Expert Evidence
47 Three experts gave evidence at the trial. Bitech called Dr Ian Cowling, who is an Associate Professor in the School of Physical and Chemical Sciences of the Queensland University of Technology (QUT). His field of expertise is optics, which is the study of the behaviour and properties of light. He has been involved in that field for more than 25 years. The respondents called Professor Keith Nugent, who is the Laureate Professor of Physics and Federation Fellow, Executive Research Director, ARC Centre of Excellence for Coherent X‑Ray Science in the School of Physics at the University of Melbourne. Professor Nugent said that he was expert in the field of optical methods and technologies. The respondents also called Professor Tanya Monro, who is the Professor of Physics with the Chair of Photonics and a Director of DSTO Centre of Expertise in Photonics, School of Chemistry and Physics at the University of Adelaide.
48 Each expert was amply qualified in the relevant field of physics, although none of the experts had ever been involved in the design or manufacture of heaters or devices endeavouring to simulate flame effects.
49 In his first affidavit, Dr Cowling gave a succinct but very helpful synopsis of the behaviour and properties of light insofar as those matters are relevant to the present proceedings. At pars 23-28 of that affidavit, Dr Cowling said:
23 Light is a form of energy, or radiation, that is generally accepted as having the properties of waves. A beam of light is actually a number of different waves travelling through the air (or other medium) together. From a scientific perspective, light behaves in a predictable manner.
24 Energy that has the properties of waves, such as light, will be partially transmitted and partially reflected at the boundary or surface between any two media. Generally speaking, when a beam of light strikes the surface of a new medium (or substance), two things happen. Some of the energy will be reflected off the surface of the new medium in the form of reflected light, and some energy will be transmitted through or absorbed into the new medium. In effect, what this means is that all surfaces reflect light to some degree. Conversely, no surface reflects 100% of light, because some of the energy is always absorbed.
25 At its simplest, reflection of light is the change in the direction of light waves when they hit a surface and bounce off it, retaining their energy. Because not all of the light is reflected, the intensity of the reflected light decreases. This will be the case if that light is again reflected off another surface, with the intensity of the light decreasing with each incident of reflection. The amount of reflection that there is occurring, and consequently the decrease in intensity of the reflected light, depends on the nature of the surface that the light is hitting.
26 It is generally accepted that there are two types of reflection - specular and diffuse reflection:
26.1 Specular reflection occurs when light is reflected off a smooth surface (such as a mirror, glass or other shiny surface). The waves of light remain concentrated during specular reflection, and are reflected uniformly off the surface in a particular direction rather than being scattered in different directions. This creates an image behind the surface that can be detected by the eye. The most obvious example of this is an image in a mirror.
26.2 Diffuse reflection occurs when a wave of light is reflected off rough surfaces (such as wood, walls or fabric), and scatters in different directions. While this may (depending on the degree of scattering that takes place) be sufficient to produce an outline of an image on the surface, it is not the clear mirror image that can be seen in the case of specular reflection.
27 It is possible to measure the reflection and transmission of light from different materials, and I have the capability to do so at QUT's Photometric Laboratory. Through my experience in conducting such measurements, I am generally aware of the reflective qualities of different kinds of materials. By way of example, from my own knowledge and experience, I am aware that glass typically has a reflectivity of about 8% (that is, it reflects about 4% as it enters and another 4% as it emerges from the glass, with the remaining light being transmitted through or absorbed into the glass).
28 When light encounters an obstacle in its path which is not transparent (so that it does not transmit light, as for example glass does), the obstacle, to a significant degree, tends to block the light waves. Some of the light waves will be reflected off the obstacle and some will be absorbed by the obstacle. In addition, however, some light will diffract (bend) around the edges of the obstacle, which is why shadows can have what appear to be fuzzy edges. Diffraction is the change of direction of waves as they pass around an obstacle or barrier.
50 The matters set out in the paragraphs of Dr Cowling's first affidavit which I have extracted at [49] above were not controversial. Professor Monro agreed with Dr Cowling's exposition. She also agreed with Dr Cowling's opinion that those matters were part of the common knowledge of persons with an undergraduate qualification in the field of optics in Australia prior to 10 February 1989 and as at late 2008.
51 In his first affidavit, Dr Cowling went on to set out his understanding of the essential features of the invention the subject of the Patent in order to provide an appropriate setting for evidence which he gave later in the same affidavit concerning particular features of the respondents' heaters. Dr Cowling then analysed particular features of a number of those heaters and expressed views as to whether or not those heaters infringed the Patent.
52 In his first affidavit, Dr Cowling dealt with the following electric flame effect heaters which came to be known by reference to their model numbers, namely, BH1, BH2, BH4, BH5, BH6, BH7, BH9, BH10, BH12, MS-5 and FG150.
53 Dr Cowling testified that he had personally inspected physical samples of each of those heaters with the exception of that described as BH5. He had only looked at photographs of that heater. One of the conclusions which Dr Cowling reached after inspecting each of those samples was expressed as follows:
Although the size, casing and exterior presentation of the various models of the Electric Flame Effect Heaters which I have inspected are different, I am satisfied from my inquiries that each contains an apparatus for simulating flames which is essentially the same between the various models.
54 Dr Cowling fleshed out that conclusion by describing the essential features of each of the respondents' heaters (moving from the back of the apparatus to the front), as follows:
60. In particular, each of the Electric Flame Effect Heaters include the following features (moving from the back of the apparatus to the front):
60.1 a source of light, being one light globe in the smaller models or two light globes in the larger models, situated in a rotating cylinder;
60.2 a rotating cylinder with zig zag shaped apertures (approximately 1.5mm x 17mm); in the case of Garth Living Electric Flame Effect Heater Reference No. BH6, Fineline 4440175 (referred to in paragraph 57.5 above), and Garth Living Electric Flame Effect Heater Reference No. BH12, Fineline 4440191 (referred to in paragraph 57.9 above), the cylinder has both a set of zig zag shaped apertures (approximately 1.5mm x 17mm), and an alternate row of approximately 6 smaller flame shaped apertures (approximately 8mm x 5 mm).
60.3 with the exception of Garth Living Electric Flame Effect Heater Reference No. BH12, Fineline 4440191 in which this feature is absent, a metal plate with a flame shaped cut out, similar to a stencil of flames emanating from a fire, situated between the light rotating cylinder and a screen;
60.4 a screen, positioned between the metal plate with the flame shaped cut out and a bed of simulated log and/or coal fire, consisting of a panel of glass with either a film of translucent plastic material adhered to the glass, or a matt, sandblasted finish that faces backwards towards the metal plate with the flame shaped cut out, and a semi-mirrored finish facing the bed of simulated log and/or coal fire;
60.5 a bed of simulated coal and/or log fire.
55 Dr Cowling described the flame effect presented to an observer looking at the front of the heater as follows:
When they are in operation, a simulated flame is visible on the screen from the front of the heater. The flame appears to emanate from between the simulated fuel and the reflection of the simulated fuel bed that appears at the bottom of the screen.
56 In the respondents' heaters, the source of light is the filament in a light globe housed in the rear chamber of the appliance. In all but one of those heaters, that light globe is situated within a rotating cylinder made of plastic and finished with a matt black coating. The Flameglow FG150-2 model heater has a shiny stainless steel cylinder, not a plastic matt black coated cylinder. In all models, the rotating cylinder is located behind the viewing screen. That screen is used to transmit light and to project the flame image to the observer looking at the heater from the front. The light from the light globe is initially radiated in a number of directions within the cylinder. Dr Cowling said that some of that light passes out through some of the apertures in the cylinder and into the rear chamber of the appliance. In his view, the simulated flames in the respondents' heaters are produced by the combined operation of the light globe, the rotating cylinder with apertures, a metal plate with a flame shaped cut out, the interior surfaces of the rear chamber and the viewing screen on which the image of the flames is seen. In all but one of the respondents' heaters (heater BH12), there is a flame shaped cut out metal plate located behind the viewing screen but above the rotating cylinder.
57 Dr Cowling accepted that some of the light which hits the rear of the screen to produce an image of simulated flames on the screen is directly emitted from the light source, in the sense that it passes from the filament of the light globe, out through some of the apertures in the rotating cylinder (those located towards the middle of the length of the cylinder), through the flame shaped cut out plate and onto the screen without hitting any surface in between. That light is not reflected off any surface within the chamber or compartment which houses the apparatus. Dr Cowling said that the light which is directly emitted from the light source onto the screen produces relatively bright images on the screen which reflect the shape of the apertures in the rotating cylinder. He said that these images appear to be moving because of the rotation of the cylinder. Dr Cowling also said that:
Other light reaching the screen is reflected light, in the sense that it reflects from one or more surfaces in the rotating cylinder and/or the rear chamber, before making its way to the back of the screen. This reflected light is of lower intensity and produces weaker and more diffuse images on the screen which are dispersed around the brighter images produced by the directly emitted light, adding to the realism of the simulated flames.
58 The statement which I have quoted at [57] above is at the heart of such controversy as there was between the experts called by the parties at the trial in relation to infringement. Dr Cowling contended that a substantial part of the flame effect that can be observed from the front of the heater by someone looking at the heater is contributed to by reflected light. In their affidavit materials, the experts called by the respondents asserted that the contribution to the flame effect seen on the screen made by reflected light is almost zero or is, at most, negligible, and that reflected light only creates a static background glow which, although part of the image, is not part of the flame effect itself because it does not have the necessary shape nor does it give the necessary impression of movement.
59 At pars 66-69 of his first affidavit, Dr Cowling said:
66 In more detail, a number of things are happening simultaneously in the operation of the heater, as follows:
66.1 As identified above, all surfaces are reflective. The light being emitted from the light globe that hits the rotating cylinder itself will be both partially reflected from, and partially absorbed into, the cylinder.
66.2 Some of the light radiating from the light globe will be emitted directly out through the apertures in the rotating cylinder.
66.3 Some of the light that hits the internal surface of the rotating cylinder will reflect off that surface inside the cylinder. A percentage of this reflected light will ultimately pass out of the apertures in the cylinder.
66.4 Once light is emitted through the apertures, some will pass directly through the flame shaped cut out in the metal plate and hit the back of the screen. Some light will hit the interior surfaces of the rear chamber or the metal plate itself. Some of this light will be reflected off those surfaces, and may ultimately pass through the flame shaped cut out and hit the back of the screen, while some light will be absorbed.
66.5 Some of the light that passes through the apertures and the flame shaped cut out in the metal plate will be diffracted around the edges of the apertures and the cut out, although I would expect such diffraction to produce only a minimal effect.
66.6 As identified above, the light that is transmitted through the screen will be diffused due to the partially diffusing surface.
67 In my opinion, the rotating cylinder and the metal plate with the flame shaped cut out have a number of functions. The rotating cylinder creates a varying obstacle for the light radiating from the light globe. The light that is ultimately viewed on the screen is made more random, and therefore realistic, by the shaped apertures in the metal cylinder, and the flame shaped cut out in the metal plate. These features work together to direct light from the light source to the back of the screen in a manner which, in my opinion, simulates a more realistic flame effect.
68 I have made some detailed observations in relation to my inspection of the Flameglow FGI50 Floor Standing Model with Glass Door. I noted that, as the cylinder rotates, there is at any one time, only one set of apertures along the cylinder which faces in the direction of the screen. Of this one set of apertures, approximately half of these apertures (being the centre three or four) allow light to pass directly through the flame shaped cut out of the metal plate and onto the screen. The other half of the apertures facing the screen, and the apertures facing in different directions, allow light out of the cylinder into the rear chamber of the apparatus, where it is reflected off surfaces.
69 When considering the total area of the screen on which one views the simulated flame effect in the Electric Flame Effect Heaters, I estimate that approximately equal areas of the screen are illuminated by directly emitted light (passing through the centre three or four apertures facing the screen) and by less intense reflected light. In this regard, my observations in relation to the Flameglow FG150 Floor Standing Model with Glass Door indicate that approximately 30% to 40% of the area of the screen in the line of one set of apertures is illuminated by light emitted from the centre three or four apertures facing the screen - that is, directly emitted light. A further 40% of that area of the screen in that heater is illuminated by less intense reflected light, and the remaining part of that area of the screen (20% to 30%) is not illuminated at all. I have set this out schematically in the following diagram:
60 Dr Cowling said that his assessment set out in par 69 of his first affidavit applied to all of the models of heaters which he inspected.
61 As mentioned in [56] above, one of the models of the respondents' heaters, the Flameglow model FG150-2 tendered in evidence, has a silver or polished stainless steel rotating cylinder as part of its mechanism instead of a cylinder with the matt black finish used in the other models inspected by Dr Cowling. Dr Cowling said that the apparatus in that particular model of heater generates a brighter simulated flame effect image and illuminates a greater area of the screen with reflected light than does the apparatus in those models which have matt black finished rotating cylinders. This is because the shiny stainless steel surface of that particular rotating cylinder has a much higher reflectivity than the matt black surface of the cylinders in the other models.
62 At par 78 of his first affidavit, Dr Cowling said:
With regard to paragraph 77.2 above and the simulated flame effect means, as explained in paragraph 69 above, in my opinion the simulated flame effect in the Electric Flame Effect Heaters is achieved by a contribution of directly emitted and reflected light. While the majority of the light reaching the screen is directly emitted light that is more intense than the reflected light, the area of the screen which is illuminated by each is, in my opinion, approximately equal (as explained in paragraph 69 above). The directly emitted light, being more intense than the reflected light, produces the brightest images on the screen. However, reflected light also makes a significant contribution to the flame effect. The light that is periodically emitted through the shaped apertures, in combination with the contrasting glow of the less intense, reflected light, achieves the object of simulating flames arising from a bed of combusting fuel. Without the reflected light, the screen would only be illuminated with intermittent flashes of directly emitted light. In my opinion, reflected light makes a significant contribution to achieving the objective of a more realistic flame effect.
63 Dr Cowling said that the simulated flame effect in the respondents' heaters could not be achieved without a significant contribution from reflected light. In his opinion, therefore, those devices employed the same principle as is embodied in the Patent.
64 In affidavits subsequently sworn by Dr Cowling, he related the views which he had expressed in his first affidavit to two further models of electric flame effect heaters namely, the Flameglow model FG100 and the Flameglow model FG400. He also updated his views about the heater BH5 based upon an inspection of a sample of that heater and not merely upon the photographs of the model which he had previously used in order to found his opinions. In effect, Dr Cowling said that the observations which he had made in his first affidavit applied equally to those additional models.
65 Professor Nugent provided one affidavit which was mostly directed to the Cross-Claim for revocation of the Patent brought by Garth Living. In two additional affidavits, he also expressed some opinions directed to the issue of infringement.
66 In his affidavits addressing issues related to infringement, Professor Nugent said that the simulated flame effect is produced in the respondents' heaters by a combination of the operation of the rotating cylinder, the viewing screen and the flame shaped metal plate. These items allow light from the light source in the globe to form patterns of light on the screen that mimic the form of natural flames. In his view, although some light will inevitably be reflected from the surface of the interior of the rotating cylinder, such reflection will be a diffuse reflection and will detract from the flame effect by contributing a featureless bright background and not contribute much, if at all, to the flame effect depicted on the screen. In his affidavit material, Professor Nugent stated unequivocally and in an unqualified manner that:
A diffuse reflection will not contribute to the flame effect. The interior of Rotating Sleeve B has been treated so as to effectively eliminate reflected light.
67 The essence of this opinion, as I understood it, was that, because the rotating cylinder is made of plastic and coated with a matt black finish, almost no reflected light is generated from that cylinder. Professor Nugent went on to conclude that specular reflection from the interior of the rotating cylinder would be negligibly small. Professor Nugent conducted an experiment in order to assess the contribution that diffuse reflection made to the flame effect in the respondents' heaters. In light of his experiment, he concluded that reflections from the interior of the rotating sleeve do not contribute to the flame effect in the respondents' heaters. He went on to conclude that:
… the mechanism in the Electric Flame Heaters involves only transmission of light through apertures, a quite distinct physical mechanism from reflection of light.
68 In his third affidavit, Dr Cowling took up the challenge thrown out by the views of Professor Nugent which I have summarised above. Dr Cowling amplified his assertion that other surfaces within the compartment of the device, including the inner surface of the rear panel, provide reflective surfaces for the purposes of conveying light from the light source (the filament in the globe) through the rotating cylinder and ultimately to the screen. Dr Cowling said that he disagreed with Professor Nugent that reflection has been effectively eliminated in the respondents' heaters by means of the matt black finish on the rotating cylinder. Further, Dr Cowling disagreed with Professor Nugent that a diffuse reflection will detract from and not contribute to the flame effect depicted on the screen. Dr Cowling conducted tests which depended upon a visual and measurement assessment of three of the respondents' heaters in order to ascertain the contribution made by the reflected light to the flame effect depicted on the screen. As a result of these tests, Dr Cowling reaffirmed his view that reflected light does contribute to the observable illumination of a significant proportion of the screen during operation of the respondents' heaters. He estimated that proportion to be of the order of 40% of the screen area.
69 Professor Nugent subsequently swore his third affidavit. In that affidavit, he concluded that:
(a) Reflections off the inner surface of the rear outer casing of the respondents' heaters do not contribute at all to the flame effect depicted on the screen; and
(b) The flame effect in those heaters is created entirely by the direct transmission of light produced by the light globe located within the rotating cylinder passing through the flame shaped holes cut in that cylinder and striking the viewing screen.
In part, these conclusions were based upon certain experiments conducted by Professor Nugent.
70 In her first affidavit, Professor Monro concentrated on the Flameglow FG150 model with the matt black finished rotating cylinder. In dealing with the question of the degree to which reflected light contributed to the flame effect on the screen in the respondents' heaters, Professor Monro said the following, in respect of the Flameglow FG150 heater:
I do not agree with the conclusions described in paragraphs 63-75 inclusive [of Dr Cowling's first affidavit] and the additional material in Exhibit IRC-6. In particular, I disagree with Dr Cowling's interpretation of the amount of contribution that reflected light makes to the overall image of the simulated flames. My direct observations of the FG150 Heater were that the patterns visible from the front are not due to reflections either within the cylinder or within the chamber behind the screen, and are instead predominantly due to the direct transmission of light through the slits and then the metal plate. The contribution of the reflected light is minimal, and while not zero, it makes little contribution to the overall patterns observed from the front of the heater while the apparatus is operational.
71 Professor Monro went on to explain those remarks in the succeeding paragraphs of her first affidavit. She accepted that some light reaching the screen is light which is reflected internally but contended that very little of the light reaching the screen is in that category. She said that the limited reflections that occur from matt black surfaces are predominantly diffuse light and that diffuse light emerging from the apertures cannot produce a clear image of the apertures on the screen. She said that that type of light emerging from the apertures acts only to increase slightly the overall illumination on the screen.
72 Dr Cowling answered Professor Monro's first affidavit in his fifth affidavit (one of the affidavits sworn by him on 3 March 2008). He observed that the dominant type of reflection which was observable on the screen of the respondents' heaters is not specular reflection, but is diffuse reflection. He repeated his contention that all surfaces, including matt black finished surfaces, reflect light to some degree. He took issue with Professor Monro's assertion that the appearance of the flames to the eye of an observer placed in front of the unit is qualitatively similar, regardless of whether the back panel is fixed to the unit or not. On the critical question for present purposes, Dr Cowling said:
… reflected light does contribute to the observable illumination of a significant proportion of the screen during the operation of the Electric Flame Effect Heaters. Whether the reflected light dispersed around the brighter images gives a more realistic flame effect is a matter of opinion for the viewer. In my opinion, as stated in my First Affidavit, reflected light does make a significant contribution to achieving the objective of a more realistic flame effect.
73 Dr Cowling went on to say that the reflected light hitting the viewing screen improves the image and makes it more realistic in the respondents' heaters.
74 In a separate affidavit sworn on 3 March 2008, Dr Cowling said that his essential views as to the contribution which reflected light makes to the flame effect images on the viewing screen in the respondents' heaters applied equally to the one model of Hotpoint heater in issue in the proceedings, namely, the large heater tendered in evidence. The basic workings of the Hotpoint heater are the same as those of the other heaters which are alleged to have infringed the Patent. However, there are some differences which, in light of the decision to which I have come on infringement, need not be traversed.
75 In his final affidavit, Dr Cowling adhered to the views which he had expressed in par 69 of his first affidavit but refined matters somewhat when he said that:
… approximately equal areas of the screen in the FG150 heater with the black rotating cylinder are illuminated by directly emitted light [from the light source] and by reflected light.
76 Dr Cowling explained this conclusion when he went on to say that only the apertures in the middle of the rotating cylinder contributed directly emitted light to the screen and that light passing through the outer apertures on the length of the rotating cylinder hits the outer edges of the compartment and the flame shaped cut out plate and is reflected off those surfaces. He thought that approximately 35% of the screen along the line of the apertures is illuminated by directly emitted light.
77 Dr Cowling was cross-examined at some length by Counsel for Bunnings, Garth Living and Cohen and briefly by Counsel for Hotpoint. The cross-examination of Dr Cowling took place after a demonstration had been conducted in Court during which each of the experts had an opportunity to make observations, ask questions and give testimony. Each of them was sworn for the purposes of providing evidence during that demonstration. Throughout his cross-examination, Dr Cowling adhered to his views that reflected light reaches the viewing screen and contributes to the image of flame depicted on the screen. He said that the reflected light that reaches the screen is reflected light that has been diffusely reflected from behind the screen. He repeatedly adhered to his view that all surfaces both reflect and absorb light and that the extent to which a particular surface did so was always a matter of degree. In cross-examination, Dr Cowling agreed that the plate with the flame shapes cut into it had no role to play in reflection or in creating the time-varying aspect of the flame effect. The plate was simply included in all but one of the respondents' heaters in order to limit the height of the flames to the observer looking at the heater from the front in order to make the flame effect more realistic. He said that all reflective surfaces within the device contribute to the time varying effect of the flame effect shown on the screen. He agreed that there is a significant contribution from directly emitted light to the production of the flame effect in the respondents' heaters. This, of course, was not inconsistent with the evidence which he had provided to the Court in his affidavits.
78 It seemed to me that all of the experts were endeavouring to address the question of whether or not there is a substantial amount of reflected light reaching the viewing screen in the respondents' heaters and being transmitted through that screen and, if so, whether it is contributing substantially to the flame effect shown or depicted on the viewing screen to the observer looking at the device from the front. Various tests were undertaken by the experts in an endeavour to separate out the relative contributions being made to the flame effect depicted on the viewing screen by directly emitted light from the light source through the apertures in the rotating cylinder and by reflected light originating at the same light source but being reflected from the inner surface of the rotating cylinder and other surfaces inside the chamber in which the device is housed.
79 Ultimately, I have benefitted most from the demonstrations which took place on the first and second days of the hearing. That is not to say that the evidence of the experts contained in their affidavits and oral evidence was not significant. That evidence served to crystallise the main issue between Dr Cowling, on the one hand, and Professors Nugent and Monro, on the other hand viz did reflected light contribute substantially to the flame effect depicted on the screen in the respondents' heaters and, if so, in what way and to what extent? That evidence also provided a descriptive analysis and context in which I could assess that contribution for myself during the demonstrations.