DE1906720A1 - Electronic alphanumeric keyboard - Google Patents

Description

The invention relates to an electronic alphanumeric keyboard for entering data in data printing, transmission or processing systems, with encrypted output signals in simultaneous operation on a number of lines and with an encryption obtained with the aid of ferromagnetic cores. In particular, the invention relates to an alphanumeric keyboard of the type which
contains a system of work keys with mechanical actuation by hand and these individually assigned bistable magnetic cores, which are saturated from input wire connections positively or negatively and which simultaneously on a number of output wire connections a combination of binary signals against the character of the corresponding work key in
a given encryption.

An electronic alphanumeric keyboard with an encrypted output must essentially meet two requirements χ

a) All keys must work independently of each other, i.e. if one or more keys are pressed, miss it will also be possible to write other characters ^

b) the risk of overlapping two characters due to the Simultaneous pressing of the corresponding buttons must be reduced to the minimum in order to be able to exit on the Godier lines mixing or superimposing to avoid two encodings corresponding to the simultaneously given characters.

In the case of the known keyboards, this disadvantage is avoided by that a blocking or regeneration device is inserted, which from an economic point of view in each lall is very annoying.

According to the present invention, any locking or Generation devices are omitted because the encryption signals have a duration that is much shorter than the time of the shift that occurs with the so-called simultaneous attack of two keys.

It is necessary to make a number of considerations regarding the simultaneity of two key presses.

As a result of careful statistical study, it has been noted that the probability of occurrence a simultaneity in the pressing of any two keys is almost zero, insofar as two keys appear to be simultaneously are pressed, always two time-shifted and separated by a short period of time T result. The aim of the statistical investigation was to

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The most likely value of the shift time T should be used when two keys are pressed. In fact, it is possible _{to assign a probability P T} to each shift time, which can be interpreted as the relative frequency with which a given shift time T occurs.

are therefore for given operating personnel or operators Curve representations have been drawn for which the times of the displacement T measured with an oscilloscope as the abscissa and the relative frequency as the ordinate P ^ ,, with which a given shift time T occurs, are applied.

A bell-shaped or Gaussian curve of the equation became for all operators

exp

obtained in which I a proportionality factor and ο the mean mean spread. The most likely shift time for all operators is approximately 10 ms. It it can be concluded from this that if the duration of the encryption signal is less than 10 milliseconds, the The dangers of superimposing the output signals are extremely small. By choosing a time of about a microsecond as the the duration of the output signal on the encryption lines minimizes the risk of interference reduced or almost eliminated and any need for locking and regeneration devices in the keyboard avoided. For this purpose, a magnetic core is assigned to each work key, in addition to the feed lines and input lines nor the output lines that represent the corresponding characters in a given code Delivering signals, guiding.

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The object of the invention is to provide a device create, which make it possible when the work buttons are pressed!;, the sudden change in the saturation of the magnetic cores in such a way as to cause the times of mechanical handling of the change sufficiently small compared to the most probable shift time of the impact and beyond an order of magnitude close to that of an electronic switchover the kernels are

Indeed, the use of mechanical changeover switches requires more known ones Type, e.g. micro switch, times for actuation and reset that are far too long for the combined movement of a number of mechanical components so that the speed of the generated electrical signals from a relative slowness of the mechanically operating part is accompanied. Therefore, under these conditions, that of The input speed allowed by the keyboard is jeopardized by its mechanical properties.

With the invention, these disadvantages are avoided and the proposed Task solved by a keyboard, which consists of an electronic alphanumeric keyboard with a sentence by hand There are operable buttons, each of which is seated directly on a metal switch tongue, the ohmic contacts with two contacts in the rest or working position of the button and thereby supply wires differently to a voltage source lays, the feed wires with a bistable magnetic core assigned to the key in such an arrangement are coupled in such a way that the core is different in its two Directions is saturated in the said rest or working position and in the output wires coupled to the core induces a combination of pulses representing the pressed key in a given code.

Embodiments of the invention will now be described in more detail with reference to the drawing.
Show in it:

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Fig. Λ a curve which represents the probability of the Yerschie "practice time" when you hit two consecutive keys,

ig. 2 the temporal course of the input and output voltages for the magnetic cores used according to the present invention,

3 shows the working principle of a keyboard according to the invention,

Fig. 4 * the hysteresis curve of one used in the keyboard Magnetic core,

5 shows a "special embodiment for the circuit to switch the supply voltage of the magnetic cores used in the keyboard,

Fig. 6 different forms of Velligkeitsformen with the keyboard generated output signals and

7 shows a design of a keyboard according to the invention.

A fixed negative potential in the rest position of each key to an input connection in the coding assigned to the key Core applied When the button is pressed, the contact is interrupted with the negative voltage source and another contact is made with a positive voltage source, so that at the moment of contact with the positive source there is a change in saturation and as an output the encrypted signal at the Godier connections simultaneously with a predetermined duration, "for example of 900 nanoseconds, which only depends on the time necessary to reverse the flow in a nucleus is obtained.

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Once the bias of the core has been reversed, a signal will even appear on the output terminals then no longer be when the operator continues, holding down the key, and the aforementioned Godier outputs are therefore free to receive a new character code and so on, Juf that way is independence the operation of the buttons ensured · It is clear that when a button is in its rest position with a change from the positive source to the negative source of supply for returns the input terminal to the core, a signal of opposite sign will be present at the outputs which will conventionally be ignored or eliminated.

Fig. 2 shows the course of the change in the supply voltage over time Vi at the input connection to the magnetic core and the voltage Vu, which is used as the output at the Oodier connections occurs. The period of time marked tpn represents the time to change from the connection with the positive source to the Connection to the negative source (and vice versa) represent necessary time, which is a mechanical time, necessary for the Changeover switch from the interruption of the ohmic contact with the positive pole is brought to the ohmic contact turn on with the negative pole; for a good functioning of the keyboard with regard to the mechanical switching speed the time must be less than 200 microseconds be.

As for the possibility of returning a key to the rest position in accordance with the movement of another key into the working position with consequent deletion of the signals on one or more Oodier connections, as this is done by the Returning one key to the rest position would clear the input signal generated by the other key which has the opposite sign, it can be assumed that the same considerations as

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they have been discussed with regard to the simultaneity of pressing two keys.

For the purpose of obtaining a good mechanical efficiency of the keyboard as required, the connection between the input terminals of the cores and the positive or negative source is ensured by simple ohmic contacts actuated directly by the key. With reference to S ¹ Ig. 3, in which a schematic representation of the contacts a ¹ and b ^{1 of} the key 1 and the switching tongue 2 is shown, it should be emphasized that in the rest position a stool a is present at one end 5 of the tongue 2, which is attached to the other end 4 is, is constantly sitting on the negative contact a ^f. When the button is pressed, the tongue 2 comes to sit on the fulcrum f. This causes the tongue to bend so that the stool a is separated from the negative contact and another stool present at the end 3 of the tongue 2 b is brought into contact with the positive pole b ¹ . One of the advantages of this device is that not only do the stools a and b ^{touch the relevant contact surfaces a 1} and b ¹ , but thanks to the bending effect of the tongue 2, they are forced to slide on them, with better contact and better operation be ensured. In addition, the tongue 2 serves as a spring for the key. In order to reliably achieve these results, it must be ensured that the lever point f has a small distance from the tongue when the button is in the rest position.

It can also be observed how the operator feels is made possible to press a button resiliently, which is pressed into the out-of-contact position or into the rest position is without any danger of causing a signal in the output channel because the core is able to generate a new signal feed only if the button is in the opposite position

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sets to where it is when the operator is bouncy presses on this.

It is known that sliding contacts often voltage drops or reductions, at times down to zero, during the establishment of the contact itself. In the present case, these voltage drops have no effect, because, once the core has reversed its saturation, it will remain in the reversed state as long as the input terminal does not come back into contact with the opposite source Sign is brought. The circuit diagram of Fig. 3 shows the mode of operation for a button, it goes without saying that that a circuit identical to that of FIG. 3 is provided for each key, each with its code ' corresponds to the character represented by the key operating in this regard.

To simplify the drawing, a bistable magnetic core 5 is shown schematically by a thick straight line. A winding around the core is shown by a short line sloping to the left, when the winding is in a straight line designated sense is connected and by a short line sloping to the right - if the winding is in reverse Sense runs.

The magnetic core 5 with a rectangular hysteresis loop (Fig. 4-) is provided with a winding with an input terminal I, which is wound by a single and direct sense Turn is formed with a winding with an input terminal N, made by a single and reversed Sense wound turn is formed, and with the outgoing or output coding wires G1 to 07, which are in direct Sense. For example, seven can be encrypted

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Outputs for the lower case letters and seven for the large letters can be provided by means of a shift key can be selected so that the operator can use small and capital letters as required. can write.

The connection wires I and N are made of chrome-nickel.

The connection H is the bias wire of the core and is connected between the positive pole of the source E and earth, and the wires 01 to C7 are the coding connections lying between earth and the relevant outputs UI to U7.

Each core 5 therefore has a directly magnetically excited field as a result of the current flowing through the bias wire K. This excitation field is considered negative. When the key * is in the position shown in Fig. 3 , each core is also subject to a negative field thanks to that flowing through the input wire I connected between the negative pole of the source E 'via the tongue 2 and the contact a ¹ Exposed to electricity.

4 shows the hysteresis curve of a core. When the (key is in the position of Fig. 3 , the core is negatively saturated and its state is represented by point 6 in Fig. 4. Assuming that the key is pressed then the sign of the voltage is reversed and now a positive current flows through the wire I. It is well known that a counter electromotive force equal to the applied voltage E occurs in the input wire I and the current that is built up will be such that these conditions are met.

For each nucleus, this counter electromotive force is equal to df / dt, where f is the flux and t is time. Immediately after-

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which the voltage has changed from negative to positive, shifts the operating point on the hysteresis loop changes from 6 to 7 and at the same time the saturation of the core becomes vice versa, so that there is a change to point 8 on the hysteresis loop and the time required for the reversal T depends on the total variation 2F of the flux.

In the ideal case where df / dt »is constant, it follows that T = 2F / E, where T represents the duration of the pulse that is on the coding connections occurs at outputs U1 to U7 and sent to the feeders.

For the practical use of the keyboard, it is possible to make further simplifications compared to the coding cores described above for the best case. In fact, the two supply sources E and E ¹ shown in FIG. 5 can be reduced to a single source with a single sign, for example + E. It can be seen directly from FIG. 5 that when the tongue 2 shown schematically in FIG. The wire L should have a tap point F, which leads to earth, and its ends should be connected to two contact points A and B.

It is assumed that the switching element or switch 2 at B, as indicated in FIG. 5, is closed. The current ig will then flow in the direction indicated by the arrow, the relevant excitation field H _{B w ± rd} ^ _the ^ _{r ± g # 5} ^ ₆ , given Veise oriented and the core will be saturated, for example negative at point 6 in Fig. 4. If the connection is brought from B to A, then the current becomes i ^ in.

which flow opposite to the previous opposite direction, as indicated by the arrow, and thus the excitation field H _A also becomes the opposite direction to the

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earlier and the same absolute value. The core will consequently at the point; 8 of Fig. 4- will be positively saturated. When changing from negative saturation (point 6 of Fig. 4-) to positive saturation (point 8 of FIG. 4) the reversal signal occurs of the core at the output of the coding connections. The effect of this new arrangement compared to the previously described optimal execution manifests itself in a change in the shape and amplitude of the switching signal, as Fig. 6 shows.

In the optimal case of FIG. 3, the switching signal has the Shape and the amplitude of the curve Q in Fig. 6, while in the practical arrangement of Fig. 5, the switching signal has the course of curve E.

As a result, in the practical arrangement there is a reduction of 10% in the amplitude of the voltage of the Switching signal compared to the optimal execution, i. a signal R is obtained which is determined by the effect of the lack of an initial bias which forms the hysteresis curve (as in the arrangement according to FIG. 3) builds up, is disturbed. Fig. 4 explains the hysteresis curve, appropriately refers to the arrangement of FIG. 3.

It is necessary to note that in terms of Great versatility of the keyboard changed the encryption very much and other lines (e.g. an eighth line at the time), which may be necessary for the operation of storage devices for a number of characters could be, to the seven lines for the lower scripture characters and the seven lines for the upper letter box characters can be added.

A design of the keyboard according to the invention is shown in FIG. 7 shown.

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A single chrome nickel wire I with a diameter of 0.3 mm is wrapped around a core x 5 as shown in Fig. 7 to effect the switching of the core. In the rest position of button 1, tongue 2 closes the circuit through stool a via xLen contact A, so that the nucleus becomes negatively saturated. When the button is pressed in the working position, contact A is opened and the contact B closed over the stool b of the tongue 2, as a result of which the current in the opposite direction flows to the former and the core 5 with the over- ^ output switches to positive saturation.

A magnetic amplification of the switching signals is effected at the outputs of the coding channels C1, 02, 03 ... As Fig. 7 shows, each line is 0 with P primary of a transformer made up of about a hundred turns of a wire with a diameter of 0.2 mm consists of a rod made of Ferroxcube Type 3B with a Diameter of 1.6 mm is wound, while the secondary side S consists of about a thousand turns of a wire with a diameter of 0.2 mm, so that the switching signal at the output U is amplified ten times. Parallel to the output U of the secondary side S, a capacitor ″ C with 1000 pF and a diode D are arranged, which function have to eliminate disturbances and signals of a given sign to suppress the negative signals, for example.

It should be noted that the use of a single chromium-nickel wire enables a distributed load resistance aimed at for the voltage source for feed purposes.

As to the arrangement of the keys, as shown in FIG "7 is a plastic plate is provided with through seats 10 9, in which the keys are inserted in a simple manner, wherein the _t keys consist of one piece, consisting of plastics and

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are made parallelepiped or cylindrical shape and have a flange 11 on their underside, which the keys prevents it from being detached from the keyboard after it. once inserted into the plate 9 from below «each key is also extended and sits directly on a punch 12 on the switching tongue 2, which is made of beryllium bronze with a thickness of about 0.2 mm.

It should be noted that in the rest position the punch 12 of the key bends the tongue 2 slightly so that the lip 11 always held against the upper plate 9 and the contact A closed over the hump a of the tongue 2, which rests on it is.

When button 1 is pressed, tongue 2 flexes and moves downward until it touches fulcrum f, which is 0.5 mm from the tongue when the key is in the rest position. From the moment when the tongue touches the lever point f and only from this moment on does the contact A open and the button bends the tongue further and the bump b of the tongue when the button is pressed further at the end 3 continues to go up until it closes contact B.

It can be seen that in the depressed position the button can work elastically on the spot without making contact B is absent) equally, it can work elastically on the spot in the rest position without contact A being absent is.

It also allows the tongue 2 when the effect manually pressing button 1 stops the button itself from being returned to the rest position.

The tongue 2 therefore performs a number of modes of operation, i.e. the contacting, the springing and the return of the button aua

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The contacts A and B can be used as plan parts of a pressed circuit by means of a suitable metallization of the plates 9 and 13 schematically showing Mg. 7 can be obtained. For geometric reasons, the contact B lies on a projection 14 of the plate 91, the projection at the same time how the plate 9 ″ is shaped during casting.

The switching tongue 2 may form part of a single metal plate 15 which is cut out to include a central part from which as many arms or branches extend as the number of tongues is 2. The middle part of the plate 15 can be riveted to a projection 16 of the lower plate 13. The metal plate 15 will then be connected to one pole (eg the positive pole) of the voltage source, while the other pole is grounded.

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Claims (10)

190672Q claims 1. Electronic alphanumeric keyboard, characterized in that a number of manually operable keys (1) is provided, each of which is seated directly on a metallic switching tongue (2), the ohmic contacts (a ¹ , b ¹ ) with two contacts (A, B) produces in the rest or working position of the key and thereby places supply wires (I, N) differently to a voltage source (E), the supply wires being coupled to a bistable magnetic core (5) assigned to the key in an arrangement such that the core (5) is saturated in its two different directions in said rest or working position and in output wires (01, 02, ...) coupled to the core, a combination of characters representing the printed key in a given encryption induced. 2. Keyboard according to claim 1, characterized in that each tongue (2) is designed to be elastically movable and attached to a fixed one Support (13) is anchored at one end (4-), while the other end (3) can be moved by the corresponding button (1) is. 3. Keyboard according to claim 2 or 3j, characterized in that a number of tongues (2) formed from a single metal plate (15) are provided, the plate (15) is cut out to include a main body and tongue-forming arms extending therefrom. S09838 / U19 4. Keyboard according to claim 2 or 3 »characterized in that at the other end (3) of each tongue (2), which normally produces one of the two contacts (a ¹ , b!) Under the action of its own suspension, a lever point ( f) is arranged at an intermediate point along the tongue and the button (1) rests on the tongue on the side opposite the lever point and between the lever point and said one end in an arrangement such that when the button is operated it bends the tongue to move the other end out of contact with one end and into contact with the other of the two contacts. 5. Keyboard according to claim 4, characterized in that the other end (3) of each tongue (2) is bent to form two humps (a, b) which make sliding contact with the two contacts (a ¹ , b ¹ ) manufacture one after the other. 6. Keyboard according to one of claims 2 to 5, characterized in that the two contacts (a ¹ , b ¹ ) are flat parts (A, B) of a printed circuit (Fig. 7). 7. Keyboard according to one of claims 2 to 6, characterized in that that each tongue (2) is designed to be resilient in such a way that the corresponding key is returned to its rest position when the button is triggered manually. 8. Keyboard according to one of claims 1 to 7 »characterized in that that in comparison to each core (5) a single voltage source (E) is provided, one of which is also a terminal the corresponding tongue (2) and the other terminal thereof connected to one end of each of the feeder wires which Wrap around the core in opposite directions and its other end with the corresponding two contacts (Aj B) are connected one after the other. ■ 909838/1419 9- keyboard according to claim 8, characterized in that the two feed wires (I, N) have the shape of a single Have wire (L) with a tapping point (3?) Connected to the other terminal and a distributed Form load resistance for the voltage source. 10. Keyboard according to one of claims 1 to 9 »characterized in that that each output wire (01, 02, ...) with a step-up transformer, each one at its outputs capacitor (0) connected in parallel and a diode (D) to absorb interference signals and to suppress them of pulses having a "sign" is connected. ο keyboard according to one of claims 1 to 10, characterized by that the keys (1) are one-piece bodies with a parallelepiped or cylindrical shape, and inserted from below through openings (10) in a plate (9) and provided with flanges (11) which if the button is not pressed, rest against the underside of the plate and that each button (2) one down has protruding punch (12) which sits directly on the corresponding tongue. Bä / FÜ - 20 817 909838/1419