05400093 is referenced by 52 patents and cites 10 patents.

An image projection device comprising at least one display panel (26, 27, 28), a projection lens system (C) and a focus error detection system (FS) is described. Since the radiation source (50) and the radiation-sensitive detector (51) of the focus error detection system are arranged in planes which effectively coincide with the plane of the display panel (28), and a focus measuring beam b traverses the projection lens system twice on its path to and from a projection screen (D), an accurate and reliable focus error signal (S.sub.f) is obtained.

Title
Image projection system with autofocusing
Application Number
8/171951
Publication Number
5400093
Application Date
December 21, 1993
Publication Date
March 21, 1995
Inventor
Wilhelmus A G Timmers
Eindhoven
NL
Agent
Norman N Spain
Assignee
U S Philips Corporation
NY, US
IPC
G03B 21/53
View Original Source