Photoelectric encoder, it is a kind of through the photoelectric conversion of the output shaft mechanical geometry convert pulse or digital displacement sensor. Is this item

Before application of most sensors, photoelectric encoder is composed of grating plate and photoelectric detection device. Grating plate is equal to a certain diameter of circular plate

To open a number of rectangular hole. By coaxial light code disc and motor, motor rotates, grating plate with motor rotate speed, the hair

Composed of electronic components such as photodiode detection device output number of pulse signal, its principle diagram is shown in figure 1; By calculating the light per second

The number of electric encoder output pulse can reflect current of motor speed. In addition, to judge the direction of rotation, the encoder can also provide the phase difference

90 o two pulse signals.

According to the principle of detection, can be divided into optical encoder type, magnetic type, inductive and capacitive. According to the calibration method and the mode of its output signal, can be divided into

For incremental and absolute type and hybrid 3 kinds.

(a) incremental encoder

Incremental encoder is directly using the principle of photoelectric conversion output three square wave pulse phase A, B and Z; A, B two groups of pulse phase difference of 90 o, it can be

Easy to judge the direction of rotation, and Z phase for each turn a pulse, for reference point positioning. It has the advantage of simple principle structure, mechanical average

Life can be in the tens of thousands of hours above, strong anti-jamming capability, high reliability, suitable for long distance transport. The downside is unable to output shaft rotation

The location information.

(2) the absolute encoder

Absolute encoder is direct digital output of the sensor, on its round encoder, several concentric yards along the radial direction, each composed of pervious to light and

Opaque sector and white composition, adjacent code number of sectors is double, the code number on the encoder is its binary digital bits

Number, in the side of the encoder is a light source, the other side corresponding to every yard a photosensitive element; When the encoder is in different position, the photosensitive element

According to the light or not proper level signal conversion, form a binary number. The characteristics of the encoder is don't counter in arbitrary rotation

Location can be read out a fixed position and the corresponding digital code. Obviously, the more code word, the higher the resolution, has N for a bit

Binary resolution of the encoder, the encoder must have N barcode. The current domestic existing 16-bit absolute encoder products.

Absolute encoder are using natural binary or circulation binary (gray code) way of photoelectric conversion. Absolute encoder and incremental

Encoder differed from the disk in pervious to light, opaque line graphics, absolute encoder can have several coding, according to the reading on the encoder

Code, detecting absolute position. The design of the code can use binary code, cyclic code, two's complement, etc. Its features are:

1. You can direct the absolute value of the Angle coordinate;

2. No cumulative error;

3. Power source location information will not be lost after resection. But the resolution is determined by the binary digits, which means accuracy depends on the figures,

At present, 10, 14, etc.

(3) hybrid absolute value encoder

Hybrid absolute encoder, it outputs two sets of information: a set of information to detect magnetic pole position, with absolute information function; After another group

Output information of the whole with incremental encoder.

Photoelectric encoder is a kind of Angle detection device (angular velocity), it will be input to the shaft Angle, using the principle of photoelectric conversion is transformed into the corresponding

Electrical pulses or digital quantity, small size, high precision, reliable operation, the advantages of digital interface. It is widely used in nc machine tools and rotary table

, servo drive and determination of robot, radar, military, etc need to detect Angle of plant and equipment.