Method for non-contact cleaning of fiber optic connectors and endfaces

Abstract

A cleaning device (100) for cleaning a fiber end face, comprising a dispensing nozzle (104) configured to expel a jet column (118) generated by the Coanda effect by intermittently injecting a cleaning solvent into the jet column (118). The method comprises impinging the jet column (118) onto the fiber end face (120) while maintaining a certain stand-off distance from the end face to be cleaned.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to provisional patent application No. 63 / 170,821, filed on April 5, 2021, in the name of Emily J. Peck et al., entitled “DEVICE AND METHOD FOR NON-CONTACT CLEANING OF FIBER OPTICCONNECTORS AND END FACES”. Background Technology 1. Technical Field

[0004] This invention generally relates to a method for cleaning the ferrule end surface of an optical fiber using a non-contact cleaning device. The ferrule end surface can be effectively cleaned, whether it is exposed or mounted in a ferrule connector (such as a plug or partition) for interconnection with another optical fiber or optoelectronic device.

[0005] In fiber optic networks, fiber optic strands (typically with a diameter of approximately 8 micrometers) are formed into cables by wrapping the strands in a protective sheath (not shown) and then connecting the ends of two cables by butt joint. For this purpose, the ends of individual fiber optic strands 10a, 10b, and 10c ( Figure 1A , Figure 1B and Figure 1C The fiber strands are typically stripped from the sheath and bonded and encapsulated in the center of rod-shaped ceramic ferrules 12a, 12b, and 12c. These ferrules provide an increased surface area for fine polishing of the exposed end faces of the fiber strands. The ferrule end faces 14a, 14b, and 14c are polished to a flat surface. Figure 1A Slightly convex ( Figure 1B ), or at an angle of approximately 8° ( Figure 1C These sleeves are then fitted into various types of connector housings, such as connector 16, to reduce reflected light when connected to another fiber. Figure 2 The connector is connected via a connector or partition 18 to a similar device (e.g., connector 16'). Figure 3 Precise interconnection is required to ensure accurate alignment of the mated fiber optic strands. For cleaning purposes, Figure 3 The component is disassembled to expose the end face of the sleeve for cleaning, while the component remains connected to its associated connector or the relevant half of the partition 18.

[0006] Figure 4The end of an optical fiber cable 19 is shown, comprising an optical fiber strand 20 with an outer protective sheath or sleeve 22, the end portion of which is stripped, and the stripped portion of the strand 20 is encapsulated in a collar 24 having an end face 24a. A lens 26 is fixed to the collar 24 at its end face 24a. The lens may be spherical or nearly spherical in construction to make the collar 24 an extended beam (“EB”) collar. The lens 26 is typically a collimating lens, although it may also be an imaging lens. In any case, the lens 26 is arranged to be optically transmitted to the end of the associated optical fiber strand 20.

[0007] Figure 5 A pair of fiber optic cables 19, 19' are shown, each cable having a corresponding EB clamp 24, 24', whose corresponding lenses 26, 26' are optically connected to each other via connectors 28, 28'. Connectors 28, 28' can be interconnected by any suitable means, such as mechanical fasteners or couplers. Connectors 28 and 28' are each configured to be isolated from each other, thereby allowing inspection and cleaning of the disconnected clamp end faces 24, 24a' and their associated lenses 26, 26'.

[0008] Figure 6 It shows Figure 5 One of the connectors, namely connector 28, is disconnected from the associated connector 28' and is therefore ready for cleaning.

[0009] For example, as mentioned above, the cleanliness of cable connections is a key factor in maintaining peak signal communication performance; however, such cable connections are highly susceptible to contamination at the adjacent end faces of optical fibers. Therefore, cleaning the end faces before the fiber ends are interconnected and / or after they have become contaminated during normal use is crucial.

[0010] 2. Existing Technology

[0011] It is known that conventional air brushes in the art, utilizing reciprocating conical needle valves, will produce the Coanda effect discussed below. The Coanda effect is well known to play a significant role in shaping the jet pattern of the air brush.

[0012] U.S. Patent 7,232,262, granted to S. Lytle (“Lytle”) et al. on June 19, 2007, discloses a cleaning apparatus for cleaning the end face of an optical fiber contained in an interface device. This apparatus utilizes a pressurized fluid (such as air or nitrogen) to deliver a solvent (such as a mixture of hydrocarbons and terpenes) by deploying the nozzle end of a pressurized fluid delivery tube within a solvent delivery tube with a diameter larger than the pressurized fluid delivery tube. Lytle's apparatus is inserted into connector 200. See, for example, Lytle's... Figure 2And columns 9, rows 41-50 and columns 9, rows 58 to 10, rows 3. In columns 11, rows 6-22, from the discharge port (i.e., nozzle end 114) to the fiber end face 202 ( Figure 2 The distance is preferably about 0.02 to 0.20 inches, for example, 0.05 inches; however, Lytle notes that "other distances are also applicable to the invention." Starting from row 15 of column 11, Lytle notes that if the nozzle tip is too close to the fiber end face, the increased back pressure reduces cleaning efficiency, while if the nozzle tip is too far from the fiber end face, the energy of the gas / solvent jet is dissipated, thus reducing cleaning efficiency.

[0013] U.S. Patent 6,821,025, granted to GJ Gerhard (“Gerhard”) on November 23, 2004, is in... Figure 2 A device is disclosed that includes a pressurized gas / cleaning solvent discharge port or nozzle 114, spaced apart from an optical fiber end face 202 in a manner similar to that described in Lytle. This configuration, contained within a cleaning assembly 100 (Figure 1 and column 5, row 23, etc. in Gerhard's), is designed to insert female inputs 204 and 206 of a partition adapter that holds optical fiber connectors 214 and 216. Gerhard's... Figure 4 Another embodiment is shown, in which the cleaning solvent / pressurized gas delivery system is arranged at an angle to the fiber optic end face 402 and includes a suction tube 304 and a microscope 500. See the description in column 10, row 26, etc.

[0014] The patents by Lytle and Gerhard disclose cleaning of fiber end faces without physical contact, but do require inserting a nozzle assembly into a connector or other structure associated with the fiber connector. Other patents disclose contact cleaning, where the swab or cloth makes physical contact with the end face. For example, U.S. Patent 7,401,374, issued July 22, 2008, to JSTourigny, and U.S. Patent 9,798,093, issued October 24, 2017, to JSTourigny (both assigned to the assignee of this application), disclose manually operated swab-like cleaning devices for cleaning fiber end faces disposed within connectors, couplings, or partition sockets. Patent 9,798,093 discloses a cleaning swab suitable for cleaning extended beam fibers. U.S. Patent 8,087,118, issued January 3, 2012, to K. Fujiwara, discloses a contact cleaning tool sometimes referred to as a “clicker.” Cleaning tool 1 (Figure 1) utilizes a "cleaning body," i.e., a cleaning cloth, which is dispensed from the supply spool 30 over the head member 23 and subsequently to the take-up spool 31. The head member 23 is inserted into the connector insertion port 71 of the optical adapter 70 (see column 13, rows 1-6 and Figures 7-9), and the cleaning head is rotated to clean the fiber end face by direct contact with the cleaning body (cloth). The cleaning head is advanced as needed to provide a new cleaning cloth. In this device, the advancement of the cleaning cloth is done mechanically and produces a clicking sound, hence this type of device is called a "clicker."

[0015] Many patent disclosures relate to apparatus and methods for cleaning fiber optic end faces. Here are a few examples. U.S. Patent 7,147,490, granted December 12, 2006, to GJ Gerhard (“Gerhard II”), discloses a fiber optic end face cleaning apparatus designed to enter the housing of an interface device and provide compressed air and solvent for cleaning, as well as vacuum lines for removing residual solvent. Gerhard II discusses the problem of residual solvent remaining in the bevels or other gaps of the housing, flowing back to the just-cleaned end face and contaminating it. The vacuum applied at the end of the cleaning cycle may not be able to remove residual solvent from these gaps, and therefore Gerhard II provides additional structures (retractable baffles) to attempt to prevent solvent from entering these gaps in the first place. See, for example, Column 12, Row 48 to Column 13, Row 2 of Gerhard II.

[0016] U.S. Patent Publication 2021 / 0101167A1, published April 8, 2021 by KMHill et al., discloses a compressed gas canister system for cleaning optical fiber end faces, comprising an interface tube 250 that must be inserted into a housing of the optical fiber. Figure 2A similar construction is shown in U.S. Patent 7,566,176 to S. Lytle et al., issued on July 28, 2009.

[0017] The following patent disclosures generally disclose injection devices. U.S. Patent 6,776,360, granted August 17, 2004, to J. Haruch et al., discloses a gun-like injection device comprising a reciprocating valve needle for controlling injection, as described, for example, in column 3, lines 52-67. Patent Publication US2007 / 0164130A1 (“Jackson”), published July 19, 2007, discusses utilizing the Coanda effect in a compound injection device to transfer lubricant on the outer surface of the device for mixing turbulence with a propellant fluid (e.g., compressed air) at the nozzle exit. See, for example, paragraphs

[0008] and

[0030] of Jackson's work, and... Figure 2 . Summary of the Invention

[0018] This invention utilizes the known Coanda effect to generate a precise flow of compressed air (or other suitable gas) and atomized solvent, conforming to the alignment surface and surrounding area of ​​the fiber optic endface to clean and dry the alignment surface and surrounding area. The Coanda effect is a known phenomenon that occurs when a free jet of fluid appears near a surface: the jet tends to “attach” itself to the surface and flow along it, which will be described more fully below. Compared to prior art cleaning devices and methods, this invention enables non-contact cleaning of fiber optic endfaces, whether the endface is contained within a recess of an adapter or exposed (i.e., not enclosed within the adapter). Non-contact cleaning is achieved by spacing the nozzle outlet of the cleaning device at a specific distance from the endface to be cleaned, as described below, and without requiring any part of the cleaning device to be introduced into the recess of the adapter. This is achieved by utilizing the Coanda effect to guide a jet of gas (e.g., air) carrying atomized solvent, followed by a subsequent jet of dry air, onto the connector endface surface to be cleaned. The cleaning apparatus and method of the present invention are particularly suitable for non-contact cleaning of the end face of an optical fiber clamp, which is used to mate an optical fiber when connection / disconnection capability is required.

[0019] The cleaning apparatus of the present invention includes a housing having a dispensing nozzle adapted to deliver a narrow jet or column of pressurized gas and atomize a solvent, such as air, carbon dioxide, nitrogen, or other suitable gas, within the narrow pressurized gas column. The housing is positioned to selectively guide the narrow pressurized gas column, as well as the column of pressurized gas and the narrow column of atomized solvent, toward an optical fiber end face or an extended beam lens to remove contaminants from the end face, regardless of whether the end face is included within an adapter. A method for cleaning an optical fiber end face includes the steps of: establishing and guiding a dispensed narrow pressurized gas column from a nozzle toward and in contact with the end face using a low-pressure region generated by utilizing the Coanda effect. The method further includes injecting a solvent into the pressurized gas by means of the low-pressure region established in the gas column by the Coanda effect. The low-pressure region atomizes the solvent into droplets, which mix with the pressurized gas in the narrow jet column to provide non-contact cleaning of the optical fiber end face. The method of the present invention also includes using the Coanda effect to deliver a column of pressurized gas, such as air, after the solvent flow has ceased to dry the end face.

[0020] According to the present invention, an apparatus comprising a needle valve nozzle is used, the apparatus being configured to induce a Coanda effect in a jet or column of pressurized gas and to selectively mix the atomized liquid solvent and the column of pressurized gas.

[0021] Although any suitable solvent composition may be used in the practice of this invention, the inventors have developed certain solvent formulations that are particularly useful in the practice of this invention. Unless otherwise specifically stated, the amounts of components in the solvent formulations disclosed herein are given as a weight percentage (“wt%”) of the component and represent the percentage of the component’s weight to the total weight of the components.

[0022] Specifically, according to one aspect of the invention, a method for cleaning the end face of an optical fiber is provided using a cleaning apparatus comprising a nozzle having a nozzle outlet, within which a needle plug is disposed, the needle plug having a decreasing cross-section in the outward flow direction through the nozzle outlet. The needle plug terminates at a tip facing the outside of the nozzle. The method includes the following steps: A compressed gas is flowed through the needle plug, through the nozzle, and through the nozzle outlet, the needle plug and nozzle outlet being configured to form a jet of ejected gas exiting from the nozzle outlet, the jet of ejected gas forming a depressurization region relative to ambient atmospheric pressure surrounding the depressurization region of the jet of ejected gas. The nozzle outlet is aligned with such an end face, and the tip of the needle plug is positioned approximately 0.25 inches to approximately 0.75 inches (0.64 to 1.91 cm) from such an end face. A liquid solvent upstream of the nozzle outlet is introduced into the compressed gas, thereby atomizing the solvent in the jet of ejected gas. The jet of ejected gas containing the atomized solvent is impinged on such an end face for a cleaning period of time. Subsequently, the introduction of solvent into the compressed gas is stopped, and the resulting jet of dry gas is impinged onto such end faces for a drying period of time to remove the solvent by evaporation accelerated by the depressurization zone, without applying a vacuum to or near such end faces.

[0023] Other aspects of the invention include one or more of the following aspects, alone or in any suitable combination. The cleaning time period can be from about 0.5 to about 2 seconds, and the drying time period can be from about 1 to about 4 seconds; the liquid solvent can have a vapor pressure of about 20 to about 25 kPa at 25°C and one atmosphere, a Kauri Butanol value of about 18 to about 44, and be non-flammable according to the ASTM D-56 closed-cup flash point test; the liquid solvent introduced into the gas jet can contain (a) 83 wt% hydrofluoroether, which contains 55 to 90 wt% methyl nonafluoroisobutyl ether and 10 to 45 wt% methyl nonafluorobutyl ether, (b) 10 wt% hydrofluoroether, which contains 90 wt% Z-isomer and 10 wt% E-isomer, and (c) 7 wt% heptane, and the solvent can contain less than 10 ppm of nonvolatile residues and less than 100 ppm of water.

[0024] In another aspect of the invention, the liquid solvent introduced into the gas jet may comprise 60 wt% of 1,1,1,3,3,3-hexafluoro-2-methoxypropane, 34.9 wt% of 1-chloro-2,3,3-trifluoroprop-1-ene, 5.0 wt% of acetone, and 0.10 wt% of nitromethane, wherein the solvent contains less than 10 ppm of nonvolatile residues and less than 100 ppm of water.

[0025] Another aspect of the invention provides a nozzle outlet that may include a gas outlet and a separate solvent outlet, and a needle plug may be disposed within the solvent outlet. The method further includes: moving the needle plug between an open position and a closed position, the open position opening the solvent outlet to dispense solvent into the jet gas stream, and the closed position stopping the dispensing of solvent into the jet gas stream; and moving the needle plug to the open position to initiate a cleaning period, and moving the needle plug to the closed position to terminate the cleaning period and initiate a drying period.

[0026] Other aspects of the invention include one or more of the following aspects, alone or in any suitable combination. The compressed gas may be selected from air, nitrogen, and carbon dioxide; the velocity of the jet of gas flowing through the needle plug is sufficient to impart a Coanda effect, thereby creating a depressurization zone. Attached Figure Description

[0027] Figure 1A It is a cross-sectional view of a sleeve end with an optical fiber end according to the prior art, wherein it has a flat end surface;

[0028] Figure 1B It is a cross-sectional view of a sleeve end with an optical fiber end according to the prior art, wherein it has a convex end surface;

[0029] Figure 1C It is a cross-sectional view of a sleeve end with an optical fiber end according to the prior art, wherein it has an angled end surface;

[0030] Figure 2 This is a perspective view of a connector fitting equipped with a sleeve end, based on existing technology;

[0031] Figure 3 It is a partial cross-sectional view of two sleeve ends of optical fibers according to the prior art, wherein the sleeve ends are used for connection to interconnect optical fibers;

[0032] Figure 4 It is a schematic cross-sectional view of a sleeve end with an optical fiber end according to the prior art, wherein an extended beam end surface is provided;

[0033] Figure 5 It is a schematic cross-sectional view of two sleeve ends of an extended beam optical fiber according to the prior art, wherein the sleeve ends are used for connection to interconnect the optical fibers;

[0034] Figure 6 yes Figure 5 A schematic cross-sectional view of one of the sleeve connectors;

[0035] Figure 7A It is a schematic diagram of the ambient air pressure acting on a jet of air or other gases;

[0036] Figure 7B yes Figure 7A A schematic diagram of an air jet passing through the surface of a curved or bent structure;

[0037] Figure 8 This is a schematic cross-sectional view of a nozzle according to an embodiment of the present invention;

[0038] Figure 9 This is a schematic cross-sectional view of a nozzle according to an embodiment of the present invention, which is positioned to clean the exposed end face of the optical fiber, i.e. the end face of the optical fiber that is not enclosed within the connector.

[0039] Figure 10 Is with Figure 9 The corresponding schematic cross-sectional view, but the nozzle is positioned to clean the fiber end face enclosed within the connector;

[0040] Figure 10A It is along Figure 10 A stereoscopic view intercepted by line AA; and

[0041] Figures 11-1 to 11-5B It is an inkblot image that reproduces a photograph of the fiber optic end face magnified 80 times, showing the contamination of the end face before and after cleaning with the method and apparatus of the present invention. Detailed Implementation

[0042] In fiber optic networks, single-mode glass fiber strands, approximately 8 micrometers in diameter, are connected by wrapping the strands in a protective sheath to form a cable and mating the two cable ends together. To do this, the two terminated ends of a single fiber strand are typically stripped from the sheath and bonded and encapsulated in the center of a rod-shaped clamp. This clamp provides an increased surface area for the fine polishing of the exposed end faces of the fiber strands. The clamp is typically made of ceramic, but can also be made of metal or plastic. The clamp usually conforms to standard sizes, most commonly having end faces with diameters of 1.25 mm, 1.6 mm, 2.0 mm, or 2.5 mm. Flat polished end faces are now rarely used due to signal issues associated with back reflection. To ensure good physical contact between the two connectors during mating, the most common end face geometry for single-mode connectors is polished into a convex curve. In modern fiber optic networks, the end face of the connector is polished into an arbitrary convex physical contact finished surface (“PC Finish”), where the end face is polished into a slightly curved convex or spherical profile. The minimum and maximum curvature is defined by Telecordia GR-326 (the most commonly used set of vendor-neutral specifications and standards) as having radii between 7 mm and 22 mm, or less commonly as a profile with an 8° angle (APC Finish). Both profiles ensure the desired glass-to-glass physical contact of the fiber strands when two connector end faces mate. This physical contact reduces light separation losses due to Fresnel reflections and reflected light at the joint. The connector is installed in various types of connector adapter housings, which, combined with the inner sleeve, allow for precise interconnection with similar devices, such as connectors via connectors or partitions, to ensure accurate alignment of the mated fiber strands.

[0043] The cleanliness of cable connections is a critical factor in maintaining peak signal communication performance. Mating connectors are highly susceptible to minute contamination at each adjacent end face of the optical fiber. Specifically, the optical transmission capability at the joint between two optical fibers can be significantly attenuated by tiny contamination deposits on the polished end surfaces of the fibers. Sources of this minute contamination include soot, dust, dirt, moisture, and other environmental pollutants, including oil, salt, and particles, which can be transferred through skin contact with technicians during connector manufacturing and assembly, cable installation, or field service work. Even small amounts of contamination in the form of tiny particles or tiny oil mists will significantly increase optical attenuation at the joint. With the increasing network traffic from the use of wavelength division multiplexing (WDM) technology, the need for clean fiber end faces is becoming increasingly important. Furthermore, with the increasing demand for signal transmission bandwidth in fiber optic communication systems, the cleanliness of fiber end faces becomes increasingly critical due to the increased laser power driving fiber signals. When a high-power laser strikes a tiny contamination patch on the fiber end face, the contamination patch may burn, leaving soot or burn marks on the fiber end face, which can significantly reduce signal transmission through the connection.

[0044] Therefore, it is essential to clean the connector end surfaces before the fiber ends mate with each other, and / or after they have become contaminated during normal use.

[0045] In single-mode fiber, the glass core diameter is only 8 micrometers, making meaningful inspection of the ferrule endface impossible without magnification. Specialized microscopes have been designed to visually inspect the endface before mating and confirm the removal of minute contaminants. Most inspection microscopes magnify the endface 200x to 400x, displaying the image on a small screen. To minimize operator error in determining fiber endface cleanliness, inspection microscopes typically employ software to confirm cleanliness using pass / fail results when inspecting according to industry standards (such as IEC 61300-3-35). Modern display microscopes are also capable of saving digital archives of images of cleaned connectors, documenting successful cleaning results for numerous individual connectors.

[0046] Pressurized gas / solvent cleaning devices (such as those described in the prior art above) are used to clean the fiber end faces mounted in recesses within adapter housings. They require nozzle insertion into the adapter and therefore must be uniquely sized to clean any 1.25mm, 1.6mm, 2.0mm, or 2.50mm connector. It is unlikely that a prior art cleaner designed for 2.5mm connectors can be used to clean 1.25mm connectors, and vice versa. Therefore, as part of their routine work, field technicians using prior art cleaners to clean connectors must be equipped with cleaners of various sizes to clean specific sizes and types of connectors. Furthermore, the necessary insertion of the nozzle into the adapter requires physical contact, which increases the risk of the cleaning device introducing or redistributing oil or dust contamination onto the fiber end faces.

[0047] Currently, there are multimode fiber optic connectors with core diameters of 50 or 60.5 micrometers, multi-fiber push-out (MPO) connectors (ideally suited for simultaneously mates with 8, 12, or 24 fibers of ribbon connectors), and various other fiber optic connector configurations with similar cleaning challenges. Although this paper discusses single-mode fiber optic connectors, the Coanda effect cleaning method described herein is well-suited for cleaning all types and configurations of fiber optic connectors and offers the same advantages as the single-mode connectors described herein.

[0048] Before discussing specific embodiments of the invention, an explanation of the Coanda effect is useful. The Coanda effect is named after the Romanian engineer and mathematician Henri Coanda. Named after Coanda, the Coanda effect describes the tendency of a jet of fluid to be ejected from an orifice to flow along and carry fluid from an adjacent surface (whether flat or curved), thus creating a region of lower pressure along the jet. The Coanda effect can be understood by analogy to the well-known Bernoulli principle, which states that a jet of rapidly moving air has lower pressure than nearby stationary or slowly moving air. An aircraft wing is curved at its top surface, so air must travel faster along the top surface than along the bottom surface, thus reducing the pressure acting on the top surface. The higher pressure generated on the bottom surface creates the "lift" that allows the aircraft to fly. (Reference) Figure 7A and Figure 7B This explains the Coanda effect. A jet G of air or other gas exiting from orifice O moves at a velocity higher than the surrounding atmosphere, which can be stationary. Therefore, according to Bernoulli's principle, the jet G has a pressure Pg lower than the pressure Pa of the surrounding atmosphere. Figure 7A In the diagram, the pressure of the ambient atmosphere (e.g., atmospheric pressure) is represented by the arrow Pa, and it can be seen that it acts over the entire outer circumference of the jet G. Conversely, as... Figure 7BAs shown, if the jet G is discharged near the surface S of the structure T, the structure T impedes the ambient air pressure Pa from acting on one side of the jet G. Therefore, the unimpeded ambient pressure Pa forces the jet G into contact with the surface S. Even if the surface S is as... Figure 7B As shown, bending or folding, the ambient pressure Pa also forces the jet G to follow the contour of the surface S. The Coanda principle is applied in various fields, such as airfoils (aerodynamics), gas burner torch heads, and thin-film blow molding. This invention utilizes the Coanda effect to direct, adhere to, and follow the contour of the sleeve end face and any surrounding enclosed structure of the fluid for cleaning and drying, without bringing the cleaning device into contact with the structure to be cleaned. To achieve the Coanda effect, care must be taken to precisely align the jet and maintain an appropriate distance between the nozzle from which the jet exits and the surface to be cleaned.

[0049] exist Figure 8 , Figure 9 and Figure 10 For the sake of simplicity, the common controls for controlling the flow rates of the gas and solvent, as well as the operation of the needle valve, have been omitted from the accompanying drawings. Such controls are well known in the art and are not part of this invention.

[0050] Cleaning device 100 according to an embodiment of the present invention Figure 8 The device includes a housing 102 with a dispensing nozzle 104 at one end. The dispensing nozzle 104 has two orifices: one orifice 106a located at the discharge end of a gas passage 106, and the other orifice 108a located at the discharge end of a solvent passage 108. The solvent orifice 108a is located at the center of the nozzle 104 and can be closed by means of a centrally located, movable, symmetrically shaped needle plug 110 having smooth sidewalls that slope towards a sharp point at the end of the needle plug. The needle plug 110 is generally positioned such that the solvent orifice 108a is in a closed position (not shown). A second external gas orifice 106a is adjacent to and concentric with the solvent orifice 108a. Figure 10A As shown, the cross-sections of orifices 106a and 108a are both circular.

[0051] The needle plug 110 is positioned at the outlet of the solvent channel 108, and (as shown) Figure 8 , Figure 9 and Figure 10 As shown (to the left), it is movable to close solvent channel 108, and (as shown) Figure 8 , Figure 9 and Figure 10 (As shown to the right) is movable to open solvent channel 108. This movement of the needle plug 110 is caused by... Figure 8 The double-headed arrow V indicates that the amount of solvent flowing is adjusted by the position of the needle plug 110 and the degree of opening between fully open and fully closed.

[0052] A stream of dried, filtered compressed air from compressed air source 112 flows through line 114 and through external air orifice 106a, parallel to the inclined sidewall of needle plug 110. The moving compressed air adheres to the inclined shape of the tip of needle plug 110, which protrudes beyond solvent orifice 108a, providing a Coanda effect that creates a low-pressure region originating from the tip of needle plug 110. Figure 8 , Figure 9 and Figure 10 The unnumbered dashed line represents the edge jet column 118. A low-pressure region surrounds the jet column 118 and is somewhat funnel-shaped. This low pressure causes a concentration of airflow velocity and shapes the airflow into a narrow jet column 118 that remains highly concentrated at a distance d from the pointed end of the needle plug 110, ranging from 0.25 inches to 0.75 inches (0.635 cm) to 1.905 cm. This allows the jet column 118 to be focused onto the exposed fiber end face for cleaning without physical contact, such as rubbing the end face with a cleaning cloth. Figure 9 The image shows a jet column 118 enclosed in a low-pressure region, which impacts the fiber end face 120 of the fiber optic male connector (i.e., plug 113).

[0053] The spacing between the nozzle 104 and the fiber end face during cleaning allows the concentrated cleaning jet column 118 to clean and dry the recesses in the adapter housing 122. Figure 10 The same cleaning nozzle can also clean the end face (female connector) of the fiber optic connector 113 that is not installed in the adapter, i.e., the fiber optic male connector 113 with fiber end face 120. Figure 9 ). Specifically, Figure 9 A fiber optic male connector 113 is shown, having a fiber end face 120 cleaned by a jet column 118. There is no physical contact between the cleaning device 100 and the connector 113. Figure 10 As shown, the concentrated jet column 118 can also be guided through the open end of the adapter housing 122 and reach the fiber end face 124 mounted within the recess of the adapter housing. An alignment sleeve 115 within the adapter housing 122 receives the male connector 113. Regardless of the end face's location, no physical contact with the end face 124 is required, nor is it necessary to insert the cleaning device 100 or any part thereof into the adapter housing 122. The fixing device that contacts the adapter housing and supports the cleaning device can be used to maintain precise positioning of the cleaning device relative to the adapter housing during cleaning cycles.

[0054] The Coanda effect can occur in both gases (e.g., air) and liquids. Therefore, high-purity, fast-drying solvent cleaners can be immediately injected into existing jet columns. This is achieved by opening the movable needle plug 110 to introduce solvent from the solvent source 116 through line 119 and out through the internal solvent orifice 108a. This forms a jet column 118 ( Figure 8 , Figure 9 and Figure 10 The low-pressure region is generated by the Coanda effect, causing the solvent to be immediately atomized into high-speed mist droplets within the jet column 118. The airflow and atomized solvent droplets combine to generate a high-speed jet column 118 containing the atomized mist, which can be directed to the fiber end face for non-contact mechanical-fluid cleaning. When the needle plug 110 is moved to its closed position (e.g., Figure 8 , Figure 9 and Figure 10 When the solvent flow is cut off (as shown to the left), the jet column 118 is dry and is used to induce the evaporation of residual solvent. The reduced pressure within the jet column 118 caused by the Coanda effect promotes solvent evaporation and eliminates the need for applying a vacuum to remove residual solvent, as required by many prior art devices.

[0055] Figures 8 to 10 The cleaning device dispensing nozzle 104 is one embodiment of the nozzle of the present invention, which, when properly spaced from the fiber end face, generates the desired Coanda effect jet by appropriately combining pressurized gas and solvent jets. Variations can be made to the illustrated dispensing nozzle design, which will also provide a similar Coanda effect.

[0056] Tests using a Coanda-induced low-pressure airflow column showed that a continuous cleaning process of 5 to 10 seconds can effectively clean minute dust, oil, or a combination of dust and oil residues over the entire area of ​​the fiber end face, as shown below.

[0057] Example 1

[0058] a.) The dispensing nozzle is positioned between 0.25 inches and 0.75 inches (0.6335 cm to 1.905 cm) from the fiber end face, with the center of the air / solvent cleaning jet aligned with the apex (or center) of the polished fiber end face. Since the end face clamp diameter can be as small as 1.25 mm ("mm"), and the end face can be recessed within the adapter housing, the nozzle is mounted to maintain proper alignment of the cleaning jet with minimal or no movement of the nozzle and cleaning jet during cleaning cycles.

[0059] b.) The cleaning process begins with a one-second ramp of compressed airflow, which is distributed by nozzles to create a Coanda effect low-pressure airflow away from the end of a movable needle of a symmetrical shape, thereby ensuring a constant and concentrated jet of high-pressure air.

[0060] c.) By moving the needle to the open position, a timed injection of solvent, lasting 1 to 2 seconds, can be achieved into a low-pressure region established by the Coanda effect airflow, where the end of the symmetrically shaped needle exits. The low pressure causes the solvent to be immediately atomized into a high-speed mist of tiny droplets within the concentrated airflow column. The total amount of solvent dispensed in a 1 to 2-second timed injection is approximately 24 to 55 microliters.

[0061] d.) After 1 to 2 seconds, the injection of solvent into the gas flow is stopped by moving the needle to the closed position, while the concentrated gas flow column continues for the last 3 to 5 seconds, thereby exposing the end face and surrounding area to the high-speed Coanda effect gas flow to rapidly evaporate the dispensed atomized solvent and dry the end face and surrounding area.

[0062] Example 2

[0063] To reduce cleaning cycle time, tests showed that the following timed cycle provided effective cleaning while reducing the total cleaning cycle time by 1 second. The cleaning process is as follows.

[0064] a.) Positioning and dispensing nozzles (e.g.) Figure 8 , Figure 9 and Figure 10 The nozzle 104 in the middle is such that when the cleaning cycle begins, the jet emitted from the nozzle orifice is guided to the connector end face.

[0065] b.) Initiate the compressed air flow and simultaneously move the needle plug to the open position to dispense solvent from the nozzle, thereby establishing a Coanda effect airflow of high-pressure air injected with solvent from the end of a symmetrically shaped movable needle. The solvent is instantaneously atomized into a high-speed mist of tiny droplets in the concentrated airflow through the low-pressure region established by the Coanda effect airflow.

[0066] c.) After 1 second, the syringe plug moves to the closed position, thereby stopping the flow of solvent into the gas stream. The total amount of solvent dispensed in a 1-second timed injection is approximately 10 to 20 microliters.

[0067] d.) When the needle is in the closed position, the concentrated high-pressure airflow continues for an additional 2.5 seconds, exposing the end face and surrounding area to the high-speed Coanda effect airflow, thereby rapidly evaporating the atomized solvent and drying the end face and surrounding area.

[0068] e.) The cleaning cycle is complete after 3.5 seconds.

[0069] Although any compressed gas (such as nitrogen or carbon dioxide) can work in this application, the cleaning tests described in Examples 1 and 2 used filtered, dry compressed air generated by a small portable compressor that delivered air at a pressure of 17 PSIG and an airflow volume of 8.5 liters per minute.

[0070] This article illustrates a method for achieving an ideal Coanda effect cleaning process using a compressed air supply specification. The characteristics of the Coanda effect airflow are controlled by the geometry of the dispensing nozzles and needles, surface conditions, and variations in air pressure and airflow volume. It should be understood that other nozzle designs, air pressures, and airflow volumes can be used and adjusted as needed to achieve the Coanda effect.

[0071] The high-purity solvent used in this cleaning method was selected to have a rapid drying rate for all components. Suitable formulations are as follows, with the amount of each component expressed as a weight percentage (“wt%”) of the total weight of the solvent.

[0072] Example 3

[0073] 60wt% -- 1,1,1,3,3,3-hexafluoro-2-methoxypropane (CAS 13171-18-1)

[0074] 34.9 wt% -- 1-Chloro-2,3,3-trifluoroprop-1-ene (CAS 1263679-68-0 and 1263679-71-5)

[0075] 0.5.0 wt% -- Acetone CAS 67-64-1

[0076] 0.1wt% -- Nitromethane CAS 75-52-5

[0077] Boiling point: 52℃ (126°F)

[0078] NVR: <10ppm

[0079] Moisture content: <100ppm

[0080] Steam pressure (calculated): 33.7 kPa

[0081] Specific gravity: 1.33g / ml

[0082] Flammability: The solvent formulation described above is non-flammable according to the ASTM-D56 Closed Cup Flash Point test. However, alternative chemicals with similar physical properties will produce similar results when using Coanda effect cleaning processes.

[0083] The solvent has electrostatic dissipation properties, eliminating existing triboelectric charges on the end faces, or the accumulation of static charges that may be generated by the pressurized airflow containing dust particles removed during cleaning. Surfaces charged at 4,000–5,000 volts before cleaning have been shown to drop to zero volts upon completion of the aforementioned cleaning cycle using an ACL Staticide Electrostatic Locator meter, model 300B.

[0084] Because the cleaning method of the present invention does not involve any wiping or frictional contact with the end face, no triboelectric charge can be generated on the fiber end face through cleaning. Furthermore, the use of solvents with electrostatic dissipation properties helps to avoid the generation of triboelectric charge due to other reasons, as the solvates dissipate such charge. The cleaning process of the present invention thus eliminates triboelectric charge that may already be present on the plug, end face, and associated connector components. Triboelectric charge can be generated during the insertion and removal of the plug from the adapter housing for inspection or cleaning. By eliminating static charge across the entire end face and directly associated areas, this cleaning process eliminates the possibility of electrostatically induced dust particle migration after connector plug mating.

[0085] Because the dispensing nozzle is positioned at a distance of 0.25 inches to 0.75 inches (0.635 cm to 1.905 cm) from the fiber end face ( Figure 10 Therefore, the nozzle does not need to be custom-sized to fit a specific end face size. This means that a cleaning nozzle of one size can clean a wide range of connector sizes from 1.25mm to 2.5mm, as well as other commonly used connector types and sizes. It should be noted that the specific distance from the outlet nozzle to the end face is measured from the end of the pin plug 110 to the end face, such as... Figure 8 , Figure 9 and Figure 10 The distance d in the figure is shown.

[0086] Because the cleaning nozzles are spaced apart from the fiber endface during cleaning, the cleaning process of this invention cleans 100% of the endface, regardless of polishing, curvature, or endface geometry. This 100% cleaning prevents the presence of contamination on the outer area of ​​the endface diameter, which can be detected by the mirror software indicators but subsequently obstructs the signal by migrating to the vertices of the two mating fibers in the adapter.

[0087] For male and female connectors, trace amounts of end-face contaminants are carried away from the end face and away from the connector by a concentrated cleaning jet column; during the drying phase of the cleaning cycle, the contaminants are harmlessly carried away by the airflow and / or evaporated with the solvent.

[0088] In the slower cleaning cycle of Example 1, the amount of atomized solvent droplets dispensed was 24 to 55 microliters, while only 10 microliters were used in the faster cleaning cycle of Example 2. The small amount of solvent used during the cleaning process evaporates rapidly as part of the drying process; no liquid is present on adjacent surfaces to flow back to the end face after cleaning. Furthermore, no solvent leaks from the cleaned end face adapter to adjacent connectors, other adapter housings, or communication / electronic equipment located near the connector adapter assembly. The plug and end face are dried, cleaned, and ready for immediate use after cleaning.

[0089] As mentioned above, the more widely used contact cleaning devices in the industry are commonly referred to as "clickers." Using this prior art clicker as a benchmark for comparing cleaning performance, Example 4 below shows the results of a cleaning test comparing the results of Coanda effect cleaning with the benchmark "clicker" cleaning results. The cleaning test results listed in the table below were performed on a 1.25mm, LC ("Lucent connector") type connector, which is considered the most difficult connector to clean due to its small end-face diameter. The Lucent connector is the fiber optic industry name for a 1.25mm connector first developed by Lucent Technologies.

[0090] Example 4

[0091] Due to the lack of standardized cleaning testing methods in the industry, the tests documented below were conducted under controlled laboratory conditions using methods created by MicroCare Critical Cleaning Laboratory, New Britain, Connecticut, a laboratory maintained by an affiliate of the applicant. Cleaning results were examined using a Viavi FVDi-2080 inspection microscope with FMA-LC adapter accessories. Results were determined using Viavi Fiber ChekPRO software programmed according to IEC-61300-3-35, Ed 2.0; single-mode fiber optic ultrapolished connectors (SM UPCs) were classified as pass / fail.

[0092] Testing techniques.

[0093] 1. Clean, inspect and confirm that the end face of the 1.25LC object is completely clean, and visually confirm the end face "pass" result using inspection mirror software, without contamination or scratches.

[0094] 2. Contaminate known clean 1.25LC end faces with Arizona Road Dust to replicate particulate contaminants, or with Artificial Sebum to replicate human skin oil formulated according to ASTM D4265-14. Methods for implementing contaminants were developed to provide consistent implementation of each contaminant type for each end face test, minimizing variables in the quantity and density of contaminants on the end faces prior to cleaning tests.

[0095] 3. Cleaning method test:

[0096] a. Brand #MCC-CCU125, try full activation once per cleaning cycle.

[0097] b. IBC brand cleaner H125#12910, try it once for each cleaning to fully activate.

[0098] c. Coanda effect, based on a 6-second cycle for each cleaning attempt, the fiber end face is fixed to the dispensing nozzle ( Figure 9 At the center of 104), 0.25 inches from the cleaning nozzle. Figure 9 (The distance d in the text is 0.25 inches). It should be noted that the cleaning results obtained with a 3.5-second cleaning cycle, as described elsewhere in this article, are similar to those obtained with a 6-second cleaning cycle in Example 4.

[0099] 4. After the first cleaning attempt, use the inspection mirror software to determine the "pass / fail" result. If the first attempt is "pass", no additional cleaning is required. If it is "fail", repeat the cleaning and inspection with the mirror on the same end face. Each individual test should not exceed three (3) cleaning attempts in total.

[0100] 5. If the cleaning result is "failed" after three (3) attempts, it shall be included in the "Average number of cleaning attempts" column and the reason for failure shall be noted.

[0101] 6. For each "pass" result determined by the software on the end face, a visual inspection of the inspection mirror image was performed to confirm, through the software, under which of the following conditions the end face was considered a "pass":

[0102] a. The end face passed each software-allowed value, but the edges of the end face were not completely cleaned.

[0103] b. Scratches or other linear defects appear on the end face.

[0104] c. The end face passed each software test, and the visual inspection on the image screen showed that the end face was "completely clean" with no visible residue. Completely clean means that all contaminants from the end face to the outer edge have been removed.

[0105] 7. Each cleaning method was tested 10 times, and the results are shown in Table 1.

[0106] Table 1

[0107] 1.25mm male end face

[0108] Cleaning data

[0109]

[0110] Cleaning results; inspection microscope images

[0111] Figures 11-1 to 11-5B This is an inkblot image that reproduces an 80x magnified photograph of the end face of a 1.25mm LC connector. These end faces were cleaned and tested according to the methods detailed above.

[0112] Figure 11-1

[0113] Clean end faces, free of contaminants or defects. This is the ideal end face cleanliness condition for the connector before mating and interconnection within the adapter housing. This is the state of each connector before each of the aforementioned cleaning tests.

[0114] Figure 11-2A

[0115] The end face with Arizona road dust before cleaning with a CCU125 clicker.

[0116] Figure 11-2B

[0117] End face with Arizona road dust after cleaning with CCU125. Passed through each inspection lens software. Note that the apex (center) of the end face is clean; however, the presence and concentration of particles increase in the area furthest from the apex.

[0118] Figure 11-3A

[0119] The end face with Arizona road dust was cleaned using the Coanda effect.

[0120] Figure 11-3B

[0121] The end face, cleaned using the Coanda effect and exposed to Arizona road dust, passed every inspection software test with no residual dust or contaminants. Completely clean.

[0122] Figure 11-4A

[0123] Clean the end face with sebum using a CCU125 clicker.

[0124] Figure 11-4B

[0125] The connector end face, which had been cleaned with a CCU125 clicker, contained sebum. It passed each inspection software test, but only the vertex area of ​​the connector was cleaned. The outer edges of the connector remained uncleaned because the convex curvature of the end face prevented complete contact between the end face and the cleaning tip of the clicker.

[0126] Figure 11-5A

[0127] Use the Coanda effect to clean the end face that previously had sebum.

[0128] Figure 11-5B

[0129] The end face, which had been cleaned using the Coanda effect and contained sebum, passed through each testing software and the entire end face was cleaned down to the outer edge.

[0130] Example 5

[0131] A particularly useful solvent has the following composition.

[0132] 83 wt% HFE-7100: hydrofluoroether, which comprises:

[0133] 55 to 90 wt% of isobutyl isomer: CAS#163702-08-7, methyl nonafluoroisobutyl ether

[0134] 10 to 45 wt% butyl isomer: CAS#163702-07-6, 10 wt% methyl nonafluorobutyl ether Asahi AS300 hydrofluoroether, which includes:

[0135] 90 wt% Z isomer: CAS#1263679-68-0

[0136] 10 wt% E isomer: CAS#1263679-71-5

[0137] 7wt% heptane: CAS#142-82-5

[0138] The physical properties of this solvent are as follows.

[0139] Boiling point: 56℃ (132°F); recorded during fractionation. Boiling point indicates the rate at which the fluid dries.

[0140] Non-volatile residues (“NVR”): less than 10 ppm, collected via ASTM D2109.

[0141] This is crucial because the solvent needs to be kept at high purity at all times, as the contaminants we are removing are minute. If the NVR is higher than 10 PPM, there is a risk of adding minute contaminants to the area to be cleaned. Moisture content is below 100 ppm; collected via ASTM D3401 using a Karl Fischer titrator.

[0142] Calculated vapor pressure: 24.7 kPa. (This vapor pressure was calculated using the mole fractions and vapor pressures of the three components at 25°C.)

[0143] Tests show that the ideal vapor pressure is approximately 24.7 kPa, for example, approximately 25 kPa. This plays a role in the rate of solvent evaporation.

[0144] If the vapor pressure of the cleaning fluid is more than 20% lower than approximately 25 kPa, the fluid will evaporate more slowly, meaning that the drying time after cleaning will be too long.

[0145] The slowly drying solvent will migrate back to the end face after cleaning, potentially bringing contaminants back to the end face.

[0146] Slow-drying solvents can also migrate to connectors that are being cleaned nearby. This poses a risk when connectors are densely packed in a rack and close to other connectors.

[0147] If the vapor pressure is more than 20% higher than approximately 25 kPa, this will cause the solvent to dry too quickly. In other words, the solvent evaporates too quickly in the high-speed Coanda gas flow, resulting in insufficient amount of solvent to properly clean the connector end face.

[0148] Specific gravity: 1.39 g / ml; measured with a hydrometer at 25°C. 1.39 is relative to water.

[0149] A higher specific gravity makes a solvent denser and allows it to float tiny contaminants off a surface via buoyancy. For example, oak (a relatively dense wood) has a specific gravity of 0.75, meaning that oak dust / particles, as well as similar construction dust, easily float in such a solvent. A relatively heavier solvent is advantageous for cleaning smaller amounts of tiny contaminants on a surface in a short time.

[0150] The above properties are useful for solvents used in the practice of this invention.

[0151] Example 6

[0152] A test was conducted to demonstrate the effect of the Coanda effect airflow on solvent drying time. A steady-state air supply delivered a clean, dry airflow through a dispensing device vertically positioned above the center of the vessel in the test fixture described below. Two different dispensing devices were used alternately to deliver airflow at the same pressure and velocity to dry 10 μL of solvent. The only difference between the two methods of airflow delivery was that in one set of tests, air flowed directly onto the solvent from the orifice of a conventional injection cannula, while in the other set of tests, air flowed onto the solvent from an orifice incorporating a needle valve to establish the Coanda effect airflow. Figure 8 , Figure 9 and Figure 10 As shown, the needle is positioned in the orifice, but only dry air flows through it.

[0153] Test Details

[0154] The test used a fixture to vertically position the air delivery device 0.250 inches (0.635 cm) above a vessel-shaped recess centered at the bottom of a shallow cylindrical cup with an outer diameter of 0.585 inches (1.486 cm) and an inner diameter of 0.511 inches (1.298 cm), thus providing a circumferential wall with a thickness of 0.074 inches (0.188 cm) and a height of 0.197 inches (0.500 cm). The vessel formed at the bottom of the cup has an outer diameter of 0.289 inches (0.734 cm) and a depth of 0.028 inches (0.071 cm).

[0155] Then, using a Fisherbrand precision dosing syringe described below, 10 microliters (“μL”) of the solvent from Example 5 was placed into the vessel. The following equipment was used in the solvent evaporation test. To deliver the gas flow to dry the solvent in the vessel, we used a syringe with a standard round cannula for non-Coanda gas flow, and a syringe with a dosing device as described below. Figure 8 , Figure 9 and Figure 10 The needle valve is configured as shown with a conventional articulated air brush to provide coanda airflow. To minimize as many variables as possible, the syringe cannula orifice (for airflow) is sized as closely as possible to the airflow orifice in the air brush. The syringe orifice diameter is 0.0095 square inches, and the air brush orifice diameter is 0.0041 square inches. The larger diameter of the conventional cannula gives it some advantages over the air brush. The air velocity dispensed from the syringe is controlled to match the air velocity exiting from the air brush at 4.5 meters per second (“m / s”).

[0156] The instrument used to confirm the airflow was an Air Science-Air Velocity Control Instrument. The device used to dispense 10 microliters of solvent was a Fessell single-injection pump model 78-0100L. The ambient temperature during the test was 65°F (18.3°C) on one test day and 73°F (23.9°C) on another test day. Therefore, the evaporation time was shorter on the warmer day, but the relative evaporation rate was the same on both days.

[0157] A precise dose of 10 μL of solvent was deposited in a vessel, and then the compressor was turned on, blowing air perpendicularly to the solvent surface directly onto the solvent using a delivery device. The total drying time (evaporation of all 10 μL of solvent) is the average of the times measured by both methods over at least 20 test cycles using a syringe and an air brush. The results are as follows:

[0158] Table 2

[0159]

[0160] In summary, the time difference is significant. Table 2 above shows that the Coanda effect gas flow dries 10 μL of solvent in a vessel on average about 3 seconds faster than air from a syringe, and about 37% faster than a non-Coanda effect gas flow. This test demonstrates that the Coanda effect gas flow establishes conditions (directional gas flow and low-pressure region) that significantly increase the drying time of the solvent.

[0161] According to the present invention, the solvent is atomized in the gas stream via the Coanda effect, which further accelerates the drying time compared to using a slug with unatomized solvent. The Coanda effect plays a crucial role in achieving the cleaning cycle, which in practice lasts only about 3.5 seconds in total. The cleaning cycle involves a delivery of compressed air (or other suitable gas) for about one second, followed by a cutoff of the solvent flow to provide approximately 2.5 seconds of dry air or other gas. The short cleaning cycle time is critical. Fiber optic cable connectors can include many individual fiber end faces, for example, up to 800 male connectors connected to 800 female connectors in a cabinet. Therefore, up to 1600 end faces require cleaning. Even saving a few seconds per end face results in significant time savings.

[0162] The invention has been described in detail with reference to specific embodiments thereof, but these specific embodiments are not intended to be construed as limiting the scope of the invention.

Claims

1. A method for cleaning the end face of an optical fiber using a cleaning apparatus, the cleaning apparatus comprising a nozzle having a nozzle outlet, a needle plug disposed within the nozzle outlet, the cross-section of the needle plug decreasing in the direction of outward flow through the nozzle and terminating at a tip facing outward from the nozzle, the method comprising: Compressed gas is passed through a needle plug, a nozzle, and a nozzle outlet, the needle plug and the nozzle outlet being configured to form a jet of ejected gas exiting from the nozzle outlet, the jet of ejected gas forming a pressure-reducing region relative to ambient pressure, the pressure-reducing region surrounding the jet of ejected gas. Align the nozzle outlet with the end face and position the tip of the needle plug 0.25 inches to 0.75 inches from the end face; A liquid solvent upstream of the nozzle outlet is introduced into the compressed gas, thereby atomizing the solvent in the jet of the ejected gas. The jet of gas containing atomized solvent is applied to the end face for a prolonged cleaning period; and Stop introducing the solvent into the compressed gas and allow the resulting dry gas jet to impinge on the end face for a drying period of time to remove the solvent by evaporation accelerated by the depressurization zone, without applying a vacuum on or near the end face.

2. The method according to claim 1, wherein the cleaning time period is 0.5 to 2 seconds and the drying time period is 1 to 4 seconds.

3. The method according to claim 1 or claim 2, wherein the liquid solvent has a vapor pressure of 20 to 30 kPa at 25°C and one atmosphere, a corybutanol value of 18 to 44, and is non-flammable according to the ASTM D-56 closed-cup flash point test.

4. The method according to claim 1 or claim 2, wherein the liquid solvent introduced into the gas jet comprises: (a) 83 wt% of hydrofluoroether, comprising: 55 to 90 wt% of methyl nonafluoroisobutyl ether and 10 to 45 wt% of methyl nonafluorobutyl ether; (b) 10 wt% of hydrofluoroether, comprising: 90 wt% of the Z-isomer and 10 wt% of the E-isomer; and (c) 7 wt% heptane, The solvent contains less than 10 ppm of non-volatile residues and less than 100 ppm of water.

5. The method according to claim 1 or claim 2, wherein the liquid solvent introduced into the gas jet comprises 60 wt% of 1,1,1,3,3,3-hexafluoro-2-methoxypropane, 34.9 wt% of 1-chloro-2,3,3-trifluoroprop-1-ene, 5.0 wt% of acetone and 0.10 wt% of nitromethane, said solvent comprising less than 10 ppm of nonvolatile residues and less than 100 ppm of water.

6. The method of claim 1 or 2, wherein the nozzle outlet comprises a gas outlet and a separate solvent outlet, and the needle plug is disposed within the solvent outlet, the method further comprising: The needle plug is moved between an open position and a closed position, the open position opening the solvent outlet to dispense solvent into the jet gas stream, and the closed position stopping the dispensing of solvent into the jet gas stream; The process includes moving the needle plug to the open position to initiate a cleaning period, and moving the needle plug to the closed position to terminate the cleaning period and initiate a drying period.

7. The method according to claim 1 or 2, wherein the compressed gas is selected from the group consisting of air, nitrogen and carbon dioxide.

8. The method according to claim 1 or 2, wherein the velocity of the jet of gas flowing through the needle plug is sufficient to induce the Coanda effect to generate the decompression region.

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