IL35075A

IL35075A - Monolithic keyboard and method for making same

Info

Publication number: IL35075A
Application number: IL35075A
Authority: IL
Original assignee: Sanders Associates Inc
Priority date: 1969-11-24
Filing date: 1970-08-07
Publication date: 1973-08-29
Also published as: US3627927A; FR2066529A5; SE362971B; IL35075A0; CH540530A; CA926453A; DE2041498A1; BE758202A; GB1272165A; NL7017168A

Description

Monolithic Keyboard and Method f or Making Same MONOLITHIC KEYBOARD AND METHOD FOR MAKING SAME Abstract of the Disclosure A monolithic keyboard constructed in layers with inexpensive materials and which has no conventional moving parts is disclosed. In one embodiment, the layers include a bottom or first layer of conductive materia a second layer of spongy material with holes cut therein, and a third layer of flexible printed circuit. This flexible printed circuit includes a sheet of insu lating material with conductive pads placed thereunder in registration with th holes in the spongy material. Key symbols are etched on or printed ever the conductive pads thereby indicating the placement of the keys. Depressing th key causes contact to be made between the respective pad and the first layer of conductive material. The spongy material gives the operator the "touch" of a standard typewriter keyboard. ces and r r.or ^.rr.cularly to keyboards employing a minimum of moving parts.

!. Description of the Prior Art In the prior art various keyboard arrangements have beer. -: ed for ent ring data into CRT displays, TV displays and the like. Various onsic tions in the design of these keyboards included reduction of complexity and cost while still retaining a high reliability. A further conside ration was that the keyboard have as nearly the same touch, as a standard typewriter keyboard.

U.S. Patent No. 3 ,382,338, (Arseneault) , describes a rigid conductor carrier and a flexible conductor carrier separated by an insulating layer which is stated to be of MHAR w&ich is neither spongy nor compressible. The Arseneault device achieves spring return action by means of two elastic layers. Accordingly, the Arseneault device does not employ the novel construction of Applicants' invention wherein an apertured spongy layer is placed between a rigid and flexible conductor carrier. In the device according to the present invention depressions of the flexible layer in registration with the apertures cause electrical contact between the conductors of the two carriers. The spongy layer provides a springlike return action* In U.S. Patent No. 3,308,253, (Ksakinowskl) , similarly shows a rigid conductor carrier and a flexible conductor carrier separated by an insulating layer which is neither spongy nor compressible. In fact, Krakimowski states that the insulating material is incompressible* Krakinowski apparently achieves springlike return action by means of an elastomeric layer which is adhered to the top side of the flexible conductor carrier. Accordingly, the Krakinowski device does not employ the novel construction of the present invention wherein an apertured spongy layer is placed between a rigid and a flexible conductor carrier so as to achieve springlike return ac ion.

Accordingly, it is an object* of this invention to provide an inexpensive and reliable keyboard* x JSS:jj Another object of the invention is to provide a keyboard which has no conventional moving parts.

Still another object of the invention is to provide a keyboard which is simple to manufacture and which has the "touch" of a standard typewriter keyboard.

Another object of the invention is to provide a keyboard which has tr. capability of shifting between upper and lower case symbols.

Yet another object of the invention is to provide an inexpensive key¬ board which is monolithic in structure and which is sealed against dirt and i! moisture. 1 i ' The invention accordingly comprises the features of construction, !i combination of elements and arrangement of parts which will be exemplifie ji ;! ji in the construction hereinafter set forth, and the scope of the invention will Ί I: be indicated in the c 'laims.

Briefly, the keyboard of the invention is monolithic in structure and jj has no conventional moving parts. The keyboard is constructed with a mini II ji mum of inexpensive materials arranged in layers over a base. The first j1 layer placed on the base is a shee.t of conductive material such as copper. li jj Over this conductive layer is placed a layer of spongy material with holes !i jj cut in it in registration with the arrangement of the keys. Over this layer i! !' of spongy material is placed a flexible sheet of insulating material. On the U underside of this flexible insulating material are conductive pads also in '•.I jj registration with the placement of the keys. Each of these conductive pads jj has a terminal attached thereto. The pads, terminals and flexible sheet of H insulating material are in combination a flexible printed circuit. Over the j; flexible sheet of insulating material is placed a rigid mask with suitably Brief Description of the Drawings The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of the preferred embodiment of the invention as illustrated in the accompanying drawings in which: FIG. 1 is a perspective view of the keyboard with the various layers shown cut-away.

FIG.2 is a cross section of the keyboard shown in FIG. 1 showing one such key depressed.

FIG.3 is a cross section of a second embodiment of the keyboard showing one key depressed and in addition showing an isolated key.

FIG. 4 is a schematic block diagram which might be used with the various embodiments of the keyboard of the invention.

Description of the Preferred Embodiments Now referring to FIG. 1 there is illustrated a perspective view of one embodiment of the invention. This view is shown in cut-away for ease of illustration. Mounted to a rigid base 24 are layers of inexpensive material which comprise the keyboard of the invention. Base 24 may be fabricated from any rigid insulating material such as phenolic. Placed over base 24 is a first layer of material or conductive sheet 20 which might be made of copper for example. Placed over conductive material 20 is a layer of spong material 18 with holes 22 cut therein. The holes 22 are cut so that they are registration with the placement of the keys on keyboard 10. Spongy materia 18 might be formed from foam rubber or any other compressible material. The thickness and density which contributes to the compression factor of the spongy material 18 are selected to give an operator the "touch"'' found on a flexible insulating material 14 as well as conductive pads 16 take the shape ihown. Pads 16 the re for e is in contact with sheet 20 at point 30 to cause a rcuit path. The operation of this circuit will be discussed hereinafter I Now referring to FIG. 3 there is shown a cross-sectional view o; another embodiment of tn e invention. A major difference between the key- i board 34 of FIG. 3 and th e keyboard 10 of FIG. 2 is that the sheet of conduc- I tive material is now flexi ble and adhered to the underside of flexible insulatin I I material 14 whereas the conductive pads and terminals connected thereto are now adhered to the base 24. Thus, in the keyboard of FIG. 3 the pads 42 as well as the terminals, not shown, are adhered to the base 24. These pads 42 I must be securely p>sitio: ed so that they will be in registration with the key I j positions. The spongy material 18 is placed over the base 24 and pads 42. i The holes 22 in the Ispongy material 18 are as before in registration with the pads 42. Over the jspongy material 18 is placed a flexible sheet of conductive material 40 which sheet 40 may be adhered to the underside of the flexible insulating material 14. The insulating material 14 in this case would only be used to prevent any possibility of electrical shock to the operator. symbol designators 28 and mask 12 would be shaped and placed in the same manner as previously di kcussed for keyboard of FIGS. 1 and 2. O: course, the symbol designators 28 may be etched into sheet 40 as mentioned in regar to FIG. 2. One of :he keys is shown in the depressed position so that the sheet 40 makes contact with a pad 42 at point or area 44.

Another embodiment of the invention is also shown in FIG. 3 wherein the sheet 40 is disc onnected at gap 39 and continues on as sheet 38. In this manner, key 36 is isolated from the remaining keys on keyboard 34. Tr ■8- contact between sheet 3 and pad 42 of key 36 would now be completely elec - trically isolated from the contacts of the other keys on keyboard 34. This configuration couldj be us ed in order that the keyboard have a shift capability, for example, i. e . , :apa|bility of selecting between uppe r and lower case symbols . Normally, when the operator is typing he will type the lower case symbols or, in the alternative, the keyboard may be set up s o that he is always typing the upper case symbols . If the operator depre s se s a key and simultaneously pres se s the shift key two independent electrical circuits will be made and will indicate to a decoding device that the symbol be recognized II as upper case or in the alternative , the lower case.- The operation of this circuit will be discussed hereinafter. Of course, it is understood that the jj shift capability shown in FIG. 3 for keyboard 34 may also be utilized with th keyboard 10 of FIG. 2. | It should be understood that this isolation of the shif key might not be required if the decoding device as sociated therewith is de signed accordingly. This will be discussed hereinafter.

It should be I further understood that the keyboard configuration as i! , :| de scribed in FIGS J I 1, 2 and 3 may be constructed in various ways . For example , the conductor pads of the se keyboards may be eliminated and replaced by conductive strips . For example, each strip might encompas s eight keys and in combination with this the conductive sheet might be broken ' i up into eight such j jsheets, each sheet also encompas sing eight particular key By placing the proper signals on the various c onductive strips a matrix arra '! will be formed, in this case for-,- 64 pos sible keys .

It should be furtjhe r understood that the keyboard of the invention ma jj have its keys placed thereon in any de sired arrangement. Also, if a conven i j tional keyboard design is required, the base holding the layer s of mate rial adapted to work with the ASCH code . If another code is de sired, then encod 48 would be de signed to convert the N inputs to that other code. The conduc tive sheet of keyboard 52 is connected to a voltage supply 46 so that whe a particular key is depressed, the voltage from supply 46 is coupled to a particular one of the N outputs of keyboard 52. The presence of this voltage is then encoded by encoder 48.

If the keyboard of the invention has associated therewith a matrix encoder in an array having N inputs and 7 output line s, then the addition of the shift key feature would not require complete electrical isolation of the shift key contacts . In this case the shift key output would be prewired to shift logic 50 whose function would be to invert particular bits in the encode 48 output when both the shift key 54 and another key were depres sed at substantially the same time.

If the keyboard of the invention has associated therewith a scanning keyboard encoder then the addition of the shift key feature might require complete isolation of the shift key circuit. Then the voltage supply 46 woul be connected to the conductive sheet for the shift key. The s canning input ' voltage s , not shown, would be connected in a scanning arrangement to the keyboard 52. Upon depre ssing the shift key 54, the voltage from supply 46 will be coupled to the input of shift logic 50 whose output is coupled to enc od 48. The function of shift logic 50 is to invert particular bits of*the seven bi ASCII output code so that the particular c ode will now be recognized as the same symbol but in the uppe r case or, in the alternative, lower case . If th shift key 54 is depre ssed without depres sing another key on keyboard 52 the the encode r 48 wojild be arranged so that the output from shift logic 50 woul i i not be accepted. If md ) re than one key on keyboard 52 were depre s sed at th s ame time , independent of the shift key feature , then the encode r 4≤ might e seen that objects set forth above, among those made receding de s cription are efficiently attained and certain de in the above constructions without departing from the on. It is intended that all matter contained in the above n in the accompanying drawings shall be interpreted as in a Limiting sense . ribed the invention, what is claimed as new and secured :

Claims

D- 2932 JSS:jj ■ ■ WHAT IS CLAIMED IS:

1. A keyboard, inc ding a plurality of keys, said keyboard, compi A . a sheet of c< .ductive material; B. a layer of spongy mate rial placed over said sheet, said spongy material having holes therein where said keys are located; and C. a flexible sheet of insulating material having conductive pads attached thereunder, said flexible sheet being placed over said spongy material and said pads being in registration with said holes; whereby a depre s sion of one of said keys cause s a respective pad to make contact with said sheet of conductive material.

2. A keyboard as d jsfined in Claim 1 , wherein said keys are designated by appropriate symbols appearing on the upper most side of said flexible ! j sheet over the respe ctive conductive pads .

3. A keyboard as defined in Claim 1 , further including a mask of material placed oyer said flexible sheet, said mask including holes in tration with said c nductive pads.

4. A keyboard as d efined in Claim 3 furthe r including a base to which t : ί bottom side of said she jet of conductive material is secured and to which the edge s of said mask are secured, whereby said keyboard is sealed from the ounding environment.