Note sensing in M.I.D.I. guitars and the like

• US 5,033,353 A
• Filed: 02/02/1990
• Issued: 07/23/1991
• Est. Priority Date: 04/14/1988
• Status: Expired due to Fees

• Current Assignee: Beehler & Pavitt
• Original Assignee: Ajay K. Keshap, Jay T. Barbeau, Joseph M. Fala, Mark S. Doerning
• Inventors: Fala, Joseph M., Keshap, Ajay K., Barbeau, Jay T., Doerning, Mark S.
• Primary Examiner(s): Witkowski, Stanley J.
• Application Number:
  US07/474,650
• Time in Patent Office: 536 Days
• Field of Search: 84/723-746, 84/DIG. 24, 84/DIG. 30, 84/267
• US Class Current: 84/72
• CPC Class Codes: G10H 1/0066 using a MIDI interface
• CPC Class Codes: G10H 2220/181 by nonresonant wave interaction, i.e. string sensing using wavelengths unrelated to string resonant wavelengths, e.g. ultrasonic waves, microwave or light waves, propagated along a musical instrument string to measure its fret length, e.g. for MIDI transcription
• CPC Class Codes: G10H 3/18 using a string, e.g. electric guitar mechanical features G10D1/085
• CPC Class Codes: Y10S 84/30 Fret control

Abstract

In a guitar or the like where fretting is detected by ultrasonic signals emitted by a transducer bridge and reflected at a point of each string held against a fret, and the same transducer bridge is responsive to audible frequency string vibration induced by a player, a damper bridge selectively dampens propagation of lower frequency vibrations from a note triggering string section adjacent to the bridge to a note selecting string section extending over the fretted neck, thereby minimizing intereference between fret detection and note triggering functions using a single set of string and a single acoustic transducer for each string.

Claims

1. A stringed musical instrument having one or more strings extending between an ultrasonic transducer bridge mounted on an instrument body and a fretted neck extending from said body, circuit means associated with said transducer bridge for determining the string length between said bridge and a clamped point of each said string on said fretted neck and for triggering notes responsive to audible frequency vibration of said strings, and vibration damping means intermediate said fretted neck and said transducer bridge, said damping means comprising silicone rubber material characterized by substantial transparency to ultrasonic signals propagating acoustically along said strings for damping propagation of string vibrations in the audible frequency range, said damping means thereby dividing each of said strings into a note triggering section between said damping means and said transducer bridge, and a note selecting section extending over said fretted neck.

2. The instrument of claim 1 wherein said damping means include resilient means normally urged into contact against each said string.

3. The instrument of claim 2 wherein said damping means includes means defining a low friction surface in contact with said one or more strings whereby each string may readily slide laterally on said low friction surface during string bending by a player.

4. The instrument of claim 1 wherein said means defining said low friction surface is a low-friction material applied on said rubber material.

5. The instrument of claim 1 wherein said ultrasonic bridge comprises means for anchoring one end of each string to said instrument body, an ultrasonic transducer in contact with each string, first muter means for substantially muting ultrasonic acoustical signals between said transducer and said one end and second muter means substantially transparent to ultrasonic acoustical signals on said strings for protecting each said transducer against low frequency shock vibrations imparted to said note triggering sections during musical play.

6. The instrument of claim 5 wherein each said transducer is supported on a pad of resilient material and urged by said pad into positive contact with one of said strings.

7. The instrument of claim 6 wherein each transducer is a disc including a slotted head screw threaded into said disc, said one string being received in said screw head slot.

8. The instrument of claim 7 further comprising transducer damping means for attenuating ultrasonic ringing of said transducer following acoustical excitation.

9. The instrument of claim 8 wherein said transducer damping means comprise adhesive means securing said transducer to said pad.

10. The instrument of claim 1 wherein said bridge includes a plurality of ultrasonic disc transducers, each said transducer including a slotted head screw threaded into said disc, each transducer supported on a pad of resilient material and urged by said pad into positive contact with one of said strings, said one string being received in said screw head slot.

11. A MIDI stringed musical instrument having a plurality of strings extending between an ultrasonic transducer bridge mounted on an instrument body and a head on a fretted neck, first circuit means associated with said transducer bridge for determining the length between said bridge and a clamped point of each said string on said fretted neck by means of ultrasonic signals propagated along said strings thereby to derive a note select output, second circuit means for deriving a note triggering output responsive to audible frequency range vibrations of each said string, and a damper bridge including resilient material supported in vibration damping contact with each of said strings, said resilient material being selected to dampen propagation of low frequency string vibrations across said contact to a significantly greater degree than acoustical propagation of ultrasonic signals on said strings, said damper bridge thereby dividing said strings into a note triggering section between said damper bridge and said transducer bridge, and a note selecting section extending over said fretted neck.

12. The instrument of claim 11 wherein said resilient material includes a low friction surface to facilitate lateral sliding of said strings on said resilient material during string bending by a player.

13. The instrument of claim 12 wherein said resilient material is silicone rubber characterized by substantial transparency to propagation of ultrasonic acoustical signals across said contact.

14. The instrument of claim 13 wherein said low friction surface is a low-friction material applied on said silicone rubber.

15. A MIDI stringed musical instrument having a plurality of strings extending between an ultrasonic transducer bridge mounted on an instrument body and a head on a fretted neck, circuit means associated with said transducer bridge for determining the length between said bridge and a clamped point of each said string on said fretted neck by means of ultrasonic signals propagated from said bridge, means for triggering a note output responsive to lower frequency vibration of said strings, and a damper bridge dividing said strings into a note triggering section adjacent to said transducer bridge and a note selecting section extending over said fretted neck, said damper bridge including a strip of silicone rubber supported against and transversely to said strings so as to dampen propagation of low frequency vibrations resulting from note triggering by a player propagating from said note triggering section to said note selecting section to a significantly greater degree that ultrasonic vibrations of said strings, and means interposed between said silicone rubber and said string for providing a low friction surface to facilitate lateral sliding of said strings over said strip during string bending by a player.