Patent Publication Number: US-9890998-B2

Title: Substrate heating apparatus

Description:
FIELD 
     The present disclosure relates to a substrate heating apparatus. 
     BACKGROUND 
     A manufacturing procedure of a display panel comprises mainly three processing stages: array processing, cell processing and module processing, in which, the array processing is primarily responsible for providing an array substrate for the cell processing. 
     In particular, the array processing comprises a continuous cycle of four processes performed on a glass substrate, i.e., film forming, masking, exposing and etching, and ultimately a desired pattern of thin-film-transistor (TFT) array is fabricated on the glass substrate, thereby forming an array substrate. In the masking process, the glass substrate after being coated with a photosensitive material needs to be heated, for allowing the photosensitive material coated on the glass substrate to be partially-cured, so as to ensure the quality of exposure with ultraviolet light on the photosensitive material during subsequent exposing process.  FIG. 1  shows a conventional heating apparatus for heating a glass substrate. The heating apparatus comprises: a heating chamber  1 ′ for receiving a glass substrate, and a heating unit  3 ′ provided at the bottom of the heating chamber  1 ′; and a plurality of supporting pins  4 ′ on the heating unit  3 ′ for supporting the glass substrate.  FIG. 2  is an enlarged view of a supporting pin  4 ′. The glass substrate faces the heating unit  3 ′. Here, it should be noted that in order to see clearly the supporting pins  4 ′ inside the heating chamber  1 ′, the top (i.e., the cover  2 ′) of the heating chamber shown in  FIG. 1  is in an opened state. In addition, the cover  2 ′ can be opened to facilitate maintenance of the device inside the heating chamber  1 ′, but in normal state (including a state of heating a glass substrate) the cover  2 ′ is in a closed state, so that the heating chamber  1 ′ forms an airtight space. The structure of such heating chamber is also applicable to the present disclosure. 
     The heating operation of the heating apparatus is as following. Firstly, a glass substrate is put into the heating chamber  1 ′ in such a way that the glass substrate faces the heating unit  3 ′ and is supported on the plurality of supporting pins  4 ′, and then the glass substrate is heated by the heating unit  3 ′. Such heating operation requires physical contact between the glass substrate and the supporting pins, and this will cause not only hard collision and friction on the substrate and thus result in damages to the substrate, but also a temperature difference between portions of the substrate in contact with the supporting pins  4 ′ and other portions, of the substrate so that the glass substrate is non-uniformly heated. 
     SUMMARY 
     Embodiments of the present disclosure provide a substrate heating apparatus, which can avoid collision and friction on the substrate, and ensure uniform heating of the substrate. 
     According to the present disclosure, there is provided a substrate heating apparatus, which comprises: a heating unit, and a suspension holding unit located on the heating unit and hold the substrate above the heating unit in suspension. 
     In an example, the suspension holding unit comprises: a gas-flow supporting unit for blowing a gas toward the substrate so that the substrate is held above the heating unit in suspension. 
     In an example, the gas-flow supporting unit comprises: a gas source, a gas blower connected with the gas source, and a gas feeding channel connected with the gas blower, the gas feeding channel is provided in the heating unit, and the gas blower blows a gas flow through the gas feeding channel, and the gas flow blew from the gas feeding channel has a flowing direction toward the substrate. 
     In an example, the gas feeding channel comprises a first gas feeding channel and a second gas feeding channel interconnected to each other with their axes perpendicular to each other; the first gas feeding channel is connected with the gas blower, and the axis of the second gas feeding channel is oriented perpendicular to the surface of the substrate. 
     In an example, the gas-flow supporting unit further comprises: a gas heater provided between the gas source and the gas blower, the gas heater has a first side connected with the gas source and a second side connected with the gas blower. 
     In an example, the gas-flow supporting unit further comprises: a gas retrieving unit connected with the gas source and retrieving a gas flow flowing out of the gas feeding channel. 
     In an example, the gas retrieving unit comprises: a pump connected with the gas source, and a gas retrieving channel connected with the pump; the gas retrieving channel is provided in the heating unit, and the pump draws a gas flow through the gas retrieving channel toward the heating unit. 
     In an example, the gas retrieving channel comprises a first gas retrieving channel and a second gas retrieving channel interconnected to each other with their axes perpendicular to each other; the first gas retrieving channel is connected with the pump, and the axis of the second gas retrieving channel is oriented perpendicular the surface of the substrate. 
     In an example, the gas blower has a gas feeding pressure greater than a gas drawing pressure of the pump. 
     In an example, the second gas feeding channel and the second gas retrieving channel are provided adjacent to each other. 
     In an example, the substrate heating apparatus further comprises a heating chamber, wherein the heating unit and the suspension holding unit are located in the heating chamber; the suspension holding unit further comprises: suction cups for gripping the substrate by suction so that the substrate is held above the heating unit in suspension; the suction cups are provided at an upper portion of the heating chamber, and the heating unit is provided at the bottom of the heating chamber. 
     In an example, the suction cups are distributed along the periphery of the substrate. 
     In an example, the suction cups are expandable and retractable with an expandable-and-retractable direction perpendicular to the surface of the substrate. 
     In an example, the substrate heating apparatus further comprises at least two opposing stopper units on a side inside surface of the heating chamber for controlling positioning of the substrate relative to the heating unit. 
     In an example, the stopper units are expandable and retractable. 
     The substrate heating apparatus according to the embodiment of the present disclosure comprises: a heating unit and a suspension holding unit for holding the substrate above the heating unit so that there is no physical contact between the substrate and the heating unit. In this way, it can not only avoid collision and friction on the substrate and thus decreasing the damage to the substrate, but also ensure uniform heating of the substrate as the substrate is heated by the heating unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to clearly illustrate the technical solutions of the present disclosure or the prior art, the drawings for the description of the technical solutions according to the disclosure or the prior art will be briefly described as below. It is obvious that the described drawings are only illustrative explanations of some specific implementations of the technical solutions of the disclosure. Based on these drawings, those skilled in the art can obtain other drawing(s), without any inventive work. 
         FIG. 1  is a schematic view of a conventional heating apparatus; 
         FIG. 2  is an enlarged schematic view of a supporting pin in  FIG. 1 ; 
         FIG. 3  is a perspective view of a substrate heating apparatus according to an embodiment of the present disclosure; 
         FIG. 4  is a side view of the substrate heating apparatus according to the embodiment of the present disclosure; 
         FIG. 5  is a top view of the substrate heating apparatus according to the embodiment of the present disclosure; 
         FIG. 6  is a side sectional view of a gas feeding channel according to an embodiment of the present disclosure; 
         FIG. 7  is a side sectional view of another gas feeding channel according to an embodiment of the present disclosure; 
         FIG. 8  is a side sectional view of a gas retrieving channel according to an embodiment of the present disclosure; 
         FIG. 9  is a side sectional view of another gas retrieving channel according to an embodiment of the present disclosure; 
         FIG. 10  is a top view of a first heating unit according to an embodiment of the present disclosure; 
         FIG. 11  is a top view of a second heating unit according to an embodiment of the present disclosure; and 
         FIG. 12  is a top view of a third type heating unit according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Below, the technical solutions in the embodiments of the present disclosure will be described in a clearly and fully understandable way in connection with the drawings related to the embodiments of the disclosure. It is obvious that the described embodiments are just a part but not all of the embodiments of the disclosure. Based on the described embodiments herein, those skilled in the art can obtain other embodiment(s), without any inventive work, which should be within the scope of the disclosure. 
     Unless otherwise defined, technical jargon or scientific terms used herein should be interpreted in the usual sense as understood by those ordinary skilled in the relevant art of the present disclosure. The terms “first”, “second”, and the like, used in the specification and claims of this patent application of the disclosure, do not denote any order, quantity, or importance, but are used to distinguish among different integral parts. Likewise, the words “a” or “an” or the like, herein do not denote a limitation of quantity, but denote the presence of at least one of the referenced item. The terms “connection” or “interconnection” or the like, are not limited to physical or mechanical connections, but can comprise electrical connection, whether direct or indirect. The terms “upper”, “lower”, “left”, “right” and the like, are only used to indicate a relative positional relationship, which can be varied with a change of an absolute position of a described object. 
     The substrate heating apparatus according to an embodiment of the present disclosure comprises: a heating unit and a suspension holding unit for holding the substrate above the heating unit in suspension. 
     Since the substrate is held above the heating unit in suspension, therefore it has no physical contact with the heating unit. This can avoid collision and friction on the substrate, thus decreasing damage to the substrate, and ensuring uniform heating of the substrate by the heating unit. For the skilled in the art to better understand and implement the present disclosure, the embodiment of the present disclosure will be described in detail as below with reference to  FIGS. 3-12 , by explaining the implementation of holding a glass substrate in suspension. It should be understood that, the present disclosure is also applicable to hold devices or components other than the glass substrate. 
       FIG. 3  is a schematic view of a substrate heating apparatus according to an embodiment of the present disclosure. As shown in  FIG. 3 , the heating apparatus comprises: a heating unit  3  and a suspension holding unit. The heating unit  3  and the suspension holding unit can be disposed in a heating chamber  1 , and this increases heating efficiency. A glass substrate (not shown), for example, is placed in the heating chamber  1 . The heating unit  3  is provided at the bottom of the heating chamber  1 . The suspension holding unit can be a gas-flow supporting unit which blows gas flow toward the glass substrate so that the glass substrate is held above the heating unit  3  in suspension by means of gas-flow supporting. The force applied by the gas flow on the glass substrate is constant and equal to the gravity of the glass substrate so that the glass substrate is held in stable suspension. In specific implementations, the heating chamber in the embodiment of the present disclosure can be optionally provided or not provided depending on different needs. 
     The suspension holding unit in the embodiment of the present disclosure can comprise any means which can hold the substrate in suspension other than the gas-flow supporting unit, and the present disclosure is not limited in this regard. 
     As shown in  FIG. 4  and  FIG. 5 , the gas-flow supporting unit for example comprise: a gas source (not shown in the Figures), a gas blower  5  connected with the gas source, and a gas feeding channel  30  and  31  connected with the gas blower  5 . The gas feeding channels  30  and  31  are provided in the heating unit  3 , and the gas blower  5  blows a gas flow through the gas feeding channel  31  toward the glass substrate  7 . 
     With reference to  FIG. 4  as well as  FIG. 6  or  FIG. 7 , the gas feeding channel comprises a first gas feeding channel  30  and a second gas feeding channel  31 , which are interconnected and their axes are perpendicular to each other. The first gas feeding channel  30  is connected with the gas blower  5 , and the second gas feeding channel  31  is oriented toward the glass substrate  7 . The gas flow passes firstly through the first gas feeding channel  30  and then turns and flows out of the second gas feeding channel  31 . Thus, the gas flow is blew toward the glass substrate  7  in a roundabout way, and this prevents the glass substrate  7  from being damaged by a large impact force which would be otherwise introduced by a direct strike by the gas flow onto the glass substrate  7 . 
     The first gas feeding channel  30  can be a channel running-through the heating unit  3 , as shown in  FIG. 6 , or can be channels which do not completely run through the heating unit  3 , as shown in  FIG. 7 . Each first gas feeding channel  30  connects with a plurality of second gas feeding channels  31 . Alternatively, a plurality of first gas feeding channels  30  connect with one second gas feeding channel  31 . Alternatively, the heating unit  3  has a hollow center portion which forms the first gas feeding channel  30  and a plurality of second gas feeding channels  31  connected with the hollow center portion. 
     Since the heating unit  3  serves to heat the glass substrate  7  to a certain temperature, as the gas blower  5  blows gas into the gas feeding channel in the heating unit  3 , in order to prevent the temperature of the blew gas from affecting the temperature of the heating unit  3 , the temperature of the gas and the temperature of the heating unit  3  are made to be the same or similar. To achieve this purpose, the embodiment of the present disclosure has two implementations as following. 
     In a first implementation, a gas heater is provided between the gas source and the gas blower  5 , so that the gas passes through the heater before being blew into the gas feeding channel, and reaches to a same or similar temperature of the heating unit  3 . Certainly, the gas heater is not limited to the above-described arrangement. For example, the gas heater can be provided between the gas blower  5  and the first gas feeding channel  30 . 
     In a second implementation, a gas retrieving unit connected with the gas source is provided so that a gas flow cycling channel is formed. Since a gas flow that flows out of the gas feeding channel after being heated by the heating unit  3  has a temperature that is the same or similar as the temperature of the heating unit  3 , the gas flow is retrieved by the gas retrieving unit so that the retrieved gas flow can again be blew into the gas feeding channel by the gas blower, thereby effectively utilizing the gas flow and saving resources. 
     For a better understanding of this, the present disclosure will be further explained in the second implementation. 
     In the second implementation described above, the gas retrieving unit specifically comprises: a pump  6  as shown in  FIG. 5 , and a gas retrieving channel connected with the pump  6 . The gas retrieving channel is provided in the heating unit  3 , and the pump  6  draws a gas flow through the gas retrieving channel toward the heating unit. 
     As shown in  FIG. 8  or  FIG. 9 , the gas retrieving channel specifically can also comprises a first gas retrieving channel  32  and a second gas retrieving channel  33  interconnected with each other and their axes are perpendicular to each other. The first gas retrieving channel  32  is connected with the pump  6 , and the second gas retrieving channel  33  is oriented toward the substrate  7  so that the pump  6  draws a gas flow from the second gas retrieving channel  33  and the first gas retrieving channel  32  sequentially into the gas source, then is blew into the gas feeding channel again by the gas blower  5 , thus forming a gas cycling flow channel. 
     The first gas retrieving channel  32  can be a channel running through the heating unit  3  as shown in  FIG. 8 , or can be channels which do not run completely through the heating unit  3  as shown in  FIG. 9 . Moreover, each first gas retrieving channel  32  connects with a plurality of second gas retrieving channels  33 . Alternatively, a plurality of first gas retrieving channels  32  connect with one second gas feeding channel  31 . 
     In case that there is only a gas flow blew into the heating chamber  1 , the glass substrate  7  might float up and down in the gas flow, thus affecting the heating effect. In order to avoid such phenomenon, the gas retrieving unit as described above can also keep the suspended glass substrate  7  always in a stable state during a heating process in addition to the function of retrieving the gas flow. 
     In order to ensure that the glass substrate  7  is always suspended above the heating unit  3 , the gas feeding pressure of the gas blower  5  is greater than the pumping pressure of the pump  6 . The gas blower  5  and the pump  6  can be integrated into a single device, thus reducing the number of components of the substrate heating apparatus. 
     The second gas feeding channel  31  (also can be referred as a positive-pressure hole) and the second gas retrieving channel  33  (also can be called as a negative-pressure hole) are provided adjacent to each other. This can ensure the gas pressure in all second gas feeding channels  31  and regions in vicinity consistent, and it in turn can ensure that the glass substrate  7  is stably suspended above the heating unit  3 , thereby avoiding tilting of the glass substrate  7  and resultant non-uniform heating. 
     The configuration that the second gas feeding channel  31  and the second gas retrieving channel  33  are provided adjacent to each other can be in an arrangement as shown in  FIG. 10 , in which the second gas retrieving channels  33  are provided circumferentially around the second gas feeding channel  31 . Alternatively, the configuration can be in an arrangement as shown in  FIG. 11  in which the second gas feeding channel  31  and the second gas retrieving channel  33  are provided in a cross shape, and the second gas feeding channel  31  and the second gas retrieving channel  33  are disposed alternately along transverse and longitudinal directions of the cross. Alternatively, the configuration can be in an arrangement as shown in  FIG. 12  in which the second gas feeding channel  31  and the second gas retrieving channel  33  are disposed alternately along the vertical and horizontal directions. Alternatively, the configuration can be in an arrangement that combines any two or three of the above-mentioned arrangements. In addition, the second gas feeding channel  31  and the second gas retrieving channel  33  can have a cross sectional shape of a rectangular, a T-shape or funnel-shape. Certainly, the above-described arrangements and hole shapes are only examples, and the embodiment of the present disclosure is not limited thereto. 
     As shown in  FIG. 3 , the suspension holding unit in the embodiment of the present disclosure also can comprise suction cups (not shown) for sucking the glass substrate provided at an upper portion of the heating chamber, for example, on an inner surface of the cover  2  of the substrate heating apparatus, i.e., the inner top surface  20  of the heating chamber  1 . After the glass substrate is conveyed into the heating chamber  1 , the gas-flow supporting unit holds the glass substrate above the heating unit  3  in suspension, and the suction cups grip the glass substrate by suction so that, the glass substrate can be held above the heating unit in suspension  3  more stably, which further ensures the heating effect. 
     In addition, as the glass substrate is suspended by the cooperative actions of the gas-flow supporting unit and the suction cups, since the suction cups apply a suction force onto the glass substrate along a direction opposite to the gravity of the substrate, the supporting force given by the gas flow to the glass substrate is supplemented. Therefore, this can reduce simultaneously the gas feeding pressure of the gas blower  5  and the pumping pressure of the pump  6  as shown in  FIG. 5 , thereby reducing the power consumption of the gas blower  5  and the pump  6 . 
     Because the surface flatness of the glass substrate has a considerable influence on the liquid crystal display panel, in order to avoid affecting the display quality of the liquid crystal panel, a plurality of suction cups are distributed along the periphery of the glass substrate, thus ensuring that the suction cups do not contact the display region of the glass substrate  7 . 
     The above-described suction cups are expandable, and their expansion and retraction direction is perpendicular to the surface of the glass substrate  7 . Thus when the glass substrate  7  is conveyed into the heating chamber  1 , the suction cups can be in a retracted state to avoid a collision between the glass substrate  7  and the suction cups. And after the glass substrate  7  is centered with respect to the heating unit  3 , the suction cups can expand and grip the glass substrate. 
     Again with reference to  FIG. 4  or  FIG. 5 , in the embodiment of the present disclosure, at least two opposing stopper units  4  for controlling the position of the substrate  7  relative to the heating unit  3  can be provided on side surfaces inside the heating chamber  1 . After the glass substrate  7  is conveyed into the heating chamber  1 , the glass substrate  7  and the heating unit  3  can be placed exactly opposite to each other using the stopper units  4 , which can improve the heating effect. 
     The stopper units  4  can be expandable and retractable. Since the glass substrate  7  has various types and thus they have different dimensions, the expandable-and-retractable stopper units  4  can accommodate the glass substrates  7  with different dimensions within the same heating apparatus. 
     Although not shown, in order to facilitate conveying the glass substrate  7 , a side surface of the heating chamber  1  is a movable wall that can be opened; thus after the movable wall is opened, a robotic arm can convey the glass substrate  7  from the opening into the heating chamber  1 , and then close the movable wall. 
     The heating unit  3  can be made of a material with a high thermal conductivity so as to ensure temperature uniformity during heating. Although not shown, the above-described expandable-and-retractable stopper units  4 , the expandable-and-retractable suction cups, as well as the movable wall can be implemented by a pneumatic or electric-controlled means. 
     The above embodiments are only intended to be illustrative but not to limit the present disclosure. A variety of modifications and variations can be made by the ordinary skilled in the related art, without departing from the spirit and the scope of the present disclosure; thus, all equivalent technical solutions should be within the scope of the present disclosure, and the scope of the present disclosure should be defined by the claims.