Researchers Submit Patent Application, "Method of Manufacturing an Oled Display Device, the Resulting Oled Display Device and a Timepiece Comprising the Same", for Approval
No assignee for this patent application has been made.
News editors obtained the following quote from the background information supplied by the inventors: "The present invention concerns OLED display devices. More specifically, the present invention concerns display devices known as passive matrix organic light emitting diodes or PMOLEDs. In PMOLED display devices, lighting is controlled by means of anodes and cathodes which are disposed in strips perpendicular to each other and powered separately. Although less energy efficient than active matrix light emitting diodes, also known as AMOLEDs, PMOLED display devices are less complex to make than AMOLED display devices and consequently were the first to be mass marketed.
"Compared to other types of display devices such as liquid crystal cells, OLED display devices have very interesting advantages such as a very rapid response time, improved colour rendering, better contrast or even less directive emissivity, thus offering a broader angle of vision. Compared to liquid crystal display devices, another decisive advantage of OLED display devices is that they do not require backlighting. However, one drawback of OLED display devices is their sensitivity to air and moisture.
"Very succinctly summarised, a PMOLED display device includes a base substrate, for example made of glass, on which anodes are structured in parallel strips. These anodes are made of a transparent, electrically conductive material such as indium tin oxide also known as ITO. After the indium tin oxide layer has been deposited on the glass substrate and the anodes have been structured, there is deposited in succession an insulating layer, whose purpose is to separate the line electrodes and column electrodes from each other, and a separation layer whose role is to create a space between the anodes and the cathodes to be deposited. The actual active layers, of which there are three, are then deposited: a hole injection layer, a hole transport layer and an electron transport layer. Finally, a layer of conductive material such as aluminium is deposited, in which the cathodes are structured. The resulting structure is covered with a cover which is bonded onto the edge of the base substrate. A moisture trap may be arranged in the volume left vacant by the cover.
"As mentioned above, OLED display devices have a certain number of very interesting advantages for use, for example, in portable electronic objects, such as wristwatches. However, in the particular field of horology, those skilled in the art have been confronted by a problem, which, to the Applicant's knowledge, has not yet been resolved. This problem is connected to the combined use, in a timepiece, of a digital OLED display device and an analogue display device which conventionally includes a set of hour and minute hands. Indeed, in that case, the OLED display device is on the watch dial and the hour and minute hands move above the OLED display device. The hour and minute hands are carried by a set of concentric arbours which must necessarily pass through the OLED display device. However, since the active layers and the cathode layer of an OLED display device are very sensitive to air and moisture, it is not possible to envisage piercing the OLED display device for the arbours carrying the hour and minute hands to pass therethrough, since this would place the moisture-sensitive layers of the OLED display device in direct contact with the atmosphere."
As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventor's summary information for this patent application: "Consequently, it is an object of the present invention to provide an OLED display device in which a hole may be made for the arbours carrying the hour and minute hands to pass through.
"The present invention therefore concerns a light emitting diode display device, said display device including a substrate covered by a cover which has a plane surface delimited along the external perimeter thereof by an edge, via which the cover is secured to the substrate, the plane surface of the cover being provided with an outgrowth or protuberance which extends in the direction of the substrate, the substrate being provided with a stack of layers, said stack of layers comprising at least the following layers which succeed each other in the following order starting from the substrate:
"at least one anode layer;
"an insulating coating;
"a spacer layer which has a first exclusion area in a first area which is located plumb with the protuberance;
"an active hole injection layer;
"an active hole transport layer;
"an active electron transport layer;
"a cathode which has a second exclusion area in a second area which is located plumb with the protuberance;
"the protuberance of the cover being joined to the layer with which the protuberance is in contact, a hole, whose diameter is smaller than the geometrical dimensions of the protuberance, being made in the protuberance, and said hole also passing through the substrate.
"As a result of these features, the present invention provides an OLED type display device which can be completely traversed by a hole through which, in the preferred example embodiment of the invention, a set of concentric arbours respectively carrying an hour hand and a minute hand are intended to pass. In fact, the protuberance of the cover, in which the hole is made for the hour and minute hand arbours to pass through, is totally sealed against moisture and oxygen, so that the active layers and the cathode layer of the OLED display device according to the invention are not liable to be damaged. To achieve this result, the present invention teaches providing an exclusion area in the spacer layer and in the cathode layer plumb with the protuberance of the cover. In other words, at the location of these exclusion areas, the materials used to deposit the spacer layer and the cathode layer are omitted. Indeed, after performing several tests, it was realised that if the spacer layer and the cathode layer remain at the place where the protuberance of the cover comes into contact with the active layers of the OLED display device, these cathode and spacer layers experience delamination when the hole is made in the protuberance of the cover, which results in the irreversible destruction of the OLED display device. Finally, it was noted that the quality of the bond between the protuberance and the substrate is much higher when the cathode and spacer layers are not present.
"The present invention also concerns a method of manufacturing an OLED display device, said method including the steps consisting in:
"taking a substrate and a cover which has a plane surface delimited along the external periphery thereof by an edge, via which the cover is intended to be secured to the substrate, the plane surface of the cover being provided with a protuberance, which extends in the direction of the substrate;
"depositing in succession on the substrate at least one anode layer and an insulating coating;
"then depositing a spacer layer in which a first exclusion area is arranged in a first area which will be located plumb with the protuberance of the cover once the cover is secured to the substrate;
"depositing an active hole injection layer, an active hole transport layer and an active electron transport layer in that order;
"depositing a cathode layer in which a second exclusion area is arranged in a second area which will be plumb with the protuberance of the cover once the cover is secured to the substrate, and
"joining the cover to the substrate, then making a hole, whose diameter is smaller than the geometrical dimensions of the protuberance, in the protuberance of the cover and in the substrate.
"According to a complementary feature of the method of the invention, the spacer layer, respectively the cathode layer, is deposited in two successive steps by means of a first mask, in which there is arranged a first aperture corresponding to a first portion of the spacer layer, respectively of the cathode layer, to be deposited, said first mask at least partially concealing an area of the substrate so as to form, in the spacer layer, respectively in the cathode layer, an exclusion area, which will be plumb with the protuberance once the cover is secured to the substrate; and by means of a second mask, which has a second aperture corresponding to a second portion of the spacer layer, respectively of the cathode layer, to be deposited, said second mask concealing if necessary the remainder of the area of the substrate, so as to form in the spacer layer, respectively in the cathode layer, the rest of the exclusion area which will be located plumb with the protuberance once the cover is secured to the substrate, the second aperture of the second mask being complementary to the first aperture of the first mask so that the combination of the first aperture and the second aperture corresponds to the desired spacer layer, respectively the cathode layer.
"The present invention also concerns a timepiece comprising a light emitting diode display device in which a hole is made for an hour hand arbour and a minute hand arbour to pass through.
BRIEF DESCRIPTION OF THE DRAWINGS
"Other features and advantages of the present invention will appear more clearly from the following detailed description of one embodiment of an OLED display device according to the invention, this example being given solely by way of non-limiting illustration with reference to the annexed drawing, in which:
"FIG. 1A is a perspective view of a glass substrate on which a conductive indium tin oxide layer and a chromium layer have been deposited in succession.
"FIG. 1B is a similar view to that of FIG. 1A, showing the step of structuring the chromium layer.
"FIG. 1C illustrates the step of structuring the conductive indium tin oxide layer.
"FIG. 1D illustrates the deposition of an insulating layer.
"FIG. 1E illustrates the structuring of the insulating layer so as to delimit the matrix display pixels.
"FIG. 1F illustrates the deposition of the separation layer.
"FIG. 1G illustrates the structuring of the separation layer.
"FIGS. 1H, 1I and 1J respectively illustrate the deposition of the active hole injection, hole transport and electron transport layers.
"FIG. 1K illustrates the deposition of the cathode layer.
"FIG. 2 is a cross-section of an organic light emitting diode display device according to the invention.
"FIG. 3 is a schematic view of a wristwatch fitted with an OLED display device according to the invention.
"FIGS. 4A, 4B and 4C are top views of the first and second masks used for the vapour deposition of the spacer layer and of the cathode layer."
For additional information on this patent application, see: HAMM, Alain. Method of Manufacturing an Oled Display Device, the Resulting Oled Display Device and a Timepiece Comprising the Same. Filed
Keywords for this news article include: Patents, Electronics, Light-emitting Diode.
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