GB2194102A - Sheet circuit - Google Patents

Abstract

in a sheet circuit, conductor strip sheets (1, 3) are spaced apart by a spacer sheet (5). In order to integrate an adjustable resistance into the sheet circuit, a conductor strip (4) is provided on the one conductor strip sheet (3) and, opposite to this strip, a resistance strip (2) is provided on the other conductor strip sheet (1). A presser element (24), slidable longitudinally of the conductor and resistance strips (2, 4), is provided on the sheet circuit, which presser element presses a portion of the conductor or resistance strip (2, 4) respectively onto the other strip, the position (17) of the portion travelling along the strips (5, 6) during displacement of the presser element. <IMAGE>

Description

SPECIFICATION Sheet circuit This invention relates to a sheet circuit comprising adjustable resistance and conductor strip sheets, which are spaced apart by a spacer sheet.

Such sheet circuits include, for example, sheet keyboards having a plurality of switching chambers. Above the switching chambers, keys are disposed for actuating contact points. If, in such sheet circuits, a manually adjustable resistance is required in addition to the switching contacts actuated by keys, then a separate resistance component is connected with the sheet circuit.

The object of the present invention is to provide a sheet circuit as initially mentioned, in which the adjustable resistance is an integral component of the sheet circuit.

According to the invention there is provided a sheet circuit in which a conductor strip is provided on one conductor strip sheet and, at a distance from and opposite this, a resistance strip is provided on the other conductor strip sheet, a presser element displaceable in the longitudinal direction of the conductor and resistance strips is mounted on the sheet circuit, which presser element presses a portion of the conductor or resistance strip respectively onto the other strip, the position of this portion travelling along the strips during the displacement.

The conductor strip and the resistance strip are located freely opposite each other, without a spacer sheet between. The strips are so pressed at a position onto one another by the presser element that they contact each other.

The sheet circuit therefore comprises an adjustable resistance as an integral component.

The resistance may also be connected as a potentiometer. Additional electrical connecting means between the- adjustable resistance and the other conductor strips of the conductor strip sheets thereby become unnecessary. The resistance strip can be printed by printing technique onto the corresponding conductor strip sheet. The opposite conductor strip of the other conductor strip sheet can be applied together with its other conductor strips.

Due to the flexible elasticity of the conductor strip sheets, the presser element causes the two strips to contact each other at the position intended for contacting, without special measures.

In a preferred embodiment of the invention, a slider is provided, which is displaceable together with the presser element along the conductor strip, lies between the base sheet and the upper sheet, keeps the strips apart adjacent to the presser element and has an opening, through which the presser element presses the one strip onto the other.

Preferably, a guide slit is provided adjacent to at least one longitudinal edge of the conductor and/or resistance strips on at least one conductor strip sheet, an edge of the slider being slidably guided in this slit. As a result, an especially simple mounting of the slider on the sheet circuit and a reliable relationship between the presser element and the strips are obtained.

In order to ensure that the position, at which the conductor strip and the resistance strip touch each other under the action of the presser element, shall be as limited and welldefined as possible, in a preferred embodiment of the invention the slider, formed of a frame, possesses spacer webs adjacent to the presser element and spaced apart longitudinally of the strips, these webs extending between the two conductor strip sheets. The spacer webs ensure the necessary spacing between the two strips on either side of the contact position.

A manually actuatable operating component may be fitted to the slider.

Embodiments of the invention will now be described by way of example with reference to the accompany drawings in which: Figure 1 is a part plan of a sheet circuit according to the invention, Figure 2 is a section along the line Il-Il in Figure 1, Figure 3 is a plan on the base sheet with resistance coating, Figure 4 is a view of the lower face of the cover sheet with silver strip, Figure 5 is a view of an insulating intermediate layer, as a slider for the sheet circuit according to Figure 1, Figure 6 is a part view of a further sheet circuit according to the invention, Figure 7 is a section along the line VII-VII of Figure 6, Figure 8 is a section along the line IIX-IIX of Figure 7, Figure 9 shows the slider shown in Figures 7 and 8 before mounting on the sheet circuit, Figure 10 is a sectional elevation through the slider of Figure 8 along the line X-X of Figure 9, Figure 11 is a further example of embodiment of a slider in a view corresponding to Figure 8, Figure 12 shows the slider of Figure 11 shown separately, Figure 13 is a further example of embodiment of a slider in a view corresponding to Figure 7 along the line XIII-XIII of Figure 14 and Figure 14 is a section along the line XIV XIV of Figure 13.

Referring to Figures 1 to 5 a sheet circuit includes a potentiometer comprising a stripshaped resistance layer 2 situated on a base sheet 1 of the sheet circuit, a conductor strip 4 of silver on a cover sheet 3 of the sheet circuit, and an insulating intermediate layer 8, displaceably located between the base sheet 1 and the cover sheet 3 and having an opening 9. Two supply conductors 10 and 11, which terminate on a contact tongue 12, lead to the resistance layer 2. The silver strip 4 lies over the resistance layer 2 and is connected with a supply conductor 15, which leads to a contact tongue 16. Between resistance layer 2 and silver strip 4 is the insulating intermediate layer 8 constituting a slider, the opening 9 in which makes possible a contact between the silver strip 4 and the resistance layer 2.The insulating intermediate layer 8 is connected by two studs 20 and 21 with a spring arm 22 of an actuating slider 23. At the free end of the spring arm- 22 a cam or presser element 24 is mounted as a presser element, which bears against the cover sheet 3 in the region of the silver strip 4 and presses this strip through the opening 9 to make contact with the resistance layer 2. A baseplate 26, carrying the base sheet 1, continues beyond the sheet 1 and possesses a slit 27 for a guide member 28, to which an operating button 30 is fixed.

The guide member 28 has-a shoulder 31 and a support 32 for the spring arm 22 for the slidable mounting of the guide member 28 on the baseplate 26.

If the actuating slider 23 is displaced by means of the operating button 30, then the presser element 24 slides along the cover sheet 3 above the silver strip 4 and presses this strip through the opening 9 of the insulating intermediate layer 8 onto the resistance coating 2 during its displacement travel until the actuating slider 23 has reached the desired position. The silver strip 4, at the position where the cam 24 and thus also the opening 9 of the insulating intermediate layer 8 8 are situated, is therefore in contact with the resistance layer 2, so that different resistance and voltage values can be set. Only one contact position is present therefore for tapping the various values, at the position where the silver strip 4 and resistance layer 2 are in contact with each other.

A sheet circuit according to Figure 6 also possesses a cover sheet 3 and base sheet 1.

Both the sheets are printed with conductor strips, which are spaced apart by a spacer sheet 5. In the region of switching chambers 6, the conductor strips are located freely op posite each other. The cover sheet 3 is printed, at one edge, with an additional conductor strip 4. The base sheet 1 is printed, opposite the conductor strip 4, with a resistance strip 2. The strips 2, 4 are of approxi mately equal length and width. They are positioned freely opposite each other. The electrical connections for the strips 2, 4 are provided at their narrow ends.

The conductor strip sheets 1, 3 are provided with two continuous slits 7, 7'. The slits 7, 7' extend parallel to and alongside the strips 4, 2. Adjacent to the slit 7 a spacer band 29 is glued between the cover sheet 3 and the base sheet 1, this spacer band being thicker than the spacer sheet 5. As a result, the distance between the sheets 4, 2 is increased (see Figure 7).

A slider 8 according to Figure 9 consists of a rectangular plastics frame, having edge strips 8', 8" and spacer webs 13, 14. On the edge strips 8', 8", centrally between the spacer webs 13, 14, presser elements 24, 25 are constructed as resiliently elastic arms.

When not inserted into the sheet circuit, the presser elements 24, 25 bear against each other as shown in Figure 10.

The slider 8 is so inserted into the sheet circuit that its edge strips 8', 8" lie in the slit 7, 7' respectively and the spacer webs 13, 14 extend between the strips 4, 2. The presser element 24 presses onto the cover sheet 3 and the presser element 25 presses onto the base sheet 1. As a consequence, the strips 4, 2 contact each other at a position 17 (see Figures 7 and 8). As the presser elements 15, 16 act on both sides, the two conductor strip sheets 1, 2 are bent towards each other until their strips 4, 2 touch each other. The spacer webs 13, 14 ensure that the contact between the strips 5, 6 is limited to the desired position 17.

If the slider 8 is now displaced in the longitudinal direction of the strips 4, 2, by means of an actuating element (not shown) then it is guided by means of its edge strips 8', 8" in the slits 7, 7'. During the displacement, the position 17 correspondingly follows the movement, so that the conductor strip 4 taps a correspondingly different resistance value at the resistance strip 2.

The slider 8 according to Figure 12 possesses, in contrast to the slider 8 of Figure 9, only one single presser element, namely 24; in other respects it is the same as the slider 8 of Figure 9.

In Figure 11, the slider 8 of Figure 12 is shown in its installed position. The presser element 24 presses only onto the base sheet 1. It presses its resistance strip 2 onto the conductor strip 4 of the upper conductor strip sheet 1, which is not bent or deflected but can be supported. The bending of the lower conductor strip sheet 1 is correspondingly larger than that of Figure 8. The presser element 24 has a correspondingly stiff spring characteristic.

The slider 8 according to Figures 13 and 14 consists of an upper part 18 and a lower part 19. These two parts 18, 19 are connected together by a plastics hinge strip 33, formed in one piece with these two parts. At the side remote from the hinge strip 33, the upper part 18 possesses an edge strip 34 and the lower part 19 an edge strip 35, which can be secured to each other, for example by a snap connection.

On the upper part 18, a presser element 24 is formed. On the lower part 19, spacer webs 13, 14 are provided, which extend between the base sheet 1 and cover sheet 3. The lower part 19 supports the base sheet 1 beneath the presser element 24, so that only the cover sheet 3 is bent or deflected by the presser element 24.

Numerous further examples of embodiment lie within the scope of the present invention.

Thus, for example, it is possible, in the example of the embodiment according to Figures 11 and 12, so to arrange the presser element 24 that it deforms the conductor strip 4 and not the resistance strip 2. The slit 7' may also be omitted. The slider 8 is then introduced directly from the edge of the sheet circuit and bears against this edge. The individual measures of the various Figures may also be combined with one another.

If the sheets 1, 3 are sufficiently stiff-flexible, the insulating intermediate layer 8 may also be secured between the two sheets, for example glued. Its opening 9 is then formed as a slit, extending along the strips 2, 4. In this case, a slider 8 is unnecessary.

The strips 2, 4 do not need to be rectilinear as shown in the Figures. They may also be curved. If they run along a circular arc, then instead of the sliding potentiometer shown, a rotary potentiometer is created. Instead of the slit 27 of Figure 1, a rotary bearing for the spring arm 22 can then be provided.

Two resistance strips may also be arranged in parallel relationship alongside each other. A tandem operation is then possible. In this case, each resistance strip has its own presser element. The resistance strip may also possess a non-linear characteristic of its resistance value.

The potentiometer may be provided not only in those sheet circuits which are pure keyboards. The sheet circuit may also possess printed inductance and/or printed capacitors of passive networks.

Claims (18)

1. A sheet circuit comprising first and second sheets which are spaced apart by a spacer sheet, a conductor strip provided on a first, conductor strip sheet, a resistance strip provided on the second, resistance strip sheet and opposing said conductor strip, a presser element mounted on the sheet circuit and displaceable in the longitudinal direction of the conductor and resistance strips which presser element presses together the-conductor strip and resistance strip so that they contact at a position determined by the location of the presser element, this contact position travelling along the strips during displacement of the presser element.

2. A sheet circuit according to claim 1, comprising a slider displaceable with the presser element along the strips, which slider is arranged between the first and second sheets and keeps the strips apart adjacent to the presser element and which possesses an opening, through which the presser element presses one of the strips onto the other.

3. A sheet circuit according to claim 2, in which the slider is formed of an insulating intermediate layer which extends between the strips to keep them apart and possesses an opening in the region where the presser element presses together the strips.

4. A sheet circuit according to claim 2 or 3, in which an actuating member actuates the slider and presser element respectively.

5. A sheet circuit according to preceding claim 4, in which the actuating member is guided in a slit of a baseplate carrying one of said first and second sheets which functions as a base sheet.

6. A sheet circuit according to claim 4 or 5, in which the actuating member comprises a spring arm, to the free end of which is fixed a presser element.

7. A sheet circuit according to claim 4, 5 or 6, in which the actuating member comprises an operating button, a guide piece which extends through a slit in a baseplate or a housing, and a support for the spring arm situated beneath the baseplate or housing.

8. A sheet circuit according to any one of claims 2 to 7, in which adjacent to at least one longitudinal edge of the conductor and/or resistance strip on at least one sheet, there is provided a guide slit, in which an edge strip of the slider is slidably guided.

9. A sheet circuit according to any one of claims 2 to 8, in which the slider possesses at least one web, which bears against a side of one or each sheet remote from the presser element and, together with the presser element, bends one or each sheet.

10. A sheet circuit according to claim 6 or any one of claims 7, 8 or 9 as dependent upon claim 6, in which the slider possesses, adjacent to the presser element, spacer webs which are spaced apart longitudinally of the strips, and extend between said first and second sheets.

11. A sheet circuit according to claim 6 or any one of claims 7 to 10 as dependent upon claim 6, in which the slider comprises a second presser element, opposing the first-mentioned presser element, such that the two presser elements bend or deform the two sheets and press the conductor strip and the resistance strip together at the position between the two presser elements.

12. A sheet circuit according to claim 6 or any one of claims 7 to 11 as dependent upon claim 6, in which the slider is formed of a single-piece plastics frame, on which the presser element or presser elements are formed as resilient elastic arms.

13. A sheet circuit according to claim 12, in which the plastics frame forms edge strips for guiding the slider and spacer webs.

14. A sheet circuit according to claim 6 or any one of claims 7 to 13 as dependent upon claim 6, in which the slider consists of an upper part and a lower part, and that the presser element for the one sheet is formed on the upper part and the lower part supports the other sheet.

15. A sheet circuit according to claim 14, as dependent upon claim 8 in which the upper part and the lower part are connected at one side by a hinge and are secured together at the opposite side by means of edge strips which lie in the slit of the or each sheet.

16. A sheet circuit according to any one of the preceding claims, in which a spacer band or layer is laid alongside and substantially par allel to the strips between the sheets, which band or layer is thicker than the spacer sheet.

17. A sheet circuit according to claim 2 or any one of claims 3 to 16 as dependent upon claim 2, in which the slider is an insulating intermediate layer and is secured between the sheets and its opening is formed as a slit extending longitudinally of the strips, through which slit the presser element or elements presses the one strip onto the other strip.

18. A sheet circuit substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.