EP3263471B1 - Label sensor for scanning labels on a carrier strip - Google Patents

Description

The invention relates to a label sensor for scanning labels on a carrier tape, with a sensor body, with a ferromagnetic core with a coil, and with a scanning element.

To apply labels to objects to be labeled, the labels are usually detached from a label tape and applied to the object in an adhesive manner. This process is usually also referred to as label dispensing and is carried out by means of labeling machines that drive a label strip provided with labels. The labeling machines also have at least one label sensor which is arranged on the label strip and which continuously checks whether a label is present at a certain point on the label strip. If this is the case, the labeling machine stops the drive of the label tape for a short time in order to print and / or transfer the label. The label tape is then accelerated again until the label sensor detects a label again.

In order to make optimal use of the area of the label tape, the labels on the tape are attached to the tape at small intervals, usually 2 mm to 4 mm. The efficiency of the labeling process is therefore largely determined by the time in which labels can be detected and applied.

Label sensors according to the preamble of claim 1 are for example from DE 20 2014 101 101 U1 known, which have a sensor head, two electrically conductive spring elements and a fastening part. The sensor head is provided with an electromagnet, which has a ferromagnetic core and a coil, and whose signal is used for label detection. The attachment part is used to attach the label sensor to the labeling machine.

When used, the known label sensor is arranged in the vicinity of the label tape in such a way that its sensor head is in contact with the label tape. The sensor head of the label sensor is designed to be elastic due to the electrically conductive spring elements. An electrically conductive part, including a ferromagnetic part, such as a stainless steel sheet, is arranged on the opposite side of the label tape.

The sensor head changes its distance from the label tape depending on whether or not there is a label between the sensor head and the label tape. This changed distance causes a change in the magnetic field between the electromagnet formed with the sensor coil and the opposite ferromagnetic part and is thus expressed in a changed electrical signal the coil of the sensor head, which is measured and evaluated by means of an electrical measuring unit. It can thus be determined when exactly a label is present on the label tape, so that the label tape can then be stopped and the label can be applied to the object.

The known label sensors have the disadvantage that, in particular for the production of the sensor body, a plurality of different components made of different materials are always necessary, which are connected to one another.

This not only requires a design effort, but also a cost. In addition, problems arise with regard to the fastening of the materials of the sensor body to one another and with regard to the durability of the electrical connections of the components of the sensor body.

It is therefore the object of the invention to eliminate the disadvantages mentioned and to develop a label sensor that is easier to manufacture and offers reliable and diverse electrical connection options.

The object is achieved by means of a label sensor with the features of independent claim 1, which is characterized in that the sensor body is designed as a printed circuit board with at least one electrically insulating carrier layer and at least one conductor plane with electrical conductors arranged on the carrier layer and that a central connection area of the Sensor body has a lower strength or weakening compared to the two-sided adjoining contact and sensor areas.

The entire sensor body, which is designed as a printed circuit board, is thus in one piece, i.e. designed as a part that cannot be separated without destruction. At one end it has a contact area and at the other end a sensor area carrying the actual sensor and, between this, a connecting area with a low thickness, which is thus designed to be elastic.

The invention is based on the consideration that the design of the sensor head as a printed circuit board eliminates the need for the discrete components of the sensor body known from the prior art, such as in particular the spring elements and the fastening part mentioned in this context. Instead, both the properties of the circuit board with regard to its elasticity and with regard to the electrical connection options can be used. This eliminates the disadvantages known from the prior art. In addition, the components required for the label sensor can be designed as integrated components on the circuit board, which manifests itself in a space-saving design of the label sensor.

The carrier layer of the circuit board is electrically insulating, i.e. non-conductive, and preferably has at least partially a component made of a composite material, in particular a glass fiber composite material, a composite material made of glass fibers and an epoxy resin being most preferably provided. For example, the material FR4, which is widely used for printed circuit boards, can be provided for the carrier layer, such as Isola IS 410 from Isola GmbH. As a component of the label sensor, the sensor body thus has sufficiently flexible material properties for the application. In particular, there is also no need for additional spring elements.

As an alternative or in addition to this, the carrier layer of the printed circuit board can have components made of polymers, polyesters, in particular foils made of polyamide, Teflon, aluminum oxide, PET, PEN or ceramic. In a special case, the carrier layer of the circuit board consists of a flexible polyamide film that has elastic properties.

Flexibility within the meaning of the invention refers to the ability of a body to change its shape due to an externally acting force. Elastic in the context of the invention means that a body deformed by an external force generates a restoring force due to the deformation in order to return to the original state when the load is removed. This restoring force can in particular be proportional to the deformation of the body, for example in the case of a spring.

The conductor plane of the sensor body has at least one electrical conductor, which is preferably designed as a conductor track made of copper. The at least one conductor track of the conductor plane can be produced, for example, by means of an etching process, starting from an originally flat conductor layer. The remaining area of the conductor plane that is not provided with the conductor track is provided with an electrically insulating material, such as an epoxy resin.

In an advantageous embodiment of the sensor body as a printed circuit board, the carrier layer has both on one Both the top and the bottom each have a conductor level. This offers greater freedom for the electrical connections. The spatially separated conductor planes on the top and bottom of the carrier layer are electrically insulated from one another by the carrier layer, but can be electrically connected to one another by means of at least one VIA. A VIA in the sense of the invention denotes an opening in the carrier layer and possibly in the conductor plane, which is provided with electrically conductive material and thereby enables an electrical connection of several conductor planes.

The circuit board preferably has at least one board layer. A board layer in the sense of the invention denotes a layer composite of a carrier layer and at least one additional layer, wherein preferably two additional layers, one of the additional layers on an upper side of the carrier layer and the other of the additional layers can be arranged on an underside of the carrier layer. These additional layers are preferably designed as conductor planes, but the layers can also have other materials and take on other functions, which is described in detail below. Conductor tracks of conductor levels of different plate layers can be electrically connected to one another, preferably by means of at least one VIA.

In a further advantageous embodiment, the conductor track of at least one conductor layer of the sensor body is provided with a protective layer, the protective layer in particular consisting of a compound of nickel and gold, which is also known as "chemical nickel gold" (NiAu). The protective layer made of NiAu serves on the one hand as oxidation protection (Au) and on the other hand as a solder bridge (Ni) for additional components for the sensor body.

According to the invention, a central connection area of the sensor body has a lesser thickness or weakening or depression than in the contact and sensor areas adjoining on both sides, as a result of which the elastic properties of the sensor body are improved. In particular, the weakening of the sensor body creates a larger swivel radius of the flexible sensor body. On the one hand, this configuration increases the scope of application of the label sensor and, on the other hand, increases its longevity. The central connection area with the weakening thus forms a resilient element of the sensor body.

The recess of the sensor body in the middle area can be milled and is therefore easy to manufacture. In addition, the recess can be punched out or manufactured by laser processing.

In a further advantageous embodiment of the invention, the sensor body is designed as a multilayer printed circuit board with at least one prepreg layer. In the context of the invention, a prepreg layer denotes a finished part, namely a layer made of a semifinished product called prepreg, which has not yet cured, made of a resin and a carrier material. The same materials are used as the carrier material as for the carrier layer. For example, the prepreg layer can be provided between two panel layers. Since the prepreg layer has not yet hardened, parts of the prepreg semi-finished product get into any existing, small recesses in the panel layers surrounding the prepreg layer. To cure the prepreg layer, it is pressed with the surrounding board layers with the addition of heat, so that after the prepreg layer has hardened, the two board layers are bonded to one another due to the original flow properties of the prepreg layer.

The prepreg layer is most preferably designed as a no-flow prepreg layer. A no-flow prepreg layer refers to a prepreg layer that has a particularly high viscosity during the curing process, so that the no-flow prepreg layer retains its shape during the curing process and hardly changes its structure so that its dimensional accuracy is retained. This creates a particularly dimensionally stable connection between two panel layers. It is possible to introduce contours, for example punched out or generated by means of laser cutting, into the no-flow prepreg layer and to keep these contours dimensionally stable even after the curing process.

During production, the no-flow prepreg layer is only applied in the end areas of the sensor, leaving the area of the later lower strength or weakening free. The further layering takes place through hardened plate layers. To produce the area of lesser thickness or weakening, these layers located above the no-flow prepreg layer are then removed, in particular by piercing. It has been shown that this makes it possible to produce a sensor carrier that is significantly more reproducible and with lower tolerances than by Milling (out) of the weakening is already possible. In particular, very precisely reproducible parts can be achieved to some extent as a result.

The no-flow prepreg layer, in conjunction with the recess in the middle connection area of the sensor body, minimizes the risk that parts of the no-flow prepreg layer will get into the area of the recess or later weakening and the structure of the Adversely affect printed circuit board. As a result, the defined shape of the depression or weakening is retained even after the curing process, and the mechanical properties of the sensor body can thus be precisely defined.

In addition to or as an alternative to the recess, the central connecting area of the sensor body can be provided with at least one longitudinal opening in order to improve the elastic properties of the sensor body.

An underside of the sensor body facing away from the sensing element can at least partially be provided with a plastic coating, which preferably consists of a polyamide, in particular nylon or Teflon. Particularly in combination with the design of the carrier layer as a film, for example made of polyamide, PET or PEN, on which a conductor layer can also be arranged on one or both sides, the stiffness of the sensor body and thus its elastic properties are influenced by the coating.

In an alternative embodiment of the invention it can be provided that the coil is designed as a conductor track or as a winding made of wire.

In the first embodiment, there is no need for coils in the form of a winding as a separate component for the label sensor, so that rather the coil is designed as an integrated component, namely a spiral-shaped conductor track in the sensor body.

Such coil tracks are preferably provided in several conductor planes of the sensor body, so that a significantly higher number of turns and thus a greater inductance can be achieved in connection with the core of the label sensor. Most preferably, a winding is provided in each of the conductor levels. Several coil tracks can be electrically connected to one another by means of at least one VIA.

It is preferably provided that the ferromagnetic core has concentric inner and outer annular projections, between which an annular groove for receiving the coil is formed.

One embodiment provides that the outer ring projection has openings in the longitudinal direction of the label sensor.

In a further advantageous development, the sensor body has an ESD protective structure for protection against, in particular, electrostatic discharges. Similar to a lightning conductor, the ESD protective structure serves to dissipate static charges, preferably via an earthed electrical connection provided on the sensor body. This avoids damage to the sensor body due to electrical discharges.

The ESD protective structure is preferably formed in a conductor plane of the sensor body, in particular as at least one protective line. For example, the protective line is connected to all integrated components of the sensor body. In the case of several spatially separated conductor levels, individual or all conductor levels can have protective lines. These can be electrically connected to one another, for example by means of at least one VIA.

The sensor body can have at least one temperature-dependent resistor, to which at least one capacitor connected in parallel can preferably be assigned. By means of a measuring device, a parameter correlating to the ambient temperature can be measured on the temperature-dependent resistance, for example the temperature-dependent resistance itself and / or the voltage drop resulting from the temperature-dependent resistance. The ambient temperature can be determined indirectly via this temperature-dependent parameter. Depending on the ambient temperature, in particular the inductance of the electromagnet made up of the core and coil can change, which leads to a falsification of the measurement results. By detecting the ambient temperature through the temperature-dependent resistor, a corresponding correction can be made on the software side. This makes the measurements less sensitive to fluctuations in the ambient temperature.

The temperature-dependent resistor is preferably attached to the side of the printed circuit board facing the carrier tape so that no heating effects of the sensor itself impair the measurement.

The temperature-dependent resistor can preferably be attached, in particular soldered, to the top of a conductor layer of the sensor body. This design as an SMD (surface mounted device) eliminates the need for bores in the sensor body for fastening the temperature-dependent resistor.

Fig. 1a

einen Etikettensensor in perspektivischer Sicht von schräg oben,;

Fig. 1b

den Etikettensensor von Fig. 1a in Aufsicht;

Fig. 1c

den Etikettensensor von Fig. 1b im Schnitt durch die Schnittlinie A-A;

Fig. 2a bis 2c

eine weitere Ausgestaltung des Etikettensensors gemäß den Darstellungen der Fig. 1a bis 1c;

Fig. 3a bis 3c

eine weitere Ausgestaltung des Etikettensensors gemäß den Darstellungen der Fig. 1a bis 1c;

Fig. 4

einen schematischen Aufbau eines Sensorköpers mit mehreren Plattenlagen im Schnitt;

Fig. 5

einen weiteren schematischen Aufbau eines Sensorkörpers mit einer zusätzlichen Polyamidschicht;

Fig. 6

eine weitere Ausgestaltung des Sensorkörpers;

Fig. 7

den Sensorkörper von Fig. 6 mit zusätzlichem Abtastglied und einer Abschirmung;

Fig. 8

eine weitere Ausgestaltung des Sensorkörpers mit einer mehrlagigen Leiterplatte in Aufsicht mit besonderer Hervorhebung der elektrischen Kontaktierungen;

Fig. 9

eine Aufsicht auf eine obere Leiterschicht des Etikettensensors aus Fig. 8;

Fig. 10

eine Aufsicht auf eine mittlere Leiterschicht des Etikettensensors aus Fig. 8;

Fig. 11

eine Aufsicht auf eine untere Leiterschicht des Etikettensensors aus Fig. 8 und

Fig. 12

einen elektrischen Schaltplan für den Sensorkörper aus Fig. 8 bis 11.

Further advantages and features of the invention emerge from the claims and from the following description, in which exemplary embodiments of the invention are explained in detail with reference to the figures. Show:

Fig. 1a

a label sensor in a perspective view obliquely from above;

Figure 1b

the label sensor from Fig. 1a under supervision;

Figure 1c

the label sensor from Figure 1b in section through the section line AA;

Figures 2a to 2c

a further embodiment of the label sensor according to the representations of FIG Figures 1a to 1c ;

Figures 3a to 3c

a further embodiment of the label sensor according to the representations of FIG Figures 1a to 1c ;

Fig. 4

a schematic structure of a sensor body with several plate layers in section;

Fig. 5

a further schematic structure of a sensor body with an additional polyamide layer;

Fig. 6

another embodiment of the sensor body;

Fig. 7

the sensor body of Fig. 6 with additional sensing element and a shield;

Fig. 8

a further embodiment of the sensor body with a multilayer printed circuit board in a plan view with special emphasis on the electrical contacts;

Fig. 9

a plan view of an upper conductor layer of the label sensor Fig. 8 ;

Fig. 10

a plan view of a middle conductor layer of the label sensor Fig. 8 ;

Fig. 11

a plan view of a lower conductor layer of the label sensor Fig. 8 and

Fig. 12

an electrical schematic for the sensor body Figures 8-11 .

Figure 1a shows a label sensor 1 according to the invention with a sensor body 2 in a perspective view obliquely from above.

The sensor body 2 can be roughly divided into three areas, a front, in Figure 1a contact area 3 shown on the left, a middle connection area 4 and a rear, in Figure 1a Sensor area shown on the right 5.

The sensor body 2 is designed as a printed circuit board, the structure of which is described in detail below. Due to the configuration according to the invention, the sensor body 2 is elastic in such a way that the rear sensor area 5 can be deflected with respect to the front contact area 3, this causing a restoring force directed against the deflection.

In the following, a “front” direction denotes a direction that faces the front contact area 3, while a “rear” direction faces the rear sensor area 5.

The front contact area 3 has an essentially rectangular base area, with those sides that run parallel to a longitudinal direction L of the label sensor 1 each being provided with a funnel-shaped recess 6 with concavely curved walls, by means of which the label sensor 1 is positively connected to a Labeling machine can be attached, for example by clamping action.

On the two rear edges of the front contact area 3 facing the middle connection area 4, two cylindrical shoulders 7 are additionally formed.

In the front part of the front contact area 3, five circular and continuous contact bores 8 arranged next to one another are formed transversely to the longitudinal direction L of the label sensor 1. The contact bores 8 are used for the electrical and mechanical connection of the sensor body 2 to an electrical contact part 9 which, in the exemplary embodiment shown, has three contact pins 10 on its upper side facing the label sensor 1, which are shown in FIG Fig. 1a are covered in perspective by the sensor body 2 and in section of the Fig. 3 can be seen. The contact pins 10 of the contact part 9 reach through the contact bores 8 of the front contact area 3 in such a way that the contact pins 10 are flush with an upper side 11 of the front contact area 3. The electrical contact part 9 itself is arranged on an underside 12 of the sensor body 2. The contact pins 10 form three contact feet 13 on the underside of the contact part 9 facing away from the sensor body 2, via which the label sensor 1 can be electrically connected to a higher-level circuit of the labeling machine.

The front contact area 3 has, on its side facing the central connecting area 4, a circular fastening bore 22, which is designed as a breakthrough and by means of which the label sensor 1 can be fastened to the labeling machine, for example by means of a bolt, a screw or the like. For this purpose, the fastening bore 22 can have a thread (not shown).

In this exemplary embodiment, the central connecting area 4 of the sensor body 2 is less thick than the areas 3, 5, so that a weakening 14 or a Recess is formed. The recess 14 can be formed by milling in the sensor body 2.

Alternatively, in the manufacturing process, no-flow prepreg applied in the end areas, leaving the late area of reduced thickness exposed, and subsequent removal of through-hardened plate layers, depressions 14 or areas of lesser thickness, formed by piercing, can be produced. The areas 3, 5 protrude more than half of the middle connection area 4 in the direction perpendicular to the direction of extension of the sensor 1, so that the material thickness of the sensor body 2 in the middle connection area 4 is considerably reduced.

The already mentioned flexible and elastic properties of the sensor body 2 are improved by the weakening 14 of the central connecting area 4. In the context of the invention, “flexible” means that the rear sensor area 5 of the sensor body 2 can be deflected relative to the front contact area 3 without the sensor body 2 being damaged.

The rear sensor area 5 of the sensor body 2 essentially has an octagonal base area and corresponds in its material thickness to the front contact area 3. A top side 15 of the rear sensor area 5 has a central recess 16 with a circular base area, the depth of which is the depth of the weakening 14 of the central connection area 4 corresponds to what also consists of Figure 3c emerges.

In the radial center of the circular recess 16 an upright scanning member 17 is arranged, the radial is completely surrounded by a ferromagnetic core 18. When used, the sensing element 17 is in contact with the label tape or with the labels attached to the label tape.

The ferromagnetic core 18 is made of iron, for example. In this exemplary embodiment, it has an inner vertical annular projection 18.1 and an outer annular projection 18.2 interrupted on both sides by openings 21 in the longitudinal direction L of the label sensor 1, between which an annular groove 18.3 for receiving a coil 19 is formed. The coil 19 is formed here by a winding made of wound copper wire

The ring projections 18.1, 18.2 take up approximately half the height of the scanning member 17. The winding 19 consists essentially of (insulated) copper wire. The winding 19 surrounds the inner annular projection 18.1. In addition, the outer annular projection 18. 2 of the core 18 has two openings 21, which lie opposite one another and are formed in the longitudinal direction L of the label sensor 1. An electromagnet is formed by the core 18 and the coil 19 arranged around it.

The sensing element 17, the core 18 and the coil 19 protrude beyond the upper side 15 of the rear sensor area 5.

Figure 1b shows the label sensor 1 of Figure 1a under supervision. From the supervision of the Figure 1b it can be seen that the width of the front contact area 3 at the depths of the funnel-shaped recesses 6 corresponds to the width of the central connection area 4 and the maximum transverse extent of the sensor body 2 in the rear sensor area 5.

The diameter of the mounting hole 22 corresponds approximately to the diameter of the core 18 in the rear sensor area 5 and is larger than the respective diameter of the five contact holes 8 in the front contact area 3. The radial centers of the central contact hole 8, the mounting hole 22 and the circular recess 16 are located on a straight line which is aligned parallel to the longitudinal direction L of the label sensor 1 and which coincides with the section line AA shown in FIG.

Figure 1c shows the label sensor 1 of Figures 1a and 1b in a schematic section along the in Figure 1b drawn section line AA.

The upper sides of the contact pins 10 of the electrical contact part 9 are flush with the upper side 11 of the front contact area 3 of the sensor body 2. As already mentioned, the electrical contact part 9 is arranged on the underside 12 of the sensor body 2, so that the contact feet 13 of the contact device 9 extend away from the sensor body 2.

In the rear sensor area 5 of the sensor body 2, the structure already described with scanning element 17, core 18 and winding 19 can be seen. The underside 12 of the sensor body 2 in the rear sensor area 5 is provided with an opening 23 in which a socket-shaped end piece 24 of the sensing element 17 is arranged such that the end piece 24 is flush with the underside 12 of the sensor body 2. The sensing element 17 is connected to the sensor body 2 in a form-fitting, force-fitting and / or material fit via holding devices (not shown).

The Figures 2a to 2c show a further exemplary embodiment of the label sensor 2, in which the central connecting area 4 is provided with a centrally arranged and elongated opening 14a. The opening 14a extends in the longitudinal direction L over the entire length of the central connecting region 4. Due to the material weakening of the sensor body 2 caused by the opening 14a, the required flexibility of the sensor body 2 is achieved without the need for in the exemplary embodiment Figures 2a to 2c the strength of the central connection area 4 must be reduced.

The label sensor 1 can also be provided both with a recess 14 and with an opening 14a, which is an embodiment of the label sensor 2 according to FIGS Figures 3a to 3c shows.

Figure 4 shows - not true to scale - a schematic structure of an embodiment of the sensor body 2 with a multilayer printed circuit board. For the sake of clarity, only the sensor body 2 is shown, without the structural configurations of the areas 3, 5. In FIG Figure 4 the front contact area 3 is located on the left-hand side and the middle connection area 4 with the recess 14 on the right-hand side is the rear sensor area 5.

The structure of the in Figure 4 Sensor body 2 shown starting from bottom to top explained:
The in Figure 4 The structure shown can be roughly divided vertically into three panel layers. The first plate layer 25 consists of a central electrically insulating carrier layer 26, on the top and bottom of each of which a conductor plane 27 is provided with metallic conductor tracks. The carrier layer 26 of the first board layer 25 consists of a fiberglass-epoxy resin composite material such as the electrically insulating material FR4, which is known in the field of printed circuit boards. The two conductor planes 27 arranged on the carrier layer 26 have copper conductors and are formed from a plurality of conductor tracks in accordance with the desired electrical contacting, for example by an etching process. A possible configuration of the conductor tracks is further down in the Figures 9 to 11 shown.

Although both conductor levels 27 are arranged above and below the carrier layer 26 and are thus spatially separated and thus electrically isolated from one another by the carrier layer 26 arranged in between, both conductor levels 27 can be connected to one another by means of vertical electrically conductive connections (vertical interconnect access - VIA) (not shown) be electrically connected. VIAs have openings formed in the carrier layer 26 and possibly also in the conductor planes 27, which are provided with electrically conductive material and thus enable an electrical connection between the two conductor planes 27. In the exemplary embodiment shown, the thickness of the carrier layer 26 is Figure 4 approximately 510 μm, the thickness of each conductor plane 27 approximately 35 μm.

In the front contact area 3, a second plate layer 29 is arranged above the upper conductor plane 27 after a first intermediate layer 28.

The first intermediate layer 28 is designed as a “no-flow prepreg”. "Prepreg" usually denotes a semi-finished product made of resin and carrier material, and essentially corresponds to a not yet cured precursor of the base material for the carrier layer 26. The prepreg material is initially soft by supplying heat and then finally hardens to join the hard panel layers, whereby it is pressed with the surrounding layers. After curing and pressing, the prepreg layer connects the layers immediately surrounding it.

“No-flow prepregs” are prepregs that have a particularly high viscosity, particularly during the final pressing and curing process. As a result, the "no-flow prepreg" material hardens to a largely dimensionally stable condition. In the specific design of the Figure 4 The first intermediate layer 28, designed as a “no-flow prepreg”, serves to prevent the material from flowing into the region of the recess 14 of the central connecting region 4 during the pressing and curing process. The thickness of the first intermediate layer 28 is in the double-digit micrometer range.

The second panel layer 29 above the first intermediate layer 28 consists of a carrier layer 30, a "no-flow prepreg" layer 31 on the underside of the carrier layer 30 and a prepreg layer 32 arranged above the carrier layer 30. The one arranged below the carrier layer 30 "No-flow prepreg" layer 31 essentially corresponds in terms of material and thickness to the first intermediate layer 28 and, like all the other layers of the second and third panel layers 29, 34, extends only to the front contact area 3 and the rear contact area Sensor area 5 of sensor body 2.

The thickness and material of the carrier layer 30 of the second plate layer 29 corresponds to the carrier layer 26 of the first plate layer 25. Above the carrier layer 30 of the second plate layer 29, the prepreg layer 32 is arranged, the viscosity of which is higher than that in the pressing and curing process the "no-flow prepreg" layer 31 and whose thickness is in the double-digit micrometer range.

A second intermediate layer 33 is arranged above the prepreg layer 32 of the second panel layer 29, the thickness and material of which corresponds to the prepreg layer 32 arranged underneath. Above the second intermediate layer 33, a third plate layer 34 is arranged, which has a middle carrier layer 35, which above and below each carries a conductor level 36 with copper tracks. The materials and the arrangement of the layers of the third plate layer 34 correspond essentially to the first plate layer 25, it being possible for the detailed configuration of the conductor planes 27, 36, in particular with regard to the conductor tracks, to be configured differently. Individual or all conductor levels 27, 36 can be electrically connected to one another via VIAs (not shown).

The structure of the rear sensor area 5 according to Figure 4 corresponds to the structure of the front contact area 3 explained above, so that reference is made to it. In particular, the conductor planes 36 of the rear sensor area 5 can be electrically connected to one another via the conductor planes 27 of the first plate layer 25 with the conductor planes 36 of the third plate layer 24 in the front contact area 3 by means of VIAs (not shown).

The conductor tracks of the upper conductor level 36 of the third plate layer 34 of the front contact area 3, the upper conductor level 27 of the first plate layer 25 in the middle connection area 4 and the upper conductor level 36 of the third plate layer 34 of the rear sensor area 5 are provided with a coating 37 of nickel and gold , referred to as "NiAu" or also as "Electroless Nickel Gold". The coating has a thickness of 3 to 6 μm and serves on the one hand as a solder bridge (Ni) for additionally provided components that can be soldered onto the sensor body 2 and on the other hand as protection against oxidation (Au).

Figure 5 shows a schematic side view of a further embodiment of the sensor body 2 in a simplified representation similar to that in FIG Figure 4 illustration shown. The sensor body 2 has according to Figure 5 again three plate layers 25, 29, 34, the first plate layer 25 as a rectangle and the second plate layer 29 together with the third plate layer 34 in the front contact area 3 and in the rear sensor area 5 also as a rectangle. The carrier layer (not shown) of the first plate layer 25 is designed as a polyamide film and has a significantly reduced thickness compared to the second and third plate layers 29, 34, which is shown in FIG Figure 5 is not shown to scale. The carrier layer of the first plate layer 25 is provided on both sides with a conductor level made of copper, which is also not shown in FIG Figure 5 is drawn. The structure in detail is the same as in the design of the Figure 4 , to which reference is made.

On the underside 12 of the lower first plate layer 25 in Figure 5 is in addition to the subject of Figure 4 a Coating 37a made of polyamide, it being possible for other plastics to be provided for the coating 37a. The thickness of the coating 37a can be up to a multiple of the thickness of the first plate layer 25. Due to the coating 37a, the rigidity of the sensor body increases, so that its properties with regard to its elasticity can be adjusted by the design of the coating 37a.

In Figure 5 the first plate layer 25, the second and third plate layers 29, 34 and the coating 37a are shown as spaced apart from one another, which, however, is only for the sake of clarity, since the components mentioned are of course actually in contact with one another.

Figure 6 shows a sensor body 2 in a further embodiment in a perspective view obliquely from above. The front contact area 3 and the middle connection area 4 correspond to the previously shown embodiment of FIG Fig. 1 configured, so that the configuration of the rear sensor area 5 will be discussed below.

The rear sensor area 5 is provided with an essentially arched opening 38 with the exception of a connecting web 39 on which a cylindrical sensor socket 40 is molded. The connecting web 39 and the sensor socket 40 are designed in one piece with the rest of the sensor body 2 and as a multi-layer printed circuit board, the sensor socket 40 having a central recess 41. In Figure 7 is the electromagnet made of ferromagnetic core 18 and coil 19 to the sensor body 2 of the Figure 6 arranged such that the sensor socket 40 of the annular groove 18.3 of the Kerns 18 is added. The inner annular projection 18.1 extends through the central recess 41 and the outer annular projection 18.2 extends through the arcuate opening 38.

In the cylindrical sensor socket 40 of the Figures 6 and 7 the coil 19 is formed by conductor tracks of the conductor planes 27 of the first plate layer 25 (see the structure of the circuit board according to FIG Figure 4 ). The conductor tracks are drawn in on the sensor socket 40 by lines running in the circumferential direction, and they are actually designed in the sensor socket 40 as an integrated component in the printed circuit board.

In Figure 8 a further embodiment of the label sensor 1 is shown, the middle connecting area 4, or the area of the weakening 14 being marked with a thicker line thickness for the sake of clarity. In addition, the embodiment of the label sensor 1 according to FIG Figure 8 the five already mentioned contact bores 8 transversely to the longitudinal direction L of the label sensor 1 and the also already mentioned fastening bore 22. In addition, two VIAs 44 for the winding 19 and two VIAs 47 for a discharge protection 45 are formed in the rear sensor area 5, which is described further below is.

The label sensor 1 according to Figure 8 has a sensor body 2, which is designed as a three-layer printed circuit board, and for example in the in Figure 4 shown embodiment is present, so that three levels of conductor tracks are formed in the depth direction, which are explained below. Figure 9 shows an upper conductor level, for example one of the two in Figure 4 The conductor planes 36 shown correspond to the third plate layer 34. In the area of this conductor level, the components of the front contact area 3 and the rear sensor area 5 are spatially separated from one another, since there is no continuous conductor level due to the weakening 14 in the central connection area 4.

The front contact area 3 has in Figure 9 an essentially circumferential front protective line 46, which serves as an ESD protective structure 45. The ESD protective structure 45 protects the conductor tracks and the electronic components of the sensor body 2, similar to a lightning conductor, from locally limited voltage peaks due to electrostatic discharges (ESD: electro static discharge). This prevents damage as a result of electrical charges.

The contact bores 8 are subsequently perpendicular to the longitudinal direction L of the sensor body according to FIG Figure 9 counted from top to bottom, so that the fifth contact hole is the one that is furthest down.

The front protective line 46 is connected to the third contact hole 8, which is designed as a ground connection. For example, if an - electrostatically charged - user touches the in Figure 9 The upper conductor level shown, the electrostatic potential of the user is diverted via the - earthed - front protective line before electronic components of the sensor body are damaged.

The second and fourth contact bores 5 are electrically connected to temperature-dependent resistors, the temperature-dependent resistors on solder points in Figure 9 shown as black rectangles) can be soldered on. The temperature-dependent resistors are assigned capacitors 50 connected in parallel in order to stabilize the voltages at the said resistors, which can also be applied by soldering points drawn as black rectangles. In the rear sensor area 5 of the sensor body 2, two connections 43 for the coil 19 are shown as black circles, each of which is electrically connected to a VIA 44. The VIA 47 is formed adjacent to the two VIAs 44 for the coil 19 and is electrically connected to a rear protective line 48 in each case.

Figure 10 shows a middle conductor level according to Figure 4 the upper conductor level 27 of the first plate layer 25 corresponds. The front contact area 3 is electrically connected to the rear sensor area 5 by means of this conductor plane 27. The first of the five contact bores 8 of the front contact area 3 is connected via a conductor track to the upper VIA 44 for the coil 19 at approximately the same height. In the same way, the fifth contact hole 8 is connected to the VIA 44 for the contacting 43 of the coil 19 at the same height.

Figure 11 shows a lower conductor level, which in Figure 4 corresponds to the lower conductor plane 27 of the first plate layer 25 and, in particular, like the middle conductor plane according to FIG Figure 10 , electrically connects the front contact area 3 to the rear sensor area 5 via conductor tracks. The lower conductor level according to Figure 11 has a lower Protective line 49, which connects the fastening bore 22 and the third contact bore 8 in the front contact area 3 with the two VIAs 47 of the rear sensor area 5 for connection to the rear protective line 48 of FIG Figure 9 connects the upper conductor level shown.

In Figure 12 is a possible electrical circuit diagram for the sensor head of the Figures 8 to 11 shown. The contact holes 8 are shown on the left-hand side. The first and fifth contact bores 8 are connected to the connections 43 for the coil 19. The second and fourth contact bores 8 are both connected to the temperature-dependent resistor 42 and a capacitor 50 connected in parallel therewith. The third contact hole 8 is connected to the protective lines 46, 48, 49 of the ESD protective structure 45.

In the application, the label sensor 1 is in direct contact with a label tape provided with labels, the sensing element 17 touching the label tape on the side facing the labels. A ferromagnetic part is arranged on the side of the label tape opposite the labels, so that both the label tape and the label sensor are in the magnetic field of the permanent magnet.

If the label strip is driven, a label passes between the label strip and the scanning element 17, so that the rear sensor area is deflected. As a result of this movement, due to the inductance of the core 18 and the coil 19, a changed electrical signal can be measured by changing the distance to the rear ferromagnetic part, which is used for detection and switching processes becomes. In this way, the label strip can be stopped - possibly with a predetermined lead time - for removing the label and driven again after the removal has taken place, so that the process can be repeated with the next label.

Claims (13)

1. Label sensor (1) for scanning labels on the carrier strip, comprising a sensor body (2) carrying a ferromagnetic core (18), a coil (19) and a scanning element (17), characterized in that the sensor body (2) is embodied in the form of a printed circuit board with at least one electrically insulating carrier layer (26, 30, 35) and at least one conductor plane (27, 36) having electric conductors, which is arranged on the carrier layer (26, 30, 35), and in that a central connection region (4) of the sensor body (2) has a lower thickness or weakening (14) compared to the contact and sensor regions (3, 5), which adjoin it on both sides.
2. Label sensor according to Claim 1, characterized in that the weakening (14) of the sensor body (2) is milled.
3. Label sensor according to Claim 1 or 2, characterized in that the sensor body (2) is embodied in the form of a multilayer printed circuit board with at least one pre-preg layer (31, 32).
4. Label sensor according to Claim 3, characterized in that the pre-preg layer (31, 32) is embodied in the form of a no-flow pre-preg layer (31), in which the region of lower thickness (14) is exposed.
5. Label sensor according to Claim 3 or 4, characterized in that upper plate layers (29, 34) arranged above the pre-preg layer are removed by chiseling in the region of low thickness (14).
6. Label sensor according to one of the preceding claims, characterized in that a lower side (12) of the sensor body (2) that is remote from the scanning element (17) is provided at least partially with a coating (37a).
7. Label sensor according to one of the preceding claims, characterized in that the central connection region (4) of the sensor body (2) is provided with an opening (14a).
8. Label sensor according to one of the preceding claims, characterized in that the coil (19) is embodied in the form of a conductor track (27, 36) of the sensor body (2) or of a wire-wound winding.
9. Label sensor according to one of the preceding claims, characterized in that the ferromagnetic core (18) has concentric inner and outer ring projections (18.1, 18.2), between which an annular groove (18.3) for receiving the coil (19) is formed.
10. Label sensor according to Claim 9, characterized in that the outer ring projection (18.2) has openings (21) in the longitudinal direction (L) of the label sensor (1).
11. Label sensor according to one of the preceding claims, characterized in that the sensor body (2) has an ESD protection structure (45) for protecting against in particular electrostatic discharges.
12. Label sensor according to Claim 11, characterized in that the ESD protection structure (12) is embodied in the form of at least one protective earth line (46, 48, 49) .
13. Label sensor according to one of the preceding claims, characterized in that the sensor body (2) has at least one temperature-dependent resistor (42).

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