Symbol input device, image forming apparatus including the symbol input device, and method for inputting symbols

A symbol input device comprising:

• a plurality of symbol keys for inputting symbols including characters and numerals, each of the symbol keys being assigned one symbol;
• a correction key for correcting input symbols;
• a time keeping portion for measuring a time for which the symbol key is pressed and held;
• a storage portion for storing data;
• and
• an input receiving portion which
• recognizes that the symbol key or the correction key is pressed so as to accept input with the symbol key or the correction key,
• recognizes the time for which the symbol key is pressed and held based on the measurement by the time keeping portion,
• accepts, on condition that the time for which the same symbol key is pressed and held exceeds a predetermined long press time, periodic, automatic re-input of a symbol so long as the symbol key keeps being pressed beyond the predetermined long press time,
• refers to, when the correction key is pressed after the re-input performed automatically, the number of times that the correction key has been pressed,
• controls the storage portion to update the number of correction times that is the accumulated number of times that the correction key has been pressed after the re-input,
• increases the long press time every time when the number of correction times reaches a predetermined first number of times, and
• resets the number of correction times when the long press time is increased, wherein
• the input receiving portion controls the storage portion to update a normal input number of times, which is an accumulated number of times that mutually different characters, numerals, or symbols have been input each without exceeding the long press time,
• every time the normal input number of times reaches a second number of times, the input receiving portion decreases the long press time,
• when the input receiving portion decreases the long press time, the input receiving portion also resets the normal input number of times, and
• one or both of a longest time as a higher limit of the long press time and a shortest time as a lower limit of the long press time are determined in advance.