Position sensing device

An operation position sensor device for an electronic musical instrument, comprising:

• an operation member;
• a light emitting section;
• a photodetecting section;
• a light amount controlling member that is placed in an optical path between the light emitting section and the photodetecting section, and controls the amount of light inputted from the light emitting element to the photodetecting section according to an operation position of the operation member;
• and
• an operation position sensor section that detects the operation position of the operation member based on the amount of light received by the photodetecting section,
• wherein the amount of light to be controlled by the light amount controlling member continuously or generally continuously changes in a first direction when the operation position is within at least one predetermined operation position zone, corresponding to changes in a predetermined direction of the operation position of the operation member, and discretely changes in a second direction opposite to the first direction when the operation position moves from outside of the predetermined operation position zone to the predetermined operation position zone or the operation position moves from the predetermined operation position zone to outside of the predetermined operation position zone;
• and
• the operation position sensor section judges, when the amount of light detected by the photodetecting section changes more than a predetermined value, that the operation position of the operation member has moved from outside the predetermined operation position zone to the predetermined operation position zone or the operation position has moved from the predetermined operation position zone to outside the predetermined operation position zone.

A method for detecting an operation position of an operation member in an electronic musical instrument, comprising:

• determining that an amount of measured light resulting from the depression of the operation member has changed in excess of a predetermined difference value a number of times;
• determining a difference value of clock counts measured at a last two determinations that the measured light changed in excess of the predetermined difference value in response to determining that the amount of the measured light has changed in excess of the predetermined difference value the number of times;
• converting the difference value to a key depression speed;
• and
• issuing a sound generation command based on the key depression speed to a sound source.

An electronic musical instrument, comprising:

• an operation member;
• a light emitting section;
• a photodetecting section;
• a light amount controlling member that is placed in an optical path between the light emitting section and the photodetecting section, and controls the amount of light inputted from the light emitting element to the photodetecting section according to an operation position of the operation member;
• and
• a processing component that performs operations, the operations comprising:
• determining that an amount of measured light resulting from the depression of the operation member, received from the photodetecting section, has changed in excess of a predetermined difference value a number of times;
• determining a difference value of clock counts measured at a last two determinations that the measured light changed in excess of the predetermined difference value in response to determining that the amount of the measured light has changed in excess of the predetermined difference value the number of times;
• converting the difference value to a key depression speed;
• and
• issuing a sound generation command based on the key depression speed to a sound source.