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en:iot-open:hardware2:actuators_light [2023/11/21 21:41] – ktokarz | en:iot-open:hardware2:actuators_light [2023/11/23 10:39] (current) – pczekalski | ||
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====== Optical Output Devices ====== | ====== Optical Output Devices ====== | ||
+ | {{: | ||
== Light-Emitting Diode == | == Light-Emitting Diode == | ||
Unlike the other diodes, the light-emitting diode, also called LED, is a particular type that emits light. LED has an entirely different body, which is made of transparent plastic that protects the diode and lets it emit light (figure {{ref> | Unlike the other diodes, the light-emitting diode, also called LED, is a particular type that emits light. LED has an entirely different body, which is made of transparent plastic that protects the diode and lets it emit light (figure {{ref> | ||
- | * The cathode' | + | * the cathode' |
- | * The anode' | + | * the anode' |
<figure led1> | <figure led1> | ||
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* //U// – Combined voltage for LED and resistor. | * //U// – Combined voltage for LED and resistor. | ||
- | To calculate the resistance | + | A short guide on calculating |
- Find out the voltage needed for the diode to work //U_D//; you can find it in the diode parameters table. | - Find out the voltage needed for the diode to work //U_D//; you can find it in the diode parameters table. | ||
- Find out the amperage needed for the LED to shine //I_D//; it can be found in the LEDs datasheet, but if you can't find it, then 20 mA current is usually a correct and safe choice. | - Find out the amperage needed for the LED to shine //I_D//; it can be found in the LEDs datasheet, but if you can't find it, then 20 mA current is usually a correct and safe choice. | ||
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== Digital LED == | == Digital LED == | ||
- | Digital LED does not have anode or cathode connections available externally. They have power supply pins and two pins for data transmission, | + | Digital LED does not have anode or cathode connections available externally. They have power supply pins and two pins for data transmission, |
<figure smartled1> | <figure smartled1> | ||
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* electronic ink display (E-ink). | * electronic ink display (E-ink). | ||
- | **7-segment LED display** | + | **7-segment LED display**\\ |
The seven-segment LED display is built with seven LEDs forming the shape, making it possible to display symbols similar to digits and even some letters. Usually, the eighth LED is added as the decimal point. 7-segment displays can have similar internal connections as RGB LEDs, common anode or common cathode. If there is more than one digit in the element, all the same segments are also connected. Such displays need special controllers or the software part that displays separate digits in a sequence one by one. To avoid unnecessary blinking or differences in the brightness of digits, software for sequential displays is written using timers and interrupts. As for the RGB LEDs, 7-segment displays need a separate resistor for every segment. Sample 2-digit 7-segment module is present in the figure {{ref> | The seven-segment LED display is built with seven LEDs forming the shape, making it possible to display symbols similar to digits and even some letters. Usually, the eighth LED is added as the decimal point. 7-segment displays can have similar internal connections as RGB LEDs, common anode or common cathode. If there is more than one digit in the element, all the same segments are also connected. Such displays need special controllers or the software part that displays separate digits in a sequence one by one. To avoid unnecessary blinking or differences in the brightness of digits, software for sequential displays is written using timers and interrupts. As for the RGB LEDs, 7-segment displays need a separate resistor for every segment. Sample 2-digit 7-segment module is present in the figure {{ref> | ||
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- | **LED matrix display** | + | **LED matrix display**\\ |
LED matrix displays offer the possibility of displaying not only digits and letters but also pictograms and symbols. The most popular versions have 8 rows and 8 columns (figure {{ref> | LED matrix displays offer the possibility of displaying not only digits and letters but also pictograms and symbols. The most popular versions have 8 rows and 8 columns (figure {{ref> | ||
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</ | </ | ||
- | **Liquid-Crystal Display (LCD)** | + | **Liquid-Crystal Display (LCD)**\\ |
Monochrome LCD uses modulating properties of liquid crystal to block the passing-through light. Thus, when a voltage is applied to a pixel, it is dark. A display consists of layers of electrodes, polarising filters, liquid crystals and a reflector or backlight. Liquid crystals do not emit light directly but through reflection or backlight. Because of this reason, they are more energy efficient. Small, monochrome LCDs are widely used to show little numerical or textual information like temperature, | Monochrome LCD uses modulating properties of liquid crystal to block the passing-through light. Thus, when a voltage is applied to a pixel, it is dark. A display consists of layers of electrodes, polarising filters, liquid crystals and a reflector or backlight. Liquid crystals do not emit light directly but through reflection or backlight. Because of this reason, they are more energy efficient. Small, monochrome LCDs are widely used to show little numerical or textual information like temperature, | ||
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</ | </ | ||
- | **Organic Light-Emitting Diode Display (OLED)** | + | **Organic Light-Emitting Diode Display (OLED)**\\ |
OLED display uses electroluminescent materials that emit light when the current passes through these materials. The display consists of two electrodes and a layer of an organic compound. OLED displays are thinner than LCDs, have higher contrast, and can be more energy efficient depending on usage (figure {{ref> | OLED display uses electroluminescent materials that emit light when the current passes through these materials. The display consists of two electrodes and a layer of an organic compound. OLED displays are thinner than LCDs, have higher contrast, and can be more energy efficient depending on usage (figure {{ref> | ||
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- | **Monochrome Electronic Ink Displays (E-Ink)** | + | **Monochrome Electronic Ink Displays (E-Ink)**\\ |
E-ink display uses charged particles to create a paper-like effect. The display comprises transparent microcapsules filled with oppositely charged white and black particles between electrodes. Charged particles change their location depending on the orientation of the electric field; thus, individual pixels can be either black or white (figure {{ref> | E-ink display uses charged particles to create a paper-like effect. The display comprises transparent microcapsules filled with oppositely charged white and black particles between electrodes. Charged particles change their location depending on the orientation of the electric field; thus, individual pixels can be either black or white (figure {{ref> | ||
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</ | </ | ||
- | ** Colourful e-Ink displays ** | + | ** Colourful e-Ink displays **\\ |
Recent advances in E-Ink (E-Paper) technology present the ability to display coloured information. Various approaches are present in the engineering of colourful E-Ink displays, along with multiple technologies for the presentation of colours. | Recent advances in E-Ink (E-Paper) technology present the ability to display coloured information. Various approaches are present in the engineering of colourful E-Ink displays, along with multiple technologies for the presentation of colours. | ||
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Opposite to the above, multicolour e-Ink displays provide a true selection of colours per pixel and are implemented in various technologies presented below. | Opposite to the above, multicolour e-Ink displays provide a true selection of colours per pixel and are implemented in various technologies presented below. | ||
- | Multicolour with filtering.\\ | + | **Multicolour with filtering**\\ |
In this construction, | In this construction, | ||
< | < | ||
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</ | </ | ||
- | Multicoloured capsules in a single sphere (ACEP Advanced Colour ePaper).\\ | + | **Multicoloured capsules in a single sphere (ACEP Advanced Colour ePaper)**\\ |
In this approach, capsules in a single sphere are multicoloured rather than black-white. Microcapsules of different colours have slightly different charging, so a variating external electric field applied to the single sphere controls the colour of the capsules on the top of the sphere that is visible to the user. A single sphere can then present a wide range of colours. This kind of display uses subtractive colour mixing (CMY/CMYK). A principle of operation is present in figure {{ref> | In this approach, capsules in a single sphere are multicoloured rather than black-white. Microcapsules of different colours have slightly different charging, so a variating external electric field applied to the single sphere controls the colour of the capsules on the top of the sphere that is visible to the user. A single sphere can then present a wide range of colours. This kind of display uses subtractive colour mixing (CMY/CMYK). A principle of operation is present in figure {{ref> | ||
< | < | ||
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</ | </ | ||
- | Multicoloured capsules in separate spheres.\\ | + | **Multicoloured capsules in separate spheres**\\ |
This approach is theoretical as manufacturing such devices is inefficient because of the need to compose a matrix of spheres with different colours of microcapsules nearby. A domain of such spheres composes a single pixel. A principle of operation is present in figure {{ref> | This approach is theoretical as manufacturing such devices is inefficient because of the need to compose a matrix of spheres with different colours of microcapsules nearby. A domain of such spheres composes a single pixel. A principle of operation is present in figure {{ref> | ||