What the fraction counts
A scan rate of 1/16 means the driver lights one row out of every sixteen at any instant, then moves to the next. The cycle repeats fast enough that the eye sees a continuous image. The number describes a driving method, not a grade of quality.
It exists because of current. Every lamp on a module draws power, and lighting every row simultaneously would demand a driver board and a power supply far larger than any cabinet can hold. Scanning divides the load across time instead.
This is why the figure appears on nearly every module specification and on almost no quotation. Suppliers list it because it is part of the design; buyers rarely see it because it does not describe anything they can compare directly.
Why finer pitch means more rows scanned
Pixel density rises faster than people expect. Halving the pitch quadruples the number of lamps in the same area, because density scales with the square of the spacing. A 1.25 mm panel holds sixty-four times as many lamps per square metre as a 10 mm panel.
That lamp count is what forces the scan rate up. A 1.25 mm module cannot light all its rows at once for the same reason a 10 mm module can: the current would be unmanageable. So the driver divides the work across more steps.
The practical consequence is that a high scan rate on a fine pitch panel is normal engineering, not a compromise. A 1/32 scan on a 1.5 mm product is exactly what the lamp count requires.
The pattern across a real product range
Across a full indoor and outdoor range the relationship holds closely. Fine pitch indoor modules run between 1/26 and 1/32. A 1.25 mm panel typically scans 1/30, and 1.5625 mm and 2 mm products scan 1/32.
As the pitch opens, the fraction drops. Indoor 3.91 mm and 4 mm modules scan 1/16, 6 mm scans 1/16, and 7.62 mm and 10 mm modules fall to 1/8. Outdoor products are coarser still: 4 mm and 6 mm scan 1/8, 8 mm scans 1/4, and a 10 mm panel can scan as low as 1/2.
The exceptions are instructive. A 4.81 mm module scanning 1/13 sits slightly off the neat progression, which usually reflects a specific driver design. It is not a mistake on the sheet. When a figure breaks the pattern, it is worth one question.
What scanning costs you
Duty cycle falls as the scan rate rises. If a lamp is lit one thirty-second of the time, it produces less average light than the same lamp lit one eighth of the time. Designers recover the difference with higher drive current, brighter lamp bins and optical design, but the headroom is finite.
This is the real reason the figure matters to a buyer: it sets the ceiling on achievable brightness. Two panels quoting the same 1,000 candelas per square metre can reach it by very different routes, and the one running a higher scan rate is working closer to its limit.
Working near that limit has a cost over time. Driving lamps harder to compensate for a low duty cycle generates more heat and ages the lamp faster, which shows up as brightness loss and colour shift after a few thousand hours.
Where refresh rate fits
Refresh rate and scan rate are related but separate. Refresh rate is how many times per second the whole image is redrawn; scan rate is how the rows are grouped within each redraw. A high scan rate makes a high refresh rate harder to achieve, because the driver has more steps to complete in the same period.
This is why fine pitch products advertise refresh rates of 3,840 Hz and above. Reaching that figure while scanning thirty-two rows is a genuine engineering result, and it is the number that matters when cameras are involved.
For a screen that will only ever be watched by eye, refresh rate above roughly 1,920 Hz adds nothing visible. Spend the question on brightness uniformity and calibration instead.
How to use it when comparing quotes
Do not compare scan rates across different pitches. A 1/32 panel is not worse than a 1/8 panel; it is a panel with sixteen times the lamp density. The comparison only means something between two products at the same pitch.
Between two quotes at the same pitch, the lower scan rate is generally the stronger design, because it implies a higher duty cycle and more brightness headroom. Ask what brightness each achieves and at what drive level, and let those figures decide.
If a supplier quotes a scan rate but no brightness, or a brightness but no scan rate, ask for both. One without the other tells you very little about how the panel will actually perform in your room.
Four questions worth asking
What brightness does the panel hold at its rated drive level, and what is the drive level? A brightness figure without a current figure is easy to overstate.
What refresh rate is specified, and is it measured or calculated? Ask whether the figure holds at full white. Low grey levels flatter the number.
How is brightness maintained over time? Look for a stated calibration approach and a figure for brightness loss after a defined number of hours.
What happens at the dimmest setting you will actually use? Meeting rooms and control rooms run screens far below maximum output, and uniformity at that level matters more than peak brightness.
A number that misled the buyer
A buyer picked a panel because it advertised a high scan rate, then found it dimmer than a lower-scan rival. Comparing across different pitches had hidden the trade-off.
Same pitch, fair comparison
Two quotes at the same 2.5 mm pitch showed different scan rates. Compared correctly, the higher scan gave cleaner motion at the cost of some brightness, a real trade the buyer could weigh.
Steps for a project: scan rate
- Read the fraction as a driving method A scan rate like 1/8 or 1/32 describes how the driver divides its load across rows. It is a method, not a quality grade, so do not rank panels by the number alone.
- Compare only at the same pitch Scan climbs with pixel density because finer pitch packs far more lamps. Compare scan rates only between panels of the same pitch, or the number misleads.
- Judge by measured results Let measured brightness, refresh and uniformity decide the panel, with scan rate as context. A high scan that dims the wall is no win.
- Ask the right questions When a quote lists only brightness, ask for scan method, refresh and how they behave together. The four questions worth asking cover the whole driving chain.
Common misreads of scan rate
“A 1/32 scan is worse than 1/8.” — At the same pitch, a higher scan usually means finer driving and cleaner motion, often at some brightness cost. Across different pitches the comparison is not valid.
“Scan rate is the main quality number.” — It is one link in the driving chain. Brightness, refresh and uniformity, measured together, decide quality; scan rate is context, not the grade.
A note for the supplier: scan rate
Scan rate describes how a driver divides its load across rows, and it climbs with pixel density because finer pitch means far more lamps. Compare it only between panels of the same pitch, and let measured brightness, refresh rate and behaviour at low output decide between two quotes.