JPS59130087A - 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 so-called sequential start type discharge lamp lighting device, which is a simple device that achieves all at once the improvement of starting performance and discharge lamp life, and the protection of the lighting circuit at the end of the discharge lamp life. provides a flexible configuration.

FIG. 1 shows an example of a conventional sequential start type discharge lamp lighting device, in which the secondary winding 3 of a leakage type output transformer 3 of an inverter 2 for generating high frequency output supplied from a commercial power source 1 is shown.
Connect a series circuit of 4.5 discharge lamps to a, and connect each discharge lamp 4.5
A capacitor 6 for sequential starting is connected in parallel with one of the discharge lamps 4 on the left side, where the filament is connected to the preheating tap of the secondary winding 3a.

The operation of such a discharge lamp lighting device is as follows (as is known, first, the secondary voltage of the output transformer 3 or the capacitor 6
The secondary voltage is applied to the other discharge lamp 4 through the slightly discharged discharge lamp 5, causing a slight discharge, and this discharge lamp 4 also causes a slight discharge. However, both lamps can be started and lit normally, and the voltage transmission effect of the capacitor 6 allows a plurality of discharge lamps 4.5 connected in series to be started one after another at a low secondary voltage.

However, in such a device, there is a risk that the discharge lamp may start before the filament is sufficiently preheated, resulting in a so-called cold start, which may shorten the service life. In particular, the life of the discharge lamp 5 that is started first is significantly shortened.

Furthermore, it is known that at the end of its life, a discharge lamp enters a so-called half-wave discharge state in which it discharges only in one direction, but if the discharge lamp 4 on the side to which the capacitor 6 is connected in parallel reaches a half-wave discharge state, Since the capacitor 6 cannot pass a direct current, a direct current due to the half-wave discharge of the discharge lamp 4 flows throughout the circuit, and the temperature of the output transformer 3 becomes abnormally high.

This is true even when a single choke is used instead of a single cage type output transformer.

Furthermore, in the case of high frequency lighting using the inverter 2 as in the above example, the impedance of the capacitor 6 under the high frequency becomes small, and a considerable current flows through the capacitor 6 even during lighting, causing light to flow between the discharge lamps 4 and 5. There is a drawback that the output becomes unbalanced, which affects the life of the discharge lamp 4.5 and makes it unsightly.

The present invention has been made in view of these drawbacks, and will be described below based on embodiments shown in the drawings.

Figures 2 to 4s4 show an embodiment of the present invention.
In place of the conventional tertiary starting type capacitor 6, a secondary winding 7a of a magnetic switch 7 called a bottle cushion is connected.

As shown in Fig. 3, the characteristics of the magnetic switch 7 are as follows: When the current signal (■) of XSY between the primary terminals is small, the secondary winding 7a has a very large inductance L, and the current signal (■) becomes thick The secondary winding 7a is saturated and almost short-circuited.

In this embodiment, a current signal 2 as shown in FIG. 4 is applied between the primary side terminals X and Y of the magnetic switch 7. That is, the current signal I is not applied for a predetermined time T after the power is turned on. During this time, since the inverter 2 is oscillating, either sufficient preheating current is supplied to the filaments of each discharge lamp 4.5, or the inductance L of the secondary winding 7a is sufficiently large, so the discharge lamp 5 cannot be started due to insufficient voltage. is not enough. After the predetermined time T has elapsed, the current signal l is generated.

When the voltage is applied, the secondary winding 1ava of the magnetic switch 70 becomes saturated and almost short-circuited, the secondary voltage of the output lance 3 is applied to the discharge lamp 5, the discharge lamp 5 is slightly discharged, and then this slightly discharged discharge lamp 5 A secondary voltage is applied to the other discharge lamp 4 through the discharge lamp 4, which also causes a slight discharge, and the series circuit of discharge lamps 4 and 5 maintains normal lighting from the start. After the time t2, the current signal I of the magnetic switch 7 becomes I(), and the inductance L of the secondary winding 7a becomes sufficiently large, so that almost no current flows, and the magnetic switch 7 becomes substantially disconnected from the circuit.

When one of the discharge lamps 4 reaches the end of its life and a half-wave discharge phenomenon occurs, the impedance of the secondary winding 7a of the magnetic switch 7 is almost the only factor against the remaining reverse half-wave direct current. Output transformer 3 is used to make the current flow
The output current is an alternating current that is a combination of these, and the temperature will not rise abnormally. This is the output 3
The same is true if a single choke is used without a choke.

In particular, in this embodiment, since the discharge lamp 4.5 is lit at a high frequency, the impedance of the secondary winding 7a of the magnetic switch 7 becomes even larger due to the high lighting frequency.
Compared to the conventional method using a capacitor 6, the imbalance in light output between the discharge lamps 4 and 5 during lighting can be much suppressed.

In this embodiment, the magnetic switch 7 is turned on for a predetermined time T after a predetermined time T has elapsed after the power is turned on, so that the discharge lamp 4.5 is preheated prior to applying the starting voltage to the discharge lamp 4.5. It goes without saying that the effects of the present invention will not be lost even if the power is turned on for a predetermined period of time T immediately after the power is turned on, in order to further improve the lifespan of 4.5.

As described above, the present invention connects a series circuit of discharge lamps to both ends of an AC power supply through an inductive element, and connects a secondary winding of a magnetic switch in parallel with at least one of the discharge lamps. Since a current signal is applied to the primary winding of the magnetic switch for a predetermined period of time after the power is turned on, the simple structure improves starting performance and the life of the discharge lamp, and at the same time prevents circuit abnormalities during half-wave discharge of the discharge lamp. We were able to provide the following.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a conventional example, Fig. 2 is a circuit diagram showing an embodiment of the present invention, Fig. 3 is a characteristic diagram of a magnetic switch, and Fig. 4 is a circuit diagram showing an example of the present invention.
The figure is a diagram showing a current signal of a magnetic switch. 1...Commercial power supply, 2...High frequency inverter, 3...
・Output lamp, 4.5...Discharge lamp, 7...Magnetic switch Patent applicant Matsushita Electric Works Co., Ltd. Patent attorney Toshimaru Takemoto (and 2 others)

Claims (2)

[Claims] (1) A series circuit of discharge lamps is connected to both ends of the AC power supply via at least an inductive element, and a secondary winding of a magnetic switch is connected in parallel with at least one of the discharge lamps, and the primary winding of the magnetic switch is A discharge lamp lighting device characterized in that a current signal is applied to a line for a predetermined period of time after power is turned on. (2) The discharge lamp lighting device according to claim 1, wherein the AC power source is a high frequency power source including a high frequency inverter.