ENGLISH
日本語
Welcome to the CUI Devices Product Spotlight on panel mount encoders. Learn about CUI Devices' C14 and ACZ panel mount encoder series, including their applications, specifications and the available products in CUI Devices' broad line of encoders.
There are many types of encoders. In this product spotlight we will focus on rotary encoders. Rotary encoders can be defined as transducers designed to turn a rotational displacement into an electrical signal which can be read by a microprocessor.
Panel mount encoders are a type of rotary encoder. They are primarily used for human interface purposes, i.e., a volume knob on a stereo. They give the user the ability to control various system parameters by providing the link between the user and the system processor.
Panel mount rotary encoders are rapidly gaining popularity over potentiometers which are the other, major panel mount components used to translate rotational movement into a readable signal. The first advantage that encoders offer over potentiometers is consistency. Potentiometer manufacturing tolerances are large, leading to inconsistencies between units in the same batch. Accuracy is tied to consistency. Secondly, digital outputs are more compatible with today's digital devices and require no analog to digital converters, reducing cost and preventing errors.
Panel mount encoders are used in many applications across numerous industries, including defense & aerospace, medical, consumer goods, and test & measurement to name a few
Defense & Aerospace
|
 |
Rescue & Security
|
 |
Light & Sound
|
 |
Infrastructure Control
|
 |
Research & Science
|
 |
Industrial Automation
|
 |
Transportation Vehichle
|
 |
Building & Facilities
|
 |
Consumer
|
 |
Medical
|
 |
There are several key specifications to consider when talking about rotary encoders. PPR (pulses per revolution) determines the encoder's resolution, which is defined as the number of square wave pulses per 360 degree rotation of the encoder. Additionally, we define PPR as the number of low to high transitions per channel per revolution. Occasionally, an encoder's resolution is specified as CPR (counts per revolution), which is simply the number of quadrature state changes per revolution, CPR= PPR x 4.
Detents are useful in providing feedback to the user by "clicking" into place as the shaft is rotated. Detents are specified as the number of clicks per 360 degree rotation.
The push switch feature simply provides another user input signal. It is often used to select the function to be manipulated by turning the encoder knob.
CUI Devices' rotary encoders output a square wave signal. The signal is comprised of a series of pulses, which are defined as one full square wave cycle, or a transition from low to high back to low, or high to low back to high. Simply stated, a pulse is a measure of the waveform from one identical point to the next.
CUI Devices' rotary encoders utilize square waves with two channels that are offset 90 electrical degrees from each other. By detecting which channel is leading the other, direction can be monitored.
Most applications will use quadrature state changes to increase the counts per revolution. Increasing the counts per revolution increases the effective resolution of the encoder. In this case, one cycle is a transition from low to high back to low on both channels.
Microcontrollers use different methods for counting:
Most panel mount encoders need to be connected to a microcontroller that can source current. The microcontroller provides a path to V+ and the encoder provides a path to ground creating a complete circuit. Another term commonly used for sinks is "open collector." This means the collector of the output transistor is external to the unit.
Mechanical encoders are less expensive and can handle a wider range of voltages. However, they require de-bounce circuitry to produce a clean signal and have a shorter life cycle. Optical encoders, on the other hand, are typically more expensive but have a higher life cycle and provide a cleaner output signal that does not require de-bounce circuitry. Additionally, for precision applications, optical encoders can provide higher resolutions.
Mechanical
|
 |
Optical
|
 |
Optical encoders are made up of three basic parts: a light source, a light detector, and a code wheel. The source shines light through slits in the code wheel and the detector senses this light. The code wheel has evenly spaced slits which transmit and alternately block the light source. Internal circuitry enables and disables an output depending on whether or not the light is being detected or blocked.
Mechanical encoders are essentially a series of switches. The code wheel contains contacts spaced evenly along its outer edge. Another contact is stationary and mounted on the encoder chassis. As the code wheel turns it makes, then breaks, contact with the code wheel contacts, one at a time. This making and breaking of a circuit generates a voltage pulse which can be read by a microcontroller.
In a perfect world, a switch is characterized by having two states, on and off. Unfortunately, in the real world, switches can hover or bounce between the two states, creating a distorted signal. Switch bounce can be incorrectly read as additional pulses by a microcontroller. To prevent this debounce, circuitry is used to "square up" the output. Because mechanical encoders are essentially a series of mechanical switches, they require debounce circuitry and programming to ensure that the output can be used.
The C14 optical encoder series holds some advantages when compared to other optical encoders on the market. It is compact, measuring 15 mm across. The body and shaft feature metal construction, creating a rugged package that can be further protected with the optional IP65 rating. The C14 outputs a crisp, clean square wave, making interpolation easier and more accurate for the microprocessor. Finally, with a rotational and push button life of 1 million cycles, the C14 is built to last.
The series is available in 30 configurations. Some of the key options include 16 and 32 pulses per revolution, configurations with and without push button, with and without detent, multiple shaft styles, and three different mounting orientations.
The ACZ mechanical encoder series is available in 40+ configurations. Some of the key options include various resolutions, configurations with and without push button, with and without detent, multiple shaft styles, and two different PCB mounting orientations.
CUI Devices' ACZ and C14 Encoder series are designed to provide an accurate and inexpensive method for user input across a wide range of applications. The ACZ series utilizes mechanical encoder technology, offering a rugged, low cost solution. The C14 series on the other hand utilizes optical encoder technology, offering a clean signal and long life cycle for high precision applications. Overall, CUI Devices' wide range of options and features provides a reliable solution for virtually any customer need.
