JPS6231995A - Discharge lamp dual bright point 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 (Field of Industrial Application) The present invention relates to a lighting device that uses a voltage doubler rectifier to generate two bright spots on a filament of a discharge lamp to light the lamp.

(Prior Art) In this type of device, a first switch element and one filament of a discharge lamp are connected between the output terminals of a DC power supply device consisting of an AC power supply and a voltage doubler rectifier using the AC power supply as an input power supply. and a second switch element, as well as a third switch element.
A series circuit of the switch element, the other filament of the discharge lamp, and a fourth switch element is connected, and the first and fourth switch elements are periodically turned on and off in conjunction with each other. The third and second switch elements are turned on and off in conjunction with each other in a phase opposite to the off state, and when preheating of the filament is required, a secondary coil of a preheating transformer is connected to each filament. This has already been disclosed in Japanese Patent Publication No. 57-35551.

This allows the discharge lamp to be lit with direct current, increasing luminous efficiency, and eliminates the need for ballasts such as choke coils and leakage transformers, which are required when lighting with alternating current. Benefits can be obtained.

However, in this configuration, if the filament is to be heated even while the discharge lamp is on, it is sufficient to connect the secondary coil of the heating transformer in parallel to the filament as described above. The impedance is extremely small compared to .

Therefore, most of the current from the DC power source flows through the secondary coil, so that the bright spots that should be generated on the filament are concentrated only at one end of the filament. Therefore, this will prevent the generation of two bright spots.

(Problems to be Solved by the Invention) An object of the present invention is to make it possible to generate two bright spots even when a secondary coil of a heating transformer is connected in parallel to the filament.

(Means for solving the problem) This invention connects a diode in series to a circuit connecting the filament and the secondary coil of a heating transformer, so that the DC current flowing from the DC power source to the filament is directed to the secondary coil. The diode is used to prevent this.

(Example) This invention will be explained with reference to the drawings. FIG. 1 shows the basic circuit of this invention, where 1 is a discharge lamp, 2 is a DC power supply device, and here it is composed of an AC power supply (commercial AC power supply) 3 and a voltage doubler rectifier 4. . The voltage doubler rectifier 4 shown in the figure is constructed from a capacitor 5.6 and a diode 7.8.

11.12 are switch elements that are turned on and off in conjunction with each other; 13 and 14 are also switch elements that are turned on and off in conjunction with each other in opposite phases to the switch element 11.12; When turned on, switch element 13.14 is turned off and switch element 1
When 1.12 is turned off, switch element 13.14
is now turned on. These on and off cycles are repeated periodically.

A switch element 11.14 is located at each end a, a' of one filament 1a of the discharge lamp 1, and a switch element 13.1
2 is connected to each end of the other filament 1b. The series circuit of the switch i elements 1, 1, the filament 1a, and the switch element 14 and the series circuit of the switch element 13, the filament 1b, and the switch element 12 are connected in parallel to the output end of the DC power supply 2. Note that 15 is an impedance element for current limiting that is connected as necessary.

In the above configuration, switch elements 11 and 12 are turned on,
When switch element 13.14 is off, DC power supply 2
The output voltage of is applied between one end a of the filament 1a and one end b' of the other filament 1b. Also switch elements 11 and 12 are off, switch element 1
3. When 14 is on, the output voltage is equal to filament 1
b and the other end of filament 1a a'
applied between.

Here, if the output voltage is equal to or higher than the discharge starting voltage of the discharge lamp 1, the application to the discharge lamp 1 as described above will start discharging and lighting the lamp. When the switch element is repeatedly turned on and off even after lighting, when the switch element 11.12 is on and the switch element 13.14 is off, a discharge occurs between the ends a and b', and the end a
, b', a bright spot appears.

Also switch elements 11 and 12 are off, switch element 13
．． When 14 is on, a discharge occurs between the ends A and A', and a bright spot appears at the ends A and A', contrary to the previous case. As a result of the above, when the switch element is repeatedly turned on and off, the position where the bright spot is formed changes periodically according to the repetition period.

When it is necessary to heat each filament, a heating transformer 16 is prepared, its primary coil 17 is connected to the AC power source 3, and the secondary coils 18 and 19 are connected across each filament. However, such a secondary coil 18.19
is filament la.

The impedance is lower than that of 1b. Therefore, the current from the DC power supply 2 flows to the secondary coil, so
The positions where bright spots are formed on the filament are always limited to the ends a' and b'. In this case, the intention of forming two bright spots cannot be achieved. This is as described above.

Therefore, in the present invention, diodes 20 and 21 are connected in series with the secondary coils 18 and 19 so that the forward direction thereof is directed toward the positive terminal A of the DC power supply 2.

With this configuration, when the switch element 11 is turned on, the direct current that is about to go to the filament 1a via the switch element 11 is directed to the end a' via the secondary coil 18 due to the diode 20. is prevented from going to As a result, no bright spot is formed at the end a' at this time.

Similarly, when the switch element 13 is turned on, no current flows from the secondary coil 19 towards the end b' due to the diode 21, so that no bright spot is formed at the end b'. There isn't.

On the other hand, if the diodes 20 and 21 are connected as described above, one of the filaments serving as the cathode will be heated during lighting.

That is, when the switch element 11 is turned on,
Filament 1b acts as a cathode. At this time, if the secondary coil 19 is wound so that its lower side (the end facing the output terminal A of the DC power supply 2) becomes the positive pole as shown in the figure, then the secondary coil 19 Based on the induced voltage in the coil 19, a current flows through the diode 21 and into the filament 1b. This causes the filament 1b to be heated.

Similarly, when the switch element 13 is turned on, the filament 1a becomes the cathode, and at this time the secondary coil 1
Since the polarity of the induced voltage of 8 is reversed, the secondary coil 18 is located on the lower side (the end facing the output end A of the DC power supply 2).
If the filament 1a is wound so as to have a positive polarity, a current flows to the filament 1a via the diode 20 based on the induced voltage of the secondary coil 18. This causes the filament 1a to be heated.

FIG. 2 shows a specific configuration in which switch elements made of semiconductor elements are used as each of the switch elements 11 to 14. In this configuration, each switch element is turned on and off in synchronization with the AC power supply 3. For that purpose, AC power supply 3
A transformer 24 whose power source is
The switching elements 11 to 14, which are semiconductor switches such as transistors (or controlled rectifiers, etc.), are turned on and off by the secondary voltage induced in the transistors 5 to 28.

That is, secondary coils 25, 27 which induce a secondary voltage of the polarity shown are connected to the switch element 11, 12 to turn them on and off, and a secondary coil 26 which induces a secondary voltage of the opposite polarity. .28 to switch elements 13.14 to turn them on and off. The illustrated embodiment shows an example in which the transformer 24 is used also as the transformer 16 in FIG.

Note that the present invention is also applied to a lighting device for multiple lamps in which a plurality of discharge lamps are connected in series. Further, although the voltage doubler rectifier in the figure is a double voltage rectifier, it goes without saying that this may be a triple or more voltage doubler rectifier.

(Effects of the Invention) As detailed above, according to the present invention, in a configuration in which a discharge lamp is lit so as to form two bright spots on a filament using a voltage doubler rectifier as a lighting power source, each When heating the filament, even if a heating coil is connected in parallel to the filament, two bright spots can be reliably formed.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the basic configuration of the invention, and FIG. 2 is a circuit diagram showing an embodiment of the invention. DESCRIPTION OF SYMBOLS 1... Discharge lamp, 2... DC power supply device, 3... AC power supply, 4... Voltage doubler rectifier, 11-14... Switch element, 16-Transformer, 18.19-Secondary coil,
20°21...diode,

Claims (1)

[Claims] A series circuit of a first switch element, one filament of a discharge lamp, and a second switch element is installed between the output ends of a DC power supply device consisting of an AC power supply and a voltage doubler rectifier using the AC power supply as an input power supply. , and a series circuit of a third switch element, the other filament of the discharge lamp, and a fourth switch element is connected, and the first and fourth switch elements are periodically turned on and off in conjunction with each other. , in a discharge lamp two-bright spot lighting device that turns on and off the third and second switch elements in an opposite phase to the on and off states, in each of the series circuits, in parallel with each of the filaments; Coils for filament heating are connected in parallel, and diodes are connected in series with each of the coils in a forward direction toward the positive output end of the DC power supply, and the positive side of each coil is A two-point lighting device for a discharge lamp, wherein each of the coils is excited in synchronization with the on/off period of the switch element so that the induced voltage at the end facing the output end has opposite polarity.