JPH02245341A - Printing control system protecting printing head - Google Patents

Abstract

PURPOSE:To surely protect a printing head from a temperature rise due to a printing duty and to prevent a printing speed from dropping unexpectedly by detecting not only the temperature of the printing head but the changing speed of the temperature, selectively setting a protecting action start temperature according to the temperature and the changing speed, and protecting the printing head. CONSTITUTION:Normal printing is carried out, the temperature of a printing head 11 and its temperature rising speed DELTAT/DELTAt in an appropriate sampling cycle DELTAt, and T is obtained from a protecting action start temperature table 23. According to the T, the temperature of the printing head is monitored, and when the temperature exceeds T, the operation shifts to divided printing. Until the temperature of the printing head drops to a normal printing resuming temperature, the detection of a temperature dropping speed DELTAT/DELTAt continues. As long as DELTAT/DELTAt is appropriate, divided printing is going on, and when the normal printing resuming temperature is attained, the operation returns to normal printing. Conversely, when the temperature dropping speed DELTAT/DELTAt is too slow, a dormant time corresponding to the temperature of the printing head and its dropping speed are obtained from a dormant time table 24 to stop printing temporarily. Then, divided printing resumes to continue.

Description

[Detailed Description of the Invention] C Overview] This invention relates to a print control method that protects the print head by appropriately suppressing temperature rise during printer operation.

The purpose of this invention is to provide a print control method that reliably protects the print head against temperature increases due to arbitrary print duties and does not unnecessarily reduce print speed.

Equipped with a temperature detection element installed in the print head and a temperature change detection section that detects the temperature of the print head using the temperature detection element and detects the rate of temperature change, and corresponds to the detected temperature of the print head and the rate of temperature change. A predetermined appropriate limit temperature is set, and when the limit temperature is reached, a predetermined print head protection printing operation is started or restored.

[Industrial application field]

The present invention relates to a print control method for protecting the print head by appropriately suppressing temperature rise during operation of the print head in an impact type dot printer.

Printing in an impact dot printer [Prior art] The print head of an impact dot printer is equipped with a plurality of printing pins, each of which is independently driven by a magnetic coil.

Since the magnet coil is driven by a large current, it generates heat and raises its temperature. The amount of heat generated from the magnetic coil is
It is determined by the proportion of black dots included in the characters and figures to be printed. Therefore, the proportion of time during which current flows through the magnet coil within a unit time, that is, the duty, is generally larger when printing kanji or pictures than kana or alphanumeric characters.

If the heat generated by the magnet coil increases and its temperature rises above the limit, the magnet 7) coil will burn out or the magnetic properties of the core will deteriorate, reducing the impact force and causing uneven printing or missing dots. Problems such as this occurred.

For this reason, a temperature detection element is embedded in the print head, and when the temperature of the print head exceeds the limit, it switches to 5-divided printing and, for example, drives the print bin row by half to lower the duty and suppress the temperature rise. A method is being taken.

FIG. 6 shows an example of a conventional print head temperature detection mechanism, where l is the print head, 2 is a thermostat embedded in the print head 1, and 4 is a thermostat that responds to the thermostat 2. This is a print control unit that performs print head protection operations such as division printing.

Figure 7 shows the print head temperature rise control characteristics by the temperature detection mechanism using the thermostat shown in Figure 6.
The vertical axis is the actual coil temperature, the horizontal axis is time, and ■, ■, and ■ indicate the control characteristics when the printing duty is ■〉■〉■, respectively.The upper dotted line of the two dotted lines in Figure 6 is the protective operation start temperature at which the thermostat closes, and when the temperature rises, the protective operation such as division printing is started from this temperature.

The lower dotted line is 2 normal printing recovery temperature, and when the temperature drops, the protective operation up to that point is canceled and 9 the normal printing operation returns.

Now, looking at the control characteristics (2) and (2) when the printing duty is large in FIG. 7, the coil temperature continues to rise for a certain period of time even after the protection operating temperature is exceeded.

This occurs because there is a slight distance between the magnet coil and the thermostat, and thermal impedance exists between them, so that heat from the magnet coil is transferred to the thermostat with a delay.

[Problem to be solved by the invention]

With the conventional method of detecting temperature by embedding a thermostat in the print head, it is not possible to detect the actual temperature of the magnet coil, so if the printing duty is large, the temperature of the magnet coil may overrun even if a protective operation is performed. This resulted in problems such as burnout of the coil and deterioration of printing quality. However, if the protective operation start temperature is set low for this purpose, the protective operation is started early even in the case of printing with a small duty, resulting in a disadvantage that the printing speed decreases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a print control method that reliably protects a print head against temperature increases due to any print duty and does not unnecessarily reduce print speed.

[Means to solve the problem]

The present invention makes it possible to set the optimum protective operation start temperature according to the size of the print duty. Therefore, the temperature change rate of the temperature is detected as well as the print head temperature, and the The protective operation start temperature is selected and set, and the protective operation is performed.

FIG. 1 is a diagram showing the basic configuration of the present invention.

In the figure 9 11 is an impact type print head.

12 is a thermistor as a temperature detection element.

13 is a printer control device.

14 is a temperature change detection section, which detects the temperature TI' based on the temperature detection signal from the thermistor 12.
.

dynamically changed.

Then, select the optimal protection operation start temperature T1, and select this T! is used to monitor T1' to determine whether to start a protective operation when the temperature rises. Furthermore, when the temperature drops, it is also determined whether to restore to 1 normal printing or stop printing.

16 is a print control unit, which includes a protection operation start recovery determination unit 1;
Printing control such as normal printing, one-division printing, and printing is performed in accordance with the determination result of protection operation start, restoration, and suspension in step 5.

[Effect]

In the print control method of the present invention, the protection operation start temperature is set based on the print head temperature and temperature change rate.
If printing continues based on the current temperature of the print head and the rate of temperature rise, when it is predicted that a dangerous temperature will be reached within a predetermined time, the optimum protective operation start temperature is set to avoid this. Embodiment FIG. 2 shows the configuration of one embodiment of the present invention.

In the figure, 11 is a print head, 12 is a thermistor, 1
7 is an A/D conversion unit that converts the temperature detection signal from the thermistor 12 into a digital signal, 18 is an entrance boat, 19 is a bus, 20 is an MPU, 21 is a ROM, and 22 is a print head protection operation control according to the present invention. A control program that performs
3 is a protection operation start temperature table that corresponds to the temperature of the print head and the rate of temperature increase; 24 is a pause time table that indicates the value of the pause time to be set when the temperature decrease rate is too small; and 25 is a work area for print control. This is the RAM used.

FIG. 3 shows the structure of the protection operation start temperature table 23 in FIG. 2. Here, the current print head temperature is T. l,
7, l,...I TtI', and the temperature increase rate at that time is ΔT0'/Δt, ΔT I'/Δt
.

..., by specifying from among ΔT n' /Δt.

The corresponding protection operation start temperature is 'r1. 'r! ,...,
Obtained from TA.

FIG. 4 shows the structure of the pause time table 24 in FIG. 2, where the current print head temperature is T0''T1#, . . .
・, TI, ', and the temperature decrease rate at that temperature is ΔT0'/Δt, ΔT1'/Δt.

..., ΔT r: by specifying from among /Δt.

The corresponding pause time is obtained from i0+tl+..., tl.

FIG. 5 shows a control flow of the control program 22 in FIG. 2, and will be explained below according to the procedure.

When printing starts, 1 normal printing (100% printing) is executed. The print head temperature and temperature increase rate ΔT/Δt are calculated using a suitable sampling period Δt.

Find T from the protection operation start temperature table.

This T is then used to monitor the print head temperature.

When T is exceeded, division printing (for example, 50% printing) is started. After that, the temperature drop rate ΔT/Δt is detected until the print head temperature falls to the normal printing recovery temperature, and then
It is checked whether Δt indicates an appropriate rate of decline, and division printing is continued as long as it is appropriate, and when the 1 normal printing recovery temperature is reached, normal printing is resumed.

On the other hand, if the temperature decrease rate ΔT/Δt is not appropriate, that is, if the rate of decrease is too slow, find a pause time according to the print head temperature and rate of decrease from the pause time table, pause printing, and then print again in divided prints. Continue.

〔Effect of the invention〕

According to the present invention, the protection operation start temperature suitable for each condition is dynamically set regardless of the size of the print data, so that unnecessary divided printing is avoided by following various print contents. It is possible to suppress excessive temperature rise of the print head without causing any problems, and to perform efficient print processing with high print quality.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the basic configuration of the present invention, FIG. 2 is a diagram showing the configuration of one embodiment of the present invention, FIG. 3 is a diagram showing the configuration of a protection operation start temperature table, and FIG. 4 is a diagram showing the configuration of a rest time table. FIG. 5 is a control flow diagram of one embodiment of the present invention, FIG. 6 is a configuration diagram of a conventional print head temperature detection mechanism, and FIG. 7 is an explanatory diagram of conventional print head temperature increase control characteristics. 1 in Figure 1: Print head 12: Thermistor 13: Printer control device 14: Temperature change detection unit 15: Protective operation start recovery determination unit 16: Print control unit Patent applicant Pfn Co., Ltd. Attorney Patent attorney Fumihiro Hase (Other 2 people) Plan 3 7, Le Se J Mesu 1 7゛)

Claims (1)

[Scope of Claims] A temperature detection element provided in the print head, and a temperature change detection section that detects the temperature of the print head using the temperature detection element and detects the speed of temperature change, and detects the detected temperature of the print head. and a predetermined appropriate limit temperature corresponding to the rate of temperature change, and when the limit temperature is reached, a predetermined print head protection printing operation is started or restored, etc. A print control method that protects the print head.