See-through display

Abstract

A see-through display comprises: a display panel having a plurality of pixels; and a driving circuit for applying a voltage corresponding to input grayscale data to the plurality of pixels, wherein the display panel comprises: a first substrate having pixel electrodes; a second substrate; a liquid crystal layer sandwiched between the first and second substrates; a first polarizer disposed on the first substrate and having a first polarization axis; and a second polarizer disposed on the second substrate and having a second polarization axis. When the transmittance of the pixel when a minimum voltage is applied to the pixel from the driving circuit is set to TW, and the transmittance of the pixel when a maximum voltage is applied to the pixel from the driving circuit is set to TB, the display panel has a normally white characteristic satisfying the relationship TW>TB.

Description

Technical Field

[0001] The present invention relates to a see-through display and a liquid crystal display. Background Art

[0002] Patent Document 1 discloses a see-through display having a display panel configured to be transparent through a background. The see-through display disclosed in Patent Document 1 includes a panel light source that illuminates the display panel with multiple colors in a time-division manner.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2015 / 190461 Summary of the Invention

[0006] However, the see-through display disclosed in Patent Document 1 has a problem in that the background of the display panel appears blurred in the transparent display state.

[0007] A see-through display according to one embodiment of the present invention provides a see-through display capable of suppressing the background of a display panel from appearing blurred.

[0008] Solutions for solving problems

[0009] (1) One embodiment of the present invention relates to a see-through display comprising: a display panel having a plurality of pixels; and a driving circuit for applying a voltage corresponding to input grayscale data to the plurality of pixels, the display panel comprising: a first substrate having pixel electrodes; a second substrate; a liquid crystal layer sandwiched between the first substrate and the second substrate; a first polarizer disposed on the first substrate and having a first polarization axis; and a second polarizer disposed on the second substrate and having a second polarization axis, wherein the display panel has a normally white characteristic satisfying the relationship TW>TB when a minimum voltage is applied to the pixel from the driving circuit, the transmittance of the pixel is TW, and when a maximum voltage is applied to the pixel from the driving circuit, the transmittance of the pixel is TB.

[0010] (2) A see-through display according to another aspect of the present invention has the configuration of the see-through display according to the aspect (1) above, wherein the second polarization axis is parallel to the first polarization axis.

[0011] (3) Another aspect of the present invention relates to a see-through display that can be configured as follows: in the configuration of the see-through display according to the above-mentioned (1) or (2), regarding the normally white characteristic of the display panel, when the axis parallel to the axis rotating the first polarization axis by 45 degrees in the clockwise direction is set as the a-axis, the axis parallel to the axis rotating the first polarization axis by 45 degrees in the counterclockwise direction is set as the b-axis, the a-axis component of the refractive index of the liquid crystal layer is set as na, the b-axis component is set as nb, and the value representing the difference between the refractive index of the a-axis component and the refractive index of the b-axis component, that is, the refractive index anisotropy of the liquid crystal layer is set as △n=|na-nb|, the value of △n when the voltage applied to the plurality of pixels by the driving circuit is below a threshold voltage is smaller than △n when the voltage applied by the driving circuit is greater than the threshold voltage, and the threshold voltage represents the boundary of whether the orientation of the liquid crystal molecules in the liquid crystal layer is changed.

[0012] (4) The see-through display according to another embodiment of the present invention may be configured as follows: in the configuration of the see-through display according to the above-mentioned embodiment (1) or (2), regarding the normally white characteristic of the display panel, when the axis parallel to the axis rotating the first polarization axis by 45 degrees in the clockwise direction is set as the a-axis, the axis parallel to the axis rotating the first polarization axis by 45 degrees in the counterclockwise direction is set as the b-axis, the a-axis component of the refractive index of the liquid crystal layer is set as na, the b-axis component is set as nb, the value representing the difference between the refractive index of the a-axis component and the refractive index of the b-axis component, that is, the refractive index anisotropy of the liquid crystal layer is set as △n=|na-nb|, the thickness of the liquid crystal layer is set as d, and the phase difference of the liquid crystal layer is set as d△n, the value of d△n when the voltage applied to the plurality of pixels by the driving circuit is below a threshold voltage is below 50 nm, and the threshold voltage represents the boundary of whether the orientation of the liquid crystal molecules in the liquid crystal layer is changed.

[0013] (5) The see-through display according to other embodiments of the present invention may also be configured as follows: in the configuration of the see-through display according to the above-mentioned embodiment (3) or (4), the liquid crystal layer includes liquid crystal molecules having a negative dielectric anisotropy, and when the voltage applied to the plurality of pixels by the driving circuit is below the threshold voltage, the liquid crystal molecules are oriented in a direction perpendicular to the long axis of the liquid crystal molecules relative to the in-plane direction of the liquid crystal layer.

[0014] (6) The see-through display according to another embodiment of the present invention may also be configured as follows: in the configuration of the see-through display according to any one of the above embodiments (3) to (5), the liquid crystal layer includes liquid crystal molecules, and when the voltage applied to the plurality of pixels by the driving circuit is below the threshold voltage, the liquid crystal molecules are oriented in a direction in which the long axis of the liquid crystal molecules is parallel to the in-plane direction of the liquid crystal layer and parallel to or perpendicular to the first polarization axis.

[0015] (7) The see-through display according to another embodiment of the present invention may also be configured as follows: in the configuration of the see-through display according to any one of the embodiments (1) to (6), each of the plurality of pixels includes a red sub-pixel, a green sub-pixel, and a blue sub-pixel, and the display panel has a color filter, the color filter including: a red transmittance filter film that transmits light corresponding to the wavelength band of the red sub-pixel; a green transmittance filter film that transmits light corresponding to the wavelength band of the green sub-pixel; and a blue transmittance filter film that transmits light corresponding to the wavelength band of the blue sub-pixel. The red transmission filter, the green transmission filter, and the blue transmission filter are configured to transmit light corresponding to a wavelength band thereof, and in a voltage-brightness characteristic representing a correlation between the brightness of light respectively transmitted through the red transmission filter, the green transmission filter, and the blue transmission filter and the voltage applied to the plurality of pixels, the cell thicknesses of the liquid crystal layers respectively corresponding to the red transmission filter, the green transmission filter, and the blue transmission filter are set in such a manner that a minimum brightness value within a range of voltages applied to the plurality of pixels by the driving circuit becomes less than 5 times the minimum brightness value in the voltage-brightness characteristic.

[0016] (8) The see-through display according to another embodiment of the present invention may also be configured as follows: in the configuration of the see-through display according to any one of the above embodiments (1) to (6), each of the plurality of pixels includes a red sub-pixel, a green sub-pixel, and a blue sub-pixel, and the display panel has a color filter, the color filter including: a red transmittance filter film that transmits light corresponding to the wavelength band of the red sub-pixel; a green transmittance filter film that transmits light corresponding to the wavelength band of the green sub-pixel; and a blue transmittance filter film that transmits light corresponding to the wavelength band of the blue sub-pixel, the thickness of the red transmittance filter film being thinner than the thickness of each of the blue transmittance filter film and the green transmittance filter film, and the difference between the thickness of the green transmittance filter film and the thickness of the blue transmittance filter film being less than half of the difference between the thickness of the red transmittance filter film and the thickness of the blue transmittance filter film.

[0017] (9) A see-through display according to another embodiment of the present invention may also be configured as follows: in the configuration of the see-through display according to any one of the above-mentioned embodiments (1) to (6), each of the plurality of pixels includes a red sub-pixel, a green sub-pixel, and a blue sub-pixel, and the display panel has a color filter including: a red transmittance filter film that transmits light corresponding to the wavelength band of the red sub-pixel; a green transmittance filter film that transmits light corresponding to the wavelength band of the green sub-pixel; and a blue transmittance filter film that transmits light corresponding to the wavelength band of the blue sub-pixel, the unit thickness of the liquid crystal layer corresponding to the red transmittance filter film is thicker than the unit thickness of the liquid crystal layer corresponding to the blue transmittance filter film and the green transmittance filter film, respectively, and the difference between the unit thickness of the liquid crystal layer corresponding to the green transmittance filter film and the unit thickness of the liquid crystal layer corresponding to the blue transmittance filter film is less than half of the difference between the unit thickness of the liquid crystal layer corresponding to the red transmittance filter film and the unit thickness of the liquid crystal layer corresponding to the blue transmittance filter film.

[0018] (10) The see-through display according to another embodiment of the present invention may also be configured as follows: in the configuration of the see-through display according to any one of the above embodiments (1) to (6), each of the plurality of pixels includes a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a white sub-pixel, and the display panel has a color filter, which includes: a red transmittance filter film that transmits light corresponding to the wavelength band of the red sub-pixel; a green transmittance filter film that transmits light corresponding to the wavelength band of the green sub-pixel; a blue transmittance filter film that transmits light corresponding to the wavelength band of the blue sub-pixel; and a white transmittance filter film that transmits light corresponding to the white sub-pixel, and in each of the pixels, the ratio of the area occupied by the white sub-pixel to the area occupied by the red sub-pixel, the green sub-pixel, and the blue sub-pixel is in the range of greater than 0.5 and less than 1.5.

[0019] (11) The see-through display according to another embodiment of the present invention may also be configured as follows: in the configuration of the see-through display according to the embodiment (10) above, in each pixel, when the areas of the red sub-pixels, the green sub-pixels, the blue sub-pixels, and the white sub-pixels are equal, the ratio of the number of the white sub-pixels to the total number of the red sub-pixels, the green sub-pixels, and the blue sub-pixels is in the range of greater than 2 / 3 and less than 3 / 3.

[0020] (12) The see-through display according to another embodiment of the present invention may also be configured as follows: in the configuration of the see-through display according to the above-mentioned embodiment (10) or (11), the pixels are arranged in the order of the red sub-pixel, the green sub-pixel, and the blue sub-pixel, or in the order of the red sub-pixel, the blue sub-pixel, and the green sub-pixel, and the white sub-pixel is inserted between each of the red sub-pixel, the green sub-pixel, and the blue sub-pixel, or between each of the red sub-pixel, the blue sub-pixel, and the green sub-pixel.

[0021] (13) The see-through display according to another embodiment of the present invention may also be configured as follows: in the configuration of the see-through display according to the embodiment (12), in each pixel, when a group of adjacent sub-pixels is set as a sub-pixel pair, the driving circuit applies voltages of different polarities to the adjacent sub-pixel pairs, and applies a voltage that reverses the polarity of each sub-pixel pair per frame.

[0022] (14) A see-through display according to another embodiment of the present invention may be configured as follows: in the configuration of the see-through display according to any one of the embodiments (1) to (13) above, the minimum value of the grayscale data is set to L_min, the maximum value is set to L_max, and any values ​​of the grayscale data are set to L_a, L_b, and L_c, and when the relationship L_min<L_a<L_b<L_c<L_max is satisfied, the brightness of the display panel corresponding to L_min, L_a, L_b, L_c, and L_max, respectively, is set to Y_min, Y_a, Y_b, Y_c, and Y_max, respectively, and L_b and Y_b satisfy Y=L_min which represents the grayscale brightness characteristic of the display panel serving as a reference. γ When γ satisfies γ=log((Y_b-Y_min)÷(Y_max-Y_min))÷log((L_b-L_min)÷(L_max-L_min)), the driving circuit applies the voltage to the display panel so as to satisfy Y_a<((L_a-L_min)÷(L_max-L_min)) γ , Y_c>((L_c-L_min)÷(L_max-L_min)) γ relationship.

[0023] (15) One embodiment of the present invention relates to a liquid crystal display having a display panel and a driving circuit, wherein the display panel has a plurality of pixels and includes: a first substrate having pixel electrodes; a second substrate; a liquid crystal layer sandwiched between the first substrate and the second substrate; a first polarizing plate disposed on the first substrate and having a first polarizing axis; a second polarizing plate disposed on the second substrate and having a second polarizing axis; a phase difference film disposed at least between the liquid crystal layer and the first polarizing plate or between the liquid crystal layer and the second polarizing plate, wherein the driving circuit applies a voltage corresponding to input grayscale data to the plurality of pixels, and when the voltage is applied to the plurality of pixels in accordance with the grayscale data of the first polarizing plate, the first polarizing plate is connected to the first polarizing plate. When the axis parallel to the axis rotated 45 degrees in the clockwise direction of the polarization axis is set as the a-axis, and the axis parallel to the axis rotated 45 degrees in the counterclockwise direction of the first polarization axis is set as the b-axis, the axial direction of the slow axis of the phase difference film is consistent with the axial direction of the a-axis or the b-axis, the phase difference of light passing through the phase difference film is less than 50nm, the slow axis of the liquid crystal layer is consistent with the axial direction of the a-axis or the b-axis, and when the voltage applied to the multiple pixels by the driving circuit is less than the threshold voltage, the phase difference of light passing through the liquid crystal layer is less than 50nm, and the threshold voltage indicates the boundary of whether the orientation of the liquid crystal molecules in the liquid crystal layer is changed.

[0024] (16) The liquid crystal display involved in other aspects of the present invention may also be constructed as follows: in the structure of the liquid crystal display involved in the above-mentioned aspect (15), the liquid crystal layer contains liquid crystal molecules with negative dielectric constant anisotropy, and when the voltage applied to the plurality of pixels by the driving circuit is below the threshold voltage, the liquid crystal molecules are oriented in a direction perpendicular to the long axis of the liquid crystal molecules relative to the in-plane direction of the liquid crystal layer.

[0025] (17) The liquid crystal display involved in other aspects of the present invention may also be constructed as follows: in the structure of the liquid crystal display involved in the above-mentioned aspect (15) or (16), each pixel in the plurality of pixels includes a red sub-pixel, a green sub-pixel and a blue sub-pixel, and the display panel has a color filter, which includes: a red transmission filter film that allows light corresponding to the wavelength band of the red sub-pixel to pass through; a green transmission filter film that allows light corresponding to the wavelength band of the green sub-pixel to pass through; and a blue transmission filter film that allows light corresponding to the wavelength band of the blue sub-pixel to pass through. The red transmission filter, the green transmission filter, and the blue transmission filter are configured to transmit light corresponding to a wavelength band thereof, and in a voltage-brightness characteristic representing a correlation between the brightness of light respectively transmitted through the red transmission filter, the green transmission filter, and the blue transmission filter and the voltage applied to the plurality of pixels, the cell thicknesses of the liquid crystal layers respectively corresponding to the red transmission filter, the green transmission filter, and the blue transmission filter are set in such a manner that a minimum brightness value within a range of voltages applied to the plurality of pixels by the driving circuit becomes less than 5 times the minimum brightness value in the voltage-brightness characteristic.

[0026] (18) The liquid crystal display involved in other aspects of the present invention may also be constructed as follows: in the structure of the liquid crystal display involved in the above-mentioned (15) or (16) aspect, each pixel of the plurality of pixels includes a red sub-pixel, a green sub-pixel and a blue sub-pixel, and the display panel has a color filter, which includes: a red transmittance filter film, which allows light corresponding to the wavelength band of the red sub-pixel to pass through; a green transmittance filter film, which allows light corresponding to the wavelength band of the green sub-pixel to pass through; and a blue transmittance filter film, which allows light corresponding to the wavelength band of the blue sub-pixel to pass through, the thickness of the red transmittance filter film is thinner than the thickness of each of the blue transmittance filter film and the green transmittance filter film, and the difference between the thickness of the green transmittance filter film and the thickness of the blue transmittance filter film is less than half of the difference between the thickness of the red transmittance filter film and the thickness of the blue transmittance filter film.

[0027] (19) The liquid crystal display according to another embodiment of the present invention may also be configured as follows: in the configuration of the liquid crystal display according to the above-mentioned embodiment (15) or (16), each of the plurality of pixels constituting an image displayed by the display panel includes a red sub-pixel, a green sub-pixel, and a blue sub-pixel, and the display panel has a color filter, the color filter including: a red transmittance filter film that transmits light corresponding to the wavelength band of the red sub-pixel; a green transmittance filter film that transmits light corresponding to the wavelength band of the green sub-pixel; and a blue transmittance filter film that transmits light corresponding to the wavelength band of the green sub-pixel; a light filter film that transmits light corresponding to a wavelength band of the blue sub-pixel, wherein a cell thickness of the liquid crystal layer corresponding to the red transmission filter film is thicker than a cell thickness of the liquid crystal layer corresponding to the blue transmission filter film and the green transmission filter film, respectively, and a difference between a cell thickness of the liquid crystal layer corresponding to the green transmission filter film and a cell thickness of the liquid crystal layer corresponding to the blue transmission filter film is less than half a difference between a cell thickness of the liquid crystal layer corresponding to the red transmission filter film and a cell thickness of the liquid crystal layer corresponding to the blue transmission filter film.

[0028] (20) The liquid crystal display involved in other aspects of the present invention may also be constructed as follows: in the structure of the liquid crystal display involved in the above-mentioned (15) or (16) aspect, each pixel of the plurality of pixels includes a red sub-pixel, a green sub-pixel, a blue sub-pixel and a white sub-pixel, and the display panel has a color filter, which includes: a red transmittance filter film, which allows light corresponding to the wavelength band of the red sub-pixel to pass through; a green transmittance filter film, which allows light corresponding to the wavelength band of the green sub-pixel to pass through; a blue transmittance filter film, which allows light corresponding to the wavelength band of the blue sub-pixel to pass through; and a white transmittance filter film, which allows light corresponding to the white sub-pixel to pass through, and in each of the pixels, the ratio of the area occupied by the white sub-pixel to the area occupied by the red sub-pixel, the green sub-pixel and the blue sub-pixel is in the range of greater than 0.5 and less than 1.5.

[0029] (21) The liquid crystal display involved in other aspects of the present invention may also be constructed as follows: in the structure of the liquid crystal display involved in the above-mentioned (20) aspect, in each of the pixels, when the areas of the red sub-pixels, the green sub-pixels, the blue sub-pixels and the white sub-pixels are equal, the ratio of the number of the white sub-pixels to the total number of the red sub-pixels, the green sub-pixels and the blue sub-pixels is in the range of greater than 2 / 3 and less than 3 / 3.

[0030] (22) The liquid crystal display involved in other embodiments of the present invention may also be constructed as follows: in the configuration of the liquid crystal display involved in the above-mentioned embodiment (20) or (21), in each of the pixels, the red sub-pixels, the green sub-pixels and the blue sub-pixels are arranged in the order of the red sub-pixels, the green sub-pixels and the blue sub-pixels, or in the order of the red sub-pixels, the blue sub-pixels and the green sub-pixels, and the white sub-pixels are inserted between each of the red sub-pixels, the green sub-pixels and the blue sub-pixels, or between each of the red sub-pixels, the blue sub-pixels and the green sub-pixels.

[0031] (23) The liquid crystal display involved in other aspects of the present invention may also be constructed as follows: in the structure of the liquid crystal display involved in any one of the aspects (15) to (22) above, the minimum value of the grayscale data is set to L_min, the maximum value is set to L_max, and any value of the grayscale data is set to L_a, L_b, L_c, and when the relationship L_min<L_a<L_b<L_c<L_max is satisfied, the brightness of the display panel corresponding to L_min, L_a, L_b, L_c, L_max is set to Y_min, Y_a, Y_b, Y_c, Y_max respectively, and L_b and Y_b satisfy Y=L which represents the grayscale brightness characteristic of the display panel serving as a reference. γ When γ satisfies γ=log((Y_b-Y_min)÷(Y_max-Y_min))÷log((L_b-L_min)÷(L_max-L_min)), the driving circuit applies the voltage to the plurality of pixels so as to satisfy Y_a<((L_a-L_min)÷(L_max-L_min)) γ , Y_c>((L_c-L_min)÷(L_max-L_min)) γ relationship. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a diagram showing a schematic configuration of a see-through display according to the first embodiment of the present invention.

[0033] Figure 2 This is a block diagram showing an example of the configuration of a main part of a see-through display according to the first embodiment of the present invention.

[0034] Figure 3 Yes Figure 2 FIG. 1 is a graph showing the relationship between the voltage applied to a display panel and the transmittance of the display panel in a see-through display.

[0035] Figure 4 Yes Figure 2The graph shows the relationship between the voltage applied to the display panel by the driving circuit unit included in the see-through display and the grayscale that can be expressed on the display panel.

[0036] Figure 5 It is a perspective view schematically showing the configuration of a main part of a display panel according to the first embodiment of the present invention.

[0037] Figure 6 It is schematically represented Figure 5 A perspective view showing an example of a light transmission state of the display panel shown.

[0038] Figure 7 It is schematically represented Figure 5 The diagram shows the alignment state of a plurality of liquid crystal molecules corresponding to one pixel when the applied voltage in the display panel is equal to or lower than the threshold voltage.

[0039] Figure 8 It is schematically represented Figure 5 FIG. 1 is a diagram showing the alignment state of a plurality of liquid crystal molecules corresponding to one pixel when a voltage greater than a threshold voltage is applied to the display panel shown.

[0040] Figure 9 It is schematically represented Figure 5 The diagram shows the alignment state of multiple liquid crystal molecules in the IPS mode when the applied voltage in the display panel is lower than the threshold voltage.

[0041] Figure 10 It is schematically represented Figure 5 The diagram shows the alignment state of multiple liquid crystal molecules in the display panel under the IPS mode when the applied voltage is greater than the threshold voltage.

[0042] Figure 11 It is schematically represented Figure 5 The diagram shows the alignment state of multiple liquid crystal molecules in the IPS mode when the applied voltage in the display panel is lower than the threshold voltage.

[0043] Figure 12 It is schematically represented Figure 5 The diagram shows the alignment state of multiple liquid crystal molecules in the display panel under the IPS mode when the applied voltage is greater than the threshold voltage.

[0044] Figure 13 It is schematically represented Figure 5 FIG. 1 is a diagram showing the alignment state of a plurality of liquid crystal molecules in the FFS mode when the applied voltage in the display panel is equal to or lower than the threshold voltage.

[0045] Figure 14 It is schematically represented Figure 5The diagram shows the alignment state of multiple liquid crystal molecules in the FFS mode when the applied voltage is greater than the threshold voltage in the display panel.

[0046] Figure 15 It is schematically represented Figure 5 FIG. 1 is a diagram showing the alignment state of a plurality of liquid crystal molecules in the FFS mode when the applied voltage in the display panel is equal to or lower than the threshold voltage.

[0047] Figure 16 It is schematically represented Figure 5 The diagram shows the alignment state of multiple liquid crystal molecules in the FFS mode when the applied voltage is greater than the threshold voltage in the display panel.

[0048] Figure 17 It is a cross-sectional view schematically showing the configuration of a liquid crystal layer and a color filter included in a display panel according to a comparative example of the first embodiment of the present invention.

[0049] Figure 18 It is shown together with the use Figure 17 The graph shown is a correlation between the luminance values ​​of each of R wavelength light, G wavelength light, and B wavelength light and the voltage when a voltage is applied to the liquid crystal layer by the color filter.

[0050] Figure 19 This is a cross-sectional view schematically showing the configuration of a liquid crystal layer and a color filter included in a display panel according to a first modification of the first embodiment of the present invention.

[0051] Figure 20 This is a cross-sectional view schematically showing the configuration of a liquid crystal layer and a color filter included in a display panel according to a first modification of the first embodiment of the present invention.

[0052] Figure 21 This is a graph showing the correlation between the luminance values ​​of each of R wavelength light, G wavelength light, and B wavelength light and the voltage when the drive circuit unit controls the display panel time voltage according to the first modification of the first embodiment of the present invention.

[0053] Figure 22 It is a perspective view schematically showing the configuration of a main part of a display panel according to a second modification of the first embodiment of the present invention.

[0054] Figure 23 This is a diagram schematically showing an example of an arrangement pattern of sub-pixels constituting each pixel of a display panel according to a second modification of the first embodiment of the present invention.

[0055] Figure 24This is a diagram schematically showing an example of an arrangement pattern of sub-pixels constituting each pixel of a display panel according to a second modification of the first embodiment of the present invention.

[0056] Figure 25 This is a diagram showing an example of the correspondence between the arrangement pattern of sub-pixels and the polarity of each sub-pixel constituting each pixel of a display panel according to a comparative example of the first embodiment of the present invention.

[0057] Figure 26 This is a diagram showing an example of the correspondence between the sub-pixel arrangement pattern and the polarity of each sub-pixel in a display panel according to the second modification of the first embodiment of the present invention.

[0058] Figure 27 This is a graph showing grayscale luminance characteristics of a display panel according to a third modified example of the first embodiment of the present invention.

[0059] Figure 28 It is a perspective view showing an example of a liquid crystal display according to a second embodiment of the present invention.

[0060] Figure 29 Yes Figure 28 A block diagram showing an example of the main structure of a liquid crystal display.

[0061] Figure 30 Schematically Figure 28 A perspective view showing the main structure of a display panel included in the liquid crystal display.

[0062] Figure 31 This is a perspective view schematically showing an example of a light transmission state of a display panel included in a liquid crystal display according to a modified example of the second embodiment of the present invention. DETAILED DESCRIPTION

[0063] Hereinafter, embodiments and modifications of the present invention will be described with reference to the accompanying drawings. Furthermore, identical or equivalent elements will be denoted by the same reference numerals throughout the accompanying drawings, and repeated descriptions thereof will be omitted. Furthermore, the embodiments and modifications described below are merely examples of the present invention, and the present invention is not limited to the embodiments and modifications. In addition to these embodiments and modifications, various changes may be made based on design, etc., as long as they do not depart from the technical concept of the present invention.

[0064] (First embodiment)

[0065] Reference Figure 1 A see-through display 100 according to a first embodiment of the present invention will be described. Figure 1 1 is a diagram showing a schematic configuration of a see-through display 100 according to a first embodiment of the present invention. Figure 1 , a schematic configuration of the see-through display 100 when viewed from the side is schematically shown.

[0066] The see-through display 100 is a display system capable of seeing through the back side of the display panel 1. The see-through display 100 can also display information (images) displayed on the display panel 1 by overlapping the background on the back side of the display panel 1. Therefore, the see-through display 100 is preferably used in, for example, display cases and display windows.

[0067] The see-through display 100 includes: a box-shaped housing 4 for housing an exhibit 5; a display panel 1, which is a transmissive liquid crystal panel, disposed on one side of the housing 4; a drive circuit unit 6 (drive circuit); a protective plate 2 disposed on the front side of the display panel 1 and covering the panel surface of the display panel 1; and an illumination unit 3 disposed within the housing 4. The side on which the illumination unit 3 is disposed relative to the display panel 1 is referred to as the rear side, and the opposite side is referred to as the front side.

[0068] The display panel 1 can be in an image display state in which an image is displayed on the panel surface, or in a transparent display state in which the background on the back side of the display panel 1 is seen through the display panel 1. In the image display state, a viewer on the front side of the display panel 1 can view the image displayed on the panel surface of the display panel 1. On the other hand, in the transparent display state, the viewer can view the background on the back side of the display panel 1, that is, the background inside the housing 4. In addition, the display panel 1 is configured to switch between the image display state and the transparent display state on a pixel-by-pixel basis. Therefore, an image can be displayed in a portion of the panel surface of the display panel 1, and the background inside the housing 4 can be seen through the remaining area of ​​the panel surface.

[0069] The detailed structure of the display panel 1 will be described later.

[0070] The driver circuit unit 6 applies voltages corresponding to grayscale data input from the outside to the pixels of the display panel 1 to drive the display panel 1. The display panel 1 can perform display control based on the magnitude of the voltages applied from the driver circuit unit 6 to the pixels.

[0071] The protective plate 2 is a plate member for protecting the display panel 1 , and can be formed of a transparent glass plate member or an acrylic plate member having light transmissivity.

[0072] The lighting unit 3 emits light including visible light, and for example, a white LED (light emitting diode) that emits white light can be used. Figure 1As shown, the lighting unit 3 is disposed in a corner of the side surface where the display panel 1 is provided in the housing 4. The light emitted from the lighting unit 3 can illuminate the exhibit 5 disposed in the housing 4. The lighting unit 3 can also function as a light source for displaying images on the display panel 1.

[0073] Furthermore, in the see-through display 100, the illumination unit 3 is configured to serve as both a light source for illuminating the exhibit 5 and a light source for causing the display panel 1 to display an image. However, a configuration may also include separate illumination units that function as a light source for illuminating the exhibit 5 and a light source for displaying an image on the display panel 1. In such a configuration, the illumination unit that functions as a light source for displaying an image on the display panel 1 is disposed within the housing 4 so as to not obstruct viewing of the exhibit 5 and to be able to emit light toward the display panel 1.

[0074] The display panel 1 includes a color filter 12 (see Figure 5 ), the color filter 12 includes: a red transparent filter film 20 (refer to the following Figure 5 ), which transmits light corresponding to the wavelength band of the red sub-pixel; a green transmission filter film 21 (see Figure 5 ), which transmits light corresponding to the wavelength band of the green sub-pixel; and a blue transmittance filter film 22 (see Figure 5 ), which transmits light corresponding to the wavelength band of the blue sub-pixel. Furthermore, the light emitted from the illumination unit 3 passes through the color filter 12, and color display is performed by synthesizing the three colors of red, green, and blue.

[0075] In addition, in order to see through the exhibit 5 on the back side of the display panel 1, the display panel 1 is configured such that a polarizing plate 14 (see the following) located on the back side of the display panel 1 is provided. Figure 5 ) is not provided on the outside of the housing 4, or a transparent component is provided so that the exhibit 5 can be viewed from the front side of the display panel 1. The required transparency of the see-through display 100 is defined as, for example, the transmittance of light that passes through the display panel 1 from within the housing 4 and is output to the outside. In other words, the transmittance of light throughout the see-through display 100. Specifically, the required transparency of the see-through display 100, when expressed as light transmittance, is within a range of 2% to 50%, preferably 20%.

[0076] Next, refer to Figure 2 —4. A configuration related to driving the display panel 1 in the see-through display 100 according to the first embodiment of the present invention will be described. Figure 2 This is a block diagram showing an example of the configuration of main parts of the see-through display 100 according to the first embodiment of the present invention. Figure 3 Yes Figure 2FIG. 1 is a graph showing the relationship between the voltage applied to the display panel 1 and the transmittance of the display panel 1 of the see-through display 100 shown in FIG. Figure 3 In FIG, the vertical axis represents the transmittance of light passing through each of the plurality of pixels of the display panel 1, and the horizontal axis represents the value of the voltage applied to each of the plurality of pixels of the display panel 1. Figure 4 Yes Figure 2 The graph of the relationship between the voltage applied to the display panel 1 by the driving circuit unit 6 of the see-through display 100 shown in FIG. and the grayscale that can be expressed on the display panel 1 is shown in FIG. Figure 4 In FIG. 1 , the vertical axis shows an example of a voltage value applied to each pixel of the display panel 1, and the horizontal axis shows the number of grayscales that can be expressed on the display panel 1. The display panel 1 can handle 1024 grayscale levels for each of the R, G, and B colors.

[0077] That is, the display panel 1 has a plurality of pixels, and a first electrode 31 (pixel electrode) and a TFT 35 are provided corresponding to each pixel. In addition, a second electrode 32 (in the position opposite to the first electrode 31) is provided. Figure 2 (not shown in the figure). Furthermore, the display panel 1 can perform grayscale control on a pixel-by-pixel basis by switching the input signal to the first electrode 31 on and off using the TFT 35.

[0078] Specifically, in the display panel 1, grayscale data (e.g., any grayscale value between 0 and 1024) from the driver circuit unit 6 is input to the source driver 60 via the TCON substrate 61. Based on the input grayscale data, the source driver 60 applies a voltage within the range of the drive voltage for the display panel 1 to the source electrode of the TFT 35 via the source bus 37. Furthermore, the gate driver 70 applies a Hi voltage to the gate electrode of the TFT 35 via the gate bus 36. When the Hi voltage is applied to the gate electrode by the gate driver 70, the TFT 35 turns on, and a source signal is supplied from the source driver 60 to the first electrode 31. Thus, in the display panel 1, the driver circuit unit 6 performs grayscale control on a pixel-by-pixel basis.

[0079] And, as Figure 3 As shown, in the see-through display 100, the voltage range that can be applied from the driver circuit unit 6 to the display panel 1 is 0.5V-7.5V. The threshold voltage indicating whether the orientation of the liquid crystal molecules in the liquid crystal layer 10 changes is 2.0V. In practice, the driving voltage range applied from the driver circuit unit 6 to each pixel to drive the display panel 1 is greater than 2.0V, for example, in the range of approximately 2.2V to 7.5V. Figure 3 As shown, the transmittance when the minimum voltage is applied to the pixel within the driving voltage range is TW, and the transmittance when the maximum voltage is applied to the pixel is TB. Moreover, TW and TB have a so-called normally white characteristic that satisfies the relationship TW>TB.

[0080] In addition, if Figure 4 As shown in one example, the driving circuit section 6 controls the voltage for each grayscale within the driving voltage range so that the grayscale brightness characteristics of the display panel become predetermined grayscale brightness characteristics described later.

[0081] However, in the transparent display state, if light is scattered when passing through the display panel 1, the viewer may see the exhibit 5 arranged in the housing 4 in a blurred state. Therefore, in the see-through display 100 of the first embodiment, in order to suppress the background on the back side of the display panel 1 from appearing blurred, the display panel 1 has the following configuration.

[0082] (Display Panel Configuration)

[0083] Reference Figure 5 as well as Figure 6 , the detailed structure of the display panel 1 is described below. Figure 5 It is a perspective view schematically showing the configuration of a main part of the display panel 1 according to the first embodiment of the present invention. Figure 6 It is schematically represented Figure 5 A perspective view showing an example of a light transmission state of the display panel 1 shown.

[0084] like Figure 5 As shown, the display panel 1 includes first and second electrodes 31 and 32 , a color filter 12 , a pair of glass substrates 13 (a first glass substrate 13 a and a second glass substrate 13 b ), and a pair of polarizers 14 (a first polarizer 14 a and a second polarizer 14 b ).

[0085] The polarizing plate 14 includes a first polarizing plate 14 a disposed on one side (the back side) of the liquid crystal layer 10 and having a first polarization axis A; and a second polarizing plate 14 b disposed on the other side (the front side) of the liquid crystal layer 10 and having a second polarization axis B parallel to the first polarization axis A. Specifically, the first polarizing plate 14 a and the second polarizing plate 14 b are arranged in parallel Nicols.

[0086] Here, “parallel” not only means that the first polarization axis A and the second polarization axis B are geometrically parallel, but also includes that the first polarization axis A and the second polarization axis B are substantially parallel within the range of the design error of the display panel 1 .

[0087] The glass substrate 13 is a transparent substrate with insulating properties. The glass substrate 13 includes: a first glass substrate 13a (first substrate) disposed between the liquid crystal layer 10 and the first polarizing plate 14a; and a second glass substrate 13b (second substrate) disposed between the liquid crystal layer 10 and the second polarizing plate 14b. Specifically, the liquid crystal layer 10 is sandwiched between the first glass substrate 13a and the second glass substrate 13b. A first electrode 31 and a second electrode 32 are provided on the surfaces of the first glass substrate 13a and the second glass substrate 13b facing the liquid crystal layer 10. The first electrode 31 and the second electrode 32 can be formed of a transparent conductive material such as ITO (indium tin oxide). Furthermore, a thin film for controlling the orientation of the liquid crystal molecules, i.e., an alignment film (not shown), is provided on the first glass substrate 13a and the second glass substrate 13b. The alignment film is subjected to an alignment treatment to align the liquid crystal molecules 10a in a predetermined direction (pretilt direction). Examples of the alignment treatment applied to the alignment film include a rubbing treatment and a photo-alignment treatment.

[0088] In the see-through display 100 of the first embodiment, as described above, the display panel 1 has a parallel Nicol arrangement in which the polarization axes of the opposing first polarizer 14 a and second polarizer 14 b are parallel to each other.

[0089] In addition, if Figure 3 As shown, the see-through display 100 has a normally white characteristic as described below. Specifically, when the voltage applied from the drive circuit unit 6 to the liquid crystal layer 10 of the display panel 1 (hereinafter referred to as the applied voltage) reaches the minimum voltage within the drive voltage range, the light transmittance is the highest (transmittance TW). Furthermore, when this transmittance reaches TW, it is referred to as a transparent display state. Conversely, when the applied voltage reaches the maximum voltage within the drive voltage range, the light transmittance of the see-through display 100 is the lowest (transmittance TB). When this transmittance reaches TB, it is referred to as an image display state.

[0090] The normally white characteristic described above can be defined, for example, by the following configuration of the display panel 1. First, let the axis parallel to the axis rotated 45 degrees clockwise about the first polarization axis A be the a-axis, and the axis parallel to the axis rotated 45 degrees counterclockwise about the first polarization axis A be the b-axis. Let the a-axis component of the refractive index of the liquid crystal layer 10 be na, and the b-axis component be nb. The difference between the a-axis and b-axis refractive indices, representing the refractive index anisotropy of the liquid crystal layer 10, be Δn = |na - nb|.

[0091] Under the above-mentioned conditions, the Δn value when the applied voltage of the display panel 1 is below the threshold voltage is smaller than the Δn value when the applied voltage is above the threshold voltage. Specifically, the Δn value when the applied voltage of the display panel 1 is below the threshold voltage is approximately 0, for example, less than 0.02.

[0092] Here, in a parallel Nicol configuration, when incident light forms a plane wave along the a-axis and the b-axis, the transmittance of the liquid crystal layer 10 changes significantly. Furthermore, the following relationship holds: as the transmittance of the liquid crystal layer 10 approaches 100%, the value of Δn approaches 0. Conversely, as the transmittance decreases, the value of Δn increases.

[0093] When the applied voltage to the display panel 1 is equal to or lower than the threshold voltage, Δn becomes smaller than when the applied voltage is greater than the threshold voltage, and Δn becomes approximately zero.

[0094] Furthermore, the display panel 1 may be defined as having a normally white characteristic as follows: That is, based on the above-set conditions, the thickness of the liquid crystal layer 10 is d, and the phase difference of the liquid crystal layer 10 is dΔn.

[0095] Here, the following relationship holds: when the transmittance of the liquid crystal layer 10 is close to 100%, the phase difference (d△n) of light passing through the liquid crystal layer 10 is close to 0. Conversely, if the transmittance of the liquid crystal layer 10 decreases, the phase difference (d△n) of light passing through the liquid crystal layer 10 becomes larger.

[0096] In the display panel 1 , when the applied voltage is below the threshold voltage, dΔn is 50 nm or less, preferably 0 nm. Therefore, it can be said that the display panel 1 has a normally white characteristic in which the transmittance increases when the applied voltage is below the threshold voltage.

[0097] Therefore, in the see-through display 100 of the first embodiment, when the voltage applied to the display panel 1 is below the threshold voltage, birefringence and scattering of light transmitted through the liquid crystal layer 10 can be suppressed. Consequently, when the see-through display 100 is in a transparent display state, the background behind the display panel 1 can be prevented from appearing blurred. Furthermore, when the viewer is viewing only the background of the see-through display 100, the driver circuit unit 6 applies only the minimum voltage within the drive voltage range to the display panel 1, thereby reducing power consumption.

[0098] However, in the see-through display 100 of the first embodiment, the display panel 1 is driven in the VA (Vertical Alignment) mode. A pixel electrode serving as the first electrode 31 is provided on the first glass substrate 13a, and a common electrode serving as the second electrode 32 is provided on the second glass substrate 13b. An electric field is applied from the first glass substrate 13a toward the second glass substrate 13b perpendicular to the principal surface of the liquid crystal layer 10. Furthermore, when the applied voltage is below the threshold voltage, the display panel 1 maintains a uniform alignment of the liquid crystal molecules 10a.

[0099] Specifically, in the display panel 1, the liquid crystal layer 10 includes liquid crystal molecules 10a (negative liquid crystal molecules) having negative dielectric constant anisotropy. That is, the liquid crystal layer 10 uses negative nematic liquid crystals. When the applied voltage is below the threshold voltage, as shown in FIG. Figure 7 As shown, the plurality of liquid crystal molecules 10a are aligned so that their long axis directions are perpendicular to the in-plane direction of the liquid crystal layer 10. Figure 7 It is schematically represented Figure 5 The diagram shows the alignment state of a plurality of liquid crystal molecules 10a corresponding to one pixel when the applied voltage in the display panel 1 is lower than the threshold voltage. Figure 7 , the alignment state of the liquid crystal molecules 10 a when viewed from a direction perpendicular to the main surface of the liquid crystal layer 10 is shown.

[0100] On the other hand, when the applied voltage is greater than the threshold voltage, as Figure 8 As shown, the plurality of liquid crystal molecules 10 a are aligned in a direction in which the major axis is substantially parallel to the in-plane direction of the liquid crystal layer 10 . Figure 8 It is schematically represented Figure 5 FIG. 1 is a diagram showing the alignment state of a plurality of liquid crystal molecules 10a corresponding to one pixel when a voltage greater than a threshold voltage is applied to the display panel 1 shown in FIG. Figure 8 In, with Figure 7 Similarly, the alignment state of the liquid crystal molecules 10a when viewed from a direction perpendicular to the main surface of the liquid crystal layer 10 is shown. Figure 8 As well as the above Figure 7 In FIG. 1 , for ease of explanation, the liquid crystal molecule 10 a is shown in a cone shape, with the long axis direction of the liquid crystal molecule 10 a being the height direction of the cone.

[0101] And, in Figure 7 and Figure 8 In the VA mode, the MVA (Multi-domain Vertical Alignment) mode is shown as an example, in which a pixel is divided into four domains. Specifically, in the MVA mode, the alignment state of the liquid crystal molecules 10a in the liquid crystal layer 10 can be made different within each of the four regions that divide a pixel. By varying the alignment state of the liquid crystal molecules 10a for each of the four regions, the display panel 1 can expand the viewing angle of the display panel 1.

[0102] In the display panel 1, when the applied voltage is below the threshold voltage, the alignment of the plurality of liquid crystal molecules 10a becomes uniform. Consequently, the refractive index in the liquid crystal layer 10 also becomes uniform. Furthermore, light incident perpendicularly to the panel surface of the display panel 1 passes through the display panel 1 with little refraction.

[0103] Therefore, when the voltage applied to the liquid crystal layer 10 is equal to or lower than the threshold voltage, and a viewer views the exhibit 5 on the back side of the display panel 1 , blurring of the exhibit 5 can be suppressed.

[0104] Furthermore, the above description describes the display panel 1 as being driven in a VA mode, but the present invention is not limited thereto. For example, the display panel 1 may be driven in an IPS (In Plane Switching) mode. Figures 9 to 12 As shown, when the driving mode is IPS mode, the display panel 1 is provided with a first electrode 31 (pixel electrode) serving as a pixel electrode and a second electrode 32 (opposing electrode) serving as a common electrode on the first glass substrate 13a, and an electric field is applied parallel to the in-plane direction of the first glass substrate 13a. Figure 9 and Figure 11 It is schematically represented Figure 5 The diagram shows the alignment state of a plurality of liquid crystal molecules 10 a in the display panel 1 in the IPS mode when the applied voltage is equal to or lower than the threshold voltage. Figure 10 and Figure 12 It is schematically represented Figure 5 The diagram shows the alignment state of a plurality of liquid crystal molecules 10 a in the display panel 1 in the IPS mode when an applied voltage greater than a threshold voltage is applied. Figures 9 to 12 , the alignment state of the plurality of liquid crystal molecules 10 a when viewed in a direction perpendicular to the main surface of the liquid crystal layer 10 is shown. Figures 9 to 12 In the figure, for the sake of convenience, the liquid crystal molecule 10a is shown as an ellipse. Also, the long axis direction of the liquid crystal molecule 10a is the long axis direction of the ellipse. Figures 9 to 12 In FIG. 1 , the first electrode 31 provided on the first glass substrate 13a is schematically shown by a double-dashed line, and the second electrode 32 is schematically shown by a single-dashed line. Figures 9 to 12 As shown, the first electrode 31 is arranged to extend vertically in the center, and the second electrode 32 is arranged in a U-shape to surround the first electrode 31 .

[0105] exist Figure 9 、 Figure 10 , the alignment state of the plurality of liquid crystal molecules 10a in the case of positive liquid crystal is shown. That is, when the applied voltage is below the threshold voltage, the plurality of liquid crystal molecules 10a are aligned parallel to the in-plane direction of the liquid crystal layer 10 and with the long axis approximately perpendicular to the first polarization axis A. Figure 9 As shown in FIG. 1 , the plurality of liquid crystal molecules 10a are uniformly aligned with their major axes oriented in the vertical direction of the paper. Figure 10 As shown, the long axes of the liquid crystal molecules 10 a arranged between the first electrode 31 and the second electrode 32 are tilted in the left-right direction on the paper.

[0106] also, Figure 11 、 Figure 12 The figure shows the alignment state of the plurality of liquid crystal molecules 10a when the liquid crystal layer 10 is a negative liquid crystal. That is, when the applied voltage is below the threshold voltage, the plurality of liquid crystal molecules 10a are aligned parallel to the in-plane direction of the liquid crystal layer 10 and with the long axis substantially parallel to the first polarization axis A. Figure 11 As shown in FIG, the plurality of liquid crystal molecules 10a are uniformly aligned with their respective long axes oriented in the left-right direction. Figure 12 As shown, the long axes of the liquid crystal molecules 10 a arranged between the first electrode 31 and the second electrode 32 are tilted in the vertical direction.

[0107] Thus, when the applied voltage is below the threshold voltage, the electric field has no effect on the liquid crystal molecules 10a. Consequently, the liquid crystal molecules 10a maintain their initial alignment and are uniformly aligned. Consequently, the refractive index in the liquid crystal layer 10 is uniform. Furthermore, light incident perpendicularly to the panel surface of the display panel 1 is substantially unrefracted and passes through the display panel 1. Therefore, when the applied voltage to the liquid crystal layer 10 is below the threshold voltage, blurring of the displayed object 5 on the back side of the display panel 1 can be suppressed.

[0108] The display panel 1 may be driven in another mode that is a variation of the IPS mode. For example, the display panel 1 may be driven in an FFS (Fringe-Field Switching) mode. Figures 13 to 16 As shown, when the driving mode is the FFS mode, the display panel 1 has a full-surface electrode 33 disposed on the first glass substrate 13a, and an insulating layer (not shown) disposed on the full-surface electrode 33. In addition, data electrodes 34 are disposed on the insulating layer. Figure 13 and Figure 15 It is schematically represented Figure 5 The diagram shows the alignment state of a plurality of liquid crystal molecules 10 a in the FFS mode when the applied voltage in the display panel 1 is lower than the threshold voltage. Figure 14 and Figure 16 It is schematically represented Figure 5 FIG. 1 shows an alignment state of a plurality of liquid crystal molecules 10 a in the display panel 1 in the FFS mode when an applied voltage greater than a threshold voltage is applied. Figures 13 to 16 , the alignment state of the plurality of liquid crystal molecules 10 a when viewed from a direction perpendicular to the main surface of the liquid crystal layer 10 is shown. Figures 13 to 16 In the figure, for the sake of convenience, the liquid crystal molecule 10a is shown as an ellipse. Also, the long axis direction of the liquid crystal molecule 10a is the long axis direction of the ellipse. Figures 13 to 16In FIG. 1 , the entire surface electrode 33 provided on the first glass substrate 13a is schematically shown by hatching, and the data electrode 34 is schematically shown by a single dot-dashed line. Figures 13 to 16 As shown, a plurality of data electrodes 34 ( Figures 13 to 16 The three data electrodes 34 are arranged in a V shape on the entire surface electrode 33.

[0109] In FFS mode, as in IPS mode, an electric field is applied parallel to the in-plane direction of the first glass substrate 13a. However, because the voltage is applied from the data electrodes 34 to the solid-surface electrodes 33 via the insulating layer, no voltage is applied to the liquid crystal molecules 10a located on the data electrodes 34. Therefore, even if a voltage exceeding the threshold voltage is applied to the liquid crystal layer 10, the liquid crystal molecules 10a located on the data electrodes 34 do not change.

[0110] Figure 13 、 Figure 14 , the alignment state of the plurality of liquid crystal molecules 10a is shown when the liquid crystal layer 10 is a positive liquid crystal. That is, when the applied voltage is below the threshold voltage, the plurality of liquid crystal molecules 10a are aligned parallel to the in-plane direction of the liquid crystal layer 10 and with the long axis approximately perpendicular to the first polarization axis A. Figure 13 As shown in FIG. 1 , a plurality of liquid crystal molecules 10a are uniformly aligned with their major axes oriented in the vertical direction. Furthermore, when a voltage greater than the threshold voltage is applied, as shown in FIG. Figure 14 As shown, the alignment state of the liquid crystal molecules 10 a located on the data electrodes 34 does not change, and the long axes of the liquid crystal molecules 10 a located between different data electrodes 34 are tilted in the left-right direction.

[0111] also, Figure 15 、 Figure 16 The figure shows the alignment state of the plurality of liquid crystal molecules 10a when the liquid crystal layer 10 is a negative liquid crystal. That is, when the applied voltage is below the threshold voltage, the plurality of liquid crystal molecules 10a are aligned parallel to the in-plane direction of the liquid crystal layer 10 and with the long axis substantially parallel to the first polarization axis A. Figure 15 As shown in FIG. 1 , the plurality of liquid crystal molecules 10a are uniformly aligned with their major axes oriented in the left-right direction. Furthermore, when a voltage greater than the threshold voltage is applied, as shown in FIG. Figure 16 As shown, the alignment state of the liquid crystal molecules 10 a located on the data electrodes 34 does not change, but the long axes of the liquid crystal molecules 10 a located between different data electrodes 34 are tilted in the vertical direction.

[0112] Thus, when the applied voltage is below the threshold voltage, the electric field has no effect on the liquid crystal molecules 10a. Consequently, the alignment of the plurality of liquid crystal molecules 10a remains uniform, maintaining their initial alignment. Consequently, the refractive index in the liquid crystal layer 10 becomes uniform. Furthermore, light incident perpendicularly to the panel surface of the display panel 1 passes through the display panel 1 with little refraction.

[0113] As described above, in the see-through display 100 of the first embodiment, the display panel 1 has a structure having a normally white characteristic in which the transmittance is highest when the applied voltage is equal to or lower than the threshold voltage.

[0114] Therefore, in the see-through display 100 of the first embodiment, when the applied voltage of the display panel 1 is equal to or lower than the threshold voltage, it is possible to suppress the light transmitted through the liquid crystal layer 10 from being birefringent and scattered.

[0115] Thus, the see-through display 100 according to the first embodiment can suppress the background on the back side of the display panel 1 from appearing blurred when in the transparent display state.

[0116] Furthermore, when the viewer is allowed to see only the background of the see-through display 100 , power consumption due to application of voltage can be reduced.

[0117] [First Modification]

[0118] Next, the structure of a see-through display 100 according to a first variation of the first embodiment of the present invention will be described. The see-through display 100 according to the first variation of the first embodiment further enhances the contrast ratio of the see-through display 100 according to the first embodiment. The see-through display 100 according to the first variation of the first embodiment is identical to the see-through display 100 according to the first embodiment, except that the structure of the display panel 1 is improved to enhance the contrast ratio. Therefore, identical components are denoted by identical reference numerals, and their descriptions are omitted.

[0119] In the display panel 1 according to the first embodiment, the first polarizer 14a and the second polarizer 14b are arranged in parallel Nicols. Furthermore, the display panel 1 has a normally white characteristic, where the transmittance reaches its maximum when the applied voltage is below a threshold voltage, resulting in a white display. Thus, compared to a display panel with a normally black characteristic, the display panel 1 with the normally white characteristic does not decrease in brightness when displaying black while displaying an image, but has a lower contrast ratio. For example, while the contrast ratio of the former is approximately 4000, the contrast ratio of the latter is approximately 10.

[0120] When the display panel 1 has a normally white characteristic, the contrast ratio decreases because light passing through the liquid crystal layer 10 displays black while exhibiting birefringence. To display black while light passing through the liquid crystal layer 10 displays birefringence, the following mathematical formula (1) must be satisfied, assuming the retardation of the display panel 1 is Re (nm) and the wavelength of light is λ (nm).

[0121] Re=λ / 2 …(1)

[0122] Specifically, when the retardation Re of the display panel 1 corresponding to each wavelength λ of light matches the condition (λ / 2) for achieving a black display specified by each wavelength λ of light, the brightness of the light having wavelength λ is minimized. This minimum brightness is referred to as the brightness valley of the light having wavelength λ. In other words, the condition for achieving a black display specified by each wavelength λ of light refers to the retardation value of the liquid crystal layer 10 with zero transmittance in a configuration where the liquid crystal layer 10 is sandwiched between the first polarizer 14a and the second polarizer 14b. This is determined by the relationship between the polarization state of light passing through the liquid crystal layer 10 and the second polarization axis B of the second polarizer 14b.

[0123] However, it is difficult to set the condition satisfying equation (1) for all wavelengths of light in the display panel 1. Therefore, a configuration is conceivable in which the condition is set so as to satisfy equation (1) for light of one wavelength (for example, light of the wavelength of G among R, G, and B).

[0124] Here, when the display panel 1 is set to satisfy the condition of mathematical formula (1) for light of wavelength G, the condition of mathematical formula (1) cannot be satisfied for light of wavelength R and light of wavelength B. Therefore, when a black display is performed, light of wavelengths other than G (for example, light of wavelength R and light of wavelength B) leaks from the display panel 1.

[0125] That is, when the amount of light leakage from the display panel 1 generated when black display is performed is represented by T, T has a proportional relationship represented by the following mathematical formula (2).

[0126] T∝sin 2 (2π(Re / λ)) …(2)

[0127] When equation (1) is satisfied for light of a certain wavelength, the light leakage amount T for the light of that wavelength is 0. However, when equation (1) is not satisfied for other wavelengths, the value of the light leakage amount T from the display panel 1 becomes larger.

[0128] As described above, in the display panel 1 , when the light of one wavelength is set to satisfy the mathematical formula (1), the value of the light leakage amount T in the display panel 1 becomes large, and the contrast becomes small.

[0129] Therefore, in the see-through display 100 of the first modification of the first embodiment, the color filter 12 is improved so that the light of R wavelength, the light of G wavelength, and the light of B wavelength are at the luminance valley value during black display.

[0130] Specifically, in the see-through display 100 according to the first modified example of the first embodiment, the thickness of each of the red, green, and blue transmission filters 20, 21, and 22 constituting the color filter 12 is modified to adjust the cell thickness of the liquid crystal layer 10. Furthermore, within the range of the drive voltage of the display panel 1, the R wavelength light transmitted through the red transmission filter 20, the G wavelength light transmitted through the green transmission filter 21, and the B wavelength light transmitted through the blue transmission filter 22 are configured to have a luminance valley.

[0131] First, refer to Figure 17 , the structure of a display panel 501 including a color filter 512 commonly used as a comparative example will be described. Figure 17 It is a cross-sectional view schematically showing the configuration of a liquid crystal layer 510 and a color filter 512 included in a display panel 501 according to a comparative example of the first embodiment of the present invention.

[0132] like Figure 17 As shown, in the display panel 501 of the comparative example, the color filter 512 is configured such that the red and green transmission filters 520 and 521 have equal thicknesses, while the blue transmission filter 522 has a greater thickness than the red and green transmission filters 520 and 521. In other words, in the liquid crystal layer 510, the cell thicknesses d1 and d2 of the regions corresponding to the red and green transmission filters 520 and 521, respectively, are equal. Furthermore, in the liquid crystal layer 510, the cell thickness d3 of the region corresponding to the blue transmission filter 522 is smaller than the cell thicknesses d1 and d2 of the regions corresponding to the red and green transmission filters 520 and 521, respectively.

[0133] Here, prepare Figure 17 In an experiment, a voltage between 4V and 10V was applied to the liquid crystal layer 10 of a display panel 501 having a color filter 512 as shown. The correlation between the brightness value and the voltage (voltage-brightness characteristics) was investigated for light passing through the red, green, and blue transmission filters 520, 521, and 522, respectively. Furthermore, a display panel driven in MVA mode was prepared, and the voltage-brightness characteristics were investigated for different cell thicknesses d1, d2, and d3. The results were: Figure 18 The graph shown.

[0134] Figure 18 It is shown together with the use Figure 17 The graph of the correlation between the luminance value of each of the light with a wavelength of R, the light with a wavelength of G, and the light with a wavelength of B and the voltage when the color filter 512 is applied to the liquid crystal layer 510 is shown. Figure 18 In FIG, the voltage-luminance characteristics of light of wavelength R, the voltage-luminance characteristics of light of wavelength G, and the voltage-luminance characteristics of light of wavelength B are shown in order from the bottom. Figure 18 In each of the graphs shown, the vertical axis represents the brightness value, and the horizontal axis represents the applied voltage.

[0135] In addition, Figure 18 In the curve diagram of the wavelength of light of R, the solid line represents the voltage-brightness characteristics when the unit thickness d1 is 3.0µm, the dotted line represents the voltage-brightness characteristics when the unit thickness d1 is 3.3µm, the long dotted line represents the voltage-brightness characteristics when the unit thickness d1 is 3.6µm, and the single-dot chain line represents the voltage-brightness characteristics when the unit thickness d1 is 3.9µm.

[0136] exist Figure 18 In the curve diagram of light with a wavelength of G, the solid line represents the voltage-brightness characteristics when the unit thickness d2 is 3.0μm, the dotted line represents the voltage-brightness characteristics when the unit thickness d2 is 3.3μm, the long dotted line represents the voltage-brightness characteristics when the unit thickness d2 is 3.6μm, and the single-dot chain line represents the voltage-brightness characteristics when the unit thickness d2 is 3.9μm.

[0137] exist Figure 18 In the curve diagram of light with a wavelength of B, the solid line represents the voltage-brightness characteristics when the unit thickness d3 is 2.8μm, the dotted line represents the voltage-brightness characteristics when the unit thickness d3 is 3.1μm, the long dotted line represents the voltage-brightness characteristics when the unit thickness d3 is 3.4μm, and the single-dot chain line represents the voltage-brightness characteristics when the unit thickness d3 is 3.7μm.

[0138] according to Figure 18 It can be seen that when the cell thicknesses d1, d2, and d3 are changed, the positions at which the brightness valleys of light with a wavelength of R, light with a wavelength of G, and light with a wavelength of B appear also change. In other words, it can be seen that by controlling the thicknesses of the cell thicknesses d1, d2, and d3, the conditions under which the brightness values ​​of light with a wavelength of R, light with a wavelength of G, and light with a wavelength of B reach their minimum values ​​(brightness valleys) can be controlled.

[0139] Furthermore, for each of the cell thicknesses d1, d2, and d3, the greater the thickness, the smaller the applied voltage required to reach a brightness valley for each of the luminance values ​​of light with a wavelength of R, light with a wavelength of G, and light with a wavelength of B. Furthermore, for light with a wavelength of R, no brightness valley occurs within the driving voltage range except when the cell thickness is 3.9µm.

[0140] In addition, if Figure 18 As shown, the brightness value of the point where the brightness is at a valley is not 0 for each of the light with a wavelength of R, the light with a wavelength of G, and the light with a wavelength of B. This is because even if the aforementioned correlation is examined for the light transmitted through the red transmission filter film 520, the green transmission filter film 521, and the blue transmission filter film 522, light of different wavelengths is mixed in each light.

[0141] This shows that it is preferable to construct the color filter 12 so that a luminance valley occurs within the driving voltage range and the cell thickness d1, cell thickness d2, and cell thickness d3 are each as small as possible. Based on the results of this comparative example, in the see-through display 100 of the first modified example of the first embodiment, the color filter 12 included in the display panel 1 is constructed as follows.

[0142] That is, the display panel 1 has a color filter 12, which includes: a red transmission filter film 20, which allows light corresponding to the wavelength band of the red sub-pixel to pass through; a green transmission filter film 21, which allows light corresponding to the wavelength band of the green sub-pixel to pass through; and a blue transmission filter film 22, which allows light corresponding to the wavelength band of the blue sub-pixel to pass through.

[0143] And, as Figure 19 As shown, the color filter 12 is constructed as follows: the thickness of the red transmission filter film 20 is thinner than the thickness of each of the blue transmission filter film 22 and the green transmission filter film 21, and the difference between the thickness of the green transmission filter film 21 and the thickness of the blue transmission filter film 22 is less than half of the difference between the thickness of the red transmission filter film 20 and the thickness of the blue transmission filter film 22.

[0144] Figure 19 1 is a cross-sectional view schematically showing the configuration of the liquid crystal layer 10 and the color filter 12 included in the display panel 1 according to the first modification of the first embodiment of the present invention. Figure 19 As shown, a liquid crystal layer 10 is provided between a first glass substrate 13a and a second glass substrate 13b. In addition, a color filter 12 is provided on the main surface of the second glass substrate 13b on the liquid crystal layer 10 side.

[0145] Figure 19In the example shown, the green transmission filter 21 and the blue transmission filter 22 have the same thickness, and the red transmission filter 20 is thinner than the green and blue transmission filters 21 and 22 .

[0146] In other words, in the color filter 12, the cell thickness d1 of the liquid crystal layer 10 corresponding to the red transmission filter film 20 is thicker than the cell thicknesses d2 and d3 of the liquid crystal layer 10 corresponding to the green transmission filter film 21 and the blue transmission filter film 22, respectively. Furthermore, the difference between the cell thickness d2 of the liquid crystal layer 10 corresponding to the green transmission filter film 21 and the cell thickness d3 of the liquid crystal layer 10 corresponding to the blue transmission filter film 22 is less than half the difference between the cell thickness d1 of the liquid crystal layer 10 corresponding to the red transmission filter film 20 and the cell thickness d3 of the liquid crystal layer 10 corresponding to the blue transmission filter film 22. Furthermore, in Figure 19 In the example shown, the difference between the cell thickness d1 and the cell thickness d2 is equal to the difference between the cell thickness d1 and the cell thickness d3.

[0147] Or, as Figure 20 As shown, the color filter 12 is constructed to include a red transmission filter film 20, a green transmission filter film 21, and a blue transmission filter film 22 of equal thickness, with a transparent film 23 disposed between the green transmission filter film 21 and the blue transmission filter film 22 and the second glass substrate 13b. With this configuration, the display panel 1 can also have a configuration in which the cell thicknesses d1, d2, and d3 of the liquid crystal layer 10 satisfy the aforementioned relationship. Figure 20 It is a cross-sectional view schematically showing the configuration of a liquid crystal layer 10 and a color filter 12 included in a display panel 1 according to a first modification of the first embodiment of the present invention.

[0148] Specifically, if Figure 20 As shown, a liquid crystal layer 10 is provided between a first glass substrate 13a and a second glass substrate 13b. Furthermore, a color filter 12 is disposed on the main surface of the second glass substrate 13b on the liquid crystal layer 10 side. The red, green, and blue transmission filters 20, 21, and 22 included in the color filter 12 have equal film thicknesses. However, a transparent film 23 is provided between the green and blue transmission filters 21, 22, and the second glass substrate 13b.

[0149] Thus, by providing the transparent film 23, the cell thickness d1 in the liquid crystal layer 10 is configured to be thicker than the cell thicknesses d2 and d3. Furthermore, the difference between the cell thickness d2 of the liquid crystal layer 10 and the cell thickness d3 of the liquid crystal layer 10 is configured to be less than or equal to half the difference between the cell thickness d1 of the liquid crystal layer 10 and the cell thickness d3 of the liquid crystal layer 10.

[0150] As described above, the display panel 1 constructs the color filter 12 in such a manner that the unit thicknesses d1, d2, and d3 in the liquid crystal layer 10 have the above-mentioned relationship, so that a brightness valley appears within the range of the driving voltage, and the color filter 12 is constructed in such a manner that the thicknesses of the unit thicknesses d1, d2, and d3 are as small as possible.

[0151] Furthermore, by setting the cell thicknesses d1 , d2 , and d3 as described above, the luminance of each of the light with a wavelength of R, the light with a wavelength of G, and the light with a wavelength of B can be controlled to have a luminance valley value.

[0152] However, when displaying black, even if the luminances of the light with the wavelengths R, G, and B are not at the valley value, the desired contrast can sometimes be achieved in the see-through display 100. In this case, the thicknesses of the red transmission filter 20, the green transmission filter 21, and the blue transmission filter 22 can be set so that, within the range of the drive voltage applied by the drive circuit unit 6, the luminance value is five times or less of the valley value in the voltage-luminance characteristic representing the correlation between the luminance of light transmitted through the red transmission filter 20, the green transmission filter 21, and the blue transmission filter 22 and the voltage applied to the liquid crystal layer 10.

[0153] In other words, in the voltage-brightness characteristics, the unit thicknesses d1, d2, and d3 of the liquid crystal layer 10 corresponding to the red transmittance filter film 20, the green transmittance filter film 21, and the blue transmittance filter film 22, respectively, can be set so that the brightness value within the driving voltage range is less than 5 times the brightness valley value.

[0154] Specifically, the cell thicknesses d1, d2, and d3 of the liquid crystal layer 10 are preferably set so that the luminance of all R, G, and B wavelengths falls within the brightness valley within the driving voltage range, in terms of voltage-luminance characteristics. However, it is sometimes difficult to set the cell thicknesses d1, d2, and d3 so that the luminance of all R, G, and B wavelengths falls within the brightness valley. Therefore, a range of up to five times the brightness valley is specified as the allowable luminance range for black display.

[0155] However, as described above, when black display is performed, depending solely on the setting of unit thicknesses d1, d2, and d3, the brightness of at least one of the light with a wavelength of R, the light with a wavelength of G, and the light with a wavelength of B will not be less than 5 times the brightness valley value, and sometimes the contrast becomes low.

[0156] Therefore, the display panel 1 according to the first modified example of the first embodiment may also be configured to vary the voltage applied by the drive circuit unit 6 for each sub-pixel when displaying black. By varying the voltage applied to each sub-pixel in this manner, the display panel 1 is controlled so that the luminance of each of the light with a wavelength of R, the light with a wavelength of G, and the light with a wavelength of B reaches a luminance valley value.

[0157] Specifically, if Figure 21 As shown, the cell thicknesses d1 , d2 , and d3 and the value of the applied driving voltage are appropriately set corresponding to each of the R, G, and B sub-pixels. Figure 21 This is a graph showing an example of the correlation between the luminance values ​​of light of R wavelength, light of G wavelength, and light of B wavelength and the voltage when the driving circuit unit 6 applies a voltage to the display panel 1 according to the first modification of the first embodiment of the present invention. Figure 21 In the graph shown, the vertical axis represents brightness and the horizontal axis represents voltage. In addition, the dotted line represents the voltage-brightness characteristics of light with a wavelength of B, the single-dot chain line represents the voltage-brightness characteristics of light with a wavelength of G, and the solid line represents the voltage-brightness characteristics of light with a wavelength of R. Figure 21 The correlation represented by the curve graph is obtained under the following conditions.

[0158] Specifically, the cell thickness d1 in the liquid crystal layer 10 is set to 3.9 μm, and the cell thicknesses d2 and d3 are set to 3.4 μm. Furthermore, when displaying black, the voltage applied to the liquid crystal layer 10 corresponding to the R sub-pixel is set to 7.2 V, the voltage applied to the liquid crystal layer 10 corresponding to the G sub-pixel is set to 6.3 V, and the voltage applied to the liquid crystal layer 10 corresponding to the B sub-pixel is set to 5.3 V, so that the luminance of each of the R, G, and B wavelengths reaches a luminance valley value.

[0159] In this way, when displaying black, the voltage applied to the liquid crystal layer 10 is controlled according to the cell thicknesses d1, d2, and d3 and the R, G, and B sub-pixels, so that the luminance of light with the wavelengths of R, G, and B reaches a valley value. This allows the display panel 1 to suppress light leakage during black display and improve contrast. Furthermore, the see-through display 100 according to the first variation of the first embodiment can display black accurately within the range of the drive voltage applied by the drive circuit unit 6.

[0160] [Second Modification]

[0161] Next, the configuration of the see-through display 100 according to the second modified example of the first embodiment of the present invention will be described.

[0162] In the see-through display 100, when in a transparent display state, that is, when displaying the background (transmitted image) on the back side of the display panel 1, the transmittance of light passing through the display panel 1 also becomes important. In particular, when the brightness of the light source cannot be freely set by the illumination unit 3, the transmittance of light passing through the display panel 1 becomes an important factor in evaluating the visibility of the transmitted image.

[0163] Therefore, in the see-through display 100 according to the second modified example of the first embodiment, the color filter 12 further includes a white transparent filter film 24 on the display panel 1. Figure 22 As shown, the see-through display 100 according to the second modified example of the first embodiment has a configuration in which the color filter 12 further includes a white-transmitting filter film 24 that transmits light corresponding to white sub-pixels (transparent areas) in the see-through display 100 according to the first embodiment and the first modified example of the first embodiment.

[0164] Except for this point, the see-through display 100 according to the second modification of the first embodiment has the same configuration as the see-through display 100 according to the first embodiment and the first modification of the first embodiment. Therefore, the same reference numerals are given to the same components, and their descriptions are omitted. Figure 22 It is a perspective view schematically showing the configuration of a main part of a display panel 1 according to a second modification of the first embodiment of the present invention.

[0165] That is, in the see-through display 100 according to the first embodiment and the first modified example of the first embodiment, each of the plurality of pixels constituting the image displayed on the display panel 1 includes an R sub-pixel (red sub-pixel), a G sub-pixel (green sub-pixel), and a B sub-pixel (blue sub-pixel). Figure 5 As shown, the color filter 12 includes a red transmission filter film 20, a green transmission filter film 21, and a blue transmission filter film 22, arranged in this order from the left in the horizontal direction. That is, in the display panel 1, a plurality of sub-pixels are arranged in the order of R sub-pixels, G sub-pixels, and B sub-pixels in the horizontal direction.

[0166] On the other hand, in the see-through display 100 according to the second modification of the first embodiment, as shown in FIG. Figure 23As shown, the color filter 12 has a plurality of sub-pixels arranged horizontally in the order of R sub-pixels, G sub-pixels, and B sub-pixels. Furthermore, W sub-pixels (white sub-pixels) are inserted between each of the R sub-pixels, G sub-pixels, and B sub-pixels. In other words, each pixel is composed of an R sub-pixel, a G sub-pixel, a B sub-pixel, and three W sub-pixels. Furthermore, these sub-pixels are arranged in the order of R sub-pixels, W sub-pixels, G sub-pixels, W sub-pixels, B sub-pixels, and W sub-pixels. Figure 23 This is a diagram schematically showing an example of an arrangement pattern of sub-pixels constituting each pixel of the display panel 1 according to the second modification of the first embodiment of the present invention.

[0167] Furthermore, it suffices that the proportion of W sub-pixels in each pixel satisfies at least one of the following conditions.

[0168] That is, in each pixel, the ratio of the area occupied by the W sub-pixel to the area occupied by the R sub-pixel, the G sub-pixel, and the B sub-pixel is in the range of 0.5 or more and 1.5 or less. In addition, when the areas of the R sub-pixel, the G sub-pixel, the B sub-pixel, and the W sub-pixel are equal, the number of W sub-pixels contained in each pixel is in the range of 2 / 3 or more and 3 / 3 or less of the total number of the R sub-pixels, the G sub-pixels, and the B sub-pixels. Figure 23 In the sub-pixel arrangement pattern shown, in each pixel, the ratio of the area occupied by the W sub-pixel to the area occupied by the R sub-pixel, the G sub-pixel, and the B sub-pixel is 1.0. The number of W sub-pixels is 3 / 3 of the total number of R sub-pixels, G sub-pixels, and B sub-pixels.

[0169] Therefore, in the see-through display 100 according to the second modified example of the first embodiment, the transmittance of light passing through the display panel 1 can be increased.

[0170] Therefore, the see-through display 100 can maintain good display quality.

[0171] Furthermore, the arrangement pattern of the R sub-pixels, G sub-pixels, B sub-pixels, and W sub-pixels may be the following arrangement pattern: that is, a plurality of sub-pixels are arranged in the order of R sub-pixels, B sub-pixels, and G sub-pixels. Furthermore, the arrangement pattern may be such that W sub-pixels are inserted between each of the R sub-pixels, B sub-pixels, and G sub-pixels.

[0172] Alternatively, the R sub-pixel, the G sub-pixel, the B sub-pixel, and the W sub-pixel may also be Figure 24 The arrangement pattern shown. Figure 24 This is a diagram schematically showing an example of an arrangement pattern of sub-pixels constituting each pixel of the display panel 1 according to the second modification of the first embodiment of the present invention.

[0173] like Figure 24As shown, in the horizontal direction of the display panel 1, a plurality of sub-pixels are arranged in the order of R sub-pixels, G sub-pixels, and B sub-pixels. In addition, a plurality of W sub-pixels ( Figure 24 An arrangement pattern in which 3 W sub-pixels are arranged at equal intervals in the vertical direction.

[0174] Should Figure 24 The arrangement pattern shown is also consistent with Figure 23 The arrangement pattern shown similarly satisfies the above-mentioned condition that specifies the ratio of W sub-pixels in each pixel.

[0175] However, the display panel 1 is driven by AC in order to prevent screen burn-in. Therefore, the polarity of the sub-pixel is reversed every 1 frame. Figure 23 As shown in FIG. 1 , when the sub-pixels are arranged in the order of R sub-pixel, W sub-pixel, G sub-pixel, W sub-pixel, B sub-pixel, and W sub-pixel, when the display panel 1 is driven in such a manner that the polarity is inverted in adjacent sub-pixels, the polarity of each sub-pixel is as follows: Figure 25 shown. Figure 25 This is a diagram showing an example of the correspondence between the arrangement pattern of sub-pixels and the polarity of each sub-pixel constituting each pixel of a display panel according to a comparative example of the first embodiment of the present invention.

[0176] like Figure 25 As shown in the figure, when the polarity of adjacent sub-pixels is reversed in the sub-pixel arrangement pattern, the polarity of all R sub-pixels, all G sub-pixels, and all B sub-pixels becomes the same. Therefore, when displaying a single color (for example, red) at a low frame rate of 60 Hz or less, flicker may sometimes be observed.

[0177] Therefore, in the see-through display 100 according to the second modified example of the first embodiment, when adjacent sub-pixels in the sub-pixel arrangement pattern are set as one sub-pixel pair, the driving circuit unit 6 (source driver 60 (see below)) Figure 27 )) is controlled so that voltages of different polarities are applied to each adjacent sub-pixel pair, and the polarity of each sub-pixel pair is reversed every frame.

[0178] That is, Figure 26 As shown, in the subpixel arrangement pattern, for example, the first and second subpixels are set as a first subpixel pair, the third and fourth subpixels are set as a second subpixel pair, and the fifth and sixth subpixels are set as a fourth subpixel pair. Voltage is then applied so that the polarities of the adjacent first and second subpixel pairs differ, and so that the polarities of the second and third subpixel pairs differ. Furthermore, voltage is applied from the driver circuit unit 6 so that the polarity of each subpixel pair is reversed every frame. Figure 26This is a diagram showing an example of a correspondence between an arrangement pattern of sub-pixels constituting each pixel of the display panel 1 and the polarity of each sub-pixel according to a second modification of the first embodiment of the present invention.

[0179] In addition, in order to Figure 26 With the polarity shown reversed, the see-through display 100 is constructed as follows.

[0180] That is, in Figure 25 In the relationship between the sub-pixel arrangement pattern and polarity shown, for example, for the second and third sub-pixels, the sixth and seventh sub-pixels, the tenth and eleventh sub-pixels, the fourteenth and fifteenth sub-pixels, the eighteenth and nineteenth sub-pixels, the twenty-second and twenty-third sub-pixels, the connection lines between the output terminal of the driver circuit unit 6 and the input terminal of the display panel 1 intersect. Figure 26 In FIG. 1 , a portion where the connection lines between the output terminals of the source driver 60 and the input terminals of the display panel 1 are crossed to change the polarity is shown by black filling.

[0181] However, the see-through display 100 is not limited to the aforementioned configuration of crossing connecting lines between some sub-pixels to switch polarity. For example, the design of the TFT substrate (not shown) may be modified so that the source driver 60 applies voltages of different polarities to adjacent sub-pixel pairs.

[0182] With this configuration, the see-through display 100 according to the second variation of the first embodiment can prevent all R sub-pixels, all G sub-pixels, and all B sub-pixels from having the same polarity. Therefore, flicker can be prevented even when displaying a single color (e.g., red) at a low frame rate of 60 Hz or less.

[0183] [Third Modification]

[0184] Next, the configuration of a see-through display 100 according to a third variation of the first embodiment of the present invention will be described. The see-through display 100 according to the third variation of the first embodiment further improves the color saturation of an image displayed on the display panel 1 in the configuration of the see-through display 100 according to the first embodiment, the first variation of the first embodiment, or the second variation of the first embodiment.

[0185] The see-through display 100 according to the third modified example of the first embodiment has the same configuration as the see-through display 100 according to the first embodiment, the first modified example of the first embodiment, or the second modified example of the first embodiment, except that the configuration of the display panel 1 is improved to increase the saturation of the displayed image. Therefore, identical components are denoted by identical reference numerals, and their descriptions are omitted.

[0186] As described above, the display panel 1 having normally white characteristics has a lower contrast ratio than the display panel having normally black characteristics. As a result, when the contrast ratio is reduced, the color reproduction range of primary colors decreases, and the saturation of the image displayed on the display panel 1 decreases.

[0187] Therefore, the see-through display 100 according to the third modified example of the first embodiment adopts the following configuration: a voltage is applied from the driving circuit unit 6 to each pixel of the display panel 1 within the driving voltage range so that the grayscale brightness characteristic (γ characteristic) of the display panel 1 becomes Figure 27 Grayscale brightness characteristics shown. Figure 27 This is a graph showing grayscale luminance characteristics in the display panel 1 according to the third modified example of the first embodiment of the present invention.

[0188] exist Figure 27 In the figure, the vertical axis represents brightness and the horizontal axis represents grayscale. Figure 27 The curve indicated by the dotted line represents the grayscale brightness characteristics of a standard display panel, and the curve indicated by the solid line represents the grayscale brightness characteristics of the display panel 1 .

[0189] The grayscale brightness characteristics of the display panel 1 are color rendering characteristics that can be expressed by the correlation between the grayscale input to the display panel 1 (grayscale data) and the output (brightness) of the display panel 1. The grayscale brightness characteristics of a standard display panel (grayscale brightness characteristics of a display panel serving as a reference) can be expressed by Y=L when the input grayscale data is set to L and the brightness of the display panel 1 is set to Y. γ This relationship is expressed. In this case, γ can be, for example, 2.2. However, the value of γ is not limited to 2.2. For example, depending on the manufacturer of a PC monitor or TV accessory, the value of γ may be set to a value other than 2.2.

[0190] That is, the minimum value of the grayscale data L is L_min, the maximum value is L_max, and arbitrary values ​​of the grayscale data L are L_a, L_b, and L_c. In this case, the relationship of L_min<L_a<L_b<L_c<L_max is satisfied.

[0191] In addition, the brightness Y of the display panel 1 corresponding to L_min, L_a, L_b, L_c, and L_max is respectively set to Y_min, Y_a, Y_b, Y_c, and Y_max. In addition, in the relationship between the grayscale data L and the brightness γ, when the value of the grayscale data L is L_b and the brightness Y is Y_b, the grayscale brightness characteristic (Y=L_min) of the standard display panel is obtained. γ ) is a value on the curve. In this case, the relationship of the following mathematical formula (3) holds.

[0192] (Y_b-Y_min)÷(Y_max-Y_min)=((L_b-L_min)÷(L_max-L_min)) γ …(3)

[0193] Therefore, γ can be defined as a value that satisfies the relationship of the following mathematical formula (4) based on the mathematical formula (3). γ = log ((Y_b - Y_min) ÷ (Y_max - Y_min)) ÷ log ((L_b - L_min) ÷ (L_max - L_min)) … (4)

[0194] When γ is defined as shown in equation (4), the drive circuit unit 6 is configured to apply voltages to each pixel of the display panel 1 so that Y_a and Y_c satisfy the following equations (5) and (6), respectively. Y_a<((L_a-L_min)÷(L_max-L_min)) γ …(5)

[0195] Y_c>((L_c-L_min)÷(L_max-L_min)) γ …(6)

[0196] Specifically, as mentioned above Figure 2 As shown, the see-through display 100 includes a drive circuit unit 6 that applies a voltage to each pixel of the display panel 1 to drive the pixel. The drive circuit unit 6 includes a source driver 60. When grayscale data (e.g., any grayscale value between 0 and 1024) is input from the outside, the source driver 60 supplies a voltage corresponding to the input grayscale data to the display panel 1.

[0197] The source driver 60 applies a voltage within the driving voltage range of the display panel 1 (e.g., 2.2V-7.5V) to the display panel 1 based on the input grayscale data. Thus, a voltage corresponding to the input grayscale data is applied to the display panel 1, determining the brightness of the image displayed on the display panel 1.

[0198] As described above, when γ is defined as shown in mathematical formula (4), the relationship between the grayscale data input to the source driver 60 and the voltage applied to the display panel 1 by the source driver 60 based on the grayscale data makes the brightness Y_a and Y_c satisfy the relationship of the above mathematical formulas (5) and (6).

[0199] Thus, correction can be performed so that the brightness of Y_a, which is grayscale data lower than Y_b, becomes smaller. Therefore, correction can be performed so that dark areas become darker. Conversely, correction can be performed so that the brightness of Y_c, which is grayscale data higher than Y_b, becomes larger. Therefore, correction can be performed so that bright areas become brighter. As a result, even a panel with low contrast can visually perceive an image as if it were displayed on a panel with high contrast.

[0200] Furthermore, the driving circuit unit 6 may be configured to include a memory (not shown) that stores a lookup table indicating the relationship between the grayscale data and the voltage applied to the display panel 1 for controlling the luminance corresponding to the grayscale data.

[0201] Furthermore, the source driver 60 may be configured to, upon receiving grayscale data input, refer to a lookup table and apply a voltage corresponding to the grayscale data to the display panel 1 .

[0202] Therefore, the see-through display 100 according to the third modified example of the first embodiment is configured such that, when γ is defined as shown in equation (4), the relationship between the grayscale data input to the source driver 60 and the voltage applied to the display panel 1 by the source driver 60 based on the grayscale data is such that the luminances Y_a and Y_c satisfy the relationships of equations (5) and (6). Therefore, the saturation of the image displayed on the display panel 1 can be improved.

[0203] (Second embodiment)

[0204] Next, refer to Figure 28 、 Figure 29 and Figure 30 , a liquid crystal display 200 according to a second embodiment of the present invention will be described. Figure 28 It is a perspective view showing an example of a liquid crystal display 200 according to the second embodiment of the present invention. Figure 29 Yes Figure 28 FIG. 2 is a block diagram showing an example of the configuration of the main components of the liquid crystal display 200 . Figure 30 It is schematically represented Figure 28 A perspective view showing the main structure of a display panel 201 included in a liquid crystal display 200 is shown. Figure 31 It is schematically represented Figure 30 A perspective view showing an example of a light transmission state of the display panel 201 shown.

[0205] like Figure 28 As shown in FIG. 2 , the liquid crystal display 200 of the second embodiment is a display device for displaying images such as videos. Figure 29As shown, the liquid crystal display 200 includes a display panel 201 and a drive circuit unit 6 . The back surface of the display panel 201 is covered by a back panel (not shown) that does not transmit light.

[0206] like Figure 30 As shown, the display panel 201 includes a liquid crystal layer 10, a first electrode 31 and a second electrode 32, a color filter 12, a pair of glass substrates 13, a pair of polarizing plates 14, a pair of retardation films 15, and a backlight 16. Specifically, the display panel 201 has the same configuration as the display panel 1 of the first embodiment, except for the retardation films 15 and the backlight 16. Therefore, identical components are denoted by identical reference numerals, and their descriptions may be omitted.

[0207] The backlight 16 is a light source for displaying images on the liquid crystal display 200. The backlight 16 is provided on the back side of the liquid crystal layer 10 in the display panel 201, and emits light from the back side to the front side.

[0208] The retardation film 15 is an optical film that modifies the polarization properties of light passing through the liquid crystal layer 10 or the polarizing plate 14. It includes a first retardation film 15a and a second retardation film 15b. The first retardation film 15a is positioned between the liquid crystal layer 10 and the first polarizing plate 14a, more specifically, between the first glass substrate 13a and the first polarizing plate 14a. Meanwhile, the second retardation film 15b is positioned between the liquid crystal layer 10 and the second polarizing plate 14b, more specifically, between the second glass substrate 13b and the second polarizing plate 14b.

[0209] Because the liquid crystal display 200 includes the retardation film 15, even if a situation occurs in which the retardation value of the liquid crystal layer 10 does not reach λ / 2 during black display, and a sufficient black display cannot be achieved, this situation can be improved. Specifically, even if the maximum voltage that can be applied by the drive circuit unit 6 within the drive voltage range (the voltage when the brightness reaches TB) is applied to the liquid crystal layer 10, for example, when the retardation value of the liquid crystal layer 10 only increases to 230nm when the wavelength λ of light is 550nm, by using a retardation film with a retardation value of 45nm as the first retardation film 15a, the total retardation value of the liquid crystal layer 10 and the retardation film is 275nm, which enables a sufficient black display. In addition, in order to achieve a good black display in the liquid crystal layer 10, when the retardation film 15 is used, the brightness of white is also reduced. However, if the retardation value of the retardation film 15 is 50nm or less, this disadvantage is minimal, and the effect of achieving a sufficient black display is greater.

[0210] More specifically, the axis parallel to the axis rotated 45 degrees clockwise about the first polarization axis A is designated as the a-axis, and the axis parallel to the axis rotated 45 degrees counterclockwise about the first polarization axis A is designated as the b-axis. Here, the axial direction of the slow axes of both the first retardation film 15a and the second retardation film 15b coincides with the axial direction of the a-axis or the axial direction of the b-axis. Furthermore, in the display panel 201, the phase difference of light passing through the first retardation film 15a is less than 50 nm, and the phase difference of light passing through the second retardation film 15b is also less than 50 nm.

[0211] Furthermore, when the axial direction of the slow axis of the first retardation film 15a and the second retardation film 15b coincides with the axial direction of the a-axis, the axial direction of the fast axis of the first retardation film 15a and the second retardation film 15b coincides with the axial direction of the b-axis. Conversely, when the axial direction of the slow axis of the first retardation film 15a and the second retardation film 15b coincides with the axial direction of the b-axis, the axial direction of the fast axis of the first retardation film 15a and the second retardation film 15b coincides with the axial direction of the a-axis. Therefore, the value representing the refractive index anisotropy of the retardation film 15 can be expressed by Δn=|na-nb| in the same manner as the value representing the refractive index anisotropy of the liquid crystal layer 10 defined in the first embodiment. In addition, when the film thickness of the retardation film 15 is d_ pf When the phase difference of light passing through the phase difference film 15 can be achieved through d_ pf △n is obtained.

[0212] Furthermore, the slow axis of the liquid crystal layer 10 also coincides with the a-axis or the b-axis, and when the applied voltage of the display panel 201 is below the threshold voltage, the phase difference of light passing through the liquid crystal layer 10 is also below 50 nm. Therefore, the phase difference of the liquid crystal layer 10 can be calculated using dΔn, as defined in the first embodiment.

[0213] Thus, the display panel 201 has a normally white structure, and the phase difference of light passing through the retardation film 15 is reduced to less than 50 nm. Therefore, in the display panel 201, when the liquid crystal molecules are in the initial alignment, the transmittance of light emitted from the backlight 16 through the liquid crystal layer 10 and the polarizing plate 14 can be increased.

[0214] However, in the liquid crystal display 200, the driving mode of the display panel 201 is the same as that of the display panel 1 included in the see-through display 100 of the first embodiment, the VA mode. Specifically, a first electrode 31 serving as a pixel electrode is provided on the first glass substrate 13a side, and a second electrode 32 serving as a common electrode is provided on the second glass substrate 13b side. An electric field is applied from the first electrode 31 to the second electrode 32. Furthermore, when the applied voltage is below the threshold voltage, the plurality of liquid crystal molecules 10a are uniformly aligned. A detailed description of the VA mode is omitted here, as it has already been described in the first embodiment.

[0215] In addition, the driving mode of the display panel 201 is not limited to the VA mode. For example, the driving mode of the display panel 201 can also be the IPS mode. When the driving mode is the IPS mode, the display panel 201 is provided with a first electrode 31 (pixel electrode) serving as a pixel electrode and a second electrode 32 (counter electrode) serving as a common electrode on the first glass substrate 13a, and an electric field is applied parallel to the in-plane direction of the first glass substrate 13a. In addition, when the applied voltage is below the threshold voltage, the plurality of liquid crystal molecules 10a are oriented in a manner parallel to the in-plane direction of the liquid crystal layer 10 and with the long axis approximately perpendicular to the first polarization axis A. Alternatively, when the applied voltage is below the threshold voltage, the plurality of liquid crystal molecules are oriented in a manner parallel to the in-plane direction of the liquid crystal layer 10 and with the long axis approximately parallel to the first polarization axis A. In addition, the detailed description of the IPS mode has been described in the first embodiment and is therefore omitted. Furthermore, the driving mode of the display panel 201 can also be the FFS mode. As for the case where the driving mode is set to the FFS mode, it has been described in the first embodiment and is therefore omitted.

[0216] Thus, when the voltage applied to the display panel 201 is below the threshold voltage, the electric field has no effect on each of the liquid crystal molecules 10a. Therefore, the liquid crystal molecules maintain their initial alignment and are uniformly aligned. Consequently, the refractive index of the liquid crystal layer 10a becomes uniform.

[0217] Furthermore, the display panel 201 according to the second embodiment may have a configuration capable of improving contrast in an image display state, similar to the display panel 1 according to the first modification of the first embodiment.

[0218] Specifically, the display panel 201 includes a color filter 12 comprising a red transmission filter 20 that transmits light corresponding to the wavelength band of a red sub-pixel, a green transmission filter 21 that transmits light corresponding to the wavelength band of a green sub-pixel, and a blue transmission filter 22 that transmits light corresponding to the wavelength band of a blue sub-pixel. Furthermore, by adjusting the thickness of each of the red transmission filter 20, green transmission filter 21, and blue transmission filter 22 included in the color filter 12, the cell thickness of the liquid crystal layer 10 corresponding to each of the red transmission filter 20, green transmission filter 21, and blue transmission filter 22 is adjusted.

[0219] Furthermore, within the range of the driving voltage of the display panel 201, the R wavelength light passing through the red transmission filter 20, the G wavelength light passing through the green transmission filter 21, and the B wavelength light passing through the blue transmission filter 22 are configured to have brightness valleys.

[0220] That is, in the color filter 12, the thickness of the red transmission filter film 20 is thinner than the thicknesses of the blue transmission filter film 22 and the green transmission filter film 21, and the difference between the thicknesses of the red transmission filter film 20 and the green transmission filter film 21 is less than half the difference between the thicknesses of the red transmission filter film 20 and the blue transmission filter film 22.

[0221] In other words, in the color filter 12, the cell thickness of the liquid crystal layer 10 corresponding to the red transmission filter film 20 is thicker than the cell thickness of the liquid crystal layer 10 corresponding to the green transmission filter film 21 and the cell thickness of the liquid crystal layer 10 corresponding to the blue transmission filter film 22. Furthermore, the difference between the cell thickness of the liquid crystal layer 10 corresponding to the red transmission filter film 20 and the cell thickness of the liquid crystal layer 10 corresponding to the green transmission filter film 21 is less than half the difference between the cell thickness of the liquid crystal layer 10 corresponding to the red transmission filter film 20 and the cell thickness of the liquid crystal layer 10 corresponding to the blue transmission filter film 22.

[0222] Alternatively, the color filter 12 is configured to include a red transmission filter film 20, a green transmission filter film 21, and a blue transmission filter film 22 having the same film thickness, and a transparent film 23 is provided between the green transmission filter film 21 and the blue transmission filter film 22 and the second glass substrate 13b. With this configuration, the cell thickness in the liquid crystal layer 10 can be configured to satisfy the above relationship.

[0223] As described above, the display panel 201 included in the liquid crystal display 200 of the second embodiment can include the color filter 12 having a cell thickness in the liquid crystal layer 10 that satisfies the above relationship, similarly to the display panel 1 included in the see-through display 100 of the first embodiment.

[0224] Therefore, the display panel 201 can be controlled so that the luminance of each of the light with a wavelength of R, the light with a wavelength of G, and the light with a wavelength of B reaches a luminance valley value.

[0225] However, when displaying black, the desired contrast can sometimes be achieved in the liquid crystal display 200 even if the luminances of the R, G, and B wavelengths are not at the valley value. In this case, the thicknesses of the red, green, and blue transmission filters 20, 21, and 22 can be set so that the luminance values ​​of the light transmitted through the red, green, and blue transmission filters 20, 21, and 22, respectively, and the voltage applied to the liquid crystal layer 10 are five times or less of the valley value within the driving voltage range. Alternatively, the cell thicknesses of the liquid crystal layer 10 corresponding to the red, green, and blue transmission filters 20, 21, and 22 can be set so that the luminance values ​​of the light transmitted through the red, green, and blue transmission filters 21, 22, respectively, are five times or less of the valley value within the driving voltage range.

[0226] Furthermore, the display panel 201 according to the second embodiment, similar to the display panel 1 according to the first embodiment, can also be configured to vary the voltage applied by the driver circuit unit 6 for each sub-pixel when displaying black. By varying the applied voltage for each sub-pixel in this manner, the display panel 201 is controlled so that the luminance of each of the R wavelength, the G wavelength, and the B wavelength reaches a luminance valley value.

[0227] Furthermore, similar to the display panel 1 of the second variation of the first embodiment, the display panel 201 of the second embodiment may also be configured to increase the transmittance of light passing through the liquid crystal layer 10 and polarizer 14 of the display panel 201. Specifically, each of the multiple pixels constituting the image displayed by the display panel 201 includes a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a white sub-pixel. Furthermore, the color filter 12 includes, in addition to the red, green, and blue transmissive filter films 20, 21, and 22, a white transmissive filter film 24 that transmits light corresponding to the white sub-pixel. Furthermore, the color filter 12 may be configured such that, in each pixel, the ratio of the area occupied by the white sub-pixel to the area occupied by the red, green, and blue sub-pixels is within a range of 0.5 to 1.5.

[0228] Alternatively, in each pixel, the color filter 12 can also be constructed as follows: when the areas of the red sub-pixels, green sub-pixels, blue sub-pixels and white sub-pixels are equal, the ratio of the number of white sub-pixels to the total number of red sub-pixels, green sub-pixels and blue sub-pixels can be in a range of greater than 2 / 3 and less than 3 / 3.

[0229] In addition, if Figure 23 or Figure 25 As shown, the sub-pixel arrangement pattern may also be a pattern in which red sub-pixels, green sub-pixels, and blue sub-pixels are arranged in the order of red sub-pixels, green sub-pixels, and blue sub-pixels in the horizontal direction of the display panel 201, with white sub-pixels inserted between each of the red sub-pixels, green sub-pixels, and blue sub-pixels. Alternatively, the sub-pixel arrangement pattern may also be a pattern in which red sub-pixels, blue sub-pixels, and green sub-pixels are arranged in the order of red sub-pixels, blue sub-pixels, and green sub-pixels in the horizontal direction of the display panel 201, with white sub-pixels inserted between each of the red sub-pixels, blue sub-pixels, and green sub-pixels.

[0230] In the liquid crystal display 200 of the second embodiment, when the sub-pixel arrangement pattern is the above-described pattern, the drive circuit unit 6 applies voltage to the display panel 201 as follows, similarly to the see-through display 100 of the second modification of the first embodiment.

[0231] That is, the driving circuit unit 6 defines a group of adjacent sub-pixels as a sub-pixel pair, and applies voltages of different polarities to the display panel 201 for each adjacent sub-pixel pair.

[0232] With this configuration, the liquid crystal display 200 according to the second embodiment can prevent the occurrence of flicker even at a low frame rate of, for example, 60 Hz or less.

[0233] Furthermore, the liquid crystal display 200 of the second embodiment may have a configuration capable of improving the saturation of a displayed image, similar to the see-through display 100 of the third modified example of the first embodiment.

[0234] Specifically, in the liquid crystal display 200 of the second embodiment, the driving circuit unit 6 includes a source driver 60 and a TCON substrate 61. When grayscale data (e.g., any grayscale value between 0 and 1024) is input from the outside, a voltage corresponding to the input grayscale data is supplied to the display panel 201. Specifically, the grayscale data is input to the source driver 60 via the TCON substrate 61. The source driver 60 is configured to apply a voltage within a range of driving voltages for the display panel 201 to each pixel of the display panel 201 based on the input grayscale data.

[0235] Here, in the liquid crystal display 200 of the second embodiment, similarly to the see-through display 100 of the third modified example of the first embodiment, when the minimum value of grayscale data input from the outside is set to L_min, the maximum value is set to L_max, and arbitrary values ​​of the grayscale data are set to L_a, L_b, and L_c, and the relationship L_min<L_a<L_b<<L_c<L_max is satisfied, the brightness of the display panel 201 corresponding to L_min, L_a, L_b, L_c, and L_max is set to Y_min, Y_a, Y_b, Y_c, and Y_max, respectively. Wherein L_b and Y_b satisfy Y=L, which represents the grayscale brightness characteristic of the standard display panel 201 (the grayscale brightness characteristic of the display panel 201 serving as a reference). γ relationship. At this time, γ is γ=log((Y_b-Y_min)÷(Y_max-Y_min))÷log((L_b-L_min)÷(L_max-L_min)).

[0236] When γ is defined in this way, the source driver 60 included in the driving circuit unit 6 is driven so that the luminances Y_a and Y_c satisfy Y_a<((L_a-L_min)÷(L_max-L_min)) γ , Y_c>((L_c-L_min)÷(L_max-L_min)) γ The voltage is applied to the display panel 201 in a manner related to the relationship between the display panel and the display panel.

[0237] Therefore, the liquid crystal display 200 of the second embodiment can improve the chromaticity of the image displayed by the display panel 201. Furthermore, the polarizing plate can be said to have the function of emitting incident natural light as linearly polarized light. Therefore, the polarizing plate includes not only the aforementioned polarizing plate 14 but also a retardation film 15 that has the function of rotating the polarization axis. Furthermore, the polarization axis is the polarization axis of the emitted linearly polarized light. Therefore, in the liquid crystal display 200 of the second embodiment, the polarizing plate 14 and the retardation film 15 can be considered together as a polarizing plate.

[0238] (Variation)

[0239] Next, refer to Figure 31 The configuration of a liquid crystal display 200 according to a modification of the second embodiment will be described. Figure 31 This is a perspective view schematically showing an example of a light transmission state of a display panel 201 included in a liquid crystal display 200 according to a modification of the second embodiment of the present invention.

[0240] In the liquid crystal display 200 of the second embodiment, the first polarizing plate 14a and the second polarizing plate 14b are arranged in parallel Nicols. Figure 31As shown, in the liquid crystal display 200 according to the modification of the second embodiment, the first polarizing plate 14a and the second polarizing plate 14b are arranged in a crossed Nicols configuration, and a first retardation film 15a is provided between the liquid crystal layer 10 and the first polarizing plate 14a.

[0241] In the liquid crystal display 200 according to the modified example of the second embodiment, as shown in FIG. Figure 31 As shown, the first polarization axis A is oriented vertically along the principal surface of the vertically disposed first polarizer 14a, while the second polarization axis B is oriented horizontally along the principal surface of the vertically disposed second polarizer 14b. The slow axis of the first retardation film 15a, when viewed along the propagation direction of incident light, extends in a direction that is 45 degrees counterclockwise of the first polarization axis A. Furthermore, the polarization axis of the linearly polarized light emitted through the first polarizer 14a and the first retardation film 15a is parallel to the polarization axis of the linearly polarized light emitted from the second polarizer 14b.

[0242] In other words, when viewed along the propagation direction of incident light, the slow axis of the first retardation film 15 a is parallel to a line segment that bisects the angle formed by the first polarization axis A and the second polarization axis B. Furthermore, the retardation of the first retardation film 15 a is 1 / 2 of the wavelength transmitted through the first retardation film 15 a.

[0243] And, in Figure 31 In the illustrated configuration, the first retardation film 15a is provided between the first polarizer 14a and the first electrode 31. However, a second retardation film 15b may also be provided between the second polarizer 14b and the second electrode 32. In this configuration, the sum of the retardation of the first retardation film 15a and the retardation of the second retardation film 15b is 1 / 2 the wavelength of light. In other words, the first retardation film 15a and the second retardation film 15b each have a λ / 4 retardation.

[0244] Furthermore, the display panel 201 included in the liquid crystal display 200 according to the second embodiment and the modified example of the second embodiment can be applied as a display panel constituting a see-through display.

Claims

1. A perspective display, characterized in that: have: a display panel having a plurality of pixels; and a driving circuit for applying a voltage corresponding to input grayscale data to the plurality of pixels; The display panel has: A first substrate having pixel electrodes; a second substrate; a liquid crystal layer, sandwiched between the first substrate and the second substrate; A first polarizing plate, disposed on the first substrate, having a first polarization axis; as well as A second polarizing plate is provided on the second substrate and has a second polarization axis. When the transmittance of the pixel when the minimum voltage is applied from the driving circuit to the pixel is set to TW, and the transmittance of the pixel when the maximum voltage is applied from the driving circuit to the pixel is set to TB, a normally white characteristic satisfies the relationship TW>TB. The normally white characteristic of the display panel has the following structure: When the axis parallel to the axis rotating the first polarization axis by 45 degrees in the clockwise direction is defined as the a-axis, the axis parallel to the axis rotating the first polarization axis by 45 degrees in the counterclockwise direction is defined as the b-axis, the a-axis component of the refractive index of the liquid crystal layer is defined as na, the b-axis component is defined as nb, and the value representing the refractive index anisotropy of the liquid crystal layer, which is the difference between the refractive index of the a-axis component and the refractive index of the b-axis component, is defined as Δn=|na-nb|, The value of △n when the voltage applied to the multiple pixels by the driving circuit is below the threshold voltage is smaller than △n when the voltage applied by the driving circuit is greater than the threshold voltage, and the threshold voltage indicates the boundary of whether the orientation of the liquid crystal molecules in the liquid crystal layer is changed.

2. The see-through display according to claim 1, wherein: The second polarization axis is parallel to the first polarization axis.

3. The see-through display according to claim 1, wherein: The liquid crystal layer contains liquid crystal molecules with negative dielectric anisotropy. When the voltage applied to the plurality of pixels by the driving circuit is equal to or lower than the threshold voltage, the liquid crystal molecules are aligned in a direction in which the long axes of the liquid crystal molecules are perpendicular to the in-plane direction of the liquid crystal layer.

4. The see-through display according to claim 1, wherein: The liquid crystal layer comprises liquid crystal molecules, When the voltage applied to the plurality of pixels by the driving circuit is below the threshold voltage, the liquid crystal molecules are aligned in a direction where their long axes are parallel to the in-plane direction of the liquid crystal layer and parallel to or perpendicular to the first polarization axis.

5. The see-through display according to any one of claims 1 to 4, wherein: Each pixel in the plurality of pixels includes a red sub-pixel, a green sub-pixel, and a blue sub-pixel, The display panel includes a color filter, and the color filter includes: a red transmission filter film that transmits light corresponding to the wavelength band of the red sub-pixel; a green transmittance filter film that transmits light corresponding to a wavelength band of the green sub-pixel; and A blue transmission filter film transmits light corresponding to the wavelength band of the blue sub-pixel. In the voltage-luminance characteristics indicating the correlation between the luminance of light transmitted through the red transmission filter, the green transmission filter, and the blue transmission filter and the voltage applied to the plurality of pixels, The cell thicknesses of the liquid crystal layers corresponding to the red transmission filter film, the green transmission filter film, and the blue transmission filter film are set so that the minimum brightness value within the range of voltages applied to the multiple pixels by the driving circuit is less than or equal to 5 times the minimum brightness value in the voltage-brightness characteristics.

6. The see-through display according to any one of claims 1 to 4, characterized in that Each pixel in the plurality of pixels includes a red sub-pixel, a green sub-pixel, and a blue sub-pixel, The display panel includes a color filter, and the color filter includes: a red transmission filter film that transmits light corresponding to the wavelength band of the red sub-pixel; a green transmittance filter film that transmits light corresponding to a wavelength band of the green sub-pixel; and A blue transmission filter film transmits light corresponding to the wavelength band of the blue sub-pixel. The thickness of the red transmittance filter film is thinner than the thickness of each of the blue transmittance filter film and the green transmittance filter film, and the difference between the thickness of the green transmittance filter film and the thickness of the blue transmittance filter film is less than half of the difference between the thickness of the red transmittance filter film and the thickness of the blue transmittance filter film.

7. The see-through display according to any one of claims 1 to 4, characterized in that Each pixel in the plurality of pixels includes a red sub-pixel, a green sub-pixel, and a blue sub-pixel, The display panel includes a color filter, and the color filter includes: a red transmission filter film that transmits light corresponding to the wavelength band of the red sub-pixel; a green transmittance filter film that transmits light corresponding to a wavelength band of the green sub-pixel; and A blue transmission filter film transmits light corresponding to the wavelength band of the blue sub-pixel. The cell thickness of the liquid crystal layer corresponding to the red transmission filter is thicker than the cell thickness of the liquid crystal layer corresponding to the blue transmission filter and the green transmission filter, respectively, and the difference between the cell thickness of the liquid crystal layer corresponding to the green transmission filter and the cell thickness of the liquid crystal layer corresponding to the blue transmission filter is less than half of the difference between the cell thickness of the liquid crystal layer corresponding to the red transmission filter and the cell thickness of the liquid crystal layer corresponding to the blue transmission filter.

8. The see-through display according to any one of claims 1 to 4, wherein: Each pixel in the plurality of pixels includes a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a white sub-pixel. The display panel includes a color filter, and the color filter includes: a red transmission filter film that transmits light corresponding to the wavelength band of the red sub-pixel; A green transmission filter film that transmits light corresponding to the wavelength band of the green sub-pixel; a blue-transmitting filter film that transmits light corresponding to a wavelength band of the blue sub-pixel; and a white transmission filter film that transmits light corresponding to the white sub-pixel; In each of the pixels, a ratio of an area occupied by the white sub-pixel to an area occupied by the red sub-pixel, the green sub-pixel, and the blue sub-pixel is in a range of 0.5 to 1.

5.

9. The see-through display according to claim 8, wherein: In each of the pixels, when the areas of the red sub-pixel, the green sub-pixel, the blue sub-pixel, and the white sub-pixel are equal, the ratio of the number of white sub-pixels to the total number of the red sub-pixels, the green sub-pixels, and the blue sub-pixels is in the range of greater than 2 / 3 and less than 3 / 3.

10. The see-through display according to claim 8, wherein: In each of the pixels, the red sub-pixel, the green sub-pixel, and the blue sub-pixel are arranged in this order, or the red sub-pixel, the blue sub-pixel, and the green sub-pixel are arranged in this order. The white sub-pixel is inserted between each of the red sub-pixel, the green sub-pixel, and the blue sub-pixel, or between each of the red sub-pixel, the blue sub-pixel, and the green sub-pixel.

11. The see-through display according to claim 10, wherein: In each of the pixels, when a group of adjacent sub-pixels is defined as a sub-pixel pair, The driving circuit applies voltages of different polarities to adjacent pairs of sub-pixels, and applies a voltage that inverts the polarity of each sub-pixel pair every frame.

12. The see-through display according to any one of claims 1 to 4, wherein: When the minimum value of the grayscale data is set to L_min, the maximum value is set to L_max, and any value of the grayscale data is set to L_a, L_b, and L_c, and the relationship L_min<L_a<L_b<L_c<L_max is satisfied, The brightness of the display panel corresponding to L_min, L_a, L_b, L_c, and L_max is respectively set to Y_min, Y_a, Y_b, Y_c, and Y_max, and L_b and Y_b satisfy Y=L representing the grayscale brightness characteristic of the display panel as a reference. γ The relationship of γ satisfies γ=log((Y_b-Y_min)÷(Y_max-Y_min))÷log((L_b-L_min)÷(L_max-L_min)), The driving circuit applies the voltage to the display panel so that Y_a<((L_a-L_min)÷(L_max-L_min)) γ , Y_c>((L_c-L_min)÷(L_max-L_min)) γ relationship.

13. A perspective display, characterized in that: have: a display panel having a plurality of pixels; and a driving circuit for applying a voltage corresponding to input grayscale data to the plurality of pixels; The display panel has: A first substrate having pixel electrodes; a second substrate; a liquid crystal layer, sandwiched between the first substrate and the second substrate; A first polarizing plate, disposed on the first substrate, having a first polarization axis; as well as A second polarizing plate is provided on the second substrate and has a second polarization axis. When the transmittance of the pixel when the minimum voltage is applied from the driving circuit to the pixel is set to TW, and the transmittance of the pixel when the maximum voltage is applied from the driving circuit to the pixel is set to TB, a normally white characteristic satisfies the relationship TW>TB. The normally white characteristic of the display panel has the following structure: In the case where the axis parallel to the axis rotating the first polarization axis by 45 degrees in the clockwise direction is defined as the a-axis, the axis parallel to the axis rotating the first polarization axis by 45 degrees in the counterclockwise direction is defined as the b-axis, the a-axis component of the refractive index of the liquid crystal layer is defined as na, the b-axis component is defined as nb, the value representing the refractive index anisotropy of the liquid crystal layer, which is the difference between the refractive index of the a-axis component and the refractive index of the b-axis component, is defined as Δn=|na-nb|, the thickness of the liquid crystal layer is defined as d, and the phase difference of the liquid crystal layer is defined as dΔn, The value of dΔn when the voltage applied to the plurality of pixels by the driving circuit is equal to or less than a threshold voltage indicating a boundary for changing the alignment of liquid crystal molecules in the liquid crystal layer is 50 nm or less.

14. The see-through display according to claim 13, wherein: The second polarization axis is parallel to the first polarization axis.

15. The see-through display according to claim 13, wherein: The liquid crystal layer contains liquid crystal molecules with negative dielectric anisotropy. When the voltage applied to the plurality of pixels by the driving circuit is equal to or lower than the threshold voltage, the liquid crystal molecules are aligned in a direction in which the long axes of the liquid crystal molecules are perpendicular to the in-plane direction of the liquid crystal layer.

16. The see-through display according to claim 13, wherein: The liquid crystal layer comprises liquid crystal molecules, When the voltage applied to the plurality of pixels by the driving circuit is below the threshold voltage, the liquid crystal molecules are aligned in a direction where their long axes are parallel to the in-plane direction of the liquid crystal layer and parallel to or perpendicular to the first polarization axis.

17. The see-through display according to any one of claims 13 to 16, wherein: Each pixel in the plurality of pixels includes a red sub-pixel, a green sub-pixel, and a blue sub-pixel, The display panel includes a color filter, and the color filter includes: a red transmission filter film that transmits light corresponding to the wavelength band of the red sub-pixel; a green transmittance filter film that transmits light corresponding to a wavelength band of the green sub-pixel; and A blue transmission filter film transmits light corresponding to the wavelength band of the blue sub-pixel. In the voltage-luminance characteristics indicating the correlation between the luminance of light transmitted through the red transmission filter, the green transmission filter, and the blue transmission filter and the voltage applied to the plurality of pixels, The cell thicknesses of the liquid crystal layers corresponding to the red transmission filter film, the green transmission filter film, and the blue transmission filter film are set so that the minimum brightness value within the range of voltages applied to the multiple pixels by the driving circuit is less than or equal to 5 times the minimum brightness value in the voltage-brightness characteristics.

18. The see-through display according to any one of claims 13 to 16, wherein: Each pixel in the plurality of pixels includes a red sub-pixel, a green sub-pixel, and a blue sub-pixel, The display panel includes a color filter, and the color filter includes: a red transmission filter film that transmits light corresponding to the wavelength band of the red sub-pixel; a green transmittance filter film that transmits light corresponding to a wavelength band of the green sub-pixel; and A blue transmission filter film transmits light corresponding to the wavelength band of the blue sub-pixel. The thickness of the red transmittance filter film is thinner than the thickness of each of the blue transmittance filter film and the green transmittance filter film, and the difference between the thickness of the green transmittance filter film and the thickness of the blue transmittance filter film is less than half of the difference between the thickness of the red transmittance filter film and the thickness of the blue transmittance filter film.

19. The see-through display according to any one of claims 13 to 16, wherein: Each pixel in the plurality of pixels includes a red sub-pixel, a green sub-pixel, and a blue sub-pixel, The display panel includes a color filter, and the color filter includes: a red transmission filter film that transmits light corresponding to the wavelength band of the red sub-pixel; a green transmittance filter film that transmits light corresponding to a wavelength band of the green sub-pixel; and A blue transmission filter film transmits light corresponding to the wavelength band of the blue sub-pixel. The cell thickness of the liquid crystal layer corresponding to the red transmission filter is thicker than the cell thickness of the liquid crystal layer corresponding to the blue transmission filter and the green transmission filter, respectively, and the difference between the cell thickness of the liquid crystal layer corresponding to the green transmission filter and the cell thickness of the liquid crystal layer corresponding to the blue transmission filter is less than half of the difference between the cell thickness of the liquid crystal layer corresponding to the red transmission filter and the cell thickness of the liquid crystal layer corresponding to the blue transmission filter.

20. The see-through display according to any one of claims 13 to 16, wherein: Each pixel in the plurality of pixels includes a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a white sub-pixel. The display panel includes a color filter, and the color filter includes: a red transmission filter film that transmits light corresponding to the wavelength band of the red sub-pixel; A green transmission filter film that transmits light corresponding to the wavelength band of the green sub-pixel; a blue-transmitting filter film that transmits light corresponding to a wavelength band of the blue sub-pixel; and a white transmission filter film that transmits light corresponding to the white sub-pixel; In each of the pixels, a ratio of an area occupied by the white sub-pixel to an area occupied by the red sub-pixel, the green sub-pixel, and the blue sub-pixel is in a range of 0.5 to 1.

5.

21. The see-through display according to claim 20, wherein: In each of the pixels, when the areas of the red sub-pixel, the green sub-pixel, the blue sub-pixel, and the white sub-pixel are equal, the ratio of the number of white sub-pixels to the total number of the red sub-pixels, the green sub-pixels, and the blue sub-pixels is in the range of greater than 2 / 3 and less than 3 / 3.

22. The see-through display according to claim 20, wherein: In each of the pixels, the red sub-pixel, the green sub-pixel, and the blue sub-pixel are arranged in this order, or the red sub-pixel, the blue sub-pixel, and the green sub-pixel are arranged in this order. The white sub-pixel is inserted between each of the red sub-pixel, the green sub-pixel, and the blue sub-pixel, or between each of the red sub-pixel, the blue sub-pixel, and the green sub-pixel.

23. The see-through display according to claim 22, wherein: In each of the pixels, when a group of adjacent sub-pixels is defined as a sub-pixel pair, The driving circuit applies voltages of different polarities to adjacent pairs of sub-pixels, and applies a voltage that inverts the polarity of each sub-pixel pair every frame.

24. The see-through display according to any one of claims 13 to 16, wherein: When the minimum value of the grayscale data is set to L_min, the maximum value is set to L_max, and any value of the grayscale data is set to L_a, L_b, and L_c, and the relationship L_min<L_a<L_b<L_c<L_max is satisfied, The brightness of the display panel corresponding to L_min, L_a, L_b, L_c, and L_max is respectively set to Y_min, Y_a, Y_b, Y_c, and Y_max, and L_b and Y_b satisfy Y=L representing the grayscale brightness characteristic of the display panel as a reference. γ The relationship of γ satisfies γ=log((Y_b-Y_min)÷(Y_max-Y_min))÷log((L_b-L_min)÷(L_max-L_min)), The driving circuit applies the voltage to the display panel so that Y_a<((L_a-L_min)÷(L_max-L_min)) γ , Y_c>((L_c-L_min)÷(L_max-L_min)) γ relationship.

Images