Scan rate refers to the speed at which a keyboard internally reads data, while polling rate refers to the speed at which it reports that data to the computer. Although they are linked sequentially in the signal chain, their functions are entirely different. The scan rate determines whether the keyboard can ”perceive” the slightest movement of a key, whereas the polling rate determines how frequently that data is transmitted to the computer.
I. Core Definitions: Internal Processing vs. External Transmission
Scan Rate (or Sampling Rate): The frequency at which the keyboard’s microcontroller reads data from Hall-effect sensors (or optical/mechanical contacts). For magnetic-switch keyboards, the scan rate determines how many times per second the controller ”samples” the magnetic field position of the switch stem. A higher scan rate allows for finer perception of key travel changes and greater precision in ”Rapid Trigger” calculations.
Polling Rate: The frequency at which the keyboard sends data to the computer via USB or a wireless connection, measured in Hertz (Hz). A rate of 1000Hz means data is sent every 1ms, while 8000Hz means it is sent every 0.125ms.
II. Signal Chain: What Determines the ”Actual Data”?
Key data flow within the keyboard follows a fixed sequence:
Sensor detection → Scan rate sampling → Microcontroller processing (RT algorithms/debouncing) → Polling rate packaging and reporting → Computer reception
The scan rate represents the front end of this chain, while the polling rate represents the back end.
There is a commonly overlooked technical pitfall here known as the ”Polling Rate Paradox.” If a keyboard has a scan rate of only 1000Hz (sampling once every 1ms) but a rated polling rate of 8000Hz (reporting every 0.125ms), it captures only one actual position data point within that 1ms window yet transmits it eight times. Consequently, the subsequent seven data packets received by the computer contain identical, outdated information. This results in a ”stepped” input curve; while the connection is fast, the data itself remains unchanged.
To truly leverage the advantages of an 8000Hz polling rate, the scan rate must keep pace accordingly. This is why mid-to-high-end magnetic switch keyboards emphasize the combination of a high scanning rate and a high polling rate.
III. Industry Data: How the Two Are Paired
Specifications of current market products confirm this relationship:
– ATK EDGE 60/63HE: 256K scanning rate + 8K polling rate; minimum latency of 0.08ms.
– AULA AG63 Standard Edition: 256kHz full-key scanning rate + 8kHz polling rate; PRO Edition upgraded to a 32kHz keyboard scanning rate.
– MCHOSE ACE60 PRO: 32K scanning rate + 8K polling rate; ACE60 Standard Edition features a 16K scanning rate + 1K polling rate.
– Akko TAC75 HE: 16K general scanning rate; the manufacturer explicitly states it ”truly unlocks the performance potential of an 8K polling rate.”
IV. Two Ways of Specifying Scanning Rate: Full-Key vs. Single-Key
There is a common point of confusion when manufacturers specify scanning rates: ”full-key scanning rate” and ”single-key scanning rate” are simply two ways of calculating the same physical metric.
”Full-key scanning rate” refers to the frequency at which the microcontroller completes a full scan of all keys. For example, a ”256K full-key scanning rate” means the microcontroller performs a complete scan of all keys 256,000 times per second. If one works backward from the number of keys to determine the sampling interval for an individual key—using a 100-key keyboard as an example—the number of times a single key is scanned per second is 256,000 × 100 = 25,600,000; this is the source of the ”single-key scanning rate” figure. Both terms describe the same process; they simply use different calculation methods.
V. Why Do Magnetic Switches Require Higher Scanning Rates Than Mechanical Switches?
Mechanical switches output simple ”on” or ”off” signals; the microcontroller only needs to determine whether the circuit is conducting during the scan. Magnetic switches output continuous analog voltage values; the main controller must perform an ADC conversion during every scan cycle to translate the analog voltage into a digitized travel position.
This means that every ”scan” of a magnetic switch entails a complete process of sampling, quantization, and calculation, placing a significantly higher computational load on the main controller compared to mechanical switches. While a higher scan rate increases the burden on the controller, it yields the benefits of improved Rapid Trigger (RT) precision and greater actuation consistency.
