Patent Publication Number: US-9839106-B2

Title: Flat-panel-display, bottom-side, electrostatic-dissipation

Description:
CLAIM OF PRIORITY 
     This is a continuation-in-part of U.S. patent application Ser. No. 14/739,712, filed on Jun. 15, 2015, which claims priority to U.S. Provisional Patent Application Nos. 62/028,113, filed on Jul. 23, 2014, and 62/079,295, filed on Nov. 13, 2014, all of which are hereby incorporated herein by reference in their entirety. 
     This is a continuation-in-part of U.S. patent application Ser. No. 14/920,659, filed on Oct. 22, 2015, which claims priority to U.S. Provisional Patent Application Nos. 62/088,918, filed on Dec. 8, 2014, 62/103,392, filed on Jan. 14, 2015, 62/142,351, filed on Apr. 2, 2015, and 62/159,092, filed on May 8, 2015 which are hereby incorporated herein by reference in their entirety; and is a continuation-in-part of U.S. patent application Ser. No. 14/739,712, filed on Jun. 15, 2015, which claims priority to U.S. Provisional Patent Application Nos. 62/028,113, filed on Jul. 23, 2014, and 62/079,295, filed on Nov. 13, 2014. 
     This claims priority to U.S. Provisional Patent Application Ser. Nos. 62/079,295, filed on Nov. 13, 2014, 62/088,918, filed on Dec. 8, 2014, 62/103,392, filed on Jan. 14, 2015, 62/142,351, filed on Apr. 2, 2015, and 62/159,092, filed on May 8, 2015 which are hereby incorporated herein by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The present application is related generally to use of x-rays for electrostatic dissipation of a bottom-side of a flat-panel-display (FPD) during manufacture of the FPD. 
     BACKGROUND 
     Static electric charges on some materials, such as electronic components for example, can discharge suddenly, resulting in damage to the material. For example, static electric charges can build up on flat-panel-displays (FPD for singular or FPDs for plural) during manufacture. Static charges on a bottom side of the FPD can discharge to a support table when the FPD is lifted off of the table, causing damage to the bottom side of the FPD. It can be beneficial to provide a conductive path with proper resistance level for a gradual dissipation of such charges. Gradual dissipation of these static charges can avoid damage to sensitive components. 
     SUMMARY 
     It has been recognized that it would be beneficial to provide a conductive path with proper resistance level for a gradual dissipation of static charges on various materials, including a bottom side of a flat-panel-display (FPD for singular or FPDs for plural). The present invention is directed to various embodiments of methods and FPD manufacturing machines, with electrostatic dissipation of a bottom side of an FPD during manufacture of the FPD, that satisfy these needs. Each embodiment may satisfy one, some, or all of these needs. 
     The FPD manufacturing machine can comprise a table, a lift-pin, and an actuator. The table can have a hole. The lift-pin can be movably located in the hole. The actuator can exert a force on the lift-pin to at least assist in causing the lift-pin to lift the FPD off of the table. The table can be configured for mounting an x-ray tube for dissipation of static electricity on a bottom side of the FPD during manufacture of the FPD. 
     The method can comprise lifting the FPD off of a table and emitting x-rays between the FPD and the table when the FPD is lifted off of the table in order to ionize air to cause electrostatic dissipation of static charges on a bottom side of the FPD. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1 a -4 c    are schematic, cross-sectional side-views of a flat-panel-display (FPD)  13 , and FPD manufacturing machines  10 ,  20 ,  30 , and  40 , in accordance with embodiments of the present invention.  FIGS. 1 a , 2 a , 3 a , and 4 a    show an FPD  13  supported by a table  12 .  FIGS. 1 b , 2 b , 3 b , and 4 b    show the FPD  13  raised off of the table  12  and supported by lift-pins  19 .  FIGS. 1 c , 2 c , 3 c   , and  4   c  are top views of FPD manufacturing machines  10 ,  20 ,  30 , and  40 , respectively, without the FPD  13 . 
         FIGS. 1 a - c    show each lift-pin  19  movably located a first hole  18   f  and each x-ray tube  11  mounted, fixed and stationary with respect to the table  12 , inside a second-hole  18   s . 
         FIGS. 2 a - c    show that the x-ray tubes  11  can form at least a vertical segment of and can be movable along with the lift pins  19 . 
         FIGS. 3 a - c    show that the lift-pins  19  can each be a lift-cylinder  19   c  with a hollow-core. Each x-ray tube  11  can be located inside the hollow-core of a lift-cylinder  19   c  and can be mounted fixed and stationary with respect to the table  12 . 
         FIGS. 4 a - c    show that the x-ray tubes  11  can be located around at least a portion of a periphery of the table  12  and can be positioned to emit x-rays  17  between the table  12  and the FPD  13 . 
         FIG. 5  is a schematic, cross-sectional side-view of an x-ray tube  11  that can provide a 360° emission of x-rays around a circumference of the x-ray tube  11 , and that has a cathode  51  with electron emitter  51   e , and an anode  52  with a protrusion or convex surface, such as a hemisphere or a half-ball-shape, extending towards the cathode  21  or electron emitter  51   e . 
     
    
    
     DEFINITIONS 
     As used herein, the term “electrostatic discharge” means a rapid flow of static electricity from one object to another object. Electrostatic discharge can result in damage to electronic components. 
     As used herein, the term “electrostatic dissipation” means a relatively slower flow of electricity from one object to another object. Electrostatic dissipation usually does not result in damage to electronic components. 
     As used herein, the term “composite material” means a material that is made from at least two materials that have significantly different properties from each other, and when combined, the resulting composite material has different properties than the individual materials. Composite materials typically include a reinforcing material embedded in a matrix. One type of a composite material is carbon fiber composite which includes carbon fibers embedded in a matrix. Typical matrix materials include polymers, bismaleimide, amorphous carbon, hydrogenated amorphous carbon, ceramic, silicon nitride, boron nitride, boron carbide, and aluminum nitride. 
     DETAILED DESCRIPTION 
     Shown in  FIGS. 1 a -4 c    are flat-panel-display (FPD for singular or FPDs plural) manufacturing machines  10 ,  20 ,  30 , and  40 , each comprising a table  12 , lift-pins  19 , at least one actuator  15 , and x-ray tubes  11 . Shown in  FIGS. 1 a , 2 a , 3 a , and 4 a    are FPDs  13  supported by the table  12 . At least one lift-pin  19  can at least assist in lifting the FPD  13  off of the table  12 . Shown in  FIGS. 1 b , 2 b , 3 b   , and  4   b  are FPDs  13  supported by the lift pins  19  above the table  12 . Shown in  FIGS. 1 c , 2 c , 3 c , and 4 c    is a top view of the table  12 , the lift pins  19 , and the x-ray tubes  11  without the FPD  13 . 
     Electrostatic charges can build up on the FPD  13  during manufacture of the FPD  13 . Rapid electrostatic discharge of such electrostatic charges can cause damage to the FPD  13 . Relatively slower electrostatic dissipation of such electrostatic charges can avoid this damage. Various methods have been used for electrostatic dissipation of electrostatic charges on a top side  13   t  of the FPD  13 . Electrostatic dissipation at an opposite, bottom side  13   b  of the FPD  13  can be more difficult because the table  12 , used to support the FPD  13 , can block electrostatic dissipation equipment. Damage to the bottom side  13   b  of the FPD  13 , due to electrostatic discharge, typically occurs as the FPD  13  is raised off of the table  12  by the lift-pins  19 . 
     As shown in  FIGS. 1 a -4 c   , one or more x-ray tubes  11  can be located to emit x-rays  17  between the table  12  and the bottom side  13   b  of the FPD  13  when lifting the FPD  13  off of the table  12 . The x-rays  17  can be soft or low-energy x-rays. These x-rays  17  can form ions in air between the FPD  13  and the table  12 . The ions can gradually dissipate electrostatic charges on the bottom side  13   b  of the FPD  13 , thus avoiding rapid electrostatic discharge at, and damage to, the bottom side  13   b  of the FPD  13 . These designs can allow electrostatic dissipation of the difficult-to-access bottom side  13   b  of the FPD  13 . The FPD manufacturing machines  10 ,  20 ,  30 , and  40  can also include a controller  22  configured to cause the x-ray tube(s)  11  to emit the x-rays  17  between the FPD  13  and the table  12  when the lift-pin(s)  19  lift the FPD  13  off of the table  12 . The controller  22  can include a power supply or power supplies for the x-ray tubes  11 . 
     The table  12  can include an electrically-insulative outer-layer  12   i  located to face and contact the FPD  13 . The table  12  can also include one or more holes  18 . Each hole  18  can extend through the table  12 . Each lift-pin  19  can be movably located in a hole  18 . There can be an air gap around each lift-pin  19  to allow the lift-pin  19  can move freely in the hole  18 . The actuator(s)  15  can exert a force on each lift-pin  19  to cause the lift-pins  19  to lift the FPD  13  off of the table  12 . 
     The table  12  can be configured for mounting x-ray tube(s)  11  for dissipation of static electricity on a bottom side  13   b  of the FPD  13  during manufacture of the FPD  13  by one or more of the following:
     1. The holes  18  in the table  12  can include one or more first holes  18   f  and one or more second holes  18   s . Each lift-pin  19  can be located in one of the first hole(s)  18   f . Each second hole  18   s  can be free of any lift-pin  19  configured to at least assist in lifting the FPD  13 . The second hole(s)  18   s  can be reserved for x-ray tube(s)  11 , as will be described below in reference to  FIGS. 1 a   - c.      2. The lift-pin(s)  19  can have a section reserved for adding the x-ray tubes  11 . This section can be a vertical section of or even the entire lift-pin(s)  19 , as will be described below in reference to  FIGS. 2 a - c   ; or this can be a hollow-core, as will be described below in reference to  FIGS. 3 a   - c.      3. The table  12  can include frames  41  for mounting the x-ray tubes  11 , as will be described below in reference to  FIGS. 4 a   - c.      

     As shown in  FIGS. 1 a - c   , the hole(s)  18  can include at least one first hole  18   f  and at least one second hole  18   s . The lift-pin(s)  19  can be movably located in a first hole  18   f  but not in a second hole  18   s . The x-ray tube(s)  11  can be mounted, fixed and stationary with respect to the table  12 , inside a second hole  18   s . The table  12  can have a bearing-surface  12   s  for holding the FPD  13 . In one aspect, an x-ray emission-end of the x-ray tube(s)  11  can be located from flush with, to a distance d of up to 10 millimeters below, the bearing-surface  12   s  of the table  12 . 
     As shown in  FIGS. 2 a - c   , the x-ray tube(s)  11  can form a portion of a length L (i.e. a vertical segment) of the lift-pin  19  (see lift-pin  19  and x-ray tube  11  on the left side of  FIGS. 2 a - b   ). The x-ray tube  11  can be the entire lift-pin  19  (see lift-pin  19  and x-ray tube  11  on the right side of  FIGS. 2 a - b   ). The x-ray tube(s)  11  can be moveable along with the lift-pin(s)  19 . Thus, the x-ray tube(s)  11  can be used to at least assist in lifting the FPD  13 . 
     A spacer  14  can be located at an x-ray emission-end one or more of the x-ray tubes  11 . The spacer  14  can be a vertical segment of the lift-pin(s)  19 . The spacer  14  can maintain a predetermined distance D (e.g. between 3-10 millimeters) between the x-ray emission-end of the x-ray tube(s)  11  and the FPD  13  when lifting the FPD  13 , thus allowing space for the x-rays  17  to spread out and form ions. 
     It can be important to avoid electrical current flow from the x-ray tube(s)  11  to the FPD  13 . The spacer  14  can be electrically-insulative to electrically insulate the x-ray tube(s)  11  from the FPD  13 . The spacer  14  can include or can be a polymer, such as polyether ether ketone (PEEK). 
     The spacer  14  can be hollow to form a region for formation of ions. The spacer  14  can be vented to allow passage of the ions and x-rays  17  outward from the spacer  14 . The spacer  14  can be at least part of a shell, a hollow region of the shell extending beyond the emission-end of the x-ray tube(s)  11 , a cap, or combinations thereof, as described in U.S. patent application Ser. No. 14/920,659, filed on Oct. 22, 2015, incorporated herein by reference. 
     As shown in  FIGS. 3 a - c   , one or more of the lift-pins  19  can each be a lift-cylinder  19   c , each with a hollow-core. An x-ray tube  11  can be located inside the hollow-core of each of the lift-cylinders  19   c , and can be mounted fixed and stationary with respect to the table  12 , such as by a mount  16 . The lift-cylinders  19   c  can comprise a material that is strong enough for lifting the table  12  and can be substantially transmissive to soft x-rays, such as carbon fiber composite for example. The lift-cylinders  19   c  can be vented with holes or channels to allow ions and/or x-rays  17  to more easily pass outside of the hollow-core of the lift-cylinders  19   c . 
     As shown in  FIGS. 4 a - c   , one or more the x-ray tubes  11  can be located around all or a portion of a periphery of the table  12  and positioned to emit x-rays  17  between the table  12  and the FPD  13  when the FPD is raised. The x-ray tubes  11  can circumscribe the table  12 . The x-ray tube(s)  11  can be oriented substantially parallel with the bearing-surface  12   s  of the table  12 . As shown in  FIG. 4 c   , the x-ray tube(s)  11  can be attached to the table  12 , or to some other device, by frame(s)  41 . 
     Each design has its advantages and disadvantages which can be considered for each situation or FPD manufacturing machine. An advantage of the designs of  FIGS. 1 a -3 c    over the design of  FIGS. 4 a - c    can be emission of x-rays  17  in a center region of the FPD  13 . An advantage of the design of  FIGS. 4 a - c    over the designs of  FIGS. 1 a -3 c    can be ease of installation of the x-ray tube(s)  11 , i.e. no changes are needed to hole(s)  18  in the table  12  or to the lift-pin(s)  19 . An advantage of the design of  FIGS. 1 a - c    over the designs of  FIGS. 2 a -3 c    can be increased flexibility of potential x-ray tube location(s), and thus possibly improved electrostatic dissipation. An advantage of the designs of  FIGS. 1 a - c    &amp;  3   a - c  over the design of  FIG. 2 a - c    can be broader angle of x-ray emission before reaching the table  12  because the x-ray tube(s)  11  are not raised as the lift-pin(s) raise; however the design of  FIGS. 2 a - c    may be preferred if each x-ray tube  11  gives a 360° emission of x-rays  17  around a circumference of the x-ray tube  11 . Cost, potential blocking of x-rays  17 , and lift-pin  19  strength, can be considered in deciding between the various designs. A combination of the above designs can also be used. 
     Shown in  FIG. 5  is an example of an x-ray tube  11  that can provide a 360° emission of x-rays around a circumference of the x-ray tube  11 . The x-ray tube  11  can include a cathode  51  and an anode  52 . The cathode  51  can include an electron emitter  51   e  which can be configured to emit electrons  58  towards the anode  52  due to heat and/or due to a large voltage differential between the cathode  51  and the anode  52 . The anode  52  can be configured to emit x-rays  17  outward from the x-ray tube  11  in response to the impinging electrons  58  from the electron emitter  51   e . For example, the electrons  58  can excite atoms in a target material on the anode  52 , causing these atoms to emit x-rays  17 . 
     The anode  52  can have a protrusion or convex surface, such as a hemisphere or a half-ball-shape, extending towards the cathode  21  or electron emitter  51   e . The protrusion can improve voltage gradients, making easier emission of electrons  28  to the anode  22 , and can allow 360° emission of x-rays  17 . The convex surface can include the target material, e.g. tungsten. The anode  52  can be made of or can comprise various materials, such as for example refractory metals, tungsten, metal carbide, metal boride, metal carbon nitride, and/or noble metals. 
     The x-ray tube  11  can include an enclosure  53  that can be annular-shaped. The enclosure can be made of a strong material (e.g. a composite material) to allow the enclosure  53  to hold at least a portion of the weight of the FPD  13 . The enclosure  53  can be electrically-conductive or electrically-insulative. If the enclosure is electrically-conductive, it can be insulated from the cathode  51  by an electrically-insulative material  55 . 
     The enclosure  53  can include a window  56  that is annular-shaped to allow x-rays  17 , generated at the anode  52 , to emit outwards in a 360° arc in a latitudinal direction outward from the x-ray tube  11 . A 360° emission of x-rays  17  can be effective at forming a large number of ions between the FPD  13  and the table  12 , resulting in effective electrostatic dissipation of the FPD  13 . The window  56  can be one part of the enclosure  53  or can be the entire enclosure  53 . 
     The window  56  can be made of or can comprise various materials, such as for example carbon fiber composite, graphite, plastic, glass, beryllium, and/or boron carbide. Advantages of using a carbon fiber composite include low atomic number, high structural strength, and high electrical conductivity. 
     The window  56  can be electrically conductive and can be electrically coupled to the anode  52 . The enclosure  53  can be electrically conductive and can be electrically coupled to the window  56  (or the window  56  can form the entire enclosure  53 ). A power supply  54  can be electrically coupled to the cathode  51  and electrically coupled to the enclosure  53 . The electrical coupling from the power supply  54  to the enclosure can be through a ground. Thus, electrons can flow from the power supply  54  to and through the cathode  51 , from the cathode  51  to the anode  52  and from the anode  52  through the enclosure  53  back to the power supply  54 . 
     The x-ray tube  11  can include a connector  57  for attaching the x-ray tube  11  to the lift-pin  19 , or for attaching the x-ray tube  11  directly to the actuator  15 , if the x-ray tube  11  is the entire lift-pin  19 . The connector  27  can be threaded, a sleeve connector, a BNC connector, or other type of connector. 
     Methods of electrostatic dissipation of a bottom side of a flat-panel-display (FPD) during manufacture of the FPD  13  can include some or all of the following steps, which can be performed in the order shown, or other order. The devices described in the methods, including the table  12 , the lift-pin(s)  19 , the lift-cylinder(s)  19   c , and the x-ray tube(s)  11 , can have characteristics as described above. 
     The method can include lifting the FPD  13  off of the table  12 , then emitting x-rays  17  between the FPD  13  and the table  12 . 
     In one embodiment, as shown in  FIGS. 1 a - b   , the table can have multiple holes  18 , including one or more first holes  18   f  and one or more second holes  18   s . The second hole(s)  18   s  are different from the first hole(s)  18   f . Lifting the FPD  13  can include using one or more lift-pins  19 , each of which can be located in a first hole  18   f  (usually one lift-pin  19  per each first hole  18   f ), to at least assist in lifting the FPD  13  off of the table  12 . Emitting x-rays  17  can include emitting the x-rays  17  from one or more x-ray tubes  11 , each located in a second hole  18   s  (usually one x-ray tube  11  per each second hole  18   s ). The second hole(s)  18   s  can be free of any lift-pin(s)  19  configured for lifting the FPD  13 . The x-ray tube(s)  11  can be mounted, fixed and stationary with respect to the table  12  during lifting of the FPD  13 . In one aspect, an x-ray emission-end of the x-ray tube(s)  11  can be located from flush with, to a distance d of up to 10 millimeters below, a bearing-surface  12   s  of the table  12 . 
     In another embodiment, as shown in  FIGS. 2 a - b   , lifting the FPD  13  can include using x-ray tube(s)  11  to at least assist in lifting the FPD  13  off of the table  12 . In one aspect, the x-ray tube(s)  11  can be configured to emit x-rays  17  radially outward and parallel to a bearing surface  12   s  of the table  12  and/or in a 360 degree arc around a circumference of the x-ray tube  11 . 
     In another embodiment, as shown in  FIGS. 3 a - b   , lifting the FPD  13  can include using at least one lift-cylinder  19   c  to at least assist in lifting the FPD  13  off of the table  12 . The lift-cylinder(s)  19   c  can each be located in a hole  18  in the table  12  (usually one lift-cylinder  19   c  per hole  18 ). Emitting the x-rays  17  can include emitting x-rays  17  from one or more x-ray tubes  11 , each located inside a hollow-core of one of the lift-cylinders  19   c . The x-ray tube(s)  11  can be fixed and stationary with respect to the table  12  during lifting of the FPD  13 . 
     In another embodiment, as shown in  FIGS. 4 a - b   , lifting the FPD  13  can include using one or more lift-pins  19 , each located in a hole  18  in the table  12  (usually one lift-pin  19  per hole  18 ), to at least assist in lifting the FPD  13  off of the table  12 . Emitting x-rays  17  can include emitting the x-rays  17  from one or more x-ray tubes  11  located around at least a portion of a periphery of the table  12 . The x-ray tube(s)  11  can circumscribe the table  12 . The x-ray tube(s)  11  can be oriented substantially parallel with a bearing-surface  12   s  of the table  12 . 
     It can be important, to avoid wasted electrical power, to avoid overheating the x-ray tube  11 , and to avoid early failure of the x-ray tube(s)  11 , for the x-ray tube(s)  11  to activate and emit x-rays  17  only while the FPD  13  is being lifted off of the table  12  and also possibly for a short time duration before and/or after lifting the FPD  13  off of the table  12 . For example, the controller  22  can be configured to actuate the x-ray tube(s)  11  no more than thirty seconds prior in one aspect, no more than one minute prior in another aspect, or no more than three minutes prior in another aspect, to the FPD manufacturing machine  10 ,  20 ,  30 , or  40  lifting the FPD  13  off of the table  12 . As another example, the controller  22  can be configured to terminate emission of the x-rays  17  no later than one minute in one aspect, no later than three minutes in another aspect, or no later than ten minutes in another aspect, after the FPD manufacturing machine lifted the FPD  13  off of the table  12 . 
     The term “x-ray tube” is used herein, because this is a standard term in this industry, but the x-ray tube(s)  11  are not necessarily cylindrical or tubular in shape.