JPS6324320B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a discharge lamp lighting device that lights two discharge lamps in series.

[Background Art] Conventionally, this type of discharge lamp lighting device that lights two discharge lamps in series has been configured as shown in FIG. 3. That is, in Fig. 3, V _AC is an AC power supply, T is a lead peak type ballast, C ₁ is a phase advance capacitor, C ₀ is a starting compensation capacitor, and R ₁
is a discharge resistor, and F ₁ and F ₂ are discharge lamps. The lead peak type ballast T has a slit in the iron core of the secondary coil of the transformer, and by locally magnetically saturating the iron core in this part, the
In addition to lowering the effective value of the secondary voltage, the discharge lamp F ₁ ,
It is designed to obtain a peak value sufficient for F ₂ starting, and to reduce the effective value Vo ₂ of the secondary voltage during no-load conditions. In addition, the starting compensation capacitor C ₀
has high impedance, and discharge lamps
It is connected in parallel to F ₁ and is activated during starting.

Now, there is no-load secondary voltage across discharge lamps F ₁ and F ₂ .
When Vo ₂ is applied, voltage Vo ₂ is applied to the discharge lamp F ₁ via the starting compensation capacitor C ₀ , and the discharge lamp F ₂ starts to slightly discharge. As the slight discharge progresses, the current gradually increases, and since the starting compensation capacitor _C0 has high impedance, the voltage across it increases. Therefore, the discharge lamps F ₁ and F ₂₁ start slight discharge, and both discharge lamps F ₁ and F ₂ shift to main discharge, and the two lamps are lit almost simultaneously. Since this lead peak type ballast T can light two lamps with the starting voltage for one lamp, it can be made compact.For example, in a 40W fluorescent lamp, the no-load secondary voltage Vo ₂ is about 290V. However,
In this case, since _the discharge lamps F ₁ and F ₂ are connected in series, it is not possible to light up only one of the discharge lamps F ₁ and F ₂ .
There was a problem in that when F ₂ reached the end of its lifespan and ceased to be lit, the other discharge lamps F ₁ and F ₂ also became unlit.

[Object of the Invention] The present invention has been made in view of the above points, and its purpose is to automatically turn on one discharge lamp even if the other discharge lamp stops lighting. To provide a discharge lamp lighting device which is simple in structure and low in cost.

[Disclosure of the Invention] (Structure) The present invention comprises a lighting circuit in which two discharge lamps are connected in series and an AC power source is applied to both ends thereof through a current limiting element, and a series circuit including a switch element and an impedance element. are connected in parallel to each discharge lamp to form a first and second bypass circuit section, and detect a non-lighting state of any one of the above-mentioned discharge lamps and release the non-lighting state when the non-lighting state is detected. It consists of a fault detection unit that closes the switch element of the bypass circuit unit connected in parallel to the electric lamp, and by making the switch element or impedance element of both bypass circuit units common, it is possible to prevent one of the discharge lamps from lighting up. To provide a discharge lamp lighting device which can automatically light up the other discharge lamp even when the other discharge lamp is turned on, has a simple circuit configuration and is low in cost.

Embodiment 1 FIG. 1 shows an embodiment of the present invention, in which two discharge lamps F ₁ and F ₂ are connected in series and connected to an AC power source via an inductance element Z ₀ as a current limiting element at both ends.
V _AC is applied to form a lighting circuit, and both discharge lamps F ₁ ,
Two impedance elements Z ₁ in the series circuit of F ₂ ,
A bypass circuit section (indicated by an imaginary line in the figure) is formed by connecting Z ₂ series circuits in parallel and connecting a switch S ₁ between the connection points of these two series circuits.
That is, a series circuit of impedance element Z ₁ and switch S ₁ forms a first bypass circuit for discharge lamp F ₁ , and a series circuit of impedance element Z ₂ and switch S ₂₁ forms a first bypass circuit for discharge lamp F ₂₂ . 2
A bypass circuit section is formed, and switch S ₁
is a common switch element for both bypass circuit sections. On the other hand, the fault detection unit A detects discharge lamps F ₁ and F ₂
Either discharge lamp based on the voltage across the series circuit of
It is designed to detect that F ₁ and F ₂ are in the non-lighting state, and when the non-lighting state is detected, the non-lighting state is turned off by closing the switch S ₁ common to both bypass circuit sections. Bypass circuit sections corresponding to the discharge lamps F ₁ and F ₂ are operated. Here, the impedance elements Z ₁ and Z ₂ have an impedance that allows one lamp to be lit at its rated value. In addition, the malfunction detection unit A does not close the switch S 1 at the voltage Vf ₁ +Vf ₂ at both ends when the discharge lamps F ₁ and F ₂ are normally lit, and does not close the switch S ₁ when the discharge lamps F 1 and F ₂ are normally lit.
At the voltage Vf ₁ +Vf ₂ at both ends when F ₂ is turned off, the switch S ₁ is closed.

Now, when the discharge lamp F ₁ reaches the end of its life and stops lighting, the voltage between terminals e and f becomes Vz ₁ + Vz ₂ ,
Higher than Vf ₁ + Vf ₂ . Therefore, the malfunction detection section A determines that either of the discharge lamps F ₁ and F ₂ is in the non-lighting state and closes the switch S ₁ . By closing this switch S ₁ , the discharge lamp F ₁
energized through impedance element Z ₁ and switch S ₁ , and discharge lamp F ₁ is automatically lit at its rated value. Here, if switch _S1 is a switch with a holding function, even if only discharge lamp _F1 is turned on and the voltage between e and f drops below the above-mentioned _Vz1 + _Vz2 , switch _S1 will close. Therefore, the single lamp rated lighting state continues, and an unstable lighting state can be avoided. In this case, when the discharge lamp _F1 is replaced, two lamps can be lit by resetting the switch _S1 .

On the other hand, if discharge lamp F ₁ stops lighting up,
Needless to say, electricity is supplied to the discharge lamp F ₁ via the second bypass circuit section, and the discharge lamp F ₁ automatically lights up at the rated value. Furthermore, in the embodiment, the switch _S1 is common to both bypass circuit sections, so the circuit configuration is simplified and costs can be reduced.

Embodiment 2 FIG. 2 shows another embodiment, in which discharge lamps F ₁ ,
By connecting the series circuit of switches S ₁ and S ₂ in parallel to the series circuit of F ₂ and connecting the impedance element Z ₁ between the connection points of both series circuits, the switch S ₁ and the impedance element Z ₁ can dissipate. A first bypass circuit section for the electric lamp F ₁ is formed, a second bypass circuit section for the discharge lamp F ₁ is formed by the switch S ₂ and an impedance element Z ₁ , and the impedance element Z ₁ is common to both bypass circuit sections. The two fault detection units A ₁ and A ₂ are connected to the discharge lamps F ₁ and F ₂ respectively.
are connected in parallel to each other, and these malfunction detectors A _{1 and} A ₂ detect the non-lighting state based on the voltage across each discharge lamp F ₁ and _{F 2 .} The switch elements S ₁ and S ₂ of the bypass circuit section connected in parallel to the discharge lamps F ₁ and F ₂ in the state are closed.

Now, for example, if the discharge lamp _F1 stops lighting and the detection voltage of the malfunction detection part _A1 increases, the discharge lamp
The non-lighting state of F ₁ is detected, the switch S ₁ is closed, the discharge lamp F ₁ is energized through the bypass circuit section consisting of the switch S ₁ and the impedance element Z ₁ , and the discharge lamp F ₁ is automatically switched to the rated value. It is about to be lit. Furthermore, when the malfunction detection unit A ₂ detects that the discharge lamp F ₁ has stopped lighting, the switch S ₂ is similarly closed and the discharge lamp is turned off.
F ₁ is automatically turned on.
Furthermore, since the impedance element is common to both bypass circuit sections, the circuit configuration is simplified and costs can be reduced.

[Effects of the Invention] As described above, the present invention provides a lighting circuit in which two discharge lamps are connected in series and AC power is applied to both ends thereof through a current limiting element, and a series circuit including a switch element and an impedance element. are connected in parallel to each discharge lamp to form a first and second bypass circuit section, and detect a non-lighting state of any one of the above-mentioned discharge lamps and release the non-lighting state when the non-lighting state is detected. It consists of a fault detection unit that closes the switch element of the bypass circuit unit connected in parallel to the electric lamp, and since the switch element or impedance element of both bypass circuit units is common, one discharge lamp will not reach the end of its life. Even if one discharge lamp stops lighting, the other discharge lamp can be automatically turned on. Furthermore, since both bypass circuits use the same switch element or impedance element, the circuit configuration is simple. This has the effect of providing a low-cost discharge lamp lighting device.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of one embodiment of the present invention, FIG. 2 is a block circuit diagram of another embodiment, and FIG. 3 is a circuit diagram of a conventional example. F ₁ , F ₂ are discharge lamps, L ₀ is an inductance element,
V _AC is an AC power supply, S ₁ and S ₂ are switches, Z ₁ and Z ₂ are impedance elements, and A, A ₁ and A ₂ are defect detection sections.

Claims (1)

[Claims] 1. A lighting circuit in which two discharge lamps are connected in series and AC power is applied to both ends through a current limiting element, and a series circuit consisting of a switch element and an impedance element is connected in parallel to each discharge lamp. First and second bypass circuit sections, and a switch element of the bypass circuit section that detects the non-lighting state of any one of the above-mentioned discharge lamps and is connected in parallel to the discharge lamp that is in the non-lighting state when the non-lighting state is detected. 1. A discharge lamp lighting device comprising: a fault detection section for closing a discharge lamp, and a switch element or an impedance element used in both bypass circuit sections.