An incremental encoder is a device that converts displacement into periodic electrical signals, and then converts these signals into counting pulses, using the number of pulses to represent the magnitude of the displacement. Incremental encoders do not have a fixed starting zero point; their output is a pulse proportional to the increment of the rotation angle, requiring a counter to count the pulses.
Incremental encoders can be divided into two categories according to their readout method: contact and non-contact. Contact encoders use brushes for output, with the brush contacting the conductive or insulating area to indicate whether the code state is "1" or "0". Non-contact encoders use photosensitive or magnetic sensitive elements for receiving signals. When using photosensitive elements, the light-transmitting and opaque areas indicate whether the code state is "1" or "0".
Incremental encoders are mainly used in CNC machine tools and mechanical accessories, robots, automatic assembly machines, automatic production lines, elevators, textile machinery, sewing machinery, packaging machinery, printing machinery, woodworking machinery, plastic machinery, rubber and plastic machinery, drafting instruments, angle measuring instruments, radar and other fields.
Incremental encoder schematic diagram
As shown in Figure 4, the incremental encoder, like the absolute encoder, also has a code disk. An internal light source continuously illuminates the holes on the code disk, generating a pulse output each time the light passes through a hole for counting. Unlike the absolute encoder, the holes on the incremental encoder's code disk are all of the same size, and the encoder output has two signals, A and B, which are used to determine the encoder's forward and reverse rotation. When the phase of signal A leads the phase of signal B by 90 degrees, the encoder rotates forward; otherwise, when the phase of signal B leads the phase of signal A by 90 degrees, the encoder rotates in reverse.
What are the main electrical performance parameters of an incremental encoder?
Incremental encoders are commonly used position sensors for measuring rotary motion or linear position. They have some key electrical performance parameters, as described below:
1. Resolution:
Resolution refers to the number of position divisions per rotation cycle or per linear unit of the encoder. Higher resolution means that the encoder can provide more accurate position information.
2. Pulses per Revolution (PPR):
The pulse count represents the number of pulses generated in each encoder rotation cycle. The pulse count is usually directly related to the resolution and can be obtained by multiplying it by the number of rotation cycles.
3. Operating Voltage:
The operating voltage is the range of power supply voltages within which the encoder can operate normally. The encoder's operating voltage should be matched with the system's power supply voltage.
4. Output Signal Type:
Output signal type refers to the type of signal output by the encoder. Common output signal types include TTL, HTL, and Open Collector. These signal types differ in voltage level and interface.
5. Signal Period and Frequency:
The signal period refers to the duration of one complete cycle of the encoder pulse signal. Frequency refers to the number of pulses generated per second, which can be calculated by taking the reciprocal of the signal period.
6. Maximum Pulses per Second:
Maximum pulse rate indicates the maximum number of pulses the encoder can process per second. This parameter is related to the encoder's mechanical design and electronic control circuitry.
7. Output Current Capability:
Output current capability indicates the maximum load current of the encoder output signal. Ensure that the current capability meets the current requirements of the connected equipment.
These electrical performance parameters are key indicators for evaluating and selecting encoders based on their specifications and technical parameters. Depending on the specific application requirements, a suitable encoder needs to be selected to meet the system's performance requirements.
