Patent Description:
When a packaging container for liquid food such as milk, mineral water, tea, juice, soup, drinks, or the like is produced, a web shaped laminated packaging material may be used. Packaging containers are produced by initial longitudinal sealing of the web shaped laminated packaging material using heat sealing, ultrasonic sealing or the like. For this purpose, a sealing strip may be applied to an edge of the web shaped laminated packaging material. The laminated packaging material can then be formed in the shape of a tube, whereby opposite edges of the laminated packaging material are brought in contact and sealed in the longitudinal direction (lengthwise) in order to close the tube longitudinally.

A filling pipe is typically arranged inside the tube of packaging material through which the desired liquid content is discharged. During continuous production, a partly filled tube is maintained by having a relatively constant level of liquid content in the tube. The partly filled tube is transversely sealed at regular intervals, whereby a series of pillow-shaped preform containers are formed. A preform container is formed into a predetermined shape and separated from the upstream tube, whereby production of a container of packaging material is completed.

Accurate control of the amount of liquid content in the tube is important, particularly with regards to sealing and forming operations to provide the container of packaging material. If the tube is filled with too much liquid content, there will be an increased resistance against the clamping action of the transversal sealing jaws. The increased resistance may also cause damage to the container of packaging material during the final shaping and forming of the container. Examples of damage that may appear due to the increased resistance are e.g. cracks, breaks and the like in the sealed portions of the packaging material. Moreover, if the amount of liquid in the tube exceeds a certain level, there is an imminent risk of overfilling the tube. Overfilling of.

the tube may cause leakage that leads to production stops or damaging of associated components. As production stops are costly, reducing the risk for damaging of the packaging material during filling and forming of the packaging containers is of significant importance. Even if not causing leakage, overfilling also creates undesired waste of the food product that is filled. It is thus desired to monitor liquid levels in package producing machines.

A package producing machine having a liquid level detector is disclosed in patent document <CIT>.

In light of the observations above, there is thus a need for improved control of the level of liquid content in the tube of packaging material. Hence, the present inventors have identified both the need for and the benefits of a robust and accurate measuring of the level of liquid content.

It is accordingly an object of the invention to solve, eliminate, alleviate, mitigate or reduce at least some of the problems and shortcomings referred to above.

In this disclosure, a solution to the problem outlined above is proposed. In the proposed solution, a level reader device, a level reader system, and a package producing machine is described.

In a first aspect, a level reader system for determining a level of liquid in a tube of packaging material, wherein the level reader system comprises a magnetic float and a level reader device for a package producing machine, is provided.

The level reader device comprises a housing extending in a longitudinal direction being substantially parallel to a filling direction of a tube of packaging material, a plurality of sensors being distributed in the housing along the longitudinal direction and configured to provide one or more sensor readings, and a processing unit being configured to determine a level of liquid in the tube of packaging material based on the one or more sensor readings. The magnetic float comprises a cylinder and a ring-shaped holder arranged in the cylinder, and wherein the ring-shaped holder comprises a plurality of magnets being distributed around said holder.

Benefits of the present invention come from the level reader device being capable of providing extremely accurate liquid level signals due to a very high density of sensors. Moreover, as the total length of the level reader device is substantially larger compared to what is known in the art, maintenance of liquid level control can be performed over a larger space. Hence, the package producing machine becomes more robust and versatile for different package sizes, and the risk of having overfilling of liquid in the machine (and thus stopping of machine production) is vastly minimized. The topology of the plurality of sensors furthermore simplifies the installation of the level reader device, as well as associated components in the package producing machine. Additionally, thanks to improved sensitivity of the plurality of sensors in the level reader device, compatibility is enabled for a variety of associated magnetic devices that are not capable of generating strong magnetic fields. This also results in minimizing the risk of false readings.

According to one embodiment, the plurality of sensors is configured to provide the one or more sensor readings at the same time which are indicative of defined values separated from zero, wherein one sensor reading among the one or more sensor readings is indicative of a value higher than the other sensor readings.

According to one embodiment, the processing unit is configured to determine the level of liquid in the tube of packaging material from said one sensor reading which is indicative of a value higher than the other sensor readings.

According to one embodiment, the sensors of the plurality of sensors are capable of operating individually and different sensors of the plurality of sensors are configured to provide at the same time said plurality of sensors readings.

According to one embodiment, one sensor reading among the one or more sensor readings is indicative of a value lower than the other sensor readings, and the processing unit is configured to determine the level of liquid in the tube of packaging material from an average value of said sensor reading which is indicative of a value higher than the other sensor readings and said sensor reading which is indicative of a value lower than the other sensor readings.

According to one embodiment, the processing unit is configured to determine the level of liquid in the tube of packaging material from a moving average of a predetermined number of previously provided sensor readings.

According to one embodiment, the processing unit is configured to determine the level of liquid in the tube of packaging material by selecting one of: said one sensor reading which is indicative of a higher value than the other sensor readings, said average value, or said moving average.

According to one embodiment, the plurality of sensors is in the range of <NUM> to <NUM> sensors, preferably in the range of <NUM> to <NUM> sensors, and most preferably in the range of <NUM> to <NUM> sensors.

According to one embodiment, the plurality of sensors are distributed along a length of <NUM> to <NUM>, preferably along a length of <NUM> to <NUM>, and most preferably along a length of <NUM> to <NUM>.

According to one embodiment, each of the plurality of sensors is a magnetoresistive sensor.

According to one embodiment, the magnetoresistive sensitivity of each sensor is in the range of <NUM> to <NUM>, preferably in the range of <NUM> to <NUM>.

According to one embodiment, the longitudinal extension of the housing is substantially larger than a vertical extension of the ring-shaped holder.

In a second aspect, a package producing machine is provided. The package producing machine comprises the level reader system according to the first aspect and any of the embodiments associated therewith.

It should be emphasized that the term "comprises/comprising" when used in this specification is taken to specify the presence of stated features, integers, steps, or components, but does not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof. All terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the [element, device, component, means, step, etc]" are to be interpreted openly as referring to at least one instance of the element, device, component, means, step, etc., unless explicitly stated otherwise.

The drawings are not necessarily to scale; emphasis is instead placed upon illustrating the example embodiments.

Embodiments of the invention will now be described with reference to the accompanying drawings. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The terminology used in the detailed description of the particular embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention.

With reference to <FIG>, a package producing machine <NUM> according to one embodiment is illustrated. The illustrated package producing machine <NUM> can be used in the food packaging industry for creating package containers <NUM> filled with liquid food, such as milk, mineral water, tea, juice, soup, drinks, or the like. Production of a packaging container <NUM> involves multiple steps, processes or techniques, some of which are shown in <FIG>. The illustrative image is not to be interpreted as limiting to the scope of this disclosure, as it merely shows one possible embodiment of the package producing machine <NUM> as disclosed herein. The package producing machine <NUM> may comprise any number of additional or fewer steps, processes or techniques, provided that the inventive aspects of the present disclosure are enabled.

In <FIG>, a web of packaging material <NUM> is, for instance, provided on a reel <NUM>, and fed continuously through the package producing machine <NUM> where it passes several different stations in motion. <FIG> specifically depicts an aseptic chamber <NUM>, a filling station <NUM>, and a sealing and forming station <NUM>, although other relevant stations can also be realized.

The web of packaging material <NUM> enters the aseptic chamber <NUM> and passes a sterilization unit <NUM> in the form of one or more electron beam emitters <NUM>. After being exposed to electron beam irradiation, the web of packaging material <NUM> exits the aseptic chamber <NUM>. It should be noted that the sterilization unit <NUM> may not necessarily be based on electron beam irradiation, as other sterilization techniques such as H<NUM>O<NUM> may be used as well.

In the filling station <NUM>, the web of packaging material <NUM> is formed into a tube of packaging material <NUM>, hereinafter simply being referred to as a "tube". The tube <NUM> is filled with the desired liquid content, preferably a liquid food product, through a filling pipe <NUM>. The filling station <NUM> comprises a level reader system <NUM> that is configured to monitor the amount of liquid content in the tube <NUM>, which will be described in more detail with reference to the remaining figures of this disclosure.

Downstream the filling station <NUM> the sealing and forming section <NUM> is provided. The sealing and forming section <NUM> is configured to provide transversal seals to the tube <NUM>, cut the leading part of the tube <NUM> from the upstream tube <NUM> at the position of the transversal seal, and form the separated package container <NUM> to its desired shape. A plurality of sealing jaws (not shown) may be provided, which are configured to provide transversal seals to the tube <NUM> by engagement with the tube <NUM>. These transversal seals may be formed by e.g. inductive heating which means that the sealing jaws may have to engage the tube <NUM> for a period of time in order to form a high quality transversal seal. The tube <NUM> is then cut into packaging containers <NUM> along the transversal seals by a cutting means.

The processes performed at the sealing and forming section <NUM> typically affect a level <NUM> of liquid in the tube <NUM>. For instance, whenever the tube <NUM> is provided with its transversal seals, the contact caused by applying the sealing jaws will reduce the total volume of the space within the tube <NUM>. Thus the level <NUM> of the liquid in the tube <NUM> will be raised. The volume inside the tube <NUM> will also be affected by the shape of the tube <NUM>; since the forming section <NUM> will normally shape the tube <NUM> from a circular cross-section to a rectangular cross-section, the area enclosed by the tube <NUM> will decrease. As is understood from above, the repetitive action of the sealing and forming section <NUM> will cause variations of the level <NUM> of liquid in the tube <NUM>. Additionally, the energy generated by providing transversal seals to the tube <NUM> using e.g. inductive heating may affect the kinetic energy and consequently the level <NUM> of liquid in the tube <NUM> as well. It is difficult to determine exactly how much the level <NUM> of the liquid in the packaging material will change, as there are many different additional situations that may occur, including but not limited to external affects, production changes, material choices, to name a few. The skilled person may realize additional such situations.

It is particularly difficult to control the level <NUM> of liquid in high-performing package producing machines <NUM> that are capable of producing a significant number of packaging containers <NUM> every second. If the level <NUM> of liquid in the tube <NUM> is not controlled accurately, problems such as the ones presented in the background section may be introduced. It is hence of paramount importance that the level reader system <NUM> is able to provide extremely accurate readings of the level <NUM> of liquid in the tube <NUM>.

Turning now to <FIG>, an embodiment of the level reader system <NUM> is shown.

According to the invention, the level reader system <NUM> comprises a level reader device <NUM> and a magnetic float <NUM> (see also <FIG>). In <FIG>, the squares having dashed lines are indicative of features having more of an optional character, but are nonetheless comprised in a preferred embodiment of the invention. The skilled person may realize additional embodiments for these features in order to enable accurate monitoring of the level <NUM> of liquid in the tube <NUM>.

The magnetic float <NUM> may be arranged inside or within the tube <NUM> so that at least one part of the magnetic float <NUM> is capable of floating on the surface of the liquid within the tube <NUM>. This is visualized in <FIG>. The at least one part of the magnetic float <NUM> is capable of floating both in high and low density liquids. The magnetic float <NUM> may comprise one or more buoyant materials. In different embodiments of the invention, the magnetic float <NUM> may comprise different buoyant materials, and it can be replaced if desired. Desired characteristics of the buoyant materials may include excellent buoyancy, high strength-to-weight ratio, large operational temperature spans, high pressure resistance, etc..

The magnetic float <NUM> is not restricted to having a particular shape, form or dimension, provided that it can fit within the tube <NUM> and perform its intended function, which now will be described.

As is seen in <FIG>, the magnetic float <NUM> comprises a cylinder <NUM> and a ring-shaped holder <NUM> arranged in the cylinder <NUM>. The cylinder <NUM> is preferably arranged around an outer circumference of the filling pipe <NUM>, although alternative arrangements may be realized. The filling pipe <NUM> is fixedly arranged within the tube <NUM>, and provided so that a filling direction <NUM> is enabled in a substantially vertical direction along a vertical axis in relation to the ground. Hence, the cylinder <NUM> is configured to be movable in the filling direction <NUM>, along the filling pipe <NUM>. The magnetic float <NUM> floats on the liquid within the tube <NUM>, and movement of the cylinder <NUM> is thereby enabled by a raising movement or a sinking movement of the magnetic float <NUM> as caused by the level <NUM> of the liquid in the tube <NUM>. The magnetic float <NUM> may be arranged so that it can freely rotate around filling pipe <NUM>. This is particularly beneficial, since it minimizes or even eliminates the risk of the level reader device <NUM> not being able to pick up magnetic signals or magnetic fields as generated by the magnetic float <NUM>.

As indicated in <FIG>, the cylinder <NUM> comprises a ring-shaped holder <NUM>. According to the invention, the ring-shaped holder <NUM> is arranged in the cylinder <NUM>. The ring-shaped holder <NUM> comprises a plurality of magnets <NUM> being distributed, arranged or held around the holder <NUM>. <FIG> illustrates in more detail how the plurality of magnets <NUM> may be distributed around the ring-shaped holder <NUM>. In this example, a total of <NUM> magnets are arranged around the holder <NUM>. The number of magnets within the magnetic float <NUM> may vary, depending on e.g. dimensions, materials, or other characteristics of the magnetic float <NUM>, filling pipe <NUM> and/or magnetic reader <NUM>.

In alternative embodiments not encompassed by the wording of the claims, the plurality of magnets <NUM> may be arranged on either one of the magnetic float <NUM> or the cylinder <NUM>, without requiring the assistance of a ring-shaped holder <NUM> and/or the cylinder <NUM>.

As the magnetic float <NUM> moves along the filling direction <NUM> and possibly rotates around the filling pipe <NUM>, the plurality of magnets <NUM> are configured to continuously generate magnetic signals or magnetic fields. The level reader device <NUM> is configured to read these signals in order to determine the current level <NUM> of liquid in the tube <NUM>.

Now turning to <FIG> illustrating a level reader system <NUM> according to one embodiment. With reference to these figures, the level reader device <NUM> will be described more thoroughly. The level reader device <NUM> comprises a housing <NUM>, a plurality of sensors <NUM>, and a processing unit <NUM>.

In different embodiments of the level reader device <NUM>, the housing <NUM> is shaped, sized, formed and/or dimensioned in any suitable manner. Suitable in this regard means that the housing <NUM> is adapted to be arranged in the package producing machine <NUM> and house the components of the level reader device <NUM>. The housing <NUM> is extending in a longitudinal direction being substantially parallel to the filling direction <NUM> of the tube <NUM>, which can be seen in <FIG>. The housing <NUM> may have an elongated shape that is extending in the longitudinal direction. The housing <NUM> is preferably arranged in proximity to the tube <NUM>, and thereby the magnetic float <NUM>, such that the magnetic signals or magnetic fields generated from the magnetic float <NUM> can be read by the level reader device <NUM> even when the tube <NUM> is arranged between the level reader device <NUM> and the magnetic float <NUM>.

The plurality of sensors <NUM> are distributed in the housing <NUM>, along the longitudinal direction, and configured to provide one or more sensor readings <NUM>. Preferably, the plurality of sensors <NUM> are distributed along the extending edge of the housing <NUM> that is facing towards the magnetic float <NUM>, such that the one or more sensor readings <NUM> can be provided more accurately. Alternatively, the plurality of sensors <NUM> may be distributed anywhere within the housing <NUM>, given that the sensor readings <NUM> can be provided accurately.

The plurality of sensors <NUM> may be an arbitrary number of sensors that can fit within the housing <NUM>. In one embodiment, the plurality of sensors <NUM> is in the range of <NUM> to <NUM> sensors. In a more preferred embodiment, the plurality of sensors <NUM> is in the range of <NUM> to <NUM> sensors. In a most preferable embodiment, the plurality of sensors <NUM> is in the range of <NUM> to <NUM> sensors. The plurality of sensors is distributed along a specific length that generally corresponds to a length of the longitudinally extending side of housing. In one embodiment, the length is anywhere between <NUM> to <NUM>. In a more preferred embodiment, the length is between <NUM> to <NUM>. In a most preferred embodiment, the length is between <NUM> to <NUM>.

The plurality of sensors <NUM> may be magnetoresistive sensors commonly known in the art. Magnetoresistive sensors are ultra-sensitive devices that are designed to be durable and reliable speed or position sensors for small magnetic fields in power applications. The supply voltage range for such applications may be in the range of <NUM> Vdc to <NUM> Vdc, and typically around <NUM> Vdc. The temperature range of the magnetoresistive sensors may be in the temperature range -<NUM> to <NUM>. The magnetoresistive sensors do not require identification of the magnet polarity, which simplifies the installation process and potentially reduces the system cost. Benefits provided by the magnetoresistive sensors include, for instance, durability and reliability due to a magnetic solid state, non-contact and no-glass design, and cost-efficiency and flexibility due to ultrahigh sensitivity.

The magnetoresistive sensitivity of the plurality of sensors <NUM> may be a value typical for such magnetoresistive sensors. In one embodiment, the magnetoresistive sensitivity is in the range of <NUM> to <NUM>. The magnetoresistive sensors may be based on two different types of sensors. In the first one of these types, the magnetoresistive sensitivity is in the range of <NUM> to <NUM>, wherein <NUM> is the typical operation sensitivity and <NUM> is the maximum operation sensitivity. In the second one of these types, the magnetoresistive sensitivity is in the range of <NUM> to <NUM>, wherein <NUM> is the typical operation sensitivity and <NUM> is the maximum operation sensitivity. Any one or a combination of these two types may be used for the magnetic float <NUM>. Provided with the magnetoresistive sensors having a higher magnetoresistive sensitivity, according to this description, it is possible to arrange the level reader device <NUM> further away from the magnetic float <NUM> than what was previously possible, which may simplify the installation and operation processes.

The processing unit <NUM> may be arranged as a single unit or as several controllers that are collectively configured to perform the operations of the processing unit <NUM>. The processing unit <NUM> may be implemented in any known controller technology, including but not limited to microcontroller, processor (e.g. PLC, CPU, DSP), FPGA, ASIC or any other suitable digital and/or analog circuitry capable of performing the intended functionality. The processing unit <NUM> may comprise a memory. The memory of the processing unit <NUM> may be implemented in any known memory technology, including but not limited to ROM, RAM, SRAM, DRAM, CMOS, FLASH, DDR, SDRAM or some other memory technology. In some embodiments, the memory may be integrated with or be internal to the processing unit <NUM>.

The processing unit <NUM> is configured to receive, analyze, and make a decision based on the provided one or more signal readings <NUM> from the plurality of sensors <NUM>. The decision is related to determining the level <NUM> of liquid in the tube <NUM>.

In one embodiment, the processing unit <NUM> is arranged within the housing <NUM>. Alternatively, the processing unit <NUM> is arranged as an external unit that is in wired and/or wireless communication with the level reader device <NUM>. In either one of these two embodiments, the processing unit <NUM> is arranged so that a decision regarding the level <NUM> of liquid in the tube <NUM> can be generated in a very short time. In preferred embodiments, the time required to provide signal readings <NUM>, analyze the signal readings <NUM>, and accurately determine the level <NUM> of liquid in the tube <NUM>, is less than <NUM>.

If the processing unit <NUM> is arranged as an external unit being in wireless communication with the level reader device <NUM>, the level reader device <NUM> may further comprise any communication means known in the art for enabling said communication. Such communication means may be based on short-range communication technologies such as e.g. WiFi or Bluetooth.

Regardless of where the processing unit <NUM> is arranged, the decision may be used to control the operation of the package producing machine <NUM> in general, and the operation of the filling pipe <NUM> in particular. For instance, the decision may be used to control the discharge flow of liquids as outputted from the filling pipe <NUM>, the operation speed of the package producing machine <NUM>, or any similar control operations realized by the person skilled in the arts. Such operations are preferably automatically controlled.

In <FIG>, one embodiment of a level reader device <NUM> is shown. This particular level reader device <NUM> comprises <NUM> sensors, wherein each one is individually configured to provide a sensor reading <NUM>. As the plurality of sensors <NUM> are capable of operating individually, the one or more sensor readings <NUM> may be provided at the same time from different sensors <NUM>. The sensor readings <NUM> are indicative of defined values that are separated from zero. "Defined" is in this sense referring to a correctly read signal that is indicative of a value, i.e. not being an erroneous reading. Hence, the sensor readings <NUM> are indicative of a magnetic object, such as the magnetic float <NUM>, being sufficiently close to the plurality of sensors <NUM> in order to identify magnetic signals. Since the one or more sensor readings <NUM> can be provided at the same time, and since each individual sensor of the plurality of sensors <NUM> are arranged at different locations along a side of the housing <NUM> and are providing readings <NUM> of the same magnetic object, the values will typically differ from one another depending e.g. on the actual distance between the specific sensor <NUM> and the magnetic float <NUM>.

In the particular example illustrated in <FIG>, a total of <NUM> sensor readings <NUM> have been read at the same time, each one being indicative of a defined value that is separated from zero. For the sake of simplicity, the values are in the figure denoted as positive integer values ranging from '<NUM>' to '<NUM>'. For an actual level reader device <NUM>, however, may these values assume any appropriate value. As can be seen, the sensors <NUM> that are closer to the magnetic float <NUM> are providing sensor readings <NUM> that are indicative values that are higher than the sensors <NUM> that are farther away from the magnetic float <NUM>.

As can be seen in <FIG>, one sensor reading <NUM> among the one or more sensor readings <NUM> is indicative of a value that is higher than the other identified readings. In the exemplifying picture, this value is a '<NUM>'. In the case where one sensor reading is indicative of a value that is exactly the same as the value of another sensor reading, either one or both of these two values may be identified as the one sensor reading <NUM> being indicative of a value that is higher than the values of the other readings. The processing unit <NUM> may thus be configured to determine the level <NUM> of liquid in the tube <NUM> from the one sensor reading <NUM> being indicative of the value that is higher than the values of the other sensor readings.

In an alternative embodiment, one sensor reading <NUM> among the one or more sensor readings <NUM> is indicative of a value lower than the other sensor readings. In <FIG>, this value is a '<NUM>', which can be seen at a defined reading <NUM> as provided from two separate sensors <NUM> that are farthest away from the magnetic float <NUM>. The processing unit <NUM> may be configured to determine the level <NUM> of liquid in the tube <NUM> from an average value 65a of said sensor reading <NUM> being indicative of a value higher than the other sensor readings, and the sensor reading <NUM> being indicative of a value lower than the other sensor readings.

In yet an alternative embodiment, the processing unit <NUM> is configured to determine the level <NUM> of liquid in the tube <NUM> from a moving average 65ma of a predetermined number of previously provided sensor readings <NUM>. In one embodiment, the predetermined number is a total number for all of the sensors <NUM> together. In another embodiment, the predetermined number is a number for an individual sensor <NUM>. Typically, the number of previously provided sensor readings may be <NUM> readings, but the number can also be fewer or more, or be varying during operation. Determining the level <NUM> of liquid in the tube <NUM> from a moving average 65ma may be particularly useful in case of a sudden drop or rise of the level <NUM> of liquid, or to handle erroneous readings <NUM> provided by e.g. defective sensors <NUM>.

The processing unit <NUM> may in one embodiment be configured to determine the level <NUM> of liquid in the tube <NUM> by selecting either one of the sensor reading <NUM> being indicative of a higher value than the other sensor readings, the average value 65a, or the moving average 65ma. This selection may be automatically controlled by the processing unit <NUM>, or manually controlled by an operator or technician. The selection may be based on a variety of different factors, such as e.g. what liquids, components, materials or operational settings are used. The processing unit <NUM> may be configured to intelligently generate the decision based on the sensor readings <NUM>, by e.g. analyzing previously acquired data for current operational settings. Such intelligent decisions may be generated by a self-learning algorithm that is implementing any known supervised and/or unsupervised learning algorithms, such as e.g. example regression algorithms, decision trees, K-means, K-nearest neighbours, neural networks, support vector machines or principal component analysis.

<FIG> illustrate schematic illustrations of the level reader device <NUM> generally in accordance with the present disclosure.

In <FIG>, the level reader device <NUM> can be seen in an arrangement with the magnetic float <NUM>, i.e. a level reader system <NUM>. In a preferred embodiment, which is illustrated in <FIG>, the longitudinal extension of the level device reader <NUM> is substantially larger than a vertical extension of the magnetic float <NUM>. Particularly, the longitudinal extension of the housing <NUM> is substantially larger than the vertical extension of the ring-shaped holder <NUM>. This allows for a very robust filling system, as the ring-shaped holder <NUM> that is holding the plurality of magnets <NUM> may travel a distance that is several times longer than its own vertical extension, and still be correctly identified by the level reader device <NUM>. The length ratio between the housing <NUM> and the vertical extension of the ring-shaped holder <NUM> may be similar to the length ratio as depicted in <FIG>. Other length ratios may also be realized.

<FIG> further depicts fastening means <NUM> that is adapted to fasten the level reader device <NUM> to the other components of the package producing machine <NUM>. The fastening means <NUM> is in this example provided as an arm that is fixedly attached to the package producing machine <NUM>. In other embodiments, the fastening means <NUM> may be any structure that is suitably mounted to the package producing machine using any one or a combination of screws, bolts and/or adhesive materials. As the level reader device <NUM> is securely fixed and kept stationary during operation, its position may be calibrated and set e.g. in relation to downstream sealing jaws; by associating the read indicative value <NUM>, as explained above, to the respective sensor <NUM>, it is possible to convert the actual sensor to a height above the sealing jaws. Hence, the monitored level of product in the tube <NUM> may easily be converted to a tube filling height in centimeters or millimeters.

<FIG> is a schematic illustration of a level reader device <NUM> according to a preferred embodiment, and <FIG> is an enlarged section of <FIG>. The illustrative images generally show how the housing <NUM>, the plurality of sensors <NUM>, and the processing unit <NUM> may be arranged within the level reader device <NUM>.

Claim 1:
Level reader system (<NUM>) for determining a level (<NUM>) of liquid in a tube of packaging material (<NUM>), wherein the level reader system (<NUM>) comprises a magnetic float (<NUM>) and a level reader device (<NUM>) for a package producing machine,
wherein the level reader device (<NUM>) comprises:
a housing (<NUM>) extending in a longitudinal direction being substantially parallel to a filling direction (<NUM>) of a tube of packaging material (<NUM>);
characterized in that the level reader device (<NUM>) further comprises
a plurality of sensors (<NUM>) being distributed in the housing (<NUM>) along the longitudinal direction and configured to provide a plurality of sensor readings (<NUM>); and
a processing unit (<NUM>) being configured to determine a level (<NUM>) of liquid in the tube of packaging material (<NUM>) based on the plurality of sensor readings (<NUM>),
wherein the magnetic float (<NUM>) comprises a cylinder (<NUM>) and a ring-shaped holder (<NUM>) arranged in the cylinder (<NUM>), and wherein the ring-shaped holder (<NUM>) comprises a plurality of magnets (<NUM>) being distributed around said holder (<NUM>).