1. Field of the Invention
The present invention relates to a method of manufacturing a particle-based image display, and more particularly, to a method of inspecting and repairing defects in the manufacturing process.
2. Description of the Related Art
Particle-based image display (PBD) technology has drawn a great deal of attention by those skilled in display technology in recent years. Due to its wide viewing angles, low power consumption, light weight, and thinness, PBDs are widely applied in a variety of products such as electronic readers, electronic paper, electronic tags, electronic signage, and the like. PBDs are capable of providing visual effects which are similar to that of reading paper products. Different from backlight-type flat panel displays, PBDs utilize reflected ambient light from pigment particles to display content, and thus, there is no glare or other effects resulting from strong external light which affect comfortable reading. In addition, PBDs consume power only when the displayed contents are subjected to change.
A PBD includes a plurality of independently addressable display units spatially arranged in the form of a matrix. Each display unit is formed with a plurality of display cells, where each display cell is filled with pigment particles. Each display unit is disposed between a pair of opposing, spaced-apart substrates, and electrodes are disposed on at least one substrate. By applying voltages onto the electrodes, the charged pigment particles in the cells migrate by attraction to the respective electrodes having opposite polarities as a result of an electric field generated between the pair of substrates. Thus, the locations of the pigment particles can be controlled by changing the polarities of the electrodes, thereby displaying images of the reflected light from the pigment particles or fluid.
In FIG. 1A to FIG. 1C, a method of manufacturing a dry powder type particle-based image display 100 is shown. A plurality of rib structures 122 are first formed on a substrate 110 to define a plurality of imaging cells 120. A plurality of first particles 130 and second particles 140 are then filled into the plurality of imaging cells 120 sequentially. After that, the plurality of imaging cells 120 are sealed with a back panel 150 on which electrodes 160 are formed. Each imaging cell 120 is filled with the plurality of first particles 130 and the plurality of second particles 140 having different colors in contrast (e.g., black and white) and having charges with opposite polarities, respectively.
Thus, the floating state and the falling state of the different colored particles 130, 140 in the imaging cells 120 are controlled by varying external electric fields imposed on the pigment particles, thereby achieving color image displaying with coordination of a color filter. In addition, in order to overcome the slow response drawbacks of electrophoretic displays, the pigment particles 130, 140 in the dry powder type displays are selected to have better flowability and floodability. As such, the pigment particles have the characteristics of fluidity, and thus move fast when driven by an electric field. However, during the filling process, the pigment particles 130, 140 may be dispersed or spread all over the cells, i.e., wherein the pigment particles 130, 140 are not dispersed along a straight line even under the effect of the gravity. If the pigment particles 130, 140 are not uniformly filled, the display 100 would generate color deviation in color image displaying so that the yield rate of the display would be reduced. In addition, the black and white colored particles having charges with opposite polarities may easily aggregate together because of electrostatic attraction, which makes it difficult to fill the pigment particles into the imaging cells and affects the production yield. Lowering the charge density of the pigment particles may reduce the electrostatic attraction generating particle aggregation; however, it will reduce the sensitivity of the pigment particles to a driving electric field, which results in slow responses. Otherwise, the pigment particles would need to be driven with high voltages. Indeed, it presents a great challenge for the filling of the particles process to uniformly fill the black and white colored particles having charges of opposite polarities in each display cell. Thus, quality control for the uniformity of the filling of the particles plays an important role in the fabricating process of the particle-based image display.
In the conventional manufacturing process of PBDs, most quality control steps are performed after sealing the plurality of imaging cells. Thus, even though defects are inspected, there is no way for repair. For example, U.S. Pat. No. 7,843,621 discloses a test method for use in the production of an electro-optic display, in which the only suggestion after defect inspection is to record the locations of defective cells, so as to ensure that the units are not used in final products. Though JP200603918 discloses a method of manufacturing a particle-based display, which includes an optical defect inspection procedure before sealing the front panel, no corresponding action is suggested to deal with the defects.
Therefore, a heretofore unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies.