JP2005241802A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wide viewing angle transflective liquid crystal display device. <P>SOLUTION: The transflective liquid crystal display device 1 is equipped with a light source side polarizing plate 180 and an observer side polarizing plate 100, a liquid crystal layer 140 disposed between the light source side polarizing plate 180 and the observer side polarizing plate 100, a light source 190 disposed on the rear side of the light source side polarizing plate 180, a transflective layer 150 disposed between the light source side polarizing plate 180 and the liquid crystal layer 143, an observer side optical retardation plate 120 disposed between the observer side polarizing plate 100 and the transflective layer 150, a light source side optical retardation plate 170 disposed between the light source side polarizing plate 180 and the transflective layer 150, and a light diffusion transmission layer 110 disposed between the observer side polarizing plate 100 and the transflective layer 150, diffusing light reflected on the transflective layer 150 in the reflective display mode, and on the other hand, interrupting diffusion of light transmitted by the transflective layer 150 and passed through the liquid crystal layer 143 and the observer side optical retardation plate 120 and transmitting it in the transmissive display mode. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a transflective liquid crystal display device.

  In recent years, with the spread of mobile phones and the like, the demand for transflective liquid crystal display devices with good color reproducibility and low power consumption is increasing.

  FIG. 7 is a cross-sectional view of a conventional transflective liquid crystal display device 2.

  The transflective liquid crystal display device 2 includes an observer side polarizing plate 200 and a light source side polarizing plate 280.

  A light source 290 is provided behind the light source side polarizing plate 280. The light source 290 is configured by, for example, a direct backlight, an edge light backlight, or the like, and uniformly displays the entire STN liquid crystal cell 240 when the transflective liquid crystal display device 2 displays an image in the transmissive display mode. It has a function of supplying light.

  An STN liquid crystal cell 240 for displaying an image is provided between the observer side polarizing plate 200 and the light source side polarizing plate 280.

  Between the observer side polarizing plate 200 and the STN liquid crystal cell 240, an observer side retardation plate 220 and a substrate 230 are provided.

  The observer-side retardation plate 220 has a function of performing phase modulation so that light reflected by the semi-transmissive reflective layer 250 and passed through the STN liquid crystal cell 240 is emitted from the observer-side polarizing plate 200.

  A transflective layer 250 is provided between the STN liquid crystal cell 240 and the light source side polarizing plate 280. The transflective layer 250 is, for example, a metal total reflection layer made of aluminum, silver, or the like provided with a light transmission opening that penetrates the metal total reflection layer in the thickness direction, or a metal thin film such as aluminum or silver. It is formed by a half mirror or the like. Accordingly, the transflective layer 250 reflects the light incident from the observer side polarizing plate 200 and passing through the STN liquid crystal cell 240, while transmitting the light emitted from the light source 290 and transmitted through the light source side polarizing plate 280. It has a function.

  Between the semi-transmissive reflective film 250 and the light source side polarizing plate 280, a substrate 260 and a light source side retardation plate 270 are provided. The light source side retardation plate 270 is emitted from the observer side polarizing plate 200, which is emitted from the light source 290, transmitted through the semi-transmissive reflection layer 250, and transmitted through the STN liquid crystal cell 240 and the observer side retardation plate 220. So that the phase is modulated.

  Therefore, the transflective liquid crystal display device 2 has a bright periphery and abundant external light incident from the observer-side polarizing plate 200, does not turn on the light source 290, and from the observer-side polarizing plate 200. Image display can be performed in a reflective display mode in which an image is displayed by reflecting incident external light by the semi-transmissive reflective layer 250.

  The transflective liquid crystal display device 2 turns on the light source 290 and emits from the light source 290 when the surrounding area is dark and the external light incident from the observer-side polarizing plate 200 is small. Image display can be performed in a transmissive display mode in which an image is displayed by light transmitted through 250.

  When the transflective liquid crystal display device 2 displays an image in the reflective display mode, external light incident from the observer-side polarizing plate 200 passes through the phase difference plate 220, the substrate 230, and the STN liquid crystal cell 240. The light is transmitted and reflected by the transflective reflection layer 250 to the viewer side. The light reflected by the transflective layer 250 is transmitted again through the STN liquid crystal cell 240, the substrate 230, and the phase difference plate 220, and is emitted from the viewer side polarizing plate 200 to the viewer side.

  When the surface on the viewer side of the semi-transmissive reflective layer 250 is configured as a mirror surface, most of the light incident from the viewer-side polarizing plate 200 is reflected by the semi-transmissive reflective layer 250 only in the front reflection direction. The light is emitted from the observer side polarizing plate 200. Therefore, the light reflected by the transflective layer 250 exhibits strong directivity. Therefore, there is a problem that the viewing angle of the transflective liquid crystal display device 2 is very narrow.

  In view of such problems, a transflective liquid crystal display device (for example, a light diffusing layer that diffuses light reflected by the transflective layer between the transflective layer and the observer-side polarizing plate (for example, , Patent Document 1) and a semi-transparent reflection layer provided with a semi-transparent reflection layer provided with a function of diffusing and reflecting light incident from an observer-side polarizing plate by forming an uneven shape on the surface of the translucent reflection layer on the observer side Semi-reflective liquid crystal display devices have been proposed.

  Among these transflective liquid crystal display devices, a liquid crystal display device having a light diffusion layer has a simpler structure than a liquid crystal display device having a transflective layer provided with a light diffusion function, and is manufactured at a low cost. In particular, research and development are actively conducted.

  FIG. 8 is a cross-sectional view of the transflective liquid crystal display device 3 having the light diffusion layer 304 described in Patent Document 1.

  The transflective liquid crystal display device 3 includes a liquid crystal cell 303 and a light source 308.

  On the light source 308, a prism sheet 306 and a light diffusion sheet 307 having a function of diffusing light emitted from the light source 308 are provided.

  On the liquid crystal cell 303, there are provided a light absorbing polarizing film 301 and a retardation plate 302 having a function of phase modulation so that light is transmitted through the liquid crystal cell 303 and emitted from the light absorbing polarizing film 301. ing.

  Further, a hard coat protective film 300 with an antireflection treatment is provided on the light absorbing polarizing film 301.

  A reflective polarizing layer 305 is provided between the light source 308 and the liquid crystal cell 303. The reflective polarizing layer 305 has a function of reflecting light incident from the viewer side and transmitting light emitted from the light source 308.

  A light diffusion layer 304 is provided between the prism sheet 306 and the reflective polarizing layer 305. The light diffusion layer 304 has a function of diffusing both light incident from the viewer side and light emitted from the light source 308.

When the transflective liquid crystal display device 3 displays an image in the reflective display mode, the light emitted from the light source 308 is diffused by the light diffusion sheet 307 and the prism sheet 306 and then is reflected on the reflective polarizing layer 305. Incident. The light incident on the reflective polarizing layer 305 is converted into linearly polarized light by the reflective polarizing layer 305, becomes scattered outgoing light by the forward scattering light diffusion layer 304, and enters the liquid crystal cell 303. The light incident on the liquid crystal cell 303 is transmitted through the phase difference plate 302, the light-absorbing polarizing film 301, and the hard coat protective film 300 with antireflection treatment and is emitted to the viewer side. Accordingly, it is described that the light emitted from the transflective liquid crystal display device 3 does not exhibit strong directivity, and the transflective liquid crystal display device 3 can realize a wide viewing angle.
JP 2001-235605 A

  However, when the transflective liquid crystal display device 3 displays an image in the transmissive display mode, the light emitted from the light source 308 and diffused by the diffusion sheet 307 and the prism sheet 306 is a forward scattering light diffusion. It is further diffused by the layer 304 and enters the liquid crystal cell 303. Therefore, the transflective liquid crystal display device 3 has a problem that the front luminance is low and the contrast is small when displaying an image in the transmissive display mode.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an image using a reflective display mode with a wide viewing angle and good visibility, and a transmissive display mode with high front luminance and high contrast. An object of the present invention is to provide a transflective liquid crystal display device capable of displaying.

A transflective liquid crystal display device according to the present invention is a liquid crystal display device that displays an image by switching between a reflective display mode and a transmissive display mode,
A light source side polarizing plate and an observer side polarizing plate;
A liquid crystal layer provided between the light source side polarizing plate and the observer side polarizing plate;
A light source provided behind the light source side polarizing plate;
Provided between the light source side polarizing plate and the liquid crystal layer, and reflects light that has entered from the observer side polarizing plate and passed through the liquid crystal layer, while exiting from the light source and illuminating the light source side polarizing plate. A transflective layer that transmits the transmitted light; and
Provided between the observer-side polarizing plate and the transflective layer, and modulates the light reflected by the transflective layer and passing through the liquid crystal layer so as to be emitted from the observer-side polarizing plate. An observer-side retardation plate;
Light that is provided between the light source side polarizing plate and the semi-transmissive reflective layer and transmits the light transmitted through the semi-transmissive reflective layer and the liquid crystal layer and the observer-side phase difference plate from the observer-side polarizing plate. A light source side retardation plate that modulates the light so as to be emitted;
Provided between the observer-side polarizing plate and the transflective layer and diffuses the light reflected by the transflective layer in the reflective display mode, while transflective in the transmissive display mode A light diffusing and transmitting layer that transmits the reflection layer and transmits the light passing through the liquid crystal layer and the observer-side retardation plate while preventing diffusion;
It is characterized by having.

  The transflective liquid crystal display device according to the present invention diffuses light reflected by the transflective layer between the transflective layer and the observer-side polarizing plate in the reflective display mode while transmitting the light. In the display mode, there is provided a light diffusing transmissive layer that transmits the transflective layer through the liquid crystal layer and the viewer side retardation plate while preventing diffusion.

  Therefore, when an image is displayed in the reflective display mode in the transflective liquid crystal display device according to the present invention, the light incident from the observer side polarizing plate is diffused by the light diffusing and transmissive layer, and then the observer side position. The light passes through the phase difference plate and the liquid crystal layer, and is reflected by the transflective layer. The light reflected by the transflective layer passes through the liquid crystal layer and the observer-side retardation plate, and is further diffused by the light diffusing and transmitting layer, and is emitted from the observer-side polarizing plate. Therefore, it is possible to realize a transflective liquid crystal display device capable of performing reflective display with a wide viewing angle and good visibility without directivity of light emitted from the observer-side polarizing plate.

  In addition, when an image is displayed in the transmission mode in the transflective liquid crystal display device according to the present invention, the light emitted from the light source includes a light source side polarizing plate, a light source side retardation plate, a transflective layer, After passing through the liquid crystal layer and the observer-side retardation plate, the light enters the light diffusion transmission layer. The light incident on the light diffusing and transmitting layer passes through the light diffusing and transmitting layer without being diffused by the light diffusing and transmitting layer. Therefore, the light emitted from the light source is not excessively diffused, and a transflective liquid crystal display device capable of transmissive display with high front luminance and high contrast can be realized.

  In the present invention, the light diffusing and transmitting layer may be composed of a polymer dispersed liquid crystal layer.

  According to this configuration, switching between the transmissive display mode and the reflective display mode can be easily performed by controlling the voltage applied to the polymer-dispersed liquid crystal layer. Therefore, it is possible to realize a transflective liquid crystal display device that does not require a complicated mechanism for controlling the light diffusion / transmission layer, is easy to manufacture, and has good operability.

  In the present invention, the polymer-dispersed liquid crystal layer, which is a light diffusive transmissive layer, diffuses light reflected by the semi-transmissive reflective layer in the reflective display mode, while transflective in the transmissive display mode. A liquid crystal contained in the light diffusing and transmitting layer is applied by applying a predetermined voltage to the light diffusing and transmitting layer so that the light passing through the layer and passing through the liquid crystal layer and the observer side retardation plate is transmitted while preventing diffusion. It is preferable to have a drive circuit for controlling the orientation direction of molecules.

  According to this configuration, the drive circuit for controlling the alignment direction of the liquid crystal molecules contained in the light diffusion / transmission layer is provided independently of the drive of the display liquid crystal.

  Therefore, even while the display liquid crystal is being driven, the polymer dispersed liquid crystal layer can be driven independently of the display liquid crystal. Therefore, regardless of the display state of the display liquid crystal, it is possible to arbitrarily switch between the reflective display mode and the transmissive display mode of the transflective liquid crystal display device.

  Moreover, in this invention, you may be comprised so that the orientation direction of the liquid crystal molecule contained in the polymer dispersion-type liquid crystal layer which is a light-diffusion transmission layer can be controlled continuously.

  According to this configuration, the degree of light diffusion of the polymer dispersed liquid crystal layer can be continuously adjusted by continuously controlling the alignment direction of the liquid crystal molecules contained in the polymer dispersed liquid crystal layer.

  As the alignment direction of the liquid crystal molecules contained in the polymer-dispersed liquid crystal layer becomes disordered, the degree of diffusion of light reflected from the transflective layer and emitted from the observer-side polarizing plate increases. Therefore, the transflective liquid crystal display device has a wide viewing angle and a low front luminance. On the other hand, as the liquid crystal molecules contained in the polymer-dispersed liquid crystal layer are aligned, the degree of diffusion of light reflected by the transflective layer and emitted from the observer-side polarizing plate becomes weaker. Therefore, the viewing angle of the transflective liquid crystal display device is narrow and the front luminance is increased.

  Therefore, according to this configuration, it is possible to realize a transflective liquid crystal display device capable of arbitrarily adjusting the viewing angle and the front luminance.

  As described above, according to the present invention, when the image is displayed in the reflective display mode, the light reflected by the transflective film is diffused. On the other hand, when the image is displayed in the transmissive display mode, the light emitted from the light source is diffused. And a transflective layer that has a function of transmitting and preventing light transmission, and is easy to manufacture, and has a wide viewing angle and good visibility, and a transmissive display mode with high brightness and high contrast. Can be displayed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view of a transflective liquid crystal display device 1 according to an embodiment of the present invention.

  FIG. 2 is a cross-sectional view showing an optical path of light incident from the observer-side polarizing plate 100 when the transflective liquid crystal display device 1 displays an image in the reflective display mode.

  FIG. 3 is a cross-sectional view showing an optical path of light emitted from the light source 190 when the transflective liquid crystal display device 1 displays an image in the transmissive display mode.

  The transflective liquid crystal display device 1 includes an observer side polarizing plate 100 and a light source side polarizing plate 180. The observer side polarizing plate 100 and the light source side polarizing plate 180 have a function of transmitting only a specific polarization component with respect to incident light.

  An STN liquid crystal cell 140 for displaying an image is provided between the observer side polarizing plate 100 and the light source side polarizing plate 180. The STN liquid crystal cell 140 includes a substrate 130, a transparent electrode 141, an alignment film 142, an STN liquid crystal layer 143, an alignment film 144, a transparent electrode 145, an overcoat layer 146, a color filter 147, and transflective reflection. A film 150 and a substrate 160 are provided.

  The transparent electrode 141 and the transparent electrode 145 are provided so as to sandwich the STN liquid crystal layer 143 sandwiched between the alignment film 142 and the alignment film 144. The transparent electrode 141 and the transparent electrode 145 are made of, for example, indium tin oxide (hereinafter sometimes abbreviated as “ITO”) in which 1 to 5 weight percent of tin oxide is added to indium oxide, and the STN liquid crystal. The layer 143 has a function of applying a voltage.

  The alignment film 142 and the alignment film 144 are provided so as to sandwich the STN liquid crystal layer 143. The alignment film 142 and the alignment film 144 are made of, for example, a thin film such as polyimide that is rubbed by rubbing in a certain direction with a cloth or the like, and has a function of aligning rod-like liquid crystal molecules in the rubbing direction.

  The STN liquid crystal cell 140 is configured so that the alignment film 142 and the alignment film 144 have a rubbing direction twisted by about 180 to 270 °. Accordingly, the liquid crystal molecules dispersed in the STN liquid crystal layer 143 have a twist structure of about 180 to 270 °.

  The overcoat layer 146 is made of, for example, an acrylic resin, and has an effect of flattening the unevenness present on the surface of the color filter 147 and making the rising of the liquid crystal display uniform.

  A light source 190 is provided behind the light source side polarizing plate 180. The light source 190 is configured by, for example, a direct type backlight, an edge light type backlight, or the like, and is uniform over the entire STN liquid crystal cell 140 when the transflective liquid crystal display device 1 displays an image in the transmissive display mode. It has a function of supplying light.

  Between the light source side polarizing plate 180 and the STN liquid crystal layer 143, a transflective layer 150, a substrate 160, and a retardation plate 170 are provided.

  The phase difference plate 170 has a function of performing phase modulation so that light emitted from the light source 190 and transmitted through the STN liquid crystal cell 140 is emitted from the observer-side polarizing plate 100.

  The transflective layer 150 is, for example, a metal total reflection layer made of aluminum, silver, or the like provided with a light transmission opening that penetrates the metal total reflection layer in the thickness direction, or a metal thin film such as aluminum or silver It is formed by a half mirror or the like.

  Therefore, the semi-transmissive reflective layer 150 reflects the light incident from the observer side polarizing plate 100 and passing through the STN liquid crystal layer 143, while transmitting the light emitted from the light source 190 and transmitted through the light source side polarizing plate 180. .

  Therefore, by using the transflective layer 150, it is possible to realize the transflective liquid crystal display device 1 that can display an image by switching between the transmissive display mode and the reflective display mode.

  Between the observer-side polarizing plate 100 and the STN liquid crystal cell 140, a polymer dispersion type liquid crystal cell 110 that is a light diffusion transmission layer and a retardation plate 120 are provided.

  The phase difference plate 120 has a function of performing phase modulation so that the light reflected by the transflective layer 150 and transmitted through the STN liquid crystal layer 143 is emitted from the observer-side polarizing plate 100.

  The polymer dispersion type liquid crystal cell 110 has a function as a light diffusion / transmission layer, and includes a substrate 111, a substrate 115, a polymer dispersion type liquid crystal layer 113 provided between the substrate 111 and the substrate 115, and a polymer dispersion type. A transparent electrode 112 and a transparent electrode 114 are provided so as to sandwich the liquid crystal layer 113.

  The substrate 111, the substrate 115, and the above-described substrate 130 and substrate 160 are made of a light-transmitting substrate such as a glass substrate or a resin substrate, for example. When a resin substrate is used, a thin and flexible transflective liquid crystal display device 1 can be realized.

  The polymer-dispersed liquid crystal layer 113 is a layer in which liquid crystal molecules 116 are dispersed in a uniaxial polymer 117.

  The liquid crystal molecules 116 are formed so as to have the same refractive index as that of the polymer 117 when aligned in the electrode direction, and to have a refractive index different from that of the polymer 117 when not aligned in the electrode direction.

  When no voltage is applied, the liquid crystal molecules 116 are present in a random direction in the polymer 117, and the refractive indexes of the polymer 117 and the liquid crystal molecules 116 are different. Therefore, the polymer dispersed liquid crystal layer 113 has a function of diffusing incident light.

  On the other hand, in a state where a predetermined voltage is applied, the liquid crystal molecules 116 are aligned in the electrode direction, and the refractive index of the polymer 117 and the refractive index of the liquid crystal molecules 116 are equal. Therefore, the light incident on the polymer dispersed liquid crystal layer 113 is transmitted without being diffused by the polymer dispersed liquid crystal layer 113.

  Accordingly, when the polymer dispersion type liquid crystal cell 110 is in the reflective display mode, as shown in FIG. 2, by applying no voltage to the polymer dispersion type liquid crystal cell 110, the light reflected by the transflective layer 150 is diffused. On the other hand, in the transmissive display mode, as shown in FIG. 3, by applying a predetermined voltage to the polymer dispersed liquid crystal cell 110, the transflective layer 150, the STN liquid crystal cell 140, and the observer The light transmitted through the side phase difference plate 120 can be transmitted while being prevented from diffusing.

  Therefore, by using the polymer-dispersed liquid crystal cell 110 that is a light diffusion / transmission layer, it is possible to display an image in a reflective display mode with a wide viewing angle and good visibility and a transmissive display mode with high front luminance and high contrast. A transflective semi-reflective liquid crystal display device 1 can be provided.

  As described above, the polymer-dispersed liquid crystal cell 110 can easily switch between the reflective display mode and the transmissive display mode of the transflective liquid crystal display device 1 by controlling the applied voltage.

  Therefore, by using the polymer dispersion type liquid crystal cell 110 as the light diffusing and transmitting layer, it is possible to realize the transflective liquid crystal display device 1 that can easily switch between the reflective display mode and the transmissive display mode. .

  The polymer dispersion type liquid crystal cell 110 is provided with a drive circuit 101 independent of the drive circuit 102 of the STN liquid crystal cell 140 which is a display liquid crystal.

  Therefore, the polymer dispersion type liquid crystal cell 110 can be controlled separately from the STN liquid crystal cell 140 which is a display liquid crystal. Therefore, the transflective liquid crystal display device 1 that can arbitrarily switch between the reflective display mode and the transmissive display mode regardless of the display state of the STN liquid crystal cell 140 can be realized.

  In addition, the drive circuit 101 is configured to be able to continuously control the voltage applied to the polymer dispersion type liquid crystal cell 110, and the transflective liquid crystal display device 1 is a polymer dispersion type liquid crystal cell that is a diffuse transmission layer. 110 is configured such that the alignment direction of the liquid crystal molecules 116 included in 110 can be continuously controlled.

  By continuously controlling the orientation direction of the liquid crystal molecules 116, the degree of light diffusion by the polymer dispersion type liquid crystal cell 110 can be adjusted, and the viewing angle and front luminance of the transflective liquid crystal display device 1 can be continuously adjusted. Therefore, the transflective liquid crystal display device 1 that can be adjusted automatically can be realized.

  Hereinafter, the viewing angle and front luminance of the transflective liquid crystal display device 1 are controlled by continuously controlling the voltage applied to the polymer dispersed liquid crystal cell 110 and continuously controlling the orientation direction of the liquid crystal molecules 116. The principle that can be arbitrarily adjusted will be described.

  FIG. 4 is a cross-sectional view of the polymer dispersed liquid crystal cell 110 in a state where no voltage is applied to the drive circuit 101.

  FIG. 5 is a cross-sectional view of the polymer-dispersed liquid crystal cell 110 in a state where the voltage V1 is applied to the drive circuit 101. FIG.

  FIG. 6 is a cross-sectional view of the polymer dispersed liquid crystal cell 110 in a state where the voltage V0 is applied to the drive circuit 101. As shown in FIG.

  In a state where no voltage is applied to the polymer dispersion type liquid crystal layer 113, the liquid crystal molecules 116 in the polymer dispersion type liquid crystal layer 113 are randomly dispersed as shown in FIG. For this reason, a difference in refractive index occurs between the liquid crystal molecules 116 and the polymer 117. Therefore, light incident on the polymer dispersion type liquid crystal cell 110 is diffused by the polymer dispersion type liquid crystal layer 113. Therefore, the transflective liquid crystal display device 1 when no voltage is applied has a wide viewing angle.

  When the voltage applied to the polymer dispersed liquid crystal layer 113 is gradually increased, the liquid crystal molecules 116 are gradually aligned in the electrode direction. For this reason, the refractive index difference between the liquid crystal molecules 116 and the polymer 117 is smaller than when no voltage is applied.

  Therefore, as the voltage applied to the polymer dispersed liquid crystal layer 113 is gradually increased, the degree of diffusion of light incident on the polymer dispersed liquid crystal cell 110 decreases. Accordingly, the viewing angle of the transflective liquid crystal display device 1 becomes smaller than when no voltage is applied, and the front luminance becomes larger than when no voltage is applied.

  For example, as shown in FIG. 5, the viewing angle θb when the voltage V1 (the voltage V1 is smaller than the voltage V0 sufficient for aligning the liquid crystal molecules 116) is applied to the polymer-dispersed liquid crystal layer 113 is As shown in FIG. 4, it is smaller than the viewing angle θa when no voltage is applied.

  When the voltage applied to the polymer-dispersed liquid crystal layer 113 is increased to a voltage V0 sufficient to align the liquid crystal molecules 116, the liquid crystal molecules 116 are completely aligned in the electrode direction as shown in FIG. And the polymer 117 have the same refractive index. Therefore, the polymer dispersion type liquid crystal cell 110 transmits the light incident on the polymer dispersion type liquid crystal cell 110 while preventing diffusion.

  As described above, by continuously controlling the voltage applied to the polymer dispersion type liquid crystal layer 113 and continuously controlling the alignment state of the liquid crystal molecules 116, the viewing angle and the front luminance can be arbitrarily controlled. The transflective liquid crystal display device 1 can be realized.

  Below, the manufacturing method of the transflective liquid crystal display device 1 is demonstrated.

  First, the transflective layer 150 is formed by forming a metal thin film made of, for example, aluminum or silver on a light-transmitting substrate 160 made of, for example, glass or resin by a film forming method such as sputtering. .

  Next, a color filter layer 147 is formed on the substrate 160 on which the transflective layer 150 is formed by, for example, an electrodeposition method or the like, and then an overcoat layer 146 made of, for example, an acrylic resin or the like is formed.

  Next, a transparent conductive film made of, for example, ITO (indium tin oxide) or the like is formed on the overcoat layer 146 by a film forming method such as a sputtering method, and pattern processing is performed by a photolithography technique or the like. An electrode 145 is formed.

  Next, an alignment film 144 is formed on the transparent electrode 145 by, for example, a roll coater method, and a rubbing process is performed.

  Next, for example, the transparent electrode 141 and the alignment film 142 are sequentially formed on the light-transmitting substrate 130 made of glass, resin, or the like, like the substrate 160, and then a rubbing process is performed.

  Next, the substrate 130 and the substrate 160 that constitute a transparent electrode or the like are bonded to face each other, and STN liquid crystal is vacuum injected between the alignment film 142 and the alignment film 144 to form the STN liquid crystal layer 143. .

  Next, a manufacturing method of the polymer dispersion type liquid crystal cell 110 will be described.

  First, for example, a transparent conductive film such as ITO (indium tin oxide) is formed on a substrate 111 made of glass or resin by a film forming method such as sputtering, and pattern processing is performed by a photolithography technique or the like. Thus, the transparent electrode 112 is formed.

  Next, the transparent electrode 114 made of ITO (indium tin oxide) or the like is formed on the substrate 115 made of glass or resin by the same method, for example.

  Next, the substrate 111 and the substrate 115 on which the transparent electrode is formed are bonded to face each other, and a polymer-dispersed liquid crystal solution composed of the ultraviolet curable polymer 117 and the liquid crystal molecules 116 is interposed between the transparent electrode 112 and the transparent electrode 114. Then, the polymer dispersion type liquid crystal cell 110 is formed by irradiating with ultraviolet rays to form the polymer dispersion type liquid crystal layer 113.

  A laminate composed of the polymer dispersion type liquid crystal cell 110 and the STN liquid crystal cell 140 prepared as described above, an observer-side polarizing plate 100, a light source-side polarizing plate 180, observer-side retardation plates 120 and 170, The light source 190 and the light source 190 are pasted together in the order shown in FIG. 1 to produce the transflective liquid crystal display device 1.

  In the present embodiment, the light diffusing and transmitting layer is composed of the polymer dispersion type liquid crystal cell 110, but the light diffusing and transmitting layer diffuses the light reflected by the transflective layer 150 in the reflective display mode. In the transmissive display mode, there is no limitation as long as the light can be transmitted while being prevented from diffusing through the semi-transmissive reflective layer 150 and the STN liquid crystal layer 143 and the observer-side retardation plate 120. Is not to be done.

  In this embodiment, the observer-side retardation plate 120 is provided between the polymer dispersion type liquid crystal cell 110 and the STN liquid crystal cell 140. However, the present invention is not limited to this configuration. The plate 120 may be provided between the observer side polarizing plate 100 and the polymer dispersion type liquid crystal cell 110.

  In that case, the substrate 115 and the substrate 130 may be shared to form a single substrate. Thereby, the effect of parallax due to the substrate thickness can be suppressed, and a transflective liquid crystal display device capable of displaying a clearer image can be realized.

  In the present embodiment, the polymer dispersion type liquid crystal cell 110 is provided between the observer side polarizing plate 100 and the observer side retardation plate 120. However, the present invention is not limited to this configuration. The liquid crystal cell 110 may be interposed anywhere between the transflective layer 150 and the viewer-side polarizing plate 100, for example, of course, may be interposed between the substrate 130 and the transparent electrode 141. Absent.

  Further, the present embodiment relates to the color transflective liquid crystal display device 1 having the STN liquid crystal cell 140 as a display liquid crystal layer. However, the present invention is not limited to this, and the present invention is not limited to black and white. The present invention can also be applied to a transflective liquid crystal display device having an STN liquid crystal layer, a transflective liquid crystal display device having an active matrix driving liquid crystal layer using a switching element such as a TFT or MIM, and the like. it can.

1 is a cross-sectional view of a transflective liquid crystal display device 1 according to an embodiment of the present invention. It is sectional drawing which shows the optical path of the light which injects from the observer side polarizing plate 100 in the case of displaying an image in the transflective liquid crystal display device 1 in the reflective display mode. It is sectional drawing which shows the optical path of the light radiate | emitted from the light source 190 in the case of displaying an image by the transflective liquid crystal display device 1 in a transmissive display mode. 2 is a cross-sectional view of a polymer dispersed liquid crystal cell 110 in a state where no voltage is applied to a drive circuit 101. FIG. 2 is a cross-sectional view of a polymer dispersed liquid crystal cell 110 in a state where a voltage V1 is applied to a drive circuit 101. FIG. 2 is a cross-sectional view of a polymer dispersed liquid crystal cell 110 in a state where a voltage V0 is applied to a drive circuit 101. FIG. It is sectional drawing of the conventional transflective liquid crystal display device 2. FIG. It is sectional drawing of the transflective liquid crystal display device 3 which has the conventional light-diffusion layer 304. FIG.

Explanation of symbols

1, 2, 3 Transflective liquid crystal display device 100, 200 Observer side polarizing plate 101, 102 Drive circuit 110 Polymer dispersed liquid crystal cell 111, 115, 130, 160, 230, 260 Substrate 112, 114, 141, 145 Transparent electrode 113 Polymer dispersion type liquid crystal layer 116 Liquid crystal molecule 117 Polymer 120 Observer side retardation plate 140, 240 STN liquid crystal cell 142, 144 Alignment film 143 STN liquid crystal layer 146 Overcoat layer 147 Color filter layer 150, 250 Transflective reflection Layer 170 Light source side retardation plate 180, 280 Light source side polarizing plate 190, 290, 308 Light source 220, 270, 302 Phase difference plate 300 Hard coat protective film with antireflection treatment 301 Light absorbing polarizing film 303 Liquid crystal cell 304 Light diffusion layer 305 Reflective polarizing layer 306 Prism sheet 307 Light diffusion sheet

Claims (4)

A liquid crystal display device that displays an image by switching between a reflective display mode and a transmissive display mode,
A light source side polarizing plate and an observer side polarizing plate;
A liquid crystal layer provided between the light source side polarizing plate and the observer side polarizing plate;
A light source provided behind the light source side polarizing plate;
Provided between the light source side polarizing plate and the liquid crystal layer, and reflects light that has entered from the observer side polarizing plate and passed through the liquid crystal layer, while exiting from the light source and illuminating the light source side polarizing plate. A transflective layer that transmits the transmitted light; and
Provided between the observer-side polarizing plate and the transflective layer, and modulates the light reflected by the transflective layer and passing through the liquid crystal layer so as to be emitted from the observer-side polarizing plate. An observer-side retardation plate;
Provided between the light source side polarizing plate and the transflective layer, and transmits the light transmitted through the transflective layer and passing through the liquid crystal layer and the observer side retardation plate from the observer side polarizing plate. A light source side retardation plate that modulates the light so as to be emitted;
Provided between the observer-side polarizing plate and the transflective layer, and diffuses the light reflected by the transflective layer in the reflective display mode, while translucent in the transmissive display mode A light diffusing and transmitting layer that transmits the reflection layer and transmits the light passing through the liquid crystal layer and the observer-side retardation plate while preventing diffusion;
A liquid crystal display device. The liquid crystal display device according to claim 1,
A liquid crystal display device in which the light diffusion / transmission layer is composed of a polymer-dispersed liquid crystal layer. The liquid crystal display device according to claim 2,
The polymer-dispersed liquid crystal layer, which is the light diffusing transmissive layer, diffuses the light reflected by the semi-transmissive reflective layer in the reflective display mode, while transmitting the semi-transmissive reflective layer in the transmissive display mode. Then, a predetermined voltage is applied to the light diffusing and transmitting layer so that the light passing through the liquid crystal layer and the observer side retardation plate is transmitted while being prevented from being diffused. A liquid crystal display device having a drive circuit for controlling the alignment direction of liquid crystal molecules. The liquid crystal display device according to claim 2,
The liquid crystal display device comprised so that the orientation direction of the liquid crystal molecule contained in the said polymer dispersion-type liquid crystal layer which is the said light diffusive transmission layer was continuously controllable.

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