US 7,009,617 B2Granted

On-screen display device

AssigneeMatsushita Electric Industrial Co., Ltd.

InventorsSatoru Kotani, Toshihiko Maruoka, Keisuke Tanaka

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Abstract

An on-screen display device that can effectively utilize a video RAM area. This on-screen display device includes a video RAM that holds character data of desired characters that are to be displayed; a display character setting unit for locating the number of bits as many as the remainder that is obtained by dividing character data corresponding to one character by the number of bits that can be read at one-time access from the video RAM, collectively by one line in the video RAM; buffers for storing a part of character data of the respective characters; a character generator ROM for outputting font data corresponding to the character codes; and a display control unit for reading character data from the video RAM via the buffers at the display of the characters, and reading the font data that are created by the character generator ROM, thereby outputting an on-screen output signal.

Claims8

Dependent claims

An on-screen display device for displaying desired characters on a display, character data of one character being composed of R bits (R is an integer that is equal to or larger than 2), and the character data comprising character codes that indicate types of the characters, or attribute codes that indicate modification display of the respective characters and character codes that indicate types of the characters, including:

a video RAM that holds the character data of the desired characters that are to be displayed on the display;
a display character setting unit for writing the character data at predetermined positions in the video RAM;
a first buffer that reads r bits (1≦r<R) of respective m pieces (2≦m≦M) of the character data selected from among M pieces (2≦M) of the character data corresponding to characters that are displayed on one line, from the video RAM at one-time access, and stores the read data;
a second buffer that stores remaining (R−r) bits of the respective m pieces of the character data;
a character generator ROM for creating font data corresponding to the character codes included in the character data that are outputted from the first and second buffers;
and
a display control unit for reading the font data from the character generator ROM and generating a desired on-screen output signal on the basis of the font data.

4 more elements

Dependencies are inferred from the claim text.