Patent Application
20250091365
Embodiments described herein relate generally to an image forming apparatus.
In the related art, known thermal printer including an anti-jam mechanism including a detection unit installed downstream of a platen roller in a paper conveyance path. According to such an anti-jam mechanism, it is possible to detect occurrence of a paper jam in the vicinity of a paper discharge position and pulling of paper by a user.
A problem to be solved by at least one embodiment of the present disclosure is to provide a technique capable of detecting an abnormality related to paper discharging with higher accuracy.
In general, according to at least one embodiment, provided is an image forming apparatus that forms an image on a sheet-shaped medium using a print head and discharges the medium through a discharge port, the apparatus including: a first detection unit (first detector) provided closer to a side of the discharge port than to the print head in a conveyance path of the medium, the first detection unit being provided on one side in a thickness direction of the medium on the conveyance path and configured to detect a bias by the medium toward the one side; and a second detection unit (second detector) provided closer to the side of the discharge port than to the print head in the conveyance path, the second detection unit being provided on the other side in the thickness direction of the medium on the conveyance path and configured to detect a bias by the medium toward the other side.
One embodiment provides a medium abnormality detection method of detecting an abnormality related to discharging of a medium in an image forming apparatus that forms an image on the sheet-shaped medium using a print head and discharges the medium through a discharge port, the method including detecting, by a processor, the abnormality related to the discharging of the medium, in which the detection of the abnormality is based on a detection result from a first detection unit provided closer to a side of the discharge port than to the print head in a conveyance path of the medium, the first detection unit being provided on one side in a thickness direction of the medium on the conveyance path and configured to detect a bias by the medium toward the one side, and a detection result from a second detection unit provided closer to the side of the discharge port than to the print head in the conveyance path, the second detection unit being provided on the other side in the thickness direction of the medium on the conveyance path and configured to detect a bias by the medium toward the other side.
Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same configuration will be denoted by the same reference numeral.
A configuration of a thermal printer according to at least one embodiment will be described.
As illustrated in
The housing 10 is formed in an approximately box shape defining an internal space, and the internal space accommodates the thermal head 21, the platen roller 22, the cutter unit 23, the upper detection unit 31, and the lower detection unit 32. The support arm 11 is a member formed to extend in one direction. Further, the support arm has one end connected to the housing 10 and the other end configured to support the roll paper R above the housing 10 so as to enable the roll paper R to be rotatable in a direction in which the paper P is unwound. Additionally, a part of the housing 10 is formed as a cover 101 covering the internal space.
A paper feed port and a paper discharge port are provided in the housing 10, and a paper conveyance path is formed in the internal space and communicated therein in a direction vertically intersecting the paper feed port and the paper discharge port. The paper P is inserted into the paper conveyance path from the paper feed port and discharged to the outside of the housing 10 from the paper discharge port. The bezel 12 is formed to allow the paper P discharged through the paper discharge port to be placed thereon, and is attached to the outside of the housing 10. The cover 101 is provided at a position where a user can easily access the paper conveyance path by removing the cover 101 from the housing 10.
The thermal head 21 and the platen roller 22 are provided upstream of the paper conveyance path, that is, provided on the paper feed port side. The upper detection unit 31 and the lower detection unit 32 are provided downstream of the paper conveyance path, that is, provided on the paper discharge port side. The cutter unit 23 is provided between the thermal head 21 and the platen roller 22, and the upper detection unit 31 and the lower detection unit 32.
The thermal head 21 has a plurality of heating elements that face one surface of the paper P in the paper conveyance path and are adjacent in the width direction of the paper P. The thermal head 21 forms an image on the paper P by allowing the plurality of heating elements to generate heat in response to input pulse waves. The platen roller 22 is configured to press, against the thermal head 21, the paper P on the paper conveyance path. The platen roller 22 conveys the paper P from the paper feed port side to the paper discharge port side on the paper conveyance path. The cutter unit 23 has a fixed blade and a movable blade. Further, the cutter unit 23 cuts the paper P printed by the thermal head 21 by moving the movable blade toward the fixed blade.
The upper detection unit 31 is provided on the upper side of the paper conveyance path in the vicinity of the paper discharge port. The upper detection unit 31 has an upper flapper 311, an upper biasing member 312, and an upper sensor 313. The upper flapper 311 is a member formed to extend in the width direction of the paper P. At least a part of the upper flapper 311 may be movably provided in the vertical direction. In the present embodiment, the upper flapper 311 is provided around an axis that is oriented in the width direction of the paper P so as to be rotatable within a predetermined rotation range. The upper biasing member 312 is a member that biases the upper flapper 311 downwards, and is configured as a compression coil spring in the present embodiment. The upper sensor 313 detects that the upper flapper 311 is moved upwards by a predetermined distance or more. The upper sensor 313 is, for example, a switch or a photoelectric sensor that detects a detected piece protruding upwards from the upper flapper 311.
The lower detection unit 32 is provided on the lower side of the paper conveyance path in the vicinity of the paper discharge port. The lower detection unit 32 has a lower flapper 321, a lower biasing member 322, and a lower sensor 323 (not illustrated). The lower flapper 321 is a member formed to extend in the width direction of the paper P. At least a part of the lower flapper 321 may be movably provided in the vertical direction. In the present embodiment, the lower flapper 321 is provided around an axis that is oriented in the width direction of the paper P so as to be rotatable within a predetermined rotation range. The lower biasing member 322 is a member that biases the lower flapper 321 upwards. In the present embodiment, the lower biasing member 322 is configured as a compression coil spring similarly to the upper biasing member 312. The lower sensor 323 detects that the lower flapper 321 is moved downwards by a predetermined distance or more. The lower sensor 323 is, for example, a switch or a photoelectric sensor that detects a detected piece protruding downwards from the lower flapper 321.
The upper detection unit 31 can detect that the paper P is biased upwards in the paper conveyance path. Similarly, the lower detection unit 32 can detect that the paper P is biased downwards in the paper conveyance path. The upper detection unit 31 and the lower detection unit 32 are respectively biased by the upper biasing member 312 and the lower biasing member 322 in the direction opposite the biasing direction of the paper P to be detected. As a biasing force of each of the upper biasing member 312 and the lower biasing member 322, more specifically, a spring load is reduced, each of the upper biasing member 312 and the lower biasing member 322 has high detection sensitivity with respect to the bias of the paper P. In the present embodiment, a vertical separation distance between the upper flapper 311 and the lower flapper 321 is set to 2 to 3 mm. Therefore, at least the upper flapper 311 is substantially configured not to contact the paper P if the normal paper P is discharged. Further, the spring load of each of the upper biasing member 312 and the lower biasing member 322 is about 0.2 N in the non-biased state and about 0.23 N in the biased state. With this degree of spring load, at the time of discharging the paper P formed to be bent to the extent that a paper jam does not occur, even if the paper P contacts the upper flapper 311, the upper flapper 311 is not sufficiently biased to cause the upper sensor 313 to detect that the upper flapper 311 is moved upwards. In the present embodiment, the upper biasing member 312 and the lower biasing member 322 have the same spring load, but may have different spring loads.
A configuration of a control system of the thermal printer will be described.
As illustrated in
The platen motor 24 rotates the platen roller 22. The cover sensor 25 detects that the cover 101 is attached to the housing 10. The communication I/F 44 communicates with a host device of the thermal printer 1. The MPU 41 cooperates with the RAM 42 to control the thermal head 21, the platen motor 24, and the cutter unit 23. Further, The MPU 41 forms an image received from the host device on the paper P, and discharges, through the paper discharge port, the paper P having the image formed thereon. Additionally, the MPU 41 cooperates with the RAM 42 to execute a paper abnormality detection process to be described later. The ROM 43 stores programs and data used for the process executed by the MPU 41.
The operation of the paper abnormality detection process according to the present embodiment will be described.
As illustrated in
If at least one of the upper detection unit 31 and the lower detection unit 32 detects the bias by the paper P (ACT 101, YES), the MPU 41 stops printing the paper P and conveying the paper P (ACT 102), and determines whether a biasing time, which is a time during which a bias is continuously maintained, is equal to or greater than a preset time threshold value (ACT 103).
If the biasing time is not equal to or greater than the time threshold value (ACT 103, NO), the MPU 41 determines whether the detected bias is released (ACT 104).
If the bias is released (ACT 104, YES), the MPU 41 resumes printing the paper P and conveying the paper P (ACT 105), and one cycle of the paper abnormality detection process ends.
In this manner, in a case where the biasing time is less than the time threshold value, after downward pulling, upward pulling, blocking, and the like occur, printing and conveyance are resumed on the assumption that the downward pulling, the upward pulling, the blocking, and the like are eliminated.
The downward pulling is a state in which a portion of the paper P, the portion being discharged through the paper discharge port, is pulled downwards by a user, as illustrated in
As illustrated in
In ACT 104, if the bias is not released (ACT 104, NO), the MPU 41 determines again whether the biasing time is equal to or greater than the time threshold value (ACT 103).
In ACT 103, if the biasing time is equal to or greater than the time threshold value (ACT 103, YES), the MPU 41 executes a jam process (ACT 106) and determines whether the bias is released (ACT 107).
In the jam process, as illustrated in
If the bias is released (ACT 107), the MPU 41 resumes printing the paper P and conveying the paper P (ACT 105), and one cycle of the paper abnormality detection process ends.
On the other hand, if the bias is not released (ACT 107, NO), the MPU 41 determines again whether at least one of the upper detection unit 31 and the lower detection unit 32 detects the bias by the paper P (ACT 101).
In ACT 101, if neither the upper detection unit 31 nor the lower detection unit 32 detects the bias by the paper P (ACT 101, NO), one cycle of the paper abnormality detection process ends.
As described above, with the thermal printer 1 of the present embodiment, it is possible to more accurately detect a paper jam, blocking, upward pulling, and downward pulling, which are abnormalities generated if the paper P is discharged. It is noted that, as illustrated in
In the above-described embodiments, the thermal printer 1 performs printing using a direct thermal recording method, but may perform printing using any other printing method. Further, in the above-described embodiments, the medium is thermal paper wound in a roll shape, but a sheet-shaped medium such as a label, a receipt, or a ticket may be used.
Additionally, in the above-described embodiments, although it is assumed that the paper conveyance path is communicated in the direction intersecting the vertical direction, the paper conveyance path may be oriented in the vertical direction or inclined with respect to the vertical direction. Further, it suffices if the upper detection unit 31 and the lower detection unit 32 are configured with two detection units that are provided so as to face each other in the thickness direction of the paper P, specifically, in the direction intersecting the conveyance direction and the width direction of the paper.
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 disclosure. 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 disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosure.
