JP2006310014A - Backlight and electronic display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a backlight device and an electronic display device that can be used in a bent state and can realize low power, high luminance, and long life.
An electronic display device 1A includes a flexible backlight device 2 and an optical modulator 3A, respectively. The backlight device 2 includes an electronic circuit board 21 in which a plurality of light emitting diodes 23 are two-dimensionally mounted on a flexible substrate main body 22, and flexible light emitted from the light emitting diodes 23. This is a device in which diffusable light diffusion sheets 26 and 27 are laminated. A flexible and transparent spacer 25 is interposed between the substrate body 22 and the light diffusion sheets 26 and 27.
[Selection] Figure 1

Description

  The present invention relates to a backlight and an electronic display device.

In general, an electronic display device such as a liquid crystal display device, an electrophoretic display device, an electrodeposition display device, or an electropowder fluid display device uses a light modulator in which a non-luminescent display medium is held by a transparent substrate. Although high contrast display is possible in places, there is a problem that display images are difficult to visually recognize in dark places.
In order to solve such a problem, an electronic display device having a backlight behind an optical modulator has been conventionally developed (see, for example, Patent Document 1).

In the backlight structure described in Patent Document 1, chip LEDs are mounted in a two-dimensional arrangement on a printed circuit board. Then, the light emitted from the chip LED is diffused by hardening the resin from above the chip LED and making the resin surface cloudy glass.
Japanese Laid-Open Patent Publication No. 7-191311 (paragraph 0013, FIG. 1)

Conventionally, a glass provided with a transparent electrode has been mainly used as a transparent substrate for holding a non-luminescent display medium. At present, development for applying a transparent resin film to a transparent substrate is underway because of its advantages such as light weight, thinness, and no cracking. A transparent substrate formed of a transparent resin film has flexibility and is expected to be installed on a curved surface.
As described above, while the development of a transparent substrate having flexibility is advanced, the backlight structure described in Patent Document 1 has one surface of a rigid printed circuit board fixed with resin, and cannot cope with the bending of the transparent substrate. Have the problem.

In addition, as a flexible backlight device compatible with a flexible electronic display device (light modulator), resin-dispersed inorganic electroluminescent elements (inorganic EL elements), organic electroluminescent elements (organic) An element using an EL element) is conceivable.
An inorganic EL element is an element that can be applied to a backlight device using a resin film in which an inorganic fluorescent material that emits light when voltage is applied is dispersed.
An organic EL element is an element in which an organic thin film that emits light by current injection from a transparent electrode can be applied to a backlight device. This organic EL element emits light when organic molecules excited by recombination of electrons and holes injected from a pair of transparent electrodes relax to the ground state.
It is also conceivable to use these inorganic EL elements and organic EL elements as an electronic display device that does not require a backlight.
However, the resin-dispersed inorganic EL element is required to be driven at a high voltage and a high frequency as compared with the light emitting diode, has a problem that power consumption is large, and brightness and life are limited.
In addition, the organic EL element is expected to be thin and have higher flexibility. However, if a thin plastic substrate is used, the gas barrier characteristics are lowered, and the lifetime of the organic EL element is deteriorated due to deterioration of the organic material due to the influence of oxidation and moisture. May be greatly reduced. In addition, there is a problem that the life of the light emitting material itself is shorter than that of the light emitting diode.
Further, when the organic EL element is used as an electronic display device that does not require a backlight, there remains a problem that a technique for separately applying multi-color materials for displaying three primary colors has not been established.

  The present invention has been devised to solve the above-described problem, and can be used in a bent state, and can achieve low power, high luminance, and long life, and a backlight device and an electronic device It is an object to provide a display device.

  In order to solve the above-mentioned problems, an invention according to claim 1 of the present invention is provided on the back side of a flexible light modulator of an electronic display device, and irradiates backlight light to the light modulator. An electronic circuit board in which a plurality of light-emitting diodes are two-dimensionally mounted on a flexible substrate, and light that is flexible and can diffuse light emitted from the light-emitting diodes A diffusion sheet, wherein the electronic circuit board and the light diffusion sheet are laminated.

  In the backlight device configured as described above, light emitted from a plurality of light-emitting diodes arranged two-dimensionally enters the light diffusion sheet. Incident light is diffused by the light diffusion sheet and is emitted as backlight light in a uniform state. Therefore, the backlight device can irradiate the light modulator with uniform backlight light suitable as the backlight device from the emission surface of the light diffusion sheet.

  The invention according to claim 2 is the backlight device according to claim 1, wherein a flexible and transparent spacer is laminated between the substrate and the light diffusion sheet. It is characterized by.

In the backlight device configured as described above, a spacer is interposed between the plurality of light emitting diodes and the light diffusion sheet, and light emitted from the plurality of light emitting diodes passes through the spacer and becomes a light diffusion sheet. It is the structure which injects.
Therefore, the backlight device can secure a space for diffusing the light emitted from the light emitting diodes before entering the light diffusion sheet, and can emit more uniform backlight light.
In the backlight device according to the second aspect, since the spacer is also flexible, it can be bent.

  The invention according to claim 3 is the backlight device according to claim 1 or 2, wherein the substrate is formed of polyimide resin, polyester resin or phenol resin. .

  The backlight device configured as described above can be flexed suitably because the substrate is formed of the material.

  According to a fourth aspect of the present invention, there is provided the backlight device according to the third aspect, wherein the substrate has a thickness of 200 μm or less.

  Since the backlight device configured as described above has a substrate thickness of 200 μm or less, the thickness of the entire device can be suppressed and the device can be more suitably bent.

  The invention according to claim 5 is the backlight device according to any one of claims 1 to 4, wherein the light emitting diode has a height of 1 mm or less from the surface of the substrate. It is implemented as follows.

  In the backlight device configured in this manner, since the height of the light emitting diode is set to the above-described condition, the thickness of the entire device can be suppressed, and adjacent light emitting diodes come into contact with each other when the device is bent. You can avoid that.

  The invention according to claim 6 is the backlight device according to any one of claims 1 to 5, wherein a light reflecting sheet is interposed between the light emitting diodes. It is characterized by that.

  The backlight device configured in this manner can increase the light utilization rate.

  An electronic display device according to a seventh aspect of the present invention includes the backlight device according to any one of the first to sixth aspects, and has flexibility, and is emitted from the light-emitting diodes. And a light modulator that modulates the light diffused by the light diffusion sheet.

The light modulator is a device for spatially modulating light emitted from the backlight device to generate a display image.
Since the electronic display device configured in this manner uses a flexible backlight device and an optical modulator, the electronic display device can be bent.

  The invention according to claim 8 is the electronic display device according to claim 7, further comprising a control device for operating the plurality of light emitting diodes and the light modulator, wherein the plurality of light emitting diodes are: A light emitting diode that individually emits one of the three primary color lights is included, and the control device operates the light modulator according to the light emission period of the light emitting diode that individually emits one of the three primary color lights. It is characterized by that.

  Since the electronic display device configured in this way does not need to use color modulator pixels as the light modulator pixels, the light modulator can be simplified and high resolution can be realized.

  The invention according to claim 9 is the electronic display device according to claim 8, wherein the light modulator modulates light emitted from the light emitting diode and diffused by the light diffusion sheet. And a transparent electrode that applies a voltage to the display medium, and a flexible transparent substrate that holds the display medium and the transparent electrode, and the molecular arrangement of the display medium changes according to the applied voltage. It is characterized by being a liquid crystal.

  The electronic display device configured as described above can have various initial orientations.

  The invention according to claim 10 is the electronic display device according to claim 9, wherein the liquid crystal forms a composite film together with a synthetic resin.

  In the electronic display device configured as described above, since the liquid crystal and the synthetic resin constitute the composite film, the thickness of the composite film is maintained when the electronic display device is bent or an external force is applied, and the liquid crystal Can prevent adverse effects.

The backlight device according to the first aspect can be used in a bent state, and can realize low power, high luminance, and long life.
Further, the backlight device according to claim 2 can emit more uniform backlight light.
Moreover, the backlight apparatus of Claim 3 can bend suitably.
Further, the backlight device according to claim 4 can be thinned and can be more suitably bent.
Further, the backlight device according to claim 5 can be flexed suitably while suppressing adverse effects on the flexibility due to the light emitting diode.
Moreover, the backlight apparatus of Claim 6 can raise the utilization factor as the backlight light of the light which the light emitting diode light-emitted.

In addition, the electronic display device according to the seventh aspect can be bent while realizing low power, high luminance, and long life.
In addition, the electronic display device according to claim 8 has a simple structure and can realize high resolution.
In addition, the electronic display device according to the ninth aspect can have various initial orientations.
In the electronic display device according to the tenth aspect, when the electronic display device is bent or an external force is applied, the thickness of the composite film can be maintained and adverse effects on the liquid crystal can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. Similar parts are denoted by the same reference numerals, and redundant description is omitted. In order to represent the position and direction, a three-dimensional coordinate system (right-handed system) in which the X axis and the Y axis are taken on the surface of the electronic display device and the Z axis is taken in a direction orthogonal to the surface is used. The following drawings schematically show the electronic display device and do not accurately represent the size such as the thickness.

(First embodiment)
First, the electronic display device according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 4 by taking as an example the case where the electronic display device of the present invention is applied to a liquid crystal display device.
FIG. 1 is a schematic cross-sectional view showing an electronic display device according to a first embodiment of the present invention. FIG. 2 is an exploded perspective view showing the electronic display device according to the first embodiment of the present invention. 3A and 3B are schematic cross-sectional views showing the light reflecting sheet and the substrate of FIG. 2, wherein FIG. 3A is a view before assembly, and FIG. 3B is a view after assembly. FIG. 4 is a perspective view of the light diffusing sheet of FIG. 2 viewed from another angle. In FIG. 2, the control device 6 shown in FIG. 1 is omitted.
As shown in FIG. 1, an electronic display device 1A according to a first embodiment of the present invention is a device in which a backlight device 2 and a light modulator 3A are stacked.

<Backlight device>
As shown in FIGS. 1 and 2, the backlight device 2 is provided on the back side of the light modulator 3 </ b> A, and a plurality of light emitting diodes 23 are two-dimensionally mounted on a flexible substrate 22. The electronic circuit board 21, the light reflection sheet 24, the spacer 25, and the light diffusion sheets 26 and 27 are stacked.

<< Board >>
As shown in FIG. 1 and FIG. 2, the substrate 22 is a so-called flexible substrate, and is formed of a synthetic resin having excellent electrical insulation and flexibility. A plurality of light emitting diodes 23 are two-dimensionally mounted on one surface of the substrate 22, and a printed circuit for connecting the plurality of light emitting diodes 23 to the light emitting diode driving device 4 is formed. Note that a known circuit structure can be applied to the printed circuit, and the illustration is omitted for the sake of simplification of the drawing.
As a material of the substrate 22, a polyimide resin, a polyester resin, or a phenol resin excellent in electrical insulation, heat resistance, and mechanical stability is preferable.
The thickness of the substrate 22 is desirably 200 μm or less in order to ensure flexibility and easy mounting of the light emitting diode 23, but flexibility can be ensured if it is 400 μm or less.

≪Light emitting diode≫
As shown in FIG. 2, the light-emitting diode 23 is a surface-mounted / chip-type light-emitting diode, and has a size such that the height from the surface of the substrate 22 after mounting is 1 mm or less.
As the light emitting diode 23 in the present embodiment, a red light emitting diode 23a, a green light emitting diode 23b, and a blue light emitting diode 23c are used. That is, the backlight device 2 includes a light emitting diode that emits one of the three primary color lights having high color purity. As the light emitting diode 23, one type of white light emitting diode can be used instead of the three types of light emitting diodes 23a, 23b, and 23c.
These light emitting diodes 23 are arranged on a surface of the substrate 22 in a grid and at equal intervals. Further, the light emitting diodes 23a, 23b, and 23c are arranged in order, and consideration is given to avoiding direction specificity and in-plane dependence (in-plane non-uniformity of backlight light).
That is, the electronic circuit board 21 is configured by two-dimensionally mounting the light emitting diodes 23 on the board 22.
The number and arrangement of the light-emitting diodes 23 do not have to correspond to the pixel structure of the optical modulator 3A described later, and may be smaller than the number of pixels of the optical modulator 3A, and desired luminance required in the electronic display device 1A. It may be decided according to. In order to obtain high luminance, the mounting density of the light emitting diodes 23 may be increased.
The light emitting diode 23 is not limited to a chip type light emitting diode, and may be a small light emitting diode.

≪Mounting method of light emitting diode≫
Here, an example of a method for mounting the light emitting diode 23 on the substrate 22 will be described by taking as an example the case of using a surface mount type / chip type light emitting diode.
First, a metal thin film (for example, copper) is formed on one surface of the substrate 22. Subsequently, a patterned electrode made of a metal thin film is formed by lithography or etching. Subsequently, cream solder is applied to a predetermined position, and the light emitting diode 23 is disposed thereon. Subsequently, the cream solder is heated and melted, and the light emitting diode 23 and the pattern electrode are connected.
By using this method, a large amount of light emitting diodes 23 can be mounted on the substrate 22 at a time, and the electronic circuit board 21 can be easily manufactured.
The pattern electrode and the light-emitting diode driving device 4 are connected by a lead wire, so that power can be supplied to the light-emitting diode 23.

≪Light reflection sheet≫
As shown to Fig.3 (a), the light reflection sheet 24 is a sheet | seat formed by laminating | stacking the light reflection layer 24a and the insulating layer 24b. A plurality of holes 24 c are formed in the light reflecting sheet 24 in order to allow the plurality of light emitting diodes 23 to be inserted.
As shown in FIG. 3B, the light reflecting sheet 24 is disposed in a state where the light emitting diode 23 is inserted into the hole 24c with the insulating layer 24b facing the substrate 22. The light reflecting sheet 24 is provided between the light emitting diodes 23, prevents light absorption by the substrate 22, and reflects the light emitted from the light emitting diodes 23 by the light reflecting layer 24a. 26 and 27 are incident on the sheet.
The backlight device 2 can increase the utilization factor of light by the light reflecting sheet 24 and improve the luminance. In addition, since the light reflecting sheet 24 includes the insulating layer 24b, the light reflecting sheet 24 is not energized with the printed circuit of the electronic circuit board 21.
Known materials can be used for the light reflecting layer 24a and the insulating layer 24b. For example, an aluminum thin film can be used as the light reflecting layer 24a, and a resin thin film can be used as the insulating layer 24b.

≪Spacer≫
As shown in FIGS. 1 and 2, the spacer 25 is a sheet laminated between the substrate 22 and the light reflecting sheet 24 and the light diffusion sheets 26 and 27, and the light emitting diode 23, the light diffusion sheets 26 and 27, and the like. It is a sheet | seat for hold | maintaining the space | interval of.
In the backlight device 2, a spacer 25 is interposed between the light emitting diode 23 and the light diffusion sheets 26, 27, so that the light emitted from the light emitting diode 23 is allowed to enter the light diffusion sheets 26, 27. It is possible to secure and diffuse light in this space. As a material for the spacer 25, a transparent synthetic resin is suitable.

≪Light diffusion sheet≫
As shown in FIGS. 1, 2, and 4, the light diffusion sheets 26 and 27 are sheets laminated between the spacer 25 and the light modulator 3 </ b> A. The light diffusion sheets 26 and 27 in this embodiment are prism sheets in which saw-like grooves 26 a and 27 a are formed on the side surfaces of the spacer 25.
The light diffusion sheets 26 and 27 are sheets for refracting and diffusing the light emitted from the light emitting diodes 23 so as to be uniformly incident on the incident surface of the light modulator 3A. Make uniform. As a material for the light diffusion sheets 26 and 27, a transparent synthetic resin is suitable.
These light diffusion sheets 26 and 27 are disposed so that the groove portions 26a and 27a are orthogonal to enhance the light diffusion effect, that is, to diffuse light more isotropically. In addition, the light diffusion sheets 26 and 27 desirably have the groove portions 26a and 27a facing the light emitting diode 23 side in order to enhance the light diffusion effect, but are not limited to such a configuration. For example, the structure which uses combining the some light-diffusion sheet from which direction of a groove part differs may be sufficient.

In the illustrated light diffusion sheets 26 and 27, the interval between the groove portions 26a and 27a is constant, but the interval between the groove portions 26a and 27a may be an indefinite period in order to prevent a diffraction phenomenon.
The light diffusing sheet is preferably a sheet having a concavo-convex portion formed on the surface, and is particularly preferably a prism sheet having a saw-like groove portion that diffuses light by refraction.
Also, the number of light diffusion sheets can be set and changed as appropriate. For example, four prism sheets may be arranged such that their groove portions are orthogonal to each other. Moreover, the structure which arrange | positions a part of several light diffusion sheet between a spacer and a light emitting diode may be sufficient.

Here, an embodiment of the backlight device 2 will be described.
As the light emitting diodes 23a, 23b, and 23c, a chip type light emitting diode having an element size of 1.5 mm × 0.8 mm and a height of 0.6 mm is used, and as the substrate 22, a polyimide flexible substrate having a thickness of 150 μm is used. As a result, high-density mounting (interval between light emitting diodes: about 3 mm) on the substrate 22 including the wiring could be realized.
In addition, a transparent vinyl film having a thickness of 2 mm is used as the spacer 25, and four prism sheets having a groove interval of 0.05 mm and an apex angle of 90 degrees are laminated as the light diffusion sheet so that the groove directions are orthogonal to each other. Thus, the uniformity of the backlight light incident on the optical modulator 3A can be realized.

  As a fixing method of the substrate 22, the light reflecting sheet 24, the spacer 25, the light diffusing sheets 26 and 27, and the light modulator 3A described later, for example, a method of adhering these peripheral portions with an adhesive may be used. Other known methods can be used as appropriate.

<Optical modulator>
The light modulator 3A has a structure in which the liquid crystal layer 31 as a display medium is held between a pair of transparent substrates 33 each provided with a transparent electrode 32 for each pixel, that is, a pixel structure. It is an apparatus for generating a display image by spatially modulating the emitted light. An arrow in FIG. 1 represents light as a display image.
Since the pair of transparent electrodes 32 and the transparent substrate 33 are made of flexible resin, the optical modulator 3A has flexibility.

≪Display medium≫
The liquid crystal layer 31 as a display medium is a layer that modulates incident light by changing molecular orientation and changing optical characteristics in response to voltage application from the transparent electrode 32, and has flexibility.
In the case of the electronic display device 1A using the liquid crystal layer 31, that is, a liquid crystal display device, a transmission type method in which the liquid crystal layer 31 is sandwiched between a pair of polarizing films to modulate the transmitted light and perform a display operation is preferable. .
As a material for the liquid crystal layer 31, nematic liquid crystal, cholesteric liquid crystal, smectic liquid crystal (including ferroelectric liquid crystal capable of high-speed operation) and the like are suitable.
In addition, the liquid crystal layer 31 has an initial alignment of liquid crystal molecules, homeotropic (vertical) alignment, homogeneous, by the action of an alignment film (such as a polyimide resin subjected to friction treatment) provided on the transparent electrode 32 (on the side surface of the liquid crystal layer). (Horizontal) orientation, twist orientation, pie-type orientation, hybrid orientation combining vertical orientation and horizontal orientation can also be set. In addition, orientations other than those described above may be used.
In the case where a polarizing plate (polarizing film) that aligns the polarization of incident light and outgoing light is used in the liquid crystal display device 1A, the polarizing film is attached to the transparent substrate 33, for example, and provided integrally with the optical modulator 3A. You can also.

≪Transparent electrode≫
The transparent electrode 32 is an electrode for applying a voltage to the liquid crystal layer 31, and is preferably a metal oxide such as indium oxide-tin oxide (ITO), indium oxide, tin oxide, zinc oxide, indium oxide-zinc oxide. It is.
The transparent electrode 32 is formed by depositing a metal oxide on the transparent substrate 33 using a technique such as a chemical vapor deposition method, a vacuum deposition method, an ion plating method, or a sputtering method. The sputtering method is preferable in consideration of the adhesion to the substrate.
Further, as the transparent electrode 32 other than the metal oxide, a transparent organic conductive material such as a polythiophene resin is suitable.
In this case, the transparent electrode 32 is formed by applying a thin film on the transparent substrate 33 using a technique such as spin coating or printing.

≪Transparent substrate≫
The transparent substrate 33 is a flexible substrate on which the transparent electrode 32 is formed and holds the liquid crystal layer 31 facing each other.
As the material for the transparent substrate 33, polycarbonate, polyethersulfone, polyethylene terephthalate, polyarylate, and the like excellent in optical properties such as light transmittance are suitable.
The thickness of the transparent substrate 33 is preferably 5 to 500 μm, more preferably 50 to 200 μm.
Moreover, it is preferable that the light transmittance in visible light of the transparent substrate 33 is 80% or more.
In order to ensure the operational stability of the optical modulator 3A, a gas barrier layer composed of a thin film made of an inorganic material may be formed on the transparent substrate 33.
As the thin film made of such an inorganic material, a SiO _x (1.0 ≦ X ≦ 2.0) film, a SiN film, or a multilayer film thereof is suitable.

The light emitting diode 23 is driven by the light emitting diode driving device 4, and the light modulator 3 </ b> A is driven by the light modulator driving device 5.
The light emitting diode driving device 4 is a device for driving the light emitting diode 23 by a light emitting diode power source, and includes a switching circuit. The power supply for the light emitting diode supplies current or voltage to the light emitting diode 23. By switching the connection state of the switching circuit, the control device 6 can switch the current (voltage) supply state to the light emitting diodes 23a, 23b, and 23c, and can cause the light emitting diodes 23a, 23b, and 23c to emit light for each type.
The optical modulator driving device 5 is a device for driving the optical modulator 3A by the optical modulator power source, and includes a switching circuit. The power supply for the light modulator supplies current or voltage to the transparent electrode 32 of the light modulator 3A. The control device 6 can switch the current (voltage) supply state to the transparent electrode 32 by switching the connection state of the switching circuit, and can switch the voltage application state for each pixel of the optical modulator 3A. In addition, when using a white light emitting diode as the light emitting diode 23, a switching circuit is unnecessary.
A commercial power supply, a battery, etc. can be used as various power supplies.

When the backlight device 2 includes an array of light emitting diodes 23a, 23b, and 23c that emit one of the three primary colors, the control device 6 takes advantage of the high-speed response of the light emission to make the light emitting diodes 23a, 23a, Color display can be realized by causing the three primary colors to sequentially emit light at 23b and 23c at high speed and operating the light modulator 3A according to the light emission period (field sequential color display method).
In this field sequential color display system, it is not necessary to make the pixel of the light modulator 3A a color pixel corresponding to one of the three primary colors, so that the light modulator 3A and each of the driving devices 4 and 5 can be simplified. An electronic display device 1A having a resolution can be provided.
When the electronic display device 1A is applied to a television, the light emission period is 3N times (N is an integer of 1 or more) the frame frequency (or field frequency) of the video signal.

Here, the operation of the electronic display device 1A according to the first embodiment will be described.
FIG. 5 is a schematic cross-sectional view showing a state where the electronic display device according to the first embodiment of the present invention is bent.
As shown in FIG. 5, the backlight device 2 is a device in which a flexible substrate 22, a light reflecting sheet 24, a spacer 25, and light diffusing sheets 26 and 27 are laminated. When the optical modulator 3 </ b> A having the deflection is bent, it can be bent following the bending shape. Therefore, the entire electronic display device 1A has flexibility and can be used in a bent state.
In addition, since the backlight device 2 uses the light emitting diode 23, it is possible to realize lower power, higher luminance, and longer life as compared with the case where an EL element is used.
Further, since the backlight device 2 includes the light diffusing sheets 26 and 27, the backlight device 2 can emit uniform backlight light.
In addition, since the backlight device 2 includes the spacer 25 between the light emitting diode 23 and the light diffusion sheets 26 and 27, a space corresponding to the thickness of the spacer 25 can be secured, and the light emitting diode 23 is generated. Space for the diffused light can be obtained.
In addition, since the backlight device 2 includes the light reflecting sheet 24 between the light emitting diodes 23, it is possible to prevent the generation of interference fringes, increase the light utilization rate, and improve the luminance.
Further, since the backlight device 2 can adjust the size of the substrate 22 to the size of the optical modulator 3A, the number of light emitting diodes 23 mounted on the substrate 22 can be reduced even if the optical modulator 3A is enlarged. The desired luminance can be obtained.
In addition, since the height of the light emitting diode 23 from the substrate surface of the substrate 22 in the mounted state is 1 mm or less, the backlight device 2 can suppress the thickness of the entire device and emit light when the device is bent. The contact between the diodes 23 can be avoided, and the adverse effect of the light emitting diodes 23 on the flexibility can be suppressed.

(Second embodiment)
Next, an electronic display device 1B according to the second embodiment of the present invention will be described focusing on differences from the electronic display device 1A according to the first embodiment.
FIG. 6 is a schematic cross-sectional view showing an electronic display device according to the second embodiment of the present invention.
As shown in FIG. 6, the liquid crystal 34a which is a display medium according to the second embodiment of the present invention forms a composite film 34 together with a fine polymer structure 34b.
The polymer structure 34b is an example of the “synthetic resin” in the claims, and when the electronic display device 1B is bent or an external force is applied, the distance between the two transparent substrates 33, 33, that is, It plays the role of keeping the thickness of the composite film 34 constant.
As a method for producing such a composite film 34, a phase separation method using photopolymerization, thermal polymerization, solvent evaporation, or an impregnation method in which liquid crystal is impregnated into a porous resin is suitable.
As the shape of the polymer structure 34b, various shapes such as a shape including liquid crystal droplets, a mesh shape, a particle shape, and a wall shape can be adopted. In FIG. 6, as an example, a shape including a droplet of the liquid crystal 34a is depicted.
Further, the electronic display device 1B provided with the composite film 34 uses a polarizing plate (polarizing film) because light scattering at the composite film 34 can be controlled by changing the liquid crystal alignment. The electronic display device 1 </ b> B that can perform a display operation even without it and can perform a brighter display operation can also be configured.

The embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and can be appropriately changed in design without departing from the gist of the present invention.
For example, as long as the flexibility of the electronic display device can be ensured, sheets, films, and the like having other functions can be interposed.
Further, the electronic display device may use various white light emitting diodes having excellent color rendering properties as the light emitting diodes, and may be provided with a micro color filter in each pixel of the light modulator.
Further, the electronic display device 1 </ b> A according to the first embodiment may have a configuration in which a spacer is provided in the liquid crystal layer 31. As such a spacer, spherical plastic particles or silica particles are suitable.
Moreover, the light transmittance of the spacer 25, the light diffusion sheets 26 and 27, the transparent electrode 32, and the transparent substrate 33 can be changed as appropriate.
The material of the substrate 22 may be any material that can achieve the desired flexibility, and may be a resin made of liquid crystal polymer (LCP), polyethylene naphthalate (PEN), polyetheretherketone (PEEK), or the like. good. Further, even a substrate made of a glass / epoxy material can be applied to the substrate 22 because desired flexibility can be realized by setting the thickness to 0.2 mm or less.

In addition, as an optical modulator using other than liquid crystal, fine particles (pigments, etc.) that are colored or clouded in a fluid (liquid or gas) sandwiched between transparent substrates by electrostatic force accompanying voltage application move or rotate, and light An optical modulator to which an electrophoresis method and a toner method in which the absorption state changes may be applied.
Moreover, the light modulator which applied the electrodeposition system which controls the ionization and precipitation of metals (silver etc.) in electrolyte solution by the current injection from a transparent electrode, and changes the absorption state of external light may be used.
Furthermore, it may be an optical modulator to which an electro-powder fluid system using a resin-made powder fluid having a property of being very fine and easily charged and moving by an electric field is used as a display medium.

1 is a schematic cross-sectional view showing an electronic display device according to a first embodiment of the present invention. 1 is an exploded perspective view showing an electronic display device according to a first embodiment of the present invention. (A) is a schematic cross section which shows a light reflection sheet, (b) is a schematic cross section which shows the state which laminated | stacked the light reflection sheet on the board | substrate. It is the perspective view which looked at the light-diffusion sheet | seat of FIG. 2 from another angle. It is a schematic cross section which shows the state which bent the electronic display apparatus which concerns on 1st embodiment of this invention. It is a schematic cross section which shows the electronic display apparatus which concerns on 2nd embodiment of this invention.

Explanation of symbols

1A, 1B Electronic display (liquid crystal display)
2 Backlight device 3A, 3B Light modulator 4 Light emitting diode drive device 5 Light modulator drive device 21 Electronic circuit board 22 Substrate 23 Light emitting diode 23a Red light emitting diode 23b Green light emitting diode 23c Blue light emitting diode 24 Light reflecting sheet 24a Light reflecting Layer 24b Insulating layer 24c Hole 25 Spacer 26 Light diffusion sheet (prism sheet)
26a Groove (uneven portion)
27 Light diffusion sheet (prism sheet)
27a Groove (uneven portion)
31 Liquid crystal layer (display medium)
32 Transparent electrode 33 Transparent substrate 34 Composite film 34a Liquid crystal (display medium)
34b Polymer structure (synthetic resin)

Claims (10)

A backlight device that is provided on the back side of a flexible light modulator of an electronic display device and irradiates backlight light to the light modulator,
An electronic circuit board in which a plurality of light emitting diodes are two-dimensionally mounted on a flexible board;
A light diffusion sheet having flexibility and capable of diffusing light emitted from the light emitting diode;
With
A backlight device, wherein the electronic circuit board and the light diffusion sheet are laminated.   The backlight device according to claim 1, wherein a flexible and transparent spacer is laminated between the substrate and the light diffusion sheet.   The backlight device according to claim 1, wherein the substrate is formed of a polyimide resin, a polyester resin, or a phenol resin.   The backlight device according to claim 3, wherein the substrate has a thickness of 200 μm or less.   The backlight device according to any one of claims 1 to 4, wherein the light emitting diode is mounted so that a height thereof is 1 mm or less from a surface of the substrate.   The backlight device according to any one of claims 1 to 5, wherein a light reflection sheet is interposed between the light emitting diodes. The backlight device according to any one of claims 1 to 6,
A light modulator having flexibility and modulating light emitted from the light emitting diode and diffused by the light diffusion sheet;
An electronic display device characterized by being laminated. A controller for operating the plurality of light emitting diodes and the light modulator;
The plurality of light emitting diodes include light emitting diodes that individually emit one of the three primary colors,
8. The electronic display device according to claim 7, wherein the control device operates the light modulator according to a light emission period of a light emitting diode that individually emits one of the three primary color lights. The light modulator is
A display medium that modulates light emitted from the light emitting diode and diffused by the light diffusion sheet;
A transparent electrode for applying a voltage to the display medium;
A transparent substrate having flexibility and holding the display medium and the transparent electrode;
With
9. The electronic display device according to claim 8, wherein the display medium is a liquid crystal whose molecular arrangement changes with an applied voltage.   The electronic display device according to claim 9, wherein the liquid crystal forms a composite film together with a synthetic resin.

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