JP5609079B2 - Direct thermal printer - Google Patents

Description

  The present invention relates to a direct thermal printer capable of performing a printing process by heating thermal paper with a thermal head.

  2. Description of the Related Art Conventionally, there is known a direct thermal printer capable of printing characters, symbols, color images, or the like on a thermal paper by pressing a thermal head on the thermal paper (paper) previously coated with a dye and heating the thermal head. Since such a direct thermal printer performs printing processing by directly pressing a heated thermal head against thermal paper, the screen printed when dust or dirt adheres to the thermal head. As a result, streaks or the like extending in the paper conveyance direction occur, and the print quality deteriorates.

  The cause of dust adhering to the thermal head is that dust adhered to the surface of the paper before the printing process adheres to the thermal head during the printing process, or the surface layer of the paper melted during the printing process. For example, it adheres to the thermal head. In particular, dust or the like tends to adhere to an area corresponding to one outermost winding (outermost peripheral area) of the paper at the time when the paper is stored in the printer casing, and the user can wear the paper without wearing gloves. When the storage operation is performed, sebum and dirt on the user's fingers are likely to adhere to the paper.

  Therefore, in order to avoid such transfer of dust and sebum from the paper to the thermal head (hereinafter, dust and sebum are collectively referred to as “dust”) or to remove dust from the thermal head, After storing the paper in the housing, the outermost part of the outermost roll of the paper is sent to the paper output side without performing the printing process by a predetermined operation, cut by the cutter provided in the housing, (First prior art), a thermal head cleaning using a special cleaning sheet (second prior art), or a region near the rear end of a long sheet of paper The paper is cut out at the section and discharged out of the housing, and then the discharged paper is reloaded into the housing as a cleaning sheet and conveyed while being pressed against the thermal head. Aspects to scrape the dust adhering to the thermal head has been considered (Patent Document 1: 3 prior art) has been considered.

JP 2005-193466 A

  However, in the first prior art, the outermost one turn of the sheet sent to the paper discharge unit is simply discarded, and the sheet is wasted. In the case of the second prior art, a dedicated cleaning sheet is essential, which is disadvantageous in terms of operation and cost. Further, in the third prior art, since the paper once discharged out of the housing has to be loaded again into the housing as a cleaning sheet, a troublesome operation is forced on the user, which is inconvenient from the viewpoint of practicality. Is.

  The present invention has been made paying attention to such problems, and its main purpose is to use a part of the paper without incurring wasteful use of the paper, cumbersome operation for the user, and compulsory pre-preparation. It is an object of the present invention to provide a direct thermal printer that can be used to clean a thermal head.

That is, the direct thermal printer of the present invention includes a paper storage unit for storing a long paper wound in a roll shape that can be colored by heating a pre-applied dye with a thermal head, and a paper storage unit side. Between the feed head that can feed paper in the feed direction toward the thermal head side and the print direction from the thermal head side to the paper storage side, and the pinch roller that can hold the paper between the feed roller and the thermal head And a platen capable of sandwiching paper.

  The direct thermal printer of the present invention further includes a paper leading edge detection unit that detects the leading edge of the paper along the feeding direction, and at least a predetermined length from the leading edge of the paper detected by the paper leading edge detection unit as a feed roller. The thermal head can be cleaned by passing it between the pinch rollers and feeding it in the feed direction, pressing the thermal head against the paper while carrying the paper in the print direction by a predetermined length, and performing the printing process. It is characterized by having a head cleaning function.

  If this is the case, it is attached to the thermal head by directly contacting the heated thermal head with a predetermined length from the leading edge of the paper where dust is likely to adhere during storage operations or during print processing standby. Dust can be scraped off with a sheet of this predetermined length, and the thermal head can be cleaned. As a result, when a normal print process is performed after this cleaning process, good print quality can be obtained.

  In addition, the direct thermal printer according to the present invention does not require a dedicated cleaning sheet, for example, as compared with an embodiment in which a thermal head is cleaned using another dedicated cleaning sheet, and can reduce costs. In addition, the direct thermal printer according to the present invention has a special operation for cleaning the thermal head as compared with a mode in which the paper once discharged out of the housing is loaded again into the housing and used as cleaning paper ( (Reloading of paper) is not forced, and the operability is excellent.

  Further, in the direct thermal printer according to the present invention, if the area of the sheet to be cleaned is an area corresponding to one outermost winding of the sheets stored in a roll shape in the sheet storage unit, what is the conventional case? The thermal head can be cleaned by effectively using the area corresponding to the outermost winding of the paper that was simply cut and discarded without being used, and the cleaning process does not cause waste of paper. The quality of the normal print processing to be performed later can be improved.

  Further, the direct thermal printer of the present invention may further include a paper trailing edge detection unit that detects the trailing edge of the paper. Then, a thermal head is formed by passing a predetermined length from the rear end of the paper detected by the paper rear end detection unit between the feed roller and the pinch roller in the feeding direction and pressing the thermal head to perform a printing process. If the cleaning process is performed, at least two cleaning opportunities can be obtained with the paper once set in the housing.

  According to the present invention, there is provided a direct thermal printer capable of cleaning a thermal head using a part of paper without incurring waste of paper, complicating operations and compulsory preparation for a user. Can be provided.

1 is an overall configuration schematic diagram of a direct thermal printer according to an embodiment of the present invention. Action | operation explanatory drawing of the direct thermal type printer which concerns on the same embodiment. Action | operation explanatory drawing of the direct thermal type printer which concerns on the same embodiment. Action | operation explanatory drawing of the direct thermal type printer which concerns on the same embodiment. Action | operation explanatory drawing of the direct thermal type printer which concerns on the same embodiment. Action | operation explanatory drawing of the direct thermal type printer which concerns on the same embodiment. Action | operation explanatory drawing of the direct thermal type printer which concerns on the same embodiment. Action | operation explanatory drawing of the direct thermal type printer which concerns on the same embodiment.

  The direct thermal printer X according to an embodiment of the present invention applies a print process to the paper S by directly pressing the thermal head 2 against a long thermal paper (hereinafter referred to as “paper S”) and heating it. It is.

  The paper S used in the present embodiment is obtained by forming a thermosensitive coloring layer on the upper surface of a base layer. The thermosensitive coloring layer may be a plurality of layers in which, for example, a cyan thermosensitive coloring layer, a magenta thermosensitive coloring layer, and a yellow thermosensitive coloring layer are laminated in this order. Has been applied. The heat-sensitive coloring layer is made of a dye that develops color when heated, and is formed by applying such a dye on the upper surface of the base layer. The thermosensitive coloring layer may be covered with a protective layer.

  As shown in FIG. 1, a direct thermal printer X according to the present embodiment that performs print processing on such a sheet S has a sheet roll storage unit 1 that stores a roll-shaped sheet S (“sheet storage” of the present invention). The thermal head 2, the platen roller 3 (corresponding to the “platen” of the present invention) disposed at a position facing the thermal head 2, and the paper feed side (sheet roll storage) than the thermal head 2. A feed roller 4 disposed on the portion 1 side), a main pinch roller 5 (corresponding to the “pinch roller” of the present invention) that can sandwich the paper S between the feed roller 4, and a paper roll rather than the feed roller 4. The paper feed guide roller 6 disposed on the storage unit 1 side, the paper feed guide pinch roller 7 capable of sandwiching the paper S between the paper feed guide roller 6, and the side opposite to the paper roll storage unit 1 than the thermal head 2 ( The feed roller 8 arranged on the paper discharge unit H side described below, the feed pinch roller 9 capable of sandwiching the paper S between the feed roller 8, and the anti-thermal head 2 side of the feed roller 8. A cutter unit C and a paper discharge unit H are provided.

  The paper roll storage unit 1 can accommodate the paper S wound in a roll shape around the roll shaft 1a. In the present embodiment, the paper S is wound in a roll shape so that the thermosensitive coloring layer is relatively outward from the base layer. The roll shaft 1 a can rotate in the forward and reverse directions in synchronization with the feed roller 4.

  The thermal head 2 is a known head that prints on the paper S by generating heat from a plurality of heating elements (not shown) aligned in a predetermined direction that coincides with the width direction of the paper S. In the present embodiment, the thermal head 2 is set so as to be movable between a printable position where the paper S can be sandwiched with the platen roller 3 and a retracted position where the thermal head 2 cannot be sandwiched by a head drive motor (not shown). ing. The operation of the thermal head 2 can be controlled by a print controller (not shown).

  The platen roller 3 can sandwich the paper S with the thermal head 2 and has a function of sequentially transporting the paper S while rotating. The platen roller 3 can rotate in the forward and reverse directions in synchronization with the feed roller 4.

  The feed roller 4 travels from the thermal head 2 side to the paper roll storage unit 1 side in the first transport direction a in which the paper S can be transported in the feed direction A from the paper roll storage unit 1 side to the thermal head 2 side. It can rotate forward and backward in the second transport direction b that can be transported in the print direction B. The “feeding direction A” coincides with the direction from the thermal head 2 side toward the paper discharge unit H, and the “print direction B” coincides with the direction from the paper discharge unit H side toward the thermal head 2 side.

  The main pinch roller 5 rotates in the forward and reverse directions following the rotation of the feed roller 4 while in direct contact with the feed roller 4 or indirectly through the paper S.

  The paper feed guide roller 6 can rotate forward and backward in a first transport direction c in which the paper S can be transported in the delivery direction A and in a second transport direction d in which the paper S can be transported in the print direction B. The paper feed guide pinch roller 7 rotates in the forward and reverse directions following the rotation of the paper feed guide roller 6 in a state where it is in direct contact with the paper feed guide roller 6 or indirectly through the paper S. .

  The feed roller 8 can rotate forward and backward in a first transport direction e in which the paper S can be transported in the feed direction A and in a second transport direction f in which the paper S can be transported in the print direction B. The feed pinch roller 9 is rotated by the rotation of the feed roller 8 in a state where the feed pinch roller 9 is in direct contact with the feed roller 8 or indirectly through the paper S.

  The cutter unit C cuts the paper S for each predetermined size, and cuts the paper S set with a plurality of print screens at least at the boundaries of the print screens. In the present embodiment, the cutter unit C is configured by using a pair of cutter bodies that are disposed so as to sandwich the paper S therebetween.

  The paper discharge unit H includes a paper discharge port H1, a paper discharge roller H2 that sends the paper S to the paper discharge port H1, a paper discharge pinch roller H3 that can hold the paper S between the paper discharge rollers H2, and a paper discharge A paper discharge tray H4 that receives the paper S discharged from the opening H1 is provided. The paper discharge roller H2 can rotate forward and backward in a first transport direction g in which the paper S can be transported in the delivery direction A and in a second transport direction h in which the paper S can be transported in the print direction B. Further, the paper discharge pinch roller H3562 is rotated by the rotation of the paper discharge roller H2 in a state where it is in direct contact with the paper discharge roller H2 or indirectly through the paper S.

  In the present embodiment, the thermal head 2, the main pinch roller 5, the paper feed guide pinch roller 7, the feed pinch roller 9, and the paper discharge pinch roller H3 are arranged on the front surface Sa side (thermosensitive coloring layer side) of the paper S. The platen roller 3, the feed roller 4, the paper feed guide roller 6, the feed roller 8, and the paper discharge roller H2 are arranged on the back side (base layer side) of the paper S.

  Further, the direct thermal printer X according to the present embodiment has a paper leading edge detection unit Y that detects the leading edge S1 of the paper S along the feeding direction A, and a trailing edge of the paper S along the feeding direction A (not shown). And a paper trailing edge detection unit Z for detecting the above.

  The paper leading edge detection unit Y is disposed between the platen roller 3 and the feed roller 4, and the paper trailing edge detection unit Z is disposed between the feed roller 4 and the paper feed guide roller 6. It is. In the present embodiment, the sheet leading edge detection unit Y and the sheet trailing edge detection unit Z are configured by sensors.

  In the direct thermal printer X of the present embodiment, members other than the discharge tray H4 of the discharge portion H among these members are provided in a common housing K.

  Direct thermal printers have increased in the number of print processes, etc., and dust and debris adhering to the surface of the paper or sebum (oil) in the user's hand (hereinafter collectively referred to as “dust”). May adhere to the surface or part of the thermal head that can come into contact with the paper, which may lead to degradation of print quality. Therefore, the direct thermal printer X according to the present embodiment is configured to have a head cleaning function for cleaning the thermal head 2 using the above-described members and parts.

  Next, the usage method, operation, and action of the direct thermal printer X according to this embodiment, particularly the head cleaning function, will be described with reference to FIGS. 2 to 8 schematically show the paper S viewed from the upper side Sa (the heat-sensitive coloring layer side) from the upper side in the lower area of each paper surface in order to show the relative positional relationship between the printer X and the paper S. Represents.

  First, the user stores the roll-shaped paper S in the paper roll storage unit 1 manually. After storing the paper S in the paper roll storage unit 1, the user transports the paper S in the delivery direction A to the position where the leading edge S 1 of the paper S reaches the paper leading edge detection unit Y manually or using an appropriate tool. (See FIG. 2). At this time, the main pinch roller 5 is in a retracted position where the paper S cannot be sandwiched between the main pinch roller 5 and the feed roller 4. Accordingly, the user can sandwich the paper S between the paper feed guide roller 6 and the paper feed guide pinch roller 7 while a gap larger than the thickness of the paper S is formed between the feed roller 4 and the main pinch roller 5. The sheet S can be smoothly sent out in the feeding direction A to the position where the sheet leading edge S1 reaches the sheet leading edge detection unit Y.

  In the direct thermal printer X of the present embodiment, when the paper front end S1 reaches the paper front end detection unit Y, the paper front end detection unit Y detects the paper front end S1 and is transmitted from the paper front end detection unit Y. On the basis of the detection signal, the main pinch roller 5 moves from the retracted position to the nipping position where the sheet S is nipped between the feed roller 4 and the feed roller 4 is rotationally driven in the first transport direction a, thereby the sheet S Is conveyed in the delivery direction A (see FIG. 3). At this time, the platen roller 3 rotates in the same direction as the feed roller 4, and the paper feed guide roller 6, the feed roller 8 and the paper discharge roller H 2 are also synchronized with the feed roller 4 in the first transport direction (first transport direction). c, the first transport direction e, and the first transport direction g). A synchronization mechanism that synchronizes these rollers can be configured using a timing pulley (not shown) or the like.

  The direct thermal printer X of the present embodiment has a predetermined length from the sheet leading edge S1, specifically, a length corresponding to one turn of the outermost circumference of the sheet S when stored in the sheet roll storage unit 1 ( Hereinafter, an area corresponding to one turn of the outermost periphery of the paper S is referred to as “outermost peripheral area S3”) is passed between the thermal head 2 and the platen roller 3, and the rear end of the paper S in the outermost peripheral area S3. When the end on the end side (hereinafter referred to as “the outermost peripheral end S31”) reaches the pressure contact portion between the thermal head 2 and the platen roller 3, or the outermost end S31 exceeds the pressure contact portion and reaches the paper discharge section H side. At that time, the rotation of each roller (feed roller 4, platen roller 3, paper feed guide roller 6, feed roller 8, paper discharge roller H2) is stopped (see FIG. 4). As a method of detecting the position of the outermost peripheral end S31, for example, a method of detecting and calculating the rotation angle of the motor that drives the feed roller 4 or the number of steps of the stepping motor can be employed. Each pinch roller (main pinch roller 5, paper feed guide pinch roller 7, feed pinch roller 9, paper discharge pinch roller H3) is opposed to each other (feed roller 4, paper feed guide roller) as described above. 6, the feed roller 8, the paper discharge roller H <b> 2, and the respective pinch rollers (main pinch roller 5) when each roller (feed roller 4, paper feed guide roller 6, feed roller 8, paper discharge roller H <b> 2) stops. The paper feed guide pinch roller 7, the feed pinch roller 9, and the paper discharge pinch roller H3) are also stopped. In the following description, the operation of each pinch roller (main pinch roller 5, paper feed guide pinch roller 7, feed pinch roller 9, paper discharge pinch roller H3) will not be described in detail.

  Next, in the direct thermal printer X of the present embodiment, the printable position where the thermal head 2 can sandwich the paper S with the platen roller 3 from the retracted position where the paper S cannot be sandwiched with the platen roller 3. And a predetermined energy is applied to all the power generation elements (energized state). Then, as shown in FIG. 5, by pressing the energized thermal head 2 against the paper surface Sa, the dye (thermosensitive coloring layer) applied to the paper S is colored by receiving heat from the thermal head 2. At this time, in the direct thermal printer X of the present embodiment, the heat generation temperature of the heating element is the highest or substantially the highest in print density (color density of the dye forming the heat sensitive color developing layer) in relation to the thermal head 2 and the paper S. The temperature is set to As a result of a test conducted by the present inventors, it was confirmed that a high cleaning effect can be obtained when the temperature of the thermal head 2 (the heat generation temperature of the heat generating element) is set to a temperature at which the printing density becomes the highest.

  The feed roller 4 is driven to rotate in the second transport direction b at the same time when the energized thermal head 2 is pressed against the paper S or slightly behind the timing, so that the paper S is transported in the print direction B. (See FIG. 5). At this time, the platen roller 3 rotates in the same direction as the feed roller 4, and the paper discharge roller H 2, the feed roller 8, and the paper feed guide roller 6 are also synchronized with the feed roller 4 in the second transport direction (second transport direction h). , Rotate in the second transport direction f, the second transport direction d). As a result, the direct thermal printer X of the present embodiment performs a printing process by pressing the energized thermal head 2 against the surface Sa of the sheet S while conveying the sheet S in the printing direction B. In this embodiment, since energy is applied to all the heating elements, the thermal head 2 is placed on the surface Sa of the paper S that passes between the thermal head 2 and the platen roller 3 and is conveyed in the printing direction B. A belt-like high-density print process corresponding to the width dimension (print process painted black) is performed (see FIG. 5). The direct thermal printer X according to the present embodiment directly contacts the paper S with the thermal head 2 set to a temperature at which the print density is highest, so that the surface of the thermal head 2 that can contact the paper S Dust adhering to the portion can be scraped off with the paper S. That is, in the present embodiment, this high-density printing process is a cleaning process in which dust adhering to the thermal head 2 is scraped with the paper S.

  At the timing when the leading edge S1 of the sheet S passes through the pressure contact portion between the thermal head 2 and the platen roller 3, or at a timing slightly earlier than the timing, the direct thermal printer X according to the present embodiment has each roller (feed roller 4, The rotation of the platen roller 3, the paper feed guide roller 6, the feed roller 8, and the paper discharge roller H2) is stopped and the energized state of the thermal head 2 is released. At this time, a belt-like image (a black image in the present embodiment) is printed on the outermost peripheral area S3 of the paper S (see FIG. 6), and the cleaning process of the thermal head 2 is completed.

  Subsequently, the thermal head 2 is moved from the printable position to the retracted position, and the feed roller 4 is rotationally driven in the first transport direction a to transport the paper S in the feed-out direction A (see FIG. 7). At this time, the platen roller 3 rotates in the same direction as the feed roller 4, and the paper discharge roller H 2, the feed roller 8, and the paper feed guide roller 6 are also synchronized with the feed roller 4 in the first transport direction (first transport direction g). , Rotate in the first transport direction e, the first transport direction c).

  Each roller (feed roller 4, platen roller 3, paper feed guide roller 6, feed roller 8, paper discharge, at the timing when the outermost peripheral end S31 of the paper S reaches the cutter part C or at a timing slightly behind the timing. The rotation of the roller H2) is stopped, and the cutter portion C cuts the outermost peripheral end S31 of the paper S or the portion slightly closer to the rear end of the paper than the outermost peripheral end S31. The paper is discharged from the paper discharge outlet H1 to the paper discharge tray H4 while being sandwiched between the paper discharge roller H2 rotated in the rotation direction g and the paper discharge pinch roller H3 (see FIG. 8). The main pinch roller 5 is separated from the feed roller 4 until the sheet S subjected to the cleaning process (the sheet S printed in the outermost peripheral area S3) is conveyed in the feeding direction A and discharged to the sheet discharge tray H4. The sheet S may be retracted to a retracted position where the sheet S cannot be sandwiched between the feed roller 4 and the sheet.

  The outermost peripheral area S3 of the paper S can be discharged out of the housing K by the above procedure. The direct thermal printer X of the present embodiment performs normal print processing after completing such loading operation (preparation operation for enabling normal print processing by the thermal head 2). Can do. Here, “normal print processing (normal print processing)” is an expression used for convenience to distinguish from the print processing (cleaning print processing) performed during the above-described cleaning processing, and a desired image, character, It includes all processes for printing symbols and the like on paper.

  In this normal print processing, the paper S is conveyed by the length corresponding to the number of print screens on which the print processing is performed to the paper discharge portion H side from the press contact portion between the thermal head 2 and the platen roller 3, and then the paper S is printed. The thermal head 2 is pressed against the surface Sa of the paper S while being conveyed in the direction B. The printer X of the present embodiment transports the sheet S that has been subjected to the normal printing process in the feeding direction A, cuts it by a cutter unit C in a predetermined size or in units of print screens, and then discharges it from the discharge port H1 to the discharge tray H4. It is configured to discharge.

  As described above, the direct thermal printer X according to the present embodiment has an area corresponding to one turn of the outermost circumference of the paper S that has been conventionally cut and discarded without any use (the outermost circumference area). Since the configuration is such that the thermal head 2 can be cleaned using S3), the waste of the paper S is not incurred, and the quality of the normal print processing performed after the cleaning processing can be improved. In addition, the direct thermal printer X of the present embodiment does not require a dedicated cleaning sheet and can reduce costs compared to a mode in which the thermal head 2 is cleaned using, for example, another dedicated cleaning sheet. it can.

  In the direct thermal printer X according to the present embodiment, a loading operation (operation for enabling normal print processing) that is automatically performed following the work of storing the paper S in the paper roll storage unit 1 by the user. ), The thermal head 2 is cleaned. For example, the paper S once discharged out of the housing K from the paper discharge tray H4 is loaded again into the housing K and used as a cleaning paper. Compared to the mode of use, the user is not forced to perform the troublesome work of reloading the paper S for cleaning, and the user does not need to be aware of the timing of cleaning regularly (new to the printer X). The thermal head 2 can be cleaned every time the roll paper S is set.

  The direct thermal printer X according to the present embodiment has a direction in which the paper S is conveyed from the paper feed side (paper roll storage unit 1 side) toward the paper discharge unit H (feeding direction A) and the paper S during the printing process. When the sheet S is conveyed in the printing direction B, the conveyance direction (printing direction B) is opposite to the feed roller 4 disposed on the sheet feeding side (sheet roll storage unit 1 side) with respect to the thermal head 2. The sheet S is sandwiched between the main pinch roller 5. Therefore, the area between the trailing edge of the sheet and the last print screen among the print screens set on the sheet S becomes a print non-use area where it is impossible or difficult to perform the normal print process.

  Therefore, the direct thermal printer X of the present embodiment is configured so that the thermal head 2 can be cleaned using this non-printing area. In the direct thermal printer X, as described above, the paper trailing edge detection unit Z is disposed between the paper feed guide roller 6 and the feed roller 4. In the direct thermal printer X of the present embodiment, when the trailing edge of the sheet is detected by the sheet trailing edge detection unit Z, the thermal head 2 is moved from the retracted position to the printable position, and all the power generation elements are set to a predetermined value. Energy is applied (energized state). Simultaneously or substantially simultaneously with this, the paper S is conveyed in the printing direction B and the energized thermal head 2 is pressed against the non-printable area of the paper S, so that it is applied to the non-printable area of the paper S. The dye (heat-sensitive coloring layer) is colored by the heat of the thermal head 2. At this time, in the direct thermal printer X of the present embodiment, the heat generation temperature of the heat generating element is set to a temperature at which the print density is highest or substantially highest in the relationship between the thermal head 2 and the paper S.

  In this way, the direct thermal printer X of the present embodiment presses the energized thermal head 2 against the unprintable area of the paper S while conveying the paper S in the printing direction B, and print density. By directly contacting the thermal head 2 set to a temperature at which the temperature becomes highest with the paper S, dust adhering to the surface or part of the thermal head 2 that can come into contact with the paper S can be scraped off with the paper S. In this embodiment, since energy is applied to all the heating elements, the unprintable area of the paper S that passes between the thermal head 2 and the platen roller 3 corresponds to the width dimension of the thermal head 2. A belt-like high density printing process is performed. The paper S on which the high density printing process has been performed passes between the paper feed guide roller 6 and the paper feed guide pinch roller 7 and is stored in the paper storage unit 1.

  As described above, the direct thermal printer X according to the present embodiment, in addition to the cleaning process linked to the loading operation described above, between the trailing edge and the last print screen of the paper S wound in a roll shape. Since the thermal head 2 can be cleaned by using the non-printable area formed on the paper S, at least two cleaning opportunities can be obtained with the paper S once set in the housing K. In addition, any of the cleaning processes does not require a specific work from the user, and is advantageous in terms of handling.

  Note that the direct thermal printer X according to the present embodiment transports the paper S in the feed direction A and the print direction B along the transport path without performing print processing (including cleaning print processing) by the thermal head 2. In this case, the thermal head 2 is kept in a retracted position where the sheet S cannot be sandwiched between the thermal head 2 and the platen roller 3, thereby realizing the smooth conveyance of the sheet S.

  The present invention is not limited to the embodiment described above. For example, in the above-described embodiment, the print process for cleaning is performed while conveying the area of the paper that is used for the cleaning process in one direction (the printing direction if the outermost peripheral area, the sending direction if the non-printable area). Although the mode of performing is illustrated, the print process for cleaning may be performed while reciprocating the area of the paper to be subjected to the cleaning process one or more times in the printing direction and the feeding direction.

  In the direct thermal printer according to the present invention, the head cleaning process can also be performed using only one of the front end side and the rear end side of the paper. For example, when gloves are worn and the paper is set in the housing with careful handling so that the hand does not touch the paper directly, or dust attached to the outermost peripheral area of the paper before setting in the housing is treated appropriately. In the case of removing by the above, it is possible to perform the normal print processing without performing the head cleaning processing on the area on the front end side of the paper. Also, it is left to the user's operation to select whether the head cleaning process is not performed at all in the rear end area of the paper or only when the length of the paper in the rear end area used for cleaning is sufficient. May be. Alternatively, if the print quality deteriorates due to dust adhering to the thermal head in the middle of the paper, a cleaning process may be performed at that time. That is, in the direct thermal printer of the present invention, it is possible to perform the cleaning process using an area (arbitrary area) other than the outermost peripheral area and the non-printable area of the paper.

  In addition, as a paper trailing edge detection unit, a mode in which the trailing edge of the paper is detected based on a change in the diameter (roll diameter) of the paper wound in a roll shape in the paper storage unit, or the rotation speed of the roll shaft of the paper storage unit A mode in which the trailing edge of the paper is detected based on the change in the number may be employed.

  In addition, the direct thermal printer of the present invention can also cope with thermal paper coated with a plurality of dyes in advance (thermal paper having a plurality of thermal coloring layers different in color). In this case, a high-quality color image can be obtained. It is possible to print.

  In addition, the energy applied to the heating element during the cleaning process and the print pattern (whether it is painted or shaded) are appropriately changed according to the type of paper, etc., and the print density in the relationship between the thermal head and the paper Is preferably as high as possible. Therefore, depending on the type of paper, the print process for the cleaning process may not be the high density print process.

  A plate-shaped plastic template can also be applied as the platen.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

1. Paper storage unit (paper roll storage unit)
2 ... Thermal head 3 ... Platen (Platen roller)
4 ... feed roller 5 ... pinch roller (main pinch roller)
S ... paper X ... direct thermal printer Y ... paper leading edge detector Z ... paper trailing edge detector

Claims (3)

A paper storage unit for storing a long paper wound in a roll shape that can be colored by heating a pre-applied dye with a thermal head;
A feed roller capable of transporting the paper in a feeding direction from the paper storage unit side toward the thermal head side and a printing direction from the thermal head side toward the paper storage unit side;
A pinch roller capable of sandwiching the paper between the feed roller;
A platen capable of sandwiching the paper between the thermal head;
It and a sheet leading edge detection unit for detecting the leading edge of the sheet along the feeding direction,
At least a predetermined length from the front end of the paper detected by the paper front end detection unit is passed between the feed roller and the pinch roller and sent in the feed direction, and the paper is fed by the predetermined length. A direct thermal printer characterized in that a thermal head cleaning process can be performed by pressing the thermal head against the paper while carrying it in the printing direction to perform a printing process. 2. The direct thermal printer according to claim 1, wherein the predetermined length from the leading edge of the paper is a length corresponding to one turn of the outermost circumference of the paper stored in a roll shape in the paper storage unit. A paper trailing edge detection unit for detecting the trailing edge of the paper;
A predetermined length from the trailing edge of the sheet detected by the sheet trailing edge detection section is passed between the feed roller and the pinch roller to be fed in the feeding direction, and pressed by the thermal head to perform a printing process. 3. The direct thermal printer according to claim 1, wherein the thermal head cleaning process can be performed.

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