Patent Application
20210252882
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2020-023709, filed Feb. 14, 2020, the entire contents of which are incorporated herein by reference.
Embodiments described herein relate generally to a structure for supporting a platen roller and a printer incorporating a structure for supporting a platen roller.
Conventional printers that convey a printing medium using a platen roller are designed so that the platen roller does not bend and become inoperative even when pressed by a print head. The platen roller is supported by a frame at both ends of a rotary shaft, and a bushing that assists in the sliding between the frame and the rotary shaft is interposed therebetween.
Generally, the rotary shaft has had a thickness sufficient to provide rigidity. However, in recent years, in order to reduce the weight of the printer or reduce its manufacturing cost, a shaft having a small diameter has been used as the rotary shaft. When the shaft of the platen roller has a small diameter, the rigidity lessens and may be insufficient, and the platen roller pressed by the print head may be bent.
According to one or more embodiments, a support structure for a detachable platen roller of a printer comprises a frame configured to hold the platen roller. The support structure includes a pair of bushings attached to the frame and permitting ends of a shaft of the platen roller to be inserted therein. A part of either the frame or each of the bushings located around the shaft and closer to a guide surface of the platen roller than the frame in a longitudinal direction of the platen roller forms a support part configured to receive a force applied by a print head pressing against the platen roller.
Embodiments will be described with reference to the drawings.
The printer 1 prints on a roll paper 10, and includes a housing 2, a sheet storage unit 3, and a printing unit that includes a print head 41 and a platen roller 42. The roll paper 10 is an example of a printing medium, and is, for example, a paper sheet on which a plurality of labels each having a glue layer on a back surface. The roll paper 10 is wound around a core or the like. The housing 2 includes a main body 21 and a cover 22, and houses the sheet storage unit 3, the print head 41, and the platen roller 42.
The main body 21 is, for example, a box-shaped container having an opening, and includes the sheet storage unit 3 and the like. Further, a sheet discharge port 23 is provided on a front surface of the main body 21. The sheet discharge port 23 is an opening through which the printed sheet is discharged.
The cover 22 is rotatably supported (e.g., hinged) at one end portion (hereinafter referred to as “rotation side end portion”) of the main body 21, and moves between an open position at which the main body 21 is not covered by the cover 22 opened and a close position at which the main body 21 is covered by the cover 22. The cover 22 has a flap shape configured to cover the main body 21. Further, the cover 22 is biased in a direction from the closed position toward the open position (a direction away from the main body 21) by a biasing member such as a spring.
The sheet storage unit 3 is provided in the main body 21 and covered by the cover 22. Further, the sheet storage unit 3 holds and stores the roll paper 10 so that the sheet can be pulled out by the platen roller 42.
The print head 41 and the platen roller 42 make up a printing unit provided at a position where the end portion of the cover 22 contacts the main body 21 (i.e., the end portion opposite to the rotation side end portion), and configured to print on the sheet drawn out from the sheet storage portion 3.
The print head 41 is attached to the cover 22. The platen roller 42 is provided in the main body 21. With the cover 22 in the closed position, the platen roller 42 contacts the print head 41, and the printing unit is in a printable state. More specifically, the print head 41 is attached to the cover so as to be rotatable about an axis along the width direction (i.e., X-axis direction), and is biased by an elastic member such as a spring towards the platen roller 42 when the cover 22 is in the closed position.
The print head 41 is, for example, a thermal head, and prints on a printing surface of a label by heating a thermosensitive color developing layer included in the printing surface of the label to cause the color developing layer to develop a color. The platen roller 42 sandwiches the sheet with the print head 41, rotates about the longitudinal direction to pull out the sheet from the sheet storage unit 3, and conveys the sheet.
Both ends of the platen roller 42 are rotatably supported by a frame 5 in the main body 21. The frame 5 has a pair of metal sheets along the YZ plane, other metal sheets between the pair of metal sheets and fixed to the pair of metal sheets, and the like. The frame 5 supports various components between the two opposing metal sheets and the like.
Referring back to
In addition, the bushing 6 has a pair of flat portions 67 along the longitudinal direction of the lever 62 on the outer circumferential surface thereof. The flat portion 67 has a shape in which a part of the cylindrical outer peripheral surface is removed and a flattened portion is provided. A distance between the flat portions 67 facing each other across the rotary shaft 421 is less than a diameter of the outer peripheral surface of the bushing 6.
The frame 5 has a support portion 50 (see
In a state in which the platen roller 42 is attached to the frame 5, the longitudinal direction of the lever 62 is aligned with the depth direction (i.e., the Y-axis direction) of the printer 1. In this state, the protrusion 63 fits into a recess provided in the frame 5, and the lever 62 is fixed. To remove the protrusion 63 from the recess, the claw 64 is moved in the X-axis direction. To detach the platen roller 42 from the frame 5, the lever 62 is rotated upward, and pulled upward (i.e., the Z-axis positive direction) as it is. As a result, the flat portion 67 slides on the communicating portion of the frame 5, and the bushing 6 is pulled out.
The attachment of the platen roller 42 to the frame 5 is made in the way opposite to the above-described operation. With the lever 62 facing upward, the bushing 6 is inserted downward (i.e., the Z-axis negative direction) into the communication portion (groove) of the frame 5, and the lever 62 is rotated so that the bushing 6 rotates approximately 1/4 in the support portion 50 (hole) of the frame 5. When reaching a predetermined position, the protrusion 63 fits in the recess of the frame 5.
The distance between the rib 65 and the rib 66 in the X-axis direction corresponds to a thickness of a plate material that forms the frame 5. In the state in which the bushing 6 is correctly attached to the frame 5, the edge of the support portion 50 of the frame 5 is sandwiched between the rib 65 and the rib 66. Thereby, the positions of the bushing 6 and the platen roller 42 in the X-axis direction are fixed.
Here, the bushing 6 is further provided with an auxiliary support 8. The auxiliary support 8 is provided at an end portion of the platen roller 42 closer to the guide portion 422. The auxiliary support 8 has a projection 68 that protrudes in the radial direction from the outer peripheral surface of the bushing 6. The projecting direction of the projection 68 is substantially downward in a state in which the platen roller 42 is attached to the frame 5. In this state, the projection 68 contacts a receiving surface 51 of the frame 5. The receiving surface 51 is an upward plane.
By the contact of the projection 68 to the receiving surface 51, a downward force from the print head 41 by the platen roller 42 is received, and thus, the deflection of the platen roller 42 is reduced. Further, since the receiving surface 51 is an upward plane, it is possible to stably receive the force.
Further, the contact position between the protruding portion 68 and the receiving surface 51 is preferable because the bending of the platen roller 42 due to the pressing of the print head 41 can be suppressed as the position in the X-axis direction is closer to the print head 41 and closer to the guide portion 422 of the platen roller 42.
In such a configuration, in the operation of the printer 1, the cover 22 in the open position in the state shown in
In the operable state of the printer 1, the platen roller continues to receive a force from the print head 41. However, a part of the force is received by the receiving surface 51 in contact with the projection 68. Here, in a conventional structure, the support portion 50 only supports the outer peripheral surface of the bushing 6, and there is no contact in the auxiliary support 8, so that the force is not received at this position. On the other hand, in the present embodiments, since the projection 68 and the receiving surface 51 are in contact with each other in the auxiliary support 8, deflection of the platen roller 42 can be reduced because the force to bend the platen roller 42 is reduced.
According to the embodiments described above, even if the diameter of the rotary shaft 421 of the platen roller 42 is small, it is possible to prevent the deflection of the rotary shaft 421 of the platen roller 42 due to the pressing of the print head 41.
In the above-described embodiments, the projection 68 is provided on a part of the outer circumferential surface of the bushings 6. However, the projection 68 may have a shape that surrounds the outer circumferential surface of the bushing(s) 6 by one circumference, and the deflection of the platen roller 42 may be reduced or prevented.
Next, a modified example of the above-described embodiments will be described. The same parts as those in the above-described embodiments will be denoted by the same reference numerals.
Instead of the projection 68 shown in
Further, the bushing 6 has a cutout 69. The cutout 69 is a portion in which a part of the outer circumferential surface of the bushing 6 on the guide portion 422 side is partially removed. When the platen roller 42 is mounted on the frame 5, the cutout 69 is retracted from the projection 53 and faces the projection 53. This avoids an increase in the force required to be applied during the sliding.
The auxiliary support 8 in the above-described embodiments has a protruding portion in one of the bushing 6 or the frame 5. Alternatively, both the bushing 6 and the frame 5 may have protrusions, and the protrusion portions may be in contact with each other to obtain a desired effect (e.g., reduction of the deflection of the platen roller 42).
Further, when at least one of a part of the bushing 6 in contact with the auxiliary support 8 and a part of the frame 5 is a flat surface, it is possible to stably receive the force.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-023709 | Feb 2020 | JP | national |
