Patent Application
20090152795
1. Field of the Invention
This invention relates generally to a sensor mechanism and, more particularly, to a compact low paper sensor mechanism.
2. Description of the Background
Presently, there are several different types of printers available. However, all printers share common components, such as a print head, a platen, a paper supply and a control mechanism. The control mechanism controls a motion of the print head relative to the paper supply, selects a character to be printed, and advances and retracts the paper supply, as necessary.
However, regardless of the type of printer used, it is generally undesirable to operate a printer without paper. For example, ink-based printers that are operated without paper will transfer ink into the platen, which may, in turn, stain a back side of subsequent sheets of paper and may also damage print writes within the print head.
Also, thermal printers that are operated without paper may overheat, since the paper is also used to absorb heat generated by the print head during printing operations. In addition, operating thermal printers without paper may cause excessive wear to the print head, since the print head would be running directly on the platen, instead of on the paper.
Therefore, in order to avoid operating the printers without paper, conventional printers have been provided with low-paper sensing and warning systems. Moreover, low-paper sensing has recently become an important requirement, as retailers move towards system management, which requires system notification that a paper supply is near completion.
However, previously developed low-paper sensors have poor accuracy. That is, since these low-paper sensors typically consist of a lever that rubs on one side edge of a paper supply roll, the lever either drops over the top of the paper supply roll or into a core of the paper supply roll due to a movement (e.g., bouncing or jumping) of the paper supply roll during an operation of the printer; thereby causing the lever to erroneously trip a switch to indicate that the paper supply is low.
Therefore, in order to address the poor accuracy of these low-paper sensors, printers have been provided with a sensing mechanism that includes an optical sensor and two support rollers, which support a paper supply roll. The two support rollers are spaced apart from each other at a predetermined distance, so that when a diameter of the paper supply roll becomes less than the predetermined distance, the paper supply roll drops between the two rollers and is then detected by the optical sensor. However, printers with such a sensing mechanism require an additional amount of space in order to accommodate for the paper supply roll which is allowed to drop between the two rollers, which, in turn, increases a size and a manufacturing cost of the printer.
Thus, what is needed is a sensor mechanism capable of accurately detecting a low paper condition while minimizing a required space within a printer.
The shortcomings of the prior art are overcome and additional advantages are provided by a low paper sensor mechanism for a printer including first and second support rollers rotatable about a first and second rotational axis, respectively, and attached within the printer to support a paper supply roll, the first and second support rollers spaced apart from each other at a predetermined distance, the first and second support rollers and rotational axes configured to translate in a path between a first position and a second position, first and second biasing members corresponding to the first and second support rollers, respectively, the first and second biasing members biasing the first and second support rollers toward the second position, the path between the first and second positions being collinear with a translational axis of the first and second biasing members, respectively and a detection device, including a light emitting element and a light detecting element, disposed adjacent to the first and second support rollers, the light emitting element being disposed in a line of sight of the light detecting element, wherein the first and second support rollers move from the first position to the second position when a diameter of the paper supply roll is less than or equal to the predetermined distance between the first and second support rollers and the paper supply roll disrupts the line of sight between the light emitting element and the light detecting element.
Additional features and advantages are realized through the techniques of the present invention. Other embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed invention. For a better understanding of the invention with advantages and features, refer to the description and to the drawings.
The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
The detailed description explains the preferred embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.
The present invention will be described with respect to a point-of-sale (“POS”) printer having a paper supply roll. However, the present invention is also applicable to other devices including any other type of material disposed on a roll, wherein a dimension (e.g., a diameter) of the material supply roll decreases during an operation of the device.
Referring to
As illustrated in
In exemplary embodiments, the first and second support rollers 104 and 106 are rotatably mounted within the housing 20 adjacent to and in contact with a surface of the paper supply roll 102. The first and second support rollers 104 and 106 are rotatable about a first and second rotational axes 123 and 125, respectively. That is, the first and second support rollers 104 and 106 are configured such that the paper supply roll 102 is capable of freely rotating in order to feed the paper sheet 116 from the paper supply roll 102. As illustrated in
In exemplary embodiments, the housing 20 further includes first and second support roller guide members 120 and 122, which guide a movement of the first and second support rollers 104 and 106, respectively. That is, in exemplary embodiments, the first and second support roller guide members 120 and 122 include a slot which defines a path in which the first and second rotational axes 123 and 125 of the first and second support rollers 104 and 106, respectively, are allowed to travel. In further exemplary embodiments, the first and second support roller guide members 120 and 122 extend substantially in parallel with each other. As illustrated in
In exemplary embodiments, the first and second support rollers 104 and 106 include support members 132 which are disposed on opposite ends of the first and second support rollers 104 and 106. That is, in exemplary embodiments, the support members 132 are configured to travel within the cavity 130 defined by the first and second support guide members 120 and 122.
In exemplary embodiments, the compact low-paper sensor mechanism 100 further includes first and second biasing members 108 and 110 which correspond to the first and second support rollers 104 and 106, respectively. The first and second biasing members 108 and 110 provide a force onto the first and second support rollers 104 and 106 along a translational axis 111, such that the first and second support rollers 104 and 106 are biased toward the second position. In exemplary embodiments, the path 127 between the first and second position is collinear with the translational axis 111 of the first and second biasing members 108 and 110, respectively.
In exemplary embodiments, the paper supply roll 102 is held in place by gravity, such that the surface of the paper supply roll 102 is maintained in contact with the first and second support rollers 104 and 106 while the paper sheet 116 is drawn from the paper supply roll 102.
As illustrated in
However, during an operation of the printer 10, a diameter (e.g., the first diameter D1) of the paper supply roll 102 reduces to a different diameter (e.g., the second diameter D2), since the paper sheets 116 are removed from the paper supply roll 102. The mass of the paper supply roll 102 is thereby reduced, which, in turn, reduces the force created by gravity and the paper supply roll 102. Therefore, as illustrated in
Referring now to
In the current exemplary embodiment, the detection device 112 is disposed within the housing 20, such that when the diameter of paper supply roll 102 (e.g., the second diameter D2) is less than or equal to the predetermined distance L between the first and second support rollers 104 and 106, the paper supply roll 102 drops between the first and second support rollers 104 and 106 in a direction opposite to a direction defined by the first and second support rollers 104 and 106 moving toward the second end 128 (e.g., the second position) of the first and second support guide members 120 and 122 from the first position, to thereby disrupt the line-of-sight 138 of the detection device 112. That is, the paper supply roll 102 translates along an axis that corresponds to direction arrow 141 in phantom and is parallel to axis 111, as depicted in
While the preferred embodiments to the invention have been described, it will be understood that those skilled in the art, both now and in the future, may make various improvements and enhancements which fall within the scope of the claims which follow. These claims should be construed to maintain the proper protection for the invention first described.
