What is a black and white LCD screen (monochrome screen)?
Black and white LCD screen is a display technology that focuses on functionality and practicality It is not a "low-end version " of color screens, but the optimal solution for specific scenarios with extremely high cost
The previous article introduced TFT LCD, today we will explain in detail the black and white LCD screen, which is also commonly referred to as monochrome LCD screen.
Simply put, this is a type of LCD screen that can only display a single color (usually black, blue, white, etc.), and the displayed image has no color changes, only the difference between bright and dark areas (i.e. gray levels).
1. Core Features
Single color: Unlike the color screens on our phones and computers that can display millions of colors, black and white screens usually only display one basic color and its different shades. The most common combinations are:
White background with black text (prominently displayed)
Black background with white text (negative display)
white text on a blue background
Yellow green background with black text (the color of classic calculators and old-fashioned electronic watches)
Grayscale display: Advanced black and white screens support different levels of grayscale, which can display simple images, icons, or smoother transitions, rather than just pure text and lines.
Relatively simple structure: Due to the absence of the key component of color filters, its structure is much simpler than that of color LCD screens.
2. Working principle (comparison with color LCD)
For a better understanding, we can compare it with color TFT LCD:
Feature | Black and white LCD screen | |
core structure | Backlight panel+lower polarizer+liquid crystal layer+upper polarizer | Backlight board+lower polarizer+TFT array+liquid crystal layer+color filter+upper polarizer |
Color development principle | By twisting liquid crystal molecules, light is controlled to "pass" or "block", forming bright and dark areas. | By precisely controlling the LCD of each sub-pixel through TFT, the backlight is mixed with various colors through red, green, and blue filters. |
Pixel composition | One pixel is a complete control unit. | A pixel is composed of three sub pixels: red, green, and blue. |
The key difference lies in the "color filter":
Black and white screens do not have color filters, so after the backlight (usually white LED) passes through the liquid crystal layer, it is directly filtered by the upper polarizer, forming a bright or dark effect. And each pixel of the color screen must be divided into three sub pixels, corresponding to red, green, and blue color filters, to produce a full-color effect by mixing the brightness of these three colors.
3. Main driving technology types
Black and white LCD screens are mainly divided into the following categories based on their driving and control methods:
Segment LCD
Description: This is the simplest and most common type. The display content is fixedly divided into several "segments" (such as strokes of numbers, fixed icon symbols).
Features: Extremely low cost, very low power consumption, simple development.
Applications: Calculator, electronic scale, multimeter, home appliance (air conditioner, microwave oven) display screen.
Dot matrix display
Description: Pixels are arranged in a matrix (rows and columns), allowing for free control of the brightness of each point, thereby displaying any character, graphic, or even simple image.
Features: Flexible display content, requiring specialized driver chips (such as COG technology that directly binds the chip to glass).
Classification:
Character dot matrix screen: mainly used for displaying text and standard characters.
Graphic dot matrix screen: can display any graphics and custom images.
4.Advantages and disadvantages
Advantages:
Low cost: The structure is simple, and the raw material cost is much lower than that of color screens.
Extremely low power consumption: This is one of its core advantages, especially suitable for battery powered portable devices.
High reliability, long lifespan: simple structure, few components, and less prone to failure.
Good visibility under sunlight: Especially in reflective or semi reflective designs, ambient light can be utilized to see more clearly under strong light.
Mature technology and simple development: especially for segment code screens, the circuit and program are very simple.
Disadvantages:
Limited information representation: unable to display color information, not suitable for applications that require color differentiation.
The display content is monotonous: the visual expression is far inferior to color screens.
Relatively narrow viewing angle: Some types of black and white screens (such as TN screens) may experience a decrease in contrast or even color reversal when viewed from the side.
5.Typical application scenarios
Due to its unique advantages, black and white LCD screens are still an irreplaceable choice in many fields:
Industrial control and instrumentation: PLC touch screen, oscilloscope, multimeter, measuring equipment. Require stability, reliability, and long lifespan.
Medical equipment: blood glucose meter, blood pressure monitor, portable electrocardiogram machine. Require low power consumption and clear data.
Smart home control panel: thermostat, security system panel. The display information is simple and often requires continuous power on.
Consumer electronics products: calculators, electronic watches, early game consoles (such as Game Boy).
Portable terminal devices: supermarket barcode scanner, warehouse management PDA. Require durability and energy efficiency.
In car displays: auxiliary information screens on the dashboard and onboard computer screens of some cars.
summary
Black and white LCD screen is a display technology that focuses on functionality and practicality. It is not a "low-end version" of color screens, but the optimal solution for specific scenarios with extremely high cost, power consumption, and reliability requirements. When your application does not require fancy colors, but pursues long battery life, high stability, and low cost, a black and white LCD screen is an excellent choice.
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