Definition
A Memory LCD (Sharp Memory LCD or Memory-in-Pixel display) is a reflective LCD where each pixel contains its own memory cell, eliminating the need for continuous refresh signals. The display holds its image without continuous power — consuming energy only during pixel updates. Memory LCD combines the low power of e-paper with the fast refresh capability of standard LCD.
Memory LCD vs TFT LCD vs E-Paper
| Property | Memory LCD | TFT LCD | E-Paper |
|---|---|---|---|
| Power (static image) | Near zero | High (backlight) | Zero |
| Refresh rate | Up to 60fps | Up to 240fps | 0.5–2fps |
| Backlight required | Optional (reflective) | Always | No |
| Sunlight readability | Excellent | Needs enhancement | Excellent |
| Interface | SPI (simple) | Parallel/MIPI/LVDS | SPI/I2C |
Key Advantages
- Ultra-low power: ideal for always-on battery displays
- No external frame buffer needed — reduces system RAM and CPU load
- Fast enough for live data, waveforms, and menu navigation
- Sunlight readable in reflective mode — no backlight needed outdoors
- Simple SPI interface — easy integration with microcontrollers
- Wide operating temperature: -20°C to +70°C standard
Applications
- Smartwatches and fitness trackers (always-on watch face)
- Medical patient monitors and handheld diagnostics
- Industrial meters, sensors, and data loggers
- Smart thermostats and building control panels
- Military wearables and dismounted soldier electronics
- IoT gateways and edge devices needing a status display
Frequently Asked Questions
What is the power consumption of a Memory LCD?
A 1.28″ Memory LCD in always-on static display mode consumes approximately 15–30 µW — orders of magnitude less than a TFT LCD with backlight.
Memory LCD vs e-paper — what is the difference?
Memory LCD refreshes at up to 60fps, making it suitable for live data and animations. E-paper refreshes in 500ms+ and is best for static or slowly-changing content. Memory LCD also requires a small amount of power to maintain the image; e-paper requires none.