JPH10278333A - Thermal printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To preserve a temperature control table optimized over a range of temperature by measuring the temperature of a thermal head, storing a temperature control data corresponding to the print characteristics, reading out a temperature control data corresponding to the value of a temperature sensor from the temperature control table and controlling a thermal head. SOLUTION: The thermal printer comprises a temperature sensor 4 for measuring the temperature of a thermal head 3, a temperature control table 1 storing a temperature control data for the thermal head 3 corresponding to the print characteristics, and a control module 5. The control module 5 reads in current temperature of the thermal head 3 through a temperature sensor 4 mounted thereon, takes out the temperature control data of an optimal print pulse corresponding to the temperature read out from the temperature control table 1 and applies the data to the thermal head. According to the arrangement, only an optimal temperature control table 1 can be held in a mounted thermal head and the temperature control table corresponding to unnecessary head rank can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal printer, and more particularly to a thermal printer for controlling the temperature of a thermal head during printing.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing an example of the configuration of a conventional thermal printer disclosed in, for example, JP-A-3-96359.

Referring to FIG. 3, an optimal gradation table immediately before printing is written from a CPU 11 into a RAM 12, and a thermal head driving circuit 16 is operated based on the table data and the quantized image data to operate the thermal head driving circuit 16. A print image of a desired density is obtained by performing on / off control of the resistor of the head 17 and control of the energization time.

The gradation table may deviate from an optimal state due to a change in conditions such as a thermal head temperature during printing.
By rewriting the gradation table in the RAM 12 based on the instruction from the CPU 11, the gradation data optimal for the condition such as the temperature is always held, and the gradation data is output and output irrespective of the condition change. It is possible to print a print image of a density.

[0005]

The problem with the conventional thermal printer is that the table (one optimal gradation table) is rewritten when the optimum condition is deviated due to a change in conditions such as the temperature of the thermal head during printing. It must be. Since the temperature condition of the thermal head frequently changes during printing, the table is frequently rewritten during printing. Also, since the thermal head cools down while the table is being rewritten, it is highly likely that the rewritten table is no longer optimal when printing is attempted after rewriting the table.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermal printer in which an optimized temperature control table for a range of changing temperatures is stored in a rewritable nonvolatile memory in order to solve this problem. .

[0007]

SUMMARY OF THE INVENTION A thermal printer according to the present invention includes a thermal head having a plurality of heating elements for generating heat in accordance with print data, a temperature sensor for measuring the temperature of the thermal head, and a thermal head print. A temperature control table that stores temperature control data for the thermal head according to characteristics; and a control module that reads the temperature control data corresponding to the value of the temperature sensor from the temperature control table and controls the thermal head. .

Further, the thermal printer of the present invention includes the temperature control table for storing the temperature control data indicating a pulse width or a pulse height applied to the thermal head corresponding to the temperature of the thermal head.

Further, the thermal printer according to the present invention includes the temperature control table arranged on a rewritable nonvolatile memory.

Further, the thermal printer of the present invention includes a download control module for downloading the temperature control data corresponding to the thermal head from the host device to the temperature control table.

[0011]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. Referring to FIG. 1, a thermal printer according to this embodiment includes a thermal head 3 having a plurality of heating elements that generate heat in accordance with print data, a temperature sensor 4 for measuring the temperature of the thermal head 3, and a thermal head. A temperature control table 1 for storing temperature control data for the thermal head according to the printing characteristics and a control module 5 for reading the temperature control data corresponding to the value of the temperature sensor 4 from the temperature control table 1 and controlling the thermal head 3. Prepare. Further, the temperature control table 1 stores temperature control data indicating a pulse width or a pulse height applied to the thermal head 3 corresponding to the temperature of the thermal head 3. Further, this temperature control table is arranged on a rewritable nonvolatile memory. The thermal printer further includes a download control module 2 that downloads temperature control data corresponding to the thermal head 3 from the host device 6 to the temperature control table 1.

FIG. 2 is a configuration diagram showing an example of the temperature control table 1 according to this embodiment. The temperature control table 1 records the applied pulse width or applied pulse height corresponding to the temperatures T1, T2,..., Tn of the thermal head 3. Further, a checksum for checking the validity of the contents of the data stored in the temperature control table 1 is added to the last position of the temperature control table 1.

The operator downloads the temperature control data corresponding to the resistance rank of the attached thermal head (variation in the resistance value during manufacture) from the host device 6 as necessary (for example, when the thermal head is replaced). . The downloaded optimal temperature control data is written by the download control module 2 into the temperature control table 1 arranged on a rewritable nonvolatile memory. At this time, the download control module 2 calculates the checksum of the received data, compares it with the checksum added to the temperature control data received from the host device 6, and confirms that there is no error in the received temperature control data. It is written after confirmation. If the temperature control table 1 has already been downloaded when the power of the printer is turned on, a checksum of the written temperature control data is calculated.
By comparing with the checksum added to the temperature control table 1, it is confirmed that the temperature control table 1 is not broken.

The control module 5 reads the current temperature of the thermal head 3 by the temperature sensor 4 mounted on the thermal head 3, and determines the optimum applied pulse width or pulse height corresponding to the temperature read from the temperature control table 1. Is taken out and applied to the thermal head.

With the above configuration and control, only the temperature control table 1 optimal for the mounted thermal head 3 can be held in the printer, and unnecessary temperature control tables corresponding to the head rank can be reduced. In addition, it is possible to maintain a temperature control table that is optimally corrected even for variations in resistance values that occur during the manufacture of the mounted thermal head, thereby preventing variations in print density in heads of the same rank. Becomes possible.

[0017]

The first effect is that the cost of the printer can be reduced. The reason is that since only the necessary temperature control table of the thermal head is held in the printer, there is no need to mount an unnecessary storage module.

The second effect is that an optimum printing result can be obtained for the mounted thermal head. The reason is that the data of the temperature control table can be finely adjusted so as to be optimal for the resistance rank of the mounted thermal head.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating an example of a temperature control table according to the embodiment;

FIG. 3 is a block diagram illustrating an example of a configuration of a conventional thermal printer.

[Explanation of symbols]

 1 Temperature control table 2 Download control module 3 Thermal head 4 Temperature sensor 5 Control module 6 Host device

Claims (4)

[Claims] 1. A thermal head having a plurality of heating elements for generating heat in accordance with print data, a temperature sensor for measuring a temperature of the thermal head, and a temperature control for the thermal head according to the print characteristics of the thermal head A thermal printer, comprising: a temperature control table that stores data; and a control module that reads the temperature control data corresponding to the value of the temperature sensor from the temperature control table and controls the thermal head. 2. The temperature control table according to claim 1, further comprising: the temperature control table storing the temperature control data indicating a pulse width or a pulse height applied to the thermal head corresponding to the temperature of the thermal head. Thermal printer. 3. The thermal printer according to claim 1, further comprising the temperature control table arranged on a rewritable nonvolatile memory. 4. The thermal printer according to claim 3, further comprising a download control module that downloads the temperature control data corresponding to the thermal head from a host device to the temperature control table.