Printer
AssigneeTokyo Shibaura Denki Kabushiki Kaisha
InventorSakuyuki Mizuno
Life of this patent
Estimating the term…
Abstract
A sampled input video signal is supplied to first and second comparators respectively having high and low reference levels, and the outputs of the first and second comparators are checked with each other in synchronism to the timing of the sampling. If the outputs of the first and second comparators are both detected, a thick black dot is printed. If only the output of the second comparator is detected, the pulse duration of a drive pulse output supplied to a printing head is reduced, so that a thin gray dot is printed.
Claims11
Apparatus for printing data contained in an input video signal asynchronously of said input video signal comprising:
- means for generating a sampling clock signal independently of said input video signal;
- means for sampling said input video signal with said sampling clock signal;
- first comparator means for providing a first pulse output when the level of the sampled input video signal is higher than a first reference level;
- second comparator means for providing a second pulse output when the level of the sampled input video signal is higher than a second reference level which is lower than the first reference level;
- means for separately memorizing the pulse outputs of said first and second comparator means;
- means for reading out said first and second comparator means pulse outputs stored separately in said memorizing means and checking them with each other for each sampling;
- and
- means for printing a regular thick black dot when said first and second comparator means pulse outputs are detected as a result of the checking and printing a thin gray dot when only the second comparator means pulse output is detected on a printing sheet.
Apparatus according to claaim 1, which further comprises first and second high-pass filters respectively connected between the output side of said first and second comparator means and input side of said memorizing means.
A printer comprising:
- means for sampling an input video signal;
- first comparator means for providing a first pulse output when the level of the sampled input video signal is higher than a first reference level;
- second comparator means for providing a second pulse output when the level of the sampled input video signal is higher than a second reference level which is lower than the first reference level;
- a first shift register for successively storing said first comparator means pulse output;
- a second shift register for successively storing said second comparator means pulse output;
- first and second memories for storing said respective first and second comparator means pulse outputs stored in said first and second registers;
- write control means for controlling the writing of said first and second comparator means pulse outputs stored in said first and second shift registers into said first and second memories, said write control means including a printing synchronizing circuit section for providing a write signal for every slot group consisting of a predetermined number of slots in the horizontal scanning direction of a CRT display screen, and an address counter specifying the address of said memories according to said write signal;
- and
- means for reading out said first and second comparator means pulse outputs stored in said first and second memories and checking them with each other for each sampling;
- and means for printing a regular thick black dot when said first and second comparator means pulse outputs are detected as a result of the checking and printing a thin gray dot when only the second comparator means pulse output is detected on a printing sheet.
Dependencies are inferred from the claim text.