RU2269815C2 - Method for controlling serviceability of a keyboard - Google Patents

Abstract

FIELD: electric engineering, in particular, technology for controlling serviceability of controlling and commutating elements of electric circuits, possible use for controlling state of panels for controlling electro-mechanical devices in form of separate keys or switches, and also key-based information input devices in form of keyboards.

SUBSTANCE: method includes forming a series of testing pulses of current with given amplitude and length, sent to each piezoelectric element of key, value of resulting voltage component variable in stabilized state is measured, result of measurement is compared to given maximal and minimal boundary values.

EFFECT: possible detection in real time scale of breakdowns in form of dents or destruction of piezoelectric element crystal, violation of integrity of contact connections and conductors, both before and during process of information accumulation; increased reliability of keyboard.

Description

The control method relates to electrical engineering and, in particular, to monitoring the operability of control elements and switching electrical circuits and can be used to monitor the status of control panels of electrical devices in the form of separate switches (keys) or keyboards for entering discrete information.

A known control method implemented in the keyboard of a personal computer (RF Patent No. 2121707, G 06 F 3/023. Publ. October 27, 2002, Bull. No. 30), which consists in the fact that depending on the mode included form commands in the form of voltage pulses , converted using the electronic circuit of the key into the code of its indicator, on which an image of that sign or symbol is displayed that is displayed on the monitor and is written to the computer’s memory when this key is pressed. By comparing the information on the indicator and the monitor, the keyboard operability is determined. A known control method based on the presentation of visual information (RF Application No. 2002125870, G 06 F 3/023. Publication date 02/20/2004) by means of an electronic device containing a display and a numeric keypad with keys. In this method, visual information is presented on the display in sections, each of which is associated with one of the keys of the numeric keypad, and visual indication of the key selection is performed on the numeric keypad.

The disadvantages of both of these methods is the long time required to compare the information on the keys and on the display, which leads to an increase in the length of the process of entering information and the operator’s quick fatigue; delay in information about the occurrence of failure (s) in the keyboard, because its presence is detected only after a set of information.

To reduce the time of comparing information and reduce operator fatigue, a way to control the information typed on the keyboard, i.e. the way to monitor its performance (RF Patent No. 2096820, G 06 F 3/02. Publ. 04/20/2002, Bull. No. 11), which consists in the fact that they monitor the performance of the keyboard using visual and auditory channels, which reduces the harmful effects of the monitor vision and increases labor productivity. The main disadvantage of this method is the low reliability due to the delay in information about the occurrence of a failure in the keyboard with identifying it only after typing on the keyboard with checking the passage of information visually on the monitor or by ear.

A known control method implemented in a device for controlling a keyboard (SU No. 1432525, G 06 F 11/00. Publ. 23.10.88, Bull. No. 39), which consists in the fact that when a key is pressed, a code is generated that is compared with the reference code , and according to the results of the comparison, an error is detected in the set of information (single press) or the presence of a keyboard malfunction (repeated press). The disadvantage of this control method is its low reliability, since a failure that occurs is detected with delay after a set of information and only after pressing the key twice.

A known method of monitoring the health of piezoelectric elements (SU No. 481119, H 03 h 3/00. Publ. 15.08.75, Bull. No. 30), selected as a prototype. The prototype method consists in determining the parameters of the piezoelectric elements due to the formation of two antipolar test current pulses having a specified duration and supplied to the piezoelectric element, with the analysis of the time dependence of the voltage on the piezoelectric element.

The main disadvantage of the prototype method is its low reliability, due to two reasons - the lack of conditions for real-time monitoring before dialing and when typing information and the possibility of false information about an element failure during typing and after typing. The first one arises because during testing a bipolar signal is received on an element without a constant component with an increased swing, which makes it close in shape and level to a useful signal received when a key is pressed (both signals are difficult to distinguish). The second is caused by the unsteadiness of the signal on the element during testing, which manifests itself in a decrease in amplitude in time, which does not allow comparing the result of measuring it with predetermined boundary values.

The technical result of the invention is to increase reliability by detecting a failure in the keyboard in real time before dialing and during the process of gathering information and the absence of false positives, since the analyzed signal having a constant component differs in form and level from the useful signal caused by pressing a key , and in the steady state it is almost stationary with constant amplitude.

The specified technical result is achieved as follows. In relation to the known method for monitoring keyboard operability, performed mainly on piezoelectric elements by the number of keys, in the proposed method, a sequence of test current pulses of a given amplitude and duration is supplied to each piezoelectric element, which measures the value of the obtained voltage component in steady state, and the measurement result is compared with the specified maximum and minimum boundary values.

Consider the keyboard with the proposed control method. The keyboard contains either a single key or a set of them with piezoelectric elements according to the number of keys. When a piezoelectric element is exposed to a mechanical force that causes stress in the material, it generates an electrical signal that disappears when the force is removed, and as a result, a voltage pulse is generated from its contacts, causing the actuator to trigger or input the corresponding information. However, under mechanical or climatic influences, these elements can partially (chip part of the crystal) or completely collapse, or they may break the integrity (open or short circuit) of contact connections - lead-in conductors and current collector contacts. These failures cause a loss of keyboard functionality. They are usually found after entering information and identifying its distortions (the input and input information is compared).

The proposed control method is based on the fact that the equivalent circuit of the piezoelectric element contains a capacitor, the capacitance of which is a controlled parameter, since it depends on the size and state of the crystal. When a crystal is destroyed, the capacitance decreases in proportion to the size of its remainder with current-collecting contacts, and when they break, it becomes practically equal to zero. To implement the control method, a sequence of test current pulses is generated, which are supplied to each piezoelectric element (all at once or in turn) within an interval with a duration selected depending on the pulse repetition rate and sufficient to switch to the stationary (static) mode of the circuit capacitor recharging substitution. The resulting alternating voltage component of the piezoelectric element is a sequence of pulses, the shape and amplitude of which are determined by the charge-discharge rate and depend on the amplitude and duration of the supplied test current pulses, for example, a rectangular shape and the capacitance of an equivalent capacitor, which together with the output resistance of the generator forms an integrating circuit . In this case, the shape of the pulses is close to triangular, or with a very small capacitance it becomes almost identical to the shape of the test pulses, and with a short circuit of the contacts, the pulses disappear. The charge-discharge should occur under the condition that the ampere-second areas of the current pulses are equal through the piezoelectric element (through the equivalent capacitor), in which case the average value of the variable component of the voltage on the element will be constant (positive, negative or zero). The amplitude value or the magnitude of this voltage component is measured and compared with the permissible maximum and minimum boundary values. If the amplitude does not exceed the limit (tolerance) value, then the capacitance of the equivalent capacitor is normal, and the piezoelectric element is operational. If the value of the variable component exceeds the limit level, then the capacitance is unacceptably small, if it has a zero value, then a short circuit occurs, which ultimately corresponds to a faulty piezoelectric element and an inoperative keyboard. When tuning, the parameters of the testing pulses are selected (amplitude, duration, pulse repetition rate and pause between them) and at the same time they provide such a value of the variable component that must be within the specified limits and be significantly less than the amplitude of the useful signal taken from the piezoelectric element when the key is pressed. The latter circumstance allows you to test the keyboard in real time both before typing, and during typing, since the test signal does not create significant interference when detecting a useful signal. Monitoring is carried out in manual and automatic modes, and based on its results, an indication of a detected failure and / or the connection of an additional backup key, set of keys or keyboard are possible.

Thus, in the proposed method for monitoring the keyboard operability, performed mainly on piezoelectric elements by the number of keys, the following has been achieved. It became possible to detect failures in the form of chips or the destruction of the crystal of the piezoelectric element, integrity failures (open circuit, short circuit) of contact joints and lead wires without an operator’s participation both before and after dialing in real time during testing the process of gathering information. When a keyboard malfunction is detected, a warning indication and / or manual or automatic connection of backup keys (if necessary, another keyboard) can be carried out, which ultimately increases the reliability of the keyboard.

Claims (1)

A method for monitoring the operability of a keyboard made primarily on piezoelectric elements by the number of keys, characterized in that a sequence of test current pulses of a given amplitude and duration is supplied to each piezoelectric element, on which the value of the obtained variable voltage component is measured in steady state, and the measurement result is compared with given maximum and minimum boundary values.