JPH09245983A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device which can reduce the consumed power to a half by sensing the primary side current fed to the primary side of a transformer of a push-pull inverter, and setting the operation of a regulator for controlling a discharge lamp concerned to the half-cycle operating point of the primary side current. SOLUTION: One end of a resistance 14 is connected with the emitter of a transistor 4 while the other end is connected with the conneting point of the emitter of another transistor 5 with the ground. When a drive signal is fed to a transistor 13 with the operation of a control circuit 12, the base currents of the transistors 4, 5 are supplied through resistances 6, 7, and either transistor (Tr) 4 or 5 is turned on. The primary side current fed to the primary side of transformer 3 with turn-on of Tr 4, 5 flows in a portion of half one cycle to a resistance 14 as a current sensing means and becomes a current having an amperage differing from cycle to cycle. The power consumed by the resistance 14 reduces to one half of the conventional value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device for lighting a discharge lamp using a push-pull inverter including a transformer, and more particularly, controlling an input current to the transformer according to a detection result of a primary side current of the transformer. The present invention relates to a discharge lamp lighting device provided with a so-called feedback type regulator for controlling the lighting state of the discharge lamp.

[0002]

2. Description of the Related Art Conventionally, a discharge lamp lighting device for lighting a so-called discharge lamp such as a cold cathode fluorescent discharge lamp or a neon discharge lamp has been known.
For example, it is useful as a backlight of a liquid crystal display panel which has been frequently used in recent years and an appropriate lighting display device, and various devices have been put to practical use. FIG. 2 is an electric circuit diagram showing an example of a conventionally known discharge lamp lighting device.
A push-pull inverter 2 composed of a transformer 3, transistors 4,5, resistors 6 and 7, a capacitor 8 and the like is used to boost the voltage to a high voltage for lighting a discharge lamp 9, and a control circuit 12 and a transistor 13 are provided to generate a current. A feedback type regulator 11 for detecting the primary side current of the transformer 3 via a resistor 10 as a detection means and controlling the input current to the transformer 3 according to the detection result to control the lighting state of the discharge lamp 9 is provided. It is an example of a discharge lamp lighting device.

In the discharge lamp lighting device of FIG. 2, when the transistor 13 is first operated by the operation of the control circuit 12, the base currents of the transistors 4 and 5 are supplied via the resistors 6 and 7, whereby One of the transistors 4 and 5 is turned on, and thereafter, the operation of the oscillation configuration including the transistors 4 and 5, the capacitor 8, the transformer 3 and the discharge lamp 9 is started, and the discharge lamp 9 is generated on the secondary side of the transformer 3. The lighting operation is started in response to the supplied high voltage.

At this time, the output currents of the transistors 4 and 5 alternately flow through the resistor 10 which is a current detecting element, that is, the currents of the positive and negative oscillation entire cycles flow, and the voltage drop caused by the currents occurs. Control circuit 12
Detected by the control circuit 12, the control circuit 12 controls the current supplied to the bases of the transistors 4 and 5 by controlling the operation of the transistor 13 according to the detected voltage value.

Controlling the current supplied to the bases of the transistors 4 and 5, that is, the so-called base current, means that the input current to the transformer 3 is controlled. The lighting operation of 9 can be controlled to a lighting state in which the lighting operation is performed with a constant brightness.
Further, since the output currents of the transistors 4 and 5 are uniform, the voltage peak values across the capacitor 8 are also positive and negative, and the boosted output of the transformer 3 is also a uniform peak voltage.

[0006]

As described above, in the conventional discharge lamp lighting device, the transformer 3 is detected based on the current detection by the resistor 10 which is the current detection means to which the currents of both positive and negative cycles are applied. The input current, that is, the current on the primary side of the transformer 3 is controlled. Therefore, the resistance 10
In addition to the inconvenience that a large amount of power is consumed and a large amount of it is lost, the influence of heat generation is also large, and a relatively large shape with a large capacity is required as the resistor 10 described above. There was a disadvantage that it would limit weight reduction.

Further, in the conventional discharge lamp lighting device,
The waveform of the output voltage output to the secondary side of the transformer 3 is a waveform in which the positive and negative peak values are equal across the ground level, in other words, the waveform in which the positive and negative region areas are equal to the ground level, and therefore the discharge lamp 9 Since a high voltage having a waveform of such a characteristic is supplied, therefore, when a neon discharge lamp is used as the discharge lamp 9, for example, there is a risk of a lighting state in which a bright and dark stripe pattern is generated.

The present invention has been made in consideration of the above disadvantages, and the power consumption by the current detecting means can be halved, so that the overall size and weight of the device can be reduced, and a neon discharge lamp can be used as a discharge lamp. An object of the present invention is to provide a discharge lamp lighting device that does not cause a lighting state in which a striped pattern is generated even when used.

[0009]

In order to solve this problem, the present invention detects a primary-side current input to a transformer of a push-pull inverter, and detects the primary-side current of a discharge lamp according to the detected primary-side current. A discharge lamp lighting device is configured by arranging a current detecting means for controlling the operation of a feedback type regulator for controlling a lighting state at a position where the primary side current flows only for half a cycle.

As a result, the power consumption by the current detecting means can be reduced, and the entire device can be reduced in size and weight. Further, the waveform of the secondary output voltage of the push-pull inverter can be obtained by measuring the area of the positive and negative regions with respect to the ground level. Since they can be distorted so as to have different waveforms, it is possible to obtain a discharge lamp lighting device that does not generate a lighting state in which a striped pattern occurs even when a neon discharge lamp is used as the discharge lamp.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a push-pull inverter including a transformer, and a positive / negative current of a primary side current having a positive / negative oscillation cycle input to the transformer. It is provided with a current detection means arranged at one of the locations where the primary side current flows, and a feedback type regulator for controlling the lighting state of the discharge lamp according to the primary side current detected by the current detection means. The discharge lamp lighting device is configured to have a function of reducing power consumption in the current detecting means and distorting the secondary side output voltage waveform of the push-pull inverter.

According to a second aspect of the present invention, a push-pull inverter including a transformer and an input current to the transformer according to a detection output of a current detecting means for detecting a primary side current input to the transformer. In a discharge lamp lighting device having a feedback type regulator for controlling the supply state of the discharge lamp to control the lighting state of the discharge lamp, the current detection means is arranged at a location where the primary side current flows for only half a cycle. A discharge lamp lighting device is configured,
It has the same operation as that of the discharge lamp lighting device according to the first aspect.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. FIG. 1 is an electric circuit diagram showing an embodiment of a discharge lamp lighting device according to the present invention.
Items having the same reference numerals as those in FIG. As is apparent from FIG. 1, the present embodiment is different from the conventional discharge lamp lighting device described above with reference to FIG. 2 and the resistor 14 which is the current detection means for detecting the primary side current input to the transformer 3. Has a similar configuration.

That is, the resistor 14 in the embodiment of the discharge lamp lighting device according to the present invention shown in FIG. 1 has its one end connected to the emitter of the transistor 4 and the other end to the connection point between the ground and the emitter of the transistor 5. It is connected. Therefore, when the drive signal is supplied to the transistor 13 by the operation of the control circuit 12, the base current of the transistors 4 and 5 is supplied via the resistors 6 and 7, whereby either of the transistors 4 and 5 is supplied. Turns on.

When the transistor 4 is turned on first, a current flows from the power source 1 through the primary winding 3a of the transformer 3, the transistor 4, the resistor 14, etc. In other words, a half cycle is applied to the primary side of the transformer 3. Minute current will flow. When the transistor 4 is turned off due to the saturation of the current loop through the transistor 4, the transistor 5 is turned on next, and in such a case, a current flows from the power supply 1 through the primary winding 3b of the transformer 3, the transistor 5, and the like. The current for the remaining half cycle flows through the primary side of the transformer 3.

When the transistor 5 is turned off due to the saturation of the current loop through the transistor 5, the transistor 4 is turned on again, and the current flows through the current loop through the transistor 4 again. Is repeated until the supply of the drive signal from the control circuit 12 to the transistor 13 is stopped. In other words, the oscillating operation in which the ON operation of each of the transistors 4 and 5 is once as one cycle continues. By this operation, the discharge lamp 9 connected to the secondary winding 3c of the transformer 3 is continuously turned on.

In the above operation, in the half cycle in which the transistor 4 is on, the primary side current supplied / input to the transformer 3 flows through the resistor 14 which is the current detecting means,
A voltage drop corresponding to the primary current is generated across the resistor 14. The level of the voltage drop across the resistor 14 is detected by being supplied to the control circuit 12, and the control circuit 12 controls the operation of the transistor 13 according to the detection result of the voltage drop level to control the transformer 3. To control the primary side current supplied to and input to, specifically, the base current of the transistor 4 to control the current value of the primary side current flowing through the transistor 4 to the primary winding 3a of the transformer 3. As a result, the lighting operation of the discharge lamp 9 is controlled to a lighting state in which it is lit at a constant brightness, for example, as in the conventional device described above with reference to FIG.

In the above operation, the primary side current flowing through the primary winding 3b of the transformer 3 in the half cycle in which the transistor 5 is turned on is different from the half cycle in the case where the transistor 4 is turned on. The current does not flow through the resistor 14, which is the detection means, and the current value is further increased. That is, in the present embodiment, the primary side current supplied / input to the primary side of the transformer 3 by the ON operation of the transistors 4 and 5 flows through the resistor 14 which is the current detecting means for the half cycle, and
In each cycle, a current having a different current value is obtained, so that the power consumed by the resistor 14 is halved as compared with that of the conventional device described above with reference to FIG. 2, and the primary current is supplied. As a result, the waveform of the output voltage of the secondary side of the transformer 3 that is output is also controlled to have a waveform in which the areas of the positive and negative regions are different from the ground level.

The resistor 14, which is the current detecting means, is arranged at a location where the primary side current supplied to the primary winding 3a which is the primary side of the transformer 3 through the transistor 4 flows in the present embodiment. However, the location is not limited to the location shown in FIG. 1, and may be located, for example, at a location where the primary side current supplied to the primary side of the transformer 3 through the transistor 5 flows. That is, 1 supplied / input to the primary side of the transformer 3 described above
By arranging at one of the half-cycle primary side currents in the cycle, the same operation as the above-mentioned example can be expected.

[0020]

As described above, the discharge lamp lighting device according to the present invention detects the primary-side current input to the transformer of the push-pull inverter and lights the discharge lamp according to the detected primary-side current. A discharge lamp lighting device is configured by arranging current detection means for controlling the operation of a feedback type regulator for controlling the state at a location where the primary current flows only for half a cycle.

Therefore, there is an effect that it is possible to obtain a discharge lamp lighting device in which the power consumption by the current detecting means can be reduced, and thus the overall size and weight of the device can be reduced. In addition, the secondary side output voltage waveform of the push-pull inverter is
It is possible to obtain a discharge lamp lighting device that does not produce a lighting state with a striped pattern even when a neon discharge lamp is used as the discharge lamp, because it can be distorted so that the waveform has different positive and negative area areas with respect to the ground level. It also has a significant effect.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram showing an embodiment of a discharge lamp lighting device according to the present invention.

FIG. 2 is an electric circuit diagram showing an example of a conventionally known discharge lamp lighting device.

[Explanation of symbols]

 1 Power Supply 2 Push-Pull Inverter 3 Transformer 4 Transistor 5 Transistor 6 Resistor 7 Resistor 9 Discharge Lamp 11 Feedback Regulator 12 Control Circuit 13 Transistor 14 Resistor

Claims (2)

[Claims] 1. A push-pull inverter including a transformer, and a primary-side current having a positive / negative oscillation cycle input to the transformer, the positive-side or negative-side one of the primary-side currents being disposed at a location where the primary-side current flows. Discharge lamp lighting device, comprising: a current detecting unit and a feedback regulator that controls a lighting state of the discharge lamp according to the primary side current detected by the current detecting unit. 2. A push-pull inverter including a transformer, and a supply state of an input current to the transformer is controlled in accordance with a detection output of a current detection means for detecting a primary side current input to the transformer, to control the discharge lamp. A discharge lamp lighting device comprising a feedback type regulator for controlling a lighting state, wherein the current detection means is arranged at a location where the primary side current only flows for half a cycle.