1. Field of the Invention
The present invention relates to an image generating apparatus, and more particularly, it relates to an image generating apparatus comprising a rotating arm capable of rotating a gear while rotatably (swingably) supporting the same.
2. Description of the Background Art
A drive transmission device provided with a swing member (rotating arm) capable of rotating a gear while rotatably (swingably) supporting the same is known in general, as disclosed in Japanese Patent Laying-Open Nos. 2004-225761 and 9-60705 (1997), for example.
The aforementioned Japanese Patent Laying-Open No. 2004-225761 describes a drive transmission device capable of transmitting driving force of a driving gear (drive gear) to a driven gear (take-up gear) through a swing gear (driven gear). In this drive transmission device, a swing member (rotating arm) rotatably supports the swing gear meshing with the driven gear. This swing member swings through a spring and a wire provided independently thereof. More specifically, the spring so urges the swing member that the swing gear meshes with the driving gear, while the wire so pulls the swing member that the swing gear separates from the driving gear. When the swing member is released from the pulling force of the wire, the spring urges the swing member so that the swing gear swings to mesh with the driving gear. Thus, the driving force of the driving gear is transmitted to the driven gear.
The aforementioned Japanese Patent Laying-Open No. 9-60705 describes a drive transmission device capable of transmitting driving force of a driving gear (drive gear) to a driven gear (take-up gear) through a planetary gear (driven gear), similarly to the aforementioned Japanese Patent Laying-Open No. 2004-225761. In the drive transmission device described in Japanese Patent Laying-Open No. 9-60705, a magnetizing material is added to the planetary gear while a swing member (rotating arm) rotatably supporting the planetary gear is constituted of a magnetizable material, thereby increasing frictional force between the planetary gear and the swing member. Thus, the swing member swings in the direction of rotation of the driving gear, so that the planetary gear meshes with the driving gear for transmitting the driving force of the driving gear to the driven gear.
A thermal transfer printer is generally known as an exemplary image generating apparatus comprising a rotating arm capable of rotating a gear while rotatably (swingably) supporting the same.
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A paper feed operation of the conventional thermal transfer printer is now described with reference to
In paper discharge (printing), on the other hand, the thermal transfer printer drives the motor 112 for driving the feed roller 102 and the take-up reel 108 to rotate the motor gear 112a (see
However, the conventional thermal transfer printer shown in FIGS. 16 to 21 must be provided with the helical compression spring 110c, in order to rotate the rotating arm 110b while rendering the driven gear 110a hard to rotate through resistance (frictional force) resulting from the load applied by the helical compression spring 110c in the axial direction (thrust direction). Therefore, the number of components is disadvantageously increased.
On the other hand, the drive transmission device described in the aforementioned Japanese Patent Laying-Open No. 2004-225761 must be provided with the spring and the wire independently of the swing member in order to swing the swing member, and hence the number of components is disadvantageously increased.
Further, the drive transmission device described in the aforementioned Japanese Patent Laying-Open No. 9-60705 increases the frictional force between the planetary gear and the swing member by constituting the swing member (rotating arm) of the magnetizable material while separately adding the magnetizing material to the planetary gear (driven gear). Thus, the number of components is disadvantageously increased since the magnetizing material must be separately added to the planetary gear.
The present invention has been proposed in order to solve the aforementioned problems, and an object of the present invention is to provide an image generating apparatus capable of rotating and rotatably (swingably) supporting a gear while reducing the number of components.
In order to attain the aforementioned object, an image generating apparatus according to a first aspect of the present invention comprises a normally and reversely rotatable drive gear, a driven gear meshing with the drive gear and a rotating arm of resin integrally provided with a rotation fulcrum portion rotatably mounted on the drive gear, a support shaft rotatably supporting the driven gear and a spring portion outwardly inclined by a prescribed angle with respect to the extensional direction of the support shaft.
In the image generating apparatus according to the first aspect, as hereinabove described, the rotating arm of resin is integrally provided with the spring portion outwardly inclined by the prescribed angle with respect to the extensional direction of the support shaft so that the integrally provided spring portion urges the driven gear rotatably mounted on the support shaft, thereby causing frictional force between the driven gear and the support shaft. Upon rotation of the driven gear, therefore, the rotating arm mounted with the driven gear can rotate in the direction of rotation of the drive gear due to the frictional force. Thus, the rotating arm is rotatable through the frictional force resulting from the urging force of the integrally provided spring portion, whereby no helical compression spring or the like may be separately provided for rotating the rotating arm. Consequently, the number of components can be reduced.
The aforementioned image generating apparatus according to the first aspect preferably further comprises an ink sheet for printing an image on a paper and a take-up gear for taking up the ink sheet, while the support shaft of the rotating arm is preferably formed with an arcuate outer peripheral portion at least by half on a region other than that formed with the spring portion, the rotating arm preferably rotates in the direction of rotation of the drive gear due to frictional force between the driven gear and the support shaft caused by the spring portion urging the driven gear, and the driven gear preferably meshes with or separates from the take-up gear due to rotation of the rotating arm. According to this structure, the driven gear can stably rotate about the support shaft as compared with a support shaft formed with an outer peripheral portion less than by half. Thus, the support shaft of the rotating arm can stably rotatably support the driven gear despite the spring portion integrally provided thereon.
In the aforementioned image generating apparatus according to the first aspect, the spring portion of the rotating arm is preferably integrally provided with a stop portion for inhibiting the driven gear from slipping off the support shaft. According to this structure, the stop portion integrally provided on the spring portion can inhibit the driven gear from axial slippage, whereby no E-ring is necessary for inhibiting the driven gear from axial slippage, and the support shaft of the rotating arm may not be grooved for receiving such an E-ring. Consequently, the number of components can be further reduced, and the number of assembling steps can also be reduced.
In the aforementioned image generating apparatus provided with the stop portion, the driven gear preferably further includes a receiving hole receiving the support shaft and the spring portion of the rotating arm, and the stop portion is preferably provided with a hook engaging with an edge of the driven gear after the spring portion is inserted into the receiving hole of the driven gear. According to this structure, the stop portion provided on the spring portion can easily engage with the driven gear for easily inhibiting the driven gear from axial slippage due to the engagement therebetween.
In the aforementioned image generating apparatus provided with the stop portion, the driven gear preferably further includes a receiving hole receiving the support shaft and the spring portion of the rotating arm, the spring portion preferably further includes a shaft portion arranged along the axial direction of the receiving hole of the driven gear and provided with the stop portion on an end thereof, and the axial length of the shaft portion of the spring portion is preferably substantially identical to the axial length of the receiving hole of the driven gear. According to this structure, the image generating apparatus can inhibit the driven gear from moving along the axial direction of the shaft portion of the spring portion.
In the aforementioned image generating apparatus according to the first aspect, the driven gear preferably further includes a receiving hole receiving the support shaft and the spring portion of the rotating arm, and the spring portion is preferably so provided on the rotating arm that the shaft portion of the spring portion comes into surface contact with the inner surface of the receiving hole of the driven gear and urges the inner surface of the receiving hole of the driven gear when the spring portion is inserted into the receiving hole of the driven gear. According to this structure, the spring portion can stably supply urging force to the inner surface of the receiving hole of the driven gear, thereby easily causing frictional force between the driven gear and the support shaft. Consequently, the rotating arm can easily rotate in the direction of rotation of the drive gear.
In the aforementioned image generating apparatus having the spring portion so provided on the rotating arm that the shaft portion of the spring portion comes into surface contact with the inner surface of the receiving hole of the driven gear and urges the inner surface of the receiving hole of the driven gear when the spring portion is inserted into the receiving hole of the driven gear, the spring portion is preferably rendered substantially parallel to the axial direction of the receiving hole of the driven gear when the support shaft and the spring portion of the rotating arm are inserted into the receiving hole of the driven gear. According to this structure, an axially extending portion of the outer peripheral surface of the shaft portion of the spring portion can entirely come into contact with and urge the inner surface of the receiving hole of the driven gear while the spring force is inserted into the receiving hole of the driven gear.
In this case, the support shaft and the spring portion of the rotating arm preferably have arcuate outer peripheral portions respectively, and the arcuate outer peripheral portions of the bottoms of the spring portion and the support shaft are preferably substantially arranged on the circumference of a circle. According to this structure, the arcuate outer peripheral portion of the spring portion, capable of coming into contact with the inner surface of the receiving hole of the driven gear from the bottom, can be easily substantially arranged parallelly to the axial direction of the receiving hole of the driven gear when the support shaft and the spring portion of the rotating arm are inserted into the receiving hole of the driven gear.
In the aforementioned image generating apparatus according to the first aspect, the driven gear preferably further includes a receiving hole receiving the support shaft and the spring portion of the rotating arm, and the spring portion preferably urges the inner surface of the receiving hole in a direction intersecting with the axial direction of the support shaft. According to this structure, the spring portion can easily urge the inner surface of the driven gear when the support shaft and the spring portion of the rotating arm are inserted into the receiving hole of the driven gear, thereby easily causing frictional force between the driven gear and the support shaft.
In the aforementioned image generating apparatus according to the first aspect, the support shaft of the rotating arm preferably has an arcuate outer peripheral portion, and the spring portion is preferably arranged at a prescribed interval from the arcuate outer peripheral portion of the support shaft. According to this structure, the image generating apparatus can inhibit the spring portion from coming into contact with the arcuate outer peripheral portion of the support shaft, so that the spring portion is not hard to move. Thus, the image generating apparatus can suppress reduction of the urging force of the spring portion on the driven gear.
In the aforementioned image generating apparatus according to the first aspect, the rotating arm preferably further includes a regulating portion for regulating the quantity of rotation of the rotating arm, and a reinforcing rib is preferably formed on a peripheral portion of the regulating portion of the rotating arm for suppressing deformation of the rotating arm. According to this structure, the image generating apparatus can suppress deformation of the rotating arm also when large force is applied to the regulating portion thereof.
An image generating apparatus according to a second aspect of the present invention comprises an ink sheet for printing an image on a paper, a take-up gear for taking up the ink sheet, a normally and reversely rotatable drive gear driving the take-up gear, a driven gear meshing with the drive gear and a rotating arm of resin including a rotation fulcrum portion rotatably mounted on the drive gear and a support shaft rotatably supporting the driven gear, the rotating arm is integrally provided with a spring portion outwardly inclined by a prescribed angle with respect to the extensional direction of the support shaft of the rotating arm, the driven gear further includes a receiving hole receiving the support shaft and the spring portion of the rotating arm while the spring portion is so provided on the rotating arm that the shaft portion of the spring portion comes into surface contact with the inner surface of the receiving hole of the driven gear and urges the inner surface of the receiving hole of the driven gear when the spring portion is inserted into the receiving hole of the driven gear, the spring portion of the rotating arm is integrally provided with a stop portion for inhibiting the driven gear from slipping off the support shaft while the stop portion is provided with a hook engaging with an edge of the driven gear after the spring portion is inserted into the receiving hole of the driven gear, the support shaft of the rotating arm is formed with an arcuate outer peripheral portion at least by half on a region other than that formed with the spring portion, the rotating arm rotates in the direction of rotation of the drive gear due to frictional force between the driven gear and the support shaft caused by the spring portion urging the driven gear, and the driven gear meshes with or separates from the take-up gear due to rotation of the rotating arm.
In the image generating apparatus according to the second aspect, as hereinabove described, the rotating arm of resin is integrally provided with the spring portion outwardly inclined by the prescribed angle with respect to the extensional direction of the support shaft so that the integrally provided spring portion urges the driven gear rotatably mounted on the support shaft, thereby causing frictional force between the driven gear and the support shaft. Upon rotation of the driven gear, therefore, the rotating arm mounted with the driven gear can rotate in the direction of rotation of the drive gear due to the frictional force. Thus, the rotating arm is rotatable through the frictional force resulting from the urging force of the integrally provided spring portion, whereby no helical compression spring or the like may be separately provided for rotating the rotating arm. Consequently, the number of components can be reduced. Further, the support shaft of the rotating arm is formed with the arcuate outer peripheral portion at least by half on the region other than that formed with the spring portion, whereby the driven gear can stably rotate about the support shaft as compared with a support shaft formed with an outer peripheral portion less than by half. Thus, the support shaft of the rotating arm can stably rotatably support the driven gear despite the spring portion integrally provided thereon. In addition, the spring portion of the rotating arm is so integrally provided with the stop portion for inhibiting the driven gear from slipping off the support shaft that the stop portion can inhibit the driven gear from axial slippage, whereby no E-ring is necessary for inhibiting the driven gear from axial slippage, and the support shaft of the rotating arm may not be grooved for receiving such an E-ring. Consequently, the number of components can be further reduced, and the number of assembling steps can also be reduced. Further, the driven gear further includes the receiving hole receiving the support shaft and the spring portion of the rotating arm while the stop portion is provided with the hook engaging with the edge of the driven gear after the spring portion is inserted into the receiving hole of the driven gear, whereby the stop portion provided on the spring portion can easily engage with the driven gear for easily inhibiting the driven gear from axial slippage due to the engagement therebetween. Further, the spring portion is so provided on the rotating arm that the shaft portion of the spring portion comes into surface contact with the inner surface of the receiving hole of the driven gear and urges the inner surface of the receiving hole of the driven gear when the spring portion is inserted into the receiving hole of the driven gear, whereby the spring portion can stably supply urging force to the inner surface of the receiving hole of the driven gear for easily causing frictional force between the driven gear and the support shaft. Consequently, the rotating arm can easily rotate in the direction of rotation of the drive gear.
In the aforementioned image generating apparatus according to the second aspect, the spring portion preferably further includes a shaft portion arranged along the axial direction of the receiving hole of the driven gear and provided with the stop portion on an end thereof, and the axial length of the shaft portion of the spring portion is preferably substantially identical to the axial length of the receiving hole of the driven gear. According to this structure, the image generating apparatus can inhibit the driven gear from moving along the axial direction of the shaft portion of the spring portion.
In the aforementioned image generating apparatus according to the second aspect, the spring portion is preferably rendered substantially parallel to the axial direction of the receiving hole of the driven gear when the support shaft and the spring portion of the rotating arm are inserted into the receiving hole of the driven gear. According to this structure, an axially extending portion of the outer peripheral surface of the shaft portion of the spring portion can entirely come into contact with and urge the inner surface of the receiving hole of the driven gear while the spring force is inserted into the receiving hole of the driven gear.
In this case, the spring portion preferably has an arcuate outer peripheral portion, and the arcuate outer peripheral portions of the bottoms of the spring portion and the support shaft are preferably substantially arranged on the circumference of a circle. According to this structure, the arcuate outer peripheral portion of the spring portion, capable of coming into contact with the inner surface of the receiving hole of the driven gear from the bottom, can be easily substantially arranged parallelly to the axial direction of the receiving hole of the driven gear when the support shaft and the spring portion of the rotating arm are inserted into the receiving hole of the driven gear.
In the aforementioned image generating apparatus according to the second aspect, the spring portion preferably urges the inner surface of the receiving hole in a direction intersecting with the axial direction of the support shaft. According to this structure, the spring portion can easily urge the inner surface of the driven gear when the support shaft and the spring portion of the rotating arm are inserted into the receiving hole of the driven gear, thereby easily causing frictional force between the driven gear and the support shaft.
In the aforementioned image generating apparatus according to the second aspect, the spring portion is preferably arranged at a prescribed interval from the arcuate outer peripheral portion of the support shaft. According to this structure, the image generating apparatus can inhibit the spring portion from coming into contact with the arcuate outer peripheral portion of the support shaft, so that the spring portion is not hard to move. Thus, the image generating apparatus can suppress reduction of the urging force of the spring portion on the driven gear.
In the aforementioned image generating apparatus according to the second aspect, the rotating arm preferably further includes a regulating portion for regulating the quantity of rotation of the rotating arm, and a reinforcing rib is preferably formed on a peripheral portion of the regulating portion of the rotating arm for suppressing deformation of the rotating arm. According to this structure, the image generating apparatus can suppress deformation of the rotating arm also when large force is applied to the regulating portion thereof.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
An embodiment of the present invention is now described with reference to the drawings.
The structure of a thermal transfer printer according to the embodiment of the present invention is described with reference to FIGS. 1 to 15. According to this embodiment, the present invention is applied to the thermal transfer printer, which is an exemplary image generating apparatus.
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According to this embodiment, the support shaft 10f of the rotating arm 10b has an arcuate outer peripheral portion of about 300° as viewed from the axial direction of the support shaft 10f, as shown in
According to this embodiment, the spring portion 10g is substantially parallel to the axial direction of the receiving hole 10e of the swing gear 10a when the swing gear 10a of the rotating arm 10b is fitted with the support shaft 10f and the spring portion 10g, as shown in
According to this embodiment, the axial length of the shaft portion 10k of the spring portion 10g is substantially identical to that of the receiving hole 10e of the swing gear 10a.
According to this embodiment, the shaft portion 10k of the spring portion 10g has an arcuate outer peripheral portion as viewed from the axial direction of the support shaft 10f, as shown in
According to this embodiment, a hook 10m (see
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A paper feed operation of the thermal transfer printer is now described with reference to
In paper discharge (printing), on the other hand, the thermal transfer printer drives the motor 12 for driving the feed roller 2 and the take-up reel 8 to rotate the motor gear 12a (see
The motor 13 for driving the print head 7 rotates the print head 7 in a direction (along arrow L1 in
According to this embodiment, as hereinabove described, the spring portion 10g outwardly inclined by the prescribed angle with respect to the extensional direction of the support shaft 10f is so integrally provided on the rotating arm 10b of resin that the integrally provided spring portion 10g urges the swing gear 10a thereby causing frictional force between the swing gear 10a and the support shaft 10f when the swing gear 10a is rotatably mounted on the support shaft 10f. Upon rotation of the swing gear 10a, therefore, the rotating arm 10b mounted with the swing gear 10a can rotate in the direction of rotation of the feed roller gear 9 due to the frictional force. Thus, the rotating arm 10b is rotatable through the frictional force resulting from the urging force of the integrally provided spring portion 10g, whereby no helical compression spring or the like may be separately provided for rotating the rotating arm 10b. Consequently, the number of components can be reduced.
According to this embodiment, the support shaft 10f of the rotating arm 10b is formed with the arcuate outer peripheral portion at least by half on the region other than that formed with the spring portion 10g, whereby the swing gear 10a can stably rotate about the support shaft 10f as compared with a support shaft formed with an outer peripheral portion less than by half. Thus, the support shaft 10f of the rotating arm 10b can stably rotatably support the swing gear 10a despite the spring portion 10g integrally provided thereon.
According to this embodiment, the spring portion 10g of the rotating arm 10b is so integrally provided with the stop portion 101 for inhibiting the swing gear 10a from slipping off the support shaft 10f that the stop portion 101 can inhibit the swing gear 10a from axial slippage, whereby no E-ring is necessary for inhibiting the swing gear 10a from axial slippage, and the support shaft 10f of the rotating arm 10b may not be grooved for receiving such an E-ring. Consequently, the number of components can be further reduced, and the number of assembling steps can also be reduced.
According to this embodiment, the swing gear 10a is provided with the receiving hole 10e receiving the support shaft 10f and the spring portion 10g of the rotating arm 10b while the stop portion 101 is provided with the hook 10m engaging with the edge 10b of the swing gear 10a after the spring portion 10g is inserted into the receiving hole 10e of the swing gear 10a, whereby the stop portion 101 provided on the spring portion 10g can easily engage with the swing gear 10a for easily inhibiting the swing gear 10a from axial slippage due to the engagement between the swing gear 10a and the stop portion 101.
According to this embodiment, the spring portion 10g is so provided on the rotating arm 10b that the shaft portion 10k of the spring portion 10g comes into surface contact with the inner surface of the receiving hole 10e of the swing gear 10a and urges the inner surface of the receiving hole 10e of the swing gear 10a when the spring portion 10g is inserted into the receiving hole 10e of the swing gear 10a, whereby the spring portion 10g can stably supply urging force to the inner surface of the receiving hole 10e of the swing gear 10a, for easily causing frictional force between the swing gear 10a and the support shaft 10f. Consequently, the rotating arm 10b can easily rotate in the direction of rotation of the feed roller gear 9.
According to this embodiment, the axial length of the shaft portion 10k of the spring portion 10g is rendered substantially identical to that of the receiving hole 10e of the swing gear 10a, so that the thermal transfer printer can inhibit the swing gear 10a from moving along the axial direction of the shaft portion 10k of the spring portion 10g.
According to this embodiment, the arcuate outer peripheral portions of the bottoms of the spring portion 10g and the support shaft 10f are substantially arranged on the circumference of the circle O1, whereby the arcuate outer peripheral portion of the spring portion 10g, capable of coming into contact with the inner surface of the receiving hole 10e of the swing gear 10a from the bottom, can be easily substantially arranged parallelly to the axial direction of the receiving hole 10e of the swing gear 10e when the support shaft 10f and the spring portion 10g of the rotating arm 10b are inserted into the receiving hole 10e of the swing gear 10a.
According to this embodiment, the spring portion 10g is arranged at the prescribed interval from the arcuate outer peripheral portion of the support shaft 10f, whereby the thermal transfer printer can inhibit the spring portion 10g from coming into contact with the arcuate outer peripheral portion of the support shaft 10f, so that the spring portion 10g is not hard to move. Thus, the thermal transfer printer can suppress reduction of the urging force of the spring portion 10g on the swing gear 10a.
According to this embodiment, the reinforcing rib 10j is formed on the peripheral portion of the boss 10h of the rotating arm 10b for suppressing deformation of the rotating arm 10b, whereby the thermal transfer printer can suppress deformation of the rotating arm 10b also when large force is applied to the boss 10h thereof.
Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.
For example, while the above embodiment has been described with reference to the thermal transfer printer employed as an exemplary image generating apparatus, the present invention is not restricted to this but is also applicable to an image generating apparatus other than the thermal transfer printer, so far as the apparatus comprises a structure capable of rotating a gear while rotatably (swingably) supporting the same.
While the support shaft provided on the rotating arm is formed with the arcuate outer peripheral portion of about 300° on the region other than that formed with the spring portion in the aforementioned embodiment, the present invention is not restricted to this but the support shaft provided on the rotating arm may simply be formed with an arcuate outer peripheral portion at least by half (180°).
While the spring portion is integrally provided with the stop portion for inhibiting the feed roller gear from slipping off the support shaft in the aforementioned embodiment, the present invention is not restricted to this but the stop portion may alternatively be provided on a member other than the spring member. For example, the stop portion may be integrally provided on the support shaft. Further alternatively, a separately formed stop member may be employed for inhibiting the feed roller gear from slipping off the support shaft.
While the spring portion is so provided on the rotating arm that the shaft portion thereof comes into surface contact with and urges the inner surface of the receiving hole of the swing gear when the spring portion is inserted into the receiving hole of the swing gear in the aforementioned embodiment, the present invention is not restricted to this but the spring portion may alternatively be provided on the rotating arm so that the shaft portion thereof comes into line or point contact with and urges the inner surface of the receiving hole of the swing gear.
While the rotating arm is provided with the single spring portion in the aforementioned embodiment, the present invention is not restricted to this but the rotating arm may alternatively be provided with two spring portions, as shown in
Number | Date | Country | Kind |
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2005-239554 | Aug 2005 | JP | national |