JPH0210632B2 - - Google Patents

Description

[Detailed Description of the Invention] (A) Technical Field of the Invention The present invention relates to the printing of electrophotographic printers, electrostatic recording printers, etc. that separate patterns such as characters and images into pixels and print dots for each pixel. Regarding equipment.

(B) Background of the technology Electrophotographic printers or electrostatic recording printers, such as laser printers, have excellent printing quality and speed, and can use a wide variety of character types. It has functions such as transformation, and is therefore particularly suitable as an output device for computer systems for Japanese language processing, and these various functions are utilized to print in a variety of modes. However, along with this, not only partial dropouts of the print pattern, but also abnormal printing such as errors in the print mode and errors in the character pattern are likely to occur. Therefore, immediate detection of this is an important technical issue for the time being. It's summery.

(C) Prior Art and Problems Printing devices such as electrophotographic printers or electrostatic recording printers are equipped with a print control circuit and memories such as page buffers and character generators, and print information given by codes into dot patterns. Conventionally, these printing devices have been equipped with a parity check system or other error detection circuit to detect errors between the print control circuit and the memory. Errors that occur during the exchange of various signals were detected.

On the other hand, in the print control circuit, as mentioned above,
For example, enlarging/reducing and transforming character patterns,
In addition, printing has come to be controlled using various modes that combine these.
The error detection circuit has not been able to detect the abnormal printing that occurs under such control.

(D) Object of the Invention The object of the present invention is to solve the problems in the prior art described above, that is, to provide a means for detecting printing abnormalities caused by printing control in a printing control circuit.

(E) Structure of the Invention The printing device abnormal printing detection method according to the present invention comprises: a memory that stores a print pattern; a print control circuit that converts the print pattern stored in the memory into a binary video signal; and the print control circuit. and a gate control circuit that stores a non-printing area and controls the gate circuit to prohibit printing on the non-printing area. In the printing apparatus, a counter that counts the binary video signal of the abnormal printing detection pattern converted by the printing control circuit, and a verification circuit that matches the number of dots of the detection pattern with the counted value of the counter;
The print control circuit detects abnormal printing by converting the detection pattern into a binary video signal and outputting it corresponding to the non-printing area.

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

FIG. 1 is a block diagram of an embodiment in which the method for detecting printing abnormality in a printing apparatus according to the present invention is applied to a laser printer, and FIG. 2 is a diagram showing a printing area on printing paper.

As is well known, a laser printer implementing the method of the present invention prints a line with a predetermined number of dot lines by deflecting a laser beam modulated by a binary video signal using a rotating mirror or the like to raster scan a photosensitive drum. It is what is done.

Laser printers have a fixed scanning cycle for mirror scanning; for example, in a high-speed laser printer, the scanning cycle per dot line is 140 μs,
Of this, 100 μs is the actual printing period, and the remaining 40 μs is a blanking period area used for scanning outside the print area, blanking period, etc., and is not used for actual printing.

Furthermore, when printing on continuous paper, etc., the vicinity of the perforations between pages is a printing prohibited area, during which printing is not performed and only paper feeding is performed.

The present invention utilizes these flyback period areas and printing prohibited areas to process a predetermined print pattern for detecting abnormal printing, in which the number of dots during printing is known in advance, in a print control circuit and convert it into a binary video signal. An abnormality in the print control circuit is detected by outputting the output and comparing the count value of the output with the number of dots known in advance.

In Fig. 1, 1 is a memory called a line buffer that stores one line of print information sent from a print information recording medium in the form of a character code. It consists of a mode conversion specification, the address of the character pattern storage location in the character generator, etc. 2 calls the character pattern from the built-in character generator based on the character code for one line output from the memory 1, performs predetermined processing such as mode conversion, converts it into a binary video signal, and sends it to the gate circuit 3. This is a print control circuit that outputs output to the counter circuit 4 and the counter circuit 4. 3 is a gate circuit that turns on and off the output of the print control circuit 2; 4 is a laser output unit that modulates and outputs a laser beam according to the output signal of the gate circuit 3 to print in accordance with a video signal; 5;
6 is a gate control circuit that stores the blanking period area and the printing prohibited area and inhibits laser output during the period corresponding to the blanking period area and the printing prohibited area by controlling the gate circuit 3; 6 is a printing control circuit; A counter circuit 7 detects a predetermined printing pattern for detecting abnormal printing among the binary video signals outputted from 2 and counts the binary video signal corresponding to the pattern (for example, the mode has been converted in a predetermined manner). This is a verification circuit in which the number of dots of the predetermined printing pattern for abnormality detection stored in the memory 1 is set and this number of dots is compared with the count value of the counter 6.

The detection method of the present invention is performed using the circuit having the above configuration.

A code of a predetermined printing pattern for detecting abnormal printing is stored at the end of the line buffer memory 1, that is, at a portion corresponding to the blanking period area after the final character position of the line.

Every time you print the next line of character patterns,
Using the scanning period of the retrace period area at the end of the line,
The original pattern of the pattern for abnormal printing detection is set in the print control circuit 2, and a predetermined mode conversion is performed to make it into an actual printing pattern.2
The number of dots in the video signal of the value is counted by the counter 6, the counted value is input to the verification circuit 7, and the abnormality is detected by comparing it with the number of dots set in advance in the verification circuit 7 as a character code. Determine whether or not to print.

The printing pattern for abnormal printing detection is converted into a binary video signal in the printing control circuit 2 like other printing patterns, but it is gated in the gate circuit 3 and is not output to the laser output unit 4, so it is not printed. It never happens.

Figure 2 shows a character string 81 printed on printing paper 8.
This indicates a virtual position where a print pattern 82 for detecting abnormal printing is output, which is output from the printing control circuit but is gated by the gate circuit and not printed, and the number of dots is counted by the counter. The pattern is output and checked in a blank area such as a retrace period area at the end of a line, or in a period corresponding to a printing prohibited area near the perforation 83 in the case of continuous printing paper. The former allows you to check every line, but the software is complicated, while the latter allows you to check every page, but the software is simple.

Note that the address number of the character generator in which the abnormal printing detection pattern is stored may be set equal to the number of dots in the actual printing pattern after being processed by the printing control circuit. In this case, there is an advantage that checking is simple because it is only necessary to compare the counted actual printed pattern with the number of dots in the address.

(G) Effects of the Invention As explained above, according to the present invention, it is possible to detect abnormalities in printing that occur in the transmission and reception of various signals between the print control circuit and the memory, and in the various controls in the print control circuit. .

[Brief explanation of drawings]

FIG. 1 is a system block diagram of one embodiment of the present invention, and FIG. 2 is a diagram showing a printing area, where 1 is a memory, 2 is a print control circuit, 3 is a gate circuit, 5 is a gate control circuit, and 6 is a diagram showing a printing area. Counter, 7 is verification circuit, 8
81 is a printing paper, 81 is a printed character string, 82 is a printing pattern for detecting abnormal printing, and 83 is a perforation.

Claims (1)

[Claims] 1. A memory that stores a print pattern; a print control circuit that converts the print pattern stored in the memory into a binary video signal; a gate circuit provided after the print control circuit; a gate control circuit that stores a printing area and prohibits printing in the non-printing area by controlling the gate circuit, and performs dot-type printing by raster scanning, the printing control circuit a counter that counts the binary video signal of the abnormal printing detection pattern converted by the printing control circuit; and a verification circuit that compares the number of dots of the detection pattern with the counted value of the counter; A method for detecting abnormal printing in a printing apparatus, characterized in that abnormal printing is detected by converting the detection pattern into a binary video signal and outputting the detection pattern corresponding to a printing area.