ARRANGEMENT FOR KEYBOARDS

Abstract: Arrangement for keyboards of the optoelectronic type which exhibit a surface area (1) in the form of a prism (16) divided up into fields (17). Each of the fiels is allocated an individual control function. They are intended to be contacted at the respective control function by a surface such as the surface of a finger tip. This causes a deflection of light, which is produced in the field, in relation to the luminous flux in the prism when there is no contact with the surface. The variation in luminous flux is supplied to a light-detecting sensor (19) by means of which an adequate command signal is generated. A control means (20) is so arranged as to produce a signal specific to each field (17) and capable of being selected from the signals from other fields. A single element or a small number of elements is/are provided as the sensor element (19). A signal processing means is also so arranged as to select the signal received from the sensor element in accordance with the specific signal characteristics for each of the fields, and as to transmit an adequate command signal for each field in accordance with said selection.

Description: Tit le: Arrangement for keyboards Technical Field: The present invention relates to an arrangement for keyboards which exhibit a surface area in the form of a prism divided up into control fields, each of which is allocated a control function and is intended to be contacted at the desired respective control func¬ tion by a surface such as the surface, of a finger tip, thereby causing a deflection of light, which is produced in the field, in relation to the luminous flux in the prism when there is no contact with the surface, said variation in the luminous flux being supplied to a light-detecting sensor by means of which an adequate command signal is produced. Description of the Prior Art: Keyboards containing a number of control functions are used for the control of different apparatuses and instruments. Examples of apparatuses with which such keyboards are used include program-controlled apparatuses such as washing machines and dishwashers in which by means of the keyboard an operating program is determined by selecting various components, machine tools in which various operating programs can be selected, and instruments for the production of a certain sequence, a sequence of characters- in typewriters and computers and a sequence of notes in musical instruments. It is assumed in this context that the keyboard arrangement is based on electrical functions. If a large number of control., functions is to be provided, then a keyboard of this kind will be of complex desigri comprising a lar e number of moving parts such as keys, electric switches and line branches. One possibility for simplification, at least in the mechanical sense, has however arisen in the form of so- caUed touch-sensitive keys, which do not have moving parts and which react to the contact of a finger upon a plate. The conductivity of the finger or its presence is utilized for this purpose as a conducting body in an oscillating circuit. Also disclosed in Swedish Patent No. 7613597-9 (publication No. 402 394) is the use of optical means in the aforementioned context. Said Patent Specification proposes the utilization for this purpose of the variation in the reflection within a prism, which can be produced if a body is pressed into full contact against any of the surfaces of the prism. By making use of this phenomenon it is possible, for • example by pressing the finger against the prism, to produce a variation which can be measured by a photo-sensitive element, in the light leaving the prism when the latter is exposed to a luminous flux. Technical Problem: The aforementioned and other principles for the formation of so-called touch-sensitive keys can be applied to the construction of a keyboard having a number of control functions, in the form of a single plate on which the various control functions are marked as areas to be touched with the finger tip. Notwithstanding the fact that a keyboard can be constructed in this way from a single plate, each control function still requires individual sensing organs which will react selectively to the control impulse supplied to the specific area associated with the sensing organ in question. Even if it has proved possible to eliminate mechanical elements such- as keys and electric switches, there remains thus a large number of elements and essentially equivalent to a multiple of the number of control functions. The wiring, too, is complicated and is essentially just as complicated as in the older, mechanical systems. The object of the present invention is to propose an arrange¬ ment for keyboards for a plurality of control functions, by means of .which the number of elements required can be reduced considerably. A particular concern of the invention in this respect is to achieve the aforementioned object by an arrangement which utilizes the said optoelectronic principle in order to provide the control function. A further object of the invention is t' permit the elimination of the influence from certain interference sources, such as periodic signals from the surroundings. The Solution: The object of the invention is achieved by means of an arrange¬ ment which is characterised in that a control arrangement is so arranged as to produce by means of transmitting elements a signal specific to each field and capable of being detected from the luminous flux signals from other fields, in that preferably a single element or a small number of elements fewer in " number than the number of fields is/are arranged as the sensor element, and in that a signal processing arrangement is also so arranged as to select the signal received from the sensor element in accordance with the specific signal characteristics of the transmitting elements and as to transmit an adequate control signal for each field in accordance with said selection, wherein the keyboard operates in a manner known in itself in accordance with the optoelectric principle. Description of the Drawings: Examples of the invention are described below in the form of six embodiments of the invention, together with certain variants. A reference is also made to appropriate, previously disclosed technology. In the interests of the clarity of the description, reference is made to a number of drawings, of which Fig. 1 shows by way of example the optoelectronic system referred to by way of introduction; Fig. 2 shows an external view of a keyboard in accordance with the first embodiment of the invention; Fig. 3 shows an internal view of the keyboard in accordance with Fig. 2, this view also providing a connection diagram at the same time; Fig. 4 shows a top view of the second embodiment; Fig. 5 shows a .top view of the third embodiment; Fig. 6 shows an external view of a part of a keyboard in accordance with the fourth embodiment; Fig. 7 shows a section along Line VIV-VII in Fig. 6; Fig. 8 shows a sectioned view of the fifth embodiment; Fig. 9 shows a' perspective view of the sixth embodiment; Figs. 10-12 show a front view of the same embodiment in three^'different types of application; and Figs. 13 and 14 show a. timing diagram for the operation of the arrangement in two different variants. Description of the Preferred Embodiments: As an example of the technology to which the invention is applied, an optoelectronic keyboard means of the previously mentioned kind is shown in Fig. 1. This is described in Swedish Patent Specification No. 7613597-9, to which US-PS 4 254 333 and GB Patent Specification No. 1 600 556 correspond. The basic arrange¬ ment can be used in a variety of ways to produce a keyboard. Its outside is formed by the outer surface 1 of a glass sheet 2 . The other surface 3 of the glass sheet is provided with a light-proof coating 4 with a number of windows beneath which are arranged glass prisms 5 in optical contact with the glass sheet. In Fig. 1 are shown three glass prisms 5 , each and every one of which is exposed to a beam of light 6 from a light-emitting ele¬ ment 7, such as a light-emitting diode, which receives power from a power supply arrangement 8. Adjacent to each prism ^ there is arranged a photo-sensitive element 9,such as a photo-diode,which is connected to a signal processing arrangement 10. For so long as the part of the glass surface 1 directly in front of each prism 5 is not touched, substantially total reflection will occur within the prism executed as a rectangular block with regard to its edges, and the photo-sensitive element 9 which is arranged at the edge will thus not be reached by the radiation from the light-emitting element 7 . If, on the other hand, contact is made with a surface, shown here as belonging to a finger tip 11 in complete contact With the surface 1 of the glass sheet 2 , the reflection will be interrupted at least partially and a certain quantity of light will leave the prism and will strike the photo-sensitive element 9 . The variation in the quantity of light striking the photo-sensitive element is used to generate a signal from the signal processing means 10 , which is used as a f j ntrol impulse for the control function allocated to the corresponding point of contact on the glass surface 1 . Reference is made to the aforementioned Patent Specifications, nowever, for a more detailed description of the principle in its various forms of application and of the equipment for the utilization of same. As will be appreciated from Fig. 1, the previously described arrangement requires for each control function a complete system consisting of a light-emitting element, a prism and a light-sensitive element. The power supply arrangement, on the other hand, can be common to all the light-emitting elements, as can the signal processing arrangement, in particular if modern semi-conductor technology is used and if a microprocessor, for example, is used for this purpose. The aforementioned situation, whereby certain vital elements must correspond in number to the number of control functions, whilst other elements can be shared, is also applicable essentially to keyboard arrangements in accordance with other physical principles which may be utilized in the present invention as described below. The following description of the application of the invention, which is made clear by Figs. 2-11 of the drawings, is associated with the optoelectronic principle described here. After the description which has been given of the optoelectronic arrangement, there now follows a description of the application of the invention to such an arrangewent. In this respect Fig. 2 shows a view of a keyboard 15 consisting of a glass plate 16 with a number of indicating areas 17 which bear designations 1.8 with the symbols A-J for the purpose of identifying certain control functions Also evident from Fig. is a light-sensitive element 19 , for example a photodiode, and a signal processing means, for example a microprocessor with an as¬ sociated power supply arrangement, for example a battery, which to¬ gether form a unit 20. Between the element 19 and the edge of the glass plate 16 there is present an air gap which .substantially eliminates the influence of light sources other than the elements 21. Becaus.. the light-sensitive element 19 is disposed to discriminate to a very nigh degree against light sources other than those which are to influence the element, such as the light-emitting element 21 , the level of interference is low. The signal level can also be ker.i low in this way, and no problems are encountered in distinguishing the deflection of. light which is utilized in accordance with the foregoing in the invention. In the event of extremely difficult external lighting conditions being encountered, additional discrimination can be achieved through a special signal processing technique, which is described later. Certain electrical circuits are also shown in the Figures. Beneath the glass plate 16 are further elements, and these are shown in Fig. 3. They consist of a number of light-emitting ele¬ ments 21, for example light-emitting diodes. They correspond in number to the number of fields 17 , and each is situated beneath its own field. Also shown in Fig. 3 are the light-sensitive element 19 , the electronic unit 20 , shown here in the form of a microprocessor 22 , and a power supply battery 23 . Since Fig. 3 also constitutes a wiring diagram, it is evident from this Figure that the light-emitting diodes 21 are separately connected to the microprocessor 22 and that the light-sensitive element 19 is also connected to same. Also shown are a number of circuits 24 intended for the transmission of signal impulses to those organs which are to be controlled from the keyboard. The keyboard can be installed in a washing machine, for example, in which case the various command fields represent different wash programmes. In a case such as this the signal circuits 24 are routed to the programmer of the machine for the purpose of causing it to execute the selected program. It is required of the various component parts of the arrangement that they shall be so executed as to permit the aforementioned optoelectronic function to be achieved. Thus, the light-emitting elements 21 shall be so arranged as to transmit their radiation into the glass plate 16 from its rear side, which is opposite the side on which the marking fields 17 are actuated by the pressure of a finger. The light-sensitive element 19 , on the other hand, is positioned at the edgt of the glass sheet with an air gap to accommodate the radiation which is reflected totally within the sheet upon the respective marking field 17 being touched. Although a single light-sensitive element is a preferred embod ment, it may be appropriate to provide a number of light-sensitive elements, especially in the case of large keyboards. In other words, the sheet does not contain individual prisms, but acts in its entirety as a single prism with a number of functions intended to produce total reflection within the glass sheet as soon as any of the marking fields 17 is touched. The glass sheet 2 is best provided with a non-translucent coating in those areas where^ t is wished to prevent secondary radiation into the sheet from external light sources. Fig. 2 shows how the fields 17 are clearly separated from each other and are arranged in rows; ten fields are shown here. This is suitable where the on/off position for a number of functions is to be selected. A different arrangement may be preferable for other control modes. Thus, Fig. 4 shows an arrangement intended to replace a so-called joy-stick. A joy-stick is generally used to select different degrees of two functions, for example elevation and lateral displacement, or speed and direction. In the arrangement shown in Fig. 4 a glass plate- 26 exhibits within a marked area 27 a very large number of contact fields arranged in horizontal and vertical rows, each of which has a corresponding light-emitting element 28 on the underside of the sheet. An arrow 29 is used to indicate that a movement in an upward sense will produce an increase in speed from zero, and an arrow 30 is used to indicate that sideways movements will produce changes in direction from straight ahead to left- and right-hand turns respectively. Depending on the position of the contact element, for example the finger tip, within the field 27 , a vehicle can thus be controlled with regard to its speed and direction of travel by moving the finger tip in different directions within the field. Fig. 5 shows an arrangement which is suitable for causing a change in direction. On a glass plate 31 is marked a circular, ring-shaped area 32 beneath which there are arranged in t .ε form of a ring a number of light-emitting elements 33 . An arrow 34 indicates that if a contact element, for example the finger tip, is moved in a clockwise sense within the circular, annular field 32, then a variation of a function will be achieved. The arrangement may be suitably applied to the adjustment of a means to different rotational positions. A typical application is in an antenna rotator. Although no radiation from the light-emitting sources is able, as a rule, to find its way out via the edges of the glass other than by the contact of a surface against the glass sheet, the light will still pass through the sheet to its external surface at those points where the contact fields are situated. In other- words, the .light-emitting elements are seen from the front side of the sheet. Accordingly they- can be used for marking the locations of the contact fields and alsu for indicating occupied control positions and waiting modes, etc. No mechanical elements in the form of keys have been present in the embodiments described up to this point. Thus commands are given simply by pressing an element, preferably the finger tip, against the corresponding area on the glass plate. Some other element may be used, if so desired, and this is necessary if it is to be possible to give commands with a gloved hand. The element in this case must provide total contact with the surface of the glass sheet, which can be achieved by the use of soft rubber, for example. There are also instances when the sense of the direct depression of some element, and not simpl contact, is required to be provided for physiological reasons. This is the case with calculators, for example, where it is extremely important to enter the correct number. There is accordingly a wish to overcome a certain amount of resistance to pressure, thereby preventing unintentional entries being made as a result of light contact on a surface. The same is substantially true of typewriters and keyboard instruments, and as a general rule those who are to use su'n instruments will have many years' experience of similar i istruments with keys which require to be depressed, etc. It may be desirable for this reason for the arrangement in accordance with the invention to be provided with keys. In spite of this the in¬ dention offers considerable scope for simple design in relation to previously disclosed keyboard arrangements. The opportunity is also provided for executing the arrangement as a totally sealed unit, since the glass sheet can be sealed into a case in such a way as to protect sensitive functions from external influences. A design which offers the aforementioned advantages is illustrated in Figs. 6 and 7. Fig. 6 shows part of a keyboard 36 which forms the keyboard of a typewriter. Shown in Fig. 6 are a number of keys 37 contained in openings 38 in a hard plate 39. As may be appre ¬ ciated from Fig. 7 the keys 37 form projections on a plate 40 made from an elastic material which is optically light-coloured under the radiation used. This plate is retained by the aforementioned plate 39 and by a subjacent plate 41 , which is also provided with openings 42 through which there extend projections 43 in an opposite direction to those of the keys 37 . Facing these projections is a glass sheet 44 with an upper surface 45 and a lower surface 46 . When the keys 37. are not actuated, the outer surface 47 of the projection 43 will exhibit a distance to the surface 45 of the glass sheet 44 . When a key is depressed, the surface 47 will be forced into contact with the surface 45 of the glass sheet thanks to the elasticity of the material in the plate 40 . This can be facilitated in the manner shown if the keys 37 and the projections 43 are connected to the rest of the plate by means of indentations. Since the material in the plate 40 with the projections 43 is in the form of an elastic material, the aforementioned ' total contact will be achieved with the surface 45 of the glass sheet 44 . The glass sheet 44 is in turn mounted in a housing 48 in which a number of light-emitting elements such as light-emitting diodes 49 are situated in positions opposite the projections 43.. A light-sensitive element 50 is arranged at the edge of the glass sheet. Means for a power supply and for signal processing are also provided in this design. Shown in Fig. 8 is a further simplified form of a keyboard comprising keys capable of being depressed. The keyboard means in accordance with Fig. 8 has as its casing a box 60 (shown only by its edge part) intended to enclose the electronic apparatus. A projecting edge 61 of the box 60 is enclosed by a cover 62 of elastic material, the main part 63 of which forms the front side of the means. The main part 63 is provided with raised parts 64 which form the 'keys'. With the help of the edge 65 of the cover 62 , which is attached to the box 60 , there is also attached a glass sheet 66 and a hard plate 67 containing holes 68 . The glass sheet 66 is included in the previously described manner in the optoelectronic means. The hard plate holds the cover 62 at a distance from the glass sheet. Its raised parts 64 can b:e forced down through the holes 68 , each of which is positioned directly in line with a raised part 64 . The raised parts will then reach the surface of- the glass sheet and will provide the specified function. It is stated in respect of the embodiments described here that the light produced at each control field is provided by jneans of a light source arranged at each field, preferably in the form of a light-emitting diode. It is possible as an alternative, however, to utilize a travelling light beam from one or more light sources. The light beam is in this case required to sweep over the prism so rapidly that the inertia of the eye will cause it to see the fields as if they were all lit simultaneously. Since the beam is present in each field for a specific part of the time of its sweeping cycle, the opportunity is provided for selecting those light signals which are obtained from the fields when they are touched for the purposes of giving commands. An embodiment based on this principle is illustrated in Fig. 9. Use is made in this case of a cathode ray tube 70 with an electron gun 71 . There is present opposite the electron gun a prism in the form of a glass sheet 72 . This glass sheet is so arranged as to be lit by the cathode ray tube,e'ther by constituting the image screen of the tube 70 or by the glass sheet being mounted in front of the image screen. At the edge of the glass sheet and separated from it hy a narrow air gap there is arranged a light detector 73 , as already described; see Fig. 2 and the associated descriptive text. The glass sheet 72 constitutes the control panel of the arrangement, and its control fields are formed by light fields 74 produced by electron beams. The means is connected to a control means which produces a sweeping movement for the electron beam, during which it is lit and extinguished in such a way that different images can be created. Such a means for the creation of images is, of course, already very familiar from oscilloscopes and television technology, and an ordinary video screen can be used. Also provided is a control means capable of detecting the field from which a signal received by the light detector 73 'originates. This possibility for the creation of light images on the glass sheet 72 is utilized in order to create the control fields 74 . The appropriate actuation of the control means enables various configurations to be constructed, in this way producing a variable control panel. The manner in which this can be used is shown in Figs. 1D-12. It is possible to imagine that one has a computer terminal via which tickets can be ordered. The terminal is equipped with a control panel of the kind described here. By indicating that one wishes to buy tickets, a control image in accordance with Fig. 10 can be produced on which various types of ticket are shown. It is assumed for this purpose that *T* indicates theatre tickets. By touching the field in question marked 'T', that is to say the field 75 in Fig. 10, the control means will be caused to be switched so that the electron beam instead constructs the configuration in accordance with Fig. 11. Following the indication that one wishes to buy theatre tickets, there will now appear a choice of indications for different theatres. Let us assume that one selects theatre *D' by touching the field 76 in Fig. 11; this will cause the image to change once more to provide a presentation of the seating plan for theatre *D', as shown in ig. 12. This indicates by the information transmitted to the- terminal what seats are already occupied. Each seat not identified in this way forms a light field which can be touched and in so doing produces a selectable signal via the light detector - 73 , which is then sent to the main computer so that the appropriate order details can be notified to the theatre in question. This is only one example of how a variable control panel can be used. This embodiment is described as incorporating a cathode ray tube, which is a commonly encountered means for the creation of light images. However, the idea of utilizing the optoelectronic phenomenon which is fundamental to the invention and the characteristic feature of the invention of detecting in this way individual signals deflected from one and the same prism can also be applied in conjunction with other means for the construction of images. It is thus conceivable to utilize it in conjunction with image screens which make use of LC technology, or with image screens which make use of a large number of light sources, such as the light board type. A simple projection means which moves a beam of light from one control field to another control field at a certain rate can also be utilized. Displays both in colour and black-and-white can also be used. In all the cases described the desired command function is achieved by detecting the position on the glass sheet of the contact element, that is to say the finger tip or the projection from the keyboard (Figs. 8-9). This is achieved by means of the light which is deflected on contact being made, so that the receiver, that is to say the light-sensitive element, is actuated. However, the receiver is unable to detect from which field the light was deflected to the receiver. The distance between each light field and the receiver cannot be used on its own to provide signals which can be distinguished with any degree of reliability. The substance of the invention is that the different light fields should be identified for the purpose of detecting which of them has been used, in the following manner. For this purpose the operation of the embodiments in accordance with Figs. 1-8 is described first: The aforementioned signal processing means, preferably in the fo'm of a microprocessor, is so arranged as to transmit an .ndividual activation signal to each and every one of the light-emitting elements. It is also evident from Fig. 3 how each and every one of these is connected via an individual circuit to the signal processing means 20 . The means is also so executed as to select the different signals arriving from the light-receiving element and which correspond to the signal transmitted by the light-emitting element in question when its light was deflected to the light-receiving element. It is possible to determine from this selection of the signals the Light-emitting element at which contact was established, and the signal processing means will transmit in " accordance with this the pre-determined, adequate command signal. Various methods can be used to create signals which are independent one from the other. Shown in Fig. 13 in the form of a diagram is a time displacement between the signals. Each and every one of the curves A-F indicates the signal processing for the different fields A-F , as shown in Fig. 2. The fields may be said to represent contact paths. Thus, in Fig. 13 the unbroken -lines indicate light signals from the light-emitting elements, and. the broken lines indicate periods during which individual contact paths are open for actuation from the light-receiving element. Thus, there is transmitted from the light-emitting element corresponding to the field A a flash of light at 52 , curve A in Fig. 13. For the duration of the flash 52 the signal processing means is receptive to the influence of a special contact path for a signal from the light-receiving element during a period 53 . Said contact path is so arranged that activation by means of a light pulse during the period 53 will produce a signal in the command circuit corresponding to the control function A . In the same way the light-emitting element at the contact field B will receive a light pulse during the period 54 , and within the same period or a slightly longer period, the corresponding contact path will be responsive to an impulse from the light-receiving element; see the period 55 . If, on the other hand, as shown in the curve C , the corresponding field were not to be covered, then no light pulse would be obtained during the ' period of• activation of the contact path corresponding to the field C , and no control signal would be transmitted. A new sequence, as shown on the right in Fig. 13, is begun once all the light-emitting elements have been passed. Fig. 13 accordingly illustrates most closely the case where all fields with the exception of field C are covered. The duration of the sequence must be sufficiently short for it to be shorter than the shortest contact period which may be required for command purposes. Fig. 14 shows how the light pulse can be divided up into a number of subsidiary pulses 56 , some ~ of .which are present within the activation area 57 for the contact path in question. The signal processing means is so arranged in this respect as to be activated only by a signal having a certain pre-determined frequency. Signals having a different frequency willl accordingly not produce a command signal, even if they occur during the respective receptive periods. By selecting a frequency outside the frequency of light in the surrounding area, it is possible to achieve a high degree of protection against incorrect commands occasioned by light arriving from outside. An arrangement in ac¬ cordance with the optoelectronic principle described here is in it¬ self relatively insensitive to light from the surroundings,although under certain specific circumstances the risk of interference with the operation of the arrangement may arise. However,the surround¬ ing light is usually either of a uniform nature, since daylight does not vary in accordance with any particular frequency, or, in the case of electric light, flashing in time with the mains frequency. By choosing a frequency at a certain distance from the mains frequency, it is possible to select from both daylight and -from electric light the light which is given off by the emitt¬ ing elements. . As an alternative to a time displacement of the light pulses, the" individual light-emitting elements can be caused to give off light at a frequency specific to each e-lement. The signal processing means shall be so equipped in this case as tr transmit the command signals in accordance with the frequency received, which also indicates that the corresponding field has been touched. Also included within the scope of the invention is the use of types of signal coding other than the use of di erent fre ¬ quencies.- The operation_o£ the arrangement, in accordance, with Figs 2 and 3 is accordingly that, in the event of one of the fields A-F being touched, . the light pulse from corresponding light-emitting elements will be transmitted onwards to the light-sensitive element. The signal processing means is sensitive* during the period for which the light pulse is transmitted/ to the influence of a specific 'gate', which is so arranged as to admit a command signal to that control organ which corresponds to the field in question when a light pulse is received by the light-sensitive element. If, on the other hand, the field is not actuated, then the light pulse will never reach the light-sensitive element, and no corresponding command signal will be allowed to pass. If, as has already been mentioned, the light-emitting elements are used to mark certain operations,for example the fact that a certain position has been occupied, then the light-emitting element in question can be allowed to remain lit fo.r longer periods between the identifying light pulses. If the sequence of signals is sufficiently rapid, this may be perceived by the eye as a continuous light capable of being seen from the front side of the keyboard. The possibility is also afforded of arranging separate light-emitting elements beneath the plate for the purpose of marking certain operations. If, in this case, these differ from a common code system, then they will have no effect on the command function. This will be the case, for example, if they emit a continuous light whilst the 'command transmitters' flash at a certain frequency; compare Fig. 13 and the associated description. The means in accordance with Figs. 6, 7 and 8 operates in a similar fashion, but with the difference that, instead of the light being controlled by the finger tip, control is effected by causing the projection 43 of the key plate 40 to move into contact with the glass sheet. A more complicated interpretation of the signals musX be applied in the case of the 'joy-stick' plate in accordance with Fig. 4. Thus, contact made with a certain vertical line "ill produce a certain degree of one function, for example the sp^ed of a vehicle, whereas the lateral positioning of the contact surface will influence the degree of another function, for example the amount of deflection of the steering wheels of a vehicle. In the embodiment in accordance with Fig. 5, the position of the field of contact is compared with the position of a component which is to be operated, for example ' the rotational position ofan antenna. Adjustment the -takes place until the latter po ¬ sition corresponds to the former. As has already been explained, use is made of one " transmitting element for each control function in the arrangement in accordance with the forms of the invention described here, where¬ as the entire arrangement makes use of only a single receiving ele¬ ment, or exceptionally, for example in the case of large keyboards,of a small number ofreceiving elements. The resulting simplification and thus the reduction in costs are considerable and increase in line with the increasing number of functions. In the optoelectronic system the reduction in the number of receiving elements, such as photo-transistors or similar, is of great significance, since the use of such elements as component parts involves higher costs than transmitting elements, that is to say light-emitting diodes. The reduction in the number of light- sensitive elements is achieved at the expense of having to use a more complicated signal processing unit. Nevertheless, the neces¬ sary functions can be achieved at a very low component price in the form of modern microprocessors. The cost does not increase in proportion to the number of functions, whereas the cost of light-sensitive elements increases in direct proportion to the number of elements. Where a large number of control functions is required, therefore, the increase in cost attributable to the need for more complicated signal processing will be negligible to all .intents and purposes, whilst the saving attributable to the reduc -d number of light-sensitive elements is of great sigrificance from the point of view of both cost and space. The invention permits the use of extremely complex control panels, including in consumer products where the cost is of great wμortance. Furthermore, the special advantages of the optoelectronic system, that is to say its reliable operation and its high degree of insensitivity to environmental influences, can be utilized even in complicated keyboards with a large number of control functions. So-called binary searching can be used in order further to increase the opportunities for separating a Large number of fields and in so doing shortening the search period. This involves searching over large fields, which are reduced after each search until the actual control field has been identified by a process of elimination. Searching of this kind reduces the search operations within the searching cycle and in this way ' shortens the search period. The more complicated signal processing which is required presents no difficulties if modern microprocessors are used. As an example of this type of searching, reference may be made to an arrangement in accordance with Fig. . search fields A-J are shown here. Searching can proceed in such a way that the first four fields are searched first as a single unit. If this reveals that none of the fields is being touched, then the next three fields are searched as a unit. If any of these fields is found to be being touched, then two of these fields must be searched as a unit. If either of these fields is found to be being touched, then a further search of one field will be required. If this field is found to be being touched, then the field which is being actuated will have been identified, and if it is found not to be being touched, then the other field of the two fields which have been searched will be the one which is being touched. If, however, during the search, any of the first four fields is found to have been touched, then two of these fields will be searched. If neither of these is found to have been touched, then one of the remaining fields will be searched, and the one of these two fields which has been touched will then be determined .in the manner indicated above. It is always possible in this way to ■ determine which of ten fields has been touched by the use of a search cycle which involves three searches, or four searches in unfavourable cases. A separate search of each field would, on the other h?nd, involve making ten searches. With reference to Figs. 13 and 14, the above functional description indicates how it is possible to select from the different fields by means of a time distribution of the illumination of each of the fields. A time distribution of this kind is already incorporated in a system with a scanning, image-constructing beam, as indicated in conjunction with Figs. 9-12. This existing effect can thus be applied to the detection of that field which is actuated by a command. By applying the scanning technique which is used to construct a television image, each Light field 74 (Fig.- 9) will be built up from a number of lines, each of which constitutes a portion of a line over the entire width of the image screen. This means that, in the case of each light field which is touched for a period having a duration extending over a number of complete compositions of the image (a complete image is usually produced in 1/25 - 1/3G of a second), a number of very short light pulses will be deflected towards the light detector 73 . Each and every one of these light pulses has its own specififc time interval within the entire scanning cycle. By the appropriate processing of the signals received from the light detector in accordance with the adequate time intervals which are obtained by controlling the scanning beam, it- is possible to detect every conceivable control field which is built up in the form of a light field. The binary searching method described above can also be applied to image screens by appropriate.programming of the process equipment. In the case of a cathode ray tube, however, the beam scans across the screen at very high speed, for which reason the use of binary searching appears not to be quite so convenient. As will have been appreciated from the above, the expression ' control field' is used to denote not only permanently marked, visible fields on the command .console, but also fields such as keys which are capable of mechanical operation, and also yields which consist only of illuminated parts of the surface of the control panel without having any permanent, material marking.

Claims: Patent Claims: 1. Arrangement for keyboards which exhibit a surface area (1) in the form of a prism (16) divided up into control fields (17), each of which is allocated a control function and is intended to be con- tacted at the desired control function by a surface such as the sur¬ face of a finger tip, thereby causing a deflection of light, which is produced in the field, in relation to the luminous flux in the prism when there is no contact with the surface, said variation in luminous flux being supplied to a light-detecting sensor (19) by O means of which an adequate command signal is produced, c h a r a c t e r i s e d in that a control arrangement (20) is so arranged as to produce a signal (21) specific to each field (17) and capable of being detected from the luminous flux signals from other fields, in that preferably a single element or a small number of ele- 5 ments fewer in number than the number of fields (17) is/are arranged as the sensor element (19) and in that a signal processing arrange¬ ment (20) is also so arranged as to select the signal received from the sensor element in accordance with the specific signal charac¬ teristics of the transmitting elements and as to transmit an adequate control signal for each field in accordance with said selection, wherein the keyboard operates in a manner known in itself in accord- ^ ance with the optoelectronic principle. 2. Arrangement as claimed in Claim 1, c h a r a c t e r i s e d in that the sensor element (19) is arranged at a certain distance from the prism (16), preferably in such a way that an air gap is formed between the surface of the prism and the sensor element, whereby light arriving from the surroundings can be distinguished from light from the transmitting elements. 3. Arrangement as claimed in Claim 1 or 2, c h a r a c - t e r i s e d in that the signals produced at each field are segre¬ gated by being transmitted in sequence, with each being allocated at least one specific time period (52, 54), and in that the signal pro¬ cessing means (20) is so arranged as to select the received signal by determining the time period or periods (53, 55) within whicft it was received and which correspond as a general rule to the one or more periods within which it was transmitted. 4. Arrangement as claimed in Claim 3, c h a r a c t e r i s e d in "3" that the control and signal processing means (20) are in the form of a processor so arranged as to activate in the aforementioned sequential manner the production of light at the fields (17), so that the signals are emitted for a period specific to each and every one of the fields, and as to hold open for the same period a signal path from the sensor (19) to a specific control line (24) which corresponds to the control function allocated to the field (17) in question, so that a signal supplied from the sensor during O the period of activation of each light production operation will produce a command signal in the corresponding command signal line. 5. Arrangement as claimed in any preceding Claim, c h a r a c t e r- i s e d in that the signal processing means (20) is so arranged as to conduct a binary scan of the fields (17) by controlling the 5 activation of the transmitter elements, so that several fields will be lit in a first operation and a smaller number in a se.cond operation until the signal processing unit -has identified the field being contacted either directly or by a process of elimination. Q 6. Arrangement as claimed in any preceding Claim, c h a r a c t e r¬ s e d in that the prism consists of a translucent sheet (16) on the one outer surface (1) of which the fields (17) are arranged, and on the other surface (3) of which, opposite to the afore¬ mentioned surface, light-emitting elements (21) are arranged in 5 conjunction with each and every one of the fields for the production of said light, and in that the light-detecting element (19) is arranged at the edge of the sheet connecting together both said surfaces. 7. Arrangement as claimed in Claim 6, c h a r a c t e i s e d in 0 that t e control and signal processing means (20) are so arranged as t produce in the light-emitting elements (21) a light signal flashing at a certain frequency, said frequency differing from the frequency of light in the surroundings, for example the mains fre q uency, and in that the control and signal processing means are 5 so arranged at the same time as to be activated only by signals received from the sensor element (19) having said frequency produced by the transmitter elements. 21 8. Arrangement as claimed in Claims 6 or 7, c h a r a c t e r i s e ^ d in that the light-emitting transmitter elements (21) a re so arranged as to be observable through the sheet (2) when in their light-emitting state and are so arranged as to be 5 controlled by the control and signal processing means (20) in such a way as to permit an instruction signal for the control of the . keyboard to be transmitted, for example a light signal indicating the temporarily assumed control position. 9. Arrangement as claimed in any of the preceding Claims 1, 2, 3, or 4, Tu c h a r a c t e i s e d in that the prism ( 72 ) is so arranged as to be lit by a luminous flux which, in a viewing screen arrangement, for example a cathode ray tube (70), is caused .to move over the surface of the prism so that light fields (74 ) are built up successively, said light fields forming said control 15 fields, and in that the selection of the light deflected from, each field takes place as detection by the signal processing means . ( 20) on the basis of the one or more periods during which the light field (74) in question was built up by movement of the beam. 10. Arrangement as claimed in any of the preceding Claim;. 6, 7, 8, or 9, 20. intended to perform the function of a so-called joy-stick, c h a r a c t e r i s e d in that the fields (27, 28) are arranged in a co-ordinate formation in a number of rows, thereby forming a surface area (27), and in that the signal processing means is so arranged, in accordance with the co-ordinates which 5 indicate the position of the transmitting element which is made to generate signals temporarily through contact against the surface of the sheet (26), as to transmit two command signals for two control functions, each of which " is allocated a particular co-ordinate within the surface area. 0 11. Arrangement as claimed in any of the preceding Claims 1, 6,7 or 9, c ha r a c t e r s e d in that for essentially each and every one of the fields on the surface (45) of the sheet (44 ) there is arranged a contact body (43) having a surface (47) by means of which said variation in the luminous flux is achieved through 5 '• contact with the surface of the plate, said bodies constituting parts of keys (37), so that a mechanical keyboard is formed by means of which said optoelectronic function can be performed -~ indirectly. 12. Arrangement as claimed in Claim 11, c h a r a c t e r i s e d in that the keyboard comprises at least one plate (40) of an elastic material having a number of keys ( 37 ) _each of which is connected to a contact body (43), said surfaces (47) of which, with the plate in the unactivated state, are situated .at a certain distance from the surface (45) of the sheet (44), said plate being made of a sufficiently elastic material to permit, through contact pressure tα applied to one of the keys (37), the surface (47) of its corresponding contact body (43) to be brought into contact with the surface of the sheet.

Inventors: BERGSTROEM ARNE, BERGSTROEM, ARNE
Applicants: NP NEW PROD NORDINVENT INVEST, N.P. NEW PRODUCTS NORDINVENT INVESTMENT AB
Application year: 1985
Main classification: H03K17
IPC codes: G06F3, H03K17