JP3280390B2 - 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 apparatus for lighting a high pressure discharge lamp by switching a switching element and applying a voltage generated from a DC power supply to the high pressure discharge lamp.

[0002]

2. Description of the Related Art FIG. 5 shows a conventional discharge lamp lighting device of this kind. In this discharge lamp lighting device, the voltage V _{1 of the} DC power supply ₁
Is stepped down by a step-down chopper circuit 10 including a transistor Q ₁ , a diode D ₁ , a choke coil L ₁ and a capacitor C ₁ , and the step-down voltage is applied to the high-pressure discharge lamp 2 to perform DC lighting. In this discharge lamp lighting device, the voltage between both ends of the high pressure discharge lamp 2 (hereinafter, referred to as a lamp voltage)
By varying the on-duty of the transistor Q ₁ in accordance with a change in V ₂ Yes so as to appropriately adjust the power supplied to the high-pressure discharge lamp 2, a pulse width corresponding to the change of the lamp voltage V ₂ of the high-pressure discharge lamp 2 comprises 'and, the control circuit 11' control circuit 11 for outputting a signal turning the transistor Q ₁ in accordance with the output of a drive circuit 4 for turning off. here,
The control circuit 11 'is the pulse width control IC (for example, manufactured by Texas Instruments TL494, etc.) which was used 3, in this IC3 to the external resistor R ₁ to R ₆ and the operational amplifier 5 to be built, the lamp voltage V ₂ A differential amplifier circuit for outputting a differential output between a voltage obtained by dividing the voltage by resistors R ₁ and R ₂ and a reference voltage formed by dividing the voltage Vref by resistors R ₅ and R ₆ , and an external resistor Rs and capacitor Cs
Oscillation circuit 7 that outputs a sawtooth wave having a frequency determined by the time constant of
And a comparator for comparing the output of the oscillation circuit 7 with the divided voltage of the resistors R ₇ and R ₈ by the built-in operational amplifier 6 and the voltage dividing resistors R ₇ and R ₈ for dividing the voltage Vref. I have.

[0003] Also, the drive circuit 4, are constituted by a pulse transformer PT ₁ and the transistor Q ₁₀ and the resistor R _9, R _10. In the control circuit 11 ′, the lamp voltage V ₂
When but rises, the output of the differential amplifier circuit is reduced, the step-down chopper circuit 10 from the pulse width control I C3 can this <br/>
Output to increase the on-duty of transistor Q ₁ is obtained. However, the maximum on-duty it is limited by the output of the co-down <br/> comparator. Incidentally, the maximum on-duty can be increased by reducing the voltage across the resistor R _8.

[0004] Further, specifically, the control circuit 11 'will control the on-duty of the transistor Q ₁ as follows.
That is, when the DC power supply 1 is supplied and the high-pressure discharge lamp 2 is in a no-load state, the lamp voltage V ₂ is almost equal to the DC power supply 1.
And has a no-load voltage V ₀₂ equals the voltage V _1. As starting to light the high-pressure discharge lamp 2 when this (that is, as the high-pressure discharge lamp 2 lamp voltage drops on) on-duty I has a maximum (D in FIG. 6).
Then, when the high-pressure discharge lamp 2 shifts from glow discharge to arc discharge to start, immediately after the start, the lamp voltage V ₂
Becomes 0 V (the actual lamp voltage V ₂ is several tens V). At this time, the voltage V ₁ of the DC power supply ₁ is almost equal to the choke coil L ₁
Is applied to the lamp current I ₂ is determined by the on- <br/> Yute I transistor Q _1. Here, immediately after the start-up is controlled on-duty it is small as shown in the vicinity of A in FIG. 6, thereby the lamp current I ₂ is prevented from becoming an overcurrent. When the high-pressure discharge lamp 2 is started in this way, thereafter, the impedance of the high-pressure discharge lamp 2 increases. When fixing the on-duty I in this by A in FIG. 6,
Since the lamp current I ₂ is reduced, in order to flow the appropriate current to the high-pressure discharge lamp 2, intends row called warm-up to increase the on <br/> duty with the increase of the lamp voltage V ₂
(Wherein, with increasing lamp voltage V ₂ on-
Warm-up operation period during which the duty is increased
). Thus the ramp voltage V ₂ by controlling the on-duty it so that the rated lamp voltage V _01, the high-pressure discharge lamp 2 is so turned steady. And later on-duty I of the transistor Q ₁ in accordance with the variation of the lamp voltage V ₂
To maintain the lamp voltage V ₂ at the rated lamp voltage V ₀₁ . However, at the end of life or the like of the high-pressure discharge lamp 2 can not be controlled to turn on <br/> Deyute lamp voltage V ₂ no matter how large the I becomes the rated lamp voltage V _01, in this case unusually Since large lamp power is supplied to the high-pressure discharge lamp 2, the transistor Q _{1 is} used to prevent this.
'S on-duty it are to be limited by the control circuit 11 '. This maximum on-duty is set by a comparator that compares the voltage between both ends of the resistor R ₈ and the output of the oscillation circuit 7.

[0005]

However, the above-described discharge lamp lighting device has the following problems. That is, in response to an increase in the lamp voltage V ₂ in the vicinity of the steady lighting-duty
When performing control to increase the I, for example, the lamp voltage V ₂ is increased, which increases the lamp <br/> current I _2-duty I is increased with further increase in the lamp current I ₂ repeated operation of the lamp voltage V ₂ is increased in accordance with the lamp voltage V ₂ is too increased, despite this order are limiting the maximum on-duty as shown in B-D shown in FIG. 6 There were times when it went out.

[0006] The high-pressure discharge lamp 2 has a constant voltage characteristic in which the lamp voltage does not fluctuate even when the lamp current is changed in a steady lighting state, and the lamp current is kept constant when the lamp current is changed. There are two types, one having a constant current characteristic in which the lamp voltage changes. Here, the high-pressure discharge lamp 2 which causes the above-described phenomenon has the latter constant current characteristic. Examples of the high-pressure discharge lamp 2 exhibiting such constant current characteristics include a high-pressure sodium lamp and a high-color rendering high-pressure sodium lamp. Some metal halide lamps (in which a metal iodide is sealed in a mercury lamp to improve luminous efficiency, color rendering, etc.) exhibit constant current characteristics depending on the type and amount of the metal iodide.

[0007] That is, in the discharge lamp lighting device for lighting a high pressure discharge lamp 2 having a constant current characteristic, when the control to increase the on-duty I with increasing lamp voltage V _2,
The high-pressure discharge lamp 2 cannot be stably turned on. Also,
Even if the stationary lighting, the lamp voltage V ₂ is much variation in each high-pressure discharge lamp 2, the light color changes (rise to color variation), practical problems.

[0008] Therefore, it is conceivable to perform control in the opposite direction of increasing the on-duty I along with the descent of the ramp voltage V ₂ in the A-B in FIG. 6, an excessive current at start in this case is There is a problem that flow, and because no appropriate current to the operation period of the worm up flows, the lamp voltage V ₂ is not completely raised, the problem that remains in a low state of the lamp voltage V ₂ without shifting to steady lighting Cause

[0009] The present invention has been made in view of the above, it is an object of high having a constant current characteristic
And to provide a discharge lamp lighting device which can be smoothly is shifted to the steady lighting is lit stably圧放lamp from startup.

[0010]

According to the present invention, in order to achieve the above object, a high voltage discharge lamp having a constant current characteristic is applied to a high voltage discharge lamp having a constant current characteristic by switching a switching element and applying a voltage generated from a DC power supply. A discharge lamp lighting device for illuminating a lamp, comprising a detecting means for detecting a lamp voltage of the high-pressure discharge lamp, a lamp which warms up from a lamp voltage at the time of starting , is lower than a lamp voltage of steady lighting, and is capable of shifting to steady lighting. Up to the specified voltage
A switch for increasing the power supplied to the high pressure discharge lamp when the lamp voltage detected by the detecting means increases.
Controlling the on-duty of the ring element, from the specified voltage
Until the lamp voltage for steady lighting is reached, the detection means
When the detected lamp voltage rises , the on- duty of the switching element is controlled so as to reduce the power supplied to the high-pressure discharge lamp, and the lamp detected by the detection means is controlled.
Control means for controlling the on-duty so as to stop decreasing the power supplied to the high-pressure discharge lamp when the lamp voltage reaches a lamp voltage near the end of life of the high-pressure discharge lamp that is higher than the lamp voltage for steady lighting. I have.

[0011]

According to the present invention, the power supply to the high-pressure discharge lamp is suppressed by the control means in the vicinity of the steady-state operation of the high-pressure discharge lamp having the constant current characteristic by the provision of the above-mentioned structure, and the lamp voltage is maintained until the lamp voltage rises or falls. The high pressure discharge lamp is smoothly shifted from starting to steady lighting so as not to rise. Moreover ,
Lower than the lamp voltage for steady lighting and transition to steady lighting possible
Lamp voltage for steady lighting from the specified lamp voltage
The control means operates in the direction of suppressing the lamp voltage of the high-pressure discharge lamp until the pressure reaches, so that the variation in the lamp voltage of each high-pressure discharge lamp can be suppressed and reduced, and the light color can be reduced for each high-pressure discharge lamp. It is possible to prevent the change. Further, when the end of the life of the high-pressure discharge lamp is approaching, the control means operates to stop the decrease in the power supplied to the high-pressure discharge lamp, thereby preventing the high-pressure discharge lamp from going out. is there.

[0012]

(Embodiment 1) FIG. 1 shows an embodiment of the present invention. The discharge lamp lighting <br/> basic construction of equipment of this embodiment is a substantially same as the conventional configuration shown in FIG. 5
Te, is applied to the high-pressure discharge lamp 2 by lowering the voltage of the dc power supply 1 in the step-down chopper circuit 10, the transistor Q ₁ in accordance with the output of the main circuit unit, and a control circuit 11 for DC lighting the high pressure discharge lamp 2 5 is the same as that in FIG. 5, and in this embodiment, the configuration of the control circuit 11 is different. The control circuit 11 of the present embodiment, as shown in FIG.
The difference between the resistances R _1, R ₂ for detecting a lamp voltage V _2, the amplification circuit 8 amplifying a difference between the resistors R _1, the divided voltage with a predetermined voltage by R _2, and the divided voltage and the ground potential An oscillation circuit 7 for outputting a sawtooth wave having a frequency determined by the time constant of the resistor Rs and the capacitor Cs;
Constituted by a comparator 12 for outputting a pulse width signal which determines the on-duty I of the transistor Q ₁ by comparing the outputs of the oscillation circuit 7 via a respective diode D _2, D ₃ of the respective amplifier circuits 8 and 9 It is. Here, the amplifier circuit 8 may be composed of, for example, an operational amplifier 13 and resistors R ₁₁ and R ₁₂ as shown in FIG. 2A, and the amplifier circuit 9 is an operational amplifier as shown in FIG. 14 and resistors R ₁₃ and R ₁₄ . In FIG.
Width circuit 8 amplification factor is determined by the resistors R ₁₁ and R _12,
The other amplifying circuit 9 amplification factor determined by the resistor R ₁₃ and R ₁₄
The control circuit 11 shown in FIG.
Diode D connected in forward direction to each of circuits 8 and 9
The _1, D _2, compares the outputs of the two amplifier circuits 8 and 9,
The higher voltage is input to the comparator 12,
Determine the on-duty. To explain further, the lamp
The voltage V ₂ is low and the output voltage of the amplifier 9
When the voltage is larger than the input voltage, the comparator shown in FIG.
Input voltage V ₃ of the 12 is dominated by the output of the amplifier circuit 9, O
Duty is determined. In addition, the rise of the lamp voltage V ₂
The output voltage of the amplifier circuit 9 further decreases, and the output of the amplifier circuit 8
When the voltage is larger, the input voltage of the comparator 12
V ₃ is dominated by the output of the amplifier circuit 8 and the on-duty
Will be decided.

[0013] Now, lamp voltage V ₂ is the amplification circuit 8 low
When the output voltage is smaller than the output voltage of the amplifier circuit 9
The output of the amplifier circuit 9 to the lamp voltage V ₂ is the output voltage decreases with increasing dominated the input of the comparator 12
I do. In this case, as the ramp voltage V ₂ increases, the period during which the output of the oscillation circuit 7 is larger than the output of the amplifier circuit 9 becomes longer, and the high-level period of the pulse width signal output from the comparator 12 becomes longer. Become. Therefore, (the operation of the A-B in FIG. 6) prior in the same manner as described in the example of FIG. 5, the control circuit 11 to increase the on-duty with the increase of the lamp voltage V ₂ is to operate.

[0014] Then, the output voltage of the lamp voltage V ₂ is high amplification circuit 8 is larger than the output voltage of the amplifier 9
In this case, the output of the amplifier 8 whose output increases as the ramp voltage V ₂ rises dominate the input of the comparator 12.
And, the control circuit 11 operates to reduce the on-duty with the increase of the lamp voltage V _2. When showing the relationship between the input voltage V ₃ of the lamp voltage V ₂ and the comparator 12 the operation of the control circuit 11 becomes as shown in FIG. 3 (a), the output voltage of the ramp voltage V ₂ is lower amplification circuit 8 amplification
When the output voltage is smaller than the output voltage of the circuit 9, A'-
B 'is the input voltage V ₃ changes as the lamp voltage V ₂ is high
And the output voltage of the amplifier circuit 8 becomes equal to the output voltage of the amplifier circuit 9.
It becomes larger than the input voltage V ₃ as B'-C 'in FIG changes. If this shows the relationship between the lamp voltage V ₂ and the on-duty, as shown in FIG. 3 (b).

Here, the lamp voltage V _{2 at the} point B ′ is determined at a warm-up time when the high-pressure discharge lamp 2 is warmed up as appropriate from the lamp voltage at the time of starting (the warm-up state is not insufficient, and the lamp voltage V ₂ is increased). Wo smoothly from migratable state) in voltage to a steady lights (lamp voltage starting point without the high pressure discharge lamp is goes out from the start to
And the lamp voltage is lower than the
(Specified voltage, which is a lamp voltage that can be shifted to the normal lighting) . Therefore, the lamp voltage V ₂ in FIG.
Start or we warm up period of A-B to increase the on-duty by an increase in the increase of the lamp voltage V ₂
And the period until the voltage reaches the specified voltage (hereinafter, the operation mode of the control circuit 11 at this time is referred to as a start mode).
Period of B-C to decrease the on-duty by the rising of the lamp voltage V ₂ is the steady state lighting from the specified voltage lamp
This is a period (second period) during which the voltage shifts (the operation mode of the control circuit 11 at this time is referred to as a lighting mode).

[0016] By performing the control as described above, the control circuit 11 in the vicinity of the steady lighting operates in the lighting mode, when the lamp voltage V ₂ is increased, in a direction to suppress the lamp current decreases the on-duty I since that are controlled, a high-pressure discharge lamp 2 is also have a constant current characteristic, the lamp voltage V ₂ is prevented from causing goes out too elevated. Moreover, operating the control circuit 11 as described above, even if there are variations in lamp voltage V ₂ to each high-pressure discharge lamp 2, so that the control circuit 11 suppress variations in lamp voltage V ₂ by the control of the lighting mode work, Thus as compared with the case of lighting a high pressure discharge lamp 2 of copper iron type ballasts, it can be very reduce the variation in lamp voltage V _2. Therefore,
Variations in color temperature can also be suppressed, and changes in light color are reduced.

[0017] In the control of the lighting mode of the control circuit 11 described above, when the high-pressure discharge lamp 2 becomes higher lamp voltage V ₂ becomes end of life, the on-duty I becomes very small, a high pressure discharge lamp 2 may go out. Therefore, in the case of high lamp voltage V ₂ to a certain degree or more, it is desirable to control so as not to reduce the on-duty I any more. In this case, FIG.
The zener diode ZD may be connected to the output of the amplifying circuit 8 in the middle as shown by a broken line, and control may be performed so that the output of the amplifying circuit 8 does not increase to a certain degree or more. In other words,
3 in (a) to control the input voltage V ₃ at the position of the broken line. The relationship between the lamp voltage V ₂ and the on-duty I at this time is as shown in FIG. 3 (c), C-D in the figure shows the restriction mode of the on- <br/> Yute I. In addition to the case the high-pressure discharge lamp 2 is end of life, when the high-pressure discharge lamp 2 is abruptly lamp current drops, the high-pressure discharge lamp 2 in order to have a negative characteristic, the lamp voltage V ₂ rises abruptly Cause a phenomenon. Therefore, even in such a case, there is a function of preventing the high-pressure discharge lamp 2 from going out.

Further, by controlling the starting mode of the control circuit 11, the high pressure discharge lamp 2 can be switched to stable lighting in a short time. In other words, conventionally, both the starting and the stable lighting were satisfied in one control mode.
Although it was difficult to balance both, the start mode and the lighting mode can be divided into the start mode. It is possible to shift to stable lighting. Further, when the control mode of the control circuit 11 is set to two as described above, there is an advantage that the degree of freedom in design is greatly increased.

(Embodiment 2) FIG. 4 shows another embodiment of the present invention, in which the output of a step-down chopper circuit 10 is applied to a high-pressure discharge lamp 2 via an inverter circuit 15 having a full bridge configuration. Transistor Q ₁
Are switched at a high frequency, the transistors Q _{2 to} Q ₅ of the inverter circuit 15 are switched at a low frequency, and a rectangular wave current flows through the high pressure discharge lamp 2. Note that the control circuit 11 includes a circuit for controlling the switching of the transistor Q ₂ to Q _5, the transistor Q ₁ is operation is controlled in the same manner as described in the above embodiments. In this embodiment, since the high-pressure discharge lamp 2 is AC-lit, it is a more preferable lighting method for the high-pressure discharge lamp 2 than the above-described embodiment, and advantages such as a longer life of the high-pressure discharge lamp 2 can be obtained.

As described above, the present invention can be applied to any of DC lighting, rectangular wave lighting and high frequency lighting. In the above case, the on-duty control has been described.
May be a frequency control, short is up to the warm-up time of the high-pressure discharge lamp 2 is Ru is appropriately warmed up to increase the power supplied to the high-pressure discharge lamp 2, during warm-up
After reaching the point, it can be controlled to decrease it. Furthermore, although in the case described above had to control the on-duty I in accordance with the lamp voltage V _2, if the lamp characteristic that can determine the warm-up state of the high-pressure discharge lamp 2, according to other lamp characteristics-duty May be controlled.

[0021]

As described above, the present invention relates to a discharge lamp lighting apparatus for lighting a high-pressure discharge lamp by applying a voltage generated from a DC power supply to a high-pressure discharge lamp having constant current characteristics by switching a switching element. , comprising detection means for detecting a lamp voltage of the high pressure discharge lamp, the starting point lamp
Warm-up from voltage and from lamp voltage of steady lighting
Specified that the lamp voltage is low and the lamp can be switched to steady lighting.
Up to the voltage, the lamp detected by the detection means
Controls the on-duty of the switching element to increase the power supplied to the high pressure discharge lamp voltage rises, until the lamp voltage steady lighting from the specified voltage
The lamp voltage detected by the detecting means is raised
Scan to reduce the power supplied to the high pressure discharge lamp and
Controlling the on-duty of the switching element, wherein the detection hand
The lamp voltage detected by the step is
To the lamp voltage near the end of life of the high- pressure discharge lamp
Then, since the control means for controlling the on-duty so as to stop the reduction of the power supplied to the high-pressure discharge lamp is provided, the control means controls the high-pressure discharge lamp by the control means in the vicinity where the high-pressure discharge lamp having a constant current characteristic is steadily lit. The high-pressure discharge lamp can be smoothly shifted from starting to steady lighting without suppressing the electric power supplied to the lamp and preventing the lamp voltage from rising until the lamp goes out. And steady lighting
Run that is lower than the lamp voltage of
From the specified voltage, which is the lamp voltage, to the lamp voltage for steady operation
Since the control means operates in the direction of suppressing the lamp voltage of the high-pressure discharge lamp, the variation of the lamp voltage for each high-pressure discharge lamp can be suppressed and reduced, and the light color can be prevented from changing for each high-pressure discharge lamp. . Further, when the high pressure discharge lamp is nearing the end of its life, the control means operates so as to stop decreasing the power supplied to the high pressure discharge lamp, thereby preventing the high pressure discharge lamp from going out.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a main part of an embodiment of the present invention.

FIGS. 2 (a) and 2 (b) are specific circuit diagrams of constituent circuits of the above.

FIGS. 3 (a) to 3 (c) are operation explanatory diagrams of the above.

FIG. 4 is a circuit diagram of another embodiment.

FIG. 5 is a circuit diagram showing a conventional example.

FIG. 6 is an operation explanatory view of the above.

[Explanation of symbols]

1 DC power source 2 high-pressure discharge lamp 4 drive circuit 7 oscillator 8, 9 amplifying circuit 10 a step-down chopper circuit 11 control circuit 12 comparator Q ₁ transistor R _1, R ₂ resistor

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-57-46499 (JP, A) JP-A-62-123695 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05B 41/24-41/29

Claims (1)

(57) [Claims] 1. A discharge lamp lighting device for lighting a high pressure discharge lamp by applying a voltage generated from a DC power supply by switching a switching element to a high pressure discharge lamp having a constant current characteristic. Detecting means for warming up from the lamp voltage at the time of starting up to a specified voltage which is lower than the lamp voltage for steady lighting and is a lamp voltage which can shift to steady lighting.
When the lamp voltage detected by the detection means rises , the switch is made to increase the power supplied to the high-pressure discharge lamp .
Controlling the on-duty of the grayed element, a constant from the prescribed voltage
It is up to the lamp voltage of the normal lighting, by the detection means
Controlling the detected lamp voltage is on de <br/> Yuti switching element to reduce the power supplied to the high pressure discharge lamp to rise, was detected by the detection unit lamp
When the voltage of the high- pressure discharge lamp becomes higher than the lamp voltage of the steady-state lighting near the end of the life of the high-pressure discharge lamp, control means for controlling the on-duty so as to stop reducing the power supplied to the high-pressure discharge lamp is provided. Discharge lamp lighting device characterized by the above-mentioned.