TW200528795A - Improving image quality in an image display device - Google Patents

Abstract

A display device (50) for displaying a three dimensional image such that different views are displayed according to the viewing angle(φ), the display device including a display panel (52) having a plurality of separately addressable pixels (54) for displaying said image, the pixels being grouped such that different pixels in a group correspond to different views; a retarder (56) in optical association with the display panel, the retarder comprising retarder pixels (58), at least one retarder pixel being associated with each corresponding pixel in the display panel, wherein optical parameters of the retarder pixels (58) are varied as function of the viewing angle associated with the corresponding pixel (54) in the display panel.

Description

200528795 IX. Description of the invention: [Technical field to which the invention belongs] The present invention relates to a display device, and particularly to a display device adapted to display a three-dimensional or three-dimensional image. [Previous Technology] The generation of two-dimensional images generally requires a display device capable of providing a different field of view to the left and right eyes of the display device user. This can be done by using specially constructed goggles by directly providing a separate image to each eye of the user. In one embodiment, a display provides an alternative left-right-right field of view in a time-series manner, allowing the field of view to enter the corresponding eye of a viewer by simultaneously viewing the goggles. In contrast, the present invention relates to the type of display, in which different fields of view of an image are visible according to the viewing angle of a single display panel. Hereinafter, these will generally function as a 3D display device. However, when providing a plurality of fields of view to at least one user, it is not necessary to provide a three-dimensional image, and it is necessary to understand that the present invention is also related to a conventional multi-field display device. In another embodiment, as described in U.S. Patent No. 6,172,807, by means of a spatial modulation element in the form of an LCD panel (which instead blocks a left and right eye field of view using a parallax display) And provide timing synchronization of left and right eye sight. In order to correctly block the left and right eye sights, the system of 007 must continuously track the position of the viewer regarding the display device. In contrast, the present invention is related to the type of display, in which it is not necessary to track the position of the user, but different views of an image can be seen according to the perspective of the related display panel. In the following, generally these will function as 3D display devices. 96073.doc 200528795 之一 One of the known types of 3D display devices is a liquid crystal display, in which a parallax barrier method is implemented. Such a system is shown in FIG. Referring to FIG. 1, a display device of the parallax barrier type includes a back plate that provides a plurality of separate light sources. As shown, the back plate can be formed by a barrier layer 13 (which has a plurality of slits 14 & 14 dispersed across the surface of the surface) such as an area light source 12 (such as a light-emitting board) covered by a magic tilt mask. 11. Next, each slit 14 functions as a light source. A liquid crystal display panel (LCD) 15 includes a plurality of pixels (shown as numbers j to 10 in FIG. 1), which can be obtained by electronic signals according to conventional techniques. Separately addressed to change its individual light transmission characteristics. The back plate 11 is placed close to the LCD panel 15 to cause the line pixels 1 to 5 as shown in group 1 to correspond to the slits 14a and to facilitate the group 162 Each of the line pixels 6 to 10 shown corresponds to the slit 14b, etc. Each pixel of the pixel group 16 corresponds to a plurality of possible fields of view of an image (V-2, V-, V0, V !, V2) An interview for the individual line source 14a can be viewed through one of the pixels 1 to 5 corresponding to the field of view. The number of pixels in each group 16 (which is five in the display arrangement) can determine whether an image is presented Number of fields of view. The greater the number of fields of view, the more realistic the 3D effect will be and provide more tilt Throughout the present invention, the "images that I may consider necessary to be displayed" are all images generated by all pixels in the display panel, such as made from a plurality of "views" as determined by a specific viewing angle. A problem exists in this prior art arrangement. The light transmission coefficient of each pixel in an LCD panel is largely determined by the viewing angle. Therefore, the viewing of source 14a is 96073.doc 200528795, and the intensity will be different from the difference. Field of view. For example, v. Will be different from%. Therefore, the viewing intensity of the source will appear different from the different field of view. The driving land is used for-any feature in the image: the detected intensity of the viewed source of the component It is an important function of gray scale in it's surface image. A conventional display system will provide a driving signal to each pixel of a display panel in order to change its transmission coefficient and promote a desired gray scale to the image element. If the 3D display device 'drives each pixel with the same voltage, it should reach the gray level expected by the image element, and the resulting gray level image will be a function of a viewing angle. When the image is observed This results in sub-optimal images and unwanted grayscale artifacts at different viewing angles. [Summary of the Invention] The purpose of the present invention is to overcome or reduce unwanted grayscales in a display device for displaying three-dimensional images and Contrast artefacts, in which different viewing areas of an image are displayed according to the viewing angle. According to the first aspect of the present invention, a display device for displaying a three-dimensional image is provided, so that different viewing areas can be displayed according to the viewing angle. The display device Including: a chanting panel with a plurality of separately addressable pixels for displaying the image, the pixels are grouped so that different pixels in the group can correspond to different fields of view; a blocker, which is optically associated with the The display panel includes a plurality of retarder pixels. At least one of the retarder pixels is associated with each corresponding pixel in the display panel. The optical parameters of the retarder pixel are determined by the corresponding pixels in the display panel. .doc 200528795 The function of the associated perspective changes. According to a second aspect of the present invention, a method for displaying a three-dimensional image on a display device is provided, which includes the following steps: forming an image from a plurality of addressable pixels in a display panel, the pixels being grouped to cause Different pixels in the -group may correspond to different fields of view of the image; they are changed as a function of the angle of view associated with each pixel by the image produced by each of at least some of the pixels. With the method of the present invention, it is possible to achieve a small amount of grayscale inversion and good contrast at all viewing angles. The image quality known for an LCD panel depends greatly on the viewing angle. Especially for oblique viewing angles, artifacts appear, such as reduction of contrast and grayscale inversion. In a conventional LCD panel, all pixels are driven using a voltage between a minimum (to produce a dark complaint) and a maximum (to produce a white state), or vice versa, for image Different gray scales are generated in. This produces good results at an angle of view close to Φ-0, but the poor gray levels achieved at oblique angles are described in detail below. The "Baizhi" method of improving the viewing angle performance attempts to improve the image quality for all viewing angles at the same time. It is important because the user position of a conventional LCD display is unknown, and therefore the viewing angle of each pixel has not been observed. However, 'the inventors have confirmed that the conditions for 3D displays are different. 8. At the user's angular position for any particular field of view, because the field of view is not intended to be generated at a certain viewing angle and is not in line with other Other field of view angles related to the field of view. 96073.doc 200528795 Therefore, to improve the viewing angle performance in a 3D display, you do not need to know the position of the user previously. The point is that it is necessary to optimize the separation of the fields of view, that is, only for Viewing / designing the viewing angles in a specific field of view (as opposed to the conventional situation for all viewing angles at the same time) to optimize contrast and / or brightness. Therefore, by the method of the present invention, by (for example) pixel by pixel Based on changing the optical parameters of the pixels in the retarder, the image quality produced by each corresponding pixel in the display panel can be improved. Therefore, by the present invention The method can separate and independently improve the image quality of each viewing angle. The preferred and advantageous features of the present invention are started in the attached claims 2 to 18 and 20. [Embodiment] Referring to FIG. 1, the basics of a type of parallax barrier Among the functions, the three-dimensional image display has been described. The similar structure of the display panel 15 and the back panel 丨 i source can be used in the preferred embodiment of the present invention. However, it will be recognized that it can be used if it will become apparent in the following. Other configurations. Generally, the present invention uses a plurality of separately addressable pixels.

Preferably, the display panel is a liquid crystal display.

Each group of pixels 16 is set to receive the light from a single · a ·· 14d illumination source, a light source. This can be arranged in the manner of 96073.doc 200528795 by the area light source 12 and the mask 13 in FIG. 丨, but the pixel type 3 light source 14 of the light source 14 can also be provided by pixel column, individual pixel or pixel block. FIG. 2 shows a part of the pixel group in the display panel 15. A wide production of the 'light source] 4 will correspond to and can be viewed through the -pixel 0 ... 7 group (in a single perspective H .. this version of the-general plane with _ display panel). It will be understood that only -half 'of the pixel group 16 is displayed and the presentation-preferably seven pixels to the left of the pixel 0 is completed to complete the pixel group 16.

Each pixel has a width P0, P1,.... Preferably, the widths Po ... p are all equal 'but they can be changed in order to compensate for every extension of the angle of incidence at which light passes. The distance between the backplane illumination source 14 and the display panel 15 is shown as a dagger. In a preferred display device, h = 2.3 mm, p0 = 200 microns, and w = 50 microns (although these values can be changed significantly). Fig. 3 shows the transmission voltage and voltage (V) characteristic 30 for a 90-degree twisted nematic-type jealousy type for a display panel 15. The first curve (solid line) is the T_V characteristic for the two-view angle (eg, pixel 0). The second curve 32 (dashed line) is used for

The _v characteristic of a viewing angle φ = 50 degrees (such as pixel 5). It should be noted that when viewing-pixels at Φ = 〇, the transmission will decrease monotonically with increasing voltage (each value of v corresponds to a specific gray level). However, when one pixel is viewed at φ = 50, the D-ν curve has a different shape. At φ = 50, the image between V and grayscale is completely different 'and causes severe distortion. As indicated above, to improve the viewing angle performance of 31) displays, it is always necessary to understand the user's position. The reason is that the user in a 3D display will have previous knowledge, which represents that the pixel that produces the field of view η can be observed only at a viewing angle and not at other angles (no need to be related to other pixels but 96073.doc- 10-200528795 The important point is that the separate sights must be exhausted. The sight η is optimally only detected as φ = φη, which is completely equal to Φη). Therefore, it may be good. As can be seen in Figure 2, for example, and cannot be φ == all φ. It is still possible to use conventional methods for viewing angles in a 3D display. It is known that although all materials and methods are different when using materials and methods, it is found that the balance between the improvement values and the range of perspective must be as close as possible to achieve the improvement consistently. In 3DIXD, _- ^. 甶 了 绫 and the reason why

Official use: can benefit 'and therefore magnifies the possibility for improvement. Therefore, with the method of the present invention, it is possible to modify Wenliang for contrast and brightness in a specific field of view (at the angle of view Φ). This is achieved by changing the optical parameters of 1 and 1 pixels, and 1 as a silly comparison with the other side of the display panel. Τί is based on the function of the angle of view associated with the pixels. The father ’s good place ’each blocker ’s pixel is called Shuangyayu and —Single — Silly. # 代 地’ Each blocker pixel can be combined with a plurality of pixels on the display surface.

. In other embodiments, a plurality of retarder pixels may be incorporated in the display panel. ^ 豕 I

The blocker can be set to display ^ 4 < 谩 before the display panel, and the blocker can be separated from the display panel or connected to the display panel. · A few different parameters can be changed to improve the ratio and brightness. For example, the thickness of the blocker may vary depending on the viewing angle function associated with the pixel. In the specific display area, the direction of the guide axis ((the position of the molecule) of the pair of inductive elements in the display panel of the pair of Ina Temples. In this aspect, you can change the sound of the tilt angle, and also the tens of thousands of angle surfaces and curved surfaces. 96073.doc -11- 200528795 In other cases, the refractive index of the f-blocking pixel can be changed according to the viewing angle function of the corresponding pixel in the disk display panel. In this aspect, the blockers can be changed. Pixel birefringence. In some embodiments, at least one light parameter can be changed in at least the retarder pixel. With money, optical parameters of the retarder pixel towel are available in all materials, but in some embodiments, Different optical parameters are changed in each of the retarder pixels. The retarder pixels may include all pixels in the retarder, or instead include only a few pixels in the retarder. Reference is made to FIG. 4a '4b, 5 and 6, which will be described in detail in an embodiment of the present invention. The tilt angle of the director molecules of the blocker pixels may be determined by the viewing angle function related to the corresponding pixels in the display panel. Change: Refer to Figures 4a and 4b, showing the molecules in the direction of the guide axis The different inclination angles are shown in Fig. 4a. The inclination angles are shown in the inclined disc layer 41 of the cathode Δη material. The combination of two possible Δη material layers 42, 44 is shown in the figure. The layers 42, 44 have been Optical axis 46'48. Layer 42 is a 10-piate, such that the optical axis 46 is tilted in the same direction as the optical axis shown in Figure 4a, and layer 44 is an A-plate with a planar optical axis 48. In The illustrated single-material deceleration properties, and the layers 42 and 44 of the combination are similar (see p. Van Xin Wiu et et jpN; APPL. Phys. Vol. 39, pp. I〇i_1〇8 (2〇〇〇〇 )). Referring to FIG. 5, in an embodiment of the present invention, the tilt angle of the display pixel molecule can be changed according to the viewing angle function of the relevant pixel in the display panel. The display device 50 includes a patterned or unpatterned A liquid crystal layer 52. The liquid crystal layer includes a plurality of pixels 54. The device further includes a blocker 56 including a plurality of limiting pixels 60073.doc 200528795. The pixels 58. In the embodiment shown in FIG. The retarder pixels are combined with a corresponding pixel 54 in the display panel 52. The leading axis direction molecules in each retarder pixel 58 are changed. Bevel angle as a function of the viewing angle φ associated with the corresponding pixel 54 in the display panel 52. Figure 5 schematically shows the viewing angle φ for each pixel pixel 0, pixel 1, pixel 2, etc. As shown in FIG. 5 Therefore, it is possible to change the tilt angle of the molecules in the direction of the guide axis in the blocking piano pixel 58 on a pixel-by-pixel basis in order to improve the image quality of the 3D display. The tilt of the molecules in these blocker pixels is selected to promote polarized light. The transition of the state is greater than the lower viewing angle. This represents the combined LC layer and blocker activity in the polarized state of light passing through these layers, which will be compared with the conventional situation of homogeneous blockers More equal. This result is the transmission and voltage curve shown in Figure 3 (which is equivalent to different fields of view / view angles). This has the effect of reducing the intensity variation in different viewing angles and therefore improves the image quality at oblique viewing angles. The display device 50 further includes polarizers 70 and 72. It should be understood that the dotted rectangle does not represent the physical structure of any display device 50; the dotted rectangle is shown only for the purpose of visualization. The performance of the Hai Hai display device 50 is shown in FIG. 6. Fig. 6 shows a comparison relationship of the display panel 52 having the patterned retarder% with m dual fields of view. The solid line 60 represents a field of view in degrees, and the dashed line 62 represents-in a field of view of Φ = 60 degrees. Plot the contrast between these two angles as a function of the tilt angle of the retarder 56. It can be seen (for example) that if all retarder pixels are set to 96073.doc -13- 200528795 for all pixels, the inclination angle of the molecules in the axial direction is 40 degrees. The contrast will be 192 and 24, respectively. Then, at the viewing angles of 30 degrees and 60 degrees, the inclination angle of the retardation state can be changed on the basis of I pixels one by one by the method of the present invention. This means, for example, that the J ′ sigh is used to generate the tilt angle ⑽ of the pixel whose field of view is φ = 30 degrees. This improvement is expected to range from 192 to 273 °. Furthermore, this does not affect the contrast of any other pixels 54 used to form part of the display panel 52.

By this method, the contrast of each pixel in each pixel 54 of the display panel 52 can be improved without affecting the contrast of any other pixels. Tian's display device used to provide the results shown in FIG. 6 includes an optical stack. The optical stack has the following layers from top to bottom: a polarizer, the transmission axis is oriented at 90 degrees (the horizontal axis is defined as 0 degrees) . 270 degrees 0_plate 'tilt angle changes from 0 to 60 degrees. The deceleration of this O-piate is dAn = + l 10 nm. • 〇 Degree A-plate. The deceleration of this A-plate is dAn = + 110 nm. • Liquid crystal layer ... The molecules in the direction of the guide axis in a base substrate are 90 degrees; the molecules in the direction of the guide axis in a top substrate are 0 degrees (90 degrees rotation). The pretilt liquid crystal layer on the two substrates is 25 °. Liquid crystal material: ZLI-4792. The deceleration of the liquid crystal layer is 4Δη = :: 475 nm. • 0 degree polarizer. This means that the angle of view φ is a horizontal angle of view (the azimuth angle is always 0). This contrast is defined as the transmission in the white state (addressing the liquid crystal with a voltage of 4.5 V) divided by the transmission in the black state (driving voltage 1.5 V). FIG. 7 shows a comparison of the liquid crystal device as a function of the viewing angle for a 30 °° _piate 96073.doc -14- 200528795 tilt angle. As can be seen from FIG. 7, the image quality of a conventional LCD display with a homogeneous retarder is determined depending on the viewing angle. The curve 70 shows the horizontal viewing angle along the horizontal axis and the vertical viewing angle along the vertical axis. Both the horizontal and vertical viewing angles range from -60 degrees to +60 degrees. The dotted circle 72 indicates a 45-degree polar angle. The different areas (shown on a pseudo-color level) show contrast values, and the dashed line 74 indicates the area where the gray level inversion (gsi) has occurred. Below the main curve shown in Fig. 7, the orientations of the optical axes of various optical layers in a conventional liquid crystal display are shown schematically. [Brief description of the drawings] The present invention is described above by way of example only with reference to the accompanying drawings, in which: FIG. 1 shows a schematic cross-sectional view of the current design of an LCD device that uses a parallax barrier method to display a three-dimensional image; FIG. 2 The display can be used to illustrate the schematic structure of the parallax-obstructed LCD structure. Different types are used for φ = 〇. (Ie the normal display surface) and Bu 50. Transmission vs. voltage curve of the apparent 90 twisted nematic LCD; Figures 4a and 4b schematically illustrate the tilt of the molecules in the guide axis direction within the significant retardation benefit according to the first aspect of the invention; Viewpoint display device implementation representative diagram 'In which the tilt angle of the guide axis direction molecules in the blocker can be changed as: the viewing angle function of the corresponding pixel in the two panels is changed, the display device according to the first aspect of the present invention; ... Fig. 6 shows the relationship between the pixel contrast and the tilt angle of the retarder at two viewing angles' · 96073.doc 200528795 Fig. 7 shows the viewing angle characteristic curve for a conventional LCD display including a homogeneous retarder. [Description of main component symbols] 11 Back panel 12 Area light source 13 Mask 15 Liquid crystal display panel (LCD) 16 Pixel group 52 Display panel 54 Pixel 57 Blocker 58 Blocker pixel 70, 72 Polarizer 100 Display device 96073.doc 16-

Claims (1)

200528795 10. Scope of patent application: 1. A display device (50) for displaying images, which promotes the display of different fields of view according to the angle of view (φ). The display device includes: a display panel (52) having a display panel A plurality of separately addressable pixels of the image (54) 'the pixels are grouped to cause different pixels in a group to correspond to different fields of view; a blocker (56)' which is optically associated with the display panel, the The retarder includes a plurality of retarder pixels (58), and at least one retarder pixel is associated with each corresponding pixel in the display panel, and the optical parameters of the retarder pixels (58) correspond to the corresponding ones in the display panel. The function of the associated viewing angle of the pixel (54) changes. 2. The display device (50) as described above, wherein a blocker pixel (58) is associated with a pixel (54) in the display panel. 3. The display device (50) of claim 1, wherein a retarder pixel (58) is associated with a plurality of corresponding pixels (54) in the display panel. 4. The display device (50) according to item 1, wherein a plurality of retarder pixels (58) are associated with a single corresponding pixel (54) in the display panel. An item display device (50), wherein the blocker () 疋 is located behind the display panel. The display (56) as in any one of the preceding claims is positioned in front of the display panel. As shown in any of claims 1 to 4 96073.doc 200528795 The display device (50) of Job Seeker 1 in which the orientation of the molecules of the director axis of the blocker pixels (58) are associated with the corresponding pixels (54) in the display panel. The function of the angle of view (ψ) varies. 9. The display device (50) such as π seeking term 8, wherein the inclination angle of the retarder pixels ⑼) changes as a function of the viewing angle ⑷ associated with the corresponding pixel (54) in the display panel. 1〇 · If the display of item 8 in the month is set (50), the retarder element (called the azimuth angle according to the angle of view ⑷ associated with the corresponding pixel (54) in the display panel) 11. The display device (50) as claimed in claim 8, wherein the slopes and test surfaces of the retarder pixels are changed as a function of the viewing angle (Φ) associated with the corresponding pixels (54) in the display panel. 12. The display device (50), such as β month term, wherein the refractive index of the retarder pixels (58) changes as a function of the viewing angle ⑷ associated with the corresponding pixel (54) in the display panel. 13. The display device (50) as claimed in claim 12, wherein the retarder pixels (called birefringence are changed as a function of the angle of view ⑷ associated with the corresponding pixel (54) in the display panel. 14. If a display device (50) of M is requested, at least one optical count is changed in one or more of the retarder pixels ⑽. 15. If requested, the display is set (50). ), Where different optical parameters are changed in each of these retarder pixels ⑽. 16. As in claims 1 to 14 The display device (50) of any one, wherein the same optical parameters are changed in each of the retarder pixels (58). 96073.doc 200528795 17. The display device (50) of claim 1, # 中 此Isoblocker pixels ⑽ include all pixels in the blocker. 18. If the display of w is requested to be set (50), these blocker pixels ⑽ are included in the blocker, but not All pixels 19. A method for displaying an image on a display device (50), comprising the steps of: forming an image from a plurality of addressable pixels (M) in a -display® board (52), such The pixels are grouped to cause different pixels in the group to correspond to different views of the image; by using at least some of the pixels, each of the pixels produces an image according to the angle of view (φ) function associated with each pixel. Change 20. The method of claim 19, wherein the display device (50) further comprises: a blocker (56), which is optically associated with the display panel (52), and the block blocker includes a plurality of Retarder pixel⑽, at least one retarder pixel is associated with the display The corresponding pixels (54) in the panel; and the step of changing the image generated by each pixel in at least some of the pixels (54) in the display panel includes: depending on the corresponding pixels in the display: The function of the angle of view is used to change the optical parameters of these retarders.