Plastic lens

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Drawing sheet — no readable text.

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Patented Oct. 17, 1950 2,525,921

UNITED STATES PATENT OFFICE

PLASTC LENS

Edward K. Madan and Robert W. Madan, Maple wood, N. J., assignors to The Emeloid Co. In corporated, Arlington, N. J., a corporation of

New Jersey

Application November 19, 1947, Serial No. 786,930

This invention relates to lens and more parti first described in connection. With the accom cularly to a magnifying lens for use in connection panying drawings, showing a plastic lens of a with television receiving sets to magnify the preferred form embodying the invention, and the image produced on the tube, or for magnifying features forming the invention will be specifically the images produced by any form of cathode ray 5 pointed out in the claim.S.

or similar tube.

The image producing tubes, or cathode ray Figure 1 is a perspective view of the improved tubes of television sets and other similar uses lens.

are very expensive, and their cost increases ma Figure 2 is a section through the lens taken. On terially with an increase in size, and the Size of O the line 2-2 of Figure 1.

the produced image is dependent upon the size Figure 3 is a section through the lens taken on of the tube, also the cost of the companion equip the line 3-3 of Figure 1.

ment increases with the increase of the size of Figure 4 is a section through a modified form of the image producing tube with the result that a the lens.

television set which Will produce an image Or Referring more particularly to the drawings, picture of practical easily viewed size is of a pro the improved lens as shown in Figures 1 to 3 hibitive cost for the average householder. of the drawings comprises the front piece and The cost of ground crystal magnifying lens of the back plate or back piece 2. The front piece suitable size to magnify the images produced by may be pressed, molded or otherwise formed of a television set employing a practical size tube, 20 a thermoplastic such as thermoplastic methyl from a cost standpoint, to a practical, easily methacrylate resin or other similar thermoplas viewed size is also comparatively high so that tic which is very clear, that is, has a high degree little could be gained in cost reduction of tele of clarity and which has dimensional stability so vision sets by employment of a ground Crystal that it may be held true to the shape assumed lens with a small size tube. in the forming of the piece. The front piece An object of the present invention is to pro has a convex outer surface 3 and it is shaped vide a lens suitable and particularly adaptable to provide a concave inner Surface which when for use in a television set, or in connection with the back plate 2 is attached to the front piece any form of cathode ray or similar tube, which will form a hollow space 4. The front piece 3 lens will magnify the images produced by the () is shown as provided with an annular flange 5 tube to a desired size and which lens may be completely surrounding it. The back plate 2 manufactured for only a fraction of the cost of may be pressed, molded or otherwise suitably a ground crystal lens. formed of clear dimensional stable thermoplastic More specifically, the present invention com of the same type and nature of the thermoplastic prehends the production of a lens made of ther 5 of which the front piece is formed. This plate noplastic such as thermoplastic methyl meth 2, which is fat, is cemented, thermally bonded acrylate resin, or other similar thermoplastic of or otherwise attached to the flange 5 of the front high clarity, and dimensional stability, which is piece So as to form an air and fluid tight joint weather resistant, has low moisture absorbtion 40 between the front piece and back plate 2. In and is shatter resistant. (Two Such thermoplas the form shown in Figures 1 to 3 of the drawings tics are Lucite and Polystyrene, both commercial the back plate 2 has an enlarged boSS or enlarged products now on the market.) The lens is portion 6 formed thereon which is provided with molded in one piece, molded or pressed in two a filling passage 7. The filling passage 7 opens pieces or otherwise suitably produced to provide out through the outer edge of the boss 6 and into a hollow body lens having a convex front and flat the hollow space 4 between the front piece and back or a convex front and a convex back. The the rear plate 2 so that the space 4 may be filled space between the front and back or the hollow with a liquid. The liquid with which the space in the body is filled with a liquid, preferably a 4 is filled may be of any liquid which has the mineral oil which has the same refractive index same or very close to the same refractive index as the refractive index of the thermoplastic of as the refractive index of the plastic of which the which the lens body is formed. front piece and back plate 2 are formed. A With these and other objects in view, as may clear, transparent mineral oil is preferable for appear from the accompanying specification, the use as the filling liquid. After the hollow space invention consists of various features of con 4 is filled with the liquid the filling opening or struction and combination of parts, which will be 5 passage 7 is closed by a closure plug 8 which may

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be cemented into the Opening, threaded therein being of such size that when closed by said or otherwise suitably attached so as to form a closure plug a pocket is left which communicates tight closure for the passage 7. As clearly shown with the hollow of the body, the hollow of said in Figure 3 of the drawings, the plug 8 is much body being filled with a liquid having approxi smaller or shorter than the passage 7 so that a 5 mately the same refractive index as the refrac major portion of this passage 7 will be left un tive index of the thermoplastic body. filled to form an expansion pocket or space to 3. As a new article of manufacture, a magni a CConnodate any expansion of the liquid with fying lens for magnifying the images produced Which the space 4 is filled under heat variances by cathode ray or similar tubes, comprising a to Which it may be subjected. front piece having a convex outer face and a con Figure 4 of the drawings shows a slightly modi cave inner face and made of a thermoplastic fied construction of the lens, and in this form of high clarity and dimensional stability, a both the front piece l' and the back plate 2' back plate made of a thermoplastic of high have convex outer Surfaces. Otherwise the con clarity and dimensional stability, said front Struction of the modified form of the lens is the l8 piece and back plate having contacting bonded same as that shown in Figures 1 to 3 of the draw engaging connection around their edges to pro ings. That is, the front and back pieces f' and vide an air and liquid tight hollow body, said 2' are cemented together around their edges and hollow body filled with a liquid having approxi provide the hollow space between them which is mately the same refractive index as the re filled with the liquid having the same or approxi- 20 fractive index of the thermoplastic body, said mately the same refractive index as the plastic front piece having an offset filling opening from which the front and rear pieces are made formed on the outer surface thereof, a closure or formed. plug in Said filling opening, said filling opening in The front piece and back plate or back piece of the assembled structure to communicate with the lens may be formed by thermal pressure 25 the hollow of the body and form an air and ex forming means from sheet stock, may be molded pansion chamber open to the hollow of the body. in dies with the usual method of thermal molding 4. As a new article of manufacture, a magni of plastics of this type or either one of them may fying lens for magnifying the images produced be molded and used with a pressed or formed by cathode ray or similar tubes, comprising a other element without departing from the spirit : front piece having a convex outer face and a of the present invention. concave inner face and made of a thermoplastic It will be understood that the invention is not of high clarity and dimensional stability, a back to be limited to the specific construction or air plate made of a thermo-plastic of high clarity rangement of parts shown, but that they may and dimensional stability, said front piece and be widely modified within the invention defined 35 back plate having contacting bonded engaging by the claims. connection around their edges to provide an air What is claimed is: and liquid tight hollow body, said hollow body 1. As a new article of manufacture, a magni filled with a liquid having approximately the same fying lens for magnifying the images produced refractive index as the refractive index of the by cathode ray or Similar tubes, comprising a 40 thermoplastic body, said back plate having an offset filling opening on the outer surface thereof hollow body of a thermoplastic of high clarity and extending into said hollow body, a closure and dimensional stability, said hollow body filled plug with a liquid of approximately the same refrac in Said filling opening, said filling opening tive index as the refractive index of the thermo in the aSSembled structure to communicate with plastic body, said body provided with an offset 45 the hollow of the body and form an air or ex filling opening formed on the outer surface of pansion chamber Open to the hollow. the body and extending into the hollow portion EDWARD. K. MADAN. thereof, a closure plug in said filling opening, ROBERT W. MADAN. Said filling opening being of such size that when closed by said closure plug a pocket is left which REFERENCES CITED communicates with the hollow of the body and The following references are of record in the forms an air or expansion chamber open to the file of this patent:

hollow. UNITED STATES PATENTS 2. As a new article of manufacture, a magni fying lens for magnifying the images produced 55 Number Nae Date by Cathode ray or similar tubes, comprising a 57,602 Warden ------------ Aug. 28, 1866 front piece having a convex outer face and a 60.109 Woodward -------- Nov. 27, 1866 concave inner face and made of a thermoplastic 1,569,973 Goettert ---------- Jan. 19, 1926 of high clarity and dimensional stability, a back plate made of a thermoplastic of high clarity 5-1333 and dimensional stability, said front piece and connection around their edges to provide an air and liquid tight hollow body, said frontpiece element of said hollow body provided with an off- 65

Set filling opening formed on the outer surface thereof and extending into said hollow, a closure plug in Said filling opening, said filling opening

back plate having contacting bonded engaging 15255803 Nicol

Number

FOREIGN PATENTS