JP4353595B2 - Thermal printer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermal printer that prints dots on a medium for each line by a thermal head.
[0002]
[Prior art]
A ticket issuing terminal device that prints on a predetermined medium and issues it as a ticket is used in various fields.
A thermal printer used in such a ticket issuing terminal device or the like is provided with a thermal head that arranges heating elements for one line in the line direction of printing and prints printing data as dots for each line. is there.
[0003]
FIG. 7 is a time chart for printing in this type of conventional printer.
In the figure, TMG is a timing signal that is output for each line of printing in synchronization with the rotation of the motor that transports the medium to be printed. When this timing signal TMG is output, the thermal head prints dots for one line. When the printing for one line is completed, the thermal head waits until the next timing signal TMG is output.
[0004]
MEM is a data bus signal of the print data storage memory, and the data bus signal is used to access the print data storage memory and take out print data for one line.
DATA is a data signal transferred to the thermal head.
ENB is an enable signal for the thermal head. This enable signal ENB is low active. When the low signal is low, the thermal head is energized, and the medium is colored.
[0005]
Here, the enable signal ENB is divided into three because one dot is divided into three times for printing, and the energy of one dot is adjusted according to how many times the current is energized. Thus, printing of one line is performed by activating the enable signal ENB after the transfer of print data to the thermal head for one line to be printed is completed.
[0006]
In this way, dots are printed on a predetermined medium. Conventionally, as shown in this figure, the print data storage memory is accessed by a data bus signal just before the next timing signal TMG is output. It has become.
Therefore, the MIN value of the timing signal interval, which is a reference for determining whether the printing timing signal is normal or abnormal, is the end of access to the print data storage memory for the next printing after the current timing signal TMG is output. The timing signal TMG output at an interval smaller than the MIN value is determined as an error, and printing is stopped.
[0007]
[Problems to be solved by the invention]
However, in the conventional technique described above, the MIN value of the timing signal interval is set as a relatively large value with respect to the specified timing signal interval, so even when the timing signal interval is slightly shortened due to noise or the like, for example. There was a problem that it would be treated as an error immediately.
[0008]
In order to deal with such problems, a method has been proposed in which the normal signal and the abnormal signal are divided according to the interval of the printing timing signal, and in the case of the abnormal signal, the signal is ignored and printing is continued. Therefore, if the timing signal of printing is judged to be an abnormal signal, it will be ignored, so if the timing signal interval becomes shorter due to the speed fluctuation of the motor that transports the medium instead of noise, the timing signal will be ignored. There is a problem in that the print dots in the corresponding part are lost.
[0009]
Accordingly, an object of the present invention is to realize a thermal printer that can prevent printing dots from dropping out and continue printing even when the timing signal interval is shortened due to fluctuations in the speed of the motor that transports the medium. .
[0010]
[Means for Solving the Problems]
Therefore, according to the present invention, print data for one line is taken out from the print data storage memory and sent to the thermal head, and one line is printed on the medium by the thermal head based on the print timing signal output for each print data line. In the thermal printer that performs printing, when the print data storage memory for the next printing is accessed immediately after the printing timing signal is output and the next timing signal is output during printing for one line, If the reading of the printing data from the printing data storage memory has been completed , the printing of the line is interrupted and the process proceeds to the printing of the next line.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a thermal printer according to the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing the first embodiment.
In the figure, reference numeral 1 denotes a control unit, and the control unit 1 has an abnormal timing detection unit 2 for detecting an abnormality from an interval of timing signals.
[0012]
A print data storage memory 3 stores print data in an image format, and print data is stored by a CPU (not shown in the figure) prior to printing.
Reference numeral 4 denotes a parallel / serial converter that performs parallel / serial conversion on the print data extracted from the print data storage memory 3.
Reference numeral 5 denotes a line data memory for recording whether or not there is black data (colored dots) in the past 1 to n lines for each dot.
[0013]
Reference numeral 6 denotes a history memory. The history memory stores a parameter for heat history control indicating how much energy is applied based on data from the line data memory 5.
The operation of this configuration will be described.
First, at the time of printing, the print data is taken out from the print data storage memory 3 by the control unit 1, parallel / serial converted by the parallel / serial converter 4, and then transferred to the line data memory 5. Update the contents of the line.
[0014]
Thereafter, the print data for one line is sent from the line data memory 5 to the history memory 6 and converted so as to have more appropriate energy, and the converted print data is transferred to the thermal head for printing. Do.
FIG. 2 is a time chart for normal printing in the first embodiment described above.
[0015]
In the figure, TMG is a timing signal, MEM is a data bus signal of the print data storage memory 3, DATA is a data signal to be transferred to the thermal head, ENB is an enable signal for the thermal head, and these signals are the conventional ones shown in FIG. It corresponds to.
Here, the timing signal TMG is output by a circuit (not shown) for each line of print data in synchronization with the speed of the motor for transporting the medium, and is given to the control unit 1.
[0016]
Further, the print data storage memory 3 is accessed by the address output from the control unit 1 to the print data storage memory 3 based on the timing signal TMG, and the print data (data bus signal MEM) is read out. In this embodiment, the access to the print data storage memory 3 for acquiring the data bus signal MEM is set immediately after the print synchronization timing signal issued for each print data line.
[0017]
Further, since the access to the print data storage memory 3 is set in this way, in this embodiment, the MIN value of the timing signal interval serving as a reference for determining whether the print timing signal TMG is normal or abnormal is specified. The timing signal interval can be reduced.
When a timing signal is output at an interval equal to or smaller than the MIN value, the abnormal timing detection unit 2 detects the timing signal as an abnormal signal, and printing is stopped by the control unit 1, but in this embodiment, the MIN value is set. Printing is continued even if the interval exceeds the specified interval.
[0018]
FIG. 3 is a time chart showing the operation when the interval of the timing signal TMG is shorter than a predetermined interval, that is, when an abnormality occurs.
As shown in this figure, when the interval between the preceding timing signal TMG and the next timing signal TMG becomes shorter than the prescribed interval due to speed fluctuation or noise of the motor carrying the medium, the control unit 1 If the access to the print data storage memory 3 is completed when the timing signal TMG is output, that is, if the interval exceeds the MIN value, the transfer of the print data to the thermal head currently being executed is aborted and the line The printing of the next line is started, and the transfer of the printing data of the next line is newly started to cause the thermal head to print the next line.
[0019]
In this case, the enable signal ENB may be stopped once when the transfer of the print data is stopped, or the application of the enable signal ENB may be continued until the data transfer of the next line is completed. The enable signal ENB is continuously applied so as not to reduce the applied energy as much as possible.
As described above, according to the first embodiment, the print data storage memory is accessed immediately after the output of the timing signal output for each line of print data. If the access to the print data storage memory is completed before the timing signal is output, the printing operation is continued without causing an error even if the timing signal interval is shorter than specified. Therefore, it is possible to prevent the printing dots from dropping out.
[0020]
FIG. 4 is a block diagram showing the second embodiment.
In this embodiment, an abnormality timing count unit 7, a limit number setting unit 8, and a comparator 9 are added to the configuration of the first embodiment.
Here, in the first embodiment, when the timing signal TMG is output at an interval that is larger than the MIN value of the timing signal interval and shorter than specified in the first embodiment, the abnormality timing count unit 7 is notified by the notification from the abnormality timing detection unit 2. It counts up each time, and the CPU can read it.
[0021]
The limit number setting unit 8 stores the limit number when the timing signal TMG is output at an interval larger than the MIN value of the timing signal interval and shorter than the specified value. This limit number is arbitrarily set in advance and written by the CPU. ing.
The comparator 9 compares the count value of the abnormality timing count unit 7 with the limit number stored in the limit number setting unit 8 and notifies the control unit 1 of the comparison result.
[0022]
Next, the operation will be described.
First, as for printing, as in the first embodiment, if access to the print data storage memory is completed between the preceding timing signal and the next timing signal, even if the timing signal interval is shorter than specified. The printing operation is continued without an error.
[0023]
Therefore, when the printing operation is started, when the timing signal TMG is output at an interval larger than the MIN value of the timing signal interval and shorter than the specified value, the abnormality timing count unit 7 increments “+1” by the notification from the abnormality timing detection unit 2. Count up.
The comparator 9 compares the count value of the abnormality timing count unit 7 with the limit number stored in the limit number setting unit 8, and notifies the control unit 1 when the count value becomes larger than the limit number. Thus, the control unit 1 determines that there is an error, stops printing, and notifies the CPU of error information.
[0024]
In this embodiment, even if there is a notification from the comparator 9 to the control unit 1, the control unit 1 does not make an error, and the CPU reads the count value of the abnormal timing count unit 7 at the end of printing, Abnormality is judged and if it is abnormal, the subsequent printing can be stopped.
According to the second embodiment described above, when a timing signal is output at an interval shorter than a specified interval, an abnormal timing count unit that counts the number of times is output, and a timing signal is output at an interval shorter than the specified interval. If the count value of the abnormal timing count section exceeds the limit count, printing is stopped as an error, so the quality of the print density as a whole is provided. Can be maintained.
[0025]
FIG. 5 is a block diagram showing a third embodiment.
In this embodiment, a limit position setting unit 10 and a timing position detection unit 11 are added to the configuration of the first embodiment.
Here, the limit position setting unit 10 can write a limit position preset by the CPU (the interval between the preceding timing signal and the next timing defined by the limit position (limit interval)).
[0026]
Further, the timing position detection unit 11 detects the position of the timing signal notified from the abnormality timing detection unit 2, and the detection position is in front of the limit position stored in the limit position setting unit 10 (within the limit interval). In this case, the control unit 1 is notified of the information.
Next, the operation will be described.
[0027]
FIG. 6 is a time chart showing the operation of the third embodiment.
In this time chart, the printing operation state when the printing data for one line is divided into three times to print dots is divided into blocks and subdivided, and each is assigned a number.
Here, (1) is the state during the transfer of the second print data, (2) is the state where the transfer of the second print data is completed, and the first print data is being printed, and (3) is the third time A state in which the print data is being transferred. (4) is a state in which the third data transfer is completed and the second print data is being printed.
[0028]
In this embodiment, the limit position at which the next timing signal TMG is output after the timing signal TMG is output is set as the position during transfer of print data for the third time, and the position data is limited. It is stored in the position setting unit 10.
As for printing, as in the first embodiment, if access to the print data storage memory is completed between the preceding timing signal and the next timing signal, even if the timing signal interval is shorter than specified, It is assumed that the printing operation is continued without an error.
[0029]
Therefore, in the printing, when the timing position detection unit 11 detects the position of the timing signal TMG notified from the abnormality timing detection unit 2 and the detection position is before the limit position stored in the limit position setting unit 10, The information is notified to the control unit 1.
As a result, the control unit 1 determines that there is an error, stops printing, and notifies the CPU of error information.
[0030]
In this embodiment, the printing operation state is divided into blocks and the limit position is set and stored in the limit position setting unit 10; however, the preceding timing signal is set by time instead of the block. A limit time from TMG to the next timing timing signal TMG is set, and this is stored in the limit time setting unit. If the time between timing signals is the limit time, printing is stopped as an error. Also good.
[0031]
According to the third embodiment described above, a limit position setting unit that stores a limit position (limit interval) when a timing signal is output at an interval shorter than a predetermined interval is provided, and the position of the timing signal is Since the printing is stopped as an error before the limit position (within the limit interval), it is possible to prevent the generation of a line with extremely low printing density. For example, even one line such as barcode printing can be prevented. With respect to a medium that causes a problem when there is a thin line for printing, a medium with poor printing can be eliminated.
[0032]
The present invention is not limited to the above-described embodiment. For example, a print data line in which the timing signal interval is equal to or less than a preset limit value by combining the second embodiment and the third embodiment. And the printing may be stopped as an error when the count value exceeds a preset limit number.
[0033]
【The invention's effect】
As described above, the present invention takes out print data for each line from the print data storage memory, sends the print data to the thermal head, and prints the medium by the thermal head based on the print timing signal output for each print data line. In a thermal printer that prints one line at a time, the print data storage memory for the next print is accessed immediately after the print timing signal is output, and the next timing signal is output during the print of one line. If the reading of the print data from the print data storage memory has been completed , the printing of the line is interrupted and the next line is printed. However, since the printing operation is continued without causing an error, the missing print dots are prevented. Door can be.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first embodiment.
FIG. 2 is a time chart showing the normal operation of the first embodiment.
FIG. 3 is a time chart showing an operation when an abnormality occurs in the first embodiment.
FIG. 4 is a block diagram showing a second embodiment.
FIG. 5 is a block diagram showing a third embodiment.
FIG. 6 is a time chart showing the operation of the third embodiment.
FIG. 7 is a time chart showing the prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Control part 2 Abnormal timing detection part 3 Print data storage memory 4 Parallel / serial converter 5 Line data memory 6 History memory 7 Abnormal timing count part 8 Limit number setting part 9 Comparator 10 Limit position setting part 11 Timing position detection part

Claims (4)

A thermal printer that extracts print data for each line from the print data storage memory, sends the print data to the thermal head, and prints one line on the medium by the thermal head based on a print timing signal output for each print data line. In
Immediately after the printing timing signal is output, the print data storage memory for the next printing is accessed.
If the next timing signal is output at an interval shorter than the specified interval during printing for one line, if the reading of the print data from the print data storage memory has been completed , the printing of the line is interrupted halfway, A thermal printer characterized by shifting to printing of the next line. In claim 1,
Set the limit number of timing signals output at intervals shorter than the specified interval,
A thermal printer characterized by stopping printing as an error when the number of timing signals output at intervals shorter than a specified interval exceeds a limit number. In claim 1,
Set the timing signal limit interval,
A thermal printer characterized by stopping printing as an error when the timing signal interval is shorter than the limit interval. In claim 1,
Set the limit number of timing signals output at intervals shorter than the specified interval and the timing signal limit interval,
A thermal printer that counts print data lines whose timing signal interval is less than or equal to a limit value, and stops printing as an error if the count value exceeds the limit number.

Images