JPH09218423A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device which has a sure switching function, is easily formable to a larger screen and higher fineness, is capable of embodying a high-grade display under a high duty driving condition, is capable of attaining driving with a lower voltage and lower electric power consumption, is thin and light, has flexibility as well and is low in a manufacturing cost. SOLUTION: A signal light generating layer 19 which emits light of a prescribed wavelength region is composed of two layers of first and second org. films 17, 18. This signal light generating layer 19 is held by row electrodes 16 and light reflective column electrodes 20. A half mirror layer 15 is arranged in front of the column electrodes 16. The signal light in the perpendicular direction generated in the signal generating layer 19 induces resonance by reflecting between the half mirror layer 15 and the column electrodes 20, by which its light quantity is increased. This signal light is made incident on the photoconductive layer 21 of the corresponding address, by which electron-hole pairs are formed. As a result, the two layers of the third and fourth org. films 22, 23 interposed between this photoconductive layer 21 and the predriving electrodes 25 generate display light. Since the light quantity of the signal light is maximized in the perpendicular direction, the exact driving display of the EL display element 13 is made possible. The high-grade display is consequently embodied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly to a thin flat display.

[0002]

2. Description of the Related Art Conventionally, as a display device, a device which performs a simple matrix display by an XY address system is known. Such a display device has a grid-like electrode array composed of scan electrodes and selection electrodes, and has an LED (light emitting diode), EL, which is provided with individual pixels that are switched by the respective electrodes at the intersections of the electrodes. (Electro lu
minescence) element, LCD (liquid crystal display)
Display devices such as are configured. Generally, in these simple matrix type display devices, one screen (frame) is formed by line-sequentially driving the scan electrode side, and further, this one frame is updated at about 50 Hz or more to enable moving image display. . Such a simple matrix type display device has an extremely simple structure, has high productivity, is easy to be upsized, and has a simple driving circuit. A simple matrix method has been realized in the device.

[0003]

However, in a self-luminous element such as an EL array or an LED array, individual pixels are selected in order to obtain a desired average display brightness in high duty ratio driving. It is necessary to increase the maximum instantaneous brightness, and for example, in driving an organic electroluminescence element of 1/100 duty, the maximum instantaneous brightness required for each pixel to obtain a display brightness of 100 cd / m ² is several thousand to 10,000 cd / Since it reaches m ² , there is a problem that the emission life of the organic EL film is shortened. Therefore, in these arrays, the simple matrix drive is driven at about 1/64 duty. A similar problem exists when it is necessary to obtain good contrast in simple matrix driving of LCD. In order to solve such a problem, the state of each pixel needs to be static regardless of the degree of time division, so that each pixel is required to have a memory property or an appropriate hysteresis. As a measure for this, a liquid crystal display using a thin film transistor (TFT) or an active drive represented by an EL element or a display device having a memory property such as a ferroelectric liquid crystal has been realized. However, since these have a complicated wiring structure, there is a problem that wiring resistance between the driving circuit and the pixel electrode becomes high. When the wiring resistance increases in this way, the amount of current supplied to the pixel changes depending on the position of the pixel, that is, the wiring length up to the pixel. Since the brightness of each pixel or the reflectance of light is determined by the amount of current supplied, there is a problem that variations in the amount of current appear as variations in display. In addition, there is a problem in that the number of manufacturing steps is large due to the complicated structure, which results in high cost. Further, in these display devices, the yield is remarkably deteriorated as the number of pixels is increased. Therefore, when manufacturing a large-area display, the cost increase is a big problem. In addition, TF for each pixel electrode
Due to the provision of T and the formation of the auxiliary capacitance on the pixel electrode, the aperture ratio is low, which causes a reduction in luminance. In the TFT substrate, since the film forming temperature of various material films is 250 ° C. or higher, there is a problem that a display device cannot be manufactured using a flexible substrate such as a film substrate. Further, in the manufacture of TFT, the productivity is low because of the large number of photolithography steps.

The problem to be solved by the present invention is to prevent display variation of display light in each pixel, to perform reliable drive display without crosstalk, and to easily achieve a large screen and high definition. , High-quality display under high-duty driving condition, low voltage driving and low power consumption, thin, lightweight and flexible, low manufacturing cost and good productivity. The point is what kind of means should be taken to obtain a display device.

[0005]

According to the first aspect of the present invention,
A signal light generating element that generates a signal light in a predetermined wavelength range and controls the amount of light emitted according to the traveling direction of the signal light, and a photoelectric conversion layer and a photoelectric conversion layer that generate an electric charge according to the signal light. And a display element in which a region corresponding to a region where electric charge is generated is driven and displayed.

According to the first aspect of the present invention, the signal light generating element generates signal light in a predetermined wavelength range and controls the amount of light emitted according to the traveling direction of the signal light. The size of the generated area can be controlled, and a smaller area can be addressed to display the display element with high definition.

According to a second aspect of the present invention, the signal light generating element causes the signal light in the traveling direction in which the emitted light amount is maximum to be incident on the photoconductive layer.

According to the second aspect of the present invention, the signal light of the signal light generating element is set so that the light amount of the signal light in the direction toward the photoelectric conversion layer is set to the maximum. Since the charges are generated in the traveling direction of the signal light, the charges can be efficiently generated, and a display element having high display efficiency can be realized.

According to a third aspect of the present invention, the signal light generating element is provided with a signal light generating layer for generating the signal light by applying a predetermined voltage.

The invention according to claim 4 is characterized in that the signal light generating layer is an organic electric field generating layer.

In the fourth aspect of the invention, since the signal light emitted by the organic electroluminescent layer has no directivity per se, it can be addressed more accurately by controlling the light quantity according to the traveling direction. .

According to a fifth aspect of the present invention, the signal light generating element has a signal light generating layer for generating the signal light in the predetermined wavelength range, and the signal light generating layer is transparent to the signal light. A plurality of first signal electrodes arranged side by side in the first direction on one surface side, and a second direction different from the first direction on the other surface side of the signal light generation layer, A plurality of second signal electrodes which are arranged side by side so as to intersect with the first signal electrodes in a matrix pattern via a signal generating layer;
It is characterized by having.

In the present invention, the signal light is emitted from the signal light generating layer at the predetermined address by selecting a predetermined electrode from among the first signal electrode and the second signal electrode. be able to. This signal light is the first
The signal light in the direction of passing through the signal electrode and emitted to the display element side is set to have the maximum light amount. Therefore, even if the signal light emitted from the predetermined address of the signal light generating element is incident on the predetermined position of the display element corresponding to the predetermined address by line-sequential driving, drive display can be performed without crosstalk.

According to a sixth aspect of the present invention, the signal light generating element causes the signal light to resonate and irradiates the display element with the signal light in a predetermined traveling direction.

In the sixth aspect of the present invention, of the signal light generated by electroluminescence, the signal light in the predetermined direction is resonated, so that the amplitude of the signal light in the predetermined direction can be increased, and the display element can be displayed. It is possible to increase the light amount and the intensity of the signal light incident on the. Therefore, the corresponding portion of the display element can be surely driven and displayed. Since the directivity of the signal light from the signal light generating element can be enhanced, crosstalk can be prevented.

According to a seventh aspect of the present invention, in the signal light generating element, a reflecting member that is reflective to the signal light is provided on one surface side of the signal light generating layer, and the signal light generating layer is provided with a reflecting member. A half mirror is provided on the other surface side.

In the invention according to claim 7, the signal light emitted from the signal light generating layer is resonated by being reflected between the reflecting member and the half mirror, and substantially resonates in the display area of the display element. It has the effect of increasing the amount and intensity of the signal light in the direction perpendicular to. Therefore, the signal light emitted from the predetermined address of the signal light generating element can be reliably incident on the portion of the display element corresponding to the predetermined address without causing crosstalk.

According to an eighth aspect of the invention, the signal light generating element has a pair of electrodes for injecting charges of different polarities into the signal light generating layer, and the reflecting member is one of the pair of electrodes. It is characterized in that it is any one of the electrodes.

According to the eighth aspect of the present invention, by injecting charges having different polarities from the pair of electrodes into the signal light generating layer, it is possible to generate signal light by electroluminescence from the signal light generating layer. Since one electrode of the pair of electrodes corresponds to a reflecting member, the signal light can be reflected by this electrode and the above-mentioned resonance can be caused between the signal light and the half mirror. Therefore, the signal light emitted from the predetermined address of the signal light generating element can be reliably incident on the portion of the display element corresponding to the predetermined address without causing crosstalk.

According to a ninth aspect of the present invention, the signal light generating element has a pair of electrodes for injecting charges of different polarities into the signal light generating layer, and the half mirror is a dielectric material. Is in contact with any one of the electrodes.

According to the ninth aspect of the invention, the signal light emitted from the signal light generating layer is provided by disposing the half mirror made of a dielectric material in contact with the electrode provided on one side of the signal light generating layer. Can be incident on the half mirror through the electrode, and a predetermined proportion of the signal light incident on the half mirror can be reflected toward the electrode provided on the other side. Since the electrode on the other side is made of the reflecting member, the signal light resonates between the half mirror and the reflecting member, and the amount and intensity of the light can be increased. Therefore, it is possible to reliably drive and display the display element portion corresponding to the light emitting portion of the signal light generating element. Since the directivity of the signal light from the signal light generating element can be enhanced, crosstalk can be prevented.

According to a tenth aspect of the present invention, in the signal light generation element, a distance (l) between the signal light and the half mirror and the reflection member is a wavelength (λ) within a predetermined wavelength range of the signal light. On the other hand, it is characterized in that it is set so that l = nλ / 2 (n is a natural number). According to an eleventh aspect of the invention, in the signal light generating element, the thickness of the signal light generating layer is substantially equal to the distance (l) between the half mirror and the reflecting member.

In a tenth aspect of the invention, the distance (l) between the half mirror and the reflecting member is l = nλ / 2 with respect to the wavelength (λ) in the predetermined wavelength range of the signal light.
The feature is that (n is a natural number). The invention according to claim 11 is characterized in that the film thickness of the signal light generating layer is substantially equal to the distance (l) between the half mirror and the reflecting member. In these inventions, the signal light can be caused to resonate by setting the distance (l) between the half mirror and the reflecting member so as to satisfy the above expression.

According to a twelfth aspect of the present invention, the signal light generating element includes a dielectric film having transparency to the signal light and the signal light generating layer arranged in contact with the dielectric film.
The distance between the dielectric film and the signal light generating layer is substantially equal to the distance (l) between the half mirror and the reflecting member.

According to the twelfth aspect of the invention, the distance (l) between the half mirror and the reflecting member satisfies the equation of l = nλ / 2 (n is a natural number) by adjusting the film thickness of the dielectric film. Then, it is possible to cause resonance in the signal light in a predetermined direction (direction perpendicular to the reflecting member and the half mirror).

According to a thirteenth aspect of the present invention, the display element is characterized in that the photoelectric conversion layer for generating charges by the signal light and the liquid crystal are interposed between a pair of electrodes.

In the thirteenth aspect of the present invention, when the signal light emitted from the signal light generating element is incident on the photoconductive layer having a predetermined dress, charges are generated in the photoconductive layer only in the portion where the signal light is incident. It The liquid crystal in the portion corresponding to the photoconductive layer in which the charges are generated in this way is driven to enable display.

According to a fourteenth aspect of the present invention, the display element comprises a pair of electrodes, the photoelectric conversion layer for generating charges by the signal light and the organic electroluminescent layer for emitting the display light. It has a feature.

In the fourteenth aspect of the present invention, the signal light emitted from the signal light generating layer is incident on the photoconductive layer, and the photoconductive layer in the portion where the charge is generated by this injects the charge from the electrode. To enable. Therefore, it is possible to drive the organic electroluminescent layer to generate display light.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, details of a display device according to the present invention will be described based on embodiments shown in the drawings. (Embodiment 1) FIG. 1 is a sectional view showing the outline of a display device according to Embodiment 1 of the present invention, and FIG. 2 is an exploded perspective view of the display device. Reference numeral 11 in the drawing is a display device. This display device 11
Is substantially composed of a signal light generating element 12 and an EL display element 13 as a display element.

The signal light generating element 12 is, as shown in FIGS. 1 and 2, a transparent substrate 14 made of glass or a polymer film having flexibility, which is transparent to signal light.
A half mirror layer 15 made of a dielectric material is provided on the rear surface of the signal light generating element 12 over the entire light emitting region. The half mirror layer 15 has a traveling direction parallel to the normal to the surface of the half mirror layer 15 and is set so that a certain proportion of light of the wavelength λ is transmitted. . Then, on the rear surface of the half mirror layer 15,
A plurality of row electrodes 16 as first signal electrodes are formed in parallel with each other in the row direction as the first direction.
The row electrode 16 functions as an anode electrode, and may be any electrode material that is transparent to signal light and has a predetermined work function, such as ITO or tin oxide. it can. These multiple row electrodes 1
6 and the half-mirror layer 15 (rear surface), a hole-transporting layer formed by mixing polyvinylcarbazole (PVCz), 2,5-bis (1-naphthyl) oxadiazole (BND) and a white light emitting material. And the 1st organic film 17 as a substantial light emitting layer is formed. The second organic film 18 serving as an electron transporting layer made of tris (8-quinolylate) aluminum complex (Alq3) that is transparent to the signal light is bonded onto the first organic film 17 (rear surface). Are stacked on. The first organic film 17 and the second organic film 18 form a signal light generation layer 19, and the signal light generation layer 18 is transparent to signal light.
The structural formulas of Alq3, PVCz, and BND are shown below.

[0032]

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[0033]

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[0034]

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On the second organic film 18 (rear surface),
A plurality of column electrodes 20 as second signal electrodes, which are arranged in parallel in the column direction orthogonal to the row direction as the second direction and intersect the row electrode 16 via the signal light generation layer 19, are provided. Has been formed. The column electrode 20 functions as a cathode electrode, has a physical property that has a lower work function than the anode electrode, and has a property of reflecting signal light.
It is formed of a metal electrode such as n, AlLi, or MgIn-Al. Further, the row electrodes 16 and the column electrodes 20 extend to the edge of the transparent substrate 14 and are connected to a driving IC (not shown). In this way,
A matrix-driven signal light generating element 12 is configured.

In particular, in this embodiment, as shown in FIG. 1, the distance l between the half mirror layer 15 and the column electrode 20 is 1 = nλ / with respect to the wavelength (λ) in the predetermined wavelength range of the signal light.
2 (n is a natural number, preferably 1 to 3). The half mirror layer 15 has a traveling direction substantially parallel to the normal to the surface of the half mirror layer 15 and a certain proportion of the signal light having the wavelength λ is substantially constant.
Through. The signal light reflected by the half mirror layer 15 is repeatedly reflected between the half mirror layer 15 and the column electrode 20, but of these, it travels in a direction other than parallel to the normal direction of the surface of the half mirror layer 15. Light having a direction is attenuated because it is out of phase and cannot be transmitted through the half mirror layer 15, and has a traveling direction substantially parallel to the normal to the surface of the half mirror layer 15. Light having a wavelength of λ is substantially emitted from the half mirror layer 15 and the column electrode 20.
Since the distance 1 between and is set to nλ / 2, it reaches the half mirror layer 15 again with the same phase, and a certain proportion of this can pass through the half mirror layer 15.
As described above, when the reflection is repeated between the half mirror layer 15 and the column electrode 20, it has a traveling direction substantially parallel to the normal direction of the surface of the half mirror layer 15, and substantially Only the signal light of wavelength λ will be transmitted through the half mirror layer 15. Therefore, the half mirror layer 15 can control the amount of transmitted light according to the directivity in the traveling direction of the signal light.

The EL display element 13 has a display area having an area approximately the same as the area over the entire light emitting area of the signal light generating element 12. The EL display element 13 is formed on the front side of the transparent substrate 14. First, on the front surface of the transparent substrate 14, a plurality of rear driving electrodes 21 as cathode electrodes are formed.
Is formed of, for example, transparent ITO. After that, the drive electrodes 21 are arranged and formed so as to face the respective row electrodes 16 and to overlap each other when seen in a plan view.

The transparent substrate 14 and the rear drive electrode 21 are also provided.
A photoconductive layer 22 is formed on the above so as to cover the entire display region. The photoconductive layer 22 is made of a material that absorbs photons to generate conductive carriers. For example, in the present embodiment, the photoconductive layer 22 is formed using amorphous silicon (a-Si). A dope layer 22A formed by doping an n-type impurity (for example, phosphorus) is formed on the surface layer of the photoconductive layer 22. On this doped layer 22A, a third organic film 2 as an electron transport layer made of Alq3, which is the same material as the second organic film 18 described above, is formed.
3 is formed on the entire surface. The doped layer 22A is
It functions to facilitate injection of electrons into the third organic film 23. Then, a fourth organic film 24 as a hole transport layer is formed on the upper surface of the third organic film 23. The fourth organic film 24 is made of PVCz and BND, but each dot portion (the row electrode 16 and the column electrode 20 of the signal light generating element 12).
In the portion (the portion corresponding to the light emitting region) where and overlap with each other through the signal light generating layer 19, R (red), G (green), and B (blue) are formed so as to form a predetermined color arrangement. A luminescent material for emitting light is mixed. In the figure, 24R, 24G, and 24B are R, G, and
The dot portion of the fourth organic film 24 corresponding to B is shown. The fourth organic film 24 may be formed by using PVC.
A method of applying a mixed material of z and BND and then impregnating a light emitting material corresponding to each dot portion, a method of forming an organic film in which the light emitting material is mixed in advance for each color according to a color arrangement, and the like are used. be able to. The third organic film 23 and the fourth organic film 24 thus formed constitute a display light generating layer 25. Further, on the upper surface of the fourth organic film 24, a transparent front drive electrode 26 as an anode electrode made of ITO is formed over the entire display area.

The signal light generating element 12 thus configured
In the above, in the case where a predetermined voltage is applied between the row electrode 16 and the column electrode 20, white light as signal light is emitted from the portion of the first organic film 17 near the interface with the second organic film 18. . At this time, the signal light of the wavelength λ that is vertically incident on the rear surface of the half mirror layer 15 and the front surface of the column electrode 20 is repeatedly reflected between the half mirror layer 15 and the column electrode 20, resonates, and is transmitted. It should be noted that in FIG. 1, a thick arrow b indicates the resonance light that is repeatedly reflected. As a result, only the light traveling in the direction perpendicular to the signal light generating layer 19 is incident on the EL display element 13 due to resonance. Therefore, the signal light generated from a predetermined address of the signal light generating element 12 has a maximum amount of signal light directed to a predetermined dot of the photoconductive layer 22 corresponding to this address, and is obliquely incident on the half mirror layer. Since the signal light is not transmitted, it does not irradiate the photoconductive layer 22 and does not cause the photoconductive layer 22 to generate electron-hole pair charges to the extent that charges can be injected into the display light generation layer 25. Therefore, by adopting a configuration in which the light amount of the signal light is controlled according to the traveling direction of the signal light as in the present embodiment, a display device without crosstalk can be realized.

Next, the operation and operation of the signal light generating element 12 and the EL display element 13 will be described with reference to the energy diagram shown in FIG. First, the operation and operation of the signal light generating element 12 of this embodiment will be described with reference to FIG. This energy diagram shows that the hole transport layer (first organic film 17) joined to the anode (row electrode 16) is PVC.
The effect on the injection barrier of electrons and holes by mixing BND having an electron transporting property from PVCz in z is described.

In FIG. 3, the alternate long and short dash line shows the energy structure peculiar to BND, and the broken line shows the energy structure peculiar to PVCz. In the case of the composite film in which the respective components are mixed in this way, in terms of the transfer of electrons from the electron transport layer side made of Alq3 to the hole transport layer, the respective electrons at the interface between the hole transport layer and the electron transport layer are Considering the affinity, the electron transport layer reflects the physical properties of components having a smaller electron potential. That is, this interface reflects the physical properties of BND, which is a dopant having an electron transporting property rather than PVCz. Therefore, the electrons from the electron transport layer (Alq3) to the hole transport layer (PVCz + BND) can be relatively easily moved by a predetermined electric field because the energy barrier EtoBND is small. In the transfer of holes from the anode (row electrode 16) side to the hole transport layer, in the ionization potential of the hole transport layer at the interface with the anode (row electrode 16), a material having a smaller hole potential is used. Physical properties are reflected. That is, at the interface between the anode and the hole transport layer, P which also functions as a binder
The physical properties of VCz will be reflected. PV as an energy barrier from the anode (row electrode 16) to the hole transport layer
The energy barrier HfromA of Cz is relatively small, and holes can be easily injected into the hole transport layer by applying a predetermined voltage. Here, the hole transport layer (PVCz + BN
In the movement of holes from D) to the electron transport layer (Alq3), the energy barrier HtoAlq3 is the energy barrier EtoB.
Substantially nothing because it is larger than ND. For this reason,
Light emission due to recombination of electrons and holes is generated by the hole transport layer (PVC
It occurs near the interface with the electron transport layer (Alq3) in z + BND). As a result, the electronic physical properties of the entire EL light emitting layer (signal light generating layer 19) have an energy structure shown by diagonal lines in the figure when focusing on the injection barrier at the interface. That is, regarding the injection barrier of carriers, mixing BND reduces the energy barrier from the electron transport layer to the hole transport layer by the energy barrier EtoBND, and thus facilitates the injection of electrons into the hole transport layer. It is believed that In addition, from the anode to the hole transport layer (PVCz
+ BND) hole transfer to the energy barrier Hf
With mA, holes can be easily moved. In such a signal light generating element 12, by using an organic electroluminescence layer that can be efficiently recombined,
The conditions of high-speed response and high-efficiency light can be satisfied. The signal light emitted from the signal light generating element 12 becomes white light under the influence of the white light emitting material.

The hole transport layer (fourth organic film 24) of the EL display element 13 also emits light by the same action as described above, but the electron transport layer of the fourth organic film 24 (third organic film 23).
Of the light generated near the interface with and, the light traveling toward the photoconductive layer 22 side enters the photoconductive layer 22 as return light (indicated by arrow c in FIG. 1). Further, the light traveling toward the front drive electrode 26 side becomes display light that emits light of a predetermined color due to the light emitting material.

The operation of the entire display device 11 will be described below. First, in the signal light generating element 12, when a predetermined voltage is applied between the row electrode 16 and the column electrode 20 selected by line-sequential scanning, the resonance causes the signal light generating layer 19 to be perpendicular to the signal light generating layer 19 due to the resonance as described above. White signal light (indicated by arrow a in FIG. 1) traveling in the direction is irradiated toward the photoconductive layer 22. At this time, the signal light a emitted from a predetermined address of the signal light generation layer 19 does not enter the photoconductive layer 22 and the doped layer 22A in the adjacent dot regions to excite electron-hole pairs. At this time, the signal light generation layer 1
9 and the photoconductive layer 22 are sufficiently close to each other, the signal light can enter the photoconductive layer 22 while maintaining a practically sufficient spatial frequency. The photoconductive layer 22 and the doped layer 22A in the portion where the signal light is incident are, as described above, electron-doped.
A state in which hole pairs are generated and electrons can be injected into the third organic film 22 is obtained. As a result, the voltage applied between the front drive electrode 26 and the rear drive electrode 21 is applied to a predetermined dot portion of the display light generating layer 25 including the third organic film 23 and the fourth organic film 24. The Rukoto. Note that a DC drive voltage, a pulse voltage, an AC voltage, or the like can be used between the drive electrodes. As a result, as described above, due to the light emission of the EL display element 13, display light (arrow d in FIG. 1) colored by various light emitting materials is generated toward the front, and at the same time, toward the rear, a dashed arrow in FIG. Return light indicated by c is generated. This return light c is generated by the photoconductive layer 22 and the doped layer 22.
Since it is incident on A, the photoconductive layer 22 and the doped layer 22A
Are re-excited to generate new electron-hole pairs. In the Schottky junction between the rear driving electrode 21 and the photoconductive layer 22, holes of the electron-hole pairs generated by the incidence of the signal light a are generated by the rear driving electrode 21 and the front driving electrode 2.
The rear driving electrode 21 of the photoconductive layer 22 due to the potential difference between the
Electrons are injected into the photoconductive layer 22 by being accumulated at the interface with and generating an electron tunnel. Therefore, the photoconductive layer 2
2 holds the state where electrons can be injected into the third organic film 23. Therefore, in the state where the drive voltage is continuously applied to the display light generating layer 25, the electric charge is continuously injected into the display light generating layer 25. While in this state, the display light generating layer 25 can continue to be driven for a sufficiently long time for one frame scanning period, so that the row electrode 16 and the column electrode 20 on the signal light generating element 12 side are in the selected state. Even if it is not satisfied, the display light generating layer 25 maintains the light emission. Therefore, the light emission is maintained by the line-sequential scanning until the second scanning. Note that new display light emission can be performed by releasing the voltage applied to the rear drive electrode 21 immediately before the second scan.

In this embodiment, as described above, since the signal light emitted from the predetermined address of the signal light generating element 12 is surely incident on the predetermined dot of the EL display element 25 corresponding to the predetermined address, the cross occurs. Display without talk is possible. Further, since the display light emission is maintained until the next line-sequential scanning, high-quality display can be performed. In addition, the signal light generating element 12 is formed on one transparent substrate 14.
Since the EL display element 13 can be formed, the display device can be thin and lightweight. Further, since each pixel in the conventional organic electroluminescence element must continue to hold light emission for one screen in high duty matrix driving, the initial voltage must be set extremely high, and therefore the EL display element Although the life of itself has been shortened, according to this embodiment, each pixel has a simple structure without using an active drive typified by a TFT or an element having a memory property such as a ferroelectric liquid crystal. A memory property or an appropriate hysteresis is realized by the feedback light, and a high-quality display can be realized under a high duty driving condition. For the same reason, the luminance required for the EL display element 13 can be reduced in order to obtain a desired display luminance, and the EL display element 13 can be expected to have a long life. Further, it is possible to use the low brightness region where the efficiency of the organic EL element is maximized, and as a result, the power consumption of the entire device can be reduced. Furthermore, in this embodiment, since it can be easily formed on one address substrate 14, the productivity is large when the screen size is increased as compared with the TFT and the ferroelectric liquid crystal display or the plasma display. Furthermore, in this embodiment, since there is no reduction in the aperture ratio due to the high definition and miniaturization, which is a concern in the display device using the TFT, in comparison with the TFT drive element in terms of display brightness and efficiency in the miniaturization. Be advantageous. In addition, it can be formed by a consistent vacuum process and does not require a high level clean room as a manufacturing process. Further, the patterning and alignment technique is also very easy as compared with the TFT manufacturing process, and the film forming process can be performed under a relatively low temperature condition. In addition, in this embodiment, the display light generating layer 25 is made of an organic EL material, but an inorganic EL material may of course be used.

In this embodiment, the mixture of PVCz and BND is used as the hole transport material.
In addition, PVCz itself, a mixture of PVCz, BND and triphenyldiamine derivative (TPD), 4,4 ', 4 "-
Materials such as tris (3-methylphenylphenylamino) triphenylamine: MTDATA can be used. The structural formula of MTDATA is shown below.

[0046]

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In this embodiment, in particular, the signal light generating layer 19 of the signal light generating element 12 and the EL display element 1 are used.
The display light generating layer 25 of No. 3 has a junction structure of an organic film made of PVCz and BND and an organic film made of Alq3, whereby high brightness can be obtained. FIG. 4 shows a two-layer organic electroluminescent device made of the same material as this embodiment and a conventional molecular dispersion polymer type (MDP;
y Doped Polymer) is a graph showing the comparison results of the applied power and the luminance of the single-layer organic electroluminescence device of y Doped Polymer).
Here, the light emitting layer of the single-layer organic electroluminescent device is P
VCz, BND, coumarin 6 as a light emitting material,
The organic electroluminescent device having a two-layer structure is made of PVC.
An organic film made of z, BND, and coumarin 6 is joined to an organic film made of Alq3. Further, the thickness of the light emitting layer of the single-layer organic electroluminescent device is set to 1000Å, and the thickness of both the electron transport layer and the hole transport layer is set to 500Å in the organic electroluminescent device having a two-layer structure. From the figure, it can be seen that the organic electroluminescent device having the two-layer structure can obtain about 6 times the brightness for the same input power as compared with the single-layer organic electroluminescent device.

In this embodiment, of the signal light emitted from the signal light generating element 12, the amount of signal light emitted in the normal direction to the surface of the photoconductive layer 22 is set to be maximum. , It is possible to perform a reliable drive display without crosstalk. Further, since the structures of the signal light generating element 12 and the EL display element 13 are easy, the yield is improved,
Therefore, it is possible to easily achieve a large screen and high definition. Furthermore, since the photoconductive layer 22 of the EL display element 13 maintains the charge injection property by the feedback light during one frame scanning, high quality display can be realized under the high duty driving condition. In addition, since the organic film has a two-layer structure,
Low voltage driving and low power consumption can be achieved, and high brightness can be realized. Furthermore, since the signal light generating element 12 and the EL display element 13 are formed by using an organic film, it is possible to achieve a thin and lightweight display device and a flexible display device.

(Second Embodiment) FIG. 5 is a sectional view showing a display device according to the second embodiment. In this embodiment, the half mirror layer 15 and the column electrode 2 are the same as those in the first embodiment.
In order to adjust the distance (l) from 0 to l = nλ / 2 (n is a natural number), for example, silicon nitride (SiN)
The resonance distance adjusting film 27 as a dielectric film is interposed between the half mirror layer 15 and the row electrode 16. In this embodiment, the half mirror layer 15 is previously formed on the rear surface of the transparent substrate 14, and the resonance distance adjusting film 2 is formed on this surface.
By adjusting 7 to a desired thickness to form a film, it is possible to reliably form a microresonator between the column electrode 20 and the half mirror layer 15. Further, by adjusting the film thickness of the resonance distance adjusting film 27, it is possible to design the resonator structure so as to match the wavelength λ of the signal light excited by the signal light generating element 12. It should be noted that other configurations, operations, operations, and effects in this embodiment are substantially the same as those in the above-described first embodiment.

(Third Embodiment) FIG. 6 is a sectional view of a display device according to a third embodiment. In this embodiment, the present invention is applied to a reflective liquid crystal display element. In the figure, 11 is a display device, and this display device 11 includes a signal light generating element 12
And a liquid crystal display element 30.

As shown in FIG. 6, the signal light generating element 12 has a plurality of row electrodes 32 as an electrode group extending in the row direction on the front surface of an optical signal substrate 31 made of glass or a flexible polymer film. They are arranged in parallel. The row electrode 32 functions as a cathode electrode, and may be any electrode material having reflectivity with respect to signal light and having a predetermined work function, for example, MgIn, A
A metal electrode such as 1Li or MgIn-Al can be used. A second organic film 33 made of tris (8-quinolylate) aluminum complex (Alq3) is formed on the plurality of row electrodes 32 and the optical signal substrate 31 (front surface). On the second organic film 33, polyvinylcarbazole (hereinafter referred to as PVCz) and 2,5-bis (1
-Naphthyl) -oxadiazole (hereinafter referred to as BND) and a first organic film 34 made of are laminated so as to be bonded. The second organic film 33 and the first organic film 34 form a signal light generation layer 35 as an organic EL layer. The signal light generation layer 3 is formed on the first organic film 34.
A plurality of column electrodes 36 extending in the column direction intersecting (orthogonal to) the row electrodes 32 via 5 and having a transparency to the signal light.
Are formed. This column electrode 36 is made of, for example, ITO,
It is made of tin oxide and functions as an anode electrode. Further, in order to protect the electrodes 32 and 36 and the signal light generating layer 35 from water and the atmosphere, the signal light generating layer 35 and the column electrode 36.
A protective film 37 having optical transparency is formed so as to cover the. As the protective film 37, for example, a silicon nitride film can be used. When the electrode is made of a material that is easily oxidized, the portion exposed from the protective film 37 may be made of a material that is not easily oxidized.

The signal light generating element 12 configured as described above
In the above, when the electric field is applied between the row electrode 32 and the column electrode 36, the first organic film 3 in the second organic film 33 is
UV light as a signal light (35
0-400 nm) is emitted. Further, the row electrodes 32 and the column electrodes 36 extend to the edge of the optical signal substrate 31,
It is connected to a driving IC (not shown). Further, the half mirror layer 15 is arranged on the upper surface of the protective film 37. Here, the half mirror layer 15 and the row electrode 32
And the distance (l) to and are set to a length that substantially satisfies l = nλ / 2 (n is a natural number, preferably 1 to 3) with respect to the wavelength (λ) of the ultraviolet light that is the signal light. There is. In this way, the matrix-driven signal light generating element 12 is configured. The half mirror layer 15 is used for the liquid crystal display element 3.
It is provided on the rear surface of the rear transparent substrate 38 forming 0, and is bonded so as to be in close contact with the front surface of the protective film 37.

The liquid crystal display element 30 includes the signal light generating element 12
The display area has an area similar to that of the light emitting area. The configuration of the liquid crystal display element 30 will be described below. The liquid crystal display element 30 includes a front transparent substrate 39 and a rear transparent substrate 3 which form a pair.
8, a TN type liquid crystal 41 sealed by a sealing material 40 between these transparent substrates, and a polarizing plate 42 arranged on the front surface of the front transparent substrate 39, and uses a TN cell having optical activity. Is. In the third embodiment, one transparent rear drive electrode 43 made of ITO is provided on the opposite inner surface of the rear transparent substrate 38 over the entire display area or the column electrode 3.
6 is formed in substantially the same shape as the column electrodes 36 so as to face the column electrodes 36. A photoconductive layer 44 is formed on the front surface of the rear drive electrode 43. Further, this photoconductive layer 44
A reflecting plate 45 made of a dielectric material is provided on the entire front surface of the. Further, the post-alignment film 46 is formed so as to cover the reflection plate 45 and the like.

The photoconductive layer 44 is made of a material that absorbs photons to generate conductive carriers. Such a photoconductive layer 4
Examples of 4 include ZnO, amorphous silicon (a-Si), amorphous selenium (a-Se), and Zn.
Inorganic semiconductors such as S and SnOx, charge transfer complexes such as polyvinylcarbazole, organic photocarrier generation layers (perylenes, quinones, phthalocyanines, etc.) and organic carrier transport layers (arylamines, hydrazines, oxazoles, etc.) A material such as an organic composite material in which and are stacked can be used. In such a material, when a photon is absorbed, a conductive carrier is generated and its impedance is rapidly reduced, so that the material becomes electrically conductive. In particular, in the third embodiment, the photoconductive layer 44 uses ZnO having a light absorption characteristic of absorbing only signal light (ultraviolet light). ZnO usually has no absorption in the visible light range.

On the other hand, on the facing inner surface of the front transparent substrate 39,
A color filter layer 47 having a predetermined color arrangement is formed over the entire display area. Further, one front drive electrode 49 made of ITO is formed on the rear surface of the color filter layer 47 via a transparent protective film 48. further,
A pre-alignment film 50 is formed so as to cover the pre-drive electrodes 49. In the liquid crystal display element 30 having such a configuration,
Since the front drive electrode 49 and the rear drive electrode 43 do not require patterning and only need to be formed over the entire display area, the manufacturing cost thereof is lower than that of a conventional display element using a TFT as a switching element. Can be significantly reduced. The liquid crystal display element 30 and the signal light generating element 12 described above are arranged in dots of the signal light generating element 12 (intersection of the row electrodes 32 and the column electrodes 36) with respect to the color arrangement of the color filter layer 47. The arrangement is such that the signal light is incident on the photoconductive layer 44 while maintaining the spatial frequency.

Next, the operation and operation of the display device 11 in this embodiment will be described. In the present embodiment, when signal light, which is ultraviolet light, is generated from the signal light generation layer 35, only the signal light having the wavelength λ that travels perpendicularly to the signal light generation layer 35 is generated in the half mirror layer 15 and the row electrode 32. It is transmitted while being repeatedly reflected between. Therefore, as the signal light that passes through the half mirror layer 15 and goes to the liquid crystal display element 30, only the signal light in a direction substantially perpendicular to the signal light generation layer 35 is incident. That is, the predetermined row electrode 32 and the predetermined column electrode 36 of the signal light generating element 12 are selected, and the signal light emitted from the predetermined address enters the photoconductive layer 44 of the dot portion corresponding to this address. , To generate electron-hole pairs in the photoconductive layer 44 in that portion. In the present embodiment, since the photoconductive layer 44 is made of ZnO, the signal light that is the ultraviolet light is incident, or only the ultraviolet light of the light including the ultraviolet wavelength range is selectively incident, Generate electron-hole pairs.

When an electron-hole pair is generated in a predetermined dot portion of the photoconductive layer 44, the light pattern of the signal light from the signal light generating element 12 changes the electron-hole pair (conduction The carrier has been converted into a density pattern. The generation amount of electron-hole pairs depends on the intensity of light incident on the photoconductive layer 44, time, and wavelength range. here,
Consider a case where an AC drive voltage is applied between the front drive electrode 49 and the rear drive electrode 43. At this time, the conduction carriers move / reciprocate in the vertical direction (thickness direction) in the photoconductive layer 44 under the influence of the driving electric field. The photoconductive layer 44
Since there is no external electric field in the surface direction (parallel to the rear drive electrode 43), the conduction carriers do not move in that direction. Therefore, only the dot portion irradiated with the signal light has a low electric resistance. Then, the impedance of the photoconductive layer 44 decreases, and the partial pressure with respect to the impedance of the liquid crystal 41 increases. That is, the electric field strength received by the liquid crystal 41 is modulated by reflecting the density pattern of the conductive carriers. Therefore, the liquid crystal 41 is oriented in a predetermined direction, and accordingly, external light as display light enters the liquid crystal cell and is reflected by the reflection plate 45, thereby enabling liquid crystal display. At this time,
The display light is dispersed by passing through the color filter layer 47 to enable color display. The front drive electrode 4
It is possible to drive the liquid crystal 41 even when a DC drive voltage is applied between the drive electrode 9 and the rear drive electrode 43.

In the third embodiment described above, multicolor display can be performed by using color filters, and the twisted nematic (TN) liquid crystal mode is used as the mode of the liquid crystal display element 30, but in addition to this, the super twist Nematic (STN) liquid crystal mode Ferroelectric liquid crystal (FCL) mode, antiferroelectric liquid crystal (AFLC) mode, polymer dispersed liquid crystal (PDLC) mode, phase transition (PC) mode and the like can be applied. In this case, a polarizing plate, an alignment film, and the like may be set according to each liquid crystal mode. For example, in the PDLC liquid crystal mode, it is not necessary to dispose a polarizing plate and an alignment-treated alignment film is not necessary. Further, although the color filter is used in the present embodiment, an ECB mode liquid crystal display element may be used in order to improve the light transmission efficiency. The orientation in this case is not limited to twisted nematic,
Homogeneous, homeotropic, hybrid orientation and the like may be used. In addition to this, TN using optical rotation
It can be applied to liquid crystal display devices such as a liquid crystal mode, an STN liquid crystal mode using birefringence, and a dichroic guest-host (GN) liquid crystal mode. Further, it goes without saying that the present invention can be applied to a liquid crystal display element using a linearly polarizing polarization axis and a multicolor liquid crystal display element having an elliptically polarizing retardation plate.

Although the respective embodiments of the present invention have been described above, the present invention is not limited to them.
Various design changes accompanying the gist of the configuration are possible. For example, in each of the above-described embodiments, the electrode in the signal light generating element 12 is a reflecting member, but the rear electrode may be formed of a transparent material, and a reflecting plate made of a dielectric may be separately arranged behind the electrode. Of course good. Further, in the above-described first and second embodiments, an inorganic EL material can be used for the signal light generation layer and the display light generation layer, in addition to the organic EL material, and the display light generation that constitutes the EL display element 13 is generated. The light emitting material contained in the layer 25 can be appropriately selected according to the display purpose. Further, in the above-described Embodiments 1 to 3, the photoconductive layer is formed of amorphous silicon or ZnO, but in the present invention, each of various photoconductive materials including these or a plurality of materials among them are used. Of course, a material for adjusting the electrical resistivity when the photoconductive layer obtains electrical conductivity, such as a photoconductive perylene pigment or a naphthalene derivative, may be mixed in the photoconductive layer. Other materials for the photoconductive layer include amorphous selenium (a-Se), ZnS, and SnO.
An inorganic semiconductor such as x, a charge transfer complex such as polyvinylcarbazole, an organic photocarrier generation layer (perylenes, quinones, phthalocyanines, etc.) and an organic carrier transport layer (arylamines, hydrazines, oxazoles, etc.) Materials such as laminated organic composite materials can be used. It is needless to say that such a material, when absorbing photons in a specific wavelength range, forms a conductive carrier and its impedance sharply decreases, and thus has charge transporting property and electrical conductivity. Further, although an inorganic EL layer can be used as the signal light generating layer or the display light generating layer, the organic EL layer can be formed thinner in terms of film thickness, and addressing can be performed while maintaining the spatial frequency.
Note that the injection of charges from the photoconductive layer is not only retained by the feedback light, but also by the Schottky junction between the photoconductive layer and the post-driving electrode, tunneling by holes near the interface between the photoconductive layer and the post-driving electrode is performed. Due to the effect, electrons can be injected from the rear driving electrode into the display light generating layer through the photoconductive layer.
With this configuration, the amount of display light can be increased or held even after the signal light is lost.

[0060]

As is apparent from the above description, according to the present invention, the directivity of the signal light incident on the photoconductive layer can be controlled and the signal light can be reliably emitted to the display element side. It is possible to prevent variations in luminance and crosstalk from occurring, and high-quality drive display can be performed.
In addition, the manufacturing cost is low, the aperture ratio is high, the driving characteristics are good, the screen size and the definition can be easily increased, and further, the display device can realize the low voltage driving and the low power consumption at the same time. There is. Furthermore, for example, by using an organic EL material, it is possible to realize a display device which has a thin film, a light weight, and flexibility without being made into a film substrate, has low manufacturing cost, and has good productivity. Play.

[Brief description of drawings]

FIG. 1 is a sectional view showing the outline of a first embodiment of a display device according to the present invention.

FIG. 2 is an exploded perspective view schematically showing the display device according to the first embodiment.

FIG. 3 is an energy diagram illustrating the effect of electrons and holes on the injection barrier.

FIG. 4 shows an organic electroluminescent device (two-layer structure) used in Embodiment 1 and a conventional organic electroluminescent device (single-layer structure).
The graph which shows the measurement result of input electric power and light emission brightness.

FIG. 5 is a sectional view showing the outline of a display device according to a second embodiment.

FIG. 6 is a cross-sectional view showing the outline of a display device according to a third embodiment.

[Explanation of symbols]

 a signal light b resonance light d display light 11 display device 12 signal light generating element 13 EL display element 15 half mirror layer 16 row electrode 17 first organic film 18 second organic film 19 signal light generating layer 20 column electrode 21 post-driving electrode 22 Photoconductive Layer 23 Third Organic Film 24 Fourth Organic Film 25 Display Light Generation Layer 26 Front Driving Electrode 27 Resonance Distance Adjusting Film 30 Liquid Crystal Display Element 41 Liquid Crystal

Claims (14)

[Claims] 1. A signal light generating element that generates a signal light in a predetermined wavelength range and controls the amount of light emitted according to the traveling direction of the signal light, a photoelectric conversion layer that generates an electric charge according to the signal light, A display device comprising: a display element in which a region corresponding to a region of the photoelectric conversion layer in which electric charges are generated is driven and displayed. 2. The display device according to claim 1, wherein the signal light generating element causes the signal light in the traveling direction in which the emitted light amount is maximum to be incident on the photoconductive layer. 3. The display device according to claim 1, wherein the signal light generating element is provided with a signal light generating layer that generates the signal light by applying a predetermined voltage. 4. The display device according to claim 3, wherein the signal light generating layer is an organic electric field generating layer. 5. The signal light generating element includes a signal light generating layer that generates signal light in the predetermined wavelength range and a signal light transmitting layer that is transparent to the signal light and is provided on one surface side of the signal light generating layer. First
A plurality of first signal electrodes arranged side by side in the same direction, and on the other surface side of the signal light generating layer, in a second direction different from the first direction, through the signal generating layer, The display device according to claim 1, further comprising: one signal electrode and a plurality of second signal electrodes arranged side by side so as to intersect each other in a matrix. 6. The signal light generating element resonates the signal light to irradiate the display element with the signal light in a predetermined traveling direction, according to any one of claims 1 to 5. Display device. 7. The signal light generating element is provided with a reflecting member that is reflective to the signal light on one surface side of the signal light generating layer, and on the other surface side of the signal light generating layer. The display device according to any one of claims 3 to 6, further comprising a half mirror. 8. The signal light generating element has a pair of electrodes for injecting charges of different polarities into the signal light generating layer, and the reflecting member is any one electrode of the pair of electrodes. The display device according to claim 7, wherein the display device is provided. 9. The signal light generating element has a pair of electrodes for injecting charges of different polarities into the signal light generating layer, the half mirror is a dielectric, and one of the pair of electrodes. The display device according to claim 7, wherein the display device is in contact with the crab. 10. The signal light generating element, wherein the signal light has a distance (l) between the half mirror and the reflecting member with respect to a wavelength (λ) within a predetermined wavelength range of the signal light, where l = nλ The display device according to claim 9, wherein the display device is set to be / 2 (n is a natural number). 11. The signal light generating element according to claim 10, wherein a film thickness of the signal light generating layer is substantially equal to a distance (l) between the half mirror and the reflecting member. Display device. 12. The signal light generating element includes a dielectric film having transparency to the signal light and the signal light generating layer disposed in contact with the dielectric film, and the dielectric film and the signal light generating element. Display device according to claim 10, characterized in that the distance of the layers is substantially equal to the distance (l) between the half mirror and the reflecting member. 13. The display device according to claim 1, wherein the photoelectric conversion layer for generating electric charges by the signal light and a liquid crystal are interposed between a pair of electrodes.
The display device according to any one of the above. 14. The display device according to claim 1, wherein the photoelectric conversion layer for generating charges by the signal light and the organic electroluminescent layer for emitting display light are interposed between a pair of electrodes. ~ The display device according to claim 12.