Back to results
US 4,548,119 AGranted
Digital filter for an electronic musical instrument
AssigneeNippon Gakki Seizo Kabushiki Kaisha
InventorsMasatada Wachi, Mitsumi Katoh
Life of this patent
Estimating the term…
Abstract
An electronic musical instrument comprises a keyboard, a tone generator and a digital filter. The tone generator bit-serially generates a musical tone signal corresponding to a depressed key on the keyboard. The digital filter bit-serially performs a digital filtering operation of the musical tone signal in accordance with the predetermined amplitude-frequency characteristic. A musical tone is produced based on an output of the digital filter, whereby the characteristic is imparted to the musical tone. This bit-serial processing in the digital filter makes not only the circuit construction of the digital filter itself but also that of the electronic musical instrument incorporating this digital filter smaller and simpler.
Claims18
A digital filter system in an electronic musical instrument comprising:
- tone signal supply means for timewisely serially supplying digital tone signals consisting of successive musical tone sample point amplitudes each represented by a plural bit digital value, each such value being delivered bit serially on a single line;
- filter coefficient supply means for timewisely bit serially supplying plural bit filter coefficients which establish a tone color;
- and
- calculation means for implementing a predetermined filter operation by performing mathematical operations in bit-serial fashion on said bit serially delivered sample point amplitudes supplied by said tone signal supply means and the bit serially supplied filter coefficients from said filter coefficient supply means to produce bit serially outputted tone signals which are filter-controlled in response to said filter coefficients.
1 more element
An electronic musical instrument comprising:
- keyboard means having a plurality of keys;
- tone signal generating means for bit-serially generating in real time a digital tone signal corresponding to a depressed key among said keys, said digital tone signal being in the form of successive sample point values each of plural bits delivered bit-serially on a single line;
- tone color setting means for setting a tone color of a tone to be produced;
- filter coefficient generating means for bit-serially generating filter coefficients corresponding to said setted tone color, each of said filter coefficients being in the form of bit-serial;
- digital filtering means connected to said tone signal generator and said filter coefficient means for bit-serially performing in real time a digital filtering operation of said digital tone signal in accordance with said filter coefficients;
- and
- sound means for producing a tone corresponding to said filtered tone signal, said setted tone color being imparted to said tone.
4 more elements
An electronic musical instrument comprising:
- keyboard means having a plurality of keys;
- tone signal generating means having a plurality of tone production channels for bit-serially delivered on a single line digital tone signals assigned to said channels and corresponding to a depressed key or keys among said keys in time-division-multiplexed mode, each of said digital tone signals being in bit serial form and being delivered at a rate corresponding to the frequency of the tone to be produced therefrom;
- tone color setting means for setting tone colors of tones to be produced;
- filter coefficient generating means for bit-serially generating sets of filter coefficients corresponding to said setted tone colors in time-division-multiplexed mode, each of said filter coefficients being in bit-serial form;
- digital filtering means connected to said tone signal generating means and said filter coefficient means for bit-serially performing a digital filtering operation on said delivered digital tone signals in accordance with said sets of filter coefficients;
- and
- sound means for producing tones corresponding to said filtered digital tone signals, said setted tone colors being imparted to said tones respectively.
4 more elements
An electronic musical instrument comprising:
- keyboard means having a plurality of keys;
- tone signal generating means connected to said keyboard means for generating a musical tone signal having a pitch designated by a depressed one among said keys, said musical tone signal consisting of successive sample point amplitudes each being represented by a plural bit digital code supplied bit-serially on a single line;
- filter coefficient supply means for bit-serially supplying a filter coefficient represented by a plural bit digital code;
- digital filtering means for bit-serially receiving said musical tone signal and said filter coefficient, for filtering said musical tone signal in accordance with said filter coefficient on a bit-by-bit basis in time synchronism with the bit-serial supply of said musical tone signal, and for bit-serially outputting a filtered musical tone signal represented by a plural bit digital code;
- and
- sound means for producing a musical tone corresponding to said filtered musical tone signal, said sample point amplitude musical tone signals being supplied and filtered by said digital filtering means continually in real time as said musical tone is being produced by said sound means.
3 more elements
In an electronic musical instrument, a fixed formant digital filter operative in real time to digitally filter successive musical tone sample point amplitudes supplied sequentially in bit serial digital format, comprising:
- a plurality of serially connected filter units each adapted for implementing a filter function by bit serially performing mathematical operations on said tone waveshape sample point amplitudes as they are serially supplied in real time to the input of said serially connected filter units, said sample point amplitude values being modified by said mathematical operations during serial propagation through said filter units,
- means for supplying successive bits of a set of multibit filter coefficients in sequence to each of said serially connected filter units in synchronism with the propagation therethrough of said sample point amplitude values,
- said serially connected filter units thereby performing said mathematical operations serially on the amplitude sample point values being propagated therethrough in accordance with said serially supplied filter coefficients so as to implement said fixed formant digital filter, the bit serial data emergent from the last of said serially connected filter units constituting successive sample point amplitude values of a musical tone to which fixed formant characteristics have been imparted by said digital filter.
Dependencies are inferred from the claim text.