JPS6091385A - Thin film electrochroluminescence display panel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a display panel using a thin film electroluminescent element (hereinafter referred to as a thin film EL element) that exhibits electroluminescence upon application of a changing electric field.

Conventionally, in thin-film BL elements operating on AC, 0.5 to 3 mo1% of Mn or T is used as the luminescent center in order to improve brightness and luminous efficiency and to obtain long-term operation stability.
b? , +SmF3. ZnS added with PrFs etc.

Semiconductor layer such as Zn5e, Y2O3 or Al40s
.

A thin film EL element having a so-called double insulation structure, which is sandwiched from both sides by insulating layers of PbTiOs, EaTi03, 5iaN, etc., has been used.

An example of the basic structure of a conventional double-insulated thin film EL element is shown in the first example.
As shown in the figure.

In Figure 1, 1 is a glass substrate, 2 is In2O3°5
n02 z Transparent electrode on the substrate side made of TTO or metal thin film, etc. 3 is Y2O5, Al20s *Pb deposited thereon by electron beam or sputter deposition method, etc.
Substrate side insulator layer such as Ti()m, BaTiOs, SisNa, etc., 4 is Mn, T deposited on the (7)
bF3. Zn containing luminescent centers such as SmFs and Prys
It is covered with a S semiconductor layer. This semiconductor layer 4 is also manufactured by an electron beam evaporation method, a sputter evaporation method, or the like. 5 is a backside frame layer deposited on the semiconductor J1!4;
The vapor deposition method and materials are the same as those for the insulator layer 3. Reference numeral 6 is a back electrode made of KT or ITO, which is further deposited thereon, and 7 is an AC power source for driving the EL element, which is connected to the transparent electrode 2 and the back electrode 6.

Next, the light emission principle of an EL element will be briefly explained with respect to the element having the structure shown in FIG.

The semiconductor layer 4 is considered to be a simple capacitor before the start of light emission. Therefore, when an AC voltage from the power source 7 is applied between the electrodes 2 and 6, a voltage corresponding to the capacitance of each is applied to the semiconductor layer 4 and the insulator layer 3.5. When the electric field applied to the semiconductor layer 4 becomes sufficiently high (approximately 10°V/cr, or more)
, electrons are excited in the conductor of the semiconductor layer 4. These electrons are accelerated by the electric field and collide with the luminescent center with sufficient energy to collisionally excite the luminescent center. When the electrons in the luminescent center that have risen to an appropriately excited state return to the ground state, light with an energy value unique to the luminescent center is emitted. In reality, the emission spectrum is broadened to some extent due to interaction with the crystal lattice. Since the emission energy of Mn, TbFs, rSmFs, PrFs, etc., which are the emission centers facing forward, is in the visible region, strong emission is observed.

As is clear from the above description, the thin film EL element emits light only in the portion where the pair of electrodes 2 and 6 face each other. Utilizing this property, it is possible to produce a display panel that is made up of a large number of pixels and can display characters and graphics. In other words, the electrodes 2 and 6 are striped electrodes, and the striped electrodes 2 and 6 are perpendicular to each other. An example of a conventional display panel (hereinafter referred to as a matrix panel) is shown in Fig. 2. In Fig. 2, 8 transparent electrodes on the substrate side are formed in stripes, and 9 is a stripe formed perpendicular to the transparent electrodes. This is the back electrode.In principle, it is the second electrode.
A matrix panel is constructed according to the structure shown in the figure, but when such a panel is actually manufactured, it has become clear that it has the following drawbacks. That is, in FIG. 2, since the substrate-side transparent electrode 8 is striped, stepped portions are formed at the edges of the insulating layers 3 and 5, the semiconductor layer 4, and the striped back electrode 9. This step difference is particularly noticeable in the insulator layer 3, and the thickness of the step portion of the insulator layer 30 becomes extremely thin. For this reason, the probability of failure in this stepped portion becomes abnormally high. Therefore, in conventional matrix panels, the breakdown voltage of the matrix panel is significantly lowered by forming the transparent electrodes on the substrate side in a striped shape compared to when the transparent electrodes on the substrate side are flat. Ta.

The present invention aims to solve the problem in a matrix panel using thin-film EL elements that the dielectric breakdown voltage decreases at the stepped portion of the insulating layer caused by the transparent stripe electrode on the substrate side. The present invention is characterized in that transparent stripe electrodes on the substrate side of a matrix panel are embedded in the substrate, and the surface of the substrate is flattened.

The present invention will be explained in detail below with reference to the drawings.

FIG. 3 is a sectional view of a Mar-IJ xbanel to which the present invention is applied. In the figure, 1o is an insulating layer made of Y z Os that was independently produced before the insulating layer 3 was deposited. The insulator layer 10 was produced by the method described below.

・First, use photoresist 1. TO was etched into stripes. This state is shown in FIG. 4(a).

In FIG. 4(A), reference numeral 11 indicates a remaining portion of the resist for leaving an ITO pattern. Next, Y2O3 was deposited on the panel substrate in the state shown in Figure 4 (0) using a vacuum evaporation method to form ITO.
The same film thickness was deposited.

This state is shown in FIG. 4(b). In FIG. 4(b), 12 is an insulating layer made of Y2O3 deposited in the above process. Next, the remaining photoresist was dissolved using a solvent exclusively used for fumetresist to obtain a panel substrate having the cross section shown in FIG. 4(c). A conventional mask 1 is placed on the board.
(The substrate-side insulator layer 3, the semiconductor 7i!4, the back-side insulator layer 5, and the striped back electrode 9 are fabricated by the same process as in the case of fabricating the TS panel, and the matrix has the structure shown in FIG. 3.) IJ Fuchsnell was produced.

Another embodiment of the matrix panel to which the present invention is applied is shown in FIG. In FIG. 5, 13 is a glass substrate with a groove cut therein, and 14 is a substrate-side transparent strip drive electrode made of ITO formed to fill this groove. The grooved glass substrate 13 was fabricated by sputter etching with argon using photoresist for pattern formation.

After etching, while leaving the photoresist, ITO was deposited to a thickness equal to the depth of the groove in the glass substrate 13, and then the photoresist was removed to form a transparent stripe electrode 14 on the substrate side.

In either of the two embodiments described above, there is no stepped portion in the substrate-side insulating layer 3, and therefore there is no extremely thin portion of the insulating layer 3. Therefore, in such a matrix panel, there is no dielectric breakdown at the stepped portion of the insulating layer 3, and a highly reliable matrix panel can be obtained.

In this case, the semiconductor layer 4, the back side insulator R5, and the striped back electrode 9 also have no step difference caused by the transparent stripe electrode 8 on the substrate side, so damage caused by these steps is reduced, and the mark ) The reliability of IJ xbanel is further improved. Furthermore, in the past, it was necessary to increase the thickness of the insulator layer 3 in order to prevent dielectric breakdown of the matrix panel at the step portion of the insulator layer 3, but by applying the structure of the present invention, the thickness of the insulator layer 3 can be increased. It is possible to reduce the film thickness (6J), which has the effect of reducing the operating voltage of the matrix panel and making it easier to use.

Furthermore, the present invention can be applied not only to matrix panels but also to thin film electroluminescent channels in which substrate-side transparent electrodes and back electrodes are formed in arbitrary patterns to bring about the same effects as described above.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a basic double-insulated thin-film EL device, Figure 2 is a cross-sectional view of a conventional matrix panel using thin-film EL elements, and Figures 3 and 5 show the fabrication process of the flannel. This is a cross-sectional view. In the figure, 1...Glass substrate 2...Substrate side transparent electrode 3 made of ITO or the like.
...Substrate side insulator layer 4 made of Y z Os, etc.
... Semiconductor layer 5 such as Zn8 containing a luminescent center such as Mn
...Y! Back side insulator layer 6 such as Os etc.
・・・・・・Back electrode 7 other than AA etc.・・・E
AC power supply for driving the L element 8...Substrate side transparent stripe electrode 9...Back stripe electrode 10...For obtaining a substrate side insulator layer without steps in a matrix panel Insulator layer 13 made of Y2O3 etc. deposited to obtain an insulator layer of the inserted photoresist remaining portion 12 for etching in the form of an insulating strip 10...transparent stripe on the substrate side Glass substrate with grooves cut for electrodes

Claims (1)

[Claims] (1) A matrix addressed display panel using thin film electroluminescent elements, characterized in that stripe electrodes on the substrate side of the panel are embedded in the substrate and the surface of the substrate is flattened. panel.