WO2003019594A1

WO2003019594A1 - Tape or ribbon switch

Info

Publication number: WO2003019594A1
Application number: PCT/DK2002/000550
Authority: WO
Inventors: Jesper Helveg Thomsen; Johnny Varnke Pedersen
Original assignee: Inter Primo A/S
Priority date: 2001-08-22
Filing date: 2002-08-21
Publication date: 2003-03-06
Also published as: EP1430494B1; DE60202628D1; DE60202628T2; ATE287122T1; EP1430494A1

Abstract

The present invention discloses a tape or ribbon switch component (1) comprising a pair of electrical contact strips (5, 6) made from a non corrosive material and encapsulated in a moisture impermeable cover (2) comprising as an integral part hereof spacer means (4) providing the appropriate distance between said contact strips (5, 6). The invention furthermore discloses a tape or ribbon switch based on this component and an in-situ tailoring method for fitting the tape or ribbon switch to a specific application, where said method provides for a hermetically seal of the ends of the switch against moisture penetration from outside. Specifically said seal is provided by the use of heat crimping terminating means (8), the inner surface of which are provided with an adhesive agent, whereby it is made possible by the application of a heat crimping tool to obtain said hermetical sealing of the tape or ribbon switch.

Description

TAPE OR RIBBON SWITCH

TECHNICAL FIELD

The present invention relates to tape or ribbon switches and more particularly to such switches designed to be attached to gates, doors etc. as part of security systems as set forth in the preamble of claim 1. The invention furthermore relates to a manufacturing process for such switches and to an in-situ tailoring method to be used to fit the switch to a specific application.

DESCRIPTION OF PRIOR ART

Various types of tape- or ribbon switches have been known within the art for many years. Thus US 2,770,696 discloses a tape switch comprising a one-piece outer jacket preferably made of a rubber or plastics material, which tape switch can also be sued outdoors. Within said outer jacket there is contained two juxtaposed substantially plane contact strips separated from each other by means of strips of insulating material placed between the contact strips along the outer edges thereof.

US 4,293,752 discloses a self adhering tape switch the outer shape of the cover somewhat resembling that of the present invention, but as in the above mentioned case also provided with strips of insulating material placed between the contact strips along the outer edges of these for separation of the contact strips.

In US 4,551 ,595 the outer cover is not formed as a one-piece unit but rather welded together comprising separate top- and bottom portions. Also in this case strips of insulating material are placed between the contact strips along the outer edges of these for separation of the contact strips.

Neither of the above references discloses specific methods recommended for in-situ tailoring the switches to specific applications.

Prior art tape- or ribbon switches have typically suffered from a number of problems. One of these problems have been penetration of moisture through the outer insulating cover of the switch due for instance to the application of a hygroscopic (water- absorbing) material for the cover or to improper or unreliable tailoring of the switch during the specific application hereof. The penetration of water through the outer cover and into the contact region of the switch have often led to corrosion of the electrical contact surfaces in cases where the contacts have for instance been made of copper, leading to an unreliable electrical contact and hence possibly to dangerous situations, if the switch has formed part of a security system, for instance in connection with a heavy gate.

SUMMARY OF THE INVENTION

According to the preceding description of some prior art problems it is thus an object of the present invention to provide an improved tape switch component that does not suffer from the above problems of moisture penetration through the outer cover of the switch and into the contact region of the switch.

It is a further object of the present invention to provide a tape switch component that can be manufactured in a simple manner.

It is a further object of the present invention to provide a tape switch comprising said tape switch component and appropriate terminating means so that said tape switch does not suffer from the above problems of moisture penetration through the terminating means (electrical leads to the contact strips of the tape switch and electrical terminating impedance) and into the interior of the tape switch.

It is a further object of the present invention to provide an improved method and system for in-situ tailoring of the switch to various specific applications.

These and other objects are attained with a tape switch component according to claim 1 , a tape switch according to claim 5 and an in-situ tailoring method according to claim 10.

According to a first aspect of the present invention there is thus provided a tape switch component comprising a pair of parallel extending contact strips one of which is provided with a laterally extending corrugation in order to improve mechanical stability, said contact strips being completely surrounded by an outer cover to electrically isolate the contact strips from the surroundings and furthermore to prevent moisture from reaching the contact strips. The contact strips are held apart by suitable spacer means extending longitudinally over a portion of the surfaces of the contact strips facing one another, which spacer means according to the invention are formed as an integral part of said outer cover to provide a reliable spacing of the contact strips and furthermore to provide a simple and effective manufacturing process of the tape switch. In order to prevent moisture from penetrating the outer cover and reach the contact strips resulting in corrosion of these the outer cover is made of a water-impermeable (hygroscopic) material of suitable mechanical flexibility. In order to ensure reliable contact function throughout the life of the tape switch the contact strips are made from a material that is resistant against corrosion and that is not attacked by cleaning agents, oils etc. used in industries. In a preferred embodiment of the invention the contact strips are made of stainless steel.

A manufacturing process for said tape switch comprising component comprises the steps of providing two ribbons of metal sheets and passing one of said ribbons through a corrugation machine to provide said ribbon with a pattern of corrugations substantially lateral relative to the longitudinal extension of the ribbon and feeding said two ribbons into a torpedo provided in a transversal extruder head provided with an inlet for a melted plastics material supplied by an extruder. At the outlet of the torpedo the melted plastics material is joined with the metal ribbons and passed through a nozzle section to provide the desired cross section of the tape switch including the spacer means provided between the two metal ribbons as mentioned in the preceding paragraph. On leaving the transversal extruder head the tape switch finally passes through a water bath, whereby the temperature of the switch is reduced from its manufacturing temperature (for instance around 160 degrees centigrade) to room temperature. The fact that said spacer means are formed as integral parts of the outer cover provides for a very simple and straight forward manufacturing process.

According to a second aspect of the present invention there is thus provided a tape switch comprising a suitable length of said tape switch component and furthermore provided with suitable terminating means. One end of the cut off tape switch component is thus provided with electrical contact leads to establish electrical contact to the two contact strips of the tape switch and the electrical leads and a suitable length of the tape switch component is surrounded by a body of heat shrinking foil, the inner surface of which is provided with an adhesive agent that when initially heated and subsequently cooled down to ambient temperature adheres firmly to the outer surface of said outer cover of the tape switch and to the outer surface of terminal lead electrically connected to the contact strips of the switch. The other end of the cut off tape switch component is sealed in a similar manner and may instead of said electrical leads be provided with an electrical terminating impedance component, such as a resistor of suitable electrical resistance. The end could also be left electrically open if desired for specific applications.

According to a third aspect of the present invention there is provided an in-situ tailoring method for said tape switch, said tailoring method comprising the following main steps:

Providing an appropriate length of tape switch according to the specific application;

Providing a first contact plate provided with electrical contact leads to establish electrical contact to the two contact strips of the tape switch;

Insertion of said contact plate provided with electrical contact leads into a first end of the switch into the region between the two contact strips;

Providing a tubular body of heat shrinking foil, the inner surface of said body being provided with an adhesive agent that when initially heated and subsequently cooled down to ambient temperature adheres firmly to the outer surface of said outer cover of the tape switch and to the outer surface of terminal leads etc. electrically connected to the contact strips of the switch;

Pushing said body of heat shrinking foil over said first end in such a manner that said body covers both an appropriate length of the tape switch and an appropriate length of said electrical contact leads;

Providing heat for instance by means of an appropriate shrinking tool to said tubular body thereby melting the glue provided on the inside of said tube and shrinking the tube until a tight seal is established between the tape switch and the tubular body and between the tubular body and the contact leads respectively;

Providing a second contact plate provided with an electrical component for providing an appropriate electrical terminating impedance between the two contact strips of the tape switch; Insertion of said second contact plate into a second end of the switch into the region between the two contact strips;

Providing a tubular body of heat shrinking foil, the inner surface of said body being provided with an adhesive agent that when initially heated and subsequently cooled down to ambient temperature adheres firmly to the outer surface of said outer cover of the tape switch and also covers and provides a tight seal around said second contact plate and said terminating impedance component.

Providing heat for instance by means of an appropriate shrinking tool to said tubular body until a tight seal is established between the tape switch and the tubular body and around said second contact plate with said terminating impedance component;

The claimed tape switch component and corresponding tape switch adapted to specific applications using said tailoring method offers the advantageous effects of highly reduced humidity intrusion through the outer cover and the end portions of the switch. An error free operation is furthermore ascertained by the choice of contact material of stainless steel. The described in-situ tailoring method and a corresponding system comprising the necessary components and tool's provide for an easy and reliable fitting of the switch for the specific application. Furthermore the switch is characterised by a lack of deformation by bending up to 90 degrees and by a small activation force of approximately 3N.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to the accompanying drawings, in which

Figure 1 a is a perspective view of the tape switch component according to the invention;

Figure 1b is a cross-sectional view of the tape switch component shown in figure 1a;

Figure 2 is a schematic representation of a tape switch based on the tape switch component shown in figure 1 a and 1 b; and Figure 3a and 3b is a schematic representation of in-situ tailoring of a tape switch according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following a detailed description of the invention is given.

With reference to figure 1a and 1b there is shown a tape switch component according to the invention generally referred to by reference numeral 1. The tape switch component comprises two juxtaposed electrical contact strips 5, 6 of which one in the present embodiment of the invention is provided with a laterally oriented corrugation provided in order to increase mechanical stability of the switch. According to this specific embodiment of the invention the contract strips 5, 6 are made of thin sheets of stainless steel, which is considerably more resistant to oxidation than other materials normally used in such switches such as copper. According to this specific embodiment of the invention the upper contact strip has a thickness of 0,05 mm and the lower contact strip 0,1 mm, although it is understood that other choices of thickness of the contact strips could also be made.

Surrounding and tightly encapsulating said contact strips there is provided an outer cover 2 formed as one longitudinally extending piece by means of a suitable extrusion process. The cover 2 is provided with an outwardly extending longitudinal protrusion 3 provided in order to ensure a reliable contact action of the switch, when this is exposed to an external pressure, and two internal longitudinally extending thin protrusions 4 acting as spacer means between the two contact strips 5, 6. Formation of these spacer means 4 as an integral part of the outer cover 2 is advantageous both from a manufacturing and a reliability point of view.

With reference to figure 2 there is shown a tape switch comprising a suitable length of the tape switch component 1 described above and furthermore comprising terminating means 8, 9 at either end of the tape switch component. As described in the summary of the invention - and in detail in the subsequent section on in-situ tailoring of the switch - these terminating means 8, 9 are formed by pieces of heat shrinking foil, the inner surfaces of which are provided with an adhesive agent which heat shrinking foil and adhesive agent upon heating and subsequent cooling to ambient temperature forms a tight seal around the ends of the tape switch component 1. The terminating means 8 comprises an electrical lead 10 broad in contact with the contact strips 5, 6 in the tape switch component for instance by the method described in the following. Similarly the other terminating means 9 may comprise an electrical terminating impedance element, such as a resistor, although an open ended electrical termination could also be conceived (i.e. infinite impedance).

With reference to figure 3a and 3b there is very schematically shown the main steps to be performed during tailoring of the tape switch according to the invention for a specific application. These steps comprises:

(a) Provision of an appropriate length of the tape switch component 1 ;

(b) Removal of an appropriate length (for instance 10-mm) of the protrusion 3 from a first end of the tape switch component 1 ;

(c) Pushing a tongue-formed contact plate 11 made from a dielectric material and provided with upper and lower layers 12, 13 of an electrically conducting material, where the two electrical conductors 10' and 10" of an electrical lead 10 are conductively connected (for instance by soldering) to each of said layers 12, 13 respectively, into the switch in the region 7 between the two contact strips 5, 6 of the switch;

(d) Pushing a heat shrinking foil tube 8' over the end of the switch component 1 until contact with the protrusion 3;

(e) Providing heat by means of an appropriate shrinking tool to said tube 8' (this process not shown in the figure) thereby melting the adhesive agent provided on the inside of said tube 8' and shrinking the tube 8', until a tight seal is established between the switch 1/the lead 10 and the tube 8';

(f) Removal of an appropriate length (for instance 10-mm) from the second - non- tailored - end of the tape switch component 1 ;

(g) Pushing a tongue-formed contact plate 14 made from a dielectric material and provided with upper and lower layers 15, 16 of an electrically conducting material, between which layers 12, 13 there is electrically connected an appropriate electrical impedance element 17, such as a resistor, into the switch component 1 in the region 7 between and around the two contact strips 5, 6 of the switch;

(h) Squeezing the end of the heat shrinking foil tube 9' together (for instance by means the metal clamp or similar tool, not shown in the figure) and pushing the heat shrinking foil tube 9' over the second end of the tape switch component 1 until contact with the protrusion 3 on the tape switch component 1 ;

(i) Providing heat by means of an appropriate shrinking tool to said tube 9' (this process not shown in the figure) thereby melting the adhesive agent provided on the inside of said tube 9' and shrinking the tube 9', until a tight seal is established between and around the switch 1/the impedance element 17 and the tube 9';

G) After appropriate cooling of the heat shrinking foil tube 9' removal of the clamp herefrom;

Although various embodiments of the present invention have been shown and described in the preceding parts of the detailed description it is understood that a person skilled in the art may conceive other embodiments of the invention without departing from the scope of the invention as defined by the following claims.

Claims

CLAIMS:

1. A tape switch component comprising two longitudinally extending juxtaposed electrical contact strips surrounded by an outer cover, characterised in that said cover (2) is formed as one piece comprising spacer means (4) to establish a predetermined gab (7) between said two contact strips (5,6).

2. A tape switch component according to claim 1 , characterised in that said contact strips (5,6) are made of an electrically conducting material which is environmentally resistant.

3. A tape switch component according to claim 2, characterised in that said electrically conducting material is stainless steel.

4. A tape switch component according to any of the preceding claims, characterised in that one of said contact strips (5,6) is corrugated in a substantially lateral direction of the longitudinally extending contact strips (5,6).

5. A tape switch comprising a tape switch component according to any of the preceding claims, characterised in that a first and second longitudinal end of said tape switch component is provided with first and second sealing means (8,9).

6. A tape switch according to claim 5, characterised in that said sealing means (8,9) are formed by means of a heat shrinking foil (8', 9').

7. A tape switch according to claim 6, characterised in that said heat shrinking foil (8', 9') on the inner circumferential surface hereof is provided with an adhesive agent.

8. A tape switch according to claim 5, characterised in that said first terminal means (8) comprises first contact means (11, 12, 13) for providing electrical contact between each of the two contact strips (5, 6) and corresponding electrical conductors (10', 10") in an electrical lead (10).

9. A tape switch according to claim 8, characterised in that said first contact means comprises a substantially flat plate (11 ) of dielectric material on opposing sides provided with electrically conductive layers (12, 13), where said conductors (10', 10") are connected to each of said layers (12, 13) respectively.

10. A tape switch according to claim 5, characterised in that said second terminal means (9) comprises second contact means (14, 15, 16) for providing electrical contact between each of the two contact strips (5, 6) and an electrical impedance element (17) provided between said contact strips (5, 6).

11. A tape switch according to claim 10, characterised in that said second contact means comprises a substantially flat plate (14) of dielectric material on opposing sides provided with electrically conductive layers (15, 16).

12. A tape switch according to claim 10, characterised in that said electrical impedance element (17) is a resistor.

13. A method of tailoring a tape switch according to claim 6 or 7, characterised in that said first and second longitudinal end of said tape switch component (1) is sealed by application of a heat shrinking process to said first and second sealing means (8,9).

14. A method of tailoring a tape switch according to any preceding claim, characterised in that said method comprises the following steps:

(a) Provision of an appropriate length of the tape switch component 1 ;

(c) Pushing a tongue-formed contact plate 11 made from a dielectric material and provided with upper and lower layers 12, 13 of an electrically conducting material, where the two electrical conductors 10' and 10" of an electrical lead 10 are conductively connected (for instance by soldering) to each of said layers 12, 13 respectively, into the switch in the region 7 between the two contact strips 5, 6 of the switch; (d) Pushing a heat shrinking foil tube 8' over the end of the switch component 1 until contact with the protrusion 3;

(j) After appropriate cooling of the heat shrinking foil tube 9' removal of the clamp herefrom;