JPH10186361A - Display device and driving method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device capable of obtaing an uniform display state and capable of reducing the number of components of the device, reducing the cost of the device, and making the device thinner and light in weight in a liquid crystal display device, in which an illuminating part consisting of a light source is arranged on the side face of a display panel, and to provide its driving method. SOLUTION: This display device is provided with a display panel, in which a dimmer layer 3 consisting of liquid crystal material whose transparent state and transmission state are controlled by impressed voltages is held between one pair of substrates 1, 5, in which plural scanning electrodes are arranged on the surface of the substrate of one side and a single or plural information electrodes are arranged on the surface of an opposed substrate or between one pair of substrates 1, 5, in which plural scanning electrodes and a single or plural information electrodes are arranged on the surface of the substrate of one side and an illuminating part consisting of a light source 6 to be arranged at the side face in a direction orthogonally crossing the side of the scanning electrodes of the display panel and the device is constituted so that light beams from the illuminating part are made incident on the side face of the display panel to be transmitted to the substrate 5 constituting the display panel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device applied to a flat panel display such as a liquid crystal display device mounted on a notebook personal computer, a word processor, a portable information terminal or the like, and a driving method thereof.

[0002]

2. Description of the Related Art A transmission type liquid crystal display is mainly mounted as a display device such as a notebook computer or a word processor at present. Here, the conventional transmission type liquid crystal display provided with a backlight will be described with reference to FIG.

As shown in FIG. 9, in this transmission type liquid crystal display, a color filter 8 and an electrode 2 are sequentially formed on one surface of an upper substrate 1, an electrode 4 is formed on one surface of a lower substrate 5, and these electrodes 2 are formed. The liquid crystal layer 3 is sandwiched between the upper substrate 1 and the lower substrate 5 such that the electrodes 4 face each other, and the polarizing plate 9a on the display surface side of the upper substrate 1 and the polarizing plate 9b on the backlight portion side of the lower substrate 5 Are provided. A fluorescent tube 6 serving as a light source, a lamp reflector 7 covering the light source, a light guide plate 11 for guiding light from the fluorescent tube 6 to the liquid crystal panel, a dimming layer 12 and a reflector disposed below the light guide plate 11 The backlight unit 13 is disposed on the back surface of the liquid crystal panel via the air layer and the diffusion sheets 10 to constitute a transmissive liquid crystal display. This transmission type liquid crystal display has electrodes 2 and 4
By supplying a liquid crystal driving signal to the liquid crystal layer 3 to control the liquid crystal layer 3, display becomes possible.

Next, the principle of orientation of the liquid crystal panel of the transmission type liquid crystal display will be described with reference to FIG. Most of liquid crystal substances are organic compounds composed of elongated rod-like molecules, and in a natural state, are arranged with a gradual regularity in the major axis direction of the molecules. When liquid crystal molecules are brought into contact with an alignment film having fine grooves in a certain direction, the liquid crystal molecules have a property of being arranged along the grooves. For example, utilizing its properties, FIG.
As shown in FIG. 0 (a), when the liquid crystal is supported between the alignment films 12a and 12b in which the directions of the grooves are different by 90 degrees, the liquid crystal molecules are arranged in a twisted state by 90 degrees. When the liquid crystal twisted by the alignment films 12a and 12b is supported between the two polarizing plates 9a and 9b whose polarization directions are orthogonal to each other, light incident from above the polarizing plate 9a becomes
Since it is twisted 90 degrees along the gap between liquid crystal molecules, the polarizing plate 9
b, which is turned on (transmitted).

Then, as shown in FIG. 10 (b), when a voltage 13 is applied, the liquid crystal molecules are erected and twisted.
Then, the light incident from the upper part of the polarizing plate 9a is directed to the polarizing plate 9b in the same polarization direction, so that the light is not transmitted, and the light is turned off.

A display device utilizing such a principle is called a normally white type twisted nematic (TN) type liquid crystal display device. The TN type liquid crystal display device is roughly classified into the following two types. You. One of them is shown in FIG.
As shown in (a), the liquid crystal display device is a simple matrix type liquid crystal display device, in which a scanning electrode is arranged on one substrate and an information electrode is arranged on the other substrate. Then, a selection voltage is applied to the scanning electrodes by line-sequential scanning, and an ON voltage or an OFF voltage is applied to the information electrodes in synchronization with the selection voltage.
At this time, an intermediate voltage between the ON voltage and the OFF voltage is applied as a non-selection voltage to the scan electrode to which the selection voltage is not applied. By this scanning, the liquid crystal constituting the pixel can be selectively turned on or off.

The other is an active matrix type liquid crystal display device shown in FIG. The structure, instead of the scanning electrodes of the simple matrix type liquid crystal display element,
A gate electrode connected to a gate terminal of an FET element provided for each pixel is provided on the same substrate as an information electrode. Then, as the driving, a voltage for turning on the FET element is applied by line-sequential scanning to the gate electrode, and charges are injected from the information electrode connected to the source terminal to the pixel electrode connected to the drain terminal. This is a method of controlling the potential applied to the liquid crystal interposed between the pixel electrode and the counter electrode (the arrow in the figure) to perform display.

In any TN type liquid crystal display device, two polarizing plates are required to fulfill the role of an optical shutter by utilizing the twist of liquid crystal molecules. However, when two polarizing plates are arranged in a parallel Nicols state, the transmittance is 30%.
It is as low as ~ 40%.

[0009]

Therefore, it is conceivable to use a light scattering type liquid crystal which does not require a polarizing plate instead of the TN type liquid crystal. The light scattering type liquid crystal is Hikm
et. (Philips) Mol.Cryst.Liq.Cryst., 1
992, Vol. 1.213, pp. 117-131, network oriented polymer dispersed liquid crystal, and Japanese Journal of Applied Physics, 1984, Vol. 2 by Katsumi Yoshino (Osaka University) et al.
Light scattering type smectic liquid crystals proposed in 3, No. 6, pp. 385-387 are known.

However, in such a scattering state of the light-scattering type liquid crystal, 10 to 30% of the incident light is reflected or transmitted, so that it is practically used as a projection type display. However, it has been difficult to put it to practical use as a direct-view display using a backlight. That is, even if the backlight unit is placed on the back surface of such a light-scattering type liquid crystal panel, since about 10% of the back light is transmitted by the pixels in the scattering state, 100% of the back light is transmitted by the pixels in the transmission state. Is transmitted, the contrast is 10 or less, and there is a practical problem.

In order to solve these problems, Japanese Patent Application Laid-Open No. 3-73926 proposes a structure using a film-like liquid crystal layer and disposing a light source on a side surface of a liquid crystal panel substrate. However, the driving method described in this publication turns on and off the entire surface of the liquid crystal panel at the same time, so that no matter how much space is provided between pixels, if all the pixels are in a scattering state, they are provided on the side of the substrate. The display becomes darker as the distance from the light source increases, and the display quality becomes non-uniform.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a uniform display state can be obtained in a liquid crystal display device in which an illuminating section comprising a light source is arranged on a side surface of a display panel. It is an object of the present invention to provide a display device which can reduce the number of parts of the device, reduce cost, and reduce the thickness and weight, and a driving method thereof.

[0013]

According to the present invention, a plurality of scanning electrodes are arranged on one substrate surface and one or more information electrodes are arranged on an opposing substrate surface. Between a pair of substrates or between a pair of substrates in which a plurality of scanning electrodes and one or a plurality of information electrodes are arranged on one substrate surface, a transparent state and a transmission state are formed of a liquid crystal material or the like controlled by an applied voltage. A display panel having a light control layer sandwiched between the display panel and a lighting unit including a light source disposed on a side surface of the display panel in a direction orthogonal to the scanning electrode side, and light from the lighting unit is incident on the side surface of the display panel. The substrate constituting the display panel is configured to guide light.

That is, in the present invention, light from a light source such as a fluorescent tube is made to enter the display panel from a side surface of the display panel in a direction orthogonal to the scanning electrodes. this is,
When at least one of the upper substrate and the lower substrate constituting the display panel is used as a light guide, if an illuminating unit is arranged on the side of the display panel in a direction parallel to the scanning electrodes, there are many pixels in a scattering state on the scanning electrodes. Since light propagating in the plane of the display panel decreases as it goes away from the light source, this is prevented, and a uniform display state can be obtained. This will be described with reference to FIG. 1 showing an optical path of light emitted from the light source of the illumination unit on the display panel. If the illumination unit is arranged on the side of the display panel in a direction parallel to the scanning electrodes of the display panel, FIG. As shown in FIG. 1A, the light propagating in the display panel decreases as the distance from the light source increases. On the other hand, when the light from the light source is incident on the display panel from the side surface in the direction orthogonal to the scanning electrodes of the display panel as in the present invention, the inside of the display panel surface is reduced as shown in FIG. Since the propagating light hardly decreases, a uniform display state can be obtained.

Further, according to the present invention, in the above display device, the light control layer is made of a liquid crystal material having optical anisotropy such as a polymer dispersed liquid crystal material or a smectic liquid crystal material. Further, as the liquid crystal material, a mixture of dichroic dyes is used. When a mixture of dichroic dyes is used as the light control layer, both the upper substrate and the lower substrate can be used as a light guide plate. In this case, if the upper and lower substrates are used simultaneously as a light guide, the in-plane light efficiency of the light guide can be improved.

Further, according to the present invention, in the above-described display device, a reflection mechanism is provided on a side surface of the substrate constituting the display panel where the illuminating section is not arranged. That is, by providing a reflection mechanism such as bonding a white resin sheet to all side surfaces of the substrate functioning as the light guide that are not adjacent to the illuminating portion, the in-plane light reflection efficiency of the substrate serving as the light guide is improved. Can be done.

Further, according to the present invention, in the above display device, the lower substrate opposite to the display surface forming the display panel is a transparent substrate, and at least one surface of the lower substrate is colored, or A colored body is arranged on the back surface.

This is because when the light control layer is composed of a polymer dispersed liquid crystal (hereinafter referred to as PDLC),
If C has excellent forward scattering efficiency, it is preferable to use the lower substrate on the illuminating section side constituting the display panel as a light guide. And, using a transparent substrate as an upper substrate and a lower substrate constituting the display panel,
It is only necessary to arrange the illuminating part adjacent to the side surface of the lower substrate, and if a colored body such as a black sheet is arranged so as not to adhere to the back surface of the lower substrate, or if the back surface of the lower substrate is colored, the contrast value is improved. That can be done.

Further, according to the present invention, in the above display device, the lower substrate constituting the display panel is configured to also serve as the frame. In other words, by using aluminum or the like (a member having no effect of ions) which also serves as a frame outer frame as a lower substrate, the device can be made thinner and lighter. Note that as the lower substrate also serving as the frame, it is preferable to use a member other than glass that has no influence of ions or a member that has been subjected to a process of eliminating the influence of ions. In addition, it is preferable that the surface of the lower substrate be colored white, and if the entire surface is colored, the propagation efficiency in the optical plane is deteriorated, so that it is preferable to apply the color in units of one pixel or several pixels. Further, in consideration of the in-plane distribution of light, coating with gradation from white to gray is also preferable.

In the display device of the present invention, when the substrate forming the display panel is a transparent substrate, it is preferable that the substrate be made of a material having a refractive index higher than that of the light control layer (liquid crystal layer (transparent state)). Further, it is preferable that the illumination unit is provided with a lamp reflector as a reflecting mirror around a light source of the fluorescent tube.

Further, according to the present invention, in the above-described method for driving a display device, a selection voltage is applied to a scanning electrode selected from the scanning electrodes, and a light control layer is selectively selected by a potential difference from the selection voltage. To the information electrodes, and apply a voltage to make the dimming layer transparent regardless of the voltage applied to the information electrodes to the scanning electrodes that are not selected among the scanning electrodes. And

That is, as a driving method of the above-mentioned display device, a selection voltage is applied to a selected scanning electrode, and a light control layer is selectively transparent (transmitted) to an information electrode by a potential difference from the selection voltage. A voltage for making the opaque (scattering) state is applied, and a voltage for making the light control layer transparent is always applied to the other scanning electrodes regardless of the voltage of the information electrode. With this configuration, light propagating in a display panel such as a liquid crystal panel is not scattered by unselected scanning electrodes, but is scattered only by the selected scanning electrodes. This solves the problem that the display becomes darker as the distance from the light source of the illumination unit increases, and the display quality becomes uneven. In this case, both the plurality of scanning electrodes and one or more information electrodes are formed on one substrate surface, and the light modulating layer is selectively made transparent or opaque according to the potential difference between the scanning electrodes and the information electrodes. Is also possible.

In the case of a material in which the light control layer is in a scattering state by application or interruption of a voltage, such as a liquid crystal layer composed of PDLC, the scattering portion (pixel) is illuminated with external light to illuminate or display. Since it becomes a body, it becomes possible to eliminate the need for members such as a polarizing plate and a diffusion plate. In the case of color display, an illuminance is provided only with external light because the illuminance is insufficient and display visibility is poor. However, this illuminator is used as a light guide plate for a substrate forming the display panel itself. Arranged so that light is incident from the side, using a line-sequential scanning drive system, when a specific number of single electrodes or a plurality of simultaneous scans are completed, regardless of the potential difference between the scanning electrodes and the information electrodes, the liquid crystal layer By controlling the display body area by providing a period (a non-scanning period until the next scanning starts) in which a voltage is applied to the light control layer so that the light control layer is in a transparent state, the display uniformity and contrast are improved. Can be improved.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. One of the panel configurations of the embodiment of the present invention is that a plurality of scanning electrodes are formed on one substrate surface, and a single or a plurality of information electrodes are formed on the other opposing substrate surface. This is a display panel in which a dimming layer made of a polymer-dispersed liquid crystal (hereinafter, referred to as PDLC) or a light-scattering smectic liquid crystal which is brought into a transparent (transmissive) state or an opaque (scattering) state by voltage is sandwiched. In another panel configuration, a plurality of scanning electrodes and one or more information electrodes are both formed on the surface of one substrate, and the light modulating layer is selectively transparent by a potential difference between the scanning electrodes and the information electrodes. (Transmissive) state or opaque (scattering) state.

For PDLC, biphenyl methacrylate is used as a polymer precursor and mixed with a low-molecular liquid crystal material containing a chiral component.
As a result of polymerization by irradiation with ultraviolet light having a wavelength of 350 nm, a polymer is formed in an aligned state, and a liquid crystal layer (light control layer) having a structure in which liquid crystal is included in a gel network is produced. Such a liquid crystal layer scatters white when an electric field is applied, and is called a reverse mode.

This PDLC was manufactured by adjusting the liquid crystal component, cell thickness, and ultraviolet irradiation time, and performed an operation in which the scattering component increased in gradation between an applied voltage of 20 V and 30 V. At this time, when an AC voltage of 15 V is applied to the scanning electrode and an AC voltage of 15 V is applied to the information electrode, the pixel is scattered white in a pixel where the potential difference between the two becomes 30 V, and the potential difference between the two becomes O.
The pixel which becomes V is in a transparent state.

The light scattering type smectic liquid crystal panel was manufactured by injecting CS1014 manufactured by Chisso Corporation into a cell having a thickness of 10 μm using PVA as an alignment film.
The display panel made of the smectic liquid crystal is in a transmissive state when a positive or negative voltage is always applied, but is temporarily in a light scattering state when a voltage of opposite polarity is applied.
Therefore, during the odd frame period, a voltage of +5 V is applied to the unselected scanning electrodes of the liquid crystal panel, and an OV voltage is applied to the selected scanning electrodes. At this time, when a voltage of -5 V is applied to the information electrode, the voltage polarity of the selected pixel does not change, so that the liquid crystal forming the pixel remains in a transmissive state. However, when a voltage in the range of OV to +5 V is applied to the information electrode, the voltage polarity of the selected pixel changes, so that the liquid crystal forming the pixel temporarily becomes a scattered state, and the scanning electrode again becomes a non-selected state. Again, it temporarily becomes a scattering state again. At this time, the observed light differs between when +1 V is applied to the information electrode and when +5 V is applied.

In order to cancel the DC component of the voltage applied to the liquid crystal, during an even frame period, a voltage of -5 V is applied to the unselected scanning electrodes of the liquid crystal panel, and to the selected scanning electrodes. OV voltage is applied. At this time, when a voltage of +5 V is applied to the information electrode, the voltage polarity of the selected pixel does not change, so that the liquid crystal forming the pixel remains in a transmissive state. However, when a voltage in the range of OV to -5 V is applied to the information electrode, the voltage polarity of the selected pixel changes, so that the liquid crystal constituting the pixel temporarily becomes in a scattering state, and the scanning electrode is again in a non-selected state. When this happens, it again becomes temporarily scattered. In this example, 1
The selection period is about 400 microseconds.

[First Embodiment] A first embodiment of the present invention will be described below with reference to FIGS. FIG.
FIG. 3 is a conceptual cross-sectional view showing optical characteristics of a liquid crystal panel which is a display panel of the display device according to the first embodiment of the present invention.
This is a display device that improves the efficiency of light emission to the observer when the forward scattering efficiency of the LC is high.

Glass (refractive index: ng =
1.52) using a polymer liquid crystal material (refractive index when transparent:
(n1 = 1.54, refractive index at scattering: n2 = 1.75) was used. Each of the electrodes 2 and 4 was formed with an ITO film (refractive index: ni = 1.84). In the first embodiment, it is preferable that n2 ≧ ni>ng> n1 holds.

When light propagates from a medium having a large refractive index to a medium having a small refractive index among light components traveling inside the liquid crystal panel, total reflection occurs when the incident angle is equal to or larger than the critical angle. The critical angle of light totally reflected by propagation from the upper substrate or the lower substrate to the air layer is represented by the following equation according to Snell's law.

Sin θg ≧ (n / ng) In the above formula and FIG. 1, θg is the reflection angle on the glass substrate 1 surface (g), and θi is the surface of the ITO electrode 4 at the interface with the liquid crystal layer 3 (i ), The reflection angle of light on the surface (i) of the ITO electrode 4 at the interface with the glass substrate 5, θ1i is the incident angle from the liquid crystal layer 3 to the ITO electrode 4,
θgi is the angle of incidence from the glass substrate 1 to the ITO electrode 2, n
Is the refractive index of air, and ng is the refractive index of glass.

Next, in the propagation from the upper substrate 1 or the lower substrate 5 to the electrode 2 or the electrode 4, light is incident from a medium having a small refractive index to a medium having a large refractive index. The incident light is divided into reflected light and transmitted light. this is,
The same occurs when the light propagates from the liquid crystal layer 3 to the electrode 2 or the electrode 4. Here, when the liquid crystal layer 3 is made opaque by the application of an AC electric field, light components traveling from the light source through the opaque liquid crystal portion to the upper substrate 1 and the liquid crystal layer 3 are scattered and turned on. become.

In the structure of this embodiment shown in FIG. 3 described later, the maximum luminance was 480 cd / m ² , but the uniformity was poor and the minimum luminance was 320 cd / m ² . This is a value when the entire surface is displayed in a solid display (entire scattering state). Line-sequential scanning is employed as a driving method of this display device, and a period in which OV is applied to all the scanning electrodes (or all the scanning electrodes are connected to the ground) is provided when scanning of 80 electrodes is completed, so that instantaneous scanning is performed. First, all the pixels were made transparent. When this operation was repeated, the maximum luminance was 410 Cd / m ² and the minimum luminance was 370 Cd / m ^2, and the uniformity was improved. In the case of a liquid crystal layer which changes from a scattering state to a transparent state by applying a voltage, a period in which all the scanning electrodes and all the information electrodes are set to OV is provided.

FIG. 3 is a sectional view showing a main part of a schematic structure of the display device of the first embodiment. As shown in FIG. 3, the main configuration of this display device is an upper substrate (glass substrate) 1a (0.7 mm thick) having the above-described optical characteristics, an electrode (ITO).
2, a display panel in which a liquid crystal layer 3, an electrode (ITO) 4, and a lower substrate (glass substrate) 5a (thickness: 2.8 mm) are sequentially laminated, and a lighting unit including a fluorescent tube 6 and a lamp reflector 7 Is what is done. The lower substrate 5
The reason why the thickness of “a” is larger than the thickness of the upper substrate 1a is that the structure of this embodiment uses the lower substrate as a light guide because the forward scattering efficiency of the PDLC is high, This is because the light from 6 is efficiently incident on the lower substrate 5a.

A cold-cathode tube 2.6 (diameter 2.6 mm) is disposed adjacent to the side surface of the lower substrate 5a as the fluorescent tube 6 as described above. Around the fluorescent tube 6, there is arranged a lamp reflector 7 on the fluorescent tube side of which metal such as silver or aluminum is vapor-deposited or metal-plated and which is subjected to an insulating film treatment.

Although not shown, all the side surfaces of the upper substrate 1a where the fluorescent tubes 6 are not disposed are provided with a reflection mechanism in which a white resin tape is adhered and integrated using a transparent adhesive. It has a structure that enhances the efficiency of using reflected light.

There is a lower substrate 5a on which the electrodes 2 are formed in a stripe pattern and a polymer liquid crystal layer 3, and the thickness of these portions is 2.8 mm. The total thickness of the liquid crystal panel is 3.5 mm, which is 65% of a conventional standard liquid crystal panel.

On the back side of the lower substrate 5a, a colored substrate 14 dyeing a dyeable resin and dyeing black was disposed. This black coloring is for obtaining high contrast. Similarly it was set the tube current of the fluorescent tube 6, when the liquid crystal layer 3 is opaque to obtain the brightness of ^{390cd / m 2, 8.8cd / m} 2 becomes the time the liquid crystal layer 3 is transparent, the contrast = 44: 1 was obtained.

Second Embodiment Hereinafter, a second embodiment of the present invention will be described with reference to FIG. As shown in FIG. 4, which is a cross-sectional view of a main part schematically showing the structure of the display device of the second embodiment, a color is provided on the display surface side surface of the upper substrate 1a of the first embodiment shown in FIG. The filter 8 is provided. In the second embodiment, when the tube current of the fluorescent tube 6 is set in the same manner as in the first embodiment, a white luminance of 74 cd / m ² is obtained when the liquid crystal layer 3 is opaque. When the layer 3 was transparent, the luminance was 4.4 Cd / m ² , and a contrast of 17: 1 was obtained.

Third Embodiment Hereinafter, a third embodiment of the present invention will be described with reference to FIGS. When the backscattering efficiency of the PDLC used for the liquid crystal layer is high, this mechanism can efficiently emit light to the observer. Therefore, in the third embodiment, as shown in FIG. 5 which is a cross-sectional view of a main part schematically showing the configuration, the arrangement of the illumination unit composed of the fluorescent tube 6 is changed to the side surface of the upper substrate 1b and the liquid crystal layer 3. . A colored substrate dyed black using a dyeable resin was provided on the back surface of the lower substrate 5b. The thicknesses of the upper substrate 1b and the lower substrate 5b were also different from those of the first embodiment, and the thickness of the upper substrate 1b was 2.8 mm, and the thickness of the lower substrate 5b was 0.7 mm.

The schematic configuration of the third embodiment in which the color filter 8 is provided on the display surface side surface of the upper substrate 1b is as shown in the sectional view of the main part of FIG.

[Fourth Embodiment] Hereinafter, a fourth embodiment of the present invention will be described with reference to FIGS. The display device of the fourth embodiment has an upper substrate 1c also serving as a light guide, a PDL, as shown in a main portion sectional view showing a schematic configuration thereof.
A display panel including a liquid crystal layer 3 ′ containing a dichroic (black) dye in C, a lower frame and lower substrate 5 c also serving as a lower frame, and an illuminating unit similar to the first to third embodiments. 6 ′, a scanning driver board 15, and an upper frame 16.

In this fourth embodiment, the lower substrate constituting the liquid crystal panel employs the lower frame and lower substrate 5c which also serves as a frame, so that the device can be made thinner and lighter.

Further, the lower frame and lower substrate 5c of this embodiment
As shown in FIG. 8 which is a top view of FIG.
Is colored with a white colored body 17. In this coloring, if the entire surface is colored, the propagation efficiency in the light plane deteriorates. Therefore, as shown in FIG. 8, it is preferable to apply the coloring in one pixel unit or several pixel units. Further, in consideration of the in-plane distribution of light, coating with gradation from white to gray is also preferable.

The size of the display panel (liquid crystal panel) in the display devices of the first to fourth embodiments is 6 inches (13 inches).
0 × 74 Cmm2]) and a substrate equivalent to 320 × 240 dots.

In the above embodiment, at least one surface of the upper substrate on the display side constituting the display panel (liquid crystal panel) may be colored with a mask corresponding to a single or a plurality of pixels.

[0048]

As described above, according to the present invention,
Special members such as a polarizing plate and a light guide plate are not required, so that it is possible to realize a display device which can be reduced in cost, thinned and lightened, and has high brightness, uniformity, high contrast and good display quality. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a conceptual top view showing an optical path in a display panel of light emitted from a light source of a lighting unit to a side surface of a display panel;
(A) is a diagram in which an illuminating unit is arranged on the side of the display panel in a direction parallel to the scanning electrodes of the display panel, and (b) is an illuminating unit arranged on the side of the display panel in a direction orthogonal to the scanning electrodes of the display panel. FIG.

FIG. 2 is a conceptual sectional view showing optical characteristics of a liquid crystal panel which is a display panel of the display device according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view of a main part showing a schematic configuration of the display device of the first embodiment.

FIG. 4 is a sectional view of a main part showing a schematic configuration of a display device according to a second embodiment.

FIG. 5 is a cross-sectional view of a main part showing a schematic configuration of a display device according to a third embodiment.

6 is a cross-sectional view of a main part showing a schematic configuration of a display device of FIG. 5 provided with a color filter.

FIG. 7 is a sectional view of a main part showing a schematic configuration of a display device according to a fourth embodiment.

FIG. 8 is a top view of the lower frame and lower substrate of the display device of the fourth embodiment of FIG. 7;

FIG. 9 is a perspective view of a main part showing a schematic configuration of a conventional display device, where (a) is a perspective view of the main part when no voltage is applied, and (b) is a perspective view of the main part when a voltage is applied.

FIG. 10 is a conceptual diagram for explaining an alignment principle of a liquid crystal panel of a conventional transmission type liquid crystal display.

FIGS. 11A and 11B are perspective views of main parts showing a schematic configuration of a conventional TN type liquid crystal display element, in which FIG. 11A is a main part perspective view of a simple matrix type liquid crystal display element, and FIG. It is a principal part perspective view.

[Explanation of symbols]

 1, 1a, 1b, 1c Upper substrate 2, 4 Electrode 3, 3 'Liquid crystal layer 5, 5a, 5b, 5c, Lower substrate 6 Fluorescent tube 6' Illumination unit 7 Lamp reflector 8 Color filter 14 Colored substrate

Claims (7)

[Claims] A plurality of scanning electrodes are disposed on one substrate surface between a pair of substrates on which a plurality of scanning electrodes are disposed and one or more information electrodes are disposed on an opposing substrate surface, or on one substrate surface. A display panel in which a dimming layer made of a liquid crystal material or the like whose transparent state and transmissive state are controlled by an applied voltage is sandwiched between a pair of substrates on which one or more information electrodes are arranged; A lighting unit disposed on a side surface in a direction perpendicular to the scanning electrode side, the lighting unit including a light source, and light from the lighting unit is incident on a side surface of the display panel to guide a substrate forming the display panel. It is characterized by having. 2. The display device according to claim 1, wherein the light modulating layer is made of a liquid crystal material having optical anisotropy such as a polymer dispersed liquid crystal material or a smectic liquid crystal material. 3. The display device according to claim 2, wherein the dimming layer is made of a liquid crystal material mixed with a dichroic dye. 4. The display device according to claim 1, wherein a reflection mechanism is provided on a side surface of the substrate forming the display panel where the illumination unit is not arranged. 5. A method according to claim 1, wherein the lower substrate on the opposite side of the display surface forming the display panel is a transparent substrate, and at least one surface of the lower substrate is colored, or a colored body is arranged on the back surface of the lower substrate. 5. One of claims 1 to 4, characterized in that
The display device according to item. 6. The display device according to claim 1, wherein the lower substrate forming the display panel also serves as a frame. 7. The method for driving a display device according to claim 1, wherein a selection voltage is applied to a scan electrode selected from among the scan electrodes, and the display device is driven by the selected voltage. A voltage for selectively setting the dimming layer to a transparent state or an opaque state by a potential difference is applied to the information electrode, and the scanning electrode that is not selected among the scanning electrodes is independent of the voltage applied to the information electrode. A method for driving a display device, comprising applying a voltage to make a light control layer transparent.