Display device using ambient light a lighting panel
First Claim
1. A display device comprising:
- a non light-emitting type display element for controlling the transmission of incident light to display an image, a light radiating unit arranged at the back of the display element for emitting illuminating light toward the display element and reflecting ambient light incident from the front of the display element at a given reflectivity toward the display element, the light radiating unit comprising a light source, a light guide, and at least one reflective film provided on the light guide for reflecting the ambient incident light into the light guide toward the display element, the light guide comprising an incident end face, at at least one end face, for taking in illuminating light from the light source, and a front face made up to a stepwise face, the stepwise face including step faces which become lower stepwise from the side of the incident end face to the other side and step-level-difference faces each of which connects the step faces which are adjacent, each of the step-level-difference faces including an emitting face for emitting the illuminating light projected from the incident end face, and an illumination brightness controller for controlling the intensity of the illuminating light so that the screen brightness of the display element comprising the total of reflected light of the ambient light reflected on the light radiating unit and transmitted light of the illuminating light is set up into a predetermined range according to the reflectivity of the light radiating unit and the environmental illumination of the ambient light radiated from the front of the display element.
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Accused Products
Abstract
A display device includes a non light-emitting type display element for controlling the transmission of incident light to display an image, a light radiating unit having a light source and a photoconductor, and arranged at the back of the display element for emitting illuminating light toward the display element and reflecting ambient light incident from the front of the display element at a given reflectivity toward the display element. An illumination brightness controller is provided for controlling the intensity of the illuminating light so that the screen brightness of the display element comprising the total of reflected light of the ambient light reflected on the photoconductor and transmitted light of the illuminating light is set up into a predetermined range according to the reflectivity of the photoconductor and the environmental illumination of the ambient light radiated from the front of the display element.
126 Citations
24 Claims
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1. A display device comprising:
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a non light-emitting type display element for controlling the transmission of incident light to display an image, a light radiating unit arranged at the back of the display element for emitting illuminating light toward the display element and reflecting ambient light incident from the front of the display element at a given reflectivity toward the display element, the light radiating unit comprising a light source, a light guide, and at least one reflective film provided on the light guide for reflecting the ambient incident light into the light guide toward the display element, the light guide comprising an incident end face, at at least one end face, for taking in illuminating light from the light source, and a front face made up to a stepwise face, the stepwise face including step faces which become lower stepwise from the side of the incident end face to the other side and step-level-difference faces each of which connects the step faces which are adjacent, each of the step-level-difference faces including an emitting face for emitting the illuminating light projected from the incident end face, and an illumination brightness controller for controlling the intensity of the illuminating light so that the screen brightness of the display element comprising the total of reflected light of the ambient light reflected on the light radiating unit and transmitted light of the illuminating light is set up into a predetermined range according to the reflectivity of the light radiating unit and the environmental illumination of the ambient light radiated from the front of the display element. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
a screen brightness of 20-200 nits at an environmental illumination of 50 luxes, a screen brightness of 30-300 nits at an environmental illumination of 1000 luxes, and a screen brightness of 400-4000 nits at an environmental illumination of 30000 luxes.
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3. A display device according to claim 1, wherein the illumination brightness controller controls the screen brightness, according to the environmental illumination, to the brightness corresponding to curves represented by quadratic functions satisfying the following ranges:
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a screen brightness of 20-60 nits at an environmental illumination of 50 luxes, a screen brightness of 60-200 nits at an environmental illumination of 1000 luxes, and a screen brightness of 1000-3000 nits at an environmental illumination of 30000 luxes.
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4. A display device according to claim 1, wherein the illumination brightness controller controls the screen brightness, according to the environmental illumination, to satisfy:
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5. A display device according to claim 1, wherein the illumination brightness controller controls the screen brightness, according to the environmental illumination, to satisfy:
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6. A display device according to claim 1, wherein the illumination brightness controller controls the brightness of the illuminating light from the light radiating unit at an environmental illumination that is, at lowest, higher than the illumination inside a room.
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7. A display device according to claim 6, wherein the illumination brightness controller controls the brightness of the illuminating light from the light radiating unit in the range in which the environmental illumination is from not more than 50 luxes to more than about 30000 luxes.
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8. A display device according to claim 1, wherein the illumination brightness controller controls the brightness of illuminating light from the light radiating unit in a manner that, within the illumination range in which the environmental illumination is lower than indoor illumination, the brightness of the illuminating light is continuously lowered as the environmental illumination becomes low.
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9. A display device according to claim 1, wherein the illumination brightness controller controls the brightness of illuminating light from the light radiating unit in a manner that, within the illumination range in which the environmental illumination is higher than the indoor illumination and is not more than a given illumination, the brightness of the illuminating light is continuously raised as the environmental illumination rises and,
within the range in which the environmental illumination exceeds the given illumination, the brightness of the illuminating light is continuously lowered as the environmental illumination further rises. -
10. A display device according to claim 1, wherein the illumination brightness controller controls the brightness of illuminating light from the light radiating unit in a manner that:
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1) within the illumination range in which the environmental illumination is lower than indoor illumination, the brightness of the illuminating light is lowered as the environmental illumination becomes low;
2) within the illumination range in which the environmental illumination is higher than the indoor illumination and is not more than a given illumination, the brightness of the illuminating light is raised as the environmental illumination rises, 3) within the range in which the environmental illumination exceeds the given illumination, the brightness of the illuminating light is lowered as the environmental illumination further rises.
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11. A display device according to claim 1, wherein the illumination brightness controller has an illumination detector for measuring the environmental illumination, and a brightness adjusting circuit for controlling the brightness of illuminating light emitted from the light radiating unit on the basis of the measured environmental illumination.
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12. A display device according to claim 1, wherein the light guide has a back face opposite to the reflective faces, and the back face is made up to a light diffusing face for averaging the brightness distribution, in the width direction of the light guide, of the illuminating light projected from the incident end face.
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13. A display device according to claim 12, wherein a light diffusing film is disposed between the light radiating unit and the display element.
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14. A display device according to claim 1, which further comprises a reflecting polarizer disposed between the light radiating unit and the display element, the reflecting polarizer having a reflection axis and a transmission axis crossing each other at substantially right angles and a property of reflecting incident light of the polarized component along the reflection axis and transmitting incident light of the polarized component along the transmission axis.
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15. A display device according to claim 14, wherein the display element comprises a liquid crystal display element having on each of its front and back faces a polarizer, and the reflecting polarizer is arranged so that its transmission axis is substantially parallel to the transmission axis of the polarizer at the back side of the liquid crystal display element.
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16. A display device according to claim 1, wherein the display element has a liquid crystal display element wherein among a pair of substrates at the front and back sides oppositely to each other through a liquid crystal layer, one substrate has on its inner face first electrodes, and the other substrate has on its inner face at least one second electrode whose portions opposite to the first electrodes are respectively made up to pixel areas, and a color filter having an area smaller than the area of each of the pixel areas is disposed on either of the substrate, corresponding to each of the pixel areas.
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17. A display device according to claim 16, wherein each of the pixel areas of the liquid crystal display element has a filter-corresponding area covered with a color filter having an area smaller than the pixel area, and a non-filter area arranged around the filter-corresponding area and not covered with the color filter.
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18. A display device comprising:
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a non light-emitting type display element, a transmission display system comprising a light radiating unit, which is arranged at the back of the display element, for emitting illuminating light toward the display element, wherein the light radiating unit comprises a light source, a light guide which comprises an incident end face, at at least one end face, for taking in illuminating light from the light source, a front face made up to a stepwise face comprising step faces which become lower stepwise from the side of the incident end face to the other side and step-level-difference faces each of which connects the step faces which are adjacent, and emitting faces formed in the step-level-difference faces, for emitting the illuminating light projected from the incident end face toward the display element, and at least one reflective film for reflecting the ambient light toward the display element, a reflection display system for reflecting the ambient light projected from the front of the display element on the light radiating unit and emitting the light ahead of the display element, and a screen brightness compensating display system for emitting the illuminating light from the light radiating unit and compensating the screen brightness of the display element based on the reflection display system by the emitted illuminating light, the reflectivity of the ambient light in the reflection display system being about 16% or more when the transmissivity of the display element is controlled to the maximum. - View Dependent Claims (19, 20, 21)
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22. A display device comprising:
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a non light-emitting type display element for controlling the transmission of incident light to display an image, a light radiating unit arranged at the back of the display element for emitting illuminating light toward the display element and reflecting ambient light incident from the front of the display element at a given reflectivity toward the display element, and an illumination brightness controller for controlling the intensity of the illuminating light so that the screen brightness of the display element comprising the total of reflected light of the ambient light reflected on the light radiating unit and transmitted light of the illuminating light is set up into a predetermined range according to the reflectivity of the light radiating unit and the environmental illumination of the ambient light radiated from the front of the display element, wherein the light radiating unit comprises a light guide, a light source arranged at at least one end of the light guide, and an optical member arranged at the front side of the light guide, 1) the light guide comprising an incident end face, at at least one end face, for taking in illuminating light from the light source, a front face made up to a stepwise face comprising step faces which become lower stepwise from the side of the incident end face to the other side and step-level-difference faces each of which connects the step faces which are adjacent, reflective films disposed on the respective step faces of the light guide, for reflecting the ambient light toward the display element, and emitting faces formed in the respective step-level-difference faces, for emitting the illuminating light projected from the incident end face toward the display element, and 2) the optical member comprising an element which is arrange at the front side of the light guide and is for transmitting the ambient light projected from the front of the display element and emitting the reflected light of the ambient light which is reflected on the reflective films on the respective step faces of the light guide and the illuminating light emitted from the respective step-level-difference faces of the light guide toward the display element to convert the advancing direction of the light. - View Dependent Claims (23, 24)
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Specification