How does a barcode scanner work?
Barcode scanning has spread all over our daily life, widely used in supermarkets, logistics couriers, libraries and other scanning goods, documents of the barcode. Today, we focus on what is bar code and how barcode scanners work.
What is a barcode scanner?
Barcode scanner, also known as barcode reader, barcode scanning gun, barcode scanner, barcode scanning gun and barcode reader. It is a reading device used to read the information contained in the barcode. Using the optical principle, the content of the barcode is decoded and transmitted to the computer or other equipment by data line or wireless way.
The structure of barcode scanner is usually divided into three parts: light source, receiving device, photoelectric conversion part, decoding circuit and computer interface.
The scanning gun is that the light emitted by the light source irradiates the barcode symbol through the optical system. The reflected light is imaged on the photoelectric converter by the optical system and interpreted by the decoder as a digital signal that can be directly accepted by the computer.
4 techniques used in barcode Scanner
Common barcode readers usually use the following four technologies: light pen, CCD, laser, image red light.
Pen-type reader principle:
Light pen is the first kind of hand-held contact barcode reader, it is also the most economical barcode reader.
When in use, the operator needs to contact the light pen to the barcode surface, through the light pen lens to emit a very small light point, when this light point from left to right across the barcode, in the "empty" part, the light is reflected, the "bar" part, the light will be absorbed, so in the light pen interior to produce a changing voltage, this voltage by amplifying, shaping for decoding.
CCD reader principle:
CCD is an electronic coupling device (Chargcoupledevice), is more suitable for close and contact reading, its price is not as expensive as laser readers, and there are no moving parts inside.
The CCD reader uses light from one or more LED, to cover the entire barcode, the image of the barcode is transmitted to a row of light, is sampled by each individual photodiode, and each bar or space is distinguished by the adjacent detection result as "black" or "white" to determine the character of the barcode. In other words, the CCD reader does not pay attention to reading each "bar" or "empty", but the entire part of the barcode. And converted into an electrical signal that can be decoded.
Laser scanner principle:
Laser scanners are relatively expensive among all kinds of scanners, but they can provide the highest functional indicators, so they are widely used in various industries.
The basic working principle of the laser scanner is that the hand-held laser scanner emits a beam of light through a laser diode, irradiates a rotating prism or a swinging mirror, and the reflected light shines through the reading window to the barcode surface. The light returns to the reader after a strip or empty reflection, which is collected and focused by a mirror and converted into an electrical signal by a photoelectric converter. The signal will be decoded by a scanner or decoding software on the terminal.
Laser scanner is divided into two forms: hand-held laser gun is convenient and simple to connect, flexible to use. Fixed laser scanner is suitable for reading the largest, barcode smaller occasions, effectively liberate the hands to work.
Image type red light principle :
The image type red light barcode reader is a barcode reader which can replace the laser gun! Its scanning depth of field is up to 30 cm, combined with its scanning speed of up to 300 times per second, so that it has excellent code reading performance. Unique image design, so that its decoding ability is very strong, the general scanner can not read the barcode, and the image red light can still be easily read. Through the intelligent interface, only need to replace the cable to realize the keyboard, RS232 serial port, USB and other interface conversion, at the same time, can also be directly connected to the notebook computer.