Printing system comprising a conveyor belt

Abstract

The invention relates to a printing system (1) for printing on substrates (S), in particular flat substrates, comprising a printing device (3), in particular a doctor-blade apparatus, which has an image carrier (15), in particular exchangeable image carrier, and comprising a conveyor device (6) for supplying substrates (S) to be printed on to, or removing same from, a printing position underneath the image carrier (15), the conveyor device (6) having a conveyor belt (5) which has a support face (7) for supporting the substrates (S). A control apparatus (16) is provided for identifying the orientation and / or position of the conveyor belt (5) relative to the image carrier (15).

Description

[0001] DESCRIPTION

[0002] Printing system with conveyor belt

[0003] The present invention relates to a printing system for printing, in particular, planar substrates, comprising a printing device, in particular a squeegee device, which has a printing template that is in particular interchangeable, and a transport device for feeding and removing substrates to be printed to or from a printing position below the printing template, wherein the transport device has a conveyor belt which has a support side for placing the substrates.

[0004] Printing systems of the type mentioned above are already known in the art. For printing on flat substrates, such as wafers, printed circuit boards, or solar cell modules, it is known to print them with a printing compound, which is often electrically conductive. To apply the printing compound, doctor blades are used that press the compound through a printing template, designed as a printing screen or stencil, onto the substrate. To optimize the cycle time of such a printing system, it is also known to provide an automated transport device that automatically moves the substrates to the printing position under the printing template and removes them again after printing. Transport devices are also known that include a conveyor belt, in particular an endless belt, which has a support surface for placing the substrates.The support surface is positioned opposite the printing template in the printing position, so that the substrates resting on it are also opposite the printing template. For the printing process, the substrates are arranged individually or in groups, for example in a matrix, on the conveyor belt and then moved individually or together under the printing template. For the printing to proceed as expected, the substrates should be optimally aligned with the printing template. Therefore, the substrates are usually locked onto the conveyor belt and optimally aligned beforehand, for example, using optical markings on the substrates and the conveyor belt. To increase the cycle time of the printing device, the substrates are often placed on the conveyor belt away from the printing template and then moved by the conveyor belt into the printing device or into the printing position.The present invention is based on the objective of creating an improved printing system that ensures that the substrates are always optimally aligned with the printing template in the printing position.

[0005] The problem underlying the invention is solved by a printing system with the features of claim 1. This system has the advantage that any changes in the orientation or position of the conveyor belt that occur during operation of the printing system are taken into account in order to ensure optimal printing. For this purpose, the invention provides a control device for detecting the orientation and / or position of the conveyor belt relative to the printing template. By detecting the orientation and / or position, it is also possible to correct this orientation and / or position, for example, by repositioning the printing template and / or the conveyor belt. This ensures an optimal printing process at all times.

[0006] Preferably, the control device has at least one optical sensor, and in particular several sensors, for detecting the orientation of the conveyor belt relative to the printing template. The one or more optical sensors enable non-contact detection of the orientation, thereby reducing wear and ensuring particularly precise alignment and / or position detection.

[0007] Furthermore, it is preferably provided that the conveyor belt has several orientation openings, which are arranged or formed along at least one imaginary line in the direction of movement of the conveyor belt. During operation, the orientation openings thus move along a line of the conveyor belt in the direction of movement and can therefore be advantageously detected by the optical sensor for orientation and detection of the orientation and position of the conveyor belt relative to the print template. The line is thus aligned parallel to the longitudinal extent of the conveyor belt. The multiple orientation openings along the line of movement ensure that, regardless of the position of the conveyor belt, at least one orientation opening can be detected by the sensor at regular intervals.If the sensor is designed as a camera sensor, it can also simultaneously detect several orientation openings located in the sensor area of ​​the camera device in order to determine the orientation and position of the conveyor belt.

[0008] Preferably, the conveyor belt has at least two lines with orientation openings, as described above. These are then aligned parallel to each other due to their orientation in the direction of travel. Particularly preferably, the lines with orientation openings are arranged at the edges of the conveyor belt so that they are not obscured by the substrates being transported on the belt. Preferably, the orientation openings on the two lines are arranged parallel to each other or offset from each other.

[0009] Furthermore, it is preferably provided that each line with orientation openings is assigned one of the sensors on the rear side of the conveyor belt facing away from the support side. This ensures that the orientation openings of each line can be detected by a single sensor, thus guaranteeing a precise determination of the orientation and position of the conveyor belt.

[0010] Preferably, the printing template or a receptacle holding the printing template has at least one optical marker that can be detected by the respective sensor through one of the orientation openings, particularly if the orientation opening and the marker opening are in line with the sensor. To determine the relative position of the conveyor belt to the printing template, direct detection is thus provided, whereby the marker on the printing template or the receptacle can only be detected if the marker and the orientation opening are in line with the sensor. This ensures simple and rapid determination of the relative position. Preferably, the optical marker is a marker opening, in particular a bore or hole in a frame of the printing template, the printing stencil, or the printing screen itself, or in the receptacle holding the printing template.According to an alternative embodiment, the respective sensor is designed as a distance sensor or range sensor, which detects the maximum and desired distance when the orientation opening and the marking opening are in a line. Alternatively, the sensor is preferably designed as a camera sensor, so that image analysis can determine not only whether the marking opening and the orientation opening are aligned, but also whether they are exactly aligned or deviate from each other, even if, for example, the smaller marking opening is located entirely within the area of ​​the preferably larger orientation opening. This allows the camera device to directly detect any change in the position of the conveyor belt relative to the printing template.

[0011] According to a preferred embodiment of the invention, the control device comprises at least one evaluation unit configured to receive an image captured by the sensor designed as a camera sensor and to determine the relative position of the printing template to the conveyor belt by means of image evaluation. This thus provides an advantageous automated detection of the relative position of the conveyor belt to the printing template or vice versa.

[0012] Preferably, the transport device has at least one controllable actuator for aligning the conveyor belt. By controlling the actuator, a correction of the relative position can thus be carried out automatically.

[0013] Preferably, the control system or the pressure system includes a control unit designed or configured to control the actuator depending on the detected relative position, so that the relative position is corrected in particular.

[0014] The conveyor belt is preferably made of metal. This makes the conveyor belt relatively rigid and secure in terms of position and orientation, ensuring a secure hold for the substrates placed on it.

[0015] Preferably, the conveyor belt or metal belt has a plurality of vacuum openings, to which a vacuum device is assigned on the reverse side facing away from the support surface. A vacuum can be generated by means of the vacuum device, which acts on the underside or reverse side of the conveyor belt and draws the substrates located on the support side of the conveyor belt through the vacuum openings, thereby securely locking them to the conveyor belt. Preferably, the vacuum openings are spaced apart from the orientation openings in the conveyor belt. In particular, the vacuum openings are preferably located only in a region between the two lines of orientation openings. This also ensures that the respective sensor is not interfered with by the vacuum device.

[0016] Preferably, the conveyor belt or metal belt is closed or solid apart from the orientation openings and the vacuum openings, so that the vacuum device can work efficiently, and so that the sensors can only detect the orientation openings to avoid incorrect determinations of the relative position.

[0017] The invention will now be explained in more detail with reference to the drawing. The drawing shows:

[0018] Figures 1A and B show an advantageous printing system in a simplified representation, Figure 2 shows a detailed view of a conveyor belt of the printing system, and

[0019] Figure 3 shows a simplified side view of a control system of the printing system.

[0020] Figure 1 shows a simplified representation of an advantageous printing system 1 for printing on planar substrates, such as printed circuit boards or wafers. Figure 1A shows the printing system 1 in a simplified side view and Figure 1B shows the printing system in a simplified top view.

[0021] The printing system 1 comprises a frame or rack 2 on which a printing device 3 and a printing table 4 associated with the printing device 3 are arranged. The printing device 3 is designed as a doctor blade assembly. The printing table is formed by a conveyor belt 5 of a transport device 6. The conveyor belt 5 guides the substrates past the printing device 3. Thus, substrates can be placed at a first position A outside the rack 2 on a support side 7 of the conveyor belt 5, moved by the conveyor belt 5 according to arrow 8 to a printing position B below the printing device 3, printed there by the printing device 3, and then moved by the conveyor belt 5 to a removal position C outside the rack 2 or housing. The placement of the substrates at position A and the removal of the substrates from position C are preferably carried out manually or automatically.

[0022] Figure 2 shows a simplified top view detail of the conveyor belt 5 of the transport device 6, looking towards the support side 7. The conveyor belt 5 is designed as a metal belt, which is essentially closed and designed as an endless belt. Along its side edges, the conveyor belt 5 has several orientation openings 10, which are distributed along an imaginary line 11 (shown with dashed lines in Figure 2) in the direction of movement of the conveyor belt 5. In particular, the orientation openings 10 are evenly distributed along the edge in the direction of movement along line 11. According to the present embodiment, the orientation openings 10 are arranged parallel to each other at the two edge regions or edges of the conveyor belt 5. According to an alternative initial example, the orientation openings 10 are offset from each other at the edge regions.Between the two edge areas or lines 11, the conveyor belt 5 has a large number of vacuum openings 25, which are evenly distributed over the conveyor belt 5, but do not extend into the edge area with the orientation openings 10.

[0023] As shown in Figure 1A, a vacuum device 13 is assigned to the rear side 12 of the conveyor belt 5, which faces away from the support side 7. This vacuum device is designed to generate a vacuum on the rear side 12 that extends substantially along the length of the conveyor belt in the direction of movement indicated by arrow 8, i.e., at least from the support point A to at least the printing position B and optionally also to the removal point C. During operation, the vacuum device 13 generates a negative pressure on the rear side 12 of the conveyor belt 5. This pressure acts through the vacuum openings 25 on the substrates S placed on the support side, thereby drawing them against the support side 7 and securely locking them on the conveyor belt 5 for transport and at least for the printing process.

[0024] When the substrates S are placed on the conveyor belt 5, they are arranged in a way that is particularly optimal for the printing template, as shown by way of example in Figures 1B and 2, whereby several substrates S are preferably arranged in a matrix-like manner, so that a group of substrates S is fed to the printing device 3, printed and then removed. According to an alternative embodiment, the substrates S are placed individually, fed individually to the printing device 3 and printed individually.

[0025] During placement, the alignment of the substrates S is supported, in particular by a camera device 14, so that the substrates S are optimally aligned with respect to the printing device 3 during the printing process, especially with respect to a printing template 15 of the printing device 3, which is designed, for example, as a printing screen or printing stencil. The alignment of the substrates on the support point A is achieved, in particular, by means of optical markings on the conveyor belt. Such fudicials or registration marks are already known from the prior art. Optionally, the orientation openings 10 are used alternatively or additionally for aligning the substrates S on the conveyor belt 5.

[0026] The transport device 6 is further assigned a control system 16, by means of which the orientation of the transport belt 5 relative to the printing device 3, in particular to the printing template 15, can be detected. The control system 16 comprises several optical sensors 17, which are assigned to the rear side 12 of the transport belt 5, as shown, for example, in Figures 1A or 1B. The sensors 17 are designed, in particular, as camera sensors and are located in the area of ​​lines 11 below the transport belt 5 on the rear side 12 facing away from the printing device 3.

[0027] Figure 3 shows an enlarged detail view of a sensor 17 of the control system 16 below the conveyor belt 5. Because the sensor 17 is located in the area of ​​line 11, the orientation openings 10 are guided over the sensor 17 during normal operation, so that the sensor detects the orientation openings 10 by image evaluation. According to this initial example, the orientation openings 10 have a first diameter Dl.

[0028] The control system 16, which also includes orientation openings 10, furthermore has an optical marking 18, in the form of a marking opening 19 in the printing template 15 or in a frame or receptacle that secures the printing template 15. The marking openings 19 have a second diameter D2, which is smaller than the first diameter D1.

[0029] When the conveyor belt 5 is optimally aligned with the printing template 15, the orientation aperture 10 and the marking aperture 19 are precisely aligned, so that their centers lie in a line with the sensor 17. By detecting the orientation apertures 10 and the marking apertures 19, the alignment and position of the conveyor belt 5 relative to the printing template 15 can thus be advantageously monitored.

[0030] If the position or orientation of the conveyor belt 5 deviates from the optimal position or orientation due to wear or, for example, temperature-related dimensional changes, this is detected by the sensors 17. The control system 16 includes, in particular, a control unit 22, which has at least one evaluation unit 9. The evaluation unit 9 is connected to the sensors 17 to detect the orientation of the conveyor belt 5 relative to the print template 15. This is preferably done by means of image analysis, optionally with artificial intelligence and / or a neural network. If the centers of the marking aperture 19 and the orientation aperture 10 deviate from each other, it is determined that the orientation of the conveyor belt 5 relative to the print template has changed.

[0031] Preferably, the transport device 6 is assigned at least one actuator 20, which is designed or configured to influence the position and / or orientation of the conveyor belt 5 when activated. For this purpose, the actuator 20 acts, for example, on one of the transport rollers 21 through which the conveyor belt 5 is guided and driven. Optionally, several actuators 20 are provided, as shown in Figure 1B.

[0032] If the evaluation unit 9 detects that the conveyor belt 5 is no longer optimally aligned with the print template 15, the control unit 18 activates the actuators, or at least one of the actuators 20, to correct the alignment of the conveyor belt 5. This ensures consistently optimal printing results from the printing system 1.

Claims

REQUIREMENTS 1. Printing system (1) for printing, in particular, planar substrates (S), comprising a printing device (3), in particular a squeegee device, which has a printing template (15), which is in particular interchangeable, and a transport device (6) for feeding and removing substrates (S) to be printed to or from a printing position below the printing template (15), wherein the transport device (6) has a transport belt (5) which has a support side (7) for placing the substrates (S), characterized by a control device (16) for detecting an orientation and / or position of the transport belt (5) relative to the printing template (15).

2. Printing system according to claim 1, characterized in that the control device (16) has at least one optical sensor (17), in particular several sensors (17), for detecting the orientation of the transport belt (5) to the printing template (15).

3. Printing system according to one of the preceding claims, characterized in that the conveyor belt (5) has several orientation openings (10) which are arranged along at least one imaginary line (11) in the direction of movement of the conveyor belt (5).

4. Printing system according to one of the preceding claims, characterized in that the conveyor belt (5) has at least two imaginary lines (11) with orientation openings (10).

5. Printing system according to one of the preceding claims, characterized in that each line (11) with orientation openings (10) is assigned at least one of the sensors (17) on a rear side (12) of the conveyor belt (5) facing away from the support side (7).

6. Printing system according to one of the preceding claims, characterized in that the printing template (15) or a receptacle holding the printing template (15) has at least one optical marking (18), in particular a marking opening (19), which can be detected by the respective sensor (17) through one of the orientation openings (10).

7. Printing system according to one of the preceding claims, characterized in that the control device (16) has at least one evaluation device (9) which is configured to receive an image captured by the sensor (17) designed as a camera sensor and to process it by Image analysis to determine a relative position of the printing template (15) to the conveyor belt (5).

8. Printing system according to one of the preceding claims, characterized in that the transport system (6) has at least one controllable actuator (20) for aligning the transport belt (5).

9. Printing system according to one of the preceding claims, characterized in that the control system (16) has a control unit (22) which is configured to control the actuator (20) depending on the detected relative position.

10. Printing system according to one of the preceding claims, characterized in that the conveyor belt (5) is a metal belt.

11. Printing system according to one of the preceding claims, characterized in that the conveyor belt (5) has a plurality of vacuum openings (25) to which a vacuum device (13) is assigned on the rear side facing away from the support surface (7).

12. Printing system according to one of the preceding claims, characterized in that the conveyor belt (5) apart from the orientation openings (10) and the vacuum openings (25) is fully formed.

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