Abstract:
The embodiment of the present invention provides a method for a 3-D projection printing system and a system thereof, more particularly to a system adopts both ways of look-up table and interpolation method to calibrate. The embodiment of the present invention provides a portable calibration fixture system and a flexible 3-D projection printing system in order to improve calibration precision, facilitate calibration and printing operations, increase printing effect and save cost.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
       [0001]    The present invention generally relates to a method for a 3-D projection printing system and a system thereof, more particularly to a system adopts both the ways of look-up table and interpolation method to calibrate. 
       2. Description of the Prior Art 
       [0002]    In case the lens of the projector is malfunctioned or deformed by some reasons as hot environment, falling down, etc., and/or the whole system happens tolerances while in assembly, the precisions for the system may not exist. Such system is applied to the field of 3-D printing very often, and the printing quality cannot be assured if aforesaid conditions do occur. Hence, an advanced 3-D projection system with an advanced calibration method are deemed to be a developed issue to the people skilled in the art. 
       SUMMARY OF THE INVENTION 
       [0003]    One embodiment of the method for a 3-D projection printing system comprises the steps of: the 3-D projection printing system capturing a light-uniform device with a projected single second sample pattern thereon to obtain a second practical pattern, the second practical pattern being calibrated by a second camera look-up table to gain a calibrated pattern, a comparison of the calibrated pattern and the second sample pattern being a first projection look-up table which is transformed to a second projection look-up table with a projection resolution as a resulted projection look-up table, and the resulted projection look-up table being stored in the 3-D projection printing system; and the 3-D projection printing system using the resulted projection look-up table to calibrate a plurality of sliced printing files, and then the plurality of calibrated sliced printing files being used to engaged in a projection printing work. 
         [0004]    An embodiment of the present invention provides a method for a 3-D projection printing system and a system thereof, more particularly to a system adopts both ways of look-up table and interpolation method to calibrate. The embodiment of the present invention provide a portable calibration fixture system and a flexible 3-D projection printing system in order to improve calibration precision, facilitate calibration and printing operations, increase printing effect and save cost. 
         [0005]    Other and further features, advantages, and benefits of the invention will become apparent in the following description taken in conjunction with the following drawings. It is to be understood that the foregoing general description and following detailed description are exemplary and explanatory but are not to be restrictive of the invention. The accompanying drawings are incorporated in and constitute a part of this application and, together with the description, serve to explain the principles of the invention in general terms. Like numerals refer to like parts throughout the disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The objects, spirits, and advantages of the preferred embodiments of the present invention will be readily understood by the accompanying drawings and detailed descriptions, wherein: 
           [0007]      FIGS. 1A and 1B  illustrate a flow chart of a first preferred embodiment of the present invention; 
           [0008]      FIGS. 2-1 ˜ 4  illustrate a plurality of practical views of calibration fixture steps of the embodiment of the present invention; 
           [0009]      FIGS. 3-1 ˜ 5  illustrate a plurality of practical views of calibration projection steps of the embodiment of the present invention; 
           [0010]      FIG. 4  illustrates a schematic system block of the first preferred embodiment of the present invention; 
           [0011]      FIGS. 5A and 5B  illustrate a flow chart of a second preferred embodiment of the present invention; 
           [0012]      FIG. 6  illustrates a schematic system block of the second preferred embodiment of the present invention; and 
           [0013]      FIG. 7  illustrates a schematic view of a calibration projection system. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    Following preferred embodiments and figures will be described in detail so as to achieve aforesaid objects. 
         [0015]    According to  FIG. 7 , which illustrates a schematic view of a calibration projection system. The system includes a projector  51 , a diffuser  53 , a reflection mirror  55 , a camera  56 , and a computer  57 . The projector  51  projects a projected image  54  onto the diffuser  53 . The projected image  54  goes through the diffuser  53 , and then to the reflection mirror  55 . The reflection mirror  55  reflects the projected image  54  to the camera  56 . The camera  56  captures the reflected projected image  54 . Continuously, the captured image in the camera  56  is digitized and sent to the computer  57  via WIFI, USB, Bluetooth, cable, or the other wireless/wired methods. 
         [0016]    Please refer to  FIGS. 1A ˜ 1 B,  FIGS. 2-1 ˜ 4 ,  FIGS. 3-1 ˜ 5 , and  FIG. 4 , which illustrate a flow chart, plural practical views of calibration fixture steps, plural practical views of calibration projection steps, and a schematic system block of the first preferred embodiment of the present invention. As shown in  FIGS. 1A and 1B , the method includes the steps of: 
         [0000]    (S 1 ) providing a single first sample pattern  23  to a calibration fixture system  2 ;
 
(S 2 ) a distortion correction calculation unit  121  of a calculation control system  12 , which can be a computer for the preferred embodiment, of a 3-D projection printing system  1  using a camera  22  of the calibration fixture system  2  to capture the single first sample pattern  23 , as shown in  FIG. 2-1 ;
 
(S 3 ) obtaining a first practical pattern, as shown in  FIG. 2-2 ;
 
(S 4 ) the distortion correction calculation unit  121  determining a plurality of displacement amounts of the first practical pattern and the single first sample pattern  23  to gain a first camera look-up table, as shown in  FIG. 2-3 ;
 
(S 5 ) the distortion correction calculation unit  121  using an interpolation method to transform the first camera look-up table into a second camera look-up table with a camera resolution, as shown in  FIG. 2-4 , wherein the view in  FIG. 2-4  is larger than the view in  FIG. 2-3 , since the view in  FIG. 2-4  is with a higher resolution;
 
(S 6 ) the distortion correction calculation unit  121  storing the second camera look-up table;
 
(S 7 ) removing the single first sample pattern  23  from the calibration fixture system  2 ;
 
(S 8 ) providing a light-uniform device, which is a diffuser  21  for the preferred embodiment, to the calibration fixture system  2 ;
 
(S 9 ) the distortion correction calculation unit  121  using the projection system  1111  of the printing control system  111  to project a single second sample pattern  24  to the diffuser  21 , as shown in  FIG. 3-1 ;
 
(S 10 ) the distortion correction calculation unit  121  using the camera  22  to capture the single second sample pattern  24 ;
 
(S 11 ) the distortion correction calculation unit  121  using the second camera look-up table to calibrate a second practical pattern obtained by that of the camera  22  capturing the single second sample pattern  24 , as shown in  FIG. 3-2 ;
 
(S 12 ) obtaining a calibrated pattern, as shown in  FIG. 3-3 ;
 
(S 13 ) the distortion correction calculation unit  121  determining a plurality of displacement amounts of the calibrated pattern and the single second sample pattern  24  to gain a first projection look-up table, as shown in  FIG. 3-4 ;
 
(S 14 ) the distortion correction calculation unit  121  using the interpolation method to transform the first projection look-up table into a second projection look-up table  1121  with a projection resolution, as shown in  FIG. 3-5 , wherein the view in  FIG. 3-5  is larger than the view in  FIG. 3-4 , since the view in  FIG. 3-5  is with a higher resolution;
 
(S 15 ) the distortion correction calculation unit  121  storing the second projection look-up table  1121  into a storing unit  112  of a 3-D printing system  11  of the 3-D projection printing system  1 ;
 
(S 16 ) the distortion correction calculation unit  121  copying the second projection look-up table  1121  to a calculation control system  12  for becoming a third projection look-up table  122  as a resulted projection look-up table;
 
(S 17 ) the distortion correction calculation unit  121  using the third projection look-up table  122  to calibrate a plurality of sliced printing files  13 ;
 
(S 18 ) the distortion correction calculation unit  121  transmitting the plurality of calibrated sliced printing files  13  to a printing control system  111  of the 3-D printing system  11  of the 3-D projection printing system  1 ; and
 
(S 19 ) a projection system  1111  of the printing control system  111  engaging in a projection printing work.
 
         [0017]    Again, please refer to  FIG. 4 , the calibration fixture system  2  includes the single first sample pattern  23 , the projected single second sample pattern  24 , the light-uniform device as the diffuser  21 , wherein the camera  22  is used to capture the single first sample pattern  23  and the diffuser  21  with the projected single second sample pattern  24  thereon, and the reflection mirror  25  is used to reflect images of the camera  22  capturing the single first sample pattern  23  and the diffuser  21  with the projected single second sample pattern  24  thereon; and the 3-D projection printing system  1  has the 3-D printing system  11  and the calculation control system  12 , wherein the 3-D printing system  11  has the printing control system  111  with the projection system  1111  and the storing unit  112  with the second projection look-up table  1121 , and a computer (no shown in the  FIG. 4 ) engages that of using the camera  22  to capture the single first sample pattern  23  in order to obtain the first practical pattern, determining the plurality of displacement amounts of the first practical pattern and the single first sample pattern  23  to gain the first camera look-up table, using the interpolation method to transform the first camera look-up table into the second camera look-up table with the camera resolution, storing the second camera look-up table, using the projection system  1111  of the printing control system  111  to project the single second sample pattern  24  to the diffuser  21 , using the camera  22  to capture the single second sample pattern  24 , using the second camera look-up table to calibrate the second practical pattern obtained by that of the camera  22  capturing the single second sample pattern  24  so as to obtain the calibrated pattern, determining the plurality of displacement amounts of the calibrated pattern and the single second sample pattern  24  to gain the first projection look-up table, using the interpolation method to transform the first projection look-up table into the second projection look-up table  112  with the projection resolution, storing the second projection look-up table  1121  into the storing unit  112  of the 3-D printing system  11  of the 3-D projection printing system  11 , copying the second projection look-up table  1121  to the calculation control system  12  for becoming the third projection look-up table  122  as the resulted projection look-up table, using the resulted projection look-up table to calibrate the plurality of sliced printing files  13 , and transmitting the plurality of calibrated sliced printing files  13  to the printing control system  111 , and the projection system  1111  engaging in a projection printing work. 
         [0018]    Please refer to  FIGS. 5A ˜ 5 B,  FIGS. 2-1 ˜ 4 ,  FIGS. 3-1 ˜ 5 , and  FIG. 6 , which illustrate a flow chart of a second preferred embodiment, plural practical views of calibration fixture steps, plural practical views of calibration projection steps, and a schematic system block of the second preferred embodiment of the present invention. As shown in  FIGS. 5A and 5B , the method includes the steps of: 
         [0000]    (S 1 ′)˜(S 15 ′) is similar substantially as (S 1 )˜(S 15 ), so it is not described repeatedly here.
 
(S 16 ′) the distortion correction calculation unit  1131 ′ using the second projection look-up table  1121 ′ as a resulted projection look-up table to calibrate a plurality of sliced printing files  13 ′;
 
(S 17 ′) the distortion correction calculation unit  1131 ′ transmitting the plurality of calibrated sliced printing files  13 ′ to a printing control system  111 ′ of the 3-D printing system  11 ′ of the 3-D projection printing system  1 ′; and
 
(S 18 ′) a projection system  1111 ′ of the print control system  111  engaging in a projection printing work.
 
         [0019]    Again, please refer to  FIG. 6 , the calibration fixture system  2 ′ is similar substantially as the calibration fixture system  2 , so it is not described repeatedly here. 
         [0020]    The 3-D projection printing system  1 ′ includes the 3-D printing system  11 ′ which has the printing control system  111 ′ with the projection system  1111 ′, the storing unit  112 ′ and the calculation control system  113 ′ with the distortion correction calculation unit  1131 ′, wherein the a computer (not shown in the  FIG. 6 ) engages that of using the camera  22 ′ to capture the single first sample pattern  23 ′ in order to obtain the first practical pattern, determining a plurality of displacement amounts of the first practical pattern and the first sample pattern  23 ′ to gain the first camera look-up table, using an interpolation method to transform the first camera look-up table into the second camera look-up table with the camera resolution, storing the second camera look-up table, using the projection system  1111 ′ of the printing control system  111 ′ to project the single second sample pattern  24 ′ to the light-uniform device  21 ′, using the camera  22 ′ to capture the second sample pattern  24 ′, using the second camera look-up table to calibrate the second practical pattern obtained by that of the camera  22 ′ capturing the second sample pattern  24 ′ so as to obtain the calibrated pattern, determining a plurality of displacement amounts of the calibrated pattern and the second sample pattern  24 ′ to gain the first projection look-up table, using the interpolation method to transform the first projection look-up table into the second projection look-up table  1121 ′ with the projection resolution, storing the second projection look-up table  1121 ′ into the storing unit  112 ′ of the 3-D printing system  11 ′ of the 3-D projection printing system, using the second projection look-up table  1121 ′ as a resulted projection look-up table to calibrate the plurality of sliced printing files  13 ′, and transmitting the plurality of calibrated sliced printing files  13 ′ to a projection system  1111 ′ of a printing control system  111 ′ of a 3D printing system  11 ′ of the 3-D projection printing system  1 , and the projection system  1111 ′ engaging in a projection printing work. 
         [0021]    As it can be seen, the reflection mirror  25  for the first preferred embodiment and the reflection mirror  25 ′ for the second preferred embodiment can be neglected, hence the whole calibration fixture system may be decreased and lightened in volume and weight, since the calibration fixture system is portable. The camera  22  and  22 ′ for the two preferred embodiments must be with the function of higher resolutions, and can also be replaced by scanner or related image-capturing device. 
         [0022]    With reference to  FIG. 4  and  FIG. 6 , two communication interface  3  and  3 ′ for the first and second preferred embodiments play the roles to be communication media for the 3-D projection printing system  1  and the calculation control system  12  of the first preferred embodiment and the 3-D projection printing system  1 ′ and the calculation control system  113 ′ of the second preferred embodiment by way of cable, WIFI, USB, Blue Tooth, etc., or the other wireless/wired methods 
         [0023]    According to  FIG. 4 , the calculation control system  12  not designed in the 3-D printing system  11  is to lower cost and raise printing speed, since the calculation control system  12  could be in a cloud system. Correspondingly,  FIG. 6  represents that the calculation control system  113 ′ in the 3-D printing system  11 ′ is to increase convenience of printing. 
         [0024]    Each of the first sample patterns  23  and  23 ′ and the second sample patterns  24  and  24 ′ is a single and plane pattern, that is to say, the complex procedures of calibration is simplified, and the problem for depth of field may not be occurred, since only one single pattern is vertically faced to the camera. Further, the projected image/pattern is calibrated by means of the look-up table and the interpolation method, therefore time for calculation is saved and image jags phenomena may not happen. Practically, the 3-D printing system  11 / 11 ′ could be a 3-D printer; the printing control system  111 / 111 ′ could be a projector, a laser control system, a CPU, an FPGA, etc.; the projection system  1111 ′ could be a projector, etc.; the storing unit  112 / 112 ′ could be an SD card, an SDRAM, a flash memory, etc.; the calculation control system  12 / 113 ′ could be a computer, a station, a CPU, a software, a firmware, or a network system, etc.; the distortion correction calculation unit  121 / 1131 ′ could be hardware as FPGA (Field-Programmable Gate Array) accelerator, GPU (Graphic Processor Unit), etc., or software/firmware as C-code program, etc.; the calibration fixture system  2 / 2 ′ could be a jig; the light-uniform device  21 / 21 ′ could be a diffuser. In addition, the calibration fixture system  2 / 2 ′ as a jig could be portable. 
         [0025]    There are two results to prove what the steps (S 1 ) to (S 6 ), the steps (S 1 ′) to (S 6 ′), the steps (S 8 ) to (S 14 ), and the steps (S 8 ′) to (S 14 ′) of the embodiments have done is better. That is, the RMS (Root Mean Square) results of before and after going through the steps (S 1 ) to (S 6 ) or the steps (S 1 ′) to (S 6 ′) are 80.3 and 2.2; comparatively, the RMS (Root Mean Square) results of before and after going through the steps (S 8 ) to (S 14 ) or the steps (S 8 ′) to (S 14 ′) are 31.5 and 2.0. 
         [0026]    Although the invention has been disclosed and illustrated with reference to particular embodiments, the principles involved are susceptible for use in numerous other embodiments that will be apparent to persons skilled in the art. This invention is, therefore, to be limited only as indicated by the scope of the appended claims