JPH02215545A - Method of preventing temperature rise of printing head - Google Patents

Abstract

PURPOSE:To prevent overheating of a printing head without lowering a set temperature and to improve throughput of a printer by a method whereby the number of dots to be printed in a succeeding line is calculated, based on which the printing density of the succeeding line is operated and a printing method is selected in accordance with the high or low printing density. CONSTITUTION:In a detecting section of the printing density, an adder unit 6 calculates the number of printing dots in one line from printing data, and an adder unit 7 calculates the total number of dots in one line and feeds the same to an operating unit 8. The operating unit 8 obtains the printing density in one line. The obtained printing density is compared with a set value at a density comparing unit 9, so that the printing method is determined. When the printing density is low (Da), 'bidirectional printing' is selected. If the printing density is high (Db), 'unidirectional printing' is selected. Further, if the printing density is much higher (Dc), 'unidirectional printing and interline pause' is selected.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for preventing a print head temperature rise in a serial printer to prevent the print head from overheating.

(Prior art) Conventionally, when a printer is driven continuously, the print head generates heat, and especially in printers that use plungers, etc., there are drawbacks such as the magnetic flux decreases due to the heat generation and the impact force weakens. Ta.

Therefore, a device has been proposed that detects the temperature of the print head at multiple levels, for example, three levels, and prevents the print head from deteriorating and burning out due to overheating of the print head.
According to this method, based on the detection signal, high-speed printing is performed when the detected temperature is low, low-speed printing is performed when the detected temperature is high, and when the print head is overheated, It is designed to stop the printed text.

(Problem to be Solved by the Invention) However, in the print head temperature rise prevention method having the above configuration, when the print head temperature reaches a set temperature, the printing speed is reduced or the print body is stopped. Therefore, it is necessary to calculate the set temperature on the assumption that the print pattern with the largest temperature increase will be in the next line.

Furthermore, since a thermistor or the like is used as the temperature detection means, an error may occur between the actual temperature and the detected temperature. Therefore, the set temperature must be kept relatively low.

Furthermore, even if the print density of the next line of print patterns is low, when the print head reaches the set temperature, the printing speed decreases or printing is stopped, resulting in a problem that the throughput of the printer decreases.

The present invention solves the above-mentioned problems and provides a print head temperature rise prevention method that can prevent the print head from overheating without lowering the set temperature and increase the throughput of the printer. purpose.

(Means for Solving the Problems) For this purpose, the present invention enables the print head to select a printing method consisting of a plurality of printing states and a pause state each having a different printing load, and prints the print data to be printed in the next line. The number of dots is counted, the printing density of the next line is calculated from the number of printed dots, and the printing method is selected depending on the level of the printing density.

(Function) According to the present invention, the number of printing dots printed on the next line is counted, the printing density on the next line is calculated from the number of printing dots, and the above-mentioned printing method is selected depending on the level of the printing density. Therefore, when the print density of the next line is low, there is no need to unnecessarily reduce the printing speed or stop the print.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a control block diagram showing an embodiment of the print head temperature rise prevention method of the present invention.

In the figure, ■ is the main control unit that controls the printer, and 2 is 1
An image buffer that stores print data for a line as a bit image; 3 is a print density detection section that detects the density of the print data stored in the image buffer 2; 4 is print density information from the print density detection section 3; Bidirectional printing,
A print control section 5 is a print head which changes the printing method such as unidirectional printing and print body stopping.

In the control device configured as described above, print data is first sent from the main control section 1 to the image buffer 2.

At this time, the print density detection section 3 calculates the print density of one line using the following equation.

ρ-d/D Print density of 981 lines d: Number of printed dots in one line D: Total number of dots in one line Print data is sent from the image buffer 2 to the RAD 5 for printing, and is controlled by the print control unit 4. Printing is performed according to the signal. The printing control unit 4 is capable of performing bidirectional printing, unidirectional printing, pausing between lines, split printing, changing the printing speed, etc. in line units, and determines the printing method based on instructions from the printing density detection unit 3. change. When the printing method is changed, the number of printed dots per unit time is limited, and heating due to an increase in the temperature of the print head is prevented.

FIG. 2 shows details of the print density detection section.

In the printing density detection section 3, a printing dot loss adding section 6
calculates the number of printed dots in one line from the print data, while a total dot number addition unit 7 calculates the total number of dots in one line and sends it to the calculation unit 8. The calculation unit 8 calculates the print density of one line using the above formula, and the density comparison unit 9 compares it with a set value to determine the printing method.

FIG. 3 is a processing flow diagram of the density comparison section.

Here, three types of printing methods are used: "bidirectional printing", "unidirectional printing", and "unidirectional printing and pause between lines".

"Bidirectional printing" is a method in which the print head prints back and forth, and the load is large; "unidirectional printing" is a method in which the print head prints only in the outward path, and the load is small; "Pause" is a method in which the print head prints only on the outward path and also pauses printing between each line.
The load becomes even smaller.

The printing density increases in the order of Da, Db, and Dc. When the printing density is low (Da), "bidirectional printing" is used, and when the printing density is high (Db), "unidirectional printing" is used.
When the printing density is higher (Da), "unidirectional printing and pause between lines" is selected.

By finely setting the printing density and the fastest printing method at the printing density, it is possible to perform even higher throughput control.

FIG. 4 is a diagram showing the relationship between print density and print head internal temperature rise rate in each printing method.

The horizontal axis shows print density, and the vertical axis shows print head internal temperature rise rate, and the relationship between print density and print head internal temperature rise rate for each printing method is shown by each gland.

If the print head internal temperature increase rate exceeds 1, the print head internal temperature may rise and the print head may burn out.

Therefore, if you are printing using a certain printing method (1), at the point where that line intersects the line with a print head internal temperature increase rate of 1, you only need to change to a printing method with a smaller print head internal temperature increase rate. 0 For example, when bidirectional printing is performed, the print head internal temperature increase rate exceeds 1 at point P1 where the printing density changes from area Da to area Db, so at that point P, the printing is switched from bidirectional printing to unidirectional printing. That's fine.

By the way, in the above method for preventing a rise in print head temperature,
The printing method is determined solely by the print density. Therefore, even when the internal temperature of the print head is low, such as immediately after printing starts, if the printing density is high, the printing method may be changed and the throughput may be reduced.

FIG. 5 is a control block diagram showing a second embodiment of the print head temperature rise prevention method of the present invention.

In the figure, reference numeral 11 denotes a temperature detection section that detects the temperature of the print head, and it is selected whether or not to detect the print density based on the detected temperature. That is, by not changing the printing method depending on the print density until the temperature reaches the limit temperature at which the print head burns out, high-throughput printing can be performed.

FIG. 6 is a processing flow diagram of the density comparison section in the second embodiment.

First, it is determined whether the print head temperature has reached the limit temperature, and if it is below the limit temperature, "bidirectional printing" is performed.
The printing method is selected.

Then, when the temperature of the printing head reaches the limit temperature,
The print density detection section 3 determines the print density and determines the printing method.

That is, similar to the process flow diagram in Figure 3, "bidirectional printing" is used when the printing density is low (Da), "unidirectional printing" is used when the printing density is high (Db), and when the printing density is even higher (Db), "unidirectional printing" is used. If the value is high (Da), "unidirectional printing and pause between lines" is selected.

Note that the present invention is not limited to the above embodiments,
Various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

(Effects of the Invention) As described above in detail, according to the present invention, the printing method is determined by the next line printing density, and when the printing density is high, a printing method with a low load is selected; In some cases, printing can be performed without any downtime, so not only can overheating of the print head be prevented, but also high throughput can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a control block diagram showing an embodiment of the print head temperature rise prevention method of the present invention, FIG. 2 is a diagram showing details of the print density detection section, FIG. 3 is a processing flow diagram of the density comparison section, and FIG. The figure is a diagram showing the relationship between print density and print head internal temperature rise rate in each printing method, Fig. 5 is a control block diagram showing a second embodiment of the print head temperature rise prevention method of the present invention, and Fig. FIG. 3 is a processing flow diagram of the density comparison section in the embodiment. 1... Main control unit, 2... Image buffer, 3...
・Print density detection unit, 4...Print control unit, 5...Print head, 6...Print dot number addition unit, 7...Total dot number addition unit, 8...Calculation unit, 9. ...Density comparison section, 1
1...Temperature detection section. Patent Applicant: Oki Electric Industry Co., Ltd. Agent, Patent Attorney: Makoto Kawai (1 other person) Kurahu's Head Whispering Method for Preventing the Elevation of a Prayer Professional, Graphing, Writing Practice, A Detailed Description Figure 2 shows the flow diagram of the τ degree comparison section.

Claims (1)

[Claims] (a) A printing method consisting of a plurality of printing states and a pause state each having a different printing load can be selected by the print head, and (b) The number of printing dots to be printed in the next line is (c) calculating the printing density in the next line from the number of printed dots; and (d) selecting the printing method according to the level of the printing density.