Pixels emit their own light, and a grid of row and column lines selects which pixel is lit. No transistor sits at each pixel. This is the simpler and cheaper way to build an Organic Light Emitting Diode (OLED) panel. An active-matrix panel can respond and refresh faster. The grid-driven panel is the one used for small indicators and secondary screens.
How the Grid Addresses Each Pixel
Row lines run one way and column lines run the other. At every crossing, current can pass through the organic layers and light that pixel. A controller turns on one row at a time and sets the columns for the pixels that should glow in that row. The scan then moves to the next row. Nothing at the pixel stores that state between scans.
An active-matrix panel does the opposite. It puts a Thin-Film Transistor (TFT) at each pixel so the pixel can hold its level while other rows are addressed. The passive grid leaves that transistor out, which is why the stack is easier to build and costs less.
What Limits Response and Refresh
Only the selected row is driven during each step of the scan. Each pixel is lit for a fraction of the frame, and that fraction gets smaller as the panel adds rows. Response is slower, and refresh is lower, than on an active-matrix panel whose transistor holds every pixel while the scan moves on.
- Simpler drive: Shared row and column lines replace a switch at every pixel.
- Lower cost: Fewer layers and no per-pixel transistor make the panel cheaper to manufacture.
- Slower image change: Response and refresh fall behind an active-matrix panel that uses a thin-film transistor per pixel.
Passive-Matrix and Active-Matrix Panels
An Active-Matrix Organic Light-Emitting Diode (AMOLED) panel keeps the same self-lit organic layers and changes only the way each pixel is driven. The comparison below is the practical split between the two.
| Trait | Passive-Matrix Panel | Active-Matrix Panel |
| Pixel addressing | A grid of row and column lines, with no transistor at each pixel | A thin-film transistor at each pixel |
| Construction and cost | Simpler and cheaper | More complex and more costly |
| Response and refresh | Slower response and lower refresh | Faster response and higher refresh |
| Typical use | Small indicators and secondary screens | Panels that need fast updates and a higher refresh |