Difference between revisions of "Chatter"

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(Working improved to distinguish chatter from bounce; I am not personally convinced though about the causes of chatter)
(Moved Contact Bounce to its own article (previously a redirect), and added Bad solder joint)
 
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'''Key chattering''' or simply '''chattering''', is an undesirable phenomenon that can affect certain types of keyboard switches. The effect of this problem is that a single press of the key results in multiple registered inputs. As an example, typing the word 'Deskthority' on a keyboard with a defective 'K' key suffering from chatter may yield the result 'Des'''kk'''thority'.
 
  
'''Contact bounce''' is a normal operating behaviour for metal contact switches: the movable switch contact will bounce repeatedly after the impact of closing, before settling into the closed position. Switch manufacturers specify the maximum bounce time for switch series, which is typically ≤ 5 ms for keyboard switches. The [[keyboard controller]] must implement de-bouncing: once a keypress has been detected, further changes been the closed and open states within the bounce threshold must be ignored.
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'''Key chatter''' or simply '''chatter''' is an undesirable phenomenon when a single key press results in multiple registered inputs.
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As an example, typing the word 'Deskthority' on a keyboard with a defective 'K' key suffering from chatter may yield the result 'Des'''kk'''thority'.  
  
Chattering occurs when the amount of switch bounce exceeds the threshold set by the keyboard controller, and multiple keystrokes are registered. This is a failure state of mechanical switches which can occur spontaneously in a previously known good switch.
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There are several reasons for key chatter listed below, with proposed solutions:
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==Bad solder joint==
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Mechanical key switches are soldered to [[printed circuit board]]s.
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A badly made solder joint could break and then intermittently not conduct electricity, with the symptom being key chatter.
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This is often the result of a "cold solder joint": If the solder pad and switch pin
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had not been sufficiently heated before solder was applied, the solder had not bonded with both of them properly.
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This cause of key chatter is more frequently observed on DIY-keyboards that people have soldered themselves, but has also been observed on mass-produced keyboards.
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The solution is to redo the soldering joint.
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==Defective switch==
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All key switches with [[Keystroke_sensing#Conductive|conductive contacts]] exhibit [[contact bounce]] for a very short amount of time, each time a key is pressed.
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This is normal, and is filtered out by a [[debouncing]] algorithm in the [[keyboard controller]].
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However, key chatter will occur if a switch has become defective in a way that makes it exhibit contact bounce for a longer duration than intended.
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Some makes of switches could have the occasional defective switch, and some types of switches are known to start chattering more easily than others,
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It has also happened that internal parts have been damaged when an enthusiast has [[:Category:Keyboard_modding|modified]] switches in some way, e.g. [[lubrication|lubricated]] switch innards.
  
 
There are suggested methods for remedying key chatter in defective switches, including the use of compressed air, although they are not universally recommended. Elitekeyboards.com strongly advises against this practice in the Support section of their website; however, they currently do not supply any information about what might happen to the keyboard if such actions are attempted, nor a preferred alternative.<ref>Elitekeyboards.com - [http://elitekeyboards.com/support.php?lang=en#5 Support page with key chattering/bouncing description]</ref>
 
There are suggested methods for remedying key chatter in defective switches, including the use of compressed air, although they are not universally recommended. Elitekeyboards.com strongly advises against this practice in the Support section of their website; however, they currently do not supply any information about what might happen to the keyboard if such actions are attempted, nor a preferred alternative.<ref>Elitekeyboards.com - [http://elitekeyboards.com/support.php?lang=en#5 Support page with key chattering/bouncing description]</ref>
  
==External Links==
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A sure solution is to replace the defective switch.
* http://en.wikipedia.org/wiki/Keyboard_technology#Debouncing
 
* http://en.wikipedia.org/wiki/Debounce#Contact_bounce
 
  
 
==References==
 
==References==

Latest revision as of 13:58, 21 April 2020

This article is a stub. You can help Deskthority by expanding it.

Key chatter or simply chatter is an undesirable phenomenon when a single key press results in multiple registered inputs. As an example, typing the word 'Deskthority' on a keyboard with a defective 'K' key suffering from chatter may yield the result 'Deskkthority'.

There are several reasons for key chatter listed below, with proposed solutions:

Bad solder joint

Mechanical key switches are soldered to printed circuit boards. A badly made solder joint could break and then intermittently not conduct electricity, with the symptom being key chatter.

This is often the result of a "cold solder joint": If the solder pad and switch pin had not been sufficiently heated before solder was applied, the solder had not bonded with both of them properly.

This cause of key chatter is more frequently observed on DIY-keyboards that people have soldered themselves, but has also been observed on mass-produced keyboards.

The solution is to redo the soldering joint.

Defective switch

All key switches with conductive contacts exhibit contact bounce for a very short amount of time, each time a key is pressed. This is normal, and is filtered out by a debouncing algorithm in the keyboard controller. However, key chatter will occur if a switch has become defective in a way that makes it exhibit contact bounce for a longer duration than intended.

Some makes of switches could have the occasional defective switch, and some types of switches are known to start chattering more easily than others,

It has also happened that internal parts have been damaged when an enthusiast has modified switches in some way, e.g. lubricated switch innards.

There are suggested methods for remedying key chatter in defective switches, including the use of compressed air, although they are not universally recommended. Elitekeyboards.com strongly advises against this practice in the Support section of their website; however, they currently do not supply any information about what might happen to the keyboard if such actions are attempted, nor a preferred alternative.[1]

A sure solution is to replace the defective switch.

References