Patent Application
20160305807
The present invention relates to a consumption meter, such as an ultrasonic flow meter, comprising a printed circuit board assembly, which can be folded to form a compact assembly extending in three geometric planes.
A well-known physical limitation, which can be hindering the efforts of reducing the physical size of wireless consumption meters, is the fact that the radio frequency (RF) antenna used for communication with a distant central control unit requires certain dimensions in order to obtain the appropriate resonance frequency of the antenna. Although it is possible to make RF antennas with smaller physical dimensions than normal for a given resonance frequency, it is a well-known problem that the efficiency of such small antennas is not very high.
It is an object of the invention to provide a solution, which overcomes or at least reduces the above-mentioned problem.
The present invention relates to a consumption meter comprising a foldable printed circuit board assembly, which foldable printed circuit board assembly comprises a printed circuit board substrate having at least a first and a second rigid part, wherein electronic components and a battery are mounted on the first rigid part, which also comprises an electrical ground plane, and a radio frequency (RF) antenna extends mainly on the second rigid part, a first flexible part of the printed circuit board substrate being arranged to allow the printed circuit board assembly to be folded so that the first and second rigid parts extend in two different but substantially parallel geometric planes.
In an embodiment of the invention, the first flexible part connects the second rigid part to a third rigid part of the printed circuit board substrate onto which a part of the RF antenna extends, the third rigid part being configured to extend in a geometric plane substantially perpendicular to the geometric planes in which the first and the second part extend when the printed circuit board assembly is folded.
The use of a folded printed circuit board assembly means that a more compact and less space-consuming printed circuit board assembly and consumption meter construction can be obtained. This is especially important for flow meters, in which the electronics must be protected from moisture and water, typically be embedding or enclosing the electronics in a watertight enclosure. In this relation, smaller volumes means less production costs.
Folding the printed circuit board as described means that a box-shaped folded assembly with the electronic components places inside the “box”, i.e. between the two rigid parts extending in parallel planes, can be obtained. Such a shape of the assembly means that it is well-suited for being installed in many different places, such as consumption meter housings, which are often box-shaped.
Furthermore, the arrangement of the electrical ground plane and the RF antenna on two rigid parts of the printed circuit board substrate, respectively, which extend in two different but substantially parallel geometric planes means that, if the printed circuit board assembly is appropriately oriented within the consumption meter, the ground plane on the first rigid part can be placed between the RF antenna and the flow channel. Thus, the ground plane works as a stable electrical counterweight for the RF antenna and the same type and size of RF antenna can be used for different sizes of consumption meters. In other consumption meters known from the art, this electrical counterweight is formed by the ground plane on a printed circuit board itself and/or a flow channel through which a fluid to be metered flows. In that case, the RF antenna must be dimensioned depending on the size of the consumption meter in order to match the actual electrical counterweight. Furthermore, an electrical counterweight involving a non-conductive flow channel, for instance made of a plastic material, is less stable due to fact that the performance will depend on whether a conductive fluid, such as water, is actually present within the flow channel or not.
Another advantage obtained by orienting the printed circuit board assembly as described is that the RF antenna gets the maximum possible free space in relation to the conductive parts in the consumption meter including the electronic components on the first rigid part of the printed circuit board substrate resulting in optimal radiation characteristics of the RF antenna.
Letting the RF antenna extend in two different geometric planes of the folded printed circuit board assembly has surprisingly shown to result in the effect that an RF antenna with a given resonance frequency can be made shorter than otherwise expected, meaning that a more compact printed circuit board assembly, which takes up less space, for instance in an installation box in which the assembly is installed, can be obtained.
In an embodiment of the invention, a second flexible part is arranged to connect the first rigid part and the third rigid part to each other.
Using such configuration, the complete printed circuit board substrate can be produced in one piece, which reduces the production costs.
In an embodiment of the invention, an electrical connector is inserted between the first and the third rigid part of the printed circuit board substrate and arranged to releasably connect the first and the third rigid parts to each other.
The releasable connection between the first and the third rigid part of the printed circuit board substrate to each other means that a given first rigid part of the printed circuit board substrate being equipped with a standard set of electronic components can be combined with different sets of second and third rigid parts comprising RF antennas of different lengths and, thereby, different frequency bands, respectively. Thus, the flexibility of the system is increased.
In an embodiment of the invention, the third rigid part comprises an electrical ground plane.
Letting the electrical ground plane extend onto the third rigid part further increases the counterweight properties of the ground plane and further reduces the influence of the size of the flow channel.
In an embodiment of the invention, the RF antenna extends on the inner side of the folded circuit board assembly, i.e. on the side of the second rigid part of the printed circuit board substrate facing the first rigid part and, where applicable, on the side of the third rigid part of the printed circuit board substrate facing the first and the second rigid parts.
Letting the RF antenna extend on the inner side of the folded circuit board assembly, i.e. on the same side as the electronic components, means that the RF antenna can be connected directly to the relevant electronic components without having the antenna signal passing through the printed circuit board substrate from one side thereof to the other. This is advantageous because the so-called vias used for making electric connections through a printed circuit substrate can be detrimental for high frequency signals due to the fact that the physical structure of the vias causes them to represent uncontrollable inductances.
In an embodiment of the invention, the foldable printed circuit board assembly further comprises a Near Field Communication (NFC) antenna extending mainly on the second rigid part of the printed circuit board substrate.
The inclusion of an NFC antenna enables for simple and easy communication with other electronic devices, for instance for receiving simple commands and the like from external devices. For the NFC antenna, it is even more important than for the RF antenna that the radiation characteristics are optimized as described above.
In an embodiment of the invention, a cutout is made in the second rigid part of the printed circuit board substrate so that a display, which is mounted with the other electronic components on the first rigid part thereof, is clearly visibly through the cutout in the second rigid part, when the printed circuit board assembly is folded.
Such a configuration allows the second rigid part carrying the main part of the RF antenna and, where relevant, also the NFC antenna, to be placed on top of the folded printed circuit board assembly without blocking the sight to the display mounted on the first rigid part arranged there below.
In an embodiment of the invention, the electronic components constitute the necessary electronics to drive and control a consumption meter, such as an ultrasonic flow meter.
In an embodiment of the invention, the consumption meter is an ultrasonic flow meter, such as a water consumption meter, a gas consumption meter or a heat consumption meter.
In the following, an exemplary embodiment of the invention is described in more detail with reference to the figures, of which
In the illustrated embodiment, a number of electronic components 8, a battery (not specifically indicated in the figures), an NFC antenna 9 and an RF antenna 10 are mounted on a printed circuit board substrate consisting of five different parts 2-6. Three rigid parts 2-4 are separated from each other by two flexible parts 5, 6. The electronic components 8 are mounted on the first rigid part 2 of the printed circuit board substrate, and the two antennas 9, 10 extend mainly on the second rigid part 3 but also partly on the third rigid part 4 of the printed circuit board substrate.
The second rigid part 3 of the printed circuit board substrate comprises a through-going cutout 11 to make a display (not shown in any of
The fact that the flexible parts 5, 6 of the printed circuit board substrate are bendable means that the printed circuit board assembly 1 can be folded to form a very compact box-shaped assembly as illustrated in
As illustrated in
As can be seen from
The illustrated embodiment of an ultrasonic flow meter 15 is just to be seen as one example of consumption meters or other electronic devices in which a folded printed board assembly 1 as described above can be used.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/DK2013/050408 | 12/3/2013 | WO | 00 |
