I. Technical Principle: Completely Different Display Logic

The fundamental difference between electronic paper (Epaper) and reflective LCDs stems from the different underlying display technology logic, which directly determines their core characteristics.

1. Epaper: A Paper-Like Display Based on the "Electrophoretic Effect"

Mainstream Epaper utilizes electrophoretic display (EPD) technology. Its core structure consists of microcapsules containing tiny charged particles (usually black and white) encapsulated in a transparent substrate. When an external electric field is applied, the charged particles move in the direction of the field:

When white particles move to the surface of the substrate, they reflect the light around them, making them appear white.

Black particles look black because they absorb light when they move to the surface.

One of its most important features is something called bistability. This means that once the particles are in position, the displayed content stays visible even when the electric field is switched off. This means that you don't need a constant power supply. This makes the display look like traditional paper, but without the backlight or flicker.

2. Reflective LCD: Light Control Based on "Liquid Crystal Deflection"

Reflective LCD is essentially a branch of LCD technology. Its core structure consists of a liquid crystal layer, a polarizer, and a reflective layer (which replaces the backlight module of traditional LCDs). Its operating principle is as follows:

When there is no electricity, the liquid crystal molecules line up in a certain way. This allows light from the environment to pass through the polariser and be reflected by the reflective layer. This results in a white display.

When voltage is applied, however, the molecules deflect, changing the light's polarisation direction. This stops light from passing through the polariser, which causes it to be absorbed and results in a black display (or a colour display through a colour filter).

Unlike e-paper, reflective LCDs have no self-light (reflecting ambient light) but require continuous power for liquid crystal alignment; power failures erase displayed content.

II. Core Features: Display Quality & Power Consumption Differences

The differences in their technical principles translate into significant differences in key features such as display quality, power consumption, and response speed. A detailed comparison is provided below:

Feature Dimension	Epaper LCD	Reflective LCD
Display effect	1. High contrast (close to paper printing) with no glare; 2. Nearly 180° viewing angle with no color difference; 3. Mainly black and white/grayscale (color e-paper is expensive and has a narrow color gamut).	1. Low contrast (significantly affected by ambient light intensity) and prone to glare under strong light; 2. Viewing angle is approximately 120°-160°, and color cast is prone to occur at wide viewing angles; 3. Supports full-color display with a wider color gamut.
Power consumption performance	Extremely low power consumption: Power is consumed only when refreshing content, and power consumption approaches 0 when static display is in effect (battery life can reach weeks/months).	Low to medium power consumption: Requires continuous power supply to maintain display (even for static content), and consumes about 1/5-1/3 of traditional LCDs, but much higher than e-paper.
Response speed	Slow (typical refresh time 0.5-2 seconds), suitable for static content (such as text and pictures), dynamic images are prone to ghosting.	Fast (typical response time 10-50 milliseconds), capable of supporting simple dynamic content (such as scrolling text and low frame rate animations).
Environmental adaptability	The display is clear under strong light (high reflectivity), and requires external light source assistance (such as front light) in low light conditions.	It is easy to reflect light under strong light, which reduces the display effect; front light is required in low-light environment (power consumption is further increased).
Flexible characteristics	Supports flexible substrates (such as plastic substrates) to achieve bending and folding displays (such as flexible electronic paper).	Relying on glass substrates, flexibility is difficult, and most displays are rigid.

III. Application Scenario: Differentiated Selection Based on Features

Due to differences in core characteristics, e-paper and reflective LCDs exhibit distinct divisions of labor in their application areas, each catering to different scenarios.

1. Electronic Paper (Epaper): Prioritizes static and low-power requirements

Reading devices: E-book readers like the Kindle and e-paper notebooks. These devices have a display quality similar to paper and use low power to meet the needs of long-term reading;

Static information displays: Supermarket price tags, bus stop signs, hospital call screens, and electronic posters, which require frequent refreshes and can be clearly displayed even in strong outdoor sunlight;

Portable devices: E-paper watches and smart bracelets (with battery life of several months), and display panels for some industrial equipment (requires low power consumption and anti-glare).

2. Reflective LCD: Prioritizes color and dynamic requirements

Consumer electronics: Some smartwatches (such as the reflective screen of the early Apple Watch) and portable navigation systems require color displays and low power consumption;

Outdoor devices: Shared bicycle lock displays and outdoor thermometers, which need to be visible in natural light and support simple dynamic information (such as jumping numbers);

Industrial and automotive: Industrial control panels and vehicle instrument clusters (some low-end models), which require fast response to operating commands and are lower in cost than e-paper.

IV. Summary: Selection Logic and Future Trends

E-paper and reflective LCDs are not "substitutes," but rather "complementary choices" based on scenario needs:

For applications requiring long-duration static display, low power consumption, and a paper-like experience (such as reading and price tags), e-paper is the optimal solution, and color e-paper technology (such as E Ink Kaleido) is gradually breaking through color gamut limitations.

Reflective LCDs offer greater cost advantages and remain irreplaceable in miniaturised devices requiring colour display, fast response speeds and low-to-medium power consumption, such as smart wearables and outdoor devices.

As flexible e-paper and low-power reflective LCD technologies advance in the future, they will penetrate more niche applications. Examples include flexible e-paper posters and in-vehicle flexible reflective displays. These technologies will provide users with more tailored display solutions.