[54] PORTABLE DISPLAY DEVICE WITH AT
LEAST TWO DISPLAY SCREENS
CONTROLLABLE COLLECTIVELY OR
SEPARATELY
[75] Inventors: Yoshinori Kuno, Saitama; Noboru
Tanabe; Koichi Hasebe, both of
Kanagawa, all of Japan
[73] Assignee: Kabushiki Kaisha Toshiba, Kawasaki, Japan
[21] Appl. No.: 411,924
[22] Filed: Mar. 28, 1995
Related U.S. Application Data
[63] Continuation of Ser. No. 113,637, Aug. 31, 1993, abandoned.
[30] Foreign Application Priority Data
Aug. 31, 1992 [JP] Japan 4-230732
[51] Int. CI.6 G09G 3/02
[52] U.S. CI 345/1; 345/901; 345/903
[58] Field of Search 345/1, 2, 3, 173,
345/179, 901, 903; 358/449
[56] References Cited
U.S. PATENT DOCUMENTS
4,631,596 12/1986 Yaguchi 358/449
4,746,981 5/1988 Nadan 345/1
4,876,657 10/1989 Saito 345/1
4,884,068 11/1989 Matheny 345/1
5,049,862 9/1991 Dao 345/179
5,128,662 7/1992 Failla 345/903
5,184,956 2/1993 Langlais 345/1
FOREIGN PATENT DOCUMENTS
2-77085 3/1990 Japan 345/3
2- 257364 10/1990 Japan.
3- 217959 9/1991 Japan.
9105327 4/1991 WEPO 345/173
Primary Examiner—Richard Hjerpe
Assistant Examiner—Matthew Luu
Attorney, Agent, or Firm—Foley & Lardner
[57] ABSTRACT
A portable display device capable of presenting a document in an easy to read format, in which a simultaneous display of different parts of the document in reasonable sizes can be made, by a simple operation of the device. The display device comprises a document memory for storing documents to be displayed, at least two display screens for displaying the documents stored in the document memory means, and a display control unit for controlling displays of the documents on the display screens to be in a linked mode in which the displays on the display screens are linked together and in a separate mode in which the displays on the display screens are independent from each other.
