EP0196622B1 - Rotary and slide potentiometer (tap changer switch) - Google Patents

Abstract

In a potentiometer selector switch, it is proposed to arrange on a circuit board, in indirect arrangement, longitudinal contacts consisting of wire bridges which are swept by the wiper of a regulating element forming the actuating element of the switch when the wiper is rotated or displaced. The wire bridges forming the longitudinal contacts are insulated from each other on one side of the circuit board and at least one end of each of the bridges passes through the board to the conductor side where it is connected electrically and fixed mechanically, preferably by dip soldering.

Description

State of the art

The invention is based on a rotary or slide potentiometer according to the preamble of claim 1.

In a known rotary or slide potentiometer (FR-A 2 246 035), a longitudinally displaceable sliding block is guided along grooves in a rectangular housing and contacts a single elongated wire contact with the aid of a wiper element mounted on it. For the longitudinal displacement of the block carrying the grinder of the variable longitudinal resistance thus formed, a rotary wheel is arranged on the outside of the housing, which passes through the block supporting the grinder with an axis and engages on both sides with teeth arranged on the axis in a longitudinal toothing on the housing.

In another known rotary switch (US-A 4 082 925), point contact connections are successively made between a plurality of individual contacts supported by a base part and one likewise by Base part worn collector or mating contact, wherein a grinder touches one of the point contacts and connects to the collector by an actuating element under the action of a cam structure following the respective rastered switching movements.

Another known push button switch (DE-B 1 144 808) comprises a cut-out insulating plate which stores a push button which can perform a defined back and forth movement due to a pawl / spring structure and which alternately has different contact springs attached to it Insulation plate touches attached contact strips. These contact strips are connected by their free ends bent through corresponding openings in the insulating plate to corresponding leads of the printed circuit. The contact strips are flat, metallic longitudinal elements of a non-spherical shape, on which the ends of the contact springs slide on the push button.

In this context, it is finally also known (FR-A 2 461 980) to design a manually operated pushbutton piano so that tabs of generally U-shaped wire piece shape are arranged parallel to one another on a carrier plate and, when a pushbutton is actuated, an elastic one Rider covering overall, electrically conductive film connects two of the riders with each other, resulting in electrical contact.

It is generally known to control or regulate the speed in electrical machines, the temperature in heaters, ironing devices and the like. in addition to the respective electronic or electrical circuit, the like a known leading edge control. can be to provide actuating means or actuating elements to be actuated by the respective user, which enable the setting of a specific speed or a predetermined temperature. These actuators are usually potentiometers, designed as rotary or slide potentiometers, although very often there are still some latching options that can also be felt when adjusting or rotating the actuating means, so that the setting is carried out in stages, which is not only for most applications sufficiently precise, but is also preferred because this gives the user a clearer statement about the respective operating state - for example, in the case of an iron, a first or lower temperature level for sensitive tissue, a medium temperature level and a full load level, for example. If the existing potentiometer is only used in stages in this way anyway, so with its transition ranges it is essentially superfluous, the use of such potentiometers still has the considerable disadvantage that these inaccuracies have up to ± 20%, so that under certain circumstances even must include an additional need for calibration.

It can also be problematic if one switches to switches for this purpose, which would be conceivable, in addition to the considerably larger switch requirement of a tap changer also the fact that when assigning to a printed circuit board, the conductor tracks must be refined at considerable cost, at least in the switch area, for example the copper layers must be silver-plated if you drive over them with a switch contact, and you still have the further disadvantage here Buy that you have to work on the circuit board side with circuit elements and can not attach all parts on the component side, which can lead to assembly and space problems. After all, one would only get to flat contact points when refining conductor tracks, while contacting surfaces that are as spherical as possible requires ideal contact pieces; The use of stamped parts in the switch assembly also requires the coating of these parts, which are usually made of copper, with carbon or gold or silver plating and their complicated assembly.

The invention is therefore based on the object of providing a rotary or slide potentiometer which can be used without any problems for the purposes described, as a step switch, which is produced using inexpensive means and is easy to assemble and use, and is considerably more accurate than non-calibrated potentiometers with mechanical detent for example.

Solution of the task

The invention solves this problem with the characterizing features of the independent claim and has the advantage of a particularly simple and inexpensive construction, with the simple and quick arrangement the counter contacts to the grinder are particularly cost-effective, together with simple assembly and excellent contact making, also on a long-term basis, whereby the set values to be reproduced can also be specified with basically any desired accuracy, by simply equipping them with resistors the corresponding, but then also narrow tolerances.

The invention is based on the knowledge that, when detached from the actual potentiometer principle, the tasks are separated while the adjusting movement for the desired speeds, temperatures and the like is still continuous. It is possible to achieve constant electrical setting values for specified areas that can be identified by mechanical locking or in any case marking, namely over a predetermined range of variation to the right and left for marking or screening, precisely because in this twisting or adjustment range only the predetermined electrical value is to be achieved and therefore only a certain desired manipulated variable needs to be controlled.

Therefore, in the present invention, if the potentiometer or switch is actuated in the usual manner of a rotary or sliding potentiometer with mechanical catches or position markings, the electrical effect is that of a tap changer, since contacts which are insulated from one another (in electrical understanding) are in contact with a counter contact We will be connected. The switching movement takes place however, overall grinding continuously, so that the invention can be referred to as a rotary or slide potentiometer.

A particular advantage in the manufacture of the potentiometer according to the invention is that the counter-contacts to the grinder, which it touches during its (continuous) passage, consist of wire bridges with which the circuit board on which the switch with its essential elements is mounted directly , is loaded. In detail, the contact assembly is done in such a way that, and this constitutes an essential inventive moment, the contacts are in the form of longitudinal contacts in wire form, for example made of electrolytic copper or some other common good contact material, the assembly taking place automatically; a well-known pick and place machine pulls out predetermined conductor track pieces from a wire winding and equips the printed circuit board with such a wire length in the same way as if it installs a resistor on the printed circuit board from the assembly side in predetermined receiving openings of the printed circuit board. In other words, the counter-contacts to the grinder of the rotary or slide potentiometer according to the invention are longitudinal contacts in the form of wires, the bent ends of which are automatically inserted and bent into two openings in the circuit board by the assembly machine, the fixing of these wire bridges on the conductor track side in the usual way This is done in the same way and at the same time as all other electrical connections to this circuit board, usually by dip soldering and the like. Like. The wire bridges are applied directly to the component side of the circuit board and fixed by soldering on the other side, so that the Printed circuit board carrier and bearing or housing for the longitudinal contacts, while the actuating element of the rotary or slide switch or rotary or slide potentiometer thus formed, which also carries the slider and the collector track, can be attached to the printed circuit board in any way, preferably by, as for example in the case of a rotary potentiometer, passing a central axis of the rotary actuating element, which the user engages, through an opening in the printed circuit board and, on the opposite side, being latched with noses or otherwise held in place by resiliently recessed locking pins.

Advantageous further developments and improvements of the invention are possible through the measures listed in the subclaims. The simultaneous formation of the rotary or slide potentiometer for effecting momentary circuits, that is to say for supplementary or sole further contact only by means of keying, that is to say briefly and only as long as the element is actuated, is particularly advantageous. For this purpose, the actuating element is made of, for example, telescopically sliding parts, and when depressed a nose arranged on the movable part places a contact element of the grinder on one of the longitudinal contact wire bridges.

drawing

Fig. 1

eine bevorzugte Ausführungsform der Erfindung als Drehpotentiometer mit zusätzlichem Tastschalter im Längsschnitt auf einer lediglich teilweise dargestellten Leiterplatte,

Fig. 2

die Ausführungsform der Fig. 1 in einer Draufsicht und

die Figuren 3a und 3b

in verkleinerter Darstellung einmal den Schleifer mit zusätzlichem einstückigen Kontakt zur Momentkontaktgabe sowie im Querschnitt eine mögliche Ausführungsform eines Drahtkontaktes in Form einer länglichen Drahtbrücke.

An embodiment of the invention is shown in the drawing and is described in the following description explained in more detail. Show it:

Fig. 1

1 shows a preferred embodiment of the invention as a rotary potentiometer with an additional push-button switch in longitudinal section on a circuit board which is only partially shown,

Fig. 2

the embodiment of FIG. 1 in a plan view and

Figures 3a and 3b

in a reduced view the grinder with an additional one-piece contact for momentary contact and in cross section a possible embodiment of a wire contact in the form of an elongated wire bridge.

Description of the embodiments

The basic idea is to provide, in the case of a circuit element electrically effecting a step-by-step contact, on the one hand a continuously operated grinder with an associated continuously contacted collector return line, and on the other hand to design the mating elements touched by the grinder as wire bridges directly populating the circuit board. One therefore immediately obtains a step-by-step setting, with no change in the electrical variables in a predetermined setting range around a desired value because the same wire bridge is always contacted, on the other hand there is an advantageous sweeping over of a plurality of switching stages, the grinder being designed in this way can either bridge two steps briefly in the transition, i.e. touch both wire bridges, or, if this is not desired for any reason (exceptionally), can also slide over an insulating piece, which could be, for example, an intermediate wire bridge without an electrical connection on the conductor track side.

In the illustration in FIG. 1, the printed circuit board or printed circuit board is designated by 1, its conductor track side by 2a and its component side by 2b. The exemplary embodiment of the invention shown in FIG. 1 is a rotary potentiometer with a pushbutton switch, it being understood that the invention is not limited to this, but can include any type of control potentiometer; Correspondingly required modifications based on the features according to the invention are possible for a person skilled in the art. The circuit board 1 is the carrier plate for any electronic parts, resistors, integrated circuit modules and the like, not shown in the drawing. Like. And it also serves, namely by the Cu conductor tracks arranged on the conductor track side to link these electronic parts and the switching stages implemented. In the following, the exemplary embodiment is described as a rotary potentiometer and is designated as such throughout, with the proviso that the contacts are made in stages.

The actuating element 20 for the rotary potentiometer 21, which the user can directly attack for adjustment is composed of two parts, a lower part 7 in the plane of the drawing with an axis of rotation 7a, which part is axially fixed but rotatable in an opening or opening in the printed circuit board 1, and an upper part Part 9, which in addition to the circuit board has an axial possibility of movement in that it can be pressed telescopically with the possibility of resetting by a bias spring 12 and the lower part 7 in itself in the direction of the circuit board. Both parts 7 and 9 are roughly pot-shaped; the lower part 7 of the actuating element 20 passes through the (one-piece) axis 7a through the bearing opening 22 of the bearing plate 1 and is locked on the opposite side, preferably with the interposition of a locking bush 17, the passage opening of which is engaged by resilient pins 19 each having a nose 19a , so that when the actuating part 20 is pressed onto the circuit board, when the axis 7a with its resilient pin 19 has also penetrated the locking bushing 17, the whole thing latches onto the circuit board; namely resilient, because the locking sleeve 17 has molded, protruding spring elements 18, which prevent axial play after locking and ensure a smooth, trouble-free rotary movement of the actuating element 20.

A collector ring 23 is arranged in the area of the passage opening 22 on the printed circuit board 1 separately from the actuating element 20 and the passage opening 22, preferably in a ring-shaped manner Slider track can be referred to and consists of electrically highly conductive material and has an extension 5b, which extends radially from the slip ring track, initially forms a protuberance 5a, which serves as a stop for the rotary movement of the actuating element 20 and then passes through the circuit board 1 Connection with a given conductor track.

The lower actuating part 7 presses the grinder 4 against the printed circuit board 1 with the shape shown in more detail in FIG. 3a. The grinder 4 is supported on the slip ring track 5 by two preferably integrally formed slide contact tongues that are prestressed downward in the plane of the drawing, that is to say on the slip ring track, whereby the electrical contact to the slip ring track is simultaneously established, and is locked on the lower actuating part 7 by two pins 6 that pass through the openings 4b of the grinder 4. The grinder 4 consists of a suitable resilient material with good electrical conductivity and has a first grinder finger 4c, with which, as will be explained further below, it causes the contact connections when the actuating element 20 is rotated here. Opposite the grinder finger 4c, but basically to be arranged anywhere, there is another contact tongue 8 which is integral with the grinder 4 and which, as will be explained below, serves to make momentary contact.

The lower actuating part 7 continues upward, as indicated at 7b, approximately in the shape of a sleeve and engages with this sleeve 7b in an annular recess 9a of the actuating upper part 9, with mutual locking lugs 13, 16, so that the parts 7, 8 can be pressed against each other against the pressure of the biasing spring 12, but can no longer be released after the initial locking. To effect rotational driving, ribs 14 can be provided on the lower part 7, in addition to other means, which engage in corresponding recesses 13 in the upper part 9 for driving the same. The bias spring 12 surrounds a central axis 9b of the upper part 9 and is supported on a lower shoulder on the lower part 7. The actuating element 20 can be actuated by the user directly or in that a further rotating piece engages in an upper central receiving slot 24.

It is an essential feature of the present invention to design the contacts touched by the grinder finger 4c when the actuating element is rotated, generally when the actuating element is displaced, as flat-lying wire pieces in the form of wire bridges arranged on the component side 2b of the printed circuit board 1 to which the grinder finger 4c, which can still have a lower spherical protuberance, rests resiliently for good contact and slides on rotation. These wire contacts 3 can be arranged around the angle of rotation range of the rotary potentiometer 21, either following a square shape, as shown in FIG. 2, or in any desired configuration; in other words, the counter contacts for the wiper finger 4c are successive longitudinal contacts, formed by free wire lengths, arranged as wire bridges made of a suitable, highly conductive material, preferably electrolytic copper, on the component side and so, as shown in Fig. 3b, with their ends through usual, wire ends of resistors, capacitors and other circuit elements receiving openings of the circuit board 1 down on the Are routed and bent there.

It is therefore also a preferred feature of the present invention to produce these wire contacts in the automatic assembly process, by processing the usually existing and known assembly machine instead of conventional resistor assembly or other element assembly from a supply roll, simply cutting pieces of wire, arranging them in the provided through openings of the circuit board 1 and the ends are bent so that the wire contacts are stuck so far, whereupon they are then soldered to the underside and immediately connected to the corresponding conductor tracks. Such an assembly method is particularly cost-effective and simple and is above all of particular advantage for the later use of the rotary potentiometer, because with the wire contacts 3 or the conductor tracks connected to them, resistors can then be problem-free, even with comparatively narrow tolerances, and preferably connect immediately with the same pick and place machine so that you can achieve very precise electrical settings.

According to a preferred embodiment of the present invention, the wiper finger 4c is designed so wide that it briefly detects two of the longitudinal contact wire bridges arranged on the component side with a predetermined distance 3a (see FIG. 2) in the transition between the individual switching stages, i.e. both during the rotary movement Longitudinal contact wire bridges bridged and connected to each other. This can be advantageous electrically; Of course, there is also the possibility to switch isolating here by letting the slider slide off one wire bridge before contacting the other, or by interposing wire bridges, for example of shorter construction, which are not connected.

Another advantageous exemplary embodiment of the present invention includes the momentary contact which is still possible at the same time as a result of such an embodiment of the actuating element, grinder and mating contacts. This purpose is served by the radially projecting contact tongue 8, which is connected in one piece to the grinder 4 and, in the normal case and without the two parts 7 and 9 being telescoped into one another, has a predetermined distance from a specific or any longitudinal contact wire bridges 3. If, in a certain switching position, for example also in the out position, for example when the wiper finger 4c strikes the bent projection 5a of the wiper ring track 5, a certain signal is desired, for example for the maximum speed or a certain temperature, then the upper part 9 is depressed with the result that one attached to the upper part 9, radially projecting and on the resilient Contact tongue 8 of the grinder 4 directed nose 10 depresses the contact tongue 8 for making contact at the respective opposite longitudinal contact. This pressing down is resilient and ensures good contact, because there is a certain overpressing of the contact tongue 8, that is, by a certain overstroke, when the parts 7 and 9 are telescoped up to an inner stop, with the required contact force on the assigned mating longitudinal contact. For this purpose, the nose 10 on the upper part 9 is preferably designed as a spring element which is molded onto the upper actuating part 9; the shape of the spring can best be seen in the illustration in FIG. 2; it is fastened to the upper part 9 via approximately diametrically opposite lugs 10a and continues on both sides in an annular manner via the segments 10b, which are free to the upper part 9, to the actuating lug 10, which is therefore also elastically flexible, the overstroke of the telescoped parts 7, 9 fields and provides the contact force for contacting.

It goes without saying that, as indicated at 3 'in FIG. 2, the elongated wire contacts can also be arranged in a linear extension and then contacted in succession by a sliding potentiometer or by a rectilinear grinder.

Claims (9)

1. A longitudinal potentiometer comprising a slider (4) which is moved in sliding fashion by an actuating element (20) which acts on the slider, wherein

   a) the actuating element (20) for the slider (4) is mounted on a circuit board (1),

   b) in executing its continuous adjusting movement the slider (4) consecutively contacts wire contacts (3, 3'), which are of circular cross-section, have the form of a plurality of linear wire bridges extending longitudinally in the direction of its adjusting movement and are electrically insulated from one another, with contact fingers (4c) in such manner that contacting at indexed intervals is established,

   c) a sliding surface (5) is disposed on the components side (2b) of the circuit board (1) which comprises the wire contacts (3, 3'), on which sliding surface (5) the slider (4) is supported with sliding contact tongues (4a) for the electrical contacting and

   d) both the wire contacts (3, 3') and the sliding surface (5) with projecting end zones is guided through the conductor path (1) and on the conductor path side (2a) is electrically connected to resistors and assigned conductor paths.
2. A rotary potentiometer comprising a slider (4) which is moved in sliding fashion by an actuating element (20) which acts on said slider (4), wherein

   a) the actuating element (20) for the slider (4) is mounted on a circuit board (1),

   b) in executing its continuous adjusting movement, the slider (4) consecutively contacts wire contacts (3, 3'), which are circular in cross-section and have the form of a plurality of longitudinal wire bridges electrically insulated from one another and arranged in a quadrilateral formation around the rotary angle zone, with contact fingers (4c) in such manner that contacting at indexed intervals is established,

   c) a sliding surface (5) is arranged on the components side (2b) of the circuit board (1) which comprises the wire contacts (3, 3'), on which sliding surface (5) the slider (4) is supported with sliding contact tongues (4a) for the electrical contacting and

   d) both the wire contacts (3, 3') and the sliding surface (5) with projecting end zones are guided through the conductor path (1) and on the conductor path side (2a) are electrically connected to resistors and to assigned conductor paths.
3. A rotary potentiometer as claimed in Claim 2, characterised in that the slider (4) is held against the actuating element (20) by moulded-on pins (6) which engage into recesses (4b) and is pressed resiliently against the wire contacts (3).
4. A longitudinal potentiometer as claimed in Claim 1, characterised in that for the longitudinal displaceability of the slider (4), the corresponding wire contacts (3') are mounted in a rectilinear sequence in a staggered double row on the circuit board (4).
5. A rotary potentiometer as claimed in Claim 2 or 3, characterised in that for the rotation of the actuating element (20), the actuating element (20) comprises, on a lower part (7), a central rotary or bearing shaft (7a) which, passing through a bearing opening (22) of the circuit board (1), is retained on the opposite side of the circuit board (conductor path side 2a) by the engagement of projecting locking pins (19).
6. A rotary potentiometer as claimed in Claim 5, characterised in that a central locking bushing (17) is provided behind which engages the shaft (7a) - provided with resilient locking pins - of the lower actuating means part (7), which locking bushing (17) prestresses the lower part (7a) with moulded-on springs (18) from the conductor side, prevents axial play and facilitates a tilt-free rotary movement.
7. A rotary potentiometer as claimed in Claim 5 or 6, characterised in that the slider (4) is of substantially ring-shaped, integral formation, with a projecting contact finger (4c) for contacting the wire contacts (3) and with a further, radially projecting, resilient contact tongue (8) which in the normal state is arranged at an interval from a wire contact (3).
8. A rotary potentiometer as claimed in Claim 7, characterised in that the actuating element (20) comprises an upper and a lower part (9, 7), which can be inserted telescopically into one another under the resetting action of a prestressing spring (12) and where an actuating nose (10) is arranged on the upper part (9), which latter is moveable axially relative to the circuit board (1) and serves as push button, and is directed towards the resilient contact tongue (8) of the slider (4) in such manner that when the upper part (9) is depressed instantaneous contacting occurs.
9. A rotary potentiometer as claimed in Claim 8, characterised in that the actuating nose (10) is resiliently arranged on the upper part (9) to facilitate an excess stroke, which makes available the necessary contacting force, in the telescopic portion of the upper and lower parts (9, 7).

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