JP2002289390A - Electric discharge lamp equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide electric discharge lamp equipment which can prevent flickers by low power consumption. SOLUTION: An outside electrode type lamp 2, which is effective as an electric discharge lamp, for example, a light source for a back light of a liquid crystal display, is made to turn on by an inverter circuit 1. A resistance 5 for preventing flickers which degrade quality of an image at the time of low luminosity lighting is connected to one end of a 1st switching circuit 4 of the inverter circuit 1. A switching circuit 6 controlled to a non-conduction state at the time of low luminosity lighting, is connected with parallel connection to this resistance 5. Further, to this parallel connection circuit, a parallel connection circuit of a resistance 7 for preventing the flicker at the time of low luminosity illumination and a switch circuit 17, is connected. The fluorescence lamp lighting equipment 12 is constituted by connecting a 2nd switching circuit 8 between the other end of this resistance 7 and the ground.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp device, and more particularly to a discharge lamp suitable for use in an exposure light source used for information equipment such as a copying machine, a facsimile, a scanner, and a backlight device for a liquid crystal display. Related to the device.

[0002]

[Prior Art] Entering the multimedia age, personal computers,
Many types of information are exchanged by digital cameras, digital TVs, mobile phones, in-vehicle navigation, and the like. As a display device of these devices, a liquid crystal display device is mainly used.

This liquid crystal display device uses a backlight as a light source. In general, a cold cathode lamp is used as a light source for the backlight, but further high performance lamps and discharge lamp driving devices are expected as a light source for the backlight.

In response to these expectations, inner and outer electrode type discharge lamps have been developed. That is, this lamp has a glass tube in which a phosphor film is formed on an inner wall surface and a discharge medium such as a rare gas is sealed, and an internal electrode which is sealed by leading a lead terminal to one end side of the glass tube. And a fluorescent lamp having an outer electrode wound around the outer periphery of the glass tube at a required pitch along the tube axis direction.

The external electrode type fluorescent lamp has an outer diameter of 1.2.
Xenon gas is sealed as a discharge medium with a length of about 30 mm to about 600 mm and a length of about 30 mm to about 600 mm. The external electrode is covered with a translucent heat-shrinkable tube serving as a coating. As a method of lighting such an external electrode fluorescent lamp, a rectangular wave voltage is applied to light the lamp.

[0006]

However, particularly in fluorescent lamps used in these apparatuses, there is a demand for further improvement of image quality without flicker and lower power consumption. The present inventor has studied these issues,
In the course of its development, if measures were taken to prevent flicker, the power consumption would become extremely large, and a practical drive circuit could not be provided.

For example, flicker prevention in a switching circuit
If a 0.1 Ω resistor is connected,
2A current flows at the timing of
= I ²When multiple lighting (6 lights) is connected from R, it becomes 2.4W
Also.

That is, if a resistor of 1/4 W is used as the flicker preventing resistor, the derating becomes 160%, which is an operation state which greatly exceeds 50% of the designed value, and the temperature becomes 100 ° C. or more when the temperature is increased. Not desirable for safety measures.

An object of the present invention is to provide a discharge lamp device in which flicker during low-luminance lighting (display) is prevented and power consumption during high-luminance lighting (display) is reduced.

[0010]

SUMMARY OF THE INVENTION The present invention has been found to cause a problem in illumination due to flickering of the discharge lamp during low-brightness lighting, and does not hinder flickering during high-brightness lighting.

It has been found that the luminance which hinders the flicker is about 10% or less when displayed in terms of dimming degree.

In order to achieve the above object, a discharge lamp device according to a first aspect is connected to the switching circuit in a discharge lamp device for applying a rectangular waveform voltage generated by a switching operation to a discharge lamp and lighting the discharge lamp. A resistive element, an open / close circuit connected in parallel to the resistive element, and control means for controlling the open / close circuit to a conductive state when the discharge lamp emits high-luminance light and to a non-conductive state when the discharge lamp emits low-luminance light. It is characterized by becoming.

According to a second aspect of the present invention, an external electrode and an internal electrode of the discharge lamp are connected to a secondary winding circuit of the step-up transformer.
In a discharge lamp device for connecting a switching circuit for generating a rectangular wave voltage by a switching operation to a primary winding circuit and lighting and driving the discharge lamp, the switching circuit includes first and second switching elements connected in series. A first and a second resistive element connected in series to each of the first and second switching elements;
A switching circuit connected in parallel to at least one of the resistive elements and the second resistive element; a connection circuit connected from a series connection circuit of the first and second switching elements to one end of the step-up transformer; A control means is provided for controlling the switching circuit to be in a conductive state when the discharge lamp emits high luminance light and to be in a non-conductive state when the discharge lamp emits low luminance light.

According to a third aspect of the present invention, there is provided a discharge lamp device.
In the item, the light control range is 11 to 10 when the high-luminance light is emitted.
0%, and is 10% or less in the dimming range during the low-luminance emission.

According to a fourth aspect of the present invention, there is provided a discharge lamp device.
In the paragraph, the resistive element is a resistor or an inductance.

According to a fifth aspect of the present invention, there is provided a discharge lamp device.
In any one of the preceding items, the resistive element has a resistance of 0.05 to
It is characterized by being 10Ω.

The discharge lamp is optimally of a type in which a rectangular wave-like discharge voltage is applied between an internal electrode provided in an airtight container of the discharge lamp and an external electrode provided on a peripheral wall surface outside the airtight container to light the discharge lamp. . The outer surface electrode provided on the outer wall surface of the hermetic container may be any electrode provided outside the hermetic container, such as a curved electrode or an electrode wound in a coil shape around the outer peripheral wall surface of the hermetic container.

The means for supplying a switching current to the switching circuit via a resistive element for reducing flicker during the low-luminance lighting period of the discharge lamp is automatically switched when the discharge lamp is illuminated at a low luminance. Is configured to flow through the resistive element.

The means may be an element in which the resistance value of the resistive element changes according to the switching current value, in addition to the switching means. For example, at low brightness lighting current, the resistance value is low resistance,
In the case of a high-brightness lighting current, an element whose resistance value is conductive may be connected.

The high and low brightness can be adjusted by changing the amount of the pulse current flowing through the discharge lamp to achieve the desired brightness. For example, the pulse width is adjusted to a desired luminance.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a discharge lamp device according to the present invention will be described with reference to FIGS. FIG. 1 is a circuit connection diagram at the time of high luminance lighting for describing an embodiment applied to a fluorescent lamp lighting device. 2A and 2B are cross-sectional views for explaining the configuration of the fluorescent lamp of FIG. 1, wherein FIG. 2A is a cross-sectional view of the fluorescent lamp, and FIG. 2B is a schematic circuit diagram for lighting the fluorescent lamp of FIG. is there.

Embodiment 1 First, the configuration of a fluorescent lamp lighting device will be described with reference to FIG. This circuit is an embodiment in which an inverter circuit 1 turns on a discharge lamp, for example, a rare gas fluorescent lamp 2 of an external electrode type. The fluorescent lamp 2 is an external electrode type fluorescent lamp effective as a light source for a backlight of a liquid crystal display device. The inverter circuit 1 is configured to convert a DC voltage generated in a DC voltage circuit 3 from a DC power supply into an AC voltage having a frequency of 60 Hz to 25 kHz, and discharge and light the fluorescent lamp 2.

Next, the inverter circuit 1 will be described.
One end of a first switching circuit 4 is connected to the DC voltage circuit 3. The circuit 4 has a switching circuit configuration using, for example, a MOSFET transistor (hereinafter abbreviated as FET). The other end of the first switching circuit 4 is connected to a resistive element, for example, a 0.1 Ω resistor 5 in order to reduce or prevent flickering that degrades image quality during low luminance lighting.

A second switching circuit 6 which is controlled to be in a conductive state at the time of high luminance lighting is connected in parallel to the resistor 5. The second switching circuit 6 can be constituted by a MOSFET. The parallel connection circuit is connected with a resistor 7 for preventing the flicker at the time of the low-luminance lighting. It is.

If the resistance value is 10 Ω or more, it is not desirable because the heat generation and waveform of the resistance itself are blunted. A third switching circuit 8 is connected between the other end of the resistor 7 and the ground.
Is connected. The first and third switching circuits 4 and 8 may be transistors, photocouplers, or the like in addition to the MOSFETs.

One end of a step-up transformer 9 is connected to the resistor 5, 7 connection circuit, and 10 pF to 10 pF is connected between the other end of the transformer 9 and the DC voltage circuit 3 for switching.
The first capacitor 10 having a capacitance of 0 μF, for example, 10 μF is connected. Further, a second capacitor 11 having a capacitance of 10 pF to 100 μF, for example, 10 μF, is connected between the other end of the transformer 9 and the ground. Thus, the fluorescent lamp lighting device 12 is configured.

Next, the configuration of the external electrode type fluorescent lamp 2 will be described with reference to FIG. This external electrode type fluorescent lamp 2 is used as a light source for a backlight of a liquid crystal display device. In general, a cold cathode lamp is used as a light source for a backlight, but a further high-performance lamp and a discharge lamp driving device therefor are required as a light source for a backlight.

This high performance lamp is an external electrode type fluorescent lamp 2 as shown in FIG. This fluorescent lamp 2
Is as follows. FIG. 2 is a sectional view for explaining an embodiment of the external electrode type fluorescent lamp 2. The same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

The glass tube 21 is a glass tube having a phosphor layer 22 provided on the inner wall surface.
A discharge medium containing at least xenon as a rare gas is sealed. At least one end of the glass tube 21 is sealed with an internal electrode 24 via a lead wire 23.

On the outer wall surface of the glass tube 21, a conductive material having an arbitrary shape is provided as an external electrode along the tube axis direction. This external electrode is an external electrode in which, for example, a linear conductive material (metal wire) 25 is spirally wound on the outer wall surface of the glass tube 21 at a required pitch along the tube axis direction. This outer surface electrode is covered with, for example, a translucent heat-shrinkable tube.

The outer electrode is made of a light-transmitting resin film 26.
For example, a glass tube 21 is coated with a light-transmitting heat-shrinkable tube.
By firmly fixing the electrodes on the wall surface, the electrode is not displaced.

The internal electrode 24 is connected to one end of a voltage supply source 29 via an introduction line 23 and a voltage supply line 28. Further, the outer surface electrode 25 is connected to a voltage supply source 30 via a fixing metal bar 27 and a voltage supply line 29. Thus, the external electrode type fluorescent lamp 2 is configured. The outer electrode type fluorescent lamp 2 has an outer diameter of, for example, about 1.2 mm to 10.0 mm and a length of, for example, 30 mm to
It is about 600 mm.

The lighting device 1 for the external electrode type fluorescent lamp 2
2 is configured as shown in FIG. When a rectangular wave voltage is applied to the fluorescent lamp 2 from the voltage supply source 30 of the lighting device 12, the external electrode type fluorescent lamp 2 starts discharging between the internal electrode 24 and the external electrode 25. This discharge radiates ultraviolet rays from the xenon gas. The ultraviolet light causes the phosphor layer 22 to emit light and is converted into visible light, which is used as a light source.

As a lamp current waveform for lighting the external electrode type fluorescent lamp 2, a pulse current for a lamp voltage of a rectangular wave as shown in FIG. The external electrode type fluorescent lamp 2 is lit when a current flows at the rise and fall of the rectangular wave.

Next, the lighting operation of the fluorescent lamp 2 will be described with reference to FIG.
This will be specifically described with reference to FIG. FIG. 3 is a signal waveform diagram for causing the fluorescent lamp lighting device 12 shown in FIG. 1 to operate with low power consumption at the time of high luminance lighting, and to perform a low flickering operation at the time of low luminance lighting.

First, high brightness lighting will be described with reference to FIGS. 1 (a) and 1 (b). FIG. 1A shows a circuit in which the first switching circuit 4 is in a conduction period, and FIG. 1B shows a circuit in which the third switching circuit 8 is in a conduction period.

The second switching circuit 6 corresponds to the circuit shown in FIG.
Is controlled by the open / close control signal (control signal). This signal controls the second switching circuit 6 to be conductive during the positive square wave signal period, and controls the second switching circuit 6 to be non-conductive during the negative square wave signal period.

The first switching circuit 4 is shown in FIG.
Is controlled by the open / close control signal (drive signal 1).
This signal controls the first switching circuit 4 to be conductive during the positive rectangular wave signal period, and controls the first switching circuit 4 to be non-conductive during the negative rectangular wave signal period.

The third switching circuit 8 is shown in FIG.
Is controlled by the open / close control signal (drive signal 2).
This signal controls the third switching circuit 8 to be in a conductive state during a positive square wave signal period, and controls the third switching circuit 8 to be in a non-conductive state during a negative square wave signal period.

The circuits shown in FIGS. 1 (a) and 1 (b) are circuits showing a high-luminance lighting state. That is, a state in which the positive rectangular wave signal of FIG. 3B is applied to the second switching circuit 6 is shown, and a conductive state is shown. That is, it indicates that the flicker preventing resistor 5 is brought into a short-circuit state.

First and second switching circuits 4, 8
3 (c) and 3 (d) are applied to each other, and the flicker preventing resistor 5 is short-circuited while the positive rectangular wave signal shown in FIG. 3 (b) is applied. Since it is controlled, a current flows in the direction indicated by arrow 13. Therefore, since no current flows through the resistor 5, the power consumption of the resistor can be reduced.

FIG. 1B shows a circuit during a period when the positive rectangular wave signal shown in FIG. 3D is applied. During this period, a current flows in the direction indicated by the arrow 14 and flows through the resistor 7 via the step-up transformer 9. Therefore, during this period, power is consumed by the flicker preventing resistor 7. Therefore,
In this embodiment, power consumption during a half cycle can be reduced.

Next, low brightness lighting will be described with reference to FIGS. 4 (a) and 4 (b). FIGS. 4A and 4B are circuit connection diagrams for explaining the operation at the time of low luminance lighting in FIG.

To turn on the circuit 12 with low luminance, the second switching circuit 6 is controlled to open and close by the negative signal waveform shown in FIG. The first switching circuit 4 is controlled by the drive signal shown in FIG. The second switching circuit 8 is controlled by the drive signal shown in FIG.

As a result, the currents are not
5A and 5B, the currents indicated by arrows 15 and 16 alternately flow through the resistors 5 and 7, and the rising and falling characteristics of the rectangular wave voltage waveform applied to the fluorescent lamp 2 are blunted. Preventing.

Embodiment 2 Next, another embodiment of FIGS. 1 and 4 will be described with reference to FIGS. The same elements as those in FIGS. 1 to 4 are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 5 is a circuit diagram for explaining the operation at the time of high luminance lighting, and FIG. 6 is a circuit diagram for explaining the operation at the time of low luminance lighting.

A technique different from that of the first embodiment is that the fourth switching circuit 17 for switching between high-luminance lighting and low-luminance lighting includes a resistor 7
Are connected in parallel. The same reference numerals are given to the same circuits as those in the above embodiment, and the detailed description thereof will be omitted.

This circuit is an embodiment in which a discharge lamp, for example, a rare gas fluorescent lamp 2 is turned on by an inverter circuit 1. The inverter circuit 1 is configured to convert a DC voltage 3 from a DC power supply into a rectangular wave voltage having a frequency of 60 Hz to 25 kHz by the inverter circuit 1 and discharge and light the fluorescent lamp 2 using the rectangular wave voltage.

The inverter circuit 1 will be described.
One end of a first switching circuit 4 is connected to the DC voltage circuit 3. A resistor 5 is connected to the other end of the first switching circuit 4. A resistor 7 is connected to the resistor 5 in series.

A third switching circuit 8 is connected between the other end of the resistor 7 and the ground. One end of a step-up transformer 9 is connected to the resistors 5 and 7 connection circuit, and a first capacitor 10 is connected between the other end of the transformer 9 and the DC voltage circuit 3. Further, a second capacitor 11 is connected between the other end of the transformer 9 and the ground. In this embodiment, a fourth switching circuit 17 is connected in parallel with the resistor 7. Thus, the fluorescent lamp lighting device 12 is configured.

Next, the lighting operation of the fluorescent lamp lighting device 12 will be described with reference to FIG. FIG. 3 is a waveform diagram for driving the fluorescent lamp lighting device 12 for high-luminance lighting and low power consumption driving, and for low-luminance lighting and low flickering driving.

First, high brightness lighting will be described with reference to FIGS. 5 (a) and 5 (b). FIG. 5A shows a circuit in which the first switching circuit 4 is in a conduction period, and FIG. 5B shows a circuit in which the third switching circuit 8 is in a conduction period.

The fourth switching circuit 17 corresponds to FIG.
Opening / closing is controlled by the opening / closing control signal of (b). This signal controls the fourth switching circuit 17 to be conductive during the positive square wave signal period, and controls the fourth switching circuit 17 to be non-conductive during the negative square wave signal period.

The third switching circuit 8 is shown in FIG.
Is controlled by the open / close control signal. This signal controls the third switching circuit 8 to be in a conductive state during a positive square wave signal period, and controls the third switching circuit 8 to be in a non-conductive state during a negative square wave signal period.

The circuits shown in FIGS. 5A and 5B are circuits showing a high-luminance lighting state. That is, the fourth switching circuit 1
Reference numeral 7 denotes a state in which the positive rectangular wave signal shown in FIG. 3B is applied, and controls the resistor 7 to a short-circuit state.

First and third switching circuits 4, 8
Is controlled by the opposing drive signals shown in FIGS. 3 (c) and 3 (d). FIG. 5A shows a circuit during a period in which the positive rectangular wave signal of FIG. 3C is applied.

During this period, a current flows in the direction indicated by arrow 13, and a current flows through step-up transformer 9 via resistor 5.
Accordingly, during this period, power is consumed by the flicker preventing resistor 5.

During the period in which the positive rectangular wave signal is applied in FIG. 3D, the flicker preventing resistor 7 is controlled to be in a short-circuit state, so that a current flows in the direction indicated by the arrow 14. Therefore, at the time of high luminance lighting, no current flows through the resistor 7,
The power consumption of the resistor can be reduced.

That is, in this embodiment, power consumption during a half cycle period can be reduced.

Next, low brightness lighting will be described with reference to FIGS. 6 (a) and 6 (b). 6A and 6B are circuit connection diagrams for explaining the operation at the time of low-luminance lighting in FIG.

In order to make this circuit 12 emit light with low luminance, the fourth switching circuit 17 is controlled by the negative rectangular waveform shown in FIG. The first switching circuit 4 is controlled by the drive signal shown in FIG. The opening and closing of the third switching circuit 8 is controlled by the drive signal shown in FIG.

As a result, the electric currents are
5A and 5B, the currents indicated by arrows 15 and 16 alternately flow through the resistors 5 and 7, and the rising and falling characteristics of the rectangular wave voltage waveform applied to the fluorescent lamp 2 are blunted. Preventing.

Embodiment 3 Next, a description will be given of an embodiment in which the power consumption is reduced during the entire operation during the high-luminance lighting and the flicker during the entire operation during the low-luminance lighting is prevented.
An embodiment in which the second and fourth switching circuits 6 and 17 are connected in parallel to the flicker preventing resistors 5 and 7, respectively, will be described with reference to FIGS. FIG. 7 is a circuit configuration diagram for explaining the operation at the time of high luminance lighting, and FIG. 8 is a circuit configuration diagram for explaining the operation at the time of low luminance lighting.

In this embodiment, power-saving lighting is performed during the conduction period of the first and third switching circuits 4 and 8 during high-luminance lighting, and non-power-saving lighting of the first and third switching circuits 4 and 8 during low-luminance lighting. This is an optimal embodiment capable of preventing flicker during the conduction period.

The same reference numerals are given to the same circuits as those in the above embodiment, and the detailed description thereof will be omitted.

In this circuit, a discharge lamp, for example, a rare gas fluorescent lamp 2 is turned on by an inverter circuit 1. The inverter circuit 1 converts the DC voltage 3 from the DC power supply into the inverter circuit 1
Is converted into a rectangular wave voltage having a frequency of 60 Hz to 25 kHz, and the fluorescent lamp 2 is discharged and lit by the rectangular wave voltage.

The inverter circuit 1 will be described.
One end of a first switching circuit 4 is connected to the DC voltage circuit 3. The other end of the first switching circuit 4 is connected to a resistor 5 for preventing flicker at the time of low luminance lighting. The resistor 5 is connected in parallel with a second switching circuit 6 for switching and selecting between high and low luminance.

Further, a resistor 7 is connected to the resistor 5 in series. The resistor 7 is connected in parallel with a fourth switching circuit 17 for switching between high and low luminance.

A third switching circuit 8 is connected between the other end of the resistor 7 and the ground. One end of a step-up transformer 9 is connected to the resistors 5 and 7 connection circuit, and a first capacitor 10 is connected between the other end of the transformer 9 and the DC voltage circuit 3. Further, a second capacitor 11 is connected between the other end of the transformer 9 and the ground. In this embodiment, a fourth switching circuit 17 is connected in parallel with the resistor 7. Thus, the fluorescent lamp lighting device 12 is configured.

Next, the lighting operation of the fluorescent lamp lighting device 12 will be described with reference to FIG. FIG. 3 is a waveform diagram for driving the fluorescent lamp lighting device 12 for high-luminance lighting and low power consumption driving, and for low-luminance lighting and low flickering driving.

First, high brightness lighting will be described with reference to FIGS. 7 (a) and 7 (b). In both of the circuits shown in FIGS. 7A and 7B, the second and fourth switching circuits 6 and 17 are in the high luminance lighting period.
Is conductive. FIG. 7A shows a circuit in which the first switching circuit 4 is in the conduction period, and FIG. 7B shows a circuit in which the third switching circuit 8 is in the conduction period.

Second and fourth switching circuits 6, 1
7 is applied with the open / close control signal shown in FIG. This signal controls the second and fourth switching circuits 6, 17 to be conductive during the positive rectangular wave signal period, and controls the second and fourth switching circuits 6, 1 during the negative rectangular wave signal period.
7 is turned off.

The first switching circuit 4 has the configuration shown in FIG.
(C) Open / close control signal is applied. This signal controls the first switching circuit 4 to be conductive during the positive rectangular wave signal period, and controls the first switching circuit 4 during the negative rectangular wave signal period.
Is turned off.

The third switching circuit 8 has the configuration shown in FIG.
The switching control signal of (d) is applied. This signal controls the third switching circuit 8 to be conductive during the positive rectangular wave signal period, and controls the third switching circuit 8 during the negative rectangular wave signal period.
Is turned off.

The circuits shown in FIGS. 7A and 7B are circuits showing a high-luminance lighting state. That is, a state in which the positive rectangular wave signal shown in FIG. 3B is applied to the second and fourth switching circuits 6 and 17 is shown, and the resistors 5 and 7 are controlled to be in a short-circuit state.

First and third switching circuits 4, 8
3 (c) and 3 (d) are applied to each other. FIG. 7A shows a circuit during a period in which the positive rectangular wave signal shown in FIG. 3C is applied. During this period, a current flows in a direction indicated by an arrow 13, and a current flows to the step-up transformer 9 via the second switching circuit 6. Accordingly, during this period, since the flicker preventing resistor 5 is controlled to be in a short-circuit state, no current flows through the flicker preventing resistor 5, and accordingly, power consumption is reduced accordingly.

FIG. 7B shows a circuit during a period when the positive rectangular wave signal shown in FIG. 3D is applied.

In the period in which the positive rectangular wave signal is applied in FIG. 3D, the flicker preventing resistor 7 is controlled to be in a short-circuit state, so that a current flows in the direction indicated by the arrow 14. Accordingly, no current flows through the resistors 5 and 7 during all periods of high-luminance lighting, so that the power consumption of the resistors 5 and 7 can be reduced.

Next, low brightness lighting will be described with reference to FIGS. 8 (a) and 8 (b). FIGS. 8A and 8B are circuit connection diagrams for explaining the operation at the time of low luminance lighting in FIG.

In order to light this circuit 12 with low luminance, both the second and fourth switching circuits 6 and 17 are controlled to open and close by the negative rectangular wave signal waveform shown in FIG. The first switching circuit 4 is shown in FIG.
Is controlled by the drive signal. Third switching circuit 8
Is controlled by the drive signal shown in FIG.

As a result, the current is equal to the current of FIG.
5A and 5B, the currents indicated by arrows 15 and 16 alternately flow through the resistors 5 and 7, and the rising and falling characteristics of the rectangular wave voltage waveform applied to the fluorescent lamp 2 are blunted. Preventing. That is, it is possible to prevent the occurrence of flickering during the entire period of the low luminance lighting.

Embodiment 4 In the above embodiment, lighting of one discharge lamp has been described. An embodiment in which a plurality of discharge lamps are used as light sources will be described below. An embodiment for controlling lighting of three fluorescent lamps will be described. FIG. 9 shows an embodiment in which a plurality of lightings are performed in a case where the low-power means for high-luminance lighting described in the embodiment in FIG. 1 is applied to the resistor 5. The same circuits as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

That is, in this circuit configuration, three sets of one fluorescent lamp driving circuit are provided, and the first and third driving circuits of each driving circuit are provided.
Switching circuits 4 and 8 and the second switching circuit 6
Are driven in parallel.

Therefore, the three sets of first switching circuits 4 are connected in parallel so as to open and close at the same time to supply the rectangular waveform shown in FIG. 3C. Similarly, three sets of second switching circuits 8 are connected in parallel so as to open and close at the same time to supply the rectangular waveform shown in FIG. 3D.

Similarly, three sets of second switching circuits 6 are connected in parallel so as to open and close at the same time to supply the rectangular waveform shown in FIG. 3B. With this configuration, three fluorescent lamps can be turned on in the same manner as one fluorescent lamp. FIG. 9 shows a low power consumption circuit when the three fluorescent lamps 2 are turned on with high luminance. At the time of low-luminance lighting, low-flickering or flicker-prevented lighting can be realized only by supplying the negative rectangular wave signal in FIG. 3E as a control signal to each second switching circuit 6.

Embodiment 5 FIG. 10 shows an embodiment in which a plurality of lightings are applied when the low-power means for high-intensity lighting described in the embodiment in FIG. The same reference numerals are given to the same circuits as those in FIG. 5, and detailed description thereof will be omitted.

That is, in this circuit configuration, three sets of one fluorescent lamp driving circuit are provided, and the first and third driving circuits of these driving circuits are provided.
Switching circuits 4 and 8 and the second switching circuit 6
Are driven in parallel.

Accordingly, the three sets of first switching circuits 4 are connected in parallel so as to open and close at the same time to supply the rectangular signal waveform shown in FIG. 3C. Similarly, three sets of third switching circuits 8 are connected in parallel so as to open and close at the same time, and a rectangular wave signal waveform shown in FIG. 3D is supplied.

Similarly, three sets of second switching circuits 6 are connected in parallel so as to open and close at the same time to supply the rectangular wave signal waveform shown in FIG. 3B. With this configuration, three fluorescent lamps can be turned on in the same manner as one fluorescent lamp. FIG. 10 shows a low-power-consumption circuit when high-luminance lighting is performed. At the time of low-luminance lighting, low-flickering or flicker-prevented lighting can be realized only by supplying the negative rectangular wave signal in FIG. 3E as a control signal to each second switching circuit 6.

Embodiment 6 FIG. 11 shows an embodiment in which a plurality of lightings are performed in a case where the low-power means for high-brightness lighting described in the embodiment in FIG. 7 is applied to the resistors 5 and 7. The same circuits as those in FIG. 7 are denoted by the same reference numerals, and detailed description thereof will be omitted.

That is, in this circuit configuration, three sets of one fluorescent lamp driving circuit are provided, and the first and third driving circuits of these driving circuits are provided.
And the control circuits of the second and fourth switching circuits 6 and 17 are driven in parallel.

Therefore, the first switching circuits 4 are connected in parallel so as to open and close at the same time so as to supply the rectangular wave signal waveform shown in FIG. 3C. Similarly, three sets of third switching circuits 8 are connected in parallel so as to open and close at the same time, and a rectangular wave signal waveform shown in FIG. 3D is supplied.

Similarly, three sets of the second and fourth switching circuits 6 and 17 are connected in parallel so as to open and close at the same time, and a rectangular signal waveform shown in FIG. 3B is supplied. With this configuration, three fluorescent lamps can be turned on in the same manner as one fluorescent lamp. FIG.
Indicates a low power consumption circuit at the time of high luminance lighting. At the time of low-luminance lighting, low-flickering or flicker-prevented lighting can be realized only by supplying the control signal of FIG. 3E to each of the second and fourth switching circuits 6 and 17.

In the above embodiment, with respect to high and low luminance, the low luminance in which flicker occurs or is noticeable is 10 degrees in dimming degree.
% Or less. The high luminance at which no flickering was felt was 11% or more in dimming degree. FIG. 1 illustrates this characteristic.
2. FIG. 12 is a characteristic diagram for explaining the relationship between the dimming degree at which flicker occurs and the luminance according to this embodiment. A low-luminance region having a dimming degree of 10% or less is indicated by a dotted line. A high-luminance region with a dimming degree of 11% or more is indicated by a dotted line.

The method for obtaining the dimming degree will be described with reference to FIG. FIG. 13 is a waveform diagram for exemplifying the dimming degree of FIG. FIG. 13A shows a lighting rectangular wave signal of the fluorescent lamp 2 when the dimming degree is 100% at a dimming frequency of, for example, 100 Hz. FIG. 13B shows the fluorescent lamp 2 when the dimming degree is 1% at a dimming frequency of 100 Hz. 2 shows a lighting rectangular wave signal.

The lighting frequency of the fluorescent lamp 2 is 20 kHz,
Assuming that the dimming frequency is 100 Hz, the dimming degree is 100%.
As shown in FIG. 13A, there are 200 rectangular wave signals of 50 μsec / piece in one period of 10 msec. This rectangular wave signal is supplied to the lighting circuit (FIG. 1,
5, 7, 9, 10).

In this embodiment, the relationship between the dimming degree and the number of rectangular waves (per cycle) X of the drive signal is X / 2
00 = 100% (degree of dimming).

At a dimming degree of 1%, as shown in FIG. 13B, two rectangular waves of 50 μsec / piece exist within one period of 10 msec. This rectangular wave signal is supplied as a drive signal for the lighting circuit (FIGS. 4, 6, and 8) at the time of the low luminance.

At a dimming degree of 10%, there are 20 rectangular waves of 50 μsec / piece in a 10 msec period of one cycle.
This square wave signal is supplied to the lighting circuit (FIGS. 4, 6,
8).

When the lighting frequency changes, the number changes because the time of one rectangular wave changes. Further, as the dimming frequency, 100 to 200 Hz is selected as an optimal example,
Approximately 1 kHz for easy control to obtain desired brightness
The following frequencies are desirable:

Embodiment 7 An embodiment in which power is saved during the high luminance lighting period and flickering is prevented during the low luminance lighting period will be described with reference to FIG.
FIG. 14 is a circuit connection diagram for explaining an embodiment in which power saving and flicker are prevented. The same circuits as those in FIG. 7 are denoted by the same reference numerals, and detailed description thereof will be omitted.

First and third switching circuits 4, 8
Is composed of MOSFETs 31 and 32. Resistors 5 and 7 for preventing flickering are resistors 3 of 0.1Ω.
3, 34 are connected. The second and fourth switching circuits 6, 17 are composed of MOSFETs 35, 36.

That is, during high-luminance lighting, the MOSFET 3
5 and 36 are controlled to a conductive state, and MOSFETs 31 and 3
By applying a lighting pulse so that the electrodes 2 are alternately turned on, power-saving high-luminance lighting can be performed. At the time of low-brightness lighting, the MOSFETs 35 and 36 are controlled to be in a non-conducting state, and a current flows through the resistors 33 and 34 so that the MOSFETs 31 and 3 are turned off.
By applying a lighting pulse so as to alternately make the two conductive states, it is possible to achieve low-brightness lighting in which flicker is prevented.

Regarding the function of preventing the flicker at the time of low luminance, when the primary winding and the secondary winding of the transformer 9 have the same starting position, the negative current flowing through the fluorescent lamp 2 when the MOSFET 31 is in the conductive state is considered. Controls the peak of the pulse current. By controlling the negative pulse current, it is possible to suppress flicker. In this case, the resistance 3
The connection of No. 4 becomes unnecessary.

A major cause of the flicker is a negative pulse current, and the pulse width and peak value of the negative pulse current are controlled so that the flicker does not occur.

Further, if the positive pulse current is not controlled depending on the condition of the fluorescent lamp 2, flickering may occur. This is because when either the positive pulse current or the negative pulse current applied to the fluorescent lamp 2 is increased, the fluorescent lamp 2
A large contrast occurs at either end of the. If the peak current is too high, there is a possibility of flicker during dimming. Therefore, the resistor 5 is connected so that the fluorescent lamp 2 does not flicker, and the current pulse width and the peak current are controlled.

Further, when the winding direction of the transformer 9 is different, the negative pulse current of the third switching circuit 8 is controlled conversely. Therefore, in this embodiment, the resistors 5, 7, 33, and 34 are connected in each embodiment so as to cope with the case where the winding direction of the transformer 9 is different.

In the above embodiment, the backlight for the liquid crystal display device has been described. However, similar effects can be obtained by applying the invention to other discharge lamps. For example, for OCR, FA
The present invention may be applied to a light source for X, and is not limited to an inner / outer electrode type discharge lamp, but may be an electrode type discharge lamp only inside an airtight container or an electrode type discharge lamp only outside an airtight container.

[0110]

According to the discharge lamp device of the present invention, it is possible to obtain a discharge lamp device capable of preventing flicker with low power consumption.

[Brief description of the drawings]

FIG. 1 is a circuit connection diagram at the time of high-brightness lighting for describing an embodiment of a discharge lamp device of the present invention.

FIG. 2 is a sectional view for explaining the structure of the external electrode type fluorescent lamp of FIGS.

FIG. 3 is a pulse waveform chart for explaining the operation of the discharge lamp device of FIG.

FIG. 4 is a circuit connection diagram for explaining the embodiment at the time of low-luminance lighting in FIG. 1;

FIG. 5 is a circuit connection diagram at the time of high-brightness lighting for explaining another embodiment of FIG. 1;

FIG. 6 is a circuit connection diagram for explaining the embodiment at the time of low-luminance lighting in FIG. 5;

FIG. 7 is a circuit connection diagram at the time of high-brightness lighting for explaining another embodiment of FIG. 1;

FIG. 8 is a circuit connection diagram for explaining the embodiment at the time of low-luminance lighting in FIG. 7;

FIG. 9 is a circuit diagram at the time of high-brightness lighting for explaining another embodiment of FIG. 1;

FIG. 10 is a circuit diagram at the time of high-brightness lighting for explaining another embodiment of FIG. 1;

FIG. 11 is a circuit diagram at the time of high-brightness lighting for explaining another embodiment of FIG. 1;

FIG. 12 is a characteristic diagram for explaining the relationship between the dimming degree and the relative luminance in FIGS.

FIG. 13 is a waveform chart for explaining a control signal waveform at each dimming degree in FIG. 12;

FIG. 14 is a circuit connection diagram at the time of high-brightness lighting for explaining the embodiment of FIG. 7;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1: Inverter circuit, 2: Fluorescent lamp, 3: DC voltage circuit, 4, 6, 8, 17 ... Switching circuit, 5, 7, 3
3, 34: resistor, 9: step-up transformer, 10, 11: capacitor, 12: fluorescent lamp lighting device, 13, 14, 1
5, 16 ... arrow, 31, 32, 35, 36 ... MOSFE
T.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3K072 AA19 AA20 AC01 AC11 CA03 GB12 GC07 HA02 3K098 CC24 CC40 CC41 CC70 DD01 DD20 DD37 DD43 EE31 EE32 EE35 EE40 GG01 GG03

Claims (5)

[Claims] 1. A discharge lamp device for applying a rectangular waveform voltage generated by a switching operation to a discharge lamp and lighting the discharge lamp, comprising: a resistive element connected to the switching circuit; and an opening and closing connected in parallel to the resistive element. A discharge lamp device comprising: a circuit; and control means for controlling the open / close circuit to be in a conductive state when the discharge lamp emits high luminance light and to be in a non-conductive state when the discharge lamp emits low luminance light. 2. The discharge lamp according to claim 1, wherein an external electrode and an internal electrode of the discharge lamp are connected to a secondary winding circuit of the step-up transformer, and a switching circuit for generating a rectangular wave voltage by a switching operation is connected to the primary winding circuit. Wherein the switching circuit comprises a first and a second connected in series.
Switching element, first and second resistive elements connected in series to the first and second switching elements, and parallel to at least one of the first and second resistive elements A switching circuit connected thereto, a connection circuit connected from a series connection circuit of the first and second switching elements to one end of the step-up transformer, and setting the switching circuit to a conductive state when the discharge lamp emits high-intensity light, A discharge lamp device comprising: control means for controlling a non-conduction state during low-luminance light emission. 3. A light control range of 11 to 1 during high-luminance light emission.
3. The discharge lamp device according to claim 1, wherein the light intensity is 00%, and the light control range is 10% or less during the low-luminance light emission. 4. 4. The discharge lamp device according to claim 1, wherein the resistive element is a resistor or an inductance. 5. The discharge lamp device according to claim 1, wherein the resistive element has a resistance of 0.05 to 10Ω.