SU752802A1 - Touchless keyboard - Google Patents

Description

(54) TOUCH KEYBOARD

one

The invention relates to switching technology.

Known touch keypads containing a multiplexer, infoO1 4aational inputs of which are connected to 5 touch pads, as well as netchik and shift register 1.

The disadvantage of this device is low reliability of operation,

The closest technical solution to the proposed one is the touch keyboard, which contains a multiplexer, the information inputs of which are connected to the touch pads, the control inputs - with the outputs of the 15 main counter, and the gate input is connected to the clock edge, as well as a shift register, the information inputs of which are connected by the outputs of the main tC4eT4liKa, and 20 outputs are connected to the information output buses 2.

A disadvantage of this device is low reliability of operation .25

The purpose of the invention is to increase the reliability of the touch keyboard;

. This goal is achieved due to the fact that in the touch keyboard containing the multiplexer, information

The inputs of which are connected to sensor pads, the control inputs are connected to the outputs of the main counter, and the gate input is connected to the clock bus, as well as the shift register, the information inputs of which are connected to the outputs of the main counter, and the outputs are connected to the information output buses ment OR NOT and an additional counter, the zeroing input of which is connected to the output of the first element. OR NOT, one of the inputs of which is connected to the clock bus, and the other input - to the multiplexer output and the counting input of the main counter, the counting input of the additional counter is connected to the output of the second element OR NOT, one of the inputs of which is connected to the output of the last bit of the main counter, and another input - to the output of the last digit of the additional counter, clocking the input of the shift register and the additional output bus.

The drawing shows a functional diagram of the sensor; keyboard.

The device contains a multiplexer 1, the information inputs of which are connected to the touch pads

2, the control inputs with the outputs of the main counter 3, and the gate input connected to the clock bus 4, the shift register 5, the information inputs of which are connected to the outputs of the main counter, 3, and the outputs with information output buses b, the additional counter 7, input zeroing which is connected to the output of the first element

OR NOT 8, one of the inputs of which is connected to the clocking bus 4, and the other input - to the output of the multiplexer 1

and the counting input of the main counter 3, the counting input of the additional counter 7 is connected to the output of the second element OR NOT 9, one of the inputs of which is connected to the output of the last discharge of the main counter 3, and the other input to the output of the last discharge of the additional counter 7 clocking The input of the shift register 5 and the additional output bus 10,

The operation of the touch keyboard is as follows. In the initial state, the operator does not touch the touch pads 2. At the first moment after turning on the power, the counter 7 is filled. The clock pulses pass to the output of multiplexer 1 and initiates the count of the counter 3. Sequential a change in the states at the outputs of the counter 3 connected to the control inputs of the multiplexer 1 leads to the sequential polling of the information inputs of the multiplexer 1 connected to the touch pads 2, since one of the the inputs of the element OR NOT 8 receive clock pulses of negative polarity, and its other input matches the pulses of positive polarity coinciding with them in time from the output of multiplexer 1, at the output of the element OR NOT HE 8, and therefore, at the input of zero resetting of the counter 7 a signal with a logic zero level is maintained; If, when the power is turned on, the output of counter 7 sets a signal with a logic zero level,

The counting input of counter 7 through the element OR-HE 9 is applied to the pulses from the output of counter 3 until the output of the counter 7 fails to install a signal with the level of a logical unit that prohibits further g to pulse through the element OR-HE 9 to the counting input of counter 7. Obviously, this will happen when the second counter 7 fills half of its capacity. If, however, when the power is turned on, the output of the counter 7 is immediately set to a signal with the level of a logical unit, then the pulses are not fed to the counting input of the counter 7 and the device is ready for operation.

When one of the touch pads 2 is touched, when the counter 3 is set to the state corresponding to the number of the pressed touch pad 2, no pulse of positive polarity is generated at the output of multiplexer 1. At the same time, counter 3 stops scanning the information inputs of multiplexer 1, remaining in the specified state. Signal with a logical zero level from the output

 multiplexer 1 permits the passage of clock pulses through the element OR NOT 8 to the zeroing input of the counter 7. At the output of the counter 7, a voltage drop from

5 logic level, units to the logic zero level, which records the code combination from counter 3 to the shift register 5. During the transient period, the pulses from the output of the OR-NOT 8 element generated at the moment of the contact of the operator’s finger with the touch pad 2 disappear on the counting input of counter 7, toggle it. But the pulses from the output of the element OR-NE 8, generated by the subsequent appearance of the contact, each time return the counter 7 to its original state, preventing it from filling up to half of its capacity.

Claims (2)

Claims. A touch keyboard containing a multiplexer, the information inputs of which are connected to the touch pads, the control inputs to the outputs of the main counter, and a strobe input connected to the clock bus, and the shift register, the information inputs of which are connected to the outputs of the main counter, and the outputs. with information output buses., characterized in that, in order to increase reliability, two OR-NOT elements and an additional account are introduced into it, a zero input which is connected to the output of the first OR-NOT element, one of which inputs is connected to a clock bus, and the other input - to the output of the multiplexer and. the counting input of the main counter, the counting input of the additional counter is connected to the output of the second element OR NOT, one of the inputs of which is connected to the output of the last digit of the main counter, and the other input to the output of the last discharge of the additional counter, the clock input of the shift register and the additional OUTPUT tire. Information sources. taken into account. ;, Electronics, M., Mir, 1975, No. 4, .c, 6.2,. , 2. USSR author's certificate No. 575773, cl. H 03 K 17 / 20,15,06.76 5 (prototype).