SU1157685A1 - Sensory keyboard - Google Patents

Abstract

1. A TOUCH KEYBOARD containing touch pads, a multiplexer whose address inputs are connected to the outputs of the counter and in-. a standard input of the register, and the output is connected to the register write enable input, as well as a generator, the output of which is connected to the counter input and gate inputs of the multiplexer and the register, which in order to increase reliability, the current distributors are entered into it, the input of each current distributor is connected to the corresponding sensor pad, the second input is connected to the corresponding information input of the multiplexer, and the outputs of the current distributors are connected to the common bus. 2. The keyboard according to claim 1,. O t l with the fact that each current distributor is made on a type transistor, the base and emitter of which are the first and second inputs, respectively, and (L collector, the output of the current distributor. Cf O) 00 ate

Description

eleven

The invention relates to a pulse technique - and can be used in control panels and in input devices and information output.

Known touch switches containing sound pads, elements 2I-NOT, D-triggers, inverter, generator. In this device, each touch pad requires the inclusion of an individual element 2I-NOT and a D-flip-flop in the circuit, which greatly complicates the design and degrades the reliability of L1} The closest to the technical essence of the invention is a touch keyboard containing touch pads, multiplexer The information inputs of which are connected to the touch pads, the address inputs are connected to the meter inputs, and the gate input is connected to the generator output, the clock input of the counter and the gate input the register house whose information inputs are connected to the counter outputs, and the register outputs are the output of the touch keyboard 2.

In devices of this type, the operator’s touch on the touch pad leads to the appearance of an additional delay in switching the multiplexer by the time required for charging the capacity introduced by the operator into the system (the capacity of the operator’s body relative to the common bus). This additional delay in the total switching delay of the multiplexer is commensurate with its own switching delay, and the ratio of these values determines the reliability and sensitivity of the device.

However, the amount of capacitance introduced by the operator is insufficient for the ratio to reach at least 10, as a result of which the reliability and sensitivity of the keyboard are insufficient to provide the necessary reliability of the signals at its output.

The purpose of the invention is to increase the reliability of operation by increasing the additional delay of switching the multiplexer during the transition process at its information inputs.

576852

The goal is achieved by the fact that a touch keyboard containing touch pads, a multiplexer, the address inputs of which connect 5 to the counter outputs and information inputs of the register, and the output are connected to the register recording enable input, as well as a generator whose output is connected to the counter input and gates the multiplexer and register inputs, current distributors are introduced, the first input of each current distributor is connected to the corresponding touch pad, tS the second input is connected to the corresponding information board at the multiplexer input, and the outputs of the current distributors are connected to a common bus.

0 In addition, each current distributor is made of a pp-type transistor, the base and emitter of which are the first and second inputs, respectively, and the collector is the output of the current distributor.

The drawing shows a functional diagram of the device. I

The device contains touch

platforms 1, each of which is connected to the corresponding information input of multiplexer 3 through the current distributor 2, whose address inputs are connected to counter 4, and register 5. Generator

5 6 with its output is connected to the clock input of the counter 4 and the gate inputs of the multiplexer 3 and register 5, and the output of the multiplexer 3 is connected to the resolution enable input of the register 5,

0 the outputs of which are the outputs of the device.

. The device works as follows.

In the initial state, all touch pads 1 are free. The pulses from the output of the generator 6, entering the input of the counter 4, change the potentials at its outputs and at the address inputs of the multiplexer 3. When Lenin receives a pulse from the output of the generator 6. the gate input of the multiplexer 3 opens, and an output signal appears at its output entering the permission input

5 registers.

From the information input of multiplexer 3, whose number corresponds to the combination of sig31 levels

at its address inputs, a current begins to flow, which flows into the current distributor 2. Depending on the distribution coefficient, this current is distributed in such a way that a significant part of it goes to the common bus, and the remainder goes to the touchpad bus to charge the installation capacitance and the capacitance introduced by the operator before the voltage threshold of the NS level of the multiplexer 3. Since the current is the charge of the indicated capacitances is slightly less than the current drawn from multiplexer 3, the duration of the transient process at its information input will increase by about the same time, i.e. the duration of the additional multiplexer switching delay will increase by about the same time, which will increase the reliability of the touch keyboard.

When the voltage at the information input of the multiplexer 3 reaches the threshold value, the latter switches and the enable signal is removed from its output. And from the register enable input 5, therefore at the moment the pulse ends at the generator output 6 and the gate input register. 5 does not write information to register 5 .

 The end of the pulse at the output of the generator 6 causes the multiplexer 3 to turn off, all its information inputs are closed, the state of the counter 4 is changed, preparing a survey of the next touch pad. Capacity of installation, brought operato76854

rum discharged through leakage resistance.

With the arrival of the next pulse from the output of the generator 6, the cycle 5 is repeated.

The current distributor 2 in the proposed touch keyboard is implemented on a p-type transistor, the base of which is connected to the touch pad bus, the emitter is connected to the multiplexer information input, and the collector is connected to the common bus. In this case, the transistor operates in the active mode during the entire transition mode at the information inputs of the multiplexer.

When the transistor current gain is equal to B, the current supplied to its emitter from the multiplexer information input is distributed so that its base

one

part of the current

branch only

B-t-1

emitter, and on its collector - the rest of the emitter current. At the same time, the voltage at the emitter of the trazistor repeats the voltage at its base.

Thus, by performing a current distributor on a transistor with a current gain equal to B, it is possible to reduce the current applied by the operator capacitor by a factor of approximately раз and, accordingly, the additional switching time of the multiplexer during a transient at its information Inputs, thanks to which a positive effect is achieved.

Claims (2)

1. A TOUCH KEYBOARD containing sensor pads, a multiplexer whose address inputs are connected to the counter outputs and register information inputs, and the output is connected to a register write enable input, and a generator whose output is connected to the counter input and the gate inputs of the multiplexer and register, characterized in that, in order to increase reliability, current distributors are introduced into it, while the first input of each current distributor is connected to the corresponding touch pad, the second key entry to the corresponding favoring information multiplexer input, and outputs a current distributor connected to the common bus. 2. The keyboard according to claim 1, wherein each current distributor is made on a p ~ p-p ^ -type transistor, the base and emitter of which are the first and second inputs, respectively, and the collector is the output of the current distributor. ί SU .... 1157685