FR2561016A1 - Seven-segment electromechanical indicator - Google Patents

Abstract

The indicator has an impact sensor (16) fixed to its casing for detecting when an armature (20) strikes a stop (25,26) limiting its movement. The sensor is a piezoelectric device. Several such indicators can be combined into a display. The indicator is tested by ascribing the output from the impact sensor to the activity of an electromagnet i.e. by detecting whether an armature has in fact moved as a result of an electrical excitation at an electromagnet.

Description

- 1 - Electromechanical display with magnetized movable paddles and method

  The present invention relates to electromechanical displays with

  magnetized movable pallets moved by inversion of the magnetic fields

  only remanent control electromagnets. Despite its better readability in a lit environment, this type of display is not or very little used as a digital account indicator for e-business transactions because we do not know how to control

  automatically their proper functioning.

  In the prior art, the automatic control of correct operation

  display is carried out by systematic character tests

  electrical characteristics of the display as shown, for example, by the French patent 1 2,258,480. This technique is suitable for electro-luminescent displays whose electrical characteristics depend on their display state. But it is not suitable for electromechanical displays with moving magnetic paddles because it does not allow

  to ensure the movements of the pallets.

  The object of the present invention is to provide an electro-mechanical display with magnetized moving paddles, the proper functioning of which is controllable.

  automatically so that it can be used as a digital indicator

  risk of account for commercial transactions.

  It relates to an electro-mechanical display with magnetized mobile pallets provided with a carcass having a cutout in which the pallets appear and supporting stops limiting the movement of the pallets and at least one shock detector fixed to the

  carcass detecting the impacts of the pallets on the stops.

  It also relates to an automatic control process of

  correct operation of the previous display consisting in controlling sue-

  ceasingly the movement of the pallets to be moved by reversing, one by one, the remanent fields of the eoneern4s control electromagnets and

  to ensure each time the uniqueness of the command by an electrical test

  stick at the terminals of the solenoid coils, and of the execution of the movement of the pallet solicited by a detection of

  its impact at the end of tilting on an earcasse stop.

  Other characteristics and advantages of the invention will emerge

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  of the description below given by way of example and given opposite the

  drawing in which: - Figure 1 is a perspective view of a display according to the invention, - Figure 2 is a schematic sectional view explaining the operation of the display shown in Figure 1 - and Figure 3 is an electrical diagram illustrating a mode of control of the display allowing automatic control of its correct operation. 1X The electro-mechanical affioheur represented in FIG. 1 is of the digital type with seven segments. It has a plastic carcass formed

  a base 10 covered with a cover 11. The base 10 carries electro-

  magnets 12 with residual magnetic field controlling the position of the segments

  ment. The cover 11 is fixed to the base 10 over the electro-ai-

  mants 12 thanks to balusters 13. On its upper face it has

  an eight-shaped cutout 14 in which appear or disappear

  feels segments 15 having the usual shape. A shock sensor

  piezoelectric 16 is glued by c8té on the cover 11.

  FIG. 2 details the mechanical arrangement of the pallets 20 carrying

  both the segments 15 of the display. Each pallet 20 is placed above a head 21 of a control electromagnet 12. It is formed by a bent arm 22 fixed by one end to the side of a segment 15 appearing or disappearing laterally in the cutout 14 and by the other end to an axis of rotation 23 placed inside the eapot 11 parallel to the longitudinal axis of the segment considered. Near its elbow, it carries a permanent magnet 24 placed opposite the head 21 of the electromagnet which controls it. Its travel is limited by two stops 25, 26 formed in the internal wall of the cover 11 on

  which is stuck on the piezoelectric shock sensor 16.

  It has been assumed in FIG. 2 that the magnets carried by the pallets 20 have their magnetic North face at the heads 21 of the

  control electromagnets 12 and there is shown, according to this convention-

  tion, a movable pallet in each of its two possible positions: to the left of the figure when its permanent magnet 24 is repelled by the remanent magnetic field of the control electromagnet 12 and that it

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  - 3 - shows its segment 15 in the cutout 14 of the cover 11 and to the right of the figure when its permanent magnet 24 is attracted to the field

  magnetic remanent of the control electromagnet 12 and that it esca-

  motes its segment under the side wall of the cutout 14 of the cover 11.

  The tilting of a pallet 20 from the retracted position to the non-retracted position or vice versa is obtained by reversing the remanent magnetic field of its control electromagnet 12 using a short-term current pulse applied in the meaning suitable for

  the excitation coil of the electromagnet. At the end of the down movement

  the pallet 20 strikes one or other of the stops 25, 26 and this

  impaet is detected by the piezoelectric shock sensor 16.

  FIG. 3 illustrates a mode of connection of the excitation coils of the pallet control electromagnets of a series of displays allowing multiplexed control and simultaneous implementation of

  good functional control tests.

  The excitation coils of the different electromagnets are placed

  created in bridge mutators allowing them to be applied in one direction or the other, for an instant, an excitation voltage + V

  creating a current pulse reversing the remanent magnetic field.

  Isolation diodes allow the switches to be shared

  ordered from the various mutators and thus reduce their number.

  The excitation coil S .. of an electromagnet controlling a pallet carrying the ime segment of the jme display is placed in the diagonal of a bridge, the other diagonal of which is connected to the terminals 0, + V d 'a source of excitation voltage. One of its ends is connected to point 30j of the bridge which is common to bridge mutators

  supplying the excitation coils S1j, S2j ... of the other electro-ai-

  control mants of the jth display. Its other end 31 is connected

  through diodes Dij, D'iJ at points

  bridge intermediaries 32i respectively 33i which are common to muta-

  bridge solvers supplying the Sil, Si2 ... excitation coils of the same i th segment of the other displays. The upper right branch of the bridge is constituted by a controlled switch A which connects point 30j of the bridge to terminal + V of the excitation voltage source and which is common

  to the bridge mutators of the excitation coils Sl, S2 ... of the jeme affi-

  choir. The lower right branch of the bridge is formed by an inter-

  controlled breaker B which connects point 30j of the bridge to terminal O of the excitation voltage source and which is common to bridge mutators

  excitation coils S1l, S2j ... of the jth display. The upper branch

  upper left of the bridge has a controlled switch Ci which connects point 32i of the bridge to terminal + V of the excitation voltage source and which is common to the bridge mutators of the excitation coils Sil, Si2 ... of the same th segment of the other displays. The lower left branch of the bridge comprises a controlled switch Fi which connects point 33i of the bridge to terminal O of the excitation voltage source and which is common to the bridge mutators of the excitation coils Si,

  S2 ... of the same ith segment of the other displays.

  The controlled switches A and B are in number equal to that of the displays and are used to select one of them in the multiplexed control while the controlled switches Ci and Fi are in number equal to that of the segments of a display and are used to select the segments. The switches A ,, Bj, Ci, Fi are blocked outside of a pallet tilting command. During such an order, a pair of them is A; Fi, or Bj Ci according to the desired direction of tilting, chosen for Aj Bj according to the display concerned and for Fi Ci according to the type of segment concerned, are rendered simultaneously passing the time to apply a short pulse of current to the excitation coil of the control solenoid

  considered palette and to invert its residual field.

  The display takes place in a sequential segment type, by

  segment type and, for a given segment type, display by

  choir. For example, by locating the seven segments of a display in the usual way with the letters a, b, c, d, e, f, g, we begin by updating the segments a by successively retracting the pallets of segment has displays to be changed, for example in the order of unit, ten, etc. and then on the successive display as required, segments a on the unit display then ten ... Then we continue

  by the segments b, c, d, e, f and g.

  For the tests of good functioning we proceed to verifications-

  systematic voltages at points 32i, 33i and 30j of the muta-

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  _5_ bridge solvers of the excitation coils which make it possible to ensure that a single coil is activated by law as well as by the detection of

  the impact attesting to the fact that only the pallet corresponding to the elect

  control magnet whose excitation coil is deactivated.

  For the rest, oh suppose that the retraction of a pallet is obtained

  by temporarily switching on a couple of switches

  from Bj Ciet the reverse operation by a transient conduction

  of a couple of Aj Fi controlled switches.

  During the zeroing and that is to say the successive retraction of the visible pallets of the displays to be modified, it is ensured

  activation of only one excitation coil at a time by a verification

  cation of the voltages at points 32i which must be zero with the exception of that of point 32 belonging to the bridge mutator of the activated coil, thereby indicating that the other display output coils

  to which the activated excitation coil belongs are not live

  and by checking the voltages at points 30j which must be equal to + V with the exception of that at point 30 belonging to the bridge mutator of the activated excitation coil, thereby indicating that the excitation coils of the displays other that the one to which the coil belongs

  are not energized.

  During the successive display according to the need following zeroing, we ensure the activation of a single coil of exeitation at a time by checking the voltages at points 30i which must be equal to + V with the exception of that of point 33 belonging to the bridge exciter of the activated excitation coil, thereby indicating that the others

  winding excitation coils to which the excitation coil belongs

  activated state are not energized and by checking the voltages at points 33i which must be zero with the exception of that of i point 30 belonging to the bridge amplifier of the activated loss coil indicating that the coils of excitation of displays other than that to which the activated exeitation coil belongs does

are not energized.

  The simultaneous adoption of an electrical test verifying that only one excitation coil has been activated at a time and of an impact detection test attesting to the fact that only the pallet is used ensures that

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  - 6- any time that the display works properly and makes it suitable for use as a digital account indicator for commercial transactions and, more generally, for any use or security

of the display is important.

  Without departing from the scope of the invention, it is possible to modify certain

  provisions or replace certain means by equivalent means.

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Claims (4)

  1 / Electromechanical display with movable magnetized pallets displaced by inversion of the remanent electromagnetic fields of control electromagnets (12) provided with a carcass (10, 11) having a cutout (14) in which the pallets (20 ) and supporting stops (25, 26) limiting the deflection of the pallets (20) characterized in that it further comprises, fixed to its carcass, a shock detector (16) making it possible to detect the impacts made by the pallets ( 20)   when they arrive at the end of movement on the stops (25, 26).   2 / Electromechanical display according to claim 1, characterized in   that the shock detector (16) is a piezoelectric shock detector   than. 3 / Method of automatic test of the correct functioning of displays according to   claim 1 consisting in operating them in a multi-   plexed by always activating only the single-coil excitation coil   three-magnet control both by checking and by character testing   electrical characteristics of the coil control circuit that there is   always only one coil energized at a time and by a detection test   tion of impact achieved by means of the shock detector that the movement of   the requested pallet has taken place.   4 / A method according to claim 3, characterized in that the electrical characteristics tests are tests for the presence of voltage across the excitation coils (Sij) of the control electromagnets (12).