Photoelectric sensor with weld connection between housing and optical module

Abstract

The invention relates to a photoelectric sensor, in particular a light curtain, comprising an elongate housing and an optical module that is arranged in the housing. Transmitting and / or receiving elements are arranged, spaced apart from one another, on the optical module, and the optical module is in contact with the housing via contact points, the contact points being flat. The optical module and the housing comprise plastics materials. According to the invention, at least one part of the contact points is formed as weld connections, wherein the housing forms a welded connection with the optical module.

Description

[0001] Photoelectric sensor with welded connection between housing and optics module

[0002] TECHNICAL FIELD OF THE INVENTION

[0003] The invention relates to a photoelectric sensor according to the preamble of claim 1 and a method for producing a photoelectric sensor according to claim 28.

[0004] BACKGROUND OF THE INVENTION

[0005] State-of-the-art photoelectric sensors typically comprise an aluminum profile in which at least one optical module is arranged. The optical module comprises the components that ensure the function of a photoelectric sensor. In addition to the transmitting and / or receiving elements on a circuit board, the support body for the circuit board, also called a tube, is generally part of the optical module. Depending on the design, the optical module may additionally comprise aperture and lens devices, with these devices preferably being attached to the support body. The aluminum profile has one or more openings along one long side. The optical modules are arranged in the aluminum profile such that the transmitting or receiving elements of the optical modules are directed towards the long side with the openings.A plastic strip is provided to be attached to the aluminum profile as a protective screen, which is transparent to the wavelength emitted by the optical modules. The protective screen can be attached to the aluminum profile either permanently or detachably. However, the resulting connection of two different materials creates a mechanical weak point and requires an additional manufacturing step in the photoelectric sensor. At the same time, the connection must be sufficiently tight to ensure that the optical module is splash-proof.

[0006] To position the optics module in the aluminum profile, guides are provided on the inside of the profile, running longitudinally along the aluminum profile. Opposing elements of the optics modules can be inserted into these guides, creating a positive and / or non-positive connection between the optics module and the aluminum profile. With this type of connection, a decision must be made between good assembly and high vibration and shock resistance. However, these two requirements are contradictory.

[0007] Instead of an aluminum profile, the profile can also be made of another material, such as plastic. Even with plastic profiles, the connection to the optics module is the same as with aluminum profiles, and therefore, with regard to the stability of this connection against vibration and shock movements, the same problems arise as with aluminum profiles.

[0008] US 2013 / 292554 A1 shows a light grid with an optical module, which is intended to be cost-effective to manufacture and easy to install. The optical module is arranged in a U-shaped profile. It has protruding elements that serve to precisely position the optical module within the housing. Furthermore, the optical module can have fastening means that serve to secure the optical module within the housing. The fastening means are preferably designed as locking elements. The fastening means can be firmly connected to the housing. Adhesive techniques, ultrasonic welding, or screw connections are provided for this purpose.

[0009] EP 1 770 414 A1 shows an optoelectronic arrangement with a plurality of light transmitter or light receiver modules that are electrically connected to one another by means of a flexible printed circuit board and assigned to a tube or lens body. The light transmitter or light receiver modules are attached directly to the respectively assigned tubes or lens bodies, and the flexible conductor edge is attached directly to the light transmitter or light receiver modules. A plastic housing is provided to accommodate the light transmitter or light receiver modules and is arranged on the tube by means of locking elements. Furthermore, the light transmitter or light receiver modules can be connected to the respectively assigned tubes or lens bodies via a welded joint. The tube can be mounted in a housing, wherein the housing has grooves for this purpose, via which the tube can be fixed.Patent EP2730952A1 discloses that individual housing modules can be combined to create light curtains with different protective field heights from a single, short base module. The disadvantage of this variant is that each connection point contains an electrical transition that must be sealed against environmental influences. Furthermore, the mechanical stability of this connection is limited, which is why only a few housing modules can be combined and the maximum protective field height of a light curtain constructed in this way is limited.

[0010] Patent US 2014 / 346318 discloses that a circuit board equipped with spacers can be aligned relative to a tube aperture so that the axis of the optoelectronic components (LED / lens) precisely aligns with the axis of the aperture. The circuit board can then be secured in position by laser welding the spacers to the tube. The disadvantage of this approach is that for each light beam in a light grid, the optoelectronic component must be aligned with the corresponding aperture and secured by laser welding. This is very time-consuming and costly. Furthermore, each light beam requires two spacers, which are required for the laser welding. This also leads to high manufacturing costs.

[0011] TASK

[0012] It is therefore an object of the present invention to propose an alternative photoelectric sensor, in particular a light grid, with a simple and cost-effective connection between the optical modules and the housing, which has increased vibration and shock resistance and can be produced with minimal mechanical stress on the optical modules and the housing. Furthermore, the sealing of the housing should be as effective as possible.

[0013] DESCRIPTION

[0014] The problem is solved by a photoelectric sensor having the features of patent claim 1.

[0015] The photoelectric sensor, in particular a light grid, comprises an elongated housing and an optical module arranged in the housing. Transmitting and / or receiving elements are arranged at a distance from one another on the optical module, and the optical module is connected to the housing via contact points, wherein the contact points are planar. The optical module and the housing comprise plastic. According to the invention, at least some of the contact points are designed as welded connections, wherein the housing forms a welded connection with the optical module. The welded connection between the housing and the optical module is formed by laser transmission welding.

[0016] The housing serves as a stabilizing element and protects the photoelectric sensor's optical module from external influences. The welded joint creates a secure connection between the housing and the optical module located within. The advantage is that the optical modules are initially positioned by inserting them into the housing and then firmly connected to the housing in a second step.

[0017] This enables a simple assembly process on the one hand and creates a solid connection between the two components of the photoelectric sensor on the other, which significantly increases its resistance to vibration and shock loads.

[0018] The housing can be described as a device housing because it serves to accommodate an optics module, meaning that the optics module is completely enclosed by the housing. Thus, the optics module is completely enclosed by the housing in the circumferential direction.

[0019] Since the components touch at the contact points, a temperature increase in one of the two components also causes the other component to experience a temperature increase. This raises the temperature of the material at the irradiated points to its melting point. As a result, the material of both components melts at the irradiated contact point, and after cooling, a bond is formed. This process is called laser transmission welding.

[0020] Laser transmission welding offers the advantage over ultrasonic welding in that the energy can be applied to the weld without contact. Irradiating a contact point with a laser beam from the outside is sufficient to create a solid weld. By comparison, in an ultrasonic welding process, the sonotrode used to generate the ultrasonic waves is in contact with the component to be welded. Therefore, the components to be welded, i.e., the joining partners, are exposed to a high joining force during the welding process. In laser transmission welding, however, the energy used to create the connection between the components or to weld both components together is applied without contact.

[0021] The contactless connection process has the advantage that no external compressive force is required to act on the joint. This allows for welding of contact points that cannot absorb the joining force of an ultrasonic wave welding sonotrode, or that are located in a closed system. Furthermore, there is no risk of previously aligned joining partners shifting due to the applied joining force.

[0022] The simple design of the housing and the use of plastic for the main components of the photoelectric sensor result in low manufacturing costs. The cost of purchasing plastic is comparatively low.

[0023] In a preferred embodiment, at least in the area of ​​the contact points, either the housing is permeable to infrared rays and the optical module is absorbing infrared rays, or the housing is absorbing infrared rays and the optical module is permeable to infrared rays. The contact points result from contact points or contact surfaces between the housing and the optical module. If one of the two components absorbs infrared rays in the area of ​​the contact point, irradiation of the contact point with infrared laser beams leads to a local temperature increase, which during the manufacturing process continues until the plastic material at the irradiated point melts.

[0024] Advantageously, the contact points of the optics module and the housing each comprise a compatible plastic, particularly thermoplastics, more preferably polycarbonate. "Compatible" in the context of the present invention means that the plastics can be joined together by laser beam welding. By fusing the plastic materials of the two components, a particularly robust welded joint can be created. If identical plastic materials are used, the optics module and the housing experience the same thermal expansion during the welding process and later during operation due to their identical thermal expansion coefficients, so that no stresses arise in the welds due to thermal expansion.

[0025] In a further preferred embodiment, the plastic material of at least one of the two components is mixed with an infrared-absorbing additive at the intended contact points between the optical module and the housing. The infrared-absorbing material is advantageously evenly distributed throughout the plastic. Mixing the plastic with such an additive eliminates an additional step after component production, since the additive is already integrated into the plastic at the contact points.

[0026] In a further preferred embodiment, the optics module comprises a support body on which a circuit board with the transmitting and receiving elements is arranged. Thus, the transmitting and receiving elements are arranged on a circuit board, with the support body, as a component of the optics module, having, among other things, the task of accommodating the circuit board. The circuit board can be connected to the support body in a form-fitting or force-fitting manner. It is also conceivable for a circuit board to be arranged on multiple support bodies.

[0027] The support body and the housing are advantageously made of a compatible thermoplastic material. This allows a welded connection between the housing and the support body to be created. In this embodiment, the support body is the component of the optical module that is made of a thermoplastic material compatible with the housing. Creating the welded connection with the housing via the support body enables the use of a modular design of the optical module. Additional devices can be provided as components of the optical module, which can perform additional functions without having to meet the requirement of being made of a compatible plastic.

[0028] Such additional devices can include, among others, a lens or a diaphragm device. Preferably, lens and / or diaphragm devices are provided on the support body opposite the transmitting or receiving elements. The lens device includes, among other things, lenses whose function is to scatter or focus the incoming or outgoing rays. The diaphragm device serves to limit the amount of light emitted by the transmitting elements or received by the receiving elements. The diaphragm device ensures the resolution of the safety light grid. The resolution of the safety light grid determines the size of the smallest detectable object. Since the optical module can include a diaphragm and lens device, the welded connection between the optical module and the housing can also be created via the diaphragm and / or lens device.It is conceivable that two support bodies in contact at their ends are connected via a lens or aperture device. For example, the aperture device can have vertically projecting positioning pins on the side facing the support body, which can be inserted into recesses provided for this purpose on both support bodies.

[0029] Preferably, at least the support body and the housing are made of polycarbonate. Polycarbonate exhibits higher impact resistance than alternative plastics such as PMMA.

[0030] Conveniently, the transmitting elements each comprise light-emitting diodes, and the receiving elements each comprise photodiodes. Light-emitting diodes and photodiodes have a high availability.

[0031] The housing preferably has a cylindrical shape, in particular a circular cylindrical shape. The surfaces at the ends of a circular cylindrical housing are annular, and the inner wall of a circular cylindrical housing is formed by a circular cylindrical surface, thereby enabling a press fit to close the openings at the ends of the circular cylindrical housing.

[0032] The housing preferably has a closed cross-section. This means that the housing has no connection or transition point between two components or semi-finished products in the circumferential direction. Alternatively, the outer surface of the housing can also be said to be a single piece. This eliminates the need for a sealing element and increases the stability of the housing.

[0033] The closed-cross-section design of the housing, combined with the laser transmission welding process for creating the connection between the housing and the optics module, results in a controlled introduction of heat to form the welded joint. Laser transmission welding allows the optics modules to be welded to the housing using a peripherally closed housing. Using other welding processes, such as ultrasonic welding, an open housing (U-profile) would be necessary. This is because ultrasonic welding transfers energy via vibrations, and the components to be welded must be firmly clamped. Since the optics module cannot be clamped into a closed housing, ultrasonic welding would cause the optics module to vibrate.This, in turn, precludes the controlled introduction of heat to form a weld between the housing and the optics module. For this reason, the formation of a weld between the housing and the optics module using laser beam welding cannot simply be replaced by ultrasonic welding. Furthermore, a closed housing eliminates the need for an additional joint between two housing parts that would need to be joined and sealed.

[0034] In a further preferred embodiment, the housing comprises an elongated base body forming a receiving space for the optical module, with at least one opening on one long side and a protective screen closing this opening. This represents an alternative design to the cylindrical housing described above. The optical module can be inserted through the opening on the long side or through the front openings at the long ends. The connection between the elongated base body and the protective screen can be either fixed, i.e., inseparable, or detachable. The protective screen is intended to allow the electromagnetic radiation of the transmitting and receiving elements of the photoelectric sensor to pass through.

[0035] The base body is preferably a U-profile with an opening on one long side. The U-profile is characterized by the combination of a stable shape with low material consumption and large capacity. This makes it ideal for use as a base body for the housing. Furthermore, the U-profile simplifies the installation of the optics modules because it is open on one long side.

[0036] The protective screen is advantageously welded to the base body at the edge, preferably by laser transmission welding. The weld creates a solid connection between the base body and the protective screen and preferably forms a watertight seal between these components at the edge of the protective screen to meet protection classes IPX5, IPX7, and IPX9K. In addition, laser transmission welding can help increase production speed and thus reduce manufacturing costs by eliminating the need for additional sealing elements such as O-rings, adhesives, adhesive tape, etc.

[0037] In a further preferred embodiment, end caps are attached to both open longitudinal ends of the housing. The end caps serve to close the openings at the longitudinal ends.

[0038] The end caps are advantageously made at least partially of an infrared-absorbing plastic. Thus, the end caps can also be connected to the housing or the optics module by laser transmission welding. As a result, the interior of the housing is splash-proof. The end caps are preferably bonded to the housing and / or the optics module with a material fit. This bond creates a durable connection between the end caps and the housing or the optics module. The bond between the end caps and the housing and / or the optics module is preferably created by laser transmission welding. The end caps are advantageously attached to the housing or the optics module by laser transmission welding.For a laser transmission welding connection between the end caps and the housing or optical module, either the end caps, the housing or the optical module must absorb infrared rays at least at the contact surfaces.

[0039] Another advantage is that the laser welding process can also be used to create a welded joint around the perimeter of the housing on the front side. Lengths of approximately 2 meters are common for light grids. With such dimensions, the components would be unable to absorb the joining force of an ultrasonic weld, or would require considerable effort.

[0040] The end caps close the two opposing openings of the sensor housing. Preferably, the connection, in particular the weld seam, between the end caps and the housing forms a seal. It is conceivable for the end caps to have a ring shoulder protruding into the interior of the housing, the outer diameter of which corresponds to the inner diameter of the housing. This allows the end caps to be connected to the housing over the entire circumference, creating a welded joint that ensures splash protection. This type of connection has the advantage that an additional seal between the housing and the end caps is not required. The proposed welded joint thus prevents the ingress of moisture, especially when the photoelectric sensor is exposed to different temperatures during use. Such a connection is also suitable for higher sealing protection classes such as IP69K.

[0041] In a further preferred embodiment, two or more optical modules can be coupled to each other at the end face. This has the advantage that sensor devices with different protective field heights can be manufactured. The sensor housing can therefore be several times the length of a single optical module.

[0042] Preferably, the transmitting and / or receiving elements of all optical modules in the housing are directed in the same radial direction of the cylindrical housing. For light grids, it is important that all beams of the photoelectric sensor run exactly parallel to ensure the best possible alignment of the light grid.

[0043] In a further preferred embodiment, the optical module has a first plug connection at one longitudinal end and a second plug connection at its opposite longitudinal end, wherein the first and second plug connections can be coupled to one another. It is important that the plug connection between two optical modules ensures precise, play-free alignment, and that the optical modules cannot rotate about their longitudinal axes, so that the beam axes of the optical modules are aligned parallel.

[0044] Preferably, the first connector is a male connector and the second connector is a female connector. The male-female connection provides a reliable and cost-effective way to connect two or more optical modules.

[0045] The end cap preferably has a plug connection that can be coupled to the plug connection of the terminal optics module. This prevents relative rotational movement between the optics module and the adjacent end cap around the longitudinal axis of the housing. Due to the coupling of the end cap to the optics module, the alignment of the optics module can be adjusted before welding by rotating the coupled end cap. The end cap can, for example, have a positioning mark that defines the welding position of the optics module in the machine holder or with which the correct welding position of the optics module can be easily determined visually by a specialist.

[0046] In a further preferred embodiment, the photoelectric sensor comprises a mounting device for attaching the photoelectric sensor to a base. Advantageously, the mounting device is connected to the housing of the photoelectric sensor by laser transmission welding, which in turn leads to low production costs.

[0047] A further aspect of the invention relates to a photoelectric sensor, in particular a light grid, which has an elongated housing and at least two optical modules arranged therein. The photoelectric sensor is characterized in that the optical modules can be coupled to one another at the end by means of a plug-in connection, wherein the optical modules have a plug at the first longitudinal end and a socket at the second end. The plug and socket of the optical modules are shaped and positioned such that the plug of a first optical module can be inserted into the socket of a second optical module, thus preventing relative rotation of an optical module about the longitudinal axis. Such a plug-in connection between two optical modules ensures that these optical modules are always aligned the same after coupling.

[0048] Another aspect of the invention relates to a method for producing a photoelectric sensor comprising an elongated housing and an optical module, wherein the optical module is inserted into the housing, aligned therein, and subsequently connected to the housing by laser transmission welding. Transmitting and / or receiving elements are arranged on the optical module, and the photoelectric sensor preferably serves to form a light grid. Ideally, the elongated housing has an opening at at least one longitudinal end through which the optical module can be inserted into the housing. The optical module is aligned in the housing so that the transmitting and / or receiving elements on the optical module point in the desired direction. The optical module must be in contact with the housing so that laser transmission welding can be used. The contact points between the housing and the optical module serve as welding points.The housing has an opening at at least one longitudinal end. The optical module is preferably inserted through the open longitudinal end of the housing. Using the open longitudinal end eliminates the need for additional openings in the housing, ensuring greater dimensional stability of the housing.

[0049] The opening at the longitudinal end of the housing forms the smallest possible area, which, due to its position at the end of the housing, can be closed relatively easily. Preferably, the opening at the longitudinal end of the housing is closed with an end cap after the optical module has been inserted into the housing.

[0050] The end cap should, if possible, provide a splash-proof seal around the housing, protecting the optics module located within the housing from external environmental influences. The end cap can be welded to the housing or the optics module, preferably using laser transmission welding. The welded connection between the end cap and the housing forms a seal, eliminating the need for a separate component as a seal. This allows the end cap to be connected to the housing or the optics module in the same way as the optics module is connected to the housing, simplifying and reducing the cost of manufacturing.

[0051] After inserting the optics module into the housing, it must be ensured that it is centered within the housing. Support arms on the optics module can be used to assist in this. The optics module preferably has support arms that are in contact with the housing when inserted into the housing and center the optics module within the housing.

[0052] BRIEF DESCRIPTION OF THE CHARACTERS

[0053] The invention is described in more detail below with reference to the accompanying schematic figures. These preferred features can be implemented in any combination, provided they are not mutually exclusive. They show, in a schematic representation not to scale: Figure 1: a three-dimensional partial view of a first photoelectric sensor according to the invention, consisting of a housing and an optical module arranged therein;

[0054] Figure 2: a longitudinal section through the photoelectric sensor of Figure 1;

[0055] Figure 3: a perspective view of the first photoelectric sensor in which the opposite openings of the housing are closed with end caps;

[0056] Figure 4: a front view of the first photoelectric sensor in which the

[0057] end cap is removed;

[0058] Figure 5: a perspective view of several optical modules arranged in a row;

[0059] Figure 6: a perspective view of a second photoelectric

[0060] Sensor with a two-part housing.

[0061] DETAILED DESCRIPTION OF THE FIGURES

[0062] In the following, identical reference numerals refer to identical or functionally identical elements (in different figures). An additional apostrophe may be used to distinguish identical or functionally identical or functionally similar elements in a further embodiment.

[0063] Figure 1 shows a photoelectric sensor 11 according to the invention. The photoelectric sensor 11 comprises a housing 13 and an optics module 15, on which a circuit board 19 with light sources or light sinks is arranged. In the example shown, the housing 13 is transparent and formed by a hollow cylinder. The length of the cylindrical housing 13 is many times greater than its diameter. The optics module 15 is placed within the housing 13. The optics module 15 comprises a support body 17, a lens device 21, a circuit board 19, and an aperture device 22, although the lens device is not visible in this view. The lens device 21 and the aperture device 22 are arranged on the same longitudinal side of the support body, while the circuit board 19 is arranged on the opposite longitudinal sides of the support body 17.In the embodiment shown, the circuit board 19 and the aperture device 21 are not in contact with the housing 13. It is conceivable that the connection between the optical module 15 and the housing 13 is created via the lens device 21, the aperture device 22 or a component specially introduced for this purpose.

[0064] The support body 17 has projections 26 on its longitudinal sides 25, which extend to the housing 13 and create a contact point with it. In the illustrated embodiment, the support body 17 has three contact points 24 per long side. These contact points 24 serve as welding points to connect the support body 17 to the housing 13.

[0065] Support arms 23 are attached to the optics module 15 at irregular or regular intervals along its length. The support arms 23 serve to position the optics module 15 within the housing 13. The support arms 23 protrude vertically from the respective long side 25, so that they are in contact with the housing 13. Although not provided for in the illustrated embodiment, the support arms can also serve as welding points. The other functions of the support arms 23 are discussed further below.

[0066] Figure 2 shows a longitudinal section of the portion of the photoelectric sensor shown in Figure 1. The hollow cylindrical housing 13 forms the outer boundary of the sensor 11. The optics module 15, which includes, among other things, the support body 17, is arranged therein. A circuit board 19 is arranged along one side of the support body 17, with the transmitting or receiving elements 29 of the photoelectric sensor 11 arranged thereon. The beams from the transmitting and receiving elements 29 must pass through the support body 17. For this purpose, continuous recesses 31 are provided in the support body 17 at the level of the transmitting or receiving elements. A lens device 21 is arranged at the end of the recess 31 opposite the transmitting or receiving elements 29. The lens device 21, in turn, is attached to the support body 17 by means of the aperture device 22, which serves as an aperture for the lens device 21 and ensures a desired resolution of the light grid.The aperture device 22 has a plate-shaped structure with positioning pins 28 projecting vertically on one flat side. The support body 17 has recesses for receiving the positioning pins 28 of the aperture device 22. The positioning pins 28 and the recesses in the support body 17 are dimensioned such that when the positioning pins 28 are inserted into the recesses, a frictional connection is created between the support body 17 and the aperture device 22. The length of the aperture device 22 can differ from that of the support body 17. It is possible for several aperture devices 22 to be arranged on one support body 17.

[0067] The hollow cylindrical housing 13 has an opening 32 at each of its longitudinal ends. These openings can each be closed with an end cap 27. In Figure 2, the opening 32 of the hollow cylindrical housing 13 is closed by an end cap 27. The end cap 27 projects with a first region 33 through the opening into the hollow cylinder, so that this region is in contact with the inside of the housing wall. The second region 34 of the end cap 27, which lies outside the housing 13, is attached to the longitudinal end of the housing, so that the end cap 27 and the housing 13 have an annular contact surface. The contact surface in the first region 33 can serve as a welding point. The cylindrical surface as a contact surface in the first region 33 between the end cap 27 and the housing 13 enables the use of laser beams directed perpendicularly onto the housing 13 for laser welding.The contact surface in the second region 34, however, requires the use of laser beams directed at an acute angle to the housing wall for laser welding. By rotating the laser beam source or the housing 13 around its central axis, a fully circumferential weld between the housing 13 and the end cap 27 can be created in a single step.

[0068] Figure 3 shows a photoelectric sensor 11 in its entirety. The housing 13 of the photoelectric sensor is cylindrical. The optical modules are arranged within the housing 13 and are not visible in this figure. End caps 27 are attached to both ends of the cylindrical housing 13. One of the end caps 27' has an opening for a connector 35. The connector 35 forms the interface with another electrical device, so that the information from the photoelectric sensor 11 can be transmitted via the connector 35, for example, to a control unit attached to it. At the same time, the information from the optical module 15 adjacent to the end cap 27 is transmitted to the connector 35 via its circuit board 19. The end caps 27 completely cover the area at the ends of the cylindrical housing 13. The part of the end caps 27 that protrudes beyond the housing 13 is in the shape of an octagonal nut.This enables, among other things, positional orientation between end caps and optical modules and prevents the light grid from rolling away.

[0069] Figure 4 shows an end view of a photoelectric sensor 11, showing the connector plug 35 but not the end cap. The optics module 15 is positioned within the cylindrical housing 13. The optics module 15 is in contact with the housing 13 via the projections 26 on the long sides 25 and via the support arms 23. In the cross-section shown in Figure 4, there are four contact points between the optics module 15 and the housing 13, although in the embodiment shown, only the projections 26 of the optics module are provided as welding points. The support arms 23 serve to position the optics module 15 within the housing 13 until a welded connection is created. The distance between the opposing projections 26 is slightly larger than the inner diameter of the housing 13, so that a press fit is formed between the optics module 15 and the housing 13.The support arms 23 extend approximately perpendicular to the plane formed by the opposing projections 26 and, upon contact with the housing, generate a force in the opposite direction. (?) Even though this force is very small, it helps to fix the optics module 15 in the housing 13 until the welded joint is created.

[0070] One or more printed circuit boards 19 are positively received on the optics module 15. When more than one printed circuit board 19 is used, the electrical connection between adjacent printed circuit boards 19 is established via connecting plugs 37. These are intended to be attached to the printed circuit boards 19.

[0071] The optical module 15 has connectors 39 at one end and sockets at the other end, which create a plug-socket connection. This means that the dimensions and location of the connectors and sockets are selected such that the connectors 39 of one optical module 15 can be inserted into the sockets of another optical module. The sockets are arranged at the same height and width as the connectors 39. This connection prevents all optical modules from twisting relative to one another and ensures that after a connection has been established between two optical modules 15, the transmitters or receivers of all optical modules 15 are aligned in the same direction.

[0072] Figure 5 shows two interconnected optical modules 15, 15'. In the embodiment shown here, the circuit boards 19 are arranged on one longitudinal side of the support bodies 17, 17', while lens devices 21 are arranged on the opposite longitudinal side of the support bodies 17, 17'. An aperture device 22 is attached to the side of the optical module 15 on which the lens devices 21 are arranged. The aperture devices 22 are provided to be attached to the optical modules 15 in such a way that a continuous aperture device 22 is arranged at the transition between each two optical modules 15. Thus, the aperture device 22 arranged on two optical modules 15, 15' ensures that the resolution is also identical across modules. During assembly, the optical modules 15 are brought together in a first step via their plug-socket connection so that the transmitters or receivers of the optical modules 15 are aligned in the same way.For this purpose, the plugs 39 of a first optical module 15 are inserted into the socket of the second optical module. In a second step, the aperture devices 22 are attached to the optical modules so that the lined-up optical modules 15 are connected to form a string of optical modules. The adjacent circuit boards 19 are connected to one another via connecting plugs 37. The connecting plugs form the electronic connection between two circuit boards 19. As an alternative to the embodiment shown in Figure 5, it is also conceivable for an aperture device not to be arranged on two support bodies, but rather for a new aperture device to be arranged at the transition from one support body to the adjacent support body.

[0073] Figure 6 shows a further embodiment of a photoelectric sensor according to the invention. In contrast to the previously shown embodiment, the housing 13 does not have a round cross-section but a rectangular cross-section. The housing 13 is formed from a U-profile 45 and a protective screen 47, wherein the protective screen 47 is arranged on the U-profile 45 in such a way that it closes the opening in the U-profile. The optics module is placed in the housing 13. The optics module 15 can be attached both to the U-profile 45 and to the protective screen 47 of the housing. End caps 27 are also provided to close the openings at both ends of the housing 13 shown here. The end cap 27 has a shape corresponding to the cross-section of the U-profile 45 and can be arranged adjacent to the respective openings in the U-profile 45.While specific embodiments have been described above, it is obvious that different combinations of the embodiments shown may be used, provided that the embodiments are not mutually exclusive.

[0074] LIST OF REFERENCE SYMBOLS:

[0075] 11 Photoelectric sensor

[0076] 13 housings

[0077] 15 Optics module

[0078] 17 supporting bodies

[0079] 19 Circuit board

[0080] 21 Lens device

[0081] 22 Aperture device

[0082] 23 support arms

[0083] 24 contact points

[0084] 25 long sides

[0085] 26 Before jumps

[0086] 27 end caps

[0087] 28 Positioning pins

[0088] 29 Transmitting or receiving element

[0089] 31 Continuous recess on the supporting body

[0090] 32 Opening at the longitudinal end of the housing

[0091] 33 Contact surface in the first area

[0092] 34 Contact surface in the second area

[0093] 35 connector plugs

[0094] 37 PCB connectors

[0095] 39 plugs

[0096] 45 U-profile

[0097] 47 Protective screen

Claims

CLAIMS 1. Photoelectric sensor (11), in particular light grid, comprising - an elongated housing (13) and - an optical module (15) which is arranged in the housing (13), wherein - transmitting and / or receiving elements (29) are arranged at a distance from one another on the optical module (15), - the optical module (15) is connected to the housing (13) via contact points (24), and - the optical module (15) and the housing (13) comprise plastic, characterized in that at least some of the contact points (24) between the optical module (15) and the housing (13) are designed as welded connections and the welded connection between the housing (13) and the optical module (15) is formed by laser transmission welding.

2. Photoelectric sensor (11) according to claim 1, characterized in that at least in the region of the contact points (24) to be formed as welded connections, either the housing (13) is permeable to infrared rays and the optical module (15) is absorbing infrared rays or the housing (13) is absorbing infrared rays and the optical module (15) is permeable to infrared rays.

3. Photoelectric sensor (11) according to one of claims 1 to 3, characterized in that the contact points (24) of the optical module (15) and the housing (13) each comprise a mutually compatible plastic, in particular thermoplastics, more preferably polycarbonate.

4. Photoelectric sensor (11) according to one of claims 1 to 4, characterized in that the plastic material of at least one of the two components the provided contact points (24) of the optical module (15) with the housing (13) are mixed with an infrared radiation-absorbing additive. Photoelectric sensor (11) according to one of claims 1 to 5, characterized in that the optical module (15) comprises a support body (17) on which a circuit board (19) with the transmitting or receiving elements is arranged. Photoelectric sensor (11) according to claim 6, characterized in that the support body (17) and the housing (13) consist of a compatible, thermoplastic material and the welded connections are made between the housing and the support body (17). Photoelectric sensor (11) according to claim 6 or 7, characterized in that lens (21) and / or diaphragm devices (22) are provided on the support body (17) opposite the transmitting or receiving elements (29).Photoelectric sensor (11) according to one of claims 6 to 8, characterized in that at least the support body (17) and the housing (13) are made of polycarbonate. Photoelectric sensor (11) according to one of claims 1 to 9, characterized in that the transmitting elements each comprise light-emitting diodes and the receiving elements each comprise photodiodes. Photoelectric sensor (11) according to one of claims 1 to 10, characterized in that the housing (13) has a cylindrical shape, preferably a circular cylindrical shape. Photoelectric sensor (11) according to one of claims 1 to 11, characterized in that the outer surface of the housing (13) is made in one piece. Photoelectric sensor (11) according to one of claims 1 to 11, characterized in that the housing (13) comprises an elongated base body forming a receiving space for the optical module, with at least one opening on one long side and a protective screen (47) closing at least this opening. Photoelectric sensor (11) according to claim 13, characterized in that the base body is a U-profile (45) provided with one or more openings on one long side. Photoelectric sensor (11) according to claim 13 or 14, characterized in that the protective screen (47) is welded to the base body at the edge, preferably by laser transmission welding. Photoelectric sensor (11) according to one of claims 13 to 15, characterized in that the welded connection between the base body and the protective screen (47) forms a splash-proof connection.Photoelectric sensor (11) according to one of claims 1 to 16, characterized in that end caps (27) are attached to both open longitudinal ends of the housing (13). Photoelectric sensor (11) according to claim 17, characterized in that the end caps (27) are made at least partially of an infrared-absorbing plastic. Photoelectric sensor (11) according to claim 17 or 18, characterized in that the end caps (27) are attached to the housing (13) and / or to the optics module (15) in a material-to-material manner. Photoelectric sensor (11) according to one of claims 17 to 19, characterized in that the end caps (27) are attached to the housing (13) and / or to the optical module (15) by means of laser transmission welding. Photoelectric sensor (11) according to one of claims 17 to 20, characterized in that the connection, in particular the weld seam, between the end caps (27) and the housing (13) forms a seal. Photoelectric sensor (11) according to one of claims 1 to 21, characterized in that two or more optical modules (15) can be connected to one another at their ends. Photoelectric sensor (11) according to one of claims 1 to 22, characterized in that the transmitting and / or receiving elements (29) of all optical modules (15) in the housing (13) are directed in the same radial direction of the cylindrical housing.Photoelectric sensor (11) according to one of claims 1 to 23, characterized in that the optical module (15) has a first plug connection at one longitudinal end and a second plug connection at its opposite longitudinal end, wherein the first and second plug connections can be coupled to one another. Photoelectric sensor (11) according to claim 24, characterized in that the first plug connection is designed as a plug (39) and the second plug connection as a socket. Photoelectric sensor (11) according to claim 24 or 25, characterized in that the end cap (27) has a plug connection which can be coupled to the plug connection of the terminal optical module (15). Photoelectric sensor (11) according to one of claims 1 to 26, characterized in that the photoelectric sensor (11) comprises a mounting device for fastening the photoelectric sensor (11). Method for producing a photoelectric sensor (11) comprising an elongated housing (13) and an optical module (15) arranged in the housing, wherein - transmitting and / or receiving elements (29) are arranged on the optical module (15), - the optical module (15) is inserted into the housing (13) and - is aligned therein, characterized in that the optics module (15) is connected to the housing (13) by laser transmission welding. Method according to claim 28, characterized in that the optics module is inserted through an open longitudinal end of the housing. Method according to claim 29, characterized in that the open longitudinal end is closed with an end cap after insertion of the optics module. Method according to claim 30, characterized in that the end cap is welded to the housing or the optics module, preferably by means of laser transmission welding. Method according to one of claims 28 to 31, characterized in that the optics module has support arms which are in contact with the housing upon insertion into the housing and center the optics module in the housing.

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