JPS6116496A - Device for firing discharge lamp - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge lamp lighting device in which a discharge lamp is lit by the oscillation output of an inverter circuit, and in particular to an improvement of a discharge lamp lighting device using a one-stone inverter circuit with one transistor as the inverter circuit. Regarding.

2. Description of the Related Art Inverter circuits used in this type of discharge lamp lighting device include a single transistor inverter circuit with one transistor and a two transistor inverter circuit with two transistors. FIG. 8 shows the overall circuit of a discharge lamp lighting device using a -stone inverter circuit.

In the figure, 1 is a rectifier circuit, 2 is a single-stone inverter circuit, and 8 is a discharge lamp lighting circuit. The lighting operation of this device is well known and is generally as follows. First, when a switch (not shown) is turned on, a base current flows into the transistor Tr of the inverter circuit 2 through the starting resistor R8, and thereby the inverter circuit 2 starts oscillating. Then, a high frequency voltage is generated in the oscillation transformer T1, which is a component of the inverter circuit 2, and this voltage is applied to the discharge lamp through the current limiting means 2, thereby lighting the discharge lamp.

Problems to be Solved by the Invention By the way, in the above-mentioned -6 inverter circuit,
There is a problem in that when starting resistors R and S have a small value of 50Ω or less, sufficient base current flows through the transistor, and as a result, the efficiency given by the ratio of input power to lamp power deteriorates. In addition, since the power loss in the starting resistor is large, the starting resistor becomes hot, and depending on the model, thermal countermeasures may become a problem.

On the other hand, the two-stone inverter circuit does not have the above-mentioned problems and problems and has the advantage of extremely high efficiency, but on the other hand, it requires two transistors, making it expensive.

Means for Solving the Problems The present invention has these points in mind, and although it uses a -6 inverter circuit, it has low circuit loss and high efficiency.
The present invention provides an extremely useful discharge lamp lighting device that is not as expensive as the case where a two-wheel inverter circuit is used.

That is, the discharge lamp lighting device according to the present invention includes a rectifier circuit, a −6 inverter circuit connected to the output side of the rectifier circuit, including an oscillation transformer, and having one transistor, and a −6 inverter circuit connected to the output side of the inverter circuit. discharge lamp lighting circuit and wl
A switching means that becomes conductive only immediately after the power is turned on to drive the inverter circuit, and a switching means that is energized based on the oscillation operation of the inverter circuit to generate a drive voltage, and feeds the drive voltage back to the inverter circuit to maintain the oscillation of the inverter circuit. The gist is that the oscillation sustaining means is comprised of oscillation maintaining means.

Operation of the invention When the power source is turned on, the switching means becomes conductive for a short time immediately after that, drives the inverter circuit, and starts oscillation. Once the inverter circuit starts oscillating, the oscillation maintaining means maintains the oscillation operation of the inverter circuit. The oscillation sustaining means is energized based on the oscillation operation of the inverter circuit to generate a drive voltage, which is fed back to the inverter circuit to maintain oscillation. Therefore, once the inverter circuit oscillates, it can maintain oscillation using part of its own generated energy, without having to receive base current from the power supply through a starting resistor like in the conventional -6 inverter circuit. can. As a result, a significant reduction in circuit loss can be expected.

Embodiment FIG. 1 shows the overall circuit of a discharge lamp lighting device as an embodiment of the present invention. Note that the same reference numerals are given to the circuits, components, and parts in FIG. 8.

In the figure, 4 is a switching means, and 5 is an oscillation maintaining means.

In this embodiment, the switching means 4 consists of one transistor Tr2, a diode DB and an electrolytic capacitor C2 inserted in series with its base circuit. The operation of this switching means 4 is as follows. First, when the power is turned on, a DC voltage is generated between the output terminals A and B of the rectifier circuit 1, with the A side having a positive potential. This DC voltage causes a charging current IC to flow through the electrolytic capacitor C2, causing a base current to flow through the transistor Tr2. As a result, the transistor Tr2 becomes conductive. When the transistor T r 2 becomes conductive, a base current flows from the point A to the transistor Tri of the inverter circuit 2 through the Tr 2 and the drive coil 12, and the inverter circuit 2 starts an oscillation operation.

On the other hand, the electrolytic capacitor C2 begins to be charged as a charging current flows through the capacitor C2.

The charging time constant is set to a small value J: to reduce the capacitance and series resistance of the electrolytic capacitor.
Capacitor C2 immediately reaches the saturation voltage as shown in FIG. 2(a). Then, the base current stops flowing and the transistor Tr2 turns non-conductive. At this time, capacitor C2 is charged to the polarity shown, and diode D
Due to the opposite polarity of B and the non-conduction of transistors T and r2, the discharge resistance is reduced, so that the charge stored in the capacitor C2 is not easily discharged.

Therefore, as shown in FIG. 2(b), the transistor Tr2 is conductive for a short period of time immediately after the power is turned on, and IJ is not conductive during the subsequent inverter oscillation period. Additionally, according to experiments, even if the diode D8 is not present, the switching means 4'1
There was no problem with B production.

Next, in this embodiment, the oscillation maintaining means 5 includes a feedback winding 13 wound around the oscillation transformer T1, a diode D4, and a
It consists of an α-resolving capacitor c8. The operation of the oscillator W holding means 5 is as follows.

When the impark circuit 2 is oscillating, a voltage is induced in the feedback winding 18 based on the oscillation of the inverter circuit I@2. This induced voltage is a high-frequency alternating voltage, but
It is half-wave rectified at D4 and charged into an electrolytic capacitor C3. In this case, if the number of turns of the feedback winding 18 is appropriately selected to store sufficient charge in the capacitor c8, this charge will be discharged through the drive coil 12 and the transistor Tri
! The ζ base current is passed to maintain the oscillation of the inverter circuit 2. Therefore, the inverter circuit is driven through the switching means 4 and starts oscillating at the moment the power is turned on, but once it has oscillated, a part of the oscillation output is fed back through the oscillation maintaining means 5 to maintain the oscillation. It is. The operation of lighting the discharge lamp by the oscillation of the inverter circuit 2 is the same as that of the conventional one, so the explanation will be omitted.

Effects of the Invention Since the discharge lamp lighting device according to the present invention is configured as described above, the power supplied from the power source to the inverter circuit through the switching means is only for a short period of time immediately after the power is turned on, and thereafter is supplied to the inverter circuit by the oscillation maintaining means. Oscillation can be maintained by a clever technique with low circuit loss in which a portion of the oscillation output of the inverter circuit is fed back, resulting in a significant improvement in the efficiency of the device (lamp power/input power). According to actual measurements, the conventional device using a -stone inverter circuit has a power of 88.
While the efficiency was 8%, the device of the present invention had a high efficiency of 91.76%. This high efficiency is comparable to that of a device using a two-part inverter circuit. In addition, unlike conventional devices, the device of the present invention does not have a starting resistor, which eliminates the problem caused by the heat generated by the resistor, and since the device of the present invention partially uses an inverter circuit, It also has the effect of being able to be configured at a low cost.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the entire circuit of a discharge lamp lighting device as an embodiment of the present invention, Fig. 2 is a waveform diagram for explaining the operation of the circuit of Fig. 1, and Fig. 8 is a diagram showing the conventional device. FIG. 1... rectifier circuit, 2...-stone inverter circuit, 8.
...Discharge lamp lighting circuit, 4...Switching means, 5.
...Oscillation maintenance means.

Claims (2)

[Claims] (1) A rectifier circuit, a single-transistor inverter circuit connected to the output side of the rectifier circuit, including an oscillation transformer, and having one transistor, and a discharge lamp lighting circuit provided on the output side of the inverter circuit, and turning on the power. a switching means that is turned on only immediately after to drive the inverter circuit; and an oscillation means that is energized based on the oscillation operation of the inverter circuit to generate a drive voltage, and that feeds back the drive voltage to the inverter circuit to maintain the oscillation of the inverter circuit. A discharge lamp lighting device comprising: a maintenance means. (2) The discharge lamp lighting according to claim 1, characterized in that the oscillation maintaining means is constituted by a series circuit of a feedback winding wound around an oscillation transformer, a rectifying means, and a capacitor. Device.