KR20060116881A - Display device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, wherein the display device according to the present invention comprises a display panel for displaying an image, a light source unit for providing light to the display panel, and an incident surface facing the light source unit, and an exit surface facing the display panel. And a light guide plate having a reflection surface opposite to the emission surface and guiding light generated from the light source unit to the display panel, wherein a prism having a rounded cross-sectional shape of the protruding end is formed on the emission surface and the reflection surface, respectively. do.

Description

Display device {DISPLAY DEVICE}

1 is an exploded perspective view of a display device according to a first exemplary embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of the display device of FIG. 1 assembled along the line II-II.

3 is a graph illustrating luminance characteristics of each viewing angle of the display device according to the first exemplary embodiment.

4 is a rear perspective view of the light guide plate used in the display device according to the second exemplary embodiment of the present invention.

5 is a rear perspective view of a light guide plate used in the display device according to the third exemplary embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

10 light guide plate 11 incident surface

12: exit surface 14: reflective surface

40: display panel assembly 42: printed circuit board

44: drive IC package 50: display panel

60: top chassis 62: upper mold frame

64: bottom chassis 66: lower mold frame

70 backlight assembly 72 light source unit

74: light source cover 76: reflective sheet

The present invention relates to a display device, and more particularly, to a display device having a light guide plate having optical properties for replacing an optical sheet.

In the display device, the demand for liquid crystal displays (LCDs), which are smaller and lighter, and whose performance is further improved, has been explosively increasing, especially in the semiconductor technology, which is rapidly developing in recent years.

Liquid crystal displays have been attracting attention as an alternative means of overcoming the shortcomings of conventional cathode ray tubes (CRTs) because they have advantages such as miniaturization, light weight, and low power consumption. Currently, almost all display devices are required. It is mounted and used in an information processing device.

In general, a liquid crystal display device applies a voltage to a specific molecular array of a liquid crystal to convert it into another molecular array, and visually changes optical properties such as birefringence, photoreactivity, dichroism, and light scattering characteristics of the liquid crystal cell emitted by the molecular array. It is a light-receiving type display device which converts into a change and displays information using the modulation of the light by a liquid crystal cell.

A liquid crystal display device, which is a light receiving display device, receives light from a backlight assembly and displays an image on a display panel. The light emitted from the light source of the backlight assembly is guided through the light guide plate, and the luminance is improved through the optical sheets disposed on the light guide plate and supplied to the display panel. Optical sheets typically include a diffusion sheet, two prism sheets, a protective sheet, and the like in accordance with the light passing order. Here, the diffusion sheet collects the inclined light toward the front while passing through the light guide plate, and the prism sheet further improves the front brightness while increasing the viewing angle. Since the prism sheet is bent in the form of a mountain on its surface, a protective sheet is used to cover it, to protect it.

As such, the use of several sheets of optical sheets increases the overall manufacturing process and cost of the display device. In particular, the assembly process is complicated because a plurality of very thin optical sheets must be arranged and assembled. In addition, there is a problem that the display quality is degraded due to the flow of the optical sheets. In addition, since a plurality of optical sheets are used, light is lost while passing through the plurality of optical sheets, thereby degrading luminance of the display device.

Accordingly, an object of the present invention is to solve the above-mentioned problems, and to provide a display device having improved brightness while improving production efficiency by simplifying the overall structure without using optical sheets.

A display device according to the present invention for achieving the above object is a display panel for displaying an image, a light source unit for providing light to the display panel, and an entrance surface facing the light source unit, an exit surface facing the display panel and And a light guide plate having a reflective surface opposite to the emission surface and guiding light generated from the light source unit to the display panel, wherein a prism having a rounded cross-sectional shape of the protruding end is formed on the emission surface and the reflective surface. Each is formed.

In addition, the display device according to the present invention includes a display panel for displaying an image, a light source unit for providing light to the display panel, and an entrance surface facing the light source unit, an exit surface facing the display panel, and an opposite surface to the exit surface. The light guide plate may include a light guide plate guiding light generated from a light source unit to the display panel, and a prism may be formed on the exit surface and the reflection surface, respectively.

The prism formed on the exit surface is formed side by side in a first direction, and the prism formed on the reflective surface is formed side by side in a second direction crossing the first direction.

The first direction is a direction orthogonal to the incident surface, and the second direction is a direction parallel to the incident surface.

The prism formed on the reflective surface is preferably formed of a plurality of spaced apart prism units in the form of dots.

The light emitted to the exit surface preferably has a full width at halt maximum (FWHM) of 20 to 40 mW of the light emission characteristic curve representing the brightness of the light relative to the viewing angle.

And a protruding end portion of the prism formed on at least one of the emission surface and the reflective surface has a surface substantially parallel to the light guide plate.

Accordingly, a display device with improved luminance and improved luminance by simplifying the overall structure can be provided.

Hereinafter, a display device according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings. In the accompanying drawings, a display device using an edge type backlight assembly is schematically illustrated as an embodiment. These embodiments according to the present invention are merely for illustrating the present invention, the present invention is not limited thereto.

In addition, prior to description, in the various embodiments, components having the same configuration will be described in the first embodiment by using the same reference numerals, and in other embodiments, only the configuration different from the first embodiment will be described. Let's do it.

In order to clearly describe the present invention, parts irrelevant to the description are omitted, and like reference numerals designate like elements throughout the specification.

A first embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 1, the display device 100 according to the first exemplary embodiment includes a backlight assembly 70 for supplying light and a display panel 50 for displaying an image by using light. . The display panel is fixed on the backlight assembly 70 by using a top chassis 60. In addition, it may further include other necessary parts.

In addition, the display device 100 includes a display panel 50, driver integrated circuit packages 43 and 44, and a printed circuit board 42. The driving IC packages 43 and 44 may be formed of a chip on film (COF) or a tape carrier package (TCP). Here, the display panel 50 uses a liquid crystal display panel. This configuration is referred to as display panel assembly 40.

The display panel 50 includes a thin film transistor substrate 51 on which a plurality of thin film transistors (TFTs) are formed, a color filter substrate 53 disposed opposite to the thin film transistor substrate 51, and both substrates 51 and 53. It includes a liquid crystal (not shown) injected between). Although not shown, a polarizer is attached to the front surface of the color filter substrate 53 and the rear surface of the thin film transistor substrate 51 to linearly polarize the visible light supplied from the backlight assembly 70.

The thin film transistor substrate 51 may include a plurality of gate lines and a plurality of data lines formed in a matrix form on a transparent insulating substrate, a thin film transistor formed at an intersection of the gate line and the data line, and electrically connected to the thin film transistor. And a pixel electrode made of transparent indium tin oxide (ITO). The thin film transistor has a source terminal connected to a data line, a gate terminal connected to a gate line, and a drain terminal connected to a pixel electrode.

Accordingly, the driving signal supplied from the printed circuit board 42 is transmitted to the gate line and the data line of the display panel 50 and input to the source terminal and the gate terminal of the thin film transistor. The electrical signal required for pixel formation is turned on or off to switch the pixel electrode connected to the drain terminal.

On the other hand, the color filter substrate 53 is disposed on the thin film transistor substrate 51. The color filter substrate 53 is a substrate on which pixels of three primary colors (red, green and blue, or cyan, magenta, and yellow), which are color pixels in which a predetermined color is expressed while light passes, are formed and are generally transparent like ITO over the entire surface. A common electrode made of a material is formed. When the thin film transistor, which is a switching element, is turned on, an electric field is formed between the pixel electrode and the common electrode. The arrangement angle of the liquid crystal injected between the thin film transistor substrate 51 and the color filter substrate 53 is changed by such an electric field, and thus a desired image is obtained by the changed light transmittance.

In order to control the arrangement angle of the liquid crystals and the timing of the arrangement of the liquid crystals, the gate lines and the data lines of the thin film transistor substrate 51 receive driving signals and timing signals from the printed circuit board 42 through the driving IC packages 43 and 44, respectively. It is authorized.

The backlight assembly 70 receives light emitted from the light source unit 72 that emits light, the light source cover 74 that surrounds the light source unit 72, and protects the light source unit 72, and receives the light emitted from the light source unit 72. The light guide plate 10 which guides to the panel 50, and the reflection sheet 76 which is located under the light guide plate 10 and reflects light are provided. Although a lamp is shown as the light source unit 72 in FIG. 1, this is merely to exemplify a light source according to the present invention, but the present invention is not limited thereto. Accordingly, a light emitting diode (LED) may be used as the light source unit 72, and another light source in the form of a surface light source or a linear light source may be used. Although not shown in FIG. 1, an inverter circuit board and a control circuit board for supplying power are provided on the bottom of the bottom chassis 64. The inverter circuit board converts an external power supply to a constant voltage level and supplies it to the light source unit 72, and the control circuit board is connected to the above-described printed circuit board 42 to convert the analog drive signal into a digital drive signal and display the display panel ( To 50).

In addition, the backlight assembly 70 includes a bottom chassis 64 that houses a light source unit 72, a light source cover 74, a light guide plate 10, a reflector plate 76, and the like. In addition, the backlight assembly 70 has an upper mold frame 62 and a lower mold frame 66 to fix the upper and lower portions thereof, respectively.

The bent printed circuit board 42 covered with the top chassis 60 is fixedly supported on the bottom chassis 64.

As shown in FIG. 1, the display device 100 according to the first exemplary embodiment of the present invention does not include optical sheets, and has the display panel 50 interposed with an upper mold frame 62 disposed at an edge thereof. And the light guide plate 10 directly face each other. Thus, since the light passing through the light guide plate 10 is directly supplied to the display panel 50 without passing through other media, the loss of light can be minimized, and ultimately, the luminance can be improved. In addition, since the optical sheets are not provided, the assembly process of the display device 100 can be further simplified.

The light guide plate 10 has an entrance face 11 facing the light source unit 72, an exit face 12 facing the display panel 50, and a reflection face 14 that is opposite to the exit face 12. . As shown in the enlarged circle of FIG. 1, the exit surface 12 and the reflective surface 14 have prism patterns 121 and 141 formed in a round shape in the cross-sectional shape of the protruding end.

The prism 121 formed on the exit surface 12 is formed side by side in the first direction (Y-axis direction), and the prism 141 formed on the reflective surface 14 is in the second direction (X-axis direction) that intersects the first direction. Are formed side by side. Here, the first direction is a direction orthogonal to the incident surface 11, and the second direction is a direction parallel to the incident surface 11.

The prism 121 formed on the emission surface 12 of the light guide plate 10 plays the same role as the prism sheet, which is one of the optical sheets included in the conventional display device. That is, the prism 121 formed on the emission surface 12 is supplied from the light source unit 72 so that light incident on the incident surface 11 of the light guide plate 10 is emitted from the emission surface 12 of the light guide plate 10. In this case, the light emitted vertically from the exit surface 12 is collected to further improve the front luminance. Accordingly, the display device 100 having a clear screen can be implemented.

The prism 141 formed on the reflective surface 14 of the light guide plate 10 reflects light toward the exit surface 12 and simultaneously emits light 121 of the light guide plate 10 in the light guide plate 10 along the second direction. The light is emitted vertically.

As described above, the light guide plate 10 again emits light vertically emitted by the prism 121 formed along the second direction on the reflective surface 12, and then another prism 141 formed along the first direction on the emission surface 14. Light is emitted to the display panel 50. According to such a structure, the display quality of the display device 100 can be improved.

In the prisms 121 and 141, the total reflection angle of the light supplied from the light source unit 72 and incident on the incident surface 11 of the light guide plate 10 is maintained at 42 s to 45 s so that the reflection angle is 43 s. Light incident on 10 is emitted vertically. A path through which light is emitted from the light guide plate 10 having such prisms 121 and 141 will be described below with reference to FIG. 2.

FIG. 2 is a partial cross-sectional view of the display device 100 of FIG. 1 assembled and taken along the line II-II. The path of light emitted from the light source unit 72 entering the light guide plate 10 is indicated by an arrow. . Since the prism 141 (shown in FIG. 1) is finely formed on the surface of the light guide plate 10, the illustration is omitted in FIG. 2 for convenience.

A reflective sheet 76 is disposed below the light guide plate 10 to reflect light emitted from the light source unit 72 and directed toward the bottom of the light guide plate 10 to the upper part of the light guide plate 10. With the reflective sheet 76, some of the light is totally reflected as indicated by the arrows in FIG. 2 due to the prisms formed on the reflective surface 14 of the light guide plate 10, and the remaining light is perpendicular to the upper surface of the light guide plate 10. Outgoing. As described above, the light directed vertically to the upper part of the light guide plate 10 is collected by the prism formed on the exit surface 12 of the light guide plate 10 and supplied to the display panel 50.

As shown in FIG. 2, since the light guide plate 10 directly faces the display panel 50, light having improved luminance may be supplied to the display panel 50 without additional light loss. In particular, it is not necessary to assemble several sheets of optical sheets separately due to the removal of the optical sheets, thereby simplifying the assembly process.

In this embodiment, the prism has a round cross-sectional shape of the protruding end portion, which further improves the light emission characteristics. That is, since the prism is formed in a round shape, it is possible to improve the viewing angle by further improving the luminance characteristic of light for each viewing angle while improving the luminance.

3 illustrates light emission characteristics of the light guide plate 10 according to the present invention, that is, luminance characteristics of light with respect to a viewing angle of the display device 100. As shown in FIG. 3, it is most efficient that the full width at halt maximum (FWHM) of the light emission characteristic curve representing the luminance characteristic of the light relative to the viewing angle is 20 kV to 40 kV. That is, when the half-angle angle is more than 40 Hz, it may have uniform luminance for each viewing angle, and thus the viewing angle problem of the display device 100 may be significantly improved. However, the luminance of the front surface of the display panel 50 is relatively reduced. On the other hand, when the half-angle angle is less than 20 Hz, the front luminance is high, but the viewing angle is considerably poor.

In addition, by adjusting the surface roughness of the emission surface 12 and the reflective surface 14 of the light guide plate 10 can be adjusted so that the half-value angle of the light emission characteristic curve is between 20 ° to 40 °. As the surface roughness of the exit surface 12 and the reflecting surface 14 decreases, the luminance at the front surface, that is, the luminance at the viewing angle of 0 Hz is increased.

Although not shown, a protective film may be coated on the exit surface 12 and the reflective surface 14 of the light guide plate 10 to prevent damage to the protruding prism. That is, the protective film plays the same role as the protective sheet belonging to the optical sheet. The protective film may be made of a resin, for example, polymethylmethacrylate (PMMA). A protective film made of such a material can be manufactured to efficiently protect the prism.

A second embodiment of the present invention will be described with reference to FIG. 4 shows a back state of the light guide plate 10. The light guide plate 10 is coupled to the light source unit 72 to receive light therefrom.

As shown in FIG. 4, in the light guide plate 10 according to the present exemplary embodiment, a plurality of prisms 141 formed on the reflective surface 14 form a prism unit 142. The prism units 142 are spaced apart from each other in a dot form. As the distance from the light source unit 72 increases, the amount of light emitted from the light source unit 72 and traveling in the second direction (-Y axis direction) decreases, so that the prism unit 142 is moved away from the light source unit 72. The more densely formed, the light is reflected to the exit surface 12 of the light guide plate 10 as much as possible.

As such, when the prism 141 is formed of the dot-shaped prism unit 142, not only the appearance quality defects such as the bright line generated by the light, the light leakage in the diagonal direction, the dark part, etc. can be improved, but the light is controlled. There is an advantage that the brightness uniformity is improved.

The enlarged circle of FIG. 4 shows the specific shape of the prism unit 142 in detail. The enlarged circle of FIG. 4 shows a cross section of the prism unit 142 taken along the line AA, and the machining of the prism unit 142 forms a semicircular protrusion on the reflective surface 14 of the light guide plate 10. It is possible by processing the prism 141 in a round shape. Here, the specific processing method will be easily understood by those skilled in the art to which the present invention pertains, and thus the detailed description thereof will be omitted.

According to the formation of the prism 141, the light re-incident to the reflecting surface 14 of the light guide plate 10 can be uniformly diffused in the horizontal direction, and the luminance is improved by being perpendicular to the emitting surface 12.

A third embodiment of the present invention will be described with reference to FIG. 5. 5 shows the rear surface of the light guide plate 10.

As shown in FIG. 5, the light guide plate 10 according to the third embodiment of the present invention has three or more protruding ends of the prisms 221 and 241 formed on the emission surface 12 and the reflective surface 14. It is formed to have. The plurality of prisms 241 formed on the reflecting surface 14 forms a prism unit 242. The prism units 242 are spaced apart from each other in a dot form.

In FIG. 5, detailed shapes of the prism unit 242 in the form of dots formed on the reflection surface 14 and the prism 221 formed on the emission surface 12 are shown in detail. In this embodiment, the protruding ends of the prisms 221 and 241 are formed to have four angles.

As such, even when the protruding ends of the prisms 221 and 241 are formed to have three or more angles, the emission characteristics of the light emitted from the exit surface 12 of the light guide plate 10 may be improved. At this time, it is more advantageous to improve the emission characteristics that the protruding end portions 221a and 241a of the at least one prism are formed flat among the prisms 221 and 241 respectively formed on the emission surface 12 and the reflective surface 14.

As described above, in the case of the present invention, the brightness of light can be increased as well as the light can be easily collected and the viewing angle can be improved, compared to the prior art, thereby improving the display quality of the display device.

Although the present invention has been described above, it will be readily understood by those skilled in the art that various modifications and variations are possible without departing from the spirit and scope of the claims set out below.

As described above, in the display device according to the present invention, since the light guide plate directly faces the display panel and a plurality of prisms are formed on the upper surface of the light guide plate, the light is emitted vertically from the upper part of the light guide plate, so that the viewing angle is improved and the light loss is improved. The brightness can be improved by minimizing the

In addition, since the optical sheet does not need to be used, the assembly process of the display device can be simplified to improve production efficiency.

Claims (7)

Display panel for displaying images, A light source unit providing light to the display panel; A light guide plate for guiding the light generated by the light source unit to the display panel having an incident surface facing the light source unit, an exit surface facing the display panel, and a reflective surface opposite to the exit surface. Including; A prism having a round cross-sectional shape of the protruding end formed on the emission surface and the reflective surface, respectively. Display panel for displaying images, A light source unit providing light to the display panel; A light guide plate for guiding the light generated by the light source unit to the display panel having an incident surface facing the light source unit, an exit surface facing the display panel, and a reflective surface opposite to the exit surface. Including; And a prism having protruding ends having three or more angles, respectively, on the exit surface and the reflection surface. The method according to claim 1 or 2, The prism formed on the exit surface is formed side by side in a first direction, and the prism formed on the reflective surface is formed side by side in a second direction crossing the first direction. The method of claim 3, The first direction is a direction orthogonal to the incident surface, and the second direction is a direction parallel to the incident surface. The method according to claim 1 or 2, The prism formed on the reflective surface is formed of a plurality of spaced apart prism units in the form of dots. The method according to claim 1 or 2, The light emitted from the exit surface has a full width at halt maximum (FWHM) of 20 to 40 kHz in a light emission characteristic curve representing luminance of light relative to a viewing angle. The method of claim 2, And a protruding end portion of the prism formed on at least one of the emission surface and the reflective surface has a surface substantially parallel to the light guide plate.

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