Patents Examined by Ricky Moch
  • Projection lens assembly and projection display apparatus
    Patent number: 5539579
    Abstract: An optical system of a projection display apparatus includes a projection lens assembly having a first lens group having a negative power, a second lens group having a negative power and a third lens group having a positive power, all arranged in this order from a side of a screen. An air space is provided between the first and second lens groups and also between the second and third lens groups. Each air space is longer than the entire length of the second lens group as taken along the optical axis of the assembly.
    Type: Grant
    Filed: November 15, 1994
    Date of Patent: July 23, 1996
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Yoshito Miyatake, Yuichi Kimura, Sinya Sannohe, Yoshimasa Fushimi