Key switch scanning and encoding system

Claim 2

A switch scanning and encoding system in an electronic musical instrument, said instrument including a plurality of keycontrolled switches arranged in a matrix of M columns and N rows, each column of switches being separately enableable, the switches in each row being connected to N corresponding row output lines, and musical tone generation circuitry responsive to said encoded signals, the improvement comprising: encoding circuitry, scanning means for sequentially gating each of said N output lines to said encoding circuitry, said encoding circuitry providing a coded signal identifying the gated line if the switch in the enabled matrix column connected to that gated line is closed and providing no coded signal if that switch is open, first skip means for causing said scanning means to gate the next output line to said encoding circuitry if no coded signal is provided, and second skip means, operative if a coded signal is provided from said encoding circuitry, for causing said scanning means to dwell for a period of time sufficient to permit utilization of said coded signal.

Claim 3

A switch scanning and encoding system according to claim 1 wherein said first skip means has timing circuitry for causing the scanning means to gate on the next output line in a time period substantially less than the dwell time of said second skip means.

Claim 4

An electronic keyboard musical instrument incorporating a switch scanning and encoding system, said instrument having keyboard actuated note selection switches and other switches controlling characteristics of the musical sounds generated by said musical instrument, said keyboard and other switches being arranged in a switch matrix of M columns and N rows, the switches in each row being connected to a respective one of N common output lines, and musical sound generating circuitry, said system comprising; group enabling means for enabling each of said M columns of switches one column at a time, so that output signals are provided only on those output lines connected to actuated switches in the enabled column, a code matrix having N inputs, N line select gates each gating one of said output lines to a respective input of said code matrix, said code matrix providing a coded output only if the switch in the enabled column and connected to the line gated to said code matrix is actuated, N-stage recirculating register means for sequentially enabling said line select gates, and first shift means responsive to the output of said code matrix for causing said register means to enable the next line select gate upon detection of a no-code condition from said code matrix, and second shift means, operative in response to detection of a coded output from said code matrix, for causing said register means to eNable the next line select gate after a period of time sufficient to permit utilization of said coded output, and interconnection lines for supplying said coded output to said sound generating circuitry for utilization thereby.

Claim 5

An electronic keyboard musical instrument incorporating a switch scanning and encoding system, said instrument having keyboard actuated note selection switches and other switches controlling characteristics of the musical sounds generated by said musical instrument, said keyboard and other switches being arranged in a switch matrix of M columns and N rows, the switches in each row being connected to a respective one of N common output lines, and musical sound generating circuitry, said system comprising; group enabling means for enabling each of said M columns of switches one column at a time, so that output signals are provided only on those output lines connected to actuated switches in the enabled column, a code matrix having N inputs, N line select gates each gating one of said output lines to a respective input of said code matrix, said code matrix providing a coded output only if the switch in the enabled column and connected to the line gated to said code matrix is actuated, N-stage recirculating register means for sequentially enabling said line select gates, and first shift means responsive to the output of said code matrix for causing said register means to enable the next line select gate upon detection of a no-code condition from said code matrix, and second shift means, operative in response to detection of a coded output from said code matrix, for causing said register means to eNable the next line select gate after a period of time sufficient to permit utilization of said coded output, and interconnection lines for supplying said coded output to said sound generating circuitry for utilization thereby.

Claim 6

An electronic musical instrument according to claim 3 wherein said generating circuitry includes a memory storing frequency numbers determinative of the fundamental frequency of the generated musical sound, the coded outputs resultant from actuation of said note selection switches corresponding to addresses of said frequency number memory.