E-RETAIL THERMAL PRINTER
FIELD OF THE INVENTION
The invention relates to a thermal printer, and more particularly to an enclosure of a thermal printer housing thermal mechanism, paper holding mechanism and cutter unit.
BACKGROUND
Conventional thermal printers comprise a thermal head which generates heat and prints on the paper, a platen having a rubber roller that feeds paper, spring which applies pressure to the thermal head causing it to contact the thermo-sensitive paper and a control board for controlling the mechanisms. Thermal printers produce an image by selectively heating coated thermal paper as the paper passes over the thermal print head wherein the coating turns black in the areas where it is heated producing the required image.
Thermal printing process requires use of heat-sensitive paper or ribbon. A roll of paper is placed in a container and fed into a slot between the printer head and the platen roller. During operation of a thermal printer an electrical current passes through heating resistor of the thermal head, which in turn generates heat in a prescribed pattern. While printing, either heat of the printer head reacts to the pigments of paper to form letters and images or on application of heat, the ink in the ribbon cartridge melts and sticks onto the paper. Due to certain advantages of Thermal printers such as faster operation, lesser noise, no requirement of ink cartridges, better performance than several traditional methods of printing etc., they have become very popular.
Need for a thermal printer has increased manifold and it is steadily penetrating our daily life because of its simplified use and improved efficiency. They have become specialized machines used for quick printing on retail stores, cashier's unit, and other special applications. They are most common in point of sale operations, information desks, supermarkets, sales outlets, ticket printing, label printing, ATM etc. for their fast printing speeds.
While thermal printers can be of varying shapes, sizes and configurations, to use such thermal printers at filing station pumps or inside a moving vehicle such as a bus for ticketing purpose etc., said printers should be portable, easy to operate and robust. Therefore, portability, operability and robustness are the primary factors which must be improved to make a thermal printer usable at places where space is not the only constraint but the operation of such thermal printers is difficult due to shorter intervals between consecutive transactions. Thermal printers existing as of date are not only bulky and heavy but also involve complex operations. Such bulky and heavy thermal printers are not useful for an operator who has to either stand or constantly keep moving during print operations. Furthermore, operations of such printers are so complex that it requires specialized skills to efficiently operate and maintain them. Operators such as a person at a gas filling station, ticketing person in a bus etc. are not considered to be skilled enough to operate and maintain such thermal printers. In fact, working with thermal printers is required to be made as simple as possible so that even an unskilled person can operate and maintain it efficiently. Such simplicity should also involve mechanism to open the printer conveniently and easily enabling an operator to diagnose the printer or to load a new paper roll.
While various advancements have been made in recent past relating to thermal head, platen, ribbon and quality of paper, there is still a need to make thermal printers more suitable for handy and easy operation. For example, at filing station pumps, where an operator needs to print sale receipts more frequently because of high arrival rate of the vehicles, the paper roll needs to be changed at a regular interval. Printers accommodating paper roll of very large diameter is one of the options to avoid changing of the paper roll at regular interval. However, at such point of sale, such printers should be small and handy and therefore cannot accommodate paper rolls having large diameters. Consequently, frequent changing of paper rolls cannot be avoided.
It is also not feasible for an operator, who is continuously printing sale receipts, to disassemble a printer frequently in order to check status of the paper roll. Availability of paper roll is of primary importance because there may be a case when the printer prints a sale receipt without paper. Such situations result in delay as the operator has to disassemble a printer to replace the paper roll and subsequently print a receipt. The time lapsed during this operation and the long queue at filing stations can cause inconvenience to the customers. Further, special care needs to
be taken in such printers as such printers utilize heat for printing and therefore availability of the paper roll in the printers during printing needs to be monitored. Although various printers have low paper sensing mechanisms, such mechanisms are inconvenient and less accurate. In case the print command is given without paper then this will reduce the life of the printer and increase chances of damaging the printer head.
Therefore, it has been observed that significant time is lost and inconvenience caused in assembly and disassembly of a printer mainly during loading of paper. Loading of paper itself consumes significant time and in such small printers no indications are provided to timely warn a user about low paper.
SUMMARY OF THE INVENTION
The present invention is contrived in consideration of these circumstance by providing a compact and portable thermal printer which can be operated and maintained conveniently and easily by any operator.
A further object of the invention is to provide a compact and handy printer enabling an operator to move conveniently with the printer and to operate said printer in an efficient manner.
Another object of the invention is to provide a mechanism to open the housing of a thermal printer that allows an operator to easily assemble and disassemble a printer housing in a very short period of time.
Yet another object of the invention is to provide compact means to support a paper roll inside a thermal printer alongwith easily operable loading and unloading means there for.
It is also an object of the invention to provide means to detect availability of a paper roll inside the printer housing and to inform the operator well in advance about status of the paper roll.
According to an embodiment, the above objects of the invention can be achieved by providing a thermal printer comprising a housing, a thermal mechanism, a paper holding mechanism and a cutter unit wherein the thermal mechanism is mounted on the base casing of the housing, cutter unit is placed pivotally in the top casing of the housing and the paper holding mechanism is disposed on the base casing of the housing.
According to another embodiment, a lever mechanism is provided for engaging and disengaging the various components of the printer, which includes a lever actuator having a lever arm, a pivoting fastener coupled to the lever arm and an actuating tab coupled to the lever arm, wherein when the lever arm is operated from the backside of the housing, it causes the actuating tab to rotate and this further causes a second actuator connected to the thermal mechanism to rotate so as to disengage the components.
According to yet another embodiment, the paper holding mechanism has a left and right paper support wherein, an optical sensor is disposed in either of the paper support at preferred distance from the edge of a paper roll mounted between the paper supports.
According to yet another embodiment, the housing comprises a button on the top casing which is linked to the second actuator by a lever mechanism which when operated causes the second actuator to disengage the components.
Preferably, either of the paper support comprises a slider, a loading lever having a loading pin connected with the slider in a relatively slidable manner, a joining portion for connecting the said paper support and the loading lever and a spring member interposed between the loading pin and a spring receiving portion formed in the paper support, the spring member urging the loading pin to return to its original position upon loading the paper roll.
According to yet another embodiment, the platen and the cutter unit is placed at fixed angle and at a fixed distance relative to the fixed mechanism. Moreover, platen and head of the thermal mechanism are locked together by the lever mechanism.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a front perspective view of a thermal printer.
Figure 2 is a cross sectional view of thermal printer illustrating lever mechanism according to the invention.
Figure 3is a cross sectional view of thermal mechanism, cutter unit and paper holding mechanism.
Figure 4 is a perspective view of paper holding mechanism with paper roll mounted.
Figure 5 is a cross sectional view of the Paper roll loading and unloading mechanism holding mechanism.
Figure 6 is a cross sectional view of a thermal printer according to an aspect of the present invention.
DETAILED DESCRIPTION
The invention may be better understood and further advantages and uses thereof more readily apparent when considered in view of the following detailed description of exemplary embodiments, taken with the accompanying drawings. These embodiments describe only a few of the various ways in which the principles of various other embodiments may be realized and the described embodiments are intended to include all such embodiments and their equivalents and the reference numerals used in the accompanying drawings correspond to the like elements throughout the description.
Referring to Figures 1 and 6, an exemplary embodiment of a thermal printer device (100) in accordance with the present invention is illustrated that includes housing (102). A thermal print
head (104), a platen (106), a cutter unit (110), lever mechanism (112) and a paper roll housing (), top casing (116) with paper cover (118) and a base casing (120) having a paper holding mechanism (122). Housing (102) also houses various other components of printer device (100) such as power supply circuit, printed circuit board, thermal logic card, FPC cables and a microcontroller or microprocessor, which are not shown in the illustration. The top casing (116) of the housing includes a slot to accommodate a button for receipt printing (124) which is in direct contact of printed circuit board disposed inside the housing. Further, a slot to accommodate a button (126) to disengage the thermal mechanism (128) from the cutter unit (110) and to disengage the thermal head (104) from the platen (106) is provided in the top casing (116). A slot for the said purpose i.e. to disengage the thermal mechanism (128) from the cutter unit (110) and to disengage the thermal head from the platen is also provided in the back plate (130) to accommodate back lever (132). Presence of print button (124) on the top casing (116) results in portability of the printer (100) and convenience to its user. A bulge (134) is present on the top casing (116), which creates space inside the paper roll housing () to accommodate a paper-roll. The housing (102) provides protection to the inner members of the thermal printer device (100).
According to an aspect, the top casing (116) is pivotally connected to one of the side walls to provide easy access to the inside of the housing (102), wherein the top casing (116) pivots through the opening position to a closing position via a hinge (136) in the side wall of the housing (102). The top casing (116) is further provided with a paper cover (118) covering an opening (140) for exiting the printed paper outside the housing (102). A rubber gasket (142) is also provided towards the top portion opposite the hinge (136) to fill the space between two mating surfaces and provide protection from moisture during rainy season and from dust particles present in the atmosphere.
Referring to figure 2 , exemplary embodiment of a lever mechanism (200) in accordance with the present invention is illustrated. The lever mechanism includes a lever arm (202) having a first end; a pivoting fastener (204) coupled to the first end of the lever arm (202); an actuating tab (206) coupled to the first end of the lever arm (202); a second actuator (208) coupled with the actuating tab (206) and a button on the top casing linked to the second actuator (208) by another
lever mechanism. When back lever (202) is operated, the actuating tab (206) rotates with the lever arm (202) which in turn causes the second actuator (208) to disengage the thermal mechanism and the cutter unit or the thermal head and the platen. Similarly, the button placed on the top casing when operated causes the second actuator (208) to disengage the thermal mechanism and cutter unit or the thermal head and the platen.
During operation, either back lever or front button may be operated to disengage thermal mechanism and cutter unit. Lever actuation is provided from backside for fixed and moving unit disengagement in thermal mechanism along with a button in the top casing for such disengagement. Back lever and front button are linked with a mechanism lever wherein the said mechanism lever releases the moving edge unit either by operating the back lever or the front button.
Referring now to Figure 3a and 3b, an exemplary embodiment of thermal mechanism (300) in accordance with the present invention is illustrated.
According to an aspect of the present invention, said thermal mechanism (300) is mounted on a base casing (120) and the cutter is placed on a top casing (116) wherein said platen (306) and cutter unit (308) are placed at fixed angle and distance relative to the fixed mechanism. During printing, a paper roll is mounted on the paper holding mechanism having the right and left paper supports and fed into a slot between the printer head and the platen roller. Thereafter, an electrical current is passed through heating resistor of the thermal head, which in turn generates heat in the required pattern. While printing, either printer head is made to react with paper pigments to form letters and images or the ink in the ribbon cartridge is melted to stick onto the paper. Thereafter, cutter unit cuts the paper from the paper roll. During printing, said cutter and thermal printing units are engaged with each other, however for opening the top casing (116) of the said housing, both units have to be disengaged from each other.
Referring now to figure 4 an exemplary embodiment of a paper holding mechanism (400) in accordance with the present invention is illustrated having a left (402) and right paper support (404) , at least one of the paper support (402, 404) having a low paper sensor assembly (406) which includes infra red emitter, phototransistor and a 4- pin connector disposed in either of the
paper supports at a preferred distance from the longitudinal edge of the paper support or at a preferred distance from the edge of a paper roll (410). Preferably, the low paper sensor assembly (406) is screwed to paper support at 20 mm roll paper diameter while the opposing paper support has a small protrusion in the form of a loading pin to receive one end of the paper roll.
According to an embodiment of the present invention, the front cover (110) is provided with a front bulge (118) to accommodate roll paper diameter of around 80mm inside the paper holding mechanism (400). The front bulge has a diameter dependent on the maximum diameter of roll paper that can be placed in the paper holding mechanism. The paper holding mechanism (400) design has two paper holders (402, 404) to maintain the paper roll (410) in a stable position wherein the paper roll is placed between the holders (402, 404) in the base casing (108) . Said paper roll (410) is placed inside a small cavity between the top casing (106) and the base casing (108) terminating in side walls of the housing (102). A paper roll (410) is placed in base casing (108) using two paper supports (402, 404) and paper loading pin , which is spring actuated. Moving unit of the thermal mechanism is blocked after loading of the print paper.
According to a preferred embodiment, in the right paper support (402) of the paper holding assembly, a low paper detecting assembly (406) is mounted to detect low paper state in the printer. The said assembly includes an optical sensor housing IR emitter, photo transistor and a 4 pin connector which is fixed to the said support with screws as mentioned herein above. However, any method known in the art for fixing an assembly with another object, such as rivets, bonding, and the like, can be used without departing from the scope of the present invention. Said assembly may be connected at 18-25 mm of the paper roll diameter, however, the low paper sensor (406) is mounted in the right paper support according to an embodiment at 20mm of the paper roll diameter. Low paper sensor (406) can detect paper roll presence within a range of 5mm. Therefore, low paper sensor is (406) placed exactly at 4mm. Once the low paper sensor goes below 20mm, light rays emitted from the IR emitter will not be reflected back to the photo transistor and it will indicate low paper as it outputs a detection signal which varies on the amount of light that is reflected back to the phototransistor.
According to yet another embodiment of the present invention, a mechanical sensor is used to open and close the circuit wherein the mechanical sensor is connected to a low paper sensor
lever and the said low paper sensor lever is in contact with the roll paper. Upto 25% of roll paper , low paper sensor will be supported by roll paper. Further, low paper sensor lever actuates the mechanical sensor by 10 degrees movement once the roll paper reaches the level of less than 25%. Accordingly, sensor will send the signal indicating low roll paper and the lever will start sliding thus actuating the sensor to close the circuit.
According to another embodiment of the invention, the roll paper preferably used is generally 80mm in diameter having an internal hole of 12mm diameter and accordingly 25% paper length of the paper is 41.4 mm. However, different roll paper of varying sizes may be used.
Referring now to Figure 5, an exemplary embodiment of a paper roll (500) loading and unloading mechanism in accordance with the present invention is illustrated. It includes a slider, a loading lever (506) having a loading pin (504) connected with the slider in a relatively slidable manner, a portion in the paper support for receiving loading pin (504), the loading lever (506) and a paper loading spring (502) interposed between the loading pin (504) and a spring receiving portion formed in the paper support, the spring member urging the loading pin (504) and the loading paper support so as to part them from each other. The loading lever (506) is operated to load and unload the paper roll on the protrusion in the paper roll support and the paper loading pin of the paper holding mechanism. When loading lever (506) is operated to load a paper roll, it slides in the slider portion of the paper support whereby spring member (502) interposed between the loading pin (504) and a spring receiving portion formed in the paper support is compressed thus moving the loading pin away from the protrusion of the paper holder. One end of the paper roll can then be inserted inside the protrusion (508) and the loading lever (506) can be released which moves the loading pin back to its original position due to the opposing force exerted by the spring to firmly hold the spring in a stable position. During the operation of paper loading mechanism the loading lever (506) of the paper loading pin is pulled manually against the force exerted by the paper loading spring (502) to load a paper roll by inserting one end of the paper roll in the protrusion of the other paper holder and then releasing the loading lever to bring the loading pin (504) to its original position to hold the paper roll in a stable position. Similarly, core of the paper roll is unloaded after paper is over.
Since other modifications and changes to fit particular requirements and environments will be apparent to those skilled in the art, the invention is not considered limited to the examples chosen for purposes of disclosure, and covers all changes and modifications which do not constitute departure from the spirit and scope of this invention.

We claim:
1. A thermal printer (100) comprising:
a housing (102);
a thermal mechanism;
a paper holding mechanism; and
a cutter unit
wherein the thermal mechanism is mounted on the base casing of the said housing (102),
said cutter unit is placed pivotally in the top casing (116) of the said housing (102) and
said paper holding mechanism is disposed on the base casing (118) of the said housing
(102).
2. The thermal printer as claimed in claim 1, wherein said housing comprises a bulge (116) on the front cover.
3. The thermal printer as claimed in claim 1, wherein said housing has a front cover attached to at least one side wall via a hinge.
4. The thermal printer as claimed in claim 1, wherein said thermal mechanism comprises a thermal head and a platen.
5. A thermal printer comprising: a thermal head;
a platen; and
a cutter unit wherein, said thermal head and said platen are locked together by a lever
mechanism.
6. The thermal printer as claimed in claim in 5, wherein the lever mechanism comprises a
lever actuator for disengaging the thermal head and said platen.
7. The thermal printer as claimed in claim in 5, wherein the a lever actuator disengages the said thermal head and the said cutter unit.
8. The thermal printer as claimed in claim 7, wherein the lever actuator comprises: a lever arm (202) having a first end and a second end;
a pivoting fastener (204) coupled to the first end of the lever arm; and
an actuating tab (206) coupled to the first end of the lever arm (202), wherein the
actuating tab (206) rotates with the lever arm (202).
9. The thermal printer as claimed in claim 8 , wherein one end of the said lever arm (202) extends outside the back plate of the said thermal printer (100).
10. The thermal printer as claimed in claim 5, comprises a button on the front casing of the said thermal printer (100) to disengage the thermal head wherein said button is linked to the second actuator (208) by a lever mechanism.
11. The thermal printer as claimed in claim 5, comprises a button on the top casing of the said thermal printer (100) to disengage the thermal head wherein, said button is linked to the second actuator (208) by a lever mechanism.
12. A thermal printer (100) comprising
a housing;
a thermal head;
a paper holding mechanism (400)
wherein said paper holding mechanism comprises of left and right paper support and a
shaft disposed between the paper supports
13. The thermal printer as claimed in claim 12, wherein either of the said support comprises
a slider;
a loading lever (506) having a loading pin (504) connected with the slider in a relatively slidable manner;
a joint portion for connecting the said paper support and the loading lever (506); and a spring member (502) interposed between the loading pin (504) and a spring receiving portion formed in the paper support, the spring member urging the loading pin (504) and the loading paper support so as to part them from each other.
14. The thermal printer as claimed in claim 12, wherein a low paper sensor (406) is disposed in any one of said paper supports.
15. The thermal printer as claimed in claim 14, wherein said low paper sensor (406) is disposed in any one of said paper supports at a preferred distance of about 3.5mm to 4.5mm from the longitudinal edge of the said paper support.
16. The thermal printer as claimed in claim 14, where the low paper sensor (406) is positioned at 4mm from the lower edge of the paper roll.