JP5103806B2 - Liquid crystal display element - Google Patents

Description

  The present invention relates to a liquid crystal display element that displays an image by controlling the orientation direction of liquid crystal molecules in a plane substantially parallel to a substrate surface.

  As a liquid crystal display element, a liquid crystal molecule is aligned substantially in parallel with the substrate surface with its molecular long axis aligned in one predetermined direction in a gap between a pair of substrates opposed to each other with a predetermined gap. The aligned liquid crystal layer is sealed, and arranged on either one of the mutually facing inner surfaces of the pair of substrates so as to be insulated from each other, thereby generating a lateral electric field substantially parallel to the substrate surface. Provided are a plurality of signal electrodes and a plurality of common electrodes for arranging a plurality of pixels in which the orientation direction of the liquid crystal molecules is controlled by an electric field in a matrix, and a polarizing plate is disposed on each of the outer surfaces of the pair of substrates. (See Patent Document 1).

The liquid crystal display element generates a lateral electric field corresponding to display data between a plurality of signal electrodes and a common electrode provided on the inner surface of one substrate, thereby changing the orientation direction of the liquid crystal molecules to the substrate surface. And display an image in a plane substantially parallel to the.
JP 2002-82357 A

  The above-described liquid crystal display element is a transmissive display element that displays an image by light incident from the side opposite to the observation side and transmitted through the liquid crystal layer, and displays an image by external light incident from the observation side. I could not.

  The present invention displays an image by controlling the orientation direction of liquid crystal molecules in a plane substantially parallel to the substrate surface, reflects light incident from the observation side, and emits the light to the observation side. Reflective display for displaying an image by controlling the image and transmissive display for displaying an image by controlling the emission of light incident from the opposite side to the observation side to display the image without reversing light and dark An object of the present invention is to provide a liquid crystal display element capable of achieving the above.

The liquid crystal display element of the present invention is
A pair of substrates on the opposite side and the observation side disposed opposite each other with a predetermined gap;
A liquid crystal layer encapsulated in a gap between the pair of substrates, wherein the liquid crystal molecules are aligned substantially parallel to the substrate surface with their molecular long axes aligned in one predetermined direction;
Insulated on either one of the opposing inner surfaces of the pair of substrates, generates a lateral electric field substantially parallel to the substrate surface, and the orientation of the liquid crystal molecules is controlled by the lateral electric field A plurality of signal electrodes and a plurality of common electrodes for forming a plurality of pixels arranged in a matrix,
A reflective display unit provided on an inner surface or an outer surface of the substrate on the opposite side so as to correspond to a predetermined region in each of the plurality of pixels, which reflects light incident from the observation side and emits the light to the observation side; A reflective film for forming a transmissive display unit other than the reflective display unit that transmits light incident from the opposite side to the observation side and emits the light to the observation side; and
The inner surface of at least one of the pair of substrates is provided so as to correspond to the reflective display portion of the plurality of pixels, and the refractive index anisotropy Δn of the liquid crystal and the liquid crystal layer thickness d of the reflective display portion, Is reduced by a value corresponding to a quarter wavelength of transmitted light as compared to the product Δnd of the refractive index anisotropy Δn of the liquid crystal and the liquid crystal layer thickness d of the transmissive display unit. A liquid crystal layer thickness adjusting layer for adjusting the liquid crystal layer thickness of the display unit;
A pair of polarizing plates on the outer side of the pair of substrates, on the observation side and on the opposite side, each arranged substantially parallel to the respective absorption axes ;
A retardation plate having a slow axis substantially parallel to the absorption axis of the opposite polarizing plate between the substrate opposite to the observation side and the opposite polarizing plate disposed on the outer surface thereof;
It is characterized by providing.

  In that case, it is preferable that the pair of polarizing plates be arranged so that their respective absorption axes are substantially shifted by 45 ° with respect to the direction of the molecular long axis of the liquid crystal molecules when there is no electric field.

  The liquid crystal display element of the present invention is disposed on either one of the opposing inner surfaces of a pair of substrates so as to be insulated from each other, and generates a lateral electric field substantially parallel to the substrate surface. By generating a lateral electric field corresponding to display data between a plurality of signal electrodes and a plurality of common electrodes for forming and arranging a plurality of pixels in which the orientation direction of liquid crystal molecules is controlled in a matrix, An image is displayed by controlling the orientation direction of the liquid crystal molecules of the plurality of pixels.

  Then, the liquid crystal display element reflects the light incident from the observation side to correspond to the predetermined regions in the plurality of pixels on the inner surface or the outer surface of the substrate opposite to the observation side, respectively. A reflective display unit that emits light to the observation side and a transmissive display unit that transmits light incident from the side opposite to the observation side and emits the light to the observation side are formed for each of the plurality of pixels. In order to reflect the incident light from the observation side and control the emission of the light to the observation side to display the image, and the incident light from the opposite side to the observation side It is possible to perform transmission display in which an image is displayed by controlling the emission of light to the observation side.

  In addition, the liquid crystal display element has a refractive index anisotropy Δn of the liquid crystal of the reflective display unit on the inner surface of at least one of the pair of substrates, corresponding to the reflective display unit of the plurality of pixels, respectively. The product Δnd of the liquid crystal layer thickness d is smaller than the product Δnd of the refractive index anisotropy Δn of the liquid crystal and the liquid crystal layer thickness d of the transmissive display unit by a value corresponding to a quarter wavelength of the transmitted light. As described above, since the liquid crystal layer thickness adjusting layer for adjusting the liquid crystal layer thickness of the reflective display portion is provided, the reflective display and the transmissive display can be performed without reversing the brightness.

  In the liquid crystal display element according to the present invention, it is desirable that the pair of polarizing plates be arranged with their absorption axes substantially parallel to each other. By doing so, both the reflective display portion and the transmissive display portion are arranged. The display can be a dark field-free display in which the luminance is minimized when the lateral electric field is not generated.

  In that case, it is preferable that the pair of polarizing plates are arranged so that their respective absorption axes are substantially shifted by 45 ° with respect to the direction of the molecular long axis of the liquid crystal molecules when no electric field is applied. The brightness and contrast of both the reflective display and the transmissive display can be increased.

  Further, when the pair of polarizing plates are arranged with their respective absorption axes substantially parallel, between the substrate on the opposite side to the observation side and the opposite side polarizing plate arranged on the outer surface thereof, It is preferable that the retardation plate for compensating the viewing angle dependency is arranged so that its slow axis is substantially parallel to or substantially perpendicular to the absorption axis of the opposite polarizing plate. By doing so, the field of view of the transmissive display can be widened.

  In the liquid crystal display element of the present invention, the pair of polarizing plates are arranged with their absorption axes substantially orthogonal to each other, a substrate on the side opposite to the observation side, and an opposite side polarizing plate arranged on the outer surface thereof. In the meantime, a λ / 2 retardation plate that gives a half-wave phase difference to the transmitted light is arranged with its slow axis substantially shifted by 45 ° with respect to the absorption axis of the opposite polarizing plate. In this way, the display of both the reflective display unit and the transmissive display unit can be made dark-free display and the field of view of the transmissive display can be widened.

  In that case, the pair of polarizing plates are arranged so that their absorption axes are substantially shifted by 45 ° in directions opposite to each other with respect to the direction of the molecular long axis of the liquid crystal molecules when no electric field is applied. The plate is preferably arranged so that the slow axis thereof is substantially parallel to the direction of the molecular long axis of the liquid crystal molecules when no electric field is applied. In this way, both the reflection display and the transmission display are performed. Brightness and contrast can be increased.

  Furthermore, in the liquid crystal display element of the present invention, the pair of polarizing plates are arranged with their absorption axes substantially orthogonal to each other, and between the observation side substrate and the observation side polarizing plate arranged on the outer surface thereof. In addition, it is desirable to arrange a λ / 2 retardation plate that gives a half-wave phase difference to transmitted light, with its slow axis substantially shifted from the absorption axis of the observation side polarizing plate by 45 °. By doing in this way, the display of both the said reflective display part and a transmissive display part can be made into a non-electric field dark display, and the visual field of the said transmissive display can be expanded.

  In that case, the pair of polarizing plates are arranged so that their absorption axes are substantially shifted by 45 ° in directions opposite to each other with respect to the direction of the molecular long axis of the liquid crystal molecules when no electric field is applied. The plate is preferably disposed so that its slow axis is substantially perpendicular to the direction of the molecular long axis of the liquid crystal molecules when no electric field is applied. In this way, the reflective display and the transmissive display are arranged. Both brightness and contrast can be increased.

(First embodiment)
1 to 6 show a first embodiment of the present invention. FIG. 1 is a plan view of a part of one substrate of a liquid crystal display element, and FIG. 2 is a line II-II in FIG. 1 of the liquid crystal display element. 3 is a cross-sectional view of the liquid crystal display element taken along line III-III in FIG. 1, FIG. 4 is a cross-sectional view of the liquid crystal display element taken along line IV-IV in FIG. 1, and FIG. FIG. 6 is a view of the orientation processing direction of the pair of substrates of the display element, the direction of the absorption axis of the pair of polarizing plates, and the direction of the slow axis of the viewing angle dependence compensation phase difference plate, viewed from the observation side. It is the figure which looked at the direction of the molecular long axis of the liquid crystal molecule at the time of no electric field and horizontal electric field generation in one pixel from the observation side.

  As shown in FIGS. 1 to 4, the liquid crystal display element includes an observation side (upper side in FIGS. 2 to 4) and a pair of transparent substrates 1 and 2 on the opposite side, facing each other with a predetermined gap. A liquid crystal layer enclosed in a gap between the pair of substrates 1 and 2 and having liquid crystal molecules 3a aligned substantially parallel to the surfaces of the substrates 1 and 2 with their molecular long axes aligned in one predetermined direction. 3 and the inner surface of one of the opposing inner surfaces of the pair of substrates 1 and 2, for example, the inner surface of the substrate 2 on the opposite side to the observation side, are arranged insulated from each other, A horizontal electric field substantially parallel to the surface is generated, and the plurality of pixels 100 in which the orientation direction of the liquid crystal molecules 3a is controlled by the horizontal electric field are arranged in the row direction (left and right direction of the screen) and the column direction (up and down direction of the screen). A plurality of signal electrodes 4 and a plurality of signal electrodes 4 are arranged in a matrix. It includes a common electrode 5, and a pair of polarizing plates 21 and 22 the outer surface of each arranged observation side and the opposite side of the pair of substrates 1 and 2.

  Hereinafter, the substrate 1 on the observation side is the front substrate, the substrate 2 opposite to the observation side is the rear substrate, the polarizing plate 21 on the observation side arranged on the outer surface of the front substrate 1 is the front polarizing plate, and the rear substrate 2. The polarizing plate 22 on the opposite side disposed on the outer surface is referred to as a rear polarizing plate.

  The pair of substrates 1 and 2 are joined via a frame-shaped sealing material (not shown), and the liquid crystal layer 3 is in a region surrounded by the sealing material in the gap between the pair of substrates 1 and 2. It is enclosed.

  This liquid crystal display element is an active matrix liquid crystal display element, and is formed between the signal electrode 4 and the common electrode 5 on the inner surface of the substrate 2 after the plurality of signal electrodes 4 and the common electrode 5 are provided. An active element 6 is provided for each of a plurality of pixels 100 arranged in a matrix composed of a region in which the orientation direction of the liquid crystal molecules 3a is controlled by the lateral electric field.

  The active element 6 includes a signal input electrode 10 and an output electrode 11, and a control electrode 7 that controls conduction between the input electrode 10 and the output electrode 11. The control electrode 7 is provided for each row. Are connected to the scanning line 12, the input electrode 10 is connected to the signal line 13 for each column, and the output electrode 11 is connected to the signal electrode 4.

  The active element 6 is a TFT (thin film transistor), and is formed on a substantially entire surface of the rear substrate 2 covering the gate electrode 7 and a gate electrode (control electrode) 7 formed on the substrate surface of the rear substrate 2. A transparent gate insulating film 8, an i-type semiconductor film 9 formed on the gate insulating film 8 so as to face the gate electrode 7, and an n-type semiconductor on both sides of the i-type semiconductor film 9. It consists of a drain electrode (input electrode) 10 and a source electrode (output electrode) 11 provided via a film (not shown).

  The scanning line 12 is provided between the pixel rows (lower side in FIG. 1) for each pixel row including a plurality of pixels 100 arranged in the row direction on the substrate surface of the rear substrate 2. The signal lines 13 are formed in parallel to the pixel rows and connected to the gate electrodes 7 of the TFTs 6 in each row, and the signal lines 13 are each composed of a plurality of pixels 100 arranged in the column direction on the gate insulating film 8. Each pixel column is formed between the pixel columns (on the left side in FIG. 1) in parallel with the pixel columns, and is connected to the drain electrode 10 of the TFT 6 in each column.

  Note that a terminal array portion (not shown) extending outward from the front substrate 1 is formed at an edge of the rear substrate 2, and the scanning line 12 and the signal line 13 are connected to the terminal array portion. Are connected to a plurality of scanning line terminals and signal line terminals.

  The common electrode 5 is formed on the gate insulating film 8, and the plurality of signal electrodes 4 cover the common electrode 5 and the TFT 6 and are formed on a transparent interlayer formed on substantially the entire surface of the rear substrate 2. It is formed on the insulating film 14. That is, the plurality of signal electrodes 4 and the common electrode 5 are insulated by the interlayer insulating film 14.

  Each of the plurality of signal electrodes 4 has a plurality of comb teeth along a longitudinal direction thereof in a vertically long rectangular region in which the vertical width (width in the vertical direction of the screen) is larger than the horizontal width (width in the horizontal direction of the screen). A transparent comb-shaped conductive film (for example, an ITO film) in which 4b is formed in parallel to each other at intervals, and a comb-teeth connection portion 4d that connects the plurality of comb-tooth portions 4b, 4b is formed on one end side in the longitudinal direction. 4a.

  As shown in FIG. 6, each comb tooth portion 4b of the comb-shaped conductive film 4a has a vertical direction of the screen, that is, a direction around either the left or right with respect to the vertical axis y of the screen, for example, the right side when viewed from the observation side. Of these comb teeth 4b, the comb teeth 4b (in FIG. 1) are not directly connected to the comb teeth connection 4d. The comb teeth 4b are formed in an elongated shape along the direction inclined at an angle θ of 5 ° to 15 ° in the rotation direction. The comb tooth portion 4b on the left end of the comb-shaped conductive film 4a is connected to the adjacent comb tooth portion at the end opposite to the comb connection portion 4d, and the comb is connected via the adjacent comb tooth portion 4b. It is connected to the tooth connecting part 4d.

  The ratio D2 / D1 between the width D1 of each comb tooth portion 4b of the comb-shaped conductive film 4a and the distance D2 between the adjacent comb tooth portions 4b and 4b is 1/3 to 3/1, preferably 1 / 1 is set.

  One end side of the comb-teeth connecting portion 4d of the comb-shaped conductive film 4a overlaps the source electrode 11 of the TFT 6 with the interlayer insulating film 14 interposed therebetween, and a contact (not shown) provided on the interlayer insulating film 14 The hole is connected to the source electrode 11.

  The common electrode 5 formed on the gate insulating film 8 is formed of a transparent row direction conductive film (for example, ITO film) 5a provided over the entire length of each pixel row, and the comb shape The signal electrode 4 made of the conductive film 4 a and the common electrode 5 made of the row direction conductive film 5 a, the edge 4 c of each comb tooth portion 4 b of the signal electrode 4, and each comb tooth portion of the common electrode 5 A lateral electric field E in a direction substantially parallel to the substrate surface of the rear substrate 2 is generated between a portion adjacent to the edge portion 4c of 4b (a portion corresponding to a portion between the adjacent comb teeth portions 4b and 4b). The horizontal electric field E forms a substantially vertically long rectangular pixel 100 that controls the orientation direction of the liquid crystal molecules 3a in a plane substantially parallel to the surfaces of the substrates 1 and 2.

  In this embodiment, as shown in FIG. 1, the row direction conductive film 5a is patterned into regions corresponding to the respective signal electrodes 4 made of the comb-shaped conductive film 4a to vertically long rectangular electrode portions 5b. These electrode portions 5b and 5b are formed in a shape connected by a connection portion 5c on one end side (the side opposite to the side on which the scanning line 12 is provided). You may form in the width | variety corresponding to the vertical width (width of the up-down direction of a screen) of the said pixel 100 over the full length of a line.

  The row direction conductive film 5 a is formed across the plurality of signal lines 13, and an intersection between the row direction conductive film 5 a and the signal line 13 is provided to cover the signal line 13. It is insulated by an insulating film (not shown).

  The plurality of row-direction conductive films 5a corresponding to the respective pixel rows are commonly connected (not shown) outside one end side of the array region of the plurality of signal electrodes 4, and the common connection portion is , And connected to a common electrode terminal provided in the terminal array portion of the rear substrate 2.

  On the other hand, light shielding films 15 corresponding to the regions between the plurality of pixels 100 and the plurality of TFTs 6 are formed on the inner surface of the front substrate 1 and correspond to the plurality of pixels 100 respectively. Three color filters 16R, 16G, and 16B of red, green, and blue are provided.

  The inner surfaces of the pair of substrates 1 and 2 cover the color filters 16R, 16G, and 16B provided on the front substrate 1 and the common electrode 5 provided on the rear substrate 2, respectively, and are made of a polyimide film or the like. Horizontal alignment films 17 and 18 are formed, and the inner surfaces of these substrates 1 and 2 are subjected to alignment treatment by rubbing the film surfaces of the alignment films 17 and 18 in parallel and in opposite directions. .

  The liquid crystal layer 3 is made of nematic liquid crystal having positive dielectric anisotropy, and the liquid crystal molecules 3a have molecular long axes defined by the alignment treatment direction of the inner surfaces of the pair of substrates 1 and 2. Are aligned substantially in parallel with the surfaces of the substrates 1 and 2 in a state where they are aligned in one predetermined direction and are slightly pretilted in that direction.

  The liquid crystal layer thickness d of the liquid crystal layer 3 is such that the product Δnd of the refractive index anisotropy Δn of the liquid crystal and the liquid crystal layer thickness d is a phase difference of ½ wavelength in the transmitted light. Is set to a value (approximately 275 nm).

  Further, the liquid crystal display element has a liquid crystal formed on the inner surface of the rear substrate 2 of the one substrate 1 or 2 by a horizontal electric field E generated between the plurality of pixels (the signal electrode 4 and the common electrode 5). The reflective film 19 is provided corresponding to each predetermined region in the region 100 in which the orientation direction of the molecules 3a is controlled.

  The reflection film 19 reflects the light incident on the respective pixels 100 from the observation side, that is, the outer surface side of the front substrate 1, and emits the light to the observation side, and the observation side A transmissive display portion 100b other than the reflective display portion that transmits light incident from the opposite side and emits the light to the observation side is formed.

Further, the inner surface of at least one of the pair of substrates 1 and 2, for example, the inner surface of the front substrate 1, is associated with the reflective display unit 100 a of the plurality of pixels 100, respectively. The liquid crystal layer thickness d ₁ is a value (about 137 nm) that gives the product a phase difference of ¼ wavelength to the transmitted light by the product Δnd ₁ of the refractive index anisotropy Δn of the liquid crystal of the reflective display unit 100 a and the liquid crystal layer thickness d _1. The liquid crystal layer thickness adjusting layer 20 is adjusted so as to adjust the thickness to (1).

That is, the liquid crystal layer thickness adjusting layer 20 has a thickness in which Δnd ₁ of the reflective display unit 100 a of the pixel 100 is smaller than a value corresponding to ¼ wavelength of transmitted light compared to Δnd ₂ of the transmissive display unit 100 b. Is formed. .

  The reflective film 19 is made of a metal film having a high light reflectance such as silver or an aluminum alloy film, and a predetermined region, for example, a rectangular shape, in the plurality of pixels 100 is formed on the substrate surface of the rear substrate 2. The pixel 100 having a shape is formed so as to correspond to a region on one end side from the center in the longitudinal direction.

  The liquid crystal layer thickness adjusting layer 20 is formed of a transparent insulating material on the color filters 15R, 15G, and 15B, and the alignment film 18 on the inner surface of the front substrate 1 is formed of the liquid crystal layer thickness adjusting layer. 20 is formed.

Then, in this liquid crystal display device, a liquid crystal layer thickness-adjusting layer 20, the liquid crystal layer thickness d ₁ of the reflective display portion 100a is transmissive display section 100b composed of other areas except for the reflective display part 100a of the pixel 100 The liquid crystal layer thickness d is approximately ½ of the liquid crystal layer thickness d, and Δnd ₁ of the reflective display portion 100a is set to about 137 nm which gives a phase difference of ¼ wavelength to the transmitted light.

Note that the liquid crystal layer thickness d ₂ of the transmissive display portion 100b of the plurality of pixels 100 is set so that Δnd _{2 of the} transmissive display portion 100b is about 275 nm that gives a half-wave phase difference to the transmitted light. It is.

That is, in this liquid crystal display element, in the gap between the pair of substrates 1 and 2, the liquid crystal molecules 3a are aligned substantially parallel to the surfaces of the substrates 1 and 2 with their molecular long axes aligned in one predetermined direction. The liquid crystal layer 3 is encapsulated, and arranged on the inner surface of the rear substrate 2 of the pair of substrates 1 and 2 so as to be insulated from each other, thereby generating a lateral electric field E substantially parallel to the surfaces of the substrates 1 and 2. In addition, a plurality of signal electrodes 4 and a plurality of common electrodes 5 for forming a plurality of pixels 100 in which the orientation direction of the liquid crystal molecules 3a is controlled by the lateral electric field E are arranged in a matrix, and A reflection display unit 100a that reflects light incident from the observation side and emits the light toward the observation side, corresponding to predetermined areas in the plurality of pixels 100 on the inner surface of the rear substrate 2, and the observation side, Transmits the light incident from the opposite side before A reflective film 19 for the transmissive display portion 100b other than the reflective display portion 100a is formed for each of the plurality of pixels 100 that emit the observation side provided, and, [Delta] nd of the transmissive display portion 100b of the plurality of pixels 100 ₂ Is set to a value (about 275 nm) that gives a half-wave phase difference to transmitted light, and the liquid crystal layer thickness adjusting layer 20 is provided on the inner surface of the front substrate 1, thereby reflecting the display of the plurality of pixels 100. Δnd ₁ of the part 100a is set to a value (137 nm) that gives the transmitted light a phase difference of ¼ wavelength.

  In this embodiment, the pair of polarizing plates 21 and 22 on the front side and the rear side respectively disposed on the outer surface of the front substrate 1 and the outer surface of the rear substrate 2 are made substantially parallel to the absorption axes thereof. A phase difference plate 23 for compensating the viewing angle dependency of the liquid crystal display element is disposed between the rear substrate 2 and the rear polarizing plate 22 disposed on the outer surface thereof.

  Further, the liquid crystal display element has a single film shape for blocking static electricity from the outside over the entire surface of the front substrate 1 between the front substrate 1 and the front polarizing plate 21 disposed on the outer surface thereof. A transparent electrostatic shielding conductive film 24 is provided.

  The alignment treatment direction (rubbing direction of the alignment films 17 and 18) 1a and 2a of the pair of substrates 1 and 2; the directions of the absorption axes 21a and 22a of the pair of polarizing plates 21 and 22; The direction of the slow axis 23a of the phase difference plate 23 is set as shown in FIG.

  That is, the inner surface of the front substrate 1 and the inner surface of the rear substrate 2 are opposite to each other along the horizontal direction of the screen, that is, the direction substantially shifted by 90 ° with respect to the horizontal axis x of the screen, that is, the vertical direction of the screen. The liquid crystal molecules 3a of the liquid crystal layer 3 are aligned substantially parallel to the surfaces of the substrates 1 and 2 with their molecular long axes aligned with the alignment treatment directions 1a and 2a of the substrates 1 and 2. is doing.

  The lateral electric field E generated between the signal electrode 4 and the common electrode 5 is in a direction substantially orthogonal to the length direction of the edge 4c of each comb tooth 4b of the signal electrode 4. In this embodiment, as described above, the comb-tooth portion 4b is inclined in the direction inclined clockwise by an angle θ of 5 ° to 15 ° with respect to the vertical axis y of the screen. The inner surfaces of the pair of substrates 1 and 2 (film surfaces of the alignment films 17 and 18) are aligned in a direction substantially parallel to the longitudinal axis y. The alignment processing directions 1a and 2a of 1 and 2 cross obliquely with respect to the direction of the transverse electric field E at an angle of 5 ° to 15 °.

  The front-side polarizing plate 21 and the rear-side polarizing plate 22 have the absorption axes 21a and 22a substantially parallel to each other, and these absorption axes 21a and 22a are set to the left and right with respect to the horizontal axis x of the screen. A liquid crystal in the absence of an electric field that does not generate a lateral electric field E between the signal electrode 4 and the common electrode 5, for example, a direction that is substantially shifted by 45 ° in a counterclockwise direction, for example, a counterclockwise direction when viewed from the observation side The molecules 3a are arranged so as to be substantially shifted by 45 ° with respect to the direction of the molecular major axis (the alignment processing directions 1a and 2a of the pair of substrates 1 and 2).

  The viewing angle dependency compensating phase difference plate 23 is a λ / 2 phase difference plate which gives a half-wave phase difference to transmitted light. The phase difference plate 23 has its slow axis 23a as the above-mentioned slow axis 23a. The rear polarizing plate 22 is disposed substantially parallel to the absorption axis 22a.

  The liquid crystal display element generates a lateral electric field E corresponding to display data between the plurality of signal electrodes 4 and the common electrode 5 provided on the inner surface of the rear substrate 2, thereby the liquid crystal molecules 3 a. The orientation direction is controlled in a plane substantially parallel to the surfaces of the substrates 1 and 2, and an image is displayed.

  The liquid crystal display element includes a plurality of regions formed on the inner surface of the rear substrate 2 and in which the orientation direction of the liquid crystal molecules 3 a is controlled by a lateral electric field E generated between the signal electrode 4 and the common electrode 5. The reflective display unit 100a that reflects the light incident from the observation side (the outer surface side of the front substrate 1) and emits the light toward the observation side corresponding to the predetermined regions in the pixel 100 is opposite to the observation side. Since the reflection film 19 for forming the transmissive display unit 100b other than the reflective display unit that transmits the light incident from the side and emits the light to the observation side is provided for each of the plurality of pixels 100, the reflection film 19 is provided from the observation side. Reflective display that reflects incident light and controls the emission of the light to the observation side to display an image, and the observation side of light incident from the opposite side (the outer surface side of the rear substrate 2) from the observation side The image is displayed by controlling the emission to the screen. It is possible to perform a display.

In addition, in this liquid crystal display element, Δnd ₂ of the transmissive display unit 100 b is set to a value that gives a phase difference of ½ wavelength to the transmitted light, and the inner surface of the front substrate 1 has the plurality of pixels 100. respectively to correspond to the reflective display portion 100a, the liquid crystal layer thickness _{d 1} of the reflective display unit 100a, [Delta] nd ₁ of the reflective display portion 100a is the transmitted light as compared to the [Delta] nd ₂ of the transmissive display section 100b 1/4 Since the liquid crystal layer thickness adjusting layer 20 for adjusting the thickness to a value that becomes smaller by a value corresponding to the wavelength, that is, a value that gives a phase difference of ¼ wavelength to the transmitted light is provided, the reflection display and the transmission display Can be performed without reversing light and dark.

  Further, in this liquid crystal display element, since the polarizing plates 21 and 22 on the opposite side to the observation side are arranged with their absorption axes 21a and 22a substantially parallel, the reflective display unit 100a and the transmissive display are arranged. Both displays of the unit 100b can be a non-field dark display (hereinafter referred to as a normally black display) in which the luminance is minimized when the lateral electric field E is not generated.

  That is, the liquid crystal molecules 3a of the liquid crystal layer 3 are arranged in the alignment processing directions 1a and 2a of the pair of substrates 1 and 2 as shown in FIG. As a result of the generation of the transverse electric field E, the angle of the molecular major axis with respect to the direction of the transverse electric field E in a plane substantially parallel to the surfaces of the substrates 1 and 2 as shown in FIG. Are arranged in the direction of decreasing.

  As described above, the lateral electric field E is generated between the edge 4c of each comb tooth 4b of the signal electrode 4 and the portion adjacent to the edge 4c of each comb tooth 4b of the common electrode 5. In between, it produces | generates along the direction substantially orthogonal to the length direction of the said comb-tooth part 4b.

  And each comb-tooth part 4b of the said signal electrode 4 is the direction which cross | intersects at the angle (theta) of 5 degrees-15 degrees with respect to the vertical axis | shaft y of a screen, ie, the alignment process direction 1a, 2a of a pair of said board | substrates 1 and 2. Therefore, the lateral electric field E is obliquely displaced at an angle of 65 ° to 85 ° in one direction with respect to the molecular long axis of the liquid crystal molecules 3a when no electric field is applied. The liquid crystal molecules 3a are uniformly rotated in a direction in which the angle of the molecular long axis with respect to the lateral electric field E is small in almost the entire region of the pixel 100 where the lateral electric field E is generated. Arrange the axes aligned.

  The arrangement direction of the liquid crystal molecules 3a when generating the horizontal electric field shown in FIG. 6B is substantially the same as that between the signal electrode 4 and the common electrode 5 with respect to the alignment treatment directions 1a and 2a. This is the direction when the transverse electric field E having a strength to be arranged in the direction of 45 ° is generated.

  In this liquid crystal display element, as shown in FIG. 5, the front polarizing plate 21 and the rear polarizing plate 22 have their respective absorption axes 21a and 22a oriented in the direction of the molecular major axis of the liquid crystal molecules 3a when there is no electric field. That is, it is arranged to be shifted by 45 ° in the clockwise direction when viewed from the observation side with respect to the vertical direction of the screen, and each comb tooth portion of the comb-shaped conductive film 4a is arranged in the vertical direction of the screen as shown in FIG. On the other hand, the liquid crystal molecules 3a are substantially 45 ° with respect to the alignment processing directions 1a and 2a by the generation of the transverse electric field E by forming the elongated shape along the direction inclined in the clockwise direction when viewed from the observation side. When aligned in the direction, the orientation of the molecular long axis is substantially perpendicular to the absorption axes 21 a and 22 a of the front polarizing plate 21 and the rear polarizing plate 22.

  The liquid crystal display element includes a reflective display that uses external light that is light from the external environment, and a transmissive display that uses illumination light from a surface light source (not shown) disposed on the opposite side of the liquid crystal display element from the observation side. In any display, the signal electrode 4 of each pixel 100 is connected to the liquid crystal molecules 3a between the signal electrode 4 and the common electrode 5 via the signal line 13 and the TFT 6. Display drive by applying a display data signal of a voltage value that generates a transverse electric field E that controls the orientation of the molecular long axis at an angle substantially in the range of 0 ° to 45 ° with respect to the alignment processing directions 1a and 2a. Is done.

  First, the reflective display will be described. At this time, external light incident on the liquid crystal display element from the observation side becomes linearly polarized light by the front polarizing plate 21 and enters the liquid crystal layer 3, and the light (front polarized light). Light that is incident on the reflective display portion 100a of each pixel 100 and transmitted through the liquid crystal layer 3 is reflected by the reflective film 19, and is reflected by the liquid crystal layer. 3 again and enters the front polarizing plate 21. The light incident on the transmissive display portion 100b of each pixel 100 is transmitted through the liquid crystal layer 3, and further transmitted through the viewing angle dependent compensation phase difference plate 23 and the rear polarizing plate 22, and opposite to the observation side. To the side.

  The Δnd of the reflective display unit 100a is set to a value that gives a quarter-wave phase difference to the transmitted light, and the alignment processing directions 1a and 2a of the pair of substrates 1 and 2 are the same as those of the front polarizing plate 21. Since it is substantially 45 ° offset from the absorption axis 21a, when there is no electric field, that is, when the liquid crystal molecules 3a are aligned in the alignment treatment directions 1a and 2a with their molecular long axes aligned, the reflective display of the pixel 100 is performed. The linearly polarized light incident on the portion 100a is rotated by 90 ° with a half-wave phase difference while passing back and forth through the liquid crystal layer 3, and is absorbed by the absorption axis 21a of the front polarizing plate 21. Linearly polarized light parallel to the light and absorbed by the front polarizing plate 21. Therefore, the display in the absence of an electric field of the reflective display unit 100a is a black dark display.

  Further, when the lateral electric field E having a strength for arranging the liquid crystal molecules 3a in the direction of 45 ° with respect to the alignment processing directions 1a and 2a is generated between the signal electrode 4 and the common electrode 5, that is, When the liquid crystal molecules 3a are aligned in a direction substantially orthogonal to the absorption axes 21a and 22a of the front polarizing plate 21 and the rear polarizing plate 22, the linearly polarized light incident on the reflective display unit 100a is The light passes back and forth through the liquid crystal layer 3 with almost no change in the polarization state, passes through the front polarizing plate 21 and exits to the observation side. Therefore, the display when the liquid crystal molecules 3a of the reflective display unit 100a are aligned in a direction of 45 ° with respect to the alignment processing directions 1a and 2a is the brightest bright display.

  Next, transmissive display will be described. At this time, illumination light emitted from a surface light source (not shown) toward the liquid crystal display element is linearly polarized by the rear polarizing plate 22 and the slow axis 23a is set to the slow axis 23a. The light (linearly polarized light orthogonal to the absorption axis 22a of the rear polarizing plate 22 is transmitted through the viewing angle dependent compensation phase difference plate 23 arranged substantially parallel to the absorption axis 22a of the rear polarizing plate 22. ), The light traveling toward the transmissive display portion 100b of each pixel 100 enters the liquid crystal layer 3. The light that has entered the reflective display portion 100a of each pixel 100 is reflected by the reflective film 19, and is transmitted again through the viewing angle dependent compensation phase difference plate 23 and the rear polarizing plate 22 to be the observation side. The light is emitted to the opposite side (surface light source side).

In addition, Δnd ₂ of the transmissive display unit 100b is set to a value that gives a phase difference of ½ wavelength to the transmitted light, and the alignment processing directions 1a and 2a of the pair of substrates 1 and 2 are the rear polarizing plate. 22 is substantially deviated by 45 ° with respect to the absorption axis 22a. Therefore, when there is no electric field, the transmissive display portion of the pixel 100 is transmitted through the rear polarizing plate 22 and the viewing angle dependent compensation phase difference plate 23. The linearly polarized light incident on 100b is substantially rotated by 90 ° while passing through the liquid crystal layer 3, and the absorption axis 21a is directed in a direction substantially parallel to the absorption axis 21a of the rear polarizing plate 22. It is absorbed by the arranged front polarizing plate 21. Therefore, the display of the transmissive display unit 100b when there is no electric field is black dark display.

  In addition, when a lateral electric field E is generated between the signal electrode 4 and the common electrode 5 such that the liquid crystal molecules 3a are arranged in a direction of 45 ° with respect to the alignment processing directions 1a and 2a (liquid crystal molecules). 3a is oriented in a direction substantially orthogonal to the absorption axes 21a and 22a of the front polarizing plate 21 and the rear polarizing plate 22), the linearly polarized light incident on the transmissive display portion 100b of the pixel 100 is The light passes through the liquid crystal layer 3 with almost no change in the polarization state, passes through the front polarizing plate 21 and exits to the observation side. Therefore, the display when the liquid crystal molecules 3a of the transmissive display unit 100b are arranged in a direction of 45 ° with respect to the alignment processing directions 1a and 2a is the brightest bright display.

  In addition, between the signal electrode 4 and the common electrode 5, a transverse electric field E having a strength for arranging the liquid crystal molecules 3a in a direction having an angle smaller than 45 ° with respect to the alignment processing directions 1a and 2a was generated. In some cases, the display of both the reflective display unit 100a and the transmissive display unit 100b is a display having a brightness intermediate between the black dark display and the brightest bright display.

  As described above, the display of the reflective display unit 100a and the display of the transmissive display unit 100b of each pixel 100 are both normally black display with dark display when no electric field is applied and bright display when horizontal electric field is generated. Therefore, a reflective display using external light and a transmissive display using illumination light from a surface light source arranged on the opposite side of the liquid crystal display element from the observation side can be performed without reversing the brightness of the display. In addition, when the illuminance of outside light is insufficient, the surface light source can be used as an auxiliary light source to perform display using both reflective display and transmissive display.

  In addition, the liquid crystal display element has substantially the polarizing plates 21 and 22 on the opposite side to the observation side, and the respective absorption axes 21a and 22a with respect to the direction of the molecular long axis of the liquid crystal molecules 3a when no electric field is applied. Since they are arranged at a 45 ° offset, in both the reflective display and the transmissive display, the light emission rate in the absence of an electric field is almost zero, the dark display is black, and the light in the horizontal electric field is generated. The emission rate can be substantially maximized to brighten the bright display sufficiently, and thus the brightness and contrast of both the reflective display and the transmissive display can be increased.

  Further, the liquid crystal display element includes a viewing angle dependency compensating retardation plate 23 between the rear substrate 2 and the rear polarizing plate 22, and a slow axis 23 a of the retardation axis 23 with the absorption axis 22 a of the rear polarizing plate 22. Since they are arranged substantially in parallel, the viewing angle dependency in the dark display is prevented from being lowered when the absorption axes 21a, 22a of the polarizing plates 21, 22 on the opposite side to the observation side are arranged in parallel to each other. Thus, the visual field of the transmissive display can be widened.

  The viewing angle dependency compensating retardation plate 23 may be arranged with its slow axis 23a substantially orthogonal to the absorption axis 22a of the rear polarizing plate 22, and in this case, the viewing angle of transmissive display is also provided. The dependence can be compensated and the field of view of the transmissive display can be widened.

  Further, the polarizing plates 21 and 22 on the opposite side to the observation side may have their absorption axes 21a and 22a arranged in a direction substantially orthogonal to the direction shown in FIG. Is the molecular length of the liquid crystal molecules 3a when the liquid crystal molecules 3a are aligned in a direction substantially 45 ° with respect to the alignment treatment directions 1a and 2a of the pair of substrates 1 and 2 by the generation of the transverse electric field E. Since the axes are substantially parallel to the absorption axes 21a and 22a of the front polarizing plate 21 and the rear polarizing plate 22, the reflective display and the transmissive display can be performed without reversing the brightness.

(Second Embodiment)
7 and 8 show a second embodiment of the present invention. FIG. 7 is a sectional view of a part of the liquid crystal display element, and FIG. 8 shows the orientation treatment direction of the inner surfaces of a pair of substrates of the liquid crystal display element. FIG. 5 is a view of the direction of the absorption axis of a pair of polarizing plates and the direction of the slow axis of a λ / 2 retardation plate as viewed from the observation side. In this embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals in the drawings, and the description thereof is omitted.

In the liquid crystal display element of this embodiment, the structure of the reflective display portion 100a and the transmissive display portion 100b of each pixel 100 and the Δnd ₁ and Δnd ₂ of the reflective display portion 100a and the transmissive display portion 100b are the same as in the first embodiment. In this embodiment, the pair of polarizing plates 21 and 22 on the opposite side to the observation side are arranged so that the absorption axes 21a and 22a are substantially orthogonal to each other. The viewing angle dependency compensating phase difference plate 23 is omitted, and a λ / 2 phase difference plate 25 that gives a phase difference of ½ wavelength to the transmitted light between the rear substrate 2 and the rear polarizing plate 22 is delayed. The shaft 25a is arranged so as to be substantially shifted from the absorption shaft 22a of the rear polarizing plate 22 by 45 °.

  In this liquid crystal display element, the pair of polarizing plates 21 and 22 has their absorption axes 21a and 22a aligned with the alignment treatment directions 1a and 2a of the pair of substrates 1 and 2, that is, the molecular length of the liquid crystal molecules 3a when no electric field is applied. The λ / 2 phase difference plate 25 is arranged so as to be shifted by 45 ° in directions opposite to each other with respect to the direction of the axis. Arranged substantially parallel to the orientation.

  In this embodiment, the orientation directions 1a and 2a of the pair of substrates 1 and 2 and the direction of the absorption axis 21a of the front polarizing plate 21 are the same as those in the first embodiment, and the rear polarizing plate 22 is The absorption axis 22a is arranged so as to be substantially orthogonal to the absorption axis 21a of the front polarizing plate 21.

  Since the liquid crystal display element has the above-described configuration, the reflective display and the transmissive display are performed without reversing the brightness, and both the reflective display unit 100a and the transmissive display unit 100b are normally displayed. In addition to black display, the field of view of the transmissive display can be widened.

  That is, the reflective display by the liquid crystal display element is the same as the reflective display by the liquid crystal display element of the first embodiment. When no electric field is applied, the reflective display unit 100a of each pixel 100 transmits the front polarizing plate 21. The incident linearly polarized light is substantially rotated by 90 ° while passing back and forth through the liquid crystal layer 3 and absorbed by the front polarizing plate 21, and liquid crystal molecules are interposed between the signal electrode 4 and the common electrode 5. When a lateral electric field E having a strength to align 3a in a direction substantially 45 ° with respect to the alignment treatment directions 1a and 2a is generated (the molecular long axis of the liquid crystal molecules 3a is the absorption axis 21a of the front polarizing plate 21) The linearly polarized light that has entered the reflective display portion 100a of the pixel 100 passes back and forth through the liquid crystal layer 3 almost without changing the polarization state, and the front polarized light. Observation side through plate 21 To exit.

  On the other hand, at the time of transmissive display, illumination light emitted from a surface light source (not shown) disposed on the opposite side of the liquid crystal display element from the observation side is converted into linearly polarized light by the rear polarizing plate 22 and further, The axis 25a is substantially rotated by 90 ° by the λ / 2 phase difference plate 25 arranged so as to be shifted by 45 ° with respect to the absorption axis 22a of the rear polarizing plate 22, and each pixel 100 out of the light is rotated. The light traveling toward the transmissive display unit 100 b enters the liquid crystal layer 3.

  The light that has been linearly polarized by the rear polarizing plate 22 and rotated by 90 ° by the λ / 2 phase difference plate 25 is linearly polarized light having a polarization plane parallel to the absorption axis 22a of the rear polarizing plate 22, That is, it is linearly polarized light having a polarization plane in a direction substantially inclined by 45 ° with respect to the direction of the molecular major axis of the liquid crystal molecules 3a when no electric field is applied.

Since Δnd ₂ of the transmissive display unit 100b is set to a value (275 nm) that gives a transmitted light a half-wave phase difference, the straight line incident on the transmissive display unit 100b when there is no electric field. Polarized light (light linearly polarized by the rear polarizing plate 22 and rotated by 90 ° by the λ / 2 retardation film 25) is further rotated by 90 ° in the process of passing through the liquid crystal layer 3, and the rear side The absorption axis 21 a of the polarizing plate 22 is incident on the front polarizing plate 21 as linearly polarized light that is substantially parallel, and is absorbed by the front polarizing plate 21.

  In addition, when a lateral electric field E having a strength for arranging the liquid crystal molecules 3a in a direction of 45 ° with respect to the alignment processing directions 1a and 2a is generated between the signal electrode 4 and the common electrode 5 (liquid crystal molecules 3a Is aligned in a direction substantially perpendicular to the absorption axis 21a of the front polarizing plate 21), the direction of the molecular long axis of the liquid crystal molecules 3a is the polarization of the linearly polarized light incident on the transmissive display unit 100b. Since it is substantially parallel to the surface, the linearly polarized light incident on the transmissive display unit 100b is transmitted through the liquid crystal layer 3 with almost no change in polarization state, and is transmitted through the front polarizing plate 21 and emitted to the observation side. To do.

  As described above, the display of the reflective display unit 100a and the display of the transmissive display unit 100b of each pixel 100 are both normally black display with dark display when no electric field is applied and bright display when horizontal electric field is generated. It is.

  In this liquid crystal display element, since the polarizing plates 21 and 22 on the opposite side to the observation side are arranged so that the absorption axes 21a and 22a are substantially orthogonal to each other, the viewing angle dependence of the transmissive display unit 100b is determined. Therefore, the visual field of the transmissive display can be widened.

  Further, in this liquid crystal display element, the polarizing plates 21 and 22 on the opposite side to the observation side are arranged so that the absorption axes 21a and 22a are opposite to each other in the direction of the molecular major axis of the liquid crystal molecules 3a when no electric field is applied. The λ / 2 phase difference plate 25 is arranged so as to be substantially shifted by 45 °, and the slow axis 25a thereof is arranged so as to be substantially parallel to the direction of the molecular long axis of the liquid crystal molecules 3a when no electric field is applied. Therefore, in both the reflective display and the transmissive display, the light emission rate when there is no electric field is set to almost zero, the dark display is black, and the light emission rate when generating a horizontal electric field is substantially maximized. Thus, the bright display can be sufficiently brightened, and therefore the brightness and contrast of both the reflective display and the transmissive display can be increased.

(Third embodiment)
9 and 10 show a third embodiment of the present invention. FIG. 9 is a sectional view of a part of the liquid crystal display element, and FIG. 10 shows the orientation treatment direction of the inner surfaces of a pair of substrates of the liquid crystal display element. FIG. 5 is a view of the direction of the absorption axis of a pair of polarizing plates and the direction of the slow axis of a λ / 2 retardation plate as viewed from the observation side.

In the liquid crystal display element of this embodiment, the structure of the reflective display portion 100a and the transmissive display portion 100b of each pixel 100 and the Δnd ₁ and Δnd ₂ of the reflective display portion 100a and the transmissive display portion 100b are the same as in the first embodiment. In this embodiment, the pair of polarizing plates 21 and 22 on the opposite side to the observation side are arranged so that the absorption axes 21a and 22a are substantially orthogonal to each other. The viewing angle dependency compensating phase difference plate 23 is omitted, and a λ / 2 phase difference plate 26 that gives a half-wave phase difference to transmitted light between the front substrate 1 and the front polarizing plate 21 is a slow axis thereof. 26a is substantially shifted by 45 ° with respect to the absorption axis 21a of the front polarizing plate 21.

  In this liquid crystal display element, the pair of polarizing plates 21 and 22 has their absorption axes 21a and 22a aligned with the alignment treatment directions 1a and 2a of the pair of substrates 1 and 2, that is, the molecular length of the liquid crystal molecules 3a when no electric field is applied. The λ / 2 phase difference plate 26 is arranged so as to be shifted by 45 ° in directions opposite to each other with respect to the direction of the axis. It is arranged so as to be substantially orthogonal to the direction.

  In this embodiment, the orientation directions 1a and 2a of the pair of substrates 1 and 2 and the direction of the absorption axis 21a of the front polarizing plate 21 are the same as those in the first embodiment, and the rear polarizing plate 22 is The absorption axis 22a is arranged so as to be substantially orthogonal to the absorption axis 21a of the front polarizing plate 21.

  Since the liquid crystal display element has the above-described configuration, the reflective display and the transmissive display are performed without reversing the brightness, and both the display on the reflective display unit 100a and the display on the transmissive display display unit 100b are performed. Can be made a normally black display, and the field of view of the transmissive display can be widened.

  That is, the reflective display by the liquid crystal display element will be described. At this time, the external light incident on the liquid crystal display element from the observation side is linearly polarized by the front polarizing plate 21, and the slow axis 26a is The light is substantially rotated by 90 ° by the λ / 2 phase difference plate 26 arranged so as to be shifted by 45 ° with respect to the absorption axis 21a of the front polarizing plate 21, and the light (to the absorption axis 21a of the front polarizing plate 21). Light that travels toward the reflective display portion 100 a of each pixel 100 is incident on the liquid crystal layer 3.

  The light linearly polarized by the front polarizing plate 21 and rotated by 90 ° by the λ / 2 phase difference plate 25 is linearly polarized light having a polarization plane parallel to the absorption axis 21a of the rear polarizing plate 21, that is, It is linearly polarized light having a polarization plane in a direction substantially inclined by 45 ° with respect to the direction of the molecular major axis of the liquid crystal molecules 3a when no electric field is applied.

Since Δnd ₁ of the reflective display unit 100a is set to a value (137 nm) that gives the transmitted light a ¼ wavelength phase difference, the straight line incident on the reflective display unit 100a when no electric field is applied. Polarized light (light linearly polarized by the front polarizing plate 21 and rotated by 90 ° by the λ / 2 phase difference plate 26) is substantially rotated by 90 ° while passing back and forth through the liquid crystal layer 3; The light is substantially rotated by 90 ° by the λ / 2 phase difference plate 26, becomes linearly polarized light parallel to the absorption axis 21 a of the front polarizing plate 21, and is absorbed by the front polarizing plate 21.

  In addition, when a lateral electric field E having a strength for arranging the liquid crystal molecules 3a in a direction of 45 ° with respect to the alignment processing directions 1a and 2a is generated between the signal electrode 4 and the common electrode 5 (liquid crystal molecules 3a Is aligned in a direction substantially perpendicular to the absorption axis 21a of the front polarizing plate 21), the direction of the molecular long axis of the liquid crystal molecules 3a is the polarization of the linearly polarized light incident on the reflective display portion 100a. Since it is substantially orthogonal to the plane, the linearly polarized light incident on the reflective display portion 100a passes back and forth through the liquid crystal layer 3 almost without changing the polarization state, and is further substantially transmitted by the λ / 2 retardation plate 26. Thus, the light is rotated by 90 ° to become linearly polarized light substantially orthogonal to the absorption axis 21a of the front polarizing plate 21, passes through the front polarizing plate 21, and exits to the observation side.

  On the other hand, during transmissive display, illumination light emitted from a surface light source (not shown) disposed on the opposite side of the liquid crystal display element from the observation side is converted into linearly polarized light by the rear polarizing plate 22 and the light (rear) Of the linearly polarized light orthogonal to the absorption axis 22 a of the side polarizing plate 22, light traveling toward the transmissive display unit 100 b of each pixel 100 is incident on the liquid crystal layer 3.

  The light linearly polarized by the rear polarizing plate 22 is linearly polarized light having a polarization plane in a direction substantially inclined by 45 ° with respect to the direction of the molecular major axis of the liquid crystal molecules 3a when no electric field is applied. is there.

Since Δnd ₂ of the transmissive display unit 100b is set to a value (275 nm) that gives a transmitted light a half-wave phase difference, the straight line incident on the transmissive display unit 100b when there is no electric field. Polarized light (light linearly polarized by the rear polarizing plate 22) is substantially rotated by 90 ° while passing through the liquid crystal layer 3, and further rotated by 90 ° by the λ / 2 phase difference plate 26. Thus, the linearly polarized light becomes substantially parallel to the absorption axis 21 a of the front polarizing plate 21 and is absorbed by the front polarizing plate 21.

  In addition, when a lateral electric field E having a strength for arranging the liquid crystal molecules 3a in a direction of 45 ° with respect to the alignment processing directions 1a and 2a is generated between the signal electrode 4 and the common electrode 5 (liquid crystal molecules 3a Is aligned in a direction substantially perpendicular to the absorption axis 21a of the front polarizing plate 21), the direction of the molecular long axis of the liquid crystal molecules 3a is the polarization of the linearly polarized light incident on the transmissive display unit 100b. Since it is substantially perpendicular to the plane, the linearly polarized light incident on the transmissive display portion 100b is transmitted through the liquid crystal layer 3 with almost no change in polarization state, and is substantially 90 ° by the λ / 2 retardation plate 26. The light is rotated to become linearly polarized light substantially orthogonal to the absorption axis 21 a of the front polarizing plate 21, passes through the front polarizing plate 21, and exits to the observation side.

  As described above, the display of the reflective display display unit 100a and the display of the transmissive display display unit 100b of each of the pixels 100 are both normally displayed with no display when no electric field is displayed and displayed bright when a horizontal electric field is generated. Black display.

  In this liquid crystal display element, since the polarizing plates 21 and 22 on the opposite side to the observation side are arranged so that the absorption axes 21a and 22a are substantially orthogonal to each other, the viewing angle dependence of the transmissive display unit 100b is determined. Therefore, the visual field of the transmissive display can be widened.

  Further, in this liquid crystal display element, the polarizing plates 21 and 22 on the opposite side to the observation side are arranged so that the absorption axes 21a and 22a are opposite to each other in the direction of the molecular major axis of the liquid crystal molecules 3a when no electric field is applied. The λ / 2 phase difference plate 26 is arranged so as to be substantially shifted by 45 °, and the slow axis 26a thereof is arranged so as to be substantially orthogonal to the direction of the molecular long axis of the liquid crystal molecules 3a when no electric field is applied. Therefore, in both the reflective display and the transmissive display, the light emission rate when there is no electric field is set to almost zero, the dark display is black, and the light emission rate when generating a horizontal electric field is substantially maximized. Thus, the bright display can be sufficiently brightened, and therefore the brightness and contrast of both the reflective display and the transmissive display can be increased.

(Other embodiments)
The liquid crystal display elements of the first to third embodiments described above are provided with the signal electrode 4 made of the comb-shaped conductive film 4a. The signal electrode 4 has a slit in which a plurality of slits are formed in parallel to each other. You may form with a electrically conductive film.

  Further, in each of the above embodiments, the common electrode 5 is provided on the substrate 2 side of the inner surface of the rear substrate 2 on the substrate 2 side so as to be insulated from the signal electrode 4, but the signal electrode connected to the TFT 6 is provided. Alternatively, a conductive electrode having a shape corresponding to the pixel region may be formed, and a common electrode made of a comb-shaped conductive film or a conductive film with a slit may be provided on the liquid crystal layer side of the signal electrode so as to be insulated from the signal electrode.

  Further, in each of the above embodiments, the plurality of signal electrodes 4 and the common electrode 5 are provided on the inner surface of the rear substrate 2. However, the signal electrode 4 and the common electrode 5 may be provided on the inner surface of the front substrate 1. In addition, the reflective film 19 that divides the pixel 100 into the reflective display part 100 a and the transmissive display part 100 b may be provided on the inner surface of the rear substrate 2.

  In each of the above embodiments, the liquid crystal layer thickness adjusting layer 20 is provided on the inner surface of the front substrate 1. However, the liquid crystal layer thickness adjusting layer 20 may be provided on the inner surface of the rear substrate 2 or a pair of substrates. You may provide in the inner surface of both of 1 and 2.

1 is a plan view of a part of one substrate of a liquid crystal display device showing a first embodiment of the present invention; Sectional drawing which follows the II-II line | wire of FIG. 1 of the liquid crystal display element of a 1st Example. Sectional drawing which follows the II-II line | wire of FIG. 1 of the liquid crystal display element of a 1st Example. Sectional drawing which follows the IV-IV line | wire of FIG. 1 of the liquid crystal display element of a 1st Example. The figure which looked at the orientation processing direction of a pair of board | substrate of the liquid crystal display element of 1st Example, the direction of the absorption axis of a pair of polarizing plate, and the direction of the slow axis of a viewing angle dependence compensation phase difference plate from the observation side. . The figure which looked at the direction of the molecular long axis of the liquid crystal molecule from the observation side at the time of no electric field and horizontal electric field generation in one pixel of the liquid crystal display element. Sectional drawing of the part of liquid crystal display element which shows 2nd Example of this invention. The orientation processing direction of the inner surfaces of the pair of substrates of the liquid crystal display element of the second embodiment, the direction of the absorption axis of the pair of polarizing plates, and the direction of the slow axis of the λ / 2 retardation plate were viewed from the observation side. Figure. The top view of a part of liquid crystal display element which shows the 3rd Example of this invention. The orientation processing direction of the inner surfaces of the pair of substrates of the liquid crystal display element of the third example, the direction of the absorption axis of the pair of polarizing plates, and the direction of the slow axis of the λ / 2 retardation plate were viewed from the observation side. Figure.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Front board | substrate (observation side board | substrate), 2 ... Back board | substrate (opposite side board | substrate), 1a, 2a ... Orientation process direction, 3 ... Liquid crystal layer, 3a ... Liquid crystal molecule, 4 ... Signal electrode, 4a ... Comb-shaped electrically conductive film, 4b ... comb tooth part, 5 ... common electrode, 5a ... row direction conductive film, 5b ... electrode part, 6 ... TFT (active element), 7 ... gate electrode (control electrode), 8 ... gate insulating film, 9 ... i-type semiconductor Membrane, 10 ... Drain electrode (input electrode), 11 ... Source electrode (output electrode), 12 ... Scanning line, 13 ... Signal line, 14 ... Interlayer insulating film, 15 ... Light shielding film, 16R, 16G, 16B ... Color filter, 17, 18 ... Alignment film, 19 ... Reflective film, 20 ... Liquid crystal layer thickness adjusting layer, 21 ... Front side (observation side) polarizing plate, 21a ... Absorption axis, 22 ... Rear side (opposite side) polarizing plate, 22a ... Absorption axis , 23 ... Viewing angle dependent compensation phase difference plate, 23a ... Slow axis, 24 ... Electrostatic shielding conductive film, 5,26 ... λ / 2 phase plate, 25a, 26a ... slow axis, 100 ... pixel, 100a ... reflective display portion, 100b ... transmissive display unit.

Claims (2)

A pair of substrates on the opposite side and the observation side disposed opposite each other with a predetermined gap;
A liquid crystal layer encapsulated in a gap between the pair of substrates, wherein the liquid crystal molecules are aligned substantially parallel to the substrate surface with their molecular long axes aligned in one predetermined direction;
Insulated on either one of the opposing inner surfaces of the pair of substrates, generates a lateral electric field substantially parallel to the substrate surface, and the orientation of the liquid crystal molecules is controlled by the lateral electric field A plurality of signal electrodes and a plurality of common electrodes for forming a plurality of pixels arranged in a matrix,
A reflective display unit provided on an inner surface or an outer surface of the substrate on the opposite side so as to correspond to a predetermined region in each of the plurality of pixels, which reflects light incident from the observation side and emits the light to the observation side; A reflective film for forming a transmissive display unit other than the reflective display unit that transmits light incident from the opposite side to the observation side and emits the light to the observation side; and
The inner surface of at least one of the pair of substrates is provided so as to correspond to the reflective display portion of the plurality of pixels, and the refractive index anisotropy Δn of the liquid crystal and the liquid crystal layer thickness d of the reflective display portion, Is reduced by a value corresponding to a quarter wavelength of transmitted light as compared to the product Δnd of the refractive index anisotropy Δn of the liquid crystal and the liquid crystal layer thickness d of the transmissive display unit. A liquid crystal layer thickness adjusting layer for adjusting the liquid crystal layer thickness of the display unit;
A pair of polarizing plates on the outer side of the pair of substrates, on the observation side and on the opposite side, each arranged substantially parallel to the respective absorption axes ;
A retardation plate having a slow axis substantially parallel to the absorption axis of the opposite polarizing plate between the substrate opposite to the observation side and the opposite polarizing plate disposed on the outer surface thereof;
A liquid crystal display element comprising: 2. The liquid crystal display according to claim 1 , wherein the pair of polarizing plates are arranged such that their absorption axes are substantially shifted by 45 ° with respect to the direction of the molecular long axis of the liquid crystal molecules when there is no electric field. element.

Images