Abstract:
The invention relates to an electric switch, especially a piezo switch, with optical and/or mechanical feedback of the switching operation. The switch contains at least one switching element, especially beneath a cover panel, which can be activated by means of an activating element. This causes a switching signal to be generated and guided out via electrical contacts. The activating element itself is configured in the form of a passive luminous body consisting of an at least translucent material, which can be illuminated by active luminous means. The mechanical feedback of the switching operation can take place using a vibrator which is activated by the switching operation that has been initiated and conveys a vibrating motion to the luminous body.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to an electric switch, in particular a piezo switch, with optical and/or mechanical feedback of the switching operation. The invention is expressly, but not exclusively, related to piezo switches, but all functional principles of an electric switch are to be covered by the invention and consequently will be protected. In the following paragraphs, reference is only made to the preferred application of a piezo switch. 
   2. Description of the Prior Art 
   Such a piezo switch is disclosed for example in the subject matter of U.S. Pat. No. 4,430,595, in which in an approximately cubical housing a piezo element is disposed, which is actuated from above by an actuator, which with its actuation face extends through a cutout in a formed cover part. As the actuation face is provided a round, relatively flat face and the entire actuator is not illuminated. 
   DE 197 04 253 A1 disclosed an operating unit for motor vehicle components with a movable operating element, at whose front wall section an at least partially translucent symbol field is disposed, and a light guide element is disposed under the front wall section of the operating element which acts onto a switching member of the switch for the purpose of its actuation if the operating element is moved downwardly. The symbol field is directly illuminated by a light element via the light guide element, with the light element being disposed beneath the light guide element. The light guide element has an oblique surface for the incidence of light, which permits the off-center position of the light element due to the central position of the switch. 
   Of disadvantage herein is that for the actuation of the switch several different elements expensive of production and at least partially transparent (operating element with symbol field and light guide element with oblique surface) must be provided, which leads to increased material and assembly costs as well as also to a lower light yield through light absorption, in particular at the transitions of the different elements. An optical and/or mechanical feedback for the switching operation is not disclosed in DE 197 04 253 A1. 
   The invention is based on the task of developing further a switch, in particular a piezoelectric switch, of the above described type such that an optical and/or mechanical feedback of the switching operation takes place in an especially noticeable manner. 
   An essential characteristic of the invention is that the actuation element itself is developed as a passive luminous body of an at least translucent material, with the passive luminous body being illuminated via active illuminating means. 
   With the provided technical teaching the significant advantage is obtained that now the actuator of the in particular piezoelectric switch overall is formed as a luminous body, which is preferably comprised of a translucent synthetic material. 
   Such a synthetic material should thus be developed at least as a partially translucent material, but it can also be formed to be completely transparent. 
   This can involve here a single-layer or a multi-layer luminous body, such that with its back side illumination, the light overall is uniformly distributed in the luminous body developed as an actuator. 
   If the actuation surface (i.e. the face of the switch close to the user and to be pressed) is developed as a symbol field, the symbol body is especially intensely luminous. An especially impressive luminous phenomenon is obtained if the symbol body is three-dimensionally milled out of the front face of the luminous body, such that it is only necessary to press the symbol body in order to actuate the luminous body developed as an actuator, which, in turn, actuates the switching element in the switch. 
   This yields for the first time the advantage that no actuation housing for a luminous body is necessary, as is for example taught in DE 31 33 134 A1. 
   In it, the precondition is that in an approximately bulb-form opaque housing at the front side a translucent synthetic pane is inserted, which is back-illuminated by one or several LEDs. 
   This necessitates a structure requiring extensive space and yields an unimpressive illumination of the actuation face since the actuation face is relatively small. 
   SUMMARY OF THE INVENTION 
   This is the point at which the invention comes into play, which provides that overall the actuation body is developed as a luminous body, at whose front side the symbol body is preferable milled out as a threedimensional body. 
   This three dimensional development of the symbol body of the luminous body can be realized in two different embodiments. 
   First, in the first embodiment the opening in the cover plate, through which extends the luminous body, can be completely cut through such that the threedimensional symbol body, together with the remaining portions of the luminous body, extends fully all over through, for example, a cylindrical opening in the cover plate. 
   In this case the symbol body is illuminated as well as also its surrounding area in the luminous body itself. 
   In a different, second embodiment, it can be provided that only the symbol body extends through a correspondingly form-fittingly adapted opening in the cover plate and that the remaining portions of the luminous body are covered by the webs of the milling-out and opening in the cover plate are covered, such that in this case only the threedimensional symbol body itself projects through the openings in the cover plate and only the symbol body itself in this case also appears to be illuminated from the outside. 
   In the first case, thus overall the front facing of the luminous body with the symbol body formed thereon is illuminated while in the second case only the symbol body itself extends as an illuminated element through the corresponding openings in the cover plate and thus acts simultaneously as an actuation element. 
   This second embodiment is especially preferred within the scope of the present invention and herewith an impressively illuminated switch is obtained. 
   Since only the three dimensionally milled-out symbol body is visible from the front of the cover plate, this symbol body serves simultaneously as an actuation surface for the switch. This symbol body is illuminated according to the invention. This yields the advantage that, apart from the optically impressive appearance of the actuation surface, which is only characterized by the symbol body itself, simultaneously also locating by feeling the symbol body (without visual aid) is possible. 
   In the manner of a Braille symbol with a switch illuminated in such manner several illuminated Braille symbols can be accommodated, which thus are very well detectable by touch as actuating surface and are actuable through the corresponding push of a finger. 
   For the tactile feedback of the actuation of the luminous body different embodiments are available, which are all encompassed by the inventive concept of the present invention. These embodiments are each to enjoy protection by itself but also in combination with one another. 
   The first embodiment provides that the luminous body developed as an actuation element acts onto a catch spring and the catch spring, in turn, is seated on the piezo element such that, upon actuation of the symbol body, first the luminous body is moved by a switching path of, for example, 0.3 mm into the housing of the switch until the piezo element is actuated by the catch spring and outputs the corresponding signal. 
   A second embodiment of the invention provides that such a catch spring is omitted and that, instead, the actuation element (developed as a solid material luminous body) sits directly on the piezo sensor. In this case no tactile feedback of the switching operation to the user takes place since the luminous body needs only be moved by a switching path of for example 4 μm in order to generate a corresponding electric signal at the piezo sensor. 
   However, in all switch variants an optical feedback can take place, for example in such manner that the illumination onto the symbol body is changed for a different color or is switched on or off. 
   Important in all embodiments is thus the all-around illumination of the luminous body, which itself is developed as an actuation element. 
   For this purpose, on the backside of the luminous body—in the interior volume of the switch housing—several LEDs are disposed distributed on the circumference, and LEDs of a single color are preferably used which illuminate the backside of the luminous body fully. 
   Due to the illumination distribution in the luminous body, it is consequently illuminated uniformly over its entire volume and the luminance is transferred highly uniformly onto the symbol body disposed on the front side. 
   It is understood that it is also possible to provide differently colored LEDs in order to generate, for example, during one switching operation a green color of the luminous body as the illumination color and, when the switching operation is changed, to switch on the blue or green LEDs to allow the luminous body to light up in this case in said color. 
   In a third embodiment of the present invention a motor-driven feedback of the switching operation to the user is provided. 
   For this case it is provided that on the switch housing or in the switch housing a vibrator is disposed which, due to the initiated switching operation, is actuated and which outputs a vibrating movement onto the luminous body (and therewith to the actuator) such that the actuator mechanically vibrates when the switching operation is triggered. 
   For the development of this vibrator there are a number of feasibilities which are all encompassed by the invention. 
   A first embodiment provides that the vibrator is developed as a miniature motor, which drives a disk on which is disposed an eccentrically supported eccenter weight. 
   With the switching-on of this motor therewith the eccenter weight on the disk will generate a corresponding imbalance and this imbalance is transferred via the motor support and the motor mounting bracket of the motor on the housing of the switch onto the luminous body developed as an actuator. 
   It is understood that in a different embodiment the eccenter weight can be omitted and in this case the eccentrically supported disk itself forms the imbalance. 
   A different embodiment of the invention can provide that the vibrator is developed as a hammer break, i.e. in the manner of a bell, while alternately two different contacts are switched which also vibrate and also transfer this vibration movement to the luminous body. 
   An electromagnet or an ultrasound element can, of course, also be employed, which can output a corresponding vibration, also in the range of human perception. 
   A third embodiment can provide that the piezo sensor is also used as an active vibration element. In this case the piezo crystal is made to vibrate through a switched voltage applied from the outside, and these vibrations are directly transmitted to the luminous body since it is seated with a corresponding actuation extension directly, or via the spring washer indirectly, on the piezo crystal. 
   A second piezo element can equally well be employed, which is connected force-fittingly with the luminous body, which, only when the switching operation is switched on for a length of, for example 120 ms, exerts said vibration movement onto the luminous body. 
   It is understood that the feedback of the switching operation via said vibrators also functions independently of the previously cited illumination. 
   In other words, the protective scope of the present invention thus relates also to a switch with a non-illuminated luminous body, at whose housing a vibrator is disposed, which, during the triggering of the switching operation, exerts for a specific time of, for example, 120 ms, a tactile feedback in the form of a vibration onto the actuator. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following the invention will be explained in further detail in conjunction with several drawings which represent several embodiment feasibilities. Based on the drawing and its description, further characteristics and advantages of the invention are evident. 
     Therein depict: 
       FIG. 1  schematically an exploded view in section of a first embodiment of a piezo switch, 
       FIG. 1   a : schematically an exploded view in section of a further embodiment of a piezo switch without pressure piece of the actuation element, 
       FIG. 2  an enlarged representation of the piezo sensor according to  FIG. 1 , 
       FIG. 3  view onto the front side of the housing of the switch, 
       FIG. 4  view onto the front side of the symbol body penetrating the cut-through in the cover plate, 
       FIG. 5  view onto the circuit board with the LEDs according to  FIG. 1 , 
       FIG. 6  view onto the catch spring according to  FIG. 1 , 
       FIG. 7  embodiment according to  FIG. 1  in the assembled state with a minor modification in the region of the cover plate, 
       FIG. 8  view onto the front side of the embodiment according to  FIG. 7 , 
       FIG. 9  an embodiment modified relative to  FIG. 7  with a minor modification in the region of the cover plate and with the catch spring omitted, 
       FIG. 10  view onto the front side of the configuration according to  FIG. 9 , 
       FIG. 11  schematic section through a further embodiment, modified relative to  FIG. 7 , with a minor modification in the region of the cover plate and with mechanical feedback of the switching operation, 
       FIG. 12  view onto the front side of the embodiment according to  FIG. 11 , 
       FIG. 13  the switch according to  FIG. 11  with a different embodiment of the vibrator and the mounting bracket of the vibrator on the motor support, and 
       FIG. 14  the vibrator according to  FIG. 13  in side view. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The piezo switch according to the invention according to  FIG. 1  resides behind a cover plate  1 , which can be formed of any desired material, for example of wood, metal, glass or synthetic material. The cover plate  1  can be formed in any desired manner. 
   For the mechanical stabilization of the cover plate it can be backed with a support  2  which is comprised for example of a synthetic material. The support  2  can herein be adhered on the cover plate  1 . But it can also be connected with the cover plate  1  integrally with the material. 
   The support  2  can also be clamped mechanically on the cover plate  1 , with corresponding clamp brackets being available which are not further shown. 
   In the cover plate  1  a cutout  5  is disposed, with the cutout  5  being offset back from the fronting side front face  6  and forming a back-offset  7 . 
   On support  2  is fastened the housing  3  of a piezo switch and it is possible to employ any fastening means. The housing can herein be clamped, adhered, screwed or be connected in any manner fixedly or detachably to the support  2 . 
   The housing  3  is comprised essentially of a hollow cylinder, which has an inner cylindrical hollow volume  4 , comprising several steps. 
   In the proximity of the anterior front side an annular stop  8  is developed, which serves for the movement stop of the luminous body  9  developed as an actuation element. With respect to the embodiment example described here, but also with respect to all other embodiment examples, it will be noted in general in conjunction with  FIGS. 1 to 12  that the forming of the overall switch can be varied within a wide range. While the embodiment examples show that the elements of the switch (housing  3 , luminous body  9  and all other parts, such as, for example, the circuit boards  14  and  19 ) are developed as circular parts, however, the invention is not limited to this. The listed parts can also be formed in other cross-sectional forms such as, for example, elliptical, triangularly, hexagonally, octagonally, square and the like. 
   The representation of the listed parts as cylindrical parts, circular in cross section, is therefore to be only understood as an example. 
   It is important that the luminous body  9  is now developed as an actuation element, for example of a translucent synthetic material, and comprises a front symbol body  10 , which is formed threedimensionally. 
   The shaping takes place in such manner that only the symbol webs  40  defining the shaping of the symbol extend through the corresponding openings in the region of the cutout  5  of cover plate  1  and the remaining portions of the symbol body are covered by the webs  26  of the cover plate  1  disposed in the region of the cutout  5 . 
   This leads to an optical impression such that only the threedimensional symbol body  10  extends through the corresponding cutout  5 , such as is for example depicted in  FIGS. 4 and 8 . 
   Upon pressure onto this symbol body  10  the luminous body  9  is actuated in the direction of arrow  41 . 
   The symbol body  10  is preferably integrally with the material milled out of the material of the luminous body  9 . It is, of course, also possible to develop the symbol body  10  as a separate element from the luminous body  9  and to adhere, spray or fasten it in any other way on the remaining parts of the luminous body  9 . 
   The symbol body  10  is thus milled out in the axial direction with corresponding webs  40  down to the base of the annular shoulder  11 , with the annular shoulder  11  having an increased diameter and defining a circular cylindrical extension  12 . 
   This circular cylindrical extension  12  with the anterior annular shoulder  11  abuts on the annular stop  8  in housing  3 . 
   According to  FIG. 1  adjoining the extension  12  of enlarged diameter is a pressure piece  13  of decreased diameter, which extends through a corresponding cut-through  28  in circuit board  14  and is seated on an arched bottom  30  of a catch spring  17 , which, in turn, rests by means of extensions  29  developed at the cornered side on the peripheral margins of the piezo sensor  18 . 
   Consequently, if the symbol body  10  is actuated by a corresponding actuation force, it moves in the direction of arrow  41  in the direction toward the catch spring  17 , presses its arched bottom  30  through, such that with its arched bottom  30  it is in contact approximately in the center region on the piezo sensor  18  and switches it, which piezo sensor  18  will be described in further detail in  FIG. 2 . 
   According to  FIG. 2  on a support plate  19  a guide rubber  24  is disposed, which bears on its anterior side a piezo crystal  23 . 
   The entire configuration is covered by a pot-form synthetic cap  22 , which extends by means of pins  38  into associated cut-throughs of the support plate  19  and is anchored there. 
   Upon pressure of the catch spring  17  in the actuation direction  25  onto the synthetic cap  22 , consequently the piezo crystal  23  is compressed and outputs via the guide rubber  24  a corresponding piezo voltage onto the contact surfaces  42  disposed on the circuit board  19 . 
   On the circuit board  19 , additionally, associated evaluation circuits are disposed which amplify the piezo switching signal correspondingly and convert it into a corresponding evaluatable signal. This is conducted via the plug affixed on the circuit board  19  to the outside, which is comprised of the plug body  20  and the plug pins  21  attached thereon. 
   According to  FIG. 1  it is provided that on the circuit board  14  an illumination is disposed which, in the depicted embodiment example, is comprised of two diametrically opposing LEDs  15 , which are connected via a connection line  16  to the support plate  19 . 
   It is important that the LEDs  15  distribute their light in the direction of arrow  43  onto the entire back side of the luminous body  9 , such that the light acts onto the pressure piece  13  as well as also onto the annular extension  12 , such that the luminous body  9  overall is illuminated from the back over the entire surface and, in the sense of a light guide, conducts the light further highly uniformly distributed over the symbol body  10 . 
   In  FIG. 1   a  is schematically shown an exploded view in section of a further embodiment of a piezo switch, which, without finger-form pressure piece  13  of the luminous body  9 , operates as shown in  FIG. 1 . 
   The core of this embodiment according to  FIG. 1   a  is that the luminous body  9   a  is developed approximately roller-form and not disk-form with pin-form extension  13  as in the embodiment according to  FIG. 1 . Thus, in other words, according to the embodiment of the switch of  FIG. 1 , the finger-form pressure piece  13  of the luminous body  9  is now omitted and the new luminous body  9   a  itself actuates as a cylinder body (without interplacing such a pressure piece) via an actuation plate  47  the switching element  46  disposed beneath or behind, which switching element can be a piezo sensor. 
   The switching element  46  can be disposed directly on the circuit board  14 , which also supports the LEDs  15 , whereby considerable installation space in the depth dimension is saved. The switch according to  FIG. 1   a  thus requires a significantly smaller structural depth than the switch according to  FIG. 1 , which is especially of advantage when installing into instrument panels in the field of motor vehicles. 
   The emitted light of the LEDs  15  disposed horizontally with respect to the light guide element (upright LEDs or those of type  90 ) is subsequently also conducted essentially horizontally into the light guide element. With considerably lower structural height of the switch, hereby a very good light distribution in the light guide element is attained. In comparison to the embodiment according to  FIG. 1  and according to prior art, the LEDs  15  are thus disposed no longer beneath the luminous body. Due to the flat structure of the electric switching element, the light of the LEDs  15 , upright or developed as 90 types, is conducted horizontally laterally, into the luminous body, which leads to an ideal light distribution at simultaneously minimal structural height. 
   The structural parts provided in  FIG. 1 and 1   a  with identical reference symbols denote identical structural parts and will therefore not be described here. 
   In  FIGS. 3 to 6  the details of different parts are shown in view.  FIG. 3  shows the front view of housing  3 , and it is evident that on the housing additionally an axially extending groove  27  is worked in, such that the connection lines  16  can be carried axially along in the housing. 
     FIG. 4  shows that the symbol body  10  can be developed for example as an “@”. Thus this symbol body  10  is only visible from the front (from the viewing side of the cover plate  1 ) and lights up intensely. It is simultaneously the actuation element since only onto this symbol body the actuation force onto the luminous body  9  is conducted. 
   This yields a completely novel actuation and a completely novel appearance of such a switch since now through the pressure onto a specific symbol a switch is actuated, which previously was not known. 
   It is understood that the invention is not limited thereto. It can also be provided that the webs  26  in the region of the cutout  5  are omitted, such that the symbol body  10  with its symbol base in the region of the annular shoulder  11  is visible so that the projecting symbol lights up more strongly than the receding symbol base which sits approximately at the level of the annular shoulder  11 . 
   In a third embodiment it can be provided that the symbol body  10  is not milled out of the solid material of the luminous body  9  but rather that a symbol is adhered onto the front side of the luminous body and in this case only the environment of the symbols lights up. 
   However, the embodiment listed first is viewed as the preferred embodiment. Instead of adhering a flat symbol, it is also possible to adhere symbol bodies which are either also developed flat or as threedimensional bodies. Instead of adhering them, other connection mechanisms can also be chosen, such as for example spraying on and/or mechanical locking and the like. 
   Through the cut-through  28  depicted in  FIG. 5  in the circuit board  14  extends the pressure piece  13  of the luminous body  9  and subsequently rests on the catch spring  17 . 
     FIG. 6  shows this catch spring  17 , and it is evident that an approximately square metal platelet has corner-side oblique notching and consequently forms extensions with which the catch spring  17  in the margin regions of the synthetic cap  22  rests on it. 
   The catch spring  17  can be held in any desired manner in the interspace between the synthetic cap  22  and the circuit board  14 . 
     FIG. 7  shows the assembled state of the configuration according to  FIG. 1 , wherein it is only additionally shown that the back-offset  7  in the region of the cover plate  1  can be omitted, such that the symbol body  10  projects beyond the front face  6  of the cover plate  1 , while in  FIG. 1  it is flush with the front face  6  or recedes behind the front face  6 . The embodiment according to  FIG. 1  would yield a deeper formed encircling edge, as is shown in  FIG. 10 . 
   In  FIG. 8  this edge is omitted, since the  FIG. 8  is the front view of the representation according to  FIG. 7  and it can be seen that only the symbol body  10  extends out through corresponding openings in the cover plate and is hereby directly actuated. 
   However, the front edge of the symbol body  10  must always—even if only slightly—project beyond the front edge of the cutout  5  in order to ensure at all a—slight—actuation tolerance for the luminous body  9 . 
     FIGS. 9 and 10  show that the catch spring  17  can be omitted so that the pressure piece  13  rests directly on the piezo sensor  18 . 
   It is also shown that when applying an offset  7 , an encircling edge in the region of the cover plate  1  is formed in whose interior region now the three-dimensional symbol body  10  projects from corresponding openings of the cutout  5  and is intensely and noticeably illuminated. 
   The encompassing region of the wave-form symbol body  10   a  according to  FIG. 10  is not illuminated and is formed of the material of the cover plate such that only this wave-form symbol itself lights up noticeably and serves as an actuation element for the luminous body  9 . 
   In  FIGS. 11 and 12  as a further embodiment a piezo switch is depicted, which conveys a tactile feedback of the switching operation in the form of a vibration. 
   Here as a further embodiment example according to  FIG. 12  the symbol body  10   b  is developed as a musical note, which intensely illuminated projects from the cover plate  1  and serves directly as the actuation element. 
   It is evident that only a slight movement tolerance is required for the actuation of the luminous body  9 , since here also—as in the embodiment example according to FIGS.  9  and  10 —the catch spring  17  is omitted. 
   Important in this embodiment example is that the vibrator  31  in the depicted embodiment example is developed as a motor which drives a disk  32  about its rotational axis  33  in the direction of arrow  34 . 
   On the disk  32  is disposed an eccenter weight offset eccentrically with respect to the axis of rotation  33 . 
   When a switching operation is triggered, the motor is therewith switched on for example for a switching time of 120 ms, and the rotationally driven disk  32  with the eccenter weight  35  transfers an imbalance via the motor support  36  onto the pins  38  of the synthetic cap  22  of the piezo sensor  18  (see  FIG. 2 ), such that this vibration force is transferred in the direction of arrow  37  onto the synthetic cap which, in turn, vibrates and excites the pressure piece  13 , seated force-fittingly thereon, of the luminous body, which now moves in the direction of arrow  39 . 
   According to  FIG. 13  another embodiment of the vibrator  31  and of the mounting brackets of the vibrator  31  on the motor support  36  is shown, and here the connection to the pins  38  via a correspondingly formed band clamp fitting  44  is shown. In this band clamp fitting  44  the motor  45  is embedded via the motor support  36 , with the band clamp fitting  44  being stayed on the outer circumference of housing  3 . In contrast to  FIG. 11 , the disk  32  is not centrally supported and has no eccentric eccenter weight  35 , but rather the disk  32  itself is supported eccentrically on the rotational axis  33  and consequently forms an imbalance during rotation in the direction of arrow  34  or also in the opposite direction. 
   In  FIG. 14  an additional side view, rotated by 90 relative to  FIG. 13 , of the vibrator  31  with motor  45  is shown and the eccentric support of the eccenter weight  35  is here clearly visible. If the eccenter weight  35  is rotated about the rotational axis  33 , the eccentric vibrations are transferred in the directions of arrow  39  ( FIG. 13 ) onto the motor support  36 , and from there onto the band clamp fitting  44  and/or the pins  38  and from there onto the housing  3  and consequently onto the luminous body  9  or the symbol body  10 , where the user can pick up the vibrations tactilely with the fingers. 
   For the remainder the invention provides that the switch is at least partially hermetically encased in order to protect it against the effects of moisture. But in another formation it can also be developed in open structuring. 
   It is again repeated that the tactile feedback through the disposition of a vibrator  31  is to enjoy independent protection independently of whether or not the switch is illuminated.