Barcode encyclopedia : Symbology telepen
Telepen barcode symbology.
- Devised by George Sims, Chairman of SB Electronic
- Only symbology to directly represent the full ASCII character set without shift characters
- Double density numeric mode
- Very compact.8 ASCII characters or 16 digits per inch
- Easy to print. Fixes3:1 ratio. Tolerance at least 0.4x.
- Extremely secure.
- Supported by most leading manufacturers.
History and descriptionDeveloped in year 1971. Computer technology had developed very rapidly, data identificantion must be very easy and successfull.Point of sale - motivation in year 1972 to develop hand help black and white bar code system.
British and American company were also working along these lines, this was known and it therefore necessary to device symbology:
The perceived requirements were as follows:
- Representation of full ASCII character set
- Space required should not exceeded twice that for human readable printing
- Possible to produce on conventional printers
- Very high security
- All characters should take up the same amount of space
The length of the code for a given number of chracters clearly should not vary with the data.Adjusting the widths of the bars within a character to archieve this is also not acceptable.
A wide to narrow bar ratio of 3:1 is implied. These are four possible combinations of wide and narrow bars and spaces. Binary 1, 00, 010, 01/10.
A binary string may now be extremely efficiently encoded. Exactly twice sa Plessey code. Altrough multi-width symbologies as ANN or Code128 appear to have good packaking densites, very much tighter tolerances are required,. Reading is also, of course, more difficult.
Two levels of Telepen
- 8-bit even parity characters encoded least significant bit first, as with serial data transmission.
- Data character with the start code, data bits, checksum and stop code and checksum are formatted into complete symbol.
- A wide to narrow ratio of 3:1 isimplied, 2:1 does not allow sufficient margis print tolerances.
- Symbol is very secure, nomirror image problem.
- For numeric-only applications is used compression, two digits ore compressed to into one char, density is 5 aplha character or 10 digits per inch.
Maximum recommended density over 16 digit pre inch is archievable
- Implemented in many countries, very widely in United Kingdom.
- Most universites and other academic libraries use Telepen
- In public libaries
- In motor industrie, Ministry of Defence ...
The block check character is modulo 127.