CN1749638A

CN1749638A - Ion stable type cold cathode fluorescent lamp lighting system

Info

Publication number: CN1749638A
Application number: CNA200410077896XA
Authority: CN
Inventors: 邓明进
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-09-16
Filing date: 2004-09-16
Publication date: 2006-03-22

Abstract

The stable ion type cold cathode fluorescent lamp lighting system has one radial DC electric field formed inside cold cathode fluorescent lamp tube, so that free electrons inside the lamp tube may be accelerated to collide with gas atom frequently to produce enough energy to free the gas electrons, and the free Hg ions and Ar ions acted by the radial DC electric field have radial speed become zero while reaching the fluorescent coating to avoid collision to the fluorescent coating, the generation of non-crystal fluorescent layer and the embedding of Hg ion into the fluorescent coating. One axial reverse equivalent DC electric field is formed to avoid accumulation of Hg in the electrode to prolong the service life of the lamp tube and the fluorescent coating. In addition, the lamp tube has brightness further raised by the excessive energy the radial DC electric field provides.

Description

Ion stable type cold cathode fluorescent lamp lighting system

Technical field

The present invention relates to a kind of cold cathode fluorescent lamp lighting system, especially refer to that a kind of delegation that forms is to DC electric field in the cold cathode fluorescent lamp pipe, so that the ion that interior electrode of this fluorescent tube and gas ionization come out, because of this radially effect of DC electric field, when a phosphor body coating surface that evenly is coated with near this tube inner wall, the speed vanishing, present inactive state, and the axial anti-Equivalent DC electric field of mat, avoid mercury to accumulate on electrode, to prolong the life-span of fluorescent lamp.

Background technology

At present general fluorescent lamp lighting system, as shown in Figure 1, its glass lamp 10 mainly is in order to form a confined space, this space mainly is full of argon (argon, be called for short Ar) wait inert gas (its air pressure be about atmospheric pressure 0.3%) and Trace Mercury (mercury, abbreviation Hg), this tube inner wall is coated with particulate phosphor body coating 11 (Phosphor Layer), its material comprises the crystallization of manganese zinc silicate (Zinc Silicate, Zn ₂SiO ₄: Mn, about 2 microns of diameter), with luminescent substance as visible light; The two ends of this fluorescent tube 10 are respectively equipped with the filament 121,122 (double as negative electrode Cathode) that is made of tungsten filament, respectively an end of this filament 121,122 passes an insulation bolt 123 respectively and is connected to a starter 13 (starter), and its other end then passes an insulation bolt 123 respectively and is connected to an AC power 16 by a stabilizer (ballast) 14 and a switching switch 15 (Switch).As shown in Figure 2, this starter 13 is made of a small-sized neon light 130 and a capacitor C in parallel, be full of neon (neon in this small-sized neon light, be called for short Ne), and be provided with two electrodes 131,132, and 131,132 at this two electrode is open-circuit condition between stand-down, and wherein this electrode 132 is to be made by bimetal leaf, bending after being heated can contact another electrode 131 and reach the purpose of short circuit; This stabilizer 14 is inductors, is around in a soft magnetism iron core with insulated copper wire and forms, and is in order to cooperate this AC power 16 and stabilizer 14, to control the electric current I of this starter 13 ₁₃And the electric current of fluorescent tube 10, lost efficacy to avoid this starter 13 and fluorescent tube 10.

As shown in Figure 1, the start step of this illuminator is as follows:

(1) after this change-over switch 15 is switched on, the neon discharge heating that the electrode of this starter 13 is 131,132 makes the electrode 132 of this bimetal leaf be heated and bending at once, and connects with another electrode 131, forms short-circuit condition, forces the electric current I of this starter ₁₃This filament 121,122 of flowing through makes its heating up and sends a large amount of thermoelectrons, but this moment because the control of this stabilizer 14, make the voltage at these fluorescent tube 10 two ends, be not enough to make current lead-through in this fluorescent tube IO and luminous.

(2) after a while, because of these two electrodes, 131,132 short circuits, neon therebetween, because of losing voltage, and stop discharge and heating, cause the electrode 132 of this bimetal leaf to jump out of another electrode 131, the flow through electric current I of this starter 13, filament 121,122 and stabilizer 14 of instantaneous trip because of cooling ₁₃

(3) this stabilizer (inductor) 14 is because of electric current I ₁₃Suddenly disappear, be to cooperate the capacitor C of this starter 13 about 1500 volts voltage that vibrates, this voltage major part is absorbed by this stabilizer 14, about 600 volts across as shown in Figure 1 a, b point-to-point transmission, and keep this magnitude of voltage a period of time, this magnitude of voltage is not enough to trigger this starter 13, but is enough to force the thermoelectron in this fluorescent tube 10 to evoke photoelectric effect (photoelectriceffect), and then makes argon carry out chain gas discharge (gas discharge) and generation argon ion Ar ^{+ 2}And argon electronics e _a ^-, this argon electronics e _a ^-The energy that is had is enough to make mercury to carry out chain gas discharge, and produces a large amount of mercury ion Hg ^{+ 2}And mercury electronics e _h ^-, respectively this particle (particle) flies to scurry separately, runs foul of each other to give birth to go out, and causes the plasma (plasma) that forms a dynamic equilibrium (equilibrium) in this fluorescent tube 10 eventually, wherein mercury electronics e _h ^-Carry wavelength 2537 dusts (A, promptly 10 ^-10M) mercury ultraviolet light (ultrayiolet light) energy, and argon electronics e _a ^-Then carry the ultraviolet luminous energy of its characteristic.

When aforementioned various particles are flown to this phosphor body coating 11 of these fluorescent tube 10 inwalls of collision, will respectively wherein phosphor body be produced different effects.Argon electronics e wherein _a ^-Can't make this phosphor body luminous, the mercury electronics e of wavelength 2537 dusts _h ^-Then, carry out photoelectric effect with this phosphor body according to Stokes Law and following quantum theory formula:

ΔW = \frac{hc}{λ} \cdot \cdot \cdot \cdot \cdot \cdot \cdot \cdot \cdot \cdot \cdot \cdot (1)

And make phosphor body send the visible light of 380～780 dusts, reach illumination purposes.In formula (1), the excitation energy that on behalf of electronics, Δ W discharge; H represents the plank constant, is 6.62517*10 ^-34Joule. second; C represents the light velocity, is 3*10 ⁸Meter per second; λ represents wavelength, and unit is a rice.Because, illuminator shown in Figure 1 is that the thermoelectron of mat hot cathode (hot cathode) activates light-emitting procedure, have another name called " hot cathode fluorescent lamp lighting system " (hot cathode fluorescent lighting system is called for short HCFL) so plant traditional illuminator.

This phosphor body coating 11 is the crystal type structure, and each atom is positioned in the lattice, after being subjected to external radiation (as the ultraviolet light of above-mentioned wavelength 2537 dusts) and exciting, sends visible light.Therefore, if this crystal structure is constant, then this function will exist.Only if after being subjected to the mercury ion and argon ion bump (bombardment) of kinetic energy, atom in the lattice lattice of very easily overflowing, and cause these phosphor body coating 11 surfaces to produce amorphous fluorescent layer (amorphous layer), this amorphous fluorescent layer not only loses the function of sending visible light, can absorb external radiant energy on the contrary, so this amorphous layer (amorphous layer) thickness calculates according to following formula:

S = C \sqrt{tI} \cdot \cdot \cdot \cdot \cdot \cdot \cdot \cdot \cdot (2)

Wherein I represents electrical current, and t represents conduction time, and on behalf of this phosphor body, C resist these bumps and unshift stable coefficient, and S represents amorphous layer thickness.When this amorphous layer thickness increases gradually, these phosphor body coating 11 brightness will reduce gradually.Mercury ion will in the bump after, imbed in the fluorescent layer, and this imbed the action be non-reversible reaction.So the decrystallized and mercury atom of aforementioned fluorescent layer is imbedded phenomenon, will cause the luminosity B of this phosphor body coating 11, successively decrease according to following formula:

\frac{B_{t}}{B_{0}} = \exp (- α \sqrt{tI}) \cdot \cdot \cdot \cdot \cdot \cdot \cdot \cdot \cdot (3)

B wherein _tRepresent the brightness of time point t, B _oRepresent original brightness, α represents the light absorption constant of amorphous layer.Because in aforementioned formula, α and C are definite value, I is roughly constant during switching on, so can be merged into a coefficient, obtains following Lehmann formula:

\frac{B_{t}}{B_{0}} = \exp (- \sqrt{t / v}) \cdot \cdot \cdot \cdot \cdot \cdot \cdot \cdot \cdot (4)

ν=1/ (C ²α ²I) this formula is to be proposed in J.Electrochem Soc. periodical February nineteen eighty-three by Willi Lehlmann, and through Osamu Tadaetal. in June, 1984 confirm in J.Electrochem Soc. periodical.Therefore, can conclude the brightness of this fluorescent lamp 10, will be because of the phenomenon of imbedding of the decrystallized and mercury atom of phosphor body, and increase in time, successively decrease gradually.

Because LCD (liquid crystal display, abbreviation LCD) invention, especially after LCD is widely used in hand-held computer, in order to fluorescent lamp lighting system as back lighting, be to arise at the historic moment, this kind fluorescent lamp lighting system also is referred to as " cold cathode fluorescent lamp lighting system (coldcathodes fluorescent lamp lighting system; be called for short CCFL) ", as shown in Figure 3, its structure and " hot cathode fluorescent lamp lighting system " shown in Figure 1 are compared, and following listed difference is arranged:

L, no filament;

2, no neon starter;

3, no stabilizer (inductor);

4, power supply is that power supply circuit by LCD itself provides, and its frequency rises to the high frequency of about 55K Hz.

Cold cathode fluorescent lamp pipe with the long 160mm of caliber 3mm is an example, shown in Figure 3, when its negative electrode 221,222 cross-over connections after about 55KHz voltage is about the AC power 26 of 1600V to frequency, mercury vapour in this fluorescent tube 20 promptly carries out the luminescence process of similar hot-cathode fluorescent light tube shown in Figure 1, this kind fluorescent lamp is owing to being not luminous by hot filament, so be referred to as " cold cathode fluorescent lamp pipe ".

In Fig. 1 and two kinds of illuminators shown in Figure 3, optimal power supply is that first involves half-wave symmetry down, and promptly crest factor (crest factor is called for short C.F.) is zero waveform.Generally be supplied to the 60Hz sine-wave power of " hot-cathode fluorescent light tube " shown in Figure 1, even conform with ideal; But be supplied to the 55KHz power supply of " cold cathode fluorescent lamp pipe " shown in Figure 3, then because of being produced by electronic circuit (as: Royer inverter), so distribute according to its part characteristic, and the resistance of the interior plasma of fluorescent tube, can't satisfy the null requirement of crest factor, so having an axial Equivalent DC electric field all the time is present in the plasma, if if the equivalent potential of negative electrode 221 is higher than the equivalent potential of another negative electrode 222, force ion gradually to another negative electrode 222 migrations (migration), and deposit and form alloy on negative electrode 222, this phenomenon.Meaning in order to excite the mercury composition of ultraviolet light, to reduce gradually, the brightness of this cold cathode fluorescent lamp pipe 20 also will be successively decreased thereupon, so mercury deposition, promptly becomes decision two main causes in its illumination life-span in the alloying of negative electrode and the problem that aforementioned phosphor body is decrystallized and mercury is imbedded.According to this two decisive factor, the industrial standard of existing cold cathode fluorescent lamp tube lifetime, the life-span of cold cathode fluorescent lamp pipe is required to be brightness 50% in 20,000 hours at least.

In addition, the electromagnetic field that AC power 26 is produced not only disturbs contiguous electric equipment.Also may damage near the healthy of user, so the labor group of Sweden has stipulated a safety standard in 1991, and through legislation for the TCO91 rules, its normative content is as shown in the table, in the hope of ensureing user's health of human body and safety:

	?TCO91
	?TCO91	Electrostatic pressure Electrostatic Potential	＜± 500 volts
Electromagnetic field (Magnetic field) frequency band I 5Hz～2kHz frequency band II 2kHz～400kHz	? ?→200nT _rms, 30 centimeters reach 50 centimeters position measurement → 25nT on every side in display the place ahead _rms, 50 centimeters position measurements approximately on every side in display the place ahead	Electrostatic pressure Electrostatic Potential	＜± 500 volts
		AC field (Alternating Electric Field) frequency band I 5Hz～2kHz frequency band II 2kHz～400kHz	? ? ?→10V/m _rms, about 30 centimeters position measurement → 1.0V/m in display the place ahead _rms, about 30 centimeters and 50 centimeters position measurements on every side in display the place ahead

The flasher that is produced as for AC power 26, the injury that user's eyes are caused, as: easily cause the user to suffer from diseases such as myopia,, still do not have safety standard at present, use restraint though medical science confirms.

Because many shortcomings of aforementioned cold cathode fluorescent lamp lighting system, the present invention designs a cold cathode fluorescent lamp lighting system simple in structure and with low cost, with effective solution foregoing problems, significantly increase its service life, and reduce it health of human body and the safe influence that is caused.

Summary of the invention

Purpose of the present invention, provide a kind of ion stable type cold cathode fluorescent lamp lighting system, this system forms a DC electric field radially in a cold cathode fluorescent lamp pipe, remove and make the electronics that dissociates out in the fluorescent tube, increase outside the ability of plasma formation, and make plasma interior mercury ion and argon ion, because of this radially effect of DC electric field, when the phosphor body coating surface that evenly is coated with near this tube inner wall.Its radial velocity vanishing, in plasma, present radially static state, to prevent its impact fluorescence body atom, avoid this phosphor body coating surface to produce the amorphous fluorescent layer, or this mercury ion embeds in the phosphor body, effectively prolong the service life of this phosphor body coating, and the brightness that makes this fluorescent tube is because of this additional energy of providing of direct current place radially, and obtains further to improve.

Another object of the present invention, it is configuration one direct current power supply outside this cold cathode fluorescent lamp pipe, to set up an axial anti-Equivalent DC electric field in fluorescent tube, to prevent that the mercury ion in the plasma from moving to the lower electrode of equivalent potential, effectively avoid mercury deposition on this electrode, to form alloy, guarantee the unlikely consume of mercury composition in this fluorescent tube, to prolong the service life of this cold cathode fluorescent lamp pipe.

Description of drawings

Below in conjunction with accompanying drawing the specific embodiment of the present invention is described in further detail.

Fig. 1 is a traditional hot cathodouminescence lamp illuminating system schematic diagram.

Fig. 2 is the employed stabilizer schematic diagram of traditional hot cathodouminescence lamp illuminating system.

Fig. 3 is traditional cold cathode fluorescent lamp lighting system schematic diagram.

A kind of ion stable type cold cathode fluorescent lamp lighting system schematic diagram that Fig. 4 is provided for a preferred embodiment of the present invention.

Fig. 5 is the schematic diagram of another preferred embodiment of the present invention.

Symbol description

Fluorescent tube ... 30,40

Phosphor body coating ... 311,411

Electrode ... 321,322

Conductive coating ... 312,412

Insulation bolt ... 323,42

Central electrode ... 36,46

Main power source ... 381

DC electric field power supply radially ... 382

Axial anti-equivalent electric field ionization source ... 383

Main dc power supply ... 48

The specific embodiment

A preferred embodiment of the present invention, as shown in Figure 4, provide a kind of ion stable type cold cathode fluorescent lamp lighting system, this system comprises a fluorescent tube 30, one main power source 381 (can be direct current or AC power), one radially DC electric field power supply 382 and an axial anti-equivalent electric field ionization source 383 assemblies such as (supposing that an electrode 321 equivalent potentials are higher than another electrode 322), wherein these fluorescent tube 30 inwalls are coated with conductive coating a 312 (as: IndiumTin Oxide earlier, be called for short ITO, or Antimony Tin Oxide, be called for short ATO), be coated with a phosphor body coating 311 on this conductive coating 312 again, making this conductive coating 312 just be positioned at 311 of these fluorescent tube 30 inwalls and this phosphor body coating, this conductive coating 312 and mat one lead pass an insulation bolt 323 and are connected to the radially positive pole of DC electric field power supply 382 of outer set this of this fluorescent tube 30; Dispose a central electrode 36 in this fluorescent tube 30 in addition, an end of this central electrode 36 then be mat one lead pass one the insulation bolt 323 be external to this radially negative pole of DC electric field power supply 382; This main power source 381 is two electrodes 321,322 that are connected across this cold cathode fluorescent lamp pipe 30 via this axial anti-equivalent electric field ionization source 383 (being dc source), and at 321,322 formation of this two electrode, one axial Equivalent DC electric field (being axial electric field), make electronics quicken, starting produces the photoelectricity chain reaction with the argon and the mercury of these fluorescent tube 30 interior gases, form plasma, make the phosphor body coating 311 of these fluorescent tube 30 inwalls send visible light, reach illumination purposes.When the voltage of this main power source 381 forms plasma in this fluorescent tube 30 after, promptly can drop to the voltage of keeping of about 400V by about 1600V, to carry out normal illumination work.

In this preferred embodiment, this axial anti-equivalent electric field ionization source 383 will be at this two electrode 321,322 form an axial anti-Equivalent DC electric field, its polarity is the polarity that cooperates the axial Equivalent DC electric field that this main power source 381 set up, make this axial anti-Equivalent DC electric field just can offset axial Equivalent DC electric field in this fluorescent tube 30, so, can prevent effectively that the mercury ion in the plasma from moving to the lower electrode of equivalent potential, avoid mercury deposition on this electrode, to form alloy, so can guarantee the unlikely consume of mercury composition in this fluorescent tube, further prolong the service life of this cold cathode fluorescent lamp pipe 30.

In addition, in this cold cathode fluorescent lamp pipe 30, when the band mercury ion of energy and argon ion clashed into this phosphor body coating 311, the energy that is had was mechanical kinetic energy, the atom of impact fluorescence body, the Yi Lingqi displacement causes the surface of this phosphor body coating 311 to produce the amorphous fluorescent layer, makes it can send the afunction of visible light originally, even make mercury atom embed in the phosphor body because of bump, the luminosity that causes this phosphor body coating 311 increases in time, successively decreases gradually.Therefore, in this preferred embodiment, the present invention is with this voltage strength of being provided of DC electric field power supply 382 radially, be designed to and form a DC electric field radially 312 of this central electrode 36 and this conductive coatings, this radially DC electric field just can make mercury ion in the motion and argon ion the time near these phosphor body coating 311 surfaces, the radial velocity vanishing, promptly be radially inactive state, to prevent its impact fluorescence body atom, avoid these phosphor body coating 311 surfaces to produce the amorphous fluorescent layer, and the generation mercury atom embeds the situation in the phosphor body, significantly to prolong the life-span of this phosphor body coating 311, and make the brightness of this fluorescent tube 30, because of this radially DC electric field power supply 382 provide electronics extra energy, and obtain further to improve.

In another preferred embodiment of the present invention, omitted assemblies such as radially DC electric field power supply 382 set in embodiment illustrated in fig. 4 and axial anti-equivalent electric field ionization source 383, and the structure more to simplify.Design this cold cathode fluorescent lamp lighting system, as shown in Figure 5, this illuminator only comprises assemblies such as a fluorescent tube 40 (these fluorescent tube 40 full argon and Trace Mercury) and a main dc power supply 48, wherein these fluorescent tube 40 inwalls are coated with a conductive coating 412 earlier, be coated with a phosphor body coating 411 on this conductive coating 412 again, make this conductive coating 412 just be positioned at 411 of these fluorescent tube 40 inwalls and this phosphor body coating, this conductive coating 412 and mat one lead pass an insulation bolt 42 and are connected to the positive pole that is located at this outer main dc power supply 48 of this fluorescent tube 40.What this need pay special attention to be, dispose a central electrode 46 in this fluorescent tube 40 in addition, the one end passes the negative pole that an insulation bolt 42 is external to this main dc power supply 48, when this main dc power supply 48 when this central electrode 46 and this conductive coating 412 apply voltage, to form a DC electric field radially betwixt, make electronics quicken, starting produces the photoelectricity chain reaction with the ar atmo and the mercury atom of these fluorescent tube 40 interior gases, form plasma, make the phosphor body coating 411 of these fluorescent tube 40 inwalls send visible light, reach illumination purposes.The voltage of this main dc power supply 48 forms plasma in this fluorescent tube 40 after, promptly drop to the voltage of keeping of about 400V, carry out normal illumination work by about 1600V.

In another preferred embodiment as shown in Figure 5, mat activates the photoelectric effect of these fluorescent tube 40 interior argons and mercury and sets up plasma, since this radially the DC electric field value cooperate with the suitable of plasma density, just can make mercury ion and argon ion in the plasma, near these phosphor body coating 411 surfaces the time, the radial velocity vanishing, promptly be radially inactive state, to prevent its impact fluorescence body atom, avoid these phosphor body coating 411 surfaces to produce the amorphous fluorescent layer, or the generation mercury atom embeds the facts in the phosphor body, so not only can significantly prolong the life-span of this phosphor body coating 411, the brightness of this fluorescent tube 40 is also given the extra energy of electronics because of this main dc power supply 48 provides, and obtains further to improve.

In addition, owing to be to use dc source in preferred embodiment as shown in Figure 5, the electric current that this main dc power supply 48 and this fluorescent tube are 40 is direct current, except that not disturbing the person and the instrument passage of scintillation light that also unlikely generation damages user's eyes.

The above only is the best specific embodiment of the present invention, and only structural feature of the present invention is not limited thereto, and anyly is familiar with this skill person in field of the present invention, can think easily and variation or modification, all can be encompassed in the claim of following this case.

Claims

1, a kind of ion stable type cold cathode fluorescent lamp lighting system, it is characterized in that: this system forms a DC electric field radially in a cold cathode fluorescent lamp pipe, to make the positive charged ions in the plasma in this fluorescent tube, because of this radially effect of DC electric field, and when a phosphor body coating surface that evenly is coated with near this tube inner wall, its radial velocity vanishing presents radially inactive state.

According to the described ion stable type cold cathode fluorescent lamp lighting system of claim 1, it is characterized in that 2, this system comprises:

One conductive coating, it is coated on this tube inner wall, between between this tube inner wall and this phosphor body coating;

One central electrode, it is configured in the central position in this fluorescent tube;

One main dc power supply, be located at outside this fluorescent tube, its positive pole is connected to this conductive coating, its negative pole is connected to this central electrode, to form radially DC electric field between this conductive coating and this central electrode, the ion that makes electrode and gas ionization come out, because of this radially effect of DC electric field, near the phosphor body coating surface time, the radial velocity vanishing presents radially inactive state.

3, according to the described ion stable type cold cathode fluorescent lamp lighting system of claim 1, it is characterized in that: in this cold cathode fluorescent lamp pipe, set up an axial anti-Equivalent DC electric field.

According to the described ion stable type cold cathode fluorescent lamp lighting system of claim 3, it is characterized in that 4, this system comprises:

Two electrodes are located at the two ends of this cold cathode fluorescent lamp pipe respectively;

One main power source is in order to supply direct current or alternating current;

One axial anti-equivalent electric field ionization source, it is connected with this main power source, and be connected across on this two electrode, between this two electrode, to form this axial anti-Equivalent DC electric field, its polarity is the polarity that cooperates the axial Equivalent DC electric field that this main power source sets up, and makes this axial anti-Equivalent DC electric field just can offset the interior axial Equivalent DC electric field of this fluorescent tube.

5, according to the described ion stable type cold cathode fluorescent lamp lighting system of claim 4, it is characterized in that: this axial anti-equivalent electric field ionization source is a direct current power supply.

According to the described ion stable type cold cathode fluorescent lamp lighting system of claim 5, it is characterized in that 6, this system comprises:

One DC electric field power supply radially, be located at outside this fluorescent tube, its positive pole is connected to this conductive coating, its negative pole is connected to this central electrode, to form radially DC electric field between this conductive coating and this central electrode, the ion that makes electrode and gas ionization come out, because of this radially effect of DC electric field, near this phosphor body coating surface the time, the radial velocity vanishing presents radially inactive state.

7, a kind of ion stable type cold cathode fluorescent lamp lighting system is characterized in that: this system sets up an axial anti-Equivalent DC electric field in a cold cathode fluorescent lamp pipe.

According to the described ion stable type cold cathode fluorescent lamp lighting system of claim 7, it is characterized in that 8, this system comprises:

One axial anti-equivalent electric field ionization source, it is connected with this main power source, and be connected across on this two electrode, between this two electrode, to form axial anti-Equivalent DC electric field, its polarity is the polarity that cooperates the axial Equivalent DC electric field that this main power source sets up, and makes this axial anti-Equivalent DC electric field just can offset this interior axial Equivalent DC electric field of this fluorescent tube.

According to the described ion stable type cold cathode fluorescent lamp lighting system of claim 8, it is characterized in that 9, this axial anti-equivalent electric field ionization source is a direct current power supply.