JP2006049236A - Discharge lamp device, light source device, and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp device capable of controlling a dark position at lighting, and a well-proportioned light source device using the same. <P>SOLUTION: In the discharge lamp device (10) lighted by a single lighting circuit (13) impressing a voltage between a plurality of inner electrodes (21) and outer electrodes (22), positions of dark parts generated at the lighting of a light-emitting tube (20) are regulated to required positions by differentiating the voltages (V2, V3) impressed on each of the plurality of inner electrodes (21) from each other by a voltage conversion means (13F). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a discharge lamp device including an arc tube in which a discharge medium is sealed and an electrode for exciting the discharge medium, a light source device using the same, and a liquid crystal display device.

  In recent years, with the development of liquid crystal technology, liquid crystal displays are widely used as display devices such as televisions and monitors. The liquid crystal display has a structure in which a light source device (hereinafter referred to as “backlight”) that emits light in a planar shape is disposed on the back surface of the liquid crystal, and a screen is displayed by transmitting light from the backlight.

  In addition to research on discharge lamps using mercury as the main light source for backlights, research on backlights using discharge lamps that use rare gases without using mercury (hereinafter referred to as “mercury-less backlights”) is being conducted. It is being done easily. Since the mercury-less backlight does not use mercury, the luminous flux rises quickly because it does not cause a decrease in luminous efficiency due to an increase in mercury temperature. In addition, a mercury-less backlight is environmentally preferable.

  Mercury-less backlights have a thin tube structure, and it is necessary to increase the luminance and luminous efficiency. Therefore, the mercury-less backlight has a structure that is lit by applying a voltage between the inside of the arc tube and the electrode formed outside the arc tube. A discharge lamp apparatus using a rare gas has been studied.

  As shown in FIG. 15, the discharge lamp device using the rare gas includes a discharge vessel 1 in which the rare gas is sealed, a pair of internal electrodes 2 sealed at both ends of the discharge vessel 1, and the outer surface of the discharge vessel 1. A discharge lamp DL having an external electrode 3 extending in the longitudinal direction is disclosed (see Patent Document 1). In this discharge lamp, a dark portion (hereinafter referred to as “central dark portion”) generated when the discharge lamp DL is turned on by applying a voltage from the high-frequency power source 6 between the internal electrode 2 and the external electrode 3 sealed at both ends. Is improved by arbitrarily changing the shape and area of the external electrode to improve the light distribution.

  In addition, as shown in FIG. 16, the arc tube 1 in which the rare gas is sealed, and a plurality of external electrodes 7a and 7b that are spirally formed on the outer surface of the arc tube and insulated from each other are arranged in an insulated relationship with each other. In addition, a rare gas discharge lamp is disclosed that includes internal electrodes 8a and 8b formed in the arc tube 1 so as to correspond to the external electrodes 7a and 7b, respectively (see Patent Document 2). This discharge lamp device uses a plurality of lighting circuits 9a and 9b to apply a voltage between the plurality of internal electrodes 8a and 8b and the external electrodes 7a and 7b, and discharge them independently, thereby reducing luminance and shortening the service life. Is to improve.

JP 2000-40494 A JP 2001-313002 A

  However, in the configuration shown in FIG. 15, in order to reduce the central dark portion, the current density must be designed to a specified value. Even in that case, the degree of the central dark part is improved to some extent, and the central dark part cannot be completely eliminated. There is also a problem that the dark part is always located at the center of the lamp.

  Furthermore, when a plurality of discharge lamps are arranged to form a light source device (backlight), there is a problem that uniform light emission cannot be obtained because the central dark portion of the lamp is concentrated.

  In addition, as shown in FIG. 16, when a plurality of electrodes and lighting circuits are provided separately in one arc tube, the central dark portion can be determined by the arrangement of the external electrodes 7a and 7b. There is a problem that multiple pipes are required. Furthermore, when changing the position of a dark part, it was necessary to newly manufacture another discharge lamp, and the man-hour was required.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a discharge lamp device capable of controlling the position of the central dark portion with a single lighting circuit and a light source device using the same. There is.

  A first light source device according to the present invention includes a plurality of arc tubes each having at least two internal electrodes and an external electrode that are provided to face each other and enclosing a discharge medium, and light from the plurality of arc tubes. A light guide plate that receives and propagates light, a lighting circuit that generates a voltage for applying a voltage to the internal and external electrodes of the arc tube, and an internal electrode and an external electrode of each arc tube that convert the output voltage from the lighting circuit And a voltage conversion means for applying to. The plurality of arc tubes are arranged in parallel. In each arc tube, the voltage conversion means applies a voltage of different polarity to the internal electrode and the external electrode, and applies a voltage of the same polarity and different magnitude to each of the internal electrodes. The voltage conversion means controls the difference in voltage applied to each internal electrode of each arc tube so that the positions of dark portions generated in the plurality of arc tubes are scattered and distributed.

  A second light source device according to the present invention includes at least two internal electrodes provided opposite to each other, a plurality of arc tubes each having an external electrode and sealed with a discharge medium, and light from the plurality of arc tubes. A light guide plate that receives and propagates light, a lighting circuit that generates a voltage for applying a voltage to the internal and external electrodes of the arc tube, and an internal electrode and an external electrode of each arc tube that convert the output voltage from the lighting circuit And a voltage conversion means for applying to. The arc tube has a bent portion, and is disposed on the side of the light guide plate so that the bent portion is positioned near the corner of the light guide plate. In each arc tube, the voltage conversion means applies a voltage of different polarity to the internal electrode and the external electrode, applies a voltage of the same polarity and a different magnitude to each of the internal electrodes, and the dark portion of the arc tube The difference in the voltage applied to each internal electrode of the arc tube is controlled so that is generated at the bent portion.

  In the light source device, the voltage conversion means may include a capacitor connected in series between the lighting circuit and the internal electrode.

  In the light source device, at least two internal electrodes may be provided at both ends of the arc tube.

  In the light source device, the external electrode may be grounded.

  A liquid crystal display device according to the present invention includes a liquid crystal panel and the light source device that supplies illumination light to the liquid crystal panel.

  A discharge lamp device according to the present invention includes an arc tube having at least two internal electrodes provided opposite to each other and an external electrode, in which a discharge medium is enclosed, and applies a voltage to the internal electrode and the external electrode of the arc tube A lighting circuit for generating a voltage to be applied, and voltage conversion means for converting an output voltage from the lighting circuit and applying the voltage to the internal electrode and the external electrode of each arc tube. In the arc tube, the voltage conversion means applies voltages of different polarities to the internal electrode and the external electrode, and applies voltages of the same polarity and different magnitudes to the internal electrodes. The voltage conversion means adjusts the position of the dark portion generated during light emission of the arc tube to a desired position by controlling the difference between the voltages applied to the respective internal electrodes of the arc tube.

  According to the present invention, it is possible to easily control the position of the central dark portion generated in the center portion of the lamp when a voltage is applied from a single high-frequency power source to the internal electrode and the external electrode to light the lamp. . For this reason, for example, when a discharge device to which the idea of the present invention is applied is used as a planar light source device such as a backlight, dark portions generated at the time of light emission can be dispersed in a planar manner, thereby greatly reducing light output unevenness. It becomes possible.

  Hereinafter, embodiments of a discharge lamp device and the like of the present invention will be described with reference to the accompanying drawings. In the following description, the same parts may be denoted by the same reference numerals and redundant description may be omitted.

(Embodiment 1)
First, an example of a discharge lamp device according to the present invention will be described. FIG. 1A shows the configuration of the discharge lamp device of the present embodiment. FIG. 1B is a cross-sectional view taken along line I-I in FIG.

  The light source device 10 includes a lighting circuit 13, a voltage conversion unit 13 </ b> F, and an arc tube 20. The arc tube 20 includes a plurality of internal electrodes 21 disposed therein and external electrodes 22 disposed outside. A lead 24 is connected to the internal electrode 21.

  Within the arc tube 20, a plurality of internal electrodes 21 are sealed apart from each other. FIG. 1A shows a case where two internal electrodes are sealed as an example. It is preferable to arrange the internal electrodes 21 at both ends of the arc tube 20 as shown in the figure, because the entire arc tube can be lit with the smallest number of internal electrodes. In the following, for convenience of explanation, an example in which the number of internal electrodes is two will be described.

  The arc tube 20 is formed of a translucent material, for example, borosilicate glass. The arc tube 20 may be formed of quartz glass, soda glass, or lead glass. The outer diameter of the glass tube used for the arc tube 20 is usually about 1.2 mm to 15 mm. Further, the distance between the outer surface and the inner surface of the glass tube, that is, the thickness of the glass tube is usually about 0.2 mm to 1.0 mm. The arc tube 20 is not limited to a linear shape, and may have other shapes. For example, it may be L-shaped, U-shaped or rectangular.

  The arc tube 20 is sealed, and a discharge medium is sealed therein (the same applies to the following embodiments). As a discharge medium used in the discharge lamp device 10, a rare gas can be used. As the rare gas, at least one gas selected from krypton gas, argon gas, helium gas, and xenon gas can be used. In particular, the wavelength of ultraviolet rays emitted from xenon gas is close to the wavelength of ultraviolet rays emitted from mercury. For this reason, it is preferable to use xenon gas as a rare gas because there is an advantage that the same phosphor as that of a fluorescent lamp using mercury can be used. The discharge medium may further contain mercury in addition to the rare gas. However, when the discharge medium does not contain mercury, it is possible to prevent the light emission efficiency from changing due to a change in mercury vapor pressure accompanying a change in ambient temperature. The discharge medium described above can also be applied as a discharge medium in the following embodiments.

  As shown in FIG. 1B, a phosphor layer 23 is formed on the inner surface of the arc tube 20. The phosphor layer 23 is formed in order to convert the wavelength of light emitted from the discharge medium. By changing the material of the phosphor layer 23, light of various wavelengths can be obtained. For example, white light and red, green, and blue (RGB) light can be obtained. The phosphor layer 23 can be formed of a material generally used for a discharge lamp.

  The arc tube 20 may include a dielectric layer (for example, a resin layer) disposed on the outer surface thereof. An example of such an arc tube 20 is shown in FIG. The arc tube 20 includes a tube 20a and a dielectric layer 20b formed on the outer surface of the tube 20a. The tube 20a is made of, for example, borosilicate glass. For the dielectric layer 20b, for example, a multilayer film made of polyester resin, or a thin film made of titanium oxide or silicon oxide can be used. When the dielectric layer is formed on the surface of the glass tube, the thickness is usually preferably about 0.5 μm to 100 μm.

  The internal electrodes 21 are formed at both ends of the arc tube 20. The internal electrode 21 can be formed of a metal such as tungsten or nickel. The surface of the internal electrode 21 may be covered with a metal oxide layer such as cesium oxide, magnesium oxide, or barium oxide. By using such a metal oxide layer, the lighting start voltage can be reduced and electrode deterioration due to ion bombardment can be prevented. The surface of the internal electrode 21 may be covered with a dielectric layer (for example, a glass layer). FIG. 2B shows a cross-sectional view of the internal electrode 21 including a metal electrode 21a and a dielectric layer 21b formed so as to cover the metal electrode 21a. By using such a dielectric layer, current during discharge can be suppressed. As a result, it is possible to suppress the continuous flow of current during discharge and to stabilize discharge.

  The external electrode 22 is formed outside the arc tube 20. The external electrode 22 can be formed of a conductive material. For example, the external electrode 22 may be formed of a metal such as copper, aluminum, or phosphor bronze, or may be formed of a metal paste containing a metal powder (for example, silver powder) and a resin.

  The external electrode 22 is formed outside the arc tube 20 and may be discharged, and its position and area are not limited. In other words, it may or may not be in direct contact with the outer surface of the arc tube. FIG. 2C shows a cross-sectional view when the arc tube 20 and the external electrode 22 are spaced from each other with a gap. In this way, a gap is provided, and the distance between the arc tube 20 and the external electrode 22 is set such that the electric field strength applied to the gap does not cause dielectric breakdown of the air. Corona discharge in a minute space can be prevented, and generation of ozone can be prevented. In addition, even in the case of contact, it goes without saying that the external electrode may be spirally arranged in the circumferential direction of the arc tube 20.

  The arrangement and quantity of the external electrodes 22 are not limited as long as they are electrically connected by lead wires or the like and have the same potential. FIG. 3A shows an example in which the external electrode 22 is divided into two in the tube axis direction, and FIG. 3B shows an example in which the external electrode 22 is divided into a plurality of parts and spaced apart. When the external electrode 22 is divided into a plurality of parts, it is possible to suppress the discharge from contracting to the inner wall of the arc tube in the vicinity of the external electrode 22, so that the light emission efficiency can be improved.

  A more specific configuration example of the discharge lamp device 10 will be described. Here, the arc tube 20 has an outer diameter of 3.0 mm, an inner diameter of 2.0 mm, and a length of 350 mm, for example. The arc tube 20 is coated with a three-wavelength emission type rare earth phosphor used for a general fluorescent lamp as a phosphor layer. The internal electrodes 21 are enclosed one by one at both ends of the arc tube. For example, the outer diameter is 1.5 mm, the inner diameter is 1.3 mm, and the length is 5 mm. The width of the external electrode 22 is 1.5 mm, and is arranged linearly on the entire outer surface of the arc tube in the tube axis direction. Inside the arc tube, a mixed gas of xenon gas and argon gas is sealed so that the pressure is about 21 kPa.

  In the discharge lamp device 10, discharge is generated by applying a voltage from the lighting circuit 13 to the internal electrode 21 and the external electrode 22 through the voltage conversion means 13F, and the discharge medium is excited. The excited discharge medium emits ultraviolet rays when transitioning to the ground state. This ultraviolet light is converted into visible light by the phosphor layer 23 and emitted from the arc tube 20.

Hereinafter, the voltage applied between the internal electrode 21 and the external electrode 22 will be described.
The voltage conversion unit 13F applies the same polarity voltage to each of the plurality of internal electrodes 21, but applies different polarities to the internal electrode 21 and the external electrode 22. This is for preventing discharge between the internal electrodes 21 and causing discharge only between the external electrode 22 and each internal electrode 21. In this embodiment, the potential of the external electrode 22 is set as a reference potential.

  Furthermore, the voltage conversion means 13F varies the magnitude of the voltage applied to each internal electrode 21 in one arc tube 20. And the voltage conversion means 13F controls the position of the dark part produced in the arc_tube | light_emitting_tube 20 to a desired position by adjusting the difference between the voltages applied to each internal electrode 21. FIG.

  The voltage applied between the internal electrode 21 and the external electrode 22 may be a sine wave or a rectangular wave, and the polarity may or may not change. When mercury is not contained in the arc tube 20, that is, when the discharge medium is only a rare gas, the external electrode 22 is grounded and a rectangular wave voltage that does not change the voltage polarity is applied to the internal electrode 21. It is preferable to do.

  Now, consider the case where the lighting circuit 13 outputs an output voltage V1 as shown in FIG. In the example shown in FIG. 4A, the applied voltage to the internal electrode 21 is modulated between 0 volts and the positive voltage V1. The value of the ratio (T1 / T2) between the time T1 for applying the voltage V1 and the period T2 of the rectangular wave is preferably about 0.15 to 0.5. Moreover, the frequency of a rectangular wave is the range of 10 kHz-60 kHz, for example. FIG. 4B shows a current flowing between the two electrodes 21 and 22 when the voltage shown in FIG. 4A is applied. As shown in the figure, a current corresponding to the differential waveform of the applied voltage flows between the internal electrode 21 and the external electrode 22.

  A configuration example of the lighting circuit 13 is shown in FIG. A lighting circuit 13 is connected between the internal electrode 21 and the external electrode 22 through voltage conversion means 13F. The external electrode 22 is normally connected to the ground (reference potential point). The lighting circuit 13 includes an AC power supply 13a, a rectifier circuit 13b, a smoothing circuit 13c, a booster circuit 13d, and a switching circuit 13e. A general circuit can be used for these circuits. The AC voltage generated by the AC power supply 13a is converted into a DC positive voltage by the rectifier circuit 13b. The rectified voltage is smoothed by the smoothing circuit 13c and boosted by the boosting circuit 13d. The boosted voltage is applied for a predetermined time T1 by the switching circuit 13e. In this way, a rectangular wave voltage is output from the lighting circuit 13.

  The rectangular wave voltage V1 output from the lighting circuit 13 is modulated only by the voltage peak value through the voltage conversion means 13F as shown in FIG. 5B. That is, the positive voltage V1 is converted into the positive voltage V2 and the voltage V3 with reference to 0 volt, but the value of the ratio (T1 / T2) between the time T1 for applying the voltages V2 and V3 and the period T2 of the rectangular wave is It is not different from the original voltage V1. In this way, the rectangular wave voltages V2 and V3 are applied from the voltage conversion means 13F to each internal electrode 21. At this time, either the voltage V2 or the voltage V3 may be the same as the voltage V1.

  FIG. 5A also shows a specific configuration example of the voltage conversion unit 13F. The arc tube 20 connected to the discharge lamp device 10 has a barrier discharge structure through a dielectric, which is a structure similar to a capacitor. Therefore, by connecting capacitors C1 and C2 having different capacities in series to the internal electrode 21 of the arc tube 20 as the voltage conversion means 13F as shown in FIG. 5A, the divided voltages V2 and V3 are respectively Applied to the internal electrode 21. Alternatively, a capacitor may be connected only to at least one internal electrode, and the divided voltage V2 and the undivided voltage V1 may be applied to each internal electrode. As described above, it is preferable to use a capacitor as the voltage conversion unit 13F. However, other circuits may be used as long as the voltage applied to each internal electrode 21 can be varied.

  FIG. 6 shows the relationship between the capacitance of the capacitor C1 and the position of the dark portion generated in the arc tube 20 when the voltage conversion means 13F in which the capacitor C1 is inserted in series only with respect to one of the internal electrodes is used. In FIG. 6, the voltage peak value V1 output from the lighting circuit 10 is 2.0 kV, and the ratio (T1 / T2) between the time T1 to be applied and the period T2 of the rectangular wave is 0.5, and the period T2 The frequency was 40 kHz. As a result, as the capacitance of the capacitor C1 decreases, the voltage applied to the internal electrode on the capacitor C1 insertion side decreases, so the dark portion moves toward the internal electrode on the capacitor C1 insertion side. In the present embodiment, the moving amount of the dark portion is 5 mm from the center of the arc tube when the capacitance of the capacitor C1 is 2005 pF. there were.

Hereinafter, a light source device using the discharge lamp device 10 will be described.
FIG. 7 shows a configuration example of the light source device 11 when a plurality of the discharge lamp devices 10 are arranged in parallel to form a flat backlight. FIG. 8 is a cross-sectional view taken along line II-II in FIG. FIG. 8 also shows the diffusion plate 63 and the liquid crystal panel 70. 7 and 8, the phosphor layer is omitted. The liquid crystal panel 70 and the light source device 11 constitute a liquid crystal display device.

  The light source device 11 of FIG. 7 includes an arc tube 20, an internal electrode 21, an external electrode 22, a lighting circuit 13, and voltage conversion means 13F.

  The external electrode 22 is formed on the outer surface of the arc tube 20. The external electrode 22 can be formed of a metal paste or a conductive resin. The plurality of arc tubes 20 are supported by the support member 62 in parallel on the reflection plate 25. One internal electrode 21 is enclosed at each end of the arc tube 20. The reflection plate 25 surrounds the arc tube 20 in a box shape and functions to increase the incident efficiency of light from the arc tube 20 to the diffusion plate 63.

  The external electrode 22 may be freely changed in width, length, and area depending on necessary optical characteristics. If the external electrodes 22 are at the same potential, for example, they may be divided / separated in the longitudinal direction of the arc tube, or may be spirally arranged.

  In the light source device 11, discharge is generated by applying a voltage from the lighting circuit 13 between the internal electrode 21 and the external electrode 22 through the voltage conversion means 13F, and the discharge medium is excited. The excited discharge medium emits ultraviolet rays when transitioning to the ground state. This ultraviolet light is converted into visible light by the phosphor layer 23 and emitted from the arc tube 20.

  As shown in FIG. 8, the light emitted from the arc tube 20 is emitted almost uniformly from the surface 63 a through the diffusion plate 63 and irradiates the liquid crystal panel 70. The diffusion plate 63 can be formed of, for example, a milky white resin. Further, on the surface 63a of the diffusion plate 63, a diffusion sheet or a lens sheet may be arranged depending on the use situation.

  For example, as shown in FIG. 5A, the voltage conversion means 13F is composed of a capacitor connected in series with the internal electrode 21 and the external electrode 22 at both ends of the arc tube.

  When the conventional voltage conversion means 13F is not used, the same voltage is applied to each internal electrode of the arc tube 20, so that the center in the longitudinal direction of the arc tube is shown in FIG. A dark portion X occurs in the portion. By overlapping the positions of the dark portions X, the light output projected from the surface 63a of the diffusing plate 63 becomes a non-uniform light output in which dark portions are generated linearly.

  In order to solve this problem, in this embodiment, a voltage applied to one internal electrode and a voltage applied to another internal electrode in each arc tube 20 by a capacitor inserted in series between the lighting circuit 13 and the arc tube 20. And the voltage difference is adjusted as appropriate. Thereby, the position of the dark part X generated in each arc tube 20 is controlled. That is, by making the position of the dark part generated between adjacent arc tubes different, the position of the dark part X is dispersed as a whole surface as shown in FIG. The light output projected from the surface 63a is uniform.

  In addition, according to the configuration of the present embodiment, even in the case of a lamp design using a single lighting circuit, the voltage can be adjusted only by the capacity of a capacitor to be inserted, so that the control is easy. It is possible to provide an inexpensive light source device with uniform light output without changing the above.

(Embodiment 2)
In the present embodiment, another example of the light source device according to the present invention will be described.
FIG. 10 shows another configuration of the light source device. FIG. 11 is a cross-sectional view taken along line XX in FIG. FIG. 11 also shows the liquid crystal panel 70. Further, FIG. 12 shows a configuration (cross-sectional view) of a light source device of another example. In FIG. 10, FIG. 11, and FIG. 12, illustration of the phosphor layer is omitted.

  The light source device 12 shown in FIG. 10 includes a light guide plate 60, an arc tube 20, an internal electrode 21, an external electrode 22, a lighting circuit 13, and voltage conversion means 13F.

  The external electrode 22 is formed on the outer surface of the arc tube 20. The external electrode 22 can be formed of a metal paste or a conductive resin. The arc tube 20 has an L shape and is supported by a support member 62. One internal electrode 21 is enclosed at each end of the arc tube 20. The arc tube 20 is disposed on the side surface of the light guide plate 60. The reflection plate 25 surrounds the arc tube 20 in a U-shape and functions to increase the light incident efficiency from the arc tube 20 to the light guide plate 60.

  The external electrode 22 may be freely changed in width, length, and area depending on necessary optical characteristics. The external electrode 22 may be composed of a plurality of electrodes having the same potential. For example, the external electrode 22 may be divided in the axial direction in the longitudinal direction of the arc tube and may be spaced apart or may be spirally disposed.

  In the light source device 12, discharge is generated by applying a voltage from the lighting circuit 13 between the internal electrode 21 and the external electrode 22 through the voltage conversion means 13F, and the discharge medium is excited. The excited discharge medium emits ultraviolet rays when transitioning to the ground state. This ultraviolet light is converted into visible light by the phosphor layer 23 and emitted from the arc tube 20.

  The light emitted from the arc tube 20 is emitted almost uniformly from the surface 60 a through the light guide plate 60. The light guide plate 60 can be formed of, for example, a transparent resin. On the back surface 60b of the light guide plate 60, irregularities are formed in order to make the emitted light uniform. A reflective layer 61 is formed on the back surface 60b. The reflective layer 61 can be formed of, for example, titanium oxide, metal, resin, or the like. In addition, a diffusion sheet or a lens sheet may be arranged on the surface 60a of the light guide plate 60 according to the use situation.

  For example, as shown in FIG. 5A, the voltage conversion means 13F includes capacitors C1 and C2 connected in series with the internal electrode 21 and the external electrode 22 at both ends of the arc tube.

  In the light source device 12 of FIG. 10, the capacities of the capacitors C1 and C2 of the voltage conversion unit 13F are set so that the dark portion X generated in the arc tube 20 is located at the L-shaped bent portion of the arc tube 20. The bent portion of the L-shaped arc tube 20 is located in the vicinity of the corner of the side surface of the light guide plate 60. At the corner of the side surface of the light guide plate 60, the amount of light incident on the light guide plate is minimized (that is, the light incident efficiency is minimized). Therefore, by controlling the position of the dark part X to be positioned at the L-shaped bent part of the arc tube 20, the influence of the light output by the dark part X is minimized, and the light output projected from the surface 60a of the light guide plate 60 is It becomes uniform. Therefore, a light source device with uniform light output is possible.

  An example of specific specifications for the light source device 12 will be described. The light guide plate 60 can be formed of an acrylic resin, and the size thereof can be 160 mm × 93 mm. The L-shaped arc tube 20 can have a length of 252 mm, an outer diameter of 2.6 mm, and an inner diameter of 2.0 mm. As the discharge medium, a mixed gas of xenon gas and argon gas (pressure: about 21 kPa) can be used. The internal electrodes 21 are sealed one by one at both ends of the arc tube. For example, the outer diameter can be 1.5 mm, the inner diameter is 1.3 mm, and the length is 5 mm. In the arc tube, a three-wavelength emission type rare earth phosphor used in a general fluorescent lamp can be applied as a phosphor layer. The width of the external electrode is 1.5 mm and can be arranged over almost the entire length of the arc tube. The capacitance value of the capacitor C1 of the voltage conversion means 13F is 75 pF and can be inserted into the internal electrode 21 on the short side of the L-shaped arc tube 20. A capacitor is not connected to the internal electrode 21 on the long side of the L-shaped arc tube 20, and the output voltage of the lighting circuit 13 can be applied to the internal electrode 21 as it is.

  When the light source device 12 is used as a liquid crystal display device, the liquid crystal panel 70 is disposed on the light guide plate 60 as shown in FIG. 11 (the same applies to the following light source devices).

  The reflection plate 25 may be formed of a conductive material such as aluminum, and may have both an external electrode function and a reflection plate function. FIG. 12 shows a configuration example of a light source device having an electrode having such a reflector function.

  In FIG. 12, the light source device 13 includes a light guide plate 60, an arc tube 20, an internal electrode 21, and a reflection plate external electrode 26.

  The reflector-equipped external electrode 26 is formed on the outer surface of the arc tube 20. The arc tube 20 and the reflector-equipped external electrode 26 are arranged on the side surface of the light guide plate 60 with a gap, for example, between them. By spacing the arc tube 20 and the external electrode 26 with a gap or the like, corona discharge in a minute space between the arc tube 20 and the external electrode 26 can be prevented, and generation of ozone can be prevented.

  FIG. 13 shows an example of a light source device in which the L-shaped arc tube 20 is replaced with a U-shaped arc tube as another example of the light source device. In the light source device 120 of FIG. 13, the internal electrodes 21 of the arc tube 20 are encapsulated one by one at both ends of the U-shaped arc tube 20, and the inner electrode 21 is also directed in the end direction toward the center of the arc tube. Only one is enclosed.

  In the configuration of FIG. 13, the output voltage from the lighting circuit 13 is applied to each internal electrode 21 through the voltage conversion means 13F. When lit in this state, the dark part is generated in the same state as the L-shaped arc tube divided into two at the center of the arc tube. At this time, the set value of the capacitor of the voltage converting means 13F is made the same as the set value in the case of an L-shaped arc tube obtained by dividing the U-shaped arc tube 20 into two equal parts, and the internal electrodes 21 at both ends of the arc tube 20 are connected. By lighting at the same potential, it is possible to control the dark portion X to be positioned at the bent portion of the U-shaped arc tube 20, and the dark portion X is positioned near the position where the light incident efficiency of the light guide plate 60 is the lowest. Therefore, a light source device that can obtain a highly uniform light output from the surface 60a of the light guide plate 60 can be realized.

  FIG. 14 shows still another example of the light source device. The light source device of FIG. 14 includes a light guide plate 60 having a wedge-shaped cross section when cut along a plane perpendicular to the longitudinal direction. Two L-shaped arc tubes 20 are arranged on the side surface of the light guide plate 60. Since the center in the width direction of the side surface in the width direction of the light guide plate 60 is the position where the light incident efficiency is lowest, the dark portion X of the arc tube 20 is the center portion in the width direction of the side surface in the width direction of the light guide plate 60. It is controlled to be located in the vicinity. Thereby, the influence of the dark part X with respect to the light output from the surface 60a of the light guide plate 60 can be minimized, and a uniform light output can be obtained.

  The embodiments of the present invention have been described with reference to the examples. However, it is needless to say that the present invention is not limited to the above embodiments and can be applied to other examples based on the technical idea of the present invention. .

  The light source device of the present invention is a discharge lamp device and a light source device including an arc tube in which a discharge medium is enclosed and an electrode for exciting the discharge medium, and is useful as a backlight light source. Useful for backlight.

(A) The side view of an example of the discharge lamp apparatus of this invention, (b) Sectional drawing of an example of the discharge lamp apparatus of this invention. (A) is sectional drawing of the other example of a discharge lamp apparatus, (b) Sectional drawing of the other example of an internal electrode, (c) Sectional drawing of the other example of an external electrode. Sectional drawing of the other example of the discharge lamp apparatus shown in FIG. (A) The figure which shows an example of the voltage applied to the discharge lamp apparatus of this invention, and the figure which shows the electric current which flows between electrodes in the case of (b) (a). (A) The circuit diagram which shows the specific structural example of the voltage conversion means in the discharge lamp apparatus of this invention, (b) The figure which showed operation | movement of the voltage conversion means. 6 is a graph showing changes in dark portion position when a capacitor is used as the voltage conversion means in the first embodiment. The figure which shows the structure of an example of the light source device of this invention. Sectional drawing of the light source device shown in FIG. (A) The figure explaining how the dark part was concentrated and distributed in the center in the light source device shown in FIG. 7, and (b) The figure explaining how the dark part was distributed and distributed in the light source apparatus shown in FIG. . The figure which shows the structure of the other example of the light source device of this invention (an L-shaped light emission lamp | ramp is included). Sectional drawing of the light source device shown in FIG. Sectional drawing which shows the structure of the further another example of the light source device of this invention (an electrode with a light emission plate function is included). The figure which shows the structure (a U-shaped light emission lamp | ramp is included) of the other example of the light source device of this invention. The figure which shows the structure (a wedge cross-section light guide plate is included) of the further another example of the light source device of this invention. The block diagram of the conventional discharge lamp. The block diagram of another example of the conventional discharge lamp.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Discharge vessel 4 Introductory line 6 High frequency power supply 10 Discharge lamp device 11, 12, 13, 120 Light source device 9a, 9b, 13 Lighting circuit 13F Voltage conversion means 20 Arc tube 20a Tube 20b Dielectric layer 2, 8a, 8b, 21 Inside Electrode 21a Metal electrode 21b Dielectric layers 3, 7a, 7b, 22 External electrode 23 Phosphor layer 24 Lead 25 Reflector plate 26 Reflector plate external electrodes 60, 60a, 60b Light guide plate 61 Reflective layer 62 Support members 63, 63a Diffuser plate X Dark part 70 Liquid crystal panel DL Discharge lamp

Claims (7)

A plurality of arc tubes each having at least two internal electrodes provided opposite to each other and an external electrode, in which a discharge medium is enclosed;
A light guide plate that receives and propagates light from the plurality of arc tubes;
A lighting circuit for generating a voltage for applying a voltage to the inner electrode and the outer electrode of the arc tube;
Voltage conversion means for converting the output voltage from the lighting circuit and applying it to the internal electrode and the external electrode of each arc tube;
The plurality of arc tubes are arranged in parallel,
In each arc tube, the voltage conversion means applies a voltage having a different polarity to the internal electrode and the external electrode, applies a voltage having the same polarity and a different magnitude to each of the internal electrodes, A light source device characterized by controlling a difference in voltage applied to each internal electrode of each arc tube so that positions of dark portions generated in the arc tube are scattered and distributed. A plurality of arc tubes each having at least two internal electrodes provided opposite to each other and an external electrode, in which a discharge medium is enclosed;
A light guide plate that receives and propagates light from the plurality of arc tubes;
A lighting circuit for generating a voltage for applying a voltage to the inner electrode and the outer electrode of the arc tube;
Voltage conversion means for converting the output voltage from the lighting circuit and applying it to the internal electrode and the external electrode of each arc tube;
The arc tube has a bent portion, and is disposed on the side of the light guide plate so that the bent portion is positioned near the corner of the light guide plate,
In each arc tube, the voltage conversion means applies a voltage having a different polarity to the internal electrode and the external electrode, applies a voltage having the same polarity and a different magnitude to each of the internal electrodes, and the arc tube The light source device is characterized in that the difference in voltage applied to each internal electrode of the arc tube is controlled so that a dark part of the arc occurs at the bent part.   The light source device according to claim 1, wherein the voltage conversion unit includes a capacitor connected in series between the lighting circuit and the internal electrode.   The light source device according to claim 1, wherein the at least two internal electrodes are provided at both ends of the arc tube.   The light source device according to claim 1, wherein the external electrode is grounded. LCD panel,
A liquid crystal display device comprising: the light source device according to claim 1 that supplies illumination light to the liquid crystal panel. An arc tube having at least two internal electrodes provided opposite to each other and an external electrode, in which a discharge medium is enclosed;
A lighting circuit for generating a voltage for applying a voltage to the inner electrode and the outer electrode of the arc tube;
Voltage conversion means for converting the output voltage from the lighting circuit and applying it to the internal electrode and the external electrode of each arc tube;
In the arc tube, the voltage conversion means applies a voltage of different polarity to the internal electrode and the external electrode, applies a voltage of the same polarity and different magnitude to each of the internal electrodes,
A discharge lamp device characterized by adjusting a position of a dark portion generated during light emission of the arc tube by controlling a difference between voltages applied to respective internal electrodes of the arc tube.

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