The invention relates generally to character displays, such as those used to display numeric values in various human machine interface (HMI) devices. More specifically, this invention relates to a method for optimally arranging characters outside of expected character size limitations commonly encountered by such displays.
In most HMI devices, or any system that presents information or data to an operator using such devices, a screen for displaying such information or data is provided as a part of the device. The screen usually has a fixed width and height, and may consist of several display areas, each displaying different character data or numeric values. In order to display information to an operator, the display areas are updated with new data or values, providing necessary operation information that reflects changing parameters or information.
In addition to the necessary character data or numeric values displayed during operation of the device, the screen must display all other relevant information to the operator, and additionally may provide for control of the HMI device or remote equipment. Because the area of the screen is limited by the fixed width and height, the display areas (e.g., for each digit or character to be displayed) must fit into specifically allocated areas in order to best utilize the available screen area, yet must be large enough to be legible to the operator and display all expected character data or values.
Each individual display area must be of sufficient area to provide optimal legibility to the operator, constraining the minimum size of the display. The display areas are commonly configured to display the largest expected data or value (e.g., number of digits or characters), even if this data or value rarely occurs. The restrictions of available screen area, legibility requirements, and provisions for largest expected data or values all serve to constrain the dimensions of the display areas.
Problems may occur with the display areas if the data or value to be displayed exceeds the allocated space of the display area. Commonly, such values will either overrun the display area or truncate and appear as incomplete or corrupted values. Neither action provides optimal handling of the excessively large values. If the excessively large value overruns the allocated space of the display area, adjacent display areas or view elements will be resized and/or corrupted. Truncated or clipped values often include a clipping character, such as an asterisk, to alert the operator that the value has exceeded the display. However, the operator is still unable to obtain the value. There is a need, therefore, for a technique for that adjusts displays of characters or numeric values to allow complete display of all data or values within an appropriate allocated display area.