JP2000211225A - Ink ribbon cassette - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ink ribbon cassette to which an appropriate back tension is given, solving the problem of printing failures, and which can be easily assembled. SOLUTION: The ink ribbon cassette 10 includes a pair of a winding out core and a winding in core housed therein, a recess part 19 defined for the insertion of a printing head, a wind-driving roller 23 adapted for the supplement of traveling of the ink ribbon between the printing head insertion recess part 19 and the winding core in the pass line of an ink ribbon 12, and a winding out stopping roller set between the winding out core and the printing head insertion recess part 19, in which at least one guide roller is furnished between the winding out core and the winding out stopping roller 16, and a first guide roller is arranged such that a holding angle of the ink ribbon in the first guide roller 15 at the winding out core side is reduced in the range of 140 deg. in the maximum amount and 80 deg. in the minimum amount as the ink ribbon travels from the maximum winding state to the minimum winding state in the winding out core.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink ribbon cassette mounted on a carriage of a printer and used for printing on a predetermined recording medium in cooperation with a print head of the printer.

2. Description of the Related Art Conventionally, a pair of rotatable cores are housed in a cassette body, and an ink ribbon is wound between these cores, one of which is an unwinding core and the other of which is a winding core. The configuration is known (for example, see Japanese Patent Application Laid-Open No. 6-48003). In this ink ribbon cassette, a concave portion for inserting a print head is provided at one longitudinal edge of the cassette body,
The ink ribbon is drawn out of the cassette body when passing through the concave portion in the pass line, and prints on a recording medium in cooperation with a print head inserted into the concave portion. In such an ink ribbon cassette, when the take-up core is fitted on a take-up bobbin of the carriage and is driven to rotate together with the take-up bobbin when the ink ribbon cassette is mounted on a carriage of the printer, the ink ribbon is taken up from the take-up core. Run along the above pass line toward Tori Core,
In order to stabilize the running of the ink ribbon and prevent meandering and printing defects, and to prevent thickening (the phenomenon that the ink ribbon is wound up with the winding core loosened), it is necessary to apply back tension to the ink ribbon. Required. In a conventional ink ribbon cassette, generally, a felt sheet is interposed between the bottom surface of the cassette main body and the unwinding core so that the ink ribbon is unwound from the unwinding core while being in contact with the sheet, thereby providing a back tension. Or the back tension is given by contacting the spring in the pass line of the ink ribbon. Further, in the ink ribbon cassette described in JP-A-6-48003, both the unwinding side and the winding side ribbon feed rollers are drive rollers, and the embedment angle of the ink ribbon in these drive rollers is increased. From the beginning to the end of the winding, a fixed angle equal to or more than the drive limit (210 degrees or more in the embodiment) is maintained. For this purpose, a guide roller is provided between the core and the drive roller on the unwinding side and the take-up side, and the ink ribbon is wound around the guide roller so that the holding angle at the drive roller is always constant. I have.

However, it is not preferable to use a felt sheet or a spring to provide the back tension, since this increases the manufacturing cost of the ink ribbon cassette. The present inventors have conducted experiments and studies on applying an appropriate back tension to the ink ribbon without using a felt sheet or a spring, and as a result, the head portion, the winding core and the unwinding core were formed on the pass line of the ink ribbon. While the winding roller of the pair of rollers provided between the rollers is a driving roller, the running of the ink ribbon is positively assisted, while the unwinding roller is not driven and is also driven by the running of the ink ribbon. The inventor has found that a back tension can be effectively applied to the ink ribbon by using a stop roller that maintains a stop state without being driven to rotate. Further, in the configuration in which the unwinding stop roller and the winding drive roller are provided, the unwinding roller is unwound from the unwinding core, rather than the wrapping angle of the ink ribbon in the unwinding roller as described in the related art. It was found that the holding angle of the ink ribbon at the first guide roller where the ink ribbon comes into contact greatly affects the back tension. However, a large back tension can be given by increasing the holding angle of the guide roller.However, if the guide roller is arranged so as to give a large holding angle, it is necessary to pass the ink ribbon through an acute pass line, and the assembly work is difficult. Not only becomes difficult, but also the seam portion with the end tape, which indicates that the end of the ink ribbon is near, may be caught when passing through the guide roller, causing the ribbon to break. In the above-mentioned prior art, the holding angle of the ink ribbon in the guide roller provided between the unwinding core and the unwinding side roller is about 160 degrees in the drawing. The problem was noticeable. Also,
When the guide roller is arranged so as to provide a hugging angle of 160 degrees when the unwinding side is a stop roller, running failure may be caused.

SUMMARY OF THE INVENTION Accordingly, the present invention solves the above-mentioned problems in the prior art, and provides an appropriate back tension to the ink ribbon without making the assembly operation of the ink ribbon cassette difficult and at low cost. It is an object of the present invention to provide a novel ink ribbon cassette capable of stabilizing traveling. That is, in the ink ribbon cassette according to the present invention, the pair of unwinding core and the winding core around which the ink ribbon is wound are housed in the cassette body, and the print head is inserted into one longitudinal edge of the cassette body. A recess is provided, and a winding drive assists the running of the ink ribbon between the print head insertion recess and the take-up core in a pass line of the ink ribbon from the unwinding core to the take-up core through the print head insertion recess. A roller is provided and an unwind stop roller is provided between the unwind core and the print head insertion recess, and at least one guide roller is provided between the unwind core and the unwind stop roller, The holding angle of the ink ribbon in the first guide roller on the unwinding core side is up to 140 degrees as the ink ribbon in the unwinding core changes from the maximum winding state to the minimum winding state.
The first guide roller is arranged so as to decrease in a range of a minimum of 80 degrees. The ink ribbon holding angle (α) of the first guide roller when the ink ribbon is wound around the unwinding core is preferably 100 degrees or more, and more preferably 120 degrees or more. On the other hand, the ink ribbon holding angle (β) of the first guide roller when the ink ribbon is wound minimum on the unwinding core is preferably 90 degrees or less, and the material of the winding drive roller is preferably a thermoplastic elastomer. Yes,
The material of the unwind stop roller is preferably any one selected from the group consisting of ABS (acrylonitrile butadiene styrene), AS (acrylonitrile styrene), PS (polystyrene), PC (polycarbonate), and POM (polyacetal). Instead of the unwind stop roller, an unwind stop pin or a fixing member having a guide surface for guiding the running of the ink ribbon may be used.

FIG. 1 shows an ink ribbon cassette 10 according to an embodiment of the present invention. In order to show the internal mechanism, FIG. 1 shows the ink ribbon cassette 10 in a state where the cover is removed from a cassette body formed by joining the case 11 and the cover. In a case 11, a pair of cores 13, 1 around which an ink ribbon 12 is wound is provided.
4, the core 13 is an unwinding core and the core 14 is a winding core in the state of FIG. Ink ribbon 1
2 is guided from the unwinding core 13 by a guide roller 15, an unwinding stop roller 16, and guide rollers 17 and 18, and protrudes from both sides of a concave portion 19 formed at the center of one longitudinal edge of the case 11. After being guided to the tip of one of the tapered projections 20, 21, the tapered projection 20, 21 is led out of the cassette body toward the recess 19. The ink ribbon 12 guided by the tip of the other protrusion 21 and introduced again into the cassette main body includes a guide roller 22, a take-up drive roller 23, and a guide roller 24.
And wound on the winding core 14. Thus, the pass line of the ink ribbon 12 from the unwinding core 13 to the winding core 14 is defined. In a state in which the ink ribbon cassette 10 is loaded on the carriage of the thermal transfer printer, a pair of bobbins on the carriage are respectively fitted to the unwinding core 13 and the winding core 14, and the winding bobbin fitted to the winding core 14. Is rotated by an appropriate driving source, so that the ink ribbon 12 is sent from the unwinding core 13 to the winding core 14 through the above-described pass line, and the unwinding core 13 is also wound up. The core 14 is driven and rotated in the same direction as the rotational driving direction. The thermal head provided so as to be able to reciprocate along the platen together with the carriage is inserted into the concave portion 19 of the ink ribbon cassette 10, and moves upward in FIG. The ink ribbon 12 is pulled up, and predetermined printing is performed on a predetermined recording medium conveyed in synchronization with the travel of the ink ribbon 12. Such a configuration on the printer side and a printing mechanism based on the thermal transfer method are known, and are not shown in the drawings and will be described only briefly. Guide rollers 15, 1
Reference numerals 7, 18, 22 and 24 denote free rollers which are rotatably provided.
The ink ribbon 12 rotates as the ink ribbon 12 runs due to friction between the second non-printing surface (backcoat surface) or the printing surface.
The unwind stop roller 16 and the take-up driving roller 23 serve to guide the ink ribbon 12 to travel along a predetermined pass line together with the guide rollers 15, 17, 18, 22 and 24, Reference numeral 23 denotes an ink ribbon which rotates counterclockwise in FIG. 1 by receiving a driving force when the drive shaft (not shown) on the carriage side is rotationally driven by being fitted in the loaded state. Actively assists the running of Twelve. On the other hand, the unwind stop roller 16 is not not only driven to rotate positively, but also maintains a substantially stopped state without being drivenly rotated with the running of the ink ribbon 12, so that the unwinding roller 16 is driven backward with respect to the running ink ribbon 12. Give tension. The material of the take-up driving roller 23 is preferably a thermoplastic elastomer, particularly an olefin-based thermoplastic elastomer (TP).
O) having a Shore hardness (D) of 40 or more, more preferably 45 to 50, is suitably used. The material of the unwind stop roller is preferably any one selected from the group consisting of ABS (acrylonitrile butadiene styrene), AS (acrylonitrile styrene), PS (polystyrene), PC (polycarbonate), and POM (polyacetal). Here, the guide roller 15 provided between the unwinding core 13 and the unwinding stop roller 16 serves as the unwinding core 13 as the ink ribbon 12 is unwound.
The angle of hugging changes. That is, the state in which the ink ribbon 1 is completely wound around the unwinding core 13 (the ink ribbon 1 in the unwinding core 13).
2 has a maximum embroidering angle in the initial state where the winding diameter is maximum (indicated by a solid line in FIG. 1), and the embracing angle gradually decreases as the ink ribbon 12 is unwound from this state. Is fully wound around the take-up core 17 (a state in which the winding diameter of the ink ribbon in the unwinding core 13 is minimum, and is indicated by a virtual line in FIG. 1), the holding angle of the guide roller 15 is minimum. However, the angle at which the ink ribbon 12 is held by the guide roller 15 is 80 degrees.
It is preferable to arrange the guide roller 15 so as to change within a range of up to 140 degrees. In the embodiment, as shown in FIG. 2, when the unwinding core 13 has the maximum winding diameter, the holding angle (α) of the ink ribbon 12max held by the guide roller 15 is about 138 degrees, and the ink at the minimum winding diameter is Ribbon 12m
The guide roller 15 is arranged so that the holding angle (β) of “in” is about 87 degrees. The ink ribbon cassette is shipped in a state of being fully wound around the unwinding core 13. At this time, if the holding angle (α) of the guide roller 15 is too large, it is difficult to bridge the ink ribbon, and the efficiency of assembling the ink ribbon cassette is reduced. It will drop significantly. From this viewpoint, the holding angle (α) is required not to exceed 140 degrees. On the other hand, if the holding angle of the guide roller 15 is too small, it is difficult to give an appropriate back tension to the running of the ink ribbon, which causes printing failure. Therefore, the minimum value (β) of the holding angle is at least 80. Degree is required. Furthermore, at the beginning of printing, the rotation angle of the unwinding core 13 is relatively small, and
Since sufficient back tension cannot be applied to the ink ribbon 12 depending on the friction caused by the rotation of the third roller 3, the holding angle (α) of the guide roller 15 at this time is used.
It is necessary to complement the back tension by making it somewhat large. From this viewpoint, the holding angle (α) is preferably 100 degrees or more, and more preferably 120 degrees or more. Further, at the end of printing, an end tape (not shown) indicating that the end of the ink ribbon 12 is near passes through the guide roller 15, but if the holding angle at this time is large, a seam with the end tape is caught and easily peeled. Therefore, the holding angle (β) is preferably set to 90 degrees or less. Although one embodiment of the present invention has been described in detail above, the present invention is not limited to this embodiment, and various modifications can be made within the scope of the invention described in the claims. For example, the unwinding stop roller 16 is used in the configuration of FIG. 1, but as described above, this member substantially maintains the stopped state during its travel to apply back tension to the ink ribbon 12. Therefore, the fixing member does not necessarily have to have a roller shape, and may be a pin shape or another shape, for example, a fixing member having an arcuate guide surface for guiding the travel of the ink ribbon 12.

According to the present invention, an appropriate back tension can be applied to the ink ribbon traveling from the unwinding core to the winding core, and the ink ribbon can be stably run on a predetermined pass line. Therefore, printing defects such as voids can be prevented. In the present invention, a special member such as a felt sheet or a spring is not required to provide the back tension, and since the unwinding-side roller is a non-driving fixed member, the configuration of the driving system is also simplified. The manufacturing cost of the ink ribbon cassette can be reduced. Further, since the guide roller provided between the unwinding core and the unwinding stop roller does not need to have an excessively large embrace angle with respect to the ink ribbon, the assembly work of the ink ribbon cassette does not become troublesome, and there is also a problem such as ribbon breakage. There is an advantage that it does not occur.

[Brief description of the drawings]

FIG. 1 is a top view showing the internal structure of an ink ribbon cassette according to one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a change in a pass line and a holding angle of an ink ribbon in a first guide roller on an unwinding core side.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Ink ribbon cassette 11 Case 12 Ink ribbon 12max Ink ribbon pass line at the time of maximum winding to an unwinding core 12min Ink ribbon pass line at the time of minimum winding to an unwinding core 13 Unwinding core 14 Take-up core 15, 17, 18, 22, 24 Guide roller 15 First guide roller on unwinding core side 16 Unwinding stop roller 23 Take-up driving roller 19 Head insertion recess 20, 21 Projection α Maximum holding angle of ink ribbon in guide roller 15 β Minimum holding angle of ink ribbon on guide roller 15

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[Procedure amendment]

[Submission date] February 9, 1999 (1999.2.9)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

[Title of the Invention] Ink ribbon cassette

[Claims]

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink ribbon cassette mounted on a carriage of a printer and used for printing on a predetermined recording medium in cooperation with a print head of the printer.

2. Description of the Related Art Conventionally, a pair of rotatable cores are housed in a cassette body, and an ink ribbon is wound between these cores, one of which is an unwinding core and the other of which is a winding core. The configuration is known (for example, see Japanese Patent Application Laid-Open No. 6-48003). In this ink ribbon cassette, a concave portion for inserting a print head is provided at one longitudinal edge of the cassette body,
The ink ribbon is drawn out of the cassette body when passing through the concave portion in the pass line, and prints on a recording medium in cooperation with a print head inserted into the concave portion. In such an ink ribbon cassette, when the take-up core is fitted on a take-up bobbin of the carriage and is driven to rotate together with the take-up bobbin when the ink ribbon cassette is mounted on a carriage of the printer, the ink ribbon is taken up from the take-up core. Run along the above pass line toward Tori Core,
In order to stabilize the running of the ink ribbon and prevent meandering and printing defects, and to prevent thickening (the phenomenon that the ink ribbon is wound up with the winding core loosened), it is necessary to apply back tension to the ink ribbon. Required. In a conventional ink ribbon cassette, generally, a felt sheet is interposed between the bottom surface of the cassette main body and the unwinding core so that the ink ribbon is unwound from the unwinding core while being in contact with the sheet, thereby providing a back tension. Or the back tension is given by contacting the spring in the pass line of the ink ribbon. Further, in the ink ribbon cassette described in JP-A-6-48003, both the unwinding side and the winding side ribbon feed rollers are drive rollers, and the embedment angle of the ink ribbon in these drive rollers is increased. From the beginning to the end of the winding, a fixed angle equal to or more than the drive limit (210 degrees or more in the embodiment) is maintained. For this purpose, a guide roller is provided between the core and the drive roller on the unwinding side and the take-up side, and the ink ribbon is wound around the guide roller so that the holding angle at the drive roller is always constant. I have.

However, it is not preferable to use a felt sheet or a spring to provide the back tension, since this increases the manufacturing cost of the ink ribbon cassette. The present inventors have conducted experiments and studies on applying an appropriate back tension to the ink ribbon without using a felt sheet or a spring, and as a result, the head portion, the winding core and the unwinding core were formed on the pass line of the ink ribbon. While the winding roller of the pair of rollers provided between the rollers is a driving roller, the running of the ink ribbon is positively assisted, while the unwinding roller is not driven and is also driven by the running of the ink ribbon. The inventor has found that a back tension can be effectively applied to the ink ribbon by using a stop roller that maintains a stop state without being driven to rotate. Further, in the configuration in which the unwinding stop roller and the winding drive roller are provided, the unwinding roller is unwound from the unwinding core, rather than the wrapping angle of the ink ribbon in the unwinding roller as described in the related art. It was found that the holding angle of the ink ribbon at the first guide roller where the ink ribbon comes into contact greatly affects the back tension. However, a large back tension can be given by increasing the holding angle of the guide roller.However, if the guide roller is arranged so as to give a large holding angle, it is necessary to pass the ink ribbon through an acute pass line, and the assembly work is difficult. Not only becomes difficult, but also the seam portion with the end tape, which indicates that the end of the ink ribbon is near, may be caught when passing through the guide roller, causing the ribbon to break. In the above-mentioned prior art, the holding angle of the ink ribbon in the guide roller provided between the unwinding core and the unwinding side roller is about 160 degrees in the drawing. The problem was noticeable. Also,
When the guide roller is arranged so as to provide a hugging angle of 160 degrees when the unwinding side is a stop roller, running failure may be caused.

SUMMARY OF THE INVENTION Accordingly, the present invention solves the above-mentioned problems in the prior art, and provides an appropriate back tension to the ink ribbon without making the assembly operation of the ink ribbon cassette difficult and at low cost. It is an object of the present invention to provide a novel ink ribbon cassette capable of stabilizing traveling. That is, in the ink ribbon cassette according to the present invention, the pair of unwinding core and the winding core around which the ink ribbon is wound are housed in the cassette body, and the print head is inserted into one longitudinal edge of the cassette body. A recess is provided, and a winding drive assists the running of the ink ribbon between the print head insertion recess and the take-up core in a pass line of the ink ribbon from the unwinding core to the take-up core through the print head insertion recess. A roller is provided and an unwind stop roller is provided between the unwind core and the print head insertion recess, and at least one guide roller is provided between the unwind core and the unwind stop roller, The holding angle of the ink ribbon in the first guide roller on the unwinding core side is up to 140 degrees as the ink ribbon in the unwinding core changes from the maximum winding state to the minimum winding state.
The first guide roller is arranged so as to decrease in a range of a minimum of 80 degrees. The ink ribbon holding angle (α) of the first guide roller when the ink ribbon is wound around the unwinding core is preferably 100 degrees or more, and more preferably 120 degrees or more. On the other hand, the ink ribbon holding angle (β) of the first guide roller when the ink ribbon is wound minimum on the unwinding core is preferably 90 degrees or less, and the material of the winding drive roller is preferably a thermoplastic elastomer. Yes,
The material of the unwind stop roller is preferably any one selected from the group consisting of ABS (acrylonitrile butadiene styrene), AS (acrylonitrile styrene), PS (polystyrene), PC (polycarbonate), and POM (polyacetal). Instead of the unwind stop roller, an unwind stop pin or a fixing member having a guide surface for guiding the running of the ink ribbon may be used.

FIG. 1 shows an ink ribbon cassette 10 according to an embodiment of the present invention. In order to show the internal mechanism, FIG. 1 shows the ink ribbon cassette 10 in a state where the cover is removed from a cassette body formed by joining the case 11 and the cover. In a case 11, a pair of cores 13, 1 around which an ink ribbon 12 is wound is provided.
4, the core 13 is an unwinding core and the core 14 is a winding core in the state of FIG. Ink ribbon 1
2 is guided from the unwinding core 13 by a guide roller 15, an unwinding stop roller 16, and guide rollers 17 and 18, and protrudes from both sides of a concave portion 19 formed at the center of one longitudinal edge of the case 11. After being guided to the tip of one of the tapered projections 20, 21, the tapered projection 20, 21 is led out of the cassette body toward the recess 19. The ink ribbon 12 guided by the tip of the other protrusion 21 and introduced again into the cassette main body includes a guide roller 22, a take-up drive roller 23, and a guide roller 24.
And wound on the winding core 14. Thus, the pass line of the ink ribbon 12 from the unwinding core 13 to the winding core 14 is defined. In a state in which the ink ribbon cassette 10 is loaded on the carriage of the thermal transfer printer, a pair of bobbins on the carriage are respectively fitted to the unwinding core 13 and the winding core 14, and the winding bobbin fitted to the winding core 14. Is rotated by an appropriate driving source, so that the ink ribbon 12 is sent from the unwinding core 13 to the winding core 14 through the above-described pass line, and the unwinding core 13 is also wound up. The core 14 is driven and rotated in the same direction as the rotational driving direction. The thermal head provided so as to be able to reciprocate along the platen together with the carriage is inserted into the concave portion 19 of the ink ribbon cassette 10, and moves upward in FIG. The ink ribbon 12 is pulled up, and predetermined printing is performed on a predetermined recording medium conveyed in synchronization with the travel of the ink ribbon 12. Such a configuration on the printer side and a printing mechanism based on the thermal transfer method are known, and are not shown in the drawings and will be described only briefly. Guide rollers 15, 1
Reference numerals 7, 18, 22 and 24 denote free rollers which are rotatably provided.
The ink ribbon 12 rotates as the ink ribbon 12 runs due to friction between the second non-printing surface (backcoat surface) or the printing surface.
The unwind stop roller 16 and the take-up driving roller 23 serve to guide the ink ribbon 12 to travel along a predetermined pass line together with the guide rollers 15, 17, 18, 22 and 24, Reference numeral 23 denotes an ink ribbon which rotates counterclockwise in FIG. 1 by receiving a driving force when the drive shaft (not shown) on the carriage side is rotationally driven by being fitted in the loaded state. Actively assists the running of Twelve. On the other hand, the unwind stop roller 16 is not not only driven to rotate positively, but also maintains a substantially stopped state without being drivenly rotated with the running of the ink ribbon 12, so that the unwinding roller 16 is driven backward with respect to the running ink ribbon 12. Give tension. The material of the take-up driving roller 23 is preferably a thermoplastic elastomer, particularly an olefin-based thermoplastic elastomer (TP).
O) having a Shore hardness (D) of 40 or more, more preferably 45 to 50, is suitably used. The material of the unwind stop roller is preferably any one selected from the group consisting of ABS (acrylonitrile butadiene styrene), AS (acrylonitrile styrene), PS (polystyrene), PC (polycarbonate), and POM (polyacetal). Here, the guide roller 15 provided between the unwinding core 13 and the unwinding stop roller 16 serves as the unwinding core 13 as the ink ribbon 12 is unwound.
The angle of hugging changes. That is, the state in which the ink ribbon 1 is completely wound around the unwinding core 13 (the ink ribbon 1 in the unwinding core 13).
2 has a maximum embroidering angle in the initial state where the winding diameter is maximum (indicated by a solid line in FIG. 1), and the embracing angle gradually decreases as the ink ribbon 12 is unwound from this state. Is fully wound around the take-up core 17 (a state in which the winding diameter of the ink ribbon in the unwinding core 13 is minimum, and is indicated by a virtual line in FIG. 1), the holding angle of the guide roller 15 is minimum. However, the angle at which the ink ribbon 12 is held by the guide roller 15 is 80 degrees.
It is preferable to arrange the guide roller 15 so as to change within a range of up to 140 degrees. In the embodiment, as shown in FIG. 2, when the unwinding core 13 has the maximum winding diameter, the holding angle (α) of the ink ribbon 12max held by the guide roller 15 is about 138 degrees, and the ink at the minimum winding diameter is Ribbon 12m
The guide roller 15 is arranged so that the holding angle (β) of “in” is about 87 degrees. The ink ribbon cassette is shipped in a state of being fully wound around the unwinding core 13. At this time, if the holding angle (α) of the guide roller 15 is too large, it is difficult to bridge the ink ribbon, and the efficiency of assembling the ink ribbon cassette is reduced. It will drop significantly. From this viewpoint, the holding angle (α) is required not to exceed 140 degrees. On the other hand, if the holding angle of the guide roller 15 is too small, it is difficult to give an appropriate back tension to the running of the ink ribbon, which causes printing failure. Therefore, the minimum value (β) of the holding angle is at least 80. Degree is required. Furthermore, at the beginning of printing, the rotation angle of the unwinding core 13 is relatively small, and
Since sufficient back tension cannot be applied to the ink ribbon 12 depending on the friction caused by the rotation of the third roller 3, the holding angle (α) of the guide roller 15 at this time is used.
It is necessary to complement the back tension by making it somewhat large. From this viewpoint, the holding angle (α) is preferably 100 degrees or more, and more preferably 120 degrees or more. Further, at the end of printing, an end tape (not shown) indicating that the end of the ink ribbon 12 is near passes through the guide roller 15, but if the holding angle at this time is large, a seam with the end tape is caught and easily peeled. Therefore, the holding angle (β) is preferably set to 90 degrees or less. Although one embodiment of the present invention has been described in detail above, the present invention is not limited to this embodiment, and various modifications can be made within the scope of the invention described in the claims. For example, the unwinding stop roller 16 is used in the configuration of FIG. 1, but as described above, this member substantially maintains the stopped state during its travel to apply back tension to the ink ribbon 12. Therefore, the fixing member does not necessarily have to have a roller shape, and may be a pin shape or another shape, for example, a fixing member having an arcuate guide surface for guiding the travel of the ink ribbon 12.

According to the present invention, an appropriate back tension can be applied to the ink ribbon traveling from the unwinding core to the winding core, and the ink ribbon can be stably run on a predetermined pass line. Therefore, printing defects such as voids can be prevented. In the present invention, a special member such as a felt sheet or a spring is not required to provide the back tension, and since the unwinding-side roller is a non-driving fixed member, the configuration of the driving system is also simplified. The manufacturing cost of the ink ribbon cassette can be reduced. Further, since the guide roller provided between the unwinding core and the unwinding stop roller does not need to have an excessively large embrace angle with respect to the ink ribbon, the assembly work of the ink ribbon cassette does not become troublesome, and there is also a problem such as ribbon breakage. There is an advantage that it does not occur.

[Brief description of the drawings]

FIG. 1 is a top view showing the internal structure of an ink ribbon cassette according to one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a change in a pass line and a holding angle of an ink ribbon in a first guide roller on an unwinding core side.

DESCRIPTION OF SYMBOLS 10 Ink ribbon cassette 11 Case 12 Ink ribbon 12max Ink ribbon pass line when wound maximally on unwinding core 12min Ink ribbon pass line when winded minimum on unwinding core 13 Unwinding core 14 Take-up cores 15, 17, 18, 22, 24 Guide rollers 15 First guide roller on the take-out core side 16 Unwind stop roller 23 Take-up drive roller 19 Head insertion recess 20, 21 Projection α Ink ribbon in guide roller 15 Of the ink ribbon at the guide roller 15. ──────────────────

[Procedure amendment]

[Submission date] February 12, 1999 (1999.2.1
2)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

[Title of the Invention] Ink ribbon cassette

[Claims]

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink ribbon cassette mounted on a carriage of a printer and used for printing on a predetermined recording medium in cooperation with a print head of the printer.

[0002]

2. Description of the Related Art Conventionally, a pair of rotatable cores are housed in a cassette body, and an ink ribbon is wound between these cores, one of which is an unwinding core and the other of which is a winding core. The configuration is known (for example, see Japanese Patent Application Laid-Open No. 6-48003).

In this ink ribbon cassette, a concave portion for inserting a print head is provided at one longitudinal edge of the cassette main body, and when the ink ribbon passes through the concave portion along the pass line, the concave portion of the cassette main body is provided. It is drawn out to the outside and prints on a recording medium in cooperation with a print head inserted into the concave portion.

In such an ink ribbon cassette, when the take-up core is mounted on a carriage of a printer, the take-up core is fitted to a take-up bobbin of the carriage and is driven to rotate together with the take-up bobbin, thereby unwinding the ink ribbon. Run along the above pass line from the core to the winding core,
In order to stabilize the running of the ink ribbon and prevent meandering and printing defects, and to prevent thickening (the phenomenon that the ink ribbon is wound up with the winding core loosened), it is necessary to apply back tension to the ink ribbon. Required.

In a conventional ink ribbon cassette,
Generally, a felt sheet is interposed between the bottom surface of the cassette body and the unwinding core so that the ink ribbon is unwound from the unwinding core while being in contact with the sheet, thereby providing a back tension. The back tension is given by contacting the spring in the pass line.

In the ink ribbon cassette described in JP-A-6-48003, both the unwinding side and the winding side ribbon feed rollers are drive rollers, and the drive rollers hold the ink ribbon. The angle is equal to or larger than the drive limit from the start of winding to the end of winding (21 in the embodiment).
(0 degree or more). For this purpose, a guide roller is provided between the core and the drive roller on the unwinding side and the take-up side, and the ink ribbon is wound around the guide roller so that the holding angle at the drive roller is always constant. I have.

[0007]

However, it is not preferable to use a felt sheet or a spring to provide the back tension, since this increases the manufacturing cost of the ink ribbon cassette.

The inventors of the present invention have conducted experiments and studies on applying an appropriate back tension to the ink ribbon without using a felt sheet or a spring. As a result, the head portion, the winding core and the winding core were formed on the pass line of the ink ribbon. The drive of the ink ribbon is positively assisted by using the take-up roller as a drive roller of the pair of rollers provided between the take-out core and the take-out roller, while the take-out roller is not driven and the ink ribbon is driven. The inventor has found that a back tension can be effectively applied to the ink ribbon by using a stop roller that maintains a stopped state without being driven and rotated even by running.

Furthermore, in the configuration in which the unwind stop roller and the take-up driving roller are provided, as described in the above-mentioned prior art, the unwind angle of the ink ribbon in the unwind roller is rather than the unwind angle of the unwind core. It has been found that the angle of embrace of the ink ribbon at the first guide roller where the unwound ink ribbon comes into contact greatly affects the back tension.

However, a large back tension can be given by increasing the holding angle of the guide roller. However, if the guide roller is arranged so as to give a large holding angle, it is necessary to pass the ink ribbon through an acute pass line. Not only does the assembling work become difficult, but also the seam portion with the end tape indicating that the end of the ink ribbon is near may be caught when passing through the guide roller, and the ribbon may be cut.

In the prior art, the guide roller provided between the unwinding core and the unwinding roller has an ink ribbon holding angle of about 160 degrees in the drawing. In the above, the above-mentioned problem was remarkably exhibited. In addition, when the guide roller is arranged so as to give a hugging angle of 160 degrees when the unwinding side is a stop roller, running failure may be caused.

[0012]

SUMMARY OF THE INVENTION Accordingly, the present invention solves the above-mentioned problems in the prior art, and provides an appropriate back tension to the ink ribbon without making the assembly operation of the ink ribbon cassette difficult and at low cost. It is an object of the present invention to provide a novel ink ribbon cassette capable of stabilizing traveling.

That is, in the ink ribbon cassette according to the present invention, a pair of the unwinding core and the winding core around which the ink ribbon is wound are housed in the cassette body, and the print head is inserted into one longitudinal edge of the cassette body. A concave portion is provided between the print head insertion concave portion and the take-up core in a pass line of the ink ribbon extending from the unwinding core to the take-up core through the print head insertion concave portion. An unwinding drive roller is provided, and an unwinding stop roller is provided between the unwinding core and the print head insertion recess, and at least one guide roller is provided between the unwinding core and the unwinding stop roller. The winding angle of the ink ribbon in the first guide roller on the unwinding core side is changed as the ink ribbon in the unwinding core changes from the maximum winding state to the minimum winding state. Large 140 degrees, outermost first guide roller as slide into decreased in the range of minimum 80 ° and characterized in that disposed.

The ink ribbon holding angle (α) of the first guide roller when the ink ribbon is wound around the unwinding core at the maximum is preferably 100 degrees or more, more preferably 120 degrees or more. On the other hand, the ink ribbon holding angle (β) of the first guide roller when the ink ribbon is wound minimum on the unwinding core is preferably 90 degrees or less, and the material of the winding drive roller is preferably a thermoplastic elastomer. The material of the unwinding stop roller is preferably ABS (acrylonitrile butadiene styrene),
It is any one selected from the group consisting of AS (acrylonitrile styrene), PS (polystyrene), PC (polycarbonate) and POM (polyacetal).

Instead of the unwind stop roller, an unwind stop pin or a fixing member having a guide surface for guiding the running of the ink ribbon may be used.

[0016]

FIG. 1 shows an ink ribbon cassette 10 according to an embodiment of the present invention. In order to show the internal mechanism, FIG. 1 shows the ink ribbon cassette 10 in a state where the cover is removed from a cassette body formed by joining the case 11 and the cover.

In the case 11, a pair of cores 13 and 14 around which the ink ribbon 12 is wound are accommodated. In the state of FIG. 1, the core 13 is an unwinding core and the core 14 is a winding core. . The ink ribbon 12 is guided from the unwinding core 13 by a guide roller 15, an unwinding stop roller 16, and guide rollers 17 and 18. Further, both sides of a concave portion 19 formed at the center of one longitudinal edge of the case 11. After being guided by the tip of one of the tapered projections 20, 21 formed to project from the cassette body, it is led out of the cassette body toward the recess 19. The ink ribbon 12 guided by the tip of the other projection 21 and introduced again into the cassette main body includes a guide roller 22 and a take-up driving roller 23.
And is guided by the guide roller 24, and is wound on the winding core 14. Thus, the pass line of the ink ribbon 12 from the unwinding core 13 to the winding core 14 is defined.

When the ink ribbon cassette 10 is loaded on a carriage of a thermal transfer printer, a pair of bobbins on the carriage are provided with an unwinding core 13 and a winding core 14.
The ink ribbon 12 passes from the winding core 13 to the winding core 13 through the pass line described above, and the winding bobbin fitted to the winding core 14 is rotationally driven by an appropriate drive source. The winding core 13 is also driven and rotated in the same direction as the rotation driving direction of the winding core 14. The thermal head provided so as to be able to reciprocate along the platen together with the carriage is inserted into the concave portion 19 of the ink ribbon cassette 10, and moves upward in FIG. Pull up the ink ribbon 12,
The predetermined printing is performed on a predetermined recording medium conveyed in synchronization with the travel of the ink ribbon 12.

Since the configuration on the printer side and the printing mechanism based on the thermal transfer method are known, they are not shown in the drawings and will be described only briefly.

Each of the guide rollers 15, 17, 18, 22 and 24 is a free roller provided rotatably, and is provided between the peripheral surface thereof and the non-printing surface (back coating surface) or the printing surface of the ink ribbon 12. The ink ribbon 12 rotates as the ink ribbon 12 travels due to the friction.

The unwind stop roller 16 and the take-up driving roller 23 are guide rollers 15, 17, 18, 22 and 24.
In addition, the winding drive roller 23 serves to guide the ink ribbon 12 to travel along a predetermined pass line, and the take-up drive roller 23 is fitted with a drive shaft (not shown) on the carriage side in a loaded state. When the drive shaft is rotationally driven, it receives the driving force and rotates in the counterclockwise direction in FIG. 1 to actively assist the running of the ink ribbon 12. On the other hand, the unwind stop roller 16 is not not only driven to rotate positively, but also maintains a substantially stopped state without being drivenly rotated with the running of the ink ribbon 12, so that the unwinding roller 16 is driven backward with respect to the running ink ribbon 12. Give tension.

The take-up driving roller 23 is preferably made of a thermoplastic elastomer, particularly an olefinic thermoplastic elastomer (TPO) having a Shore hardness (D) of 40 or more, more preferably 45 to 50. Used for The material of the unwinding stop roller is preferably ABS
(Acrylonitrile butadiene styrene), AS (acrylonitrile styrene), PS (polystyrene), PC
(Polycarbonate) and POM (polyacetal)
Any one selected from the group consisting of:

Here, the unwinding core 13 and the unwinding stop roller 1
The guide angle between the guide roller 15 and the unwinding core 13 changes as the ink ribbon 12 unwinds. That is, when the winding core 13 is fully wound (the initial state in which the winding diameter of the ink ribbon 12 in the unwinding core 13 is the maximum, and is indicated by a solid line in FIG. 1), the holding angle has a maximum. Ink ribbon 1
2 is unwound, the embroidering angle gradually decreases, and the ink ribbon 12 is completely wound around the take-up core 17 (the state where the ink ribbon winding diameter of the unwind core 13 is minimum,
(Indicated by phantom lines in FIG. 1), the hugging angle of the guide roller 15 is minimized.
It is preferable to arrange the guide rollers 15 so that the holding angle of the ink ribbon 12 in the range of 80 to 140 degrees is changed. In the embodiment, as shown in FIG. 2, when the unwinding core 13 has the maximum winding diameter, the ink ribbon 12m
ax is held by the guide roller 15 at an angle (α) of about 1
The guide roller 15 is arranged so that the holding angle (β) of the ink ribbon 12 min at the time of the minimum winding diameter is about 87 degrees.

The ink ribbon cassette is shipped in a state in which it is fully wound around the unwinding core 13. If the angle (α) of the guide roller 15 at this time is too large, it is difficult to transfer the ink ribbon, and the ink ribbon cassette is assembled. Work efficiency is greatly reduced. From this viewpoint, the holding angle (α) is required not to exceed 140 degrees.

If the holding angle of the guide roller 15 is too small, it is difficult to give an appropriate back tension to the running of the ink ribbon, which causes printing failure. Therefore, the minimum value of the holding angle (β) Is required to be at least 80 degrees or more. Furthermore, in the initial stage of printing, the rotation angle of the unwinding core 13 is relatively small, and a sufficient back tension cannot be applied to the ink ribbon 12 due to the friction caused by the rotation of the unwinding core 13. It is necessary to complement the back tension by increasing the hugging angle (α) of the guide roller 15 to some extent. From this point of view, the holding angle (α) is 10
It is preferably at least 0 °, more preferably 120 °
Degrees or more.

At the end of printing, the ink ribbon 1
An end tape (not shown) indicating that the end of the tape 2 is near passes through the guide roller 15. However, if the holding angle at this time is large, the seam with the end tape is easily caught and easily peeled off. Is preferably 90 degrees or less.

Although the embodiment of the present invention has been described in detail above, the present invention is not limited to this embodiment, and various modifications can be made within the scope of the invention described in the claims. For example, the unwinding stop roller 16 is used in the configuration of FIG. 1, but as described above, this member substantially maintains the stopped state during its travel to apply back tension to the ink ribbon 12. Therefore, it is not always necessary to have a roller shape, but a pin shape or other shapes such as the ink ribbon 1.
A fixed member having an arcuate guide surface for guiding the traveling of the vehicle 2 may be used.

[0028]

According to the present invention, an appropriate back tension can be applied to the ink ribbon traveling from the unwinding core to the winding core, and the ink ribbon can be stably run on a predetermined pass line. Therefore, printing defects such as voids can be prevented.

In the present invention, a special member such as a felt sheet or a spring is not required to provide the back tension.
Further, since the unwinding-side roller is a non-driving fixed member, the configuration of the driving system is also simplified, so that the manufacturing cost of the ink ribbon cassette can be reduced.

Further, since the guide roller provided between the unwinding core and the unwinding stop roller does not need to have an excessively large angle with respect to the ink ribbon, the assembly operation of the ink ribbon cassette does not become troublesome, and the ribbon is broken. There is an advantage that the problem described above does not occur.

[Brief description of the drawings]

FIG. 1 is a top view showing the internal structure of an ink ribbon cassette according to one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a change in a pass line and a holding angle of an ink ribbon in a first guide roller on an unwinding core side.

DESCRIPTION OF SYMBOLS 10 Ink ribbon cassette 11 Case 12 Ink ribbon 12max Ink ribbon pass line when wound maximally on unwinding core 12min Ink ribbon pass line when winded minimum on unwinding core 13 Unwinding core 14 Take-up cores 15, 17, 18, 22, 24 Guide rollers 15 First guide roller on the take-out core side 16 Unwind stop roller 23 Take-up drive roller 19 Head insertion recess 20, 21 Projection α Ink ribbon in guide roller 15 Of the ink ribbon at the guide roller 15

Continued on the front page (72) Inventor Nagatake Watanabe 500 Kashimajima, Fukaya-shi, Saitama Prefecture Dynic Co., Ltd. Saitama Factory (72) Inventor Yoshiyuki Hori 500 Kajima, Fukaya-shi, Saitama Prefecture Dynic Co., Ltd. Saitama Factory F-term (reference) 2C068 AA01 AA06 AA15 EE01 EE87 FF01 FF12 FF19 GK02 GK13 HH04 HH12 HH20

Claims (7)

[Claims] A pair of unwinding and winding cores around which an ink ribbon is wound are housed in a cassette body, and a recess for inserting a print head is provided at one longitudinal edge of the cassette body. A take-up driving roller is provided between the print head insertion recess and the take-up core in a pass line of the ink ribbon from the unwinding core to the take-up core through the print head insertion recess. An unwind stop roller is provided between the unwind core and the print head insertion recess, and at least one guide roller is provided between the unwind core and the unwind stop roller. Of the ink ribbon in the first guide roller of the first embodiment decreases from a maximum of 140 degrees to a minimum of 80 degrees as the ink ribbon of the unwinding core changes from the maximum winding state to the minimum winding state. Ink ribbon cassette characterized in that the outermost first guide roller is disposed. 2. The ink ribbon cassette according to claim 1, wherein the ink ribbon holding angle (α) of the first guide roller when the ink ribbon is wound up to the unwinding core is 100 degrees or more. 3. The ink ribbon cassette according to claim 1, wherein the ink ribbon holding angle (α) of the first guide roller when the ink ribbon is maximally wound on the unwinding core is 120 degrees or more. 4. An ink ribbon holding angle (β) of the first guide roller when the ink ribbon is wound minimum on the unwinding core is 90 degrees or less.
Ink ribbon cassette. 5. The ink ribbon cassette according to claim 1, wherein the take-up drive roller is made of a thermoplastic elastomer. 6. The material of the unwinding stop roller is any one selected from the group consisting of ABS (acrylonitrile butadiene styrene), AS (acrylonitrile styrene), PS (polystyrene), PC (polycarbonate) and POM (polyacetal). The ink ribbon cassette according to any one of claims 1 to 5, wherein: 7. The ink ribbon cassette according to claim 1, wherein an unwind stop pin or a fixing member having a guide surface for guiding the running of the ink ribbon is used instead of the unwind stop roller. .