US2846974A - Cathode-ray tube filming apparatus - Google Patents

Description

Filed July 26, 1957 P. J. KINscl-l cA'rHoDE-RAY TUBE FILMING APPARATUS 2 Sheets-Sheet 1 Aug. 12, 1958 F. J. KlNscl-x CATHODE-RAY TUBE FILMING APPARATUS 2 sheets-sheet 2 Filed July 26, 1957 United States Patent Y(il) cArHoDE-RAY TUBE FILMING APPARATUS Francis J. Kinsch, Chicago, lll., assignor to The Rauland Corporation, a corporation of Illinois Application July 26, 1957, Serial No. 674,333

1 Claim. (Cl. 118-317) This invention relates in general to cathode-ray tubes and 1n particular to apparatus for applying an organic iilm to the exposed luminescent screened faceplate of Acathode-ray tubes.

Preparatory to the aluminizing process in the manufacture of aluminized cathode-ray tubes, a lacquer lm is applied to the prepared luminescent screen affixed to the inside surface of the envelope faceplate. This lacquer film serves as a foundation upon which aluminum vapor can be deposited and must be so applied as to form a uniform and taut base if the subsequently deposited aluminum is to provide a mirror-like backing for the luminescent screen.

A conventional lacquer filming method is based on a liotation process which utilizes a water column upon vwhich lacquer is deposited. Subsequent decantation of the water permits the lacquer iilm to adhere to the luminescent screen. An obvious shortcoming of this process is the time consuming element. Another known lacquer filming process involves the use of stationary spraying apparatus in conjunction with a mechanism which rotates the cathode-ray tube envelope while the lacquer is sprayed on to its luminescent surface. In practicing this method, rotating the envelope is necessary in order to distribute the lacquer uniformly over the luminescent screen. This spinning requirement raises difiiculties in the adaptation of such a method to automation activities since the individual cathode-ray tube envelopes must be positioned vupon the spinning mechanism or otherwise disassociated from the conveyor which transports "the envelopes during the manufacturing process prior to the lacquer spraying operation.

In accordance with the invention,l therefore, it is a A primary object to provide a novel apparatus for discharging an organic film onto the luminescent screened surface of a cathode-ray tube envelope.

It is also an object of this invention to provide a novel lacquer filming nozzle arrangement which renders unnecessary any manipulation of the cathode-ray tube envelope during the filming operation.

In accordance with the invention, apparatus for applying an organic film to the luminescent screened surface of a cathode-ray tube envelope includes means for supporting the envelope in a fixed position with its axis substantially vertically oriented and with the faceplate uppermost. A coaxial conveyor comprises film solution conveying means and includes a pair of coaxially disposed conduits which extend vertically into the envelope below. A reservoir containing a liquid supply of organic lacquer material under pressure is coupled to the inner one of the coaxial conduits while the supply of compressed gas is coupled to the outer conduit. A nozzle fixed to the upper extremity of the outer conduit communicates with both conduits and includes an olset portion having its upper extremity terminated Eby an asymmetrical discharge orifice. Further, means are provided for rotating the reservoir and the nozzle-supporting coaxial conveyor and for producing a rotating spray of 2 atomized organic film solution within the envelope and directed toward the luminescent screen.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claim. The organization and manner of operation of the invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings, in the several figures of which like reference numerals identify like elements, an in which:

Figure l is a side elevation view, partly in section, of a film spraying apparatus which embodies the subject invention;

Figure 2 is a fragmentary cross-sectional view taken along the line 2-2 of Figure 1;

Figure 3 is a fragmentary view, partly in sectiontaken along the line 3-3 of Figure 1;

Figure 4 is a sectional view of the inventive nozzle arrangement utilized in the apparatus shown in Figure l;

Figure 4a is a cross-sectional View taken along the line 4a-4a of Figure 4;

Figure 5 is an end view of the nozzle arrangement taken along the line 55 of Figure 4;

Figure 6 is an oblique view of the nozzle arrangement taken along the line 6 6 of Figure 4; and

Figure 7 is a top View of the cathode-ray tube envelope depicted in Figure 1.

The apparatus of Figure l includes a table 10 which supports a drive motor 11 that is coupled through a gear box 12 to a shaft 13 which is journalled within the bearing 14 and fixed to a driving pulley 15. Pulley 15 is coupled to a centrally located driven pulley 16 through a drive belt 17. Driven pulley 16 supports the idler bearings 18, more clearly shown in Figure 2, which are positionably mounted thereto by conventional threaded bolt fasteners 19 in conjunction with spacers 20. A multiapertured plate 21 receives fasteners 19 and in cooperation with driven pulley 16 aligns idler bearings 18. Bearings 18 communicate with the race surface 22 of a collar 23 which is secured by screw fasteners 24 to the surface of table 10.

Depending from driven pulley 16 are a plurality of spaced internally threaded couplers 25 secured to pulley 16 by nut fasteners 26. Attached to couplers 25 are a pair of support arms 27 (only one shown in Figure l), and an elongated support and driving arm 28. Support arms 27 and driving arms 28 are fastened to the inner periphery of a ring-shaped reservoir 29 which has a sump 30, a feed pipe 149, a filler neck 31, and a cap 32. The lower extremity of arm 28 sustains a circular member 33, better shown in Figure 3, whichis engageable with a bifurcated driven lug 34. An insulator 35 carried by lug 34 has a pair of slip rings 36 which communicate with a pair4 of resiliently mounted contacts 37 that can be energized via the electric power cable 38 from a source of electric energy (not shown). Slip rings 36 are electrically connected by a conductor pair 39 to a solenoid 40 which is operably coupled to an actuating crank 136 associated with a spray gun 51 which can be of a conventional type.

Driven member 34 is releasably secured by a conventional threaded member 42 to a support member 41 which has an axial bore 137. A sleeve bushing 43 provides bearing support for driven lug 34 and further provides for journalled engagement with a collar 44 which is secured to the channel brace 45 fixed to table 10. Pressurized air is coupled through a conventional rotating air seal-46 to a flanged inlet member 47 secured to support member 41. Member 47 communicates with a T-connector 48 through axial bore 137. T-connector 48 is coupled to an air pressure regulator 49 and to the control valve 112 associated with solenoid 40. Tubing 50 connects pressure regulator 49 through a T-coupler 138 to reservoir 29 and to an air pressure chamber (not shown) of spray gun 51 while tube 52 pipes a filming lacquer 53, which can be isobutyl methacrylate, to a A fluid chamber (likewise not shown) of gun 51.

a wing nut 59, in conjunction with clamp 56 rigidly secures extension 54. A second wing nut 60 anchors clamp 56 to plate 2l.

The uprights 61, fastened to surface 150 of table 18, mount an apertured guide plate 62 which in turn carries the demountable uprights 63. Uprights 63 are terminated by a ring 64 which supports and vertically orients a cathode-ray tube envelope 65 having a prepared luminescent screened surface 66.

Vertically positionable upon supports 6l is a drain pan 67, which includes a deliector pad 68, centrally disposed about extension 54. Pan 67 is positionably secured by conventional fasteners 69. A water supply inlet 140 (source not shown) is terminated by a control valve 70 and provides a constant wash for pan 67. An outlet tubing 71 is connected to drain pan 67.

Figure 4 shows the upper portion of extension 54 and nozzle 55 in longitudinal section. Coaxial extension 54 comprises an outer conduit 727 an inner conduit 73, and a needle valve 74 which elements can cooperate with spray gun 51 in a conventional manner. Conduits 72and 73 are coupled to the above-mentioned air and fluid chambers, respectively, of spray gun l while needle valve 74 is operably associated with the actuating crank 136 of gun 51. An aligning shoulder 75 terminates the upper end of inner conduit 73 and is in Contact with the inner surface of con-duit 72 thereby attributing a measure of rigidity to coaxial extension 54. Shoulder 75 is provided with longitudinal openings 76 (better shown in Figure 4a) which communicate between an annulus 77 and the included space between conduits 72 and '73. An insert 78 has a threaded portion 79 at its lower extremity for attachment to a correspondingly threaded inner surface of rconduit 73. Insert 78 maintains a conical portion Si) at its upper extremity and includes a tapered channel 81 for communicating at its upper end with the central bore 82 in nozzle 55 and at its opposite end with conduit 73. The base 83 of nozzle 55 is seated upon a gasket 84 and is demountably secured within the crown 85 which terminates outer con-duit 72 by a collar 86. The conical portion 8@ of insert 78 in conjunction with the inner surface of nozzle base 83 defines a passage 87 between annulus 77 and bore 82. In accordance with the invention, nozzle 55 is provided with an offset portion 88 incorporating an asymmetrical discharge orifice comprising a pair of oblique walls 89 (detailed in Figures 5 and 6) which terminate bore 82 of nozzle 55. Other features of the associated apparatus described above are described and claimed in the copending application of Nathan D. Levin for Cathode-Ray Tube Manufacturing Method and Apparatus, filed concurrently herewith and assigned to the present assignee.

In operation, the subject invention contemplates the application of a lacquer film to the luminescent screened surface 66 of a cathode-ray tube envelope 65, `by `directing a rotating spray of an air-lacquer mixture thereupon. With reference to the above described embodiment, it is apparent that upon energization of motor 11, rotational energy is translated through gear box 12, shaft 13, and driver pulley to propel driven pulley 16 via belt 17. Idler bearings 18 which support pulley 16 and plate 21, being confined within race 22 of collar 23, enable the spray filming apparatus to be rotatably impelled at a controlled velocity. Pressurized air is admitted through rotating seal 46, inlet member 47 and axial bore 137 to regulator 49 and control valve 112. Regulated air pressure is thus available through tube 50 and T- coupler 148 to reservoir 29 thereby urging lacquer through feed pipe 149 and tube 52 to the fiuid chamber of gun 5l. Regulated air pressure is simultaneously available to the :air chamber of gun 51. It is noted at this juncture that the constituents for spray filming, i. e., a supply of filming lacquer 53 and a source of regulated air pressure, are available to the rotating apparatus without employing a rotating lacquer seal.

Accordingly, while the apparatus is rotating, as above described, a spray filming operation is commenced by electrically energizing solenoid 4f) from an electrical source (not shown) coupled to solenoid 4i) via cable 38, resilient contacts 37, rings 36 and cable 39. The energization of solenoid 49 operates valve 112 permitting unregula-ted pressurized air to actuate crank 136 of spray gun 51. The actuation of crank 136 simultaneously couples the aforementioned liquid and air chambers of gun 51 to conduits 73, '72, respectively. The internal operation of gun 5l which performs this operation is conventional and well known in the spray gun art and therefore is not detailed here. A conventional presettable mechanical adjustment on gun 5l (not shown) controls the vertical positioning of needle valve 74 within tapered channel 81 thereby determining the lacquer ow rate from conduit 73 through channel 8i to bore 82,

With reference to Figure 4, it is noted that upon admission to conduit 72, pressurized air passes through openings 76, annulus 77 and passage 87 to confront pressurized lacquer at the entrance to bore 82 in nozzle 55. The juncture of passage 87 and channel S1 comprise, in effect, a volatilization chamber or atomizer which produces a turbulent mixture of air and lacquer for introduction to bore 82. Offset 88 directs the aforesaid mixture obliquely with respect to the axis of tube 65. The oblique walls 89 which terminate bore 82 comprise an asymmetrical orifice which transforms the air-lacquer mixture into the diverging mist 200, shown in elevation in Figure l and in plan in Figure 7. The configuration and density of mist 200 insures a uniform deposit of lacquer film on surface 66 by directing a comparatively heavy stream of air-lacquer mist outwardly towards the periphery of tube 65 while providing a progressively decreasing mist density as the axis of tube 65 is approached. Offset 88 further provides that the upward discharge of mist 200 perceptibly overlaps the vgeometric center of the tube in order to obviate a blank or non-uniform film layer on that area. The deflector pad 68 protects gun 51 and its associated apparatus by diverting excess lacquer to the adjustable drain pan 67 which is provided with a water circulatory system and continually drains to carry oflt such excess.

Upon the completion of the spraying operation, de-energization of solenoid 40 returns crank 136 to its initial position thereby closing the air and liquid chambers of gun 51. It would be but a matter of simple expediency to utilize a conventional timing mechanism to initiate, time, and terminate the abovementioned spray filming operations in a predetermined sequence in conjunction with drive motor 12 operation to apply lacquer film layers having a high degree of uniformity to cathode-ray tube envelopes.

In summary, spray filming apparatus depicted in Figure l avoids the limitations of the prior art by incoporating coaxial air and lacquer conduits which are adaptable to rotatable operation without the requirement of a rotating lacquer seal, thereby obviating the necessity of coping with the inherently disagreeable qualities of lacquer material generally encountered under such conditions. The described embodiment provides a compact unitary arrangement which employs a conventional spray gun 51 in conjunction with a simplified mechanical coupling and driving arrangement. Furthermore in view of the fact that nozzle 55 (as Well as uprights 63) admits of facile interchangeability, the application of this novel apparatus to a variety of spray filming operations is enhanced. Pro vision of an offset nozzle with an asymmetrical discharge orice, in accordance with the present invention, permits spraying over a screen area subtended by an angle in excess of ninety degrees and has been found to provide a spray of much greater uniformity throughout the screen area than conventional straight nozzles with symmetrical discharge oriiices.

While a particular embodiment of the invention has been shown and described, it will be obvious to those skilled in the art that changes and modications may be made without departing from the invention in its broader aspects, and, therefore, the aim in the appended claim is to cover all such changes and modifications as fall Within the true spirit and scope of the invention.

I claim:

Apparatus for applying an organic lm to the exposed surface of aluminescent screen aixed to the faceplate of a cathode-ray tube envelope comprising: means for supporting said envelope in a fixed position with its axis substantially vertically oriented and said faceplate uppermost; solution conveying means comprising a pair of coaxially disposed conduits extending vertically into said envelope from below; a reservoir containing a liquid supply of organic lacquer material under pressure and coupled to the inner one of said conduits; a supply of compressed gas coupled to the outer one of said conduits; a nozzle, comprising an offset portion terminated at the upper extremity thereof by an asymmetrical discharge orice, fixed to the upper extremity of said outer conduit .and communicating with both said conduits; and means, including means for rotating said reservoir and said conveying means, for producing a rotating spray of atomized organic film solution Within said envelope and directed towards said luminescent screen.

No references cited.

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