Electronic indicator

An electronic indicator helps a person quickly and clearly assess the necessary parameters, especially those that a person cannot directly determine with the help of his own sense organs ^[1] . If high accuracy of such an assessment is required, multi-digit digital indicators are installed; in cases where accuracy is not required and it is necessary to see only the presence or absence of a signal, single indicators are used.

The assignment of certain devices to the indicators is determined by their use. For example, an ordinary incandescent bulb, designed for lighting, when used in warning systems or control and monitoring panels, can be considered an indicator. At the same time, an electronic scoreboard made from matrix LEDs and used for advertising is no longer considered an indicator. Thus, the name "electronic indicator" is often determined not only by the design or physical features of the product, but by the method of its application in a specific device or system.

The concept of an electronic indicator combines many different devices and the classification can be performed according to various criteria - design features, control methods and purpose. In the literature there are various ways to classify indicators:

To destination - depending on the size and place of installation:

• individual
• group
• collective use

According to the physical principle of image formation :

• Active - semiconductor ( LED ), gas-discharge , cathodoluminescent , electroluminescent , incandescent - all those that in the process emit light to form the image.
• Passive - devices that form an image by polarization, reflection or transmission of light from an external source. Passive include liquid crystal , electrophoresis , electrochromic , and also ferroelectric indicators ^[2] .

By the nature of the information displayed :

• Single - a separate indicator in the form of a point or a geometric figure, which does not carry any information by its form and conveys the state by its presence, color or brightness.
• Scale - a discrete indicator designed to display information in the form of levels or values, is performed in the form of several individual indicators located along a straight line (linear scale indicator) or a curvilinear form. Transmits information by the number or position of the display elements on the scale.
• Mnemonic - a separate indicator in the form of a geometric figure or image, the shape of which is important for the interpretation of the displayed information.
• Digital - an indicator that displays the values ​​of a numerical value in digital form.
• Alphanumeric - designed to display numbers, letters and special characters. Alphanumeric indicators display either the limited list of symbols incorporated when developing a device, or it gives the opportunity to create images of symbols independently. Often such an indicator is called alphanumeric.
• Graphic is the most complex type of indicators, which allows to transmit both symbolic information and pictures.
• Combined - an indicator that combines two or more options of displayed information. Combined indicators are often used in consumer or portable mass-produced equipment, since they are often unique and are developed for each type of device separately.

According to the design of the information field :

• Introduce ^[2] - an indicator that contains several symbols or signs embedded in the design. The choice of a particular image is made by the appropriate control schemes. Vacuum filament or gas-discharge indicators work on this principle.
• The sign - synthesizing indicator is an indicator in which information intended for visual perception is displayed using one or a set of discrete elements. For example, all segmental indicators, including seven-segment , and matrix indicators , are signs of synthesizing.

According to the information capacity :

• Single bit - designed for a single digit or character.
• Multi-bit with fixed familiarity - designed to display multiple numbers or symbols.
• Multi-bit without fixed familiarity - usually matrix graphic indicators designed to display characters anywhere in the information field.

By the method of forming the image :

• Static - devices in which each display element has its own control scheme. The state of each element is unique at each moment of time and adequately corresponds to the image perceived by the person. At the same time, the method of transmitting information to the circuit element that determines the state does not matter and can be including multiplexed.
• Multiplexed , or dynamic ^[2] - indicators, in which the image at each time moment contains only a part of complete information, and the resulting picture is perceived by the human eye in full due to the inertia of view or due to the inertia of display elements. Such a scheme is used, for example, in matrix indicators and in multi-digit seven-segment indicators, when the outputs of the display elements are combined with each other to simplify the control circuit.

By color :

• Monochrome - whose color is determined by the design.
• Multi - color - indicators that have the ability to transmit information in different colors or shades of color. Usually have a limited number of transmitted colors. A typical example would be hazard indicators, which in their normal state are green, and in the case requiring attention, yellow or red.
• Full - color - indicators that have the ability to transfer all shades of color perceived by the human eye.

By way of information transfer :

• analog - transmit information by the brightness or shade of color.
• discrete - transmit information by the number and set of elements.

In addition to the listed classification features, electronic indicators are distinguished:

• By height and width of the mark
• By viewing angle and radiation pattern
• By the brightness of the display elements and by the average brightness - the brightness of the surface
• By uneven brightness of display elements
• By the brightness of its own background (contrast)
• By width and features of the emission spectrum
• Wavelength at maximum radiation
• By the reaction time of the display elements (on-time)
• By the relaxation time of the display elements (off time)

In addition, by voltage, readiness time, critical frequency, lifetime, and other specific features.

Industry produces a wide variety of indicators - universal, as well as designed and intended for installation in a specific product. Among the large number of types of indicators, there are several most commonly used:

Unit Indicators

Single indicators are very common. LED indicators or neon bulbs are built into light switches, household appliances, and various equipment. The main purpose of such devices is to indicate the status or to attract attention. A single indicator can be considered the most reliable of all types of indicators due to the smallest number of elements and the simplicity of the control scheme.

Matrix Indicators

The matrix indicator is a kind of symbol-synthesis indicator in which the display elements are grouped in rows and columns. The matrix indicator is designed to display symbols, special characters and graphic images in various devices. Unlike the screen or display, the indicator has a limited number of display elements, or it is designed to display one or a small number of characters. The smallest element of a matrix indicator image is called a pixel . Each pixel can consist of one or several single display elements operating simultaneously.

Matrix indicators are available in various types:

• Semiconductor (LED)
• Liquid crystal
• Fluorescent

Different format. Most used:

• 5 x 7 pixels
• 5 * 8 pixels
• 8 * 8 pixels
• 16 * 16 pixels

According to the method of imaging matrix indicators are of two types: static and multiplex (dynamic). The most commonly used multiplexed control method is when the same outputs of each element of the image are combined in the rows of the indicator, and the opposite conclusions in the columns (or vice versa). For example, in the LED indicator with this control method, the supply voltage is alternately applied to the columns (or to the rows), and the code defining the state of all its elements to the rows (or, respectively, the columns). In the same way, an image is formed on the rest of the indicator. In order for the human eye to perceive information without flickering, the entire cycle of updating information must be less than the reaction time of the eye (10-20 milliseconds) ^[3] .

Segment Indicators

A segmental indicator is an indicator whose display elements are segments grouped into one or more familiarity. A segment is a display element of the information of a symbol-synthesizing indicator, the contour of which is straight and (or) curved lines. Unlike the matrix indicator, in which all elements of the image are the same in shape, in the segment indicator each segment is unique. The shape and position of the segments on the indicator is designed specifically for the transfer of a specific set of characters or characters. The symbols on such indicators are formed by a combination of several segments. The main difference between a segment indicator and a matrix is ​​a relatively small number of display elements and, accordingly, a simplified control circuit.

Two types of segment indicators are most commonly used:

• Digital seven-segment indicators having seven elements — segments for displaying a digit, and possibly an additional one for indicating a point.
• Alphanumeric indicators with nine , fourteen or sixteen segments. Such indicators have the ability to show most of the characters of the Latin and Russian alphabet, not counting the numbers and special characters.

Scale Indicators

The indicator indicator is a symbolic indicating instrument designed to visually display levels or magnitudes as a quantity or position of display elements on a discrete scale. The gauge indicators are widely used in household appliances and electronics to indicate the battery charge level, the temperature of the heating element, the power of the cellular signal, and everywhere where high accuracy of readings is not required. The dial indicator has gained widespread acceptance, since it allows us very well and clearly to estimate the value of the desired parameter. For additional information, different parts of the bar indicator can be made in different colors.

The control of the scale indicator is performed most often in a static way, in the case of using a combination of several scale indicators, for example, in musical equipment, the control is carried out by a multiplex method.

General indicators differ by the way information is transmitted:

• With filling - when the signal level is shown by a set of consecutive elements from the first to the most significant.
• Without filling - when the signal level is indicated by the position of one or several adjacent display elements.
• Peak - when the average signal level is shown with a scale with filling, and the peak (maximum) value - with one element, often of a different color ^[4] .

Electromechanical display devices - blinker and electromechanical bistable boards are positioned somewhat separately from electronic indicators. In terms of image formation and application, such products resemble the indicators listed above. They belong to the sign-synthesizing digital or alphanumeric devices with the passive image formation principle (reflection of incident light), but contain mechanical elements, the position and method of switching of which depends on the product design. Blinker boards have one significant feature - they consume energy only at the moment of switching (state change).

Since the physical principle of imaging is based on the reflection of light from a special reflective coating and, consequently, this image is not the result of an electronic effect, electronic mechanical indicators do not belong to electronic indicators.

• Odometer

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• N.I. Vukolov, A.N. Mikhailov. Signs Synthesizing Indicators / ed. V.P. Balashov. - M .: Radio and communication, 1987. - 592 p.
• GOST 25066–91 “Signs synthesizing indicators. Terms, definitions and lettering
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