Eds switch array and logic

(74) Agent: Dominique Pintaud, Department of Industrial Property, IBM.

© Set of elastic diaphragm switches and associated logic circuits.

72) Invention by: Fritz S. Wiedmer.

33) (32) (31

Conventional priority: Patent application filed in the United States of America on July 13, 1970, n. 54.300 in the name of Fritz S. Wiedmer.

> Sale of booklets to I IMPRIMERIE NATIONALE. 27, rue de la Convention - PARIS (15^e)

23162

The present invention relates to electrical switching elements for generating an exit code, and more particularly to a set of pressure-actuated elastic diaphragm switching elements, connected on both sides of a wiring panel to output pins as well as a logic allowing to detect the simultaneous pressing of two keys, and to verify the existence of an electrical contact between the diaphragm and all the switching elements of the same assembly.

□ years the patent n ° 1 471 629 filed in France by the plaintiff on March 17, 1966 is described a switching device comprising a diaphragm covered with a layer of elastomeric material and supported by an incompressible layer; when pressure is applied to the elastomeric material, the latter and the diaphragm are deformed so that terminals are brought into contact with each other. At least two embodiments are described in th e aforementioned patent; the first comprising strips of conductive material oriented perpendicularly to each other, the switching contacts being located in the matrix assembly; and the second comprising an assembly produced by covering the entire lower part of the diaphragm with a conductive material or by using a diaphragm in conductive material and by providing an individual conductive segment for each key position. In this latter embodiment, a single conductor is connected to the conductive layer located under the diaphragm and an individual output conductor is provided for each segment. In this way, each key position must be determined by decoding the XY coordinates. It then becomes necessary, if an exit code is desired, to provide a logic making it possible to decode the key position for a given XY coordinate.

Another keyboard known in the prior art comprises a binary coding device comprising a key which selectively interconnects different conductors or electrical circuits which are printed or arranged in parallel on a flat base element. Each key has a number of metal bars closing or shorting circuits and on which irregularly spaced and protruding contact elements are arranged which, when selectively actuated, pass the current through a plurality of parallel conductors . A serious drawback of this device is the number of output pins that can be used, that is to say that a conductor for each output pin must pass under each key position, without however these conductors being brought together. to each other to such an extent that the shorting bars cannot establish separate contact with the different conductors.

23162

One of the objects of the present invention is therefore to provide an improved electrical switching element actuated by pressure.

Another object of the invention is to provide an improved diaphragm switching element which can be actuated by pressure.

Another object of the invention is to provide an improved diaphragm switching device which can be actuated by pressure and which has switching elements connected on both sides of a wiring panel to output pins in order to directly produce a code for output without decoding or coding logic.

Another object of the invention is to provide an improved keyboard with electrical diaphragm switching comprising a so-called contact verification logic making it possible to verify whether all the switching elements have established electrical contact with the diaphragm.

Another object of the invention is to provide an improved keyboard with elastic diaphragm 15 comprising a logic known as simultaneous key depression detection, making it possible to verify that a single key is pressed during the transmission of the exit code .

The present invention achieves the above objectives using an electronic switching device comprising at least one button d_e button, an elastic diaphragm, dividers and a wiring panel. The latter consists of a substrate and at least one set of switching elements. Switching elements are electrically connected by wiring on both sides of the substrate to output pins. The elastic diaphragm consists of a thin continuous sheet of conductive and elastic material which can be changed by the button by means of the separating elements so as to establish electrical contact with the set of switching elements. . The wiring carried out on both sides of the substrate makes it possible to connect the switching elements to the output pins so as to directly generate the output code from the set of switching elements. The simultaneous key press detection logic detects simultaneous electrical contacts that may occur between the diaphragm and different switching elements of different sets. Similarly, the contact verification logic makes it possible to detect the electrical contact which could occur between the diaphragm and all the switching elements of the same assembly.

Other objects, characteristics and advantages of the present invention will emerge more clearly from the description which follows, made with reference to the drawings annexed to this text, which represent a preferred embodiment of the latter.

Figure 1 shows a section of the button, the diaphragm

23162 electrical, separation elements and the wiring panel used in the keyboard of the present invention.

Figure 2A shows the configuration of switching elements and conductors on the top of the wiring panel.

FIG. 2B shows the configuration of conductors on the lower part of the wiring panel, the black dots indicating connection holes making it possible to interconnect the conductors of the upper and lower parts of the panel.

FIG. 2C represents a logic diagram of the circuits necessary for the purposes of detecting simultaneous pressing of keys and of verifying the contacts of the code generated at the output pins of FIGS. 2A and 2B.

FIG. 3 represents the wiring panel of a ten-key keyboard using a code 3 of 14 and the associated logic for checking electrical contact and detecting simultaneous pressing of keys.

FIG. 4A represents the wiring panel for a ten-key keyboard and the associated logic for checking contact and detecting simultaneous pressing of keys to generate an EBCDIC code.

Figure 4B shows in more detail the data selector / multiplexer (DS / ΓΙ) of Figure 4A.

A description is given below with the aid of FIG. 1 of the button with elastic diaphragm switching comprising the button 4D, the diaphragm 51 and the wiring panel 60.

The button button (or actuating device) 40 is a round button whose FIG. 1 represents a section. The part 41 of the button touched by the operator's finger is concave in the figure, but can also be convex or flat, pressed into the upper plate 30, at the same level or above it. The outside diameter or sliding surface 42 of the button 40 moves inside the hole 31 in the plate 30. The hole 31 also includes a conical area 32, a flange 33 and a surface 34 of a larger diameter. The conical zone 32 makes it possible to reduce the contact zone between the hole 31 and the button 40, the flange 33 prevents the button 40 from moving upwards and out of the hole 31.

The button 40 also comprises an O-ring part 44 having a groove 43 in which the dust, etc., which can fall between the hole 31 and the surface 42 of the button can deposit. The toroidal part 44 has the shape of a spherical ball when viewed in the manner indicated in FIG. 1 in order to allow the button 40 to pivot only around the center of the part 44 and to prevent any seizure from occurring. the surface 42 of the button and the surface of the hole 31. The lower surface of the O-ring part 44 includes a stop surface 45 for the actuation section 46 of the button intended

23162 preventing the diaphragm 51 from being damaged and providing the desirable dB force / displacement characteristics for the actuating section 46.

The actuating section 46 extends over a distance W below the surface of the annular abutment 45 and its action, combined with that of the abutment, provides reliable or reproducible actuation of the elastic diaphragm independently of the force applied by the keyboard operator's fingers.

The separating element 50, which also functions as a force distributor, protects the elastic diaphragm against sudden contact with the actuating section 46 and against irregularities in the surface thereof. The fact that the penetration of the actuating section 46 into the separating element 50 is limited by the surface 45 constitutes additional protection of the diaphragm 51 in the event of violent, accidental or desired depression of the button 40.

The actuating section 46 plays an important role in determining the force / displacement characteristics. The length W determines the stroke of the button and its diameter, as well as the thickness and the hardness of the separating layer 50, determines the actuation force of the button. A flexible and thick layer 50 therefore gives a long stroke of the button, and vice versa. In general, the flexibility and thickness of the element and the dimension W should be increased or decreased together. Nais a precise relative selection allows a light button to have a long stroke, or allows a button having any stroke to give a touch¹* harder or lighter. The shape of the actuation section

46 (i.e. the fact that its lower part is round or flat) affects the force / displacement characteristics of the button evenly, and the same applies to the physical characteristics of the elastic diaphragm and the other separation layers 52. Finally, another function of the separating layer 50 is to apply to the diaphgrame 51 a force which extends from the center (that is to say from the axis of the button 40) towards the edges on a well defined length of the button movement while increasing the actuating force from the center to the edges.

A key button 40 of the type shown in the figure, with an actuating section 46 and an annular stop 45, used in conjunction with _Une separation layer 50 relatively thick and flexible, allows to obtain a reliable operation of the key it also includes a separation layer 52 having an opening V through which the elastic diaphragm 51 is brought into contact by pressure with the set of switching elements arranged on the upper surface of the wiring panel 60.

The upper and lower surfaces of the panel 60 have strips

23162 conductive and connection holes for interconnecting these conductive strips, as described below.

The insulation layer 53 isolates the wiring panel from the bottom plate 54. The various elements 50, 51, 52, 60, 53 and 54 can simply be placed one above the other and kept at the same place. using screws or any other suitable mechanical device.

The diaphragm 51 consists, for example, of an elastic alloy of copper and beryllium with a thickness of 0.013 to 0.025mm on which a layer of gold with a thickness of 3.8 microns is plated. Increasing the proportion of copper in the alloy has minimal effect on the actuating force of the switch. The actuation force is determined by the combination of the distribution-actuation elements and the thickness of the separation layers.

The separating layer 52 consists of Mylar with a thickness of 0.051 to 0.076mm, this latter thickness being preferred since it tends to make the switch less sensitive to imperfections on the lower surface of the diaphragm 51. Such a layer of 0.076mm of thickness comprising a hole of approximately 63 mm, a sensitive switch which keeps the stresses exerted on the diaphragm 51 at a low value.

The wiring panel 60 is constituted by a substrate made of epoxy material covered with copper. The insulation layer 53 is constituted, for example, by Mylar with a thickness of 0.076 mm, which is obviously not necessary if the lower plate 54 is not conductive. The purpose of the plate 54, the use of which is optional, is to reinforce the panel 60 and to protect it from possible damage.

A preferred embodiment of the electric diaphragm switching keyboard of the present invention is described below using FIGS. 2A and 2B. FIG. 2A represents a configuration of printed circuits on the Y side of a wiring panel (see FIG. 1) which will come into contact with the elastic diaphragm. Figure 2B shows a configuration of conductors on the Z side of the panel (see Figure 1). FIGS. 2A and 2B are seen from the same position, the output pins 61 to 68 having the same orientation in the two figures. Each key position is shown in Figure 2A by a set of four squares which are the switching elements. The bold lines represent the conductors, and the dots represent the connection holes for connecting the conductors of Figure 2B with the conductors or the switching elements of Figure 2A. The four switching elements corresponding to each key position are electrically isolated from each other The upper right square represents bit position 8, the lower square

23162 right bit position 4, the upper left square bit position

2, and the lower left square bit position 1. The upper right square of each key position is connected to either the output pin

68, or at the output pin 70; the lower right square is connected either to the output pin 64 or to the output pin 74s the upper left square is connected to either the output pin 62 or to the output pin 72, and the lower left square is connected either to the output pin 31 or to the output pin 71. The output pin 63 is connected to the region 73 which is kept in permanent contact with the electric diaphragm. Table 1 below shows the interconnections made via each connection hole V1 to V57. The right column of the table relates to the conductor located on the lower part of the panel and represented in FIG. 2B. The central column indicates the conductor or the switching element located on the upper part of the panel and which is connected via the connection hole to the corresponding conductor on the lower part of the panel. The central column is interpreted as follows: when a connection hole is followed by an asterisk (for example V-13, V16), this means that the connection concerns a conductor at the top of the panel (for example 62a ,

72a). The connections made through the other holes relate to one of the switching elements of each key position; for example, the connection hole V1 makes it possible to make a connection with the key position D, square 2; the V-2 connection hole allows connection with the D key position, square 1, etc.

²⁵ TABLE 1

<td> 30</td><td>Connection hole</td><td>Superior connection (conductor or switching element)</td><td>Sign in Lower (driver)</td>

<td></td><td>V1</td><td>BD2</td><td>72b</td>

<td></td><td>V2</td><td>BD1</td><td>71b</td>

<td></td><td>V3</td><td>0B2</td><td>72b</td>

<td></td><td>V4</td><td>BB1</td><td>71b</td>

<td> 35</td><td>V5</td><td>ΘΖ2</td><td>72b</td>

<td></td><td>V6</td><td>ΘΖ1</td><td>71b</td>

<td></td><td>V7</td><td>BN2</td><td>72b</td>

23162

<td> 5</td><td>Connection hole</td><td>Superior connection (conductor or switching element)</td><td>Sign in Lower (driver)</td>

<td></td><td>VS</td><td>8N1</td><td>61b</td>

<td></td><td>V9</td><td>8B4</td><td>74b</td>

<td></td><td>V10</td><td>8Z4</td><td>74b</td>

<td> 10</td><td>V11</td><td>8M2</td><td>72b</td>

<td></td><td>V12</td><td>8M1</td><td>61b</td>

<td></td><td>V13 *</td><td>62a</td><td>62b</td>

<td>XK</td><td>V14</td><td> 872</td><td>62b</td>

<td></td><td>V15—</td><td> 871</td><td>61b</td>

<td></td><td> *</td><td></td><td></td>

<td></td><td>V1B</td><td>72a</td><td>72b</td>

<td> 15</td><td>V17</td><td> 882</td><td>72b</td>

<td></td><td>V1S</td><td> 881</td><td>71b</td>

<td></td><td>V19 *</td><td>71a</td><td>71b</td>

<td></td><td>V20</td><td> 892</td><td>72b</td>

<td>XK</td><td>V21</td><td> 891</td><td>61b</td>

<td> 20</td><td>V22</td><td>8M8</td><td>68b</td>

<td>I</td><td>V23</td><td> 888</td><td>68b</td>

<td>I</td><td>V24</td><td> 898</td><td>68b</td>

<td></td><td>V25</td><td>8E2</td><td>62b</td>

<td></td><td>V2B</td><td>8E1</td><td>71b</td>

<td> 25</td><td>V27 *</td><td>62a</td><td>62b</td>

<td></td><td>V28</td><td> 842</td><td>72b</td>

<td></td><td>V29</td><td> 841</td><td>71b</td>

<td></td><td>V30 *</td><td>62a</td><td>62b</td>

<td></td><td>V31 *</td><td>72a</td><td>72b</td>

<td> 30</td><td>V32</td><td> 852</td><td>72b</td>

<td></td><td>V33</td><td> 851</td><td>61b</td>

<td></td><td>V34 *</td><td>71a</td><td>71b</td>

<td></td><td>V35</td><td> 862</td><td>62b</td>

<td></td><td>V36</td><td> 861</td><td>71b</td>

<td> 35</td><td>V37</td><td>8E4</td><td>64b</td>

<td></td><td>V38</td><td> 844</td><td>64b</td>

<td></td><td>V39</td><td> 854</td><td>64b</td>

<td></td><td>V40</td><td> 864</td><td>64b</td>

<td></td><td>V41</td><td>8R2</td><td>62b</td>

23162

<td> 5</td><td>Connection hole</td><td>Superior connection (conductor or switching element)</td><td>Sign in Lower (driver)</td>

<td></td><td>V42</td><td>8R1</td><td>61b</td>

<td></td><td>V43</td><td> 812</td><td>72b</td>

<td></td><td>V44</td><td> 811</td><td>61b</td>

<td></td><td>V45 *</td><td>72a</td><td>72b</td>

<td> 10</td><td>V46 *</td><td>62a</td><td>62b</td>

<td></td><td>V47</td><td> 822</td><td>62b</td>

<td></td><td>V48</td><td> 821</td><td>71b</td>

<td></td><td>V49 *</td><td>71a</td><td>71b</td>

<td></td><td>V50</td><td> 832</td><td>62b</td>

<td> 15</td><td>V51</td><td> 831</td><td>61b</td>

<td></td><td>V52</td><td>8R4</td><td>64b</td>

<td></td><td>V53</td><td> 818</td><td>78b</td>

<td></td><td>V54</td><td> 828</td><td>78b</td>

<td></td><td>V55</td><td> 824</td><td>74b</td>

<td> 20</td><td>V56</td><td> 838</td><td>78b</td>

<td></td><td>V57</td><td> 834</td><td>74b</td>

The keyboard exit code in Figure 2 is described below using Figures 2A and 2B. A 16-key keyboard with hexadecimal output values ​​zero through F is shown in these figures.

The different keys are: SB, B1, 02, 83, 84, 85, 88, 87, 88, 89, 8Z,

ΘΝ, 8D, ΘΜ, 8E, 8R. The binary value appearing at the output pins 6Z1-678, is indicated in the right column of table 2 below. For example, a zero in column ”8” indicates positive logic at the spindle

78j a 1 in column β represents a positive logic at pin '30 68} a zero in column 4 indicates a positive logic at pin

74} a 1 in column A a positive output on line 64, a zero in column 2 * represents a positive logic level at the output pin 72} a 1 in column 2 represents a positive logic level at pin 62j a zero in column I represents a positive logic level at output pin 71 * and a 1 in column 'Ί ”represents a positive logic level at output pin 61.

By pressing the D key to bring the elastic diaphragm into contact with the set of switching elements 80, the hexadecimal exit code zero will be detected as a positive logic level at the output pins

71, 72, 74 and 78, and as a negative logic level at the output pins

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61, 62, 64 and 66. Similarly, by putting the key 65 in contact with the diaphragm, a hexadecimal output 5 is detected as a positive logic level at the output pins 64 and 61, and 76 and 72.

TABLE 2

<td rowspan="2">Touch</td><td rowspan="2">Output hexadecimal value</td><td colspan="4">Binary output value</td>

<td> 8</td><td> 4</td><td> 2</td><td> 1</td>

<td>8B</td><td> 0</td><td> 0</td><td> 0</td><td> 0</td><td> 0</td>

<td> 81</td><td> 1</td><td> 0</td><td> 0</td><td> 0</td><td> 1</td>

<td> 82</td><td> 2</td><td> 0</td><td> 0</td><td> 1</td><td> 0</td>

<td> 63</td><td> 3</td><td> 0</td><td> 0</td><td> 1</td><td> 1</td>

<td> 64</td><td> 4</td><td> 0</td><td> 1</td><td> 0</td><td>Q</td>

<td> 85</td><td> 5</td><td> 0</td><td> 1</td><td> 0</td><td> 1</td>

<td> 86</td><td> 6</td><td> 0</td><td> 1</td><td> 1</td><td> 0</td>

<td> 87</td><td> 7</td><td> 0</td><td> 1</td><td> 1</td><td> 1</td>

<td> 88</td><td> 8</td><td> 1</td><td> 0</td><td> 0</td><td> 0</td>

<td> 89</td><td> 9</td><td> 1</td><td> 0</td><td> 0</td><td> 1</td>

<td>8Z</td><td>AT</td><td> 1</td><td> 0</td><td> 1</td><td> 0</td>

<td>8N</td><td>B</td><td> 1</td><td> 0</td><td> 1</td><td> 1</td>

<td>8D</td><td>VS</td><td> 1</td><td> 1</td><td> 0</td><td> 0</td>

<td>8M</td><td>D</td><td> 1</td><td> 1</td><td> 0</td><td> 1</td>

<td>8E</td><td>E</td><td> 1</td><td> 1</td><td> 1</td><td> 0</td>

<td>8R</td><td>F</td><td> 1</td><td> 1</td><td> 1</td><td> 1</td>

It follows from the above that the desired hexadecimal exit code is obtained directly at output pins 61 to 78. The circuits necessary for the purposes of checking electrical contact and detecting simultaneous pressing of keys already mentioned are described below. -after using Figure 2C. This figure shows the output pins 61 to 78 of Figures 2A and 2B. Output pin 61 is connected to the exclusive OR circuit

11. The output pin 71 is connected to the exclusive OR circuit 11 and to the AND circuit 16. The output pin 62 is connected to the exclusive OR circuit

12. The output pin 72 is connected to the exclusive OR circuit 12 and to the AND circuit 17. The output pin 64 is connected to the exclusive OR circuit

13. The output pin 74 is connected to the exclusive OR circuit 13 and to the AND circuit 18. The output pin 68 is connected to the exclusive OR circuit

14. The output pin 76 is connected to the exclusive OR circuit 14 and to the AND circuit 19. The outputs of the exclusive OR circuits 11 to 14 are connected i

I

23162 to AND circuit 15, the output of which is connected to AND circuits 16 to 19.

The inputs of the AND circuit 15 coincide so that the output of this circuit is at a positive logic level only if the output of each exclusive OR circuit 11 to 14 is positive. This only occurs when one, and only one, of the following pairs of output pins is positive:

and 71, 62 and 72, 64 and 74, and 66 and 76. A positive output from the AND circuit 15 therefore indicates that only one of the keys of the keyboard of FIG. 2A has been pressed. The voltage levels of pins 56 to 659 are decoded directly so as to obtain the binary values ​​in table 2.

The wiring board for the 10-key keyboard using a code known as 3 of 14 as well as the associated logic for checking electrical contact and detecting simultaneous pressing of keys, are described below using FIG. 3. The connection elements A, B and C of the keys 90 to 99 are wired as described above and connected to the output pins 2A0 to 2C3. For the sake of clarity, only the 10 keys 90 to 99 of the numerical part of a much larger keyboard are indicated on the diagram, but the logic of the entire keyboard is shown.

The solid lines and dotted lines represent the connections between the keys 90 to 99 and the output pins 2A0 to 2C3, the dotted lines referring to one side of the wiring panel and the solid lines to the other side. of the panel. Other cabling systems can obviously be used to connect the different switching elements A, B and C to the output pins 2A0 to 2C3. The points indicated in the figure at the meeting points of the dotted lines and solid lines, or at the points where the dotted lines are connected to the switching elements of the different keys, represent the connection holes, however, the dots between the solid lines and the switching elements simply indicate connections between the conductors of the printed circuit configuration and the switching elements which are on the same side of the wiring panel. Here, all output pins 2A0 to 2C3 are connected to a positive voltage source. The elastic diaphragm is grounded and is shown as being element 51A.

The logic for detecting simultaneous key presses, which is described in more detail below, consists of inverters 431 to 444, AND circuits 451 to 454, OR circuits 465 to 467, and AND circuit 468. The exit code 3 of 14 which is generated by pressing one of the keys 90 to 99 appears directly at the output pins 2A0 to 2C3, however that a signal present on pin 470 indicates that only one key has been pressed and that all the switching elements of this key

23162 came into contact with diaphragm 51A, indicating that a valid code exists at output pins 2A0 to 2C3.

The exit code generated by the keys 90 to 99 at the output pins 2A0 to 2C3, as well as the logic circuits of FIG. 3, are successively described below.

It will first be noted that the switching element A of each of the keys 90 to 99 is connected to only one of the output pins 2A0 to 2A4; that the switching element S of each of the keys 90 to 99 is connected only to one of the output pins 2B0 to 2B4; and that finally the switching element C of each of the keys 90 to 99 is connected to only one of the output pins 2C0 to 2C3. Pressing the key, for example, 90 causes the appearance of a positive logic signal at the output pins 2B2, 2A4 and 2C0. Table 3 below shows the output pins 2A0 to 2C3 to which the switching elements of each key are connected.

TABLE 3

<td>Touch</td><td>Switching element associate</td><td>Output pin correspondent</td>

<td> 90</td><td>90A</td><td>2A4</td>

<td></td><td>90B</td><td>2B2</td>

<td></td><td>90C</td><td>2C0</td>

<td> 91</td><td>91A</td><td>2A1</td>

<td></td><td>91B</td><td>2B1</td>

<td></td><td>91C</td><td>2C0</td>

<td> 92</td><td>92A</td><td>2A1</td>

<td></td><td>92B</td><td>2B2</td>

<td></td><td>92C</td><td>2C0</td>

<td> 93</td><td>93A</td><td>2A1</td>

<td></td><td>93B</td><td>2B3</td>

<td></td><td>93C</td><td>2C0</td>

<td> 94</td><td>94A</td><td>2A2</td>

<td></td><td>94B</td><td>2B2</td>

<td></td><td>94C</td><td>2C0</td>

<td> 95</td><td>95A</td><td>2A2</td>

<td></td><td>95B</td><td>2B2</td>

<td></td><td>95C</td><td>2C0</td>

23162

<td>Touch</td><td>Switching element associate</td><td>Output pin correspondent</td>

<td> 96</td><td>96A</td><td>2A2</td>

<td></td><td>96B</td><td>2B3</td>

<td></td><td>96C</td><td>2C0</td>

<td> 97</td><td>97A</td><td>2A3</td>

<td></td><td>97B</td><td>2B1</td>

<td></td><td>97C</td><td>2C0</td>

<td> 90</td><td>9ΘΑ</td><td>2A3</td>

<td></td><td>9ΘΒ</td><td>2B2</td>

<td></td><td>98C</td><td>2C0</td>

<td> 99</td><td>99A</td><td>2A3</td>

<td></td><td>99B</td><td>2B3</td>

<td></td><td>99C</td><td>2C0</td>

He reassures from the above that the fact of actuating, for example, the key 90 produces an exit code constituted by positive logic signals at the output pins 2A4, 2B2 and 2C0. Similarly, the fact of pressing the key 94 causes the appearance of an exit code in the form of contact closings to pins 2A2, 2B2 and 2C0.

The logic circuit of Figure 3 is described below. The output pin 2A0 is connected to the inverter 431 and to the AND circuits 452 to 455.

The output pin 2A1 is connected to the inverter 432 and to the ET circuits 451, 453, 454 and 455. The output pin 2A2 is connected to the inverter 453 and to the ET circuits 451, 452, 454 and 455. The pin output 2A3 is connected to the inverter 434 and to the AND circuits 451, 452, 453 and 455. The output pin 2A4 is connected to the inverter 435 and to the AND circuits 451 to 454.

The output pin 2B0 is connected to the inverter 436 and to the ET circuits 457 to 460. The output pin 2B1 is connected to the inverter 437 and to the ET circuits 456, 458, 459 and 460. The output pin 2B2 is connected to the inverter 436 and to the ET circuits 456, 457, 459 and 460. The output pin 2B3 is connected to the inverter 439 and to the ET circuits 456. 457,

456 and 460. The output pin 2B4 is connected to the inverter 440 and to the ET circuits 456 to 459.

The output pin 2C0 is connected to the inverter 441 and to the circuits

ET 462 to 464. The output pin 2C1 is connected to the inverter 442 and

23162 to circuits ET 461, 463 and 464. The output pin 2C2 is connected to the inverter 443 and to circuits ET 461, 462 and 464. The output pin

2C3 is connected to the inverter 444 and to the AND circuits 461 to 463.

The inverter 431 is connected to the AND circuit 451, the inverter 432 to the AND circuit 452, the inverter 433 to the AND circuit 453, the inverter 434 to the AND circuit 454, the inverter 435 to the AND circuit 455, the inverter 463 to the ET circuit 456, the inverter 437 to the ET circuit 457, the inverter 438 to the ET circuit 458, the inverter 439 to the ET circuit 459, the inverter 440 to the ET circuit 460, the inverter 441 to the ET circuit 461 , the inverter 442 in the AND circuit 462, the inverter 443 in the AND circuit 463, and the inverter 444 to the AND circuit 464. The inputs of the OR circuit 465 are the outputs of the AND circuits 451 to 455, the inputs of the OR circuit 466 are the outputs of the AND circuits 456 to 460, and the inputs of the OR circuit 467 are the crimp of the AND circuits 461 to 464. The outputs of the OR circuits 465 to 467 are transmitted to the AND circuit 468, the output of which appears at pin 470. The appearance of a signal at pin 470 indicates that good electrical contact exists between the diaphragm and the various switching elements, and also indicates that a single key has been pressed.

A description is given below, using FIG. 4A, of a keyboard and of the logic making it possible to generate an EBCDIC code in which each switching element of each key determines two bits in the output code. in accordance with the table below:

TABLE 4

<td rowspan="3">Touch</td><td colspan="4">Element output pins</td><td colspan="4">Exit Codes</td>

<td rowspan="2">AT</td><td colspan="3">of commutation</td><td rowspan="2">AT 12</td><td rowspan="2">B 34</td><td rowspan="2">vs 56</td><td rowspan="2">D 78</td>

<td>B</td><td>VS</td><td>D</td>

<td> 20</td><td>1A3</td><td>1B3</td><td>1C0</td><td>1D0</td><td> 11</td><td> 11</td><td> 00</td><td> 00</td>

<td> 21</td><td>1A3</td><td>1B3</td><td>1C0</td><td>1D1</td><td> 11</td><td> 11</td><td> 00</td><td> 01</td>

<td> 22</td><td>1A3</td><td>1B3</td><td>1C0</td><td>1D3</td><td> 11</td><td> 11</td><td> 00</td><td> 10</td>

<td> 23</td><td>1A3</td><td>1B3</td><td>1C0</td><td>1D3</td><td> 11</td><td> 11</td><td> 00</td><td> 11</td>

<td> 24</td><td>1A3</td><td>1B3</td><td>1C1</td><td>1D0</td><td> 11</td><td> 11</td><td> 01</td><td> 00</td>

<td> 25</td><td>1A3</td><td>1B3</td><td>1C1</td><td> 101</td><td> 11</td><td> 11</td><td> 01</td><td> 01</td>

<td> 26</td><td>1A3</td><td>1B3</td><td>1C1</td><td>1D2</td><td> 11</td><td> 11</td><td> 01</td><td> 10</td>

<td> 27</td><td>1A3</td><td>1B3</td><td>1C1</td><td>1D3</td><td> 11</td><td> 11</td><td> 01</td><td> 11</td>

<td> 28</td><td>1A3</td><td>1B3</td><td>1C2</td><td>1D0</td><td> 11</td><td> 11</td><td> 10</td><td> 00</td>

<td> 29</td><td>1A3</td><td>1B3</td><td>1C2</td><td>1D1</td><td> 11</td><td> 11</td><td> 10</td><td> 01</td>

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Correlation can be established as follows between Table 4, which indicates the exit code and the wiring system for the EBCDIC keyboard in Figure 4A, and the latter figure. Pressing the key 20, which puts the four switching elements A to D in contact with the elastic diaphragm 51B, causes the appearance of a positive logic signal at the output pins 1A3, 1B3, 1CQ and 1D0. This gives exit code 11110000. Key 20 is connected to these output pins by wiring on both sides of the wiring panel, as shown in Figure 4A, where the switching elements and wiring on the same side of the panel as these switching elements are shown in solid lines, the dots indicating the connection holes between these conductors and the switching elements, and the dotted lines the conductors located on the opposite side of the wiring panel. For example, the switching element B of the key 20 is connected by a solid line to the output pin IB3, the switching elements A and D are connected by wiring carried out on both sides of the wiring panel (shown by dotted lines and solid lines) to pins 1A3 and 1D0, and switching element C is connected by wiring on one side of the panel to output pin 1C0.

Although the actuation of a given key results directly in the generation of a 16-bit code at the output pins 1A0 to 1D3, this code is here decoded so that an 8-bit output code is obtained to pins 310, 320, 330, 340, 350, 360, 370 and 380 of Figure 4A. The same decoding logic that provides an 8-bit exit code is used for simultaneous key press detection and electrical contact verification as described below.

As shown in Table 4, bits 1 and 2 of the output code are determined by the state of the output pins 1A0, 1A1, 1A2, and 1A3. Bits 3 and 4 of the output code are determined by the state of the output pins

1B0 to 1B3. Bits 5 and 6 of the output code are determined by the state of the output pins 1C0 to 1C3, and bits 7 and 8 by the state of the output pins 1D0 to 1D3. For each set of pins A, B, C or D, the two associated bits of the exit code will be zeros if the zero pin (i.e. 1A0_, ABO, 1C0_, or 1D0_) is at one level positive logic. If pin 1 is at a positive logic level, the associated bits of the exit code will be 01. If pin 2 is at a positive logic level, the associated bits of the exit code will be 10. Finally, if pin 3 is at a positive logic level, the associated bits of the exit code will be 11. Thus, the pins 1A0 to 1A3 of the wiring panel control the state of the output pins 310 and 320 representing bits 1 and 2 respectively.

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Bits 1 and 2 will be 00 if pin 1A0 is at a positive logic level, if pin 1A1 is at a positive logic level, 10 if pin 1A2 is at a positive logic level, and 11 if pin 1A3 is at a positive logic level.

Like Figure 3, Figure 4A shows only 10 of the keys on a much larger keyboard, but shows the logic of the entire keyboard.

How the signals at output pins 1A0 through 1D3 are decoded to provide simultaneous key press detection and electrical contact verification logic, as well as the 8-bit EBCDIC code, is described below at using Figure 4A. The data selector / multiplexer (DS / M) 211 of Figure 4A is shown in more detail in Figure 4B and will be described later. It suffices for the moment to say that the outputs of any DS / M will be negative if, and only if, one of its four inputs is positive. COI inverters OR circuits have a positive output when one or other of their inputs, but not both, is positive. An inverter circuit (I) reverses the signal received at the input. An AND inverter circuit (AI) has a negative output when all of its inputs are positive. A monostable circuit (SS) gives a positive output whenever its input becomes positive. A negative inverter OR circuit t-ΟΙί gives a negative output B if one of its inputs, but not both, is negative. A parity generator (PG) circuit gives a positive output B when an even number of its inputs is positive, and a negative output when an odd number of its inputs is positive.

Output pin 1A0 is connected to DS / M 211. Pin 1A1 is connected to DS / M 211 and circuit 01. 272. Pin 1A2 is connected to DS / M 211 and circuit 01 271. Pin 1A3 sst connected to DS / M 211 and circuits 01 271 and 272. Pin 1B0 is connected to DS / M 212.

Pin 1B1 is connected to DS / M 212 and to circuit 01 274. Pin 1B2 is connected to DS / M 212 and to circuit 01 273. Pin 1B3 is connected to DS / M 212 and to circuits DI 273 and 274. Pin 1C0 is connected to DS / M 213. Pin 1C1 is connected to DS / M 213 and circuit 01 276.

Pin 1C2 is connected to DS / M 213 and circuit 01 275. Pin 1C3 is connected to DS / M 213 and circuits 01 275 and 276. Pin 1B0 is connected to DS / M 214. Pin 1D1 is connected to DS / M 214 and to circuit 01 278. Pin 1D2 is connected to DS / M 214 and to circuit 01 277. Pin 1D3 is connected to DS / M 214 and to circuits DI 277 and 278.

All pins 1A0 to 1D3 are connected to a positive voltage source.

The output of the DS / M 211 is inverted by the inverter 215 and transmitted to the AI ​​219 circuit. The output of the DS / M 2'2 qst inverted by the inverter 216

23162 and transmitted to the AI ​​219 circuit. The output of DS / M 213 is inverted by the inverter 217 and transmitted to the AI ​​219 circuit. The output of the DS / M 214 is inverted by the inverter 210 and transmitted to the AI ​​219 circuit. negative output from any DS / M is therefore inverted and appears as ⁵ of a positive input of the AI ​​219 circuit. The output of the AI ​​219 circuit will therefore be positive when one, and only one, of pins A, one and only one of pins B, one and only one of pins C, and one, and only one, of pins D, will be at a positive logic level. The output of the AI ​​219 circuit is transmitted to the monostable circuit¹⁰ 220, the output of which appears on line 210 for detecting simultaneous pressing of keys, which line is at a positive logic level when one, and only one, of keys 20 to 29 is in contact with the elastic diaphragm 51B.

The output of the monostable circuit 220 is also transmitted to the circuits

AI 301 to 308. The output of circuit 01 271 is transmitted to circuit AI 301, that of circuit 01 272 to circuit AI 302, that of circuit 01 273 to circuit AI 303, that of circuit 01 274 to circuit AI 304, that of circuit 01 275 to circuit AI 305, that of circuit 01 276 to circuit AI 306, that of circuit 01 277 to circuit AI 307, and that of circuit 01 270 to circuit AI 300.

The circuits 301 to 300 therefore have a positive output when a key, and only one key, has been actuated as indicated by the signal on line 210 and the corresponding bits 1 to 8 have been decoded from the output pins A10 to 1D3 via circuits 01 271 to 278. The outputs of the AI ​​circuits 301 to 308 are maintained in the flip-flops of corresponding bits, composed of a circuit -01 and an AI circuit, until these flip-flops are restored by the appearance of a signal at pin 300. Likewise, the signal for detecting simultaneous pressing of keys is maintained in the flip-flop bit, constituted by circuits 01 230 and AI 260, so as to maintain the signal at output pin 390 ³⁰ at a logic level indicating a verification of good electrical contact and inviting the logic using the device (not shown) to accept the exit code appearing at pins 310 to 380.

The output of the monostable circuit 220 is therefore transmitted to the circuit 01 230, then to the circuit AI 250 and to the output pin 390. The output of the ³⁵ circuit AI 301 is transmitted to circuit -01 311, then to circuit AI 321 and to the output pin 310 of bit 1. The output of circuit AI 302 is transmitted to circuit -01 312, then to circuit AI 322 and to pin output 320 bit 2. The output of the AI ​​circuit 303 is transmitted to the circuit -01 313 then to the AI ​​circuit 323 and to the output pin 330 of bit 3. The output of the circuit

4 ° AI 304 is transmitted to circuit -01 314, then to circuit AI 324 and to

23162 output pin 340 of bit 4. The output of the AI ​​circuit 305 is transmitted to the circuit -01 315, then to the AI ​​circuit 325 and to the output pin 350 of bit 5. The output of the AI ​​circuit 306 is transmitted to the circuit -01 316, then to the AI ​​circuit 326 and to the output pin 360 of bit 6. The output of the AI ​​circuit 305 is transmitted to the circuit -01 317, then to the circuit AI 327 and to the output pin 370 of bit 7. The output of the AI ​​circuit 308 is transmitted to the circuit -01 318, then to the AI ​​circuit 328 and to the output pin 380 of bit 8. The outputs of the AI ​​circuits 321 to 328 are also transmitted to the PG circuit 329, the output of which appears at pin 331. The signal transmitted on the restoration line and appearing at pin 300 is transmitted to the AI ​​circuit 260 and to the AI ​​circuits 321 to 328. The output of the AI ​​circuit

260 is also retransmitted to circuit -01 230, that of circuit AI 321.

to circuit -01 311, that of circuit AI 322 to circuit -01 312, that of circuit AI 323 to circuit -01 313, that of circuit AI 324 to circuit 01 314, that of circuit AI 325 to circuit -01 315, that from circuit AI 326 to circuit -01 316, that of circuit AI 327 to circuit -01 317, and that of circuit AI 328 to circuit -01 318.

With the logic described above, the signals appearing at the output pins 1A0 to 1D3 representing the closing of contacts comprising the switching elements of a given key 20 to 29 and the elastic diaphragm 51 B, are decoded in the form of an 8-bit code on pins 310 to 380, and signals for verifying good electrical contact and for detection of simultaneous pressing of keys are generated on lines 210 and 390.

A more detailed description of DS / M 211 in Figure 4A is given below using Figure 4B. The other DS / ΙΊ, 212 to 214, are similarly connected and provide similar functions. As can be seen in Figure 4B, a negative signal appears on the output line

261 when one, and only one, of pins A10 to 1A3 is earthed due to the closing of the corresponding switch. These switches represent the switching elements A of the different keys 20 to 29.

Pin 1A0 is connected to the inverter 221, pin 1A1 to the inverter 222, pin 1A2 to the inverter 223 and pin 1A3 to the inverter 224.

The connections with the inverters 221 to 224 represent the four input lines which, in FIG. 4A, constitute the inputs of the DS / M 211 to 214.

Wiring positions E, E0 and E15 are not shown in Figure 4A. The wiring positions E7, E11, E13 and E14 are maintained at a positive voltage via the resistor R1. However, the wiring positions E, E0 to E6, E8 to E10, E12 and E15 are grounded.

Ground voltage appearing at wiring position E is reversed

23162 by the inverter 229 and transmitted to the circuits ET 231 to 246. This signal can be used to condition all the circuits ET 231 to 246. However, the ground voltage at the wiring position EO is transmitted to the circuit ET 231, which blocks this last. Similarly, and for the same function, the ground voltage at point E is transmitted to the circuit ET 232, that of point E2 to the circuit

AND 233, that of point E3 to the circuit AND 234, that of point E4 to the circuit

AND 235, that of point E5 to the circuit AND 236, that of point E6 to the circuit

AND 237, that of point E8 to the circuit AND 239, that of point E9 to the circuit

AND 240, that of point E10 to the circuit AND 241, that of point E12 to the circuit

ET 243, and that of point E15 to circuit ET 246. Furthermore, the positive voltage at point E7 is transmitted to circuit ET 238, in order to condition the latter. Likewise, the positive voltage at point E 11 is transmitted to the AND circuit 242, that from point E13 to the AND circuit 244, and that from point E14 to the AND circuit 245.

The output of the inverter 221 is transmitted on line 252 to the circuits

ET 231, 233, 235, 237, 239, 241, 246, and 245. The output of the inverter 221 is also transmitted via the inverter 225 along the line 253 to the circuits ET 232, 234, 236, 236, 240, 242, 244 and 246.

The output of the inverter 222 is transmitted on line 254 to the circuits

ET 231, 232, 235, 236. 239, 240, 243 and 244. The output of the inverter 222 is also transmitted via the inverter 226 on line 255 to the circuits ET 233, 234, 237, 238 , 241, 242, 245 and 246.

The output of the inverter 223 is transmitted on the line 256 to the AND circuits 231 to 234 and 239 to 242. The output of the inverter 223 is also transmitted on the line 257 via the inverter 227 to the AND circuits 235 to 238 and 243 to 246. The output of the inverter 224 is transmitted on the line 258 to the circuits ET 231 to 238. The output of the inverter 224 is also transmitted on the line 259 via the inverter 22B to circuits ET 239 to 246. The outputs of circuits ET 231 to 246 are transmitted to the circuit

OR 250, the output of which appears at the output pin 261. In the case of the arrangement shown in FIG. 4B, a negative signal appears at the output pin 261 when one and only one of the inputs of the inverters 221 to 224 is positive.

Although the essential characteristics of the invention applied to a preferred embodiment of the invention have been described in the foregoing and shown in the drawings, it is obvious that a person skilled in the art can bring to it any modifications of form or detail which he judges useful, without departing from the scope of said invention.

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