JPS5825268B2 - EL display panel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of an EL display panel, which is an effective technique for an EL display device using a thin film EL element that emits EL (Electro Luminescence) light upon application of an alternating electric field. be.

Conventionally, for AC-operated thin film EL elements, a high electric field (about 106 V/cm) is regularly applied to the light emitting layer to improve dielectric strength, luminous efficiency, stability of operation, etc.
1 to 2.0 wt% Mn (or Cu, Al, Br
ZnS:Mn (or Zn5e:Mn) EL has a three-layer structure in which a semiconductor light emitting layer doped with ZnS, Zn5e, etc.) is sandwiched between dielectric thin films such as Y2O3, TiO2, etc.
Elements have been developed and improvements in various light-emitting characteristics have been confirmed.

This thin 1EL Li element emits high-intensity light upon application of an alternating current electric field of several KHz, and has the characteristics of long life.

It was also discovered that the light emission of this thin film EL element has a hysteresis characteristic in which the luminance of the light emitted by the same applied voltage differs in the process of increasing the applied voltage and in the process of decreasing the voltage from the high voltage side. In the process of increasing the applied voltage to a thin film EL element having hysteresis characteristics, when light, electric field ζ heat, etc. are applied, the thin film EL element
The element is excited to a state of luminescence brightness corresponding to its intensity,
It is known that there is a memory phenomenon in which the luminance remains in a high state even if light, electric field, heat, etc. are removed and the state is returned to its original state.

A thin film EL device application technology that effectively utilizes this memory phenomenon to utilize a thin film EL device as a memory device is currently being researched and developed in the industry.

FIG. 1 shows the basic structure of a Zn:Mn thin film EL device as an example of a thin film EL device.

The structure of a thin film EL element will be explained in detail based on FIG. 1. A transparent electrode 2 such as In2O3, SnO
The first layer consists of l2O3, Si3N4, SiO2, etc.
A dielectric layer 3 is formed in an overlapping manner by sputtering, electron beam evaporation, or the like.

A ZnS light emitting layer 4 is formed on the first dielectric layer 3 by electron beam evaporation of ZnS:Mn sintered pellets.

At this time, the ZnS:Mn sintered pellets used for vapor deposition are pellets in which Mn, which is an active substance, is set at a concentration depending on the purpose.

A second dielectric layer 5 made of the same material as the first dielectric layer 3 is laminated on the Zn8 layer 4, and a transparent electrode 6 on which a back electrode 6 made of AI or the like is formed by vapor deposition. 2 and the back electrode 6 are connected to an AC power source 7.

The thin film EL element is driven.

When an AC voltage is applied between the electrodes 2 and 6, the ZnS light emitting layer 4
The above AC voltage is induced between the dielectric layers 3 and 5 on both sides of the ZnS light emitting layer 4. Therefore, the electric field generated in the ZnS light emitting layer 4 excites electrons into the conduction band and accelerates them to obtain sufficient energy. , directly excites the Mn luminescent center, and emits yellow light when the excited Mn luminescent center returns to the ground state.

That is, when the electrons accelerated by a high electric field excite the electrons of the Mn atoms that have entered the Zn site, which is the luminescent center in the ZnS luminescent layer 4, and fall to the ground state, the electrons emit light in a wide wavelength range with a peak of approximately 5,850 N. Exhibits strong luminescence.

The thin film EL element having the structure described above can be used as a flat thin display device that takes advantage of the space factor to display characters, symbols, still images, moving images, etc. in computer output display terminal equipment and various other display devices that contain characters and figures. It can be used as a means of displaying images, etc.

FIG. 2 shows an example of a conventional thin film EL panel.

This thin film EL panel adopts a matrix electrode structure in which the transparent electrode 2 and the back electrode 6 shown in FIG. The crossing position corresponds to one picture element on the panel when viewed from a plan view.

To explain based on FIG. 2, transparent electrodes 2, a first dielectric layer 3, and a ZnS light emitting layer 4 are arranged in parallel on a glass substrate 1.
are sequentially laminated, and a Si3N4 film 5 is formed on the ZnS light emitting layer 4.
a and the Al2O3 film 5b superimposed on the Si3N4 film 5a.
A second dielectric layer consisting of is laminated in a two-layer structure, and furthermore, a back electrode 6 arranged in parallel in a direction orthogonal to the transparent electrode 2 is provided on the second dielectric layer, and a thin film EL element is formed. It is configured.

In order to seal this thin film EL element, the glass substrate 1 and the peripheral edge of the back glass plate 80 are adhesively fixed to form an envelope.

A thin film EL element is built into the envelope, and an insulating liquid 9 such as silicone oil is sealed therein.

Furthermore, the lead edge portions 10 of the transparent electrode 2 and the back electrode 6 are extended to the outside of the envelope via the joint between the glass panel board 1 and the back glass plate 8, and are connected to a drive control circuit (not shown) and an electrical connection. connected.

When an alternating current voltage is applied through the transparent electrode 2 and the back electrode 6, a light emitting display is performed on a pixel-by-pixel basis from the front surface of the glass substrate 1.

Thin-film EL panels have a lower operating voltage than conventional cathode ray tubes (CRTs), and are superior in weight and strength to plasma display panels (FDPs), which are similar flat display devices. It has many advantages over LCDs, such as a wider operating temperature range and faster response speed.

Furthermore, since it is a pure solid matrix type panel, it has a long operating life, and its address accuracy makes it very effective as an input/output display means for computers and the like.

Conventionally, in display panels such as FDPs, display cells are attached and fixed to a printed circuit board, etc., and circuit boards and other circuit mounting means that configure drive circuits, control circuits, etc. are installed independently of this printed circuit board. A display device was constructed by connecting the display cell, circuit, and operation section.

On the other hand, it is possible to reduce the size and weight of display devices, reduce costs,
Improving reliability is one of the important development issues imposed by the industry, and there has been a strong desire for new technological improvements that can effectively solve these issues for EL display panels.

In view of the above-mentioned current situation, the present invention has been developed by mounting and fixing an EL display panel on one main surface of a double-sided printed circuit board, and mounting a drive circuit, a control circuit, and other circuits on the opposite main surface of the double-sided printed circuit board. The object of the present invention is to provide a new and useful mounting technology for an EL display panel that improves reliability and achieves smaller size, thinner thickness, and lower cost by effectively utilizing both sides of the substrate.

Hereinafter, the present invention will be described in detail according to embodiments with reference to the drawings.

FIG. 3 is a cross-sectional view of a main part of a thin film EL panel with a matwax electrode structure for explaining one embodiment of the present invention.

Transparent electrodes 2 formed into strips as in FIG. 2 are arranged in parallel on a glass substrate 1 made of heat-resistant glass such as Pyrex.
A first dielectric layer 3 and a ZnS light emitting layer 4 are laminated thereon.

Further, on the ZnS light emitting layer 4, a Si3N4 film 5a, an Al2O
A second dielectric layer with a two-layer structure consisting of three films 5b is deposited.

On the Al2O3 film 5b constituting the second dielectric layer, A1203-X films 11 are laminated in multiple stages to prevent light reflection from the back electrode.

The A1203-X film 11 is made of Al2O3 from which oxygen atoms have been removed, and is alumina oxide exhibiting characteristics similar to aluminum.

The A1203-X film 11 was formed by laminating a multilayer film on the A1□03 film 5b by several times of divided vapor deposition.

In this embodiment, this multilayer film has a three-layer structure.

That is, a first layer having a thickness of about 10λ to 50λ is vacuum-deposited on the Al2O3 film 5b at a temperature of 150'C, and after oxygen leaks, the surface is oxidized.

Next, a second layer is vacuum-deposited on the first layer in the same manner, but the film thickness is made thicker than that of the first layer.

Furthermore, a third stage layer is similarly vacuum-deposited on the second stage layer through an oxygen leak process.

An AI metal layer is formed on the Al203-X film 11 consisting of the above multilayer film at a temperature of 150°C or higher to a film thickness of 1000 to 10000λ.
The back electrode 13 is formed by vapor deposition under controlled conditions.

The back electrode 13 is an A layered over the entire area on the A12o3 film 5b.
By etching the 1203-X film 11 and the AI metal layer according to a predetermined pattern shape, they are arranged in parallel strips.

At this time, the A1203-x film 11 is also etched at the same time, but the Al2O3 film 5b remains without being etched.

Due to the interposition of the A1203-x film 11 consisting of a multilayer film, E
The light that has entered the L panel is absorbed by this Al2O3 film 11, and therefore the amount of light reflected from the back electrode 13 is significantly reduced.

Therefore, when observed with the naked eye from the glass substrate 1 side, the back electrode 13 becomes a black background.

The thin film EL element having the above structure is sealed together with an insulating liquid 9 such as silicone oil in an envelope made of a dish-shaped rear glass plate 8 placed on a glass substrate 1.

Further, the ends of the transparent electrode 2 and the back electrode 13 are connected to one end of a REIT electronic 100 made of a phosphor bronze plate, a copper-beryllium alloy plate, etc., and power is supplied through the lead terminal 10.

The lead terminal 10 is bent toward the first circuit board 14 outside the envelope, and the other end is electrically and mechanically connected to the first circuit board 14.

In this embodiment, the REIT electronic 10 uses a film lead wire.

The envelope containing the thin film EL element is elastically supported by the lead terminals 10 in a floating state with respect to the first circuit board 14 at a certain distance.

The connection of the lead terminal 10 is made using a seventh terminal made of a double-sided printed circuit board.
This is done by directly soldering, brazing, etc. to the copper foil or the like deposited on the circuit board 14 of 1.

A background film 15 made of black vinyl or the like is coated on the main surface of the first circuit board 14 on the side where the envelope is installed, and forms a display background color for the thin film EL element.

Further, the background film 15 functions to absorb light transmitted through the gap between the back electrodes 130.

On the other side of the first circuit board 14, integrated circuits such as a diode array, and electronic components 16 such as ICs and LSIs are mounted on the board 14.
D via the component connector 16' mounted on the surface.
I P (Dual Line Packa)
ge ) method or high voltage MO8IC
16", transistor/game) IC, etc. are mounted to constitute a drive circuit for the thin film EL element.

Furthermore, the connection terminals of the electronic components can be inserted through the double-sided printed circuit board and directly connected by soldering or the like from the EL display panel mounting side.

Various electronic components 16 are similarly mounted on a second circuit board 17 arranged parallel to and opposite to the first circuit board 14.
A drive circuit, a control circuit, and other circuits are configured.

Electrical connection between the first circuit board 14 and the second circuit board 17 is performed by mechanically fitting connector terminals 18 and 19 provided on the main surfaces facing each other at the periphery of the board. .

Naturally, the circuit board can also be a multilayer board with two or more layers.

1. Mechanical connection between each circuit board is performed by inserting and fixing mounting screws 20 into screw holes provided at the corners of the board, and each circuit board is integrally connected.

As described above, a thin film EL panel mounted on the circuit board and integrated with the circuit board is constructed.

When using this thin-film EL panel for information processing, a scanning drive circuit, a data drive circuit, and a gate circuit are required, but each drive circuit must be classified separately and mounted on each circuit board. For example, simplification of circuit configuration,
You can measure alignment.

When a voltage is applied to the transparent electrode 2 and the back electrode 13 from the lead terminal 10 via the control circuit, drive circuit, etc., display is performed in pixel units based on the EL total emission of the ZnS light emitting layer 4 from the glass substrate 1.

At this time, external light that has entered the inside of the element from the glass substrate 1 passes through the dielectric layer 5b and the back electrode 13 before reaching the back electrode 13.
Since the light is absorbed by the light-absorbing A120a-x film 11 interposed therebetween, it is not emitted to the outside from the glass substrate 1 as reflected light, and good display quality is maintained.

As explained in detail above, according to the present invention, an EL display panel is mounted on a double-sided printed circuit board, and this double-sided printed circuit board is used as it is as a board for mounting a drive circuit.
The component mounting density of the L display panel is increased, and the space within the panel is effectively utilized, making it possible to make the EL display panel smaller and thinner.

At the same time, it greatly contributes to cost reduction.

Furthermore, since the connection lead terminals extending outside the envelope of the EL display panel are directly connected to the drive circuit or the like on the printed circuit board, the use of multi-core connectors or the like becomes unnecessary, improving reliability.

Further, on the EL element mounting surface of the double-sided substrate on which the EL element is mounted, a portion corresponding to the back area of the EL element is coated with a black background film to provide a light absorption function.

This double-sided board is equipped with many drive circuit components, so
They have miscellaneous colors and patterns, such as printed wiring patterns for connecting each component, color patterns for soldering between components and wiring, and color patterns for identifying the type of wiring.

On the other hand, since the back electrodes of the EL element are formed into strips and arranged in parallel, light passes through the gaps between the arrangements.

The black background film has the function of absorbing this light and preventing the color and pattern of the double-sided substrate from being seen by the viewer through the arrangement gap of the back electrodes, contributing to improvement of display quality.

Although the above embodiment describes a yellow (yellow) color epidural EL panel with a matrix type electrode structure, the present invention is not limited to this, and segment type electrode structures and others can also be used with green, red, etc. Of course, the present invention can also be applied to thin film EL panels such as the above, and can also be applied to multicolor thin film EL panels in which light emitting layers, electrode layers, etc. are formed in multiple stages.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional configuration diagram showing the basic structure of a conventional thin film EL element. FIG. 2 is a cross-sectional configuration diagram of essential parts showing an example of a conventional thin film EL panel. FIG. 3 □ is a cross-sectional configuration diagram of a main part of a thin film EL panel for explaining one embodiment of the present invention.

Claims (1)

[Claims] 1. In an EL display panel in which an EL display element is mounted on the other main surface of a double-sided substrate formed by disposing a plurality of electronic components constituting a drive circuit on one main surface and interconnecting them,
EI characterized in that the EL display element mounting surface of the double-sided substrate is coated with a black background film that absorbs light transmitted through the EL display element, thereby shielding the wiring pattern of the double-sided substrate.
, display panel.