in a state almost similar to the afterglow characteristics of the incandescent lamp, the discharge lamp is gradually darkened when the power switch is turned off . Hedra
For drivers and oncoming vehicles due to sudden turn off of lights
Reduce the psychological load and improve safety .

[0014]

【Example】

(Embodiment 1) FIGS. 1 to 3 show an embodiment of the present invention.
The discharge lamp lighting device of the present embodiment is based on the circuit of FIG. 8, and the configuration of the circuit portion other than that surrounded by a broken line frame in FIG. 8 is different. FIG. 1 shows a circuit configuration of the discharge lamp lighting device of the present embodiment.
And a circuit portion (hereinafter, referred to as a frame portion shown in FIG.
(Referred to as the main circuit) is indicated by X.

In the discharge lamp lighting device of this embodiment, the main circuit X is continuously supplied with the power from the DC power supply V ₁ even after the power switch S is turned off. By gradually lowering the output, the discharge lamp DL is gradually darkened and turned off after the power switch S is turned off. Here, in order to continue the supply of power from the DC power supply V ₁ after the main circuit X off the power switch S, are using a relay Ry ₁ comprising a contact r ₁ normally open. That is, connected in parallel to the contact r ₁ to the power switch S, a predetermined time after off of the power switch S is be to close the contact r _1, so as to continue the supply of power to the main circuit X It is. Note that a control power supply V _CC, which is a power supply of a control circuit unit that controls switching of the switching elements Q _{1 to} Q ₄ of the inverter circuit, is taken from a point via a contact r ₁ .

[0016] Then, in order to reduce gradually the output of inverter circuit provided to the discharge lamp DL to the duration of the power supply, so as to perform so-called PMW control gradually decreases the on-duty of the rectangular wave signal f _H It is.
Specifically, on the power switch S, OFF, switching element (transistor) and Q _X, inverter gate INV
_2, is detected by the circuit consisting of the diode D _1. That is,
When the power switch S is turned off, the potential becomes 0 in the power switch S and diode D ₁ and the connection point, by inverting the potential at the inverter gate INV _2, it is constituted to turn on the switching element Q _X. Here, the diode D ₁ is an inverter gate INV by closing of the contact r ₁
It is provided to prevent the input potential of the _second from changing.

The switching element Q_XWhen on
Is a high-frequency oscillator G_Two’, Comparator CP₁, Conde
Sensor C_ThreeAnd resistance R₁~ R_ThreeCircuit consisting of
No. f _LGradually reduce the on-duty of the inverter
Gradually lower the output of the circuit. Where the high frequency oscillator
G_Two′ Is a triangular wave signal f shown in FIG._SAlso cause
And the comparator CP₁Is the high-frequency oscillator G
_Two’Triangular wave signal f_SAnd capacitor C_ThreeVoltage V_X
By comparing with the capacitor C_ThreeVoltage V
_XSquare wave signal f whose on-duty changes according to_HTo
Output.

[0018] Now, if the power switch S is turned on, the switch element Q _X is the off, the capacitor C
₃ is charged to a constant voltage determined by the divided voltage of the resistors R ₁ to R _3, the on-duty of the output f _H of the comparator CP ₁ in this case is constant. When the power switch S is turned off, the switch element Q _X is turned on, charges of the capacitor C ₃ is discharged through the resistor R ₂ and a switch element Q _X a resistor R _3, the voltage across the capacitor C ₃ V _X gradually decreases. Accordingly, as shown in FIG. 2 (c) with a decrease in the voltage across V _X of the capacitor C ₃ shown in FIG. 3 (b), on-duty of the rectangular wave signal f _H as the output of the comparator CP ₁ is gradually Become smaller. With such on-duty is reduced, the on period of the switching element Q ₁ to Q ₄ of the inverter circuit becomes short, output provided to the discharge lamp DL is lowered, the discharge lamp DL
Gradually darkens and eventually goes out. And the power supply
When the switch S is turned off, the discharge lamp DL is gradually darkened.
The headlights suddenly turn off,
Reduces the psychological burden on oncoming vehicles and improves safety
Can be made.

By the way, the relay Ry₁Drive control
Is the capacitor C_ThreeVoltage V _XThis is performed using
That is, this capacitor C_ThreeVoltage V_XAnd reference voltage
V_R1And the comparator CP_TwoAnd the reference voltage V_R1To
Capacitor C_ThreeVoltage V_XRelay R during the period when
y₁To drive the contact r₁Is closed. Therefore,
In the case of the embodiment, the power switch S is turned on and the
Sensor C_ThreeVoltage V_XIs the reference voltage V_R1When exceeded
At the contact r₁Is closed and the capacitor C_ThreeVoltage V_X
Is the reference voltage V_R1Until it falls below
You. However, when the power switch S is turned off,
Sa C_ThreeVoltage V_XIs the reference voltage V_R1Until the point below
Contact r₁May be kept closed.

In the case of this embodiment, the afterglow characteristic similar to that of an incandescent lamp can be obtained by appropriately setting the constants of the resistors R _{1 to} R ₃ and the capacitor C ₃ . (Embodiment 2) FIGS. 4 and 5 show another embodiment of the present invention. In the present embodiment, the functions of the high-frequency oscillator G ₂ ′ that generates the triangular wave signal f _S and the comparator CP ₁ that gradually reduces the on-duty of the high-frequency rectangular wave signal f _H are the same as those in the above-described embodiment. The features of
The method is characterized by the method of generating the comparison voltage V _X ′ to be compared with the triangular wave signal f _S and the method of maintaining the power supply of the main circuit X.

In this embodiment, no particular measures are taken to maintain the power supply of the main circuit X. That is, the main circuit X so as to maintain the power supply state of the smoothing capacitor C ₂ includes the main circuit X after off of the main circuit X of smooth power switch S by utilizing the charges of the capacitor C ₂ is there. Then, as described below, the output of the inverter circuit is gradually reduced after the power switch S is turned off,
Since the power consumption of the inverter circuit is reduced, the period during which the output of the inverter circuit drops below the discharge maintaining voltage of the discharge lamp DL after the power switch S is turned off is longer than the period of afterglow of an incandescent lamp or the like.

By the way, in the case of gradually darken the discharge lamp DL, a control to shorten the ON period of the switching element Q ₁ to Q ₄ is not performed, it is conceivable to simply increase the capacity of the smoothing capacitor C _2. In this case, the amount of light emission gradually decreases until the output voltage of the inverter circuit decreases to the voltage required to maintain the discharge of the discharge lamp DL, but the output voltage of the inverter circuit decreases to maintain the discharge of the discharge lamp DL. When the voltage drops below the required voltage, the discharge lamp DL is instantaneously extinguished, and the change in the amount of light emission at that time becomes sharp. Therefore, a sudden change in light occurs at the time of the final light extinguishing, so that a desired effect cannot be expected.

[0023] Therefore, in the case of this embodiment, instead of increasing the capacitance of the smoothing capacitor C _2, similar afterglow characteristics incandescent electrode by a control to shorten the ON period of the switching element Q ₁ to Q ₄ To get. Less than,
A circuit that generates the comparison voltage V _X ′ to be compared with the triangular wave signal f _S which is a feature of the present embodiment will be specifically described.
In the case of this embodiment, a comparator CP ₃ which compares the voltage V ₂ at the connection point between the input of the power switch S and the main circuit X with a reference voltage V _R2, on the output of the comparator CP _3, is off-controlled and 'switching element applying a voltage of the control power supply V _CC as the comparator CP ₁ (transistor) Q _X' comparison voltage V _X during on, compared by applying the voltage V ₂ at the time of off of the switching element Q _X 'divided voltage V _X dividing resistor R ₄ to generate a ', is provided with a R _5.

A power switch S is shown on the left side of FIG.
Is on, the voltage V _TwoIs the DC power supply V₁of
As shown in FIG.
Reference voltage V_R2And the comparator CP_ThreeOutput
It is low level. Therefore, the switch Q_X'But
ON and the comparison voltage V_X’As shown in FIG.
Almost control power supply V_CCVoltage is constant. Therefore,
During this period, the comparator CP₁The output of the high frequency
Square wave signal f_HThe on-duty is shown in FIG.
And the output of the inverter circuit is constant.
The discharge lamp DL is turned on, and the light emission amount Φ of the discharge lamp DL is almost one.
It is fixed.

When the power switch S is turned off as shown in FIG. 5A, the supply of power to the smoothing capacitor C ₂ is cut off, and the voltage V ₂ gradually decreases as shown in FIG. To decline. Then, when the voltage V ₂ drops below the reference voltage V _R2, the output of the comparator CP ₃ becomes high level, the switch element Q _X 'is turned off. As a result, the comparison voltage V _X ′ is thereafter determined by the voltage obtained by dividing the voltage V ₂ by the resistors R ₄ and R ₅ , and the comparison voltage V _X ′ decreases as the voltage V ₂ decreases. Therefore, on-duty of the rectangular wave signal f _H is reduced along with this, the output of the inverter circuit is reduced, the light emission amount Φ gradually decreases.

In this case, the output of the inverter circuit is reduced by setting the voltage dividing ratio of the resistors R ₄ and R _{5 and} the voltage of the triangular wave oscillator G ₂ ′ so as to decrease in accordance with the afterglow phenomenon of the incandescent lamp. That is, as described above, the power consumption of the inverter circuit decreases with the decrease in the output of the inverter, and the period from when the power switch S is turned off until the output of the inverter circuit falls to or below the discharge maintaining voltage of the discharge lamp DL is: since longer to decay phenomena or more periods, such as incandescent bulbs, it is so rapidly reduce the on-duty of the rectangular wave signal f _H to the higher drop in voltage V _2. By doing so, the light emission amount of the discharge lamp DL is already small before the light is almost extinguished by the time when the discharge lamp DL falls below the discharge maintaining voltage of the discharge lamp DL, and a sudden light emission occurs when the discharge lamp DL is extinguished. No change occurs.

This embodiment is more effective especially when the main circuit has a constant power function. Incidentally, is provided with a capacitor C ₄ via the diode D ₂ is the circuit unit for generating the control power V _CC, a period that allows the stably controlled by the control circuit unit described above as compared with the voltage drop V ₂ It is provided to make it slightly longer. (Embodiment 3) FIGS. 6 and 7 show still another embodiment of the present invention. In this embodiment, the present invention is applied to a discharge lamp lighting device having a constant power function. For the constant power control in the discharge lamp lighting device, a current detection circuit CD for detecting a lamp current I _DL flowing through the discharge lamp DL, so that the lamp current I _DL is constant in accordance with the output of the current detecting circuit CD And a PWM control circuit 1 for controlling the on-duty of the switching elements Q _{1 to} Q ₄ . here,
The output of the current detecting circuit CD is intended to detect the voltage V _D decreases with an increase of the lamp current I _DL as shown in Figure 7 (a). Then, the PWM control circuit 1 outputs the lamp current I _DL
When the smaller, to increase the on-duty of the switching elements of the inverter circuit, by increasing the power supplied to the discharge lamp DL, increases the lamp current I _DL, the lamp current I _DL increases Conversely, the inverter circuit The on-duty of the switching element is reduced, the power supplied to the discharge lamp DL is reduced, the lamp current I _DL is reduced, and the lamp current I _DL is controlled to be constant.

By the way, when the power switch S is turned off in this embodiment, in order to gradually reduce the lamp current I _DL, a constant voltage circuit 2 which uses a Zener diode ZD for stabilizing the voltage V _2, An adder A for adding the output voltage of the constant voltage circuit 2 and the detection voltage V _D of the current detection circuit CD.
DD is provided. When the power switch S is on, the output of the constant voltage circuit 2 is a Zener diode ZD
Is controlled to the Zener voltage constant, in this case, operation of controlling the lamp current I _DL as described above in accordance with the detected voltage V _D of the current detection circuit CD constant is performed.

When the power switch S is turned off, the smoothing capacitor
Sa C_TwoVoltage V _TwoIs the constant voltage circuit 2
When the voltage drops below the Zener voltage, the output of the constant voltage circuit 2 becomes flat.
Smoothing capacitor C_TwoDecreases with a decrease in the voltage of this
Sometimes, the run-off occurs with a decrease in the output voltage of the constant voltage circuit 2.
Current I_DLInput of the adder ADD as in the case where
And the output also decreases accordingly.
In the same manner as in each of the embodiments described above,
Can be gradually reduced to turn off the light. in this case
The degree of decrease in the output of the inverter circuit is the afterglow of the incandescent lamp
It goes without saying that the setting is made to match the phenomenon.

By the way, in the description of each of the above embodiments, the so-called dimming control by controlling the on-duty is performed.
Although the case where the discharge lamp DL is gradually darkened has been described,
For example, in the case where a resonance circuit is provided at the output of the inverter circuit and the dimming control is performed by shifting the switching frequency of the switching element of the inverter circuit from the resonance frequency of the resonance circuit, the dimming control by the frequency control gradually controls the discharge lamp DL. It can be darkened.

[0031]

According to the first aspect of the present invention, as described above, a DC power supply, an inverter circuit for converting the voltage of the DC power supply to an AC voltage, and a vehicle which is turned on by the output of the inverter circuit ,
Variable and discharge lamp that is used in headlights of dual, and off detecting means for the power switch detects that it has been turned off, the on-duty or the switching frequency of the switching elements of the inverter circuit within a predetermined time from the off time of the power switch Dimming control means for gradually reducing the amount of light emitted by the discharge lamp until the light is almost turned off, and an inverter circuit and dimming control means for maintaining lighting of the discharge lamp at least for a certain period of time after the power switch is turned off. Power supply means for supplying power to the discharge lamp, so that the discharge lamp can be kept lit even after the power switch is turned off, and the light emission amount of the discharge lamp is gradually reduced until the light is turned off. in the afterglow characteristics substantially the same conditions, by gradually darken the discharge lamp when off the power switch, the vehicle of f
This has the effect of reducing the psychological load on the driver and the oncoming vehicle due to the sudden turning off of the headlight , and improving safety.

According to a second aspect of the present invention, as described above, a DC power supply, an inverter circuit for converting the voltage of the DC power supply to an AC voltage, and a vehicle which is turned on by the output of the inverter circuit ,
A lamp is that release used headlight use, and a smoothing capacitor for supplying electric charge to the OFF state of the power switch as a power supply, a voltage detection means voltage across the smoothing capacitor is detected to be decreased below a predetermined voltage, Adjusting the on-duty or switching frequency of the switching element of the inverter circuit within a certain time from the point in time when the voltage across the smoothing capacitor falls below a predetermined voltage to gradually reduce the light emission amount of the discharge lamp until the light is almost turned off. Light control means, using the charge of the smoothing capacitor as a power source to operate each part of the subsequent stage of the power switch, to keep the discharge lamp lit even after the power switch is turned off, and Gradually reduce the amount of light emitted until it goes out, and in a state similar to the afterglow characteristics of incandescent bulbs,
To gradually darken the discharge lamp at the time off the power switch
Accordingly , the same effect as the first aspect can be obtained.

[Brief description of the drawings]

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

FIG. 2 is an operation explanatory view of the above.

FIG. 3 is an explanatory diagram of a PWM control method according to the first embodiment;

FIG. 4 is a circuit diagram of another embodiment.

FIG. 5 is an operation explanatory view of the above.

FIG. 6 is a circuit diagram of still another embodiment.

FIG. 7 is an explanatory diagram of the constant power operation according to the first embodiment.

FIG. 8 is a circuit diagram of a conventional example.

FIG. 9 is an operation explanatory view of the above.

FIG. 10 is an explanatory diagram of light emission characteristics when the power is cut off in the power supply system.

FIG. 11 is an explanatory diagram of the light emission characteristics of the incandescent lamp when the power is turned off.

[Explanation of symbols]

A Inverter circuit V ₁ DC power supply DL Discharge lamp S Power switch Q _{1 to} Q ₄ Switching element Ry ₁ relay r ₁ contact Q _X , Q _X 'Switch element G ₁ Low frequency oscillator G ₂ High frequency oscillator G ₂ ' Triangle wave oscillator CP ₁ ~ CP ₃ comparator C ₂ smoothing capacitor

Claims (2)

(57) [Claims] 1. A DC power supply, an inverter circuit for converting the voltage of the DC power supply into an AC voltage, is turned by the output of the inverter circuit, a lamp release that used headlights for vehicles, the power switch is turned off Off detecting means for detecting that the power has been turned off, and gradually changing the on-duty or the switching frequency of the switching element of the inverter circuit within a certain time from the time when the power switch is turned off until the light emission amount of the discharge lamp is almost turned off. Dimming control means for decreasing, an inverter circuit for maintaining lighting of the discharge lamp at least for a certain period of time from the time when the power switch is turned off , and
A discharge lamp lighting device comprising: power supply means for supplying power to the dimming control means . [2 claim] DC power supply, an inverter circuit for converting the voltage of the DC power supply into an AC voltage, is turned by the output of the inverter circuit, a lamp release that used headlights for vehicles, off of the power switch A smoothing capacitor that supplies charged electric power as a power source, voltage detecting means for detecting that the voltage across the smoothing capacitor has dropped below a predetermined voltage, and a fixed time from when the voltage across the smoothing capacitor has dropped below the predetermined voltage. Lighting control means for varying the on-duty or switching frequency of the switching element of the inverter circuit to gradually reduce the amount of light emitted from the discharge lamp until the lamp is almost turned off. apparatus.