Electronic fingerboard for stringed instrument

The present invention relates to an interface for controlling a musical instrument synthesizer. In one aspect, the present invention allows musicians familiar with stringed instruments to use their musical skills to control electronic music synthesizers.

According to one aspect of the invention, a synthesizer controller based on a guitar interface is provided, but the invention is not limited to use with a guitar and can be used for other shape factors of stringed instruments. ..

In a typical stringed instrument, there are two ways to produce and control the sound. The first means controls the loudness or the first consonant of the tone, and the second means controls the pitch of the tone. In conventional mechanical or electromechanical stringed instruments, control is performed by striking, pinching, or bowing the strings with one hand to provide head consonants and loudness. The fingers of the other hand are used to terminate the length of the strings and define the pitch of the sound.

Two types of interfaces are commonly known for electronic stringed instruments. The first type is based on pitch extraction using an electromagnetic pickup, a piezoelectric pickup, or an optical pickup connected to each string. This pickup converts the vibration of the strings into an electronic signal, and uses a combination of hardware signal adjustment and software algorithms to convert the electronic signal into information that can be transferred to a music synthesizer. This may usually be a MIDI (Musical Instrument Digital Interface) device. However, this method is characterized by a physical delay between the time it takes to pluck the strings and the time it takes to produce the resulting sound. This delay is due to the fact that a significant portion of the electronic waveform must be analyzed before the results can be calculated and transmitted. On a typical guitar, the 6th string is about 82.4 hertz, so a single cycle of this waveform is 12.1 ms. In a typical system, it is necessary to acquire more cycles than a single cycle before the pitch can be accurately determined, which causes an unpleasant delay for the musician.

The second method is based on the switch set on the neck of the instrument combined with the trigger set. Use the switch on the neck to determine the pitch of the note you are playing. Use a trigger to pluck or strumm the strings to pick up the first consonant of the note. The problem with this type of system is that for musicians familiar with traditional guitars, the neck switch isn't like a guitar and it's expensive to put on.

According to one aspect of the present invention, an electronic musical instrument that produces a musical sound is provided, which is: a head consonant signal sensor that detects the start of a sound played by the electronic musical instrument; and a sound detected by the sensor. An electronic fingerboard that determines the pitch is provided, and the electronic fingerboard includes a first film layer, a second film layer, and a spacer member between the first and second film layers, and the first and second film layers are provided. A first inactive position where the layers are separated from each other along their respective lengths, and a second where the first and second layers are in contact with each other at a user-selected point along their respective lengths. The first and second layers are movable relative to each other and the pitch is determined by the resistance between the first and second layers at a user-selected point.

Preferably, the head consonant sensor comprises a piezoelectric sensor or an optical sensor.

In one embodiment, the instrument is a guitar; the fretboard is attached to the elongated neck; the frets are laterally formed on the neck; the elongated structure corresponding to the strings of the guitar is above the neck. The first layer, the second layer and the spacer member are formed under each elongated structure.

Preferably, the first layer is a conductive strip and the second layer is a resistance strip. The conductive strips are made of carbon-plated silver ink for resistance and the resistance strips are made of carbon. In one form, the conductive strip is on top, the resistance strip is below the conductive strip, and the spacer member is formed between them. In one embodiment, the conductive strips are made up of two electrodes interlocking with each other.

In one aspect, the elongated structure corresponding to the strings of the guitar comprises linear raised ribs on the fingerboard. Quantization mode, legato mode, or absolute mode is used to determine the pitch of the sound.

Preferably, the user-selected point provides a controllable resistor that represents the pitch of the sound by its position on the fingerboard. The head consonant signal sensor is triggered by plucking the strings of an instrument.

Preferably, a microprocessor is provided for sequentially reading and processing the signal from the signal sensor and the electronic fingerboard to determine when the sound was played, as well as the volume and pitch of the sound. The microprocessor sends data about the played sound to a MIDI interface or an internal wavetable synthesizer.

Preferably, the first and second layers have a terminal at one end thereof, and the voltage of the terminal is determined by a point selected by the user. The voltage at this terminal is proportional to a user-selected point along the first and second layers, at which point the first and second layers are shorted to each other.

In one aspect, the first and second layers include force-sensing resistors, which change the resistance as the pressure at the user-selected point changes, and the higher the pressure at the user-selected point, the higher the pressure. , The contact area between the first and second layers becomes large. In addition, the measurement of the played sound is repeated a programmed number of times to determine the exact pitch of the played sound.

In one embodiment, the fingerboard comprises a plurality of conductive electrode surfaces, each of which is used to detect the pitch of sound at one or more predetermined positions on the fingerboard. Two electrode surfaces are provided alternately, and each of these two surfaces corresponds to a user-selected point when located on the alternate frets on the fingerboard.

According to another aspect of the present invention, an electronic musical instrument that produces a musical sound is provided: an electronic fingerboard that determines the pitch of the sound, the electronic fingerboard being the first film layer and the second. A first inactive position in which a spacer member is provided between the film layer and the first and second film layers, and the first and second layers are separated from each other along their respective lengths. The first and second film layers are movable relative to each other between the first and second layers and the second active position where they are in contact with each other at a user-selected point along their respective lengths. The pitch is determined by the resistance between the first and second layers at a user-selected point.

According to another aspect of the present invention, a method of playing an electronic musical instrument that produces a musical sound is provided, which method: driving a head consonant signal sensor that detects the start of a sound played by the electronic musical instrument. And; with a step of applying pressure to one or more points selected by the user on the electronic fingerboard to determine the pitch of the sound detected by this sensor, the electronic fingerboard is the first film layer. A first inactive position in which a spacer member is provided between the second film layer and the first and second film layers, and the first and second layers are separated from each other along their respective lengths. And the second active position where the first and second layers are in contact with each other at a user-selected point along their respective lengths, with the first and second film layers relative to each other. It is movable and the pitch is determined by the resistance between the first and second layers at a user-selected point.

According to one aspect of the invention, the system of the invention is an improvement on the principle of the second interface described above using separate sensors for pitch and head consonants and is based on this principle. Head consonants can be achieved in a variety of ways using magnetic sensors, piezoelectric sensors, Hall effect sensors, optical sensors, or other sensors. The pitch control means of the present invention uses a technique that can be generally described by applying the principles used in computer touch screens using resistance techniques instead of the numerous switches on the neck. In one embodiment of the present invention, a resistance sensor is used to simulate a string. The resistance generated by the sensor is proportional to the position along the length of the sensor, at which position the user drives the sensor. The resistance sensor is read by an analog-to-digital converter. The converter is controlled by a microcontroller, and when the player presses the sensor, the length of the termination determines the reading of the resistor and drives the given sound.

The system of the present invention, in one form, provides a mechanism familiar to guitar players and musicians with the skills to play stringed instruments. In addition, the resistant fingerboard of the present invention can be reinforced by a linear raised surface to provide tactile feedback that gives the sensor at the neck of the instrument a sensation similar to that of a traditional stringed instrument. This raised surface is, by way of example, using printing techniques, by adding plastic ribs along the sensor length, or by embossing the raised shape on the sensor material, or , Can be mounted or formed by adding an embossed overlay layer. By providing a raised surface, it is possible to simulate the sensation of the strings and, if necessary, the sensation of the frets.

The system of the present invention has the following advantages:

(1) Pitch detection method The device of the present invention does not have the inherent delay problem of the pitch detection algorithm. The resistance value of the string sensor can be read instantly by the control microprocessor.

(2) Switch method This switch interface is unfamiliar to musicians trained to use stringed instruments. Pressing the switch is a foreign experience and requires retraining. Therefore, one aspect of the present invention can provide a performance experience similar to or familiar to the performance experience of a conventional stringed instrument. In addition, the system of the present invention is simpler and more efficient than that of a multi-switch system, resulting in lower potential costs and cost advantages. Also, the ability to provide mechanical ribs or rails is very similar to a regular stringed instrument such as a guitar, thus providing the performer with tactile feedback that is close to the strings.

Another aspect of the invention is that a constant current source can be used to activate the sensor, resulting in a linear response from the sensor without the need to provide electrical connections on both sides of the resistor strip. is there. Preferably, the sensor has two conductors, namely a conductive strip and a resistance strip. The signal is measured directly at the terminal of the resistance strip. This makes the structure of the resistance sensor simpler. The system is also preferably configured such that the conductive silver strips are physically placed on top of the carbon strips. This conductive strip is connected to the ground potential and therefore also provides a shield that reduces noise pickup in the system.

The device arranged and configured according to the present invention is played like a general conventional guitar. The sound is fingered on the neck of the guitar, and the string trigger can be plucked or strummed using normal guitar playing.

Several modes of operation of the invention controlled by a microcontroller are provided and can be used to enhance music performance. A typical example of such a mode will be described below.

Operation mode example In quantization mode, the pitch is determined when the string trigger is driven. The pitch of the first transmitted sound is quantized to the value of the most recent actual sound (1/2 step). When the user slides his or her finger along the fingerboard, an adjacent sound (1/2 step) corresponding to the new finger position is heard.

In legato mode, the pitch is determined when the string trigger is driven. The pitch of the first transmitted sound is quantized to the value of the most recent actual sound (1/2 step). When the user slides his finger along the fretboard, the system uses a pitch bend command to modify the pitch of this note to correspond to the new fretboard position relative to the first consonant position. This mode provides a control mechanism similar to a guitar pitch bend where the strings are bent. This allows for a smooth transition of the pitch value of the sound, and also facilitates the ability of the user to perform pitch vibrato by rocking his or her finger back and forth to fine-tune the pitch. This cannot be done in switch-based systems.

In absolute mode, the pitch is determined when the string trigger is driven. The pitch of the first transmitted sound is transmitted according to the sound + pitch bend that matches the actual finger position on the fingerboard. This mode is like a fretless instrument, and the way it sounds always corresponds to its absolute position on the fingerboard. Even in absolute mode, you can adjust the vibrato as in legato mode. This cannot be done in switch-based systems.

Fingerboard layout The fingerboard layout shown in FIG. 1 is used in the embodiments of the present invention. It is described to substantially match the fingerboard of a conventional electronic stringed instrument. Many other configurations and scales are envisioned, which are within the scope of the present invention. In a conventional guitar neck, frets are provided at intervals proportional to the pitch of the sound generated by the fingerboard position. Since this system is an electronic system, the scale can be varied so that the frets or fret marks can be evenly distributed on the neck and narrower to provide a more compact system. The movement of the finger position to the actually generated pitch is determined by software using a look-up table, mathematical formula or similar means that can be varied to accommodate the tuning of various stringed instruments.

<figref num="1">FIG. 1 is a perspective view of a typical fingerboard designed for guitars.</figref><figref num="2A">FIG. 2A is an enlarged cross-sectional view of the fingerboard shown in FIG.</figref><figref num="2B">FIG. 2B is an enlarged cross-sectional view of a further embodiment of the fingerboard shown in FIG. 1, with an upper portion comprising two layers.</figref><figref num="3">FIG. 3 is a complete perspective view of the guitar.</figref><figref num="4">FIG. 4 is a circuit diagram of a basic electronic circuit that can be used in one embodiment of the present invention.</figref><figref num="5">FIG. 5 is a diagram showing an electronic component of the fingerboard.</figref><figref num="6">FIG. 6 is a diagram showing pitch detection using the present invention.</figref><figref num="7">FIG. 7 is a diagram showing pitch and pressure detection using the present invention.</figref><figref num="8">FIG. 8 is a diagram showing a stepwise resistance using the present invention.</figref><figref num="9">FIG. 9 is a perspective view showing a fretboard according to another aspect of the present invention.</figref><figref num="10">FIG. 10 is an enlarged perspective view showing the upper side of the fingerboard showing the raised half-rib shaped strings.</figref><figref num="11">FIG. 11 is an exploded view showing the fingerboard of the present invention shown in FIG. 1 so that various layers according to the present invention can be seen.</figref>

(Detailed description of the invention) FIG. 1 is a diagram showing a conventional fingerboard assembly 10 used in the system of the present invention. In the embodiment shown in this figure, a string 12 is provided on the upper layer of the fingerboard assembly 10, and an embossed fret 14 is provided on the surface 16 of the fingerboard assembly 10. Raised markers for strings 12 and frets 14 provide tactile feedback to the user. Strings 12 and / or frets 14 can be excluded from the design. The marking process of this embodiment is to emboss these mechanisms on the overcoat or surface 16 of the fingerboard assembly 10. Other methods include silk screening this mechanism with resistant epoxy-based inks. In another embodiment, a semi-circular brass rib is used, which is glued to the fret end or surface along the length of the neck 18 to simulate the tactile sensation of the string 12. ..

FIG. 2 is an exploded cross-sectional view of the fingerboard assembly 10 according to the present invention. An upper polyester film 22 and a lower polyester film 24 are provided, and these films are separated by an adhesive spacer layer 26. The upper film 22 is a strip 28 of silver conductive ink, which is coated along the length below the string 12 to form a ground electrode. The lower film layer 24 is covered with a strip of resistant carbon ink 30 to form a conductive electrode. The spacer 26 creates a series of gaps 32 between the silver conductive ink 28 and the resistive carbon ink 30, so that these inks do not contact each other in the normal resting position. When the user touches any position along the line of the string 12, the carbon resistant ink 30 contacts the silver conductive ink 28 and the resistor terminates at a value proportional to the position in contact with the fingerboard. This provides a controllable resistor that represents the pitch of the musical sound according to the position of the user's finger on the string.

FIG. 3 shows the appearance of an embodiment of the present invention. The fingerboard 40 is located along the neck 42 of the instrument, giving it the look and feel of a traditional guitar 44. The piezoelectric sensor 48 is located on the bridge 46. These sensors 48 provide head consonants to the control electronic components. These components are driven when the user strumms or plucks the string trigger 50.

FIG. 4 is a block diagram of the system electronic component of the present invention. Each resistor strip 62 is powered by a constant current source 60 to ensure that the response of the resistor strip 62 is linear. The terminal voltage of the resistor strip 62 is determined by its position along the length of the carbon strip 62 in contact with the silver ground strip 66. The signal from this point is tuned and sent to the multiplexer 68, whose input selection is controlled by the microprocessor 70. The output of the piezoelectric sensor element 72 is also sent to the multiplexer 68. The microprocessor 70 sequentially reads the voltages of the resistance strip 62 and the string trigger 80. This data is used to determine when to make a note, how loud and pitch the note should be. Once the software determines the sound, it selectively sends out this data via MIDI interface 76, or in this example, the built-in internal wavetable synthesizer 78 triggers the sound.

FIG. 5 is a schematic view showing the resistance sensor 90 described above with respect to FIG. This figure shows the mechanical structure in the form of a schematic. The conductive strip 66 is connected to the signal ground, the resistor strip 64 is connected to the current source, and the terminal 62 is connected to the analog-to-digital converter. If not driven, the voltage at terminal 62 is raised to the power supply voltage. When the conductive strip 66 comes into contact with the resistance strip 64, a current flows through the resistance strip 64 between the terminal 62 and the grounded point. The voltage generated at terminal 62 is therefore proportional to the position along the length of the two strips 64 and 66 that are short-circuited to each other.

In one preferred embodiment of the invention, the fret space for a stringed instrument can be determined to create a semitone with even space along the length of the neck. The distance between the frets is proportional to the 12th root of 2, which is exactly the scale. This requirement causes the upper frets of the neck to be very wide or farther apart, and the lower frets of the neck to be narrower or closer to each other.

This design does not require any special fret spacing and can be totally controlled by system software. According to the present invention, the fret spacing can be custom designed to provide optimal comfort to the performer, and it is easy to change from a wider fret spacing to a narrower fret spacing. ..

It can be evenly spaced using the present invention, but partly because it fits into the space of traditional musical instruments, and partly because the performer's hands are simple due to the human body mechanism. This is quite uncomfortable for a guitar player, as it tends to rotate as it moves along the length of the neck. Therefore, the present invention provides a more ergonomic, "comfortable" space, providing good access to all sounds across all scales of the neck.

In one embodiment of the invention, the difference between the standard fret spacing and the constant fret spacing may be distributed using an equation created for this purpose.

With reference to FIG. 6, pitch detection is shown in the figure, which is done by measuring the resistance between the upper (conductive) layer A and the lower (resistive) layer B. In FIG. 6, A is a silver conductive strip, B is a carbon resistance strip, and the resistance represents the pitch measured between points A and B.

In FIG. 7, C is the first silver conductive strip, D is the second silver conductive strip, while E is the carbon resistance strip. This resistance represents the pitch measured between points C and E, or between points D and E. In FIG. 7, the pattern on the layer of conductive silver is divided into two separate conductive electrodes. This electrode has fingers arranged alternately. The pitch resistance measurement is similar to that described in FIG. 6 above. In essence, the presence of two electrodes is ignored. Electronic components are programmed to measure the resistance between C and E (or D and E), and in fact this measurement shorts C and D to each other, shorting the silver and carbon electrodes ( It may be done by measuring the resistance between E).

Pressure measurement is performed by treating the device as a force-sensing resistor. Point E is driven by an electronic component and measurements are made between electrodes C and D. This resistance is altered by the user's finger contacting a larger area electrode with the carbon electrode or strip E.

Referring to FIG. 8, another embodiment of the system of the present invention is shown, in which a stepped shape is used for the resistance element. This stage occurs at the same location as the frets. With less resistance material welded to the fret positions, the change in resistance over these regions is greater. This allows the sound next to the fingerboard to be better distinguished.

One of the preferred responses produced by the present invention when changing from stationary (non-touch) to driven (touch) is that the measurements are made simultaneously. In the implementation state, the measured values may vary slightly at the beginning or end of the mechanism. Usually, a simple quality measurement can be performed by repeating the measurement and counting the number of repeatedly measured samples within a predetermined range. If the number of iterations is greater than the predetermined threshold, then this measurement is determined to be valid. The system will always be accurate if the number of iterations can be arbitrarily increased. For practical reasons, the number of repetitive samples should be limited so that the system responds in a timely manner.

An error condition may occur if the user does not maintain a constant pressure on the fingerboard. There are some cases where this is especially clear. (a) When the performer holds multiple note chords. Towards this chord end, the performer begins to reduce the pressure on the fingerboard in an uncontrolled state. (b) When the performer plays a very soft and subtle sound, it is not possible to apply good same pressure to the fingerboard.

Under these conditions, the system reports an error, usually with a lower measurement than predicted based on the first position.

If the event is not performed accurately by the player, the fingerboard may come into contact during the transition and may be disengaged and read and measured as a value below the desired value. This error is usually minor, typically a value in the range of a semitone of -1 (ie, one fret lower).

In order to maintain a rapid response to fingerboard changes, measurements cannot be increased over a very long period of time and some other method of determining this error condition is needed.

One solution to this situation is to configure the conductive electrodes on multiple surfaces to effectively divide the neck area. As an example of this, as shown in FIG. 9, a surface divided into two can be used. The two surfaces allow the scanning cycle to be divided into odd and even frets by alternating grounding and floating on these surfaces. This allows you to selectively scan odd and even frets. If the user presses an even fret, for example the 4th fret, the error measurement will report the sound corresponding to the 3rd fret. However, if the measurement is made on a driven even plane, this turns out to be an error.

The system can correct these errors. For example, if you are scanning even frets and the resistor reports an odd fret (eg the 3rd fret), this is recognized as an error and corresponds to the correct fret position (4th fret) for the first consonant of that note. It can be safely replaced with the measured value and the sound value. If corrected after the initial instability, the system software may also monitor this value.

This method can be made more accurate by increasing the number of treads to three, four, or any other number that is practical in this embodiment.

The system of the present invention is preferably based on a conventional membrane switch manufacturing method and simply has two layers (one conductive layer and one resistance layer) separated by an adhesive spacer. This spacer not only holds these layers together, but also provides a consistent separation between the conductors to drive the conductors when pressure is applied. No return or bridge conductor is required. All signals are detected from the return edge of the assembly.

In one form of the invention, pressure is measured using the same conductor set as the conductor used to measure pitch. Therefore, the present invention is cost effective and can be designed for mass production. The system of the present invention can provide pressure measurements individually for each string. In addition, a force detection resistance pattern is used, and no additional layer is required for pressure.

In one aspect, the invention describes an interface to a MIDI synthesizer (using a conventional MIDI din jack or a USB interface to a PC), or a built-in synthesizer.

The force-sensing resistance pattern used in the string sensor according to one aspect of the invention provides pressure sensitivity and provides separate pressure for each string. Other configurations only read a single pressure value. Further, the configuration of the present invention uses individually embossed fingerboards overlaid on the switch mechanism in one embodiment.

The present invention is generally simple and allows the ink screening process to be used on two separate substrates assembled with adhesive spacers. There are no "intervening conductor strips" or connections that need to be folded. Each conductive strip or resistance strip simply terminates within a connector at one end of the fingerboard, where all measurements are made. Therefore, the present invention does not use a folded band and does not have a signal return at a single end of the sensor.

In one form, the invention uses a piezoelectric sensor and a short string for trigger input. The use of a multiplexer is a standard electronic method and is based solely on hardware embodiments. That is, it depends on the usefulness of the analog-to-digital converter on the particular hardware selected.

As described above, the present invention provides a pressure sensor based on a force detection resistance pattern. It does not require any additional layers or materials. A separation layer is used for the tactile feeling of the strings. It is cheaper and easier to manufacture. In one embodiment, the present invention uses a polycarbonate overlay with both fret and chord functions embossed. This "string-like" feel is improved by implementing the fret function.