JP3540333B2 - Fluorescent lamp device - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a discharge lamp for originals used for information devices such as facsimile machines, copiers, and image readers, and a display lamp used for display devices such as large display devices and electric bulletin boards.
[0002]
[Prior art]
In recent years, a fluorescent lamp has been used as a light source for illuminating a document of an information device such as a facsimile, a copying machine, or an image reader, or as a display light source for a large-sized color display device. In these applications, the lamp is required to be smaller, have higher brightness, have a longer life, and have higher reliability. Conventionally, there are many restrictions due to having an electrode inside the lamp, and therefore, a fluorescent lamp having no electrode inside the lamp has been considered.
[0003]
FIGS. 7A, 7B, and 7C are a perspective view, a cross-sectional view, and a circuit diagram, respectively, showing a conventional fluorescent lamp disclosed in, for example, Japanese Patent Application Laid-Open No. 3-225745. In the figure, 1 is a fluorescent lamp, 2 is a straight tube-shaped glass bulb in which a rare gas mainly containing xenon gas is enclosed, 3 is a phosphor layer formed on the inner surface of the glass bulb 2, and 4 is generated in the lamp The light output portions 5 and 5b for irradiating the light outside the lamp are made of aluminum foil on both sides along the light output portion 4 and are in close contact with the outer wall of the glass bulb 2 over a substantially entire length with a predetermined width, and are opposed to each other. The band-shaped external electrode 6 is a transparent insulating film of silicon resin coated on the glass bulb 2 including the external electrodes 5a and 5b. Reference numeral 7 denotes a high-frequency lighting circuit for lighting the fluorescent lamp 1, and reference numeral 8 denotes an AC power supply connected to the external electrodes 5a and 5b via the high-frequency lighting circuit 7 and applying a predetermined high-frequency voltage.
[0004]
When a sine-wave AC voltage is applied to the external electrodes 5a and 5b from the high-frequency lighting circuit 7, a discharge of xenon gas occurs in the internal space of the glass bulb 2 sandwiched between the external electrodes 5a and 5b. Ultraviolet rays are generated to excite the phosphor layer 3 formed on the inner surface of the glass bulb 2 to generate visible light, which is emitted from the light output unit 4 to the outside of the lamp.
[0005]
In our research, a fluorescent lamp in which a rare gas is sealed inside such a glass bulb and an external electrode is provided on the outer wall has a rare gas excimer (excimer) on the surface of the electrode inside the glass bulb due to discharge between the electrodes. excimer) is generated, and it is known that the phosphor is excited by ultraviolet rays emitted from the excimer to emit visible light. Therefore, in order to obtain higher luminance efficiently and efficiently, it is sufficient to increase the area of the external electrodes and shorten the distance between the electrodes. Such a fluorescent lamp is disclosed in Japanese Patent Application No. Hei 4-23653.
[0006]
[Problems to be solved by the invention]
Since the conventional fluorescent lamp as described above discharges through a dielectric glass bulb, a high voltage needs to be applied. Also, since the lamp current is determined by the capacitance between the electrodes including the discharge space, in order to obtain higher brightness, the voltage value between the electrodes must be further increased, thereby causing a creeping discharge outside the glass bulb. In addition to the above, there is a problem that the insulation measures on the circuit must be strengthened.
[0007]
SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to obtain a fluorescent lamp device having a large light output without increasing the peak value of the voltage.
Another object is to obtain a fluorescent lamp device having a low discharge starting voltage.
[0008]
[Means for Solving the Problems]
In the fluorescent lamp device according to the present invention, a duty ratio is applied to the conductor in a fluorescent lamp in which a rare gas is sealed in a dielectric discharge vessel having a luminous body on the inner wall and one or more pairs of conductors on the outer wall. A means for applying an AC rectangular pulse voltage of 10% or more is provided , a rare gas excimer is generated in the discharge vessel by a discharge between the conductors, and the phosphor is excited by ultraviolet rays emitted from the excimer to emit visible light. Is emitted . Here, the AC rectangular pulse means a rectangular pulse in which a rest period of voltage 0 is twice in one cycle unless otherwise specified.
[0010]
Further, a means is provided for applying a rectangular pulse voltage of alternating current to the electric conductor on the outer wall once every period in which a zero period of voltage is 0, and excimer of a rare gas is generated in the discharge vessel by electric discharge between the electric conductors. The phosphor is excited by ultraviolet rays emitted from the excimer to emit visible light .
[0011]
[Action]
When an AC rectangular pulse is applied to the fluorescent lamp configured as described above, a discharge occurs due to a sudden change in voltage, generates strong ultraviolet rays, excites the phosphor on the inner wall, and generates a large light output.
[0013]
In addition, in the case of an AC rectangular pulse with a pause period of once per cycle, a large voltage change of peak to peak occurs once per cycle, strong ultraviolet rays are generated, and a phosphor on the inner wall is excited to generate a large light output.
[0014]
【Example】
Embodiment 1 FIG.
An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a fluorescent lamp of the present invention, 2 is a straight cylindrical glass bulb made of lead glass, which is a dielectric material having a diameter of 3 mm and a thickness of 0.3 mm, which constitutes the fluorescent lamp 1, and an inner wall of the glass bulb. The phosphor layer 3 is formed on almost one half of the surface, and the other half is a light output unit 4 for irradiating the light generated inside the lamp to the outside of the lamp. Reference numerals 5a and 5b denote external electrodes, each of which is a conductor having a width of 2.5 mm, provided on the outer wall of the glass bulb 2 with a distance between the electrodes of 0.4 mm. A rare gas mainly composed of xenon is sealed in the glass bulb 2 at a pressure of several tens Torr or more. In FIG. 2, reference numeral 7 denotes a drive circuit which constitutes voltage applying means for lighting the fluorescent lamp 1. The drive circuit 7 is a full bridge circuit comprising switching elements 8a, 8b, 8c, 8d such as transistors. Reference numeral 9 denotes a DC power supply for supplying a DC voltage to the drive circuit 7. The drive circuit 7 is connected to the external electrodes 5a and 5b of the fluorescent lamp 1 by lead wires 10a and 10b.
[0015]
The operation of the fluorescent lamp device having such a configuration will be described. The DC voltage supplied from the DC power supply 9 to the drive circuit 7 is turned on / off by controlling the switching elements 8a, 8b, 8c, 8d, so that a rectangular wave AC voltage is applied between the external electrodes 5a and 5b. , Discharge occurs. The ultraviolet light generated at that time excites the phosphor layer 3 and is converted into visible light determined by the phosphor. The visible light generated from the phosphor is radiated from the light output unit 4.
[0016]
Hereinafter, the characteristics of this discharge will be described in detail. Electric power is applied to the inside of the lamp via a dielectric glass bulb, that is, by capacitive coupling between the external electrode and the discharge gas. The discharge current is limited by the dielectric and does not evolve from glow discharge to arc discharge. Further, the discharge does not concentrate on a specific place, and the discharge is generated from the entire inner surface of the glass bulb facing the external electrode. The discharge starts when a voltage is applied between the external electrodes and the inside of the lamp becomes a dischargeable electric field. Thereafter, charges such as electrons and ions generated by the discharge accumulate on the surface of the glass bulb, and as a result, the electric field inside the lamp is weakened, so that the discharge cannot be sustained and the discharge is stopped. Therefore, a large amount of current flows immediately after the polarity of the applied voltage is reversed, and the current becomes substantially pulse-shaped. When observing the discharge state inside the lamp in detail, it is clear that the entire inner surface of the glass bulb facing the external electrode is almost uniformly covered with light, and that a number of string-like discharges are generated between the paired electrodes. Can be seen.
[0017]
FIG. 3A shows a rectangular pulse voltage waveform applied to the fluorescent lamp 1, and FIG. 3B shows an applied voltage-luminance characteristic at that time. FIG. 3B shows, for comparison, a conventional characteristic of lighting with a sine wave. The sealed gas is xenon 60 Torr, and the frequency of the applied voltage is 40 kHz. The applied voltage is shown as a 0-peak value.
[0018]
From FIG. 3B, it can be seen that, with the same applied voltage, higher luminance is obtained with a rectangular pulse than with a sine wave. This is considered to be due not only to the effect of changing the ratio of the peak value to the effective value of the sine wave but also to the difference in the discharge state between the sine wave and the rectangular pulse. Since the voltage changes gently with a sine wave, thread-like discharges occur at discrete timings, and various states of discharge are observed. For this reason, the discharge conditions are not always optimal for generation of ultraviolet rays. On the other hand, it is considered that a string-like discharge is generated all at once and almost uniformly due to a sudden change in voltage in the rectangular pulse, and a state suitable for generating ultraviolet light is obtained.
[0019]
The discharge start voltage is, for example, 40 kHz, which is about 500 V in the case of a sine wave, and about 430 V in the case of a rectangular pulse, and the discharge start voltage decreases. Therefore, in the case of a rectangular pulse, it is possible to operate at a low peak voltage including the start of discharge. One reason for the phenomenon that the discharge start voltage decreases is that there is a delay time between the start of discharge and the application of voltage. In the case of a sine wave, the peak voltage is applied only instantaneously, but in the case of a rectangular pulse, a high voltage is continuously applied, which has an effect.
[0020]
Embodiment 2. FIG.
FIG. 4A shows a voltage waveform of a rectangular wave having no pause period and a duty ratio of 100%, unlike FIG. 3A. FIG. 4B shows an applied voltage-luminance characteristic when the voltage waveform of FIG. 4A is applied. FIG. 4B shows, for comparison, the case of a rectangular pulse having a pause period (duty ratio 10 to 70%) and a sine wave (FIG. 3B). The frequency of the applied voltage is 80 kHz.
[0021]
From FIG. 4B, it can be seen that when a rectangular pulse having a pause period with a duty ratio of 10% or more is applied, higher luminance is obtained than when a sine wave is applied. In addition, it can be seen that the rectangular wave having the duty ratio of 100% (FIG. 4A) has a much higher luminance than the rectangular pulse having the pause period (FIG. 3A). This is because a rectangular pulse (FIG. 3A) instantaneously generates a voltage difference of 0-peak value, whereas a rectangular wave (FIG. 4A) has a large peak to peak. It is considered that a similar effect as in the case where a high voltage is applied occurs because a voltage difference occurs.
[0022]
Embodiment 3 FIG.
FIG. 5A shows a voltage waveform of a rectangular pulse having one idle period in one cycle, unlike FIG. 3A. FIG. 5 (b) shows a mark or voltage-luminance characteristic when the voltage waveform of FIG. 5 (a) is applied. The characteristics of the voltage waveform in FIG. 3A are shown for comparison. In each rectangular pulse, the period during which the voltage is applied in one cycle is 50%.
[0023]
FIG. 5B shows that the rectangular pulse of FIG. 5A has higher luminance than the rectangular pulse of FIG. 3A. In the case of the rectangular pulse (FIG. 3A), a voltage difference of 0-peak value always occurs instantaneously, whereas in the case of the rectangular pulse of FIG. This is probably because a large voltage difference between peak and peak is generated, and an effect similar to that when a high voltage is applied occurs.
[0024]
Embodiment 4. FIG.
FIG. 6A shows a fluorescent lamp capable of controlling partial light emission by providing a plurality of pairs of external electrodes 5a and 5b on the outer wall of the glass bulb 2 and controlling the voltage applied to each external electrode pair. is there. FIG. 6B shows an image display device in which a plurality of the fluorescent lamps shown in FIG. 6A are arranged. The fluorescent lamp and the image display device having such a configuration are shown in Examples 1 to 4. Waveform voltage application can be applied, and a similar effect can be obtained.
[0025]
The shape and arrangement of the outer wall electrodes are not particularly limited to those shown in the first to fourth embodiments, and may be provided in any shape and arrangement as long as they are arranged in a plane on the outer wall.
[0026]
In the above embodiment, the driving circuit for lighting the fluorescent lamp is also a full-bridge circuit of switching elements. However, a half-bridge circuit may be used, and any drive circuit that can generate a desired voltage waveform may be used. Drive circuit may be used.
[0027]
【The invention's effect】
Since the present invention is configured and operates as described above, it has an effect that a discharge is started at a low voltage and a large light output can be obtained at a low peak voltage.
[Brief description of the drawings]
FIG. 1 is a perspective view of a fluorescent lamp according to an embodiment of the present invention.
FIG. 2 is a diagram showing a fluorescent lamp device according to one embodiment of the present invention.
FIG. 3 is a diagram showing an applied voltage waveform and luminance characteristics according to the first embodiment of the present invention.
FIG. 4 is a diagram showing an applied voltage waveform and luminance characteristics according to a second embodiment of the present invention.
FIG. 5 is a diagram showing an applied voltage waveform and luminance characteristics according to a third embodiment of the present invention.
FIG. 6 is a perspective view showing a fluorescent lamp and an image display device according to Embodiment 4 of the present invention.
FIG. 7 is a perspective view, a sectional view, and a lighting circuit diagram of a conventional fluorescent lamp.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fluorescent lamp 2 Glass bulb of discharge vessel 3 Phosphor layer 5 Conductor external electrode 7 Driving circuit constituting voltage applying means

Claims (2)

A fluorescent lamp in which a rare gas is sealed in a discharge vessel made of a dielectric having a phosphor on the inner wall and one or more conductors on the outer wall, and a duty ratio of 10% or more to the conductor on the outer wall , and Voltage applying means for applying an AC rectangular pulse voltage having a voltage of 0 twice in one cycle, and generating excimer of the rare gas in the discharge vessel by discharging between the conductors, A fluorescent lamp device, wherein the phosphor is excited by ultraviolet light emitted from the excimer to emit visible light . It has a phosphor on the inner wall, and a fluorescent lamp filled with a rare gas in the discharge vessel made of a dielectric material having one or more pairs of conductors on the outer wall, rest period voltage to the conductor of the outer wall 0 1 cycle Voltage applying means for applying a single alternating rectangular pulse voltage to generate excimer of the rare gas in the discharge vessel by discharge between the conductors, and to emit the fluorescent light by ultraviolet rays radiated from the excimer. A fluorescent lamp device for exciting a body to emit visible light .

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