FR2490868A1 - ROTARY SWITCH - Google Patents

Abstract

THE INVENTION RELATES TO A ROTARY SWITCH FOR A PRINTED CIRCUIT BOARD CAPABLE OF SWITCHING POWERS OF THE ORDER OF SEVERAL WATTS. THE CONNECTION PINS 4-4 ARE IN ONE OF THE BRUSHES 16-16 WHICH ARE SEPARATED FROM THE DISC 20 OF WHICH ONE SIDE INCLUDES A CONDUCTIVE CONFIGURATION 46 BY ANOTHER DISC 19 OF INSULATING MATERIAL INCLUDING OPENINGS 28 ARRANGED IN A CODED WAY TO CORRESPOND TO THE COMBINATIONS EACH ANGULAR POSITION OF THE SWITCH'S CONTROL AXIS 1. SO, FOR EACH OF THESE POSITIONS, EACH BRUSH 16-16 MAY HAVE ITS CONTACT END WITH REGARD TO THE NON-CONDUCTIVE MATERIAL OF THE DISC 19 OR, ON THE CONTRARY, WITH REGARD TO AN OPENING 28 OF THIS DISC. IN THIS LATEST EVENTUALITY, THE END OF THE BROOM PASSES THROUGH THE CORRESPONDING OPENING 28 AND COMES INTO CONTACT WITH THE CONDUCTIVE PART 46 OF THE DISC 20. THE INVENTION FINDS AN APPLICATION IN THE FIELD OF ELECTRONIC CIRCUITS.

Description

The present invention relates to a rotary switch and, more

  particularly, a rotary switch for a printed circuit board capable of cutting or establishing continuity between circuits traversed by electrical signals of a power of up to several watts. In low-current electrical applications, in the fields of electronics, for example, rotating switches are used to establish or cut the metallic continuity between their connecting pins according to the angular position given by an operator to a button. command. These switches are small in size, since they are generally mounted on printed circuit boards and, furthermore, they must make it possible to make electrical combinations between their connection pins.

  different to meet the various use cases.

  In some rotary switches of this type, the metallic continuity between the connection pins is established by means of brushes, integral with these pins, which rub on the conductive surfaces of a disk having a printed circuit. The possible electrical combinations with such a switch therefore result from a kind of coding corresponding to the combinations between the conductive and insulating surfaces of the printed circuit. In some other switch models, the metal printed circuit has been replaced by a conductive pattern obtained by screen printing.

  by means of an ink loaded with the appropriate metal particles.

  These rotary switches are suitable as long as their brushes establish or cut - as they rub on a conductive or insulating portion of the circuits carried by low power electrical signals, for example of the order of 100 mW and generally less than 1/2 W. On the other hand, when it comes to signals having a power of several watts - this is the case of signals of 100 mA current at a voltage of 60V such switches are no longer suitable. Indeed, among other drawbacks, an electric arc phenomenon occurs when a brush cuts an electrical signal of this power, while passing from an electrically

  conductive to a neighboring insulating surface; the result is a training

  progressive metal on this insulating surface which ends up being

  destroyed by breakdown of the insulation.

  The object of the invention is to overcome such drawbacks by

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  simple and economical means which make it possible to produce a small-size, ultra-thin rotary switch for printed circuits capable of switching signals of relatively high power. To this end, the invention proposes a rotary switch in which the brushes integral with the external connection pins of the switch are separated from a first disk, one side of which is wholly or partly electrically conductive by another disk of insulating material having openings. arranged in a coded manner to correspond to the appropriate combinations at each angular position of the switch. Thus, for each of these positions, each blade may have its contact end opposite the non-conductive material of the

  insulating disc or, conversely, facing an opening of this disc.

  In the latter event, the end of the blade passes through the corresponding opening and comes into contact with the conductive face

of the first disc.

  Furthermore, the position of the brushes and connection pins which they are secured, their respective spacing and their maintenance are determined by nipples which are integral with one of the two half-shafts forming the switch casing and which penetrate into corresponding openings from the other half-shell during

  the juxtaposition of these half-shells, when assembling the boot.

  The different objects and characteristics of the invention

  will now be detailed in the description which follows, made in

  As a non-limiting example, with reference to the appended figures which represent: - Figure 1, the perspective view of the rotary switch subject of the invention; - Figure 2, the exploded view, in perspective, of the constituent parts of the rotary switch of Figure 1; FIG. 3 is a perspective view of some parts of FIG. 2 but at an angle for illustrating invisible details in FIG. 2; FIG. 4 is a plan view, on a large scale, of the disk comprising the openings; for establishing the electrical coding combinations between the rotary switch brushes; FIG. 5, a sectional view, on a large scale, illustrating the chamfer profile of the extreme edges of the coding openings of the disk of FIG. 4; FIG. 6, a plan view, on a large scale, of the disk comprising an example of electrically conductive configurations,

associated with the disk of Figure 4.

  We will begin the description by referring first to

  Figure 1 which illustrates the rotary switch of the invention, ready to use. It appears to consist essentially of a control shaft 1, a casing formed of two half-shells 2 and 3 trapping the connecting pins 4 which are spaced apart from one another in a pitch allowing implantation on a printed circuit board . A set of connection pins, not visible in the figure but identical to the pins 4, is arranged so

  similar on the side of the switch.

  Although it is not shown in the figure - because not the object of the invention - the control shaft 1 can receive the usual operating buttons .. Similarly, the switch can be equipped with a threaded sleeve which then slides on the axis 1 and allows, in known manner, the fixing of the switch on a panel

  by means of a nut sandwiching the panel between

same and the switch.

  FIG. 2, which illustrates all the components constituting the switch and on which the elements of FIG. 1 are recognized, namely the control pin 1, the two half-shells 2 and 3, the pins of FIG. connection 4 and 4 '. Reference is also made to FIG. 3, which shows the parts of the axis 1 and

  of the half-shell 2 not visible in Figure 2.

  The half-shell 2 serves to accommodate the control pin 1 and the associated elements such as the spring 6 and the ball 7 and the cylindrical stop 8. The latter is forcibly mounted in one of the openings 9 which are regularly spaced around the orifice 10 of passage of the axis 1. Thus, according to the opening in which the stop 8 is located, allows a greater or lesser angular displacement of the control axis 1 since the lug 11 meets this stop after a circular movement more or less important. The ball 7 cooperates with the spring 6 to form a locking device so that the operator operating the control shaft 1 physically feels, by a hard point, the passage of an angular position of the switch to another, which also corresponds to the angular pitch of the openings 9. For this purpose, the spring 6 and the ball 7 are housed in the opening 12 (Figure 3); thus, when the axis 1 is in place in the half-shell 2, the spring 6 makes its

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  office and push the ball 7 against the semi-cylindrical beads 13 or in the hollows between them. The half-shell 2 also comprises four centering pins 14 which serve to assemble the casing and six pins 15-15 'intended for the establishment and maintenance of the connecting pins 4-4' which are, as it is see in Figure 2, each integral part of a single piece with one end is a connecting pin, the other end being in the form of a broom 16-16 '. Each spindle broom 16-4 or 1'-V4 'has two semi-circular cutouts 17-18 and 17'-18'

  for the passage of the nipples 15-15 'of the half-shell 2.

  The control axis 1 is associated with the two disks 19 and 20 so that its rotation simultaneously causes that of these two disks. For this purpose, the axis 1 ends, in the part which is normally inside the box, by a pivot 21 visible in Figure 3 and two flats of which only one referenced 22 is visible in this figure, the other flat being disposed symmetrically on the hidden portion. These flats 22 and the semicircular segments which join them are intended to penetrate forcibly into the corresponding openings 23 and 24 of the discs 19 and 20. The disc 19 comprises, around the opening 23, a flange 25 which confers on it a certain mechanical rigidity. When the disks 19 and 20 are in place on the control shaft 1, this flange 25 abuts against the face 26 (Figure 3). However, the thickness of the flange, the position of the face 26 relative to the face 27 (Figure 3) that the disc 19 rubs

  not against this face 27 but that there is between them a free space.

  It is in this available space, between the disc 19 and the face 27, that the brushes 16-16 'are housed. Their bending forces them to exert pressure against the surface of the disk 19 which is made of insulating material, for example teflon-loaded nylon. But the disk 19 is provided with windows 28 so that the brushes 16-16 'can be individually, either facing the insulating material of the disk or, conversely, facing a window 28, this situation depending on the position angle of the insulating disk 19 and the location of the windows

That he has.

  For ease of understanding, reference will be made to FIG. 4 which illustrates, on a large scale, a disc such as that referenced 19 in FIG. 1. The opening 23 and the flange 25 surrounding it are recognized; it should be noted in passing that the semicircular segments 29 and 30 are not identical: a polarization effect is thus obtained since, the male part of the axis I having a profile

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  similar, there is only one possible way to put the disk in place on the control shaft. The windows 28 are arranged in concentric circles 31 to 37, seven in number, that is to say in number equal to that of the brushes 16-16 '(Figure 2). It is obvious that the width of these windows is such that the brooms can enter there without difficulty. On examination of windows 28, we see that their length is variable, as well as their location on the insulating disc. In addition, considering the outer circle 37, the windows have the value of a quasi-semicircle so that only a sort of tooth 38-38 'of insulating material remains to separate them. Each disc therefore has a combined arrangement of the location and the length of the windows which is proper to it; it is therefore a particular code to

  each type of discs. That's why we call the -

  insulating disc 19 "coding disc". On the other hand, if one examines FIG. 5 which is a cross-sectional view of a window end - such as the end 39 of FIG. 4 - it can be seen that it has a chamfer 40 connected to the faces 41 and 42 by leaves 43 and 44. In this way, during the rotation of the coding disk, when the corresponding blade leaves the window, it passes from the approximate level of the bottom of the window 45 to the level of the face 42 by the transition ensured by the chamfer and the two connection holidays. The converse is just as true when the broom rubs on the face 42 and penetrates the window to the bottom 45. Obviously, the mechanical performance of the brushes is improved and, consequently, the quality of the contact between

  the brooms and the disc 20 (Figure 2).

  Indeed, it has been seen that the coding disk 19 was associated with the disk 20. Thus, when a blade passes through a window 28 (FIG. 2) of the coding disk, it rubs on the surface of the disk 20. Now, this disk is configuration carrier 46, of conductive material, printed on a suitable insulating substrate so that its conductive configurations provide the proper electrical connections between the brushes 16-16 'which have been allowed to reach it through the presence of windows 28 on the coding disc 19. Obviously, the configurations of the conduction disc 20 are variable; further, the configurations 46 illustrated in Figure 2, there is shown in Figure 6, on a large scale, another example of configurations forming conductive tracks roughly divided into two sectors; for another application, the disk 20 could even have a fully conductive face. Note that this disc 20 has an opening 47 identical to the opening 23 of the coding disc of the

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  Figure 4, that is to say, it has the same provisions of

  keying to facilitate its mounting on the control shaft 1.

  We will now return to FIG. 2 and refer more particularly to the half-shell 3. It comprises two imprints 48 and 49, one of the impression 48 for receiving and holding in place the pivot 21 (FIG. 1 control shaft, the other the impression 49 to allow a better seating of the disc 20 against the surfaces 50 and 51. Four blind holes 52 are provided to receive the centering pins 14 while the two sets of six blind holes 53 provide the housing of the nipples 15-15 '(Figure 3). Two of the flanks of the half-shell 3 comprise grooves 54 separated from each other by baffles 55. The grooves 54 receive the parts 56 of the connecting pins 4-4 ', the ribs 55 contributing to the maintenance and

  isolating said pins by inserting them between their parts 56.

  It will be noted that the centering studs 14 have a diameter slightly greater than that of the corresponding blind holes 52. This arrangement makes it possible to eliminate any additional part necessary for assembling the rotary switch. Indeed, when the disks 19 and are mounted on the control shaft 1, the latter having its pivot 21 in the recess 48 and its opposite end through -'ouverture 10 of the half-shell 2, when the brushes 16- 16 'are in place between the coding disc 19 and the face 27 (Figure 3), when the connecting pins 4-4' are arranged in their respective housing 54, it remains only to firmly secure the two half 2 and 3 shells. This is obtained by subjecting them to a sufficiently high pressure so that the centering pegs 14 penetrate forcibly into the blind holes 52 until the half-shells 2 and 3

be closely juxtaposed.

  It is obvious that the foregoing description has been

  given as a non-limitative example and that other variants

  can be envisaged without departing from the scope of the invention.

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