Pointer measuring device
A pointer measuring device (formerly called pointer instrument ) is a measuring device that uses one or more pointers to display measured values using a scale . It is almost exclusively an analog measuring device . The best- known example is the pointer clock for measuring time.
On the other hand, station clocks with a minute hand but without a second hand are digital measuring devices with the typical characteristic that details cannot be resolved in one step. (Steps in the second hand of a wristwatch change too quickly for anything else to be read from a continuously rotating hand).
The pointer can be movable in front of a fixed scale or fixed in front of a movable scale. Both can also be formed by light projection (enlarged illustration of the scale and light pointer ). See also mirror galvanometer .
Examples of pointer measuring devices
- Compass with magnetic needle, showing gyrocompasses
- Bimetal thermometers , liquid thermometers
- Hair hygrometer
- Can barometer
- Eddy current tachometers and tachometer displays in motor vehicles
- Ammeter , voltmeter , so far as moving-coil or moving iron operated
- fully mechanical scales
- in motor vehicles:
- Speedometer
- Tachometer
- Fuel gauge
- Coolant temperature display
- Time-synchronized pointer measuring device
Alternatives to the pointer measuring device are measuring devices that output their information through a
- Display in the form of a numeric display
- any physical quantity as a measurement signal , e.g. B. Standard signal in automation technology
- Representation on a data carrier for later evaluation or for documentation of process sequences
Advantages disadvantages
The advantage of pointer measuring devices lies in their readability "at a glance", that is, the measured value and its tendency to change can be recognized immediately.
Disadvantages are inaccuracies in the numerical reading, which can be reduced by a mirror scale or a light pointer, but cannot achieve the resolution of a multi-digit display.
In the case of the indicating devices, measuring devices with a scale display are preferred because of their greater clarity or measuring devices with numeric display because of their easier numerical readability, depending on the requirements. Some digital multimeters have both in their liquid crystal display: In addition to the numerical display, a bar graph display.