Transparent liquid crystal display device

Abstract

In a transparent liquid crystal display device, appropriate information is displayed on each of the two display surfaces. [Solution] The transparent liquid crystal display device 100 comprises a transparent liquid crystal display 1, TN liquid crystal displays 2 and 3, and a global controller 110. The global controller 110 performs display control that repeats a first display period and a second display period. During the first display period, the global controller 110 displays first information to be displayed on the first surface s11 side of the transparent liquid crystal display, transitions the TN liquid crystal display 2 to a transparent state, and transitions the TN liquid crystal display 3 to a black display state. During the second display period, the global controller 110 displays second information to be displayed on the second surface s12 side of the transparent liquid crystal display 1, transitions the TN liquid crystal display 2 to a black display state, and transitions the TN liquid crystal display 3 to a transparent state.

Description

Technical Field

[0001] The present invention relates to a transparent liquid crystal display device.

Background Art

[0002] A transparent display device is known in which a user can view information such as an image from a first surface and a second surface facing the first surface.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the transparent display device of the above technology, a user on the first surface side and a user on the second surface side facing the first surface can each recognize an image or the like. However, since the same image is viewed from each of the first surface and the second surface, in some cases, even if an appropriate image is displayed on one side, an appropriate image may not be displayed on the other side. Such a phenomenon is more easily understood, for example, when considering the case of displaying characters. That is, in the character image displayed on one side, the user can recognize the character from the character image, but in the character image displayed on the other side, since the character appears on the back side, it becomes difficult for the user to recognize the character from the character image.

[0005] In a transparent liquid crystal display device, it is desired to display appropriate information on each of both display surfaces.

Means for Solving the Problems

[0006] A transparent liquid crystal display device according to one embodiment includes a transparent liquid crystal display unit having a first surface and a second surface opposite to the first surface, a first display unit, a second display unit, and a control unit that controls the display of the transparent liquid crystal display unit, the first display unit, and the second display unit. The transparent liquid crystal display unit has a first substrate having the first surface, a second substrate having the second surface, a display layer disposed between the first substrate and the second substrate and capable of transitioning between a transparent state that transmits light and a display state that displays information, and a display area provided in the region where the first substrate, the second substrate, and the display layer overlap, and the information is displayed so as to be visible from the first surface side and the second surface side. In the first display unit, one surface of the substrate is disposed on the first surface, and the region covering the display area is capable of transitioning between a black display state that displays black and a transparent state that transmits light. In the second display unit, one surface of the substrate is disposed on the second surface, and the region covering the display area is capable of transitioning between a black display state that displays black and a transparent display state that transmits light. The control unit performs display control that repeats a first display period and a second display period. During the first display period, it displays first information to be displayed on the first side of the transparent liquid crystal display unit, transitions the first display unit to the transparent state, and transitions the second display unit to the black display state. During the second display period, it displays second information to be displayed on the second side of the transparent liquid crystal display unit, transitions the first display unit to the black display state, and transitions the second display unit to the transparent state. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram showing an example of the configuration of a transparent liquid crystal display device according to the first embodiment. [Figure 2] Figure 2 shows an example of the configuration of the transparent liquid crystal display of the first embodiment. [Figure 3] Figure 3 is a perspective view showing an overview of an example of the configuration of the main body of the transparent liquid crystal display according to the first embodiment. [Figure 4] Figure 4 is a cross-sectional view along line AA in Figure 3. [Figure 5]Figure 5 shows an example of the circuit configuration formed on the body of the transparent liquid crystal display of the first embodiment. [Figure 6] Figure 6 is a schematic diagram showing an example of the first double-sided view of the first embodiment. [Figure 7] Figure 7 is a schematic diagram showing an example of a one-sided view of the first embodiment. [Figure 8] Figure 8 is a schematic diagram showing an example of a one-sided view of the first embodiment. [Figure 9] Figure 9 shows an example of high-speed switching control according to the first embodiment. [Figure 10] Figure 10 is a diagram illustrating an example of the display of the transparent liquid crystal display device of the first embodiment. [Figure 11] Figure 11 is a diagram illustrating the operation of the transparent liquid crystal display device of the first embodiment. [Figure 12] Figure 12 is a diagram illustrating a modified example of the display control of the first embodiment. [Figure 13] Figure 13 is a schematic diagram showing an example of the configuration of a transparent liquid crystal display device according to the second embodiment. [Figure 14] Figure 14 is a schematic diagram showing an example of display control for a transparent liquid crystal display device according to the second embodiment. [Figure 15] Figure 15 is a schematic diagram showing an example of display control for a transparent liquid crystal display device according to the second embodiment. [Figure 16] Figure 16 is a schematic diagram showing an example of display control for a transparent liquid crystal display device according to the second embodiment. [Figure 17] Figure 17 shows an example of high-speed switching control according to the second embodiment. [Modes for carrying out the invention]

[0008] The embodiments will be described below with reference to the drawings.

[0009] This disclosure is merely an example, and any modifications that maintain the spirit of this disclosure while being appropriately conceivable by a person skilled in the art are naturally included within the scope of this disclosure.

[0010] Also, for the purpose of making the description clearer, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual embodiment, but this is merely an example and does not limit the interpretation of the present disclosure. In this specification and each figure, elements similar to those already shown in the figures may be denoted by the same reference numerals, and detailed descriptions may be appropriately omitted.

[0011] For the purpose of explanation, when explaining the processing by a program, the program, function, processing unit, etc. may be described as the main subject, but the hardware main body thereof is a processor, or a controller, device, computer, device, etc. composed of such a processor. The computer executes processing according to the program read onto the memory while appropriately using resources such as a memory and a communication interface by the processor. Thereby, a predetermined function, processing unit, etc. are realized. The processor is composed of, for example, a semiconductor device such as a CPU / MPU or GPU. The processing is not limited to software program processing and can also be implemented by a dedicated circuit. Applicable dedicated circuits include FPGA, ASIC, CPLD, etc.

[0012] The program may be pre-installed as data in the target computer, or may be distributed as data from the program source to the target computer. The program source may be a program distribution server on a communication network, or a non-transitory computer-readable storage medium, such as a memory card or a disk. The program may be composed of a plurality of modules. The computer device may be composed of a plurality of devices. The computer device may be composed of a client-server device, a cloud computing device, an IoT device, etc. Various data and information are composed in a structure such as a table or a list, for example, but are not limited thereto. Expressions such as identification information, identifier, ID, name, number, etc. are mutually replaceable.

[0013] (First Embodiment) Hereinafter, the transparent liquid crystal display device 100 of the first embodiment will be described with reference to FIGS. 1 to 11. The transparent liquid crystal display device 100 of the first embodiment includes a transparent liquid crystal display 1, TN liquid crystal displays 2 and 3, and an overall controller 110 that controls these. The transparent liquid crystal display 1 displays information on a screen 20 having light transmissivity.

[0014] The transparent liquid crystal display device 100 can be installed and used at an arbitrary position. For example, the transparent liquid crystal display device 100 can be installed on a counter where people face each other, a window, a partition between people, a show window glass of a store, etc.

[0015] <Configuration of the transparent liquid crystal display device> FIG. 1 is a schematic diagram showing an example of the configuration of the transparent liquid crystal display device 100. As shown in FIG. 1, the transparent liquid crystal display device 100 includes a transparent liquid crystal display 1 (transparent liquid crystal display unit), TN liquid crystal displays 2 (first display unit), TN liquid crystal displays 3 (second display unit), and an overall controller 110 (control unit). The overall controller 110 includes controllers 111, 112, and 113. The controller 111 is a controller that performs display control of the transparent liquid crystal display 1. The controller 112 is a controller that performs display control of the TN liquid crystal display 2. The controller 112 causes a region covering the screen (display region) of the transparent liquid crystal display 1 of the TN liquid crystal display 2 to transition between a black display state in which black is displayed and a transparent state in which light is transmitted. The controller 113 is a controller that performs display control of the TN liquid crystal display 3. The controller 113 causes a region covering the screen (display region) of the transparent liquid crystal display 1 of the TN liquid crystal display 3 to transition between a black display state in which black is displayed and a transparent state in which light is transmitted.

[0016] The transparent liquid crystal display 1 and the TN liquid crystal displays 2 and 3 are arranged so that their display surfaces overlap. In Figure 1, the direction in which the display surfaces of the transparent liquid crystal display 1 and the TN liquid crystal displays 2 and 3 overlap is defined as the Z direction. The Y direction, which is perpendicular to the Z direction, is the vertical direction as shown in the figure, and the X direction, which is perpendicular to both the Z and Y directions, is the plane of the paper as shown in the figure. In Figure 1 and other figures, the transparent liquid crystal display 1 and the TN liquid crystal display 2, and the transparent liquid crystal display 1 and the TN liquid crystal display 3 are shown to be separated, but they may be in close contact with each other.

[0017] <Transparent LCD Display> Figure 2 is a schematic diagram showing an example of the configuration of the transparent liquid crystal display 1 of the first embodiment. The transparent liquid crystal display 1 comprises a transparent liquid crystal display which is a main body 10 and a controller 111 connected to the main body 10. The transparent liquid crystal display 1 has a first surface s11 and a second surface s12 facing the first surface s11. In the transparent liquid crystal display 1, information displayed on the transparent liquid crystal display is recognized by the user from both the first surface s11 side and the second surface s12 side. Here, the information is one of the following, for example, image information showing an image, video information showing a video, character information showing characters, or composite information that combines image information, video information, and character information. The following description will focus on the case where an image is displayed.

[0018] The transparent liquid crystal display 1 has a main body 10 which includes a first substrate 11, a second substrate 12, and a display layer 13 that constitute a screen 20. The controller 111 is electrically connected to the main body 10. The display layer 13 has a plurality of pixels which constitute a display area corresponding to the screen 20, as will be described later.

[0019] The main unit 10 and the screen 20 have a first surface s11 on the first substrate 11 side and a second surface s12 on the second substrate 12 side. The transparent liquid crystal display 1 can display information such as images to the user on the first surface s11 side, or to the user on the second surface s12 side, by controlling the display layer 13. When information such as images or videos is displayed on the screen 20 in response to the control of the display layer 13 on the transparent liquid crystal display 1, the displayed image can be seen by both the user on the first surface s11 side and the user on the second surface s12 side.

[0020] The controller 111 displays information such as images and videos on the screen 20 by controlling the display state of the pixels in the liquid crystal layer, which is the display layer 13. The controller 111 may be built into the main unit 10 or connected to the outside of the main unit 10. For example, the control circuit constituting the controller 111 may be mounted on a part of the first board 11 or the second board 12, in addition to the drive circuit. The controller 111 may also be an external device such as a PC connected to the main unit 10. In addition, although not shown in the figures, the main unit 10 may have a microphone, speaker, lamp, etc. installed or connected to it.

[0021] The transparent liquid crystal display 1 shown in Figure 2, particularly the controller 111, may be connected to external devices through a predetermined communication interface, such as an HDMI interface. The transparent liquid crystal display 1 may also receive and input video signals from, for example, a video source device as an external device, and display them on the screen 20. In this case, the transparent liquid crystal display 1 functions as a monitor display.

[0022] <Example configuration of a transparent liquid crystal display> Next, an example of the configuration of the transparent liquid crystal display 1 will be explained using Figures 3 to 5. Figure 3 is a perspective view showing an overview of an example of the configuration of the main body 10 of the transparent liquid crystal display 1. Figure 4 is a cross-sectional view along line AA in Figure 3, and schematically shows the path of light emitted from the light source unit 50 of the transparent liquid crystal display 1. Figure 5 shows an example of the configuration of the circuit formed in the main body 10.

[0023] Figure 3 shows a perspective view of the transparent liquid crystal display, which is the main body 10, mainly from the perspective of the first surface s11. The transparent liquid crystal display, which is the main body 10, has a first substrate 11, a second substrate 12, a display layer 13, a light source unit 50, and a drive circuit 70. In the Z direction, the first substrate 11, the display layer 13, the second substrate 12, and the second surface s12 are arranged from the first surface s11 side.

[0024] The first substrate 11 is a counter substrate, the second substrate 12 is an array substrate, and the display layer 13 is a liquid crystal layer. The pixels (PIX) of the display layer 13 of the screen 20 emit light in all directions.

[0025] In Figure 3, in accordance with the coordinate system of Figure 1, the direction along the thickness direction of the transparent liquid crystal display, which is the main body 10, is defined as the Z direction. In the XY plane perpendicular to the Z direction, the direction in which one side of the transparent liquid crystal display extends is defined as the X direction, and the direction intersecting the X direction is defined as the Y direction. Furthermore, in the coordinate system (x,y) within the screen 20, the x direction corresponding to the X direction is the horizontal direction (horizontal direction within the screen), and the y direction corresponding to the Y direction is the vertical direction (vertical direction within the screen). In this embodiment, the screen 20 is a vertically elongated screen where the size in the Y direction (y direction) is larger than the size in the X direction (x direction), but it is not limited to this.

[0026] The first surface s11 has a display area DA corresponding to the screen 20 and a peripheral area PFA. In this embodiment, the peripheral area PFA is also considered part of the screen 20. The display area DA constituting the screen 20 is located in the region where the first substrate 11, the second substrate 12, and the display layer 13 overlap when viewed in a plan view in the Z direction. The peripheral area PFA is located outside the display area DA. The boundary between the display area DA and the peripheral area PFA is indicated by a dashed line.

[0027] The display area DA is the area where an image or video is formed in response to an input signal supplied from an external source. The display area DA is the effective area where an image or video is displayed when viewed in a planar view, for example, when viewing the first surface s11 or the second surface s12 in the Z direction. Multiple pixels PIX are formed in a matrix in the display layer 13 corresponding to the display area DA.

[0028] The peripheral area (PFA) is the area surrounding the display area (DA), including all four sides; in other words, it is the frame area, and no image or video is displayed there.

[0029] As shown in Figure 3, in this example, the second substrate 12 has a greater width in the Y direction than the first substrate 11. The second substrate 12 has a region 30 that extends to one side in the Y direction on the first surface s11 side, which in this embodiment is the left-hand side region. The light source unit 50 and the drive circuit 70 are mounted in this region 30.

[0030] The light source unit 50 is positioned along the peripheral area PFA on the left side of the screen 20. The light source unit 50 generates light for liquid crystal display on the display layer 13 and supplies it to the display layer 13.

[0031] The drive circuit 70 generates and supplies electrical signals for driving the first substrate 11, the second substrate 12, the display layer 13, and the light source unit 50. In Figure 3, a portion of the signal wiring that transmits signals for driving the liquid crystal corresponding to the pixels PIX in the transparent liquid crystal display is schematically shown by dashed lines, specifically the gate line GL and source line SL which will be described later.

[0032] The transparent liquid crystal display 1 may also have components other than those shown in Figure 3, such as a control circuit, a flexible printed circuit board, and a housing. Part of the drive circuit may be mounted on the peripheral area PFA. The housing may, for example, fix the first substrate 11, the display layer 13, and the second substrate 12. These elements are omitted in Figure 3. In this embodiment, the display area DA is rectangular, but is not limited to this, and may be other shapes such as polygons or circles. Also, in this example, the light source unit 50 and the drive circuit 70 are mounted on area 30, but are not limited to this. As a variation, a light source substrate and a drive circuit board (not shown) are attached to the peripheral area PFA separately from the first substrate 11 and the second substrate 12, and a configuration in which the light source unit 50 is mounted on the light source substrate or the drive circuit 70 is mounted on the drive circuit board is also possible.

[0033] In the YZ cross-sectional view of Figure 4, the optical path of light emitted from the light source unit 50 and the state of the liquid crystal in the transparent liquid crystal display, which is the main body 10, will be explained. The transparent liquid crystal display, which is the main body 10, has a first substrate 11 and a second substrate 12 that are bonded together as a display layer 13, facing each other via a liquid crystal layer LQL. The first substrate 11 and the second substrate 12 are arranged in the Z direction, which is the thickness direction of the transparent liquid crystal display, via the liquid crystal layer LQL. In other words, the first substrate 11 and the second substrate 12 face each other in the Z direction, which is the thickness direction of the transparent liquid crystal display.

[0034] The array substrate, which is the second substrate 12, has a liquid crystal layer LQL and a front surface 12f facing the first substrate 11. The opposing substrate, which is the first substrate 11, has the front surface 12f of the second substrate 12 and a back surface 11b facing the liquid crystal layer LQL. The liquid crystal layer LQL, which contains liquid crystals, is located between the front surface 12f of the second substrate 12 and the back surface 11b of the first substrate 11. In other words, the liquid crystal layer LQL is an optical modulation element.

[0035] The second substrate 12 is an array substrate in which multiple transistors (in other words, transistor elements) that serve as switching elements (in other words, active elements) are arranged in an array. The first substrate 11 can be referred to as a counter substrate, meaning that it is a substrate positioned opposite the array substrate, which is the second substrate 12.

[0036] The transparent liquid crystal display (LCD) main unit 10 has the function of modulating the light passing through the liquid crystal of the LQL by controlling the state of the electric field formed around the LQL via the switching element. The display area DA is provided in the area that overlaps with the LQL.

[0037] The first substrate 11 and the second substrate 12 are bonded together via a sealing portion (in other words, a sealing material) SLM. The sealing portion SLM is positioned to surround the periphery of the display area DA. Inside the sealing portion SLM is the liquid crystal layer LQL. The sealing portion SLM serves to encapsulate the liquid crystal between the first substrate 11 and the second substrate 12, and also acts as an adhesive to bond the first substrate 11 and the second substrate 12 together.

[0038] The light source unit 50 is positioned opposite one side surface 11s1 of the first substrate 11. The light source light L1 emitted from the light source unit 50 is schematically shown by a dashed line. The light source light L1 emitted from the light source unit 50 in the Y direction propagates in the direction away from the side surface 11s1, in this embodiment, direction Y2, while being reflected by the second surface s12, which is the back surface 12b of the second substrate 12, and the first surface s11, which is the front surface 11f of the first substrate 11, as shown in the figure. In the propagation path of the light source light L1, the back surface 12b of the second substrate 12 and the front surface 11f of the first substrate 11 are interfaces between a medium with a high refractive index and a medium with a low refractive index. Therefore, if the angle of incidence at which the light source light L1 is incident on the front surface 11f and the back surface 12b is greater than the critical angle, the light source light L1 undergoes total internal reflection at the front surface 11f and the back surface 12b.

[0039] The liquid crystal in the liquid crystal layer (LQL) is a polymer-dispersed liquid crystal, containing liquid crystalline polymers and liquid crystal molecules. The liquid crystalline polymers are formed in streaks, and the liquid crystal molecules are dispersed in the gaps between the polymers. Both the liquid crystalline polymers and the liquid crystal molecules exhibit optical anisotropy or refractive index anisotropy. The responsiveness of the liquid crystalline polymers to electric fields is lower than that of the liquid crystal molecules. The orientation direction of the liquid crystalline polymers hardly changes regardless of the presence or absence of an electric field.

[0040] On the other hand, the orientation direction of the liquid crystal molecules changes in response to the electric field when a voltage above a threshold is applied to the liquid crystal. When no voltage is applied to the liquid crystal, the optical axes of the liquid crystalline polymer and the liquid crystal molecules are parallel to each other, and the light source L1 incident on the liquid crystal layer LQL is transmitted through the liquid crystal layer LQL with almost no scattering. This state is sometimes described as the transparent state.

[0041] When a voltage is applied to a liquid crystal, the optical axes of the liquid crystalline polymer and liquid crystal molecules intersect with each other, and the light source L1 incident on the liquid crystal is scattered within the liquid crystal layer LQL. This state is sometimes described as a scattering state (or, in other words, a display state).

[0042] The main unit 10, a transparent liquid crystal display, specifically the control circuit and drive circuit 70, controls the transparent state and the scattered state (in other words, the display state) by controlling the orientation of the liquid crystals in the propagation path of the light source L1. In the scattered state, the light source L1 is emitted as emitted light L2 by the liquid crystals and exits the transparent liquid crystal display from the front surface 11f (first surface s11) and the back surface 12b (second surface s12). This emitted light L2 corresponds to the displayed image light.

[0043] Furthermore, background light L3 incident from the second surface s12, which is the back surface 12b, passes through the second substrate 12, the liquid crystal layer LQL, and the first substrate 11, and is emitted to the outside from the first surface s11, which is the front surface 11f.

[0044] These emitted light L2 and background light L3 are visible to the user on the first surface s11 side. Emitted light L2 corresponds to image light DGL1, and background light L3 corresponds to background light BGL1. The user can recognize the emitted light L2 and background light L3 in combination. Thus, this transparent liquid crystal display is a display panel that has the characteristic of allowing the user to recognize the displayed image and background in combination.

[0045] In the transparent liquid crystal display shown in Figure 4, the light source unit 50 is positioned in a location that does not overlap with the display area DA in a plan view, in order to ensure visible light transmittance of the first surface s11 and the second surface s12. Furthermore, this transparent liquid crystal display reflects light from the light source L1 by utilizing the refractive index difference between the first substrate 11 and the second substrate 12, which function as light guide members, and the surrounding air layer. As a result, this transparent liquid crystal display has a mechanism that delivers light to the side surface 11s2 opposite to the light source unit 50.

[0046] Figure 5 illustrates an example of the circuit configuration of the transparent liquid crystal display, which is the main unit 10. Figure 5 shows an example of the configuration of the drive circuit 70, the light source unit 50, and the pixels PIX of the display area DA (Figure 3). The drive circuit 70 is connected to a control unit 90 which has a control circuit for controlling the display of the image. The control unit 90 is included in the overall controller 110 shown in Figure 1, for example. However, the control unit 90 may be mounted on the transparent liquid crystal display together with the drive circuit 70.

[0047] The drive circuit 70 includes a signal processing circuit 71, a pixel control circuit 72, a gate drive circuit 73, a source drive circuit 74, a common potential drive circuit 75, and a light source control unit 52. The light source unit 50 also includes, for example, a light-emitting diode element 51r (for example, red), a light-emitting diode element 51g (for example, green), and a light-emitting diode element 51b (for example, blue).

[0048] The signal processing circuit 71 comprises an input signal analysis unit 711, a storage unit 712, and a signal adjustment unit 713. The input signal VS is input to the input signal analysis unit 711 of the signal processing circuit 71 from the control unit 90 via a wiring path such as a flexible printed circuit board (not shown). The input signal analysis unit 711 performs analysis processing based on the input signal VS and generates an input signal VCS. The input signal VCS is, for example, a signal that determines what gradation value to assign to each pixel PIX (Figure 3) based on the input signal VS.

[0049] The signal adjustment unit 713 generates an input signal VCSA from the input signal VCS input from the input signal analysis unit 711. The signal adjustment unit 713 sends the input signal VCSA to the pixel control circuit 72 and the light source control signal LCSA to the light source control unit 52. The light source control signal LCSA is a signal that includes information about the amount of light from the light source unit 50, which is set according to the input grayscale value to the pixel PIX.

[0050] The pixel control circuit 72 generates a horizontal drive signal HDS and a vertical drive signal VDS based on the input signal VCSA. For example, in this embodiment, multiple pixels PIX are driven in a field sequential manner. Therefore, the pixel control circuit 72 generates the horizontal drive signal HDS and the vertical drive signal VDS for each color that the light source unit 50 can emit light.

[0051] The gate drive circuit 73 sequentially selects gate lines GL (in other words, signal lines) of the transparent liquid crystal display within one vertical scanning period based on the horizontal drive signal HDS. The order of selection of gate lines GL is arbitrary. As shown in Figure 3, multiple gate lines GL extend in the X direction and are arranged in multiples along the Y direction.

[0052] The source drive circuit 74 supplies a gradation signal corresponding to the output gradation value of each pixel PIX to each source line SL (in other words, signal wiring) of the transparent liquid crystal display within one horizontal scanning period, based on the vertical drive signal VDS. As shown in Figure 3, multiple source lines SL extend in the Y direction (y direction) and are arranged in multiples along the X direction (x direction). One pixel PIX is formed at each intersection of the gate line GL and the source line SL.

[0053] A switching element Tr is formed at each of the points where the gate line GL and the source line SL intersect. The multiple gate lines GL and multiple source lines SL correspond to the multiple signal lines that transmit drive signals for driving the liquid crystal in the liquid crystal layer LQL in Figure 4.

[0054] As the switching element Tr, for example, a thin-film transistor is used. The type of thin-film transistor is not particularly limited. One of the source electrode and drain electrode of the switching element Tr is connected to the source line SL, the gate electrode is connected to the gate line GL, and the other of the source electrode and drain electrode is connected to one end of the capacitance of the polymer-dispersed liquid crystal LC (corresponding to the liquid crystal of the liquid crystal layer LQL in Figure 4). One end of the capacitance of the polymer-dispersed liquid crystal LC is connected to the switching element Tr via the pixel electrode PE, and the other end is connected to the common potential wiring CML via the common electrode CE. In addition, a retaining capacitance HC is generated between the pixel electrode PE and the retaining capacitance electrode electrically connected to the common potential wiring CML. The common potential wiring CML is supplied from the common potential driving circuit 75. The wiring path connected to the common electrode CE in Figure 5 is formed, for example, on the first substrate 11 in Figure 3. In Figure 5, the wiring formed on the first substrate 11 is shown by a dotted line.

[0055] In the configuration example shown in FIG. 5, the drive circuit 70 includes the light source control unit 52. As a modification, the light source unit 50 and the light source control unit 52 may be provided separately from the drive circuit 70. As described above, when the light source unit 50 is mounted on a light source substrate different from the second substrate 12, the light source control unit 52 may be formed on the light source substrate or may be formed on an electronic component mounted on the light source substrate.

[0056] <TN liquid crystal display> Next, the TN liquid crystal displays 2 and 3 will be described. As shown in FIG. 1, the TN liquid crystal display 2 has a first surface s21 and a second surface s22 facing the first surface s21. The TN liquid crystal display 3 has a first surface s31 and a second surface s32 facing the first surface s31. The transparent liquid crystal display device 10 comprises the second surface s22 of the TN liquid crystal display 2 and the first surface s11 of the transparent liquid crystal display 1 facing each other, and the second surface s12 of the transparent liquid crystal display 1 and the first surface s31 of the TN liquid crystal display 3 facing each other. That is, the transparent liquid crystal display device 10 is configured such that the screen (display area) 20 of the transparent liquid crystal display 1 is sandwiched between the display areas of the TN liquid crystal displays 2 and 3.

[0057] The TN liquid crystal display 2 can transition between a black display state in which black is displayed and a transparent display state in which light is transmitted based on a control instruction from the controller 112. The TN liquid crystal display 3 can transition between a black display state in which black is displayed and a transparent display state in which light is transmitted based on a control instruction from the controller 113.

[0058] TN liquid crystal displays 2 and 3 control the twisting state of the liquid crystal layer by the voltage strength, thereby adjusting the intensity of light transmitted from the backlight and transitioning between a black display state and a transparent display state. TN liquid crystal displays 2 and 3 are configured so that horizontally aligned liquid crystal layers are sandwiched between polarizing filters that are offset by 90 degrees from each other. When the voltage is off, the liquid crystal molecules in the liquid crystal layer face the same direction near each polarizing filter, resulting in a stepped twisting state within the liquid crystal layer. Since the polarization of the backlight light also rotates along with the twist, light is transmitted when the voltage is off. At this time, TN liquid crystal displays 2 and 3 are in a transparent display state. On the other hand, when voltage is applied, the liquid crystal layer corresponding to the pixel rises vertically, breaking the twisted structure. As a result, the polarization stops rotating at the maximum voltage, and the backlight light is blocked. At this time, TN liquid crystal displays 2 and 3 are in a black display state.

[0059] <Display Control> Next, the display control of the transparent liquid crystal display device 100 will be described. Figure 6 is a schematic diagram showing an example of the first double-sided viewing state. The first double-sided viewing state is a state in the transparent liquid crystal display device 100 where the same information displayed on the transparent liquid crystal display 1 is visible from both the TN liquid crystal display 2 side and the TN liquid crystal display 3 side. Therefore, the light from arrow AW1 passes through the TN liquid crystal display 2, the transparent liquid crystal display 1, and the TN liquid crystal display 3. Also, the light from arrow AW2 passes through the TN liquid crystal display 3, the transparent liquid crystal display 1, and the TN liquid crystal display 2. As a result, user U1 located to the left of the TN liquid crystal display 2 and user U2 located to the right of the TN liquid crystal display 3 can each see the information displayed on the transparent liquid crystal display 1. However, the information is seen in the opposite direction for one of them.

[0060] For example, as shown in Figure 6, the transparent liquid crystal display 1 displays an image of the sun Su. The TN liquid crystal displays 2 and 3 are both transparent (in a transparent display state). Therefore, user U1 can view the image of the sun Su displayed on the transparent liquid crystal display 1 via the TN liquid crystal display 2. User U2 can also view the image of the sun Su displayed on the transparent liquid crystal display 1 via the TN liquid crystal display 3. In other words, in the first double-sided viewing state, both user U1 and user U2 can view the same image of the sun Su.

[0061] Figures 7 and 8 are schematic diagrams illustrating an example of a one-sided viewing state. A one-sided viewing state is a condition in which information displayed on the transparent liquid crystal display 1 is visible from either the TN liquid crystal display 2 side or the TN liquid crystal display 3 side. Figure 7 shows a state in which information displayed on the transparent liquid crystal display 1 is visible only from the TN liquid crystal display 2 side. Figure 8 shows a state in which information displayed on the transparent liquid crystal display 1 is visible only from the TN liquid crystal display 3 side.

[0062] For example, as shown in Figure 7, if the TN liquid crystal display 2 is transparent (in a transparent display state) and the TN liquid crystal display 3 is black (in a black display state), user U1 can see the image of the sun Su (first information) displayed on the transparent liquid crystal display 1, but user U2 can only see black.

[0063] For example, as shown in Figure 8, when TN liquid crystal display 2 is black (black display state) and TN liquid crystal display 3 is transparent (transparent display state), user U2 can see the image of the moon Mo (second information) displayed on transparent liquid crystal display 1, but user U1 can only see black. In other words, according to the examples in Figures 7 and 8, user U1 and user U2 can each see different information. That is, user U1 can see the sun Su, and user U2 can see the moon Mo.

[0064] Figure 9 shows an example of high-speed switching control that rapidly switches between the states described in Figures 7 and 8. By executing this high-speed switching control, a second double-sided viewing state can be achieved. The second double-sided viewing state is a state in the transparent liquid crystal display device 100 in which different information displayed on the transparent liquid crystal display 1 can be viewed on the TN liquid crystal display 2 side and the TN liquid crystal display 3 side.

[0065] As shown in Figure 9, the controller 111 performs display control that repeats a first display period and a second display period. The first display period is time t1, and the second display period is time t2. Time t1 and time t2 are, for example, 1 / 120th of a second each. In other words, the information is displayed by switching every 120Hz. Note that time t1 and time t2 may each be less than 1 / 120th of a second. The point is that time t1 and time t2 should be short periods of time that allow for high-speed display switching.

[0066] During the first display period, controller 111 displays an image of the sun Su on the transparent liquid crystal display 1, controller 112 transitions the TN liquid crystal display 2 to a transparent display state, and controller 113 transitions the TN liquid crystal display 3 to a black display state. As a result, during the first display period, user U1 can recognize the image of the sun Su displayed on the transparent liquid crystal display 1 via the TN liquid crystal display 2 in the transparent display state, but user U2 cannot recognize the image of the sun Su because the TN liquid crystal display 3 is in the black display state.

[0067] During the second display period, controller 111 displays an image of the moon (Mo) on the transparent liquid crystal display 1, controller 112 transitions the TN liquid crystal display 2 to a black display state, and controller 113 transitions the TN liquid crystal display 3 to a transparent display state. As a result, during the second display period, user U1 cannot see the image of the moon (Mo) displayed on the transparent liquid crystal display 1 due to the black display state of the TN liquid crystal display 2, but user U2 can see the image of the moon (Mo) through the transparent display state of the TN liquid crystal display 3.

[0068] In the next first display period, time t3, the same display control as at time t1 is performed, and in the next second display period, time t4, the same display control as at time t2 is performed. In this way, the display control, which repeats the first and second display periods, is executed at high speed.

[0069] Figure 10 illustrates an example of the display on the transparent liquid crystal display device 100 when the overall controller 110 performs the high-speed switching control shown in Figure 9. By performing the high-speed switching control, as shown in Figure 10, on the user U1 side, the display control is performed such that the image of the sun Su is displayed at 120Hz, black is displayed at 120Hz, the image of the sun Su is displayed at 120Hz, and black is displayed at 120Hz. As a result, the image that user U1 can see is the image of the sun Su. On the other hand, on the user U2 side, the transparent liquid crystal display device 100 is controlled to display black at 120Hz, the image of the moon Mo is displayed at 120Hz, black is displayed at 120Hz, and the image of the moon Mo is displayed at 120Hz. As a result, the image that user U2 can see is the image of the moon Mo.

[0070] Figure 11 is a diagram illustrating the operation of the transparent liquid crystal display device 100 when high-speed switching control is performed. As shown in Figure 11, user U1 can view the image of the sun Su displayed on the transparent liquid crystal display 1 via the TN liquid crystal display 2 in the transparent display state, but cannot view the image of the moon Mo. On the other hand, user U2 can view the image of the moon Mo displayed on the transparent liquid crystal display 1 via the TN liquid crystal display 3 in the transparent display state, but cannot view the image of the sun Su. In other words, in the second double-sided viewing state, user U1 and user U2 can view different information.

[0071] Whether the transparent liquid crystal display device 100 operates in a first double-sided viewing state or a second double-sided viewing state can be determined, for example, based on instructions from a higher-level device connected to the overall controller 110.

[0072] As explained above, the transparent liquid crystal display device 100 can display information that should be shown to user U1 on the user U1 side, and information that should be shown to user U2 on the user U2 side. In other words, the transparent liquid crystal display device 100 can distinguish between information to be displayed on the TN liquid crystal display 2 side and information to be displayed on the TN liquid crystal display 3 side. Therefore, the transparent liquid crystal display device 100 can display appropriate information on each of the two display surfaces.

[0073] In the above embodiment, the case in which the transparent liquid crystal display device 100 uses TN liquid crystal displays 2 and 3 suitable for high-speed switching control was described, but the configuration for realizing the transparent liquid crystal display device 100 is not limited to this. For example, instead of a TN liquid crystal display, a chromism device or a dimming device may be used to transition the chromism device or dimming device between a black display state and a transparent display state.

[0074] Furthermore, due to the high-speed switching control of the transparent liquid crystal display device 100, for example, user U1 may perceive images for 120 Hz out of 60 Hz, but perceive black for the remaining 120 Hz. Therefore, information displayed on the transparent liquid crystal display 1 may appear dark. To prevent this, the transparent liquid crystal display device 100 may adjust the hue, brightness, and saturation of the displayed image. In other words, the overall controller 110 may adjust the hue, brightness, and saturation of the information displayed on the first side s11 according to the duration of the black display state on the TN liquid crystal display 2. The overall controller 110 may also adjust the hue, brightness, and saturation of the information displayed on the second side s12 according to the duration of the black display state on the TN liquid crystal display 3.

[0075] For example, the overall controller 110 adjusts the hue, brightness, and saturation of the information to be displayed, such as an image, so that the information is displayed brightly on the transparent liquid crystal display 1. In other words, it adjusts the information, such as an image that is displayed darkly, so that it is visible at the brightness it should be displayed at. As a result, even when the transparent liquid crystal display device 100 performs the high-speed switching control described above, it can allow the user to view the image at the brightness it should be displayed at.

[0076] In the above embodiment, the transparent liquid crystal display device 100 was described as switching between display surfaces that display information such as images, with a first display period of 120Hz and a second display period of 120Hz, for a total of 60Hz. However, the timing of switching displays is not limited to this.

[0077] <Variation> Figure 12 is a diagram illustrating a modified example of the display control of the transparent liquid crystal display device 100. As shown in Figure 12, in the transparent liquid crystal display device 100, both TN liquid crystal displays 2 and 3 are displaying black.

[0078] For example, if the overall controller 110 receives an instruction to display both sides in black, or an instruction to restrict the display of the image shown on the transparent liquid crystal display 1, the controller 112 transitions the TN liquid crystal display 2 to a black display state, and the controller 113 transitions the TN liquid crystal display 3 to a black display state. As a result, the transparent liquid crystal display device 100 can prevent users U1 and U2 from seeing the information displayed on the transparent liquid crystal display 1 based on the instruction to display both sides in black, or the instruction to restrict the display. This allows the transparent liquid crystal display device 100 to improve the security of information disclosure.

[0079] (Second Embodiment) The second embodiment differs from the first embodiment in the configuration of the transparent liquid crystal display and the TN liquid crystal display in the transparent liquid crystal display device. <Configuration of a transparent liquid crystal display> Figure 13 is a schematic diagram showing an example of the configuration of a transparent liquid crystal display device 200. As shown in Figure 13, the transparent liquid crystal display device 200 includes a TN liquid crystal display 4, transparent liquid crystal displays 5 and 6, and a global controller 210. The global controller 210 includes controllers 211, 212, and 213. Controller 211 is a controller that controls the display of the TN liquid crystal display 4. Controller 212 is a controller that controls the display of the transparent liquid crystal display 5. Controller 213 is a controller that controls the display of the transparent liquid crystal display 6.

[0080] The TN liquid crystal display 4 can transition between a black display state and a transparent display state based on control instructions from the controller 212. The transparent liquid crystal display 5 can transition between a transparent display state and a display state. The transparent liquid crystal display 6 can transition between a transparent display state and a display state.

[0081] The TN liquid crystal display 4 and the transparent liquid crystal displays 5 and 6 are arranged so that their display surfaces overlap. In Figure 13, the direction in which the display surfaces of the TN liquid crystal display 4 and the transparent liquid crystal displays 5 and 6 overlap is defined as the Z direction. The Y direction, which is perpendicular to the Z direction, is the vertical direction (up and down direction) as shown in the figure, and the X direction, which is perpendicular to both the Z and Y directions, is the plane of the paper as shown in the figure.

[0082] Figure 14 is a schematic diagram showing an example of display control of the transparent liquid crystal display device 200. In Figure 14, the TN liquid crystal display 4 is transparent (in a transparent display state), and the transparent liquid crystal display 6 is transparent (in a transparent display state). In this case, when an image of the sun Su is displayed on the transparent liquid crystal display 5, user U1 can see the sun Su displayed on the transparent liquid crystal display 5. On the other hand, user U2 can see the image of the sun Su displayed on the transparent liquid crystal display 5 through the transparent liquid crystal display 6 and the TN liquid crystal display 4. Even with this display control, the transparent liquid crystal display device 200 can achieve double-sided viewing.

[0083] Figure 15 is a schematic diagram showing an example of display control for the transparent liquid crystal display device 200. In Figure 15, the TN liquid crystal display 4 is black (black display state), the transparent liquid crystal display 5 displays an image of the sun Su, and the transparent liquid crystal display 6 displays an image of the moon Mo. In this case, user U1 can see the sun Su displayed on the transparent liquid crystal display 5, but is unable to see the image of the moon Mo displayed on the transparent liquid crystal display 6 because the black display of the TN liquid crystal display 4 is obstructing their view. On the other hand, user U2 can see the image of the moon Mo displayed on the transparent liquid crystal display 6, but is unable to see the image of the sun Su displayed on the transparent liquid crystal display 5 because the black display of the TN liquid crystal display 4 is obstructing their view. Even with this display control, the transparent liquid crystal display device 200 can achieve double-sided viewing.

[0084] Figure 16 is a schematic diagram showing an example of display control for the transparent liquid crystal display device 200. Figure 17 is a diagram showing an example of high-speed switching control that realizes the display states described in Figure 16.

[0085] In Figure 16, the TN liquid crystal display 4 transitions between transparent (transparent display state) and black (black display state), with the image of the sun Su displayed on the transparent liquid crystal display 5 and the image of the moon Mo displayed on the transparent liquid crystal display 6.

[0086] As shown in Figure 17, the TN liquid crystal display 4 is controlled to become transparent (transparent display state) when the image of the sun Su is displayed on the transparent liquid crystal display 5, and to become black (black display state) when the image of the moon Mo is displayed on the transparent liquid crystal display 6.

[0087] When the control is performed in this manner, as shown in Figure 16, user U1 can see the image of the sun Su displayed on the transparent liquid crystal display 5, but is unable to see the image of the moon Mo displayed on the transparent liquid crystal display 6 because of the black display on the TN liquid crystal display 4. On the other hand, user U2 can see the image of the moon Mo displayed on the transparent liquid crystal display 6, and furthermore, because the TN liquid crystal display 4 is transparent, can also see the image of the sun Su displayed on the transparent liquid crystal display 5. Even with this display control, the transparent liquid crystal display device 200 can achieve double-sided viewing.

[0088] Which of the two-sided views described above is to be performed can be determined, for example, based on instructions from a higher-level device connected to the overall controller 210.

[0089] Although various embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications are included. Furthermore, the embodiments described above are described in detail for the purpose of explaining the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. In addition, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. All of these are within the scope of the present invention. Furthermore, the numerical values ​​and other figures included in the text and figures are merely examples, and using different ones will not impair the effects of the present invention. [Explanation of symbols]

[0090] 1,5,6…Transparent LCD display, 2,3,4…TN LCD display, 20…Display area, 100,200…Transparent LCD display device, 110,210…Overall controller, 111,112,113,211,212,213…Controller, s11…First surface, s12…Second surface, Su…Sun, Mo…Moon, t1~t4…Time, U1,U2…User

Claims

1. A transparent liquid crystal display unit having a first surface and a second surface opposite to the first surface, The first display unit and The second display unit, The system comprises a transparent liquid crystal display unit, a first display unit, and a control unit for controlling the display of the second display unit, The transparent liquid crystal display unit is A first substrate having the first surface, A second substrate having the second surface, A display layer is disposed between the first substrate and the second substrate, and is capable of transitioning between a transparent state that transmits light and a display state that displays information. The first substrate, the second substrate, and a display area provided in the region where the display layer overlaps, The information is displayed so that it can be seen from the first and second surfaces. The first display unit is, One surface of the substrate is placed on the first surface, and the region covering the display area is capable of transitioning between a black display state that displays black and a transparent state that transmits light. The second display unit is, One side of the substrate is placed on the second surface, and the area covering the display area can transition between a black display state that displays black and a transparent display state that transmits light. The control unit, The display control is performed by repeating the first display period and the second display period. During the first display period, the first information to be displayed on the first side of the transparent liquid crystal display unit is displayed, the first display unit is transitioned to the transparent state, and the second display unit is transitioned to the black display state. During the second display period, the second information to be displayed on the second side is displayed on the transparent liquid crystal display unit, the first display unit is transitioned to the black display state, and the second display unit is transitioned to the transparent state. Transparent liquid crystal display device.

2. In the transparent liquid crystal display device according to claim 1, When the control unit receives an instruction to display black or limit the display, During the first and second display periods, The first display unit and the second display unit are transitioned to the black display state. Transparent liquid crystal display device.

3. A transparent liquid crystal display device according to claim 1, The first information and the second information are, respectively, image information representing an image, video information representing a video, character information representing characters, and composite information that combines the image information, video information, and character information. Transparent liquid crystal display device.

4. A transparent liquid crystal display device according to claim 1, The first display unit and the second display unit are TN liquid crystal display devices, Transparent liquid crystal display device.

5. A transparent liquid crystal display device according to claim 1, The first display period and the second display period are each 1 / 120th of a second or less. Transparent liquid crystal display device.

6. A transparent liquid crystal display device according to claim 1, The control unit adjusts the hue, brightness, and saturation of the first information displayed on the first surface according to the duration of the black display state shown on the first display unit. Transparent liquid crystal display device.

7. A transparent liquid crystal display device according to claim 6, The control unit adjusts the hue, brightness, and saturation of the first information so that it is displayed brightly on the transparent liquid crystal display unit. Transparent liquid crystal display device.

8. A transparent liquid crystal display device according to claim 6, Furthermore, the control unit adjusts the hue, brightness, and saturation of the second information displayed on the second side according to the duration of the black display state shown on the second display unit. Transparent liquid crystal display device.

9. A transparent liquid crystal display device according to claim 8, The control unit adjusts the hue, brightness, and saturation of the second information so that they are displayed brightly on the transparent liquid crystal display unit. Transparent liquid crystal display device.

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