Display device

Abstract

This display device comprising: a light guide plate; a light source positioned on a side surface of the light guide plate; a first liquid crystal panel positioned on a first surface of the light guide plate; a first reflective polarizing film positioned between the light guide plate and the first liquid crystal panel and configured to reflect a first direction-polarization component; a second liquid crystal panel positioned on a second surface of the light guide plate; and a second reflective polarizing film positioned between the light guide plate and the second liquid crystal panel and configured to reflect a second direction-polarization component, wherein the first direction and the second direction are different from each other, may implement a double-sided output display device having a small thickness.

Description

display device

[0001] The present invention relates to a double-sided display device.

[0002] As the information society develops, the demand for display devices is also increasing in various forms, and in response to this, recent display devices include liquid crystal displays (LCDs), field emission displays (FEDs), plasma display panels (PDPs), and electroluminescence devices.

[0003] Among these display devices, a liquid crystal display (LCD) is a device that includes an array substrate including a thin film transistor, which is a switching element for controlling on / off of each pixel area, an upper substrate including a color filter and / or a black matrix, a display panel including a liquid crystal material layer formed therebetween, a driving unit for controlling the thin film transistor, and a backlight unit (BLU) for providing light to the display panel, and an electric field applied between a pixel (PXL) electrode and a common voltage (Vcom) electrode provided in the pixel area, and the arrangement state of the liquid crystal layer is controlled and the transmittance of light is controlled accordingly to display an image.

[0004] In the case of such liquid crystal displays, there must be a backlight device that provides light from the outside, and such a backlight unit may include a light source, a light guide plate, a reflector, a top sheet, and other sub-units.

[0005] A typical display device outputs an image to only one side of the flat display device, and has a cover bottom or back cover on the other side.

[0006] Recently, there is a need for double-sided display devices that output images on both sides, rather than the single-sided display format for signage installed outdoors or in public spaces.

[0007] The present invention aims to provide a double-sided display device having a thin thickness.

[0008] A display device is provided, comprising: a light guide plate; a light source positioned on a side of the light guide plate; a first liquid crystal panel positioned on a first surface of the light guide plate; a first reflective polarizing film positioned between the light guide plate and the first liquid crystal panel and reflecting a first direction polarization component; a second liquid crystal panel positioned on a second surface of the light guide plate; and a second reflective polarizing film positioned between the light guide plate and the second liquid crystal panel and reflecting a second direction polarization component, wherein the first direction and the second direction are different from each other.

[0009] The first direction and the second direction may be perpendicular.

[0010] It may include a first incident polarizing film positioned on the inner surface of the first liquid crystal panel and allowing polarization components in the second direction to pass through; and a second incident polarizing film positioned on the inner surface of the second liquid crystal panel and allowing polarization components in the first direction to pass through.

[0011] It may include a first emission polarizing film positioned on the outer surface of the first liquid crystal panel and allowing polarization components in the first direction to pass through; and a second emission polarizing film positioned on the outer surface of the second liquid crystal panel and allowing polarization components in the second direction to pass through.

[0012] The above light guide plate may include prism patterns formed on both sides.

[0013] The light source is located on one side of the light guide plate, and the prism pattern may have an inclined surface facing one side and an inclined surface facing the other side at different angles.

[0014] The inclination angle (α) of the inclined surface on one side of the prism pattern may be greater than 45°, and the inclination angle (β) of the inclined surface on the other side of the prism pattern may be less than 45°.

[0015] The light source may be provided in pairs on one side and the other side of the light guide plate in the first direction, and the prism pattern may include an inclined surface symmetrical in the first direction.

[0016] The prism pattern located at the center of the first direction may be formed more densely than the prism pattern located adjacent to the light source.

[0017] The first reflective polarizing film and the second reflective polarizing film may include an optical pattern formed on a surface facing the light guide plate.

[0018] The display device of the present invention can implement a double-sided output display device having a thin thickness.

[0019] Light efficiency can be increased by minimizing the amount of light that is lost and not reused among the light passing through the optical sheet or reflected by the reflector.

[0020] Additionally, the number of missing parts can be reduced, thereby reducing manufacturing costs.

[0021] The effects that can be obtained from the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by a person having ordinary skill in the art to which the present invention belongs from the description below.

[0022] Figure 1 is a block diagram for explaining each component of the display device of the present invention.

[0023] Figure 2 is a perspective view showing an example of a display device of the present invention.

[0024] Figure 3 is a cross-sectional view illustrating a conventional display device.

[0025] Fig. 4 is a cross-sectional view showing an example of a display device of the present invention.

[0026] Figures 5 and 6 are drawings for explaining the path of light according to the arrangement of light sources.

[0027] Hereinafter, embodiments disclosed in this specification will be described in detail with reference to the attached drawings. Regardless of the drawing numbers, identical or similar components will be given the same reference numbers and redundant descriptions thereof will be omitted. The suffixes "module" and "part" used for components in the following description are assigned or used interchangeably only for the convenience of writing the specification, and do not in themselves have distinct meanings or roles. In addition, when describing the embodiments disclosed in this specification, if it is determined that a specific description of a related known technology may obscure the gist of the embodiments disclosed in this specification, a detailed description thereof will be omitted. In addition, the attached drawings are only intended to facilitate easy understanding of the embodiments disclosed in this specification, and the technical ideas disclosed in this specification are not limited by the attached drawings, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and technical scope of the present invention.

[0028] Terms that include ordinal numbers, such as first, second, etc., may be used to describe various components, but the components are not limited by these terms. These terms are used solely to distinguish one component from another.

[0029] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0030] Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0031] In this application, terms such as “include” or “have” are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, but should be understood not to exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0032] Meanwhile, the display device (100) described herein is an intelligent display device (100) that adds computer support functions to, for example, a broadcast reception function. While remaining faithful to the broadcast reception function, it can be equipped with an Internet function and other functions, thereby providing a more convenient interface such as a manual input device, a touch screen, or a space remote control. In addition, it can be connected to the Internet and a computer with support for wired or wireless Internet functions, and can perform functions such as email, web browsing, banking, or games. A standardized, general-purpose operating system (OS) can be used for these various functions.

[0033] Accordingly, the display device (100) described in the present invention can perform various user-friendly functions, for example, since various applications can be freely added or deleted on a general-purpose OS kernel. More specifically, the display device (100) can be, for example, a network TV, HBB TV, smart TV, etc., and in some cases, can also be applied to a smartphone.

[0034] [Figure 1]

[0035] Figure 1 is a block diagram for explaining each configuration of a display device (100).

[0036] The display device (100) may include a communication unit (110), an input unit (120), a sensing unit (124), an output unit (150), a control unit (180), a storage unit (185), and a power supply unit (190). The configuration illustrated in FIG. 1 may include only some of the configurations, or one configuration may perform two functions.

[0037] The communication unit (110) may include a broadcast receiving unit (111) including a tuner unit and a demodulator unit. The tuner unit of the broadcast receiving unit (111) may select a broadcast signal corresponding to a channel selected by a user or all previously stored channels among broadcast signals received through an antenna or cable. The tuner unit may convert the selected broadcast signal into an intermediate frequency signal or a baseband video or audio signal.

[0038] Meanwhile, the tuner unit can sequentially select broadcast signals of all stored broadcast channels through a channel memory function among the received broadcast signals and convert them into intermediate frequency signals or baseband video or audio signals.

[0039] The demodulation unit of the broadcast receiving unit (111) can perform a demodulation operation by receiving a digital IF signal (DIF) converted by the tuner unit. The demodulation unit can output a stream signal (TS) after performing demodulation and channel decoding. At this time, the stream signal can be a signal in which a video signal, an audio signal, or a data signal is multiplexed.

[0040] The stream signal output from the demodulation unit can be input to the control unit (180). The control unit (180) can perform demultiplexing, image / audio signal processing, etc., and then output the image through the display unit (151) and output the audio through the audio output unit (152).

[0041] The external device interface unit (112) can connect an external device and a display device (100) to receive video signals, audio signals, and control signals from the external device. The interface unit (112) can be connected wired or wirelessly to external devices such as a DVD (Digital Versatile Disk), Blu-ray, game device, camera, camcorder, computer (laptop), etc.

[0042] The external device interface unit (112) transmits an image, voice, or data signal input from the outside via a connected external device to the control unit (180) of the display device (100). In addition, the image, voice, or data signal processed by the control unit (180) can be output to the connected external device.

[0043] The external device interface unit (112) may include a wired type and a wireless type. The wired type includes a physical terminal provided in the display device (100), and the wireless type may be connected to an external device through an antenna that receives a wireless signal.

[0044] The wired type may include a USB terminal, a CVBS (Composite Video Banking Sync) terminal, a component terminal, an S-video terminal (analog), a DVI (Digital Visual Interface) terminal, an HDMI (High Definition Multimedia Interface) terminal, an RGB terminal, a D-SUB terminal, etc., so as to input video and audio signals from an external device to the display device (100).

[0045] The wireless type can perform short-range wireless communication with other electronic devices located nearby. The display device (100) can be connected to a network with other electronic devices according to communication standards such as Bluetooth, RFID (Radio Frequency Identification), IrDA (Infrared Data Association), UWB (Ultra Wideband), ZigBee, and DLNA (Digital Living Network Alliance), for example.

[0046] The network interface unit (113) can access a specific web page via the connected network or another network linked to the connected network. In other words, it can access a specific web page via the network and transmit or receive data to or from the corresponding server. Additionally, it can receive content or data provided by a content provider or network operator.

[0047] That is, content such as movies, advertisements, games, VOD, and broadcast signals, as well as related information, can be received from content providers or network providers via the network. Furthermore, firmware update information and update files provided by network operators can be received. Furthermore, data can be transmitted to the Internet, content providers, or network operators.

[0048] In addition, the network interface unit (113) can select and receive a desired application from among applications open to the public through the network.

[0049] According to an embodiment, the network interface unit (113) may transmit or receive predetermined data with a user terminal connected to the display device through a network when a game application is executed on the display device. In addition, the network interface unit (113) may transmit or receive predetermined data with a server that stores game scores.

[0050] The input unit (120) may include a microphone (121) that collects sound, a user input unit (123) that detects a user's command, a sensor unit that senses the status of the display device and the surrounding conditions, and a remote signal receiving unit (125) that receives a signal from a remote control device (127).

[0051] The microphone (121) can recognize the user's voice or surrounding sounds, and in particular, receives the user's voice and processes it into electrical voice data. The microphone (121) can be implemented with various noise removal algorithms to remove noise generated during the process of receiving external audio signals.

[0052] The microphone (121) can not only collect the user's voice, convert it into voice data, and store it in the storage unit (185) or transmit it to an external device through the communication unit (110), but can also function as a user input unit (123) by analyzing the voice data and recognizing it as a user command.

[0053] The microphone (121) can be mounted on a remote control device (127) to be described later in addition to the main body of the display device (100) and transmitted to the control unit (180) through the remote signal receiving unit (125).

[0054] The user input unit (123) is a device through which a user inputs control commands to control the display device. The user input unit (123) may be configured as a keypad, button, touch pad, or touch screen.

[0055] If the user input unit (123) has a hard key button, the user can input a command related to the display device (100) by pushing the hard key button. If the user input unit (123) has a touch screen, the user can input a command related to the display device (100) using the remote control device (127) by touching the soft key of the touch screen.

[0056] In addition, the user input unit (123) may be equipped with various types of input means that can be operated by the user, such as a scroll key or a jog key, and this embodiment does not limit the scope of the present invention.

[0057] Recently, as the size of the bezel of the display device (100) has become smaller, the number of display devices (100) with a minimized user input unit (123) in the form of a physical button exposed to the outside has increased. Instead, a minimum of physical buttons are located on the back or side, and user input can be received through a remote control device (127) via a touchpad or a remote signal receiving unit (125) described later.

[0058] The remote signal receiving unit (125) can input commands related to the display device (100) through a remote control device (127) having a user input unit (123). The remote signal receiving unit (125) is a user input unit (123) and receives signals from the remote control device (127) according to various communication methods such as RF (Radio Frequency) communication method and infrared (IR) communication method, and thus may belong to a wireless communication unit.

[0059] The sensing unit (124) refers to a device that detects changes within the display device (100) or external changes. For example, it may include at least one of a proximity sensor, an illumination sensor, a touch sensor, an infrared sensor (IR sensor), an ultrasonic sensor, an optical sensor (e.g., a camera), a voice sensor (e.g., a microphone), a battery gauge, and an environmental sensor (e.g., a hygrometer, a thermometer, etc.).

[0060] Recently, display devices (100) that can move or change the direction of the display have appeared, and thus, a gyroscope sensor, an acceleration sensor, etc. may be provided to detect the attitude of the display device.

[0061] Based on the information received from the sensing unit (124), the control unit (180) can check the status of the display device (100) and, if a problem occurs, notify the user of it or control it to maintain the best status by adjusting it on its own.

[0062] In addition, the content, picture quality, size, etc. of the image provided to the display unit (151) can be controlled differently depending on the viewer detected by the sensing unit (124) or the surrounding lighting, etc., to provide an optimal viewing environment. As smart TVs advance, the functions installed in display devices are increasing, and the sensing unit (124) is also increasing along with them.

[0063] The output unit (150) is a device that provides visual and auditory information to a user through a display device, and may include a display unit (151) and an audio output unit (152).

[0064] The display unit (151) can generate a driving signal by converting a video signal, data signal, OSD signal, control signal, etc. processed by the control unit (180) or a video signal, data signal, control signal, etc. received from the interface unit. The display unit (151) can include a display panel having a plurality of pixels.

[0065] The plurality of pixels provided on the display panel may have RGB sub-pixels. Alternatively, the plurality of pixels provided on the display panel may have RGBW sub-pixels. The display unit (151) may convert image signals, data signals, OSD signals, control signals, etc. processed by the control unit (180) to generate driving signals for the plurality of pixels.

[0066] The display device (100) includes a display portion (151) that occupies most of the front surface area and a case (102) that covers the rear side of the display portion (151) and packages the display portion (151).

[0067] An LCD display panel may include a liquid crystal panel that selectively passes light through liquid crystals to implement colors corresponding to image signals for each pixel, and a backlight unit located on the back of the liquid crystal panel that supplies light to the liquid crystal panel.

[0068] The backlight unit may be a direct-type backlight unit that uses a light source directed toward the liquid crystal panel, or an edge-type unit that is composed of a light guide plate and a light source positioned laterally of the light guide plate, as illustrated in FIG. 3.

[0069] Direct-lit displays provide even illumination across the entire screen, minimizing brightness fluctuations and offering superior contrast ratio and color reproducibility. Edge-lit displays offer the advantage of having fewer light sources than direct-lit displays, resulting in lower costs and a thinner design with narrow bezels.

[0070]

[0071] The display unit may include a plurality of pixels (R, G, B). The plurality of pixels (R, G, B) may be formed in each area where a plurality of data lines and a plurality of gate lines intersect. The plurality of pixels (R, G, B) may be arranged or arranged in a matrix form.

[0072] For example, a plurality of pixels (R, G, B) may include a red (Red, hereinafter referred to as 'R') sub-pixel, a green (Green, 'G') sub-pixel, and a blue (Blue, 'B') sub-pixel. The plurality of pixels (R, G, B) may further include a white (White, hereinafter referred to as 'W') sub-pixel.

[0073] The side of the display unit (151) that displays an image may be referred to as the front or front. When the display unit (151) displays an image, the side from which the image cannot be observed may be referred to as the rear or back. Meanwhile, the display unit (151) is configured as a touch screen and can be used as an input device in addition to an output device.

[0074] The audio output unit (152) receives a signal processed by the control unit (180) and outputs it as voice.

[0075] The control unit (180) may include at least one processor, and may control the overall operation of the display device (100) using the processor included therein. Here, the processor may be a general processor such as a central processing unit (CPU). Of course, the processor may be a dedicated device such as an ASIC or another hardware-based processor.

[0076] The control unit (180) can demultiplex a stream input through a tuner unit, a demodulator unit, an external device interface unit (112), or a network interface unit (113), or process demultiplexed signals to generate and output a signal for video or audio output.

[0077] The image signal processed by the control unit (180) can be input to the display unit (151) and displayed as an image corresponding to the image signal. In addition, the image signal processed by the control unit (180) can also be input to an external output device through the external device interface unit (112).

[0078] The voice signal processed by the control unit (180) can be output as audio to the audio output unit (152). In addition, the voice signal processed by the control unit (180) can be input to an external output device through the external device interface unit (112). Although not shown in FIG. 2, the control unit (180) may include a demultiplexing unit, an image processing unit, etc. This will be described later with reference to FIG. 3.

[0079] In addition, the control unit (180) can control the overall operation within the display device (100). For example, the control unit (180) can control the tuner unit (111) to select (tune) a broadcast corresponding to a channel selected by the user or a previously stored channel.

[0080] In addition, the control unit (180) can control the display device (100) by a user command or an internal program input through the user input interface unit (173). Meanwhile, the control unit (180) can control the display unit (151) to display an image. At this time, the image displayed on the display unit (151) may be a still image or a moving image, and may be a 2D image or a 3D image.

[0081] Meanwhile, the control unit (180) can cause a predetermined 2D object to be displayed within an image displayed on the display unit (151). For example, the object can be at least one of a connected web screen (newspaper, magazine, etc.), EPG (Electronic Program Guide), various menus, widgets, icons, still images, videos, and text.

[0082] Meanwhile, the control unit (180) may modulate and / or demodulate a signal using the Amplitude Shift Keying (ASK) method. Here, the Amplitude Shift Keying (ASK) method may mean a method of modulating a signal by varying the amplitude of a carrier wave according to a data value, or of restoring an analog signal to a digital data value according to the amplitude of the carrier wave.

[0083] For example, the control unit (180) can modulate a video signal using the amplitude shift keying (ASK) method and transmit it through a wireless communication module.

[0084] For example, the control unit (180) can demodulate and process an image signal received through a wireless communication module using the amplitude shift keying (ASK) method.

[0085] Through this, the display device (100) can easily transmit and receive signals with other adjacently placed video display devices without using a unique identifier such as a MAC address (Media Access Control Address) or a complex communication protocol such as TCP / IP.

[0086] Meanwhile, the display device (100) may further include a camera unit. The camera unit can capture images of the user. The camera unit may be implemented with a single camera, but is not limited thereto, and may also be implemented with multiple cameras. Meanwhile, the camera unit may be embedded in the display device (100) above the display unit (151) or may be separately positioned. Image information captured by the camera unit may be input to the control unit (180).

[0087] The control unit (180) can recognize the user's location based on the image captured by the camera unit. For example, the control unit (180) can determine the distance (z-axis coordinate) between the user and the display device (100). In addition, the control unit (180) can determine the x-axis coordinate and y-axis coordinate within the display unit (151) corresponding to the user's location.

[0088] The control unit (180) can detect the user's gesture based on the image captured from the camera unit, or the signal detected from the sensor unit, or a combination thereof.

[0089] The storage unit (185) may store programs for each signal processing and control within the control unit (180), or may store signal-processed video, audio, or data signals. For example, the storage unit (185) may store application programs designed for the purpose of performing various tasks that can be processed by the control unit (180), and may selectively provide some of the stored application programs upon request from the control unit (180).

[0090] Programs stored in the storage unit (185) are not particularly limited as long as they can be executed by the control unit (180). The storage unit (140) may also perform a function for temporarily storing video, audio, or data signals received from an external device through the external device interface unit (112). The storage unit (185) may store information regarding a specific broadcast channel through a channel memory function such as a channel map.

[0091] Although the storage unit (185) of FIG. 1 is illustrated as being provided separately from the control unit (180), the scope of the present invention is not limited thereto, and the storage unit (185) may be included within the control unit (180).

[0092] The storage unit (185) may include at least one of volatile memory (e.g., DRAM, SRAM, SDRAM, etc.) or non-volatile memory (e.g., flash memory, hard disk drive (HDD), solid-state drive (SSD), etc.).

[0093] The power supply unit (190) can supply power to the entire display device (100). In particular, it can supply power to a control unit (180) that can be implemented in the form of a system on chip (SOC), a display unit (151) for displaying images, and an audio output unit (152) for outputting audio.

[0094] Specifically, the power supply unit (190) may be equipped with a converter (not shown) that converts AC power into DC power and a Dc / Dc converter (not shown) that converts the level of DC power.

[0095] Meanwhile, the power supply unit (190) receives power from an external source and distributes power to each component. The power supply unit (190) may utilize a method of supplying AC power by directly connecting to an external power source, or may include a power supply unit (190) that can be recharged and used, including a battery.

[0096] The former requires a wired cable connection, making movement difficult or limited. The latter offers freedom of movement, but increases weight and volume by the battery. Charging requires a direct connection to a power cable or a charging cradle (not shown) for a set period of time.

[0097] The charging cradle can be connected to the display device through an externally exposed terminal, or the built-in battery can be charged when the device is brought into proximity using a wireless method.

[0098] Meanwhile, the block diagram of the display device (100) illustrated in FIG. 1 is only a block diagram for one embodiment of the present invention, and each component of the block diagram may be integrated, added, or omitted depending on the specifications of the display device (100) actually implemented.

[0099] That is, two or more components may be combined into a single component, or a single component may be subdivided into two or more components, as needed. Furthermore, the functions performed by each block are intended to illustrate embodiments of the present invention, and their specific operations or devices do not limit the scope of the present invention.

[0100] Fig. 2 is a perspective view illustrating an example of a display device (100). (a) is a front perspective view, and (b) is a rear perspective view.

[0101] Referring to FIG. 2, the display device (100) may have a rectangular body including a pair of long sides and a pair of short sides. The display device (100) illustrated in FIG. 2 illustrates a signage-type display device (100) installed outdoors, but is not limited thereto. It may also be a display device (100) installed indoors, or a display device (100) of a small, portable type may also be included within the scope of the present invention.

[0102] Although the long side extending vertically and the short side extending horizontally are depicted in the drawing, the horizontal and vertical sides may be of equal length, and the long side may also be arranged horizontally.

[0103] For convenience of explanation, the following description is based on an example in which the side extending in the horizontal direction (x-axis direction) is the short side and the side extending in the vertical direction (y-axis direction) is the long side, but as mentioned above, the present invention is not limited thereto.

[0104] The display device (100) of the present invention may have display modules (151a, 151b) that display images on both the front and back surfaces, and images may be output independently from the display modules (151a, 151b) on the front and back surfaces. For convenience of explanation, the front and back surfaces are described, but since display modules (151a, 151b) are positioned on both sides, the surface illustrated in (b) may also be referred to as the front surface.

[0105] Since the distinction between before and after is unclear, for the sake of explanation, the direction in which the image is output is described as the outward direction and the opposite direction as the inward direction.

[0106] FIG. 3 is a cross-sectional view illustrating a conventional display device, and the display device (100) can use a display module (151a 151b) including a liquid crystal display and an edge-type backlight unit.

[0107] The light guide plate (15) may have multiple protrusions formed on the back surface to supply light incident from a light source (16) located on the side to the front surface. The back surface of the light guide plate (15) may be provided with a reflector (17) that re-reflects (①) light passing through the back surface of the light guide plate to the front surface, thereby recycling the light.

[0108] It may include an optical layer (18) including a diffusion film and a prism film that evenly disperse light on the front surface of the light guide plate (15).

[0109] The liquid crystal panel (11) is composed of a lower substrate on which thin film transistors (TFTs) and pixel electrodes are arranged, an upper substrate composed of a color filter and a common electrode for indicating color, and liquid crystals filled between these two glass substrates. Polarizing films that linearly polarize visible light (natural light) are attached to both sides of the two glass substrates. The incident polarizing film (12) located on the back and the ejection polarizing film (13) located on the front are misaligned by 90°, and depending on the arrangement of the liquid crystals, light passing through the incident polarizing film (12) on the back can selectively pass through the ejection polarizing film (13) on the front.

[0110] When voltage is applied to the gate of the TFT forming the pixel to turn on the transistor, a state is created in which an image voltage can be input to the liquid crystal display. Then, when the image voltage is applied to store image information in the liquid crystal display and the transistor is turned off, the charge stored in the liquid crystal display charger and auxiliary charger is used to display the image for a certain period of time.

[0111] When voltage is applied to the liquid crystal, the arrangement of the liquid crystal changes, and when light passes through the liquid crystal in this state, diffraction occurs. Polarized light that passes through the incident polarizing film (12) along the path guided by the liquid crystal can be diffracted and pass through the output polarizing film (13).

[0112] Since light that does not pass through the incident polarizing film (12) on the inner surface of the liquid crystal panel (11) cannot be utilized, a reflective polarizing film (14) can be additionally provided on the rear of the liquid crystal panel (11) to increase the brightness of the display module (151a, 151b).

[0113] The reflective polarizing film (14) reflects light that cannot pass through the incident polarizing film (12) and aligns it into light that can pass through the incident polarizing film (12) and passes it through (②). For example, if the incident polarizing film (12) only passes 90° polarized light, the reflective polarizing film (14) reflects 0° polarized light and passes 90° polarized light through and supplies it to the incident polarizing film (12).

[0114] For convenience of explanation, the polarization that passes through the incident polarizing film (12) is called the first polarization, and the polarization that does not pass through is called the second polarization. In the above example, the first polarization can be called the 90° polarization, and the 0° polarization can be called the second polarization.

[0115] The second polarized light reflected from the reflective polarizing film (14) is reflected from the light guide plate (15) or is re-injected into the liquid crystal panel (11) by the reflective plate. In this process, the second polarized light passes through the optical layer (16) (③). Since the optical layer (16) is manufactured by biaxially stretching a PET sheet, the polarization may be broken when the light passes through the PET sheet.

[0116] And when the light is reflected from the reflector (④), the polarization is broken and it can be re-supplied to the reflective polarizing film (14) in an unpolarized state. The reflective polarizing film (14) supplies only the first polarization of the light re-supplied in an unpolarized state to the liquid crystal panel (11).

[0117] By repeating the above process, the second polarization of the light supplied from the light source (1516) can be recycled, but there is still a limit to the loss of light.

[0118] As illustrated in FIG. 3, a double-sided display can be implemented by arranging a pair of display modules (151a, 151b) having the aforementioned light source (1516), light guide plate (15), reflector (17), diffusion film (18), reflective polarizing film (14), and liquid crystal panel (11) so that they face opposite directions and then combining them. The display device (100) of FIG. 3 has the advantage of being able to be implemented by simple combination, but the display device (100) has the problem of having a thickness that is twice that of the cross-section.

[0119] Fig. 4 is a drawing illustrating a display device (100) of the present invention. The display device (100) of the present invention can share a backlight unit between display modules (151a, 151b) on both sides and can omit a reflector required in a single-sided display device (100).

[0120] Referring to FIG. 4, the double-sided display device (100) of the present invention can supply light to two liquid crystal panels (1511a, 1511b) with a single light guide plate (1515). To provide light to both one side and the other side of the single light guide plate (1515), prism patterns can be formed on both the one side and the other side of the light guide plate (1515). For convenience of explanation, the left side of the drawing is referred to as one side of the light guide plate (1515), and the right side is referred to as the other side of the light guide plate (1515).

[0121] A light guide plate (1515) may include a first reflective polarizing film (1514a) and a first liquid crystal panel (1511a) on one side, and a second reflective polarizing film (1514b) and a second liquid crystal panel (1511b) on the other side. The first reflective polarizing film (1514a) and the second reflective polarizing film (1514b) of the present invention are characterized in that the polarizations they transmit and the polarizations they reflect are different from each other. The first reflective polarizing film (1514a) and the second reflective polarizing film (1514b) have polarization characteristics that are misaligned by 90°.

[0122] In addition, the first incident polarizing film (1512a) of the first liquid crystal panel (1511a) and the second incident polarizing film (1512a) of the second liquid crystal panel (1511b) may have different polarization characteristics. Like the first reflective polarizing film (1514a) and the second reflective polarizing film (1514b), the first incident polarizing film (1512a) and the second incident polarizing film may have polarization characteristics that are misaligned by 90°, and the first output polarizing film (1513a) of the first reflective polarizing film (1514a) and the second output polarizing film (1513b) of the second reflective polarizing film (1514b) may also have polarization characteristics that are misaligned by 90°.

[0123] Below, the optical path in a double-sided display device (100) having a configuration having polarization characteristics opposite to each other on one side and the other side will be described.

[0124] First, if we explain the path of light supplied to one side, unpolarized light (①) supplied from the light guide plate (1515) is incident on the first reflective polarizing film (1514a), and the first reflective polarizing film (1514a) allows only the first polarized light to pass through (②). The second polarized light is reflected, passes through the light guide plate (1515), and can be emitted in the direction of the other side of the light guide plate (1515) and supplied to the second reflective polarizing film (1514b).

[0125] As described above, the second reflective polarizing film (1514b) is a reflective polarizing film (1514) that transmits the second polarized light and reflects the first polarized light. Therefore, the second polarized light reflected from the first reflective polarizing film (1514a) can pass through the second reflective polarizing film (1514b) and be supplied as is to the second liquid crystal panel (1511b) (③).

[0126] The second liquid crystal panel (1511b) may have a polarization characteristic that allows the second polarization to pass through the second incident polarization film (1512b) to receive the second polarization as incident light. This has an optical characteristic opposite to that of the first incident polarization that allows the first polarization to pass through.

[0127] Light (④) supplied in the other direction of the light guide plate (1515) passes only the second polarization by the second reflective polarization film (1514b), and the first polarization is reflected (⑤). The reflected first polarization can pass through the first reflective polarization film (1514a) and be supplied to the first liquid crystal panel (1511a) (⑥). The display device (100) of the present invention can supply light reflected by the reflective polarization film (1514) on one side to the liquid crystal panel (1511a, 1511b) on the other side.

[0128] The display device (100) of FIG. 3 has a limitation in that some of the reflected light can be recycled using a reflective polarizing film (1514), but there is still a polarization component that cannot pass through. However, the display device (100) of the present invention can improve brightness by increasing the light utilization rate.

[0129] Figures 5 and 6 are drawings for explaining the path of light according to the arrangement of the light source (1516). Figure 5 is an embodiment in which the light source is positioned on both sides in the first direction (up and down direction in the drawing), and Figure 6 is an embodiment in which the light source is positioned on one side in the first direction.

[0130] The light guide plate (1515) of the present invention supplies light to both sides, and thus may include prism patterns (1515a, 1515b) on both sides. The prism pattern may include an inclined surface facing a first direction and may be configured in a shape that extends in a second direction perpendicular to the first direction and includes valleys and mountains.

[0131] Since the light guide plate (1515) of the present invention must supply light to both sides (left and right directions in the drawing), light sources (1516) can be placed on both sides of the first direction of the light guide plate (1515) as shown in FIG. 5 to secure sufficient light quantity.

[0132] The prism patterns (1515a, 1515b) formed on the light guide plate (1515) of the embodiment illustrated in Fig. 5 may have symmetrical slopes since light is supplied from both sides. However, the prism pattern (1515b) at the position furthest from the light source (1516) may be formed more densely than the prism pattern (1515a) at the position closer, so that the amount of light across the entire screen can be configured to be uniform.

[0133] As illustrated in FIG. 6, when a light source (1516) is provided only on one side, the prism patterns (1515a, 1515b) can be formed most densely on the other side (1515b) furthest from the light source (1516), and since the light source (1516) is supplied only on one side, the slopes of the prism patterns (1515a, 1515b) can be asymmetrical, as illustrated in FIG. 6.

[0134] The angle of inclination (α, the angle formed from the normal to the slope) of the slope on one side where the light source (1516) is located can be configured to be greater than 45°, and the angle of inclination (β) of the slope on the other side can be configured to be less than 45°, so that the amount of light can be configured to be uniform across the entire screen.

[0135] In order for the light reflected from the first reflective polarizing film (1514a) of the display device (100) of the present invention to pass through the second reflective polarizing film (1514b) having the opposite polarization characteristic on the other side, the polarization of the reflected light must not be broken.

[0136] The optical film (18) that breaks polarization can be omitted, and instead, as shown in FIGS. 5 and 6, an optical pattern (1514c) can be added to the reflective polarizing film (1514a, 1514b) to serve as a light collector. The optical pattern (1514c) of the reflective polarizing film (1514a, 1514b) can be a prism pattern that includes an inclined surface facing one side and the other side of the first direction where the light source is located and extends in a second direction perpendicular to the first direction. Alternatively, it can have a curved surface instead of an inclined surface, or it can have a convexly protruding hemispherical shape.

[0137] Since light is supplied uniformly from the light guide plate (1515), the optical pattern (1514c) on the reflective polarizing film (1514a, 1514b) can have a uniform density over the entire area, and the protruding shape can also be symmetrical.

[0138] As described above, the display device (100) of the present invention can implement a double-sided output display device (100) having a thin thickness.

[0139] Light efficiency can be increased by minimizing the amount of light that is lost and not reused among the light passing through the optical sheet or reflected by the reflector.

[0140] Additionally, the number of missing parts can be reduced, thereby reducing manufacturing costs.

[0141] The above detailed description should not be construed as limiting in any respect and should be considered illustrative only. The scope of the present invention should be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of the present invention are intended to be included within the scope of the present invention.

[0142] With respect to various embodiments for implementing the present invention, duplicate descriptions are omitted as they have been described above in the previous table of contents, Best Mode for Carrying Out the Invention.

[0143] Since the present invention can be applied to display devices in various fields, its industrial applicability is recognized.

Claims

1. Light guide plate; A light source located on the side of the light guide plate; A first liquid crystal panel positioned on the first surface of the light guide plate; A first reflective polarizing film positioned between the light guide plate and the first liquid crystal panel and reflecting a first direction polarization component; A second liquid crystal panel positioned on the second surface of the light guide plate; A second reflective polarizing film is positioned between the light guide plate and the second liquid crystal panel and reflects a second directional variation component, A display device characterized in that the first direction and the second direction are different from each other.

2. In paragraph 1, A display device characterized in that the first direction and the second direction are perpendicular.

3. In paragraph 2, A first incident polarizing film located on the inner surface of the first liquid crystal panel and transmitting the polarization component in the second direction; and A display device characterized by including a second incident polarizing film positioned on the inner surface of the second liquid crystal panel and transmitting the polarization component in the first direction.

4. In paragraph 3, A first polarizing film positioned on the outer surface of the first liquid crystal panel and transmitting a polarization component in the first direction; and A display device characterized by including a second polarizing film positioned on the outer surface of the second liquid crystal panel and transmitting a polarization component in the second direction.

5. In paragraph 1, A display device characterized in that the light guide plate includes prism patterns formed on both sides.

6. In paragraph 5, The above light source is located on one side of the light guide plate, A display device characterized in that the above prism pattern has a slope facing one side and a slope facing the other side at different angles.

7. In paragraph 6, The inclination angle (α) of the inclined surface on one side of the above prism pattern is greater than 45°. A display device characterized in that the inclination angle (β) of the inclined surface on the other side of the prism pattern is less than 45°.

8. In paragraph 1, The above light source is provided in pairs on one side and the other side in the first direction of the light guide plate. A display device characterized in that the prism pattern includes an inclined surface symmetrical in the first direction.

9. In paragraph 8, A display device characterized in that the prism pattern located at the center of the first direction is formed more densely than the prism pattern located adjacent to the light source.

10. In paragraph 1, A display device characterized in that the first reflective polarizing film and the second reflective polarizing film include an optical pattern formed on a surface facing the light guide plate.

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