JP2708824B2 - Discharge lamp lighting device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a discharge lamp lighting device for lighting a lamp at high frequency.

[Prior Art] As a discharge lamp lighting device for lighting a lamp at a high frequency using a conventional inverter, various inconveniences caused by overcurrent, overvoltage or abnormal heat generation caused by abnormal operation or load are prevented. Some are equipped with means. Sixth
FIG. 1 is a view showing a conventional discharge lamp lighting device provided with the above means. This discharge lamp lighting device is proposed in Japanese Patent Application Laid-Open No. Sho 56-22583.
A push-pull inverter composed of Q ₁ , Q ₂ and a transformer T ₁ is used. This inverter 1 operates using a DC power supply obtained by rectifying an AC power supply AC by a diode bridge DB as a power supply.
It is supplied to the lamp l through T ₁ to turn on the lamp l.

In the discharge lamp lighting device, for example, or cause interlayer short in trans T _1, or when the lamp l is or half-wave discharge becomes end of life, the overcurrent flows through the transistor Q _1, Q _2, the transformer T ₁ is Abnormal heat generation compared to normal. For this reason, each part of the discharge lamp lighting device is adversely affected. Therefore,
In this discharge lamp lighting device detects abnormal heating of the transformer T ₁ of the this time, there is an abnormality detection control circuit 2 for stopping the oscillating operation of the inverter 1 is provided. The abnormality detection control circuit 2, the abnormal heat generation of the transformer T ₁ when the temperature-sensitive element R _T is detected by turning on the switching element Q _3, a short circuit between the base and emitter of the transistor Q _1, Q ₂ In this case, the operation of the inverter 1 is stopped.

However, in the abnormality detection control circuit 2, from the time of abnormality such as an interlayer short circuit occurs to the operation of the inverter 1 is stopped, there is a problem that results in a delay of only the thermal time constant of the components such as the transformer T ₁ and the inverter 1 is transformer T ₁ is cooled after being oscillated stopped, the inverter 1 is a problem that work again.

Incidentally, as this type of discharge lamp lighting device, as shown in FIG. 7, a choke coil CH _1, the switch SW ₁ Tokyo becomes dimmer circuit 3 for short-circuiting open ends of the choke coil CH _1, trans there is provided between the secondary and the lamp l of T _1. In the light control circuit 3, when turning off the switch SW _1, the choke coil CH ₁ is connected in series with the lamp l, it reduces the power supplied from the inverter 1 to the lamp l, is ramped l is dimming . And the switch
When SW ₁ is turned on, lamp 1 is directly connected to the output of inverter 1 and lamp 1 is fully lit. In the discharge lamp lighting device, adjusting if at the time the optical half-wave discharge of the interlayer short circuit or lamp l of the transformer T ₁ is generated, because the power supplied to the lamp l is reduced, the calorific value of the transformer T ₁ is the total It is smaller than when lit. For this reason, even in the event of an abnormality, the temperature sensing element _RT cannot detect the abnormality, and the operation of the inverter 1 cannot be stopped. In such a case, the lamp 1 can be turned on at the time of dimming, but the lamp 1 cannot be turned on at the time of full lighting. That is,
The abnormality detection sensitivity is not uniform between full lighting and dimming. Here, even if the above abnormality occurs during dimming, for example, since the stress on the elements such as the transistors Q ₁ and Q _{2 of the} inverter 1 does not reach the level at which the element is destroyed, the abnormality detection control circuit 2 is sufficient. Although there is a thought that there is, for example, when a half-wave discharge occurs at the end of the life of the lamp l, when the lamp l is fully lit, a stress that may obviously destroy the element is applied, Needless to say, it is preferable that the abnormality detection control circuit 2 be operated at times.

FIG. 8 shows a discharge lamp lighting device in which the configuration of the abnormality detection control circuit 2 is different, and a transformer in which the primary sides (primary windings L ₁₁ and L ₁₂ ) are connected in series to the transistors Q ₁ and Q ₂ , respectively. The operation of the inverter 1 is stopped by detecting an overcurrent flowing through the transistors Q ₁ and Q ₂ using T ₂ . More specifically, when an overcurrent flows through the transistors Q ₁ and Q ₂ , the transformer
When the voltage induced on the secondary side of T ₂ is rectified by diodes D ₁ and D ₂ , and the rectified output is divided by resistors R ₁ and R ₂ , and the voltage becomes higher than the specified voltage of Zener diode ZD ₁ , turns on the switching element Q ₃ to reduce or cut the base current of the transistor Q _1, Q _2, stops the operation of the inverter 1. Also in the discharge lamp lighting apparatus provided with the abnormality detection control circuit 2, when adding the dimming function described above, abnormality was also an abnormality detection output during dimming (output of the transformer T ₂₎
There lowered, not more than Zener diodes specified voltage set by ZD _1, there is a problem that can not abnormality detection.

FIG. 9 shows a conventional example provided with another abnormality detecting function. The discharge lamp lighting device as an inverter, transistor Q _5, Q _6, c self-excited constituted by the transformer T ₃ and the capacitor C ₆ - Yes using the full-bridge inverter, the trigger element Q ₉ of the starting circuit 4 it is intended to operate the inverter 1 by applying a starting pulse to the transistor Q ₆ through. In this discharge lamp lighting device, the lamp 1
Is provided with an abnormality detection control circuit 5 for detecting an abnormality of the above. In the abnormality detection control circuit 5, the resistance through the diode D ₃
The lamp voltage divided by R ₃ and R ₄ is the Zener diode ZD ₂
If equal to or greater than the specified voltage, the transistor Q ₈ is turned on,
When the transistor Q ₇ is turned off, SCRQ ₁₀ is turned on, performs control to suppress or stop the switching operation of the transistor Q _5, Q _6.

However, also in this discharge lamp lighting device, when the above-described light control circuit 3 is added as shown in FIG. 10, there is a problem that an abnormality cannot be detected during light control.

[Problems to be Solved by the Invention] 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 detecting an abnormality even during dimming. Is to do.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes abnormality detection control means for stopping the operation of the inverter when an abnormality occurs, as the abnormality detection sensitivity increases as the dimming depth increases. .

[Operation] As described above, according to the present invention, the abnormality detection sensitivity of the abnormality detection control means is increased as the dimming is deepened, so that the decrease in the power supplied from the power supply at the time of dimming is reduced. This makes it possible to detect an abnormality at the time of dimming as in the case of full lighting.

[Embodiment] As shown in FIG.
An abnormality detection unit 7 for detecting an abnormality of the inverter 1 or an abnormality of the lamp 1, a reference setting unit 8 for setting a reference voltage according to the dimming signal, a reference voltage set by the reference setting unit 7, and an abnormality detection unit And a control unit 10 for controlling the operation of the inverter 1 with the output of the comparison unit 9. The abnormality detection control circuit 6 is constituted by the comparison unit 9 according to the dimming signal. By setting the reference voltage, the abnormality can be detected in any dimming state.

FIG. 2 shows a specific circuit of this embodiment. A half-bridge inverter is used as the inverter 1 of the present embodiment, and FE is used as a switching element of the half-bridge inverter.
TQ ₁₁ and Q ₁₂ are used. Inverter 1 is an AC power supply
Together with full-wave rectified by the diode bridge DB, and operates the smoothed output by the capacitor C ₁ as a power source. Load circuit, the lamp l and a capacitor C ₂ and the choke coil CH ₃
Yes constituted by a resonance circuit composed of, is connected to both ends of the FETs Q _12. The capacitor C _3, together act as a capacitor for cutting direct current, electric charge charged in the capacitor C ₃ is inverter 1 is used as a power source for performing an oscillation operation.

The dimming control of the lamp 1 is performed by the control circuit 11 of the inverter 1. The control circuit 11 controls the FETQ ₁₁ ,
It intended called frequency control type where varying the switching frequency of the Q _12, general-purpose IC for oscillating a signal of a frequency corresponding to the switching frequency (e.g., MyuPC494 etc.) and 12, the FETs Q _11, Q ₁₂ according to the output of the IC12 A drive unit 13 for driving each,
Dimming control unit that varies the oscillation output of IC12 according to the dimming signal
It is composed of 14. Amplifier dimming controller 14, for amplifying a buffer B ₁ to prevent a change in the voltage level of the (DC voltage in this second figure) increased to dimming signal input impedance, the output of the buffer B ₁ Yes constituted by the a _1, by changing the potential of the control terminal of the IC 12, IC 12
Is controlled to change the frequency of the output signal (terminal,). The drive unit 13 includes an inverter buffer I ₁ , a FET Q ₁₃ and a transformer T _4, and an inverter buffer I ₂ , a FET Q ₁₄ and a transformer T ₅ , respectively. Note that the circuits constituting the abnormality detection control circuit 6 to the control circuit 11 and later steps down by a transformer T _6, a voltage Vcc which is a constant voltage the voltage charged in the smoothing capacitor C ₄ with constant voltage IC19 Operates as a power supply.

Dimming signal via a buffer B ₁ and the amplifier A _1, A ₂ IC12
, And the IC 12 outputs a signal having a frequency corresponding to the potential of the control terminal at this time. Terminal of the IC 12, FETs Q _11, the drive unit 13 in accordance with the output signal from the Q
₁₂ is alternately turned on and off to supply a high frequency output to the lamp l.

Next, the abnormality detection control circuit 6 will be described. The abnormality detection section 7 of the abnormality detection control circuit 6 includes a diode D ₄ , resistors R ₅ and R ₆ and a capacitor C ₅ , and detects a lamp voltage. Reference setting unit 8 Yes constituted by the control circuit buffer B ₂ in the same manner as the dimming control unit 14 of the 11 and the amplifier A _2, to create a reference voltage of the comparator unit 9 in response to the dimming signal. Control unit 10 includes a flip-flop 15 for holding the output state of the comparator unit 9, an AND gate 16 and 17, Yes constituted by an inverter buffer I _3, I _4, abnormal output of the detector 7 is equal to or higher than the reference voltage And gate 1
In steps 6 and 17, the output of the IC 12 via the inverter buffers I ₁ and I ₂ is blocked from being input to the drive unit 13 and the operation of the inverter 1 is stopped.

For example, when the emitter of one of the filaments of the lamp 1 is exhausted and becomes an Emiless state, the lamp voltage increases and the output of the abnormality detection unit 7 also increases. When the output of the abnormality detection unit 7 rises to the reference voltage abnormality set by the reference setting unit 8, the output of the comparison unit 9 goes low. When the output obtained by inverting the low-level output at inverter buffer I ₃ are input to the flip-flop 15, flip-flop
15 output becomes high level, and this state is maintained.
The low level output obtained by inverting this time the output of flip-flop 15 by the inverter buffer I _4, AND gates 1
The input of the output signal of the IC 12 to the FETs Q ₁₃ and Q ₁₄ is blocked by the FETs 6 and 17, so that the operation of the inverter 1 is stopped.

By the way, the voltage level of the dimming signal of the present embodiment decreases as the dimming becomes deeper. Therefore, as the dimming becomes deeper, the reference voltage of the comparison unit 9 set by the reference setting unit 8 also decreases, and an abnormality can be detected even when the output of the abnormality detection unit 7 is low. That is, as the dimming becomes deeper, the abnormality detection sensitivity of the abnormality detection control circuit 6 increases. Therefore, the decrease in the power supplied from the inverter 1 to the lamp 1 during dimming can be compensated for by increasing the sensitivity of the abnormality detection control circuit 6, and the abnormality detection can be appropriately performed even during dimming as in the case of full lighting. I can do it for sure.

Embodiment 2 FIG. 3 is a diagram showing another embodiment of the present invention. In this embodiment, the output level of the abnormality detecting section 7 is changed according to the dimming signal. In the case of the present embodiment, the reference voltage of the comparison unit 9 is constant.

FIG. 4 shows a specific configuration of the abnormality detection unit 7 of this embodiment.
Respectively of this the abnormality detecting unit 7 resistor in parallel with the voltage dividing resistors R ₆ R ₇ to R ₉ and transistor Q ₁₅ to Q ₁₇ is connected a series circuit connected in series, detection in response to the level of the dimming signal sensitivity Control circuit
18 are to carry out the conduction control of the transistor Q ₁₅ to Q ₁₇ in the output of. For example, in the case of full lighting, transistor Q
₁₅ to Q ₁₇ all turned on, abnormal lowering the output potential of the detection unit 7, the abnormality detection control circuit and the detection sensitivity of 6 low dimming time off the transistor Q ₁₅ to Q ₁₇ in accordance with the dimming state Then, the output potential is raised to increase the detection sensitivity. In the case of the present embodiment as well, the abnormality can be detected accurately even during light control.

In the above description, the case where one abnormality detection control circuit 6 detects an abnormality at the time of dimming has been described. However, as shown in FIG. 5, a plurality of abnormality detection control circuits (two in FIG. 5).
Are provided. 6) may be provided, and the abnormality detection control circuit 6 of the abnormality detection sensitivity may be appropriately selected according to the dimming signal.

[Effect of the Invention] As described above, the present invention includes abnormality detection control means for increasing the abnormality detection sensitivity as the dimming becomes deeper and stopping the operation of the inverter in the event of an abnormality. The decrease in the supplied power can be compensated for by the abnormality detection control means increasing the abnormality detection sensitivity, and therefore, there is an effect that an abnormality can be detected at the time of dimming as in the case of full lighting.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration of one embodiment of the present invention, FIG. 2 is a concrete circuit diagram of the above embodiment, FIG. 3 is a block diagram showing a circuit configuration of another embodiment, and FIG. FIG. 5 is a block diagram showing a circuit configuration of still another embodiment, FIG. 6 is a circuit diagram of a conventional example, and FIG. 7 is a main part in the case where a dimming circuit is provided thereon. FIG. 8 is a circuit diagram of another conventional example, FIG. 9 is a circuit diagram of still another conventional example, and FIG. 10 is a main part circuit diagram in the case where a dimming circuit is provided thereon. 1 is an inverter, 6 is an abnormality detection control circuit, 11 is a control circuit, and 1 is a lamp.

Claims (1)

(57) [Claims] 1. An inverter that lights a lamp by supplying high-frequency power to the lamp, a dimming control unit that performs dimming control according to a dimming signal, and an abnormality detection sensitivity increases as the dimming depth increases. A discharge lamp lighting device comprising: abnormality detection control means for stopping the operation of the inverter at the time.