Display device

Abstract

To provide a display device that has a reflection type liquid crystal display element and a spontaneous light display element for each element, and suppresses deterioration of the spontaneous light display element.SOLUTION: A display device includes a first board having a switching element and a second board having a liquid crystal layer and a counter electrode in this order, and includes multiple pixels, the multiple pixels include a reflection liquid crystal section and a spontaneous light element section each, the first board has a reflection plate, a coating layer, and a pixel electrode in this order toward the liquid crystal layer side in the reflection liquid crystal section, no switching elements are provided, the reflection plate, the pixel electrode, the liquid crystal layer, and the counter electrode compose a reflection type liquid crystal display element in a bistable type liquid crystal display mode, the first board has the switching element, a spontaneous light display element, and the coating layer disposed in the liquid crystal layer side of the spontaneous light display element in the spontaneous light element section, and the coating layer is provided continuously in the reflection liquid crystal section and the spontaneous light element section.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a display device. [Background technology]

[0002] 2. Description of the Related Art Conventionally, various display devices such as liquid crystal display devices and organic electroluminescence (EL: Electro-Luminescence) display devices have been widely used as display devices for displaying videos (moving images and still images).

[0003] For example, a liquid crystal display device is a display device that uses a liquid crystal composition for display, and a typical display method thereof has a TFT substrate equipped with thin film transistors (TFTs), a counter substrate disposed opposite the TFT substrate, and a liquid crystal layer sealed between the TFT substrate and the counter substrate.

[0004] Liquid crystal display devices are broadly classified into reflective and transmissive types according to the method of transmitting light to the liquid crystal layer. Reflective liquid crystal display devices have a reflector inside the device, which reflects incident light from the outside and transmits the reflected light through the liquid crystal layer to display an image. Transmissive liquid crystal display devices display an image by transmitting light emitted from a backlight unit arranged on the rear side of the liquid crystal display device through the liquid crystal layer. Reflective liquid crystal display devices do not require a backlight unit, and therefore can achieve low power consumption, thinness, and weight reduction. On the other hand, transmissive liquid crystal display devices have a light source on the rear side of the liquid crystal display device, and therefore have good visibility even in dark environments.

[0005] An organic EL display device is a self-luminous display device, and includes, for example, a TFT substrate on which TFTs are provided, an organic EL element provided on the TFT substrate and connected to the TFT, and a sealing substrate arranged to cover the organic EL element. An organic EL display device for full-color display generally includes organic EL elements of three colors, red (R), green (G), and blue (B), as sub-pixels, which are arranged in a matrix, and each pixel is composed of the sub-pixels of the three colors. An image is displayed by selectively causing these organic EL elements to emit light at a desired luminance.

[0006] As a technology related to a display device, for example, Patent Document 1 discloses a display device having a TFT substrate having an insulating layer formed on a driving element, a liquid crystal layer containing a liquid crystal composition, a counter substrate having a transparent electrode facing the TFT substrate via the liquid crystal layer, and a polarizing plate provided on the opposite surface of the counter substrate to the surface facing the liquid crystal layer, the display device having a plurality of pixels each consisting of a first region and a second region adjacent to each other in a display region, the first region having a reflective electrode above the insulating layer of the TFT substrate, the second region having a light-emitting element in which a first electrode, an organic layer, and a second electrode are laminated on the insulating layer of the TFT substrate, the light-emitting element has a covering layer covering the entire light-emitting region of each pixel, and the edge of the covering layer is joined to the insulating layer. Patent Documents 2 and 3 are also disclosed as technologies related to a display device. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] U.S. Pat. No. 1,054,7026 [Patent Document 2] Patent No. 4530217 [Patent Document 3] Patent No. 4942898 Summary of the Invention [Problem to be solved by the invention]

[0008] Fig. 21 is a schematic cross-sectional view of a pixel included in the display device of Patent Document 1. Patent Document 1 discloses a composite (hybrid) display device that combines a reflective liquid crystal display element and a self-luminous display element. As shown in Fig. 21, the hybrid display type display device 1R of Patent Document 1 includes a reflective liquid crystal display element 20R and a self-luminous display element 30R for each pixel 1PR, and can improve visibility outdoors under direct sunlight, as well as visibility indoors and at night.

[0009] More specifically, the display device 1R has a first substrate 100R having an insulating film 105R provided on thin film transistors (TFTs) (specifically, a current supply TFT 12R and a switch TFT 13R) serving as driving elements (switching elements), a liquid crystal layer 22R containing liquid crystal molecules 22AR, a second substrate 200R facing the first substrate 100R via the liquid crystal layer 22R and equipped with a counter electrode 23R, and a circular polarizer 25R provided on the surface of the second substrate 200R opposite to the surface facing the liquid crystal layer 22R.

[0010] The display device 1R has a plurality of pixels 1PR, each of which is made up of a reflective liquid crystal portion 1AR and a self-luminous element portion 1BR adjacent to each other, within a display region.

[0011] In the reflective liquid crystal section 1AR, the first substrate 100R includes, in order toward the liquid crystal layer 22R, a first support substrate 101R, a source electrode 13SR, a semiconductor layer 102AR, a drain electrode 13DR, a gate insulating film 103R, a gate electrode 13GR, an inorganic insulating film 104R, an insulating film 105R, a liquid crystal element-side insulating film 32aR, and a reflective electrode 21R. The source electrode 13SR, the gate electrode 13GR, the drain electrode 13DR, and the semiconductor layer 102AR constitute a switching TFT 13R. The reflective electrode 21R, the liquid crystal layer 22R, the counter electrode 23R, and the circular polarizer 25R arranged in the reflective liquid crystal section 1AR constitute a reflective liquid crystal display element 20R.

[0012] In the self-luminous element section 1BR, the first substrate 100R includes, in order toward the liquid crystal layer 22R side, a first support substrate 101R, a source electrode 12SR, a semiconductor layer 102BR, a drain electrode 12DR, a gate insulating film 103R, a gate electrode 12GR, an inorganic insulating film 104R, an insulating film 105R, a first electrode 31R, a self-luminous element side insulating film 32R, an organic layer 33R, a second electrode 34R, and a covering layer 35R. The source electrode 12SR, the gate electrode 12GR, the drain electrode 12DR, and the semiconductor layer 102BR constitute a current supply TFT 12R. The first electrode 31R, the organic layer 33R, and the second electrode 34R constitute a self-luminous display element 30R. The covering layer 35R covers the entire self-luminous display element 30R for each pixel 1PR, and is also called a sealing layer.

[0013] The self-emission element side insulating film 32R is an insulating film called an insulating bank that defines a light-emitting region. The self-emission element side insulating film 32R is provided on the insulating film 105R of the reflective liquid crystal section 1AR with the same material and with approximately the same thickness, but is separated from the self-emission element side insulating film 32R called an insulating bank of the self-emission element section 1BR, so that the self-emission element side insulating film 32R in the reflective liquid crystal section 1AR is called a liquid crystal element side insulating film 32aR.

[0014] The second substrate 200R includes, in this order toward the liquid crystal layer 22R, a second support substrate 201R, a color filter layer 24R, and a counter electrode 23R.

[0015] In the reflective liquid crystal display element 20R, a TFT drive or memory in pixel (MIP) structure is applied, and it is necessary to connect the reflective electrode 21R to a switching TFT 13R or a memory circuit provided in the same layer as the drive circuit (current supply TFT 12R) arranged in the self-luminous element section 1BR.

[0016] In the display device 1R, in order to connect the reflective electrode 21R provided in the reflective liquid crystal section 1AR to the switching TFT 13R, the covering layer 35R is not provided in the reflective liquid crystal section 1AR, and only the self-luminous display element 30R is sealed with the covering layer 35R, and it is necessary to provide a contact hole 11CHR in the liquid crystal element side insulating film 32aR arranged below the reflective electrode 21R in the reflective liquid crystal section 1AR. At this time, since the covering layer 35R is formed in an island shape, a boundary of the covering layer 35R is generated for each pixel 1PR, and moisture or the like may enter from the boundary, causing deterioration of the self-luminous display element 30R. Thus, in the display device 1R, the sealing of the self-luminous display element 30R is insufficient, and therefore the life of the display device 1R may be shortened.

[0017] The present invention has been made in consideration of the above-mentioned current situation, and aims to provide a display device that has a reflective liquid crystal display element and a self-luminous display element for each pixel, and in which deterioration of the self-luminous display element is suppressed. [Means for solving the problem]

[0018] (1) One embodiment of the present invention is a display device comprising, in order, a first substrate having a switching element, a liquid crystal layer including liquid crystal molecules, and a second substrate having a counter electrode, and comprising a plurality of pixels arranged in a matrix in a display region, each of the plurality of pixels including a reflective liquid crystal section and a self-luminous element section, in which the first substrate includes a reflector, a covering layer, and a pixel electrode, in that order, toward the liquid crystal layer, and does not include a switching element, and the reflector, the pixel electrode, the liquid crystal layer, and the counter electrode constitute a reflective liquid crystal display element of a bistable liquid crystal display mode, and in which the self-luminous element section includes the first substrate including the switching element, a self-luminous display element including a first electrode, an organic layer, and a second electrode, and the covering layer arranged on the liquid crystal layer side of the self-luminous display element, and the covering layer is provided continuously over the reflective liquid crystal section and the self-luminous element section.

[0019] (2) Furthermore, in one embodiment of the present invention, in addition to the configuration of (1) above, the display device further comprises a non-display area provided around the display area and wiring provided in the non-display area of ​​the first substrate, wherein the counter electrode and the wiring are connected in the non-display area, and the pixel electrode and the wiring are connected.

[0020] (3) Furthermore, in one embodiment of the present invention, in addition to the configuration of (1) or (2) above, the liquid crystal layer is in one of a first stable state and a second stable state in which the orientation states of the liquid crystal molecules are different from each other when a voltage less than a threshold value is applied between the pixel electrode and the counter electrode, and the first stable state and the second stable state can be switched by applying a pulse waveform voltage between the pixel electrode and the counter electrode.

[0021] (4) Moreover, in one embodiment of the present invention, in addition to the configuration of (1), (2), or (3), the covering layer is provided continuously over the plurality of pixels.

[0022] (5) Furthermore, an embodiment of the present invention is a display device having the configuration of (1), (2), (3), or (4) above, wherein the reflector is disposed in the same layer as the first electrode.

[0023] (6) In addition to the configuration of (1), (2), (3), (4) or (5), an embodiment of the present invention further comprises a vertical alignment film disposed between the first substrate and the liquid crystal layer, and a grating layer disposed between the second substrate and the liquid crystal layer, wherein the liquid crystal layer is in one of a first stable state in which the liquid crystal molecules are vertically aligned and a second stable state in which the liquid crystal molecules are HAN aligned when no voltage is applied, in which a voltage less than a threshold value is applied between the pixel electrode and the counter electrode, and the first stable state and the second stable state can be switched by applying a pulse waveform voltage between the pixel electrode and the counter electrode.

[0024] (7) Furthermore, in one embodiment of the present invention, in addition to the configuration of (6), a pretilt angle of the liquid crystal molecules on the first substrate side in the first stable state is not less than 85° and not more than 90°, and a pretilt angle of the liquid crystal molecules on the second substrate side is not less than 85° and not more than 90°.

[0025] (8) Furthermore, in an embodiment of the present invention, in addition to the configuration of (6) or (7), a pretilt angle of the liquid crystal molecules on the first substrate side in the second stable state is not less than 85° and not more than 90°, and a pretilt angle of the liquid crystal molecules on the second substrate side is not less than 0° and not more than 5°.

[0026] (9) Furthermore, in an embodiment of the present invention, in addition to the configuration of (1), (2), (3), (4) or (5), the display device further comprises a horizontal alignment film having a pretilt arranged between the first substrate and the liquid crystal layer, and a grating layer arranged between the second substrate and the liquid crystal layer, wherein the liquid crystal layer is in one of a first stable state in which the liquid crystal molecules are in a TN orientation and a second stable state in which the liquid crystal molecules are in a HAN orientation when no voltage is applied and a voltage less than a threshold value is applied between the pixel electrode and the counter electrode, and the first stable state and the second stable state can be switched by applying a pulse waveform voltage between the pixel electrode and the counter electrode.

[0027] (10) Furthermore, in an embodiment of the present invention, in addition to the configuration of (9), in the first stable state, a pretilt angle of the liquid crystal molecules on the first substrate side is 3° or more and 5° or less, a pretilt angle of the liquid crystal molecules on the second substrate side is 0° or more and 5° or less, and in a planar view, an angle between an alignment direction of the liquid crystal molecules on the first substrate side and an alignment direction of the liquid crystal molecules on the second substrate side is 80° or more and 90° or less.

[0028] (11) Furthermore, in an embodiment of the present invention, in addition to the configuration of (9) or (10), a pretilt angle of the liquid crystal molecules on the first substrate side in the second stable state is not less than 3° and not more than 5°, and a pretilt angle of the liquid crystal molecules on the second substrate side is not less than 85° and not more than 90°.

[0029] (12) In addition, in one embodiment of the present invention, in addition to the configuration of (1), (2), (3), (4) or (5), the display device further comprises a weak anchoring alignment film arranged between the first substrate and the liquid crystal layer, and a strong anchoring alignment film arranged between the second substrate and the liquid crystal layer, wherein the liquid crystal layer is in one of a first stable state in which the liquid crystal molecules are homogeneously aligned, and a second stable state in which the liquid crystal molecules on the first substrate side are twisted in a planar view by 180° rotation from the first stable state, when no voltage is applied and a voltage less than a threshold value is applied between the pixel electrode and the counter electrode, and the first stable state and the second stable state can be switched by applying a pulse waveform voltage between the pixel electrode and the counter electrode.

[0030] (13) Furthermore, in an embodiment of the present invention, in addition to the configuration of (12), in the first stable state, a pretilt angle of the liquid crystal molecules on the first substrate side is 0° or more and 5° or less, a pretilt angle of the liquid crystal molecules on the second substrate side is 5° or more and 10° or less, and in a planar view, an angle between an alignment direction of the liquid crystal molecules on the first substrate side and an alignment direction of the liquid crystal molecules on the second substrate side is 0° or more and 10° or less.

[0031] (14) Furthermore, in an embodiment of the present invention, in addition to the configuration of (12) or (13), in the second stable state, a pretilt angle of the liquid crystal molecules on the first substrate side is 0° or more and 5° or less, a pretilt angle of the liquid crystal molecules on the second substrate side is 5° or more and 10° or less, an angle between an alignment direction of the liquid crystal molecules on the first substrate side and an alignment direction of the liquid crystal molecules on the second substrate side is 0° or more and 10° or less in a planar view, and the liquid crystal molecules are twisted and aligned by 170° or more and 180° or less in-plane from the first substrate side to the second substrate side.

[0032] (15) Furthermore, in one embodiment of the present invention, in addition to the configuration of (1), (2), (3), (4), (5), (6), (7), (8), (9), (10), (11), (12), (13) or (14), the reflector has an uneven shape on the surface facing the liquid crystal layer. Effect of the Invention

[0033] According to the present invention, it is possible to provide a display device which includes a reflective liquid crystal display element and a self-luminous display element for each pixel, and in which deterioration of the self-luminous display element is suppressed. [Brief description of the drawings]

[0034] [Figure 1] 1 is a cross-sectional view illustrating a pixel included in the display device of Embodiment 1. FIG. [Figure 2A] 1 is a schematic plan view of a display device according to a first embodiment. [Figure 2B] 2B is an enlarged schematic plan view of the area surrounded by the dashed line in FIG. 2A. FIG. [Diagram 3] 2 is an equivalent circuit diagram of the TFTs and wiring arranged on the first substrate in FIG. 1. [Figure 4] 4 is a schematic cross-sectional view illustrating a connection between a counter electrode and wiring in a non-display region of the display device of Embodiment 1. FIG. [Diagram 5] 4 is a schematic cross-sectional view illustrating the connection between pixel electrodes and wiring in a non-display region of the display device of Embodiment 1. FIG. [Figure 6] FIG. 2 is a cross-sectional view illustrating a case where liquid crystal molecules in the display device of the first embodiment are in a homeotropic alignment. [Figure 7] 4 is a diagram showing a first pulse waveform of a voltage applied between a pixel electrode and a counter electrode included in the display device of Embodiment 1. FIG. [Figure 8] 3 is a cross-sectional view illustrating a case where liquid crystal molecules in the display device of the first embodiment are in a HAN orientation. FIG. [Figure 9] 10 is a diagram showing a second pulse waveform of a voltage applied between a pixel electrode and a counter electrode included in the display device of Embodiment 1. FIG. [Figure 10] 1 is a cross-sectional view illustrating a pixel included in a display device according to a second embodiment of the present invention. FIG. [Figure 11] FIG. 11 is a cross-sectional view illustrating a case where liquid crystal molecules in the display device of Embodiment 2 have a TN orientation. [Figure 12] 10 is a diagram showing a first pulse waveform of a voltage applied between a pixel electrode and a counter electrode included in the display device of Embodiment 2. FIG. [Figure 13] 10 is a cross-sectional view illustrating a case where liquid crystal molecules in the display device of Embodiment 2 are in a HAN orientation. FIG. [Figure 14] 13 is a diagram showing a second pulse waveform of a voltage applied between a pixel electrode and a counter electrode included in the display device of Embodiment 2. FIG. [Figure 15] 11 is a cross-sectional view illustrating a pixel of the display device according to the third embodiment. FIG. [Figure 16] FIG. 11 is a cross-sectional view illustrating a case where liquid crystal molecules in the display device of the third embodiment are aligned in a homogeneous manner. [Figure 17] 13 is a diagram showing a first pulse waveform of a voltage applied between a pixel electrode and a counter electrode included in the display device of Embodiment 3. FIG. [Figure 18] 11 is a cross-sectional view illustrating a case where liquid crystal molecules in the display device of Embodiment 3 are in a twisted alignment. FIG. [Figure 19] 13 is a diagram showing a second pulse waveform of a voltage applied between a pixel electrode and a counter electrode included in the display device of Embodiment 3. FIG. [Figure 20] 11 is a cross-sectional view illustrating a pixel of the display device according to the fourth embodiment. FIG. [Figure 21] FIG. 1 is a cross-sectional view illustrating a pixel included in the display device of Patent Document 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] Hereinafter, an embodiment of the present invention will be described. The present invention is not limited to the contents described in the following embodiment, and appropriate design changes can be made within the scope of the configuration of the present invention. In the following description, the same reference numerals are appropriately used in common between different drawings for the same parts or parts having similar functions, and repeated explanations thereof will be omitted as appropriate. Each aspect of the present invention may be appropriately combined within the scope of the gist of the present invention.

[0036] (Embodiment 1) Fig. 1 is a cross-sectional schematic diagram of a pixel included in the display device of embodiment 1. Fig. 2A is a plan schematic diagram of the display device of embodiment 1. Fig. 2B is an enlarged plan schematic diagram of a region surrounded by a dashed line in Fig. 2A. Fig. 3 is an equivalent circuit diagram of TFTs and wiring arranged on the first substrate in Fig. 1.

[0037] 1 to 3, the display device 1 of this embodiment includes a first substrate 100 having switching elements, a liquid crystal layer 22 including liquid crystal molecules 22A, and a second substrate 200 having a counter electrode 23, in that order, and includes a plurality of pixels 1P arranged in a matrix in a display region 10A, and each of the plurality of pixels 1P includes a reflective liquid crystal section 1A and a self-luminous element section 1B. In the reflective liquid crystal section 1A, the first substrate 100 includes a reflector 21X, a coating layer 35, and a pixel electrode 21, in that order, toward the liquid crystal layer 22 side, and does not include switching elements. The reflector 21X, the pixel electrode 21, the liquid crystal layer 22, and the counter electrode 23 constitute a reflective liquid crystal display element 20 in a bistable liquid crystal display mode. In the self-luminous element section 1B, the first substrate 100 includes a current supply thin film transistor (TFT) 12 as the switching element, a self-luminous display element 30 including a first electrode 31, an organic layer 33, and a second electrode 34, and a covering layer 35 disposed on the liquid crystal layer 22 side of the self-luminous display element 30. The covering layer 35 is provided continuously on the reflective liquid crystal section 1A and the self-luminous element section 1B.

[0038] The reflector 21X, pixel electrode 21, liquid crystal layer 22, and counter electrode 23 arranged in the reflective liquid crystal section 1A constitute a reflective liquid crystal display element 20 in a bistable liquid crystal display mode. A self-luminous display element 30 is arranged in the self-luminous element section 1B. In this manner, the display device 1 of this embodiment is a composite (hybrid) display device that combines the reflective liquid crystal display element 20 and the self-luminous display element 30, and can improve visibility outdoors under direct sunlight, as well as visibility indoors and at night.

[0039] 21, in the above-mentioned Patent Document 1, the reflective liquid crystal display element 20R arranged in the reflective liquid crystal section 1AR is active matrix driven, and in order to connect the reflective electrode 21R and the switching TFT 13R in the reflective liquid crystal section 1AR, the covering layer 35R is not provided in the reflective liquid crystal section 1AR, and it is necessary to arrange the covering layer 35R in an island shape only in the self-luminous element section 1BR where the self-luminous display element 30R is arranged. As a result, a boundary between the insulating film 105R and the covering layer 35R is generated for each pixel 1PR, and the self-luminous display element 30R may be deteriorated due to the intrusion of moisture or the like from the boundary.

[0040] On the other hand, in this embodiment, since the reflective liquid crystal display element 20 is in a bistable liquid crystal display mode, passive driving is possible regardless of the resolution, and active elements (also called switching elements) such as TFTs are not required. In the display device 1 of this embodiment, since it is not necessary to arrange TFTs in the reflective liquid crystal section 1A where the reflective liquid crystal display element 20 is arranged, there is no need to connect the pixel electrodes and TFTs in the reflective liquid crystal section as in Patent Document 1, and it is possible to provide the covering layer 35 continuously on the reflective liquid crystal section 1A and the self-luminous element section 1B. As a result, it is possible to prevent water and the like from entering from the boundary of the covering layer 35, and deterioration of the self-luminous display element 30 can be suppressed.

[0041] In this manner, in this embodiment, the bistable liquid crystal display mode is adopted as the display mode of the reflective liquid crystal display element 20, thereby enabling passive driving. As a result, it is no longer necessary to provide the covering layer 35 only on the self-luminous element section 1B where the self-luminous display element 30 is arranged for the purpose of contact between the pixel electrode and the TFT, and for example, the entire panel can be sealed in one go. This eliminates the boundary of the covering layer 35 within the panel surface, suppresses the intrusion of moisture, etc., and suppresses deterioration of the self-luminous display element 30. Hereinafter, this embodiment will be described in detail.

[0042] As shown in FIG. 2A, the display device 1 has a display area (active area) 10A capable of displaying an image, and a non-display area (non-active area) 10B surrounding the display area 10A and unable to display an image. The non-display area 10B includes a first non-display area portion 10B1 disposed on the display area 10A side, and a second non-display area portion 10B2 disposed outside the first non-display area portion 10B1. The first non-display area portion 10B1 has a black matrix layer 24X, and thus can realize a black frame. The second non-display area portion 10B2 does not have a black matrix layer.

[0043] 2B, the display device 1 includes, for example, row electrodes 21P arranged in the row direction and connected to row electrode signal wiring 21PL, and column electrodes 23P arranged in the column direction and connected to column electrode signal wiring 23PL. The row electrodes 21P and the row electrode signal wiring 21PL are connected in a region overlapping with the black matrix layer 24X in a planar view. The column electrodes 23P and the column electrode signal wiring 23PL are connected in a region overlapping with the black matrix layer 24X in a planar view. The row electrodes 21P correspond to the pixel electrodes 21, and the column electrodes 23P correspond to the counter electrodes 23. The row electrode signal wiring 21PL and the column electrode signal wiring 23PL correspond to wiring 330 described later.

[0044] The display device 1 has a plurality of pixels 1P arranged in a matrix in a display region 10A, and each of the plurality of pixels 1P includes a reflective liquid crystal section 1A and a self-luminous element section 1B. The reflective liquid crystal section 1A and the self-luminous element section 1B are arranged adjacent to each other in a planar view. A "pixel" is the smallest unit that constitutes a display image. The display device 1 may be, for example, a black and white display device or a color display device. In the case of a color display device, the pixel 1P may be a sub-pixel. Here, a "sub-pixel" refers to each region of a single color (usually a primary color) included in a pixel that constitutes a color display image.

[0045] The display device 1 further includes a flexible printed circuit (FPC) 10C provided in the non-display area 10B and electrically connected to the first substrate 100. The FPC 10C is a flexible printed circuit, and electrically connects the first substrate 100 to an external (host) control circuit board, which is a signal supply source.

[0046] 2A, the outer shape of the display device 1 may be polygonal, with the FPC 10C provided on one side thereof. Such a polygonal display device 1 can be used as a module for a smart watch.

[0047] As shown in FIG. 1, the display device 1 of this embodiment comprises, in order, a first substrate 100 having a current supply TFT 12 serving as a switching element, a liquid crystal layer 22 including liquid crystal molecules 22A, and a second substrate 200 having a counter electrode 23.

[0048] In the reflective liquid crystal section 1A, the first substrate 100 includes, in order toward the liquid crystal layer 22 side, a first support substrate 101, a gate insulating film 103, an inorganic insulating film 104, an insulating film 105, a reflector 21X, a covering layer 35, and a pixel electrode 21. In the self-light emitting element section 1B, the first substrate 100 includes, in order toward the liquid crystal layer 22 side, a first support substrate 101, a source electrode 12S, a semiconductor layer 102, a drain electrode 12D, a gate insulating film 103, a gate electrode 12G, an inorganic insulating film 104, an insulating film 105, a first electrode 31, a self-light emitting element side insulating film 32, an organic layer 33, a second electrode 34, and a covering layer 35.

[0049] The source electrode 12S, the gate electrode 12G, the drain electrode 12D, and the semiconductor layer 102 constitute a current supply TFT 12. The first electrode 31, the organic layer 33, and the second electrode 34 constitute a self-luminous display element 30. The self-luminous display element 30 is covered with a covering layer 35. The first electrode 31 is, for example, an anode, the organic layer 33 is, for example, an organic light-emitting diode (OLED) layer, and the second electrode 34 is, for example, a cathode. The self-luminous display element 30 is, for example, an organic electroluminescence (EL) display element.

[0050] The second substrate 200 includes, in this order toward the liquid crystal layer 22, a second support substrate 201, a color filter layer 24, and a counter electrode 23. A circular polarizer 25 is provided on the surface of the second substrate 200 opposite to the liquid crystal layer 22.

[0051] The reflector 21X, pixel electrode 21, liquid crystal layer 22, and counter electrode 23 arranged in the reflective liquid crystal section 1A constitute a reflective liquid crystal display element 20 of a bistable liquid crystal display mode. The bistable liquid crystal display element can be designed in the same manner as, for example, Japanese Patent Publications No. 4530217 and No. 4942898. The entirety of Japanese Patent No. 4530217 and Japanese Patent No. 4942898 are incorporated by reference into this embodiment.

[0052] In this embodiment, the reflective electrode 21R used in the above Patent Document 1 is separated into the pixel electrode 21 and the reflector 21X, so that it is possible to eliminate contact between the switching element of the reflective liquid crystal section and the pixel electrode. Furthermore, in this embodiment, the reflective electrode 21R is separated into the pixel electrode 21 and the reflector 21X, so that it is not necessary to separate the pixel electrodes 21 between adjacent pixels, and driving in a passive matrix can be realized.

[0053] FIG. 4 is a schematic cross-sectional view illustrating the connection between the counter electrode and the wiring in the non-display area of ​​the display device of the first embodiment. FIG. 5 is a schematic cross-sectional view illustrating the connection between the pixel electrode and the wiring in the non-display area of ​​the display device of the first embodiment. As shown in FIGS. 4 and 5, the first substrate 100 and the second substrate 200 are bonded at a certain interval by a seal 310 provided on the outer periphery (non-display area 10B), and liquid crystal molecules 22A are sealed in the gap to provide the liquid crystal layer 22. The seal 310 contains spherical spacers 320 whose surfaces are coated with gold. As shown in FIG. 4, the display device 1 has a non-display area 10B provided around the display area 10A and wiring 330 provided in the non-display area 10B of the first substrate 100, and the counter electrode 23 and the wiring 330 are connected in the non-display area 10B. Also, as shown in FIG. 5, the pixel electrode 21 and the wiring 330 are connected in the non-display area 10B. All of the connection parts are disposed outside the TFE (coating layer 35), and there is no need to provide contact holes in the TFE or various insulating layers for connection. The wiring 330 is connected to an external (host) control circuit board, which is a signal supply source, via the FPC 10C.

[0054] The liquid crystal layer 22 includes liquid crystal molecules 22A. It is difficult to provide the liquid crystal layer 22 only in the reflective liquid crystal section 1A, and the liquid crystal layer 22 is provided on the entire surface including the self-luminous element section 1B together with the counter electrode 23. When a voltage less than a threshold is applied between the pixel electrode 21 and the counter electrode 23, the liquid crystal layer 22 is in one of a first stable state and a second stable state in which the orientation state of the liquid crystal molecules 22A is different from each other, and the first stable state and the second stable state are switched by applying a pulse-wave voltage between the pixel electrode 21 and the counter electrode 23. When switching between the first stable state and the second stable state, a pulse-wave voltage is applied between the pixel electrode 21 and the counter electrode 23, but it is not necessary to continue applying the voltage to maintain the first stable state and the second stable state. The no-voltage state also includes a case where no voltage is applied between the pixel electrode 21 and the counter electrode 23.

[0055] The liquid crystal molecules 22A are liquid crystal molecules having a positive or negative dielectric anisotropy (Δε) defined by the following formula (L). Liquid crystal molecules having a positive dielectric anisotropy are also called positive liquid crystals, and liquid crystal molecules having a negative dielectric anisotropy are also called negative liquid crystals. The long axis direction of the liquid crystal molecules is the direction of the slow axis. The liquid crystal molecules 22A of this embodiment are preferably positive liquid crystals. Δε = (dielectric constant in the long axis direction of the liquid crystal molecules) - (dielectric constant in the short axis direction of the liquid crystal molecules) (L)

[0056] The display device 1 includes a vertical alignment film 41 disposed between the first substrate 100 and the liquid crystal layer 22, and a grating layer 42 disposed between the second substrate 200 and the liquid crystal layer 22. When a voltage less than a threshold is applied between the pixel electrode 21 and the counter electrode 23, the liquid crystal layer 22 is in one of a first stable state in which the liquid crystal molecules 22A are vertically aligned and a second stable state in which the liquid crystal molecules 22A are HAN (Hybrid Aligned Nematic) aligned, and the first stable state and the second stable state are switched by applying a voltage of a pulse waveform between the pixel electrode 21 and the counter electrode 23. The alignment of the liquid crystal molecules 22A in the first stable state is also called an initial alignment. That is, the initial alignment of the liquid crystal molecules 22A in this embodiment is vertical alignment. In this embodiment, the circular polarizer 25 is set so that the display device 1 displays black in the first stable state (vertical alignment). In this embodiment, the display device 1 displays white in the second stable state (HAN alignment).

[0057] The switching from the first stable state to the second stable state is realized by applying a predetermined pulse voltage (voltage having a first pulse waveform) between the pixel electrode 21 and the counter electrode 23, which changes the alignment of the liquid crystal molecules 22A on the grating layer 42 side to the HAN alignment. The switching from the second stable state to the first stable state is realized by applying a predetermined pulse voltage (voltage having a second pulse waveform) between the pixel electrode 21 and the counter electrode 23, which changes the alignment of the liquid crystal molecules 22A on the grating layer 42 side to the vertical alignment. Voltage application is required only when switching the alignment, and voltage retention is not required. This bistable liquid crystal display mode is also called "ZBD (Zenithal Bistable Display)". It will be explained in more detail below.

[0058] Fig. 6 is a cross-sectional view illustrating a case where the liquid crystal molecules of the display device of the embodiment 1 have a homeotropic alignment. Fig. 7 is a diagram showing a first pulse waveform of a voltage applied between a pixel electrode and a counter electrode of the display device of the embodiment 1. Fig. 8 is a cross-sectional view illustrating a case where the liquid crystal molecules of the display device of the embodiment 1 have a HAN alignment. Fig. 9 is a diagram showing a second pulse waveform of a voltage applied between a pixel electrode and a counter electrode of the display device of the embodiment 1. Fig. 6 shows an initial alignment state, i.e., a first stable state. Fig. 8 shows a second stable state.

[0059] In the first stable state, the liquid crystal molecules 22A are homeotropically aligned (vertically aligned) between the vertical alignment film 41 arranged on the first substrate 100 side and the grating layer 42 arranged on the second substrate 200 side, as shown in Fig. 6. At this time, when a voltage having a pulse waveform shown in Fig. 7 is applied between the pixel electrode 21 on the first substrate 100 side and the counter electrode 23 on the second substrate 200 side, the anchoring of the liquid crystal molecules 22A on the grating layer 42 side is released, and the liquid crystal molecules 22A rotate within the plane of the drawing (Fig. 6). The rotated liquid crystal molecules 22A are realigned to the second stable state, and assume the HAN alignment shown in Fig. 8.

[0060] When a voltage having a pulse waveform shown in Fig. 9 is applied between the pixel electrode 21 and the counter electrode 23 in the HAN orientation state shown in Fig. 8, the anchoring of the liquid crystal molecules 22A on the grating layer 42 side is released, and the liquid crystal molecules 22A rotate within the plane of the drawing (Fig. 8). The rotated liquid crystal molecules 22A are reoriented to the first stable state, and assume the homeotropic orientation shown in Fig. 6.

[0061] In order to switch between the first stable state shown in FIG. 6 and the second stable state shown in FIG. 8, it is necessary to apply a voltage having a pulse waveform. However, since the first stable state and the second stable state are each energetically stable states, it is not necessary to continue to apply a voltage between the pixel electrode 21 and the counter electrode 23 in order to maintain each stable state.

[0062] The vertical alignment film 41 is provided on the entire display area 10A. The vertical alignment film has a function of aligning the liquid crystal molecules in the liquid crystal layer in a direction perpendicular to the surface of the vertical alignment film when the voltage applied to the liquid crystal layer is less than a threshold voltage (also referred to as when no voltage is applied). Here, the liquid crystal molecules being aligned in a direction perpendicular to the surface of the vertical alignment film means that the pretilt angle of the liquid crystal molecules is 85° or more and 90° or less with respect to the surface of the vertical alignment film. The pretilt angle of the liquid crystal molecules means the angle at which the major axis of the liquid crystal molecules is inclined with respect to the main surface of each substrate when no voltage is applied to the liquid crystal layer. The magnitude of the pretilt depends particularly on the combination of the alignment film or grating layer and the liquid crystal molecules.

[0063] The material of the vertical alignment film 41 may be a material commonly used in the field of liquid crystal display panels, such as a polymer having polyimide in the main chain, a polymer having polyamic acid in the main chain, a polymer having polysiloxane in the main chain, etc. The alignment film may be formed by applying an alignment film material, and the application method is not particularly limited, and for example, flexographic printing, inkjet application, etc. may be used.

[0064] The grating layer 42 is provided on the entire surface of the display region 10A. The grating layer 42 is, for example, a layer having grooves with triangular cross sections on the surface facing the liquid crystal layer 22. The grating layer is, for example, made of an insulating film. The grating layer 42 is preferably transparent.

[0065] By optimizing the depth and interval (pitch) of the grooves, when the voltage applied to the liquid crystal layer 22 is less than the threshold voltage, two stable alignment states are obtained: a state in which the liquid crystal molecules 22A are vertically aligned on the second substrate 200 side (FIG. 6), and a state in which the liquid crystal molecules 22A are horizontally aligned on the second substrate 200 side (FIG. 8). Furthermore, by applying voltage pulses of different polarities between the pixel electrode 21 and the counter electrode 23, it is possible to switch between the alignment state shown in FIG. 6 and the alignment state shown in FIG. 8. Even when no voltage pulse is applied, the two alignment states are maintained (held).

[0066] In the first stable state, it is preferable that the pretilt angle of the liquid crystal molecules 22A on the first substrate 100 side is 85° or more and 90° or less, and the pretilt angle of the liquid crystal molecules 22A on the second substrate 200 side is 85° or more and 90° or less. By adopting such an embodiment, a better black display can be realized.

[0067] In the second stable state, it is preferable that the pretilt angle of the liquid crystal molecules 22A on the first substrate 100 side is 85° or more and 90° or less, and the pretilt angle of the liquid crystal molecules 22A on the second substrate 200 side is 0° or more and 5° or less. By adopting such an embodiment, a better white display can be realized.

[0068] The first support substrate 101 may be, for example, an insulating substrate made of a glass substrate or a resin film such as polyimide. The second support substrate 201 facing the viewer may be, for example, an insulating substrate made of glass or a transparent (light-transmitting) film.

[0069] The semiconductor layer 102 is provided in the self-luminous element portion 1B, but not in the reflective liquid crystal portion 1A. Here, "a certain member is provided in a certain region" means that the certain member is provided in at least a part of the certain region in a plan view. Also, "a certain member is not provided in a certain region" means that the certain member is not provided at all in the certain region in a plan view.

[0070] The semiconductor layer 102 may be made of a semiconductor that is commonly used in display devices, such as low-temperature polycrystalline silicon (hereinafter referred to as LTPS) or indium gallium zinc oxide (hereinafter referred to as In-Ga-Zn-O).

[0071] The source electrode 12S, the drain electrode 12D, and the gate electrode 12G are provided in the self-luminous element section 1B, and are not provided in the reflective liquid crystal section 1A. The source electrode 12S, the drain electrode 12D, and the gate electrode 12G may be made of a metal such as titanium, aluminum, molybdenum, copper, or chromium, or a conductive layer containing an alloy thereof.

[0072] The gate insulating film 103 is provided over the entire surface of the display region 10A. Here, "a certain member is provided over the entire surface of a certain region" means that the certain member is provided over almost the entire surface of the certain region in a plan view, excluding specific portions such as contact holes. The gate insulating film 103 is preferably an inorganic insulating film. Examples of inorganic insulating films include silicon oxide (SiO x ) film, silicon nitride (Si x N y ) film, silicon oxynitride (SiO x N y ;x>y) film, silicon oxynitride (SiN x O y ;x>y) films or laminated films thereof can be used.

[0073] The inorganic insulating film 104 is provided over the entire surface of the display region 10A. The inorganic insulating film 104 may be, for example, silicon oxide (SiO x ) film, silicon nitride (Si x N y ) film, silicon oxynitride (SiO x N y ;x>y) film, silicon oxynitride (SiN x O y ;x>y) films or laminated films thereof can be used.

[0074] The insulating film 105 is provided over the entire display area 10A. The insulating film 105 may be an inorganic insulating film, an organic insulating film, or a laminate of an inorganic insulating film and an organic insulating film. The inorganic insulating film may be, for example, silicon oxide (SiO x ) film, silicon nitride (Si x N y ) film, silicon oxynitride (SiO x N y ;x>y) film, silicon oxynitride (SiN x O y As the organic insulating film, for example, an organic film such as an acrylic resin, a polyimide resin, or a novolac resin, or a laminate thereof can be used.

[0075] TFTs such as a driving TFT 11 and a current supply TFT 12, and wiring such as a bus line are provided on one surface of the first support substrate 101, and the insulating film 105 has a function of flattening the surface, and is therefore also called a flattening film. The insulating film 105 is disposed for the purpose of flattening the surface by eliminating unevenness between the portions where the TFTs and the like are provided and the portions where they are not provided, and is therefore preferably formed of an organic material such as a polyimide resin.

[0076] The reflector 21X is provided in the reflective liquid crystal section 1A, but not in the self-luminous element section 1B. The reflector 21X is provided between the insulating film 105 and the covering layer 35. The reflector 21X has a function of reflecting light that is incident from the second substrate 200 side and passes through the liquid crystal layer 22, toward the second substrate 200 side. The incident light from the second substrate 200 side is reflected by the reflector 21X, and the reflected light passes through the liquid crystal layer 22, thereby performing a reflective display. The reflector 21X can be obtained by forming a film of various highly reflective metals such as Al and Ag alloys.

[0077] The reflector 21X is preferably disposed in the same layer as the first electrode 31. The display device 1 in this embodiment can be manufactured more easily because the reflector 21X and the first electrode 31 can be formed simultaneously.

[0078] The pixel electrode 21 and the counter electrode 23 are provided on the entire surface of the display region 10 A. The pixel electrode 21 and the counter electrode 23 can be formed by forming a single layer or multiple layers of a transparent conductive material such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), tin oxide (SnO), or an alloy thereof by a sputtering method or the like, and then patterning the layer using a photolithography method.

[0079] The pixel electrodes 21 and the counter electrodes 23 are connected to terminal sections provided in the non-display area 10B, and the voltage between the pixel electrodes 21 and the counter electrodes 23 is controlled via the terminal sections, thereby achieving passive driving of the reflective liquid crystal display element 20. In this manner, since the reflective liquid crystal display element 20 is passively driven, active elements (diodes, transistors, etc.) are not required. Since signals are input from terminal sections provided on the end face (non-display area 10B) of the display device 1, the pixel electrodes 21 and the counter electrodes 23, which are transparent electrodes, are arranged in the display area 10A, but wiring such as gate bus lines and source bus lines for controlling the voltage between the pixel electrodes 21 and the counter electrodes 23 is not arranged.

[0080] The color filter layer 24 is disposed between the second support substrate 201 and the counter electrode 23. The color filter layer 24 is, for example, a red color filter, a green color filter, or a blue color filter. The red color filter, the green color filter, and the blue color filter are, for example, made of a transparent resin containing a pigment.

[0081] By providing the color filter layer 24, it is possible to realize a color display in the reflective liquid crystal display element 20. On the other hand, a color display can also be realized by using the color filter layer 24 on the self-luminous display element 30 side, but when the material of the organic layer 33 is selected so that, for example, red, green, and blue light is directly emitted, the color filter layer 24 on the self-luminous display element 30 side becomes unnecessary.

[0082] The circular polarizer 25 is a polarizer that converts incident unpolarized light into circularly polarized light. The circular polarizer 25 is composed of, for example, a linear polarizer and a λ / 4 retardation plate. In addition, a ½ wavelength plate may be used in combination to provide a ¼ wavelength condition for a wide range of wavelengths. The λ / 4 retardation plate is composed of a uniaxially stretched optical film.

[0083] The reflective liquid crystal display element 20 has a circular polarizer 25. By adopting such an embodiment, the following effects can be realized. The phase of the linearly polarized light passing through the circular polarizer 25 is shifted by 1 / 4 wavelength, and the light becomes, for example, right-handed polarized light. Since the initial orientation of the liquid crystal molecules 22A is vertical, the external light passes through the liquid crystal layer 22 as it is, and is reflected by the reflector 21X, whereby the polarization is reversed from right-handed circularly polarized light to left-handed circularly polarized light. Therefore, the external light that travels in the reverse direction and returns to the circular polarizer 25 becomes linearly polarized light that is perpendicular to the transmission axis of the linear polarizer by 90°, and cannot pass through the circular polarizer 25, thereby realizing a black display.

[0084] On the other hand, when a voltage having a first pulse waveform is applied between the pixel electrode 21 and the counter electrode 23 and the liquid crystal molecules 22A assume the HAN orientation, the external light is further shifted in phase by a quarter wavelength in the liquid crystal layer 22, and therefore has a phase difference of a half wavelength when it reaches the reflector 21X, and is reflected as linearly polarized light. After being reflected, the external light travels a path opposite to that of incidence, and therefore passes through the circular polarizer 25, thereby achieving a white display.

[0085] Furthermore, when a voltage having a second pulse waveform different from the first pulse waveform is applied between the pixel electrode 21 and the counter electrode 23, and the liquid crystal molecules 22A are vertically aligned, black display can be achieved as described above.

[0086] The self-luminous display element 30 is provided in the self-luminous element section 1B of one pixel 1P, and includes a first electrode 31 provided on the liquid crystal layer 22 side of the insulating film 105, a self-luminous element side insulating film 32 provided around the first electrode 31, an organic layer 33 provided on the liquid crystal layer 22 side of the first electrode 31 surrounded by the self-luminous element side insulating film 32, and a second electrode 34 covering the entire self-luminous element side insulating film 32 and the organic layer 33 (covering the entire surface of the self-luminous element side insulating film 32 and the organic layer 33 on the liquid crystal layer 22 side).

[0087] The first electrode 31 is formed as, for example, an anode electrode. In the present embodiment, since the display screen is viewed from the upper side of FIG. 1, the first electrode 31 is formed as a reflective electrode, and is structured to radiate all emitted light upward. For this reason, a light-reflective material is selected based on the relationship of the work function with the organic layer 33 in contact with the first electrode 31. For example, it is formed of a laminated film of ITO / APC / ITO.

[0088] The self-luminous element-side insulating film 32, which is also called an insulating bank or a partition wall, defines the light-emitting region of the self-luminous display element 30 and is formed to prevent the first electrode 31 and the second electrode 34 from contacting each other and becoming conductive. An organic layer 33 is laminated on the first electrode 31 surrounded by the self-luminous element-side insulating film 32. The self-luminous element-side insulating film 32 is formed of a resin such as polyimide or acrylic resin.

[0089] The organic layer 33 is laminated on the liquid crystal layer 22 side of the first electrode 31 that is exposed by being surrounded by the self-luminous element-side insulating film 32. Although this organic layer 33 is shown as a single layer in Fig. 1, it is actually composed of multiple layers in which various materials are laminated. In addition, this organic layer 33 is vulnerable to moisture and cannot be patterned after being formed over the entire surface, so it is formed by selectively depositing evaporated or sublimated organic material only on necessary portions using a deposition mask.

[0090] Specifically, the organic layer 33 has a hole injection layer made of a material with good ionization energy matching that improves the injection of holes, for example, as a layer in contact with the first electrode (anode electrode) 31. The organic layer 33 has a hole transport layer on the liquid crystal layer 22 side of the hole injection layer that improves stable transport of holes and can confine electrons (energy barrier) in the light-emitting layer, and the hole transport layer is made of, for example, an amine-based material. Furthermore, the organic layer 33 has a light-emitting layer selected according to the emission wavelength on the liquid crystal layer 22 side of the hole transport layer. For example, the light-emitting layer is formed by doping Alq3 with a red or green organic fluorescent material for red or green for red and green. Also, a DSA-based organic material is used as a blue-based material. On the other hand, when colored by the color filter layer 24, all the light-emitting layers can be formed of the same material without doping. The organic layer 33 further has an electron transport layer on the liquid crystal layer 22 side of the light-emitting layer that improves the injection of electrons and transports electrons stably. The electron transport layer is made of Alq3 or the like. Each of these layers is laminated to a thickness of about several tens of nm to form a laminated film of the organic layer 33. Note that an electron injection layer such as LiF or Liq that improves the injection of electrons may be provided between the organic layer 33 and the second electrode 34. In this embodiment, the organic layer 33 may include each of these organic layers and inorganic layers.

[0091] As described above, the light-emitting layer of the laminated film of the organic layer 33 may be formed by depositing organic layers of materials corresponding to each color of RGB. In the example shown in FIG. 1, the light-emitting layer is formed of the same organic material, and the emitted color is specified by the color filter layer 24. In addition, if the light-emitting performance is important, it is preferable that the hole transport layer, the electron transport layer, and the like are separately deposited with materials suitable for the light-emitting layer. However, in consideration of material costs, the same material may be laminated in common for two or three colors of RGB.

[0092] After the laminated film of all the organic layers 33 including the electron injection layer such as a LiF layer is formed, the second electrode 34 is formed on the liquid crystal layer 22 side of the self-luminous element side insulating film 32 and the organic layers 33. The second electrode 34 needs to be completely covered with the covering layer 35. This is because the second electrode 34 is made of a light-transmitting material, for example, a thin Mg-Ag eutectic film, and is easily corroded by moisture.

[0093] As a result, the self-luminous display element 30 is formed in the self-luminous element section 1B. As shown in FIG. 1, the liquid crystal layer 22 and the counter electrode 23 are also provided on the self-luminous display element 30. As described above, it is difficult to provide the liquid crystal layer 22 only in the reflective liquid crystal section 1A. However, the pixel electrode 21 is not arranged in the self-luminous element section 1B. Therefore, in the self-luminous element section 1B, the state is the same as when the voltage applied between the pixel electrode 21 and the counter electrode 23 is less than the threshold value. That is, although it becomes normally black with respect to the outside light, the light emitted by the self-luminous display element 30 passes through the circular polarizer 25 without any change because the liquid crystal layer 22 is vertically oriented, which is the same as when the liquid crystal layer 22 is not present. And, the light that passes through the circular polarizer 25 is viewed as it is, so the image displayed by the light emitted by the self-luminous display element 30 is viewed as it is from the observation surface side.

[0094] The light emitted by the self-luminous display element 30 is attenuated by about half by the circular polarizer 25 when it passes through the circular polarizer. However, it is preferable that the circular polarizer 25 is also disposed in the self-luminous element section 1B. The reason is as follows. That is, when external light enters from the front, the first electrode 31 of the self-luminous display element 30 is formed of a light-reflective material as described above, and if the light incident from the front is reflected by the first electrode 31 in the self-luminous display element 30 and goes out, the display screen becomes very difficult to see. However, if the circular polarizer 25 is present, the direction of rotation of the circularly polarized light is reversed when the light is reflected by the first electrode 31 as described above, and the reflected light cannot pass through the circular polarizer. As a result, the reflected light can be cut off. When there is a lot of external light, the self-luminous display element 30 is not operated. However, even when the reflective liquid crystal display element 20 is operating, reflected light is generated regardless of whether the self-luminous display element 30 is operating or not. Therefore, even when the reflective liquid crystal display element 20 is operating, if the circular polarizer 25 is not present in the self-luminous element section 1B, the visibility characteristics of the display device 1 will be significantly reduced.

[0095] The covering layer 35 is also called a sealing layer or a thin film encapsulation agent (TFE). The covering layer 35 is preferably an inorganic insulating film. Examples of the covering layer 35 include an inorganic insulating film such as a silicon nitride film or a silicon oxide film. The covering layer 35 may be a single layer or a laminated film of two or more layers.

[0096] The covering layer 35 is provided continuously on the reflective liquid crystal section 1A and the self-luminous element section 1B. By adopting such an embodiment, it is possible to suppress deterioration of the self-luminous display element 30. Here, a certain member being provided continuously on two regions means that a certain member is provided on the entire surfaces of the two regions, and is arranged without interruption from one of the two regions to the other region in a planar view. The covering layer 35 is provided on the entire surfaces of the reflective liquid crystal section 1A and the self-luminous element section 1B, and is arranged without interruption from the reflective liquid crystal section 1A to the self-luminous element section 1B in a planar view.

[0097] The covering layer 35 is preferably provided continuously on the plurality of pixels 1P. By adopting such an embodiment, it is possible to further prevent water and the like from entering through the boundaries of the covering layer 35, and therefore to further prevent deterioration of the self-luminous display element 30. The covering layer 35 is provided on the entire surface of the plurality of pixels 1P, and is disposed seamlessly between the plurality of pixels 1P in a plan view.

[0098] The circuit for driving the self-luminous display element 30 is configured as shown in the equivalent circuit diagram in FIG. 3, for example. That is, the gate electrode of the driving TFT 11 is connected to the gate bus line 15, and a gate signal (selection signal) is applied to the gate bus line 15 to select a row of pixels arranged horizontally. The source electrode of the driving TFT 11 is connected to the source bus line 14 to allow a data signal to be input to a row of pixels arranged vertically. Then, only pixels at the intersection of the gate bus line 15 to which the selection signal is applied and the source bus line 14 to which the data signal is applied can display based on the applied data signal. The drain electrode of the driving TFT 11 is connected to the gate electrode 12G of the current supply TFT 12, and the current flowing through the self-luminous display element 30 is controlled in accordance with the display information. The drain electrode 12D of the current supply TFT 12 is connected to the current bus line 16, and the source electrode 12S is connected to the first electrode 31 (anode electrode) of the self-luminous display element 30. The second electrode 34 (cathode electrode) of the self-luminous display element 30 is connected to the cathode bus line 17 via contact holes 17c1 and 17c2. By adopting such an embodiment, the self-luminous display element 30 provided in the self-luminous element section 1B can be driven.

[0099] When the driving TFT 11 is on, the voltages of the pixel electrode 21 and the counter electrode 23 are controlled so that a voltage less than the threshold value is applied between the pixel electrode 21 and the counter electrode 23, and the driving TFT 11 turns on the current supply TFT 12, thereby displaying an image by the self-luminous display element 30. On the other hand, when the driving TFT 11 is off, a voltage equal to or greater than the threshold value is applied between the pixel electrode 21 and the counter electrode 23, and the driving TFT 11 turns off the current supply TFT 12, thereby preventing the self-luminous display element 30 from displaying an image. By turning on and off the image display by the reflective liquid crystal display element 20 in synchronization with the on / off of the image display by the self-luminous display element 30, an image can be displayed appropriately.

[0100] (Embodiment 2) In this embodiment, the features unique to this embodiment will be mainly described, and the description of the contents overlapping with the above-mentioned embodiment 1 will be omitted. This embodiment is substantially the same as embodiment 1, except that the configuration of the alignment film disposed between the first substrate 100 and the liquid crystal layer 22 is different.

[0101] FIG. 10 is a cross-sectional view of a pixel included in the display device of the second embodiment. FIG. 11 is a cross-sectional view illustrating a case where the liquid crystal molecules included in the display device of the second embodiment have a TN orientation. FIG. 12 is a view showing a first pulse waveform of a voltage applied between a pixel electrode and a counter electrode included in the display device of the second embodiment. FIG. 13 is a cross-sectional view illustrating a case where the liquid crystal molecules included in the display device of the second embodiment have a HAN orientation. FIG. 14 is a view showing a second pulse waveform of a voltage applied between a pixel electrode and a counter electrode included in the display device of the second embodiment. FIG. 11 shows an initial orientation state, that is, a first stable state. FIG. 13 shows a second stable state.

[0102] The display device 1 of this embodiment includes a horizontal alignment film 43 having a pretilt arranged between the first substrate 100 and the liquid crystal layer 22, and a grating layer 42 arranged between the second substrate 200 and the liquid crystal layer 22. When a voltage less than a threshold is applied between the pixel electrode 21 and the counter electrode 23, the liquid crystal layer 22 is in one of a first stable state in which the liquid crystal molecules 22A are in a TN (Twisted Nematic) orientation and a second stable state in which the liquid crystal molecules 22A are in a HAN orientation. The first stable state and the second stable state are switched by applying a voltage of a pulse waveform between the pixel electrode 21 and the counter electrode 23. The initial orientation of the liquid crystal molecules 22A of this embodiment is the TN orientation. In this embodiment, the circular polarizer 25 is set so that the display device 1 displays black in the first stable state (TN orientation). In this embodiment, the display device 1 displays white in the second stable state (HAN orientation). Such a bistable liquid crystal display mode is also called ZBD.

[0103] The horizontal alignment film 43 having a pretilt is provided on the entire surface of the display region 10A. The horizontal alignment film 43 having a pretilt has a function of orienting the liquid crystal molecules 22A in the liquid crystal layer 22 at an angle exceeding 0° and not more than 10° with respect to the surface of the horizontal alignment film 43 when no voltage is applied. It is preferable that the horizontal alignment film 43 having a pretilt has a function of orienting the liquid crystal molecules 22A in the liquid crystal layer 22 at an angle of 3° or more and not more than 5° with respect to the surface of the horizontal alignment film 43 when no voltage is applied. By adopting such an embodiment, the initial alignment can be made TN alignment.

[0104] The material of the horizontal alignment film 43 having a pretilt may be a material commonly used in the field of liquid crystal display panels, such as a polymer having polyimide in its main chain, a polymer having polyamic acid in its main chain, or a polymer having polysiloxane in its main chain.

[0105] The horizontal alignment film 43 having a pretilt can be obtained, for example, by forming an alignment film material containing a polymer for rubbing alignment film on a substrate, and rubbing the surface of the film containing the polymer for rubbing alignment film in a predetermined direction (rubbing method) by rotating a roller wrapped with a cloth made of rayon, cotton, or the like while keeping the rotation speed and the distance between the roller and the substrate constant. The horizontal alignment film 43 having a pretilt can be obtained, for example, by subjecting the film surface of the alignment film to a rubbing treatment. The rubbing treatment can be performed from the back to the front of the drawing (FIG. 10).

[0106] In the first stable state, the liquid crystal molecules 22A are TN-oriented between the horizontal alignment film 43 having a pretilt arranged on the first substrate 100 side and the grating layer 42 arranged on the second substrate 200 side, as shown in Fig. 11. When a voltage having a pulse waveform shown in Fig. 12 is applied between the pixel electrode 21 on the first substrate 100 side and the counter electrode 23 on the second substrate 200 side, the anchoring of the liquid crystal molecules 22A on the grating layer 42 side is released, and the liquid crystal molecules 22A rotate. The rotated liquid crystal molecules 22A are reoriented to the second stable state, and assume the HAN orientation shown in Fig. 13.

[0107] When a voltage having a pulse waveform as shown in Fig. 14 is applied between the pixel electrode 21 and the counter electrode 23 in the HAN orientation state as shown in Fig. 13, the anchoring of the liquid crystal molecules 22A on the grating layer 42 side is released, and the liquid crystal molecules 22A rotate. The rotated liquid crystal molecules 22A are reoriented to the first stable state, and assume the TN orientation as shown in Fig. 11.

[0108] In order to switch between the first stable state shown in FIG. 11 and the second stable state shown in FIG. 13, it is necessary to apply a voltage having a pulse waveform. However, since the first stable state and the second stable state are each energetically stable states, it is not necessary to continue to apply a voltage between the pixel electrode 21 and the counter electrode 23 in order to maintain each stable state.

[0109] In the first stable state, it is preferable that the pretilt angle of the liquid crystal molecules 22A on the first substrate 100 side is 3° or more and 5° or less, the pretilt angle of the liquid crystal molecules 22A on the second substrate 200 side is 0° or more and 5° or less, and the angle between the alignment direction of the liquid crystal molecules 22A on the first substrate 100 side and the alignment direction of the liquid crystal molecules 22A on the second substrate 200 side is 80° or more and 90° or less in plan view. By adopting such an embodiment, better black display can be realized.

[0110] In the second stable state, it is preferable that the pretilt angle of the liquid crystal molecules 22A on the first substrate 100 side is 3° or more and 5° or less, and the pretilt angle of the liquid crystal molecules 22A on the second substrate 200 side is 85° or more and 90° or less. By adopting such an embodiment, a better white display can be realized.

[0111] (Embodiment 3) In this embodiment, the characteristics unique to this embodiment will be mainly described, and the description of the contents overlapping with the above-mentioned embodiment 1 will be omitted. This embodiment is substantially the same as embodiment 1, except that the configuration of the alignment film disposed between the first substrate 100 and the liquid crystal layer 22 is different, an alignment film is provided between the second substrate 200 and the liquid crystal layer 22 instead of the grating layer, and a linear polarizer is used instead of the circular polarizer 25.

[0112] FIG. 15 is a cross-sectional view of a pixel included in the display device of the third embodiment. FIG. 16 is a cross-sectional view illustrating a case where the liquid crystal molecules included in the display device of the third embodiment are aligned in a homogeneous manner. FIG. 17 is a view showing a first pulse waveform of a voltage applied between a pixel electrode and a counter electrode included in the display device of the third embodiment. FIG. 18 is a cross-sectional view illustrating a case where the liquid crystal molecules included in the display device of the third embodiment are aligned in a twisted manner. FIG. 19 is a view showing a second pulse waveform of a voltage applied between a pixel electrode and a counter electrode included in the display device of the third embodiment. FIG. 16 shows an initial alignment state, that is, a first stable state. FIG. 18 shows a second stable state.

[0113] As shown in FIG. 15, the display device 1 of this embodiment includes a weak anchoring alignment film 44 disposed between the first substrate 100 and the liquid crystal layer 22, and a strong anchoring alignment film 45 disposed between the second substrate 200 and the liquid crystal layer 22. When a voltage less than a threshold is applied between the pixel electrode 21 and the counter electrode 23, the liquid crystal layer 22 is in one of a first stable state in which the liquid crystal molecules 22A are homogeneously aligned, and a second stable state in which the liquid crystal molecules 22A on the first substrate 100 side are in a twisted alignment rotated 180° from the first stable state in a planar view. The first stable state and the second stable state are switched by applying a pulse waveform voltage between the pixel electrode 21 and the counter electrode 23. The initial alignment of the liquid crystal molecules 22A of this embodiment is homogeneous alignment. In this embodiment, the circular polarizer 25 is set so that the display device 1 displays black in the first stable state (homogeneous alignment). In this embodiment, the display device 1 displays white in the second stable state (twisted alignment). This type of bistable liquid crystal display mode is called BiNem.

[0114] The cell gap of the liquid crystal layer 22 can be set to, for example, 2 μm.

[0115] The weak anchoring alignment film 44 and the strong anchoring alignment film 45 are provided on the entire surface of the display area 10A. The weak anchoring alignment film 44 and the strong anchoring alignment film 45 are, for example, rubbing alignment films, and the anchoring strength can be set to a desired range by changing the rubbing strength. The weak anchoring alignment film 44 is an alignment film with a lower anchoring energy than the strong anchoring alignment film 45.

[0116] In the first stable state, the liquid crystal molecules 22A are homogeneously aligned between the weak anchoring alignment film 44 arranged on the first substrate 100 side and the strong anchoring alignment film 45 arranged on the second substrate 200 side as shown in FIG. 16. At this time, when a voltage having a pulse waveform shown in FIG. 17 is applied between the pixel electrode 21 on the first substrate 100 side and the counter electrode 23 on the second substrate 200 side, the anchoring of the liquid crystal molecules 22A on the first substrate 100 side is released, and the liquid crystal molecules 22A rotate 180° in a plan view from the first stable state. On the other hand, the alignment direction of the liquid crystal molecules 22A on the second substrate 200 side does not change. The rotation of the liquid crystal molecules 22A on the first substrate 100 side propagates toward the second substrate 200 side to rotate the liquid crystal molecules 22A. The rotated liquid crystal molecules 22A are realigned to the second stable state and take the twisted alignment shown in FIG. 18.

[0117] When a voltage having a pulse waveform as shown in Fig. 19 is applied between the pixel electrode 21 and the counter electrode 23 in the twisted alignment state shown in Fig. 18, the anchoring of the liquid crystal molecules 22A on the first substrate 100 side is released, and the liquid crystal molecules 22A rotate. The rotated liquid crystal molecules 22A are realigned to the first stable state, and assume the homogeneous alignment as shown in Fig. 16.

[0118] In order to switch between the first stable state shown in FIG. 16 and the second stable state shown in FIG. 18, it is necessary to apply a voltage having a pulse waveform. However, since the first stable state and the second stable state are each energetically stable states, it is not necessary to continue to apply a voltage between the pixel electrode 21 and the counter electrode 23 in order to maintain each stable state.

[0119] In the first stable state, it is preferable that the pretilt angle of the liquid crystal molecules 22A on the first substrate 100 side is 0° or more and 5° or less, the pretilt angle of the liquid crystal molecules 22A on the second substrate 200 side is 5° or more and 10° or less, and the angle between the alignment direction of the liquid crystal molecules 22A on the first substrate 100 side and the alignment direction of the liquid crystal molecules 22A on the second substrate 200 side is 0° or more and 10° or less in a plan view. By adopting such an embodiment, better black display can be realized.

[0120] In the second stable state, it is preferable that the pretilt angle of the liquid crystal molecules 22A on the first substrate 100 side is 0° or more and 5° or less, the pretilt angle of the liquid crystal molecules 22A on the second substrate 200 side is 5° or more and 10° or less, the angle between the alignment direction of the liquid crystal molecules 22A on the first substrate 100 side and the alignment direction of the liquid crystal molecules 22A on the second substrate 200 side is 0° or more and 10° or less in plan view, and the liquid crystal molecules 22A are aligned with an in-plane twist of 170° or more and 180° or less from the first substrate 100 side to the second substrate 200 side. By adopting such an embodiment, a better white display can be realized.

[0121] (Embodiment 4) In this embodiment, features unique to this embodiment will be mainly described, and descriptions of contents overlapping with the above-mentioned embodiment 1 will be omitted. This embodiment is substantially the same as embodiment 1, except that the configuration of the reflector 21X is different.

[0122] Fig. 20 is a cross-sectional schematic diagram of a pixel included in the display device of embodiment 4. As shown in Fig. 20, the reflector 21X included in the display device 1 of this embodiment has an uneven shape on the surface facing the liquid crystal layer 22. With this configuration, the reflected light is diffused in all directions, thereby improving visibility and reflection characteristics.

[0123] The reflector 21X has a micro-reflective structure (MRS). The reflector 21X having the MRS shape can be obtained, for example, by forming a concave-convex shape on the surface of the insulating film 105 on the liquid crystal layer 22 side by photolithography, and depositing various highly reflective metals such as Al and Ag alloys. The MRS shape can scatter external light within a certain angle range. Therefore, it is possible to efficiently utilize the surrounding light, and a bright reflective display can be obtained. [Explanation of symbols]

[0124] 1, 1R: Display device 1A, 1AR: Reflective LCD section 1B, 1BR: Light-emitting element section 1P, 1PR: Pixel 10A:Display area 10B: Hidden area 10B1: First non-display area 10B2: Second non-display area 10C: Flexible Printed Circuit Board (FPC) 11CHR: Contact hole 11: Driving TFT 12, 12R: TFT for current supply 12D, 12DR, 13DR: Drain electrodes 12G, 12GR, 13GR: Gate electrode 12S, 12SR, 13SR: Source electrodes 13R: TFT for switch 14: Source bus line 15: Gate Bus Line 16: Current bus line 17: Cathode bus line 17c1, 17c2: Contact holes 20, 20R: Reflective liquid crystal display element 21: Pixel electrode 21P: Row electrode 21PL: Row electrode signal wiring 21R:Reflecting electrode 21X:Reflector 22, 22R: Liquid crystal layer 22A, 22AR: Liquid crystal molecules 23, 23R: Counter electrode 23P: Column electrode 23PL: Column electrode signal wiring 24, 24R: Color filter layer 24X: Black matrix layer 25, 25R: Circular polarizing plate 30, 30R: Self-luminous display element 31, 31R: first electrode 32, 32R: Self-emitting element side insulating film 32aR: Liquid crystal element side insulating film 33, 33R: Organic layer 34, 34R: second electrode 35, 35R: Covering layer 41: Vertical alignment film 42: Grating layer 43: Horizontal alignment film with pretilt 44: Weak anchoring alignment film 45: Strong anchoring alignment film 100, 100R: first board 101, 101R: first support substrate 102, 102AR, 102BR: Semiconductor layer 103, 103R: Gate insulating film 104, 104R: inorganic insulating film 105, 105R: insulating film 200, 200R: Second board 201, 201R: second support substrate 310: Seal 320: Spacer 330: Wiring

Claims

1. A liquid crystal display device comprising, in order, a first substrate having a switching element, a liquid crystal layer including liquid crystal molecules, and a second substrate having a counter electrode; A display region includes a plurality of pixels arranged in a matrix, Each of the plurality of pixels includes a reflective liquid crystal portion and a self-luminous element portion, In the reflective liquid crystal portion, the first substrate includes a reflector, a covering layer, and a pixel electrode in this order toward the liquid crystal layer, and does not include a switching element; the reflector, the pixel electrodes, the liquid crystal layer and the counter electrode constitute a reflective liquid crystal display element of a bistable liquid crystal display mode, In the self-luminous element section, the first substrate includes the switching element, a self-luminous display element including a first electrode, an organic layer, and a second electrode, and the covering layer disposed on the liquid crystal layer side of the self-luminous display element, The display device according to claim 1, wherein the covering layer is provided continuously on the reflective liquid crystal portion and the self-luminous element portion.

2. a non-display area provided around the display area, and wiring provided in the non-display area of ​​the first substrate, 2. The display device according to claim 1, wherein, in the non-display area, the counter electrode and the wiring are connected, and the pixel electrode and the wiring are connected.

3. the liquid crystal layer is in one of a first stable state and a second stable state in which the alignment states of the liquid crystal molecules are different from each other when a voltage less than a threshold value is applied between the pixel electrode and the counter electrode and no voltage is applied; 2. The display device according to claim 1, wherein the first stable state and the second stable state are switched by applying a voltage having a pulse waveform between the pixel electrode and the counter electrode.

4. The display device according to claim 1 , wherein the covering layer is provided continuously over the plurality of pixels.

5. The display device according to claim 1 , wherein the reflector is disposed in the same layer as the first electrode.

6. Further, the liquid crystal display device includes a vertical alignment film disposed between the first substrate and the liquid crystal layer, and a grating layer disposed between the second substrate and the liquid crystal layer, When a voltage less than a threshold value is applied between the pixel electrode and the counter electrode, the liquid crystal layer is in one of a first stable state in which the liquid crystal molecules are vertically aligned and a second stable state in which the liquid crystal molecules are HAN aligned, 2. The display device according to claim 1, wherein the first stable state and the second stable state are switched by applying a voltage having a pulse waveform between the pixel electrode and the counter electrode.

7. 7. The display device according to claim 6, wherein in the first stable state, a pretilt angle of the liquid crystal molecules on the first substrate side is 85° or more and 90° or less, and a pretilt angle of the liquid crystal molecules on the second substrate side is 85° or more and 90° or less.

8. 7. The display device according to claim 6, wherein in the second stable state, a pretilt angle of the liquid crystal molecules on the first substrate side is 85° or more and 90° or less, and a pretilt angle of the liquid crystal molecules on the second substrate side is 0° or more and 5° or less.

9. Further, the liquid crystal display device includes a horizontal alignment film having a pretilt and disposed between the first substrate and the liquid crystal layer, and a grating layer disposed between the second substrate and the liquid crystal layer, When a voltage less than a threshold value is applied between the pixel electrode and the counter electrode, the liquid crystal layer is in either a first stable state in which the liquid crystal molecules are in a TN orientation or a second stable state in which the liquid crystal molecules are in a HAN orientation; 2. The display device according to claim 1, wherein the first stable state and the second stable state are switched by applying a voltage having a pulse waveform between the pixel electrode and the counter electrode.

10. In the first stable state, a pretilt angle of the liquid crystal molecules on the first substrate side is 3° or more and 5° or less, and a pretilt angle of the liquid crystal molecules on the second substrate side is 0° or more and 5° or less, 10. The display device according to claim 9, wherein, in a plan view, an angle between the alignment direction of the liquid crystal molecules on the first substrate side and the alignment direction of the liquid crystal molecules on the second substrate side is 80° or more and 90° or less.

11. 10. The display device according to claim 9, wherein in the second stable state, a pretilt angle of the liquid crystal molecules on the first substrate side is greater than or equal to 3° and less than or equal to 5°, and a pretilt angle of the liquid crystal molecules on the second substrate side is greater than or equal to 85° and less than or equal to 90°.

12. Further, the liquid crystal display device includes a weak anchoring alignment film disposed between the first substrate and the liquid crystal layer, and a strong anchoring alignment film disposed between the second substrate and the liquid crystal layer, the liquid crystal layer is in one of a first stable state in which the liquid crystal molecules are homogeneously aligned and a second stable state in which the liquid crystal molecules on the first substrate side are twisted in a planar view by 180° rotation from the first stable state when no voltage is applied, in which a voltage less than a threshold value is applied between the pixel electrodes and the counter electrode; 2. The display device according to claim 1, wherein the first stable state and the second stable state are switched by applying a voltage having a pulse waveform between the pixel electrode and the counter electrode.

13. In the first stable state, a pretilt angle of the liquid crystal molecules on the first substrate side is 0° or more and 5° or less, and a pretilt angle of the liquid crystal molecules on the second substrate side is 5° or more and 10° or less, 13. The display device according to claim 12, wherein, in a plan view, an angle between an alignment direction of the liquid crystal molecules on the first substrate side and an alignment direction of the liquid crystal molecules on the second substrate side is greater than or equal to 0° and less than or equal to 10°.

14. In the second stable state, a pretilt angle of the liquid crystal molecules on the first substrate side is 0° or more and 5° or less, and a pretilt angle of the liquid crystal molecules on the second substrate side is 5° or more and 10° or less, In a plan view, an angle between an alignment direction of the liquid crystal molecules on the first substrate side and an alignment direction of the liquid crystal molecules on the second substrate side is equal to or greater than 0° and equal to or less than 10°; 13. The display device according to claim 12, wherein the liquid crystal molecules are aligned in a twisted manner by 170° or more and 180° or less in a plane from the first substrate side to the second substrate side.

15. 2. The display device according to claim 1, wherein the reflector has an uneven surface on the side facing the liquid crystal layer.

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