Patent Application
20100239747
1. Field of the Invention
The invention relates in general to a shadow mask and an evaporation system incorporating the same, and more particularly, to a shadow mask capable of alleviating the particles adhered to the edge of the opening of the shadow mask from scratching or pressing the substrate and an evaporation system incorporating the same.
2. Description of the Related Art
Unlike an ordinary liquid crystal display (LCD) panel which illuminates through a backlight source, an OLED panel is current driven or voltage driven to illuminate. Therefore, the OLED panel is featured by self-luminance, full-color, and wide view-angle. The OLED panel may be further applied to portable electronic devices such as mobile phone and personal digital assistant (PDA) and has gained great potential.
A conventional OLED panel includes an upper cover and a thin film transistor (TFT) substrate. The upper cover is parallel to and coupled to the TFT substrate through a sealant. The TFT substrate includes a number of red pixels, blue pixels and green pixels and a number of organic electroluminescent devices (OELD). The OELDs are disposed in the red pixels, the green pixels and the blue pixels. Each OELD includes an anode, a cathode and an emissive material layer. The emissive material layer is disposed between the anode and the cathode.
During the conventional evaporation process of OLED, the part of the pixels not covered by the emissive material layer are covered by a metallic shadow mask while the part of the pixels covered by the emissive material layer are exposed. One opening corresponds to one exposed pixel.
It is therefore an object of the invention to provide a shadow mask and an evaporation system incorporating the same. One opening of the shadow mask corresponds to at least two pixels on the substrate. When an evaporation process is applied to the substrate of the OLED panel through the shadow mask by the evaporation system, the impact on the substrate is largely lessened when the substrate is scratched or pressed by the particles adhered onto the edge of the opening of the shadow mask or when the metallic shadow mask has a bumpy surface. Consequently, the occurrences of dark spots, which arise when the OELD of the pixel is scratched or pressed, are reduced.
The invention achieves the first object by providing a shadow mask including at least one opening. The length of the opening ranges from about 100 μm to about 2000 μm. The width of the opening ranges from about 25 μm to about 75 μm.
The invention further achieves the second object by providing an evaporation system including a chamber, a heater, a retainer and a shadow mask. The heater is disposed in the chamber for heating an evaporation source. The retainer is disposed in the chamber for retaining a to-be-evaporated body. The shadow mask disposed between the heater and the retainer includes at least one opening. The length of the opening ranges from about 100 μm to about 2000 μm. The width of the opening ranges from about 25 μm to about 75 μm.
Other objects, features, and advantages of the invention will become apparent from the following detailed description of the preferred but non-limiting embodiments. The following description is made with reference to the accompanying drawings.
During the conventional evaporation process of OLED, however, particles may be adhered onto the edge of the opening of the shadow mask during the evaporation process of the emissive material layer, and an uneven surface to the metallic shadow mask may occur. If the evaporation process continues to be applied to the substrate disposed on the metallic shadow mask, the metallic shadow mask may scratch or press the substrate. To the worse, the anode and cathode of the OELD of the pixels may be mistakenly activated and cause dark spots to the pixel.
Referring to
The shadow mask 10 is disposed in correspondence to the substrate 11 for the substrate 11 to form an evaporation layer during an evaporation process. Examples of the evaporation layer are emissive material layers of different colors in the OLED panel. The substrate 11 has a pixel array. The pixel array has several columns of pixel groups, such as one column of red pixel group, one column of green pixel group and one column of blue pixel group. The column of red pixel group has eight red pixels R arranged at a constant distance from top to down. The column of green pixel group has eight green pixels G arranged at a constant distance from top to down. The column of blue pixel group has eight blue pixels B arranged at a constant distance from top to down. The openings 12 of the shadow mask 10 correspond to the pixel groups of the same color, and each opening 12 corresponds to at least two but at most twenty pixels of the same color. Each opening 12 of the shadow mask 10 corresponds to two vertically adjacent pixels of the same color of the pixel group in the same column. In the present embodiment of the invention, each opening 12 corresponds to two vertically adjacent blue pixels B of the blue pixel group in the same column such that an evaporation process is applied to form a blue emissive material layer on the blue pixels B. Then, through relative movement between the shadow mask 10 and the substrate 11, that is, the shadow mask 10 is fixed while the substrate 11 is shifted leftwards or the substrate 11 is fixed while the shadow mask 10 is shifted rightwards, each opening 12 corresponds to two vertically adjacent green pixels G of the pixel group in the same column such that an evaporation process is applied to form a green emissive material layer on the green pixels G. Afterward, through relative movement between the shadow mask 10 and the substrate 11, each opening 12 corresponds to two vertically adjacent red pixels R of the pixel group in the same column such that an evaporation process is applied to form a red emissive material layer on the red pixels R.
Any one who is skilled in the technology of the present embodiment of the invention will understand that the technology of the present embodiment of the invention is not limited thereto. For example, the size of each opening 12 is at least larger than the area of two pixels of the same color. Furthermore, the red pixels R, the green pixels G and the blue pixels B respectively have an electrode, such that the red emissive material layer, the green emissive material layer and the blue emissive material layer are correspondingly formed on the electrodes of the red pixels R, the green pixels G and the blue pixels B. Apart from the design of having the opening 12 corresponding to at least two pixels, the opening of the shadow mask 10 may correspond to one pixel only. The design of the opening of the shadow mask 10 is adjusted to fit actual needs.
In the present embodiment of the invention, the opening 12 of the shadow mask 10 corresponds to at least two pixels on the substrate 11, thus reducing the number of the openings 12 of the shadow mask 10. Consequently, when the evaporation process is applied to the substrate 11 of the OLED panel through the shadow mask 10, the openings 12 have fewer edges, largely lessening the impact on the substrate when the particles adhered onto the edges of the openings 12 of the shadow mask 10 scratch or press the substrate 11.
Referring to
The shadow mask 20 corresponds to the substrate 11 for emissive material layers of different colors formed on the substrate 11 during an evaporation process. In the present embodiment of the invention, each opening 12 corresponds to two adjacent blue pixels B while the opening 22 corresponds to four adjacent blue pixels B, such that the evaporation process of forming a blue emissive material layer is applied. Then, through relative movement between the shadow mask 20 and the substrate 11, the evaporation process of forming a green emissive material layer on the green pixels G and the evaporation process of forming a red emissive material layer on the red pixels R are sequentially applied. Any one who is skilled in the technology of the present embodiment of the invention will understand that the technology of the present embodiment of the invention is not limited thereto. For example, the size of the opening 22 is at least larger than the area of four pixels of the same color.
Referring to
The shadow mask 30 corresponds to the substrate 11 for emissive material layers of different colors formed on the substrate 11 during an evaporation process. In the present embodiment of the invention, the opening 12 corresponds to two adjacent blue pixels B, the opening 32 corresponds to six adjacent blue pixels B, such that the evaporation process of forming a blue emissive material layer is applied. Then, through relative movement between the shadow mask 30 and the substrate 11, the evaporation process of forming a green emissive material layer on the green pixels G and the evaporation process of forming a red emissive material layer on the red pixels R are sequentially applied. Any one who is skilled in the technology of the present embodiment of the invention will understand that the technology of the present embodiment of the invention is not limited thereto. For example, the size of the opening 32 is at least larger than the area of six pixels of the same color.
Referring to
The shadow mask 40 corresponds to the substrate 41 for emissive material layers of different colors formed on the substrate 41 during an evaporation process. The substrate 41 has a pixel array. The pixel array has several columns of pixel groups. For example, the pixel array has three columns of red pixel group, three columns of green pixel group and three columns of blue pixel group. Each column of red pixel group has eight red pixels R arranged in a constant distance from top down. Each column of green pixel group has eight green pixels G arranged in a constant distance from top to down. Each column of blue pixel group has eight blue pixels B arranged in a constant distance from top to down. The openings 12 and 22 of the shadow mask 40 correspond to all pixels having the same color. Each opening 12 corresponds to two vertically adjacent blue pixels B of the blue pixel group in the same column, and each opening 22 corresponds to four vertically adjacent blue pixels B of the blue pixel group in the same column, such that the evaporation process of forming a blue emissive material layer on the blue pixels B is applied. Then, through relative movement between the shadow mask 40 and the substrate 41, the evaporation process of forming a green emissive material layer and the evaporation process of forming a red emissive material layer are sequentially applied.
Referring to
The shadow mask 50 corresponds to the substrate 41 for emissive material layers of different colors to be formed on the substrate 41 during an evaporation process. The openings 12 and 22 of the shadow mask 50 correspond to all pixels having the same color. Each opening 12 corresponds to two vertically adjacent blue pixels B of the blue pixel group in the same column, each opening 22 corresponds to four vertically adjacent blue pixels B of the blue pixel group in the same column, such that the evaporation process of forming a blue emissive material layer on the blue pixels B is applied. Then, through relative movement between the shadow mask 50 and the substrate 41, the evaporation process of forming a green emissive material layer on the green pixel G and the evaporation process of forming a red emissive material layer on the red pixels R are respectively applied.
Referring to
The shadow mask 60 corresponds to the substrate 41 for emissive material layers of different colors formed on the substrate 41 during an evaporation process. The openings 12, 22, 32, 62 and 63 of the shadow mask 60 correspond to all pixels having the same color. The opening 12 corresponds to two vertically adjacent blue pixels B of the blue pixel group in the same column. Each opening 22 corresponds to four vertically adjacent blue pixels B of the blue pixel group in the same column. The opening 63 corresponds to three vertically adjacent blue pixels B of the blue pixel group in the same column. The opening 62 corresponds to five vertically adjacent blue pixels B of the blue pixel group in the same column. Thus, the evaporation process of forming a blue emissive material layer on the blue pixels B is applied. Then, through relative movement between the shadow mask 60 and the substrate 41, the evaporation process of forming a green emissive material layer on the green pixels G and the evaporation process of forming a red emissive material layer on the red pixels R are sequentially applied. Any one who is skilled in the technology of the present embodiment of the invention will understand that the technology of the present embodiment of the invention is not limited thereto. For example, the size of the opening 62 is at least larger than the area of five pixels having the same color and the size of the opening 63 is at least larger than the size of three pixels having the same color.
Referring to
Any one who is skilled in the technology of the present embodiment of the invention will understand that the technology of the present embodiment of the invention is not limited thereto. For example, the heater 72 is a heating wire. After a high current flows through the tungsten filament of the heating wire, for example, the heating wire is heated and high temperature is generated for heating the evaporation source 74 into a fluid such as a liquid or a gas first, and then the fluid is evaporated into the chamber 71. If the shadow mask 10 is a magnetic metallic shadow mask, the retainer 73 attracts and retains the shadow mask 10 by magnetism. Therefore, the shadow mask 10 is mounted over the substrate 11 even tightly, such that the gap between the shadow mask 10 and the substrate 11 is substantially avoided, and the organic light emitting material is prevented from being evaporated into an incorrect position on the substrate 11. An organic light emitting material may be evaporated into an incorrect position on the substrate 11, such as the blue organic light emitting material may be evaporated into the adjacent green pixel G when clearance exists between the shadow mask 10 and the substrate 11.
When the evaporation system 70 applies evaporation process to the substrate 11 of the OLED panel via the shadow mask 10, the design that the opening 12 of the shadow mask 10 corresponds to the substrate at least two pixels largely lessens the impact on the substrate when the particles adhered onto the edges of the openings 12 of the shadow mask 10 scratch or press the substrate 11.
Referring to
In the present embodiment of the invention, the formation of the emissive material layer on part of the substrate 11 exposed by the opening 12 is elaborated by the accompanied drawings. Referring to
Firstly, in step 91, as shown in
Afterwards, a continuously distributed electrode is respectively formed on the blue emissive material layer 101, the green emissive material layer 102 and the red emissive material layer 103 such that a number of organic electroluminescence devices (OELD) of the OLED panel are formed on the blue pixels B, the green pixels G and the red pixels R, respectively. One pixel may have only one OELD. The structure of the OELD is like a sandwich with one emissive material layer contained by two electrodes from atop and underneath. Any one who is skilled in the technology of the present embodiment of the invention will understand the design of other structures of the OELD such as the electron transport layer, the electron infusion layer, the hole infusion layer and the hole transport layer, and the technology of other structures of the OELD is not repeated here.
According to the shadow mask and an evaporation system incorporating the same disclosed in the above embodiments of the invention, each opening of the shadow mask corresponds to at least two pixels on the substrate such that the number of openings on the shadow mask is reduced. When the evaporation system applies an evaporation process to the substrate of the OLED panel via the shadow mask, the design that the opening of the shadow mask corresponds to the substrate at least two pixels largely lessens the impact on the substrate when the particles adhered onto the edge of opening of the shadow mask scratches or presses the substrate, hence reducing the occurrences of dark spots which arise when the OELD of the pixels is scratched or pressed.
While the invention has been described by way of example and in terms of a preferred embodiment, it is to be understood that the invention is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.
| Number | Date | Country | Kind |
|---|---|---|---|
| 95117718 | May 2006 | TW | national |
This application is a Divisional Application of co-pending U.S. application Ser. No. 11/527,422 filed Sep. 27, 2006, the subject matter of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11527422 | Sep 2006 | US |
| Child | 12792199 | US |
