UA75415C2 - Device for protecting contacts against contact bounce - Google Patents

Abstract

The proposed device for protecting contacts against contact bounce contains a D trigger and interlock pulse forming unit. The input of the trigger is used as the input, and the output of the trigger is used as the output of the proposed device. The input of the interlock pulse forming unit is connected to the output of the trigger, and the output is connected to the timing input of the trigger. The interlock pulse forming unit contains a circuit for generating short pulses when the trigger switches from one state to the other and a circuit for starting the unit. The input of the interlock pulse forming unit is connected to the output of the trigger. The input of the starting unit is connected to the timing input of the trigger. The interlock pulse forming unit may contain an OR logic element and a switch. The proposed device is distinctive by its enhanced reliability and improved performance.

Description

Description of the invention

The invention belongs to automation and computer technology and is intended for the conversion of pulses, the edges of which are distorted by crushing due to the noise of electromechanical contacts, into single logical pulses normalized in terms of level and shape.

There are known devices for protection against chatter of a pair of switch contacts, which convert a chattering pulse into a single rectangular pulse free from chatter, the beginning and end of which, depending on the requirements, are either arbitrarily placed relative to the primary pulse, or coincide with the start of chatter, respectively 70 forward and reverse switching, which is required in some cases in automation systems, where accurate information about the moment of the start of closing and opening of contacts is required. These devices create a pulse that is as close as possible in shape and duration to the ideal pulse that would be generated by an ideal contact pair without chatter.

Known, for example, is a contact protection device (1) containing a delay circuit, preferably 19 single-vibrator, which forms a pulse blocking pulse that blocks the duration of the input pulse affected by the pulse, and an O-trigger, the information and reset inputs of which are connected to input of the device, and the clock input is connected to the output of the delay circuit, and the outputs of the U-flip-flop are the outputs of the device.

The features that coincide with the essential features of the claimed device are the delay circuit implemented in the claimed device in the form of a trigger circuit and an O-flip-flop, the information input of which is connected to the input of the device, and the clock input is connected to the trigger output circuits, and the outputs of the O-flip-flop are the outputs of the device.

The jingle in the output signal of a known device when a "1" pulse with a jingle at the edges is applied to its input is eliminated by delaying (blocking) for the time of the front jingle the recording in the U-trigger of the new state of the contacts (the level of the first positive jingle pulse at the beginning of switching from the level of "0 " to level "1"). c 29 Blocking is carried out by a delay circuit, namely, a single vibrator, which is triggered by the edge of the first positive G0) pulse of the positive ring. The jingle at the end of the input pulse "1" is eliminated by setting the trigger to "0" after the first pulse of the back jingle applied to the reset input of the trigger, and by blocking the recording of information for the time of the back jingle.

The disadvantage of this device is the delay of the beginning of the output pulse "1" relative to the beginning of the switching of the contacts on the switch, i.e. the error in reproducing the time position of the input pulse affected by the noise, which is "-- determined by the amount of the delay.

The closest in terms of technical essence to the invention is the discrete signal generator (2), which is selected for C prototype, which, like the claimed invention, contains a U-trigger with a static clock input, the information input of which is connected to the input of the device, and its the outputs are the outputs of the device, and the pulse shaper

From blocking, enabled between the flip-flop outputs and its clock input. -

In the prototype, the blocking pulse shaper consists of a timing node and a two-input AND-NOT logic element, and the timing node is made on a capacitor, each plate of which is connected: through a parallel-connected resistor and diode - to the output of the trigger and directly - to the input of the AND-NOT element , whose output is connected to the clock input of the trigger. With 50 The prototype device and the proposed device form a pulse whose beginning and end coincide with the beginning of the forward and reverse commutation cycle. After recording a new state in the trigger on the first pulse of the front and rear ring, the rectangular pulse generated by the blocking pulse generator prohibits rewriting for the entire duration of the ring.

However, in the prototype, as a result of connecting the covers of the capacitor of the timing unit to the inputs of the active AND-NOT logic element, the pulse at these inputs has long delays (one and more milliseconds) and has a very slow decay (back edge), while the pulse generated by the logic element at to the beat of 4! the inputs of the U-trigger must have a steep (duration of no more than 5 μs) front and fall, especially when the trigger is a microcircuit of the KMON series. This circumstance requires the use as a logical element of only t-special circuits, for example, a Schmitt trigger with a circuit I! at the input, intended for receiving gentle signals, and - 20 excludes the use of both passive, for example, diode-resistor circuits, unable to increase the steepness of the edges and declines of pulses, and ordinary active microcircuits of the KMON series due to their failure at gentle sl input signals. The second disadvantage of the prototype is that due to the single launch of the blocking pulse generator only at the beginning of the denkot pulse packet, the capacity of the capacitor must be calculated for the duration of the blocking pulse, which exceeds the duration of the denkot, which, with a significant duration of 29 denkot, requires a large capacity of the capacitor, proportional to this duration. and hinders miniaturization

GF) equipment.

In addition, since the prototype claims a time-setting unit with a capacitor, where the time-setting parameter is the capacity of the capacitor, which limits the miniaturization of the equipment, this excludes the use of other types of trigger-trigger circuits that are based on other physical phenomena, technical principles and circuit solutions , and contribute to miniaturization, for example, digital trigger circuits that use pulse counts to specify the time interval.

The invention is based on the task of improving the device for protecting against contact chatter through the appropriate execution of the blocking pulse shaper in order to increase the steepness of the pulses at the inputs and outputs of the device elements, thereby increasing the reliability of operation and expanding the class of pulse circuits and logic elements acceptable for use in the device , as well as provide the possibility of re-starting (the so-called "restart") of the blocking signal generator from each pulse in a packet of denkot pulses, which, when using trigger circuits with restart, provides a significant reduction in the capacity of the timing element (capacitor capacity, number of digits of counter circuits, etc. .), and, therefore, the dimensions of the equipment. This is explained by the fact that the trigger circuit with restarting can form an arbitrarily long pulse, depending only on the number of trigger pulses, provided that the duration of the nominal pulse of the trigger circuit, calculated for a single trigger, will be greater than the interval between trigger pulses.

The problem is solved by the fact that in the contact noise protection device, which contains an O-flip-flop with a static clock input, the information input of which is connected to the input of the device, and the outputs are the 7/0 outputs of the device, and a blocking pulse generator enabled between the outputs trigger and its clock input, according to the invention, the blocking pulse generator is made in the form of a serially connected generator of short pulses that correspond to the moments of the flip of the trigger, and a trigger circuit, and at least one input of the generator of short pulses is connected to the output of the trigger, and its output is connected to the trigger input of the trigger circuit, the output of which is connected to the clock input of the flip-flop.

The specified implementation of the blocking pulse generator provides sharp pulses at the inputs and outputs of the device nodes, which increases reliability and allows the use of a wide range of pulse and logic elements that meet specific requirements.

In addition, in the device of Fig. 3 between the generator of short pulses and the trigger circuit, an OR logic element is introduced, and the first input of the OR element is connected to the output of the element that performs the function of a switch, which is controlled by the signal of the trigger circuit, the information input of which is connected to input of the device, the second input of the OR element is connected to the output of the short pulse generator, and its output is connected to the trigger input of the trigger circuit.

In the device of Fig. 4, between the generator of short pulses and the trigger circuit, a switching element is introduced, which is controlled by the signal of the trigger circuit, the first information input of which is connected to the input of the device, and the second information input of this element is connected to the output of the generator of short pulses, and the output - with the start input of the trigger circuit.

Due to the introduced elements and connections according to paragraphs 2 and According to the claims of the invention, restarting of the blocking pulse generator is ensured with each denkot pulse, which, with a simple device scheme and a smaller capacity of the timing parameter of the trigger circuit, allows the equipment to be miniaturized. The essence of the proposed invention is explained by the drawings, which show: - in fig. 1 - scheme of the device according to Clause 1 of the formula; -- - in fig. 2 - time diagrams of voltages of this device; "g - in fig. C - scheme of the device according to Clause 2 of the formula; - in fig. 4- scheme of the device according to clause C of the formula; o - in fig. 5 - time diagrams of voltages of the device according to paragraphs 2 and From the formula. The proposed device (Fig. 1-1) contains an O-trigger 1 with a static clock input, the information input of which is connected to the input 2 of the device, and its direct and inverse outputs are, respectively, the direct and inverse 4 outputs of the device, and a pulse generator 5 blocking, which has a generator of 6 short pulses and a trigger circuit 7. The output of the generator of 6 short pulses is connected to the start input of the trigger circuit 7 loaded on the clock input of the trigger 1. At the same time, the input of the generator of 6 short pulses, depending on its specific circuit implementation, connected to one or with two outputs of trigger 1. The device (Fig. 3) additionally contains a logical element OR 8, the first input of which is . connected to the output of the element 9, which performs the function of a switch, which is controlled by the signal of the trigger circuit 7, and? the information input of which is connected to input 2 of the device, the second input of the OR element 8 is connected to the output of the short pulse generator 6, and its output is to the trigger input of the trigger circuit 7. The device (Fig. 4) additionally contains a switching element 10, which is controlled by the signal of the trigger circuit 7, the first information input -I of which is connected to input 2 of the device, the second information input is connected to the output of the generator 6 of short pulses, and the output is connected to the start input of the trigger circuit 7. o The device works as follows. "5" In the initial position, before the input 2 of the device receives a pulse affected by a detonator, there is a signal with a level of "1" at the output 5p of the trigger circuit 7, which allows the recording of the primary signal at the input 2 of the device, for example, a signal with a level of " 0", and a signal with the same level is formed at the output of the device. When the input 2 of the device is supplied with the pulse "1" affected by the noise at the beginning and at the end (Fig. 2, diagram a), the signal "1" corresponding to the first pulse of the sound is recorded in the trigger 1, and at the direct output Z of the device begins to form pulse "1" (Fig. 2, diagram B), after which, in response to a change in signal levels at the output of the trigger 1, the short pulse generator 6 generates a short pulse that triggers the trigger circuit 7 (Fig. 2, diagram c). As a result, a blocking pulse "0" is applied to the clock input of trigger 1, which prohibits writing

F) information (fig. 2, diagram 4). Since the duration of the blocking pulse should exceed the duration of the clock, the information recorded in trigger 1 is stored until the end of this pulse, despite the change in the signal at the input of the device. At the end of the blocking pulse, the state of trigger 1 and the signal at the output Z of the device does not change, since the fixed value "1" of the signal recorded earlier is present at the input of the device.

With the appearance at the input 2 of the device of a package of pulses of the rear dench, the trigger 1 goes to the "0" state, corresponding to the level of the first pulse of the rear dench, and the pulse "1" at the direct output of the device ends. The generator b of short pulses starts the trigger circuit 7, which prohibits the further recording of information in the trigger 1 and the change of the signal at the outputs of the device. At the end of the blocking pulse, permission is given 65 to record the established value "0" of the input signal, that is, the previously recorded information is confirmed - and the signal at the output Z does not change.

The operation of the device in Fig. 3 is similar to the one described above, with the difference that after starting the trigger circuit 7 with the pulse of the generator 6, short pulses through the element 9, opened by the pulse of the trigger circuit 7, to the second input of the OR element 8 and further to the input of the trigger circuit 7 start receive pulses of denkota, which restart the trigger circuit 7 (fig. 5, diagram e).

The device of Fig. 4 works similarly to the device of Fig. 3, but with the difference that after the start of the trigger circuit 7 by the generator b of short pulses, the switching element 10, during the existence of the blocking pulse, passes to the start input of the trigger circuit 7 pulses of noise from the input 2 of the device and disconnects the output of the shaper 6 from the start input of the trigger circuit 7 short pulses. 70 The proposed device can be implemented on standard integrated microcircuits used by industry. As a switch and a switch, it is possible to use standard microcircuits - switches or logic keys built on circuits 1, OR, etc. The shaper of short pulses can be differentiating CS-chains, the known scheme on the elements of EQUALITY or

INEQUALITY with an integrating CS chain or a delay of another type.

Sources of information: 1. US Patent No. 3925682, class 307/134, publ. 09.12.75. 2. A.S. USSR Mo 809523, MKY N 03 K 5/01, publ. 15.03.81.

Claims (2)

The formula of the invention 1. A device for protection against contact chatter, comprising a U-flip-flop with a static clock input, the information input of which is the input of the device and the outputs are the outputs of the device, and a blocking pulse shaper, the inputs of which are connected to the outputs of the flip-flop, and the output of which is connected to its clock input , which is characterized by the fact that the blocking pulse generator contains a series-connected short pulse generator and a trigger circuit, and at least one input of the short pulse generator is connected to at least one output (o) of the flip-flop, and the output of the trigger circuit is connected to the clock trigger input. 2. The device according to claim 1, which is characterized by the fact that an OR logic element is additionally introduced into the blocking pulse generator, the first input of which is connected to the output of the element that performs the function of a switch, the control input of which is connected to the output of the starting circuit, and the information input is connected to the input of the device, the second input of the OR element is connected to the output of the short pulse generator, and its output is connected to the start input of the starting circuit. "- C. The device according to claim 1, which differs in that a switching element is additionally introduced into the blocking pulse generator, the control input of which is connected to the output of the starting circuit, the first information input - to the input of the device, the second information input - to the output of the short-circuit generator pulses, and the output is the result of starting the starting circuit. - . and? - and 1 sh» - 70 sl ime) 60 b5