JP2009301785A - Lighting device and lighting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress power consumption when turning on a cold cathode type fluorescent lamp. <P>SOLUTION: This lighting device 1 includes a heater 14 provided at the outside center of the cold cathode type lamp 11 having an anode and a cathode and shorter than the lamp 11 for heating the lamp 11. In addition, the lighting device 1 includes inverters 12, 13 for applying starting voltage VS between the anode and the cathode provided at both ends of the lamp 11. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lighting device and a lighting method.

  In recent years, a liquid crystal display has been widely used as a flat display. As a light source for a backlight of a liquid crystal display, a CCFL (Cold Cathode Fluorescent Lamp) that generates a cold cathode arc discharge by applying a high voltage to the cathode instead of heating the cathode using a filament or the like is used. Often used.

  In the CCFL, a luminescent material such as mercury is enclosed in a glass tube or the like. If the temperature of the encapsulated luminescent material is low, the pressure in the glass tube will be low, and the luminous efficiency of the CCFL will be reduced.

  When generating a high voltage to be applied to the CCFL having the above-described configuration, a transformer capable of boosting the voltage to an arbitrary boost value is generally used.

  However, the “starting voltage” required to start lighting the CCFL is greatly different between the normal temperature and a low temperature (for example, 0 ° C. or less) at a lower temperature than the normal temperature. Therefore, when the CCFL is turned on using a transformer whose boost value is designed based on the starting voltage at room temperature, there is a possibility that only a portion near the electrode in the CCFL can be turned on at a low temperature. There is a problem.

  In order to avoid such a state, it is conceivable to use a transformer having a boosting mechanism capable of boosting the boosted value to a starting voltage at a low temperature or higher.

  Further, in the technology for boosting the boost value to a start voltage at a low temperature or higher, the amount of heat generated in the transformer increases as the boost value increases.

  Furthermore, in the technology for boosting the boost value to a starting voltage at a low temperature or higher, there is a problem that the size of the lighting device increases as the size of the transformer increases.

  In order to avoid increasing the boosted value of the transformer, a technique has been considered in which the temperature of the luminescent material in the CCFL is increased to improve the luminous efficiency when the CCFL is turned on.

  For example, a liquid crystal display device is disclosed in which a heater is provided outside a lamp cover that covers the CCFL, and the CCFL is heated by the heater, thereby increasing the temperature inside the CCFL even in a low temperature atmosphere and shortening the time until the CCFL is lit. (For example, refer to Patent Document 1).

Further, for example, there is provided a low-voltage discharge device that improves the heating efficiency of the CCFL by further providing a heat insulating material that covers the heater in the low-voltage discharge device in which the heater is disposed along substantially the entire circumference of the annular CCFL. (For example, refer to Patent Document 2).
Japanese Patent Laid-Open No. 08-036177 Japanese Patent Laid-Open No. 08-017401

  According to the technique disclosed in Patent Document 1, the temperature inside the CCFL rises and a discharge path is easily formed. However, since the heater heats the CCFL through the lamp cover, there is a problem that it may not be able to sufficiently contribute to the formation of the discharge path.

  Further, according to the techniques disclosed in Patent Documents 1 and 2, the size of the heater is configured to be approximately the same as the entire outer shape of the CCFL. For this reason, there is a problem that it is difficult to reduce the size of the lighting device for CCFL lighting.

  Furthermore, according to the techniques disclosed in Patent Documents 1 and 2, since the heating element included in the heater is also arranged corresponding to the entire CCFL, the power consumption of the lighting device when the CCFL is lit cannot be reduced. There is also a problem.

  An object of this invention is to provide the lighting device and lighting method which solve the subject mentioned above.

  In order to solve the above problems, a lighting device of the present invention is a lighting device for lighting a cold cathode type light emitting object having an anode and a cathode, and is provided in the center outside the light emitting object. And a heater that heats the light emitting object shorter than the length of the light emitting object, and an inverter that applies a starting voltage for lighting the light emitting object between the anode and the cathode.

  In order to solve the above problems, a lighting method of the present invention is a lighting method in a lighting device for lighting a cold cathode type light emitting object having an anode and a cathode, and is provided at the center outside the light emitting object. A process of heating the light emitting object with a heater shorter than the length of the light emitting object, and a process of applying a starting voltage for lighting the light emitting object between the anode and the cathode; Have

  According to the present invention, in a lighting device using a double-sided high-voltage inverter that applies a starting voltage having a high voltage value between an anode and a cathode of a lamp, a heater is disposed at the center of the lamp.

  As described above, since the heater is arranged not corresponding to the entire lamp but to a part near the center of the lamp, the size of the heater can be reduced, and the lighting device can be easily reduced in size.

  In addition, according to the present invention, the size of the heater can be further reduced, so that it is possible to reduce the power consumption of the lighting device when the lamp is lit.

  Hereinafter, a lighting device (including a lighting method) according to an embodiment of the present invention will be described.

  First, the configuration of the lighting device 1 will be described.

  As shown in FIG. 1, the lighting device 1 includes a lamp 11, inverters 12 and 13, a heater 14, and lamp caps 15 and 16.

  The lamp 11 is a cold cathode type CCFL and is a “light emitting object”. Note that the number of lamps 11 that the lighting device 1 is to emit light may be arbitrary.

  As shown in FIG. 2, the lamp 11 includes a glass tube 111, a phosphor coating 112, an anode 113, and a cathode 114.

  The glass tube 111 is made of a material such as quartz glass and has a predetermined shape (for example, a cylindrical shape).

Inside the glass tube 111, mercury which is a luminescent substance and at least one kind of rare gas (for example, argon) are sealed. The rare gas is enclosed for the purpose of improving the luminous efficiency of the lamp 11 (excitation efficiency of the luminescent substance by secondary electrons e _S described later).

  In addition, a phosphor coating 112 is formed on the inner surface of the glass tube 111. The phosphor coating 112 emits visible light when irradiated with ultraviolet rays from mercury atoms enclosed in the glass tube 111.

  A pair of discharge electrodes, an anode 113 and a cathode 114, are provided at both ends of the glass tube 111 in the longitudinal direction.

The anode 113 serves to collect the secondary electrons e _S emitted from the cathode 114.

  The cathode 114 is made of, for example, mercury having a lower boiling point than a material (for example, tungsten) used as an emitter in a hot cathode fluorescent lamp.

When the rare gas ions GI enclosed in the glass tube 111 collide with the cathode 114, secondary electrons e _S are emitted from mercury atoms constituting the cathode 114.

In other words, the cathode 114 plays a role of releasing secondary metal e _S necessary for lighting the lamp 11 by releasing mercury metal vapor.

Due to the collision between the secondary electrons e _S and the rare gas atoms GA, a discharge path for guiding the secondary electrons e _S is formed between the anode 113 and the cathode 114, and the lamp 11 is turned on.

  The inverters 12 and 13 shown in FIG. 1 are arranged to face each other with the lamp 11 in between.

  Each of the inverters 12 and 13 is composed of, for example, a power supply circuit including a transformer (for example, a separately excited resonance type power supply circuit), and converts a DC voltage into an AC voltage.

  The inverters 12 and 13 are connected to the anode 113 or the cathode 114 of the lamp 11, respectively, and serve to turn on the lamp 11 by supplying an alternating voltage (starting voltage VS) boosted by a transformer to the anode 113 or the cathode 114. Fulfill.

  The “starting voltage VS” here is a voltage having a voltage value necessary for starting the lamp 11 to start lighting.

  Inverters 12 and 13 may convert the commercial power into a DC voltage once by a rectifier circuit and convert the DC voltage into an AC voltage having a frequency higher than that of the commercial power.

  In the following, a case where the inverters 12 and 13 cooperate to apply the starting voltage VS between the anode 113 and the cathode 114 will be described as an example. In this case, the inverter 12 functions as a master inverter that controls the frequency of the starting voltage VS output from the inverter 13 that functions as a slave inverter. The inverter 12 outputs a control signal SS for controlling the frequency of the starting voltage VS to the inverter 13.

  The heater 14 is disposed in the vicinity of the outside of the central portion of the lamp 11. The heater 14 includes a heating element that generates heat using electric energy supplied from the outside, and plays a role of heating the vicinity of the central portion of the lamp 11.

  In the lighting device 1 of the present invention, the position at which the heater 14 is disposed greatly affects the lighting start characteristics of the lamp 11. Hereinafter, the positional relationship between the lamp 11 and the heater 14 will be described in detail.

  When the lamp 11 is lit by the double-sided high-pressure method, the discharge path in the center portion of the lamp 11 is most difficult to be formed. Therefore, in the lighting device 1 of the present invention, it is preferable to arrange the heater 14 at the center of the lamp 11.

  More specifically, when the total length of the lamp 11 in the axial direction is 50 cm, it is most preferable to arrange the heater 14 at a position 25 cm from the end of the lamp 11.

  Further, the length of the heating element included in the heater 14 is configured to be shorter than the total length of the lamp 11 in order to reduce power consumption when the lamp 11 is turned on. Under such a configuration, in order to further obtain the effect of improving the lighting start characteristics of the lamp 11, the ratio of the size of the heating element of the heater 14 to the total length of the CCFL may be, for example, about 20%. As described above, the center position of the heater 14 and the center position of the lamp 11 are most preferably matched.

  Note that the arrangement between the outer surface of the lamp 11 and the heating element of the heater 14 may be arranged so that the heating element of the heater 14 does not directly touch the outer surface of the lamp 11.

  The lamp cap 15 or 16 has a holding mechanism for holding the anode 113 or the cathode 114 included in the lamp 11, and plays a role of attaching the lamp 11 to the lighting device 1.

  The lamp cap 15 has a terminal that contacts the anode 113, and connects the anode 113 and the inverter 12. The lamp cap 16 has a terminal that contacts the cathode 114, and connects the cathode 114 and the inverter 13.

  Next, an operation in which the lighting device 1 having the above configuration lights the lamp 11 will be described.

  In a general lighting device that does not include the heater 14, when the lamp 11 is lit at a low temperature, the starting voltage applied between the anode 113 and the cathode 114 by the high-voltage inverters 12 and 13 on both sides is low (for example, 0). If it is lower than the starting voltage value (° C. or lower), only a portion near the electrodes provided at both ends of the lamp 11 may be discharged. This is because the gas temperature of the rare gas atoms GA is low in the central portion of the lamp 11 and the pressure of the rare gas atoms GA is also low.

  In the lighting device 1 of the present invention, the heater 14 heats the vicinity of the central portion of the lamp 11. Due to the heating, the gas temperature of the rare gas atom GA inside the glass tube 111 in the vicinity of the central portion of the lamp 11 is increased. In addition, when the heater 14 overheats, it is preferable to heat the external surface temperature of the lamp 11 so as to rise to about 25 ° C., for example.

  As the gas temperature of the rare gas atom GA rises, the pressure of the rare gas atom GA also increases, that is, the kinetic energy of the rare gas atom GA is large.

  In the state where the lamp 11 is heated by the heater 11, the inverters 12 and 13 apply the starting voltage VS for lighting the lamp 11 between the anode 113 and the cathode 114. The starting voltage VS applied between the anode 113 and the cathode 114 may be the starting voltage value at room temperature in the lighting device 1 of the present invention.

In this case, an electric field is generated in the glass tube 111 by the starting voltage VS, and as shown in FIG. 3A, electrons originally present in the glass tube 111 before application of the starting voltage VS (hereinafter referred to as “initial electrons”). e ₀ ") is accelerated.

The accelerated initial electrons e ₀ collide with noble gas atoms GA having a large kinetic energy due to the heating of the heater 14 and ionize the noble gas atoms GA.

By the ionization, as shown in FIG. 3B, positive ionized rare gas ions GI and ionized electrons e _I (plasma) are generated inside the glass tube 111. This plasma serves as a “discharge path”, which is a path through which a discharge current flows in the glass tube 111.

Further, the rare gas ions GI are accelerated toward the cathode 114 and collide with the cathode 114. As a result of the collision, secondary electrons e _S are emitted from the cathode 114 as shown in FIG.

The secondary electrons e _S are accelerated toward the anode 113 by the starting voltage VS applied by the inverters 12 and 13, and collide with the rare gas atoms GA.

New rare gas ions GI are further generated by the collision between the secondary electrons e _S and the rare gas atoms GA. New rare gas ions GI collide with the cathode 114 and contribute to the emission of new secondary electrons e _S from the cathode 114.

Further, when the secondary electrons e _S shown in FIG. 3C collide with the mercury atoms HG enclosed in the glass tube 111, the mercury atoms HG are excited. When the excited mercury atom HG releases energy and returns to the ground state, ultraviolet rays are emitted. Then, the ultraviolet rays from the mercury atoms HG are applied to the phosphor coating 112, and visible light is emitted from the lamp 11.

  Note that once the lamp 11 is turned on, the lamp 11 is stably lit by self-heating. Thus, the operation of the lighting device 1 to turn on the lamp 11 is completed.

  As described above, according to the present invention, the lighting device 1 is configured to heat the vicinity of the central portion of the lamp 11 where the discharge path is difficult to be formed when the lamp 11 is lit.

Due to the heating, the temperature inside the glass tube 111 in the vicinity of the central portion of the lamp 11 increases the pressure of the glass tube 111 and the kinetic energy of the rare gas atoms GA increases. Therefore, secondary electrons e _S are easily emitted from the cathode 114.

Furthermore, by promoting the emission of secondary electrons e _S from the cathode 114, the ionization of the rare gas atoms GA by the secondary electrons e _S is also promoted. For this reason, a discharge path for the secondary electrons e _S is easily formed even in the central portion of the lamp 11.

  That is, cold cathode arc discharge is likely to occur not only in the vicinity of the end portion of the lamp 11 but also in the central portion of the lamp 11, and the lamp 11 can be easily lit normally.

  According to the present invention, the heater 14 is configured to heat the vicinity of the central portion of the glass tube 111. Therefore, the size of the heater 14 can be reduced, and the lighting device 1 can be easily reduced in size.

  In addition, according to the present invention, since the heating element included in the heater 14 is arranged corresponding to a part near the center of the glass tube 111 instead of the entire glass tube 111, the size of the heating element can be further reduced. Can do. Therefore, it becomes possible to reduce the power consumption of the lighting device 1 when the lamp 11 is lit.

  Various modifications can be made without departing from the scope of the present invention.

  The position where the heater 14 is disposed is not limited to the vicinity of the central portion of the lamp 11, and may be configured to be an arbitrary place where it is difficult for discharge to occur when the lamp 11 is turned on.

  Even when the outer shape of the glass tube 111 constituting the lamp 11 is other than a cylindrical shape (for example, an annular shape or a U shape), the lighting device 1 of the present invention can be used for lighting.

  When the outer shape of the lamp 11 is an annular shape, as illustrated in FIG. 4, a heater 14 for heating may be disposed corresponding to a place where the discharge is least likely to occur in the lamp 11.

  Furthermore, the lighting device 1 of the present invention is not limited to the case where the starting voltage VS is applied to the lamp 11 by the above-described double-sided high voltage method, but can also be applied to the case where the starting voltage VS is applied by the one-side high voltage method.

  In the one-side high voltage method, the starting voltage VS is applied to either the anode 113 or the cathode 114 included in the lamp 11 using either the inverter 12 or 13.

  In this case, discharge is least likely to occur at the end of the glass tube 111 on the electrode side (ground) to which the starting voltage VS is not applied among the anode 113 and the cathode 114.

  Therefore, for example, in the case where the starting voltage VS is applied to the lamp 11 from the anode 113 side, the heater 14 may be arranged near the end portion on the cathode 114 side included in the lamp 11 as shown in FIG.

It is a figure which shows the structure of the lighting device according to embodiment of this invention. It is a figure which shows the structure of the lamp | ramp shown in FIG. (A) It is a figure which shows the 1st state inside a lamp when a starting voltage is applied during the heating by a heater. (B) It is a figure which shows the 2nd state inside a lamp | ramp when a starting voltage is applied. (C) It is a figure which shows the 3rd state inside a lamp | ramp when a starting voltage is applied. It is a figure which shows an example of a structure of a lighting device in case the external shape of a lamp | ramp is an annular | circular shape. It is a figure which shows an example of a structure of a lighting device in case the application system of a starting voltage is a one side high voltage | pressure system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lighting device 11 Lamp 111 Glass tube 112 Phosphor film 113 Anode 114 Cathode 12, 13 Inverter 14 Heater 15, 16 Lamp cap

Claims (2)

A lighting device for lighting a light emitting object of a cold cathode type having an anode and a cathode,
A heater that is provided at the center of the outside of the light emitting object and that is shorter than the length of the light emitting object and that heats the light emitting object;
A lighting device comprising: an inverter that applies a starting voltage for lighting the light emitting object between the anode and the cathode. A lighting method in a lighting device for lighting a cold cathode type luminescent object having an anode and a cathode,
A process of heating the light emitting object with a heater that is provided in the center of the outside of the light emitting object and is shorter than the length of the light emitting object;
A lighting method comprising: applying a starting voltage for lighting the light emitting object between the anode and the cathode.

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