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intersection. The keyboard controller scans the columns. If a key has been pressed, the controller scans the rows, determines the row-column combination at which a key has been pressed, and generates the code corresponding to that key. This process occurs so quickly that the user is unaware of any delay.
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There are at least two limitations with this system. The first is that it provides only a crude binary on/off signal for each key. Better electronic musical keyboards employ two sets of switches for each key that are slightly offset. By determining the timing between the activation of the first and
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or a computer keyboard might require 62 wires to connect (one for each key, and a ground)—an awkwardly thick bundle of wiring. With a matrix circuit, any of 61 keys can be determined with only 16 wires. This is drawn schematically as a matrix of 8 columns and 8 rows of wires, with a switch at every
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Monophonic instruments and most low-cost computer keyboards reduce costs by leaving out most or all of those diodes. To avoid "phantom keys", the keyboard controller in modern low-cost computer keyboards will ignore further key presses once two keys (other than
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synthesizer shows the various internal components. The switches for each key are connected to the microprocessor chip using a matrix circuit. Even though the SY77 has 61 keys, only two small ribbon cables of wiring comes from the keyboard matrix.
43:. For example, 16 wires arranged in 8 rows and 8 columns can connect 64 keys—sufficient for a full five octaves of range (61 notes). By scanning these crossings, a keyboard controller can determine which keys are currently pressed.
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second switches, the velocity of a key press can be determined—greatly improving the performance dynamic of a keyboard.
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In addition to musical keyboards and regular computer keyboards, the matrix circuit approach is also used in
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prevents unwanted notes ("phantom keys") from being triggered, or intended notes from being masked (
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in which the key switches are connected by a grid of wires, similar to a
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The second is that instruments with a matrix circuit can only play in a
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would be used to scan the keyboard as well, providing further savings.
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222:"Microchip AN529: Multiplexing LED Drive and a 4x4 Keypad Sampling"
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fashion without the addition of a diode for each key crossing. The
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51:Without a matrix circuit, a 61-key keyboard for a
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96:) have been pressed, which is known as
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31:is a design used in most electronic
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204:"Understanding the Switch Matrix"
190:Jeff Tyson and Tracy V. Wilson.
178:Jim Cairns, "Keyboard Encoders"
114:Often in pocket calculators the
107:(such as for calculators) and
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192:"How Computer Keyboards Work"
116:multiplexed digit drive lines
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240:Synthesizer electronics
98:key jamming or ghosting
29:keyboard matrix circuit
18:Keyboard matrix (music)
167:"Keyboard Matrix Help"
143:Polyphony (instrument)
86:"phantom key blocking"
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245:Computer keyboards
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37:computer keyboards
33:musical keyboards
16:(Redirected from
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210:on 2017-06-11.
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138:Diode matrix
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65:Yamaha SY77
47:Description
234:Categories
149:References
111:machines.
78:monophonic
250:Switches
122:See also
224:. 1997.
169:. 2000.
109:pinball
105:keypads
82:diode
35:and
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27:A
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