JP2008162107A - Thermal printer and printing controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a quality of printing by increasing and decreasing an applied energy standardly established with the ratio according to the percentage of the number of printing pixels which accounts for in a fixed area. <P>SOLUTION: A thermal printer is equipped with a pixel number detection means for detecting the percentage of the number of printing pixels which accounts for in the fixed area of the printing data which is going to be printed, a calculation means which computes the energy amount applied to a thermal printing head 104 from the percentage of the printing pixels number detected by the pixel number detection means and the temperature of the thermal printing head 104 detected by the temperature detection means and a driving means for actuating the heating element of the thermal printing head 104 with applied energy computed by the calculation means. The heating element of the thermal printing head 104 is actuated by increasing and decreasing the amount of applied energy according to the percentage of the printing pixel number detected by the pixel number detection means and the temperature of the thermal printing head 104 detected by the temperature detection means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a printer using a thermal print head, and in particular, detects the ratio of the number of print pixels in a predetermined area of print data, and generates heat of the thermal print head according to the detected ratio of the number of print pixels. The present invention relates to a thermal printer in which printing quality is improved by adjusting applied energy for driving an element and a printing control apparatus thereof.

  In general, a thermal printer mechanism is often employed as a printing mechanism used in equipment having a scanner function, particularly a facsimile machine or a home telephone having a facsimile function.

  Usually, a thermal printer is provided with a thermal print head for a plurality of heating elements arranged in a line, and an ink ribbon is generated by applying a pulse signal to each of the plurality of heating elements to generate heat. A configuration is adopted in which printing is performed by transferring ink from recording paper to recording paper. In a printer using such a thermal print head, the output value of a thermistor attached to the head itself is read, the current temperature of the head itself is detected, and the applied energy suitable for the temperature is controlled. .

  If the amount of energy applied to each heating element of the thermal print head is too small, the ink will not melt sufficiently and the print will be faint. Conversely, if the amount of energy applied to each heating element is too large, the ink will melt excessively and the print will be crushed. Also, when the same applied energy is applied at the same head temperature, thick lines and thick characters are clearly printed, but thin lines and thin characters do not sufficiently penetrate the applied energy, and the printing is partially blurred. Or

  Therefore, when the head temperature of the thermal print head or the ambient temperature is low, a large amount of energy is required to melt the ink. When the head temperature of the thermal print head is high, sufficient energy is given to the ink even if the applied energy is small. Therefore, the applied energy is set and adjusted in several steps according to the temperature of the print head.

  Also, if the interval between the printed lines is long, or if there are many blank lines without print dots between the lines with print dots, the head temperature of the thermal print head will change, so depending on the time interval of paper feed (print pause time) Set and adjust the standard energy to be applied in several steps. Adjustment of applied energy of a thermal print head in a general thermal printer is performed by a combination thereof.

  For example, in Patent Document 1 (Japanese Patent Laid-Open No. 6-106766), printing is performed by performing energization control in consideration of not only the head temperature during image printing but also the heat storage state of each heating resistor. A technique capable of preventing the occurrence of density unevenness is disclosed.

  The technique disclosed in Patent Document 1 includes temperature detecting means for detecting the temperature of a thermal print head, and a main pulse signal having energization power corresponding to gradation data is applied to each heating resistor to form an image on a recording medium. And a preliminary pulse signal having a temperature detected by the temperature detecting means and energization power corresponding to the gradation data between the printing means for printing the image of each line by the printing means Preheating means for energizing each heating resistor to preheat each heating resistor to a predetermined temperature that does not lead to printing, and each heating resistor has a predetermined temperature at the start of image printing of each line. It is comprised so that it may be maintained.

  With this configuration, it is possible to accurately grasp the heat storage state of each heating resistor during image printing, and it is possible to reproduce a high-quality image that does not cause uneven printing density.

  Further, in the following Patent Document 2 (Japanese Patent Laid-Open No. 11-235840), the number of basic applied pulses corresponding to the printing data determined based on the sensitivity curve is set based on the heat storage information indicating the heat storage state of the head. A technique for correcting based on the sensitivity curve based on the determined number of reference pulses is disclosed.

The technique disclosed in Patent Document 2 includes basic pulse determining means for determining a basic applied pulse corresponding to printing data based on basic characteristic information indicating a relationship between basic printing density data and basic applied pulse, thermal printing, A reference pulse determining means for determining a reference pulse corresponding to a predetermined printing density based on livestock heat information indicating a heat storage state of the head and a basic application pulse determined by the basic pulse determining means are determined by the reference pulse determining means. The applied pulse correction means corrects by the reference pulse. With such a configuration, phenomena such as density unevenness, tailing, or blurring of lines due to changes in the state of heat of the thermal print head when printing is performed can be suppressed, and a high-quality printed image can be obtained.
JP-A-6-106766 (paragraph [0009], FIG. 1) Japanese Patent Laid-Open No. 11-235840 (paragraph [0006], FIG. 1)

  As described above, in the thermal printing printing technique disclosed in Patent Documents 1 and 2, the printing density unevenness can be suppressed by correcting the applied pulse in accordance with the thermal state of the thermal print head. The idea is made.

  However, in such a method, the standard applied energy set in advance is only selected depending on the combination of the head temperature and the print paper feed time, and the print quality may not be sufficiently ensured. For example, when a thin line or a fine character is included, sufficient applied energy does not penetrate into the portion and blurring may occur.

  From this phenomenon, it can be seen that when the actual number of printed dots in one line is small, the amount of energy is insufficient with the standard applied energy set above. That is, it is necessary to set the applied energy amount in consideration of the actual number of print dots.

  The inventor of the present application has conducted various studies to solve the above-described problems, and as a result, the ratio of the number of print pixels occupying the standard applied energy obtained by the control method as described above in a certain area, that is, The above problem can be solved by increasing / decreasing the ratio according to the number of print dots (number of black pixels) in one line and thereby applying the optimum energy according to the actual print data. With this in mind, the present invention has been completed.

  That is, the present invention aims to solve the above-mentioned problems, and is standard at a ratio according to the ratio of the number of print pixels occupying a certain area, for example, the number of print dots (number of black pixels) in one line. It is an object of the present invention to provide a thermal printer and a print control device that improve the print quality by increasing or decreasing the applied energy set in (1).

In order to solve the above-mentioned problem, the invention according to claim 1 of the present application includes a thermal print head having a plurality of heating elements arranged in a row, and a temperature detection means for detecting the temperature of the thermal print head. In the thermal printer that drives the thermal print head with an applied energy amount corresponding to the temperature range of the thermal print head detected by the temperature detecting means, the number of print pixels that occupy in a certain area of print data to be printed from now on A number-of-pixels detecting means for detecting the ratio of the print, the application to the thermal print head based on the ratio of the number of print pixels detected by the number-of-pixels detection means and the temperature of the thermal print head detected by the temperature detection means Calculating means for calculating the amount of energy, and thermal printing head with the applied energy calculated by the calculating means; And a driving means for driving the heat generating elements, said drive means and drives the heating elements of the thermal print head at an applied energy said calculating means is calculated.
The invention according to claim 2 of the present application is the thermal printer according to claim 1, wherein the thermal printer further includes a ratio of the number of print pixels, a temperature of the thermal print head, and an optimum energy applied to the thermal print head. Data storage means for storing the correlation data, and the calculation means is based on the ratio of the number of print pixels detected by the pixel number detection means and the temperature of the thermal print head detected by the temperature detection means. The optimum amount of applied energy is read from the data storage means, and the amount of energy applied to the thermal print head is calculated.

  The invention according to claim 3 of the present application is characterized in that, in the thermal printer according to claim 1 or claim 3, the ratio of the number of print pixels in the certain area is the number of print dots in one line. To do.

  The invention according to claim 4 of the present application includes a thermal print head having a plurality of heating elements arranged in a line, and a temperature detection means for detecting the temperature of the thermal print head, and the temperature detection means. In a print control device that performs print control of a thermal printer that drives the thermal print head with an applied energy amount corresponding to the temperature range of the thermal print head detected by the printer, the print data that occupies a certain area of print data to be printed from now on A pixel number detecting means for detecting a ratio of the number of pixels, a print pixel number ratio detected by the pixel number detecting means, and a temperature of the thermal print head detected by the temperature detecting means to the thermal print head. A calculating means for calculating the amount of applied energy, and the applied energy calculated by the calculating means Comprising a drive means for driving the heating elements of the shaped heads, wherein the drive means and drives the heating elements of the thermal print head at an applied energy said calculating means is calculated.

  The invention according to claim 5 of the present application is the print control device according to claim 4, wherein the print control device further includes a ratio of the number of print pixels, a temperature of the thermal print head, and an optimum application to the thermal print head. Data storage means for storing correlation data with energy, wherein the calculation means is based on the ratio of the number of print pixels detected by the pixel number detection means and the temperature of the thermal print head detected by the temperature detection means. Then, the optimum amount of energy applied is read from the data storage means to calculate the amount of energy applied to the thermal print head.

  The invention according to claim 6 of the present application is the print control device according to claim 4 or 5, wherein the ratio of the number of print pixels in the certain area is the number of print dots in one line. And

  In the inventions according to claims 1 and 4, the thermal printer and the print control device thereof include a pixel number detection means for detecting a ratio of the number of print pixels in a predetermined area of print data to be printed, and a pixel Calculating means for calculating the amount of energy applied to the thermal print head based on the ratio of the number of print pixels detected by the number detection means and the temperature of the thermal print head detected by the temperature detection means; and the calculation means Driving means for driving the heating element of the thermal print head with the calculated applied energy, and the driving means drives the heating element of the thermal print head with the applied energy calculated by the calculation means.

  According to such a configuration, the optimum energy according to the actual print data is applied to the thermal print head, so that blurring of fine lines and the like can be relatively improved, so that the print quality can be remarkably improved. become.

  In the invention according to claims 2 and 5, in the thermal printer and the print control device according to claims 1 and 4, the ratio of the number of print pixels, the temperature of the thermal print head, and the optimum for the thermal print head. Data storage means for storing correlation data with various applied energies, and the calculating means includes a ratio of the number of print pixels detected by the pixel number detection means and a temperature of the thermal print head detected by the temperature detection means. Based on the above, the optimum amount of applied energy is read from the data storage means, and the amount of energy applied to the thermal print head is calculated.

  According to such a configuration, the optimum energy according to the actual print data is applied to the thermal print head, so that blurring of fine lines and the like can be relatively improved, so that the print quality can be remarkably improved. become.

  In the invention according to claims 3 and 6, in the thermal printer according to claim 1 or claim 2, claim 4 or claim 5 and its print control device, the ratio of the number of print pixels occupying in the predetermined area Is the number of printed dots in one line.

  According to such a configuration, the applied energy is increased / decreased at a ratio corresponding to the number of print dots (number of black pixels) in one line, so that optimum energy corresponding to actual print data is applied to the thermal print head. As a result, blurring of fine lines and the like can be improved relatively, and the print quality can be remarkably improved.

  Hereinafter, specific examples of the present invention will be described in detail with reference to examples and drawings. However, the embodiments shown below exemplify a thermal printer and a print control device for embodying the technical idea of the present invention, and are intended to specify the present invention as the thermal printer and the print control device. However, the present invention is equally applicable to thermal printers and print control apparatuses according to other embodiments included in the claims.

  FIG. 1 is a schematic diagram showing the configuration of a thermal printer 100 equipped with a scanner according to an embodiment of the present invention. The thermal printer 100 includes an ink ribbon 101, a supply-side ink ribbon 102, a take-up-side ink ribbon 103, a thermal print head 104, a printer roller 105, a paper feed roller 107 for a recording paper 106, a discharge roller 108, and a paper feed roller for a document 109. 110, a contact sensor 111, a scanner roller 112, and the like.

  The ink ribbon 101 is pulled out from the supply-side ink ribbon 102 and passes between the thermal print head 104 and the printer roller 105, and then taken up by the take-up side ink ribbon 103.

  The thermal print head 104 is arranged in the width direction (main scanning direction) orthogonal to the conveyance direction (sub-scanning direction) of the recording paper 106, and has a plurality of heating element elements for recording an image for one line on the recording paper 106. Arranged in the main scanning direction. The element is heated by energizing the heating element of the thermal print head 104 (application of a pulse signal), and the ink on the ink ribbon 101 is melted and transferred to the recording paper 106.

  The recording paper 106 is conveyed by the recording paper feed roller 107, passes between the ink ribbon 101 and the printer roller 105, and then discharged out of the thermal printer 100 by the discharge roller 108.

  The printer roller 105 is disposed to face the thermal print head 104, conveys the recording paper 106, and presses the thermal print head 104 and the ink ribbon 101 with a predetermined pressure toward the thermal print head 104.

  Although not shown, the thermal print head 104 is provided with a temperature detection element (for example, a thermistor) as temperature detection means for detecting the temperature.

  The contact sensor 111 is arranged in the width direction (main scanning direction) orthogonal to the conveyance direction (sub-scanning direction) of the document 109, and has a plurality of reading elements for reading an image image recorded on the document 109 as a scanner function. Are juxtaposed in the main scanning direction.

  The document 109 is conveyed by the document feed roller 110, passes between the contact sensor 111 and the scanner roller 112, and then is discharged out of the thermal printer 100.

  The scanner roller 112 is disposed so as to face the contact sensor 111, rotates at a predetermined image reading speed while holding the document 109 at a predetermined position, and conveys the document 109 in the direction of the discharge port of the document 109.

  FIG. 2 is a block diagram showing the configuration of the control system circuit of the thermal printer 100 equipped with the scanner according to the embodiment of the present invention.

  The thermal printer 100 includes a printer control engine 200, a program memory 201, an image storage memory 202, a printer control motor 203, a scanner control motor 204, and the like.

  Although this embodiment shows a thermal printer equipped with a scanner, it may be a printer system including a thermal printer and an external scanner device. If the thermal printer does not have a scanner function, the thermal printer is closely attached. It is not necessary to provide the sensor 111 or the scanner control motor.

  The printer control engine 200 includes a CPU 205 that controls the operation of each unit according to a control program stored in the program memory 201, a print control unit 206 that controls the thermal print head 104, an image reading control unit 207 that controls the contact sensor 111, and a printer. The motor control unit 208 controls the control motor 203 and the scanner control motor 204.

  The program memory 201 stores a control program for controlling the operation of each unit, and stores correlation data between the ratio of the number of print pixels, the temperature of the thermal print head 104, and the optimum applied energy to the thermal print head 104. A table of optimum applied energy for the thermal print head as data storage means is stored.

  FIG. 3 is a diagram showing an example of a table of optimum applied energy for the thermal print head according to the embodiment of the present invention.

  The table example of FIG. 3 is the correlation data of the applied energy with respect to the black pixel rate in one line and the thermal print head temperature. The applied energy standard value of each head temperature is set when the black pixel rate in one line is 50%. An example is shown in which an increase / decrease rate from a standard value corresponding to the ratio of the pixel rate is set corresponding to each head temperature.

  For example, when the black pixel rate is 30% at a head temperature of 40 ° C., it is 10% higher than the applied energy standard value at a head temperature of 40 ° C., and when the black pixel rate is 30% at a head temperature of 70 ° C. It is set to 5% higher than the applied energy standard value at 70 ° C. The applied energy standard value is 0 ° C. standard value> 10 ° C. standard value>...> 60 ° C. standard value> 70 ° C. standard value, and this table is stored in the program memory 201.

  The image storage memory 202 stores print data to be printed on the recording paper 106 by the thermal print head 104 controlled by the print control unit 206, and from the document 109 by the contact sensor 11 controlled by the image reading control unit 207. The read image data is stored.

  The print control unit 206 supplies energy applied to the thermal print head 104 based on the print data read from the image storage memory 202 by the CPU 205 and corresponds to an optimum application energy table stored in the program memory 201. To supply a control signal for correcting the applied energy. Further, the image reading control unit 207 supplies a control signal for performing drive control of the contact sensor 11.

  The motor control unit 208 controls the rotation speed of the printer control motor 203 such as the printer roller 105 according to the printing time required to print the print data for one line from the CPU 205 to control the recording paper 106 and the ink ribbon 101. Control the conveyance speed. Further, the motor control unit 208 controls the rotation speed of the scanner control motor 204 such as the scanner roller 112 according to the reading time required for reading the image data for one line of the document 109 by the contact sensor 111, thereby controlling the document 109. Control the conveyance speed.

  FIG. 4 is a schematic flowchart showing control in the thermal printer 100 equipped with the scanner according to the embodiment of the present invention.

  As shown in FIG. 4, when a control signal is output from the CPU 205 to the contact sensor 111, the contact sensor 111 reads image data from the document 109 according to the control signal and transfers it to the CPU 205. The image data transferred to the CPU 205 is stored in the image storage memory 202.

  The image data stored in the image storage memory 202 for printing is read in a predetermined unit such as one page or half page, and is bitmap-developed in a VRAM (not shown). The print control unit 206 drives each heating element of the thermal print head based on the data developed in the VRAM. When the bit map is expanded to the VRAM, the number of black pixels in one line is counted to detect the black pixel ratio after one line.

  That is, the CPU 205 reads the image data from the image storage memory 202 and detects the ratio of black pixels in one line when developing the bitmap in the VRAM, and detects the thermal detected by the thermistor provided in the thermal print head 104. The optimum applied energy is read from the program memory 201 with reference to a table showing the relationship between the temperature of the print head 104, the black pixel ratio, and the optimum applied energy, and is output to the print control unit 206 together with the print data. Based on this, 206 drives the thermal print head 104.

  As a result, the thermal print head 104 causes the print data for one line from the CPU 205 to generate heat on each heating element by energizing the optimum applied energy, and prints the print data for each line on the recording paper 106 according to the print data. Do.

  FIG. 5 is a time chart showing an example of print strobe signal control in the present invention.

  As shown in FIG. 5, when print data a to d for one line read from the image storage memory 202 by the CPU 205 are transferred to the thermal print head 104 and a latch signal is output, the print control unit 206 outputs the latch signal. Strobe signals stb1 to stb4 are output based on the control signal.

  Then, the thermal print head 104 divides the print data for one line into four according to the strobe signals stb1 to stb4 and proceeds to the printing operation, and prints the next second line b at the timing when the strobe signal stb4 for the first line a is output. Data is transferred to the thermal print head 104. The same applies to the print data for the third line c and the print data for the fourth line d.

  As described above, according to the thermal printer according to the present invention, since the optimum energy corresponding to the actual print data is applied to the thermal print head, blurring of fine lines and the like can be relatively improved, so the print quality can be improved. It can be significantly improved.

It is the schematic which shows the structure of the thermal printer carrying the scanner concerning the Example of this invention. It is a block diagram which shows the structure of the control system circuit of the thermal printer carrying the scanner concerning the Example of this invention. It is a figure which shows an example of the table of the optimal applied energy with respect to the thermal print head concerning the Example of this invention. It is a schematic flowchart which shows the control in the thermal printer carrying the scanner concerning the Example of this invention. It is a time chart which shows an example of the printing strobe signal control in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Thermal printer 101 ... Ink ribbon 102 ... Supply side ink ribbon 103 ... Winding side ink ribbon 104 ... Thermal print head 105 ... Printer roller 106 ... ... Recording paper 107 ...... Recording paper feeding roller 108 ...... Discharging roller 109 ...... Document 110 ...... Document feeding roller 111 ... Contact sensor 112 ...... Scanner Roller 200 ... Printer control engine 201 ... Program memory 202 ... Image storage memory 203 ... Printer control motor 204 ... Scanner control motor 205 ... CPU
206 ... Print control unit 207 ... Image reading control unit 208 ... Motor control unit

Claims (6)

A thermal print head having a plurality of heating elements arranged in a row, and a temperature detection means for detecting the temperature of the thermal print head, and according to the temperature range of the thermal print head detected by the temperature detection means In the thermal printer that drives the thermal print head with the amount of applied energy, a pixel number detecting means for detecting a ratio of the number of print pixels in a predetermined area of print data to be printed from now, and the pixel number detecting means Calculating means for calculating the amount of energy applied to the thermal print head based on the ratio of the number of printed pixels and the temperature of the thermal print head detected by the temperature detecting means; and the applied energy calculated by the calculating means Driving means for driving the heating element of the thermal print head, and the driving means Thermal printer characterized in that to drive the heating elements of the thermal print head at an applied energy said calculating means is calculated. The thermal printer further includes data storage means for storing correlation data among the ratio of the number of print pixels, the temperature of the thermal print head, and the optimum energy applied to the thermal print head, and the calculation means includes detecting the number of pixels. Based on the ratio of the number of print pixels detected by the means and the temperature of the thermal print head detected by the temperature detection means, an optimum amount of applied energy is read from the data storage means, and the amount of energy applied to the thermal print head The thermal printer according to claim 1, wherein the thermal printer is calculated. 3. The thermal printer according to claim 1, wherein a ratio of the number of print pixels in the certain area is the number of print dots in one line. A thermal print head having a plurality of heating elements arranged in a row, and a temperature detection means for detecting the temperature of the thermal print head, and according to the temperature range of the thermal print head detected by the temperature detection means In a print control apparatus for performing print control of a thermal printer that drives the thermal print head with an applied energy amount, a pixel number detection means for detecting a ratio of the number of print pixels in a predetermined area of print data to be printed from now on; Calculating means for calculating the amount of energy applied to the thermal print head based on the ratio of the number of print pixels detected by the pixel number detection means and the temperature of the thermal print head detected by the temperature detection means; Driving hand that drives the heating element of the thermal print head with the applied energy calculated by the calculating means If, wherein the drive means includes print control apparatus characterized by driving the heating elements of the thermal print head at an applied energy said calculating means is calculated.   The print control device further includes data storage means for storing correlation data among the ratio of the number of print pixels, the temperature of the thermal print head, and the optimum energy applied to the thermal print head, and the calculation means includes the number of pixels. Based on the ratio of the number of print pixels detected by the detection means and the temperature of the thermal print head detected by the temperature detection means, an optimum amount of applied energy is read from the data storage means to apply the energy to the thermal print head. The printing control apparatus according to claim 4, wherein the printing amount is calculated.   The print control apparatus according to claim 4 or 5, wherein the ratio of the number of print pixels in the certain area is the number of print dots in one line.

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