EP 2 952 015 B1 relates to a state of charge indication in a hearing device.
Brief outline of the case
The opposition was rejected and the opponent appealed.
The board interpreted specific features of the claims and decided that claim 1 as granted boiled down to an not allowable intermediate generalisation. All AR suffered the same defect or were not admitted.
The patent was thus revoked.
Technical background
The patent relates to hearing devices having rechargeable batteries, and aims to avoid the user being surprised by a sudden shutdown of the hearing device by informing the user when the battery’s output voltage drops below a certain threshold.
The features at stake are the following
(g) characterized in that the control unit (17) is adapted to control the voltage regulator (16) so as to encode a “signal” in dependence of the rechargeable battery output voltage (V_BATT) onto the supply voltage (V_HI);
(h) and wherein the function module (11) is adapted to decode said “signal” and to determine a state of charge of the rechargeable battery (15) based on said signal.
Interpretation of the claim by the proprietor
The proprietor argued that it was generally accepted that the skilled reader “should try, with synthetical propensity, i.e. building up rather than tearing down, to arrive at an interpretation of the claim which is technically sensible and takes into account the whole disclosure of the patent”.
The proprietor also emphasised that the “patent must be construed by a mind willing to understand, not a mind desirous of misunderstanding”.
Interpretation of the claim by the board
The board considered that the “signal” can be any electrical signal. The skilled reader would understand the expression “in dependence of the rechargeable battery output voltage” used in feature (g) to relate to the way in which the “signal” is encoded. Accordingly, the “encoding” is performed in dependence of the rechargeable battery output voltage, rather than generating the “signal” in dependence of that output voltage. The board gave the example of a signal modulated onto the claimed “supply voltage” in a way that is somehow dependent on the “rechargeable battery output voltage”.
The mere presence of such a “signal” in the claimed supply voltage, irrespective of its content, can suffice for the function module to determine “a state of charge of the rechargeable battery” in accordance with feature (h).
In one scenario, the “control unit” could realistically encode, for instance, a series of random numbers onto the supply voltage for as long as the rechargeable battery output voltage is above a certain threshold. Such random numbers have no bearing on the actual battery output voltage but will allow the “function module” to determine that the battery output voltage and, hence, the associated “charge”, is above the threshold.
The board did not endorse the approach adopted by the OD. It did not consider the description to be a tool for narrowing down the claimed subject-matter to an extent beyond what would objectively occur to the skilled reader based on their common general knowledge from reading the claims alone and referred to T 1924/20, Reasons 2.7. From the board’s perspective, claim 1 as granted does not restrict the “signal” mentioned in features (g) and (h) other than that it should be an electrical signal.
For the OD, feature (g) was considered to imply yielding “an encoded signal” and the “decoding” is considered to act on this encoded signal rather than on the “original” signal mentioned in feature (g).
Mind willing to understand
The board recalled that the frequently used reference to a “willing” skilled reader is about relying on a skilled reader who is prepared to interpret a claim objectively, and not on a skilled reader who is concerned with “understanding” the alleged intention of the applicant or patent proprietor at a certain point in time. The board referred to T 10/22, Reasons 2.3 and T 986/22, Reasons 2.2.3.
The board agreed with the proprietor that the skilled reader would indeed understand feature (g) such that the “signal” is modulated “onto the supply voltage” in a manner in which a typical “modulation/demodulation, or an encoding/decoding process” is conducted. It also accepted that the “signal” according to feature (g) must be consistent with “said signal” in accordance with feature (h).
What matter is the state of charge of the battery and not merely whether the supply voltage is above or below a given level. The latter is however encompassed by claim 1 as granted.
Added subject-matter
The board reminded that when a claim is restricted to a particular embodiment, as is presently the case, it is normally not permitted to extract isolated features from a set of features which have originally been disclosed in combination for that embodiment.
The bord reminded that the context of the entire application as filed directly and unambiguously discloses that informing the user about the need for recharging is a crucial aspect of the invention, not an optional one.
The only mechanism described in the application as filed to achieve this is by encoding actual battery information onto the claimed supply voltage and having the function module decode it to inform the user.
Metaphorically speaking, this means that, like a camel, the “hearing device” described in granted claim 1 operates diligently until it abruptly ceases to function when its battery is depleted. There is no advance warning, similar to how a camel, despite its endurance, can suddenly collapse without prior indication.
Conversely, the original application envisions a “hearing device” akin to a horse. A horse will typically exhibit clear signs of distress or fatigue, like neighing, slowing down or resisting commands, well before reaching its limits.
Similarly, the hearing device described in the application as filed actively communicates its battery status to the user, thereby providing ample warning before a shutdown.
For the board, there would still be no disclosure for the amendment underlying feature (g) that the “control unit” is indeed adapted to control the voltage regulator so as to encode the “signal” onto the supply voltage.
The “control unit” could realistically encode, for instance, a series of random numbers onto the supply voltage for as long as the rechargeable battery output voltage is above a certain threshold. Such random numbers have no bearing on the actual battery output voltage but will allow the “function module” to determine that the battery output voltage (and, hence, the associated “charge”, is above the threshold.
This is because the random-number sequence itself does not inherently convey (“include”) any specific information about the battery’s “state of charge”. Instead, its mere presence or absence in the “supply voltage” indicates whether the battery charge is above or below a predetermined threshold. Crucially, this binary information will typically lack the granularity to provide the user with a timely warning that recharging is necessary.
Comments
It is rare for a board to come to a metaphor in order to show added matter in form of an intermediate generalisation and certainly not to compare the behaviour of camels with that of horses.
The board also reminded that the description cannot be used in order to narrow down the claimed subject-matter. This is a statement which hopefully will be kept in G 1/24.
As for the often used expression mind willing to understand a claim, there I a difference between an objective interpretation of a claim and the understanding of the alleged intention of the applicant or proprietor.
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