JP2004338094A - Thermal head recorder and recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a thermal head recorder in which the recording sheet of a page under printing is prevented from being wasted upon occurrence of overheat alarm of a thermal head. <P>SOLUTION: The thermal head recorder comprises a section 2 for storing the number of black dots on each page of a document to be printed, a section 5 for detecting current temperature of a thermal head, a section 3 for determining a print start threshold temperature indicative of printability of a page of the document depending on the stored number of black dots, and a section 4 for deciding whether printing can be started or not by comparing the detected current temperature with the threshold temperature. The thermal head recorder is arranged to start printing of one stored page of the document by means of the thermal head 6 when a decision is made that printing can be started. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a thermal head recording apparatus and method for predicting the temperature of a thermal head during printing to prevent overheating of the thermal head.
[0002]
[Prior art]
In a facsimile apparatus and the like, a thermal head recording method for recording on thermal paper or the like using a thermal head is often used.
In such a recording apparatus that performs printing using a thermal head, the larger the number of black dots in an image to be printed, the more heat (electric power) is required for printing, and thus the amount of heat generated by the thermal head itself increases. .
[0003]
In this case, if the temperature of the thermal head exceeds a certain limit, the thermal head may be destroyed due to overheating.Therefore, a temperature detecting element such as a thermistor is arranged on the thermal head itself or in the vicinity thereof, and the thermal head is constantly operated during printing. Temperature monitoring is being performed.
When the thermal head reaches a certain temperature or higher, a general method is to generate an overheat alarm, terminate printing halfway, and then pause printing to cool the thermal head. It is.
In this case, as a timing for restarting printing according to cooling of the thermal head, a method after a fixed pause time and a method after the temperature of the thermal head has decreased to a predetermined temperature are generally used. Have been.
[0004]
When printing is terminated in the middle, usually, after the thermal head is cooled, reprinting of pages subsequent to the page where the printing operation is stopped is performed manually.
It is to be noted that a method has been proposed in which, when the printing operation is stopped, after the thermal head is cooled, reprinting is automatically performed from the image information after the page where the printing operation is stopped, except for the page on which the printing operation has been stopped (for example, see Patent Reference 1).
[0005]
[Patent Document 1]
JP 2000-29547 A
[Problems to be solved by the invention]
In the method of stopping the printing operation and waiting for the thermal head to cool when the temperature rise of the thermal head is detected, the recording paper that has been printed halfway through the page when the thermal head overheat alarm occurs The recording paper is discharged without being printed, so that the recording paper is wasted when the printing is stopped.
[0007]
In the method of keeping the thermal head cooling down time constant, the thermal head may not be sufficiently cooled when printing is resumed.In this case, even if reprinting is performed, the overheating alarm Is generated, so that the recording paper is further wasted.
Conversely, if the cooling of the thermal head is performed more than necessary, time is wasted for cooling and the user of the facsimile apparatus is left unnecessarily waiting.
[0008]
The present invention has been made in view of the above circumstances, and in a thermal head recording apparatus such as a facsimile apparatus, a recording sheet of a page being printed is wasted due to a print pause caused by the occurrence of a thermal head overheat alarm. It is an object of the present invention to provide a thermal head recording apparatus and method capable of preventing printing and appropriately setting a print pause time.
[0009]
[Means for Solving the Problems]
In order to solve the above problem, the invention according to claim 1 relates to a thermal head recording apparatus for printing a document by a thermal head, and a black dot number storage means for storing the number of black dots in a document to be printed for each page. A temperature detecting means for detecting a current temperature of the thermal head, and a threshold value for determining a printing start temperature threshold value indicating that a document of one page can be printed according to the stored number of black dots. Value determining means, comparing the detected current temperature and the threshold temperature, and comprising a print start determining means for determining whether or not to start printing, the determination result, when printing start is possible, the The printing of the stored one-page document by the thermal head is started.
[0010]
According to a second aspect of the present invention, there is provided the thermal head recording apparatus according to the first aspect, wherein the number of black dots stored in the number-of-black-dots storage section is equal to the number of black dots in the document to be printed by the black dot counting means. Is based on the count result.
[0011]
According to a third aspect of the present invention, there is provided the thermal head recording apparatus according to the first or second aspect, wherein the printing start temperature threshold value is stored in advance in a printing start temperature threshold value storage means. -It is characterized in that it corresponds to the stored number of black dots in the printing start temperature threshold value conversion table.
[0012]
According to a fourth aspect of the present invention, there is provided the thermal head recording apparatus according to any one of the first to third aspects, wherein the thermal head recording apparatus is a facsimile apparatus.
[0013]
The invention according to claim 5 relates to a thermal head recording method for printing a document by a thermal head, wherein the number of black dots in a document to be printed is stored for each page and the current temperature of the thermal head is detected. Then, a printing start temperature threshold value indicating that printing of a document of one page is possible is determined according to the stored number of black dots, and the detected current temperature and the threshold temperature are determined. Are compared to determine whether or not printing can be started. When the determination result indicates that printing can be started, printing of the stored one-page document by the thermal head is started.
[0014]
According to a sixth aspect of the present invention, there is provided the thermal head recording method according to the fifth aspect, wherein the stored number of black dots is based on a count result of the number of black dots in a document to be printed. Features.
[0015]
According to a seventh aspect of the present invention, there is provided the thermal head recording method according to the fifth or sixth aspect, wherein the printing start temperature threshold value is stored in advance, and a black dot-printing start temperature threshold value conversion table is stored. , Corresponding to the stored number of black dots.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. The description will be made specifically using an embodiment.
FIG. 1 is a block diagram showing a configuration of a facsimile apparatus according to one embodiment of the present invention, FIG. 2 is a view showing a black dot-print start temperature threshold conversion table in this embodiment, and FIG. FIG. 4 is a flowchart showing a receiving operation and a black dot number counting operation in the example, and FIG. 4 is a flowchart showing a printing operation in the present embodiment.
[0017]
As shown in FIG. 1, the facsimile apparatus of this example includes a black dot counter 1, a black dot number storage unit 2, a threshold value determination unit 3, a print start determination unit 4, a temperature detection unit 5, a thermal detection unit 5, It is roughly composed of a head 6, a print control unit 7, an image processing unit 8, an image memory 9, and a print start temperature threshold storage unit 10.
[0018]
The black dot counter 1 receives print data from the outside and counts the number of black dots for each page. The black dot number storage unit 2 stores the number n of black dots for each page counted by the black dot counter 1. The threshold value determination unit 3 obtains the number n of black dots of the page to be printed from the number-of-black-dots storage unit 2, and uses the black dot-printing start temperature threshold value conversion table to convert the printing start temperature threshold. Determine the value Tth.
[0019]
The print start determination unit 4 obtains the current thermal head temperature T0 from the temperature detection unit 5, compares it with the print start temperature threshold value Tth notified from the threshold value determination unit 3, and determines whether printing can be started. Then, the result is notified to the print control unit 7. The temperature detector 5 has a temperature sensor such as a thermistor, and detects the current temperature T0 of the thermal head. The thermal head 6 performs printing on recording paper such as thermal paper (not shown) under the control of the print control unit 7.
[0020]
When the print control unit 7 receives a print start notification from the print start determination unit 4, the print control unit 7 obtains print data on which image processing has been performed from the image processing unit 8, and drives the thermal head 6 to perform printing. Is performed. The image processing unit 8 performs image processing on print data obtained from the image memory 9. The image memory 9 temporarily stores the image data output from the black dot counter 1. The print start temperature threshold storage unit 10 stores a black dot-print start temperature threshold conversion table for determining a temperature threshold at which printing can be started from the number of black dots for each page.
[0021]
In the black dot / print start temperature threshold value conversion table, the correspondence between the number n of black dots and the print start temperature threshold value Tth as shown in FIG. 2 is set in advance.
This table indicates the range of the number of black dots at which an overheating alarm does not occur if the thermal head temperature at the start of printing is equal to or lower than the printing start temperature threshold Tth when printing a one-page document. For example, if the number n of black dots is n2 <n <n3, as shown in FIG. 2, the print start temperature threshold Tth is T2.
In this case, as the number n of black dots increases, the temperature rise of the thermal head during printing also increases. Therefore, as the printing start temperature threshold Tth, a lower value is set as the number n of black dots increases.
[0022]
Next, a receiving operation and a black dot number counting operation in this example will be described with reference to a flowchart shown in FIG.
At the start of the black dot number counting operation, the black dot counter 1 receives image data to be printed, and counts the number of black dots included in the print data (step S10). The image data to be printed after the number of black dots has been counted is stored in the image memory 9 as needed (step S11).
[0023]
Next, the black dot counter 1 determines whether or not the received print data is the data at the end of the page (step S12). If not, the document data in the middle of the page is received. Since it is in the state, the process returns to step S10, and the number of black dots of the next print data is continuously counted.
[0024]
If the print data at the end of the page is found in step S12, the number n of black dots of the received page is stored in the number-of-black-dots storage unit 2 (step S13), and it is determined whether there is a next page. If there is a next page (step S14), the flow returns to step S10 to continue counting the number of black dots in the print data of the next page.
[0025]
If there is no next page in step S14, it means that all the documents have been received, and the process of counting the number of black dots is terminated.
By performing the processing described above, the number n of black dots for each page of the received document is collected.
[0026]
Hereinafter, the printing operation in this example will be described with reference to the flowchart shown in FIG.
At the start of the printing process, the threshold value determination unit 3 obtains the number n of black dots of the page to be printed from the black dot number storage unit 2 and checks it (step S20).
Next, the threshold value determination unit 3 uses a black dot-print start temperature threshold conversion table as shown in FIG. 2 and stored in the print start temperature threshold storage unit 10. The print start temperature threshold value Tth corresponding to the number n of black dots obtained in step S20 is determined (step S21), and this is notified to the print start determination unit 4.
[0027]
On the other hand, the temperature detector 5 measures the current thermal head temperature T0 (step S22). The print start determination unit 4 compares the print start temperature threshold value Tth notified in step S21 with the current thermal head temperature T0 measured by the temperature detection unit 5 (step S23). If .ltoreq.T0, it is predicted that a thermal head overheat alarm will occur during printing, so steps S22 to S23 are looped to wait for the thermal head to cool.
[0028]
If Tth> T0 as a result of the comparison in the print start determination section 4, it is predicted that the thermal head overheat alarm will not occur during printing, so the print start section is notified of the print start OK to the print control section 7. The print control unit 7 starts a printing process (step S24).
The print control unit 7 transfers the image data stored in the image memory 9 to the print control unit 7 via the image processing unit 8. Thus, the print control unit 7 drives the thermal head 6 according to the transferred image data to perform printing.
[0029]
In this way, after the printing process for one page is completed, if there is a next page, the process returns to step S20 to repeat the same process again. If there is no next page, the printing process is terminated (step S20). S25).
[0030]
Thus, in the thermal head recording method of this example, the number of black dots is counted in advance for each page to be printed, and based on the counted number of black dots and the current thermal head temperature, Judgment of the start of printing is made, and during the printing operation of the page, it is predicted that the thermal head overheat alarm will not occur, and printing will be started. Since printing is paused halfway, it is possible to prevent the recording paper from being ejected when printing has been performed halfway and without subsequent printing, thus avoiding wasteful consumption of recording paper. It becomes possible to do.
Further, since the cooling time of the thermal head is appropriately adjusted according to the number of black dots of the document to be printed next, it is possible to prevent a wasteful waiting time for waiting for cooling of the thermal head. .
[0031]
As described above, the embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and even if there is a design change or the like within a range not departing from the gist of the present invention. Included in the invention. For example, the thermal head recording apparatus of this example is not limited to a facsimile apparatus, but can be applied to any apparatus employing a thermal head recording method. The facsimile machine may be a thermal paper facsimile machine or a plain paper facsimile machine that prints on plain paper through an ink film. Instead of counting the number of black dots to be printed by the counter, the number of black dots specified for each page of the document from outside may be used.
[0032]
【The invention's effect】
As described above, in the thermal head recording apparatus and method of the present invention, the number of black dots is counted in advance for each page to be printed, and the number of black dots for one page and the current thermal head temperature are determined. Judgment of whether to start printing is made based on this, and printing is started by predicting that the thermal head overheating alarm will not occur during printing of each page. Since the paper is discharged in a state where it is printed halfway through the page, it can be prevented from being wasted.
In addition, the printing pause time for cooling the thermal head can be adjusted to an appropriate time according to the number of black dots of the document to be printed next. In addition, it is not necessary to uselessly wait for cooling the thermal head.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a facsimile apparatus according to one embodiment of the present invention.
FIG. 2 is a diagram showing a black dot-printing start temperature threshold value conversion table in the embodiment.
FIG. 3 is a flowchart showing a receiving operation and a black dot number counting operation in the embodiment.
FIG. 4 is a flowchart showing a printing operation in the embodiment.
[Explanation of symbols]
1 Black dot counter (black dot counting means)
2 Black dot number storage unit (black dot number storage means)
3 Threshold value determination unit (threshold value determination means)
4 Print start judgment unit (Print start judgment means)
5 Temperature detector (temperature detector)
6 Thermal head 7 Print control unit 8 Image processing unit 9 Image memory 10 Print start temperature threshold storage unit (print start temperature threshold storage unit)

Claims (7)

In a thermal head recording device that prints a document with a thermal head,
Black dot number storage means for storing the number of black dots in a document to be printed for each page;
Temperature detection means for detecting the current temperature of the thermal head,
Threshold value determining means for determining a printing start temperature threshold value indicating that printing of one page of a document is possible according to the stored number of black dots;
Comparing the detected current temperature and the threshold temperature, a print start determining means for determining whether to start printing,
The thermal head recording apparatus is configured to start printing of the stored one-page document by the thermal head when the determination result indicates that printing can be started. 2. The thermal head recording apparatus according to claim 1, wherein the number of black dots stored in the number-of-black-dots storage section is based on the result of counting the number of black dots in a document to be printed by the black dot counting means. . The print start temperature threshold value corresponds to the stored number of black dots in a black dot-print start temperature threshold value conversion table stored in advance in a print start temperature threshold value storage unit. The thermal head recording apparatus according to claim 1, wherein the thermal head recording apparatus is provided. 4. The thermal head recording device according to claim 1, wherein the thermal head recording device is a facsimile device. A thermal head recording method for printing a document by a thermal head, wherein the number of black dots in a document to be printed is stored for each page, the current temperature of the thermal head is detected, and the stored black dot is detected. A printing start temperature threshold value indicating that printing of one page of document can be performed is determined according to the number of dots, and the detected current temperature is compared with the threshold temperature to determine whether printing can be started. And when the determination result indicates that printing can be started, printing of the stored one-page document by the thermal head is started. 6. The thermal head recording method according to claim 5, wherein the stored number of black dots is based on the result of counting the number of black dots in a document to be printed. 6. The printing start temperature threshold value corresponds to the stored number of black dots in a black dot-printing start temperature threshold value conversion table stored in advance. Or the thermal head recording method according to 6.

Images