US3644953A

US3644953A - Sheet-cleaning apparatus

Info

Publication number: US3644953A
Application number: US44317A
Authority: US
Inventors: Robert W Christiansen
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1970-06-08
Filing date: 1970-06-08
Publication date: 1972-02-29
Anticipated expiration: 1989-02-28
Also published as: DE2128276B2; FR2099750A5; JPS5528750B1; DE2128276C3; GB1350927A; DE2128276A1

Abstract

An inexpensive manually operated device for thoroughly cleaning photographic film negatives. The device includes two pneumatically inflated cylinders that press two lengths of wiping cloth into even and intimate contact with opposite surfaces of a negative passed between the lengths of cloth. The device blows ionized air across the negative after it is wiped clean to neutralize any static electrical charges present on the negative.

Description

U nitedStates Patent 1151 3,644,953 Christiansen 1 Feb. 29, 1972 [54] SHEET-CLEANING APPARATUS 2,514,321 7/1950 Fekete ..68/244 1,927,284 9/1933 Howell ..352/l30 X [72] lnventor. Robert W. Chrlstlansen, Hudson, Wis. 3,441,971 /l969 Gowdey "/210 R [73] Assignee; Minnesota Mining and Manufacturing 3,453,681 7/1969 Wiederhold ..l5/ X Company, St. Paul, Minn. Primary Examiner-Leon G. Machlin [22] Flled: June 1970 Attorney-Kinney, Alexander, Sell, Steldt & Delahunt [2]] Appl. No.: 44,317

[57] ABSTRACT 52 us. (:1 ..1s/1.s 15/100 352/ An inexpensive manually operated device for thoroughly [5 H [nL Cl B68) 11/00 cleaning photographic film negatives. The device includes two [58] Field 4 152, 153 pneumatically inflated cylinders that press two lengths of wip- 34 95, 9 100 68 244; 352 130 ing cloth into even and intimate contact with opposite surfaces 5 I 95 l l l of a negative passed between the lengths of cloth. The device [56] References Cited blows ionized air across the negative after it is wiped clean to neutralize any static electrical charges present on the nega- UNITED STATES PATENTS five 3,128,492 4/1964 Hanscom et al. ..15/ 100 X 7 Claims, 2 Drawing Figures SHEET-CLEANING APPARATUS This invention relates to the cleaning of sheet material and in one aspect to a cleaning apparatus for removing fine dust and other foreign materials from nonconductive sheet material such as photographic film materials which are to be printed.

Since photographic negatives comprise dielectric or nonconductive material, static electrical charges are easily developed on their surfaces during handling and these charges are not easily removed. Static electrical charges on a negative tend to attract dust from the ambient atmosphere or surrounding surfaces and this dust must be completely removed before printing, especially where enlargements are to be made, as any dust particles on the negative will show as an imperfection on the print.

Two prior art devices for removing dust from a film are shown in U.S. Pat. Nos. 3,128,492 and 3,117,333. These devices utilize two brushes positioned in opposed relationship with one on each side of a path to remove dust from both surfaces of a negative passed between them. These devices also provide ionized air at the brushes from a corona discharge type source to neutralize static electrical charges on the negative after it is cleaned. These devices have several disadvantages. First, the brushes used may tend to scratch the surfaces of photographic negatives. Additionally, the high voltage potential used to ionize air must be generated and must be properly shielded to prevent operator contact, so that these vides intimate contact between a lint-free wiping cloth and a web to be cleaned moving across the device by using a vacuum to urge the web down upon a section of wiping cloth extending over a cleaning head. This application also discloses a nuclear means for removing static electricalcharges from a cleaned plastic web, which comprises polonium enclosed in small ceramic particles attached to a bar to provide a safe source of alpha particle emission which may be disposed close to the web to ionize the air at the surface of the web.

While the device of the copending application very effectively removes particles, even particles microns in size or smaller, the use of this device to clean manually moved negatives, as opposed to continuous webs for which it was designed, is impractical. The disclosed device cannot be made compact enough to conveniently clean a manually moved negative in one pass. When this device is used to clean both sides of a web, the two cleaning heads required are not disposed opposite each other because a surface of the web to be cleaned must move toward the cleaning head disposed adjacent to it. Thus, positioning two cleaning heads and an ionizing source to define a path for a negative, to be cleaned may cause the path to be longer than the negative itself, and manual movement of a negative through such a path becomes difficult.

Prior art devices comprising two parallel supports positioned adjacent each other with two sections of wiping cloth passing between them have also been used for cleaning sheets or webs as is shown in U.S. Pat. Nos. l,927,284 and 1,857,633. In this type of device the supports are generally planar and are mechanically biased toward each other in an attempt to provide the needed intimate contact between the two sections of wiping cloth and both sides of a sheet or web passed therebetween over a relatively large contact area on the sheet or web. With these devices, however, it is difficult to obtain the light intimate contact between the cloth and both sides of the negative which is needed for thorough cleaning. Also, when mechanical biasing means are used the pressure tends to be irregular between the cloths and surfaces of the negative due to irregularities in the supports or in the negative.

When the supports are biased toward each other with sufficient pressure to completely clean a negative, some areas of the negative may be under such great pressure that scratching of the negative may result.

The present invention provides an inexpensive, compact and easily used means for completely cleaning both sides of a negative manually passed between two sections of wiping cloth.

The present invention also provides a safe means for neutralizing static electrical charges on the negative so that the negative will not attract dust after it has been cleaned.

The present invention provides a cleaning apparatus for removal of dust and other foreign objects from a sheet material moved through the apparatus. The apparatus includes a pair of inflatable support members having flexible semicylindrical walls positioned parallel to and in opposed relationship to each other to define opposed narrow support edges at a nip therebetween two lengths of soft lint free wiping cloth extending partially around and between the adjacent walls of the support members. The opposed surfaces of the cloth positioned between the support edges of the support members define part of a path through which a sheet to be cleaned may be passed. Pressure means are also provided which afford fluid pressure against the flexible walls for urging them toward each other to urge the opposed surfaces of the lengths of cloth toward each other with essentially an equal pressure distribution axially along the support edges when the walls and the lengths of cloth are separated from each other by the passage of a sheet therebetween.

The present invention also provides a manual means for changing the sections of wiping cloth positioned between the cylinders.

The invention will further be described with reference to the accompanying drawings wherein like members refer to like parts in the several views and wherein:

FIG. 1 is a top plan view of a negative-cleaning device constructed according to the present invention;

FIG. 2 is an elevational front view partially in section taken generally along the line 22 of HG. 1.

Referring now to the drawing there is shown an apparatus 10 embodying the present invention in which is positioned a photographic negative 9 being cleaned. The apparatus 10 comprises a base in the form of a pan ll having a lip 12 about its edge upon which is supported a plate 14 which comprises the main support member for the apparatus 10. The pan II is a plastic molding, and is provided with a pair of handles 16 to provide ease of portability for the apparatus 10.

The apparatus 10 includes cleaning means comprising a sec tion of wiping cloth on either side of a path for a photographic negative 9 to be cleaned. A pair of

first rollers

18 and 19, and a pair of

second rollers

21 and 22 are rotatably mounted on the plate 14. Two supplies of wiping cloth, designated as 24 and 25, are provided. The wiping cloth 24 is wound upon the

rollers

21 and 18 and has a length of the cloth extending therebetween, while the cloth 25 is wound upon and extends between the

rollers

19 and 22. The extended lengths of

wiping cloth

24 and 25 pass between a pair of tubular support members or inflatable tubes 27 and 28. The adjacent surfaces of these extended lengths of

cloth

24 and 25 define the path for a photographic negative 9 to be cleaned.

The cleaning means includes pressure means for bringing narrow sections of wiping cloth into complete intimate contact with the surfaces of a negative 9 to be cleaned. The tubes 27 and 28 are closed at their uppermost ends and are hollow. The walls of the tubes 27 and 28 are thin and are formed of a soft flexible material, for example, 0.032 inch thick, 70 durometer polyvinyl chloride. The tubular members 27 and 28 are clamped to a pair of flanges 30 formed around a pair of holes 32 in the plate 14. Housed in the pan 11 is a centrifugal blower and motor assembly 35 which draws its air supply through an orifice 37 formed in the sidewall of the pan 11. The blower 35 discharges its air through a duct 38 which connects the outlet of the blower 35 with the two holes 32. Thus, when the blower 35 is operating the interior of the tubes 27 and 28 are slightly pressurized pneumatically, for example, to a pressure of A inch of water above atmospheric pressure. The opposed portions of the wall in the nip between the tubes 27 and 28 define opposed narrow support edges for narrow sections of the lengths of

cloth

24 and 25.

The cleaning means also includes support means to prevent the two tubes 27 and 28 from moving away from each other when they are pressurized. As illustrated, a pair of

curved plates

41 and 42 are attached at one end to the plate 14 and are positioned to support a section of the periphery of the tubes 27 and 28 opposite the adjacent surfaces of the tubes 27 and 28. Thus, essentially an equal pressure distribution will be maintained axially along the narrow support edge so that the narrow sections of the wiping cloths 24 and positioned between the tubes 27 and 28 will conform to and will be pressed into even intimate contact with a negative 9 moved therebetween so that thorough cleaning of the negative 9 will occur.

Means are also provided to neutralize static electrical charges on a cleaned negative after the negative is wiped clean by contact with the sections of

wiping cloth

24 and 25. An orifice 45 is formed in the plate 14 adjacent one edge of the path and communicates with the duct 38 so that the pressurized air from the blower will be blown laterally across both surfaces of a negative 9 moved between the tubes 27 and 28. A quantity of polonium encapsulated in particles or spheres as described in US. Patent No. 3,147,225 is disposed in the outlet of the blower 35 (not shown). The air used to pressurize the tubes 27 and 28 and which is blown across a negative 9 is ionized because of alpha particles emitted from the polonium source and will essentially remove static electric charges from both surfaces of the negative. The orifice 45 along with the blower 35 is sized to provide the proper pressure in the tubes 27 and 28 and to blow a sufficient quantity of ionized air across the surfaces of the negative so that essentially all static electrical charges present will be neutralized.

Thus, the apparatus 10 provides a manually operated means for cleaning a photographic negative which is convenient to use and which neutralizes static electrical charges on a cleaned photographic negative.

Means are provided for changing the sections of the

cloth

24 or 25 which are brought into contact with the negative being cleaned. The changing means or cloth advancing device comprises a train of

gears

52, and 53 which are joumaled on the plate 14 and which operably connect a gear 51 attached to the shaft of the roller 22 to a gear 54 attached to the shaft of the roller 21. The gear 53 serves as a thumb wheel and extends through the side of the pan 11. Thus, when it is desired to advance the section of cloth brought in contact with the negative to be cleaned, the gear 53 is turned manually by the operator in a clockwise direction as viewed in FIG. 1 to simultaneously advance the wiping

cloths

24 and 25 from the

rolls

18 and 19 to the

rolls

21 and 22, thereby changing the sections of wiping

cloths

24 and 25, between the tubes 27 and 28.

The wiping cloth utilized in the apparatus 10 is a soft lintfree cloth especially designed for the accumulation of dust such as the soft polypropylene random woven cloth with long fibers of fine denier bonded together at the fiber crossover points by fusing or a resin binder which will not transfer from the cloth to a contacting surface. While this cloth provides an example of the type of cloth needed to provide adequate wiping of the negative surface and dust collection, it is contemplated that other forrns of cloth could be utilized where such cloth provides a dust-absorbing lint-free surface to wipe the negative.

Having thus described the invention with reference to preferred embodiment,

What is claimed is:

l. A cleaning apparatus for the removal of dust and other foreign objects from a sheet upon movement of a said sheet through said apparatus, said apparatus comprising:

a pair of hollow tubular support members having flexible semicylindrical walls positioned in opposed relationship to each other to define opposed parallel narrow support edges;

two lengths of soft, lint-free wiping cloth extending between said support members, the opposed surfaces of the sections of cloth between said narrow support edges defining part of a path through which a said sheet to be cleaned may be passed;

pressure means coupled with said support members for providing fluid under a predetermined constant pressure within said support members; and I support means for supporting the wall of each flexible support member in an area opposite said support edge to urge said sections of flexible cloth toward each other with essentially an equal pressure distribution along said support edges to afford intimate uniform pressure for cleaning between said sections of cloth and the surfaces of said sheet.

2. An apparatus according to claim 1 further comprising nuclear ionizing means for alpha particle emission mounted on said apparatus for ionizing air along said path to neutralize static electrical charges on a said sheet moved through said apparatus.

3. An apparatus according to claim 2 wherein said pressure means comprises:

a centrifugal blower; and

a duct attached between the outlet of said blower and said support members for directing air under pressure from said blower to said support members, said duct formed with an orifice positioned along said path for a said sheet to direct a stream of air across said path, and wherein said nuclear ionizing means is attached to the outlet of said blower for ionizing air pressurized by said blower so that said stream of air directed across said path will be ionized and will neutralize static electric charges on both surfaces of a said sheet moved through said apparatus after a said sheet has been cleaned by said apparatus.

4. An apparatus according to claim 3 wherein said nuclear alpha particle source comprises encapsulated polonium.

5. An apparatus according to claim 1 wherein said lint-free cloth is a random woven cloth comprising fine denier, nonlinting polypropylene fibers and means for bondirrg said fibers together to avoid the transfer of any material forming said cloth to a said sheet moved through said apparatus.

6. An apparatus according to claim 1 wherein said lint-free cloth is a random woven cloth comprising fine denier, nonlinting polypropylene fibers and a transfer-free bonding means for bonding said fibers together to avoid the transfer of said bonding means to a said sheet moved through said apparatus.

7. An apparatus for cleaning a sheet upon movement thereof along a path defined on said apparatus, which apparatus has cleaning means mounted along said path for removing dust and other foreign objects from both surfaces of a said sheet and ionizing means for ionizing air along said path to remove static electric charges from both surfaces of said sheet, wherein said ionizing means comprises a nuclear alpha particle source, and said cleaning means comprises a pair of adjacent flexible, resilient support members having opposed semicylindrical surfaces to define opposed narrow, parallel support edges defining a nip therebetween, which nip is disposed transverse to said path; two lengths of soft, lint-free wiping cloth extending through said nip, the opposed surfaces of the sections of cloth between said narrow support edges defining part of said path, said support members providing low even pressure to urge the opposed surfaces of said sections of cloth toward each other with essentially equal pressure distribution along said support edges when said edges and said lengths of cloth are moved away from each other at said nip by the passage of a said sheet therebetween; and means for advancing the lengths of cloth between said support edges.

UNITED STATES PATENT OFFICE I CERTIFICATE OF CORRECTION Patent No. 3, ,953 Dated Fe ruary 29, 1972 Im rentofls) Robert W. Christiansen it is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 18, after "therebetween" insert and Signed and sealed this 13th day of June 1972.

, (SEAL) Attest:

V EDWARDM-FLETCHERJR. ROBERT 'GOTTSGHALK Attesting Officer Commissioner of Patents -'ORM PO-IOSO (10-69) USCOMM-DC 60376-P69 UIS. GOVERNMENT PRINT NG OFFICE: 19" 0-366-334 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, m,953 Dated F ruary 29, 1972 Inventor(s) Robert W. Christiansen It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

(SEAL) Attest:

EDWARD M.FLETCIER,JR. ROBERT GO'ITSCHALK v Attasting Officer Commissioner of Patents FORM PO-IOSO (10-69) USCOMM-DC 6O376-P69 us. GOVERNMENT rnmnms ornce 1 I909 o-asa-ssa

Claims

1. A cleaning apparatus for the removal of dust and other foreign objects from a sheet upon movement of a said sheet through said apparatus, said apparatus comprising: a pair of hollow tubular support members having flexible semicylindrical walls positioned in opposed relationship to each other to define opposed parallel narrow support edges; two lengths of soft, lint-free wiping cloth extending between said support members, the opposed surfaces of the sections of cloth between said narrow support edges defining part of a path through which a said sheet to be cleaned may be passed; pressure means coupled with said support members for providing fluid under a predetermined constant pressure within said support members; and support means for supporting the wall of each flexible support member in an area opposite said support edge to urge said sections of flexible cloth toward each other with essentially an equal pressure distribution along said support edges to afford intimate uniform pressure for cleaning between said sections of cloth and the surfaces of said sheet.

3. An apparatus according to claim 2 wherein said pressure means comprises: a centrifugal blower; and a duct attached between the outlet of said blower and said support members for directing air under pressure from said blower to said support members, said duct formed with an orifice positioned along said path for a said sheet to direct a stream of air across said path, and wherein said nuclear ionizing means is attached to the outlet of said blower for ionizing air pressurized by said blower so that said stream of air directed across said path will be ionized and will neutralize static electric charges on both surfaces of a said sheet moved through said apparatus after a said sheet has been cleaned by said apparatus.

5. An apparatus according to claim 1 wherein said lint-free cloth is a random woven cloth comprising fine denier, nonlinting polypropylene fibers and means for bonding said fibers together to avoid the transfer of any material forming said cloth to a said sheet moved through said apparatus.