JPH0210631B2 - - Google Patents

Description

[Detailed Description of the Invention] (A) Technical Field of the Invention The present invention is applicable to electrostatic recording printers, electrophotographic printers, etc., which decompose printed information such as characters and figures into pixels and convert them into binary data for each pixel. The present invention relates to a printing device that converts signals into serial signals and prints in dots.

(B) Background of the technology Electrostatic recording printers and electrophotographic printers have excellent printing quality and printing speed, and can use a wide variety of character types.
It has functions such as enlarging, reducing, or transforming patterns such as figures, and printing has come to be performed in a variety of modes by applying these various functions. However, this tends to cause malfunctions, that is, abnormal printing, and therefore, it has become an important technical issue to be able to immediately detect such malfunctions.

(C) Prior art and problems Electrostatic recording printers or electrophotographic printers store input print information consisting of codes corresponding to individual characters, symbols, figures, etc. as codes (hereinafter referred to as codes). It is equipped with a buffer and a pattern memory that stores basic patterns such as characters and images as binary data in the form of dots, converts printing information into a serial binary video signal, and prints using a raster scanning method. Conventionally, an error detection circuit such as a parity check method has been provided to detect errors that occur in the exchange of various signals between the conversion circuit and the buffer or pattern memory.

However, no checks are performed on the binary video signal after the conversion, and therefore it is difficult to ensure that abnormal printing occurs due to the various print modes mentioned above. could not be detected.

(D) Purpose of the Invention The purpose of the present invention is to print by inserting test information into blank portions of input print information that are not printed (portions that become blank when printing), and to perform test printing without printing test information. By checking the conversion status of dot information for each pixel of information, it is possible to more reliably detect abnormal printing that occurs due to various print modes during service printing than before. .

(E) Structure of the Invention The video signal checking method of the printing apparatus according to the present invention includes a pattern memory that stores basic dot patterns corresponding to codes representing characters, symbols, and figures, and a pattern memory that stores basic dot patterns corresponding to codes representing characters, symbols, and figures; In an apparatus that performs printing by raster scanning, the apparatus includes a conversion circuit that reads out input print information corresponding to each code and converts it into dot information for each pixel, and the input print information is input corresponding to a printing area. an identification circuit that identifies test information based on a code replaced with a blank character portion of the printed information; a counter that counts the number of dots output by the conversion circuit in response to the test information; and a count value of the counter. A comparison circuit that compares a predetermined number of dots corresponding to the test information and a circuit that prohibits printing of the test information are provided, and the comparison circuit uses the test information included in the input print information in advance. The present invention is characterized in that it is checked whether the operations related to the pattern memory and the conversion circuit are normal or not based on the match/mismatch outputs.

(F) Examples of the invention Hereinafter, the gist of the present invention will be specifically explained using examples.

The figure shows a system block diagram of an embodiment of the present invention, in which 1 is a buffer that temporarily stores print information such as characters and figures in predetermined amounts using codes;
2 is a pattern memory that stores basic patterns such as characters and figures as binary data for each pixel; 3 is a pattern memory that reads out the basic patterns stored in pattern memory 2 according to print information stored in buffer 1 and converts them into binary video signals 4 is a table that stores the number of dots corresponding to the test information included in the print information; 5 is a conversion circuit that stores the number of dots corresponding to the test information included in the print information; An identification circuit for identifying the test information based on the replaced code; 6 is a gate for controlling the output of the conversion circuit 3 to prohibit printing other than a predetermined area on the printing paper; 7 is an identification circuit for identifying the test information included in the print information; a first AND circuit that inputs only the binary video signal outputted from the conversion circuit 3 to a counter described later;
and 9 constitute a circuit that prohibits printing of test information, 8 is a NOT circuit that inverts the output of the identification circuit 5,
9 is a second AND circuit that inputs only the binary video signal output by the conversion circuit 3 corresponding to the print information excluding test information to the laser output circuit described later; a laser output circuit that modulates and outputs a laser beam; 11 is a counter that counts the number of "1"s indicating dots in the binary video signal output by the first AND circuit 7;
A comparison circuit 12 compares the count value of the counter 11 and the number of dots stored in the table 4.

That is, appropriate test information is inserted in advance into a blank area after one line in the input print information or a blank area of a document that is not printed, and the conversion circuit 3 is supposed to output according to this test information. The number of "1"s, that is, the number of dots, in the binary video signal is stored in advance in the table 4, and based on this value and the test information, the number of "1"s in the binary video signal actually output by the conversion circuit 3 is stored in the table 4. '' is used to detect abnormal printing.

(G) Effects of the Invention As explained above, according to the present invention, test information is inserted and printed in blank areas where input print information is not printed, and test information is printed without printing test information. By checking the conversion status of dot information for each pixel, abnormal printing can be detected more reliably than before during execution of service printing, and the reliability of the printing apparatus can be improved.

[Brief explanation of drawings]

The figure shows a system block diagram of an embodiment of the present invention, in which 2 is a pattern memory, 3 is a conversion circuit, 5 is an identification circuit, 11 is a counter, 12 is a comparison circuit, and 8 and 9 are for printing test information. This is a prohibited circuit.

Claims (1)

[Claims] 1. A pattern memory that stores basic dot patterns corresponding to codes representing characters, symbols, and figures; and a pattern memory that stores basic dot patterns corresponding to codes representing characters, symbols, and figures; A conversion circuit for reading out and converting into dot information for each pixel, and in an apparatus for printing by raster scanning, wherein blank character portions of the input printing information given corresponding to the printing area are replaced. an identification circuit that identifies test information based on a code; a counter that counts the number of dots output by the conversion circuit in response to the test information; and a predetermined number of dots that corresponds to the count value of the counter and the test information. and a circuit for prohibiting printing of the test information, and using the test information included in the input print information in advance, the pattern memory and the A video signal check method for a printing device characterized by checking whether or not the operation related to a conversion circuit is normal.