JP2015158523A - display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device capable of suppressing decrease in display qualities due to light transmitted through a phosphor layer.SOLUTION: A display device 200 includes a backlight 20, an optical shutter 150, a phosphor layer 3, and a filter 30. The backlight 20 emits blue light. The optical shutter 150 selectively allows light entering from the backlight 20 to exit. The phosphor layer 3 is disposed to allow the light from the optical shutter 150 to enter the phosphor layer, and contains a phosphor that absorbs light entering from the optical shutter 150 and emits green fluorescent light. The filter 30 is disposed between the backlight 20 and the phosphor layer 3, and transmits light at a wavelength where an emission intensity of the blue light is the maximum and suppresses transmission of light at a wavelength where an emission intensity of the green light is the maximum.

Description

  The present invention relates to a display device.

  An example of a liquid crystal display element used as a light source that emits blue light is described in JP-A-11-52371 (Patent Document 1).

  The liquid crystal display element includes a back light source, a first polarizing layer disposed on the back light source, a first transparent substrate formed on the first polarizing layer, and a first transparent substrate formed on the first transparent substrate. 1 transparent electrode, the liquid crystal arrange | positioned on a 1st transparent substrate, the 2nd transparent electrode arrange | positioned on a liquid crystal, and the 2nd transparent substrate arrange | positioned on a 2nd transparent electrode. Furthermore, the liquid crystal display element includes a second polarizing layer disposed on the second transparent substrate, a phosphor layer formed on the second polarizing layer, and a third transparent substrate formed on the phosphor layer. Including.

  The back light source emits light in the blue region. The phosphor layer includes a red light emitting phosphor that emits red light by light from the back light source, a green phosphor that emits green light by the light from the back light source, and a transparent film for allowing light from the back light source to pass through as it is. Including.

  According to such a liquid crystal display element, it is possible to significantly reduce the light absorption loss in the color filter, and therefore, it is promising as a liquid crystal display device with high light utilization efficiency.

Japanese Patent Laid-Open No. 11-52371

  In recent years, fluorescent excitation displays have attracted attention in the display field. A fluorescent excitation display is a device that displays blue or near-ultraviolet light, performs gradation adjustment by a shutter layer, and performs color conversion by a phosphor to perform color image display. Fluorescent excitation displays retain the advantages of ideally low power consumption and wide viewing angle compared to the current mainstream liquid crystal displays.

  As one of fluorescence excitation display systems, a structure has been proposed in the past in which a blue backlight is used, color conversion is performed by phosphors in red and green pixels, and diffusion is performed by scattering materials in blue pixels.

  However, in this method, the emission wavelength range of the green phosphor and the wavelength range of the emitted light from the blue backlight are close, and part of the blue light from the blue backlight may pass through the green phosphor. As a result, there are cases where good outgoing light cannot be obtained.

  The present invention has been made in view of the above-described problems, and a main object thereof is to provide a display device capable of suppressing deterioration in display quality due to light transmitted through a phosphor layer.

  The display device according to the present invention includes a light source unit, an optical shutter, a phosphor layer, and a filter. The light source unit emits first light. The optical shutter selectively emits light incident from the light source unit. The phosphor layer is arranged so that light from the optical shutter is incident, and includes a phosphor that absorbs light incident from the optical shutter and fluoresces the second light. The filter is disposed between the light source unit and the phosphor layer, and transmits light having a wavelength that maximizes the emission intensity of the first light, and suppresses transmission of light having a wavelength that maximizes the emission intensity of the second light. To do.

In the display device, preferably, the polar angle θ, the luminous intensity spectrum P _θ of the second light emitted from the phosphor layer at the polar angle θ, the luminous intensity spectrum i _θ of the first light at the polar angle _θ , and the transmittance spectrum T of the filter. _{When F} is the transmittance spectrum T _ph of the phosphor layer, the luminous intensity l _θ of the emitted light from the phosphor layer at the polar angle _θ is l _θ = ∫ {P _θ + (i _θ · T _F · T _ph ) } In the range of −85 ° ≦ θ ≦ 85 °, the polar angle _θ and the luminous intensity l _θ of the emitted light from the phosphor layer at the polar angle θ 0.90 · A · cos θ ≦ l _θ ≦ 1.10 · A · cos θ is satisfied for an arbitrary real number A in the range of 0.91 times to 1.11 times the luminous intensity of the emitted light.

Preferably, in the display device, the phosphor layer at a polar angle of 0 ° in a range where the polar angle _θ and the luminous intensity l _θ of light emitted from the phosphor layer at the polar angle θ are in the range of −85 ° ≦ θ ≦ 85 °. 0.93 · B · cos θ ≦ l _θ ≦ 1.07 · B · cos θ is satisfied for an arbitrary real number B in the range of 0.93 to 1.076 times the luminous intensity of the light emitted from.

  Preferably, in the display device, the first light is blue light, the phosphor layer includes a green phosphor that emits green light, and the filter is disposed between the light source unit and the green phosphor.

  Preferably, the display device includes a color filter that is disposed on the opposite side of the light source unit with respect to the phosphor layer and selectively transmits light emitted from the phosphor layer.

In the display device, preferably, the polar angle θ, the luminous intensity spectrum P _θ of the second light emitted from the phosphor layer at the polar angle θ, the luminous intensity spectrum i _θ of the first light at the polar angle _θ , and the transmittance spectrum T of the filter. _{When F} is the transmittance spectrum T _ph of the phosphor layer and the transmittance spectrum T _CF of the color filter, the light intensity L _{θ of} the light transmitted through the color filter at the polar angle _θ is L _θ = ∫ {P _θ · T _CF + (I _θ · T _F · T _ph · T _CF )} dλ, and the polar angle θ and the luminous intensity L _{θ of} the light transmitted through the color filter at the polar angle θ are −85 ° ≦ θ ≦ 85 °. , 0.90 · C · cos θ ≦ L _θ for an arbitrary real number C in the range of 0.91 to 1.11 times the luminous intensity of the light emitted from the phosphor layer at a polar angle of 0 °. ≦ 1.10 · C · cos θ is satisfied.

Preferably, in the display device, the polar angle θ and the luminous intensity L _{θ of} the light transmitted through the color filter at the polar angle θ are transmitted through the color filter at the polar angle of 0 ° in the range of −85 ° ≦ θ ≦ 85 °. 0.93 · B · cos θ ≦ L _θ ≦ 1.07 · B · cos θ is satisfied for an arbitrary real number B in the range of 0.93 to 1.076 times the luminous intensity of the light.

  According to the display device of the present invention, it is possible to suppress deterioration in display quality due to light transmitted through the phosphor layer, and to improve display quality.

1 is a cross-sectional view illustrating a display device according to a first embodiment. It is sectional drawing which shows the outline | summary of the emitted light from a fluorescent substance layer. It is a schematic diagram which shows the outline of a polar angle and an azimuth. It is a figure which shows the relationship between a polar angle and a luminous intensity in case brightness | luminance is uniform irrespective of the observation angle of a display apparatus. It is a graph which shows the luminous intensity polar angle distribution of the emitted light from a fluorescent substance layer. In a display device composed of RGB pixels, when the output light from the B pixel has an error of 0% from the conditional expression, the white display chromaticity changes by ± 0.02 or more when the RG deviates from the conditional expression. It is a graph which shows. It is a graph which shows the luminous intensity polar angle distribution of the emitted light from R fluorescent substance. It is a graph which shows the luminous intensity polar angle distribution of the emitted light from G fluorescent substance. It is a graph which shows luminous intensity polar angle distribution of the emitted light from the scattering material in B pixel. 7 is a cross-sectional view illustrating a display device according to Embodiment 3. FIG. FIG. 6 is a cross-sectional view illustrating a display device according to a fourth embodiment. FIG. 10 is a cross-sectional view illustrating a display device according to a fifth embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

(Embodiment 1)
FIG. 1 is a cross-sectional view showing a display device 200 according to the first embodiment. The display device 200 shown in FIG. 1 includes a backlight 20 as a light source unit, an optical shutter 150, and a color conversion board 100. The backlight 20 includes a blue LED as a light source and a light guide plate, and emits substantially parallel blue light toward the optical shutter 150. The backlight 20 is a highly directional light source that emits light having a blue wavelength. The backlight 20 may include a plurality of blue light sources arranged in a plane without including a light guide plate. The backlight 20 may be a light source that generates near-ultraviolet light.

  The optical shutter 150 selectively emits blue light incident from the backlight 20 and selectively causes the blue light to enter the color conversion substrate 100. By passing through the optical shutter 150, the gradation of the light generated in the backlight 20 is adjusted. As the optical shutter 150, a liquid crystal panel, a liquid crystal panel using an in-cell polarizing plate, a device using MEMS, or the like can be used. When a liquid crystal panel or MEMS is used as the optical shutter 150, it is desirable that the backlight 20 has high directivity. As an alternative to the optical shutter 150 and the backlight 20, it is also conceivable to use an organic EL panel.

  The color conversion substrate 100 includes a phosphor layer 3 and a transparent substrate 4. The phosphor layer 3 includes a main surface 1 and a main surface 2. The transparent substrate 4 is disposed on the main surface 1 of the phosphor layer 3. Incident light in a predetermined frequency region is incident on the main surface 2 of the phosphor layer 3 from the backlight 20, and light is emitted from the main surface 1 of the phosphor layer 3. The main surface 2 is an incident surface on which light enters the phosphor layer 3, and the main surface 1 is an exit surface from which light is emitted from the phosphor layer 3.

  The phosphor layer 3 includes a phosphor such as an organic phosphor, an inorganic phosphor, or a nanophosphor. The phosphor absorbs light incident through the optical shutter 150 and emits fluorescence of each color isotropically. The phosphor layer 3 is formed by arranging and molding a mixture of a phosphor and a binder resin. The phosphor is arranged so that light incident on the phosphor layer 3 from the optical shutter 150 is irradiated to the phosphor. The type of phosphor to be used is preferably selected in consideration of the concentration of the phosphor added, the thickness of the phosphor layer 3 to be formed, the absorption rate, and the like.

  The phosphor layer 3 includes at least a green phosphor that absorbs incident light incident on the phosphor layer 3 and emits green light. The phosphor layer 3 may include phosphors of other colors. The phosphor layer 3 may include a scattering material together with the phosphor or instead of the phosphor.

  As the transparent substrate 4, for example, a glass substrate, a transparent film, or a transparent resin can be employed. The transparent substrate 4 is disposed on the phosphor layer 3 and has an emission surface 9 on the side opposite to the side facing the phosphor layer 3. Light extracted from the display device 200 to the outside is emitted from the emission surface 9.

  In the display device 200, it is also possible to provide a color filter layer on the exit surface 9 side with respect to the phosphor layer 3 as means for improving the color characteristics of the image. The display device 200 can be applied as an image display device that displays an image from the exit surface 9 or an illumination device that emits illumination light of an arbitrary hue from the exit surface 9.

  In the present embodiment, the wavelength region of blue light emitted from the backlight 20 is not less than 390 nm and not more than 510 nm. The wavelength when the emission intensity of blue light is maximum is about 450 nm. The phosphor layer 3 includes a green phosphor that absorbs blue light and emits green fluorescence when blue light is incident thereon. The green phosphor emits green light isotropically. The wavelength region of green light emitted from the green phosphor is not less than 460 nm and not more than 580 nm. The wavelength when the emission intensity of green light is maximum is 520 nm. The phosphor layer 3 may include phosphors of other colors.

  The phosphor layer 3 needs to transmit light having a wavelength emitted by the phosphor. This is because the fluorescence is not emitted from the main surface 1 side, which is the emission surface of the fluorescence, to the outside of the phosphor layer 3 if it does not pass through. Therefore, the phosphor layer 3 containing the green phosphor transmits a certain amount of light with respect to light having a wavelength of 520 nm and the vicinity thereof where the emission intensity of green light is maximum, for example, light in a wavelength region of 500 nm to 560 nm. Need to have a rate. The higher the transmittance, the greater the amount of energy of light emitted from the main surface 1 side to the outside of the phosphor layer 3, which is desirable for use in a fluorescence excitation display.

  On the other hand, the blue light generated in the backlight 20 should ideally have a spectrum in which a peak exists in a delta function in the blue wavelength region. However, it is difficult to realize such a backlight 20, and the actual backlight 20 has an intensity in a wavelength region other than the target wavelength. Since the wavelengths of blue light and green light are close, the blue light emitted from the backlight 20 has a weak intensity in the wavelength region of green light (for example, a wavelength region of 500 nm or more). When the blue light in the wavelength region of green light reaches the phosphor layer 3, it passes through the phosphor layer 3, and is emitted from the main surface 1 to the outside of the phosphor layer 3 as so-called exit light.

  Although it is desirable that the phosphor contained in the phosphor layer 3 absorbs all the blue light of the backlight 20, it is actually difficult to produce such a phosphor material. In particular, since the green light emitted from the green phosphor has a wavelength close to that of the blue light of the backlight 20, the influence of the blue light transmitted through the phosphor layer 3 containing the green phosphor and emitted to the outside as emitted light is large. Become.

  The amount of fluorescence energy emitted by the phosphor is lower than the amount of excitation light energy absorbed by the phosphor. For this reason, the ratio of the missing light in the total energy of the light emitted from the phosphor increases depending on the light distribution characteristics of the backlight 20 so as to affect the display quality of the display device 200. For example, when the backlight 20 has high directivity, that is, when the light intensity in the front direction of the backlight 20 is extremely large compared to the light intensity in the oblique direction, if the light exits from the phosphor layer 3, As for the incident light, the luminance in the front direction is much larger than that in the oblique direction due to the combination of the fluorescence and the exit light.

  As described above, when the backlight 20 having the luminance change due to the polar angle is used, the luminance of the display device 200 may change depending on the viewing angle. Such a luminance change is more likely to occur as the directivity of the backlight 20 is higher, and it is desirable to use the backlight 20 having a higher directivity in the fluorescence excitation display. Therefore, it is necessary to remove this lost light.

  Therefore, the display device 200 according to the present embodiment includes a filter 30 disposed between the backlight 20 and the phosphor layer 3. The filter 30 is disposed on the light source side with respect to the phosphor layer 3. Light generated by the backlight 20 passes through the filter 30 and enters the phosphor layer 3. The filter 30 suppresses passage of light in a part of the wavelength range among the light generated in the backlight 20. The filter 30 transmits light having a wavelength that maximizes the emission intensity of blue light emitted from the backlight 20, and suppresses transmission of light having a wavelength that maximizes the emission intensity of green light emitted by the phosphor. The filter 30 is a wavelength selective cut filter that suppresses transmission of light having a wavelength of at least 500 nm to 560 nm and transmits light having a wavelength of 430 nm to 470 nm.

  Of the blue light generated in the backlight 20, blue light in the main wavelength region passes through the filter 30. The filter 30 is disposed between the backlight 20 and the phosphor layer 3 containing the green phosphor. Unnecessary blue light that passes through the phosphor layer 3 and becomes exiting light is cut by the filter 30. The Incorporating a filter 30 that cuts light in a wavelength range of at least 500 nm to 560 nm and transmits light in a wavelength range of 430 nm to 470 nm closer to the backlight 20 than the color conversion substrate 100 greatly impairs light utilization efficiency. It is possible to remove light leakage without any problem. As a result, it is possible to realize the display device 200 that does not change in luminance depending on the viewing angle.

  Hereinafter, details of the characteristics of the filter 30 will be described. FIG. 2 is a cross-sectional view showing an outline of the emitted light from the phosphor layer 3. In FIG. 2, part of the blue light generated in the backlight 20 excites the phosphor in the phosphor layer 3, and as a result, fluorescence is emitted, and part of the blue light passes through the phosphor layer 3 as light. A state of transmission is schematically illustrated.

  As shown in FIG. 2, the blue light L1 generated by the backlight 20 passes through the filter 30 and enters the phosphor layer 3 as the blue light L4. In the phosphor layer 3, the phosphor absorbs part of the blue light L4 and emits fluorescence.

  The fluorescence is emitted isotropically as shown by the green lights F1 to F5. The green light F1 travels toward the main surface 1 in the thickness direction of the phosphor layer 3 and exits from the phosphor layer 3 along the normal direction of the planar main surface 1. The green lights F <b> 2 and F <b> 3 travel to the main surface 1 side along the oblique direction with respect to the normal direction of the main surface 1 and are emitted from the phosphor layer 3. The green lights F4 and F5 travel to the main surface 2 side.

  Of the blue light L4, light that has not been used as excitation light for exciting the phosphor is emitted from the phosphor layer 3 as exit light, as is the blue light L7. The blue light L7 travels in the same direction as the green light F1, that is, along the normal direction of the main surface 1, and is emitted from the phosphor layer 3.

  Here, the polar angle θ and the azimuth angle φ are defined as follows. FIG. 3 is a schematic diagram showing an outline of the polar angle θ and the azimuth angle φ. In the present specification, the polar angle θ refers to an angle with respect to the planar exit surface 9 of the display device 200 and refers to an angle formed with respect to the normal line of the exit surface 9. As shown in FIG. 3, when assuming a normal to the emission surface 9 from one point on a straight line extending on the emission surface 9, the polar angle θ formed by the straight line extending in one direction with respect to the normal is 90 °. The polar angle θ formed by the straight line extending in the other direction opposite to the one direction is −90 °.

  Further, in this specification, the azimuth angle φ refers to a declination angle with respect to one direction of a straight line extending on the emission surface 9. That is, as shown in FIG. 3, when assuming a normal to the exit surface 9 from one point on the straight line extending on the exit surface 9, the azimuth angle on one side of the straight line with respect to the intersection of the normal and the straight line is It is 0 ° (or 360 °), and the azimuth angle on the other side of the straight line is 180 °.

  Returning to FIG. 2, a part of the blue light L2 generated in the backlight 20 is incident on the phosphor layer 3 as the blue light L5 through the filter 30 and the green light F2 travels in the traveling direction. The light travels along the same direction as the blue light L8, and is emitted from the phosphor layer 3 as exiting light like the blue light L8. Green light F2 and blue light F8 indicate the fluorescence emitted from the phosphor and the exit light transmitted through the phosphor layer 3 at the same polar angle θ.

  A part of the blue light L3 generated in the backlight 20 passes through the filter 30 and enters the phosphor layer 3 as the blue light L6, along the same direction as the green light F3 travels. Then, the light is emitted from the phosphor layer 3 as exit light like the blue light L9. Green light F3 and blue light F9 indicate the fluorescence emitted from the phosphor and the light passing through the phosphor layer 3 at the same polar angle θ.

For a specific wavelength, the luminous intensity of green light emitted from the phosphor at the polar angle θ is defined as a luminous intensity spectrum P _θ . For the same wavelength, at the polar angle θ, the luminous intensity of the blue light generated by the backlight 20 and transmitted through the phosphor layer 3 is i _θ · T _F · T _ph . Here, _iθ is a luminous spectrum of blue light generated in the backlight 20 at a polar angle θ for a specific wavelength, and _TF is a transmittance spectrum of the filter 30 for a specific wavelength. , T _ph is the transmittance spectrum of the phosphor layer 3 for a specific wavelength. That is, for a specific wavelength, at the polar angle θ, the luminous intensity of the light emitted from the phosphor layer 3 is P _θ + (i _θ · T _F · T _ph ), that is, the luminous intensity of fluorescence and the luminous intensity of missing light Is the sum of

The sum of {P _θ + (i _θ · T _F · T _ph )} integrated over all wavelengths is the luminous intensity l _θ of the emitted light from the phosphor layer 3 at the polar angle θ. In other words, the luminous intensity l _theta of the light emitted from the phosphor layer 3 at a polar angle theta is expressed by the following equation (1).
_{(1) l θ = ∫ {} P θ + (i θ · T F · T ph)} dλ
That is, the luminous intensity lθ _{represents the} luminous intensity of the light that is emitted from the phosphor layer 3 in the polar angle θ direction and that is the sum of the fluorescence of all wavelengths and the light of all wavelengths.

FIG. 4 is a diagram illustrating the relationship between the polar angle θ and the luminous intensity when the luminance is uniform regardless of the viewing angle of the display device 200. The horizontal axis in FIG. 4 indicates the polar angle. In the direction directly in front of the emission surface 9 of the display device 200, the polar angle θ is 0 °. The vertical axis in FIG. 4 indicates the luminous intensity, that is, the size of the light beam emitted from the display device 200 in the polar angle θ direction. The luminous intensity of the emitted light from the display device 200 in the direction where the polar angle θ is 0 ° is defined as l ₀ . The luminous intensity ₁₀ is the luminous intensity obtained by integrating the sum of the luminous intensity of fluorescence and the luminous intensity of light at all polarities at a polar angle of 0 °.

FIG. 4 shows the luminous intensity of the emitted light from the point when the position of the origin in FIG. 4 is considered as a certain point on the emission surface 9 of the display device 200. If the luminance of the display device 200 is truly uniform regardless of the observation angle, the relationship between the polar angle and the luminous intensity follows the equation f (θ) = l ₀ · cos θ shown in FIG. In the present embodiment, if the light emitted from the display device 200 via the emission surface 9 is within a certain range with respect to f (θ) shown in FIG. 4, the display device 200 has a uniform luminance regardless of the observation angle. Evaluate that there is. That is, in the display device 200 that can be evaluated as having uniform brightness regardless of the observation angle, the polar angle distribution of the luminous intensity of the emitted light from the phosphor layer 3 is in a certain range.

More specifically, when the polar angle θ and the luminous intensity l _θ of the emitted light from the phosphor layer 3 at the polar angle θ are in the range of −85 ° ≦ θ ≦ 85 °, the following relational expression (2) is satisfied. Evaluate whether to meet.
(2) 0.90 · A · cos θ ≦ l _θ ≦ 1.10 · A · cos θ
Wherein A is any real number in the 1.11 times the range of 0.91 or more times the intensity l ₀ of the light emitted from the phosphor layer 3 at a polar angle 0 °, the luminous intensity in the polar angle 0 ° ranges that will fit in ± 10% with respect to l _0. When the display device 200 satisfies this relational expression, the display device 200 is realized in which the change in luminance is sufficiently small regardless of the angle at which the display device 200 is viewed, and the luminance is uniform at all viewing angles. Can be evaluated. This conditional expression clarifies conditions for achieving uniform luminance of the display device 200.

  FIG. 5 is a graph showing the luminous intensity polar angle distribution of the emitted light from the phosphor layer 3. In FIG. 5, the horizontal axis indicates the polar angle, and the vertical axis indicates the relative luminous intensity. A curve drawn with a solid line in FIG. 5 is an actual measurement value of the luminous intensity distribution of the emitted light from the phosphor layer 3. In addition, regarding the outgoing light from the phosphor layer 3, the range outside the polar angle ± 70% cannot be measured due to the measurement limit, so in FIG. 5, the outgoing light in the polar angle range of −70 ° to 70 ° is used. The light intensity distribution is shown.

For example, it is assumed that the light emitted from the phosphor layer 3 shows an actually measured value of the luminous intensity distribution as shown in FIG. In this case, the real A and 0.96 times the intensity l ₀ of the light emitted from the phosphor layer 3 at a polar angle 0 °. In other words, the A = 0.96 · _{l 0} in the conditional expression. A curve drawn by a dotted line in FIG. 5 indicates a function f (θ) = A · cos θ = 0.96 · l ₀ · cos θ of the polar angle θ. Two curves drawn with a chain line in FIG. 5 indicate 0.90 times and 1.10 times of the function f (θ).

Thus, by appropriately selecting the real A in 1.11 times or less in the range 0.91 times the intensity l ₀ of the polar angle 0 °, the luminous intensity l of the emitted light indicated by the solid line in FIG. 5 _θ is in the range of 0.90 times or more and 1.10 times or less of A · cos θ in the range where the polar angle θ is −85 ° or more and 85 ° or less. Therefore, since the polar angle luminous intensity of the light emitted from the phosphor layer 3 in the theta l _theta is to satisfy the condition described above, the display device 200 can be evaluated to be uniform luminance regardless of the viewing angle.

  The characteristics of the filter 30 greatly depend on the orientation characteristics of the backlight 20 and the transmittance of the phosphor layer 3. The filter 30 only needs to have a transmittance that transmits blue light. It is desirable that the transmittance of blue light is as high as possible. By providing the filter 30, the luminous intensity of light passing through the phosphor layer 3 can be reduced. In addition, by determining the characteristics of the filter 30 so as to satisfy the above formulas (1) and (2) without depending on the azimuth angle φ, the entire viewing angle can be obtained regardless of the observation angle even if light leakage occurs. The display device 200 with uniform luminance can be realized, and the display device 200 with uniform luminance can be intentionally manufactured. Therefore, it is possible to prevent display quality from being deteriorated due to light passing through the phosphor layer 3.

(Embodiment 2)
The display device 200 according to the second embodiment includes the phosphor layer 3 including a plurality of pixels that can emit red light, green light, and blue light, respectively, and the display device 200 is white light by superimposing these colors. Can be displayed. When the display device 200 displays white light, the error of the chromaticity xy needs to be within ± 0.02 in order to suppress the color change depending on the observation angle to such an extent that it cannot be felt by human eyes. In the second embodiment, a condition for evaluating that the change in chromaticity of the display device 200 is within ± 0.02 and that the display device 200 has uniform chromaticity regardless of the observation angle will be described.

  FIG. 6 shows that in the display device 200 configured by RGB pixels, when the output light from the B pixel has an error of 0% from the conditional expression, the white display chromaticity is ± 0 when the RG deviates from the conditional expression It is a graph which shows whether it changes more than 0.02. The G coefficient on the horizontal axis of the graph of FIG. 6 indicates an error from the conditional expression of the luminous intensity of light emitted from the G pixel. The R coefficient on the vertical axis indicates an error from the conditional expression of the luminous intensity of light emitted from the R pixel. For example, the G coefficient of 1.05 means that the error from the conditional expression of the luminous intensity of light emitted from the G pixel is + 5%.

  The chromaticity change is ± 0.02 on the line plotted in the graph shown in FIG. In the graph of FIG. 6, if it is within the area surrounded by the plot line, the chromaticity change is within ± 0.02 from the state in accordance with the conditional expression for all RGB. When a similar graph is created by varying the error from the conditional expression of the B pixel, if the luminance of all RGB is within ± 7% of the conditional expression, the chromaticity change of the display device 200 is 0.02. Fits within. Therefore, if the measured value of the luminous intensity distribution falls within a range of ± 7% with respect to the conditional expression, a display device in which the chromaticity is within ± 0.02 and the chromaticity is uniform regardless of the observation angle is realized. Can be evaluated.

In other words, the polar angle luminous intensity of the light emitted from the phosphor layer 3 in the theta l _theta is in the range of -85 ° ≦ θ ≦ 85 °, to assess whether it satisfies the relational expression (3).
(3) 0.93 · B · cos θ ≦ l _θ ≦ 1.07 · B · cos θ
Wherein B is any real number in the 1.076 times the range 0.93 times the intensity l ₀ of the light emitted from the phosphor layer 3 at a polar angle 0 °, the luminous intensity in the polar angle 0 ° ranges that fall ± 7% with respect to l _0. When the display device 200 satisfies this relational expression, the chromaticity xy falls within an error of ± 0.02, and if the chromaticity xy is within ± 0.02, it is unlikely that a human will feel a color change. Therefore, it can be evaluated that the display device 200 having uniform brightness and chromaticity at all viewing angles has been realized. This conditional expression clarifies the conditions for achieving chromaticity uniformity of the display device 200, and it can be evaluated that a display apparatus that satisfies the conditional expression has a characteristic that the chromaticity does not change depending on the observation angle.

  FIG. 7 is a graph showing the luminous intensity polar angle distribution of the light emitted from the R phosphor. FIG. 8 is a graph showing the luminous intensity polar angle distribution of the emitted light from the G phosphor. FIG. 9 is a graph showing the luminous intensity polar angle distribution of the emitted light from the scattering material in the B pixel. 7, 8, and 9, the horizontal axis indicates the polar angle, and the vertical axis indicates the relative luminous intensity.

If light emitted from the R phosphor is luminous intensity distribution as shown in solid line in FIG. 7, the real B 1.06 times the intensity l ₀ of the light emitted from the R phosphor in the polar angle 0 °. That is, the B = 1.06 · _{l 0} in conditional expressions. A curve drawn with a dotted line in FIG. 7 represents a function f (θ) = B · cos θ = 1.06 · l ₀ · cos θ of the polar angle θ. Two curves drawn with a chain line in FIG. 7 indicate 0.93 times and 1.07 times the above function f (θ).

If light emitted from the G phosphor is a luminous intensity distribution as shown in solid line in FIG. 8, the real B and 1.006 times the intensity l ₀ of the light emitted from the G phosphor in the polar angle 0 °. That is, B in the conditional expression is set to 1.006 · ₁₀ . A curve drawn by a dotted line in FIG. 8 indicates a function f (θ) = B · cos θ = 1.006 · l ₀ · cos θ of the polar angle θ. Two curves drawn with a chain line in FIG. 8 indicate 0.93 times and 1.07 times the above function f (θ).

When the light emitted from the scattering material in the B pixel is light intensity distribution as shown by the solid line in FIG. 9, the real B 0.93 times the intensity l ₀ of the light emitted from the scattering material at a polar angle 0 ° . That is, the B = 0.93 · _{l 0} in conditional expressions. A curve drawn by a dotted line in FIG. 9 indicates a function f (θ) = B · cos θ = 0.93 · l ₀ · cos θ of the polar angle θ. Two curves drawn with a chain line in FIG. 9 indicate 0.93 times and 1.07 times the above function f (θ).

Thus, by appropriately selecting the real B in 1.076 times the range 0.93 times the intensity l ₀ of the polar angle 0 °, the light emitted from each phosphor of RGB luminous intensity l _theta Is in the range of 0.93 to 1.07 times B · cos θ in the range of polar angle θ of −85 ° to 85 °. Therefore, since the polar angle theta intensity l _theta of the light emitted from the phosphor layer 3 in is to satisfy the condition described above, the display device 200 can be evaluated to be uniform chromaticity irrespective of the viewing angle.

  The filter 30 only needs to have a transmittance that transmits blue light. It is desirable that the transmittance of blue light is as high as possible. By providing the filter 30, the luminous intensity of light passing through the phosphor layer 3 can be reduced. Further, by determining the characteristics of the filter 30 so as to satisfy the above formulas (1) and (3) without depending on the azimuth angle φ, the chromaticity is uniform regardless of the observation angle even if light leakage occurs. Display device 200 can be realized, and display device 200 whose luminance and chromaticity do not change depending on the observation angle can be intentionally manufactured. Therefore, it is possible to prevent display quality from being deteriorated due to light passing through the phosphor layer 3.

(Embodiment 3)
FIG. 10 is a cross-sectional view showing the display device 200 according to the third embodiment. In the display device 200 according to the third embodiment, the backlight 20 emits light having a blue wavelength. As shown in FIG. 10, the phosphor layer 3 includes a red phosphor layer 5r and a green phosphor layer 5g. The phosphor layer 3 also includes a diffusion layer 6. The red phosphor layer 5r, the green phosphor layer 5g, and the diffusion layer 6 are partitioned by the partition wall 7, and are arranged in an array with a space therebetween. The phosphor layer 3 is coated with phosphor and scattering material for each pixel.

  The red phosphor layer 5r includes a red phosphor that absorbs incident light incident on the red phosphor layer 5r and emits red light. The green phosphor layer 5g includes a green phosphor that absorbs incident light incident on the green phosphor layer 5g and emits green light. The diffusion layer 6 diffuses the incident light incident on the diffusion layer 6 and emits it to the outside. The diffusion layer 6 includes a transparent resin as a binder and a plurality of scattering particles as fillers scattered in the resin. The filler may be any material that reflects and scatters light supplied to the phosphor layer 3 via the optical shutter 150.

  The phosphor layer 3 includes a red phosphor layer 5r that absorbs blue light and excites red light, a green phosphor layer 5g that absorbs blue light and excites green light, and a diffusion layer that completely scatters blue light. 6 are included. Blue light from the backlight 20 is incident on the red phosphor layer 5r, the green phosphor layer 5g, and the diffusion layer 6 to cause red and green light fluorescence and blue light scattering. The light exits from the exit surface 9. Accordingly, the display device 200 is provided as a video display device capable of displaying a full color video.

  As the optical shutter 150, a liquid crystal display panel is used. In this case, as shown in FIG. 10, the optical shutter 150 is a glass substrate 22 which is a TFT (Thin Film Transistor) substrate disposed on the backlight 20 side, and a counter substrate disposed on the color conversion substrate 100 side. The glass substrate 24 and the liquid crystal layer 23 enclosed between the glass substrate 22 and the glass substrate 24 are included. An annular seal member (not shown) for sealing the liquid crystal layer 23 is provided between the glass substrates 22 and 24 along the outer peripheral edge portions of the glass substrates 22 and 24. A polarizing plate 21 is attached to the outer surface of the glass substrate 22, and a polarizing plate 25 is attached to the outer surface of the glass substrate 24.

  A source wiring is formed on the surface of the glass substrate 22 on the liquid crystal layer 23 side, and an insulating layer is formed so as to cover the source wiring. Further, pixel electrodes are arranged on the surface of the insulating layer so as to correspond to the respective pixels. The pixel electrode is formed of a transparent conductive film such as an ITO (indium tin oxide) film. A counter electrode is formed on the surface of the glass substrate 24 on the liquid crystal layer 23 side. The counter electrode is formed of a transparent conductive film such as an ITO film, for example.

  When a voltage is applied between the pixel electrode on the glass substrate 22 side and the counter electrode on the glass substrate 24 side, the molecular orientation of the liquid crystal layer 23 in the pixel changes. The optical shutter 150 controls the light transmittance in the pixel by a combination of the change in the polarization state by the liquid crystal layer 23 and the polarizing plates 21 and 25.

  In the third embodiment, in the display device 200 having the above-described configuration, the filter 30 satisfies the above expressions (1) and (2) without depending on the azimuth angle φ, or the above expressions (1) and (3). ) And possesses a transmittance that transmits blue light. By determining the characteristics of the filter 30 in this manner, the display device 200 with uniform brightness regardless of the observation angle or the display device 200 without further chromaticity change can be realized, and the display device 200 with uniform brightness is intentionally manufactured. can do. Therefore, it is possible to prevent display quality from being deteriorated due to light passing through the phosphor layer 3.

  Note that the filter 30 is not limited to the arrangement shown in FIG. 10, and for example, a filter may be installed between the optical shutter 150 and the phosphor layer 3.

(Embodiment 4)
FIG. 11 is a cross-sectional view showing a display device 200 according to the fourth embodiment. The display device 200 according to the fourth embodiment has basically the same configuration as that of the display device according to the third embodiment shown in FIG. 10, and the emission surface 9 side opposite to the backlight 20 with respect to the phosphor layer 3. 1 in that a color filter 8 is provided. The color filter 8 includes a color filter 8r disposed between the red phosphor layer 5r and the transparent substrate 4, a color filter 8g disposed between the green phosphor layer 5g and the transparent substrate 4, and a diffusion layer 6. And a color filter 8 b disposed between the transparent substrate 4 and the transparent substrate 4.

  By installing the color filter 8, the emitted light from the phosphor layer 3 is selectively transmitted, so that the color characteristics of the image can be improved. In FIG. 11, the color filter 8 is installed between all the color pixels and the transparent substrate 4, but the configuration is not limited thereto. For example, the color filter 8b on the diffusion layer 6 may be omitted, and the color filter 8 may be formed only on the red phosphor layer 5r and the green phosphor layer 5g.

In the fourth embodiment, the light emitted from the phosphor layer 3 is further emitted from the emission surface 9 to the outside of the display device 200 via the color filter 8. In this case, assuming that the transmittance spectrum T _CF of the color filter, the luminous intensity of light emitted from the phosphor layer 3 at a polar angle θ is P _θ · T _CF + (i _θ · T _F * _Tph * _TCF ). Therefore, the light intensity L _{θ of} the light transmitted through the color filter 8 at the polar angle θ is expressed by the following relational expression (4).
(4) _Lθ = ∫ { _Pθ · T _CF + (i _θ · T _F · T _ph · T _CF )} dλ
The luminosity L _theta i.e., emitted through the color filter 8 in the polar angle theta direction indicates the intensity of leakage light and the light obtained by summing the fluorescence and all wavelengths of all wavelengths.

If the polar angle θ and the luminous intensity L _{θ of} the light transmitted through the color filter 8 at the polar angle θ satisfy the following relational expression (5) in the range of −85 ° ≦ θ ≦ 85 °, the display device: It can be evaluated that the display device 200 in which the change in luminance is sufficiently small regardless of the angle at which 200 is viewed and the luminance is uniform at all viewing angles has been realized.
(5) 0.90 · C · cos θ ≦ L _θ ≦ 1.10 · C · cos θ
Here, C is an arbitrary real number in the range of 0.91 to 1.11 times the light intensity L ₀ of the light transmitted through the color filter 8 at the polar angle 0 °, and the light intensity L at the polar angle 0 °. _The range is within ± 10% of ₀ .

  In the display device 200 having the above-described configuration, the filter 30 satisfies the above expressions (4) and (5) without depending on the azimuth angle φ and has a transmittance that transmits blue light. Good. By determining the characteristics of the filter 30 in this manner, the display device 200 with uniform brightness regardless of the observation angle can be realized, and the display device 200 with uniform brightness can be intentionally manufactured. Therefore, it is possible to prevent display quality from being deteriorated due to light passing through the phosphor layer 3.

If the polar angle θ and the luminous intensity L _{θ of} the light transmitted through the color filter 8 at the polar angle θ satisfy the following relational expression (6) in the range of −85 ° ≦ θ ≦ 85 °: Even if the display device 200 is viewed from any angle, the change in chromaticity is within 0.02, and it can be evaluated that the display device 200 having uniform chromaticity at any viewing angle has been realized.
(6) 0.93 · D · cos θ ≦ L _θ ≦ 1.07 · D · cos θ
Here, D is an arbitrary real number in the range of 0.93 times or more and 1.076 times or less of the light intensity L ₀ of the light transmitted through the color filter 8 at the polar angle 0 °, and the light intensity L at the polar angle 0 °. _The range is within ± 7% with respect to ₀ .

  When the display device 200 satisfies the relational expression (6), the chromaticity xy falls within an error of ± 0.02, and when the chromaticity xy is within ± 0.02, the color change is perceived by human eyes. Therefore, it can be evaluated that the display device 200 having uniform brightness and chromaticity at all viewing angles has been realized. Conditional expression (6) clarifies the conditions for achieving uniform chromaticity of the display device 200, and it can be evaluated that a display device that satisfies the conditional expression has a characteristic that the chromaticity does not change depending on the observation angle. it can.

(Embodiment 5)
FIG. 12 is a cross-sectional view showing display device 200 according to the fifth embodiment. The display device 200 according to the fifth embodiment has basically the same configuration as the display device according to the third embodiment shown in FIG. 10, and the light source side filter is omitted from the red phosphor layer 5r and the diffusion layer 6. However, the difference is that the filter 30 is disposed only between the green phosphor layer 5g and the backlight 20, and the filter is disposed only in the green pixel.

  If there is a filter 30 in the red pixel that is the region of the red phosphor layer 5 r or the blue pixel that is the region of the diffusion layer 6, it is difficult to make the transmittance 100% wavelength selective. Is only reduced, and there is no merit. Therefore, it is desirable to have the filter 30 only in the green pixel. In this case, the efficiency of light can be improved because the efficiency of the red and blue pixels is not impaired by the filter 30.

  The position of the filter 30 is not limited to the example shown in FIG. 12, and may be arranged anywhere as long as it is between the backlight 20 and the green phosphor layer 5g. For example, it is conceivable to form the filter 30 inside a liquid crystal panel that functions as the optical shutter 150.

  In the display device 200 having the above configuration, the filter 30 satisfies the above formulas (1) and (2) without depending on the azimuth angle φ, or satisfies the above formulas (1) and (3), and emits blue light. As long as it has such a transmittance as to transmit light. By determining the characteristics of the filter 30 in this manner, the display device 200 with uniform brightness regardless of the observation angle or the display device 200 without further chromaticity change can be realized, and the display device 200 with uniform brightness is intentionally manufactured. can do. Therefore, it is possible to prevent display quality from being deteriorated due to light passing through the phosphor layer 3.

  Although the embodiments of the present invention have been described above, the configurations of the embodiments may be appropriately combined. In addition, it should be considered that the embodiment disclosed this time is illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1, 2 main surface, 3 phosphor layer, 4 transparent substrate, 5 g green phosphor layer, 5r red phosphor layer, 6 diffusion layer, 7 partition wall, 8, 8b, 8 g, 8r color filter, 9 exit surface, 20 Backlight, 21, 25 polarizing plate, 22, 24 glass substrate, 23 liquid crystal layer, 30 filter, 100 color conversion substrate, 150 optical shutter, 200 display device.

Claims (7)

A light source unit that emits first light;
An optical shutter that selectively emits light incident from the light source unit;
A phosphor layer that is arranged so that light from the optical shutter is incident thereon, and includes a phosphor that absorbs light incident from the optical shutter and emits fluorescent light of the second light;
It is disposed between the light source unit and the phosphor layer, transmits light having a wavelength that maximizes the emission intensity of the first light, and transmits light having a wavelength that maximizes the emission intensity of the second light. A display device comprising a filter. Polarity angle θ, luminous intensity spectrum P _θ of the second light emitted from the phosphor layer at polar angle θ, luminous intensity spectrum i _θ of the first light at polar angle θ, transmittance spectrum T _{F of} the filter, phosphor When the transmittance spectrum T _ph of the layer is used, the luminous intensity l _θ of the emitted light from the phosphor layer at the polar angle _θ is
_{l θ = ∫ {P θ +} (i θ · T F · T ph)} dλ
Represented by
When the polar angle θ and the luminous intensity l _θ of the light emitted from the phosphor layer at the polar angle θ are in the range of −85 ° ≦ θ ≦ 85 °, the light emitted from the phosphor layer at the polar angle 0 ° For any real number A in the range of 0.91 to 1.11 times the luminous intensity,
0.90 · A · cos θ ≤ l _θ ≤ 1.10 · A · cos θ
The display device according to claim 1, wherein: When the polar angle θ and the luminous intensity l _θ of the light emitted from the phosphor layer at the polar angle θ are in the range of −85 ° ≦ θ ≦ 85 °, the light emitted from the phosphor layer at the polar angle 0 ° For any real number B in the range of 0.93 times to 1.076 times the luminous intensity,
0.93 ・ B ・_cosθ ≦ l _θ ≦ 1.07 ・ B ・_cosθ
The display device according to claim 2, wherein: The first light is blue light;
The phosphor layer includes a green phosphor that emits green light.
The display device according to claim 1, wherein the filter is disposed between the light source unit and the green phosphor.   5. The display device according to claim 1, further comprising a color filter that is disposed on the opposite side of the light source unit with respect to the phosphor layer and selectively transmits light emitted from the phosphor layer. . Polarity angle θ, luminous intensity spectrum P _θ of the second light emitted from the phosphor layer at polar angle θ, luminous intensity spectrum i _θ of the first light at polar angle θ, transmittance spectrum T _{F of} the filter, phosphor When the transmittance spectrum T _{ph of} the layer and the transmittance spectrum T _CF of the color filter are used, the light intensity L _θ of the light transmitted through the color filter at the polar angle _θ is
L _θ = ∫ {P _θ · T _CF + (i _θ · T _F · T _ph · T _CF )} dλ
Represented by
The polar angle θ and the light intensity L _{θ of} the light transmitted through the color filter at the polar angle θ are the light intensity of the light transmitted through the color filter at a polar angle of 0 ° in the range of −85 ° ≦ θ ≦ 85 °. For any real number C in the range of 0.91 times or more and 1.11 times or less,
0.90 · C · cos θ ≤ L _θ ≤ 1.10 · C · cos θ
The display device according to claim 5, wherein: The polar angle θ and the light intensity L _{θ of} the light transmitted through the color filter at the polar angle θ are the light intensity of the light transmitted through the color filter at a polar angle of 0 ° in the range of −85 ° ≦ θ ≦ 85 °. For any real number D in the range of 0.93 times or more and 1.076 times or less,
0.93 · D · cos θ ≤ L _θ ≤ 1.07 · D · cos θ
The display device according to claim 6, wherein:

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