Average Co-Inventor Count = 4.00
ph-index = 2
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. Nippon Telegraph and Telephone Corporation (2 from 5,290 patents)
2. Nitsuko Corporation (2 from 86 patents)
2 patents:
1. D314374 - Key telephone set
2. D301578 - Telephone handset