Digital-electronics 简明教程
7-Segment LED Display
当 LED (Light Emitting Diode) 正向偏置时，就会发出可见光或红外光。因此，它在各种电子器件中得到了广泛应用，例如电视屏幕、手机屏幕、手表和时钟、遥控器等。发光二极管 (LED) 当电流通经它时，基本上会将电能转换成光能。
LED (Light Emitting Diode) is a semiconductor device that emits either visible light or infrared light when it is forward biased. Thus, it is widely used in different electronic devices like TV screens, mobile screens, watches and clocks, remote controls, etc. A light emitting diode (LED) basically converts electrical energy into light energy when an electric current flows through it.
在本文中，我们将讨论 LED 在 Seven Segment Display 中的应用。七段显示器广泛用于不同的电子设备中，例如计算器、计数器、手表、电子测量仪器等。
In this article, we will discuss an application of LED in Seven Segment Display. The seven segment displays are extensively used in in different electronic gadgets like calculators, counters, watches, electronic measuring instruments, etc.
What is a Seven Segment LED Display?
Seven Segment Display 是基于 LED 的显示屏，可以以十进制数字的形式显示信息。七段显示器用于代替更复杂的点阵显示器。之所以这么称呼它，是因为它由七个发光二极管 (LED) 段组成，这些段像十进制 8 一样组装在一起，如下图所示。
Seven Segment Display is an LED based display screen that can display information in the form of decimal numbers. The seven segment display is a used in place of the more complex dot matrix displays. It is called so because it consists of seven segments of light emitting diodes (LEDs) that are assembled like decimal 8 as shown in the following figure.
七段 LED 显示器可用于需要电子显示器件以显示从 0 到 9 的十进制数字的应用中，有时也用于基本字符。由于它使用 LED，因此它是一种节能显示器件。因此，它最广泛应用于由小型电池或电芯供电的设备中。
Seven segments LED display can be used in applications where an electronic display device is required for showing decimal numbers from 0 to 9, sometimes, basic characters as well. Since, it uses LEDs, therefore it is an energy efficient display device. Therefore, it is most widely used in those devices that are powered by a small battery or a cell.
Working of Seven Segment LED Display
七段显示器由七个 LED 段组成，排列成十进制 8 的形状。这些 LED 段被点亮以形成一个图案，表示从 0 到 9 的十进制数字。现在，让我们了解七段 LED 显示器如何工作以显示不同的数字。
A seven segment display consists of seven LED segments arranged like a decimal 8. These LED segments are illuminated to form a pattern that represents a decimal number from 0 to 9. Now, let us understand, how the seven segment LED display work to display different numbers.
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When electrical energy is supplied to all the segments, then the seven segment LED display shows the decimal number 8.
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When power is given to all the segments and if we disconnect power from the segment ‘g’, then it displays the decimal number 0.
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When the power is given to segments "b" and "c" only, then it displays the number 1.
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When the power is given to the segments "a", "b", "g", "e", "d", then it displays the number 2.
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When the power is given to segments "a", "b", "g", "c", "d", then it displays the number 3.
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When the power is given to segments "b", "c", "f", "g", then it displays the number 4.
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When the power is given to segments "a", "c", "d", "f", "g", then it displays the number 5.
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When the power is given to segments "a", "c", "d", "e", "f", "g", then it displays the number 6.
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When the power is given to segments "a", "b", "c", then it displays the number 7.
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When the power is given to segments "a", "b", "c", "d", "f", "g", then it displays the number 9.
通过照亮七段 LED 显示屏的一组 LED 段，我们可以显示从 0 到 9 的任何十进制数字。
In this way, we can display any decimal number from 0 to 9 by illuminating a set of LED segments of the seven segment LED display.
Truth Table of Seven Segment LED Display
下表显示了七段 LED 显示屏的真值表，用于显示从 0 到 9 的十进制数字。
The following table shows the truth table of a seven segment LED display to display the decimal numbers from 0 to 9.
Seven Segment Display Output |
LED Segments Inputs |
a |
b |
c |
d |
e |
f |
g |
0 |
1 |
1 |
1 |
1 |
1 |
1 |
0 |
1 |
0 |
1 |
1 |
0 |
0 |
0 |
0 |
2 |
1 |
1 |
0 |
1 |
1 |
0 |
1 |
3 |
1 |
1 |
1 |
1 |
0 |
0 |
1 |
4 |
0 |
1 |
1 |
0 |
0 |
1 |
1 |
5 |
1 |
0 |
1 |
1 |
0 |
1 |
1 |
6 |
1 |
0 |
1 |
1 |
1 |
1 |
1 |
7 |
1 |
1 |
1 |
0 |
0 |
0 |
0 |
8 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
9 |
1 |
1 |
1 |
1 |
0 |
1 |
Types of Seven Segment LED Displays
有两种类型的七段显示屏可用−
There are two types of seven segment displays available −
Common Cathode Seven Segment Display
在这种类型的七段显示屏中，所有 LED 段的阴极端子连接到逻辑 0（较低电压电平）。通过限流电阻施加逻辑 1（较高电压电平）以正向偏置各个 LED 段在其阳极端子处。
In this type of seven segment display, the cathode terminal of all LED segments are connected together to logic 0 (lower voltage level). The logic 1 (higher voltage level) is applied through a current limiting resistor to forward bias the individual LED segments at their anode terminals.
Common Anode Seven Segment Display
在这种类型的七段 LED 显示屏中，所有 LED 段的阳极端子连接到逻辑 1（较高电压电平），并且通过限流电阻将逻辑 0（较低电压电平）用于 LED 段各个阴极端子。
In this type of seven segment LED display, the anode terminals of all the LED segments are connected together to the logic 1 (higher voltage level), and the logic 0 (lower voltage level) is used through a current limiting resistor to the individual cathode terminals of LED segments.
Note −共阳极七段 LED 显示屏比共阴极七段显示屏更流行，因为与它们可以提供的电流相比，逻辑电路可以吸收更高的电流。
Note − Common Anode Seven Segment LED Displays are more popular than Common Cathode Seven Segment Display because logic circuit can sink higher current as compared to they can source.
Applications of Seven Segment LED Displays
七段 LED 显示屏广泛用于以下设备中−
Seven Segment LED Displays are widely used in the following devices −
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Digital watches and clocks
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Calculators
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Microwaves
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Remote controls
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Speedometers
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Vehicle odometers
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Clock radios, etc.
Conclusion
七段显示屏非常普遍地用于低功耗电子设备中，例如遥控器、手表、时钟、数字测量仪器等。从以上的讨论中，我们可以得出结论：七段显示屏由七个 LED（发光二极管）段组成，这些段以特定的方式被照亮以显示数字 0 到 9。七段显示屏还用于显示一些基本字符。
Seven segment displays are very commonly used in low power electronic devices like remote controls, watches, clocks, digit measuring instruments, etc. From the above discussion, we may conclude that a seven segment display consists of seven LED (Light Emitting Diode) segments that are illuminated in a pattern to display the numbers from 0 to 9. Seven segment displays are also used to display some basic characters.