US2767684A - Apparatus for forming juxtaposed coatings - Google Patents

Description

Oct. 23, 1956 P. K. WEIMER ETAL APPARATUS FOR FORMING JUXTAPOSED COATINGS 3 Sheets-Sheet 1 Filed March 25, 1953 INVENTORJ 541/4 K. WE/Mf/B mm 4 A/ae C. THOMPSON QQZJM JTTORNEY I 23, 1956 P. K.IWEIMER EFI'AL 2,767,684

APPARATUS FOR FORMING JUXTAPOSED COATINGS v Filed March 25, 1953 3 Sheets-Sheet 2 PA 11 A. wmf efiiifi HARE) C THOMPSON ll TTORNE 1 Oct. 23, 1956 P. K. WEIMER ErA L APPARATUS \FOR FORMING JUXTAPOSED commas s sheets-sheet 5 Filed March .25, 1953 INVENTORJ PAUL K. WE/M519, HARRY THOMPSON v .TTORNEY APPARATUS FOR FORMING JUXTAPOSED COATINGS Paul K. Weimer and Harry 'C. Thompson, Princeton, N. .L, assignors to Radio Corporation of America, a corporation of Delaware Application March 25; 1953, Serial No. 344,499

10 Claims. (Cl. 118-503) This invention relates to apparatus for making fine juxtaposed lines or strips as well as superimposed layers of difierent materials particularly useful .in making ray sensitive targets for cathode ray color television'tubes. More particularly this invention relates to apparatus for forming juxtaposed layers of a given width and superimposed layers of a ditferent width such as may form the color filter strips and signal strips of a target especially useful in a simultaneous color television pickup tube.

In the application of P. K. Weimer, Serial No. 344,498, now Patent Number 2,745,773 filed simultaneously herewith and assigned to the assignee of this application there is shown and described apparatus for forming a plurality of juxtaposed color filter strips on a light permeable workpiece; each of the color filter strips being composed of a plurality of superimposed layers. A plurality of spaced signal strips are positioned one on each of the color filter strips. The problems of forming such strips or layers will be more readily appreciated when it .is understood that they are extremely narrow in width ranging around a few mils or less. Such strips and layers are required to be accurately located or registered with respect to each other; with the permissible tolerance being a few 10,000ths of an inch or less. When superimposed layers are formed of different width it is necessary that the mask having elements, such as a wire masking grill, defining the width of the apertures and thereby the width of the strips or layers formed, be changed to one having the same number of elements or wires but of diiferent thickness or diameter to secure the change in width of successive coatings. While it may be possible to form such matching sets of masking grills with that degree of precision required here, we have found that the necessity for doing so may be avoided.

It is therefore a principle object of our invention to provide an improved apparatus for readily making fine juxtaposed coatings on a workpiece with a high degree of precision.

Another object is to provide improved apparatus for readily making fine juxtaposed strips and strips superimposed thereon capable of a high degree of precision in operation.

Another object is to provide apparatus for readily making fine juxtaposed coatings on a workpiece in which the elements forming the apertures in a mask are accurately closely spaced from the workpiece.

Yet another object is to provide an apparatus for forming juxtaposed strips of a given width and superimposed thereon strips of a different width and at the same time insuring great accuracy.

A further object is to provide an apparatus for making extremely fine and accurately located juxtaposed strips and strips superimposed thereon wherein the width of the superimposed layers may be readily varied and at the same time readily accurately registered in a predetermined location.

In accordance with our invention we provide precision States Patent holder 19 movably mounted there-in.

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spacing means adjustably mounted on a framework which carries a workpiece holder. The framework is removably mounted on a base which supports the masks forming the apertures through which material is evaporated onto the workpiece. One of the masks is made up of a plurality of fine closely spaced wires. The precision locating means are so positioned on the framework that they engage the individual wires of the wire masking grill and automatically space them with respect to each other as well as the workpiece. Thus, in forming successive superimposed layers on the workpiece, the framework supporting the workpiece may readily be disconnected from the base and removed therefrom. When the framework is once again connected to the base registration of given portions of the workpiece with the same apertures of the wire masking grill is readily accomplished; registration being virtually automatically accomplished when the precision locating means engages the wires of the masking grill. The holder may be mounted so as to be readily displaced in a given direction to expose different portions of the workpiece to the apertures of the wire masking grill. A movable mask may be mounted on the base having apertures which determine the effective length of the apertures formed by the wire masking grill. A controlled atmosphere may be provided in a chamber in which the apparatus is mounted and the various movements of the workpiece and movable mask are effected by controls mounted externally of the chamber; thus facilitating the successive formation of coating or strips on difierent portions of the workpiece.

Further objects as well as advantages of our invention will be apparent from the following description and the accompanying drawing in which Figure l is an elevational view, partly in section, of apparatus constructed in accordance with our invention;

Figure 2 is a perspective view partially broken away for convenience of illustration of a jig constructed in accordance with our invention;

Figure 3 is a sectional view taken along the line 33 of Figure 2;

Figure 4 is a sectional view taken along the line 4-4 of Figure 2; and

Figure 5 .is a fragmentary view on an enlarged scale of a portion of the apparatus shown in Figure 4.

Referring now to the drawing in detail it is seen that the apparatus includes a jig 10 supported in a bell 11 above an evaporator 12; the interior of hell 11, in the present instance, being connected to a vacuum pump (not shown). Such an apparatus is described in detail in the P. K. Weimer patent referred to hereinabove. Only so much thereof as is deemed necessary to a proper understanding of our present invention will be repeated here.

Jig 10 is supported on a platform 13 having an opening 14 formed therethrough. Jig 10 comprises two major subassemblies which are readily disconnected and connected again .in accurately alined relation. The base or mask subassembly includes a fixed mask 15 having elements defining a plurality of apertures therebetween mounted on a base 17. A movably mounted mask 16 is also mounted on base 17. The workpiece subassembly includes a supporting framework 18 having workpiece rately locating workpiece holder 19 with respect to masks 15 and 16 are provided.

On the upwardly presented surface of the base 17, a pair of oppositely disposed guide rails 20, 21 form a guideway in which movable mask 16 is slideably mounted.

Movable mask 16 is advantageously provided when it is desired to either limit the portion of the workpiece exposed to the apertures of fixed mask 15 or to oifset successively formed strips. Means for positioning movable mask 16 with a high degree of accuracy are pro- Means for accuvidcd by means of which both a large and fine adjustment of movable mask 16 may be readily made. Movable mask 16 may be selectively positioned in the guideway on base 17 by rotatably mounted arm 22, a finger portion 22' of which engages movable mask 16. Arm 22 is supported on and rotatable with. rod 23. In the present instance a separate fine adjustment of movable mask 16 is effected by means of rod 24 rotatably mounted in base 17. Stops in the form of collars 25, 26 are mounted in spaced relation on rod 24 and are engaged by a downwardly projecting portion of movable mask 16.

Mounted on base 17 and positioned over movable mask 16 is the fixed mask 15. One advantageous form of fixed mask is a wire masking grill having a plurality of fine closely spaced wires roughly indicated at 27 and supported by two spaced cylinders 28, 29 which. may be threaded to receive the .wire. The wire utilized may be of any suitable material. However, wire which may be stretched under tension such as Wire formed of an alloy of 85% nickel and 15% chromium is particularly suitable. The wire is wound and then fixed on cylinders 28, 29 in any convenient manner such as is well known in the grid making art; unwanted portions of the wires being cut away. Cylinders 28, 29 and, with wires 27 connected therebetween, are each mounted on a frame 30 as by bolts 31 in such manner that wires 27 may be tensioned andstretched. This serves to remove kinks or bends remaining in the wires after their attachment to the. cylinders.

As indicated above, workpiece holder 19 is mounted in framework 18. An aperture is. provided in holder 19 in which workpiece 32 is removably seated. Resilient finger 33 together with spring loaded plungers (not shown) firmly maintain workpiece 32 in position. Holder 19 is mounted in a guideway formed in framework 18 and is slidcable in the direction indicated by arrow 34. A spring loaded plunger (not shown) is mounted in framework 18 so as to bear against one end of the holder 19 and urge the opposite end thereof against one end of micrometer screw 35. Micrometer screw 35 i is in threaded engagement with framework 18 by means of a precision thread which permits fine adjustment of the position of the workpiece holder. Rotatably mounted rod 36 is connected to micrometer screw 35 through a suitable gear train. Graduated scales shown in Figure .2 are mounted on micrometer screw 35 and framework 18.

As described in detail in the above identified patent, set screws 50 opposed by spring loaded plungers (not shown) may be mounted in framework 18 so as to permit the adjustment of the position of the workpiece holder 19 in its guideway.

Means for securing accurate spaced relationship between workpiece 32, supported in holder 19 with respect to the wires of fixed mask 15, as well as between the wires themselves are provided and include members having matching grooves or slots accurately formed there in to receive the elements of fixed mask 15. Such members may advantageously be in the form of cylinders 38 and 39 with each threaded on its surface in an extremely precise manner so as to form a precision thread with the threads on the cylinders matching one another. Methods of forming such precision grooves or threads of extreme accuracy are known in the metal working art and need not be described in detail here. The threads are formed with the same number of turns per inch as there are elements per inch in wire masking grill 15. Cylinders 38, 39 are each removably mounted in a yoke 40 which in turn is adjustably connected to and supported by framework 18. Two setscrews 41 are each threaded into framework 18 and bear against the upwardly presented surface of yoke 40 adjacent to each end thereof. A pair of bolts 42 are threaded through framework 18 and into yoke 48 substantially at the midpoint thereof. Adjustment of bolts 42 permits rotation of yoke 40 and its cylinder as indicated by arrow 43 (Figure 3). Ad-

justment of set screws 41 permits rotation of yoke 40 and cylinder 38 in the direction of arrow 44 (Figure 4). Furthermore, these adjustments permit vertical adjustment with respect to the workpiece. As shown most clearly in Figures 4 and 5 in connection with cylinder 38, each cylinder is supported in its yoke so as to engage wires 27. When framework 18 is bolted on base 17 the threaded cylinders 38, 39 each engage the wires 27 on opposite sides of workpiece 32. The threads serve to accurately space wires 27 with respect to each other and also establish a pre-determined spacing between wires 27 and the surface of workpiece 19 exposed to the apertures of the mask. Thus, framework 18 may be removed from base 17 and, so long as workpiece holder 19 and workpiece 32 supported therein are not disturbed, precise registration of the apertures with the portions of the workpiece previously exposed to the apertures is assured. Where strips of different width are formed, as in the case of superimposed layers of different width, it is convenient to replace wire masking grill 15 having wires 27 of a given diameter with a masking grill having the same number of wires per inch but of a different diameter. Now even though mask 15 has been replaced by a substitute mask formed of wires of dilferent diameter, proper precise registration between the portions of the workpiece and the apertures between the wires is once again assured by the engagement of the wires with the alined threads of cylinders 38, 39. Furthermore, accurate uniform spacing between the wires is also attained.

Evaporator 12 is rotatably and adjustably mounted on platform 45 (Figure 1). Heating element 46 is conveniently mounted so as to overhang compartments for different materials formed in evaporator 12 and is energized by means of leads 47 sealed through platform 45 as indicated. A flap 48 is rotatably mounted on a rod 49 so that it may be swung into and out of position between evaporator 12 and jig 10.

The various movements of the movable parts within bell 11 may be effected in any convenient manner. For example, as indicated in Figure 1 each of the operating rods are connected through suitable gear trains and rotatable seals through platform 45, to control knobs mounted outside of bell 11. Such rotatable seals are well known and permit rotation of the rods which extend therethrough to effect the desired movement of the various parts within bell 11.

In operation a workpiece 32 is mounted in workpiece holder 19 and framework 18 is bolted to base 17. Movable mask 16 is adjusted to the desired location and a first set of layers or strips is formed on the workpiece by evaporating suitable material from evaporator 12. The evaporated material passes up through the aperture or apertures of movable mask 16 and the apertures formed beween the wires of fixed mask 15 to reach the exposed portions of workpiece 32. Other layers or strips may be formed intermediate those previously formed by stopping the evaporation of material by swinging flap 43 into posi' tion between workpiece and the evaporator. Heating element 46 is turned off and without disturbing bell 11 adjustments are made to shift workpiece holder 19 as indicated by arrow 34. Now the portions of workpiece 32 having the previously formed coatings thereon are in the shadows caused by the mask while other portions are now exposed to the apertures of the masks. In view of the engagement of the wires 27 with the threads of precision threaded cylinders 38, 39 all of the coatings thus formed are of uniform width. Furthermore the uniformity of the coatings formed is enhanced by the fact. that wires 27 are constrained by engagement with cylinders 38 and 39 to extend in a given plane accurately spaced from the workpiece. When it is desired to form another set of layers, as for example a narrower layer, on those already formed framework 18 is unbolted from base 17. This may be readily accomplished without disturbing the relationship between workpiece 32, workpiece holder 19, cylinders 38 and 39 and framework 18.

Fixed mask 18 is removed by unbolting frame 30 and a second mask in its supporting frame is mounted in its place. The second mask has the same number of wires per inch as the first one but the diameter of the wires is larger thereby defining apertures which are narrower than those formed by the first mask. Now framework 18 is once again bolted in place on base 17 with the threads of cylinders 38 and 39 each engaging corresponding wires of the second fixed mask. The proper spacing between the wires of the fixed mask and the surface of workpiece 32 is automatically insured. Furthermore, by their engagement with wires of the fixed mask, the threads on cylinders on 38 and 39 insure proper spacing between the wires and also registration of the apertures between the wires with respective portions of the surface of workpiece 32.

From the foregoing it is apparent that we have provided an improved apparatus for precisely forming coatings or strips which are arranged in accurate relation on a workpiece. Such an apparatus is particularly useful in forming the target of a pickup tube for producing simultaneous color video signals such as are described in another application of P. K. Weimer, Serial No. 344,497, filed simultaneously herewith and assigned to the assignee of this application. Such targets may include extremely narrow filter strips with conductive signal strips superimposed one on each of the color filter strips. The various strips are extremely narrow for example the color filter strips may be approximately .002 inch wide while the signal strips may each be approximately .0015 inch wide. In forming such superimposed strips it is necessary that each signal strip extend along only one filter strip and be centered thereon to avoid among other things short circuiting between adjacent signal strips and improper color rendition. Our apparatus not only insures a high degree of uniformity between successively formed adjacent strips but also makes possible ready registration of the superimposed strips on those previously formed.

While we have described our invention in connection with the apparatus shown it is believed that obvious changes and variations may be made therein without departing from our invention. It is, therefor, intended that all such changes and variations as come within the scope of the appended claims be included within our invention.

What is claimed is:

1. In an apparatus for depositing material in accurate relation on a surface of a workpiece, a base, a framework for supporting said workpiece and removably connected to said base, at least one mask on said base and including a plurality of elongated elements defining elongated apertures through which material may travel to portions of said surface, and means connected to said framework and engaging each of said elements and accurately locating said elements with respect to said workpiece.

2. In an apparatus for depositing material on a surface of a workpiece for forming layers in accurate relation thereon, a base, means removably supported on said base for supporting a workpiece, a plurality of flexible elongated elements supported in spaced relation on said base and forming a plurality of elongated apertures through which the material may travel to said workpiece, and grooved means connected to said removable means and engaging each of said elements and accurately positioning said elements with respect to said workpiece.

3. In an apparatus for depositing material on a surface of a workpiece for forming layers in accurate relation thereon, a base, a framework for supporting said workpiece and removably connected to said base, a wire masking grill including a plurality of wires supported on said base and connected thereto, and means connected to said framework and removable therewith engaging the wires of said grill and positioning the same.

4. In an apparatus for coating layers in accurate relation on a surface of a workpiece, a base, a framework for supporting said workpiece and removably connected to said base, a wire masking grill supported on said base and connected thereto, said wire masking grill including a plurality of wires, and threaded means connected to and removable with said framework, the threads of said threaded means engaging the wires of said grill and positioning the same.

5. Apparatus for mounting a workpiece in accurate spaced relation with the apertures of a mask, comprising a base, a mask connected to said base, a plurality of spaced elements on said mask and defining a plurality of apertures therebetween, a framework for supporting said workpiece and removably connected to said base, a pair of members connected to said framework and removable therewith, said members each having a plurality of grooves formed in the surface thereof with the grooves in one member alined with the grooves in the other member, there being a groove on each of said members for each of the elements of said mask, and said elements each being seated in said alined grooves.

6. Apparatus for mounting a workpiece in accurate spaced relation with the apertures of a mask, comprising a base, a wire masking grill connected to said base, a plurality of wires included in said wire masking grill, a framework for supporting said workpiece and removably connected to said base, a pair of members connected to said framework and removable therewith, said members each having a plurality of grooves formed in the surface thereof with the grooves in one member alined with the grooves in the other member, there being a groove on each of said members for each of the wires of said masking grill, and said wires each being seated in said alined grooves.

7. Apparatus for mounting a workpiece in accurate spaced relation with the apertures of a mask, comprising a base, a wire masking grill connected to said base, the wires of said grill defining a plurality of apertures therebetween, a framework removably connected to said base for supporting a workpiece, a pair of members each having accurately spaced threads formed on the surface thereof and with the threads of one alined with the other, means adjustably supporting said members on said framework in spaced relation, and each of said wires being engaged by the alined threads and positioned in accurate spaced relation.

8. Apparatus for mounting a workpiece in accurate spaced relation with the apertures of a mask, comprising a base, a wire masking grill connected to said base with the wires thereof defining a plurality of apertures, a framework removably connected to said base, a workpiece holder for supporting a workpiece in a given position and supported on said framework, a pair of members one on each of the opposite sides of said holder and each having a plurality of alined grooves formed in the surface thereof, there being a groove in each of said members for each of said wires, and each of said wires being seated in alined grooves of said members with the surfaces forming said grooves maintaining said wires in accurate spaced relation one with the other and with said holder.

9. In an apparatus for successively forming juxtaposed as well as superimposed layers in accurate relation on a workpiece, a base, a pair of support members connected to said base, a plurality of spaced apart wires connected to said support members and supported thereby, said wires defining a plurality of apertures therebetween, a framework removably connected to said base and having a guideway formed therein, a holder slideably mounted in said guideway and for supporting a workpiece, means for maintaining said holder in a given position on said guideway, a pair of locating members one on each of the opposite sides of said holder and adjustably connected to said framework in accurate spaced relation with said holder, said locating members each having a plurality of grooves formed therein one for each of said wires, the grooves of one of said locating members being alined with the corresponding grooves of the other, and each of assess-t 7 said wires being seated in the alined grooves of said locating members with the surfaces forming said grooves maintaining said wires in accurate spaced relation one with the other and with said holder.

10. In an apparatus for successively forming juxtaposed as well as superimposed layers in accurate rela tion on a "workpiece, a base, a pair of support members connected to said base, a plurality of spaced apart wires connected to said support members and supported thereby, said wires defining a plurality of apertures therebetween, said base having a guideway formed therein, a movable maskslideably mounted in said guideway and having at least one aperture formed therein, a framework reniovably connected to said base and having a guideway formed therein, a holder sl'ideably mounted in said guideway and for supporting a workpiece, means for main taining said holder in a given position in its guideway, means for registering the aperture of said movable mask with given portions of said workpiece, a pair of locating References Cited in the file of this patent UNITED STATES PATENTS 2,260,471 McLeod Oct. 28, 1941 2,391,595 Richards et a1. Dec. 25, 1945 2,453,582 Morgan Nov. 9, 1948 2,507,958 Cassman May 16, 1950

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