Display device

According to an aspect, a display device includes: a first translucent substrate; a second translucent substrate facing the first translucent substrate; a liquid crystal layer including polymer dispersed liquid crystal sealed between the first and second translucent substrates; at least one light emitter facing at least one of side surfaces of the first and the second translucent substrates; and a display controller. The display controller includes: an external light analyzer setting, in accordance with a received signal of external light information, a second color gamut different from a first color gamut displayable when the external light is not present; and a signal adjuster converting in color a first pixel input signal into a second pixel input signal that reduces a color shift of a second reproduced color in the second color gamut from a first reproduced color in the first color gamut in accordance with the first pixel input signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from Japanese Application No. 2017-095987, filed on May 12, 2017, the contents of which are incorporated by reference herein in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a display device.

2. Description of the Related Art

Japanese Patent Application Laid-open Publication No. 2016-085452 describes a display device including a light modulation layer and a light source. The light modulation layer is disposed between a pair of transparent substrates and includes a plurality of light modulation devices that have predetermined refractive index anisotropy and that are different in responsiveness to an electric field generated by electrodes provided on the transparent substrates. The light source emits light of a predetermined color into the light modulation layer from a side surface of the light modulation layer. The light modulation layer transmits the incident light received from the light source when the electric field is not generated, and scatters the incident light and emits the scattered light to the transparent substrates when the electric field is generated.

SUMMARY

According to an aspect, a display device includes: a first translucent substrate; a second translucent substrate facing the first translucent substrate; a liquid crystal layer including polymer dispersed liquid crystal sealed between the first translucent substrate and the second translucent substrate; at least one light emitter facing at least one of a side surface of the first translucent substrate or a side surface of the second translucent substrate; and a display controller including: an external light analyzer configured to set, in accordance with a received signal of external light information, a second color gamut different from a first color gamut displayable when the external light is not present; and a signal adjuster configured to convert in color a first pixel input signal into a second pixel input signal that reduces a color shift of a second reproduced color reproduced in the second color gamut from a first reproduced color reproduced in the first color gamut in accordance with the first pixel input signal.

According to another aspect, a display device includes: a first translucent substrate; a second translucent substrate facing the first translucent substrate; a liquid crystal layer including polymer dispersed liquid crystal sealed between the first translucent substrate and the second translucent substrate; at least one light emitter facing at least one of a side surface of the first translucent substrate or a side surface of the second translucent substrate; a display controller including: an external light analyzer configured to set, in accordance with a received signal of external light information, a second color gamut different from a first color gamut displayable when the external light is not present; and a signal adjuster configured to convert in color a first pixel input signal into a second pixel input signal that reduces a color shift of a second reproduced color reproduced in the second color gamut from a first reproduced color reproduced in the first color gamut in accordance with the first pixel input signal; and a first electrode and a second electrode interposing the liquid crystal layer therebetween. The light emitter is configured to sequentially emit light of a first color, light of a second color, and light of a third color based on a light emitter control value using a field-sequential system. The display controller is configured to: compare a gradation value of the first color, a gradation value of the second color, and a gradation value of the third color in the first pixel input signal with a gradation value of the first color, a gradation value of the second color, and a gradation value of the third color in the second pixel input signal on a color-by-color basis, and calculate, based on a higher gradation value of each of the colors, a gradation value of the first color, a gradation value of the second color, and a gradation value of the third color for a third pixel input signal; sequentially apply a voltage to the first electrode according to the gradation value of the first color, the gradation value of the second color, and the gradation value of the third color of the third pixel input signal; and set the light emitter control value for a color having the same gradation value as that of the first pixel input signal among the gradation value of the first color, the gradation value of the second color, and the gradation value of the third color of the third pixel input signal to a value lower than the light emitter control value for a color having the same gradation value as that of the second pixel input signal among the gradation value of the first color, the gradation value of the second color, and the gradation value of the third color of the third pixel input signal.

DETAILED DESCRIPTION

Exemplary aspects (embodiments) according to the present disclosure are described below in greater detail with reference to the accompanying drawings. The contents described in the embodiments are not intended to limit the present disclosure. Components described below include components easily conceivable by those skilled in the art and components substantially identical therewith. Furthermore, the components described below can be appropriately combined. The disclosure is given by way of example only, and various changes made without departing from the spirit of the disclosure and easily conceivable by those skilled in the art are naturally included in the scope of the invention. The drawings may possibly illustrate the width, the thickness, the shape, and the like of each unit more schematically than the actual aspect to simplify the explanation. These elements, however, are given by way of example only and are not intended to limit interpretation of the disclosure. In the specification and the figures, components similar to those previously described with reference to a preceding figure are denoted by like reference numerals, and detailed explanation thereof will be appropriately omitted. In this disclosure, when an element A is described as being “on” another element B, the element A can be directly on the other element B, or there can be one or more elements between the element A and the other element B.

FIG. 1is a perspective view illustrating an example of a display device according to the present embodiment.FIG. 2is a block diagram illustrating the display device ofFIG. 1.FIG. 3is a timing diagram for explaining timing of light emission by a light source in a field-sequential system.

As illustrated inFIG. 1, a display device1includes a display panel2, a side light source3, a drive circuit4constituting a part of a display controller5(refer toFIG. 2) to be described later, and an external light setter61. A PX direction denotes one direction of the display panel2. A PY direction denotes a direction orthogonal to the PX direction. A PZ direction denotes a direction orthogonal to a PX-PY plane.

The display panel2includes a first translucent substrate10, a second translucent substrate20, and a liquid crystal layer50(refer toFIG. 5). The second translucent substrate20faces a surface of the first translucent substrate10in a direction orthogonal thereto (in the PZ direction inFIG. 1). Polymer dispersed liquid crystal (to be described later) is sealed in the liquid crystal layer50(refer toFIG. 5) with the first translucent substrate10, the second translucent substrate20, and a sealing part19.

As illustrated inFIG. 1, the inside of the sealing part19in the display panel2serves as a display region. A plurality of pixels Pix are arranged in a matrix in the display region. In the present disclosure, a row refers to a pixel row including m pixels Pix arranged in one direction, and a column refers to a pixel column including n pixels Pix arranged in a direction orthogonal to the direction in which the rows are arranged. The values of m and n are determined according to a display resolution in the vertical direction and a display resolution in the horizontal direction. A plurality of scanning lines12are arranged row by row, and a plurality of signal lines13are arranged column by column.

The side light source3includes a light emitter31. As illustrated inFIG. 2, a light source controller32, a light source substrate33provided with the light emitter31and the light source controller32, and the drive circuit4constitute the display controller5. The light source substrate33is a flexible substrate, and serves also as wiring for electrically coupling the light source controller32to the drive circuit4(refer toFIG. 2). The light emitter31is electrically coupled to the light source controller32through the wiring in the light source substrate33.

The external light setter61is, for example, a visible light sensor. The visible light sensor detects external light69from an external light source Q, and generates information on tristimulus values (X,Y,Z) obtained by spectrally splitting the external light69according to the wavelength thereof as a signal ELV of the external light information. The external light setter61transmits the generated signal ELV of the external light information to the drive circuit4. The external light setter61is fixed to a surface of the first translucent substrate10. The external light setter61may be fixed to any positions as long as it can detect the external light69around the display panel2.

The external light setter61is not limited to the visible light sensor, but may be, for example, a setting switch for the external light. The setting switch for the external light generates the signal ELV of the external light information based on a set value of the external light information set in advance by a viewer according to visible light of the external light69. For example, the setting switch for the external light has predetermined external light tristimulus values (X′,Y′,Z′) serving as the external light information for each of environmental modes, such as a sunlight clear sky mode (first environment mode), a sunlight cloudy sky mode (second environment mode), an indoor use mode (third environment mode), and a night-time use mode (fourth environment mode). The external light setter61transmits the generated signal ELV of the external light information to the drive circuit4. If the external light setter61is the setting switch for the external light, the setting switch for the external light may be fixed at any positions as longs as it can transmit the signal ELV of the external light information to the drive circuit4.

As illustrated inFIG. 1, the drive circuit4is fixed to the surface of the first translucent substrate10. As illustrated inFIG. 2, the drive circuit4includes an analyzer41, a pixel controller42, a gate driver43, a source driver44, and a common potential driver45. The first translucent substrate10has an area larger than that of the second translucent substrate20in the X-Y plane, and the drive circuit4is provided on an overhanging portion of the first translucent substrate10exposed from the second translucent substrate20.

The analyzer41receives an input signal (e.g., a red-green-blue (RGB) signal) VS from an image output portion91of an external higher-level controller9through a flexible substrate92.

The analyzer41includes an input signal analyzer411, an external light analyzer412, a storage413, and a signal adjuster414. The input signal analyzer411generates a first pixel input signal VCS and a light source control signal LCS in accordance with an input signal VS input from the outside. The light source control signal LCS is a signal including information on a light quantity of the light emitter31set according to, for example, input gradation values given to all the pixels Pix. For example, the light quantity of the light emitter31is set smaller when a darker image is displayed, and set larger when a brighter image is displayed.

The first pixel input signal VCS is a signal for determining a gradation value to be given to each of the pixels Pix of the display panel2in accordance with the input signal VS. In other words, the first pixel input signal VCS is a signal including gradation information on the gradation value of each of the pixels Pix. The pixel controller42sets an output gradation value by performing correction processing, such as gamma correction and expansion processing, on each of the input gradation values of the first pixel input signal VCS.

The external light analyzer412receives the signal ELV of the external light information from the external light setter61described above. The external light analyzer412generates an adjustment signal LAS according to the signal ELV of the external light information based on a look-up table stored in the storage413. The external light analyzer412sets a second color gamut Cg2(refer toFIG. 14) to be described later, and then generates the adjustment signal LAS including information on a color conversion matrix M (to be described later) according to the second color gamut Cg2.

In a first control mode, the signal adjuster414generates a light source control signal LCSA directly from the light source control signal LCS without adjusting it using the adjustment signal LAS, and transmits the light source control signal LCSA to the light source controller32. The signal adjuster414then transmits a second pixel input signal VCSA generated from the first pixel input signal VCS to the pixel controller42. In a second control mode, the signal adjuster414generates the second pixel input signal VCSA from the first pixel input signal VCS according to the adjustment signal LAS, and transmits the second pixel input signal VCSA to the pixel controller42. The signal adjuster414then generates the light source control signal LCSA from the light source control signal LCS according to the adjustment signal LAS, and transmits the light source control signal LCSA to the light source controller32. The first control mode and the second control mode are switched, for example, by a control signal from the higher-level controller9. The signal adjuster414may operate only in the first control mode, or only in the second control mode.

The pixel controller42generates a horizontal drive signal HDS and a vertical drive signal VDS in accordance with the second pixel input signal VCS. In the present embodiment, since the display device1is driven by the field-sequential system, the horizontal drive signal HDS and the vertical drive signal VDS are generated for each color emittable by the light emitter31.

The gate driver43sequentially selects the scanning lines12of the display panel2in accordance with the horizontal drive signal HDS during one vertical scanning period. The scanning lines12can be selected in any order.

The source driver44supplies a gradation signal according to the output gradation value of each of the pixels Pix to corresponding one of the signal lines13of the display panel2in accordance with the vertical drive signal VDS during one horizontal scanning period.

In the present embodiment, the display panel2is an active-matrix panel. For this reason, the display panel2includes the signal (source) lines13extending in the PY direction and the scanning (gate) lines12extending in the PX direction in a plan view, and includes switching elements Tr at intersections between the signal lines13and the scanning lines12.

A thin-film transistor is used as each of the switching elements Tr. A bottom-gate transistor or a top-gate transistor may be used as an example of the thin-film transistor. Although a single-gate thin film transistor is exemplified as the switching element Tr, the switching element Tr may be a double-gate transistor. One of the source electrode and the drain electrode of the switching element Tr is coupled to each of the signal lines13, and the gate electrode of the switching element Tr is coupled to each of the scanning lines12. The other of the source electrode and the drain electrode is coupled to one end of a liquid crystal capacitor LC. The liquid crystal capacitor LC is coupled at one end thereof to the switching element Tr through a pixel electrode16, and coupled at the other end thereof to a common potential COM through a common electrode22. The common potential COM is supplied from the common potential driver45.

The light emitter31includes a light emitter34R of a first color (e.g., red), a light emitter34G of a second color (e.g., green), and a light emitter34B of a third color (e.g., blue). The light source controller32controls the light emitter34R of the first color, the light emitter34G of the second color, and the light emitter34B of the third color to emit light in a time-division manner in accordance with the light source control signal LCSA. In this manner, the light emitter34R of the first color, the light emitter34G of the second color, and the light emitter34B of the third color are driven by the field-sequential system.

As illustrated inFIG. 3, during a first sub-frame (first predetermined time) RON, the light emitter34R of the first color emits light, and the pixels Pix selected during one vertical scanning period GateScan scatter light to perform display. At this time, on the entire display panel2, if the above-described gradation signal according to the output gradation value of each of the pixels Pix selected during this vertical scanning period GateScan is supplied to corresponding one of the signal lines13, only the first color is lit up.

Subsequently, during a second sub-frame (second predetermined time) GON, the light emitter34G of the second color emits light, and the pixels Pix selected during one vertical scanning period GateScan scatter light to perform display. At this time, on the entire display panel2, if the above-described gradation signal according to the output gradation value of each of the pixels Pix selected during this vertical scanning period GateScan is supplied to corresponding one of the signal lines13, only the second color is lit up.

Further, during a third sub-frame (third predetermined time) BON, the light emitter34B of the third color emits light, and the pixels Pix selected during one vertical scanning period GateScan scatter light to perform display. At this time, on the entire display panel2, if the above-described gradation signal according to the output gradation value of each of the pixels Pix selected during this vertical scanning period GateScan is supplied to corresponding one of the signal lines13, only the third color is lit up.

The eyes of a human have a limited temporal resolution, and see an afterimage. Thus, the eyes of a human recognize a synthesized image of three colors in a period of one frame (1F). The field-sequential system requires no color filter, and suppresses an absorption loss in color filters, which can achieve higher transmittance. In a color filter system, one pixel is made of sub-pixels obtained by dividing each of the pixels Pix into sub-pixels of the first color, the second color, and the third color. On the other hand, the field sequential system does not require such division into sub-pixels, and thus can easily increase the resolution.

FIG. 4is a diagram for explaining a relation between a voltage applied to the pixel electrode and a scattering state of the pixel.FIG. 5is a sectional view illustrating an exemplary section of the display device ofFIG. 1.FIG. 6is a plan view illustrating a plane of the display device ofFIG. 1.FIG. 5illustrates a V-V′ section ofFIG. 6.FIG. 7is an enlarged sectional view obtained by enlarging the liquid crystal layer portion ofFIG. 5.FIG. 8is a sectional view for explaining a non-scattering state in the liquid crystal layer.FIG. 9is a sectional view for explaining the scattering state in the liquid crystal layer.

If the gradation signal according to the output gradation value of each of the pixels Pix selected during one vertical scanning period GateScan is supplied to each of the above-described signal lines13, the voltage applied to the pixel electrode16changes with the gradation signal. The change in the voltage applied to the pixel electrode16changes the voltage between the pixel electrode16and the common electrode22. The scattering state of the liquid crystal layer50for each of the pixels Pix is controlled according to the voltage applied to the pixel electrode16, and the scattering rate in the pixel Pix changes, as illustrated inFIG. 4.

As illustrated inFIGS. 5 and 6, the first translucent substrate10has a first principal surface10A, a second principal surface10B, a first side surface10C, a second side surface10D, a third side surface10E, and a fourth side surface10F. The first principal surface10A and the second principal surface10B are planes parallel to each other. The first side surface10C and the second side surface10D are planes parallel to each other. The third side surface10E and the fourth side surface1OF are planes parallel to each other.

As illustrated inFIGS. 5 and 6, the second translucent substrate20has a first principal surface20A, a second principal surface20B, a first side surface20C, a second side surface20D, a third side surface20E, and a fourth side surface20F. The first principal surface20A and the second principal surface20B are planes parallel to each other. The first side surface20C and the second side surface20D are planes parallel to each other. The third side surface20E and the fourth side surface20F are planes parallel to each other.

As illustrated inFIGS. 5 and 6, the light emitter31faces the first side surface20C of the second translucent substrate20. As illustrated inFIG. 5, the light emitter31emits light-source light L to the first side surface20C of the second translucent substrate20. The first side surface20C of the second translucent substrate20facing the light emitter31serves as a light incident surface. A gap G is provided between the light emitter31and the light incident surface. The gap G forms an air layer.

As illustrated inFIG. 5, the light-source light L emitted from the light emitter31propagates in a direction away from the first side surface20C while being reflected by the first principal surface10A of the first translucent substrate10and the first principal surface20A of the second translucent substrate20. When the light-source light L travels from the first principal surface10A of the first translucent substrate10or the first principal surface20A of the second translucent substrate20to the outside, the light-source light L enters a medium having a lower refractive index from a medium having a higher refractive index. Hence, if the incident angle of the light-source light L incident on the first principal surface10A of the first translucent substrate10or the first principal surface20A of the second translucent substrate20is larger than a critical angle, the light-source light L is fully reflected by the first principal surface10A of the first translucent substrate10or the first principal surface20A of the second translucent substrate20.

As illustrated inFIG. 5, the light-source light L that has propagated through the inside of the first translucent substrate10and that of the second translucent substrate20is scattered by any of the pixels Pix including liquid crystal in the scattering state, and the incident angle of the scattered light becomes an angle smaller than the critical angle. Thus, emission light68is emitted outward from the first principal surface20A of the second translucent substrate20, and emission light68A is emitted outward from the first principal surface10A of the first translucent substrate10or the first principal surface20A of the second translucent substrate20. The emission light68emitted outward from the first principal surface20A of the second translucent substrate20or the emission light68A emitted outward from the first principal surface10A of the first translucent substrate10is viewed by the viewer. In the present disclosure, a value representing a level of luminance of the emission light68or the emission light68A in the pixel Pix is called an emission luminance gradation value. The following describes the polymer dispersed liquid crystal in the scattering state and the polymer dispersed liquid crystal in the non-scattering state, usingFIGS. 7 to 9.

As illustrated inFIG. 7, the first translucent substrate10is provided with a first orientation film55, and the second translucent substrate20is provided with a second orientation film56. The first and the second orientation films55and56are, for example, vertical orientation films.

A solution obtained by dispersing liquid crystal molecules in monomers is filled between the first translucent substrate10and the second translucent substrate20. Subsequently, in a state where the monomers and the liquid crystal molecules are oriented by the first and the second orientation films55and56, the monomers are polymerized by ultraviolet rays or heat to form a bulk51. This process forms the liquid crystal layer50including the reverse-mode polymer dispersed liquid crystal in which the liquid crystal molecules are dispersed in gaps of a polymer network formed in a mesh shape.

In this manner, the liquid crystal layer50includes the bulk51formed of the polymers and a plurality of fine particles52dispersed in the bulk51. The fine particles52include the liquid crystal. Both the bulk51and the fine particles52have optical anisotropy.

The orientation of the liquid crystal included in the fine particles52is controlled by a voltage difference between the pixel electrode16and the common electrode22. The orientation of the liquid crystal is changed by the voltage applied to the pixel electrode16. The degree of scattering of light passing through the pixel Pix changes in accordance with the change in the orientation of the liquid crystal.

For example, as illustrated inFIG. 8, the direction of an optical axis Ax1of the bulk51is the same as the direction of an optical axis Ax2of the fine particles52when no voltage is applied between the pixel electrode16and the common electrode22. The optical axis Ax2of the fine particles52is parallel to the PZ direction of the liquid crystal layer50. The optical axis Ax1of the bulk51is parallel to the PZ direction of the liquid crystal layer50regardless of whether the voltage is applied.

An ordinary-ray refractive index of the bulk51and that of the fine particles52are equal to each other. When no voltage is applied between the pixel electrode16and the common electrode22, the difference of refractive index between the bulk51and the fine particles52is zero in all directions. The liquid crystal layer50becomes the non-scattering state of not scattering the light-source light L. The light-source light L propagates in a direction away from the light emitter31while being reflected by the first principal surface10A of the first translucent substrate10and the first principal surface20A of the second translucent substrate20. When the liquid crystal layer50is in the non-scattering state of not scattering the light-source light L, a background on the first principal surface20A side of the second translucent substrate20is visible from the first principal surface10A of the first translucent substrate10, and a background on the first principal surface10A side of the first translucent substrate10is visible from the first principal surface20A of the second translucent substrate20.

As illustrated inFIG. 9, the optical axis Ax2of the fine particle52is inclined by an electric field generated between the pixel electrode16and the common electrode22to which the voltage is applied. Since the optical axis Ax1of the bulk51remains unchanged by the electric field, the direction of the optical axis Ax1of the bulk51differs from the direction of the optical axis Ax2of the fine particles52. The light-source light L is scattered in the pixel Pix including the pixel electrode16to which the voltage is applied. As described above, the viewer views a part of the scattered light-source light L emitted outward from the first principal surface10A of the first translucent substrate10or the first principal surface20A of the second translucent substrate20.

In the pixel Pix including the pixel electrode16to which no voltage is applied, the background on the first principal surface20A side of the second translucent substrate20is visible from the first principal surface10A of the first translucent substrate10, and the background on the first principal surface10A side of the first translucent substrate10is visible from the first principal surface20A of the second translucent substrate20. In the display device1of the present embodiment, when the input signal VS is entered from the image output portion91, the voltage is applied to the pixel electrode16of the pixel Pix displaying an image, and the image in accordance with the second pixel input signal VCSA becomes visible together with the background.

The image displayed by the light-source light L, which is scattered in the pixel Pix including the pixel electrode16to which the voltage is applied and is emitted outward, superimposes the background to be displayed. In other words, the display device1of the present embodiment displays the image superimposing the background by combining the emission light68or the emission light68A with the background.

FIG. 10is a plan view illustrating the pixel.FIG. 11is a sectional view along XI-XI′ inFIG. 10. As illustrated inFIGS. 1, 2, and 10, the first translucent substrate10is provided with the signal lines13and the scanning lines12so as to form a grid in the plan view. A region surrounded by the adjacent scanning lines12and the adjacent signal lines13corresponds to the pixel Pix. The pixel Pix is provided with the pixel electrode16and the switching element Tr. In the present embodiment, the switching element Tr is a bottom-gate thin film transistor. The switching element Tr includes a semiconductor layer15overlapping, in the plan view, with a gate electrode12G electrically coupled to corresponding one of the scanning lines12.

The scanning line12is wiring made of a metal such as molybdenum (Mo) and aluminum (Al), a layered body of the aforementioned metal, or an alloy of the aforementioned metal. The signal line13is wiring made of a metal, such as aluminum, or an alloy.

The semiconductor layer15is provided so as not to protrude from the gate electrode12G in the plan view. This configuration causes the light-source light L traveling from the gate electrode12G toward the semiconductor layer15to be reflected, and is less likely to cause leakage of light in the semiconductor layer15

As illustrated inFIG. 10, a source electrode13S electrically coupled to corresponding one of the signal lines13overlaps with one end portion of the semiconductor layer15in the plan view.

As illustrated inFIG. 10, a drain electrode14D is provided in a position adjacent to the source electrode13S across a central portion of the semiconductor layer15in the plan view. The drain electrode14D overlaps with the other end portion of the semiconductor layer15in the plan view. A portion not overlapping with either of the source electrode13S or the drain electrode14D serves as a channel of the switching element Tr. As illustrated in FIG.

11, conductive wiring14coupled to the drain electrode14D is electrically coupled to the pixel electrode16at a through-hole SH.

As illustrated inFIG. 11, the first translucent substrate10includes a first base member11made of, for example, glass. The first base member11may be made of a resin, such as polyethylene terephthalate, as long as having translucency. A first insulating layer17ais provided on the first base member11, and the scanning line12and the gate electrode12G are provided on the first insulating layer17a.A second insulating layer17bis provided to cover the scanning line12. The first insulating layer17aand the second insulating layer17bare each made of, for example, a transparent inorganic insulating member, such as a silicon nitride member.

The semiconductor layer15is stacked on the second insulating layer17b.The semiconductor layer15is made of, for example, amorphous silicon, but may be made of polysilicon or an oxide semiconductor.

The source electrode13S that covers a part of the semiconductor layer15, the signal line13, the drain electrode14D that covers a part of the semiconductor layer15, and the conductive wiring14are provided on the second insulating layer17b.The drain electrode14D is made of the same material as that of the signal line13. A third insulating layer17cis provided on the semiconductor layer15, the signal lines13, and the drain electrode14D. The third insulating layer17cis made of, for example, a transparent inorganic insulating member, such as a silicon nitride member.

The pixel electrode16is provided on the third insulating layer17c.The pixel electrode16is made of a translucent conductive member, such as an indium tin oxide (ITO) member. The pixel electrode16is electrically coupled to the conductive wiring14and the drain electrode14D through contact holes provided in the third insulating layer17c.The first orientation film55is provided on the pixel electrode16.

The second translucent substrate20includes a second base member21made of, for example, glass. The second base member21may be made of a resin, such as polyethylene terephthalate, as long as having translucency. The second base member21is provided with the common electrode22. The common electrode22is made of a translucent conductive member, such as an ITO member. The second orientation film56is provided on a surface of the common electrode22.

FIG. 12is a diagram for explaining the incident light from the light emitter. When light from the light emitter31enters the first side surface20C of the second translucent substrate20at an angle θ0, the light enters the first principal surface20A of the second translucent substrate20at an angle i1. If the angle i1is larger than the critical angle, the light-source light L is fully reflected at an angle i2by the first principal surface20A of the second translucent substrate20, and propagates through the inside of the second translucent substrate20. Since the gap G is provided between the light emitter31and the first side surface20C (light incident surface) as illustrated inFIG. 12, light-source light LN at an angle θN by which the angle i1becomes smaller than the critical angle is not guided to the first side surface20C of the second translucent substrate20.

FIG. 13is a diagram for explaining the influence of external light on display light in the pixel.FIG. 14is a diagram for explaining the influence of the external light on color gamuts of the display panel in an xy chromaticity diagram. As illustrated inFIG. 13, when the external light69from the external light source Q enters the display panel2, the external light69in addition to the emission light68is emitted as the display light. As a result, as illustrated inFIG. 13, the viewer views the emission light68having the tristimulus values (X,Y,Z) emitted by the display panel2and the light having the external light tristimulus values (X′,Y′,Z′) transmitted through the display panel2.

In the state where the external light is incident on the display panel2, the external light that has entered the display panel2is scattered in the pixels Pix according to the applied voltage, and is also emitted as the emission light68. In the state where the external light is incident on the display panel2, the light-source light L and the external light are scattered, and the emission light68is viewed from the outside of the display panel2. As a result, the image displayed on the display panel2has a mixed color obtained by mixing an input color of the image in accordance with the second pixel input signal VCS with the external light color. Consequently, the coordinates of a color displayed in a first color gamut Cg1may be shifted to coordinates of a color displayed in the second color gamut Cg2in the xy chromaticity diagram even if the image is displayed by the same input signal.

As illustrated inFIG. 14, a region of the second color gamut Cg2that is displayable when the external light is present is smaller than a region of the first color gamut Cg1that is displayable when the external light is not present.

FIG. 15is a diagram for explaining the tristimulus values viewed by the viewer in the field-sequential system. In the field-sequential system, the tristimulus values in the color gamut emitted by the display panel2are represented as a table TCG1inFIG. 15. When the external light is present, the external light is added in each of the first sub-frame RON, the second sub-frame GON, and the third sub-frame BON illustrated inFIG. 3. As a result, when the external light is present, the tristimulus values in a color gamut viewed by the viewer are represented as a table TCG2inFIG. 15.

FIG. 16is a diagram for explaining the color gamuts ofFIG. 14.FIG. 17is another diagram for explaining the color gamuts ofFIG. 14. The tristimulus values in the color gamut emitted by the display panel2are represented as the table TCG1inFIG. 16. The tristimulus values of the external light are represented as a table TLD inFIG. 16. The tristimulus values in the color gamut viewed by the viewer are represented as the table TCG2inFIG. 16.

The table TCG1inFIG. 16is represented as a table Tcg1in chromaticity coordinates. The table Tcg1represents the chromaticity coordinates (x,y) in the first color gamut Cg1. The table TCG2inFIG. 16is represented as a table Tcg2in the chromaticity coordinates. The table Tcg2represents the chromaticity coordinates (x,y) in the second color gamut Cg2.

FIG. 18is a diagram for explaining color conversion matrices for converting in color the first pixel input signal into the second pixel input signal in the present embodiment. As illustrated inFIG. 18, color conversion matrices M, MA, and MBare conversion matrices of three rows and three columns.

The color conversion matrix MArepresented by Expression (1) below is a conversion matrix for converting the RGB signal into the tristimulus values (X,Y,Z) based on the description of the table TCG1inFIG. 16.

The color conversion matrix MDis obtained based on the table TCG2inFIG. 16, as given in Expression (2) below. The color conversion matrix MBis a conversion matrix for converting the RGB signal into tristimulus values (X+X′,Y+Y′,Z+Z′) in the second color gamut Cg2.

The color conversion matrix M is calculated from the color conversion matrix MAand the inverse matrix of the color conversion matrix MD, as given in Expression (3) below.

A first input color [Rin,Gin,Bin] entered as the input signal is converted into a second input color [Rout,Gout,Bout] by the color conversion matrix M, as given in Expression (4) below. When the second input color [Rout,Gout,Bout] is displayed on the display panel2in the color gamut viewed by the viewer when the external light is present, the present embodiment prevents the second input color [Rout,Gout,Bout] from shifting from the first input color [Rin,Gin,Bin].

In the present embodiment, the matrix of Expression (3) is used as the color conversion matrix M in Expression (4).

FIG. 19is a flowchart for the color conversion processing of the present embodiment. The signal adjuster414illustrated inFIG. 2receives an RGB signal [Rin,Gin,Bin] as the first pixel input signal VCS (Step S11).

Then, the RGB signal [Rin,Gin,Bin] is gamma-converted into a linear RGB signal (Step S12). The linear RGB signal is subjected to the color conversion (color gamut conversion) by the color conversion matrix M described above (Step S13).

If data components obtained by the color conversion include a value smaller than 0 or greater than 1 (Yes at Step S14), the signal adjuster414performs processing of out-of-gamut correction (Step S15). In the out-of-gamut correction (Step S15), a value or values smaller than 0 among the data components obtained by the color conversion is/are set to 0, and a value or values greater than 1 among the data components obtained by the color conversion is/are set to 1. The data components after being subjected to the out-of-gamut correction (Step S15) are inversely gamma-converted (Step S16). An RGB signal [Rout,Gout,Bout] obtained by the inverse gamma conversion serves as the second pixel input signal VCSA (Step S17).

If the data components obtained by the color conversion do not include a value smaller than 0 or greater than 1 (No at Step S14), the signal adjuster414performs the inverse gamma conversion (Step S16). The RGB signal [Rout,Gout,Bout] obtained by the inverse gamma conversion serves as the second pixel input signal VCSA (Step S17).

First conversion example of pixel input signal FIG.20is a diagram for explaining a conversion example of the pixel input signal according to the present embodiment. As illustrated inFIG. 20, an RGB signal [157,188,64] serving as a signal of the first input color is entered as the first pixel input signal VCS (Step S11). Then, the RGB signal [157,188,64] is gamma-converted (Step S12) into a signal [0.34,0.50,0.05]. The signal [0.34,0.50,0.05] is subjected to the color gamut conversion using the color conversion matrix M as coefficients to be a signal [0.36,0.67,−0.20]. Since the data components include −0.20, which is smaller than 0 (Yes at Step S14), the out-of-gamut correction is performed to obtain a signal [0.36,0.67,0.00]. The signal [0.36,0.67,0.00] is inversely gamma-converted (Step S16) into an RGB signal [162,214,0], which serves as the second pixel input signal VCSA (Step S17).

Based on Expression (1) given above, the RGB signal [157,188,64] represents a first reproduced color d11in the xy chromaticity diagram illustrated inFIG. 14. The RGB signal [162,214,0] represents a second reproduced color d12in the xy chromaticity diagram illustrated inFIG. 14. According to the present embodiment, the second reproduced color d12can be reproduced at an outer border of the second color gamut Cg2even when the first reproduced color d11is outside the second color gamut Cg2. As a result, the display device1can improve the color reproducibility of the image displayed on the display panel2even under the influence of the external light.

Second Conversion Example of Pixel Input Signal

FIG. 21is a diagram for explaining another conversion example of the pixel input signal according to the present embodiment. As illustrated inFIG. 21, an RGB signal [133,128,177] serving as a signal of the first input color is entered as the first pixel input signal VCS (Step S11). Then, the RGB signal [133,128,177] is gamma-converted (Step S12) into a signal [0.23,0.22,0.44]. The signal [0.23,0.22,0.44] is subjected to the color gamut conversion using the color conversion matrix M as coefficients to be a signal [0.17,0.15,0.56]. Since the data components obtained by the color conversion do not include a value smaller than 0 or greater than 1 (No at Step S14), the signal [0.17,0.15,0.56] is inversely gamma-converted (Step S16) into an RGB signal [114,108,197], which serves as the second pixel input signal VCSA.

Based on Expression (1) given above, the RGB signal [133,128,177] represents a first reproduced color d13in the xy chromaticity diagram illustrated inFIG. 14. Based on Expression (2) given above, the RGB signal [114,108,197] represents a second reproduced color d14in the xy chromaticity diagram illustrated inFIG. 14. In this manner, the color shift is smaller between the first reproduced color d13and the second reproduced color d14in the xy chromaticity diagram illustrated inFIG. 14. Thus, the present embodiment prevents the color shift of the reproduced color even under the influence of the external light.

First Control Mode

The following describes an example in which the signal adjuster414operates in the first control mode.FIG. 22illustrates an example of gradation values of an RGB signal and light emission intensities of the light emitter in the period of one frame in one pixel. In the example illustrated inFIG. 22, each of the light emitter34R of the first color, the light emitter34G of the second color, and the light emitter34B of the third color is driven so as to emit light at the same light emission intensity of 100%.

The light emitter31sequentially emits the light from the light emitter34R of the first color, the light from the light emitter34G of the second color, and the light from the light emitter34B of the third color using the field-sequential system. The display controller5applies the voltage to the pixel electrode16according to the gradation value of each of the first color, the second color, and the third color in accordance with the second pixel input signal VCSA. The order of the light emission of the first color, the light emission of the second color, and the light emission of the third color may be any order as long as emission timing of each of the light of the first color, the light of the second color, and the light of the third color is synchronized with application timing of the voltage to the pixel electrode16according to the gradation value of each of the first, second, and third colors. The display controller5controls, for example, the amount of lighting of the light emitter31so as to emit the light of the first color, the light of the second color, and the light of the third color at the same light emission intensity.

When the RGB signal [133,128,177] of the first pixel input signal VCS is converted into the RGB signal [114,108,197] of the second pixel input signal VCSA, the display device1can reproduce the second reproduced color d14illustrated inFIG. 14.

As described above, the display device1includes the first translucent substrate10, the second translucent substrate20, the liquid crystal layer50, the light emitter31, and the display controller5. The light emitter31faces at least one of a side surface of the first translucent substrate10and a side surface of the second translucent substrate20. The display controller5includes the external light analyzer412and the signal adjuster414. The external light analyzer412sets, in accordance with the received signal ELV of the external light information, the second color gamut Cg2different from the first color gamut Cg1that is displayable when the external light is not present. The signal adjuster414converts in color the first pixel input signal VCS into the second pixel input signal VCSA that reduces the color shift of the second reproduced color d14reproduced in the second color gamut Cg2from the first reproduced color d13reproduced in the first color gamut Cg1in accordance with the first pixel input signal VCS.

This configuration allows the display device1to improve the color reproducibility of the image displayed on the display panel2even under the influence of the external light.

Second Control Mode

The following describes an example in which the signal adjuster414operates in the second control mode.FIG. 23is another flowchart for the color conversion processing of the present embodiment.FIG. 24illustrates another example of the gradation values of the RGB signal and the light emission intensities of the light emitter in the period of one frame in one pixel. Steps S21to S26inFIG. 26correspond to Steps S11to S16, respectively, inFIG. 19, and will therefore not be described in detail.

Also in the second control mode, the signal adjuster414performs the inverse gamma conversion at Step S26to obtain the RGB signal [Rout,Gout,Bout] (Step S27). The signal adjuster414compares the RGB signal [Rin,Gin,Bin] with the RGB signal [Rout,Gout,Bout]. The signal adjuster414combines gradation values among the gradation values of the RGB signal [Rout,Gout,Bout] that are higher than the respective gradation values of the RGB signal [Rin,Gin,Bin] with gradation values among the gradation values of the RGB signal [Rin,Gin,Bin] that are equal to or lower than the respective gradation values of the RGB signal [Rout,Gout,Bout] to calculate gradation values of an RGB signal of a third pixel input signal. In other words, the signal adjuster414compares the gradation values of the RGB signal [Rout,Gout,Bout] with the gradation values of the RGB signal [Rin,Gin,Bin] on a color-by-color basis, and selects a higher gradation value of each color to calculate a gradation value of corresponding one of the first, second, and third colors of the third pixel input signal (Step S28). For example, the RGB signal [Rin,Gin,Bin] is compared with the RGB signal [Rout,Gout,Bout], and if the relations hold as Rin>Rout, Gin>Gout, and Bin<Bout, the third pixel input signal is set to an RGB signal [Rin,Gin,Bout].

To explain the calculation using the second conversion example of the pixel input signal described above, the RGB signal [133,128,177] of the first pixel input signal VCS is converted into an RGB signal [133,128,197] of the second pixel input signal VCSA, as illustrated inFIG. 24.

In the case of the light emission intensity of blue serving as the third color illustrated inFIG. 24, if the gradation value [177] of the third color in the first pixel input signal VCS specifies that the light emitter31is to emit light at a light emission intensity of 100%, the gradation value [197] of the third color in the second pixel input signal VCSA specifies that the light emitter31is to emit light at the light emission intensity of 100%. That is, in the case of the third color, the light emitter control value of the light source control signal LCS is equal to the light emitter control value of the light source control signal LCSA. In the example illustrated inFIG. 24, the light emitter control value is the light emission intensity.

In the case of the light emission intensity of red serving as the first color illustrated inFIG. 24, if the gradation value [133] of the first color in the first pixel input signal VCS specifies that the light emitter31is to emit light at a light emission intensity of 100%, the gradation value [133] of the first color in the second pixel input signal VCSA specifies that the light emitter31is to emit light at a light emission intensity of 72%.

In the case of the light emission intensity of green serving as the second color illustrated inFIG. 24, if the gradation value [128] of the second color in the first pixel input signal VCS specifies that the light emitter31is to emit light at a light emission intensity of 100%, the gradation value [128] of the second color in the second pixel input signal VCSA specifies that the light emitter31is to emit light at a light emission intensity of 69%.

The ratios [72%,69%,100%] in the light emission intensities of the first, second, and third colors of the light emitter illustrated inFIG. 24are calculated such that the above-described second reproduced color d14can be reproduced when the display controller5sequentially applies the voltage to the pixel electrode16according to each of the gradation values of the RGB signal [133,128,197].

As described above, the signal adjuster414compares the gradation values of the RGB signal [Rout,Gout,Bout] with the gradation values of the RGB signal [Rin,Gin,Bin] on a color-by-color basis, and selects the higher gradation value of each color to calculate the gradation value of corresponding one of the first, second, and third colors of the third pixel input signal (Step S28). For example, the RGB signal [Rin,Gin,Bin] is compared with the RGB signal [Rout,Gout,Bout], and if the relations hold as Rin>Rout, Gin>Gout, and Bin<Bout, the third pixel input signal is set to the RGB signal [Rin,Gin,Bout]. For each of Rin and Gin among those of the RGB signal [Rin,Gin,Bout] of the third pixel input signal that are equal to those of the RGB signal [Rin,Gin,Bin] of the first pixel input signal, the display controller5sets the light emission intensity ratio to a value lower than the same light emission intensity ratio as that in the case where the display controller5sequentially applies the voltage to the pixel electrode16according to each of the gradation values of the RGB signal [Rin,Gin,Bin] of the first pixel input signal. For Bout equal to that of the RGB signal [Rout,Gout,Bout] of the second pixel input signal, the ratio in the light emission intensity of the light emitter serving as the light emitter control value is not changed from the same light emission intensity ratio as that in the case where the display controller5sequentially applies the voltage to the pixel electrode16according to each of the gradation values of the RGB signal [Rin,Gin,Bin] of the first pixel input signal. In this manner, if the display controller5sequentially applies the voltage to the pixel electrode16according to the RGB signal [Rin,Gin,Bout] of the third pixel input signal, the display controller5calculates the light emission intensities of the first, second, and third colors of the light emitter according to the RGB signal [Rin,Gin,Bout] of the third pixel input signal (Step S29).

As described above, in the second control mode, the signal adjuster414generates the RGB signal [133,128,197] of the second pixel input signal VCSA from the RGB signal [133,128,177] of the first pixel input signal VCS according to the adjustment signal LAS, and transmits the RGB signal [133,128,197] to the pixel controller42. The signal adjuster414then generates the light source control signal LCSA of the ratios [72%,69%,100%] in the light emission intensity of the light emitter from the light source control signal LCS according to the adjustment signal LAS, and transmits the light source control signal LCSA to the light source controller32.

As a result, the present embodiment prevents the color shift of the reproduced color even under the influence of the external light.

FIG. 25illustrates an example of the gradation values of the RGB signal and light emission PW duty ratios of the light emitter in the period of one frame in one pixel. The light emitter31can modulate light at a duty ratio of pulse width modulation (PWM). The light emitter control value may be the PWM duty ratio as illustrated inFIG. 25.

In the case of the light emission intensity of blue serving as the third color illustrated inFIG. 25, if the gradation value [177] of the third color in the first pixel input signal VCS specifies that the light emitter31is to emit light at a PWM duty ratio of 33%, the gradation value [197] of the third color in the second pixel input signal VCSA specifies that the light emitter31is to emit light at the PWM duty ratio of 33%. That is, in the case of the third color, the light emitter control value of the light source control signal LCS is equal to the light emitter control value of the light source control signal LCSA. In the example illustrated inFIG. 25, the light emitter control value is the PWM duty ratio.

In the case of the light emission intensity of red serving as the first color illustrated inFIG. 25, if the gradation value [133] of the first color in the first pixel input signal VCS specifies that the light emitter31is to emit light at a PWM duty ratio of 33%, the gradation value

of the first color in the second pixel input signal VCSA specifies that the light emitter31is to emit light at a PWM duty ratio of 24%.

In the case of the light emission intensity of green serving as the second color illustrated inFIG. 25, if the gradation value [128] of the second color in the first pixel input signal VCS specifies that the light emitter31is to emit light at a PWM duty ratio of 33%, the gradation value [128] of the second color in the second pixel input signal VCSA specifies that the light emitter31is to emit light at a PWM duty ratio of 23%.

The PWM duty ratios [24%,23%,33%] of the first, second, and third colors of the light emitter illustrated inFIG. 25are calculated such that the above-described second reproduced color d14can be reproduced when the display controller5sequentially applies the voltage to the pixel electrode16according to each of the gradation values of the RGB signal [133,128,197].

The signal adjuster414combines the gradation values among the gradation values of the RGB signal [Rout,Gout,Bout] that are higher than the respective gradation values of the RGB signal [Rin,Gin,Bin] with the gradation values among the gradation values of the RGB signal [Rin,Gin,Bin] that are equal to or lower than the respective gradation values of the RGB signal [Rout,Gout,Bout], to calculate the gradation values of the RGB signal of the third pixel input signal (Step S28). For example, the RGB signal [Rin,Gin,Bin] is compared with the RGB signal [Rout,Gout,Bout], and if the relations hold as Rin>Rout, Gin>Gout, and Bin<Bout, the third pixel input signal is set to the RGB signal [Rin,Gin,Bout]. For each of Rin and Gin among those of the RGB signal [Rin,Gin,Bout] of the third pixel input signal that are equal to those of the RGB signal [Rin,Gin,Bin] of the first pixel input signal, the display controller5sets the PWM duty ratio to a value lower than the same PWM duty ratio as that in the case where the display controller5sequentially applies the voltage to the pixel electrode16according to each of the gradation values of the RGB signal [Rin,Gin,Bin] of the first pixel input signal. For Bout equal to that of the RGB signal [Rout,Gout,Bout] of the second pixel input signal, the PWM duty ratio of the light emitter serving as the light emitter control value is not changed from the same PWM duty ratio as that in the case where the display controller5sequentially applies the voltage to the pixel electrode16according to each of the gradation values of the RGB signal [Rin,Gin,Bin] of the first pixel input signal. In this manner, if the display controller5sequentially applies the voltage to the pixel electrode16according to the RGB signal [Rin,Gin,Bout] of the third pixel input signal, the display controller5calculates the light emission intensities of the first, second, and third colors of the light emitter according to the RGB signal [Rin,Gin,Bout] of the third pixel input signal (Step S29).

As described above, in the second control mode, the signal adjuster414generates the RGB signal [133,128,197] of the second pixel input signal VCSA from the RGB signal [133,128,177] of the first pixel input signal VCS according to the adjustment signal LAS, and transmits the RGB signal [133,128,197] to the pixel controller42. The signal adjuster414then generates the light source control signal LCSA including the information on the PWM duty ratios [24%,23%,33%] of the first, second, and third colors of the light emitter from the light source control signal LCS according to the adjustment signal LAS, and transmits the light source control signal LCSA to the light source controller32.

As a result, the present embodiment prevents the color shift of the reproduced color even under the influence of the external light.

First Modification

FIG. 26is a plan view illustrating a plane of a display device according to a first modification of the embodiment.FIG. 27is a sectional view along XXVII-XXVII′ inFIG. 26. The same components as those described above in the present embodiment are denoted by the same reference numerals, and the description thereof will not be repeated. Since the section along V-V′ inFIG. 26is the same as that of the display device of the present embodiment illustrated inFIG. 5, the description thereof will not be repeated.

As illustrated inFIGS. 26 and 27, one of the light emitters31faces the fourth side surface20F of the second translucent substrate20. As illustrated inFIG. 27, the light emitter31emits the light-source light L to the fourth side surface20F of the second translucent substrate20. The fourth side surface20F of the second translucent substrate20facing the light emitter31serves as a light incident surface. The gap G is provided between the light emitter31and the light incident surface. The gap G forms an air layer.

As illustrated inFIG. 27, the light-source light L emitted from the light emitter31propagates in a direction away from the fourth side surface20F while being reflected by the first principal surface10A of the first translucent substrate10and the first principal surface20A of the second translucent substrate20.

The display device1according to the first modification of the present embodiment includes the first translucent substrate10, the second translucent substrate20, the liquid crystal layer50, and the light emitters31. One of the two light emitters31faces the first side surface20C of the second translucent substrate20and the other thereof faces the fourth side surface20F of the second translucent substrate20. This configuration increases the light quantity of in-plane light emitted from the two light emitters31and propagating in the display panel2. The configuration also increases uniformity of the in-plane light propagating in the display panel2. A region P1and a region P2illustrated inFIG. 6differ in distance from the light emitter31, and therefore differ in in-plane light quantity. In contrast, in the display device1according to the first modification of the present embodiment, the light propagates from two intersecting directions, thereby decreasing the difference in in-plane light quantity.

Second Modification

FIG. 28is a plan view illustrating a plane of a display device according to a second modification of the present embodiment.FIG. 29is a sectional view along XXIX-XXIX′ inFIG. 28.FIG. 30is a sectional view along XXX-XXX′ inFIG. 28. The same components as those described above in the present embodiment or the modification thereof are denoted by the same reference numerals, and the description thereof will not be repeated.

As illustrated inFIGS. 28 and 29, one of the light emitters31faces the second side surface20D of the second translucent substrate20. As illustrated inFIG. 29, the light emitter31emits the light-source light L to the second side surface20D of the second translucent substrate20. The second side surface20D of the second translucent substrate20facing the light emitter31serves as a light incident surface. The gap G is provided between the light emitter31and the light incident surface. The gap G forms an air layer.

As illustrated inFIG. 29, the light-source light L emitted from the light emitter31propagates in a direction away from the second side surface20D while being reflected by the first principal surface10A of the first translucent substrate10and the first principal surface20A of the second translucent substrate20.

As illustrated inFIGS. 28 and 30, the other of the light emitters31faces the third side surface20E of the second translucent substrate20. As illustrated inFIG. 30, the light emitter31emits the light-source light L to the third side surface20E of the second translucent substrate20. The third side surface20E of the second translucent substrate20facing the light emitter31serves as a light incident surface. The gap G is provided between the light emitter31and the light incident surface. The gap G forms an air layer.

As illustrated inFIG. 30, the light-source light L emitted from the light emitter31propagates in a direction away from the third side surface20E while being reflected by the first principal surface10A of the first translucent substrate10and the first principal surface20A of the second translucent substrate20.

The display device1according to the second modification of the present embodiment includes the first translucent substrate10, the second translucent substrate20, the liquid crystal layer50, and the light emitters31. One of the two light emitters31faces the second side surface20D of the second translucent substrate20, and the other thereof faces the third side surface20E of the second translucent substrate20. This configuration increases the light quantity of the in-plane light emitted from the two light emitters31and propagating in the display panel2. The configuration also increases uniformity of the in-plane light propagating in the display panel2. The region P1and the region P2illustrated inFIG. 6differ in distance from the light emitter31, and therefore differ in in-plane light quantity. In contrast, in the display device1according to the second modification of the present embodiment, the light propagates from two intersecting directions, thereby decreasing the difference in in-plane light quantity.

In the same manner as the present embodiment, the display device1according to the second modification of the present embodiment does not include a backlight device or a reflecting plate on the first principal surface10A side of the first translucent substrate10or on the first principal surface20A side of the second translucent substrate20. As a result, the background on the first principal surface20A side of the second translucent substrate20is visible from the first principal surface10A of the first translucent substrate10, and the background on the first principal surface10A side of the first translucent substrate10is visible from the first principal surface20A of the second translucent substrate20.

The preferred embodiment of the present disclosure has been described. However, the present disclosure is not limited by the embodiment. The content disclosed in the embodiment is merely an example, and various modifications can be made without departing from the gist of the present disclosure. Appropriate modifications made without departing from the gist of the present disclosure obviously belong to the technical scope of the present disclosure. All the technologies that can be appropriately designed, modified, and implemented by a person skilled in the art on the basis of the above-described disclosure belong to the technical scope of the present disclosure as long as the technologies include the gist of the present disclosure.

The display panel2may be, for example, a passive-matrix panel without a switching element. The passive-matrix panel includes first electrodes extending in the PX direction, second electrodes extending in the PY direction, in the plan view, and wiring electrically coupled to the first electrodes or the second electrodes. The first and second electrodes and the wiring are made of, for example, ITO. For example, the first translucent substrate10including the first electrodes and the second translucent substrate20including the second electrodes face each other across the liquid crystal layer50.

Although the example has been described in which the first and the second orientation films55and56are vertical orientation films, the first and the second orientation films55and56may be both horizontal orientation films. The first orientation film55and the second orientation film56only need to have a function to orient the monomers in a predetermined direction in polymerizing the monomers. This allows the monomers to become polymers oriented in the predetermined direction. When the first orientation film55and the second orientation film56are the horizontal orientation films, the direction of the optical axis Ax1of the bulk51and the direction of the optical axis Ax1of the fine particle52are the same, and are orthogonal to the PZ direction, in a state in which no voltage is applied between the pixel electrode16and the common electrode22. The direction orthogonal to the PZ direction corresponds to the PX direction or the PY direction along a side of the first translucent substrate10in the plan view.

The embodiment and the modifications include the following aspects.(1) A display device comprising:

a first translucent substrate;

a second translucent substrate facing the first translucent substrate;

a liquid crystal layer including polymer dispersed liquid crystal sealed between the first translucent substrate and the second translucent substrate;

at least one light emitter facing at least one of a side surface of the first translucent substrate or a side surface of the second translucent substrate; and

a display controller including:an external light analyzer configured to set, in accordance with a received signal of external light information, a second color gamut different from a first color gamut displayable when the external light is not present; anda signal adjuster configured to convert in color a first pixel input signal into a second pixel input signal that reduces a color shift of a second reproduced color reproduced in the second color gamut from a first reproduced color reproduced in the first color gamut in accordance with the first pixel input signal.(2) The display device according to (1), wherein

the first translucent substrate has a first principal surface and a second principal surface that is a plane parallel to the first principal surface,

the second translucent substrate has a first principal surface and a second principal surface that is a plane parallel to the first principal surface, and

when the polymer dispersed liquid crystal is in a non-scattering state, a background on the first principal surface side of the second translucent substrate is visible from the first principal surface of the first translucent substrate, or a background on the first principal surface side of the first translucent substrate is visible from the first principal surface of the second translucent substrate.(3) The display device according to (1) or (2), further comprising a first electrode and a second electrode interposing the liquid crystal layer therebetween, wherein

the light emitter is configured to sequentially emit light of a first color, light of a second color, and light of a third color using a field-sequential system, and

the display controller is configured to control the light emitter to emit the light of the first color, the light of the second color, and the light of the third color at the same light emission intensity, and applies a voltage to the first electrode according to a gradation value of each of the first color, the second color, and the third color in accordance with the second pixel input signal.(4) The display device according to any one of (1) to (3), wherein the signal adjuster is configured to convert a first input color of the first pixel input signal into a second input color of the second pixel input signal using a third color conversion matrix obtained by multiplying a first color conversion matrix to convert a red-green-blue (RGB) signal in the first color gamut into tristimulus values (X,Y,Z) by an inverse matrix of a second conversion matrix to convert the RGB signal into tristimulus values (X+X′,Y+Y′,Z+Z′) in the second color gamut based on external light tristimulus values (X′,Y′,Z′).(5) A display device comprising:

a first translucent substrate;

a second translucent substrate facing the first translucent substrate;

a liquid crystal layer including polymer dispersed liquid crystal sealed between the first translucent substrate and the second translucent substrate;

at least one light emitter facing at least one of a side surface of the first translucent substrate or a side surface of the second translucent substrate;

a display controller including:an external light analyzer configured to set, in accordance with a received signal of external light information, a second color gamut different from a first color gamut displayable when the external light is not present; anda signal adjuster configured to convert in color a first pixel input signal into a second pixel input signal that reduces a color shift of a second reproduced color reproduced in the second color gamut from a first reproduced color reproduced in the first color gamut in accordance with the first pixel input signal; and

a first electrode and a second electrode interposing the liquid crystal layer therebetween, wherein

the light emitter is configured to sequentially emit light of a first color, light of a second color, and light of a third color based on a light emitter control value using a field-sequential system, and

the display controller is configured to:compare a gradation value of the first color, a gradation value of the second color, and a gradation value of the third color in the first pixel input signal with a gradation value of the first color, a gradation value of the second color, and a gradation value of the third color in the second pixel input signal on a color-by-color basis, and calculate, based on a higher gradation value of each of the colors, a gradation value of the first color, a gradation value of the second color, and a gradation value of the third color for a third pixel input signal;sequentially apply a voltage to the first electrode according to the gradation value of the first color, the gradation value of the second color, and the gradation value of the third color of the third pixel input signal; andset the light emitter control value for a color having the same gradation value as that of the first pixel input signal among the gradation value of the first color, the gradation value of the second color, and the gradation value of the third color of the third pixel input signal to a value lower than the light emitter control value for a color having the same gradation value as that of the second pixel input signal among the gradation value of the first color, the gradation value of the second color, and the gradation value of the third color of the third pixel input signal.(6) The display device according to (5), wherein the light emitter control value is a light emission intensity.(7) The display device according to (5), wherein the light emitter control value is a duty ratio of pulse width modulation.(8) The display device according to any one of (1) to (7), wherein, when the second reproduced color is outside the second color gamut, the signal adjuster is configured to convert in color the first pixel input signal into the second pixel input signal such that the second reproduced color is reproducible at an outer border of the second color gamut.(9) The display device according to any one of (1) to (8), further comprising an external light setter configured to receive the signal of the external light information, wherein

the external light setter is a visible light sensor, and is configured to generate the signal of the external light information according to visible light of the external light detected by the external light setter.(10) The display device according to any one of (1) to (8), further comprising an external light setter configured to receive the signal of the external light information, wherein

the external light setter is a setting switch capable of changing a set value of the external light information set in advance according to visible light of the external light, and is configured to generate the signal of the external light information based on the set value of the external light information.