Abstract:
An electronic musical instrument whose operation is similar to a harmonica, and which can be played easily by anyone familiar with a harmonica. The instrument measures positive or negative pressure at the mouthpiece, with a MEMS (Micro-electro-mechanical system) pressure sensor, which produces an electronic signal, which is then converted to pre-sampled sounds of a variety of instruments via an on-board synthesizer, and is capable of sending MIDI (Musical Instrument Digital Interface) signals to control other electronic musical instruments or devices.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an electronic musical instrument capable of reproducing much of the feel of a harmonica, while providing the capacity to reproduce the sound of most any other instrument. 
     2. Description of Related Art 
     Prior technologies have considered the possibility of reproducing sound by means of measuring movement of reeds in a harmonica via optical or magnetic means. Antaki, U.S. Pat. No. 6,326,532. 
     Other instruments have utilized flow sensors, requiring a mechanism within the air stream. Wheaton, U.S. Pat. No. 5,245,130; Schille, U.S. Pat. No. 4,984,490. 
     Pressure-transducers have been considered in the past as components in a wind instrument, to measure vibrations within the air column. Criglar, et al., U.S. Pat. No. 4,119,007. 
     In the past, mouth-pieces have been designed with separate passages for blow and draw. Nagura, U.S. Pat. No. 4,252,045. 
     Prior attempts at creating an electronic harmonica have resulted in a device requiring external sound synthesis via wire or radio emissions. 
     Based on the foregoing, there is a need in the art for a device that reproduces sound without reeds, airflow through a sensor, or moving parts in the air stream. Further, there is a need for a device for reproducing sound that uses an ambient-referenced pressure sensor, eliminating the need for separate passages and sensors, making the mouth-piece that is simple in design. Furthermore, there is a need for a device that is capable of triggering and controlling the dynamics of a synthesized sound. Finally, there is a need in the art for an electronic musical instrument that synthesizes sound within the body of the instrument, rather than requiring external sound synthesis. 
     SUMMARY OF THE INVENTION 
     In an embodiment of the present invention, a musical instrument has micro-electro-mechanical system (MEMS) pressure sensors that translate an air pressure to an electrical voltage; a mouthpiece, with air passages and vent holes, to channel air to the pressure sensors; a digital to analog converter to measure an electrical output of the pressure sensors; a user interface that allows a user to control the instrument; a microprocessor, that reads an electronic signal from the pressure sensors; a software program, that directs the microprocessor to perform a specific operation; an on-board sound-synthesis system that converts the electronic signal to sounds of a variety of instruments; a battery that provides power to the instrument; a charging system that charges the battery; and a drip tray beneath the mouthpiece that retains moisture escaping from the vent holes. 
     In an embodiment, the mouthpiece is removable and replaceable, and is configurable with air passages varying in size, shape, number, and spacing therebetween. 
     In an embodiment, the instrument has a body, wherein a portion of the body is recessed on a front edge, forming a cavity that has a lower surface, wherein the cavity receives the mouthpiece; a groove in the exterior bottom surface of the mouthpiece, in which the groove extends the length of the mouthpiece; and a tongue extending upward from the lower surface of the cavity. The tongue and groove mate with one another when an end of the mouthpiece is inserted into, or removed from, an open end of the cavity. 
     In an embodiment, the musical instrument has a mating component behind the mouthpiece to provide a seal to the mouthpiece and an interface to the pressure sensors. There is no airflow through the pressure sensors. 
     In an embodiment, the musical instrument has a percussive mode, a non-percussive mode, and a third mode. In the percussive mode, the instrument plays a set of notes at a pre-determined volume of attack. In the non-percussive mode, the instrument plays each note based on an instantaneous air pressure at the mouthpiece. In the third mode, the instrument blends the percussive and non-percussive modes to play the notes, in which the notes have a pre-set trigger level. 
     In an embodiment, the musical instrument has a USB port that allows a user to charge the battery, and upload and download information. 
     In an embodiment, the musical instrument has on-board memory, allowing a user to save instrument set-up data. 
     In another embodiment of the present invention, a musical instrument has micro-electro-mechanical system (MEMS) pressure sensors that translate an air pressure to an electrical voltage; a mouthpiece, with air passages and vent holes, to channel air to the pressure sensors; a digital to analog converter to measure an electrical output of the pressure sensors; a user interface that allows a user to control the instrument; a microprocessor, that reads an electronic signal from the pressure sensors; a software program, that directs the microprocessor to perform a specific operation; an on-board sound-synthesis system that converts the electronic signal to sounds of a variety of instruments; a battery that provides power to the instrument; a charging system that charges the battery; a pressure transducer that triggers and controls the dynamics of a synthesized sound; and a guard-band in the center of the pressure transducer&#39;s range that prevents notes from being accidentally played. The guard-band is can be increased or decreased. 
     In an embodiment, the mouthpiece is removable and replaceable, and is configurable with air passages varying in size, shape, number, and spacing therebetween. 
     In an embodiment, the instrument has a body, wherein a portion of the body is recessed on a front edge, forming a cavity that has a lower surface, wherein the cavity receives the mouthpiece; a groove in the exterior bottom surface of the mouthpiece, in which the groove extends the length of the mouthpiece; and a tongue extending upward from the lower surface of the cavity. The tongue and groove mate with one another when an end of the mouthpiece is inserted into, or removed from, an open end of the cavity. 
     In an embodiment, the musical instrument has a mating component behind the mouthpiece to provide a seal to the mouthpiece and an interface to the pressure sensors. There is no airflow through the pressure sensors. 
     In an embodiment, the musical instrument has a percussive mode, a non-percussive mode, and a third mode. In the percussive mode, the instrument plays a set of notes at a pre-determined volume of attack. In the non-percussive mode, the instrument plays each note based on an instantaneous air pressure at the mouthpiece. In the third mode, the instrument blends the percussive and non-percussive modes to play the notes, in which the notes have a pre-set trigger level. 
     In an embodiment, the musical instrument has a USB port that allows a user to charge the battery, and upload and download information. 
     In an embodiment, the musical instrument has on-board memory, allowing a user to save instrument set-up data. 
     In another embodiment of the present invention, a musical instrument has micro-electro-mechanical system (MEMS) pressure sensors that translate an air pressure to an electrical voltage; a mouthpiece that is removable and replaceable, and has air passages and vent holes, to channel air to the pressure sensors; a digital to analog converter to measure an electrical output of the pressure sensors; a user interface that allows a user to control the instrument; a microprocessor, that reads an electronic signal from the pressure sensors; a software program, that directs the microprocessor to perform a specific operation; an on-board sound-synthesis system that converts the electronic signal to sounds of a variety of instruments; a battery that provides power to the instrument; and a charging system that charges the battery. 
     In an embodiment, the mouthpiece is configurable with air passages varying in size, shape, number, and spacing therebetween. 
     In an embodiment, the instrument has a body, wherein a portion of the body is recessed on a front edge, forming a cavity that has a lower surface, wherein the cavity receives the mouthpiece; a groove in the exterior bottom surface of the mouthpiece, in which the groove extends the length of the mouthpiece; and a tongue extending upward from the lower surface of the cavity. The tongue and groove mate with one another when an end of the mouthpiece is inserted into, or removed from, an open end of the cavity. 
     In an embodiment, the musical instrument has a mating component behind the mouthpiece to provide a seal to the mouthpiece and an interface to the pressure sensors. There is no airflow through the pressure sensors. 
     In an embodiment, the musical instrument has a percussive mode, a non-percussive mode, and a third mode. In the percussive mode, the instrument plays a set of notes at a pre-determined volume of attack. In the non-percussive mode, the instrument plays each note based on an instantaneous air pressure at the mouthpiece. In the third mode, the instrument blends the percussive and non-percussive modes to play the notes, in which the notes have a pre-set trigger level. 
     In an embodiment, the musical instrument has a USB port that allows a user to charge the battery, and upload and download information. 
     In an embodiment, the musical instrument has on-board memory, allowing a user to save instrument set-up data. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  shows a perspective view of the enclosure that houses the electronics, air pressure sensors, and power supply for the device, according to an embodiment of the present invention; 
         FIG. 2  shows a bottom plan view of the interior of the instrument; according to an embodiment of the present invention; 
         FIG. 3  shows a perspective view of the instrument, with a removable eleven holed mouthpiece, according to an embodiment of the present invention; and 
         FIG. 4  shows a diagram of the analog/digital programmable system, which may be located on a chip, according to one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The current invention requires no reeds, there is no airflow through the sensor, and there are no moving parts in the air stream. 
     The mouthpiece, containing multiple holes, channels air to pressure sensors, which then translate that pressure to electrical voltages. To provide a simulation of the airflow through the mouthpiece (bleed), similar to a harmonica, holes are provided which can be tailored to the player&#39;s individual needs. The mouthpiece is removable and replaceable allowing for different hole spacing, shapes and bleed. Unlike mouthpieces designed for separate passages for blow and draw, the use of an ambient-referenced pressure sensor eliminates the need for separate passages and sensors, making the mouthpiece that is simple in design. 
     Behind the mouthpiece is a mating component, which provides a seal to the mouthpiece, and an interface to the pressure sensors. The sensors, referenced in above, are ambient-referenced, and convert the pressure from each hole into a DC voltage, which is read by a digital to analog converter. 
     The device described in this patent is not being used to measure and reproduce a vibration, but to trigger and control the dynamics of a synthesized sound. 
     Utilizing programmable System on Chip technology, analog to digital conversion, as well as menu system, memory, USB I/O and MIDI I/O are implemented on a single chip. Within this chip, analog signals from the pressure sensors are converted to a digital signal. A processor reads the signals from the pressure sensors and, depending on the configuration of the instrument, plays on-board sounds, sends MIDI signals to an external synthesizer, or both. 
     The instrument is configured by means of a user interface, which allows it to play percussive or non-percussive sounds with equal facility. In the percussive mode, each instrument is played at a pre-determined volume of attack. In the non-percussive mode, the instrument plays each note based on the instantaneous air pressure at the mouthpiece. A third mode is a blend of each of these, with a pre-set trigger level for the note. 
     All notes are independent of each other; this results in the ability to play one note loudly, and one note softly—with a skilled player able to vary the amount of air being sent to adjacent holes. As well as independent volume information, each hole may be assigned an individual instrument. This would permit, for example, a player to play a bass on one side of the instrument, while using the other side to play a flute, strings, or other lead instrument. 
     To simulate the operation of a chromatic harmonica, a joystick is provided. Depending on the user&#39;s configuration of the instrument, the joystick can be used to shift notes up, down, or both. Unlike a typical chromatic harmonica, this feature permits a total of 66 notes in an eleven-hole instrument. 
     The joystick may be configured to offer other features as well, such as pitch-bend, program changes, insertion of effects, key changes and any other feature added to the harmonica. The user interface may consist of either an LCD screen and a rotary encoder for user input, or a touch-screen display. 
     On-board memory permits the user to save complete instrument set-up data, which may be recalled during performances, and accessed in real time by the joystick. When the instrument is configured as a sequencer, performance data may be recorded for future playback. 
     This instrument places sound synthesis within the body of the instrument. A headphone jack, as well as a line-out jack, permit the instrument to be used in privacy, or to be connected to an amplification system. 
     A USB port is part of the instrument that permits charging of internal batteries, and uploading or downloading settings, program information, or to upgrade the resident firmware as new features are developed. 
     Referring to  FIG. 1 , Body  102 : Approx. 6″×6″×1″ two-piece (top and bottom) enclosure with rounded filleted edges and corners. Body  102  (top) has holes cut out for LCD display  108 , joystick  110 , as well as rotary encoder  112  navigation and selector knobs. Body  102  has front end open with slot and tongue to allow insertion of removable and interchangeable mouthpiece  104  with matching groove. Preferred material is ABS plastic, brushed aluminum or exotic wood. Mouthpiece  104  has eleven holes or chambers but other models could have ten holes and as many as twenty holes that may vary in size and shape according to a players needs. Mouthpiece  104  is removable and replaceable so the instrument can be played by more than one player without the fear of germ transmission. There are eleven small air holes on the bottom of mouthpiece  104  located under each chamber to allow for inhaled and exhaled airflow adding more comfort and playability. Preferred material is ABS plastic, Delmar, or exotic woods. Approximate size is 6″×1″×⅜“. Air holes  106 . Round, square or hexagon shaped, approximately ¼” in diameter and 1″ in length. Holes  106  are evenly spaced and can be designed further apart or closer together depending on desired results. Closer holes may be used for chords and further spaced holes used for soloing. LCD Display  108  is backlit and used to display menu choices such as scale, key, instrument and so forth. Joystick  110  is used mostly in live performance mode to quickly change from pre-saved menu choices and also used as a pitch bend up or down allowing full chromatic scales. Joystick  110  may be further used to add effects such as tremolo, vibrato, or distortion. Rotary encoder  112  is designed to access menu, scroll through menu items and add titles to favorite patches stored in various banks on chip. 
     Referring to  FIG. 2 , Processor system on chip  202 . MIDI out jack  204  for connecting to other MIDI instruments. Volume knob potentiometer  206  is used for adding or lowering volume. Audio out jack  208  for connecting to an outboard amplifier or PA system. Power switch  210  for turning instrument on and off. Headphone jack  212  for connecting headphones. USB jack interface  214  for connecting to computer for updates and program changes. Display connector  216  connects LCD display via ribbon cable. Power supply area  218  contains voltage regulator and battery. Audio processing area  220 . On board synthesizer  222  for internal sounds. User interface jack  224  as an optional way to communicate with computer. Sensor PCB connector  226  for ribbon cable to connect to sensor board. Sensor connector  228  connects sensor board to main PC board. Sensor PC board  230  housing air pressure sensors and caps and filters. Pressure sensors  232  used to detect change in air pressure that determines how loud or soft a note or sound will be played. Sensor manifold  234  aligns and holds sensor nipple for exact match up with removable mouthpiece. Tongue  236  accepts the groove on bottom of replaceable mouthpiece and assures sealed alignment with mouthpiece. Lower half of body enclosure  238 . Main circuit board  240  houses and interconnects all components and power supply. 
     Referring to  FIG. 3 , mouthpiece  302  is shown bottom-side up to reveal slot for mating to enclosure. Mouthpiece  302  with eleven holes evenly spaced. Number of holes could vary when additional notes or sounds are needed. Shapes of holes may be round, square oval, or hexagon shaped. Preferred material is ABS plastic but works well with exotic woods and other plastics. As shown in drawing mouthpiece  302  is totally removable and can be replaced with different configurations of spacing and shapes of shafts. Slot  304  running the length of mouthpiece  302  designed to mate with tongue  236 . Tongue  236  which is part of lower half of enclosure  FIG. 2 . Designed to mate with groove or slot in mouthpiece  302 . Channel  308  cut into upper and lower enclosure  FIG. 1 . Channel  308  designed to accept removable mouthpiece  302 . 
     Referring to  FIG. 4 , input signals from individual sensors and the Joystick multiplexed and converted to digital via the Delta Sigma Analog to Digital converter. A control register is used to address the multiplexer, selecting the desired input signal. In those systems where the input device is a rotary encoder, a quadrature decoder is utilized to determine the user activity at that device. Inputs from the pushbuttons are read via a status register. The Character LCD segment controls the LCD display. A similar segment of hardware will control a color LCD touch-screen display in those models. EEPROM is utilized to save user settings. 
     The combination of the UART and a second control register are utilized to send MIDI information, selectively, to either the internal or an external synthesizer.