Electronic musical instruments

Abstract

In an electronic musical instrument of digital processing type, key codes are stored in a memory channel by channel for respective tone productions. The stored key codes are utilized for determining pitches of respective tones to be produced. Upon depression of new keys, the formerly stored key codes are automatically added or subtracted channel by channel with the value for a certain note step toward the new key codes at a certain clock rate defining a glissando speed. Thus automatic glissando performances are easily realized.

What is claimed is: 
     
       1. An electronic musical instrument comprising key coder means for delivering key code signals identifying depressed keys, said key code signals having values which only identify depressed keys and which are not proportional to tone frequencies represented by said depressed keys, key code memory means for storing said key code signals, comparator means connected to said key coder means and to said key code memory means for comparing a first key code received from said key code memory means with a second key code received from said key coder means, calculation means responsive to the result of comparison in said comparator means for adding to or subtracting from the content of said key code memory means a predetermined value defining a semitone step repetitively at a predetermined clock rate to change said first key code in said key code memory means by successive semitone steps one after another to the next key code until said first key code in said key code memory means becomes equal to said second key code, and tone forming means connected to said key code memory means for forming a musical tone having a pitch determined by said key code in said key code memory means. 
     
     
       2. An electronic musical instrument according to claim 1 which further comprises a variable frequency oscillator for producing a signal that determines said clock rate. 
     
     
       3. An electronic musical instrument comprising key coder means for delivering key code signals identifying depressed keys, said key code signals having values which only identify depressed keys and which are not proportional to tone frequencies represented by said depressed keys, key code memory means for storing said key code signals, comparator means connected to said key coder means and to said key code memory means for comparing a first key code received from said key code memory means with a second key code received from said key coder means, calculation means responsive to the result of comparison in said comparator means for adding to or subtracting from the content of said key code memory means a predetermined value defining a semitone step repetitively at a predetermined clock rate to change said first key code in said key code memory means until said first key code becomes equal to said second key code, tone forming means connected to said key code memory means for forming a musical tone having a pitch determined by said key code in said key code memory means, wherein said key coder means produces said key code signals on a time division basis, and said key code memory means comprises a plurality of memory stages for storing said key code signals on the time division basis. 
     
     
       4. An electronic musical instrument according to claim 3 wherein said key coder means comprises memory means for storing said key code signals at memory stages corresponding to time division channels. 
     
     
       5. An electronic musical instrument according to claim 4 wherein said key coder means further comprises first means for representing a time division channel to be secured, and second means responsive to the output of said first means for determining a stage of said memory means utilized to store said key code signal thereby storing key code signals at said stage and not yet secured stages. 
     
     
       6. An electronic musical instrument comprising key coder means for delivering key code signals identifying depressed keys, said key code signals having values which only identify depressed keys and which are not proportional to tone frequencies represented by said depressed keys, key code memory means for storing said key code signals, comparator means connected to said key coder means and to said key code memory means for comparing a first key code received from said key code memory means with a second key code received from said key coder means, calculation means responsive to the result of comparison in said comparator means for adding to or subtracting from the content of said key code memory means a predetermined value defining a semitone step repetitively at a predetermined clock rate to change said first key code in said key code memory means until said first key code becomes equal to said second key code, and tone forming means connected to said key code memory means for forming a musical tone having a pitch determined by said key code in said key code memory means, and wherein said tone forming means includes first means for producing a tone pitch voltage corresponding to the output of said key code memory means, a capacitor for storing said voltage, and a voltage controlled type variable frequency oscillator for generating an oscillation having a frequency determined by the voltage stored in said capacitor. 
     
     
       7. An electronic musical instrument according to claim 6 which further comprises second means for varying the charging time constant of said capacitor. 
     
     
       8. An electronic musical instrument according to claim 7 which further comprises a variable frequency oscillator for producing a signal that determines the clock rate for said calculation means. 
     
     
       9. An electronic musical instrument comprising key coder means for delivering key code signals identifying depressed keys, key code memory means for storing said key code signals, comparator means connected to said key coder means and to said key code memory means for comparing a first key code received from said key code memory means with a second key code received from said key coder means, calculation means responsive to the result of comparison in said comparator means for adding to or subtracting from the content of said key code memory means a predetermined value defining a semitone step repetitively at a predetermined clock rate to change said first key code in said key code memory means until said first key code becomes equal to said second key code, tone forming means connected to said key code memory means for forming a musical tone having a pitch determined by said key code in said key code memory means, first means for producing a tone pitch voltage corresponding to the output of said key code memory means, a capacitor for storing said voltage, a voltage controlled type variable frequency oscillator for generating an oscillation having a frequency determined by the voltage stored in said capacitor, second means for varying the charging time constant of said capacitor, a second variable frequency oscillator for producing a signal that determines the clock rate for said calculation means, and third means for controlling the oscillation frequency of said second variable frequency oscillator, said second means and said third means being so interrelated that said charging time constant becomes shorter as said oscillation frequency of said second variable frequency oscillator becomes higher, and vice versa. 
     
     
       10. An electronic musical instrument comprising key coder means for delivering key code signals identifying depressed keys, key code memory means for storing said key code signals, comparator means connected to said key coder means and to said key code memory means for comparing a first key code received from said key code memory means with a second key code received from said key coder means, calculation means responsive to the result of comparison in said comparator means for adding to or subtracting from the content of said key code memory means a predetermined value defining a semitone step repetitively at a predetermined clock rate to change said first key code in said key code memory means until said first key code becomes equal to said second key code, tone forming means connected to said key code memory means for forming a musical tone having a pitch determined by said key code in said key code memory means, first means for producing a tone pitch voltage corresponding to the output of said key code memory means, a capacitor for storing said voltage, a voltage controlled type variable frequency oscillator for generating an oscillation having a freqency determined by the voltage stored in said capacitor, means for generating a signal representing a released key state, a first gate means connected between said capacitor and said tone pitch voltage generating means, a second gate means for controlling said first gate means by said signal generated by said signal generating means, and a manual switch for controlling said second gate means. 
     
     
       11. An electronic musical instrument comprising key coder means for delivering key code signals identifying depressed keys, key code memory means for storing said key code signals, comparator means connected to said key coder means and to said key code memory means for comparing a first key code received from said key code memory means with a second key code received from said key coder means, calculation means responsive to the result of comparison in said comparator means for adding to or subtracting from the content of said key code memory means a predetermined value defining a semitone step repetitively at a predetermined clock rate to change said first key code in said key code memory means until said first key code becomes equal to said second key code, tone forming means connected to said key code memory means and forming a musical tone having a pitch determined by said key code in said key code memory means, a variable frequency oscillator for producing a signal that determines said clock rate, a variable voltage source which controls the oscillation frequency of said variable frequency oscillator, a comparitor which compares the voltage of said variable voltage source with a predetermined reference voltage, and means responsive to the output of said comparitor for rendering inoperative said calculation means thereby directly applying the newly supplied key code signal to said key code memory means. 
     
     
       12. An electronic musical instrument comprising key coder means for delivering key code signals identifying depressed keys, key code memory means for storing said key code signals, comparator means connected to said key coder means and to said key code memory means for comparing a first key code received from said key code memory means with a second key code received from said key coder means, calculation means responsive to the result of comparison in said comparator means for adding to or subtracting from the content of said key code memory means a predetermined value defining a semitone step repetitively at a predetermined clock rate to change said first key code in said key code memory means until said first key code becomes equal to said second key code, means connected to said key code memory means and forming a musical tone having a pitch determined by said key code in said key code memory means, said key coder means producing said key code signals on a time division basis and said key code memory means further comprising a plurality of memory stages for storing said key code signals on the time division basis, said key coder means further comprising memory means for storing said key code signals at memory stages corresponding to time division channels, means for generating a tone pitch voltage corresponding to the output of said key code memory means, a plurality of capacitors corresponding to a plurality of time division channels and adapted to store said tone pitch voltage, a plurality of variable frequency oscillators for generating oscillation frequencies respectively corresponding to the voltages of said capacitors, and switch means for assigning said tone pitch voltage to said capacitors on the time division basis.