JP3672060B2 - Reflective liquid crystal device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reflective liquid crystal device (for example, a combination of electroluminescent elements for auxiliary illumination of a reflective liquid crystal display).
[0002]
[Prior art]
Various displays are now widely used, and these displays have become important information display devices in today's information society, and various display devices suitable for each application have been put into practical use.
[0003]
Among them, the liquid crystal display device is a flat-type passive display, capable of color display and large-scale display, and can be driven at a low voltage to reduce power consumption and at a low price. It has features and is widely used as a display device for television receivers, personal computers, word processors, and the like.
[0004]
Liquid crystal materials are classified into three types based on optical observation: smectic, nematic, and cholesteric. Of these, nematic liquid crystals are widely used in liquid crystal displays. Furthermore, research and development for applying a ferroelectric liquid crystal to a display element has been advanced from the viewpoint of high-speed response and high viewing angle.
[0005]
For example, as shown in FIG. 28, the operation principle of the nematic liquid crystal is that a glass substrate 2a provided with a liquid crystal alignment film 4a and a liquid crystal alignment film 4b are arranged so that liquid crystal molecules are aligned in a uniaxial direction along the substrate surface. A cell gap d is formed between the provided glass substrate 2b and the spacer 5 interposed therebetween, and the liquid crystal molecules are opposed to each other so that the alignment directions thereof are orthogonal to each other. When the liquid crystal 6 is sealed during this period, the alignment direction of the molecules of the liquid crystal 6 is twisted by 90 degrees. When an electric field is applied between the glass substrates 2a and 2b, the twist is released and the alignment of the liquid crystal molecules changes straight in the direction of the electric field. In addition, when a polarizing filter (not shown) is arranged outside the glass substrates 2a and 2b so that the polarization axes are orthogonal, in the transmission method, light is transmitted when no electric field is applied, and light is applied when an electric field is applied. Is shielded.
[0006]
As an electrode for applying an electric field, a plurality of transparent electrodes 3a or 3b such as ITO are formed on each glass substrate 2a and 2b in a stripe shape so that the electrodes of the glass substrates 2a and 2b are orthogonal to each other. When arranged in the simple matrix, a simple matrix is formed in which each intersection part is a pixel. Then, an electrode formed on one glass substrate is driven in a time-sharing manner, and an image is displayed by turning on and off the electrode formed on the other glass substrate in accordance with the image data in accordance with the timing. It can be carried out.
[0007]
In addition, a transparent electrode such as ITO is formed on one glass substrate, and a transparent electrode corresponding to a pixel is combined on the other glass substrate with an active element such as a transistor or a diode for driving the transparent electrode. An active matrix that displays images by forming a plurality and turning each on and off has also been put into practical use. For color display, color filters of three primary colors of red, green, and blue are used.
[0008]
As a liquid crystal display device, a reflection type liquid crystal display device that visually recognizes an image using external light without using a backlight attracts attention particularly for portable information equipment from the viewpoint of low power consumption. However, the visibility of the reflective liquid crystal display device depends on the intensity of external light, and it is extremely difficult to visually recognize information when the external light is weak or in a dark place.
[0009]
Therefore, a normal liquid crystal display device uses a backlight as an illumination method. Conventionally, cold cathode fluorescent lamps, dispersed inorganic electroluminescent panels, and the like have been used as such applications. Although the cold cathode fluorescent lamp is excellent in terms of emission wavelength range, brightness, etc., it needs a reflector and a light guide part to illuminate the entire surface, and it should be improved, such as being bulky and having high power consumption. There is.
[0010]
In addition, the dispersion type inorganic electroluminescent panel has features such as uniform surface light emission and low power consumption, but has insufficient luminance, and is not the three primary colors of red, green and blue even with white light emission. Therefore, it is difficult to apply to a color liquid crystal display device. Furthermore, these illumination systems are AC driven and require a relatively high voltage. Therefore, an inverter circuit is required for driving, and there is a point to be improved that an electric circuit becomes complicated.
[0011]
On the other hand, an organic electroluminescent element (hereinafter sometimes referred to as an organic EL element) is surface emitting, can be driven by a direct current, has high luminance, low power consumption, and a wide wavelength selection range. In addition, since it has a basic characteristic that it is a completely solid-state light emitting element, application to a backlight has been studied.
[0012]
FIG. 29 shows an example of the organic EL element 10 as a light emitting element as described above. The organic EL element 10 includes an ITO (Indium Tin Oxide) transparent electrode 15, a hole transport layer 14, an electron transport layer 12, and a cathode (for example, an aluminum electrode) 11 on a transparent substrate (for example, a glass substrate) 16, for example, by vacuum deposition. Are sequentially formed to a thickness of 1 μm or less.
[0013]
Then, by selectively applying a DC voltage 17 between the transparent electrode 15 as the anode and the cathode 11, holes injected from the transparent electrode 15 were injected from the cathode 11 through the hole transport layer 14. Electrons pass through the electron transport layer 12, and electron-hole recombination occurs at the interface between the two layers. Light emission of a predetermined wavelength is generated from the electron-hole recombination and can be observed from the transparent substrate 16 side.
[0014]
As the light emitting material, for example, a complex compound of aluminum or zinc can be contained, but it may be a layer substantially composed of only an aluminum complex (however, a plurality of types of aluminum complexes can be used in combination), or a zinc complex. It may be a layer composed of only a compound (however, a plurality of types of zinc complexes can be used in combination), or may be a compound obtained by adding a fluorescent substance to these complex compounds. Further, the complex compound and other light emitting substances such as anthracene, naphthalene, phenanthrene, pyrene, chrysene, perylene, butadiene, coumarin, acridine, stilbene, and the like may be used in combination. Such a mixture with a complex compound or a fluorescent substance can be contained in the electron transport layer 12.
[0015]
As a matrix display in which a plurality of such elements are assembled and each has a pixel, a passive matrix type in which parallel electrodes are formed orthogonally or an active element such as a transistor TFT (Thin Film Transistor) is provided for each pixel. There is an active matrix type to be incorporated, and the stripe pattern is arranged for each color of red (R), green (G), and blue (B), and can be configured for full color or multicolor.
[0016]
As an example in which such an organic EL element is applied to a liquid crystal display device, for example, JP-A-4-56923 proposes an example in which an organic electroluminescence element is used for a backlight of a liquid crystal display device. Japanese Laid-Open Patent Publication No. 5-34692 proposes an example in which an organic electroluminescent element composed of a light guide part and a diffuse reflector is used as a light emitting part of a backlight unit for a liquid crystal display.
[0017]
In the above-mentioned Japanese Patent Application Laid-Open No. 4-56923, in a reflection type liquid crystal display device using a reflection plate, the light transmitted through the liquid crystal part is reflected by the reflection layer and passes through the liquid crystal part again to improve the contrast of image display. ing. Therefore, if the distance between the liquid crystal display unit and the reflection plate is too large, the image may be doubled or the contrast may be remarkably deteriorated. However, these points are not considered at all.
[0018]
Further, in Japanese Patent Laid-Open No. 5-34692, the provision of the light guide part which is one of the constituent elements of the present invention causes an increase in the distance between the liquid crystal display part and the reflection plate. Obviously it doesn't fit into the device.
[0019]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and in a reflective liquid crystal device having a light reflecting portion, a reflective liquid crystal device capable of recognizing information in a dark place without impairing the feature of being thin and light. Is intended to provide.
[0020]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above object, the present inventor has found an effective means of auxiliary illumination for the reflective liquid crystal element, and in application to the above-described ordinary liquid crystal display device, in particular, The present inventors have devised measures that can effectively overcome the difficulty of applying an organic EL element to a reflective liquid crystal display device, and have reached the present invention.
[0022]
That is In the present invention, a light-transmitting electroluminescent element including a light emitting layer and a light absorbing layer are laminated in this order on the back surface of a liquid crystal element in which liquid crystal is sealed between a front substrate and a back substrate. Relates to a reflective liquid crystal device provided for auxiliary illumination of the liquid crystal element.
[0024]
Also In the present invention, an electroluminescent element including a light emitting layer is provided for auxiliary illumination of the liquid crystal element on at least a part of the front substrate of a liquid crystal element in which liquid crystal is sealed between a front substrate and a back substrate. The present invention also relates to a reflective liquid crystal device.
[0025]
Here, the “reflection type” means that the entire apparatus is a reflection type and that the liquid crystal element is a reflection type or the electroluminescence element is a reflection type.
[0026]
According to the reflection type liquid crystal device of the present invention, the reflection type liquid crystal display device can be used as a display device even in a dark place where external light is weak or not at all. The field of application can be greatly expanded.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
In the reflective liquid crystal device according to the present invention, it is desirable that an organic electroluminescent element having an electrode on a laminate of organic layers including a light emitting layer is in close contact with and integrated with the back surface of the liquid crystal element.
[0028]
In the above-described apparatus, an organic electroluminescent element having a laminate of organic layers between an electrode that also serves as a light reflector and a counter electrode facing the electrode is in close contact with the liquid crystal element on the counter electrode side. It is desirable.
[0029]
In this case, it is desirable that the thickness of the organic layer laminate is 1 μm or less, and the substrate of the electroluminescent element also serves as the back substrate of the liquid crystal element.
[0030]
Furthermore, the above-described device includes a light-transmissive electroluminescent element and a light. absorption A layer is provided on the back surface of the liquid crystal element, and the liquid crystal element has a plurality of substrates opposed to each other with a predetermined gap therebetween, Polymer dispersion type Liquid crystal is arranged, As an electroluminescent device The organic electroluminescent element is formed by laminating at least a transparent electrode, an organic hole transport layer and / or an organic electron transport layer, an organic light emitting layer, and a metal electrode on an optically transparent substrate. Desirably, a sealing structure is provided. (This is also the case when the electroluminescent element is provided on the front substrate of the liquid crystal element as described later.) . When using an organic electroluminescent element, it is preferable that the entire light emitting portion of the organic electroluminescent element is sealed with a sealing layer made of an ultraviolet curable resin.
[0032]
Further, in the above-described apparatus, when the electroluminescent element is provided on the front substrate side of the liquid crystal element, the light transmissive electroluminescent element corresponds to at least a part of the region of the liquid crystal display unit. For the front substrate It is desirable to be provided on the side opposite to the liquid crystal display unit.
[0033]
In addition, an electroluminescent element is formed in at least a part other than the region of the liquid crystal display unit. For the front substrate The liquid crystal display unit may be provided on the same side, or the electroluminescent element may be provided on the side opposite to the liquid crystal display unit.
[0034]
Furthermore, an electroluminescent element may be provided on at least a part of the side surface of the front substrate.
[0035]
An organic electroluminescent device having a laminate of organic layers including a light emitting layer is formed on a front substrate of a liquid crystal device. body In this case, the substrate of the electroluminescent element is preferably integrated with the front substrate of the liquid crystal element. body You may also serve.
[0036]
【Example】
Examples of the present invention will be described in detail below, but the present invention is of course not limited to the following examples. Note that common reference numerals are used for portions that are common to the conventional example shown in FIGS.
[0037]
FIG. 1 illustrates the present invention. reference 1 is a schematic view of a reflective liquid crystal device according to an example, and an organic EL element 10 is in close contact with a back surface of a reflective liquid crystal element (hereinafter sometimes simply referred to as a liquid crystal element) 19 for auxiliary illumination of the liquid crystal element 19; It is provided integrally. These elements 10 and 19 will be described by the following simple matrix driving method, for example, but can also be driven by an active matrix method.
[0038]
This organic EL element does not necessarily need to be flat in order to improve illumination efficiency and to obtain uniform light emission over the entire panel. However, in order to suppress double display images and suppress deterioration in contrast, it is desirable to make the thickness of the organic laminated film constituting the organic electroluminescent element as thin as possible, preferably 1 μm or less, more preferably 0.5 μm. It is good to be below.
[0039]
FIG. 2 is a sectional view showing further details of the reflective liquid crystal device 20 of FIG. This liquid crystal element 19 is also configured similarly to the conventional example described above with reference to FIG. 28. Specifically, as will be described later, a metal electrode different from the case of FIG. 28 is used for the back side electrode. And between the front panel 2b and the back panel 2a, it is comprised similarly to FIG. 28 except said metal electrode, In FIG. 2, this board | substrate sealing | blocking part is abbreviate | omitted, and the code | symbol 8 is put together. Is shown.
[0040]
As shown in the figure, the organic EL element 10 is configured in the same manner as the conventional example (see FIG. 29), and is further covered with a sealing layer 18 so that the substrate 16 is brought into close contact with the back substrate 2a of the liquid crystal element 19. It has a structure.
[0041]
Thereby, as indicated by an arrow in FIG. 2, the light L emitted from the interface between the hole transport layer 14 and the electron transport layer 12 directly passes through the liquid crystal element 19 and is emitted. ₁ Is reflected on the metal electrode 11 of the organic EL element 10 and reflected light L ₂ To the front substrate of the liquid crystal element 19.
[0042]
Therefore, the substrate 16 needs to be made of an optically transparent material. For example, plastic, glass, ceramic, or other appropriate materials can be used. The thickness of the substrate 16 is preferably as thin as possible so as not to impair the image quality of the display information of the liquid crystal element 19. For this purpose, the substrate 16 is preferably used in close contact with the back surface of the liquid crystal element 19.
[0043]
The transparent electrode 15 on the anode side is made of ITO, SnO. ₂ A light-transmitting conductive material such as can be used. In order to increase the charge injection efficiency, the ITO surface may be treated with an appropriate organic substance or the like.
[0044]
As the hole transport layer 14 and the electron transport layer 12 which are electroluminescent organic thin films, various conventionally known structures can be used as layer structures for obtaining organic electroluminescence. For example, as shown in FIG. 2, in the configuration in which the hole transport layer 14 and the electron transport layer 12 are sequentially laminated on the substrate 16, the material constituting the electron transport layer 12 may have a light-emitting property, or The material constituting the hole transport layer 14 may have a light-emitting property, and both the electron transport layer 12 and the hole transport layer 14 may have a light-emitting property.
[0045]
In addition, when the materials constituting the electron transport layer 12 and the hole transport layer 14 do not have luminescence, at least one or more kinds of luminescent materials are included in either or both of these layers to emit light. Can be made. In these cases, in order to improve luminous efficiency, a thin film for controlling the transport of holes or electrons can be included in the layer structure.
[0046]
Further, as a method other than the above, for example, the hole transport layer 14, the light emitting layer 13 (see FIG. 8), and the electron transport layer 12 may be laminated in order.
[0047]
this Examples of the material of the cathode-side metal electrode 11 that also serves as a light reflection plate of the reflective liquid crystal device 20 include an alloy of an active metal such as Li, Mg, or Ca and a metal such as Ag, Al, or In, or a laminated structure. Can be used.
[0048]
By adopting a structure in which the metal electrode 11, the organic thin films 12 and 14, and the transparent electrode 15 are entirely covered with the sealing layer 18 that seals the laminated body, further effects can be obtained. Any suitable material can be used as long as confidentiality is maintained.
[0049]
in this way, this The reflective liquid crystal device 20 of the example is provided in close contact with the back surface of the liquid crystal element 19 to provide the organic EL element 10 for auxiliary illumination, and the metal electrode 11 of the organic EL element 10 also serves as a light reflecting plate. Therefore, the back substrate 2a of the liquid crystal element 19 and the substrate of the organic EL element 10 may be shared in order to reduce the thickness of the organic EL element 10 as much as possible and increase the effect of auxiliary illumination.
[0050]
3 is a cross-sectional view of a reflective liquid crystal device 20 ′ in which the back substrate 2a ′ of the liquid crystal element 19 ′ and the substrate 16 ′ of the organic EL element 10 ′ are a common substrate (similar to FIG. 2) A part of the elements are omitted and collectively denoted by reference numeral 8). Thereby, the whole is formed thinly and the effect of illumination improves.
[0051]
There are two types of reflective liquid crystal devices, one using a polarizing plate and the other using no polarizing plate. As a non-polarizing plate, there is a method of using light absorption and light transmission due to change in the orientation of the dye using a guest / host liquid crystal in which a dichroic dye and a dichroic dye are added to a nematic phase transition liquid crystal. Since a polarizing plate is unnecessary, high luminance display and low voltage driving are possible, and bright color display is possible in combination with an active element.
[0052]
On the other hand, those using a polarizing plate can provide a higher contrast than the polarizing plate-free type, but have a low brightness. For example, this is an electric field controlled birefringence type, which changes the tilt of the liquid crystal molecules by changing the voltage applied to the liquid crystal, and the resulting change in the birefringence of the liquid crystal layer is detected by a pair of polarizing plates. Therefore, it can be applied to color display. In this case, continuous display of white, black, blue, green, and red is possible without using a color filter in one pixel.
[0053]
FIG. 4 is a perspective view showing a specific configuration of the polarizing plate using type as described above. That is, this Examples and later each Also in the examples, the polarizing plates 9a and 9b are used on both surfaces of the front substrate 2b and the rear substrate 2a as described above depending on the display purpose of the liquid crystal or the liquid crystal element to be used. In FIG. 4, reference numerals 9A and 9B denote polarization axes, and 17A and 17B denote signals or DC power supplies. Note that the illustration of each example is omitted for the polarizing plate.
[0054]
this For example, the organic EL elements 10 and 10 ′ for auxiliary illumination of the reflective liquid crystal device 20 of the example are turned off during bright daytime and turned on in a dark place. The driving method is, for example, a manual type, and the structure of the manual type switch may be various. For example, a system that can be automatically switched using an optical sensor may be employed. The same applies to each example described later.
[0055]
Details of the reflective liquid crystal device configured as described above are shown in FIGS.
[0056]
That is, this The liquid crystal element 19 of the example has, for example, a transparent electrode layer 3a such as ITO (Indium tin oxide: conductive oxide in which tin is doped with indium), and a liquid crystal alignment film on the inner surface of a transparent substrate 2a such as glass. For example, a laminate 1A in which SiO obliquely deposited layers 4a are sequentially laminated to realize a domain having good contrast; similarly, a transparent electrode layer 3b, for example, SiO obliquely deposited layer 4b, is sequentially laminated on the inner surface of the substrate 2b. The laminated body 1B is disposed so that, for example, SiO obliquely deposited layers 4a and 4b, which are liquid crystal alignment films, face each other, and a granular spacer 5 for realizing a predetermined cell gap d is sandwiched between them. A cell is formed, nematic liquid crystal 6 is injected into the cell gap, and the periphery is sealed with an adhesive 7.
[0057]
The organic EL element 10 for auxiliary illumination includes, for example, an ITO (Indium Tin Oxide) transparent electrode 15, a hole transport layer 14, an electron transport layer 12, and a metal electrode (for example, a transparent substrate (for example, a glass substrate) 16). FIG. 5 shows an element in which the aluminum electrode) 11 is sequentially formed by, for example, a vacuum deposition method, and the total thickness of the organic layer is particularly 1 μm or less and is closely attached to the back surface of the liquid crystal element 19. This element is configured for monochromatic use and can be used as an auxiliary light source for surface light emission.
[0058]
Also, this As in the example, when a monochromatic light source is used with the organic EL element 10 as auxiliary illumination, it is not always necessary to provide the organic EL layer over the entire back surface of the liquid crystal element 19, and the organic EL layer is used in a pattern. You can also. When white is used as a light source, it can be achieved by alternately arranging organic EL layers of three primary colors of red (R), green (G), and blue (B) as shown in FIG. This can be achieved by including components that emit red (R), green (G), and blue (B) in the EL layer. In these cases, an appropriate pattern can be selected in consideration of the workability and whitening. The element as shown in FIG. 6 can be applied not only for white light but also for color (for example, multicolor) or for monocolor.
[0059]
Such an organic EL element 10 will be further described with reference to FIGS.
[0060]
FIG. 7 is a schematic plan view of the organic EL element 10A configured as shown in FIG. Thus, the light emitting layer is formed as an independent layer. On the upper surface of the transparent substrate 16, ITO transparent electrodes 15 are formed in a stripe pattern with the same pattern. ₂ The insulating film 21 is formed in a stripe shape with the same pattern. Between the insulating films 21-21, the hole transport layer 14, the light emitting layer 13, the electron transport layer 12, and the aluminum electrode 11 are stacked in substantially the same pattern in this order, and this stacked body is in the same direction as the insulating film 21. Are formed in stripes with the same pattern.
[0061]
FIG. 8 is an enlarged cross-sectional view of part a in the cross section along line AA in FIG. FIG. 9 is an enlarged cross-sectional view of a portion a in the cross section taken along line BB in FIG. The intersections of the upper and lower electrodes 11 and 15 in both figures are individual pixels PX, and a current flows selectively from the transparent electrode 15 on the anode side to the electrode 11 on the cathode side.
[0062]
As above, this In the above example, the organic EL elements 10 and 10 'are provided in close contact with and integrated with the back surfaces of the liquid crystal elements 19 and 19', and the liquid crystal element and the organic EL element are not in close contact with each other. It is different from 4-56923. Further, this is different from the above-mentioned Japanese Patent Laid-Open No. 5-34692 which uses a light guide part and a diffuse reflector.
[0063]
next, this A specific example of the organic EL element 10 described above will be described.
[0064]
<Specific example 1>
For example, CW Tang and SA Van Slyke et al., Applied Physics Letters Vol. 51, No. 12, pp. 913-915 (1987), C. Adachi, S. Tokita, T. Tsutsui, S. Saito et al., Japanese Journal of Applied Physics Vol. 27, No. 2, pages L269-L271 (1988), CW Tang, SA VanSlyke, CH Chen et al., Journal of Applied Physics Vol. 65, No. 9, 3610-3616 Publicly described in the research report published on page (1989), the research report of Applied Physics Letters Vol. 56, No. 9, pages 799-801 (1990), such as C. Adachi, T. Tsutsui, S. Saito, etc. Can be used.
[0065]
The ITO transparent electrode 15 was formed by sputtering. Then, an organic layer film forming method for obtaining green light emission thereon is inserted as a hole transport layer 14 by inserting a vapor deposition mask provided with an opening corresponding to the film forming portion between the glass substrate 16 and the evaporation source. The structural formula of FIG. 11: N, N′-diphenyl-N, N′-bis (3-methylphenyl) 1,1′-biphenyl-4,4′-diamine (hereinafter simply referred to as TPD) is <10 ^-6 The film was deposited to a thickness of 20 nm by a resistance heating method under a Torr vacuum at an evaporation rate of 0.2 to 0.4 nm / s.
[0066]
Further, the structural formula of FIG. 10 serving as an electron transport layer and light emission on this: tris (8-hydroxyquinoline) aluminum (hereinafter simply referred to as Alq) _Three Is vacuum-deposited by resistance heating to a thickness of 40 nm at an evaporation rate of 0.2 to 0.4 nm / s to form an electron transport layer 12.
[0067]
An Mg—Ag (30: 1) alloy was used as the metal electrode 11 of the cathode, and the film thickness was formed to 200 nm. Furthermore, in order to prevent deterioration of the organic EL element 10, Al was vacuum-deposited on the metal electrode 11 with a film thickness of about 200 nm.
[0068]
And the sealing layer 18 which consists of ultraviolet curable resin was adhere | attached on the glass substrate 16 over the whole light emission part, and the whole light emission part was sealed. This operation was performed under a nitrogen atmosphere.
[0069]
The organic EL element 10 manufactured as described above has a voltage of 10 V and a green color of about 500 cd / cm at a current density of 10 mA. ² Was obtained. This was attached in close contact with the front panel of a liquid crystal display unit using a reflective super twist nematic liquid crystal. In this case, the contrast slightly deteriorated, but the display information could be sufficiently visually recognized even in a dark place by turning on the auxiliary illumination.
[0070]
The organic EL element 10 described above can be applied to other reflective liquid crystal displays such as a guest / host liquid crystal in which a dichroic dye is added to a cholesteric / nematic phase transition liquid crystal and a polymer dispersed liquid crystal. It can be applied without drastically changing the configuration.
[0071]
<Specific example 2>
As shown in FIG. 3, the reflection type liquid crystal device 20 ′ in which the substrates 2a ′ and 16 ′ of the liquid crystal element 19 ′ and the organic EL element 10 ′ are in common has the ITO transparent electrode 15 on the back substrate 2a of the liquid crystal element 19 ′. In addition to the formation by sputtering, an organic EL element 10 ′ was formed by the same method as in Example 1. In this example, the contrast slightly deteriorated, but the display information could be sufficiently visually recognized even in a dark place by turning on the auxiliary illumination.
[0072]
<Specific example 3>
When a red or blue light source color is desired, a corresponding light emitting material may be used. There are various methods for obtaining red light emission. For example, Alq which is an electron transporting material _Three A red light emitting dye, for example, the structural formula of FIG. 13: 4-dicyanomethylene-6- (p-dimethylaminostyryl) -2-methyl-4H-pyran (hereinafter simply referred to as DCM), Nile red, perylene This can be realized by including a diimide derivative.
[0073]
There are various methods for obtaining blue light emission. For example, a material emitting blue fluorescence is used as a hole transport material and laminated with an electron transport material. A material emitting blue fluorescence is used as an electron transport material and laminated with a hole transport material. Alternatively, a material that emits blue fluorescence is sandwiched between the hole transport layer 14 and the electron transport layer 12, or a material that emits blue fluorescence is included in the hole transport material or the electron transport material. Is possible.
[0074]
In order to obtain a red light source color, Alq is formed on the hole transport layer 14 (thickness, for example, 50 nm) made of TPD. _Three The electron transport layer 12 containing DCM at a polymerization ratio of 10: 1 was formed to a thickness of, for example, 50 nm. Vacuum deposition is Alq _Three And two evaporation sources to control the evaporation rate of DCM independently. The evaporation rate was controlled by arranging two crystal vibration type film thickness meters so as not to interfere with each other and controlling the power applied to the resistance heating evaporation boat.
[0075]
As the metal electrode 11 on the cathode side, an Al—Li alloy (thickness, for example, 200 nm) was used. In order to prevent the deterioration of the organic EL element 10, Al is vacuum-deposited on the metal electrode 11 with a film thickness of about 200 nm, and then a protective layer 18 made of an ultraviolet curable resin is bonded on the glass substrate over the entire light emitting part. And the whole light emission part was sealed. This operation was performed under a nitrogen atmosphere. The maximum wavelength of light emission when 10 V is applied to the organic EL element 10 is 620 nm, and the light emission intensity is 410 cd / m. ² Met.
[0076]
In order to obtain a blue light source color, the structural formula of FIG. 12: 2- (4-biphenyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (film thickness, for example, 50 nm) The structural formula: 1,1,4,4-tetraphenyl-1,3-butadiene shown in FIG. 14 was vapor-deposited to a thickness of 35 nm, for example. Further on this, Alq _Three A cathode metal electrode 11 made of a layer (thickness, for example, 50 nm) and an Al—Li alloy was formed to a thickness, for example, 200 nm.
[0077]
In order to prevent the deterioration of the organic EL element 10, Al is vacuum-deposited on the metal electrode 11 made of Mg—Ag with a film thickness of about 200 nm, and then the entire light emitting part is sealed on the glass substrate 16 with an ultraviolet curable resin. The stop layer 18 was bonded, and the entire light emitting part was sealed. This operation was performed under a nitrogen atmosphere. When 10 V is applied to the organic EL element 10, the maximum emission wavelength is 470 nm, and the emission intensity is 700 cd / m. ² Met.
[0078]
<Specific Example 4>
When a white light source color is used, the organic EL layers of the three primary colors of red (R), green (G), and blue (B) are alternately arranged as shown in FIG. Can be achieved. In addition, as described in a research report published in Science Vol. 267, pages 1332-1334 of J. Kido, M. Kimura, K. Nagai, etc., red (R), green (G ) And blue (B) can be obtained by including a light emitting component.
[0079]
In order to obtain the three primary colors of red, green, and blue, or to obtain blue light emission, the same method as in the specific example 3 may be used.
[0080]
As above, this The reflective liquid crystal devices 20 and 20A of the example are provided with organic EL elements 10 and 10A for auxiliary illumination as shown in FIGS. 1, 5, and 6 in close contact with the back surfaces of the liquid crystal elements 19 and 19A. Alternatively, as shown in FIG. 3, the back substrate 2 a ′ of the liquid crystal element 19 ′ and the substrate 16 ′ of the organic EL element 10 ′ are common to form a reflective liquid crystal device 20 ′.
[0081]
However, the arrangement of the backlight in the above-mentioned Japanese Patent Laid-Open No. 4-56923 is not in close contact with the back surface of the liquid crystal display unit, and there is no common substrate between the back surface of the liquid crystal display unit and the substrate constituting the organic electroluminescent element. .
[0082]
this According to the example, since the organic EL elements 10 and 10 ′ are provided in close contact with the back surfaces of the liquid crystal elements 19 and 19 ′ for auxiliary illumination of the liquid crystal elements, the organic EL elements 10 and 10 ′ serve as a light source. No light refraction , Acts efficiently as a backlight.
[0083]
In addition, since the metal electrode 11 of the organic EL elements 10 and 10 ′ also serves as a reflector, the light emitted from the organic EL elements 10 and 10 ′ is sufficiently reflected toward the liquid crystal elements 19 and 19A, and the liquid crystal device exits. The amount of incident light can be improved.
[0084]
This realizes a close contact structure between the thin and light reflective liquid crystal elements 19 and 19A and the organic EL elements 10 and 10 '. For example, even when the display of the liquid crystal element depends on external light such as daytime, the organic EL element 10 and 10 'can act as auxiliary illumination, and the display information can be visually recognized by causing the organic EL elements 10 and 10' to emit light in a dark place such as at night.
[0085]
Therefore, it can be used as a display device even in a dark place where the outside light is weak or not at all, which has been a defect of the reflection type liquid crystal display device in the past, and the application field of the reflection type liquid crystal display device is greatly expanded. be able to.
[0086]
FIG. 15 to FIG. First of the present invention 2 shows a reflective liquid crystal device according to the embodiment.
[0087]
FIG. 15 is a schematic view of this embodiment. As shown in FIG. 15, in this embodiment, the transmissive organic EL element 10B is in close contact with the back surface of the reflective liquid crystal element 19B, and the light absorbing layer 24 is provided in close contact. In this structure, the EL element 10B is interposed between the reflective liquid crystal element 19B and the light absorption layer 24.
[0088]
FIG. 16 is a cross-sectional view showing in detail the transmissive organic EL element 10B portion in FIG. That is, the transmissive organic EL element 10B is as described above. reference Unlike the organic EL element 10 of the example, the cathode-side electrode is formed of a thin metal electrode 11A, and an ITO film 25 for maintaining rectifying property adjacent thereto is formed.
[0089]
Thus, by forming the transmissive organic EL element 10B by thinning the metal electrode 11A, the light L generated at the interface between the hole transport layer 14 and the electron transport layer 12 as shown in FIG. The light irradiated to the opposite side of the substrate 16 passes through the metal electrode 11A and is absorbed by the light absorption layer 24.
[0090]
As the liquid crystal material of the liquid crystal element 19B of the reflective liquid crystal element 20B of this embodiment, a polymer dispersed liquid crystal 27 in which liquid crystal grains 28 are dispersed in a polymer is used. FIG. It is the schematic which showed the principle of operation typically.
[0091]
In FIG. 17, the left half a indicates that the voltage is OFF, and the liquid crystal molecules 28 a of the liquid crystal grains 28 are scattered randomly. _Three Is reflected by the liquid crystal molecules 28a and reflected light L ₂ Scattered and part of the light L ₂ 'Passes between the liquid crystal molecules 28a and is absorbed by the light absorption layer 24.
[0092]
On the other hand, the right half b shows a state in which the voltage is ON, and the liquid crystal molecules 28a are aligned by the applied voltage, and the incident light L ₁ It reaches the light absorption layer 24 straight and shows that it is absorbed.
[0093]
Thus, in the polymer dispersion type liquid crystal element 19B, light scattering occurs due to the difference in refractive index between the liquid crystal and the polymer, but the refractive index of the liquid crystal and the polymer can be changed by changing the refractive index of the liquid crystal by voltage application. It takes advantage of being transparent when they are equal.
[0094]
Therefore, this liquid crystal device 20B is provided with a light absorption layer on the back surface, the light scattering portion performs white display, and the light transmission portion absorbs light transmitted through the liquid crystal display portion by the light absorption layer 24 and displays black. It is something to do.
[0095]
As the liquid crystal material of the above device, a nematic liquid crystal to which a dichroic dye is added to form a guest / host liquid crystal can be used. As described above, the transmissive organic EL element 10B is provided between the liquid crystal element 19 and the light absorption layer 24. By using the transmissive organic EL element 10B, the transmissive organic EL element 10B is dark without impairing the features of the thin and light reflective liquid crystal device. The display information can be visually recognized even in places.
[0096]
18 to 20 are Other references of the present invention It is the schematic of reflection type liquid crystal device 20C by an example. FIG. 18 is a schematic view of this, as shown in the figure, this The example is different from the above-described embodiment in that the transmissive organic EL element 10B is adhered to the back surface of the reflective liquid crystal element 19C. , The light reflection layer 26 is provided, and the transmissive organic EL element 10B is interposed in the middle.
[0097]
this Examples of liquid crystal materials include super twist nematic liquid crystal, cholesteric nematic phase transition liquid crystal, guest / host liquid crystal in which dichroic dye is added, and birefringence of super twist nematic liquid crystal phase. An electric field control birefringence method that is controlled by changing the applied voltage can be used.
[0098]
Further, the back electrode of the liquid crystal element 19C needs to be transparent, and by using a light diffusing reflector provided on the back surface through the transmissive organic EL element 10B, the thin and light reflective liquid crystal device is characterized. Display information can be visually recognized even in a dark place without impairing.
[0099]
this The transmissive organic EL element 10B used in the example is a transmissive organic EL element 10B having the same configuration as that of the above embodiment as shown in FIG. And also in this case reference Similarly to the example, as shown in FIG. 20, the back substrate 2a ′ of the liquid crystal element 19C ′ and the substrate 16 ′ of the transmissive organic EL element 10B ′ may be a common substrate.
[0100]
Thereby, the light L emitted at the interface between the hole transport layer 14 and the electron transport layer 12 is directly emitted light L. ₁ And reflected light L reflected by the light reflecting layer 26 and emitted. ₂ And functions as auxiliary illumination for visually recognizing display information of the liquid crystal element 19C.
[0101]
As above, this In the example, the transmissive organic EL elements 10B and 10B ′ are provided in close contact with and integrated with the back surfaces of the liquid crystal elements 19C and 19C ′, and the metal electrode disclosed in Japanese Patent Laid-Open No. 4-56923 has a thickness of 100 to 200 nm. It is fundamentally different from the non-transmission type formed.
[0102]
In addition, the above-mentioned Japanese Patent Laid-Open No. 5-34692 makes the light guide part, the reflection diffusion part, and the light source part as essential constituent requirements. this These are not necessary for the example, and this The transmissive organic EL element of the example is not included in Japanese Patent Laid-Open No. 5-34692, this Is different.
[0103]
Next, the embodiment described above And other reference examples A specific example of the organic EL element will be described.
[0104]
<Specific example 1>
For example, G. Gu, V. Bulovic, PE Burrows, SR Forrest, etc., as a method for producing a transmissive organic EL device, are known as reported in Applied Physics Letters 68, 19: 2606-2608 (1996). Can be used.
[0105]
Above reference A vapor deposition mask provided with an opening corresponding to the film forming portion is inserted between the glass substrate 16 and the evaporation source in the ITO transparent electrode 15 formed on the glass substrate 16 by a method similar to the example, and the hole transport layer 14 TPD: The structural formula of FIG. ^-6 The film was deposited to a thickness of, for example, 20 nm at a evaporation rate of 0.2 to 0.4 nm / s by a resistance heating method under a Torr vacuum.
[0106]
On top of this, Alq combines electron transport and light emission. _Three : The electron transport layer 12 was formed by vacuum deposition of the structural formula of FIG. 10 to a thickness of 40 nm at an evaporation rate of 0.2 to 0.4 nm / s by a resistance heating method.
[0107]
As the cathode metal electrode 11, an Mg—Ag (30: 1) alloy was used, and when the film thickness was increased, light was not transmitted but was completely reflected. Next, the sample was transferred to the rf magnetron sputtering apparatus, and the ITO film 25 was laminated and formed. This base pressure is <5 × 10 ^-8 Torr. The sputtering target is, for example, SnO ₂ 10% by weight, In ₂ O _Three Of 90% by weight was used. This purity is, for example, 99% by weight.
[0108]
At this time, the sample was attached to a water-cooled holding jig provided at a position 15 cm above the target. A mixed gas of argon and oxygen was used for sputtering. This mixing ratio was adjusted to 200 sccm and 0.1 sccm for argon and oxygen by a mass flow controller, respectively. The rf power of sputtering was 5 W at a frequency of 13.56 MHz. The ITO film 25 was formed at a rate of 0.005 nm / s and a thickness of, for example, 40 nm.
[0109]
Then, an ultraviolet curable resin was used to form a film of 10 μm or less on the ITO film 25 and adhered to a glass substrate to form the sealing layer 18 of the transmissive organic EL element 10B.
[0110]
In the test of the transmissive organic EL element 10B produced as described above, an 80 W / cm high-pressure mercury lamp was used as the light source. As a result, when the thickness of the metal electrode 11A made of an Mg—Ag (30: 1) alloy is 10 nm, the light transmittance after forming the ITO electrode 25 is about 70% at a wavelength of 530 nm. When the thickness of the film became 40 nm, the light transmittance was several percent, which was not practically used.
[0111]
As a result, the thickness of the metal electrode 11A is set to 10 nm, and the voltage is 10 V and the current density is about 500 cd / cm at a current density of 10 mA. ² Was obtained. As a result of sandwiching this between the polymer-dispersed liquid crystal display unit shown in FIG. 15 and the black light absorption on the back, the contrast slightly deteriorates, but the display information is sufficiently visible even in the dark by turning on the auxiliary illumination. We were able to.
[0112]
<Specific example 2>
When using a white light source color or when obtaining three primary colors of red (R), green (G), and blue (B) reference You may carry out by the method similar to the specific example 4 of an example.
[0113]
Further, organic EL elements 10B ′ emitting red, green and blue light source colors were alternately produced on the glass substrate 16 as shown in FIG. The substrate 16 can be shared with the rear substrate 2a ′ of the liquid crystal element 19C ′ as shown in FIG. Each of the organic EL elements 10, 10 ′ was produced with a width of 1 mm.
[0114]
In order to obtain red (R), green (G), and blue (B) patterned electric field EL elements, openings having dimensions corresponding to positions where organic EL elements corresponding to the respective light source colors are formed are provided. An evaporation mask was used. Vacuum deposition is 10 ^-6 This was performed by a resistance heating method under a vacuum of about Torr.
[0115]
The evaporation rate of the organic layer was 0.2 to 0.4 nm / s, and when two or more components were evaporated, the entire evaporation rate was adjusted to fall within this range.
[0116]
In order to obtain a green light source color, the hole transport layer 14 is formed on the ITO transparent electrode 15 by depositing TPD: the structural formula of FIG. , Alq _Three : The electron transport layer 12 was formed by forming the structural formula of FIG. The red and blue light source colors are also described above. reference It carried out by the method similar to the specific example 3 in an example.
[0117]
Further, similarly to the specific example 1 described above, a metal electrode 11A made of an Al—Li alloy is formed to a thickness of, for example, 10 nm, and an ITO film 25 is provided thereon by the same method as the specific example 1. An electric field EL element 10B ′ was formed.
[0118]
As a result of the test of the organic EL element 10B ′ produced as described above, the maximum emission wavelength when the applied voltage is 10 V is 620 nm for red, 540 nm for green, and 470 nm for blue, and the emission intensity is 410 cd / m for red. ² The green color is 500 cd / m ² 700 cd / m for blue ² Met. However, since the light emission intensities do not match, the target white light source color was obtained as a result of adjusting the intensity of each light source color using an appropriate voltage distribution circuit.
[0119]
According to this embodiment, since the transmissive organic EL element 10B is provided in close contact with the back surface of the liquid crystal element 19B, the light is not refracted when the organic EL element 10B acts as a light source, and the liquid crystal element 19B. Acts efficiently as a backlight.
[0120]
And Book In the embodiment, since the light absorption layer 24 is provided on the back side of the liquid crystal element 19B through the transmissive organic EL element 10B, the inherent white display and black display of the polymer dispersed liquid crystal element 19B are provided. The function can be further enhanced.
[0121]
Also, reference In the example, since the light reflection layer 26 is provided on the back side of the liquid crystal element 19B through the transmissive organic EL element 10B, the emitted light of the organic EL element 10B is sufficiently reflected toward the liquid crystal element 19B, The amount of light emitted from the reflective liquid crystal device can be improved.
[0122]
Thus, a thin and light reflective liquid crystal device can be realized. For example, even when the liquid crystal element 19B depends on external light, the organic EL element 10B can be used as auxiliary illumination. The organic EL element 10B can be used as a light source.
[0123]
Therefore, this embodiment can be used as a display device even in a dark place where the external light is weak or not at all, which is a drawback of the reflective liquid crystal display device. Can be greatly expanded.
[0124]
FIG. 21 to FIG. Second of the present invention 2 shows a reflective liquid crystal device according to the embodiment.
[0125]
This embodiment differs from the first embodiment in which the organic EL element for auxiliary illumination is provided on the back surface of the liquid crystal element, and the organic EL element is provided on the front surface or side surface of the liquid crystal element for auxiliary illumination. ing. Therefore, the organic EL element functions as auxiliary illumination in the daytime due to outside light and in the dark. FIG. 21 is a schematic diagram of a reflective liquid crystal device 30 showing the basic configuration of the present embodiment.
[0126]
In this embodiment, as shown in the figure, the front panel of the liquid crystal element 35 is shown. 2b Is provided with a transmissive organic EL element 10B for auxiliary illumination at a corresponding position on the opposite side of the liquid crystal display unit 31. If the effect of the auxiliary illumination is obtained, the entire surface of the liquid crystal display unit 31 is organic. The EL element 10B may not be provided.
[0127]
The reflective liquid crystal device 30 according to this embodiment includes the liquid crystal element 35. Previous In this method, the liquid crystal display unit 35 is visually recognized through the organic EL element 10B provided in close contact with the surface substrate 2b. Therefore, the organic EL element used for this must be a transmissive type as shown in FIG.
[0128]
22A and 22B are schematic views of a reflective liquid crystal device 30A showing a modification of FIG. 21, wherein FIG. 22A is a front view and FIG. 22B is a plan view.
[0129]
In the present embodiment, as shown in the drawing, the organic EL element 10 for auxiliary illumination is provided on the same side as the liquid crystal display part 31 of the front panel 2b of the liquid crystal element 35 where the liquid crystal display part 31 is not provided. .
[0130]
The organic EL element 10 in this case is preferably a type in which the metal electrode 11 as shown in FIG. 25 (b) also serves as a reflector, but a transmissive organic EL element as shown in FIG. 25 (a). 10B can also be used.
[0131]
And this apparatus 30A is light L which the organic EL element 10 light-emits. _Four As shown in the drawing, the liquid crystal element 35 is irradiated while being totally reflected in the front panel 2b and the liquid crystal display unit 31.
[0132]
FIG. 23 is a schematic view of a reflective liquid crystal device 30B showing a modification of FIG. 22, wherein FIG. 23 (a) is a front view and FIG. 23 (b) is a plan view.
[0133]
In this embodiment, as shown in the drawing, an organic EL element for auxiliary illumination is provided on a part of the side surface of the front panel 2b opposite to the liquid crystal display section 31 where the liquid crystal display section 31 of the front panel 2b of the liquid crystal element 35 is not provided. 10 is provided.
[0134]
In this case, the organic EL element 10 similar to that shown in FIG. 22 can be used, and similarly, the liquid crystal element 35 is irradiated with total reflection.
[0135]
FIG. 24 is a schematic view of a reflective liquid crystal device 30C showing a modified example of FIG. 22, in which (a) is a front view and (b) is a plan view.
[0136]
In this embodiment, as shown in the figure, an organic EL element 10 for auxiliary illumination is provided on a part of the side surface of the front panel 2b of the liquid crystal element 35.
[0137]
In this case, the organic EL element 10 similar to that shown in FIG. 22 can be used, and similarly, the liquid crystal element 35 is irradiated with total reflection.
[0138]
The liquid crystal element 35 used in the above-described embodiments of FIGS. 21 to 24 is a reflective liquid crystal element. FIG. 26 is a cross-sectional view of the main part, and FIG. 27 is a schematic view schematically showing the main part.
[0139]
As this liquid crystal material, phase transition liquid crystal is used as shown in FIG. 27. Therefore, in a natural state where no voltage is applied, the host liquid crystal 6a having the property that liquid crystal molecules are arranged in a spiral form is added to the guest liquid crystal 6a. As a result, the pigment 6b is mixed.
[0140]
Therefore, when no voltage is applied, the liquid crystal molecules 6a and 6b are spiral as shown on the left side of FIG. _Three Is absorbed by the guest molecule 6b and displayed in black. Then, when a voltage is applied, as shown on the right side of FIG. ₁ Is reflected by the metal electrode 23 made of aluminum and reflected light L ₂ Is emitted and displayed in color.
[0141]
Since such a liquid crystal element effectively uses external light, the polarizing plate (see FIG. 3) as described above is not used. In FIG. 27, reference numeral 32 denotes a drive DM element, 33a and 33b denote double metals, and 36 denotes a protective layer.
[0142]
In each of the above-described devices, a light guide unit made of plastic, glass, or other appropriate material is provided in order to improve illumination efficiency or obtain uniform light emission throughout the panel. Needless to say, it may be provided between the elements. Further, for the purpose of further improving the illumination efficiency, a metal mirror or a light diffusing plate can be used as appropriate, or a light blocking plate for blocking unnecessary light may be used.
[0143]
Also, in the modified examples shown in FIGS. 22, 23, and 24, if the luminous intensity of the auxiliary illumination is sufficient for the purpose of use, the organic EL element 10 (10B, 10B, 10 ′) may be provided. As a result, in preparation for the case where any one of the organic EL elements has expired and cannot be used, a spare organic EL element 10 (10B, 10 ′) can be installed in advance for replacement.
[0144]
As described above, the organic EL elements used in this example are classified into the transmissive organic EL element 10B shown in FIG. 25A and the reflective organic EL element 10 shown in FIG. And as shown in FIG. 20, it can also be set as the structure which provides a reflecting plate separately.
[0145]
Moreover, the material and structure which form an organic EL element may be the same as that mentioned above.
[0146]
As described above, in this embodiment, the organic EL element 10 or the transmissive organic EL element 10B is integrally and closely attached to the front panel 2b of the liquid crystal element 35, and is provided for auxiliary illumination. This is different from 56923 and JP-A-5-34692.
[0147]
Next, a specific example of the organic EL element used in this example will be described.
[0148]
<Specific example 1>
The transmissive organic EL element 35 shown in FIG. 21 (specifically, FIG. 25A) of this example is Other references mentioned above This was performed in the same manner as in Example 1 in the example, and was produced in the same manner except that the thickness of the ITO layer 25 adjacent to the metal electrode 11A was 100 nm.
[0149]
When the transmissive organic EL element 35 produced as described above is attached in close contact with the front panel 2b of the liquid crystal display unit 31 using the reflective super twist nematic liquid crystal, the contrast is slightly deteriorated. By turning on the auxiliary illumination, the display information was sufficiently visible even in a dark place.
[0150]
In the present embodiment, the above-described method is applied to other reflective liquid crystal displays such as a guest-host liquid crystal in which a dichroic dye is added to a cholesteric-nematic phase transition liquid crystal and a polymer-dispersed liquid crystal display. Can be applied without significant changes.
[0151]
<Specific example 2>
In the liquid crystal device 30 shown in FIG. 21, the ITO transparent electrode 15, the hole transport layer 14, and the electron transport are formed in a region corresponding to the liquid crystal display portion 31 of the front panel portion 2 b under the manufacturing conditions according to the above-described specific example 1. When the layer 12 and the metal electrode 11A, the ITO layer 25, and the sealing layer 18 were formed and tested, Reference mentioned above As in the example, the display information was sufficiently visible even in the dark.
[0152]
<Specific example 3>
The organic EL element 35 shown in FIG. reference It was produced in the same manner as in Example 1 in the example. Further, the organic EL element 35 shown in FIG. 23 was produced by the same method as described above.
[0153]
When the organic EL element 35 produced in this way was tested, it was about 50 cd / cm in green (light emission maximum wavelength 540 nm) at a voltage of 10 V and a current density of 10 mA. ² The display information was sufficiently visible even in a dark place by turning on the auxiliary illumination.
[0154]
In the present embodiment, the number of auxiliary illuminations can be increased or decreased for the purpose of adjusting the intensity of the light source in accordance with the purpose of use. When a red or blue light source color is desired, a corresponding light emitting material may be used.
[0155]
In order to obtain red light emission, for example, Alq having the structural formula shown in FIG. _Three This can be realized by including a red light-emitting dye, for example, DCM, Nile red, or a perylene diimide derivative having a structure shown in FIG.
[0156]
In order to obtain blue light emission, for example, a material that emits blue fluorescence is used as a material for the hole transport layer 14 and is laminated with an electron transport material, and a material that emits blue fluorescence is used as a material for the electron transport layer 12. And laminated. Alternatively, a method of sandwiching a material emitting blue fluorescence between the hole transport layer 14 and the electron transport layer 12 and including a material emitting blue fluorescence in the material of the hole transport layer 14 or the material of the electron transport layer 12, etc. Can be realized.
[0157]
<Specific Example 4>
If you want to use a white light source color, if you want to obtain the three primary colors of red, green and blue, or if you want to obtain blue light emission reference It can carry out by the method similar to the specific example 4 in an example.
[0158]
In the organic EL element 10 shown in FIG. 22, red, green, blue as shown in FIG. 6 are provided as auxiliary illumination portions on two opposite sides where the liquid crystal display portion 31 on the same side as the liquid crystal display portion 31 is not provided. The organic EL elements 10 (10B, 10 ′) that emit the light source colors were alternately produced.
[0159]
Each light source is made to have a width of, for example, 1 mm, and in order to obtain a patterned electroluminescent element, an opening having a corresponding size is provided at a position where an organic EL element corresponding to each light source color is formed. Using a vapor deposition mask, 1 This was carried out in the same manner as the specific example 2 in the example.
[0160]
Similarly, in order to obtain a green light source color, a hole transport layer 14 having the structural formula of FIG. 11 is formed on the ITO transparent electrode 15 to a thickness of, for example, 50 nm by a vacuum deposition method, and then Alq. _Three : The organic EL device in which the structural formula of FIG. 10 is formed to a film thickness of, for example, 50 nm to form the electron transport layer 12, and the metal electrode 11 made of an Al—Li alloy is further formed thereon to a film thickness of, for example, 200 nm. 10 (10B, 10 ') was used.
[0161]
To obtain a red light source color and a blue light source color, 1 This was carried out in the same manner as in Example 2 in Example 1, and an Al—Li alloy (thickness: 200 nm) was used for the metal electrode 11. Other than the above, 1 This was produced according to the specific example 2 in the example.
[0162]
As a result of the test of the organic EL element 19 fabricated as described above, the maximum emission wavelength when 10 V is applied is 620 nm for red, 540 nm for green, and 470 nm for blue, and 410 cd / m for emission intensity in red. ² The green color is 500 cd / m ² 700 cd / m for blue ² Met.
[0163]
The liquid crystal that can be used in the display unit 31 of the reflective liquid crystal device in the present embodiment only adds auxiliary illumination to the front panel 2b, and is not particularly limited. The present invention can be applied to any case where the liquid crystal display unit 31 has a light diffusive reflecting film as shown in FIG. 15 or a black light absorption layer as shown in FIG.
[0164]
<Specific Example 5>
As shown in FIG. 24, when the organic EL element 10 is provided as auxiliary illumination on the side surface of the front panel 2b of the liquid crystal element 35, a light guide may be inserted between the front panel 2b and the organic EL element 10. Further, when the organic EL element 10 is directly attached to the side surface of the front panel 2b, the front panel 2b and the side surface may be formed on a slope to increase the mounting area.
[0165]
For the organic EL element 10 (10B, 10 ′) used in this embodiment, the same materials and manufacturing methods as those in the above embodiments can be applied. For example, in order to obtain a green light source color, the light emission intensity at the time of addition of 10 V is 500 cd / m by manufacturing in the same manner as in the specific example 4 described above. ² Got.
[0166]
In order to obtain a red light source color, TPD: a hole transport layer 14 having a structural formula of FIG. _Three : DCM in the structural formula of FIG. 10: The electron transport layer 12 containing the structural formula of FIG. 13 at a concentration of 0.5 mol% was formed to a thickness of 50 nm.
[0167]
The method of vacuum deposition is the first 1 This was carried out in the same manner as in Example 2 in Example 1, and an Al—Li alloy (thickness 200 nm) was used as the metal electrode. As a result, the emission intensity when 10 V is applied is 410 cd / m. ² Met.
[0168]
In this example, in order to obtain a blue light source color, TPD: 1,1,4,4-tetraphenyl-1 is formed on a hole transport layer 14 having a film thickness of, for example, 50 nm having the structural formula of FIG. , 3-Butadiene: The structural formula of FIG. 14 was deposited to a thickness of, for example, 35 nm. Further on this, Alq _Three Layer: The electron transport layer 12 having the structural formula of FIG. 10 was formed (thickness, for example, 50 nm), and the metal electrode 11 made of an Al—Li alloy was formed to a thickness, for example, 200 nm. As a result, the emission intensity when 10 V is applied is 700 cd / m. ² Met.
[0169]
In the present example, it was produced according to the above example except for the above, but it goes without saying that materials and layer configurations other than those described above can be applied.
[0170]
According to this embodiment, since the organic EL elements 10B and 10 are provided in close contact with the front panel 2b of the liquid crystal element 19B, the light does not refract when the organic EL elements 10B and 10 act as a light source, It works efficiently for auxiliary lighting.
[0171]
When the transmissive organic EL element 10B is provided through the front panel 2b so as to face the entire area of the liquid crystal display unit 31, display information can be viewed through the transmissive organic EL element 10B. . Further, when the organic EL elements 10 and 10B are provided on the same side, the opposite side, or the side surface of the part where the liquid crystal display part 31 is not provided, the display information is directly visually recognized from the front panel 2b side. can do.
[0172]
Thus, a thin and light reflective liquid crystal device can be realized, and for example, even when the visual recognition of the liquid crystal element 35 depends on external light, the organic EL elements 10B and 10 can be used as auxiliary illumination. In a dark place, the organic EL elements 10B and 10 can be used as a light source.
[0173]
Therefore, this embodiment can be used as a display device even in a dark place where external light is weak or not at all, which has been a drawback of the reflection type liquid crystal display device in the past, as in the above embodiments. Thus, the field of application of the reflective liquid crystal display device can be greatly expanded.
[0174]
As mentioned above, although the Example of this invention was described, it can change variously based on the technical idea of this invention besides the Example mentioned above.
[0175]
For example, the materials, shapes, etc. of the electrodes of the organic EL elements used for auxiliary illumination in the above-described embodiments may be variously changed. Further, the liquid crystal element and the organic EL element may be detachably adhered and integrated.
[0176]
In the organic EL device described above, the thickness of the organic layer may be variously changed, and in addition to containing the light emitting material in the hole transport layer or the electron transport layer, light is emitted between the hole transport layer and the electron transport layer. The layers may be provided as independent layers.
[0177]
In addition, a combination of a solar battery and a secondary battery may be used as the power source of the above-described organic EL element that is a light source for auxiliary illumination. A light emitting diode may be used as the electroluminescent element.
[0178]
Moreover, the kind of organic EL element used for each Example is not limited to the above-mentioned Example, A combination may be changed and the kind of liquid crystal element is not limited to the above-mentioned Example.
[0179]
In addition, the first mentioned 2 In addition to the embodiment, various modifications can be made with respect to the shape, mounting position, and number of the organic EL elements for auxiliary illumination in the embodiment.
[0180]
The liquid crystal element described above has been described for a display. However, the present invention is not limited to this, and can be applied to a conversion element having an optical-electric conversion function. Further, the liquid crystal device and the organic EL element described above are not limited to the simple matrix driving method, and may be driven by an active matrix driving method and a structure corresponding to these.
[0181]
[Effects of the invention]
As described above, the present invention provides a light emitting layer on the back surface of a liquid crystal element in which liquid crystal is sealed between a front substrate and a back substrate. Light transmission type including Electroluminescent device And the light absorption layer are laminated in this order. The electroluminescent element is provided for auxiliary illumination of the liquid crystal element. Alternatively, an electroluminescent element including a light emitting layer is provided for auxiliary illumination of the liquid crystal element on at least a part of the front substrate of the liquid crystal element in which liquid crystal is sealed between the front substrate and the back substrate of the liquid crystal element. ing So the back of the liquid crystal element Or front There is no space in which air exists between the electroluminescent element and the electroluminescent element, and no light refraction occurs when the electroluminescent element acts as a light source. Auxiliary light source As efficient as Shi It becomes possible to improve the amount of light emitted from the liquid crystal element In addition, the black display is improved by the light absorption layer. .
[0182]
In this way, a thin and light contact structure between the reflective liquid crystal element and the electroluminescent element can be realized for the first time. For example, the electroluminescence element can be used as auxiliary illumination even in the daytime when the visibility of the liquid crystal element depends on outside light, and the display information of the liquid crystal element can be visually recognized by causing the electroluminescence element to emit light in a dark place. Can do.
[Brief description of the drawings]
FIG. 1 of the present invention reference It is the schematic of the reflection type liquid crystal device by an example.
FIG. 2 is a schematic sectional view of the reflective liquid crystal device.
FIG. 3 is a schematic sectional view of another reflective liquid crystal device.
4 is an exploded perspective view of the reflective liquid crystal device of FIG.
5 is a detailed cross-sectional view of the reflective liquid crystal device of FIG.
6 is a detailed cross-sectional view of a reflective liquid crystal device showing another example of FIG. 2; FIG.
FIG. 7 is a schematic plan view of the organic EL element.
8 is an enlarged view of a part a of the AA cross section of FIG. 7. FIG.
FIG. 9 is an enlarged view of a part a of the BB cross section.
FIG. 10 is the structural formula of tris- (8-hydroxyquinoline) aluminum used.
FIG. 11 is the structural formula of N, N′-diphenyl-N, N-bis (3-methylphenyl) -1,1′-biphenyl-4,4′-diamine used.
FIG. 12 is the structural formula of 2- (4-biphenyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole used.
FIG. 13 shows the same 4-dicyanomethylene-6- ( p -Dimethylaminostyryl) -2-methyl-4H-pyran.
FIG. 14 is the structural formula of 1,1,4,4-tetraphenyl-1,3-butadiene used in the same.
FIG. 15 First of the present invention It is the schematic of the reflection type liquid crystal device by the Example.
FIG. 16 is a schematic sectional view of the reflective liquid crystal device.
FIG. 17 is a schematic diagram schematically showing the main part of the reflective liquid crystal device.
FIG. 18 Other references of the present invention It is the schematic of the reflection type liquid crystal device by an example.
FIG. 19 is a schematic sectional view of the reflective liquid crystal device.
FIG. 20 is a schematic cross-sectional view of another reflective liquid crystal device.
FIG. 21 Second of the present invention It is the schematic of the reflection type liquid crystal device by the Example.
22A and 22B are schematic views showing a modification of the reflective liquid crystal device, where FIG. 22A is a front view and FIG. 22B is a plan view.
FIG. 23 is a schematic view showing another modified example, wherein (a) is a front view and (b) is a plan view.
FIG. 24 is a schematic view showing still another modified example, in which (a) is a front view and (b) is a plan view.
FIG. 25 is a schematic cross-sectional view of the reflective liquid crystal device, in which (a) shows a basic configuration example and (b) shows another configuration example.
FIG. 26 , It is sectional drawing of a reflection type liquid crystal element.
FIG. 27 , It is the schematic which shows typically the principal part of a reflection type liquid crystal element.
FIG. 28 is a cross-sectional view of a transmissive liquid crystal element according to a conventional example.
FIG. 29 is a cross-sectional view of the organic EL element.

Claims (19)

  A light-transmitting electroluminescent element including a light emitting layer and a light absorbing layer are laminated in this order on the back surface of the liquid crystal element in which liquid crystal is sealed between a front substrate and a back substrate. A reflection type liquid crystal device provided for auxiliary illumination. The reflective liquid crystal device according to claim 1 , wherein an organic electroluminescent element having an electrode on a laminate of organic layers including a light emitting layer is in close contact with and integrated with a back surface of the liquid crystal element. The organic electroluminescent device having a laminate of the organic layer between the counter electrodes electrodes opposed thereto which also serves as a light reflecting plate, in close contact with the liquid crystal element on the side of the counter electrode, claim 2. A reflective liquid crystal device according to 2. The reflective liquid crystal device according to claim 2 , wherein a thickness of the organic layer stack is 1 μm or less. Substrate of the electroluminescent device also serves as the rear group of the liquid crystal element, reflection-type liquid crystal device according to claim 1. The liquid crystal element is
A plurality of substrates are opposed to each other with a predetermined gap, and a polymer dispersed liquid crystal is disposed in the gap.
An organic electroluminescent element as the electroluminescent element is
On the optically transparent substrate, at least a transparent electrode, an organic hole transport layer and / or an organic electron transport layer, an organic light emitting layer, a metal electrode and a sealing layer are sequentially laminated.
The reflective liquid crystal device according to claim 1 . The reflective liquid crystal device according to claim 2 , wherein in the organic electroluminescent element, the entire light emitting portion is sealed with a sealing layer made of an ultraviolet curable resin.   A reflective liquid crystal device, wherein an electroluminescent element including a light emitting layer is provided for auxiliary illumination of the liquid crystal element in at least a part of the front substrate of a liquid crystal element in which liquid crystal is sealed between a front substrate and a rear substrate. 9. The reflection according to claim 8 , wherein the electroluminescent element of light transmission type is provided on the side opposite to the liquid crystal display unit with respect to the front substrate , corresponding to at least a part of a region of the liquid crystal display unit. LCD device. At least a portion other than the area of the liquid crystal display unit, the light emitting element, wherein are provided to the front substrate on the same side as the liquid crystal display unit, a reflective liquid crystal device according to claim 8. The reflective liquid crystal device according to claim 8 , wherein the electroluminescent element is provided on at least a part other than a region of the liquid crystal display portion on a side opposite to the liquid crystal display portion with respect to the front substrate . The reflective liquid crystal device according to claim 8 , wherein the electroluminescent element is provided on at least a part of a side surface of the front substrate. The organic electroluminescent device having a stack of organic layers including a light emitting layer, in close contact with the front base body are integrated, the reflection type liquid crystal device according to claim 8. The reflective liquid crystal device according to claim 13 , wherein the organic layer stack has a thickness of 1 μm or less. Substrate of the electroluminescent device also serves as the front group member, a reflective liquid crystal device according to claim 8. The reflective liquid crystal device according to claim 8 , wherein the electroluminescent element is a light reflective type or a light transmissive type. The reflective liquid crystal device according to claim 8 , wherein the liquid crystal element is a reflective type. The liquid crystal element is
A plurality of substrates having a liquid crystal alignment film are opposed to each other with a predetermined gap on the liquid crystal alignment film side, and liquid crystal is arranged in the gap,
An organic electroluminescent element as the electroluminescent element is
On the optically transparent substrate, at least a transparent electrode, an organic hole transport layer and / or an organic electron transport layer, an organic light emitting layer, a metal electrode and a sealing layer are sequentially laminated.
The reflective liquid crystal device according to claim 8 . 14. The reflective liquid crystal device according to claim 13 , wherein in the organic electroluminescent element, the entire light emitting portion is sealed with a sealing layer made of an ultraviolet curable resin.

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