# US 4,399,468 A · Printer > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,399,468 A - Document ID: US4399468A - Status: Granted - Kind: A - Application number: 06/274,796 - Filed: 1981-06-18 - Granted: 1983-08-16 - Earliest claimed: 1980-06-25 - Assignees: Tokyo Shibaura Denki Kabushiki Kaisha - Inventors: Sakuyuki Mizuno - Web page: https://patentgrep.com/patent/US4399468A ## CPC - H04N 1/00: Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof - G06K 15/10: by matrix printers {(G06K15/028 takes precedence)} - H04N 1/4056: {the pattern varying in one dimension only, e.g. dash length, pulse width modulation [PWM]} - G06K 2215/0091: Outputting only video data, e.g. Hard copy of CRT display - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - G06K: GRAPHICAL DATA READING (image or video recognition or understanding G06V); PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS ## 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. ## Claims ### Claim 1 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. ### Claim 2 (depends on 1) Apparatus according to claim 1, wherein said memorizing means includes 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, and 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. ### Claim 3 (depends on 2) Apparatus according to claim 2, wherein said write control means includes 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. ### Claim 4 (depends on 3) Apparatus according to claim 3, wherein said printing synchronization circuit section includes an up/down counter with a predetermined numerical value preset therein, a slot counter for counting clock signal pulses corresponding to respective slots on the horizontal scanning line, a numerical value generator for always providing a predetermined numerical value signal, an addition circuit for adding the outputs of said slot counter and numerical value generator, a comparator circuit for comparing the output of said addition circuit and up/down counter, a block counter for counting coincidence outputs of said comparator circuit, means for supplying said coincidence output as said write signal to said address counter, and means for supplying a carry signal from said block counter as a reset signal to said address counter. ### Claim 5 (depends on 3) Apparatus according to claim 3, wherein said checking means each includes a plurality of exclusive OR gates having first and second input terminals to which the outputs of said first and second memories are coupled, a plurality of NAND circuits each having one input terminal to which the output of the corresponding one of said exclusive OR gates is coupled, means for supplying a first gate signal having a predetermined short duration to the other input terminal of each of said plurality of NAND circuits, a plurality of AND circuits each having one input terminal to which the output of the corresponding one of said NAND circuits is coupled, means for supplying a second gate signal having a predetermined long duration to the other input terminal of each of said plurality of AND circuits, and means for coupling the outputs of said plurality of AND circuits to said printing means. ### Claim 6 (depends on 5) Apparatus according to claim 5, wherein said means for supplying said second gate signal having a long duration includes an OR circuit having a plurality of input terminals to which the output of said second memory is coupled, and also wherein said means for supplying said first gate signal having a short duration includes a one-shot circuit to which the output of said OR circuit is coupled. ### Claim 7 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. ### Claim 8 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. ### Claim 9 (depends on 8) A printer according to claim 8, wherein said printing synchronization circuit section includes; an up/down counter with a predetermined numerical value preset therein; a slot counter for counting clock signal pulses corresponding to respective slots on the horizontal scanning line; a numerical value generator for always providing a predetermined numerical value signal; an addition circuit for adding the outputs of said slot counter and numerical value generator; a comparator circuit for comparing the output of said addition circuit and up/down counter; a block counter for counting coincidence outputs of said comparator circuit; means for supplying said coincidence output as said write signal to said address counter; and means for supplying a carry signal from said block counter as a reset signal to said address counter. ### Claim 10 (depends on 8) A printer according to claim 8, wherein said checking means each includes; a plurality of exclusive OR gates having first and second input terminals to which the outputs of said first and second memories are coupled; a plurality of NAND circuits each having one input terminal to which the output of the corresponding one of said exclusive OR gates is coupled; means for supplying a first gate signal having a predetermined short duration to the other input terminal of each of said plurality of NAND circuits; a plurality of AND circuits each having one input terminal to which the output of the corresponding one of said NAND circuits is coupled; means for supplying a second gate signal having a predetermined long duration to the other input terminal of each of said plurality of AND circuits; and means for coupling the outputs of said plurality of AND circuits to said printing means. ### Claim 11 (depends on 10) A printer according to claim 10, wherein: said means for supplying said second gate signal having a long duration includes an OR circuit having a plurality of input terminals to which the output of said second memory is coupled; and said means for supplying said first gate signal having a short duration includes a one-shot circuit to which the output of said OR circuit is coupled.