Abstract: A stylus or other tactile-based input device can receive different types of tactile input from a user. The tactile input sensing functions can be performed by a touch input sensor, such as a capacitive sensing device, and a compressive force sensor, such as a capacitive gap sensor. A touch input sensor can be integrated into an input device in a low profile form and overlap the compressive force sensor so that both touch input and compressive force input can be detected in the same regions of the stylus. Both types of tactile input can be received at the user's natural grip location.

Abstract: An illuminator may be coupled to the key cap of a key. The key cap may include a portion that is operable to be illuminated and one or more illuminators may be coupled thereto. In particular embodiments, keys may include power delivery systems that are operable to wirelessly transmit power from a power source to illuminators. Such power delivery systems can include inductive transmitters and/or receivers, ultrasonic transmitters and/or receivers, laser diodes and photodiodes, electrodes that capacitively couple to wirelessly transfer power, and so on. In various embodiments, keys may include interconnects that connect an illuminator with a power source. The interconnect may be a flexible material that includes one or more traces and is configured with a shape that bends and twists to allow movement without stretching. The interconnect may also be part of a movement or support mechanism of a key.

Abstract: A host electronic device may be coupled to an accessory electronic device. The host device and the accessory device may be connected via power supply lines and user data lines. If the host and accessory devices are improperly connected or if the accessory device is exposed to an incorrect voltage environment, the internal circuitry on the accessory device can be damaged. The accessory device may therefore include a reverse voltage protection circuit that can help prevent a large amount of current from inadvertently flowing into the accessory device. The protection circuit may include a low-side-enabled reverse current protection switch coupled between the external and internal ground terminals and also a single low-drop switch coupled to each of the user data lines. The low-drop switch will be activated whenever the voltage at the external ground terminal exceeds the voltage at the data line to help deactivate low-side-enabled reverse current protection switch.

Abstract: A host electronic device may be coupled to an accessory electronic device. The host device and the accessory device may be connected via power supply lines and user data lines. If the host and accessory devices are improperly connected or if the accessory device is exposed to an incorrect voltage environment, the internal circuitry on the accessory device can be damaged. The accessory device may therefore include a reverse voltage protection circuit that can help prevent a large amount of current from inadvertently flowing into the accessory device. The protection circuit may include a low-side-enabled reverse current protection switch coupled between the external and internal ground terminals and also a single low-drop switch coupled to each of the user data lines. The low-drop switch will be activated whenever the voltage at the external ground terminal exceeds the voltage at the data line to help deactivate low-side-enabled reverse current protection switch.

Abstract: An illuminator may be coupled to the key cap of a key. The key cap may include a portion that is operable to be illuminated and one or more illuminators may be coupled thereto. In particular embodiments, keys may include power delivery systems that are operable to wirelessly transmit power from a power source to illuminators. Such power delivery systems can include inductive transmitters and/or receivers, ultrasonic transmitters and/or receivers, laser diodes and photodiodes, electrodes that capacitively couple to wirelessly transfer power, and so on. In various embodiments, keys may include interconnects that connect an illuminator with a power source. The interconnect may be a flexible material that includes one or more traces and is configured with a shape that bends and twists to allow movement without stretching. The interconnect may also be part of a movement or support mechanism of a key.