GB2583976A

GB2583976A - Drinking mug image transfer heater mat and method of using one

Info

Publication number: GB2583976A
Application number: GB1907003.6A
Authority: GB
Inventors: Cullen David
Original assignee: Pce Automation Ltd
Current assignee: Pce Automation Ltd
Priority date: 2019-05-17
Filing date: 2019-05-17
Publication date: 2020-11-18
Anticipated expiration: 2039-05-17
Also published as: GB201907003D0; GB2583976B

Abstract

Drinking mug image transfer heater mat 2 including a heated region 28 including a first zone 30 and a second zone 32 and at least one resistance heating element 12, 34, 36 for heating the first and second zones. At least one of the resistance heating elements is configured to supply a first energy output per unit area of the heated region in the first zone and a second higher energy output per unit area of the heated region in the second zone. The second higher energy output per unit area is preferably at last 20% higher than the first energy output. The at least one resistance heating element may comprise only one continuous heating element. The at least one resistance heating element may comprise a heating filament having a first cross-sectioned area or first overall length per unit area in the first zone and a heating filament having a second smaller cross-sectioned area or second higher overall length per unit area in the second zone. A method of printing an image on a mug is also disclosed.

Description

DRINKING MUG

IMAGE TRANSFER HEATER MAT AND METHOD OF USING ONE

[0001] The present invention relates to heater mats used for transferring images onto drinking mugs and more particularly onto ceramic drinking mugs and a method of using one.

[0002] In the past a process referred to as the silicone wrap process has been used for transferring images onto ceramic mugs. The process involves providing a reverse image on thermal transfer paper which is wrapped around a mug and held in place using adhesive tape. A silicone band is then wrapped around the mug and thermal transfer paper and the wrapped mug is then conveyed through a heat tunnel where the image is transferred onto the mug by a sublimation process. When the mug emerges from the heat tunnel it is cooled and the wrapping is removed. This technique provides reasonably good image transfer but is labour intensive, slow and difficult to automate. An alternative method is one which involves the use of a heater mat which is clamped around a mug around which thermal transfer paper bearing an image has been placed. The heater mat has electrical heater wires incorporated into it and has a PTFE (polytetrafluoroethylene) lining provided to reduce the tendency of the thermal transfer paper to stick to the heater mat. Existing heater mats suffer from a number of disadvantages. In regions of the mug which are thick or adjacent to thick regions the thick ceramic material acts as a heat sink and inadequate heating occurs which in turn reduces the efficiency of the sublimation or printing process in which ink is transferred from the thermal transfer paper to the mug. This effect is particularly noticeable adjacent to the handle and the base of a mug. Conversely, in other regions of the mug, the -2 -temperature is often too high which results in so-called bleeding or mixing of the different colours of ink transferred to the mug. Still further disadvantages are attributable to the PTFE lining. Firstly the PTFE lining has a limited life and often breaks up after around 500 print cycles. Secondly the PTFE laver impedes the transfer of heat from the heater mat to the mug.

[0003] An object of the invention is to overcome at least some of the above mentioned disadvantages [0004] According to a first aspect of the invention there is provided a drinking mug image transfer heater mat including a heated region including a first zone and a second zone and at least one resistance heating element for heating the first and second zones wherein the at least one resistance heating element is configured to supply a first energy output per unit area of the heated region in the first zone and a second higher energy output per unit area of the heated region in the second zone. The provision of two such zones permits the delivery of heat to the mug to be tailored so as to provide a higher energy output per unit area in regions where the mug ceramic is thick or adjacent heat sink regions such as those close to the base and handle, in order to ensure that these regions reach the required temperature so that effective image transfer in these regions takes place and so-called image fade is avoided. The delivery of heat can also be tailored so as to ensure that regions remote from such heat sink regions do not become overheated and thereby become subject to colour bleeding.

[0005] Preferably the second energy output is at least 20% higher than the first energy output. Such a difference in energy outputs has been found to have a significant effect on -3 -the image fade and bleeding problems referred to above. More preferably the second energy output is at least 30% higher and even more preferably around 35% higher than the first energy output. Such a difference in energy outputs has been found to provide optimisation of image transfer for a mug of typical thicknesses. For certain applications the second energy output may be around 50% higher than the first energy output.

[0006] Preferably the at least one resistance heating element comprises only one continuous heating element. Such an arrangement means that only one source of electrical energy needs to be connected to the heater mat in order to heat it. Furthermore this arrangement simplifies the design and manufacture of the heater mat.

[0007] Preferably the at least one heating element comprises a heating filament having a first cross-sectioned area in the first zone and a heating filament having a second smaller cross-sectional area in the second zone. Such an arrangement allows a total filament length per unit area of the heater's mat to be constant throughout the entirety of the heated region.

[0008] Alternatively the at least one heating element includes a first heating filament disposed at a first overall filament length per unit area in the first zone and a second heater filament disposed at a second higher overall filament length per unit area in the second zone. Such an alternative arrangement allows the cross-sectional areas of the heating filaments in the first and second zones to be the same, which may be advantageous for certain manufacturing techniques for example if the heating filaments are wire heating filaments. -4 -

[0009] The at least one heating element may be entirely constituted by filament material having a substantially uniform cross-sectional area, such as wire filament material or etched foil filament material.

[0010] Preferably the at least one heating element comprises at least one foil heating element. Foil heating elements spread the heat output delivered by the heating element relative to wire heating elements. Due to the manner in which foil heating elements are usually formed they provide a high degree of design flexibility.

[0011] Preferably the at least one heating element comprises at least one etched foil heating element such as a chemically etched foil heating element. Forming heating element/s by an etched foil technique makes it easy to tailor the resistivity of a particular portion of the heating element which can be used to alter the heat output of a portion of the heated region of the heater mat occupied by that particular portion of the heating element.

[0012] Preferably the heater mat includes an inwardly facing heating element layer including the at least one heating element in a medium including glass fibre reinforcement. It has been found that the glass fibre reinforcement reduces the tendency for the heating element layer to stick to surfaces that it comes into contact with, such as the thermal transfer paper, and permits the heater mat to be used for approximately 3000 print cycles as opposed to around 500 print cycles for a conventional heater mat with a PTFE layer covering its innermost surface. Furthermore, obviating the need for a PTFE layer increases the rate of heat transfer from the heater mat to the thermal transfer paper/mug. -5 -

[0013] Preferably the heater mat includes a heating element layer including the at least one heating element and an insulation layer. The insulation layer may advantageously comprise silicone foam material and preferably comprises closed cell silicone foam material. Such an insulation layer speeds up the printing process and facilitates handling of the heater mat and mug when heated.

[0014] Preferably in a perimeter region of the mat a spacer is provided between the heating element layer and the insulation layer to space these layers further from each other than in a central region of the mat. When a heater mat with such a configuration is urged inwardly around a mug, inner surfaces of such perimeter regions will be urged inwardly towards the mug with a greater force than other regions of the heater mat, thereby providing improved heat transfer between the heater mat and the mug in these regions.

[0015] Preferably the heater mat has a substantially quadrilateral perimeter having four sides, the heated region extends to adjacent all four sides thereof and the first zone of the heated region only borders at least a majority of one of the sides but does not border any of the other sides. With such a configuration, when the heater mat is wrapped around a mug, the three sides, along which the second zone extends, can be positioned adjacent to and on opposite side of the handle and adjacent to the base. These are areas where ceramic material constitutes a significant heat sink and where the provision of additional heating energy assists in providing uniform heating of the mug.

[0016] Preferably at a boundary region between the first zone and the second zone portions of the heating element of the first zone are interdigitated with portions of the -6 -heating element of the second zone. With such an arrangement the heater mat will not provide an abrupt change of energy output at a junction between the first and second zones. Instead, a gradual change of energy output will be provided between the first and second zones in this boundary region.

[0017] According to a second aspect of the invention there is provided a method of transferring an image onto a drinking mug including: providing an image on an image transfer membrane; providing an image transfer heater mat including at least one resistance heating element and a heated region including a first zone configured to supply a first energy output per unit area of the heated region and a second zone configured to supply a second higher energy output per unit area of the heated region; urging the heater mat towards the drinking mug with the image transfer membrane positioned between the heater mat and the drinking mug; and heating the heater mat by means of the at least one resistance heating element.

[0018] The invention will now be described by way of example only with reference to the accompanying drawings.

[0019] Fig. 1 -shows a perspective view of the heater mat according to the invention loosely placed around an inverted mug.

[0020] Fig. 2 -shows a schematic laid-flat view of the heating element of the heater mat which is embedded in a heater mat according to a first embodiment of the invention.

[0021] Fig. 3 -shows further schematic views of the heating element of the first embodiment of the invention.

[0022] Fig. 4 -shows a schematic view similar to Fig. 3 of a second alternative heating element arrangement of a second embodiment of the invention.

[0023] Figs. 5 to 12 -shows various steps in the process for manufacturing the heater mat according to the invention.

[0024] Fig. 13 shows schematically the components including the heater mat according to the first aspect of the invention used to perform the method according to the second aspect of the invention.

[0025] Fig. 14 -shows the components shown in Fig. 13 assembled around a mug for performing the method according to the second aspect of the invention.

[0026] The heater mat 2 according to the invention is shown in Fig. 1 loosely placed around an inverted ceramic drinking mug 4. The mat 2 has a substantially cylindrical shape with a longitudinal gap 6 which allows the mat to spring open to the shape shown in Fig. 1 or be clamped around a cylindrical mug as shown in Fig. 14. The mat includes an inner heating element layer 8 and an outer insulation layer 10. The outer insulation layer 10 preferably comprises silicone closed-cell high temperature sponge or foam material. Materials other than silicone may be employed. The sponge or foam may not be of the closed-cell type. The foam or sponge may not be high temperature foam or sponge if the heater mat can be used at relatively low temperatures. A heating element 12 in the heating element layer 8 terminates adjacent a first side 14 of the heater mat 2 at a terminal tab 22 with a pair of contact pads 24 shown in Fig.2. A power cable 38 connects a plug 40 to the contact pads 24. -8 -

[0027] Fig. 2 shows a schematic cross-sectional view through the thickness of the heating element layer 8 of a first embodiment of the invention which has been shown laid flat for ease of illustration and explanation. In its laid-flat configuration the heater mat 2 has a substantially quadrilateral perimeter with first 14, second 16, third 16 and fourth 20 sides. The heating element layer 8 includes an outer layer 26 of silicone reinforced with two-ply woven glass fibre and a similar inner layer 27 which is not shown in Fig. 2 in order that the heating element 12 of the heating element layer 6 is clearly visible. Reinforcement other than glass fibre could be used, such as carbon fibre or other suitable reinforcing materials. Silicone is an advantageous material to use for the outer layer 26 and the inner layer 27 of the heating element layer due to its low specific heat capacity, high electrical resistance, high strength and high moisture resistance.

[0026] The heating element 12 is an etched heating element. The heating element is preferably a chemically etched foil heating element. Etched foil heating elements provide rapid heat-up, precise temperature control and relatively wide heater tracks leading to more evenly distributed heating. A suitable material for the heating element is stainless-steel however other materials such as copper and copper alloy could be used. The heating element 12 could alternatively be a wire or some other form of heating element. The heating element is constituted by a single continuous heating element which extends between the contact pads 24. The heating element could however be constituted by more than one heating element each of which is terminated with contact pads. The heating element 12 defines a heated region 28 of the heater mat 2 which preferably extends outwardly to close to all sides of the heater mat. The heated region 28 comprises a -9 -first zone 30 and a second zone 32. The limits of the first and second zones are shown with dashed lines in Figs. 3 and 4. The heating element 12 comprises a first heating filament 34 in the first zone 30 and a second heating filament 36, in two parts, in the second zone 32. In Fig. 2 the first heating filament 34 is depicted with a dark line and the second heating filament 36 is depicted with a lighter coloured line. Both of the heating filaments 34 and 36 are serpentive or sinuous heating filaments. The first and second heating filaments are connected to each other so as to form a single continuous heating element 12. While the heating filaments are shown schematically in Fig. 2 as having the same widths, the second heating filament 36 is narrower in width than the first heating filament 34 as can be seen in Fig. 3 which includes expanded views A and B which respectively show details of the second 36 and first 34 heating filaments. Both Figs. 3 and 4 and the associated expanded views A, B, C and D thereof are schematic and dimensions have been adjusted to emphasise certain characteristics of the first and second heating filaments.

[0029] Fig. 3 (first embodiment) shows a first version of the heating element layer 8 in which the distances d1 between the centres of adjacent lengths of the heating filaments is substantially constant throughout the heated region (as shown in Fig. 2). The difference between the first and second heating filaments is that the first heating filament 34 in the first zone 30 has a substantially uniform width W1 and the second heating filament 36 in the second zone 32 has a narrower substantially uniform width W2. Since the power emitted by an electrical heating element is inversely proportional to the cross-sectional area of the heating element, for both alternating current and direct current applications, for heating elements of uniform thickness (i.e. -10 -the dimension perpendicular to a major surface of the mat), which would generally be the case for etched foil heating elements, the power emitted by the heating filaments 34 and 36 will be inversely proportional to their widths. For a heating filament subjected to direct current the power output P is: P = I2R... (1) where I is the current and R is the resistance. Since the resistance R of a heating element is: R = pL... (2) A where p is the specific resistivity of the heating element material, L is the length of the heating element and A is the cross-sectional area of the heating element. The cross-sectional area A is: A = t W... (3) where t is the heating element thickness and W is the heating element width. From (1), (2) and (3) it can be deduced that for a given area of one of the zones including an overall length L of heating element: P = I2pL... (4) tW If the power output per unit area in the first and second zones is P1 and P2 respectively and the width of the heating elements therein are WI and W2 respectively then from (4): = I2pL... (5) tWi P2 = I2pL... (6) tW2 If the heat output per unit area in the second zone 32 is 35% higher than the heat output per unit area in the first zone 30 then: P2 = 1.35 pi... (7) From (5), (6) and (7): -= 1.35 Accordingly: 1.35 LE ttç thus: [VI Since for heating elements subject to alternating current power output is also inversely proportional to cross-sectional area, the same relationship between power output and filament width applies. Using formula (9) the relative widths of the heating filaments in the first zone 30 and the second zone 32 can be selected to provide the required ratio -12 -of power outputs delivered by those zones of the heater mat 2.

[0030] An alternative configuration of heating filaments in an alternative heating element layer 8a which would provide different power outputs in the first and second zones is shown schematically in Fig. 4 (second embodiment). In the configuration shown in Fig. 4, a first zone 30a contains a first heating filament 34a and a second zone 32a contains a second heating filament 36a. The first heating filament 34a and the second heating filament 36a both have the same thickness (i.e. the dimension perpendicular to the major surface of the mat) and the same width W. The differential energy outputs between the first zone 30a and the second zone 32a is provided by the distance between adjacent lengths of the heating filaments in the first and second zones. This distance is d3 in the first zone 30a and a smaller distance d2 in the second zone 32a. If the energy output per unit area of the second zone 32a is to be 35% higher than that of the first zone 34a then: d2= d3/1.35.

In all other respects the heating element layer is substantially identical to the heating element layer 8 shown in Figs. 2 and 3. Accordingly the first heating filament 34a and the second heating filament are both serpentine or sinuous heating filaments and connected together to form a single continuous heating element. Features of the first embodiment, such as differences in heating filament width could be combined with features of the second embodiment, such as different distances between adjacent lengths of the heating filaments in the first and second zones.

-13 - [0031] In the heater element layers shown in Figs. 2, 3 and 4, in a boundary region 42 between the first and second zones, portions of the heating element in the first zone 30 are interdigitated with portions of the heating element in the second zone 32. This arrangement is only shown in Fig. 2 but has not been shown in Figs. 3 and 4 since they do not show the precise routes taken by the first and second heating filaments. This arrangement of filaments results in the temperature transition between the first and second zones being less abrupt than it would be without such interdigitation.

[0032] A specific example of suitable heating filament dimensions for a heating element of a heater mat such as that shown in Fig. 2 is given below. The heating filaments are all made of stainless steel and have a thickness (i.e. the dimension perpendicular to the major plane of the heater mat) of around 0.04 mm. In the first zone 30 the first filament 34 has a width of around 1.5 mm and a gap between adjacent lengths of the filament of around 1.0 mm. In the second zone 32 the second filament 36 has a width of around 1.0 mm and a gap between adjacent lengths of the filament of around 1.0 [0033] The method of producing chemically etched foil conductors in heating elements layers such as those described above are well known in the art and will accordingly not be described in complete detail as are the methods for producing heating element layers containing wire conductors. Such heating element layers or mats could suitably be those of the type manufactured by Holroyd Company Ltd, Units 10-12, Shire Hill Industrial Estate, Saffron Walden, Essex, CB11 3AQ, United Kingdom.

-14 - [0034] An overview of the process involved in the production of the heating element layer 8 for incorporation into a heater mat 2 according to the invention will be described below. Firstly a stainless-steel foil around 0.04 mm thick is bonded to the glass-fibre reinforced outer silicone layer 26 with thermosetting adhesive at an elevated temperature and pressure. Secondly a photoimageable resist layer is applied to the foil layer. Thirdly a mask is applied to the resist layer in a pattern which defines the heating elements. Gaps are left in the mask where heating element material is to remain. This step is customarily performed using computer controlled deposition of the mask material. Fourthly curing ultra-violet light is shone onto the mask and cures the resist layer where it is exposed by the mask. Fifthly the non-cured resist is removed. Sixthly a series of chemical etching, stripping and cleaning cycles are performed to remove foil portions not protected by the cured resist while leaving the required pattern of heating element(s) adhered to the outer silicone layer 26. Seventhly a so-called coverlay or inner layer 27 of glass-fibre reinforced silicone is adhered over the outer silicone layer 26 with the etched foil heating element sandwiched between these two layers. The inner layer 27 is secured in place with thermosetting adhesive and has apertures therein to permit access to the contact pads 24. Finally conductors of the power cable 38 are soldered or otherwise electrically connected to the contact pads 24.

[0035] The steps used to produce a heater mat according to the first aspect of the invention from a heating element layer 8 or 8a as shown schematically in Figs. 2, 3 and 4 respectively will be described with particular reference to Figs. 5 to 12.

-15 - [0036] Fig. 5 -An externally facing surface of the outer layer 26 of the heating element layer 8 (which may be of the type shown in Figs. 2, 3 or 4) is thoroughly cleaned with a suitable agent such as isopropyl alcohol cleaner.

[0037] Fig. 6 -One face of the insulation layer 10 is also thoroughly cleaned, with a suitable agent such as isopropyl alcohol cleaner.

[0038] Fig. 7 -Adhesive, such as Momentive RTV108 (RTM), is applied to the cleaned surface of the insulation layer 10.

[0039] Fig 8. -The adhesive is spread out over The surface of the insulation layer 10 with a bladed tool 46.

[0040] Fig. 9 -The insulation layer 10 is placed over a flexible steel band clamping collar 48.

[0041] Fig. 10 -The glued surface of the insulation layer 10 is placed around the heating element layer 8 which is in turn placed around a mandrel 50. Confronting flanges 52 of the clamping collar 48 are urged towards each other.

[0042] Fig. 11 -A clamp 54 is used to clamp the two flanges 52 of the clamping collar towards each other which in turn urges the glued surface of the insulation layer 10 into intimate contact with the cleaned outer surface of the heating element layer 8. The heater mat is left in this state for approximately 12 hours to allow the glue to set.

[0043] Fig. 12 -The clamp 54, the clamping collar 48 and the mandrel 50 are removed from the heater mat 2 and an incision 56 of approximately 3mm is made between the heating element layer 8 and the insulation layer 10 along the entire -16 -lengths of the third side 18 and the fourth side 20 of the heater mat. These two layers are forced apart and a bead of glue such as Momentive RTV108 (RTM) is inserted between the heating element layer 8 and the insulation layer 10. Alternative resilient spacing means could be used for this purpose. The heater mat 2 is then ready for use.

[0044] The use of the heater mat 2 to print an image on a mug will now be described with reference to Figs. 13 and 14.

[0045] Fig. 13 shows the items used to print an image on a mug. These items include: (i) a clamping collar 48; (ii) the heater mat 2 according to the invention; (iii) a image transfer membrane (which may be made of coated heat resistant paper) and on which a reverse image 62 has been printed with ink suitable for sublimation printing; and (iv) a mug 4. These items are assembled as shown in Fig. 14, that is with the clamping collar 48, surrounding the heater mat 2, which surrounds the image transfer membrane 60 which surrounds and contacts an outer surface of the mug 4. The flanges 52 of the clamping collar 48 are urged towards each other to press the heater mat 2 inwardly so that it clamps the image transfer membrane 60 firmly against the outer surface of the mug 4. This clamping could be performed with screw-threaded fasteners as shown in Figs. 13 and 14 or in an automated process could appropriately be performed using an actuator such as a pneumatic or hydraulic actuator. The plug 28 on the power cable 38 is then connected to a source of electricity for a suitable time to allow the heater mat 2 to heat up the image transfer membrane 60 and the mug 4 such that the image 62 (or a portion thereof confronting the mug 4) is printed onto the mug by a process of sublimation image transfer. For a typical mug and image transfer membrane, the heater mat is heated up to about 180°C which takes -17 -approximately 3 minutes and maintained at this temperature for approximately 30 seconds.

[0046] The higher energy output of the second zone of the heater mat relative to that of the first zone thereof enables an operator to control the temperature of different parts of the mug such that sufficient heat is provided to heat sink areas adjacent the handle and the base of the mug thereby ensuring that image fade does not occur in these regions while ensuring that other areas of the mug do not become overheated and thereby suffer from image bleeding in which colours unintentionally mix with each other.

[0047] In the above process the third side 18 and the fourth side 20 of the heater mat, including the spacer fillets 58, are arranged adjacent to the handle of the mug and act to press the heater mat particularly firmly into contact with the mug in this area where the handle acts as a heat sink. This improves heat transfer between the heater mat and the mug in this area. The first side 14 of the heater mat is arranged adjacent to the base of the mug. The portion of the second heating zone adjacent this first side 14 is accordingly able to deliver additional heat to this region of the mug where the base of the mug acts as another heat sink.

[0048] The use of the heater mat 2 according to the invention allows the process of transferring an image onto a mug which is well suited to automation while avoiding the printing problems associated with variations of temperature between different parts of the mug resulting from some regions of the mug acting as heat sinks. A camera in combination with automated image processing, can be used in an automated printing process to ensure the correct -18 -juxtapositions of the items described above as the automated process progresses.

Claims

-19 -CLAIMS1. Drinking mug image transfer heater mat including a heated region including a first zone and a second zone and at least one resistance heating element for heating the first and second zones wherein the at least one resistance heating element is configured to supply a first energy output per unit area of the heated region in the first zone and a second higher energy output per unit area of the heated region in the second zone.
2. The heater mat of claim I wherein the second energy output is at least 20% higher than the first energy output.
3. The heater mat of claim 2 wherein the second energy output is at least 30% higher than the first energy output.
4. The heater mat of any preceding claim wherein the at least one resistance heating element comprises only one continuous heating element.
5. The heater mat of any preceding claim wherein the at least one heating elemenr_ comprises a heating filament having a first cross-sectioned area in the first zone and a heating filament having a second smaller cross-sectional area in the second zone.
6. The heater mater of any preceding claim wherein the at least one heating element includes a first heating filament disposed at a first overall filament length per unit area in the first zone and a second heating filament -20 -disposed at a second higher overall filament length per unit area in the second zone.
7. The heater mat of claim 6 wherein the at least one heating element is entirely constituted by filament material haying a substantially uniform cross-sectional area.
8. The heater mat of any preceding claim wherein the at least one heating element comprises at least one foil heating element.
9. The heater mat of claim 8 wherein the at least one heating element comprises at least one etched foil heating element.
10. The heater mat of any preceding claim including a heating element layer including the at least one heating element in a medium including glass fibre reinforcement.
11. The heater mat of any preceding claim including a heating element layer including the at least one heating element and an insulation layer.
12. The heater mat of claim 11 wherein in a perimeter region of the mat a spacer is provided between the heating element layer and the insulation layer to space these layers further from each other than in a central region of the mat.
13. The heater mat of any preceding claim wherein the heater mat has a substantially quadrilateral perimeter having four sides, the heated region extends to adjacent all four sides thereof and the first zone of the heated -21 -region only borders at least a majority of one of the sides but does not border any of the other sides.
14. The heater mat of any preceding claim wherein, at a boundary region between the first zone and the second zone portions of the heating element of the first zone are interdigitated with portions of the heating element of the second zone.
15. A method of transferring an image onto a drinking mug including: (i) providing an image on an image transfer membrane; (ii) providing an image transfer heater mat including at least one resistance heating element and a heated region including a first zone configured to supply a first energy output per unit area of the heated region and a second zone configured to supply a second higher energy output per unit area of the heated region; (iii) urging the heater mat towards the drinking mug with the image transfer membrane positioned between the heater mat and the drinking mug; and (iv) heating the heater mat by means of the at least one resistance heating element to transfer the image onto the drinking mug.