Patent Publication Number: US-2019168250-A1

Title: Thin film coating system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to CHINESE Application Serial Number 201721677804.0, filed Dec. 6, 2017, which is herein incorporated by reference. 
     BACKGROUND 
     Field of Invention 
     The present invention relates to a thin film coating system, and especially relates to a thin film coating system to which a flexible display is applied. 
     Description of Related Art 
     In general, flexible electronic devices are manufactured by forming various elements on a flexible substrate or a conformal substrate of a plastic sheet and/or metal sheet. Materials used in the flexible electronic device include semiconductor materials such as amorphous silicon, low temperature polycrystalline silicon, and/or organic semiconductor material. In addition, materials used in printed electronics include thin-film silicon, inorganic or organic semiconductor to manufacture thin film transistors. The printed electronics may include roll to roll (R2R), a process that overcomes some of disadvantageous features found in silicon wafers, such as their non-soft nature, brittleness, or significantly large thickness. 
     SUMMARY 
     The present disclosure provides a thin film coating system. The thin film coating system includes at least one first supporting roller, a coating device, and at least one drying device. The first supporting roller is configured to rotate based on a rotating central axis. The coating device has an opening. The opening of the coating device faces toward the first supporting roller. The coating device is configured to coat a flowable material toward the first supporting roller along a first direction through the opening. The drying device is located at a side of the rotating central axis adjacent to the coating device in the first direction and is configured to dry the flowable material. 
     In some embodiments of the present disclosure, the opening has a first width, and the drying device has a second width in an extending direction of the rotating central axis. The first width is greater than the second width. 
     In some embodiments of the present disclosure, the thin film coating system further includes at least one second supporting roller. The second supporting roller is located at a side of the rotating central axis away from the drying device in the first direction, and is configured to support a flexible substrate where the flowable material is coated thereon. 
     In some embodiments of the present disclosure, the flowable material is metal oxide. 
     In some embodiments of the present disclosure, the drying device includes an infrared drying device. 
     In some embodiments of the present disclosure, the opening of the coating device has a projection. The projection is projected on the first supporting roller along the first direction. The infrared drying device and the projection of the opening of the coating device are spaced apart by a distance in a range from about 1 mm to about 100 mm. 
     In some embodiments of the present disclosure, the drying device includes an exhaust device. The exhaust device of the drying device has at least one inlet and at least one outlet. The opening of the coating device has a first projection projected on the first supporting roller along the first direction. The exhaust device faces toward the first supporting roller along a second direction and has a second projection. The second projection is projected on the first supporting roller along the second direction. The second projection of the exhaust device covers the first projection of the opening of the coating device. The second direction intersects the first direction. 
     In some embodiments of the present disclosure, a number of the at least one outlets are plural. The outlets of the exhaust device are equidistantly arranged on the exhaust device along an extending direction of the rotating central axis. 
     In some embodiments of the present disclosure, the exhaust device and the first projection are spaced apart by a distance in a range from about 10 mm to about 50 mm. 
     In some embodiments of the present disclosure, the second direction is substantially perpendicular to the first direction. 
     In the aforementioned configurations, the flowable material can be uniformly formed on the flexible substrate in the thickness direction of the flexible substrate. Furthermore, since the thin film coating system includes a drying device, there is no need to rest the flowable material until the fluidity of the flowable material disappears for subsequent processes. However, the drying effect can be achieved immediately by the drying device at the time when the flowable material is coated on the flexible substrate. As such, the metal oxide solution may be used in a roll to roll (R2R) process, which may be also referred to as a continuous process. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a thin film coating system and a flexible display in accordance with some embodiments of the present disclosure; 
         FIG. 2  is a cross-sectional view of a thin film coating system and a flexible display in accordance with some embodiments of the present disclosure; 
         FIG. 3  is a perspective view of a thin film coating system and a flexible display in accordance with some other embodiments of the present disclosure; and 
         FIG. 4  is a cross-sectional view of a thin film coating system and a flexible display in accordance with some other embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference is made to  FIG. 1  and  FIG. 2 .  FIG. 1  is perspective view of a thin film coating system  1  and a flexible display  3  in accordance with some embodiments of the present disclosure.  FIG. 2  is a cross-sectional view of the thin film coating system  1  and the flexible display  3  in accordance with some embodiments of the present disclosure. As shown in the figure, in the embodiment, the thin film coating system  1  includes at least one supporting roller (depicted as three, i.e., a first supporting roller  10   a , a second supporting roller  10   b , and a third supporting roller  10   c ), a coating device  12 , and at least one infrared drying device (IR heater)  16  (depicted as one). In the embodiment, the infrared drying device  16  is used as a drying device, but the present disclosure is not limited thereto. In some embodiments, any device that can be used to dry a flowable material  32  can be used in the present disclosure. 
     As shown in  FIG. 1  and  FIG. 2 , the first supporting roller  10   a  is configured to rotate based on a rotating central axis  100 . The second supporting roller  10   b  and the third supporting roller  10   c  are located at a side of the rotating central axis  100  away from the coating device  12  and the infrared drying device  16 . In the embodiment, a flexible substrate  30  is wound and attached to portions of outer surfaces of the first supporting roller  10   a , the second supporting roller  10   b , and the third supporting roller  10   c , and are configured to rotate with the rotation of the first supporting roller  10   a , thereby being wound around the portions of the outer surfaces of the first supporting roller  10   a , the second supporting roller  10   b , and the third supporting roller  10   c . Specifically, a portion of the flexible substrate  30  is wound and attached to a portion of an outer surface of the second supporting roller  10   b  adjacent to the third supporting roller  10   c . Then, another portion of the flexible substrate  30  is further wound and attached to a portion of an outer surface of the first supporting roller  10   a  away from the second supporting roller  10   b  and the third supporting roller  10   c . Then, the other portion of the flexible substrate  30  is further wound and attached to a portion of an outer surface of the third supporting roller  10   c  away from the second supporting roller  10   b.    
     In the embodiment, the flexible substrate  30  is a thin film. In some embodiments, the flexible substrate  30  is made by polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), copper (Cu), or any other suitable material. 
     In  FIG. 1  and  FIG. 2 , the coating device  12  has a body portion  120  and an opening  122  formed on the body portion  120 . The body portion  120  of the coating device  12  is housed the flowable material  32 . The opening  122  of the coating device  12  faces toward the first supporting roller  10   a  and has a first width W 1  (shown in  FIG. 1 ) in an extending direction of the rotating central axis  100 . The flowable material  32  is communicated with outside of the coating device  12  through the opening  122 . In the embodiment, the opening  122  of the coating device  12  has a first projection  124  (shown in  FIG. 2 ) projected on the first supporting roller  10   a  along a first direction D 1 . The coating device  12  is configured to coat the flowable material  32  toward the first supporting roller  10   a  along the first direction D 1  through the opening  122 . 
     As such, as shown in  FIG. 2 , the flexible substrate  30  is driven clockwise by the first supporting roller  10   a  and is wound around portions of out surfaces of the first supporting roller  10   a , the second supporting roller  10   b , and the third supporting roller  10   c  as the first supporting roller  10   a  rotates clockwise. Under the foregoing operation, the portion of the flexible substrate  30  that passes through the first projection  124  (see  FIG. 2 ) is coated with the flowable material  32 . 
     In the embodiment, the infrared drying device is located at a side of the rotating central axis  100  adjacent to the coating device  12  along the first direction D 1 . That is, the infrared drying device  16  is located at a side of the rotating central axis  100  away from the second supporting roller  10   b  and the third supporting roller  10   c . The infrared drying device  16  has a second width W 2  (shown in  FIG. 1 ) in the extending direction of the rotating central axis  100 , and is configured to dry the flowable material  32 . In the embodiment, the second width W 2  of the infrared drying device  16  is greater than the first width W 1  of the opening  122  of the coating device  12 , so as to ensure that the range of the infrared drying device  16  being able to cover the area where the flowable material  32  is coated. In the embodiment, the infrared drying device  16  and the first projection  124  (see  FIG. 2 ) of the opening  122  are spaced apart by a distance in a range from about 1 mm to about 100 mm, but the present disclosure is not limited thereto. 
     In the embodiment, the infrared drying device  16  utilizes radiation for thermal conduction and thus heats and dries the flowable material  32 . Furthermore, the infrared drying device  16  of the present embodiment is able to uniformly heat the flowable material  32  so that the degree of drying of the flowable material  32  in different positions may be uniform, thereby ensuring the stability of the flexible display  3 . For example, the infrared drying device  16  of the present embodiment may be a ceramic heater. The ceramic heater may include a ceramic tube and a resistive material combined with the ceramic tube. The symmetrical axis of the infrared drying device  16  is parallel to the rotating central axis  100 . After the ceramic heater is turned on, the ceramic tube of the of the ceramic heater absorbs visible and/or infrared light radiated by the resistive material, thereby enabling temperature of the ceramic tube to increase, so as to produce vibrations to form pure silicon-oxygen bond molecules to radiate far-infrared rays, and thereby heating and drying the flowable material  32 . 
     In practical application, the power used by the infrared drying device  16  may be in a range from about 50 Watts (W) to about 2000 Watts, and the voltage of the power thereof may be in a range from about 12 volts (V) to about 380 volts, but the present disclosure is not limited thereto. 
     The temperature of the infrared drying device  16  of the present embodiment may be controlled by changing the voltage of the power supply. As such, the infrared drying device  16  has good control over the heating temperature of the flowable material  32 . In addition, the infrared heating device  16  has good penetration on the flowable material  32 , so as to be able to heat the interior and exterior of the flowable material  32  simultaneously, and may heat the flowable material  32  locally to save energy. 
     In the embodiment, the flowable material  32  is made by metal oxide. In some embodiments, the flowable material  32  may be transparent oxide semiconductor. Since the metal oxide solution has low viscosity and good fluidity, the metal oxide solution can be uniformly formed on the flexible substrate  30  in the thickness direction of the flexible substrate  30 . Furthermore, since the thin film coating system  1  includes infrared drying device  16 , there is no need to rest the metal oxide solution until the fluidity of the metal oxide solution disappears for subsequent processes. However, the drying effect can be achieved immediately by the infrared drying device  16  at the time when the flowable material  32  is coated on the flexible substrate  30 . 
     That is, with the foregoing configuration, after the coated flowable material  32  is driven by the flexible substrate  30  to leave the range of the first projection  124  (see  FIG. 2 ), the flowable material  32  is substantially dried by the infrared drying device  16  and loses of fluidity thereof, so the flexible display  3  can be directly connected to a next process. As such, the metal oxide solution may be used in a roll to roll (R2R) process which may be also referred to as a continuous process. 
     Reference is made to  FIG. 3  and  FIG. 4 .  FIG. 3  is a perspective view of a thin film coating system  2  and the flexible display  3  in accordance with some other embodiments of the present disclosure.  FIG. 4  is a cross-sectional view of the thin film coating system  2  and the flexible display  3  in accordance with some other embodiments of the present disclosure. Structures shown in  FIG. 3  and  FIG. 4  includes at least one supporting roller (depicted as three, i.e., a first supporting roller  10   a , a second supporting roller  10   b , and a third supporting roller  10   c ), a coating device  12 , and at least one exhaust device  26  (depicted as one). The structure and function of the components and their relationships are substantially the same as the structure shown in  FIG. 1  and  FIG. 2 , and the related detailed descriptions may refer to the foregoing paragraphs, and are not described again herein. It is noted that, the difference between the present embodiment and the embodiment in  FIG. 1  and  FIG. 2  is in that the exhaust device  26  is used as the drying device instead of the infrared drying device  16  shown in  FIG. 1  and  FIG. 2 , but the present disclosure is not limited thereto. In some embodiments, any device that can be used to dry the flowable material  32  can be used in the present disclosure. 
     As shown in  FIG. 3  and  FIG. 4 , the exhaust device  26  has at least one inlet  260  (depicted as one) and least one outlet  262  (depicted as three). The exhaust device  26  is located at a side of the rotating central axis  100  adjacent to the coating device  12  along the first direction D 1 . The inlet  260  of the exhaust device  26  has a third width W 3  (shown in  FIG. 3 ) in the extending direction of the rotating central axis  100 , and is configured to dry the flowable material  32 . In the embodiment, the third width W 3  of the exhaust device  26  is greater than the first width W 1  of the opening  122  of the coating device  12  (see  FIG. 3 ), so as to ensure that the range of the exhaust device  26  being able to cover the area where the flowable material  32  is coated. 
     In the embodiment, the inlet  260  of the exhaust device  26  faces toward the first projection  124  of the opening  122 , and has a second projection  264  shown in  FIG. 4 ) projected on the first supporting roller  10   a  along a second direction D 2 . The second projection  264  of the exhaust device  26  covers the first projection  124  (shown in  FIG. 4 ) of the opening  122  on the first supporting roller  10   a . In some embodiments, the second direction D 2  intersects the first direction D 1 . In the embodiment, the second direction D 2  is substantially perpendicular to the first direction D 1 . 
     The outlets  262  of the exhaust device  26  are equidistantly arranged on the exhaust device  26  along an extending direction of the rotating central axis  100 , so as to stabilize the pumping speed of the exhaust device  26  in the extending direction of the rotation center axis  100 , so that the exhaust device  26  is able to uniformly dry the flowable material  32 . In the embodiment, the exhaust device  26  and the first projection  124  of the opening  122  are spaced apart by a distance in a range from about 10 mm to about 50 mm, but the present disclosure is not limited thereto. 
     In some embodiments, the infrared drying device  16  shown in  FIG. 1  and  FIG. 2  may be able to be further disposed at a side of the rotating central axis  100  adjacent to the coating device  12  along the first direction D 1  in the thin film coating system  2  to increase the drying rate of the flowable material  32 . In some embodiments, any device that can be used to dry a flowable material  32  may be able to use in the film coating system  2  at the same time. Similarly, in some embodiments, any device that can be used to dry a flowable material  32  may be able to use in the film coating system  1  shown in  FIG. 1  and  FIG. 2  at the same time. 
     According to the foregoing embodiments of the disclosure, it can be seen that, the flowable material can be uniformly formed on the flexible substrate in the thickness direction of the flexible substrate. Furthermore, since the thin film coating system includes drying device, there is no need to rest the flowable material until the fluidity of the flowable material disappears for subsequent processes. However, the drying effect can be achieved immediately by the drying device at the time when the flowable material is coated on the flexible substrate. As such, the metal oxide solution may be used in a roll to roll (R2R) process which may be also referred to as a continuous process.