Processing system

A processing system for plate-like objects is provided, with an exposure device and an object carrier with an object carrier surface for receiving the object. The exposure device and the carrier are movable relative to one another, such that the exact position of the object relative to the carrier is determinable. An edge detection device is provided which comprises at least one edge illumination unit having an illumination area, within which an object edge located in the respective object edge area has light directed onto it from the side of the carrier. At least one edge image detection unit is provided on a side of the object located opposite the carrier, the edge image detection unit imaging an edge section of the object edges located in the illumination area as an edge image, such that the respective edge image is detectable in its exact position relative to the carrier.

BACKGROUND OF THE INVENTION

The invention relates to a processing system for plate-like objects, in particular an exposure system for plate-like objects, comprising an exposure device and an object carrier with an object carrier surface for receiving the object, wherein the exposure device and the object carrier are movable relative to one another for the purpose of exposing the object.

Processing systems of this type are known.

Such a processing system could be used, for example, for the laser treatment of plate-like objects.

It is, however, also conceivable to use such a processing system as exposure system for plate-like objects, in particular for plate-like objects with a photosensitive coating, wherein structures can be generated in the photosensitive coating by way of lithography.

The problem with such processing systems is that when the plate-like objects are intended to be placed on the object carrier or processed on both sides, in particular exposed, the object has to be positioned on the object carrier in a defined manner each time.

The object underlying the invention is, therefore, to improve a processing system of the generic type in such manner that the position of the plate-like object relative to the object carrier can be determined exactly.

SUMMARY OF THE INVENTION

This object is accomplished in accordance with the invention, in a processing system of the type described at the outset, in that an edge detection device is provided for the purpose of detecting the position of the object on the object carrier and comprises at least one edge illumination unit arranged in the object carrier beneath the object carrier surface, that the edge illumination unit has an illumination area in at least one section of an object edge area and within said illumination area an object edge located in the respective object edge area has light which is radiated areally directed onto it from the side of the object carrier, and that at least one edge image detection unit is provided at a distance from the object carrier surface on a side of the object located opposite the object carrier and images an edge section of one of the object edges located in the illumination area onto an image surface as edge image and that the respective edge image can be detected in its exact position relative to the object carrier with the at least one edge image detection unit.

The advantage of the solution according to the invention is to be seen in the fact that with this solution it is possible in a simple manner to detect the position of the object edges on the object carrier exactly and, therefore, to align the structures generated on the object exactly relative to the object edges.

This is advantageous, for example, in the case of complex structures, wherein the structure on one surface of the object must match the structure on the other surface of the object in order to be able, for example, to link the structures to one another.

The precision of the detection of the object edges may be improved, in particular, in that the optical device of the at least one edge image detection unit is designed as a telecentric lens.

Such a telecentric lens has the advantage that it images onto the image surface only beams which extend parallel to the optical axis of such a lens and so, as a result, an exact silhouette of the respective object edge can be imaged onto the image surface.

In order to avoid faulty edge images as a result of edge surfaces which extend at an angle, it is preferably provided for an optical axis of the telecentric lens to deviate at the most by 5° from a line which is vertical relative to the object carrier surface.

As a result, the edge image on the image surface is imaged by beams which all extend essentially in a vertical direction relative to the object carrier surface and so even an inclined edge surface of an object edge always supplies the same silhouette.

The image surface of the edge image detection unit could, for example, be an image surface, in which an operator of the processing system can recognize the position of the object edge in the edge image immediately with his eyes or with an optical device.

One particularly favorable solution provides, however, for the image surface to be the image surface of an image sensor, by means of which the edge image may be detected.

Such a sensor could be any type of optical sensor.

In order to be able to determine the position of the object edge exactly, it is favorable when the image sensor is a camera image sensor so that the position of the object edge can be detected on the camera image sensor with the resolution thereof.

In principle, the edge image detection unit could be designed such that it detects the associated illumination area completely.

Such a design of the edge detection area would, however, require a correspondingly complicated optical device.

In order to be able to construct the edge image detection unit with as simple means as possible, it is preferably provided for the optical device of the at least one edge image detection unit to have a detection area which has a smaller surface extension than the respective illumination area.

As a result, it is possible to use an inexpensive optical device.

In principle, when the position of the respective object edge is determined approximately and the blurring of the positioning of the respective object edge is located within the detection area, the edge image detection unit can be positioned stationarily relative to the illumination area.

However, in order to be able to operate with large differences with respect to the position of the object edges for as long as they are located in the respective illumination area, it is preferably provided for the detection area and the illumination areas to be movable relative to one another. As a result, it is possible to detect the entire illumination area with the detection area, but successively, in a simple manner by way of the relative movement of detection area and illumination area.

In this respect, it is provided, in particular, for the detection area to be movable at least to such an extent until the object edge is located in the detection area.

One particularly favorable solution provides for the detection area to be movable in a direction transverse to the respective object edge to be detected.

Alternatively thereto, one favorable solution provides for the detection area to be movable in the direction of the respective object edge to be detected.

Movement of the detection area could be brought about, in principle, by way of optical deflection elements but these would have the disadvantage that, as a result, blurring would occur in the area of the detection of the object edges.

For this reason, one advantageous solution provides for the at least one edge image detection unit and the object carrier to be movable relative to one another in at least one direction.

In addition, in order to open up the possibility of detecting object edges in several illumination areas with one edge image detection unit, it is preferably provided for the at least one edge image detection unit and the object carrier to be movable relative to one another in two directions which extend transversely to one another.

With respect to the illumination areas provided, no further details have been given in conjunction with the preceding explanations concerning the individual embodiments.

With one solution it would be conceivable to provide a very large illumination area, in which several object edges can be detected.

In order to configure the detection of the object edges as simply as possible, it is preferably provided for the object carrier to have an illumination area for each object edge for directing light onto this object edge.

As a result, each object edge is preferably provided with an illumination area created specifically for it.

Alternatively thereto, another advantageous solution provides for several, for example, two object edges to have light directed onto them and be monitored in one illumination area so that, as a result, the number of illumination areas can be reduced and the detection of the object edges can be brought about more quickly.

The number of illumination areas can vary with a view to the number of object edges to be detected.

In order to ascertain the position of the object relative to the object carrier it could be sufficient to detect two object edges and, in particular, to detect the course of the two object edges relative to the object carrier.

In the case of as precise a detection as possible of the position of the object relative to the object carrier, it is, however, advantageously provided for three object edges of the object to be detected with the processing system according to the invention.

Particularly when three object edges are detected, it would, in theory, be sufficient to detect one point in the region of each object edge.

The accuracy of the edge detection unit according to the invention may, however, be enhanced considerably when the at least one edge image detection unit records at least one edge section of the object with the respective edge image.

This means that the respective edge image does not detect and record merely one point of the object edge but rather an entire edge section, i.e. a plurality of points along an object edge.

In this respect, it is favorable, in particular, when the at least one edge image detection unit records a course of an edge section of the object with the respective edge image.

This means that all the image points located along the edge section can be detected and so it is possible to subsequently recognize this edge section again on account of its particular course, i.e., for example, on account of its course not extending in a straight line and, therefore, use this for the exact positioning or for the exact measurement of the position of the object relative to the object carrier.

Such a course of an edge section therefore results not only in information on the position of the edge section in one spatial direction but rather in two spatial directions, i.e. in a plane.

Particularly when the courses of several edge sections of several object edges are detected, it is possible to improve the precision of the detection of the position of the object relative to the object carrier considerably, as a result, since a two-dimensional detection of the course of an edge section is possible with each course of the edge section.

One particularly favorable solution provides for the stored course of the edge section to be used for recognizing this edge section again once the object has been placed in position again and for the precise detection of the position of the object.

Such a solution has the great advantage that when the same object is again placed on the object carrier, either after turning the object over or after temporarily removing it and placing it in position again in the same orientation, the position of this object relative to the object carrier can be detected even more exactly as a result of the edge section being recognized again and so the relative positional accuracy can be improved even further, in particular in the case where the same objects are placed back on the object carrier, as a result of this re-recognition of the edge sections on account of the two-dimensional course which can be detected in the case of several edge sections and, therefore, on account of overdetermined position information for the object.

With respect to the design of the illumination unit, no further details have so far been given.

In principle, at least one light source is sufficient to emit the areal light.

The light emitted preferably has a wavelength which is in the red or close infrared spectral range in order not to trigger any photochemical processes in the photosensitive layer.

One advantageous solution provides for the illumination unit to have a diffuser and at least one light source directing light onto it for the purpose of illuminating the respective illumination area.

Such a diffuser having light directed onto it by light sources has the great advantage that, as a result, a very even intensity and, in particular, a diffuse radiation is available which makes the recognition of the object edge or the edge section in the edge image easier, in particular in an automatic manner, since the gradient between the part of the detection area not covered by the object and the covered part of the detection area is essentially always the same irrespective of the position of the object edge in the illumination area and the radiation detected by the edge image detection unit has essentially the same intensity irrespective of the location of the illumination area, in particular also on account of the diffuse radiation.

One particularly simple way of integrating the illumination unit into the object carrier provides for the light sources and the diffuser to be integrated into the object carrier.

With respect to the design of the object carrier, no further details have so far been given.

One advantageous solution, for example, provides for the object carrier to have an object carrier plate forming the object carrier surface and for the light from the illumination unit to pass through the object carrier plate.

As a result, it is possible to provide a continuous object carrier surface, on which to place the object, which is not affected by the illumination unit and so no inaccuracies with respect to the positioning of the object on the object carrier surface occur as a result of the illumination unit itself.

In this respect, the diffuser could be arranged beneath the object carrier plate.

It is, however, particularly favorable when the object carrier plate acts as an optical diffuser, i.e. represents the optical diffuser in addition to receiving the object.

In this respect, it is particularly favorable when the light sources illuminating the diffuser are arranged in a base member bearing the object carrier plate, are, in particular, integrated in this base member so that, as a result, no additional attachments on the object carrier are required.

Additional features and advantages of the invention are the subject matter of the following description as well as the drawings illustrating one embodiment.

DETAILED DESCRIPTION OF THE INVENTION

A first embodiment of an exposure device according to the invention, illustrated inFIG. 1, comprises a machine frame which is designated as a whole as10and has two longitudinal guides12,14which are arranged at a distance from one another and on which an object carrier designated as a whole as20is guided for movement in a first direction designated, for example, as X direction.

The object carrier20has an object carrier surface22, on which objects30can be placed which comprise, for example, as illustrated inFIG. 2, a substrate32which is coated on both sides with photosensitive layers341and342, wherein structures36can be generated in the photosensitive layers341and342by way of photochemical conversion of the respective photosensitive layer34.

These structures36are, for example, structures which cover a copper layer381and382on the substrate32and so the copper layer381and382on the substrate32can be removed, for example, subsequently within the scope of an etching process at those points, at which it is not covered by the structures36, while the copper layer remains only in those areas, in which it is covered by the structures36.

The production of the structures36in the photosensitive layer34is brought about by an exposure device which is designated as a whole as40inFIG. 1and is arranged on a bridge42which is seated, for its part, on the machine frame10, wherein any relative movement between the exposure device40and the object30is brought about in that the object carrier20at least can be moved in the X direction relative to the exposure device40and so the X direction represents a direction of feed44during the exposure of the object30and, where applicable, the exposure device40is held on the bridge42so as to be movable in a Y direction, as well.

Such an exposure device is described, for example, in WO 2008/071347 A, to which reference is made in full with respect to its description.

If the object30, as illustrated inFIG. 2, comprises a substrate32which is coated on both sides with a photosensitive layer34, it is necessary to turn the object30after exposure of one of the photosensitive layers, for example exposure of the photosensitive layer341, in order to expose the photosensitive layer on the opposite side, for example the photosensitive layer342.

In this case, it is, however, necessary to ensure that the structures361of the photosensitive layer341and the structures36exposed in the photosensitive layer342match exactly in order to avoid any offset.

It is, therefore, necessary to detect the position of the substrate30on the object carrier20exactly in order to position the structures36in exact alignment in relation to the respective object edges52,54and56,58of the object30.

Normally, the respective object edges52,54and56,58run parallel to one another but deviations from an axial parallelism can, however, also occur and deviation from an exactly straight-lined course of the object edges52,54and56,58can occur.

In order to be able to detect the object edges52,54,56,58on the object carrier20, object edge areas62,64,66, within which the object edges52,54and56of the objects30are located when they are of normal sizes, are defined on the object carrier20, as illustrated inFIG. 3, and an edge detection device60is provided.

In this respect, the object edge area66is selected such that the same object edge56, which runs transversely to the direction of feed44, is always located in it, irrespective of whether the photosensitive layer341or342is intended to be exposed.

This means that the object edge area66covers the object edge56of the object30, which extends transversely to the direction of feed44, in both positions.

The object edge areas62and64are selected such that the object edges52and54, respectively, which extend parallel or at an angle to the direction of feed44, are located in them, wherein in the one position the object edge52is located in the object edge area62and the object edge54in the object edge area64and in the position turned through 180° the object edge54is located in the object edge area62and the object edge52in the object edge area64.

The detection of the object edges56or52and54in the object edge area66or62and64, respectively, is brought about optically, namely, on the one hand, by way of illumination areas76,72and74which are provided in the object carrier20and extend over at least part of the respective object edge areas.

For example, the illumination area76is located symmetrically to a central axis78of the object carrier20which extends parallel to the direction of feed44and intersects it while the illumination areas72and74likewise extend transversely to the central axis78but at a distance from it and, in addition, are arranged at a distance from the illumination area76in the direction of the central axis78.

The distance of the illumination areas72and74from the illumination area76depends on the minimum extension of the possible objects30in the direction of the central axis76and is preferably slightly shorter than the minimum extension of the possible objects30in the direction of the central axis78proceeding from the object edge area66.

The illumination areas76,72and74are partially covered by the object30which is located on the object carrier20and illustrated by dotted lines inFIG. 3and so the object30intersects the illumination area76with its object edge56and the illuminations areas72and74with its object edges52and54and, consequently, the object edge56is backlit by the illumination area76and the object edges52and54are backlit by the illumination areas72and74and so it is possible to take an edge image of the object edges56or52and54located in the illumination areas76,72and74, namely of the respective edge sections86or82and84which are located within the illumination areas76or72and74.

Edge images are taken, as illustrated inFIGS. 4 and 5by way of example on the basis of the edge sections82and84, by edge image detection units92and94which are illustrated inFIGS. 4 and 5and which, as illustrated inFIG. 1, are held, for example, on a bridge96which is seated on the machine frame10and are displaceable in a direction Y which extends transversely to the X direction, preferably at right angles to it, wherein the positions of the edge image detection units92and94relative to the bridge96can be detected each time by distance measuring systems102and104.

As illustrated inFIG. 6, each of the edge image detection units92,94comprises an optical device110with a telecentric lens111which, as a result of an aperture diaphragm, causes only beams which are parallel to an optical axis114to be imaged onto an image surface116of an image sensor118from a detection area108which is located in the respective illumination area, for example the illumination area72.

The image sensor118is designed, for example, as a type of sensor such as that used in cameras.

As a result, the edge image120which shows the edge section82in the case illustrated inFIG. 6, appears on the image surface116, as illustrated inFIG. 7, namely not only the position thereof but also its course.

The edge image120of the edge section84which is illustrated inFIG. 8can be generated in the same way with the edge image detection unit94.

The optical axis14and, therefore, the radiation which is imaged onto the image surface116by the optical device110operating as a telecentric lens, runs at right angles to the object carrier surface22and so edge surfaces122and124, respectively, which extend at an angle to the object carrier surface22do not result in any falsification since, when the object30is turned through 180°, the edge section84with the edge surface124results, as is shown by a comparison ofFIGS. 5 and 9, in the same edge image120but turned through 180° without the edge surface124, which extends at an angle to the object carrier surface22, affecting the edge image obtained which is, however, turned through 180°, as illustrated inFIG. 10.

With the solution according to the invention, it is not the position of individual points of the respective edge section82or84which is determined in order to evaluate and determine the position of the object30on the object carrier20but rather the position of the entire edge image of the edge section82or84in the Y direction and by determining the position of the edge section82or84prior to turning the object30and after turning the object30, the position of the object30on the object carrier20prior to turning and after turning may be determined exactly in Y direction.

In order to be able to take measurements of the positions of the edge sections82and84in the Y direction relative to the object carrier20which are as exact as possible, the object carrier20is also provided with a reference mark130, to which each of the edge image detection units92and94can travel and the edges of which, which are likewise backlit, can be detected by the edge image detection units92and94in the same way as that described in conjunction with the edge sections82and84.

The position of the edge section86can also be detected in the same way, wherein for this purpose one of the edge image detection units92and94or both edge image detection units92and94will be positioned over the illumination area76as a result of travel in Y direction in order to detect either the position of the entire edge section86or parts of the edge section86in X direction and produce edge images120for this.

The evaluation of the position of the edge sections82,84and86is preferably brought about by a control140for the exposure device40which is in a position to determine the position and the course of the respective edge sections82,84,86in the respective directions X and Y from the edge images120and, on account of this position determination, to control the exposure of one342of the photosensitive layers relative to the other one341of the photosensitive layers in an exactly adjusted manner so that the structures to be generated in the two photosensitive layers341,342are also positioned exactly relative to one another.

In order to obtain as even a brightness as possible in the respective illumination areas76,72,74, edge illumination units150are provided, as illustrated inFIGS. 4 and 5by way of example, and they have individual light sources152which are arranged in one or more rows next to one another and, in addition, a diffuser154is provided between the individual light sources152and this scatters the light from the rows of light sources152such that a diffuse and, therefore, largely even light with respect to its brightness is present on a side of the diffuser154facing the respective illumination area, for example, the illumination area72, wherein in each point of the respective illumination area72the light is radiated in all directions, of which only the beam directions extending at right angles to the object carrier surface22are selected for the purpose of generating the respective edge image120.

In this respect, the light sources152are preferably formed from semiconductor diodes which are arranged in one or several rows offset relative to one another in order to direct light onto the diffuser154in as uniform a manner as possible, as illustrated inFIG. 4,5or9.

The light sources emit light, for example, in a wavelength in the red or close infrared spectral range in order to avoid any exposure of the photosensitive layers34which leads to a photochemical conversion in them.

The edge detection device60according to the invention therefore comprises one or more edge illumination units150which are preferably integrated in the object carrier20as well as the edge image detection units90and92which are held on the machine frame10.

For the purpose of generating the edge images120, the edge image detection units92and94as well as the edge illumination units150are, however, movable relative to one another in order to be able to detect the respective edge images of the object edges52,54,56and evaluate them.

In the embodiment illustrated, the edge image detection units92and94are guided on the bridge96for movement in the Y direction relative to the machine frame while the edge illumination units150are movable relative to the machine frame in the Y direction with the object carrier20.

It is, however, possible in general to obtain a relative movement of the edge image detection units94and the edge illumination units150relative to one another in other ways in that either the edge image detection units92,94or the edge illumination units150are movable in two directions extending transversely to one another.

The movement of the edge image detection units92and94and the edge illumination units150relative to one another is brought about in a manner controlled via the control140, to which the position of the edge illumination units150in the object carrier20is specified, so that the control140is able to position the respective edge illumination units150, which are associated with the illumination areas76,72and74, such that they can be detected by the edge image detection units92,94, wherein the respective illumination area76,72,74is imaged onto the respective image surface116of the image sensor118.

As a result of the fact that the detection areas108have a smaller surface extension than the illumination areas76,72,74, it is necessary to always move the edge image detection units92,94, controlled by the control140, such that in each edge image120generated the respective edge section82,84,86to be measured is located approximately in the center of the edge image.

As a result of the relative position of the edge image detection unit92,94and the respective illumination area76,72,74on the object carrier20specified to the control140, the position of the respective edge section82,84,86in the respective edge image120can be evaluated exactly since a focused, bright-dark contrast is present at it.

As a result, the position of the object30on the object carrier20can be determined exactly by the edge detection device60according to the invention prior to any exposure of the respective photosensitive layer341or342and, therefore, the exposure of the respective photosensitive layer can be corrected exactly in accordance with the position of the object edges52,54,56.

In order, in particular, to improve the precision of the detection of the position of the object30relative to the object carrier20when the object30is turned through 180° so that the flat side previously located on top now lies on the object carrier surface22and the flat side previously lying on the object carrier surface22now faces the exposure device40, the edge images120can be stored in the control with the respective course of the edge sections82,84,86so that this edge section82,84,86, after turning, can be found again on account of its course and can be brought into congruence with the course of the edge section detected prior to turning, which results in greater precision during the determination of the position of the object30after turning in relation to the position of the object30prior to turning, relative each time to the object carrier20.

In a second embodiment of a processing system according to the invention, the respective edge illumination unit150is, as illustrated inFIG. 11, integrated into the object carrier20, wherein the object carrier20comprises a base member162and an object carrier plate164resting on the base member162, wherein the object carrier plate164is designed, for example, as a ceramic plate which, for its part, forms the object carrier surface22on its side facing away from the base member162.

The edge illumination unit150is, for example, integrated into the base member162such that the diffuser154is formed by the object carrier plate164, which therefore acts, for its part, as an optical diffuser, and is seated on the base member162and has light directed onto it by the light sources152designed as light diodes from its side facing away from the object carrier surface22, wherein the light sources152are formed, for example, by two or more rows of light diodes seated next to one another.

The light diodes152are thereby seated in a recess166in the base member162which penetrates the base member162as far as its underside168, wherein the recess166is, however, closed by a cover plate170terminating with the underside168.

As for the rest, reference is made in full to the comments on the first embodiment with respect to all the additional features of the second embodiment.

In a third embodiment, illustrated inFIG. 12, the optical device110′ comprises a telecentric lens111′ on both sides, with which the aperture opening112gives rise to beams parallel to the optical axis114both in the object space and in the image space, i.e. uses only these beams for the imaging and so in contrast to the first embodiment an improved telecentric behavior is present.

As for the rest, the third embodiment operates in the same way as the preceding embodiments and so reference is made in full to the preceding embodiments with respect to the remaining features.

In a fourth embodiment of an exposure system according to the invention, illustrated inFIGS. 13 to 15, the object edge areas62and64as well as66are arranged, as illustrated, for example, inFIG. 14on an enlarged scale, such that they overlap within illumination areas72′ and74′ so that edge sections82and86aof the object edges52and56can be detected by means of the illumination area72′ and edge sections84and86bof the object edges54and56can be detected by means of the illumination area74′.

The object edges52,54and56are likewise detected by the edge image detection units92and94which are movable at least in the Y direction, preferably also in the X direction, in order to use the detection areas108located within the respective illumination areas72′ and74′ for detecting the edge images120of edge sections82and84as well as86aand86b.

In the simplest case, as illustrated inFIGS. 16 and 17, an edge image of the edge section82can be recorded by the edge image120′1and subsequently an edge image of the edge section86aby the edge image120′2.

For this purpose the detection area108is displaced by moving the edge image detection unit92to such an extent that it detects, first of all, for example, only the edge section82but not the edge section86aand subsequently, as a result of travel in X direction, the edge section86ais detected during travel of the detection area108in Y direction.

It is, however, also possible, as illustrated inFIG. 18, to record both the edge section82and the edge section86aat the same time with only one edge image120″ and, therefore, to determine the position of the object30with its edge sections82and86aby way of a one-time positioning of a detection area108both in X direction and also in Y direction, wherein such a determination is also brought about for the edge section84and the edge section86bin order to ascertain the alignment of the object30with great accuracy.

As for the rest, the fourth embodiment operates in the same way as the preceding embodiments and so reference is made in full to the preceding embodiments with respect to the remaining features.