IL99275A - Method and apparatus for exposing a substrate to radiation particularly useful for applying a painted border around a windshield plate - Google Patents

Description

nemo 3'30 nnun mny enn>e τηι>Μ METHOD AND APPARATUS FOR EXPOSING A SUBSTRATE TO RADIATION, PARTICULARLY USEFUL FOR APPLYING A PAINTED BORDER AROUND A WINDSHIELD PLATE METHOD AND APPARATUS FOR EXPOSING A SUBSTRATE TO RADIATION, PARTICULARLY USEFUL FOR APPLYING A PAINTED BORDER AROUND A WINDSHIELD PLATE The present invention relates to a method and apparatus for exposing a substrate to radiation according to a predetermined pattern recorded on a mask. The invention is particularly useful for applying a border of opaque material around a windshield plate, such as described in our prior Israel Patent Specification 88886 filed January 5, 1989, and is therefore described below with respect to this application.

Our prior Patent Specification 88886 describes a method and apparatus for applying a pattern to a substrate, and particularly for applying a border of opaque material around an automobile windshield plate for covering a seal joining the windshield and the vehicle; body. The described method and apparatus involve the following operations: (a) coating the substrate (e.g., the windshield plate) with an initial pattern, to include the precise surface to be occupied by the final pattern (e.g., a border of opaque material), with a liquid substance which, when subjected to a predetermined type of electromagnetic radiation, hardens and binds itself to the substrate; (b) exposing the precise surface of the coated substance to be occupied by the final pattern to the predetermined type of electromagnetic radiation to cause the coated substance to harden and to bind itself to the substrate; and (c) removing the portions of the coated substance not exposed to the electromagnetic radiation. That patent specification describes a number of ways of performing operation (b) . One technique involves a single-shot flood illumination of the substrate via a mask of the final pattern; a second technique involves moving a light source over a fixed mask of the final pattern to trace the final pattern on the substrate; and a third method involves moving a laser beam to trace the final pattern.

The present invention is directed primarily to operation (b) of the above method, and is particularly advantageous where, as in the case of producing a border on a vehicle windshield, the substrate is of relatively large surface area.

According to the present invention, there is provided a method of exposing a substrate of relatively large surface area to radiation according to a predetermined pattern recorded on a mask, comprising: progressively recording the predetermined pattern on a mask in the form of a continuous strip; supporting the continuous strip mask between a source of the radiation and the substrate; and effecting relative movement between the radiation source and the substrate to progressively scan the surface of the substrate with , ' radiation, while at the same time moving the continuous strip mask relative to the radiation source, such that portions of the pattern on the continuous strip mask progressively become aligned with their corresponding portions of the substrate as the substrate is progressively scanned by the radiation source.

According to further features in the described preferred embodiment, the radiation source is moved relative to the substrate; in addition, the continuous strip mask is carried by the radiation source. More particularly, the continuous strip mask is progressively wound from a supply reel onto a take-up reel during the progressive scanning of the substrate with radiation.

According to further features in the described preferred embodiment, the radiation source and continuous strip mask are carried by a common head which is pivotally mounted about an axis perpendicular to the surface of the substrate to be exposed. The head is moved in a plurality of rectilinear scanning lines while the head is fixed about its pivotal axis during each such scan. The head is pivotted before starting a scanning line where the respective scanning line' requires a different orientation of the head than the preceding scanning line.

A method of exposing a substrate to radiation in accordance with the above features is particularly advantageous where the substrate is of relatively large surface area/ such as in the case of a vehicle windshield. Thus, the energy of the light source can be concentrated to a relatively small region of the substrate, which thereby allows very high intense radiation to be used in the exposure, as compared for example in the one-shot flood-illumination technique. In addition, the mask can be embodied in a relatively compact cassette which can be conveniently replaced by another cassette mask when the pattern to be marked is to be changed.

According to further features in the described preferred embodiment, there are two of such heads located on the opposite sides of the substrate. The two heads are simultaneously operated and controlled such that each head exposes one side of the i substrate with one-half of the predetermined pattern. This feature substantially decreases the time for processing the substrates, particularly automobile glass plates such as windshield plates.

The invention also provides apparatus for exposing a substrate to radiation in accordance with the above method.

Further features and advantages of the method will be apparent from the description below.

The invention is herein described, by way of example only, with reference to the accompanying drawings, wherein: Figs. 1 and 1a-1c illustrate four stages in the method of applying a final pattern in the form of a border of opaque material adjacent to and around a windshield plate in accordance with the present invention; Fig. 2 illustrates an overall system for performing the method of Figs. 1a and 1c; Fig. 3 illustrates a windshield plate mounted on a table in the radiation-exposure apparatus for performing the radiation -exposure operation of Fig. - 2; Figs. 4, 5 and 6, are side, top and end views, respectively, illustrating one form of apparatus for performing the radiation-exposure operation; Fig. 7 diagrammatically illustrates one form of radiation head for use in performing the radiation-exposure operation; Fig. 8 illustrates how the windshield plate is divided into a plurality of rectilinear scanning lines for performing the radiation-exposure · operation; and Fig. 9 diagrammatically illustrates how a continuous strip mask may be produced for performing the radiation-exposure operation.

Fig. 1 illustrates a windshield plate WP after it has been cut and ground to proper size and configuration, but before a final pattern, in the form of a painted border (CS^ , Fig. 1c), has been applied around its outer edge. Such a border of opaque material is used to cover the seal which is subsequently applied to sealingly bond the windshield to the vehicle body. Figs, la-lc illustrate how this final pattern CS1 is applied.

Thus, as shown in Fig. 1a, the surface of the windshield plate WP adjacent to and around its outer edge, including the precise surface to be occupied by the final pattern of opaque material, is coated with a liquid substance CS which, when subjected to a specific type of electromagnetic radiation, hardens and binds itself to the windshield WP. Such a coating is applied as an imprecise initial pattern to completely coat at least the precise surface to be covered by the final pattern of 'opaque coating.

The precise surface of the windshield plate rWP to be occupied by the final pattern CS^ (opaque coating) is then exposed to the selected type of electromagnetic radiation, e.g., ultraviolet light, which causes the coated substance CS of the final pattern CS1 to harden and to bind itself to the windshiel d plate (Fig. lb) . The remaining portion of the coating not exposed to the electromagnetic radiation, indicated as CS2 does not harden nor bind itself to the windshield plate.

The portions of the coating (CS2, Fig. 1b), which has not been exposed to the radiation is then removed by washing away, leaving the final pattern CS1 (Fig. 1c) which has been exposed to the electromagnetic radiation.

Fig. 2 illustrates a system which may be used for performing the above-described operations illustrated in Figs. 1a-1c. Briefly, this system comprises a loader unit 202 on which the windshield plates WP are initially loaded, a coating unit 204 for performing the coating operation described with respect to Fig. 1a, a radiation unit 206 for exposing the coating to radiation to produce the final pattern CS^ (Fig. 1b), a washing unit 208 for washing away the non-exposed portions of the coating to leave the final pattern CS^ , and an unloader unit 210 for unloading the windshield plates with the final pattern CS-j . Each of the units illustrated in Fig. 2 may be of the construction as described in the above-cited Patent Specification 88886, except for the radiation-unit 206, which unit is of a novel construction as described more particularly below with reference to Figs. 3-7.

The radiation unit 206 includes a base 212 supporting a horizontal table 214 which receives the windshield plate WP. A pair of conveyor belts 216 (Fig. 3) pass over the upper surface of table 214 to convey each windshield plate to a predetermined position on the table as defined by the position of a roller 218 engageable with the leading edge of the windshield plate. When the windshield plate WP is properly positioned by roller 218, it is clamped in this position between a piston 219 actuated by a cylinder 220, and a wall 222 at the opposite side of the table. Roller 218 is selectively positionable to the proper position, according to the particular size and configure ion and windshield plate being processed, by a feed screw 224 driven by a motor MR.

A carriage 226 (Figs. 4-6), in the form of a gantry bridge, is mounted over the upper face of table 214 and is movable along the Y-axis (vertically, Fig. 5) by a pair of lead screws 226a, 226b driven by a pair of motors Mya, Myb, having encoders Eya, Eyb. The Y-carriage 226, in turn, carries two X-carriages 228a, 228b, driven along the X-axis by lead screws 230a, 230b and motors Mxa, Mxb, each having encoders Exa, Exb. Each of the X-carriages 228a, 228b carries a radiation head 230a, 230b.

Both heads 230a, 230b are of the same construction as illustrated by head 230 in Fig. 7.

Thus, each radiation head includes a radiation source 231 mounted at the focal point of a parabolic reflector 232 so that the radiation is reflected parallel to the optical axis of the radiation head. The radiation is shaped by an aperture plate 233. It is then reflected 90° by a first reflector 234, and a second reflector 235, through a cover plate 236 towards the table 214 carrying the windshield plate WP to be exposed to the radiation.

Radiation source 231 is a source rich in ultraviolet light, but also contains infrared light. Reflector 234 reflects most of the ultraviolet light via reflector 235 towards the windshield plate WP on table 214, whereas most of the infrared light passes through reflector 234 and is dissipated by a fan 237.

Interposed between light source 231 , and particularly its reflector 235, and the windshield plate support on table 214, is a mask, generally designated 240, having the final exposure pattern (CS_. ) recorded thereon. In this case, the mask is transparent to the ultraviolet radiation at the i portions of the coated substance to be hardened and bound to the windshield to produce the final patter CS^ (Figs. 1b and 1c), and is opaque to the remaining portions of the pattern corresponding to the portions (CS2) of the coated substance to be removed during the washing operation of unit 208 in Fig. 2.

The mask 240 is in the form of a continuous strip. It is wound between a supply reel 241 and a takeup reel 242 and extends across the output reflector 235 of the radiation head. The pattern is recorded on strip 240 in a progressive manner, as will be described more particularly below with respect to Fig. 9, such that one end of the strip mask 240 records the beginning portion of the pattern, and the opposite end records the end portion of the pattern. The strip mask 240 can be embodied in a cassette, including guide rollers 243, 244, guiding the strip as it is progressively moved across the outlet window 236 of the radiation head 230.

As will be described more particularly below, the strip mask 240 is unwound from its supply reel 241 to its takeup reel 242 to progressively expose the pattern recorded thereon over the windshield plate supported on table 214. At the same time, the radiation head 230 is also moved, relative to table 214, such that the portions of the pattern on the strip mask 240 progressively become aligned with their corresponding portions of the windshield plate supported on table 214 to be exposed to the recorded pattern; i.e., there is relative movement between the head and the windshield plate, but no relative movement between the respective portions of the strip mask and the windshield plate, during the radiation exposure.

The two radiation heads 228a, 228b (Figs. 4-6) are each pivotally mounted about their own longitudinal axis, and each is pivotted by its own rotary motor Mra, Mrb, each having an encoder Era, Erb. The two radiation heads 230a, 230b are thus moved together along the Y-axis by the Y-carriage 226, but each may be moved independently along the X-axis, by the X-carriages 228a and 228b, respectively, each by its own motor Mxa, Mxb, and may also be pivotted about its own longitudinal axis by its individual motor Mra, Mrb.

The radiation unit 206 (Fig. 2) is operated in the following manner: After the windshield plate WP has been coated in the coating unit 204 around its outer edge, producing the initial imprecise coating CS in Fig. 1a, the windshield is conveyed to the radiation unit 206 by the conveyor belt 216. There it is located in proper position on table 214 by rotor 218 and is clamped in position by piston 219.

Each of the radiation heads 230a, 230b had been previously loaded with a mask in the form of a continuous 'strip 240 contained in a cassette received by the respective radiation head. Each radiation head acts only on one-half the periphery of the windshield plate WP, and therefore the strip mask of each cassette has recorded thereon only one-half the pattern to be applied to the windshield plate.

As shown in Fig. 8, the two radiation heads 230a, 230b are both located at the start point S, and are moved in opposite directions along the X-axis, but in the same direction along the Y-axis, to scan the respective half of the outer periphery of the windshield plate WP, until they both arrive at the end point E, at which time the two heads will have scanned the complete outer periphery of the windshield plate.

As also shown in Fig. 8, the two radiation heads are moved along rectilinear scanning lines . Each scanning line is of sufficient width and length so as to scan the respective portion of the windshield plate WP to be occupied by the final pattern CS^ . At the beginning of each rectilinear scan line, the radiation heads 230a, 230b are pivotted about their longitudinal axes by their rotary motors Mra, Mrb, to assure that the rectilinear line to be scanned will cover the final pattern CS^ for the respective portion of the periphery of the windshield plate.

Thus, at the start of the exposure operation, the two radiation heads 230a, 230b are located at opposite sides of the starting point S in Fig. 8, at the beginning of the first scanning line SL^ , SL^ . Then both heads are moved in opposite directions to the ends of their respective scanning lines. As the two heads are thus moved relative to the windshield plate supported on table 214, the strip masks 240 in the two heads are operated to progressively align the portions of the patterns recorded thereon with their respective portions of the windshield plate, so that there is no 992 . relative movement between the masks and the windshield , ' plate at the time of the exposure. That is to say, the strip masks 240 are effectively "rolled onto" the surface of the windshield plate as their radiation heads 230 traverse their respective scanning lines along the outer circumference of the windshield plate.

As soon as one scanning line has been completed, e.g., scanning lines SL¾1 , SLfa1 , the radiation heads are pivotted, if necessary, about their respective longitudinal axes by their motors M , M , before^ arting he next scanning line (e.g., SLa2, ) ■.>. o assure that in their complete traverses of the next scanning lines they will expose the pertinent portions of the final pattern CS.. of coating substance to be fixed to the windshield.

Similarly, the radiation heads 230a and 230b are adjusted so that the scanning lines SL^, SL^; SLa4, SLb4; SLa5, SLb5; are drawn on the windshield plat, as shown in Fig. 8.

Fig. 9 illustrates one way of producing Jhe continuous strip masks from a standard windshield plate WPg having the desired final pattern CS1g recorded thereon. Thus, a cassette loaded with film, e.g., 70 mm, is moved in 70 mm increments around the outer periphery of the standard windshield plate WPg, and, at each such increment, exposes 70 mm of the standard pattern CS1S.

The standard pattern is thus recorded in increments in a continuous strip of film. Two suchcassettes can be used", each corresponding to one of the radiation heads 230a, 230b, for recording the strip film of the respective head. Alternatively, the recording process can be done by one camera, in which case the resulting film would be divided into two sections, one for each of the radiation heads.

The method and apparatus described herein are capable of producing very high intensity light exposure with commercially available and relatively inexpensive radiation sources. For example, the radiation heads included in the described apparatus may use standard 1,500 watt Hg-Xe lamps. The described arrangement also provides a compact radiation head which incorporates its respective mask, and which mask can be conveniently changed by merely changing cassettes. Further, by using two such heads the required time of exposure is substantially halved.

While the invention has been described with respect to one preferred embodiment, it will be appreciated that many variations, modifications and other applications of the invention may be made.

Claims (23)

1. WHAT IS CLAIMED IS:
2. 2. . A method of exposing a substrate of relatively large surface area to radiation according to a predetermined pattern recorded on a mask, comprising: progressively recording said predetermined pattern on a mask in the form of a continuous strip; supporting said continuous strip mask between a source of the radiation and the substrate; and effecting relative movement between said radiation source and said substrate to progressively scan the surface of the substrate with radiation, while at the same time moving said continuous strip mask relative to said radiation source, such that portions of the pattern on the continuous strip mask progressively become aligned with their corresponding portions of the substrate as the substrate is progressively scanned by the radiation source. i . The method according to Claim 1 , wherein said radiation source is moved relative to said substrate during the scanning thereof.
3. 3. The method according to Claim 2 , wherein said continuous strip mask is carried by said radiation source .
4. 4. The method according to Claim 3, wherein said continuous strip mask is progressively wound onto a take-up reel during the progressive scanning of the substrate with radiation.
5. 5. The method according to Claim 4, wherein said radiation source and continuous strip mask are carried by a common head which is pivotally mounted about an axis perpendicular to the surface of the substrate to be exposed; said head being moved in a plurality of rectilinear scanning lines while the head is fixed about its pivotal axis for each such scanning line, the head being pivotted before starting a scanning line where the respective scanning line requires a different orientation of the head than the preceding scanning line.
6. 6. The method according to Claim 5, wherein there are two of said heads located on the opposite sides of said substrate, said heads being simultaneously operated and controlled such that each head exposes one side of the substrate with one half of the predetermined pattern.
7. 7. ?. The method according to any one of Claims 1-6, wherein said mask is transparent to the electromagnetic radiation at the portions thereof to contain the pattern.
8. 8. The method according to any one of Claims 1-7, wherein said radiation is ultraviolet light from a radiation source radiating both ultraviolet light and infrared light, said radiation being directed to a selective reflector which passes substantially only said ultraviolet light to said continuous strip mask.
9. 9. A method of applying a marking to a substrate, comprising the following operations: (a) coating the surface of the substrate with an initial pattern, to include the precise surface to be occupied by a final predetermined pattern, with a liquid substance which, when subjected to a predetermined type of electromagnetic radiation, hardens and binds itself to the substrate; (b) exposing the precise surface of the coated substance to be occupied by said final predetermined pattern to, said predetermined type of electromagnetic radiation to cause said coated substance to harden and to bind itself to the substrate; and (c) removing the portions of said coated substance not exposed to said electromagnetic radiation; characterized in that operation (b) is performed in accordance with the method of any one of Claims 1-8.
10. 10. The method according to Claim 9, wherein said substrate is an automobile glass plate.
11. 11. The method according to Claim 9 , wherein said substrate is a windshield, and said final predetermined pattern is an opaque coating applied to the border around the periphery of the windshield.
12. 12. Apparatus for exposing a substrate of relatively large surface area to radiation according to a predetermined pattern recorded on a mask, comprising: a source of radiation; a mask in the form of a continuous strip having said predetermined pattern progressively recorded thereon; means for supporting said continuous strip mask between said source of radiation and the substrate; and means for effecting relative movement between said radiation source and said substrate to progressively scan the surface of the substrate with radiation via said mask, while at the same time moving said continuous strip mask relative to said radiation source, such that portions of the pattern on the continuous strip mask progressively become aligned with their corresponding portions of the substrate as the substrate is progressively scanned by the radiation source .
13. 13. The apparatus according to Claim 12 , wherein said substraste is supported on a fixed support, and said radiation source is moved relative to said substrate during the scanning thereof.
14. 14. The apparatus according to Claim 13 , wherein said continuous strip mask is carried by said radiation source.
15. 15. The apparatus according to Claim 14 , wherein said continuous strip mask is initially wound on a supply reel and is progressively transferred to a take-up reel during the progressive scanning of the substrate with radiation.
16. 16. The apparatus according to Claim 15, wherein said radiation source and continuous strip mask are carried by a common head.
17. 17. The apparatus according to Claim 16, wherein said head is pivotally mounted about an axis perpendicular to the surface of the substrate to be exposed; said apparatus further including drive means for driving said head along a plurality of rectilinear scanning lines, and pivot means for pivotting the head before starting a scanning line where the respective scanning line requires a different orientation of the head than the preceding scanning line.
18. 18. The apparatus according to Claim 17 , wherein there are two of said heads located on the opposite sides of said substrate and are simultaneously operated and controlled such that each head exposes one side of the substrate with one half of the predetermined pattern.
19. 19. The apparatus according to any one of Claims 12-18, wherein said mask is transparent to the electromagnetic radiation at the portions thereof to contain the pattern.
20. 20. The apparatus according to any one of Claims 12-19, wherein said radiation is ultraviolet light from a radiation source radiating both ultraviolet light and infrared light, said radiation being directed to a selective reflector which passes substantially only said ultraviolet light to said continuous strip mask.
21. 21. A system for applying a marking to a substrate, comprising: (a) means for coating the surface of the substrate with an initial pattern, to include the precise surface to be occupied by a final predetermined pattern, with a liquid substance which, when subjected to a predetermined type of electromagnetic radiation, hardens and binds itself to the substrate; (b) means for exposing the precise surface of the coated substance to be occupied by said final predetermined pattern to said predetermined type of electromagnetic radiation to cause said coated substance to harden and to bind itself to the substrate; and (c) means for removing the portions of said coated substance not exposed to said electromagnetic radiation; characterized in that means (b) includes the apparatus of any one of Claims 12-20.
22. 22. The method of applying a border of opaque material around an automobile windshield plate, substantially as described with reference to and as illustrated in the accompanying drawings.
23. 23. Apparatus for applying a border of opaque material around an automobile windshield plate, substantially as described with reference to and as illustrated in the accompanying drawings. Advocate, Patent Attorney P.O. Box 23008 Tel-Aviv 61 230 ;