Emitter electrode having a strip shape

Abstract

A strip-shaped emitter electrode including at least one emission edge extending along the length of such emitter electrode. When the strip-shaped emitter electrode is coupled to a voltage supply, current or an electrical charge at the emission edge ionizes the air and generates corona discharge, resulting in ion production. Erosion occurs at the emission edge such that the lifespan of the strip emitter electrode is dependent, at least in part, on the width of the strip emitter electrode.

Description

BACKGROUND

Existing wire emitter electrodes (referred to as “Prior Art Wire Emitter(s)”) ionize the air and generate corona discharge at levels proportionate to the current running through the electrode. Such electrodes are operatively coupled to a voltage supply which enables such current flow. The amount of ionized particles and corona discharge generated is a function of the emitter current. The higher the emitter current, the more air is ionized and the greater the corona discharge.

Ozone production can be a byproduct of corona discharge if certain conditions are present. This ionization process can cause oxygen molecules (O₂) to split in the air. The split molecules seek stability and attach themselves to other oxygen molecules (O₂), forming ozone (O₃). Inhaling excess amounts of ozone can be undesirable and even harmful depending upon the conditions present in a given environment. Ozone generation for a given Prior Art Wire Emitter length at normal room humidity, temperature and pressure can be a function of the material of the wire, the emitter current and the diameter of the wire. For a given emitter current and material, the smaller the diameter of the wire, the less ozone is produced. One disadvantage to small diameter wires is that they tend to wear down at a relatively high rate.

Accordingly, there is a need to overcome or otherwise reduce the disadvantages described above.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A is a perspective view of a Prior Art Wire Emitter.

FIG. 1B is a perspective view of one embodiment of a strip emitter electrode, as described below.

FIG. 1C is an enlarged, perspective view of one embodiment of a strip emitter electrode, as described below.

FIG. 2 is a graph indicating ozone production of an air treatment apparatus using one embodiment of a strip emitter electrode compared to a Prior Art Wire Emitter electrode used to generate the same emitter current.

FIG. 3 is a front perspective view of one embodiment of an air treatment apparatus which includes the strip emitter electrode described below.

DETAILED DESCRIPTION

FIG. 1A illustrates a perspective view of a Prior Art Wire Emitter. The use of a strip emitter electrode 10, as illustrated in FIGS. 1B and 1C, overcomes or reduces the problems related to Prior Art Wire Emitters by exhibiting a longer structural lifetime and generating desired levels of corona discharge associated with acceptable amounts of ozone.

Referring now to FIGS. 1B and 1C, in one embodiment, the strip emitter electrode 10 includes a rectangular body having a length 12, a width 14, a thickness 16, and emission edges 18a and 18b. Edges 18a and 18b are defined by the length 12 and the thickness 16, and edges 18a and 18b extend along the length 12 of the strip emitter electrode 10. When a current flows through the strip emitter electrode 10, corona current concentrates on at least one of edges 18a and 18b. Accordingly, any erosion of the strip emitter electrode 10 caused by corona current progresses from the respective edge 18a or 18b of the strip emitter electrode 10 inward along the width 14. This enables strip emitter electrode 10 to perform the ionic emission function for a relatively long period of time. The concentration of corona at at least one of edges 18a and 18b of the strip emitter electrode 10 results in ionization similar to that resulting from corona emitted from a thin wire within corresponding levels of ozone generation.

With continued reference to FIG. 1C, erosion may progress inward from edge 18a. For example: after one period of operation, the edge 18a deteriorates and recedes to line 20a; after a longer period of operation, the edge 18a deteriorates and recedes to line 20b; and after an even longer period of time, the edge 18a deteriorates and recedes to line 20c. In on example, this process continues until the entire width 14 of the strip emitter electrode is depleted or disintegrated. The lifespan of the strip emitter electrode 10 is a function, in part, of the width 14 of the strip emitter electrode 10. All other variables being equal, in this example, the greater the width 14, the longer the lifespan of a strip emitter electrode 10. If edge 18a of the strip emitter electrode 10 were the only edge eroding due to current concentration, the life of the strip emitter electrode 10 would terminate approximately when the erosion reaches edge 18b. If both edges 18a and 18b are eroding due to current concentration, the life of the strip emitter electrode 10 would terminate approximately when the erosions lines extending inward from respective edges 18a and 18b converge.

Such a strip emitter electrode 10 may have any suitable rectangular geometry and have any suitable length 12, width 14 and thickness 16. For example, the width 14 of the strip emitter electrode 10 could extend from 0.1 mm upward. Additionally, the thickness 16 of the strip emitter electrode 10 could range from 0.01 mm to 0.15 mm. In one tested embodiment, the width 14 of the strip emitter electrode 10 is approximately 2.3 mm, and the thickness 16 of the strip emitter electrode 10 is approximately 0.02 mm. Additionally, the strip emitter electrode 10 may be composed of any suitable material. In one embodiment, the strip emitter electrode 10 is composed of molybdenum. In the illustrated and tested embodiment, the strip emitter electrode 10 has a flexible foil structure. It should be appreciated, however, that the strip emitter electrode 10 can have any suitable rigid or flexible structure, including, but not limited to: (a) a ribbon; (b) a foil; (c) a tape; (d) a belt or band; or (e) any other suitable relatively thin structure.

Referring now to Table 1 below, to demonstrate the relationship between Prior Art Wire Emitter diameter and ozone generation, consider a tungsten Prior Art Wire Emitter electrode between 0.1 and 0.12 mm in diameter. The following table illustrates the ozone production of such a Prior Art Wire Emitter electrode at a designated current as a function of the diameter of the wire.

TABLE 1
Wire Diameter, mm O3, mg/hr
0.12              2.62
0.1               2.23
0.08              1.96

As illustrated in Table 1, ozone generation resulting from such Prior Art Wire Emitter decreases with wire diameter. However, as described above, smaller diameter wires may not have a sufficient lifespan for practical application, breaking and requiring replacement because corona current erodes the Prior Art Wire Emitters.

In one test, ozone generation of an air treatment apparatus including Prior Art Wire Emitter electrodes was measured as a function of current at designated currents. Then, ozone generation of the same air treatment apparatus including a plurality of the strip emitter electrodes 10 was measured at the same current. Then, the two sets of results where compared, as illustrated in Table 2 below. For this test, Prior Art Wire Emitters having a diameter of 0.12 mm were used. Molybdenum strip emitter electrodes, having a width of 2.3 mm and a thickness of 0.02 mm, were used. In this particular test, both the Prior Art Wire Emitters and such strip emitter electrodes 10 were operated in an air treatment apparatus which also includes collector and driver electrodes. In this test, the emitter electrodes and the collector electrodes were operatively coupled to a voltage generator. Table 2 below and FIG. 2 include relevant test data.

TABLE 2
	O3, mg/hr	O3, mg/hr
	Strip Emitter	Prior Art Wire Emitter
I, μA	Electrodes	Electrodes
200	1.8	2.8
400	3.7	5.5
600	5.5	8

As illustrated in Table 2 and FIG. 2, operating at the same designated currents, the use of the strip emitter electrodes resulted in less ozone generation than the use of the Prior Art Wire Emitter electrodes.

Performance of the air treatment apparatus used in this test was also measured in terms of Clean Air Delivery Rate (“CADR”). CADR is the amount of clean air measured in cubic feet per minute that an air cleaner delivers to a room. The performance of the air treatment apparatus used in this particular test, independent of ozone generation differentiation, was substantially similar when using the strip emitter electrodes 10, as opposed to the Prior Art Wire Emitters. This is illustrated by the sample estimated CADR results of Table 3 below. The “High,” “Med,” “Low,” and “Quiet” designators in Table 3 refer to various operating modes of the air treatment apparatus from which these results were measured. While performing at similar CADR levels, the ozone generation using strip emitter electrodes 10 was significantly lower.

	TABLE 3
		CADR
		(Prior Art Wire Emitter	CADR
	Mode	Electrode)	(Strip Emitter Electrode)
	High	155.4	174.3
	Medium	137.6	138.6
	Low	124.3	135.2
	Quiet	100.6	110.3

It should be appreciated that although the strip emitter electrode 10 described in this application was tested in an air treatment apparatus including a collector electrode in the foregoing example, the strip emitter electrode 10 may be incorporated into a variety of air treatment devices including, without limitation, various electrode configurations, pure ionizers (such as a strip emitter electrode which causes ions to flow toward any suitable grounded object), or any other suitable device. For example, the strip emitter electrode could be utilized in air treatment devices including at least one of: (a) emitter electrodes; (b) collector electrodes; (c) electrodes interstitially located between the collector electrodes (driver electrodes); and (d) additional suitable electrodes. An example of such a device is shown in FIG. 3, which illustrates an air treatment apparatus including an elongated housing which supports the internal components of the air treatment apparatus. In this illustration, the air treatment apparatus could include an electrode assembly with at least one of the strip emitter electrodes 10 illustrated in FIGS. 1B and 1C. Though the housing shown has an elongated shape, it should be understood that other shapes for the air treatment apparatus are suitable. In one embodiment, such air treatment apparatus includes a control panel for turning on and off the air treatment apparatus, or for changing operating settings (e.g., low, medium, high or quiet). In operation, the air treatment apparatus draws surrounding air into the apparatus through the front air inlet. The front air inlet can include a plurality of fins, slats or louvers that facilitate air flow into the apparatus. An electrode assembly in the air treatment apparatus cleans or removes particles from the air as air flows through the apparatus.

The apparatus can remove dust particles and other airborne particles from the air, including particles which cause odor, as well as particles present in smoke and other gases. Also, the apparatus can condition and treat the air by removing or altering chemicals present in the air. Furthermore, the apparatus can collect and kill airborne pathogens and micro-organisms through the effect of the electric field produced by the electrode assembly and cold plasma of corona discharge. Once cleaned or otherwise treated, the air exits the apparatus through the rear air outlet. Similar to the front air inlet, the rear air outlet can include a plurality of fins, slats or louvers that facilitate air flow out of the apparatus.

In one embodiment, the strip emitter electrode 10 includes a first end and a second end, the first and second end both held by a tensioning mechanism or holder which holds the strip emitter electrode tight in a linear configuration, eliminating or reducing slack.

In various embodiments, the strip emitter electrode may be either a permanent or replaceable component of an air treatment apparatus or any device. Alternatively, the strip emitter electrode may constitute a device in and of itself (i.e., a pure ionizer as described above), used with a voltage source. In such embodiment, the strip emitter electrode can be a replaceable item.

Additionally, the strip emitter electrode may be fabricated in a variety of ways and by a variety of devices. For example, the strip emitter electrode could be produced as a product of: (a) a laser cutting method; (b) mechanical cutting method; (c) any combination of these methods; or (d) any suitable fabrication method like, for example, rolling. Such methods could employ a variety of cutting devices, including: (i) lasers; (ii) mechanical cutters; (iii) any combination of these devices; or (iv) any suitable device.

It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.

Claims

1. An electro-kinetic airflow producing device comprising: a strip-type emitter electrode and plural collector electrodes operatively and respectively coupled to a voltage source to generate a corona discharge and thereby produce the airflow,the strip-type emitter electrode having a length, a width, a thickness, and at least one emission edge which extends along the length of the emitter electrode, wherein the thickness of the emitter electrode is less than about 0.15 mm and wherein the emission edge thereof is subject to erosion based on the corona discharge during operation of the electro-kinetic airflow producing device, the erosion progressing in the width dimension of the emitter electrode, the width substantially exceeding the thickness and thereby extending the operative lifetime of the emitter electrode as compared with a wire-type emitter electrode design having substantially identical width and thickness.

2. The electro-kinetic airflow producing device of claim 1, wherein the strip-type emitter electrode has a flexible characteristic, a first end, and a second end, the first end and the second being configured to be held in place by at least one holder.

3. The electro-kinetic airflow producing device of claim 1, wherein the strip-type emitter electrode is fabricated using a cutting or rolling device selected from the group consisting of: (a) a laser; (b) a mechanical cutter; (c) any combination of a laser and a mechanical cutter; and (d) a roller.

4. The electro-kinetic airflow producing device of claim 1, configured as an ionic air treatment apparatus.

5. The electro-kinetic airflow producing device of claim 1, configured as an electro-kinetic air transporter-conditioner.

6. The electro-kinetic airflow producing device of claim 1, wherein the strip-type emitter electrode has a structure selected from the group consisting of: a ribbon; a foil; a tape; a belt; and a band.

7. The electro-kinetic airflow producing device of claim 6, wherein the strip-type emitter electrode is flexible along its length.

8. The electro-kinetic airflow producing device of claim 1, further comprising: an additional electrode positioned generally between a respective pair of the collector electrodes and downstream of the strip-type emitter electrode, the additional electrode operatively coupled to the voltage source as a driver electrode.

9. The electro-kinetic airflow producing device of claim 8, wherein the driver electrode is insulated.

10. The electro-kinetic airflow producing device of claim 1, further comprising: at least one additional strip-type emitter electrode coupled to the voltage source to generate a corona discharge and thereby contribute to the produced airflow.

11. An electro-kinetic airflow producing device comprising: a voltage supply;two or more collector electrodes; andat least one strip-type emitter electrode, the strip-type emitter electrode and collector electrodes coupled to the voltage supply and positioned to generate a corona discharge proximate an emission edge of the strip-type emitter electrode and thereby contribute to the produced airflow, the emission edge of the strip-type emitter electrode exhibiting a generally downstream facing cross-sectional thickness of less than about 0.15 mm and tolerating erosion of the emission edge in a generally upstream-oriented width dimension of the strip-type emitter electrode, a ratio of erosion-tolerating width to cross-sectional thickness being at least 10:1.

12. The electro-kinetic airflow producing device of claim 11, wherein the thickness is greater than about 0.01 mm.

13. The electro-kinetic airflow producing device of claim 12, wherein the thickness is approximately 0.02 mm.

14. The electro-kinetic airflow producing device of claim 11, wherein the strip-type emitter electrode is composed of molybdenum.

15. The electro-kinetic airflow producing device of claim 11, wherein the tolerated erosion of material in the width dimension of the strip-type emitter electrode exceeds the thickness thereof.

16. A method of extending an operational lifetime of an emitter electrode in an electro-kinetic airflow producing device, while generating a desirable level of corona discharge and limiting ozone production, the method comprising: providing a strip-type emitter electrode that exhibits a length, a width and a thickness;sizing the thickness of the strip-type emitter electrode in accord with emitter electrode material and operative emitter currents to generate a desired level of corona discharge with no more than an acceptable level of ozone production;sizing the width of the strip-type emitter electrode to tolerate erosion of material thereof throughout a desired operative lifetime of the emitter electrode, wherein the desired operative lifetime exceeds that during which operation of the electro-kinetic airflow producing device would be expected to erode, in the width dimension, an amount of material of the emitter electrode that exceeds the thickness thereof.

17. The method of claim 16, providing plural collector electrodes positioned generally downstream of the strip-type emitter electrode.

18. The method of claim 16, wherein the strip-type emitter electrode is composed of Molybdenum.

19. The method of claim 16, based on the thickness sizing, providing the strip-type emitter electrode with a thickness in a range from 0.01 mm to 0.15 mm.

20. The method of claim 16, based on the width sizing, providing the strip-type emitter electrode with a width that exceeds at least 0.1 mm.

21. The method of claim 16, based on the thickness and width sizing, providing the strip-type emitter electrode with a ratio of width to thickness of at least 10:1.

22. The method of claim 16, providing one or more additional strip-type emitter electrodes.