JP2010006076A - Ink ribbon cassette and printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink ribbon cassette which can determine a remaining amount of an ink ribbon even without forming a flange to a ribbon core, and which never be a cause of even defects of an ink ribbon unit and failures of a printer body. <P>SOLUTION: A magnetic line of force 51 is generated which runs from a fixed part (part of 52) of an inner peripheral surface 50a of the cylindrical ribbon core 50 for delivery to an opposite part (part of 54) of the opposite side to the fixed part. A first magnet 52 is fixed to the fixed part, and a second magnet 54 is arranged on the part of the opposite side. While the ink ribbon cassette 40 is attached to the body of a printer 10, a magnetic sensor 24 is located at a center part inside the ribbon core 50 for delivery, and therefore, this magnetic sensor 24 detects the magnetic line of force 51. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ink ribbon cassette including a cylindrical ribbon core formed with an outer peripheral surface around which an ink ribbon is wound, and a printer to which the ink ribbon cassette is mounted.

  2. Description of the Related Art A thermal transfer type printer that forms (prints) an image on a recording medium by bringing a thermal head (printing head) into pressure contact with an outer peripheral surface of a platen roller via a recording medium (paper) and an ink ribbon is known. In this thermal transfer type printer, an ink ribbon cassette having a cylindrical ribbon core formed with an outer peripheral surface around which an ink ribbon having a predetermined width is wound is detachably mounted. The ribbon core includes a sending ribbon core in which an unused ink ribbon is wound and sent out, and a winding ribbon core that is sent out from the sending ribbon core and wound up with a used ink ribbon.

  When an image is formed by the printer, the ink ribbon is sent out from the sending ribbon core at a constant transport speed by rotating the platen roller at a constant rotational speed. When the ink ribbon is sufficiently left (wound) on the sending ribbon core, the outer diameter of the sending ribbon core is large, so the rotation speed of the sending ribbon core is slow. However, as the ink ribbon is delivered from the delivery ribbon core, the outer diameter of the delivery ribbon core decreases, and the rotation speed gradually increases. On the other hand, the winding ribbon core, contrary to the sending ribbon core, increases in outer diameter of the winding ribbon core as the ink ribbon is sent out from the sending ribbon core, so its rotational speed is gradually slowed down. Become.

  Since the outer diameter can be detected by measuring the rotational speed of the sending ribbon core (or the winding ribbon core) as described above, the remaining amount of the ink ribbon can be determined. As a technique for measuring the rotational speed, a magnetic member is provided by forming a flange at one longitudinal end of a cylindrical ribbon core, and the magnetic force generated from the magnetic member is detected by a magnetic sensor to determine the rotational speed. A technique for measuring is known (for example, see Patent Document 1).

JP 2003-211801 A

  However, as described above, in the technology in which a flange is formed on the ribbon core and a magnetic member is provided, and the magnetic force generated by the magnetic member is detected by the magnetic sensor to measure the rotation speed, the gap between the magnetic sensor and the flange is measured. In some cases, there are parts and members constituting the ink ribbon unit. In this case, it is necessary to increase the magnetic force of the magnetic member. When the magnetic force of the magnetic member is increased, a clip or a staple needle or the like may adhere to the flange due to this magnetic force.

  In such a case, if the ink ribbon unit is installed in the printer body without noticing the clip attached to the ribbon core flange, the ink ribbon unit may malfunction or the clip may fall into the printer body and fail. It may cause

  Further, in the operation of winding the ink ribbon around the outer peripheral surface of the cylindrical ribbon core, the flange of the ribbon core becomes an obstacle to the operation. In addition, since the ink ribbon having a width corresponding to the plate thickness of the flange is cut and wound around the ribbon core, a waste portion of the ink ribbon is generated and the cost is increased.

  In view of the above circumstances, the present invention is capable of determining the remaining amount of ink ribbon without forming a flange on the ribbon core, and that does not cause a malfunction of the ink ribbon unit or a printer main body, and an ink ribbon An object of the present invention is to provide a printer that can quickly determine whether a ribbon is clogged.

In order to achieve the above object, an ink ribbon cassette of the present invention comprises an ink ribbon for forming an image on a recording medium and a cylindrical ribbon core around which the ink ribbon is wound.
(1) It is provided with the 1st magnet and the 2nd magnet which are arranged in the inner peripheral surface of the ribbon core, and are arranged in the position which the central part of the height direction of the ribbon core opposes. To do.

here,
(2) The ribbon core is composed of a cylindrical outer core around which an ink ribbon is wound, and a cylindrical inner core mounted inside the outer core,
(3) The first and second magnets may be attached to the outer peripheral surface of the inner core.

Also,
(4) The first magnet is attached to a certain portion of the outer peripheral surface of the inner core,
(5) The second magnet may be attached to a portion of the outer peripheral surface of the inner core that faces the fixed portion.

In order to achieve the above object, a printer of the present invention is a printer that forms an image on a recording medium by pressing a thermal head on the outer peripheral surface of a platen roller via a recording medium and an ink ribbon.
(6) an ink ribbon for forming an image on a recording medium;
(7) a ribbon core composed of a cylindrical outer core around which the ink ribbon is wound, and a cylindrical inner core mounted on the inner side of the outer core;
(8) a rotating shaft for rotating the ribbon core;
(9) a first magnet and a second magnet for generating lines of magnetic force in a space surrounded by the inner peripheral surface of the ribbon core;
(10) A magnetic sensor that is disposed inside the inner peripheral surface of the inner core and detects the lines of magnetic force only when the lines of magnetic force generated by the first and second magnets are in a predetermined direction due to the rotation of the ribbon core. And
(11) The first and second magnets are attached to a central portion in the height direction of the cylindrical ribbon core.

here,
(12) The ribbon core is composed of a cylindrical outer core around which an ink ribbon is wound, and a cylindrical inner core mounted inside the outer core.
(13) The first and second magnets may be attached to the outer peripheral surface of the inner core.

Also,
(14) The first magnet is attached to a fixed portion of the outer peripheral surface of the inner core,
(15) The second magnet may be attached to a portion of the outer peripheral surface of the inner core that faces the fixed portion.

  According to the present invention, the magnetic lines of force continue to be generated from a certain part of the inner peripheral surface of the ribbon core toward the opposite part, and the magnetic lines of force are detected only when the direction of the generated magnetic lines coincides with a predetermined direction. Ink ribbon clogging is determined based on the time from detection to detection next, so that ink ribbon clogging can be quickly determined. Further, since the recording medium is also jammed due to clogging of the ink ribbon, it is possible to quickly determine whether the recording medium is jammed.

1 is a schematic diagram illustrating a schematic configuration of a printer in which an example of an ink ribbon unit of the present invention is incorporated. FIG. 2 is a partial cross-sectional view illustrating a ribbon core for delivery of the ink ribbon unit of FIG. 1. It is a cross-sectional view showing a positional relationship between a ribbon core to which two magnets are fixed and a magnetic sensor, (a) shows a state in which the direction of magnetic lines of force coincides with a predetermined direction (detection direction), and (b) It shows a state in which the direction of the magnetic lines of force is different from the predetermined direction. It is a cross-sectional view showing a ribbon core of a comparative example in which four magnets are fixed. It is a perspective view which shows the manufacturing method of a ribbon core. It is a schematic diagram which shows the method of identifying the magnet of a ribbon core. 5 schematically shows a method of winding an ink ribbon around a ribbon core having the configuration shown in FIG. 5, wherein (a) is a front view and (b) is a side view. FIG. The method of winding an ink ribbon around the ribbon core of the ink ribbon unit of the comparative example is schematically shown, (a) is a front view, and (b) is a side view. It is a block diagram showing a jam judging unit for judging clogging of an ink ribbon. It is a flowchart which shows an example of the procedure for determining clogging of an ink ribbon.

  The present invention has been realized in a thermal transfer type printer that forms an image on a recording medium by pressing a thermal head against the outer peripheral surface of the platen roller via a recording medium and an ink ribbon.

  With reference to FIG. 1, a printer incorporating the ink ribbon unit of the present invention will be described.

  FIG. 1 is a schematic diagram showing a schematic configuration of a printer in which an example of the ink ribbon unit of the present invention is incorporated.

  The printer 10 forms an image on the printing medium by bringing the thermal head 14 into pressure contact with the recording medium (printing medium such as a tube or tape) and the ink ribbon 42 on the outer peripheral surface of the platen roller 12 rotating in the direction of arrow A (see FIG. (Printing) thermal transfer system. An ink ribbon cassette 40 having cylindrical ribbon cores 50 and 60 around which an ink ribbon 42 having a predetermined width (a length in a direction perpendicular to the paper surface in FIG. 1) is wound is attached to and detached from the thermal transfer printer 10. Can be installed freely. The ribbon cores 50 and 60 include a delivery ribbon core 50 in which an unused ink ribbon is wound and delivered, and a take-up ribbon core 60 in which a used ink ribbon is delivered from the delivery ribbon core 50 and taken up. . When the printer 10 forms an image on a printing medium, the printing medium sandwiched between the platen roller 12 and the driven roller 13 is conveyed at a certain conveying speed by rotating the platen roller 12 at a certain rotation speed. At the same time, the ink ribbon 42 is delivered from the delivery ribbon core 50 at a constant transport speed.

  The print medium is inserted from the direction of arrow B and discharged in the direction of arrow C. The print medium inserted from the direction of arrow B is sandwiched between the transport roller 16 and the driven roller 18 and transported. The driven roller 18 is configured to move in conjunction with opening and closing of a cover (not shown). By opening this cover, the driven roller 18 moves away from the position indicated by the two-dot chain line from the position indicated by the solid line and moves away from the conveying roller 16, so that it is easy to insert the print medium. By closing the cover, the driven roller 18 moves to a position where the conveying roller 16 is pressed, and the two rollers 16 and 18 sandwich the print medium and reliably convey it. The print medium on which the image is formed is cut by an appropriate length by the cutter 20 and the cutter receiving surface 22 and discharged in the direction of arrow C. Examples of the print medium include a label tape, a flat tube, a 4 mm ID (index), and the like, which are wound around and stored in a dedicated cassette (not shown).

  A magnetic sensor 24 for detecting magnetic lines of force is fixed to the main body of the printer 10, and this magnetic sensor 24 detects magnetic lines of force only when the direction of the magnetic lines of force matches a predetermined direction. When the ink ribbon cassette 40 is attached to the main body of the printer 10, the magnetic sensor 24 is positioned at the center surrounded by the inner peripheral surface of the cylindrical ribbon core 50 for delivery. Here, the above-described ink ribbon cassette 40 and the magnetic sensor 24 constitute an ink ribbon unit according to the present invention. By attaching the ink ribbon cassette 40 to the main body of the printer 10, a rotation shaft (not shown) is fitted into the inside of the sending ribbon core 50 and the winding ribbon core 60 (the space surrounded by the inner peripheral surface). As a result, the feeding ribbon core 50 and the winding ribbon core 60 rotate at a predetermined rotational speed. In addition, since the magnetic sensor 24 is fixed to a shaft different from the above-described rotation shaft, the magnetic sensor 24 remains fixed to the main body of the printer 10 without rotating.

  With reference to FIG. 2, the delivery ribbon core 50 of the ink ribbon cassette 40 of FIG. 1 will be described.

  FIG. 2 is a partial cross-sectional view showing a delivery ribbon core of the ink ribbon unit of FIG. 2, the same components as those shown in FIG. 1 are denoted by the same reference numerals.

  The feeding ribbon core 50 has a cylindrical shape as described above, and a line of magnetic force 51 from a certain portion (52 portion) of the inner peripheral surface 50a toward the opposite portion (54 portion) opposite to this certain portion. It has occurred. A first magnet 52 is fixed to the fixed portion, and a second magnet 54 is arranged on the opposite portion. The first magnet 52 is fixed so that the N pole is positioned on the inner peripheral surface 50a side and the S pole is positioned on the outer peripheral surface 50b side, and the second magnet 54 is positioned on the inner peripheral surface 50a side. The S pole is positioned and fixed so that the N pole is positioned on the outer peripheral surface 50b side. As a result, a magnetic force line 51 from the N pole of the first magnet 52 to the S pole of the second magnet 54 is generated inside the sending ribbon core 50 (a space surrounded by the inner peripheral surface 50a).

  When the ink ribbon cassette 40 is removed from the main body of the printer 10, the first magnet 52 and the second magnet 54 are located away from the casing of the ink ribbon cassette 40. It does not adhere to the ink ribbon cassette 40 by magnetic force.

  In the state where the ink ribbon cassette 40 is mounted on the main body of the printer 10, the magnetic sensor 24 is located at the center of the inside of the sending ribbon core 50, so that the magnetic sensor 24 detects the magnetic force line 51. This detection will be described with reference to FIGS.

  With reference to FIG. 3 and FIG. 4, the magnetic force lines and detection thereof in the ribbon core of FIG. 2 will be described.

  FIG. 3 is a cross-sectional view showing the positional relationship between a ribbon core to which two magnets are fixed and a magnetic sensor. FIG. 3A shows a state in which the direction of magnetic lines of force coincides with a predetermined direction (detection direction). b) shows a state in which the direction of the lines of magnetic force is different from the predetermined direction. FIG. 4 is a cross-sectional view showing a ribbon core of a comparative example in which four magnets are fixed.

  The magnetic sensor 24 incorporates a detection element 24a that detects lines of magnetic force. The detection element 24a can detect the magnetic lines of force to distinguish the positions of the N pole and the S pole (the direction of the magnetic lines of force can be distinguished) and the magnetic pole can be detected, but the positions of the N pole and the S pole cannot be distinguished. There are two types of unipolar detection type. Regardless of the type of the detection element 24a, as shown in FIG. 3A, the magnetic field lines 51 are detected by the detection element 24a only when the direction of the magnetic field lines 51 coincides with a predetermined direction (detection direction). Is done. The detection direction here refers to the direction of the lines of magnetic force 51 shown in FIG. 3A and the opposite direction. As shown in FIG. 3B, when the direction of the magnetic force lines 51 does not coincide with the predetermined direction (detection direction) (different), the magnetic force lines 51 are not detected by the detection element 24a.

  Therefore, when the detection element 24a is a bipolar detection type, when the sending ribbon core 50 makes one rotation in the circumferential direction (arrow D direction), the magnetic field lines 51 having opposite directions can be detected once (that is, twice in total). It becomes. In other words, when the sending ribbon core 50 is rotated halfway in the circumferential direction (arrow D direction), the lines of magnetic force can be detected once while distinguishing the direction. On the other hand, when the detection element 24a is a single pole detection type, when the sending ribbon core 50 is rotated halfway in the circumferential direction (arrow D direction), the magnetic force lines 51 can be detected once without distinguishing the direction. In the above-described example, the magnetic force lines are generated inside the feeding ribbon core 50. However, the magnetic force lines may be generated inside the winding ribbon core 60.

  By the way, in the sending ribbon core 50, two magnets 52 and 54 are arranged at positions facing each other to generate magnetic lines of force inside the sending ribbon core 50. Three or more magnets may be arranged in order to generate magnetic lines of force inside. For example, as shown in FIG. 4, a delivery ribbon core 150 in which four magnets 151, 152, 153, and 154 are fixed at equal intervals in the circumferential direction is also conceivable. When four magnets are arranged in this manner, the magnetic force lines 155 are directed to the adjacent magnets, so that the magnetic sensor 24 may not be able to detect the magnetic force lines. Therefore, in the sending ribbon core 50, only the two magnets 52 and 54 are arranged at positions facing each other.

  With reference to FIG. 5 and FIG. 6, an example of the manufacturing method of a ribbon core is demonstrated.

  FIG. 5 is a perspective view showing a method for manufacturing a ribbon core. FIG. 6 is a schematic diagram showing a technique for identifying the magnet of the ribbon core. In these drawings, the same components as those shown in FIG. 3 are denoted by the same reference numerals.

  As shown in FIG. 5, the delivery ribbon core 50 includes a nonmagnetic, cylindrical inner core 58 and an outer core 59. The outer diameter of the inner core 58 is slightly smaller than the inner diameter of the outer core 59, and the heights of the two cores 58 and 59 are substantially equal. The inner core 58 is formed with a recess 58a to which the first magnet 52 is attached and a recess (not shown) to which the second magnet 54 is attached. The first magnet 52 is affixed to the recess 58a, the second magnet 54 is also affixed to the recess, and the inner core 58 is then covered with the outer core 59. As a result, the delivery ribbon core 50 in which the first magnet 52 and the second magnet 54 are fixed is manufactured, and the delivery ribbon core 50 in which only the predetermined portion and the opposite portion are magnetized is obtained.

  Moreover, the 1st magnet 52 and the 2nd magnet 54 cannot be normally distinguished visually. In order to make the first magnet 52 and the second magnet 54 easily distinguishable visually, as shown in FIG. 6, both the first magnet 52 and the second magnet 54 are subjected to embossing on the surface on the N pole side. Apply nothing to the surface on the S pole side. Thereby, even if the 1st magnet 52 and the 2nd magnet 54 are abundantly mixed, incorrect assembly is prevented.

  With reference to FIG. 7 and FIG. 8, a method of winding the ink ribbon around the ribbon core having the configuration shown in FIG. 5 will be described.

  7A and 7B schematically show a method of winding an ink ribbon around the ribbon core having the configuration shown in FIG. 5, wherein FIG. 7A is a front view and FIG. 7B is a side view. FIG. 8 schematically shows a method of winding an ink ribbon around a ribbon core of an ink ribbon unit of a comparative example, where (a) is a front view and (b) is a side view.

  When the ink ribbon 42 (see FIG. 1) is wound around the delivery ribbon core 50, a long long core 159 in which a plurality of outer cores 59 are connected, and a wide ink ribbon having a width similar to the length of the long core 159. 142 is prepared. While rotating the long core 159 with a rotating device (not shown) or the like and cutting the width of the wide ink ribbon 142 to be the width of the ink ribbon 42, the ink ribbon 42 is wound around the outer peripheral surface of the long core 159. To go. After winding a predetermined amount of the ink ribbon 42, the long core 159 around which the ink ribbon 42 is wound is divided so as to have the length of the outer core 59. Thereby, the some outer core 59 is obtained easily. Thereafter, by combining as described with reference to FIG. 5, the delivery ribbon core 50 around which the ink ribbon 42 is wound can be easily manufactured.

  On the other hand, as shown in FIG. 8, when the outer core 69 having the flange 69a is used, the wide ink ribbon 142 is cut by a width corresponding to the plate thickness t of the flange 69a and discarded to the long core 169. Wrap. For this reason, the part which the wide ink ribbon 142 throws away increases, and the flange 69a becomes an obstacle, and working efficiency falls.

  A technique for determining clogging of the ink ribbon will be described with reference to FIGS.

  FIG. 9 is a block diagram illustrating a jam determination unit for determining clogging of an ink ribbon. FIG. 10 is a flowchart illustrating an example of a procedure for determining clogging of the ink ribbon.

  The jam determination unit 200 measures the time from when the magnetic field is detected by the pulse generator 202 that generates pulses at regular time intervals and when the magnetic sensor 24 (see FIG. 1 etc.) detects the magnetic field lines. , A pulse counter 206 for counting the pulses generated by the pulse generator 202 within the time measured by the time measuring device 204, the magnetic sensor 24, and the like. The pulse generator 202, the time measuring device 204, and the pulse counter 206 are built in the main body of the printer 10 (see FIG. 1 and the like). An example of the number of pulses generated by the pulse generator 202 at a constant time interval is, for example, one sending ribbon core 50 in a state where the ink ribbon 42 (see FIG. 1) is wound to the maximum (the ink ribbon is not used). One example is 1500 pulses generated during the rotation time.

  A signal carrying that the magnetic sensor 24 (see FIG. 1 and the like) has detected the magnetic force line 51 is sent to the CPU 208, and the CPU 208 drives the pulse counter 206 based on this signal. Further, when it is determined that the ink ribbon 42 is clogged (when a jam occurs), the CPU 208 causes the operation unit 210 to display “Jam occurrence”.

  As an example of determining the clogging of the ink ribbon, the determination is made based on the time from when the magnetic sensor 24 detects the magnetic force line 51 (see FIG. 3 and the like) until the next detection of the magnetic force line 51. This time is measured by the time measuring device 204. In the case of the feeding ribbon core 50, the rotation speed is slow because there are many ink ribbons 42 at the beginning of use, but the rotation speed gradually increases as it is used. On the other hand, when the ink ribbon 42 is clogged, the ink ribbon 42 becomes difficult to be conveyed, and the rotational speed of the sending ribbon core 50 becomes slow. Therefore, it is possible to determine whether the ink ribbon 42 is clogged based on the above time.

  When the winding ribbon core 60 is provided with the first magnet 52 and the second magnet 54 and the magnetic sensor 24 is disposed therein to determine whether the ink ribbon 42 is clogged, the reverse is the case with the feeding ribbon core 50. . At the beginning of use of the take-up ribbon core 60, since the ink ribbon 42 is not present, the rotation speed is high. However, as the ink ribbon 42 is used, the rotation speed is gradually reduced. On the other hand, when the ink ribbon 42 is clogged, the ink ribbon 42 becomes difficult to be transported, and the rotation speed of the winding ribbon core 60 suddenly decreases. Therefore, it is possible to determine whether the ink ribbon 42 is clogged based on the above time.

  Another example of determining clogging of the ink ribbon will be described with reference to FIG.

  This flow is started when the printer 10 is turned on, the main motor rotates, and the sending ribbon core 50 starts to rotate. When the printer 10 is turned on, the pulse generator 202, the time measuring device 204, the pulse counter 206, the CPU 208, the magnetic sensor 24, and the like are driven. Here, it is assumed that the above-described bipolar detection type magnetic sensor 24 is used. In addition, the pulse counter 206 counts the pulse every time during which the delivery ribbon core 50 makes a half rotation. Further, here, the pulse generator 202 generates 1500 pulses during the time that the ribbon core for delivery 50 in a state where the ink ribbon 42 (see FIG. 1) is wound to the maximum (the ink ribbon is not used) is rotated once. It was.

  First, the pulse counter 206 counts the number of pulses in the time from when the sending ribbon core 50 starts to rotate to half rotation, and determines whether this number of pulses is 1500 or more (S1001). If the number of pulses is 1500 or more, the ink ribbon 42 (or print medium) is clogged (jammed) because it is slower than the rotational speed of the sending ribbon core 50 around which the ink ribbon 42 is wound as much as possible. It is determined that there is a possibility (S1002), the main motor is stopped (S1003), and the operation unit 210 is displayed to check the ink ribbon cassette 40 (S1004).

  If it is determined in S1001 that the number of pulses is less than 1500, it is considered that the ink ribbon 42 is gradually sent out and the rotational speed of the sending ribbon core 50 is increased, and this value is stored in the memory 210 (S1005). ). Subsequently, it is determined whether or not magnetic lines of force have been detected by the magnetic sensor 24 (S1006). That is, it is determined whether or not the delivery ribbon core 50 has rotated once since it started rotating. If it is determined in S1006 that the rotation is not completed, the process returns to S1001. If it is determined in S1006 that the rotation has been made once, the number of pulses counted in the time from when the sending ribbon core 50 starts to rotate to the half rotation (previous count), and then a further half rotation after the half rotation. The number of pulses counted until this time (the current count) is compared. This comparison is performed by the CPU 208. Subsequently, it is determined whether or not the difference between the current count number and the previous count number ((previous count number) − (current count number)) is 100 or more (S1007). When the value is 100 or more, the rotational speed of the sending ribbon core 50 is rapidly reduced, and it is considered that a jam has occurred in the ink ribbon 42. Therefore, the process proceeds to S1002, and S1003 and S1004 are executed.

  If it is determined in S1007 that the number is less than 100, it can be determined that no jam has occurred in the ink ribbon 42 and the sending ribbon core 50 is rotating normally. In this case, the current count number is stored in the memory 210 (S1008), the current count number is set as the previous count number, and the pulse counted during the time until returning to S1001 and the sending ribbon core 50 further makes a half rotation is obtained. It is determined whether the number is 1500 or more.

  As described above, jamming (clogging) of the ink ribbon 42 can also be determined by detecting the magnetic force lines 51 using the magnetic sensor 24.

DESCRIPTION OF SYMBOLS 10 Printer 24 Magnetic sensor 24a Detection element 50 Sending ribbon core 50a Inner peripheral surface 50b of sending ribbon core Outer peripheral surface 51 of sending ribbon core Magnetic field line 52 First magnet 54 Second magnet

Claims (6)

In an ink ribbon cassette comprising an ink ribbon for forming an image on a recording medium and a cylindrical ribbon core around which the ink ribbon is wound,
An ink ribbon cassette comprising a first magnet and a second magnet for generating lines of magnetic force, which are arranged on the inner peripheral surface of the ribbon core and are opposed to each other at a center portion in the height direction of the ribbon core. . The ribbon core is composed of a cylindrical outer core around which an ink ribbon is wound, and a cylindrical inner core mounted inside the outer core,
The ink ribbon cassette according to claim 1, wherein the first and second magnets are attached to an outer peripheral surface of the inner core. The first magnet is attached to a fixed portion of the outer peripheral surface of the inner core,
The ink ribbon cassette according to claim 2, wherein the second magnet is attached to a portion of the outer peripheral surface of the inner core facing the fixed portion. In a printer that forms an image on a recording medium by pressing a thermal head on the outer peripheral surface of the platen roller via a recording medium and an ink ribbon.
An ink ribbon for forming an image on a recording medium;
A ribbon core composed of a cylindrical outer core around which the ink ribbon is wound and a cylindrical inner core mounted on the inner side of the outer core;
A rotating shaft for rotating the ribbon core;
A first magnet and a second magnet for generating lines of magnetic force in a space surrounded by the inner peripheral surface of the ribbon core;
A magnetic sensor that is disposed inside the inner peripheral surface of the inner core and detects the lines of magnetic force only when the magnetic lines of force generated by the first and second magnets are in a predetermined direction due to the rotation of the ribbon core. ,
The printer according to claim 1, wherein the first and second magnets are attached to a central portion in a height direction of the cylindrical ribbon core. The ribbon core is composed of a cylindrical outer core around which an ink ribbon is wound, and a cylindrical inner core mounted inside the outer core,
The printer according to claim 4, wherein the first and second magnets are attached to an outer peripheral surface of the inner core. The first magnet is attached to a fixed portion of the outer peripheral surface of the inner core,
The printer according to claim 5, wherein the second magnet is attached to a portion of the outer peripheral surface of the inner core that faces the fixed portion.

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