1. Field of the Invention
The present invention relates to a system for displaying keyed-in characters in electronic typewriter applications. More particularly, the invention involves a display device for an electronic typewriter which displays a scalable edit window and position indicators for the window, both of which facilitate operator preview of keyed-in characters while providing location information of the characters with respect to a recording medium.
2. Description of the Related Art
Conventional electronic typewriters include some sort of display screen on which keyed-in characters are displayed prior to printing. However, to identify the position at which displayed characters will be printed, it is necessary for the operator to refer to a horizontally-engraved ruler located adjacent the printer carriage, or to a cursor position marker located on the printer head. To perform this task, the operator must, however, switch his/her focus from the display screen, where edit and keying operations are displayed, to the ruler or marker. When several edit operations are necessary, such cross-reference between the display screen and a ruler or marker causes great inconvenience and results in reduced efficiency. In addition, since such conventional rulers or markers only provide horizontal position information, the operator cannot determine the vertical line position or vertical span of the printed characters with respect to the paper.
Thus, there exists a need for a system which displays on a single display device, the spatial relationship of keyed-in characters with respect to the recording medium selected for printing. In particular, there exists a need for a system which provides horizontal and vertical positional information of keyed-in characters, with respect to the recording medium selected for printing the characters, so that the format of the characters on the recording medium may be previewed prior to printing. There also exists a need for a display device which facilitates the display of characters of a variety of font sizes on a single line, including very large font sizes.
In addition, since electronic typewriters generally print each line of characters as soon as keying-in of the characters is complete, the typewriter display screen is usually large enough to display only a single line. Even though markers indicating the horizontal position of the keyed-in characters may be available prior to printing, since only a single line is displayed the operator is generally unable to visualize where on the recording medium the line will be printed. Thus, to visualize the document he/she is formatting, the operator must either print a draft of the document or project an inherently inaccurate mental image of the unprinted document. Inconvenience, delay and inaccuracy are the resulting consequences.
Thus, there exists a need to provide the operator of an electronic typewriter with assistance in visualizing where on a page keyed-in characters will be printed.