Patent Grant
11772386
The present disclosure relates to a thermal transfer printer. More specifically but not exclusively, the present disclosure relates to a thermal transfer printer which improves the pressure uniformity between its printhead and a substrate to be printed upon.
Thermal transfer printers use an ink carrying ribbon. During printing, ink carried on the ribbon is transferred to a substrate which is to be printed on. To cause the transfer of ink, the printhead is brought into contact with the ribbon using, for example, an electromagnetic or pneumatic drive unit, and the ribbon is brought into contact with the substrate. The printhead contains printing elements which, when heated, whilst in contact with the ribbon, cause ink to be transferred from the ribbon and onto the substrate. Ink will be transferred from regions of the ribbon which are adjacent to printing elements which are heated. An image can be printed on a substrate by selectively heating printing elements which correspond to regions of the image which require ink to be transferred, and not heating printing elements which correspond to regions of the image which require no ink to be transferred.
Ideally, uniform pressures shall be established between each of the printing elements and the substrate to be printed on in order to ensure the print quality. However, this may be difficult to achieve in practice, because the printing elements and the surface of the substrate may be misaligned such that over-pressure or under-pressure may occur between some of the printing elements and the substrate.
It is an object of some embodiments of the present disclosure to provide a novel thermal transfer printer which obviates or mitigates at least some of the disadvantages of prior art thermal transfer printers, whether set out above or otherwise.
According to a first aspect of the present disclosure, there is provided a thermal transfer printer comprising:
In other words, the first and second structures allow the printhead carriage to rotate around the rail relative to the body of the printer, but within a limited angular range. By allowing the printhead carriage to rotate around the rail, the printhead is able to adapt its orientation with respect to the surface of the substrate, so as to ensure the printing quality. By restricting the rotation of the printhead carriage to be within a predetermined range, the printhead is prevented from rotating excessively about the rail, causing difficulty in fitting the inked ribbon. Further, the contact between the printhead and the substrate can be easily established and maintained during printing operations.
The rail may be made of metal. The printhead carriage may be made of a low friction plastic material.
The first and second structures may be configured such that, when the first structure abuts against the second structure, the rotation of the printhead carriage reaches an end point of the predetermined range.
In other words, the second structure acts as a stopper to stop the rotation of the printhead carriage from exceeding the predetermined range.
The predetermined range may be at least approximately 0.25 degree.
The printhead may comprise printing elements which are arranged in a one-dimensional linear array, and which, when heated, whilst in contact with the inked ribbon, cause ink to be transferred from the ribbon and onto the substrate.
The predetermined range may be selected such that a maximum misalignment of the array of printing elements with respect to a neutrally aligned substrate is at least 0.25 millimetres. The misalignment may represent a difference of a first linear distance between one end of the array and the substrate and a second linear difference between the other end of the array and the substrate. In an example, the maximum misalignment is approximately +/−0.55 mm.
The predetermined range may be selected such that the maximum misalignment of the array of printing elements with respect to a neutrally aligned substrate is between approximately 10% and approximately 50% of a nominal print distance between the printhead and the substrate. In an example, the maximum misalignment is approximately 27.5% of the nominal print distance.
The predetermined range may not exceed approximately 5 degrees.
The predetermined range may be approximately 2 degrees.
The predetermined range may comprise a first sub-range away from the body of the printer and a second sub-range towards the body of the printer. The first sub-range may be identical the second sub-range. The predetermined range may be +/−1 degree from a neutral position of the printhead carriage.
The first and second structures may be configured such that, a rotation of the printhead carriage relative to the body of the printer remains within a first predetermined limit in a first direction away from the body of the printer, and remains within a second predetermined limit in a second direction towards the body of the printer.
One of the first structure and the second structure may comprise a first part and a second part which are arranged such that, when the first part abuts against the other of the first structure and the second structure, the rotation of the printhead carriage reaches the first predetermined limit, and when the second part abuts against the other of the first structure and the second structure, the rotation of the printhead carriage reaches the second predetermined limit.
The other of the first structure and the second structure may be arranged between the first and second parts.
A distance between the first and second parts may be greater than a width of the other of the first structure and the second structure along a third direction that is parallel to a surface of the body of the printer.
Advantageously, the other of the first structure and the second structure is able to move (to a limited extent) between the first and second parts without abutting against the first/second part. This allows the printhead carriage to rotate relative to the body of the printer, but within a relatively small angular range.
The printhead carriage may comprise a surface facing the body of the printer, and the first structure may be coupled to the surface of the printhead carriage.
The rail may be fixedly coupled to the body of the printer. By “fixedly coupled”, it is meant that the rail cannot move relative to the body of the printer and that one or more intervening elements may be connected between the rail and the body of the printer.
The thermal transfer printer may further comprise a support plate secured to the body of the printer, wherein the support plate comprises a pair of brackets and the rail is connected between the pair of brackets.
The thermal transfer printer may further comprise a printhead carriage drive assembly configured to drive the printhead carriage so that the printhead carriage and the printhead moves linearly along the rail.
The first structure may be configured to move linearly with respect to the second structure during a linear motion of the printhead carriage along the rail.
As such, the first and second structures would not obstruct the linear motion of the printhead carriage during printing operations.
The printhead carriage may comprise a gear rack. The printhead carriage drive assembly may comprise a motor, and a circular gear which is caused to rotate by energization of the motor. The circular gear may be arranged to engage with the gear rack such that a rotation of the circular gear causes linear motion of the printhead carriage along the rail.
The rail may be located directly above a centreline of the printhead.
The thermal transfer printer may further comprise a drive housing, wherein the drive housing is configured to house the printhead carriage drive assembly, and wherein the drive housing is securable to the body of the printer.
The drive housing may be removably secured to the body of the printer. The drive housing may be securable to the body of the printer by retaining clips. The drive housing may be formed as a molded plastic part.
The tape drive may comprise a take-up spool support for supporting a spool core onto which inked ribbon can be wound to form a take-up spool. The take-up spool support may be configured to permit the spool core to rotate about a rotation axis extending substantially perpendicular from the body of the printer. The take-up spool support may extend in a fourth direction away from the body of the printer.
The tape drive may further comprise a supply spool support, the supply spool support extending in the fourth direction away from the body of the printer.
The thermal transfer printer may further comprise a user interface provided on a user interface surface of a user interface housing, wherein the user interface housing extends in the fourth direction away from the body of the printer.
The user interface surface may be substantially parallel to the body of the printer. The user interface housing may be integrally formed with the body of the printer.
The thermal transfer printer may further comprise a printhead in/out drive assembly configured to move the printhead towards and away from the substrate, the printhead in/out drive assembly being supported by the printhead carriage.
According to a second aspect of the present disclosure, there is provided a thermal transfer printer comprising:
According to a third aspect of the present disclosure, there is provided a method of operating a thermal transfer printer, the method comprising:
Rotating the printhead around the rail may comprise rotating the printhead within a limited range of permitted rotation.
The method may further comprise rotating the printhead carriage around the rail with a limited range of rotation permitted so as to align the printhead with a printing platen supporting the substrate.
The method may further comprise: moving the printhead carriage and the printhead linearly along the rail during a printing operation when the printhead is pressed against the substrate.
According to a fourth aspect of the present disclosure, there is provided a thermal transfer printer comprising:
The printhead carriage may be rotatably coupled to the body of the printer with a limited range of rotation permitted.
The rotation of the printhead carriage, the printhead and the printhead in/out drive assembly may be around a rail coupled to the body of the printer.
The printhead carriage, the printhead and the printhead in/out drive assembly may also be configured to move simultaneously in a linear fashion relative to the body of the printer.
The linear motion of the printhead carriage, the printhead and the printhead in/out drive assembly may be along the rail.
According to a fifth aspect of the present disclosure, there is provided a thermal transfer printer comprising:
According to a sixth aspect of the present disclosure, there is provided a thermal transfer printer comprising:
The drive housing may be removably secured to the body of the printer. The drive housing may be securable to the body of the printer by retaining clips.
According to a seventh aspect of the present disclosure, there is provided a thermal transfer printer comprising:
Where appropriate any of the optional features described above in relation to the first aspect of the present disclosure may be applied to other aspects of the disclosure.
It would also be understood that the terms “first”, “second”, “third” and “fourth” are simply used in the present disclosure to label the relevant elements (e.g., “structure”, “part”, “direction” etc.) for the ease of description, and do not imply any limitations to the sequence or locations of the relevant elements.
In order that the disclosure may be more fully understood, a number of embodiments of the disclosure will now be described, by way of example, with reference to the accompanying drawings, in which:
In the figures, like parts are denoted by like reference numerals.
It will be appreciated that the drawings are for illustration purposes only and are not drawn to scale.
Referring to
The terms ‘proximal’ and ‘distal’ are used within this specification. The term ‘distal’ relates to a direction pointing towards the base plate 2 and the term ‘proximal’ relates to a direction pointing away from the base plate 2.
The supply spool support 3 extends from and is rotationally fixed to the base plate 2 (e.g. cannot rotate relative to the base plate 2). In contrast, the take-up spool support 4 is rotatable relative to the base plate 2, driven by a motor (not shown). The supply spool support 3 is arranged to support a ribbon supply spool core 6, upon which is wound ink carrying ribbon 7. The supply spool core 6 and any ribbon 7 wound thereon may be referred to as a supply spool 8. While the supply spool support 3 is fixed with respect to the base, the supply spool 8 is able to rotate about the supply spool support 3 when the friction between the supply spool 8 and the supply spool support 3 is overcome. The supply spool support 3 comprises a spring 14 for retaining the ribbon supply spool 8 on the supply spool support 3. Alternatively, the supply spool support 3 may also be rotatable relative to the base plate 2, driven by, for example, another motor. In this way, the printer 1 may apply more sophisticated control of the ribbon tension between the supply spool support 3 and the take-up spool support 4.
The take-up spool support 4 is arranged to support a ribbon take-up spool core 9, upon which used ink ribbon 15 is wound following printing. The take-up spool core 9 and the used ink ribbon 15 wound thereon may be referred to as a take-up spool 10. The take-up spool support 4 comprises a retaining means (not shown) for retaining the take-up spool 10 on the take-up spool support 4. This may comprise, for example, a flat spring located on a circumferential surface of the take-up spool support 4, and which projects radially outward when relaxed, and grips an inner circumferential surface of the ribbon take-up spool core 9 when the ribbon take-up spool core 9 is installed on the take-up spool support 4. The proximal end 4a (shown in
When the motor coupled to the take-up spool support 4 causes the take-up spool support 4 to rotate in the anti-clockwise direction, the ribbon 7 is unwound from the supply spool 8, causing the supply spool 8 to rotate clockwise. The ribbon 7 travels along a ribbon path P past the printhead 5, and is wound on to the take-up spool 10. There may be one or more rollers 13 in the ribbon path P which are used to help guide the ribbon 7. One of the rollers 13a may be a sticky roller, which may have an encoder for determining ribbon speed. The motor, the take-up spool support 4, and the supply spool support 3 may be collectively referred to as a ‘tape drive’ of the printer 1.
In an embodiment, the rotation of the supply spool 8 is monitored by a sensor 62 (shown in
The printhead 5 may be any suitable printhead for use in a thermal printer. In an embodiment, the printhead 5 comprises a printhead ceramic upon which printing elements are arranged in a one-dimensional linear array (
The printhead in/out drive assembly 12 may be an electromagnetic or pneumatic drive unit. In an example, the printhead in/out drive assembly 12 may comprise an electro-permanent magnet system as described in PCT/EP2017/084503, which is hereby incorporated by reference. In an alternative example, the printhead in/out drive assembly 12 may comprise a resilient biasing member (e.g., a coil spring) and an electromagnet (e.g., a solenoid) which exert forces of opposition directions on the printhead 5.
However, it will be appreciated that the printhead in/out drive assembly 12 may take any suitable form. During activation of the in/out drive assembly 12, the ribbon 7 is also brought into contact with the substrate (not shown) to be printed on. The printing elements, when heated, whilst in contact with the ribbon 7, cause ink to be transferred from the ribbon 7 and onto the substrate to be printed on. Ink will be transferred from regions of the ribbon 7 which correspond to (i.e. are aligned with) printing elements which are heated. The array of printing elements can be used to perform printing of an image on to the substrate by selectively heating printing elements which correspond to regions of the image which require ink to be transferred, and not heating printing elements which require no ink to be transferred. Printing a single row of dots on the substrate, perpendicular to the direction of travel of the printhead 5, is sometimes referred to as a printing operation.
The operation of the printer 1 is controlled by a controller (not shown), which is provided on a printed circuit board (not shown). The printed circuit board may be mounted on the reverse side of the base plate 2. It will be appreciated that the controller may alternatively be located elsewhere and coupled to the printer 1 via a wired or wireless connection. The controller can take any suitable form, including ASICs, FPGAs, or microcontrollers which read and execute instructions stored in a memory to which the controller is connected.
The printer 1 further includes a printhead drive housing 20 (referred to as “drive housing” below), which houses a printhead carriage drive assembly 11a (shown in
The base plate 2 may define one or more generally planar surfaces from which various other components of the printer may extend. The one or more generally planar surfaces may be parallel to one another. As shown in
The base plate 2 further comprises a recessed region 19 provided adjacent to the take-up spool support 4. The recessed region 19 is recessed from the base plate plane P1 in a direction opposite to C3. The recessed region 19 is provided to enable a user to remove the used ribbon 15 safely and conveniently. For example, the recessed region 19 may be configured to permit the user to easily access an inner side of the used ribbon 15 facing the base plate 2. This allows the user to grip the inner side of the used ribbon 15, and also to grip an opposite outer side of the ribbon 15 or the spool core 9, and to easily remove the take-up spool 10.
There are generally two modes in which thermal transfer printers can be used, which are sometimes referred to as a “continuous” mode and an “intermittent” mode. In both modes of operation, the apparatus performs a regularly repeated series of printing cycles, each cycle including a printing phase during which ink is transferred to a substrate, and a further non-printing phase during which the printer is prepared for the printing phase of the next cycle.
In continuous printing, during the printing phase the printhead 5 is brought into contact with the ribbon 7, the other side of which is in contact with a substrate onto which an image is to be printed. The printhead 5 is held stationary during this process. The term “stationary” is used in the context of continuous printing to indicate that although the printhead 5 will be moved into and out of contact with the ribbon 7, it will not move relative to the ribbon path in the direction in which ribbon 7 is advanced along that path. Both the substrate and ribbon 7 are transported past the printhead 5 generally, but not necessarily, at the same speed.
In intermittent printing, a substrate is advanced past the printhead 5 in a stepwise manner such that during the printing phase of each cycle the substrate and generally but not necessarily the ribbon 7 are stationary. Relative movement between the substrate, the ribbon 7 and the printhead 5 are achieved by displacing the printhead 5 relative to the substrate and ribbon along axis C1. During each printing phase, the printhead carriage 11 moves along a length (along the axis C1) of the substrate so that the printhead 5 may print along the length of the substrate. That is, a number of printing operations are carried out while the substrate to be printed on is stationary. A total number of printing operations carried out as the printhead carriage 11 moves along the length of the substrate is sometimes referred to as a printing stroke, where carrying out a printing stroke leads to a plurality of rows of dots being printed on the substrate as the printhead carriage 11 moves along the length of the substrate. Between the printing phases of successive cycles, the substrate is advanced so as to present the next region to be printed beneath the print head 5 and the ribbon 7 is advanced so that an unused section of ribbon is located between the printhead 5 and the substrate. Accurate transport of the ribbon 7 is, therefore, necessary to ensure that unused ribbon is always located between the substrate and printhead 5 at a time that the printhead 5 is caused to conduct a printing operation.
The printer 1 is generally used in intermittent mode, but can also be used in continuous mode. Where the intermittent mode is used, the printhead carriage 11 (and the printhead 5 mounted thereon) is caused to move along a length (along the axis C1) of the substrate so as to allow its displacement along the ribbon path P.
As described above, a motor (not shown) is provided for driving the take-up spool support 4 so as to advance the ink ribbon 7 between the ribbon supply spool 8 and the ribbon take-up spool 10. The printhead carriage drive assembly 11 a uses a second, different, motor (which has an output shaft 30 shown in
With further reference to
The printhead carriage drive assembly 11 a comprises a circular gear 28. The printhead carriage 11 further comprises a gear rack 38 (also known as a linear gear rack) which engages with the circular gear 28 such that rotation of the circular gear 28 causes linear motion of the printhead carriage 11 along the rail 34. The gear rack 38 and the circular gear 28 may also be referred to as a rack and pinion arrangement. In the example shown by
As described above, the printhead 5 comprises printing elements which are arranged in a one-dimensional linear array. The one-dimensional linear array can be clearly seen in
To solve this problem, the printhead carriage 11 is able to rotate about the axis of the rail 34 so that the print force provided by the printhead in/out drive assembly 12 causes the printhead 5 to align with the misaligned substrate 16′. To prevent the printhead carriage 11 from rotating excessively about the axis of the rail 34, causing difficulty fitting ribbon 7 for example, the printhead carriage 11 comprises a first structure 40 (
As shown in the inset of
The gap 44 allows the printhead carriage 11 to rotate around the rail 34 in a clockwise direction B1 away from the base plate 2, through a limited angular range from the neutral position. When the first part 41 abuts against the upper surface of the second structure 50, the printhead carriage 11 reaches the limit of the allowable rotational range and cannot rotate further in the direction B1.
Similarly, the gap 46 allows the printhead carriage 11 to rotate around the rail 34 in an anti-clockwise direction B2 towards the base plate 2, through a limited angular range from the neutral position. When the second part 42 abuts against the lower surface of the second structure 50, the printhead carriage 11 reaches the limit of the allowable rotational range and cannot rotate further in the direction B2.
In the example of
It will be understood that by changing the widths of the gaps 44 and 46, the rotational ranges of the printhead carriage 11 in the directions B1 and B2 from the neutral positon may be easily adjusted. Further, the printer 1 may be modified such that the printhead carriage 11 is only allowed to rotate in one of the directions B1 and B2 from the neutral position. In any event, the total rotatable range of the printhead carriage 11 may be at least approximately 0.25 degree, and may not exceed approximately 5 degrees.
By providing the guide structure 36, the rail 34, the first structure 40 and the second structure 50, the printhead carriage 11 is able to adjust its orientation with respect to the surface of the substrate, so as to allow the printhead 5 mounted on the printhead carriage 11 to align with the surface of the substrate. In this way, uniform pressures can be achieved between the printing elements of the printhead 5 and the substrate, thereby improving the printing quality regardless of the surface orientation of the substrate (at least within a range). The first structure 40 and the second structure 50 further restrict the rotation of the printhead carriage 11 to be within a limited range (e.g., from about 0.25 degree to 5 degrees). Consequently, the printhead carriage 11 cannot move far away from the neutral position (as shown in
By using the rail 34 to support the printhead carriage 11, the printhead carriage 11 is able to move linearly relative to the body 2 of the printer 1 (along the rail 34) and also to tilt relative to the body 2 of the printer 1 (about the rail 34). Further, because the printhead 5 and the printhead in/out drive assembly 12 are mounted on the printhead carriage 11, the printhead 5 and the printhead in/out drive assembly 12 are also able to slide along and rotate around the rail 34 simultaneously with the printhead carriage 11. The rail 34 therefore allows two different motions of the printhead carriage 11 and the printhead 5 to take place at the same time, and greatly improves the mechanical simplicity of the printhead drive mechanism of the printer 1. In addition, the use of the rail 34 allows the printhead carriage 11 to be driven by the printhead carriage drive assembly 11 a in a reciprocating manner (along the rail 34). This is useful for the printer 1 to operate in an intermittent mode.
With reference to
With reference to
As described above, the rotation of the printhead carriage 11 around the rail 34 is restricted to be within a limited range (e.g., from about 0.25 degree to about 5 degrees). Although the rotational range of the printhead carriage 11 appears small, the linear distances moved at the end of the printhead 5 could be significant as compared to the nominal print distance of the printer 1.
The misalignment reaches its maximum value when the printhead 5 rotates to the end points of its permitted rotational range. In an example, the permitted rotational range of the printhead 5 is +/−1 degree from the neutral point. When θ1 is 1 degree, the difference of TR1 and TL1 is 0.55 mm; and when θ2 is 1 degree, the difference of TL2 and TR2 is 0.55 mm. In other words, the maximum misalignment takes up 27.5% of the nominal print distance PD.
The permitted rotational range of the printhead 5 may be selected such that a maximum misalignment of the printhead 5 with respect to the substrate 48 is at least approximately 0.25 mm. With respect to the nominal print distance, the permitted rotational range of the printhead 5 may be selected such that the maximum misalignment of the printhead 5 with respect to the substrate 48 is between approximately 10% and approximately 50% of the nominal print distance.
While a neutrally aligned substrate 48 is shown in
While
In the example illustrated by
At step S1, an inked ribbon (e.g., the inked ribbon 7) is advanced past a printhead (e.g., the printhead 5) so as to allow ink to be removed from the inked ribbon by the printhead and transferred to a substrate during a printing operation.
At step S2, the printhead is supported on a printhead carriage (e.g., the printhead carriage 11). The printhead carriage is supported by a rail (e.g., the rail 34) coupled to a body (e.g., the body 2) of the printer, and the rail extends along a direction (e.g., the axis C1) parallel to a direction of travel of the inked ribbon.
At step S3, the printhead is moved towards the substrate.
At step S4, the printhead is aligned with the substrate, by rotating the printhead around the rail. Rotating the printhead around the rail may comprise rotating the printhead within a limited range of permitted rotation
It would be appreciated that in practice, the steps may be performed in a temporal order that is different from the order of description. Further, it would be understood that the method may include additional steps. For example, the method may comprise a step of moving the printhead carriage and the printhead linearly along the rail during a printing operation when the printhead is pressed against the substrate. This step may take place during an intermittent printing mode of the printer.
The terms “having”, “containing”, “including”, “comprising” and the like are open and the terms indicate the presence of stated structures, elements or features but not preclude the presence of additional elements or features. The articles “a”, “an” and “the” are intended to include the plural as well as the singular, unless the context clearly indicates otherwise.
The term “about” or “approximately” used in the present disclosure indicate a degree of variability (e.g., 20%) in the stated numerical values.
The skilled person will understand that in the preceding description, positional terms such as ‘upper’, ‘lower’, and ‘vertical’, etc. are made with reference to conceptual illustrations of a printer, such as those showing standard sectional views and those shown in the appended drawings. These terms are used for ease of reference but are not intended to be of limiting nature. These terms are therefore to be understood as referring to a printer when in an orientation as shown in the accompanying drawings.
Although the disclosure has been described in terms of preferred embodiments as set forth above, it should be understood that these embodiments are illustrative only and that the claims are not limited to those embodiments. Those skilled in the art will be able to make modifications and alternatives in view of the disclosure which are contemplated as falling within the scope of the appended claims. Each feature disclosed or illustrated in the present specification may be incorporated in the disclosure, whether alone or in any appropriate combination with any other feature disclosed or illustrated herein.
| Number | Date | Country |
|---|---|---|
| 109562627 | Apr 2019 | CN |
| Number | Date | Country | |
|---|---|---|---|
| 20230094581 A1 | Mar 2023 | US |
