A phase comparator is disclosed that can provide a phase comparison result at high speed that essentially does not vary according a power source voltage, ambient temperature andor manufacturing process conditions, or the like. The tool is mounted to a computer and provides a user with the ability to align the computer display screen with their eye so that the user’s line of sight is perpendicular to the display screen, which is the optimal viewing angle for viewing a display screen. The pin is moveable through the opening between pre-driven and driven positions. In a second working position for draining the gearbox oil, an oil drain opening of the device is released, which opening is arranged below the upper opening and therefore permits draining of a large part of the oil disposed in the gearbox. Thereby, an ink cartridge providing amounting feeling and dispensing with a spring member for assisting detachment can be provided.