SE502098C2 - Piezoelectric switching matrix - Google Patents

Abstract

A switching matrix includes at least one array (22) of piezoelectric relays having cantilevered drive elements (24) which preferably are in the form of a unitary, comb-shaped structure of piezoceramic material. Each drive element carries adjacent its free end at least one movable contact (50,52) such as a single or double bridge, for engagement with one or more fixed contacts (56,58) in either single or double throw fashion. The fixed contacts may be mounted on housing walls enclosing the relay array or on a separate substrate also mounting the drive element unitary structure. Row (R) and column (C) conductors or conductor pairs are connected into the relay contacts by non-intersecting conductor runs printed on the surfaces of the housing walls or on the substrate. <IMAGE>

Description

sozfoøs burned into various desired shapes, for example rectangular shaped, thin plates. Piezoelectric relays require very low impact power, diverts minimal power too holding an affected condition without external assistance and does not draw current while in their rest position stand. Consequently, piezoelectric relays generate a lot little heat. They can be made in smaller physical sizes than comparable electromagnetic relays and requires fewer, much simpler components. The piezoelectric drive elements its electrical properties are fundamentally capacitive to its nature and is thus different from electromagnetic tical relays immune to magnetic leakage fields.

A main object of the present invention is to provide an improved switching matrix. This must have special but limited application in the field of telecommunications. The shall use piezoelectric switch actuating elements.

Another object is to provide a piezoelectric switch. matrix relay with a set of piezoelectric relays, which are efficiently arranged in a compact matrix assembly.

The piezoelectric switching matrix relay shall be capable of manufactured in batches using methods of management drawing by means of printed circuits. At the piezoelectric the switching matrix relay, the wiring shall be by means of printed circuits for the switching points of the matrix can achieved without line crossovers. A minimum number switching connections shall be required. The piezoelectric The switching matrix relay shall be of efficient design tion, easy to manufacture, of compact size and be reliable for a long service life.

Examples of the state of the art can be found in JP 52-60005 OCh AU, B, 273 157.

Essential features of the invention are set forth in the claims 1 characteristic part. , §So2 us A piezoelectric switching matrix according to the invention can in practice include a flat set of individual effective bimorph driving elements, which are generally load-bearing means are mounted in a house. Next to each drive ments free end, at least one movable contact is balanced with a gap to at least one associated solid connector, which is mounted on a wall of the house or a support elements, which jointly carry the drive elements. Then selected drive elements are electrically activated, these are deflected, so that their movable contacts are brought into electrical contact with associated fixed contacts. The switching motion can be single or double. In the latter case, each driver is arranged to be selectively deflected in opposite directions, so that it comes into contact with either of a couple of hearing fixed contacts. Each movable contact can have the shape of a short-circuit rail, which is arranged to be able to come to touch with a pair of adjacent fasteners contacts. When wiring the switching matrix its row and column conductors are connected to the opposite surfaces of the mounting elements for the fixed contacts as at printed circuits, with suitable electrical connections made to the various relay contacts. The one of several levels permanent, planar arrangement of these conductor lines is such that line crossovers are eliminated, which is why layer printing methods do not need to be applied.

For a better understanding of the nature of and the purposes of present invention, this is described in detail therein the following with reference to the accompanying drawings, i which: 502 098 f Fig. 1 is a plan view, partly in schematic form a piezoelectric switching matrix relay, which is constructed in accordance with an embodiment of the present invention invention, Fig. 2 is a side view of the switching matrix of Fig. 1, Fig. 3 is a plan view, partly diagrammatically showing one piezoelectric switching matrix relay according to an alternative embodiment of the invention, Fig. 4 is a partial side view of the switching matrix according to Fig. 3, Fig. 5 is a plan view, partly diagrammatically showing one piezoelectric matrix switching relay according to further an embodiment of the invention, Fig. 6 is a partial side view of the switching matrix according to Fig. 5, and Fig. 7 is a partial perspective view of the movable contact end of a bimorph drive element, which is useful for the switching matrix embodiments of Figs. 3 and 5.

Equal reference numerals refer to corresponding parts in the different drawing views.

In the embodiment of Figs. The invention comprises a piezoelectric switching circuit. matrix relay 20 a planar, uniform set 22 of indi- vidual bimorph drive elements 24. The drive element set is preferably of a shape similar to a comb with a centrally located spine 26, the individual the drive elements extend distributed and parallel with each other from both sides of the spine on cam-like way. As shown in Fig. 2, drive elements are 5o2; 09s 22 fixedly mounted along its spine 26 on top of one plinth 28, which is carried in a housing 30. It is thus clear that the individual bimorph drive elements 24 are mounted in a cantilevered manner with their free ends similar to formally distributed between an upper housing wall 32 and a 'lower housing wall 34. Each drive element consists of one pair piezoelectric plates 36 and 38, which are bonded together in sandwich mold with a common, intermediate surface electrode 40. This intermediate electrode may be common to all drive elements 24. The top 36 of the plate 36 is exposed surface is coated with a conductive metal, so that an electrode 42 is obtained, while the exposed lower surface of the plate 38 is on similarly made to electrode as indicated at 44.

The plates are formed of a known piezoceramic material, for example, lead zirconate titanate (PZT), while the surface electrodes are provided with deposited coatings of a suitable metal, such as nickel, silver and the like.

As schematically shown in Fig. 2, an integrated circuit package 46 is mounted on top of the spine 24, separate conductors are connected to the various electrodes 40, 42 and 44 of each of the drive elements 24. In response on selection signals, this integrated circuit applies a activating voltage across one or the other of the piezoceramic plates 36, 38 of a selected one selected number of drive elements to achieve this or these are deflected, either upwards as indicated by the arrow 48a or down as indicated by arrow 48b. The mechanisms which causes deflections of a cantilever mounted, piezoceramic, bimorph bending element, for example the drive elements 24, are well known in the art.

Adjacent to the free end of each drive element, see Fig. 2, is mounted a pair of opposite, movable contacts 50 and 52, joint electrically connected by a connecting pin 54. On the underside of the upper wall 32 of the housing is a separate, fixed contact 56 opposite and with gap to each 502 098? of the upper movable contacts 50, while a separate, fixed contact 58 is mounted to the lower wall 34 of the housing opposite and with gaps to each moving con- rate 52. Thus, a selected drive element 24 is deflected upwards, its movable contact 50 comes into contact with opposite fixed contact 56, and then a selected one drive element deflected downwards, its movable contact will 52 to contact with opposing fixed contact 58. Be- the movement between the contacts is maintained for as long as one Of the piezoceramic plates 36, 38 charged condition is maintained. In its non-activated hibernation state the drive elements the positions shown in Fig. 2, the tubular contacts 50 and 52 are substantially uniform gap to the fixed contacts 56 resp. 58. It is so- it is clear that each drive element 24 together with the movable contacts 50, 52 and fixed contacts 56, 58 forms a piezoelectric single-pole dual-position relay.

The wiring for the fixed and movable contacts in the switching matrix 20 to provide a 6 x 6- matrix using eighteen double-position (with deflection up and down) drive element 24 is shown in Fig. 1.

The reference numerals R1 to R6 indicate what can considered as six line guides, and reference numerals C1 to C6 indicate six column conductors. As shown in As shown in Fig. 2, the column conductors C1, C2 and C3 are printed circuit conductor lines, which are arranged on the upper surface of the wall 34 to the left of the base 26 while The column conductors C4, C5 and C6 consist of printed circuit boards. conductor stretches, which are arranged on the upper wall 34 surface to the right of the base. These column leaders represent dotted lines in Fig. 1. It is thus clearly, that the column conductor C1 via free-hanging conductor 60 is connected to the movable contacts 50 and 52 of the three lower drive elements 24. The column conductor C2 is further via free-hanging conductors connected to the moving ones the contacts of the three intermediate drive elements, which stretch 502 usa lr to the left of the spine 26, and the column leader C3 is connected to the upper left three drive elements moving contacts. Column leaders C4, CS and C6 are used closed to the movable of the three upper right drive elements contacts, the tubes of the three middle right drive elements league contacts resp. the three lower right drive elements 24 movable contacts, as can be seen from Fig. 1.

The solid lines showed the line guides R2, R4 and R6 ~ are arranged as printed circuit conductor lines, which laid out in a serpentine-like manner on the upper wall of the house 32 upper or outer surface. As will be appreciated, these three conductors are pressed onto the inner surface of the housing wall 32. Those with dashed lines showed the line guides R1, R3 and R5 are printed on the lower or outer surface of the housing wall 34 on the pentine-like manner. As shown, the line conductor R1 is via pins 59a extending through holes in the housing wall 34, connected to the fixed connectors 58, which are connected with the first, sixth and seventh left and right drivers the elements 24, the counting taking place from below in Fig. 1.

The line conductor R2 is via pins 59b, which pass through housing the wall 32, connected to the fixed contacts 56, which also are associated with the first, sixth and seventh opposite pairs of those in opposite directions stretching drive elements. Similarly, the line conductors R3 and R4 connected to the fixed contacts 58 resp. 56, som are associated with the second, fifth and eighth opposites the pairs of drive elements 24, while the row conductors R5 and R6 are connected to the fixed contacts 58 resp. 56, which is connected with the third, fourth and ninth opposites the pair of drive elements. The house wall 32 carries a first number connections 55 for making electrical contact with the fixed contacts 56, while the housing wall 34 carries a second number of connections 57 for providing electrical contact with the fixed contacts 58. Of course only a connection 55 and a connection 57 are visible in Fig. 2. 502 098? From the above description it appears that each column conductors can be connected to each line conductor by suitable activation of a selected drive element. Thus connecting for example, if the lower right drive member 24 is activated race, so that it is deflected downwards, its relay contacts 52, 58 column conductor C6 with row conductor R1. An input signal, '~ which is supplied to the column conductor C6, is thus transmitted on row leader R1 or vice versa. It is clear that one multiple drive elements can be activated to carry an input * signal, ~ which is applied to a row or column conductor, out on a selected number of column or row leaders. Due the serpentine device of the line guides there are no intersections, why advantageously the need to apply double-stretch conductor printing to avoid vikes.

The embodiment of the piezoelectric switching matrix the relay according to Figs. 3 and 4, with the reference numeral 62, differs from the embodiment 20 according to Figs. 1 and 2 fundamentally in the sense that the mobile contacts, carried by the drive elements 24 are not connected to column conductors through free-hanging conductors 60 as described joke above. Instead, carry each drive element, as best you can shown in Fig. 4, separate upper and lower movable con- beats in the form of short-circuit rails 50a resp. 52a, which are not electrically interconnected. Every upper short-circuit rail 50a is arranged to be able to come to contact with an associated pair of close to each other existing fixed contacts 56a and 56b, so that a circuit is closed in between. Similarly, each can lower short circuit rail 52a come into contact with associated pair of fixed contacts 58a and 58b, so that one circuit in between is completed. The pair of fixed contacts 56a, 56b are mounted on the lower surface 32 of the upper wall of the housing, while the pairs of fixed contacts 58a, 58b are mounted at the upper surface of the lower wall 34 of the housing. It then remains that connect the column guides to one of the selected pairs' fixed contact Qbz us and the line guides to the selected pair's other fixed contact providing a switching matrix relay. As will be appreciated the house walls 32 and 34 carry connections (not shown) similar to the connections 55, 57 (Fig. 2) for providing of electrical connection to the various fixed "\ contacts.

Fig. 3 shows with a dashed contour the comb-shaped, flat, undivided set 22 of eighteen drive elements 24, suitable for a 6 x 6 switching matrix. The one in Fig. 3 showed the arrangement of row and column conductors, which can be printed on the underside of the upper housing wall 32, including takes the six column leaders C1 to C6 but only three line conductors, for example R1, R3 and R5. The same leadership rank- mang is repeated on the outer or lower surface of the housing wall 34, except in the case of the designated line guides R2, R4 and R6 instead of the line conductors R1, R3 and R5. So- lunda is, for example, the line guide R1, which is printed on wall 32, routed for easy electrical connection with the fixed contact 56a, which is connected to (where the count again takes place from below) the first left drive element 24, the third, fifth, sixth and eighth the fixed contacts 56b of the left drive elements and that the fixed contact 56a of the ninth left drive element. So- lunda is the line conductor R2, which is printed on the housing wall 32 lower side, connected to the fixed connector 58a, which is connected to the first left drive element, the third, fifth, sixth and eighth left drive elements fixed contacts 58b and the ninth left drive element tets fixed contact 58a. The line conductors R3 and R5 at that one arrangement and the line guides R4 and R6 at it the second arrangement is conducted in a serpentine-like manner for connection to the various fixed contacts shown in Fig. 3 the rates without crossovers.

As stated above, the routing of the column conductors is C1-C6 the same for the arrangements, which are printed on the two 502 598 10 the walls, except that for the one on the wall 32 column conductors C1-C6 are connected to selected fixed contact pairs 56a, 56b, while the column conductors C1-C6 at the arrangement on the wall 34 are connected to selected fixed contact pairs 58a, 58b. Although not shown, it will be appreciated that the two arrangements the corresponding column leaders of the many are jointly connected outside the switching matrix 62.

As shown in Fig. 3, it is printed on the wall 32 arrangement column conductor C1 connected to the fixed ones contacts 56b, which are connected to the first left ones and the first right drive elements 24 and to the second the fixed contact 56a of the right drive element. Further is arrangement of the wall 34 column conductor C1 connected to the first left and first right drive elements fixed contacts 58b and to the second right drive element tets fixed contact 58a. Thus, for example, if the first right drive element is activated, so that deflected upwards, as shown in Fig. 4, its short-circuit rail 50a the associated fixed contacts 56a, 56b, so that the column conductor C1 is connected to the row conductor R3. If, on the other hand, the first right drive element bent downwards so that the associated contacts 58a, 58b via its short-circuit rail 52a, the column conductor C1 to conductor R4. In a similar way it is clearly, that the first left drive element can be bent upwards to connect the column conductor C1 to line conductor R1 or down to connect the column conductor C1 to row conductor R2. All the other matrix the switching points for the connection of each column conductor to each selected conductor or selected conductor can be easily followed in Fig. 3.

In the embodiments described so far, connect each piezoelectric relay a single column conductor with one single row leader. At most telecommunications applications, such as telephony, must both sides of esuz 098 11 one circuit is switched simultaneously. To this end, switching The embodiment of the matrix embodiment 64 of FIGS variant of the embodiment according to Figs. 3 and 4 and built to connect each column leader pair of a- and ring conductors. Thus, switching the matrix 64 as shown in FIG. S a comb-shaped, planar set 22 of piezoelectric drive elements 24, shown with dotted contour and mounted on it in Fig. 2 As shown in Fig. 6, a pair of upper, electrically insulated short circuit rails 66a and 66b and a pair of lower, electrically insulated short circuit rails 68a and 68b mounted at each drive element free end. A pair of closely spaced fixed con- bars 70a and 70b are mounted at the interior of the housing wall 32. surface opposite and with a gap to each upper short-circuit rail 66a, while a pair of adjacent fixed ones connectors 72a and 72b are similarly mounted standing and with gap to each short circuit rail 66b.

Fixed contact pairs 74a, 74b and 76a, 76b are mounted on the inner surface of the house wall 34 opposite and with gaps to each drive elements 24 short-circuit rails 68a resp. 68b. On due to this construction connects, when a drive- element is deflected upwards, its short-circuit rail 66a it the fixed contact pair 70a, 70b, and its short circuit rail 66b connects the fixed contact pair 72a, 72b. Equally connecting when a drive element is deflected downwards, its short-circuit rails 68a resp. 68b the fixed contact pairs 74a, 74b and 76a, 76b. As shown in Fig. 5 is the column conductor pairs connected to one fixed connector in each of the pairs, which are associated with selected drive elements, for example the fixed contacts 70a and 72a, while the row conductor pairs are connected to the other fixed con- the beats 70b and 72b of the two fixed contact pairs, which are connected to selected drive elements.

The row and column leader pair arrangement, shown in soz å9s 12 Fig. 5, is printed on the opposite surfaces of the housing wall 32 and comprises six pairs of conductor R1-T, R1-R to R6-T, R6-R in a 6 x 6 switching matrix, but only three columns conductor pairs, for example C1-T, C1-R, C3-T, C3-R and C5-T, C5-R. This leadership arrangement is duplicated on 34 opposing surfaces of the wall for the other three columns the conductor pairs C2-T, C2-R, C4-T, C4-R and C6-T, C6-R. For the description assumes that those in Fig. 5 with solid lines showed the conductor lines are printed on the the outer surface of the wall 32 (Fig. 6), while those with broken lines shown the conductor stretches are printed on this wall interior. The same Convention may be applied to the arrangement, which is printed on the opposite of the house wall 34 surfaces. Again, the conductor arrangement on each surface is performed on in such a way that crossings are avoided. For this purpose requires a large number of situations leading transitions from one wall surface to the opposite wall surface, which made by means of plated holes or bushings 78.

In some cases, these penetrations are carried out at the sites for fixed contacts by utilizing conductive pins 80 as shown in Fig. 6.

Referring to Fig. 5, one of the columns extends a-conductor C1-T on the inner surface of the wall 32 to the fixed one contact 72a, which is connected to the eighth left drive element 24, and to the eighth right drive element fixed contact 72a via the conductor route 81, which is printed on the inner surface of the wall 32 with transitions to the wall 32 upper surface via the bushings 78 for connection to the the second left and fifth left drive elements fixed con- bars 72a. These fixed contacts are jointly connected to the fixed cone of the second and fifth right drive elements beats 72a via pins 80 and conductor stretches 81.

The column's one ring conductor C1-R extends over the wall 32 inner surface to the second, fifth and eighth left the fixed contacts 70a of the drive elements and via conductor 81 to the second, fifth and eighth right-wing drivers gsoz us 13 the fixed contacts of the elements 70a. Of course, the column two a- and ring conductors C2-T, C2-R laid out on the house wall 34 opposite surfaces in an identical manner for feeding fixed contacts 74a and 76a of the same drive elements.

Still referring to Fig. 5, the row extends an a-conductor R1-T on the inner surface of the wall 32 to the ninth the fixed contacts 72a of the left and right drive elements 24 and via a pin 80 and a coupling 82a, which is pressed on the upper surface of the wall 32, to the eighth left drive the fixed contact of the element 72b. The column's a ring guide R1-R extends similarly to the interior of the wall 32. surface to the fixed contacts 70a and the ninth left and right-hand drive elements and via a pin 80 and override ling 82b, which is printed on the upper surface of the wall 32, to it eighth left drive element fixed contact 70b. It is again clear, that the line an a- and ring conductor R1-T and R1-R are laid out on the surfaces of the wall 34 for feeding the counter- corresponding fixed contacts 76a and 76b of the ninth left and right and eighth left drive elements.

From the above it appears, for example, that the eighth the upward deflection of the left drive element leads to its short-circuit rail 66a connects the bonded fixed contacts 70a, 70b, and that its short closure rail 66b connects the associated fasteners contacts 72a, 72b. As a result, the column is connected an a- and ring conductors C1-T and C1-R with the row an a- and ring conductor R1-T resp. R1-R. On the other hand, connects the downward deflection of the eighth left drive element the column's two a- and ring conductors C2-T, C2-R with the row an a- and ring conductor R1-T, R1-R. All the other matrix the switching points for connecting any column a and ring conductor pairs to each selected row a and ring conductor pairs can be easily traced in the diagram in Fig. 5. Man see that in each case a single drive element together connect a single column leader pair to a single one 502 os 14 row of leader pairs. The printed row and column conductor circuits arrangements are made at four easily accessible housing wall surfaces without any crossings on any wall surface required.

Fig. 7 shows a preferred design of the free end for the drive element 24, when the movable contacts have the shape of crossing rails. For the switching matrix 62 according to Figs. 3 and 4 piezoceramic single pole relay designs The free end of each drive element 24 is split by one base wears 140, so that a pair of relatively independent, flexible fingers 142a and 142b have been obtained. Conductive pads 144a are deposited on the surfaces of these fingers adjacent to their free ends and are jointly connected through in an integrated manner a conductor stretch 144b, which is passed around the slot 140 closed end. Contact buttons 146 are attached to or plated on the pads 144a, so that they make electrical contact with these. It can be seen that the surface electrode 42 terminates before the pads 144a and the connecting stretch 144b. As realized, this short circuit rail configuration is duplicated on the lower surface of the drive element 24, the two configurations the positions are arranged opposite and opposite each other.

Due to this construction, the fingers 142a and 142b are bent independently of each other to ensure good electrical contact with the opposing pair fixed contacts, for example 56a and 56b in Fig. 4, in spite of minor variations in the relative heights and / or in despite possible insignificant rotation of the drive element in associated with its deflection.

For the switching matrix 64 in Figs. 5 and 6 piezoelectric dual pole relay configurations are free of each drive element end provided with a centrally located, deep slot 148, so that a pair of relatively independently flexible switching poles 150a and 150b have been obtained. Each pole is split via slots 140 in the manner shown in Fig. 7 and described above. šoz oss 15 The formation of the pads 144a, the connecting stretch 144b and the contact buttons 146 are duplicated for each pole as shown. The benefits gained through this construction, has been touched upon above.

It is thus clear that the above purposes, including those set out in the foregoing effectively achieved, and because some changes can be made to the above-described the constructions within the scope of the invention, refers to everything what is contained in the above description or displayed in the accompanying drawings are interpreted as illustrative and non-limiting.

Claims (10)

soz åss lb PATENTKRAV A piezoelectric switching matrix, comprising a planar set (22) of piezoelectric relays, each comprising an elongate drive element (24) with opposite fixed and free ends, at least one on each drive element and adjacent to its free end or ends mounted movable contact (50, 52) and at least one fixed contact (56, 58), characterized in that the fixed contacts (56, 58) of the relays are supported by supports (32, 34) in line with their contacts (50, 52), that the fixed ends of the drive elements (24) of a holding element (28) are held in relation to the supports in such a way that all the drive elements of the relays are located in a common plane, and that a plurality of first conductors (R1- R6), which are arranged on the supports as printed circuit conductors, and a plurality of other conductors (C1-C6) are permanently connected to at least one of said contacts of at least two different of said relays, the number of other conductors, the distribution of their connections to the relay contacts and the number of relays are related in such a way that any of the first conductors can be connected to any of the second conductors by activating a drive element of a corresponding relay for bringing into contact with each other its movable and fixed contacts, wherein said corresponding relay is the relay whose closing connects said first conductor to said second conductor. Switching matrix according to Claim 1, characterized in that the drive elements (24) of the relay set (22) are shaped as a uniform construction of piezo-ceramic material. Switching matrix according to claim 2, characterized in that said uniform construction has a cam-like shape with a common backbone (26), from which the drive elements (24) extend parallel to each other and separated, and which is attached to the holding element (28). Switching matrix according to claim 3, characterized in that the drive elements (24) extend in mutually opposite directions from the opposite sides of the spine (26). Switching matrix according to Claim 3 or 4, characterized by integrated circuits (46) mounted on the spine (26) for activating a drive element (24) of a selected relay. A switching matrix according to any one of the preceding claims, characterized by a housing (30) enclosing the relay set (22), said support being constituted by housing walls (32, 34). Switching matrix according to one of the preceding claims, characterized in that each relay comprises fixed contacts (56, 58), which are mounted on opposite sides of each side by means of said opposing housing walls (32, 34). movable contact (50, 52), each relay drive element (24) being arranged to be selectively activated to bring its movable contact (50, 52) into contact with either of its associated fixed contacts. Switching matrix according to Claim 7, characterized in that the permanent connection of the first conductors (R1-R6) is made to the fixed contacts (56, 58) of selected relays, and that the permanent connection of the other conductors (C1-C6) is made to the movable contacts of selected relays (50, 52). Switching matrix according to Claim 8, characterized in that the first conductors (R1-R6) are laid out on the surfaces of the opposite housing walls (32, 34) in such a way that crossings are avoided. Switching matrix according to one of the preceding claims, characterized in that the supports (32, 34) keep pairs of the fixed contacts (56, 58) at a distance from each other and side by side and in line with the corresponding movable contacts (50, 52), and the other conductors (C1-C6) are also arranged on their supports as printed circuit lines.