JPH05238044A - Thermal printer - Google Patents

Abstract

PURPOSE:To maintain printing quality uniformly by setting applied voltage in consideration of both the temperature of a thermal head and the temperature of a form in continuous issuance at high speed. CONSTITUTION:An applied-voltage data V1 is read from a temperature table based on a temperature data T1 from a temperature sensor and various conditions, a correction rank is then read from a correction rank table based on conditions such as printing speed, an ambient temperature, a printing rate, etc., and the numeric value of a correction value Ca is read from a correction value table based on the correction rank every time the number of previous issuance (i) reaches the number of correction setting na (100Xa, a=1, 2, 3,...) and it is set at the time of continuous issuance, in which the number of issuance is designated. Each applied-voltage data V1 read is corrected by the numeric value of the correction value Ca set, and a voltage is applied to a thermal head according to thus corrected applying voltage data V and printing issuance is conducted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal printer that controls the voltage of a thermal head to print on paper.

[0002]

2. Description of the Related Art In a conventional thermal printer, label paper is printed by a thermal head whose voltage is controlled. The voltage control of the thermal head is performed by, for example, direct printing using a thermal paper or transfer printing using an ink ribbon, rank of the resistance value (head resistance value) of the heating resistor forming the thermal head, printing speed, thermal The voltage value applied to the thermal head (each heating resistor) is set in consideration of various conditions such as the temperature of the head. That is, it is equipped with a temperature table in which the appropriate voltage to be applied to the thermal head is set in advance by direct printing or transfer printing, the resistance value rank of the heating resistor, the printing speed, the temperature of the thermal head, etc. Was detected, the appropriate voltage was read from the temperature table according to the temperature data, and the read voltage was applied to the thermal head.

[0003]

In the thermal printer as described above, when a plurality of labels are continuously printed at high speed, the thermal head itself is heated by the heat generated by the heating resistor during printing, and the ambient temperature is raised. In addition, a large temperature difference occurs with respect to the temperature of the paper.

Generally, in order to print on a sheet with a desired print density by the thermal head, it is necessary that the heating resistors corresponding to the dots printed by the thermal head reach a predetermined proper printing temperature. Therefore, in the temperature table, the applied voltage for heating required to reach the printing temperature from the temperature of the thermal head detected before printing is set.

However, since the temperature of the paper which the thermal head contacts is not taken into consideration in this temperature table, the temperature difference between the thermal head and the paper becomes large, and the applied voltage read from the temperature table causes printing. There was a problem that it became thin. That is, there is a problem that the printing quality is deteriorated in continuous issuance at high speed.

Therefore, the present invention provides a thermal printer capable of setting the applied voltage in consideration of both the temperature of the thermal head and the temperature of the paper in continuous printing at high speed, and thus maintaining uniform print quality. To aim.

[0007]

SUMMARY OF THE INVENTION According to the present invention, a thermal head is provided, and the temperature of the thermal head is detected in a thermal printer that controls the voltage applied to the thermal head to print predetermined print information on a print medium. Head temperature detecting means, applied voltage setting means for setting an applied voltage to be applied to the thermal head based on temperature data detected by the head temperature detecting means, etc., and set by the applied voltage setting means during continuous printing of print media. The applied voltage is corrected based on a correction value preset according to the number of printed sheets and the printing rate, and the corrected applied voltage is set in place of the applied voltage set by the applied voltage setting means. A voltage setting means and a head voltage applying means for applying the set applied voltage to the thermal head are provided.

[0008]

In the present invention having such a structure, the temperature of the thermal head is detected by the head temperature detecting means.
The applied voltage to be applied to the thermal head is set by the applied voltage setting means based on the temperature data and the like detected by the head temperature detecting means. The applied voltage set by the head voltage applying means is applied to the thermal head, and the thermal head prints predetermined print information on the print medium.

Further, when the print medium is continuously issued, the applied voltage set by the applied voltage setting means on the basis of the temperature data obtained by the head temperature detecting means is corrected by the correction applied voltage setting means and the number of printed sheets and printing are performed. It is corrected based on a correction value set in advance according to the rate, and the corrected applied voltage is set instead of the applied voltage set by the applied voltage setting means. Then, the head voltage applying means applies the set applied voltage to the thermal head, and the thermal head prints predetermined print information on the print medium.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 is a CPU (central processing unit) that constitutes the main body of the control unit. This CP
ROM storing program data for processing performed by U1
(Read only memory) 2, RAM in which areas of various memories used when the CPU 1 performs processing are formed
A (random access memory) 3 and a communication I / F (interface) 4 connected to a host computer via a line are connected to the CPU 1 via a system bus 5.

Further, a keyboard controller 7 for controlling the keyboard 6 to which various data are input, a head controller 9 for controlling the thermal head 8, a motor controller 11 for controlling a stepping motor 10 as a drive source for conveying paper, and the like. An I / O (input / outpu) for inputting temperature data output from a temperature sensor 12 as a head temperature detecting means for detecting the temperature of the thermal head 8.
t) Port 13 is also connected to the C via the system bus 5.
It is connected to PU1.

As shown in FIG. 2, the RAM 3 further includes direct print or transfer print, a head resistance rank (rank of resistance value of the heating resistor of the thermal head 8),
A temperature table 3a, in which a table set according to the temperature of the thermal head 8 is provided for each printing speed,
As shown in FIG. 3, the correction rank table 3b in which the correction rank is set according to the ambient temperature, the printing rate, and the printing speed, whether it is direct printing or transfer printing, and as shown in FIG. Correction values C1, C2, ...
There is provided a correction value table 3c in which the numerical value of is set according to the correction rank. FIG. 5 shows the flow of the print control process performed by the CPU 1.

First, the temperature sensor 12 reads temperature (head temperature) data T0 of the thermal head 8, and the read head temperature data T0 and various preset conditions (print speed, direct printing or transfer printing, head The applied voltage data V0 to the thermal head 8 is read from the temperature table 3a according to the resistance rank. (Applied voltage setting means)

Next, it is determined whether or not continuous issuance in which the number of sheets to be issued is designated in the print setting. If it is not continuous issuance in which the number of sheets to be issued is specified in the print setting, a voltage is applied to the thermal head 8 by the applied voltage data V0 read from the temperature table 3a (head voltage applying means) to output print data, and 1 Prints and issues one sheet of label. Then, the print control process is ended.

Further, in the case of continuous issuance in which the number of issued sheets is specified in the print setting, first, the correction value is set to 0, the variable a is set to 1, and the issued number of sheets i is set to 0.
Various preset conditions (direct printing or transfer printing,
The correction rank is read from the correction rank table 3b and set according to the ambient temperature, print ratio, print speed).

Next, as step 1 (ST1), the head temperature data T1 is read again by the temperature sensor 12.
The read head temperature data T1 and the applied voltage data V1 to the thermal head are read from the temperature table 3a according to the various conditions described above.

Next, it is confirmed whether or not the issued number i is equal to the correction set number na (for example, na = 100 × a).
When the issued sheet number i is equal to the correction set sheet number na, the numerical value of the correction value Ca is read from the correction value table 3c and set by the correction rank set by reading from the correction rank table 3b, and +1 is added to the variable a. Perform processing.

Next, the applied voltage data V1 read from the temperature table 3a is added with the numerical value of the correction value Ca set and read to correct the applied voltage (corrected applied voltage setting means), and the corrected applied voltage is applied. A voltage is applied to the thermal head 8 according to the voltage V data (head voltage applying means), and print data is output to print one label.

When this print issuance is completed, the number of issued sheets i is incremented by +1 to determine whether the number of issued sheets i is equal to the number of issued sheets N specified in the print setting. If the issued number i is not equal to the designated number N,
The process returns to the above-mentioned step 1 again,
If the number of issued sheets i is equal to the designated number of sheets N to be issued, the print control process is ended.

In this embodiment having such a structure, the temperature of the thermal head 8 is detected by the temperature sensor 12, and the head temperature data T0 obtained by this detection and various preset conditions (printing speed, direct printing) Temperature table 3 depending on whether it is transfer printing or head resistance rank)
The applied voltage data V0 is read from a. If the printing is not continuous, printing is performed by applying a voltage to the thermal head 8 according to the read applied voltage data V0.

In the case of continuous issuance, the number of sheets to be issued is designated in advance, the correction rank is read from the correction rank table 3b according to preset conditions (direct printing or transfer printing, ambient temperature, printing rate, printing speed), and this reading is performed. The corrected correction rank is set.

The temperature of the thermal head 8 is detected by the temperature sensor 12 every time one sheet is issued, and the head temperature data T1 obtained by the detection is read. The applied voltage data V1 is read from the temperature table 3a according to the head temperature data T1 and the various conditions described above.

On the other hand, the value of the correction value Ca set for every 100 issued sheets, that is, the correction set number na, is corrected by the correction rank table 3c.
Read from and set. The numerical value of the set correction value Ca is added to each print voltage data V1 for correction, and a voltage is applied to the thermal head 8 by the corrected applied voltage data V to issue print.

For example, as shown in FIG. 6A, the temperature of the thermal head 8 rises according to the number of issued sheets. Therefore,
As shown in FIG. 6B, the graph A of the applied voltage data based on the head temperature data from the temperature sensor 12 is read from the correction value table 3c for every 100, 200, ... The set correction values C1, C2,
The numerical value of ... Is added to each applied voltage data of the graph A to perform the correction. Graph B of the corrected applied voltage data
As a result, a voltage is applied to the thermal head 8.

As described above, according to the present embodiment, the correction rank is set from the correction rank table 3b according to the conditions of the direct printing or the transfer printing, the ambient temperature, the printing rate, and the printing speed. Correction value table 3
Correction values C1 and C set for every 100 issued sheets from c
The numerical values of 2, ... Are read and set. The applied voltage data V1 read from the head temperature data and the like can be corrected by the numerical values of the set correction values C1, C2, .... Therefore, it is possible to perform the correction in consideration of the temperature difference between the head temperature rise and the paper temperature according to the number of issued sheets, and the voltage is applied to the thermal head 8 by the corrected applied voltage data V, so that the print quality is improved. Can be maintained uniformly.

Further, as shown in the graph of the head temperature with respect to the number of printed sheets according to the printing speed of FIG. Further, as shown in the graph of the head temperature with respect to the number of printed sheets according to the ambient temperature in FIG.
Graph H of FIG. 7 and Graph I of ambient temperature 5 ° C.
As shown in the graph (c) of the head temperature with respect to the number of printed sheets according to the print rate, the graph J of the print rate of 30%, the print rate of 2
There is a difference in the temperature rise of the thermal head 8 between the graph K of 0% and the graph L of the printing rate of 10%. However, according to the present embodiment, the printing speed from the correction rank table 3b
By the correction rank that can be read according to the ambient temperature and the printing rate,
Since the values of the correction values C1, C2, ... Of the correction value table 3c are set, the applied voltage can be corrected in consideration of the printing speed, the ambient temperature, and the printing rate. The effect can be obtained. In addition, the printing examples of the printing rates of about 10%, about 20% and about 30% are shown in FIG.
It shows in (a), FIG.8 (b), and FIG.8 (c).

[0028]

As described in detail above, according to the present invention,
In continuous printing at high speed, the applied voltage can be set in consideration of both the temperature of the thermal head and the temperature of the paper, and therefore a thermal printer can be provided which can maintain uniform print quality.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of essential parts of an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a temperature table of the same embodiment.

FIG. 3 is a diagram showing a configuration of a correction rank table of the same embodiment.

FIG. 4 is a diagram showing a configuration of a correction value table of the same embodiment.

FIG. 5 is a diagram showing a flow of print control processing of the embodiment.

FIG. 6 is a diagram showing an example of a graph of a head temperature with respect to the number of printed sheets and a graph of a head applied voltage with respect to the number of printed sheets in the embodiment.

FIG. 7 is a diagram showing an example of a graph of head temperature with respect to the number of printed sheets according to print speed, ambient temperature, and print rate.

FIG. 8 is a diagram showing a printing example for explaining a printing rate.

[Explanation of symbols]

1 ... CPU, 3a ... Temperature table, 3b ... Correction rank table, 3c ... Correction value table, 8 ... Thermal head,
12 ... Temperature sensor.

Claims (1)

[Claims] 1. A thermal printer which is provided with a thermal head and controls a voltage applied to the thermal head to print predetermined print information on a print medium, and a head temperature detecting means for detecting a temperature of the thermal head; An applied voltage setting means for setting an applied voltage to be applied to the thermal head based on temperature data detected by the head temperature detecting means, and an applied voltage set by the applied voltage setting means at the time of continuously issuing the print medium. A correction applied voltage setting means for correcting based on a correction value set in advance according to the number of issued sheets and the printing rate, and setting the corrected applied voltage in place of the applied voltage set by the applied voltage setting means. A head voltage applying means for applying a set applied voltage to the thermal head. Linta.