JP2001042326A - Electro-optical device and electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance utilization efficiency of light emitted by an illumination by providing an illuminating means capable of emitting a light beam having maximum intensity of wavelength in a range except a prescribed range to an electro-optical device. SOLUTION: A liquid crystal cell 51 as an electro-optical device is constituted of a liquid crystal optical layer 50 as an electro-optical layer interposed between a first substrate 10 and a second substrate 20. A polarizer 28 including a dichroic dyestuff and a 1/4 wavelength plate 22 are provided in front of the liquid crystal cell 51. A semi-transmission reflection layer 26 including a cholesteric liquid crystal optical layer is provide in a back face of a semi- transmission type liquid crystal device and a back light 80 as an illuminator is provided in the back face of the semi-transmission reflection layer. The back light 80 is provided with a light source 82 and light transmission plate 81. Light emitted by the light source 82 is light-guided and diffused by the light transmission plate 81 so as to made incident to all picture elements of the liquid crystal cell 51 The back light 80 is capable of emitting a light beam having maximum intensity of wavelength in a range except a prescribed range to the liquid crystal cell 51 which is the electro-optical device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electro-optical device for forming an image by applying a voltage to an electro-optical material sandwiched between substrates. In particular, the present invention relates to a so-called transflective electro-optical device that functions as a reflective display device in a bright place and functions as a transmissive display device in a dark place.

[0002]

2. Description of the Related Art Electro-optical devices, for example, TN liquid crystal between substrates,
A liquid crystal device sandwiching an STN liquid crystal or the like is often used as a display portion of an electronic device such as a mobile phone or a portable information device. In these electronic devices, a semi-transmissive reflective electro-optical device performs display mainly in a bright place using external light, and performs display mainly in a dark place using light emitted from a lighting device provided on a back surface. Is generally used.

[0003] Such an electro-optical device mainly reflects light in a predetermined wavelength range of visible light wavelengths such as a polarizing plate described in JP-A-8-271731, When a transflective layer mainly transmitting light is used, brighter reflected light and transmitted light can be obtained as compared with a polarizing plate containing a dichroic dye.

[0004] However, since the wavelength region mainly illuminated by the illumination device is within the wavelength region mainly reflected by the transflective layer, the efficiency of use of light emitted from the illumination device is low.

[0005]

SUMMARY OF THE INVENTION In an electro-optical device using the transflective layer, it is an object of the present invention to improve the utilization efficiency of light emitted from the illumination device.

[0006]

In order to solve the above problems, the present invention has the following arrangement. That is, the electro-optical device of the present invention is an electro-optical element having an electro-optical layer between substrates, a lighting device provided on the back side of the electro-optical element and emitting light toward the electro-optical element, A semi-transmissive reflection layer provided between the electro-optical element and the lighting device, mainly reflecting light in a predetermined wavelength range of visible wavelength light, and mainly transmitting visible wavelength light in wavelengths other than the predetermined wavelength range. Wherein the illuminating means is capable of irradiating the electro-optical element with light having a maximum intensity wavelength outside the predetermined range.

According to the electro-optical device of the present invention, since most of the light emitted from the lighting device can pass through the semi-transmissive reflection layer, the utilization efficiency of the light emitted from the lighting device is improved. Can be.

Further, it is preferable that the transflective layer is provided between the electro-optical layer and one of the substrates. This is because the so-called double image caused by the thickness of the lower substrate is not generated by forming the transflective layer on the inner side of the electro-optical element as in the present example.

It is preferable to use a colored light source such as an LED element and an EL element as a lighting device in the electro-optical device. Of course, these colored light sources and a light guide plate that emits light from the colored light sources toward the electro-optical element may be combined as an illumination unit.

In the electro-optical device, the front surface of the electro-optical element refers to a surface on which a user views a displayed image, and the back surface refers to a surface opposite to the front surface. .

In one embodiment of the present invention, the present invention is characterized in that the present invention is a polarizing beam splitter having a cholesteric liquid crystal optical layer in the transflective layer.

In this embodiment, a polarizer including a dichroic element and a λλ wavelength plate are arranged on the front surface of the electro-optic layer, so that light incident on the electro-optic layer is circularly polarized, and The display at the time of reflection can be performed by selecting the clockwise circular polarization or the counterclockwise circular polarization of the light incident on the polarization separation plate having the cholesteric liquid crystal optical layer by an electric signal applied to the layer. .

[0013] Further, in the display at the time of transmission, a circularly polarized light transmitted from a polarization separation plate having a cholesteric liquid crystal optical layer is incident on the electro-optic layer, and a polarizer containing a dichroic dye is applied to the electro-optic layer by a voltage applied to the electro-optic layer. By selecting the axial direction of the linearly polarized light that is incident on the display, it is possible to perform display during transmission.

Further, by disposing a λλ wavelength plate between the polarization separation plate having the cholesteric liquid crystal optical layer and the electro-optic layer, the transflective layer can be a linear polarization separation plate. Depending on the voltage applied to the electro-optic layer,
Display can be performed by selecting the linear polarization direction.

By disposing a polarizer containing a dichroic dye between the quarter-wave plate and the electro-optical layer,
A higher degree of polarization can be obtained.

As the transflective layer in the above-described electro-optical device, Japanese Patent Application No. 1-133003 and Japanese Patent Application No. 8-27 are disclosed.
No. 1731 can be used.

In another embodiment of the present invention, a dielectric filter is used for the transflective layer. By overlapping the dielectric filter layers, reflection over a wide wavelength range can be obtained, and high reflection efficiency can be obtained.

In another embodiment of the present invention, a hologram is used for the transflective layer. As the transflective layer in this example, JP-A-10-9679
The hologram layer described in No. 2 can be used.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below more specifically with reference to the drawings.

First Embodiment First, the structure of an electro-optical device according to a first embodiment of the present invention will be described with reference to FIGS. In the first embodiment, the present invention is applied to a transflective liquid crystal device of a passive matrix driving system. FIG. 2 is a schematic cross-sectional view of the transflective liquid crystal device 54 showing a cross section taken along line AA ′ of FIG. 1 and 2
In the figure, for convenience of explanation, six stripe electrodes are shown in each of the vertical and horizontal directions, but actually, there are many electrodes, and FIG.
1. In order to make each layer and each member in FIG. 2 a size recognizable on the drawing, the scale is different for each layer and each member.

Referring to FIGS. 1 and 2, the transflective liquid crystal device 54 of the first embodiment has a liquid crystal optical layer 50 sandwiched between a first substrate 10 and a second substrate 20 as an electro-optical layer. A liquid crystal cell 51 as an electro-optical element is configured. A polarizer 28 containing a dichroic dye and a ４ wavelength plate 2 are provided on the front surface (ie, the upper surface in FIG. 2) of the liquid crystal cell 51.
2 are arranged. Further, the transflective layer 26 including the cholesteric liquid crystal optical layer is disposed on the back surface of the transflective liquid crystal device 54 (ie, the lower surface in FIG. 2).
A backlight 80 as an illuminating device is arranged on the back of the camera. In this example, the transflective layer 26 is disposed between the first substrate 10 and the backlight 80, but may be disposed between the first substrate 10 and the liquid crystal optical layer 50.

The liquid crystal cell 51 is arranged so that the striped transparent electrode 11 formed on the transparent first substrate 10 and the striped transparent electrode 21 formed on the transparent second substrate cross each other. It is configured. The first substrate 10 and the second substrate 20 are separated from each other around the liquid crystal optical layer 50 by a sealant 31 and a sealant 32.
It is sealed between the substrates 20. In addition, although it is drawn so that there may be a gap between the elements constituting the transflective liquid crystal device, this is for convenience of illustration, and in fact, the elements are almost in close contact with each other. .

The transflective layer 26 including the cholesteric liquid crystal optical layer is formed, for example, of a polymer liquid crystal composed of the cholesteric liquid crystal optical layer such that the helical axis of the cholesteric structure is perpendicular to the first substrate 10. . Since the cholesteric liquid crystal optical layer performs selective reflection, it is preferable that two or more cholesteric liquid crystal optical layers having different helical periods are superposed. Note that a scattering layer may be used for the transflective layer 26 and the liquid crystal optical layer 50 in order to reflect the incident light even in a direction shifted from the direction of the specularly reflected light.

A backlight 80 as a lighting device includes a light source 82 and a light guide plate 81 as shown in FIG.
The light emitted from the light source 82 is guided and diffused by the light guide plate 81 so that the light enters all the pixels of the liquid crystal cell 51. An acrylic plate is generally used as the light guide plate 81, and a light guide plate made of an acrylic light guide plate and a diffusion plate or a light collecting prism laminated thereon may be used. As the light source 82, L
A point light source such as an ED (light emitting diode) or a linear light source such as a cathode ray tube is used. Note that, instead of the combination of the light source 82 and the light guide plate 81, an EL (electroluminescent), which is a surface light source, may be used as the backlight.

FIG. 3 shows the transmission characteristics of the transflective layer including the cholesteric liquid crystal optical layer used in this embodiment. In this transflective layer, the wavelength region where the transmittance is 10% or more is approximately 400 nm to 550 nm and 650 nm to 750 nm. FIG. 4 shows the spectral characteristics of the backlight used in this embodiment. This backlight can emit blue light, and its peak is at 450 nm to 500 nm. Therefore, light emitted from the backlight can efficiently pass through the transflective layer.

In this embodiment, a backlight capable of emitting blue light is used. However, a backlight capable of emitting red light or green light may be used.

The liquid crystal cell 51 also includes, in addition to the components shown in FIGS. 1 and 2, an alignment film provided facing the liquid crystal optical layer 50, a driving circuit, a spacer, and the like.

<Operation as a Reflective Liquid Crystal Display> The principle of operation when the transflective liquid crystal device 54 formed as described above is used as a reflective type under bright light will be described with reference to FIG. Will be explained.

FIG. 5A shows a case where the liquid crystal cell 51 is in a switching state in which there is no phase difference with respect to the polarization plane of the light passing therethrough.
(B) shows that the liquid crystal cell 51 has 3
This shows a case where the switching state has a phase difference of / 4 wavelength.

In FIG. 5 and other similar figures, the symbols of the arrows indicating the left and right directions indicate the polarization plane or the axial direction parallel to the plane of the paper, and the small black circles in the circles indicate the polarization plane or the plane perpendicular to the plane of the paper. The axial direction is shown.

First, the case where the external light 67 is incident on the switching state region where the liquid crystal optical layer 50 has no phase difference, that is, the case shown in FIG. 5A will be described. In this case, when the incident external light 67 passes through the polarizer 28, it becomes linearly polarized light 67a having a polarization plane in the direction of the transmission axis 28T. Further, the linearly polarized light 67a becomes circularly polarized light 67b by passing through the quarter-wave plate 22, passes through the liquid crystal cell 51 with almost no change in the polarization state, and is reflected by the transflective layer 26 including the cholesteric liquid crystal optical layer. Is done. At this time, the sense of the circularly polarized light is determined by the axis angle of the polarizer 28 and the axis angle of the quarter-wave plate 22,
In this example, the counterclockwise circularly polarized light is used. The circularly polarized light 67c reflected by the transflective layer 26 passes through the liquid crystal optical layer 50 without substantially changing the polarization state, and is converted into linearly polarized light 67d by the quarter-wave plate 22. At this time, since the plane of polarization of the linearly polarized light 67d is substantially parallel to the transmission axis 28T of the polarizer 28, it passes through the polarizer 28 and reaches the display surface.
Therefore, bright display is obtained in the display area in such a state.

Next, the case where the liquid crystal cell 51 is in a switching state having a phase difference of 3/4 wavelength with respect to the polarization plane of the light passing through the liquid crystal optical element 51, ie, the case shown in FIG. explain. In this case, when the incident external light 69 passes through the polarizer 28, it becomes linearly polarized light 69a having a polarization plane in the direction of the transmission axis 28T. Further, the linearly polarized light 69a becomes a circularly polarized light 69b by transmitting through the quarter-wave plate 22, and becomes a circularly polarized light 69c in a direction opposite to the circularly polarized light 69b by passing through the liquid crystal optical layer 50.
The circularly polarized light 69c transmits through the transflective plate 26 including the cholesteric liquid crystal optical layer. Therefore, dark display is performed in the display area in such a state.

<Operation as Transmissive Liquid Crystal Display Device> The principle of operation when the transflective liquid crystal device 54 is used as a transmissive liquid crystal device in a dark environment will be described with reference to FIG.

FIG. 6A shows a case where the liquid crystal cell 51 is in a switching state having no phase difference with respect to the polarization plane of the passing light, and FIG. 6B on the right half shows the polarization plane of the passing light. 5 shows a case where the liquid crystal cell 51 is in a switching state having a phase difference of 3/4 wavelength.

First, when the light 160 is incident from the backlight 80 to the switching state where the liquid crystal cell 51 does not have a phase difference with respect to the polarization plane of the light passing through the liquid crystal optical element 51, that is, FIG. The case shown in FIG. The light 160 emitted from the backlight 80 passes through the transflective layer 26 including the cholesteric liquid crystal optical layer to become clockwise circularly polarized light 160a, and passes through the liquid crystal cell 51 with almost no change in the polarization state.
The circularly polarized light 160a becomes the linearly polarized light 160b by passing through the quarter wave plate 22. At this time, the linearly polarized light 16
Since the polarization plane of 0b is substantially orthogonal to the transmission axis 28T of the polarizer 28, it is substantially absorbed by the polarizer 28 and does not reach the display surface. Therefore, dark display is performed in the display area in such a state.

Next, the case where the liquid crystal cell 51 is in a switching state in which the liquid crystal cell 51 has a phase difference of 3/4 wavelength with respect to the polarization plane of the light passing through the liquid crystal optical layer 50, that is, the case shown in FIG. Will be described. The light 161 emitted from the backlight 80 passes through the transflective layer 26 including the cholesteric liquid crystal optical layer, so that the clockwise circularly polarized light 161 is emitted.
a. The circularly polarized light 161a becomes a circularly polarized light 161b in the opposite direction when passing through the liquid crystal optical layer 50, and becomes a linearly polarized light 161c by transmitting through a quarter-wave plate. At this time, since the plane of polarization of the linearly polarized light 161c is substantially parallel to the transmission axis 28T of the polarizer 28, it passes through the polarizer 28 and reaches the display surface.
Therefore, bright display is obtained in the display area in such a state.

It should be noted that the transflective liquid crystal device 54 can also perform an intermediate display between a bright state and a dark state.

Further, in this embodiment, the example using the passive matrix driving method has been described, but the TFD driving method (Th
in Film Diode), MIM drive method (Metal Insulator)
An active matrix driving method such as a metal structure) or a TFD driving method may be used.

Second Embodiment First, the structure of an electro-optical device according to a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, the present invention is applied to a passive matrix driving type transflective liquid crystal device.
FIG. 7 is a schematic cross-sectional view of the transflective liquid crystal device 55.

Referring to FIG. 7, a transflective liquid crystal device 55 according to the second embodiment has a liquid crystal optical layer 50 sandwiched between a first substrate 10 and a second substrate 20 as an electro-optical element. As a liquid crystal cell 51. Polarizer 2 including dichroic dye on front surface of liquid crystal cell 51
8, a transflective layer 26 including a cholesteric liquid crystal optical layer is disposed on the back surface of the transflective liquid crystal device 55, and a transflective layer 26 between the liquid crystal optical layer 50 and the transflective layer 26 including the cholesteric liquid crystal optical layer. A / 4 wavelength plate 22 is provided. Further, a backlight 80 as an illumination device is arranged on the back surface of the transflective layer 26.

The transflective layer 26 including the cholesteric liquid crystal optical layer is formed, for example, by forming a polymer liquid crystal comprising the cholesteric liquid crystal optical layer such that the helical axis of the cholesteric structure is perpendicular to the first substrate 10. . Since the cholesteric liquid crystal optical layer performs selective reflection, it is preferable that two or more cholesteric liquid crystal optical layers having different helical periods are superposed. Note that a scattering layer may be used between the transflective layer 26 and the liquid crystal optical layer 50 in order to reflect the incident light even in a direction shifted from the direction of the specularly reflected light.

As the backlight 80 as an illumination device, a backlight having a maximum intensity wavelength within a wavelength region where the transflective layer mainly transmits can be used as in the first embodiment.

<Operation of Reflective Liquid Crystal Display> The principle of operation when the transflective liquid crystal device 55 formed as described above is used as a reflective type under bright light will be described with reference to FIG. Will be explained.

In FIG. 8, the left half of FIG.
FIG. 8A shows a case where the liquid crystal cell 51 is in a switching state in which the passing light is not rotated, and FIG.
Indicates a case where the liquid crystal cell 51 is in a switching state in which the polarization plane of the passing light is rotated by 90 °.

First, the external light 66 is set in a switching state region where the polarization plane of the light passing through the liquid crystal optical element 51 is not rotated.
Will be described, that is, the case shown in FIG. In this case, the incident external light 66 is the polarizer 2
8, the light becomes a linearly polarized light 66a having a polarization plane in the direction of the transmission axis 28T. The linearly polarized light 66a passes through the liquid crystal cell 51 without substantially changing the polarization state, and
It reaches the 波長 wavelength plate 22. The linearly polarized light 66a passes through the quarter-wave plate 22 to become circularly polarized light 66b, and is reflected by the transflective layer 26 including the cholesteric liquid crystal optical layer. At this time, the sense of the circularly polarized light is determined by the angle of the orientation direction of the quarter-wave plate 22 and the liquid crystal optical layer 50, and in the present example, the circularly polarized light is counterclockwise. Transflective layer 2
The circularly-polarized light 66c reflected by 6
Through the liquid crystal optical layer 50 with almost no change in the polarization state. At this time, the polarization plane of the linearly polarized light 66d is the polarizer 28.
Is substantially parallel to the transmission axis 28T, and passes through the polarizer 28 to reach the display surface. Therefore, bright display is obtained in the display area in such a state.

Next, the case where the liquid crystal optical element 51 is in a switching state in which the polarization plane of the light passing therethrough is rotated by 90 °, that is, the case shown in FIG. 8B will be described. In this case, when the incident external light 68 passes through the polarizer 28, it becomes a linearly polarized light 68 a having a polarization plane in the direction of the transmission axis 28 T, and passes through the liquid crystal optical layer 50 to become 9.
The light is rotated by 0 ° and becomes linearly polarized light 68b. This linearly polarized light 68b
When passing through a １ ／ wavelength plate, the light becomes circularly polarized light 68 c, but becomes clockwise circularly polarized light, so that it is transmitted through the transflective plate 26 including the cholesteric liquid crystal optical layer. Therefore, dark display is performed in the display area in such a state.

<Operation as Transmissive Liquid Crystal Display Device> The principle of operation when the transflective liquid crystal device 55 is used as a transmissive liquid crystal device in a dark environment will be described with reference to FIG.

In FIG. 9, the left half of FIG.
9A shows a switching state in which the liquid crystal cell 51 does not rotate the polarization plane of the passing light, and FIG. 9B in the right half shows a switching state in which the polarization plane of the passing light rotates 90 °. Is shown.

First, when the light 60 from the backlight 80 is incident on the switching region where the polarization plane of the light passing through the liquid crystal optical element 51 is not rotated, that is, FIG.
The case shown in FIG. Backlight 8
The light 60 emitted from 0 passes through the transflective layer 26 including the cholesteric liquid crystal optical layer to become clockwise circularly polarized light 60a. Further, the light becomes linearly polarized light 60b in the quarter-wave plate 22, enters the liquid crystal optical layer 50, and passes therethrough without substantially changing the polarization state. At this time, since the plane of polarization of the linearly polarized light 60b is substantially orthogonal to the transmission axis 28T of the polarizer 28, it is substantially absorbed by the polarizer 28 and does not reach the display surface. Therefore, dark display is performed in the display area in such a state.

Next, the case where the liquid crystal optical layer 50 is in a switching state in which the polarization plane of the light passing therethrough is rotated by 90 °, that is, the case shown in FIG. 9B will be described. The light 61 emitted from the backlight 80 passes through the transflective layer 26 including the cholesteric liquid crystal optical layer to become clockwise circularly polarized light 61a. Further, the light becomes the linearly polarized light 61b in the quarter-wave plate 22, enters the liquid crystal optical layer 50, and the polarization plane rotates 90 ° to become the linearly polarized light 61c.
At this time, the linearly polarized light 61c is transmitted through the transmission axis 28T of the polarizer 28.
And is substantially parallel to the display surface, and reaches the display surface. Therefore, bright display is obtained in the display area in such a state.

It should be noted that the transflective liquid crystal device 55 can also perform an intermediate display between a bright state and a dark state.

In this embodiment, a so-called TN liquid crystal element in which the liquid crystal optical layer 50 is twisted by 90 ° is used, but an STN liquid crystal element or the like may be used.

Further, in this embodiment, an example using a passive matrix driving method has been described, but an active matrix driving method such as D-TFD, DMTN or TFT may be used. Third Embodiment The configuration of an electro-optical device according to a third embodiment of the present invention will be described with reference to FIG. Third
The transflective liquid crystal display device 56 according to the embodiment is different from the second embodiment in that the polarizer 24 containing a dichroic dye is disposed between the liquid crystal optical layer 50 and the quarter-wave plate 22. .
The other configuration is the same as that of the second embodiment, and a detailed description of the configuration will be omitted.

In the second embodiment, the light that has passed through the quarter-wave plate 22 and the transflective layer 26 including the cholesteric liquid crystal optical layer and is reflected or transmitted is not actually linearly polarized light but elliptically polarized light. Therefore, by arranging the polarizer 24 between the quarter-wave plate 22 and the liquid crystal element 50 such that the optical axis of the quarter-wave plate is shifted by 45 °, it is possible to obtain linearly polarized light with a higher degree of polarization. .

(Fourth Embodiment) The structure of an electro-optical device according to a fourth embodiment of the present invention will be described with reference to FIG.
In the fourth embodiment, the present invention is applied to a transflective liquid crystal device of a passive matrix driving system. FIG. 11 is a schematic sectional view of the transflective liquid crystal device 57. In FIG. 11, for convenience of explanation, six stripe-shaped electrodes are shown in each of the vertical and horizontal directions. However, in reality, many electrodes exist, and each layer and each member in FIG. 11 are large enough to be recognized on the drawing. For the sake of simplicity, the scale is different for each layer and each member.

In FIG. 11, the transflective liquid crystal device 57 of the fourth embodiment includes a first substrate 10 and a second substrate 20.
The liquid crystal optical layer 50 as an electro-optical element is sandwiched between the liquid crystal optical layer 50 and the liquid crystal cell 51 as an electro-optical element. The polarizer 28 containing a dichroic dye is disposed on the front surface of the liquid crystal cell 51, and the retardation film 25 is disposed between the polarizer 28 and the liquid crystal cell 51. Further, a transflective layer 23 made of a dielectric mirror is arranged on the back of the transflective liquid crystal device 57, and a backlight 80 as an illumination device is arranged on the back of the transflective layer 23.

The transflective layer 23 made of a dielectric mirror
Is formed, for example, by alternately laminating thin films of silicon dioxide SiO ₂ and titanium dioxide: TiO ₂ by a sputtering method or the like. Note that a scattering layer may be used between the transflective layer 23 and the liquid crystal optical layer 50 in order to reflect the incident light even in a direction shifted from the direction of the specularly reflected light.

A backlight 80 as an illumination device includes a light source 82 and a light guide plate 81 as shown in FIG. The light emitted from the light source 82 is guided and diffused by the light guide plate 81 so that the light enters all the pixels of the liquid crystal cell 51. An acrylic plate is generally used as the light guide plate 81, and a light guide plate made of an acrylic light guide plate and a diffusion plate or a light collecting prism laminated thereon may be used. As the light source 82, an LED (light emitting diode) or the like is used. Note that, instead of the combination of the light source 82 and the light guide plate 81, an EL (electroluminescent), which is a surface light source, may be used as the backlight.

FIG. 12 shows the transmission characteristics of the transflective layer 23 made of a dielectric mirror used in this embodiment. This transflective layer has a wavelength region where the transmittance is 30% or more, which is approximately 40%.
It is 0 nm to 620 nm. FIG. 13 shows the spectral characteristics of the backlight used in this embodiment. This backlight can emit blue light, and its peak is 500
nm to 550 nm. Therefore, light emitted from the backlight can efficiently pass through the transflective layer.

In the embodiment, a backlight capable of emitting green light is used. However, a backlight capable of emitting red light or blue light may be used.

The liquid crystal cell 51 includes, in addition to the components shown in FIG. 11, an alignment film provided facing the liquid crystal optical layer 50, a driving circuit, a spacer, and the like.

<Operation of Reflective Liquid Crystal Display> The principle of operation when the transflective liquid crystal device 57 formed as described above is used as a reflective type under bright light will be described with reference to FIG. Will be explained.

In FIG. 14, the left half of FIG.
14A shows a case where the liquid crystal cell 51 is in a switching state in which there is no phase difference with respect to the polarization plane of the passing light, and FIG. A case 51 is a switching state having a quarter wavelength phase difference.

First, the case where external light is incident on a switching state region having no phase difference with respect to the polarization plane of light passing through the liquid crystal optical element 51, that is, the case shown in FIG. 14A will be described. In this case, when the incident external light 62 passes through the polarizer 28, it becomes linearly polarized light 62a having a polarization plane in the direction of the transmission axis 28T. The linearly polarized light 62a passes through the retardation film 25,
Thus, the circularly polarized light 62b passes through the liquid crystal cell 51 without substantially changing the polarization state, and is reflected by the semi-transmissive reflection layer 23 made of a dielectric mirror. At this time, the sense of the circularly polarized light is determined by the axial directions of the retardation film 25 and the deflector 28, and in this example, the circularly polarized light is counterclockwise. The circularly polarized light 62c reflected by the transflective layer 23 passes through the liquid crystal cell 51 with almost no change in the polarization state, and passes through the retardation film 25 to become linearly polarized light 62d. At this time, since the plane of polarization of the linearly polarized light 62d is substantially perpendicular to the transmission axis 28T of the polarizer 28,
, And does not reach the display surface. Therefore, dark display is performed in the display area in such a state.

Next, the case where the liquid crystal optical element 51 is in a switching state having a λ / 4 wavelength phase difference with respect to the polarization plane of the light passing therethrough, that is, the case shown in FIG. 14B will be described. In this case, the incident external light 63 is the polarizer 2
8, the light becomes a linearly polarized light 63a having a polarization plane in the direction of the transmission axis 28T, and the linearly polarized light 63a becomes a circularly polarized light 63b by passing through the retardation film 25.
The circularly polarized light 63b passes through the liquid crystal cell 51, and becomes linearly polarized light 63c.
The light is reflected by the semi-transmissive reflection layer 23 made of a dielectric mirror. The linearly polarized light 63d reflected by the transflective layer 23 passes through the liquid crystal cell 51 to become circularly polarized light 63e, and passes through the retardation film 25 to become linearly polarized light 63f. At this time, since the plane of polarization of the linearly polarized light 63f is substantially parallel to the transmission axis 28T of the polarizer 28, it passes through the polarizer 28 and reaches the display surface. A bright display is obtained in the display area in such a state.

It should be noted that the transflective liquid crystal device 54 can also perform an intermediate display between a bright state and a dark state.

<Operation as Transmissive Liquid Crystal Display Device> The principle of operation when the transflective liquid crystal device 57 is used as a transmissive liquid crystal device in a dark environment will be described with reference to FIG.

In FIG. 15, the left half of FIG.
15A shows a case where the liquid crystal cell 51 is in a switching state in which there is no phase difference with respect to the polarization plane of the passing light, and FIG. A case 51 is a switching state having a quarter wavelength phase difference.

First, when the light 64 is incident from the backlight 80 into the switching state region where the liquid crystal cell 51 has no phase difference with respect to the polarization plane of the light passing through the liquid crystal optical element 51, that is, FIG. The case shown is described. The light 64 emitted from the backlight 80 passes through the polarizer 101 to become linearly polarized light 64a,
The light passes through the phase difference plate 102 to become circularly polarized light 64b, and the circularly polarized light 64c within the wavelength range that can be mainly transmitted by the semi-transmissive reflection layer 23 made of a dielectric mirror is transmitted.
The circularly polarized light 64b passes through the liquid crystal 51 without substantially changing the polarization state, and becomes linearly polarized light 64d by passing through the retardation film 22. Since the linearly polarized light 64d is substantially perpendicular to the transmission axis 28T of the polarizer 28, the polarizer 28
, And does not reach the display surface. Therefore, dark display is performed in the display area in such a state.

Next, the case where the liquid crystal optical element 51 is in a switching state having a phase difference of 1/4 wavelength with respect to the polarization plane of the light passing therethrough, that is, the case shown in FIG. 15B will be described. . The light 65 emitted from the backlight 80 becomes linearly polarized light 65a by passing through the polarizer 101, becomes circularly polarized light 64b by passing through the retardation plate 102, and is mainly transmitted by the semi-transmissive reflection layer 23 made of a dielectric mirror. Circularly polarized light 65 within the possible wavelength range
c is transmitted, and the circularly polarized light 65c is converted into circularly polarized light 65d in the opposite direction by the liquid crystal cell 51. The circularly polarized light 65d becomes linearly polarized light 65e by passing through the retardation film 22. Since the linearly polarized light 65e is substantially parallel to the transmission axis 28T of the polarizer 28, it passes through the polarizer 28 and reaches the display surface. Therefore, bright display is performed in such a display area.

(Fifth Embodiment) An electro-optical device 57 according to a fifth embodiment of the present invention is different from the fourth embodiment in that the transflective layer uses a hologram reflector instead of a dielectric mirror. The other configuration is the same as that of the fourth embodiment, and a detailed description of the configuration will be omitted.

(Sixth Embodiment) This embodiment is an embodiment relating to the electronic apparatus of the present invention. By using the display device described in Embodiments 1 to 5 as a display member, reflection display by external light and transmissive display by a backlight can be performed, and light emitted from the backlight can be used efficiently. Bright and low power consumption.

Therefore, it is often used under external light and has a strong demand for low power consumption. Therefore, it is most suitable as a display device of a portable electronic device such as a mobile phone, a clock, and a pager.

Further, since the light of the backlight can be used efficiently, a clear display can be obtained even in a dark place, and reading errors of the display can be reduced.

[0075]

According to the display device of the first aspect of the present invention, when performing transmissive display using light emitted from the light source, the light emitted from the light source can be used efficiently, and the display device is bright and low. A display device which is easy to see with power consumption can be provided.

According to the display device of the second aspect, it is possible to provide a display device which is easy to see because the display cannot be shadowed when performing reflection display using external light.

According to the display device of the third aspect, a transflective layer which is a circularly polarized light separating plate that can be easily manufactured can be obtained.

According to the display device of the fourth aspect, a transflective layer which is a linearly polarized light separating plate can be obtained.

According to the display device of the fifth aspect, a transflective layer which is a linearly polarized light separating plate having a higher degree of polarization can be obtained.

According to the display device of the sixth aspect, a transflective layer which can be easily manufactured can be obtained.

According to the display device of the seventh aspect, it is possible to provide a display device capable of obtaining bright reflection at an angle deviating from regular reflection.

According to the display device of the eighth aspect, a bright and vivid display that is easy to see under external light can be obtained, and a bright and easy-to-view display can be provided with low power consumption even in a dark place.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a transflective liquid crystal device according to a first embodiment.

FIG. 2 is a cross-sectional view showing the structure of the transflective liquid crystal device according to the first embodiment.

FIG. 3 is a diagram illustrating transmission characteristics of a transflective layer including a cholesteric liquid crystal optical layer according to the first embodiment.

FIG. 4 is a diagram showing the spectral intensity of the backlight of the first embodiment.

FIG. 5 is a diagram illustrating an optical path of the transflective liquid crystal device according to the first embodiment during reflective display.

FIG. 6 is a diagram showing an optical path during transmissive display of the transflective liquid crystal device according to the first embodiment.

FIG. 7 is a sectional view showing the structure of a transflective liquid crystal device 55 according to a second embodiment.

FIG. 8 is a diagram showing an optical path of the transflective liquid crystal device 55 of the second embodiment at the time of reflective display.

FIG. 9 is a diagram illustrating an optical path during transmissive display of the transflective liquid crystal device 55 of the second embodiment.

FIG. 10 is a sectional view showing the structure of a transflective liquid crystal device 56 according to a third embodiment.

FIG. 11 is a diagram showing an optical path of the transflective liquid crystal device 57 of the third embodiment during reflective display.

FIG. 12 is a diagram illustrating transmission characteristics of a dielectric mirror according to a third embodiment.

FIG. 13 is a diagram showing the spectral intensity of backtite of the third example.

FIG. 14 is a diagram showing an optical path during transmissive display of the transflective liquid crystal device 57 of the third embodiment.

FIG. 15 is a diagram showing an optical path of the transflective liquid crystal device 57 of the third embodiment during reflective display.

[Explanation of symbols]

First substrate Transparent electrode 20 Second substrate 21 Transparent electrode 22 Quarter-wave plate 23 Dielectric mirror 24 Polarizer 25 Retardation film 26 Transflective layer including cholesteric liquid crystal layer 28 Polarizer Sealing material Sealing material 50 Liquid crystal optics Layer Liquid crystal cell 54 Transflective liquid crystal device Transflective liquid crystal device Transflective liquid crystal device Semitransflective liquid crystal device 67 Light path in the bright state at the time of reflective display in transflective device 54 69 Transflective device 54 Light path in the dark state during reflective display 160 Light path in the dark state during transmissive display in the transflective device 54 161 Light path in the bright state during transmissive display in the transflective device 54 Light during reflective display in the transflective device 55 Optical path in state 68 Optical path in dark state during reflective display in transflective device 60 Transmissive display in transflective device 55 Light path 61 in the light state during transmissive display in the transflective device 55 62 light path in the dark state during reflective display in the transflective device 57 63 light path in the bright state during reflective display in the transflective device 57 Light path in a dark state during transmissive display in transflective device 57 Light path in a bright state during transmissive display in transflective device 57 Backlight Light guide plate Light source 101 Polarizer 102 Phase difference film

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09F 9/00 336 G09F 9/00 336E F-term (Reference) 2H042 DA06 DA08 DA08 DA11 DB01 DB02 DE00 2H049 BA02 BA03 BA07 BA17 BB03 BB63 BB66 BC22 CA05 CA09 CA11 2H091 FA10Z FA12Z FA15Z FA19Z FA41Z FB02 FB06 FC02 FD06 FD10 FD13 FD23 HA07 HA10 LA13 LA18 5G435 AA03 AA17 BB12 BB15 BB16 DD11 DD13 EE25 FF03 FF05 GG12 FF03 GG02

Claims (8)

[Claims] An electro-optic element having an electro-optic layer between substrates; a lighting device provided on a back side of the electro-optic element to emit light toward the electro-optic element; Between the illuminating device, comprises a semi-transmissive reflective layer that mainly reflects light in a predetermined wavelength range among visible light wavelengths, and mainly transmits visible wavelength light having a wavelength other than the predetermined range, An electro-optical device, wherein light having a maximum intensity wavelength outside a predetermined range can be emitted toward the electro-optical element. 2. The electro-optical device according to claim 1, wherein the transflective layer is provided between the substrate and the electro-optical layer. 3. The electro-optical device according to claim 1, wherein the transflective layer is a polarization separation plate having a cholesteric liquid crystal optical layer. 4. The electro-optical device according to claim 3, further comprising a quarter-wave plate between the transflective layer and the electro-optical layer. 5. The electro-optical device according to claim 4, further comprising a polarizer containing a dichroic dye between the electro-optical layer and the quarter-wave plate. . 6. The electro-optical device according to claim 1, wherein the transflective layer is a dielectric filter. 7. The electro-optical device according to claim 1, wherein the transflective layer is a hologram. 8. An electronic apparatus equipped with the electro-optical device according to claim 1.