EP2102828B1 - Sensor and device for examining sheet material, and sensor maintenance method - Google Patents

Abstract

In banknote processing machines, banknotes are conveyed by a conveying system and pass through a sensor section. In some sensors, the passing banknotes touch the front side of the sensor housing, resulting in wear of the front sides, which can affect the conveying process of the banknotes. When the sensor fronts are worn, only individual front elements of the sensor component are replaced rather than entire sensor components, as used to be the case. One or more front elements which are removable and can thus be replaced with little effort are fastened to the sensor housing side facing the banknotes. Said front elements have no contact with the interior of the housing and the sensitive measuring elements located therein. The measuring elements remain encapsulated in a dust-tight manner in the housing of the sensor component when the front elements are removed from the housing for maintenance. Preferably, the front elements have a comb structure which makes it easier to convey the banknotes at the transition between the sensor components.

Description

The invention relates to a sensor for checking sheet material, such as banknotes, and to a device in which this sensor is incorporated, such as a bank-note processing machine. Furthermore, the invention relates to a method for the maintenance of the sensors.

In banknote processing machines, banknotes are checked by means of sensors, for example in their own way with respect to currency or denomination, their authenticity or their condition. For this purpose, the banknotes are transported by a transport system and thereby pass through a sensor path with one or more sensors. From the prior art (eg DE 32 42 789 C1 Banknote processing machines are known whose sensors each have two sensor components which are arranged on opposite sides of the sensor section. In the sensor components sensitive measuring elements are arranged, which must be protected from environmental influences - for example, dust and dirt particles that are introduced by the banknotes into the machine.

In addition, from the US 5013911 A an optical sensor for testing sheet material is known, on whose front side a guide element is arranged, along which the sheet material is transported past. On the guide element, a mounting bracket is fixed, which serves to receive an optical sensor unit.

Furthermore, from the US 5172000 A an optical sensor for detecting the end of a transported sheet in a printer. In front of the optical sensor, a transparent plate is arranged, through which the light of the optical sensor is transmitted and which is intended to protect the optical sensor from dust.

In some sensors, the banknotes guided past the sensor components contact the front side of the housing of the sensor component facing the banknotes. In the course of time, the front surface becomes worn, which can impair the transport of banknotes. In order to maintain the banknote processing machines installed at the customer, in the event of wear, complete sensor components must be replaced and replaced with new ones. After replacement, readjustment of the replaced sensor components may also be required. Overall, this means a lot of effort and costs for the maintenance of the sensors of banknote processing machines.
When advancing banknotes to sensors according to the prior art, banknote jamming can occur at high transport speeds. In particular, bottlenecks and transitions between different components which laterally limit the transport path of the bank notes are critical.

The object of the invention is therefore to reduce the effort for the maintenance of the sensors and to achieve a trouble-free transport of the sheet material along the sensors even at high transport speeds.

This object is achieved by the sensor having the features mentioned in claim 1.

The invention is based on the idea of equipping the sides of the sensor components facing the sheet material with front elements. If the sensor fronts wear or become soiled, it is no longer necessary to replace the complete sensor components, but only the front elements of the sensor components. On the side facing the sheet material of the housing of the respective sensor component are one or more front elements attached, which can be removed from the housing and thereby replaced with little effort. The at least one front element is advantageously arranged outside the housing and has no contact with the inner region of the housing and the sensitive, for example optical measuring elements arranged therein for detecting or generating the measuring signal of the sensor. If the at least one front element is removed from the housing for maintenance, the measuring elements therefore remain dust-tightly encapsulated in the housing of the sensor component. The replacement of the at least one front element can thus be carried out without negative influence on the measuring technology and the function of the sensor. Advantageously, even those measuring elements, which are directly enclosed by the housing of the sensor component and therefore would be insufficiently protected when the housing is opened, remain encapsulated by the housing and thus protected from dust and dirt particles.

The removable front panels also simplify the cleaning of soiled sensor fronts. Instead of a less practicable cleaning within the device contaminated front elements can be removed in a short stop of the operation of the device and replaced by new or cleaned front elements. Thus, the operation of the device must be interrupted only briefly. In this case, either individual front elements can be removed and replaced or even the complete front of the sensor front elements and arranged on the sensor front window. In the event that the window is to be removed for cleaning, the sensor components - for example, by an additional window - designed so that their housing are dust-tight encapsulated despite the window removed.

For servicing a sensor, the front element (s) and / or the window are removed from the sensor component, and subsequently a new or cleaned front element and / or a new or cleaned window is instead arranged on the sensor component. The measuring elements remain encapsulated by the housing of the sensor component. As a new or cleaned front element and / or window can be used, for example, a previously removed front element or window.

During operation of the device, the front elements can at least temporarily contact the transported sheet material, which enters and leaves the detection range of the sensor. Due to the mechanical contact of the sheet material guided past the front elements are subject to wear, which is taken into account by the replacement of the front elements. To limit the wear as possible on the front elements and / or to avoid direct contact between the window and sheet material, the sheet material facing the window of the sensor components - from the perspective of the transported sheet - against the at least one front element of the sensor component can be arranged offset back.

The transport direction of the sheet material defines on the sensor components, which are arranged along the transport path of the sheet, each having an input side, on which the sheet material is guided into the detection range of the sensor component, and an output side, on which the sheet material is led out of the detection area. The at least one front element is preferably designed and attached to the housing of the sensor component in such a way that, on its surface facing the transport path, it is bevelled on its side facing the input side. In addition, it may also be bevelled on its side facing the output side. By these bevels, the at least one front element in the immediate Close to the transported sheet material obtuse and no transport affecting edges, so that the sheet material is guided in the front region of the sensor component. For a smooth sheet transport with low congestion is achieved.

The individual sensor components preferably consist of at least one front element and the housing, on the front side of which the at least one front element is arranged. In one embodiment, a plurality, for example two front elements are fastened to the front side of the sensor component, one of which is arranged on the input side and the other on the output side. The two front elements are preferably designed so that they can be mounted either on the input side or on the output side. In another embodiment, a front element that extends from the input side to the output side of the sensor component and forms a frame around the window of the sensor component is fastened to the front side of the sensor components.

The front elements are, for example, designed such that they can be fastened optionally in two different orientations to the housing of the sensor component, wherein the two orientations can be converted into one another by a 180 ° rotation of the respective front element about an axis perpendicular to a front plane of the sensor component.

In a preferred embodiment, the front elements each have one or more comb structures, which are arranged on the input side and / or on the output side of the sensor component. The comb structures have a plurality of gaps and a plurality of teeth, which are chamfered, for example, on their surface, and can also protrude on the input and / or on the output side of the sensor component on the housing of the sensor component. To a fast and trouble-free Transporting the sheet material of a sensor component to allow a neighboring sensor component, the comb structures of adjacent front elements are preferably formed so that they fit together and / or mutually interlock, ie that teeth of a front element can be at least partially disposed in gaps of the adjacent front element and vice versa. This facilitates the sheet transport in and out of the detection range of the sensor, especially in the transition region of a plurality of adjacently arranged sensor components.

In order to be able to use the same front elements on various adjacent sensor components, the comb structures of the front elements are preferably designed such that they not only line up in a certain order but can also fit together in reverse order and / or mutually interlocking. Particularly advantageously, each individual front element, regardless of the order of the sensor components along the transport path of the sheet material, be used as a front element of each of the sensor components. For this purpose, the front element on the input side of the sensor component has at least one first comb structure, which mates with at least one second comb structure on the output side of the sensor component, wherein the second comb structure is formed as a counterpart of the first.

Particularly preferably, at least some of the gaps of the comb structures are positioned such that a plurality of transport rollers arranged adjacent to the sensor component can be arranged at least partially in the gaps. The transport rollers protrude or are at least partially beyond the front plane of the sensor component or protrude beyond the front elements in the direction perpendicular to the plane of the front elements, in Direction of the transport route of the sheet material. The transport rollers are preferably arranged along dividing lines, which respectively define the transition between the adjacently arranged sensor components or between their front elements. In particular, the vertices of the transport rollers are arranged along the dividing lines between the adjacent sensor components or between the adjacent front elements. At the transition region between adjacent sensor components which is critical for sheet transport, the sheet material is at least partially raised by the projecting or protruding transport rollers. The sheet material is thereby advantageously passed from one sensor component over the parting line to the adjacent sensor component. This prevents that the sheet material threads in the transition area or gets stuck and causes a traffic jam.

Particularly preferably, the at least one front element at least partially made of a non-transparent material, so that, for example, in the case of an optical sensor, the leakage of stray light through the front element is avoided. In addition, the surface of the at least one front element preferably has favorable sliding properties relative to the transported sheet material. For this purpose, for example, a material with a low coefficient of sliding friction can be attached to the sheet material on the surface of the at least one front element or the surface can be specially smoothed. Also, the entire front element can be constructed of the material with low sliding friction coefficient. As a material for the surface of the at least one front element is preferably used hardened or hard-coated aluminum or plastics with low coefficient of sliding friction to sheet material containing, for example, nylon, polyamide or ABS (acrylonitrile-butadiene-styrene).

To attach the front elements to the housing of the respective sensor component, this can be glued, for example with a double-sided coated with adhesive tape. However, the front elements may also be mechanically clamped or screwed to the housing or attached by a snap connection to the housing.

In a device for testing sheet material, a plurality of sensor components can be arranged on one side or on both sides of the transport path of the sheet material. A sensor may for example consist of two sensor components which are arranged on both sides of the transport path and facing each other.

The inventively constructed sensor components with removable front elements can also achieve that the housing of the sensor components can be used with the measuring elements disposed therein either on one or the other of the two opposite sides of the transport path. In the case of one or more front side of a sensor component bevelled on one side on the input side, only the front element (s) corresponding to the transport direction of the sheet material are to be mounted so that their bevel lies on the input side of the sensor component. The customer service must therefore advantageously hold only one type of sensor components whose front elements can be attached to the housing in one of the two required orientations as required.

The sensor components of the sensors according to the invention can be parts of various sensors, such as mechanical sensors, magnetic sensors, capacitive sensors, photosensors in UV, VIS or IR or ultrasonic sensors.

The sheet material, for the examination of which the sensor according to the invention can be used, are, for example, bank notes, value documents, tickets or the like. The device for checking sheet material is, for example, a banknote processing machine.

The invention will be described by way of example with reference to the accompanying drawings.

Fig. 1

eine Schnittansicht eines Sensors mit zwei einander gegenüber liegend angeordneten Sensorkomponenten, zwischen denen die Banknoten hindurch geführt werden, und

Fig. 2a-e

fünf verschiedene Ausgestaltungsvarianten der Frontseiten der Sensorkomponenten mit den abnehmbaren Frontelementen, und

Fig. 3a-d

perspektivische Ansichten mehrerer benachbarter (Fig. 3a) bzw. gegenüberliegender (Fig. 3c, 3d) Sensorkomponenten mit Frontelementen, die auf der Eingangs- und Ausgangsseite Kammstrukturen besitzen, sowie eine Detailansicht zum Ineinandergreifen der Kammstrukturen (Fig. 3b), und

Fig. 4

eine Seitenansicht zweier gegenüberliegender Sensorkomponenten jeweils mit dem Übergang zu einer benachbarten Sensorkomponente, an dem die Frontelemente kammartig ineinander greifen und an dem Transportrollen für das Blattgut angeordnet sind.

Show it:

Fig. 1

a sectional view of a sensor with two oppositely arranged sensor components, between which the banknotes are passed through, and

Fig. 2a-e

five different design variants of the front sides of the sensor components with the removable front elements, and

Fig. 3a-d

perspective views of several neighboring ( Fig. 3a ) or opposite ( Fig. 3c, 3d ) Sensor components with front elements, which have comb structures on the input and output sides, as well as a detailed view of the meshing of the comb structures ( Fig. 3b ), and

Fig. 4

a side view of two opposing sensor components each with the transition to an adjacent sensor component, on which the front elements mesh with each other and are arranged on the transport rollers for the sheet material.

In FIG. 1 For example, an optical sensor of a bank-note processing machine with two sensor components A and B is shown. Between two sensor components A, B is a gap for the transport of banknotes 5 along its transport path provided in the transport direction, which is indicated with the direction away from the banknote 5 arrow. At the respective front sides of the two sensor components A, B, the two housings 1a, 1b are closed dust-tight by two windows 2a, 2b. Two front elements 3a, 4a and 3b, 4b are respectively arranged on the two housings 1a, 1b. The windows 2a, 2b can, as in FIG. 1 shown to be set back in comparison to the front elements 3a, 4a and 3b, 4b. In this case, it is necessary for a proper banknote transport, the front elements 4a, 4b, which are mounted on the output side of the sensor components A, B, taper on the side facing the input side of the sensor components A, B side. In order to facilitate the insertion of the banknote 5 into the detection range of the sensor, the front elements 3a, 3b, which are arranged on the input side of the sensor components A, B, are chamfered on their side facing the input side, cf. FIG. 1 , The front elements 3a, 4a and 3b, 4b can be removed from their respective housing 1a or 1b while the respective housing 1a, 1b remains closed, so that the measuring elements 6a, 6b arranged in the housings 1a, 1b (shown only schematically) remain encapsulated and so protected from dust and dirt particles. The front elements 3a, 4a and 3b, 4b are for this purpose detachably connected to the respective housing 1a or 1b, for example by a double-sided coated adhesive tape. The banknote transport can either take place in such a way that the banknotes 5 touch the front sides of the sensor components A, B, ie the elements 2a, 3a, 4a or 2b, 3b, 4b. Due to the contact between banknotes 5 and front elements, it is advantageous in this case to equip the front elements 3a, 3b, 4a, 4b on their surface with a special material which has favorable sliding properties to the banknotes, for example with one or more of the plastics Nylon, polyamide or ABS-containing plastic mixtures such. B. ABS polycarbonate. alternative However, a non-contact transport of the banknotes 5 through the gap between the sensor components A, B done.

In the in FIG. 1 In the example shown, the sensor components A and B can be mounted either on one side of the transport path (in FIG FIG. 1 above) or - after a 180 ° rotation about an axis perpendicular to the plane of the drawing - on the opposite side of the transport path (in FIG. 1 below). The housings 1a, 1b with the measuring elements 6a, 6b arranged therein can therefore be used on each of the two opposite sides of the transport path. The sensor components A and B can therefore be identical except for the arrangement of the front elements. The front elements 3a, 4a and 3b, 4b attached to the housings 1a and 1b are to be attached to the two opposite sensor components A, B in different orientations relative to the respective sensor component because of their one-sided bevel. These orientations are respectively defined by the transport direction of the banknotes 5 relative to the respective sensor component A, B. In order to be able to attach them oriented in both directions, the front elements 3a, 3b, 4a, 4b are constructed and fastened so that they can be mounted either with the chamfer on the input or the output side to the respective housing 1a, 1b.

In the case of front elements 3, 4 which are chamfered on one side on the side facing the input side of the sensor component, the transport direction of the bank notes relative to the sensor component is predetermined, as indicated by the arrows in FIG FIG. 2a shown. The correct orientation of the front elements must be taken into account in particular when the measuring technology of the respective sensor requires that the banknotes pass very close to the sensor front. In addition to the one-sided bevelled front elements 3, 4, the front elements 30, 30 ', 40, 40' of an alternative embodiment can also be used on both sides, bevelled both on the input and on the output side, cf. FIGS. 2b, 2c , Due to the symmetrical design of the front elements 30, 30 ', 40, 40', the sensor components can also be used without specially adapted orientation of their front elements on each of the two sides of the transport path. In this way, the banknotes can be transported in both directions relative to the sensor component, cf. the arrows in the FIGS. 2b, 2c , The windows 20, 20 'may, for example, be straight at their surface (compare window 20 in FIG FIG. 2b ) or on one (not shown) or on both sides (see window 20 'in Figure 2c ) beveled.

In a further alternative embodiment, the windows 200 and 2000 and the front elements 300, 400 and 3000, 4000 can also be arranged flush so that there are no steps in the immediate vicinity of the transported bank notes between these elements, cf. FIGS. 2d and 2e , By additional beveling of the front elements 300, 400 on the outer sides of the sensor component, the banknotes can then also be transported in both directions relative to the sensor component, cf. the arrows in Figure 2d , For sensor components that are mounted so that their front sufficiently maintain a distance to the transported banknotes, or their measurement allows a sufficient distance to the transported banknotes, the simple geometry of the front elements 3000, 4000 can satisfy without bevels, see. the more spaced arrows in FIG. 2e , In this case, it is also possible to transport the banknotes in both directions relative to the sensor component.

The illustrations FIG. 2 show only a few possibilities for the arrangement of front elements and windows. However, as long as the transport of banknotes is not affected, details of these arrangements can also be combined. For example, one or both sides could be used Beveled front elements 4 or 40 instead of the front elements 400 or 4000 or the window 20 'instead of the window 2 are used. In the FIG. 2 illustrated embodiments of the sensor front concern not only the case of two front elements, but also the embodiments described below with a single front element per sensor component.

In FIG. 3a is a perspective view of three adjacent sensor components A, C, E, which are arranged on one side of the transport path of the sheet material 5. This arrangement may for example be part of a sensor path in a banknote processing machine. Opposite to the sensor components A, C, E in each case further sensor components B, D, F can be arranged, cf. Figure 3c , The sensor components with the housings 1a, 1c, 1e are each equipped with a front element 7a, 7c, 7e, on which the banknotes 5 are guided past in the direction of the arrow. The front elements 7a, 7c, 7e each have a comb structure 8, 8 'on their input and output sides.

FIG. 3b shows in detail the comb structures 8, 8 'of the front element 7a, which have a plurality of teeth Z and a plurality of gaps L. In some of the gaps L, the teeth Z of the adjacent front element 7c engage, which is structurally identical to the front element 7a. In some other, each directly positioned opposite to each other gaps L of the comb structures 8, 8 'of both adjacent front elements 7a, 7c transport rollers 9 are arranged, with which the sheet material 5 is guided past the sensor components A, C, E. The comb structures 8, 8 'of the adjacent front elements 7a, 7c fit together like counterparts. The front elements 7a-7f are transferable from one sensor component to the next and can be arranged in any order.

Figure 3c shows analogously to FIG. 3a the arrangement of several sensor components along a sensor path for banknotes. Of the sensor components A, B, C, D, E, F, which are fastened for example on a receiving plate 20, only the front elements 7a-7f are shown, as well as by way of example the housings 1a, 1b of two opposing sensor components A and B. The housings 1c-1f are in the for clarity Figure 3c not drawn. There is a narrow gap between the front elements 7a-7f, in which bank notes are guided past the sensor components AF along their transport path, for example with the aid of the transport rollers 9.

The front parts of the opposing sensor components A and B are shown in detail in FIG 3d figure shown. In order to fasten the front elements 7a-7f to their respective housings 1a-1f, the sensor components have a plurality of springs 10. For example, four springs are used per front element, each on the input and output side of the sensor component and on the right and left of the transport path of the banknotes (top and bottom in Figure 3c ) are arranged. The springs 10 are screwed to the front element and are each clamped against a provided for each spring 10 mounting pin 11 which is attached to the respective housing 1a, 1b of the sensor components A, B at the appropriate location. The springs 10 clamped to the fastening pins 11 form a snap connection between the housing 1a, 1b and the front element 7a, 7b of the respective sensor component A, B.

In FIG. 4 is a section of the front parts of the sensor components AF shown in side view. The transport rollers 9 pass through the front elements 7a-7f in the gaps L provided therefor (cf. FIG. 3b ) and protrude beyond the banknotes 5 facing surfaces of the front elements 7a-7f. The comb-toothed front elements 7a, 7c and 7e and 7b, 7d and 7f are each separated by a dividing line T, which intersects the teeth of the adjacent front elements symmetrically, for example. In order to ensure a trouble-free banknote transport between the adjacent sensor components A, C and E or B, D and F, the transport rollers 9 are arranged so that their vertex lies approximately on the dividing line T. In addition, since the transport rollers 9 survive beyond the surfaces of the front elements 7a-7f, the banknotes 5 guided along the sensor path are slightly raised by the transport rollers 9 and safely conveyed over the transitions between the front elements 7a-7f.

Claims (15)

1. A sensor for checking sheet material (5), in particular bank notes, having at least one sensor component (A, B, C, D, E, F) which has a housing (1a-1f) in which measuring elements (6a-6f) of the sensor component (A-F) are arranged, and which has at least one front element (3, 4, 3a, 4a, 3b, 4b, 30, 40, 30', 40', 300, 400, 3000, 4000, 7a-7f) which is arranged at the side of the sensor component which is provided to face the transported sheet material (5) and which can be detached from the housing (1a-1f), whereby the measuring elements (6a-6f) remain encapsulated by the housing (1a-1f), characterized in that the sensor component (A-F) has an entry side at which the transported sheet material (5) is guided into a detection area of the sensor component (A-F) and an exit side at which the transported sheet material (5) is guided out of the detection area of the sensor component (A-F), wherein the front element (3, 4, 3a, 4a, 3b, 4b, 30, 40, 30', 40', 300, 400, 3000, 4000, 7a-7f) is chamfered at its side facing the entry side and/ or at its side facing the exit side.
2. The sensor according to claim 1, characterized in that the front element (3, 4, 3a, 4a, 3b, 4b, 30, 40, 30', 40', 300, 400, 3000, 4000, 7a-7f) can be detached from the housing (1a-1f), whereby the measuring elements (6a-6f) remain encapsulated in a dustproof enclosed inner area of the housing (1a-1f).
3. The sensor according to one or several of the preceding claims, characterized in that the sensor component (A-F) has a window (2, 2a-2f, 20, 20') which preferably is offset back in relation to the front element (3, 4, 3a, 4a, 3b, 4b, 30, 40, 30', 40', 7a-7f) of the sensor component (A-F).
4. The sensor according to claim 3, characterized in that the sensor component (A-F) has a front element (7a-7f) which forms a frame around the window (2a-2f) of the sensor component (A-F).
5. The sensor according to one or several of the preceding claims, characterized in that the front element (3, 4, 3a, 4a, 3b, 4b, 30, 40, 30', 40', 300, 400, 3000, 4000, 7a-7f) can be selectively fixed to the housing (1a-1f) of the sensor component (A-F) in two different orientations, whereby the two orientations can be converted into each other by a 180°-rotation of the front element (3, 4, 3a, 4a, 3b, 4b, 30, 40, 30', 40', 300, 400, 3000, 4000, 7a-7f) around an axis perpendicular to the plane of the front element (3, 4, 3a, 4a, 3b, 4b, 30, 40, 30', 40', 300, 400, 3000, 4000, 7a-7f).
6. The sensor according to one or several of the preceding claims, characterized in that the sensor component (A-F) has at least two front elements (3, 4, 3a, 4a, 3b, 4b, 30, 40, 30', 40', 300, 400, 3000, 4000) which are formed such that they can be selectively arranged at the entry side or at the exit side of the sensor component (A-F).
7. The sensor according to one or several of the preceding claims, characterized in that the front element (3, 4, 3a, 4a, 3b, 4b, 30, 40, 30', 40', 300, 400, 3000, 4000, 7a-7f) has at least one comb structure (8, 8') which is arranged at the entry side and/or at the exit side of the sensor component (A-F).
8. The sensor according to claim 7, characterized in that the front element (7a-7f) has at least one first comb structure (8) at the entry side and at least one second comb structure (8') at the exit side of the sensor component (A-F), whereby the second comb structure (8') is formed as a counterpart to the first comb structure (8).
9. The sensor according to one or several of claims 7 to 8, characterized in that the comb structure (8, 8') has several gaps (L) and several teeth (Z), whereby at least some of the gaps (L) of the comb structure (8, 8') are positioned such that several transport rollers (9) arranged adjacent to the sensor component (A-F) can be arranged at least partly in the gaps (L).
10. An apparatus for checking sheet material (5), in particular bank notes, with at least one sensor according to one or several of the preceding claims.
11. The apparatus for checking sheet material (5) according to claim 10, wherein the sensor component (A, C, E) is a first sensor component which is arranged at a first side of a transport path of the sheet material (5), characterized in that at least one second sensor component (B, D, F) of the sensor and/or at least one second sensor component (B, D, F) of at least one other sensor is arranged at a second side of the transport path of the sheet material (5) which is located opposite the first side of the transport path, whereby the first sensor component (A, C, E) can also be used at the second side of the transport path and/or the second sensor component (B, D, F) can also be used at the first side of the transport path.
12. The apparatus according to one or several of claims 10 to 11 with at least two sensor components (A-F) which are arranged adjacent to each other along the transport path of the sheet material (5), characterized in that the sensor components (A-F) respectively have at least one front element (3, 4, 3a, 4a, 3b, 4b, 30, 40, 30', 40', 300, 400, 3000, 4000, 7a-7f) with respectively at least one comb structure (8, 8'), whereby at least two of the comb structures (8, 8') of the front elements (3, 4, 3a, 4a, 3b, 4b, 30, 40, 30', 40', 300, 400, 3000, 4000, 7a-7f) of the sensor components arranged adjacent (A-F) mutually engage.
13. The apparatus according to one or several of claims 10 to 12 with at least one transport roller (9) and with at least two sensor components (A-F) which are arranged adjacent to each other along the transport path of the sheet material (5), characterized in that the sensor components arranged adjacent (A-F) have at least two mutually engaging front elements (3, 4, 3a, 4a, 3b, 4b, 30, 40, 30', 40', 300, 400, 3000, 4000, 7a-7f), the transition of which is defined by a dividing line (T) at which the transport roller (9) is arranged, whereby preferably a vertex of the transport roller (9) is located approximately on the dividing line (T).
14. A method for maintaining a sensor according to one or several of claims 1 to 9 with the following steps:

    - the front element (3, 4, 3a, 4a, 3b, 4b, 30, 40, 30', 40', 300, 400, 3000, 4000, 7a-7f) is detached from the sensor component (A-F),

    - a new or cleaned front element (3, 4, 3a, 4a, 3b, 4b, 30, 40, 30', 40', 300, 400, 3000, 4000, 7a-7f) is arranged at the sensor component (A-F), characterized in that during the maintenance the measuring elements (6a-6f) remain encapsulated by the housing (1a-1f) of the sensor component (A-F).
15. The method according to claim 14, characterized in that with the front element (3, 4, 3a, 4a, 3b, 4b, 30, 40, 30', 40', 300, 400, 3000, 4000, 7a-7f) a window (2, 2a-2f, 20, 20') of the sensor component (A-F) is also detached and that with the new or cleaned front element (3, 4, 3a, 4a, 3b, 4b, 30, 40, 30', 40', 300, 400, 3000, 4000, 7a-7f) a new or cleaned window (2, 2a-2f, 20, 20') is also arranged at the sensor component (A-F).

Images