DE2751680A1 - SWITCH MATRIX, IN PARTICULAR TRANSPARENT SWITCH MATRIX, FOR KEY AREA DEVICES - Google Patents

Description

Henkel, Kern, Feiler Ct Hanzel patent attorneys

.6-27 5168Q

Möhlstrasse 37 Control Data Corporation D-8000 Munich 80

Minneapolis, Minn., V.St.A. Tel .: 089 / 982085-87

Telex: 0529802 hnkld

Telegrams: ellipsoid

Nov 18, 1977.

Switch matrix, especially transparent switch matrix,

for touch pad devices

The invention relates to a touch or touch surface device, which electrically indicates the X-Y coordinates of their touch with the finger of an operator and that only responds to pressure. Often, information is also displayed on a substrate below the load surface. The contact coordinates can be related to the displayed information or adjusted to thereby a to ensure an interactive connection between the operator and the device, part of which is the touch surface represents.

Numerous devices for determining the point of contact on a surface are known. The device that comes closest to the invention is probably a so-called. Tensioned ear drum ellmesibran _; This device uses a membrane which is arranged at a distance from a flat substrate and which is deflectable in such a way that conductors carried by it with it

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which are brought into contact on the substrate · Another Apparatus of this type is described in an article published in "Control Engineering?" July 1976, pp. 33-34, entitled "CRT Touch Panels Provide Maximum Flexibility in Computer Interaction". This article describes one curved or arched, flexible plastic film, the thin Carries wires. The foil is deflectable to bring these wires into contact with a perpendicular set of similar wires mounted immediately below. The two sets of wires are separated by spacers. U.S. Patent No. 3,760,360 discloses one very similar device in the form of a flat board or plate, but which is incapable of providing an interactive or side-by-side display of information. U.S. Patent 3,495,232 describes a somewhat simpler embodiment of a similar device. In U.S. Patent 3,921,167 there is a surface or panel described, which responds position-sensitive to the approach of an outer probe for measuring changes in capacitance.

The touch surface according to the invention, on the other hand, spans a rigid substrate, the surface of which has a predetermined radius of curvature of infinite (flat) up to about 63.5 cm or less possesses, and it consists in part of an elastic membrane which has a contour adapted to the substrate surface and attached to the perimeter of the substrate. Is on the surface of the substrate facing the membrane a group of separate conductor strips or lines attached or glued. A second set of separate ladder strips or trains that are able to bend with the membrane and cross the first conductor strips, is removed from the membrane carried on their surface facing the substrate. When pressure is exerted from the outside on a localized point on the membrane, one or more conductor strips are in electrical contact with one or more conductor strips of the sub-

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strats urged. By determining who are in contact with each other Standing conductor strips can give the approximate coordinates of the location of the pressure exerted on the membrane be determined. To prevent short-circuiting between the strips in each group when there is no external pressure, Any of several possible means can be used. In a special embodiment is a thin, transparent insulating grid is inserted between the two groups of conductor strips. A pressure-resistant one (Piezo-resistant) coating on the surfaces of at least one group of conductor strips also appears to be satisfactory to act. If a curved membrane is used, there is a third possibility of preventing a short circuit in choosing the radius of curvature of the membrane somewhat smaller than that of the substrate. The inherent elasticity appears here the membrane to be sufficient, the conductor strips carried by it without an interposed element at a distance of to hold the conductor strip of the membrane.

In a preferred embodiment, the rigid substrate consists of a curved cathode ray tube screen, the elastic membrane being adapted to the screen with respect to its curvature. The conductor strips of both the substrate and the membrane are so thin that they are transparent and thus the viewing of the Allow information displayed on the screen. As a result of their transparency, the conductor strips can be relatively wide in comparison to the mutual spacing on the same area, and thereby ensure a larger contact area. The short-circuit preventing means consist of an insulating grid, preferably of one of the numerous photoresistive polyesters currently available, so that the grid can be formed in place on the substrate or on the membrane by masking and exposing the component in question accordingly and then after a corresponding chemical

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Procedure is dealt with. Such photoresist materials are practically transparent at the intended small thicknesses.

The object of the invention is thus to create a passive surface that reacts to a slight pressure with the finger or a stylus or /. Pen responds.

In particular, the invention aims to create a touch surface, which allows viewing of the representation or display reproduced under it and which can be easily understood can be integrated into existing display device constructions.

This object is achieved by the features and deficiencies characterized in the attached patent claims.

In the following, preferred embodiments of the invention are explained in more detail with reference to the accompanying drawings. Show it:

1 shows a plan view of a corner section of a typical, flat or curved touch surface arrangement according to FIG Invention,

Fig. 2 shows a cross section through a curved embodiment the touch surface according to FIG. 1 with a membrane which has a slightly smaller radius than the substrate,

3 shows an enlarged detail from FIG. 2 to illustrate the positional relationship between the two Conductor strip sets and the insulating grille, if present,

4 shows a further enlarged detail from FIG. 3, which shows the positional relationship between the shows both conductor strip sets and the insulating grid, and

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FIG. 5 shows an enlarged detail from FIG. 2 for illustration the use of a pressure-resistant, short-circuit-preventing device.

In the figures, the scale representation of the individual parts is not always the same, because this representation contributes to a better understanding of the invention. Appropriate dimensions of the components of the device are, if necessary, given in the description below.

The preferred embodiment of the invention according to FIG. 1, of which only a corner section is shown, comprises a carrier or a substrate 10 which can be flat or curved according to FIG. 2 and which must have an insulating surface. Conductor strips or tracks 20 24 running in the Y direction consist of transparent coating areas which adhere firmly to the surface of the substrate 10 facing the viewer. In a typical application, the substrate 10 can consist at least in part of the screen of a cathode ray tube. This may prove to be convenient to apply the conductor strips directly on such a screen or other substrate, but rather on a clear plastic sheet 55 which, if necessary, to conform to a curved screen is also curved form be Äann _t, which then Gluing or otherwise attached to the substrate 10. Connected to the ends of the strips 20-24 are leads 40-44 which are used to establish electrical contact between the strips and external electronic control devices. In a typical embodiment, each conductor strip 20-24 is now about 12.7 wide and separate from the adjacent strip separated by a 0.13 mm wide gap. In a special embodiment, the conductor strips are preferably produced from indium oxide or tin oxide or from a combination of both oxides. The conductor strips can be easily produced in that the overall

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surface of the substrate 10 is coated using conventional methods with the appropriate conductive material. The narrow spaces can then be removed by means of conventional etching processes using photoresist material be formed between adjacent conductor strips.

In one embodiment of the invention, the next Layer of the touch surface formed by an insulating grid 45 which extends over at least part of the conductor strips 20 and normally evenly covers conductor strips 20-24. Such an insulating grille can be made comfortably a commonly available, commercially available transparent photoresist material based on its properties are not conductive. The areas to be covered with the insulating grid 45 are covered with the photoresist material coated, whereupon a corresponding mask is placed on these areas, the photoresist material is exposed by the usual method and the unexposed portions of the photoresist material according to the usual chemical processes are removed. A suitable grid 45 consists of "cross hatching" or a network of lines of the photoresist material, each line having a width (w as shown in FIG. 4) of about 0.13 mm and all lines both in the vertical and in the horizontal direction at center-to-center distances (s according to FIG. 3) of about 0.64 mm are arranged from each other. The thickness of the insulating grid can vary as is desired for making a contact Pressure vary; however, a nominal thickness of about 0.0025 mm appears to be satisfactory for the one to be described Polyester membrane made of 0.08 mm thick MYLAR (registered trademark of DuPont Corp.). In general, a ratio of 1: 5 to 1: 100 for the width w of the insulating grid lines to the center-to-center distance s between each two adjacent lines for this grid thickness suitable. The width w of the individual lines may in any case not exceed a tenth of a millimeter

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(or a few thousandths of an inch). The insulating grille 45 can also be formed on the membrane 11 after the conductor strips 12-16 are on yet to be described Have been trained wisely "

The elastic, insulating membrane 11 forms the actual touch surface, which the operator can at a desired location presses to make an electrical contact indicating the coordinates of the pressure point. The membrane 11 carries on their surface facing the substrate 10 is conductor strips 12-16, which before the membrane 11 is attached to the substrate 10 are trained. The conductor strips 12-16 must be sufficiently elastic to easily move with to be able to bend the membrane 11. A clear polyester film with a thickness of 0.08 mm and with a clear, conductive gold layer on one surface, as it is from the company Sierracin Corp., 12780 San Fernando Road, Sylmar, CA, 91342 / USA, is for this purpose suitable, also in other thicknesses of at least 0.18 mm. The conductor strips are advantageously formed by that (e.g. by etching) narrow strips of the gold coating are removed from this foil in parallel lines will. Typical dimensions for the gold-free lines defining the gold plating strips 12-16 are width of 0.05 mm with center-to-center distances of 12.7 mm. A ventilation opening 50 ensures that the membrane 11 resumes its original shape more quickly after the pressure is exerted on it can, in that the air flows faster into the space between membrane 11 and substrate 10. Preferably a filter can be inserted into the ventilation opening 50, to prevent the entry of impurities. This ventilation opening thus prevents resetting that is too slow the diaphragm 11 to its original shape when it is moved over a large area by a single touch of pressure hinv / eg has been deflected. In addition, short

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Inferences prevented by fluctuating ambient air pressure be evoked.

If the substrate 10 is curved or arched, the membrane 11 and the strips already formed on it must 12-16 are brought into a uniform contour adapted to the substrate 10 by molding. This molding is hiring There is no particular problem with the polyester film used if this film is in accordance with one that has already been proposed Process is shaped. After the gold coating has been etched to form the conductor strips 12-16, the membrane 11 becomes brought into a shape according to the method mentioned, which is adapted to the shape of the substrate 10 substantially If the substrate 10 is curved, the curvature or curvature of the membrane 11 should preferably be in the unloaded state slightly larger than that of the substrate 10. If the substrate 10 consists of a typical, domed implosion protection shield a cathode ray tube, its curvature is approximately spherical with a radius of about 51 - 76 cm. In this case, the membrane 11 is preferably shaped to a radius of curvature which is around 25 .A - 101.6 mm is smaller than that of the substrate 10. The somewhat greater curvature or curvature prevents the conductor strips 12-16 on the membrane 11 are pulled too tightly against the conductor strips 20-, 24 and possibly short-circuited against them. In addition, such a dimensioning is then essential if, as will be described in more detail, other short-circuit preventing means than the grid 45 on a curved substrate can be used. The membrane 11 is secured around its edge by means of adhesive strips 54 in attached to the substrate 10 in such a position that the conductor strips 12-16 run over the individual conductor strips 20-24 and thereby through the grid 45 and the inherent tendency of the membrane 11, in the unloaded state, its resulting from the molding assume the arched state from the ladder strips

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20 - 24 are kept at a distance. The conductor strips 12-16 are with the help of a conductive adhesive the leads 32 - 36 connected, which in turn simultaneously with the formation of the conductor strips 20-24 in place, i.e. immediately upon the substrate 10 can be. The control electronics (support electronics) can then be readily connected to strips 12-16 will. Although not necessary in many cases, in some cases a spacer 53 (FIG. 2) can advantageously be used to prevent a short circuit can be provided around the edge of the membrane 11, in particular if other short-circuit preventive Means can be used as the grid 45. The spacer 53 does not need to rest on the conductor strips 20 - 24 and can extend up to the edge of the membrane 11.

In operation, contact between any of the conductor strips 20-24 and any of the conductor strips 12-16 can be made by light finger or pen pressure against the membrane 11 above the desired point of intersection. Because of the comparatively wide contact areas, the pressure point does not need to be exactly in the MitiP of the intended At the intersection. When arranging both the insulating grille 45, as well as the other short-circuit-preventing means to be described, becomes practical with light finger pressure Resistance-free contact is established between the two selected conductor strips. The wide contact areas offer also added reliability in making contact between the conductor strips.

FIG. 5 shows a modification of the short-circuit preventing means which can be used instead of the grid 45. The one before called, commercially available polyester film with gold coating is optionally also with a "legally protected Ceramic coating "available," which the permeability for

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increases visible light and provides a means of mechanical protection for the conductive metal damping "(Sierracin Corp. Brochure" Sierracin Intrex (TM) Electrically Conductive Film Components ^11. ) This coating has been shown to be the piezo-resistant or pressure-resistant Characteristic of high resistance under very light pressure and very low resistance under pressure no greater than gentle finger pressure. These optionally applicable coatings are indicated at 51 and 52 in FIG. If the provision is made, both coatings 51 and 52 must be present in order to ensure a resistance which is so great at very low pressure that the function as a short-circuit-preventing agent is maintained or remains. It is possible that if a coating of a greater thickness than is currently available is used, the coating 52 could be omitted. As mentioned, if an insulating grille 45 is not used, a spacer 53 may be necessary to prevent short-circuiting at the edges.

Another way to prevent a short circuiter ^ between the X- and Y-axis conductor strips 12-16 and 20-24, in the case of a substrate 10 with a finite curvature,

11 radius. If the radius of curvature of the membrane / according to Fig. 2 is selected to be smaller than that of the substrate 10 (of course for on the convex surface of the substrate 10 attached membranes), the X-axis conductor strips 12-16 by the inherent elasticity of the membrane 11 and their domed shape held at a distance from the Y-axis strips 20, creating a short circuit between the conductor strips is avoided in the absence of pressure. Although a wide range of radii of curvature is undoubtedly applicable, it is shown that a substrate with a radius of curvature of 635 mm and a 0.08 mm thick polyester membrane, which in a mold with a radius of curvature of 558.8 mm are satisfactory. According to FIGS. 1 and 2, it is in this case short-circuit preventive arrangement advantageous, the edge of the Membrane 11 outside the Y-axis strips 20-24 with the

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To connect or glue substrate 10 to increase the distance between the areas of the X- and Y-axis strips, The spacer 53 can also be provided for this purpose. It is likely, if not confirmed, that when utilizing the inherent elasticity and the curvature or curvature of the membrane 11 to ensure the required short-circuit protective distance between the X- and Y-axis strips, a greater difference in the radii of curvature of substrate 10 and membrane 11 is necessary than in the other, previously described embodiments, while namely with a substrate radius of 635 ana in all three cases a 76.2 mm smaller membrane radius is satisfactory is, when using the insulating grille 45 or the pressure-resistant Cover 51 has a radius difference of 25.4 mm or less are sufficient.

In the manufacture of the device according to the invention, it is it is essential that the surfaces of the conductor strips 20 - 24 and 12-16 are largely free of dust and other foreign bodies, when the membrane 11 is attached to the substrate 10. Due to the fairly wide contact areas between the intersecting strips, however, negligible amounts of such foreign objects can be neglected, in particular if these foreign bodies are not conductive.

In summary, the invention thus provides a switch matrix in the form of a position-sensitive touch surface for the arrangement created on a rigid substrate bearing a first set of conductive strips. One above the substrate arranged, elastic plastic membrane carries a second Set of conductive strips perpendicular to and spaced from the strips of the first set are. By means of finger pressure there is an electrical contact between any (any) strip of the first sentence and a strip of the second set can be produced. The substrate

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can be either flat or curved, with the membrane is adapted to its contour.

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Claims (1)

Henkel, Kern, Feiler ft Hänzel patent attorneys 27b 1680 Möhlstrasse 37 Control J-C ^. Corporation D 8000 Munich 80 -. i ^: nn, V Λ - \. Tel: 089.982085-87 ' ''" Teiex: 0529302 hnkld Taiegrams: ellipsoid U- _:. iq?> claims • Transparent switch matrix for attachment to the surface of a rigid, insulating substrate with a predetermined radius of curvature, in particular for a key area device, characterized by a number of spaced apart first conductor strips (20-24) firmly adhering to the surface of the substrate (10) , by an elastic, insulating membrane (11) with a true-to-shape or undeformed contour, practically corresponding to the predetermined curvature contour, which is attached to its peripheral edge in such a position on the surface of the substrate that the membrane contour is adapted to the substrate contour and the Membrane is arranged in a predetermined area thereof at a distance from the first conductor strips, and by a number of flexible, spaced-apart second conductor strips (12-16) which adhere firmly to the surface of the membrane facing the substrate, each at a distance of the harvested conductor strips arranged and thinner are formed as the distance between the first and second conductor strips and which at least two of the first-mentioned conductor strips cross and / or. cut. 1/097 lib IbtfU 2. Device according to claim 1, characterized in that first and second letters so; ie the wer.ibrnn 5: -ln i.lic.i transparent ~ ind. 3. Device nana claim 1, characterized gekennzeiclme; ,, 'i ^ ß the first conductor strips practically parallel to one another lie that the second ladders faithful also come in handy Are arranged parallel to one another and that the elastic ic.ie Membrane is arranged so that the zv / eir Leitero ^ reiien practically perpendicular to the first bar,;. mature to run come. 4. Apparatus according to claim 1, characterized in that the substrate is convexly curved or gev / oiled and daij di? Contour of iiemoran etv / as is more convex than that of the substrate. 5. Apparatus according to claim 4, characterized in that the substrate is spherically curved. 6. Apparatus according to claim 5, characterized in that the radius of curvature of the membrane is slightly smaller i: st than that of the substrate. 7. Apparatus according to claim 6, characterized in that the radius of curvature of the membrane is about 25.4 - 101.6 mm smaller than that of the substrate. 8. Apparatus according to claim 7, characterized in that the radius of curvature of the substrate is about 635 mm and that the undeformed radius of curvature of the membrane is about 533 - 610 mm. 9. Apparatus according to claim 1, characterized in that the elastic membrane is made of polyester film. 80982 1/0976 o8Ü Device according to claim 1, characterized in that an insulating layer is provided, the contour of which is the same egg substrate surface is adapted and the in to the Contour ^ es ouustrats touched position attached to the latter and on the other side the first ladder strips wearing. Device according to claim 10, characterized in that d & ß the insulating layer, the conductor strips and the membrane are transparent. Device according to claim 1, characterized in that the i'-substrate has a convex contour and the membrane is slightly more convergent or arched than the .7.substrat and that between the first and second conductor strips an insulating grid is inserted, which is provided with gaps, which an electrical contact between a first and a second conductor strip in one call to allow hand pressure at their intersection. Device according to Claim 1, characterized in that the first and second conductor strips are seen as a piezonzv /. pressure-resistant coating is inserted, the electrical contact between a first and a second conductor strip at one on their intersection pressure applied by hand. Device according to one of the preceding claims, characterized in that it is transparent and that an insulating grid is inserted between the first and second conductor strips, which is provided with gaps, which an electrical contact between a first and a second conductor strip at a point of intersection Allow hand pressure. 809821/0978 ORIGINAL INSPECTED / 7b IböO 15. The device according to claim 14, characterized in that the Insulating grid evenly covers the area occupied by the first conductor strip. 16. The device according to claim 14, characterized in that the insulating grille is made of a transparent or translucent material. 17. Apparatus according to claim 1 or 12, characterized in that that the insulating grid is made of an insulating photoresistive material is made. 18. The apparatus according to claim 12, characterized in that the insulating grid consists of lines extending at right angles to each other and that the ratio between the
Width of the individual lines forming the grid and
the distance between adjacent lines in the range of
1: 5 to 1: 100. 19. The device according to claim 18, characterized in that the thickness of the lines forming the insulating grid is approximately
Is 0.0025 mm. 20. A method for producing an insulating grille according to one of claims 12 to 19, characterized in that the
with the conductor strips coated substrate with a
Photoresistive material is coated that the photoresistive material is exposed to light in a pattern corresponding to a predetermined grid pattern that the
Photoresistive material is developed and that the photoresistive material between the individual grid lines
is removed chemically. 21. The device according to claim 13, characterized in that the pressure-resistant coating consists of a commercially available 809821/0976 There is a ceramic coating, which increases the permeability to visible light and provides mechanical protection offers. 22. The apparatus according to claim 21, characterized in that the first and second conductor strips each have one Wear a pressure-resistant cover. 23. Device according to one of the preceding claims, characterized in that the transparent, elastic Membrane has a ventilation opening which allows an air flow to enter the space between the membrane and the substrate leaves. 809821/0976