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Barcode history
1. The history of barcodes
Barcode technology was first produced in the twitchy 1920s in the Westinghouse laboratory. An eccentric inventor named John Kermode “whimsically†wanted to automatically sort postal documents. At that time, every idea of ​​the application of electronic technology was very novel.
His idea is to make a barcode mark on the envelope. The information in the barcode is the address of the recipient, just like today's zip code. For this reason, Comand invented the earliest barcode identification, the design scheme is very simple (Note: this method is called the module comparison method), that is, one "bar" represents the number "1", and two "bars" represent the number "2" ", And so on. Then, he invented a barcode reading device consisting of basic components: a scanner (which can emit light and receive reflected light); a method for measuring reflected signal bars and voids, that is, edge positioning coils; and using the measurement results The method is the decoder.
Comand's scanner used a newly-invented photovoltaic cell to collect reflected light. The "empty" reflects a strong signal, and the "strip" reflects a weak signal. Unlike today's high-speed electronic component applications, Comand uses magnetic coils to measure "bars" and "empty". It's like a child connecting a wire to a battery and wrapping it around a nail to hold paper. Comand uses a coil with an iron core to attract a switch when it receives an "empty" signal, and releases the switch and closes the circuit when it receives a "strip" signal. Therefore, the earliest barcode readers were noisy. The switch is controlled by a series of relays. "On" and "Off" are determined by the number of "stripes" printed on the envelope. In this way, the barcode symbols directly sort the letters.
Soon after, Comand's collaborator Douglas Young made some improvements on the basis of Comand.
Comand code contains a relatively low amount of information, and it is difficult to compile more than ten different codes. Yang code uses fewer bars, but uses the change in the size of the spaces between the bars, just like today's UPC bar code symbols use four different bar sizes. The new bar code symbol can encode one hundred different regions in the same size space, while the Comand code can only encode ten different regions.
It was only for the first time in the patent literature in 1949 that there was a record of the full range of bar code symbols invented by Norm Woodland and Bernard Silver, in the previous patent literature There is no record of bar code technology and no precedent for practical application. The idea of ​​Noam Woodland and Bernard Silvo is to use the vertical "bars" and "empty" of Comand and Young and bend them into a ring, much like an archery target. In this way, the scanner can decode the bar code symbol by scanning the center of the graphic, regardless of the direction of the bar code symbol.
In the process of using this patented technology to constantly improve it, a science fiction writer Isaac Azimov (Isaac Azimov) in his book "The Naked Sun" (The Naked Sun) Examples of new methods of using information encoding to achieve automatic identification. At that time, people thought that the barcode symbol in this book looked like a checkerboard, but today's barcode professionals will immediately realize that this is a two-dimensional matrix barcode symbol. Although this bar code symbol has no direction, positioning and timing, it is clear that it represents a digital code with high information density.
It was not until Iterface Mechanisms developed the "two-dimensional code" in 1970 that there was a two-dimensional matrix bar code printing and reading device at a price suitable for sale. At that time, two-dimensional matrix barcodes were used to automate the newspaper publishing process. The two-dimensional matrix barcode is printed on the paper tape and scanned by today's one-dimensional CCD scanner. The light emitted by the CCD is on the paper tape, and each photocell is aimed at a different area of ​​the paper tape. Each photovoltaic cell outputs different patterns according to whether the bar code is printed on the paper tape, and a high-density information pattern is generated in combination. In this way, a single character can be printed on the same size space as a single bar in the early Comand code. Timing information is also included, so the whole process is reasonable. When the first system entered the market, the full set of equipment, including printing and reading equipment, cost about $ 5,000.
Soon afterwards, with the continuous development of LEDs (light emitting diodes), microprocessors and laser diodes, a new explosion of logos (symbolicology) and their applications was ushered in, which was called "barcode industry". Today it is rare to find companies or individuals who have no direct contact with fast and accurate barcode technology. Since the technological progress and development in this field are very rapid, and more and more application fields are being developed every day, it will not take long for bar codes to become as popular as light bulbs and semiconductor radios, which will make every one of us live. Have become more relaxed and convenient.