JP2009032453A - Lighting control method for hot-cathode discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain longer life of a lamp by restraining consumption of an emitter since a position of a cathode bright point on the emitter of a filament is forcibly moved continuously at designated speed when discharging a hot-cathode fluorescent lamp. <P>SOLUTION: In a lighting control method for a hot-cathode discharge lamp, a magnetic field generation device 13 each having a magnetic field generation source 12 is arranged on the outside of a fluorescent lamp 1 in the vicinity of a coil-shaped filament 8 located on both ends of the hot-cathode fluorescent lamp 1, and the magnetic field generation sources 12 are formed to repetitively make a reciprocating movement between two points at designated speed so as to be approximately parallel with the filament 8 and be approximately the same distance to the center position of the filament. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lighting control method for a hot cathode discharge lamp.

  There is a hot cathode fluorescent lamp as a thermionic emission type discharge lamp. The hot cathode fluorescent lamp has a (Ba / Sr / Ca) O in a coiled W (tungsten) wound in double, triple or quadruple at both ends of a glass tube having a uniform phosphor layer on the inner surface. A pair of filaments (electrodes) coated with an electron-emitting material (hereinafter referred to as an emitter) made of a ternary oxide is disposed, and an appropriate amount of Hg (mercury) and discharge are placed in a glass tube containing the filaments. It has a structure in which an inert gas such as Ar (argon) for facilitating the start is sealed for several Torr.

  When the hot cathode fluorescent lamp having such a structure is lit, a pair of filaments are energized to preheat the filaments and an alternating voltage of a predetermined voltage is applied between both filaments (electrodes). Then, the thermoelectrons emitted from the emitter of the filament of the electrode on the cathode side are accelerated by being pulled by the high potential of the filament of the electrode on the opposite anode side, and are accelerated into a rare gas such as Ar enclosed in the glass tube. It collides and ionizes this, and the generated electrons ionize the next Ar atom, leading to discharge.

  Then, as the temperature in the glass tube gradually rises as time passes and the vapor pressure of Hg in the glass tube increases to a predetermined pressure, the main flow of discharge shifts to mercury. Then, the Hg atoms with which the electrons collide emit ultraviolet rays (peak wavelength: λp = 253.7 nm), and the ultraviolet rays excite the phosphor located on the inner surface of the glass tube to convert the wavelength of the visible light from the phosphor layer. Is released. In this case, light (visible light) having various desired color tones can be obtained by using one or a plurality of types of phosphors appropriately selected.

  By the way, a thermionic emission type discharge lamp such as a hot cathode fluorescent lamp maintains a discharge while an emitter (electron radioactive substance) applied to the filament of the electrode emits an electron. Discharge does not occur when there is no more emission.

  One mechanism for eliminating the emission of electrons from the emitter is as follows. During stable discharge, a cathode bright spot is formed at the emitter of the cathode where emission of thermoelectrons is concentrated at one point. At this time, the temperature of the cathode luminescent spot is higher than the other parts due to current concentration, so the emitter of the luminescent spot part is lost mainly due to evaporation of the emitter, and the bright spot moves to the part where the adjacent emitter remains. To do. In this manner, the emitters are sequentially consumed, and the cathode bright spot moves from the low potential side to the high potential side of the filament coated with the emitter when the electrode is a cathode as the discharge time elapses. When all the emitters are consumed, the emission of electrons stops.

  However, there are not many life modes that reach the discharge life because all the emitters are consumed. Since the cathode bright spot is sputtered by Ar ions and Hg ions, the tungsten of the filaments evaporates. In particular, when the temperature of the bright spot is low, the amount of sputtering increases. Further, when the lamp voltage at the time of starting is high, the amount of spatter is large and portions other than the bright spot are also sputtered. These sputtered tungsten or the like adheres to the surface of the emitter and covers the emitter, so that the emission of electrons from the emitter is hindered, the bright spot is prevented from moving, and the emitter is already consumed and tungsten is exposed. Since the discharge current concentrates on the part and the temperature rises, the evaporation of tungsten is accelerated. In addition, since the time taken to start stable discharge after starting increases, sputtering at the time of starting is accelerated. As a result, the area where the emitter is covered and the thickness of impurities such as tungsten covering the emitter also increase, resulting in a significant loss of life. Such life modes are frequent.

  In addition, there is a life mode in which tungsten exposed by the cathode luminescent spot is consumed and tungsten exposed is gradually sputtered intensively by Ar ions and Hg ions, and finally the discharge life is reached by disconnection of that portion ( (See FIG. 7).

  As described above, the lifetime of a thermionic emission type discharge lamp is extremely caused by the behavior of the cathode bright spot with respect to the emitter at the time of discharge. Therefore, by controlling the behavior of the cathode bright spot at the time of discharge, the long lifetime of the lamp is controlled. Can be realized.

  As a method for controlling the cathode bright spot in a thermionic emission type discharge lamp, the cathode bright spot is utilized with the property that the filament moves from the low potential side to the high potential side when the electrode is a cathode as the discharge time elapses. A method has been proposed in which the polarity of the voltage applied to both ends of the filament is changed in order to energize the filament each time the power is turned on (see, for example, Patent Document 1).

Thus, every time the power is turned on, the position of the cathode bright spot in the filament is alternately moved to the low potential side of the filament to prevent the emitter from being consumed only from one direction. As a result, the above-mentioned life mode is avoided and the life of the lamp is extended.
Japanese Patent Laid-Open No. 6-111953

  However, the proposed method for extending the life of the lamp is effective when the continuous lighting time is relatively short. For example, the lamp is always lit, such as a guide light indicating the position of the evacuation exit and the direction of evacuation. When used as a light source for a lamp that needs to be maintained, the technique for extending the service life is not effective at all. Inherently, it cannot cope with applications that require the longest life.

  Therefore, the present invention was devised in view of the above problems, and its object is to suppress the consumption of the emitter by forcibly and continuously moving the position of the cathode bright spot on the emitter during discharge. This is to extend the life of the lamp.

  In order to solve the above-mentioned problem, the invention described in claim 1 of the present invention is such that a rare gas is sealed in at least a sealed space formed by a glass tube, and a coil-like shape is formed at both inner ends of the glass tube. In a hot cathode discharge lamp in which a filament formed by applying an electron radioactive substance to tungsten is disposed, a magnetic field generation source is disposed outside the hot cathode discharge lamp in the vicinity of the filament, and the discharge of the hot cathode discharge lamp is performed. A magnetic field component that moves at a predetermined speed from a direction perpendicular to the longitudinal direction of the filament is applied to the filament by repeatedly reciprocating the magnetic field generation source at a predetermined speed substantially parallel to the longitudinal direction of the filament. The cathode bright spot located on the filament is forcibly moved at a predetermined speed by the magnetic field. That.

  In the invention described in claim 2 of the present invention, a rare gas is sealed in at least a sealed space formed by a glass tube, and an electron radioactive substance is formed on coiled tungsten at both ends of the glass tube. In a hot cathode discharge lamp provided with a coated filament, a magnetic field generation source is provided outside the hot cathode discharge lamp in the vicinity of the filament, and the magnetic field generation source is discharged during the discharge of the hot cathode discharge lamp. Is rotated in a circular motion around the filament at a predetermined speed substantially parallel to a plane perpendicular to the longitudinal direction of the hot cathode discharge lamp, thereby causing the filament to move at a predetermined speed from a direction perpendicular to the longitudinal direction of the filament. A magnetic field component that moves in the direction is applied, and the cathode bright spot located on the filament is forced to move at a predetermined speed by the magnetic field. We are an butterfly.

  Further, in the invention described in claim 3 of the present invention, in any one of claims 1 and 2, the movement time of the magnetic field generation source is at most 60 seconds or less from the start of discharge of the hot cathode discharge lamp. It is characterized by being.

  Moreover, the invention described in claim 4 of the present invention is that in any one of claims 1 to 3, the magnetic field generation source has a motion velocity component substantially parallel to the filament of 0.5 to 0.5. It is 1.0 cm / sec.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the magnetic field generation source is a permanent magnet having a maximum magnetic energy product (BH) max of 10 to 40 MGOe. It is characterized by.

  According to a sixth aspect of the present invention, in any one of the first to fourth aspects, the magnetic field generation source is an electromagnet.

  The invention described in claim 7 of the present invention is the hot cathode discharge lamp according to any one of claims 1 to 6, wherein the phosphor is uniformly coated on the inner surface of the glass tube, and It is a hot cathode fluorescent lamp in which mercury is sealed in a sealed space.

  In the present invention, the cathode bright spot located on the filament is moved by the reciprocating motion along the filament or the rotational circular motion around the filament by the magnetism generation source arranged in the vicinity of the filament of the hot cathode discharge lamp. The magnetic field is forcibly moved at a predetermined speed.

  As a result, impurities such as tungsten deposited on the electron-emitting material are periodically removed by the cathode luminescent spots, the consumption of the electron-emitting materials by the cathode luminescent spots is suppressed, and an excessive current is supplied to the cathode luminescent spots. The disconnection of tungsten caused by concentration is suppressed.

  Therefore, it is possible to realize a long life of the hot cathode discharge lamp.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIG. 1 to FIG. 6 (the same parts are given the same reference numerals). The embodiments described below are preferable specific examples of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention particularly limits the present invention in the following description. Unless stated to the effect, the present invention is not limited to these embodiments.

  FIG. 1 is an explanatory diagram of a hot cathode fluorescent lamp. The hot cathode fluorescent lamp 1 is provided with a base 4 at both ends of a glass tube 3 having a phosphor 2 uniformly coated on its inner surface, and each base 4 has a pair of base pins 5 extending in the longitudinal direction of the outside of the glass tube 3. is doing.

  A pair of lead wires 7 supported by the stem 6 are disposed along the longitudinal direction of the glass tube 3 at both inner ends of the glass tube 3, and one end of each lead wire 7 is connected to each base pin 5. While being connected (not shown), the other end is connected to the filament 8 to support the filament 8.

  The inside of the glass tube 3 is made into a sealed space 9 by the caps 4 provided at both ends, and an appropriate amount of Hg (mercury) in the sealed space 9 and inert such as Ar (argon) for facilitating the start of discharge. Gas is sealed for several Torr (Hg, inert gas not shown).

  As shown in FIG. 2, the filament 8 is an electron-emitting material (hereinafter referred to as the emitter 11) made of a ternary oxide of (Ba / Sr / Ca) O on W (tungsten) 10 wound in a coil shape. Is applied. In the drawing, the filament 8 wound in a single manner is shown for the sake of explanation, but there are also cases where the filament 8 is wound in double, triple or quadruple.

  In the hot cathode fluorescent lamp having the above structure, as shown in FIG. 3, the present invention includes a magnetic field generation source 12 outside the fluorescent lamp 1 in the vicinity of the coiled filament 8 positioned at both ends of the fluorescent lamp 1. A magnetic field generation device 13 is arranged, and the magnetic field generation source 12 is configured to repeatedly reciprocate at a predetermined speed between two points that are substantially parallel to the filament 8 and have substantially the same distance to the center position of the filament. . At the same time, the moving distance of the magnetic field generation source 12 is set to be longer than the coil portion of the filament 8.

  Then, the magnetic field generated by the continuously moving magnetic field generating source 12 is applied to the filament 8 at an angle substantially perpendicular to the longitudinal direction of the filament 8, and the magnetic field maintaining this angle is at least between both ends of the coil portion of the filament 8. Are repeatedly reciprocated at a predetermined speed.

  In the present embodiment, a permanent magnet is employed as the magnetic field generation source 12, and the polarity of the magnet facing the filament 8 may be either the N pole or the S pole (in the figure, the case of the N pole is shown). .

  Next, a lighting control method for the hot cathode fluorescent lamp will be described. First, as shown in the explanatory diagram of FIG. 4, the filament 8 is energized by applying a predetermined filament voltage to each of the pair of cap pins 5 to preheat the filament 8, and between the cap pins 5 at both ends. A predetermined discharge voltage is applied to.

  Then, the thermoelectrons emitted from the filament 8 of the electrode on the cathode side are attracted and accelerated by the high potential of the filament 8 of the electrode on the opposite anode side, and the discharge continues as a discharge current. . At the same time, two points where the magnetic field generation source 12 of the magnetic field generation device 13 disposed near both ends of the hot cathode fluorescent lamp 1 are substantially parallel to the filament 8 and the distance to the central position of the filament 8 is substantially the same. A reciprocating motion is repeatedly performed between them at a predetermined speed.

  FIG. 5 shows the cathode bright spot on the filament when the magnetic field generation source is moved. The filament 8a on one end A side of the hot cathode fluorescent lamp is a cathode, and the filament 8b (not shown) on the other end B side is an anode, and the magnetic field generating source 12a is perpendicular to the longitudinal direction of the filament 8a. When the direction center line X is at the position M1 in the longitudinal direction of the filament 8a, the cathode bright spot Q is generated at the position P1 where the magnetic field generated by the magnetic field generating source 12a is the strongest in the filament 8a serving as the cathode. The emitter 11a of the filament 8a at the position P1 is evaporated and consumed by the cathode bright spot Q.

  After that, while the filament 8a on the end A side repeats alternating polarity of the anode and the cathode, the magnetic field generation source 12a moves at a predetermined speed, and the center line X of the magnetic field generation source 12a is at the position of M2. When moved, the position of the cathode bright spot Q moves from the position P1 of the filament 8a to the position P2 where the strength of the magnetic field is strongest in synchronization with the timing when the filament 8a becomes the cathode. The emitter 11a of the filament 8a at the position P2 is evaporated and consumed by the cathode bright spot Q.

  The magnetic field generation source 12a that has moved to the position of M2 continues to move at a predetermined speed without staying at the position of M2, and the magnetic field generation source while the filament 8a on the end A side repeats alternating polarity of the anode and cathode. When the center line X of 12a moves to the position of M3, the position of the cathode bright spot Q changes from the position of P2 of the filament 8a to the position P3 where the strength of the magnetic field is strongest in synchronization with the timing when the filament 8a becomes the cathode. Moving. The emitter 11a of the filament 8a at the position P3 is evaporated and consumed by the cathode bright spot Q.

  Then, since the cathode luminescent spot sequentially moves from the place consumed by the cathode luminescent spot of the emitter 11a to another place of the emitter 11a every predetermined time, further transpiration by the cathode luminescent spot Q at one point of the emitter 11a. Is prevented and consumption is avoided.

  Then, when the above operation is repeated and the cathode bright spot Q reaches one end Pb of the coil portion of the filament 8a, it is temporarily stopped there, and the magnetic field generating source 12a reverses its direction at the turning point Mb of the movement and reverses the opposite side. Movement of the magnetic field generation source 12a that moves in the direction of the turning point Ma and moves toward the point Ma from the time when the position of the strongest magnetic field of the magnetic field generation source 12a passes through the position of one end Pb of the coil portion of the filament 8a. Accordingly, the cathode bright spot Q starts to move toward the other end P1 of the coil portion of the filament 8a.

  As described above, the center X of the magnetic field generation source 12 repeatedly moves at a predetermined speed between the two turning points Ma and Mb, so that the cathode bright spot Q moves between the two ends P1 and Pb of the filament 8a. It moves repeatedly at a predetermined speed.

  Therefore, the cathode bright spot Q does not stay at one point on the emitter 11a of the filament 8a for a long time and the dwell time is almost the same, so that a specific place of the emitter 11a is not intensively evaporated. The emitter 11a is consumed uniformly.

  The above-described operation is the same in the relationship between the filament 8b on the other end B side of the hot cathode fluorescent lamp 1 (not shown) and the magnetic field generation source 12b. Therefore, the description of the operation on the other end B side of the hot cathode fluorescent lamp 1 is omitted here.

  For example, a permanent magnet is used as the magnetic field generation source. In that case, a permanent magnet of SmCo (samarium cobalt), NdFeB (neomagnetic iron boron), or AlNiCo (alnico) is suitable. The magnetic field generation source is not limited to a permanent magnet, and an electromagnet can also be used.

  As for the magnetic force of the magnet, it is desirable that the maximum magnetic energy product (BH) max is 10 to 40 MGOe. When the magnetic energy product is smaller than 10 MGOe, it is difficult to control the movement of the cathode bright spot. When the magnetic energy product is larger than 40 MGOe, the peripheral device using the magnetic material is affected by the magnetic field, which may impair the mountability.

  The moving speed of the magnetic field generation source is preferably 0.5 cm / sec to 1 cm / sec irrespective of the current density of the discharge current. When the moving speed is slower than 0.5 cm / sec, the consumption of the emitter due to the cathode bright spot increases, and when it is faster than 1 cm / sec, the temperature rise of the cathode bright spot is low (the temperature of the cathode bright spot is 800 ° C. to 1000 ° C. However, the efficiency of electron emission is not good. Further, the cathode bright spot cannot follow the movement of the magnetic field generation source (the movement of the magnetic field), making it difficult to control.

  The tube diameter of the hot cathode fluorescent lamp capable of controlling the movement of the cathode bright spot with the magnetic field generation source is desirably 40 mm or less as an experimental value. When the tube diameter is larger than 40 mm, the filament diameter becomes large, the response of the temperature rise of the filament at the position of the cathode bright spot is delayed, and the controllability of the cathode bright spot is deteriorated.

  The relationship between the length of the filament and the moving distance of the magnetic field generation source may be the same, or shorter than the length of the coil portion of the filament. However, considering the control efficiency, it is desirable that the coil length of the filament and the moving distance of the magnetic field generation source are substantially the same.

  In this embodiment, the magnetic field generation source is reciprocated along the filament. However, as shown in FIG. 6, the magnetic field generation source 12 is substantially parallel to the plane perpendicular to the longitudinal direction of the hot cathode fluorescent lamp 1. You may make it carry out the rotation circular motion of the circumference | surroundings at a predetermined speed. Which motion is selected may be determined in consideration of the installation conditions of the hot cathode fluorescent lamp, the motion mechanism of the magnetic field generation source, and the like.

  As described above, according to the present invention, the magnetic field generation device including the magnetic field generation source is disposed outside the fluorescent lamp in the vicinity of the filament located at both ends of the hot cathode fluorescent lamp, and the magnetic field generation source is the filament. It was made to move periodically in parallel with the longitudinal direction.

  As the magnetic field generating source moves, the cathode bright spot induced by the magnetic field of the magnetic field generating source periodically moves on the emitter of the filament at a predetermined speed, and the cathode bright spot concentrates on one point of the filament for a long time. I tried not to have it.

  As a result, impurities such as tungsten deposited on the electron-emitting material are periodically removed by the cathode luminescent spots, the consumption of the electron-emitting materials by the cathode luminescent spots is suppressed, and an excessive current is supplied to the cathode luminescent spots. The disconnection of tungsten caused by concentration is suppressed.

  Therefore, the lifetime of the hot cathode fluorescent lamp can be extended.

  If it is difficult to continue moving the magnetic field source during the discharge of the hot cathode fluorescent lamp, the magnetic field is applied only at the start of the discharge, at least when the emitter is consumed most, and the cathode bright spot is A method of greatly shifting the position of the bright spot is also effective for extending the life. In this case, the discharge start time is about 60 seconds after the tube current for discharge starts flowing.

It is explanatory drawing of a hot cathode fluorescent lamp. It is a front view of the filament of a hot cathode fluorescent lamp. It is explanatory drawing which shows embodiment of this invention. It is explanatory drawing which shows operation | movement of embodiment of this invention. It is explanatory drawing which shows the state of the filament in embodiment of this invention. It is explanatory drawing which shows other embodiment. It is explanatory drawing which shows the state of the conventional filament.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hot cathode fluorescent lamp 2 Phosphor 3 Glass tube 4 Cap 5 Cap pin 6 Stem 7 Lead wire 8 Filament 8a Filament 8b Filament 9 Sealed space 10 Tungsten 11 Emitter 11a Emitter 12 Magnetic field generator 13 Magnetic field generator

Claims (7)

  In a hot cathode discharge lamp in which a rare gas is enclosed in at least a sealed space formed by a glass tube and a filament made of a coiled tungsten coated with an electron radioactive substance is disposed at both ends of the glass tube. A magnetic field generation source is disposed outside the hot cathode discharge lamp in the vicinity of the filament, and the magnetic field generation source is repeated at a predetermined speed substantially parallel to the longitudinal direction of the filament during the discharge of the hot cathode discharge lamp. By reciprocating, a magnetic field component that moves at a predetermined speed from a direction perpendicular to the longitudinal direction of the filament is applied to the filament, and the cathode bright spot located on the filament is forced to a predetermined speed by the magnetic field. A method for controlling the lighting of a hot cathode discharge lamp, wherein   In a hot cathode discharge lamp in which a rare gas is enclosed in at least a sealed space formed by a glass tube and a filament made of a coiled tungsten coated with an electron radioactive substance is disposed at both ends of the glass tube. A magnetic field generation source is disposed outside the hot cathode discharge lamp in the vicinity of the filament, and the magnetic field generation source is substantially flush with a plane perpendicular to the longitudinal direction of the hot cathode discharge lamp during the discharge of the hot cathode discharge lamp. A magnetic field component that moves at a predetermined speed from a direction perpendicular to the longitudinal direction of the filament is applied to the filament by rotating circularly around the filament at a predetermined speed in parallel. A method for controlling the lighting of a hot cathode discharge lamp, characterized in that the cathode luminescent spot located at is forcibly moved at a predetermined speed.   3. The lighting control of the hot cathode discharge lamp according to claim 1, wherein the movement time of the magnetic field generation source is at most 60 seconds from the start of discharge of the hot cathode discharge lamp. Method.   The hot cathode according to any one of claims 1 to 3, wherein the magnetic field generation source has a motion velocity component substantially parallel to the filament with respect to the filament of 0.5 to 1.0 cm / sec. Discharge lamp lighting control method.   5. The lighting control method for a hot cathode discharge lamp according to claim 1, wherein the magnetic field generation source is a permanent magnet having a maximum magnetic energy product (BH) max of 10 to 40 MGOe.   The lighting control method for a hot cathode discharge lamp according to any one of claims 1 to 4, wherein the magnetic field generation source is an electromagnet.   7. The hot cathode fluorescent lamp according to claim 1, wherein the phosphor is uniformly coated on the inner surface of the glass tube and mercury is sealed in the sealed space. The lighting control method for a hot cathode discharge lamp according to any one of the preceding claims.

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