US1630724A - Apparatus and process for producing ophthalmic lenses - Google Patents

Description

1927. May 31, 5-D. TILLYER APPARATUS AND PROCESS FOR PRODUCING OPHTHALMIC LENSES Filed March 50, 1925 2 SheetsSheet l jwumdz 20 Edgar D. Finger.

y 1927- E. D. TILLYER APPARATUS AND PROCESS FOR PRODUCING OPHTHALMIC LENSES Filed March 30, 1925 2 Sheets-Sheet 2 inventor,

dgar D. 651 "Her.

Patented May, 31, 1927.

UNITED STATES PATENT OFFICE. I

EDGAR I). TILLYE R, OF SOUTHBRIDGE, MASSACHUSETTS, ASSIGNOE T AMERICAN OPTICAL COMPANY 0]? SOUTHBRIDGE, MASSACHUSETTS, A VOLUNTARY ASSOCIA- TION on MASSACHUSETTS.

Arrnne'ros AND rnocnss non rnonnome ornrnnmurc nnnsns.

Application filed March so, 1925. Serial no. 19,456.

This invention relates to" an improved apparatus and process for producin ophthalmic lenses, and has particular re erence 1 to the provision of a paratus and a process for producing multi ocal lenses from a single piece of lass.

' Prior to the invention there have been a number of methods used to produce multifocal lenses from .a single piece of glass, practically all of which methods embodied separate grinding and polishin 0 erations to produce the difl'erent focal li eld Such grindin and polishingoperations have been very di cult to perform and have'r uired 1 special and expensive machinery and s 'lled labor to operate the saine, all of which has resulted in the lenses being high in cost. Une of thedesirable characteristics of such lenses liesin the merging of the adjacent 2 focal'fields so'that the line of division between said fields would be substantially invisible. To produce the fields with such merging has been a diflicult manufactu 1 task, and a large percentage of blanks have had to be scrap ed because one surface has not merged with the other. i By my improved means I propose to roduce multifocal lenses with merged sur aces without having to resort to the diflicult 0' grinding and polishing operations as per formed in the prior art.

An important object of the present invention is to provide apparatus and an im proved process for producing "multifocal 5 lenses whereby an optical addition will be provided in a lens blank by moldin Another object is to provide suc apparatus and a process making use of pneumatic action in displacing a portion of a finished 0 optical surface.

Another object is to provide such apparatus and process utilizing a suction to producethe desired addition.

- Still another object is to provide such 5 a paratus and process whereby an optical addition may be fproduced upon a continuous finished sur ace without injuring the same.

Another object is to provide such appa- 0 ratus and process whereby the dioptric va ue of'the optlcal addition may be controlled at will by the amount of suction or the duration of its action. 7

Other objects and advantages will be place the block and the blank in apparent from the following description taken in connection with the accompanying drawings, wherein the apparatus and steps of the process are diagrammatically illustrated.

In the drawings,

throu h a lens blank and a supporting block therelbr as used in the improved process;

' Figure 2 is a vertical sectional view illusa lens blank to obtain the same result as that of Figure 2.

responding parts throughout the several views. v

In carryin out the invention I first provide a lens b ank 10 with a finished optical surface 11 upon one side thereof. The lens S 'lar reference characters designate corblank may be either plano in form, convex,

or concave, as is desired, and the finished surface 11 must correspondingly be prepared upon the surface to which'the optical addition is to be made. 11 then place the blank 10 upon a refractor supporting block-1'2 with the finished optlcal surface 11 exposed as clearly shown in Figure 1, whereupon I a suitable eating chamber or oven"13,'which is diagrammatically shown in Figure 2... This ,oven 13 preferably comprises sidewalls 14 and a top member 15 any of which may be ertured if desired to give ventilation. lectrical or other heating elements 16 are disposed within the chamber 13 and adapted to supply 'sufiicient heat to-render the lens blank 10 vsoft and substantially plastic.

'When the blank has thus been softened by I the action of heat, a suction cup 17 is brought into engagement with the finished optical surfaceill of the blank. his to be noted that the suction cup 17 is preferably circular in transverse section and provided with a sharp annular edge 18, which is e0 Figure 1 is a transverse sectional view adapted to contact with the surface 11 without injurg thereto. After the suction cup has thus can positioned, the pressure with- .in the same is reduced to a suflicient degree to draw up the covered portion of the surfacell, as clearly shown at 19, thus producing' a-curved surface of a different radius from the major surface 11. In this operation-the rear or bottom surface of the blank is also drawn up, as shown at 20, forming a rather irregular depression, whichmust afterwards be ground away.

In order to facilitate ready manipulation and tomake it adaptable to different curvatures of lens blanks, the suction cup 17 is mounted upon a sleeve 21 which is slidable Within a ball socket 22 pivotally mounted in the cover of the heating chamber- Ofcou'rse, there are a great many different materials which may be employed in the suction on 17 but one of the principal requirements is. that it shall be able to Withstand the action of heat, and. furthermore that the glass will not have a tendency to adhere that the operation may be performed upon either side of a lens its shape.

After the blank 10 on the supporting block 12 is placed in the heating chamber 13, the temperature is gradually increased until blank regardless V of it reaches approximately 1000 to 1400 de? grees Fahrenheit, under which temperature the glass it becomes sufliciently softened for this operation, whereupon thecup 17 is applied and a portionof the lens thereb actuated by suction. It is to be noted t at the dloptric value of the optical addition 19 may be controlled at will by the amount of the suction or the duration of its, action upon the'glass, so that in this way multifocal lenses of an desired addition may be conveniently pro uced. 7

After the previously finished surface is thus formed, the blank is removed from the heatin chamber and the bottom side 24 1s eventua ly ground off to remove the depression and to produce a finished opti cal surface 25 on the reverse side of the blank; thus a complete lens is formed which may be cut to any size, for exam Is as illustrated by dot and dash line 26 in Figure 4, and thereafter applied to a spectacle or eyeglass mounting.

In carrying out the invention I do not limit myself to the use of a suction for displacing a portion of the finished surface of the lens blank, since any other method of pneumatic pressure variation upon the different portions of the surface may be employed.

For example, as illustrated in Figure 6, a lens blank 27 supported by a refractory block 28 is positioned within a heating chamber 29, wherein it may be softened by means 'of the usual heating elements. In this form of the invention a tube 30 is slidably mounted within a ball and socket joint 31, saidtubehaving its loweror inner end tapered to a knife edge as at 32 for contact with the finished surface of the lens blank. The upper or outer end of the tube 30 is open to the atmosphere as at 33, instead of being connected to a suction pump as in the previous embodiment. The heating chamber 29 is completely enclosed by the walls of the oven 34 and at the proper time is supplied with fluid or pneumatic pressure through a pipe 35 extending from any suitable source of supply.

With this form of the invention after the blank 27 has been suitably softened and the tube 30 "applied to its surface, as clearly shown, compressed air or other suitable medium is supplied through the pipe 35 to the chamber 29 so'as to apply a ressure to that portion of the finished sur ace of the blank which surrounds the extremity 32 of the tube 30. Since this pneumatic pressure is greater than that of the atmosphere within the tube 30, that portion of the blank covered by the end of the tube will be displaced as at 36 because refractory blocks such as fire brick and carborundum which are commonly used for supporting plastic lenses are porous and the increased premure in the chamber 29 will exert a pressure up through the porous block 28 and cause the plastic glass to bedisplaced upwardly into the tube 33, the extent of said dis lacement being controllable at the will of t e o erator by regulating the pressure in the 0 amber 29.

From the fore oing it will be evident that I have rovide a process which is es eciall a a table ;for production of In tifoca opht almic lenses, and which will be simple to apply in practice and economical to carry out. By virtue of the fact that no material touches the finished surface 11 while the blank is in the softened condition, there will be no necessity for afterwards either grinding or polishing the multifocal surface. Obviously changes may be resorted to in the details and arrangement of the steps of the process, and the right is herein reserved to make such chan es as fall within the scope of the append claims without departing from the spirit of the invention.

Having thus described my invention, I claim:

'1. The process of producing multifocal lenses comprising finishing a piece of glass to a polished lens surface, heating the glass to plasticity and drawing up a portion of the polished surface to a difierent curvature by suction applied to the polished surface without the said displaced polished surface coming in contact with anything to shape it.

2. The process of producing multifocal lenses comprising finishing'a piece of glass to a polished lens surface, heating the glass to plasticity and pneumatically displacing a portion of the polished surface to a different curvature without the said displaced polished surface coming into contact with anything to shape it,

3. The process of making multifocal lenses comprising finishing a piece of glass to a polished lens surface, heating the glass to plasticity, and displacing a portion'of the polished surface to a different curvature by varying the atmospheric air pressure on the lens whereby a portion of the polished surface is displaced to a different curvature without said displaced surface coming in contact With anything to shape it.

4 In a device of the character described,

a block for supporting a heated lens, a tube attached to the tube, 11

change the atmospheric pressure on the lens 40 the oven, a tube having an annular edge,

adapted to contact with the outer face of the lens a pneumatic coupling attached to the tube adapted to change the atmospheric pressure on that portion of the lens within the annular edge'of the tube and means for mountingthe tube whereby it may be moved to desired position on the lens.

8. The process of making a multifocal lens comprising polishing a piece ofglass to a polished lens surface, heating the glass to plasticity, resting an annular compress on the polished surface, and changing the air pressure on the glass to force a portion of the polished surface up into the compress without touching anything.

9. In a device of the character. described, a block for supporting a heated lens, a tube having an annular edge resting on theouter surface of the lens, and means for changing the atmospheric pressure on the lens to force a portion of the outer surface up into the tube without said displaced surface contacting with anything.

EDGAR n. TILLYER.

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