The present invention refers to a measuring transducer operating on the basis of the angular position of a set of revolving mechanical elements, or drums, making up part of a meter for measuring fluids, such as gas, or electricity.

5. Transducers in use at present for the above purposes, which are suitable, for instance, to allow digital reading of the numerical indication of the meter, comprise a set of codifying disks, each one associated to a respective drum of the meter, and having a series of slots positioned according to a predetermined binary code.

10. The reading of the angular position of such codifying disks, which are normally of the absolute type, takes place by positioning, in correspondence to one face of each disk, a set of emitter elements of the luminous type, for example, to each one of which a corresponding receiver is associated, for example a photodiode, in

15. correspondence to the other face of the disk. The number of emitters and receivers depends on the type of code used and on the number of divisions foreseen on the periphery of each drum, and may be, for example, four in number for decadal drums.

These known reading systems, precisely because they have many 20. sources of energy, can give rise to mistakes in reading, since it is enough for one single emitter element to be desactivated for any reason whatsoever, to cause false angular reading data.

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One aim of the invention is precisely that of eliminating such a risk of a wrong reading, or at any rate reducing it to a minimum.

Another aim of the invention is to simplify the structure of the transducer device and of the reading means, with consequent 5. reduction in costs.

Another aim is to realize a code which will be simple to carry out on the codifying disks, and which will be easily readable, without the possibility of errors.

In accordance with the invention, one or two radiant souces in 10. series are interposed between two coaxial codifying disks, in such a way as to radiate the opposed surfaces of both and to allow both to be read at the same time.

In such a way, if a source of light interposed between two codifying disks were to be desactivated, it would not allow such disks to be 15. read, and thus eliminate the risks of a false reading.

According to a further characteristic of the invention, the codifying disks consist of the same decadal drums of the meter, with appropriate slots according to a predetermined binary code.

Further characteristics of the invention will be made clearer by the 20. detailed description which follows, referring to one of its purely exemplary and therefore not restrictive embodiments, illustrated in the appended drawings, in which:

figure 1 is a partially sectional schematic front view of a meter with the transducer device according to the invention; figure 2 is a schematic transverse section, taken for example along the line II-II in figure 1 ; 5. figures 3 and 4 are similar views to figure 2 and show, respectively, a codified drum and the detector-carrier element associated to it; figure 5 is an illustration of the particular binary code which is used according to the invention for codifying the digits 10. from 0 to 9 of each drum.

In figure 1 a meter 1 is illustrated consisting of a set of revolving elements- or drums 2, which can have the numeration from 0 to 9 on their peripheral outline, as shown for the first three drums, going from right to left in figure 1. The drums 2 are coaxial 15. and positioned on the same one shaft 3, supported by two opposed side walls of a container 4.

The drums 2, in a way that is already known, are coupled together by means of gears, not shown in the appended figures, in such a way that to each complete revolution of a drum a portion of a revolution 20. of the immediately following drum (a tenth of a revolution in the case of decadal drums) corresponds.

The first drum 2 is set revolving by an entrainment pinion 5, connected in turn to a group of gears which can be set revolving by the passing of a fluid, for example a gas, inside a duct. Therefore

the number of revolutions shown by the meter is correlated with the quantity of fluid which has passed in the duct.

The reading of the consumption of the gas can take place by means of visual reading directly on the meter 1 , when all the decadal drums 5. are provided with respective numerations from 0 to 9 on their periphery, and/or by means of electronic reading, using a transducer device, as in the case of the present invention.

In accordance with the invention, the drums 2, as can be seen in detail in figure 3, are appropriately slotted, thus acting as

10. codifying disks. The codification takes place according to a 4 bit binary code, only one of the 4 changing state when passing from one digit to the next, as shown in figure 5, in which the small squares in heavy print correspond to solid parts of the codifying disk and are shown with reference number 6 in figure 3, and the small white

15. squares, shown with reference number 7 in figure 3, correspond to the slots in disk 2.

Between each pair of codifying disks 2, which are of the absolute type, as is shown in figure 1, only one radiant source is situated, in such a way as to radiate on the opposite surface of such a pair 20. of disks at the same time, and is therefore capable of activating all the detecting means, shown with reference number 9 in the appended figure, associated to such a pair of disks.

The detector elements 9 associated to each drum 2 are borne on a respective support 10, which is shown in figures 2 and 4 with a

triangular outline, only for the sake of example. The arrangement of the detector elements 9 can also vary with respect to the one shown in such figures. In the appended figures reference numbers 8' and 9' indicate the electrical connections of the emitters 8 and 9 5. respectively.

Each emitter 8 is preferably a light radiator, particularly a normal, coherent or infra-red light photodiode, and the corresponding detector elements 9 are receiver photodiods.

As shown in figure 3, a gear wheel 11 can be foreseen on each drum 10. 2, possibly with a multiplication ratio, suitable to activate a second codifying disk acting as a vernier, not illustrated in the appended drawings.

Of course, the invention is not limited to the particular embodiment described above and illustrated in the appended drawings, but many 15. modifications to its details may be made which are within the reach of a technician in the art.