JP5191765B2 - High frequency discharge lamp system - Google Patents

Description

  The present invention relates to a high-frequency discharge lamp system provided with an antenna for concentrating electromagnetic waves in a discharge tube.

  As an example of a high frequency discharge lamp, an electrodeless discharge lamp having no electrode in a discharge space is known. Since this type of electrodeless discharge lamp has no filaments or electrodes in the discharge space, the life of the electrodeless discharge lamp does not decrease due to the exhaustion of the filaments or electrodes, and the life can be extended compared to fluorescent lamps and incandescent bulbs. In addition, since the electrodeless discharge lamp has no electrode, there is no restriction on the substance that can be used as an electrode, and a substance with good light emitting performance can be arranged in the discharge space, which is more than that of a discharge lamp using an electrode. Efficiency can be increased.

  Conventionally, as a high-frequency discharge lamp, for example, an electromagnetic wave transmission coaxial waveguide having an inner conductor and an outer conductor, and a discharge tube connected to the distal end of the waveguide, the discharge tube is formed as a discharge space inside. A double-ended type consisting of a pair of sealed parts with a sealed elliptical spherical part and a pair of sealed parts that are sealed at both ends of the elliptical spherical part, and the conductive assembly is close to the inner conductor of the waveguide The proximal end side sealing portion is inserted and held in the distal end opening portion of the waveguide, the conductor assembly and the outer conductor distal end portion are constituted by the electromagnetic wave irradiation portion, and the high frequency electromagnetic wave transmitted through the waveguide is transmitted to the electromagnetic wave irradiation portion. Has been proposed that irradiates the discharge space into the discharge space (see Patent Document 1).

  According to this high-frequency discharge lamp, the electromagnetic wave transmitted through the coaxial waveguide is irradiated into the discharge space through the conductor assembly without being illuminated through the quartz glass surface. Therefore, the luminous efficiency of the discharge tube can be increased accordingly.

Japanese Unexamined Patent Publication No. 2007-220531 (see pages 6 to 7, see FIG. 1)

  In the prior art, a configuration in which a part of the sealing part in the discharge tube is held in the electromagnetic wave irradiation part is adopted, but since the length of the embedded part in which the conductor assembly is embedded is not considered, When the length of the recessed portion is not sufficient, the electromagnetic wave is reflected and the light emission efficiency is lowered. For example, when an electric field is generated starting from the end face (feeding point) of the electromagnetic wave irradiation part, there are few wrap regions where the conductor assembly and the internal conductor overlap, and the length of the wrap region is λ (wavelength of electromagnetic waves) / 8. Otherwise, electromagnetic waves are reflected and it is difficult to form an electric field in the discharge space.

  The present invention has been made in view of the problems of the prior art, and an object thereof is to provide a high-frequency discharge lamp system capable of efficiently irradiating an electromagnetic wave into a discharge tube without reflecting the electromagnetic wave. It is in.

In order to achieve the object, in the high frequency discharge lamp system according to claim 1,
Introduced by the electromagnetic wave irradiation unit, an electromagnetic wave transmission unit that transmits electromagnetic waves generated from the power supply unit, an electromagnetic wave transmission unit that transmits electromagnetic waves generated from the power supply unit, an electromagnetic wave irradiation unit that introduces and radiates electromagnetic waves transmitted from the electromagnetic wave transmission unit A discharge tube that discharges and emits light by plasma generated by receiving an electromagnetic wave, and the electromagnetic wave irradiation unit includes an inner conductor that introduces the electromagnetic wave and a cylindrical outer conductor that covers the inner conductor, and the discharge tube Is a high-frequency discharge lamp system composed of a double-ended discharge tube having a sealed portion with a conductor assembly sealed inside at both ends ,
The length of the holding area where one of the sealing portions of the discharge tube is held by the electromagnetic wave irradiation portion of the L1, from the electromagnetic wave irradiation unit, out of the tip of the conductor assembly of the other sealing portion of the discharge tube, When the length to the tip of the conductor assembly farther from the electromagnetic wave irradiation part is L2, ε is the dielectric constant of the discharge tube, and λ is the wavelength of the electromagnetic wave, the inner conductor exists in the holding region. On the condition that it extends to a position covering the entire length of the sealing portion,
A configuration satisfying the relationship of L1> λ / (8ε ^1/2 ) and L2 <λ / (4ε ^1/2 ) was adopted .

(Operation) When the electromagnetic wave generated in the power supply part is transmitted to the electromagnetic wave irradiation part through the electromagnetic wave transmission part and irradiated to the discharge tube from the electromagnetic wave irradiation part, the irradiated electromagnetic wave causes high density in the discharge space of the discharge tube. Plasma is generated, and the luminescent material in the discharge space is evaporated and excited to emit light. In this case, the length of the holding area where one of the sealing portions of the discharge tube is held by the electromagnetic wave irradiation portion of the L1, the electromagnetic wave irradiation unit, out of the tip of the conductor assembly of the other sealing portion of the discharge tube, When the length to the conductor assembly tip farther from the electromagnetic wave irradiation part is L2, ε is the dielectric constant of the discharge tube, and λ is the wavelength of the electromagnetic wave, the inner conductor is the total length of the sealing part existing in the holding region On the condition that it extends to a position covering the electromagnetic wave, the relationship of L1> λ / (8ε ^1/2 ) and L2 <λ / (4ε ^1/2 ) is satisfied. ) Is transmitted from the electromagnetic wave radiating unit to the inside of the discharge tube without being reflected by the electromagnetic wave irradiating unit when the electromagnetic wave radiating unit is transmitted. For this reason, the luminous efficiency of the discharge tube can be improved.
In addition, when a double-ended discharge tube is used, the conductor assembly in the sealed portion protruding outside the electromagnetic wave irradiation portion of the sealed portion functions as an antenna. Rather, the arc can be formed in a stable state in the discharge tube.
In order to achieve the object, in the high-frequency discharge lamp system according to claim 2,
Introduced by the electromagnetic wave irradiation unit, an electromagnetic wave transmission unit that transmits electromagnetic waves generated from the power supply unit, an electromagnetic wave transmission unit that transmits electromagnetic waves generated from the power supply unit, an electromagnetic wave irradiation unit that introduces and radiates electromagnetic waves transmitted from the electromagnetic wave transmission unit A discharge tube that discharges and emits light by plasma generated by receiving an electromagnetic wave, and the electromagnetic wave irradiation unit includes an inner conductor that introduces the electromagnetic wave and a cylindrical outer conductor that covers the inner conductor, and the discharge tube Is a high-frequency discharge lamp system composed of a single-ended discharge tube having a sealed portion with a conductor assembly sealed inside at one end,
The length of the holding region where the sealing portion of the discharge tube is held in the electromagnetic wave irradiation unit is L1, the length from the electromagnetic wave irradiation unit to the tip of the discharge space in the discharge tube is L2, and ε is the discharge When the dielectric constant of the tube and λ is the wavelength of the electromagnetic wave, on the condition that the inner conductor extends to a position covering the entire length of the sealing portion existing in the holding region,
A configuration satisfying the relationship of L1> λ / (8ε ^1/2 ) and L2 <λ / (4ε ^1/2 ) was adopted .
(Operation) When the electromagnetic wave generated in the power supply part is transmitted to the electromagnetic wave irradiation part through the electromagnetic wave transmission part and irradiated to the discharge tube from the electromagnetic wave irradiation part, the irradiated electromagnetic wave causes high density in the discharge space of the discharge tube. Plasma is generated, and the luminescent material in the discharge space is evaporated and excited to emit light. At this time, the length of the holding region where the sealing portion of the discharge tube is held in the electromagnetic wave irradiation unit is L1, the length from the electromagnetic wave irradiation unit to the tip of the discharge space in the discharge tube is L2, and ε is the discharge tube When the dielectric constant is λ and the wavelength of the electromagnetic wave is λ, L1> λ / (8ε ^1/2 ), provided that the inner conductor extends to a position covering the entire length of the sealing portion existing in the holding region . Since the relationship of L2 <λ / (4ε ^1/2 ) is satisfied, the electromagnetic wave generated by the power supply unit (microwave) is transmitted through the electromagnetic wave transmission unit and then transmitted through the electromagnetic wave irradiation unit. Irradiation is concentrated in the discharge tube from the electromagnetic wave irradiation unit without being reflected. For this reason, the luminous efficiency of the discharge tube can be improved.
In addition, when a single-end type discharge tube is used, there is no conductor assembly that functions as an antenna, unlike the double-end type, so there is no heat loss at the antenna compared to when using a double-end type discharge tube. Therefore, the luminous efficiency of the discharge tube can be increased accordingly.

In the high-frequency discharge lamp system according to claim 3 , in the high-frequency discharge lamp system according to claim 1 or 2 , the sealing portion exposes the entire conductor assembly without exposing the conductor assembly to the outside. A sealed structure was obtained.

  (Operation) By making the sealing portion a sealing structure in which the entire conductor assembly is sealed inside without exposing the conductor assembly to the outside, there is no need to adopt a foil seal structure in the sealing portion. The assembly can be sealed with glass, leakage to the outside of the sealing portion can be prevented, and durability can be improved. In addition, there is no heat outflow from the conductor assembly to the inner conductor of the electromagnetic wave irradiation section, and the light emission efficiency of the discharge tube can be improved as the heat loss is reduced.

The high frequency discharge lamp system according to any one of claims 1 to 3 is configured such that L1> 8 mm and L2 <15.5 mm.

As is clear from the above description, according to claim 1, the luminous efficiency of the discharge tube can be improved , and further, the arc is stabilized in the discharge tube by using a double-ended discharge tube. It can be formed in a state.
According to the second aspect, the luminous efficiency of the discharge tube can be improved. Furthermore, by using a single-ended discharge tube, there is no heat loss in the antenna, and the luminous efficiency of the discharge tube is increased accordingly. Can be increased.

According to the third aspect , leakage to the outside of the sealing portion can be prevented, durability can be improved, and luminous efficiency of the discharge tube can be improved as heat loss is reduced.

According to claim 4, a specific high-frequency discharge lamp system can be provided.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 is a cross-sectional view of a high-frequency discharge lamp system showing an embodiment of the present invention, FIG. 2 is a cross-sectional view of a main part of the high-frequency discharge lamp system in Experiment 1, and FIG. 4 is a cross-sectional view of the main part of the high-frequency discharge lamp system in Experiment 2, FIG. 5 is a characteristic diagram showing the experimental results of Experiment 2, and FIGS. 6 (a), 6 (b), and 6 (c) are in Experiment 3. FIG. 7 is a characteristic diagram showing an experimental result of Experiment 3, FIG. 8 is a sectional view of an essential part of the high frequency discharge lamp system in a verification experiment, and FIG. 9 is an experimental result of the verification experiment. FIG. 10 is a cross-sectional view of a main part for explaining the relationship between the discharge tube and the electromagnetic wave irradiation unit when the size is optimized, and FIG. 11A is a double-end type sealing unit. FIG. 11B is a cross-sectional view of a discharge tube equipped with a single-end type sealing portion. It is a cross-sectional view of the conductive tube.

  In FIG. 1, a high frequency discharge lamp system 10 introduces and irradiates a power supply unit 12 that generates electromagnetic waves, an electromagnetic wave transmission unit 14 that transmits electromagnetic waves generated from the power supply unit 12, and an electromagnetic wave transmitted from the electromagnetic wave transmission unit 14. An electromagnetic wave irradiation unit 18 and a discharge tube 22 that discharges and emits light using plasma generated by receiving the electromagnetic wave introduced by the electromagnetic wave irradiation unit 18 are provided.

  The power supply unit 12 includes an oscillating unit 13 that generates an electromagnetic wave in a microwave band (300 MHz to 100 GHz) by electric power supplied from an in-vehicle battery. The oscillating unit 13 is, for example, a magnetron, a semiconductor switching element (FET or bipolar transistor). Etc.). At this time, the oscillating unit 13 oscillates at a frequency where the wavelength λ of the electromagnetic wave is 50 to 350 mm in a vacuum, for example, 2.45 GHz.

  The electromagnetic wave transmission unit 14 is formed of a metal circular pipe-shaped inner conductor 15, a metal circular pipe-shaped outer conductor 16 surrounding the inner conductor 15, and a circular pipe, and the inner conductor 15, the outer conductor 16, A dielectric member 17 made of quartz glass, which is an insulating member, is coaxially integrated. The inner conductor 15 and an outer conductor surrounding the inner conductor 15 are configured as, for example, a coaxial tube or a coaxial cable. Electromagnetic waves are transmitted between 16.

  The electromagnetic wave irradiation unit 18 is formed of a metal circular pipe-shaped inner conductor 19, a substantially hollow cylindrical shape, and a metal outer conductor 20 surrounding the inner conductor 19, and a circular pipe-shaped inner conductor 19. A heat insulating member interposed between the outer conductor 20, for example, a quartz glass spacer 21 is coaxially integrated, and serves as a launcher for introducing electromagnetic waves into the discharge tube 22. The longitudinal end is connected to the longitudinal end of the discharge tube 22.

  An annular flange 19 a is formed on one end in the longitudinal direction of the internal conductor 19, and this flange 19 a is press-fitted on the inner peripheral side of the internal conductor 15 of the electromagnetic wave transmission unit 14. That is, the inner conductor 15 and the inner conductor 19 are electrically connected via the flange 19a. Further, an annular step portion 20a is formed on one end side of the outer conductor 20 in the longitudinal direction, and an annular flange 20b is formed on the other end side in the longitudinal direction. One end side in the longitudinal direction of the outer conductor 16 is press-fitted. That is, the outer conductor 16 and the outer conductor 20 are electrically connected through the step portion 20a. Further, one end in the longitudinal direction of the spacer 21 is coupled to one end in the longitudinal direction of the dielectric 17 of the electromagnetic wave transmission unit 14, and the other end in the longitudinal direction of the spacer 21 is supported by the flange 20 b of the external conductor 20.

The discharge tube 22 is sealed (pinch seal) 24 by sealing (pinch seal) both ends of a glass (anhydrous quartz glass) tube having an elliptical spherical bulge 23 formed in the middle in the longitudinal direction. 25, the conductor assemblies 26 and 27 are sealed, and the inside of the elliptical spherical bulging portion 23 is configured as a discharge space 28. In the discharge space 28 of the discharge tube 22, a starting rare gas (1 to 20 atmospheres at room temperature) is enclosed together with a luminescent substance (NaI, ScI ₃ or the like).

  The conductor assembly 26 sealed (fixed) to the proximal end side sealing portion 24 of the sealing portions 24, 25 has a tungsten conductor rod 26a, a molybdenum foil 26b, and a molybdenum conductor rod 26c connected in a straight line. It is integrated. The molybdenum conductor rod 26c is press-fitted into the inner conductor 19 with the distal end of the proximal-side sealing portion 24 therebetween, and is not electrically connected to the inner conductor 19. A part of the tungsten conductor rod 26a protrudes into the discharge space 28 by a predetermined length.

  On the other hand, the conductor assembly 27 sealed (fixed) to the distal end side sealing portion 25 is integrated by connecting a tungsten conductor rod 27a, a molybdenum foil 27b, and a molybdenum conductor rod 27c in a straight line. A part of the tungsten conductor rod 27 a protrudes into the discharge space 28 by a predetermined length, and the molybdenum foil 27 b and the molybdenum conductor rod 27 c are sealed in the front end side sealing portion 25.

  The tungsten conductor rods 26a and 27a and the molybdenum conductor rods 26c and 27c constituting the conductor assemblies 26 and 27 are made of, for example, a potassium-doped tungsten wire or a tri-doped tungsten wire having an outer diameter of 0.25 mm, and 26b and 27b are The molybdenum conductor rods 26c and 27c are composed of molybdenum wires having an outer diameter larger than that of the tungsten conductor rods 26a and 27a.

  At this time, since the conductor assemblies 26 and 27 are not electrically connected to the inner conductor 19, it is not necessary to employ a foil seal structure for the sealing portions 24 and 25, and the sealing portions 24 and 25 are sealed with glass. It is also possible to eliminate the heat outflow from the conductor assembly 26 to the internal conductor 19 and the heat outflow from the conductor assembly 27 to the outside, thereby improving the luminous efficiency of the discharge tube 22.

  When the molybdenum conductor rod 26 c of the proximal end side sealing portion 24 of the discharge tube 22 is press-fitted inside the inner conductor 19 of the electromagnetic wave irradiation portion 18, the sealing portion 24 is gripped (clamped) by the inner conductor 19. As a result, the tip end portion of the molybdenum conductor rod 26c and the end portion in the longitudinal direction of the internal conductor 19 are arranged close to each other.

  In this state, when an electromagnetic wave is generated from the power supply unit 12, the electromagnetic wave transmitted from the power supply unit 12 to the electromagnetic wave transmission unit 14 passes through the conductor assembly 26 sealed to the proximal end side sealing unit 24 and the conductor assembly 26. The discharge space 28 is irradiated by the surrounding outer conductor 20. At this time, the irradiated electromagnetic wave (high-frequency electric field generated in the electromagnetic wave irradiation unit 18) generates high-density plasma in the discharge space 28, and the luminescent substance in the discharge space 28 is evaporated and excited to emit light. .

  In this case, since the tungsten conductor rod 26a of the conductor assembly 26 constituting the electromagnetic wave irradiation unit 18 protrudes into the discharge space 28, the electromagnetic wave transmitted by the electromagnetic wave transmission unit 14 is reliably transmitted through the tungsten conductor rod 26a. Into the discharge space 28.

  Further, the conductor assembly 27 sealed to the front end side sealing portion 25 of the discharge tube 22 also acts as an antenna in the same manner as the conductor assembly 26, and a high electric field concentrates around the conductor assembly 27, so that an arc is formed in the conductor assembly. It converges toward 27 and the arc (shape) is stabilized. In particular, when used as a light source for automotive lamps such as headlamps, the discharge tube 22 is used in a horizontal lighting form, but since the arc (shape) is stable, the arc does not come into contact with the tube wall so as to have an optimum shape. The shape of the discharge tube 22 (tube wall) can be designed, leading to an improvement in luminous efficiency.

  Here, in order to verify that electromagnetic waves (microwaves) generated from the power supply unit 12 are transmitted through the electromagnetic wave transmission unit 14 and then are concentratedly irradiated in the discharge space 28 without being reflected by the electromagnetic wave irradiation unit 18. In addition, Experiments 1 to 4 were performed as experiments for obtaining luminous efficiency when the discharge tube 22 was turned on.

  In each experiment, an arc tube containing mercury was used as a model of the discharge tube 22.

  First, in Experiment 1, as shown in FIG. 2, it is assumed that the portions corresponding to the lengths of both ends in the longitudinal direction of the arc tube (discharge tube 22) function as receiving antennas, and the longitudinal direction of the arc tube (discharge tube 22). The length of both ends in the direction was set to the length of both ends of the antenna = L, and the length of both ends of the antenna L was changed within a range of several tens of mm (25 mm to 32 mm) to obtain the luminous efficiency when the arc tube was turned on. The experimental result of Experiment 1 is shown in FIG.

  In FIG. 3, the vertical axis represents the luminous efficiency [lm / W], and the horizontal axis represents the length L at both ends of the antenna. Graph g61 shows the characteristics when the input power to the arc tube is 60 W, graph g51 shows the characteristics when the input power to the arc tube is 50 W, and graph g41 shows the input power to the arc tube. The characteristic when the power is 40 W is shown.

  From FIG. 3, it can be seen that the luminous efficiency can be maximized by setting the length L at both ends of the antenna to L = 31 mm when the input power to the arc tube is 40 W to 60 W. This is considered that the electric field applied to the inside of the arc tube becomes the strongest when the length L at both ends of the antenna is set to L = 31 mm, and becomes weaker as the length L at both ends of the antenna becomes shorter than L = 31 mm.

  In Experiment 2, as shown in FIG. 4, the length L of both ends of the antenna is fixed to L = 31 mm, and the insertion amount L1 (in the electromagnetic wave irradiation unit 18 in the sealing unit 24 of the arc tube (discharge tube 22)). The length in the longitudinal direction of the holding region inserted and held by the electromagnetic wave irradiation unit 18 was changed within a range of several mm to several tens of mm (4 mm to 12 mm) to obtain the luminous efficiency when the arc tube was turned on. . The experimental result of Experiment 2 is shown in FIG.

  In FIG. 5, the vertical axis indicates the luminous efficiency [lm / W], and the horizontal axis indicates the arc tube insertion amount L1. The graph g62 shows the characteristics when the input power to the arc tube is 60 W, the graph g52 shows the characteristics when the input power to the arc tube is 50 W, and the graph g42 shows the input power to the arc tube. Shows the characteristics when the output is 40 W.

  From FIG. 5, when the input power to the arc tube is 50 W and 60 W, the longer the insertion amount L1, the higher the luminous efficiency. However, when the input power to the arc tube is 40 W, the emission efficiency increases when the insertion amount L1 increases. It turns out that it falls a little. When the input power to the arc tube is 50 W and 60 W, it is considered that the electric field applied to the arc tube is stronger as the insertion amount L1 is longer.

  In Experiment 3, in order to investigate whether or not the luminous efficiency changes when the position L of the discharge space 28 of the arc tube (discharge tube 22) is changed with the length L of both ends of the antenna being constant, three types are examined. The luminous efficiency when the arc tube was turned on was determined. The experimental result of Experiment 3 is shown in FIG.

  First, in the first experiment, as shown in FIG. 6A, the arc tube (discharge tube 22) is such that the center of the antenna end length L of the arc tube (discharge tube 22) is the center of the discharge space 28. ) Is fixed to the electromagnetic wave irradiation unit 18 with the insertion amount L1 = 4.0 mm, and the input power to the arc tube is 40 W, 50 W, and 60 W. The characteristic of the luminous efficiency at this time is shown by a graph a1 in FIG.

  In the second experiment, as shown in FIG. 6B, from the center of the antenna both ends length L of the arc tube (discharge tube 22), 5.4 mm closer to the tip becomes the center of the discharge space 28. The arc tube was fixed to the electromagnetic wave irradiation unit 18 with an insertion amount L1 = 4.0 mm, and the input power to the arc tube was 40 W, 50 W, and 60 W. The characteristic of luminous efficiency at this time is shown by a graph b1 in FIG.

  In the third experiment, as shown in FIG. 6C, the center of the discharge space 28 is closer to the 5.4 mm electromagnetic wave irradiation unit 18 from the center of the antenna end length L of the arc tube (discharge tube 22). As described above, the arc tube was fixed to the electromagnetic wave irradiation unit 18 with the insertion amount L1 = 4.0 mm, and the input power to the arc tube was set to 40 W, 50 W, and 60 W. The characteristic of luminous efficiency at this time is shown by a graph c1 in FIG.

  From the experimental results of Experiment 3, the luminous efficiency of the arc tube (discharge tube 22) indicates that the center of the discharge space 28 is 5.4 mm from the center of the antenna end length L of the arc tube (discharge tube 22). It turns out that it is the highest when it is close, but there is no significant difference in either case. This is considered that even if the position of the discharge space 28 of the arc tube (discharge tube 22) is changed, there is no great difference in the strength of the electric field applied in the arc tube.

  From each experiment result of Experiment 1 to Experiment 3, the arc tube (discharge tube 22) is brought closer to the electromagnetic wave irradiation part (launcher) 18 and the insertion amount L1 into the inner conductor 19 of the arc tube (discharge tube 22) is longer. It was presumed that the luminous efficiency of the arc tube (discharge tube 22) was improved, and the following verification experiment (additional experiment) was conducted.

  In the verification experiment (experiment 4), as shown in FIG. 8, the amount of protrusion of the arc tube (discharge tube 22) from the electromagnetic wave irradiation part (launcher) 18 (= the discharge tube 22 tip side from the longitudinal end surface of the electromagnetic wave irradiation part 18) The length of the discharge region exposed to the outside and contributing to the discharge in the longitudinal direction (L2) is fixed at 16 mm, and the insertion length (antenna insertion length) L1 together with the antenna end length L is fixed. Was changed in the range of several mm to obtain the luminous efficiency. The result of this verification experiment is shown in FIG.

  In FIG. 9, the vertical axis represents the luminous efficiency [lm / W], and the horizontal axis represents the insertion amount (antenna insertion length) L1 of the arc tube (discharge tube 22). Graph g63 shows the characteristics when the input power to the arc tube is 60 W, graph g53 shows the characteristics when the input power to the arc tube is 50 W, and graph g43 shows the input power to the arc tube. Shows the characteristics when the output is 40 W.

  From FIG. 9, the luminous efficiency of the arc tube (discharge tube 22) increases as the insertion amount (antenna insertion length) L1 of the arc tube (discharge tube 22) becomes longer at input powers 40W to 60W. I understand. This is considered to be because a stronger electric field is applied to the arc tube (discharge tube 22) as the insertion amount (antenna insertion length) L1 of the arc tube (discharge tube 22) becomes longer.

  Considering the results of the above experiments, the results are as follows.

  (1) When the influence of the radiation resistance on the antenna end length L was investigated, the luminous efficiency of the arc tube (discharge tube 22) increased near the antenna end length L = 31 mm, but the effect was not significant. I understood.

  (2) Experiments 2 and 3 were performed based on the assumption that the entire antenna end length L was an antenna. In Experiments 2 and 3, the luminous efficiency of the arc tube (discharge tube 22) changed. It is considered that the estimation that the entire antenna end length L is an antenna was not accurate.

  (3) In Experiments 2 and 3, the closer the arc tube (discharge tube 22) is to the electromagnetic wave irradiation part (launcher) 18, the higher the luminous efficiency of the arc tube (discharge tube 22) is that of the electromagnetic wave irradiation of the antenna. The cause is considered to be that there is little energy loss (energy loss due to glass or the like covering the antenna) until the electromagnetic wave (microwave) supplied to the unit 18 reaches the arc tube (discharge tube 22).

  (4) In the verification experiment (Experiment 4), the longer the insertion amount (antenna insertion length) L1 of the arc tube (discharge tube 22), the higher the luminous efficiency of the arc tube (discharge tube 22). If the length of the insertion part of the electromagnetic wave irradiation unit 18 on the power supply side is short, the electromagnetic wave (microwave) reflected at the end of the insertion part of the electromagnetic wave irradiation unit 18 interferes with the incident wave. Conceivable.

Next, in order to verify the above (4), when the insertion amount (antenna insertion length) L1 of the arc tube (discharge tube 22) is further made longer than 15 mm, the arc tube (discharge tube 22) is filled. As a simulation for investigating how the intensity of the electric field changes, an electric field intensity distribution analysis was performed using an electromagnetic field simulator.
In this simulation, the high-density plasma shows electrical characteristics similar to a metal that is very easy to carry current with almost all atoms ionized, and energy is converted into light and consumed in the plasma. In consideration of the occurrence of energy loss, the discharge part in the discharge space 28 of the arc tube (discharge tube 22) is made of a substance having high conductivity and internal resistance, and other parts are made of a complete conductor. It was.

  In this simulation, the amount of insertion (antenna insertion length) L1 of the arc tube (discharge tube 22) is made constant, and the length from the end surface of the electromagnetic wave irradiation unit (launcher) 18 to the tip is changed to make the arc tube It was investigated how the intensity of the electric field applied in the (discharge tube 22) changes.

  When an electric field intensity distribution analysis was performed using an electromagnetic field simulator, the insertion amount (antenna insertion length) L1 of the arc tube (discharge tube 22) was fixed, and the electromagnetic wave irradiation part (launcher) 18 from the end surface to the tip It was found that when the length of the tube was around 15 mm, the electric field was most strongly applied to the arc tube (discharge tube 22).

  Similarly to the insertion amount (antenna insertion length) L1 of the arc tube (discharge tube 22), if the length from the end surface of the electromagnetic wave irradiation unit (launcher) 18 to the tip is shorter than 15 mm, the electromagnetic wave irradiation unit It is considered that the electromagnetic wave (microwave) reflected at the tip of 18 interferes with the incident wave.

Therefore, considering the heat capacity of the arc tube (discharge tube 22), the insertion amount (antenna insertion length) L1 of the arc tube (discharge tube 22) should be as short as possible, and from the end face of the electromagnetic wave irradiation part (launcher) 18 The optimum length (distance) to the tip is considered to be about λ / (4ε ^1/2 ) = 15.5 mm.

  From the simulation results, as shown in FIG. 10, the following size is optimal for the arc tube (discharge tube 22).

Antenna end length L = 31 mm = λ / (2ε ^1/2 )
Length of the holding region inserted into the electromagnetic wave irradiation unit 18 in the sealing unit 24 = insertion amount of the arc tube (discharge tube 22) (antenna insertion length) L1 = 15.5 mm = λ / (4ε ^{1 / 2} ) ,
The length of the discharge region L2 = 15.5 mm = λ / (4ε ^1/2 ) indicating the distance from the longitudinal end surface of the electromagnetic wave irradiation unit 18 to the tip of the discharge tube 22.

  Here, λ represents the wavelength of the electromagnetic wave (microwave), and ε represents the dielectric constant of quartz glass or ceramic constituting the arc tube (discharge tube 22).

On the other hand, considering that the arc tube (discharge tube 22) has a heat loss due to the conductor assemblies 26 and 27, the arc tube (discharge tube 22) has the sealing portion 24 held in the electromagnetic wave irradiation unit 18. The holding region is L1, the discharge region where the arc tube (discharge tube 22) is exposed from the electromagnetic wave irradiation unit 18 is L2, ε is the dielectric constant of the arc tube (discharge tube 22), and λ is the wavelength of the electromagnetic wave. If the inner conductor 19 extends to a position covering almost the entire length of the sealing portion 24 existing in the holding region,
It is necessary to satisfy the relationship of L1> λ / (8ε ^1/2 ) and L2 < λ / (4ε ^1/2 ) .

  At this time, considering that heat loss due to the conductor assemblies 26 and 27 is reduced, the arc tube (discharge tube 22) needs to satisfy the relationship of L1 ≧ (L2) / 2.

  Further, as the discharge tube 22, as shown in FIG. 11A, a double-ended discharge tube 22a in which the conductor assemblies 26 and 27 are constituted by a single tungsten conductor rod 26a and 27a can be used.

  Furthermore, as the discharge tube 22, as shown in FIG. 11 (b), a discharge space 30 is formed inside a bulging portion 29 formed using quartz glass or ceramic, and the longitudinal end of the bulging portion 29 is formed. Alternatively, a single-ended discharge tube 22b in which a sealing portion (pinch seal portion) 31 is formed adjacent to the discharge space 30 and a conductor assembly 32 is sealed in the sealing portion 31 can be used. .

  The conductor assembly 32 is composed of a single tungsten conductor rod 32a. One end side in the longitudinal direction of the conductor assembly 32 protrudes into the discharge space 30 and the other end side in the longitudinal direction is accommodated in the sealing portion 31 without being exposed to the outside.

As for discharge tube 22a, 22b, the sealing parts 24 and 31 are inserted in the internal conductor 19 of the electromagnetic wave irradiation part 18, respectively. The length of the holding region where the conductor assemblies 26 and 32 overlap the inner conductor 19 in the longitudinal direction of the sealing portions 24 and 31 is defined as L1 as the insertion amount (antenna insertion length) of the discharge tube 22a. The length from the longitudinal end face of the electromagnetic wave irradiation unit 18 to the tip of the conductor assembly 27 or the tip of the discharge space 30 is set to L2 as a length corresponding to the discharge region, and ε is set to the discharge tube 22a, When the dielectric constant is 22b and λ is the wavelength of the electromagnetic wave, on the condition that the inner conductor 19 extends to a position covering almost the entire length of the sealing portions 24, 31.
The relations L1> λ / (8ε ^1/2 ) and L2 < λ / (4ε ^1/2 ) are satisfied.

  When the double end type discharge tube 22a is used, the conductor assembly 27 also functions as an antenna in the same manner as the conductor assembly 26. Therefore, the arc is more stable in the discharge tube 22 than when the single end type discharge tube 22b is used. It can be formed in a state.

  On the other hand, when the single-end type discharge tube 22b is used, since the conductor assembly 27 does not exist, the heat loss to the antenna is less than when the double-end type discharge tube 22a is used, and the light emission of the discharge tube 22b correspondingly. Efficiency can be increased.

According to the present embodiment, the length of the holding region where the sealing portion 24 is held in the electromagnetic wave irradiation unit 18 is L1, and the discharge region in which the arc tube (discharge tube 22) is exposed from the electromagnetic wave irradiation unit 18 to the outside. When the length is L2, ε is the dielectric constant of the arc tube (discharge tube 22), and λ is the wavelength of the electromagnetic wave, the inner conductor 19 extends to a position covering almost the entire length of the sealing portion 24 existing in the holding region. On the condition that the relationship of L1> λ / (8ε ^1/2 ) , L2 < λ / (4ε ^1/2 ) is satisfied, the electromagnetic waves are efficiently reflected without being reflected. Can be irradiated inside.

  Further, according to this embodiment, since the conductor assembly 26 of the discharge tube 22 and the internal conductor 19 of the electromagnetic wave irradiation unit 18 are not connected, it is not necessary to employ a foil seal structure for the discharge tube 22, and the conductor assembly 26. 27 can be sealed with glass, gas leakage to the outside at the sealing portions 24 and 25 can be prevented, and durability can be improved. In this case, there is no heat outflow from the conductor assembly 26 to the inner conductor 19 of the electromagnetic wave irradiation unit 18 and heat outflow from the conductor assembly 27 to the outside, so that the luminous efficiency of the discharge tube 22 is further increased as the heat loss is reduced. be able to.

Furthermore, according to the present embodiment, the length of the holding region inserted into the electromagnetic wave irradiation unit 18 in the sealing portion 24 where the conductor assembly 26 is sealed = the insertion amount of the discharge tube 22 (the antenna insertion length). ) L1 is made longer than λ / (8ε ^1/2 ) , and the length L2 of the discharge region indicating the distance from the longitudinal end surface of the electromagnetic wave irradiation unit 18 to the tip of the discharge tube 22 is λ / (4ε ^1/2 ). Therefore, the high-frequency electric field is concentrated on the discharge tube 22 and the light emission efficiency of the discharge tube 22 can be improved.

It is sectional drawing of the high frequency discharge lamp system which shows one Example of this invention. It is principal part sectional drawing of the high frequency discharge lamp system in Experiment 1. FIG. FIG. 6 is a characteristic diagram showing an experimental result of Experiment 1. It is principal part sectional drawing of the high frequency discharge lamp system in Experiment 2. FIG. FIG. 6 is a characteristic diagram showing an experimental result of Experiment 2. (A), (b), (c) is principal part sectional drawing of the high frequency discharge lamp system in Experiment 3. FIG. FIG. 10 is a characteristic diagram showing an experimental result of Experiment 3. It is principal part sectional drawing of the high frequency discharge lamp system in verification experiment. It is a characteristic view which shows the experimental result of verification experiment. It is principal part sectional drawing for demonstrating the relationship between both when the size of a discharge tube and an electromagnetic wave irradiation part is optimized. (A) is sectional drawing of the discharge tube provided with the double end type sealing part, (b) is sectional drawing of the discharge tube provided with the single end type sealing part.

DESCRIPTION OF SYMBOLS 10 High frequency discharge lamp system 12 Power supply part 14 Electromagnetic wave transmission part 15 Inner conductor 16 Outer conductor 18 Electromagnetic wave irradiation part 19 Inner conductor 20 Outer conductor 22,22a, 22b Discharge tube 24,25,31 Sealing part 26,27,32 Conductor assembly 28, 30 Discharge space

Claims (4)

Introduced by the electromagnetic wave irradiation unit, an electromagnetic wave transmission unit that transmits electromagnetic waves generated from the power supply unit, an electromagnetic wave transmission unit that transmits electromagnetic waves generated from the power supply unit, an electromagnetic wave irradiation unit that introduces and radiates electromagnetic waves transmitted from the electromagnetic wave transmission unit A discharge tube that discharges and emits light by plasma generated by receiving an electromagnetic wave, and the electromagnetic wave irradiation unit includes an inner conductor that introduces the electromagnetic wave and a cylindrical outer conductor that covers the inner conductor, and the discharge tube Is a high-frequency discharge lamp system composed of a double-ended discharge tube having a sealed portion with a conductor assembly sealed inside at both ends ,
The length of the holding area where one of the sealing portions of the discharge tube is held by the electromagnetic wave irradiation portion of the L1, from the electromagnetic wave irradiation unit, out of the tip of the conductor assembly of the other sealing portion of the discharge tube, When the length to the tip of the conductor assembly farther from the electromagnetic wave irradiation part is L2, ε is the dielectric constant of the discharge tube, and λ is the wavelength of the electromagnetic wave, the inner conductor exists in the holding region. On the condition that it extends to a position covering the entire length of the sealing portion,
A high frequency discharge lamp system characterized by satisfying a relationship of L1> λ / (8ε ^1/2 ) and L2 <λ / (4ε ^1/2 ) . Introduced by the electromagnetic wave irradiation unit, an electromagnetic wave transmission unit that transmits electromagnetic waves generated from the power supply unit, an electromagnetic wave transmission unit that transmits electromagnetic waves generated from the power supply unit, an electromagnetic wave irradiation unit that introduces and radiates electromagnetic waves transmitted from the electromagnetic wave transmission unit A discharge tube that discharges and emits light by plasma generated by receiving an electromagnetic wave, and the electromagnetic wave irradiation unit includes an inner conductor that introduces the electromagnetic wave and a cylindrical outer conductor that covers the inner conductor, and the discharge tube Is a high-frequency discharge lamp system composed of a single-ended discharge tube having a sealed portion with a conductor assembly sealed inside at one end,
The length of the holding region where the sealing portion of the discharge tube is held in the electromagnetic wave irradiation unit is L1, the length from the electromagnetic wave irradiation unit to the tip of the discharge space in the discharge tube is L2, and ε is the discharge When the dielectric constant of the tube and λ is the wavelength of the electromagnetic wave, on the condition that the inner conductor extends to a position covering the entire length of the sealing portion existing in the holding region,
L1> λ / (8ε ^1/2 ), L2 <λ / (4ε ^1/2 A high frequency discharge lamp system characterized by satisfying the following relationship: The high frequency discharge lamp system according to claim 1 or 2 , wherein the sealing portion has a sealing structure in which the conductor assembly is entirely sealed without exposing the conductor assembly to the outside. The high frequency discharge lamp system according to claim 1, wherein L1> 8 mm and L2 <15.5 mm.

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