SU743181A1 - Device for preventing influence of two-contact switch-produced bounsing - Google Patents

Description

The invention relates to ektrodoavtomatika and can find application in control systems, regulation, control and computer technology.

Known devices designed to eliminate the effect of bounce from mechanical ^5- pin switches. The operation of such devices is based either on the integration of bounce signals before applying them to the threshold forming circuit, or on the use of electronic delays that prohibit the appearance of the output signal for the estimated contact jitter time.

In the known device for receiving signals from ¹⁵ turnip contacts, the effect of suppressing the effect of bounce is based on the integration of the input signal with the subsequent aggravation of the edges of the output signal [1] ^

A disadvantage of the known device is the low speed, the ability to work only with a certain type of contact, insensitivity to short-term signals with frequent and short bounce.

The closest technical solution to this invention is a device containing two synchronous triggers, an inverter, a normally open double-contact switch bus and two buses connected to a source of shifted clock signals [2].

A disadvantage of the known device is the low speed, the delay of the output two-contact switch, the inability to suppress bounce pulses in the control signals following one after another at short time intervals commensurate with the period of contact jitter frequency, since the necessary condition for the normal operation of this device is the choice of the clock frequency, the period of which should be commensurate with the Breaking rattle of contacts.

The aim of this invention is to improve performance in a wide

743131 the range of time ratios in the sequences of control signals and improving the accuracy of the formation of the output signals of the device to eliminate the influence of bounce from mechanical two-contact switches.

This goal is achieved by the fact that in the device for eliminating the influence of bounce from mechanical two-contact switches, containing a source of shifted clock signals, the first and second asynchronous triggers; the first input of the first asynchronous trigger is connected to the normally open contact bus, an OR element is additionally introduced. moreover, the first input of the second asynchronous' trigger is connected to the first input of the first asynchronous trigger, the corresponding output of which is connected to one of the inputs of the OR element, the other input of which is connected to the corresponding output of the second asynchronous trigger, and the second inputs of the first and second asynchronous triggers are connected respectively to the source of the shifted clock signals.

In FIG. 1 is a functional electrical diagram of a device for eliminating the influence of bounce from mechanical two-contact switches; in FIG. 2 - time diagrams of his work.

The device for eliminating the influence of bounce from mechanical two-contact switches contains asynchronous triggers (type US) .1,2: element OR 3, source bus of shifted clock signals 4,5 And normally-open two-contact switch 6..

A device for eliminating the influence of bounce from mechanical double-contact switches works as follows.

Prior to the closure of the contacts of the two-contact switch 6, both asynchronous triggers 1 and 2 are in the initial state, since buses 4 and 5 from the source of the shifted clock signals constantly receive clock signals with a frequency F (Fig. 2, a, b).

The first pulse of the bounce of the input signal that occurs when the contacts of the switch 6 are closed sets both asynchronous triggers 1 and 2 to state 1.

As can be seen from FIG. 2, asynchronous triggers 1 and 2, after setting them to the * 1 'state, are insensitive to the effects of subsequent bounce pulses until the asynchronous triggers are reset by the corresponding clock signals to state O. Since the clock signals coming to bus 4, 5 are shifted relative to the clock signals coming to bus 5, for half a period, i.e. Asynchronous triggers 1 and 2 are not set to state O at the same time, but with a time shift, 10 subsequent bounce pulses can affect only one of the two asynchronous triggers 1 and 2, and it is precisely the one that, by the time of the arrival of the next pulse, turned out to be already set to Ό * state. Asynchronous triggers are prepared to receive bounce pulses alternately and are transferred from state O to state 1 to 2Q as long as bounce pulses come from switch 6. The last pulse of bounce affects one of the asynchronous triggers (1 or 2), which at this point turned out to be set to state 'O'.

The output signals from asynchronous triggers 1 and 2 are fed to a two-way OR element 3, at the output of which there are no bounce pulses! ' 30 The output of the OR element 3 is the output of the device and from this output signals can be supplied to external electronic devices.

As can be seen from the timing diagram 35 (Fig. 2), the leading edge of the output signal coincides with the beginning of the action of the input signal (Fig. 2, c) i.e. with the first pulse of bounce, and the trailing edge of the output signal (Fig. 2, f) coincides with the 40 moment of the last reset to '0' of one of the asynchronous triggers 1 and 2. Do not let the delay value of the formation of the trailing edge of the output signal relative to the last pulse of bounce; - 45 provides the values of one period of the clock frequency.

The case considered corresponds to such a mode of operation in which _{50 an} input signal of a certain duration entirely consists of bounce pulses (which can be observed with very short-term trips of switch 6).

₅₅ When the contacts of circuit breaker 6 are closed for a long time and its contacts are subsequently opened, in the input signal, in addition to bounce pulses, there is a constant voltage level corresponding to the steady-state contact closure mode of the circuit breaker contacts. 6. The transmission of a constant level of the input signal from the input of the device to the output occurs without any distortion, since a constant zero level of the input signal keeps asynchronous triggers 1 and 2 in state 1, regardless of the action of the clock signals on the other inputs of the triggers (bus 4,5).

Thus, the device for eliminating the influence of bounce from mechanical two-contact switches eliminates bounce in the output signal, regardless of the duration of bounce when the contacts are closed and opened, and also regardless of the duration of holding the switch 6 in the closed state.

For proper operation of the device to eliminate the effect of bounce from mechanical two-contact switches, the frequency F of the clock signals must be selected from the condition

AND

F < ^- '

2 л lax.d, where T max. Dr. Is the maximum expected time gap between the adjacent 30 bounce pulses in the input signal.

The lower limit of the clock frequency should be selected from the condition

ABOUT

- frequency switching signal contacts of the switch;

- the duration of the input signal, taking into account the time of bounce.

Where

The duration of the clock pulses should be an order of magnitude shorter than the duration of the bounce pulses and sufficient for the stability of the reset in the state of asynchronous triggers 1 4 2.

Claims (2)

The diagrams of time relationships in the sequences of control signal of the controller and the increase in the accuracy of the formation of the output signals of the device to eliminate the influence of the bounce from mechanical two-contact switches. This goal is achieved by a Tvm that in the device to eliminate the influence of chatter from mechanical two contact switches, containing a source of shifted sync signals, the first and second asynchronous triggers; the first input of the first asynchronous trigger is connected to the bus of a normally open contact; an additional OR element is added, and the first input of the second asitron trigger is connected to the first input of the first asynchronous trigger, the corresponding output of which is connected to one of the inputs of the OR element, the other input is connected to the corresponding the output of the second asynchronous trigger, and the second inputs of the first and second asynchronous triggers are connected, respectively, to the source of the shifted sync signals. FIG. Figure 1 shows the functional electrical circuit of the device to eliminate the influence of chatter from the mechanical KI.H of two-contact switches; in fig. 2 - time diagrams of his work. The device for eliminating the influence of bounce from mechanical two-contact switches contains asynchronous triggers (of the TJS type) .1,2: element OR 3, the source bus of the shifted signal 1x 4.5 signals And the normal two-contact switch 6. A device for eliminating the influence of chatter from mechanical two-stroke switches operates as follows. Before closing the contacts of the two-contact switch 6, both asynchronous, flip-flops 1 and 2 are in the initial state, since the layers 4 and 5 from the source of the shifted sync signals always receive the sync signals with the frequency f (Fig. 2, a, b ). The first bounce pulse of the input signal, which occurs when the contacts of switch 6 are closed, sets both asynchronous triggers 1 and 2 to state 1. As can be seen from FIG. 2, asynchronous triggers 1 and 2, after they are set to state 1, are insensitive to the effects of the next 14 bursts of chatter until the acHiixpon flip-flops are reset by corresponding sync signals to state O. Since the clock signals coming to bus 4 are shifted relative to the clock signals received by the clock on the bus 4, the signals coming to the bus 4 are shifted relative to the clock signals received by the clock to the bus line 4. , on the poperiod, i.e. the installation of asynchronous triggers 1 and 2 in the state O does not occur simultaneously, but with a time shift, the subsequent bounce pulses can affect only one of the two asynchronous triggers 1 and 2 n exactly on that one, which by the moment of arrival of the next pulse the bounce turned out to be already set to the Q state, the Asynchronous triggers are prepared to receive the bounce pulses alternately and are transferred from the state O to the state 1 until the bounce pulses come from the switch 6. The last bounce pulse affects that of the asynchronous triggers (1 or 2), which by this moment turned out to be set to state O. Output signals from asynchronous triggers 1 and 2 are sent to the two-input element OR 3, at the output of which there are no bounce pulses. The output of the element OR 3 is the output of the device and from this output, signals can be fed to external electronic devices. As can be seen from the timing diagram (Fig. 2), the leading edge of the output signal coincides with the beginning of the input signal (Fig. 2, c), i.e. with the first bounce pulse, and the back edge of the output signal (Fig. 2, e) coincides with the time of the last reset to O of one of the asynchronous triggers 1 and 2. Refer back to the value of the delay of the back edge of the output signal; period of the frequency of the sync signals. The considered case corresponds to such a mode of operation in which the input signal of a certain duration consists entirely of bounce pulses (which can be observed with very short-term avg) (switches 6). With long-term closure of the contacts of the switch 6 and the subsequent opening of its contacts, in addition to the chattering pulses, the input voltage level corresponding to the steady-state closure of the switch contacts is present in the input signal. 6, Transmission of a constant input signal level from the device input to the output occurs without any distortion, since a constant zero input signal level keeps asynchronous triggers 1 and 2 in state 1, regardless of the effect of the sync signals on the other trigger inputs ( tires 4,5). Thus, a device for eliminating the influence of chatter from mechanical two-contact switches eliminates bounce in the output signal regardless of the duration of the chatter when closing and opening the contacts, as well as regardless of the duration of holding switch 6 in the closed state. For proper operation of the device to eliminate the influence of bounce from the mechanical two-contact. T-clock signal frequency should be selected from the condition 2 Tll.ax.dr where T max etc. is the maximum expected time gap between adjacent bounce pulses in the input signal. The lower limit of the clock frequency should be selected from the condition F. (t-%) switching frequency Signal contacts of the switch} - the duration of the input signal, taking into account the time of bounce. The duration of the signal, soy sync signals should be an order of magnitude shorter than the duration of the chattering pulses and sufficient for the stability of the reset. about asynchronous triggers 1 d 2. Claims of the invention A device for eliminating the influence of chatter from mechanical two-tact switches, containing a source of shifted sync signals, the first and second asynchronous triggers; The first input of the first asynchronous trigger is connected to the bus of a normally open contact, characterized in that, in order to increase speed in a wide range of time ratios in the sequences of control signals and to increase the accuracy of the formation of output signals, an OR element is added to it, the first input of the second asynchronous trigger is connected to the first input of the first asynchronous trigger, the corresponding output of which is connected to one of the inputs of the element OR the other input of which is connected Inen with the corresponding output of the second asynchronous trigger, and the second inputs of the first and second asin. synchronous triggers are connected respectively to the source of the shifted sync signals. Sources of information taken into account in the examination 1. Information leaflet of the All-Union Scientific Research Institute of Inter-Branch Information VIMI, No. 74, 2167. 2. Patent of Germany No. 1537443, l. 21 a 36/04, pub. 16.1O.69.