CH646824A5 - PROXIMITY EFFECT TYPE SWITCHING PANEL. - Google Patents

Description

The present invention relates to a proximity effect type switching panel comprising a plurality of capacitors each comprising a control electrode and at least one servo electrode, arranged in capacitive relationship.

In one of its forms, a switch on a panel of the type concerned comprises a dielectric sheet carrying on one of its faces a control electrode and on its other face a servo electrode arranged in register with the control electrode and connected to a switching circuit. During use, the servo electrode is charged in such a way that when the control electrode is touched or approached, for example by a finger, the servo electrode emits a control signal to the switching. According to other provisions, such a switch is provided with two servo electrodes, one of which can be charged while the other is arranged to transmit a control signal to the switching circuit.

Control panels carrying such switches are used for an increasing number of applications. Examples include: keyboards for calculators, typewriters, telephones; domestic stoves, controls for television and sound reproduction apparatus, controls for reading display devices; elevator controls.

It will appear that these different control panels require different arrangements for locating the switch or switches that they comprise. It will also appear that, for mass production, it is desirable to standardize the type of control panel produced up to a limit compatible with customer requirements. This constitutes the main object of the present invention.

The present invention relates to a proximity effect type switching panel comprising a plurality of capacitors each comprising a control electrode and at least one relay electrode arranged in capacitive relationship, which is characterized in that said control and relay electrodes are light transmitting elements deposited on the opposite sides of a dielectric light transmitting sheet, and in that behind this sheet is arranged a dielectric marking sheet printed so as to have a plurality of switch identification marks, a reference being arranged in register with each of the capacitors of a group of capacitors belonging to said plurality.

When making switchboards according to the invention, it is possible to obtain a very high level of manufacturing standardization. It is possible to choose an arrangement of switching capacitors such that switching panels to be used with different circuits can all be made identically with regard to their electrodes and the dielectric sheets on which they are deposited. Different marking sheets can be incorporated into the panels according to the wishes of the customers.

Thus, for example, switching capacitors can be arranged in a square matrix. If such a panel is to be incorporated into a telephone set to achieve a proximity keypad, an appropriate identification sheet could be printed with marks representing the ten digits in register with ten of the switching capacitors, and the apparatus manufacturer telephone connections would connect the ten capacitors identified to an appropriate switching circuit. On the other hand, a switching panel comprising an identical arrangement of switching capacitors could be incorporated into a calculator. In this case, the calculator manufacturer may require that the tracking sheet be printed with marks representing the ten digits, the decimal point, and the addition, subtraction, multiplication, division and equality functions. Consequently, the only modification required in the panel manufacturing process for these different destinations is the substitution of the marking sheet, which constitutes a very simple operation.

By an appropriate selection of the arrangement of the capacitors

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any condensation on this face does not affect the proper functioning of the switches.

Fig. 3 illustrates an arrangement in which a panel of sixteen switches is provided with a single terminal 7 for its connection to the potential source. Sixteen input electrodes 3 are connected to this terminal 7 and the sixteen associated output electrodes 4 are connected, by means of conductors 5, to individual terminals 6 for their connection to the control circuit.

The positions of certain control electrodes 11 are indicated in dashed lines.

In fig. 1, a marking sheet 8 made of dielectric material, for example a plastic such as polyethylene terephthalate, is deposited on the first sheet carrying electrodes 1. This sheet has areas bearing marks 9 placed in register with the electrodes 3 , 4. The marking sheet 8 is of smaller dimensions than the first sheet carrying electrodes 1, so as to leave a rebate on its periphery. A second glass sheet 10, transparent and of the same dimensions as the marking sheet 8, is deposited on this sheet so that transparent deposits serving as control electrodes, for example made of doped tin oxide, are placed in register with the pins and the input and output electrodes 3, 4 to form capacitors 12, 13. The rebate formed by the margin of the first sheet and the edges of the marking sheet 8 and of the second carrier sheet electrode 10 receives a bead 14 of adhesive material, to secure the sheets of the panel.

For the use of the switch panel illustrated in fig. 1, the input servo electrodes 3 are connected to a pulse generator, while the output servo electrodes 4 are individually connected to a detection circuit. If a control electrode 11 is touched, or even in certain cases if it is approached sufficiently, for example by means of the finger, the capacitance between the three electrodes will be modified. This will result in a modification of the pulse delivered by the output servo electrode 4. This modification is detected to give a signal, which can be amplified if necessary, to control a switching circuit ensuring the execution of a desired function.

In cases where it is not necessary to touch the electrodes 11, the sheet 10 on which they are deposited can, if desired, be turned over so that the electrodes 11 are located below the surface of the panel.

To deposit a plurality of SnO2 electrodes on a dielectric sheet according to a predetermined design, the following method can be adopted for the manufacture of a proximity effect type switching panel. A silk screen is prepared, and a negative mask made with Wiederhold Wiedoprint Al (trade mark) ink is printed on one side of a glassy or ceramic sheet. The sheet is then conveyed through a heating station, in which the masking ink is cooked and leaves a dry, sticky powdery residue. The sheet is then conveyed to a coating station where it is coated, in a known manner, by spraying with a solution of SnCl4. When the SnCl4 solution comes into contact with the heated sheets, it undergoes pyrolysis to give a uniform coating of SnO 80 mm thick.

After cooling, the mask and the coating of SnO2 which covers it are removed by brushing to leave a positive coating of SnO2 on one face of the sheet. The process is then repeated using another silk screen to form a positive coating of SnO2 on the other side of the same sheet, or on a different sheet if desired, to form the desired arrangement of capacitor.

In a variant of the process, the two faces of a sheet are masked and the sheet is then heated. Coatings of SnO2 are deposited in a single operation on both sides of the sheet, by a high frequency sputtering technique.

Fig. 2 shows a similar panel which has been assembled in a different manner. In this embodiment, the adhesive bead 14 of FIG. 1. In addition, the locating sheet 8 and the second electrode-carrying sheet 10 are laminated one by one.

the other, as well as to the first sheet carrying electrodes 1. This is achieved by means of double-sided adhesive films 15 sold under the trade name Mac Bond.

A panel according to fig. 1 and having an arrangement of capacitive switches as illustrated in FIG. 3 can be used in a calculator in which the various switches can be arranged to display numbers in a display, perform one or more of the four basic arithmetic operations and provide a response. The sixteen capacitive switches can be used for this purpose. The sheet 1 will be larger than that illustrated in FIG. 3, to provide space for a display device. The display device can be mounted on the sheet 1 by any known means.

Fig. 4 illustrates a marking sheet able to be used in a panel intended for such a calculator.

The substrate 8 is made of a transparent plastic film such as a polyester. This film has marks 9 which will be made in different colors or shades of color. The remaining space between the marks 9 and around a section 17 marked display is covered with an opacifying coating. The marks and the opacifying coating are applied to the polyester film by a printing technique such as the offset technique. The plastic film 8 can for example have a thickness of between 50 and 120 μm.

The display section 17 remains transparent. In the calculator, this section must be placed in register with a display device (not shown), while the marks 9 will be in register with the switching capacitors, as described above. In addition, a small portion 16 of the labeling sheet which is to be placed in register with a switching capacitor can remain transparent, if desired, to indicate by means of a light signal that a key has been touched. In the illustrated sheet, only the areas of the marking sheet 8 which are in register with a switching capacitor controlling a function which does not immediately change the display, i.e. the decimal point, the division functions, multiplication, addition and subtraction are provided with such a transparent portion 16. The use of light signals combined with an appropriate circuit for the capacitive switches associated with these marks can thus provide a positive indication that a desired function has actually been entered. . Such a positive indication with respect to the other switches will normally be provided by a change in the display in immediate response to the switch.

A panel as described with reference to figs. 1 and 3 can also be used as a telephone keypad. To this end, only ten of the sixteen switching capacitors will be connected to the external circuit and marked. You can use a marking sheet like the one illustrated in fig. 4, but in which only the marks 9 appear corresponding to the numbers 1 to 9 and 0. These marks will be placed in register with the selected switching capacitors. The area around the marks 9 corresponding to the ten digits is opacified as described above. The remaining electrode sets are not connected to the circuit and therefore do not form active switches. As the electrodes consist of a transparent coating, the non-selected switching capacitors will in practice be barely visible to the user, since they are not identified. Obviously, if one wishes to provide additional commands such as entering and reading from a coded memory of frequently used telephone numbers, recalling an operator, switching to an extension, sets of electrodes additional will be connected to corresponding external circuits. These sets of electrodes will also be provided with appropriate marks.

In such a variant, the display device 17 could sometimes be omitted. In this case, it would be better to provide a light transmitting area such as 16 in register with each selected switching capacitor.

From the comparison of these two examples of use, it will appear that the same grid of electrodes was used for the manufacture

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switching, it is possible, from a standard production, to obtain switching panels comprising fractions or multiples of a number of capacitors deposited in a standardized manner. This can be achieved by dividing a standard panel or by juxtaposing two or more of these panels, as appropriate. In each case, it is easy to adapt the tracking sheets to customer requirements.

Another advantage of using marking sheets separate from the sheets carrying the capacitors is that the application of the marks does not interfere with the method of depositing the electrodes.

In preferred embodiments of the invention, at least one of the capacitors comprises two servo electrodes, in this case an input servo electrode and an output servo electrode. This simplifies the required switching circuit.

According to a second aspect of the invention, a proximity effect type switching panel, comprising a plurality of capacitors each comprising a control electrode and at least one relay electrode arranged in capacitive relationship, is characterized in that the electrodes control and relay elements are arranged, respectively, on front and rear dielectric sheets, at least the front sheet and the light-transmitting control electrodes, and in that between the front and rear sheets is sandwiched a sheet marking dielectric carrying a plurality of switch identification marks, such marks being arranged in register with at least some of the capacitors of a group of capacitors belonging to said plurality of capacitors.

In addition to the advantages listed above with respect to the first aspect of the invention, a panel according to the second aspect of the invention also has the advantage of easier manufacture, because the electrodes can be deposited on the same face of their respective sheet.

In embodiments of the invention according to the second aspect, the marks can be applied to the marking sheet in any suitable manner. However, it is preferred that the registration sheet is obtained by printing.

The deposition of the control electrodes of a panel according to the second aspect of the invention is simplified when they are deposited on the same face of a sheet, as is preferred.

In certain embodiments of either aspect of the invention, each capacitor includes a single servo electrode to be connected to the switching circuit. However, in preferred embodiments relating to both the first aspect and the second, each or at least some of the capacitors have two servo electrodes, in this case an input servo electrode and a servo electrode Release.

In embodiments of the second aspect of the invention, all the input servo electrodes are preferably deposited on the same face of a sheet. Likewise, all the output servo electrodes are preferably deposited on the same face of a sheet.

In certain preferred embodiments of the second aspect of the invention, the input servo electrodes and the output servo electrodes are deposited on at least two different sides of the sheet. Such faces can be the opposite faces of the same sheet, or faces of two or more different sheets. This facilitates the arrangement of the conductors connected to the electrodes.

In other preferred embodiments of the second aspect of the invention, all the servo electrodes are deposited on the same face of a sheet. This arrangement has the advantage that all the electrodes can be produced in a single operation.

In other embodiments of the second aspect of the invention, it is preferred that all the electrodes and all the sheets on which they are deposited transmit light. This makes the sheets carrying the electrodes suitable for incorporating them into a switching panel with a marking sheet having at least one part transmitting light in register with a capacitor. This provides an indication of the operation of the switching capacitor by means of a light source which can be arranged behind the panel.

In certain preferred embodiments of one or other aspect of the invention, said marking sheet has at least one portion transmitting light in register with a capacitor.

As a variant or in addition, said marking sheet comprises a display zone transmitting light. This arrangement is particularly advantageous in the cases, for example, of calculators and telephone keyboards associated with a coded memory. In such cases, a display device can be placed behind the panel to display the sequence of a calculation or a telephone number recalled from memory, as the case may be.

Advantageously, the or at least one sheet carrying electrodes is a glass sheet.

The marking sheet is preferably a plastic sheet, for example a polyester such as polyethylene terephthalate. The labeling sheet preferably has a thickness of between 50 and 120 µm. This order of magnitude meets the requirements of the usual printing techniques, and the proper functioning of the capacitive switches is not disturbed when the marking sheet is placed between the sheets carrying the electrodes.

Preferably, each electrode is formed by a coating of Sn02 or ln203 optionally doped to improve its conducti-vity. Such coatings can be hard and resist abrasion, while being substantially transparent.

In order to avoid parasitic switching, it is advantageous to place a screen electrode behind the electrodes.

In certain preferred embodiments of the invention, the sheets of the panel are laminated together. This can be done advantageously by means of a double-sided adhesive film. As a variant or in addition, a sheet of the panel is larger than the other sheets which are joined thereto, so as to leave a rebate which receives a bead of adhesive material sealing together the sheets of the panel.

Preferred embodiments will now be described in more detail, by way of examples, with reference to the appended drawings in which:

fig. 1 and 2 are cross sections of two embodiments of the invention;

fig. 3 is a plan view of an insulating substrate carrying input and output electrodes;

fig. 4 is a plan view of a marking sheet which is used with a switching panel comprising the substrate of FIG. 3, and FIGS. 5 and 6 are partial sections of a third and a fourth embodiment of the invention.

In fig. 1, a glass sheet 1 carries, if desired, a coating of tin oxide 2, applied to the entirety of one of its faces, serving as screen electrode. It carries on its other face two pairs of servo electrodes, each pair consisting of an input electrode 3 and an output electrode 4. These electrodes also consist of tin oxide, doped if necessary. The output electrodes 4 are individually connected by conductors 5 (which may also consist of tin oxide) to terminals 6, each of which is formed by an enamel applied to an end portion of the conductor 5. The terminals 6 are located on the side edges of the panel for their connection to the associated external circuit. The input electrodes 3 are connected to a common source of potential (not shown).

The face of the substrate which carries the servo electrodes 3, 4 may possibly be covered with a thin transparent plastic film, for example applied by spraying, to prevent

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Signs. A standardized process can be used to deposit the electrodes on their substrates. This has a particular advantage when a coating is deposited by pyrolysis of a metal compound on a hot substrate such as hot glass. Process control is simplified. Only the marking sheet must be substituted 5 in the panel. As these marking sheets are obtained by a printing technique, it is very easy to modify the marks as regards their location, their color, their shape, etc.

without modifications affecting the more complicated method of depositing the electrodes, as would have been the case if the marks had had to be applied to one of the sheets carrying the electrodes.

Fig. 5 illustrates another modification of the embodiments illustrated in FIGS. 1 and 2, in which similar reference numbers have been given to similar elements. The main difference between the embodiments of Figs. 1 and 5 is that, in fig. 5, the input servo electrodes 3 are deposited on a surface of a sheet 1A which is different from the surface on which the output servo electrodes 4 are deposited. In FIG. 5, the sheet 1A is a sheet of glass of intermediate size which is placed between the sheet 1 on which are deposited the output servo electrodes and the marking sheet 8. The input servo electrodes 3 are connected to a common terminal 7.

The sheets of the switch panel of fig. 5 can be joined by a bead of adhesive similar to that shown in 14 in FIG. 1 and / or using three sheets of double-sided adhesive film (see film 15 in fig. 2).

Fig. 6 illustrates an embodiment of the invention in which all the electrodes 3, 4, 11 are carried by the same dielectric sheet 10, which is constituted by a sheet of clear glass. As before, the output servo electrodes 4 are connected by conductors 5 to terminals 6 on the sides of the panel but, in this case, these conductors and the terminals are applied to the glass substrate 10. A marking sheet 8 bearing printed marks 9 is laminated to the glass sheet 10 by an adhesive film 15. A support sheet 18 is in turn laminated to the marking sheet 8, again by an adhesive film 15.

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Claims (15)

646,824 1. Proximity effect type switching panel comprising a plurality of capacitors each comprising a control electrode and at least one relay electrode arranged in capacitive relationship, characterized in that said control (11) and relay (3) electrodes , 4) are light transmitting elements deposited on the opposite sides of a light transmitting dielectric sheet (10), and in that behind this sheet is arranged a dielectric marking sheet (8) printed so as to present a plurality of switch identification markers (9), a marker being arranged in register with capacitors (12, 13) of a group of capacitors belonging to said plurality. 2. Switching panel of the proximity effect type comprising a plurality of capacitors each comprising a control electrode and at least one relay electrode arranged in capacitive relationship, characterized in that the control and relay electrodes are arranged, respectively, on front (10) and rear (1, 1 A) dielectric sheets, at least the front sheet (10) and the control electrodes (11) transmitting light, and in that between the front sheets (10) and rear (1, 1A) is sandwiched with a dielectric marking sheet (8) carrying a plurality of marks (9) for identifying the switch, such marks being arranged in register with at least some of the capacitors (12 , 13) of a group of capacitors belonging to said plurality of capacitors. 2 3. Panel according to claim 1, wherein at least one of the capacitors (12,13) comprises two relay electrodes (3,4). 4. Panel according to claim 2, wherein the marking sheet (8) is obtained by printing. 5. Panel according to one of claims 2 or 4, wherein all the control electrodes (11) are deposited on a single face of a sheet (10). 6. Panel according to one of claims 2,4 or 5, wherein each of the capacitors (12, 13) comprises two servo electrodes (3, 4), namely an input servo electrode (3) and an output servo electrode (4). 7. Panel according to one of claims 2 or 4 to 6, in which all of the relay electrodes (3, 4) are deposited on the same face of a sheet (1). 8. Panel according to one of claims 2 or 4 to 7, wherein all the electrodes (3, 4, 11) and all the sheets (1, 1A, 10) on which they are deposited transmit light. 9. Panel according to one of claims 1, 3 or 8, wherein said marking sheet (8) has at least one light-transmitting portion (16), in register with a capacitor (12, 13). 10. Panel according to one of claims 1, 3, 8 or 9, wherein said marking sheet comprises a display area transmitting light (17). 11. Panel according to one of claims 1 to 10, wherein said marking sheet (8) is a plastic sheet, such as a polyester sheet. 12. Panel according to one of claims 1 to 11, wherein the marking sheet has a thickness between 50 and 120 µm. 13. Panel according to one of claims 1 to 12, wherein the constituent sheets (1, 1A, 8, 10) are laminated together. 14. The panel of claim 13, wherein the laminating is carried out by means of a double-sided adhesive film (15). 15. Panel according to one of claims 1 to 14, wherein a sheet (1) of the panel is larger than the other sheets (8, 10) which are integral therewith, so as to leave a rebate which receives a bead of adhesive material sealing together the sheets of the panel.