| 摘要 |
<p>An optical display is provided to guide the operator of a metering device during the metering of a substance to a desired value. The desired value is entered into a computer and the substance to be metered is applied to a balance. The display is an analog display in the form of a clock face having a coarse and a fine indicator hand or hands. During the coarse metering phase occurring at the start of the metering cycle, the coarse metering hand is rotated at a first rotational speed which is relative to the metering rate, i.e., the rate at which the substance is being applied to the balance. During the fine metering phase, namely when the weight on the balance approaches the desired weight, either the same or another hand moves at a rotational speed which is relative to the metering rate but which exceeds the first rotational speed, thereby expanding the sector over which the hand moves while a given amount of the substance is being applied. This greatly facilitates the operator's control over the process and decreases the possibilities that excess weight is added, since it provides an optimum, unequivocal indication to the operator of the actual weight on the scale during the metering process.</p> |
