Let you know more about encoder

Let's start with the encoder classification.Encoders can be categorized in the following ways:

Different types of holes in the coals

(1)incremental:it's a pulse signal per unit of rotation(also with a positive cosine signal,

Then carries on the segmentation,chopping frequency higher pulse),usually as A,B phase output,Z,A,B phase for each delay 1/4 cycle of pulse output,according to the relationship can be the difference between positive and negative transfer delay,and by taking A,B phase of rise and fall along the frequency can be 2 or 4 times;Z is a single loop pulse,which is a pulse per circle.

(2)the absolute value type:is corresponding to a circle,the Angle of each datum from a unique Angle and the corresponding binary value,through the external memory circle device can record and measure of multiple locations.

The output type of the signal is divided into:voltage output,collector open circuit output,push-pull complementary output and long line drive output.

3,classification by encoder mechanical installation form

(1)there are shafts:there are shafts,which can be divided into clamping flanges,synchronous flanges and servo installer.

(2)shaft type:the axial type can be divided into semi-empty type,full air type and large-caliber type.

The working principle of coder is divided into:photoelectric,magnetic and contacts.

The main function of encoder

It is a rotating displacement is converted into a string of rotary sensor of digital pulse signal,these pulses can be used to control the angular displacement,if encoder with the gears or helical screw together,can also be used to measure the linear displacement.

The encoder generates electrical signals and is controlled by several controlled CNC,programmable logic controller PLC and control system.These sensors are mainly used in the following areas:machine tool,material processing,motor feedback system and measurement and control equipment.The transformation of angular displacement in ELTRA encoder USES photoelectric scanning principle.The reading system is based on the rotation of the radial disc,which is made up of alternating light and opaque Windows.All the system using an infrared light source vertical irradiation,so light is put the plates on the image projected onto a receiver on the surface,the receiver is covered with a layer of grating,known as the collimator,it has the same window and cd-rom.The receiver's job is to feel the changes in the light produced by the rotation of the disc,and then convert the light changes to the corresponding electrical changes.In general,the spin encoder also gets a speed signal,which is fed to the frequency converter,which adjusts the output of the frequency converter.Fault phenomena:1,the rotary encoder bad(not the output),inverter can't work normally,becomes slow,and in a short while inverter protection,display"PG"...Joint action will work.To increase the electrical signal to a higher level and produce a square wave pulse without any interference,it must be processed by an electronic circuit.The connection between the encoder pg and the parameter vector inverter and the encoder pg must correspond to the type of the encoder pg.In general,the encoder pg type differential output,open collector output and push-pull output three,the signal transmission way must consider the frequency converter of pg card interface,so choose the appropriate pg card type or set reasonable.Generally divided into incremental encoder and absolute,they save the biggest difference:in the case of incremental encoder,starting from zero position mark determine the number of pulses,and the position of the absolute encoder is set by output code reading.In a loop,the output code for each location is unique;Therefore,when the power is disconnected,the absolute coder does not separate from the actual location.If the power is connected again,the position reading is still current and valid.Unlike an incremental encoder,you must look for a zero mark.

Encoder manufacturers production series is very complete,are generally not dedicated,such as the elevator special encoder,encoder for machine tool,a special servo motor encoder,etc.,are intelligent and encoder,there are all sorts of parallel interface can communicate with other devices.

A device that converts angular displacement or linear displacement into electrical signals.The former become the encoder,the latter said yardstick.According to the readout method encoder can be divided into two kinds of contact type and non-contact.Contact output,using brush a brush contact conductive area or insulation area to represent the state of the code is"1"or"0".Acceptance of non-contact sensor is photosensitive components or magnetic sensor,using photosensitive element to pervious to light and opaque to represent the state of the code is"1"or"0".

According to the working principle encoder can be divided into incremental and absolute type.The incremental encoder converts the displacement to a periodic electrical signal and converts the electrical signal into a counting pulse,indicating the size of the displacement in terms of the number of pulses.Absolute encoder type of each location corresponding to a certain numerical code,so it's only with the measurement value for start and stop position,and has nothing to do with the measurement in the middle of the process.

Rotating to turn the output pulse incremental encoder,through counting device to know its position,when the encoder or power failure,rely on counting device's internal memory to remember the location.So,after the power outage,there cannot be any movement,encoder when calls work,in the process of the encoder output pulse,also can't be a pulse interference and loss,otherwise,the counting device memory of zero offset,and the amount of the offset is don't know,can only know wrong after the production results.The solution is to increase the reference point,and the encoder will revise the memory location of the counting device for each reference point.There is no guarantee of location accuracy before reference points.To do this,we have to find a reference point for each operation in the factory,and then turn on the change.Such coders are determined by the mechanical position of the coder,which is not affected by power failure or interference.

Absolute encoder is determined by mechanical position of the uniqueness of each position,it does not need memory,don't need to find a reference point,and don't always count,when you need to know,when to go to read it.In this way,the anti-interference characteristics of the encoder and the reliability of the data are greatly improved.

Because the absolute encoder is clearly superior to the incremental encoder in locating,it is increasingly used in the position of industrial control.

The development of the encoder

From the industry,the elevator,machine tool and servo motor are the key applications of the encoder,accounting for 53%of the market share of the overall application market.Textile machinery,packaging machinery,printing machinery in areas such as market share is small,the encoder is generally not directly into the three industries,encoder manufacturers competition focused on for the machinery industry to provide the motor of the servo motor manufacturer.The share of the machinery market is also small,at just 4 to 5 per cent.In projects such as metallurgy and electronics,the proportion of coders is low,accounting for only 14%of market share.In addition,the encoder in medical machinery,wind power,auto production line,hybrid cars,water conservancy,rail transportation and other fields have some application,but the application rate is low.

Wind power industry automation products demand growth in 2010 reached more than 50%,while the elevator,servo motor,main application field of textile machinery and machine tools such as encoder growth is more obvious,is the main source of growth.

From the point of manufacturers,the European and American brands to occupy the high-end market,accounting for more than one-third of the market share,product price positioning high-end,has advantages in the field of heavy industry,and wind power and other new energy;Japan and South Korea brand occupy the mid-market,mainly also accounted for more than a third of the market share,product price positioning in the end,in the elevator,machine tools,servo motor has been widely applied in industries such as;Mainland companies,which are mainly involved in low and medium market competition,have low prices,which account for just 25 per cent of the market in the mainland market.

Companies with high market share include Heidenhain,Tamagawa,Nemicon,Yuheng,Baumer,Rep,P+F,Danaher,Koyo,Omron,etc.The top three enterprises in the market share accounted for nearly 50%of the total amount of the market,market concentration is higher,the enterprise mainly aims at the application of industry concentration is higher,the less competition in the industry.There was also a clear gap in the growth of mainstream manufacturers,with the largest increase of 60 per cent,with the smallest increase of less than 10 percent.

The encoder is divided into absolute value and incremental.Price of absolute encoder is about four times bigger than the incremental encoder,70%of the domestic market is the price of relative economic incremental encoder,mainly used in industries such as packaging,textile,elevator only demands speed and the absolute position measurement equipment is not high.In high precision mechanical equipment or steel,port and lifting heavy industry such as industry,due to the relatively high accuracy of measurement,more information will use absolute value encoder.In these heavy industry applications,due to the bad condition,the indexes of the anti-shock and vibration of the coder are higher.

With the improvement of mechanical equipment automation,application field of the encoder products also more and more widely,the customer is no longer satisfied with the rotation of the encoder can only physical signal is converted to electrical signals,and also requires the encoder more integrated,more durable products,and hope to be able to appear in the absolute value encoder richer interface mode,make more equipment intellectualization.

Production safety throughout the industrial market and communication security is more and more attention of national level began to product safety performance of the request,the encoder in the aspect of safety standards have corresponding specification,but due to the domestic market of encoder relatively low technical requirements for products,customers more favor of low-end products.