Initializing method for printing type rings in printer

A method for operating a printer having printing type rings mounted to a first shaft for rotation in a first direction;

• a sensor disk mounted to a second shaft for rotation in a second direction opposite to said first direction;
• transfer gear means for coupling said first and second shafts for simultaneous rotation in opposite directions;
• hammer means for contacting said printing type rings and for effectuating printing of print types onto a paper;
• said sensor disk having formed thereon a series of detecting elements disposed over a first sector of said disk, said sector with said detecting elements defining an angle substantially less than 180.degree., said series of elements including a leading detecting element at the beginning of said series in the second direction, said leading element operative as an initial position detecting element, a trailing element at the end of said series in the second direction of rotation and a multiplicity of at least ten main detecting elements intermediate said leading element and trailing element, the remaining second sector between said trailing element and leading element having a space with no detecting elements and defining an angle of at least 180.degree.;
• said main detecting elements being equally spaced and corresponding in number to the number of printing types;
• said trailing detecting element being spaced from the last main detecting element in the second direction of rotation at a distant approximately two times that of the distance between adjacent main detecting elements;
• sensing means for detecting the passage of said detecting elements during rotation of said sensor disk and for generating a pulse signal in response to the passage of each element;
• characterized by the steps of continuously counting the number of pulses generated during the rotation of said sensor disk;
• measuring a minimum pulse interval between said pulses;
• further rotating said disc to generate pulses from said sensing means;
• determining that a pulse interval between said generated pulses is not greater than a value twice or more than said minimum pulse interval;
• establishing that said generated pulse signal after said determining step is a stop pulse produced in response to said trailing element, stopping said printing type rings at a predetermined position in response to said stop pulse.