JPS61243696A - Discharge lamp lighting apparatus - 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 [Technical Field] The present invention relates to a discharge lamp lighting device that has a plurality of discharge paths and sequentially switches the discharge paths to achieve one function.

[Background Art] The present inventor previously proposed a discharge lamp as described above (VtMBH58-+ No. 31593). FIG. 5 shows an example of such a discharge lamp, in which the discharge space airtightly formed by the outer bulb 1 and the stem 2 is bent in an LJ shape, and red, green, and blue light is emitted on the inner surface. Three inner tubes 3R, 3G, and 3B coated with a phosphor having a phosphor are disposed, and the inner tube 3R.

One end of each of 3G and 3B is airtightly fixed by lath welding of the anode 4, and the other end is opened near the cathode 5 coated with an electron radioactive material.

Furthermore, several rorr of rare gas and a small amount of mercury are sealed inside the outer tube 1.

Figure 6 is a circuit diagram showing the basic configuration for lighting a discharge lamp, in which a closed circuit is configured with a DC power source Vs, a discharge path changeover switch SW, and a current limiting resistor R. By controlling the switch sw, each inner tube 3R
, 3G, and 3B, and the luminescent color is controlled by changing the mutual luminescence time ratio. For example, the seventh
As shown in the figure, three arc tubes emit red, green, and blue light within a constant period T of about 10+ns, namely inner tubes 3R and 3G.
, 3B, and by changing their mutual ratio, each arc tube appears to be emitting light at the same time with the intensity of the set ratio, and in the same figure, the new t2
and t3, they emit white, yellow, and purple light, allowing for variable color control.

However, in such a discharge lamp lighting device, when switching the discharge path, an instantaneous current pause or decrease period occurs, and in order to realize stable switching lighting operation, the power supply voltage must be made sufficiently large relative to the lamp voltage. According to experiments, a power supply voltage of 5 to 7 times the lamp voltage was required. Therefore, the power loss in the current limiting resistor R becomes extremely large, and the circuit efficiency becomes extremely low.

Therefore, the following method can be considered to improve this problem. Figure 8 shows the basic configuration of such a system, which includes a DC power supply Vs, a discharge path changeover switch SW1
A discharge lamp PL having a plurality of discharge paths and an impedance consisting of a resistor R and an inductance 1- are connected in series to form a closed circuit.

FIG. 9 shows the circuit diagram, in which the discharge path changeover switch SW is connected to three transistors Tr1yTr2. Tr
3, and each transistor Tr+ r T
A control circuit C controls r2+T r3.

In addition, the power supply Vs is a control power supply Vs, and a main circuit power supply ■S.
2, each of the above transistors Tr+y
Tr2yTr3 constitute a switch means.

With this configuration, if the current tries to decrease at the moment when the discharge path is switched (for example, the moment when the inner tube 3R7'l-, which emits red light, is switched to the inner tube 3G, which emits green light), the series Connected inductance1.
Ki to 4? A voltage is generated and applied to the discharge lamp FL superimposed on the power supply voltage. Therefore, the tube voltage ■0. (Discharge lamp Fl
, and each transistor Tr, , Tr2 . As shown in FIG. 10(d), the voltage across the series circuit of T r3 generates a pulse-like high voltage every time the discharge path is switched. still,
10(8) to (c) show the state in which each transistor Trr2wTr+ is turned on in a time-division manner by the control circuit C, and FIG. 10(a) shows the transistor Tr, (red ), the same figure (b) shows the transistor T
r2 (green), and (e) of the same figure shows the state of the transistor Tr3 (blue).

In this way, the necessary high voltage is supplied by the inductance at the moment the discharge path is switched, so that sufficiently stable operation can be maintained by making the power supply voltage slightly higher than the effective value of the tube voltage. According to experiments, it was possible to reduce the required power supply voltage to less than twice the tube voltage. with this,
Although the power supply voltage has been reduced, a high-voltage pulse is still required at the moment of switching the discharge path, and the transistors Tr+4r2 and Tr3 do not have enough withstand voltage to withstand such a high-voltage pulse. However, using such expensive transistors posed a major problem in terms of circuit cost.

[Objective of the Invention 1] The present invention has been provided in view of the above-mentioned problems, and by reducing the high voltage pulse required when switching the discharge path, the withstand voltage required for the switching transistor is lowered, and the circuit is lowered. The present invention provides a discharge lamp lighting device aimed at reducing costs.

EDisclosure of the Invention 1 (Structure) The present invention provides a preheating current supply means for flowing a pulsed preheating current to the discharge path when switching the discharge path, and the preheating current supply means preheats the discharge path when switching the discharge path. It is characterized by allowing current to flow through it.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

By the way, it is generally known that if the electrodes of a discharge lamp (fluorescent lamp) are heated in advance, the discharge lamp can be started or restarted with a relatively low applied voltage. The present invention utilizes such characteristics to reduce the high voltage pulse required when switching the discharge path. By the way, in the conventional example (FIGS. 9 and 10), when the discharge path is switched, the current is 1± momentarily, but the lamp current, that is, the single portion flowing to the common cathode becomes zero once. This is one of the reasons why the applied pulse required for switching the discharge path is increased. Therefore,
The present invention supplies a preheating current to the common cathode when switching the discharge path, thereby reducing the high voltage pulse required for switching.

That is, FIG. 1 shows a circuit diagram of an embodiment of the present invention, and the basic configuration of this embodiment is the same as that of FIG. The collector of this transistor Tr< is connected to the discharge lamp F.
It is connected to the non-power side of the common cathode 5 of M- via a resistor r. The transistor Tr4 and the resistor r constitute a preheating current supply means.

The operation will be explained below with reference to FIG. FIG. 2 shows four transistors TrHTr2. T+3. A time chart showing on and off of Tr4 is shown. In the conventional example (Fig. 10), three transistors are repeatedly turned on and off in sequence, such as transistor Trl → transistor Tr2 → transistor Tr, → transistor Tr. On the other hand, in the present invention, transistor Tr1→transistor Tr
, → Transistor Tr2 → Transistor 'f'r, → Transistor Tr, → Transistor Tr, → Transistor Tr, the three transistors T r , T r
2 y T r: Transi X j' when switching l
T r 4 is turned on for a relatively short period of time (or in a pulsed manner) to cause a preheating current to flow through the common cathode 5 .

That is, the drop in the current flowing through the common cathode 5 when switching the discharge path is compensated for by supplying a preheating current through the transistor Tr, and the same effect as when a preheating current is constantly flowing through the common cathode 5 is obtained. It has gained. As a result, the high voltage pulse required when switching the discharge path is reduced, and the withstand voltage required for the transistors 1r and Tr3 is also reduced. In this way, by supplying a current equivalent to the preheating current to the common cathode 5 for a short period of time before and after switching the discharge path, and eliminating the period when the current flowing through the common cathode ff15 becomes zero, the high voltage pulse required when switching the discharge path can be reduced. and transistor Tr, ~1'
The withstand voltage required for r3 can be lowered, and the cost of the lighting circuit can be reduced.

FIG. 3 shows another embodiment, and the basic configuration is almost the same as that in FIG. 1, but this embodiment is characterized by a fourth anode 6 disposed inside the discharge lamp P The collector of the transistor Tr is connected to the anode 6 via a resistor r.

The operation of this embodiment is also exactly the same as the time chart shown in FIG. 2, and during the ON period of the transistor Tr, positive
A discharge current flows between the common cathode 5 and the common cathode 5, and a current corresponding to the preheating current is supplied to the common cathode 5.
The same effect as the above embodiment is obtained.

In addition, FIG. 4 shows another embodiment of the discharge lamp Fl-, in which the inner tube 3
The open ends of R, 3G, and 3B are arranged in the opening 8 of the cathode tube 7 that covers the cathode 5, and similarly to the above, a preheating current is supplied by the transistor 1r and the resistor r at the time of discharge switching. I try to do that. Furthermore, instead of only a single discharge lamp consisting of a plurality of discharge paths, a plurality of discharge lamps may form a plurality of discharge paths.

[Effects of the Invention 1] As described above, the present invention includes a switch means for switching the discharge current flowing from a power supply to a plurality of parallel discharge paths using a switching transistor, and a control circuit for controlling this switch means in a time-division manner. -L2 Since the device is provided with a preheating current supply means that causes a pulsed preheating current to flow through the discharge path when switching the discharge path, the preheating current supply means causes the pulsed preheating current to flow when the discharge path is switched. This eliminates the period when the current flowing through the cathode of the discharge path is zero, and therefore there is no need to generate a high-voltage pulse that heats the cathode of the discharge path. It is possible to reduce the high-voltage pulse required when switching the switching transistor, thereby reducing the withstand voltage required of the switching transistor, which has the effect of reducing the cost of the lighting circuit.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of one embodiment of the present invention, Fig. 2 is a time chart of the same L, Fig. 3 is a circuit diagram of another embodiment of the same, and Fig. 4 is a circuit diagram of the same J2. 5(a) and 5(b) are perspective views and plan views of the discharge lamp, FIG. 6 is a circuit diagram of a conventional example, FIG. 7 is a time chart of the same as above, and FIG. FIG. 8 is a circuit diagram of another conventional example, FIG. 9 is a circuit diagram of the same, and FIG. 10 is a time chart of the same. 3 R, 3G, 3 B are inner tubes, 4 is an anode, 5 is a cathode, 6
is an anode, P L is a discharge lamp, C is a control circuit, Tr, ~Tr
3 indicates a switching transistor. Agent Patent attorney Stone 1) 艮 7〉 〉 ψ 〉 ``0 [A7 ′+ N- -to AQ-

Claims (1)

[Claims] (1) Switching means for switching discharge current flowing from a power source to a plurality of parallel discharge paths using a switching transistor;
A discharge lamp lighting device comprising: a control circuit for time-division control of the switch means; and a preheating current supply means for supplying a pulsed preheating current to the discharge path when switching the discharge path.