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Numeric keypad NumLock status management Disclosure Number: IPCOM000019710D
Original Publication Date: 2003-Sep-26
Included in the Prior Art Database: 2003-Sep-26
Document File: 1 page(s) / 7K

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NumLock status of a primary keyboard and NumLock status of a keypad are synchronized, which causes usability problems. In case that the primary keyboard is a laptop keyboard or a space saver keyboard which has no separate numeric section but an embedded numeric keypad on the alphanumeric section, numeric inputs from a keypad require for the system side to be at the "NumLock On"status, which automatically forces the NumLock status of the primary keyboard to be the "NumLock On"status. Whenever users go back to inputs at the alphanumeric section of the primary keyboard, the users need to cancel the NumLock On status of the embedded numeric keypad with depressing the Shift and ScrollLock keys, or the NumLock key on the keypad. This invention is to resolve the problem with adding mechanical switch to set initial NumLock status to be reversed or synchronized, and with controlling the reverse and the synchronization with scan code emulation by keypad firmware. The invention has advantages of no extra driver program required on the system side for controlling the NumLock status, no EEPROM required on the keypad microcontroller to store the initial NumLock mode, and no complicated firmware required on the keypad.

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Numeric keypad NumLock status management

1. Implementation of Invention Numeric keypads have NumLock On and Off modes in the firmware to be toggled by the NumLock key depression. The NumLock modes of the keypad do not affect NumLock status of the primary keyboard as the keypad is designed not to send the NumLock scan code to the system when the NumLock key is depressed. The keypad has an extra hardware change-over switch to set the initial NumLock mode, which can be synchronized with or reversed against the NumLock status of the primary keyboard. In case of laptop keyboards or space saver keyboards used as a primary keyboard, the initial NumLock mode should be set to the reverse so that the embedded numeric keypad of the primary keyboard is disabled and the external keypad is in the NumLock mode.
2. Key Depression Handling The keypad is to send the NumLock code before and after a keypad key code when the keypad is in the NumLock On mode so that the NumLock status of the primary keyboard is changed only for a sufficiently short period of the keypad key code transmission, and recovered to the original NumLock status. The keypad is to send only a key code when the keypad is in the NumLock Off mode. The initial NumLock mode can be set with an extra hardware change-over switch. The NumLock mode can be changed with a NumLock key depression of the keypad. The NumLock key depression does not send NumLock codes to the system side.
3. Scan Code Output A procedure to send ke...