GB2042820A - Connector assembly for a transducer - Google Patents

Abstract

A connector assembly (20) for electrically connecting a sound emitting transducer to a circuit board (22). The transducer is in the form of a thin disc (14) of conductive substrate with a piezoelectric element (12) mounted thereon and an electrically isolated central island being provided for a feedback circuit. The connector assembly generally includes a base member (28) which is clipped to the circuit board by spring fingers (32) and terminals (4, 48 and 50) soldered to the circuit board and having springy contacts to make the appropriate connections with a transducer clamped to the base member by a cover (56) removably secured to the base member. The transducer is clamped at a nodal radial between ring formations (36 and 64) of the base member and the cap. The connector assembly is easy to use and manufacture and provides selective removability of the transducer. An embodiment is described (Figs. 4 and 5) in which the transducer is held removably clamped to the base member and against the terminal contacts by formations of the base member. In another embodiment (Figs. 6 and 7) the base member is metal with depending terminals and an isolated central contact is provided. <IMAGE>

Description

SPECIFICATION Connector assembly for a transducer The present invention generally relates to acoustic wave devices such as transducers and more particularly to the electric connection of such transducers to other circuit members.

Transducers, which are well known in the art, are made of piezoelectric material. When the piezoelectric material is excited such as by an electrical signal, the transducer will vibrate and, in some applications, will produce a noise in response thereto.

In one kind of application, a transducer in the form of a thin piezoelectric element is mounted on a conductive substrate. By connecting an electrical signal to the element and the other to the conductive substrate, the transducer will be driven (or vibrated) at a given frequency.

In order to get a larger sound output from a transducer of this type, the piezoelectric element is divided into two electrically isolated portions. A feedback circuit is then connected to one of the piezoelectric portions. This type of assembly using three terminal connections, one to the conductive substrate and one each to the two portions of the piezoelectric element, will produce a much greater sound output than the conventional manner of attaching a terminal merely to the conductive substrate and one to the piezoelectric element. A representative type of circuit to produce the desired sound is disclosed in U.S. Patent No. 3,815,129, the contents of which are incorporated by reference herein.

In the past, the units which mount an electrically connected transducer of the type described, having a permanent, non-cyclable means of attaching or mounting the transducer to the unit, either by means of a solder connection or some sort of cement.

It is found to be desirable for both assembly and manufacturing purposes, to mount a transducer of the type described herein in a nonpermanent manner. This has been proposed to be done by means of an apparatus which includes a gasket and a housing wherein the gasket is made of resilient material having conducting regions.

The gasket is then laid upon a printed circuit board and the transducer is mounted thereover. A housing provides the necessary mechanical coupling for pressing the transducer against the gasket to electrically connect the transducer to the printed circuit board.

Although such an apparatus accomplishes its intended purposes, it is expensive in that is uses an elastomeric gasket and it does not lend itself to easy assembly in an ordinary manufacturing production process.

An object of the present invention is to provide a connector assembly for holding and electrically connecting a transducer having a piezoelectric element mounted on a conductive substrate to a circuit member, in a manner which is easy to use, manufacture and still provide selective removability.

The present invention accordingly provides a connector assembly for holding and electrically connecting a transducer having a piezoelectric element mounted on a conductive substrate, to a circuit member, comprising base means mountable on said circuit member, at least two resiliently formed metal terminals associated with said base means, one terminal having one end adapted to be electrically connected to said circuit member and the other end adapted to electrically contact said conductive substrate, the other terminal havng one end adapted to be electrically connected to said circuit member and the other end adapted to electrically contact said piezoelectric element, the ends of the terminals contacting said transducer being formed in a configuration to provide a normal spring action against the transducer for movement therewith, and transducer holding means associated with said base means for selectively securing said transducer in resilient contact with said terminals.

Specific embodiments of the present invention will now be described by way of example, and not by way of limitation, with reference to the accompanying drawings in which:~ Fig.- 1 is an exploded partially fragmented perspective view of one embodiment of connector assembly of the present invention; Fig. 2 is a plan view showing a transducer disc that may be used in association with the connector assembly of Fig. 1; Fig. 3 is a side sectional view of the connector assembly shown in Fig. 1 completely mounted on a circuit member; Fig. 4 is an exploded perspective view of a second embodiment of connector assembly of the present invention; Fig. 5 is a side view, partially in section, showing the connector assembly of Fig. 4; Fig. 6 is an exploded perspective view of a third embodiment of connector assembly of the present invention; and Fig. 7 is a side view, partially in section, of the connector assembly of Fig. 6.

With reference now to the accompanying drawings, the connector assemblies are intended to work best with a transducer of the type already described, i.e. one that is very thin in profile which lends itself to vibration upon electrical excitation.

One example of the type of transducer than can be used is shown in Fig. 2 in the form of a circular disc. It is understood, however, any generally thin shaped form could be used and still work in the present connector assemblies.

Turning to Fig. 2 in greater detail, the transducer, generally designated 10, is seen to include a piezoelectric element 12 which is mounted on a larger substrate 14 made out of conductive material such as brass. If a feedback circuit is desired, the piezoelectric element 12 will have an electrically isolated island 16. The electrical island 16 is then connected to the feedback circuit.

Turning now to Figs. 1 and 3 in greater detail, the connector assembly 20 is seen to be connectable to a printed circuit board 22. The printed circuit board has a plurality of mounting holes 24 and terminal holes 26.

The connector assembly 20 includes a base member, generally designated 28, including a housing portion 30 having depending mounting hooks 32 and snap protrusions 34 formed thereon. The mounting hooks are adapted to be snap fit into the mounting holes 24 formed in the printed circuit board 22. This mounting would be preliminary to any soldering operation as will be described in greater detail hereinafter.

The inside of the base member 28 has an upstanding nodal circular support 36 on which the transducer 10 is adapted to rest. It is to be noted that the support 36 has a knife-like edge to approximate a line contact only on the bottom of the transducer 10.

A plurality of vertical positioning ribs 38 are formed on the interior wall of the housing 30.

These ribs 38 will locate the transducer so that it will not touch the interior housing wall which might dampen any vibration which is produced by the transducer 10.

The interior of the base member housing 30 includes three terminal cavities 40, 42 and 44 which are adapted to mount three resilient terminals 46, 48 and 50, respectively therein.

Each terminal 46, 48 and 50 has a locking tang 52 formed thereon to abut against the shoulder 54 formed in the cavities 40, 42 and 44 to lock the terminals therein. It is to be noted that the terminals when initially mounted in the respective terminal cavities will extend above the height of the circular support 36 and will be resiliently pressed downwardly with the downward force provided on the transducer 10.

In order to provide the downward force and, therefore, the electrical connection with the terminals, a cover, generally designated 56, is provided. The cover 56 is in the form of an open ended cylindrical housing 58 having an opening 60 in its top and a plurality of snap latches 62 which are adapted to co-operate with the snap protrusions 34 formed on the base housing 30.

The inside of the cover housing 56 has a depending circular nodal ridge 64 which is in alignment with the circular support ridge 36 formed in the base member 28. The depending ridge 64 divides the cover housing 58 into a central resonating chamber 66 surrounded by an annular chamber 68.

It is important to note that the diameter of the circular support ridge 36 and the depending ridge 64 is designed to be substantially the same as the nodal diameter of the transducer 10. This nodal point or diameter is the place about which the transducer 10 would naturally vibrate. Therefore, if the transducer is held at this point, the least amount of dampening effect will result to produce the greatest amount of vibration and sound. In addition, for the purposes of preventing dampening, the terminals 46, 48 and 50 should be resilient so that a greater unimpeded vibration is generated. To amplify the sound, the resonating chamber 66 is provided while still remaining in contact with the transducer 10.However, even though all of these features would be necessary to produce the optimum amount of sound, it is not necessary to provide these features if an application of a lesser sound output is desired.

In use, the entire assembly 20 can be preassembled prior to any manufacturing operation.

First, the terminals 46, 48 and 50 are mounted in their respective terminal cavities 40. 42 and 44 respectively. Then, the transducer 10 is placed with the piezoelectric element 12 facing downward onto the resilient terminals 46, 48 and 50 and the circular support ridge 36. The cover 56 is then snap fitted onto the base member 28 so that the respective snap protrusions 34 cooperate with the respective snap latches 62.

When the assembly is completed, it is placed on the printed circuit board 22 initially so that the mounting hooks 32 are received in their respective holes 24. The printed circuit board 22 is then wave soldered to produce solder joints 70 to electrically connect circuitry (not shown) on the printed circuit board 22 with the transducer 10.

If, for any reason, it is desired to replace the transducer 10, the cover 56 is removed by unlatching the snap latches 62 from the snap protrusions 34. This operation can be performed many times.

Turning now to Figs. 4 and 5, a connector assembly 80 is shown mounted to a printed circuit board 82. The printed circuit board 82 has a plurality of mounting holes 84 and terminals holes 86 for purposes which will become more apparent hereinafter.

The connector assembly 80 is seen to generally include a base member 88 having two mounting hooks 90 which are adapted to be received through the mounting holes 84. Four upstanding support members 92 extend from the base member 88 which provide a platform for the transducer 10 when it is mounted on the base member 88. Two upstanding clamp members 94 are provided to clamp the transducer 10 in the base member 88. The combination of the four supports 92 and the two clamp members 94 comprises a holding means for the transducer 10.

The base member 88 has three terminal cavities 96, 98 and 100 which are adapted to receive three terminals 102, 104 and 106, respectively therein. Each of the terminals 102, 104 and 106 has a locking tang 108 which is adapted to engage a shoulder 110 formed in each of the cavities 96, 98 and 100. In this manner, each terminal 102, 104 and 106 is locked within its respective cavity.

It is to be noted that the terminals 102. 104 and 106 are resilient and, when they are in the base member 88, before the mounting of transducer 10, they extend to a height greater than the height of the four upstanding supports 92. When the transducer is held in the holding means, the terminals are resiliently pressed downwardly.

In order to facilitate insertion and removal of the transducer 10 a pair of cut outs 112 are provided on opposite sides of the transducer 10 which are alignable with each clamp member 94.

In use, the terminals 102, 104 and 106 are mounted in their respective terminal cavities 96, 98 and 100. The base member 88 is then mounted on the printed circuit board 82 by inserting the mounting hooks 90 into the respective mounting holes 84 in the printed circuit board. When this occurs, the bottom portion of the terminals 102, 104 and 106 extend below the surface of the printed circuit board 82.

The printed circuit board then can be wave soldered producing a permanent solder joint 114 with each of the terminals 102, 104 and 106. The transducer 10 is then mounted on the base member by aligning the cut outs 112 with the clamping members 94 and pressing downwardly.

It is understood that it is not necessary to have a three terminal feedback system. A noise can be produced by using the conventional two terminal system.

Turning now to Figs. 6 and 7, the connector assembly, generally designated 120, is shown in association with a printed circuit board, generally designated 1 22. The printed circuit board has three apertures 124. 126 and 128 formed therein for purposes which will become more apparent hereinafter.

The connector assembly 120 is seen to include an integrally formed unitary base member, generally designated 129, made of electrically conductive material. The base member 129 can be stamped and formed to the structure which is described in greater detail hereinafter.

The base member 129 has four upstanding support surfaces 130 and two end panels 131 formed therefrom. Each of the end panels 131 has a pair of top support tabs. The support surfaces 130 and the support tabs 132 comprise a holding means to hold the transducer 10 in the base member 129.

A pair of depending terminal tabs 134 and 136 are struck from the base member 129 and bent downwardly in an area below the end panels 131.

The terminal tabs 134 and 136 are each adapted to be received in the apertures 124 and 126 respectively. Each of the terminal tabs 134 and 136 have an outward bend 137 formed therein to provide a preliminary mounting means for the base member 129 in the printed circuit board 122 when received in the apertures 124 and 126.

Because the entire base member is unitary and made of conductive material, the terminal tabs 134 and 136 are electrically connected to the holding means which comprise the support surface 130 and the support tabs 132.

The base member 129 also has a frangible portion 138 formed therewith. The frangible portion has a depending tab 140 which is adapted to be received in the printed circuit board aperture 128. Formed on top of the frangible portion 138 is a resilient contact 142 which is adapted to contact the piezoelectric element 12.

For reasons which will become more apparent hereinafter, it is necessary that the frangible portion be electrically isolated from the remainder of the base member 129. To this end, there is provided a preformed break-away line 144 for breaking the frangible portion 138 from the base member 129.

In use, the base member 129 which is an integral unitary form is mounted on the printed circuit board 122 so that terminal tabs 134 and 136 are received through apertures 124 and 126 and depending tab 140 is received in aperture 128. The bends 137 in the terminal tabs 134 and 136 will prevent the base member 129 from dislodging from the printed circuit board 122. The printed circuit board 122 is then wave soldered resulting in three solder joints 146. The frangible portion 138 is then broken away at the break away line 144 from the remainder of the base member 129 to make it electrically isolated therefrom.

The conductive substrate 14 of the transducer 10 is mounted in the holding means between the respective support surfaces 130 and support tabs 132. In this configuration, the holding means contact the conductive substrate 14 of the transducer 10 which is electrically connected to the terminal tabs 134 and 136. The frangible portion 138 is in contact with the piezoelectric element 12. In this manner, an extremely low cost transducer connector assembly is provided.

Claims (14)

1. A connector assembly for holding and electrically connecting a transducer having a piezoelectric element mounted on a conductive substrate, to a circuit member, comprising base means mountable on said circuit member, at least two resiliently formed metal terminals associated with said base means, one terminal having one end adapted to be electrically connected to said circuit member and the other end adapted to electrically contact said conductive substrate, the other terminal having one end adapted to be electrically connected to said circuit member and the other end adapted to electrically contact said piezoelectric element, the ends of the terminals contacting said transducer being formed in a configuration to provide a normal spring action against the transducer for movement therewith, and transducer holding means associated with said base means for selectively securing said transducer in resilient contact with said terminals.

2. A connector assembly as claimed in claim 1 for a transducer in the form of a circular disc having an electrically isolated feedback island on its piezoelectric element; said connector assembly further including a third resilient terminal having one end adapted to be electrically connected to said circuit member and the other end adapted to electrically and resiliently contact said feedback island.

3. A connector assembly as claimed in claim 1 or 2 wherein said transducer holding means includes separate cover means removably mountable on said base means.

4. A connector assembly as claimed in claim 3 wherein said base means includes a generally cylindrical chamber having an interior annular nodal support ridge extending upwardly defining a circular line of support for a transducer when in contact with said terminals, said terminals being normally at a greater height than said support ridge, and wherein said cover means includes a generally cylindrical cover having an open end adapted to fit over the base means, said cover having an interior with a depending circular ridge in alignment with said support ridge and adapted to engage the top of a transducer to push it against said terminals.

5. A connector assembly as claimed in claim 4 wherein said depending ridge separates and defines a circular chamber surrounded by an annular chamber, said cover having an opening at the top thereof above such circular chamber to form a resonating chamber.

6. A connector assembly as claimed claim in claim 4 including interengaging lock means formed between said cover and said base means to selectively lock and remove the cover.

7. A connector assembly as claimed in claim 4 including a plurality of vertical positioning ribs formed on the interior of the base means providing points of contact against the periphery of a transducer to maintain it in a generally stable and concentric position.

8. A connector assembly as claimed in any preceding claim wherein the ends of the terminals adapted to be electrically connected to said circuit member are adapted to form a permanent electrical connection to said circuit member.

9. A connector assembly as claimed in claim 1 wherein said transducer holding means includes means integrally formed with said base means.

10. A connector assembly as claimed in claim 9 for a transducer in the form of a thin wafer and wherein said holding means includes bottom support means and top clamping means to stabilize and support such a transducer therebetween when mounted in the base means.

11. A connector assembly for holding and electrically connecting a transducer, having a piezoelectric element mounted on a conductive substrate, to a circuit member, comprising an integrally formed unitary base means made of electrically conductive material mountable on said circuit member, said base means including holding means adapted to contact the conductive substrate and for removably securing said transducer to said base means, and first terminal means adapted to be electrically connected to said circuit member, and second terminal means electrically isolated from said base means having one portion adapted to be electrically connected to said circuit member and another portion adapted to electrically and resiliently contact said piezoelectric element.

12. A connector assembly as claimed in claim 11 wherein the said first terminal means includes a tab portion depending from said base means.

13. A connector assembly as claimed in claim 12 wherein said first terminal means includes means to mechanically mount said base means on said circuit member.

14. A connector assembly as claimed in claim 11 for a transducer in the form of a thin wafer.

1 5. A connector assembly for holding and electrically connecting a transducer having a piezoelectric element mounted on a conductive substrate substantially as hereinbefore described with reference to, and as shown in, Figs. 1 to 3 or Figs. 4 and 5 or Figs. 6 and 7 of the accompanying drawings.