JP4496874B2 - Transflective liquid crystal display device and electronic device equipped with the same - Google Patents

Description

  The present invention relates to a transflective liquid crystal display having a reflective display area for displaying by reflecting incident light from the outside and a transmissive display area for transmitting light from a light source at the back. The present invention relates to a device and an electronic device on which the device is mounted.

  2. Description of the Related Art Conventionally, a reflection type liquid crystal display device that has a reflection plate inside the device, reflects incident light from the outside by the reflection plate, and is used as a display light source, and does not require a backlight as a light source, and a light source A transmissive liquid crystal display device having a backlight is known.

  A reflective liquid crystal display device does not require a backlight which is essential for a transmissive liquid crystal display device, and thus can achieve low power consumption, thinning, and light weight, and is mainly used for portable terminals. On the other hand, since the transmissive liquid crystal display device uses a backlight as a light source, it has excellent visibility even in a place where ambient light is dark.

  Therefore, as a liquid crystal display device having the advantages of both a reflective liquid crystal display device and a transmissive liquid crystal display device, as shown in a cross section in FIG. 7, both the reflective region 5 and the transmissive region 6 are included in one pixel (one pixel). A technique relating to a transflective liquid crystal display device having the above has been disclosed (for example, see Patent Document 1 (Japanese Patent No. 2955277)). In the liquid crystal display device shown in FIG. 7, the incident light travels back and forth through the liquid crystal layer in the reflective region 5, and the incident light passes through the liquid crystal layer in the transmissive region 6, thereby causing a light path difference in the liquid crystal layer. In order to prevent this, an insulating layer 8 is provided under the transmissive electrode 7 in the reflective region 5, and a reflective plate 9 is disposed under the insulating layer 8, and the thickness dr of the liquid crystal layer in the reflective region 5 and the transmissive region 6 By providing a difference in the thickness df of the liquid crystal layer, the emitted light intensity due to the difference in retardation in both regions is optimized.

  In this way, the transflective liquid crystal display device can be used as a reflective liquid crystal display device by turning off the backlight when ambient light is bright by providing a transmissive display region and a reflective display region on the pixel electrode. It exhibits the characteristics of a reflective liquid crystal display device with low power consumption. On the other hand, when ambient light is dark, it can be used as a transmissive liquid crystal display device by turning on the backlight. It exhibits the characteristics of a transmissive liquid crystal display device, such as improved visibility.

  By the way, as a liquid crystal display device, a vertical electric field drive system that performs display by rotating the direction of the molecular axis of an aligned liquid crystal molecule (called “director”) in a plane orthogonal to the surface of the substrate, There is a lateral electric field drive system in which display is performed by rotating in a plane parallel to the surface.

  The vertical electric field drive type transmissive liquid crystal display device has poor viewing angle characteristics as compared with the horizontal electric field drive type. However, in the reflective display region using the same method, the traveling direction of the incident light and the reflected light is opposite to the direction of the main refractive index of the liquid crystal molecules (optical axis direction), and the symmetry is excellent. Therefore, the birefringence amounts of the incident light and the outgoing light are canceled each other and the amount of change becomes small, and an excellent viewing angle characteristic can be obtained.

  In view of this, it has been proposed to use a lateral electric field driving method for the transmissive display region with the aim of further improving the viewing angle characteristics of the transflective liquid crystal display device (for example, Japanese Patent Laid-Open No. 11-167109). )reference.).

  However, in the technique disclosed in Patent Document 2, when the transflective liquid crystal display device shown in FIG. 7 is employed, the reflective display area 5 is normally white, but the transmissive display area. 6 is normally black or normally white in the reflective display area 5, but normally black in the transmissive display area 6. Therefore, there is a problem that it cannot be used as a display device. This will be described in detail with reference to the drawings.

  FIG. 8 is a diagram in the case where the transflective liquid crystal display device of FIG. 8A shows the optical arrangement, FIG. 8B shows the arrangement angle of the polarizing plate and the liquid crystal layer when viewed from the counter substrate 12, and FIG. 8C shows the operation thereof.

  As shown in FIG. 8A, the transflective liquid crystal display device 50 includes a lower substrate 11, a counter substrate 12, a liquid crystal layer 13 sandwiched between both substrates, and a lower substrate 11. The lower side substrate 11 and the opposite side substrate 12 include the polarizing plates 21a and 21b on the outer sides of the transparent insulating substrates 22a and 22b, respectively. Although omitted in FIG. 8A for simplification, a horizontal alignment film is formed on the surfaces of the lower substrate 11 and the opposite substrate 12 that sandwich the liquid crystal layer 13 in contact with the liquid crystal layer 13.

  A first insulating film 8 a is formed on the liquid crystal layer 13 side of the lower substrate 11. In the reflective display area 5, a second insulating film 8 b is formed on the first insulating film 8 a, a reflecting plate 9 is formed on the second insulating film 8 b, and a third is formed on the reflecting plate 9. The lateral electric field drive electrode 7 is formed on the third insulating film 8c. The horizontal electric field driving electrode 7 is formed of a pixel electrode 27 and a common electrode 26 which are parallel to each other, and drives the liquid crystal layer 13 by an electric field formed between the pixel electrode 27 and the common electrode 26. In the transmissive display region 6, the pixel electrode 27 and the common electrode 26 are formed in parallel with each other on the first insulating film 8 a, and the liquid crystal layer 13 is formed by an electric field formed between the pixel electrode 27 and the common electrode 26. To drive. The second insulating film 8b and the third insulating film 8c are provided to adjust the difference in thickness of the liquid crystal layer 13 between the transmissive display area 6 and the reflective display area 5.

  As shown in FIG. 8B, when no voltage is applied between the common electrode 26 and the pixel electrode 27, the arrangement angle of the polarizing plate 21a on the lower side of the reflective display area 5 and the transmissive display area 6 is set to 0. In this case, the arrangement angle of the opposing polarizing plate 21b is set to 90 degrees, and the arrangement angle of the liquid crystal layer 13 is set to 90 degrees.

  The operation of the transflective liquid crystal display device 50 at this time is shown in FIG. The reflective display area 5 operates as follows. In a state in which no voltage is applied between the pixel electrode 27 and the common electrode 26, the linearly polarized light with the arrangement angle of 90 degrees transmitted through the polarizing plate 21b remains the linearly polarized light with the arrangement angle of 90 degrees even though it passes through the liquid crystal layer 13. Then, the light is reflected by the reflecting plate 9, passes through the liquid crystal layer 13 again, and passes through the polarizing plate 21b while being linearly polarized light having an arrangement angle of 90 degrees, resulting in white display. In a state where a voltage is applied between the pixel electrode 27 and the common electrode 26, the arrangement angle of the liquid crystal layer 13 changes to 45 degrees. Therefore, the linearly polarized light having an arrangement angle of 90 degrees transmitted through the polarizing plate 21b is transmitted through the liquid crystal layer 13 to become clockwise circularly polarized light, reflected by the reflecting plate 9, and converted into counterclockwise circularly polarized light. Since the light is transmitted and becomes linearly polarized light with an arrangement angle of 0 degrees, it cannot be transmitted through the polarizing plate 21b, and a black display is obtained. That is, it becomes normally white.

  On the other hand, the transmissive display area 6 operates as follows. In a state where no voltage is applied to the liquid crystal layer 13, the linearly polarized light (arrangement angle 0 degree) transmitted through the polarizing plate 21 a remains linearly polarized with an arrangement angle of 0 degree even though it passes through the liquid crystal layer 13. The light cannot be transmitted through the polarizing plate 21b and is displayed in black. In a state where a voltage is applied to the liquid crystal layer 13, the arrangement angle of the liquid crystal 13 changes to 45 degrees. Therefore, the linearly polarized light (arrangement angle 0 degree) transmitted through the polarizing plate 21a is transmitted through the liquid crystal layer 13 to become linearly polarized light with an arrangement angle of 90 degrees, and is transmitted through the polarizing plate 21b with an arrangement angle of 90 degrees to display white. Become. That is, it becomes normally black.

  In addition, although it is well-known about the change of the polarization by a liquid crystal, it supplements description. The change in polarization due to the liquid crystal is determined by the value of (Δn × d). Δn is the refractive index anisotropy, and d is the thickness of the liquid crystal. When the value of (Δn × d) is adjusted to a quarter wavelength of incident polarized light, it changes to circularly polarized light when the incident polarized light is linearly polarized light, and to linearly polarized light when the incident polarized light is circularly polarized light. In addition, when the value of (Δn × d) is adjusted to a half wavelength of incident light, the angle between the arrangement angle of the liquid crystal and the arrangement angle of linearly polarized light incident on the liquid crystal is φ, After passing through the liquid crystal layer, the arrangement angle changes to 2φ.

  As described above, the transflective liquid crystal display device 50 has a problem that the reflective display area 5 is normally white but the transmissive display area 6 is normally black.

  Next, consider a transflective liquid crystal display device 51 configured to be normally black in the reflective display region 5. FIGS. 9A to 9C are diagrams showing a transflective liquid crystal display device in which the arrangement angle of the liquid crystal is set to 45 degrees in a state where no voltage is applied to the liquid crystal, and FIG. (B) shows the arrangement angle of the polarizing plate and the liquid crystal layer when viewed from the counter substrate side, and (c) shows the operation thereof. The difference between the transflective liquid crystal display device shown in FIG. 9A and the transflective liquid crystal display device shown in FIG. 8A is only the arrangement angle of the liquid crystal, and other optical arrangements are shown in FIG. This is the same as the transflective liquid crystal display device shown in FIG.

  As shown in FIG. 9C, the reflective display area 5 operates as follows. In a state where no voltage is applied between the pixel electrode 27 and the common electrode 26, the linearly polarized light having an arrangement angle of 90 degrees transmitted through the polarizing plate 21b is transmitted through the liquid crystal 13a to become clockwise circularly polarized light. The liquid crystal 13a is further transmitted through the counterclockwise circularly polarized light and becomes linearly polarized light with an arrangement angle of 0 degree, and thus cannot be transmitted through the polarizing plate 21b, resulting in black display. In a state where a voltage is applied between the pixel electrode 27 and the common electrode 26, the arrangement angle of the liquid crystal 13a changes to 90 degrees. Therefore, the linearly polarized light having an arrangement angle of 90 degrees that has been transmitted through the polarizing plate 21b remains the linearly polarized light having an arrangement angle of 90 degrees even though it has been transmitted through the liquid crystal 13a, is reflected by the reflecting plate 9, and is again transmitted through the liquid crystal 13a. Since the linearly polarized light having an angle of 90 degrees is transmitted through the polarizing plate 21b, white display is obtained. That is, it becomes normally black.

  On the other hand, the transmissive display area 6 operates as follows. In a state where no voltage is applied to the liquid crystal 13a, the linearly polarized light having an arrangement angle of 0 degrees transmitted through the polarizing plate 21a is transmitted through the liquid crystal 13a to become linearly polarized light having an arrangement angle of 90 degrees and transmitted through the polarizing plate 21b having an arrangement angle of 90 degrees. And it becomes white display. When voltage is applied to the liquid crystal 13a, the arrangement angle of the liquid crystal 13a changes to 90 degrees. Therefore, the linearly polarized light having the arrangement angle of 0 ° transmitted through the polarizing plate 21a remains the linearly polarized light having the arrangement angle of 0 ° even though the liquid crystal 13a is transmitted, and cannot be transmitted through the polarizing plate 21b having the arrangement angle of 90 °. become. That is, it becomes normally white.

  As described above, the transflective liquid crystal display device 51 has a problem that the reflective display area 5 is normally black but the transmissive display area 6 is normally white.

  Further, consider a transflective liquid crystal display device 52 in which the reflective display area 5 is driven by a vertical electric field and only the transmissive display area 6 is driven by a horizontal electric field. FIG. 10 is a diagram showing a transflective liquid crystal display device in which the liquid crystal driving method in the reflective display region is a vertical electric field method. FIG. 10A shows the optical arrangement of the transflective liquid crystal display device 52, FIG. 10B shows the arrangement angle of the polarizing plate and the liquid crystal layer when viewed from the opposite substrate 12, and FIG. ).

  In the reflective display region 5 shown in FIG. 10A, the reflector 9 and the lateral electric field drive electrode 7 provided in the transflective liquid crystal display device shown in FIG. A transparent reflective pixel electrode 10 is provided on the second insulating film 8 b, and a transparent counter electrode 14 is provided at a position facing the reflective pixel electrode 10 of the opposing substrate 12. In the reflective display area 5 shown in FIG. 10A, a vertical electric field is formed between the reflective pixel electrode 10 and the counter electrode 14. The optical arrangement of the transmissive display area 6 in FIG. 10A is the optical arrangement of the transmissive display area 6 in FIG. 9A, and the polarizing plate 21a when viewed from the counter substrate 12 in FIG. 10B. , 21b and the liquid crystal 13a are disposed at the same angles as in FIGS.

  The operation of the reflective display area 5 of the transflective liquid crystal display device 52 will be described with reference to FIG. In a state where no voltage is applied between the reflective pixel electrode 10 and the counter electrode 14, the linearly polarized light having an arrangement angle of 90 degrees transmitted through the polarizing plate 21b is transmitted through the liquid crystal 13a to become clockwise circularly polarized light. The liquid crystal 13a is further transmitted through the counterclockwise circularly polarized light and becomes linearly polarized light with an arrangement angle of 0 degree, and thus cannot be transmitted through the polarizing plate 21b, resulting in black display. In a state where a voltage is applied between the reflective pixel electrode 10 and the counter electrode 14, the liquid crystal 13a rises in the vertical direction. Therefore, the linearly polarized light having an arrangement angle of 90 degrees transmitted through the polarizing plate 21b remains as the linearly polarized light having the arrangement angle of 90 degrees even though it has been transmitted through the liquid crystal 13a, and is reflected by the reflector 9 and transmitted again through the liquid crystal 13a. Since the linearly polarized light having an angle of 90 degrees is transmitted through the polarizing plate 21b, white display is obtained. That is, it becomes normally black. The operation of the transmissive display area 6 is the same as that in FIG. As described above, the transflective liquid crystal display device 52 also has a problem that the reflective display area 5 is normally black but the transmissive display area 6 is normally white.

  As described above, when the transmissive display region 6 is driven by a horizontal electric field, the reflective display region 5 is normally white, transmissive, regardless of whether the reflective display region 5 is driven by a horizontal electric field or a vertical electric field. The display area 6 becomes normally black, or the reflective display area 5 becomes normally black and the transmissive display area 6 becomes normally white. In order to force display, it is necessary to reverse the polarities of the image signal input to the reflective display area and the image signal input to the transmissive display area, resulting in great difficulty in device structure and signal processing. Bring.

  As a means for solving the above-mentioned problems, at least the transmissive display area is a lateral electric field drive system, and a half-wave plate is provided between the lower polarizing plate and the lower transparent insulating substrate. Such a transflective liquid crystal display device is disclosed in, for example, Japanese Patent Application Laid-Open No. 2003-344837.

  Hereinafter, a transflective liquid crystal display device will be described based on the technique disclosed in Patent Document 3 (Japanese Patent Laid-Open No. 2003-344837). FIG. 11 is a diagram showing a transflective liquid crystal display device disclosed in Patent Document 3 (Japanese Patent Laid-Open No. 2003-344837). 11A shows the optical arrangement, FIG. 11B shows the arrangement angle of the polarizing plate, the liquid crystal layer, and the half-wave plate when viewed from the opposite substrate 12, and FIG. 11C shows the operation thereof.

  As shown in FIG. 11A, the transflective liquid crystal display device 53 includes a lower substrate 11, a counter substrate 12, a liquid crystal layer 13 sandwiched between both substrates, and a lower substrate 11. It is formed from the arranged backlight 40.

  The lower substrate 11 is provided with a half-wave plate 29a and a polarizing plate 21a toward the outside with the transparent insulating substrate 22a as a base. The counter substrate 12 includes a transparent insulating substrate 22b as a base and a polarizing plate 21b on the outside.

  Although omitted in FIG. 11A for simplification, a horizontal alignment film is formed on the surface of the lower substrate 11 and the opposite substrate 12 that sandwich the liquid crystal layer 13 in contact with the liquid crystal layer 13.

  A first insulating film 8 a is formed on the liquid crystal layer 13 side of the lower substrate 11. In the reflective display area 5, a second insulating film 8 b is formed on the first insulating film 8 a, a reflecting plate 9 is formed on the second insulating film 8 b, and a third is formed on the reflecting plate 9. The lateral electric field drive electrode 7 is formed on the third insulating film 8c. The horizontal electric field drive electrode 7 is formed of a pixel electrode 27 and a common electrode 26 which are parallel to each other, and drives the liquid crystal 13 a by an electric field formed between the pixel electrode 27 and the common electrode 26. In the transmissive display region 6, the pixel electrode 27 and the common electrode 26 are formed in parallel with each other on the first insulating film 8 a, and the liquid crystal 13 a is formed by an electric field formed between the pixel electrode 27 and the common electrode 26. To drive. The second insulating film 8b and the third insulating film 8c are provided to adjust the difference in thickness of the liquid crystal layer 13 between the transmissive display area 6 and the reflective display area 5.

  As shown in FIG. 11B, in a state where no voltage is applied to the liquid crystal 13a, when the arrangement angle of the polarizing plate 21a on the lower side of the reflective display region 5 and the transmissive display region 6 is 0 degree, The arrangement angle of the polarizing plate 21b is set to 90 degrees, the arrangement angle of the liquid crystal 13a is set to 45 degrees, and the arrangement angle of the half-wave plate 29a is set to 135 degrees.

  FIG. 11C shows the operation of the liquid crystal display device 53 when set as described above. The reflective display area 5 operates as follows. In a state where no voltage is applied between the pixel electrode 27 and the common electrode 26, the linearly polarized light having an arrangement angle of 90 degrees transmitted through the polarizing plate 21b is transmitted through the liquid crystal 13a to become clockwise circularly polarized light. And is transmitted through the liquid crystal layer 13 to the left-handed circularly polarized light and becomes linearly polarized light with an arrangement angle of 0 degrees, and thus cannot be transmitted through the polarizing plate 21b, resulting in black display. Further, in a state where a voltage is applied between the pixel electrode 27 and the common electrode 26, the arrangement angle of the liquid crystal 13a changes to 90 degrees. Therefore, the linearly polarized light having an arrangement angle of 90 degrees transmitted through the polarizing plate 21b remains as the linearly polarized light having the arrangement angle of 90 degrees even though it has been transmitted through the liquid crystal 13a, and is reflected by the reflector 9 and transmitted again through the liquid crystal 13a. Since the linearly polarized light having an angle of 90 degrees is transmitted through the polarizing plate 21b, white display is obtained. That is, it becomes normally black.

  On the other hand, the transmissive display area 6 operates as follows. In a state where no voltage is applied to the liquid crystal 13a, the linearly polarized light with the arrangement angle of 0 degrees transmitted through the polarizing plate 21a becomes the linearly polarized light with the arrangement angle of 90 degrees when transmitted through the half-wave plate 29a, and the liquid crystal 13a is When transmitted, the arrangement angle is further rotated to become linearly polarized light with an arrangement angle of 0 degrees, and cannot pass through the polarizing plate 21b with an arrangement angle of 90 degrees, resulting in black display. Further, in a state where a voltage is applied between the pixel electrode 27 and the common electrode 26, the arrangement angle of the liquid crystal 13a is set to 90 degrees. In this state, the linearly polarized light having the arrangement angle of 0 degrees transmitted through the polarizing plate 21a becomes the linearly polarized light having the arrangement angle of 90 degrees when transmitted through the half-wave plate 29a, and the arrangement angle is rotated even though it is transmitted through the liquid crystal 13a. Without being transmitted through the polarizing plate 21b with an arrangement angle of 90 degrees as it is linearly polarized light with an arrangement angle of 90 degrees. That is, it becomes normally black.

  As described above, by providing the half-wave plate, the arrangement angle of the linearly polarized light is rotated by 90 degrees in the transmissive display region, and as a result, normally white is converted into normally black display characteristics. be able to. Thus, both the transmissive display area and the reflective display area are in the normally black mode, and a transflective liquid crystal display device having a wide viewing angle characteristic is provided without any special contrivance in the device structure or signal processing configuration. .

Japanese Patent No. 2955277 JP-A-11-167109 JP 2003-344837 A T.A. B. Jung and S.J. H. Lee, A Novel Transflective Display Associated with Ringe-Field Switching, SID 03 DIGEST, p. 592-p. 595

  However, even in the transflective liquid crystal display device disclosed in Patent Document 3 (Japanese Patent Laid-Open No. 2003-344837), the following display image quality problems still remain.

  In FIG. 12, the horizontal axis indicates the wavelength and the vertical axis indicates the transmittance. When black is displayed in the transmissive display area of the transflective liquid crystal display device disclosed in Patent Document 3 (Japanese Patent Laid-Open No. 2003-344837). It is a figure which shows the result of having performed simulation about the spectrum at the time of white display. As shown by the white display line 31, when the wavelength changes from 400 nm to about 500 nm, the transmittance increases from about 0.02 to about 0.3, gradually increases from about 500 nm to about 530 nm, and then gradually increases to about 600 nm. It was almost constant in the region of about 600 nm or more, and about 0.3 at 700 nm. As shown by the black display line 32, when the wavelength is changed from 400 nm to about 430 nm, the transmittance increases from about 0.01 to about 0.02, but then starts to decrease, and the transmittance is 0 in the region of about 480 nm or more. showed that. FIG. 13 is a diagram showing the result of a similar simulation performed on the reflective display area, with the horizontal axis representing wavelength and the vertical axis representing transmittance. As shown by the white display line 31, when the wavelength changes from 400 nm to about 500 nm, the transmittance increases from about 0.08 to about 0.32, gradually decreases from about 500 nm to about 600 nm, and then increases to about 600 nm or more. It rose slowly in the region, and showed about 0.35 at 700 nm. As shown by the black display line 32, when the wavelength is changed from 400 nm to about 430 nm, the transmittance increases from about 0.04 to about 0.08, but then starts to decrease, and at about 550 nm, the transmittance is 0. In the region of about 550 nm or more, it gradually increased, and at 700 nm, the transmittance was about 0.04. As shown in FIG. 12, the black display in the transmissive display area has a relatively low transmittance over almost the entire visible light range, and a good contrast is obtained. As shown, for black display in the reflective display region, the transmittance is increased at a wavelength shifted from the center wavelength. That is, there is a problem that an achromatic black display cannot be obtained in the display in the reflective display area.

  In addition to the technology disclosed in Patent Document 3 (Japanese Patent Laid-Open No. 2003-344837), for example, Non-Patent Document 1 (S.I.D.2003 International Symposium, Digest of Technical Papers p.592 to p.595), one each between the lower transparent insulating substrate 22a and the polarizing plate 21a and between the opposite transparent insulating substrate 21b and the polarizing plate 21b. A technique for realizing good black display over a wide wavelength region by disposing the half-wave plates 29a and 29b is disclosed.

  Transflective liquid crystal display constructed based on the technology disclosed in Non-Patent Document 1 (S.I.D.2003 International Symposium, Digest of Technical Papers, p.592-p.595) The device 54 will be described. FIG. 14 is a diagram in which a half-wave plate is disposed between the polarizing plate 21b and the transparent insulating substrate 22b of the transflective liquid crystal display device shown in FIG. The optical arrangement of the transflective liquid crystal display device 54 is shown in FIG. 14A, and the arrangement angle of the polarizing plate, the liquid crystal layer, and the half-wave plate when viewed from the opposite substrate 12 is shown in FIG. The operation is shown in FIG.

  As shown in FIG. 14B, in the state where no voltage is applied to the liquid crystal 13a, when the arrangement angle of the polarizing plate 21a on the lower side of the reflective display region 5 and the transmissive display region 6 is 75 degrees, The arrangement angle of the polarizing plate 21b is 15 degrees, the arrangement angle of the liquid crystal 13a is 90 degrees, the arrangement angle of the lower half-wave plate 29a is 150 degrees, and the arrangement angle of the opposite half-wave plate 29b is 30 degrees. Is set to

  The operation of the liquid crystal display device 54 when set as described above is shown in FIG. The reflective display area 5 operates as follows. In a state where no voltage is applied to the liquid crystal 13a, the linearly polarized light having an arrangement angle of 15 degrees transmitted through the polarizing plate 21b becomes linearly polarized light having an arrangement angle of 45 degrees when transmitted through the half-wave plate 29b, and transmitted through the liquid crystal 13a. It becomes clockwise circularly polarized light, is reflected by the reflecting plate 9, is counterclockwise circularly polarized light, is further transmitted through the liquid crystal 13 a, and becomes linearly polarized light having an arrangement angle of 135 degrees. Subsequently, when the light passes through the half-wave plate 29b, it becomes linearly polarized light having an arrangement angle of 105 degrees, and thus cannot pass through the polarizing plate 21b, resulting in black display. In a state where a voltage is applied to the liquid crystal 13a, the arrangement angle of the liquid crystal 13a is set to 45 degrees. In this state, the linearly polarized light whose arrangement angle is 45 degrees by sequentially transmitting through the polarizing plate 21b and the half-wave plate 29b does not change even when the liquid crystal 13a is transmitted. Even after being reflected and further transmitted through the liquid crystal 13a, the arrangement angle remains 45 degrees. Subsequently, when the light passes through the half-wave plate 29b, it returns to linearly polarized light with an arrangement angle of 15 degrees, so that it passes through the polarizing plate 21b and becomes white display. That is, the reflective display area 5 is normally black.

  The transmissive display area 6 operates as follows. In a state where no voltage is applied to the liquid crystal 13a, the linearly polarized light with the arrangement angle of 75 degrees transmitted through the polarizing plate 21a becomes the linearly polarized light with the arrangement angle of 45 degrees when transmitted through the half-wave plate 29a and is transmitted through the liquid crystal 13a. It becomes linearly polarized light with an arrangement angle of 135 degrees. Subsequently, when the light passes through the half-wave plate 29b, it returns to linearly polarized light having an arrangement angle of 105 degrees, so that it cannot pass through the polarizing plate 21b, resulting in black display. In a state where a voltage is applied to the liquid crystal 13a, the arrangement angle of the liquid crystal 13a is set to 45 degrees. In this state, the linearly polarized light whose arrangement angle is 45 degrees by sequentially transmitting through the polarizing plate 21a and the half-wave plate 29a does not change even when the liquid crystal 13a is transmitted, and remains at the arrangement angle of 45 degrees. It is. Subsequently, when the light passes through the half-wave plate 29b, it becomes linearly polarized light with an arrangement angle of 15 degrees, so that it passes through the polarizing plate 21b and becomes white display. That is, the transmission type display area 6 is normally black.

  As described above, by using the technique disclosed in Non-Patent Document 1 (S.I.D.2003 International Symposium, Digest of Technical Papers, p.592 to p.595), the transmission type is used. Both the display area and the reflective display area can be set to a normally black mode. Furthermore, when this technology is used, the transmittance and transmittance can be kept low over a wide wavelength range by matching the wavelength dependence of the refractive index anisotropy between the half-wave plate and the liquid crystal. Can be set.

  However, the transflective liquid crystal display device disclosed in Non-Patent Document 1 (S.I.D.2003 International Symposium, Digest of Technical Papers, p.592-p.595) still has the following: There remains a problem with display quality.

  FIG. 15 shows the p. Of SID 2003 International Symposium Digest of Technical Papers. 592-p. FIG. 59 is a diagram showing a result of simulation performed on viewing angle characteristics in the transmissive display region of the transflective liquid crystal display device disclosed in 595. In FIG. 15, in a polar coordinate system corresponding to a viewing angle of 0 to 80 degrees polar angle and 0 to 360 degrees azimuth, the contrast values are 500, 200, 100, 50, 20, 10, 5 in order from the inside. The corresponding isocontrast curve is shown. The reference axis of the viewing angle is indicated by a concentric dotted line for every 20 degrees of polar angle and by a radial dotted line for every 30 degrees of azimuth. The isocontrast curve corresponding to the contrast 10 in FIG. 15 is developed in the range of about 50 degrees in the vertical and horizontal directions, and in the range of less than 60 degrees in the oblique direction. As a transflective liquid crystal display device, it has a relatively good viewing angle characteristic, but it can be said that it is insufficient as compared with the degree of improvement of recent transmissive liquid crystal display devices.

  The present invention has been made in view of such a problem, and in a transflective liquid crystal display device having a reflective region and a transmissive region, good black display characteristics are obtained in both the reflective display region and the transmissive display region. An object of the present invention is to provide a transflective liquid crystal display device that is realized and has excellent viewing angle characteristics, and an electronic device including the transflective liquid crystal display device.

A transflective liquid crystal display device according to a reference example of the present invention includes a liquid crystal layer including a plurality of pixels, each of which includes a reflective display region and a transmissive display region driven by a lateral electric field, and sandwiches the liquid crystal layer. And two optical polarizers arranged in this manner, and an optical layer arranged so as to be interposed in the light path in the reflective display region and rotating the arrangement angle of linearly polarized light by 45 degrees.

  Thus, by providing an optical layer that rotates the arrangement angle of linearly polarized light by 45 degrees in the reflective display area, the arrangement angle of linearly polarized light in the reflective display area is rotated by 45 degrees. It can be converted into normally black display characteristics. As a result, both the transmissive display area and the reflective display area are in a normally black mode, and a transflective liquid crystal display device having a wide field of view characteristic is provided without any special contrivance in the device structure and signal processing configuration. . The optical layer may be a uniaxially aligned half-wave plate or a twisted-orientation optical rotator as long as linearly polarized light can be rotated by 45 degrees.

  In the case of using a uniaxially oriented half-wave plate, one (one layer) half-wave plate may be used, but by laminating at least two (two layers) or more in the reflective display region The transmittance during black display can be kept low over a wide wavelength range. That is, an achromatic black display can be obtained and a high contrast can be realized. When two or more half-wave plates are stacked and used in this way, the arrangement angle of each layer may be set so that the arrangement angle of linearly polarized light is finally rotated by 45 degrees. Can be set so that the transmittance can be kept low in a wide wavelength range by matching the wavelength dependence of the refractive index anisotropy of the liquid crystal layer and the half-wave plate.

Transflective liquid crystal display device according to the present invention, each of the plurality of pixels, the reflective display region to be plane switching, and, together with the liquid crystal layer made of a transmissive display region that is transverse electric field driving is provided, wherein The reflective display area is provided with a reflective layer that reflects the transmitted light that has passed through the liquid crystal layer. In the reflective display area, the product of the thickness dr of the liquid crystal layer and the refractive index anisotropy Δn (Δn × dr) is set to (λ / 4) (λ: wavelength of linearly polarized light, the same applies hereinafter), and the product (Δn) of the thickness df of the liquid crystal layer and the refractive index anisotropy Δn in the transmissive display region. Xdf) is set to (λ / 2), and two polarizing plates are arranged so as to sandwich the liquid crystal layer, and one side of two sides sandwiching the liquid crystal layer in the reflective display region together with the reflective layer is disposed on the other side of the arrangement direction of the linearly polarized light 2 The half-wave plate of the two rotating 45 degrees in combination, been arranged, the two polarizing plates, its transmission axis orthogonal to each other, and the transmission axis of one of the polarizing plates but wherein the is arranged to coincide with the alignment direction of the liquid crystal layer when no voltage is applied.
In the transflective liquid crystal display device according to the present invention, each of the plurality of pixels is provided with a liquid crystal layer including a reflective display region driven by a vertical electric field and a transmissive display region driven by a horizontal electric field. The reflective display region is provided with a reflective layer that reflects the transmitted light that has passed through the liquid crystal layer. In the reflective display region, the product of the thickness dr of the liquid crystal layer and the refractive index anisotropy Δn ( Δn × dr) is set to (λ / 4), and the product (Δn × df) of the thickness df of the liquid crystal layer and the refractive index anisotropy Δn is (λ / 2) in the transmissive display region. And two polarizing plates arranged so as to sandwich the liquid crystal layer, and in the reflective display area, the reflective layer is disposed on one side of two sides sandwiching the liquid crystal layer On the other side, the alignment angle of linearly polarized light is rotated 45 degrees by combining two The two half-wave plates are arranged, the two polarizing plates have their transmission axes orthogonal to each other, and a voltage is applied to the transmission axis of one of the polarizing plates. The liquid crystal layer is arranged so as to coincide with the orientation direction of the liquid crystal layer when it is not.
In the transflective liquid crystal display device according to the present invention, each of a plurality of pixels is provided with a liquid crystal layer including a reflective display region driven by a horizontal electric field and a transmissive display region driven by a horizontal electric field. The reflective display region is provided with a reflective layer that reflects the transmitted light that has passed through the liquid crystal layer. In the reflective display region, the product of the thickness dr of the liquid crystal layer and the refractive index anisotropy Δn ( Δn × dr) is set to (λ / 4), and the product (Δn × df) of the thickness df of the liquid crystal layer and the refractive index anisotropy Δn is (λ / 2) in the transmissive display region. Two polarizing plates arranged so as to sandwich the liquid crystal layer, and two on each of two sides sandwiching the liquid crystal layer and the reflective layer, the reflective display region and the transmissive display region, respectively. 45. The arrangement angle of the linearly polarized light is 45 for each of the two combinations. A total of four half-wave plates rotated each time, the two polarizing plates have their transmission axes orthogonal to each other, and the transmission axis of one of the polarizing plates has a voltage of The liquid crystal layer is arranged so as to coincide with the orientation direction when not applied.
Instead of the two half-wave plates, there may be two twisted orientation type optical rotation plates capable of rotating the arrangement angle of linearly polarized light by 45 degrees.
The combination of the arrangement angle of the wave plate of the two half-arranged so as to sandwich the liquid crystal layer, respectively, 175 ° and 152.5 °, it is set to 5 degrees and 27.5 degrees, or The combination of the arrangement angles of the two half-wave plates arranged in the reflective display area and rotating the arrangement angle of the linearly polarized light by 45 degrees is preferably set to 175 degrees and 152.5 degrees. .

  Thus, by providing an optical layer that rotates the arrangement angle of linearly polarized light by 45 degrees on both sides of the liquid crystal layer, the arrangement angle of linearly polarized light is rotated by 45 degrees in the reflective display region. Normally white can be converted to display characteristics of normally black. Thus, both the transmissive display area and the reflective display area are in the normally black mode, and a transflective liquid crystal display device having a wide field of view characteristic is provided without any special contrivance in the device structure or signal processing configuration. The optical layer mentioned here may be a uniaxially oriented half-wave plate or a twisted-orientation optical rotatory plate as long as linearly polarized light can be rotated by 45 degrees.

  In the present invention, since the optical layer is not formed selectively only in the reflective display area, but is disposed on the outer front surface of the opposing and lower substrates, it can be realized by a simple manufacturing process. .

  In the present invention, the two polarizing plates are arranged so that the transmission axes thereof are orthogonal to each other, and the orientation direction in a state where no voltage is applied to the liquid crystal layer coincides with the transmission axis of one of the polarizing plates. It is arranged so that it may be arranged.

    An electronic apparatus according to the present invention includes the transflective liquid crystal display device.

  According to the present invention, a transflective liquid crystal display device having good black display characteristics and excellent wide viewing angle characteristics in both the reflective display area and the transmissive display area is provided. This can contribute to the improvement of image characteristics of an electronic device equipped with a liquid crystal display device.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. First, a first embodiment of the present invention will be described. FIG. 1A is a diagram showing a transflective liquid crystal display device according to this embodiment. FIG. 1B is a diagram showing the arrangement angles of the polarizing plate, the liquid crystal layer, and the half-wave plate when viewed from the counter substrate side. Further, FIG. 1C is a diagram showing the operation of FIG.

  As shown in FIG. 1A, the transflective liquid crystal display device 150 includes a lower substrate 11, a counter substrate 12, a liquid crystal layer 13 sandwiched between both substrates, and a lower substrate 11. It is formed from the arranged backlight 40.

  The lower substrate 11 has a polarizing plate 21a disposed at the bottom, a transparent insulating substrate 22a disposed thereon, and an insulating film 8a disposed thereon.

  Further, the counter substrate 12 has a polarizing plate 21b disposed at the top and a transparent insulating substrate 22b disposed thereunder.

  Further, the liquid crystal layer 13 is divided into a plurality of pixels arranged in a matrix, and a reflective display region 5 and a transmissive display region 6 are provided in each pixel. In the liquid crystal layer 13 in the transmissive display area, the liquid crystal 13a and the common electrode 26 and the pixel electrode 27 for driving the liquid crystal 13a are disposed on the insulating film 8a. In the liquid crystal layer 13 in the reflective display region, an insulating film 8b is disposed on the insulating film 8a, and a reflective layer 9 is disposed on the insulating film 8b. An insulating film 8c is disposed on the reflective layer 9, and a liquid crystal 13a and a common electrode 26 and a pixel electrode 27 for driving the liquid crystal 13a are disposed on the insulating film 8c. Further, half-wave plates 29b and 29d are disposed on the liquid crystal 13a, that is, below the transparent insulating substrate 22b, as optical layers for rotating linearly polarized light by 45 degrees. A twist orientation type optical rotatory plate may be used instead of the half-wave plate.

  Although omitted in FIG. 1A for the sake of simplicity, a horizontal alignment film is formed on the surfaces of the lower substrate 11 and the opposite substrate 12 that sandwich the liquid crystal layer 13 in contact with the liquid crystal layer 13. The angle formed by the two horizontally opposed films is referred to as a twist angle, and the liquid crystal layer 13 is aligned so that the twist angle is uniaxial.

  In the reflective display area 5, the product (Δn × dr) of the thickness dr of the liquid crystal layer 13 and the refractive index anisotropy Δn is set to (λ / 4). In the transmissive display area 6, The product (Δn × df) of the thickness df and the refractive index anisotropy Δn is set to (λ / 2).

  As shown in FIG. 1B, in a state where no voltage is applied to the liquid crystal 13a, when the arrangement angle of the polarizing plate 21a on the lower side of the reflective display region 5 and the transmissive display region 6 is 0 degree, The arrangement angle of the polarizing plate 21b is set to 90 degrees, the arrangement angle of the liquid crystal 13a is set to 90 degrees, and the arrangement angles of the half-wave plates 29b and 29d are set to 175 degrees and 152.5 degrees, respectively.

  The operation of the transflective liquid crystal display device 150 when it is set as described above is shown in FIG. The reflective display area 5 operates as follows. In a state where no voltage is applied to the liquid crystal 13a, linearly polarized light having an arrangement angle of 90 degrees transmitted through the polarizing plate 21b becomes linearly polarized light having an arrangement angle of 45 degrees when sequentially transmitted through the half-wave plates 29b and 29d. It passes through the liquid crystal 13a and becomes clockwise circularly polarized light. Then, it is reflected by the reflecting plate 9 to become counterclockwise circularly polarized light, and further passes through the liquid crystal 13a to become linearly polarized light having an arrangement angle of 135 degrees. Subsequently, when the light is sequentially transmitted through the half-wave plates 29d and 29b, it becomes linearly polarized light having an arrangement angle of 0 degrees, and thus cannot be transmitted through the polarizing plate 21b, resulting in black display.

  Next, in a state where a voltage is applied to the liquid crystal 13a, the arrangement angle of the liquid crystal 13a is set to 45 degrees. In this state, the linearly polarized light whose arrangement angle is 45 degrees by sequentially transmitting through the polarizing plate 21b and the half-wave plates 29b and 29d does not change even when the liquid crystal 13a is transmitted. The arrangement angle remains 45 degrees even after being reflected by the reflecting plate 9 and further transmitted through the liquid crystal 13a. Further, when the light is sequentially transmitted through the half-wave plates 29d and 29b, the light returns to linearly polarized light having an arrangement angle of 90 degrees, and thus the light is transmitted through the polarizing plate 21b to display white. That is, the reflective display area 5 is normally black.

  The transmissive display area 6 operates as follows. In a state where no voltage is applied to the liquid crystal 13a, the linearly polarized light (arrangement angle 0 degree) transmitted through the polarizing plate 21a remains at an arrangement angle of 0 degrees even when transmitted through the liquid crystal 13a, and the polarizing plate has an arrangement angle of 90 degrees. 21b cannot be transmitted and a black display is obtained. When the voltage is applied to the liquid crystal 13a, the arrangement angle of the liquid crystal 13a changes to 45 degrees. Then, the linearly polarized light (arrangement angle 0 degree) transmitted through the polarizing plate 21a is transmitted through the liquid crystal 13a to become linearly polarized light with an arrangement angle of 90 degrees, and is transmitted through the polarizing plate 21b with an arrangement angle of 90 degrees to display white. . That is, it becomes normally black. In particular, black display in the transmissive display area 6 is realized by an optical arrangement in which a liquid crystal layer is arranged between two orthogonal polarizing plates, and the arrangement angle of the liquid crystal layer coincides with the arrangement angle of one polarizing plate. ing. That is, the birefringence effect is not used when performing black display. For this reason, even if the thickness of the liquid crystal layer fluctuates due to the influence of the manufacturing process, the quality of black display is not directly affected, and a good contrast can be obtained.

  In contrast, in the transmissive display region of the transflective liquid crystal display device shown in FIG. 11 which is the prior art, an exquisite balance between the birefringence effect by the liquid crystal layer and the birefringence effect by the half-wave plate. Therefore, if any birefringence effect deviates from the design value (for example, if the layer thickness of the liquid crystal layer fluctuates), the quality of the black display is likely to deteriorate.

  In the first embodiment, a normally black transflective liquid crystal display device with a wide viewing angle can be realized by driving the reflective display area 5 and the transmissive display area 6 with a horizontal electric field.

  Further, the electronic apparatus according to the present embodiment is a mobile phone equipped with a transflective liquid crystal display device constituted by the reflective display area 5 and the transmissive display area 6.

  Hereinafter, a supplementary explanation will be given for the arrangement angles of the half-wave plates 29b and 29d. In general, the half-wave plate has an effect of changing the arrangement angle of incident linearly polarized light. Specifically, if the angle between the arrangement angle of the half-wave plate and the arrangement angle of the linearly polarized light incident thereon is φ, the linearly polarized light has an arrangement angle after passing through the half-wave plate. 2φ changes. Based on this action, in the operation of the transflective liquid crystal display device 150 described above, linearly polarized light having an arrangement angle of 90 degrees transmitted through the polarizing plate 21b is first transmitted through the half-wave plate 29b disposed at 175 degrees. By doing so, linearly polarized light with an arrangement angle of 260 degrees is obtained. Furthermore, by transmitting through the half-wave plate 29d arranged at 152.5 degrees, linearly polarized light having an arrangement angle of 45 degrees is obtained.

  In the present embodiment, an example using two (two layers) half-wave plates has been shown, but instead, for example, one half-wave plate is arranged so that the arrangement angle is 67.5 degrees. By installing, the arrangement angle of the incident linearly polarized light can be rotated by 45 degrees. However, the present inventors have confirmed through experiments that the liquid crystal layer and the half-wave plate are obtained by using two half-wave plates as shown in the present embodiment and setting the above-mentioned arrangement angle. It has been found that the wavelength dependence of the refractive index anisotropy is matched with the above, and the transmittance at the time of black display can be kept low in a wide wavelength range, so that an achromatic black display can be obtained. This effect will be described with reference to FIG. 2 and FIG.

  FIG. 2 shows the reflection spectrum at the time of black display and white display when two half-wave plates are used as shown in the present embodiment and the arrangement angle is set as above, and the horizontal axis indicates the wavelength, It is a figure which shows the transmittance | permeability on the axis | shaft. As shown by the white display line 31, when the wavelength changes from 400 nm to about 470 nm, the transmittance increases from about 0.07 to 0.3, and when the wavelength increases beyond about 470 nm, the transmittance decreases slightly at around 600 nm. However, it increases almost slowly, and the transmittance when the wavelength is 700 nm is about 0.35. As shown by the black display line 32, the transmittance increases from about 0.02 to about 0.04 when the wavelength is from 400 nm to about 410 nm, but immediately starts to decrease, and when the wavelength increases beyond about 450 nm, the transmittance is zero. It is. FIG. 3 shows a black display in which a wavelength is plotted on the horizontal axis and the transmittance is plotted on the vertical axis when one half-wave plate is installed with an arrangement angle of 67.5 degrees. It is a figure which shows the reflection spectrum at the time of white display. As shown by the white display line 31, when the wavelength changes from 400 nm to about 480 nm, the transmittance increases from about 0.02 to 0.3, and when the wavelength increases beyond about 480 nm, the transmittance increases at around 600 nm. Although it decreases slightly, it is generally constant. As shown by the black display line 32, when the wavelength changes from 400 nm to about 430 nm, the transmittance increases from about 0.08 to about 0.25, but immediately begins to decrease, and at about 550 nm, the transmittance becomes zero. The transmittance increases when the wavelength exceeds about 550 nm, and the transmittance when the wavelength is 700 nm is about 0.23. As shown in the present embodiment, by using two half-wave plates and setting the above-mentioned arrangement angle, it is possible to keep the transmittance during black display low in a wide wavelength range, and therefore achromatic black display Can be obtained.

  In the transflective liquid crystal display device according to the second embodiment of the present invention, the reflective display region is a vertical electric field driving method, and the transmissive display region is a horizontal electric field driving method. FIG. 4A is a cross-sectional view showing the transflective liquid crystal display device according to this embodiment. FIG. 4B is a diagram showing the arrangement angles of the polarizing plate, the liquid crystal layer, and the half-wave plate when viewed from the counter substrate side. Further, FIG. 4C is a diagram showing the operation of FIG.

  The difference between the optical arrangement of the reflective display area 5 shown in FIG. 4A and the optical arrangement of the reflective display area 5 shown in FIG. 1A is arranged in the reflective area of the transflective display device shown in FIG. The reflecting plate 9 and the lateral electric field drive electrode 7 are not arranged in the reflective region of the transflective display device shown in FIG. 4, but instead, in the reflective region of the transflective display device shown in FIG. A transparent reflective pixel electrode 10 is formed on the second insulating film 8b, and a transparent counter electrode 14 is formed below the half-wave plates 29b and 29d disposed below the counter substrate 12. It is a point. Thereby, in the reflective display area 5 shown in FIG. 4A, a vertical electric field is formed between the reflective pixel electrode 10 and the counter electrode 14. The optical arrangement of the transmissive display area 6 in FIG. 4A is the optical arrangement of the transmissive display area 6 in FIG. 1A, the polarizing plate when viewed from the counter substrate 12 in FIG. The arrangement angle of the liquid crystal layer is the same as that shown in FIGS. Further, instead of the half-wave plate, a twist orientation type optical rotator may be used.

  The operation of the transflective liquid crystal display device 151 when set as described above is shown in FIG. The reflective display area 5 operates as follows. In a state where no voltage is applied to the liquid crystal 13a, the linearly polarized light having an arrangement angle of 90 degrees transmitted through the polarizing plate 21b becomes linearly polarized light having an arrangement angle of 45 degrees when sequentially transmitted through the half-wave plates 29b and 29d, and the liquid crystal 13a is transmitted through the liquid crystal 13a. The light passes through and becomes clockwise circularly polarized light, is reflected by the reflective pixel electrode 10, passes counterclockwise circularly polarized light, further passes through the liquid crystal 13 a, and becomes linearly polarized light having an arrangement angle of 135 degrees. Subsequently, when the light is sequentially transmitted through the half-wave plates 29d and 29b, it becomes linearly polarized light having an arrangement angle of 0 degrees, and thus cannot be transmitted through the polarizing plate 21b, resulting in black display. In a state where a voltage is applied between the reflective pixel electrode 10 and the counter electrode 14, the liquid crystal molecules of the liquid crystal 13a rise in the vertical direction. In this state, the linearly polarized light whose arrangement angle is 45 degrees by sequentially transmitting through the polarizing plate 21b and the half-wave plates 29b and 29d does not change the arrangement angle even when transmitted through the liquid crystal 13a. Even after being reflected by the electrode 10 and further transmitted through the liquid crystal layer 13, the arrangement angle remains 45 degrees. Subsequently, when the light passes through the half-wave plates 29d and 29b sequentially, the light returns to linearly polarized light having an arrangement angle of 90 degrees, so that it passes through the polarizing plate 21b and becomes white display. That is, the reflective display area 5 is normally black. The operation in the transmissive display area 6 is the same as that in FIG.

  As shown in this embodiment, by using two half-wave plates and setting the above-mentioned arrangement angle, the reflective display region 5 is normally in both the reflective display region and the transmissive display region even in the vertical electric field. Black can be realized.

  Further, the electronic apparatus according to the present embodiment is a mobile phone equipped with a transflective liquid crystal display device constituted by the reflective display area 5 and the transmissive display area 6.

  Next, a third embodiment of the present invention will be described. FIG. 5A is a cross-sectional view showing the transflective liquid crystal display device according to this embodiment. FIG. 5B is a diagram illustrating the arrangement angles of the polarizing plate, the half-wave plate, and the liquid crystal layer when viewed from the counter substrate 12. As shown in FIGS. 5A to 5C, in the transflective liquid crystal display device 152 according to the present embodiment, the optical layer that rotates the linearly polarized light by 45 degrees includes the transparent insulating substrate 22b of the counter substrate 12 and the transparent insulating substrate 22b. It is arranged between the polarizing plate 21b and between the transparent insulating substrate 22a of the lower substrate 11 and the polarizing plate 21a. As the optical layer, two half-wave plates are laminated. Although the half-wave plate used in this embodiment is a uniaxially stretched film made of polycarbonate, various materials such as a norbornene-based uniaxially stretched film can be used. Further, instead of the half-wave plate, a twist orientation type optical rotator may be used.

  As shown in FIG. 5A, the difference between the transflective liquid crystal display device 152 of the third embodiment and the transflective liquid crystal display device 150 of the first embodiment described above is that the transflective liquid crystal display. The half-wave plates 29b and 29d arranged under the transparent insulating substrate 22b of the device 150 are removed, and the half-wave plates 29b and 29d are disposed between the polarizing plate 21b and the transparent insulating substrate 22b. Both the reflective region and the transmissive region, that is, the entire display region, and the half-wave plates 29a and 29c are disposed between the polarizing plate 21a and the transparent insulating substrate 22a. It is arranged in the entire display area. Since the configuration other than this is the same as the cross-sectional structure of FIG. As shown in FIG. 5B, the arrangement angles of the polarizing plates 21a and 21b and the liquid crystal layer 13 are the same as those in FIG. The arrangement angles of the half-wave plates 29b and 29d are the same as those in FIG. The arrangement angles of the half-wave plates 29a and 29c are set to 5 degrees and 27.5 degrees, respectively.

  FIG. 5C shows the operation of the transflective liquid crystal display device 152 when it is set as described above. In the reflective display region 5, although the arrangement positions of the half-wave plates 29b and 29d are different from the transflective liquid crystal display device shown in FIG. 1A, the arrangement angle is the same as the arrangement angle shown in FIG. Since they are similar, the operation is the same as the operation shown in FIG. Therefore, it becomes normally black.

  The transmissive display area 6 operates as follows. In a state where no voltage is applied to the liquid crystal 13a, the linearly polarized light having an arrangement angle of 0 ° transmitted through the polarizing plate 21a becomes linearly polarized light having an arrangement angle of 45 ° when sequentially transmitted through the half-wave plates 29a and 29b, and the liquid crystal 13a is transmitted through the liquid crystal 13a. The light is transmitted and becomes linearly polarized light having an arrangement angle of 135 degrees. Subsequently, when the light passes through the half-wave plates 29d and 29b in sequence, it returns to linearly polarized light with an arrangement angle of 0 degrees, so that it cannot pass through the polarizing plate 21b, resulting in black display. In a state where a voltage is applied to the liquid crystal 13a, the arrangement angle of the liquid crystal 13a is set to 45 degrees. In this state, the linearly polarized light whose arrangement angle is 45 degrees by sequentially transmitting through the polarizing plate 21a and the half-wave plates 29a and 29c does not change even when the liquid crystal 13a is transmitted, and the arrangement angle is 45 degrees. Remains. Subsequently, when the light is sequentially transmitted through the half-wave plates 29d and 29b, it becomes linearly polarized light with an arrangement angle of 90 degrees, so that it is transmitted through the polarizing plate 21b and white display is obtained. That is, the transmissive display area 6 is normally black.

  In the following, the explanation of the arrangement angle of the half-wave plates 29a and 29c will be supplemented. Based on the action of the general half-wave plate described in the description of the first embodiment, in the operation of the transflective liquid crystal display device 152 of this embodiment, the arrangement angle 0 transmitted through the polarizing plate 21a is 0. First, the linearly polarized light of the degree is transmitted through the half-wave plate 29a arranged at 5 degrees to become linearly polarized light having an arrangement angle of 10 degrees. Further, by transmitting through the half-wave plate 29c arranged at 27.5 degrees, linearly polarized light having an arrangement angle of 45 degrees is obtained. In the present embodiment, the half-wave plates 29a and 29c and the half-wave plates 29b and 29d are arranged at symmetrical arrangement angles with the liquid crystal layer 13 being sandwiched therebetween, thereby canceling the effects of each other. Thus, high contrast in the transmissive display area 6 is realized.

  As described above, in the configuration shown in this embodiment, a normally black transflective liquid crystal display device with a wide viewing angle can be realized by driving the reflective display region 5 and the transmissive display region 6 with a lateral electric field. In the present embodiment, the optical layer that rotates the linearly polarized light by 45 degrees is arranged on the entire surfaces of the opposing and lower substrates without being selectively formed only in the reflective display area 5, so that simple manufacturing is possible. It can be realized by a process.

  FIG. 6 is a diagram illustrating a result of simulation of the viewing angle characteristics in the transmissive display region of the transflective liquid crystal display device 152. In FIG. 6, as in FIG. 15, in the polar coordinate system corresponding to the viewing angle of 0 to 80 degrees polar angle and 0 to 360 degrees azimuth, the contrast values are 500, 200, 100, 50, 20 in order from the inside. Isocontrast curves corresponding to 10, 5 are shown. The reference axis of the viewing angle is indicated by a concentric dotted line for every 20 degrees of polar angle and by a radial dotted line for every 30 degrees of azimuth. The isocontrast curve corresponding to the contrast 10 in FIG. 6 is developed in the range of about 50 degrees in the vertical and horizontal directions, and in the oblique direction in the range of 80 degrees or more. Compared with FIG. It can be seen that is obtained.

  Further, the electronic apparatus according to the present embodiment is a mobile phone equipped with a transflective liquid crystal display device constituted by the reflective display area 5 and the transmissive display area 6.

(A) thru | or (c) is a figure which shows the transflective liquid crystal display device of 1st Embodiment, (a) shows optical arrangement | positioning, (b) shows the arrangement | positioning angle of each component, (c ) Indicates the operation. It is a figure which shows the transmission spectrum at the time of the black display of the reflective type display area of the transflective liquid crystal display device of 1st Embodiment, and a white display. It is a figure which shows the reflection spectrum at the time of the black display of the reflection type display area of the transflective liquid crystal display device by another structural example of 1st Embodiment, and a white display. (A) thru | or (c) is a figure which shows the transflective liquid crystal display device of 2nd Embodiment, (a) shows optical arrangement | positioning, (b) shows the arrangement | positioning angle of each component, (c ) Indicates the operation. (A) thru | or (c) is a figure which shows the transflective liquid crystal display device of 3rd Embodiment, (a) shows optical arrangement | positioning, (b) shows the arrangement | positioning angle of each component, (c ) Indicates the operation. It is a figure which shows the viewing angle characteristic of the transflective liquid crystal display device of 3rd Embodiment. It is sectional drawing of the conventional transflective liquid crystal display device. (A) thru | or (c) is a figure which shows the transflective liquid crystal display device of the 1st prior art, (a) shows optical arrangement | positioning, (b) shows the arrangement angle of each component, (c ) Indicates the operation. (A) thru | or (c) is a figure which shows the transflective liquid crystal display device of the 2nd prior art, (a) shows optical arrangement | positioning, (b) shows the arrangement | positioning angle of each component, (c ) Indicates the operation. (A) thru | or (c) is a figure which shows the transflective liquid crystal display device of the 3rd prior art, (a) shows optical arrangement | positioning, (b) shows the arrangement | positioning angle of each component, (c ) Indicates the operation. (A) thru | or (c) is a figure which shows the transflective liquid crystal display device of a 4th prior art, (a) shows optical arrangement | positioning, (b) shows the arrangement angle of each component, (c ) Indicates the operation. It is a figure which shows the transmission spectrum at the time of the black display of the transmissive | pervious display area of the transflective liquid crystal display device of a 4th prior art, and a white display. It is a figure which shows the reflection spectrum at the time of the black display of the reflection type display area of the transflective liquid crystal display device of a 4th prior art, and a white display. (A) thru | or (c) is a figure which shows the transflective liquid crystal display device of a 5th prior art, (a) shows optical arrangement | positioning, (b) shows the arrangement | positioning angle of each component, (c ) Indicates the operation. It is a figure which shows the viewing angle characteristic of the transflective liquid crystal display device of a 5th prior art.

Explanation of symbols

5; reflective display region 6; transmissive display region 7; lateral electric field drive electrode 8; insulating film 8a; first insulating film 8b; second insulating film 8c; Pixel electrode 11; lower substrate 12; counter substrate 13; liquid crystal layer 13a; liquid crystal 14; counter electrode (ITO)
21a; Polarizing plate (lower side)
21b: Polarizing plate (opposite side)
22a: Transparent insulating substrate (lower side)
22b; transparent insulating substrate (opposite side)
26; common electrode 27; pixel electrodes 29a, 29b, 29c, 29d; half-wave plate 31; white display line 32; black display line 40;

Claims (6)

Each of the plurality of pixels is provided with a liquid crystal layer including a reflective display region driven by a horizontal electric field and a transmissive display region driven by a horizontal electric field , and the reflective display region transmits the liquid crystal layer. A reflective layer for reflecting the transmitted light is provided,
In the reflective display region, the product (Δn × dr) of the thickness dr of the liquid crystal layer and the refractive index anisotropy Δn is set to (λ / 4) (λ: wavelength of linearly polarized light, the same applies hereinafter). In the transmissive display region, the product (Δn × df) of the thickness df of the liquid crystal layer and the refractive index anisotropy Δn is set to (λ / 2),
Comprises two polarizing plates disposed so as to sandwich the liquid crystal layer,
In the reflective display region, the with one said reflective layer on the side of the two sides that sandwich the liquid crystal layer is disposed, on the other side, the rotating 45 degrees the arrangement direction of the linearly polarized light in two combinations Two half-wave plates are arranged ,
As the two polarizing plates, its transmission axis orthogonal to each other, and the transmission axis of one of the polarizing plates matches with the alignment direction of the liquid crystal layer when no voltage is applied A transflective liquid crystal display device characterized by being arranged. Each of the plurality of pixels is provided with a liquid crystal layer including a reflective display region driven by a vertical electric field and a transmissive display region driven by a horizontal electric field, and the reflective display region transmits the liquid crystal layer. A reflective layer for reflecting the transmitted light is provided,
In the reflective display region, the product (Δn × dr) of the thickness dr of the liquid crystal layer and the refractive index anisotropy Δn is set to (λ / 4), and in the transmissive display region, the liquid crystal layer The product (Δn × df) of the thickness df and the refractive index anisotropy Δn is set to (λ / 2),
Comprising two polarizing plates arranged so as to sandwich the liquid crystal layer,
In the reflective display region, the reflective layer is disposed on one side of the two sides sandwiching the liquid crystal layer, and on the other side, the arrangement angle of the linearly polarized light is rotated by 45 degrees in a combination of two sheets. Two half-wave plates are arranged,
The two polarizing plates have their transmission axes orthogonal to each other, and the transmission axis of one of the polarizing plates coincides with the alignment direction of the liquid crystal layer when no voltage is applied. A transflective liquid crystal display device characterized by being arranged. Each of the plurality of pixels is provided with a liquid crystal layer including a reflective display region driven by a horizontal electric field and a transmissive display region driven by a horizontal electric field, and the reflective display region transmits the liquid crystal layer. A reflective layer for reflecting the transmitted light is provided,
In the reflective display region, the product (Δn × dr) of the thickness dr of the liquid crystal layer and the refractive index anisotropy Δn is set to (λ / 4), and in the transmissive display region, the liquid crystal layer The product (Δn × df) of the thickness df and the refractive index anisotropy Δn is set to (λ / 2),
Two polarizing plates arranged so as to sandwich the liquid crystal layer;
Two on each of the two sides sandwiching the liquid crystal layer and the reflective layer are arranged over the reflective display area and the transmissive display area, and the arrangement angle of linearly polarized light is rotated by 45 for each combination of the two sheets. A total of four half-wave plates,
The two polarizing plates have their transmission axes orthogonal to each other, and the transmission axis of one of the polarizing plates coincides with the alignment direction of the liquid crystal layer when no voltage is applied. A transflective liquid crystal display device characterized by being arranged. 4. Instead of the two half-wave plates, two twist-orientation type optical rotation plates capable of rotating the arrangement angle of linearly polarized light by 45 degrees are provided. A transflective liquid crystal display device described in 1. The combination of the arrangement angle of the wave plate of the two half-arranged so as to sandwich the liquid crystal layer, respectively, 175 ° and 152.5 °, it is set to 5 degrees and 27.5 degrees, or The combination of the arrangement angles of the two half-wave plates arranged in the reflective display area and rotating the arrangement angle of the linearly polarized light by 45 degrees is set to 175 degrees and 152.5 degrees. The transflective liquid crystal display device according to any one of claims 1 to 4 . Electronic apparatus, characterized in that the transflective liquid crystal display device according to any one of claims 1 to 4 is mounted.

Images