SU813398A1 - Data input device - Google Patents

Description

(54) DEVICE FOR INPUT OF INFORMATION

one

The invention relates to computing and can be used in input devices for computers using a keyboard.

A device for inputting information is known, comprising a keyboard connected to a coding unit, generators, OR elements, a bounce block 1.

The disadvantage of this device is low reliability.

Closest to the present invention is a device comprising a keyboard, the outputs of which are connected to the inputs of the encoder, the outputs of which are connected to the inputs of the OR element and the information inputs of the register, the outputs of which are connected to the outputs of device 2.

The disadvantage of this device is its complexity and low reliability.

The purpose of the invention is to increase the reliability of the device.

The unallocated goal is achieved by the fact that a device containing a keyboard, the outputs of which are connected to the inputs of the encoder, the outputs of which are connected to the inputs of the OR element and informational

the inputs of the register whose outputs are connected to the outputs of the device, the delay element, the element NO, the AND element and the one-shot, the input of which is connected to the output of the OR element, and the output to the inputs of the delay elements and NOT, the inputs of the AND element connected to the outputs of the delay elements and NOT , and the output of the AND element is connected to the control input of the register.

FIG. 1 shows a diagram of the device; in fig. 2 - time diagram of his work.

The device contains the keyboard 1, the encoder 2, the element 3 OR, the one-shot 4, the register 5, the delay element 6, the element 7 NOT, the element 8 I. The position 9 denotes the outputs of the device.

The device works as follows.

In the initial state, when none of the keys of the keyboard 1 is pressed, the output level of the encoder 2 receives the zero level, the outputs of element 3 OR, the one-shot 4 and the delay element 6 are also zero. At the output of element 7, NOT is the logical level 1, at the output of element 8, And is the level of logical 0.

Register 5 is in the zero state.

When you press any key on the keyboard i on the output buses of the encoder 2, a parallel binary code appears, in the form of unit voltage levels on the corresponding output buses. Due to the bounce of the contacts of the keyboard switches, these levels have the form of a burst of pulses at the time of switching contacts (ti of Fig. 2a).

This signal is fed to the information inputs of the register 5 and through element 3 OR triggers a one-shot 4, which produces a pulse of the level of a logical unit. (Fig. 26), the duration of which is longer than the time of contact bounce, usually not exceeding 10-20 microseconds.

The pulse from the output of the one-shot 4 through the delay element 7 (tg-t in Fig. 2c) is fed to one input of the element 8 I, and through the element 7 NOT (tf-ta Fig. 2d) to the second input of the element 8 I.

At the output of the element 8 And there is a rising edge of the pulse of the one-shot

(Fig. 2d). Received at the output of element 8 And the pulse arrives at the control input of register 5 and allows the binary code entering from the output buses of the encoder 2 to the information inputs of register 5 to be written to the Register 5. The erroneous input of information to the register 5 at random pressing of the second key on the keyboard 1 is prevented the presence of a logic level 1 at the output of the element 3 OR, since the one-shot 4 does not start and no separation of the trailing edge of the pulse occurs.

When the previously pressed key is released, the zero voltage level appears on the output buses of the encoder 2, also accompanied by bursts of pulses due to contact bounce (tj in Fig. 2d)

The operation of the device proceeds as above: a one-shot 4 is started (is-t / in Fig. 26) and a pulse is generated to enter information into register 5 (in Fig. 2e). Register 5 is set to the zero state, since its information inputs currently have a voltage level of logical 0.

Thus, in spite of the bounce of the contacts of the keyboard 1 switches, the outputs of register 6 generate a binary code that exists during the entire time a key is pressed.

Claims (2)

Invention Formula A device for entering information containing a keyboard, the outputs of which are connected to the inputs of an encoder, and the outputs of which are connected to. the inputs of the OR element and information inputs of the register, the outputs of which are connected to the outputs of the device, characterized in that, in order to increase the reliability of the device, a delay element, an element NOT, The AND element and the one-shot whose input is connected to the output of the OR element, and the output to the inputs of the delay elements and NOT, the inputs of the AND element are connected to the outputs of the delay elements and NOT, and the output of the AND element is connected to the control input of the register. Sources of information taken into account in the examination 1. USSR USSR Certificate of Authenticity No. 398941, cl. G 06 F 3/02, 1974. 2. USSR author's certificate No. 531146, cl. G 06 F 3/02, 1977 (prototype). but five yo