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Barcode Reader Working Principle
Step-by-step breakdown:
Light emission: A barcode reader emits a beam of light across the barcode. Some scanners use a laser, while others use an LED or a camera. Light reflection: The white spaces of the barcode reflect the light, while the black bars absorb it. Signal detection: A light sensor or camera detects the pattern of reflected light. The intensity of the reflected light changes as the scanner moves across the black and white bars. Signal conversion: The sensor converts this pattern of light into an electrical signal. The electrical currents correspond to the widths and sequence of the bars and spaces. Decoding: A built-in decoder analyzes the electrical signal, interprets the pattern based on the barcode's standard, and converts it into digital data (binary 0s and 1s). Data transmission: The digital data is then sent to a connected device, such as a computer or point-of-sale system, where it can be displayed as product information, a price, or other data.
What is OCR? OCR stands for Optical Character Recognition. It is the procedure that transforms a text image into a text format that can be read by computers. Your computer will save the scan as an image file, for instance, if you scan an invoice or a receipt. The phrases contained in the image file cannot be edited, searched for or counted using a text editor. The image can be transformed into a text file with its contents saved as text data using OCR. Applications of OCR
Mobile Banking Applications: Applications of mobile banking use OCR to capture and recover data from cheques for deposit. Healthcare records: OCR is used in the healthcare department to manage the information of the patient so that healthcare facilities can be Scanners for business cards: Apps with OCR capabilities can scan cards for business and save contacts right into the consumer's address book. Recognition of License plate number: OCR technology is used by parking lots and law enforcement to read and recognize license plates for safety and parking management. Mails: Sorting and processing of mail according to addresses and ZIP codes is done automatically by postal services using OCR. accessed quickly.
Monitors
Cathod Ray Tube (CRT)
Polarizing filters: Two polarizing filters are placed on either side of the liquid crystal layer. The first filter polarizes the light from the backlight, and the second is oriented at a 90-degree angle to the first. Liquid crystals: These are sandwiched between the filters and can have their orientation changed by an electric current. No current: The liquid crystals naturally twist the light, allowing it to pass through the second, perpendicular filter. With current: The electric field untwists the liquid crystals, blocking the light from passing through the second filter. Color filters and pixels: Each pixel is divided into three sub-pixels (red, green, and blue). The color filters allow only one color of light to pass through each sub-pixel. Thin-film transistors (TFTs): Modern LCDs use a transistor for each sub-pixel to provide precise and fast control over the electric current, allowing for a sharp, clear image.
Passive Matrix & Active Matrix
Passive matrix LCDs use a simple grid of horizontal and vertical conductors to control pixels, but only one row can be addressed at a time, leading to slow response times and low contrast. In contrast, active matrix LCDs use a transistor at each pixel to precisely control its state, allowing for faster refresh rates, higher contrast, and better color reproduction, though they consume more energy.
Passive matrix LCD
How it works: A grid of horizontal and vertical conductors made of Indium Tin Oxide (ITO) controls the pixels. A pixel is addressed when a voltage is applied to the correct row and column intersection. Limitation: Only one row can be addressed at a time, so the display must be refreshed sequentially. This results in slow response times and can cause image ghosting.
Applications: Primarily used in low-cost, low-power monochrome displays like calculators and watches.
Active matrix LCD
How it works: Each pixel has its own dedicated thin-film transistor (TFT) and capacitor. The transistor acts as a switch, allowing for precise and constant voltage control for each individual pixel. Advantage: The dedicated transistor keeps the pixel's state held between refresh cycles, leading to a much faster response time, higher contrast, and better overall image quality. Applications: Used for higher-quality color displays, such as those in laptops, smartphones, and televisions.
Printers
Printers create a physical copy of a digital document by translating the file into instructions for placing dots of ink or toner onto paper.
For an inkjet printer, tiny nozzles spray liquid ink onto the page. For a laser printer, a laser charges a drum, which attracts powdered toner that is then transferred to paper and heated to fuse the image permanently.
Working:
- Data sent to the printer: When you click "print," your computer sends a digital file to the printer.
- File conversion: A printer driver converts the file into a format the printer understands, creating a pattern of dots that will make up the image or text.
- Inkjet process: o A print head with tiny nozzles moves across the paper.
o Print Quality: Generally lower print quality. o Speed: Slower than non-impact printers. o Cost: Often lower initial cost, but can have long-term costs for ribbons. o Specialty: Can print on multipart forms (like carbon copies). Examples: Dot-matrix, daisy wheel, and line printers.
Non-Impact Printers
Mechanism: Create images without physical contact. Common methods include using lasers, spraying ink (inkjet), or heat (thermal).
Characteristics: o Noise : Quiet, with the only sound being the motor. o Print Quality: Higher print quality and resolution. o Speed: Faster printing speed. o Cost: Generally more expensive upfront. o Specialty: Can handle a variety of fonts and graphics with ease. Examples: Laser, inkjet, and thermal printers.
