Abstract: A head-mounted display may include a display system and an optical system in a housing. The display system may have displays that produce images. Positioners may be used to move the displays relative to the eye positions of a user's eyes. An adjustable optical system may include tunable lenses such as tunable cylindrical liquid crystal lenses. The displays may be viewed through the lenses when the user's eyes are at the eye positions. A sensor may be incorporated into the head-mounted display to measure refractive errors in the user's eyes. The sensor may include waveguides and volume holograms, and a camera for gathering light that has reflected from the retinas of the user's eyes. Viewing comfort may be enhanced by adjusting display positions relative to the eye positions and/or by adjusting lens settings based on the content being presented on the display and/or measured refractive errors.

Abstract: A spray malfunction detector system for electrostatic spraying apparatus having a sprayhead connectable to a high voltage source and for directing spray of charged particles of fluid towards an earthed target. The system comprises an earth circuit from the earthed target, a by-pass electrode located in the vicinity of the sprayhead and maintained in use at such a potential as to attract corona discharge from the sprayhead, and a current detector located in the earth circuit between the earthed target and any junction in the earth circuit and by which corona discharge joins the earth circuit from the by-pass electrode.

Abstract: A container having attached to it at least one memory device carrying information relating to the intended contents of the container; the device being operably connectable to apparatus responsive to information communicated from the memory device whereby an operation actively involving the contents of the container may be performed in a manner at least partly determined by the characteristics of the contents.

Abstract: A modular fluid spraying system including: at least one container for the fluid or fluids to be sprayed the container being fluid plug connectable to at least one fluid pumping which is in turn fluid plug connectable to at least one boom section, the boom section carrying fluid supply connections and being fluid plug connectable to other boom sections and to at least one sprayhead assembly detachably securable to the said boom section or sections; and at least one electronic data processing circuit electrically plug-connectable to the system and pre-set so as to regulate at least one electrically responsive operating parameter of the system when the system is connected to a source of electrical power in use; whereby various numbers of containers and/or various numbers of boom sections may be added or subtracted to the system to achieve a desired combination of fluid delivery and spray area.

Abstract: An agricultural chemical sprayer is disclosed using special pre-coded machine-readable chemical containers which, when attached for use, become an integral part of an automatic spray control system. The pre-coded data derived from a given container effectively prevents unauthorized and unsafe container refilling operations and, at the same time, automatically provides optimum control over the spray application rate (pump operation and/or electrostatic voltage), prevents mixing of incompatible spray solutions, prescribes proper spray system flushing procedures, and at all times after filling maintains an irreversible account of the available liquid remaining in the container. Provisions are made for monitoring the condition and/or operation of each spray nozzle and special connectors are provided for effecting optimum liquid and electrical circuit connections in such a system.