Abstract:
Displays and methods of manufacturing displays are disclosed herein. An embodiment of a method of manufacturing a display comprises manufacturing a circuit board; forming a hole in a material; attaching the circuit board to the material, wherein the hole forms a cavity upon attachment of the circuit board to the material; and connecting a light source to the circuit board, the light source being located within the cavity.

Description:
BACKGROUND 
       [0001]    Light emitting diodes are used in many different applications. One such application are segment displays, such as seven segment displays. Due to construction techniques, the displays tend to be rather high, meaning that they extend rather high from the circuit board or substrate on which they are mounted. Many electronic devices that segment displays are becoming smaller, but the size is limited by the relatively large height of the segment displays. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0002]      FIG. 1  is a top plan view of an embodiment of a display. 
           [0003]      FIG. 2  is a top plan view of an embodiment of a digit used in the display of  FIG. 1 . 
           [0004]      FIG. 3  is a cut away view of an embodiment of the segment display of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0005]    Segment displays and methods of making segment displays are disclosed herein.  FIG. 1  is a top plan view of an embodiment of a display  100 . The display  100  described herein is a six digit, seven segment display; meaning that the display  100  has six digits  102  and digit has seven segments  104 . It is to be understood that the display  100  described herein is for exemplary purposes only and that other display formats may be used. 
         [0006]    Each digit has seven segments  104 , which enable all numerals to be displayed. As described in greater detail below, each of the segments  104  includes a cavity that has a light source, such as an light-emitting diode, located therein. When the light source emits light, the light is reflected so that the cavity or segment emits light in the shape of the cavity. Conventional displays cut the cavities into the substrate, which is difficult, especially as the size of the substrate decreases. 
         [0007]      FIG. 2  is a top plan view of a digit  130  as used in the display  100  of  FIG. 1 . The digit  130  has a plurality of segments  132 . The embodiment of the digit  130  has seven segments  132 . As described in greater detail below, the segments  132  are cavities within the display  100 , of  FIG. 1 . Each segment  132  has a light source  136  located within the cavity. The light sources  136  may be a light-emitting diodes (LEDs) and are sometimes referred to as LEDs  136 . Separation walls  140  are located between the segments  132 . The separation walls  140  serve to isolate the segments  132  to prevent light from a first segment from entering a second segment. By selectively lighting individual light sources  136 , different numbers or letters can be displayed in a conventional manner. 
         [0008]      FIG. 3  is a side cut away view of an embodiment of a segment display  100 . The embodiment of the display  100  includes a circuit board  144  and a material  148  attached to the circuit board  144 . In some embodiments an adhesive film  149  is located between the circuit board  144  and the material  148  and serves to attach the material  148  to the circuit board  144 . 
         [0009]    The circuit board  144  may be a rigid-type or flexible-type circuit board. The circuit board  144  has a first side  150  and a second side  152  located opposite the first side  150 . The first side  150  may serve as an exterior surface for the display  100 . The second side  152  is located proximate the material  148 . Electronic traces and the like are located on or within the circuit board  144 . For example, electronic traces may be located on the second side  152  of the circuit board  144 . The electronic traces serve to connect electronic components mounted to the circuit board  144  and the transmit signals throughout the circuit board  144 . In the embodiment of the circuit board  144  described herein, the circuit board  144  serves to provide electricity to at least one light source  136 , such as an LED (referred to herein as the LED  136 ), connected to the circuit board  144 . 
         [0010]    The embodiment of the circuit board  144  described herein has four layers as described below. A first layer  156  may be a solder mask or other non-conductive material. The first layer  156  serves as an insulator and covering for the display  100 . A second layer  160  may contain electrically conductive elements, such as traces and vias. The traces in the second layer  160  may serve to power the LED  136 . In an alternative embodiment, the second layer  160  may be a continuous conductive sheet and may serve as a ground plane. 
         [0011]    A third layer  162  may be an insulator, such as a polymide, or any other insulator used in printed circuit board fabrication. A fourth layer  164  may contain electrical elements, such as traces, and may work with the second layer  162  to provide power to the LED  136 . The first side  150  of the circuit board  144  is located on the first layer  156  and the second side  152  of the circuit board  144  is located on the fourth layer  164 . 
         [0012]    The fourth layer  164  also may have conductive pads  168  located thereon. The pads  168  may be made, as examples, of copper, aluminum, or nickle. Wires  170  connect the pads  168  to the LED  136 . The pads  168  may be placed on specific traces on the fourth layer  164  in order to conduct electricity to the LED  136 . As shown, the LED  136  is located in a cavity  172 . As described below, the cavity  172  forms the seven segments  132 . 
         [0013]    As stated above, some embodiments of the display  100  may use an adhesive film  149  to connect the circuit board  144  to the material  148 . The adhesive film  149  may also be referred to as a bonding film. The adhesive film  149  has a first side  174  and a second side  176  located opposite the first side  174 . The first side  174  of the adhesive film  149  is attached to the second side  152  of the circuit board  144 . In some embodiments, the first side  174  of the adhesive film comprises an adhesive and is adhered to the second side  152  of the circuit board  144 . In some embodiments, an adhesive may be applied to the second side  152  of the circuit board  144  or the first side  174  of the adhesive film and the adhesive  149  film may be subsequently adhered to the circuit board  144 . 
         [0014]    As described in greater detail below, the adhesive film  149  may have portions cut out so that the adhesive film  149  does not cover the pads  168 , the LED  136 , the wires  170 , or other contacts requiring electrical connections. In other embodiments, the adhesive film  149  may be a continuous sheet. Portions may be cut out of the continuous sheet in order to enable electrical connections to be made as required. 
         [0015]    The material  148  may comprise pre-molded polyphthalamide, liquid crystal polymer, FR-4, polyethene (PET) or other materials. In some embodiments, the material  148  is rigid and may be more rigid than the circuit board  144 . In some embodiments, the material  148  may be able to withstand high temperature, such as the temperature required to bond or solder components to the circuit board  144 . 
         [0016]    The material  148  has a first side  180  and a second side  182 . The first side  180  of the material  148  is located adjacent the second side  152  of the circuit board  144 . In embodiments using the adhesive film  149 , the adhesive film  149  may be adhered to the second side  152  of the circuit board  144  and the first side  180  of the material  148 . With additional reference to  FIG. 2 , the material  148  has cavities  172  formed therein that form the segments  132 . In the embodiment described herein, the cavities  172  extend between the first side  180  and the second side  182  and may be through holes. The cavities  172  may be virtually any shape and may be formed by drilling, die-set punch, or other methods. When the material  148  is adhered to the adhesive film  149 , the cavities  172  become the segments  132  of the display  100 . 
         [0017]    With additional reference to  FIG. 2 , the cavity  172  is shaped as the segment  132 . Therefore, when the LED  136  illuminates, the segment  132  illuminates. In order to direct light from the cavity  172 , the material  148  has walls  184  that may reflect light. The reflection also serves to increase the intensity of light emitted from the cavity  172 . The angle in which the walls  184  intersect the circuit board  144  affects the illumination provided by the display  100 . In some embodiments, the walls  184  intersect the circuit board  144  at a certain angle e.g. a forty-five degree angle. The material  148  and the walls  184  serve as the separation walls  140  between the segments  132 . 
         [0018]    The cavity  172  may be filled with an encapsulant. The encapsulant serves to protect the components located within the cavity  172 . In addition, the encapsulant may serve to diffuse the light emitted by the LED  136 . The diffusion evens the light emission from the cavity  172  so that all areas of the cavity  172  emit approximately the same intensity of light. A cover  190  may be placed over the cavity  172  and may adhere to the second side  182  of the material  148 . The portion of the cover  190  covering the cavity  172  may serve to further diffuse light emitted by the LED  136 . The portion of the cover  190  covering the material  148  may be a color that contrasts with the color of light emitted by the segments  132  so that the display  100  is easier to read. 
         [0019]    Fabrication of the display  100  consists of fabricating the circuit board  144  as described above. The material  148  is fabricated with holes in locations of the cavities  172 . The material  148  is then attached to the circuit board  144 . In some embodiments, the adhesive film  149  is used to adhere the material  148  to the circuit board  144 . In some embodiments, the adhesive film  149  is a continuous sheet and portions of the sheet proximate the cavities  172  are removed. In other embodiments, the adhesive film  149  is cut to fit the first side  180  of the material  148 , so no material needs to be removed after the material  148  is adhered to the circuit board  144 . The holes in the material  148  become cavities when the material  148  is attached to the circuit board  144 . 
         [0020]    The LED  136  and wires  170  may be connected to the circuit board  144  before or after the material  148  is bonded to the circuit board  144 . After the material  148  is bonded to the circuit board  144 , the encapsulant may be added to the cavity  172 . The cover  190  may then be added. Colors may be added to the cover  190  before or after it is attached to the material  148 . 
         [0021]    The display  100  described herein may be a very thin display. For example, the thickness of the display  100  between the cover  190  and the first surface  150  of the circuit board  144  may be approximately 0.6 millimeters or less. One reason for the thin display is the use of the material  148 , wherein holes are precut into the material  148 , so that cavities do not have to be cut after the material  148  is attached to the circuit board  144 .