Average Co-Inventor Count = 2.57
ph-index = 3
The patent ph-index is calculated by counting the number of publications for which an author has been cited by other authors at least that same number of times.
Company Filing History:
1. Yamaha Corporation (3 from 5,451 patents)
3 patents:
1. 5248846 - Musical instrument incorporating a Helmholtz resonator
2. 5086686 - Keyboard instrument
3. 5031500 - Keyboard instrument