JPS58221828A - Display device - Google Patents

Abstract

PURPOSE:To provide a display device provided with EL illumination having a high luminance and a long life, by sealing a liquid crystal, etc. between an upper substrate and a lower substrate, disposing an EL layer behind the electrode on the surface of the lower substrate, and applying an electric field on the EL layer. CONSTITUTION:A transparent electrode 4 and an oriented film 5 are coated successively on an upper glass substrate 3, and a transparent electrode 7 and an oriented film 8 are coated successively and similarly on a lower glass substrate 6 as well. A thin film EL panel 10 is disposed behind the electrode 7 on the substrate 6. The panel 10 consists of a thin EL film 11 and conductive films 12, 12'. Such display functions as a reflection type in the daytime, etc. The display functions as a transmission type in the night time, etc. as a voltage is supplied to the panel 10 from the films 12, 12' to emit EL light. The panel 10 is disposed with the substrate 6 in the lower part and a liquid crystal 13 in the upper part whereby the moisture resistance of the panel 10 is improved and the life of the layer 11 is extended. Since the light emitted by the panel 10 illuminates directly the liquid crystal without passing through the plate 6, the luminance of the illuminating light is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel structure for lighting a passive display device such as a liquid crystal display device.

Conventionally, backlights for liquid crystal display devices, which are display devices for passive panels, have been actively developed, and in recent years attempts have been made to use EL (electroluminescence) as a promising device. For example, FIG. 1 shows a liquid crystal display device in which an EL panel 2 is arranged behind a liquid crystal cell l. EL panels are excellent as backlights for liquid crystals in that they can form a surface light source. However, when illuminating with EL, the brightness is generally low, so it is desired to improve the brightness, and the life of EL is short, about 5000 hours, so in order to extend the life, it is necessary to improve the airtightness of the EL seal. is needed.

The present invention was made to eliminate the above-mentioned drawbacks of EL lighting, and an object of the present invention is to provide a display device such as a liquid crystal display device that is equipped with EL lighting that is high in brightness and has a long life.

EMBODIMENT OF THE INVENTION Hereinafter, one Example based on this invention will be described in detail using drawings. FIG. 2 is a side sectional view of a liquid crystal display device according to an embodiment of the present invention. The upper glass substrate 3 has a transparent electrode 4 made of indium oxide or the like and an alignment film 5 made of SiO2 or the like.
are sequentially coated by a method such as vapor deposition. Similarly, on the lower glass substrate 6, a transparent electrode 7 made of indium oxide or the like and an alignment film 8 made of SiO2 or the like are sequentially repaired and deposited by a method such as vapor deposition. A thin film EL panel 10 is disposed on the lower glass substrate 6 behind a transparent electrode 7 with an insulating layer 9 interposed therebetween. This thin film EL panel 1O includes a transparent EL thin film 11 such as a ZnS vapor deposited film and the EL.
A transparent conductive film 12, 12' made of indium oxide or the like is connected to the thin film 1 and supplies voltage to the EL thin film 11. 13 is a liquid crystal composition containing a dichroic dye,
14 is a sealing material, and 15 is a reflecting plate. The liquid crystal composition 1B is twisted, so that this display device constitutes a phase change type guest-host liquid crystal display device. Although this phase change type guest-host liquid crystal display device can display without a polarizing plate, a polarizing plate may be attached on top of the upper glass substrate 3 if necessary (for example, when the illumination light is too strong). . The display device shown in FIG. 2 functions as a reflective display device when there is sufficient external light, such as during the daytime. At this time, the EL thin film 11 and conductive films 12 and 12' constituting the EL panel IO are
Since both are transparent bodies, external light passes through the liquid crystal 1B, passes through the EL panel IO, is reflected by the reflector 15, and passes through the EL panel IO and the liquid crystal 13 again. On the other hand, when external light is not available, such as at night, a voltage is supplied from the conductive film 12, 12' to the EL panel 10 to emit EL light, so that the display device functions as a transmissive type. In this case, EL panel 10
The light emitting direction is divided into the liquid crystal 13 side and the reflection plate 15 side, but the light from the reflection plate 15 side is reflected and returns to the EL panel 10.
It passes through and irradiates the liquid crystal 13 to participate in display. Therefore E
The light emitted from the L panel IO is used for display without loss. If we look at the arrangement environment of the EL panel 1O, the glass substrate 6 is located below and the liquid crystal I3, which is a non-aqueous liquid, is located above and wraps around ta=ct, so the humidity resistant environment of the EL panel 1O is improves and therefore ELL
This helps extend the life of i2O. Furthermore, compared to the conventional example shown in FIG. 1, the light emitted from the EL panel 10 can directly illuminate the liquid crystal without passing through the lower glass plate 6, so that the dimming of light between the glass plate and the autumn equinox can be avoided and the light emission can be substantially reduced. This improves the brightness of illumination light. Furthermore, the EL panel 10 is mounted inside the lower glass substrate 6.
The overall size can be made more compact compared to the case where the L panel is provided separately.

In the above embodiment, an example was shown in which an EL panel was incorporated into a phase change type guest-host liquid crystal display device, but the present invention also includes an FEM (field effect type) liquid crystal display device, a DSM (dynamic scattering type) liquid crystal display device, It can also be fully implemented for electrochromic displays and the like.

According to the present invention as described above, it is possible to obtain an EL lighting device with high brightness and long life in a passive display device such as a liquid crystal display device, so that display contents can be easily checked even in a dark place. , and has a long life, so it is practically preferable.

[Brief explanation of drawings]

FIG. 1 is a sectional side view of a conventional liquid crystal display device with an EL lighting device, and FIG. 2 is a sectional side view of a liquid crystal display device with an EL lighting device according to an embodiment of the present invention. In the figure, 3: Upper glass substrate 4: Transparent electrode 5: Alignment film
6: Lower glass substrate 7: Transparent electrode 8:
Alignment film 9: Insulating layer lO: Thin film EL panel 11: EL
Thin film 12.12': Transparent conductive film 13: Liquid crystal composition 14: Sealing material 15: Reflector plate

Claims (1)

[Claims] 1. An upper substrate on which one electrode is formed on the inner surface, a lower substrate on which the other electrode is formed on the inner surface, and an electro-optical device such as a liquid crystal sealed between the upper substrate and the lower substrate. A display device comprising a display layer, an EL (electroluminescence) layer disposed behind an electrode on the lower substrate surface, and an electric field applying means for applying an electric field to the EL layer.