WO2020095300A1

WO2020095300A1 - On line registration using compensation

Info

Publication number: WO2020095300A1
Application number: PCT/IL2019/051213
Authority: WO
Inventors: Ezra SCHVARTZMAN
Original assignee: Kornit Digital Ltd.
Priority date: 2018-11-08
Filing date: 2019-11-06
Publication date: 2020-05-14
Also published as: WO2020095300A9

Abstract

A textile printer comprises a controller, multiple print stations, and a conveyor to convey pallets between the print stations carrying textiles for printing. The pallets include visible locator marks at predetermined positions thereon. A camera at a predetermined location at each print station, images the pallets to determine the location of an arriving pallet. The locations are used to ensure that the pallet is correctly registered at each subsequent station relative to the pallet position at the first station.

Description

ON LINE REGISTRATION USING COMPENSATION

RELATED APPLICATION/S

This application claims the benefit of priority of U.S. Provisional Patent Application No. 62/757,181 filed on November 8, 2018, the contents of which are incorporated herein by reference in their entirety.

FIELD AND BACKGROUND OF THE INVENTION

The present invention, in some embodiments thereof, relates to on-line registration and, more particularly, but not exclusively, to an on-line registration system for textile printing that is closed loop.

Textile printers come in several types, and one of these types has different stations that carry out different parts of the printing process. Thus one station may print white, another may print black and color, and the like.

It will be appreciated that in order for such a station-based system to work, the item to be printed needs to be lined up correctly at the different stations. Otherwise pixels that are supposed to correspond with each other may miss, blurring or ruining the image being printed.

In existing station-based printing systems there are a number of current solutions. One of the solutions is to use a mechanical registration system in which the pallet carries two hollow sockets, and the sockets comes to rest at each station against cone-shaped locators. The system works in general but there is ripple over time, requiring regular recalibration which is difficult. The result is not accurate enough for the micron-sized pixels currently being used in ink-jet printing. The assumption is that the pallet is permanently fitted onto the conveyor.

Another solution is simply to rely on the accuracy of the conveyor mechanism. The pallet is fixed on the conveyor as a pallet train, and the conveyor uses a sufficiently accurate motor, for example a linear motor. However, again the mechanics of the system are not necessarily well enough defined to provide sufficient accuracy for the micron-sized pixels currently available. Furthermore the relationships may ripple with time and recalibrating is not easy. Furthermore, since the pallets are fixed in the train, it is difficult or impossible to load pallets offline and add them to vacant spaces on the conveyor, or to have alternative sets of pallets for different kinds of tasks.

In any event, neither of the above solutions are suitable where the pallets are designed to be removable so that the mechanical relationship between pallet and conveyor may vary. That is to say, the different pallets are placed at different positions on the conveyor. Furthermore, none of the above solutions address the ripple in the mechanical integrity of the parts over time, which is to say all of the existing solutions rely on the mechanics of the system staying stable at least between calibrations. Since calibrations are few and far between the mechanics have to be very stable, making them relatively expensive.

Semiconductor fabrication plants use marks inscribed on the semiconductor. However this is not possible for clothing since first of all one cannot inscribe on fabric as such and secondly, if a mark printed on the fabric were used it spoil or damage the fabric. If a sticker were placed on the garment, it may overcome the accuracy issues but it would not allow allover printing. Furthermore, for each print job one would need to independently determine a location that is not being printed on, thus increasing the level of manual involvement in the process.

SUMMARY OF THE INVENTION

The present embodiments may provide a self-calibrating registration system. At any station the actual position of a pallet is measured and then the motion system is used to carry the print-head to a corrected position to match with the actual position of the pallet.

Embodiments may measure relative positions at successive stations. The pallet position is measured at the first station and then mechanically moved to the second station where its position is measured. The absolute position measured is translated into a position relative to that at the first position, and at each station the pallet is moved to a position fixed relative to the previous position. Then a correction using a stored offset is carried out to place the print head at a correct location for the actual measured position of the pallet. Any deviation between expected and measured position is added to the offset and then used to correct the position of the next pallet, and thus ripple over time in accuracy is taken into account and compensated for.

Embodiments may use optical positioning. For example, a camera at a fixed position on the mechanism may measure the location of a target placed on the printing pallet when at one station. The pallet moves to the new station to a position calculated according to a previously measured offset. The new position is measured optically in the same way, and any deviation in the position is then added to the previously measured offset.

Thus a closed loop registration system deals with ripple in the mechanical integrity over time by providing continual recalibration.

According to an aspect of some embodiments of the present invention there is provided a method for corresponding registration at successive print stations of an object to be printed at the successive stations, the method comprising:

placing the object on a pallet, the pallet having a locator mark; placing the pallet at a first of the successive stations and measuring a position of the locator mark;

moving the pallet towards a corresponding position at a further one of the successive stations;

correcting the corresponding position using a preset offset;

measuring a current position of the optical mark at the further station following use of the preset offset; and

measuring any deviation between the corresponding position and the current position; and updating the preset offset to compensate for the deviation.

In an embodiment, the measuring of the locator mark comprises optical measuring.

In an embodiment, the locator mark is an optical mark and the optical measuring uses cameras at fixed locations.

In an embodiment, the measuring is carried out by taking continuous images until a respective locator mark converges on a stationary location.

In an embodiment, the measuring is triggered by the pallet being stationary or by an external trigger.

The method may comprise using two locator marks or two cameras to detect a rotation angle of the pallet, thereby to allow for the offset to compensate for rotation of the pallet.

In an embodiment, the locator mark comprises an angle indicator to allow for measurement of rotation.

In an embodiment, the locator mark is a visible mark on a predetermined corner of the pallet.

According to a second aspect of the present invention there is provided a pallet for carrying a printing job between printing stations, the pallet carrying a locator mark for optical registration of the pallet at each station.

In an embodiment, the locator mark comprises an angle indicator to allow for detection of rotation.

In an embodiment, the locator mark is located at a predetermined corner of the pallet.

According to a third aspect of the present invention there is provided a textile printer comprising:

a controller;

multiple print stations including a first station and at least one subsequent station;

a conveyor to convey pallets between the print stations, the pallets for carrying textiles for printing, the pallets including respective locator marks at predetermined positions thereon; and at least one camera at a predetermined location at each print station, the camera configured to image pallets arriving at the respective station to determine an actual location of an arriving pallet, the controller being configured to determine a relative location at the at least one subsequent station with the first station, thereby to register respective pallets at the at least one of the subsequent locations.

An embodiment may be configured to provide the respective station locations to the controller to update a position offset to compensate for position errors in the pallet location compared to an expected pallet location, the compensation involving moving the print head.

In an embodiment, the controller is configured to use the updated position offset to operate the conveyor when conveying a following pallet to the at least one respective subsequent station.

In an embodiment, at least one of the cameras is configured to take continuous images until a respective locator mark converges on a stationary location.

In an embodiment, at least one of the cameras is triggered to take an image by the respective pallet being stationary or by an external trigger.

In an embodiment, two locator marks are placed on at least one pallet to allow for detection of rotation by a respective pallet.

In an embodiment, at least one of the stations comprises two cameras to detect a rotation angle of the pallet.

In an embodiment, the locator mark comprises an angle indicator to allow for measurement of rotation by a respective pallet.

An embodiment may issue a warning if rotation is detected.

An embodiment may modify printing to compensate for detected rotation.

The locator marks may be placed on the opposite side of the pallet from the textile. Thus for example the mark may be on the underside of the pallet when the pallet travels through the printer, whereas the textile for printing is placed on the upper side of the pallet. Thus the textile does not obscure the locator mark, even if inaccurately placed.

Unless otherwise defined, all technical and/or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the invention, exemplary methods and/or materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting. Implementation of the method and/or system of embodiments of the invention can involve performing or completing selected tasks automatically, or semi-automatically. Moreover, according to actual instrumentation and equipment of embodiments of the method and/or system of the invention, several selected tasks could be implemented by hardware, by software or by firmware or by a combination thereof using an operating system.

For example, hardware for performing selected tasks, such as calculating offsets and directing motion of the conveyor, according to embodiments of the invention could be implemented as a chip or a circuit. As software, the selected tasks according to embodiments of the invention could be implemented as a plurality of software instructions being executed by a computer using any suitable operating system. In an exemplary embodiment of the invention, one or more tasks according to exemplary embodiments of a method and/or system as described herein are performed by a data processor, such as a computing platform for executing a plurality of instructions. Optionally, the data processor includes a volatile memory for storing instructions and/or data and/or a non-volatile storage, for example, a magnetic hard-disk and/or removable media, for storing instructions and/or data. Optionally, a network connection is provided as well. A display and/or a user input device such as a keyboard or mouse are optionally provided as well.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

Some embodiments of the invention are herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of embodiments of the invention. In this regard, the description taken with the drawings makes apparent to those skilled in the art how embodiments of the invention may be practiced.

In the drawings:

Fig. 1 is a simplified diagram showing a station-based printing device with optical registration according to a first embodiment of the present invention;

Fig. 2 is a simplified diagram showing the printing pallet of Fig. 1;

Fig. 3 is a simplified diagram showing an exemplary optical mark for use in the present embodiments;

Fig. 4 is a simplified diagram showing the underside of the pallet of Fig. 1 according to one embodiment of the present invention;

Fig. 5 is a simplified diagram showing the underside of the pallet of Fig. 1 according to a second embodiment of the present invention; Fig. 6 is a simplified flow chart showing operation of the printing device of Fig. 1; and

Fig. 7 is a vector diagram illustrating measurements made by the optical registration apparatus of the present embodiments.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

The pallet that carries the garment or other textile item to be printed is provided with an optical marker and the marker is detected by a camera at the first station to measure the actual position. The pallet then moves to a further station and the motion is corrected using an existing correction factor so as to give a fixed relative position. At the same time the actual position at the further station is measured optically and any deviation from the expected position is added to the existing correction factor to provide a new correction factor. The print head is moved to a location dictated by the actual position of the pallet.

The use of optical detection according to the present embodiments thus finds the pallet position at the first station, dealing with the fact that the pallet is not at a fixed position on the conveyor. Furthermore the motion and correction ensures that the pallet reaches the same relative position at each following station, thus providing registration. Thirdly, the optical detection at the further station and the adjustment of the correction factor ensures that the system calibration is constantly updated.

The marker may be placed on a part of the pallet that is not likely to be obscured by the textile placed thereon for printing and furthermore is not vulnerable to being clogged or obscured by waste ink. Typically, the textile is placed on the upper side of the pallet as it travels through the printer so the marker is placed on the underside.

Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not necessarily limited in its application to the details of construction and the arrangement of the components and/or methods set forth in the following description and/or illustrated in the drawings and/or the Examples. The invention is capable of other embodiments or of being practiced or carried out in various ways.

Referring now to the drawings, Fig. 1 illustrates a textile printer 10 having a controller 12 and multiple print stations 14 and 16, of which two are shown by way of example. A conveyor 18 conveys pallets 20 through the printer between the print stations 14 and 16, and the pallets carry textiles such as dress 22 for printing. The pallets including locator marks or targets, such as mark 24 shown in Fig 3, at specified positions on the pallet as shown in Figs. 4 and 5. In examples the marks 24 may be located on the underside of the pallet so that textiles to be printed do not inadvertently obscure the mark.

Cameras 26 and 28 are placed at a fixed and preselected location at each print station, typically at positions having a clear view of the undersides of the pallets. The camera images the pallets arriving at the first station to determine the initial pallet location against which relative positions are to be measured on further stations. At the particular station, the camera position is known and the camera looks for the mark 24 to make a measurement. The print head is moved into position as dictated by the measured location of the pallet.

The pallet is then moved to the further station by the conveyor using a motion which is corrected according to a previously stored position offset. The offset takes into account the position actually arrived at by the previous pallet to correct the conveyor, and the pallet is brought to the correct stopping point to allow for accurate printing in which the pixels printed now match up with pixels printed from the previous station. At the further stations the pallet position is measured optically, as before, after correction to the motion, and the actual position is determined, as will be described in greater detail below. At the second, and subsequent stations if any, the position of the mark in the image is compared to the expected position and any deviation is reported to controller 12. Any current deviation is added to the previously stored position offset to update the correction for the next pallet. Thus any error - the deviation - in the current location, is provided to the controller to update the position offset to compensate for position errors in the pallet location. Again, the print head is moved into position based on the actual position of the pallet. In some embodiments the update is applied to the current pallet and in others the update is not applied to the current pallet, but only to the following pallet.

In this way, the registration may be recalibrated for each pallet arrival, and thus gradual changes in the mechanics of the printer are catered for.

Camera operation at any given station may be either continuous or trigger based. That is to say the camera may take continuous images of the pallet, and when successive images converge on a single location, indicating that the pallet has stopped, a measurement of the location may be taken.

Alternatively, the cameras may be triggered using an external trigger. For example a trigger may be produced to indicate that the conveyor has stopped, or that a stepper motor has ceased to increment.

Reference is now made to Fig. 2 which shows the upper side of a pallet according to the present embodiments that includes a visual mark on the underside. The pallet travels on the conveyor 18 and carries garment 22 which is to be printed at multiple stations. In an example, station 14 may apply pre-processing material, such as wetting material, and station 16 may apply white ink. A further station - not shown - may apply color ink. A yet further station may apply post-processing treatments.

Reference is now made to Fig. 3 which illustrates a mark that may be placed on the pallet to allow the cameras to identify the position of the pallet. The mark comprises three concentric circles, an inner circle 30, an intermediate circle 32 and an outer circle 34, where each circle increases in thickness with radius. Within inner circle 30 is a cross 36, aligned with circle 30 so that the center of the cross is the center of circle 30. The lines of the cross are at 90 degrees to each other to give a clear orientation of the pallet, that is, to serve as an angle indicator. The lines of the cross continue as double lines in between the first 30 and second 32 circles, as double lines with increased thickness between the second 32 and third 34 circles, and finally with maximal thickness outside the third circle 34.

Referring now to Fig. 4 and the underside of the pallet 20 is shown in accordance with an exemplary embodiment of the present invention. As shown an optical marker as shown in Fig. 3 is located at one comer of the pallet. The cameras at each station see the pallet and are able to measure a deviation, as explained.

Referring now to Fig. 5 and a variation of the pallet of Fig. 4 is shown in which visual mark 24 is as located in Fig. 4 and a second mark 40 is located at the opposite comer. The second mark allows for more accurate detection of rotation by the pallet, even though this is not strictly necessary due to the angle indicators on the single mark.

As an alternative, one or more of the stations may have two cameras at different positions to detect a rotation angle of the pallet.

If rotation is detected then one option is to adjust the printing operation at the given station for the rotated angle. However this may not be feasible and another option is simply to set an alarm to alert an operator that rotation has occurred.

Reference is now made to Fig. 6, which is a simplified flow diagram illustrating operation according to one embodiment of the present invention. As explained the pallets carrying the objects being printed, typically textiles, have to register at corresponding locations at successive stations to a required degree of accuracy so that pixels printed at the different stations match up.

The method begins by providing a pallet with one or more locator marks - 60. An object to be printed, such as a garment, may then be placed on the pallet - 62- which is now drawn through the printer by the conveyor. The pallet arrives at a first station - 64, and the position is measured optically -66, for example using a camera at a fixed location on the station, and the locator mark on the pallet.

The pallet then moves to a further station on the printer - 68 - and comes to a stop at a location based on a fixed movement of the conveyor which is measured and the print head is moved in accordance with the actual position of the pallet, as corrected by the currently stored offset - 70. As the pallet stops, the actual position is measured again optically using the position of the locator mark. Any deviation between the current measured position and the expected position is added to the offset, so that the offset is updated for use in correcting the positioning of the next pallet.

As discussed above, the marker may be placed on a part of the pallet that is not likely to be obscured by the textile placed thereon for printing and furthermore is not vulnerable to being clogged or obscured by waste ink. Typically, the textile is placed on the upper side of the pallet as it travels through the printer so the marker is placed on the underside.

Now considered in greater detail, the station-based textile printer may use a pallet train to convey garments between a loading point and different stations say from a white printing station to a color printing station. The final position of the pallet in a printing station is provided in order for the system to be able to jet a color ink drop onto a white ink drop, that is to ensure that the pixels match up.

The optical registration system as discussed above may be set up as follows:

Optical targets, the visual indicators 24 as discussed above may be mounted on a corner of a pallet 20 on the bottom side as discussed above in respect of Fig. 3. Cameras such as cameras 26 and 28 are located on a print station, mounted rigidly on the chassis and facing upwards in the direction of a target 24. The system may typically support one or two cameras per station for any number of stations.

After the pallet is positioned in a print station, the camera may be triggered to measure the position of the target. Target position is defined by the center of the target, as shown below.

Reference is now made to Fig. 7, which is a simplified diagram showing the co-ordinates and measurements used for registration.

There are 3 different coordinate systems as defined by the optical setup:

1. Camera. The camera has a built-in coordinate system, X/Y 70.

2. Target. Printed data on target 24 defines a coordinate system. X'/Y' 72.

3. Motion. At each station, a print head carriage 29 is mounted on a motion system, and the motion is according to a third coordinate system X"/Y" 76. There are four assumptions as follows:

1. The target is mounted so that its position may be measured within a radius of 141mhi from the camera.

2. The target is mounted on the pallet, rotated up to 2° relative to the pallet orientation.

3. Optional - the pallet is not rotated relative to the print station, only translated. If this assumption is not valid then two cameras per station and two targets per pallet are needed.

4. Based on the first 2 assumptions above - the displacement of the pallet as measured by the camera may be passed to the motion system. With these two limitations the difference between the motion system and the target system may be 3mhi or less.

Thus, if the target is spotted within a radius of l4lmicrons on the camera coordinate system or the target is rotated less than 2 degrees relative to the print head coordinate system, then no rotation calibration is needed.

System rotation

In the example above, the target is rotated Q degrees relative to the camera. The angle Q is measured by the camera - using the cross extension lines built in to the target.

The target position in the camera's coordinate system 70 is:

X & Y.

The target position in the target coordinate system 72, that is equivalent to the motion system, is:

X"=Xcos Q+Ysin Q

Y' '=-Xsin Q+Ycos Q

Having q=2° C=100m U=100m, yields - C"=103.4m U"=96.4m.

This result, indicates a correction of no more than 3m to the motion system, and thus matching assumption four above.

Based on the above, registration may be carried out as follows:

1. Measure pallet position for the I^st time, on the first (white) station, refer to as R^wo.

2. Measure pallet position for the I^st time, on the second (color) station, referred to as R^co.

3. Refer to the reference relative position as ARo= R^wo-R^co-

4. Use the registration wizard to correct registration deviations.

5. Measure pallet position for the i^Lh time, on the white station, refer to as R ,.

6. Measure pallet position for the i^Lh time, on the color station, refer to as R ,.

7. Refer to the reference relative position as AR;= R^wi-R^ci.

8. Before starting to print - correct motion system according to AR= ARi-ARo. 9. Before any print - use steps 5 to 8.

The system in general may measure the position of a target at an overall accuracy of

2.5 mih.

As discussed above, the camera may support two operating modes:

1. Idle. On an external trigger, the camera may grab an image and start processing.

2. Continuous. The system may continually grab images, and start processing when the target image is stable, i.e. is sufficiently stationary to yield an overall accuracy of 2.5 m.

It is expected that during the life of a patent maturing from this application many relevant optical measurement technologies will be developed and the scopes of the corresponding terms are intended to include all such new technologies a priori.

The terms "comprises", "comprising", "includes", "including", “having” and their conjugates mean "including but not limited to".

As used herein, the singular form "a", "an" and "the" include plural references unless the context clearly dictates otherwise.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination or as suitable in any other described embodiment of the invention. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.

Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention. To the extent that section headings are used, they should not be construed as necessarily limiting.

In addition, any priority document(s) of this application is/are hereby incorporated herein by reference in its/their entirety.

Claims

WHAT IS CLAIMED IS:

1. A method for corresponding registration at successive print stations of an object to be printed at said successive stations, the method comprising:

placing said object on a pallet, the pallet having a locator mark;

placing said pallet at a first of said successive stations and measuring a position of said locator mark;

moving said pallet towards a corresponding position at a further one of said successive stations,

correcting said corresponding position using a preset offset;

measuring a current position of said optical mark at said further station following use of said preset offset; and

measuring any deviation between said corresponding position and said current position; and

updating said preset offset to compensate for said deviation.

2. The method of claim 1, wherein said measuring of said locator mark comprises optical measuring.

3. The method of claim 1 or claim 2, wherein said locator mark is an optical mark and said optical measuring uses cameras at fixed locations.

4. The method of any one of the preceding claims, wherein said measuring is carried out by taking continuous images until a respective locator mark converges on a stationary location.

5. The method of any one of claims 1 to 4, wherein said measuring is triggered by the pallet being stationary or by an external trigger.

6. The method of any one of the preceding claims, comprising using two locator marks or two cameras to detect a rotation angle of said pallet, thereby to allow for said offset to compensate for rotation of said pallet.

7. The method of any one of claims 1 to 5, wherein said locator mark comprises an angle indicator to allow for measurement of rotation.

8. The method of any one of the preceding claims, wherein the locator mark is a visible mark on a predetermined comer of said pallet.

9. A pallet for carrying a printing job between printing stations, the pallet carrying a locator mark for optical registration of said pallet at each station.

10. The pallet of claim 9, wherein said locator mark comprises an angle indicator to allow for detection of rotation.

11. The pallet of claim 9 or claim 10, wherein said locator mark is located at a predetermined corner of said pallet.

12. A textile printer comprising:

a controller;

a conveyor to convey pallets between the print stations, the pallets for carrying textiles for printing, the pallets including respective locator marks at predetermined positions thereon;

at least one camera at a predetermined location at each print station, the camera configured to image pallets arriving at said respective station to determine an actual location of an arriving pallet, the controller being configured to determine a relative location at said at least one subsequent station with said first station, thereby to register respective pallets at said at least one of said subsequent locations.

13. The textile printer of claim 12, configured to provide the respective station locations to said controller to update a position offset to compensate for position errors in said pallet location compared to an expected pallet location, said compensation involving moving said print head.

14. The textile printer of claim 13, wherein said controller is configured to use said updated position offset to operate said conveyor when conveying a following pallet to said at least one respective subsequent station.

15. The textile printer of any one of claims 12 to 14, wherein at least one of said cameras is configured to take continuous images until a respective locator mark converges on a stationary location.

16. The textile printer of any one of claims 12 to 15, wherein at least one of said cameras is triggered to take an image by the respective pallet being stationary or by an external trigger.

17. The textile printer of any one of claims 12 to 15, wherein two locator marks are placed on at least one pallet to allow for detection of rotation by a respective pallet.

18. The textile printer of any one of claims 12 to 17, wherein at least one of said stations comprises two cameras to detect a rotation angle of said pallet.

19. The textile printer of any one of claims 12 to 18, wherein said locator mark comprises an angle indicator to allow for measurement of rotation by a respective pallet.

20. The textile printer of any one of claims 12 to 19, configured to issue a warning if rotation is detected.

21. The textile printer of any one of claims 16 to 20, configured to modify printing to compensate for detected rotation.

22. The textile printer of any one of claims 12 to 21, wherein the locator mark is a visible mark on a predetermined comer of said pallet.

23. The textile printer of any one of claims 12 to 22, wherein the locator mark is placed on an opposite side of said pallet from a surface used for placement of said textile for printing, and wherein said cameras are located to have a view of said locator mark.

24. The textile printer of claim 23, wherein the locator mark is placed on an underside of said pallet.