A TOUCH RESPONSIVE CONTROL PANEL

Abstract: Electrical control panels responsive to finger touch of marked areas on a front plate are used increasingly, such a touch establishing a coupling to electrode areas or other sensor means at the rear side of the plate. According to the invention the rear side of the front plate is used directly as a mounting base for the associated electronic components, whereby an integrated unit with a high operational safety is achievable.

Description: A touch responsive control panel. The present invention concerns a touch sensitive control panel of the kind comprising a front plate preferably in a dielectric material such as glass, and electrodes disposed on its reverse side together with with electronic circuits where the front plate carries markings that indicate touch areas, whereby a touch by a finger gives such an operative coupling to the respec- tive electrodes disposed on the reverse side that the panel unit may give off selective control signals by means of the electronic circuits. Such panel units or elements are increasingly used as control panels in various kinds of electrical and electronic equipment because they may advantageously replace panels with mounted mechanically acting switches or rotary or push¬ button activated elements in that a light touch upon a selected area may effect the desired function, such as a start or stop function or an ascending or descending control function without any use of mechanical action. Normally the units will function by capacitive coupling. In particular because this kind of control panel are known per se the general advantages of using them will not be discussed in detail here. It may be more relevant to note that the control panels according to the novel technology are predominantly manufactured in specialist establishments because it is no longer a simple mounting of ready-made special switches and controllers but the manufacture of a new type of product which comprises both the panel plate and at least the most necessary electronic circuitry. It has, however, been possible to prepare a kind of intermediate stage where the manufacture of the panel plate itself has been a specialist task whereas the electronic circuitry might be put on a conventional printed circuit board which could be prepared with suitable contact means for establishing contact with specific electrode areas on the reverse of the front plate. These defined areas are typically made as a coating of graphite powder which by a suitable technique has been fixed reliably to the reverse of the front plate so that the electrode areas thus created have a suitable extent with a well-defined position and are easily accessible for establishing contact with projec¬ ting contact elements on the printed circuit board disposed behind it, as these elements only need to abut the said coatings in a fairly uncritical fashion some¬ where on their extent. It has, however, been shown in practice that there may still be considerable contact problems because mechanical fitting of the relevant contact parts is relied upon. Possibly contaminating factors may make the establishment of an effective connection doubtful. According to the present invention the said prin¬ ted circuit board is dispensed with entirely in that one additionally places the relevant electronic components directly on the panel plate, to which they are fixed by e.g. cementing or to the electrode areas fixed thereon. The important thing is that by using the panel plate for carrying both the electrode areas and the requisite electronic components one may not only dis- pense with the circuit board but a totally integrated solution is obtained whereby the manufacturing facility may construct the units with high precision and thereby produce units with a very high degree of precision in an optimized manner and thereby produce units which dis- tinguish themselves by a high degree of functional reliability. The panel plate may in this connection have any size or shape, including an arched or vaulted shape and the unit may have a minimal thickness. The requisite components may be fastened by surface mounting (sol¬ dering) or cementing to the electrode areas or to other conductive layers on the panel plate or by cementing or casting in place of the housing of the components to the support. The panel plate may to a certain extent be used as > a printed circuit board, i.e. with fixed conductive f 5 strips between different terminal areas but the plate may also be used in such a way that it is supplied with a shielding coating around and between the operative electrode areas; thereby an EMC shielding of high quali¬ ty may be obtained, and the shielding coating may well 10 be used for fixing components which are not electrically connected to the shield. In connection with the integrated solution mentio¬ ned coatings on the panel plate are in focus, and it is a distinct possibility that the coating itself may be 15 differentiated to create different components such as resistors in a coating paste which has been laid out. The coating may play an active role also in connection with obtaining desired temperature compensation. It has been mentioned that the units in question 20 are normally working by means of capacitive touch coup¬ ling, but the invention is not limited to this, in that other coupling types may be used, e.g. based on induc¬ tive or optical sensing. An embodiment of the invention is shown in the 25 drawing, in which Fig. 1 is a perspective representation of a panel element according to the invention seen from the front, Fig. 2 is the same seen from the back, and Fig. 3 is a section through the same. 30 The element shown which is based on capacitive touch coupling has a glass plate 2 on the front of which are marked touch areas 4, while there may be window areas 6 in front of display units disposed behind the panel. 35 As shown in Fig. 2 such a window area 6 may be open toward the rear for showing a display which is independen of the plate while other window areas may be covered with display units 8 which e.g. by cementing may be fastened directly to the glass plate. Behind the areas 4 there are disposed conducting coating areas 10 on the reverse side which by means of suitable termination are connected to electronic compo¬ nents 12 which are fastened directly to the plate 2. Component leads or wires may be connected by soldering or cementing directly to the areas 10 or to conductor strips 14 which are connected thereto and the components may be mutually connected either by their own wires or by means of printed conductors. The connector for the whole element may be a multiple connector which is cemented thereto or even by wires leading therefrom. On the areas outside the areas 10 there may be a conductive shielding coating 16, see Figs. 2 and 3, onto which where there may fitted both components 12 and conductive strips 14. It is even possible to apply conductive coatings of a transparent type (ITO) , whereby also transparent plate sections 6 may be shielded or where transparent, active coating areas 10 may be estab¬ lished. In Fig. 3 it is shown that a so-called undercoat layer 18 may be applied directly to the glass plate. It may not only provide the base colour of the glass, but equally - as known from printed circuit technology - but also act as a suitable base for a subsequent printing of the conductive strings 14 and areas 10 which may consist of a silver compound applied by screen printing. On top of this there is applied an overcoat layer 20 which is generally covering, however not at the relevant sol¬ dering points. It is a possibility to print conductive strips on top of the layer 20 whereby a lower shielding layer 16 may extend unbroken across large parts of the whole unit. As mentioned the invention will not be limited to using a capacitive coupling mechanism for the touch coupling, because other useable principles are avai¬ lable, such as based on inductive or optical detection. The plate 2 will then have to be adapted accordingly, but it will still be the case that the active components and in any case immediately requisite components may be advantageously be mounted directly on the panel plate 2. Through the use of components directly mounted on the panel plate it will be particularly simple to make use of a an attachment which may deliver a discrete signal of acknowledgement of an operation performed on the panel, in that a hammer unit may act on the panel plate with an impulse for each push on the panel plate, which the user may perceive by the touching of the panel by the finger or by a corresponding emission of a sound.

Claims: P A T E N T C L A I M S 1. A touch sensitive control panel of the kind comprising a front plate preferably in a dielectric material such as glass, with markings indicating opera¬ tive touch areas and with electrodes or sensors with corresponding electronic circuitry disposed at the reverse side which by touching the plate with the finger and a thereby established operative coupling to a selec- ted electrode or sensor may give off a selective control signal, c h a r a c t e r i z e d i n the combi¬ nation of the electrodes or sensors being directly formed on or fixed to the reverse of the panel plate and that also relevant parts and components of the elec- tronic equipment is mechanically fastened to the same reverse side without use of a separate carrier plate. 2. A touch sensitive input panel according to claim 1, c h a r a c t e r i z e d i n that the components are fastened by Surface Mounting, cementing or casting. 3. A touch sensitive input panel according to claim 1, c h a r a c t e r i z e d i n that the reverse side of the panel plate is further prepared with conductive field- or strip areas for creating respetive shield or connection areas. 4. A touch sensitive input panel according to claim 1, c h a r a c t e r i z e d i n that one of the components directly fixed to the reverse side is a hammer device for delivery of mechanical acknowledgement impulses to the panel plate.

Inventors: NICOLAISEN MOGENS, NICOLAISEN, MOGENS
Applicants: NICOLAISEN MOGENS, NICOLAISEN, MOGENS
Application year: 1993
Main classification: H03K17
IPC codes: H01H13, H03K17, H05K1