JP4580010B2 - Thermal printer - Google Patents

Description

The present invention is simultaneously directed to printable thermal printers on the surface and the back surface of the print medium.

  A double-sided thermal printer having two platen rollers and two thermal heads has been proposed as a thermal printer capable of simultaneously printing on both front and back sides of a thermal paper (see, for example, Patent Document 1).

In this type of conventional double-sided thermal printer, the first platen roller and the second platen roller are rotated at the same feed speed in synchronization with each other. As the thermal paper passes between the first platen roller and the first thermal head, printing is performed on one surface of the thermal paper by the first thermal head. Further, when the thermal paper passes between the second platen roller and the second thermal head, printing is performed on one surface of the thermal paper by the second thermal head.
Japanese Patent Laid-Open No. 11-286147

  As a thermal paper used in this type of thermal printer, a double-sided thermal paper in which a heat-sensitive layer is formed on both sides of a base paper is usually used. On the other hand, there is a single-sided thermal paper in which a heat-sensitive layer is formed only on one side of the base paper. The double-sided thermal paper and the single-sided thermal paper have almost no difference in appearance. For this reason, if the user accidentally sets a single-sided thermal paper in the double-sided thermal printer, the printed result will appear only on one side of the paper where the heat-sensitive layer is formed, even though double-sided printing is performed. That happened.

The present invention has been made in view of such circumstances, it is an object of providing a thermal printer which can perform double-sided printing only for double-sided thermal paper that the heat-sensitive layer is formed on both surfaces There is to do.

The present invention relates to a sheet conveying means for conveying one thermal sheet of a double-sided thermal sheet having a heat-sensitive layer formed on both sides and a single-sided thermal sheet having a heat-sensitive layer formed on either side, and a sheet conveying means. The first thermal head is disposed so as to be in contact with one surface of the thermal paper transported by the first and performing printing on the one surface, and is disposed so as to be in contact with the other surface of the thermal paper, and printing is performed on the other surface. A second thermal head for performing thermal recording, a paper discriminating unit for discriminating whether or not a thermal layer is formed on one side and the other side of the thermal paper, and one side and the other side of the thermal paper by the paper discriminating unit of the condition that the heat-sensitive layer is determined to have been formed on both sides of the surface, the printing on both sides of the thermal paper by operating the first thermal head and the second thermal head Pleased, on condition that the heat-sensitive layer is determined to have been formed, the heat-sensitive layer of the first thermal head and the second thermal head formed on one of one side or the other side of the thermal sheet A print control means for controlling the printing on one side which is determined that the thermal layer of the thermal paper is formed by operating the thermal head arranged so as to be in contact with the surface which is determined to be It is.

  According to the thermal printer of the present invention in which such means is provided, there is an effect that double-sided printing can be performed only on a double-sided thermal paper having a heat-sensitive layer formed on both sides.

  The best mode for carrying out the present invention will be described below with reference to the drawings. This embodiment is a case where the present invention is applied to a thermal printer 10 capable of printing on both sides of the thermal paper 1.

  FIG. 1 is a diagram schematically illustrating an outline of a printing mechanism unit in the thermal printer 10 according to the first embodiment. The thermal paper 1 wound in a roll shape is accommodated in a paper accommodating portion of a printer main body (not shown). Then, the leading end is pulled out from the paper storage portion and discharged from the paper discharge port of the printer main body to the outside.

  The printer main body is provided with a first thermal head 2 so as to be in contact with one surface of the thermal paper 1 pulled out from the paper accommodating portion (hereinafter, this surface is referred to as a front surface 1A). A first platen roller 3 is provided so as to face the first thermal head 2 with the thermal paper 1 interposed therebetween.

  Further, the second thermal head 4 is in contact with the other surface of the thermal paper 1 drawn out from the paper storage portion (hereinafter, this surface is referred to as the back surface 1B) on the upstream side of the first thermal head 2 in the paper feeding direction. Is provided. A second platen roller 5 is provided so as to face the second thermal head 4 with the thermal paper 1 interposed therebetween.

  Further, a cutter mechanism 6 for cutting the thermal paper 1 discharged from the paper discharge port is provided on the downstream side of the first thermal head 2 in the paper feeding direction.

  A first mark sensor 7A and a second mark sensor 7B are provided on the downstream side in the paper feeding direction from the first thermal head 2 and the upstream side from the cutter mechanism 6 so as to face each other with the thermal paper 1 interposed therebetween. It has been. The first mark sensor 7A detects a predetermined paper determination mark printed on the front surface 1A of the thermal paper 1, and the second mark sensor 7B determines a predetermined paper determination printed on the back surface 1B of the thermal paper 1. The mark is detected, and details will be described later.

  Each of the first thermal head 2 and the second thermal head 4 is a line thermal head in which a large number of heating elements are arranged in a row, and the arrangement direction of the heating elements is orthogonal to the conveyance direction of the thermal paper 1. Is attached to the printer body.

  The first platen roller 3 and the second platen roller 5 are formed in a cylindrical shape, and the rotation of a sheet feed motor 23 (to be described later) is transmitted by a power transmission mechanism (not shown) so as to rotate in the directions indicated by the arrows. . As the platen rollers 3 and 5 rotate, the thermal paper 1 drawn out from the paper storage unit is conveyed in the direction of the arrow shown in the figure, and is discharged to the outside from the paper discharge port. Here, the first platen roller 3 and the second platen roller 5 constitute a conveying unit.

  FIG. 2 is a block diagram showing a main configuration including the control circuit of the thermal printer 10. The thermal printer 10 includes a CPU (Central Processing Unit) 11 as a control unit body. The CPU 11 is connected to a ROM (Read Only Memory) 13, a RAM (Random Access Memory) 14, an I / O (Input / Output) port 15, and a communication interface 16 via a bus line 12 such as an address bus and a data bus. , The first and second motor drive circuits 17 and 18 and the first and second head drive circuits 19 and 20 are connected to form a control circuit. Driving power is supplied from the power supply circuit 21 to each part constituting the control circuit.

  A host device 30 is connected to the communication interface 16. The host device 30 generates print data in a timely manner and supplies the print data to the thermal printer 10 through the interface. Signals from various sensors such as the first mark sensor 7A and the second mark sensor 7B are input to the I / O port 15.

  The first motor drive circuit 17 controls on / off of a paper feed motor 22 that is a drive source of a transport unit that transports the thermal paper 1 in one direction. The second motor drive circuit 18 controls on / off of a cutter motor 23 that is a drive source of the cutter mechanism 6.

  The first head drive circuit 19 controls the printing operation of the first thermal head 2. The second head drive circuit 20 controls the printing operation of the second thermal head 4. The correspondence relationship between the first head drive circuit 19 and the first thermal head 2 is shown in the block diagram of FIG. The correspondence relationship between the second head drive circuit 20 and the second thermal head 4 is the same as this, and the description thereof is omitted here.

  The first thermal head 2 includes N (N is a plurality) heating elements arranged in a line, and a line thermal head main body 41 capable of printing one line data consisting of dots of the number of elements N at a time, and the above 1 A latch circuit 42 that latches line data for each line, and an energization control circuit that selectively energizes N heating elements constituting the line thermal head main body 41 according to the one line data latched by the latch circuit 42. 43.

  The first head drive circuit 19 takes in one line data for N dots sequentially input via the bus line 12 and outputs it to the latch circuit 42. The first head drive circuit 19 outputs the strobe signal STB to the latch circuit 42. And a function of outputting the enable signal ENB to the energization control circuit 43.

  The latch circuit 42 latches one line data output from the head drive circuit 19 at the timing when the strobe signal STB becomes active. The energization control circuit 43 energizes the heating element corresponding to the print dot in the one line data latched by the latch circuit 42 while the enable signal ENB is active.

  As shown in FIG. 4, the RAM 14 is expanded with a reception buffer 51 for storing print data received from the host device 30 and raster image data of print data to be printed on the front surface 1 </ b> A side of the thermal paper 1. A front image buffer 52 as a first image buffer to be stored; and a back image buffer 53 as a second image buffer in which raster image data of print data to be printed on the back surface 1B side of the thermal paper 1 is expanded and stored. Is formed.

  FIG. 5 schematically shows a cross-sectional structure of the thermal paper 1 that can be used in the thermal printer 10 having such a configuration. FIG. 2A shows a double-sided thermal paper P1 in which heat-sensitive layers 62 and 63 are formed on both the front and back sides of the base paper 61, respectively. FIG. 2B shows a single-sided thermal paper P2 corresponding to the surface in which the heat-sensitive layer 62 is formed only on the surface of the base paper 61. FIG. FIG. 4C shows a single-sided thermal paper P3 corresponding to the back surface in which the heat-sensitive layer 63 is formed only on the back surface of the base paper 61. FIG. The heat sensitive layers 62 and 63 are made of a material that develops a desired color such as black or red when heated to a predetermined temperature or higher. These thermal papers P1 to P3 are all housed in a paper housing portion of the printer body in a state of being wound in a roll shape so that the surface 1A faces inward as shown in FIG.

  The CPU 11 is configured to execute processing of a procedure shown in the flowchart of FIG. 7 in response to a power-on operation or a reset operation after paper replacement. First, as ST (step) 1, it is determined whether or not the thermal paper 1 is normally set.

  In the case of the thermal printer 10 according to the present embodiment, a user who needs to replace the thermal paper 1 opens the cover of the printer main body and accommodates the new paper 1 in the paper accommodating portion. When the leading edge of the sheet 1 passes between the second thermal head 4 and the second platen roller 5, and further passes between the first thermal head 2 and the first platen roller 3, the cover is closed. It has a structure. Therefore, a paper sensor is provided between the first thermal head 2 and the second thermal head 4, and the CPU 11 checks the paper sensor and determines that the paper is normally set when it is in the paper detection state. Such a paper sensor is well known.

  If it is determined that the paper 1 is set normally, the CPU 11 controls the paper feed motor 22 to feed the paper 1 by a predetermined amount f in ST2. The feed amount f is an amount substantially equal to the separation distance from the first thermal head 2 to the cutter 6.

  If the sheet 1 is fed by a predetermined amount f, the CPU 11 converts the print data of the sheet determination mark stored in the ROM 13 in advance as ST3 into dots and develops them in the front image buffer 52 and the back image buffer 53, respectively. Store. Then, the raster image data of the paper determination mark stored in the front image buffer 52 is output to the first head driving circuit 19 and printed on the front surface 1A of the paper 1 by the first thermal head 2. The raster image data of the paper determination mark stored in the back image buffer 53 is output to the second head drive circuit 20 and printed on the back surface 1B of the paper 1 by the second thermal head 4 (mark printing means).

  When the printing operation of the paper determination marks on both the front and back sides of the paper 1 is completed, the CPU 11 controls the paper feed motor 22 to feed the paper 1 by a predetermined amount h in ST4. The feed amount h is slightly longer than the distance from the second thermal head 2 to the cutter 6.

  An example of the state of the front surface 1A and the back surface 1B of the paper 1 at this time is shown in FIG. In the figure, an arrow 70 indicates the conveyance direction of the paper 1. An interval g indicates a separation distance between the first thermal head 2 and the second thermal head 4. When the sheet 1 is fed by a predetermined amount f in ST2, the first thermal head 2 comes into contact with the position indicated by the broken line M on the front surface 1A, and the second thermal head 4 comes into contact with the position shown by the broken line N on the back surface 1B. .

  When the printing operation of the paper determination mark is performed in ST3, if the heat-sensitive layer 62 is formed on the surface 1A, a predetermined (square in the figure) paper determination mark 71A is formed on the surface 1A by the first thermal head 2. Are printed in a desired color such as black or red. When the heat sensitive layer 63 is formed on the back surface 1B, the same sheet determination mark 71B is printed by the second thermal head 4 in a desired color such as black or red on the illustrated position of the back surface 1B.

  When the sheet 1 is fed by a predetermined amount h in ST4, the position of the broken line L becomes the position of the cutting line by the cutter mechanism 6. Here, the scanning trajectory of the first mark sensor 7A when being fed by a predetermined amount h is indicated by an arrow 72 in the figure. Further, the scanning locus of the second mark sensor 7B is indicated by an arrow 73 in the figure. The first mark sensor 7A and the second mark sensor 7B are, for example, reflection type optical sensors. When the amount of light reflection is measured along the scanning trajectories 72 and 73 and the colors of the paper determination marks 71A and 71B are detected, A signal with mark detection is output.

  Therefore, when the CPU 11 finishes the predetermined amount h of idle feeding, the detection signals from the sheet determination marks 71A and 71B by the first mark sensor 7A and the second mark sensor 7B are determined as ST5 to ST7. The first mark sensor 7A detects the paper determination mark 71A printed on the front surface 1A of the paper 1 (YES in ST5), and the second mark sensor 7B determines the paper printed on the back surface 1B of the paper 1. If the mark 71B has been detected (YES in ST6), it is determined that the sheet 1 is a double-sided thermal sheet P1 having thermal layers 62 and 63 formed on both sides thereof (sheet determination unit). In this case, the duplex printing mode is set as ST8.

  On the other hand, when the first mark sensor 7A detects the paper determination mark 71A (YES in ST5) but the second mark sensor 7B does not detect the paper determination mark 71B (NO in ST6). The paper 1 is determined to be a single-sided thermal paper P2 in which the heat-sensitive layer 62 is formed only on the front surface 1A (paper determination means). In this case, the front surface printing mode is set as ST9.

  If the first mark sensor 7A does not detect the paper determination mark 71A (NO in ST5), but the second mark sensor 7B detects the paper determination mark 71B (YES in ST7), the paper 1 Is determined to be a single-sided thermal paper P3 having a heat-sensitive layer 63 formed only on the back surface 1B (paper discrimination means). In this case, the back side printing mode is set as ST10.

  If neither the first mark sensor 7A nor the second mark sensor 7B has detected the sheet determination mark 71A and the sheet determination mark 71B (NO in ST5, NO in ST7), the sheet 1 is not a thermal sheet. So it is an error. At this time, a paper error signal may be output to the host device 30 so that the user can be notified that an unusable paper is set. Alternatively, when an operation panel is provided in the printer body, a paper error message may be displayed on the display unit of the panel to notify the user.

  Thus, if any one of the two-sided printing mode, the front-side printing mode, or the back-side printing mode is set, the CPU 11 operates the cutter motor 23 as ST11 to cut the paper 1 at the position of the cutting line L. . As a result, the leading end of the sheet on which at least one of the sheet determination mark 71A and the sheet determination mark 71B is printed is cut off.

  Thereafter, the CPU 11 waits for print data to be sent from the host device as ST12. If the print data is received from the host device 30 and stored in the reception buffer 51, the CPU 11 determines the print mode in ST13. If the double-sided printing mode is set, the CPU 11 sequentially develops the print data into raster data from the top in ST14 and stores it separately in the front image buffer 52 and the back image buffer 53. Then, the raster data stored in the front surface image buffer 52 as ST17 is output line by line to the first thermal head 2 and printed on the front surface 1A of the thermal paper 1, and at the same time, the raster data stored in the back surface image buffer 53 is 1 Line by line is output to the second thermal head 4 and printed on the back surface 1B of the thermal paper 1 (printing control means).

  On the other hand, if the front surface print mode is set, the CPU 11 develops the print data sequentially from the top to raster data in ST15 and stores it in the front surface image buffer 52. In step ST17, the raster data stored in the front surface image buffer 52 is output line by line to the first thermal head 2 and printed only on the front surface 1A of the thermal paper 1 (printing control means).

  If the reverse side printing mode is set, the CPU 11 expands the print data sequentially from the top to raster data and stores it in the reverse side image buffer 53 in ST16. In ST17, the raster data stored in the back image buffer 53 is output line by line to the second thermal head 4 and printed only on the back surface 1B of the thermal paper 1 (printing control means).

  Each time the CPU 11 receives print data from the host device 30, the CPU 11 repeatedly executes the processes of ST13 to ST17. If a reset is performed for paper replacement in ST18, the CPU 11 cancels the print mode and ends this process. The print mode is also canceled when the printer main body is turned off.

  As described above, in the thermal printer 10 of the present embodiment, when the thermal paper 1 is set or when the printer is started, the paper determination marks 71A and 71B are printed on both sides of the paper. Then, it is determined whether or not the sheet determination marks 71A and 71B are printed on each side of the sheet 10.

  Here, if it is determined that the paper determination marks 71A and 71B are printed on the front surface 1A and the back surface 1B, respectively, the thermal paper 1 is a double-sided thermal paper P1 in which the thermal layers 62 and 63 are formed on both the front and back surfaces. Be recognized. Then, the duplex printing mode is set, and thereafter, the printing operation is controlled so that the print data is printed on both sides of the duplex thermal paper P1.

  On the other hand, when it is determined that the paper determination mark 71A is printed only on the front surface 1A, the thermal paper 1 is recognized as the single-sided thermal paper P2 in which the thermal layer 62 is formed only on the front surface 1A. Then, the front surface printing mode is set, and thereafter, the printing operation is controlled so that the print data is printed on the front surface 1A of the single-sided thermal paper P2.

  When it is determined that the paper determination mark 71B is printed only on the back surface 1B, the thermal paper 1 is recognized as the single-sided thermal paper P3 in which the thermal layer 63 is formed only on the back surface 1B. Then, the back side printing mode is set, and thereafter, the printing operation is controlled so that the print data is printed on the back side 1B of the single-sided thermal paper P3.

  Accordingly, double-sided printing is executed only when the double-sided thermal paper P1 is used, and double-sided printing is not executed when the single-sided thermal papers P2 and P3 are used. The problem of not being printed because it was not the paper P1 is eliminated.

  Even if double-sided thermal paper P1 is mistakenly used and single-sided thermal papers P2 and P3 in which a heat-sensitive layer is formed only on the front surface or the back surface are used, the print data is printed on either surface on which the heat-sensitive layer is formed. Since printing is performed, the print data can be reliably printed on the paper.

  FIG. 8 is a diagram schematically illustrating an outline of a printing mechanism unit in the thermal printer 80 according to the second embodiment. This thermal printer 80 is different from the thermal printer 10 of the first embodiment in the number of mark sensors. That is, the thermal printer 80 includes only the second mark sensor 7B that detects a predetermined paper determination mark printed on the back surface 1B of the thermal paper 1, and the predetermined paper determination mark printed on the front surface 1A of the thermal paper 1. The first mark sensor 7A for detecting is omitted.

  As shown in FIG. 5A, the thermal paper 1 usable in the thermal printer 80 is a double-sided thermal paper P1 in which heat-sensitive layers 62 and 63 are formed on the front and back sides of the base paper 61, respectively, as shown in FIG. As shown, there are two types of single-sided thermal paper P2 corresponding to the surface in which the heat sensitive layer 62 is formed only on the surface of the base paper 61.

  The CPU 11 of the thermal printer 80 executes processing of the procedure shown in the flowchart of FIG. 9 in response to a power-on operation or a reset operation after paper replacement. First, in ST21, it is determined whether or not the thermal paper 1 is set normally. If the paper 1 has been set normally, the CPU 11 controls the paper feed motor 22 in ST22 to feed the paper 1 by a predetermined amount f. This feed amount f is an amount substantially equal to the separation distance from the first thermal head 2 to the cutter 6 as in the first embodiment.

  If the paper 1 is fed by a predetermined amount f, the CPU 11 converts the print data of the paper judgment mark into dots in ST23, and develops and stores only in the back image buffer 53. Then, the raster image data of the paper determination mark stored in the back surface image buffer 53 is output to the second head drive circuit 20 and printed on the back surface 1B of the paper 1 by the second thermal head 4 (mark printing means).

  Next, in step ST24, the CPU 11 controls the paper feed motor 22 to further feed the paper 1 by a predetermined amount h. The feed amount h is also slightly longer than the separation distance from the second thermal head 2 to the cutter 6 as in the first embodiment.

  Thereafter, the CPU 11 determines whether or not a sheet determination mark is detected by the second mark sensor 7B in ST25. If a paper determination mark is detected, it is determined that it is a double-sided thermal paper P1 (paper determination means), and a double-sided printing mode is set as ST26. On the other hand, when the sheet determination mark is not detected, it is determined that the sheet is a single-sided thermal sheet (sheet determination unit), and the single-sided printing mode is set as ST27.

  When either the duplex printing mode or the simplex printing mode is set in this way, the CPU 11 operates the cutter motor 23 in ST28, and cuts the sheet 1 along the cutting line as in the first embodiment. Cut at position L.

  Thereafter, the CPU 11 waits for print data to be sent from the host device in ST29. If the print data is received from the host device 30 and stored in the reception buffer 51, the CPU 11 determines the print mode as ST30. If the double-sided printing mode is set, the CPU 11 sequentially develops the print data from the top to the raster data in ST31, and stores it separately in the front image buffer 52 and the back image buffer 53. Then, the raster data stored in the front surface image buffer 52 as ST33 is output line by line to the first thermal head 2 and printed on the front surface 1A of the thermal paper 1, and at the same time, the raster data stored in the back surface image buffer 53 is 1 Line by line is output to the second thermal head 4 and printed on the back surface 1B of the thermal paper 1 (printing control means).

  On the other hand, if the single-sided printing mode is set, the CPU 11 sequentially develops the print data from the top into raster data and stores it in the front image buffer 52 in ST32. Then, the raster data stored in the surface image buffer 52 as ST33 is output line by line to the first thermal head 2 and printed only on the surface 1A of the thermal paper 1 (printing control means).

  Each time the CPU 11 receives print data from the host device 30, it repeatedly executes the processes of ST30 to ST33. If a reset is made for paper replacement in ST34, the CPU 11 cancels the print mode and ends this process. The print mode is also canceled when the printer main body is turned off.

  Also in the second embodiment configured as above, double-sided printing is executed only when the double-sided thermal paper P1 is used, and double-sided printing is not executed when the single-sided thermal paper P2 is used. In spite of the above, the problem that the paper is not printed because the paper is not the double-sided thermal paper P1 is eliminated.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage.

  For example, in the first embodiment, the feed amount f is set to the substantially separated distance between the first thermal head 2 and the cutter mechanism 6 in the process of ST2 in FIG. 7, but the first thermal head 2 and the second thermal head are used. If the sheet determination marks 71A and 71B can be printed on both sides of the sheet 1 at 4, the feed amount f is not particularly limited.

  Further, although the feed amount h is set to be slightly longer than the separation distance between the second thermal head 4 and the cutter mechanism 6 in the process of ST4 in FIG. 7, the paper on which the paper determination marks 71A and 71B are printed is not cut. The feed amount h is not particularly limited as long as it can be used for printing the print data as it is.

  For example, this type of thermal printer is used as a receipt printer such as a POS terminal used in a retail store. A receipt printed and issued by a receipt printer is usually printed with a log mark such as a store name at the top. Therefore, by substituting the logo mark as a paper determination mark, it is not necessary to cut the paper on which the paper determination mark is printed even after the paper type is determined.

  In the first embodiment, the paper determination marks 71A and 71B are printed by the thermal printer 10, but a thermal paper on which the paper determination marks 71A and 71B are printed in advance may be used. In this case, the mounting positions of the first mark sensor 7A and the second mark sensor 7B are not limited to the positions in the above-described embodiment, but are positions where the paper determination marks 71A and 71B preprinted on the paper can be detected. I just need it.

  In the second embodiment, the usable single-sided thermal paper is a single-sided thermal paper P3 corresponding to the back surface in which the heat-sensitive layer 63 is formed only on the back surface of the base paper 61 as shown in FIG. There may be. In this case, only the first mark sensor 7A for detecting a predetermined paper determination mark printed on the surface 1A of the thermal paper 1 is provided. If the single-sided printing mode is set, the CPU 11 develops the print data sequentially from the top to the raster data and stores it in the back-side image buffer 53 as ST32. Then, the raster data stored in the back image buffer 53 as ST33 is output to the second thermal head 3 line by line and printed only on the back surface 1B of the thermal paper 1. By doing so, the same operational effects as those of the second embodiment can be obtained.

  In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, the constituent elements over different embodiments may be combined.

1 is a schematic diagram illustrating an outline of a printing mechanism unit of a thermal printer according to a first embodiment of the present invention. FIG. The block diagram which shows the principal part structure containing the control circuit of the thermal printer. FIG. 3 is a block diagram showing a main configuration of a thermal head provided in the thermal printer. The schematic diagram which shows the main memory areas formed in RAM of the thermal printer. FIG. 3 is a schematic diagram showing a sectional structure of thermal paper used in the thermal printer. The figure for demonstrating the state of the paper in which the paper determination mark was printed by the thermal printer. 3 is a flowchart showing a main part of a control processing procedure executed by the CPU of the thermal printer. The schematic diagram which shows the outline of the printing mechanism part of the thermal printer which is the 2nd Embodiment of this invention. 9 is a flowchart showing a main part of a control processing procedure executed by a CPU of a thermal printer in the second embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Thermal paper, 2 ... 1st thermal head, 3 ... 1st platen roller, 4 ... 2nd thermal head, 5 ... 2nd platen roller, 6 ... Cutter mechanism, 7A ... 1st mark sensor, 7B ... 2nd mark Sensor, 11 ... CPU, 21 ... power supply circuit, 23 ... paper feed motor, 24 ... cutter motor, 51 ... reception buffer, 52 ... front image buffer, 53 ... back image buffer, 71A, 71B ... paper determination mark.

Claims (4)

A paper conveying means for conveying one thermal paper among a double-sided thermal paper having a heat-sensitive layer formed on both sides and a single-sided thermal paper having a heat-sensitive layer formed on one of the surfaces;
A first thermal head disposed so as to be in contact with one surface of the thermal paper conveyed by the paper conveying means and performing printing on the one surface;
A second thermal head arranged so as to be in contact with the other surface of the thermal paper conveyed by the paper conveying means and performing printing on the other surface;
A first image buffer in which print data to be printed on one surface of the thermal paper is developed and stored by the first thermal head;
A second image buffer in which print data to be printed on the other surface of the thermal paper is developed and stored by the second thermal head;
Paper discriminating means for discriminating whether or not the thermal layer is formed on each of the one surface and the other surface of the thermal paper;
On the condition that it is determined that the thermal layer is formed on both the one side and the other side of the thermal paper by the paper discrimination means, the received print data is transferred to the first image buffer and the second image buffer. The image data is developed and stored in both buffers of the image buffer, and the print data stored in the image buffers is output to the corresponding first thermal head and the second thermal head, respectively, and the first thermal head and the Ri by the second thermal head performs printing on both sides of the thermal paper, the condition that the heat-sensitive layer on one of the one surface or the other surface of the thermal paper is judged to have been formed on, and the heat-sensitive layer of the print data received first image buffer and the second image buffer is formed discriminated The image data is developed and stored in one image buffer corresponding to the thermal head arranged so as to be in contact with the printed surface, and the print data stored in this one image buffer is output to the corresponding one thermal head. and print control means for printing on one surface of the heat-sensitive layer is determined to have been formed of by Ri the thermal paper in one of the thermal head,
A thermal printer characterized by comprising: A first mark sensor that detects a paper determination mark printed on the one surface of the thermal paper; and a second mark sensor that detects a paper determination mark printed on the other surface of the thermal paper;
The paper discriminating unit discriminates that the thermal layer is formed on the one surface of the thermal paper when the paper judgment mark is detected by the first mark sensor, and the paper is judged by the second mark sensor. 2. The thermal printer according to claim 1, wherein when a determination mark is detected, it is determined that the thermal layer is formed on the other surface of the thermal paper. A paper conveying means for conveying one thermal paper among a double-sided thermal paper having a heat-sensitive layer formed on both sides and a single-sided thermal paper having a heat-sensitive layer formed on one of the surfaces;
A first thermal head disposed so as to be in contact with one surface of the thermal paper conveyed by the paper conveying means and performing printing on the one surface;
A second thermal head arranged so as to be in contact with the other surface of the thermal paper conveyed by the paper conveying means and performing printing on the other surface;
A first image buffer in which print data to be printed on one surface of the thermal paper is developed and stored by the first thermal head;
A second image buffer in which print data to be printed on the other surface of the thermal paper is developed and stored by the second thermal head;
A mark sensor that is disposed on a side to which a surface on which the heat-sensitive layer is not formed is directed when the one-sided thermal paper is conveyed by the paper conveying unit, and detects a paper determination mark printed on the thermal paper;
A paper discriminating means for discriminating that the thermal paper is the double-sided thermal paper when the mark sensor detects the paper judgment mark, and discriminating that the thermal paper is a single-sided thermal paper if the paper judgment mark is not detected. When,
On the condition that the thermal paper is determined to be double-sided thermal paper by the paper discriminating means, the received print data is developed and stored in both the first image buffer and the second image buffer. and outputs the print data stored respectively in the image buffer to the corresponding first thermal head and the second thermal head, Ri by said first thermal head and the second thermal head on both sides of the thermal paper Thermal printing arranged on the side of the first image buffer and the second image buffer where the mark sensor is not arranged on the condition that printing is performed and it is determined that the paper is single-sided thermal paper. Expand and store in one image buffer corresponding to the head, this one image The print data stored in Ffa and outputs to the thermal head provided on the side where the mark sensor is not disposed, the printing on one side of the mark sensor is not disposed of the thermal paper by the thermal head Printing control means to perform ;
A thermal printer characterized by comprising: The mark sensor is disposed downstream of the first thermal head and the second thermal head in the paper transport direction,
Printing of the paper determination mark on the thermal paper transported by the paper transporting means via the thermal head provided on the side of the first thermal head and the second thermal head where the mark sensor is not disposed. 4. The thermal printer according to claim 3 , further comprising mark printing means for performing the above.

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